Add m-esr52 at 52.6.0

35 files changed, 34355 insertions, 0 deletions

diff --git a/js/src/jit/arm/Architecture-arm.cpp b/js/src/jit/arm/Architecture-arm.cpp
new file mode 100644
index 0000000000..3fcdbb2cc8
--- /dev/null
+++ b/js/src/jit/arm/Architecture-arm.cpp
@@ -0,0 +1,444 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "jit/arm/Architecture-arm.h"
+
+#if !defined(JS_SIMULATOR_ARM) && !defined(__APPLE__)
+#include <elf.h>
+#endif
+
+#include <fcntl.h>
+#include <unistd.h>
+
+#include "jit/arm/Assembler-arm.h"
+#include "jit/RegisterSets.h"
+
+#if !defined(__linux__) || defined(ANDROID) || defined(JS_SIMULATOR_ARM)
+// The Android NDK and B2G do not include the hwcap.h kernel header, and it is not
+// defined when building the simulator, so inline the header defines we need.
+# define HWCAP_VFP        (1 << 6)
+# define HWCAP_NEON       (1 << 12)
+# define HWCAP_VFPv3      (1 << 13)
+# define HWCAP_VFPv3D16   (1 << 14) /* also set for VFPv4-D16 */
+# define HWCAP_VFPv4      (1 << 16)
+# define HWCAP_IDIVA      (1 << 17)
+# define HWCAP_IDIVT      (1 << 18)
+# define HWCAP_VFPD32     (1 << 19) /* set if VFP has 32 regs (not 16) */
+# define AT_HWCAP 16
+#else
+# include <asm/hwcap.h>
+# if !defined(HWCAP_IDIVA)
+#  define HWCAP_IDIVA     (1 << 17)
+# endif
+# if !defined(HWCAP_VFPD32)
+#  define HWCAP_VFPD32    (1 << 19) /* set if VFP has 32 regs (not 16) */
+# endif
+#endif
+
+namespace js {
+namespace jit {
+
+// Parse the Linux kernel cpuinfo features. This is also used to parse the
+// override features which has some extensions: 'armv7', 'align' and 'hardfp'.
+static uint32_t
+ParseARMCpuFeatures(const char* features, bool override = false)
+{
+    uint32_t flags = 0;
+
+    // For ease of running tests we want it to be the default to fixup faults.
+    bool fixupAlignmentFault = true;
+
+    for (;;) {
+        char ch = *features;
+        if (!ch) {
+            // End of string.
+            break;
+        }
+        if (ch == ' ' || ch == ',') {
+            // Skip separator characters.
+            features++;
+            continue;
+        }
+        // Find the end of the token.
+        const char* end = features + 1;
+        for (; ; end++) {
+            ch = *end;
+            if (!ch || ch == ' ' || ch == ',')
+                break;
+        }
+        size_t count = end - features;
+        if (count == 3 && strncmp(features, "vfp", 3) == 0)
+            flags |= HWCAP_VFP;
+        else if (count == 4 && strncmp(features, "neon", 4) == 0)
+            flags |= HWCAP_NEON;
+        else if (count == 5 && strncmp(features, "vfpv3", 5) == 0)
+            flags |= HWCAP_VFPv3;
+        else if (count == 8 && strncmp(features, "vfpv3d16", 8) == 0)
+            flags |= HWCAP_VFPv3D16;
+        else if (count == 5 && strncmp(features, "vfpv4", 5) == 0)
+            flags |= HWCAP_VFPv4;
+        else if (count == 5 && strncmp(features, "idiva", 5) == 0)
+            flags |= HWCAP_IDIVA;
+        else if (count == 5 && strncmp(features, "idivt", 5) == 0)
+            flags |= HWCAP_IDIVT;
+        else if (count == 6 && strncmp(features, "vfpd32", 6) == 0)
+            flags |= HWCAP_VFPD32;
+        else if (count == 5 && strncmp(features, "armv7", 5) == 0)
+            flags |= HWCAP_ARMv7;
+        else if (count == 5 && strncmp(features, "align", 5) == 0)
+            flags |= HWCAP_ALIGNMENT_FAULT | HWCAP_FIXUP_FAULT;
+#if defined(JS_SIMULATOR_ARM)
+        else if (count == 7 && strncmp(features, "nofixup", 7) == 0)
+            fixupAlignmentFault = false;
+        else if (count == 6 && strncmp(features, "hardfp", 6) == 0)
+            flags |= HWCAP_USE_HARDFP_ABI;
+#endif
+        else if (override)
+            fprintf(stderr, "Warning: unexpected ARM feature at: %s\n", features);
+        features = end;
+    }
+
+    if (!fixupAlignmentFault)
+        flags &= ~HWCAP_FIXUP_FAULT;
+
+    return flags;
+}
+
+static uint32_t
+CanonicalizeARMHwCapFlags(uint32_t flags)
+{
+    // Canonicalize the flags. These rules are also applied to the features
+    // supplied for simulation.
+
+    // The VFPv3 feature is expected when the VFPv3D16 is reported, but add it
+    // just in case of a kernel difference in feature reporting.
+    if (flags & HWCAP_VFPv3D16)
+        flags |= HWCAP_VFPv3;
+
+    // If VFPv3 or Neon is supported then this must be an ARMv7.
+    if (flags & (HWCAP_VFPv3 | HWCAP_NEON))
+        flags |= HWCAP_ARMv7;
+
+    // Some old kernels report VFP and not VFPv3, but if ARMv7 then it must be
+    // VFPv3.
+    if (flags & HWCAP_VFP && flags & HWCAP_ARMv7)
+        flags |= HWCAP_VFPv3;
+
+    // Older kernels do not implement the HWCAP_VFPD32 flag.
+    if ((flags & HWCAP_VFPv3) && !(flags & HWCAP_VFPv3D16))
+        flags |= HWCAP_VFPD32;
+
+    return flags;
+}
+
+volatile bool forceDoubleCacheFlush = false;
+
+bool
+ForceDoubleCacheFlush() {
+    return forceDoubleCacheFlush;
+}
+
+// The override flags parsed from the ARMHWCAP environment variable or from the
+// --arm-hwcap js shell argument.
+volatile uint32_t armHwCapFlags = HWCAP_UNINITIALIZED;
+
+bool
+ParseARMHwCapFlags(const char* armHwCap)
+{
+    uint32_t flags = 0;
+
+    if (!armHwCap)
+        return false;
+
+    if (strstr(armHwCap, "help")) {
+        fflush(NULL);
+        printf(
+               "\n"
+               "usage: ARMHWCAP=option,option,option,... where options can be:\n"
+               "\n"
+               "  vfp      \n"
+               "  neon     \n"
+               "  vfpv3    \n"
+               "  vfpv3d16 \n"
+               "  vfpv4    \n"
+               "  idiva    \n"
+               "  idivt    \n"
+               "  vfpd32   \n"
+               "  armv7    \n"
+               "  align    - unaligned accesses will trap and be emulated\n"
+#ifdef JS_SIMULATOR_ARM
+               "  nofixup  - disable emulation of unaligned accesses\n"
+               "  hardfp   \n"
+#endif
+               "\n"
+               );
+        exit(0);
+        /*NOTREACHED*/
+    }
+
+    flags = ParseARMCpuFeatures(armHwCap, /* override = */ true);
+
+#ifdef JS_CODEGEN_ARM_HARDFP
+    flags |= HWCAP_USE_HARDFP_ABI;
+#endif
+
+    armHwCapFlags = CanonicalizeARMHwCapFlags(flags);
+    JitSpew(JitSpew_Codegen, "ARM HWCAP: 0x%x\n", armHwCapFlags);
+    return true;
+}
+
+void
+InitARMFlags()
+{
+    uint32_t flags = 0;
+
+    if (armHwCapFlags != HWCAP_UNINITIALIZED)
+        return;
+
+    const char* env = getenv("ARMHWCAP");
+    if (ParseARMHwCapFlags(env))
+        return;
+
+#ifdef JS_SIMULATOR_ARM
+    // HWCAP_FIXUP_FAULT is on by default even if HWCAP_ALIGNMENT_FAULT is
+    // not on by default, because some memory access instructions always fault.
+    // Notably, this is true for floating point accesses.
+    flags = HWCAP_ARMv7 | HWCAP_VFP | HWCAP_VFPv3 | HWCAP_VFPv4 | HWCAP_NEON | HWCAP_IDIVA
+          | HWCAP_FIXUP_FAULT;
+#else
+
+#if defined(__linux__) || defined(ANDROID)
+    // This includes Android and B2G.
+    bool readAuxv = false;
+    int fd = open("/proc/self/auxv", O_RDONLY);
+    if (fd > 0) {
+        struct { uint32_t a_type; uint32_t a_val; } aux;
+        while (read(fd, &aux, sizeof(aux))) {
+            if (aux.a_type == AT_HWCAP) {
+                flags = aux.a_val;
+                readAuxv = true;
+                break;
+            }
+        }
+        close(fd);
+    }
+
+    FILE* fp = fopen("/proc/cpuinfo", "r");
+    if (fp) {
+        char buf[1024];
+        memset(buf, 0, sizeof(buf));
+        size_t len = fread(buf, sizeof(char), sizeof(buf) - 1, fp);
+        fclose(fp);
+        buf[len] = '\0';
+
+        // Read the cpuinfo Features if the auxv is not available.
+        if (!readAuxv) {
+            char* featureList = strstr(buf, "Features");
+            if (featureList) {
+                if (char* featuresEnd = strstr(featureList, "\n"))
+                    *featuresEnd = '\0';
+                flags = ParseARMCpuFeatures(featureList + 8);
+            }
+            if (strstr(buf, "ARMv7"))
+                flags |= HWCAP_ARMv7;
+        }
+
+        // The exynos7420 cpu (EU galaxy S6 (Note)) has a bug where sometimes
+        // flushing doesn't invalidate the instruction cache. As a result we force
+        // it by calling the cacheFlush twice on different start addresses.
+        char* exynos7420 = strstr(buf, "Exynos7420");
+        if (exynos7420)
+            forceDoubleCacheFlush = true;
+    }
+#endif
+
+    // If compiled to use specialized features then these features can be
+    // assumed to be present otherwise the compiler would fail to run.
+
+#ifdef JS_CODEGEN_ARM_HARDFP
+    // Compiled to use the hardfp ABI.
+    flags |= HWCAP_USE_HARDFP_ABI;
+#endif
+
+#if defined(__VFP_FP__) && !defined(__SOFTFP__)
+    // Compiled to use VFP instructions so assume VFP support.
+    flags |= HWCAP_VFP;
+#endif
+
+#if defined(__ARM_ARCH_7__) || defined (__ARM_ARCH_7A__)
+    // Compiled to use ARMv7 instructions so assume the ARMv7 arch.
+    flags |= HWCAP_ARMv7;
+#endif
+
+#if defined(__APPLE__)
+    #if defined(__ARM_NEON__)
+        flags |= HWCAP_NEON;
+    #endif
+    #if defined(__ARMVFPV3__)
+        flags |= HWCAP_VFPv3 | HWCAP_VFPD32
+    #endif
+#endif
+
+#endif // JS_SIMULATOR_ARM
+
+    armHwCapFlags = CanonicalizeARMHwCapFlags(flags);
+
+    JitSpew(JitSpew_Codegen, "ARM HWCAP: 0x%x\n", armHwCapFlags);
+    return;
+}
+
+uint32_t
+GetARMFlags()
+{
+    MOZ_ASSERT(armHwCapFlags != HWCAP_UNINITIALIZED);
+    return armHwCapFlags;
+}
+
+bool HasARMv7()
+{
+    MOZ_ASSERT(armHwCapFlags != HWCAP_UNINITIALIZED);
+    return armHwCapFlags & HWCAP_ARMv7;
+}
+
+bool HasMOVWT()
+{
+    MOZ_ASSERT(armHwCapFlags != HWCAP_UNINITIALIZED);
+    return armHwCapFlags & HWCAP_ARMv7;
+}
+
+bool HasLDSTREXBHD()
+{
+    // These are really available from ARMv6K and later, but why bother?
+    MOZ_ASSERT(armHwCapFlags != HWCAP_UNINITIALIZED);
+    return armHwCapFlags & HWCAP_ARMv7;
+}
+
+bool HasDMBDSBISB()
+{
+    MOZ_ASSERT(armHwCapFlags != HWCAP_UNINITIALIZED);
+    return armHwCapFlags & HWCAP_ARMv7;
+}
+
+bool HasVFPv3()
+{
+    MOZ_ASSERT(armHwCapFlags != HWCAP_UNINITIALIZED);
+    return armHwCapFlags & HWCAP_VFPv3;
+}
+
+bool HasVFP()
+{
+    MOZ_ASSERT(armHwCapFlags != HWCAP_UNINITIALIZED);
+    return armHwCapFlags & HWCAP_VFP;
+}
+
+bool Has32DP()
+{
+    MOZ_ASSERT(armHwCapFlags != HWCAP_UNINITIALIZED);
+    return armHwCapFlags & HWCAP_VFPD32;
+}
+
+bool HasIDIV()
+{
+    MOZ_ASSERT(armHwCapFlags != HWCAP_UNINITIALIZED);
+    return armHwCapFlags & HWCAP_IDIVA;
+}
+
+// This is defined in the header and inlined when not using the simulator.
+#ifdef JS_SIMULATOR_ARM
+bool UseHardFpABI()
+{
+    MOZ_ASSERT(armHwCapFlags != HWCAP_UNINITIALIZED);
+    return armHwCapFlags & HWCAP_USE_HARDFP_ABI;
+}
+#endif
+
+Registers::Code
+Registers::FromName(const char* name)
+{
+    // Check for some register aliases first.
+    if (strcmp(name, "ip") == 0)
+        return ip;
+    if (strcmp(name, "r13") == 0)
+        return r13;
+    if (strcmp(name, "lr") == 0)
+        return lr;
+    if (strcmp(name, "r15") == 0)
+        return r15;
+
+    for (size_t i = 0; i < Total; i++) {
+        if (strcmp(GetName(i), name) == 0)
+            return Code(i);
+    }
+
+    return Invalid;
+}
+
+FloatRegisters::Code
+FloatRegisters::FromName(const char* name)
+{
+    for (size_t i = 0; i < TotalSingle; ++i) {
+        if (strcmp(GetSingleName(Encoding(i)), name) == 0)
+            return VFPRegister(i, VFPRegister::Single).code();
+    }
+    for (size_t i = 0; i < TotalDouble; ++i) {
+        if (strcmp(GetDoubleName(Encoding(i)), name) == 0)
+            return VFPRegister(i, VFPRegister::Double).code();
+    }
+
+    return Invalid;
+}
+
+FloatRegisterSet
+VFPRegister::ReduceSetForPush(const FloatRegisterSet& s)
+{
+    LiveFloatRegisterSet mod;
+    for (FloatRegisterIterator iter(s); iter.more(); ++iter) {
+        if ((*iter).isSingle()) {
+            // Add in just this float.
+            mod.addUnchecked(*iter);
+        } else if ((*iter).id() < 16) {
+            // A double with an overlay, add in both floats.
+            mod.addUnchecked((*iter).singleOverlay(0));
+            mod.addUnchecked((*iter).singleOverlay(1));
+        } else {
+            // Add in the lone double in the range 16-31.
+            mod.addUnchecked(*iter);
+        }
+    }
+    return mod.set();
+}
+
+uint32_t
+VFPRegister::GetPushSizeInBytes(const FloatRegisterSet& s)
+{
+    FloatRegisterSet ss = s.reduceSetForPush();
+    uint64_t bits = ss.bits();
+    uint32_t ret = mozilla::CountPopulation32(bits&0xffffffff) * sizeof(float);
+    ret +=  mozilla::CountPopulation32(bits >> 32) * sizeof(double);
+    return ret;
+}
+uint32_t
+VFPRegister::getRegisterDumpOffsetInBytes()
+{
+    if (isSingle())
+        return id() * sizeof(float);
+    if (isDouble())
+        return id() * sizeof(double);
+    MOZ_CRASH("not Single or Double");
+}
+
+uint32_t
+FloatRegisters::ActualTotalPhys()
+{
+    if (Has32DP())
+        return 32;
+    return 16;
+}
+
+
+} // namespace jit
+} // namespace js
+
diff --git a/js/src/jit/arm/Architecture-arm.h b/js/src/jit/arm/Architecture-arm.h
new file mode 100644
index 0000000000..5e3db5ae2d
--- /dev/null
+++ b/js/src/jit/arm/Architecture-arm.h
@@ -0,0 +1,673 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef jit_arm_Architecture_arm_h
+#define jit_arm_Architecture_arm_h
+
+#include "mozilla/MathAlgorithms.h"
+
+#include <limits.h>
+#include <stdint.h>
+
+#include "js/Utility.h"
+
+// GCC versions 4.6 and above define __ARM_PCS_VFP to denote a hard-float
+// ABI target. The iOS toolchain doesn't define anything specific here,
+// but iOS always supports VFP.
+#if defined(__ARM_PCS_VFP) || defined(XP_IOS)
+#define JS_CODEGEN_ARM_HARDFP
+#endif
+
+namespace js {
+namespace jit {
+
+// In bytes: slots needed for potential memory->memory move spills.
+//   +8 for cycles
+//   +4 for gpr spills
+//   +8 for double spills
+static const uint32_t ION_FRAME_SLACK_SIZE   = 20;
+
+// These offsets are specific to nunboxing, and capture offsets into the
+// components of a js::Value.
+static const int32_t NUNBOX32_TYPE_OFFSET    = 4;
+static const int32_t NUNBOX32_PAYLOAD_OFFSET = 0;
+
+static const uint32_t ShadowStackSpace = 0;
+
+// How far forward/back can a jump go? Provide a generous buffer for thunks.
+static const uint32_t JumpImmediateRange = 25 * 1024 * 1024;
+
+////
+// These offsets are related to bailouts.
+////
+
+// Size of each bailout table entry. On arm, this is presently a single call
+// (which is wrong!). The call clobbers lr.
+// For now, I've dealt with this by ensuring that we never allocate to lr. It
+// should probably be 8 bytes, a mov of an immediate into r12 (not allocated
+// presently, or ever) followed by a branch to the apropriate code.
+static const uint32_t BAILOUT_TABLE_ENTRY_SIZE    = 4;
+
+class Registers
+{
+  public:
+    enum RegisterID {
+        r0 = 0,
+        r1,
+        r2,
+        r3,
+        S0 = r3,
+        r4,
+        r5,
+        r6,
+        r7,
+        r8,
+        S1 = r8,
+        r9,
+        r10,
+        r11,
+        r12,
+        ip = r12,
+        r13,
+        sp = r13,
+        r14,
+        lr = r14,
+        r15,
+        pc = r15,
+        invalid_reg
+    };
+    typedef uint8_t Code;
+    typedef RegisterID Encoding;
+
+    // Content spilled during bailouts.
+    union RegisterContent {
+        uintptr_t r;
+    };
+
+    static const char* GetName(Code code) {
+        MOZ_ASSERT(code < Total);
+        static const char * const Names[] = { "r0", "r1", "r2", "r3", "r4", "r5", "r6", "r7",
+                                              "r8", "r9", "r10", "r11", "r12", "sp", "r14", "pc"};
+        return Names[code];
+    }
+    static const char* GetName(Encoding i) {
+        return GetName(Code(i));
+    }
+
+    static Code FromName(const char* name);
+
+    static const Encoding StackPointer = sp;
+    static const Encoding Invalid = invalid_reg;
+
+    static const uint32_t Total = 16;
+    static const uint32_t Allocatable = 13;
+
+    typedef uint32_t SetType;
+
+    static const SetType AllMask = (1 << Total) - 1;
+    static const SetType ArgRegMask = (1 << r0) | (1 << r1) | (1 << r2) | (1 << r3);
+
+    static const SetType VolatileMask =
+        (1 << r0) |
+        (1 << r1) |
+        (1 << Registers::r2) |
+        (1 << Registers::r3)
+#if defined(XP_IOS)
+        // per https://developer.apple.com/library/ios/documentation/Xcode/Conceptual/iPhoneOSABIReference/Articles/ARMv6FunctionCallingConventions.html#//apple_ref/doc/uid/TP40009021-SW4
+        | (1 << Registers::r9)
+#endif
+              ;
+
+    static const SetType NonVolatileMask =
+        (1 << Registers::r4) |
+        (1 << Registers::r5) |
+        (1 << Registers::r6) |
+        (1 << Registers::r7) |
+        (1 << Registers::r8) |
+#if !defined(XP_IOS)
+        (1 << Registers::r9) |
+#endif
+        (1 << Registers::r10) |
+        (1 << Registers::r11) |
+        (1 << Registers::r12) |
+        (1 << Registers::r14);
+
+    static const SetType WrapperMask =
+        VolatileMask |         // = arguments
+        (1 << Registers::r4) | // = outReg
+        (1 << Registers::r5);  // = argBase
+
+    static const SetType SingleByteRegs =
+        VolatileMask | NonVolatileMask;
+
+    static const SetType NonAllocatableMask =
+        (1 << Registers::sp) |
+        (1 << Registers::r12) | // r12 = ip = scratch
+        (1 << Registers::lr) |
+        (1 << Registers::pc);
+
+    // Registers that can be allocated without being saved, generally.
+    static const SetType TempMask = VolatileMask & ~NonAllocatableMask;
+
+    // Registers returned from a JS -> JS call.
+    static const SetType JSCallMask =
+        (1 << Registers::r2) |
+        (1 << Registers::r3);
+
+    // Registers returned from a JS -> C call.
+    static const SetType CallMask =
+        (1 << Registers::r0) |
+        (1 << Registers::r1);  // Used for double-size returns.
+
+    static const SetType AllocatableMask = AllMask & ~NonAllocatableMask;
+
+    static uint32_t SetSize(SetType x) {
+        static_assert(sizeof(SetType) == 4, "SetType must be 32 bits");
+        return mozilla::CountPopulation32(x);
+    }
+    static uint32_t FirstBit(SetType x) {
+        return mozilla::CountTrailingZeroes32(x);
+    }
+    static uint32_t LastBit(SetType x) {
+        return 31 - mozilla::CountLeadingZeroes32(x);
+    }
+};
+
+// Smallest integer type that can hold a register bitmask.
+typedef uint16_t PackedRegisterMask;
+typedef uint16_t PackedRegisterMask;
+
+class FloatRegisters
+{
+  public:
+    enum FPRegisterID {
+        s0,
+        s1,
+        s2,
+        s3,
+        s4,
+        s5,
+        s6,
+        s7,
+        s8,
+        s9,
+        s10,
+        s11,
+        s12,
+        s13,
+        s14,
+        s15,
+        s16,
+        s17,
+        s18,
+        s19,
+        s20,
+        s21,
+        s22,
+        s23,
+        s24,
+        s25,
+        s26,
+        s27,
+        s28,
+        s29,
+        s30,
+        s31,
+        d0,
+        d1,
+        d2,
+        d3,
+        d4,
+        d5,
+        d6,
+        d7,
+        d8,
+        d9,
+        d10,
+        d11,
+        d12,
+        d13,
+        d14,
+        d15,
+        d16,
+        d17,
+        d18,
+        d19,
+        d20,
+        d21,
+        d22,
+        d23,
+        d24,
+        d25,
+        d26,
+        d27,
+        d28,
+        d29,
+        d30,
+        d31,
+        invalid_freg
+    };
+
+    typedef uint32_t Code;
+    typedef FPRegisterID Encoding;
+
+    // Content spilled during bailouts.
+    union RegisterContent {
+        double d;
+    };
+
+    static const char* GetDoubleName(Encoding code) {
+        static const char * const Names[] = { "d0", "d1", "d2", "d3", "d4", "d5", "d6", "d7",
+                                              "d8", "d9", "d10", "d11", "d12", "d13", "d14", "d15",
+                                              "d16", "d17", "d18", "d19", "d20", "d21", "d22", "d23",
+                                              "d24", "d25", "d26", "d27", "d28", "d29", "d30", "d31"};
+        return Names[code];
+    }
+    static const char* GetSingleName(Encoding code) {
+        static const char * const Names[] = { "s0", "s1", "s2", "s3", "s4", "s5", "s6", "s7",
+                                              "s8", "s9", "s10", "s11", "s12", "s13", "s14", "s15",
+                                              "s16", "s17", "s18", "s19", "s20", "s21", "s22", "s23",
+                                              "s24", "s25", "s26", "s27", "s28", "s29", "s30", "s31"};
+        return Names[code];
+    }
+
+    static Code FromName(const char* name);
+
+    static const Encoding Invalid = invalid_freg;
+    static const uint32_t Total = 48;
+    static const uint32_t TotalDouble = 16;
+    static const uint32_t TotalSingle = 32;
+    static const uint32_t Allocatable = 45;
+    // There are only 32 places that we can put values.
+    static const uint32_t TotalPhys = 32;
+    static uint32_t ActualTotalPhys();
+
+    typedef uint64_t SetType;
+    static const SetType AllSingleMask = (1ull << TotalSingle) - 1;
+    static const SetType AllDoubleMask = ((1ull << TotalDouble) - 1) << TotalSingle;
+    static const SetType AllMask = AllDoubleMask | AllSingleMask;
+
+    // d15 is the ScratchFloatReg.
+    static const SetType NonVolatileDoubleMask =
+         ((1ULL << d8) |
+          (1ULL << d9) |
+          (1ULL << d10) |
+          (1ULL << d11) |
+          (1ULL << d12) |
+          (1ULL << d13) |
+          (1ULL << d14));
+    // s30 and s31 alias d15.
+    static const SetType NonVolatileMask =
+        (NonVolatileDoubleMask |
+         ((1 << s16) |
+          (1 << s17) |
+          (1 << s18) |
+          (1 << s19) |
+          (1 << s20) |
+          (1 << s21) |
+          (1 << s22) |
+          (1 << s23) |
+          (1 << s24) |
+          (1 << s25) |
+          (1 << s26) |
+          (1 << s27) |
+          (1 << s28) |
+          (1 << s29) |
+          (1 << s30)));
+
+    static const SetType VolatileMask = AllMask & ~NonVolatileMask;
+    static const SetType VolatileDoubleMask = AllDoubleMask & ~NonVolatileDoubleMask;
+
+    static const SetType WrapperMask = VolatileMask;
+
+    // d15 is the ARM scratch float register.
+    // s30 and s31 alias d15.
+    static const SetType NonAllocatableMask = ((1ULL << d15)) |
+                                               (1ULL << s30) |
+                                               (1ULL << s31);
+
+    // Registers that can be allocated without being saved, generally.
+    static const SetType TempMask = VolatileMask & ~NonAllocatableMask;
+
+    static const SetType AllocatableMask = AllMask & ~NonAllocatableMask;
+};
+
+template <typename T>
+class TypedRegisterSet;
+
+class VFPRegister
+{
+  public:
+    // What type of data is being stored in this register? UInt / Int are
+    // specifically for vcvt, where we need to know how the data is supposed to
+    // be converted.
+    enum RegType {
+        Single = 0x0,
+        Double = 0x1,
+        UInt   = 0x2,
+        Int    = 0x3
+    };
+
+    typedef FloatRegisters Codes;
+    typedef Codes::Code Code;
+    typedef Codes::Encoding Encoding;
+
+  protected:
+    RegType kind : 2;
+    // ARM doesn't have more than 32 registers. Don't take more bits than we'll
+    // need. Presently, we don't have plans to address the upper and lower
+    // halves of the double registers seprately, so 5 bits should suffice. If we
+    // do decide to address them seprately (vmov, I'm looking at you), we will
+    // likely specify it as a separate field.
+  public:
+    uint32_t code_ : 5;
+  protected:
+    bool _isInvalid : 1;
+    bool _isMissing : 1;
+
+  public:
+    constexpr VFPRegister(uint32_t r, RegType k)
+      : kind(k), code_ (Code(r)), _isInvalid(false), _isMissing(false)
+    { }
+    constexpr VFPRegister()
+      : kind(Double), code_(Code(0)), _isInvalid(true), _isMissing(false)
+    { }
+
+    constexpr VFPRegister(RegType k, uint32_t id, bool invalid, bool missing) :
+        kind(k), code_(Code(id)), _isInvalid(invalid), _isMissing(missing) {
+    }
+
+    explicit constexpr VFPRegister(Code id)
+      : kind(Double), code_(id), _isInvalid(false), _isMissing(false)
+    { }
+    bool operator==(const VFPRegister& other) const {
+        MOZ_ASSERT(!isInvalid());
+        MOZ_ASSERT(!other.isInvalid());
+        return kind == other.kind && code_ == other.code_;
+    }
+
+    bool isSingle() const { return kind == Single; }
+    bool isDouble() const { return kind == Double; }
+    bool isSimd128() const { return false; }
+    bool isFloat() const { return (kind == Double) || (kind == Single); }
+    bool isInt() const { return (kind == UInt) || (kind == Int); }
+    bool isSInt() const { return kind == Int; }
+    bool isUInt() const { return kind == UInt; }
+    bool equiv(const VFPRegister& other) const { return other.kind == kind; }
+    size_t size() const { return (kind == Double) ? 8 : 4; }
+    bool isInvalid() const;
+    bool isMissing() const;
+
+    VFPRegister doubleOverlay(unsigned int which = 0) const;
+    VFPRegister singleOverlay(unsigned int which = 0) const;
+    VFPRegister sintOverlay(unsigned int which = 0) const;
+    VFPRegister uintOverlay(unsigned int which = 0) const;
+
+    VFPRegister asSingle() const { return singleOverlay(); }
+    VFPRegister asDouble() const { return doubleOverlay(); }
+    VFPRegister asSimd128() const { MOZ_CRASH("NYI"); }
+
+    struct VFPRegIndexSplit;
+    VFPRegIndexSplit encode();
+
+    // For serializing values.
+    struct VFPRegIndexSplit {
+        const uint32_t block : 4;
+        const uint32_t bit : 1;
+
+      private:
+        friend VFPRegIndexSplit js::jit::VFPRegister::encode();
+
+        VFPRegIndexSplit(uint32_t block_, uint32_t bit_)
+          : block(block_), bit(bit_)
+        {
+            MOZ_ASSERT(block == block_);
+            MOZ_ASSERT(bit == bit_);
+        }
+    };
+
+    Code code() const {
+        MOZ_ASSERT(!_isInvalid && !_isMissing);
+        // This should only be used in areas where we only have doubles and
+        // singles.
+        MOZ_ASSERT(isFloat());
+        return Code(code_ | (kind << 5));
+    }
+    Encoding encoding() const {
+        MOZ_ASSERT(!_isInvalid && !_isMissing);
+        return Encoding(code_);
+    }
+    uint32_t id() const {
+        return code_;
+    }
+    static VFPRegister FromCode(uint32_t i) {
+        uint32_t code = i & 31;
+        uint32_t kind = i >> 5;
+        return VFPRegister(code, RegType(kind));
+    }
+    bool volatile_() const {
+        if (isDouble())
+            return !!((1 << (code_ >> 1)) & FloatRegisters::VolatileMask);
+        return !!((1 << code_) & FloatRegisters::VolatileMask);
+    }
+    const char* name() const {
+        if (isDouble())
+            return FloatRegisters::GetDoubleName(Encoding(code_));
+        return FloatRegisters::GetSingleName(Encoding(code_));
+    }
+    bool operator != (const VFPRegister& other) const {
+        return other.kind != kind || code_ != other.code_;
+    }
+    bool aliases(const VFPRegister& other) {
+        if (kind == other.kind)
+            return code_ == other.code_;
+        return doubleOverlay() == other.doubleOverlay();
+    }
+    static const int NumAliasedDoubles = 16;
+    uint32_t numAliased() const {
+        if (isDouble()) {
+            if (code_ < NumAliasedDoubles)
+                return 3;
+            return 1;
+        }
+        return 2;
+    }
+
+    // N.B. FloatRegister is an explicit outparam here because msvc-2010
+    // miscompiled it on win64 when the value was simply returned
+    void aliased(uint32_t aliasIdx, VFPRegister* ret) {
+        if (aliasIdx == 0) {
+            *ret = *this;
+            return;
+        }
+        if (isDouble()) {
+            MOZ_ASSERT(code_ < NumAliasedDoubles);
+            MOZ_ASSERT(aliasIdx <= 2);
+            *ret = singleOverlay(aliasIdx - 1);
+            return;
+        }
+        MOZ_ASSERT(aliasIdx == 1);
+        *ret = doubleOverlay(aliasIdx - 1);
+    }
+    uint32_t numAlignedAliased() const {
+        if (isDouble()) {
+            if (code_ < NumAliasedDoubles)
+                return 2;
+            return 1;
+        }
+        // s1 has 0 other aligned aliases, 1 total.
+        // s0 has 1 other aligned aliase, 2 total.
+        return 2 - (code_ & 1);
+    }
+    // |   d0    |
+    // | s0 | s1 |
+    // If we've stored s0 and s1 in memory, we also want to say that d0 is
+    // stored there, but it is only stored at the location where it is aligned
+    // e.g. at s0, not s1.
+    void alignedAliased(uint32_t aliasIdx, VFPRegister* ret) {
+        if (aliasIdx == 0) {
+            *ret = *this;
+            return;
+        }
+        MOZ_ASSERT(aliasIdx == 1);
+        if (isDouble()) {
+            MOZ_ASSERT(code_ < NumAliasedDoubles);
+            *ret = singleOverlay(aliasIdx - 1);
+            return;
+        }
+        MOZ_ASSERT((code_ & 1) == 0);
+        *ret = doubleOverlay(aliasIdx - 1);
+        return;
+    }
+
+    typedef FloatRegisters::SetType SetType;
+
+    // This function is used to ensure that Register set can take all Single
+    // registers, even if we are taking a mix of either double or single
+    // registers.
+    //
+    //   s0.alignedOrDominatedAliasedSet() == s0 | d0.
+    //   s1.alignedOrDominatedAliasedSet() == s1.
+    //   d0.alignedOrDominatedAliasedSet() == s0 | s1 | d0.
+    //
+    // This way the Allocator register set does not have to do any arithmetics
+    // to know if a register is available or not, as we have the following
+    // relations:
+    //
+    //   d0.alignedOrDominatedAliasedSet() ==
+    //       s0.alignedOrDominatedAliasedSet() | s1.alignedOrDominatedAliasedSet()
+    //
+    //   s0.alignedOrDominatedAliasedSet() & s1.alignedOrDominatedAliasedSet() == 0
+    //
+    SetType alignedOrDominatedAliasedSet() const {
+        if (isSingle()) {
+            if (code_ % 2 != 0)
+                return SetType(1) << code_;
+            return (SetType(1) << code_) | (SetType(1) << (32 + code_ / 2));
+        }
+
+        MOZ_ASSERT(isDouble());
+        return (SetType(0b11) << (code_ * 2)) | (SetType(1) << (32 + code_));
+    }
+
+    static uint32_t SetSize(SetType x) {
+        static_assert(sizeof(SetType) == 8, "SetType must be 64 bits");
+        return mozilla::CountPopulation32(x);
+    }
+    static Code FromName(const char* name) {
+        return FloatRegisters::FromName(name);
+    }
+    static TypedRegisterSet<VFPRegister> ReduceSetForPush(const TypedRegisterSet<VFPRegister>& s);
+    static uint32_t GetPushSizeInBytes(const TypedRegisterSet<VFPRegister>& s);
+    uint32_t getRegisterDumpOffsetInBytes();
+    static uint32_t FirstBit(SetType x) {
+        return mozilla::CountTrailingZeroes64(x);
+    }
+    static uint32_t LastBit(SetType x) {
+        return 63 - mozilla::CountLeadingZeroes64(x);
+    }
+
+};
+
+// The only floating point register set that we work with are the VFP Registers.
+typedef VFPRegister FloatRegister;
+
+uint32_t GetARMFlags();
+bool HasARMv7();
+bool HasMOVWT();
+bool HasLDSTREXBHD();           // {LD,ST}REX{B,H,D}
+bool HasDMBDSBISB();            // DMB, DSB, and ISB
+bool HasVFPv3();
+bool HasVFP();
+bool Has32DP();
+bool HasIDIV();
+
+extern volatile uint32_t armHwCapFlags;
+
+// Not part of the HWCAP flag, but we need to know these and these bits are not
+// used. Define these here so that their use can be inlined by the simulator.
+
+// A bit to flag when signaled alignment faults are to be fixed up.
+#define HWCAP_FIXUP_FAULT (1 << 24)
+
+// A bit to flag when the flags are uninitialized, so they can be atomically set.
+#define HWCAP_UNINITIALIZED (1 << 25)
+
+// A bit to flag when alignment faults are enabled and signal.
+#define HWCAP_ALIGNMENT_FAULT (1 << 26)
+
+// A bit to flag the use of the hardfp ABI.
+#define HWCAP_USE_HARDFP_ABI (1 << 27)
+
+// A bit to flag the use of the ARMv7 arch, otherwise ARMv6.
+#define HWCAP_ARMv7 (1 << 28)
+
+// Top three bits are reserved, do not use them.
+
+// Returns true when cpu alignment faults are enabled and signaled, and thus we
+// should ensure loads and stores are aligned.
+inline bool HasAlignmentFault()
+{
+    MOZ_ASSERT(armHwCapFlags != HWCAP_UNINITIALIZED);
+    return armHwCapFlags & HWCAP_ALIGNMENT_FAULT;
+}
+
+#ifdef JS_SIMULATOR_ARM
+// Returns true when cpu alignment faults will be fixed up by the
+// "operating system", which functionality we will emulate.
+inline bool FixupFault()
+{
+    MOZ_ASSERT(armHwCapFlags != HWCAP_UNINITIALIZED);
+    return armHwCapFlags & HWCAP_FIXUP_FAULT;
+}
+#endif
+
+// Arm/D32 has double registers that can NOT be treated as float32 and this
+// requires some dances in lowering.
+inline bool
+hasUnaliasedDouble()
+{
+    return Has32DP();
+}
+
+// On ARM, Dn aliases both S2n and S2n+1, so if you need to convert a float32 to
+// a double as a temporary, you need a temporary double register.
+inline bool
+hasMultiAlias()
+{
+    return true;
+}
+
+bool ParseARMHwCapFlags(const char* armHwCap);
+void InitARMFlags();
+uint32_t GetARMFlags();
+
+// If the simulator is used then the ABI choice is dynamic. Otherwise the ABI is
+// static and useHardFpABI is inlined so that unused branches can be optimized
+// away.
+#ifdef JS_SIMULATOR_ARM
+bool UseHardFpABI();
+#else
+static inline bool UseHardFpABI()
+{
+#if defined(JS_CODEGEN_ARM_HARDFP)
+    return true;
+#else
+    return false;
+#endif
+}
+#endif
+
+bool ForceDoubleCacheFlush();
+
+// In order to handle SoftFp ABI calls, we need to be able to express that we
+// have ABIArg which are represented by pair of general purpose registers.
+#define JS_CODEGEN_REGISTER_PAIR 1
+
+} // namespace jit
+} // namespace js
+
+#endif /* jit_arm_Architecture_arm_h */
diff --git a/js/src/jit/arm/Assembler-arm.cpp b/js/src/jit/arm/Assembler-arm.cpp
new file mode 100644
index 0000000000..2830f06955
--- /dev/null
+++ b/js/src/jit/arm/Assembler-arm.cpp
@@ -0,0 +1,3442 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "jit/arm/Assembler-arm.h"
+
+#include "mozilla/DebugOnly.h"
+#include "mozilla/MathAlgorithms.h"
+
+#include "jscompartment.h"
+#ifdef JS_DISASM_ARM
+#include "jsprf.h"
+#endif
+#include "jsutil.h"
+
+#include "gc/Marking.h"
+#include "jit/arm/disasm/Disasm-arm.h"
+#include "jit/arm/MacroAssembler-arm.h"
+#include "jit/ExecutableAllocator.h"
+#include "jit/JitCompartment.h"
+#include "jit/MacroAssembler.h"
+
+using namespace js;
+using namespace js::jit;
+
+using mozilla::CountLeadingZeroes32;
+
+void dbg_break() {}
+
+// The ABIArgGenerator is used for making system ABI calls and for inter-wasm
+// calls. The system ABI can either be SoftFp or HardFp, and inter-wasm calls
+// are always HardFp calls. The initialization defaults to HardFp, and the ABI
+// choice is made before any system ABI calls with the method "setUseHardFp".
+ABIArgGenerator::ABIArgGenerator()
+  : intRegIndex_(0),
+    floatRegIndex_(0),
+    stackOffset_(0),
+    current_(),
+    useHardFp_(true)
+{ }
+
+// See the "Parameter Passing" section of the "Procedure Call Standard for the
+// ARM Architecture" documentation.
+ABIArg
+ABIArgGenerator::softNext(MIRType type)
+{
+    switch (type) {
+      case MIRType::Int32:
+      case MIRType::Pointer:
+        if (intRegIndex_ == NumIntArgRegs) {
+            current_ = ABIArg(stackOffset_);
+            stackOffset_ += sizeof(uint32_t);
+            break;
+        }
+        current_ = ABIArg(Register::FromCode(intRegIndex_));
+        intRegIndex_++;
+        break;
+      case MIRType::Int64:
+        // Make sure to use an even register index. Increase to next even number
+        // when odd.
+        intRegIndex_ = (intRegIndex_ + 1) & ~1;
+        if (intRegIndex_ == NumIntArgRegs) {
+            // Align the stack on 8 bytes.
+            static const uint32_t align = sizeof(uint64_t) - 1;
+            stackOffset_ = (stackOffset_ + align) & ~align;
+            current_ = ABIArg(stackOffset_);
+            stackOffset_ += sizeof(uint64_t);
+            break;
+        }
+        current_ = ABIArg(Register::FromCode(intRegIndex_), Register::FromCode(intRegIndex_ + 1));
+        intRegIndex_ += 2;
+        break;
+      case MIRType::Float32:
+        if (intRegIndex_ == NumIntArgRegs) {
+            current_ = ABIArg(stackOffset_);
+            stackOffset_ += sizeof(uint32_t);
+            break;
+        }
+        current_ = ABIArg(Register::FromCode(intRegIndex_));
+        intRegIndex_++;
+        break;
+      case MIRType::Double:
+        // Make sure to use an even register index. Increase to next even number
+        // when odd.
+        intRegIndex_ = (intRegIndex_ + 1) & ~1;
+        if (intRegIndex_ == NumIntArgRegs) {
+            // Align the stack on 8 bytes.
+            static const uint32_t align = sizeof(double) - 1;
+            stackOffset_ = (stackOffset_ + align) & ~align;
+            current_ = ABIArg(stackOffset_);
+            stackOffset_ += sizeof(double);
+            break;
+        }
+        current_ = ABIArg(Register::FromCode(intRegIndex_), Register::FromCode(intRegIndex_ + 1));
+        intRegIndex_ += 2;
+        break;
+      default:
+        MOZ_CRASH("Unexpected argument type");
+    }
+
+    return current_;
+}
+
+ABIArg
+ABIArgGenerator::hardNext(MIRType type)
+{
+    switch (type) {
+      case MIRType::Int32:
+      case MIRType::Pointer:
+        if (intRegIndex_ == NumIntArgRegs) {
+            current_ = ABIArg(stackOffset_);
+            stackOffset_ += sizeof(uint32_t);
+            break;
+        }
+        current_ = ABIArg(Register::FromCode(intRegIndex_));
+        intRegIndex_++;
+        break;
+      case MIRType::Int64:
+        // Make sure to use an even register index. Increase to next even number
+        // when odd.
+        intRegIndex_ = (intRegIndex_ + 1) & ~1;
+        if (intRegIndex_ == NumIntArgRegs) {
+            // Align the stack on 8 bytes.
+            static const uint32_t align = sizeof(uint64_t) - 1;
+            stackOffset_ = (stackOffset_ + align) & ~align;
+            current_ = ABIArg(stackOffset_);
+            stackOffset_ += sizeof(uint64_t);
+            break;
+        }
+        current_ = ABIArg(Register::FromCode(intRegIndex_), Register::FromCode(intRegIndex_ + 1));
+        intRegIndex_ += 2;
+        break;
+      case MIRType::Float32:
+        if (floatRegIndex_ == NumFloatArgRegs) {
+            current_ = ABIArg(stackOffset_);
+            stackOffset_ += sizeof(uint32_t);
+            break;
+        }
+        current_ = ABIArg(VFPRegister(floatRegIndex_, VFPRegister::Single));
+        floatRegIndex_++;
+        break;
+      case MIRType::Double:
+        // Double register are composed of 2 float registers, thus we have to
+        // skip any float register which cannot be used in a pair of float
+        // registers in which a double value can be stored.
+        floatRegIndex_ = (floatRegIndex_ + 1) & ~1;
+        if (floatRegIndex_ == NumFloatArgRegs) {
+            static const uint32_t align = sizeof(double) - 1;
+            stackOffset_ = (stackOffset_ + align) & ~align;
+            current_ = ABIArg(stackOffset_);
+            stackOffset_ += sizeof(uint64_t);
+            break;
+        }
+        current_ = ABIArg(VFPRegister(floatRegIndex_ >> 1, VFPRegister::Double));
+        floatRegIndex_ += 2;
+        break;
+      default:
+        MOZ_CRASH("Unexpected argument type");
+    }
+
+    return current_;
+}
+
+ABIArg
+ABIArgGenerator::next(MIRType type)
+{
+    if (useHardFp_)
+        return hardNext(type);
+    return softNext(type);
+}
+
+// Encode a standard register when it is being used as src1, the dest, and an
+// extra register. These should never be called with an InvalidReg.
+uint32_t
+js::jit::RT(Register r)
+{
+    MOZ_ASSERT((r.code() & ~0xf) == 0);
+    return r.code() << 12;
+}
+
+uint32_t
+js::jit::RN(Register r)
+{
+    MOZ_ASSERT((r.code() & ~0xf) == 0);
+    return r.code() << 16;
+}
+
+uint32_t
+js::jit::RD(Register r)
+{
+    MOZ_ASSERT((r.code() & ~0xf) == 0);
+    return r.code() << 12;
+}
+
+uint32_t
+js::jit::RM(Register r)
+{
+    MOZ_ASSERT((r.code() & ~0xf) == 0);
+    return r.code() << 8;
+}
+
+// Encode a standard register when it is being used as src1, the dest, and an
+// extra register. For these, an InvalidReg is used to indicate a optional
+// register that has been omitted.
+uint32_t
+js::jit::maybeRT(Register r)
+{
+    if (r == InvalidReg)
+        return 0;
+
+    MOZ_ASSERT((r.code() & ~0xf) == 0);
+    return r.code() << 12;
+}
+
+uint32_t
+js::jit::maybeRN(Register r)
+{
+    if (r == InvalidReg)
+        return 0;
+
+    MOZ_ASSERT((r.code() & ~0xf) == 0);
+    return r.code() << 16;
+}
+
+uint32_t
+js::jit::maybeRD(Register r)
+{
+    if (r == InvalidReg)
+        return 0;
+
+    MOZ_ASSERT((r.code() & ~0xf) == 0);
+    return r.code() << 12;
+}
+
+Register
+js::jit::toRD(Instruction i)
+{
+    return Register::FromCode((i.encode() >> 12) & 0xf);
+}
+Register
+js::jit::toR(Instruction i)
+{
+    return Register::FromCode(i.encode() & 0xf);
+}
+
+Register
+js::jit::toRM(Instruction i)
+{
+    return Register::FromCode((i.encode() >> 8) & 0xf);
+}
+
+Register
+js::jit::toRN(Instruction i)
+{
+    return Register::FromCode((i.encode() >> 16) & 0xf);
+}
+
+uint32_t
+js::jit::VD(VFPRegister vr)
+{
+    if (vr.isMissing())
+        return 0;
+
+    // Bits 15,14,13,12, 22.
+    VFPRegister::VFPRegIndexSplit s = vr.encode();
+    return s.bit << 22 | s.block << 12;
+}
+uint32_t
+js::jit::VN(VFPRegister vr)
+{
+    if (vr.isMissing())
+        return 0;
+
+    // Bits 19,18,17,16, 7.
+    VFPRegister::VFPRegIndexSplit s = vr.encode();
+    return s.bit << 7 | s.block << 16;
+}
+uint32_t
+js::jit::VM(VFPRegister vr)
+{
+    if (vr.isMissing())
+        return 0;
+
+    // Bits 5, 3,2,1,0.
+    VFPRegister::VFPRegIndexSplit s = vr.encode();
+    return s.bit << 5 | s.block;
+}
+
+VFPRegister::VFPRegIndexSplit
+jit::VFPRegister::encode()
+{
+    MOZ_ASSERT(!_isInvalid);
+
+    switch (kind) {
+      case Double:
+        return VFPRegIndexSplit(code_ & 0xf, code_ >> 4);
+      case Single:
+        return VFPRegIndexSplit(code_ >> 1, code_ & 1);
+      default:
+        // VFP register treated as an integer, NOT a gpr.
+        return VFPRegIndexSplit(code_ >> 1, code_ & 1);
+    }
+}
+
+bool
+InstDTR::IsTHIS(const Instruction& i)
+{
+    return (i.encode() & IsDTRMask) == (uint32_t)IsDTR;
+}
+
+InstDTR*
+InstDTR::AsTHIS(const Instruction& i)
+{
+    if (IsTHIS(i))
+        return (InstDTR*)&i;
+    return nullptr;
+}
+
+bool
+InstLDR::IsTHIS(const Instruction& i)
+{
+    return (i.encode() & IsDTRMask) == (uint32_t)IsDTR;
+}
+
+InstLDR*
+InstLDR::AsTHIS(const Instruction& i)
+{
+    if (IsTHIS(i))
+        return (InstLDR*)&i;
+    return nullptr;
+}
+
+InstNOP*
+InstNOP::AsTHIS(Instruction& i)
+{
+    if (IsTHIS(i))
+        return (InstNOP*)&i;
+    return nullptr;
+}
+
+bool
+InstNOP::IsTHIS(const Instruction& i)
+{
+    return (i.encode() & 0x0fffffff) == NopInst;
+}
+
+bool
+InstBranchReg::IsTHIS(const Instruction& i)
+{
+    return InstBXReg::IsTHIS(i) || InstBLXReg::IsTHIS(i);
+}
+
+InstBranchReg*
+InstBranchReg::AsTHIS(const Instruction& i)
+{
+    if (IsTHIS(i))
+        return (InstBranchReg*)&i;
+    return nullptr;
+}
+void
+InstBranchReg::extractDest(Register* dest)
+{
+    *dest = toR(*this);
+}
+bool
+InstBranchReg::checkDest(Register dest)
+{
+    return dest == toR(*this);
+}
+
+bool
+InstBranchImm::IsTHIS(const Instruction& i)
+{
+    return InstBImm::IsTHIS(i) || InstBLImm::IsTHIS(i);
+}
+
+InstBranchImm*
+InstBranchImm::AsTHIS(const Instruction& i)
+{
+    if (IsTHIS(i))
+        return (InstBranchImm*)&i;
+    return nullptr;
+}
+
+void
+InstBranchImm::extractImm(BOffImm* dest)
+{
+    *dest = BOffImm(*this);
+}
+
+bool
+InstBXReg::IsTHIS(const Instruction& i)
+{
+    return (i.encode() & IsBRegMask) == IsBX;
+}
+
+InstBXReg*
+InstBXReg::AsTHIS(const Instruction& i)
+{
+    if (IsTHIS(i))
+        return (InstBXReg*)&i;
+    return nullptr;
+}
+
+bool
+InstBLXReg::IsTHIS(const Instruction& i)
+{
+    return (i.encode() & IsBRegMask) == IsBLX;
+
+}
+InstBLXReg*
+InstBLXReg::AsTHIS(const Instruction& i)
+{
+    if (IsTHIS(i))
+        return (InstBLXReg*)&i;
+    return nullptr;
+}
+
+bool
+InstBImm::IsTHIS(const Instruction& i)
+{
+    return (i.encode () & IsBImmMask) == IsB;
+}
+InstBImm*
+InstBImm::AsTHIS(const Instruction& i)
+{
+    if (IsTHIS(i))
+        return (InstBImm*)&i;
+    return nullptr;
+}
+
+bool
+InstBLImm::IsTHIS(const Instruction& i)
+{
+    return (i.encode () & IsBImmMask) == IsBL;
+
+}
+InstBLImm*
+InstBLImm::AsTHIS(const Instruction& i)
+{
+    if (IsTHIS(i))
+        return (InstBLImm*)&i;
+    return nullptr;
+}
+
+bool
+InstMovWT::IsTHIS(Instruction& i)
+{
+    return  InstMovW::IsTHIS(i) || InstMovT::IsTHIS(i);
+}
+InstMovWT*
+InstMovWT::AsTHIS(Instruction& i)
+{
+    if (IsTHIS(i))
+        return (InstMovWT*)&i;
+    return nullptr;
+}
+
+void
+InstMovWT::extractImm(Imm16* imm)
+{
+    *imm = Imm16(*this);
+}
+bool
+InstMovWT::checkImm(Imm16 imm)
+{
+    return imm.decode() == Imm16(*this).decode();
+}
+
+void
+InstMovWT::extractDest(Register* dest)
+{
+    *dest = toRD(*this);
+}
+bool
+InstMovWT::checkDest(Register dest)
+{
+    return dest == toRD(*this);
+}
+
+bool
+InstMovW::IsTHIS(const Instruction& i)
+{
+    return (i.encode() & IsWTMask) == IsW;
+}
+
+InstMovW*
+InstMovW::AsTHIS(const Instruction& i)
+{
+    if (IsTHIS(i))
+        return (InstMovW*)&i;
+    return nullptr;
+}
+InstMovT*
+InstMovT::AsTHIS(const Instruction& i)
+{
+    if (IsTHIS(i))
+        return (InstMovT*)&i;
+    return nullptr;
+}
+
+bool
+InstMovT::IsTHIS(const Instruction& i)
+{
+    return (i.encode() & IsWTMask) == IsT;
+}
+
+InstALU*
+InstALU::AsTHIS(const Instruction& i)
+{
+    if (IsTHIS(i))
+        return (InstALU*)&i;
+    return nullptr;
+}
+bool
+InstALU::IsTHIS(const Instruction& i)
+{
+    return (i.encode() & ALUMask) == 0;
+}
+void
+InstALU::extractOp(ALUOp* ret)
+{
+    *ret = ALUOp(encode() & (0xf << 21));
+}
+bool
+InstALU::checkOp(ALUOp op)
+{
+    ALUOp mine;
+    extractOp(&mine);
+    return mine == op;
+}
+void
+InstALU::extractDest(Register* ret)
+{
+    *ret = toRD(*this);
+}
+bool
+InstALU::checkDest(Register rd)
+{
+    return rd == toRD(*this);
+}
+void
+InstALU::extractOp1(Register* ret)
+{
+    *ret = toRN(*this);
+}
+bool
+InstALU::checkOp1(Register rn)
+{
+    return rn == toRN(*this);
+}
+Operand2
+InstALU::extractOp2()
+{
+    return Operand2(encode());
+}
+
+InstCMP*
+InstCMP::AsTHIS(const Instruction& i)
+{
+    if (IsTHIS(i))
+        return (InstCMP*)&i;
+    return nullptr;
+}
+
+bool
+InstCMP::IsTHIS(const Instruction& i)
+{
+    return InstALU::IsTHIS(i) && InstALU::AsTHIS(i)->checkDest(r0) && InstALU::AsTHIS(i)->checkOp(OpCmp);
+}
+
+InstMOV*
+InstMOV::AsTHIS(const Instruction& i)
+{
+    if (IsTHIS(i))
+        return (InstMOV*)&i;
+    return nullptr;
+}
+
+bool
+InstMOV::IsTHIS(const Instruction& i)
+{
+    return InstALU::IsTHIS(i) && InstALU::AsTHIS(i)->checkOp1(r0) && InstALU::AsTHIS(i)->checkOp(OpMov);
+}
+
+Op2Reg
+Operand2::toOp2Reg() const {
+    return *(Op2Reg*)this;
+}
+
+Imm16::Imm16(Instruction& inst)
+  : lower_(inst.encode() & 0xfff),
+    upper_(inst.encode() >> 16),
+    invalid_(0xfff)
+{ }
+
+Imm16::Imm16(uint32_t imm)
+  : lower_(imm & 0xfff), pad_(0),
+    upper_((imm >> 12) & 0xf),
+    invalid_(0)
+{
+    MOZ_ASSERT(decode() == imm);
+}
+
+Imm16::Imm16()
+  : invalid_(0xfff)
+{ }
+
+void
+jit::PatchJump(CodeLocationJump& jump_, CodeLocationLabel label, ReprotectCode reprotect)
+{
+    // We need to determine if this jump can fit into the standard 24+2 bit
+    // address or if we need a larger branch (or just need to use our pool
+    // entry).
+    Instruction* jump = (Instruction*)jump_.raw();
+    // jumpWithPatch() returns the offset of the jump and never a pool or nop.
+    Assembler::Condition c = jump->extractCond();
+    MOZ_ASSERT(jump->is<InstBranchImm>() || jump->is<InstLDR>());
+
+    int jumpOffset = label.raw() - jump_.raw();
+    if (BOffImm::IsInRange(jumpOffset)) {
+        // This instruction started off as a branch, and will remain one.
+        MaybeAutoWritableJitCode awjc(jump, sizeof(Instruction), reprotect);
+        Assembler::RetargetNearBranch(jump, jumpOffset, c);
+    } else {
+        // This instruction started off as a branch, but now needs to be demoted
+        // to an ldr.
+        uint8_t** slot = reinterpret_cast<uint8_t**>(jump_.jumpTableEntry());
+
+        // Ensure both the branch and the slot are writable.
+        MOZ_ASSERT(uintptr_t(slot) > uintptr_t(jump));
+        size_t size = uintptr_t(slot) - uintptr_t(jump) + sizeof(void*);
+        MaybeAutoWritableJitCode awjc(jump, size, reprotect);
+
+        Assembler::RetargetFarBranch(jump, slot, label.raw(), c);
+    }
+}
+
+void
+Assembler::finish()
+{
+    flush();
+    MOZ_ASSERT(!isFinished);
+    isFinished = true;
+}
+
+bool
+Assembler::asmMergeWith(Assembler& other)
+{
+    flush();
+    other.flush();
+    if (other.oom())
+        return false;
+    if (!AssemblerShared::asmMergeWith(size(), other))
+        return false;
+    return m_buffer.appendBuffer(other.m_buffer);
+}
+
+void
+Assembler::executableCopy(uint8_t* buffer)
+{
+    MOZ_ASSERT(isFinished);
+    m_buffer.executableCopy(buffer);
+    AutoFlushICache::setRange(uintptr_t(buffer), m_buffer.size());
+}
+
+uint32_t
+Assembler::actualIndex(uint32_t idx_) const
+{
+    ARMBuffer::PoolEntry pe(idx_);
+    return m_buffer.poolEntryOffset(pe);
+}
+
+uint8_t*
+Assembler::PatchableJumpAddress(JitCode* code, uint32_t pe_)
+{
+    return code->raw() + pe_;
+}
+
+class RelocationIterator
+{
+    CompactBufferReader reader_;
+    // Offset in bytes.
+    uint32_t offset_;
+
+  public:
+    RelocationIterator(CompactBufferReader& reader)
+      : reader_(reader)
+    { }
+
+    bool read() {
+        if (!reader_.more())
+            return false;
+        offset_ = reader_.readUnsigned();
+        return true;
+    }
+
+    uint32_t offset() const {
+        return offset_;
+    }
+};
+
+template<class Iter>
+const uint32_t*
+Assembler::GetCF32Target(Iter* iter)
+{
+    Instruction* inst1 = iter->cur();
+
+    if (inst1->is<InstBranchImm>()) {
+        // See if we have a simple case, b #offset.
+        BOffImm imm;
+        InstBranchImm* jumpB = inst1->as<InstBranchImm>();
+        jumpB->extractImm(&imm);
+        return imm.getDest(inst1)->raw();
+    }
+
+    if (inst1->is<InstMovW>())
+    {
+        // See if we have the complex case:
+        //  movw r_temp, #imm1
+        //  movt r_temp, #imm2
+        //  bx r_temp
+        // OR
+        //  movw r_temp, #imm1
+        //  movt r_temp, #imm2
+        //  str pc, [sp]
+        //  bx r_temp
+
+        Imm16 targ_bot;
+        Imm16 targ_top;
+        Register temp;
+
+        // Extract both the temp register and the bottom immediate.
+        InstMovW* bottom = inst1->as<InstMovW>();
+        bottom->extractImm(&targ_bot);
+        bottom->extractDest(&temp);
+
+        // Extract the top part of the immediate.
+        Instruction* inst2 = iter->next();
+        MOZ_ASSERT(inst2->is<InstMovT>());
+        InstMovT* top = inst2->as<InstMovT>();
+        top->extractImm(&targ_top);
+
+        // Make sure they are being loaded into the same register.
+        MOZ_ASSERT(top->checkDest(temp));
+
+        // Make sure we're branching to the same register.
+#ifdef DEBUG
+        // A toggled call sometimes has a NOP instead of a branch for the third
+        // instruction. No way to assert that it's valid in that situation.
+        Instruction* inst3 = iter->next();
+        if (!inst3->is<InstNOP>()) {
+            InstBranchReg* realBranch = nullptr;
+            if (inst3->is<InstBranchReg>()) {
+                realBranch = inst3->as<InstBranchReg>();
+            } else {
+                Instruction* inst4 = iter->next();
+                realBranch = inst4->as<InstBranchReg>();
+            }
+            MOZ_ASSERT(realBranch->checkDest(temp));
+        }
+#endif
+
+        uint32_t* dest = (uint32_t*) (targ_bot.decode() | (targ_top.decode() << 16));
+        return dest;
+    }
+
+    if (inst1->is<InstLDR>())
+        return *(uint32_t**) inst1->as<InstLDR>()->dest();
+
+    MOZ_CRASH("unsupported branch relocation");
+}
+
+uintptr_t
+Assembler::GetPointer(uint8_t* instPtr)
+{
+    InstructionIterator iter((Instruction*)instPtr);
+    uintptr_t ret = (uintptr_t)GetPtr32Target(&iter, nullptr, nullptr);
+    return ret;
+}
+
+template<class Iter>
+const uint32_t*
+Assembler::GetPtr32Target(Iter* start, Register* dest, RelocStyle* style)
+{
+    Instruction* load1 = start->cur();
+    Instruction* load2 = start->next();
+
+    if (load1->is<InstMovW>() && load2->is<InstMovT>()) {
+        if (style)
+            *style = L_MOVWT;
+
+        // See if we have the complex case:
+        //  movw r_temp, #imm1
+        //  movt r_temp, #imm2
+
+        Imm16 targ_bot;
+        Imm16 targ_top;
+        Register temp;
+
+        // Extract both the temp register and the bottom immediate.
+        InstMovW* bottom = load1->as<InstMovW>();
+        bottom->extractImm(&targ_bot);
+        bottom->extractDest(&temp);
+
+        // Extract the top part of the immediate.
+        InstMovT* top = load2->as<InstMovT>();
+        top->extractImm(&targ_top);
+
+        // Make sure they are being loaded into the same register.
+        MOZ_ASSERT(top->checkDest(temp));
+
+        if (dest)
+            *dest = temp;
+
+        uint32_t* value = (uint32_t*) (targ_bot.decode() | (targ_top.decode() << 16));
+        return value;
+    }
+
+    if (load1->is<InstLDR>()) {
+        if (style)
+            *style = L_LDR;
+        if (dest)
+            *dest = toRD(*load1);
+        return *(uint32_t**) load1->as<InstLDR>()->dest();
+    }
+
+    MOZ_CRASH("unsupported relocation");
+}
+
+static JitCode*
+CodeFromJump(InstructionIterator* jump)
+{
+    uint8_t* target = (uint8_t*)Assembler::GetCF32Target(jump);
+    return JitCode::FromExecutable(target);
+}
+
+void
+Assembler::TraceJumpRelocations(JSTracer* trc, JitCode* code, CompactBufferReader& reader)
+{
+    RelocationIterator iter(reader);
+    while (iter.read()) {
+        InstructionIterator institer((Instruction*) (code->raw() + iter.offset()));
+        JitCode* child = CodeFromJump(&institer);
+        TraceManuallyBarrieredEdge(trc, &child, "rel32");
+    }
+}
+
+template <class Iter>
+static void
+TraceOneDataRelocation(JSTracer* trc, Iter* iter)
+{
+    Instruction* ins = iter->cur();
+    Register dest;
+    Assembler::RelocStyle rs;
+    const void* prior = Assembler::GetPtr32Target(iter, &dest, &rs);
+    void* ptr = const_cast<void*>(prior);
+
+    // No barrier needed since these are constants.
+    TraceManuallyBarrieredGenericPointerEdge(trc, reinterpret_cast<gc::Cell**>(&ptr),
+                                             "ion-masm-ptr");
+
+    if (ptr != prior) {
+        MacroAssemblerARM::ma_mov_patch(Imm32(int32_t(ptr)), dest, Assembler::Always, rs, ins);
+
+        // L_LDR won't cause any instructions to be updated.
+        if (rs != Assembler::L_LDR) {
+            AutoFlushICache::flush(uintptr_t(ins), 4);
+            AutoFlushICache::flush(uintptr_t(ins->next()), 4);
+        }
+    }
+}
+
+static void
+TraceDataRelocations(JSTracer* trc, uint8_t* buffer, CompactBufferReader& reader)
+{
+    while (reader.more()) {
+        size_t offset = reader.readUnsigned();
+        InstructionIterator iter((Instruction*)(buffer + offset));
+        TraceOneDataRelocation(trc, &iter);
+    }
+}
+
+static void
+TraceDataRelocations(JSTracer* trc, ARMBuffer* buffer, CompactBufferReader& reader)
+{
+    while (reader.more()) {
+        BufferOffset offset(reader.readUnsigned());
+        ARMBuffer::AssemblerBufferInstIterator iter(offset, buffer);
+        TraceOneDataRelocation(trc, &iter);
+    }
+}
+
+void
+Assembler::TraceDataRelocations(JSTracer* trc, JitCode* code, CompactBufferReader& reader)
+{
+    ::TraceDataRelocations(trc, code->raw(), reader);
+}
+
+void
+Assembler::copyJumpRelocationTable(uint8_t* dest)
+{
+    if (jumpRelocations_.length())
+        memcpy(dest, jumpRelocations_.buffer(), jumpRelocations_.length());
+}
+
+void
+Assembler::copyDataRelocationTable(uint8_t* dest)
+{
+    if (dataRelocations_.length())
+        memcpy(dest, dataRelocations_.buffer(), dataRelocations_.length());
+}
+
+void
+Assembler::copyPreBarrierTable(uint8_t* dest)
+{
+    if (preBarriers_.length())
+        memcpy(dest, preBarriers_.buffer(), preBarriers_.length());
+}
+
+void
+Assembler::trace(JSTracer* trc)
+{
+    for (size_t i = 0; i < jumps_.length(); i++) {
+        RelativePatch& rp = jumps_[i];
+        if (rp.kind() == Relocation::JITCODE) {
+            JitCode* code = JitCode::FromExecutable((uint8_t*)rp.target());
+            TraceManuallyBarrieredEdge(trc, &code, "masmrel32");
+            MOZ_ASSERT(code == JitCode::FromExecutable((uint8_t*)rp.target()));
+        }
+    }
+
+    if (dataRelocations_.length()) {
+        CompactBufferReader reader(dataRelocations_);
+        ::TraceDataRelocations(trc, &m_buffer, reader);
+    }
+}
+
+void
+Assembler::processCodeLabels(uint8_t* rawCode)
+{
+    for (size_t i = 0; i < codeLabels_.length(); i++) {
+        CodeLabel label = codeLabels_[i];
+        Bind(rawCode, label.patchAt(), rawCode + label.target()->offset());
+    }
+}
+
+void
+Assembler::writeCodePointer(CodeOffset* label) {
+    BufferOffset off = writeInst(LabelBase::INVALID_OFFSET);
+    label->bind(off.getOffset());
+}
+
+void
+Assembler::Bind(uint8_t* rawCode, CodeOffset* label, const void* address)
+{
+    *reinterpret_cast<const void**>(rawCode + label->offset()) = address;
+}
+
+Assembler::Condition
+Assembler::InvertCondition(Condition cond)
+{
+    const uint32_t ConditionInversionBit = 0x10000000;
+    return Condition(ConditionInversionBit ^ cond);
+}
+
+Assembler::Condition
+Assembler::UnsignedCondition(Condition cond)
+{
+    switch (cond) {
+      case Zero:
+      case NonZero:
+        return cond;
+      case LessThan:
+      case Below:
+        return Below;
+      case LessThanOrEqual:
+      case BelowOrEqual:
+        return BelowOrEqual;
+      case GreaterThan:
+      case Above:
+        return Above;
+      case AboveOrEqual:
+      case GreaterThanOrEqual:
+        return AboveOrEqual;
+      default:
+        MOZ_CRASH("unexpected condition");
+    }
+}
+
+Assembler::Condition
+Assembler::ConditionWithoutEqual(Condition cond)
+{
+    switch (cond) {
+      case LessThan:
+      case LessThanOrEqual:
+          return LessThan;
+      case Below:
+      case BelowOrEqual:
+        return Below;
+      case GreaterThan:
+      case GreaterThanOrEqual:
+        return GreaterThan;
+      case Above:
+      case AboveOrEqual:
+        return Above;
+      default:
+        MOZ_CRASH("unexpected condition");
+    }
+}
+Imm8::TwoImm8mData
+Imm8::EncodeTwoImms(uint32_t imm)
+{
+    // In the ideal case, we are looking for a number that (in binary) looks
+    // like:
+    //   0b((00)*)n_1((00)*)n_2((00)*)
+    //      left  n1   mid  n2
+    //   where both n_1 and n_2 fit into 8 bits.
+    // Since this is being done with rotates, we also need to handle the case
+    // that one of these numbers is in fact split between the left and right
+    // sides, in which case the constant will look like:
+    //   0bn_1a((00)*)n_2((00)*)n_1b
+    //     n1a  mid  n2   rgh    n1b
+    // Also remember, values are rotated by multiples of two, and left, mid or
+    // right can have length zero.
+    uint32_t imm1, imm2;
+    int left = CountLeadingZeroes32(imm) & 0x1E;
+    uint32_t no_n1 = imm & ~(0xff << (24 - left));
+
+    // Not technically needed: this case only happens if we can encode as a
+    // single imm8m. There is a perfectly reasonable encoding in this case, but
+    // we shouldn't encourage people to do things like this.
+    if (no_n1 == 0)
+        return TwoImm8mData();
+
+    int mid = CountLeadingZeroes32(no_n1) & 0x1E;
+    uint32_t no_n2 = no_n1 & ~((0xff << ((24 - mid) & 0x1f)) | 0xff >> ((8 + mid) & 0x1f));
+
+    if (no_n2 == 0) {
+        // We hit the easy case, no wraparound.
+        // Note: a single constant *may* look like this.
+        int imm1shift = left + 8;
+        int imm2shift = mid + 8;
+        imm1 = (imm >> (32 - imm1shift)) & 0xff;
+        if (imm2shift >= 32) {
+            imm2shift = 0;
+            // This assert does not always hold, in fact, this would lead to
+            // some incredibly subtle bugs.
+            // assert((imm & 0xff) == no_n1);
+            imm2 = no_n1;
+        } else {
+            imm2 = ((imm >> (32 - imm2shift)) | (imm << imm2shift)) & 0xff;
+            MOZ_ASSERT( ((no_n1 >> (32 - imm2shift)) | (no_n1 << imm2shift)) ==
+                        imm2);
+        }
+        MOZ_ASSERT((imm1shift & 0x1) == 0);
+        MOZ_ASSERT((imm2shift & 0x1) == 0);
+        return TwoImm8mData(datastore::Imm8mData(imm1, imm1shift >> 1),
+                            datastore::Imm8mData(imm2, imm2shift >> 1));
+    }
+
+    // Either it wraps, or it does not fit. If we initially chopped off more
+    // than 8 bits, then it won't fit.
+    if (left >= 8)
+        return TwoImm8mData();
+
+    int right = 32 - (CountLeadingZeroes32(no_n2) & 30);
+    // All remaining set bits *must* fit into the lower 8 bits.
+    // The right == 8 case should be handled by the previous case.
+    if (right > 8)
+        return TwoImm8mData();
+
+    // Make sure the initial bits that we removed for no_n1 fit into the
+    // 8-(32-right) leftmost bits.
+    if (((imm & (0xff << (24 - left))) << (8 - right)) != 0) {
+        // BUT we may have removed more bits than we needed to for no_n1
+        // 0x04104001 e.g. we can encode 0x104 with a single op, then 0x04000001
+        // with a second, but we try to encode 0x0410000 and find that we need a
+        // second op for 0x4000, and 0x1 cannot be included in the encoding of
+        // 0x04100000.
+        no_n1 = imm & ~((0xff >> (8 - right)) | (0xff << (24 + right)));
+        mid = CountLeadingZeroes32(no_n1) & 30;
+        no_n2 = no_n1  & ~((0xff << ((24 - mid)&31)) | 0xff >> ((8 + mid)&31));
+        if (no_n2 != 0)
+            return TwoImm8mData();
+    }
+
+    // Now assemble all of this information into a two coherent constants it is
+    // a rotate right from the lower 8 bits.
+    int imm1shift = 8 - right;
+    imm1 = 0xff & ((imm << imm1shift) | (imm >> (32 - imm1shift)));
+    MOZ_ASSERT((imm1shift & ~0x1e) == 0);
+    // left + 8 + mid is the position of the leftmost bit of n_2.
+    // We needed to rotate 0x000000ab right by 8 in order to get 0xab000000,
+    // then shift again by the leftmost bit in order to get the constant that we
+    // care about.
+    int imm2shift =  mid + 8;
+    imm2 = ((imm >> (32 - imm2shift)) | (imm << imm2shift)) & 0xff;
+    MOZ_ASSERT((imm1shift & 0x1) == 0);
+    MOZ_ASSERT((imm2shift & 0x1) == 0);
+    return TwoImm8mData(datastore::Imm8mData(imm1, imm1shift >> 1),
+                        datastore::Imm8mData(imm2, imm2shift >> 1));
+}
+
+ALUOp
+jit::ALUNeg(ALUOp op, Register dest, Register scratch, Imm32* imm, Register* negDest)
+{
+    // Find an alternate ALUOp to get the job done, and use a different imm.
+    *negDest = dest;
+    switch (op) {
+      case OpMov:
+        *imm = Imm32(~imm->value);
+        return OpMvn;
+      case OpMvn:
+        *imm = Imm32(~imm->value);
+        return OpMov;
+      case OpAnd:
+        *imm = Imm32(~imm->value);
+        return OpBic;
+      case OpBic:
+        *imm = Imm32(~imm->value);
+        return OpAnd;
+      case OpAdd:
+        *imm = Imm32(-imm->value);
+        return OpSub;
+      case OpSub:
+        *imm = Imm32(-imm->value);
+        return OpAdd;
+      case OpCmp:
+        *imm = Imm32(-imm->value);
+        return OpCmn;
+      case OpCmn:
+        *imm = Imm32(-imm->value);
+        return OpCmp;
+      case OpTst:
+        MOZ_ASSERT(dest == InvalidReg);
+        *imm = Imm32(~imm->value);
+        *negDest = scratch;
+        return OpBic;
+        // orr has orn on thumb2 only.
+      default:
+        return OpInvalid;
+    }
+}
+
+bool
+jit::can_dbl(ALUOp op)
+{
+    // Some instructions can't be processed as two separate instructions such as
+    // and, and possibly add (when we're setting ccodes). There is also some
+    // hilarity with *reading* condition codes. For example, adc dest, src1,
+    // 0xfff; (add with carry) can be split up into adc dest, src1, 0xf00; add
+    // dest, dest, 0xff, since "reading" the condition code increments the
+    // result by one conditionally, that only needs to be done on one of the two
+    // instructions.
+    switch (op) {
+      case OpBic:
+      case OpAdd:
+      case OpSub:
+      case OpEor:
+      case OpOrr:
+        return true;
+      default:
+        return false;
+    }
+}
+
+bool
+jit::condsAreSafe(ALUOp op) {
+    // Even when we are setting condition codes, sometimes we can get away with
+    // splitting an operation into two. For example, if our immediate is
+    // 0x00ff00ff, and the operation is eors we can split this in half, since x
+    // ^ 0x00ff0000 ^ 0x000000ff should set all of its condition codes exactly
+    // the same as x ^ 0x00ff00ff. However, if the operation were adds, we
+    // cannot split this in half. If the source on the add is 0xfff00ff0, the
+    // result sholud be 0xef10ef, but do we set the overflow bit or not?
+    // Depending on which half is performed first (0x00ff0000 or 0x000000ff) the
+    // V bit will be set differently, and *not* updating the V bit would be
+    // wrong. Theoretically, the following should work:
+    //  adds r0, r1, 0x00ff0000;
+    //  addsvs r0, r1, 0x000000ff;
+    //  addvc r0, r1, 0x000000ff;
+    // But this is 3 instructions, and at that point, we might as well use
+    // something else.
+    switch(op) {
+      case OpBic:
+      case OpOrr:
+      case OpEor:
+        return true;
+      default:
+        return false;
+    }
+}
+
+ALUOp
+jit::getDestVariant(ALUOp op)
+{
+    // All of the compare operations are dest-less variants of a standard
+    // operation. Given the dest-less variant, return the dest-ful variant.
+    switch (op) {
+      case OpCmp:
+        return OpSub;
+      case OpCmn:
+        return OpAdd;
+      case OpTst:
+        return OpAnd;
+      case OpTeq:
+        return OpEor;
+      default:
+        return op;
+    }
+}
+
+O2RegImmShift
+jit::O2Reg(Register r) {
+    return O2RegImmShift(r, LSL, 0);
+}
+
+O2RegImmShift
+jit::lsl(Register r, int amt)
+{
+    MOZ_ASSERT(0 <= amt && amt <= 31);
+    return O2RegImmShift(r, LSL, amt);
+}
+
+O2RegImmShift
+jit::lsr(Register r, int amt)
+{
+    MOZ_ASSERT(1 <= amt && amt <= 32);
+    return O2RegImmShift(r, LSR, amt);
+}
+
+O2RegImmShift
+jit::ror(Register r, int amt)
+{
+    MOZ_ASSERT(1 <= amt && amt <= 31);
+    return O2RegImmShift(r, ROR, amt);
+}
+O2RegImmShift
+jit::rol(Register r, int amt)
+{
+    MOZ_ASSERT(1 <= amt && amt <= 31);
+    return O2RegImmShift(r, ROR, 32 - amt);
+}
+
+O2RegImmShift
+jit::asr(Register r, int amt)
+{
+    MOZ_ASSERT(1 <= amt && amt <= 32);
+    return O2RegImmShift(r, ASR, amt);
+}
+
+
+O2RegRegShift
+jit::lsl(Register r, Register amt)
+{
+    return O2RegRegShift(r, LSL, amt);
+}
+
+O2RegRegShift
+jit::lsr(Register r, Register amt)
+{
+    return O2RegRegShift(r, LSR, amt);
+}
+
+O2RegRegShift
+jit::ror(Register r, Register amt)
+{
+    return O2RegRegShift(r, ROR, amt);
+}
+
+O2RegRegShift
+jit::asr(Register r, Register amt)
+{
+    return O2RegRegShift(r, ASR, amt);
+}
+
+static js::jit::DoubleEncoder doubleEncoder;
+
+/* static */ const js::jit::VFPImm js::jit::VFPImm::One(0x3FF00000);
+
+js::jit::VFPImm::VFPImm(uint32_t top)
+{
+    data_ = -1;
+    datastore::Imm8VFPImmData tmp;
+    if (doubleEncoder.lookup(top, &tmp))
+        data_ = tmp.encode();
+}
+
+BOffImm::BOffImm(const Instruction& inst)
+  : data_(inst.encode() & 0x00ffffff)
+{
+}
+
+Instruction*
+BOffImm::getDest(Instruction* src) const
+{
+    // TODO: It is probably worthwhile to verify that src is actually a branch.
+    // NOTE: This does not explicitly shift the offset of the destination left by 2,
+    // since it is indexing into an array of instruction sized objects.
+    return &src[((int32_t(data_) << 8) >> 8) + 2];
+}
+
+const js::jit::DoubleEncoder::DoubleEntry js::jit::DoubleEncoder::table[256] = {
+#include "jit/arm/DoubleEntryTable.tbl"
+};
+
+// VFPRegister implementation
+VFPRegister
+VFPRegister::doubleOverlay(unsigned int which) const
+{
+    MOZ_ASSERT(!_isInvalid);
+    MOZ_ASSERT(which == 0);
+    if (kind != Double)
+        return VFPRegister(code_ >> 1, Double);
+    return *this;
+}
+VFPRegister
+VFPRegister::singleOverlay(unsigned int which) const
+{
+    MOZ_ASSERT(!_isInvalid);
+    if (kind == Double) {
+        // There are no corresponding float registers for d16-d31.
+        MOZ_ASSERT(code_ < 16);
+        MOZ_ASSERT(which < 2);
+        return VFPRegister((code_ << 1) + which, Single);
+    }
+    MOZ_ASSERT(which == 0);
+    return VFPRegister(code_, Single);
+}
+
+VFPRegister
+VFPRegister::sintOverlay(unsigned int which) const
+{
+    MOZ_ASSERT(!_isInvalid);
+    if (kind == Double) {
+        // There are no corresponding float registers for d16-d31.
+        MOZ_ASSERT(code_ < 16);
+        MOZ_ASSERT(which < 2);
+        return VFPRegister((code_ << 1) + which, Int);
+    }
+    MOZ_ASSERT(which == 0);
+    return VFPRegister(code_, Int);
+}
+VFPRegister
+VFPRegister::uintOverlay(unsigned int which) const
+{
+    MOZ_ASSERT(!_isInvalid);
+    if (kind == Double) {
+        // There are no corresponding float registers for d16-d31.
+        MOZ_ASSERT(code_ < 16);
+        MOZ_ASSERT(which < 2);
+        return VFPRegister((code_ << 1) + which, UInt);
+    }
+    MOZ_ASSERT(which == 0);
+    return VFPRegister(code_, UInt);
+}
+
+bool
+VFPRegister::isInvalid() const
+{
+    return _isInvalid;
+}
+
+bool
+VFPRegister::isMissing() const
+{
+    MOZ_ASSERT(!_isInvalid);
+    return _isMissing;
+}
+
+
+bool
+Assembler::oom() const
+{
+    return AssemblerShared::oom() ||
+           m_buffer.oom() ||
+           jumpRelocations_.oom() ||
+           dataRelocations_.oom() ||
+           preBarriers_.oom();
+}
+
+// Size of the instruction stream, in bytes. Including pools. This function
+// expects all pools that need to be placed have been placed. If they haven't
+// then we need to go an flush the pools :(
+size_t
+Assembler::size() const
+{
+    return m_buffer.size();
+}
+// Size of the relocation table, in bytes.
+size_t
+Assembler::jumpRelocationTableBytes() const
+{
+    return jumpRelocations_.length();
+}
+size_t
+Assembler::dataRelocationTableBytes() const
+{
+    return dataRelocations_.length();
+}
+
+size_t
+Assembler::preBarrierTableBytes() const
+{
+    return preBarriers_.length();
+}
+
+// Size of the data table, in bytes.
+size_t
+Assembler::bytesNeeded() const
+{
+    return size() +
+        jumpRelocationTableBytes() +
+        dataRelocationTableBytes() +
+        preBarrierTableBytes();
+}
+
+#ifdef JS_DISASM_ARM
+
+void
+Assembler::spewInst(Instruction* i)
+{
+    disasm::NameConverter converter;
+    disasm::Disassembler dasm(converter);
+    disasm::EmbeddedVector<char, disasm::ReasonableBufferSize> buffer;
+    uint8_t* loc = reinterpret_cast<uint8_t*>(const_cast<uint32_t*>(i->raw()));
+    dasm.InstructionDecode(buffer, loc);
+    printf("   %08x  %s\n", reinterpret_cast<uint32_t>(loc), buffer.start());
+}
+
+// Labels are named as they are encountered by adding names to a
+// table, using the Label address as the key.  This is made tricky by
+// the (memory for) Label objects being reused, but reused label
+// objects are recognizable from being marked as not used or not
+// bound.  See spewResolve().
+//
+// In a number of cases there is no information about the target, and
+// we just end up printing "patchable constant load to PC".  This is
+// true especially for jumps to bailout handlers (which have no
+// names).  See spewData() and its callers.  In some cases (loop back
+// edges) some information about the intended target may be propagated
+// from higher levels, and if so it's printed here.
+
+void
+Assembler::spew(Instruction* i)
+{
+    if (spewDisabled() || !i)
+        return;
+    disasm::NameConverter converter;
+    disasm::Disassembler dasm(converter);
+    disasm::EmbeddedVector<char, disasm::ReasonableBufferSize> buffer;
+    uint8_t* loc = reinterpret_cast<uint8_t*>(const_cast<uint32_t*>(i->raw()));
+    dasm.InstructionDecode(buffer, loc);
+    spew("   %08x  %s", reinterpret_cast<uint32_t>(loc), buffer.start());
+}
+
+void
+Assembler::spewTarget(Label* target)
+{
+    if (spewDisabled())
+        return;
+    spew("                        -> %d%s", spewResolve(target), !target->bound() ? "f" : "");
+}
+
+// If a target label is known, always print that and do not attempt to
+// disassemble the branch operands, as they will often be encoding
+// metainformation (pointers for a chain of jump instructions), and
+// not actual branch targets.
+
+void
+Assembler::spewBranch(Instruction* i, Label* target /* may be nullptr */)
+{
+    if (spewDisabled() || !i)
+        return;
+    disasm::NameConverter converter;
+    disasm::Disassembler dasm(converter);
+    disasm::EmbeddedVector<char, disasm::ReasonableBufferSize> buffer;
+    uint8_t* loc = reinterpret_cast<uint8_t*>(const_cast<uint32_t*>(i->raw()));
+    dasm.InstructionDecode(buffer, loc);
+    char labelBuf[128];
+    labelBuf[0] = 0;
+    if (!target)
+        snprintf(labelBuf, sizeof(labelBuf), "  -> (link-time target)");
+    if (InstBranchImm::IsTHIS(*i)) {
+        InstBranchImm* bimm = InstBranchImm::AsTHIS(*i);
+        BOffImm destOff;
+        bimm->extractImm(&destOff);
+        if (destOff.isInvalid() || target) {
+            // The target information in the instruction is likely garbage, so remove it.
+            // The target label will in any case be printed if we have it.
+            //
+            // The format of the instruction disassembly is [0-9a-f]{8}\s+\S+\s+.*,
+            // where the \S+ string is the opcode.  Strip everything after the opcode,
+            // and attach the label if we have it.
+            int i;
+            for ( i=8 ; i < buffer.length() && buffer[i] == ' ' ; i++ )
+                ;
+            for ( ; i < buffer.length() && buffer[i] != ' ' ; i++ )
+                ;
+            buffer[i] = 0;
+            if (target) {
+                snprintf(labelBuf, sizeof(labelBuf), "  -> %d%s", spewResolve(target),
+                         !target->bound() ? "f" : "");
+                target = nullptr;
+            }
+        }
+    }
+    spew("   %08x  %s%s", reinterpret_cast<uint32_t>(loc), buffer.start(), labelBuf);
+    if (target)
+        spewTarget(target);
+}
+
+void
+Assembler::spewLabel(Label* l)
+{
+    if (spewDisabled())
+        return;
+    spew("                        %d:", spewResolve(l));
+}
+
+void
+Assembler::spewRetarget(Label* label, Label* target)
+{
+    if (spewDisabled())
+        return;
+    spew("                        %d: .retarget -> %d%s",
+         spewResolve(label), spewResolve(target), !target->bound() ? "f" : "");
+}
+
+void
+Assembler::spewData(BufferOffset addr, size_t numInstr, bool loadToPC)
+{
+    if (spewDisabled())
+        return;
+    Instruction* inst = m_buffer.getInstOrNull(addr);
+    if (!inst)
+        return;
+    uint32_t *instr = reinterpret_cast<uint32_t*>(inst);
+    for ( size_t k=0 ; k < numInstr ; k++ ) {
+        spew("   %08x  %08x       (patchable constant load%s)",
+             reinterpret_cast<uint32_t>(instr+k), *(instr+k), loadToPC ? " to PC" : "");
+    }
+}
+
+bool
+Assembler::spewDisabled()
+{
+    return !(JitSpewEnabled(JitSpew_Codegen) || printer_);
+}
+
+void
+Assembler::spew(const char* fmt, ...)
+{
+    va_list args;
+    va_start(args, fmt);
+    spew(fmt, args);
+    va_end(args);
+}
+
+void
+Assembler::spew(const char* fmt, va_list va)
+{
+    if (printer_) {
+        printer_->vprintf(fmt, va);
+        printer_->put("\n");
+    }
+    js::jit::JitSpewVA(js::jit::JitSpew_Codegen, fmt, va);
+}
+
+uint32_t
+Assembler::spewResolve(Label* l)
+{
+    // Note, spewResolve will sometimes return 0 when it is triggered
+    // by the profiler and not by a full disassembly, since in that
+    // case a label can be used or bound but not previously have been
+    // defined.
+    return l->used() || l->bound() ? spewProbe(l) : spewDefine(l);
+}
+
+uint32_t
+Assembler::spewProbe(Label* l)
+{
+    uint32_t key = reinterpret_cast<uint32_t>(l);
+    uint32_t value = 0;
+    spewNodes_.lookup(key, &value);
+    return value;
+}
+
+uint32_t
+Assembler::spewDefine(Label* l)
+{
+    uint32_t key = reinterpret_cast<uint32_t>(l);
+    spewNodes_.remove(key);
+    uint32_t value = spewNext_++;
+    if (!spewNodes_.add(key, value))
+        return 0;
+    return value;
+}
+
+Assembler::SpewNodes::~SpewNodes()
+{
+    Node* p = nodes;
+    while (p) {
+        Node* victim = p;
+        p = p->next;
+        js_free(victim);
+    }
+}
+
+bool
+Assembler::SpewNodes::lookup(uint32_t key, uint32_t* value)
+{
+    for ( Node* p = nodes ; p ; p = p->next ) {
+        if (p->key == key) {
+            *value = p->value;
+            return true;
+        }
+    }
+    return false;
+}
+
+bool
+Assembler::SpewNodes::add(uint32_t key, uint32_t value)
+{
+    Node* node = (Node*)js_malloc(sizeof(Node));
+    if (!node)
+        return false;
+    node->key = key;
+    node->value = value;
+    node->next = nodes;
+    nodes = node;
+    return true;
+}
+
+bool
+Assembler::SpewNodes::remove(uint32_t key)
+{
+    for ( Node* p = nodes, *pp = nullptr ; p ; pp = p, p = p->next ) {
+        if (p->key == key) {
+            if (pp)
+                pp->next = p->next;
+            else
+                nodes = p->next;
+            js_free(p);
+            return true;
+        }
+    }
+    return false;
+}
+
+#endif // JS_DISASM_ARM
+
+// Write a blob of binary into the instruction stream.
+BufferOffset
+Assembler::writeInst(uint32_t x)
+{
+    BufferOffset offs = m_buffer.putInt(x);
+#ifdef JS_DISASM_ARM
+    spew(m_buffer.getInstOrNull(offs));
+#endif
+    return offs;
+}
+
+BufferOffset
+Assembler::writeBranchInst(uint32_t x, Label* documentation)
+{
+    BufferOffset offs = m_buffer.putInt(x, /* markAsBranch = */ true);
+#ifdef JS_DISASM_ARM
+    spewBranch(m_buffer.getInstOrNull(offs), documentation);
+#endif
+    return offs;
+}
+
+// Allocate memory for a branch instruction, it will be overwritten
+// subsequently and should not be disassembled.
+
+BufferOffset
+Assembler::allocBranchInst()
+{
+    return m_buffer.putInt(Always | InstNOP::NopInst, /* markAsBranch = */ true);
+}
+
+void
+Assembler::WriteInstStatic(uint32_t x, uint32_t* dest)
+{
+    MOZ_ASSERT(dest != nullptr);
+    *dest = x;
+}
+
+void
+Assembler::haltingAlign(int alignment)
+{
+    // TODO: Implement a proper halting align.
+    nopAlign(alignment);
+}
+
+void
+Assembler::nopAlign(int alignment)
+{
+    m_buffer.align(alignment);
+}
+
+BufferOffset
+Assembler::as_nop()
+{
+    return writeInst(0xe320f000);
+}
+
+static uint32_t
+EncodeAlu(Register dest, Register src1, Operand2 op2, ALUOp op, SBit s, Assembler::Condition c)
+{
+    return (int)op | (int)s | (int)c | op2.encode() |
+           ((dest == InvalidReg) ? 0 : RD(dest)) |
+           ((src1 == InvalidReg) ? 0 : RN(src1));
+}
+
+BufferOffset
+Assembler::as_alu(Register dest, Register src1, Operand2 op2,
+                  ALUOp op, SBit s, Condition c)
+{
+    return writeInst(EncodeAlu(dest, src1, op2, op, s, c));
+}
+
+BufferOffset
+Assembler::as_mov(Register dest, Operand2 op2, SBit s, Condition c)
+{
+    return as_alu(dest, InvalidReg, op2, OpMov, s, c);
+}
+
+/* static */ void
+Assembler::as_alu_patch(Register dest, Register src1, Operand2 op2, ALUOp op, SBit s,
+                        Condition c, uint32_t* pos)
+{
+    WriteInstStatic(EncodeAlu(dest, src1, op2, op, s, c), pos);
+}
+
+/* static */ void
+Assembler::as_mov_patch(Register dest, Operand2 op2, SBit s, Condition c, uint32_t* pos)
+{
+    as_alu_patch(dest, InvalidReg, op2, OpMov, s, c, pos);
+}
+
+BufferOffset
+Assembler::as_mvn(Register dest, Operand2 op2, SBit s, Condition c)
+{
+    return as_alu(dest, InvalidReg, op2, OpMvn, s, c);
+}
+
+// Logical operations.
+BufferOffset
+Assembler::as_and(Register dest, Register src1, Operand2 op2, SBit s, Condition c)
+{
+    return as_alu(dest, src1, op2, OpAnd, s, c);
+}
+BufferOffset
+Assembler::as_bic(Register dest, Register src1, Operand2 op2, SBit s, Condition c)
+{
+    return as_alu(dest, src1, op2, OpBic, s, c);
+}
+BufferOffset
+Assembler::as_eor(Register dest, Register src1, Operand2 op2, SBit s, Condition c)
+{
+    return as_alu(dest, src1, op2, OpEor, s, c);
+}
+BufferOffset
+Assembler::as_orr(Register dest, Register src1, Operand2 op2, SBit s, Condition c)
+{
+    return as_alu(dest, src1, op2, OpOrr, s, c);
+}
+
+// Mathematical operations.
+BufferOffset
+Assembler::as_adc(Register dest, Register src1, Operand2 op2, SBit s, Condition c)
+{
+    return as_alu(dest, src1, op2, OpAdc, s, c);
+}
+BufferOffset
+Assembler::as_add(Register dest, Register src1, Operand2 op2, SBit s, Condition c)
+{
+    return as_alu(dest, src1, op2, OpAdd, s, c);
+}
+BufferOffset
+Assembler::as_sbc(Register dest, Register src1, Operand2 op2, SBit s, Condition c)
+{
+    return as_alu(dest, src1, op2, OpSbc, s, c);
+}
+BufferOffset
+Assembler::as_sub(Register dest, Register src1, Operand2 op2, SBit s, Condition c)
+{
+    return as_alu(dest, src1, op2, OpSub, s, c);
+}
+BufferOffset
+Assembler::as_rsb(Register dest, Register src1, Operand2 op2, SBit s, Condition c)
+{
+    return as_alu(dest, src1, op2, OpRsb, s, c);
+}
+BufferOffset
+Assembler::as_rsc(Register dest, Register src1, Operand2 op2, SBit s, Condition c)
+{
+    return as_alu(dest, src1, op2, OpRsc, s, c);
+}
+
+// Test operations.
+BufferOffset
+Assembler::as_cmn(Register src1, Operand2 op2, Condition c)
+{
+    return as_alu(InvalidReg, src1, op2, OpCmn, SetCC, c);
+}
+BufferOffset
+Assembler::as_cmp(Register src1, Operand2 op2, Condition c)
+{
+    return as_alu(InvalidReg, src1, op2, OpCmp, SetCC, c);
+}
+BufferOffset
+Assembler::as_teq(Register src1, Operand2 op2, Condition c)
+{
+    return as_alu(InvalidReg, src1, op2, OpTeq, SetCC, c);
+}
+BufferOffset
+Assembler::as_tst(Register src1, Operand2 op2, Condition c)
+{
+    return as_alu(InvalidReg, src1, op2, OpTst, SetCC, c);
+}
+
+static constexpr Register NoAddend = { Registers::pc };
+
+static const int SignExtend = 0x06000070;
+
+enum SignExtend {
+    SxSxtb = 10 << 20,
+    SxSxth = 11 << 20,
+    SxUxtb = 14 << 20,
+    SxUxth = 15 << 20
+};
+
+// Sign extension operations.
+BufferOffset
+Assembler::as_sxtb(Register dest, Register src, int rotate, Condition c)
+{
+    return writeInst((int)c | SignExtend | SxSxtb | RN(NoAddend) | RD(dest) | ((rotate & 3) << 10) | src.code());
+}
+BufferOffset
+Assembler::as_sxth(Register dest, Register src, int rotate, Condition c)
+{
+    return writeInst((int)c | SignExtend | SxSxth | RN(NoAddend) | RD(dest) | ((rotate & 3) << 10) | src.code());
+}
+BufferOffset
+Assembler::as_uxtb(Register dest, Register src, int rotate, Condition c)
+{
+    return writeInst((int)c | SignExtend | SxUxtb | RN(NoAddend) | RD(dest) | ((rotate & 3) << 10) | src.code());
+}
+BufferOffset
+Assembler::as_uxth(Register dest, Register src, int rotate, Condition c)
+{
+    return writeInst((int)c | SignExtend | SxUxth | RN(NoAddend) | RD(dest) | ((rotate & 3) << 10) | src.code());
+}
+
+static uint32_t
+EncodeMovW(Register dest, Imm16 imm, Assembler::Condition c)
+{
+    MOZ_ASSERT(HasMOVWT());
+    return 0x03000000 | c | imm.encode() | RD(dest);
+}
+
+static uint32_t
+EncodeMovT(Register dest, Imm16 imm, Assembler::Condition c)
+{
+    MOZ_ASSERT(HasMOVWT());
+    return 0x03400000 | c | imm.encode() | RD(dest);
+}
+
+// Not quite ALU worthy, but these are useful none the less. These also have
+// the isue of these being formatted completly differently from the standard ALU
+// operations.
+BufferOffset
+Assembler::as_movw(Register dest, Imm16 imm, Condition c)
+{
+    return writeInst(EncodeMovW(dest, imm, c));
+}
+
+/* static */ void
+Assembler::as_movw_patch(Register dest, Imm16 imm, Condition c, Instruction* pos)
+{
+    WriteInstStatic(EncodeMovW(dest, imm, c), (uint32_t*)pos);
+}
+
+BufferOffset
+Assembler::as_movt(Register dest, Imm16 imm, Condition c)
+{
+    return writeInst(EncodeMovT(dest, imm, c));
+}
+
+/* static */ void
+Assembler::as_movt_patch(Register dest, Imm16 imm, Condition c, Instruction* pos)
+{
+    WriteInstStatic(EncodeMovT(dest, imm, c), (uint32_t*)pos);
+}
+
+static const int mull_tag = 0x90;
+
+BufferOffset
+Assembler::as_genmul(Register dhi, Register dlo, Register rm, Register rn,
+                     MULOp op, SBit s, Condition c)
+{
+
+    return writeInst(RN(dhi) | maybeRD(dlo) | RM(rm) | rn.code() | op | s | c | mull_tag);
+}
+BufferOffset
+Assembler::as_mul(Register dest, Register src1, Register src2, SBit s, Condition c)
+{
+    return as_genmul(dest, InvalidReg, src1, src2, OpmMul, s, c);
+}
+BufferOffset
+Assembler::as_mla(Register dest, Register acc, Register src1, Register src2,
+                  SBit s, Condition c)
+{
+    return as_genmul(dest, acc, src1, src2, OpmMla, s, c);
+}
+BufferOffset
+Assembler::as_umaal(Register destHI, Register destLO, Register src1, Register src2, Condition c)
+{
+    return as_genmul(destHI, destLO, src1, src2, OpmUmaal, LeaveCC, c);
+}
+BufferOffset
+Assembler::as_mls(Register dest, Register acc, Register src1, Register src2, Condition c)
+{
+    return as_genmul(dest, acc, src1, src2, OpmMls, LeaveCC, c);
+}
+
+BufferOffset
+Assembler::as_umull(Register destHI, Register destLO, Register src1, Register src2,
+                    SBit s, Condition c)
+{
+    return as_genmul(destHI, destLO, src1, src2, OpmUmull, s, c);
+}
+
+BufferOffset
+Assembler::as_umlal(Register destHI, Register destLO, Register src1, Register src2,
+                    SBit s, Condition c)
+{
+    return as_genmul(destHI, destLO, src1, src2, OpmUmlal, s, c);
+}
+
+BufferOffset
+Assembler::as_smull(Register destHI, Register destLO, Register src1, Register src2,
+                    SBit s, Condition c)
+{
+    return as_genmul(destHI, destLO, src1, src2, OpmSmull, s, c);
+}
+
+BufferOffset
+Assembler::as_smlal(Register destHI, Register destLO, Register src1, Register src2,
+                    SBit s, Condition c)
+{
+    return as_genmul(destHI, destLO, src1, src2, OpmSmlal, s, c);
+}
+
+BufferOffset
+Assembler::as_sdiv(Register rd, Register rn, Register rm, Condition c)
+{
+    return writeInst(0x0710f010 | c | RN(rd) | RM(rm) | rn.code());
+}
+
+BufferOffset
+Assembler::as_udiv(Register rd, Register rn, Register rm, Condition c)
+{
+    return writeInst(0x0730f010 | c | RN(rd) | RM(rm) | rn.code());
+}
+
+BufferOffset
+Assembler::as_clz(Register dest, Register src, Condition c)
+{
+    MOZ_ASSERT(src != pc && dest != pc);
+    return writeInst(RD(dest) | src.code() | c | 0x016f0f10);
+}
+
+// Data transfer instructions: ldr, str, ldrb, strb. Using an int to
+// differentiate between 8 bits and 32 bits is overkill, but meh.
+
+static uint32_t
+EncodeDtr(LoadStore ls, int size, Index mode, Register rt, DTRAddr addr, Assembler::Condition c)
+{
+    MOZ_ASSERT(mode == Offset ||  (rt != addr.getBase() && pc != addr.getBase()));
+    MOZ_ASSERT(size == 32 || size == 8);
+    return 0x04000000 | ls | (size == 8 ? 0x00400000 : 0) | mode | c | RT(rt) | addr.encode();
+}
+
+BufferOffset
+Assembler::as_dtr(LoadStore ls, int size, Index mode, Register rt, DTRAddr addr, Condition c)
+{
+    return writeInst(EncodeDtr(ls, size, mode, rt, addr, c));
+}
+
+/* static */ void
+Assembler::as_dtr_patch(LoadStore ls, int size, Index mode, Register rt, DTRAddr addr, Condition c,
+                        uint32_t* dest)
+{
+    WriteInstStatic(EncodeDtr(ls, size, mode, rt, addr, c), dest);
+}
+
+class PoolHintData
+{
+  public:
+    enum LoadType {
+        // Set 0 to bogus, since that is the value most likely to be
+        // accidentally left somewhere.
+        PoolBOGUS  = 0,
+        PoolDTR    = 1,
+        PoolBranch = 2,
+        PoolVDTR   = 3
+    };
+
+  private:
+    uint32_t   index_    : 16;
+    uint32_t   cond_     : 4;
+    LoadType   loadType_ : 2;
+    uint32_t   destReg_  : 5;
+    uint32_t   destType_ : 1;
+    uint32_t   ONES     : 4;
+
+    static const uint32_t ExpectedOnes = 0xfu;
+
+  public:
+    void init(uint32_t index, Assembler::Condition cond, LoadType lt, Register destReg) {
+        index_ = index;
+        MOZ_ASSERT(index_ == index);
+        cond_ = cond >> 28;
+        MOZ_ASSERT(cond_ == cond >> 28);
+        loadType_ = lt;
+        ONES = ExpectedOnes;
+        destReg_ = destReg.code();
+        destType_ = 0;
+    }
+    void init(uint32_t index, Assembler::Condition cond, LoadType lt, const VFPRegister& destReg) {
+        MOZ_ASSERT(destReg.isFloat());
+        index_ = index;
+        MOZ_ASSERT(index_ == index);
+        cond_ = cond >> 28;
+        MOZ_ASSERT(cond_ == cond >> 28);
+        loadType_ = lt;
+        ONES = ExpectedOnes;
+        destReg_ = destReg.id();
+        destType_ = destReg.isDouble();
+    }
+    Assembler::Condition getCond() const {
+        return Assembler::Condition(cond_ << 28);
+    }
+
+    Register getReg() const {
+        return Register::FromCode(destReg_);
+    }
+    VFPRegister getVFPReg() const {
+        VFPRegister r = VFPRegister(destReg_, destType_ ? VFPRegister::Double : VFPRegister::Single);
+        return r;
+    }
+
+    int32_t getIndex() const {
+        return index_;
+    }
+    void setIndex(uint32_t index) {
+        MOZ_ASSERT(ONES == ExpectedOnes && loadType_ != PoolBOGUS);
+        index_ = index;
+        MOZ_ASSERT(index_ == index);
+    }
+
+    LoadType getLoadType() const {
+        // If this *was* a PoolBranch, but the branch has already been bound
+        // then this isn't going to look like a real poolhintdata, but we still
+        // want to lie about it so everyone knows it *used* to be a branch.
+        if (ONES != ExpectedOnes)
+            return PoolHintData::PoolBranch;
+        return loadType_;
+    }
+
+    bool isValidPoolHint() const {
+        // Most instructions cannot have a condition that is 0xf. Notable
+        // exceptions are blx and the entire NEON instruction set. For the
+        // purposes of pool loads, and possibly patched branches, the possible
+        // instructions are ldr and b, neither of which can have a condition
+        // code of 0xf.
+        return ONES == ExpectedOnes;
+    }
+};
+
+union PoolHintPun
+{
+    PoolHintData phd;
+    uint32_t raw;
+};
+
+// Handles all of the other integral data transferring functions: ldrsb, ldrsh,
+// ldrd, etc. The size is given in bits.
+BufferOffset
+Assembler::as_extdtr(LoadStore ls, int size, bool IsSigned, Index mode,
+                     Register rt, EDtrAddr addr, Condition c)
+{
+    int extra_bits2 = 0;
+    int extra_bits1 = 0;
+    switch(size) {
+      case 8:
+        MOZ_ASSERT(IsSigned);
+        MOZ_ASSERT(ls != IsStore);
+        extra_bits1 = 0x1;
+        extra_bits2 = 0x2;
+        break;
+      case 16:
+        // 'case 32' doesn't need to be handled, it is handled by the default
+        // ldr/str.
+        extra_bits2 = 0x01;
+        extra_bits1 = (ls == IsStore) ? 0 : 1;
+        if (IsSigned) {
+            MOZ_ASSERT(ls != IsStore);
+            extra_bits2 |= 0x2;
+        }
+        break;
+      case 64:
+        extra_bits2 = (ls == IsStore) ? 0x3 : 0x2;
+        extra_bits1 = 0;
+        break;
+      default:
+        MOZ_CRASH("unexpected size in as_extdtr");
+    }
+    return writeInst(extra_bits2 << 5 | extra_bits1 << 20 | 0x90 |
+                     addr.encode() | RT(rt) | mode | c);
+}
+
+BufferOffset
+Assembler::as_dtm(LoadStore ls, Register rn, uint32_t mask,
+                DTMMode mode, DTMWriteBack wb, Condition c)
+{
+    return writeInst(0x08000000 | RN(rn) | ls | mode | mask | c | wb);
+}
+
+// Note, it's possible for markAsBranch and loadToPC to disagree,
+// because some loads to the PC are not necessarily encoding
+// instructions that should be marked as branches: only patchable
+// near branch instructions should be marked.
+
+BufferOffset
+Assembler::allocEntry(size_t numInst, unsigned numPoolEntries,
+                      uint8_t* inst, uint8_t* data, ARMBuffer::PoolEntry* pe,
+                      bool markAsBranch, bool loadToPC)
+{
+    BufferOffset offs = m_buffer.allocEntry(numInst, numPoolEntries, inst, data, pe, markAsBranch);
+    propagateOOM(offs.assigned());
+#ifdef JS_DISASM_ARM
+    spewData(offs, numInst, loadToPC);
+#endif
+    return offs;
+}
+
+// This is also used for instructions that might be resolved into branches,
+// or might not.  If dest==pc then it is effectively a branch.
+
+BufferOffset
+Assembler::as_Imm32Pool(Register dest, uint32_t value, Condition c)
+{
+    PoolHintPun php;
+    php.phd.init(0, c, PoolHintData::PoolDTR, dest);
+    BufferOffset offs = allocEntry(1, 1, (uint8_t*)&php.raw, (uint8_t*)&value, nullptr, false,
+                                   dest == pc);
+    return offs;
+}
+
+/* static */ void
+Assembler::WritePoolEntry(Instruction* addr, Condition c, uint32_t data)
+{
+    MOZ_ASSERT(addr->is<InstLDR>());
+    *addr->as<InstLDR>()->dest() = data;
+    MOZ_ASSERT(addr->extractCond() == c);
+}
+
+BufferOffset
+Assembler::as_BranchPool(uint32_t value, RepatchLabel* label, ARMBuffer::PoolEntry* pe, Condition c,
+                         Label* documentation)
+{
+    PoolHintPun php;
+    php.phd.init(0, c, PoolHintData::PoolBranch, pc);
+    BufferOffset ret = allocEntry(1, 1, (uint8_t*)&php.raw, (uint8_t*)&value, pe,
+                                  /* markAsBranch = */ true, /* loadToPC = */ true);
+    // If this label is already bound, then immediately replace the stub load
+    // with a correct branch.
+    if (label->bound()) {
+        BufferOffset dest(label);
+        BOffImm offset = dest.diffB<BOffImm>(ret);
+        if (offset.isInvalid()) {
+            m_buffer.fail_bail();
+            return ret;
+        }
+        as_b(offset, c, ret);
+    } else if (!oom()) {
+        label->use(ret.getOffset());
+    }
+#ifdef JS_DISASM_ARM
+    if (documentation)
+        spewTarget(documentation);
+#endif
+    return ret;
+}
+
+BufferOffset
+Assembler::as_FImm64Pool(VFPRegister dest, wasm::RawF64 value, Condition c)
+{
+    MOZ_ASSERT(dest.isDouble());
+    PoolHintPun php;
+    php.phd.init(0, c, PoolHintData::PoolVDTR, dest);
+    uint64_t d = value.bits();
+    return allocEntry(1, 2, (uint8_t*)&php.raw, (uint8_t*)&d);
+}
+
+BufferOffset
+Assembler::as_FImm32Pool(VFPRegister dest, wasm::RawF32 value, Condition c)
+{
+    // Insert floats into the double pool as they have the same limitations on
+    // immediate offset. This wastes 4 bytes padding per float. An alternative
+    // would be to have a separate pool for floats.
+    MOZ_ASSERT(dest.isSingle());
+    PoolHintPun php;
+    php.phd.init(0, c, PoolHintData::PoolVDTR, dest);
+    uint32_t f = value.bits();
+    return allocEntry(1, 1, (uint8_t*)&php.raw, (uint8_t*)&f);
+}
+
+// Pool callbacks stuff:
+void
+Assembler::InsertIndexIntoTag(uint8_t* load_, uint32_t index)
+{
+    uint32_t* load = (uint32_t*)load_;
+    PoolHintPun php;
+    php.raw = *load;
+    php.phd.setIndex(index);
+    *load = php.raw;
+}
+
+// patchConstantPoolLoad takes the address of the instruction that wants to be
+// patched, and the address of the start of the constant pool, and figures
+// things out from there.
+void
+Assembler::PatchConstantPoolLoad(void* loadAddr, void* constPoolAddr)
+{
+    PoolHintData data = *(PoolHintData*)loadAddr;
+    uint32_t* instAddr = (uint32_t*) loadAddr;
+    int offset = (char*)constPoolAddr - (char*)loadAddr;
+    switch(data.getLoadType()) {
+      case PoolHintData::PoolBOGUS:
+        MOZ_CRASH("bogus load type!");
+      case PoolHintData::PoolDTR:
+        Assembler::as_dtr_patch(IsLoad, 32, Offset, data.getReg(),
+                                DTRAddr(pc, DtrOffImm(offset+4*data.getIndex() - 8)),
+                                data.getCond(), instAddr);
+        break;
+      case PoolHintData::PoolBranch:
+        // Either this used to be a poolBranch, and the label was already bound,
+        // so it was replaced with a real branch, or this may happen in the
+        // future. If this is going to happen in the future, then the actual
+        // bits that are written here don't matter (except the condition code,
+        // since that is always preserved across patchings) but if it does not
+        // get bound later, then we want to make sure this is a load from the
+        // pool entry (and the pool entry should be nullptr so it will crash).
+        if (data.isValidPoolHint()) {
+            Assembler::as_dtr_patch(IsLoad, 32, Offset, pc,
+                                    DTRAddr(pc, DtrOffImm(offset+4*data.getIndex() - 8)),
+                                    data.getCond(), instAddr);
+        }
+        break;
+      case PoolHintData::PoolVDTR: {
+        VFPRegister dest = data.getVFPReg();
+        int32_t imm = offset + (data.getIndex() * 4) - 8;
+        MOZ_ASSERT(-1024 < imm && imm < 1024);
+        Assembler::as_vdtr_patch(IsLoad, dest, VFPAddr(pc, VFPOffImm(imm)), data.getCond(),
+                                 instAddr);
+        break;
+      }
+    }
+}
+
+// Atomic instruction stuff:
+
+BufferOffset
+Assembler::as_ldrex(Register rt, Register rn, Condition c)
+{
+    return writeInst(0x01900f9f | (int)c | RT(rt) | RN(rn));
+}
+
+BufferOffset
+Assembler::as_ldrexh(Register rt, Register rn, Condition c)
+{
+    return writeInst(0x01f00f9f | (int)c | RT(rt) | RN(rn));
+}
+
+BufferOffset
+Assembler::as_ldrexb(Register rt, Register rn, Condition c)
+{
+    return writeInst(0x01d00f9f | (int)c | RT(rt) | RN(rn));
+}
+
+BufferOffset
+Assembler::as_strex(Register rd, Register rt, Register rn, Condition c)
+{
+    MOZ_ASSERT(rd != rn && rd != rt); // True restriction on Cortex-A7 (RPi2)
+    return writeInst(0x01800f90 | (int)c | RD(rd) | RN(rn) | rt.code());
+}
+
+BufferOffset
+Assembler::as_strexh(Register rd, Register rt, Register rn, Condition c)
+{
+    MOZ_ASSERT(rd != rn && rd != rt); // True restriction on Cortex-A7 (RPi2)
+    return writeInst(0x01e00f90 | (int)c | RD(rd) | RN(rn) | rt.code());
+}
+
+BufferOffset
+Assembler::as_strexb(Register rd, Register rt, Register rn, Condition c)
+{
+    MOZ_ASSERT(rd != rn && rd != rt); // True restriction on Cortex-A7 (RPi2)
+    return writeInst(0x01c00f90 | (int)c | RD(rd) | RN(rn) | rt.code());
+}
+
+// Memory barrier stuff:
+
+BufferOffset
+Assembler::as_dmb(BarrierOption option)
+{
+    return writeInst(0xf57ff050U | (int)option);
+}
+BufferOffset
+Assembler::as_dsb(BarrierOption option)
+{
+    return writeInst(0xf57ff040U | (int)option);
+}
+BufferOffset
+Assembler::as_isb()
+{
+    return writeInst(0xf57ff06fU); // option == SY
+}
+BufferOffset
+Assembler::as_dsb_trap()
+{
+    // DSB is "mcr 15, 0, r0, c7, c10, 4".
+    // See eg https://bugs.kde.org/show_bug.cgi?id=228060.
+    // ARMv7 manual, "VMSA CP15 c7 register summary".
+    // Flagged as "legacy" starting with ARMv8, may be disabled on chip, see
+    // ARMv8 manual E2.7.3 and G3.18.16.
+    return writeInst(0xee070f9a);
+}
+BufferOffset
+Assembler::as_dmb_trap()
+{
+    // DMB is "mcr 15, 0, r0, c7, c10, 5".
+    // ARMv7 manual, "VMSA CP15 c7 register summary".
+    // Flagged as "legacy" starting with ARMv8, may be disabled on chip, see
+    // ARMv8 manual E2.7.3 and G3.18.16.
+    return writeInst(0xee070fba);
+}
+BufferOffset
+Assembler::as_isb_trap()
+{
+    // ISB is "mcr 15, 0, r0, c7, c5, 4".
+    // ARMv7 manual, "VMSA CP15 c7 register summary".
+    // Flagged as "legacy" starting with ARMv8, may be disabled on chip, see
+    // ARMv8 manual E2.7.3 and G3.18.16.
+    return writeInst(0xee070f94);
+}
+
+// Control flow stuff:
+
+// bx can *only* branch to a register, never to an immediate.
+BufferOffset
+Assembler::as_bx(Register r, Condition c)
+{
+    BufferOffset ret = writeInst(((int) c) | OpBx | r.code());
+    return ret;
+}
+
+void
+Assembler::WritePoolGuard(BufferOffset branch, Instruction* dest, BufferOffset afterPool)
+{
+    BOffImm off = afterPool.diffB<BOffImm>(branch);
+    if (off.isInvalid())
+        MOZ_CRASH("BOffImm invalid");
+    *dest = InstBImm(off, Always);
+}
+
+// Branch can branch to an immediate *or* to a register.
+// Branches to immediates are pc relative, branches to registers are absolute.
+BufferOffset
+Assembler::as_b(BOffImm off, Condition c, Label* documentation)
+{
+    BufferOffset ret = writeBranchInst(((int)c) | OpB | off.encode(), documentation);
+    return ret;
+}
+
+BufferOffset
+Assembler::as_b(Label* l, Condition c)
+{
+    if (l->bound()) {
+        // Note only one instruction is emitted here, the NOP is overwritten.
+        BufferOffset ret = allocBranchInst();
+        if (oom())
+            return BufferOffset();
+
+        as_b(BufferOffset(l).diffB<BOffImm>(ret), c, ret);
+#ifdef JS_DISASM_ARM
+        spewBranch(m_buffer.getInstOrNull(ret), l);
+#endif
+        return ret;
+    }
+
+    if (oom())
+        return BufferOffset();
+
+    int32_t old;
+    BufferOffset ret;
+    if (l->used()) {
+        old = l->offset();
+        // This will currently throw an assertion if we couldn't actually
+        // encode the offset of the branch.
+        if (!BOffImm::IsInRange(old)) {
+            m_buffer.fail_bail();
+            return ret;
+        }
+        ret = as_b(BOffImm(old), c, l);
+    } else {
+        old = LabelBase::INVALID_OFFSET;
+        BOffImm inv;
+        ret = as_b(inv, c, l);
+    }
+
+    if (oom())
+        return BufferOffset();
+
+    DebugOnly<int32_t> check = l->use(ret.getOffset());
+    MOZ_ASSERT(check == old);
+    return ret;
+}
+
+BufferOffset
+Assembler::as_b(wasm::TrapDesc target, Condition c)
+{
+    Label l;
+    BufferOffset ret = as_b(&l, c);
+    bindLater(&l, target);
+    return ret;
+}
+
+BufferOffset
+Assembler::as_b(BOffImm off, Condition c, BufferOffset inst)
+{
+    // JS_DISASM_ARM NOTE: Can't disassemble here, because numerous callers use this to
+    // patchup old code.  Must disassemble in caller where it makes sense.  Not many callers.
+    *editSrc(inst) = InstBImm(off, c);
+    return inst;
+}
+
+// blx can go to either an immediate or a register.
+// When blx'ing to a register, we change processor state depending on the low
+// bit of the register when blx'ing to an immediate, we *always* change
+// processor state.
+
+BufferOffset
+Assembler::as_blx(Register r, Condition c)
+{
+    return writeInst(((int) c) | OpBlx | r.code());
+}
+
+// bl can only branch to an pc-relative immediate offset
+// It cannot change the processor state.
+BufferOffset
+Assembler::as_bl(BOffImm off, Condition c, Label* documentation)
+{
+    return writeBranchInst(((int)c) | OpBl | off.encode(), documentation);
+}
+
+BufferOffset
+Assembler::as_bl(Label* l, Condition c)
+{
+    if (l->bound()) {
+        // Note only one instruction is emitted here, the NOP is overwritten.
+        BufferOffset ret = allocBranchInst();
+        if (oom())
+            return BufferOffset();
+
+        BOffImm offset = BufferOffset(l).diffB<BOffImm>(ret);
+        if (offset.isInvalid()) {
+            m_buffer.fail_bail();
+            return BufferOffset();
+        }
+
+        as_bl(offset, c, ret);
+#ifdef JS_DISASM_ARM
+        spewBranch(m_buffer.getInstOrNull(ret), l);
+#endif
+        return ret;
+    }
+
+    if (oom())
+        return BufferOffset();
+
+    int32_t old;
+    BufferOffset ret;
+    // See if the list was empty :(
+    if (l->used()) {
+        // This will currently throw an assertion if we couldn't actually encode
+        // the offset of the branch.
+        old = l->offset();
+        if (!BOffImm::IsInRange(old)) {
+            m_buffer.fail_bail();
+            return ret;
+        }
+        ret = as_bl(BOffImm(old), c, l);
+    } else {
+        old = LabelBase::INVALID_OFFSET;
+        BOffImm inv;
+        ret = as_bl(inv, c, l);
+    }
+
+    if (oom())
+        return BufferOffset();
+
+    DebugOnly<int32_t> check = l->use(ret.getOffset());
+    MOZ_ASSERT(check == old);
+    return ret;
+}
+
+BufferOffset
+Assembler::as_bl(BOffImm off, Condition c, BufferOffset inst)
+{
+    *editSrc(inst) = InstBLImm(off, c);
+    return inst;
+}
+
+BufferOffset
+Assembler::as_mrs(Register r, Condition c)
+{
+    return writeInst(0x010f0000 | int(c) | RD(r));
+}
+
+BufferOffset
+Assembler::as_msr(Register r, Condition c)
+{
+    // Hardcode the 'mask' field to 0b11 for now. It is bits 18 and 19, which
+    // are the two high bits of the 'c' in this constant.
+    MOZ_ASSERT((r.code() & ~0xf) == 0);
+    return writeInst(0x012cf000 | int(c) | r.code());
+}
+
+// VFP instructions!
+enum vfp_tags {
+    VfpTag   = 0x0C000A00,
+    VfpArith = 0x02000000
+};
+
+BufferOffset
+Assembler::writeVFPInst(vfp_size sz, uint32_t blob)
+{
+    MOZ_ASSERT((sz & blob) == 0);
+    MOZ_ASSERT((VfpTag & blob) == 0);
+    return writeInst(VfpTag | sz | blob);
+}
+
+/* static */ void
+Assembler::WriteVFPInstStatic(vfp_size sz, uint32_t blob, uint32_t* dest)
+{
+    MOZ_ASSERT((sz & blob) == 0);
+    MOZ_ASSERT((VfpTag & blob) == 0);
+    WriteInstStatic(VfpTag | sz | blob, dest);
+}
+
+// Unityped variants: all registers hold the same (ieee754 single/double)
+// notably not included are vcvt; vmov vd, #imm; vmov rt, vn.
+BufferOffset
+Assembler::as_vfp_float(VFPRegister vd, VFPRegister vn, VFPRegister vm,
+                  VFPOp op, Condition c)
+{
+    // Make sure we believe that all of our operands are the same kind.
+    MOZ_ASSERT_IF(!vn.isMissing(), vd.equiv(vn));
+    MOZ_ASSERT_IF(!vm.isMissing(), vd.equiv(vm));
+    vfp_size sz = vd.isDouble() ? IsDouble : IsSingle;
+    return writeVFPInst(sz, VD(vd) | VN(vn) | VM(vm) | op | VfpArith | c);
+}
+
+BufferOffset
+Assembler::as_vadd(VFPRegister vd, VFPRegister vn, VFPRegister vm, Condition c)
+{
+    return as_vfp_float(vd, vn, vm, OpvAdd, c);
+}
+
+BufferOffset
+Assembler::as_vdiv(VFPRegister vd, VFPRegister vn, VFPRegister vm, Condition c)
+{
+    return as_vfp_float(vd, vn, vm, OpvDiv, c);
+}
+
+BufferOffset
+Assembler::as_vmul(VFPRegister vd, VFPRegister vn, VFPRegister vm, Condition c)
+{
+    return as_vfp_float(vd, vn, vm, OpvMul, c);
+}
+
+BufferOffset
+Assembler::as_vnmul(VFPRegister vd, VFPRegister vn, VFPRegister vm, Condition c)
+{
+    return as_vfp_float(vd, vn, vm, OpvMul, c);
+}
+
+BufferOffset
+Assembler::as_vnmla(VFPRegister vd, VFPRegister vn, VFPRegister vm, Condition c)
+{
+    MOZ_CRASH("Feature NYI");
+}
+
+BufferOffset
+Assembler::as_vnmls(VFPRegister vd, VFPRegister vn, VFPRegister vm, Condition c)
+{
+    MOZ_CRASH("Feature NYI");
+}
+
+BufferOffset
+Assembler::as_vneg(VFPRegister vd, VFPRegister vm, Condition c)
+{
+    return as_vfp_float(vd, NoVFPRegister, vm, OpvNeg, c);
+}
+
+BufferOffset
+Assembler::as_vsqrt(VFPRegister vd, VFPRegister vm, Condition c)
+{
+    return as_vfp_float(vd, NoVFPRegister, vm, OpvSqrt, c);
+}
+
+BufferOffset
+Assembler::as_vabs(VFPRegister vd, VFPRegister vm, Condition c)
+{
+    return as_vfp_float(vd, NoVFPRegister, vm, OpvAbs, c);
+}
+
+BufferOffset
+Assembler::as_vsub(VFPRegister vd, VFPRegister vn, VFPRegister vm, Condition c)
+{
+    return as_vfp_float(vd, vn, vm, OpvSub, c);
+}
+
+BufferOffset
+Assembler::as_vcmp(VFPRegister vd, VFPRegister vm, Condition c)
+{
+    return as_vfp_float(vd, NoVFPRegister, vm, OpvCmp, c);
+}
+
+BufferOffset
+Assembler::as_vcmpz(VFPRegister vd, Condition c)
+{
+    return as_vfp_float(vd, NoVFPRegister, NoVFPRegister, OpvCmpz, c);
+}
+
+// Specifically, a move between two same sized-registers.
+BufferOffset
+Assembler::as_vmov(VFPRegister vd, VFPRegister vsrc, Condition c)
+{
+    return as_vfp_float(vd, NoVFPRegister, vsrc, OpvMov, c);
+}
+
+// Transfer between Core and VFP.
+
+// Unlike the next function, moving between the core registers and vfp registers
+// can't be *that* properly typed. Namely, since I don't want to munge the type
+// VFPRegister to also include core registers. Thus, the core and vfp registers
+// are passed in based on their type, and src/dest is determined by the
+// float2core.
+
+BufferOffset
+Assembler::as_vxfer(Register vt1, Register vt2, VFPRegister vm, FloatToCore_ f2c,
+                    Condition c, int idx)
+{
+    vfp_size sz = IsSingle;
+    if (vm.isDouble()) {
+        // Technically, this can be done with a vmov à la ARM ARM under vmov
+        // however, that requires at least an extra bit saying if the operation
+        // should be performed on the lower or upper half of the double. Moving
+        // a single to/from 2N/2N+1 isn't equivalent, since there are 32 single
+        // registers, and 32 double registers so there is no way to encode the
+        // last 16 double registers.
+        sz = IsDouble;
+        MOZ_ASSERT(idx == 0 || idx == 1);
+        // If we are transferring a single half of the double then it must be
+        // moving a VFP reg to a core reg.
+        MOZ_ASSERT_IF(vt2 == InvalidReg, f2c == FloatToCore);
+        idx = idx << 21;
+    } else {
+        MOZ_ASSERT(idx == 0);
+    }
+
+    if (vt2 == InvalidReg)
+        return writeVFPInst(sz, WordTransfer | f2c | c | RT(vt1) | maybeRN(vt2) | VN(vm) | idx);
+
+    // We are doing a 64 bit transfer.
+    return writeVFPInst(sz, DoubleTransfer | f2c | c | RT(vt1) | maybeRN(vt2) | VM(vm) | idx);
+}
+
+enum vcvt_destFloatness {
+    VcvtToInteger = 1 << 18,
+    VcvtToFloat  = 0 << 18
+};
+enum vcvt_toZero {
+    VcvtToZero = 1 << 7, // Use the default rounding mode, which rounds truncates.
+    VcvtToFPSCR = 0 << 7 // Use whatever rounding mode the fpscr specifies.
+};
+enum vcvt_Signedness {
+    VcvtToSigned   = 1 << 16,
+    VcvtToUnsigned = 0 << 16,
+    VcvtFromSigned   = 1 << 7,
+    VcvtFromUnsigned = 0 << 7
+};
+
+// Our encoding actually allows just the src and the dest (and their types) to
+// uniquely specify the encoding that we are going to use.
+BufferOffset
+Assembler::as_vcvt(VFPRegister vd, VFPRegister vm, bool useFPSCR,
+                   Condition c)
+{
+    // Unlike other cases, the source and dest types cannot be the same.
+    MOZ_ASSERT(!vd.equiv(vm));
+    vfp_size sz = IsDouble;
+    if (vd.isFloat() && vm.isFloat()) {
+        // Doing a float -> float conversion.
+        if (vm.isSingle())
+            sz = IsSingle;
+        return writeVFPInst(sz, c | 0x02B700C0 | VM(vm) | VD(vd));
+    }
+
+    // At least one of the registers should be a float.
+    vcvt_destFloatness destFloat;
+    vcvt_Signedness opSign;
+    vcvt_toZero doToZero = VcvtToFPSCR;
+    MOZ_ASSERT(vd.isFloat() || vm.isFloat());
+    if (vd.isSingle() || vm.isSingle())
+        sz = IsSingle;
+
+    if (vd.isFloat()) {
+        destFloat = VcvtToFloat;
+        opSign = (vm.isSInt()) ? VcvtFromSigned : VcvtFromUnsigned;
+    } else {
+        destFloat = VcvtToInteger;
+        opSign = (vd.isSInt()) ? VcvtToSigned : VcvtToUnsigned;
+        doToZero = useFPSCR ? VcvtToFPSCR : VcvtToZero;
+    }
+    return writeVFPInst(sz, c | 0x02B80040 | VD(vd) | VM(vm) | destFloat | opSign | doToZero);
+}
+
+BufferOffset
+Assembler::as_vcvtFixed(VFPRegister vd, bool isSigned, uint32_t fixedPoint, bool toFixed, Condition c)
+{
+    MOZ_ASSERT(vd.isFloat());
+    uint32_t sx = 0x1;
+    vfp_size sf = vd.isDouble() ? IsDouble : IsSingle;
+    int32_t imm5 = fixedPoint;
+    imm5 = (sx ? 32 : 16) - imm5;
+    MOZ_ASSERT(imm5 >= 0);
+    imm5 = imm5 >> 1 | (imm5 & 1) << 5;
+    return writeVFPInst(sf, 0x02BA0040 | VD(vd) | toFixed << 18 | sx << 7 |
+                        (!isSigned) << 16 | imm5 | c);
+}
+
+// Transfer between VFP and memory.
+static uint32_t
+EncodeVdtr(LoadStore ls, VFPRegister vd, VFPAddr addr, Assembler::Condition c)
+{
+    return ls | 0x01000000 | addr.encode() | VD(vd) | c;
+}
+
+BufferOffset
+Assembler::as_vdtr(LoadStore ls, VFPRegister vd, VFPAddr addr,
+                   Condition c /* vfp doesn't have a wb option */)
+{
+    vfp_size sz = vd.isDouble() ? IsDouble : IsSingle;
+    return writeVFPInst(sz, EncodeVdtr(ls, vd, addr, c));
+}
+
+/* static */ void
+Assembler::as_vdtr_patch(LoadStore ls, VFPRegister vd, VFPAddr addr, Condition c, uint32_t* dest)
+{
+    vfp_size sz = vd.isDouble() ? IsDouble : IsSingle;
+    WriteVFPInstStatic(sz, EncodeVdtr(ls, vd, addr, c), dest);
+}
+
+// VFP's ldm/stm work differently from the standard arm ones. You can only
+// transfer a range.
+
+BufferOffset
+Assembler::as_vdtm(LoadStore st, Register rn, VFPRegister vd, int length,
+                   /* also has update conditions */ Condition c)
+{
+    MOZ_ASSERT(length <= 16 && length >= 0);
+    vfp_size sz = vd.isDouble() ? IsDouble : IsSingle;
+
+    if (vd.isDouble())
+        length *= 2;
+
+    return writeVFPInst(sz, dtmLoadStore | RN(rn) | VD(vd) | length |
+                        dtmMode | dtmUpdate | dtmCond);
+}
+
+BufferOffset
+Assembler::as_vimm(VFPRegister vd, VFPImm imm, Condition c)
+{
+    MOZ_ASSERT(imm.isValid());
+    vfp_size sz = vd.isDouble() ? IsDouble : IsSingle;
+    return writeVFPInst(sz,  c | imm.encode() | VD(vd) | 0x02B00000);
+
+}
+
+BufferOffset
+Assembler::as_vmrs(Register r, Condition c)
+{
+    return writeInst(c | 0x0ef10a10 | RT(r));
+}
+
+BufferOffset
+Assembler::as_vmsr(Register r, Condition c)
+{
+    return writeInst(c | 0x0ee10a10 | RT(r));
+}
+
+bool
+Assembler::nextLink(BufferOffset b, BufferOffset* next)
+{
+    Instruction branch = *editSrc(b);
+    MOZ_ASSERT(branch.is<InstBranchImm>());
+
+    BOffImm destOff;
+    branch.as<InstBranchImm>()->extractImm(&destOff);
+    if (destOff.isInvalid())
+        return false;
+
+    // Propagate the next link back to the caller, by constructing a new
+    // BufferOffset into the space they provided.
+    new (next) BufferOffset(destOff.decode());
+    return true;
+}
+
+void
+Assembler::bind(Label* label, BufferOffset boff)
+{
+#ifdef JS_DISASM_ARM
+    spewLabel(label);
+#endif
+    if (oom()) {
+        // Ensure we always bind the label. This matches what we do on
+        // x86/x64 and silences the assert in ~Label.
+        label->bind(0);
+        return;
+    }
+
+    if (label->used()) {
+        bool more;
+        // If our caller didn't give us an explicit target to bind to then we
+        // want to bind to the location of the next instruction.
+        BufferOffset dest = boff.assigned() ? boff : nextOffset();
+        BufferOffset b(label);
+        do {
+            BufferOffset next;
+            more = nextLink(b, &next);
+            Instruction branch = *editSrc(b);
+            Condition c = branch.extractCond();
+            BOffImm offset = dest.diffB<BOffImm>(b);
+            if (offset.isInvalid()) {
+                m_buffer.fail_bail();
+                return;
+            }
+            if (branch.is<InstBImm>())
+                as_b(offset, c, b);
+            else if (branch.is<InstBLImm>())
+                as_bl(offset, c, b);
+            else
+                MOZ_CRASH("crazy fixup!");
+            b = next;
+        } while (more);
+    }
+    label->bind(nextOffset().getOffset());
+    MOZ_ASSERT(!oom());
+}
+
+void
+Assembler::bindLater(Label* label, wasm::TrapDesc target)
+{
+    if (label->used()) {
+        BufferOffset b(label);
+        do {
+            append(wasm::TrapSite(target, b.getOffset()));
+        } while (nextLink(b, &b));
+    }
+    label->reset();
+}
+
+void
+Assembler::bind(RepatchLabel* label)
+{
+    // It does not seem to be useful to record this label for
+    // disassembly, as the value that is bound to the label is often
+    // effectively garbage and is replaced by something else later.
+    BufferOffset dest = nextOffset();
+    if (label->used() && !oom()) {
+        // If the label has a use, then change this use to refer to the bound
+        // label.
+        BufferOffset branchOff(label->offset());
+        // Since this was created with a RepatchLabel, the value written in the
+        // instruction stream is not branch shaped, it is PoolHintData shaped.
+        Instruction* branch = editSrc(branchOff);
+        PoolHintPun p;
+        p.raw = branch->encode();
+        Condition cond;
+        if (p.phd.isValidPoolHint())
+            cond = p.phd.getCond();
+        else
+            cond = branch->extractCond();
+
+        BOffImm offset = dest.diffB<BOffImm>(branchOff);
+        if (offset.isInvalid()) {
+            m_buffer.fail_bail();
+            return;
+        }
+        as_b(offset, cond, branchOff);
+    }
+    label->bind(dest.getOffset());
+}
+
+void
+Assembler::retarget(Label* label, Label* target)
+{
+#ifdef JS_DISASM_ARM
+    spewRetarget(label, target);
+#endif
+    if (label->used() && !oom()) {
+        if (target->bound()) {
+            bind(label, BufferOffset(target));
+        } else if (target->used()) {
+            // The target is not bound but used. Prepend label's branch list
+            // onto target's.
+            BufferOffset labelBranchOffset(label);
+            BufferOffset next;
+
+            // Find the head of the use chain for label.
+            while (nextLink(labelBranchOffset, &next))
+                labelBranchOffset = next;
+
+            // Then patch the head of label's use chain to the tail of target's
+            // use chain, prepending the entire use chain of target.
+            Instruction branch = *editSrc(labelBranchOffset);
+            Condition c = branch.extractCond();
+            int32_t prev = target->use(label->offset());
+            if (branch.is<InstBImm>())
+                as_b(BOffImm(prev), c, labelBranchOffset);
+            else if (branch.is<InstBLImm>())
+                as_bl(BOffImm(prev), c, labelBranchOffset);
+            else
+                MOZ_CRASH("crazy fixup!");
+        } else {
+            // The target is unbound and unused. We can just take the head of
+            // the list hanging off of label, and dump that into target.
+            DebugOnly<uint32_t> prev = target->use(label->offset());
+            MOZ_ASSERT((int32_t)prev == Label::INVALID_OFFSET);
+        }
+    }
+    label->reset();
+
+}
+
+static int stopBKPT = -1;
+void
+Assembler::as_bkpt()
+{
+    // This is a count of how many times a breakpoint instruction has been
+    // generated. It is embedded into the instruction for debugging
+    // purposes. Gdb will print "bkpt xxx" when you attempt to dissassemble a
+    // breakpoint with the number xxx embedded into it. If this breakpoint is
+    // being hit, then you can run (in gdb):
+    //  >b dbg_break
+    //  >b main
+    //  >commands
+    //  >set stopBKPT = xxx
+    //  >c
+    //  >end
+    // which will set a breakpoint on the function dbg_break above set a
+    // scripted breakpoint on main that will set the (otherwise unmodified)
+    // value to the number of the breakpoint, so dbg_break will actuall be
+    // called and finally, when you run the executable, execution will halt when
+    // that breakpoint is generated.
+    static int hit = 0;
+    if (stopBKPT == hit)
+        dbg_break();
+    writeInst(0xe1200070 | (hit & 0xf) | ((hit & 0xfff0) << 4));
+    hit++;
+}
+
+void
+Assembler::flushBuffer()
+{
+    m_buffer.flushPool();
+}
+
+void
+Assembler::enterNoPool(size_t maxInst)
+{
+    m_buffer.enterNoPool(maxInst);
+}
+
+void
+Assembler::leaveNoPool()
+{
+    m_buffer.leaveNoPool();
+}
+
+ptrdiff_t
+Assembler::GetBranchOffset(const Instruction* i_)
+{
+    MOZ_ASSERT(i_->is<InstBranchImm>());
+    InstBranchImm* i = i_->as<InstBranchImm>();
+    BOffImm dest;
+    i->extractImm(&dest);
+    return dest.decode();
+}
+
+void
+Assembler::RetargetNearBranch(Instruction* i, int offset, bool final)
+{
+    Assembler::Condition c = i->extractCond();
+    RetargetNearBranch(i, offset, c, final);
+}
+
+void
+Assembler::RetargetNearBranch(Instruction* i, int offset, Condition cond, bool final)
+{
+    // Retargeting calls is totally unsupported!
+    MOZ_ASSERT_IF(i->is<InstBranchImm>(), i->is<InstBImm>() || i->is<InstBLImm>());
+    if (i->is<InstBLImm>())
+        new (i) InstBLImm(BOffImm(offset), cond);
+    else
+        new (i) InstBImm(BOffImm(offset), cond);
+
+    // Flush the cache, since an instruction was overwritten.
+    if (final)
+        AutoFlushICache::flush(uintptr_t(i), 4);
+}
+
+void
+Assembler::RetargetFarBranch(Instruction* i, uint8_t** slot, uint8_t* dest, Condition cond)
+{
+    int32_t offset = reinterpret_cast<uint8_t*>(slot) - reinterpret_cast<uint8_t*>(i);
+    if (!i->is<InstLDR>()) {
+        new (i) InstLDR(Offset, pc, DTRAddr(pc, DtrOffImm(offset - 8)), cond);
+        AutoFlushICache::flush(uintptr_t(i), 4);
+    }
+    *slot = dest;
+}
+
+struct PoolHeader : Instruction
+{
+    struct Header
+    {
+        // The size should take into account the pool header.
+        // The size is in units of Instruction (4 bytes), not byte.
+        uint32_t size : 15;
+        bool isNatural : 1;
+        uint32_t ONES : 16;
+
+        Header(int size_, bool isNatural_)
+          : size(size_),
+            isNatural(isNatural_),
+            ONES(0xffff)
+        { }
+
+        Header(const Instruction* i) {
+            JS_STATIC_ASSERT(sizeof(Header) == sizeof(uint32_t));
+            memcpy(this, i, sizeof(Header));
+            MOZ_ASSERT(ONES == 0xffff);
+        }
+
+        uint32_t raw() const {
+            JS_STATIC_ASSERT(sizeof(Header) == sizeof(uint32_t));
+            uint32_t dest;
+            memcpy(&dest, this, sizeof(Header));
+            return dest;
+        }
+    };
+
+    PoolHeader(int size_, bool isNatural_)
+      : Instruction(Header(size_, isNatural_).raw(), true)
+    { }
+
+    uint32_t size() const {
+        Header tmp(this);
+        return tmp.size;
+    }
+    uint32_t isNatural() const {
+        Header tmp(this);
+        return tmp.isNatural;
+    }
+
+    static bool IsTHIS(const Instruction& i) {
+        return (*i.raw() & 0xffff0000) == 0xffff0000;
+    }
+    static const PoolHeader* AsTHIS(const Instruction& i) {
+        if (!IsTHIS(i))
+            return nullptr;
+        return static_cast<const PoolHeader*>(&i);
+    }
+};
+
+void
+Assembler::WritePoolHeader(uint8_t* start, Pool* p, bool isNatural)
+{
+    static_assert(sizeof(PoolHeader) == 4, "PoolHandler must have the correct size.");
+    uint8_t* pool = start + 4;
+    // Go through the usual rigmarole to get the size of the pool.
+    pool += p->getPoolSize();
+    uint32_t size = pool - start;
+    MOZ_ASSERT((size & 3) == 0);
+    size = size >> 2;
+    MOZ_ASSERT(size < (1 << 15));
+    PoolHeader header(size, isNatural);
+    *(PoolHeader*)start = header;
+}
+
+// The size of an arbitrary 32-bit call in the instruction stream. On ARM this
+// sequence is |pc = ldr pc - 4; imm32| given that we never reach the imm32.
+uint32_t
+Assembler::PatchWrite_NearCallSize()
+{
+    return sizeof(uint32_t);
+}
+
+void
+Assembler::PatchWrite_NearCall(CodeLocationLabel start, CodeLocationLabel toCall)
+{
+    Instruction* inst = (Instruction*) start.raw();
+    // Overwrite whatever instruction used to be here with a call. Since the
+    // destination is in the same function, it will be within range of the
+    // 24 << 2 byte bl instruction.
+    uint8_t* dest = toCall.raw();
+    new (inst) InstBLImm(BOffImm(dest - (uint8_t*)inst) , Always);
+    // Ensure everyone sees the code that was just written into memory.
+    AutoFlushICache::flush(uintptr_t(inst), 4);
+}
+
+void
+Assembler::PatchDataWithValueCheck(CodeLocationLabel label, PatchedImmPtr newValue,
+                                   PatchedImmPtr expectedValue)
+{
+    Instruction* ptr = reinterpret_cast<Instruction*>(label.raw());
+    InstructionIterator iter(ptr);
+    Register dest;
+    Assembler::RelocStyle rs;
+
+    DebugOnly<const uint32_t*> val = GetPtr32Target(&iter, &dest, &rs);
+    MOZ_ASSERT(uint32_t((const uint32_t*)val) == uint32_t(expectedValue.value));
+
+    MacroAssembler::ma_mov_patch(Imm32(int32_t(newValue.value)), dest, Always, rs, ptr);
+
+    // L_LDR won't cause any instructions to be updated.
+    if (rs != L_LDR) {
+        AutoFlushICache::flush(uintptr_t(ptr), 4);
+        AutoFlushICache::flush(uintptr_t(ptr->next()), 4);
+    }
+}
+
+void
+Assembler::PatchDataWithValueCheck(CodeLocationLabel label, ImmPtr newValue, ImmPtr expectedValue)
+{
+    PatchDataWithValueCheck(label,
+                            PatchedImmPtr(newValue.value),
+                            PatchedImmPtr(expectedValue.value));
+}
+
+// This just stomps over memory with 32 bits of raw data. Its purpose is to
+// overwrite the call of JITed code with 32 bits worth of an offset. This will
+// is only meant to function on code that has been invalidated, so it should be
+// totally safe. Since that instruction will never be executed again, a ICache
+// flush should not be necessary
+void
+Assembler::PatchWrite_Imm32(CodeLocationLabel label, Imm32 imm) {
+    // Raw is going to be the return address.
+    uint32_t* raw = (uint32_t*)label.raw();
+    // Overwrite the 4 bytes before the return address, which will end up being
+    // the call instruction.
+    *(raw - 1) = imm.value;
+}
+
+uint8_t*
+Assembler::NextInstruction(uint8_t* inst_, uint32_t* count)
+{
+    Instruction* inst = reinterpret_cast<Instruction*>(inst_);
+    if (count != nullptr)
+        *count += sizeof(Instruction);
+    return reinterpret_cast<uint8_t*>(inst->next());
+}
+
+static bool
+InstIsGuard(Instruction* inst, const PoolHeader** ph)
+{
+    Assembler::Condition c = inst->extractCond();
+    if (c != Assembler::Always)
+        return false;
+    if (!(inst->is<InstBXReg>() || inst->is<InstBImm>()))
+        return false;
+    // See if the next instruction is a pool header.
+    *ph = (inst + 1)->as<const PoolHeader>();
+    return *ph != nullptr;
+}
+
+static bool
+InstIsBNop(Instruction* inst)
+{
+    // In some special situations, it is necessary to insert a NOP into the
+    // instruction stream that nobody knows about, since nobody should know
+    // about it, make sure it gets skipped when Instruction::next() is called.
+    // this generates a very specific nop, namely a branch to the next
+    // instruction.
+    Assembler::Condition c = inst->extractCond();
+    if (c != Assembler::Always)
+        return false;
+    if (!inst->is<InstBImm>())
+        return false;
+    InstBImm* b = inst->as<InstBImm>();
+    BOffImm offset;
+    b->extractImm(&offset);
+    return offset.decode() == 4;
+}
+
+static bool
+InstIsArtificialGuard(Instruction* inst, const PoolHeader** ph)
+{
+    if (!InstIsGuard(inst, ph))
+        return false;
+    return !(*ph)->isNatural();
+}
+
+// If the instruction points to a artificial pool guard then skip the pool.
+Instruction*
+Instruction::skipPool()
+{
+    const PoolHeader* ph;
+    // If this is a guard, and the next instruction is a header, always work
+    // around the pool. If it isn't a guard, then start looking ahead.
+    if (InstIsGuard(this, &ph)) {
+        // Don't skip a natural guard.
+        if (ph->isNatural())
+            return this;
+        return (this + 1 + ph->size())->skipPool();
+    }
+    if (InstIsBNop(this))
+        return (this + 1)->skipPool();
+    return this;
+}
+
+// Cases to be handled:
+// 1) no pools or branches in sight => return this+1
+// 2) branch to next instruction => return this+2, because a nop needed to be inserted into the stream.
+// 3) this+1 is an artificial guard for a pool => return first instruction after the pool
+// 4) this+1 is a natural guard => return the branch
+// 5) this is a branch, right before a pool => return first instruction after the pool
+// in assembly form:
+// 1) add r0, r0, r0 <= this
+//    add r1, r1, r1 <= returned value
+//    add r2, r2, r2
+//
+// 2) add r0, r0, r0 <= this
+//    b foo
+//    foo:
+//    add r2, r2, r2 <= returned value
+//
+// 3) add r0, r0, r0 <= this
+//    b after_pool;
+//    .word 0xffff0002  # bit 15 being 0 indicates that the branch was not requested by the assembler
+//    0xdeadbeef        # the 2 indicates that there is 1 pool entry, and the pool header
+//    add r4, r4, r4 <= returned value
+// 4) add r0, r0, r0 <= this
+//    b after_pool  <= returned value
+//    .word 0xffff8002  # bit 15 being 1 indicates that the branch was requested by the assembler
+//    0xdeadbeef
+//    add r4, r4, r4
+// 5) b after_pool  <= this
+//    .word 0xffff8002  # bit 15 has no bearing on the returned value
+//    0xdeadbeef
+//    add r4, r4, r4  <= returned value
+
+Instruction*
+Instruction::next()
+{
+    Instruction* ret = this+1;
+    const PoolHeader* ph;
+    // If this is a guard, and the next instruction is a header, always work
+    // around the pool. If it isn't a guard, then start looking ahead.
+    if (InstIsGuard(this, &ph))
+        return (ret + ph->size())->skipPool();
+    if (InstIsArtificialGuard(ret, &ph))
+        return (ret + 1 + ph->size())->skipPool();
+    return ret->skipPool();
+}
+
+void
+Assembler::ToggleToJmp(CodeLocationLabel inst_)
+{
+    uint32_t* ptr = (uint32_t*)inst_.raw();
+
+    DebugOnly<Instruction*> inst = (Instruction*)inst_.raw();
+    MOZ_ASSERT(inst->is<InstCMP>());
+
+    // Zero bits 20-27, then set 24-27 to be correct for a branch.
+    // 20-23 will be party of the B's immediate, and should be 0.
+    *ptr = (*ptr & ~(0xff << 20)) | (0xa0 << 20);
+    AutoFlushICache::flush(uintptr_t(ptr), 4);
+}
+
+void
+Assembler::ToggleToCmp(CodeLocationLabel inst_)
+{
+    uint32_t* ptr = (uint32_t*)inst_.raw();
+
+    DebugOnly<Instruction*> inst = (Instruction*)inst_.raw();
+    MOZ_ASSERT(inst->is<InstBImm>());
+
+    // Ensure that this masking operation doesn't affect the offset of the
+    // branch instruction when it gets toggled back.
+    MOZ_ASSERT((*ptr & (0xf << 20)) == 0);
+
+    // Also make sure that the CMP is valid. Part of having a valid CMP is that
+    // all of the bits describing the destination in most ALU instructions are
+    // all unset (looks like it is encoding r0).
+    MOZ_ASSERT(toRD(*inst) == r0);
+
+    // Zero out bits 20-27, then set them to be correct for a compare.
+    *ptr = (*ptr & ~(0xff << 20)) | (0x35 << 20);
+
+    AutoFlushICache::flush(uintptr_t(ptr), 4);
+}
+
+void
+Assembler::ToggleCall(CodeLocationLabel inst_, bool enabled)
+{
+    Instruction* inst = (Instruction*)inst_.raw();
+    // Skip a pool with an artificial guard.
+    inst = inst->skipPool();
+    MOZ_ASSERT(inst->is<InstMovW>() || inst->is<InstLDR>());
+
+    if (inst->is<InstMovW>()) {
+        // If it looks like the start of a movw/movt sequence, then make sure we
+        // have all of it (and advance the iterator past the full sequence).
+        inst = inst->next();
+        MOZ_ASSERT(inst->is<InstMovT>());
+    }
+
+    inst = inst->next();
+    MOZ_ASSERT(inst->is<InstNOP>() || inst->is<InstBLXReg>());
+
+    if (enabled == inst->is<InstBLXReg>()) {
+        // Nothing to do.
+        return;
+    }
+
+    if (enabled)
+        *inst = InstBLXReg(ScratchRegister, Always);
+    else
+        *inst = InstNOP();
+
+    AutoFlushICache::flush(uintptr_t(inst), 4);
+}
+
+size_t
+Assembler::ToggledCallSize(uint8_t* code)
+{
+    Instruction* inst = (Instruction*)code;
+    // Skip a pool with an artificial guard.
+    inst = inst->skipPool();
+    MOZ_ASSERT(inst->is<InstMovW>() || inst->is<InstLDR>());
+
+    if (inst->is<InstMovW>()) {
+        // If it looks like the start of a movw/movt sequence, then make sure we
+        // have all of it (and advance the iterator past the full sequence).
+        inst = inst->next();
+        MOZ_ASSERT(inst->is<InstMovT>());
+    }
+
+    inst = inst->next();
+    MOZ_ASSERT(inst->is<InstNOP>() || inst->is<InstBLXReg>());
+    return uintptr_t(inst) + 4 - uintptr_t(code);
+}
+
+uint8_t*
+Assembler::BailoutTableStart(uint8_t* code)
+{
+    Instruction* inst = (Instruction*)code;
+    // Skip a pool with an artificial guard or NOP fill.
+    inst = inst->skipPool();
+    MOZ_ASSERT(inst->is<InstBLImm>());
+    return (uint8_t*) inst;
+}
+
+InstructionIterator::InstructionIterator(Instruction* i_)
+  : i(i_)
+{
+    // Work around pools with an artificial pool guard and around nop-fill.
+    i = i->skipPool();
+}
+
+uint32_t Assembler::NopFill = 0;
+
+uint32_t
+Assembler::GetNopFill()
+{
+    static bool isSet = false;
+    if (!isSet) {
+        char* fillStr = getenv("ARM_ASM_NOP_FILL");
+        uint32_t fill;
+        if (fillStr && sscanf(fillStr, "%u", &fill) == 1)
+            NopFill = fill;
+        if (NopFill > 8)
+            MOZ_CRASH("Nop fill > 8 is not supported");
+        isSet = true;
+    }
+    return NopFill;
+}
+
+uint32_t Assembler::AsmPoolMaxOffset = 1024;
+
+uint32_t
+Assembler::GetPoolMaxOffset()
+{
+    static bool isSet = false;
+    if (!isSet) {
+        char* poolMaxOffsetStr = getenv("ASM_POOL_MAX_OFFSET");
+        uint32_t poolMaxOffset;
+        if (poolMaxOffsetStr && sscanf(poolMaxOffsetStr, "%u", &poolMaxOffset) == 1)
+            AsmPoolMaxOffset = poolMaxOffset;
+        isSet = true;
+    }
+    return AsmPoolMaxOffset;
+}
+
+SecondScratchRegisterScope::SecondScratchRegisterScope(MacroAssembler &masm)
+  : AutoRegisterScope(masm, masm.getSecondScratchReg())
+{
+}
diff --git a/js/src/jit/arm/Assembler-arm.h b/js/src/jit/arm/Assembler-arm.h
new file mode 100644
index 0000000000..8bb754a50d
--- /dev/null
+++ b/js/src/jit/arm/Assembler-arm.h
@@ -0,0 +1,2429 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef jit_arm_Assembler_arm_h
+#define jit_arm_Assembler_arm_h
+
+#include "mozilla/ArrayUtils.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/MathAlgorithms.h"
+
+#include "jit/arm/Architecture-arm.h"
+#include "jit/CompactBuffer.h"
+#include "jit/IonCode.h"
+#include "jit/JitCompartment.h"
+#include "jit/shared/Assembler-shared.h"
+#include "jit/shared/IonAssemblerBufferWithConstantPools.h"
+
+namespace js {
+namespace jit {
+
+// NOTE: there are duplicates in this list! Sometimes we want to specifically
+// refer to the link register as a link register (bl lr is much clearer than bl
+// r14). HOWEVER, this register can easily be a gpr when it is not busy holding
+// the return address.
+static constexpr Register r0  = { Registers::r0 };
+static constexpr Register r1  = { Registers::r1 };
+static constexpr Register r2  = { Registers::r2 };
+static constexpr Register r3  = { Registers::r3 };
+static constexpr Register r4  = { Registers::r4 };
+static constexpr Register r5  = { Registers::r5 };
+static constexpr Register r6  = { Registers::r6 };
+static constexpr Register r7  = { Registers::r7 };
+static constexpr Register r8  = { Registers::r8 };
+static constexpr Register r9  = { Registers::r9 };
+static constexpr Register r10 = { Registers::r10 };
+static constexpr Register r11 = { Registers::r11 };
+static constexpr Register r12 = { Registers::ip };
+static constexpr Register ip  = { Registers::ip };
+static constexpr Register sp  = { Registers::sp };
+static constexpr Register r14 = { Registers::lr };
+static constexpr Register lr  = { Registers::lr };
+static constexpr Register pc  = { Registers::pc };
+
+static constexpr Register ScratchRegister = {Registers::ip};
+
+// Helper class for ScratchRegister usage. Asserts that only one piece
+// of code thinks it has exclusive ownership of the scratch register.
+struct ScratchRegisterScope : public AutoRegisterScope
+{
+    explicit ScratchRegisterScope(MacroAssembler& masm)
+      : AutoRegisterScope(masm, ScratchRegister)
+    { }
+};
+
+struct SecondScratchRegisterScope : public AutoRegisterScope
+{
+    explicit SecondScratchRegisterScope(MacroAssembler& masm);
+};
+
+static constexpr Register OsrFrameReg = r3;
+static constexpr Register ArgumentsRectifierReg = r8;
+static constexpr Register CallTempReg0 = r5;
+static constexpr Register CallTempReg1 = r6;
+static constexpr Register CallTempReg2 = r7;
+static constexpr Register CallTempReg3 = r8;
+static constexpr Register CallTempReg4 = r0;
+static constexpr Register CallTempReg5 = r1;
+
+static constexpr Register IntArgReg0 = r0;
+static constexpr Register IntArgReg1 = r1;
+static constexpr Register IntArgReg2 = r2;
+static constexpr Register IntArgReg3 = r3;
+static constexpr Register GlobalReg = r10;
+static constexpr Register HeapReg = r11;
+static constexpr Register CallTempNonArgRegs[] = { r5, r6, r7, r8 };
+static const uint32_t NumCallTempNonArgRegs =
+    mozilla::ArrayLength(CallTempNonArgRegs);
+
+class ABIArgGenerator
+{
+    unsigned intRegIndex_;
+    unsigned floatRegIndex_;
+    uint32_t stackOffset_;
+    ABIArg current_;
+
+    // ARM can either use HardFp (use float registers for float arguments), or
+    // SoftFp (use general registers for float arguments) ABI.  We keep this
+    // switch as a runtime switch because wasm always use the HardFp back-end
+    // while the calls to native functions have to use the one provided by the
+    // system.
+    bool useHardFp_;
+
+    ABIArg softNext(MIRType argType);
+    ABIArg hardNext(MIRType argType);
+
+  public:
+    ABIArgGenerator();
+
+    void setUseHardFp(bool useHardFp) {
+        MOZ_ASSERT(intRegIndex_ == 0 && floatRegIndex_ == 0);
+        useHardFp_ = useHardFp;
+    }
+    ABIArg next(MIRType argType);
+    ABIArg& current() { return current_; }
+    uint32_t stackBytesConsumedSoFar() const { return stackOffset_; }
+};
+
+static constexpr Register ABINonArgReg0 = r4;
+static constexpr Register ABINonArgReg1 = r5;
+static constexpr Register ABINonArgReg2 = r6;
+static constexpr Register ABINonArgReturnReg0 = r4;
+static constexpr Register ABINonArgReturnReg1 = r5;
+
+// TLS pointer argument register for WebAssembly functions. This must not alias
+// any other register used for passing function arguments or return values.
+// Preserved by WebAssembly functions.
+static constexpr Register WasmTlsReg = r9;
+
+// Registers used for wasm table calls. These registers must be disjoint
+// from the ABI argument registers, WasmTlsReg and each other.
+static constexpr Register WasmTableCallScratchReg = ABINonArgReg0;
+static constexpr Register WasmTableCallSigReg = ABINonArgReg1;
+static constexpr Register WasmTableCallIndexReg = ABINonArgReg2;
+
+static constexpr Register PreBarrierReg = r1;
+
+static constexpr Register InvalidReg = { Registers::invalid_reg };
+static constexpr FloatRegister InvalidFloatReg;
+
+static constexpr Register JSReturnReg_Type = r3;
+static constexpr Register JSReturnReg_Data = r2;
+static constexpr Register StackPointer = sp;
+static constexpr Register FramePointer = InvalidReg;
+static constexpr Register ReturnReg = r0;
+static constexpr Register64 ReturnReg64(r1, r0);
+static constexpr FloatRegister ReturnFloat32Reg = { FloatRegisters::d0, VFPRegister::Single };
+static constexpr FloatRegister ReturnDoubleReg = { FloatRegisters::d0, VFPRegister::Double};
+static constexpr FloatRegister ReturnSimd128Reg = InvalidFloatReg;
+static constexpr FloatRegister ScratchFloat32Reg = { FloatRegisters::d30, VFPRegister::Single };
+static constexpr FloatRegister ScratchDoubleReg = { FloatRegisters::d15, VFPRegister::Double };
+static constexpr FloatRegister ScratchSimd128Reg = InvalidFloatReg;
+static constexpr FloatRegister ScratchUIntReg = { FloatRegisters::d15, VFPRegister::UInt };
+static constexpr FloatRegister ScratchIntReg = { FloatRegisters::d15, VFPRegister::Int };
+
+struct ScratchFloat32Scope : public AutoFloatRegisterScope
+{
+    explicit ScratchFloat32Scope(MacroAssembler& masm)
+      : AutoFloatRegisterScope(masm, ScratchFloat32Reg)
+    { }
+};
+struct ScratchDoubleScope : public AutoFloatRegisterScope
+{
+    explicit ScratchDoubleScope(MacroAssembler& masm)
+      : AutoFloatRegisterScope(masm, ScratchDoubleReg)
+    { }
+};
+
+// A bias applied to the GlobalReg to allow the use of instructions with small
+// negative immediate offsets which doubles the range of global data that can be
+// accessed with a single instruction.
+static const int32_t WasmGlobalRegBias = 1024;
+
+// Registers used in the GenerateFFIIonExit Enable Activation block.
+static constexpr Register WasmIonExitRegCallee = r4;
+static constexpr Register WasmIonExitRegE0 = r0;
+static constexpr Register WasmIonExitRegE1 = r1;
+
+// Registers used in the GenerateFFIIonExit Disable Activation block.
+// None of these may be the second scratch register (lr).
+static constexpr Register WasmIonExitRegReturnData = r2;
+static constexpr Register WasmIonExitRegReturnType = r3;
+static constexpr Register WasmIonExitRegD0 = r0;
+static constexpr Register WasmIonExitRegD1 = r1;
+static constexpr Register WasmIonExitRegD2 = r4;
+
+// Registerd used in RegExpMatcher instruction (do not use JSReturnOperand).
+static constexpr Register RegExpMatcherRegExpReg = CallTempReg0;
+static constexpr Register RegExpMatcherStringReg = CallTempReg1;
+static constexpr Register RegExpMatcherLastIndexReg = CallTempReg2;
+
+// Registerd used in RegExpTester instruction (do not use ReturnReg).
+static constexpr Register RegExpTesterRegExpReg = CallTempReg0;
+static constexpr Register RegExpTesterStringReg = CallTempReg1;
+static constexpr Register RegExpTesterLastIndexReg = CallTempReg2;
+
+static constexpr FloatRegister d0  = {FloatRegisters::d0, VFPRegister::Double};
+static constexpr FloatRegister d1  = {FloatRegisters::d1, VFPRegister::Double};
+static constexpr FloatRegister d2  = {FloatRegisters::d2, VFPRegister::Double};
+static constexpr FloatRegister d3  = {FloatRegisters::d3, VFPRegister::Double};
+static constexpr FloatRegister d4  = {FloatRegisters::d4, VFPRegister::Double};
+static constexpr FloatRegister d5  = {FloatRegisters::d5, VFPRegister::Double};
+static constexpr FloatRegister d6  = {FloatRegisters::d6, VFPRegister::Double};
+static constexpr FloatRegister d7  = {FloatRegisters::d7, VFPRegister::Double};
+static constexpr FloatRegister d8  = {FloatRegisters::d8, VFPRegister::Double};
+static constexpr FloatRegister d9  = {FloatRegisters::d9, VFPRegister::Double};
+static constexpr FloatRegister d10 = {FloatRegisters::d10, VFPRegister::Double};
+static constexpr FloatRegister d11 = {FloatRegisters::d11, VFPRegister::Double};
+static constexpr FloatRegister d12 = {FloatRegisters::d12, VFPRegister::Double};
+static constexpr FloatRegister d13 = {FloatRegisters::d13, VFPRegister::Double};
+static constexpr FloatRegister d14 = {FloatRegisters::d14, VFPRegister::Double};
+static constexpr FloatRegister d15 = {FloatRegisters::d15, VFPRegister::Double};
+
+
+// For maximal awesomeness, 8 should be sufficent. ldrd/strd (dual-register
+// load/store) operate in a single cycle when the address they are dealing with
+// is 8 byte aligned. Also, the ARM abi wants the stack to be 8 byte aligned at
+// function boundaries. I'm trying to make sure this is always true.
+static constexpr uint32_t ABIStackAlignment = 8;
+static constexpr uint32_t CodeAlignment = 8;
+static constexpr uint32_t JitStackAlignment = 8;
+
+static constexpr uint32_t JitStackValueAlignment = JitStackAlignment / sizeof(Value);
+static_assert(JitStackAlignment % sizeof(Value) == 0 && JitStackValueAlignment >= 1,
+  "Stack alignment should be a non-zero multiple of sizeof(Value)");
+
+// This boolean indicates whether we support SIMD instructions flavoured for
+// this architecture or not. Rather than a method in the LIRGenerator, it is
+// here such that it is accessible from the entire codebase. Once full support
+// for SIMD is reached on all tier-1 platforms, this constant can be deleted.
+static constexpr bool SupportsSimd = false;
+static constexpr uint32_t SimdMemoryAlignment = 8;
+
+static_assert(CodeAlignment % SimdMemoryAlignment == 0,
+  "Code alignment should be larger than any of the alignments which are used for "
+  "the constant sections of the code buffer.  Thus it should be larger than the "
+  "alignment for SIMD constants.");
+
+static_assert(JitStackAlignment % SimdMemoryAlignment == 0,
+  "Stack alignment should be larger than any of the alignments which are used for "
+  "spilled values.  Thus it should be larger than the alignment for SIMD accesses.");
+
+static const uint32_t WasmStackAlignment = SimdMemoryAlignment;
+
+// Does this architecture support SIMD conversions between Uint32x4 and Float32x4?
+static constexpr bool SupportsUint32x4FloatConversions = false;
+
+// Does this architecture support comparisons of unsigned integer vectors?
+static constexpr bool SupportsUint8x16Compares = false;
+static constexpr bool SupportsUint16x8Compares = false;
+static constexpr bool SupportsUint32x4Compares = false;
+
+static const Scale ScalePointer = TimesFour;
+
+class Instruction;
+class InstBranchImm;
+uint32_t RM(Register r);
+uint32_t RS(Register r);
+uint32_t RD(Register r);
+uint32_t RT(Register r);
+uint32_t RN(Register r);
+
+uint32_t maybeRD(Register r);
+uint32_t maybeRT(Register r);
+uint32_t maybeRN(Register r);
+
+Register toRN(Instruction i);
+Register toRM(Instruction i);
+Register toRD(Instruction i);
+Register toR(Instruction i);
+
+class VFPRegister;
+uint32_t VD(VFPRegister vr);
+uint32_t VN(VFPRegister vr);
+uint32_t VM(VFPRegister vr);
+
+// For being passed into the generic vfp instruction generator when there is an
+// instruction that only takes two registers.
+static constexpr VFPRegister NoVFPRegister(VFPRegister::Double, 0, false, true);
+
+struct ImmTag : public Imm32
+{
+    explicit ImmTag(JSValueTag mask)
+      : Imm32(int32_t(mask))
+    { }
+};
+
+struct ImmType : public ImmTag
+{
+    explicit ImmType(JSValueType type)
+      : ImmTag(JSVAL_TYPE_TO_TAG(type))
+    { }
+};
+
+enum Index {
+    Offset = 0 << 21 | 1<<24,
+    PreIndex = 1 << 21 | 1 << 24,
+    PostIndex = 0 << 21 | 0 << 24
+    // The docs were rather unclear on this. It sounds like
+    // 1 << 21 | 0 << 24 encodes dtrt.
+};
+
+enum IsImmOp2_ {
+    IsImmOp2    = 1 << 25,
+    IsNotImmOp2 = 0 << 25
+};
+enum IsImmDTR_ {
+    IsImmDTR    = 0 << 25,
+    IsNotImmDTR = 1 << 25
+};
+// For the extra memory operations, ldrd, ldrsb, ldrh.
+enum IsImmEDTR_ {
+    IsImmEDTR    = 1 << 22,
+    IsNotImmEDTR = 0 << 22
+};
+
+enum ShiftType {
+    LSL = 0, // << 5
+    LSR = 1, // << 5
+    ASR = 2, // << 5
+    ROR = 3, // << 5
+    RRX = ROR // RRX is encoded as ROR with a 0 offset.
+};
+
+// Modes for STM/LDM. Names are the suffixes applied to the instruction.
+enum DTMMode {
+    A = 0 << 24, // empty / after
+    B = 1 << 24, // full / before
+    D = 0 << 23, // decrement
+    I = 1 << 23, // increment
+    DA = D | A,
+    DB = D | B,
+    IA = I | A,
+    IB = I | B
+};
+
+enum DTMWriteBack {
+    WriteBack   = 1 << 21,
+    NoWriteBack = 0 << 21
+};
+
+// Condition code updating mode.
+enum SBit {
+    SetCC   = 1 << 20,  // Set condition code.
+    LeaveCC = 0 << 20   // Leave condition code unchanged.
+};
+
+enum LoadStore {
+    IsLoad  = 1 << 20,
+    IsStore = 0 << 20
+};
+
+// You almost never want to use this directly. Instead, you wantto pass in a
+// signed constant, and let this bit be implicitly set for you. This is however,
+// necessary if we want a negative index.
+enum IsUp_ {
+    IsUp   = 1 << 23,
+    IsDown = 0 << 23
+};
+enum ALUOp {
+    OpMov = 0xd << 21,
+    OpMvn = 0xf << 21,
+    OpAnd = 0x0 << 21,
+    OpBic = 0xe << 21,
+    OpEor = 0x1 << 21,
+    OpOrr = 0xc << 21,
+    OpAdc = 0x5 << 21,
+    OpAdd = 0x4 << 21,
+    OpSbc = 0x6 << 21,
+    OpSub = 0x2 << 21,
+    OpRsb = 0x3 << 21,
+    OpRsc = 0x7 << 21,
+    OpCmn = 0xb << 21,
+    OpCmp = 0xa << 21,
+    OpTeq = 0x9 << 21,
+    OpTst = 0x8 << 21,
+    OpInvalid = -1
+};
+
+
+enum MULOp {
+    OpmMul   = 0 << 21,
+    OpmMla   = 1 << 21,
+    OpmUmaal = 2 << 21,
+    OpmMls   = 3 << 21,
+    OpmUmull = 4 << 21,
+    OpmUmlal = 5 << 21,
+    OpmSmull = 6 << 21,
+    OpmSmlal = 7 << 21
+};
+enum BranchTag {
+    OpB = 0x0a000000,
+    OpBMask = 0x0f000000,
+    OpBDestMask = 0x00ffffff,
+    OpBl = 0x0b000000,
+    OpBlx = 0x012fff30,
+    OpBx  = 0x012fff10
+};
+
+// Just like ALUOp, but for the vfp instruction set.
+enum VFPOp {
+    OpvMul  = 0x2 << 20,
+    OpvAdd  = 0x3 << 20,
+    OpvSub  = 0x3 << 20 | 0x1 << 6,
+    OpvDiv  = 0x8 << 20,
+    OpvMov  = 0xB << 20 | 0x1 << 6,
+    OpvAbs  = 0xB << 20 | 0x3 << 6,
+    OpvNeg  = 0xB << 20 | 0x1 << 6 | 0x1 << 16,
+    OpvSqrt = 0xB << 20 | 0x3 << 6 | 0x1 << 16,
+    OpvCmp  = 0xB << 20 | 0x1 << 6 | 0x4 << 16,
+    OpvCmpz  = 0xB << 20 | 0x1 << 6 | 0x5 << 16
+};
+
+// Negate the operation, AND negate the immediate that we were passed in.
+ALUOp ALUNeg(ALUOp op, Register dest, Register scratch, Imm32* imm, Register* negDest);
+bool can_dbl(ALUOp op);
+bool condsAreSafe(ALUOp op);
+
+// If there is a variant of op that has a dest (think cmp/sub) return that
+// variant of it.
+ALUOp getDestVariant(ALUOp op);
+
+static const ValueOperand JSReturnOperand = ValueOperand(JSReturnReg_Type, JSReturnReg_Data);
+static const ValueOperand softfpReturnOperand = ValueOperand(r1, r0);
+
+// All of these classes exist solely to shuffle data into the various operands.
+// For example Operand2 can be an imm8, a register-shifted-by-a-constant or a
+// register-shifted-by-a-register. We represent this in C++ by having a base
+// class Operand2, which just stores the 32 bits of data as they will be encoded
+// in the instruction. You cannot directly create an Operand2 since it is
+// tricky, and not entirely sane to do so. Instead, you create one of its child
+// classes, e.g. Imm8. Imm8's constructor takes a single integer argument. Imm8
+// will verify that its argument can be encoded as an ARM 12 bit imm8, encode it
+// using an Imm8data, and finally call its parent's (Operand2) constructor with
+// the Imm8data. The Operand2 constructor will then call the Imm8data's encode()
+// function to extract the raw bits from it.
+//
+// In the future, we should be able to extract data from the Operand2 by asking
+// it for its component Imm8data structures. The reason this is so horribly
+// round-about is we wanted to have Imm8 and RegisterShiftedRegister inherit
+// directly from Operand2 but have all of them take up only a single word of
+// storage. We also wanted to avoid passing around raw integers at all since
+// they are error prone.
+class Op2Reg;
+class O2RegImmShift;
+class O2RegRegShift;
+
+namespace datastore {
+
+class Reg
+{
+    // The "second register".
+    uint32_t rm_ : 4;
+    // Do we get another register for shifting.
+    bool rrs_ : 1;
+    ShiftType type_ : 2;
+    // We'd like this to be a more sensible encoding, but that would need to be
+    // a struct and that would not pack :(
+    uint32_t shiftAmount_ : 5;
+    uint32_t pad_ : 20;
+
+  public:
+    Reg(uint32_t rm, ShiftType type, uint32_t rsr, uint32_t shiftAmount)
+      : rm_(rm), rrs_(rsr), type_(type), shiftAmount_(shiftAmount), pad_(0)
+    { }
+    explicit Reg(const Op2Reg& op) {
+        memcpy(this, &op, sizeof(*this));
+    }
+
+    uint32_t shiftAmount() const {
+        return shiftAmount_;
+    }
+
+    uint32_t encode() const {
+        return rm_ | (rrs_ << 4) | (type_ << 5) | (shiftAmount_ << 7);
+    }
+};
+
+// Op2 has a mode labelled "<imm8m>", which is arm's magical immediate encoding.
+// Some instructions actually get 8 bits of data, which is called Imm8Data
+// below. These should have edit distance > 1, but this is how it is for now.
+class Imm8mData
+{
+    uint32_t data_ : 8;
+    uint32_t rot_ : 4;
+    uint32_t buff_ : 19;
+
+    // Throw in an extra bit that will be 1 if we can't encode this properly.
+    // if we can encode it properly, a simple "|" will still suffice to meld it
+    // into the instruction.
+    bool invalid_ : 1;
+
+  public:
+    // Default constructor makes an invalid immediate.
+    Imm8mData()
+      : data_(0xff), rot_(0xf), buff_(0), invalid_(true)
+    { }
+
+    Imm8mData(uint32_t data, uint32_t rot)
+      : data_(data), rot_(rot), buff_(0), invalid_(false)
+    {
+        MOZ_ASSERT(data == data_);
+        MOZ_ASSERT(rot == rot_);
+    }
+
+    bool invalid() const { return invalid_; }
+
+    uint32_t encode() const {
+        MOZ_ASSERT(!invalid_);
+        return data_ | (rot_ << 8);
+    };
+};
+
+class Imm8Data
+{
+    uint32_t imm4L_ : 4;
+    uint32_t pad_ : 4;
+    uint32_t imm4H_ : 4;
+
+  public:
+    explicit Imm8Data(uint32_t imm)
+      : imm4L_(imm & 0xf), imm4H_(imm >> 4)
+    {
+        MOZ_ASSERT(imm <= 0xff);
+    }
+
+    uint32_t encode() const {
+        return imm4L_ | (imm4H_ << 8);
+    };
+};
+
+// VLDR/VSTR take an 8 bit offset, which is implicitly left shifted by 2.
+class Imm8VFPOffData
+{
+    uint32_t data_;
+
+  public:
+    explicit Imm8VFPOffData(uint32_t imm)
+      : data_(imm)
+    {
+        MOZ_ASSERT((imm & ~(0xff)) == 0);
+    }
+    uint32_t encode() const {
+        return data_;
+    };
+};
+
+// ARM can magically encode 256 very special immediates to be moved into a
+// register.
+struct Imm8VFPImmData
+{
+    // This structure's members are public and it has no constructor to
+    // initialize them, for a very special reason. Were this structure to
+    // have a constructor, the initialization for DoubleEncoder's internal
+    // table (see below) would require a rather large static constructor on
+    // some of our supported compilers. The known solution to this is to mark
+    // the constructor constexpr, but, again, some of our supported
+    // compilers don't support constexpr! So we are reduced to public
+    // members and eschewing a constructor in hopes that the initialization
+    // of DoubleEncoder's table is correct.
+    uint32_t imm4L : 4;
+    uint32_t imm4H : 4;
+    int32_t isInvalid : 24;
+
+    uint32_t encode() const {
+        // This assert is an attempting at ensuring that we don't create random
+        // instances of this structure and then asking to encode() it.
+        MOZ_ASSERT(isInvalid == 0);
+        return imm4L | (imm4H << 16);
+    };
+};
+
+class Imm12Data
+{
+    uint32_t data_ : 12;
+
+  public:
+    explicit Imm12Data(uint32_t imm)
+      : data_(imm)
+    {
+        MOZ_ASSERT(data_ == imm);
+    }
+
+    uint32_t encode() const {
+        return data_;
+    }
+};
+
+class RIS
+{
+    uint32_t shiftAmount_ : 5;
+
+  public:
+    explicit RIS(uint32_t imm)
+      : shiftAmount_(imm)
+    {
+        MOZ_ASSERT(shiftAmount_ == imm);
+    }
+
+    explicit RIS(Reg r)
+      : shiftAmount_(r.shiftAmount())
+    { }
+
+    uint32_t encode() const {
+        return shiftAmount_;
+    }
+};
+
+class RRS
+{
+    bool mustZero_ : 1;
+    // The register that holds the shift amount.
+    uint32_t rs_ : 4;
+
+  public:
+    explicit RRS(uint32_t rs)
+      : rs_(rs)
+    {
+        MOZ_ASSERT(rs_ == rs);
+    }
+
+    uint32_t encode() const {
+        return rs_ << 1;
+    }
+};
+
+} // namespace datastore
+
+class MacroAssemblerARM;
+class Operand;
+
+class Operand2
+{
+    friend class Operand;
+    friend class MacroAssemblerARM;
+    friend class InstALU;
+
+    uint32_t oper_ : 31;
+    bool invalid_ : 1;
+
+  protected:
+    explicit Operand2(datastore::Imm8mData base)
+      : oper_(base.invalid() ? -1 : (base.encode() | uint32_t(IsImmOp2))),
+        invalid_(base.invalid())
+    { }
+
+    explicit Operand2(datastore::Reg base)
+      : oper_(base.encode() | uint32_t(IsNotImmOp2)),
+        invalid_(false)
+    { }
+
+  private:
+    explicit Operand2(uint32_t blob)
+      : oper_(blob),
+        invalid_(false)
+    { }
+
+  public:
+    bool isO2Reg() const {
+        return !(oper_ & IsImmOp2);
+    }
+
+    Op2Reg toOp2Reg() const;
+
+    bool isImm8() const {
+        return oper_ & IsImmOp2;
+    }
+
+    bool invalid() const {
+        return invalid_;
+    }
+
+    uint32_t encode() const {
+        return oper_;
+    }
+};
+
+class Imm8 : public Operand2
+{
+  public:
+    explicit Imm8(uint32_t imm)
+      : Operand2(EncodeImm(imm))
+    { }
+
+    static datastore::Imm8mData EncodeImm(uint32_t imm) {
+        // RotateLeft below may not be called with a shift of zero.
+        if (imm <= 0xFF)
+            return datastore::Imm8mData(imm, 0);
+
+        // An encodable integer has a maximum of 8 contiguous set bits,
+        // with an optional wrapped left rotation to even bit positions.
+        for (int rot = 1; rot < 16; rot++) {
+            uint32_t rotimm = mozilla::RotateLeft(imm, rot * 2);
+            if (rotimm <= 0xFF)
+                return datastore::Imm8mData(rotimm, rot);
+        }
+        return datastore::Imm8mData();
+    }
+
+    // Pair template?
+    struct TwoImm8mData
+    {
+        datastore::Imm8mData fst_, snd_;
+
+        TwoImm8mData() = default;
+
+        TwoImm8mData(datastore::Imm8mData fst, datastore::Imm8mData snd)
+          : fst_(fst), snd_(snd)
+        { }
+
+        datastore::Imm8mData fst() const { return fst_; }
+        datastore::Imm8mData snd() const { return snd_; }
+    };
+
+    static TwoImm8mData EncodeTwoImms(uint32_t);
+};
+
+class Op2Reg : public Operand2
+{
+  public:
+    explicit Op2Reg(Register rm, ShiftType type, datastore::RIS shiftImm)
+      : Operand2(datastore::Reg(rm.code(), type, 0, shiftImm.encode()))
+    { }
+
+    explicit Op2Reg(Register rm, ShiftType type, datastore::RRS shiftReg)
+      : Operand2(datastore::Reg(rm.code(), type, 1, shiftReg.encode()))
+    { }
+};
+
+static_assert(sizeof(Op2Reg) == sizeof(datastore::Reg),
+              "datastore::Reg(const Op2Reg&) constructor relies on Reg/Op2Reg having same size");
+
+class O2RegImmShift : public Op2Reg
+{
+  public:
+    explicit O2RegImmShift(Register rn, ShiftType type, uint32_t shift)
+      : Op2Reg(rn, type, datastore::RIS(shift))
+    { }
+};
+
+class O2RegRegShift : public Op2Reg
+{
+  public:
+    explicit O2RegRegShift(Register rn, ShiftType type, Register rs)
+      : Op2Reg(rn, type, datastore::RRS(rs.code()))
+    { }
+};
+
+O2RegImmShift O2Reg(Register r);
+O2RegImmShift lsl(Register r, int amt);
+O2RegImmShift lsr(Register r, int amt);
+O2RegImmShift asr(Register r, int amt);
+O2RegImmShift rol(Register r, int amt);
+O2RegImmShift ror(Register r, int amt);
+
+O2RegRegShift lsl(Register r, Register amt);
+O2RegRegShift lsr(Register r, Register amt);
+O2RegRegShift asr(Register r, Register amt);
+O2RegRegShift ror(Register r, Register amt);
+
+// An offset from a register to be used for ldr/str. This should include the
+// sign bit, since ARM has "signed-magnitude" offsets. That is it encodes an
+// unsigned offset, then the instruction specifies if the offset is positive or
+// negative. The +/- bit is necessary if the instruction set wants to be able to
+// have a negative register offset e.g. ldr pc, [r1,-r2];
+class DtrOff
+{
+    uint32_t data_;
+
+  protected:
+    explicit DtrOff(datastore::Imm12Data immdata, IsUp_ iu)
+      : data_(immdata.encode() | uint32_t(IsImmDTR) | uint32_t(iu))
+    { }
+
+    explicit DtrOff(datastore::Reg reg, IsUp_ iu = IsUp)
+      : data_(reg.encode() | uint32_t(IsNotImmDTR) | iu)
+    { }
+
+  public:
+    uint32_t encode() const { return data_; }
+};
+
+class DtrOffImm : public DtrOff
+{
+  public:
+    explicit DtrOffImm(int32_t imm)
+      : DtrOff(datastore::Imm12Data(mozilla::Abs(imm)), imm >= 0 ? IsUp : IsDown)
+    {
+        MOZ_ASSERT(mozilla::Abs(imm) < 4096);
+    }
+};
+
+class DtrOffReg : public DtrOff
+{
+    // These are designed to be called by a constructor of a subclass.
+    // Constructing the necessary RIS/RRS structures is annoying.
+
+  protected:
+    explicit DtrOffReg(Register rn, ShiftType type, datastore::RIS shiftImm, IsUp_ iu = IsUp)
+      : DtrOff(datastore::Reg(rn.code(), type, 0, shiftImm.encode()), iu)
+    { }
+
+    explicit DtrOffReg(Register rn, ShiftType type, datastore::RRS shiftReg, IsUp_ iu = IsUp)
+      : DtrOff(datastore::Reg(rn.code(), type, 1, shiftReg.encode()), iu)
+    { }
+};
+
+class DtrRegImmShift : public DtrOffReg
+{
+  public:
+    explicit DtrRegImmShift(Register rn, ShiftType type, uint32_t shift, IsUp_ iu = IsUp)
+      : DtrOffReg(rn, type, datastore::RIS(shift), iu)
+    { }
+};
+
+class DtrRegRegShift : public DtrOffReg
+{
+  public:
+    explicit DtrRegRegShift(Register rn, ShiftType type, Register rs, IsUp_ iu = IsUp)
+      : DtrOffReg(rn, type, datastore::RRS(rs.code()), iu)
+    { }
+};
+
+// We will frequently want to bundle a register with its offset so that we have
+// an "operand" to a load instruction.
+class DTRAddr
+{
+    friend class Operand;
+
+    uint32_t data_;
+
+  public:
+    explicit DTRAddr(Register reg, DtrOff dtr)
+      : data_(dtr.encode() | (reg.code() << 16))
+    { }
+
+    uint32_t encode() const {
+        return data_;
+    }
+
+    Register getBase() const {
+        return Register::FromCode((data_ >> 16) & 0xf);
+    }
+};
+
+// Offsets for the extended data transfer instructions:
+// ldrsh, ldrd, ldrsb, etc.
+class EDtrOff
+{
+    uint32_t data_;
+
+  protected:
+    explicit EDtrOff(datastore::Imm8Data imm8, IsUp_ iu = IsUp)
+      : data_(imm8.encode() | IsImmEDTR | uint32_t(iu))
+    { }
+
+    explicit EDtrOff(Register rm, IsUp_ iu = IsUp)
+      : data_(rm.code() | IsNotImmEDTR | iu)
+    { }
+
+  public:
+    uint32_t encode() const {
+        return data_;
+    }
+};
+
+class EDtrOffImm : public EDtrOff
+{
+  public:
+    explicit EDtrOffImm(int32_t imm)
+      : EDtrOff(datastore::Imm8Data(mozilla::Abs(imm)), (imm >= 0) ? IsUp : IsDown)
+    {
+        MOZ_ASSERT(mozilla::Abs(imm) < 256);
+    }
+};
+
+// This is the most-derived class, since the extended data transfer instructions
+// don't support any sort of modifying the "index" operand.
+class EDtrOffReg : public EDtrOff
+{
+  public:
+    explicit EDtrOffReg(Register rm)
+      : EDtrOff(rm)
+    { }
+};
+
+class EDtrAddr
+{
+    uint32_t data_;
+
+  public:
+    explicit EDtrAddr(Register r, EDtrOff off)
+      : data_(RN(r) | off.encode())
+    { }
+
+    uint32_t encode() const {
+        return data_;
+    }
+#ifdef DEBUG
+    Register maybeOffsetRegister() const {
+        if (data_ & IsImmEDTR)
+            return InvalidReg;
+        return Register::FromCode(data_ & 0xf);
+    }
+#endif
+};
+
+class VFPOff
+{
+    uint32_t data_;
+
+  protected:
+    explicit VFPOff(datastore::Imm8VFPOffData imm, IsUp_ isup)
+      : data_(imm.encode() | uint32_t(isup))
+    { }
+
+  public:
+    uint32_t encode() const {
+        return data_;
+    }
+};
+
+class VFPOffImm : public VFPOff
+{
+  public:
+    explicit VFPOffImm(int32_t imm)
+      : VFPOff(datastore::Imm8VFPOffData(mozilla::Abs(imm) / 4), imm < 0 ? IsDown : IsUp)
+    {
+        MOZ_ASSERT(mozilla::Abs(imm) <= 255 * 4);
+    }
+};
+
+class VFPAddr
+{
+    friend class Operand;
+
+    uint32_t data_;
+
+  public:
+    explicit VFPAddr(Register base, VFPOff off)
+      : data_(RN(base) | off.encode())
+    { }
+
+    uint32_t encode() const {
+        return data_;
+    }
+};
+
+class VFPImm
+{
+    uint32_t data_;
+
+  public:
+    explicit VFPImm(uint32_t topWordOfDouble);
+
+    static const VFPImm One;
+
+    uint32_t encode() const {
+        return data_;
+    }
+    bool isValid() const {
+        return data_ != -1U;
+    }
+};
+
+// A BOffImm is an immediate that is used for branches. Namely, it is the offset
+// that will be encoded in the branch instruction. This is the only sane way of
+// constructing a branch.
+class BOffImm
+{
+    friend class InstBranchImm;
+
+    uint32_t data_;
+
+  public:
+    explicit BOffImm(int offset)
+      : data_((offset - 8) >> 2 & 0x00ffffff)
+    {
+        MOZ_ASSERT((offset & 0x3) == 0);
+        if (!IsInRange(offset))
+            MOZ_CRASH("BOffImm offset out of range");
+    }
+
+    explicit BOffImm()
+      : data_(INVALID)
+    { }
+
+  private:
+    explicit BOffImm(const Instruction& inst);
+
+  public:
+    static const uint32_t INVALID = 0x00800000;
+
+    uint32_t encode() const {
+        return data_;
+    }
+    int32_t decode() const {
+        return ((int32_t(data_) << 8) >> 6) + 8;
+    }
+
+    static bool IsInRange(int offset) {
+        if ((offset - 8) < -33554432)
+            return false;
+        if ((offset - 8) > 33554428)
+            return false;
+        return true;
+    }
+
+    bool isInvalid() const {
+        return data_ == INVALID;
+    }
+    Instruction* getDest(Instruction* src) const;
+};
+
+class Imm16
+{
+    uint32_t lower_ : 12;
+    uint32_t pad_ : 4;
+    uint32_t upper_ : 4;
+    uint32_t invalid_ : 12;
+
+  public:
+    explicit Imm16();
+    explicit Imm16(uint32_t imm);
+    explicit Imm16(Instruction& inst);
+
+    uint32_t encode() const {
+        return lower_ | (upper_ << 16);
+    }
+    uint32_t decode() const {
+        return lower_ | (upper_ << 12);
+    }
+
+    bool isInvalid() const {
+        return invalid_;
+    }
+};
+
+// I would preffer that these do not exist, since there are essentially no
+// instructions that would ever take more than one of these, however, the MIR
+// wants to only have one type of arguments to functions, so bugger.
+class Operand
+{
+    // The encoding of registers is the same for OP2, DTR and EDTR yet the type
+    // system doesn't let us express this, so choices must be made.
+  public:
+    enum class Tag : uint8_t {
+        OP2,
+        MEM,
+        FOP
+    };
+
+  private:
+    Tag tag_ : 8;
+    uint32_t reg_ : 5;
+    int32_t offset_;
+
+  public:
+    explicit Operand(Register reg)
+      : tag_(Tag::OP2), reg_(reg.code())
+    { }
+
+    explicit Operand(FloatRegister freg)
+      : tag_(Tag::FOP), reg_(freg.code())
+    { }
+
+    explicit Operand(Register base, Imm32 off)
+      : tag_(Tag::MEM), reg_(base.code()), offset_(off.value)
+    { }
+
+    explicit Operand(Register base, int32_t off)
+      : tag_(Tag::MEM), reg_(base.code()), offset_(off)
+    { }
+
+    explicit Operand(const Address& addr)
+      : tag_(Tag::MEM), reg_(addr.base.code()), offset_(addr.offset)
+    { }
+
+  public:
+    Tag tag() const {
+        return tag_;
+    }
+
+    Operand2 toOp2() const {
+        MOZ_ASSERT(tag_ == Tag::OP2);
+        return O2Reg(Register::FromCode(reg_));
+    }
+
+    Register toReg() const {
+        MOZ_ASSERT(tag_ == Tag::OP2);
+        return Register::FromCode(reg_);
+    }
+
+    Address toAddress() const {
+        MOZ_ASSERT(tag_ == Tag::MEM);
+        return Address(Register::FromCode(reg_), offset_);
+    }
+    int32_t disp() const {
+        MOZ_ASSERT(tag_ == Tag::MEM);
+        return offset_;
+    }
+
+    int32_t base() const {
+        MOZ_ASSERT(tag_ == Tag::MEM);
+        return reg_;
+    }
+    Register baseReg() const {
+        MOZ_ASSERT(tag_ == Tag::MEM);
+        return Register::FromCode(reg_);
+    }
+    DTRAddr toDTRAddr() const {
+        MOZ_ASSERT(tag_ == Tag::MEM);
+        return DTRAddr(baseReg(), DtrOffImm(offset_));
+    }
+    VFPAddr toVFPAddr() const {
+        MOZ_ASSERT(tag_ == Tag::MEM);
+        return VFPAddr(baseReg(), VFPOffImm(offset_));
+    }
+};
+
+inline Imm32
+Imm64::firstHalf() const
+{
+    return low();
+}
+
+inline Imm32
+Imm64::secondHalf() const
+{
+    return hi();
+}
+
+void
+PatchJump(CodeLocationJump& jump_, CodeLocationLabel label,
+          ReprotectCode reprotect = DontReprotect);
+
+static inline void
+PatchBackedge(CodeLocationJump& jump_, CodeLocationLabel label, JitRuntime::BackedgeTarget target)
+{
+    PatchJump(jump_, label);
+}
+
+class InstructionIterator;
+class Assembler;
+typedef js::jit::AssemblerBufferWithConstantPools<1024, 4, Instruction, Assembler> ARMBuffer;
+
+class Assembler : public AssemblerShared
+{
+  public:
+    // ARM conditional constants:
+    enum ARMCondition {
+        EQ = 0x00000000, // Zero
+        NE = 0x10000000, // Non-zero
+        CS = 0x20000000,
+        CC = 0x30000000,
+        MI = 0x40000000,
+        PL = 0x50000000,
+        VS = 0x60000000,
+        VC = 0x70000000,
+        HI = 0x80000000,
+        LS = 0x90000000,
+        GE = 0xa0000000,
+        LT = 0xb0000000,
+        GT = 0xc0000000,
+        LE = 0xd0000000,
+        AL = 0xe0000000
+    };
+
+    enum Condition {
+        Equal = EQ,
+        NotEqual = NE,
+        Above = HI,
+        AboveOrEqual = CS,
+        Below = CC,
+        BelowOrEqual = LS,
+        GreaterThan = GT,
+        GreaterThanOrEqual = GE,
+        LessThan = LT,
+        LessThanOrEqual = LE,
+        Overflow = VS,
+        CarrySet = CS,
+        CarryClear = CC,
+        Signed = MI,
+        NotSigned = PL,
+        Zero = EQ,
+        NonZero = NE,
+        Always  = AL,
+
+        VFP_NotEqualOrUnordered = NE,
+        VFP_Equal = EQ,
+        VFP_Unordered = VS,
+        VFP_NotUnordered = VC,
+        VFP_GreaterThanOrEqualOrUnordered = CS,
+        VFP_GreaterThanOrEqual = GE,
+        VFP_GreaterThanOrUnordered = HI,
+        VFP_GreaterThan = GT,
+        VFP_LessThanOrEqualOrUnordered = LE,
+        VFP_LessThanOrEqual = LS,
+        VFP_LessThanOrUnordered = LT,
+        VFP_LessThan = CC // MI is valid too.
+    };
+
+    // Bit set when a DoubleCondition does not map to a single ARM condition.
+    // The macro assembler has to special-case these conditions, or else
+    // ConditionFromDoubleCondition will complain.
+    static const int DoubleConditionBitSpecial = 0x1;
+
+    enum DoubleCondition {
+        // These conditions will only evaluate to true if the comparison is
+        // ordered - i.e. neither operand is NaN.
+        DoubleOrdered = VFP_NotUnordered,
+        DoubleEqual = VFP_Equal,
+        DoubleNotEqual = VFP_NotEqualOrUnordered | DoubleConditionBitSpecial,
+        DoubleGreaterThan = VFP_GreaterThan,
+        DoubleGreaterThanOrEqual = VFP_GreaterThanOrEqual,
+        DoubleLessThan = VFP_LessThan,
+        DoubleLessThanOrEqual = VFP_LessThanOrEqual,
+        // If either operand is NaN, these conditions always evaluate to true.
+        DoubleUnordered = VFP_Unordered,
+        DoubleEqualOrUnordered = VFP_Equal | DoubleConditionBitSpecial,
+        DoubleNotEqualOrUnordered = VFP_NotEqualOrUnordered,
+        DoubleGreaterThanOrUnordered = VFP_GreaterThanOrUnordered,
+        DoubleGreaterThanOrEqualOrUnordered = VFP_GreaterThanOrEqualOrUnordered,
+        DoubleLessThanOrUnordered = VFP_LessThanOrUnordered,
+        DoubleLessThanOrEqualOrUnordered = VFP_LessThanOrEqualOrUnordered
+    };
+
+    Condition getCondition(uint32_t inst) {
+        return (Condition) (0xf0000000 & inst);
+    }
+    static inline Condition ConditionFromDoubleCondition(DoubleCondition cond) {
+        MOZ_ASSERT(!(cond & DoubleConditionBitSpecial));
+        return static_cast<Condition>(cond);
+    }
+
+    enum BarrierOption {
+        BarrierSY = 15,         // Full system barrier
+        BarrierST = 14          // StoreStore barrier
+    };
+
+    // This should be protected, but since CodeGenerator wants to use it, it
+    // needs to go out here :(
+
+    BufferOffset nextOffset() {
+        return m_buffer.nextOffset();
+    }
+
+  protected:
+    // Shim around AssemblerBufferWithConstantPools::allocEntry.
+    BufferOffset allocEntry(size_t numInst, unsigned numPoolEntries,
+                            uint8_t* inst, uint8_t* data, ARMBuffer::PoolEntry* pe = nullptr,
+                            bool markAsBranch = false, bool loadToPC = false);
+
+    Instruction* editSrc(BufferOffset bo) {
+        return m_buffer.getInst(bo);
+    }
+
+#ifdef JS_DISASM_ARM
+    static void spewInst(Instruction* i);
+    void spew(Instruction* i);
+    void spewBranch(Instruction* i, Label* target);
+    void spewData(BufferOffset addr, size_t numInstr, bool loadToPC);
+    void spewLabel(Label* label);
+    void spewRetarget(Label* label, Label* target);
+    void spewTarget(Label* l);
+#endif
+
+  public:
+    void resetCounter();
+    uint32_t actualIndex(uint32_t) const;
+    static uint8_t* PatchableJumpAddress(JitCode* code, uint32_t index);
+    static uint32_t NopFill;
+    static uint32_t GetNopFill();
+    static uint32_t AsmPoolMaxOffset;
+    static uint32_t GetPoolMaxOffset();
+
+  protected:
+    // Structure for fixing up pc-relative loads/jumps when a the machine code
+    // gets moved (executable copy, gc, etc.).
+    struct RelativePatch
+    {
+        void* target_;
+        Relocation::Kind kind_;
+
+      public:
+        RelativePatch(void* target, Relocation::Kind kind)
+          : target_(target), kind_(kind)
+        { }
+        void* target() const { return target_; }
+        Relocation::Kind kind() const { return kind_; }
+    };
+
+    // TODO: this should actually be a pool-like object. It is currently a big
+    // hack, and probably shouldn't exist.
+    js::Vector<RelativePatch, 8, SystemAllocPolicy> jumps_;
+
+    CompactBufferWriter jumpRelocations_;
+    CompactBufferWriter dataRelocations_;
+    CompactBufferWriter preBarriers_;
+
+    ARMBuffer m_buffer;
+
+#ifdef JS_DISASM_ARM
+  private:
+    class SpewNodes {
+        struct Node {
+            uint32_t key;
+            uint32_t value;
+            Node* next;
+        };
+
+        Node* nodes;
+
+    public:
+        SpewNodes() : nodes(nullptr) {}
+        ~SpewNodes();
+
+        bool lookup(uint32_t key, uint32_t* value);
+        bool add(uint32_t key, uint32_t value);
+        bool remove(uint32_t key);
+    };
+
+    SpewNodes spewNodes_;
+    uint32_t spewNext_;
+    Sprinter* printer_;
+
+    bool spewDisabled();
+    uint32_t spewResolve(Label* l);
+    uint32_t spewProbe(Label* l);
+    uint32_t spewDefine(Label* l);
+    void spew(const char* fmt, ...) MOZ_FORMAT_PRINTF(2, 3);
+    void spew(const char* fmt, va_list args);
+#endif
+
+  public:
+    // For the alignment fill use NOP: 0x0320f000 or (Always | InstNOP::NopInst).
+    // For the nopFill use a branch to the next instruction: 0xeaffffff.
+    Assembler()
+      : m_buffer(1, 1, 8, GetPoolMaxOffset(), 8, 0xe320f000, 0xeaffffff, GetNopFill()),
+#ifdef JS_DISASM_ARM
+        spewNext_(1000),
+        printer_(nullptr),
+#endif
+        isFinished(false),
+        dtmActive(false),
+        dtmCond(Always)
+    { }
+
+    // We need to wait until an AutoJitContextAlloc is created by the
+    // MacroAssembler, before allocating any space.
+    void initWithAllocator() {
+        m_buffer.initWithAllocator();
+    }
+
+    static Condition InvertCondition(Condition cond);
+    static Condition UnsignedCondition(Condition cond);
+    static Condition ConditionWithoutEqual(Condition cond);
+
+    // MacroAssemblers hold onto gcthings, so they are traced by the GC.
+    void trace(JSTracer* trc);
+    void writeRelocation(BufferOffset src) {
+        jumpRelocations_.writeUnsigned(src.getOffset());
+    }
+
+    // As opposed to x86/x64 version, the data relocation has to be executed
+    // before to recover the pointer, and not after.
+    void writeDataRelocation(ImmGCPtr ptr) {
+        if (ptr.value) {
+            if (gc::IsInsideNursery(ptr.value))
+                embedsNurseryPointers_ = true;
+            if (ptr.value)
+                dataRelocations_.writeUnsigned(nextOffset().getOffset());
+        }
+    }
+    void writePrebarrierOffset(CodeOffset label) {
+        preBarriers_.writeUnsigned(label.offset());
+    }
+
+    enum RelocBranchStyle {
+        B_MOVWT,
+        B_LDR_BX,
+        B_LDR,
+        B_MOVW_ADD
+    };
+
+    enum RelocStyle {
+        L_MOVWT,
+        L_LDR
+    };
+
+  public:
+    // Given the start of a Control Flow sequence, grab the value that is
+    // finally branched to given the start of a function that loads an address
+    // into a register get the address that ends up in the register.
+    template <class Iter>
+    static const uint32_t* GetCF32Target(Iter* iter);
+
+    static uintptr_t GetPointer(uint8_t*);
+    template <class Iter>
+    static const uint32_t* GetPtr32Target(Iter* iter, Register* dest = nullptr, RelocStyle* rs = nullptr);
+
+    bool oom() const;
+
+    void setPrinter(Sprinter* sp) {
+#ifdef JS_DISASM_ARM
+        printer_ = sp;
+#endif
+    }
+
+    static const Register getStackPointer() {
+        return StackPointer;
+    }
+
+  private:
+    bool isFinished;
+  public:
+    void finish();
+    bool asmMergeWith(Assembler& other);
+    void executableCopy(void* buffer);
+    void copyJumpRelocationTable(uint8_t* dest);
+    void copyDataRelocationTable(uint8_t* dest);
+    void copyPreBarrierTable(uint8_t* dest);
+
+    // Size of the instruction stream, in bytes, after pools are flushed.
+    size_t size() const;
+    // Size of the jump relocation table, in bytes.
+    size_t jumpRelocationTableBytes() const;
+    size_t dataRelocationTableBytes() const;
+    size_t preBarrierTableBytes() const;
+
+    // Size of the data table, in bytes.
+    size_t bytesNeeded() const;
+
+    // Write a blob of binary into the instruction stream *OR* into a
+    // destination address.
+    BufferOffset writeInst(uint32_t x);
+
+    // As above, but also mark the instruction as a branch.
+    BufferOffset writeBranchInst(uint32_t x, Label* documentation = nullptr);
+
+    // Write a placeholder NOP for a branch into the instruction stream
+    // (in order to adjust assembler addresses and mark it as a branch), it will
+    // be overwritten subsequently.
+    BufferOffset allocBranchInst();
+
+    // A static variant for the cases where we don't want to have an assembler
+    // object.
+    static void WriteInstStatic(uint32_t x, uint32_t* dest);
+
+  public:
+    void writeCodePointer(CodeOffset* label);
+
+    void haltingAlign(int alignment);
+    void nopAlign(int alignment);
+    BufferOffset as_nop();
+    BufferOffset as_alu(Register dest, Register src1, Operand2 op2,
+                        ALUOp op, SBit s = LeaveCC, Condition c = Always);
+    BufferOffset as_mov(Register dest,
+                        Operand2 op2, SBit s = LeaveCC, Condition c = Always);
+    BufferOffset as_mvn(Register dest, Operand2 op2,
+                        SBit s = LeaveCC, Condition c = Always);
+
+    static void as_alu_patch(Register dest, Register src1, Operand2 op2,
+                             ALUOp op, SBit s, Condition c, uint32_t* pos);
+    static void as_mov_patch(Register dest,
+                             Operand2 op2, SBit s, Condition c, uint32_t* pos);
+
+    // Logical operations:
+    BufferOffset as_and(Register dest, Register src1,
+                Operand2 op2, SBit s = LeaveCC, Condition c = Always);
+    BufferOffset as_bic(Register dest, Register src1,
+                Operand2 op2, SBit s = LeaveCC, Condition c = Always);
+    BufferOffset as_eor(Register dest, Register src1,
+                Operand2 op2, SBit s = LeaveCC, Condition c = Always);
+    BufferOffset as_orr(Register dest, Register src1,
+                Operand2 op2, SBit s = LeaveCC, Condition c = Always);
+    // Mathematical operations:
+    BufferOffset as_adc(Register dest, Register src1,
+                Operand2 op2, SBit s = LeaveCC, Condition c = Always);
+    BufferOffset as_add(Register dest, Register src1,
+                Operand2 op2, SBit s = LeaveCC, Condition c = Always);
+    BufferOffset as_sbc(Register dest, Register src1,
+                Operand2 op2, SBit s = LeaveCC, Condition c = Always);
+    BufferOffset as_sub(Register dest, Register src1,
+                Operand2 op2, SBit s = LeaveCC, Condition c = Always);
+    BufferOffset as_rsb(Register dest, Register src1,
+                Operand2 op2, SBit s = LeaveCC, Condition c = Always);
+    BufferOffset as_rsc(Register dest, Register src1,
+                Operand2 op2, SBit s = LeaveCC, Condition c = Always);
+    // Test operations:
+    BufferOffset as_cmn(Register src1, Operand2 op2, Condition c = Always);
+    BufferOffset as_cmp(Register src1, Operand2 op2, Condition c = Always);
+    BufferOffset as_teq(Register src1, Operand2 op2, Condition c = Always);
+    BufferOffset as_tst(Register src1, Operand2 op2, Condition c = Always);
+
+    // Sign extension operations:
+    BufferOffset as_sxtb(Register dest, Register src, int rotate, Condition c = Always);
+    BufferOffset as_sxth(Register dest, Register src, int rotate, Condition c = Always);
+    BufferOffset as_uxtb(Register dest, Register src, int rotate, Condition c = Always);
+    BufferOffset as_uxth(Register dest, Register src, int rotate, Condition c = Always);
+
+    // Not quite ALU worthy, but useful none the less: These also have the issue
+    // of these being formatted completly differently from the standard ALU operations.
+    BufferOffset as_movw(Register dest, Imm16 imm, Condition c = Always);
+    BufferOffset as_movt(Register dest, Imm16 imm, Condition c = Always);
+
+    static void as_movw_patch(Register dest, Imm16 imm, Condition c, Instruction* pos);
+    static void as_movt_patch(Register dest, Imm16 imm, Condition c, Instruction* pos);
+
+    BufferOffset as_genmul(Register d1, Register d2, Register rm, Register rn,
+                   MULOp op, SBit s, Condition c = Always);
+    BufferOffset as_mul(Register dest, Register src1, Register src2,
+                SBit s = LeaveCC, Condition c = Always);
+    BufferOffset as_mla(Register dest, Register acc, Register src1, Register src2,
+                SBit s = LeaveCC, Condition c = Always);
+    BufferOffset as_umaal(Register dest1, Register dest2, Register src1, Register src2,
+                  Condition c = Always);
+    BufferOffset as_mls(Register dest, Register acc, Register src1, Register src2,
+                Condition c = Always);
+    BufferOffset as_umull(Register dest1, Register dest2, Register src1, Register src2,
+                SBit s = LeaveCC, Condition c = Always);
+    BufferOffset as_umlal(Register dest1, Register dest2, Register src1, Register src2,
+                SBit s = LeaveCC, Condition c = Always);
+    BufferOffset as_smull(Register dest1, Register dest2, Register src1, Register src2,
+                SBit s = LeaveCC, Condition c = Always);
+    BufferOffset as_smlal(Register dest1, Register dest2, Register src1, Register src2,
+                SBit s = LeaveCC, Condition c = Always);
+
+    BufferOffset as_sdiv(Register dest, Register num, Register div, Condition c = Always);
+    BufferOffset as_udiv(Register dest, Register num, Register div, Condition c = Always);
+    BufferOffset as_clz(Register dest, Register src, Condition c = Always);
+
+    // Data transfer instructions: ldr, str, ldrb, strb.
+    // Using an int to differentiate between 8 bits and 32 bits is overkill.
+    BufferOffset as_dtr(LoadStore ls, int size, Index mode,
+                        Register rt, DTRAddr addr, Condition c = Always);
+
+    static void as_dtr_patch(LoadStore ls, int size, Index mode,
+                             Register rt, DTRAddr addr, Condition c, uint32_t* dest);
+
+    // Handles all of the other integral data transferring functions:
+    // ldrsb, ldrsh, ldrd, etc. The size is given in bits.
+    BufferOffset as_extdtr(LoadStore ls, int size, bool IsSigned, Index mode,
+                           Register rt, EDtrAddr addr, Condition c = Always);
+
+    BufferOffset as_dtm(LoadStore ls, Register rn, uint32_t mask,
+                DTMMode mode, DTMWriteBack wb, Condition c = Always);
+
+    // Overwrite a pool entry with new data.
+    static void WritePoolEntry(Instruction* addr, Condition c, uint32_t data);
+
+    // Load a 32 bit immediate from a pool into a register.
+    BufferOffset as_Imm32Pool(Register dest, uint32_t value, Condition c = Always);
+    // Make a patchable jump that can target the entire 32 bit address space.
+    BufferOffset as_BranchPool(uint32_t value, RepatchLabel* label,
+                               ARMBuffer::PoolEntry* pe = nullptr, Condition c = Always,
+                               Label* documentation = nullptr);
+
+    // Load a 64 bit floating point immediate from a pool into a register.
+    BufferOffset as_FImm64Pool(VFPRegister dest, wasm::RawF64 value, Condition c = Always);
+    // Load a 32 bit floating point immediate from a pool into a register.
+    BufferOffset as_FImm32Pool(VFPRegister dest, wasm::RawF32 value, Condition c = Always);
+
+    // Atomic instructions: ldrex, ldrexh, ldrexb, strex, strexh, strexb.
+    //
+    // The halfword and byte versions are available from ARMv6K forward.
+    //
+    // The word versions are available from ARMv6 forward and can be used to
+    // implement the halfword and byte versions on older systems.
+
+    // LDREX rt, [rn]
+    BufferOffset as_ldrex(Register rt, Register rn, Condition c = Always);
+    BufferOffset as_ldrexh(Register rt, Register rn, Condition c = Always);
+    BufferOffset as_ldrexb(Register rt, Register rn, Condition c = Always);
+
+    // STREX rd, rt, [rn].  Constraint: rd != rn, rd != rt.
+    BufferOffset as_strex(Register rd, Register rt, Register rn, Condition c = Always);
+    BufferOffset as_strexh(Register rd, Register rt, Register rn, Condition c = Always);
+    BufferOffset as_strexb(Register rd, Register rt, Register rn, Condition c = Always);
+
+    // Memory synchronization.
+    // These are available from ARMv7 forward.
+    BufferOffset as_dmb(BarrierOption option = BarrierSY);
+    BufferOffset as_dsb(BarrierOption option = BarrierSY);
+    BufferOffset as_isb();
+
+    // Memory synchronization for architectures before ARMv7.
+    BufferOffset as_dsb_trap();
+    BufferOffset as_dmb_trap();
+    BufferOffset as_isb_trap();
+
+    // Control flow stuff:
+
+    // bx can *only* branch to a register never to an immediate.
+    BufferOffset as_bx(Register r, Condition c = Always);
+
+    // Branch can branch to an immediate *or* to a register. Branches to
+    // immediates are pc relative, branches to registers are absolute.
+    BufferOffset as_b(BOffImm off, Condition c, Label* documentation = nullptr);
+
+    BufferOffset as_b(Label* l, Condition c = Always);
+    BufferOffset as_b(wasm::TrapDesc target, Condition c = Always);
+    BufferOffset as_b(BOffImm off, Condition c, BufferOffset inst);
+
+    // blx can go to either an immediate or a register. When blx'ing to a
+    // register, we change processor mode depending on the low bit of the
+    // register when blx'ing to an immediate, we *always* change processor
+    // state.
+    BufferOffset as_blx(Label* l);
+
+    BufferOffset as_blx(Register r, Condition c = Always);
+    BufferOffset as_bl(BOffImm off, Condition c, Label* documentation = nullptr);
+    // bl can only branch+link to an immediate, never to a register it never
+    // changes processor state.
+    BufferOffset as_bl();
+    // bl #imm can have a condition code, blx #imm cannot.
+    // blx reg can be conditional.
+    BufferOffset as_bl(Label* l, Condition c);
+    BufferOffset as_bl(BOffImm off, Condition c, BufferOffset inst);
+
+    BufferOffset as_mrs(Register r, Condition c = Always);
+    BufferOffset as_msr(Register r, Condition c = Always);
+
+    // VFP instructions!
+  private:
+    enum vfp_size {
+        IsDouble = 1 << 8,
+        IsSingle = 0 << 8
+    };
+
+    BufferOffset writeVFPInst(vfp_size sz, uint32_t blob);
+
+    static void WriteVFPInstStatic(vfp_size sz, uint32_t blob, uint32_t* dest);
+
+    // Unityped variants: all registers hold the same (ieee754 single/double)
+    // notably not included are vcvt; vmov vd, #imm; vmov rt, vn.
+    BufferOffset as_vfp_float(VFPRegister vd, VFPRegister vn, VFPRegister vm,
+                              VFPOp op, Condition c = Always);
+
+  public:
+    BufferOffset as_vadd(VFPRegister vd, VFPRegister vn, VFPRegister vm, Condition c = Always);
+    BufferOffset as_vdiv(VFPRegister vd, VFPRegister vn, VFPRegister vm, Condition c = Always);
+    BufferOffset as_vmul(VFPRegister vd, VFPRegister vn, VFPRegister vm, Condition c = Always);
+    BufferOffset as_vnmul(VFPRegister vd, VFPRegister vn, VFPRegister vm, Condition c = Always);
+    BufferOffset as_vnmla(VFPRegister vd, VFPRegister vn, VFPRegister vm, Condition c = Always);
+    BufferOffset as_vnmls(VFPRegister vd, VFPRegister vn, VFPRegister vm, Condition c = Always);
+    BufferOffset as_vneg(VFPRegister vd, VFPRegister vm, Condition c = Always);
+    BufferOffset as_vsqrt(VFPRegister vd, VFPRegister vm, Condition c = Always);
+    BufferOffset as_vabs(VFPRegister vd, VFPRegister vm, Condition c = Always);
+    BufferOffset as_vsub(VFPRegister vd, VFPRegister vn, VFPRegister vm, Condition c = Always);
+    BufferOffset as_vcmp(VFPRegister vd, VFPRegister vm, Condition c = Always);
+    BufferOffset as_vcmpz(VFPRegister vd,  Condition c = Always);
+
+    // Specifically, a move between two same sized-registers.
+    BufferOffset as_vmov(VFPRegister vd, VFPRegister vsrc, Condition c = Always);
+
+    // Transfer between Core and VFP.
+    enum FloatToCore_ {
+        FloatToCore = 1 << 20,
+        CoreToFloat = 0 << 20
+    };
+
+  private:
+    enum VFPXferSize {
+        WordTransfer   = 0x02000010,
+        DoubleTransfer = 0x00400010
+    };
+
+  public:
+    // Unlike the next function, moving between the core registers and vfp
+    // registers can't be *that* properly typed. Namely, since I don't want to
+    // munge the type VFPRegister to also include core registers. Thus, the core
+    // and vfp registers are passed in based on their type, and src/dest is
+    // determined by the float2core.
+
+    BufferOffset as_vxfer(Register vt1, Register vt2, VFPRegister vm, FloatToCore_ f2c,
+                  Condition c = Always, int idx = 0);
+
+    // Our encoding actually allows just the src and the dest (and their types)
+    // to uniquely specify the encoding that we are going to use.
+    BufferOffset as_vcvt(VFPRegister vd, VFPRegister vm, bool useFPSCR = false,
+                         Condition c = Always);
+
+    // Hard coded to a 32 bit fixed width result for now.
+    BufferOffset as_vcvtFixed(VFPRegister vd, bool isSigned, uint32_t fixedPoint,
+                              bool toFixed, Condition c = Always);
+
+    // Transfer between VFP and memory.
+    BufferOffset as_vdtr(LoadStore ls, VFPRegister vd, VFPAddr addr,
+                         Condition c = Always /* vfp doesn't have a wb option*/);
+
+    static void as_vdtr_patch(LoadStore ls, VFPRegister vd, VFPAddr addr,
+                              Condition c /* vfp doesn't have a wb option */, uint32_t* dest);
+
+    // VFP's ldm/stm work differently from the standard arm ones. You can only
+    // transfer a range.
+
+    BufferOffset as_vdtm(LoadStore st, Register rn, VFPRegister vd, int length,
+                 /* also has update conditions */ Condition c = Always);
+
+    BufferOffset as_vimm(VFPRegister vd, VFPImm imm, Condition c = Always);
+
+    BufferOffset as_vmrs(Register r, Condition c = Always);
+    BufferOffset as_vmsr(Register r, Condition c = Always);
+
+    // Label operations.
+    bool nextLink(BufferOffset b, BufferOffset* next);
+    void bind(Label* label, BufferOffset boff = BufferOffset());
+    void bind(RepatchLabel* label);
+    void bindLater(Label* label, wasm::TrapDesc target);
+    uint32_t currentOffset() {
+        return nextOffset().getOffset();
+    }
+    void retarget(Label* label, Label* target);
+    // I'm going to pretend this doesn't exist for now.
+    void retarget(Label* label, void* target, Relocation::Kind reloc);
+
+    void Bind(uint8_t* rawCode, CodeOffset* label, const void* address);
+
+    // See Bind
+    size_t labelToPatchOffset(CodeOffset label) {
+        return label.offset();
+    }
+
+    void as_bkpt();
+
+  public:
+    static void TraceJumpRelocations(JSTracer* trc, JitCode* code, CompactBufferReader& reader);
+    static void TraceDataRelocations(JSTracer* trc, JitCode* code, CompactBufferReader& reader);
+
+    static bool SupportsFloatingPoint() {
+        return HasVFP();
+    }
+    static bool SupportsUnalignedAccesses() {
+        return HasARMv7();
+    }
+    static bool SupportsSimd() {
+        return js::jit::SupportsSimd;
+    }
+
+  protected:
+    void addPendingJump(BufferOffset src, ImmPtr target, Relocation::Kind kind) {
+        enoughMemory_ &= jumps_.append(RelativePatch(target.value, kind));
+        if (kind == Relocation::JITCODE)
+            writeRelocation(src);
+    }
+
+  public:
+    // The buffer is about to be linked, make sure any constant pools or excess
+    // bookkeeping has been flushed to the instruction stream.
+    void flush() {
+        MOZ_ASSERT(!isFinished);
+        m_buffer.flushPool();
+        return;
+    }
+
+    void comment(const char* msg) {
+#ifdef JS_DISASM_ARM
+        spew("; %s", msg);
+#endif
+    }
+
+    // Copy the assembly code to the given buffer, and perform any pending
+    // relocations relying on the target address.
+    void executableCopy(uint8_t* buffer);
+
+    // Actual assembly emitting functions.
+
+    // Since I can't think of a reasonable default for the mode, I'm going to
+    // leave it as a required argument.
+    void startDataTransferM(LoadStore ls, Register rm,
+                            DTMMode mode, DTMWriteBack update = NoWriteBack,
+                            Condition c = Always)
+    {
+        MOZ_ASSERT(!dtmActive);
+        dtmUpdate = update;
+        dtmBase = rm;
+        dtmLoadStore = ls;
+        dtmLastReg = -1;
+        dtmRegBitField = 0;
+        dtmActive = 1;
+        dtmCond = c;
+        dtmMode = mode;
+    }
+
+    void transferReg(Register rn) {
+        MOZ_ASSERT(dtmActive);
+        MOZ_ASSERT(rn.code() > dtmLastReg);
+        dtmRegBitField |= 1 << rn.code();
+        if (dtmLoadStore == IsLoad && rn.code() == 13 && dtmBase.code() == 13) {
+            MOZ_CRASH("ARM Spec says this is invalid");
+        }
+    }
+    void finishDataTransfer() {
+        dtmActive = false;
+        as_dtm(dtmLoadStore, dtmBase, dtmRegBitField, dtmMode, dtmUpdate, dtmCond);
+    }
+
+    void startFloatTransferM(LoadStore ls, Register rm,
+                             DTMMode mode, DTMWriteBack update = NoWriteBack,
+                             Condition c = Always)
+    {
+        MOZ_ASSERT(!dtmActive);
+        dtmActive = true;
+        dtmUpdate = update;
+        dtmLoadStore = ls;
+        dtmBase = rm;
+        dtmCond = c;
+        dtmLastReg = -1;
+        dtmMode = mode;
+        dtmDelta = 0;
+    }
+    void transferFloatReg(VFPRegister rn)
+    {
+        if (dtmLastReg == -1) {
+            vdtmFirstReg = rn.code();
+        } else {
+            if (dtmDelta == 0) {
+                dtmDelta = rn.code() - dtmLastReg;
+                MOZ_ASSERT(dtmDelta == 1 || dtmDelta == -1);
+            }
+            MOZ_ASSERT(dtmLastReg >= 0);
+            MOZ_ASSERT(rn.code() == unsigned(dtmLastReg) + dtmDelta);
+        }
+
+        dtmLastReg = rn.code();
+    }
+    void finishFloatTransfer() {
+        MOZ_ASSERT(dtmActive);
+        dtmActive = false;
+        MOZ_ASSERT(dtmLastReg != -1);
+        dtmDelta = dtmDelta ? dtmDelta : 1;
+        // The operand for the vstr/vldr instruction is the lowest register in the range.
+        int low = Min(dtmLastReg, vdtmFirstReg);
+        int high = Max(dtmLastReg, vdtmFirstReg);
+        // Fencepost problem.
+        int len = high - low + 1;
+        // vdtm can only transfer 16 registers at once.  If we need to transfer more,
+        // then either hoops are necessary, or we need to be updating the register.
+        MOZ_ASSERT_IF(len > 16, dtmUpdate == WriteBack);
+
+        int adjustLow = dtmLoadStore == IsStore ? 0 : 1;
+        int adjustHigh = dtmLoadStore == IsStore ? -1 : 0;
+        while (len > 0) {
+            // Limit the instruction to 16 registers.
+            int curLen = Min(len, 16);
+            // If it is a store, we want to start at the high end and move down
+            // (e.g. vpush d16-d31; vpush d0-d15).
+            int curStart = (dtmLoadStore == IsStore) ? high - curLen + 1 : low;
+            as_vdtm(dtmLoadStore, dtmBase,
+                    VFPRegister(FloatRegister::FromCode(curStart)),
+                    curLen, dtmCond);
+            // Update the bounds.
+            low += adjustLow * curLen;
+            high += adjustHigh * curLen;
+            // Update the length parameter.
+            len -= curLen;
+        }
+    }
+
+  private:
+    int dtmRegBitField;
+    int vdtmFirstReg;
+    int dtmLastReg;
+    int dtmDelta;
+    Register dtmBase;
+    DTMWriteBack dtmUpdate;
+    DTMMode dtmMode;
+    LoadStore dtmLoadStore;
+    bool dtmActive;
+    Condition dtmCond;
+
+  public:
+    enum {
+        PadForAlign8  = (int)0x00,
+        PadForAlign16 = (int)0x0000,
+        PadForAlign32 = (int)0xe12fff7f  // 'bkpt 0xffff'
+    };
+
+    // API for speaking with the IonAssemblerBufferWithConstantPools generate an
+    // initial placeholder instruction that we want to later fix up.
+    static void InsertIndexIntoTag(uint8_t* load, uint32_t index);
+
+    // Take the stub value that was written in before, and write in an actual
+    // load using the index we'd computed previously as well as the address of
+    // the pool start.
+    static void PatchConstantPoolLoad(void* loadAddr, void* constPoolAddr);
+
+    // We're not tracking short-range branches for ARM for now.
+    static void PatchShortRangeBranchToVeneer(ARMBuffer*, unsigned rangeIdx, BufferOffset deadline,
+                                              BufferOffset veneer)
+    {
+        MOZ_CRASH();
+    }
+    // END API
+
+    // Move our entire pool into the instruction stream. This is to force an
+    // opportunistic dump of the pool, prefferably when it is more convenient to
+    // do a dump.
+    void flushBuffer();
+    void enterNoPool(size_t maxInst);
+    void leaveNoPool();
+    // This should return a BOffImm, but we didn't want to require everyplace
+    // that used the AssemblerBuffer to make that class.
+    static ptrdiff_t GetBranchOffset(const Instruction* i);
+    static void RetargetNearBranch(Instruction* i, int offset, Condition cond, bool final = true);
+    static void RetargetNearBranch(Instruction* i, int offset, bool final = true);
+    static void RetargetFarBranch(Instruction* i, uint8_t** slot, uint8_t* dest, Condition cond);
+
+    static void WritePoolHeader(uint8_t* start, Pool* p, bool isNatural);
+    static void WritePoolGuard(BufferOffset branch, Instruction* inst, BufferOffset dest);
+
+
+    static uint32_t PatchWrite_NearCallSize();
+    static uint32_t NopSize() { return 4; }
+    static void PatchWrite_NearCall(CodeLocationLabel start, CodeLocationLabel toCall);
+    static void PatchDataWithValueCheck(CodeLocationLabel label, PatchedImmPtr newValue,
+                                        PatchedImmPtr expectedValue);
+    static void PatchDataWithValueCheck(CodeLocationLabel label, ImmPtr newValue,
+                                        ImmPtr expectedValue);
+    static void PatchWrite_Imm32(CodeLocationLabel label, Imm32 imm);
+
+    static void PatchInstructionImmediate(uint8_t* code, PatchedImmPtr imm) {
+        MOZ_CRASH("Unused.");
+    }
+
+    static uint32_t AlignDoubleArg(uint32_t offset) {
+        return (offset + 1) & ~1;
+    }
+    static uint8_t* NextInstruction(uint8_t* instruction, uint32_t* count = nullptr);
+
+    // Toggle a jmp or cmp emitted by toggledJump().
+    static void ToggleToJmp(CodeLocationLabel inst_);
+    static void ToggleToCmp(CodeLocationLabel inst_);
+
+    static uint8_t* BailoutTableStart(uint8_t* code);
+
+    static size_t ToggledCallSize(uint8_t* code);
+    static void ToggleCall(CodeLocationLabel inst_, bool enabled);
+
+    void processCodeLabels(uint8_t* rawCode);
+
+    bool bailed() {
+        return m_buffer.bail();
+    }
+
+    void verifyHeapAccessDisassembly(uint32_t begin, uint32_t end,
+                                     const Disassembler::HeapAccess& heapAccess)
+    {
+        // Implement this if we implement a disassembler.
+    }
+}; // Assembler
+
+// An Instruction is a structure for both encoding and decoding any and all ARM
+// instructions. Many classes have not been implemented thus far.
+class Instruction
+{
+    uint32_t data;
+
+  protected:
+    // This is not for defaulting to always, this is for instructions that
+    // cannot be made conditional, and have the usually invalid 4b1111 cond
+    // field.
+    explicit Instruction(uint32_t data_, bool fake = false)
+      : data(data_ | 0xf0000000)
+    {
+        MOZ_ASSERT(fake || ((data_ & 0xf0000000) == 0));
+    }
+    // Standard constructor.
+    Instruction(uint32_t data_, Assembler::Condition c)
+      : data(data_ | (uint32_t) c)
+    {
+        MOZ_ASSERT((data_ & 0xf0000000) == 0);
+    }
+    // You should never create an instruction directly. You should create a more
+    // specific instruction which will eventually call one of these constructors
+    // for you.
+  public:
+    uint32_t encode() const {
+        return data;
+    }
+    // Check if this instruction is really a particular case.
+    template <class C>
+    bool is() const { return C::IsTHIS(*this); }
+
+    // Safely get a more specific variant of this pointer.
+    template <class C>
+    C* as() const { return C::AsTHIS(*this); }
+
+    const Instruction& operator=(Instruction src) {
+        data = src.data;
+        return *this;
+    }
+    // Since almost all instructions have condition codes, the condition code
+    // extractor resides in the base class.
+    Assembler::Condition extractCond() {
+        MOZ_ASSERT(data >> 28 != 0xf, "The instruction does not have condition code");
+        return (Assembler::Condition)(data & 0xf0000000);
+    }
+    // Get the next instruction in the instruction stream.
+    // This does neat things like ignoreconstant pools and their guards.
+    Instruction* next();
+
+    // Skipping pools with artificial guards.
+    Instruction* skipPool();
+
+    // Sometimes, an api wants a uint32_t (or a pointer to it) rather than an
+    // instruction. raw() just coerces this into a pointer to a uint32_t.
+    const uint32_t* raw() const { return &data; }
+    uint32_t size() const { return 4; }
+}; // Instruction
+
+// Make sure that it is the right size.
+JS_STATIC_ASSERT(sizeof(Instruction) == 4);
+
+// Data Transfer Instructions.
+class InstDTR : public Instruction
+{
+  public:
+    enum IsByte_ {
+        IsByte = 0x00400000,
+        IsWord = 0x00000000
+    };
+    static const int IsDTR     = 0x04000000;
+    static const int IsDTRMask = 0x0c000000;
+
+    // TODO: Replace the initialization with something that is safer.
+    InstDTR(LoadStore ls, IsByte_ ib, Index mode, Register rt, DTRAddr addr, Assembler::Condition c)
+      : Instruction(ls | ib | mode | RT(rt) | addr.encode() | IsDTR, c)
+    { }
+
+    static bool IsTHIS(const Instruction& i);
+    static InstDTR* AsTHIS(const Instruction& i);
+
+};
+JS_STATIC_ASSERT(sizeof(InstDTR) == sizeof(Instruction));
+
+class InstLDR : public InstDTR
+{
+  public:
+    InstLDR(Index mode, Register rt, DTRAddr addr, Assembler::Condition c)
+      : InstDTR(IsLoad, IsWord, mode, rt, addr, c)
+    { }
+
+    static bool IsTHIS(const Instruction& i);
+    static InstLDR* AsTHIS(const Instruction& i);
+
+    int32_t signedOffset() const {
+        int32_t offset = encode() & 0xfff;
+        if (IsUp_(encode() & IsUp) != IsUp)
+            return -offset;
+        return offset;
+    }
+    uint32_t* dest() const {
+        int32_t offset = signedOffset();
+        // When patching the load in PatchConstantPoolLoad, we ensure that the
+        // offset is a multiple of 4, offset by 8 bytes from the actual
+        // location.  Indeed, when the base register is PC, ARM's 3 stages
+        // pipeline design makes it that PC is off by 8 bytes (= 2 *
+        // sizeof(uint32*)) when we actually executed it.
+        MOZ_ASSERT(offset % 4 == 0);
+        offset >>= 2;
+        return (uint32_t*)raw() + offset + 2;
+    }
+};
+JS_STATIC_ASSERT(sizeof(InstDTR) == sizeof(InstLDR));
+
+class InstNOP : public Instruction
+{
+  public:
+    static const uint32_t NopInst = 0x0320f000;
+
+    InstNOP()
+      : Instruction(NopInst, Assembler::Always)
+    { }
+
+    static bool IsTHIS(const Instruction& i);
+    static InstNOP* AsTHIS(Instruction& i);
+};
+
+// Branching to a register, or calling a register
+class InstBranchReg : public Instruction
+{
+  protected:
+    // Don't use BranchTag yourself, use a derived instruction.
+    enum BranchTag {
+        IsBX  = 0x012fff10,
+        IsBLX = 0x012fff30
+    };
+
+    static const uint32_t IsBRegMask = 0x0ffffff0;
+
+    InstBranchReg(BranchTag tag, Register rm, Assembler::Condition c)
+      : Instruction(tag | rm.code(), c)
+    { }
+
+  public:
+    static bool IsTHIS (const Instruction& i);
+    static InstBranchReg* AsTHIS (const Instruction& i);
+
+    // Get the register that is being branched to
+    void extractDest(Register* dest);
+    // Make sure we are branching to a pre-known register
+    bool checkDest(Register dest);
+};
+JS_STATIC_ASSERT(sizeof(InstBranchReg) == sizeof(Instruction));
+
+// Branching to an immediate offset, or calling an immediate offset
+class InstBranchImm : public Instruction
+{
+  protected:
+    enum BranchTag {
+        IsB   = 0x0a000000,
+        IsBL  = 0x0b000000
+    };
+
+    static const uint32_t IsBImmMask = 0x0f000000;
+
+    InstBranchImm(BranchTag tag, BOffImm off, Assembler::Condition c)
+      : Instruction(tag | off.encode(), c)
+    { }
+
+  public:
+    static bool IsTHIS (const Instruction& i);
+    static InstBranchImm* AsTHIS (const Instruction& i);
+
+    void extractImm(BOffImm* dest);
+};
+JS_STATIC_ASSERT(sizeof(InstBranchImm) == sizeof(Instruction));
+
+// Very specific branching instructions.
+class InstBXReg : public InstBranchReg
+{
+  public:
+    static bool IsTHIS (const Instruction& i);
+    static InstBXReg* AsTHIS (const Instruction& i);
+};
+
+class InstBLXReg : public InstBranchReg
+{
+  public:
+    InstBLXReg(Register reg, Assembler::Condition c)
+      : InstBranchReg(IsBLX, reg, c)
+    { }
+
+    static bool IsTHIS (const Instruction& i);
+    static InstBLXReg* AsTHIS (const Instruction& i);
+};
+
+class InstBImm : public InstBranchImm
+{
+  public:
+    InstBImm(BOffImm off, Assembler::Condition c)
+      : InstBranchImm(IsB, off, c)
+    { }
+
+    static bool IsTHIS (const Instruction& i);
+    static InstBImm* AsTHIS (const Instruction& i);
+};
+
+class InstBLImm : public InstBranchImm
+{
+  public:
+    InstBLImm(BOffImm off, Assembler::Condition c)
+      : InstBranchImm(IsBL, off, c)
+    { }
+
+    static bool IsTHIS (const Instruction& i);
+    static InstBLImm* AsTHIS (const Instruction& i);
+};
+
+// Both movw and movt. The layout of both the immediate and the destination
+// register is the same so the code is being shared.
+class InstMovWT : public Instruction
+{
+  protected:
+    enum WT {
+        IsW = 0x03000000,
+        IsT = 0x03400000
+    };
+    static const uint32_t IsWTMask = 0x0ff00000;
+
+    InstMovWT(Register rd, Imm16 imm, WT wt, Assembler::Condition c)
+      : Instruction (RD(rd) | imm.encode() | wt, c)
+    { }
+
+  public:
+    void extractImm(Imm16* dest);
+    void extractDest(Register* dest);
+    bool checkImm(Imm16 dest);
+    bool checkDest(Register dest);
+
+    static bool IsTHIS (Instruction& i);
+    static InstMovWT* AsTHIS (Instruction& i);
+
+};
+JS_STATIC_ASSERT(sizeof(InstMovWT) == sizeof(Instruction));
+
+class InstMovW : public InstMovWT
+{
+  public:
+    InstMovW (Register rd, Imm16 imm, Assembler::Condition c)
+      : InstMovWT(rd, imm, IsW, c)
+    { }
+
+    static bool IsTHIS (const Instruction& i);
+    static InstMovW* AsTHIS (const Instruction& i);
+};
+
+class InstMovT : public InstMovWT
+{
+  public:
+    InstMovT (Register rd, Imm16 imm, Assembler::Condition c)
+      : InstMovWT(rd, imm, IsT, c)
+    { }
+
+    static bool IsTHIS (const Instruction& i);
+    static InstMovT* AsTHIS (const Instruction& i);
+};
+
+class InstALU : public Instruction
+{
+    static const int32_t ALUMask = 0xc << 24;
+
+  public:
+    InstALU(Register rd, Register rn, Operand2 op2, ALUOp op, SBit s, Assembler::Condition c)
+      : Instruction(maybeRD(rd) | maybeRN(rn) | op2.encode() | op | s, c)
+    { }
+
+    static bool IsTHIS (const Instruction& i);
+    static InstALU* AsTHIS (const Instruction& i);
+
+    void extractOp(ALUOp* ret);
+    bool checkOp(ALUOp op);
+    void extractDest(Register* ret);
+    bool checkDest(Register rd);
+    void extractOp1(Register* ret);
+    bool checkOp1(Register rn);
+    Operand2 extractOp2();
+};
+
+class InstCMP : public InstALU
+{
+  public:
+    static bool IsTHIS (const Instruction& i);
+    static InstCMP* AsTHIS (const Instruction& i);
+};
+
+class InstMOV : public InstALU
+{
+  public:
+    static bool IsTHIS (const Instruction& i);
+    static InstMOV* AsTHIS (const Instruction& i);
+};
+
+
+class InstructionIterator
+{
+  private:
+    Instruction* i;
+
+  public:
+    explicit InstructionIterator(Instruction* i_);
+
+    Instruction* next() {
+        i = i->next();
+        return cur();
+    }
+    Instruction* cur() const {
+        return i;
+    }
+};
+
+static const uint32_t NumIntArgRegs = 4;
+
+// There are 16 *float* registers available for arguments
+// If doubles are used, only half the number of registers are available.
+static const uint32_t NumFloatArgRegs = 16;
+
+static inline bool
+GetIntArgReg(uint32_t usedIntArgs, uint32_t usedFloatArgs, Register* out)
+{
+    if (usedIntArgs >= NumIntArgRegs)
+        return false;
+
+    *out = Register::FromCode(usedIntArgs);
+    return true;
+}
+
+// Get a register in which we plan to put a quantity that will be used as an
+// integer argument. This differs from GetIntArgReg in that if we have no more
+// actual argument registers to use we will fall back on using whatever
+// CallTempReg* don't overlap the argument registers, and only fail once those
+// run out too.
+static inline bool
+GetTempRegForIntArg(uint32_t usedIntArgs, uint32_t usedFloatArgs, Register* out)
+{
+    if (GetIntArgReg(usedIntArgs, usedFloatArgs, out))
+        return true;
+
+    // Unfortunately, we have to assume things about the point at which
+    // GetIntArgReg returns false, because we need to know how many registers it
+    // can allocate.
+    usedIntArgs -= NumIntArgRegs;
+    if (usedIntArgs >= NumCallTempNonArgRegs)
+        return false;
+
+    *out = CallTempNonArgRegs[usedIntArgs];
+    return true;
+}
+
+
+#if !defined(JS_CODEGEN_ARM_HARDFP) || defined(JS_SIMULATOR_ARM)
+
+static inline uint32_t
+GetArgStackDisp(uint32_t arg)
+{
+    MOZ_ASSERT(!UseHardFpABI());
+    MOZ_ASSERT(arg >= NumIntArgRegs);
+    return (arg - NumIntArgRegs) * sizeof(intptr_t);
+}
+
+#endif
+
+
+#if defined(JS_CODEGEN_ARM_HARDFP) || defined(JS_SIMULATOR_ARM)
+
+static inline bool
+GetFloat32ArgReg(uint32_t usedIntArgs, uint32_t usedFloatArgs, FloatRegister* out)
+{
+    MOZ_ASSERT(UseHardFpABI());
+    if (usedFloatArgs >= NumFloatArgRegs)
+        return false;
+    *out = VFPRegister(usedFloatArgs, VFPRegister::Single);
+    return true;
+}
+static inline bool
+GetDoubleArgReg(uint32_t usedIntArgs, uint32_t usedFloatArgs, FloatRegister* out)
+{
+    MOZ_ASSERT(UseHardFpABI());
+    MOZ_ASSERT((usedFloatArgs % 2) == 0);
+    if (usedFloatArgs >= NumFloatArgRegs)
+        return false;
+    *out = VFPRegister(usedFloatArgs>>1, VFPRegister::Double);
+    return true;
+}
+
+static inline uint32_t
+GetIntArgStackDisp(uint32_t usedIntArgs, uint32_t usedFloatArgs, uint32_t* padding)
+{
+    MOZ_ASSERT(UseHardFpABI());
+    MOZ_ASSERT(usedIntArgs >= NumIntArgRegs);
+    uint32_t doubleSlots = Max(0, (int32_t)usedFloatArgs - (int32_t)NumFloatArgRegs);
+    doubleSlots *= 2;
+    int intSlots = usedIntArgs - NumIntArgRegs;
+    return (intSlots + doubleSlots + *padding) * sizeof(intptr_t);
+}
+
+static inline uint32_t
+GetFloat32ArgStackDisp(uint32_t usedIntArgs, uint32_t usedFloatArgs, uint32_t* padding)
+{
+    MOZ_ASSERT(UseHardFpABI());
+    MOZ_ASSERT(usedFloatArgs >= NumFloatArgRegs);
+    uint32_t intSlots = 0;
+    if (usedIntArgs > NumIntArgRegs)
+        intSlots = usedIntArgs - NumIntArgRegs;
+    uint32_t float32Slots = usedFloatArgs - NumFloatArgRegs;
+    return (intSlots + float32Slots + *padding) * sizeof(intptr_t);
+}
+
+static inline uint32_t
+GetDoubleArgStackDisp(uint32_t usedIntArgs, uint32_t usedFloatArgs, uint32_t* padding)
+{
+    MOZ_ASSERT(UseHardFpABI());
+    MOZ_ASSERT(usedFloatArgs >= NumFloatArgRegs);
+    uint32_t intSlots = 0;
+    if (usedIntArgs > NumIntArgRegs) {
+        intSlots = usedIntArgs - NumIntArgRegs;
+        // Update the amount of padding required.
+        *padding += (*padding + usedIntArgs) % 2;
+    }
+    uint32_t doubleSlots = usedFloatArgs - NumFloatArgRegs;
+    doubleSlots *= 2;
+    return (intSlots + doubleSlots + *padding) * sizeof(intptr_t);
+}
+
+#endif
+
+class DoubleEncoder
+{
+    struct DoubleEntry
+    {
+        uint32_t dblTop;
+        datastore::Imm8VFPImmData data;
+    };
+
+    static const DoubleEntry table[256];
+
+  public:
+    bool lookup(uint32_t top, datastore::Imm8VFPImmData* ret) const {
+        for (int i = 0; i < 256; i++) {
+            if (table[i].dblTop == top) {
+                *ret = table[i].data;
+                return true;
+            }
+        }
+        return false;
+    }
+};
+
+class AutoForbidPools
+{
+    Assembler* masm_;
+
+  public:
+    // The maxInst argument is the maximum number of word sized instructions
+    // that will be allocated within this context. It is used to determine if
+    // the pool needs to be dumped before entering this content. The debug code
+    // checks that no more than maxInst instructions are actually allocated.
+    //
+    // Allocation of pool entries is not supported within this content so the
+    // code can not use large integers or float constants etc.
+    AutoForbidPools(Assembler* masm, size_t maxInst)
+      : masm_(masm)
+    {
+        masm_->enterNoPool(maxInst);
+    }
+
+    ~AutoForbidPools() {
+        masm_->leaveNoPool();
+    }
+};
+
+} // namespace jit
+} // namespace js
+
+#endif /* jit_arm_Assembler_arm_h */
diff --git a/js/src/jit/arm/AtomicOperations-arm.h b/js/src/jit/arm/AtomicOperations-arm.h
new file mode 100644
index 0000000000..7e988ed29a
--- /dev/null
+++ b/js/src/jit/arm/AtomicOperations-arm.h
@@ -0,0 +1,247 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/* For documentation, see jit/AtomicOperations.h */
+
+#ifndef jit_arm_AtomicOperations_arm_h
+#define jit_arm_AtomicOperations_arm_h
+
+#include "jit/arm/Architecture-arm.h"
+
+#if defined(__clang__) || defined(__GNUC__)
+
+// The default implementation tactic for gcc/clang is to use the newer
+// __atomic intrinsics added for use in C++11 <atomic>.  Where that
+// isn't available, we use GCC's older __sync functions instead.
+//
+// ATOMICS_IMPLEMENTED_WITH_SYNC_INTRINSICS is kept as a backward
+// compatible option for older compilers: enable this to use GCC's old
+// __sync functions instead of the newer __atomic functions.  This
+// will be required for GCC 4.6.x and earlier, and probably for Clang
+// 3.1, should we need to use those versions.
+
+//#define ATOMICS_IMPLEMENTED_WITH_SYNC_INTRINSICS
+
+inline bool
+js::jit::AtomicOperations::isLockfree8()
+{
+    // The JIT and the C++ compiler must agree on whether to use atomics
+    // for 64-bit accesses.  There are two ways to do this: either the
+    // JIT defers to the C++ compiler (so if the C++ code is compiled
+    // for ARMv6, say, and __atomic_always_lock_free(8) is false, then the
+    // JIT ignores the fact that the program is running on ARMv7 or newer);
+    // or the C++ code in this file calls out to run-time generated code
+    // to do whatever the JIT does.
+    //
+    // For now, make the JIT defer to the C++ compiler when we know what
+    // the C++ compiler will do, otherwise assume a lock is needed.
+# ifndef ATOMICS_IMPLEMENTED_WITH_SYNC_INTRINSICS
+    MOZ_ASSERT(__atomic_always_lock_free(sizeof(int8_t), 0));
+    MOZ_ASSERT(__atomic_always_lock_free(sizeof(int16_t), 0));
+    MOZ_ASSERT(__atomic_always_lock_free(sizeof(int32_t), 0));
+    return HasLDSTREXBHD() && __atomic_always_lock_free(sizeof(int64_t), 0);
+# else
+    return false;
+# endif
+}
+
+inline void
+js::jit::AtomicOperations::fenceSeqCst()
+{
+# ifdef ATOMICS_IMPLEMENTED_WITH_SYNC_INTRINSICS
+    __sync_synchronize();
+# else
+    __atomic_thread_fence(__ATOMIC_SEQ_CST);
+# endif
+}
+
+template<typename T>
+inline T
+js::jit::AtomicOperations::loadSeqCst(T* addr)
+{
+    MOZ_ASSERT(sizeof(T) < 8 || isLockfree8());
+# ifdef ATOMICS_IMPLEMENTED_WITH_SYNC_INTRINSICS
+    __sync_synchronize();
+    T v = *addr;
+    __sync_synchronize();
+# else
+    T v;
+    __atomic_load(addr, &v, __ATOMIC_SEQ_CST);
+# endif
+    return v;
+}
+
+template<typename T>
+inline void
+js::jit::AtomicOperations::storeSeqCst(T* addr, T val)
+{
+    MOZ_ASSERT(sizeof(T) < 8 || isLockfree8());
+# ifdef ATOMICS_IMPLEMENTED_WITH_SYNC_INTRINSICS
+    __sync_synchronize();
+    *addr = val;
+    __sync_synchronize();
+# else
+    __atomic_store(addr, &val, __ATOMIC_SEQ_CST);
+# endif
+}
+
+template<typename T>
+inline T
+js::jit::AtomicOperations::exchangeSeqCst(T* addr, T val)
+{
+    MOZ_ASSERT(sizeof(T) < 8 || isLockfree8());
+# ifdef ATOMICS_IMPLEMENTED_WITH_SYNC_INTRINSICS
+    T v;
+    __sync_synchronize();
+    do {
+	v = *addr;
+    } while (__sync_val_compare_and_swap(addr, v, val) != v);
+    return v;
+# else
+    T v;
+    __atomic_exchange(addr, &val, &v, __ATOMIC_SEQ_CST);
+    return v;
+# endif
+}
+
+template<typename T>
+inline T
+js::jit::AtomicOperations::compareExchangeSeqCst(T* addr, T oldval, T newval)
+{
+    MOZ_ASSERT(sizeof(T) < 8 || isLockfree8());
+# ifdef ATOMICS_IMPLEMENTED_WITH_SYNC_INTRINSICS
+    return __sync_val_compare_and_swap(addr, oldval, newval);
+# else
+    __atomic_compare_exchange(addr, &oldval, &newval, false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST);
+    return oldval;
+# endif
+}
+
+template<typename T>
+inline T
+js::jit::AtomicOperations::fetchAddSeqCst(T* addr, T val)
+{
+    static_assert(sizeof(T) <= 4, "not available for 8-byte values yet");
+# ifdef ATOMICS_IMPLEMENTED_WITH_SYNC_INTRINSICS
+    return __sync_fetch_and_add(addr, val);
+# else
+    return __atomic_fetch_add(addr, val, __ATOMIC_SEQ_CST);
+# endif
+}
+
+template<typename T>
+inline T
+js::jit::AtomicOperations::fetchSubSeqCst(T* addr, T val)
+{
+    static_assert(sizeof(T) <= 4, "not available for 8-byte values yet");
+# ifdef ATOMICS_IMPLEMENTED_WITH_SYNC_INTRINSICS
+    return __sync_fetch_and_sub(addr, val);
+# else
+    return __atomic_fetch_sub(addr, val, __ATOMIC_SEQ_CST);
+# endif
+}
+
+template<typename T>
+inline T
+js::jit::AtomicOperations::fetchAndSeqCst(T* addr, T val)
+{
+    static_assert(sizeof(T) <= 4, "not available for 8-byte values yet");
+# ifdef ATOMICS_IMPLEMENTED_WITH_SYNC_INTRINSICS
+    return __sync_fetch_and_and(addr, val);
+# else
+    return __atomic_fetch_and(addr, val, __ATOMIC_SEQ_CST);
+# endif
+}
+
+template<typename T>
+inline T
+js::jit::AtomicOperations::fetchOrSeqCst(T* addr, T val)
+{
+    static_assert(sizeof(T) <= 4, "not available for 8-byte values yet");
+# ifdef ATOMICS_IMPLEMENTED_WITH_SYNC_INTRINSICS
+    return __sync_fetch_and_or(addr, val);
+# else
+    return __atomic_fetch_or(addr, val, __ATOMIC_SEQ_CST);
+# endif
+}
+
+template<typename T>
+inline T
+js::jit::AtomicOperations::fetchXorSeqCst(T* addr, T val)
+{
+    static_assert(sizeof(T) <= 4, "not available for 8-byte values yet");
+# ifdef ATOMICS_IMPLEMENTED_WITH_SYNC_INTRINSICS
+    return __sync_fetch_and_xor(addr, val);
+# else
+    return __atomic_fetch_xor(addr, val, __ATOMIC_SEQ_CST);
+# endif
+}
+
+template<typename T>
+inline T
+js::jit::AtomicOperations::loadSafeWhenRacy(T* addr)
+{
+    return *addr;               // FIXME (1208663): not yet safe
+}
+
+template<typename T>
+inline void
+js::jit::AtomicOperations::storeSafeWhenRacy(T* addr, T val)
+{
+    *addr = val;                // FIXME (1208663): not yet safe
+}
+
+inline void
+js::jit::AtomicOperations::memcpySafeWhenRacy(void* dest, const void* src, size_t nbytes)
+{
+    memcpy(dest, src, nbytes); // FIXME (1208663): not yet safe
+}
+
+inline void
+js::jit::AtomicOperations::memmoveSafeWhenRacy(void* dest, const void* src, size_t nbytes)
+{
+    memmove(dest, src, nbytes); // FIXME (1208663): not yet safe
+}
+
+template<size_t nbytes>
+inline void
+js::jit::RegionLock::acquire(void* addr)
+{
+# ifdef ATOMICS_IMPLEMENTED_WITH_SYNC_INTRINSICS
+    while (!__sync_bool_compare_and_swap(&spinlock, 0, 1))
+        ;
+# else
+    uint32_t zero = 0;
+    uint32_t one = 1;
+    while (!__atomic_compare_exchange(&spinlock, &zero, &one, false, __ATOMIC_ACQUIRE, __ATOMIC_ACQUIRE)) {
+        zero = 0;
+        continue;
+    }
+# endif
+}
+
+template<size_t nbytes>
+inline void
+js::jit::RegionLock::release(void* addr)
+{
+    MOZ_ASSERT(AtomicOperations::loadSeqCst(&spinlock) == 1, "releasing unlocked region lock");
+# ifdef ATOMICS_IMPLEMENTED_WITH_SYNC_INTRINSICS
+    __sync_sub_and_fetch(&spinlock, 1);
+# else
+    uint32_t zero = 0;
+    __atomic_store(&spinlock, &zero, __ATOMIC_SEQ_CST);
+# endif
+}
+
+# undef ATOMICS_IMPLEMENTED_WITH_SYNC_INTRINSICS
+
+#elif defined(ENABLE_SHARED_ARRAY_BUFFER)
+
+# error "Either disable JS shared memory at compile time, use GCC or Clang, or add code here"
+
+#endif
+
+#endif // jit_arm_AtomicOperations_arm_h
diff --git a/js/src/jit/arm/Bailouts-arm.cpp b/js/src/jit/arm/Bailouts-arm.cpp
new file mode 100644
index 0000000000..db7f69d582
--- /dev/null
+++ b/js/src/jit/arm/Bailouts-arm.cpp
@@ -0,0 +1,119 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "jscntxt.h"
+#include "jscompartment.h"
+
+#include "jit/arm/Assembler-arm.h"
+#include "jit/Bailouts.h"
+#include "jit/JitCompartment.h"
+
+using namespace js;
+using namespace js::jit;
+
+namespace js {
+namespace jit {
+
+class BailoutStack
+{
+    uintptr_t frameClassId_;
+    // This is pushed in the bailout handler. Both entry points into the handler
+    // inserts their own value int lr, which is then placed onto the stack along
+    // with frameClassId_ above. This should be migrated to ip.
+  public:
+    union {
+        uintptr_t frameSize_;
+        uintptr_t tableOffset_;
+    };
+
+  protected: // Silence Clang warning about unused private fields.
+    RegisterDump::FPUArray fpregs_;
+    RegisterDump::GPRArray regs_;
+
+    uintptr_t snapshotOffset_;
+    uintptr_t padding_;
+
+  public:
+    FrameSizeClass frameClass() const {
+        return FrameSizeClass::FromClass(frameClassId_);
+    }
+    uintptr_t tableOffset() const {
+        MOZ_ASSERT(frameClass() != FrameSizeClass::None());
+        return tableOffset_;
+    }
+    uint32_t frameSize() const {
+        if (frameClass() == FrameSizeClass::None())
+            return frameSize_;
+        return frameClass().frameSize();
+    }
+    MachineState machine() {
+        return MachineState::FromBailout(regs_, fpregs_);
+    }
+    SnapshotOffset snapshotOffset() const {
+        MOZ_ASSERT(frameClass() == FrameSizeClass::None());
+        return snapshotOffset_;
+    }
+    uint8_t* parentStackPointer() const {
+        if (frameClass() == FrameSizeClass::None())
+            return (uint8_t*)this + sizeof(BailoutStack);
+        return (uint8_t*)this + offsetof(BailoutStack, snapshotOffset_);
+    }
+};
+
+// Make sure the compiler doesn't add extra padding.
+static_assert((sizeof(BailoutStack) % 8) == 0, "BailoutStack should be 8-byte aligned.");
+
+} // namespace jit
+} // namespace js
+
+BailoutFrameInfo::BailoutFrameInfo(const JitActivationIterator& activations,
+                                   BailoutStack* bailout)
+  : machine_(bailout->machine())
+{
+    uint8_t* sp = bailout->parentStackPointer();
+    framePointer_ = sp + bailout->frameSize();
+    topFrameSize_ = framePointer_ - sp;
+
+    JSScript* script = ScriptFromCalleeToken(((JitFrameLayout*) framePointer_)->calleeToken());
+    JitActivation* activation = activations.activation()->asJit();
+    topIonScript_ = script->ionScript();
+
+    attachOnJitActivation(activations);
+
+    if (bailout->frameClass() == FrameSizeClass::None()) {
+        snapshotOffset_ = bailout->snapshotOffset();
+        return;
+    }
+
+    // Compute the snapshot offset from the bailout ID.
+    JSRuntime* rt = activation->compartment()->runtimeFromMainThread();
+    JitCode* code = rt->jitRuntime()->getBailoutTable(bailout->frameClass());
+    uintptr_t tableOffset = bailout->tableOffset();
+    uintptr_t tableStart = reinterpret_cast<uintptr_t>(Assembler::BailoutTableStart(code->raw()));
+
+    MOZ_ASSERT(tableOffset >= tableStart &&
+               tableOffset < tableStart + code->instructionsSize());
+    MOZ_ASSERT((tableOffset - tableStart) % BAILOUT_TABLE_ENTRY_SIZE == 0);
+
+    uint32_t bailoutId = ((tableOffset - tableStart) / BAILOUT_TABLE_ENTRY_SIZE) - 1;
+    MOZ_ASSERT(bailoutId < BAILOUT_TABLE_SIZE);
+
+    snapshotOffset_ = topIonScript_->bailoutToSnapshot(bailoutId);
+}
+
+BailoutFrameInfo::BailoutFrameInfo(const JitActivationIterator& activations,
+                                   InvalidationBailoutStack* bailout)
+  : machine_(bailout->machine())
+{
+    framePointer_ = (uint8_t*) bailout->fp();
+    topFrameSize_ = framePointer_ - bailout->sp();
+    topIonScript_ = bailout->ionScript();
+    attachOnJitActivation(activations);
+
+    uint8_t* returnAddressToFp_ = bailout->osiPointReturnAddress();
+    const OsiIndex* osiIndex = topIonScript_->getOsiIndex(returnAddressToFp_);
+    snapshotOffset_ = osiIndex->snapshotOffset();
+}
diff --git a/js/src/jit/arm/BaselineCompiler-arm.cpp b/js/src/jit/arm/BaselineCompiler-arm.cpp
new file mode 100644
index 0000000000..502a06e23c
--- /dev/null
+++ b/js/src/jit/arm/BaselineCompiler-arm.cpp
@@ -0,0 +1,15 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "jit/arm/BaselineCompiler-arm.h"
+
+using namespace js;
+using namespace js::jit;
+
+BaselineCompilerARM::BaselineCompilerARM(JSContext* cx, TempAllocator& alloc, JSScript* script)
+  : BaselineCompilerShared(cx, alloc, script)
+{
+}
diff --git a/js/src/jit/arm/BaselineCompiler-arm.h b/js/src/jit/arm/BaselineCompiler-arm.h
new file mode 100644
index 0000000000..1dcc337193
--- /dev/null
+++ b/js/src/jit/arm/BaselineCompiler-arm.h
@@ -0,0 +1,26 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef jit_arm_BaselineCompiler_arm_h
+#define jit_arm_BaselineCompiler_arm_h
+
+#include "jit/shared/BaselineCompiler-shared.h"
+
+namespace js {
+namespace jit {
+
+class BaselineCompilerARM : public BaselineCompilerShared
+{
+  protected:
+    BaselineCompilerARM(JSContext* cx, TempAllocator& alloc, JSScript* script);
+};
+
+typedef BaselineCompilerARM BaselineCompilerSpecific;
+
+} // namespace jit
+} // namespace js
+
+#endif /* jit_arm_BaselineCompiler_arm_h */
diff --git a/js/src/jit/arm/BaselineIC-arm.cpp b/js/src/jit/arm/BaselineIC-arm.cpp
new file mode 100644
index 0000000000..8534638882
--- /dev/null
+++ b/js/src/jit/arm/BaselineIC-arm.cpp
@@ -0,0 +1,74 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "jit/BaselineCompiler.h"
+#include "jit/BaselineIC.h"
+#include "jit/BaselineJIT.h"
+#include "jit/Linker.h"
+#include "jit/SharedICHelpers.h"
+
+#include "jit/MacroAssembler-inl.h"
+
+using namespace js;
+using namespace js::jit;
+
+namespace js {
+namespace jit {
+
+// ICCompare_Int32
+
+bool
+ICCompare_Int32::Compiler::generateStubCode(MacroAssembler& masm)
+{
+    // Guard that R0 is an integer and R1 is an integer.
+    Label failure;
+    masm.branchTestInt32(Assembler::NotEqual, R0, &failure);
+    masm.branchTestInt32(Assembler::NotEqual, R1, &failure);
+
+    // Compare payload regs of R0 and R1.
+    Assembler::Condition cond = JSOpToCondition(op, /* signed = */true);
+    masm.cmp32(R0.payloadReg(), R1.payloadReg());
+    masm.ma_mov(Imm32(1), R0.payloadReg(), cond);
+    masm.ma_mov(Imm32(0), R0.payloadReg(), Assembler::InvertCondition(cond));
+
+    // Result is implicitly boxed already.
+    masm.tagValue(JSVAL_TYPE_BOOLEAN, R0.payloadReg(), R0);
+    EmitReturnFromIC(masm);
+
+    // Failure case - jump to next stub.
+    masm.bind(&failure);
+    EmitStubGuardFailure(masm);
+
+    return true;
+}
+
+bool
+ICCompare_Double::Compiler::generateStubCode(MacroAssembler& masm)
+{
+    Label failure, isNaN;
+    masm.ensureDouble(R0, FloatReg0, &failure);
+    masm.ensureDouble(R1, FloatReg1, &failure);
+
+    Register dest = R0.scratchReg();
+
+    Assembler::DoubleCondition doubleCond = JSOpToDoubleCondition(op);
+    Assembler::Condition cond = Assembler::ConditionFromDoubleCondition(doubleCond);
+
+    masm.compareDouble(FloatReg0, FloatReg1);
+    masm.ma_mov(Imm32(0), dest);
+    masm.ma_mov(Imm32(1), dest, cond);
+
+    masm.tagValue(JSVAL_TYPE_BOOLEAN, dest, R0);
+    EmitReturnFromIC(masm);
+
+    // Failure case - jump to next stub.
+    masm.bind(&failure);
+    EmitStubGuardFailure(masm);
+    return true;
+}
+
+} // namespace jit
+} // namespace js
diff --git a/js/src/jit/arm/CodeGenerator-arm.cpp b/js/src/jit/arm/CodeGenerator-arm.cpp
new file mode 100644
index 0000000000..f8f77b7d51
--- /dev/null
+++ b/js/src/jit/arm/CodeGenerator-arm.cpp
@@ -0,0 +1,3720 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "jit/arm/CodeGenerator-arm.h"
+
+#include "mozilla/MathAlgorithms.h"
+
+#include "jscntxt.h"
+#include "jscompartment.h"
+#include "jsnum.h"
+
+#include "jit/CodeGenerator.h"
+#include "jit/JitCompartment.h"
+#include "jit/JitFrames.h"
+#include "jit/MIR.h"
+#include "jit/MIRGraph.h"
+#include "js/Conversions.h"
+#include "vm/Shape.h"
+#include "vm/TraceLogging.h"
+
+#include "jsscriptinlines.h"
+
+#include "jit/MacroAssembler-inl.h"
+#include "jit/shared/CodeGenerator-shared-inl.h"
+
+using namespace js;
+using namespace js::jit;
+
+using mozilla::FloorLog2;
+using mozilla::NegativeInfinity;
+using JS::GenericNaN;
+using JS::ToInt32;
+
+// shared
+CodeGeneratorARM::CodeGeneratorARM(MIRGenerator* gen, LIRGraph* graph, MacroAssembler* masm)
+  : CodeGeneratorShared(gen, graph, masm)
+{
+}
+
+Register64
+CodeGeneratorARM::ToOperandOrRegister64(const LInt64Allocation input)
+{
+    return ToRegister64(input);
+}
+
+void
+CodeGeneratorARM::emitBranch(Assembler::Condition cond, MBasicBlock* mirTrue, MBasicBlock* mirFalse)
+{
+    if (isNextBlock(mirFalse->lir())) {
+        jumpToBlock(mirTrue, cond);
+    } else {
+        jumpToBlock(mirFalse, Assembler::InvertCondition(cond));
+        jumpToBlock(mirTrue);
+    }
+}
+
+void
+OutOfLineBailout::accept(CodeGeneratorARM* codegen)
+{
+    codegen->visitOutOfLineBailout(this);
+}
+
+void
+CodeGeneratorARM::visitTestIAndBranch(LTestIAndBranch* test)
+{
+    const LAllocation* opd = test->getOperand(0);
+    MBasicBlock* ifTrue = test->ifTrue();
+    MBasicBlock* ifFalse = test->ifFalse();
+
+    // Test the operand
+    masm.as_cmp(ToRegister(opd), Imm8(0));
+
+    if (isNextBlock(ifFalse->lir())) {
+        jumpToBlock(ifTrue, Assembler::NonZero);
+    } else if (isNextBlock(ifTrue->lir())) {
+        jumpToBlock(ifFalse, Assembler::Zero);
+    } else {
+        jumpToBlock(ifFalse, Assembler::Zero);
+        jumpToBlock(ifTrue);
+    }
+}
+
+void
+CodeGeneratorARM::visitCompare(LCompare* comp)
+{
+    Assembler::Condition cond = JSOpToCondition(comp->mir()->compareType(), comp->jsop());
+    const LAllocation* left = comp->getOperand(0);
+    const LAllocation* right = comp->getOperand(1);
+    const LDefinition* def = comp->getDef(0);
+
+    ScratchRegisterScope scratch(masm);
+
+    if (right->isConstant()) {
+        masm.ma_cmp(ToRegister(left), Imm32(ToInt32(right)), scratch);
+    } else if (right->isRegister()) {
+        masm.ma_cmp(ToRegister(left), ToRegister(right));
+    } else {
+        SecondScratchRegisterScope scratch2(masm);
+        masm.ma_cmp(ToRegister(left), Operand(ToAddress(right)), scratch, scratch2);
+    }
+    masm.ma_mov(Imm32(0), ToRegister(def));
+    masm.ma_mov(Imm32(1), ToRegister(def), cond);
+}
+
+void
+CodeGeneratorARM::visitCompareAndBranch(LCompareAndBranch* comp)
+{
+    Assembler::Condition cond = JSOpToCondition(comp->cmpMir()->compareType(), comp->jsop());
+    const LAllocation* left = comp->left();
+    const LAllocation* right = comp->right();
+
+    ScratchRegisterScope scratch(masm);
+
+    if (right->isConstant()) {
+        masm.ma_cmp(ToRegister(left), Imm32(ToInt32(right)), scratch);
+    } else if (right->isRegister()) {
+        masm.ma_cmp(ToRegister(left), ToRegister(right));
+    } else {
+        SecondScratchRegisterScope scratch2(masm);
+        masm.ma_cmp(ToRegister(left), Operand(ToAddress(right)), scratch, scratch2);
+    }
+    emitBranch(cond, comp->ifTrue(), comp->ifFalse());
+}
+
+bool
+CodeGeneratorARM::generateOutOfLineCode()
+{
+    if (!CodeGeneratorShared::generateOutOfLineCode())
+        return false;
+
+    if (deoptLabel_.used()) {
+        // All non-table-based bailouts will go here.
+        masm.bind(&deoptLabel_);
+
+        // Push the frame size, so the handler can recover the IonScript.
+        masm.ma_mov(Imm32(frameSize()), lr);
+
+        JitCode* handler = gen->jitRuntime()->getGenericBailoutHandler();
+        masm.branch(handler);
+    }
+
+    return !masm.oom();
+}
+
+void
+CodeGeneratorARM::bailoutIf(Assembler::Condition condition, LSnapshot* snapshot)
+{
+    encode(snapshot);
+
+    // Though the assembler doesn't track all frame pushes, at least make sure
+    // the known value makes sense. We can't use bailout tables if the stack
+    // isn't properly aligned to the static frame size.
+    MOZ_ASSERT_IF(frameClass_ != FrameSizeClass::None(),
+                  frameClass_.frameSize() == masm.framePushed());
+
+    if (assignBailoutId(snapshot)) {
+        uint8_t* bailoutTable = Assembler::BailoutTableStart(deoptTable_->raw());
+        uint8_t* code = bailoutTable + snapshot->bailoutId() * BAILOUT_TABLE_ENTRY_SIZE;
+        masm.ma_b(code, condition);
+        return;
+    }
+
+    // We could not use a jump table, either because all bailout IDs were
+    // reserved, or a jump table is not optimal for this frame size or
+    // platform. Whatever, we will generate a lazy bailout.
+    InlineScriptTree* tree = snapshot->mir()->block()->trackedTree();
+    OutOfLineBailout* ool = new(alloc()) OutOfLineBailout(snapshot, masm.framePushed());
+
+    // All bailout code is associated with the bytecodeSite of the block we are
+    // bailing out from.
+    addOutOfLineCode(ool, new(alloc()) BytecodeSite(tree, tree->script()->code()));
+
+    masm.ma_b(ool->entry(), condition);
+}
+
+void
+CodeGeneratorARM::bailoutFrom(Label* label, LSnapshot* snapshot)
+{
+    if (masm.bailed())
+        return;
+
+    MOZ_ASSERT_IF(!masm.oom(), label->used());
+    MOZ_ASSERT_IF(!masm.oom(), !label->bound());
+
+    encode(snapshot);
+
+    // Though the assembler doesn't track all frame pushes, at least make sure
+    // the known value makes sense. We can't use bailout tables if the stack
+    // isn't properly aligned to the static frame size.
+    MOZ_ASSERT_IF(frameClass_ != FrameSizeClass::None(),
+                  frameClass_.frameSize() == masm.framePushed());
+
+    // On ARM we don't use a bailout table.
+    InlineScriptTree* tree = snapshot->mir()->block()->trackedTree();
+    OutOfLineBailout* ool = new(alloc()) OutOfLineBailout(snapshot, masm.framePushed());
+
+    // All bailout code is associated with the bytecodeSite of the block we are
+    // bailing out from.
+    addOutOfLineCode(ool, new(alloc()) BytecodeSite(tree, tree->script()->code()));
+
+    masm.retarget(label, ool->entry());
+}
+
+void
+CodeGeneratorARM::bailout(LSnapshot* snapshot)
+{
+    Label label;
+    masm.ma_b(&label);
+    bailoutFrom(&label, snapshot);
+}
+
+void
+CodeGeneratorARM::visitOutOfLineBailout(OutOfLineBailout* ool)
+{
+    ScratchRegisterScope scratch(masm);
+    masm.ma_mov(Imm32(ool->snapshot()->snapshotOffset()), scratch);
+    masm.ma_push(scratch); // BailoutStack::padding_
+    masm.ma_push(scratch); // BailoutStack::snapshotOffset_
+    masm.ma_b(&deoptLabel_);
+}
+
+void
+CodeGeneratorARM::visitMinMaxD(LMinMaxD* ins)
+{
+    FloatRegister first = ToFloatRegister(ins->first());
+    FloatRegister second = ToFloatRegister(ins->second());
+
+    MOZ_ASSERT(first == ToFloatRegister(ins->output()));
+
+    if (ins->mir()->isMax())
+        masm.maxDouble(second, first, true);
+    else
+        masm.minDouble(second, first, true);
+}
+
+void
+CodeGeneratorARM::visitMinMaxF(LMinMaxF* ins)
+{
+    FloatRegister first = ToFloatRegister(ins->first());
+    FloatRegister second = ToFloatRegister(ins->second());
+
+    MOZ_ASSERT(first == ToFloatRegister(ins->output()));
+
+    if (ins->mir()->isMax())
+        masm.maxFloat32(second, first, true);
+    else
+        masm.minFloat32(second, first, true);
+}
+
+void
+CodeGeneratorARM::visitAbsD(LAbsD* ins)
+{
+    FloatRegister input = ToFloatRegister(ins->input());
+    MOZ_ASSERT(input == ToFloatRegister(ins->output()));
+    masm.ma_vabs(input, input);
+}
+
+void
+CodeGeneratorARM::visitAbsF(LAbsF* ins)
+{
+    FloatRegister input = ToFloatRegister(ins->input());
+    MOZ_ASSERT(input == ToFloatRegister(ins->output()));
+    masm.ma_vabs_f32(input, input);
+}
+
+void
+CodeGeneratorARM::visitSqrtD(LSqrtD* ins)
+{
+    FloatRegister input = ToFloatRegister(ins->input());
+    FloatRegister output = ToFloatRegister(ins->output());
+    masm.ma_vsqrt(input, output);
+}
+
+void
+CodeGeneratorARM::visitSqrtF(LSqrtF* ins)
+{
+    FloatRegister input = ToFloatRegister(ins->input());
+    FloatRegister output = ToFloatRegister(ins->output());
+    masm.ma_vsqrt_f32(input, output);
+}
+
+void
+CodeGeneratorARM::visitAddI(LAddI* ins)
+{
+    const LAllocation* lhs = ins->getOperand(0);
+    const LAllocation* rhs = ins->getOperand(1);
+    const LDefinition* dest = ins->getDef(0);
+
+    ScratchRegisterScope scratch(masm);
+
+    if (rhs->isConstant())
+        masm.ma_add(ToRegister(lhs), Imm32(ToInt32(rhs)), ToRegister(dest), scratch, SetCC);
+    else if (rhs->isRegister())
+        masm.ma_add(ToRegister(lhs), ToRegister(rhs), ToRegister(dest), SetCC);
+    else
+        masm.ma_add(ToRegister(lhs), Operand(ToAddress(rhs)), ToRegister(dest), SetCC);
+
+    if (ins->snapshot())
+        bailoutIf(Assembler::Overflow, ins->snapshot());
+}
+
+void
+CodeGeneratorARM::visitAddI64(LAddI64* lir)
+{
+    const LInt64Allocation lhs = lir->getInt64Operand(LAddI64::Lhs);
+    const LInt64Allocation rhs = lir->getInt64Operand(LAddI64::Rhs);
+
+    MOZ_ASSERT(ToOutRegister64(lir) == ToRegister64(lhs));
+
+    if (IsConstant(rhs)) {
+        masm.add64(Imm64(ToInt64(rhs)), ToRegister64(lhs));
+        return;
+    }
+
+    masm.add64(ToOperandOrRegister64(rhs), ToRegister64(lhs));
+}
+
+void
+CodeGeneratorARM::visitSubI(LSubI* ins)
+{
+    const LAllocation* lhs = ins->getOperand(0);
+    const LAllocation* rhs = ins->getOperand(1);
+    const LDefinition* dest = ins->getDef(0);
+
+    ScratchRegisterScope scratch(masm);
+
+    if (rhs->isConstant())
+        masm.ma_sub(ToRegister(lhs), Imm32(ToInt32(rhs)), ToRegister(dest), scratch, SetCC);
+    else if (rhs->isRegister())
+        masm.ma_sub(ToRegister(lhs), ToRegister(rhs), ToRegister(dest), SetCC);
+    else
+        masm.ma_sub(ToRegister(lhs), Operand(ToAddress(rhs)), ToRegister(dest), SetCC);
+
+    if (ins->snapshot())
+        bailoutIf(Assembler::Overflow, ins->snapshot());
+}
+
+void
+CodeGeneratorARM::visitSubI64(LSubI64* lir)
+{
+    const LInt64Allocation lhs = lir->getInt64Operand(LSubI64::Lhs);
+    const LInt64Allocation rhs = lir->getInt64Operand(LSubI64::Rhs);
+
+    MOZ_ASSERT(ToOutRegister64(lir) == ToRegister64(lhs));
+
+    if (IsConstant(rhs)) {
+        masm.sub64(Imm64(ToInt64(rhs)), ToRegister64(lhs));
+        return;
+    }
+
+    masm.sub64(ToOperandOrRegister64(rhs), ToRegister64(lhs));
+}
+
+void
+CodeGeneratorARM::visitMulI(LMulI* ins)
+{
+    const LAllocation* lhs = ins->getOperand(0);
+    const LAllocation* rhs = ins->getOperand(1);
+    const LDefinition* dest = ins->getDef(0);
+    MMul* mul = ins->mir();
+    MOZ_ASSERT_IF(mul->mode() == MMul::Integer, !mul->canBeNegativeZero() && !mul->canOverflow());
+
+    if (rhs->isConstant()) {
+        // Bailout when this condition is met.
+        Assembler::Condition c = Assembler::Overflow;
+        // Bailout on -0.0
+        int32_t constant = ToInt32(rhs);
+        if (mul->canBeNegativeZero() && constant <= 0) {
+            Assembler::Condition bailoutCond = (constant == 0) ? Assembler::LessThan : Assembler::Equal;
+            masm.as_cmp(ToRegister(lhs), Imm8(0));
+            bailoutIf(bailoutCond, ins->snapshot());
+        }
+        // TODO: move these to ma_mul.
+        switch (constant) {
+          case -1:
+            masm.as_rsb(ToRegister(dest), ToRegister(lhs), Imm8(0), SetCC);
+            break;
+          case 0:
+            masm.ma_mov(Imm32(0), ToRegister(dest));
+            return; // Escape overflow check;
+          case 1:
+            // Nop
+            masm.ma_mov(ToRegister(lhs), ToRegister(dest));
+            return; // Escape overflow check;
+          case 2:
+            masm.ma_add(ToRegister(lhs), ToRegister(lhs), ToRegister(dest), SetCC);
+            // Overflow is handled later.
+            break;
+          default: {
+            bool handled = false;
+            if (constant > 0) {
+                // Try shift and add sequences for a positive constant.
+                if (!mul->canOverflow()) {
+                    // If it cannot overflow, we can do lots of optimizations.
+                    Register src = ToRegister(lhs);
+                    uint32_t shift = FloorLog2(constant);
+                    uint32_t rest = constant - (1 << shift);
+                    // See if the constant has one bit set, meaning it can be
+                    // encoded as a bitshift.
+                    if ((1 << shift) == constant) {
+                        masm.ma_lsl(Imm32(shift), src, ToRegister(dest));
+                        handled = true;
+                    } else {
+                        // If the constant cannot be encoded as (1 << C1), see
+                        // if it can be encoded as (1 << C1) | (1 << C2), which
+                        // can be computed using an add and a shift.
+                        uint32_t shift_rest = FloorLog2(rest);
+                        if ((1u << shift_rest) == rest) {
+                            masm.as_add(ToRegister(dest), src, lsl(src, shift-shift_rest));
+                            if (shift_rest != 0)
+                                masm.ma_lsl(Imm32(shift_rest), ToRegister(dest), ToRegister(dest));
+                            handled = true;
+                        }
+                    }
+                } else if (ToRegister(lhs) != ToRegister(dest)) {
+                    // To stay on the safe side, only optimize things that are a
+                    // power of 2.
+
+                    uint32_t shift = FloorLog2(constant);
+                    if ((1 << shift) == constant) {
+                        // dest = lhs * pow(2,shift)
+                        masm.ma_lsl(Imm32(shift), ToRegister(lhs), ToRegister(dest));
+                        // At runtime, check (lhs == dest >> shift), if this
+                        // does not hold, some bits were lost due to overflow,
+                        // and the computation should be resumed as a double.
+                        masm.as_cmp(ToRegister(lhs), asr(ToRegister(dest), shift));
+                        c = Assembler::NotEqual;
+                        handled = true;
+                    }
+                }
+            }
+
+            if (!handled) {
+                ScratchRegisterScope scratch(masm);
+                if (mul->canOverflow())
+                    c = masm.ma_check_mul(ToRegister(lhs), Imm32(ToInt32(rhs)), ToRegister(dest), scratch, c);
+                else
+                    masm.ma_mul(ToRegister(lhs), Imm32(ToInt32(rhs)), ToRegister(dest), scratch);
+            }
+          }
+        }
+        // Bailout on overflow.
+        if (mul->canOverflow())
+            bailoutIf(c, ins->snapshot());
+    } else {
+        Assembler::Condition c = Assembler::Overflow;
+
+        if (mul->canOverflow()) {
+            ScratchRegisterScope scratch(masm);
+            c = masm.ma_check_mul(ToRegister(lhs), ToRegister(rhs), ToRegister(dest), scratch, c);
+        } else {
+            masm.ma_mul(ToRegister(lhs), ToRegister(rhs), ToRegister(dest));
+        }
+
+        // Bailout on overflow.
+        if (mul->canOverflow())
+            bailoutIf(c, ins->snapshot());
+
+        if (mul->canBeNegativeZero()) {
+            Label done;
+            masm.as_cmp(ToRegister(dest), Imm8(0));
+            masm.ma_b(&done, Assembler::NotEqual);
+
+            // Result is -0 if lhs or rhs is negative.
+            masm.ma_cmn(ToRegister(lhs), ToRegister(rhs));
+            bailoutIf(Assembler::Signed, ins->snapshot());
+
+            masm.bind(&done);
+        }
+    }
+}
+
+void
+CodeGeneratorARM::visitMulI64(LMulI64* lir)
+{
+    const LInt64Allocation lhs = lir->getInt64Operand(LMulI64::Lhs);
+    const LInt64Allocation rhs = lir->getInt64Operand(LMulI64::Rhs);
+
+    MOZ_ASSERT(ToRegister64(lhs) == ToOutRegister64(lir));
+
+    if (IsConstant(rhs)) {
+        int64_t constant = ToInt64(rhs);
+        switch (constant) {
+          case -1:
+            masm.neg64(ToRegister64(lhs));
+            return;
+          case 0:
+            masm.xor64(ToRegister64(lhs), ToRegister64(lhs));
+            return;
+          case 1:
+            // nop
+            return;
+          case 2:
+            masm.add64(ToRegister64(lhs), ToRegister64(lhs));
+            return;
+          default:
+            if (constant > 0) {
+                // Use shift if constant is power of 2.
+                int32_t shift = mozilla::FloorLog2(constant);
+                if (int64_t(1) << shift == constant) {
+                    masm.lshift64(Imm32(shift), ToRegister64(lhs));
+                    return;
+                }
+            }
+            Register temp = ToTempRegisterOrInvalid(lir->temp());
+            masm.mul64(Imm64(constant), ToRegister64(lhs), temp);
+        }
+    } else {
+        Register temp = ToTempRegisterOrInvalid(lir->temp());
+        masm.mul64(ToOperandOrRegister64(rhs), ToRegister64(lhs), temp);
+    }
+}
+
+void
+CodeGeneratorARM::divICommon(MDiv* mir, Register lhs, Register rhs, Register output,
+                             LSnapshot* snapshot, Label& done)
+{
+    ScratchRegisterScope scratch(masm);
+
+    if (mir->canBeNegativeOverflow()) {
+        // Handle INT32_MIN / -1;
+        // The integer division will give INT32_MIN, but we want -(double)INT32_MIN.
+
+        // Sets EQ if lhs == INT32_MIN.
+        masm.ma_cmp(lhs, Imm32(INT32_MIN), scratch);
+        // If EQ (LHS == INT32_MIN), sets EQ if rhs == -1.
+        masm.ma_cmp(rhs, Imm32(-1), scratch, Assembler::Equal);
+        if (mir->canTruncateOverflow()) {
+            if (mir->trapOnError()) {
+                masm.ma_b(trap(mir, wasm::Trap::IntegerOverflow), Assembler::Equal);
+            } else {
+                // (-INT32_MIN)|0 = INT32_MIN
+                Label skip;
+                masm.ma_b(&skip, Assembler::NotEqual);
+                masm.ma_mov(Imm32(INT32_MIN), output);
+                masm.ma_b(&done);
+                masm.bind(&skip);
+            }
+        } else {
+            MOZ_ASSERT(mir->fallible());
+            bailoutIf(Assembler::Equal, snapshot);
+        }
+    }
+
+    // Handle divide by zero.
+    if (mir->canBeDivideByZero()) {
+        masm.as_cmp(rhs, Imm8(0));
+        if (mir->canTruncateInfinities()) {
+            if (mir->trapOnError()) {
+                masm.ma_b(trap(mir, wasm::Trap::IntegerDivideByZero), Assembler::Equal);
+            } else {
+                // Infinity|0 == 0
+                Label skip;
+                masm.ma_b(&skip, Assembler::NotEqual);
+                masm.ma_mov(Imm32(0), output);
+                masm.ma_b(&done);
+                masm.bind(&skip);
+            }
+        } else {
+            MOZ_ASSERT(mir->fallible());
+            bailoutIf(Assembler::Equal, snapshot);
+        }
+    }
+
+    // Handle negative 0.
+    if (!mir->canTruncateNegativeZero() && mir->canBeNegativeZero()) {
+        Label nonzero;
+        masm.as_cmp(lhs, Imm8(0));
+        masm.ma_b(&nonzero, Assembler::NotEqual);
+        masm.as_cmp(rhs, Imm8(0));
+        MOZ_ASSERT(mir->fallible());
+        bailoutIf(Assembler::LessThan, snapshot);
+        masm.bind(&nonzero);
+    }
+}
+
+void
+CodeGeneratorARM::visitDivI(LDivI* ins)
+{
+    Register lhs = ToRegister(ins->lhs());
+    Register rhs = ToRegister(ins->rhs());
+    Register temp = ToRegister(ins->getTemp(0));
+    Register output = ToRegister(ins->output());
+    MDiv* mir = ins->mir();
+
+    Label done;
+    divICommon(mir, lhs, rhs, output, ins->snapshot(), done);
+
+    if (mir->canTruncateRemainder()) {
+        masm.ma_sdiv(lhs, rhs, output);
+    } else {
+        {
+            ScratchRegisterScope scratch(masm);
+            masm.ma_sdiv(lhs, rhs, temp);
+            masm.ma_mul(temp, rhs, scratch);
+            masm.ma_cmp(lhs, scratch);
+        }
+        bailoutIf(Assembler::NotEqual, ins->snapshot());
+        masm.ma_mov(temp, output);
+    }
+
+    masm.bind(&done);
+}
+
+extern "C" {
+    extern MOZ_EXPORT int64_t __aeabi_idivmod(int,int);
+    extern MOZ_EXPORT int64_t __aeabi_uidivmod(int,int);
+}
+
+void
+CodeGeneratorARM::visitSoftDivI(LSoftDivI* ins)
+{
+    Register lhs = ToRegister(ins->lhs());
+    Register rhs = ToRegister(ins->rhs());
+    Register output = ToRegister(ins->output());
+    MDiv* mir = ins->mir();
+
+    Label done;
+    divICommon(mir, lhs, rhs, output, ins->snapshot(), done);
+
+    masm.setupAlignedABICall();
+    masm.passABIArg(lhs);
+    masm.passABIArg(rhs);
+    if (gen->compilingWasm())
+        masm.callWithABI(wasm::SymbolicAddress::aeabi_idivmod);
+    else
+        masm.callWithABI(JS_FUNC_TO_DATA_PTR(void*, __aeabi_idivmod));
+
+    // idivmod returns the quotient in r0, and the remainder in r1.
+    if (!mir->canTruncateRemainder()) {
+        MOZ_ASSERT(mir->fallible());
+        masm.as_cmp(r1, Imm8(0));
+        bailoutIf(Assembler::NonZero, ins->snapshot());
+    }
+
+    masm.bind(&done);
+}
+
+void
+CodeGeneratorARM::visitDivPowTwoI(LDivPowTwoI* ins)
+{
+    MDiv* mir = ins->mir();
+    Register lhs = ToRegister(ins->numerator());
+    Register output = ToRegister(ins->output());
+    int32_t shift = ins->shift();
+
+    if (shift == 0) {
+        masm.ma_mov(lhs, output);
+        return;
+    }
+
+    if (!mir->isTruncated()) {
+        // If the remainder is != 0, bailout since this must be a double.
+        {
+            // The bailout code also needs the scratch register.
+            // Here it is only used as a dummy target to set CC flags.
+            ScratchRegisterScope scratch(masm);
+            masm.as_mov(scratch, lsl(lhs, 32 - shift), SetCC);
+        }
+        bailoutIf(Assembler::NonZero, ins->snapshot());
+    }
+
+    if (!mir->canBeNegativeDividend()) {
+        // Numerator is unsigned, so needs no adjusting. Do the shift.
+        masm.as_mov(output, asr(lhs, shift));
+        return;
+    }
+
+    // Adjust the value so that shifting produces a correctly rounded result
+    // when the numerator is negative. See 10-1 "Signed Division by a Known
+    // Power of 2" in Henry S. Warren, Jr.'s Hacker's Delight.
+    ScratchRegisterScope scratch(masm);
+
+    if (shift > 1) {
+        masm.as_mov(scratch, asr(lhs, 31));
+        masm.as_add(scratch, lhs, lsr(scratch, 32 - shift));
+    } else {
+        masm.as_add(scratch, lhs, lsr(lhs, 32 - shift));
+    }
+
+    // Do the shift.
+    masm.as_mov(output, asr(scratch, shift));
+}
+
+void
+CodeGeneratorARM::modICommon(MMod* mir, Register lhs, Register rhs, Register output,
+                             LSnapshot* snapshot, Label& done)
+{
+    // 0/X (with X < 0) is bad because both of these values *should* be doubles,
+    // and the result should be -0.0, which cannot be represented in integers.
+    // X/0 is bad because it will give garbage (or abort), when it should give
+    // either \infty, -\infty or NaN.
+
+    // Prevent 0 / X (with X < 0) and X / 0
+    // testing X / Y. Compare Y with 0.
+    // There are three cases: (Y < 0), (Y == 0) and (Y > 0).
+    // If (Y < 0), then we compare X with 0, and bail if X == 0.
+    // If (Y == 0), then we simply want to bail. Since this does not set the
+    // flags necessary for LT to trigger, we don't test X, and take the bailout
+    // because the EQ flag is set.
+    // If (Y > 0), we don't set EQ, and we don't trigger LT, so we don't take
+    // the bailout.
+    if (mir->canBeDivideByZero() || mir->canBeNegativeDividend()) {
+        if (mir->trapOnError()) {
+            // wasm allows negative lhs and return 0 in this case.
+            MOZ_ASSERT(mir->isTruncated());
+            masm.as_cmp(rhs, Imm8(0));
+            masm.ma_b(trap(mir, wasm::Trap::IntegerDivideByZero), Assembler::Equal);
+            return;
+        }
+
+        masm.as_cmp(rhs, Imm8(0));
+        masm.as_cmp(lhs, Imm8(0), Assembler::LessThan);
+        if (mir->isTruncated()) {
+            // NaN|0 == 0 and (0 % -X)|0 == 0
+            Label skip;
+            masm.ma_b(&skip, Assembler::NotEqual);
+            masm.ma_mov(Imm32(0), output);
+            masm.ma_b(&done);
+            masm.bind(&skip);
+        } else {
+            MOZ_ASSERT(mir->fallible());
+            bailoutIf(Assembler::Equal, snapshot);
+        }
+    }
+}
+
+void
+CodeGeneratorARM::visitModI(LModI* ins)
+{
+    Register lhs = ToRegister(ins->lhs());
+    Register rhs = ToRegister(ins->rhs());
+    Register output = ToRegister(ins->output());
+    Register callTemp = ToRegister(ins->callTemp());
+    MMod* mir = ins->mir();
+
+    // Save the lhs in case we end up with a 0 that should be a -0.0 because lhs < 0.
+    masm.ma_mov(lhs, callTemp);
+
+    Label done;
+    modICommon(mir, lhs, rhs, output, ins->snapshot(), done);
+
+    {
+        ScratchRegisterScope scratch(masm);
+        masm.ma_smod(lhs, rhs, output, scratch);
+    }
+
+    // If X%Y == 0 and X < 0, then we *actually* wanted to return -0.0.
+    if (mir->canBeNegativeDividend()) {
+        if (mir->isTruncated()) {
+            // -0.0|0 == 0
+        } else {
+            MOZ_ASSERT(mir->fallible());
+            // See if X < 0
+            masm.as_cmp(output, Imm8(0));
+            masm.ma_b(&done, Assembler::NotEqual);
+            masm.as_cmp(callTemp, Imm8(0));
+            bailoutIf(Assembler::Signed, ins->snapshot());
+        }
+    }
+
+    masm.bind(&done);
+}
+
+void
+CodeGeneratorARM::visitSoftModI(LSoftModI* ins)
+{
+    // Extract the registers from this instruction.
+    Register lhs = ToRegister(ins->lhs());
+    Register rhs = ToRegister(ins->rhs());
+    Register output = ToRegister(ins->output());
+    Register callTemp = ToRegister(ins->callTemp());
+    MMod* mir = ins->mir();
+    Label done;
+
+    // Save the lhs in case we end up with a 0 that should be a -0.0 because lhs < 0.
+    MOZ_ASSERT(callTemp.code() > r3.code() && callTemp.code() < r12.code());
+    masm.ma_mov(lhs, callTemp);
+
+
+    // Prevent INT_MIN % -1;
+    // The integer division will give INT_MIN, but we want -(double)INT_MIN.
+    if (mir->canBeNegativeDividend()) {
+        {
+            ScratchRegisterScope scratch(masm);
+            // Sets EQ if lhs == INT_MIN
+            masm.ma_cmp(lhs, Imm32(INT_MIN), scratch);
+            // If EQ (LHS == INT_MIN), sets EQ if rhs == -1
+            masm.ma_cmp(rhs, Imm32(-1), scratch, Assembler::Equal);
+        }
+        if (mir->isTruncated()) {
+            // (INT_MIN % -1)|0 == 0
+            Label skip;
+            masm.ma_b(&skip, Assembler::NotEqual);
+            masm.ma_mov(Imm32(0), output);
+            masm.ma_b(&done);
+            masm.bind(&skip);
+        } else {
+            MOZ_ASSERT(mir->fallible());
+            bailoutIf(Assembler::Equal, ins->snapshot());
+        }
+    }
+
+    modICommon(mir, lhs, rhs, output, ins->snapshot(), done);
+
+    masm.setupAlignedABICall();
+    masm.passABIArg(lhs);
+    masm.passABIArg(rhs);
+    if (gen->compilingWasm())
+        masm.callWithABI(wasm::SymbolicAddress::aeabi_idivmod);
+    else
+        masm.callWithABI(JS_FUNC_TO_DATA_PTR(void*, __aeabi_idivmod));
+
+    // If X%Y == 0 and X < 0, then we *actually* wanted to return -0.0
+    if (mir->canBeNegativeDividend()) {
+        if (mir->isTruncated()) {
+            // -0.0|0 == 0
+        } else {
+            MOZ_ASSERT(mir->fallible());
+            // See if X < 0
+            masm.as_cmp(r1, Imm8(0));
+            masm.ma_b(&done, Assembler::NotEqual);
+            masm.as_cmp(callTemp, Imm8(0));
+            bailoutIf(Assembler::Signed, ins->snapshot());
+        }
+    }
+    masm.bind(&done);
+}
+
+void
+CodeGeneratorARM::visitModPowTwoI(LModPowTwoI* ins)
+{
+    Register in = ToRegister(ins->getOperand(0));
+    Register out = ToRegister(ins->getDef(0));
+    MMod* mir = ins->mir();
+    Label fin;
+    // bug 739870, jbramley has a different sequence that may help with speed
+    // here.
+
+    masm.ma_mov(in, out, SetCC);
+    masm.ma_b(&fin, Assembler::Zero);
+    masm.as_rsb(out, out, Imm8(0), LeaveCC, Assembler::Signed);
+    {
+        ScratchRegisterScope scratch(masm);
+        masm.ma_and(Imm32((1 << ins->shift()) - 1), out, scratch);
+    }
+    masm.as_rsb(out, out, Imm8(0), SetCC, Assembler::Signed);
+    if (mir->canBeNegativeDividend()) {
+        if (!mir->isTruncated()) {
+            MOZ_ASSERT(mir->fallible());
+            bailoutIf(Assembler::Zero, ins->snapshot());
+        } else {
+            // -0|0 == 0
+        }
+    }
+    masm.bind(&fin);
+}
+
+void
+CodeGeneratorARM::visitModMaskI(LModMaskI* ins)
+{
+    Register src = ToRegister(ins->getOperand(0));
+    Register dest = ToRegister(ins->getDef(0));
+    Register tmp1 = ToRegister(ins->getTemp(0));
+    Register tmp2 = ToRegister(ins->getTemp(1));
+    MMod* mir = ins->mir();
+
+    ScratchRegisterScope scratch(masm);
+    SecondScratchRegisterScope scratch2(masm);
+
+    masm.ma_mod_mask(src, dest, tmp1, tmp2, scratch, scratch2, ins->shift());
+
+    if (mir->canBeNegativeDividend()) {
+        if (!mir->isTruncated()) {
+            MOZ_ASSERT(mir->fallible());
+            bailoutIf(Assembler::Zero, ins->snapshot());
+        } else {
+            // -0|0 == 0
+        }
+    }
+}
+
+void
+CodeGeneratorARM::visitBitNotI(LBitNotI* ins)
+{
+    const LAllocation* input = ins->getOperand(0);
+    const LDefinition* dest = ins->getDef(0);
+    // This will not actually be true on arm. We can not an imm8m in order to
+    // get a wider range of numbers
+    MOZ_ASSERT(!input->isConstant());
+
+    masm.ma_mvn(ToRegister(input), ToRegister(dest));
+}
+
+void
+CodeGeneratorARM::visitBitOpI(LBitOpI* ins)
+{
+    const LAllocation* lhs = ins->getOperand(0);
+    const LAllocation* rhs = ins->getOperand(1);
+    const LDefinition* dest = ins->getDef(0);
+
+    ScratchRegisterScope scratch(masm);
+
+    // All of these bitops should be either imm32's, or integer registers.
+    switch (ins->bitop()) {
+      case JSOP_BITOR:
+        if (rhs->isConstant())
+            masm.ma_orr(Imm32(ToInt32(rhs)), ToRegister(lhs), ToRegister(dest), scratch);
+        else
+            masm.ma_orr(ToRegister(rhs), ToRegister(lhs), ToRegister(dest));
+        break;
+      case JSOP_BITXOR:
+        if (rhs->isConstant())
+            masm.ma_eor(Imm32(ToInt32(rhs)), ToRegister(lhs), ToRegister(dest), scratch);
+        else
+            masm.ma_eor(ToRegister(rhs), ToRegister(lhs), ToRegister(dest));
+        break;
+      case JSOP_BITAND:
+        if (rhs->isConstant())
+            masm.ma_and(Imm32(ToInt32(rhs)), ToRegister(lhs), ToRegister(dest), scratch);
+        else
+            masm.ma_and(ToRegister(rhs), ToRegister(lhs), ToRegister(dest));
+        break;
+      default:
+        MOZ_CRASH("unexpected binary opcode");
+    }
+}
+
+void
+CodeGeneratorARM::visitShiftI(LShiftI* ins)
+{
+    Register lhs = ToRegister(ins->lhs());
+    const LAllocation* rhs = ins->rhs();
+    Register dest = ToRegister(ins->output());
+
+    if (rhs->isConstant()) {
+        int32_t shift = ToInt32(rhs) & 0x1F;
+        switch (ins->bitop()) {
+          case JSOP_LSH:
+            if (shift)
+                masm.ma_lsl(Imm32(shift), lhs, dest);
+            else
+                masm.ma_mov(lhs, dest);
+            break;
+          case JSOP_RSH:
+            if (shift)
+                masm.ma_asr(Imm32(shift), lhs, dest);
+            else
+                masm.ma_mov(lhs, dest);
+            break;
+          case JSOP_URSH:
+            if (shift) {
+                masm.ma_lsr(Imm32(shift), lhs, dest);
+            } else {
+                // x >>> 0 can overflow.
+                masm.ma_mov(lhs, dest);
+                if (ins->mir()->toUrsh()->fallible()) {
+                    masm.as_cmp(dest, Imm8(0));
+                    bailoutIf(Assembler::LessThan, ins->snapshot());
+                }
+            }
+            break;
+          default:
+            MOZ_CRASH("Unexpected shift op");
+        }
+    } else {
+        // The shift amounts should be AND'ed into the 0-31 range since arm
+        // shifts by the lower byte of the register (it will attempt to shift by
+        // 250 if you ask it to).
+        masm.as_and(dest, ToRegister(rhs), Imm8(0x1F));
+
+        switch (ins->bitop()) {
+          case JSOP_LSH:
+            masm.ma_lsl(dest, lhs, dest);
+            break;
+          case JSOP_RSH:
+            masm.ma_asr(dest, lhs, dest);
+            break;
+          case JSOP_URSH:
+            masm.ma_lsr(dest, lhs, dest);
+            if (ins->mir()->toUrsh()->fallible()) {
+                // x >>> 0 can overflow.
+                masm.as_cmp(dest, Imm8(0));
+                bailoutIf(Assembler::LessThan, ins->snapshot());
+            }
+            break;
+          default:
+            MOZ_CRASH("Unexpected shift op");
+        }
+    }
+}
+
+void
+CodeGeneratorARM::visitUrshD(LUrshD* ins)
+{
+    Register lhs = ToRegister(ins->lhs());
+    Register temp = ToRegister(ins->temp());
+
+    const LAllocation* rhs = ins->rhs();
+    FloatRegister out = ToFloatRegister(ins->output());
+
+    if (rhs->isConstant()) {
+        int32_t shift = ToInt32(rhs) & 0x1F;
+        if (shift)
+            masm.ma_lsr(Imm32(shift), lhs, temp);
+        else
+            masm.ma_mov(lhs, temp);
+    } else {
+        masm.as_and(temp, ToRegister(rhs), Imm8(0x1F));
+        masm.ma_lsr(temp, lhs, temp);
+    }
+
+    masm.convertUInt32ToDouble(temp, out);
+}
+
+void
+CodeGeneratorARM::visitClzI(LClzI* ins)
+{
+    Register input = ToRegister(ins->input());
+    Register output = ToRegister(ins->output());
+
+    masm.clz32(input, output, /* knownNotZero = */ false);
+}
+
+void
+CodeGeneratorARM::visitCtzI(LCtzI* ins)
+{
+    Register input = ToRegister(ins->input());
+    Register output = ToRegister(ins->output());
+
+    masm.ctz32(input, output, /* knownNotZero = */ false);
+}
+
+void
+CodeGeneratorARM::visitPopcntI(LPopcntI* ins)
+{
+    Register input = ToRegister(ins->input());
+    Register output = ToRegister(ins->output());
+
+    Register tmp = ToRegister(ins->temp());
+
+    masm.popcnt32(input, output, tmp);
+}
+
+void
+CodeGeneratorARM::visitPowHalfD(LPowHalfD* ins)
+{
+    FloatRegister input = ToFloatRegister(ins->input());
+    FloatRegister output = ToFloatRegister(ins->output());
+    ScratchDoubleScope scratch(masm);
+
+    Label done;
+
+    // Masm.pow(-Infinity, 0.5) == Infinity.
+    masm.loadConstantDouble(NegativeInfinity<double>(), scratch);
+    masm.compareDouble(input, scratch);
+    masm.ma_vneg(scratch, output, Assembler::Equal);
+    masm.ma_b(&done, Assembler::Equal);
+
+    // Math.pow(-0, 0.5) == 0 == Math.pow(0, 0.5).
+    // Adding 0 converts any -0 to 0.
+    masm.loadConstantDouble(0.0, scratch);
+    masm.ma_vadd(scratch, input, output);
+    masm.ma_vsqrt(output, output);
+
+    masm.bind(&done);
+}
+
+MoveOperand
+CodeGeneratorARM::toMoveOperand(LAllocation a) const
+{
+    if (a.isGeneralReg())
+        return MoveOperand(ToRegister(a));
+    if (a.isFloatReg())
+        return MoveOperand(ToFloatRegister(a));
+    int32_t offset = ToStackOffset(a);
+    MOZ_ASSERT((offset & 3) == 0);
+    return MoveOperand(StackPointer, offset);
+}
+
+class js::jit::OutOfLineTableSwitch : public OutOfLineCodeBase<CodeGeneratorARM>
+{
+    MTableSwitch* mir_;
+    Vector<CodeLabel, 8, JitAllocPolicy> codeLabels_;
+
+    void accept(CodeGeneratorARM* codegen) {
+        codegen->visitOutOfLineTableSwitch(this);
+    }
+
+  public:
+    OutOfLineTableSwitch(TempAllocator& alloc, MTableSwitch* mir)
+      : mir_(mir),
+        codeLabels_(alloc)
+    {}
+
+    MTableSwitch* mir() const {
+        return mir_;
+    }
+
+    bool addCodeLabel(CodeLabel label) {
+        return codeLabels_.append(label);
+    }
+    CodeLabel codeLabel(unsigned i) {
+        return codeLabels_[i];
+    }
+};
+
+void
+CodeGeneratorARM::visitOutOfLineTableSwitch(OutOfLineTableSwitch* ool)
+{
+    MTableSwitch* mir = ool->mir();
+
+    size_t numCases = mir->numCases();
+    for (size_t i = 0; i < numCases; i++) {
+        LBlock* caseblock = skipTrivialBlocks(mir->getCase(numCases - 1 - i))->lir();
+        Label* caseheader = caseblock->label();
+        uint32_t caseoffset = caseheader->offset();
+
+        // The entries of the jump table need to be absolute addresses and thus
+        // must be patched after codegen is finished.
+        CodeLabel cl = ool->codeLabel(i);
+        cl.target()->bind(caseoffset);
+        masm.addCodeLabel(cl);
+    }
+}
+
+void
+CodeGeneratorARM::emitTableSwitchDispatch(MTableSwitch* mir, Register index, Register base)
+{
+    // The code generated by this is utter hax.
+    // The end result looks something like:
+    // SUBS index, input, #base
+    // RSBSPL index, index, #max
+    // LDRPL pc, pc, index lsl 2
+    // B default
+
+    // If the range of targets in N through M, we first subtract off the lowest
+    // case (N), which both shifts the arguments into the range 0 to (M - N)
+    // with and sets the MInus flag if the argument was out of range on the low
+    // end.
+
+    // Then we a reverse subtract with the size of the jump table, which will
+    // reverse the order of range (It is size through 0, rather than 0 through
+    // size). The main purpose of this is that we set the same flag as the lower
+    // bound check for the upper bound check. Lastly, we do this conditionally
+    // on the previous check succeeding.
+
+    // Then we conditionally load the pc offset by the (reversed) index (times
+    // the address size) into the pc, which branches to the correct case. NOTE:
+    // when we go to read the pc, the value that we get back is the pc of the
+    // current instruction *PLUS 8*. This means that ldr foo, [pc, +0] reads
+    // $pc+8. In other words, there is an empty word after the branch into the
+    // switch table before the table actually starts. Since the only other
+    // unhandled case is the default case (both out of range high and out of
+    // range low) I then insert a branch to default case into the extra slot,
+    // which ensures we don't attempt to execute the address table.
+    Label* defaultcase = skipTrivialBlocks(mir->getDefault())->lir()->label();
+
+    ScratchRegisterScope scratch(masm);
+
+    int32_t cases = mir->numCases();
+    // Lower value with low value.
+    masm.ma_sub(index, Imm32(mir->low()), index, scratch, SetCC);
+    masm.ma_rsb(index, Imm32(cases - 1), index, scratch, SetCC, Assembler::NotSigned);
+    // Inhibit pools within the following sequence because we are indexing into
+    // a pc relative table. The region will have one instruction for ma_ldr, one
+    // for ma_b, and each table case takes one word.
+    AutoForbidPools afp(&masm, 1 + 1 + cases);
+    masm.ma_ldr(DTRAddr(pc, DtrRegImmShift(index, LSL, 2)), pc, Offset, Assembler::NotSigned);
+    masm.ma_b(defaultcase);
+
+    // To fill in the CodeLabels for the case entries, we need to first generate
+    // the case entries (we don't yet know their offsets in the instruction
+    // stream).
+    OutOfLineTableSwitch* ool = new(alloc()) OutOfLineTableSwitch(alloc(), mir);
+    for (int32_t i = 0; i < cases; i++) {
+        CodeLabel cl;
+        masm.writeCodePointer(cl.patchAt());
+        masm.propagateOOM(ool->addCodeLabel(cl));
+    }
+    addOutOfLineCode(ool, mir);
+}
+
+void
+CodeGeneratorARM::visitMathD(LMathD* math)
+{
+    FloatRegister src1 = ToFloatRegister(math->getOperand(0));
+    FloatRegister src2 = ToFloatRegister(math->getOperand(1));
+    FloatRegister output = ToFloatRegister(math->getDef(0));
+
+    switch (math->jsop()) {
+      case JSOP_ADD:
+        masm.ma_vadd(src1, src2, output);
+        break;
+      case JSOP_SUB:
+        masm.ma_vsub(src1, src2, output);
+        break;
+      case JSOP_MUL:
+        masm.ma_vmul(src1, src2, output);
+        break;
+      case JSOP_DIV:
+        masm.ma_vdiv(src1, src2, output);
+        break;
+      default:
+        MOZ_CRASH("unexpected opcode");
+    }
+}
+
+void
+CodeGeneratorARM::visitMathF(LMathF* math)
+{
+    FloatRegister src1 = ToFloatRegister(math->getOperand(0));
+    FloatRegister src2 = ToFloatRegister(math->getOperand(1));
+    FloatRegister output = ToFloatRegister(math->getDef(0));
+
+    switch (math->jsop()) {
+      case JSOP_ADD:
+        masm.ma_vadd_f32(src1, src2, output);
+        break;
+      case JSOP_SUB:
+        masm.ma_vsub_f32(src1, src2, output);
+        break;
+      case JSOP_MUL:
+        masm.ma_vmul_f32(src1, src2, output);
+        break;
+      case JSOP_DIV:
+        masm.ma_vdiv_f32(src1, src2, output);
+        break;
+      default:
+        MOZ_CRASH("unexpected opcode");
+    }
+}
+
+void
+CodeGeneratorARM::visitFloor(LFloor* lir)
+{
+    FloatRegister input = ToFloatRegister(lir->input());
+    Register output = ToRegister(lir->output());
+    Label bail;
+    masm.floor(input, output, &bail);
+    bailoutFrom(&bail, lir->snapshot());
+}
+
+void
+CodeGeneratorARM::visitFloorF(LFloorF* lir)
+{
+    FloatRegister input = ToFloatRegister(lir->input());
+    Register output = ToRegister(lir->output());
+    Label bail;
+    masm.floorf(input, output, &bail);
+    bailoutFrom(&bail, lir->snapshot());
+}
+
+void
+CodeGeneratorARM::visitCeil(LCeil* lir)
+{
+    FloatRegister input = ToFloatRegister(lir->input());
+    Register output = ToRegister(lir->output());
+    Label bail;
+    masm.ceil(input, output, &bail);
+    bailoutFrom(&bail, lir->snapshot());
+}
+
+void
+CodeGeneratorARM::visitCeilF(LCeilF* lir)
+{
+    FloatRegister input = ToFloatRegister(lir->input());
+    Register output = ToRegister(lir->output());
+    Label bail;
+    masm.ceilf(input, output, &bail);
+    bailoutFrom(&bail, lir->snapshot());
+}
+
+void
+CodeGeneratorARM::visitRound(LRound* lir)
+{
+    FloatRegister input = ToFloatRegister(lir->input());
+    Register output = ToRegister(lir->output());
+    FloatRegister tmp = ToFloatRegister(lir->temp());
+    Label bail;
+    // Output is either correct, or clamped. All -0 cases have been translated
+    // to a clamped case.
+    masm.round(input, output, &bail, tmp);
+    bailoutFrom(&bail, lir->snapshot());
+}
+
+void
+CodeGeneratorARM::visitRoundF(LRoundF* lir)
+{
+    FloatRegister input = ToFloatRegister(lir->input());
+    Register output = ToRegister(lir->output());
+    FloatRegister tmp = ToFloatRegister(lir->temp());
+    Label bail;
+    // Output is either correct, or clamped. All -0 cases have been translated
+    // to a clamped case.
+    masm.roundf(input, output, &bail, tmp);
+    bailoutFrom(&bail, lir->snapshot());
+}
+
+void
+CodeGeneratorARM::emitRoundDouble(FloatRegister src, Register dest, Label* fail)
+{
+    ScratchDoubleScope scratch(masm);
+    ScratchRegisterScope scratchReg(masm);
+
+    masm.ma_vcvt_F64_I32(src, scratch);
+    masm.ma_vxfer(scratch, dest);
+    masm.ma_cmp(dest, Imm32(0x7fffffff), scratchReg);
+    masm.ma_cmp(dest, Imm32(0x80000000), scratchReg, Assembler::NotEqual);
+    masm.ma_b(fail, Assembler::Equal);
+}
+
+void
+CodeGeneratorARM::visitTruncateDToInt32(LTruncateDToInt32* ins)
+{
+    emitTruncateDouble(ToFloatRegister(ins->input()), ToRegister(ins->output()), ins->mir());
+}
+
+void
+CodeGeneratorARM::visitTruncateFToInt32(LTruncateFToInt32* ins)
+{
+    emitTruncateFloat32(ToFloatRegister(ins->input()), ToRegister(ins->output()), ins->mir());
+}
+
+static const uint32_t FrameSizes[] = { 128, 256, 512, 1024 };
+
+FrameSizeClass
+FrameSizeClass::FromDepth(uint32_t frameDepth)
+{
+    for (uint32_t i = 0; i < JS_ARRAY_LENGTH(FrameSizes); i++) {
+        if (frameDepth < FrameSizes[i])
+            return FrameSizeClass(i);
+    }
+
+    return FrameSizeClass::None();
+}
+
+FrameSizeClass
+FrameSizeClass::ClassLimit()
+{
+    return FrameSizeClass(JS_ARRAY_LENGTH(FrameSizes));
+}
+
+uint32_t
+FrameSizeClass::frameSize() const
+{
+    MOZ_ASSERT(class_ != NO_FRAME_SIZE_CLASS_ID);
+    MOZ_ASSERT(class_ < JS_ARRAY_LENGTH(FrameSizes));
+
+    return FrameSizes[class_];
+}
+
+ValueOperand
+CodeGeneratorARM::ToValue(LInstruction* ins, size_t pos)
+{
+    Register typeReg = ToRegister(ins->getOperand(pos + TYPE_INDEX));
+    Register payloadReg = ToRegister(ins->getOperand(pos + PAYLOAD_INDEX));
+    return ValueOperand(typeReg, payloadReg);
+}
+
+ValueOperand
+CodeGeneratorARM::ToOutValue(LInstruction* ins)
+{
+    Register typeReg = ToRegister(ins->getDef(TYPE_INDEX));
+    Register payloadReg = ToRegister(ins->getDef(PAYLOAD_INDEX));
+    return ValueOperand(typeReg, payloadReg);
+}
+
+ValueOperand
+CodeGeneratorARM::ToTempValue(LInstruction* ins, size_t pos)
+{
+    Register typeReg = ToRegister(ins->getTemp(pos + TYPE_INDEX));
+    Register payloadReg = ToRegister(ins->getTemp(pos + PAYLOAD_INDEX));
+    return ValueOperand(typeReg, payloadReg);
+}
+
+void
+CodeGeneratorARM::visitValue(LValue* value)
+{
+    const ValueOperand out = ToOutValue(value);
+
+    masm.moveValue(value->value(), out);
+}
+
+void
+CodeGeneratorARM::visitBox(LBox* box)
+{
+    const LDefinition* type = box->getDef(TYPE_INDEX);
+
+    MOZ_ASSERT(!box->getOperand(0)->isConstant());
+
+    // On x86, the input operand and the output payload have the same virtual
+    // register. All that needs to be written is the type tag for the type
+    // definition.
+    masm.ma_mov(Imm32(MIRTypeToTag(box->type())), ToRegister(type));
+}
+
+void
+CodeGeneratorARM::visitBoxFloatingPoint(LBoxFloatingPoint* box)
+{
+    const LDefinition* payload = box->getDef(PAYLOAD_INDEX);
+    const LDefinition* type = box->getDef(TYPE_INDEX);
+    const LAllocation* in = box->getOperand(0);
+    FloatRegister reg = ToFloatRegister(in);
+
+    if (box->type() == MIRType::Float32) {
+        ScratchFloat32Scope scratch(masm);
+        masm.convertFloat32ToDouble(reg, scratch);
+        masm.ma_vxfer(VFPRegister(scratch), ToRegister(payload), ToRegister(type));
+    } else {
+        masm.ma_vxfer(VFPRegister(reg), ToRegister(payload), ToRegister(type));
+    }
+}
+
+void
+CodeGeneratorARM::visitUnbox(LUnbox* unbox)
+{
+    // Note that for unbox, the type and payload indexes are switched on the
+    // inputs.
+    MUnbox* mir = unbox->mir();
+    Register type = ToRegister(unbox->type());
+
+    ScratchRegisterScope scratch(masm);
+
+    if (mir->fallible()) {
+        masm.ma_cmp(type, Imm32(MIRTypeToTag(mir->type())), scratch);
+        bailoutIf(Assembler::NotEqual, unbox->snapshot());
+    }
+}
+
+void
+CodeGeneratorARM::visitDouble(LDouble* ins)
+{
+    const LDefinition* out = ins->getDef(0);
+    masm.loadConstantDouble(ins->getDouble(), ToFloatRegister(out));
+}
+
+void
+CodeGeneratorARM::visitFloat32(LFloat32* ins)
+{
+    const LDefinition* out = ins->getDef(0);
+    masm.loadConstantFloat32(ins->getFloat(), ToFloatRegister(out));
+}
+
+Register
+CodeGeneratorARM::splitTagForTest(const ValueOperand& value)
+{
+    return value.typeReg();
+}
+
+void
+CodeGeneratorARM::visitTestDAndBranch(LTestDAndBranch* test)
+{
+    const LAllocation* opd = test->input();
+    masm.ma_vcmpz(ToFloatRegister(opd));
+    masm.as_vmrs(pc);
+
+    MBasicBlock* ifTrue = test->ifTrue();
+    MBasicBlock* ifFalse = test->ifFalse();
+    // If the compare set the 0 bit, then the result is definately false.
+    jumpToBlock(ifFalse, Assembler::Zero);
+    // It is also false if one of the operands is NAN, which is shown as
+    // Overflow.
+    jumpToBlock(ifFalse, Assembler::Overflow);
+    jumpToBlock(ifTrue);
+}
+
+void
+CodeGeneratorARM::visitTestFAndBranch(LTestFAndBranch* test)
+{
+    const LAllocation* opd = test->input();
+    masm.ma_vcmpz_f32(ToFloatRegister(opd));
+    masm.as_vmrs(pc);
+
+    MBasicBlock* ifTrue = test->ifTrue();
+    MBasicBlock* ifFalse = test->ifFalse();
+    // If the compare set the 0 bit, then the result is definately false.
+    jumpToBlock(ifFalse, Assembler::Zero);
+    // It is also false if one of the operands is NAN, which is shown as
+    // Overflow.
+    jumpToBlock(ifFalse, Assembler::Overflow);
+    jumpToBlock(ifTrue);
+}
+
+void
+CodeGeneratorARM::visitCompareD(LCompareD* comp)
+{
+    FloatRegister lhs = ToFloatRegister(comp->left());
+    FloatRegister rhs = ToFloatRegister(comp->right());
+
+    Assembler::DoubleCondition cond = JSOpToDoubleCondition(comp->mir()->jsop());
+    masm.compareDouble(lhs, rhs);
+    masm.emitSet(Assembler::ConditionFromDoubleCondition(cond), ToRegister(comp->output()));
+}
+
+void
+CodeGeneratorARM::visitCompareF(LCompareF* comp)
+{
+    FloatRegister lhs = ToFloatRegister(comp->left());
+    FloatRegister rhs = ToFloatRegister(comp->right());
+
+    Assembler::DoubleCondition cond = JSOpToDoubleCondition(comp->mir()->jsop());
+    masm.compareFloat(lhs, rhs);
+    masm.emitSet(Assembler::ConditionFromDoubleCondition(cond), ToRegister(comp->output()));
+}
+
+void
+CodeGeneratorARM::visitCompareDAndBranch(LCompareDAndBranch* comp)
+{
+    FloatRegister lhs = ToFloatRegister(comp->left());
+    FloatRegister rhs = ToFloatRegister(comp->right());
+
+    Assembler::DoubleCondition cond = JSOpToDoubleCondition(comp->cmpMir()->jsop());
+    masm.compareDouble(lhs, rhs);
+    emitBranch(Assembler::ConditionFromDoubleCondition(cond), comp->ifTrue(), comp->ifFalse());
+}
+
+void
+CodeGeneratorARM::visitCompareFAndBranch(LCompareFAndBranch* comp)
+{
+    FloatRegister lhs = ToFloatRegister(comp->left());
+    FloatRegister rhs = ToFloatRegister(comp->right());
+
+    Assembler::DoubleCondition cond = JSOpToDoubleCondition(comp->cmpMir()->jsop());
+    masm.compareFloat(lhs, rhs);
+    emitBranch(Assembler::ConditionFromDoubleCondition(cond), comp->ifTrue(), comp->ifFalse());
+}
+
+void
+CodeGeneratorARM::visitCompareB(LCompareB* lir)
+{
+    MCompare* mir = lir->mir();
+
+    const ValueOperand lhs = ToValue(lir, LCompareB::Lhs);
+    const LAllocation* rhs = lir->rhs();
+    const Register output = ToRegister(lir->output());
+
+    MOZ_ASSERT(mir->jsop() == JSOP_STRICTEQ || mir->jsop() == JSOP_STRICTNE);
+
+    Label notBoolean, done;
+    masm.branchTestBoolean(Assembler::NotEqual, lhs, &notBoolean);
+    {
+        if (rhs->isConstant())
+            masm.cmp32(lhs.payloadReg(), Imm32(rhs->toConstant()->toBoolean()));
+        else
+            masm.cmp32(lhs.payloadReg(), ToRegister(rhs));
+        masm.emitSet(JSOpToCondition(mir->compareType(), mir->jsop()), output);
+        masm.jump(&done);
+    }
+
+    masm.bind(&notBoolean);
+    {
+        masm.move32(Imm32(mir->jsop() == JSOP_STRICTNE), output);
+    }
+
+    masm.bind(&done);
+}
+
+void
+CodeGeneratorARM::visitCompareBAndBranch(LCompareBAndBranch* lir)
+{
+    MCompare* mir = lir->cmpMir();
+    const ValueOperand lhs = ToValue(lir, LCompareBAndBranch::Lhs);
+    const LAllocation* rhs = lir->rhs();
+
+    MOZ_ASSERT(mir->jsop() == JSOP_STRICTEQ || mir->jsop() == JSOP_STRICTNE);
+
+    Assembler::Condition cond = masm.testBoolean(Assembler::NotEqual, lhs);
+    jumpToBlock((mir->jsop() == JSOP_STRICTEQ) ? lir->ifFalse() : lir->ifTrue(), cond);
+
+    if (rhs->isConstant())
+        masm.cmp32(lhs.payloadReg(), Imm32(rhs->toConstant()->toBoolean()));
+    else
+        masm.cmp32(lhs.payloadReg(), ToRegister(rhs));
+    emitBranch(JSOpToCondition(mir->compareType(), mir->jsop()), lir->ifTrue(), lir->ifFalse());
+}
+
+void
+CodeGeneratorARM::visitCompareBitwise(LCompareBitwise* lir)
+{
+    MCompare* mir = lir->mir();
+    Assembler::Condition cond = JSOpToCondition(mir->compareType(), mir->jsop());
+    const ValueOperand lhs = ToValue(lir, LCompareBitwise::LhsInput);
+    const ValueOperand rhs = ToValue(lir, LCompareBitwise::RhsInput);
+    const Register output = ToRegister(lir->output());
+
+    MOZ_ASSERT(mir->jsop() == JSOP_EQ || mir->jsop() == JSOP_STRICTEQ ||
+               mir->jsop() == JSOP_NE || mir->jsop() == JSOP_STRICTNE);
+
+    Label notEqual, done;
+    masm.cmp32(lhs.typeReg(), rhs.typeReg());
+    masm.j(Assembler::NotEqual, &notEqual);
+    {
+        masm.cmp32(lhs.payloadReg(), rhs.payloadReg());
+        masm.emitSet(cond, output);
+        masm.jump(&done);
+    }
+    masm.bind(&notEqual);
+    {
+        masm.move32(Imm32(cond == Assembler::NotEqual), output);
+    }
+
+    masm.bind(&done);
+}
+
+void
+CodeGeneratorARM::visitCompareBitwiseAndBranch(LCompareBitwiseAndBranch* lir)
+{
+    MCompare* mir = lir->cmpMir();
+    Assembler::Condition cond = JSOpToCondition(mir->compareType(), mir->jsop());
+    const ValueOperand lhs = ToValue(lir, LCompareBitwiseAndBranch::LhsInput);
+    const ValueOperand rhs = ToValue(lir, LCompareBitwiseAndBranch::RhsInput);
+
+    MOZ_ASSERT(mir->jsop() == JSOP_EQ || mir->jsop() == JSOP_STRICTEQ ||
+               mir->jsop() == JSOP_NE || mir->jsop() == JSOP_STRICTNE);
+
+    MBasicBlock* notEqual = (cond == Assembler::Equal) ? lir->ifFalse() : lir->ifTrue();
+
+    masm.cmp32(lhs.typeReg(), rhs.typeReg());
+    jumpToBlock(notEqual, Assembler::NotEqual);
+    masm.cmp32(lhs.payloadReg(), rhs.payloadReg());
+    emitBranch(cond, lir->ifTrue(), lir->ifFalse());
+}
+
+void
+CodeGeneratorARM::visitBitAndAndBranch(LBitAndAndBranch* baab)
+{
+    ScratchRegisterScope scratch(masm);
+    if (baab->right()->isConstant())
+        masm.ma_tst(ToRegister(baab->left()), Imm32(ToInt32(baab->right())), scratch);
+    else
+        masm.ma_tst(ToRegister(baab->left()), ToRegister(baab->right()));
+    emitBranch(Assembler::NonZero, baab->ifTrue(), baab->ifFalse());
+}
+
+void
+CodeGeneratorARM::visitWasmUint32ToDouble(LWasmUint32ToDouble* lir)
+{
+    masm.convertUInt32ToDouble(ToRegister(lir->input()), ToFloatRegister(lir->output()));
+}
+
+void
+CodeGeneratorARM::visitWasmUint32ToFloat32(LWasmUint32ToFloat32* lir)
+{
+    masm.convertUInt32ToFloat32(ToRegister(lir->input()), ToFloatRegister(lir->output()));
+}
+
+void
+CodeGeneratorARM::visitNotI(LNotI* ins)
+{
+    // It is hard to optimize !x, so just do it the basic way for now.
+    masm.as_cmp(ToRegister(ins->input()), Imm8(0));
+    masm.emitSet(Assembler::Equal, ToRegister(ins->output()));
+}
+
+void
+CodeGeneratorARM::visitNotI64(LNotI64* lir)
+{
+    Register64 input = ToRegister64(lir->getInt64Operand(0));
+    Register output = ToRegister(lir->output());
+
+    masm.ma_orr(input.low, input.high, output);
+    masm.as_cmp(output, Imm8(0));
+    masm.emitSet(Assembler::Equal, output);
+}
+
+void
+CodeGeneratorARM::visitNotD(LNotD* ins)
+{
+    // Since this operation is not, we want to set a bit if the double is
+    // falsey, which means 0.0, -0.0 or NaN. When comparing with 0, an input of
+    // 0 will set the Z bit (30) and NaN will set the V bit (28) of the APSR.
+    FloatRegister opd = ToFloatRegister(ins->input());
+    Register dest = ToRegister(ins->output());
+
+    // Do the compare.
+    masm.ma_vcmpz(opd);
+    // TODO There are three variations here to compare performance-wise.
+    bool nocond = true;
+    if (nocond) {
+        // Load the value into the dest register.
+        masm.as_vmrs(dest);
+        masm.ma_lsr(Imm32(28), dest, dest);
+        // 28 + 2 = 30
+        masm.ma_alu(dest, lsr(dest, 2), dest, OpOrr);
+        masm.as_and(dest, dest, Imm8(1));
+    } else {
+        masm.as_vmrs(pc);
+        masm.ma_mov(Imm32(0), dest);
+        masm.ma_mov(Imm32(1), dest, Assembler::Equal);
+        masm.ma_mov(Imm32(1), dest, Assembler::Overflow);
+    }
+}
+
+void
+CodeGeneratorARM::visitNotF(LNotF* ins)
+{
+    // Since this operation is not, we want to set a bit if the double is
+    // falsey, which means 0.0, -0.0 or NaN. When comparing with 0, an input of
+    // 0 will set the Z bit (30) and NaN will set the V bit (28) of the APSR.
+    FloatRegister opd = ToFloatRegister(ins->input());
+    Register dest = ToRegister(ins->output());
+
+    // Do the compare.
+    masm.ma_vcmpz_f32(opd);
+    // TODO There are three variations here to compare performance-wise.
+    bool nocond = true;
+    if (nocond) {
+        // Load the value into the dest register.
+        masm.as_vmrs(dest);
+        masm.ma_lsr(Imm32(28), dest, dest);
+        // 28 + 2 = 30
+        masm.ma_alu(dest, lsr(dest, 2), dest, OpOrr);
+        masm.as_and(dest, dest, Imm8(1));
+    } else {
+        masm.as_vmrs(pc);
+        masm.ma_mov(Imm32(0), dest);
+        masm.ma_mov(Imm32(1), dest, Assembler::Equal);
+        masm.ma_mov(Imm32(1), dest, Assembler::Overflow);
+    }
+}
+
+void
+CodeGeneratorARM::visitGuardShape(LGuardShape* guard)
+{
+    Register obj = ToRegister(guard->input());
+    Register tmp = ToRegister(guard->tempInt());
+
+    ScratchRegisterScope scratch(masm);
+    masm.ma_ldr(DTRAddr(obj, DtrOffImm(ShapedObject::offsetOfShape())), tmp);
+    masm.ma_cmp(tmp, ImmGCPtr(guard->mir()->shape()), scratch);
+
+    bailoutIf(Assembler::NotEqual, guard->snapshot());
+}
+
+void
+CodeGeneratorARM::visitGuardObjectGroup(LGuardObjectGroup* guard)
+{
+    Register obj = ToRegister(guard->input());
+    Register tmp = ToRegister(guard->tempInt());
+    MOZ_ASSERT(obj != tmp);
+
+    ScratchRegisterScope scratch(masm);
+    masm.ma_ldr(DTRAddr(obj, DtrOffImm(JSObject::offsetOfGroup())), tmp);
+    masm.ma_cmp(tmp, ImmGCPtr(guard->mir()->group()), scratch);
+
+    Assembler::Condition cond =
+        guard->mir()->bailOnEquality() ? Assembler::Equal : Assembler::NotEqual;
+    bailoutIf(cond, guard->snapshot());
+}
+
+void
+CodeGeneratorARM::visitGuardClass(LGuardClass* guard)
+{
+    Register obj = ToRegister(guard->input());
+    Register tmp = ToRegister(guard->tempInt());
+
+    ScratchRegisterScope scratch(masm);
+
+    masm.loadObjClass(obj, tmp);
+    masm.ma_cmp(tmp, Imm32((uint32_t)guard->mir()->getClass()), scratch);
+    bailoutIf(Assembler::NotEqual, guard->snapshot());
+}
+
+void
+CodeGeneratorARM::generateInvalidateEpilogue()
+{
+    // Ensure that there is enough space in the buffer for the OsiPoint patching
+    // to occur. Otherwise, we could overwrite the invalidation epilogue.
+    for (size_t i = 0; i < sizeof(void*); i += Assembler::NopSize())
+        masm.nop();
+
+    masm.bind(&invalidate_);
+
+    // Push the return address of the point that we bailed out at onto the stack.
+    masm.Push(lr);
+
+    // Push the Ion script onto the stack (when we determine what that pointer is).
+    invalidateEpilogueData_ = masm.pushWithPatch(ImmWord(uintptr_t(-1)));
+    JitCode* thunk = gen->jitRuntime()->getInvalidationThunk();
+
+    masm.branch(thunk);
+
+    // We should never reach this point in JIT code -- the invalidation thunk
+    // should pop the invalidated JS frame and return directly to its caller.
+    masm.assumeUnreachable("Should have returned directly to its caller instead of here.");
+}
+
+void
+CodeGeneratorARM::visitLoadTypedArrayElementStatic(LLoadTypedArrayElementStatic* ins)
+{
+    MOZ_CRASH("NYI");
+}
+
+void
+CodeGeneratorARM::visitStoreTypedArrayElementStatic(LStoreTypedArrayElementStatic* ins)
+{
+    MOZ_CRASH("NYI");
+}
+
+void
+CodeGeneratorARM::visitCompareExchangeTypedArrayElement(LCompareExchangeTypedArrayElement* lir)
+{
+    Register elements = ToRegister(lir->elements());
+    AnyRegister output = ToAnyRegister(lir->output());
+    Register temp = lir->temp()->isBogusTemp() ? InvalidReg : ToRegister(lir->temp());
+
+    Register oldval = ToRegister(lir->oldval());
+    Register newval = ToRegister(lir->newval());
+
+    Scalar::Type arrayType = lir->mir()->arrayType();
+    int width = Scalar::byteSize(arrayType);
+
+    if (lir->index()->isConstant()) {
+        Address dest(elements, ToInt32(lir->index()) * width);
+        masm.compareExchangeToTypedIntArray(arrayType, dest, oldval, newval, temp, output);
+    } else {
+        BaseIndex dest(elements, ToRegister(lir->index()), ScaleFromElemWidth(width));
+        masm.compareExchangeToTypedIntArray(arrayType, dest, oldval, newval, temp, output);
+    }
+}
+
+void
+CodeGeneratorARM::visitAtomicExchangeTypedArrayElement(LAtomicExchangeTypedArrayElement* lir)
+{
+    Register elements = ToRegister(lir->elements());
+    AnyRegister output = ToAnyRegister(lir->output());
+    Register temp = lir->temp()->isBogusTemp() ? InvalidReg : ToRegister(lir->temp());
+
+    Register value = ToRegister(lir->value());
+
+    Scalar::Type arrayType = lir->mir()->arrayType();
+    int width = Scalar::byteSize(arrayType);
+
+    if (lir->index()->isConstant()) {
+        Address dest(elements, ToInt32(lir->index()) * width);
+        masm.atomicExchangeToTypedIntArray(arrayType, dest, value, temp, output);
+    } else {
+        BaseIndex dest(elements, ToRegister(lir->index()), ScaleFromElemWidth(width));
+        masm.atomicExchangeToTypedIntArray(arrayType, dest, value, temp, output);
+    }
+}
+
+template<typename S, typename T>
+void
+CodeGeneratorARM::atomicBinopToTypedIntArray(AtomicOp op, Scalar::Type arrayType,
+                                             const S& value, const T& mem, Register flagTemp,
+                                             Register outTemp, AnyRegister output)
+{
+    MOZ_ASSERT(flagTemp != InvalidReg);
+    MOZ_ASSERT_IF(arrayType == Scalar::Uint32, outTemp != InvalidReg);
+
+    switch (arrayType) {
+      case Scalar::Int8:
+        switch (op) {
+          case AtomicFetchAddOp:
+            masm.atomicFetchAdd8SignExtend(value, mem, flagTemp, output.gpr());
+            break;
+          case AtomicFetchSubOp:
+            masm.atomicFetchSub8SignExtend(value, mem, flagTemp, output.gpr());
+            break;
+          case AtomicFetchAndOp:
+            masm.atomicFetchAnd8SignExtend(value, mem, flagTemp, output.gpr());
+            break;
+          case AtomicFetchOrOp:
+            masm.atomicFetchOr8SignExtend(value, mem, flagTemp, output.gpr());
+            break;
+          case AtomicFetchXorOp:
+            masm.atomicFetchXor8SignExtend(value, mem, flagTemp, output.gpr());
+            break;
+          default:
+            MOZ_CRASH("Invalid typed array atomic operation");
+        }
+        break;
+      case Scalar::Uint8:
+        switch (op) {
+          case AtomicFetchAddOp:
+            masm.atomicFetchAdd8ZeroExtend(value, mem, flagTemp, output.gpr());
+            break;
+          case AtomicFetchSubOp:
+            masm.atomicFetchSub8ZeroExtend(value, mem, flagTemp, output.gpr());
+            break;
+          case AtomicFetchAndOp:
+            masm.atomicFetchAnd8ZeroExtend(value, mem, flagTemp, output.gpr());
+            break;
+          case AtomicFetchOrOp:
+            masm.atomicFetchOr8ZeroExtend(value, mem, flagTemp, output.gpr());
+            break;
+          case AtomicFetchXorOp:
+            masm.atomicFetchXor8ZeroExtend(value, mem, flagTemp, output.gpr());
+            break;
+          default:
+            MOZ_CRASH("Invalid typed array atomic operation");
+        }
+        break;
+      case Scalar::Int16:
+        switch (op) {
+          case AtomicFetchAddOp:
+            masm.atomicFetchAdd16SignExtend(value, mem, flagTemp, output.gpr());
+            break;
+          case AtomicFetchSubOp:
+            masm.atomicFetchSub16SignExtend(value, mem, flagTemp, output.gpr());
+            break;
+          case AtomicFetchAndOp:
+            masm.atomicFetchAnd16SignExtend(value, mem, flagTemp, output.gpr());
+            break;
+          case AtomicFetchOrOp:
+            masm.atomicFetchOr16SignExtend(value, mem, flagTemp, output.gpr());
+            break;
+          case AtomicFetchXorOp:
+            masm.atomicFetchXor16SignExtend(value, mem, flagTemp, output.gpr());
+            break;
+          default:
+            MOZ_CRASH("Invalid typed array atomic operation");
+        }
+        break;
+      case Scalar::Uint16:
+        switch (op) {
+          case AtomicFetchAddOp:
+            masm.atomicFetchAdd16ZeroExtend(value, mem, flagTemp, output.gpr());
+            break;
+          case AtomicFetchSubOp:
+            masm.atomicFetchSub16ZeroExtend(value, mem, flagTemp, output.gpr());
+            break;
+          case AtomicFetchAndOp:
+            masm.atomicFetchAnd16ZeroExtend(value, mem, flagTemp, output.gpr());
+            break;
+          case AtomicFetchOrOp:
+            masm.atomicFetchOr16ZeroExtend(value, mem, flagTemp, output.gpr());
+            break;
+          case AtomicFetchXorOp:
+            masm.atomicFetchXor16ZeroExtend(value, mem, flagTemp, output.gpr());
+            break;
+          default:
+            MOZ_CRASH("Invalid typed array atomic operation");
+        }
+        break;
+      case Scalar::Int32:
+        switch (op) {
+          case AtomicFetchAddOp:
+            masm.atomicFetchAdd32(value, mem, flagTemp, output.gpr());
+            break;
+          case AtomicFetchSubOp:
+            masm.atomicFetchSub32(value, mem, flagTemp, output.gpr());
+            break;
+          case AtomicFetchAndOp:
+            masm.atomicFetchAnd32(value, mem, flagTemp, output.gpr());
+            break;
+          case AtomicFetchOrOp:
+            masm.atomicFetchOr32(value, mem, flagTemp, output.gpr());
+            break;
+          case AtomicFetchXorOp:
+            masm.atomicFetchXor32(value, mem, flagTemp, output.gpr());
+            break;
+          default:
+            MOZ_CRASH("Invalid typed array atomic operation");
+        }
+        break;
+      case Scalar::Uint32:
+        // At the moment, the code in MCallOptimize.cpp requires the output
+        // type to be double for uint32 arrays.  See bug 1077305.
+        MOZ_ASSERT(output.isFloat());
+        switch (op) {
+          case AtomicFetchAddOp:
+            masm.atomicFetchAdd32(value, mem, flagTemp, outTemp);
+            break;
+          case AtomicFetchSubOp:
+            masm.atomicFetchSub32(value, mem, flagTemp, outTemp);
+            break;
+          case AtomicFetchAndOp:
+            masm.atomicFetchAnd32(value, mem, flagTemp, outTemp);
+            break;
+          case AtomicFetchOrOp:
+            masm.atomicFetchOr32(value, mem, flagTemp, outTemp);
+            break;
+          case AtomicFetchXorOp:
+            masm.atomicFetchXor32(value, mem, flagTemp, outTemp);
+            break;
+          default:
+            MOZ_CRASH("Invalid typed array atomic operation");
+        }
+        masm.convertUInt32ToDouble(outTemp, output.fpu());
+        break;
+      default:
+        MOZ_CRASH("Invalid typed array type");
+    }
+}
+
+template void
+CodeGeneratorARM::atomicBinopToTypedIntArray(AtomicOp op, Scalar::Type arrayType,
+                                             const Imm32& value, const Address& mem,
+                                             Register flagTemp, Register outTemp,
+                                             AnyRegister output);
+template void
+CodeGeneratorARM::atomicBinopToTypedIntArray(AtomicOp op, Scalar::Type arrayType,
+                                             const Imm32& value, const BaseIndex& mem,
+                                             Register flagTemp, Register outTemp,
+                                             AnyRegister output);
+template void
+CodeGeneratorARM::atomicBinopToTypedIntArray(AtomicOp op, Scalar::Type arrayType,
+                                             const Register& value, const Address& mem,
+                                             Register flagTemp, Register outTemp,
+                                             AnyRegister output);
+template void
+CodeGeneratorARM::atomicBinopToTypedIntArray(AtomicOp op, Scalar::Type arrayType,
+                                             const Register& value, const BaseIndex& mem,
+                                             Register flagTemp, Register outTemp,
+                                             AnyRegister output);
+
+// Binary operation for effect, result discarded.
+template<typename S, typename T>
+void
+CodeGeneratorARM::atomicBinopToTypedIntArray(AtomicOp op, Scalar::Type arrayType, const S& value,
+                                             const T& mem, Register flagTemp)
+{
+    MOZ_ASSERT(flagTemp != InvalidReg);
+
+    switch (arrayType) {
+      case Scalar::Int8:
+      case Scalar::Uint8:
+        switch (op) {
+          case AtomicFetchAddOp:
+            masm.atomicAdd8(value, mem, flagTemp);
+            break;
+          case AtomicFetchSubOp:
+            masm.atomicSub8(value, mem, flagTemp);
+            break;
+          case AtomicFetchAndOp:
+            masm.atomicAnd8(value, mem, flagTemp);
+            break;
+          case AtomicFetchOrOp:
+            masm.atomicOr8(value, mem, flagTemp);
+            break;
+          case AtomicFetchXorOp:
+            masm.atomicXor8(value, mem, flagTemp);
+            break;
+          default:
+            MOZ_CRASH("Invalid typed array atomic operation");
+        }
+        break;
+      case Scalar::Int16:
+      case Scalar::Uint16:
+        switch (op) {
+          case AtomicFetchAddOp:
+            masm.atomicAdd16(value, mem, flagTemp);
+            break;
+          case AtomicFetchSubOp:
+            masm.atomicSub16(value, mem, flagTemp);
+            break;
+          case AtomicFetchAndOp:
+            masm.atomicAnd16(value, mem, flagTemp);
+            break;
+          case AtomicFetchOrOp:
+            masm.atomicOr16(value, mem, flagTemp);
+            break;
+          case AtomicFetchXorOp:
+            masm.atomicXor16(value, mem, flagTemp);
+            break;
+          default:
+            MOZ_CRASH("Invalid typed array atomic operation");
+        }
+        break;
+      case Scalar::Int32:
+      case Scalar::Uint32:
+        switch (op) {
+          case AtomicFetchAddOp:
+            masm.atomicAdd32(value, mem, flagTemp);
+            break;
+          case AtomicFetchSubOp:
+            masm.atomicSub32(value, mem, flagTemp);
+            break;
+          case AtomicFetchAndOp:
+            masm.atomicAnd32(value, mem, flagTemp);
+            break;
+          case AtomicFetchOrOp:
+            masm.atomicOr32(value, mem, flagTemp);
+            break;
+          case AtomicFetchXorOp:
+            masm.atomicXor32(value, mem, flagTemp);
+            break;
+          default:
+            MOZ_CRASH("Invalid typed array atomic operation");
+        }
+        break;
+      default:
+        MOZ_CRASH("Invalid typed array type");
+    }
+}
+
+template void
+CodeGeneratorARM::atomicBinopToTypedIntArray(AtomicOp op, Scalar::Type arrayType,
+                                             const Imm32& value, const Address& mem,
+                                             Register flagTemp);
+template void
+CodeGeneratorARM::atomicBinopToTypedIntArray(AtomicOp op, Scalar::Type arrayType,
+                                             const Imm32& value, const BaseIndex& mem,
+                                             Register flagTemp);
+template void
+CodeGeneratorARM::atomicBinopToTypedIntArray(AtomicOp op, Scalar::Type arrayType,
+                                             const Register& value, const Address& mem,
+                                             Register flagTemp);
+template void
+CodeGeneratorARM::atomicBinopToTypedIntArray(AtomicOp op, Scalar::Type arrayType,
+                                             const Register& value, const BaseIndex& mem,
+                                             Register flagTemp);
+
+
+template <typename T>
+static inline void
+AtomicBinopToTypedArray(CodeGeneratorARM* cg, AtomicOp op,
+                        Scalar::Type arrayType, const LAllocation* value, const T& mem,
+                        Register flagTemp, Register outTemp, AnyRegister output)
+{
+    if (value->isConstant())
+        cg->atomicBinopToTypedIntArray(op, arrayType, Imm32(ToInt32(value)), mem, flagTemp, outTemp, output);
+    else
+        cg->atomicBinopToTypedIntArray(op, arrayType, ToRegister(value), mem, flagTemp, outTemp, output);
+}
+
+void
+CodeGeneratorARM::visitAtomicTypedArrayElementBinop(LAtomicTypedArrayElementBinop* lir)
+{
+    MOZ_ASSERT(lir->mir()->hasUses());
+
+    AnyRegister output = ToAnyRegister(lir->output());
+    Register elements = ToRegister(lir->elements());
+    Register flagTemp = ToRegister(lir->temp1());
+    Register outTemp = lir->temp2()->isBogusTemp() ? InvalidReg : ToRegister(lir->temp2());
+    const LAllocation* value = lir->value();
+
+    Scalar::Type arrayType = lir->mir()->arrayType();
+    int width = Scalar::byteSize(arrayType);
+
+    if (lir->index()->isConstant()) {
+        Address mem(elements, ToInt32(lir->index()) * width);
+        AtomicBinopToTypedArray(this, lir->mir()->operation(), arrayType, value, mem, flagTemp, outTemp, output);
+    } else {
+        BaseIndex mem(elements, ToRegister(lir->index()), ScaleFromElemWidth(width));
+        AtomicBinopToTypedArray(this, lir->mir()->operation(), arrayType, value, mem, flagTemp, outTemp, output);
+    }
+}
+
+template <typename T>
+static inline void
+AtomicBinopToTypedArray(CodeGeneratorARM* cg, AtomicOp op, Scalar::Type arrayType,
+                        const LAllocation* value, const T& mem, Register flagTemp)
+{
+    if (value->isConstant())
+        cg->atomicBinopToTypedIntArray(op, arrayType, Imm32(ToInt32(value)), mem, flagTemp);
+    else
+        cg->atomicBinopToTypedIntArray(op, arrayType, ToRegister(value), mem, flagTemp);
+}
+
+void
+CodeGeneratorARM::visitAtomicTypedArrayElementBinopForEffect(LAtomicTypedArrayElementBinopForEffect* lir)
+{
+    MOZ_ASSERT(!lir->mir()->hasUses());
+
+    Register elements = ToRegister(lir->elements());
+    Register flagTemp = ToRegister(lir->flagTemp());
+    const LAllocation* value = lir->value();
+    Scalar::Type arrayType = lir->mir()->arrayType();
+    int width = Scalar::byteSize(arrayType);
+
+    if (lir->index()->isConstant()) {
+        Address mem(elements, ToInt32(lir->index()) * width);
+        AtomicBinopToTypedArray(this, lir->mir()->operation(), arrayType, value, mem, flagTemp);
+    } else {
+        BaseIndex mem(elements, ToRegister(lir->index()), ScaleFromElemWidth(width));
+        AtomicBinopToTypedArray(this, lir->mir()->operation(), arrayType, value, mem, flagTemp);
+    }
+}
+
+void
+CodeGeneratorARM::visitWasmSelect(LWasmSelect* ins)
+{
+    MIRType mirType = ins->mir()->type();
+
+    Register cond = ToRegister(ins->condExpr());
+    masm.as_cmp(cond, Imm8(0));
+
+    if (mirType == MIRType::Int32) {
+        Register falseExpr = ToRegister(ins->falseExpr());
+        Register out = ToRegister(ins->output());
+        MOZ_ASSERT(ToRegister(ins->trueExpr()) == out, "true expr input is reused for output");
+        masm.ma_mov(falseExpr, out, LeaveCC, Assembler::Zero);
+        return;
+    }
+
+    FloatRegister out = ToFloatRegister(ins->output());
+    MOZ_ASSERT(ToFloatRegister(ins->trueExpr()) == out, "true expr input is reused for output");
+
+    FloatRegister falseExpr = ToFloatRegister(ins->falseExpr());
+
+    if (mirType == MIRType::Double)
+        masm.moveDouble(falseExpr, out, Assembler::Zero);
+    else if (mirType == MIRType::Float32)
+        masm.moveFloat32(falseExpr, out, Assembler::Zero);
+    else
+        MOZ_CRASH("unhandled type in visitWasmSelect!");
+}
+
+void
+CodeGeneratorARM::visitWasmReinterpret(LWasmReinterpret* lir)
+{
+    MOZ_ASSERT(gen->compilingWasm());
+    MWasmReinterpret* ins = lir->mir();
+
+    MIRType to = ins->type();
+    DebugOnly<MIRType> from = ins->input()->type();
+
+    switch (to) {
+      case MIRType::Int32:
+        MOZ_ASSERT(from == MIRType::Float32);
+        masm.ma_vxfer(ToFloatRegister(lir->input()), ToRegister(lir->output()));
+        break;
+      case MIRType::Float32:
+        MOZ_ASSERT(from == MIRType::Int32);
+        masm.ma_vxfer(ToRegister(lir->input()), ToFloatRegister(lir->output()));
+        break;
+      case MIRType::Double:
+      case MIRType::Int64:
+        MOZ_CRASH("not handled by this LIR opcode");
+      default:
+        MOZ_CRASH("unexpected WasmReinterpret");
+    }
+}
+
+void
+CodeGeneratorARM::emitWasmCall(LWasmCallBase* ins)
+{
+    MWasmCall* mir = ins->mir();
+
+    if (UseHardFpABI() || mir->callee().which() != wasm::CalleeDesc::Builtin) {
+        emitWasmCallBase(ins);
+        return;
+    }
+
+    // The soft ABI passes floating point arguments in GPRs. Since basically
+    // nothing is set up to handle this, the values are placed in the
+    // corresponding VFP registers, then transferred to GPRs immediately
+    // before the call. The mapping is sN <-> rN, where double registers
+    // can be treated as their two component single registers.
+
+    for (unsigned i = 0, e = ins->numOperands(); i < e; i++) {
+        LAllocation* a = ins->getOperand(i);
+        if (a->isFloatReg()) {
+            FloatRegister fr = ToFloatRegister(a);
+            if (fr.isDouble()) {
+                uint32_t srcId = fr.singleOverlay().id();
+                masm.ma_vxfer(fr, Register::FromCode(srcId), Register::FromCode(srcId + 1));
+            } else {
+                uint32_t srcId = fr.id();
+                masm.ma_vxfer(fr, Register::FromCode(srcId));
+            }
+        }
+    }
+
+    emitWasmCallBase(ins);
+
+    switch (mir->type()) {
+      case MIRType::Double:
+        masm.ma_vxfer(r0, r1, d0);
+        break;
+      case MIRType::Float32:
+        masm.as_vxfer(r0, InvalidReg, VFPRegister(d0).singleOverlay(), Assembler::CoreToFloat);
+        break;
+      default:
+        break;
+    }
+}
+
+void
+CodeGeneratorARM::visitWasmCall(LWasmCall* ins)
+{
+    emitWasmCall(ins);
+}
+
+void
+CodeGeneratorARM::visitWasmCallI64(LWasmCallI64* ins)
+{
+    emitWasmCall(ins);
+}
+
+void
+CodeGeneratorARM::visitAsmJSLoadHeap(LAsmJSLoadHeap* ins)
+{
+    const MAsmJSLoadHeap* mir = ins->mir();
+    MOZ_ASSERT(mir->offset() == 0);
+
+    const LAllocation* ptr = ins->ptr();
+
+    bool isSigned;
+    int size;
+    bool isFloat = false;
+    switch (mir->accessType()) {
+      case Scalar::Int8:    isSigned = true;  size =  8; break;
+      case Scalar::Uint8:   isSigned = false; size =  8; break;
+      case Scalar::Int16:   isSigned = true;  size = 16; break;
+      case Scalar::Uint16:  isSigned = false; size = 16; break;
+      case Scalar::Int32:
+      case Scalar::Uint32:  isSigned = true;  size = 32; break;
+      case Scalar::Float64: isFloat = true;   size = 64; break;
+      case Scalar::Float32: isFloat = true;   size = 32; break;
+      default: MOZ_CRASH("unexpected array type");
+    }
+
+    if (ptr->isConstant()) {
+        MOZ_ASSERT(!mir->needsBoundsCheck());
+        int32_t ptrImm = ptr->toConstant()->toInt32();
+        MOZ_ASSERT(ptrImm >= 0);
+        if (isFloat) {
+            ScratchRegisterScope scratch(masm);
+            VFPRegister vd(ToFloatRegister(ins->output()));
+            if (size == 32)
+                masm.ma_vldr(Address(HeapReg, ptrImm), vd.singleOverlay(), scratch, Assembler::Always);
+            else
+                masm.ma_vldr(Address(HeapReg, ptrImm), vd, scratch, Assembler::Always);
+        }  else {
+            ScratchRegisterScope scratch(masm);
+            masm.ma_dataTransferN(IsLoad, size, isSigned, HeapReg, Imm32(ptrImm),
+                                  ToRegister(ins->output()), scratch, Offset, Assembler::Always);
+        }
+    } else {
+        ScratchRegisterScope scratch(masm);
+        Register ptrReg = ToRegister(ptr);
+        if (isFloat) {
+            FloatRegister output = ToFloatRegister(ins->output());
+            if (size == 32)
+                output = output.singleOverlay();
+
+            Assembler::Condition cond = Assembler::Always;
+            if (mir->needsBoundsCheck()) {
+                BufferOffset cmp = masm.as_cmp(ptrReg, Imm8(0));
+                masm.append(wasm::BoundsCheck(cmp.getOffset()));
+
+                size_t nanOffset = size == 32 ? wasm::NaN32GlobalDataOffset : wasm::NaN64GlobalDataOffset;
+                masm.ma_vldr(Address(GlobalReg, nanOffset - WasmGlobalRegBias), output, scratch,
+                             Assembler::AboveOrEqual);
+                cond = Assembler::Below;
+            }
+
+            masm.ma_vldr(output, HeapReg, ptrReg, scratch, 0, cond);
+        } else {
+            Register output = ToRegister(ins->output());
+
+            Assembler::Condition cond = Assembler::Always;
+            if (mir->needsBoundsCheck()) {
+                uint32_t cmpOffset = masm.as_cmp(ptrReg, Imm8(0)).getOffset();
+                masm.append(wasm::BoundsCheck(cmpOffset));
+
+                masm.ma_mov(Imm32(0), output, Assembler::AboveOrEqual);
+                cond = Assembler::Below;
+            }
+
+            masm.ma_dataTransferN(IsLoad, size, isSigned, HeapReg, ptrReg, output, scratch, Offset, cond);
+        }
+    }
+}
+
+template <typename T>
+void
+CodeGeneratorARM::emitWasmLoad(T* lir)
+{
+    const MWasmLoad* mir = lir->mir();
+
+    uint32_t offset = mir->access().offset();
+    MOZ_ASSERT(offset < wasm::OffsetGuardLimit);
+
+    Register ptr = ToRegister(lir->ptr());
+    Scalar::Type type = mir->access().type();
+
+    // Maybe add the offset.
+    if (offset || type == Scalar::Int64) {
+        ScratchRegisterScope scratch(masm);
+        Register ptrPlusOffset = ToRegister(lir->ptrCopy());
+        if (offset)
+            masm.ma_add(Imm32(offset), ptrPlusOffset, scratch);
+        ptr = ptrPlusOffset;
+    } else {
+        MOZ_ASSERT(lir->ptrCopy()->isBogusTemp());
+    }
+
+    bool isSigned = type == Scalar::Int8 || type == Scalar::Int16 || type == Scalar::Int32 ||
+                    type == Scalar::Int64;
+    unsigned byteSize = mir->access().byteSize();
+
+    masm.memoryBarrier(mir->access().barrierBefore());
+
+    BufferOffset load;
+    if (mir->type() == MIRType::Int64) {
+        Register64 output = ToOutRegister64(lir);
+        if (type == Scalar::Int64) {
+            MOZ_ASSERT(INT64LOW_OFFSET == 0);
+
+            load = masm.ma_dataTransferN(IsLoad, 32, /* signed = */ false, HeapReg, ptr, output.low);
+            masm.append(mir->access(), load.getOffset(), masm.framePushed());
+
+            masm.as_add(ptr, ptr, Imm8(INT64HIGH_OFFSET));
+
+            load = masm.ma_dataTransferN(IsLoad, 32, isSigned, HeapReg, ptr, output.high);
+            masm.append(mir->access(), load.getOffset(), masm.framePushed());
+        } else {
+            load = masm.ma_dataTransferN(IsLoad, byteSize * 8, isSigned, HeapReg, ptr, output.low);
+            masm.append(mir->access(), load.getOffset(), masm.framePushed());
+
+            if (isSigned)
+                masm.ma_asr(Imm32(31), output.low, output.high);
+            else
+                masm.ma_mov(Imm32(0), output.high);
+        }
+    } else {
+        AnyRegister output = ToAnyRegister(lir->output());
+        bool isFloat = output.isFloat();
+        if (isFloat) {
+            MOZ_ASSERT((byteSize == 4) == output.fpu().isSingle());
+            ScratchRegisterScope scratch(masm);
+            masm.ma_add(HeapReg, ptr, scratch);
+
+            load = masm.ma_vldr(Operand(Address(scratch, 0)).toVFPAddr(), output.fpu());
+            masm.append(mir->access(), load.getOffset(), masm.framePushed());
+        } else {
+            load = masm.ma_dataTransferN(IsLoad, byteSize * 8, isSigned, HeapReg, ptr, output.gpr());
+            masm.append(mir->access(), load.getOffset(), masm.framePushed());
+        }
+    }
+
+    masm.memoryBarrier(mir->access().barrierAfter());
+}
+
+void
+CodeGeneratorARM::visitWasmLoad(LWasmLoad* lir)
+{
+    emitWasmLoad(lir);
+}
+
+void
+CodeGeneratorARM::visitWasmLoadI64(LWasmLoadI64* lir)
+{
+    emitWasmLoad(lir);
+}
+
+template<typename T>
+void
+CodeGeneratorARM::emitWasmUnalignedLoad(T* lir)
+{
+    const MWasmLoad* mir = lir->mir();
+
+    uint32_t offset = mir->access().offset();
+    MOZ_ASSERT(offset < wasm::OffsetGuardLimit);
+
+    Register ptr = ToRegister(lir->ptrCopy());
+    if (offset) {
+        ScratchRegisterScope scratch(masm);
+        masm.ma_add(Imm32(offset), ptr, scratch);
+    }
+
+    // Add HeapReg to ptr, so we can use base+index addressing in the byte loads.
+    masm.ma_add(HeapReg, ptr);
+
+    unsigned byteSize = mir->access().byteSize();
+    Scalar::Type type = mir->access().type();
+    bool isSigned = type == Scalar::Int8 || type == Scalar::Int16 || type == Scalar::Int32 ||
+                    type == Scalar::Int64;
+
+    MIRType mirType = mir->type();
+
+    Register tmp = ToRegister(lir->getTemp(1));
+
+    Register low;
+    if (IsFloatingPointType(mirType))
+        low = ToRegister(lir->getTemp(2));
+    else if (mirType == MIRType::Int64)
+        low = ToOutRegister64(lir).low;
+    else
+        low = ToRegister(lir->output());
+
+    MOZ_ASSERT(low != tmp);
+    MOZ_ASSERT(low != ptr);
+
+    masm.memoryBarrier(mir->access().barrierBefore());
+
+    masm.emitUnalignedLoad(isSigned, Min(byteSize, 4u), ptr, tmp, low);
+
+    if (IsFloatingPointType(mirType)) {
+        FloatRegister output = ToFloatRegister(lir->output());
+        if (byteSize == 4) {
+            MOZ_ASSERT(output.isSingle());
+            masm.ma_vxfer(low, output);
+        } else {
+            MOZ_ASSERT(byteSize == 8);
+            MOZ_ASSERT(output.isDouble());
+            Register high = ToRegister(lir->getTemp(3));
+            masm.emitUnalignedLoad(/* signed */ false, 4, ptr, tmp, high, /* offset */ 4);
+            masm.ma_vxfer(low, high, output);
+        }
+    } else if (mirType == MIRType::Int64) {
+        Register64 output = ToOutRegister64(lir);
+        if (type == Scalar::Int64) {
+            MOZ_ASSERT(byteSize == 8);
+            masm.emitUnalignedLoad(isSigned, 4, ptr, tmp, output.high, /* offset */ 4);
+        } else {
+            MOZ_ASSERT(byteSize <= 4);
+            // Propagate sign.
+            if (isSigned)
+                masm.ma_asr(Imm32(31), output.low, output.high);
+            else
+                masm.ma_mov(Imm32(0), output.high);
+        }
+    }
+
+    masm.memoryBarrier(mir->access().barrierAfter());
+}
+
+void
+CodeGeneratorARM::visitWasmUnalignedLoad(LWasmUnalignedLoad* lir)
+{
+    emitWasmUnalignedLoad(lir);
+}
+
+void
+CodeGeneratorARM::visitWasmUnalignedLoadI64(LWasmUnalignedLoadI64* lir)
+{
+    emitWasmUnalignedLoad(lir);
+}
+
+void
+CodeGeneratorARM::visitWasmAddOffset(LWasmAddOffset* lir)
+{
+    MWasmAddOffset* mir = lir->mir();
+    Register base = ToRegister(lir->base());
+    Register out = ToRegister(lir->output());
+
+    ScratchRegisterScope scratch(masm);
+    masm.ma_add(base, Imm32(mir->offset()), out, scratch, SetCC);
+
+    masm.ma_b(trap(mir, wasm::Trap::OutOfBounds), Assembler::CarrySet);
+}
+
+template <typename T>
+void
+CodeGeneratorARM::emitWasmStore(T* lir)
+{
+    const MWasmStore* mir = lir->mir();
+
+    uint32_t offset = mir->access().offset();
+    MOZ_ASSERT(offset < wasm::OffsetGuardLimit);
+
+    Register ptr = ToRegister(lir->ptr());
+    unsigned byteSize = mir->access().byteSize();
+    Scalar::Type type = mir->access().type();
+
+    // Maybe add the offset.
+    if (offset || type == Scalar::Int64) {
+        ScratchRegisterScope scratch(masm);
+        Register ptrPlusOffset = ToRegister(lir->ptrCopy());
+        if (offset)
+            masm.ma_add(Imm32(offset), ptrPlusOffset, scratch);
+        ptr = ptrPlusOffset;
+    } else {
+        MOZ_ASSERT(lir->ptrCopy()->isBogusTemp());
+    }
+
+    masm.memoryBarrier(mir->access().barrierBefore());
+
+    BufferOffset store;
+    if (type == Scalar::Int64) {
+        MOZ_ASSERT(INT64LOW_OFFSET == 0);
+
+        Register64 value = ToRegister64(lir->getInt64Operand(lir->ValueIndex));
+
+        store = masm.ma_dataTransferN(IsStore, 32 /* bits */, /* signed */ false, HeapReg, ptr, value.low);
+        masm.append(mir->access(), store.getOffset(), masm.framePushed());
+
+        masm.as_add(ptr, ptr, Imm8(INT64HIGH_OFFSET));
+
+        store = masm.ma_dataTransferN(IsStore, 32 /* bits */, /* signed */ true, HeapReg, ptr, value.high);
+        masm.append(mir->access(), store.getOffset(), masm.framePushed());
+    } else {
+        AnyRegister value = ToAnyRegister(lir->getOperand(lir->ValueIndex));
+        if (value.isFloat()) {
+            ScratchRegisterScope scratch(masm);
+            FloatRegister val = value.fpu();
+            MOZ_ASSERT((byteSize == 4) == val.isSingle());
+            masm.ma_add(HeapReg, ptr, scratch);
+
+            store = masm.ma_vstr(val, Operand(Address(scratch, 0)).toVFPAddr());
+            masm.append(mir->access(), store.getOffset(), masm.framePushed());
+        } else {
+            bool isSigned = type == Scalar::Uint32 || type == Scalar::Int32; // see AsmJSStoreHeap;
+            Register val = value.gpr();
+
+            store = masm.ma_dataTransferN(IsStore, 8 * byteSize /* bits */, isSigned, HeapReg, ptr, val);
+            masm.append(mir->access(), store.getOffset(), masm.framePushed());
+        }
+    }
+
+    masm.memoryBarrier(mir->access().barrierAfter());
+}
+
+void
+CodeGeneratorARM::visitWasmStore(LWasmStore* lir)
+{
+    emitWasmStore(lir);
+}
+
+void
+CodeGeneratorARM::visitWasmStoreI64(LWasmStoreI64* lir)
+{
+    emitWasmStore(lir);
+}
+
+template<typename T>
+void
+CodeGeneratorARM::emitWasmUnalignedStore(T* lir)
+{
+    const MWasmStore* mir = lir->mir();
+
+    uint32_t offset = mir->access().offset();
+    MOZ_ASSERT(offset < wasm::OffsetGuardLimit);
+
+    Register ptr = ToRegister(lir->ptrCopy());
+    if (offset) {
+        ScratchRegisterScope scratch(masm);
+        masm.ma_add(Imm32(offset), ptr, scratch);
+    }
+
+    // Add HeapReg to ptr, so we can use base+index addressing in the byte loads.
+    masm.ma_add(HeapReg, ptr);
+
+    MIRType mirType = mir->value()->type();
+
+    masm.memoryBarrier(mir->access().barrierAfter());
+
+    Register val = ToRegister(lir->valueHelper());
+    if (IsFloatingPointType(mirType)) {
+        masm.ma_vxfer(ToFloatRegister(lir->getOperand(LWasmUnalignedStore::ValueIndex)), val);
+    } else if (mirType == MIRType::Int64) {
+        Register64 input = ToRegister64(lir->getInt64Operand(LWasmUnalignedStoreI64::ValueIndex));
+        if (input.low != val)
+            masm.ma_mov(input.low, val);
+    }
+
+    unsigned byteSize = mir->access().byteSize();
+    masm.emitUnalignedStore(Min(byteSize, 4u), ptr, val);
+
+    if (byteSize > 4) {
+        // It's a double or an int64 load.
+        // Load the high 32 bits when counter == 4.
+        if (IsFloatingPointType(mirType)) {
+            FloatRegister fp = ToFloatRegister(lir->getOperand(LWasmUnalignedStore::ValueIndex));
+            MOZ_ASSERT(fp.isDouble());
+            ScratchRegisterScope scratch(masm);
+            masm.ma_vxfer(fp, scratch, val);
+        } else {
+            MOZ_ASSERT(mirType == MIRType::Int64);
+            masm.ma_mov(ToRegister64(lir->getInt64Operand(LWasmUnalignedStoreI64::ValueIndex)).high, val);
+        }
+        masm.emitUnalignedStore(4, ptr, val, /* offset */ 4);
+    }
+
+    masm.memoryBarrier(mir->access().barrierBefore());
+}
+
+void
+CodeGeneratorARM::visitWasmUnalignedStore(LWasmUnalignedStore* lir)
+{
+    emitWasmUnalignedStore(lir);
+}
+
+void
+CodeGeneratorARM::visitWasmUnalignedStoreI64(LWasmUnalignedStoreI64* lir)
+{
+    emitWasmUnalignedStore(lir);
+}
+
+void
+CodeGeneratorARM::visitAsmJSStoreHeap(LAsmJSStoreHeap* ins)
+{
+    const MAsmJSStoreHeap* mir = ins->mir();
+    MOZ_ASSERT(mir->offset() == 0);
+
+    const LAllocation* ptr = ins->ptr();
+
+    bool isSigned;
+    int size;
+    bool isFloat = false;
+    switch (mir->accessType()) {
+      case Scalar::Int8:
+      case Scalar::Uint8:   isSigned = false; size = 8; break;
+      case Scalar::Int16:
+      case Scalar::Uint16:  isSigned = false; size = 16; break;
+      case Scalar::Int32:
+      case Scalar::Uint32:  isSigned = true;  size = 32; break;
+      case Scalar::Float64: isFloat  = true;  size = 64; break;
+      case Scalar::Float32: isFloat = true;   size = 32; break;
+      default: MOZ_CRASH("unexpected array type");
+    }
+
+    if (ptr->isConstant()) {
+        MOZ_ASSERT(!mir->needsBoundsCheck());
+        int32_t ptrImm = ptr->toConstant()->toInt32();
+        MOZ_ASSERT(ptrImm >= 0);
+        if (isFloat) {
+            VFPRegister vd(ToFloatRegister(ins->value()));
+            Address addr(HeapReg, ptrImm);
+            if (size == 32)
+                masm.storeFloat32(vd, addr);
+            else
+                masm.storeDouble(vd, addr);
+        } else {
+            ScratchRegisterScope scratch(masm);
+            masm.ma_dataTransferN(IsStore, size, isSigned, HeapReg, Imm32(ptrImm),
+                                  ToRegister(ins->value()), scratch, Offset, Assembler::Always);
+        }
+    } else {
+        Register ptrReg = ToRegister(ptr);
+
+        Assembler::Condition cond = Assembler::Always;
+        if (mir->needsBoundsCheck()) {
+            BufferOffset cmp = masm.as_cmp(ptrReg, Imm8(0));
+            masm.append(wasm::BoundsCheck(cmp.getOffset()));
+
+            cond = Assembler::Below;
+        }
+
+        if (isFloat) {
+            ScratchRegisterScope scratch(masm);
+            FloatRegister value = ToFloatRegister(ins->value());
+            if (size == 32)
+                value = value.singleOverlay();
+
+            masm.ma_vstr(value, HeapReg, ptrReg, scratch, 0, Assembler::Below);
+        } else {
+            ScratchRegisterScope scratch(masm);
+            Register value = ToRegister(ins->value());
+            masm.ma_dataTransferN(IsStore, size, isSigned, HeapReg, ptrReg, value, scratch, Offset, cond);
+        }
+    }
+}
+
+void
+CodeGeneratorARM::visitAsmJSCompareExchangeHeap(LAsmJSCompareExchangeHeap* ins)
+{
+    MAsmJSCompareExchangeHeap* mir = ins->mir();
+    MOZ_ASSERT(mir->access().offset() == 0);
+
+    Scalar::Type vt = mir->access().type();
+    const LAllocation* ptr = ins->ptr();
+    Register ptrReg = ToRegister(ptr);
+    BaseIndex srcAddr(HeapReg, ptrReg, TimesOne);
+    MOZ_ASSERT(ins->addrTemp()->isBogusTemp());
+
+    Register oldval = ToRegister(ins->oldValue());
+    Register newval = ToRegister(ins->newValue());
+
+    masm.compareExchangeToTypedIntArray(vt == Scalar::Uint32 ? Scalar::Int32 : vt,
+                                        srcAddr, oldval, newval, InvalidReg,
+                                        ToAnyRegister(ins->output()));
+}
+
+void
+CodeGeneratorARM::visitAsmJSCompareExchangeCallout(LAsmJSCompareExchangeCallout* ins)
+{
+    const MAsmJSCompareExchangeHeap* mir = ins->mir();
+    MOZ_ASSERT(mir->access().offset() == 0);
+
+    Register ptr = ToRegister(ins->ptr());
+    Register oldval = ToRegister(ins->oldval());
+    Register newval = ToRegister(ins->newval());
+    Register tls = ToRegister(ins->tls());
+    Register instance = ToRegister(ins->getTemp(0));
+    Register viewType = ToRegister(ins->getTemp(1));
+
+    MOZ_ASSERT(ToRegister(ins->output()) == ReturnReg);
+
+    masm.loadPtr(Address(tls, offsetof(wasm::TlsData, instance)), instance);
+    masm.ma_mov(Imm32(mir->access().type()), viewType);
+
+    masm.setupAlignedABICall();
+    masm.passABIArg(instance);
+    masm.passABIArg(viewType);
+    masm.passABIArg(ptr);
+    masm.passABIArg(oldval);
+    masm.passABIArg(newval);
+    masm.callWithABI(wasm::SymbolicAddress::AtomicCmpXchg);
+}
+
+void
+CodeGeneratorARM::visitAsmJSAtomicExchangeHeap(LAsmJSAtomicExchangeHeap* ins)
+{
+    MAsmJSAtomicExchangeHeap* mir = ins->mir();
+    MOZ_ASSERT(mir->access().offset() == 0);
+
+    Scalar::Type vt = mir->access().type();
+    Register ptrReg = ToRegister(ins->ptr());
+    Register value = ToRegister(ins->value());
+    BaseIndex srcAddr(HeapReg, ptrReg, TimesOne);
+    MOZ_ASSERT(ins->addrTemp()->isBogusTemp());
+
+    masm.atomicExchangeToTypedIntArray(vt == Scalar::Uint32 ? Scalar::Int32 : vt,
+                                       srcAddr, value, InvalidReg, ToAnyRegister(ins->output()));
+}
+
+void
+CodeGeneratorARM::visitAsmJSAtomicExchangeCallout(LAsmJSAtomicExchangeCallout* ins)
+{
+    const MAsmJSAtomicExchangeHeap* mir = ins->mir();
+    MOZ_ASSERT(mir->access().offset() == 0);
+
+    Register ptr = ToRegister(ins->ptr());
+    Register value = ToRegister(ins->value());
+    Register tls = ToRegister(ins->tls());
+    Register instance = ToRegister(ins->getTemp(0));
+    Register viewType = ToRegister(ins->getTemp(1));
+
+    MOZ_ASSERT(ToRegister(ins->output()) == ReturnReg);
+
+    masm.loadPtr(Address(tls, offsetof(wasm::TlsData, instance)), instance);
+    masm.ma_mov(Imm32(mir->access().type()), viewType);
+
+    masm.setupAlignedABICall();
+    masm.passABIArg(instance);
+    masm.passABIArg(viewType);
+    masm.passABIArg(ptr);
+    masm.passABIArg(value);
+    masm.callWithABI(wasm::SymbolicAddress::AtomicXchg);
+}
+
+void
+CodeGeneratorARM::visitAsmJSAtomicBinopHeap(LAsmJSAtomicBinopHeap* ins)
+{
+    MAsmJSAtomicBinopHeap* mir = ins->mir();
+    MOZ_ASSERT(mir->access().offset() == 0);
+    MOZ_ASSERT(mir->hasUses());
+
+    Scalar::Type vt = mir->access().type();
+    Register ptrReg = ToRegister(ins->ptr());
+    Register flagTemp = ToRegister(ins->flagTemp());
+    const LAllocation* value = ins->value();
+    AtomicOp op = mir->operation();
+    MOZ_ASSERT(ins->addrTemp()->isBogusTemp());
+
+    BaseIndex srcAddr(HeapReg, ptrReg, TimesOne);
+
+    if (value->isConstant()) {
+        atomicBinopToTypedIntArray(op, vt == Scalar::Uint32 ? Scalar::Int32 : vt,
+                                   Imm32(ToInt32(value)), srcAddr, flagTemp, InvalidReg,
+                                   ToAnyRegister(ins->output()));
+    } else {
+        atomicBinopToTypedIntArray(op, vt == Scalar::Uint32 ? Scalar::Int32 : vt,
+                                   ToRegister(value), srcAddr, flagTemp, InvalidReg,
+                                   ToAnyRegister(ins->output()));
+    }
+}
+
+void
+CodeGeneratorARM::visitAsmJSAtomicBinopHeapForEffect(LAsmJSAtomicBinopHeapForEffect* ins)
+{
+    MAsmJSAtomicBinopHeap* mir = ins->mir();
+    MOZ_ASSERT(mir->access().offset() == 0);
+    MOZ_ASSERT(!mir->hasUses());
+
+    Scalar::Type vt = mir->access().type();
+    Register ptrReg = ToRegister(ins->ptr());
+    Register flagTemp = ToRegister(ins->flagTemp());
+    const LAllocation* value = ins->value();
+    AtomicOp op = mir->operation();
+    MOZ_ASSERT(ins->addrTemp()->isBogusTemp());
+
+    BaseIndex srcAddr(HeapReg, ptrReg, TimesOne);
+
+    if (value->isConstant())
+        atomicBinopToTypedIntArray(op, vt, Imm32(ToInt32(value)), srcAddr, flagTemp);
+    else
+        atomicBinopToTypedIntArray(op, vt, ToRegister(value), srcAddr, flagTemp);
+}
+
+void
+CodeGeneratorARM::visitAsmJSAtomicBinopCallout(LAsmJSAtomicBinopCallout* ins)
+{
+    const MAsmJSAtomicBinopHeap* mir = ins->mir();
+    MOZ_ASSERT(mir->access().offset() == 0);
+
+    Register ptr = ToRegister(ins->ptr());
+    Register value = ToRegister(ins->value());
+    Register tls = ToRegister(ins->tls());
+    Register instance = ToRegister(ins->getTemp(0));
+    Register viewType = ToRegister(ins->getTemp(1));
+
+    masm.loadPtr(Address(tls, offsetof(wasm::TlsData, instance)), instance);
+    masm.move32(Imm32(mir->access().type()), viewType);
+
+    masm.setupAlignedABICall();
+    masm.passABIArg(instance);
+    masm.passABIArg(viewType);
+    masm.passABIArg(ptr);
+    masm.passABIArg(value);
+
+    switch (mir->operation()) {
+      case AtomicFetchAddOp:
+        masm.callWithABI(wasm::SymbolicAddress::AtomicFetchAdd);
+        break;
+      case AtomicFetchSubOp:
+        masm.callWithABI(wasm::SymbolicAddress::AtomicFetchSub);
+        break;
+      case AtomicFetchAndOp:
+        masm.callWithABI(wasm::SymbolicAddress::AtomicFetchAnd);
+        break;
+      case AtomicFetchOrOp:
+        masm.callWithABI(wasm::SymbolicAddress::AtomicFetchOr);
+        break;
+      case AtomicFetchXorOp:
+        masm.callWithABI(wasm::SymbolicAddress::AtomicFetchXor);
+        break;
+      default:
+        MOZ_CRASH("Unknown op");
+    }
+}
+
+void
+CodeGeneratorARM::visitWasmStackArg(LWasmStackArg* ins)
+{
+    const MWasmStackArg* mir = ins->mir();
+    Address dst(StackPointer, mir->spOffset());
+    ScratchRegisterScope scratch(masm);
+    SecondScratchRegisterScope scratch2(masm);
+
+    if (ins->arg()->isConstant()) {
+        masm.ma_mov(Imm32(ToInt32(ins->arg())), scratch);
+        masm.ma_str(scratch, dst, scratch2);
+    } else {
+        if (ins->arg()->isGeneralReg())
+            masm.ma_str(ToRegister(ins->arg()), dst, scratch);
+        else
+            masm.ma_vstr(ToFloatRegister(ins->arg()), dst, scratch);
+    }
+}
+
+void
+CodeGeneratorARM::visitUDiv(LUDiv* ins)
+{
+    Register lhs = ToRegister(ins->lhs());
+    Register rhs = ToRegister(ins->rhs());
+    Register output = ToRegister(ins->output());
+
+    Label done;
+    generateUDivModZeroCheck(rhs, output, &done, ins->snapshot(), ins->mir());
+
+    masm.ma_udiv(lhs, rhs, output);
+
+    // Check for large unsigned result - represent as double.
+    if (!ins->mir()->isTruncated()) {
+        MOZ_ASSERT(ins->mir()->fallible());
+        masm.as_cmp(output, Imm8(0));
+        bailoutIf(Assembler::LessThan, ins->snapshot());
+    }
+
+    // Check for non-zero remainder if not truncating to int.
+    if (!ins->mir()->canTruncateRemainder()) {
+        MOZ_ASSERT(ins->mir()->fallible());
+        {
+            ScratchRegisterScope scratch(masm);
+            masm.ma_mul(rhs, output, scratch);
+            masm.ma_cmp(scratch, lhs);
+        }
+        bailoutIf(Assembler::NotEqual, ins->snapshot());
+    }
+
+    if (done.used())
+        masm.bind(&done);
+}
+
+void
+CodeGeneratorARM::visitUMod(LUMod* ins)
+{
+    Register lhs = ToRegister(ins->lhs());
+    Register rhs = ToRegister(ins->rhs());
+    Register output = ToRegister(ins->output());
+
+    Label done;
+    generateUDivModZeroCheck(rhs, output, &done, ins->snapshot(), ins->mir());
+
+    {
+        ScratchRegisterScope scratch(masm);
+        masm.ma_umod(lhs, rhs, output, scratch);
+    }
+
+    // Check for large unsigned result - represent as double.
+    if (!ins->mir()->isTruncated()) {
+        MOZ_ASSERT(ins->mir()->fallible());
+        masm.as_cmp(output, Imm8(0));
+        bailoutIf(Assembler::LessThan, ins->snapshot());
+    }
+
+    if (done.used())
+        masm.bind(&done);
+}
+
+template<class T>
+void
+CodeGeneratorARM::generateUDivModZeroCheck(Register rhs, Register output, Label* done,
+                                           LSnapshot* snapshot, T* mir)
+{
+    if (!mir)
+        return;
+    if (mir->canBeDivideByZero()) {
+        masm.as_cmp(rhs, Imm8(0));
+        if (mir->isTruncated()) {
+            if (mir->trapOnError()) {
+                masm.ma_b(trap(mir, wasm::Trap::IntegerDivideByZero), Assembler::Equal);
+            } else {
+                Label skip;
+                masm.ma_b(&skip, Assembler::NotEqual);
+                // Infinity|0 == 0
+                masm.ma_mov(Imm32(0), output);
+                masm.ma_b(done);
+                masm.bind(&skip);
+            }
+        } else {
+            // Bailout for divide by zero
+            MOZ_ASSERT(mir->fallible());
+            bailoutIf(Assembler::Equal, snapshot);
+        }
+    }
+}
+
+void
+CodeGeneratorARM::visitSoftUDivOrMod(LSoftUDivOrMod* ins)
+{
+    Register lhs = ToRegister(ins->lhs());
+    Register rhs = ToRegister(ins->rhs());
+    Register output = ToRegister(ins->output());
+
+    MOZ_ASSERT(lhs == r0);
+    MOZ_ASSERT(rhs == r1);
+    MOZ_ASSERT(ins->mirRaw()->isDiv() || ins->mirRaw()->isMod());
+    MOZ_ASSERT_IF(ins->mirRaw()->isDiv(), output == r0);
+    MOZ_ASSERT_IF(ins->mirRaw()->isMod(), output == r1);
+
+    Label done;
+    MDiv* div = ins->mir()->isDiv() ? ins->mir()->toDiv() : nullptr;
+    MMod* mod = !div ? ins->mir()->toMod() : nullptr;
+
+    generateUDivModZeroCheck(rhs, output, &done, ins->snapshot(), div);
+    generateUDivModZeroCheck(rhs, output, &done, ins->snapshot(), mod);
+
+    masm.setupAlignedABICall();
+    masm.passABIArg(lhs);
+    masm.passABIArg(rhs);
+    if (gen->compilingWasm())
+        masm.callWithABI(wasm::SymbolicAddress::aeabi_uidivmod);
+    else
+        masm.callWithABI(JS_FUNC_TO_DATA_PTR(void*, __aeabi_uidivmod));
+
+    // uidivmod returns the quotient in r0, and the remainder in r1.
+    if (div && !div->canTruncateRemainder()) {
+        MOZ_ASSERT(div->fallible());
+        masm.as_cmp(r1, Imm8(0));
+        bailoutIf(Assembler::NonZero, ins->snapshot());
+    }
+
+    // Bailout for big unsigned results
+    if ((div && !div->isTruncated()) || (mod && !mod->isTruncated())) {
+        DebugOnly<bool> isFallible = (div && div->fallible()) || (mod && mod->fallible());
+        MOZ_ASSERT(isFallible);
+        masm.as_cmp(output, Imm8(0));
+        bailoutIf(Assembler::LessThan, ins->snapshot());
+    }
+
+    masm.bind(&done);
+}
+
+void
+CodeGeneratorARM::visitEffectiveAddress(LEffectiveAddress* ins)
+{
+    const MEffectiveAddress* mir = ins->mir();
+    Register base = ToRegister(ins->base());
+    Register index = ToRegister(ins->index());
+    Register output = ToRegister(ins->output());
+
+    ScratchRegisterScope scratch(masm);
+
+    masm.as_add(output, base, lsl(index, mir->scale()));
+    masm.ma_add(Imm32(mir->displacement()), output, scratch);
+}
+
+void
+CodeGeneratorARM::visitWasmLoadGlobalVar(LWasmLoadGlobalVar* ins)
+{
+    const MWasmLoadGlobalVar* mir = ins->mir();
+    unsigned addr = mir->globalDataOffset() - WasmGlobalRegBias;
+
+    ScratchRegisterScope scratch(masm);
+
+    if (mir->type() == MIRType::Int32) {
+        masm.ma_dtr(IsLoad, GlobalReg, Imm32(addr), ToRegister(ins->output()), scratch);
+    } else if (mir->type() == MIRType::Float32) {
+        VFPRegister vd(ToFloatRegister(ins->output()));
+        masm.ma_vldr(Address(GlobalReg, addr), vd.singleOverlay(), scratch);
+    } else {
+        MOZ_ASSERT(mir->type() == MIRType::Double);
+        masm.ma_vldr(Address(GlobalReg, addr), ToFloatRegister(ins->output()), scratch);
+    }
+}
+
+void
+CodeGeneratorARM::visitWasmLoadGlobalVarI64(LWasmLoadGlobalVarI64* ins)
+{
+    const MWasmLoadGlobalVar* mir = ins->mir();
+    unsigned addr = mir->globalDataOffset() - WasmGlobalRegBias;
+    MOZ_ASSERT(mir->type() == MIRType::Int64);
+    Register64 output = ToOutRegister64(ins);
+
+    ScratchRegisterScope scratch(masm);
+    masm.ma_dtr(IsLoad, GlobalReg, Imm32(addr + INT64LOW_OFFSET), output.low, scratch);
+    masm.ma_dtr(IsLoad, GlobalReg, Imm32(addr + INT64HIGH_OFFSET), output.high, scratch);
+}
+
+void
+CodeGeneratorARM::visitWasmStoreGlobalVar(LWasmStoreGlobalVar* ins)
+{
+    const MWasmStoreGlobalVar* mir = ins->mir();
+    MIRType type = mir->value()->type();
+
+    ScratchRegisterScope scratch(masm);
+
+    unsigned addr = mir->globalDataOffset() - WasmGlobalRegBias;
+    if (type == MIRType::Int32) {
+        masm.ma_dtr(IsStore, GlobalReg, Imm32(addr), ToRegister(ins->value()), scratch);
+    } else if (type == MIRType::Float32) {
+        VFPRegister vd(ToFloatRegister(ins->value()));
+        masm.ma_vstr(vd.singleOverlay(), Address(GlobalReg, addr), scratch);
+    } else {
+        MOZ_ASSERT(type == MIRType::Double);
+        masm.ma_vstr(ToFloatRegister(ins->value()), Address(GlobalReg, addr), scratch);
+    }
+}
+
+void
+CodeGeneratorARM::visitWasmStoreGlobalVarI64(LWasmStoreGlobalVarI64* ins)
+{
+    const MWasmStoreGlobalVar* mir = ins->mir();
+    unsigned addr = mir->globalDataOffset() - WasmGlobalRegBias;
+    MOZ_ASSERT (mir->value()->type() == MIRType::Int64);
+    Register64 input = ToRegister64(ins->value());
+
+    ScratchRegisterScope scratch(masm);
+    masm.ma_dtr(IsStore, GlobalReg, Imm32(addr + INT64LOW_OFFSET), input.low, scratch);
+    masm.ma_dtr(IsStore, GlobalReg, Imm32(addr + INT64HIGH_OFFSET), input.high, scratch);
+}
+
+void
+CodeGeneratorARM::visitNegI(LNegI* ins)
+{
+    Register input = ToRegister(ins->input());
+    masm.ma_neg(input, ToRegister(ins->output()));
+}
+
+void
+CodeGeneratorARM::visitNegD(LNegD* ins)
+{
+    FloatRegister input = ToFloatRegister(ins->input());
+    masm.ma_vneg(input, ToFloatRegister(ins->output()));
+}
+
+void
+CodeGeneratorARM::visitNegF(LNegF* ins)
+{
+    FloatRegister input = ToFloatRegister(ins->input());
+    masm.ma_vneg_f32(input, ToFloatRegister(ins->output()));
+}
+
+void
+CodeGeneratorARM::visitMemoryBarrier(LMemoryBarrier* ins)
+{
+    masm.memoryBarrier(ins->type());
+}
+
+void
+CodeGeneratorARM::setReturnDoubleRegs(LiveRegisterSet* regs)
+{
+    MOZ_ASSERT(ReturnFloat32Reg.code_ == FloatRegisters::s0);
+    MOZ_ASSERT(ReturnDoubleReg.code_ == FloatRegisters::s0);
+    FloatRegister s1 = {FloatRegisters::s1, VFPRegister::Single};
+    regs->add(ReturnFloat32Reg);
+    regs->add(s1);
+    regs->add(ReturnDoubleReg);
+}
+
+void
+CodeGeneratorARM::visitWasmTruncateToInt32(LWasmTruncateToInt32* lir)
+{
+    auto input = ToFloatRegister(lir->input());
+    auto output = ToRegister(lir->output());
+
+    MWasmTruncateToInt32* mir = lir->mir();
+    MIRType fromType = mir->input()->type();
+
+    auto* ool = new(alloc()) OutOfLineWasmTruncateCheck(mir, input);
+    addOutOfLineCode(ool, mir);
+    masm.wasmTruncateToInt32(input, output, fromType, mir->isUnsigned(), ool->entry());
+    masm.bind(ool->rejoin());
+}
+
+void
+CodeGeneratorARM::visitWasmTruncateToInt64(LWasmTruncateToInt64* lir)
+{
+    FloatRegister input = ToFloatRegister(lir->input());
+    FloatRegister inputDouble = input;
+    Register64 output = ToOutRegister64(lir);
+
+    MWasmTruncateToInt64* mir = lir->mir();
+    MIRType fromType = mir->input()->type();
+
+    auto* ool = new(alloc()) OutOfLineWasmTruncateCheck(mir, input);
+    addOutOfLineCode(ool, mir);
+
+    ScratchDoubleScope scratchScope(masm);
+    if (fromType == MIRType::Float32) {
+        inputDouble = ScratchDoubleReg;
+        masm.convertFloat32ToDouble(input, inputDouble);
+    }
+
+    masm.Push(input);
+
+    masm.setupUnalignedABICall(output.high);
+    masm.passABIArg(inputDouble, MoveOp::DOUBLE);
+    if (lir->mir()->isUnsigned())
+        masm.callWithABI(wasm::SymbolicAddress::TruncateDoubleToUint64);
+    else
+        masm.callWithABI(wasm::SymbolicAddress::TruncateDoubleToInt64);
+
+    masm.Pop(input);
+
+    ScratchRegisterScope scratch(masm);
+    masm.ma_cmp(output.high, Imm32(0x80000000), scratch);
+    masm.as_cmp(output.low, Imm8(0x00000000), Assembler::Equal);
+    masm.ma_b(ool->entry(), Assembler::Equal);
+
+    masm.bind(ool->rejoin());
+
+    MOZ_ASSERT(ReturnReg64 == output);
+}
+
+void
+CodeGeneratorARM::visitOutOfLineWasmTruncateCheck(OutOfLineWasmTruncateCheck* ool)
+{
+    masm.outOfLineWasmTruncateToIntCheck(ool->input(), ool->fromType(), ool->toType(),
+                                         ool->isUnsigned(), ool->rejoin(),
+                                         ool->trapOffset());
+}
+
+void
+CodeGeneratorARM::visitInt64ToFloatingPointCall(LInt64ToFloatingPointCall* lir)
+{
+    Register64 input = ToRegister64(lir->getInt64Operand(0));
+    FloatRegister output = ToFloatRegister(lir->output());
+
+    MInt64ToFloatingPoint* mir = lir->mir();
+    MIRType toType = mir->type();
+
+    // We are free to clobber all registers, since this is a call instruction.
+    AllocatableGeneralRegisterSet regs(GeneralRegisterSet::All());
+    regs.take(input.low);
+    regs.take(input.high);
+    Register temp = regs.takeAny();
+
+    masm.setupUnalignedABICall(temp);
+    masm.passABIArg(input.high);
+    masm.passABIArg(input.low);
+    if (lir->mir()->isUnsigned())
+        masm.callWithABI(wasm::SymbolicAddress::Uint64ToFloatingPoint, MoveOp::DOUBLE);
+    else
+        masm.callWithABI(wasm::SymbolicAddress::Int64ToFloatingPoint, MoveOp::DOUBLE);
+
+    MOZ_ASSERT_IF(toType == MIRType::Double, output == ReturnDoubleReg);
+    if (toType == MIRType::Float32) {
+        MOZ_ASSERT(output == ReturnFloat32Reg);
+        masm.convertDoubleToFloat32(ReturnDoubleReg, output);
+    }
+}
+
+void
+CodeGeneratorARM::visitCopySignF(LCopySignF* ins)
+{
+    FloatRegister lhs = ToFloatRegister(ins->getOperand(0));
+    FloatRegister rhs = ToFloatRegister(ins->getOperand(1));
+    FloatRegister output = ToFloatRegister(ins->getDef(0));
+
+    Register lhsi = ToRegister(ins->getTemp(0));
+    Register rhsi = ToRegister(ins->getTemp(1));
+
+    masm.ma_vxfer(lhs, lhsi);
+    masm.ma_vxfer(rhs, rhsi);
+
+    ScratchRegisterScope scratch(masm);
+
+    // Clear lhs's sign.
+    masm.ma_and(Imm32(INT32_MAX), lhsi, lhsi, scratch);
+
+    // Keep rhs's sign.
+    masm.ma_and(Imm32(INT32_MIN), rhsi, rhsi, scratch);
+
+    // Combine.
+    masm.ma_orr(lhsi, rhsi, rhsi);
+
+    masm.ma_vxfer(rhsi, output);
+}
+
+void
+CodeGeneratorARM::visitCopySignD(LCopySignD* ins)
+{
+    FloatRegister lhs = ToFloatRegister(ins->getOperand(0));
+    FloatRegister rhs = ToFloatRegister(ins->getOperand(1));
+    FloatRegister output = ToFloatRegister(ins->getDef(0));
+
+    Register lhsi = ToRegister(ins->getTemp(0));
+    Register rhsi = ToRegister(ins->getTemp(1));
+
+    // Manipulate high words of double inputs.
+    masm.as_vxfer(lhsi, InvalidReg, lhs, Assembler::FloatToCore, Assembler::Always, 1);
+    masm.as_vxfer(rhsi, InvalidReg, rhs, Assembler::FloatToCore, Assembler::Always, 1);
+
+    ScratchRegisterScope scratch(masm);
+
+    // Clear lhs's sign.
+    masm.ma_and(Imm32(INT32_MAX), lhsi, lhsi, scratch);
+
+    // Keep rhs's sign.
+    masm.ma_and(Imm32(INT32_MIN), rhsi, rhsi, scratch);
+
+    // Combine.
+    masm.ma_orr(lhsi, rhsi, rhsi);
+
+    // Reconstruct the output.
+    masm.as_vxfer(lhsi, InvalidReg, lhs, Assembler::FloatToCore, Assembler::Always, 0);
+    masm.ma_vxfer(lhsi, rhsi, output);
+}
+
+void
+CodeGeneratorARM::visitWrapInt64ToInt32(LWrapInt64ToInt32* lir)
+{
+    const LInt64Allocation& input = lir->getInt64Operand(0);
+    Register output = ToRegister(lir->output());
+
+    if (lir->mir()->bottomHalf())
+        masm.move32(ToRegister(input.low()), output);
+    else
+        masm.move32(ToRegister(input.high()), output);
+}
+
+void
+CodeGeneratorARM::visitExtendInt32ToInt64(LExtendInt32ToInt64* lir)
+{
+    Register64 output = ToOutRegister64(lir);
+    MOZ_ASSERT(ToRegister(lir->input()) == output.low);
+
+    if (lir->mir()->isUnsigned())
+        masm.ma_mov(Imm32(0), output.high);
+    else
+        masm.ma_asr(Imm32(31), output.low, output.high);
+}
+
+void
+CodeGeneratorARM::visitDivOrModI64(LDivOrModI64* lir)
+{
+    Register64 lhs = ToRegister64(lir->getInt64Operand(LDivOrModI64::Lhs));
+    Register64 rhs = ToRegister64(lir->getInt64Operand(LDivOrModI64::Rhs));
+    Register64 output = ToOutRegister64(lir);
+
+    MOZ_ASSERT(output == ReturnReg64);
+
+    // All inputs are useAtStart for a call instruction. As a result we cannot
+    // ask for a non-aliasing temp. Using the following to get such a temp.
+    AllocatableGeneralRegisterSet regs(GeneralRegisterSet::All());
+    regs.take(lhs.low);
+    regs.take(lhs.high);
+    if (lhs != rhs) {
+        regs.take(rhs.low);
+        regs.take(rhs.high);
+    }
+    Register temp = regs.takeAny();
+
+    Label done;
+
+    // Handle divide by zero.
+    if (lir->canBeDivideByZero())
+        masm.branchTest64(Assembler::Zero, rhs, rhs, temp, trap(lir, wasm::Trap::IntegerDivideByZero));
+
+    // Handle an integer overflow exception from INT64_MIN / -1.
+    if (lir->canBeNegativeOverflow()) {
+        Label notmin;
+        masm.branch64(Assembler::NotEqual, lhs, Imm64(INT64_MIN), &notmin);
+        masm.branch64(Assembler::NotEqual, rhs, Imm64(-1), &notmin);
+        if (lir->mir()->isMod())
+            masm.xor64(output, output);
+        else
+            masm.jump(trap(lir, wasm::Trap::IntegerOverflow));
+        masm.jump(&done);
+        masm.bind(&notmin);
+    }
+
+    masm.setupUnalignedABICall(temp);
+    masm.passABIArg(lhs.high);
+    masm.passABIArg(lhs.low);
+    masm.passABIArg(rhs.high);
+    masm.passABIArg(rhs.low);
+
+    MOZ_ASSERT(gen->compilingWasm());
+    if (lir->mir()->isMod())
+        masm.callWithABI(wasm::SymbolicAddress::ModI64);
+    else
+        masm.callWithABI(wasm::SymbolicAddress::DivI64);
+
+    MOZ_ASSERT(ReturnReg64 == output);
+
+    masm.bind(&done);
+}
+
+void
+CodeGeneratorARM::visitUDivOrModI64(LUDivOrModI64* lir)
+{
+    Register64 lhs = ToRegister64(lir->getInt64Operand(LDivOrModI64::Lhs));
+    Register64 rhs = ToRegister64(lir->getInt64Operand(LDivOrModI64::Rhs));
+
+    MOZ_ASSERT(ToOutRegister64(lir) == ReturnReg64);
+
+    // All inputs are useAtStart for a call instruction. As a result we cannot
+    // ask for a non-aliasing temp. Using the following to get such a temp.
+    AllocatableGeneralRegisterSet regs(GeneralRegisterSet::All());
+    regs.take(lhs.low);
+    regs.take(lhs.high);
+    if (lhs != rhs) {
+        regs.take(rhs.low);
+        regs.take(rhs.high);
+    }
+    Register temp = regs.takeAny();
+
+    // Prevent divide by zero.
+    if (lir->canBeDivideByZero())
+        masm.branchTest64(Assembler::Zero, rhs, rhs, temp, trap(lir, wasm::Trap::IntegerDivideByZero));
+
+    masm.setupUnalignedABICall(temp);
+    masm.passABIArg(lhs.high);
+    masm.passABIArg(lhs.low);
+    masm.passABIArg(rhs.high);
+    masm.passABIArg(rhs.low);
+
+    MOZ_ASSERT(gen->compilingWasm());
+    if (lir->mir()->isMod())
+        masm.callWithABI(wasm::SymbolicAddress::UModI64);
+    else
+        masm.callWithABI(wasm::SymbolicAddress::UDivI64);
+}
+
+void
+CodeGeneratorARM::visitCompareI64(LCompareI64* lir)
+{
+    MCompare* mir = lir->mir();
+    MOZ_ASSERT(mir->compareType() == MCompare::Compare_Int64 ||
+               mir->compareType() == MCompare::Compare_UInt64);
+
+    const LInt64Allocation lhs = lir->getInt64Operand(LCompareI64::Lhs);
+    const LInt64Allocation rhs = lir->getInt64Operand(LCompareI64::Rhs);
+    Register64 lhsRegs = ToRegister64(lhs);
+    Register output = ToRegister(lir->output());
+
+    bool isSigned = mir->compareType() == MCompare::Compare_Int64;
+    Assembler::Condition condition = JSOpToCondition(lir->jsop(), isSigned);
+    Label done;
+
+    masm.move32(Imm32(1), output);
+
+    if (IsConstant(rhs)) {
+        Imm64 imm = Imm64(ToInt64(rhs));
+        masm.branch64(condition, lhsRegs, imm, &done);
+    } else {
+        Register64 rhsRegs = ToRegister64(rhs);
+        masm.branch64(condition, lhsRegs, rhsRegs, &done);
+    }
+
+    masm.move32(Imm32(0), output);
+    masm.bind(&done);
+}
+
+void
+CodeGeneratorARM::visitCompareI64AndBranch(LCompareI64AndBranch* lir)
+{
+    MCompare* mir = lir->cmpMir();
+    MOZ_ASSERT(mir->compareType() == MCompare::Compare_Int64 ||
+               mir->compareType() == MCompare::Compare_UInt64);
+
+    const LInt64Allocation lhs = lir->getInt64Operand(LCompareI64::Lhs);
+    const LInt64Allocation rhs = lir->getInt64Operand(LCompareI64::Rhs);
+    Register64 lhsRegs = ToRegister64(lhs);
+
+    bool isSigned = mir->compareType() == MCompare::Compare_Int64;
+    Assembler::Condition condition = JSOpToCondition(lir->jsop(), isSigned);
+
+    Label* trueLabel = getJumpLabelForBranch(lir->ifTrue());
+    Label* falseLabel = getJumpLabelForBranch(lir->ifFalse());
+
+    if (isNextBlock(lir->ifFalse()->lir())) {
+        falseLabel = nullptr;
+    } else if (isNextBlock(lir->ifTrue()->lir())) {
+        condition = Assembler::InvertCondition(condition);
+        trueLabel = falseLabel;
+        falseLabel = nullptr;
+    }
+
+    if (IsConstant(rhs)) {
+        Imm64 imm = Imm64(ToInt64(rhs));
+        masm.branch64(condition, lhsRegs, imm, trueLabel, falseLabel);
+    } else {
+        Register64 rhsRegs = ToRegister64(rhs);
+        masm.branch64(condition, lhsRegs, rhsRegs, trueLabel, falseLabel);
+    }
+}
+
+void
+CodeGeneratorARM::visitShiftI64(LShiftI64* lir)
+{
+    const LInt64Allocation lhs = lir->getInt64Operand(LShiftI64::Lhs);
+    LAllocation* rhs = lir->getOperand(LShiftI64::Rhs);
+
+    MOZ_ASSERT(ToOutRegister64(lir) == ToRegister64(lhs));
+
+    if (rhs->isConstant()) {
+        int32_t shift = int32_t(rhs->toConstant()->toInt64() & 0x3F);
+        switch (lir->bitop()) {
+          case JSOP_LSH:
+            if (shift)
+                masm.lshift64(Imm32(shift), ToRegister64(lhs));
+            break;
+          case JSOP_RSH:
+            if (shift)
+                masm.rshift64Arithmetic(Imm32(shift), ToRegister64(lhs));
+            break;
+          case JSOP_URSH:
+            if (shift)
+                masm.rshift64(Imm32(shift), ToRegister64(lhs));
+            break;
+          default:
+            MOZ_CRASH("Unexpected shift op");
+        }
+        return;
+    }
+
+    switch (lir->bitop()) {
+      case JSOP_LSH:
+        masm.lshift64(ToRegister(rhs), ToRegister64(lhs));
+        break;
+      case JSOP_RSH:
+        masm.rshift64Arithmetic(ToRegister(rhs), ToRegister64(lhs));
+        break;
+      case JSOP_URSH:
+        masm.rshift64(ToRegister(rhs), ToRegister64(lhs));
+        break;
+      default:
+        MOZ_CRASH("Unexpected shift op");
+    }
+}
+
+void
+CodeGeneratorARM::visitBitOpI64(LBitOpI64* lir)
+{
+    const LInt64Allocation lhs = lir->getInt64Operand(LBitOpI64::Lhs);
+    const LInt64Allocation rhs = lir->getInt64Operand(LBitOpI64::Rhs);
+
+    MOZ_ASSERT(ToOutRegister64(lir) == ToRegister64(lhs));
+
+    switch (lir->bitop()) {
+      case JSOP_BITOR:
+        if (IsConstant(rhs))
+            masm.or64(Imm64(ToInt64(rhs)), ToRegister64(lhs));
+        else
+            masm.or64(ToOperandOrRegister64(rhs), ToRegister64(lhs));
+        break;
+      case JSOP_BITXOR:
+        if (IsConstant(rhs))
+            masm.xor64(Imm64(ToInt64(rhs)), ToRegister64(lhs));
+        else
+            masm.xor64(ToOperandOrRegister64(rhs), ToRegister64(lhs));
+        break;
+      case JSOP_BITAND:
+        if (IsConstant(rhs))
+            masm.and64(Imm64(ToInt64(rhs)), ToRegister64(lhs));
+        else
+            masm.and64(ToOperandOrRegister64(rhs), ToRegister64(lhs));
+        break;
+      default:
+        MOZ_CRASH("unexpected binary opcode");
+    }
+}
+
+void
+CodeGeneratorARM::visitRotateI64(LRotateI64* lir)
+{
+    MRotate* mir = lir->mir();
+    LAllocation* count = lir->count();
+
+    Register64 input = ToRegister64(lir->input());
+    Register64 output = ToOutRegister64(lir);
+    Register temp = ToTempRegisterOrInvalid(lir->temp());
+
+    if (count->isConstant()) {
+        int32_t c = int32_t(count->toConstant()->toInt64() & 0x3F);
+        if (!c) {
+            masm.move64(input, output);
+            return;
+        }
+        if (mir->isLeftRotate())
+            masm.rotateLeft64(Imm32(c), input, output, temp);
+        else
+            masm.rotateRight64(Imm32(c), input, output, temp);
+    } else {
+        if (mir->isLeftRotate())
+            masm.rotateLeft64(ToRegister(count), input, output, temp);
+        else
+            masm.rotateRight64(ToRegister(count), input, output, temp);
+    }
+}
+
+void
+CodeGeneratorARM::visitWasmStackArgI64(LWasmStackArgI64* ins)
+{
+    const MWasmStackArg* mir = ins->mir();
+    Address dst(StackPointer, mir->spOffset());
+    if (IsConstant(ins->arg()))
+        masm.store64(Imm64(ToInt64(ins->arg())), dst);
+    else
+        masm.store64(ToRegister64(ins->arg()), dst);
+}
+
+void
+CodeGeneratorARM::visitWasmSelectI64(LWasmSelectI64* lir)
+{
+    Register cond = ToRegister(lir->condExpr());
+    const LInt64Allocation falseExpr = lir->falseExpr();
+
+    Register64 out = ToOutRegister64(lir);
+    MOZ_ASSERT(ToRegister64(lir->trueExpr()) == out, "true expr is reused for input");
+
+    masm.as_cmp(cond, Imm8(0));
+    if (falseExpr.low().isRegister()) {
+        masm.ma_mov(ToRegister(falseExpr.low()), out.low, LeaveCC, Assembler::Equal);
+        masm.ma_mov(ToRegister(falseExpr.high()), out.high, LeaveCC, Assembler::Equal);
+    } else {
+        ScratchRegisterScope scratch(masm);
+        masm.ma_ldr(ToAddress(falseExpr.low()), out.low, scratch, Offset, Assembler::Equal);
+        masm.ma_ldr(ToAddress(falseExpr.high()), out.high, scratch, Offset, Assembler::Equal);
+    }
+}
+
+void
+CodeGeneratorARM::visitWasmReinterpretFromI64(LWasmReinterpretFromI64* lir)
+{
+    MOZ_ASSERT(lir->mir()->type() == MIRType::Double);
+    MOZ_ASSERT(lir->mir()->input()->type() == MIRType::Int64);
+    Register64 input = ToRegister64(lir->getInt64Operand(0));
+    FloatRegister output = ToFloatRegister(lir->output());
+
+    masm.ma_vxfer(input.low, input.high, output);
+}
+
+void
+CodeGeneratorARM::visitWasmReinterpretToI64(LWasmReinterpretToI64* lir)
+{
+    MOZ_ASSERT(lir->mir()->type() == MIRType::Int64);
+    MOZ_ASSERT(lir->mir()->input()->type() == MIRType::Double);
+    FloatRegister input = ToFloatRegister(lir->getOperand(0));
+    Register64 output = ToOutRegister64(lir);
+
+    masm.ma_vxfer(input, output.low, output.high);
+}
+
+void
+CodeGeneratorARM::visitPopcntI64(LPopcntI64* lir)
+{
+    Register64 input = ToRegister64(lir->getInt64Operand(0));
+    Register64 output = ToOutRegister64(lir);
+    Register temp = ToRegister(lir->getTemp(0));
+
+    masm.popcnt64(input, output, temp);
+}
+
+void
+CodeGeneratorARM::visitClzI64(LClzI64* lir)
+{
+    Register64 input = ToRegister64(lir->getInt64Operand(0));
+    Register64 output = ToOutRegister64(lir);
+
+    masm.clz64(input, output.low);
+    masm.move32(Imm32(0), output.high);
+}
+
+void
+CodeGeneratorARM::visitCtzI64(LCtzI64* lir)
+{
+    Register64 input = ToRegister64(lir->getInt64Operand(0));
+    Register64 output = ToOutRegister64(lir);
+
+    masm.ctz64(input, output.low);
+    masm.move32(Imm32(0), output.high);
+}
+
+void
+CodeGeneratorARM::visitTestI64AndBranch(LTestI64AndBranch* lir)
+{
+    Register64 input = ToRegister64(lir->getInt64Operand(0));
+
+    masm.as_cmp(input.high, Imm8(0));
+    jumpToBlock(lir->ifTrue(), Assembler::NonZero);
+    masm.as_cmp(input.low, Imm8(0));
+    emitBranch(Assembler::NonZero, lir->ifTrue(), lir->ifFalse());
+}
diff --git a/js/src/jit/arm/CodeGenerator-arm.h b/js/src/jit/arm/CodeGenerator-arm.h
new file mode 100644
index 0000000000..e617f50ebf
--- /dev/null
+++ b/js/src/jit/arm/CodeGenerator-arm.h
@@ -0,0 +1,336 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef jit_arm_CodeGenerator_arm_h
+#define jit_arm_CodeGenerator_arm_h
+
+#include "jit/arm/Assembler-arm.h"
+#include "jit/shared/CodeGenerator-shared.h"
+
+namespace js {
+namespace jit {
+
+class OutOfLineBailout;
+class OutOfLineTableSwitch;
+
+class CodeGeneratorARM : public CodeGeneratorShared
+{
+    friend class MoveResolverARM;
+
+    CodeGeneratorARM* thisFromCtor() {return this;}
+
+  protected:
+    NonAssertingLabel deoptLabel_;
+
+    MoveOperand toMoveOperand(LAllocation a) const;
+
+    void bailoutIf(Assembler::Condition condition, LSnapshot* snapshot);
+    void bailoutFrom(Label* label, LSnapshot* snapshot);
+    void bailout(LSnapshot* snapshot);
+
+    template <typename T1, typename T2>
+    void bailoutCmpPtr(Assembler::Condition c, T1 lhs, T2 rhs, LSnapshot* snapshot) {
+        masm.cmpPtr(lhs, rhs);
+        bailoutIf(c, snapshot);
+    }
+    void bailoutTestPtr(Assembler::Condition c, Register lhs, Register rhs, LSnapshot* snapshot) {
+        masm.testPtr(lhs, rhs);
+        bailoutIf(c, snapshot);
+    }
+    template <typename T1, typename T2>
+    void bailoutCmp32(Assembler::Condition c, T1 lhs, T2 rhs, LSnapshot* snapshot) {
+        masm.cmp32(lhs, rhs);
+        bailoutIf(c, snapshot);
+    }
+    template <typename T1, typename T2>
+    void bailoutTest32(Assembler::Condition c, T1 lhs, T2 rhs, LSnapshot* snapshot) {
+        masm.test32(lhs, rhs);
+        bailoutIf(c, snapshot);
+    }
+    void bailoutIfFalseBool(Register reg, LSnapshot* snapshot) {
+        masm.test32(reg, Imm32(0xFF));
+        bailoutIf(Assembler::Zero, snapshot);
+    }
+
+    template<class T>
+    void generateUDivModZeroCheck(Register rhs, Register output, Label* done, LSnapshot* snapshot,
+                                  T* mir);
+
+  protected:
+    bool generateOutOfLineCode();
+
+    void emitRoundDouble(FloatRegister src, Register dest, Label* fail);
+
+    // Emits a branch that directs control flow to the true block if |cond| is
+    // true, and the false block if |cond| is false.
+    void emitBranch(Assembler::Condition cond, MBasicBlock* ifTrue, MBasicBlock* ifFalse);
+
+    void testNullEmitBranch(Assembler::Condition cond, const ValueOperand& value,
+                            MBasicBlock* ifTrue, MBasicBlock* ifFalse)
+    {
+        cond = masm.testNull(cond, value);
+        emitBranch(cond, ifTrue, ifFalse);
+    }
+    void testUndefinedEmitBranch(Assembler::Condition cond, const ValueOperand& value,
+                                 MBasicBlock* ifTrue, MBasicBlock* ifFalse)
+    {
+        cond = masm.testUndefined(cond, value);
+        emitBranch(cond, ifTrue, ifFalse);
+    }
+    void testObjectEmitBranch(Assembler::Condition cond, const ValueOperand& value,
+                              MBasicBlock* ifTrue, MBasicBlock* ifFalse)
+    {
+        cond = masm.testObject(cond, value);
+        emitBranch(cond, ifTrue, ifFalse);
+    }
+    void testZeroEmitBranch(Assembler::Condition cond, Register reg,
+                            MBasicBlock* ifTrue, MBasicBlock* ifFalse)
+    {
+        MOZ_ASSERT(cond == Assembler::Equal || cond == Assembler::NotEqual);
+        masm.cmpPtr(reg, ImmWord(0));
+        emitBranch(cond, ifTrue, ifFalse);
+    }
+
+    void emitTableSwitchDispatch(MTableSwitch* mir, Register index, Register base);
+
+    template <typename T>
+    void emitWasmLoad(T* ins);
+    template <typename T>
+    void emitWasmUnalignedLoad(T* ins);
+    template <typename T>
+    void emitWasmStore(T* ins);
+    template <typename T>
+    void emitWasmUnalignedStore(T* ins);
+
+  public:
+    // Instruction visitors.
+    virtual void visitMinMaxD(LMinMaxD* ins);
+    virtual void visitMinMaxF(LMinMaxF* ins);
+    virtual void visitAbsD(LAbsD* ins);
+    virtual void visitAbsF(LAbsF* ins);
+    virtual void visitSqrtD(LSqrtD* ins);
+    virtual void visitSqrtF(LSqrtF* ins);
+    virtual void visitAddI(LAddI* ins);
+    virtual void visitSubI(LSubI* ins);
+    virtual void visitBitNotI(LBitNotI* ins);
+    virtual void visitBitOpI(LBitOpI* ins);
+
+    virtual void visitMulI(LMulI* ins);
+
+    virtual void visitDivI(LDivI* ins);
+    virtual void visitSoftDivI(LSoftDivI* ins);
+    virtual void visitDivPowTwoI(LDivPowTwoI* ins);
+    virtual void visitModI(LModI* ins);
+    virtual void visitSoftModI(LSoftModI* ins);
+    virtual void visitModPowTwoI(LModPowTwoI* ins);
+    virtual void visitModMaskI(LModMaskI* ins);
+    virtual void visitPowHalfD(LPowHalfD* ins);
+    virtual void visitShiftI(LShiftI* ins);
+    virtual void visitShiftI64(LShiftI64* ins);
+    virtual void visitUrshD(LUrshD* ins);
+
+    virtual void visitClzI(LClzI* ins);
+    virtual void visitCtzI(LCtzI* ins);
+    virtual void visitPopcntI(LPopcntI* ins);
+
+    virtual void visitTestIAndBranch(LTestIAndBranch* test);
+    virtual void visitCompare(LCompare* comp);
+    virtual void visitCompareAndBranch(LCompareAndBranch* comp);
+    virtual void visitTestDAndBranch(LTestDAndBranch* test);
+    virtual void visitTestFAndBranch(LTestFAndBranch* test);
+    virtual void visitCompareD(LCompareD* comp);
+    virtual void visitCompareF(LCompareF* comp);
+    virtual void visitCompareDAndBranch(LCompareDAndBranch* comp);
+    virtual void visitCompareFAndBranch(LCompareFAndBranch* comp);
+    virtual void visitCompareB(LCompareB* lir);
+    virtual void visitCompareBAndBranch(LCompareBAndBranch* lir);
+    virtual void visitCompareBitwise(LCompareBitwise* lir);
+    virtual void visitCompareBitwiseAndBranch(LCompareBitwiseAndBranch* lir);
+    virtual void visitBitAndAndBranch(LBitAndAndBranch* baab);
+    virtual void visitWasmUint32ToDouble(LWasmUint32ToDouble* lir);
+    virtual void visitWasmUint32ToFloat32(LWasmUint32ToFloat32* lir);
+    virtual void visitNotI(LNotI* ins);
+    virtual void visitNotD(LNotD* ins);
+    virtual void visitNotF(LNotF* ins);
+
+    virtual void visitMathD(LMathD* math);
+    virtual void visitMathF(LMathF* math);
+    virtual void visitFloor(LFloor* lir);
+    virtual void visitFloorF(LFloorF* lir);
+    virtual void visitCeil(LCeil* lir);
+    virtual void visitCeilF(LCeilF* lir);
+    virtual void visitRound(LRound* lir);
+    virtual void visitRoundF(LRoundF* lir);
+    virtual void visitTruncateDToInt32(LTruncateDToInt32* ins);
+    virtual void visitTruncateFToInt32(LTruncateFToInt32* ins);
+
+    virtual void visitWrapInt64ToInt32(LWrapInt64ToInt32* lir);
+    virtual void visitExtendInt32ToInt64(LExtendInt32ToInt64* lir);
+    virtual void visitAddI64(LAddI64* lir);
+    virtual void visitSubI64(LSubI64* lir);
+    virtual void visitMulI64(LMulI64* lir);
+    virtual void visitDivOrModI64(LDivOrModI64* lir);
+    virtual void visitUDivOrModI64(LUDivOrModI64* lir);
+    virtual void visitCompareI64(LCompareI64* lir);
+    virtual void visitCompareI64AndBranch(LCompareI64AndBranch* lir);
+    virtual void visitBitOpI64(LBitOpI64* lir);
+    virtual void visitRotateI64(LRotateI64* lir);
+    virtual void visitWasmStackArgI64(LWasmStackArgI64* lir);
+    virtual void visitWasmSelectI64(LWasmSelectI64* lir);
+    virtual void visitWasmReinterpretFromI64(LWasmReinterpretFromI64* lir);
+    virtual void visitWasmReinterpretToI64(LWasmReinterpretToI64* lir);
+    virtual void visitPopcntI64(LPopcntI64* ins);
+    virtual void visitClzI64(LClzI64* ins);
+    virtual void visitCtzI64(LCtzI64* ins);
+    virtual void visitNotI64(LNotI64* ins);
+    virtual void visitWasmTruncateToInt64(LWasmTruncateToInt64* ins);
+    virtual void visitInt64ToFloatingPointCall(LInt64ToFloatingPointCall* lir);
+    virtual void visitTestI64AndBranch(LTestI64AndBranch* lir);
+
+    // Out of line visitors.
+    void visitOutOfLineBailout(OutOfLineBailout* ool);
+    void visitOutOfLineTableSwitch(OutOfLineTableSwitch* ool);
+
+  protected:
+    ValueOperand ToValue(LInstruction* ins, size_t pos);
+    ValueOperand ToOutValue(LInstruction* ins);
+    ValueOperand ToTempValue(LInstruction* ins, size_t pos);
+
+    Register64 ToOperandOrRegister64(const LInt64Allocation input);
+
+    // Functions for LTestVAndBranch.
+    Register splitTagForTest(const ValueOperand& value);
+
+    void divICommon(MDiv* mir, Register lhs, Register rhs, Register output, LSnapshot* snapshot,
+                    Label& done);
+    void modICommon(MMod* mir, Register lhs, Register rhs, Register output, LSnapshot* snapshot,
+                    Label& done);
+
+  public:
+    CodeGeneratorARM(MIRGenerator* gen, LIRGraph* graph, MacroAssembler* masm);
+
+  public:
+    void visitBox(LBox* box);
+    void visitBoxFloatingPoint(LBoxFloatingPoint* box);
+    void visitUnbox(LUnbox* unbox);
+    void visitValue(LValue* value);
+    void visitDouble(LDouble* ins);
+    void visitFloat32(LFloat32* ins);
+
+    void visitGuardShape(LGuardShape* guard);
+    void visitGuardObjectGroup(LGuardObjectGroup* guard);
+    void visitGuardClass(LGuardClass* guard);
+
+    void visitNegI(LNegI* lir);
+    void visitNegD(LNegD* lir);
+    void visitNegF(LNegF* lir);
+    void visitLoadTypedArrayElementStatic(LLoadTypedArrayElementStatic* ins);
+    void visitStoreTypedArrayElementStatic(LStoreTypedArrayElementStatic* ins);
+    void visitAtomicTypedArrayElementBinop(LAtomicTypedArrayElementBinop* lir);
+    void visitAtomicTypedArrayElementBinopForEffect(LAtomicTypedArrayElementBinopForEffect* lir);
+    void visitCompareExchangeTypedArrayElement(LCompareExchangeTypedArrayElement* lir);
+    void visitAtomicExchangeTypedArrayElement(LAtomicExchangeTypedArrayElement* lir);
+    void visitWasmSelect(LWasmSelect* ins);
+    void visitWasmReinterpret(LWasmReinterpret* ins);
+    void emitWasmCall(LWasmCallBase* ins);
+    void visitWasmCall(LWasmCall* ins);
+    void visitWasmCallI64(LWasmCallI64* ins);
+    void visitWasmLoad(LWasmLoad* ins);
+    void visitWasmLoadI64(LWasmLoadI64* ins);
+    void visitWasmUnalignedLoad(LWasmUnalignedLoad* ins);
+    void visitWasmUnalignedLoadI64(LWasmUnalignedLoadI64* ins);
+    void visitWasmAddOffset(LWasmAddOffset* ins);
+    void visitWasmStore(LWasmStore* ins);
+    void visitWasmStoreI64(LWasmStoreI64* ins);
+    void visitWasmUnalignedStore(LWasmUnalignedStore* ins);
+    void visitWasmUnalignedStoreI64(LWasmUnalignedStoreI64* ins);
+    void visitWasmLoadGlobalVar(LWasmLoadGlobalVar* ins);
+    void visitWasmLoadGlobalVarI64(LWasmLoadGlobalVarI64* ins);
+    void visitWasmStoreGlobalVar(LWasmStoreGlobalVar* ins);
+    void visitWasmStoreGlobalVarI64(LWasmStoreGlobalVarI64* ins);
+    void visitAsmJSLoadHeap(LAsmJSLoadHeap* ins);
+    void visitAsmJSStoreHeap(LAsmJSStoreHeap* ins);
+    void visitAsmJSCompareExchangeHeap(LAsmJSCompareExchangeHeap* ins);
+    void visitAsmJSCompareExchangeCallout(LAsmJSCompareExchangeCallout* ins);
+    void visitAsmJSAtomicExchangeHeap(LAsmJSAtomicExchangeHeap* ins);
+    void visitAsmJSAtomicExchangeCallout(LAsmJSAtomicExchangeCallout* ins);
+    void visitAsmJSAtomicBinopHeap(LAsmJSAtomicBinopHeap* ins);
+    void visitAsmJSAtomicBinopHeapForEffect(LAsmJSAtomicBinopHeapForEffect* ins);
+    void visitAsmJSAtomicBinopCallout(LAsmJSAtomicBinopCallout* ins);
+    void visitWasmStackArg(LWasmStackArg* ins);
+    void visitWasmTruncateToInt32(LWasmTruncateToInt32* ins);
+    void visitOutOfLineWasmTruncateCheck(OutOfLineWasmTruncateCheck* ool);
+    void visitCopySignD(LCopySignD* ins);
+    void visitCopySignF(LCopySignF* ins);
+
+    void visitMemoryBarrier(LMemoryBarrier* ins);
+
+    void generateInvalidateEpilogue();
+
+    void setReturnDoubleRegs(LiveRegisterSet* regs);
+
+    // Generating a result.
+    template<typename S, typename T>
+    void atomicBinopToTypedIntArray(AtomicOp op, Scalar::Type arrayType, const S& value,
+                                    const T& mem, Register flagTemp, Register outTemp,
+                                    AnyRegister output);
+
+    // Generating no result.
+    template<typename S, typename T>
+    void atomicBinopToTypedIntArray(AtomicOp op, Scalar::Type arrayType, const S& value,
+                                    const T& mem, Register flagTemp);
+
+  protected:
+    void visitEffectiveAddress(LEffectiveAddress* ins);
+    void visitUDiv(LUDiv* ins);
+    void visitUMod(LUMod* ins);
+    void visitSoftUDivOrMod(LSoftUDivOrMod* ins);
+
+  public:
+    // Unimplemented SIMD instructions
+    void visitSimdSplatX4(LSimdSplatX4* lir) { MOZ_CRASH("NYI"); }
+    void visitSimd128Int(LSimd128Int* ins) { MOZ_CRASH("NYI"); }
+    void visitSimd128Float(LSimd128Float* ins) { MOZ_CRASH("NYI"); }
+    void visitSimdReinterpretCast(LSimdReinterpretCast* ins) { MOZ_CRASH("NYI"); }
+    void visitSimdExtractElementI(LSimdExtractElementI* ins) { MOZ_CRASH("NYI"); }
+    void visitSimdExtractElementF(LSimdExtractElementF* ins) { MOZ_CRASH("NYI"); }
+    void visitSimdGeneralShuffleI(LSimdGeneralShuffleI* lir) { MOZ_CRASH("NYI"); }
+    void visitSimdGeneralShuffleF(LSimdGeneralShuffleF* lir) { MOZ_CRASH("NYI"); }
+    void visitSimdSwizzleI(LSimdSwizzleI* lir) { MOZ_CRASH("NYI"); }
+    void visitSimdSwizzleF(LSimdSwizzleF* lir) { MOZ_CRASH("NYI"); }
+    void visitSimdBinaryCompIx4(LSimdBinaryCompIx4* lir) { MOZ_CRASH("NYI"); }
+    void visitSimdBinaryCompFx4(LSimdBinaryCompFx4* lir) { MOZ_CRASH("NYI"); }
+    void visitSimdBinaryArithIx4(LSimdBinaryArithIx4* lir) { MOZ_CRASH("NYI"); }
+    void visitSimdBinaryArithFx4(LSimdBinaryArithFx4* lir) { MOZ_CRASH("NYI"); }
+    void visitSimdBinaryBitwise(LSimdBinaryBitwise* lir) { MOZ_CRASH("NYI"); }
+};
+
+typedef CodeGeneratorARM CodeGeneratorSpecific;
+
+// An out-of-line bailout thunk.
+class OutOfLineBailout : public OutOfLineCodeBase<CodeGeneratorARM>
+{
+  protected: // Silence Clang warning.
+    LSnapshot* snapshot_;
+    uint32_t frameSize_;
+
+  public:
+    OutOfLineBailout(LSnapshot* snapshot, uint32_t frameSize)
+      : snapshot_(snapshot),
+        frameSize_(frameSize)
+    { }
+
+    void accept(CodeGeneratorARM* codegen);
+
+    LSnapshot* snapshot() const {
+        return snapshot_;
+    }
+};
+
+} // namespace jit
+} // namespace js
+
+#endif /* jit_arm_CodeGenerator_arm_h */
diff --git a/js/src/jit/arm/DoubleEntryTable.tbl b/js/src/jit/arm/DoubleEntryTable.tbl
new file mode 100644
index 0000000000..2e9e8c4a34
--- /dev/null
+++ b/js/src/jit/arm/DoubleEntryTable.tbl
@@ -0,0 +1,257 @@
+/* THIS FILE IS AUTOMATICALLY GENERATED BY gen-double-encode-table.py.  */
+  { 0x40000000, { 0, 0, 0 } },
+  { 0x40010000, { 1, 0, 0 } },
+  { 0x40020000, { 2, 0, 0 } },
+  { 0x40030000, { 3, 0, 0 } },
+  { 0x40040000, { 4, 0, 0 } },
+  { 0x40050000, { 5, 0, 0 } },
+  { 0x40060000, { 6, 0, 0 } },
+  { 0x40070000, { 7, 0, 0 } },
+  { 0x40080000, { 8, 0, 0 } },
+  { 0x40090000, { 9, 0, 0 } },
+  { 0x400a0000, { 10, 0, 0 } },
+  { 0x400b0000, { 11, 0, 0 } },
+  { 0x400c0000, { 12, 0, 0 } },
+  { 0x400d0000, { 13, 0, 0 } },
+  { 0x400e0000, { 14, 0, 0 } },
+  { 0x400f0000, { 15, 0, 0 } },
+  { 0x40100000, { 0, 1, 0 } },
+  { 0x40110000, { 1, 1, 0 } },
+  { 0x40120000, { 2, 1, 0 } },
+  { 0x40130000, { 3, 1, 0 } },
+  { 0x40140000, { 4, 1, 0 } },
+  { 0x40150000, { 5, 1, 0 } },
+  { 0x40160000, { 6, 1, 0 } },
+  { 0x40170000, { 7, 1, 0 } },
+  { 0x40180000, { 8, 1, 0 } },
+  { 0x40190000, { 9, 1, 0 } },
+  { 0x401a0000, { 10, 1, 0 } },
+  { 0x401b0000, { 11, 1, 0 } },
+  { 0x401c0000, { 12, 1, 0 } },
+  { 0x401d0000, { 13, 1, 0 } },
+  { 0x401e0000, { 14, 1, 0 } },
+  { 0x401f0000, { 15, 1, 0 } },
+  { 0x40200000, { 0, 2, 0 } },
+  { 0x40210000, { 1, 2, 0 } },
+  { 0x40220000, { 2, 2, 0 } },
+  { 0x40230000, { 3, 2, 0 } },
+  { 0x40240000, { 4, 2, 0 } },
+  { 0x40250000, { 5, 2, 0 } },
+  { 0x40260000, { 6, 2, 0 } },
+  { 0x40270000, { 7, 2, 0 } },
+  { 0x40280000, { 8, 2, 0 } },
+  { 0x40290000, { 9, 2, 0 } },
+  { 0x402a0000, { 10, 2, 0 } },
+  { 0x402b0000, { 11, 2, 0 } },
+  { 0x402c0000, { 12, 2, 0 } },
+  { 0x402d0000, { 13, 2, 0 } },
+  { 0x402e0000, { 14, 2, 0 } },
+  { 0x402f0000, { 15, 2, 0 } },
+  { 0x40300000, { 0, 3, 0 } },
+  { 0x40310000, { 1, 3, 0 } },
+  { 0x40320000, { 2, 3, 0 } },
+  { 0x40330000, { 3, 3, 0 } },
+  { 0x40340000, { 4, 3, 0 } },
+  { 0x40350000, { 5, 3, 0 } },
+  { 0x40360000, { 6, 3, 0 } },
+  { 0x40370000, { 7, 3, 0 } },
+  { 0x40380000, { 8, 3, 0 } },
+  { 0x40390000, { 9, 3, 0 } },
+  { 0x403a0000, { 10, 3, 0 } },
+  { 0x403b0000, { 11, 3, 0 } },
+  { 0x403c0000, { 12, 3, 0 } },
+  { 0x403d0000, { 13, 3, 0 } },
+  { 0x403e0000, { 14, 3, 0 } },
+  { 0x403f0000, { 15, 3, 0 } },
+  { 0x3fc00000, { 0, 4, 0 } },
+  { 0x3fc10000, { 1, 4, 0 } },
+  { 0x3fc20000, { 2, 4, 0 } },
+  { 0x3fc30000, { 3, 4, 0 } },
+  { 0x3fc40000, { 4, 4, 0 } },
+  { 0x3fc50000, { 5, 4, 0 } },
+  { 0x3fc60000, { 6, 4, 0 } },
+  { 0x3fc70000, { 7, 4, 0 } },
+  { 0x3fc80000, { 8, 4, 0 } },
+  { 0x3fc90000, { 9, 4, 0 } },
+  { 0x3fca0000, { 10, 4, 0 } },
+  { 0x3fcb0000, { 11, 4, 0 } },
+  { 0x3fcc0000, { 12, 4, 0 } },
+  { 0x3fcd0000, { 13, 4, 0 } },
+  { 0x3fce0000, { 14, 4, 0 } },
+  { 0x3fcf0000, { 15, 4, 0 } },
+  { 0x3fd00000, { 0, 5, 0 } },
+  { 0x3fd10000, { 1, 5, 0 } },
+  { 0x3fd20000, { 2, 5, 0 } },
+  { 0x3fd30000, { 3, 5, 0 } },
+  { 0x3fd40000, { 4, 5, 0 } },
+  { 0x3fd50000, { 5, 5, 0 } },
+  { 0x3fd60000, { 6, 5, 0 } },
+  { 0x3fd70000, { 7, 5, 0 } },
+  { 0x3fd80000, { 8, 5, 0 } },
+  { 0x3fd90000, { 9, 5, 0 } },
+  { 0x3fda0000, { 10, 5, 0 } },
+  { 0x3fdb0000, { 11, 5, 0 } },
+  { 0x3fdc0000, { 12, 5, 0 } },
+  { 0x3fdd0000, { 13, 5, 0 } },
+  { 0x3fde0000, { 14, 5, 0 } },
+  { 0x3fdf0000, { 15, 5, 0 } },
+  { 0x3fe00000, { 0, 6, 0 } },
+  { 0x3fe10000, { 1, 6, 0 } },
+  { 0x3fe20000, { 2, 6, 0 } },
+  { 0x3fe30000, { 3, 6, 0 } },
+  { 0x3fe40000, { 4, 6, 0 } },
+  { 0x3fe50000, { 5, 6, 0 } },
+  { 0x3fe60000, { 6, 6, 0 } },
+  { 0x3fe70000, { 7, 6, 0 } },
+  { 0x3fe80000, { 8, 6, 0 } },
+  { 0x3fe90000, { 9, 6, 0 } },
+  { 0x3fea0000, { 10, 6, 0 } },
+  { 0x3feb0000, { 11, 6, 0 } },
+  { 0x3fec0000, { 12, 6, 0 } },
+  { 0x3fed0000, { 13, 6, 0 } },
+  { 0x3fee0000, { 14, 6, 0 } },
+  { 0x3fef0000, { 15, 6, 0 } },
+  { 0x3ff00000, { 0, 7, 0 } },
+  { 0x3ff10000, { 1, 7, 0 } },
+  { 0x3ff20000, { 2, 7, 0 } },
+  { 0x3ff30000, { 3, 7, 0 } },
+  { 0x3ff40000, { 4, 7, 0 } },
+  { 0x3ff50000, { 5, 7, 0 } },
+  { 0x3ff60000, { 6, 7, 0 } },
+  { 0x3ff70000, { 7, 7, 0 } },
+  { 0x3ff80000, { 8, 7, 0 } },
+  { 0x3ff90000, { 9, 7, 0 } },
+  { 0x3ffa0000, { 10, 7, 0 } },
+  { 0x3ffb0000, { 11, 7, 0 } },
+  { 0x3ffc0000, { 12, 7, 0 } },
+  { 0x3ffd0000, { 13, 7, 0 } },
+  { 0x3ffe0000, { 14, 7, 0 } },
+  { 0x3fff0000, { 15, 7, 0 } },
+  { 0xc0000000, { 0, 8, 0 } },
+  { 0xc0010000, { 1, 8, 0 } },
+  { 0xc0020000, { 2, 8, 0 } },
+  { 0xc0030000, { 3, 8, 0 } },
+  { 0xc0040000, { 4, 8, 0 } },
+  { 0xc0050000, { 5, 8, 0 } },
+  { 0xc0060000, { 6, 8, 0 } },
+  { 0xc0070000, { 7, 8, 0 } },
+  { 0xc0080000, { 8, 8, 0 } },
+  { 0xc0090000, { 9, 8, 0 } },
+  { 0xc00a0000, { 10, 8, 0 } },
+  { 0xc00b0000, { 11, 8, 0 } },
+  { 0xc00c0000, { 12, 8, 0 } },
+  { 0xc00d0000, { 13, 8, 0 } },
+  { 0xc00e0000, { 14, 8, 0 } },
+  { 0xc00f0000, { 15, 8, 0 } },
+  { 0xc0100000, { 0, 9, 0 } },
+  { 0xc0110000, { 1, 9, 0 } },
+  { 0xc0120000, { 2, 9, 0 } },
+  { 0xc0130000, { 3, 9, 0 } },
+  { 0xc0140000, { 4, 9, 0 } },
+  { 0xc0150000, { 5, 9, 0 } },
+  { 0xc0160000, { 6, 9, 0 } },
+  { 0xc0170000, { 7, 9, 0 } },
+  { 0xc0180000, { 8, 9, 0 } },
+  { 0xc0190000, { 9, 9, 0 } },
+  { 0xc01a0000, { 10, 9, 0 } },
+  { 0xc01b0000, { 11, 9, 0 } },
+  { 0xc01c0000, { 12, 9, 0 } },
+  { 0xc01d0000, { 13, 9, 0 } },
+  { 0xc01e0000, { 14, 9, 0 } },
+  { 0xc01f0000, { 15, 9, 0 } },
+  { 0xc0200000, { 0, 10, 0 } },
+  { 0xc0210000, { 1, 10, 0 } },
+  { 0xc0220000, { 2, 10, 0 } },
+  { 0xc0230000, { 3, 10, 0 } },
+  { 0xc0240000, { 4, 10, 0 } },
+  { 0xc0250000, { 5, 10, 0 } },
+  { 0xc0260000, { 6, 10, 0 } },
+  { 0xc0270000, { 7, 10, 0 } },
+  { 0xc0280000, { 8, 10, 0 } },
+  { 0xc0290000, { 9, 10, 0 } },
+  { 0xc02a0000, { 10, 10, 0 } },
+  { 0xc02b0000, { 11, 10, 0 } },
+  { 0xc02c0000, { 12, 10, 0 } },
+  { 0xc02d0000, { 13, 10, 0 } },
+  { 0xc02e0000, { 14, 10, 0 } },
+  { 0xc02f0000, { 15, 10, 0 } },
+  { 0xc0300000, { 0, 11, 0 } },
+  { 0xc0310000, { 1, 11, 0 } },
+  { 0xc0320000, { 2, 11, 0 } },
+  { 0xc0330000, { 3, 11, 0 } },
+  { 0xc0340000, { 4, 11, 0 } },
+  { 0xc0350000, { 5, 11, 0 } },
+  { 0xc0360000, { 6, 11, 0 } },
+  { 0xc0370000, { 7, 11, 0 } },
+  { 0xc0380000, { 8, 11, 0 } },
+  { 0xc0390000, { 9, 11, 0 } },
+  { 0xc03a0000, { 10, 11, 0 } },
+  { 0xc03b0000, { 11, 11, 0 } },
+  { 0xc03c0000, { 12, 11, 0 } },
+  { 0xc03d0000, { 13, 11, 0 } },
+  { 0xc03e0000, { 14, 11, 0 } },
+  { 0xc03f0000, { 15, 11, 0 } },
+  { 0xbfc00000, { 0, 12, 0 } },
+  { 0xbfc10000, { 1, 12, 0 } },
+  { 0xbfc20000, { 2, 12, 0 } },
+  { 0xbfc30000, { 3, 12, 0 } },
+  { 0xbfc40000, { 4, 12, 0 } },
+  { 0xbfc50000, { 5, 12, 0 } },
+  { 0xbfc60000, { 6, 12, 0 } },
+  { 0xbfc70000, { 7, 12, 0 } },
+  { 0xbfc80000, { 8, 12, 0 } },
+  { 0xbfc90000, { 9, 12, 0 } },
+  { 0xbfca0000, { 10, 12, 0 } },
+  { 0xbfcb0000, { 11, 12, 0 } },
+  { 0xbfcc0000, { 12, 12, 0 } },
+  { 0xbfcd0000, { 13, 12, 0 } },
+  { 0xbfce0000, { 14, 12, 0 } },
+  { 0xbfcf0000, { 15, 12, 0 } },
+  { 0xbfd00000, { 0, 13, 0 } },
+  { 0xbfd10000, { 1, 13, 0 } },
+  { 0xbfd20000, { 2, 13, 0 } },
+  { 0xbfd30000, { 3, 13, 0 } },
+  { 0xbfd40000, { 4, 13, 0 } },
+  { 0xbfd50000, { 5, 13, 0 } },
+  { 0xbfd60000, { 6, 13, 0 } },
+  { 0xbfd70000, { 7, 13, 0 } },
+  { 0xbfd80000, { 8, 13, 0 } },
+  { 0xbfd90000, { 9, 13, 0 } },
+  { 0xbfda0000, { 10, 13, 0 } },
+  { 0xbfdb0000, { 11, 13, 0 } },
+  { 0xbfdc0000, { 12, 13, 0 } },
+  { 0xbfdd0000, { 13, 13, 0 } },
+  { 0xbfde0000, { 14, 13, 0 } },
+  { 0xbfdf0000, { 15, 13, 0 } },
+  { 0xbfe00000, { 0, 14, 0 } },
+  { 0xbfe10000, { 1, 14, 0 } },
+  { 0xbfe20000, { 2, 14, 0 } },
+  { 0xbfe30000, { 3, 14, 0 } },
+  { 0xbfe40000, { 4, 14, 0 } },
+  { 0xbfe50000, { 5, 14, 0 } },
+  { 0xbfe60000, { 6, 14, 0 } },
+  { 0xbfe70000, { 7, 14, 0 } },
+  { 0xbfe80000, { 8, 14, 0 } },
+  { 0xbfe90000, { 9, 14, 0 } },
+  { 0xbfea0000, { 10, 14, 0 } },
+  { 0xbfeb0000, { 11, 14, 0 } },
+  { 0xbfec0000, { 12, 14, 0 } },
+  { 0xbfed0000, { 13, 14, 0 } },
+  { 0xbfee0000, { 14, 14, 0 } },
+  { 0xbfef0000, { 15, 14, 0 } },
+  { 0xbff00000, { 0, 15, 0 } },
+  { 0xbff10000, { 1, 15, 0 } },
+  { 0xbff20000, { 2, 15, 0 } },
+  { 0xbff30000, { 3, 15, 0 } },
+  { 0xbff40000, { 4, 15, 0 } },
+  { 0xbff50000, { 5, 15, 0 } },
+  { 0xbff60000, { 6, 15, 0 } },
+  { 0xbff70000, { 7, 15, 0 } },
+  { 0xbff80000, { 8, 15, 0 } },
+  { 0xbff90000, { 9, 15, 0 } },
+  { 0xbffa0000, { 10, 15, 0 } },
+  { 0xbffb0000, { 11, 15, 0 } },
+  { 0xbffc0000, { 12, 15, 0 } },
+  { 0xbffd0000, { 13, 15, 0 } },
+  { 0xbffe0000, { 14, 15, 0 } },
+  { 0xbfff0000, { 15, 15, 0 } },
diff --git a/js/src/jit/arm/LIR-arm.h b/js/src/jit/arm/LIR-arm.h
new file mode 100644
index 0000000000..c498bf28ea
--- /dev/null
+++ b/js/src/jit/arm/LIR-arm.h
@@ -0,0 +1,710 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef jit_arm_LIR_arm_h
+#define jit_arm_LIR_arm_h
+
+namespace js {
+namespace jit {
+
+class LBoxFloatingPoint : public LInstructionHelper<2, 1, 1>
+{
+    MIRType type_;
+
+  public:
+    LIR_HEADER(BoxFloatingPoint);
+
+    LBoxFloatingPoint(const LAllocation& in, const LDefinition& temp, MIRType type)
+      : type_(type)
+    {
+        setOperand(0, in);
+        setTemp(0, temp);
+    }
+
+    MIRType type() const {
+        return type_;
+    }
+    const char* extraName() const {
+        return StringFromMIRType(type_);
+    }
+};
+
+class LUnbox : public LInstructionHelper<1, 2, 0>
+{
+  public:
+    LIR_HEADER(Unbox);
+
+    MUnbox* mir() const {
+        return mir_->toUnbox();
+    }
+    const LAllocation* payload() {
+        return getOperand(0);
+    }
+    const LAllocation* type() {
+        return getOperand(1);
+    }
+    const char* extraName() const {
+        return StringFromMIRType(mir()->type());
+    }
+};
+
+class LUnboxFloatingPoint : public LInstructionHelper<1, 2, 0>
+{
+    MIRType type_;
+
+  public:
+    LIR_HEADER(UnboxFloatingPoint);
+
+    static const size_t Input = 0;
+
+    LUnboxFloatingPoint(const LBoxAllocation& input, MIRType type)
+      : type_(type)
+    {
+        setBoxOperand(Input, input);
+    }
+
+    MUnbox* mir() const {
+        return mir_->toUnbox();
+    }
+
+    MIRType type() const {
+        return type_;
+    }
+    const char* extraName() const {
+        return StringFromMIRType(type_);
+    }
+};
+
+// Convert a 32-bit unsigned integer to a double.
+class LWasmUint32ToDouble : public LInstructionHelper<1, 1, 0>
+{
+  public:
+    LIR_HEADER(WasmUint32ToDouble)
+
+    LWasmUint32ToDouble(const LAllocation& input) {
+        setOperand(0, input);
+    }
+};
+
+// Convert a 32-bit unsigned integer to a float32.
+class LWasmUint32ToFloat32 : public LInstructionHelper<1, 1, 0>
+{
+  public:
+    LIR_HEADER(WasmUint32ToFloat32)
+
+    LWasmUint32ToFloat32(const LAllocation& input) {
+        setOperand(0, input);
+    }
+};
+
+class LDivI : public LBinaryMath<1>
+{
+  public:
+    LIR_HEADER(DivI);
+
+    LDivI(const LAllocation& lhs, const LAllocation& rhs,
+          const LDefinition& temp) {
+        setOperand(0, lhs);
+        setOperand(1, rhs);
+        setTemp(0, temp);
+    }
+
+    MDiv* mir() const {
+        return mir_->toDiv();
+    }
+};
+
+class LDivOrModI64 : public LCallInstructionHelper<INT64_PIECES, INT64_PIECES*2, 0>
+{
+  public:
+    LIR_HEADER(DivOrModI64)
+
+    static const size_t Lhs = 0;
+    static const size_t Rhs = INT64_PIECES;
+
+    LDivOrModI64(const LInt64Allocation& lhs, const LInt64Allocation& rhs)
+    {
+        setInt64Operand(Lhs, lhs);
+        setInt64Operand(Rhs, rhs);
+    }
+
+    MBinaryArithInstruction* mir() const {
+        MOZ_ASSERT(mir_->isDiv() || mir_->isMod());
+        return static_cast<MBinaryArithInstruction*>(mir_);
+    }
+    bool canBeDivideByZero() const {
+        if (mir_->isMod())
+            return mir_->toMod()->canBeDivideByZero();
+        return mir_->toDiv()->canBeDivideByZero();
+    }
+    bool canBeNegativeOverflow() const {
+        if (mir_->isMod())
+            return mir_->toMod()->canBeNegativeDividend();
+        return mir_->toDiv()->canBeNegativeOverflow();
+    }
+    wasm::TrapOffset trapOffset() const {
+        MOZ_ASSERT(mir_->isDiv() || mir_->isMod());
+        if (mir_->isMod())
+            return mir_->toMod()->trapOffset();
+        return mir_->toDiv()->trapOffset();
+    }
+};
+
+class LUDivOrModI64 : public LCallInstructionHelper<INT64_PIECES, INT64_PIECES*2, 0>
+{
+  public:
+    LIR_HEADER(UDivOrModI64)
+
+    static const size_t Lhs = 0;
+    static const size_t Rhs = INT64_PIECES;
+
+    LUDivOrModI64(const LInt64Allocation& lhs, const LInt64Allocation& rhs)
+    {
+        setInt64Operand(Lhs, lhs);
+        setInt64Operand(Rhs, rhs);
+    }
+
+    MBinaryArithInstruction* mir() const {
+        MOZ_ASSERT(mir_->isDiv() || mir_->isMod());
+        return static_cast<MBinaryArithInstruction*>(mir_);
+    }
+    bool canBeDivideByZero() const {
+        if (mir_->isMod())
+            return mir_->toMod()->canBeDivideByZero();
+        return mir_->toDiv()->canBeDivideByZero();
+    }
+    bool canBeNegativeOverflow() const {
+        if (mir_->isMod())
+            return mir_->toMod()->canBeNegativeDividend();
+        return mir_->toDiv()->canBeNegativeOverflow();
+    }
+    wasm::TrapOffset trapOffset() const {
+        MOZ_ASSERT(mir_->isDiv() || mir_->isMod());
+        if (mir_->isMod())
+            return mir_->toMod()->trapOffset();
+        return mir_->toDiv()->trapOffset();
+    }
+};
+
+// LSoftDivI is a software divide for ARM cores that don't support a hardware
+// divide instruction.
+//
+// It is implemented as a proper C function so it trashes r0, r1, r2 and r3.
+// The call also trashes lr, and has the ability to trash ip. The function also
+// takes two arguments (dividend in r0, divisor in r1). The LInstruction gets
+// encoded such that the divisor and dividend are passed in their apropriate
+// registers and end their life at the start of the instruction by the use of
+// useFixedAtStart. The result is returned in r0 and the other three registers
+// that can be trashed are marked as temps. For the time being, the link
+// register is not marked as trashed because we never allocate to the link
+// register. The FP registers are not trashed.
+class LSoftDivI : public LBinaryMath<3>
+{
+  public:
+    LIR_HEADER(SoftDivI);
+
+    LSoftDivI(const LAllocation& lhs, const LAllocation& rhs,
+              const LDefinition& temp1, const LDefinition& temp2, const LDefinition& temp3) {
+        setOperand(0, lhs);
+        setOperand(1, rhs);
+        setTemp(0, temp1);
+        setTemp(1, temp2);
+        setTemp(2, temp3);
+    }
+
+    MDiv* mir() const {
+        return mir_->toDiv();
+    }
+};
+
+class LDivPowTwoI : public LInstructionHelper<1, 1, 0>
+{
+    const int32_t shift_;
+
+  public:
+    LIR_HEADER(DivPowTwoI)
+
+    LDivPowTwoI(const LAllocation& lhs, int32_t shift)
+      : shift_(shift)
+    {
+        setOperand(0, lhs);
+    }
+
+    const LAllocation* numerator() {
+        return getOperand(0);
+    }
+
+    int32_t shift() {
+        return shift_;
+    }
+
+    MDiv* mir() const {
+        return mir_->toDiv();
+    }
+};
+
+class LModI : public LBinaryMath<1>
+{
+  public:
+    LIR_HEADER(ModI);
+
+    LModI(const LAllocation& lhs, const LAllocation& rhs,
+          const LDefinition& callTemp)
+    {
+        setOperand(0, lhs);
+        setOperand(1, rhs);
+        setTemp(0, callTemp);
+    }
+
+    const LDefinition* callTemp() {
+        return getTemp(0);
+    }
+
+    MMod* mir() const {
+        return mir_->toMod();
+    }
+};
+
+class LSoftModI : public LBinaryMath<4>
+{
+  public:
+    LIR_HEADER(SoftModI);
+
+    LSoftModI(const LAllocation& lhs, const LAllocation& rhs,
+              const LDefinition& temp1, const LDefinition& temp2, const LDefinition& temp3,
+              const LDefinition& callTemp)
+    {
+        setOperand(0, lhs);
+        setOperand(1, rhs);
+        setTemp(0, temp1);
+        setTemp(1, temp2);
+        setTemp(2, temp3);
+        setTemp(3, callTemp);
+    }
+
+    const LDefinition* callTemp() {
+        return getTemp(3);
+    }
+
+    MMod* mir() const {
+        return mir_->toMod();
+    }
+};
+
+class LModPowTwoI : public LInstructionHelper<1, 1, 0>
+{
+    const int32_t shift_;
+
+  public:
+    LIR_HEADER(ModPowTwoI);
+    int32_t shift()
+    {
+        return shift_;
+    }
+
+    LModPowTwoI(const LAllocation& lhs, int32_t shift)
+      : shift_(shift)
+    {
+        setOperand(0, lhs);
+    }
+
+    MMod* mir() const {
+        return mir_->toMod();
+    }
+};
+
+class LModMaskI : public LInstructionHelper<1, 1, 2>
+{
+    const int32_t shift_;
+
+  public:
+    LIR_HEADER(ModMaskI);
+
+    LModMaskI(const LAllocation& lhs, const LDefinition& temp1, const LDefinition& temp2,
+              int32_t shift)
+      : shift_(shift)
+    {
+        setOperand(0, lhs);
+        setTemp(0, temp1);
+        setTemp(1, temp2);
+    }
+
+    int32_t shift() const {
+        return shift_;
+    }
+
+    MMod* mir() const {
+        return mir_->toMod();
+    }
+};
+
+// Takes a tableswitch with an integer to decide.
+class LTableSwitch : public LInstructionHelper<0, 1, 1>
+{
+  public:
+    LIR_HEADER(TableSwitch);
+
+    LTableSwitch(const LAllocation& in, const LDefinition& inputCopy, MTableSwitch* ins) {
+        setOperand(0, in);
+        setTemp(0, inputCopy);
+        setMir(ins);
+    }
+
+    MTableSwitch* mir() const {
+        return mir_->toTableSwitch();
+    }
+
+    const LAllocation* index() {
+        return getOperand(0);
+    }
+    const LDefinition* tempInt() {
+        return getTemp(0);
+    }
+    // This is added to share the same CodeGenerator prefixes.
+    const LDefinition* tempPointer() {
+        return nullptr;
+    }
+};
+
+// Takes a tableswitch with an integer to decide.
+class LTableSwitchV : public LInstructionHelper<0, BOX_PIECES, 2>
+{
+  public:
+    LIR_HEADER(TableSwitchV);
+
+    LTableSwitchV(const LBoxAllocation& input, const LDefinition& inputCopy,
+                  const LDefinition& floatCopy, MTableSwitch* ins)
+    {
+        setBoxOperand(InputValue, input);
+        setTemp(0, inputCopy);
+        setTemp(1, floatCopy);
+        setMir(ins);
+    }
+
+    MTableSwitch* mir() const {
+        return mir_->toTableSwitch();
+    }
+
+    static const size_t InputValue = 0;
+
+    const LDefinition* tempInt() {
+        return getTemp(0);
+    }
+    const LDefinition* tempFloat() {
+        return getTemp(1);
+    }
+    const LDefinition* tempPointer() {
+        return nullptr;
+    }
+};
+
+class LGuardShape : public LInstructionHelper<0, 1, 1>
+{
+  public:
+    LIR_HEADER(GuardShape);
+
+    LGuardShape(const LAllocation& in, const LDefinition& temp) {
+        setOperand(0, in);
+        setTemp(0, temp);
+    }
+    const MGuardShape* mir() const {
+        return mir_->toGuardShape();
+    }
+    const LDefinition* tempInt() {
+        return getTemp(0);
+    }
+};
+
+class LGuardObjectGroup : public LInstructionHelper<0, 1, 1>
+{
+  public:
+    LIR_HEADER(GuardObjectGroup);
+
+    LGuardObjectGroup(const LAllocation& in, const LDefinition& temp) {
+        setOperand(0, in);
+        setTemp(0, temp);
+    }
+    const MGuardObjectGroup* mir() const {
+        return mir_->toGuardObjectGroup();
+    }
+    const LDefinition* tempInt() {
+        return getTemp(0);
+    }
+};
+
+class LMulI : public LBinaryMath<0>
+{
+  public:
+    LIR_HEADER(MulI);
+
+    MMul* mir() {
+        return mir_->toMul();
+    }
+};
+
+class LUDiv : public LBinaryMath<0>
+{
+  public:
+    LIR_HEADER(UDiv);
+
+    MDiv* mir() {
+        return mir_->toDiv();
+    }
+};
+
+class LUMod : public LBinaryMath<0>
+{
+  public:
+    LIR_HEADER(UMod);
+
+    MMod* mir() {
+        return mir_->toMod();
+    }
+};
+
+class LSoftUDivOrMod : public LBinaryMath<3>
+{
+  public:
+    LIR_HEADER(SoftUDivOrMod);
+
+    LSoftUDivOrMod(const LAllocation& lhs, const LAllocation& rhs, const LDefinition& temp1,
+                   const LDefinition& temp2, const LDefinition& temp3) {
+        setOperand(0, lhs);
+        setOperand(1, rhs);
+        setTemp(0, temp1);
+        setTemp(1, temp2);
+        setTemp(2, temp3);
+    }
+
+    MInstruction* mir() {
+        return mir_->toInstruction();
+    }
+};
+
+class LAsmJSCompareExchangeCallout : public LCallInstructionHelper<1, 4, 2>
+{
+  public:
+    LIR_HEADER(AsmJSCompareExchangeCallout)
+    LAsmJSCompareExchangeCallout(const LAllocation& ptr, const LAllocation& oldval,
+                                 const LAllocation& newval, const LAllocation& tls,
+                                 const LDefinition& temp1, const LDefinition& temp2)
+    {
+        setOperand(0, ptr);
+        setOperand(1, oldval);
+        setOperand(2, newval);
+        setOperand(3, tls);
+        setTemp(0, temp1);
+        setTemp(1, temp2);
+    }
+    const LAllocation* ptr() {
+        return getOperand(0);
+    }
+    const LAllocation* oldval() {
+        return getOperand(1);
+    }
+    const LAllocation* newval() {
+        return getOperand(2);
+    }
+    const LAllocation* tls() {
+        return getOperand(3);
+    }
+
+    const MAsmJSCompareExchangeHeap* mir() const {
+        return mir_->toAsmJSCompareExchangeHeap();
+    }
+};
+
+class LAsmJSAtomicExchangeCallout : public LCallInstructionHelper<1, 3, 2>
+{
+  public:
+    LIR_HEADER(AsmJSAtomicExchangeCallout)
+
+    LAsmJSAtomicExchangeCallout(const LAllocation& ptr, const LAllocation& value,
+                                const LAllocation& tls, const LDefinition& temp1,
+                                const LDefinition& temp2)
+    {
+        setOperand(0, ptr);
+        setOperand(1, value);
+        setOperand(2, tls);
+        setTemp(0, temp1);
+        setTemp(1, temp2);
+    }
+    const LAllocation* ptr() {
+        return getOperand(0);
+    }
+    const LAllocation* value() {
+        return getOperand(1);
+    }
+    const LAllocation* tls() {
+        return getOperand(2);
+    }
+
+    const MAsmJSAtomicExchangeHeap* mir() const {
+        return mir_->toAsmJSAtomicExchangeHeap();
+    }
+};
+
+class LAsmJSAtomicBinopCallout : public LCallInstructionHelper<1, 3, 2>
+{
+  public:
+    LIR_HEADER(AsmJSAtomicBinopCallout)
+    LAsmJSAtomicBinopCallout(const LAllocation& ptr, const LAllocation& value,
+                             const LAllocation& tls, const LDefinition& temp1,
+                             const LDefinition& temp2)
+    {
+        setOperand(0, ptr);
+        setOperand(1, value);
+        setOperand(2, tls);
+        setTemp(0, temp1);
+        setTemp(1, temp2);
+    }
+    const LAllocation* ptr() {
+        return getOperand(0);
+    }
+    const LAllocation* value() {
+        return getOperand(1);
+    }
+    const LAllocation* tls() {
+        return getOperand(2);
+    }
+
+    const MAsmJSAtomicBinopHeap* mir() const {
+        return mir_->toAsmJSAtomicBinopHeap();
+    }
+};
+
+class LWasmTruncateToInt64 : public LCallInstructionHelper<INT64_PIECES, 1, 0>
+{
+  public:
+    LIR_HEADER(WasmTruncateToInt64);
+
+    LWasmTruncateToInt64(const LAllocation& in)
+    {
+        setOperand(0, in);
+    }
+
+    MWasmTruncateToInt64* mir() const {
+        return mir_->toWasmTruncateToInt64();
+    }
+};
+
+class LInt64ToFloatingPointCall: public LCallInstructionHelper<1, INT64_PIECES, 0>
+{
+  public:
+    LIR_HEADER(Int64ToFloatingPointCall);
+
+    MInt64ToFloatingPoint* mir() const {
+        return mir_->toInt64ToFloatingPoint();
+    }
+};
+
+namespace details {
+
+// Base class for the int64 and non-int64 variants.
+template<size_t NumDefs>
+class LWasmUnalignedLoadBase : public details::LWasmLoadBase<NumDefs, 4>
+{
+  public:
+    typedef LWasmLoadBase<NumDefs, 4> Base;
+    explicit LWasmUnalignedLoadBase(const LAllocation& ptr, const LDefinition& ptrCopy,
+                                    const LDefinition& temp1, const LDefinition& temp2,
+                                    const LDefinition& temp3)
+      : Base(ptr)
+    {
+        Base::setTemp(0, ptrCopy);
+        Base::setTemp(1, temp1);
+        Base::setTemp(2, temp2);
+        Base::setTemp(3, temp3);
+    }
+
+    const LDefinition* ptrCopy() {
+        return Base::getTemp(0);
+    }
+};
+
+} // namespace details
+
+class LWasmUnalignedLoad : public details::LWasmUnalignedLoadBase<1>
+{
+  public:
+    explicit LWasmUnalignedLoad(const LAllocation& ptr, const LDefinition& ptrCopy,
+                                const LDefinition& temp1, const LDefinition& temp2,
+                                const LDefinition& temp3)
+      : LWasmUnalignedLoadBase(ptr, ptrCopy, temp1, temp2, temp3)
+    {}
+    LIR_HEADER(WasmUnalignedLoad);
+};
+
+class LWasmUnalignedLoadI64 : public details::LWasmUnalignedLoadBase<INT64_PIECES>
+{
+  public:
+    explicit LWasmUnalignedLoadI64(const LAllocation& ptr, const LDefinition& ptrCopy,
+                                   const LDefinition& temp1, const LDefinition& temp2,
+                                   const LDefinition& temp3)
+      : LWasmUnalignedLoadBase(ptr, ptrCopy, temp1, temp2, temp3)
+    {}
+    LIR_HEADER(WasmUnalignedLoadI64);
+};
+
+namespace details {
+
+// Base class for the int64 and non-int64 variants.
+template<size_t NumOps>
+class LWasmUnalignedStoreBase : public LInstructionHelper<0, NumOps, 2>
+{
+  public:
+    typedef LInstructionHelper<0, NumOps, 2> Base;
+
+    static const uint32_t ValueIndex = 1;
+
+    LWasmUnalignedStoreBase(const LAllocation& ptr, const LDefinition& ptrCopy,
+                            const LDefinition& valueHelper)
+    {
+        Base::setOperand(0, ptr);
+        Base::setTemp(0, ptrCopy);
+        Base::setTemp(1, valueHelper);
+    }
+    MWasmStore* mir() const {
+        return Base::mir_->toWasmStore();
+    }
+    const LDefinition* ptrCopy() {
+        return Base::getTemp(0);
+    }
+    const LDefinition* valueHelper() {
+        return Base::getTemp(1);
+    }
+};
+
+} // namespace details
+
+class LWasmUnalignedStore : public details::LWasmUnalignedStoreBase<2>
+{
+  public:
+    LIR_HEADER(WasmUnalignedStore);
+    LWasmUnalignedStore(const LAllocation& ptr, const LAllocation& value,
+                        const LDefinition& ptrCopy, const LDefinition& valueHelper)
+      : LWasmUnalignedStoreBase(ptr, ptrCopy, valueHelper)
+    {
+        setOperand(1, value);
+    }
+};
+
+class LWasmUnalignedStoreI64 : public details::LWasmUnalignedStoreBase<1 + INT64_PIECES>
+{
+  public:
+    LIR_HEADER(WasmUnalignedStoreI64);
+    LWasmUnalignedStoreI64(const LAllocation& ptr, const LInt64Allocation& value,
+                           const LDefinition& ptrCopy, const LDefinition& valueHelper)
+      : LWasmUnalignedStoreBase(ptr, ptrCopy, valueHelper)
+    {
+        setInt64Operand(1, value);
+    }
+};
+
+} // namespace jit
+} // namespace js
+
+#endif /* jit_arm_LIR_arm_h */
diff --git a/js/src/jit/arm/LOpcodes-arm.h b/js/src/jit/arm/LOpcodes-arm.h
new file mode 100644
index 0000000000..13a4edd725
--- /dev/null
+++ b/js/src/jit/arm/LOpcodes-arm.h
@@ -0,0 +1,32 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef jit_arm_LOpcodes_arm_h
+#define jit_arm_LOpcodes_arm_h
+
+#include "jit/shared/LOpcodes-shared.h"
+
+#define LIR_CPU_OPCODE_LIST(_)     \
+    _(BoxFloatingPoint)            \
+    _(SoftDivI)                    \
+    _(SoftModI)                    \
+    _(ModMaskI)                    \
+    _(UDiv)                        \
+    _(UMod)                        \
+    _(SoftUDivOrMod)               \
+    _(AsmJSCompareExchangeCallout) \
+    _(AsmJSAtomicExchangeCallout)  \
+    _(AsmJSAtomicBinopCallout)     \
+    _(DivOrModI64)                 \
+    _(UDivOrModI64)                \
+    _(WasmTruncateToInt64)         \
+    _(WasmUnalignedLoad)           \
+    _(WasmUnalignedStore)          \
+    _(WasmUnalignedLoadI64)        \
+    _(WasmUnalignedStoreI64)       \
+    _(Int64ToFloatingPointCall)
+
+#endif /* jit_arm_LOpcodes_arm_h */
diff --git a/js/src/jit/arm/Lowering-arm.cpp b/js/src/jit/arm/Lowering-arm.cpp
new file mode 100644
index 0000000000..c266801162
--- /dev/null
+++ b/js/src/jit/arm/Lowering-arm.cpp
@@ -0,0 +1,1031 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "mozilla/MathAlgorithms.h"
+
+#include "jit/arm/Assembler-arm.h"
+#include "jit/Lowering.h"
+#include "jit/MIR.h"
+
+#include "jit/shared/Lowering-shared-inl.h"
+
+using namespace js;
+using namespace js::jit;
+
+using mozilla::FloorLog2;
+
+LBoxAllocation
+LIRGeneratorARM::useBoxFixed(MDefinition* mir, Register reg1, Register reg2, bool useAtStart)
+{
+    MOZ_ASSERT(mir->type() == MIRType::Value);
+    MOZ_ASSERT(reg1 != reg2);
+
+    ensureDefined(mir);
+    return LBoxAllocation(LUse(reg1, mir->virtualRegister(), useAtStart),
+                          LUse(reg2, VirtualRegisterOfPayload(mir), useAtStart));
+}
+
+LAllocation
+LIRGeneratorARM::useByteOpRegister(MDefinition* mir)
+{
+    return useRegister(mir);
+}
+
+LAllocation
+LIRGeneratorARM::useByteOpRegisterAtStart(MDefinition* mir)
+{
+    return useRegisterAtStart(mir);
+}
+
+LAllocation
+LIRGeneratorARM::useByteOpRegisterOrNonDoubleConstant(MDefinition* mir)
+{
+    return useRegisterOrNonDoubleConstant(mir);
+}
+
+LDefinition
+LIRGeneratorARM::tempByteOpRegister()
+{
+    return temp();
+}
+
+void
+LIRGeneratorARM::visitBox(MBox* box)
+{
+    MDefinition* inner = box->getOperand(0);
+
+    // If the box wrapped a double, it needs a new register.
+    if (IsFloatingPointType(inner->type())) {
+        defineBox(new(alloc()) LBoxFloatingPoint(useRegisterAtStart(inner), tempCopy(inner, 0),
+                                                 inner->type()), box);
+        return;
+    }
+
+    if (box->canEmitAtUses()) {
+        emitAtUses(box);
+        return;
+    }
+
+    if (inner->isConstant()) {
+        defineBox(new(alloc()) LValue(inner->toConstant()->toJSValue()), box);
+        return;
+    }
+
+    LBox* lir = new(alloc()) LBox(use(inner), inner->type());
+
+    // Otherwise, we should not define a new register for the payload portion
+    // of the output, so bypass defineBox().
+    uint32_t vreg = getVirtualRegister();
+
+    // Note that because we're using BogusTemp(), we do not change the type of
+    // the definition. We also do not define the first output as "TYPE",
+    // because it has no corresponding payload at (vreg + 1). Also note that
+    // although we copy the input's original type for the payload half of the
+    // definition, this is only for clarity. BogusTemp() definitions are
+    // ignored.
+    lir->setDef(0, LDefinition(vreg, LDefinition::GENERAL));
+    lir->setDef(1, LDefinition::BogusTemp());
+    box->setVirtualRegister(vreg);
+    add(lir);
+}
+
+void
+LIRGeneratorARM::visitUnbox(MUnbox* unbox)
+{
+    MDefinition* inner = unbox->getOperand(0);
+
+    if (inner->type() == MIRType::ObjectOrNull) {
+        LUnboxObjectOrNull* lir = new(alloc()) LUnboxObjectOrNull(useRegisterAtStart(inner));
+        if (unbox->fallible())
+            assignSnapshot(lir, unbox->bailoutKind());
+        defineReuseInput(lir, unbox, 0);
+        return;
+    }
+
+    // An unbox on arm reads in a type tag (either in memory or a register) and
+    // a payload. Unlike most instructions consuming a box, we ask for the type
+    // second, so that the result can re-use the first input.
+    MOZ_ASSERT(inner->type() == MIRType::Value);
+
+    ensureDefined(inner);
+
+    if (IsFloatingPointType(unbox->type())) {
+        LUnboxFloatingPoint* lir = new(alloc()) LUnboxFloatingPoint(useBox(inner), unbox->type());
+        if (unbox->fallible())
+            assignSnapshot(lir, unbox->bailoutKind());
+        define(lir, unbox);
+        return;
+    }
+
+    // Swap the order we use the box pieces so we can re-use the payload register.
+    LUnbox* lir = new(alloc()) LUnbox;
+    lir->setOperand(0, usePayloadInRegisterAtStart(inner));
+    lir->setOperand(1, useType(inner, LUse::REGISTER));
+
+    if (unbox->fallible())
+        assignSnapshot(lir, unbox->bailoutKind());
+
+    // Types and payloads form two separate intervals. If the type becomes dead
+    // before the payload, it could be used as a Value without the type being
+    // recoverable. Unbox's purpose is to eagerly kill the definition of a type
+    // tag, so keeping both alive (for the purpose of gcmaps) is unappealing.
+    // Instead, we create a new virtual register.
+    defineReuseInput(lir, unbox, 0);
+}
+
+void
+LIRGeneratorARM::visitReturn(MReturn* ret)
+{
+    MDefinition* opd = ret->getOperand(0);
+    MOZ_ASSERT(opd->type() == MIRType::Value);
+
+    LReturn* ins = new(alloc()) LReturn;
+    ins->setOperand(0, LUse(JSReturnReg_Type));
+    ins->setOperand(1, LUse(JSReturnReg_Data));
+    fillBoxUses(ins, 0, opd);
+    add(ins);
+}
+
+void
+LIRGeneratorARM::defineInt64Phi(MPhi* phi, size_t lirIndex)
+{
+    LPhi* low = current->getPhi(lirIndex + INT64LOW_INDEX);
+    LPhi* high = current->getPhi(lirIndex + INT64HIGH_INDEX);
+
+    uint32_t lowVreg = getVirtualRegister();
+
+    phi->setVirtualRegister(lowVreg);
+
+    uint32_t highVreg = getVirtualRegister();
+    MOZ_ASSERT(lowVreg + INT64HIGH_INDEX == highVreg + INT64LOW_INDEX);
+
+    low->setDef(0, LDefinition(lowVreg, LDefinition::INT32));
+    high->setDef(0, LDefinition(highVreg, LDefinition::INT32));
+    annotate(high);
+    annotate(low);
+}
+
+void
+LIRGeneratorARM::lowerInt64PhiInput(MPhi* phi, uint32_t inputPosition, LBlock* block, size_t lirIndex)
+{
+    MDefinition* operand = phi->getOperand(inputPosition);
+    LPhi* low = block->getPhi(lirIndex + INT64LOW_INDEX);
+    LPhi* high = block->getPhi(lirIndex + INT64HIGH_INDEX);
+    low->setOperand(inputPosition, LUse(operand->virtualRegister() + INT64LOW_INDEX, LUse::ANY));
+    high->setOperand(inputPosition, LUse(operand->virtualRegister() + INT64HIGH_INDEX, LUse::ANY));
+}
+
+// x = !y
+void
+LIRGeneratorARM::lowerForALU(LInstructionHelper<1, 1, 0>* ins, MDefinition* mir, MDefinition* input)
+{
+    ins->setOperand(0, ins->snapshot() ? useRegister(input) : useRegisterAtStart(input));
+    define(ins, mir, LDefinition(LDefinition::TypeFrom(mir->type()), LDefinition::REGISTER));
+}
+
+// z = x+y
+void
+LIRGeneratorARM::lowerForALU(LInstructionHelper<1, 2, 0>* ins, MDefinition* mir, MDefinition* lhs, MDefinition* rhs)
+{
+    // Some operations depend on checking inputs after writing the result, e.g.
+    // MulI, but only for bail out paths so useAtStart when no bailouts.
+    ins->setOperand(0, ins->snapshot() ? useRegister(lhs) : useRegisterAtStart(lhs));
+    ins->setOperand(1, ins->snapshot() ? useRegisterOrConstant(rhs) :
+                                         useRegisterOrConstantAtStart(rhs));
+    define(ins, mir, LDefinition(LDefinition::TypeFrom(mir->type()), LDefinition::REGISTER));
+}
+
+void
+LIRGeneratorARM::lowerForALUInt64(LInstructionHelper<INT64_PIECES, 2 * INT64_PIECES, 0>* ins,
+                                  MDefinition* mir, MDefinition* lhs, MDefinition* rhs)
+{
+    ins->setInt64Operand(0, useInt64RegisterAtStart(lhs));
+    ins->setInt64Operand(INT64_PIECES, useInt64OrConstant(rhs));
+    defineInt64ReuseInput(ins, mir, 0);
+}
+
+void
+LIRGeneratorARM::lowerForMulInt64(LMulI64* ins, MMul* mir, MDefinition* lhs, MDefinition* rhs)
+{
+    bool needsTemp = true;
+
+    if (rhs->isConstant()) {
+        int64_t constant = rhs->toConstant()->toInt64();
+        int32_t shift = mozilla::FloorLog2(constant);
+        // See special cases in CodeGeneratorARM::visitMulI64
+        if (constant >= -1 && constant <= 2)
+            needsTemp = false;
+        if (int64_t(1) << shift == constant)
+            needsTemp = false;
+    }
+
+    ins->setInt64Operand(0, useInt64RegisterAtStart(lhs));
+    ins->setInt64Operand(INT64_PIECES, useInt64OrConstant(rhs));
+    if (needsTemp)
+        ins->setTemp(0, temp());
+
+    defineInt64ReuseInput(ins, mir, 0);
+}
+
+void
+LIRGeneratorARM::lowerForFPU(LInstructionHelper<1, 1, 0>* ins, MDefinition* mir, MDefinition* input)
+{
+    ins->setOperand(0, useRegisterAtStart(input));
+    define(ins, mir, LDefinition(LDefinition::TypeFrom(mir->type()), LDefinition::REGISTER));
+}
+
+template<size_t Temps>
+void
+LIRGeneratorARM::lowerForFPU(LInstructionHelper<1, 2, Temps>* ins, MDefinition* mir, MDefinition* lhs, MDefinition* rhs)
+{
+    ins->setOperand(0, useRegisterAtStart(lhs));
+    ins->setOperand(1, useRegisterAtStart(rhs));
+    define(ins, mir, LDefinition(LDefinition::TypeFrom(mir->type()), LDefinition::REGISTER));
+}
+
+template void LIRGeneratorARM::lowerForFPU(LInstructionHelper<1, 2, 0>* ins, MDefinition* mir,
+                                           MDefinition* lhs, MDefinition* rhs);
+template void LIRGeneratorARM::lowerForFPU(LInstructionHelper<1, 2, 1>* ins, MDefinition* mir,
+                                           MDefinition* lhs, MDefinition* rhs);
+
+void
+LIRGeneratorARM::lowerForBitAndAndBranch(LBitAndAndBranch* baab, MInstruction* mir,
+                                         MDefinition* lhs, MDefinition* rhs)
+{
+    baab->setOperand(0, useRegisterAtStart(lhs));
+    baab->setOperand(1, useRegisterOrConstantAtStart(rhs));
+    add(baab, mir);
+}
+
+void
+LIRGeneratorARM::defineUntypedPhi(MPhi* phi, size_t lirIndex)
+{
+    LPhi* type = current->getPhi(lirIndex + VREG_TYPE_OFFSET);
+    LPhi* payload = current->getPhi(lirIndex + VREG_DATA_OFFSET);
+
+    uint32_t typeVreg = getVirtualRegister();
+    phi->setVirtualRegister(typeVreg);
+
+    uint32_t payloadVreg = getVirtualRegister();
+    MOZ_ASSERT(typeVreg + 1 == payloadVreg);
+
+    type->setDef(0, LDefinition(typeVreg, LDefinition::TYPE));
+    payload->setDef(0, LDefinition(payloadVreg, LDefinition::PAYLOAD));
+    annotate(type);
+    annotate(payload);
+}
+
+void
+LIRGeneratorARM::lowerUntypedPhiInput(MPhi* phi, uint32_t inputPosition, LBlock* block, size_t lirIndex)
+{
+    MDefinition* operand = phi->getOperand(inputPosition);
+    LPhi* type = block->getPhi(lirIndex + VREG_TYPE_OFFSET);
+    LPhi* payload = block->getPhi(lirIndex + VREG_DATA_OFFSET);
+    type->setOperand(inputPosition, LUse(operand->virtualRegister() + VREG_TYPE_OFFSET, LUse::ANY));
+    payload->setOperand(inputPosition, LUse(VirtualRegisterOfPayload(operand), LUse::ANY));
+}
+
+void
+LIRGeneratorARM::lowerForShift(LInstructionHelper<1, 2, 0>* ins, MDefinition* mir, MDefinition* lhs, MDefinition* rhs)
+{
+    ins->setOperand(0, useRegister(lhs));
+    ins->setOperand(1, useRegisterOrConstant(rhs));
+    define(ins, mir);
+}
+
+template<size_t Temps>
+void
+LIRGeneratorARM::lowerForShiftInt64(LInstructionHelper<INT64_PIECES, INT64_PIECES + 1, Temps>* ins,
+                                    MDefinition* mir, MDefinition* lhs, MDefinition* rhs)
+{
+    if (mir->isRotate() && !rhs->isConstant())
+        ins->setTemp(0, temp());
+
+    ins->setInt64Operand(0, useInt64RegisterAtStart(lhs));
+    ins->setOperand(INT64_PIECES, useRegisterOrConstant(rhs));
+    defineInt64ReuseInput(ins, mir, 0);
+}
+
+template void LIRGeneratorARM::lowerForShiftInt64(
+    LInstructionHelper<INT64_PIECES, INT64_PIECES+1, 0>* ins, MDefinition* mir,
+    MDefinition* lhs, MDefinition* rhs);
+template void LIRGeneratorARM::lowerForShiftInt64(
+    LInstructionHelper<INT64_PIECES, INT64_PIECES+1, 1>* ins, MDefinition* mir,
+    MDefinition* lhs, MDefinition* rhs);
+
+void
+LIRGeneratorARM::lowerDivI(MDiv* div)
+{
+    if (div->isUnsigned()) {
+        lowerUDiv(div);
+        return;
+    }
+
+    // Division instructions are slow. Division by constant denominators can be
+    // rewritten to use other instructions.
+    if (div->rhs()->isConstant()) {
+        int32_t rhs = div->rhs()->toConstant()->toInt32();
+        // Check for division by a positive power of two, which is an easy and
+        // important case to optimize. Note that other optimizations are also
+        // possible; division by negative powers of two can be optimized in a
+        // similar manner as positive powers of two, and division by other
+        // constants can be optimized by a reciprocal multiplication technique.
+        int32_t shift = FloorLog2(rhs);
+        if (rhs > 0 && 1 << shift == rhs) {
+            LDivPowTwoI* lir = new(alloc()) LDivPowTwoI(useRegisterAtStart(div->lhs()), shift);
+            if (div->fallible())
+                assignSnapshot(lir, Bailout_DoubleOutput);
+            define(lir, div);
+            return;
+        }
+    }
+
+    if (HasIDIV()) {
+        LDivI* lir = new(alloc()) LDivI(useRegister(div->lhs()), useRegister(div->rhs()), temp());
+        if (div->fallible())
+            assignSnapshot(lir, Bailout_DoubleOutput);
+        define(lir, div);
+        return;
+    }
+
+    LSoftDivI* lir = new(alloc()) LSoftDivI(useFixedAtStart(div->lhs(), r0), useFixedAtStart(div->rhs(), r1),
+                                            tempFixed(r1), tempFixed(r2), tempFixed(r3));
+    if (div->fallible())
+        assignSnapshot(lir, Bailout_DoubleOutput);
+    defineFixed(lir, div, LAllocation(AnyRegister(r0)));
+}
+
+void
+LIRGeneratorARM::lowerMulI(MMul* mul, MDefinition* lhs, MDefinition* rhs)
+{
+    LMulI* lir = new(alloc()) LMulI;
+    if (mul->fallible())
+        assignSnapshot(lir, Bailout_DoubleOutput);
+    lowerForALU(lir, mul, lhs, rhs);
+}
+
+void
+LIRGeneratorARM::lowerModI(MMod* mod)
+{
+    if (mod->isUnsigned()) {
+        lowerUMod(mod);
+        return;
+    }
+
+    if (mod->rhs()->isConstant()) {
+        int32_t rhs = mod->rhs()->toConstant()->toInt32();
+        int32_t shift = FloorLog2(rhs);
+        if (rhs > 0 && 1 << shift == rhs) {
+            LModPowTwoI* lir = new(alloc()) LModPowTwoI(useRegister(mod->lhs()), shift);
+            if (mod->fallible())
+                assignSnapshot(lir, Bailout_DoubleOutput);
+            define(lir, mod);
+            return;
+        }
+        if (shift < 31 && (1 << (shift+1)) - 1 == rhs) {
+            MOZ_ASSERT(rhs);
+            LModMaskI* lir = new(alloc()) LModMaskI(useRegister(mod->lhs()), temp(), temp(), shift+1);
+            if (mod->fallible())
+                assignSnapshot(lir, Bailout_DoubleOutput);
+            define(lir, mod);
+            return;
+        }
+    }
+
+    if (HasIDIV()) {
+        LModI* lir = new(alloc()) LModI(useRegister(mod->lhs()), useRegister(mod->rhs()), temp());
+        if (mod->fallible())
+            assignSnapshot(lir, Bailout_DoubleOutput);
+        define(lir, mod);
+        return;
+    }
+
+    LSoftModI* lir = new(alloc()) LSoftModI(useFixedAtStart(mod->lhs(), r0), useFixedAtStart(mod->rhs(), r1),
+                                            tempFixed(r0), tempFixed(r2), tempFixed(r3),
+                                            temp(LDefinition::GENERAL));
+    if (mod->fallible())
+        assignSnapshot(lir, Bailout_DoubleOutput);
+    defineFixed(lir, mod, LAllocation(AnyRegister(r1)));
+}
+
+void
+LIRGeneratorARM::lowerDivI64(MDiv* div)
+{
+    if (div->isUnsigned()) {
+        lowerUDivI64(div);
+        return;
+    }
+
+    LDivOrModI64* lir = new(alloc()) LDivOrModI64(useInt64RegisterAtStart(div->lhs()),
+                                                  useInt64RegisterAtStart(div->rhs()));
+    defineReturn(lir, div);
+}
+
+void
+LIRGeneratorARM::lowerModI64(MMod* mod)
+{
+    if (mod->isUnsigned()) {
+        lowerUModI64(mod);
+        return;
+    }
+
+    LDivOrModI64* lir = new(alloc()) LDivOrModI64(useInt64RegisterAtStart(mod->lhs()),
+                                                  useInt64RegisterAtStart(mod->rhs()));
+    defineReturn(lir, mod);
+}
+
+void
+LIRGeneratorARM::lowerUDivI64(MDiv* div)
+{
+    LUDivOrModI64* lir = new(alloc()) LUDivOrModI64(useInt64RegisterAtStart(div->lhs()),
+                                                    useInt64RegisterAtStart(div->rhs()));
+    defineReturn(lir, div);
+}
+
+void
+LIRGeneratorARM::lowerUModI64(MMod* mod)
+{
+    LUDivOrModI64* lir = new(alloc()) LUDivOrModI64(useInt64RegisterAtStart(mod->lhs()),
+                                                    useInt64RegisterAtStart(mod->rhs()));
+    defineReturn(lir, mod);
+}
+
+void
+LIRGeneratorARM::visitPowHalf(MPowHalf* ins)
+{
+    MDefinition* input = ins->input();
+    MOZ_ASSERT(input->type() == MIRType::Double);
+    LPowHalfD* lir = new(alloc()) LPowHalfD(useRegisterAtStart(input));
+    defineReuseInput(lir, ins, 0);
+}
+
+LTableSwitch*
+LIRGeneratorARM::newLTableSwitch(const LAllocation& in, const LDefinition& inputCopy,
+                                       MTableSwitch* tableswitch)
+{
+    return new(alloc()) LTableSwitch(in, inputCopy, tableswitch);
+}
+
+LTableSwitchV*
+LIRGeneratorARM::newLTableSwitchV(MTableSwitch* tableswitch)
+{
+    return new(alloc()) LTableSwitchV(useBox(tableswitch->getOperand(0)),
+                                      temp(), tempDouble(), tableswitch);
+}
+
+void
+LIRGeneratorARM::visitGuardShape(MGuardShape* ins)
+{
+    MOZ_ASSERT(ins->object()->type() == MIRType::Object);
+
+    LDefinition tempObj = temp(LDefinition::OBJECT);
+    LGuardShape* guard = new(alloc()) LGuardShape(useRegister(ins->object()), tempObj);
+    assignSnapshot(guard, ins->bailoutKind());
+    add(guard, ins);
+    redefine(ins, ins->object());
+}
+
+void
+LIRGeneratorARM::visitGuardObjectGroup(MGuardObjectGroup* ins)
+{
+    MOZ_ASSERT(ins->object()->type() == MIRType::Object);
+
+    LDefinition tempObj = temp(LDefinition::OBJECT);
+    LGuardObjectGroup* guard = new(alloc()) LGuardObjectGroup(useRegister(ins->object()), tempObj);
+    assignSnapshot(guard, ins->bailoutKind());
+    add(guard, ins);
+    redefine(ins, ins->object());
+}
+
+void
+LIRGeneratorARM::lowerUrshD(MUrsh* mir)
+{
+    MDefinition* lhs = mir->lhs();
+    MDefinition* rhs = mir->rhs();
+
+    MOZ_ASSERT(lhs->type() == MIRType::Int32);
+    MOZ_ASSERT(rhs->type() == MIRType::Int32);
+
+    LUrshD* lir = new(alloc()) LUrshD(useRegister(lhs), useRegisterOrConstant(rhs), temp());
+    define(lir, mir);
+}
+
+void
+LIRGeneratorARM::visitWasmSelect(MWasmSelect* ins)
+{
+    if (ins->type() == MIRType::Int64) {
+        auto* lir = new(alloc()) LWasmSelectI64(useInt64RegisterAtStart(ins->trueExpr()),
+                                                useInt64(ins->falseExpr()),
+                                                useRegister(ins->condExpr()));
+
+        defineInt64ReuseInput(lir, ins, LWasmSelectI64::TrueExprIndex);
+        return;
+    }
+
+    auto* lir = new(alloc()) LWasmSelect(useRegisterAtStart(ins->trueExpr()),
+                                         useRegister(ins->falseExpr()),
+                                         useRegister(ins->condExpr()));
+
+    defineReuseInput(lir, ins, LWasmSelect::TrueExprIndex);
+}
+
+void
+LIRGeneratorARM::visitAsmJSNeg(MAsmJSNeg* ins)
+{
+    if (ins->type() == MIRType::Int32) {
+        define(new(alloc()) LNegI(useRegisterAtStart(ins->input())), ins);
+    } else if (ins->type() == MIRType::Float32) {
+        define(new(alloc()) LNegF(useRegisterAtStart(ins->input())), ins);
+    } else {
+        MOZ_ASSERT(ins->type() == MIRType::Double);
+        define(new(alloc()) LNegD(useRegisterAtStart(ins->input())), ins);
+    }
+}
+
+void
+LIRGeneratorARM::lowerUDiv(MDiv* div)
+{
+    MDefinition* lhs = div->getOperand(0);
+    MDefinition* rhs = div->getOperand(1);
+
+    if (HasIDIV()) {
+        LUDiv* lir = new(alloc()) LUDiv;
+        lir->setOperand(0, useRegister(lhs));
+        lir->setOperand(1, useRegister(rhs));
+        if (div->fallible())
+            assignSnapshot(lir, Bailout_DoubleOutput);
+        define(lir, div);
+    } else {
+        LSoftUDivOrMod* lir = new(alloc()) LSoftUDivOrMod(useFixedAtStart(lhs, r0), useFixedAtStart(rhs, r1),
+                                                          tempFixed(r1), tempFixed(r2), tempFixed(r3));
+        if (div->fallible())
+            assignSnapshot(lir, Bailout_DoubleOutput);
+        defineFixed(lir, div, LAllocation(AnyRegister(r0)));
+    }
+}
+
+void
+LIRGeneratorARM::lowerUMod(MMod* mod)
+{
+    MDefinition* lhs = mod->getOperand(0);
+    MDefinition* rhs = mod->getOperand(1);
+
+    if (HasIDIV()) {
+        LUMod* lir = new(alloc()) LUMod;
+        lir->setOperand(0, useRegister(lhs));
+        lir->setOperand(1, useRegister(rhs));
+        if (mod->fallible())
+            assignSnapshot(lir, Bailout_DoubleOutput);
+        define(lir, mod);
+    } else {
+        LSoftUDivOrMod* lir = new(alloc()) LSoftUDivOrMod(useFixedAtStart(lhs, r0), useFixedAtStart(rhs, r1),
+                                                          tempFixed(r0), tempFixed(r2), tempFixed(r3));
+        if (mod->fallible())
+            assignSnapshot(lir, Bailout_DoubleOutput);
+        defineFixed(lir, mod, LAllocation(AnyRegister(r1)));
+    }
+}
+
+void
+LIRGeneratorARM::visitWasmUnsignedToDouble(MWasmUnsignedToDouble* ins)
+{
+    MOZ_ASSERT(ins->input()->type() == MIRType::Int32);
+    LWasmUint32ToDouble* lir = new(alloc()) LWasmUint32ToDouble(useRegisterAtStart(ins->input()));
+    define(lir, ins);
+}
+
+void
+LIRGeneratorARM::visitWasmUnsignedToFloat32(MWasmUnsignedToFloat32* ins)
+{
+    MOZ_ASSERT(ins->input()->type() == MIRType::Int32);
+    LWasmUint32ToFloat32* lir = new(alloc()) LWasmUint32ToFloat32(useRegisterAtStart(ins->input()));
+    define(lir, ins);
+}
+
+void
+LIRGeneratorARM::visitWasmLoad(MWasmLoad* ins)
+{
+    MDefinition* base = ins->base();
+    MOZ_ASSERT(base->type() == MIRType::Int32);
+
+    LAllocation ptr = useRegisterAtStart(base);
+
+    if (ins->access().isUnaligned()) {
+        // Unaligned access expected! Revert to a byte load.
+        LDefinition ptrCopy = tempCopy(base, 0);
+
+        LDefinition noTemp = LDefinition::BogusTemp();
+        if (ins->type() == MIRType::Int64) {
+            auto* lir = new(alloc()) LWasmUnalignedLoadI64(ptr, ptrCopy, temp(), noTemp, noTemp);
+            defineInt64(lir, ins);
+            return;
+        }
+
+        LDefinition temp2 = noTemp;
+        LDefinition temp3 = noTemp;
+        if (IsFloatingPointType(ins->type())) {
+            // For putting the low value in a GPR.
+            temp2 = temp();
+            // For putting the high value in a GPR.
+            if (ins->type() == MIRType::Double)
+                temp3 = temp();
+        }
+
+        auto* lir = new(alloc()) LWasmUnalignedLoad(ptr, ptrCopy, temp(), temp2, temp3);
+        define(lir, ins);
+        return;
+    }
+
+    if (ins->type() == MIRType::Int64) {
+        auto* lir = new(alloc()) LWasmLoadI64(ptr);
+        if (ins->access().offset() || ins->access().type() == Scalar::Int64)
+            lir->setTemp(0, tempCopy(base, 0));
+        defineInt64(lir, ins);
+        return;
+    }
+
+    auto* lir = new(alloc()) LWasmLoad(ptr);
+    if (ins->access().offset())
+        lir->setTemp(0, tempCopy(base, 0));
+
+    define(lir, ins);
+}
+
+void
+LIRGeneratorARM::visitWasmStore(MWasmStore* ins)
+{
+    MDefinition* base = ins->base();
+    MOZ_ASSERT(base->type() == MIRType::Int32);
+
+    LAllocation ptr = useRegisterAtStart(base);
+
+    if (ins->access().isUnaligned()) {
+        // Unaligned access expected! Revert to a byte store.
+        LDefinition ptrCopy = tempCopy(base, 0);
+
+        MIRType valueType = ins->value()->type();
+        if (valueType == MIRType::Int64) {
+            LInt64Allocation value = useInt64RegisterAtStart(ins->value());
+            auto* lir = new(alloc()) LWasmUnalignedStoreI64(ptr, value, ptrCopy, temp());
+            add(lir, ins);
+            return;
+        }
+
+        LAllocation value = useRegisterAtStart(ins->value());
+        LDefinition valueHelper = IsFloatingPointType(valueType)
+                                  ? temp()             // to do a FPU -> GPR move.
+                                  : tempCopy(base, 1); // to clobber the value.
+
+        auto* lir = new(alloc()) LWasmUnalignedStore(ptr, value, ptrCopy, valueHelper);
+        add(lir, ins);
+        return;
+    }
+
+    if (ins->value()->type() == MIRType::Int64) {
+        LInt64Allocation value = useInt64RegisterAtStart(ins->value());
+        auto* lir = new(alloc()) LWasmStoreI64(ptr, value);
+        if (ins->access().offset() || ins->access().type() == Scalar::Int64)
+            lir->setTemp(0, tempCopy(base, 0));
+        add(lir, ins);
+        return;
+    }
+
+    LAllocation value = useRegisterAtStart(ins->value());
+    auto* lir = new(alloc()) LWasmStore(ptr, value);
+
+    if (ins->access().offset())
+        lir->setTemp(0, tempCopy(base, 0));
+
+    add(lir, ins);
+}
+
+void
+LIRGeneratorARM::visitAsmJSLoadHeap(MAsmJSLoadHeap* ins)
+{
+    MOZ_ASSERT(ins->offset() == 0);
+
+    MDefinition* base = ins->base();
+    MOZ_ASSERT(base->type() == MIRType::Int32);
+
+    // For the ARM it is best to keep the 'base' in a register if a bounds check is needed.
+    LAllocation baseAlloc;
+    if (base->isConstant() && !ins->needsBoundsCheck()) {
+        // A bounds check is only skipped for a positive index.
+        MOZ_ASSERT(base->toConstant()->toInt32() >= 0);
+        baseAlloc = LAllocation(base->toConstant());
+    } else {
+        baseAlloc = useRegisterAtStart(base);
+    }
+
+    define(new(alloc()) LAsmJSLoadHeap(baseAlloc), ins);
+}
+
+void
+LIRGeneratorARM::visitAsmJSStoreHeap(MAsmJSStoreHeap* ins)
+{
+    MOZ_ASSERT(ins->offset() == 0);
+
+    MDefinition* base = ins->base();
+    MOZ_ASSERT(base->type() == MIRType::Int32);
+    LAllocation baseAlloc;
+
+    if (base->isConstant() && !ins->needsBoundsCheck()) {
+        MOZ_ASSERT(base->toConstant()->toInt32() >= 0);
+        baseAlloc = LAllocation(base->toConstant());
+    } else {
+        baseAlloc = useRegisterAtStart(base);
+    }
+
+    add(new(alloc()) LAsmJSStoreHeap(baseAlloc, useRegisterAtStart(ins->value())), ins);
+}
+
+void
+LIRGeneratorARM::lowerTruncateDToInt32(MTruncateToInt32* ins)
+{
+    MDefinition* opd = ins->input();
+    MOZ_ASSERT(opd->type() == MIRType::Double);
+
+    define(new(alloc()) LTruncateDToInt32(useRegister(opd), LDefinition::BogusTemp()), ins);
+}
+
+void
+LIRGeneratorARM::lowerTruncateFToInt32(MTruncateToInt32* ins)
+{
+    MDefinition* opd = ins->input();
+    MOZ_ASSERT(opd->type() == MIRType::Float32);
+
+    define(new(alloc()) LTruncateFToInt32(useRegister(opd), LDefinition::BogusTemp()), ins);
+}
+
+void
+LIRGeneratorARM::visitStoreTypedArrayElementStatic(MStoreTypedArrayElementStatic* ins)
+{
+    MOZ_CRASH("NYI");
+}
+
+void
+LIRGeneratorARM::visitAtomicExchangeTypedArrayElement(MAtomicExchangeTypedArrayElement* ins)
+{
+    MOZ_ASSERT(HasLDSTREXBHD());
+    MOZ_ASSERT(ins->arrayType() <= Scalar::Uint32);
+
+    MOZ_ASSERT(ins->elements()->type() == MIRType::Elements);
+    MOZ_ASSERT(ins->index()->type() == MIRType::Int32);
+
+    const LUse elements = useRegister(ins->elements());
+    const LAllocation index = useRegisterOrConstant(ins->index());
+
+    // If the target is a floating register then we need a temp at the
+    // CodeGenerator level for creating the result.
+
+    const LAllocation value = useRegister(ins->value());
+    LDefinition tempDef = LDefinition::BogusTemp();
+    if (ins->arrayType() == Scalar::Uint32) {
+        MOZ_ASSERT(ins->type() == MIRType::Double);
+        tempDef = temp();
+    }
+
+    LAtomicExchangeTypedArrayElement* lir =
+        new(alloc()) LAtomicExchangeTypedArrayElement(elements, index, value, tempDef);
+
+    define(lir, ins);
+}
+
+void
+LIRGeneratorARM::visitAtomicTypedArrayElementBinop(MAtomicTypedArrayElementBinop* ins)
+{
+    MOZ_ASSERT(ins->arrayType() != Scalar::Uint8Clamped);
+    MOZ_ASSERT(ins->arrayType() != Scalar::Float32);
+    MOZ_ASSERT(ins->arrayType() != Scalar::Float64);
+
+    MOZ_ASSERT(ins->elements()->type() == MIRType::Elements);
+    MOZ_ASSERT(ins->index()->type() == MIRType::Int32);
+
+    const LUse elements = useRegister(ins->elements());
+    const LAllocation index = useRegisterOrConstant(ins->index());
+    const LAllocation value = useRegister(ins->value());
+
+    if (!ins->hasUses()) {
+        LAtomicTypedArrayElementBinopForEffect* lir =
+            new(alloc()) LAtomicTypedArrayElementBinopForEffect(elements, index, value,
+                                                                /* flagTemp= */ temp());
+        add(lir, ins);
+        return;
+    }
+
+    // For a Uint32Array with a known double result we need a temp for
+    // the intermediate output.
+    //
+    // Optimization opportunity (bug 1077317): We can do better by
+    // allowing 'value' to remain as an imm32 if it is small enough to
+    // fit in an instruction.
+
+    LDefinition flagTemp = temp();
+    LDefinition outTemp = LDefinition::BogusTemp();
+
+    if (ins->arrayType() == Scalar::Uint32 && IsFloatingPointType(ins->type()))
+        outTemp = temp();
+
+    // On arm, map flagTemp to temp1 and outTemp to temp2, at least for now.
+
+    LAtomicTypedArrayElementBinop* lir =
+        new(alloc()) LAtomicTypedArrayElementBinop(elements, index, value, flagTemp, outTemp);
+    define(lir, ins);
+}
+
+void
+LIRGeneratorARM::visitCompareExchangeTypedArrayElement(MCompareExchangeTypedArrayElement* ins)
+{
+    MOZ_ASSERT(ins->arrayType() != Scalar::Float32);
+    MOZ_ASSERT(ins->arrayType() != Scalar::Float64);
+
+    MOZ_ASSERT(ins->elements()->type() == MIRType::Elements);
+    MOZ_ASSERT(ins->index()->type() == MIRType::Int32);
+
+    const LUse elements = useRegister(ins->elements());
+    const LAllocation index = useRegisterOrConstant(ins->index());
+
+    // If the target is a floating register then we need a temp at the
+    // CodeGenerator level for creating the result.
+    //
+    // Optimization opportunity (bug 1077317): We could do better by
+    // allowing oldval to remain an immediate, if it is small enough
+    // to fit in an instruction.
+
+    const LAllocation newval = useRegister(ins->newval());
+    const LAllocation oldval = useRegister(ins->oldval());
+    LDefinition tempDef = LDefinition::BogusTemp();
+    if (ins->arrayType() == Scalar::Uint32 && IsFloatingPointType(ins->type()))
+        tempDef = temp();
+
+    LCompareExchangeTypedArrayElement* lir =
+        new(alloc()) LCompareExchangeTypedArrayElement(elements, index, oldval, newval, tempDef);
+
+    define(lir, ins);
+}
+
+void
+LIRGeneratorARM::visitAsmJSCompareExchangeHeap(MAsmJSCompareExchangeHeap* ins)
+{
+    MOZ_ASSERT(ins->access().type() < Scalar::Float32);
+    MOZ_ASSERT(ins->access().offset() == 0);
+
+    MDefinition* base = ins->base();
+    MOZ_ASSERT(base->type() == MIRType::Int32);
+
+    if (byteSize(ins->access().type()) != 4 && !HasLDSTREXBHD()) {
+        LAsmJSCompareExchangeCallout* lir =
+            new(alloc()) LAsmJSCompareExchangeCallout(useRegisterAtStart(base),
+                                                      useRegisterAtStart(ins->oldValue()),
+                                                      useRegisterAtStart(ins->newValue()),
+                                                      useFixed(ins->tls(), WasmTlsReg),
+                                                      temp(), temp());
+        defineReturn(lir, ins);
+        return;
+    }
+
+    LAsmJSCompareExchangeHeap* lir =
+        new(alloc()) LAsmJSCompareExchangeHeap(useRegister(base),
+                                               useRegister(ins->oldValue()),
+                                               useRegister(ins->newValue()));
+
+    define(lir, ins);
+}
+
+void
+LIRGeneratorARM::visitAsmJSAtomicExchangeHeap(MAsmJSAtomicExchangeHeap* ins)
+{
+    MOZ_ASSERT(ins->base()->type() == MIRType::Int32);
+    MOZ_ASSERT(ins->access().type() < Scalar::Float32);
+    MOZ_ASSERT(ins->access().offset() == 0);
+
+    const LAllocation base = useRegisterAtStart(ins->base());
+    const LAllocation value = useRegisterAtStart(ins->value());
+
+    if (byteSize(ins->access().type()) < 4 && !HasLDSTREXBHD()) {
+        // Call out on ARMv6.
+        defineReturn(new(alloc()) LAsmJSAtomicExchangeCallout(base, value,
+                                                              useFixed(ins->tls(), WasmTlsReg),
+                                                              temp(), temp()), ins);
+        return;
+    }
+
+    define(new(alloc()) LAsmJSAtomicExchangeHeap(base, value), ins);
+}
+
+void
+LIRGeneratorARM::visitAsmJSAtomicBinopHeap(MAsmJSAtomicBinopHeap* ins)
+{
+    MOZ_ASSERT(ins->access().type() < Scalar::Float32);
+    MOZ_ASSERT(ins->access().offset() == 0);
+
+    MDefinition* base = ins->base();
+    MOZ_ASSERT(base->type() == MIRType::Int32);
+
+    if (byteSize(ins->access().type()) != 4 && !HasLDSTREXBHD()) {
+        LAsmJSAtomicBinopCallout* lir =
+            new(alloc()) LAsmJSAtomicBinopCallout(useRegisterAtStart(base),
+                                                  useRegisterAtStart(ins->value()),
+                                                  useFixed(ins->tls(), WasmTlsReg),
+                                                  temp(), temp());
+        defineReturn(lir, ins);
+        return;
+    }
+
+    if (!ins->hasUses()) {
+        LAsmJSAtomicBinopHeapForEffect* lir =
+            new(alloc()) LAsmJSAtomicBinopHeapForEffect(useRegister(base),
+                                                        useRegister(ins->value()),
+                                                        /* flagTemp= */ temp());
+        add(lir, ins);
+        return;
+    }
+
+    LAsmJSAtomicBinopHeap* lir =
+        new(alloc()) LAsmJSAtomicBinopHeap(useRegister(base),
+                                           useRegister(ins->value()),
+                                           /* temp = */ LDefinition::BogusTemp(),
+                                           /* flagTemp= */ temp());
+    define(lir, ins);
+}
+
+void
+LIRGeneratorARM::visitSubstr(MSubstr* ins)
+{
+    LSubstr* lir = new (alloc()) LSubstr(useRegister(ins->string()),
+                                         useRegister(ins->begin()),
+                                         useRegister(ins->length()),
+                                         temp(),
+                                         temp(),
+                                         tempByteOpRegister());
+    define(lir, ins);
+    assignSafepoint(lir, ins);
+}
+
+void
+LIRGeneratorARM::visitRandom(MRandom* ins)
+{
+    LRandom *lir = new(alloc()) LRandom(temp(),
+                                        temp(),
+                                        temp(),
+                                        temp(),
+                                        temp());
+    defineFixed(lir, ins, LFloatReg(ReturnDoubleReg));
+}
+
+void
+LIRGeneratorARM::visitWasmTruncateToInt64(MWasmTruncateToInt64* ins)
+{
+    MDefinition* opd = ins->input();
+    MOZ_ASSERT(opd->type() == MIRType::Double || opd->type() == MIRType::Float32);
+
+    defineReturn(new(alloc()) LWasmTruncateToInt64(useRegisterAtStart(opd)), ins);
+}
+
+void
+LIRGeneratorARM::visitInt64ToFloatingPoint(MInt64ToFloatingPoint* ins)
+{
+    MOZ_ASSERT(ins->type() == MIRType::Double || ins->type() == MIRType::Float32);
+
+    auto lir = new(alloc()) LInt64ToFloatingPointCall();
+    lir->setInt64Operand(0, useInt64RegisterAtStart(ins->input()));
+    defineReturn(lir, ins);
+}
+
+void
+LIRGeneratorARM::visitCopySign(MCopySign* ins)
+{
+    MDefinition* lhs = ins->lhs();
+    MDefinition* rhs = ins->rhs();
+
+    MOZ_ASSERT(IsFloatingPointType(lhs->type()));
+    MOZ_ASSERT(lhs->type() == rhs->type());
+    MOZ_ASSERT(lhs->type() == ins->type());
+
+    LInstructionHelper<1, 2, 2>* lir;
+    if (lhs->type() == MIRType::Double)
+        lir = new(alloc()) LCopySignD();
+    else
+        lir = new(alloc()) LCopySignF();
+
+    lir->setTemp(0, temp());
+    lir->setTemp(1, temp());
+
+    lowerForFPU(lir, ins, lhs, rhs);
+}
+
+void
+LIRGeneratorARM::visitExtendInt32ToInt64(MExtendInt32ToInt64* ins)
+{
+    auto* lir = new(alloc()) LExtendInt32ToInt64(useRegisterAtStart(ins->input()));
+    defineInt64(lir, ins);
+
+    LDefinition def(LDefinition::GENERAL, LDefinition::MUST_REUSE_INPUT);
+    def.setReusedInput(0);
+    def.setVirtualRegister(ins->virtualRegister());
+
+    lir->setDef(0, def);
+}
diff --git a/js/src/jit/arm/Lowering-arm.h b/js/src/jit/arm/Lowering-arm.h
new file mode 100644
index 0000000000..d66ef8a22b
--- /dev/null
+++ b/js/src/jit/arm/Lowering-arm.h
@@ -0,0 +1,132 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef jit_arm_Lowering_arm_h
+#define jit_arm_Lowering_arm_h
+
+#include "jit/shared/Lowering-shared.h"
+
+namespace js {
+namespace jit {
+
+class LIRGeneratorARM : public LIRGeneratorShared
+{
+  public:
+    LIRGeneratorARM(MIRGenerator* gen, MIRGraph& graph, LIRGraph& lirGraph)
+      : LIRGeneratorShared(gen, graph, lirGraph)
+    { }
+
+  protected:
+    // Returns a box allocation with type set to reg1 and payload set to reg2.
+    LBoxAllocation useBoxFixed(MDefinition* mir, Register reg1, Register reg2,
+                               bool useAtStart = false);
+
+    // x86 has constraints on what registers can be formatted for 1-byte
+    // stores and loads; on ARM all registers are okay.
+    LAllocation useByteOpRegister(MDefinition* mir);
+    LAllocation useByteOpRegisterAtStart(MDefinition* mir);
+    LAllocation useByteOpRegisterOrNonDoubleConstant(MDefinition* mir);
+    LDefinition tempByteOpRegister();
+
+    inline LDefinition tempToUnbox() {
+        return LDefinition::BogusTemp();
+    }
+
+    bool needTempForPostBarrier() { return false; }
+
+    void lowerUntypedPhiInput(MPhi* phi, uint32_t inputPosition, LBlock* block, size_t lirIndex);
+    void defineUntypedPhi(MPhi* phi, size_t lirIndex);
+    void lowerInt64PhiInput(MPhi* phi, uint32_t inputPosition, LBlock* block, size_t lirIndex);
+    void defineInt64Phi(MPhi* phi, size_t lirIndex);
+
+    void lowerForShift(LInstructionHelper<1, 2, 0>* ins, MDefinition* mir, MDefinition* lhs,
+                       MDefinition* rhs);
+    void lowerUrshD(MUrsh* mir);
+
+    void lowerForALU(LInstructionHelper<1, 1, 0>* ins, MDefinition* mir,
+                     MDefinition* input);
+    void lowerForALU(LInstructionHelper<1, 2, 0>* ins, MDefinition* mir,
+                     MDefinition* lhs, MDefinition* rhs);
+
+    void lowerForALUInt64(LInstructionHelper<INT64_PIECES, 2 * INT64_PIECES, 0>* ins,
+                          MDefinition* mir, MDefinition* lhs, MDefinition* rhs);
+    void lowerForMulInt64(LMulI64* ins, MMul* mir, MDefinition* lhs, MDefinition* rhs);
+    template<size_t Temps>
+    void lowerForShiftInt64(LInstructionHelper<INT64_PIECES, INT64_PIECES + 1, Temps>* ins,
+                            MDefinition* mir, MDefinition* lhs, MDefinition* rhs);
+
+    void lowerForFPU(LInstructionHelper<1, 1, 0>* ins, MDefinition* mir,
+                     MDefinition* src);
+    template<size_t Temps>
+    void lowerForFPU(LInstructionHelper<1, 2, Temps>* ins, MDefinition* mir,
+                     MDefinition* lhs, MDefinition* rhs);
+
+    void lowerForCompIx4(LSimdBinaryCompIx4* ins, MSimdBinaryComp* mir,
+                         MDefinition* lhs, MDefinition* rhs)
+    {
+        return lowerForFPU(ins, mir, lhs, rhs);
+    }
+    void lowerForCompFx4(LSimdBinaryCompFx4* ins, MSimdBinaryComp* mir,
+                         MDefinition* lhs, MDefinition* rhs)
+    {
+        return lowerForFPU(ins, mir, lhs, rhs);
+    }
+
+    void lowerForBitAndAndBranch(LBitAndAndBranch* baab, MInstruction* mir,
+                                 MDefinition* lhs, MDefinition* rhs);
+    void lowerTruncateDToInt32(MTruncateToInt32* ins);
+    void lowerTruncateFToInt32(MTruncateToInt32* ins);
+    void lowerDivI(MDiv* div);
+    void lowerModI(MMod* mod);
+    void lowerDivI64(MDiv* div);
+    void lowerModI64(MMod* mod);
+    void lowerUDivI64(MDiv* div);
+    void lowerUModI64(MMod* mod);
+    void lowerMulI(MMul* mul, MDefinition* lhs, MDefinition* rhs);
+    void lowerUDiv(MDiv* div);
+    void lowerUMod(MMod* mod);
+    void visitPowHalf(MPowHalf* ins);
+    void visitAsmJSNeg(MAsmJSNeg* ins);
+
+    LTableSwitch* newLTableSwitch(const LAllocation& in, const LDefinition& inputCopy,
+                                  MTableSwitch* ins);
+    LTableSwitchV* newLTableSwitchV(MTableSwitch* ins);
+
+  public:
+    void visitBox(MBox* box);
+    void visitUnbox(MUnbox* unbox);
+    void visitReturn(MReturn* ret);
+    void lowerPhi(MPhi* phi);
+    void visitGuardShape(MGuardShape* ins);
+    void visitGuardObjectGroup(MGuardObjectGroup* ins);
+    void visitWasmSelect(MWasmSelect* ins);
+    void visitWasmUnsignedToDouble(MWasmUnsignedToDouble* ins);
+    void visitWasmUnsignedToFloat32(MWasmUnsignedToFloat32* ins);
+    void visitWasmLoad(MWasmLoad* ins);
+    void visitWasmStore(MWasmStore* ins);
+    void visitAsmJSLoadHeap(MAsmJSLoadHeap* ins);
+    void visitAsmJSStoreHeap(MAsmJSStoreHeap* ins);
+    void visitAsmJSCompareExchangeHeap(MAsmJSCompareExchangeHeap* ins);
+    void visitAsmJSAtomicExchangeHeap(MAsmJSAtomicExchangeHeap* ins);
+    void visitAsmJSAtomicBinopHeap(MAsmJSAtomicBinopHeap* ins);
+    void visitStoreTypedArrayElementStatic(MStoreTypedArrayElementStatic* ins);
+    void visitCompareExchangeTypedArrayElement(MCompareExchangeTypedArrayElement* ins);
+    void visitAtomicExchangeTypedArrayElement(MAtomicExchangeTypedArrayElement* ins);
+    void visitAtomicTypedArrayElementBinop(MAtomicTypedArrayElementBinop* ins);
+    void visitSubstr(MSubstr* ins);
+    void visitRandom(MRandom* ins);
+    void visitWasmTruncateToInt64(MWasmTruncateToInt64* ins);
+    void visitInt64ToFloatingPoint(MInt64ToFloatingPoint* ins);
+    void visitCopySign(MCopySign* ins);
+    void visitExtendInt32ToInt64(MExtendInt32ToInt64* ins);
+};
+
+typedef LIRGeneratorARM LIRGeneratorSpecific;
+
+} // namespace jit
+} // namespace js
+
+#endif /* jit_arm_Lowering_arm_h */
diff --git a/js/src/jit/arm/MacroAssembler-arm-inl.h b/js/src/jit/arm/MacroAssembler-arm-inl.h
new file mode 100644
index 0000000000..1b71dfb7f2
--- /dev/null
+++ b/js/src/jit/arm/MacroAssembler-arm-inl.h
@@ -0,0 +1,2143 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef jit_arm_MacroAssembler_arm_inl_h
+#define jit_arm_MacroAssembler_arm_inl_h
+
+#include "jit/arm/MacroAssembler-arm.h"
+
+namespace js {
+namespace jit {
+
+//{{{ check_macroassembler_style
+
+void
+MacroAssembler::move64(Register64 src, Register64 dest)
+{
+    move32(src.low, dest.low);
+    move32(src.high, dest.high);
+}
+
+void
+MacroAssembler::move64(Imm64 imm, Register64 dest)
+{
+    move32(Imm32(imm.value & 0xFFFFFFFFL), dest.low);
+    move32(Imm32((imm.value >> 32) & 0xFFFFFFFFL), dest.high);
+}
+
+void
+MacroAssembler::moveFloat32ToGPR(FloatRegister src, Register dest)
+{
+    ma_vxfer(src, dest);
+}
+
+void
+MacroAssembler::moveGPRToFloat32(Register src, FloatRegister dest)
+{
+    ma_vxfer(src, dest);
+}
+
+void
+MacroAssembler::move8SignExtend(Register src, Register dest)
+{
+    as_sxtb(dest, src, 0);
+}
+
+void
+MacroAssembler::move16SignExtend(Register src, Register dest)
+{
+    as_sxth(dest, src, 0);
+}
+
+// ===============================================================
+// Logical instructions
+
+void
+MacroAssembler::not32(Register reg)
+{
+    ma_mvn(reg, reg);
+}
+
+void
+MacroAssembler::and32(Register src, Register dest)
+{
+    ma_and(src, dest, SetCC);
+}
+
+void
+MacroAssembler::and32(Imm32 imm, Register dest)
+{
+    ScratchRegisterScope scratch(*this);
+    ma_and(imm, dest, scratch, SetCC);
+}
+
+void
+MacroAssembler::and32(Imm32 imm, const Address& dest)
+{
+    ScratchRegisterScope scratch(*this);
+    SecondScratchRegisterScope scratch2(*this);
+
+    ma_ldr(dest, scratch, scratch2);
+    ma_and(imm, scratch, scratch2);
+    ma_str(scratch, dest, scratch2);
+}
+
+void
+MacroAssembler::and32(const Address& src, Register dest)
+{
+    ScratchRegisterScope scratch(*this);
+    SecondScratchRegisterScope scratch2(*this);
+
+    ma_ldr(src, scratch, scratch2);
+    ma_and(scratch, dest, SetCC);
+}
+
+void
+MacroAssembler::andPtr(Register src, Register dest)
+{
+    ma_and(src, dest);
+}
+
+void
+MacroAssembler::andPtr(Imm32 imm, Register dest)
+{
+    ScratchRegisterScope scratch(*this);
+    ma_and(imm, dest, scratch);
+}
+
+void
+MacroAssembler::and64(Imm64 imm, Register64 dest)
+{
+    if (imm.low().value != int32_t(0xFFFFFFFF))
+        and32(imm.low(), dest.low);
+    if (imm.hi().value != int32_t(0xFFFFFFFF))
+        and32(imm.hi(), dest.high);
+}
+
+void
+MacroAssembler::or64(Imm64 imm, Register64 dest)
+{
+    if (imm.low().value)
+        or32(imm.low(), dest.low);
+    if (imm.hi().value)
+        or32(imm.hi(), dest.high);
+}
+
+void
+MacroAssembler::xor64(Imm64 imm, Register64 dest)
+{
+    if (imm.low().value)
+        xor32(imm.low(), dest.low);
+    if (imm.hi().value)
+        xor32(imm.hi(), dest.high);
+}
+
+void
+MacroAssembler::or32(Register src, Register dest)
+{
+    ma_orr(src, dest);
+}
+
+void
+MacroAssembler::or32(Imm32 imm, Register dest)
+{
+    ScratchRegisterScope scratch(*this);
+    ma_orr(imm, dest, scratch);
+}
+
+void
+MacroAssembler::or32(Imm32 imm, const Address& dest)
+{
+    ScratchRegisterScope scratch(*this);
+    SecondScratchRegisterScope scratch2(*this);
+
+    ma_ldr(dest, scratch, scratch2);
+    ma_orr(imm, scratch, scratch2);
+    ma_str(scratch, dest, scratch2);
+}
+
+void
+MacroAssembler::orPtr(Register src, Register dest)
+{
+    ma_orr(src, dest);
+}
+
+void
+MacroAssembler::orPtr(Imm32 imm, Register dest)
+{
+    ScratchRegisterScope scratch(*this);
+    ma_orr(imm, dest, scratch);
+}
+
+void
+MacroAssembler::and64(Register64 src, Register64 dest)
+{
+    and32(src.low, dest.low);
+    and32(src.high, dest.high);
+}
+
+void
+MacroAssembler::or64(Register64 src, Register64 dest)
+{
+    or32(src.low, dest.low);
+    or32(src.high, dest.high);
+}
+
+void
+MacroAssembler::xor64(Register64 src, Register64 dest)
+{
+    ma_eor(src.low, dest.low);
+    ma_eor(src.high, dest.high);
+}
+
+void
+MacroAssembler::xor32(Register src, Register dest)
+{
+    ma_eor(src, dest, SetCC);
+}
+
+void
+MacroAssembler::xor32(Imm32 imm, Register dest)
+{
+    ScratchRegisterScope scratch(*this);
+    ma_eor(imm, dest, scratch, SetCC);
+}
+
+void
+MacroAssembler::xorPtr(Register src, Register dest)
+{
+    ma_eor(src, dest);
+}
+
+void
+MacroAssembler::xorPtr(Imm32 imm, Register dest)
+{
+    ScratchRegisterScope scratch(*this);
+    ma_eor(imm, dest, scratch);
+}
+
+// ===============================================================
+// Arithmetic functions
+
+void
+MacroAssembler::add32(Register src, Register dest)
+{
+    ma_add(src, dest, SetCC);
+}
+
+void
+MacroAssembler::add32(Imm32 imm, Register dest)
+{
+    ScratchRegisterScope scratch(*this);
+    ma_add(imm, dest, scratch, SetCC);
+}
+
+void
+MacroAssembler::add32(Imm32 imm, const Address& dest)
+{
+    ScratchRegisterScope scratch(*this);
+    SecondScratchRegisterScope scratch2(*this);
+
+    ma_ldr(dest, scratch, scratch2);
+    ma_add(imm, scratch, scratch2, SetCC);
+    ma_str(scratch, dest, scratch2);
+}
+
+void
+MacroAssembler::addPtr(Register src, Register dest)
+{
+    ma_add(src, dest);
+}
+
+void
+MacroAssembler::addPtr(Imm32 imm, Register dest)
+{
+    ScratchRegisterScope scratch(*this);
+    ma_add(imm, dest, scratch);
+}
+
+void
+MacroAssembler::addPtr(ImmWord imm, Register dest)
+{
+    addPtr(Imm32(imm.value), dest);
+}
+
+void
+MacroAssembler::addPtr(Imm32 imm, const Address& dest)
+{
+    ScratchRegisterScope scratch(*this);
+    SecondScratchRegisterScope scratch2(*this);
+
+    ma_ldr(dest, scratch, scratch2);
+    ma_add(imm, scratch, scratch2);
+    ma_str(scratch, dest, scratch2);
+}
+
+void
+MacroAssembler::addPtr(const Address& src, Register dest)
+{
+    ScratchRegisterScope scratch(*this);
+    SecondScratchRegisterScope scratch2(*this);
+
+    ma_ldr(src, scratch, scratch2);
+    ma_add(scratch, dest, SetCC);
+}
+
+void
+MacroAssembler::add64(Register64 src, Register64 dest)
+{
+    ma_add(src.low, dest.low, SetCC);
+    ma_adc(src.high, dest.high);
+}
+
+void
+MacroAssembler::add64(Imm32 imm, Register64 dest)
+{
+    ScratchRegisterScope scratch(*this);
+    ma_add(imm, dest.low, scratch, SetCC);
+    as_adc(dest.high, dest.high, Imm8(0), LeaveCC);
+}
+
+void
+MacroAssembler::add64(Imm64 imm, Register64 dest)
+{
+    ScratchRegisterScope scratch(*this);
+    ma_add(imm.low(), dest.low, scratch, SetCC);
+    ma_adc(imm.hi(), dest.high, scratch, LeaveCC);
+}
+
+void
+MacroAssembler::addDouble(FloatRegister src, FloatRegister dest)
+{
+    ma_vadd(dest, src, dest);
+}
+
+void
+MacroAssembler::addFloat32(FloatRegister src, FloatRegister dest)
+{
+    ma_vadd_f32(dest, src, dest);
+}
+
+void
+MacroAssembler::sub32(Register src, Register dest)
+{
+    ma_sub(src, dest, SetCC);
+}
+
+void
+MacroAssembler::sub32(Imm32 imm, Register dest)
+{
+    ScratchRegisterScope scratch(*this);
+    ma_sub(imm, dest, scratch, SetCC);
+}
+
+void
+MacroAssembler::sub32(const Address& src, Register dest)
+{
+    ScratchRegisterScope scratch(*this);
+    SecondScratchRegisterScope scratch2(*this);
+
+    ma_ldr(src, scratch, scratch2);
+    ma_sub(scratch, dest, SetCC);
+}
+
+void
+MacroAssembler::subPtr(Register src, Register dest)
+{
+    ma_sub(src, dest);
+}
+
+void
+MacroAssembler::subPtr(Register src, const Address& dest)
+{
+    ScratchRegisterScope scratch(*this);
+    SecondScratchRegisterScope scratch2(*this);
+
+    ma_ldr(dest, scratch, scratch2);
+    ma_sub(src, scratch);
+    ma_str(scratch, dest, scratch2);
+}
+
+void
+MacroAssembler::subPtr(Imm32 imm, Register dest)
+{
+    ScratchRegisterScope scratch(*this);
+    ma_sub(imm, dest, scratch);
+}
+
+void
+MacroAssembler::subPtr(const Address& addr, Register dest)
+{
+    ScratchRegisterScope scratch(*this);
+    SecondScratchRegisterScope scratch2(*this);
+
+    ma_ldr(addr, scratch, scratch2);
+    ma_sub(scratch, dest);
+}
+
+void
+MacroAssembler::sub64(Register64 src, Register64 dest)
+{
+    ma_sub(src.low, dest.low, SetCC);
+    ma_sbc(src.high, dest.high, LeaveCC);
+}
+
+void
+MacroAssembler::sub64(Imm64 imm, Register64 dest)
+{
+    ScratchRegisterScope scratch(*this);
+    ma_sub(imm.low(), dest.low, scratch, SetCC);
+    ma_sbc(imm.hi(), dest.high, scratch, LeaveCC);
+}
+
+void
+MacroAssembler::subDouble(FloatRegister src, FloatRegister dest)
+{
+    ma_vsub(dest, src, dest);
+}
+
+void
+MacroAssembler::subFloat32(FloatRegister src, FloatRegister dest)
+{
+    ma_vsub_f32(dest, src, dest);
+}
+
+void
+MacroAssembler::mul32(Register rhs, Register srcDest)
+{
+    as_mul(srcDest, srcDest, rhs);
+}
+
+void
+MacroAssembler::mul64(Imm64 imm, const Register64& dest)
+{
+    // LOW32  = LOW(LOW(dest) * LOW(imm));
+    // HIGH32 = LOW(HIGH(dest) * LOW(imm)) [multiply imm into upper bits]
+    //        + LOW(LOW(dest) * HIGH(imm)) [multiply dest into upper bits]
+    //        + HIGH(LOW(dest) * LOW(imm)) [carry]
+
+    ScratchRegisterScope scratch(*this);
+    SecondScratchRegisterScope scratch2(*this);
+
+    // HIGH(dest) = LOW(HIGH(dest) * LOW(imm));
+    ma_mov(Imm32(imm.value & 0xFFFFFFFFL), scratch);
+    as_mul(dest.high, dest.high, scratch);
+
+    // high:low = LOW(dest) * LOW(imm);
+    as_umull(scratch2, scratch, dest.low, scratch);
+
+    // HIGH(dest) += high;
+    as_add(dest.high, dest.high, O2Reg(scratch2));
+
+    // HIGH(dest) += LOW(LOW(dest) * HIGH(imm));
+    if (((imm.value >> 32) & 0xFFFFFFFFL) == 5)
+        as_add(scratch2, dest.low, lsl(dest.low, 2));
+    else
+        MOZ_CRASH("Not supported imm");
+    as_add(dest.high, dest.high, O2Reg(scratch2));
+
+    // LOW(dest) = low;
+    ma_mov(scratch, dest.low);
+}
+
+void
+MacroAssembler::mul64(Imm64 imm, const Register64& dest, const Register temp)
+{
+    // LOW32  = LOW(LOW(dest) * LOW(src));                                  (1)
+    // HIGH32 = LOW(HIGH(dest) * LOW(src)) [multiply src into upper bits]   (2)
+    //        + LOW(LOW(dest) * HIGH(src)) [multiply dest into upper bits]  (3)
+    //        + HIGH(LOW(dest) * LOW(src)) [carry]                          (4)
+
+    MOZ_ASSERT(temp != dest.high && temp != dest.low);
+
+    // Compute mul64
+    ScratchRegisterScope scratch(*this);
+    ma_mul(dest.high, imm.low(), dest.high, scratch); // (2)
+    ma_mul(dest.low, imm.hi(), temp, scratch); // (3)
+    ma_add(dest.high, temp, temp);
+    ma_umull(dest.low, imm.low(), dest.high, dest.low, scratch); // (4) + (1)
+    ma_add(temp, dest.high, dest.high);
+}
+
+void
+MacroAssembler::mul64(const Register64& src, const Register64& dest, const Register temp)
+{
+    // LOW32  = LOW(LOW(dest) * LOW(src));                                  (1)
+    // HIGH32 = LOW(HIGH(dest) * LOW(src)) [multiply src into upper bits]   (2)
+    //        + LOW(LOW(dest) * HIGH(src)) [multiply dest into upper bits]  (3)
+    //        + HIGH(LOW(dest) * LOW(src)) [carry]                          (4)
+
+    MOZ_ASSERT(dest != src);
+    MOZ_ASSERT(dest.low != src.high && dest.high != src.low);
+
+    // Compute mul64
+    ma_mul(dest.high, src.low, dest.high); // (2)
+    ma_mul(src.high, dest.low, temp); // (3)
+    ma_add(dest.high, temp, temp);
+    ma_umull(dest.low, src.low, dest.high, dest.low); // (4) + (1)
+    ma_add(temp, dest.high, dest.high);
+}
+
+void
+MacroAssembler::mulBy3(Register src, Register dest)
+{
+    as_add(dest, src, lsl(src, 1));
+}
+
+void
+MacroAssembler::mulFloat32(FloatRegister src, FloatRegister dest)
+{
+    ma_vmul_f32(dest, src, dest);
+}
+
+void
+MacroAssembler::mulDouble(FloatRegister src, FloatRegister dest)
+{
+    ma_vmul(dest, src, dest);
+}
+
+void
+MacroAssembler::mulDoublePtr(ImmPtr imm, Register temp, FloatRegister dest)
+{
+    ScratchRegisterScope scratch(*this);
+    ScratchDoubleScope scratchDouble(*this);
+
+    movePtr(imm, scratch);
+    ma_vldr(Operand(Address(scratch, 0)).toVFPAddr(), scratchDouble);
+    mulDouble(scratchDouble, dest);
+}
+
+void
+MacroAssembler::quotient32(Register rhs, Register srcDest, bool isUnsigned)
+{
+    MOZ_ASSERT(HasIDIV());
+    if (isUnsigned)
+        ma_udiv(srcDest, rhs, srcDest);
+    else
+        ma_sdiv(srcDest, rhs, srcDest);
+}
+
+void
+MacroAssembler::remainder32(Register rhs, Register srcDest, bool isUnsigned)
+{
+    MOZ_ASSERT(HasIDIV());
+
+    ScratchRegisterScope scratch(*this);
+    if (isUnsigned)
+        ma_umod(srcDest, rhs, srcDest, scratch);
+    else
+        ma_smod(srcDest, rhs, srcDest, scratch);
+}
+
+void
+MacroAssembler::divFloat32(FloatRegister src, FloatRegister dest)
+{
+    ma_vdiv_f32(dest, src, dest);
+}
+
+void
+MacroAssembler::divDouble(FloatRegister src, FloatRegister dest)
+{
+    ma_vdiv(dest, src, dest);
+}
+
+void
+MacroAssembler::inc64(AbsoluteAddress dest)
+{
+    ScratchRegisterScope scratch(*this);
+
+    ma_strd(r0, r1, EDtrAddr(sp, EDtrOffImm(-8)), PreIndex);
+
+    ma_mov(Imm32((int32_t)dest.addr), scratch);
+    ma_ldrd(EDtrAddr(scratch, EDtrOffImm(0)), r0, r1);
+
+    as_add(r0, r0, Imm8(1), SetCC);
+    as_adc(r1, r1, Imm8(0), LeaveCC);
+
+    ma_strd(r0, r1, EDtrAddr(scratch, EDtrOffImm(0)));
+    ma_ldrd(EDtrAddr(sp, EDtrOffImm(8)), r0, r1, PostIndex);
+}
+
+void
+MacroAssembler::neg32(Register reg)
+{
+    ma_neg(reg, reg, SetCC);
+}
+
+void
+MacroAssembler::neg64(Register64 reg)
+{
+    as_rsb(reg.low, reg.low, Imm8(0), SetCC);
+    as_rsc(reg.high, reg.high, Imm8(0));
+}
+
+void
+MacroAssembler::negateDouble(FloatRegister reg)
+{
+    ma_vneg(reg, reg);
+}
+
+void
+MacroAssembler::negateFloat(FloatRegister reg)
+{
+    ma_vneg_f32(reg, reg);
+}
+
+void
+MacroAssembler::absFloat32(FloatRegister src, FloatRegister dest)
+{
+    if (src != dest)
+        ma_vmov_f32(src, dest);
+    ma_vabs_f32(dest, dest);
+}
+
+void
+MacroAssembler::absDouble(FloatRegister src, FloatRegister dest)
+{
+    if (src != dest)
+        ma_vmov(src, dest);
+    ma_vabs(dest, dest);
+}
+
+void
+MacroAssembler::sqrtFloat32(FloatRegister src, FloatRegister dest)
+{
+    ma_vsqrt_f32(src, dest);
+}
+
+void
+MacroAssembler::sqrtDouble(FloatRegister src, FloatRegister dest)
+{
+    ma_vsqrt(src, dest);
+}
+
+void
+MacroAssembler::minFloat32(FloatRegister other, FloatRegister srcDest, bool handleNaN)
+{
+    minMaxFloat32(srcDest, other, handleNaN, false);
+}
+
+void
+MacroAssembler::minDouble(FloatRegister other, FloatRegister srcDest, bool handleNaN)
+{
+    minMaxDouble(srcDest, other, handleNaN, false);
+}
+
+void
+MacroAssembler::maxFloat32(FloatRegister other, FloatRegister srcDest, bool handleNaN)
+{
+    minMaxFloat32(srcDest, other, handleNaN, true);
+}
+
+void
+MacroAssembler::maxDouble(FloatRegister other, FloatRegister srcDest, bool handleNaN)
+{
+    minMaxDouble(srcDest, other, handleNaN, true);
+}
+
+// ===============================================================
+// Shift functions
+
+void
+MacroAssembler::lshiftPtr(Imm32 imm, Register dest)
+{
+    MOZ_ASSERT(0 <= imm.value && imm.value < 32);
+    ma_lsl(imm, dest, dest);
+}
+
+void
+MacroAssembler::lshift64(Imm32 imm, Register64 dest)
+{
+    MOZ_ASSERT(0 <= imm.value && imm.value < 64);
+    if (imm.value == 0) {
+        return;
+    } else if (imm.value < 32) {
+        as_mov(dest.high, lsl(dest.high, imm.value));
+        as_orr(dest.high, dest.high, lsr(dest.low, 32 - imm.value));
+        as_mov(dest.low, lsl(dest.low, imm.value));
+    } else {
+        as_mov(dest.high, lsl(dest.low, imm.value - 32));
+        ma_mov(Imm32(0), dest.low);
+    }
+}
+
+void
+MacroAssembler::lshift64(Register unmaskedShift, Register64 dest)
+{
+    // dest.high = dest.high << shift | dest.low << shift - 32 | dest.low >> 32 - shift
+    // Note: one of the two dest.low shift will always yield zero due to negative shift.
+
+    ScratchRegisterScope shift(*this);
+    as_and(shift, unmaskedShift, Imm8(0x3f));
+    as_mov(dest.high, lsl(dest.high, shift));
+    as_sub(shift, shift, Imm8(32));
+    as_orr(dest.high, dest.high, lsl(dest.low, shift));
+    ma_neg(shift, shift);
+    as_orr(dest.high, dest.high, lsr(dest.low, shift));
+    as_and(shift, unmaskedShift, Imm8(0x3f));
+    as_mov(dest.low, lsl(dest.low, shift));
+}
+
+void
+MacroAssembler::lshift32(Register src, Register dest)
+{
+    ma_lsl(src, dest, dest);
+}
+
+void
+MacroAssembler::lshift32(Imm32 imm, Register dest)
+{
+    MOZ_ASSERT(0 <= imm.value && imm.value < 32);
+    lshiftPtr(imm, dest);
+}
+
+void
+MacroAssembler::rshiftPtr(Imm32 imm, Register dest)
+{
+    MOZ_ASSERT(0 <= imm.value && imm.value < 32);
+    ma_lsr(imm, dest, dest);
+}
+
+void
+MacroAssembler::rshift32(Register src, Register dest)
+{
+    ma_lsr(src, dest, dest);
+}
+
+void
+MacroAssembler::rshift32(Imm32 imm, Register dest)
+{
+    MOZ_ASSERT(0 <= imm.value && imm.value < 32);
+    rshiftPtr(imm, dest);
+}
+
+void
+MacroAssembler::rshiftPtrArithmetic(Imm32 imm, Register dest)
+{
+    MOZ_ASSERT(0 <= imm.value && imm.value < 32);
+    ma_asr(imm, dest, dest);
+}
+
+void
+MacroAssembler::rshift64Arithmetic(Imm32 imm, Register64 dest)
+{
+    MOZ_ASSERT(0 <= imm.value && imm.value < 64);
+
+    if (imm.value < 32) {
+        as_mov(dest.low, lsr(dest.low, imm.value));
+        as_orr(dest.low, dest.low, lsl(dest.high, 32 - imm.value));
+        as_mov(dest.high, asr(dest.high, imm.value));
+    } else if (imm.value == 32) {
+        as_mov(dest.low, O2Reg(dest.high));
+        as_mov(dest.high, asr(dest.high, 31));
+    } else {
+        as_mov(dest.low, asr(dest.high, imm.value - 32));
+        as_mov(dest.high, asr(dest.high, 31));
+    }
+}
+
+void
+MacroAssembler::rshift64Arithmetic(Register unmaskedShift, Register64 dest)
+{
+    Label proceed;
+
+    // dest.low = dest.low >>> shift | dest.high <<< 32 - shift
+    // if (shift - 32 >= 0)
+    //   dest.low |= dest.high >>> shift - 32
+    // Note: Negative shifts yield a zero as result, except for the signed
+    //       right shift. Therefore we need to test for it and only do it if
+    //       it isn't negative.
+    ScratchRegisterScope shift(*this);
+
+    as_and(shift, unmaskedShift, Imm8(0x3f));
+    as_mov(dest.low, lsr(dest.low, shift));
+    as_rsb(shift, shift, Imm8(32));
+    as_orr(dest.low, dest.low, lsl(dest.high, shift));
+    ma_neg(shift, shift, SetCC);
+    ma_b(&proceed, Signed);
+
+    as_orr(dest.low, dest.low, asr(dest.high, shift));
+
+    bind(&proceed);
+    as_and(shift, unmaskedShift, Imm8(0x3f));
+    as_mov(dest.high, asr(dest.high, shift));
+}
+
+void
+MacroAssembler::rshift32Arithmetic(Register src, Register dest)
+{
+    ma_asr(src, dest, dest);
+}
+
+void
+MacroAssembler::rshift32Arithmetic(Imm32 imm, Register dest)
+{
+    MOZ_ASSERT(0 <= imm.value && imm.value < 32);
+    rshiftPtrArithmetic(imm, dest);
+}
+
+void
+MacroAssembler::rshift64(Imm32 imm, Register64 dest)
+{
+    MOZ_ASSERT(0 <= imm.value && imm.value < 64);
+    MOZ_ASSERT(0 <= imm.value && imm.value < 64);
+    if (imm.value < 32) {
+        as_mov(dest.low, lsr(dest.low, imm.value));
+        as_orr(dest.low, dest.low, lsl(dest.high, 32 - imm.value));
+        as_mov(dest.high, lsr(dest.high, imm.value));
+    } else if (imm.value == 32) {
+        ma_mov(dest.high, dest.low);
+        ma_mov(Imm32(0), dest.high);
+    } else {
+        ma_lsr(Imm32(imm.value - 32), dest.high, dest.low);
+        ma_mov(Imm32(0), dest.high);
+    }
+}
+
+void
+MacroAssembler::rshift64(Register unmaskedShift, Register64 dest)
+{
+    // dest.low = dest.low >> shift | dest.high >> shift - 32 | dest.high << 32 - shift
+    // Note: one of the two dest.high shifts will always yield zero due to negative shift.
+
+    ScratchRegisterScope shift(*this);
+    as_and(shift, unmaskedShift, Imm8(0x3f));
+    as_mov(dest.low, lsr(dest.low, shift));
+    as_sub(shift, shift, Imm8(32));
+    as_orr(dest.low, dest.low, lsr(dest.high, shift));
+    ma_neg(shift, shift);
+    as_orr(dest.low, dest.low, lsl(dest.high, shift));
+    as_and(shift, unmaskedShift, Imm8(0x3f));
+    as_mov(dest.high, lsr(dest.high, shift));
+}
+
+// ===============================================================
+// Rotate functions
+void
+MacroAssembler::rotateLeft(Imm32 count, Register input, Register dest)
+{
+    if (count.value)
+        ma_rol(count, input, dest);
+    else
+        ma_mov(input, dest);
+}
+
+void
+MacroAssembler::rotateLeft(Register count, Register input, Register dest)
+{
+    ScratchRegisterScope scratch(*this);
+    ma_rol(count, input, dest, scratch);
+}
+
+void
+MacroAssembler::rotateLeft64(Imm32 count, Register64 input, Register64 dest, Register temp)
+{
+    MOZ_ASSERT(temp == InvalidReg);
+    MOZ_ASSERT(input.low != dest.high && input.high != dest.low);
+
+    int32_t amount = count.value & 0x3f;
+    if (amount > 32) {
+        rotateRight64(Imm32(64 - amount), input, dest, temp);
+    } else {
+        ScratchRegisterScope scratch(*this);
+        if (amount == 0) {
+            ma_mov(input.low, dest.low);
+            ma_mov(input.high, dest.high);
+        } else if (amount == 32) {
+            ma_mov(input.low, scratch);
+            ma_mov(input.high, dest.low);
+            ma_mov(scratch, dest.high);
+        } else {
+            MOZ_ASSERT(0 < amount && amount < 32);
+            ma_mov(dest.high, scratch);
+            as_mov(dest.high, lsl(dest.high, amount));
+            as_orr(dest.high, dest.high, lsr(dest.low, 32 - amount));
+            as_mov(dest.low, lsl(dest.low, amount));
+            as_orr(dest.low, dest.low, lsr(scratch, 32 - amount));
+        }
+    }
+}
+
+void
+MacroAssembler::rotateLeft64(Register shift, Register64 src, Register64 dest, Register temp)
+{
+    MOZ_ASSERT(shift != temp);
+    MOZ_ASSERT(src == dest);
+    MOZ_ASSERT(temp != src.low && temp != src.high);
+    MOZ_ASSERT(shift != src.low && shift != src.high);
+    MOZ_ASSERT(temp != InvalidReg);
+
+    ScratchRegisterScope shift_value(*this);
+    Label high, done;
+
+    ma_mov(src.high, temp);
+    as_and(shift_value, shift, Imm8(0x3f));
+    as_cmp(shift_value, Imm8(32));
+    ma_b(&high, GreaterThanOrEqual);
+
+    // high = high << shift | low >> 32 - shift
+    // low = low << shift | high >> 32 - shift
+    as_mov(dest.high, lsl(src.high, shift_value));
+    as_rsb(shift_value, shift_value, Imm8(32));
+    as_orr(dest.high, dest.high, lsr(src.low, shift_value));
+
+    as_rsb(shift_value, shift_value, Imm8(32));
+    as_mov(dest.low, lsl(src.low, shift_value));
+    as_rsb(shift_value, shift_value, Imm8(32));
+    as_orr(dest.low, dest.low, lsr(temp, shift_value));
+
+    ma_b(&done);
+
+    // A 32 - 64 shift is a 0 - 32 shift in the other direction.
+    bind(&high);
+    as_rsb(shift_value, shift_value, Imm8(64));
+
+    as_mov(dest.high, lsr(src.high, shift_value));
+    as_rsb(shift_value, shift_value, Imm8(32));
+    as_orr(dest.high, dest.high, lsl(src.low, shift_value));
+
+    as_rsb(shift_value, shift_value, Imm8(32));
+    as_mov(dest.low, lsr(src.low, shift_value));
+    as_rsb(shift_value, shift_value, Imm8(32));
+    as_orr(dest.low, dest.low, lsl(temp, shift_value));
+
+    bind(&done);
+}
+
+void
+MacroAssembler::rotateRight(Imm32 count, Register input, Register dest)
+{
+    if (count.value)
+        ma_ror(count, input, dest);
+    else
+        ma_mov(input, dest);
+}
+
+void
+MacroAssembler::rotateRight(Register count, Register input, Register dest)
+{
+    ma_ror(count, input, dest);
+}
+
+void
+MacroAssembler::rotateRight64(Imm32 count, Register64 input, Register64 dest, Register temp)
+{
+    MOZ_ASSERT(temp == InvalidReg);
+    MOZ_ASSERT(input.low != dest.high && input.high != dest.low);
+
+    int32_t amount = count.value & 0x3f;
+    if (amount > 32) {
+        rotateLeft64(Imm32(64 - amount), input, dest, temp);
+    } else {
+        ScratchRegisterScope scratch(*this);
+        if (amount == 0) {
+            ma_mov(input.low, dest.low);
+            ma_mov(input.high, dest.high);
+        } else if (amount == 32) {
+            ma_mov(input.low, scratch);
+            ma_mov(input.high, dest.low);
+            ma_mov(scratch, dest.high);
+        } else {
+            MOZ_ASSERT(0 < amount && amount < 32);
+            ma_mov(dest.high, scratch);
+            as_mov(dest.high, lsr(dest.high, amount));
+            as_orr(dest.high, dest.high, lsl(dest.low, 32 - amount));
+            as_mov(dest.low, lsr(dest.low, amount));
+            as_orr(dest.low, dest.low, lsl(scratch, 32 - amount));
+        }
+    }
+}
+
+void
+MacroAssembler::rotateRight64(Register shift, Register64 src, Register64 dest, Register temp)
+{
+    MOZ_ASSERT(shift != temp);
+    MOZ_ASSERT(src == dest);
+    MOZ_ASSERT(temp != src.low && temp != src.high);
+    MOZ_ASSERT(shift != src.low && shift != src.high);
+    MOZ_ASSERT(temp != InvalidReg);
+
+    ScratchRegisterScope shift_value(*this);
+    Label high, done;
+
+    ma_mov(src.high, temp);
+    as_and(shift_value, shift, Imm8(0x3f));
+    as_cmp(shift_value, Imm8(32));
+    ma_b(&high, GreaterThanOrEqual);
+
+    // high = high >> shift | low << 32 - shift
+    // low = low >> shift | high << 32 - shift
+    as_mov(dest.high, lsr(src.high, shift_value));
+    as_rsb(shift_value, shift_value, Imm8(32));
+    as_orr(dest.high, dest.high, lsl(src.low, shift_value));
+
+    as_rsb(shift_value, shift_value, Imm8(32));
+    as_mov(dest.low, lsr(src.low, shift_value));
+    as_rsb(shift_value, shift_value, Imm8(32));
+    as_orr(dest.low, dest.low, lsl(temp, shift_value));
+
+    ma_b(&done);
+
+    // A 32 - 64 shift is a 0 - 32 shift in the other direction.
+    bind(&high);
+    as_rsb(shift_value, shift_value, Imm8(64));
+
+    as_mov(dest.high, lsl(src.high, shift_value));
+    as_rsb(shift_value, shift_value, Imm8(32));
+    as_orr(dest.high, dest.high, lsr(src.low, shift_value));
+
+    as_rsb(shift_value, shift_value, Imm8(32));
+    as_mov(dest.low, lsl(src.low, shift_value));
+    as_rsb(shift_value, shift_value, Imm8(32));
+    as_orr(dest.low, dest.low, lsr(temp, shift_value));
+
+    bind(&done);
+}
+
+// ===============================================================
+// Condition functions
+
+template <typename T1, typename T2>
+void
+MacroAssembler::cmp32Set(Condition cond, T1 lhs, T2 rhs, Register dest)
+{
+    cmp32(lhs, rhs);
+    emitSet(cond, dest);
+}
+
+template <typename T1, typename T2>
+void
+MacroAssembler::cmpPtrSet(Condition cond, T1 lhs, T2 rhs, Register dest)
+{
+    cmpPtr(lhs, rhs);
+    emitSet(cond, dest);
+}
+
+// ===============================================================
+// Bit counting functions
+
+void
+MacroAssembler::clz32(Register src, Register dest, bool knownNotZero)
+{
+    ma_clz(src, dest);
+}
+
+void
+MacroAssembler::clz64(Register64 src, Register dest)
+{
+    ScratchRegisterScope scratch(*this);
+
+    ma_clz(src.high, scratch);
+    as_cmp(scratch, Imm8(32));
+    ma_mov(scratch, dest, LeaveCC, NotEqual);
+    ma_clz(src.low, dest, Equal);
+    as_add(dest, dest, Imm8(32), LeaveCC, Equal);
+}
+
+void
+MacroAssembler::ctz32(Register src, Register dest, bool knownNotZero)
+{
+    ScratchRegisterScope scratch(*this);
+    ma_ctz(src, dest, scratch);
+}
+
+void
+MacroAssembler::ctz64(Register64 src, Register dest)
+{
+    Label done, high;
+    as_cmp(src.low, Imm8(0));
+    ma_b(&high, Equal);
+
+    ctz32(src.low, dest, /* knownNotZero = */ true);
+    ma_b(&done);
+
+    bind(&high);
+    ctz32(src.high, dest, /* knownNotZero = */ false);
+    as_add(dest, dest, Imm8(32));
+
+    bind(&done);
+}
+
+void
+MacroAssembler::popcnt32(Register input,  Register output, Register tmp)
+{
+    // Equivalent to GCC output of mozilla::CountPopulation32()
+
+    ScratchRegisterScope scratch(*this);
+
+    if (input != output)
+        ma_mov(input, output);
+    as_mov(tmp, asr(output, 1));
+    ma_and(Imm32(0x55555555), tmp, scratch);
+    ma_sub(output, tmp, output);
+    as_mov(tmp, asr(output, 2));
+    ma_mov(Imm32(0x33333333), scratch);
+    ma_and(scratch, output);
+    ma_and(scratch, tmp);
+    ma_add(output, tmp, output);
+    as_add(output, output, lsr(output, 4));
+    ma_and(Imm32(0xF0F0F0F), output, scratch);
+    as_add(output, output, lsl(output, 8));
+    as_add(output, output, lsl(output, 16));
+    as_mov(output, asr(output, 24));
+}
+
+void
+MacroAssembler::popcnt64(Register64 src, Register64 dest, Register tmp)
+{
+    MOZ_ASSERT(dest.low != tmp);
+    MOZ_ASSERT(dest.high != tmp);
+    MOZ_ASSERT(dest.low != dest.high);
+    // The source and destination can overlap. Therefore make sure we don't
+    // clobber the source before we have the data.
+    if (dest.low != src.high) {
+        popcnt32(src.low, dest.low, tmp);
+        popcnt32(src.high, dest.high, tmp);
+    } else {
+        MOZ_ASSERT(dest.high != src.high);
+        popcnt32(src.low, dest.high, tmp);
+        popcnt32(src.high, dest.low, tmp);
+    }
+    ma_add(dest.high, dest.low);
+    ma_mov(Imm32(0), dest.high);
+}
+
+// ===============================================================
+// Branch functions
+
+template <class L>
+void
+MacroAssembler::branch32(Condition cond, Register lhs, Register rhs, L label)
+{
+    ma_cmp(lhs, rhs);
+    ma_b(label, cond);
+}
+
+template <class L>
+void
+MacroAssembler::branch32(Condition cond, Register lhs, Imm32 rhs, L label)
+{
+    ScratchRegisterScope scratch(*this);
+
+    ma_cmp(lhs, rhs, scratch);
+    ma_b(label, cond);
+}
+
+void
+MacroAssembler::branch32(Condition cond, const Address& lhs, Register rhs, Label* label)
+{
+    ScratchRegisterScope scratch(*this);
+    SecondScratchRegisterScope scratch2(*this);
+
+    ma_ldr(lhs, scratch, scratch2);
+    ma_cmp(scratch, rhs);
+    ma_b(label, cond);
+}
+
+void
+MacroAssembler::branch32(Condition cond, const Address& lhs, Imm32 rhs, Label* label)
+{
+    ScratchRegisterScope scratch(*this);
+    SecondScratchRegisterScope scratch2(*this);
+
+    ma_ldr(lhs, scratch, scratch2);
+    ma_cmp(scratch, rhs, scratch2);
+    ma_b(label, cond);
+}
+
+void
+MacroAssembler::branch32(Condition cond, const AbsoluteAddress& lhs, Register rhs, Label* label)
+{
+    ScratchRegisterScope scratch(*this);
+
+    // Load into scratch.
+    movePtr(ImmWord(uintptr_t(lhs.addr)), scratch);
+    ma_ldr(DTRAddr(scratch, DtrOffImm(0)), scratch);
+
+    ma_cmp(scratch, rhs);
+    ma_b(label, cond);
+}
+
+void
+MacroAssembler::branch32(Condition cond, const AbsoluteAddress& lhs, Imm32 rhs, Label* label)
+{
+    ScratchRegisterScope scratch(*this);
+    SecondScratchRegisterScope scratch2(*this);
+
+    // Load into scratch.
+    movePtr(ImmWord(uintptr_t(lhs.addr)), scratch);
+    ma_ldr(DTRAddr(scratch, DtrOffImm(0)), scratch);
+
+    ma_cmp(scratch, rhs, scratch2);
+    ma_b(label, cond);
+}
+
+void
+MacroAssembler::branch32(Condition cond, const BaseIndex& lhs, Imm32 rhs, Label* label)
+{
+    SecondScratchRegisterScope scratch2(*this);
+    {
+        ScratchRegisterScope scratch(*this);
+
+        Register base = lhs.base;
+        uint32_t scale = Imm32::ShiftOf(lhs.scale).value;
+
+        // Load lhs into scratch2.
+        if (lhs.offset != 0) {
+            ma_add(base, Imm32(lhs.offset), scratch, scratch2);
+            ma_ldr(DTRAddr(scratch, DtrRegImmShift(lhs.index, LSL, scale)), scratch2);
+        } else {
+            ma_ldr(DTRAddr(base, DtrRegImmShift(lhs.index, LSL, scale)), scratch2);
+        }
+    }
+    branch32(cond, scratch2, rhs, label);
+}
+
+void
+MacroAssembler::branch32(Condition cond, wasm::SymbolicAddress lhs, Imm32 rhs, Label* label)
+{
+    ScratchRegisterScope scratch(*this);
+    SecondScratchRegisterScope scratch2(*this);
+
+    movePtr(lhs, scratch);
+    ma_ldr(DTRAddr(scratch, DtrOffImm(0)), scratch);
+
+    ma_cmp(scratch, rhs, scratch2);
+    ma_b(label, cond);
+}
+
+void
+MacroAssembler::branch64(Condition cond, const Address& lhs, Imm64 val, Label* label)
+{
+    MOZ_ASSERT(cond == Assembler::NotEqual,
+               "other condition codes not supported");
+
+    branch32(cond, lhs, val.firstHalf(), label);
+    branch32(cond, Address(lhs.base, lhs.offset + sizeof(uint32_t)), val.secondHalf(), label);
+}
+
+void
+MacroAssembler::branch64(Condition cond, const Address& lhs, const Address& rhs, Register scratch,
+                         Label* label)
+{
+    MOZ_ASSERT(cond == Assembler::NotEqual,
+               "other condition codes not supported");
+    MOZ_ASSERT(lhs.base != scratch);
+    MOZ_ASSERT(rhs.base != scratch);
+
+    load32(rhs, scratch);
+    branch32(cond, lhs, scratch, label);
+
+    load32(Address(rhs.base, rhs.offset + sizeof(uint32_t)), scratch);
+    branch32(cond, Address(lhs.base, lhs.offset + sizeof(uint32_t)), scratch, label);
+}
+
+void
+MacroAssembler::branch64(Condition cond, Register64 lhs, Imm64 val, Label* success, Label* fail)
+{
+    bool fallthrough = false;
+    Label fallthroughLabel;
+
+    if (!fail) {
+        fail = &fallthroughLabel;
+        fallthrough = true;
+    }
+
+    switch(cond) {
+      case Assembler::Equal:
+        branch32(Assembler::NotEqual, lhs.low, val.low(), fail);
+        branch32(Assembler::Equal, lhs.high, val.hi(), success);
+        if (!fallthrough)
+            jump(fail);
+        break;
+      case Assembler::NotEqual:
+        branch32(Assembler::NotEqual, lhs.low, val.low(), success);
+        branch32(Assembler::NotEqual, lhs.high, val.hi(), success);
+        if (!fallthrough)
+            jump(fail);
+        break;
+      case Assembler::LessThan:
+      case Assembler::LessThanOrEqual:
+      case Assembler::GreaterThan:
+      case Assembler::GreaterThanOrEqual:
+      case Assembler::Below:
+      case Assembler::BelowOrEqual:
+      case Assembler::Above:
+      case Assembler::AboveOrEqual: {
+        Assembler::Condition cond1 = Assembler::ConditionWithoutEqual(cond);
+        Assembler::Condition cond2 =
+            Assembler::ConditionWithoutEqual(Assembler::InvertCondition(cond));
+        Assembler::Condition cond3 = Assembler::UnsignedCondition(cond);
+
+        cmp32(lhs.high, val.hi());
+        ma_b(success, cond1);
+        ma_b(fail, cond2);
+        cmp32(lhs.low, val.low());
+        ma_b(success, cond3);
+        if (!fallthrough)
+            jump(fail);
+        break;
+      }
+      default:
+        MOZ_CRASH("Condition code not supported");
+        break;
+    }
+
+    if (fallthrough)
+        bind(fail);
+}
+
+void
+MacroAssembler::branch64(Condition cond, Register64 lhs, Register64 rhs, Label* success, Label* fail)
+{
+    bool fallthrough = false;
+    Label fallthroughLabel;
+
+    if (!fail) {
+        fail = &fallthroughLabel;
+        fallthrough = true;
+    }
+
+    switch(cond) {
+      case Assembler::Equal:
+        branch32(Assembler::NotEqual, lhs.low, rhs.low, fail);
+        branch32(Assembler::Equal, lhs.high, rhs.high, success);
+        if (!fallthrough)
+            jump(fail);
+        break;
+      case Assembler::NotEqual:
+        branch32(Assembler::NotEqual, lhs.low, rhs.low, success);
+        branch32(Assembler::NotEqual, lhs.high, rhs.high, success);
+        if (!fallthrough)
+            jump(fail);
+        break;
+      case Assembler::LessThan:
+      case Assembler::LessThanOrEqual:
+      case Assembler::GreaterThan:
+      case Assembler::GreaterThanOrEqual:
+      case Assembler::Below:
+      case Assembler::BelowOrEqual:
+      case Assembler::Above:
+      case Assembler::AboveOrEqual: {
+        Assembler::Condition cond1 = Assembler::ConditionWithoutEqual(cond);
+        Assembler::Condition cond2 =
+            Assembler::ConditionWithoutEqual(Assembler::InvertCondition(cond));
+        Assembler::Condition cond3 = Assembler::UnsignedCondition(cond);
+
+        cmp32(lhs.high, rhs.high);
+        ma_b(success, cond1);
+        ma_b(fail, cond2);
+        cmp32(lhs.low, rhs.low);
+        ma_b(success, cond3);
+        if (!fallthrough)
+            jump(fail);
+        break;
+      }
+      default:
+        MOZ_CRASH("Condition code not supported");
+        break;
+    }
+
+    if (fallthrough)
+        bind(fail);
+}
+
+template <class L>
+void
+MacroAssembler::branchPtr(Condition cond, Register lhs, Register rhs, L label)
+{
+    branch32(cond, lhs, rhs, label);
+}
+
+void
+MacroAssembler::branchPtr(Condition cond, Register lhs, Imm32 rhs, Label* label)
+{
+    branch32(cond, lhs, rhs, label);
+}
+
+void
+MacroAssembler::branchPtr(Condition cond, Register lhs, ImmPtr rhs, Label* label)
+{
+    branchPtr(cond, lhs, ImmWord(uintptr_t(rhs.value)), label);
+}
+
+void
+MacroAssembler::branchPtr(Condition cond, Register lhs, ImmGCPtr rhs, Label* label)
+{
+    ScratchRegisterScope scratch(*this);
+    movePtr(rhs, scratch);
+    branchPtr(cond, lhs, scratch, label);
+}
+
+void
+MacroAssembler::branchPtr(Condition cond, Register lhs, ImmWord rhs, Label* label)
+{
+    branch32(cond, lhs, Imm32(rhs.value), label);
+}
+
+template <class L>
+void
+MacroAssembler::branchPtr(Condition cond, const Address& lhs, Register rhs, L label)
+{
+    branch32(cond, lhs, rhs, label);
+}
+
+void
+MacroAssembler::branchPtr(Condition cond, const Address& lhs, ImmPtr rhs, Label* label)
+{
+    branchPtr(cond, lhs, ImmWord(uintptr_t(rhs.value)), label);
+}
+
+void
+MacroAssembler::branchPtr(Condition cond, const Address& lhs, ImmGCPtr rhs, Label* label)
+{
+    SecondScratchRegisterScope scratch2(*this);
+    loadPtr(lhs, scratch2);
+    branchPtr(cond, scratch2, rhs, label);
+}
+
+void
+MacroAssembler::branchPtr(Condition cond, const Address& lhs, ImmWord rhs, Label* label)
+{
+    SecondScratchRegisterScope scratch2(*this);
+    loadPtr(lhs, scratch2);
+    branchPtr(cond, scratch2, rhs, label);
+}
+
+void
+MacroAssembler::branchPtr(Condition cond, const AbsoluteAddress& lhs, Register rhs, Label* label)
+{
+    SecondScratchRegisterScope scratch2(*this);
+    loadPtr(lhs, scratch2);
+    branchPtr(cond, scratch2, rhs, label);
+}
+
+void
+MacroAssembler::branchPtr(Condition cond, const AbsoluteAddress& lhs, ImmWord rhs, Label* label)
+{
+    SecondScratchRegisterScope scratch2(*this);
+    loadPtr(lhs, scratch2);
+    branchPtr(cond, scratch2, rhs, label);
+}
+
+void
+MacroAssembler::branchPtr(Condition cond, wasm::SymbolicAddress lhs, Register rhs, Label* label)
+{
+    SecondScratchRegisterScope scratch2(*this);
+    loadPtr(lhs, scratch2);
+    branchPtr(cond, scratch2, rhs, label);
+}
+
+template <typename T>
+inline CodeOffsetJump
+MacroAssembler::branchPtrWithPatch(Condition cond, Register lhs, T rhs, RepatchLabel* label)
+{
+    cmpPtr(lhs, rhs);
+    return jumpWithPatch(label, cond);
+}
+
+template <typename T>
+inline CodeOffsetJump
+MacroAssembler::branchPtrWithPatch(Condition cond, Address lhs, T rhs, RepatchLabel* label)
+{
+    SecondScratchRegisterScope scratch2(*this);
+    {
+        ScratchRegisterScope scratch(*this);
+        ma_ldr(lhs, scratch2, scratch);
+    }
+    cmpPtr(scratch2, rhs);
+    return jumpWithPatch(label, cond);
+}
+
+void
+MacroAssembler::branchPrivatePtr(Condition cond, const Address& lhs, Register rhs, Label* label)
+{
+    branchPtr(cond, lhs, rhs, label);
+}
+
+void
+MacroAssembler::branchFloat(DoubleCondition cond, FloatRegister lhs, FloatRegister rhs,
+                            Label* label)
+{
+    compareFloat(lhs, rhs);
+
+    if (cond == DoubleNotEqual) {
+        // Force the unordered cases not to jump.
+        Label unordered;
+        ma_b(&unordered, VFP_Unordered);
+        ma_b(label, VFP_NotEqualOrUnordered);
+        bind(&unordered);
+        return;
+    }
+
+    if (cond == DoubleEqualOrUnordered) {
+        ma_b(label, VFP_Unordered);
+        ma_b(label, VFP_Equal);
+        return;
+    }
+
+    ma_b(label, ConditionFromDoubleCondition(cond));
+}
+
+void
+MacroAssembler::branchTruncateFloat32MaybeModUint32(FloatRegister src, Register dest, Label* fail)
+{
+    branchTruncateFloat32ToInt32(src, dest, fail);
+}
+
+void
+MacroAssembler::branchTruncateFloat32ToInt32(FloatRegister src, Register dest, Label* fail)
+{
+    ScratchFloat32Scope scratchFloat32(*this);
+    ScratchRegisterScope scratch(*this);
+
+    ma_vcvt_F32_I32(src, scratchFloat32.sintOverlay());
+    ma_vxfer(scratchFloat32, dest);
+    ma_cmp(dest, Imm32(0x7fffffff), scratch);
+    ma_cmp(dest, Imm32(0x80000000), scratch, Assembler::NotEqual);
+    ma_b(fail, Assembler::Equal);
+}
+
+void
+MacroAssembler::branchDouble(DoubleCondition cond, FloatRegister lhs, FloatRegister rhs,
+                             Label* label)
+{
+    compareDouble(lhs, rhs);
+
+    if (cond == DoubleNotEqual) {
+        // Force the unordered cases not to jump.
+        Label unordered;
+        ma_b(&unordered, VFP_Unordered);
+        ma_b(label, VFP_NotEqualOrUnordered);
+        bind(&unordered);
+        return;
+    }
+
+    if (cond == DoubleEqualOrUnordered) {
+        ma_b(label, VFP_Unordered);
+        ma_b(label, VFP_Equal);
+        return;
+    }
+
+    ma_b(label, ConditionFromDoubleCondition(cond));
+}
+
+void
+MacroAssembler::branchTruncateDoubleMaybeModUint32(FloatRegister src, Register dest, Label* fail)
+{
+    branchTruncateDoubleToInt32(src, dest, fail);
+}
+
+// There are two options for implementing branchTruncateDoubleToInt32:
+//
+// 1. Convert the floating point value to an integer, if it did not fit, then it
+// was clamped to INT_MIN/INT_MAX, and we can test it. NOTE: if the value
+// really was supposed to be INT_MAX / INT_MIN then it will be wrong.
+//
+// 2. Convert the floating point value to an integer, if it did not fit, then it
+// set one or two bits in the fpcsr. Check those.
+void
+MacroAssembler::branchTruncateDoubleToInt32(FloatRegister src, Register dest, Label* fail)
+{
+    ScratchDoubleScope scratchDouble(*this);
+    FloatRegister scratchSIntReg = scratchDouble.sintOverlay();
+    ScratchRegisterScope scratch(*this);
+
+    ma_vcvt_F64_I32(src, scratchSIntReg);
+    ma_vxfer(scratchSIntReg, dest);
+    ma_cmp(dest, Imm32(0x7fffffff), scratch);
+    ma_cmp(dest, Imm32(0x80000000), scratch, Assembler::NotEqual);
+    ma_b(fail, Assembler::Equal);
+}
+
+template <typename T, typename L>
+void
+MacroAssembler::branchAdd32(Condition cond, T src, Register dest, L label)
+{
+    add32(src, dest);
+    as_b(label, cond);
+}
+
+template <typename T>
+void
+MacroAssembler::branchSub32(Condition cond, T src, Register dest, Label* label)
+{
+    sub32(src, dest);
+    j(cond, label);
+}
+
+void
+MacroAssembler::decBranchPtr(Condition cond, Register lhs, Imm32 rhs, Label* label)
+{
+    ScratchRegisterScope scratch(*this);
+    ma_sub(rhs, lhs, scratch, SetCC);
+    as_b(label, cond);
+}
+
+template <class L>
+void
+MacroAssembler::branchTest32(Condition cond, Register lhs, Register rhs, L label)
+{
+    MOZ_ASSERT(cond == Zero || cond == NonZero || cond == Signed || cond == NotSigned);
+    // x86 likes test foo, foo rather than cmp foo, #0.
+    // Convert the former into the latter.
+    if (lhs == rhs && (cond == Zero || cond == NonZero))
+        as_cmp(lhs, Imm8(0));
+    else
+        ma_tst(lhs, rhs);
+    ma_b(label, cond);
+}
+
+template <class L>
+void
+MacroAssembler::branchTest32(Condition cond, Register lhs, Imm32 rhs, L label)
+{
+    MOZ_ASSERT(cond == Zero || cond == NonZero || cond == Signed || cond == NotSigned);
+    ScratchRegisterScope scratch(*this);
+    ma_tst(lhs, rhs, scratch);
+    ma_b(label, cond);
+}
+
+void
+MacroAssembler::branchTest32(Condition cond, const Address& lhs, Imm32 rhs, Label* label)
+{
+    SecondScratchRegisterScope scratch2(*this);
+    load32(lhs, scratch2);
+    branchTest32(cond, scratch2, rhs, label);
+}
+
+void
+MacroAssembler::branchTest32(Condition cond, const AbsoluteAddress& lhs, Imm32 rhs, Label* label)
+{
+    SecondScratchRegisterScope scratch2(*this);
+    load32(lhs, scratch2);
+    branchTest32(cond, scratch2, rhs, label);
+}
+
+template <class L>
+void
+MacroAssembler::branchTestPtr(Condition cond, Register lhs, Register rhs, L label)
+{
+    branchTest32(cond, lhs, rhs, label);
+}
+
+void
+MacroAssembler::branchTestPtr(Condition cond, Register lhs, Imm32 rhs, Label* label)
+{
+    branchTest32(cond, lhs, rhs, label);
+}
+
+void
+MacroAssembler::branchTestPtr(Condition cond, const Address& lhs, Imm32 rhs, Label* label)
+{
+    branchTest32(cond, lhs, rhs, label);
+}
+
+template <class L>
+void
+MacroAssembler::branchTest64(Condition cond, Register64 lhs, Register64 rhs, Register temp,
+                             L label)
+{
+    ScratchRegisterScope scratch(*this);
+
+    if (cond == Assembler::Zero) {
+        MOZ_ASSERT(lhs.low == rhs.low);
+        MOZ_ASSERT(lhs.high == rhs.high);
+        ma_orr(lhs.low, lhs.high, scratch);
+        branchTestPtr(cond, scratch, scratch, label);
+    } else {
+        MOZ_CRASH("Unsupported condition");
+    }
+}
+
+void
+MacroAssembler::branchTestUndefined(Condition cond, Register tag, Label* label)
+{
+    branchTestUndefinedImpl(cond, tag, label);
+}
+
+void
+MacroAssembler::branchTestUndefined(Condition cond, const Address& address, Label* label)
+{
+    branchTestUndefinedImpl(cond, address, label);
+}
+
+void
+MacroAssembler::branchTestUndefined(Condition cond, const BaseIndex& address, Label* label)
+{
+    branchTestUndefinedImpl(cond, address, label);
+}
+
+void
+MacroAssembler::branchTestUndefined(Condition cond, const ValueOperand& value, Label* label)
+{
+    branchTestUndefinedImpl(cond, value, label);
+}
+
+template <typename T>
+void
+MacroAssembler::branchTestUndefinedImpl(Condition cond, const T& t, Label* label)
+{
+    Condition c = testUndefined(cond, t);
+    ma_b(label, c);
+}
+
+void
+MacroAssembler::branchTestInt32(Condition cond, Register tag, Label* label)
+{
+    branchTestInt32Impl(cond, tag, label);
+}
+
+void
+MacroAssembler::branchTestInt32(Condition cond, const Address& address, Label* label)
+{
+    branchTestInt32Impl(cond, address, label);
+}
+
+void
+MacroAssembler::branchTestInt32(Condition cond, const BaseIndex& address, Label* label)
+{
+    branchTestInt32Impl(cond, address, label);
+}
+
+void
+MacroAssembler::branchTestInt32(Condition cond, const ValueOperand& value, Label* label)
+{
+    branchTestInt32Impl(cond, value, label);
+}
+
+template <typename T>
+void
+MacroAssembler::branchTestInt32Impl(Condition cond, const T& t, Label* label)
+{
+    Condition c = testInt32(cond, t);
+    ma_b(label, c);
+}
+
+void
+MacroAssembler::branchTestInt32Truthy(bool truthy, const ValueOperand& value, Label* label)
+{
+    Condition c = testInt32Truthy(truthy, value);
+    ma_b(label, c);
+}
+
+void
+MacroAssembler::branchTestDouble(Condition cond, Register tag, Label* label)
+{
+    branchTestDoubleImpl(cond, tag, label);
+}
+
+void
+MacroAssembler::branchTestDouble(Condition cond, const Address& address, Label* label)
+{
+    branchTestDoubleImpl(cond, address, label);
+}
+
+void
+MacroAssembler::branchTestDouble(Condition cond, const BaseIndex& address, Label* label)
+{
+    branchTestDoubleImpl(cond, address, label);
+}
+
+void
+MacroAssembler::branchTestDouble(Condition cond, const ValueOperand& value, Label* label)
+{
+    branchTestDoubleImpl(cond, value, label);
+}
+
+template <typename T>
+void
+MacroAssembler::branchTestDoubleImpl(Condition cond, const T& t, Label* label)
+{
+    Condition c = testDouble(cond, t);
+    ma_b(label, c);
+}
+
+void
+MacroAssembler::branchTestDoubleTruthy(bool truthy, FloatRegister reg, Label* label)
+{
+    Condition c = testDoubleTruthy(truthy, reg);
+    ma_b(label, c);
+}
+
+void
+MacroAssembler::branchTestNumber(Condition cond, Register tag, Label* label)
+{
+    branchTestNumberImpl(cond, tag, label);
+}
+
+void
+MacroAssembler::branchTestNumber(Condition cond, const ValueOperand& value, Label* label)
+{
+    branchTestNumberImpl(cond, value, label);
+}
+
+template <typename T>
+void
+MacroAssembler::branchTestNumberImpl(Condition cond, const T& t, Label* label)
+{
+    cond = testNumber(cond, t);
+    ma_b(label, cond);
+}
+
+void
+MacroAssembler::branchTestBoolean(Condition cond, Register tag, Label* label)
+{
+    branchTestBooleanImpl(cond, tag, label);
+}
+
+void
+MacroAssembler::branchTestBoolean(Condition cond, const Address& address, Label* label)
+{
+    branchTestBooleanImpl(cond, address, label);
+}
+
+void
+MacroAssembler::branchTestBoolean(Condition cond, const BaseIndex& address, Label* label)
+{
+    branchTestBooleanImpl(cond, address, label);
+}
+
+void
+MacroAssembler::branchTestBoolean(Condition cond, const ValueOperand& value, Label* label)
+{
+    branchTestBooleanImpl(cond, value, label);
+}
+
+template <typename T>
+void
+MacroAssembler::branchTestBooleanImpl(Condition cond, const T& t, Label* label)
+{
+    Condition c = testBoolean(cond, t);
+    ma_b(label, c);
+}
+
+void
+MacroAssembler::branchTestBooleanTruthy(bool truthy, const ValueOperand& value, Label* label)
+{
+    Condition c = testBooleanTruthy(truthy, value);
+    ma_b(label, c);
+}
+
+void
+MacroAssembler::branchTestString(Condition cond, Register tag, Label* label)
+{
+    branchTestStringImpl(cond, tag, label);
+}
+
+void
+MacroAssembler::branchTestString(Condition cond, const BaseIndex& address, Label* label)
+{
+    branchTestStringImpl(cond, address, label);
+}
+
+void
+MacroAssembler::branchTestString(Condition cond, const ValueOperand& value, Label* label)
+{
+    branchTestStringImpl(cond, value, label);
+}
+
+template <typename T>
+void
+MacroAssembler::branchTestStringImpl(Condition cond, const T& t, Label* label)
+{
+    Condition c = testString(cond, t);
+    ma_b(label, c);
+}
+
+void
+MacroAssembler::branchTestStringTruthy(bool truthy, const ValueOperand& value, Label* label)
+{
+    Condition c = testStringTruthy(truthy, value);
+    ma_b(label, c);
+}
+
+void
+MacroAssembler::branchTestSymbol(Condition cond, Register tag, Label* label)
+{
+    branchTestSymbolImpl(cond, tag, label);
+}
+
+void
+MacroAssembler::branchTestSymbol(Condition cond, const BaseIndex& address, Label* label)
+{
+    branchTestSymbolImpl(cond, address, label);
+}
+
+void
+MacroAssembler::branchTestSymbol(Condition cond, const ValueOperand& value, Label* label)
+{
+    branchTestSymbolImpl(cond, value, label);
+}
+
+template <typename T>
+void
+MacroAssembler::branchTestSymbolImpl(Condition cond, const T& t, Label* label)
+{
+    Condition c = testSymbol(cond, t);
+    ma_b(label, c);
+}
+
+void
+MacroAssembler::branchTestNull(Condition cond, Register tag, Label* label)
+{
+    branchTestNullImpl(cond, tag, label);
+}
+
+void
+MacroAssembler::branchTestNull(Condition cond, const Address& address, Label* label)
+{
+    branchTestNullImpl(cond, address, label);
+}
+
+void
+MacroAssembler::branchTestNull(Condition cond, const BaseIndex& address, Label* label)
+{
+    branchTestNullImpl(cond, address, label);
+}
+
+void
+MacroAssembler::branchTestNull(Condition cond, const ValueOperand& value, Label* label)
+{
+    branchTestNullImpl(cond, value, label);
+}
+
+template <typename T>
+void
+MacroAssembler::branchTestNullImpl(Condition cond, const T& t, Label* label)
+{
+    Condition c = testNull(cond, t);
+    ma_b(label, c);
+}
+
+void
+MacroAssembler::branchTestObject(Condition cond, Register tag, Label* label)
+{
+    branchTestObjectImpl(cond, tag, label);
+}
+
+void
+MacroAssembler::branchTestObject(Condition cond, const Address& address, Label* label)
+{
+    branchTestObjectImpl(cond, address, label);
+}
+
+void
+MacroAssembler::branchTestObject(Condition cond, const BaseIndex& address, Label* label)
+{
+    branchTestObjectImpl(cond, address, label);
+}
+
+void
+MacroAssembler::branchTestObject(Condition cond, const ValueOperand& value, Label* label)
+{
+    branchTestObjectImpl(cond, value, label);
+}
+
+template <typename T>
+void
+MacroAssembler::branchTestObjectImpl(Condition cond, const T& t, Label* label)
+{
+    Condition c = testObject(cond, t);
+    ma_b(label, c);
+}
+
+void
+MacroAssembler::branchTestGCThing(Condition cond, const Address& address, Label* label)
+{
+    branchTestGCThingImpl(cond, address, label);
+}
+
+void
+MacroAssembler::branchTestGCThing(Condition cond, const BaseIndex& address, Label* label)
+{
+    branchTestGCThingImpl(cond, address, label);
+}
+
+template <typename T>
+void
+MacroAssembler::branchTestGCThingImpl(Condition cond, const T& t, Label* label)
+{
+    Condition c = testGCThing(cond, t);
+    ma_b(label, c);
+}
+
+void
+MacroAssembler::branchTestPrimitive(Condition cond, Register tag, Label* label)
+{
+    branchTestPrimitiveImpl(cond, tag, label);
+}
+
+void
+MacroAssembler::branchTestPrimitive(Condition cond, const ValueOperand& value, Label* label)
+{
+    branchTestPrimitiveImpl(cond, value, label);
+}
+
+template <typename T>
+void
+MacroAssembler::branchTestPrimitiveImpl(Condition cond, const T& t, Label* label)
+{
+    Condition c = testPrimitive(cond, t);
+    ma_b(label, c);
+}
+
+void
+MacroAssembler::branchTestMagic(Condition cond, Register tag, Label* label)
+{
+    branchTestMagicImpl(cond, tag, label);
+}
+
+void
+MacroAssembler::branchTestMagic(Condition cond, const Address& address, Label* label)
+{
+    branchTestMagicImpl(cond, address, label);
+}
+
+void
+MacroAssembler::branchTestMagic(Condition cond, const BaseIndex& address, Label* label)
+{
+    branchTestMagicImpl(cond, address, label);
+}
+
+template <class L>
+void
+MacroAssembler::branchTestMagic(Condition cond, const ValueOperand& value, L label)
+{
+    branchTestMagicImpl(cond, value, label);
+}
+
+template <typename T, class L>
+void
+MacroAssembler::branchTestMagicImpl(Condition cond, const T& t, L label)
+{
+    cond = testMagic(cond, t);
+    ma_b(label, cond);
+}
+
+void
+MacroAssembler::branchTestMagic(Condition cond, const Address& valaddr, JSWhyMagic why, Label* label)
+{
+    branchTestMagic(cond, valaddr, label);
+    branch32(cond, ToPayload(valaddr), Imm32(why), label);
+}
+
+// ========================================================================
+// Memory access primitives.
+void
+MacroAssembler::storeUncanonicalizedDouble(FloatRegister src, const Address& addr)
+{
+    ScratchRegisterScope scratch(*this);
+    ma_vstr(src, addr, scratch);
+}
+void
+MacroAssembler::storeUncanonicalizedDouble(FloatRegister src, const BaseIndex& addr)
+{
+    ScratchRegisterScope scratch(*this);
+    SecondScratchRegisterScope scratch2(*this);
+    uint32_t scale = Imm32::ShiftOf(addr.scale).value;
+    ma_vstr(src, addr.base, addr.index, scratch, scratch2, scale, addr.offset);
+}
+
+void
+MacroAssembler::storeUncanonicalizedFloat32(FloatRegister src, const Address& addr)
+{
+    ScratchRegisterScope scratch(*this);
+    ma_vstr(src.asSingle(), addr, scratch);
+}
+void
+MacroAssembler::storeUncanonicalizedFloat32(FloatRegister src, const BaseIndex& addr)
+{
+    ScratchRegisterScope scratch(*this);
+    SecondScratchRegisterScope scratch2(*this);
+    uint32_t scale = Imm32::ShiftOf(addr.scale).value;
+    ma_vstr(src.asSingle(), addr.base, addr.index, scratch, scratch2, scale, addr.offset);
+}
+
+void
+MacroAssembler::storeFloat32x3(FloatRegister src, const Address& dest)
+{
+    MOZ_CRASH("NYI");
+}
+void
+MacroAssembler::storeFloat32x3(FloatRegister src, const BaseIndex& dest)
+{
+    MOZ_CRASH("NYI");
+}
+
+void
+MacroAssembler::memoryBarrier(MemoryBarrierBits barrier)
+{
+    // On ARMv6 the optional argument (BarrierST, etc) is ignored.
+    if (barrier == (MembarStoreStore|MembarSynchronizing))
+        ma_dsb(BarrierST);
+    else if (barrier & MembarSynchronizing)
+        ma_dsb();
+    else if (barrier == MembarStoreStore)
+        ma_dmb(BarrierST);
+    else if (barrier)
+        ma_dmb();
+}
+
+// ===============================================================
+// Clamping functions.
+
+void
+MacroAssembler::clampIntToUint8(Register reg)
+{
+    // Look at (reg >> 8) if it is 0, then reg shouldn't be clamped if it is
+    // <0, then we want to clamp to 0, otherwise, we wish to clamp to 255
+    ScratchRegisterScope scratch(*this);
+    as_mov(scratch, asr(reg, 8), SetCC);
+    ma_mov(Imm32(0xff), reg, NotEqual);
+    ma_mov(Imm32(0), reg, Signed);
+}
+
+// ========================================================================
+// wasm support
+
+template <class L>
+void
+MacroAssembler::wasmBoundsCheck(Condition cond, Register index, L label)
+{
+    BufferOffset bo = as_cmp(index, Imm8(0));
+    append(wasm::BoundsCheck(bo.getOffset()));
+
+    as_b(label, cond);
+}
+
+void
+MacroAssembler::wasmPatchBoundsCheck(uint8_t* patchAt, uint32_t limit)
+{
+    Instruction* inst = (Instruction*) patchAt;
+    MOZ_ASSERT(inst->is<InstCMP>());
+    InstCMP* cmp = inst->as<InstCMP>();
+
+    Register index;
+    cmp->extractOp1(&index);
+
+    MOZ_ASSERT(cmp->extractOp2().isImm8());
+
+    Imm8 imm8 = Imm8(limit);
+    MOZ_RELEASE_ASSERT(!imm8.invalid());
+
+    *inst = InstALU(InvalidReg, index, imm8, OpCmp, SetCC, Always);
+    // Don't call Auto Flush Cache; the wasm caller has done this for us.
+}
+
+//}}} check_macroassembler_style
+// ===============================================================
+
+void
+MacroAssemblerARMCompat::incrementInt32Value(const Address& addr)
+{
+    asMasm().add32(Imm32(1), ToPayload(addr));
+}
+
+} // namespace jit
+} // namespace js
+
+#endif /* jit_arm_MacroAssembler_arm_inl_h */
diff --git a/js/src/jit/arm/MacroAssembler-arm.cpp b/js/src/jit/arm/MacroAssembler-arm.cpp
new file mode 100644
index 0000000000..c6e627db68
--- /dev/null
+++ b/js/src/jit/arm/MacroAssembler-arm.cpp
@@ -0,0 +1,5559 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "jit/arm/MacroAssembler-arm.h"
+
+#include "mozilla/Attributes.h"
+#include "mozilla/Casting.h"
+#include "mozilla/DebugOnly.h"
+#include "mozilla/MathAlgorithms.h"
+
+#include "jit/arm/Simulator-arm.h"
+#include "jit/Bailouts.h"
+#include "jit/BaselineFrame.h"
+#include "jit/JitFrames.h"
+#include "jit/MacroAssembler.h"
+#include "jit/MoveEmitter.h"
+
+#include "jit/MacroAssembler-inl.h"
+
+using namespace js;
+using namespace jit;
+
+using mozilla::Abs;
+using mozilla::BitwiseCast;
+
+bool
+isValueDTRDCandidate(ValueOperand& val)
+{
+    // In order to be used for a DTRD memory function, the two target registers
+    // need to be a) Adjacent, with the tag larger than the payload, and b)
+    // Aligned to a multiple of two.
+    if ((val.typeReg().code() != (val.payloadReg().code() + 1)))
+        return false;
+    if ((val.payloadReg().code() & 1) != 0)
+        return false;
+    return true;
+}
+
+void
+MacroAssemblerARM::convertBoolToInt32(Register source, Register dest)
+{
+    // Note that C++ bool is only 1 byte, so zero extend it to clear the
+    // higher-order bits.
+    as_and(dest, source, Imm8(0xff));
+}
+
+void
+MacroAssemblerARM::convertInt32ToDouble(Register src, FloatRegister dest_)
+{
+    // Direct conversions aren't possible.
+    VFPRegister dest = VFPRegister(dest_);
+    as_vxfer(src, InvalidReg, dest.sintOverlay(), CoreToFloat);
+    as_vcvt(dest, dest.sintOverlay());
+}
+
+void
+MacroAssemblerARM::convertInt32ToDouble(const Address& src, FloatRegister dest)
+{
+    ScratchDoubleScope scratch(asMasm());
+    SecondScratchRegisterScope scratch2(asMasm());
+    ma_vldr(src, scratch, scratch2);
+    as_vcvt(dest, VFPRegister(scratch).sintOverlay());
+}
+
+void
+MacroAssemblerARM::convertInt32ToDouble(const BaseIndex& src, FloatRegister dest)
+{
+    Register base = src.base;
+    uint32_t scale = Imm32::ShiftOf(src.scale).value;
+
+    ScratchRegisterScope scratch(asMasm());
+    SecondScratchRegisterScope scratch2(asMasm());
+
+    if (src.offset != 0) {
+        ma_add(base, Imm32(src.offset), scratch, scratch2);
+        base = scratch;
+    }
+    ma_ldr(DTRAddr(base, DtrRegImmShift(src.index, LSL, scale)), scratch);
+    convertInt32ToDouble(scratch, dest);
+}
+
+void
+MacroAssemblerARM::convertUInt32ToDouble(Register src, FloatRegister dest_)
+{
+    // Direct conversions aren't possible.
+    VFPRegister dest = VFPRegister(dest_);
+    as_vxfer(src, InvalidReg, dest.uintOverlay(), CoreToFloat);
+    as_vcvt(dest, dest.uintOverlay());
+}
+
+static const double TO_DOUBLE_HIGH_SCALE = 0x100000000;
+
+bool
+MacroAssemblerARMCompat::convertUInt64ToDoubleNeedsTemp()
+{
+    return false;
+}
+
+void
+MacroAssemblerARMCompat::convertUInt64ToDouble(Register64 src, FloatRegister dest, Register temp)
+{
+    MOZ_ASSERT(temp == Register::Invalid());
+    ScratchDoubleScope scratchDouble(asMasm());
+
+    convertUInt32ToDouble(src.high, dest);
+    {
+        ScratchRegisterScope scratch(asMasm());
+        movePtr(ImmPtr(&TO_DOUBLE_HIGH_SCALE), scratch);
+        ma_vldr(Operand(Address(scratch, 0)).toVFPAddr(), scratchDouble);
+    }
+    asMasm().mulDouble(scratchDouble, dest);
+    convertUInt32ToDouble(src.low, scratchDouble);
+    asMasm().addDouble(scratchDouble, dest);
+}
+
+void
+MacroAssemblerARM::convertUInt32ToFloat32(Register src, FloatRegister dest_)
+{
+    // Direct conversions aren't possible.
+    VFPRegister dest = VFPRegister(dest_);
+    as_vxfer(src, InvalidReg, dest.uintOverlay(), CoreToFloat);
+    as_vcvt(VFPRegister(dest).singleOverlay(), dest.uintOverlay());
+}
+
+void MacroAssemblerARM::convertDoubleToFloat32(FloatRegister src, FloatRegister dest,
+                                               Condition c)
+{
+    as_vcvt(VFPRegister(dest).singleOverlay(), VFPRegister(src), false, c);
+}
+
+// Checks whether a double is representable as a 32-bit integer. If so, the
+// integer is written to the output register. Otherwise, a bailout is taken to
+// the given snapshot. This function overwrites the scratch float register.
+void
+MacroAssemblerARM::convertDoubleToInt32(FloatRegister src, Register dest,
+                                        Label* fail, bool negativeZeroCheck)
+{
+    // Convert the floating point value to an integer, if it did not fit, then
+    // when we convert it *back* to a float, it will have a different value,
+    // which we can test.
+    ScratchDoubleScope scratchDouble(asMasm());
+    ScratchRegisterScope scratch(asMasm());
+
+    FloatRegister scratchSIntReg = scratchDouble.sintOverlay();
+
+    ma_vcvt_F64_I32(src, scratchSIntReg);
+    // Move the value into the dest register.
+    ma_vxfer(scratchSIntReg, dest);
+    ma_vcvt_I32_F64(scratchSIntReg, scratchDouble);
+    ma_vcmp(src, scratchDouble);
+    as_vmrs(pc);
+    ma_b(fail, Assembler::VFP_NotEqualOrUnordered);
+
+    if (negativeZeroCheck) {
+        as_cmp(dest, Imm8(0));
+        // Test and bail for -0.0, when integer result is 0. Move the top word
+        // of the double into the output reg, if it is non-zero, then the
+        // original value was -0.0.
+        as_vxfer(dest, InvalidReg, src, FloatToCore, Assembler::Equal, 1);
+        ma_cmp(dest, Imm32(0x80000000), scratch, Assembler::Equal);
+        ma_b(fail, Assembler::Equal);
+    }
+}
+
+// Checks whether a float32 is representable as a 32-bit integer. If so, the
+// integer is written to the output register. Otherwise, a bailout is taken to
+// the given snapshot. This function overwrites the scratch float register.
+void
+MacroAssemblerARM::convertFloat32ToInt32(FloatRegister src, Register dest,
+                                         Label* fail, bool negativeZeroCheck)
+{
+    // Converting the floating point value to an integer and then converting it
+    // back to a float32 would not work, as float to int32 conversions are
+    // clamping (e.g. float(INT32_MAX + 1) would get converted into INT32_MAX
+    // and then back to float(INT32_MAX + 1)).  If this ever happens, we just
+    // bail out.
+    ScratchFloat32Scope scratchFloat(asMasm());
+    ScratchRegisterScope scratch(asMasm());
+
+    FloatRegister ScratchSIntReg = scratchFloat.sintOverlay();
+    ma_vcvt_F32_I32(src, ScratchSIntReg);
+
+    // Store the result
+    ma_vxfer(ScratchSIntReg, dest);
+
+    ma_vcvt_I32_F32(ScratchSIntReg, scratchFloat);
+    ma_vcmp(src, scratchFloat);
+    as_vmrs(pc);
+    ma_b(fail, Assembler::VFP_NotEqualOrUnordered);
+
+    // Bail out in the clamped cases.
+    ma_cmp(dest, Imm32(0x7fffffff), scratch);
+    ma_cmp(dest, Imm32(0x80000000), scratch, Assembler::NotEqual);
+    ma_b(fail, Assembler::Equal);
+
+    if (negativeZeroCheck) {
+        as_cmp(dest, Imm8(0));
+        // Test and bail for -0.0, when integer result is 0. Move the float into
+        // the output reg, and if it is non-zero then the original value was
+        // -0.0
+        as_vxfer(dest, InvalidReg, VFPRegister(src).singleOverlay(), FloatToCore, Assembler::Equal, 0);
+        ma_cmp(dest, Imm32(0x80000000), scratch, Assembler::Equal);
+        ma_b(fail, Assembler::Equal);
+    }
+}
+
+void
+MacroAssemblerARM::convertFloat32ToDouble(FloatRegister src, FloatRegister dest)
+{
+    MOZ_ASSERT(dest.isDouble());
+    MOZ_ASSERT(src.isSingle());
+    as_vcvt(VFPRegister(dest), VFPRegister(src).singleOverlay());
+}
+
+void
+MacroAssemblerARM::convertInt32ToFloat32(Register src, FloatRegister dest)
+{
+    // Direct conversions aren't possible.
+    as_vxfer(src, InvalidReg, dest.sintOverlay(), CoreToFloat);
+    as_vcvt(dest.singleOverlay(), dest.sintOverlay());
+}
+
+void
+MacroAssemblerARM::convertInt32ToFloat32(const Address& src, FloatRegister dest)
+{
+    ScratchFloat32Scope scratch(asMasm());
+    SecondScratchRegisterScope scratch2(asMasm());
+    ma_vldr(src, scratch, scratch2);
+    as_vcvt(dest, VFPRegister(scratch).sintOverlay());
+}
+
+bool
+MacroAssemblerARM::alu_dbl(Register src1, Imm32 imm, Register dest, ALUOp op,
+                           SBit s, Condition c)
+{
+    if ((s == SetCC && ! condsAreSafe(op)) || !can_dbl(op))
+        return false;
+
+    ALUOp interop = getDestVariant(op);
+    Imm8::TwoImm8mData both = Imm8::EncodeTwoImms(imm.value);
+    if (both.fst().invalid())
+        return false;
+
+    // For the most part, there is no good reason to set the condition codes for
+    // the first instruction. We can do better things if the second instruction
+    // doesn't have a dest, such as check for overflow by doing first operation
+    // don't do second operation if first operation overflowed. This preserves
+    // the overflow condition code. Unfortunately, it is horribly brittle.
+    as_alu(dest, src1, Operand2(both.fst()), interop, LeaveCC, c);
+    as_alu(dest, dest, Operand2(both.snd()), op, s, c);
+    return true;
+}
+
+void
+MacroAssemblerARM::ma_alu(Register src1, Imm32 imm, Register dest, AutoRegisterScope& scratch,
+                          ALUOp op, SBit s, Condition c)
+{
+    // ma_mov should be used for moves.
+    MOZ_ASSERT(op != OpMov);
+    MOZ_ASSERT(op != OpMvn);
+    MOZ_ASSERT(src1 != scratch);
+
+    // As it turns out, if you ask for a compare-like instruction you *probably*
+    // want it to set condition codes.
+    MOZ_ASSERT_IF(dest == InvalidReg, s == SetCC);
+
+    // The operator gives us the ability to determine how this can be used.
+    Imm8 imm8 = Imm8(imm.value);
+    // One instruction: If we can encode it using an imm8m, then do so.
+    if (!imm8.invalid()) {
+        as_alu(dest, src1, imm8, op, s, c);
+        return;
+    }
+
+    // One instruction, negated:
+    Imm32 negImm = imm;
+    Register negDest;
+    ALUOp negOp = ALUNeg(op, dest, scratch, &negImm, &negDest);
+    Imm8 negImm8 = Imm8(negImm.value);
+    // 'add r1, r2, -15' can be replaced with 'sub r1, r2, 15'.
+    // The dest can be replaced (InvalidReg => scratch).
+    // This is useful if we wish to negate tst. tst has an invalid (aka not
+    // used) dest, but its negation bic requires a dest.
+    if (negOp != OpInvalid && !negImm8.invalid()) {
+        as_alu(negDest, src1, negImm8, negOp, s, c);
+        return;
+    }
+
+    // Start by attempting to generate a two instruction form. Some things
+    // cannot be made into two-inst forms correctly. Namely, adds dest, src,
+    // 0xffff. Since we want the condition codes (and don't know which ones
+    // will be checked), we need to assume that the overflow flag will be
+    // checked and add{,s} dest, src, 0xff00; add{,s} dest, dest, 0xff is not
+    // guaranteed to set the overflof flag the same as the (theoretical) one
+    // instruction variant.
+    if (alu_dbl(src1, imm, dest, op, s, c))
+        return;
+
+    // And try with its negative.
+    if (negOp != OpInvalid && alu_dbl(src1, negImm, negDest, negOp, s, c))
+        return;
+
+    ma_mov(imm, scratch, c);
+    as_alu(dest, src1, O2Reg(scratch), op, s, c);
+}
+
+void
+MacroAssemblerARM::ma_alu(Register src1, Operand op2, Register dest, ALUOp op,
+                          SBit s, Assembler::Condition c)
+{
+    MOZ_ASSERT(op2.tag() == Operand::Tag::OP2);
+    as_alu(dest, src1, op2.toOp2(), op, s, c);
+}
+
+void
+MacroAssemblerARM::ma_alu(Register src1, Operand2 op2, Register dest, ALUOp op, SBit s, Condition c)
+{
+    as_alu(dest, src1, op2, op, s, c);
+}
+
+void
+MacroAssemblerARM::ma_nop()
+{
+    as_nop();
+}
+
+void
+MacroAssemblerARM::ma_movPatchable(Imm32 imm_, Register dest, Assembler::Condition c)
+{
+    int32_t imm = imm_.value;
+    if (HasMOVWT()) {
+        as_movw(dest, Imm16(imm & 0xffff), c);
+        as_movt(dest, Imm16(imm >> 16 & 0xffff), c);
+    } else {
+        as_Imm32Pool(dest, imm, c);
+    }
+}
+
+void
+MacroAssemblerARM::ma_movPatchable(ImmPtr imm, Register dest, Assembler::Condition c)
+{
+    ma_movPatchable(Imm32(int32_t(imm.value)), dest, c);
+}
+
+/* static */ void
+MacroAssemblerARM::ma_mov_patch(Imm32 imm_, Register dest, Assembler::Condition c,
+                                RelocStyle rs, Instruction* i)
+{
+    MOZ_ASSERT(i);
+    int32_t imm = imm_.value;
+
+    // Make sure the current instruction is not an artificial guard inserted
+    // by the assembler buffer.
+    i = i->skipPool();
+
+    switch(rs) {
+      case L_MOVWT:
+        Assembler::as_movw_patch(dest, Imm16(imm & 0xffff), c, i);
+        i = i->next();
+        Assembler::as_movt_patch(dest, Imm16(imm >> 16 & 0xffff), c, i);
+        break;
+      case L_LDR:
+        Assembler::WritePoolEntry(i, c, imm);
+        break;
+    }
+}
+
+/* static */ void
+MacroAssemblerARM::ma_mov_patch(ImmPtr imm, Register dest, Assembler::Condition c,
+                                RelocStyle rs, Instruction* i)
+{
+    ma_mov_patch(Imm32(int32_t(imm.value)), dest, c, rs, i);
+}
+
+void
+MacroAssemblerARM::ma_mov(Register src, Register dest, SBit s, Assembler::Condition c)
+{
+    if (s == SetCC || dest != src)
+        as_mov(dest, O2Reg(src), s, c);
+}
+
+void
+MacroAssemblerARM::ma_mov(Imm32 imm, Register dest, Assembler::Condition c)
+{
+    // Try mov with Imm8 operand.
+    Imm8 imm8 = Imm8(imm.value);
+    if (!imm8.invalid()) {
+        as_alu(dest, InvalidReg, imm8, OpMov, LeaveCC, c);
+        return;
+    }
+
+    // Try mvn with Imm8 operand.
+    Imm8 negImm8 = Imm8(~imm.value);
+    if (!negImm8.invalid()) {
+        as_alu(dest, InvalidReg, negImm8, OpMvn, LeaveCC, c);
+        return;
+    }
+
+    // Try movw/movt.
+    if (HasMOVWT()) {
+        // ARMv7 supports movw/movt. movw zero-extends its 16 bit argument,
+        // so we can set the register this way. movt leaves the bottom 16
+        // bits in tact, so we always need a movw.
+        as_movw(dest, Imm16(imm.value & 0xffff), c);
+        if (uint32_t(imm.value) >> 16)
+            as_movt(dest, Imm16(uint32_t(imm.value) >> 16), c);
+        return;
+    }
+
+    // If we don't have movw/movt, we need a load.
+    as_Imm32Pool(dest, imm.value, c);
+}
+
+void
+MacroAssemblerARM::ma_mov(ImmWord imm, Register dest, Assembler::Condition c)
+{
+    ma_mov(Imm32(imm.value), dest, c);
+}
+
+void
+MacroAssemblerARM::ma_mov(ImmGCPtr ptr, Register dest)
+{
+    // As opposed to x86/x64 version, the data relocation has to be executed
+    // before to recover the pointer, and not after.
+    writeDataRelocation(ptr);
+    ma_movPatchable(Imm32(uintptr_t(ptr.value)), dest, Always);
+}
+
+// Shifts (just a move with a shifting op2)
+void
+MacroAssemblerARM::ma_lsl(Imm32 shift, Register src, Register dst)
+{
+    as_mov(dst, lsl(src, shift.value));
+}
+
+void
+MacroAssemblerARM::ma_lsr(Imm32 shift, Register src, Register dst)
+{
+    as_mov(dst, lsr(src, shift.value));
+}
+
+void
+MacroAssemblerARM::ma_asr(Imm32 shift, Register src, Register dst)
+{
+    as_mov(dst, asr(src, shift.value));
+}
+
+void
+MacroAssemblerARM::ma_ror(Imm32 shift, Register src, Register dst)
+{
+    as_mov(dst, ror(src, shift.value));
+}
+
+void
+MacroAssemblerARM::ma_rol(Imm32 shift, Register src, Register dst)
+{
+    as_mov(dst, rol(src, shift.value));
+}
+
+// Shifts (just a move with a shifting op2)
+void
+MacroAssemblerARM::ma_lsl(Register shift, Register src, Register dst)
+{
+    as_mov(dst, lsl(src, shift));
+}
+
+void
+MacroAssemblerARM::ma_lsr(Register shift, Register src, Register dst)
+{
+    as_mov(dst, lsr(src, shift));
+}
+
+void
+MacroAssemblerARM::ma_asr(Register shift, Register src, Register dst)
+{
+    as_mov(dst, asr(src, shift));
+}
+
+void
+MacroAssemblerARM::ma_ror(Register shift, Register src, Register dst)
+{
+    as_mov(dst, ror(src, shift));
+}
+
+void
+MacroAssemblerARM::ma_rol(Register shift, Register src, Register dst, AutoRegisterScope& scratch)
+{
+    as_rsb(scratch, shift, Imm8(32));
+    as_mov(dst, ror(src, scratch));
+}
+
+// Move not (dest <- ~src)
+void
+MacroAssemblerARM::ma_mvn(Register src1, Register dest, SBit s, Assembler::Condition c)
+{
+    as_alu(dest, InvalidReg, O2Reg(src1), OpMvn, s, c);
+}
+
+// Negate (dest <- -src), src is a register, rather than a general op2.
+void
+MacroAssemblerARM::ma_neg(Register src1, Register dest, SBit s, Assembler::Condition c)
+{
+    as_rsb(dest, src1, Imm8(0), s, c);
+}
+
+// And.
+void
+MacroAssemblerARM::ma_and(Register src, Register dest, SBit s, Assembler::Condition c)
+{
+    ma_and(dest, src, dest);
+}
+
+void
+MacroAssemblerARM::ma_and(Register src1, Register src2, Register dest,
+                          SBit s, Assembler::Condition c)
+{
+    as_and(dest, src1, O2Reg(src2), s, c);
+}
+
+void
+MacroAssemblerARM::ma_and(Imm32 imm, Register dest, AutoRegisterScope& scratch,
+                          SBit s, Assembler::Condition c)
+{
+    ma_alu(dest, imm, dest, scratch, OpAnd, s, c);
+}
+
+void
+MacroAssemblerARM::ma_and(Imm32 imm, Register src1, Register dest, AutoRegisterScope& scratch,
+                          SBit s, Assembler::Condition c)
+{
+    ma_alu(src1, imm, dest, scratch, OpAnd, s, c);
+}
+
+// Bit clear (dest <- dest & ~imm) or (dest <- src1 & ~src2).
+void
+MacroAssemblerARM::ma_bic(Imm32 imm, Register dest, AutoRegisterScope& scratch, SBit s, Assembler::Condition c)
+{
+    ma_alu(dest, imm, dest, scratch, OpBic, s, c);
+}
+
+// Exclusive or.
+void
+MacroAssemblerARM::ma_eor(Register src, Register dest, SBit s, Assembler::Condition c)
+{
+    ma_eor(dest, src, dest, s, c);
+}
+
+void
+MacroAssemblerARM::ma_eor(Register src1, Register src2, Register dest,
+                          SBit s, Assembler::Condition c)
+{
+    as_eor(dest, src1, O2Reg(src2), s, c);
+}
+
+void
+MacroAssemblerARM::ma_eor(Imm32 imm, Register dest, AutoRegisterScope& scratch, SBit s, Assembler::Condition c)
+{
+    ma_alu(dest, imm, dest, scratch, OpEor, s, c);
+}
+
+void
+MacroAssemblerARM::ma_eor(Imm32 imm, Register src1, Register dest, AutoRegisterScope& scratch,
+       SBit s, Assembler::Condition c)
+{
+    ma_alu(src1, imm, dest, scratch, OpEor, s, c);
+}
+
+// Or.
+void
+MacroAssemblerARM::ma_orr(Register src, Register dest, SBit s, Assembler::Condition c)
+{
+    ma_orr(dest, src, dest, s, c);
+}
+
+void
+MacroAssemblerARM::ma_orr(Register src1, Register src2, Register dest,
+                          SBit s, Assembler::Condition c)
+{
+    as_orr(dest, src1, O2Reg(src2), s, c);
+}
+
+void
+MacroAssemblerARM::ma_orr(Imm32 imm, Register dest, AutoRegisterScope& scratch, SBit s, Assembler::Condition c)
+{
+    ma_alu(dest, imm, dest, scratch, OpOrr, s, c);
+}
+
+void
+MacroAssemblerARM::ma_orr(Imm32 imm, Register src1, Register dest, AutoRegisterScope& scratch,
+                          SBit s, Assembler::Condition c)
+{
+    ma_alu(src1, imm, dest, scratch, OpOrr, s, c);
+}
+
+// Arithmetic-based ops.
+// Add with carry.
+void
+MacroAssemblerARM::ma_adc(Imm32 imm, Register dest, AutoRegisterScope& scratch, SBit s, Condition c)
+{
+    ma_alu(dest, imm, dest, scratch, OpAdc, s, c);
+}
+
+void
+MacroAssemblerARM::ma_adc(Register src, Register dest, SBit s, Condition c)
+{
+    as_alu(dest, dest, O2Reg(src), OpAdc, s, c);
+}
+
+void
+MacroAssemblerARM::ma_adc(Register src1, Register src2, Register dest, SBit s, Condition c)
+{
+    as_alu(dest, src1, O2Reg(src2), OpAdc, s, c);
+}
+
+// Add.
+void
+MacroAssemblerARM::ma_add(Imm32 imm, Register dest, AutoRegisterScope& scratch, SBit s, Condition c)
+{
+    ma_alu(dest, imm, dest, scratch, OpAdd, s, c);
+}
+
+void
+MacroAssemblerARM::ma_add(Register src1, Register dest, SBit s, Condition c)
+{
+    ma_alu(dest, O2Reg(src1), dest, OpAdd, s, c);
+}
+
+void
+MacroAssemblerARM::ma_add(Register src1, Register src2, Register dest, SBit s, Condition c)
+{
+    as_alu(dest, src1, O2Reg(src2), OpAdd, s, c);
+}
+
+void
+MacroAssemblerARM::ma_add(Register src1, Operand op, Register dest, SBit s, Condition c)
+{
+    ma_alu(src1, op, dest, OpAdd, s, c);
+}
+
+void
+MacroAssemblerARM::ma_add(Register src1, Imm32 op, Register dest, AutoRegisterScope& scratch, SBit s, Condition c)
+{
+    ma_alu(src1, op, dest, scratch, OpAdd, s, c);
+}
+
+// Subtract with carry.
+void
+MacroAssemblerARM::ma_sbc(Imm32 imm, Register dest, AutoRegisterScope& scratch, SBit s, Condition c)
+{
+    ma_alu(dest, imm, dest, scratch, OpSbc, s, c);
+}
+
+void
+MacroAssemblerARM::ma_sbc(Register src1, Register dest, SBit s, Condition c)
+{
+    as_alu(dest, dest, O2Reg(src1), OpSbc, s, c);
+}
+
+void
+MacroAssemblerARM::ma_sbc(Register src1, Register src2, Register dest, SBit s, Condition c)
+{
+    as_alu(dest, src1, O2Reg(src2), OpSbc, s, c);
+}
+
+// Subtract.
+void
+MacroAssemblerARM::ma_sub(Imm32 imm, Register dest, AutoRegisterScope& scratch, SBit s, Condition c)
+{
+    ma_alu(dest, imm, dest, scratch, OpSub, s, c);
+}
+
+void
+MacroAssemblerARM::ma_sub(Register src1, Register dest, SBit s, Condition c)
+{
+    ma_alu(dest, Operand(src1), dest, OpSub, s, c);
+}
+
+void
+MacroAssemblerARM::ma_sub(Register src1, Register src2, Register dest, SBit s, Condition c)
+{
+    ma_alu(src1, Operand(src2), dest, OpSub, s, c);
+}
+
+void
+MacroAssemblerARM::ma_sub(Register src1, Operand op, Register dest, SBit s, Condition c)
+{
+    ma_alu(src1, op, dest, OpSub, s, c);
+}
+
+void
+MacroAssemblerARM::ma_sub(Register src1, Imm32 op, Register dest, AutoRegisterScope& scratch, SBit s, Condition c)
+{
+    ma_alu(src1, op, dest, scratch, OpSub, s, c);
+}
+
+// Reverse subtract.
+void
+MacroAssemblerARM::ma_rsb(Imm32 imm, Register dest, AutoRegisterScope& scratch, SBit s, Condition c)
+{
+    ma_alu(dest, imm, dest, scratch, OpRsb, s, c);
+}
+
+void
+MacroAssemblerARM::ma_rsb(Register src1, Register dest, SBit s, Condition c)
+{
+    as_alu(dest, src1, O2Reg(dest), OpRsb, s, c);
+}
+
+void
+MacroAssemblerARM::ma_rsb(Register src1, Register src2, Register dest, SBit s, Condition c)
+{
+    as_alu(dest, src1, O2Reg(src2), OpRsb, s, c);
+}
+
+void
+MacroAssemblerARM::ma_rsb(Register src1, Imm32 op2, Register dest, AutoRegisterScope& scratch, SBit s, Condition c)
+{
+    ma_alu(src1, op2, dest, scratch, OpRsb, s, c);
+}
+
+// Reverse subtract with carry.
+void
+MacroAssemblerARM::ma_rsc(Imm32 imm, Register dest, AutoRegisterScope& scratch, SBit s, Condition c)
+{
+    ma_alu(dest, imm, dest, scratch, OpRsc, s, c);
+}
+
+void
+MacroAssemblerARM::ma_rsc(Register src1, Register dest, SBit s, Condition c)
+{
+    as_alu(dest, dest, O2Reg(src1), OpRsc, s, c);
+}
+
+void
+MacroAssemblerARM::ma_rsc(Register src1, Register src2, Register dest, SBit s, Condition c)
+{
+    as_alu(dest, src1, O2Reg(src2), OpRsc, s, c);
+}
+
+// Compares/tests.
+// Compare negative (sets condition codes as src1 + src2 would).
+void
+MacroAssemblerARM::ma_cmn(Register src1, Imm32 imm, AutoRegisterScope& scratch, Condition c)
+{
+    ma_alu(src1, imm, InvalidReg, scratch, OpCmn, SetCC, c);
+}
+
+void
+MacroAssemblerARM::ma_cmn(Register src1, Register src2, Condition c)
+{
+    as_alu(InvalidReg, src2, O2Reg(src1), OpCmn, SetCC, c);
+}
+
+void
+MacroAssemblerARM::ma_cmn(Register src1, Operand op, Condition c)
+{
+    MOZ_CRASH("Feature NYI");
+}
+
+// Compare (src - src2).
+void
+MacroAssemblerARM::ma_cmp(Register src1, Imm32 imm, AutoRegisterScope& scratch, Condition c)
+{
+    ma_alu(src1, imm, InvalidReg, scratch, OpCmp, SetCC, c);
+}
+
+void
+MacroAssemblerARM::ma_cmp(Register src1, ImmTag tag, Condition c)
+{
+    // ImmTag comparisons can always be done without use of a scratch register.
+    Imm8 negtag = Imm8(-tag.value);
+    MOZ_ASSERT(!negtag.invalid());
+    as_cmn(src1, negtag, c);
+}
+
+void
+MacroAssemblerARM::ma_cmp(Register src1, ImmWord ptr, AutoRegisterScope& scratch, Condition c)
+{
+    ma_cmp(src1, Imm32(ptr.value), scratch, c);
+}
+
+void
+MacroAssemblerARM::ma_cmp(Register src1, ImmGCPtr ptr, AutoRegisterScope& scratch, Condition c)
+{
+    ma_mov(ptr, scratch);
+    ma_cmp(src1, scratch, c);
+}
+
+void
+MacroAssemblerARM::ma_cmp(Register src1, Operand op, AutoRegisterScope& scratch,
+                          AutoRegisterScope& scratch2, Condition c)
+{
+    switch (op.tag()) {
+      case Operand::Tag::OP2:
+        as_cmp(src1, op.toOp2(), c);
+        break;
+      case Operand::Tag::MEM:
+        ma_ldr(op.toAddress(), scratch, scratch2);
+        as_cmp(src1, O2Reg(scratch), c);
+        break;
+      default:
+        MOZ_CRASH("trying to compare FP and integer registers");
+    }
+}
+
+void
+MacroAssemblerARM::ma_cmp(Register src1, Register src2, Condition c)
+{
+    as_cmp(src1, O2Reg(src2), c);
+}
+
+// Test for equality, (src1 ^ src2).
+void
+MacroAssemblerARM::ma_teq(Register src1, Imm32 imm, AutoRegisterScope& scratch, Condition c)
+{
+    ma_alu(src1, imm, InvalidReg, scratch, OpTeq, SetCC, c);
+}
+
+void
+MacroAssemblerARM::ma_teq(Register src1, Register src2, Condition c)
+{
+    as_tst(src1, O2Reg(src2), c);
+}
+
+void
+MacroAssemblerARM::ma_teq(Register src1, Operand op, Condition c)
+{
+    as_teq(src1, op.toOp2(), c);
+}
+
+// Test (src1 & src2).
+void
+MacroAssemblerARM::ma_tst(Register src1, Imm32 imm, AutoRegisterScope& scratch, Condition c)
+{
+    ma_alu(src1, imm, InvalidReg, scratch, OpTst, SetCC, c);
+}
+
+void
+MacroAssemblerARM::ma_tst(Register src1, Register src2, Condition c)
+{
+    as_tst(src1, O2Reg(src2), c);
+}
+
+void
+MacroAssemblerARM::ma_tst(Register src1, Operand op, Condition c)
+{
+    as_tst(src1, op.toOp2(), c);
+}
+
+void
+MacroAssemblerARM::ma_mul(Register src1, Register src2, Register dest)
+{
+    as_mul(dest, src1, src2);
+}
+
+void
+MacroAssemblerARM::ma_mul(Register src1, Imm32 imm, Register dest, AutoRegisterScope& scratch)
+{
+    ma_mov(imm, scratch);
+    as_mul(dest, src1, scratch);
+}
+
+Assembler::Condition
+MacroAssemblerARM::ma_check_mul(Register src1, Register src2, Register dest,
+                                AutoRegisterScope& scratch, Condition cond)
+{
+    // TODO: this operation is illegal on armv6 and earlier
+    // if src2 == scratch or src2 == dest.
+    if (cond == Equal || cond == NotEqual) {
+        as_smull(scratch, dest, src1, src2, SetCC);
+        return cond;
+    }
+
+    if (cond == Overflow) {
+        as_smull(scratch, dest, src1, src2);
+        as_cmp(scratch, asr(dest, 31));
+        return NotEqual;
+    }
+
+    MOZ_CRASH("Condition NYI");
+}
+
+Assembler::Condition
+MacroAssemblerARM::ma_check_mul(Register src1, Imm32 imm, Register dest,
+                                AutoRegisterScope& scratch, Condition cond)
+{
+    ma_mov(imm, scratch);
+
+    if (cond == Equal || cond == NotEqual) {
+        as_smull(scratch, dest, scratch, src1, SetCC);
+        return cond;
+    }
+
+    if (cond == Overflow) {
+        as_smull(scratch, dest, scratch, src1);
+        as_cmp(scratch, asr(dest, 31));
+        return NotEqual;
+    }
+
+    MOZ_CRASH("Condition NYI");
+}
+
+void
+MacroAssemblerARM::ma_umull(Register src1, Imm32 imm, Register destHigh, Register destLow,
+                            AutoRegisterScope& scratch)
+{
+    ma_mov(imm, scratch);
+    as_umull(destHigh, destLow, src1, scratch);
+}
+
+void
+MacroAssemblerARM::ma_umull(Register src1, Register src2, Register destHigh, Register destLow)
+{
+    as_umull(destHigh, destLow, src1, src2);
+}
+
+void
+MacroAssemblerARM::ma_mod_mask(Register src, Register dest, Register hold, Register tmp,
+                               AutoRegisterScope& scratch, AutoRegisterScope& scratch2, int32_t shift)
+{
+    // We wish to compute x % (1<<y) - 1 for a known constant, y.
+    //
+    // 1. Let b = (1<<y) and C = (1<<y)-1, then think of the 32 bit dividend as
+    // a number in base b, namely c_0*1 + c_1*b + c_2*b^2 ... c_n*b^n
+    //
+    // 2. Since both addition and multiplication commute with modulus:
+    //   x % C == (c_0 + c_1*b + ... + c_n*b^n) % C ==
+    //    (c_0 % C) + (c_1%C) * (b % C) + (c_2 % C) * (b^2 % C)...
+    //
+    // 3. Since b == C + 1, b % C == 1, and b^n % C == 1 the whole thing
+    // simplifies to: c_0 + c_1 + c_2 ... c_n % C
+    //
+    // Each c_n can easily be computed by a shift/bitextract, and the modulus
+    // can be maintained by simply subtracting by C whenever the number gets
+    // over C.
+    int32_t mask = (1 << shift) - 1;
+    Label head;
+
+    // Register 'hold' holds -1 if the value was negative, 1 otherwise. The
+    // scratch reg holds the remaining bits that have not been processed lr
+    // serves as a temporary location to store extracted bits into as well as
+    // holding the trial subtraction as a temp value dest is the accumulator
+    // (and holds the final result)
+    //
+    // Move the whole value into tmp, setting the codition codes so we can muck
+    // with them later.
+    as_mov(tmp, O2Reg(src), SetCC);
+    // Zero out the dest.
+    ma_mov(Imm32(0), dest);
+    // Set the hold appropriately.
+    ma_mov(Imm32(1), hold);
+    ma_mov(Imm32(-1), hold, Signed);
+    as_rsb(tmp, tmp, Imm8(0), SetCC, Signed);
+
+    // Begin the main loop.
+    bind(&head);
+    {
+        // Extract the bottom bits.
+        ma_and(Imm32(mask), tmp, scratch, scratch2);
+        // Add those bits to the accumulator.
+        ma_add(scratch, dest, dest);
+        // Do a trial subtraction, this is the same operation as cmp, but we store
+        // the dest.
+        ma_sub(dest, Imm32(mask), scratch, scratch2, SetCC);
+        // If (sum - C) > 0, store sum - C back into sum, thus performing a modulus.
+        ma_mov(scratch, dest, LeaveCC, NotSigned);
+        // Get rid of the bits that we extracted before, and set the condition codes.
+        as_mov(tmp, lsr(tmp, shift), SetCC);
+        // If the shift produced zero, finish, otherwise, continue in the loop.
+        ma_b(&head, NonZero);
+    }
+
+    // Check the hold to see if we need to negate the result. Hold can only be
+    // 1 or -1, so this will never set the 0 flag.
+    as_cmp(hold, Imm8(0));
+    // If the hold was non-zero, negate the result to be in line with what JS
+    // wants this will set the condition codes if we try to negate.
+    as_rsb(dest, dest, Imm8(0), SetCC, Signed);
+    // Since the Zero flag is not set by the compare, we can *only* set the Zero
+    // flag in the rsb, so Zero is set iff we negated zero (e.g. the result of
+    // the computation was -0.0).
+}
+
+void
+MacroAssemblerARM::ma_smod(Register num, Register div, Register dest, AutoRegisterScope& scratch)
+{
+    as_sdiv(scratch, num, div);
+    as_mls(dest, num, scratch, div);
+}
+
+void
+MacroAssemblerARM::ma_umod(Register num, Register div, Register dest, AutoRegisterScope& scratch)
+{
+    as_udiv(scratch, num, div);
+    as_mls(dest, num, scratch, div);
+}
+
+// Division
+void
+MacroAssemblerARM::ma_sdiv(Register num, Register div, Register dest, Condition cond)
+{
+    as_sdiv(dest, num, div, cond);
+}
+
+void
+MacroAssemblerARM::ma_udiv(Register num, Register div, Register dest, Condition cond)
+{
+    as_udiv(dest, num, div, cond);
+}
+
+// Miscellaneous instructions.
+void
+MacroAssemblerARM::ma_clz(Register src, Register dest, Condition cond)
+{
+    as_clz(dest, src, cond);
+}
+
+void
+MacroAssemblerARM::ma_ctz(Register src, Register dest, AutoRegisterScope& scratch)
+{
+    // int c = __clz(a & -a);
+    // return a ? 31 - c : c;
+    as_rsb(scratch, src, Imm8(0), SetCC);
+    as_and(dest, src, O2Reg(scratch), LeaveCC);
+    as_clz(dest, dest);
+    as_rsb(dest, dest, Imm8(0x1F), LeaveCC, Assembler::NotEqual);
+}
+
+// Memory.
+// Shortcut for when we know we're transferring 32 bits of data.
+void
+MacroAssemblerARM::ma_dtr(LoadStore ls, Register rn, Imm32 offset, Register rt,
+                          AutoRegisterScope& scratch, Index mode, Assembler::Condition cc)
+{
+    ma_dataTransferN(ls, 32, true, rn, offset, rt, scratch, mode, cc);
+}
+
+void
+MacroAssemblerARM::ma_dtr(LoadStore ls, Register rt, const Address& addr,
+                          AutoRegisterScope& scratch, Index mode, Condition cc)
+{
+    ma_dataTransferN(ls, 32, true, addr.base, Imm32(addr.offset), rt, scratch, mode, cc);
+}
+
+void
+MacroAssemblerARM::ma_str(Register rt, DTRAddr addr, Index mode, Condition cc)
+{
+    as_dtr(IsStore, 32, mode, rt, addr, cc);
+}
+
+void
+MacroAssemblerARM::ma_str(Register rt, const Address& addr, AutoRegisterScope& scratch, Index mode, Condition cc)
+{
+    ma_dtr(IsStore, rt, addr, scratch, mode, cc);
+}
+
+void
+MacroAssemblerARM::ma_strd(Register rt, DebugOnly<Register> rt2, EDtrAddr addr, Index mode, Condition cc)
+{
+    MOZ_ASSERT((rt.code() & 1) == 0);
+    MOZ_ASSERT(rt2.value.code() == rt.code() + 1);
+    as_extdtr(IsStore, 64, true, mode, rt, addr, cc);
+}
+
+void
+MacroAssemblerARM::ma_ldr(DTRAddr addr, Register rt, Index mode, Condition cc)
+{
+    as_dtr(IsLoad, 32, mode, rt, addr, cc);
+}
+
+void
+MacroAssemblerARM::ma_ldr(const Address& addr, Register rt, AutoRegisterScope& scratch, Index mode, Condition cc)
+{
+    ma_dtr(IsLoad, rt, addr, scratch, mode, cc);
+}
+
+void
+MacroAssemblerARM::ma_ldrb(DTRAddr addr, Register rt, Index mode, Condition cc)
+{
+    as_dtr(IsLoad, 8, mode, rt, addr, cc);
+}
+
+void
+MacroAssemblerARM::ma_ldrsh(EDtrAddr addr, Register rt, Index mode, Condition cc)
+{
+    as_extdtr(IsLoad, 16, true, mode, rt, addr, cc);
+}
+
+void
+MacroAssemblerARM::ma_ldrh(EDtrAddr addr, Register rt, Index mode, Condition cc)
+{
+    as_extdtr(IsLoad, 16, false, mode, rt, addr, cc);
+}
+
+void
+MacroAssemblerARM::ma_ldrsb(EDtrAddr addr, Register rt, Index mode, Condition cc)
+{
+    as_extdtr(IsLoad, 8, true, mode, rt, addr, cc);
+}
+
+void
+MacroAssemblerARM::ma_ldrd(EDtrAddr addr, Register rt, DebugOnly<Register> rt2,
+                           Index mode, Condition cc)
+{
+    MOZ_ASSERT((rt.code() & 1) == 0);
+    MOZ_ASSERT(rt2.value.code() == rt.code() + 1);
+    MOZ_ASSERT(addr.maybeOffsetRegister() != rt); // Undefined behavior if rm == rt/rt2.
+    MOZ_ASSERT(addr.maybeOffsetRegister() != rt2);
+    as_extdtr(IsLoad, 64, true, mode, rt, addr, cc);
+}
+
+void
+MacroAssemblerARM::ma_strh(Register rt, EDtrAddr addr, Index mode, Condition cc)
+{
+    as_extdtr(IsStore, 16, false, mode, rt, addr, cc);
+}
+
+void
+MacroAssemblerARM::ma_strb(Register rt, DTRAddr addr, Index mode, Condition cc)
+{
+    as_dtr(IsStore, 8, mode, rt, addr, cc);
+}
+
+// Specialty for moving N bits of data, where n == 8,16,32,64.
+BufferOffset
+MacroAssemblerARM::ma_dataTransferN(LoadStore ls, int size, bool IsSigned,
+                                    Register rn, Register rm, Register rt, AutoRegisterScope& scratch,
+                                    Index mode, Assembler::Condition cc, Scale scale)
+{
+    MOZ_ASSERT(size == 8 || size == 16 || size == 32 || size == 64);
+
+    if (size == 32 || (size == 8 && !IsSigned))
+        return as_dtr(ls, size, mode, rt, DTRAddr(rn, DtrRegImmShift(rm, LSL, scale)), cc);
+
+    if (scale != TimesOne) {
+        ma_lsl(Imm32(scale), rm, scratch);
+        rm = scratch;
+    }
+
+    return as_extdtr(ls, size, IsSigned, mode, rt, EDtrAddr(rn, EDtrOffReg(rm)), cc);
+}
+
+// No scratch register is required if scale is TimesOne.
+BufferOffset
+MacroAssemblerARM::ma_dataTransferN(LoadStore ls, int size, bool IsSigned,
+                                    Register rn, Register rm, Register rt,
+                                    Index mode, Assembler::Condition cc)
+{
+    MOZ_ASSERT(size == 8 || size == 16 || size == 32 || size == 64);
+    if (size == 32 || (size == 8 && !IsSigned))
+        return as_dtr(ls, size, mode, rt, DTRAddr(rn, DtrRegImmShift(rm, LSL, TimesOne)), cc);
+    return as_extdtr(ls, size, IsSigned, mode, rt, EDtrAddr(rn, EDtrOffReg(rm)), cc);
+}
+
+
+BufferOffset
+MacroAssemblerARM::ma_dataTransferN(LoadStore ls, int size, bool IsSigned,
+                                    Register rn, Imm32 offset, Register rt, AutoRegisterScope& scratch,
+                                    Index mode, Assembler::Condition cc)
+{
+    MOZ_ASSERT(!(ls == IsLoad && mode == PostIndex && rt == pc),
+               "Large-offset PostIndex loading into PC requires special logic: see ma_popn_pc().");
+
+    int off = offset.value;
+
+    // We can encode this as a standard ldr.
+    if (size == 32 || (size == 8 && !IsSigned) ) {
+        if (off < 4096 && off > -4096) {
+            // This encodes as a single instruction, Emulating mode's behavior
+            // in a multi-instruction sequence is not necessary.
+            return as_dtr(ls, size, mode, rt, DTRAddr(rn, DtrOffImm(off)), cc);
+        }
+
+        // We cannot encode this offset in a single ldr. For mode == index,
+        // try to encode it as |add scratch, base, imm; ldr dest, [scratch, +offset]|.
+        // This does not wark for mode == PreIndex or mode == PostIndex.
+        // PreIndex is simple, just do the add into the base register first,
+        // then do a PreIndex'ed load. PostIndexed loads can be tricky.
+        // Normally, doing the load with an index of 0, then doing an add would
+        // work, but if the destination is the PC, you don't get to execute the
+        // instruction after the branch, which will lead to the base register
+        // not being updated correctly. Explicitly handle this case, without
+        // doing anything fancy, then handle all of the other cases.
+
+        // mode == Offset
+        //  add   scratch, base, offset_hi
+        //  ldr   dest, [scratch, +offset_lo]
+        //
+        // mode == PreIndex
+        //  add   base, base, offset_hi
+        //  ldr   dest, [base, +offset_lo]!
+
+        int bottom = off & 0xfff;
+        int neg_bottom = 0x1000 - bottom;
+
+        MOZ_ASSERT(rn != scratch);
+        MOZ_ASSERT(mode != PostIndex);
+
+        // At this point, both off - bottom and off + neg_bottom will be
+        // reasonable-ish quantities.
+        //
+        // Note a neg_bottom of 0x1000 can not be encoded as an immediate
+        // negative offset in the instruction and this occurs when bottom is
+        // zero, so this case is guarded against below.
+        if (off < 0) {
+            Operand2 sub_off = Imm8(-(off - bottom)); // sub_off = bottom - off
+            if (!sub_off.invalid()) {
+                // - sub_off = off - bottom
+                as_sub(scratch, rn, sub_off, LeaveCC, cc);
+                return as_dtr(ls, size, Offset, rt, DTRAddr(scratch, DtrOffImm(bottom)), cc);
+            }
+
+            // sub_off = -neg_bottom - off
+            sub_off = Imm8(-(off + neg_bottom));
+            if (!sub_off.invalid() && bottom != 0) {
+                // Guarded against by: bottom != 0
+                MOZ_ASSERT(neg_bottom < 0x1000);
+                // - sub_off = neg_bottom + off
+                as_sub(scratch, rn, sub_off, LeaveCC, cc);
+                return as_dtr(ls, size, Offset, rt, DTRAddr(scratch, DtrOffImm(-neg_bottom)), cc);
+            }
+        } else {
+            // sub_off = off - bottom
+            Operand2 sub_off = Imm8(off - bottom);
+            if (!sub_off.invalid()) {
+                //  sub_off = off - bottom
+                as_add(scratch, rn, sub_off, LeaveCC, cc);
+                return as_dtr(ls, size, Offset, rt, DTRAddr(scratch, DtrOffImm(bottom)), cc);
+            }
+
+            // sub_off = neg_bottom + off
+            sub_off = Imm8(off + neg_bottom);
+            if (!sub_off.invalid() && bottom != 0) {
+                // Guarded against by: bottom != 0
+                MOZ_ASSERT(neg_bottom < 0x1000);
+                // sub_off = neg_bottom + off
+                as_add(scratch, rn, sub_off, LeaveCC,  cc);
+                return as_dtr(ls, size, Offset, rt, DTRAddr(scratch, DtrOffImm(-neg_bottom)), cc);
+            }
+        }
+
+        ma_mov(offset, scratch);
+        return as_dtr(ls, size, mode, rt, DTRAddr(rn, DtrRegImmShift(scratch, LSL, 0)));
+    } else {
+        // Should attempt to use the extended load/store instructions.
+        if (off < 256 && off > -256)
+            return as_extdtr(ls, size, IsSigned, mode, rt, EDtrAddr(rn, EDtrOffImm(off)), cc);
+
+        // We cannot encode this offset in a single extldr. Try to encode it as
+        // an add scratch, base, imm; extldr dest, [scratch, +offset].
+        int bottom = off & 0xff;
+        int neg_bottom = 0x100 - bottom;
+        // At this point, both off - bottom and off + neg_bottom will be
+        // reasonable-ish quantities.
+        //
+        // Note a neg_bottom of 0x100 can not be encoded as an immediate
+        // negative offset in the instruction and this occurs when bottom is
+        // zero, so this case is guarded against below.
+        if (off < 0) {
+            // sub_off = bottom - off
+            Operand2 sub_off = Imm8(-(off - bottom));
+            if (!sub_off.invalid()) {
+                // - sub_off = off - bottom
+                as_sub(scratch, rn, sub_off, LeaveCC, cc);
+                return as_extdtr(ls, size, IsSigned, Offset, rt,
+                                 EDtrAddr(scratch, EDtrOffImm(bottom)),
+                                 cc);
+            }
+            // sub_off = -neg_bottom - off
+            sub_off = Imm8(-(off + neg_bottom));
+            if (!sub_off.invalid() && bottom != 0) {
+                // Guarded against by: bottom != 0
+                MOZ_ASSERT(neg_bottom < 0x100);
+                // - sub_off = neg_bottom + off
+                as_sub(scratch, rn, sub_off, LeaveCC, cc);
+                return as_extdtr(ls, size, IsSigned, Offset, rt,
+                                 EDtrAddr(scratch, EDtrOffImm(-neg_bottom)),
+                                 cc);
+            }
+        } else {
+            // sub_off = off - bottom
+            Operand2 sub_off = Imm8(off - bottom);
+            if (!sub_off.invalid()) {
+                // sub_off = off - bottom
+                as_add(scratch, rn, sub_off, LeaveCC, cc);
+                return as_extdtr(ls, size, IsSigned, Offset, rt,
+                                 EDtrAddr(scratch, EDtrOffImm(bottom)),
+                                 cc);
+            }
+            // sub_off = neg_bottom + off
+            sub_off = Imm8(off + neg_bottom);
+            if (!sub_off.invalid() && bottom != 0) {
+                // Guarded against by: bottom != 0
+                MOZ_ASSERT(neg_bottom < 0x100);
+                // sub_off = neg_bottom + off
+                as_add(scratch, rn, sub_off, LeaveCC,  cc);
+                return as_extdtr(ls, size, IsSigned, Offset, rt,
+                                 EDtrAddr(scratch, EDtrOffImm(-neg_bottom)),
+                                 cc);
+            }
+        }
+        ma_mov(offset, scratch);
+        return as_extdtr(ls, size, IsSigned, mode, rt, EDtrAddr(rn, EDtrOffReg(scratch)), cc);
+    }
+}
+
+void
+MacroAssemblerARM::ma_pop(Register r)
+{
+    as_dtr(IsLoad, 32, PostIndex, r, DTRAddr(sp, DtrOffImm(4)));
+}
+
+void
+MacroAssemblerARM::ma_popn_pc(Imm32 n, AutoRegisterScope& scratch, AutoRegisterScope& scratch2)
+{
+    // pc <- [sp]; sp += n
+    int32_t nv = n.value;
+
+    if (nv < 4096 && nv >= -4096) {
+        as_dtr(IsLoad, 32, PostIndex, pc, DTRAddr(sp, DtrOffImm(nv)));
+    } else {
+        ma_mov(sp, scratch);
+        ma_add(Imm32(n), sp, scratch2);
+        as_dtr(IsLoad, 32, Offset, pc, DTRAddr(scratch, DtrOffImm(0)));
+    }
+}
+
+void
+MacroAssemblerARM::ma_push(Register r)
+{
+    MOZ_ASSERT(r != sp, "Use ma_push_sp().");
+    as_dtr(IsStore, 32, PreIndex, r, DTRAddr(sp, DtrOffImm(-4)));
+}
+
+void
+MacroAssemblerARM::ma_push_sp(Register r, AutoRegisterScope& scratch)
+{
+    // Pushing sp is not well-defined: use two instructions.
+    MOZ_ASSERT(r == sp);
+    ma_mov(sp, scratch);
+    as_dtr(IsStore, 32, PreIndex, scratch, DTRAddr(sp, DtrOffImm(-4)));
+}
+
+void
+MacroAssemblerARM::ma_vpop(VFPRegister r)
+{
+    startFloatTransferM(IsLoad, sp, IA, WriteBack);
+    transferFloatReg(r);
+    finishFloatTransfer();
+}
+
+void
+MacroAssemblerARM::ma_vpush(VFPRegister r)
+{
+    startFloatTransferM(IsStore, sp, DB, WriteBack);
+    transferFloatReg(r);
+    finishFloatTransfer();
+}
+
+// Barriers
+void
+MacroAssemblerARM::ma_dmb(BarrierOption option)
+{
+    if (HasDMBDSBISB())
+        as_dmb(option);
+    else
+        as_dmb_trap();
+}
+
+void
+MacroAssemblerARM::ma_dsb(BarrierOption option)
+{
+    if (HasDMBDSBISB())
+        as_dsb(option);
+    else
+        as_dsb_trap();
+}
+
+// Branches when done from within arm-specific code.
+BufferOffset
+MacroAssemblerARM::ma_b(Label* dest, Assembler::Condition c)
+{
+    return as_b(dest, c);
+}
+
+BufferOffset
+MacroAssemblerARM::ma_b(wasm::TrapDesc target, Assembler::Condition c)
+{
+    return as_b(target, c);
+}
+
+void
+MacroAssemblerARM::ma_bx(Register dest, Assembler::Condition c)
+{
+    as_bx(dest, c);
+}
+
+void
+MacroAssemblerARM::ma_b(void* target, Assembler::Condition c)
+{
+    // An immediate pool is used for easier patching.
+    as_Imm32Pool(pc, uint32_t(target), c);
+}
+
+// This is almost NEVER necessary: we'll basically never be calling a label,
+// except possibly in the crazy bailout-table case.
+void
+MacroAssemblerARM::ma_bl(Label* dest, Assembler::Condition c)
+{
+    as_bl(dest, c);
+}
+
+void
+MacroAssemblerARM::ma_blx(Register reg, Assembler::Condition c)
+{
+    as_blx(reg, c);
+}
+
+// VFP/ALU
+void
+MacroAssemblerARM::ma_vadd(FloatRegister src1, FloatRegister src2, FloatRegister dst)
+{
+    as_vadd(VFPRegister(dst), VFPRegister(src1), VFPRegister(src2));
+}
+
+void
+MacroAssemblerARM::ma_vadd_f32(FloatRegister src1, FloatRegister src2, FloatRegister dst)
+{
+    as_vadd(VFPRegister(dst).singleOverlay(), VFPRegister(src1).singleOverlay(),
+            VFPRegister(src2).singleOverlay());
+}
+
+void
+MacroAssemblerARM::ma_vsub(FloatRegister src1, FloatRegister src2, FloatRegister dst)
+{
+    as_vsub(VFPRegister(dst), VFPRegister(src1), VFPRegister(src2));
+}
+
+void
+MacroAssemblerARM::ma_vsub_f32(FloatRegister src1, FloatRegister src2, FloatRegister dst)
+{
+    as_vsub(VFPRegister(dst).singleOverlay(), VFPRegister(src1).singleOverlay(),
+            VFPRegister(src2).singleOverlay());
+}
+
+void
+MacroAssemblerARM::ma_vmul(FloatRegister src1, FloatRegister src2, FloatRegister dst)
+{
+    as_vmul(VFPRegister(dst), VFPRegister(src1), VFPRegister(src2));
+}
+
+void
+MacroAssemblerARM::ma_vmul_f32(FloatRegister src1, FloatRegister src2, FloatRegister dst)
+{
+    as_vmul(VFPRegister(dst).singleOverlay(), VFPRegister(src1).singleOverlay(),
+            VFPRegister(src2).singleOverlay());
+}
+
+void
+MacroAssemblerARM::ma_vdiv(FloatRegister src1, FloatRegister src2, FloatRegister dst)
+{
+    as_vdiv(VFPRegister(dst), VFPRegister(src1), VFPRegister(src2));
+}
+
+void
+MacroAssemblerARM::ma_vdiv_f32(FloatRegister src1, FloatRegister src2, FloatRegister dst)
+{
+    as_vdiv(VFPRegister(dst).singleOverlay(), VFPRegister(src1).singleOverlay(),
+            VFPRegister(src2).singleOverlay());
+}
+
+void
+MacroAssemblerARM::ma_vmov(FloatRegister src, FloatRegister dest, Condition cc)
+{
+    as_vmov(dest, src, cc);
+}
+
+void
+MacroAssemblerARM::ma_vmov_f32(FloatRegister src, FloatRegister dest, Condition cc)
+{
+    as_vmov(VFPRegister(dest).singleOverlay(), VFPRegister(src).singleOverlay(), cc);
+}
+
+void
+MacroAssemblerARM::ma_vneg(FloatRegister src, FloatRegister dest, Condition cc)
+{
+    as_vneg(dest, src, cc);
+}
+
+void
+MacroAssemblerARM::ma_vneg_f32(FloatRegister src, FloatRegister dest, Condition cc)
+{
+    as_vneg(VFPRegister(dest).singleOverlay(), VFPRegister(src).singleOverlay(), cc);
+}
+
+void
+MacroAssemblerARM::ma_vabs(FloatRegister src, FloatRegister dest, Condition cc)
+{
+    as_vabs(dest, src, cc);
+}
+
+void
+MacroAssemblerARM::ma_vabs_f32(FloatRegister src, FloatRegister dest, Condition cc)
+{
+    as_vabs(VFPRegister(dest).singleOverlay(), VFPRegister(src).singleOverlay(), cc);
+}
+
+void
+MacroAssemblerARM::ma_vsqrt(FloatRegister src, FloatRegister dest, Condition cc)
+{
+    as_vsqrt(dest, src, cc);
+}
+
+void
+MacroAssemblerARM::ma_vsqrt_f32(FloatRegister src, FloatRegister dest, Condition cc)
+{
+    as_vsqrt(VFPRegister(dest).singleOverlay(), VFPRegister(src).singleOverlay(), cc);
+}
+
+static inline uint32_t
+DoubleHighWord(wasm::RawF64 value)
+{
+    return static_cast<uint32_t>(value.bits() >> 32);
+}
+
+static inline uint32_t
+DoubleLowWord(wasm::RawF64 value)
+{
+    return value.bits() & uint32_t(0xffffffff);
+}
+
+void
+MacroAssemblerARM::ma_vimm(wasm::RawF64 value, FloatRegister dest, Condition cc)
+{
+    if (HasVFPv3()) {
+        if (DoubleLowWord(value) == 0) {
+            if (DoubleHighWord(value) == 0) {
+                // To zero a register, load 1.0, then execute dN <- dN - dN
+                as_vimm(dest, VFPImm::One, cc);
+                as_vsub(dest, dest, dest, cc);
+                return;
+            }
+
+            VFPImm enc(DoubleHighWord(value));
+            if (enc.isValid()) {
+                as_vimm(dest, enc, cc);
+                return;
+            }
+        }
+    }
+    // Fall back to putting the value in a pool.
+    as_FImm64Pool(dest, value, cc);
+}
+
+void
+MacroAssemblerARM::ma_vimm_f32(wasm::RawF32 value, FloatRegister dest, Condition cc)
+{
+    VFPRegister vd = VFPRegister(dest).singleOverlay();
+    if (HasVFPv3()) {
+        if (value.bits() == 0) {
+            // To zero a register, load 1.0, then execute sN <- sN - sN.
+            as_vimm(vd, VFPImm::One, cc);
+            as_vsub(vd, vd, vd, cc);
+            return;
+        }
+
+        // Note that the vimm immediate float32 instruction encoding differs
+        // from the vimm immediate double encoding, but this difference matches
+        // the difference in the floating point formats, so it is possible to
+        // convert the float32 to a double and then use the double encoding
+        // paths. It is still necessary to firstly check that the double low
+        // word is zero because some float32 numbers set these bits and this can
+        // not be ignored.
+        wasm::RawF64 doubleValue(double(value.fp()));
+        if (DoubleLowWord(doubleValue) == 0) {
+            VFPImm enc(DoubleHighWord(doubleValue));
+            if (enc.isValid()) {
+                as_vimm(vd, enc, cc);
+                return;
+            }
+        }
+    }
+
+    // Fall back to putting the value in a pool.
+    as_FImm32Pool(vd, value, cc);
+}
+
+void
+MacroAssemblerARM::ma_vcmp(FloatRegister src1, FloatRegister src2, Condition cc)
+{
+    as_vcmp(VFPRegister(src1), VFPRegister(src2), cc);
+}
+
+void
+MacroAssemblerARM::ma_vcmp_f32(FloatRegister src1, FloatRegister src2, Condition cc)
+{
+    as_vcmp(VFPRegister(src1).singleOverlay(), VFPRegister(src2).singleOverlay(), cc);
+}
+
+void
+MacroAssemblerARM::ma_vcmpz(FloatRegister src1, Condition cc)
+{
+    as_vcmpz(VFPRegister(src1), cc);
+}
+
+void
+MacroAssemblerARM::ma_vcmpz_f32(FloatRegister src1, Condition cc)
+{
+    as_vcmpz(VFPRegister(src1).singleOverlay(), cc);
+}
+
+void
+MacroAssemblerARM::ma_vcvt_F64_I32(FloatRegister src, FloatRegister dest, Condition cc)
+{
+    MOZ_ASSERT(src.isDouble());
+    MOZ_ASSERT(dest.isSInt());
+    as_vcvt(dest, src, false, cc);
+}
+
+void
+MacroAssemblerARM::ma_vcvt_F64_U32(FloatRegister src, FloatRegister dest, Condition cc)
+{
+    MOZ_ASSERT(src.isDouble());
+    MOZ_ASSERT(dest.isUInt());
+    as_vcvt(dest, src, false, cc);
+}
+
+void
+MacroAssemblerARM::ma_vcvt_I32_F64(FloatRegister src, FloatRegister dest, Condition cc)
+{
+    MOZ_ASSERT(src.isSInt());
+    MOZ_ASSERT(dest.isDouble());
+    as_vcvt(dest, src, false, cc);
+}
+
+void
+MacroAssemblerARM::ma_vcvt_U32_F64(FloatRegister src, FloatRegister dest, Condition cc)
+{
+    MOZ_ASSERT(src.isUInt());
+    MOZ_ASSERT(dest.isDouble());
+    as_vcvt(dest, src, false, cc);
+}
+
+void
+MacroAssemblerARM::ma_vcvt_F32_I32(FloatRegister src, FloatRegister dest, Condition cc)
+{
+    MOZ_ASSERT(src.isSingle());
+    MOZ_ASSERT(dest.isSInt());
+    as_vcvt(VFPRegister(dest).sintOverlay(), VFPRegister(src).singleOverlay(), false, cc);
+}
+
+void
+MacroAssemblerARM::ma_vcvt_F32_U32(FloatRegister src, FloatRegister dest, Condition cc)
+{
+    MOZ_ASSERT(src.isSingle());
+    MOZ_ASSERT(dest.isUInt());
+    as_vcvt(VFPRegister(dest).uintOverlay(), VFPRegister(src).singleOverlay(), false, cc);
+}
+
+void
+MacroAssemblerARM::ma_vcvt_I32_F32(FloatRegister src, FloatRegister dest, Condition cc)
+{
+    MOZ_ASSERT(src.isSInt());
+    MOZ_ASSERT(dest.isSingle());
+    as_vcvt(VFPRegister(dest).singleOverlay(), VFPRegister(src).sintOverlay(), false, cc);
+}
+
+void
+MacroAssemblerARM::ma_vcvt_U32_F32(FloatRegister src, FloatRegister dest, Condition cc)
+{
+    MOZ_ASSERT(src.isUInt());
+    MOZ_ASSERT(dest.isSingle());
+    as_vcvt(VFPRegister(dest).singleOverlay(), VFPRegister(src).uintOverlay(), false, cc);
+}
+
+void
+MacroAssemblerARM::ma_vxfer(FloatRegister src, Register dest, Condition cc)
+{
+    as_vxfer(dest, InvalidReg, VFPRegister(src).singleOverlay(), FloatToCore, cc);
+}
+
+void
+MacroAssemblerARM::ma_vxfer(FloatRegister src, Register dest1, Register dest2, Condition cc)
+{
+    as_vxfer(dest1, dest2, VFPRegister(src), FloatToCore, cc);
+}
+
+void
+MacroAssemblerARM::ma_vxfer(Register src, FloatRegister dest, Condition cc)
+{
+    as_vxfer(src, InvalidReg, VFPRegister(dest).singleOverlay(), CoreToFloat, cc);
+}
+
+void
+MacroAssemblerARM::ma_vxfer(Register src1, Register src2, FloatRegister dest, Condition cc)
+{
+    as_vxfer(src1, src2, VFPRegister(dest), CoreToFloat, cc);
+}
+
+BufferOffset
+MacroAssemblerARM::ma_vdtr(LoadStore ls, const Address& addr, VFPRegister rt,
+                           AutoRegisterScope& scratch, Condition cc)
+{
+    int off = addr.offset;
+    MOZ_ASSERT((off & 3) == 0);
+    Register base = addr.base;
+    if (off > -1024 && off < 1024)
+        return as_vdtr(ls, rt, Operand(addr).toVFPAddr(), cc);
+
+    // We cannot encode this offset in a a single ldr. Try to encode it as an
+    // add scratch, base, imm; ldr dest, [scratch, +offset].
+    int bottom = off & (0xff << 2);
+    int neg_bottom = (0x100 << 2) - bottom;
+    // At this point, both off - bottom and off + neg_bottom will be
+    // reasonable-ish quantities.
+    //
+    // Note a neg_bottom of 0x400 can not be encoded as an immediate negative
+    // offset in the instruction and this occurs when bottom is zero, so this
+    // case is guarded against below.
+    if (off < 0) {
+        // sub_off = bottom - off
+        Operand2 sub_off = Imm8(-(off - bottom));
+        if (!sub_off.invalid()) {
+            // - sub_off = off - bottom
+            as_sub(scratch, base, sub_off, LeaveCC, cc);
+            return as_vdtr(ls, rt, VFPAddr(scratch, VFPOffImm(bottom)), cc);
+        }
+        // sub_off = -neg_bottom - off
+        sub_off = Imm8(-(off + neg_bottom));
+        if (!sub_off.invalid() && bottom != 0) {
+            // Guarded against by: bottom != 0
+            MOZ_ASSERT(neg_bottom < 0x400);
+            // - sub_off = neg_bottom + off
+            as_sub(scratch, base, sub_off, LeaveCC, cc);
+            return as_vdtr(ls, rt, VFPAddr(scratch, VFPOffImm(-neg_bottom)), cc);
+        }
+    } else {
+        // sub_off = off - bottom
+        Operand2 sub_off = Imm8(off - bottom);
+        if (!sub_off.invalid()) {
+            // sub_off = off - bottom
+            as_add(scratch, base, sub_off, LeaveCC, cc);
+            return as_vdtr(ls, rt, VFPAddr(scratch, VFPOffImm(bottom)), cc);
+        }
+        // sub_off = neg_bottom + off
+        sub_off = Imm8(off + neg_bottom);
+        if (!sub_off.invalid() && bottom != 0) {
+            // Guarded against by: bottom != 0
+            MOZ_ASSERT(neg_bottom < 0x400);
+            // sub_off = neg_bottom + off
+            as_add(scratch, base, sub_off, LeaveCC, cc);
+            return as_vdtr(ls, rt, VFPAddr(scratch, VFPOffImm(-neg_bottom)), cc);
+        }
+    }
+
+    // Safe to use scratch as dest, since ma_add() overwrites dest at the end
+    // and can't use it as internal scratch since it may also == base.
+    ma_add(base, Imm32(off), scratch, scratch, LeaveCC, cc);
+    return as_vdtr(ls, rt, VFPAddr(scratch, VFPOffImm(0)), cc);
+}
+
+BufferOffset
+MacroAssemblerARM::ma_vldr(VFPAddr addr, VFPRegister dest, Condition cc)
+{
+    return as_vdtr(IsLoad, dest, addr, cc);
+}
+
+BufferOffset
+MacroAssemblerARM::ma_vldr(const Address& addr, VFPRegister dest, AutoRegisterScope& scratch, Condition cc)
+{
+    return ma_vdtr(IsLoad, addr, dest, scratch, cc);
+}
+
+BufferOffset
+MacroAssemblerARM::ma_vldr(VFPRegister src, Register base, Register index, AutoRegisterScope& scratch,
+                           int32_t shift, Condition cc)
+{
+    as_add(scratch, base, lsl(index, shift), LeaveCC, cc);
+    return as_vdtr(IsLoad, src, Operand(Address(scratch, 0)).toVFPAddr(), cc);
+}
+
+BufferOffset
+MacroAssemblerARM::ma_vstr(VFPRegister src, VFPAddr addr, Condition cc)
+{
+    return as_vdtr(IsStore, src, addr, cc);
+}
+
+BufferOffset
+MacroAssemblerARM::ma_vstr(VFPRegister src, const Address& addr, AutoRegisterScope& scratch, Condition cc)
+{
+    return ma_vdtr(IsStore, addr, src, scratch, cc);
+}
+
+BufferOffset
+MacroAssemblerARM::ma_vstr(VFPRegister src, Register base, Register index, AutoRegisterScope& scratch,
+                           AutoRegisterScope& scratch2, int32_t shift, int32_t offset, Condition cc)
+{
+    as_add(scratch, base, lsl(index, shift), LeaveCC, cc);
+    return ma_vstr(src, Address(scratch, offset), scratch2, cc);
+}
+
+// Without an offset, no second scratch register is necessary.
+BufferOffset
+MacroAssemblerARM::ma_vstr(VFPRegister src, Register base, Register index, AutoRegisterScope& scratch,
+                           int32_t shift, Condition cc)
+{
+    as_add(scratch, base, lsl(index, shift), LeaveCC, cc);
+    return as_vdtr(IsStore, src, Operand(Address(scratch, 0)).toVFPAddr(), cc);
+}
+
+bool
+MacroAssemblerARMCompat::buildOOLFakeExitFrame(void* fakeReturnAddr)
+{
+    DebugOnly<uint32_t> initialDepth = asMasm().framePushed();
+    uint32_t descriptor = MakeFrameDescriptor(asMasm().framePushed(), JitFrame_IonJS,
+                                              ExitFrameLayout::Size());
+
+    asMasm().Push(Imm32(descriptor)); // descriptor_
+    asMasm().Push(ImmPtr(fakeReturnAddr));
+
+    return true;
+}
+
+void
+MacroAssembler::alignFrameForICArguments(AfterICSaveLive& aic)
+{
+    // Exists for MIPS compatibility.
+}
+
+void
+MacroAssembler::restoreFrameAlignmentForICArguments(AfterICSaveLive& aic)
+{
+    // Exists for MIPS compatibility.
+}
+
+void
+MacroAssemblerARMCompat::move32(Imm32 imm, Register dest)
+{
+    ma_mov(imm, dest);
+}
+
+void
+MacroAssemblerARMCompat::move32(Register src, Register dest)
+{
+    ma_mov(src, dest);
+}
+
+void
+MacroAssemblerARMCompat::movePtr(Register src, Register dest)
+{
+    ma_mov(src, dest);
+}
+
+void
+MacroAssemblerARMCompat::movePtr(ImmWord imm, Register dest)
+{
+    ma_mov(Imm32(imm.value), dest);
+}
+
+void
+MacroAssemblerARMCompat::movePtr(ImmGCPtr imm, Register dest)
+{
+    ma_mov(imm, dest);
+}
+
+void
+MacroAssemblerARMCompat::movePtr(ImmPtr imm, Register dest)
+{
+    movePtr(ImmWord(uintptr_t(imm.value)), dest);
+}
+
+void
+MacroAssemblerARMCompat::movePtr(wasm::SymbolicAddress imm, Register dest)
+{
+    append(wasm::SymbolicAccess(CodeOffset(currentOffset()), imm));
+    ma_movPatchable(Imm32(-1), dest, Always);
+}
+
+void
+MacroAssemblerARMCompat::load8ZeroExtend(const Address& address, Register dest)
+{
+    ScratchRegisterScope scratch(asMasm());
+    ma_dataTransferN(IsLoad, 8, false, address.base, Imm32(address.offset), dest, scratch);
+}
+
+void
+MacroAssemblerARMCompat::load8ZeroExtend(const BaseIndex& src, Register dest)
+{
+    Register base = src.base;
+    uint32_t scale = Imm32::ShiftOf(src.scale).value;
+
+    ScratchRegisterScope scratch(asMasm());
+    SecondScratchRegisterScope scratch2(asMasm());
+
+    if (src.offset == 0) {
+        ma_ldrb(DTRAddr(base, DtrRegImmShift(src.index, LSL, scale)), dest);
+    } else {
+        ma_add(base, Imm32(src.offset), scratch, scratch2);
+        ma_ldrb(DTRAddr(scratch, DtrRegImmShift(src.index, LSL, scale)), dest);
+    }
+}
+
+void
+MacroAssemblerARMCompat::load8SignExtend(const Address& address, Register dest)
+{
+    ScratchRegisterScope scratch(asMasm());
+    ma_dataTransferN(IsLoad, 8, true, address.base, Imm32(address.offset), dest, scratch);
+}
+
+void
+MacroAssemblerARMCompat::load8SignExtend(const BaseIndex& src, Register dest)
+{
+    Register index = src.index;
+
+    ScratchRegisterScope scratch(asMasm());
+    SecondScratchRegisterScope scratch2(asMasm());
+
+    // ARMv7 does not have LSL on an index register with an extended load.
+    if (src.scale != TimesOne) {
+        ma_lsl(Imm32::ShiftOf(src.scale), index, scratch);
+        index = scratch;
+    }
+
+    if (src.offset != 0) {
+        if (index != scratch) {
+            ma_mov(index, scratch);
+            index = scratch;
+        }
+        ma_add(Imm32(src.offset), index, scratch2);
+    }
+    ma_ldrsb(EDtrAddr(src.base, EDtrOffReg(index)), dest);
+}
+
+void
+MacroAssemblerARMCompat::load16ZeroExtend(const Address& address, Register dest)
+{
+    ScratchRegisterScope scratch(asMasm());
+    ma_dataTransferN(IsLoad, 16, false, address.base, Imm32(address.offset), dest, scratch);
+}
+
+void
+MacroAssemblerARMCompat::load16ZeroExtend(const BaseIndex& src, Register dest)
+{
+    Register index = src.index;
+
+    ScratchRegisterScope scratch(asMasm());
+    SecondScratchRegisterScope scratch2(asMasm());
+
+    // ARMv7 does not have LSL on an index register with an extended load.
+    if (src.scale != TimesOne) {
+        ma_lsl(Imm32::ShiftOf(src.scale), index, scratch);
+        index = scratch;
+    }
+
+    if (src.offset != 0) {
+        if (index != scratch) {
+            ma_mov(index, scratch);
+            index = scratch;
+        }
+        ma_add(Imm32(src.offset), index, scratch2);
+    }
+    ma_ldrh(EDtrAddr(src.base, EDtrOffReg(index)), dest);
+}
+
+void
+MacroAssemblerARMCompat::load16SignExtend(const Address& address, Register dest)
+{
+    ScratchRegisterScope scratch(asMasm());
+    ma_dataTransferN(IsLoad, 16, true, address.base, Imm32(address.offset), dest, scratch);
+}
+
+void
+MacroAssemblerARMCompat::load16SignExtend(const BaseIndex& src, Register dest)
+{
+    Register index = src.index;
+
+    ScratchRegisterScope scratch(asMasm());
+    SecondScratchRegisterScope scratch2(asMasm());
+
+    // We don't have LSL on index register yet.
+    if (src.scale != TimesOne) {
+        ma_lsl(Imm32::ShiftOf(src.scale), index, scratch);
+        index = scratch;
+    }
+
+    if (src.offset != 0) {
+        if (index != scratch) {
+            ma_mov(index, scratch);
+            index = scratch;
+        }
+        ma_add(Imm32(src.offset), index, scratch2);
+    }
+    ma_ldrsh(EDtrAddr(src.base, EDtrOffReg(index)), dest);
+}
+
+void
+MacroAssemblerARMCompat::load32(const Address& address, Register dest)
+{
+    loadPtr(address, dest);
+}
+
+void
+MacroAssemblerARMCompat::load32(const BaseIndex& address, Register dest)
+{
+    loadPtr(address, dest);
+}
+
+void
+MacroAssemblerARMCompat::load32(AbsoluteAddress address, Register dest)
+{
+    loadPtr(address, dest);
+}
+
+void
+MacroAssemblerARMCompat::loadPtr(const Address& address, Register dest)
+{
+    ScratchRegisterScope scratch(asMasm());
+    ma_ldr(address, dest, scratch);
+}
+
+void
+MacroAssemblerARMCompat::loadPtr(const BaseIndex& src, Register dest)
+{
+    Register base = src.base;
+    uint32_t scale = Imm32::ShiftOf(src.scale).value;
+
+    ScratchRegisterScope scratch(asMasm());
+    SecondScratchRegisterScope scratch2(asMasm());
+
+    if (src.offset != 0) {
+        ma_add(base, Imm32(src.offset), scratch, scratch2);
+        ma_ldr(DTRAddr(scratch, DtrRegImmShift(src.index, LSL, scale)), dest);
+    } else {
+        ma_ldr(DTRAddr(base, DtrRegImmShift(src.index, LSL, scale)), dest);
+    }
+}
+
+void
+MacroAssemblerARMCompat::loadPtr(AbsoluteAddress address, Register dest)
+{
+    MOZ_ASSERT(dest != pc); // Use dest as a scratch register.
+    movePtr(ImmWord(uintptr_t(address.addr)), dest);
+    loadPtr(Address(dest, 0), dest);
+}
+
+void
+MacroAssemblerARMCompat::loadPtr(wasm::SymbolicAddress address, Register dest)
+{
+    MOZ_ASSERT(dest != pc); // Use dest as a scratch register.
+    movePtr(address, dest);
+    loadPtr(Address(dest, 0), dest);
+}
+
+void
+MacroAssemblerARMCompat::loadPrivate(const Address& address, Register dest)
+{
+    ScratchRegisterScope scratch(asMasm());
+    ma_ldr(ToPayload(address), dest, scratch);
+}
+
+void
+MacroAssemblerARMCompat::loadDouble(const Address& address, FloatRegister dest)
+{
+    ScratchRegisterScope scratch(asMasm());
+    ma_vldr(address, dest, scratch);
+}
+
+void
+MacroAssemblerARMCompat::loadDouble(const BaseIndex& src, FloatRegister dest)
+{
+    // VFP instructions don't even support register Base + register Index modes,
+    // so just add the index, then handle the offset like normal.
+    Register base = src.base;
+    Register index = src.index;
+    uint32_t scale = Imm32::ShiftOf(src.scale).value;
+    int32_t offset = src.offset;
+
+    ScratchRegisterScope scratch(asMasm());
+    SecondScratchRegisterScope scratch2(asMasm());
+
+    as_add(scratch, base, lsl(index, scale));
+    ma_vldr(Address(scratch, offset), dest, scratch2);
+}
+
+void
+MacroAssemblerARMCompat::loadFloatAsDouble(const Address& address, FloatRegister dest)
+{
+    ScratchRegisterScope scratch(asMasm());
+
+    VFPRegister rt = dest;
+    ma_vldr(address, rt.singleOverlay(), scratch);
+    as_vcvt(rt, rt.singleOverlay());
+}
+
+void
+MacroAssemblerARMCompat::loadFloatAsDouble(const BaseIndex& src, FloatRegister dest)
+{
+    // VFP instructions don't even support register Base + register Index modes,
+    // so just add the index, then handle the offset like normal.
+    Register base = src.base;
+    Register index = src.index;
+    uint32_t scale = Imm32::ShiftOf(src.scale).value;
+    int32_t offset = src.offset;
+    VFPRegister rt = dest;
+
+    ScratchRegisterScope scratch(asMasm());
+    SecondScratchRegisterScope scratch2(asMasm());
+
+    as_add(scratch, base, lsl(index, scale));
+    ma_vldr(Address(scratch, offset), rt.singleOverlay(), scratch2);
+    as_vcvt(rt, rt.singleOverlay());
+}
+
+void
+MacroAssemblerARMCompat::loadFloat32(const Address& address, FloatRegister dest)
+{
+    ScratchRegisterScope scratch(asMasm());
+    ma_vldr(address, VFPRegister(dest).singleOverlay(), scratch);
+}
+
+void
+MacroAssemblerARMCompat::loadFloat32(const BaseIndex& src, FloatRegister dest)
+{
+    // VFP instructions don't even support register Base + register Index modes,
+    // so just add the index, then handle the offset like normal.
+    Register base = src.base;
+    Register index = src.index;
+    uint32_t scale = Imm32::ShiftOf(src.scale).value;
+    int32_t offset = src.offset;
+
+    ScratchRegisterScope scratch(asMasm());
+    SecondScratchRegisterScope scratch2(asMasm());
+
+    as_add(scratch, base, lsl(index, scale));
+    ma_vldr(Address(scratch, offset), VFPRegister(dest).singleOverlay(), scratch2);
+}
+
+void
+MacroAssemblerARMCompat::store8(Imm32 imm, const Address& address)
+{
+    SecondScratchRegisterScope scratch2(asMasm());
+    ma_mov(imm, scratch2);
+    store8(scratch2, address);
+}
+
+void
+MacroAssemblerARMCompat::store8(Register src, const Address& address)
+{
+    ScratchRegisterScope scratch(asMasm());
+    ma_dataTransferN(IsStore, 8, false, address.base, Imm32(address.offset), src, scratch);
+}
+
+void
+MacroAssemblerARMCompat::store8(Imm32 imm, const BaseIndex& dest)
+{
+    Register base = dest.base;
+    uint32_t scale = Imm32::ShiftOf(dest.scale).value;
+
+    ScratchRegisterScope scratch(asMasm());
+    SecondScratchRegisterScope scratch2(asMasm());
+
+    if (dest.offset != 0) {
+        ma_add(base, Imm32(dest.offset), scratch, scratch2);
+        ma_mov(imm, scratch2);
+        ma_strb(scratch2, DTRAddr(scratch, DtrRegImmShift(dest.index, LSL, scale)));
+    } else {
+        ma_mov(imm, scratch2);
+        ma_strb(scratch2, DTRAddr(base, DtrRegImmShift(dest.index, LSL, scale)));
+    }
+}
+
+void
+MacroAssemblerARMCompat::store8(Register src, const BaseIndex& dest)
+{
+    Register base = dest.base;
+    uint32_t scale = Imm32::ShiftOf(dest.scale).value;
+
+    ScratchRegisterScope scratch(asMasm());
+    SecondScratchRegisterScope scratch2(asMasm());
+
+    if (dest.offset != 0) {
+        ma_add(base, Imm32(dest.offset), scratch, scratch2);
+        ma_strb(src, DTRAddr(scratch, DtrRegImmShift(dest.index, LSL, scale)));
+    } else {
+        ma_strb(src, DTRAddr(base, DtrRegImmShift(dest.index, LSL, scale)));
+    }
+}
+
+void
+MacroAssemblerARMCompat::store16(Imm32 imm, const Address& address)
+{
+    SecondScratchRegisterScope scratch2(asMasm());
+    ma_mov(imm, scratch2);
+    store16(scratch2, address);
+}
+
+void
+MacroAssemblerARMCompat::store16(Register src, const Address& address)
+{
+    ScratchRegisterScope scratch(asMasm());
+    ma_dataTransferN(IsStore, 16, false, address.base, Imm32(address.offset), src, scratch);
+}
+
+void
+MacroAssemblerARMCompat::store16(Imm32 imm, const BaseIndex& dest)
+{
+    Register index = dest.index;
+
+    ScratchRegisterScope scratch(asMasm());
+    SecondScratchRegisterScope scratch2(asMasm());
+
+    // We don't have LSL on index register yet.
+    if (dest.scale != TimesOne) {
+        ma_lsl(Imm32::ShiftOf(dest.scale), index, scratch);
+        index = scratch;
+    }
+
+    if (dest.offset != 0) {
+        ma_add(index, Imm32(dest.offset), scratch, scratch2);
+        index = scratch;
+    }
+
+    ma_mov(imm, scratch2);
+    ma_strh(scratch2, EDtrAddr(dest.base, EDtrOffReg(index)));
+}
+
+void
+MacroAssemblerARMCompat::store16(Register src, const BaseIndex& address)
+{
+    Register index = address.index;
+
+    ScratchRegisterScope scratch(asMasm());
+    SecondScratchRegisterScope scratch2(asMasm());
+
+    // We don't have LSL on index register yet.
+    if (address.scale != TimesOne) {
+        ma_lsl(Imm32::ShiftOf(address.scale), index, scratch);
+        index = scratch;
+    }
+
+    if (address.offset != 0) {
+        ma_add(index, Imm32(address.offset), scratch, scratch2);
+        index = scratch;
+    }
+    ma_strh(src, EDtrAddr(address.base, EDtrOffReg(index)));
+}
+
+void
+MacroAssemblerARMCompat::store32(Register src, AbsoluteAddress address)
+{
+    storePtr(src, address);
+}
+
+void
+MacroAssemblerARMCompat::store32(Register src, const Address& address)
+{
+    storePtr(src, address);
+}
+
+void
+MacroAssemblerARMCompat::store32(Imm32 src, const Address& address)
+{
+    ScratchRegisterScope scratch(asMasm());
+    SecondScratchRegisterScope scratch2(asMasm());
+    move32(src, scratch);
+    ma_str(scratch, address, scratch2);
+}
+
+void
+MacroAssemblerARMCompat::store32(Imm32 imm, const BaseIndex& dest)
+{
+    Register base = dest.base;
+    uint32_t scale = Imm32::ShiftOf(dest.scale).value;
+
+    ScratchRegisterScope scratch(asMasm());
+    SecondScratchRegisterScope scratch2(asMasm());
+
+    if (dest.offset != 0) {
+        ma_add(base, Imm32(dest.offset), scratch, scratch2);
+        ma_mov(imm, scratch2);
+        ma_str(scratch2, DTRAddr(scratch, DtrRegImmShift(dest.index, LSL, scale)));
+    } else {
+        ma_mov(imm, scratch);
+        ma_str(scratch, DTRAddr(base, DtrRegImmShift(dest.index, LSL, scale)));
+    }
+
+}
+
+void
+MacroAssemblerARMCompat::store32(Register src, const BaseIndex& dest)
+{
+    Register base = dest.base;
+    uint32_t scale = Imm32::ShiftOf(dest.scale).value;
+
+    ScratchRegisterScope scratch(asMasm());
+    SecondScratchRegisterScope scratch2(asMasm());
+
+    if (dest.offset != 0) {
+        ma_add(base, Imm32(dest.offset), scratch, scratch2);
+        ma_str(src, DTRAddr(scratch, DtrRegImmShift(dest.index, LSL, scale)));
+    } else {
+        ma_str(src, DTRAddr(base, DtrRegImmShift(dest.index, LSL, scale)));
+    }
+}
+
+void
+MacroAssemblerARMCompat::storePtr(ImmWord imm, const Address& address)
+{
+    store32(Imm32(imm.value), address);
+}
+
+void
+MacroAssemblerARMCompat::storePtr(ImmWord imm, const BaseIndex& address)
+{
+    store32(Imm32(imm.value), address);
+}
+
+void
+MacroAssemblerARMCompat::storePtr(ImmPtr imm, const Address& address)
+{
+    store32(Imm32(uintptr_t(imm.value)), address);
+}
+
+void
+MacroAssemblerARMCompat::storePtr(ImmPtr imm, const BaseIndex& address)
+{
+    store32(Imm32(uintptr_t(imm.value)), address);
+}
+
+void
+MacroAssemblerARMCompat::storePtr(ImmGCPtr imm, const Address& address)
+{
+    ScratchRegisterScope scratch(asMasm());
+    SecondScratchRegisterScope scratch2(asMasm());
+    ma_mov(imm, scratch);
+    ma_str(scratch, address, scratch2);
+}
+
+void
+MacroAssemblerARMCompat::storePtr(ImmGCPtr imm, const BaseIndex& address)
+{
+    Register base = address.base;
+    uint32_t scale = Imm32::ShiftOf(address.scale).value;
+
+    ScratchRegisterScope scratch(asMasm());
+    SecondScratchRegisterScope scratch2(asMasm());
+
+    if (address.offset != 0) {
+        ma_add(base, Imm32(address.offset), scratch, scratch2);
+        ma_mov(imm, scratch2);
+        ma_str(scratch2, DTRAddr(scratch, DtrRegImmShift(address.index, LSL, scale)));
+    } else {
+        ma_mov(imm, scratch);
+        ma_str(scratch, DTRAddr(base, DtrRegImmShift(address.index, LSL, scale)));
+    }
+}
+
+void
+MacroAssemblerARMCompat::storePtr(Register src, const Address& address)
+{
+    SecondScratchRegisterScope scratch2(asMasm());
+    ma_str(src, address, scratch2);
+}
+
+void
+MacroAssemblerARMCompat::storePtr(Register src, const BaseIndex& address)
+{
+    store32(src, address);
+}
+
+void
+MacroAssemblerARMCompat::storePtr(Register src, AbsoluteAddress dest)
+{
+    ScratchRegisterScope scratch(asMasm());
+    movePtr(ImmWord(uintptr_t(dest.addr)), scratch);
+    ma_str(src, DTRAddr(scratch, DtrOffImm(0)));
+}
+
+// Note: this function clobbers the input register.
+void
+MacroAssembler::clampDoubleToUint8(FloatRegister input, Register output)
+{
+    if (HasVFPv3()) {
+        Label notSplit;
+        {
+            ScratchDoubleScope scratchDouble(*this);
+            MOZ_ASSERT(input != scratchDouble);
+            loadConstantDouble(0.5, scratchDouble);
+
+            ma_vadd(input, scratchDouble, scratchDouble);
+            // Convert the double into an unsigned fixed point value with 24 bits of
+            // precision. The resulting number will look like 0xII.DDDDDD
+            as_vcvtFixed(scratchDouble, false, 24, true);
+        }
+
+        // Move the fixed point value into an integer register.
+        {
+            ScratchFloat32Scope scratchFloat(*this);
+            as_vxfer(output, InvalidReg, scratchFloat.uintOverlay(), FloatToCore);
+        }
+
+        ScratchRegisterScope scratch(*this);
+
+        // See if this value *might* have been an exact integer after adding
+        // 0.5. This tests the 1/2 through 1/16,777,216th places, but 0.5 needs
+        // to be tested out to the 1/140,737,488,355,328th place.
+        ma_tst(output, Imm32(0x00ffffff), scratch);
+        // Convert to a uint8 by shifting out all of the fraction bits.
+        ma_lsr(Imm32(24), output, output);
+        // If any of the bottom 24 bits were non-zero, then we're good, since
+        // this number can't be exactly XX.0
+        ma_b(&notSplit, NonZero);
+        as_vxfer(scratch, InvalidReg, input, FloatToCore);
+        as_cmp(scratch, Imm8(0));
+        // If the lower 32 bits of the double were 0, then this was an exact number,
+        // and it should be even.
+        as_bic(output, output, Imm8(1), LeaveCC, Zero);
+        bind(&notSplit);
+    } else {
+        ScratchDoubleScope scratchDouble(*this);
+        MOZ_ASSERT(input != scratchDouble);
+        loadConstantDouble(0.5, scratchDouble);
+
+        Label outOfRange;
+        ma_vcmpz(input);
+        // Do the add, in place so we can reference it later.
+        ma_vadd(input, scratchDouble, input);
+        // Do the conversion to an integer.
+        as_vcvt(VFPRegister(scratchDouble).uintOverlay(), VFPRegister(input));
+        // Copy the converted value out.
+        as_vxfer(output, InvalidReg, scratchDouble, FloatToCore);
+        as_vmrs(pc);
+        ma_mov(Imm32(0), output, Overflow);  // NaN => 0
+        ma_b(&outOfRange, Overflow);  // NaN
+        as_cmp(output, Imm8(0xff));
+        ma_mov(Imm32(0xff), output, Above);
+        ma_b(&outOfRange, Above);
+        // Convert it back to see if we got the same value back.
+        as_vcvt(scratchDouble, VFPRegister(scratchDouble).uintOverlay());
+        // Do the check.
+        as_vcmp(scratchDouble, input);
+        as_vmrs(pc);
+        as_bic(output, output, Imm8(1), LeaveCC, Zero);
+        bind(&outOfRange);
+    }
+}
+
+void
+MacroAssemblerARMCompat::cmp32(Register lhs, Imm32 rhs)
+{
+    ScratchRegisterScope scratch(asMasm());
+    ma_cmp(lhs, rhs, scratch);
+}
+
+void
+MacroAssemblerARMCompat::cmp32(Register lhs, Register rhs)
+{
+    ma_cmp(lhs, rhs);
+}
+
+void
+MacroAssemblerARMCompat::cmpPtr(Register lhs, ImmWord rhs)
+{
+    cmp32(lhs, Imm32(rhs.value));
+}
+
+void
+MacroAssemblerARMCompat::cmpPtr(Register lhs, ImmPtr rhs)
+{
+    cmpPtr(lhs, ImmWord(uintptr_t(rhs.value)));
+}
+
+void
+MacroAssemblerARMCompat::cmpPtr(Register lhs, Register rhs)
+{
+    ma_cmp(lhs, rhs);
+}
+
+void
+MacroAssemblerARMCompat::cmpPtr(Register lhs, ImmGCPtr rhs)
+{
+    ScratchRegisterScope scratch(asMasm());
+    ma_cmp(lhs, rhs, scratch);
+}
+
+void
+MacroAssemblerARMCompat::cmpPtr(Register lhs, Imm32 rhs)
+{
+    cmp32(lhs, rhs);
+}
+
+void
+MacroAssemblerARMCompat::cmpPtr(const Address& lhs, Register rhs)
+{
+    ScratchRegisterScope scratch(asMasm());
+    SecondScratchRegisterScope scratch2(asMasm());
+    ma_ldr(lhs, scratch, scratch2);
+    ma_cmp(scratch, rhs);
+}
+
+void
+MacroAssemblerARMCompat::cmpPtr(const Address& lhs, ImmWord rhs)
+{
+    ScratchRegisterScope scratch(asMasm());
+    SecondScratchRegisterScope scratch2(asMasm());
+    ma_ldr(lhs, scratch, scratch2);
+    ma_cmp(scratch, Imm32(rhs.value), scratch2);
+}
+
+void
+MacroAssemblerARMCompat::cmpPtr(const Address& lhs, ImmPtr rhs)
+{
+    cmpPtr(lhs, ImmWord(uintptr_t(rhs.value)));
+}
+
+void
+MacroAssemblerARMCompat::cmpPtr(const Address& lhs, ImmGCPtr rhs)
+{
+    ScratchRegisterScope scratch(asMasm());
+    SecondScratchRegisterScope scratch2(asMasm());
+    ma_ldr(lhs, scratch, scratch2);
+    ma_cmp(scratch, rhs, scratch2);
+}
+
+void
+MacroAssemblerARMCompat::cmpPtr(const Address& lhs, Imm32 rhs)
+{
+    ScratchRegisterScope scratch(asMasm());
+    SecondScratchRegisterScope scratch2(asMasm());
+    ma_ldr(lhs, scratch, scratch2);
+    ma_cmp(scratch, rhs, scratch2);
+}
+
+void
+MacroAssemblerARMCompat::setStackArg(Register reg, uint32_t arg)
+{
+    ScratchRegisterScope scratch(asMasm());
+    ma_dataTransferN(IsStore, 32, true, sp, Imm32(arg * sizeof(intptr_t)), reg, scratch);
+}
+
+void
+MacroAssemblerARMCompat::minMaxDouble(FloatRegister srcDest, FloatRegister second, bool canBeNaN,
+                                      bool isMax)
+{
+    FloatRegister first = srcDest;
+
+    Label nan, equal, returnSecond, done;
+
+    Assembler::Condition cond = isMax
+                                ? Assembler::VFP_LessThanOrEqual
+                                : Assembler::VFP_GreaterThanOrEqual;
+
+    compareDouble(first, second);
+    // First or second is NaN, result is NaN.
+    ma_b(&nan, Assembler::VFP_Unordered);
+    // Make sure we handle -0 and 0 right.
+    ma_b(&equal, Assembler::VFP_Equal);
+    ma_b(&returnSecond, cond);
+    ma_b(&done);
+
+    // Check for zero.
+    bind(&equal);
+    compareDouble(first, NoVFPRegister);
+    // First wasn't 0 or -0, so just return it.
+    ma_b(&done, Assembler::VFP_NotEqualOrUnordered);
+    // So now both operands are either -0 or 0.
+    if (isMax) {
+        // -0 + -0 = -0 and -0 + 0 = 0.
+        ma_vadd(second, first, first);
+    } else {
+        ma_vneg(first, first);
+        ma_vsub(first, second, first);
+        ma_vneg(first, first);
+    }
+    ma_b(&done);
+
+    bind(&nan);
+    // If the first argument is the NaN, return it; otherwise return the second
+    // operand.
+    compareDouble(first, first);
+    ma_vmov(first, srcDest, Assembler::VFP_Unordered);
+    ma_b(&done, Assembler::VFP_Unordered);
+
+    bind(&returnSecond);
+    ma_vmov(second, srcDest);
+
+    bind(&done);
+}
+
+void
+MacroAssemblerARMCompat::minMaxFloat32(FloatRegister srcDest, FloatRegister second, bool canBeNaN,
+                                       bool isMax)
+{
+    FloatRegister first = srcDest;
+
+    Label nan, equal, returnSecond, done;
+
+    Assembler::Condition cond = isMax
+                                ? Assembler::VFP_LessThanOrEqual
+                                : Assembler::VFP_GreaterThanOrEqual;
+
+    compareFloat(first, second);
+    // First or second is NaN, result is NaN.
+    ma_b(&nan, Assembler::VFP_Unordered);
+    // Make sure we handle -0 and 0 right.
+    ma_b(&equal, Assembler::VFP_Equal);
+    ma_b(&returnSecond, cond);
+    ma_b(&done);
+
+    // Check for zero.
+    bind(&equal);
+    compareFloat(first, NoVFPRegister);
+    // First wasn't 0 or -0, so just return it.
+    ma_b(&done, Assembler::VFP_NotEqualOrUnordered);
+    // So now both operands are either -0 or 0.
+    if (isMax) {
+        // -0 + -0 = -0 and -0 + 0 = 0.
+        ma_vadd_f32(second, first, first);
+    } else {
+        ma_vneg_f32(first, first);
+        ma_vsub_f32(first, second, first);
+        ma_vneg_f32(first, first);
+    }
+    ma_b(&done);
+
+    bind(&nan);
+    // See comment in minMaxDouble.
+    compareFloat(first, first);
+    ma_vmov_f32(first, srcDest, Assembler::VFP_Unordered);
+    ma_b(&done, Assembler::VFP_Unordered);
+
+    bind(&returnSecond);
+    ma_vmov_f32(second, srcDest);
+
+    bind(&done);
+}
+
+void
+MacroAssemblerARMCompat::compareDouble(FloatRegister lhs, FloatRegister rhs)
+{
+    // Compare the doubles, setting vector status flags.
+    if (rhs.isMissing())
+        ma_vcmpz(lhs);
+    else
+        ma_vcmp(lhs, rhs);
+
+    // Move vector status bits to normal status flags.
+    as_vmrs(pc);
+}
+
+void
+MacroAssemblerARMCompat::compareFloat(FloatRegister lhs, FloatRegister rhs)
+{
+    // Compare the doubles, setting vector status flags.
+    if (rhs.isMissing())
+        as_vcmpz(VFPRegister(lhs).singleOverlay());
+    else
+        as_vcmp(VFPRegister(lhs).singleOverlay(), VFPRegister(rhs).singleOverlay());
+
+    // Move vector status bits to normal status flags.
+    as_vmrs(pc);
+}
+
+Assembler::Condition
+MacroAssemblerARMCompat::testInt32(Assembler::Condition cond, const ValueOperand& value)
+{
+    MOZ_ASSERT(cond == Assembler::Equal || cond == Assembler::NotEqual);
+    ma_cmp(value.typeReg(), ImmType(JSVAL_TYPE_INT32));
+    return cond;
+}
+
+Assembler::Condition
+MacroAssemblerARMCompat::testBoolean(Assembler::Condition cond, const ValueOperand& value)
+{
+    MOZ_ASSERT(cond == Assembler::Equal || cond == Assembler::NotEqual);
+    ma_cmp(value.typeReg(), ImmType(JSVAL_TYPE_BOOLEAN));
+    return cond;
+}
+
+Assembler::Condition
+MacroAssemblerARMCompat::testDouble(Assembler::Condition cond, const ValueOperand& value)
+{
+    MOZ_ASSERT(cond == Assembler::Equal || cond == Assembler::NotEqual);
+    Assembler::Condition actual = (cond == Equal) ? Below : AboveOrEqual;
+    ScratchRegisterScope scratch(asMasm());
+    ma_cmp(value.typeReg(), ImmTag(JSVAL_TAG_CLEAR), scratch);
+    return actual;
+}
+
+Assembler::Condition
+MacroAssemblerARMCompat::testNull(Assembler::Condition cond, const ValueOperand& value)
+{
+    MOZ_ASSERT(cond == Assembler::Equal || cond == Assembler::NotEqual);
+    ma_cmp(value.typeReg(), ImmType(JSVAL_TYPE_NULL));
+    return cond;
+}
+
+Assembler::Condition
+MacroAssemblerARMCompat::testUndefined(Assembler::Condition cond, const ValueOperand& value)
+{
+    MOZ_ASSERT(cond == Assembler::Equal || cond == Assembler::NotEqual);
+    ma_cmp(value.typeReg(), ImmType(JSVAL_TYPE_UNDEFINED));
+    return cond;
+}
+
+Assembler::Condition
+MacroAssemblerARMCompat::testString(Assembler::Condition cond, const ValueOperand& value)
+{
+    return testString(cond, value.typeReg());
+}
+
+Assembler::Condition
+MacroAssemblerARMCompat::testSymbol(Assembler::Condition cond, const ValueOperand& value)
+{
+    return testSymbol(cond, value.typeReg());
+}
+
+Assembler::Condition
+MacroAssemblerARMCompat::testObject(Assembler::Condition cond, const ValueOperand& value)
+{
+    return testObject(cond, value.typeReg());
+}
+
+Assembler::Condition
+MacroAssemblerARMCompat::testNumber(Assembler::Condition cond, const ValueOperand& value)
+{
+    return testNumber(cond, value.typeReg());
+}
+
+Assembler::Condition
+MacroAssemblerARMCompat::testMagic(Assembler::Condition cond, const ValueOperand& value)
+{
+    return testMagic(cond, value.typeReg());
+}
+
+Assembler::Condition
+MacroAssemblerARMCompat::testPrimitive(Assembler::Condition cond, const ValueOperand& value)
+{
+    return testPrimitive(cond, value.typeReg());
+}
+
+// Register-based tests.
+Assembler::Condition
+MacroAssemblerARMCompat::testInt32(Assembler::Condition cond, Register tag)
+{
+    MOZ_ASSERT(cond == Equal || cond == NotEqual);
+    ma_cmp(tag, ImmTag(JSVAL_TAG_INT32));
+    return cond;
+}
+
+Assembler::Condition
+MacroAssemblerARMCompat::testBoolean(Assembler::Condition cond, Register tag)
+{
+    MOZ_ASSERT(cond == Equal || cond == NotEqual);
+    ma_cmp(tag, ImmTag(JSVAL_TAG_BOOLEAN));
+    return cond;
+}
+
+Assembler::Condition
+MacroAssemblerARMCompat::testNull(Assembler::Condition cond, Register tag)
+{
+    MOZ_ASSERT(cond == Equal || cond == NotEqual);
+    ma_cmp(tag, ImmTag(JSVAL_TAG_NULL));
+    return cond;
+}
+
+Assembler::Condition
+MacroAssemblerARMCompat::testUndefined(Assembler::Condition cond, Register tag)
+{
+    MOZ_ASSERT(cond == Equal || cond == NotEqual);
+    ma_cmp(tag, ImmTag(JSVAL_TAG_UNDEFINED));
+    return cond;
+}
+
+Assembler::Condition
+MacroAssemblerARMCompat::testString(Assembler::Condition cond, Register tag)
+{
+    MOZ_ASSERT(cond == Equal || cond == NotEqual);
+    ma_cmp(tag, ImmTag(JSVAL_TAG_STRING));
+    return cond;
+}
+
+Assembler::Condition
+MacroAssemblerARMCompat::testSymbol(Assembler::Condition cond, Register tag)
+{
+    MOZ_ASSERT(cond == Equal || cond == NotEqual);
+    ma_cmp(tag, ImmTag(JSVAL_TAG_SYMBOL));
+    return cond;
+}
+
+Assembler::Condition
+MacroAssemblerARMCompat::testObject(Assembler::Condition cond, Register tag)
+{
+    MOZ_ASSERT(cond == Equal || cond == NotEqual);
+    ma_cmp(tag, ImmTag(JSVAL_TAG_OBJECT));
+    return cond;
+}
+
+Assembler::Condition
+MacroAssemblerARMCompat::testMagic(Assembler::Condition cond, Register tag)
+{
+    MOZ_ASSERT(cond == Equal || cond == NotEqual);
+    ma_cmp(tag, ImmTag(JSVAL_TAG_MAGIC));
+    return cond;
+}
+
+Assembler::Condition
+MacroAssemblerARMCompat::testPrimitive(Assembler::Condition cond, Register tag)
+{
+    MOZ_ASSERT(cond == Equal || cond == NotEqual);
+    ma_cmp(tag, ImmTag(JSVAL_UPPER_EXCL_TAG_OF_PRIMITIVE_SET));
+    return cond == Equal ? Below : AboveOrEqual;
+}
+
+Assembler::Condition
+MacroAssemblerARMCompat::testGCThing(Assembler::Condition cond, const Address& address)
+{
+    MOZ_ASSERT(cond == Equal || cond == NotEqual);
+    ScratchRegisterScope scratch(asMasm());
+    extractTag(address, scratch);
+    ma_cmp(scratch, ImmTag(JSVAL_LOWER_INCL_TAG_OF_GCTHING_SET));
+    return cond == Equal ? AboveOrEqual : Below;
+}
+
+Assembler::Condition
+MacroAssemblerARMCompat::testMagic(Assembler::Condition cond, const Address& address)
+{
+    MOZ_ASSERT(cond == Equal || cond == NotEqual);
+    ScratchRegisterScope scratch(asMasm());
+    extractTag(address, scratch);
+    ma_cmp(scratch, ImmTag(JSVAL_TAG_MAGIC));
+    return cond;
+}
+
+Assembler::Condition
+MacroAssemblerARMCompat::testInt32(Assembler::Condition cond, const Address& address)
+{
+    MOZ_ASSERT(cond == Equal || cond == NotEqual);
+    ScratchRegisterScope scratch(asMasm());
+    extractTag(address, scratch);
+    ma_cmp(scratch, ImmTag(JSVAL_TAG_INT32));
+    return cond;
+}
+
+Assembler::Condition
+MacroAssemblerARMCompat::testDouble(Condition cond, const Address& address)
+{
+    MOZ_ASSERT(cond == Equal || cond == NotEqual);
+    ScratchRegisterScope scratch(asMasm());
+    extractTag(address, scratch);
+    return testDouble(cond, scratch);
+}
+
+Assembler::Condition
+MacroAssemblerARMCompat::testBoolean(Condition cond, const Address& address)
+{
+    MOZ_ASSERT(cond == Equal || cond == NotEqual);
+    ScratchRegisterScope scratch(asMasm());
+    extractTag(address, scratch);
+    return testBoolean(cond, scratch);
+}
+
+Assembler::Condition
+MacroAssemblerARMCompat::testNull(Condition cond, const Address& address)
+{
+    MOZ_ASSERT(cond == Equal || cond == NotEqual);
+    ScratchRegisterScope scratch(asMasm());
+    extractTag(address, scratch);
+    return testNull(cond, scratch);
+}
+
+Assembler::Condition
+MacroAssemblerARMCompat::testUndefined(Condition cond, const Address& address)
+{
+    MOZ_ASSERT(cond == Equal || cond == NotEqual);
+    ScratchRegisterScope scratch(asMasm());
+    extractTag(address, scratch);
+    return testUndefined(cond, scratch);
+}
+
+Assembler::Condition
+MacroAssemblerARMCompat::testString(Condition cond, const Address& address)
+{
+    MOZ_ASSERT(cond == Equal || cond == NotEqual);
+    ScratchRegisterScope scratch(asMasm());
+    extractTag(address, scratch);
+    return testString(cond, scratch);
+}
+
+Assembler::Condition
+MacroAssemblerARMCompat::testSymbol(Condition cond, const Address& address)
+{
+    MOZ_ASSERT(cond == Equal || cond == NotEqual);
+    ScratchRegisterScope scratch(asMasm());
+    extractTag(address, scratch);
+    return testSymbol(cond, scratch);
+}
+
+Assembler::Condition
+MacroAssemblerARMCompat::testObject(Condition cond, const Address& address)
+{
+    MOZ_ASSERT(cond == Equal || cond == NotEqual);
+    ScratchRegisterScope scratch(asMasm());
+    extractTag(address, scratch);
+    return testObject(cond, scratch);
+}
+
+Assembler::Condition
+MacroAssemblerARMCompat::testNumber(Condition cond, const Address& address)
+{
+    MOZ_ASSERT(cond == Equal || cond == NotEqual);
+    ScratchRegisterScope scratch(asMasm());
+    extractTag(address, scratch);
+    return testNumber(cond, scratch);
+}
+
+Assembler::Condition
+MacroAssemblerARMCompat::testDouble(Condition cond, Register tag)
+{
+    MOZ_ASSERT(cond == Assembler::Equal || cond == Assembler::NotEqual);
+    Condition actual = (cond == Equal) ? Below : AboveOrEqual;
+    ma_cmp(tag, ImmTag(JSVAL_TAG_CLEAR));
+    return actual;
+}
+
+Assembler::Condition
+MacroAssemblerARMCompat::testNumber(Condition cond, Register tag)
+{
+    MOZ_ASSERT(cond == Equal || cond == NotEqual);
+    ma_cmp(tag, ImmTag(JSVAL_UPPER_INCL_TAG_OF_NUMBER_SET));
+    return cond == Equal ? BelowOrEqual : Above;
+}
+
+Assembler::Condition
+MacroAssemblerARMCompat::testUndefined(Condition cond, const BaseIndex& src)
+{
+    MOZ_ASSERT(cond == Equal || cond == NotEqual);
+    ScratchRegisterScope scratch(asMasm());
+    extractTag(src, scratch);
+    ma_cmp(scratch, ImmTag(JSVAL_TAG_UNDEFINED));
+    return cond;
+}
+
+Assembler::Condition
+MacroAssemblerARMCompat::testNull(Condition cond, const BaseIndex& src)
+{
+    MOZ_ASSERT(cond == Equal || cond == NotEqual);
+    ScratchRegisterScope scratch(asMasm());
+    extractTag(src, scratch);
+    ma_cmp(scratch, ImmTag(JSVAL_TAG_NULL));
+    return cond;
+}
+
+Assembler::Condition
+MacroAssemblerARMCompat::testBoolean(Condition cond, const BaseIndex& src)
+{
+    MOZ_ASSERT(cond == Equal || cond == NotEqual);
+    ScratchRegisterScope scratch(asMasm());
+    extractTag(src, scratch);
+    ma_cmp(scratch, ImmTag(JSVAL_TAG_BOOLEAN));
+    return cond;
+}
+
+Assembler::Condition
+MacroAssemblerARMCompat::testString(Condition cond, const BaseIndex& src)
+{
+    MOZ_ASSERT(cond == Equal || cond == NotEqual);
+    ScratchRegisterScope scratch(asMasm());
+    extractTag(src, scratch);
+    ma_cmp(scratch, ImmTag(JSVAL_TAG_STRING));
+    return cond;
+}
+
+Assembler::Condition
+MacroAssemblerARMCompat::testSymbol(Condition cond, const BaseIndex& src)
+{
+    MOZ_ASSERT(cond == Equal || cond == NotEqual);
+    ScratchRegisterScope scratch(asMasm());
+    extractTag(src, scratch);
+    ma_cmp(scratch, ImmTag(JSVAL_TAG_SYMBOL));
+    return cond;
+}
+
+Assembler::Condition
+MacroAssemblerARMCompat::testInt32(Condition cond, const BaseIndex& src)
+{
+    MOZ_ASSERT(cond == Equal || cond == NotEqual);
+    ScratchRegisterScope scratch(asMasm());
+    extractTag(src, scratch);
+    ma_cmp(scratch, ImmTag(JSVAL_TAG_INT32));
+    return cond;
+}
+
+Assembler::Condition
+MacroAssemblerARMCompat::testObject(Condition cond, const BaseIndex& src)
+{
+    MOZ_ASSERT(cond == Equal || cond == NotEqual);
+    ScratchRegisterScope scratch(asMasm());
+    extractTag(src, scratch);
+    ma_cmp(scratch, ImmTag(JSVAL_TAG_OBJECT));
+    return cond;
+}
+
+Assembler::Condition
+MacroAssemblerARMCompat::testDouble(Condition cond, const BaseIndex& src)
+{
+    MOZ_ASSERT(cond == Equal || cond == NotEqual);
+    Assembler::Condition actual = (cond == Equal) ? Below : AboveOrEqual;
+    ScratchRegisterScope scratch(asMasm());
+    extractTag(src, scratch);
+    ma_cmp(scratch, ImmTag(JSVAL_TAG_CLEAR));
+    return actual;
+}
+
+Assembler::Condition
+MacroAssemblerARMCompat::testMagic(Condition cond, const BaseIndex& address)
+{
+    MOZ_ASSERT(cond == Equal || cond == NotEqual);
+    ScratchRegisterScope scratch(asMasm());
+    extractTag(address, scratch);
+    ma_cmp(scratch, ImmTag(JSVAL_TAG_MAGIC));
+    return cond;
+}
+
+Assembler::Condition
+MacroAssemblerARMCompat::testGCThing(Condition cond, const BaseIndex& address)
+{
+    MOZ_ASSERT(cond == Equal || cond == NotEqual);
+    ScratchRegisterScope scratch(asMasm());
+    extractTag(address, scratch);
+    ma_cmp(scratch, ImmTag(JSVAL_LOWER_INCL_TAG_OF_GCTHING_SET));
+    return cond == Equal ? AboveOrEqual : Below;
+}
+
+// Unboxing code.
+void
+MacroAssemblerARMCompat::unboxNonDouble(const ValueOperand& operand, Register dest)
+{
+    if (operand.payloadReg() != dest)
+        ma_mov(operand.payloadReg(), dest);
+}
+
+void
+MacroAssemblerARMCompat::unboxNonDouble(const Address& src, Register dest)
+{
+    ScratchRegisterScope scratch(asMasm());
+    ma_ldr(ToPayload(src), dest, scratch);
+}
+
+void
+MacroAssemblerARMCompat::unboxNonDouble(const BaseIndex& src, Register dest)
+{
+    ScratchRegisterScope scratch(asMasm());
+    SecondScratchRegisterScope scratch2(asMasm());
+    ma_alu(src.base, lsl(src.index, src.scale), scratch, OpAdd);
+    ma_ldr(Address(scratch, src.offset), dest, scratch2);
+}
+
+void
+MacroAssemblerARMCompat::unboxDouble(const ValueOperand& operand, FloatRegister dest)
+{
+    MOZ_ASSERT(dest.isDouble());
+    as_vxfer(operand.payloadReg(), operand.typeReg(),
+             VFPRegister(dest), CoreToFloat);
+}
+
+void
+MacroAssemblerARMCompat::unboxDouble(const Address& src, FloatRegister dest)
+{
+    MOZ_ASSERT(dest.isDouble());
+    ScratchRegisterScope scratch(asMasm());
+    ma_vldr(src, dest, scratch);
+}
+
+void
+MacroAssemblerARMCompat::unboxValue(const ValueOperand& src, AnyRegister dest)
+{
+    if (dest.isFloat()) {
+        Label notInt32, end;
+        asMasm().branchTestInt32(Assembler::NotEqual, src, &notInt32);
+        convertInt32ToDouble(src.payloadReg(), dest.fpu());
+        ma_b(&end);
+        bind(&notInt32);
+        unboxDouble(src, dest.fpu());
+        bind(&end);
+    } else if (src.payloadReg() != dest.gpr()) {
+        as_mov(dest.gpr(), O2Reg(src.payloadReg()));
+    }
+}
+
+void
+MacroAssemblerARMCompat::unboxPrivate(const ValueOperand& src, Register dest)
+{
+    ma_mov(src.payloadReg(), dest);
+}
+
+void
+MacroAssemblerARMCompat::boxDouble(FloatRegister src, const ValueOperand& dest)
+{
+    as_vxfer(dest.payloadReg(), dest.typeReg(), VFPRegister(src), FloatToCore);
+}
+
+void
+MacroAssemblerARMCompat::boxNonDouble(JSValueType type, Register src, const ValueOperand& dest) {
+    if (src != dest.payloadReg())
+        ma_mov(src, dest.payloadReg());
+    ma_mov(ImmType(type), dest.typeReg());
+}
+
+void
+MacroAssemblerARMCompat::boolValueToDouble(const ValueOperand& operand, FloatRegister dest)
+{
+    VFPRegister d = VFPRegister(dest);
+    loadConstantDouble(1.0, dest);
+    as_cmp(operand.payloadReg(), Imm8(0));
+    // If the source is 0, then subtract the dest from itself, producing 0.
+    as_vsub(d, d, d, Equal);
+}
+
+void
+MacroAssemblerARMCompat::int32ValueToDouble(const ValueOperand& operand, FloatRegister dest)
+{
+    VFPRegister vfpdest = VFPRegister(dest);
+    ScratchFloat32Scope scratch(asMasm());
+
+    // Transfer the integral value to a floating point register.
+    as_vxfer(operand.payloadReg(), InvalidReg, scratch.sintOverlay(), CoreToFloat);
+    // Convert the value to a double.
+    as_vcvt(vfpdest, scratch.sintOverlay());
+}
+
+void
+MacroAssemblerARMCompat::boolValueToFloat32(const ValueOperand& operand, FloatRegister dest)
+{
+    VFPRegister d = VFPRegister(dest).singleOverlay();
+    loadConstantFloat32(1.0, dest);
+    as_cmp(operand.payloadReg(), Imm8(0));
+    // If the source is 0, then subtract the dest from itself, producing 0.
+    as_vsub(d, d, d, Equal);
+}
+
+void
+MacroAssemblerARMCompat::int32ValueToFloat32(const ValueOperand& operand, FloatRegister dest)
+{
+    // Transfer the integral value to a floating point register.
+    VFPRegister vfpdest = VFPRegister(dest).singleOverlay();
+    as_vxfer(operand.payloadReg(), InvalidReg,
+             vfpdest.sintOverlay(), CoreToFloat);
+    // Convert the value to a float.
+    as_vcvt(vfpdest, vfpdest.sintOverlay());
+}
+
+void
+MacroAssemblerARMCompat::loadConstantFloat32(float f, FloatRegister dest)
+{
+    loadConstantFloat32(wasm::RawF32(f), dest);
+}
+
+void
+MacroAssemblerARMCompat::loadConstantFloat32(wasm::RawF32 f, FloatRegister dest)
+{
+    ma_vimm_f32(f, dest);
+}
+
+void
+MacroAssemblerARMCompat::loadInt32OrDouble(const Address& src, FloatRegister dest)
+{
+    Label notInt32, end;
+
+    // If it's an int, convert to a double.
+    {
+        ScratchRegisterScope scratch(asMasm());
+        SecondScratchRegisterScope scratch2(asMasm());
+
+        ma_ldr(ToType(src), scratch, scratch2);
+        asMasm().branchTestInt32(Assembler::NotEqual, scratch, &notInt32);
+        ma_ldr(ToPayload(src), scratch, scratch2);
+        convertInt32ToDouble(scratch, dest);
+        ma_b(&end);
+    }
+
+    // Not an int, just load as double.
+    bind(&notInt32);
+    {
+        ScratchRegisterScope scratch(asMasm());
+        ma_vldr(src, dest, scratch);
+    }
+    bind(&end);
+}
+
+void
+MacroAssemblerARMCompat::loadInt32OrDouble(Register base, Register index,
+                                           FloatRegister dest, int32_t shift)
+{
+    Label notInt32, end;
+
+    JS_STATIC_ASSERT(NUNBOX32_PAYLOAD_OFFSET == 0);
+
+    ScratchRegisterScope scratch(asMasm());
+
+    // If it's an int, convert it to double.
+    ma_alu(base, lsl(index, shift), scratch, OpAdd);
+
+    // Since we only have one scratch register, we need to stomp over it with
+    // the tag.
+    ma_ldr(DTRAddr(scratch, DtrOffImm(NUNBOX32_TYPE_OFFSET)), scratch);
+    asMasm().branchTestInt32(Assembler::NotEqual, scratch, &notInt32);
+
+    // Implicitly requires NUNBOX32_PAYLOAD_OFFSET == 0: no offset provided
+    ma_ldr(DTRAddr(base, DtrRegImmShift(index, LSL, shift)), scratch);
+    convertInt32ToDouble(scratch, dest);
+    ma_b(&end);
+
+    // Not an int, just load as double.
+    bind(&notInt32);
+    // First, recompute the offset that had been stored in the scratch register
+    // since the scratch register was overwritten loading in the type.
+    ma_alu(base, lsl(index, shift), scratch, OpAdd);
+    ma_vldr(VFPAddr(scratch, VFPOffImm(0)), dest);
+    bind(&end);
+}
+
+void
+MacroAssemblerARMCompat::loadConstantDouble(double dp, FloatRegister dest)
+{
+    loadConstantDouble(wasm::RawF64(dp), dest);
+}
+
+void
+MacroAssemblerARMCompat::loadConstantDouble(wasm::RawF64 dp, FloatRegister dest)
+{
+    ma_vimm(dp, dest);
+}
+
+// Treat the value as a boolean, and set condition codes accordingly.
+Assembler::Condition
+MacroAssemblerARMCompat::testInt32Truthy(bool truthy, const ValueOperand& operand)
+{
+    ma_tst(operand.payloadReg(), operand.payloadReg());
+    return truthy ? NonZero : Zero;
+}
+
+Assembler::Condition
+MacroAssemblerARMCompat::testBooleanTruthy(bool truthy, const ValueOperand& operand)
+{
+    ma_tst(operand.payloadReg(), operand.payloadReg());
+    return truthy ? NonZero : Zero;
+}
+
+Assembler::Condition
+MacroAssemblerARMCompat::testDoubleTruthy(bool truthy, FloatRegister reg)
+{
+    as_vcmpz(VFPRegister(reg));
+    as_vmrs(pc);
+    as_cmp(r0, O2Reg(r0), Overflow);
+    return truthy ? NonZero : Zero;
+}
+
+Register
+MacroAssemblerARMCompat::extractObject(const Address& address, Register scratch)
+{
+    SecondScratchRegisterScope scratch2(asMasm());
+    ma_ldr(ToPayload(address), scratch, scratch2);
+    return scratch;
+}
+
+Register
+MacroAssemblerARMCompat::extractTag(const Address& address, Register scratch)
+{
+    SecondScratchRegisterScope scratch2(asMasm());
+    ma_ldr(ToType(address), scratch, scratch2);
+    return scratch;
+}
+
+Register
+MacroAssemblerARMCompat::extractTag(const BaseIndex& address, Register scratch)
+{
+    ma_alu(address.base, lsl(address.index, address.scale), scratch, OpAdd, LeaveCC);
+    return extractTag(Address(scratch, address.offset), scratch);
+}
+
+void
+MacroAssemblerARMCompat::moveValue(const Value& val, Register type, Register data)
+{
+    ma_mov(Imm32(val.toNunboxTag()), type);
+    if (val.isMarkable())
+        ma_mov(ImmGCPtr(val.toMarkablePointer()), data);
+    else
+        ma_mov(Imm32(val.toNunboxPayload()), data);
+}
+
+void
+MacroAssemblerARMCompat::moveValue(const Value& val, const ValueOperand& dest)
+{
+    moveValue(val, dest.typeReg(), dest.payloadReg());
+}
+
+/////////////////////////////////////////////////////////////////
+// X86/X64-common (ARM too now) interface.
+/////////////////////////////////////////////////////////////////
+void
+MacroAssemblerARMCompat::storeValue(ValueOperand val, const Address& dst)
+{
+    SecondScratchRegisterScope scratch2(asMasm());
+    ma_str(val.payloadReg(), ToPayload(dst), scratch2);
+    ma_str(val.typeReg(), ToType(dst), scratch2);
+}
+
+void
+MacroAssemblerARMCompat::storeValue(ValueOperand val, const BaseIndex& dest)
+{
+    ScratchRegisterScope scratch(asMasm());
+
+    if (isValueDTRDCandidate(val) && Abs(dest.offset) <= 255) {
+        Register tmpIdx;
+        if (dest.offset == 0) {
+            if (dest.scale == TimesOne) {
+                tmpIdx = dest.index;
+            } else {
+                ma_lsl(Imm32(dest.scale), dest.index, scratch);
+                tmpIdx = scratch;
+            }
+            ma_strd(val.payloadReg(), val.typeReg(), EDtrAddr(dest.base, EDtrOffReg(tmpIdx)));
+        } else {
+            ma_alu(dest.base, lsl(dest.index, dest.scale), scratch, OpAdd);
+            ma_strd(val.payloadReg(), val.typeReg(),
+                    EDtrAddr(scratch, EDtrOffImm(dest.offset)));
+        }
+    } else {
+        ma_alu(dest.base, lsl(dest.index, dest.scale), scratch, OpAdd);
+        storeValue(val, Address(scratch, dest.offset));
+    }
+}
+
+void
+MacroAssemblerARMCompat::loadValue(const BaseIndex& addr, ValueOperand val)
+{
+    ScratchRegisterScope scratch(asMasm());
+
+    if (isValueDTRDCandidate(val) && Abs(addr.offset) <= 255) {
+        Register tmpIdx;
+        if (addr.offset == 0) {
+            if (addr.scale == TimesOne) {
+                // If the offset register is the same as one of the destination
+                // registers, LDRD's behavior is undefined. Use the scratch
+                // register to avoid this.
+                if (val.aliases(addr.index)) {
+                    ma_mov(addr.index, scratch);
+                    tmpIdx = scratch;
+                } else {
+                    tmpIdx = addr.index;
+                }
+            } else {
+                ma_lsl(Imm32(addr.scale), addr.index, scratch);
+                tmpIdx = scratch;
+            }
+            ma_ldrd(EDtrAddr(addr.base, EDtrOffReg(tmpIdx)), val.payloadReg(), val.typeReg());
+        } else {
+            ma_alu(addr.base, lsl(addr.index, addr.scale), scratch, OpAdd);
+            ma_ldrd(EDtrAddr(scratch, EDtrOffImm(addr.offset)),
+                    val.payloadReg(), val.typeReg());
+        }
+    } else {
+        ma_alu(addr.base, lsl(addr.index, addr.scale), scratch, OpAdd);
+        loadValue(Address(scratch, addr.offset), val);
+    }
+}
+
+void
+MacroAssemblerARMCompat::loadValue(Address src, ValueOperand val)
+{
+    Address payload = ToPayload(src);
+    Address type = ToType(src);
+
+    // TODO: copy this code into a generic function that acts on all sequences
+    // of memory accesses
+    if (isValueDTRDCandidate(val)) {
+        // If the value we want is in two consecutive registers starting with an
+        // even register, they can be combined as a single ldrd.
+        int offset = src.offset;
+        if (offset < 256 && offset > -256) {
+            ma_ldrd(EDtrAddr(src.base, EDtrOffImm(src.offset)), val.payloadReg(), val.typeReg());
+            return;
+        }
+    }
+    // If the value is lower than the type, then we may be able to use an ldm
+    // instruction.
+
+    if (val.payloadReg().code() < val.typeReg().code()) {
+        if (src.offset <= 4 && src.offset >= -8 && (src.offset & 3) == 0) {
+            // Turns out each of the 4 value -8, -4, 0, 4 corresponds exactly
+            // with one of LDM{DB, DA, IA, IB}
+            DTMMode mode;
+            switch (src.offset) {
+              case -8: mode = DB; break;
+              case -4: mode = DA; break;
+              case  0: mode = IA; break;
+              case  4: mode = IB; break;
+              default: MOZ_CRASH("Bogus Offset for LoadValue as DTM");
+            }
+            startDataTransferM(IsLoad, src.base, mode);
+            transferReg(val.payloadReg());
+            transferReg(val.typeReg());
+            finishDataTransfer();
+            return;
+        }
+    }
+    // Ensure that loading the payload does not erase the pointer to the Value
+    // in memory.
+    if (type.base != val.payloadReg()) {
+        SecondScratchRegisterScope scratch2(asMasm());
+        ma_ldr(payload, val.payloadReg(), scratch2);
+        ma_ldr(type, val.typeReg(), scratch2);
+    } else {
+        SecondScratchRegisterScope scratch2(asMasm());
+        ma_ldr(type, val.typeReg(), scratch2);
+        ma_ldr(payload, val.payloadReg(), scratch2);
+    }
+}
+
+void
+MacroAssemblerARMCompat::tagValue(JSValueType type, Register payload, ValueOperand dest)
+{
+    MOZ_ASSERT(dest.typeReg() != dest.payloadReg());
+    if (payload != dest.payloadReg())
+        ma_mov(payload, dest.payloadReg());
+    ma_mov(ImmType(type), dest.typeReg());
+}
+
+void
+MacroAssemblerARMCompat::pushValue(ValueOperand val)
+{
+    ma_push(val.typeReg());
+    ma_push(val.payloadReg());
+}
+
+void
+MacroAssemblerARMCompat::pushValue(const Address& addr)
+{
+    ScratchRegisterScope scratch(asMasm());
+    SecondScratchRegisterScope scratch2(asMasm());
+
+    ma_ldr(ToType(addr), scratch, scratch2);
+    ma_push(scratch);
+    ma_ldr(ToPayloadAfterStackPush(addr), scratch, scratch2);
+    ma_push(scratch);
+}
+
+void
+MacroAssemblerARMCompat::popValue(ValueOperand val)
+{
+    ma_pop(val.payloadReg());
+    ma_pop(val.typeReg());
+}
+
+void
+MacroAssemblerARMCompat::storePayload(const Value& val, const Address& dest)
+{
+    ScratchRegisterScope scratch(asMasm());
+    SecondScratchRegisterScope scratch2(asMasm());
+
+    if (val.isMarkable())
+        ma_mov(ImmGCPtr(val.toMarkablePointer()), scratch);
+    else
+        ma_mov(Imm32(val.toNunboxPayload()), scratch);
+    ma_str(scratch, ToPayload(dest), scratch2);
+}
+
+void
+MacroAssemblerARMCompat::storePayload(Register src, const Address& dest)
+{
+    ScratchRegisterScope scratch(asMasm());
+    ma_str(src, ToPayload(dest), scratch);
+}
+
+void
+MacroAssemblerARMCompat::storePayload(const Value& val, const BaseIndex& dest)
+{
+    unsigned shift = ScaleToShift(dest.scale);
+
+    ScratchRegisterScope scratch(asMasm());
+    SecondScratchRegisterScope scratch2(asMasm());
+
+    if (val.isMarkable())
+        ma_mov(ImmGCPtr(val.toMarkablePointer()), scratch);
+    else
+        ma_mov(Imm32(val.toNunboxPayload()), scratch);
+
+    // If NUNBOX32_PAYLOAD_OFFSET is not zero, the memory operand [base + index
+    // << shift + imm] cannot be encoded into a single instruction, and cannot
+    // be integrated into the as_dtr call.
+    JS_STATIC_ASSERT(NUNBOX32_PAYLOAD_OFFSET == 0);
+
+    // If an offset is used, modify the base so that a [base + index << shift]
+    // instruction format can be used.
+    if (dest.offset != 0)
+        ma_add(dest.base, Imm32(dest.offset), dest.base, scratch2);
+
+    as_dtr(IsStore, 32, Offset, scratch,
+           DTRAddr(dest.base, DtrRegImmShift(dest.index, LSL, shift)));
+
+    // Restore the original value of the base, if necessary.
+    if (dest.offset != 0)
+        ma_sub(dest.base, Imm32(dest.offset), dest.base, scratch);
+}
+
+void
+MacroAssemblerARMCompat::storePayload(Register src, const BaseIndex& dest)
+{
+    unsigned shift = ScaleToShift(dest.scale);
+    MOZ_ASSERT(shift < 32);
+
+    ScratchRegisterScope scratch(asMasm());
+
+    // If NUNBOX32_PAYLOAD_OFFSET is not zero, the memory operand [base + index
+    // << shift + imm] cannot be encoded into a single instruction, and cannot
+    // be integrated into the as_dtr call.
+    JS_STATIC_ASSERT(NUNBOX32_PAYLOAD_OFFSET == 0);
+
+    // Save/restore the base if the BaseIndex has an offset, as above.
+    if (dest.offset != 0)
+        ma_add(dest.base, Imm32(dest.offset), dest.base, scratch);
+
+    // Technically, shift > -32 can be handle by changing LSL to ASR, but should
+    // never come up, and this is one less code path to get wrong.
+    as_dtr(IsStore, 32, Offset, src, DTRAddr(dest.base, DtrRegImmShift(dest.index, LSL, shift)));
+
+    if (dest.offset != 0)
+        ma_sub(dest.base, Imm32(dest.offset), dest.base, scratch);
+}
+
+void
+MacroAssemblerARMCompat::storeTypeTag(ImmTag tag, const Address& dest)
+{
+    ScratchRegisterScope scratch(asMasm());
+    SecondScratchRegisterScope scratch2(asMasm());
+
+    ma_mov(tag, scratch);
+    ma_str(scratch, ToType(dest), scratch2);
+}
+
+void
+MacroAssemblerARMCompat::storeTypeTag(ImmTag tag, const BaseIndex& dest)
+{
+    Register base = dest.base;
+    Register index = dest.index;
+    unsigned shift = ScaleToShift(dest.scale);
+
+    ScratchRegisterScope scratch(asMasm());
+    SecondScratchRegisterScope scratch2(asMasm());
+
+    MOZ_ASSERT(base != scratch && base != scratch2);
+    MOZ_ASSERT(index != scratch && index != scratch2);
+
+    ma_add(base, Imm32(dest.offset + NUNBOX32_TYPE_OFFSET), scratch2, scratch);
+    ma_mov(tag, scratch);
+    ma_str(scratch, DTRAddr(scratch2, DtrRegImmShift(index, LSL, shift)));
+}
+
+void
+MacroAssemblerARM::ma_call(ImmPtr dest)
+{
+    ma_movPatchable(dest, CallReg, Always);
+    as_blx(CallReg);
+}
+
+void
+MacroAssemblerARMCompat::breakpoint()
+{
+    as_bkpt();
+}
+
+void
+MacroAssemblerARMCompat::simulatorStop(const char* msg)
+{
+#ifdef JS_SIMULATOR_ARM
+    MOZ_ASSERT(sizeof(char*) == 4);
+    writeInst(0xefffffff);
+    writeInst((int)msg);
+#endif
+}
+
+void
+MacroAssemblerARMCompat::ensureDouble(const ValueOperand& source, FloatRegister dest, Label* failure)
+{
+    Label isDouble, done;
+    asMasm().branchTestDouble(Assembler::Equal, source.typeReg(), &isDouble);
+    asMasm().branchTestInt32(Assembler::NotEqual, source.typeReg(), failure);
+
+    convertInt32ToDouble(source.payloadReg(), dest);
+    jump(&done);
+
+    bind(&isDouble);
+    unboxDouble(source, dest);
+
+    bind(&done);
+}
+
+void
+MacroAssemblerARMCompat::breakpoint(Condition cc)
+{
+    ma_ldr(DTRAddr(r12, DtrRegImmShift(r12, LSL, 0, IsDown)), r12, Offset, cc);
+}
+
+void
+MacroAssemblerARMCompat::checkStackAlignment()
+{
+    asMasm().assertStackAlignment(ABIStackAlignment);
+}
+
+void
+MacroAssemblerARMCompat::handleFailureWithHandlerTail(void* handler)
+{
+    // Reserve space for exception information.
+    int size = (sizeof(ResumeFromException) + 7) & ~7;
+
+    Imm8 size8(size);
+    as_sub(sp, sp, size8);
+    ma_mov(sp, r0);
+
+    // Call the handler.
+    asMasm().setupUnalignedABICall(r1);
+    asMasm().passABIArg(r0);
+    asMasm().callWithABI(handler);
+
+    Label entryFrame;
+    Label catch_;
+    Label finally;
+    Label return_;
+    Label bailout;
+
+    {
+        ScratchRegisterScope scratch(asMasm());
+        ma_ldr(Address(sp, offsetof(ResumeFromException, kind)), r0, scratch);
+    }
+
+    asMasm().branch32(Assembler::Equal, r0, Imm32(ResumeFromException::RESUME_ENTRY_FRAME),
+                      &entryFrame);
+    asMasm().branch32(Assembler::Equal, r0, Imm32(ResumeFromException::RESUME_CATCH), &catch_);
+    asMasm().branch32(Assembler::Equal, r0, Imm32(ResumeFromException::RESUME_FINALLY), &finally);
+    asMasm().branch32(Assembler::Equal, r0, Imm32(ResumeFromException::RESUME_FORCED_RETURN),
+                      &return_);
+    asMasm().branch32(Assembler::Equal, r0, Imm32(ResumeFromException::RESUME_BAILOUT), &bailout);
+
+    breakpoint(); // Invalid kind.
+
+    // No exception handler. Load the error value, load the new stack pointer
+    // and return from the entry frame.
+    bind(&entryFrame);
+    moveValue(MagicValue(JS_ION_ERROR), JSReturnOperand);
+    {
+        ScratchRegisterScope scratch(asMasm());
+        ma_ldr(Address(sp, offsetof(ResumeFromException, stackPointer)), sp, scratch);
+    }
+
+    // We're going to be returning by the ion calling convention, which returns
+    // by ??? (for now, I think ldr pc, [sp]!)
+    as_dtr(IsLoad, 32, PostIndex, pc, DTRAddr(sp, DtrOffImm(4)));
+
+    // If we found a catch handler, this must be a baseline frame. Restore state
+    // and jump to the catch block.
+    bind(&catch_);
+    {
+        ScratchRegisterScope scratch(asMasm());
+        ma_ldr(Address(sp, offsetof(ResumeFromException, target)), r0, scratch);
+        ma_ldr(Address(sp, offsetof(ResumeFromException, framePointer)), r11, scratch);
+        ma_ldr(Address(sp, offsetof(ResumeFromException, stackPointer)), sp, scratch);
+    }
+    jump(r0);
+
+    // If we found a finally block, this must be a baseline frame. Push two
+    // values expected by JSOP_RETSUB: BooleanValue(true) and the exception.
+    bind(&finally);
+    ValueOperand exception = ValueOperand(r1, r2);
+    loadValue(Operand(sp, offsetof(ResumeFromException, exception)), exception);
+    {
+        ScratchRegisterScope scratch(asMasm());
+        ma_ldr(Address(sp, offsetof(ResumeFromException, target)), r0, scratch);
+        ma_ldr(Address(sp, offsetof(ResumeFromException, framePointer)), r11, scratch);
+        ma_ldr(Address(sp, offsetof(ResumeFromException, stackPointer)), sp, scratch);
+    }
+
+    pushValue(BooleanValue(true));
+    pushValue(exception);
+    jump(r0);
+
+    // Only used in debug mode. Return BaselineFrame->returnValue() to the
+    // caller.
+    bind(&return_);
+    {
+        ScratchRegisterScope scratch(asMasm());
+        ma_ldr(Address(sp, offsetof(ResumeFromException, framePointer)), r11, scratch);
+        ma_ldr(Address(sp, offsetof(ResumeFromException, stackPointer)), sp, scratch);
+    }
+    loadValue(Address(r11, BaselineFrame::reverseOffsetOfReturnValue()), JSReturnOperand);
+    ma_mov(r11, sp);
+    pop(r11);
+
+    // If profiling is enabled, then update the lastProfilingFrame to refer to caller
+    // frame before returning.
+    {
+        Label skipProfilingInstrumentation;
+        // Test if profiler enabled.
+        AbsoluteAddress addressOfEnabled(GetJitContext()->runtime->spsProfiler().addressOfEnabled());
+        asMasm().branch32(Assembler::Equal, addressOfEnabled, Imm32(0),
+                          &skipProfilingInstrumentation);
+        profilerExitFrame();
+        bind(&skipProfilingInstrumentation);
+    }
+
+    ret();
+
+    // If we are bailing out to baseline to handle an exception, jump to the
+    // bailout tail stub.
+    bind(&bailout);
+    {
+        ScratchRegisterScope scratch(asMasm());
+        ma_ldr(Address(sp, offsetof(ResumeFromException, bailoutInfo)), r2, scratch);
+        ma_mov(Imm32(BAILOUT_RETURN_OK), r0);
+        ma_ldr(Address(sp, offsetof(ResumeFromException, target)), r1, scratch);
+    }
+    jump(r1);
+}
+
+Assembler::Condition
+MacroAssemblerARMCompat::testStringTruthy(bool truthy, const ValueOperand& value)
+{
+    Register string = value.payloadReg();
+    ScratchRegisterScope scratch(asMasm());
+    SecondScratchRegisterScope scratch2(asMasm());
+
+    ma_dtr(IsLoad, string, Imm32(JSString::offsetOfLength()), scratch, scratch2);
+    as_cmp(scratch, Imm8(0));
+    return truthy ? Assembler::NotEqual : Assembler::Equal;
+}
+
+void
+MacroAssemblerARMCompat::floor(FloatRegister input, Register output, Label* bail)
+{
+    Label handleZero;
+    Label handleNeg;
+    Label fin;
+
+    ScratchDoubleScope scratchDouble(asMasm());
+
+    compareDouble(input, NoVFPRegister);
+    ma_b(&handleZero, Assembler::Equal);
+    ma_b(&handleNeg, Assembler::Signed);
+    // NaN is always a bail condition, just bail directly.
+    ma_b(bail, Assembler::Overflow);
+
+    // The argument is a positive number, truncation is the path to glory. Since
+    // it is known to be > 0.0, explicitly convert to a larger range, then a
+    // value that rounds to INT_MAX is explicitly different from an argument
+    // that clamps to INT_MAX.
+    ma_vcvt_F64_U32(input, scratchDouble.uintOverlay());
+    ma_vxfer(scratchDouble.uintOverlay(), output);
+    ma_mov(output, output, SetCC);
+    ma_b(bail, Signed);
+    ma_b(&fin);
+
+    bind(&handleZero);
+    // Move the top word of the double into the output reg, if it is non-zero,
+    // then the original value was -0.0.
+    as_vxfer(output, InvalidReg, input, FloatToCore, Always, 1);
+    as_cmp(output, Imm8(0));
+    ma_b(bail, NonZero);
+    ma_b(&fin);
+
+    bind(&handleNeg);
+    // Negative case, negate, then start dancing.
+    ma_vneg(input, input);
+    ma_vcvt_F64_U32(input, scratchDouble.uintOverlay());
+    ma_vxfer(scratchDouble.uintOverlay(), output);
+    ma_vcvt_U32_F64(scratchDouble.uintOverlay(), scratchDouble);
+    compareDouble(scratchDouble, input);
+    as_add(output, output, Imm8(1), LeaveCC, NotEqual);
+    // Negate the output. Since INT_MIN < -INT_MAX, even after adding 1, the
+    // result will still be a negative number.
+    as_rsb(output, output, Imm8(0), SetCC);
+    // Flip the negated input back to its original value.
+    ma_vneg(input, input);
+    // If the result looks non-negative, then this value didn't actually fit
+    // into the int range, and special handling is required. Zero is also caught
+    // by this case, but floor of a negative number should never be zero.
+    ma_b(bail, NotSigned);
+
+    bind(&fin);
+}
+
+void
+MacroAssemblerARMCompat::floorf(FloatRegister input, Register output, Label* bail)
+{
+    Label handleZero;
+    Label handleNeg;
+    Label fin;
+    compareFloat(input, NoVFPRegister);
+    ma_b(&handleZero, Assembler::Equal);
+    ma_b(&handleNeg, Assembler::Signed);
+    // NaN is always a bail condition, just bail directly.
+    ma_b(bail, Assembler::Overflow);
+
+    // The argument is a positive number, truncation is the path to glory; Since
+    // it is known to be > 0.0, explicitly convert to a larger range, then a
+    // value that rounds to INT_MAX is explicitly different from an argument
+    // that clamps to INT_MAX.
+    {
+        ScratchFloat32Scope scratch(asMasm());
+        ma_vcvt_F32_U32(input, scratch.uintOverlay());
+        ma_vxfer(VFPRegister(scratch).uintOverlay(), output);
+    }
+    ma_mov(output, output, SetCC);
+    ma_b(bail, Signed);
+    ma_b(&fin);
+
+    bind(&handleZero);
+    // Move the top word of the double into the output reg, if it is non-zero,
+    // then the original value was -0.0.
+    as_vxfer(output, InvalidReg, VFPRegister(input).singleOverlay(), FloatToCore, Always, 0);
+    as_cmp(output, Imm8(0));
+    ma_b(bail, NonZero);
+    ma_b(&fin);
+
+    bind(&handleNeg);
+    // Negative case, negate, then start dancing.
+    {
+        ScratchFloat32Scope scratch(asMasm());
+        ma_vneg_f32(input, input);
+        ma_vcvt_F32_U32(input, scratch.uintOverlay());
+        ma_vxfer(VFPRegister(scratch).uintOverlay(), output);
+        ma_vcvt_U32_F32(scratch.uintOverlay(), scratch);
+        compareFloat(scratch, input);
+        as_add(output, output, Imm8(1), LeaveCC, NotEqual);
+    }
+    // Negate the output. Since INT_MIN < -INT_MAX, even after adding 1, the
+    // result will still be a negative number.
+    as_rsb(output, output, Imm8(0), SetCC);
+    // Flip the negated input back to its original value.
+    ma_vneg_f32(input, input);
+    // If the result looks non-negative, then this value didn't actually fit
+    // into the int range, and special handling is required. Zero is also caught
+    // by this case, but floor of a negative number should never be zero.
+    ma_b(bail, NotSigned);
+
+    bind(&fin);
+}
+
+void
+MacroAssemblerARMCompat::ceil(FloatRegister input, Register output, Label* bail)
+{
+    Label handleZero;
+    Label handlePos;
+    Label fin;
+
+    compareDouble(input, NoVFPRegister);
+    // NaN is always a bail condition, just bail directly.
+    ma_b(bail, Assembler::Overflow);
+    ma_b(&handleZero, Assembler::Equal);
+    ma_b(&handlePos, Assembler::NotSigned);
+
+    ScratchDoubleScope scratchDouble(asMasm());
+
+    // We are in the ]-Inf; 0[ range
+    // If we are in the ]-1; 0[ range => bailout
+    loadConstantDouble(-1.0, scratchDouble);
+    compareDouble(input, scratchDouble);
+    ma_b(bail, Assembler::GreaterThan);
+
+    // We are in the ]-Inf; -1] range: ceil(x) == -floor(-x) and floor can be
+    // computed with direct truncation here (x > 0).
+    ma_vneg(input, scratchDouble);
+    FloatRegister ScratchUIntReg = scratchDouble.uintOverlay();
+    ma_vcvt_F64_U32(scratchDouble, ScratchUIntReg);
+    ma_vxfer(ScratchUIntReg, output);
+    ma_neg(output, output, SetCC);
+    ma_b(bail, NotSigned);
+    ma_b(&fin);
+
+    // Test for 0.0 / -0.0: if the top word of the input double is not zero,
+    // then it was -0 and we need to bail out.
+    bind(&handleZero);
+    as_vxfer(output, InvalidReg, input, FloatToCore, Always, 1);
+    as_cmp(output, Imm8(0));
+    ma_b(bail, NonZero);
+    ma_b(&fin);
+
+    // We are in the ]0; +inf] range: truncate integer values, maybe add 1 for
+    // non integer values, maybe bail if overflow.
+    bind(&handlePos);
+    ma_vcvt_F64_U32(input, ScratchUIntReg);
+    ma_vxfer(ScratchUIntReg, output);
+    ma_vcvt_U32_F64(ScratchUIntReg, scratchDouble);
+    compareDouble(scratchDouble, input);
+    as_add(output, output, Imm8(1), LeaveCC, NotEqual);
+    // Bail out if the add overflowed or the result is non positive.
+    ma_mov(output, output, SetCC);
+    ma_b(bail, Signed);
+    ma_b(bail, Zero);
+
+    bind(&fin);
+}
+
+void
+MacroAssemblerARMCompat::ceilf(FloatRegister input, Register output, Label* bail)
+{
+    Label handleZero;
+    Label handlePos;
+    Label fin;
+
+    compareFloat(input, NoVFPRegister);
+    // NaN is always a bail condition, just bail directly.
+    ma_b(bail, Assembler::Overflow);
+    ma_b(&handleZero, Assembler::Equal);
+    ma_b(&handlePos, Assembler::NotSigned);
+
+    // We are in the ]-Inf; 0[ range
+    // If we are in the ]-1; 0[ range => bailout
+    {
+        ScratchFloat32Scope scratch(asMasm());
+        loadConstantFloat32(-1.f, scratch);
+        compareFloat(input, scratch);
+        ma_b(bail, Assembler::GreaterThan);
+    }
+
+    // We are in the ]-Inf; -1] range: ceil(x) == -floor(-x) and floor can be
+    // computed with direct truncation here (x > 0).
+    {
+        ScratchDoubleScope scratchDouble(asMasm());
+        FloatRegister scratchFloat = scratchDouble.asSingle();
+        FloatRegister scratchUInt = scratchDouble.uintOverlay();
+
+        ma_vneg_f32(input, scratchFloat);
+        ma_vcvt_F32_U32(scratchFloat, scratchUInt);
+        ma_vxfer(scratchUInt, output);
+        ma_neg(output, output, SetCC);
+        ma_b(bail, NotSigned);
+        ma_b(&fin);
+    }
+
+    // Test for 0.0 / -0.0: if the top word of the input double is not zero,
+    // then it was -0 and we need to bail out.
+    bind(&handleZero);
+    as_vxfer(output, InvalidReg, VFPRegister(input).singleOverlay(), FloatToCore, Always, 0);
+    as_cmp(output, Imm8(0));
+    ma_b(bail, NonZero);
+    ma_b(&fin);
+
+    // We are in the ]0; +inf] range: truncate integer values, maybe add 1 for
+    // non integer values, maybe bail if overflow.
+    bind(&handlePos);
+    {
+        ScratchDoubleScope scratchDouble(asMasm());
+        FloatRegister scratchFloat = scratchDouble.asSingle();
+        FloatRegister scratchUInt = scratchDouble.uintOverlay();
+
+        ma_vcvt_F32_U32(input, scratchUInt);
+        ma_vxfer(scratchUInt, output);
+        ma_vcvt_U32_F32(scratchUInt, scratchFloat);
+        compareFloat(scratchFloat, input);
+        as_add(output, output, Imm8(1), LeaveCC, NotEqual);
+
+        // Bail on overflow or non-positive result.
+        ma_mov(output, output, SetCC);
+        ma_b(bail, Signed);
+        ma_b(bail, Zero);
+    }
+
+    bind(&fin);
+}
+
+CodeOffset
+MacroAssemblerARMCompat::toggledJump(Label* label)
+{
+    // Emit a B that can be toggled to a CMP. See ToggleToJmp(), ToggleToCmp().
+    BufferOffset b = ma_b(label, Always);
+    CodeOffset ret(b.getOffset());
+    return ret;
+}
+
+CodeOffset
+MacroAssemblerARMCompat::toggledCall(JitCode* target, bool enabled)
+{
+    BufferOffset bo = nextOffset();
+    addPendingJump(bo, ImmPtr(target->raw()), Relocation::JITCODE);
+    ScratchRegisterScope scratch(asMasm());
+    ma_movPatchable(ImmPtr(target->raw()), scratch, Always);
+    if (enabled)
+        ma_blx(scratch);
+    else
+        ma_nop();
+    return CodeOffset(bo.getOffset());
+}
+
+void
+MacroAssemblerARMCompat::round(FloatRegister input, Register output, Label* bail, FloatRegister tmp)
+{
+    Label handleZero;
+    Label handleNeg;
+    Label fin;
+
+    ScratchDoubleScope scratchDouble(asMasm());
+
+    // Do a compare based on the original value, then do most other things based
+    // on the shifted value.
+    ma_vcmpz(input);
+    // Since we already know the sign bit, flip all numbers to be positive,
+    // stored in tmp.
+    ma_vabs(input, tmp);
+    as_vmrs(pc);
+    ma_b(&handleZero, Assembler::Equal);
+    ma_b(&handleNeg, Assembler::Signed);
+    // NaN is always a bail condition, just bail directly.
+    ma_b(bail, Assembler::Overflow);
+
+    // The argument is a positive number, truncation is the path to glory; Since
+    // it is known to be > 0.0, explicitly convert to a larger range, then a
+    // value that rounds to INT_MAX is explicitly different from an argument
+    // that clamps to INT_MAX.
+
+    // Add the biggest number less than 0.5 (not 0.5, because adding that to
+    // the biggest number less than 0.5 would undesirably round up to 1), and
+    // store the result into tmp.
+    loadConstantDouble(GetBiggestNumberLessThan(0.5), scratchDouble);
+    ma_vadd(scratchDouble, tmp, tmp);
+
+    ma_vcvt_F64_U32(tmp, scratchDouble.uintOverlay());
+    ma_vxfer(VFPRegister(scratchDouble).uintOverlay(), output);
+    ma_mov(output, output, SetCC);
+    ma_b(bail, Signed);
+    ma_b(&fin);
+
+    bind(&handleZero);
+    // Move the top word of the double into the output reg, if it is non-zero,
+    // then the original value was -0.0
+    as_vxfer(output, InvalidReg, input, FloatToCore, Always, 1);
+    as_cmp(output, Imm8(0));
+    ma_b(bail, NonZero);
+    ma_b(&fin);
+
+    bind(&handleNeg);
+    // Negative case, negate, then start dancing. This number may be positive,
+    // since we added 0.5.
+
+    // Add 0.5 to negative numbers, store the result into tmp
+    loadConstantDouble(0.5, scratchDouble);
+    ma_vadd(scratchDouble, tmp, tmp);
+
+    ma_vcvt_F64_U32(tmp, scratchDouble.uintOverlay());
+    ma_vxfer(VFPRegister(scratchDouble).uintOverlay(), output);
+
+    // -output is now a correctly rounded value, unless the original value was
+    // exactly halfway between two integers, at which point, it has been rounded
+    // away from zero, when it should be rounded towards \infty.
+    ma_vcvt_U32_F64(scratchDouble.uintOverlay(), scratchDouble);
+    compareDouble(scratchDouble, tmp);
+    as_sub(output, output, Imm8(1), LeaveCC, Equal);
+    // Negate the output. Since INT_MIN < -INT_MAX, even after adding 1, the
+    // result will still be a negative number.
+    as_rsb(output, output, Imm8(0), SetCC);
+
+    // If the result looks non-negative, then this value didn't actually fit
+    // into the int range, and special handling is required, or it was zero,
+    // which means the result is actually -0.0 which also requires special
+    // handling.
+    ma_b(bail, NotSigned);
+
+    bind(&fin);
+}
+
+void
+MacroAssemblerARMCompat::roundf(FloatRegister input, Register output, Label* bail, FloatRegister tmp)
+{
+    Label handleZero;
+    Label handleNeg;
+    Label fin;
+
+    ScratchFloat32Scope scratchFloat(asMasm());
+
+    // Do a compare based on the original value, then do most other things based
+    // on the shifted value.
+    compareFloat(input, NoVFPRegister);
+    ma_b(&handleZero, Assembler::Equal);
+    ma_b(&handleNeg, Assembler::Signed);
+
+    // NaN is always a bail condition, just bail directly.
+    ma_b(bail, Assembler::Overflow);
+
+    // The argument is a positive number, truncation is the path to glory; Since
+    // it is known to be > 0.0, explicitly convert to a larger range, then a
+    // value that rounds to INT_MAX is explicitly different from an argument
+    // that clamps to INT_MAX.
+
+    // Add the biggest number less than 0.5f (not 0.5f, because adding that to
+    // the biggest number less than 0.5f would undesirably round up to 1), and
+    // store the result into tmp.
+    loadConstantFloat32(GetBiggestNumberLessThan(0.5f), scratchFloat);
+    ma_vadd_f32(scratchFloat, input, tmp);
+
+    // Note: it doesn't matter whether x + .5 === x or not here, as it doesn't
+    // affect the semantics of the float to unsigned conversion (in particular,
+    // we are not applying any fixup after the operation).
+    ma_vcvt_F32_U32(tmp, scratchFloat.uintOverlay());
+    ma_vxfer(VFPRegister(scratchFloat).uintOverlay(), output);
+    ma_mov(output, output, SetCC);
+    ma_b(bail, Signed);
+    ma_b(&fin);
+
+    bind(&handleZero);
+
+    // Move the whole float32 into the output reg, if it is non-zero, then the
+    // original value was -0.0.
+    as_vxfer(output, InvalidReg, input, FloatToCore, Always, 0);
+    as_cmp(output, Imm8(0));
+    ma_b(bail, NonZero);
+    ma_b(&fin);
+
+    bind(&handleNeg);
+
+    // Add 0.5 to negative numbers, storing the result into tmp.
+    ma_vneg_f32(input, tmp);
+    loadConstantFloat32(0.5f, scratchFloat);
+    ma_vadd_f32(tmp, scratchFloat, scratchFloat);
+
+    // Adding 0.5 to a float input has chances to yield the wrong result, if
+    // the input is too large. In this case, skip the -1 adjustment made below.
+    compareFloat(scratchFloat, tmp);
+
+    // Negative case, negate, then start dancing. This number may be positive,
+    // since we added 0.5.
+    // /!\ The conditional jump afterwards depends on these two instructions
+    //     *not* setting the status flags. They need to not change after the
+    //     comparison above.
+    ma_vcvt_F32_U32(scratchFloat, tmp.uintOverlay());
+    ma_vxfer(VFPRegister(tmp).uintOverlay(), output);
+
+    Label flipSign;
+    ma_b(&flipSign, Equal);
+
+    // -output is now a correctly rounded value, unless the original value was
+    // exactly halfway between two integers, at which point, it has been rounded
+    // away from zero, when it should be rounded towards \infty.
+    ma_vcvt_U32_F32(tmp.uintOverlay(), tmp);
+    compareFloat(tmp, scratchFloat);
+    as_sub(output, output, Imm8(1), LeaveCC, Equal);
+
+    // Negate the output. Since INT_MIN < -INT_MAX, even after adding 1, the
+    // result will still be a negative number.
+    bind(&flipSign);
+    as_rsb(output, output, Imm8(0), SetCC);
+
+    // If the result looks non-negative, then this value didn't actually fit
+    // into the int range, and special handling is required, or it was zero,
+    // which means the result is actually -0.0 which also requires special
+    // handling.
+    ma_b(bail, NotSigned);
+
+    bind(&fin);
+}
+
+CodeOffsetJump
+MacroAssemblerARMCompat::jumpWithPatch(RepatchLabel* label, Condition cond, Label* documentation)
+{
+    ARMBuffer::PoolEntry pe;
+    BufferOffset bo = as_BranchPool(0xdeadbeef, label, &pe, cond, documentation);
+    // Fill in a new CodeOffset with both the load and the pool entry that the
+    // instruction loads from.
+    CodeOffsetJump ret(bo.getOffset(), pe.index());
+    return ret;
+}
+
+namespace js {
+namespace jit {
+
+template<>
+Register
+MacroAssemblerARMCompat::computePointer<BaseIndex>(const BaseIndex& src, Register r)
+{
+    Register base = src.base;
+    Register index = src.index;
+    uint32_t scale = Imm32::ShiftOf(src.scale).value;
+    int32_t offset = src.offset;
+
+    ScratchRegisterScope scratch(asMasm());
+
+    as_add(r, base, lsl(index, scale));
+    if (offset != 0)
+        ma_add(r, Imm32(offset), r, scratch);
+    return r;
+}
+
+template<>
+Register
+MacroAssemblerARMCompat::computePointer<Address>(const Address& src, Register r)
+{
+    ScratchRegisterScope scratch(asMasm());
+    if (src.offset == 0)
+        return src.base;
+    ma_add(src.base, Imm32(src.offset), r, scratch);
+    return r;
+}
+
+} // namespace jit
+} // namespace js
+
+template<typename T>
+void
+MacroAssemblerARMCompat::compareExchange(int nbytes, bool signExtend, const T& mem,
+                                         Register oldval, Register newval, Register output)
+{
+    // If LDREXB/H and STREXB/H are not available we use the
+    // word-width operations with read-modify-add.  That does not
+    // abstract well, so fork.
+    //
+    // Bug 1077321: We may further optimize for ARMv8 (AArch32) here.
+    if (nbytes < 4 && !HasLDSTREXBHD())
+        compareExchangeARMv6(nbytes, signExtend, mem, oldval, newval, output);
+    else
+        compareExchangeARMv7(nbytes, signExtend, mem, oldval, newval, output);
+}
+
+// General algorithm:
+//
+//     ...    ptr, <addr>         ; compute address of item
+//     dmb
+// L0  ldrex* output, [ptr]
+//     sxt*   output, output, 0   ; sign-extend if applicable
+//     *xt*   tmp, oldval, 0      ; sign-extend or zero-extend if applicable
+//     cmp    output, tmp
+//     bne    L1                  ; failed - values are different
+//     strex* tmp, newval, [ptr]
+//     cmp    tmp, 1
+//     beq    L0                  ; failed - location is dirty, retry
+// L1  dmb
+//
+// Discussion here:  http://www.cl.cam.ac.uk/~pes20/cpp/cpp0xmappings.html.
+// However note that that discussion uses 'isb' as the trailing fence.
+// I've not quite figured out why, and I've gone with dmb here which
+// is safe.  Also see the LLVM source, which uses 'dmb ish' generally.
+// (Apple's Swift CPU apparently handles ish in a non-default, faster
+// way.)
+
+template<typename T>
+void
+MacroAssemblerARMCompat::compareExchangeARMv7(int nbytes, bool signExtend, const T& mem,
+                                              Register oldval, Register newval, Register output)
+{
+    Label again;
+    Label done;
+    ma_dmb(BarrierST);
+
+    SecondScratchRegisterScope scratch2(asMasm());
+    Register ptr = computePointer(mem, scratch2);
+
+    ScratchRegisterScope scratch(asMasm());
+
+    bind(&again);
+    switch (nbytes) {
+      case 1:
+        as_ldrexb(output, ptr);
+        if (signExtend) {
+            as_sxtb(output, output, 0);
+            as_sxtb(scratch, oldval, 0);
+        } else {
+            as_uxtb(scratch, oldval, 0);
+        }
+        break;
+      case 2:
+        as_ldrexh(output, ptr);
+        if (signExtend) {
+            as_sxth(output, output, 0);
+            as_sxth(scratch, oldval, 0);
+        } else {
+            as_uxth(scratch, oldval, 0);
+        }
+        break;
+      case 4:
+        MOZ_ASSERT(!signExtend);
+        as_ldrex(output, ptr);
+        break;
+    }
+    if (nbytes < 4)
+        as_cmp(output, O2Reg(scratch));
+    else
+        as_cmp(output, O2Reg(oldval));
+    as_b(&done, NotEqual);
+    switch (nbytes) {
+      case 1:
+        as_strexb(scratch, newval, ptr);
+        break;
+      case 2:
+        as_strexh(scratch, newval, ptr);
+        break;
+      case 4:
+        as_strex(scratch, newval, ptr);
+        break;
+    }
+    as_cmp(scratch, Imm8(1));
+    as_b(&again, Equal);
+    bind(&done);
+    ma_dmb();
+}
+
+template<typename T>
+void
+MacroAssemblerARMCompat::compareExchangeARMv6(int nbytes, bool signExtend, const T& mem,
+                                              Register oldval, Register newval, Register output)
+{
+    // Bug 1077318: Must use read-modify-write with LDREX / STREX.
+    MOZ_ASSERT(nbytes == 1 || nbytes == 2);
+    MOZ_CRASH("NYI");
+}
+
+template void
+js::jit::MacroAssemblerARMCompat::compareExchange(int nbytes, bool signExtend,
+                                                  const Address& address, Register oldval,
+                                                  Register newval, Register output);
+template void
+js::jit::MacroAssemblerARMCompat::compareExchange(int nbytes, bool signExtend,
+                                                  const BaseIndex& address, Register oldval,
+                                                  Register newval, Register output);
+
+template<typename T>
+void
+MacroAssemblerARMCompat::atomicExchange(int nbytes, bool signExtend, const T& mem,
+                                        Register value, Register output)
+{
+    // If LDREXB/H and STREXB/H are not available we use the
+    // word-width operations with read-modify-add.  That does not
+    // abstract well, so fork.
+    //
+    // Bug 1077321: We may further optimize for ARMv8 (AArch32) here.
+    if (nbytes < 4 && !HasLDSTREXBHD())
+        atomicExchangeARMv6(nbytes, signExtend, mem, value, output);
+    else
+        atomicExchangeARMv7(nbytes, signExtend, mem, value, output);
+}
+
+template<typename T>
+void
+MacroAssemblerARMCompat::atomicExchangeARMv7(int nbytes, bool signExtend, const T& mem,
+                                             Register value, Register output)
+{
+    Label again;
+    Label done;
+    ma_dmb(BarrierST);
+
+    SecondScratchRegisterScope scratch2(asMasm());
+    Register ptr = computePointer(mem, scratch2);
+
+    ScratchRegisterScope scratch(asMasm());
+
+    bind(&again);
+    switch (nbytes) {
+      case 1:
+        as_ldrexb(output, ptr);
+        if (signExtend)
+            as_sxtb(output, output, 0);
+        as_strexb(scratch, value, ptr);
+        break;
+      case 2:
+        as_ldrexh(output, ptr);
+        if (signExtend)
+            as_sxth(output, output, 0);
+        as_strexh(scratch, value, ptr);
+        break;
+      case 4:
+        MOZ_ASSERT(!signExtend);
+        as_ldrex(output, ptr);
+        as_strex(scratch, value, ptr);
+        break;
+      default:
+        MOZ_CRASH();
+    }
+    as_cmp(scratch, Imm8(1));
+    as_b(&again, Equal);
+    bind(&done);
+    ma_dmb();
+}
+
+template<typename T>
+void
+MacroAssemblerARMCompat::atomicExchangeARMv6(int nbytes, bool signExtend, const T& mem,
+                                             Register value, Register output)
+{
+    // Bug 1077318: Must use read-modify-write with LDREX / STREX.
+    MOZ_ASSERT(nbytes == 1 || nbytes == 2);
+    MOZ_CRASH("NYI");
+}
+
+template void
+js::jit::MacroAssemblerARMCompat::atomicExchange(int nbytes, bool signExtend,
+                                                 const Address& address, Register value,
+                                                 Register output);
+template void
+js::jit::MacroAssemblerARMCompat::atomicExchange(int nbytes, bool signExtend,
+                                                 const BaseIndex& address, Register value,
+                                                 Register output);
+
+template<typename T>
+void
+MacroAssemblerARMCompat::atomicFetchOp(int nbytes, bool signExtend, AtomicOp op, const Imm32& value,
+                                       const T& mem, Register flagTemp, Register output)
+{
+    // The Imm32 case is not needed yet because lowering always forces
+    // the value into a register at present (bug 1077317).
+    //
+    // This would be useful for immediates small enough to fit into
+    // add/sub/and/or/xor.
+    MOZ_CRASH("Feature NYI");
+}
+
+// General algorithm:
+//
+//     ...    ptr, <addr>         ; compute address of item
+//     dmb
+// L0  ldrex* output, [ptr]
+//     sxt*   output, output, 0   ; sign-extend if applicable
+//     OP     tmp, output, value  ; compute value to store
+//     strex* tmp2, tmp, [ptr]    ; tmp2 required by strex
+//     cmp    tmp2, 1
+//     beq    L0                  ; failed - location is dirty, retry
+//     dmb                        ; ordering barrier required
+//
+// Also see notes above at compareExchange re the barrier strategy.
+//
+// Observe that the value being operated into the memory element need
+// not be sign-extended because no OP will make use of bits to the
+// left of the bits indicated by the width of the element, and neither
+// output nor the bits stored are affected by OP.
+
+template<typename T>
+void
+MacroAssemblerARMCompat::atomicFetchOp(int nbytes, bool signExtend, AtomicOp op,
+                                       const Register& value, const T& mem, Register flagTemp,
+                                       Register output)
+{
+    // Fork for non-word operations on ARMv6.
+    //
+    // Bug 1077321: We may further optimize for ARMv8 (AArch32) here.
+    if (nbytes < 4 && !HasLDSTREXBHD())
+        atomicFetchOpARMv6(nbytes, signExtend, op, value, mem, flagTemp, output);
+    else
+        atomicFetchOpARMv7(nbytes, signExtend, op, value, mem, flagTemp, output);
+}
+
+template<typename T>
+void
+MacroAssemblerARMCompat::atomicFetchOpARMv7(int nbytes, bool signExtend, AtomicOp op,
+                                            const Register& value, const T& mem, Register flagTemp,
+                                            Register output)
+{
+    MOZ_ASSERT(flagTemp != InvalidReg);
+
+    Label again;
+
+    SecondScratchRegisterScope scratch2(asMasm());
+    Register ptr = computePointer(mem, scratch2);
+
+    ma_dmb();
+
+    ScratchRegisterScope scratch(asMasm());
+
+    bind(&again);
+    switch (nbytes) {
+      case 1:
+        as_ldrexb(output, ptr);
+        if (signExtend)
+            as_sxtb(output, output, 0);
+        break;
+      case 2:
+        as_ldrexh(output, ptr);
+        if (signExtend)
+            as_sxth(output, output, 0);
+        break;
+      case 4:
+        MOZ_ASSERT(!signExtend);
+        as_ldrex(output, ptr);
+        break;
+    }
+    switch (op) {
+      case AtomicFetchAddOp:
+        as_add(scratch, output, O2Reg(value));
+        break;
+      case AtomicFetchSubOp:
+        as_sub(scratch, output, O2Reg(value));
+        break;
+      case AtomicFetchAndOp:
+        as_and(scratch, output, O2Reg(value));
+        break;
+      case AtomicFetchOrOp:
+        as_orr(scratch, output, O2Reg(value));
+        break;
+      case AtomicFetchXorOp:
+        as_eor(scratch, output, O2Reg(value));
+        break;
+    }
+    // Rd must differ from the two other arguments to strex.
+    switch (nbytes) {
+      case 1:
+        as_strexb(flagTemp, scratch, ptr);
+        break;
+      case 2:
+        as_strexh(flagTemp, scratch, ptr);
+        break;
+      case 4:
+        as_strex(flagTemp, scratch, ptr);
+        break;
+    }
+    as_cmp(flagTemp, Imm8(1));
+    as_b(&again, Equal);
+    ma_dmb();
+}
+
+template<typename T>
+void
+MacroAssemblerARMCompat::atomicFetchOpARMv6(int nbytes, bool signExtend, AtomicOp op,
+                                            const Register& value, const T& mem, Register flagTemp,
+                                            Register output)
+{
+    // Bug 1077318: Must use read-modify-write with LDREX / STREX.
+    MOZ_ASSERT(nbytes == 1 || nbytes == 2);
+    MOZ_CRASH("NYI");
+}
+
+template<typename T>
+void
+MacroAssemblerARMCompat::atomicEffectOp(int nbytes, AtomicOp op, const Register& value,
+                                        const T& mem, Register flagTemp)
+{
+    // Fork for non-word operations on ARMv6.
+    //
+    // Bug 1077321: We may further optimize for ARMv8 (AArch32) here.
+    if (nbytes < 4 && !HasLDSTREXBHD())
+        atomicEffectOpARMv6(nbytes, op, value, mem, flagTemp);
+    else
+        atomicEffectOpARMv7(nbytes, op, value, mem, flagTemp);
+}
+
+template<typename T>
+void
+MacroAssemblerARMCompat::atomicEffectOp(int nbytes, AtomicOp op, const Imm32& value,
+                                        const T& mem, Register flagTemp)
+{
+    // The Imm32 case is not needed yet because lowering always forces
+    // the value into a register at present (bug 1077317).
+    //
+    // This would be useful for immediates small enough to fit into
+    // add/sub/and/or/xor.
+    MOZ_CRASH("NYI");
+}
+
+// Uses both scratch registers, one for the address and one for a temp,
+// but needs two temps for strex:
+//
+//     ...    ptr, <addr>         ; compute address of item
+//     dmb
+// L0  ldrex* temp, [ptr]
+//     OP     temp, temp, value   ; compute value to store
+//     strex* temp2, temp, [ptr]
+//     cmp    temp2, 1
+//     beq    L0                  ; failed - location is dirty, retry
+//     dmb                        ; ordering barrier required
+
+template<typename T>
+void
+MacroAssemblerARMCompat::atomicEffectOpARMv7(int nbytes, AtomicOp op, const Register& value,
+                                             const T& mem, Register flagTemp)
+{
+    MOZ_ASSERT(flagTemp != InvalidReg);
+
+    Label again;
+
+    SecondScratchRegisterScope scratch2(asMasm());
+    Register ptr = computePointer(mem, scratch2);
+
+    ma_dmb();
+
+    ScratchRegisterScope scratch(asMasm());
+
+    bind(&again);
+    switch (nbytes) {
+      case 1:
+        as_ldrexb(scratch, ptr);
+        break;
+      case 2:
+        as_ldrexh(scratch, ptr);
+        break;
+      case 4:
+        as_ldrex(scratch, ptr);
+        break;
+    }
+    switch (op) {
+      case AtomicFetchAddOp:
+        as_add(scratch, scratch, O2Reg(value));
+        break;
+      case AtomicFetchSubOp:
+        as_sub(scratch, scratch, O2Reg(value));
+        break;
+      case AtomicFetchAndOp:
+        as_and(scratch, scratch, O2Reg(value));
+        break;
+      case AtomicFetchOrOp:
+        as_orr(scratch, scratch, O2Reg(value));
+        break;
+      case AtomicFetchXorOp:
+        as_eor(scratch, scratch, O2Reg(value));
+        break;
+    }
+    // Rd must differ from the two other arguments to strex.
+    switch (nbytes) {
+      case 1:
+        as_strexb(flagTemp, scratch, ptr);
+        break;
+      case 2:
+        as_strexh(flagTemp, scratch, ptr);
+        break;
+      case 4:
+        as_strex(flagTemp, scratch, ptr);
+        break;
+    }
+    as_cmp(flagTemp, Imm8(1));
+    as_b(&again, Equal);
+    ma_dmb();
+}
+
+template<typename T>
+void
+MacroAssemblerARMCompat::atomicEffectOpARMv6(int nbytes, AtomicOp op, const Register& value,
+                                             const T& mem, Register flagTemp)
+{
+    // Bug 1077318: Must use read-modify-write with LDREX / STREX.
+    MOZ_ASSERT(nbytes == 1 || nbytes == 2);
+    MOZ_CRASH("NYI");
+}
+
+template void
+js::jit::MacroAssemblerARMCompat::atomicFetchOp(int nbytes, bool signExtend, AtomicOp op,
+                                                const Imm32& value, const Address& mem,
+                                                Register flagTemp, Register output);
+template void
+js::jit::MacroAssemblerARMCompat::atomicFetchOp(int nbytes, bool signExtend, AtomicOp op,
+                                                const Imm32& value, const BaseIndex& mem,
+                                                Register flagTemp, Register output);
+template void
+js::jit::MacroAssemblerARMCompat::atomicFetchOp(int nbytes, bool signExtend, AtomicOp op,
+                                                const Register& value, const Address& mem,
+                                                Register flagTemp, Register output);
+template void
+js::jit::MacroAssemblerARMCompat::atomicFetchOp(int nbytes, bool signExtend, AtomicOp op,
+                                                const Register& value, const BaseIndex& mem,
+                                                Register flagTemp, Register output);
+
+template void
+js::jit::MacroAssemblerARMCompat::atomicEffectOp(int nbytes, AtomicOp op, const Imm32& value,
+                                                 const Address& mem, Register flagTemp);
+template void
+js::jit::MacroAssemblerARMCompat::atomicEffectOp(int nbytes, AtomicOp op, const Imm32& value,
+                                                 const BaseIndex& mem, Register flagTemp);
+template void
+js::jit::MacroAssemblerARMCompat::atomicEffectOp(int nbytes, AtomicOp op, const Register& value,
+                                                 const Address& mem, Register flagTemp);
+template void
+js::jit::MacroAssemblerARMCompat::atomicEffectOp(int nbytes, AtomicOp op, const Register& value,
+                                                 const BaseIndex& mem, Register flagTemp);
+
+template<typename T>
+void
+MacroAssemblerARMCompat::compareExchangeToTypedIntArray(Scalar::Type arrayType, const T& mem,
+                                                        Register oldval, Register newval,
+                                                        Register temp, AnyRegister output)
+{
+    switch (arrayType) {
+      case Scalar::Int8:
+        compareExchange8SignExtend(mem, oldval, newval, output.gpr());
+        break;
+      case Scalar::Uint8:
+        compareExchange8ZeroExtend(mem, oldval, newval, output.gpr());
+        break;
+      case Scalar::Int16:
+        compareExchange16SignExtend(mem, oldval, newval, output.gpr());
+        break;
+      case Scalar::Uint16:
+        compareExchange16ZeroExtend(mem, oldval, newval, output.gpr());
+        break;
+      case Scalar::Int32:
+        compareExchange32(mem, oldval, newval, output.gpr());
+        break;
+      case Scalar::Uint32:
+        // At the moment, the code in MCallOptimize.cpp requires the output
+        // type to be double for uint32 arrays.  See bug 1077305.
+        MOZ_ASSERT(output.isFloat());
+        compareExchange32(mem, oldval, newval, temp);
+        convertUInt32ToDouble(temp, output.fpu());
+        break;
+      default:
+        MOZ_CRASH("Invalid typed array type");
+    }
+}
+
+template void
+MacroAssemblerARMCompat::compareExchangeToTypedIntArray(Scalar::Type arrayType, const Address& mem,
+                                                        Register oldval, Register newval, Register temp,
+                                                        AnyRegister output);
+template void
+MacroAssemblerARMCompat::compareExchangeToTypedIntArray(Scalar::Type arrayType, const BaseIndex& mem,
+                                                        Register oldval, Register newval, Register temp,
+                                                        AnyRegister output);
+
+template<typename T>
+void
+MacroAssemblerARMCompat::atomicExchangeToTypedIntArray(Scalar::Type arrayType, const T& mem,
+                                                       Register value, Register temp, AnyRegister output)
+{
+    switch (arrayType) {
+      case Scalar::Int8:
+        atomicExchange8SignExtend(mem, value, output.gpr());
+        break;
+      case Scalar::Uint8:
+        atomicExchange8ZeroExtend(mem, value, output.gpr());
+        break;
+      case Scalar::Int16:
+        atomicExchange16SignExtend(mem, value, output.gpr());
+        break;
+      case Scalar::Uint16:
+        atomicExchange16ZeroExtend(mem, value, output.gpr());
+        break;
+      case Scalar::Int32:
+        atomicExchange32(mem, value, output.gpr());
+        break;
+      case Scalar::Uint32:
+        // At the moment, the code in MCallOptimize.cpp requires the output
+        // type to be double for uint32 arrays.  See bug 1077305.
+        MOZ_ASSERT(output.isFloat());
+        atomicExchange32(mem, value, temp);
+        convertUInt32ToDouble(temp, output.fpu());
+        break;
+      default:
+        MOZ_CRASH("Invalid typed array type");
+    }
+}
+
+template void
+MacroAssemblerARMCompat::atomicExchangeToTypedIntArray(Scalar::Type arrayType, const Address& mem,
+                                                       Register value, Register temp, AnyRegister output);
+template void
+MacroAssemblerARMCompat::atomicExchangeToTypedIntArray(Scalar::Type arrayType, const BaseIndex& mem,
+                                                       Register value, Register temp, AnyRegister output);
+
+void
+MacroAssemblerARMCompat::profilerEnterFrame(Register framePtr, Register scratch)
+{
+    AbsoluteAddress activation(GetJitContext()->runtime->addressOfProfilingActivation());
+    loadPtr(activation, scratch);
+    storePtr(framePtr, Address(scratch, JitActivation::offsetOfLastProfilingFrame()));
+    storePtr(ImmPtr(nullptr), Address(scratch, JitActivation::offsetOfLastProfilingCallSite()));
+}
+
+void
+MacroAssemblerARMCompat::profilerExitFrame()
+{
+    branch(GetJitContext()->runtime->jitRuntime()->getProfilerExitFrameTail());
+}
+
+MacroAssembler&
+MacroAssemblerARM::asMasm()
+{
+    return *static_cast<MacroAssembler*>(this);
+}
+
+const MacroAssembler&
+MacroAssemblerARM::asMasm() const
+{
+    return *static_cast<const MacroAssembler*>(this);
+}
+
+MacroAssembler&
+MacroAssemblerARMCompat::asMasm()
+{
+    return *static_cast<MacroAssembler*>(this);
+}
+
+const MacroAssembler&
+MacroAssemblerARMCompat::asMasm() const
+{
+    return *static_cast<const MacroAssembler*>(this);
+}
+
+void
+MacroAssembler::subFromStackPtr(Imm32 imm32)
+{
+    ScratchRegisterScope scratch(*this);
+    if (imm32.value)
+        ma_sub(imm32, sp, scratch);
+}
+
+//{{{ check_macroassembler_style
+// ===============================================================
+// MacroAssembler high-level usage.
+
+void
+MacroAssembler::flush()
+{
+    Assembler::flush();
+}
+
+void
+MacroAssembler::comment(const char* msg)
+{
+    Assembler::comment(msg);
+}
+
+// ===============================================================
+// Stack manipulation functions.
+
+void
+MacroAssembler::PushRegsInMask(LiveRegisterSet set)
+{
+    int32_t diffF = set.fpus().getPushSizeInBytes();
+    int32_t diffG = set.gprs().size() * sizeof(intptr_t);
+
+    if (set.gprs().size() > 1) {
+        adjustFrame(diffG);
+        startDataTransferM(IsStore, StackPointer, DB, WriteBack);
+        for (GeneralRegisterBackwardIterator iter(set.gprs()); iter.more(); ++iter) {
+            diffG -= sizeof(intptr_t);
+            transferReg(*iter);
+        }
+        finishDataTransfer();
+    } else {
+        reserveStack(diffG);
+        for (GeneralRegisterBackwardIterator iter(set.gprs()); iter.more(); ++iter) {
+            diffG -= sizeof(intptr_t);
+            storePtr(*iter, Address(StackPointer, diffG));
+        }
+    }
+    MOZ_ASSERT(diffG == 0);
+
+    adjustFrame(diffF);
+    diffF += transferMultipleByRuns(set.fpus(), IsStore, StackPointer, DB);
+    MOZ_ASSERT(diffF == 0);
+}
+
+void
+MacroAssembler::PopRegsInMaskIgnore(LiveRegisterSet set, LiveRegisterSet ignore)
+{
+    int32_t diffG = set.gprs().size() * sizeof(intptr_t);
+    int32_t diffF = set.fpus().getPushSizeInBytes();
+    const int32_t reservedG = diffG;
+    const int32_t reservedF = diffF;
+
+    // ARM can load multiple registers at once, but only if we want back all
+    // the registers we previously saved to the stack.
+    if (ignore.emptyFloat()) {
+        diffF -= transferMultipleByRuns(set.fpus(), IsLoad, StackPointer, IA);
+        adjustFrame(-reservedF);
+    } else {
+        LiveFloatRegisterSet fpset(set.fpus().reduceSetForPush());
+        LiveFloatRegisterSet fpignore(ignore.fpus().reduceSetForPush());
+        for (FloatRegisterBackwardIterator iter(fpset); iter.more(); ++iter) {
+            diffF -= (*iter).size();
+            if (!fpignore.has(*iter))
+                loadDouble(Address(StackPointer, diffF), *iter);
+        }
+        freeStack(reservedF);
+    }
+    MOZ_ASSERT(diffF == 0);
+
+    if (set.gprs().size() > 1 && ignore.emptyGeneral()) {
+        startDataTransferM(IsLoad, StackPointer, IA, WriteBack);
+        for (GeneralRegisterBackwardIterator iter(set.gprs()); iter.more(); ++iter) {
+            diffG -= sizeof(intptr_t);
+            transferReg(*iter);
+        }
+        finishDataTransfer();
+        adjustFrame(-reservedG);
+    } else {
+        for (GeneralRegisterBackwardIterator iter(set.gprs()); iter.more(); ++iter) {
+            diffG -= sizeof(intptr_t);
+            if (!ignore.has(*iter))
+                loadPtr(Address(StackPointer, diffG), *iter);
+        }
+        freeStack(reservedG);
+    }
+    MOZ_ASSERT(diffG == 0);
+}
+
+void
+MacroAssembler::Push(Register reg)
+{
+    push(reg);
+    adjustFrame(sizeof(intptr_t));
+}
+
+void
+MacroAssembler::Push(const Imm32 imm)
+{
+    push(imm);
+    adjustFrame(sizeof(intptr_t));
+}
+
+void
+MacroAssembler::Push(const ImmWord imm)
+{
+    push(imm);
+    adjustFrame(sizeof(intptr_t));
+}
+
+void
+MacroAssembler::Push(const ImmPtr imm)
+{
+    Push(ImmWord(uintptr_t(imm.value)));
+}
+
+void
+MacroAssembler::Push(const ImmGCPtr ptr)
+{
+    push(ptr);
+    adjustFrame(sizeof(intptr_t));
+}
+
+void
+MacroAssembler::Push(FloatRegister reg)
+{
+    VFPRegister r = VFPRegister(reg);
+    ma_vpush(VFPRegister(reg));
+    adjustFrame(r.size());
+}
+
+void
+MacroAssembler::Pop(Register reg)
+{
+    ma_pop(reg);
+    adjustFrame(-sizeof(intptr_t));
+}
+
+void
+MacroAssembler::Pop(FloatRegister reg)
+{
+    ma_vpop(reg);
+    adjustFrame(-reg.size());
+}
+
+void
+MacroAssembler::Pop(const ValueOperand& val)
+{
+    popValue(val);
+    adjustFrame(-sizeof(Value));
+}
+
+// ===============================================================
+// Simple call functions.
+
+CodeOffset
+MacroAssembler::call(Register reg)
+{
+    as_blx(reg);
+    return CodeOffset(currentOffset());
+}
+
+CodeOffset
+MacroAssembler::call(Label* label)
+{
+    // For now, assume that it'll be nearby.
+    as_bl(label, Always);
+    return CodeOffset(currentOffset());
+}
+
+void
+MacroAssembler::call(ImmWord imm)
+{
+    call(ImmPtr((void*)imm.value));
+}
+
+void
+MacroAssembler::call(ImmPtr imm)
+{
+    BufferOffset bo = m_buffer.nextOffset();
+    addPendingJump(bo, imm, Relocation::HARDCODED);
+    ma_call(imm);
+}
+
+void
+MacroAssembler::call(wasm::SymbolicAddress imm)
+{
+    movePtr(imm, CallReg);
+    call(CallReg);
+}
+
+void
+MacroAssembler::call(JitCode* c)
+{
+    BufferOffset bo = m_buffer.nextOffset();
+    addPendingJump(bo, ImmPtr(c->raw()), Relocation::JITCODE);
+    ScratchRegisterScope scratch(*this);
+    ma_movPatchable(ImmPtr(c->raw()), scratch, Always);
+    callJitNoProfiler(scratch);
+}
+
+CodeOffset
+MacroAssembler::callWithPatch()
+{
+    // The caller ensures that the call is always in range using thunks (below)
+    // as necessary.
+    as_bl(BOffImm(), Always, /* documentation */ nullptr);
+    return CodeOffset(currentOffset());
+}
+
+void
+MacroAssembler::patchCall(uint32_t callerOffset, uint32_t calleeOffset)
+{
+    BufferOffset inst(callerOffset - 4);
+    as_bl(BufferOffset(calleeOffset).diffB<BOffImm>(inst), Always, inst);
+}
+
+CodeOffset
+MacroAssembler::farJumpWithPatch()
+{
+    static_assert(32 * 1024 * 1024 - JumpImmediateRange > wasm::MaxFuncs * 3 * sizeof(Instruction),
+                  "always enough space for thunks");
+
+    // The goal of the thunk is to be able to jump to any address without the
+    // usual 32MiB branch range limitation. Additionally, to make the thunk
+    // simple to use, the thunk does not use the constant pool or require
+    // patching an absolute address. Instead, a relative offset is used which
+    // can be patched during compilation.
+
+    // Inhibit pools since these three words must be contiguous so that the offset
+    // calculations below are valid.
+    AutoForbidPools afp(this, 3);
+
+    // When pc is used, the read value is the address of the instruction + 8.
+    // This is exactly the address of the uint32 word we want to load.
+    ScratchRegisterScope scratch(*this);
+    ma_ldr(DTRAddr(pc, DtrOffImm(0)), scratch);
+
+    // Branch by making pc the destination register.
+    ma_add(pc, scratch, pc, LeaveCC, Always);
+
+    // Allocate space which will be patched by patchFarJump().
+    CodeOffset farJump(currentOffset());
+    writeInst(UINT32_MAX);
+
+    return farJump;
+}
+
+void
+MacroAssembler::patchFarJump(CodeOffset farJump, uint32_t targetOffset)
+{
+    uint32_t* u32 = reinterpret_cast<uint32_t*>(editSrc(BufferOffset(farJump.offset())));
+    MOZ_ASSERT(*u32 == UINT32_MAX);
+
+    uint32_t addOffset = farJump.offset() - 4;
+    MOZ_ASSERT(editSrc(BufferOffset(addOffset))->is<InstALU>());
+
+    // When pc is read as the operand of the add, its value is the address of
+    // the add instruction + 8.
+    *u32 = (targetOffset - addOffset) - 8;
+}
+
+void
+MacroAssembler::repatchFarJump(uint8_t* code, uint32_t farJumpOffset, uint32_t targetOffset)
+{
+    uint32_t* u32 = reinterpret_cast<uint32_t*>(code + farJumpOffset);
+
+    uint32_t addOffset = farJumpOffset - 4;
+    MOZ_ASSERT(reinterpret_cast<Instruction*>(code + addOffset)->is<InstALU>());
+
+    *u32 = (targetOffset - addOffset) - 8;
+}
+
+CodeOffset
+MacroAssembler::nopPatchableToNearJump()
+{
+    // Inhibit pools so that the offset points precisely to the nop.
+    AutoForbidPools afp(this, 1);
+
+    CodeOffset offset(currentOffset());
+    ma_nop();
+    return offset;
+}
+
+void
+MacroAssembler::patchNopToNearJump(uint8_t* jump, uint8_t* target)
+{
+    MOZ_ASSERT(reinterpret_cast<Instruction*>(jump)->is<InstNOP>());
+    new (jump) InstBImm(BOffImm(target - jump), Assembler::Always);
+}
+
+void
+MacroAssembler::patchNearJumpToNop(uint8_t* jump)
+{
+    MOZ_ASSERT(reinterpret_cast<Instruction*>(jump)->is<InstBImm>());
+    new (jump) InstNOP();
+}
+
+void
+MacroAssembler::pushReturnAddress()
+{
+    push(lr);
+}
+
+void
+MacroAssembler::popReturnAddress()
+{
+    pop(lr);
+}
+
+// ===============================================================
+// ABI function calls.
+
+void
+MacroAssembler::setupUnalignedABICall(Register scratch)
+{
+    setupABICall();
+    dynamicAlignment_ = true;
+
+    ma_mov(sp, scratch);
+    // Force sp to be aligned.
+    as_bic(sp, sp, Imm8(ABIStackAlignment - 1));
+    ma_push(scratch);
+}
+
+void
+MacroAssembler::callWithABIPre(uint32_t* stackAdjust, bool callFromWasm)
+{
+    MOZ_ASSERT(inCall_);
+    uint32_t stackForCall = abiArgs_.stackBytesConsumedSoFar();
+
+    if (dynamicAlignment_) {
+        // sizeof(intptr_t) accounts for the saved stack pointer pushed by
+        // setupUnalignedABICall.
+        stackForCall += ComputeByteAlignment(stackForCall + sizeof(intptr_t),
+                                             ABIStackAlignment);
+    } else {
+        uint32_t alignmentAtPrologue = callFromWasm ? sizeof(wasm::Frame) : 0;
+        stackForCall += ComputeByteAlignment(stackForCall + framePushed() + alignmentAtPrologue,
+                                             ABIStackAlignment);
+    }
+
+    *stackAdjust = stackForCall;
+    reserveStack(stackForCall);
+
+    // Position all arguments.
+    {
+        enoughMemory_ = enoughMemory_ && moveResolver_.resolve();
+        if (!enoughMemory_)
+            return;
+
+        MoveEmitter emitter(*this);
+        emitter.emit(moveResolver_);
+        emitter.finish();
+    }
+
+    assertStackAlignment(ABIStackAlignment);
+
+    // Save the lr register if we need to preserve it.
+    if (secondScratchReg_ != lr)
+        ma_mov(lr, secondScratchReg_);
+}
+
+void
+MacroAssembler::callWithABIPost(uint32_t stackAdjust, MoveOp::Type result)
+{
+    if (secondScratchReg_ != lr)
+        ma_mov(secondScratchReg_, lr);
+
+    switch (result) {
+      case MoveOp::DOUBLE:
+        if (!UseHardFpABI()) {
+            // Move double from r0/r1 to ReturnFloatReg.
+            ma_vxfer(r0, r1, ReturnDoubleReg);
+        }
+        break;
+      case MoveOp::FLOAT32:
+        if (!UseHardFpABI()) {
+            // Move float32 from r0 to ReturnFloatReg.
+            ma_vxfer(r0, ReturnFloat32Reg.singleOverlay());
+        }
+        break;
+      case MoveOp::GENERAL:
+        break;
+
+      default:
+        MOZ_CRASH("unexpected callWithABI result");
+    }
+
+    freeStack(stackAdjust);
+
+    if (dynamicAlignment_) {
+        // While the x86 supports pop esp, on ARM that isn't well defined, so
+        // just do it manually.
+        as_dtr(IsLoad, 32, Offset, sp, DTRAddr(sp, DtrOffImm(0)));
+    }
+
+#ifdef DEBUG
+    MOZ_ASSERT(inCall_);
+    inCall_ = false;
+#endif
+}
+
+void
+MacroAssembler::callWithABINoProfiler(Register fun, MoveOp::Type result)
+{
+    // Load the callee in r12, as above.
+    ma_mov(fun, r12);
+    uint32_t stackAdjust;
+    callWithABIPre(&stackAdjust);
+    call(r12);
+    callWithABIPost(stackAdjust, result);
+}
+
+void
+MacroAssembler::callWithABINoProfiler(const Address& fun, MoveOp::Type result)
+{
+    // Load the callee in r12, no instruction between the ldr and call should
+    // clobber it. Note that we can't use fun.base because it may be one of the
+    // IntArg registers clobbered before the call.
+    {
+        ScratchRegisterScope scratch(*this);
+        ma_ldr(fun, r12, scratch);
+    }
+    uint32_t stackAdjust;
+    callWithABIPre(&stackAdjust);
+    call(r12);
+    callWithABIPost(stackAdjust, result);
+}
+
+// ===============================================================
+// Jit Frames.
+
+uint32_t
+MacroAssembler::pushFakeReturnAddress(Register scratch)
+{
+    // On ARM any references to the pc, adds an additional 8 to it, which
+    // correspond to 2 instructions of 4 bytes.  Thus we use an additional nop
+    // to pad until we reach the pushed pc.
+    //
+    // Note: In practice this should not be necessary, as this fake return
+    // address is never used for resuming any execution. Thus theoriticaly we
+    // could just do a Push(pc), and ignore the nop as well as the pool.
+    enterNoPool(2);
+    DebugOnly<uint32_t> offsetBeforePush = currentOffset();
+    Push(pc); // actually pushes $pc + 8.
+    ma_nop();
+    uint32_t pseudoReturnOffset = currentOffset();
+    leaveNoPool();
+
+    MOZ_ASSERT_IF(!oom(), pseudoReturnOffset - offsetBeforePush == 8);
+    return pseudoReturnOffset;
+}
+
+// ===============================================================
+// Branch functions
+
+void
+MacroAssembler::branchPtrInNurseryChunk(Condition cond, Register ptr, Register temp,
+                                        Label* label)
+{
+    SecondScratchRegisterScope scratch2(*this);
+
+    MOZ_ASSERT(cond == Assembler::Equal || cond == Assembler::NotEqual);
+    MOZ_ASSERT(ptr != temp);
+    MOZ_ASSERT(ptr != scratch2);
+
+    ma_lsr(Imm32(gc::ChunkShift), ptr, scratch2);
+    ma_lsl(Imm32(gc::ChunkShift), scratch2, scratch2);
+    load32(Address(scratch2, gc::ChunkLocationOffset), scratch2);
+    branch32(cond, scratch2, Imm32(int32_t(gc::ChunkLocation::Nursery)), label);
+}
+
+void
+MacroAssembler::branchValueIsNurseryObject(Condition cond, const Address& address,
+                                           Register temp, Label* label)
+{
+    MOZ_ASSERT(cond == Assembler::Equal || cond == Assembler::NotEqual);
+
+    Label done;
+    branchTestObject(Assembler::NotEqual, address, cond == Assembler::Equal ? &done : label);
+
+    loadPtr(address, temp);
+    branchPtrInNurseryChunk(cond, temp, InvalidReg, label);
+
+    bind(&done);
+}
+
+void
+MacroAssembler::branchValueIsNurseryObject(Condition cond, ValueOperand value,
+                                           Register temp, Label* label)
+{
+    MOZ_ASSERT(cond == Assembler::Equal || cond == Assembler::NotEqual);
+
+    Label done;
+    branchTestObject(Assembler::NotEqual, value, cond == Assembler::Equal ? &done : label);
+
+    branchPtrInNurseryChunk(cond, value.payloadReg(), InvalidReg, label);
+
+    bind(&done);
+}
+
+void
+MacroAssembler::branchTestValue(Condition cond, const ValueOperand& lhs,
+                                const Value& rhs, Label* label)
+{
+    MOZ_ASSERT(cond == Equal || cond == NotEqual);
+    // If cond == NotEqual, branch when a.payload != b.payload || a.tag !=
+    // b.tag. If the payloads are equal, compare the tags. If the payloads are
+    // not equal, short circuit true (NotEqual).
+    //
+    // If cand == Equal, branch when a.payload == b.payload && a.tag == b.tag.
+    // If the payloads are equal, compare the tags. If the payloads are not
+    // equal, short circuit false (NotEqual).
+    ScratchRegisterScope scratch(*this);
+
+    if (rhs.isMarkable())
+        ma_cmp(lhs.payloadReg(), ImmGCPtr(rhs.toMarkablePointer()), scratch);
+    else
+        ma_cmp(lhs.payloadReg(), Imm32(rhs.toNunboxPayload()), scratch);
+    ma_cmp(lhs.typeReg(), Imm32(rhs.toNunboxTag()), scratch, Equal);
+    ma_b(label, cond);
+}
+
+// ========================================================================
+// Memory access primitives.
+template <typename T>
+void
+MacroAssembler::storeUnboxedValue(const ConstantOrRegister& value, MIRType valueType,
+                                  const T& dest, MIRType slotType)
+{
+    if (valueType == MIRType::Double) {
+        storeDouble(value.reg().typedReg().fpu(), dest);
+        return;
+    }
+
+    // Store the type tag if needed.
+    if (valueType != slotType)
+        storeTypeTag(ImmType(ValueTypeFromMIRType(valueType)), dest);
+
+    // Store the payload.
+    if (value.constant())
+        storePayload(value.value(), dest);
+    else
+        storePayload(value.reg().typedReg().gpr(), dest);
+}
+
+template void
+MacroAssembler::storeUnboxedValue(const ConstantOrRegister& value, MIRType valueType,
+                                  const Address& dest, MIRType slotType);
+template void
+MacroAssembler::storeUnboxedValue(const ConstantOrRegister& value, MIRType valueType,
+                                  const BaseIndex& dest, MIRType slotType);
+
+void
+MacroAssembler::wasmTruncateDoubleToUInt32(FloatRegister input, Register output, Label* oolEntry)
+{
+    wasmTruncateToInt32(input, output, MIRType::Double, /* isUnsigned= */ true, oolEntry);
+}
+
+void
+MacroAssembler::wasmTruncateDoubleToInt32(FloatRegister input, Register output, Label* oolEntry)
+{
+    wasmTruncateToInt32(input, output, MIRType::Double, /* isUnsigned= */ false, oolEntry);
+}
+
+void
+MacroAssembler::wasmTruncateFloat32ToUInt32(FloatRegister input, Register output, Label* oolEntry)
+{
+    wasmTruncateToInt32(input, output, MIRType::Float32, /* isUnsigned= */ true, oolEntry);
+}
+
+void
+MacroAssembler::wasmTruncateFloat32ToInt32(FloatRegister input, Register output, Label* oolEntry)
+{
+    wasmTruncateToInt32(input, output, MIRType::Float32, /* isUnsigned= */ false, oolEntry);
+}
+
+//}}} check_macroassembler_style
+
+void
+MacroAssemblerARM::wasmTruncateToInt32(FloatRegister input, Register output, MIRType fromType,
+                                       bool isUnsigned, Label* oolEntry)
+{
+    // vcvt* converts NaN into 0, so check for NaNs here.
+    {
+        if (fromType == MIRType::Double)
+            asMasm().compareDouble(input, input);
+        else if (fromType == MIRType::Float32)
+            asMasm().compareFloat(input, input);
+        else
+            MOZ_CRASH("unexpected type in visitWasmTruncateToInt32");
+
+        ma_b(oolEntry, Assembler::VFP_Unordered);
+    }
+
+    ScratchDoubleScope scratchScope(asMasm());
+    ScratchRegisterScope scratchReg(asMasm());
+    FloatRegister scratch = scratchScope.uintOverlay();
+
+    // ARM conversion instructions clamp the value to ensure it fits within the
+    // target's type bounds, so every time we see those, we need to check the
+    // input.
+    if (isUnsigned) {
+        if (fromType == MIRType::Double)
+            ma_vcvt_F64_U32(input, scratch);
+        else if (fromType == MIRType::Float32)
+            ma_vcvt_F32_U32(input, scratch);
+        else
+            MOZ_CRASH("unexpected type in visitWasmTruncateToInt32");
+
+        ma_vxfer(scratch, output);
+
+        // int32_t(UINT32_MAX) == -1.
+        ma_cmp(output, Imm32(-1), scratchReg);
+        as_cmp(output, Imm8(0), Assembler::NotEqual);
+        ma_b(oolEntry, Assembler::Equal);
+
+        return;
+    }
+
+    scratch = scratchScope.sintOverlay();
+
+    if (fromType == MIRType::Double)
+        ma_vcvt_F64_I32(input, scratch);
+    else if (fromType == MIRType::Float32)
+        ma_vcvt_F32_I32(input, scratch);
+    else
+        MOZ_CRASH("unexpected type in visitWasmTruncateToInt32");
+
+    ma_vxfer(scratch, output);
+    ma_cmp(output, Imm32(INT32_MAX), scratchReg);
+    ma_cmp(output, Imm32(INT32_MIN), scratchReg, Assembler::NotEqual);
+    ma_b(oolEntry, Assembler::Equal);
+}
+
+void
+MacroAssemblerARM::outOfLineWasmTruncateToIntCheck(FloatRegister input, MIRType fromType,
+                                                   MIRType toType, bool isUnsigned, Label* rejoin,
+                                                   wasm::TrapOffset trapOffset)
+{
+    ScratchDoubleScope scratchScope(asMasm());
+    FloatRegister scratch;
+
+    // Eagerly take care of NaNs.
+    Label inputIsNaN;
+    if (fromType == MIRType::Double)
+        asMasm().branchDouble(Assembler::DoubleUnordered, input, input, &inputIsNaN);
+    else if (fromType == MIRType::Float32)
+        asMasm().branchFloat(Assembler::DoubleUnordered, input, input, &inputIsNaN);
+    else
+        MOZ_CRASH("unexpected type in visitOutOfLineWasmTruncateCheck");
+
+    // Handle special values.
+    Label fail;
+
+    // By default test for the following inputs and bail:
+    // signed:   ] -Inf, INTXX_MIN - 1.0 ] and [ INTXX_MAX + 1.0 : +Inf [
+    // unsigned: ] -Inf, -1.0 ] and [ UINTXX_MAX + 1.0 : +Inf [
+    // Note: we cannot always represent those exact values. As a result
+    // this changes the actual comparison a bit.
+    double minValue, maxValue;
+    Assembler::DoubleCondition minCond = Assembler::DoubleLessThanOrEqual;
+    Assembler::DoubleCondition maxCond = Assembler::DoubleGreaterThanOrEqual;
+    if (toType == MIRType::Int64) {
+        if (isUnsigned) {
+            minValue = -1;
+            maxValue = double(UINT64_MAX) + 1.0;
+        } else {
+            // In the float32/double range there exists no value between
+            // INT64_MIN and INT64_MIN - 1.0. Making INT64_MIN the lower-bound.
+            minValue = double(INT64_MIN);
+            minCond = Assembler::DoubleLessThan;
+            maxValue = double(INT64_MAX) + 1.0;
+        }
+    } else {
+        if (isUnsigned) {
+            minValue = -1;
+            maxValue = double(UINT32_MAX) + 1.0;
+        } else {
+            if (fromType == MIRType::Float32) {
+                // In the float32 range there exists no value between
+                // INT32_MIN and INT32_MIN - 1.0. Making INT32_MIN the lower-bound.
+                minValue = double(INT32_MIN);
+                minCond = Assembler::DoubleLessThan;
+            } else {
+                minValue = double(INT32_MIN) - 1.0;
+            }
+            maxValue = double(INT32_MAX) + 1.0;
+        }
+    }
+
+    if (fromType == MIRType::Double) {
+        scratch = scratchScope.doubleOverlay();
+        asMasm().loadConstantDouble(minValue, scratch);
+        asMasm().branchDouble(minCond, input, scratch, &fail);
+
+        asMasm().loadConstantDouble(maxValue, scratch);
+        asMasm().branchDouble(maxCond, input, scratch, &fail);
+    } else {
+        MOZ_ASSERT(fromType == MIRType::Float32);
+        scratch = scratchScope.singleOverlay();
+        asMasm().loadConstantFloat32(float(minValue), scratch);
+        asMasm().branchFloat(minCond, input, scratch, &fail);
+
+        asMasm().loadConstantFloat32(float(maxValue), scratch);
+        asMasm().branchFloat(maxCond, input, scratch, &fail);
+    }
+
+    // We had an actual correct value, get back to where we were.
+    ma_b(rejoin);
+
+    // Handle errors.
+    bind(&fail);
+    asMasm().jump(wasm::TrapDesc(trapOffset, wasm::Trap::IntegerOverflow,
+                                 asMasm().framePushed()));
+
+    bind(&inputIsNaN);
+    asMasm().jump(wasm::TrapDesc(trapOffset, wasm::Trap::InvalidConversionToInteger,
+                                 asMasm().framePushed()));
+}
+
+void
+MacroAssemblerARM::emitUnalignedLoad(bool isSigned, unsigned byteSize, Register ptr, Register tmp,
+                                     Register dest, unsigned offset)
+{
+    // Preconditions.
+    MOZ_ASSERT(ptr != tmp);
+    MOZ_ASSERT(ptr != dest);
+    MOZ_ASSERT(tmp != dest);
+    MOZ_ASSERT(byteSize <= 4);
+
+    ScratchRegisterScope scratch(asMasm());
+
+    for (unsigned i = 0; i < byteSize; i++) {
+        // Only the last byte load shall be signed, if needed.
+        bool signedByteLoad = isSigned && (i == byteSize - 1);
+        ma_dataTransferN(IsLoad, 8, signedByteLoad, ptr, Imm32(offset + i), i ? tmp : dest, scratch);
+        if (i)
+            as_orr(dest, dest, lsl(tmp, 8 * i));
+    }
+}
+
+void
+MacroAssemblerARM::emitUnalignedStore(unsigned byteSize, Register ptr, Register val,
+                                      unsigned offset)
+{
+    // Preconditions.
+    MOZ_ASSERT(ptr != val);
+    MOZ_ASSERT(byteSize <= 4);
+
+    ScratchRegisterScope scratch(asMasm());
+
+    for (unsigned i = 0; i < byteSize; i++) {
+        ma_dataTransferN(IsStore, 8 /* bits */, /* signed */ false, ptr, Imm32(offset + i), val, scratch);
+        if (i < byteSize - 1)
+            ma_lsr(Imm32(8), val, val);
+    }
+}
diff --git a/js/src/jit/arm/MacroAssembler-arm.h b/js/src/jit/arm/MacroAssembler-arm.h
new file mode 100644
index 0000000000..c011af3c3b
--- /dev/null
+++ b/js/src/jit/arm/MacroAssembler-arm.h
@@ -0,0 +1,1554 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef jit_arm_MacroAssembler_arm_h
+#define jit_arm_MacroAssembler_arm_h
+
+#include "mozilla/DebugOnly.h"
+
+#include "jsopcode.h"
+
+#include "jit/arm/Assembler-arm.h"
+#include "jit/AtomicOp.h"
+#include "jit/IonCaches.h"
+#include "jit/JitFrames.h"
+#include "jit/MoveResolver.h"
+
+using mozilla::DebugOnly;
+
+namespace js {
+namespace jit {
+
+static Register CallReg = ip;
+static const int defaultShift = 3;
+JS_STATIC_ASSERT(1 << defaultShift == sizeof(JS::Value));
+
+// MacroAssemblerARM is inheriting form Assembler defined in
+// Assembler-arm.{h,cpp}
+class MacroAssemblerARM : public Assembler
+{
+  private:
+    // Perform a downcast. Should be removed by Bug 996602.
+    MacroAssembler& asMasm();
+    const MacroAssembler& asMasm() const;
+
+  protected:
+    // On ARM, some instructions require a second scratch register. This
+    // register defaults to lr, since it's non-allocatable (as it can be
+    // clobbered by some instructions). Allow the baseline compiler to override
+    // this though, since baseline IC stubs rely on lr holding the return
+    // address.
+    Register secondScratchReg_;
+
+  public:
+    Register getSecondScratchReg() const {
+        return secondScratchReg_;
+    }
+
+  public:
+    // Higher level tag testing code.
+    // TODO: Can probably remove the Operand versions.
+    Operand ToPayload(Operand base) const {
+        return Operand(Register::FromCode(base.base()), base.disp());
+    }
+    Address ToPayload(const Address& base) const {
+        return base;
+    }
+
+  protected:
+    Operand ToType(Operand base) const {
+        return Operand(Register::FromCode(base.base()), base.disp() + sizeof(void*));
+    }
+    Address ToType(const Address& base) const {
+        return ToType(Operand(base)).toAddress();
+    }
+
+    Address ToPayloadAfterStackPush(const Address& base) const {
+        // If we are based on StackPointer, pass over the type tag just pushed.
+        if (base.base == StackPointer)
+            return Address(base.base, base.offset + sizeof(void *));
+        return ToPayload(base);
+    }
+
+  public:
+    MacroAssemblerARM()
+      : secondScratchReg_(lr)
+    { }
+
+    void setSecondScratchReg(Register reg) {
+        MOZ_ASSERT(reg != ScratchRegister);
+        secondScratchReg_ = reg;
+    }
+
+    void convertBoolToInt32(Register source, Register dest);
+    void convertInt32ToDouble(Register src, FloatRegister dest);
+    void convertInt32ToDouble(const Address& src, FloatRegister dest);
+    void convertInt32ToDouble(const BaseIndex& src, FloatRegister dest);
+    void convertUInt32ToFloat32(Register src, FloatRegister dest);
+    void convertUInt32ToDouble(Register src, FloatRegister dest);
+    void convertDoubleToFloat32(FloatRegister src, FloatRegister dest,
+                                Condition c = Always);
+    void convertDoubleToInt32(FloatRegister src, Register dest, Label* fail,
+                              bool negativeZeroCheck = true);
+    void convertFloat32ToInt32(FloatRegister src, Register dest, Label* fail,
+                               bool negativeZeroCheck = true);
+
+    void convertFloat32ToDouble(FloatRegister src, FloatRegister dest);
+    void convertInt32ToFloat32(Register src, FloatRegister dest);
+    void convertInt32ToFloat32(const Address& src, FloatRegister dest);
+
+    void wasmTruncateToInt32(FloatRegister input, Register output, MIRType fromType,
+                             bool isUnsigned, Label* oolEntry);
+    void outOfLineWasmTruncateToIntCheck(FloatRegister input, MIRType fromType,
+                                         MIRType toType, bool isUnsigned, Label* rejoin,
+                                         wasm::TrapOffset trapOffs);
+
+    // Somewhat direct wrappers for the low-level assembler funcitons
+    // bitops. Attempt to encode a virtual alu instruction using two real
+    // instructions.
+  private:
+    bool alu_dbl(Register src1, Imm32 imm, Register dest, ALUOp op,
+                 SBit s, Condition c);
+
+  public:
+    void ma_alu(Register src1, Imm32 imm, Register dest, AutoRegisterScope& scratch,
+                ALUOp op, SBit s = LeaveCC, Condition c = Always);
+    void ma_alu(Register src1, Operand2 op2, Register dest, ALUOp op,
+                SBit s = LeaveCC, Condition c = Always);
+    void ma_alu(Register src1, Operand op2, Register dest, ALUOp op,
+                SBit s = LeaveCC, Condition c = Always);
+    void ma_nop();
+
+    void ma_movPatchable(Imm32 imm, Register dest, Assembler::Condition c);
+    void ma_movPatchable(ImmPtr imm, Register dest, Assembler::Condition c);
+
+    static void ma_mov_patch(Imm32 imm, Register dest, Assembler::Condition c,
+                             RelocStyle rs, Instruction* i);
+    static void ma_mov_patch(ImmPtr imm, Register dest, Assembler::Condition c,
+                             RelocStyle rs, Instruction* i);
+
+    // ALU based ops
+    // mov
+    void ma_mov(Register src, Register dest, SBit s = LeaveCC, Condition c = Always);
+
+    void ma_mov(Imm32 imm, Register dest, Condition c = Always);
+    void ma_mov(ImmWord imm, Register dest, Condition c = Always);
+
+    void ma_mov(ImmGCPtr ptr, Register dest);
+
+    // Shifts (just a move with a shifting op2)
+    void ma_lsl(Imm32 shift, Register src, Register dst);
+    void ma_lsr(Imm32 shift, Register src, Register dst);
+    void ma_asr(Imm32 shift, Register src, Register dst);
+    void ma_ror(Imm32 shift, Register src, Register dst);
+    void ma_rol(Imm32 shift, Register src, Register dst);
+
+    void ma_lsl(Register shift, Register src, Register dst);
+    void ma_lsr(Register shift, Register src, Register dst);
+    void ma_asr(Register shift, Register src, Register dst);
+    void ma_ror(Register shift, Register src, Register dst);
+    void ma_rol(Register shift, Register src, Register dst, AutoRegisterScope& scratch);
+
+    // Move not (dest <- ~src)
+    void ma_mvn(Register src1, Register dest, SBit s = LeaveCC, Condition c = Always);
+
+    // Negate (dest <- -src) implemented as rsb dest, src, 0
+    void ma_neg(Register src, Register dest,
+                SBit s = LeaveCC, Condition c = Always);
+
+    // And
+    void ma_and(Register src, Register dest,
+                SBit s = LeaveCC, Condition c = Always);
+
+    void ma_and(Register src1, Register src2, Register dest,
+                SBit s = LeaveCC, Condition c = Always);
+
+    void ma_and(Imm32 imm, Register dest, AutoRegisterScope& scratch,
+                SBit s = LeaveCC, Condition c = Always);
+
+    void ma_and(Imm32 imm, Register src1, Register dest, AutoRegisterScope& scratch,
+                SBit s = LeaveCC, Condition c = Always);
+
+    // Bit clear (dest <- dest & ~imm) or (dest <- src1 & ~src2)
+    void ma_bic(Imm32 imm, Register dest, AutoRegisterScope& scratch,
+                SBit s = LeaveCC, Condition c = Always);
+
+    // Exclusive or
+    void ma_eor(Register src, Register dest,
+                SBit s = LeaveCC, Condition c = Always);
+
+    void ma_eor(Register src1, Register src2, Register dest,
+                SBit s = LeaveCC, Condition c = Always);
+
+    void ma_eor(Imm32 imm, Register dest, AutoRegisterScope& scratch,
+                SBit s = LeaveCC, Condition c = Always);
+
+    void ma_eor(Imm32 imm, Register src1, Register dest, AutoRegisterScope& scratch,
+                SBit s = LeaveCC, Condition c = Always);
+
+    // Or
+    void ma_orr(Register src, Register dest,
+                SBit s = LeaveCC, Condition c = Always);
+
+    void ma_orr(Register src1, Register src2, Register dest,
+                SBit s = LeaveCC, Condition c = Always);
+
+    void ma_orr(Imm32 imm, Register dest, AutoRegisterScope& scratch,
+                SBit s = LeaveCC, Condition c = Always);
+
+    void ma_orr(Imm32 imm, Register src1, Register dest, AutoRegisterScope& scratch,
+                SBit s = LeaveCC, Condition c = Always);
+
+
+    // Arithmetic based ops.
+    // Add with carry:
+    void ma_adc(Imm32 imm, Register dest, AutoRegisterScope& scratch, SBit s = LeaveCC, Condition c = Always);
+    void ma_adc(Register src, Register dest, SBit s = LeaveCC, Condition c = Always);
+    void ma_adc(Register src1, Register src2, Register dest, SBit s = LeaveCC, Condition c = Always);
+
+    // Add:
+    void ma_add(Imm32 imm, Register dest, AutoRegisterScope& scratch, SBit s = LeaveCC, Condition c = Always);
+    void ma_add(Register src1, Register dest, SBit s = LeaveCC, Condition c = Always);
+    void ma_add(Register src1, Register src2, Register dest, SBit s = LeaveCC, Condition c = Always);
+    void ma_add(Register src1, Operand op, Register dest, SBit s = LeaveCC, Condition c = Always);
+    void ma_add(Register src1, Imm32 op, Register dest, AutoRegisterScope& scratch,
+                SBit s = LeaveCC, Condition c = Always);
+
+    // Subtract with carry:
+    void ma_sbc(Imm32 imm, Register dest, AutoRegisterScope& scratch, SBit s = LeaveCC, Condition c = Always);
+    void ma_sbc(Register src1, Register dest, SBit s = LeaveCC, Condition c = Always);
+    void ma_sbc(Register src1, Register src2, Register dest, SBit s = LeaveCC, Condition c = Always);
+
+    // Subtract:
+    void ma_sub(Imm32 imm, Register dest, AutoRegisterScope& scratch, SBit s = LeaveCC, Condition c = Always);
+    void ma_sub(Register src1, Register dest, SBit s = LeaveCC, Condition c = Always);
+    void ma_sub(Register src1, Register src2, Register dest, SBit s = LeaveCC, Condition c = Always);
+    void ma_sub(Register src1, Operand op, Register dest, SBit s = LeaveCC, Condition c = Always);
+    void ma_sub(Register src1, Imm32 op, Register dest, AutoRegisterScope& scratch,
+                SBit s = LeaveCC, Condition c = Always);
+
+    // Reverse subtract:
+    void ma_rsb(Imm32 imm, Register dest, AutoRegisterScope& scratch, SBit s = LeaveCC, Condition c = Always);
+    void ma_rsb(Register src1, Register dest, SBit s = LeaveCC, Condition c = Always);
+    void ma_rsb(Register src1, Register src2, Register dest, SBit s = LeaveCC, Condition c = Always);
+    void ma_rsb(Register src1, Imm32 op2, Register dest, AutoRegisterScope& scratch,
+                SBit s = LeaveCC, Condition c = Always);
+
+    // Reverse subtract with carry:
+    void ma_rsc(Imm32 imm, Register dest, AutoRegisterScope& scratch, SBit s = LeaveCC, Condition c = Always);
+    void ma_rsc(Register src1, Register dest, SBit s = LeaveCC, Condition c = Always);
+    void ma_rsc(Register src1, Register src2, Register dest, SBit s = LeaveCC, Condition c = Always);
+
+    // Compares/tests.
+    // Compare negative (sets condition codes as src1 + src2 would):
+    void ma_cmn(Register src1, Imm32 imm, AutoRegisterScope& scratch, Condition c = Always);
+    void ma_cmn(Register src1, Register src2, Condition c = Always);
+    void ma_cmn(Register src1, Operand op, Condition c = Always);
+
+    // Compare (src - src2):
+    void ma_cmp(Register src1, Imm32 imm, AutoRegisterScope& scratch, Condition c = Always);
+    void ma_cmp(Register src1, ImmTag tag, Condition c = Always);
+    void ma_cmp(Register src1, ImmWord ptr, AutoRegisterScope& scratch, Condition c = Always);
+    void ma_cmp(Register src1, ImmGCPtr ptr, AutoRegisterScope& scratch, Condition c = Always);
+    void ma_cmp(Register src1, Operand op, AutoRegisterScope& scratch, AutoRegisterScope& scratch2,
+                Condition c = Always);
+    void ma_cmp(Register src1, Register src2, Condition c = Always);
+
+    // Test for equality, (src1 ^ src2):
+    void ma_teq(Register src1, Imm32 imm, AutoRegisterScope& scratch, Condition c = Always);
+    void ma_teq(Register src1, Register src2, Condition c = Always);
+    void ma_teq(Register src1, Operand op, Condition c = Always);
+
+    // Test (src1 & src2):
+    void ma_tst(Register src1, Imm32 imm, AutoRegisterScope& scratch, Condition c = Always);
+    void ma_tst(Register src1, Register src2, Condition c = Always);
+    void ma_tst(Register src1, Operand op, Condition c = Always);
+
+    // Multiplies. For now, there are only two that we care about.
+    void ma_mul(Register src1, Register src2, Register dest);
+    void ma_mul(Register src1, Imm32 imm, Register dest, AutoRegisterScope& scratch);
+    Condition ma_check_mul(Register src1, Register src2, Register dest,
+                           AutoRegisterScope& scratch, Condition cond);
+    Condition ma_check_mul(Register src1, Imm32 imm, Register dest,
+                           AutoRegisterScope& scratch, Condition cond);
+
+    void ma_umull(Register src1, Imm32 imm, Register destHigh, Register destLow, AutoRegisterScope& scratch);
+    void ma_umull(Register src1, Register src2, Register destHigh, Register destLow);
+
+    // Fast mod, uses scratch registers, and thus needs to be in the assembler
+    // implicitly assumes that we can overwrite dest at the beginning of the
+    // sequence.
+    void ma_mod_mask(Register src, Register dest, Register hold, Register tmp,
+                     AutoRegisterScope& scratch, AutoRegisterScope& scratch2, int32_t shift);
+
+    // Mod - depends on integer divide instructions being supported.
+    void ma_smod(Register num, Register div, Register dest, AutoRegisterScope& scratch);
+    void ma_umod(Register num, Register div, Register dest, AutoRegisterScope& scratch);
+
+    // Division - depends on integer divide instructions being supported.
+    void ma_sdiv(Register num, Register div, Register dest, Condition cond = Always);
+    void ma_udiv(Register num, Register div, Register dest, Condition cond = Always);
+    // Misc operations
+    void ma_clz(Register src, Register dest, Condition cond = Always);
+    void ma_ctz(Register src, Register dest, AutoRegisterScope& scratch);
+    // Memory:
+    // Shortcut for when we know we're transferring 32 bits of data.
+    void ma_dtr(LoadStore ls, Register rn, Imm32 offset, Register rt, AutoRegisterScope& scratch,
+                Index mode = Offset, Condition cc = Always);
+    void ma_dtr(LoadStore ls, Register rt, const Address& addr, AutoRegisterScope& scratch,
+                Index mode, Condition cc);
+
+    void ma_str(Register rt, DTRAddr addr, Index mode = Offset, Condition cc = Always);
+    void ma_str(Register rt, const Address& addr, AutoRegisterScope& scratch,
+                Index mode = Offset, Condition cc = Always);
+
+    void ma_ldr(DTRAddr addr, Register rt, Index mode = Offset, Condition cc = Always);
+    void ma_ldr(const Address& addr, Register rt, AutoRegisterScope& scratch,
+                Index mode = Offset, Condition cc = Always);
+
+    void ma_ldrb(DTRAddr addr, Register rt, Index mode = Offset, Condition cc = Always);
+    void ma_ldrh(EDtrAddr addr, Register rt, Index mode = Offset, Condition cc = Always);
+    void ma_ldrsh(EDtrAddr addr, Register rt, Index mode = Offset, Condition cc = Always);
+    void ma_ldrsb(EDtrAddr addr, Register rt, Index mode = Offset, Condition cc = Always);
+    void ma_ldrd(EDtrAddr addr, Register rt, DebugOnly<Register> rt2, Index mode = Offset,
+                 Condition cc = Always);
+    void ma_strb(Register rt, DTRAddr addr, Index mode = Offset, Condition cc = Always);
+    void ma_strh(Register rt, EDtrAddr addr, Index mode = Offset, Condition cc = Always);
+    void ma_strd(Register rt, DebugOnly<Register> rt2, EDtrAddr addr, Index mode = Offset,
+                 Condition cc = Always);
+
+    // Specialty for moving N bits of data, where n == 8,16,32,64.
+    BufferOffset ma_dataTransferN(LoadStore ls, int size, bool IsSigned,
+                                  Register rn, Register rm, Register rt, AutoRegisterScope& scratch,
+                                  Index mode = Offset, Condition cc = Always,
+                                  Scale scale = TimesOne);
+
+    BufferOffset ma_dataTransferN(LoadStore ls, int size, bool IsSigned,
+                                  Register rn, Register rm, Register rt,
+                                  Index mode = Offset, Condition cc = Always);
+
+    BufferOffset ma_dataTransferN(LoadStore ls, int size, bool IsSigned,
+                                  Register rn, Imm32 offset, Register rt, AutoRegisterScope& scratch,
+                                  Index mode = Offset, Condition cc = Always);
+
+    void ma_pop(Register r);
+    void ma_popn_pc(Imm32 n, AutoRegisterScope& scratch, AutoRegisterScope& scratch2);
+    void ma_push(Register r);
+    void ma_push_sp(Register r, AutoRegisterScope& scratch);
+
+    void ma_vpop(VFPRegister r);
+    void ma_vpush(VFPRegister r);
+
+    // Barriers.
+    void ma_dmb(BarrierOption option=BarrierSY);
+    void ma_dsb(BarrierOption option=BarrierSY);
+
+    // Branches when done from within arm-specific code.
+    BufferOffset ma_b(Label* dest, Condition c = Always);
+    BufferOffset ma_b(wasm::TrapDesc target, Condition c = Always);
+    void ma_b(void* target, Condition c = Always);
+    void ma_bx(Register dest, Condition c = Always);
+
+    // This is almost NEVER necessary, we'll basically never be calling a label
+    // except, possibly in the crazy bailout-table case.
+    void ma_bl(Label* dest, Condition c = Always);
+
+    void ma_blx(Register dest, Condition c = Always);
+
+    // VFP/ALU:
+    void ma_vadd(FloatRegister src1, FloatRegister src2, FloatRegister dst);
+    void ma_vsub(FloatRegister src1, FloatRegister src2, FloatRegister dst);
+
+    void ma_vmul(FloatRegister src1, FloatRegister src2, FloatRegister dst);
+    void ma_vdiv(FloatRegister src1, FloatRegister src2, FloatRegister dst);
+
+    void ma_vneg(FloatRegister src, FloatRegister dest, Condition cc = Always);
+    void ma_vmov(FloatRegister src, FloatRegister dest, Condition cc = Always);
+    void ma_vmov_f32(FloatRegister src, FloatRegister dest, Condition cc = Always);
+    void ma_vabs(FloatRegister src, FloatRegister dest, Condition cc = Always);
+    void ma_vabs_f32(FloatRegister src, FloatRegister dest, Condition cc = Always);
+
+    void ma_vsqrt(FloatRegister src, FloatRegister dest, Condition cc = Always);
+    void ma_vsqrt_f32(FloatRegister src, FloatRegister dest, Condition cc = Always);
+
+    void ma_vimm(wasm::RawF64 value, FloatRegister dest, Condition cc = Always);
+    void ma_vimm_f32(wasm::RawF32 value, FloatRegister dest, Condition cc = Always);
+
+    void ma_vcmp(FloatRegister src1, FloatRegister src2, Condition cc = Always);
+    void ma_vcmp_f32(FloatRegister src1, FloatRegister src2, Condition cc = Always);
+    void ma_vcmpz(FloatRegister src1, Condition cc = Always);
+    void ma_vcmpz_f32(FloatRegister src1, Condition cc = Always);
+
+    void ma_vadd_f32(FloatRegister src1, FloatRegister src2, FloatRegister dst);
+    void ma_vsub_f32(FloatRegister src1, FloatRegister src2, FloatRegister dst);
+
+    void ma_vmul_f32(FloatRegister src1, FloatRegister src2, FloatRegister dst);
+    void ma_vdiv_f32(FloatRegister src1, FloatRegister src2, FloatRegister dst);
+
+    void ma_vneg_f32(FloatRegister src, FloatRegister dest, Condition cc = Always);
+
+    // Source is F64, dest is I32:
+    void ma_vcvt_F64_I32(FloatRegister src, FloatRegister dest, Condition cc = Always);
+    void ma_vcvt_F64_U32(FloatRegister src, FloatRegister dest, Condition cc = Always);
+
+    // Source is I32, dest is F64:
+    void ma_vcvt_I32_F64(FloatRegister src, FloatRegister dest, Condition cc = Always);
+    void ma_vcvt_U32_F64(FloatRegister src, FloatRegister dest, Condition cc = Always);
+
+    // Source is F32, dest is I32:
+    void ma_vcvt_F32_I32(FloatRegister src, FloatRegister dest, Condition cc = Always);
+    void ma_vcvt_F32_U32(FloatRegister src, FloatRegister dest, Condition cc = Always);
+
+    // Source is I32, dest is F32:
+    void ma_vcvt_I32_F32(FloatRegister src, FloatRegister dest, Condition cc = Always);
+    void ma_vcvt_U32_F32(FloatRegister src, FloatRegister dest, Condition cc = Always);
+
+
+    // Transfer (do not coerce) a float into a gpr.
+    void ma_vxfer(VFPRegister src, Register dest, Condition cc = Always);
+    // Transfer (do not coerce) a double into a couple of gpr.
+    void ma_vxfer(VFPRegister src, Register dest1, Register dest2, Condition cc = Always);
+
+    // Transfer (do not coerce) a gpr into a float
+    void ma_vxfer(Register src, FloatRegister dest, Condition cc = Always);
+    // Transfer (do not coerce) a couple of gpr into a double
+    void ma_vxfer(Register src1, Register src2, FloatRegister dest, Condition cc = Always);
+
+    BufferOffset ma_vdtr(LoadStore ls, const Address& addr, VFPRegister dest, AutoRegisterScope& scratch,
+                         Condition cc = Always);
+
+    BufferOffset ma_vldr(VFPAddr addr, VFPRegister dest, Condition cc = Always);
+    BufferOffset ma_vldr(const Address& addr, VFPRegister dest, AutoRegisterScope& scratch, Condition cc = Always);
+    BufferOffset ma_vldr(VFPRegister src, Register base, Register index, AutoRegisterScope& scratch,
+                         int32_t shift = defaultShift, Condition cc = Always);
+
+    BufferOffset ma_vstr(VFPRegister src, VFPAddr addr, Condition cc = Always);
+    BufferOffset ma_vstr(VFPRegister src, const Address& addr, AutoRegisterScope& scratch, Condition cc = Always);
+    BufferOffset ma_vstr(VFPRegister src, Register base, Register index, AutoRegisterScope& scratch,
+                         AutoRegisterScope& scratch2, int32_t shift, int32_t offset, Condition cc = Always);
+    BufferOffset ma_vstr(VFPRegister src, Register base, Register index, AutoRegisterScope& scratch,
+                         int32_t shift, Condition cc = Always);
+
+    void ma_call(ImmPtr dest);
+
+    // Float registers can only be loaded/stored in continuous runs when using
+    // vstm/vldm. This function breaks set into continuous runs and loads/stores
+    // them at [rm]. rm will be modified and left in a state logically suitable
+    // for the next load/store. Returns the offset from [dm] for the logical
+    // next load/store.
+    int32_t transferMultipleByRuns(FloatRegisterSet set, LoadStore ls,
+                                   Register rm, DTMMode mode)
+    {
+        if (mode == IA) {
+            return transferMultipleByRunsImpl
+                <FloatRegisterForwardIterator>(set, ls, rm, mode, 1);
+        }
+        if (mode == DB) {
+            return transferMultipleByRunsImpl
+                <FloatRegisterBackwardIterator>(set, ls, rm, mode, -1);
+        }
+        MOZ_CRASH("Invalid data transfer addressing mode");
+    }
+
+    // Loads `byteSize` bytes, byte by byte, by reading from ptr[offset],
+    // applying the indicated signedness (defined by isSigned).
+    // - all three registers must be different.
+    // - tmp and dest will get clobbered, ptr will remain intact.
+    // - byteSize can be up to 4 bytes and no more (GPR are 32 bits on ARM).
+    void emitUnalignedLoad(bool isSigned, unsigned byteSize, Register ptr, Register tmp,
+                           Register dest, unsigned offset = 0);
+
+    // Ditto, for a store. Note stores don't care about signedness.
+    // - the two registers must be different.
+    // - val will get clobbered, ptr will remain intact.
+    // - byteSize can be up to 4 bytes and no more (GPR are 32 bits on ARM).
+    void emitUnalignedStore(unsigned byteSize, Register ptr, Register val, unsigned offset = 0);
+
+private:
+    // Implementation for transferMultipleByRuns so we can use different
+    // iterators for forward/backward traversals. The sign argument should be 1
+    // if we traverse forwards, -1 if we traverse backwards.
+    template<typename RegisterIterator> int32_t
+    transferMultipleByRunsImpl(FloatRegisterSet set, LoadStore ls,
+                               Register rm, DTMMode mode, int32_t sign)
+    {
+        MOZ_ASSERT(sign == 1 || sign == -1);
+
+        int32_t delta = sign * sizeof(float);
+        int32_t offset = 0;
+        // Build up a new set, which is the sum of all of the single and double
+        // registers. This set can have up to 48 registers in it total
+        // s0-s31 and d16-d31
+        FloatRegisterSet mod = set.reduceSetForPush();
+
+        RegisterIterator iter(mod);
+        while (iter.more()) {
+            startFloatTransferM(ls, rm, mode, WriteBack);
+            int32_t reg = (*iter).code();
+            do {
+                offset += delta;
+                if ((*iter).isDouble())
+                    offset += delta;
+                transferFloatReg(*iter);
+            } while ((++iter).more() && int32_t((*iter).code()) == (reg += sign));
+            finishFloatTransfer();
+        }
+        return offset;
+    }
+};
+
+class MacroAssembler;
+
+class MacroAssemblerARMCompat : public MacroAssemblerARM
+{
+  private:
+    // Perform a downcast. Should be removed by Bug 996602.
+    MacroAssembler& asMasm();
+    const MacroAssembler& asMasm() const;
+
+  public:
+    MacroAssemblerARMCompat()
+    { }
+
+  public:
+
+    // Jumps + other functions that should be called from non-arm specific
+    // code. Basically, an x86 front end on top of the ARM code.
+    void j(Condition code , Label* dest)
+    {
+        as_b(dest, code);
+    }
+    void j(Label* dest)
+    {
+        as_b(dest, Always);
+    }
+
+    void mov(Register src, Register dest) {
+        ma_mov(src, dest);
+    }
+    void mov(ImmWord imm, Register dest) {
+        ma_mov(Imm32(imm.value), dest);
+    }
+    void mov(ImmPtr imm, Register dest) {
+        mov(ImmWord(uintptr_t(imm.value)), dest);
+    }
+    void mov(Register src, Address dest) {
+        MOZ_CRASH("NYI-IC");
+    }
+    void mov(Address src, Register dest) {
+        MOZ_CRASH("NYI-IC");
+    }
+
+    void branch(JitCode* c) {
+        BufferOffset bo = m_buffer.nextOffset();
+        addPendingJump(bo, ImmPtr(c->raw()), Relocation::JITCODE);
+        ScratchRegisterScope scratch(asMasm());
+        ma_movPatchable(ImmPtr(c->raw()), scratch, Always);
+        ma_bx(scratch);
+    }
+    void branch(const Register reg) {
+        ma_bx(reg);
+    }
+    void nop() {
+        ma_nop();
+    }
+    void shortJumpSizedNop() {
+        ma_nop();
+    }
+    void ret() {
+        ma_pop(pc);
+    }
+    void retn(Imm32 n) {
+        ScratchRegisterScope scratch(asMasm());
+        SecondScratchRegisterScope scratch2(asMasm());
+        ma_popn_pc(n, scratch, scratch2);
+    }
+    void push(Imm32 imm) {
+        ScratchRegisterScope scratch(asMasm());
+        ma_mov(imm, scratch);
+        ma_push(scratch);
+    }
+    void push(ImmWord imm) {
+        push(Imm32(imm.value));
+    }
+    void push(ImmGCPtr imm) {
+        ScratchRegisterScope scratch(asMasm());
+        ma_mov(imm, scratch);
+        ma_push(scratch);
+    }
+    void push(const Address& addr) {
+        ScratchRegisterScope scratch(asMasm());
+        SecondScratchRegisterScope scratch2(asMasm());
+        ma_ldr(addr, scratch, scratch2);
+        ma_push(scratch);
+    }
+    void push(Register reg) {
+        if (reg == sp) {
+            ScratchRegisterScope scratch(asMasm());
+            ma_push_sp(reg, scratch);
+        } else {
+            ma_push(reg);
+        }
+    }
+    void push(FloatRegister reg) {
+        ma_vpush(VFPRegister(reg));
+    }
+    void pushWithPadding(Register reg, const Imm32 extraSpace) {
+        ScratchRegisterScope scratch(asMasm());
+        Imm32 totSpace = Imm32(extraSpace.value + 4);
+        ma_dtr(IsStore, sp, totSpace, reg, scratch, PreIndex);
+    }
+    void pushWithPadding(Imm32 imm, const Imm32 extraSpace) {
+        ScratchRegisterScope scratch(asMasm());
+        SecondScratchRegisterScope scratch2(asMasm());
+        Imm32 totSpace = Imm32(extraSpace.value + 4);
+        ma_mov(imm, scratch);
+        ma_dtr(IsStore, sp, totSpace, scratch, scratch2, PreIndex);
+    }
+
+    void pop(Register reg) {
+        ma_pop(reg);
+    }
+    void pop(FloatRegister reg) {
+        ma_vpop(VFPRegister(reg));
+    }
+
+    void popN(Register reg, Imm32 extraSpace) {
+        ScratchRegisterScope scratch(asMasm());
+        Imm32 totSpace = Imm32(extraSpace.value + 4);
+        ma_dtr(IsLoad, sp, totSpace, reg, scratch, PostIndex);
+    }
+
+    CodeOffset toggledJump(Label* label);
+
+    // Emit a BLX or NOP instruction. ToggleCall can be used to patch this
+    // instruction.
+    CodeOffset toggledCall(JitCode* target, bool enabled);
+
+    CodeOffset pushWithPatch(ImmWord imm) {
+        ScratchRegisterScope scratch(asMasm());
+        CodeOffset label = movWithPatch(imm, scratch);
+        ma_push(scratch);
+        return label;
+    }
+
+    CodeOffset movWithPatch(ImmWord imm, Register dest) {
+        CodeOffset label = CodeOffset(currentOffset());
+        ma_movPatchable(Imm32(imm.value), dest, Always);
+        return label;
+    }
+    CodeOffset movWithPatch(ImmPtr imm, Register dest) {
+        return movWithPatch(ImmWord(uintptr_t(imm.value)), dest);
+    }
+
+    void jump(Label* label) {
+        as_b(label);
+    }
+    void jump(JitCode* code) {
+        branch(code);
+    }
+    void jump(Register reg) {
+        ma_bx(reg);
+    }
+    void jump(const Address& addr) {
+        ScratchRegisterScope scratch(asMasm());
+        SecondScratchRegisterScope scratch2(asMasm());
+        ma_ldr(addr, scratch, scratch2);
+        ma_bx(scratch);
+    }
+    void jump(wasm::TrapDesc target) {
+        as_b(target);
+    }
+
+    void negl(Register reg) {
+        ma_neg(reg, reg, SetCC);
+    }
+    void test32(Register lhs, Register rhs) {
+        ma_tst(lhs, rhs);
+    }
+    void test32(Register lhs, Imm32 imm) {
+        ScratchRegisterScope scratch(asMasm());
+        ma_tst(lhs, imm, scratch);
+    }
+    void test32(const Address& addr, Imm32 imm) {
+        ScratchRegisterScope scratch(asMasm());
+        SecondScratchRegisterScope scratch2(asMasm());
+        ma_ldr(addr, scratch, scratch2);
+        ma_tst(scratch, imm, scratch2);
+    }
+    void testPtr(Register lhs, Register rhs) {
+        test32(lhs, rhs);
+    }
+
+    // Returns the register containing the type tag.
+    Register splitTagForTest(const ValueOperand& value) {
+        return value.typeReg();
+    }
+
+    // Higher level tag testing code.
+    Condition testInt32(Condition cond, const ValueOperand& value);
+    Condition testBoolean(Condition cond, const ValueOperand& value);
+    Condition testDouble(Condition cond, const ValueOperand& value);
+    Condition testNull(Condition cond, const ValueOperand& value);
+    Condition testUndefined(Condition cond, const ValueOperand& value);
+    Condition testString(Condition cond, const ValueOperand& value);
+    Condition testSymbol(Condition cond, const ValueOperand& value);
+    Condition testObject(Condition cond, const ValueOperand& value);
+    Condition testNumber(Condition cond, const ValueOperand& value);
+    Condition testMagic(Condition cond, const ValueOperand& value);
+
+    Condition testPrimitive(Condition cond, const ValueOperand& value);
+
+    // Register-based tests.
+    Condition testInt32(Condition cond, Register tag);
+    Condition testBoolean(Condition cond, Register tag);
+    Condition testNull(Condition cond, Register tag);
+    Condition testUndefined(Condition cond, Register tag);
+    Condition testString(Condition cond, Register tag);
+    Condition testSymbol(Condition cond, Register tag);
+    Condition testObject(Condition cond, Register tag);
+    Condition testDouble(Condition cond, Register tag);
+    Condition testNumber(Condition cond, Register tag);
+    Condition testMagic(Condition cond, Register tag);
+    Condition testPrimitive(Condition cond, Register tag);
+
+    Condition testGCThing(Condition cond, const Address& address);
+    Condition testMagic(Condition cond, const Address& address);
+    Condition testInt32(Condition cond, const Address& address);
+    Condition testDouble(Condition cond, const Address& address);
+    Condition testBoolean(Condition cond, const Address& address);
+    Condition testNull(Condition cond, const Address& address);
+    Condition testUndefined(Condition cond, const Address& address);
+    Condition testString(Condition cond, const Address& address);
+    Condition testSymbol(Condition cond, const Address& address);
+    Condition testObject(Condition cond, const Address& address);
+    Condition testNumber(Condition cond, const Address& address);
+
+    Condition testUndefined(Condition cond, const BaseIndex& src);
+    Condition testNull(Condition cond, const BaseIndex& src);
+    Condition testBoolean(Condition cond, const BaseIndex& src);
+    Condition testString(Condition cond, const BaseIndex& src);
+    Condition testSymbol(Condition cond, const BaseIndex& src);
+    Condition testInt32(Condition cond, const BaseIndex& src);
+    Condition testObject(Condition cond, const BaseIndex& src);
+    Condition testDouble(Condition cond, const BaseIndex& src);
+    Condition testMagic(Condition cond, const BaseIndex& src);
+    Condition testGCThing(Condition cond, const BaseIndex& src);
+
+    // Unboxing code.
+    void unboxNonDouble(const ValueOperand& operand, Register dest);
+    void unboxNonDouble(const Address& src, Register dest);
+    void unboxNonDouble(const BaseIndex& src, Register dest);
+    void unboxInt32(const ValueOperand& src, Register dest) { unboxNonDouble(src, dest); }
+    void unboxInt32(const Address& src, Register dest) { unboxNonDouble(src, dest); }
+    void unboxBoolean(const ValueOperand& src, Register dest) { unboxNonDouble(src, dest); }
+    void unboxBoolean(const Address& src, Register dest) { unboxNonDouble(src, dest); }
+    void unboxString(const ValueOperand& src, Register dest) { unboxNonDouble(src, dest); }
+    void unboxString(const Address& src, Register dest) { unboxNonDouble(src, dest); }
+    void unboxSymbol(const ValueOperand& src, Register dest) { unboxNonDouble(src, dest); }
+    void unboxSymbol(const Address& src, Register dest) { unboxNonDouble(src, dest); }
+    void unboxObject(const ValueOperand& src, Register dest) { unboxNonDouble(src, dest); }
+    void unboxObject(const Address& src, Register dest) { unboxNonDouble(src, dest); }
+    void unboxObject(const BaseIndex& src, Register dest) { unboxNonDouble(src, dest); }
+    void unboxDouble(const ValueOperand& src, FloatRegister dest);
+    void unboxDouble(const Address& src, FloatRegister dest);
+    void unboxValue(const ValueOperand& src, AnyRegister dest);
+    void unboxPrivate(const ValueOperand& src, Register dest);
+
+    void notBoolean(const ValueOperand& val) {
+        as_eor(val.payloadReg(), val.payloadReg(), Imm8(1));
+    }
+
+    // Boxing code.
+    void boxDouble(FloatRegister src, const ValueOperand& dest);
+    void boxNonDouble(JSValueType type, Register src, const ValueOperand& dest);
+
+    // Extended unboxing API. If the payload is already in a register, returns
+    // that register. Otherwise, provides a move to the given scratch register,
+    // and returns that.
+    Register extractObject(const Address& address, Register scratch);
+    Register extractObject(const ValueOperand& value, Register scratch) {
+        return value.payloadReg();
+    }
+    Register extractInt32(const ValueOperand& value, Register scratch) {
+        return value.payloadReg();
+    }
+    Register extractBoolean(const ValueOperand& value, Register scratch) {
+        return value.payloadReg();
+    }
+    Register extractTag(const Address& address, Register scratch);
+    Register extractTag(const BaseIndex& address, Register scratch);
+    Register extractTag(const ValueOperand& value, Register scratch) {
+        return value.typeReg();
+    }
+
+    void boolValueToDouble(const ValueOperand& operand, FloatRegister dest);
+    void int32ValueToDouble(const ValueOperand& operand, FloatRegister dest);
+    void loadInt32OrDouble(const Address& src, FloatRegister dest);
+    void loadInt32OrDouble(Register base, Register index,
+                           FloatRegister dest, int32_t shift = defaultShift);
+    void loadConstantDouble(double dp, FloatRegister dest);
+    void loadConstantDouble(wasm::RawF64 dp, FloatRegister dest);
+
+    // Treat the value as a boolean, and set condition codes accordingly.
+    Condition testInt32Truthy(bool truthy, const ValueOperand& operand);
+    Condition testBooleanTruthy(bool truthy, const ValueOperand& operand);
+    Condition testDoubleTruthy(bool truthy, FloatRegister reg);
+    Condition testStringTruthy(bool truthy, const ValueOperand& value);
+
+    void boolValueToFloat32(const ValueOperand& operand, FloatRegister dest);
+    void int32ValueToFloat32(const ValueOperand& operand, FloatRegister dest);
+    void loadConstantFloat32(float f, FloatRegister dest);
+    void loadConstantFloat32(wasm::RawF32 f, FloatRegister dest);
+
+    void moveValue(const Value& val, Register type, Register data);
+
+    CodeOffsetJump jumpWithPatch(RepatchLabel* label, Condition cond = Always,
+                                 Label* documentation = nullptr);
+    CodeOffsetJump backedgeJump(RepatchLabel* label, Label* documentation) {
+        return jumpWithPatch(label, Always, documentation);
+    }
+
+    void loadUnboxedValue(Address address, MIRType type, AnyRegister dest) {
+        if (dest.isFloat()) {
+            loadInt32OrDouble(address, dest.fpu());
+        } else {
+            ScratchRegisterScope scratch(asMasm());
+            ma_ldr(address, dest.gpr(), scratch);
+        }
+    }
+
+    void loadUnboxedValue(BaseIndex address, MIRType type, AnyRegister dest) {
+        if (dest.isFloat())
+            loadInt32OrDouble(address.base, address.index, dest.fpu(), address.scale);
+        else
+            load32(address, dest.gpr());
+    }
+
+    template <typename T>
+    void storeUnboxedPayload(ValueOperand value, T address, size_t nbytes) {
+        switch (nbytes) {
+          case 4:
+            storePtr(value.payloadReg(), address);
+            return;
+          case 1:
+            store8(value.payloadReg(), address);
+            return;
+          default: MOZ_CRASH("Bad payload width");
+        }
+    }
+
+    void moveValue(const Value& val, const ValueOperand& dest);
+
+    void moveValue(const ValueOperand& src, const ValueOperand& dest) {
+        Register s0 = src.typeReg(), d0 = dest.typeReg(),
+                 s1 = src.payloadReg(), d1 = dest.payloadReg();
+
+        // Either one or both of the source registers could be the same as a
+        // destination register.
+        if (s1 == d0) {
+            if (s0 == d1) {
+                // If both are, this is just a swap of two registers.
+                ScratchRegisterScope scratch(asMasm());
+                MOZ_ASSERT(d1 != scratch);
+                MOZ_ASSERT(d0 != scratch);
+                ma_mov(d1, scratch);
+                ma_mov(d0, d1);
+                ma_mov(scratch, d0);
+                return;
+            }
+            // If only one is, copy that source first.
+            mozilla::Swap(s0, s1);
+            mozilla::Swap(d0, d1);
+        }
+
+        if (s0 != d0)
+            ma_mov(s0, d0);
+        if (s1 != d1)
+            ma_mov(s1, d1);
+    }
+
+    void storeValue(ValueOperand val, const Address& dst);
+    void storeValue(ValueOperand val, const BaseIndex& dest);
+    void storeValue(JSValueType type, Register reg, BaseIndex dest) {
+        ScratchRegisterScope scratch(asMasm());
+        SecondScratchRegisterScope scratch2(asMasm());
+
+        int32_t payloadoffset = dest.offset + NUNBOX32_PAYLOAD_OFFSET;
+        int32_t typeoffset = dest.offset + NUNBOX32_TYPE_OFFSET;
+
+        ma_alu(dest.base, lsl(dest.index, dest.scale), scratch, OpAdd);
+
+        // Store the payload.
+        if (payloadoffset < 4096 && payloadoffset > -4096)
+            ma_str(reg, DTRAddr(scratch, DtrOffImm(payloadoffset)));
+        else
+            ma_str(reg, Address(scratch, payloadoffset), scratch2);
+
+        // Store the type.
+        if (typeoffset < 4096 && typeoffset > -4096) {
+            // Encodable as DTRAddr, so only two instructions needed.
+            ma_mov(ImmTag(JSVAL_TYPE_TO_TAG(type)), scratch2);
+            ma_str(scratch2, DTRAddr(scratch, DtrOffImm(typeoffset)));
+        } else {
+            // Since there are only two scratch registers, the offset must be
+            // applied early using a third instruction to be safe.
+            ma_add(Imm32(typeoffset), scratch, scratch2);
+            ma_mov(ImmTag(JSVAL_TYPE_TO_TAG(type)), scratch2);
+            ma_str(scratch2, DTRAddr(scratch, DtrOffImm(0)));
+        }
+    }
+    void storeValue(JSValueType type, Register reg, Address dest) {
+        ScratchRegisterScope scratch(asMasm());
+        SecondScratchRegisterScope scratch2(asMasm());
+
+        ma_str(reg, dest, scratch2);
+        ma_mov(ImmTag(JSVAL_TYPE_TO_TAG(type)), scratch);
+        ma_str(scratch, Address(dest.base, dest.offset + NUNBOX32_TYPE_OFFSET), scratch2);
+    }
+    void storeValue(const Value& val, const Address& dest) {
+        ScratchRegisterScope scratch(asMasm());
+        SecondScratchRegisterScope scratch2(asMasm());
+
+        ma_mov(Imm32(val.toNunboxTag()), scratch);
+        ma_str(scratch, ToType(dest), scratch2);
+        if (val.isMarkable())
+            ma_mov(ImmGCPtr(val.toMarkablePointer()), scratch);
+        else
+            ma_mov(Imm32(val.toNunboxPayload()), scratch);
+        ma_str(scratch, ToPayload(dest), scratch2);
+    }
+    void storeValue(const Value& val, BaseIndex dest) {
+        ScratchRegisterScope scratch(asMasm());
+        SecondScratchRegisterScope scratch2(asMasm());
+
+        int32_t typeoffset = dest.offset + NUNBOX32_TYPE_OFFSET;
+        int32_t payloadoffset = dest.offset + NUNBOX32_PAYLOAD_OFFSET;
+
+        ma_alu(dest.base, lsl(dest.index, dest.scale), scratch, OpAdd);
+
+        // Store the type.
+        if (typeoffset < 4096 && typeoffset > -4096) {
+            ma_mov(Imm32(val.toNunboxTag()), scratch2);
+            ma_str(scratch2, DTRAddr(scratch, DtrOffImm(typeoffset)));
+        } else {
+            ma_add(Imm32(typeoffset), scratch, scratch2);
+            ma_mov(Imm32(val.toNunboxTag()), scratch2);
+            ma_str(scratch2, DTRAddr(scratch, DtrOffImm(0)));
+            // Restore scratch for the payload store.
+            ma_alu(dest.base, lsl(dest.index, dest.scale), scratch, OpAdd);
+        }
+
+        // Store the payload, marking if necessary.
+        if (payloadoffset < 4096 && payloadoffset > -4096) {
+            if (val.isMarkable())
+                ma_mov(ImmGCPtr(val.toMarkablePointer()), scratch2);
+            else
+                ma_mov(Imm32(val.toNunboxPayload()), scratch2);
+            ma_str(scratch2, DTRAddr(scratch, DtrOffImm(payloadoffset)));
+        } else {
+            ma_add(Imm32(payloadoffset), scratch, scratch2);
+            if (val.isMarkable())
+                ma_mov(ImmGCPtr(val.toMarkablePointer()), scratch2);
+            else
+                ma_mov(Imm32(val.toNunboxPayload()), scratch2);
+            ma_str(scratch2, DTRAddr(scratch, DtrOffImm(0)));
+        }
+    }
+    void storeValue(const Address& src, const Address& dest, Register temp) {
+        load32(ToType(src), temp);
+        store32(temp, ToType(dest));
+
+        load32(ToPayload(src), temp);
+        store32(temp, ToPayload(dest));
+    }
+
+    void loadValue(Address src, ValueOperand val);
+    void loadValue(Operand dest, ValueOperand val) {
+        loadValue(dest.toAddress(), val);
+    }
+    void loadValue(const BaseIndex& addr, ValueOperand val);
+    void tagValue(JSValueType type, Register payload, ValueOperand dest);
+
+    void pushValue(ValueOperand val);
+    void popValue(ValueOperand val);
+    void pushValue(const Value& val) {
+        push(Imm32(val.toNunboxTag()));
+        if (val.isMarkable())
+            push(ImmGCPtr(val.toMarkablePointer()));
+        else
+            push(Imm32(val.toNunboxPayload()));
+    }
+    void pushValue(JSValueType type, Register reg) {
+        push(ImmTag(JSVAL_TYPE_TO_TAG(type)));
+        ma_push(reg);
+    }
+    void pushValue(const Address& addr);
+
+    void storePayload(const Value& val, const Address& dest);
+    void storePayload(Register src, const Address& dest);
+    void storePayload(const Value& val, const BaseIndex& dest);
+    void storePayload(Register src, const BaseIndex& dest);
+    void storeTypeTag(ImmTag tag, const Address& dest);
+    void storeTypeTag(ImmTag tag, const BaseIndex& dest);
+
+    void handleFailureWithHandlerTail(void* handler);
+
+    /////////////////////////////////////////////////////////////////
+    // Common interface.
+    /////////////////////////////////////////////////////////////////
+  public:
+    void not32(Register reg);
+
+    void move32(Imm32 imm, Register dest);
+    void move32(Register src, Register dest);
+
+    void movePtr(Register src, Register dest);
+    void movePtr(ImmWord imm, Register dest);
+    void movePtr(ImmPtr imm, Register dest);
+    void movePtr(wasm::SymbolicAddress imm, Register dest);
+    void movePtr(ImmGCPtr imm, Register dest);
+
+    void load8SignExtend(const Address& address, Register dest);
+    void load8SignExtend(const BaseIndex& src, Register dest);
+
+    void load8ZeroExtend(const Address& address, Register dest);
+    void load8ZeroExtend(const BaseIndex& src, Register dest);
+
+    void load16SignExtend(const Address& address, Register dest);
+    void load16SignExtend(const BaseIndex& src, Register dest);
+
+    void load16ZeroExtend(const Address& address, Register dest);
+    void load16ZeroExtend(const BaseIndex& src, Register dest);
+
+    void load32(const Address& address, Register dest);
+    void load32(const BaseIndex& address, Register dest);
+    void load32(AbsoluteAddress address, Register dest);
+    void load64(const Address& address, Register64 dest) {
+        load32(Address(address.base, address.offset + INT64LOW_OFFSET), dest.low);
+        int32_t highOffset = (address.offset < 0) ? -int32_t(INT64HIGH_OFFSET) : INT64HIGH_OFFSET;
+        load32(Address(address.base, address.offset + highOffset), dest.high);
+    }
+
+    void loadPtr(const Address& address, Register dest);
+    void loadPtr(const BaseIndex& src, Register dest);
+    void loadPtr(AbsoluteAddress address, Register dest);
+    void loadPtr(wasm::SymbolicAddress address, Register dest);
+
+    void loadPrivate(const Address& address, Register dest);
+
+    void loadInt32x1(const Address& addr, FloatRegister dest) { MOZ_CRASH("NYI"); }
+    void loadInt32x1(const BaseIndex& addr, FloatRegister dest) { MOZ_CRASH("NYI"); }
+    void loadInt32x2(const Address& addr, FloatRegister dest) { MOZ_CRASH("NYI"); }
+    void loadInt32x2(const BaseIndex& addr, FloatRegister dest) { MOZ_CRASH("NYI"); }
+    void loadInt32x3(const Address& src, FloatRegister dest) { MOZ_CRASH("NYI"); }
+    void loadInt32x3(const BaseIndex& src, FloatRegister dest) { MOZ_CRASH("NYI"); }
+    void storeInt32x1(FloatRegister src, const Address& dest) { MOZ_CRASH("NYI"); }
+    void storeInt32x1(FloatRegister src, const BaseIndex& dest) { MOZ_CRASH("NYI"); }
+    void storeInt32x2(FloatRegister src, const Address& dest) { MOZ_CRASH("NYI"); }
+    void storeInt32x2(FloatRegister src, const BaseIndex& dest) { MOZ_CRASH("NYI"); }
+    void storeInt32x3(FloatRegister src, const Address& dest) { MOZ_CRASH("NYI"); }
+    void storeInt32x3(FloatRegister src, const BaseIndex& dest) { MOZ_CRASH("NYI"); }
+    void loadAlignedSimd128Int(const Address& addr, FloatRegister dest) { MOZ_CRASH("NYI"); }
+    void storeAlignedSimd128Int(FloatRegister src, Address addr) { MOZ_CRASH("NYI"); }
+    void loadUnalignedSimd128Int(const Address& addr, FloatRegister dest) { MOZ_CRASH("NYI"); }
+    void loadUnalignedSimd128Int(const BaseIndex& addr, FloatRegister dest) { MOZ_CRASH("NYI"); }
+    void storeUnalignedSimd128Int(FloatRegister src, Address addr) { MOZ_CRASH("NYI"); }
+    void storeUnalignedSimd128Int(FloatRegister src, BaseIndex addr) { MOZ_CRASH("NYI"); }
+
+    void loadFloat32x3(const Address& src, FloatRegister dest) { MOZ_CRASH("NYI"); }
+    void loadFloat32x3(const BaseIndex& src, FloatRegister dest) { MOZ_CRASH("NYI"); }
+    void loadAlignedSimd128Float(const Address& addr, FloatRegister dest) { MOZ_CRASH("NYI"); }
+    void storeAlignedSimd128Float(FloatRegister src, Address addr) { MOZ_CRASH("NYI"); }
+    void loadUnalignedSimd128Float(const Address& addr, FloatRegister dest) { MOZ_CRASH("NYI"); }
+    void loadUnalignedSimd128Float(const BaseIndex& addr, FloatRegister dest) { MOZ_CRASH("NYI"); }
+    void storeUnalignedSimd128Float(FloatRegister src, Address addr) { MOZ_CRASH("NYI"); }
+    void storeUnalignedSimd128Float(FloatRegister src, BaseIndex addr) { MOZ_CRASH("NYI"); }
+
+    void loadDouble(const Address& addr, FloatRegister dest);
+    void loadDouble(const BaseIndex& src, FloatRegister dest);
+
+    // Load a float value into a register, then expand it to a double.
+    void loadFloatAsDouble(const Address& addr, FloatRegister dest);
+    void loadFloatAsDouble(const BaseIndex& src, FloatRegister dest);
+
+    void loadFloat32(const Address& addr, FloatRegister dest);
+    void loadFloat32(const BaseIndex& src, FloatRegister dest);
+
+    void store8(Register src, const Address& address);
+    void store8(Imm32 imm, const Address& address);
+    void store8(Register src, const BaseIndex& address);
+    void store8(Imm32 imm, const BaseIndex& address);
+
+    void store16(Register src, const Address& address);
+    void store16(Imm32 imm, const Address& address);
+    void store16(Register src, const BaseIndex& address);
+    void store16(Imm32 imm, const BaseIndex& address);
+
+    void store32(Register src, AbsoluteAddress address);
+    void store32(Register src, const Address& address);
+    void store32(Register src, const BaseIndex& address);
+    void store32(Imm32 src, const Address& address);
+    void store32(Imm32 src, const BaseIndex& address);
+
+    void store64(Register64 src, Address address) {
+        store32(src.low, Address(address.base, address.offset + INT64LOW_OFFSET));
+        store32(src.high, Address(address.base, address.offset + INT64HIGH_OFFSET));
+    }
+
+    void store64(Imm64 imm, Address address) {
+        store32(imm.low(), Address(address.base, address.offset + INT64LOW_OFFSET));
+        store32(imm.hi(), Address(address.base, address.offset + INT64HIGH_OFFSET));
+    }
+
+    void storePtr(ImmWord imm, const Address& address);
+    void storePtr(ImmWord imm, const BaseIndex& address);
+    void storePtr(ImmPtr imm, const Address& address);
+    void storePtr(ImmPtr imm, const BaseIndex& address);
+    void storePtr(ImmGCPtr imm, const Address& address);
+    void storePtr(ImmGCPtr imm, const BaseIndex& address);
+    void storePtr(Register src, const Address& address);
+    void storePtr(Register src, const BaseIndex& address);
+    void storePtr(Register src, AbsoluteAddress dest);
+
+    void moveDouble(FloatRegister src, FloatRegister dest, Condition cc = Always) {
+        ma_vmov(src, dest, cc);
+    }
+
+  private:
+    template<typename T>
+    Register computePointer(const T& src, Register r);
+
+    template<typename T>
+    void compareExchangeARMv6(int nbytes, bool signExtend, const T& mem, Register oldval,
+                              Register newval, Register output);
+
+    template<typename T>
+    void compareExchangeARMv7(int nbytes, bool signExtend, const T& mem, Register oldval,
+                              Register newval, Register output);
+
+    template<typename T>
+    void compareExchange(int nbytes, bool signExtend, const T& address, Register oldval,
+                         Register newval, Register output);
+
+    template<typename T>
+    void atomicExchangeARMv6(int nbytes, bool signExtend, const T& mem, Register value,
+                             Register output);
+
+    template<typename T>
+    void atomicExchangeARMv7(int nbytes, bool signExtend, const T& mem, Register value,
+                             Register output);
+
+    template<typename T>
+    void atomicExchange(int nbytes, bool signExtend, const T& address, Register value,
+                        Register output);
+
+    template<typename T>
+    void atomicFetchOpARMv6(int nbytes, bool signExtend, AtomicOp op, const Register& value,
+                            const T& mem, Register flagTemp, Register output);
+
+    template<typename T>
+    void atomicFetchOpARMv7(int nbytes, bool signExtend, AtomicOp op, const Register& value,
+                            const T& mem, Register flagTemp, Register output);
+
+    template<typename T>
+    void atomicFetchOp(int nbytes, bool signExtend, AtomicOp op, const Imm32& value,
+                       const T& address, Register flagTemp, Register output);
+
+    template<typename T>
+    void atomicFetchOp(int nbytes, bool signExtend, AtomicOp op, const Register& value,
+                       const T& address, Register flagTemp, Register output);
+
+    template<typename T>
+    void atomicEffectOpARMv6(int nbytes, AtomicOp op, const Register& value, const T& address,
+                             Register flagTemp);
+
+    template<typename T>
+    void atomicEffectOpARMv7(int nbytes, AtomicOp op, const Register& value, const T& address,
+                             Register flagTemp);
+
+    template<typename T>
+    void atomicEffectOp(int nbytes, AtomicOp op, const Imm32& value, const T& address,
+                             Register flagTemp);
+
+    template<typename T>
+    void atomicEffectOp(int nbytes, AtomicOp op, const Register& value, const T& address,
+                             Register flagTemp);
+
+  public:
+    // T in {Address,BaseIndex}
+    // S in {Imm32,Register}
+
+    template<typename T>
+    void compareExchange8SignExtend(const T& mem, Register oldval, Register newval, Register output)
+    {
+        compareExchange(1, true, mem, oldval, newval, output);
+    }
+    template<typename T>
+    void compareExchange8ZeroExtend(const T& mem, Register oldval, Register newval, Register output)
+    {
+        compareExchange(1, false, mem, oldval, newval, output);
+    }
+    template<typename T>
+    void compareExchange16SignExtend(const T& mem, Register oldval, Register newval, Register output)
+    {
+        compareExchange(2, true, mem, oldval, newval, output);
+    }
+    template<typename T>
+    void compareExchange16ZeroExtend(const T& mem, Register oldval, Register newval, Register output)
+    {
+        compareExchange(2, false, mem, oldval, newval, output);
+    }
+    template<typename T>
+    void compareExchange32(const T& mem, Register oldval, Register newval, Register output)  {
+        compareExchange(4, false, mem, oldval, newval, output);
+    }
+
+    template<typename T>
+    void atomicExchange8SignExtend(const T& mem, Register value, Register output)
+    {
+        atomicExchange(1, true, mem, value, output);
+    }
+    template<typename T>
+    void atomicExchange8ZeroExtend(const T& mem, Register value, Register output)
+    {
+        atomicExchange(1, false, mem, value, output);
+    }
+    template<typename T>
+    void atomicExchange16SignExtend(const T& mem, Register value, Register output)
+    {
+        atomicExchange(2, true, mem, value, output);
+    }
+    template<typename T>
+    void atomicExchange16ZeroExtend(const T& mem, Register value, Register output)
+    {
+        atomicExchange(2, false, mem, value, output);
+    }
+    template<typename T>
+    void atomicExchange32(const T& mem, Register value, Register output) {
+        atomicExchange(4, false, mem, value, output);
+    }
+
+    template<typename T, typename S>
+    void atomicFetchAdd8SignExtend(const S& value, const T& mem, Register temp, Register output) {
+        atomicFetchOp(1, true, AtomicFetchAddOp, value, mem, temp, output);
+    }
+    template<typename T, typename S>
+    void atomicFetchAdd8ZeroExtend(const S& value, const T& mem, Register temp, Register output) {
+        atomicFetchOp(1, false, AtomicFetchAddOp, value, mem, temp, output);
+    }
+    template<typename T, typename S>
+    void atomicFetchAdd16SignExtend(const S& value, const T& mem, Register temp, Register output) {
+        atomicFetchOp(2, true, AtomicFetchAddOp, value, mem, temp, output);
+    }
+    template<typename T, typename S>
+    void atomicFetchAdd16ZeroExtend(const S& value, const T& mem, Register temp, Register output) {
+        atomicFetchOp(2, false, AtomicFetchAddOp, value, mem, temp, output);
+    }
+    template<typename T, typename S>
+    void atomicFetchAdd32(const S& value, const T& mem, Register temp, Register output) {
+        atomicFetchOp(4, false, AtomicFetchAddOp, value, mem, temp, output);
+    }
+    template <typename T, typename S>
+    void atomicAdd8(const S& value, const T& mem, Register flagTemp) {
+        atomicEffectOp(1, AtomicFetchAddOp, value, mem, flagTemp);
+    }
+    template <typename T, typename S>
+    void atomicAdd16(const S& value, const T& mem, Register flagTemp) {
+        atomicEffectOp(2, AtomicFetchAddOp, value, mem, flagTemp);
+    }
+    template <typename T, typename S>
+    void atomicAdd32(const S& value, const T& mem, Register flagTemp) {
+        atomicEffectOp(4, AtomicFetchAddOp, value, mem, flagTemp);
+    }
+
+    template<typename T, typename S>
+    void atomicFetchSub8SignExtend(const S& value, const T& mem, Register temp, Register output) {
+        atomicFetchOp(1, true, AtomicFetchSubOp, value, mem, temp, output);
+    }
+    template<typename T, typename S>
+    void atomicFetchSub8ZeroExtend(const S& value, const T& mem, Register temp, Register output) {
+        atomicFetchOp(1, false, AtomicFetchSubOp, value, mem, temp, output);
+    }
+    template<typename T, typename S>
+    void atomicFetchSub16SignExtend(const S& value, const T& mem, Register temp, Register output) {
+        atomicFetchOp(2, true, AtomicFetchSubOp, value, mem, temp, output);
+    }
+    template<typename T, typename S>
+    void atomicFetchSub16ZeroExtend(const S& value, const T& mem, Register temp, Register output) {
+        atomicFetchOp(2, false, AtomicFetchSubOp, value, mem, temp, output);
+    }
+    template<typename T, typename S>
+    void atomicFetchSub32(const S& value, const T& mem, Register temp, Register output) {
+        atomicFetchOp(4, false, AtomicFetchSubOp, value, mem, temp, output);
+    }
+    template <typename T, typename S>
+    void atomicSub8(const S& value, const T& mem, Register flagTemp) {
+        atomicEffectOp(1, AtomicFetchSubOp, value, mem, flagTemp);
+    }
+    template <typename T, typename S>
+    void atomicSub16(const S& value, const T& mem, Register flagTemp) {
+        atomicEffectOp(2, AtomicFetchSubOp, value, mem, flagTemp);
+    }
+    template <typename T, typename S>
+    void atomicSub32(const S& value, const T& mem, Register flagTemp) {
+        atomicEffectOp(4, AtomicFetchSubOp, value, mem, flagTemp);
+    }
+
+    template<typename T, typename S>
+    void atomicFetchAnd8SignExtend(const S& value, const T& mem, Register temp, Register output) {
+        atomicFetchOp(1, true, AtomicFetchAndOp, value, mem, temp, output);
+    }
+    template<typename T, typename S>
+    void atomicFetchAnd8ZeroExtend(const S& value, const T& mem, Register temp, Register output) {
+        atomicFetchOp(1, false, AtomicFetchAndOp, value, mem, temp, output);
+    }
+    template<typename T, typename S>
+    void atomicFetchAnd16SignExtend(const S& value, const T& mem, Register temp, Register output) {
+        atomicFetchOp(2, true, AtomicFetchAndOp, value, mem, temp, output);
+    }
+    template<typename T, typename S>
+    void atomicFetchAnd16ZeroExtend(const S& value, const T& mem, Register temp, Register output) {
+        atomicFetchOp(2, false, AtomicFetchAndOp, value, mem, temp, output);
+    }
+    template<typename T, typename S>
+    void atomicFetchAnd32(const S& value, const T& mem, Register temp, Register output) {
+        atomicFetchOp(4, false, AtomicFetchAndOp, value, mem, temp, output);
+    }
+    template <typename T, typename S>
+    void atomicAnd8(const S& value, const T& mem, Register flagTemp) {
+        atomicEffectOp(1, AtomicFetchAndOp, value, mem, flagTemp);
+    }
+    template <typename T, typename S>
+    void atomicAnd16(const S& value, const T& mem, Register flagTemp) {
+        atomicEffectOp(2, AtomicFetchAndOp, value, mem, flagTemp);
+    }
+    template <typename T, typename S>
+    void atomicAnd32(const S& value, const T& mem, Register flagTemp) {
+        atomicEffectOp(4, AtomicFetchAndOp, value, mem, flagTemp);
+    }
+
+    template<typename T, typename S>
+    void atomicFetchOr8SignExtend(const S& value, const T& mem, Register temp, Register output) {
+        atomicFetchOp(1, true, AtomicFetchOrOp, value, mem, temp, output);
+    }
+    template<typename T, typename S>
+    void atomicFetchOr8ZeroExtend(const S& value, const T& mem, Register temp, Register output) {
+        atomicFetchOp(1, false, AtomicFetchOrOp, value, mem, temp, output);
+    }
+    template<typename T, typename S>
+    void atomicFetchOr16SignExtend(const S& value, const T& mem, Register temp, Register output) {
+        atomicFetchOp(2, true, AtomicFetchOrOp, value, mem, temp, output);
+    }
+    template<typename T, typename S>
+    void atomicFetchOr16ZeroExtend(const S& value, const T& mem, Register temp, Register output) {
+        atomicFetchOp(2, false, AtomicFetchOrOp, value, mem, temp, output);
+    }
+    template<typename T, typename S>
+    void atomicFetchOr32(const S& value, const T& mem, Register temp, Register output) {
+        atomicFetchOp(4, false, AtomicFetchOrOp, value, mem, temp, output);
+    }
+    template <typename T, typename S>
+    void atomicOr8(const S& value, const T& mem, Register flagTemp) {
+        atomicEffectOp(1, AtomicFetchOrOp, value, mem, flagTemp);
+    }
+    template <typename T, typename S>
+    void atomicOr16(const S& value, const T& mem, Register flagTemp) {
+        atomicEffectOp(2, AtomicFetchOrOp, value, mem, flagTemp);
+    }
+    template <typename T, typename S>
+    void atomicOr32(const S& value, const T& mem, Register flagTemp) {
+        atomicEffectOp(4, AtomicFetchOrOp, value, mem, flagTemp);
+    }
+
+    template<typename T, typename S>
+    void atomicFetchXor8SignExtend(const S& value, const T& mem, Register temp, Register output) {
+        atomicFetchOp(1, true, AtomicFetchXorOp, value, mem, temp, output);
+    }
+    template<typename T, typename S>
+    void atomicFetchXor8ZeroExtend(const S& value, const T& mem, Register temp, Register output) {
+        atomicFetchOp(1, false, AtomicFetchXorOp, value, mem, temp, output);
+    }
+    template<typename T, typename S>
+    void atomicFetchXor16SignExtend(const S& value, const T& mem, Register temp, Register output) {
+        atomicFetchOp(2, true, AtomicFetchXorOp, value, mem, temp, output);
+    }
+    template<typename T, typename S>
+    void atomicFetchXor16ZeroExtend(const S& value, const T& mem, Register temp, Register output) {
+        atomicFetchOp(2, false, AtomicFetchXorOp, value, mem, temp, output);
+    }
+    template<typename T, typename S>
+    void atomicFetchXor32(const S& value, const T& mem, Register temp, Register output) {
+        atomicFetchOp(4, false, AtomicFetchXorOp, value, mem, temp, output);
+    }
+    template <typename T, typename S>
+    void atomicXor8(const S& value, const T& mem, Register flagTemp) {
+        atomicEffectOp(1, AtomicFetchXorOp, value, mem, flagTemp);
+    }
+    template <typename T, typename S>
+    void atomicXor16(const S& value, const T& mem, Register flagTemp) {
+        atomicEffectOp(2, AtomicFetchXorOp, value, mem, flagTemp);
+    }
+    template <typename T, typename S>
+    void atomicXor32(const S& value, const T& mem, Register flagTemp) {
+        atomicEffectOp(4, AtomicFetchXorOp, value, mem, flagTemp);
+    }
+
+    template<typename T>
+    void compareExchangeToTypedIntArray(Scalar::Type arrayType, const T& mem, Register oldval, Register newval,
+                                        Register temp, AnyRegister output);
+
+    template<typename T>
+    void atomicExchangeToTypedIntArray(Scalar::Type arrayType, const T& mem, Register value,
+                                       Register temp, AnyRegister output);
+
+    inline void incrementInt32Value(const Address& addr);
+
+    void cmp32(Register lhs, Imm32 rhs);
+    void cmp32(Register lhs, Register rhs);
+    void cmp32(const Address& lhs, Imm32 rhs) {
+        MOZ_CRASH("NYI");
+    }
+    void cmp32(const Address& lhs, Register rhs) {
+        MOZ_CRASH("NYI");
+    }
+
+    void cmpPtr(Register lhs, Register rhs);
+    void cmpPtr(Register lhs, ImmWord rhs);
+    void cmpPtr(Register lhs, ImmPtr rhs);
+    void cmpPtr(Register lhs, ImmGCPtr rhs);
+    void cmpPtr(Register lhs, Imm32 rhs);
+    void cmpPtr(const Address& lhs, Register rhs);
+    void cmpPtr(const Address& lhs, ImmWord rhs);
+    void cmpPtr(const Address& lhs, ImmPtr rhs);
+    void cmpPtr(const Address& lhs, ImmGCPtr rhs);
+    void cmpPtr(const Address& lhs, Imm32 rhs);
+
+    static bool convertUInt64ToDoubleNeedsTemp();
+    void convertUInt64ToDouble(Register64 src, FloatRegister dest, Register temp);
+
+    void setStackArg(Register reg, uint32_t arg);
+
+    void breakpoint();
+    // Conditional breakpoint.
+    void breakpoint(Condition cc);
+
+    // Trigger the simulator's interactive read-eval-print loop.
+    // The message will be printed at the stopping point.
+    // (On non-simulator builds, does nothing.)
+    void simulatorStop(const char* msg);
+
+    // Evaluate srcDest = minmax<isMax>{Float32,Double}(srcDest, other).
+    // Checks for NaN if canBeNaN is true.
+    void minMaxDouble(FloatRegister srcDest, FloatRegister other, bool canBeNaN, bool isMax);
+    void minMaxFloat32(FloatRegister srcDest, FloatRegister other, bool canBeNaN, bool isMax);
+
+    void compareDouble(FloatRegister lhs, FloatRegister rhs);
+
+    void compareFloat(FloatRegister lhs, FloatRegister rhs);
+
+    void checkStackAlignment();
+
+    // If source is a double, load it into dest. If source is int32, convert it
+    // to double. Else, branch to failure.
+    void ensureDouble(const ValueOperand& source, FloatRegister dest, Label* failure);
+
+    void
+    emitSet(Assembler::Condition cond, Register dest)
+    {
+        ma_mov(Imm32(0), dest);
+        ma_mov(Imm32(1), dest, cond);
+    }
+
+    void testNullSet(Condition cond, const ValueOperand& value, Register dest) {
+        cond = testNull(cond, value);
+        emitSet(cond, dest);
+    }
+
+    void testObjectSet(Condition cond, const ValueOperand& value, Register dest) {
+        cond = testObject(cond, value);
+        emitSet(cond, dest);
+    }
+
+    void testUndefinedSet(Condition cond, const ValueOperand& value, Register dest) {
+        cond = testUndefined(cond, value);
+        emitSet(cond, dest);
+    }
+
+  protected:
+    bool buildOOLFakeExitFrame(void* fakeReturnAddr);
+
+  public:
+    CodeOffset labelForPatch() {
+        return CodeOffset(nextOffset().getOffset());
+    }
+
+    void computeEffectiveAddress(const Address& address, Register dest) {
+        ScratchRegisterScope scratch(asMasm());
+        ma_add(address.base, Imm32(address.offset), dest, scratch, LeaveCC);
+    }
+    void computeEffectiveAddress(const BaseIndex& address, Register dest) {
+        ScratchRegisterScope scratch(asMasm());
+        ma_alu(address.base, lsl(address.index, address.scale), dest, OpAdd, LeaveCC);
+        if (address.offset)
+            ma_add(dest, Imm32(address.offset), dest, scratch, LeaveCC);
+    }
+    void floor(FloatRegister input, Register output, Label* handleNotAnInt);
+    void floorf(FloatRegister input, Register output, Label* handleNotAnInt);
+    void ceil(FloatRegister input, Register output, Label* handleNotAnInt);
+    void ceilf(FloatRegister input, Register output, Label* handleNotAnInt);
+    void round(FloatRegister input, Register output, Label* handleNotAnInt, FloatRegister tmp);
+    void roundf(FloatRegister input, Register output, Label* handleNotAnInt, FloatRegister tmp);
+
+    void clampCheck(Register r, Label* handleNotAnInt) {
+        // Check explicitly for r == INT_MIN || r == INT_MAX
+        // This is the instruction sequence that gcc generated for this
+        // operation.
+        ScratchRegisterScope scratch(asMasm());
+        SecondScratchRegisterScope scratch2(asMasm());
+        ma_sub(r, Imm32(0x80000001), scratch, scratch2);
+        as_cmn(scratch, Imm8(3));
+        ma_b(handleNotAnInt, Above);
+    }
+
+    void lea(Operand addr, Register dest) {
+        ScratchRegisterScope scratch(asMasm());
+        ma_add(addr.baseReg(), Imm32(addr.disp()), dest, scratch);
+    }
+
+    void abiret() {
+        as_bx(lr);
+    }
+
+    void moveFloat32(FloatRegister src, FloatRegister dest, Condition cc = Always) {
+        as_vmov(VFPRegister(dest).singleOverlay(), VFPRegister(src).singleOverlay(), cc);
+    }
+
+    void loadWasmGlobalPtr(uint32_t globalDataOffset, Register dest) {
+        loadPtr(Address(GlobalReg, globalDataOffset - WasmGlobalRegBias), dest);
+    }
+    void loadWasmPinnedRegsFromTls() {
+        ScratchRegisterScope scratch(asMasm());
+        ma_ldr(Address(WasmTlsReg, offsetof(wasm::TlsData, memoryBase)), HeapReg, scratch);
+        ma_ldr(Address(WasmTlsReg, offsetof(wasm::TlsData, globalData)), GlobalReg, scratch);
+        ma_add(Imm32(WasmGlobalRegBias), GlobalReg, scratch);
+    }
+
+    // Instrumentation for entering and leaving the profiler.
+    void profilerEnterFrame(Register framePtr, Register scratch);
+    void profilerExitFrame();
+
+    struct AutoPrepareForPatching {
+        explicit AutoPrepareForPatching(MacroAssemblerARMCompat&) {}
+    };
+};
+
+typedef MacroAssemblerARMCompat MacroAssemblerSpecific;
+
+} // namespace jit
+} // namespace js
+
+#endif /* jit_arm_MacroAssembler_arm_h */
diff --git a/js/src/jit/arm/MoveEmitter-arm.cpp b/js/src/jit/arm/MoveEmitter-arm.cpp
new file mode 100644
index 0000000000..edacd6913f
--- /dev/null
+++ b/js/src/jit/arm/MoveEmitter-arm.cpp
@@ -0,0 +1,427 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "jit/arm/MoveEmitter-arm.h"
+
+#include "jit/MacroAssembler-inl.h"
+
+using namespace js;
+using namespace js::jit;
+
+MoveEmitterARM::MoveEmitterARM(MacroAssembler& masm)
+  : inCycle_(0),
+    masm(masm),
+    pushedAtCycle_(-1),
+    pushedAtSpill_(-1),
+    spilledReg_(InvalidReg),
+    spilledFloatReg_(InvalidFloatReg)
+{
+    pushedAtStart_ = masm.framePushed();
+}
+
+void
+MoveEmitterARM::emit(const MoveResolver& moves)
+{
+    if (moves.numCycles()) {
+        // Reserve stack for cycle resolution
+        masm.reserveStack(moves.numCycles() * sizeof(double));
+        pushedAtCycle_ = masm.framePushed();
+    }
+
+    for (size_t i = 0; i < moves.numMoves(); i++)
+        emit(moves.getMove(i));
+}
+
+MoveEmitterARM::~MoveEmitterARM()
+{
+    assertDone();
+}
+
+Address
+MoveEmitterARM::cycleSlot(uint32_t slot, uint32_t subslot) const
+{
+    int32_t offset =  masm.framePushed() - pushedAtCycle_;
+    MOZ_ASSERT(offset < 4096 && offset > -4096);
+    return Address(StackPointer, offset + slot * sizeof(double) + subslot);
+}
+
+Address
+MoveEmitterARM::spillSlot() const
+{
+    int32_t offset =  masm.framePushed() - pushedAtSpill_;
+    MOZ_ASSERT(offset < 4096 && offset > -4096);
+    return Address(StackPointer, offset);
+}
+
+Address
+MoveEmitterARM::toAddress(const MoveOperand& operand) const
+{
+    MOZ_ASSERT(operand.isMemoryOrEffectiveAddress());
+
+    if (operand.base() != StackPointer) {
+        MOZ_ASSERT(operand.disp() < 1024 && operand.disp() > -1024);
+        return Operand(operand.base(), operand.disp()).toAddress();
+    }
+
+    MOZ_ASSERT(operand.disp() >= 0);
+
+    // Otherwise, the stack offset may need to be adjusted.
+    return Address(StackPointer, operand.disp() + (masm.framePushed() - pushedAtStart_));
+}
+
+Register
+MoveEmitterARM::tempReg()
+{
+    if (spilledReg_ != InvalidReg)
+        return spilledReg_;
+
+    // For now, just pick r12/ip as the eviction point. This is totally random,
+    // and if it ends up being bad, we can use actual heuristics later. r12 is
+    // actually a bad choice. It is the scratch register, which is frequently
+    // used for address computations, such as those found when we attempt to
+    // access values more than 4096 off of the stack pointer. Instead, use lr,
+    // the LinkRegister.
+    spilledReg_ = r14;
+    if (pushedAtSpill_ == -1) {
+        masm.Push(spilledReg_);
+        pushedAtSpill_ = masm.framePushed();
+    } else {
+        ScratchRegisterScope scratch(masm);
+        masm.ma_str(spilledReg_, spillSlot(), scratch);
+    }
+    return spilledReg_;
+}
+
+void
+MoveEmitterARM::breakCycle(const MoveOperand& from, const MoveOperand& to,
+                           MoveOp::Type type, uint32_t slotId)
+{
+    // There is some pattern:
+    //   (A -> B)
+    //   (B -> A)
+    //
+    // This case handles (A -> B), which we reach first. We save B, then allow
+    // the original move to continue.
+
+    ScratchRegisterScope scratch(masm);
+
+    switch (type) {
+      case MoveOp::FLOAT32:
+        if (to.isMemory()) {
+            ScratchFloat32Scope scratchFloat32(masm);
+            masm.ma_vldr(toAddress(to), scratchFloat32, scratch);
+            // Since it is uncertain if the load will be aligned or not
+            // just fill both of them with the same value.
+            masm.ma_vstr(scratchFloat32, cycleSlot(slotId, 0), scratch);
+            masm.ma_vstr(scratchFloat32, cycleSlot(slotId, 4), scratch);
+        } else if (to.isGeneralReg()) {
+            // Since it is uncertain if the load will be aligned or not
+            // just fill both of them with the same value.
+            masm.ma_str(to.reg(), cycleSlot(slotId, 0), scratch);
+            masm.ma_str(to.reg(), cycleSlot(slotId, 4), scratch);
+        } else {
+            FloatRegister src = to.floatReg();
+            // Just always store the largest possible size. Currently, this is
+            // a double. When SIMD is added, two doubles will need to be stored.
+            masm.ma_vstr(src.doubleOverlay(), cycleSlot(slotId, 0), scratch);
+        }
+        break;
+      case MoveOp::DOUBLE:
+        if (to.isMemory()) {
+            ScratchDoubleScope scratchDouble(masm);
+            masm.ma_vldr(toAddress(to), scratchDouble, scratch);
+            masm.ma_vstr(scratchDouble, cycleSlot(slotId, 0), scratch);
+        } else if (to.isGeneralRegPair()) {
+            ScratchDoubleScope scratchDouble(masm);
+            masm.ma_vxfer(to.evenReg(), to.oddReg(), scratchDouble);
+            masm.ma_vstr(scratchDouble, cycleSlot(slotId, 0), scratch);
+        } else {
+            masm.ma_vstr(to.floatReg().doubleOverlay(), cycleSlot(slotId, 0), scratch);
+        }
+        break;
+      case MoveOp::INT32:
+      case MoveOp::GENERAL:
+        // an non-vfp value
+        if (to.isMemory()) {
+            Register temp = tempReg();
+            masm.ma_ldr(toAddress(to), temp, scratch);
+            masm.ma_str(temp, cycleSlot(0,0), scratch);
+        } else {
+            if (to.reg() == spilledReg_) {
+                // If the destination was spilled, restore it first.
+                masm.ma_ldr(spillSlot(), spilledReg_, scratch);
+                spilledReg_ = InvalidReg;
+            }
+            masm.ma_str(to.reg(), cycleSlot(0,0), scratch);
+        }
+        break;
+      default:
+        MOZ_CRASH("Unexpected move type");
+    }
+}
+
+void
+MoveEmitterARM::completeCycle(const MoveOperand& from, const MoveOperand& to, MoveOp::Type type, uint32_t slotId)
+{
+    // There is some pattern:
+    //   (A -> B)
+    //   (B -> A)
+    //
+    // This case handles (B -> A), which we reach last. We emit a move from the
+    // saved value of B, to A.
+
+    ScratchRegisterScope scratch(masm);
+
+    switch (type) {
+      case MoveOp::FLOAT32:
+        MOZ_ASSERT(!to.isGeneralRegPair());
+        if (to.isMemory()) {
+            ScratchFloat32Scope scratchFloat32(masm);
+            masm.ma_vldr(cycleSlot(slotId, 0), scratchFloat32, scratch);
+            masm.ma_vstr(scratchFloat32, toAddress(to), scratch);
+        } else if (to.isGeneralReg()) {
+            MOZ_ASSERT(type == MoveOp::FLOAT32);
+            masm.ma_ldr(toAddress(from), to.reg(), scratch);
+        } else {
+            uint32_t offset = 0;
+            if ((!from.isMemory()) && from.floatReg().numAlignedAliased() == 1)
+                offset = sizeof(float);
+            masm.ma_vldr(cycleSlot(slotId, offset), to.floatReg(), scratch);
+        }
+        break;
+      case MoveOp::DOUBLE:
+        MOZ_ASSERT(!to.isGeneralReg());
+        if (to.isMemory()) {
+            ScratchDoubleScope scratchDouble(masm);
+            masm.ma_vldr(cycleSlot(slotId, 0), scratchDouble, scratch);
+            masm.ma_vstr(scratchDouble, toAddress(to), scratch);
+        } else if (to.isGeneralRegPair()) {
+            MOZ_ASSERT(type == MoveOp::DOUBLE);
+            ScratchDoubleScope scratchDouble(masm);
+            masm.ma_vldr(toAddress(from), scratchDouble, scratch);
+            masm.ma_vxfer(scratchDouble, to.evenReg(), to.oddReg());
+        } else {
+            uint32_t offset = 0;
+            if ((!from.isMemory()) && from.floatReg().numAlignedAliased() == 1)
+                offset = sizeof(float);
+            masm.ma_vldr(cycleSlot(slotId, offset), to.floatReg(), scratch);
+        }
+        break;
+      case MoveOp::INT32:
+      case MoveOp::GENERAL:
+        MOZ_ASSERT(slotId == 0);
+        if (to.isMemory()) {
+            Register temp = tempReg();
+            masm.ma_ldr(cycleSlot(slotId, 0), temp, scratch);
+            masm.ma_str(temp, toAddress(to), scratch);
+        } else {
+            if (to.reg() == spilledReg_) {
+                // Make sure we don't re-clobber the spilled register later.
+                spilledReg_ = InvalidReg;
+            }
+            masm.ma_ldr(cycleSlot(slotId, 0), to.reg(), scratch);
+        }
+        break;
+      default:
+        MOZ_CRASH("Unexpected move type");
+    }
+}
+
+void
+MoveEmitterARM::emitMove(const MoveOperand& from, const MoveOperand& to)
+{
+    // Register pairs are used to store Double values during calls.
+    MOZ_ASSERT(!from.isGeneralRegPair());
+    MOZ_ASSERT(!to.isGeneralRegPair());
+
+    ScratchRegisterScope scratch(masm);
+
+    if (to.isGeneralReg() && to.reg() == spilledReg_) {
+        // If the destination is the spilled register, make sure we
+        // don't re-clobber its value.
+        spilledReg_ = InvalidReg;
+    }
+
+    if (from.isGeneralReg()) {
+        if (from.reg() == spilledReg_) {
+            // If the source is a register that has been spilled, make sure
+            // to load the source back into that register.
+            masm.ma_ldr(spillSlot(), spilledReg_, scratch);
+            spilledReg_ = InvalidReg;
+        }
+        if (to.isMemoryOrEffectiveAddress())
+            masm.ma_str(from.reg(), toAddress(to), scratch);
+        else
+            masm.ma_mov(from.reg(), to.reg());
+    } else if (to.isGeneralReg()) {
+        MOZ_ASSERT(from.isMemoryOrEffectiveAddress());
+        if (from.isMemory())
+            masm.ma_ldr(toAddress(from), to.reg(), scratch);
+        else
+            masm.ma_add(from.base(), Imm32(from.disp()), to.reg(), scratch);
+    } else {
+        // Memory to memory gpr move.
+        Register reg = tempReg();
+
+        MOZ_ASSERT(from.isMemoryOrEffectiveAddress());
+        if (from.isMemory())
+            masm.ma_ldr(toAddress(from), reg, scratch);
+        else
+            masm.ma_add(from.base(), Imm32(from.disp()), reg, scratch);
+        MOZ_ASSERT(to.base() != reg);
+        masm.ma_str(reg, toAddress(to), scratch);
+    }
+}
+
+void
+MoveEmitterARM::emitFloat32Move(const MoveOperand& from, const MoveOperand& to)
+{
+    // Register pairs are used to store Double values during calls.
+    MOZ_ASSERT(!from.isGeneralRegPair());
+    MOZ_ASSERT(!to.isGeneralRegPair());
+
+    ScratchRegisterScope scratch(masm);
+
+    if (from.isFloatReg()) {
+        if (to.isFloatReg())
+            masm.ma_vmov_f32(from.floatReg(), to.floatReg());
+        else if (to.isGeneralReg())
+            masm.ma_vxfer(from.floatReg(), to.reg());
+        else
+            masm.ma_vstr(VFPRegister(from.floatReg()).singleOverlay(), toAddress(to), scratch);
+    } else if (from.isGeneralReg()) {
+        if (to.isFloatReg()) {
+            masm.ma_vxfer(from.reg(), to.floatReg());
+        } else if (to.isGeneralReg()) {
+            masm.ma_mov(from.reg(), to.reg());
+        } else {
+            masm.ma_str(from.reg(), toAddress(to), scratch);
+        }
+    } else if (to.isFloatReg()) {
+        masm.ma_vldr(toAddress(from), VFPRegister(to.floatReg()).singleOverlay(), scratch);
+    } else if (to.isGeneralReg()) {
+        masm.ma_ldr(toAddress(from), to.reg(), scratch);
+    } else {
+        // Memory to memory move.
+        MOZ_ASSERT(from.isMemory());
+        ScratchFloat32Scope scratchFloat32(masm);
+        masm.ma_vldr(toAddress(from), scratchFloat32, scratch);
+        masm.ma_vstr(scratchFloat32, toAddress(to), scratch);
+    }
+}
+
+void
+MoveEmitterARM::emitDoubleMove(const MoveOperand& from, const MoveOperand& to)
+{
+    // Registers are used to store pointers / int32 / float32 values.
+    MOZ_ASSERT(!from.isGeneralReg());
+    MOZ_ASSERT(!to.isGeneralReg());
+
+    ScratchRegisterScope scratch(masm);
+
+    if (from.isFloatReg()) {
+        if (to.isFloatReg())
+            masm.ma_vmov(from.floatReg(), to.floatReg());
+        else if (to.isGeneralRegPair())
+            masm.ma_vxfer(from.floatReg(), to.evenReg(), to.oddReg());
+        else
+            masm.ma_vstr(from.floatReg(), toAddress(to), scratch);
+    } else if (from.isGeneralRegPair()) {
+        if (to.isFloatReg())
+            masm.ma_vxfer(from.evenReg(), from.oddReg(), to.floatReg());
+        else if (to.isGeneralRegPair()) {
+            MOZ_ASSERT(!from.aliases(to));
+            masm.ma_mov(from.evenReg(), to.evenReg());
+            masm.ma_mov(from.oddReg(), to.oddReg());
+        } else {
+            ScratchDoubleScope scratchDouble(masm);
+            masm.ma_vxfer(from.evenReg(), from.oddReg(), scratchDouble);
+            masm.ma_vstr(scratchDouble, toAddress(to), scratch);
+        }
+    } else if (to.isFloatReg()) {
+        masm.ma_vldr(toAddress(from), to.floatReg(), scratch);
+    } else if (to.isGeneralRegPair()) {
+        MOZ_ASSERT(from.isMemory());
+        Address src = toAddress(from);
+        // Note: We can safely use the MoveOperand's displacement here,
+        // even if the base is SP: MoveEmitter::toOperand adjusts
+        // SP-relative operands by the difference between the current
+        // stack usage and stackAdjust, which emitter.finish() resets to
+        // 0.
+        //
+        // Warning: if the offset isn't within [-255,+255] then this
+        // will assert-fail (or, if non-debug, load the wrong words).
+        // Nothing uses such an offset at the time of this writing.
+        masm.ma_ldrd(EDtrAddr(src.base, EDtrOffImm(src.offset)), to.evenReg(), to.oddReg());
+    } else {
+        // Memory to memory move.
+        MOZ_ASSERT(from.isMemory());
+        ScratchDoubleScope scratchDouble(masm);
+        masm.ma_vldr(toAddress(from), scratchDouble, scratch);
+        masm.ma_vstr(scratchDouble, toAddress(to), scratch);
+    }
+}
+
+void
+MoveEmitterARM::emit(const MoveOp& move)
+{
+    const MoveOperand& from = move.from();
+    const MoveOperand& to = move.to();
+
+    if (move.isCycleEnd() && move.isCycleBegin()) {
+        // A fun consequence of aliased registers is you can have multiple
+        // cycles at once, and one can end exactly where another begins.
+        breakCycle(from, to, move.endCycleType(), move.cycleBeginSlot());
+        completeCycle(from, to, move.type(), move.cycleEndSlot());
+        return;
+    }
+
+    if (move.isCycleEnd()) {
+        MOZ_ASSERT(inCycle_);
+        completeCycle(from, to, move.type(), move.cycleEndSlot());
+        MOZ_ASSERT(inCycle_ > 0);
+        inCycle_--;
+        return;
+    }
+
+    if (move.isCycleBegin()) {
+        breakCycle(from, to, move.endCycleType(), move.cycleBeginSlot());
+        inCycle_++;
+    }
+
+    switch (move.type()) {
+      case MoveOp::FLOAT32:
+        emitFloat32Move(from, to);
+        break;
+      case MoveOp::DOUBLE:
+        emitDoubleMove(from, to);
+        break;
+      case MoveOp::INT32:
+      case MoveOp::GENERAL:
+        emitMove(from, to);
+        break;
+      default:
+        MOZ_CRASH("Unexpected move type");
+    }
+}
+
+void
+MoveEmitterARM::assertDone()
+{
+    MOZ_ASSERT(inCycle_ == 0);
+}
+
+void
+MoveEmitterARM::finish()
+{
+    assertDone();
+
+    if (pushedAtSpill_ != -1 && spilledReg_ != InvalidReg) {
+        ScratchRegisterScope scratch(masm);
+        masm.ma_ldr(spillSlot(), spilledReg_, scratch);
+    }
+    masm.freeStack(masm.framePushed() - pushedAtStart_);
+}
diff --git a/js/src/jit/arm/MoveEmitter-arm.h b/js/src/jit/arm/MoveEmitter-arm.h
new file mode 100644
index 0000000000..70aafbdf6c
--- /dev/null
+++ b/js/src/jit/arm/MoveEmitter-arm.h
@@ -0,0 +1,66 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef jit_arm_MoveEmitter_arm_h
+#define jit_arm_MoveEmitter_arm_h
+
+#include "jit/MacroAssembler.h"
+#include "jit/MoveResolver.h"
+
+namespace js {
+namespace jit {
+
+class MoveEmitterARM
+{
+    uint32_t inCycle_;
+    MacroAssembler& masm;
+
+    // Original stack push value.
+    uint32_t pushedAtStart_;
+
+    // These store stack offsets to spill locations, snapshotting
+    // codegen->framePushed_ at the time they were allocated. They are -1 if no
+    // stack space has been allocated for that particular spill.
+    int32_t pushedAtCycle_;
+    int32_t pushedAtSpill_;
+
+    // These are registers that are available for temporary use. They may be
+    // assigned InvalidReg. If no corresponding spill space has been assigned,
+    // then these registers do not need to be spilled.
+    Register spilledReg_;
+    FloatRegister spilledFloatReg_;
+
+    void assertDone();
+    Register tempReg();
+    FloatRegister tempFloatReg();
+    Address cycleSlot(uint32_t slot, uint32_t subslot) const;
+    Address spillSlot() const;
+    Address toAddress(const MoveOperand& operand) const;
+
+    void emitMove(const MoveOperand& from, const MoveOperand& to);
+    void emitFloat32Move(const MoveOperand& from, const MoveOperand& to);
+    void emitDoubleMove(const MoveOperand& from, const MoveOperand& to);
+    void breakCycle(const MoveOperand& from, const MoveOperand& to,
+                    MoveOp::Type type, uint32_t slot);
+    void completeCycle(const MoveOperand& from, const MoveOperand& to,
+                       MoveOp::Type type, uint32_t slot);
+    void emit(const MoveOp& move);
+
+  public:
+    MoveEmitterARM(MacroAssembler& masm);
+    ~MoveEmitterARM();
+    void emit(const MoveResolver& moves);
+    void finish();
+
+    void setScratchRegister(Register reg) {}
+};
+
+typedef MoveEmitterARM MoveEmitter;
+
+} // namespace jit
+} // namespace js
+
+#endif /* jit_arm_MoveEmitter_arm_h */
diff --git a/js/src/jit/arm/SharedIC-arm.cpp b/js/src/jit/arm/SharedIC-arm.cpp
new file mode 100644
index 0000000000..25c9d4ceec
--- /dev/null
+++ b/js/src/jit/arm/SharedIC-arm.cpp
@@ -0,0 +1,217 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "jit/BaselineCompiler.h"
+#include "jit/BaselineIC.h"
+#include "jit/BaselineJIT.h"
+#include "jit/Linker.h"
+#include "jit/SharedICHelpers.h"
+
+#include "jit/MacroAssembler-inl.h"
+
+using namespace js;
+using namespace js::jit;
+
+namespace js {
+namespace jit {
+
+// ICBinaryArith_Int32
+
+extern "C" {
+    extern MOZ_EXPORT int64_t __aeabi_idivmod(int,int);
+}
+
+bool
+ICBinaryArith_Int32::Compiler::generateStubCode(MacroAssembler& masm)
+{
+    // Guard that R0 is an integer and R1 is an integer.
+    Label failure;
+    masm.branchTestInt32(Assembler::NotEqual, R0, &failure);
+    masm.branchTestInt32(Assembler::NotEqual, R1, &failure);
+
+    // Add R0 and R1. Don't need to explicitly unbox, just use R2's payloadReg.
+    Register scratchReg = R2.payloadReg();
+
+    // DIV and MOD need an extra non-volatile ValueOperand to hold R0.
+    AllocatableGeneralRegisterSet savedRegs(availableGeneralRegs(2));
+    savedRegs.set() = GeneralRegisterSet::Intersect(GeneralRegisterSet::NonVolatile(), savedRegs.set());
+    ValueOperand savedValue = savedRegs.takeAnyValue();
+
+    Label maybeNegZero, revertRegister;
+    switch(op_) {
+      case JSOP_ADD:
+        masm.ma_add(R0.payloadReg(), R1.payloadReg(), scratchReg, SetCC);
+
+        // Just jump to failure on overflow. R0 and R1 are preserved, so we can
+        // just jump to the next stub.
+        masm.j(Assembler::Overflow, &failure);
+
+        // Box the result and return. We know R0.typeReg() already contains the
+        // integer tag, so we just need to move the result value into place.
+        masm.mov(scratchReg, R0.payloadReg());
+        break;
+      case JSOP_SUB:
+        masm.ma_sub(R0.payloadReg(), R1.payloadReg(), scratchReg, SetCC);
+        masm.j(Assembler::Overflow, &failure);
+        masm.mov(scratchReg, R0.payloadReg());
+        break;
+      case JSOP_MUL: {
+        ScratchRegisterScope scratch(masm);
+        Assembler::Condition cond = masm.ma_check_mul(R0.payloadReg(), R1.payloadReg(), scratchReg,
+                                                      scratch, Assembler::Overflow);
+        masm.j(cond, &failure);
+
+        masm.as_cmp(scratchReg, Imm8(0));
+        masm.j(Assembler::Equal, &maybeNegZero);
+
+        masm.mov(scratchReg, R0.payloadReg());
+        break;
+      }
+      case JSOP_DIV:
+      case JSOP_MOD: {
+        // Check for INT_MIN / -1, it results in a double.
+        {
+            ScratchRegisterScope scratch(masm);
+            masm.ma_cmp(R0.payloadReg(), Imm32(INT_MIN), scratch);
+            masm.ma_cmp(R1.payloadReg(), Imm32(-1), scratch, Assembler::Equal);
+            masm.j(Assembler::Equal, &failure);
+        }
+
+        // Check for both division by zero and 0 / X with X < 0 (results in -0).
+        masm.as_cmp(R1.payloadReg(), Imm8(0));
+        masm.as_cmp(R0.payloadReg(), Imm8(0), Assembler::LessThan);
+        masm.j(Assembler::Equal, &failure);
+
+        // The call will preserve registers r4-r11. Save R0 and the link
+        // register.
+        MOZ_ASSERT(R1 == ValueOperand(r5, r4));
+        MOZ_ASSERT(R0 == ValueOperand(r3, r2));
+        masm.moveValue(R0, savedValue);
+
+        masm.setupAlignedABICall();
+        masm.passABIArg(R0.payloadReg());
+        masm.passABIArg(R1.payloadReg());
+        masm.callWithABI(JS_FUNC_TO_DATA_PTR(void*, __aeabi_idivmod));
+
+        // idivmod returns the quotient in r0, and the remainder in r1.
+        if (op_ == JSOP_DIV) {
+            // Result is a double if the remainder != 0.
+            masm.branch32(Assembler::NotEqual, r1, Imm32(0), &revertRegister);
+            masm.tagValue(JSVAL_TYPE_INT32, r0, R0);
+        } else {
+            // If X % Y == 0 and X < 0, the result is -0.
+            Label done;
+            masm.branch32(Assembler::NotEqual, r1, Imm32(0), &done);
+            masm.branch32(Assembler::LessThan, savedValue.payloadReg(), Imm32(0), &revertRegister);
+            masm.bind(&done);
+            masm.tagValue(JSVAL_TYPE_INT32, r1, R0);
+        }
+        break;
+      }
+      case JSOP_BITOR:
+        masm.ma_orr(R1.payloadReg(), R0.payloadReg(), R0.payloadReg());
+        break;
+      case JSOP_BITXOR:
+        masm.ma_eor(R1.payloadReg(), R0.payloadReg(), R0.payloadReg());
+        break;
+      case JSOP_BITAND:
+        masm.ma_and(R1.payloadReg(), R0.payloadReg(), R0.payloadReg());
+        break;
+      case JSOP_LSH:
+        // ARM will happily try to shift by more than 0x1f.
+        masm.as_and(R1.payloadReg(), R1.payloadReg(), Imm8(0x1F));
+        masm.ma_lsl(R1.payloadReg(), R0.payloadReg(), R0.payloadReg());
+        break;
+      case JSOP_RSH:
+        masm.as_and(R1.payloadReg(), R1.payloadReg(), Imm8(0x1F));
+        masm.ma_asr(R1.payloadReg(), R0.payloadReg(), R0.payloadReg());
+        break;
+      case JSOP_URSH:
+        masm.as_and(scratchReg, R1.payloadReg(), Imm8(0x1F));
+        masm.ma_lsr(scratchReg, R0.payloadReg(), scratchReg);
+        masm.as_cmp(scratchReg, Imm8(0));
+        if (allowDouble_) {
+            Label toUint;
+            masm.j(Assembler::LessThan, &toUint);
+
+            // Move result and box for return.
+            masm.mov(scratchReg, R0.payloadReg());
+            EmitReturnFromIC(masm);
+
+            masm.bind(&toUint);
+            ScratchDoubleScope scratchDouble(masm);
+            masm.convertUInt32ToDouble(scratchReg, scratchDouble);
+            masm.boxDouble(scratchDouble, R0);
+        } else {
+            masm.j(Assembler::LessThan, &failure);
+            // Move result for return.
+            masm.mov(scratchReg, R0.payloadReg());
+        }
+        break;
+      default:
+        MOZ_CRASH("Unhandled op for BinaryArith_Int32.");
+    }
+
+    EmitReturnFromIC(masm);
+
+    switch (op_) {
+      case JSOP_MUL:
+        masm.bind(&maybeNegZero);
+
+        // Result is -0 if exactly one of lhs or rhs is negative.
+        masm.ma_cmn(R0.payloadReg(), R1.payloadReg());
+        masm.j(Assembler::Signed, &failure);
+
+        // Result is +0.
+        masm.ma_mov(Imm32(0), R0.payloadReg());
+        EmitReturnFromIC(masm);
+        break;
+      case JSOP_DIV:
+      case JSOP_MOD:
+        masm.bind(&revertRegister);
+        masm.moveValue(savedValue, R0);
+        break;
+      default:
+        break;
+    }
+
+    // Failure case - jump to next stub.
+    masm.bind(&failure);
+    EmitStubGuardFailure(masm);
+
+    return true;
+}
+
+bool
+ICUnaryArith_Int32::Compiler::generateStubCode(MacroAssembler& masm)
+{
+    Label failure;
+    masm.branchTestInt32(Assembler::NotEqual, R0, &failure);
+
+    switch (op) {
+      case JSOP_BITNOT:
+        masm.ma_mvn(R0.payloadReg(), R0.payloadReg());
+        break;
+      case JSOP_NEG:
+        // Guard against 0 and MIN_INT, both result in a double.
+        masm.branchTest32(Assembler::Zero, R0.payloadReg(), Imm32(0x7fffffff), &failure);
+
+        // Compile -x as 0 - x.
+        masm.as_rsb(R0.payloadReg(), R0.payloadReg(), Imm8(0));
+        break;
+      default:
+        MOZ_CRASH("Unexpected op");
+    }
+
+    EmitReturnFromIC(masm);
+
+    masm.bind(&failure);
+    EmitStubGuardFailure(masm);
+    return true;
+}
+
+} // namespace jit
+} // namespace js
diff --git a/js/src/jit/arm/SharedICHelpers-arm.h b/js/src/jit/arm/SharedICHelpers-arm.h
new file mode 100644
index 0000000000..17534adef7
--- /dev/null
+++ b/js/src/jit/arm/SharedICHelpers-arm.h
@@ -0,0 +1,384 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef jit_arm_SharedICHelpers_arm_h
+#define jit_arm_SharedICHelpers_arm_h
+
+#include "jit/BaselineFrame.h"
+#include "jit/BaselineIC.h"
+#include "jit/MacroAssembler.h"
+#include "jit/SharedICRegisters.h"
+
+namespace js {
+namespace jit {
+
+// Distance from sp to the top Value inside an IC stub (no return address on the stack on ARM).
+static const size_t ICStackValueOffset = 0;
+
+inline void
+EmitRestoreTailCallReg(MacroAssembler& masm)
+{
+    // No-op on ARM because link register is always holding the return address.
+}
+
+inline void
+EmitRepushTailCallReg(MacroAssembler& masm)
+{
+    // No-op on ARM because link register is always holding the return address.
+}
+
+inline void
+EmitCallIC(CodeOffset* patchOffset, MacroAssembler& masm)
+{
+    // Move ICEntry offset into ICStubReg
+    CodeOffset offset = masm.movWithPatch(ImmWord(-1), ICStubReg);
+    *patchOffset = offset;
+
+    // Load stub pointer into ICStubReg
+    masm.loadPtr(Address(ICStubReg, ICEntry::offsetOfFirstStub()), ICStubReg);
+
+    // Load stubcode pointer from BaselineStubEntry.
+    // R2 won't be active when we call ICs, so we can use r0.
+    MOZ_ASSERT(R2 == ValueOperand(r1, r0));
+    masm.loadPtr(Address(ICStubReg, ICStub::offsetOfStubCode()), r0);
+
+    // Call the stubcode via a direct branch-and-link.
+    masm.ma_blx(r0);
+}
+
+inline void
+EmitEnterTypeMonitorIC(MacroAssembler& masm,
+                       size_t monitorStubOffset = ICMonitoredStub::offsetOfFirstMonitorStub())
+{
+    // This is expected to be called from within an IC, when ICStubReg is
+    // properly initialized to point to the stub.
+    masm.loadPtr(Address(ICStubReg, (uint32_t) monitorStubOffset), ICStubReg);
+
+    // Load stubcode pointer from BaselineStubEntry.
+    // R2 won't be active when we call ICs, so we can use r0.
+    MOZ_ASSERT(R2 == ValueOperand(r1, r0));
+    masm.loadPtr(Address(ICStubReg, ICStub::offsetOfStubCode()), r0);
+
+    // Jump to the stubcode.
+    masm.branch(r0);
+}
+
+inline void
+EmitReturnFromIC(MacroAssembler& masm)
+{
+    masm.ma_mov(lr, pc);
+}
+
+inline void
+EmitChangeICReturnAddress(MacroAssembler& masm, Register reg)
+{
+    masm.ma_mov(reg, lr);
+}
+
+inline void
+EmitBaselineTailCallVM(JitCode* target, MacroAssembler& masm, uint32_t argSize)
+{
+    // We assume during this that R0 and R1 have been pushed, and that R2 is
+    // unused.
+    MOZ_ASSERT(R2 == ValueOperand(r1, r0));
+
+    // Compute frame size.
+    masm.movePtr(BaselineFrameReg, r0);
+    masm.as_add(r0, r0, Imm8(BaselineFrame::FramePointerOffset));
+    masm.ma_sub(BaselineStackReg, r0);
+
+    // Store frame size without VMFunction arguments for GC marking.
+    {
+        ScratchRegisterScope scratch(masm);
+        masm.ma_sub(r0, Imm32(argSize), r1, scratch);
+    }
+    masm.store32(r1, Address(BaselineFrameReg, BaselineFrame::reverseOffsetOfFrameSize()));
+
+    // Push frame descriptor and perform the tail call.
+    // ICTailCallReg (lr) already contains the return address (as we keep
+    // it there through the stub calls), but the VMWrapper code being called
+    // expects the return address to also be pushed on the stack.
+    MOZ_ASSERT(ICTailCallReg == lr);
+    masm.makeFrameDescriptor(r0, JitFrame_BaselineJS, ExitFrameLayout::Size());
+    masm.push(r0);
+    masm.push(lr);
+    masm.branch(target);
+}
+
+inline void
+EmitIonTailCallVM(JitCode* target, MacroAssembler& masm, uint32_t stackSize)
+{
+    // We assume during this that R0 and R1 have been pushed, and that R2 is
+    // unused.
+    MOZ_ASSERT(R2 == ValueOperand(r1, r0));
+
+    masm.loadPtr(Address(sp, stackSize), r0);
+    masm.rshiftPtr(Imm32(FRAMESIZE_SHIFT), r0);
+    masm.add32(Imm32(stackSize + JitStubFrameLayout::Size() - sizeof(intptr_t)), r0);
+
+    // Push frame descriptor and perform the tail call.
+    // ICTailCallReg (lr) already contains the return address (as we keep
+    // it there through the stub calls), but the VMWrapper code being called
+    // expects the return address to also be pushed on the stack.
+    MOZ_ASSERT(ICTailCallReg == lr);
+    masm.makeFrameDescriptor(r0, JitFrame_IonJS, ExitFrameLayout::Size());
+    masm.push(r0);
+    masm.push(lr);
+    masm.branch(target);
+}
+
+inline void
+EmitBaselineCreateStubFrameDescriptor(MacroAssembler& masm, Register reg, uint32_t headerSize)
+{
+    // Compute stub frame size. We have to add two pointers: the stub reg and
+    // previous frame pointer pushed by EmitEnterStubFrame.
+    masm.mov(BaselineFrameReg, reg);
+    masm.as_add(reg, reg, Imm8(sizeof(void*) * 2));
+    masm.ma_sub(BaselineStackReg, reg);
+
+    masm.makeFrameDescriptor(reg, JitFrame_BaselineStub, headerSize);
+}
+
+inline void
+EmitBaselineCallVM(JitCode* target, MacroAssembler& masm)
+{
+    EmitBaselineCreateStubFrameDescriptor(masm, r0, ExitFrameLayout::Size());
+    masm.push(r0);
+    masm.call(target);
+}
+
+inline void
+EmitIonCallVM(JitCode* target, size_t stackSlots, MacroAssembler& masm)
+{
+    uint32_t descriptor = MakeFrameDescriptor(masm.framePushed(), JitFrame_IonStub,
+                                              ExitFrameLayout::Size());
+    masm.Push(Imm32(descriptor));
+    masm.callJit(target);
+
+    // Remove rest of the frame left on the stack. We remove the return address
+    // which is implicitly popped when returning.
+    size_t framePop = sizeof(ExitFrameLayout) - sizeof(void*);
+
+    // Pop arguments from framePushed.
+    masm.implicitPop(stackSlots * sizeof(void*) + framePop);
+}
+
+// Size of vales pushed by EmitEnterStubFrame.
+static const uint32_t STUB_FRAME_SIZE = 4 * sizeof(void*);
+static const uint32_t STUB_FRAME_SAVED_STUB_OFFSET = sizeof(void*);
+
+inline void
+EmitBaselineEnterStubFrame(MacroAssembler& masm, Register scratch)
+{
+    MOZ_ASSERT(scratch != ICTailCallReg);
+
+    // Compute frame size.
+    masm.mov(BaselineFrameReg, scratch);
+    masm.as_add(scratch, scratch, Imm8(BaselineFrame::FramePointerOffset));
+    masm.ma_sub(BaselineStackReg, scratch);
+
+    masm.store32(scratch, Address(BaselineFrameReg, BaselineFrame::reverseOffsetOfFrameSize()));
+
+    // Note: when making changes here, don't forget to update STUB_FRAME_SIZE if
+    // needed.
+
+    // Push frame descriptor and return address.
+    masm.makeFrameDescriptor(scratch, JitFrame_BaselineJS, BaselineStubFrameLayout::Size());
+    masm.Push(scratch);
+    masm.Push(ICTailCallReg);
+
+    // Save old frame pointer, stack pointer and stub reg.
+    masm.Push(ICStubReg);
+    masm.Push(BaselineFrameReg);
+    masm.mov(BaselineStackReg, BaselineFrameReg);
+
+    // We pushed 4 words, so the stack is still aligned to 8 bytes.
+    masm.checkStackAlignment();
+}
+
+inline void
+EmitIonEnterStubFrame(MacroAssembler& masm, Register scratch)
+{
+    MOZ_ASSERT(ICTailCallReg == lr);
+
+    // In arm the link register contains the return address,
+    // but in jit frames we expect it to be on the stack. As a result
+    // push the link register (which is actually part of the previous frame.
+    // Therefore using push instead of Push).
+    masm.push(ICTailCallReg);
+
+    masm.Push(ICStubReg);
+}
+
+inline void
+EmitBaselineLeaveStubFrame(MacroAssembler& masm, bool calledIntoIon = false)
+{
+    ScratchRegisterScope scratch(masm);
+
+    // Ion frames do not save and restore the frame pointer. If we called into
+    // Ion, we have to restore the stack pointer from the frame descriptor. If
+    // we performed a VM call, the descriptor has been popped already so in that
+    // case we use the frame pointer.
+    if (calledIntoIon) {
+        masm.Pop(scratch);
+        masm.rshiftPtr(Imm32(FRAMESIZE_SHIFT), scratch);
+        masm.add32(scratch, BaselineStackReg);
+    } else {
+        masm.mov(BaselineFrameReg, BaselineStackReg);
+    }
+
+    masm.Pop(BaselineFrameReg);
+    masm.Pop(ICStubReg);
+
+    // Load the return address.
+    masm.Pop(ICTailCallReg);
+
+    // Discard the frame descriptor.
+    masm.Pop(scratch);
+}
+
+inline void
+EmitIonLeaveStubFrame(MacroAssembler& masm)
+{
+    masm.Pop(ICStubReg);
+    masm.pop(ICTailCallReg); // See EmitIonEnterStubFrame for explanation on pop/Pop.
+}
+
+inline void
+EmitStowICValues(MacroAssembler& masm, int values)
+{
+    MOZ_ASSERT(values >= 0 && values <= 2);
+    switch(values) {
+      case 1:
+        // Stow R0.
+        masm.Push(R0);
+        break;
+      case 2:
+        // Stow R0 and R1.
+        masm.Push(R0);
+        masm.Push(R1);
+        break;
+    }
+}
+
+inline void
+EmitUnstowICValues(MacroAssembler& masm, int values, bool discard = false)
+{
+    MOZ_ASSERT(values >= 0 && values <= 2);
+    switch(values) {
+      case 1:
+        // Unstow R0.
+        if (discard)
+            masm.addPtr(Imm32(sizeof(Value)), BaselineStackReg);
+        else
+            masm.popValue(R0);
+        break;
+      case 2:
+        // Unstow R0 and R1.
+        if (discard) {
+            masm.addPtr(Imm32(sizeof(Value) * 2), BaselineStackReg);
+        } else {
+            masm.popValue(R1);
+            masm.popValue(R0);
+        }
+        break;
+    }
+    masm.adjustFrame(-values * sizeof(Value));
+}
+
+inline void
+EmitCallTypeUpdateIC(MacroAssembler& masm, JitCode* code, uint32_t objectOffset)
+{
+    MOZ_ASSERT(R2 == ValueOperand(r1, r0));
+
+    // R0 contains the value that needs to be typechecked. The object we're
+    // updating is a boxed Value on the stack, at offset objectOffset from esp,
+    // excluding the return address.
+
+    // Save the current ICStubReg to stack, as well as the TailCallReg,
+    // since on ARM, the LR is live.
+    masm.push(ICStubReg);
+    masm.push(ICTailCallReg);
+
+    // This is expected to be called from within an IC, when ICStubReg is
+    // properly initialized to point to the stub.
+    masm.loadPtr(Address(ICStubReg, ICUpdatedStub::offsetOfFirstUpdateStub()),
+                 ICStubReg);
+
+    // TODO: Change r0 uses below to use masm's configurable scratch register instead.
+
+    // Load stubcode pointer from ICStubReg into ICTailCallReg.
+    masm.loadPtr(Address(ICStubReg, ICStub::offsetOfStubCode()), r0);
+
+    // Call the stubcode.
+    masm.ma_blx(r0);
+
+    // Restore the old stub reg and tailcall reg.
+    masm.pop(ICTailCallReg);
+    masm.pop(ICStubReg);
+
+    // The update IC will store 0 or 1 in R1.scratchReg() reflecting if the
+    // value in R0 type-checked properly or not.
+    Label success;
+    masm.cmp32(R1.scratchReg(), Imm32(1));
+    masm.j(Assembler::Equal, &success);
+
+    // If the IC failed, then call the update fallback function.
+    EmitBaselineEnterStubFrame(masm, R1.scratchReg());
+
+    masm.loadValue(Address(BaselineStackReg, STUB_FRAME_SIZE + objectOffset), R1);
+
+    masm.Push(R0);
+    masm.Push(R1);
+    masm.Push(ICStubReg);
+
+    // Load previous frame pointer, push BaselineFrame*.
+    masm.loadPtr(Address(BaselineFrameReg, 0), R0.scratchReg());
+    masm.pushBaselineFramePtr(R0.scratchReg(), R0.scratchReg());
+
+    EmitBaselineCallVM(code, masm);
+    EmitBaselineLeaveStubFrame(masm);
+
+    // Success at end.
+    masm.bind(&success);
+}
+
+template <typename AddrType>
+inline void
+EmitPreBarrier(MacroAssembler& masm, const AddrType& addr, MIRType type)
+{
+    // On ARM, lr is clobbered by patchableCallPreBarrier. Save it first.
+    masm.push(lr);
+    masm.patchableCallPreBarrier(addr, type);
+    masm.pop(lr);
+}
+
+inline void
+EmitStubGuardFailure(MacroAssembler& masm)
+{
+    MOZ_ASSERT(R2 == ValueOperand(r1, r0));
+
+    // NOTE: This routine assumes that the stub guard code left the stack in the
+    // same state it was in when it was entered.
+
+    // BaselineStubEntry points to the current stub.
+
+    // Load next stub into ICStubReg.
+    masm.loadPtr(Address(ICStubReg, ICStub::offsetOfNext()), ICStubReg);
+
+    // Load stubcode pointer from BaselineStubEntry into scratch register.
+    masm.loadPtr(Address(ICStubReg, ICStub::offsetOfStubCode()), r0);
+
+    // Return address is already loaded, just jump to the next stubcode.
+    MOZ_ASSERT(ICTailCallReg == lr);
+    masm.branch(r0);
+}
+
+
+} // namespace jit
+} // namespace js
+
+#endif /* jit_arm_SharedICHelpers_arm_h */
diff --git a/js/src/jit/arm/SharedICRegisters-arm.h b/js/src/jit/arm/SharedICRegisters-arm.h
new file mode 100644
index 0000000000..144a3bd504
--- /dev/null
+++ b/js/src/jit/arm/SharedICRegisters-arm.h
@@ -0,0 +1,54 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef jit_arm_SharedICRegisters_arm_h
+#define jit_arm_SharedICRegisters_arm_h
+
+#include "jit/MacroAssembler.h"
+
+namespace js {
+namespace jit {
+
+// r15 = program-counter
+// r14 = link-register
+
+// r13 = stack-pointer
+// r11 = frame-pointer
+static constexpr Register BaselineFrameReg = r11;
+static constexpr Register BaselineStackReg = sp;
+
+// ValueOperands R0, R1, and R2.
+// R0 == JSReturnReg, and R2 uses registers not preserved across calls. R1 value
+// should be preserved across calls.
+static constexpr ValueOperand R0(r3, r2);
+static constexpr ValueOperand R1(r5, r4);
+static constexpr ValueOperand R2(r1, r0);
+
+// ICTailCallReg and ICStubReg
+// These use registers that are not preserved across calls.
+static constexpr Register ICTailCallReg = r14;
+static constexpr Register ICStubReg     = r9;
+
+static constexpr Register ExtractTemp0        = InvalidReg;
+static constexpr Register ExtractTemp1        = InvalidReg;
+
+// Register used internally by MacroAssemblerARM.
+static constexpr Register BaselineSecondScratchReg = r6;
+
+// R7 - R9 are generally available for use within stubcode.
+
+// Note that ICTailCallReg is actually just the link register. In ARM code
+// emission, we do not clobber ICTailCallReg since we keep the return
+// address for calls there.
+
+// FloatReg0 must be equal to ReturnFloatReg.
+static constexpr FloatRegister FloatReg0      = d0;
+static constexpr FloatRegister FloatReg1      = d1;
+
+} // namespace jit
+} // namespace js
+
+#endif /* jit_arm_SharedICRegisters_arm_h */
diff --git a/js/src/jit/arm/Simulator-arm.cpp b/js/src/jit/arm/Simulator-arm.cpp
new file mode 100644
index 0000000000..2b295212a5
--- /dev/null
+++ b/js/src/jit/arm/Simulator-arm.cpp
@@ -0,0 +1,4941 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+// Copyright 2012 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#include "jit/arm/Simulator-arm.h"
+
+#include "mozilla/Casting.h"
+#include "mozilla/DebugOnly.h"
+#include "mozilla/FloatingPoint.h"
+#include "mozilla/Likely.h"
+#include "mozilla/MathAlgorithms.h"
+#include "mozilla/SizePrintfMacros.h"
+
+#include "jit/arm/Assembler-arm.h"
+#include "jit/arm/disasm/Constants-arm.h"
+#include "jit/AtomicOperations.h"
+#include "threading/LockGuard.h"
+#include "vm/Runtime.h"
+#include "vm/SharedMem.h"
+#include "wasm/WasmInstance.h"
+#include "wasm/WasmSignalHandlers.h"
+
+extern "C" {
+
+int64_t
+__aeabi_idivmod(int x, int y)
+{
+    uint32_t lo = uint32_t(x / y);
+    uint32_t hi = uint32_t(x % y);
+    return (int64_t(hi) << 32) | lo;
+}
+
+int64_t
+__aeabi_uidivmod(int x, int y)
+{
+    uint32_t lo = uint32_t(x) / uint32_t(y);
+    uint32_t hi = uint32_t(x) % uint32_t(y);
+    return (int64_t(hi) << 32) | lo;
+}
+}
+
+namespace js {
+namespace jit {
+
+// Load/store multiple addressing mode.
+enum BlockAddrMode {
+    // Alias modes for comparison when writeback does not matter.
+    da_x         = (0|0|0) << 21,  // Decrement after.
+    ia_x         = (0|4|0) << 21,  // Increment after.
+    db_x         = (8|0|0) << 21,  // Decrement before.
+    ib_x         = (8|4|0) << 21,  // Increment before.
+};
+
+// Type of VFP register. Determines register encoding.
+enum VFPRegPrecision {
+    kSinglePrecision = 0,
+    kDoublePrecision = 1
+};
+
+enum NeonListType {
+    nlt_1 = 0x7,
+    nlt_2 = 0xA,
+    nlt_3 = 0x6,
+    nlt_4 = 0x2
+};
+
+// Supervisor Call (svc) specific support.
+
+// Special Software Interrupt codes when used in the presence of the ARM
+// simulator.
+// svc (formerly swi) provides a 24bit immediate value. Use bits 22:0 for
+// standard SoftwareInterrupCode. Bit 23 is reserved for the stop feature.
+enum SoftwareInterruptCodes {
+    kCallRtRedirected = 0x10,  // Transition to C code.
+    kBreakpoint= 0x20, // Breakpoint.
+    kStopCode = 1 << 23 // Stop.
+};
+
+const uint32_t kStopCodeMask = kStopCode - 1;
+const uint32_t kMaxStopCode = kStopCode - 1;
+
+// -----------------------------------------------------------------------------
+// Instruction abstraction.
+
+// The class Instruction enables access to individual fields defined in the ARM
+// architecture instruction set encoding as described in figure A3-1.
+// Note that the Assembler uses typedef int32_t Instr.
+//
+// Example: Test whether the instruction at ptr does set the condition code
+// bits.
+//
+// bool InstructionSetsConditionCodes(byte* ptr) {
+//   Instruction* instr = Instruction::At(ptr);
+//   int type = instr->TypeValue();
+//   return ((type == 0) || (type == 1)) && instr->hasS();
+// }
+//
+class SimInstruction {
+  public:
+    enum {
+        kInstrSize = 4,
+        kPCReadOffset = 8
+    };
+
+    // Get the raw instruction bits.
+    inline Instr instructionBits() const {
+        return *reinterpret_cast<const Instr*>(this);
+    }
+
+    // Set the raw instruction bits to value.
+    inline void setInstructionBits(Instr value) {
+        *reinterpret_cast<Instr*>(this) = value;
+    }
+
+    // Read one particular bit out of the instruction bits.
+    inline int bit(int nr) const {
+        return (instructionBits() >> nr) & 1;
+    }
+
+    // Read a bit field's value out of the instruction bits.
+    inline int bits(int hi, int lo) const {
+        return (instructionBits() >> lo) & ((2 << (hi - lo)) - 1);
+    }
+
+    // Read a bit field out of the instruction bits.
+    inline int bitField(int hi, int lo) const {
+        return instructionBits() & (((2 << (hi - lo)) - 1) << lo);
+    }
+
+    // Accessors for the different named fields used in the ARM encoding.
+    // The naming of these accessor corresponds to figure A3-1.
+    //
+    // Two kind of accessors are declared:
+    // - <Name>Field() will return the raw field, i.e. the field's bits at their
+    //   original place in the instruction encoding.
+    //   e.g. if instr is the 'addgt r0, r1, r2' instruction, encoded as
+    //   0xC0810002 conditionField(instr) will return 0xC0000000.
+    // - <Name>Value() will return the field value, shifted back to bit 0.
+    //   e.g. if instr is the 'addgt r0, r1, r2' instruction, encoded as
+    //   0xC0810002 conditionField(instr) will return 0xC.
+
+    // Generally applicable fields
+    inline Assembler::ARMCondition conditionField() const {
+        return static_cast<Assembler::ARMCondition>(bitField(31, 28));
+    }
+    inline int typeValue() const { return bits(27, 25); }
+    inline int specialValue() const { return bits(27, 23); }
+
+    inline int rnValue() const { return bits(19, 16); }
+    inline int rdValue() const { return bits(15, 12); }
+
+    inline int coprocessorValue() const { return bits(11, 8); }
+
+    // Support for VFP.
+    // Vn(19-16) | Vd(15-12) |  Vm(3-0)
+    inline int vnValue() const { return bits(19, 16); }
+    inline int vmValue() const { return bits(3, 0); }
+    inline int vdValue() const { return bits(15, 12); }
+    inline int nValue() const { return bit(7); }
+    inline int mValue() const { return bit(5); }
+    inline int dValue() const { return bit(22); }
+    inline int rtValue() const { return bits(15, 12); }
+    inline int pValue() const { return bit(24); }
+    inline int uValue() const { return bit(23); }
+    inline int opc1Value() const { return (bit(23) << 2) | bits(21, 20); }
+    inline int opc2Value() const { return bits(19, 16); }
+    inline int opc3Value() const { return bits(7, 6); }
+    inline int szValue() const { return bit(8); }
+    inline int VLValue() const { return bit(20); }
+    inline int VCValue() const { return bit(8); }
+    inline int VAValue() const { return bits(23, 21); }
+    inline int VBValue() const { return bits(6, 5); }
+    inline int VFPNRegValue(VFPRegPrecision pre) { return VFPGlueRegValue(pre, 16, 7); }
+    inline int VFPMRegValue(VFPRegPrecision pre) { return VFPGlueRegValue(pre, 0, 5); }
+    inline int VFPDRegValue(VFPRegPrecision pre) { return VFPGlueRegValue(pre, 12, 22); }
+
+    // Fields used in Data processing instructions.
+    inline int opcodeValue() const { return static_cast<ALUOp>(bits(24, 21)); }
+    inline ALUOp opcodeField() const { return static_cast<ALUOp>(bitField(24, 21)); }
+    inline int sValue() const { return bit(20); }
+
+    // With register.
+    inline int rmValue() const { return bits(3, 0); }
+    inline ShiftType shifttypeValue() const { return static_cast<ShiftType>(bits(6, 5)); }
+    inline int rsValue() const { return bits(11, 8); }
+    inline int shiftAmountValue() const { return bits(11, 7); }
+
+    // With immediate.
+    inline int rotateValue() const { return bits(11, 8); }
+    inline int immed8Value() const { return bits(7, 0); }
+    inline int immed4Value() const { return bits(19, 16); }
+    inline int immedMovwMovtValue() const { return immed4Value() << 12 | offset12Value(); }
+
+    // Fields used in Load/Store instructions.
+    inline int PUValue() const { return bits(24, 23); }
+    inline int PUField() const { return bitField(24, 23); }
+    inline int bValue() const { return bit(22); }
+    inline int wValue() const { return bit(21); }
+    inline int lValue() const { return bit(20); }
+
+    // With register uses same fields as Data processing instructions above with
+    // immediate.
+    inline int offset12Value() const { return bits(11, 0); }
+
+    // Multiple.
+    inline int rlistValue() const { return bits(15, 0); }
+
+    // Extra loads and stores.
+    inline int signValue() const { return bit(6); }
+    inline int hValue() const { return bit(5); }
+    inline int immedHValue() const { return bits(11, 8); }
+    inline int immedLValue() const { return bits(3, 0); }
+
+    // Fields used in Branch instructions.
+    inline int linkValue() const { return bit(24); }
+    inline int sImmed24Value() const { return ((instructionBits() << 8) >> 8); }
+
+    // Fields used in Software interrupt instructions.
+    inline SoftwareInterruptCodes svcValue() const {
+        return static_cast<SoftwareInterruptCodes>(bits(23, 0));
+    }
+
+    // Test for special encodings of type 0 instructions (extra loads and
+    // stores, as well as multiplications).
+    inline bool isSpecialType0() const { return (bit(7) == 1) && (bit(4) == 1); }
+
+    // Test for miscellaneous instructions encodings of type 0 instructions.
+    inline bool isMiscType0() const {
+        return bit(24) == 1 && bit(23) == 0 && bit(20) == 0 && (bit(7) == 0);
+    }
+
+    // Test for a nop instruction, which falls under type 1.
+    inline bool isNopType1() const { return bits(24, 0) == 0x0120F000; }
+
+    // Test for a stop instruction.
+    inline bool isStop() const {
+        return typeValue() == 7 && bit(24) == 1 && svcValue() >= kStopCode;
+    }
+
+    // Special accessors that test for existence of a value.
+    inline bool hasS()    const { return sValue() == 1; }
+    inline bool hasB()    const { return bValue() == 1; }
+    inline bool hasW()    const { return wValue() == 1; }
+    inline bool hasL()    const { return lValue() == 1; }
+    inline bool hasU()    const { return uValue() == 1; }
+    inline bool hasSign() const { return signValue() == 1; }
+    inline bool hasH()    const { return hValue() == 1; }
+    inline bool hasLink() const { return linkValue() == 1; }
+
+    // Decoding the double immediate in the vmov instruction.
+    double doubleImmedVmov() const;
+    // Decoding the float32 immediate in the vmov.f32 instruction.
+    float float32ImmedVmov() const;
+
+  private:
+    // Join split register codes, depending on single or double precision.
+    // four_bit is the position of the least-significant bit of the four
+    // bit specifier. one_bit is the position of the additional single bit
+    // specifier.
+    inline int VFPGlueRegValue(VFPRegPrecision pre, int four_bit, int one_bit) {
+        if (pre == kSinglePrecision)
+            return (bits(four_bit + 3, four_bit) << 1) | bit(one_bit);
+        return (bit(one_bit) << 4) | bits(four_bit + 3, four_bit);
+    }
+
+    SimInstruction() = delete;
+    SimInstruction(const SimInstruction& other) = delete;
+    void operator=(const SimInstruction& other) = delete;
+};
+
+double
+SimInstruction::doubleImmedVmov() const
+{
+    // Reconstruct a double from the immediate encoded in the vmov instruction.
+    //
+    //   instruction: [xxxxxxxx,xxxxabcd,xxxxxxxx,xxxxefgh]
+    //   double: [aBbbbbbb,bbcdefgh,00000000,00000000,
+    //            00000000,00000000,00000000,00000000]
+    //
+    // where B = ~b. Only the high 16 bits are affected.
+    uint64_t high16;
+    high16  = (bits(17, 16) << 4) | bits(3, 0);   // xxxxxxxx,xxcdefgh.
+    high16 |= (0xff * bit(18)) << 6;              // xxbbbbbb,bbxxxxxx.
+    high16 |= (bit(18) ^ 1) << 14;                // xBxxxxxx,xxxxxxxx.
+    high16 |= bit(19) << 15;                      // axxxxxxx,xxxxxxxx.
+
+    uint64_t imm = high16 << 48;
+    return mozilla::BitwiseCast<double>(imm);
+}
+
+float
+SimInstruction::float32ImmedVmov() const
+{
+    // Reconstruct a float32 from the immediate encoded in the vmov instruction.
+    //
+    //   instruction: [xxxxxxxx,xxxxabcd,xxxxxxxx,xxxxefgh]
+    //   float32: [aBbbbbbc, defgh000, 00000000, 00000000]
+    //
+    // where B = ~b. Only the high 16 bits are affected.
+    uint32_t imm;
+    imm  = (bits(17, 16) << 23) | (bits(3, 0) << 19); // xxxxxxxc,defgh000.0.0
+    imm |= (0x1f * bit(18)) << 25;                    // xxbbbbbx,xxxxxxxx.0.0
+    imm |= (bit(18) ^ 1) << 30;                       // xBxxxxxx,xxxxxxxx.0.0
+    imm |= bit(19) << 31;                             // axxxxxxx,xxxxxxxx.0.0
+
+    return mozilla::BitwiseCast<float>(imm);
+}
+
+class CachePage
+{
+  public:
+    static const int LINE_VALID = 0;
+    static const int LINE_INVALID = 1;
+    static const int kPageShift = 12;
+    static const int kPageSize = 1 << kPageShift;
+    static const int kPageMask = kPageSize - 1;
+    static const int kLineShift = 2;  // The cache line is only 4 bytes right now.
+    static const int kLineLength = 1 << kLineShift;
+    static const int kLineMask = kLineLength - 1;
+
+    CachePage() {
+        memset(&validity_map_, LINE_INVALID, sizeof(validity_map_));
+    }
+    char* validityByte(int offset) {
+        return &validity_map_[offset >> kLineShift];
+    }
+    char* cachedData(int offset) {
+        return &data_[offset];
+    }
+
+  private:
+    char data_[kPageSize];   // The cached data.
+    static const int kValidityMapSize = kPageSize >> kLineShift;
+    char validity_map_[kValidityMapSize];  // One byte per line.
+};
+
+// Protects the icache() and redirection() properties of the
+// Simulator.
+class AutoLockSimulatorCache : public LockGuard<Mutex>
+{
+    using Base = LockGuard<Mutex>;
+
+  public:
+    explicit AutoLockSimulatorCache(Simulator* sim)
+      : Base(sim->cacheLock_)
+      , sim_(sim)
+    {
+        MOZ_ASSERT(sim_->cacheLockHolder_.isNothing());
+#ifdef DEBUG
+        sim_->cacheLockHolder_ = mozilla::Some(ThisThread::GetId());
+#endif
+    }
+
+    ~AutoLockSimulatorCache() {
+        MOZ_ASSERT(sim_->cacheLockHolder_.isSome());
+#ifdef DEBUG
+        sim_->cacheLockHolder_.reset();
+#endif
+    }
+
+  private:
+    Simulator* const sim_;
+};
+
+bool Simulator::ICacheCheckingEnabled = false;
+
+int64_t Simulator::StopSimAt = -1L;
+
+Simulator*
+Simulator::Create(JSContext* cx)
+{
+    Simulator* sim = js_new<Simulator>(cx);
+    if (!sim)
+        return nullptr;
+
+    if (!sim->init()) {
+        js_delete(sim);
+        return nullptr;
+    }
+
+    if (getenv("ARM_SIM_ICACHE_CHECKS"))
+        Simulator::ICacheCheckingEnabled = true;
+
+    char* stopAtStr = getenv("ARM_SIM_STOP_AT");
+    int64_t stopAt;
+    if (stopAtStr && sscanf(stopAtStr, "%lld", &stopAt) == 1) {
+        fprintf(stderr, "\nStopping simulation at icount %lld\n", stopAt);
+        Simulator::StopSimAt = stopAt;
+    }
+
+    return sim;
+}
+
+void
+Simulator::Destroy(Simulator* sim)
+{
+    js_delete(sim);
+}
+
+void
+Simulator::disassemble(SimInstruction* instr, size_t n)
+{
+    disasm::NameConverter converter;
+    disasm::Disassembler dasm(converter);
+    disasm::EmbeddedVector<char, disasm::ReasonableBufferSize> buffer;
+    while (n-- > 0) {
+        dasm.InstructionDecode(buffer,
+                               reinterpret_cast<uint8_t*>(instr));
+        printf("  0x%08x  %s\n", uint32_t(instr), buffer.start());
+        instr = reinterpret_cast<SimInstruction*>(reinterpret_cast<uint8_t*>(instr) + 4);
+    }
+}
+
+void
+Simulator::disasm(SimInstruction* instr)
+{
+    disassemble(instr, 1);
+}
+
+void
+Simulator::disasm(SimInstruction* instr, size_t n)
+{
+    disassemble(instr, n);
+}
+
+void
+Simulator::disasm(SimInstruction* instr, size_t m, size_t n)
+{
+    disassemble(reinterpret_cast<SimInstruction*>(reinterpret_cast<uint8_t*>(instr)-m*4), n);
+}
+
+// The ArmDebugger class is used by the simulator while debugging simulated ARM
+// code.
+class ArmDebugger {
+  public:
+    explicit ArmDebugger(Simulator* sim) : sim_(sim) { }
+
+    void stop(SimInstruction* instr);
+    void debug();
+
+  private:
+    static const Instr kBreakpointInstr = (Assembler::AL | (7 * (1 << 25)) | (1* (1 << 24)) | kBreakpoint);
+    static const Instr kNopInstr = (Assembler::AL | (13 * (1 << 21)));
+
+    Simulator* sim_;
+
+    int32_t getRegisterValue(int regnum);
+    double getRegisterPairDoubleValue(int regnum);
+    void getVFPDoubleRegisterValue(int regnum, double* value);
+    bool getValue(const char* desc, int32_t* value);
+    bool getVFPDoubleValue(const char* desc, double* value);
+
+    // Set or delete a breakpoint. Returns true if successful.
+    bool setBreakpoint(SimInstruction* breakpc);
+    bool deleteBreakpoint(SimInstruction* breakpc);
+
+    // Undo and redo all breakpoints. This is needed to bracket disassembly and
+    // execution to skip past breakpoints when run from the debugger.
+    void undoBreakpoints();
+    void redoBreakpoints();
+};
+
+void
+ArmDebugger::stop(SimInstruction * instr)
+{
+    // Get the stop code.
+    uint32_t code = instr->svcValue() & kStopCodeMask;
+    // Retrieve the encoded address, which comes just after this stop.
+    char* msg = *reinterpret_cast<char**>(sim_->get_pc()
+                                          + SimInstruction::kInstrSize);
+    // Update this stop description.
+    if (sim_->isWatchedStop(code) && !sim_->watched_stops_[code].desc) {
+        sim_->watched_stops_[code].desc = msg;
+    }
+    // Print the stop message and code if it is not the default code.
+    if (code != kMaxStopCode) {
+        printf("Simulator hit stop %u: %s\n", code, msg);
+    } else {
+        printf("Simulator hit %s\n", msg);
+    }
+    sim_->set_pc(sim_->get_pc() + 2 * SimInstruction::kInstrSize);
+    debug();
+}
+
+int32_t
+ArmDebugger::getRegisterValue(int regnum)
+{
+    if (regnum == Registers::pc)
+        return sim_->get_pc();
+    return sim_->get_register(regnum);
+}
+
+double
+ArmDebugger::getRegisterPairDoubleValue(int regnum)
+{
+    return sim_->get_double_from_register_pair(regnum);
+}
+
+void
+ArmDebugger::getVFPDoubleRegisterValue(int regnum, double* out)
+{
+    sim_->get_double_from_d_register(regnum, out);
+}
+
+bool
+ArmDebugger::getValue(const char* desc, int32_t* value)
+{
+    Register reg = Register::FromName(desc);
+    if (reg != InvalidReg) {
+        *value = getRegisterValue(reg.code());
+        return true;
+    }
+    if (strncmp(desc, "0x", 2) == 0)
+        return sscanf(desc + 2, "%x", reinterpret_cast<uint32_t*>(value)) == 1;
+    return sscanf(desc, "%u", reinterpret_cast<uint32_t*>(value)) == 1;
+}
+
+bool
+ArmDebugger::getVFPDoubleValue(const char* desc, double* value)
+{
+    FloatRegister reg(FloatRegister::FromName(desc));
+    if (reg != InvalidFloatReg) {
+        sim_->get_double_from_d_register(reg.code(), value);
+        return true;
+    }
+    return false;
+}
+
+bool
+ArmDebugger::setBreakpoint(SimInstruction* breakpc)
+{
+    // Check if a breakpoint can be set. If not return without any side-effects.
+    if (sim_->break_pc_)
+        return false;
+
+    // Set the breakpoint.
+    sim_->break_pc_ = breakpc;
+    sim_->break_instr_ = breakpc->instructionBits();
+    // Not setting the breakpoint instruction in the code itself. It will be set
+    // when the debugger shell continues.
+    return true;
+}
+
+bool
+ArmDebugger::deleteBreakpoint(SimInstruction* breakpc)
+{
+    if (sim_->break_pc_ != nullptr)
+        sim_->break_pc_->setInstructionBits(sim_->break_instr_);
+
+    sim_->break_pc_ = nullptr;
+    sim_->break_instr_ = 0;
+    return true;
+}
+
+void
+ArmDebugger::undoBreakpoints()
+{
+    if (sim_->break_pc_)
+        sim_->break_pc_->setInstructionBits(sim_->break_instr_);
+}
+
+void
+ArmDebugger::redoBreakpoints()
+{
+    if (sim_->break_pc_)
+        sim_->break_pc_->setInstructionBits(kBreakpointInstr);
+}
+
+static char*
+ReadLine(const char* prompt)
+{
+    char* result = nullptr;
+    char line_buf[256];
+    int offset = 0;
+    bool keep_going = true;
+    fprintf(stdout, "%s", prompt);
+    fflush(stdout);
+    while (keep_going) {
+        if (fgets(line_buf, sizeof(line_buf), stdin) == nullptr) {
+            // fgets got an error. Just give up.
+            if (result)
+                js_delete(result);
+            return nullptr;
+        }
+        int len = strlen(line_buf);
+        if (len > 0 && line_buf[len - 1] == '\n') {
+            // Since we read a new line we are done reading the line. This will
+            // exit the loop after copying this buffer into the result.
+            keep_going = false;
+        }
+        if (!result) {
+            // Allocate the initial result and make room for the terminating
+            // '\0'.
+            result = (char*)js_malloc(len + 1);
+            if (!result)
+                return nullptr;
+        } else {
+            // Allocate a new result with enough room for the new addition.
+            int new_len = offset + len + 1;
+            char* new_result = (char*)js_malloc(new_len);
+            if (!new_result)
+                return nullptr;
+            // Copy the existing input into the new array and set the new
+            // array as the result.
+            memcpy(new_result, result, offset * sizeof(char));
+            js_free(result);
+            result = new_result;
+        }
+        // Copy the newly read line into the result.
+        memcpy(result + offset, line_buf, len * sizeof(char));
+        offset += len;
+    }
+
+    MOZ_ASSERT(result);
+    result[offset] = '\0';
+    return result;
+}
+
+
+void
+ArmDebugger::debug()
+{
+    intptr_t last_pc = -1;
+    bool done = false;
+
+#define COMMAND_SIZE 63
+#define ARG_SIZE 255
+
+#define STR(a) #a
+#define XSTR(a) STR(a)
+
+    char cmd[COMMAND_SIZE + 1];
+    char arg1[ARG_SIZE + 1];
+    char arg2[ARG_SIZE + 1];
+    char* argv[3] = { cmd, arg1, arg2 };
+
+    // Make sure to have a proper terminating character if reaching the limit.
+    cmd[COMMAND_SIZE] = 0;
+    arg1[ARG_SIZE] = 0;
+    arg2[ARG_SIZE] = 0;
+
+    // Undo all set breakpoints while running in the debugger shell. This will
+    // make them invisible to all commands.
+    undoBreakpoints();
+
+#ifndef JS_DISASM_ARM
+    static bool disasm_warning_printed = false;
+    if (!disasm_warning_printed) {
+        printf("  No ARM disassembler present.  Enable JS_DISASM_ARM in configure.in.");
+        disasm_warning_printed = true;
+    }
+#endif
+
+    while (!done && !sim_->has_bad_pc()) {
+        if (last_pc != sim_->get_pc()) {
+#ifdef JS_DISASM_ARM
+            disasm::NameConverter converter;
+            disasm::Disassembler dasm(converter);
+            disasm::EmbeddedVector<char, disasm::ReasonableBufferSize> buffer;
+            dasm.InstructionDecode(buffer,
+                                   reinterpret_cast<uint8_t*>(sim_->get_pc()));
+            printf("  0x%08x  %s\n", sim_->get_pc(), buffer.start());
+#endif
+            last_pc = sim_->get_pc();
+        }
+        char* line = ReadLine("sim> ");
+        if (line == nullptr) {
+            break;
+        } else {
+            char* last_input = sim_->lastDebuggerInput();
+            if (strcmp(line, "\n") == 0 && last_input != nullptr) {
+                line = last_input;
+            } else {
+                // Ownership is transferred to sim_;
+                sim_->setLastDebuggerInput(line);
+            }
+
+            // Use sscanf to parse the individual parts of the command line. At the
+            // moment no command expects more than two parameters.
+            int argc = sscanf(line,
+                              "%" XSTR(COMMAND_SIZE) "s "
+                              "%" XSTR(ARG_SIZE) "s "
+                              "%" XSTR(ARG_SIZE) "s",
+                              cmd, arg1, arg2);
+            if (argc < 0) {
+                continue;
+            } else if ((strcmp(cmd, "si") == 0) || (strcmp(cmd, "stepi") == 0)) {
+                sim_->instructionDecode(reinterpret_cast<SimInstruction*>(sim_->get_pc()));
+                sim_->icount_++;
+            } else if ((strcmp(cmd, "skip") == 0)) {
+                sim_->set_pc(sim_->get_pc() + 4);
+                sim_->icount_++;
+            } else if ((strcmp(cmd, "c") == 0) || (strcmp(cmd, "cont") == 0)) {
+                // Execute the one instruction we broke at with breakpoints
+                // disabled.
+                sim_->instructionDecode(reinterpret_cast<SimInstruction*>(sim_->get_pc()));
+                sim_->icount_++;
+                // Leave the debugger shell.
+                done = true;
+            } else if ((strcmp(cmd, "p") == 0) || (strcmp(cmd, "print") == 0)) {
+                if (argc == 2 || (argc == 3 && strcmp(arg2, "fp") == 0)) {
+                    int32_t value;
+                    double dvalue;
+                    if (strcmp(arg1, "all") == 0) {
+                        for (uint32_t i = 0; i < Registers::Total; i++) {
+                            value = getRegisterValue(i);
+                            printf("%3s: 0x%08x %10d", Registers::GetName(i), value, value);
+                            if ((argc == 3 && strcmp(arg2, "fp") == 0) &&
+                                i < 8 &&
+                                (i % 2) == 0) {
+                                dvalue = getRegisterPairDoubleValue(i);
+                                printf(" (%.16g)\n", dvalue);
+                            } else {
+                                printf("\n");
+                            }
+                        }
+                        for (uint32_t i = 0; i < FloatRegisters::TotalPhys; i++) {
+                            getVFPDoubleRegisterValue(i, &dvalue);
+                            uint64_t as_words = mozilla::BitwiseCast<uint64_t>(dvalue);
+                            printf("%3s: %.16g 0x%08x %08x\n",
+                                   FloatRegister::FromCode(i).name(),
+                                   dvalue,
+                                   static_cast<uint32_t>(as_words >> 32),
+                                   static_cast<uint32_t>(as_words & 0xffffffff));
+                        }
+                    } else {
+                        if (getValue(arg1, &value)) {
+                            printf("%s: 0x%08x %d \n", arg1, value, value);
+                        } else if (getVFPDoubleValue(arg1, &dvalue)) {
+                            uint64_t as_words = mozilla::BitwiseCast<uint64_t>(dvalue);
+                            printf("%s: %.16g 0x%08x %08x\n",
+                                   arg1,
+                                   dvalue,
+                                   static_cast<uint32_t>(as_words >> 32),
+                                   static_cast<uint32_t>(as_words & 0xffffffff));
+                        } else {
+                            printf("%s unrecognized\n", arg1);
+                        }
+                    }
+                } else {
+                    printf("print <register>\n");
+                }
+            } else if (strcmp(cmd, "stack") == 0 || strcmp(cmd, "mem") == 0) {
+                int32_t* cur = nullptr;
+                int32_t* end = nullptr;
+                int next_arg = 1;
+
+                if (strcmp(cmd, "stack") == 0) {
+                    cur = reinterpret_cast<int32_t*>(sim_->get_register(Simulator::sp));
+                } else {  // "mem"
+                    int32_t value;
+                    if (!getValue(arg1, &value)) {
+                        printf("%s unrecognized\n", arg1);
+                        continue;
+                    }
+                    cur = reinterpret_cast<int32_t*>(value);
+                    next_arg++;
+                }
+
+                int32_t words;
+                if (argc == next_arg) {
+                    words = 10;
+                } else {
+                    if (!getValue(argv[next_arg], &words)) {
+                        words = 10;
+                    }
+                }
+                end = cur + words;
+
+                while (cur < end) {
+                    printf("  %p:  0x%08x %10d", cur, *cur, *cur);
+                    printf("\n");
+                    cur++;
+                }
+            } else if (strcmp(cmd, "disasm") == 0 || strcmp(cmd, "di") == 0) {
+#ifdef JS_DISASM_ARM
+                uint8_t* prev = nullptr;
+                uint8_t* cur = nullptr;
+                uint8_t* end = nullptr;
+
+                if (argc == 1) {
+                    cur = reinterpret_cast<uint8_t*>(sim_->get_pc());
+                    end = cur + (10 * SimInstruction::kInstrSize);
+                } else if (argc == 2) {
+                    Register reg = Register::FromName(arg1);
+                    if (reg != InvalidReg || strncmp(arg1, "0x", 2) == 0) {
+                        // The argument is an address or a register name.
+                        int32_t value;
+                        if (getValue(arg1, &value)) {
+                            cur = reinterpret_cast<uint8_t*>(value);
+                            // Disassemble 10 instructions at <arg1>.
+                            end = cur + (10 * SimInstruction::kInstrSize);
+                        }
+                    } else {
+                        // The argument is the number of instructions.
+                        int32_t value;
+                        if (getValue(arg1, &value)) {
+                            cur = reinterpret_cast<uint8_t*>(sim_->get_pc());
+                            // Disassemble <arg1> instructions.
+                            end = cur + (value * SimInstruction::kInstrSize);
+                        }
+                    }
+                } else {
+                    int32_t value1;
+                    int32_t value2;
+                    if (getValue(arg1, &value1) && getValue(arg2, &value2)) {
+                        cur = reinterpret_cast<uint8_t*>(value1);
+                        end = cur + (value2 * SimInstruction::kInstrSize);
+                    }
+                }
+                while (cur < end) {
+                    disasm::NameConverter converter;
+                    disasm::Disassembler dasm(converter);
+                    disasm::EmbeddedVector<char, disasm::ReasonableBufferSize> buffer;
+
+                    prev = cur;
+                    cur += dasm.InstructionDecode(buffer, cur);
+                    printf("  0x%08x  %s\n", reinterpret_cast<uint32_t>(prev), buffer.start());
+                }
+#endif
+            } else if (strcmp(cmd, "gdb") == 0) {
+                printf("relinquishing control to gdb\n");
+                asm("int $3");
+                printf("regaining control from gdb\n");
+            } else if (strcmp(cmd, "break") == 0) {
+                if (argc == 2) {
+                    int32_t value;
+                    if (getValue(arg1, &value)) {
+                        if (!setBreakpoint(reinterpret_cast<SimInstruction*>(value)))
+                            printf("setting breakpoint failed\n");
+                    } else {
+                        printf("%s unrecognized\n", arg1);
+                    }
+                } else {
+                    printf("break <address>\n");
+                }
+            } else if (strcmp(cmd, "del") == 0) {
+                if (!deleteBreakpoint(nullptr)) {
+                    printf("deleting breakpoint failed\n");
+                }
+            } else if (strcmp(cmd, "flags") == 0) {
+                printf("N flag: %d; ", sim_->n_flag_);
+                printf("Z flag: %d; ", sim_->z_flag_);
+                printf("C flag: %d; ", sim_->c_flag_);
+                printf("V flag: %d\n", sim_->v_flag_);
+                printf("INVALID OP flag: %d; ", sim_->inv_op_vfp_flag_);
+                printf("DIV BY ZERO flag: %d; ", sim_->div_zero_vfp_flag_);
+                printf("OVERFLOW flag: %d; ", sim_->overflow_vfp_flag_);
+                printf("UNDERFLOW flag: %d; ", sim_->underflow_vfp_flag_);
+                printf("INEXACT flag: %d;\n", sim_->inexact_vfp_flag_);
+            } else if (strcmp(cmd, "stop") == 0) {
+                int32_t value;
+                intptr_t stop_pc = sim_->get_pc() - 2 * SimInstruction::kInstrSize;
+                SimInstruction* stop_instr = reinterpret_cast<SimInstruction*>(stop_pc);
+                SimInstruction* msg_address =
+                    reinterpret_cast<SimInstruction*>(stop_pc + SimInstruction::kInstrSize);
+                if ((argc == 2) && (strcmp(arg1, "unstop") == 0)) {
+                    // Remove the current stop.
+                    if (sim_->isStopInstruction(stop_instr)) {
+                        stop_instr->setInstructionBits(kNopInstr);
+                        msg_address->setInstructionBits(kNopInstr);
+                    } else {
+                        printf("Not at debugger stop.\n");
+                    }
+                } else if (argc == 3) {
+                    // Print information about all/the specified breakpoint(s).
+                    if (strcmp(arg1, "info") == 0) {
+                        if (strcmp(arg2, "all") == 0) {
+                            printf("Stop information:\n");
+                            for (uint32_t i = 0; i < sim_->kNumOfWatchedStops; i++)
+                                sim_->printStopInfo(i);
+                        } else if (getValue(arg2, &value)) {
+                            sim_->printStopInfo(value);
+                        } else {
+                            printf("Unrecognized argument.\n");
+                        }
+                    } else if (strcmp(arg1, "enable") == 0) {
+                        // Enable all/the specified breakpoint(s).
+                        if (strcmp(arg2, "all") == 0) {
+                            for (uint32_t i = 0; i < sim_->kNumOfWatchedStops; i++)
+                                sim_->enableStop(i);
+                        } else if (getValue(arg2, &value)) {
+                            sim_->enableStop(value);
+                        } else {
+                            printf("Unrecognized argument.\n");
+                        }
+                    } else if (strcmp(arg1, "disable") == 0) {
+                        // Disable all/the specified breakpoint(s).
+                        if (strcmp(arg2, "all") == 0) {
+                            for (uint32_t i = 0; i < sim_->kNumOfWatchedStops; i++) {
+                                sim_->disableStop(i);
+                            }
+                        } else if (getValue(arg2, &value)) {
+                            sim_->disableStop(value);
+                        } else {
+                            printf("Unrecognized argument.\n");
+                        }
+                    }
+                } else {
+                    printf("Wrong usage. Use help command for more information.\n");
+                }
+            } else if ((strcmp(cmd, "h") == 0) || (strcmp(cmd, "help") == 0)) {
+                printf("cont\n");
+                printf("  continue execution (alias 'c')\n");
+                printf("skip\n");
+                printf("  skip one instruction (set pc to next instruction)\n");
+                printf("stepi\n");
+                printf("  step one instruction (alias 'si')\n");
+                printf("print <register>\n");
+                printf("  print register content (alias 'p')\n");
+                printf("  use register name 'all' to print all registers\n");
+                printf("  add argument 'fp' to print register pair double values\n");
+                printf("flags\n");
+                printf("  print flags\n");
+                printf("stack [<words>]\n");
+                printf("  dump stack content, default dump 10 words)\n");
+                printf("mem <address> [<words>]\n");
+                printf("  dump memory content, default dump 10 words)\n");
+                printf("disasm [<instructions>]\n");
+                printf("disasm [<address/register>]\n");
+                printf("disasm [[<address/register>] <instructions>]\n");
+                printf("  disassemble code, default is 10 instructions\n");
+                printf("  from pc (alias 'di')\n");
+                printf("gdb\n");
+                printf("  enter gdb\n");
+                printf("break <address>\n");
+                printf("  set a break point on the address\n");
+                printf("del\n");
+                printf("  delete the breakpoint\n");
+                printf("stop feature:\n");
+                printf("  Description:\n");
+                printf("    Stops are debug instructions inserted by\n");
+                printf("    the Assembler::stop() function.\n");
+                printf("    When hitting a stop, the Simulator will\n");
+                printf("    stop and and give control to the ArmDebugger.\n");
+                printf("    The first %d stop codes are watched:\n",
+                       Simulator::kNumOfWatchedStops);
+                printf("    - They can be enabled / disabled: the Simulator\n");
+                printf("      will / won't stop when hitting them.\n");
+                printf("    - The Simulator keeps track of how many times they \n");
+                printf("      are met. (See the info command.) Going over a\n");
+                printf("      disabled stop still increases its counter. \n");
+                printf("  Commands:\n");
+                printf("    stop info all/<code> : print infos about number <code>\n");
+                printf("      or all stop(s).\n");
+                printf("    stop enable/disable all/<code> : enables / disables\n");
+                printf("      all or number <code> stop(s)\n");
+                printf("    stop unstop\n");
+                printf("      ignore the stop instruction at the current location\n");
+                printf("      from now on\n");
+            } else {
+                printf("Unknown command: %s\n", cmd);
+            }
+        }
+    }
+
+    // Add all the breakpoints back to stop execution and enter the debugger
+    // shell when hit.
+    redoBreakpoints();
+
+#undef COMMAND_SIZE
+#undef ARG_SIZE
+
+#undef STR
+#undef XSTR
+}
+
+static bool
+AllOnOnePage(uintptr_t start, int size)
+{
+    intptr_t start_page = (start & ~CachePage::kPageMask);
+    intptr_t end_page = ((start + size) & ~CachePage::kPageMask);
+    return start_page == end_page;
+}
+
+static CachePage*
+GetCachePageLocked(Simulator::ICacheMap& i_cache, void* page)
+{
+    MOZ_ASSERT(Simulator::ICacheCheckingEnabled);
+
+    Simulator::ICacheMap::AddPtr p = i_cache.lookupForAdd(page);
+    if (p)
+        return p->value();
+
+    AutoEnterOOMUnsafeRegion oomUnsafe;
+    CachePage* new_page = js_new<CachePage>();
+    if (!new_page || !i_cache.add(p, page, new_page))
+        oomUnsafe.crash("Simulator CachePage");
+
+    return new_page;
+}
+
+// Flush from start up to and not including start + size.
+static void
+FlushOnePageLocked(Simulator::ICacheMap& i_cache, intptr_t start, int size)
+{
+    MOZ_ASSERT(size <= CachePage::kPageSize);
+    MOZ_ASSERT(AllOnOnePage(start, size - 1));
+    MOZ_ASSERT((start & CachePage::kLineMask) == 0);
+    MOZ_ASSERT((size & CachePage::kLineMask) == 0);
+
+    void* page = reinterpret_cast<void*>(start & (~CachePage::kPageMask));
+    int offset = (start & CachePage::kPageMask);
+    CachePage* cache_page = GetCachePageLocked(i_cache, page);
+    char* valid_bytemap = cache_page->validityByte(offset);
+    memset(valid_bytemap, CachePage::LINE_INVALID, size >> CachePage::kLineShift);
+}
+
+static void
+FlushICacheLocked(Simulator::ICacheMap& i_cache, void* start_addr, size_t size)
+{
+    intptr_t start = reinterpret_cast<intptr_t>(start_addr);
+    int intra_line = (start & CachePage::kLineMask);
+    start -= intra_line;
+    size += intra_line;
+    size = ((size - 1) | CachePage::kLineMask) + 1;
+    int offset = (start & CachePage::kPageMask);
+    while (!AllOnOnePage(start, size - 1)) {
+        int bytes_to_flush = CachePage::kPageSize - offset;
+        FlushOnePageLocked(i_cache, start, bytes_to_flush);
+        start += bytes_to_flush;
+        size -= bytes_to_flush;
+        MOZ_ASSERT((start & CachePage::kPageMask) == 0);
+        offset = 0;
+    }
+    if (size != 0)
+        FlushOnePageLocked(i_cache, start, size);
+}
+
+static void
+CheckICacheLocked(Simulator::ICacheMap& i_cache, SimInstruction* instr)
+{
+    intptr_t address = reinterpret_cast<intptr_t>(instr);
+    void* page = reinterpret_cast<void*>(address & (~CachePage::kPageMask));
+    void* line = reinterpret_cast<void*>(address & (~CachePage::kLineMask));
+    int offset = (address & CachePage::kPageMask);
+    CachePage* cache_page = GetCachePageLocked(i_cache, page);
+    char* cache_valid_byte = cache_page->validityByte(offset);
+    bool cache_hit = (*cache_valid_byte == CachePage::LINE_VALID);
+    char* cached_line = cache_page->cachedData(offset & ~CachePage::kLineMask);
+    if (cache_hit) {
+        // Check that the data in memory matches the contents of the I-cache.
+        MOZ_ASSERT(memcmp(reinterpret_cast<void*>(instr),
+                          cache_page->cachedData(offset),
+                          SimInstruction::kInstrSize) == 0);
+    } else {
+        // Cache miss. Load memory into the cache.
+        memcpy(cached_line, line, CachePage::kLineLength);
+        *cache_valid_byte = CachePage::LINE_VALID;
+    }
+}
+
+HashNumber
+Simulator::ICacheHasher::hash(const Lookup& l)
+{
+    return static_cast<uint32_t>(reinterpret_cast<uintptr_t>(l)) >> 2;
+}
+
+bool
+Simulator::ICacheHasher::match(const Key& k, const Lookup& l)
+{
+    MOZ_ASSERT((reinterpret_cast<intptr_t>(k) & CachePage::kPageMask) == 0);
+    MOZ_ASSERT((reinterpret_cast<intptr_t>(l) & CachePage::kPageMask) == 0);
+    return k == l;
+}
+
+void
+Simulator::setLastDebuggerInput(char* input)
+{
+    js_free(lastDebuggerInput_);
+    lastDebuggerInput_ = input;
+}
+
+void
+Simulator::FlushICache(void* start_addr, size_t size)
+{
+    JitSpewCont(JitSpew_CacheFlush, "[%p %" PRIxSIZE "]", start_addr, size);
+    if (Simulator::ICacheCheckingEnabled) {
+        Simulator* sim = Simulator::Current();
+
+        AutoLockSimulatorCache als(sim);
+
+        js::jit::FlushICacheLocked(sim->icache(), start_addr, size);
+    }
+}
+
+Simulator::Simulator(JSContext* cx)
+  : cx_(cx),
+    cacheLock_(mutexid::SimulatorCacheLock)
+{
+    // Set up simulator support first. Some of this information is needed to
+    // setup the architecture state.
+
+    // Note, allocation and anything that depends on allocated memory is
+    // deferred until init(), in order to handle OOM properly.
+
+    stack_ = nullptr;
+    stackLimit_ = 0;
+    pc_modified_ = false;
+    icount_ = 0L;
+    resume_pc_ = 0;
+    break_pc_ = nullptr;
+    break_instr_ = 0;
+    single_stepping_ = false;
+    single_step_callback_ = nullptr;
+    single_step_callback_arg_ = nullptr;
+    skipCalleeSavedRegsCheck = false;
+
+    // Set up architecture state.
+    // All registers are initialized to zero to start with.
+    for (int i = 0; i < num_registers; i++)
+        registers_[i] = 0;
+
+    n_flag_ = false;
+    z_flag_ = false;
+    c_flag_ = false;
+    v_flag_ = false;
+
+    for (int i = 0; i < num_d_registers * 2; i++)
+        vfp_registers_[i] = 0;
+
+    n_flag_FPSCR_ = false;
+    z_flag_FPSCR_ = false;
+    c_flag_FPSCR_ = false;
+    v_flag_FPSCR_ = false;
+    FPSCR_rounding_mode_ = SimRZ;
+    FPSCR_default_NaN_mode_ = true;
+
+    inv_op_vfp_flag_ = false;
+    div_zero_vfp_flag_ = false;
+    overflow_vfp_flag_ = false;
+    underflow_vfp_flag_ = false;
+    inexact_vfp_flag_ = false;
+
+    // The lr and pc are initialized to a known bad value that will cause an
+    // access violation if the simulator ever tries to execute it.
+    registers_[pc] = bad_lr;
+    registers_[lr] = bad_lr;
+
+    lastDebuggerInput_ = nullptr;
+
+    redirection_ = nullptr;
+    exclusiveMonitorHeld_ = false;
+    exclusiveMonitor_ = 0;
+}
+
+bool
+Simulator::init()
+{
+    if (!icache_.init())
+        return false;
+
+    // Allocate 2MB for the stack. Note that we will only use 1MB, see below.
+    static const size_t stackSize = 2 * 1024*1024;
+    stack_ = reinterpret_cast<char*>(js_malloc(stackSize));
+    if (!stack_)
+        return false;
+
+    // Leave a safety margin of 1MB to prevent overrunning the stack when
+    // pushing values (total stack size is 2MB).
+    stackLimit_ = reinterpret_cast<uintptr_t>(stack_) + 1024 * 1024;
+
+    // The sp is initialized to point to the bottom (high address) of the
+    // allocated stack area. To be safe in potential stack underflows we leave
+    // some buffer below.
+    registers_[sp] = reinterpret_cast<int32_t>(stack_) + stackSize - 64;
+
+    return true;
+}
+
+// When the generated code calls a VM function (masm.callWithABI) we need to
+// call that function instead of trying to execute it with the simulator
+// (because it's x86 code instead of arm code). We do that by redirecting the VM
+// call to a svc (Supervisor Call) instruction that is handled by the
+// simulator. We write the original destination of the jump just at a known
+// offset from the svc instruction so the simulator knows what to call.
+class Redirection
+{
+    friend class Simulator;
+
+    // sim's lock must already be held.
+    Redirection(void* nativeFunction, ABIFunctionType type, Simulator* sim)
+      : nativeFunction_(nativeFunction),
+        swiInstruction_(Assembler::AL | (0xf * (1 << 24)) | kCallRtRedirected),
+        type_(type),
+        next_(nullptr)
+    {
+        next_ = sim->redirection();
+        if (Simulator::ICacheCheckingEnabled)
+            FlushICacheLocked(sim->icache(), addressOfSwiInstruction(), SimInstruction::kInstrSize);
+        sim->setRedirection(this);
+    }
+
+  public:
+    void* addressOfSwiInstruction() { return &swiInstruction_; }
+    void* nativeFunction() const { return nativeFunction_; }
+    ABIFunctionType type() const { return type_; }
+
+    static Redirection* Get(void* nativeFunction, ABIFunctionType type) {
+        Simulator* sim = Simulator::Current();
+
+        AutoLockSimulatorCache als(sim);
+
+        Redirection* current = sim->redirection();
+        for (; current != nullptr; current = current->next_) {
+            if (current->nativeFunction_ == nativeFunction) {
+                MOZ_ASSERT(current->type() == type);
+                return current;
+            }
+        }
+
+        AutoEnterOOMUnsafeRegion oomUnsafe;
+        Redirection* redir = (Redirection*)js_malloc(sizeof(Redirection));
+        if (!redir)
+            oomUnsafe.crash("Simulator redirection");
+        new(redir) Redirection(nativeFunction, type, sim);
+        return redir;
+    }
+
+    static Redirection* FromSwiInstruction(SimInstruction* swiInstruction) {
+        uint8_t* addrOfSwi = reinterpret_cast<uint8_t*>(swiInstruction);
+        uint8_t* addrOfRedirection = addrOfSwi - offsetof(Redirection, swiInstruction_);
+        return reinterpret_cast<Redirection*>(addrOfRedirection);
+    }
+
+  private:
+    void* nativeFunction_;
+    uint32_t swiInstruction_;
+    ABIFunctionType type_;
+    Redirection* next_;
+};
+
+Simulator::~Simulator()
+{
+    js_free(stack_);
+    Redirection* r = redirection_;
+    while (r) {
+        Redirection* next = r->next_;
+        js_delete(r);
+        r = next;
+    }
+}
+
+/* static */ void*
+Simulator::RedirectNativeFunction(void* nativeFunction, ABIFunctionType type)
+{
+    Redirection* redirection = Redirection::Get(nativeFunction, type);
+    return redirection->addressOfSwiInstruction();
+}
+
+// Sets the register in the architecture state. It will also deal with updating
+// Simulator internal state for special registers such as PC.
+void
+Simulator::set_register(int reg, int32_t value)
+{
+    MOZ_ASSERT(reg >= 0 && reg < num_registers);
+    if (reg == pc)
+        pc_modified_ = true;
+    registers_[reg] = value;
+}
+
+// Get the register from the architecture state. This function does handle the
+// special case of accessing the PC register.
+int32_t
+Simulator::get_register(int reg) const
+{
+    MOZ_ASSERT(reg >= 0 && reg < num_registers);
+    // Work around GCC bug: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43949
+    if (reg >= num_registers) return 0;
+    return registers_[reg] + ((reg == pc) ? SimInstruction::kPCReadOffset : 0);
+}
+
+double
+Simulator::get_double_from_register_pair(int reg)
+{
+    MOZ_ASSERT(reg >= 0 && reg < num_registers && (reg % 2) == 0);
+
+    // Read the bits from the unsigned integer register_[] array into the double
+    // precision floating point value and return it.
+    double dm_val = 0.0;
+    char buffer[2 * sizeof(vfp_registers_[0])];
+    memcpy(buffer, &registers_[reg], 2 * sizeof(registers_[0]));
+    memcpy(&dm_val, buffer, 2 * sizeof(registers_[0]));
+    return dm_val;
+}
+
+void
+Simulator::set_register_pair_from_double(int reg, double* value)
+{
+    MOZ_ASSERT(reg >= 0 && reg < num_registers && (reg % 2) == 0);
+    memcpy(registers_ + reg, value, sizeof(*value));
+}
+
+void
+Simulator::set_dw_register(int dreg, const int* dbl)
+{
+    MOZ_ASSERT(dreg >= 0 && dreg < num_d_registers);
+    registers_[dreg] = dbl[0];
+    registers_[dreg + 1] = dbl[1];
+}
+
+void
+Simulator::get_d_register(int dreg, uint64_t* value)
+{
+    MOZ_ASSERT(dreg >= 0 && dreg < int(FloatRegisters::TotalPhys));
+    memcpy(value, vfp_registers_ + dreg * 2, sizeof(*value));
+}
+
+void
+Simulator::set_d_register(int dreg, const uint64_t* value)
+{
+    MOZ_ASSERT(dreg >= 0 && dreg < int(FloatRegisters::TotalPhys));
+    memcpy(vfp_registers_ + dreg * 2, value, sizeof(*value));
+}
+
+void
+Simulator::get_d_register(int dreg, uint32_t* value)
+{
+    MOZ_ASSERT(dreg >= 0 && dreg < int(FloatRegisters::TotalPhys));
+    memcpy(value, vfp_registers_ + dreg * 2, sizeof(*value) * 2);
+}
+
+void
+Simulator::set_d_register(int dreg, const uint32_t* value)
+{
+    MOZ_ASSERT(dreg >= 0 && dreg < int(FloatRegisters::TotalPhys));
+    memcpy(vfp_registers_ + dreg * 2, value, sizeof(*value) * 2);
+}
+
+void
+Simulator::get_q_register(int qreg, uint64_t* value)
+{
+    MOZ_ASSERT(qreg >= 0 && qreg < num_q_registers);
+    memcpy(value, vfp_registers_ + qreg * 4, sizeof(*value) * 2);
+}
+
+void
+Simulator::set_q_register(int qreg, const uint64_t* value)
+{
+    MOZ_ASSERT(qreg >= 0 && qreg < num_q_registers);
+    memcpy(vfp_registers_ + qreg * 4, value, sizeof(*value) * 2);
+}
+
+void
+Simulator::get_q_register(int qreg, uint32_t* value)
+{
+    MOZ_ASSERT(qreg >= 0 && qreg < num_q_registers);
+    memcpy(value, vfp_registers_ + qreg * 4, sizeof(*value) * 4);
+}
+
+void
+Simulator::set_q_register(int qreg, const uint32_t* value)
+{
+    MOZ_ASSERT((qreg >= 0) && (qreg < num_q_registers));
+    memcpy(vfp_registers_ + qreg * 4, value, sizeof(*value) * 4);
+}
+
+void
+Simulator::set_pc(int32_t value)
+{
+    pc_modified_ = true;
+    registers_[pc] = value;
+}
+
+bool
+Simulator::has_bad_pc() const
+{
+    return registers_[pc] == bad_lr || registers_[pc] == end_sim_pc;
+}
+
+// Raw access to the PC register without the special adjustment when reading.
+int32_t
+Simulator::get_pc() const
+{
+    return registers_[pc];
+}
+
+void
+Simulator::set_s_register(int sreg, unsigned int value)
+{
+    MOZ_ASSERT(sreg >= 0 && sreg < num_s_registers);
+    vfp_registers_[sreg] = value;
+}
+
+unsigned
+Simulator::get_s_register(int sreg) const
+{
+    MOZ_ASSERT(sreg >= 0 && sreg < num_s_registers);
+    return vfp_registers_[sreg];
+}
+
+template<class InputType, int register_size>
+void
+Simulator::setVFPRegister(int reg_index, const InputType& value)
+{
+    MOZ_ASSERT(reg_index >= 0);
+    MOZ_ASSERT_IF(register_size == 1, reg_index < num_s_registers);
+    MOZ_ASSERT_IF(register_size == 2, reg_index < int(FloatRegisters::TotalPhys));
+
+    char buffer[register_size * sizeof(vfp_registers_[0])];
+    memcpy(buffer, &value, register_size * sizeof(vfp_registers_[0]));
+    memcpy(&vfp_registers_[reg_index * register_size], buffer,
+           register_size * sizeof(vfp_registers_[0]));
+}
+
+template<class ReturnType, int register_size>
+void Simulator::getFromVFPRegister(int reg_index, ReturnType* out)
+{
+    MOZ_ASSERT(reg_index >= 0);
+    MOZ_ASSERT_IF(register_size == 1, reg_index < num_s_registers);
+    MOZ_ASSERT_IF(register_size == 2, reg_index < int(FloatRegisters::TotalPhys));
+
+    char buffer[register_size * sizeof(vfp_registers_[0])];
+    memcpy(buffer, &vfp_registers_[register_size * reg_index],
+           register_size * sizeof(vfp_registers_[0]));
+    memcpy(out, buffer, register_size * sizeof(vfp_registers_[0]));
+}
+
+// These forced-instantiations are for jsapi-tests. Evidently, nothing
+// requires these to be instantiated.
+template void Simulator::getFromVFPRegister<double, 2>(int reg_index, double* out);
+template void Simulator::getFromVFPRegister<float, 1>(int reg_index, float* out);
+template void Simulator::setVFPRegister<double, 2>(int reg_index, const double& value);
+template void Simulator::setVFPRegister<float, 1>(int reg_index, const float& value);
+
+void
+Simulator::getFpArgs(double* x, double* y, int32_t* z)
+{
+    if (UseHardFpABI()) {
+        get_double_from_d_register(0, x);
+        get_double_from_d_register(1, y);
+        *z = get_register(0);
+    } else {
+        *x = get_double_from_register_pair(0);
+        *y = get_double_from_register_pair(2);
+        *z = get_register(2);
+    }
+}
+
+void
+Simulator::getFpFromStack(int32_t* stack, double* x)
+{
+    MOZ_ASSERT(stack && x);
+    char buffer[2 * sizeof(stack[0])];
+    memcpy(buffer, stack, 2 * sizeof(stack[0]));
+    memcpy(x, buffer, 2 * sizeof(stack[0]));
+}
+
+void
+Simulator::setCallResultDouble(double result)
+{
+    // The return value is either in r0/r1 or d0.
+    if (UseHardFpABI()) {
+        char buffer[2 * sizeof(vfp_registers_[0])];
+        memcpy(buffer, &result, sizeof(buffer));
+        // Copy result to d0.
+        memcpy(vfp_registers_, buffer, sizeof(buffer));
+    } else {
+        char buffer[2 * sizeof(registers_[0])];
+        memcpy(buffer, &result, sizeof(buffer));
+        // Copy result to r0 and r1.
+        memcpy(registers_, buffer, sizeof(buffer));
+    }
+}
+
+void
+Simulator::setCallResultFloat(float result)
+{
+    if (UseHardFpABI()) {
+        char buffer[sizeof(registers_[0])];
+        memcpy(buffer, &result, sizeof(buffer));
+        // Copy result to s0.
+        memcpy(vfp_registers_, buffer, sizeof(buffer));
+    } else {
+        char buffer[sizeof(registers_[0])];
+        memcpy(buffer, &result, sizeof(buffer));
+        // Copy result to r0.
+        memcpy(registers_, buffer, sizeof(buffer));
+    }
+}
+
+void
+Simulator::setCallResult(int64_t res)
+{
+    set_register(r0, static_cast<int32_t>(res));
+    set_register(r1, static_cast<int32_t>(res >> 32));
+}
+
+void
+Simulator::exclusiveMonitorSet(uint64_t value)
+{
+    exclusiveMonitor_ = value;
+    exclusiveMonitorHeld_ = true;
+}
+
+uint64_t
+Simulator::exclusiveMonitorGetAndClear(bool* held)
+{
+    *held = exclusiveMonitorHeld_;
+    exclusiveMonitorHeld_ = false;
+    return *held ? exclusiveMonitor_ : 0;
+}
+
+void
+Simulator::exclusiveMonitorClear()
+{
+    exclusiveMonitorHeld_ = false;
+}
+
+// WebAssembly memories contain an extra region of guard pages (see
+// WasmArrayRawBuffer comment). The guard pages catch out-of-bounds accesses
+// using a signal handler that redirects PC to a stub that safely reports an
+// error. However, if the handler is hit by the simulator, the PC is in C++ code
+// and cannot be redirected. Therefore, we must avoid hitting the handler by
+// redirecting in the simulator before the real handler would have been hit.
+bool
+Simulator::handleWasmFault(int32_t addr, unsigned numBytes)
+{
+    WasmActivation* act = cx_->wasmActivationStack();
+    if (!act)
+        return false;
+
+    void* pc = reinterpret_cast<void*>(get_pc());
+    wasm::Instance* instance = act->compartment()->wasm.lookupInstanceDeprecated(pc);
+    if (!instance || !instance->memoryAccessInGuardRegion((uint8_t*)addr, numBytes))
+        return false;
+
+    const wasm::MemoryAccess* memoryAccess = instance->code().lookupMemoryAccess(pc);
+    if (!memoryAccess) {
+        set_pc(int32_t(instance->codeSegment().outOfBoundsCode()));
+        return true;
+    }
+
+    MOZ_ASSERT(memoryAccess->hasTrapOutOfLineCode());
+    set_pc(int32_t(memoryAccess->trapOutOfLineCode(instance->codeBase())));
+    return true;
+}
+
+uint64_t
+Simulator::readQ(int32_t addr, SimInstruction* instr, UnalignedPolicy f)
+{
+    if (handleWasmFault(addr, 8))
+        return -1;
+
+    if ((addr & 3) == 0 || (f == AllowUnaligned && !HasAlignmentFault())) {
+        uint64_t* ptr = reinterpret_cast<uint64_t*>(addr);
+        return *ptr;
+    }
+
+    // See the comments below in readW.
+    if (FixupFault() && wasm::IsPCInWasmCode(reinterpret_cast<void *>(get_pc()))) {
+        char* ptr = reinterpret_cast<char*>(addr);
+        uint64_t value;
+        memcpy(&value, ptr, sizeof(value));
+        return value;
+    }
+
+    printf("Unaligned read at 0x%08x, pc=%p\n", addr, instr);
+    MOZ_CRASH();
+}
+
+void
+Simulator::writeQ(int32_t addr, uint64_t value, SimInstruction* instr, UnalignedPolicy f)
+{
+    if (handleWasmFault(addr, 8))
+        return;
+
+    if ((addr & 3) == 0 || (f == AllowUnaligned && !HasAlignmentFault())) {
+        uint64_t* ptr = reinterpret_cast<uint64_t*>(addr);
+        *ptr = value;
+        return;
+    }
+
+    // See the comments below in readW.
+    if (FixupFault() && wasm::IsPCInWasmCode(reinterpret_cast<void *>(get_pc()))) {
+        char* ptr = reinterpret_cast<char*>(addr);
+        memcpy(ptr, &value, sizeof(value));
+        return;
+    }
+
+    printf("Unaligned write at 0x%08x, pc=%p\n", addr, instr);
+    MOZ_CRASH();
+}
+
+int
+Simulator::readW(int32_t addr, SimInstruction* instr, UnalignedPolicy f)
+{
+    if (handleWasmFault(addr, 4))
+        return -1;
+
+    if ((addr & 3) == 0 || (f == AllowUnaligned && !HasAlignmentFault())) {
+        intptr_t* ptr = reinterpret_cast<intptr_t*>(addr);
+        return *ptr;
+    }
+
+    // In WebAssembly, we want unaligned accesses to either raise a signal or
+    // do the right thing. Making this simulator properly emulate the behavior
+    // of raising a signal is complex, so as a special-case, when in wasm code,
+    // we just do the right thing.
+    if (FixupFault() && wasm::IsPCInWasmCode(reinterpret_cast<void *>(get_pc()))) {
+        char* ptr = reinterpret_cast<char*>(addr);
+        int value;
+        memcpy(&value, ptr, sizeof(value));
+        return value;
+    }
+
+    printf("Unaligned read at 0x%08x, pc=%p\n", addr, instr);
+    MOZ_CRASH();
+}
+
+void
+Simulator::writeW(int32_t addr, int value, SimInstruction* instr, UnalignedPolicy f)
+{
+    if (handleWasmFault(addr, 4))
+        return;
+
+    if ((addr & 3) == 0 || (f == AllowUnaligned && !HasAlignmentFault())) {
+        intptr_t* ptr = reinterpret_cast<intptr_t*>(addr);
+        *ptr = value;
+        return;
+    }
+
+    // See the comments above in readW.
+    if (FixupFault() && wasm::IsPCInWasmCode(reinterpret_cast<void *>(get_pc()))) {
+        char* ptr = reinterpret_cast<char*>(addr);
+        memcpy(ptr, &value, sizeof(value));
+        return;
+    }
+
+    printf("Unaligned write at 0x%08x, pc=%p\n", addr, instr);
+    MOZ_CRASH();
+}
+
+// For the time being, define Relaxed operations in terms of SeqCst
+// operations - we don't yet need Relaxed operations anywhere else in
+// the system, and the distinction is not important to the simulation
+// at the level where we're operating.
+
+template<typename T>
+static
+T loadRelaxed(SharedMem<T*> addr)
+{
+    return AtomicOperations::loadSeqCst(addr);
+}
+
+template<typename T>
+static
+T compareExchangeRelaxed(SharedMem<T*> addr, T oldval, T newval)
+{
+    return AtomicOperations::compareExchangeSeqCst(addr, oldval, newval);
+}
+
+int
+Simulator::readExW(int32_t addr, SimInstruction* instr)
+{
+    // The regexp engine emits unaligned loads, so we don't check for them here
+    // like most of the other methods do.
+    if ((addr & 3) == 0 || !HasAlignmentFault()) {
+        SharedMem<int32_t*> ptr = SharedMem<int32_t*>::shared(reinterpret_cast<int32_t*>(addr));
+        int32_t value = loadRelaxed(ptr);
+        exclusiveMonitorSet(value);
+        return value;
+    } else {
+        printf("Unaligned write at 0x%08x, pc=%p\n", addr, instr);
+        MOZ_CRASH();
+    }
+}
+
+int32_t
+Simulator::writeExW(int32_t addr, int value, SimInstruction* instr)
+{
+    if ((addr & 3) == 0) {
+        SharedMem<int32_t*> ptr = SharedMem<int32_t*>::shared(reinterpret_cast<int32_t*>(addr));
+        bool held;
+        int32_t expected = int32_t(exclusiveMonitorGetAndClear(&held));
+        if (!held)
+            return 1;
+        int32_t old = compareExchangeRelaxed(ptr, expected, int32_t(value));
+        return old != expected;
+    }
+
+    printf("Unaligned write at 0x%08x, pc=%p\n", addr, instr);
+    MOZ_CRASH();
+}
+
+uint16_t
+Simulator::readHU(int32_t addr, SimInstruction* instr)
+{
+    if (handleWasmFault(addr, 2))
+        return UINT16_MAX;
+
+    // The regexp engine emits unaligned loads, so we don't check for them here
+    // like most of the other methods do.
+    if ((addr & 1) == 0 || !HasAlignmentFault()) {
+        uint16_t* ptr = reinterpret_cast<uint16_t*>(addr);
+        return *ptr;
+    }
+
+    // See comments above in readW.
+    if (FixupFault() && wasm::IsPCInWasmCode(reinterpret_cast<void *>(get_pc()))) {
+        char* ptr = reinterpret_cast<char*>(addr);
+        uint16_t value;
+        memcpy(&value, ptr, sizeof(value));
+        return value;
+    }
+
+    printf("Unaligned unsigned halfword read at 0x%08x, pc=%p\n", addr, instr);
+    MOZ_CRASH();
+    return 0;
+}
+
+int16_t
+Simulator::readH(int32_t addr, SimInstruction* instr)
+{
+    if (handleWasmFault(addr, 2))
+        return -1;
+
+    if ((addr & 1) == 0 || !HasAlignmentFault()) {
+        int16_t* ptr = reinterpret_cast<int16_t*>(addr);
+        return *ptr;
+    }
+
+    // See comments above in readW.
+    if (FixupFault() && wasm::IsPCInWasmCode(reinterpret_cast<void *>(get_pc()))) {
+        char* ptr = reinterpret_cast<char*>(addr);
+        int16_t value;
+        memcpy(&value, ptr, sizeof(value));
+        return value;
+    }
+
+    printf("Unaligned signed halfword read at 0x%08x\n", addr);
+    MOZ_CRASH();
+    return 0;
+}
+
+void
+Simulator::writeH(int32_t addr, uint16_t value, SimInstruction* instr)
+{
+    if (handleWasmFault(addr, 2))
+        return;
+
+    if ((addr & 1) == 0 || !HasAlignmentFault()) {
+        uint16_t* ptr = reinterpret_cast<uint16_t*>(addr);
+        *ptr = value;
+        return;
+    }
+
+    // See the comments above in readW.
+    if (FixupFault() && wasm::IsPCInWasmCode(reinterpret_cast<void *>(get_pc()))) {
+        char* ptr = reinterpret_cast<char*>(addr);
+        memcpy(ptr, &value, sizeof(value));
+        return;
+    }
+
+    printf("Unaligned unsigned halfword write at 0x%08x, pc=%p\n", addr, instr);
+    MOZ_CRASH();
+}
+
+void
+Simulator::writeH(int32_t addr, int16_t value, SimInstruction* instr)
+{
+    if (handleWasmFault(addr, 2))
+        return;
+
+    if ((addr & 1) == 0 || !HasAlignmentFault()) {
+        int16_t* ptr = reinterpret_cast<int16_t*>(addr);
+        *ptr = value;
+        return;
+    }
+
+    // See the comments above in readW.
+    if (FixupFault() && wasm::IsPCInWasmCode(reinterpret_cast<void *>(get_pc()))) {
+        char* ptr = reinterpret_cast<char*>(addr);
+        memcpy(ptr, &value, sizeof(value));
+        return;
+    }
+
+    printf("Unaligned halfword write at 0x%08x, pc=%p\n", addr, instr);
+    MOZ_CRASH();
+}
+
+uint16_t
+Simulator::readExHU(int32_t addr, SimInstruction* instr)
+{
+    // The regexp engine emits unaligned loads, so we don't check for them here
+    // like most of the other methods do.
+    if ((addr & 1) == 0 || !HasAlignmentFault()) {
+        SharedMem<uint16_t*> ptr = SharedMem<uint16_t*>::shared(reinterpret_cast<uint16_t*>(addr));
+        uint16_t value = loadRelaxed(ptr);
+        exclusiveMonitorSet(value);
+        return value;
+    }
+    printf("Unaligned atomic unsigned halfword read at 0x%08x, pc=%p\n", addr, instr);
+    MOZ_CRASH();
+    return 0;
+}
+
+int32_t
+Simulator::writeExH(int32_t addr, uint16_t value, SimInstruction* instr)
+{
+    if ((addr & 1) == 0) {
+        SharedMem<uint16_t*> ptr = SharedMem<uint16_t*>::shared(reinterpret_cast<uint16_t*>(addr));
+        bool held;
+        uint16_t expected = uint16_t(exclusiveMonitorGetAndClear(&held));
+        if (!held)
+            return 1;
+        uint16_t old = compareExchangeRelaxed(ptr, expected, value);
+        return old != expected;
+    } else {
+        printf("Unaligned atomic unsigned halfword write at 0x%08x, pc=%p\n", addr, instr);
+        MOZ_CRASH();
+    }
+}
+
+uint8_t
+Simulator::readBU(int32_t addr)
+{
+    if (handleWasmFault(addr, 1))
+        return UINT8_MAX;
+
+    uint8_t* ptr = reinterpret_cast<uint8_t*>(addr);
+    return *ptr;
+}
+
+uint8_t
+Simulator::readExBU(int32_t addr)
+{
+    SharedMem<uint8_t*> ptr = SharedMem<uint8_t*>::shared(reinterpret_cast<uint8_t*>(addr));
+    uint8_t value = loadRelaxed(ptr);
+    exclusiveMonitorSet(value);
+    return value;
+}
+
+int32_t
+Simulator::writeExB(int32_t addr, uint8_t value)
+{
+    SharedMem<uint8_t*> ptr = SharedMem<uint8_t*>::shared(reinterpret_cast<uint8_t*>(addr));
+    bool held;
+    uint8_t expected = uint8_t(exclusiveMonitorGetAndClear(&held));
+    if (!held)
+        return 1;
+    uint8_t old = compareExchangeRelaxed(ptr, expected, value);
+    return old != expected;
+}
+
+int8_t
+Simulator::readB(int32_t addr)
+{
+    if (handleWasmFault(addr, 1))
+        return -1;
+
+    int8_t* ptr = reinterpret_cast<int8_t*>(addr);
+    return *ptr;
+}
+
+void
+Simulator::writeB(int32_t addr, uint8_t value)
+{
+    if (handleWasmFault(addr, 1))
+        return;
+
+    uint8_t* ptr = reinterpret_cast<uint8_t*>(addr);
+    *ptr = value;
+}
+
+void
+Simulator::writeB(int32_t addr, int8_t value)
+{
+    if (handleWasmFault(addr, 1))
+        return;
+
+    int8_t* ptr = reinterpret_cast<int8_t*>(addr);
+    *ptr = value;
+}
+
+int32_t*
+Simulator::readDW(int32_t addr)
+{
+    if ((addr & 3) == 0) {
+        int32_t* ptr = reinterpret_cast<int32_t*>(addr);
+        return ptr;
+    }
+    printf("Unaligned read at 0x%08x\n", addr);
+    MOZ_CRASH();
+    return 0;
+}
+
+void
+Simulator::writeDW(int32_t addr, int32_t value1, int32_t value2)
+{
+    if ((addr & 3) == 0) {
+        int32_t* ptr = reinterpret_cast<int32_t*>(addr);
+        *ptr++ = value1;
+        *ptr = value2;
+    } else {
+        printf("Unaligned write at 0x%08x\n", addr);
+        MOZ_CRASH();
+    }
+}
+
+int32_t
+Simulator::readExDW(int32_t addr, int32_t* hibits)
+{
+#if defined(__clang__) && defined(__i386)
+    // This is OK for now, we don't yet generate LDREXD.
+    MOZ_CRASH("Unimplemented - 8-byte atomics are unsupported in Clang on i386");
+#else
+    if ((addr & 3) == 0) {
+        SharedMem<uint64_t*> ptr = SharedMem<uint64_t*>::shared(reinterpret_cast<uint64_t*>(addr));
+        uint64_t value = loadRelaxed(ptr);
+        exclusiveMonitorSet(value);
+        *hibits = int32_t(value);
+        return int32_t(value >> 32);
+    }
+    printf("Unaligned read at 0x%08x\n", addr);
+    MOZ_CRASH();
+    return 0;
+#endif
+}
+
+int32_t
+Simulator::writeExDW(int32_t addr, int32_t value1, int32_t value2)
+{
+#if defined(__clang__) && defined(__i386)
+    // This is OK for now, we don't yet generate STREXD.
+    MOZ_CRASH("Unimplemented - 8-byte atomics are unsupported in Clang on i386");
+#else
+    if ((addr & 3) == 0) {
+        SharedMem<uint64_t*> ptr = SharedMem<uint64_t*>::shared(reinterpret_cast<uint64_t*>(addr));
+        uint64_t value = (uint64_t(value1) << 32) | uint32_t(value2);
+        bool held;
+        uint64_t expected = exclusiveMonitorGetAndClear(&held);
+        if (!held)
+            return 1;
+        uint64_t old = compareExchangeRelaxed(ptr, expected, value);
+        return old != expected;
+    } else {
+        printf("Unaligned write at 0x%08x\n", addr);
+        MOZ_CRASH();
+    }
+#endif
+}
+
+uintptr_t
+Simulator::stackLimit() const
+{
+    return stackLimit_;
+}
+
+uintptr_t*
+Simulator::addressOfStackLimit()
+{
+    return &stackLimit_;
+}
+
+bool
+Simulator::overRecursed(uintptr_t newsp) const
+{
+    if (newsp == 0)
+        newsp = get_register(sp);
+    return newsp <= stackLimit();
+}
+
+bool
+Simulator::overRecursedWithExtra(uint32_t extra) const
+{
+    uintptr_t newsp = get_register(sp) - extra;
+    return newsp <= stackLimit();
+}
+
+// Checks if the current instruction should be executed based on its condition
+// bits.
+bool
+Simulator::conditionallyExecute(SimInstruction* instr)
+{
+    switch (instr->conditionField()) {
+      case Assembler::EQ: return z_flag_;
+      case Assembler::NE: return !z_flag_;
+      case Assembler::CS: return c_flag_;
+      case Assembler::CC: return !c_flag_;
+      case Assembler::MI: return n_flag_;
+      case Assembler::PL: return !n_flag_;
+      case Assembler::VS: return v_flag_;
+      case Assembler::VC: return !v_flag_;
+      case Assembler::HI: return c_flag_ && !z_flag_;
+      case Assembler::LS: return !c_flag_ || z_flag_;
+      case Assembler::GE: return n_flag_ == v_flag_;
+      case Assembler::LT: return n_flag_ != v_flag_;
+      case Assembler::GT: return !z_flag_ && (n_flag_ == v_flag_);
+      case Assembler::LE: return z_flag_ || (n_flag_ != v_flag_);
+      case Assembler::AL: return true;
+      default: MOZ_CRASH();
+    }
+    return false;
+}
+
+// Calculate and set the Negative and Zero flags.
+void
+Simulator::setNZFlags(int32_t val)
+{
+    n_flag_ = (val < 0);
+    z_flag_ = (val == 0);
+}
+
+// Set the Carry flag.
+void
+Simulator::setCFlag(bool val)
+{
+    c_flag_ = val;
+}
+
+// Set the oVerflow flag.
+void
+Simulator::setVFlag(bool val)
+{
+    v_flag_ = val;
+}
+
+// Calculate C flag value for additions.
+bool
+Simulator::carryFrom(int32_t left, int32_t right, int32_t carry)
+{
+    uint32_t uleft = static_cast<uint32_t>(left);
+    uint32_t uright = static_cast<uint32_t>(right);
+    uint32_t urest  = 0xffffffffU - uleft;
+    return (uright > urest) ||
+           (carry && (((uright + 1) > urest) || (uright > (urest - 1))));
+}
+
+// Calculate C flag value for subtractions.
+bool
+Simulator::borrowFrom(int32_t left, int32_t right)
+{
+    uint32_t uleft = static_cast<uint32_t>(left);
+    uint32_t uright = static_cast<uint32_t>(right);
+    return (uright > uleft);
+}
+
+// Calculate V flag value for additions and subtractions.
+bool
+Simulator::overflowFrom(int32_t alu_out, int32_t left, int32_t right, bool addition)
+{
+    bool overflow;
+    if (addition) {
+        // Operands have the same sign.
+        overflow = ((left >= 0 && right >= 0) || (left < 0 && right < 0))
+            // And operands and result have different sign.
+            && ((left < 0 && alu_out >= 0) || (left >= 0 && alu_out < 0));
+    } else {
+        // Operands have different signs.
+        overflow = ((left < 0 && right >= 0) || (left >= 0 && right < 0))
+            // And first operand and result have different signs.
+            && ((left < 0 && alu_out >= 0) || (left >= 0 && alu_out < 0));
+    }
+    return overflow;
+}
+
+// Support for VFP comparisons.
+void
+Simulator::compute_FPSCR_Flags(double val1, double val2)
+{
+    if (mozilla::IsNaN(val1) || mozilla::IsNaN(val2)) {
+        n_flag_FPSCR_ = false;
+        z_flag_FPSCR_ = false;
+        c_flag_FPSCR_ = true;
+        v_flag_FPSCR_ = true;
+        // All non-NaN cases.
+    } else if (val1 == val2) {
+        n_flag_FPSCR_ = false;
+        z_flag_FPSCR_ = true;
+        c_flag_FPSCR_ = true;
+        v_flag_FPSCR_ = false;
+    } else if (val1 < val2) {
+        n_flag_FPSCR_ = true;
+        z_flag_FPSCR_ = false;
+        c_flag_FPSCR_ = false;
+        v_flag_FPSCR_ = false;
+    } else {
+        // Case when (val1 > val2).
+        n_flag_FPSCR_ = false;
+        z_flag_FPSCR_ = false;
+        c_flag_FPSCR_ = true;
+        v_flag_FPSCR_ = false;
+    }
+}
+
+void
+Simulator::copy_FPSCR_to_APSR()
+{
+    n_flag_ = n_flag_FPSCR_;
+    z_flag_ = z_flag_FPSCR_;
+    c_flag_ = c_flag_FPSCR_;
+    v_flag_ = v_flag_FPSCR_;
+}
+
+// Addressing Mode 1 - Data-processing operands:
+// Get the value based on the shifter_operand with register.
+int32_t
+Simulator::getShiftRm(SimInstruction* instr, bool* carry_out)
+{
+    ShiftType shift = instr->shifttypeValue();
+    int shift_amount = instr->shiftAmountValue();
+    int32_t result = get_register(instr->rmValue());
+    if (instr->bit(4) == 0) {
+        // By immediate.
+        if (shift == ROR && shift_amount == 0) {
+            MOZ_CRASH("NYI");
+            return result;
+        }
+        if ((shift == LSR || shift == ASR) && shift_amount == 0)
+            shift_amount = 32;
+        switch (shift) {
+          case ASR: {
+            if (shift_amount == 0) {
+                if (result < 0) {
+                    result = 0xffffffff;
+                    *carry_out = true;
+                } else {
+                    result = 0;
+                    *carry_out = false;
+                }
+            } else {
+                result >>= (shift_amount - 1);
+                *carry_out = (result & 1) == 1;
+                result >>= 1;
+            }
+            break;
+          }
+
+          case LSL: {
+            if (shift_amount == 0) {
+                *carry_out = c_flag_;
+            } else {
+                result <<= (shift_amount - 1);
+                *carry_out = (result < 0);
+                result <<= 1;
+            }
+            break;
+          }
+
+          case LSR: {
+            if (shift_amount == 0) {
+                result = 0;
+                *carry_out = c_flag_;
+            } else {
+                uint32_t uresult = static_cast<uint32_t>(result);
+                uresult >>= (shift_amount - 1);
+                *carry_out = (uresult & 1) == 1;
+                uresult >>= 1;
+                result = static_cast<int32_t>(uresult);
+            }
+            break;
+          }
+
+          case ROR: {
+            if (shift_amount == 0) {
+                *carry_out = c_flag_;
+            } else {
+                uint32_t left = static_cast<uint32_t>(result) >> shift_amount;
+                uint32_t right = static_cast<uint32_t>(result) << (32 - shift_amount);
+                result = right | left;
+                *carry_out = (static_cast<uint32_t>(result) >> 31) != 0;
+            }
+            break;
+          }
+
+          default:
+            MOZ_CRASH();
+        }
+    } else {
+        // By register.
+        int rs = instr->rsValue();
+        shift_amount = get_register(rs) &0xff;
+        switch (shift) {
+          case ASR: {
+            if (shift_amount == 0) {
+                *carry_out = c_flag_;
+            } else if (shift_amount < 32) {
+                result >>= (shift_amount - 1);
+                *carry_out = (result & 1) == 1;
+                result >>= 1;
+            } else {
+                MOZ_ASSERT(shift_amount >= 32);
+                if (result < 0) {
+                    *carry_out = true;
+                    result = 0xffffffff;
+                } else {
+                    *carry_out = false;
+                    result = 0;
+                }
+            }
+            break;
+          }
+
+          case LSL: {
+            if (shift_amount == 0) {
+                *carry_out = c_flag_;
+            } else if (shift_amount < 32) {
+                result <<= (shift_amount - 1);
+                *carry_out = (result < 0);
+                result <<= 1;
+            } else if (shift_amount == 32) {
+                *carry_out = (result & 1) == 1;
+                result = 0;
+            } else {
+                MOZ_ASSERT(shift_amount > 32);
+                *carry_out = false;
+                result = 0;
+            }
+            break;
+          }
+
+          case LSR: {
+            if (shift_amount == 0) {
+                *carry_out = c_flag_;
+            } else if (shift_amount < 32) {
+                uint32_t uresult = static_cast<uint32_t>(result);
+                uresult >>= (shift_amount - 1);
+                *carry_out = (uresult & 1) == 1;
+                uresult >>= 1;
+                result = static_cast<int32_t>(uresult);
+            } else if (shift_amount == 32) {
+                *carry_out = (result < 0);
+                result = 0;
+            } else {
+                *carry_out = false;
+                result = 0;
+            }
+            break;
+          }
+
+          case ROR: {
+            if (shift_amount == 0) {
+                *carry_out = c_flag_;
+            } else {
+                uint32_t left = static_cast<uint32_t>(result) >> shift_amount;
+                uint32_t right = static_cast<uint32_t>(result) << (32 - shift_amount);
+                result = right | left;
+                *carry_out = (static_cast<uint32_t>(result) >> 31) != 0;
+            }
+            break;
+          }
+
+          default:
+            MOZ_CRASH();
+        }
+    }
+    return result;
+}
+
+// Addressing Mode 1 - Data-processing operands:
+// Get the value based on the shifter_operand with immediate.
+int32_t
+Simulator::getImm(SimInstruction* instr, bool* carry_out)
+{
+    int rotate = instr->rotateValue() * 2;
+    int immed8 = instr->immed8Value();
+    int imm = (immed8 >> rotate) | (immed8 << (32 - rotate));
+    *carry_out = (rotate == 0) ? c_flag_ : (imm < 0);
+    return imm;
+}
+
+int32_t
+Simulator::processPU(SimInstruction* instr, int num_regs, int reg_size,
+                     intptr_t* start_address, intptr_t* end_address)
+{
+    int rn = instr->rnValue();
+    int32_t rn_val = get_register(rn);
+    switch (instr->PUField()) {
+      case da_x:
+        MOZ_CRASH();
+        break;
+      case ia_x:
+        *start_address = rn_val;
+        *end_address = rn_val + (num_regs * reg_size) - reg_size;
+        rn_val = rn_val + (num_regs * reg_size);
+        break;
+      case db_x:
+        *start_address = rn_val - (num_regs * reg_size);
+        *end_address = rn_val - reg_size;
+        rn_val = *start_address;
+        break;
+      case ib_x:
+        *start_address = rn_val + reg_size;
+        *end_address = rn_val + (num_regs * reg_size);
+        rn_val = *end_address;
+        break;
+      default:
+        MOZ_CRASH();
+    }
+    return rn_val;
+}
+
+// Addressing Mode 4 - Load and Store Multiple
+void
+Simulator::handleRList(SimInstruction* instr, bool load)
+{
+    int rlist = instr->rlistValue();
+    int num_regs = mozilla::CountPopulation32(rlist);
+
+    intptr_t start_address = 0;
+    intptr_t end_address = 0;
+    int32_t rn_val = processPU(instr, num_regs, sizeof(void*), &start_address, &end_address);
+    intptr_t* address = reinterpret_cast<intptr_t*>(start_address);
+
+    // Catch null pointers a little earlier.
+    MOZ_ASSERT(start_address > 8191 || start_address < 0);
+
+    int reg = 0;
+    while (rlist != 0) {
+        if ((rlist & 1) != 0) {
+            if (load) {
+                set_register(reg, *address);
+            } else {
+                *address = get_register(reg);
+            }
+            address += 1;
+        }
+        reg++;
+        rlist >>= 1;
+    }
+    MOZ_ASSERT(end_address == ((intptr_t)address) - 4);
+    if (instr->hasW())
+        set_register(instr->rnValue(), rn_val);
+}
+
+// Addressing Mode 6 - Load and Store Multiple Coprocessor registers.
+void
+Simulator::handleVList(SimInstruction* instr)
+{
+    VFPRegPrecision precision = (instr->szValue() == 0) ? kSinglePrecision : kDoublePrecision;
+    int operand_size = (precision == kSinglePrecision) ? 4 : 8;
+    bool load = (instr->VLValue() == 0x1);
+
+    int vd;
+    int num_regs;
+    vd = instr->VFPDRegValue(precision);
+    if (precision == kSinglePrecision)
+        num_regs = instr->immed8Value();
+    else
+        num_regs = instr->immed8Value() / 2;
+
+    intptr_t start_address = 0;
+    intptr_t end_address = 0;
+    int32_t rn_val = processPU(instr, num_regs, operand_size, &start_address, &end_address);
+
+    intptr_t* address = reinterpret_cast<intptr_t*>(start_address);
+    for (int reg = vd; reg < vd + num_regs; reg++) {
+        if (precision == kSinglePrecision) {
+            if (load)
+                set_s_register_from_sinteger(reg, readW(reinterpret_cast<int32_t>(address), instr));
+            else
+                writeW(reinterpret_cast<int32_t>(address), get_sinteger_from_s_register(reg), instr);
+            address += 1;
+        } else {
+            if (load) {
+                int32_t data[] = {
+                    readW(reinterpret_cast<int32_t>(address), instr),
+                    readW(reinterpret_cast<int32_t>(address + 1), instr)
+                };
+                double d;
+                memcpy(&d, data, 8);
+                set_d_register_from_double(reg, d);
+            } else {
+                int32_t data[2];
+                double d;
+                get_double_from_d_register(reg, &d);
+                memcpy(data, &d, 8);
+                writeW(reinterpret_cast<int32_t>(address), data[0], instr);
+                writeW(reinterpret_cast<int32_t>(address + 1), data[1], instr);
+            }
+            address += 2;
+        }
+    }
+    MOZ_ASSERT(reinterpret_cast<intptr_t>(address) - operand_size == end_address);
+    if (instr->hasW())
+        set_register(instr->rnValue(), rn_val);
+}
+
+
+// Note: With the code below we assume that all runtime calls return a 64 bits
+// result. If they don't, the r1 result register contains a bogus value, which
+// is fine because it is caller-saved.
+typedef int64_t (*Prototype_General0)();
+typedef int64_t (*Prototype_General1)(int32_t arg0);
+typedef int64_t (*Prototype_General2)(int32_t arg0, int32_t arg1);
+typedef int64_t (*Prototype_General3)(int32_t arg0, int32_t arg1, int32_t arg2);
+typedef int64_t (*Prototype_General4)(int32_t arg0, int32_t arg1, int32_t arg2, int32_t arg3);
+typedef int64_t (*Prototype_General5)(int32_t arg0, int32_t arg1, int32_t arg2, int32_t arg3,
+                                      int32_t arg4);
+typedef int64_t (*Prototype_General6)(int32_t arg0, int32_t arg1, int32_t arg2, int32_t arg3,
+                                      int32_t arg4, int32_t arg5);
+typedef int64_t (*Prototype_General7)(int32_t arg0, int32_t arg1, int32_t arg2, int32_t arg3,
+                                      int32_t arg4, int32_t arg5, int32_t arg6);
+typedef int64_t (*Prototype_General8)(int32_t arg0, int32_t arg1, int32_t arg2, int32_t arg3,
+                                      int32_t arg4, int32_t arg5, int32_t arg6, int32_t arg7);
+
+typedef double (*Prototype_Double_None)();
+typedef double (*Prototype_Double_Double)(double arg0);
+typedef double (*Prototype_Double_Int)(int32_t arg0);
+typedef double (*Prototype_Double_IntInt)(int32_t arg0, int32_t arg1);
+typedef int32_t (*Prototype_Int_Double)(double arg0);
+typedef int64_t (*Prototype_Int64_Double)(double arg0);
+typedef int32_t (*Prototype_Int_DoubleIntInt)(double arg0, int32_t arg1, int32_t arg2);
+typedef int32_t (*Prototype_Int_IntDoubleIntInt)(int32_t arg0, double arg1, int32_t arg2,
+                                                 int32_t arg3);
+typedef float (*Prototype_Float32_Float32)(float arg0);
+
+typedef double (*Prototype_DoubleInt)(double arg0, int32_t arg1);
+typedef double (*Prototype_Double_IntDouble)(int32_t arg0, double arg1);
+typedef double (*Prototype_Double_DoubleDouble)(double arg0, double arg1);
+typedef int32_t (*Prototype_Int_IntDouble)(int32_t arg0, double arg1);
+
+typedef double (*Prototype_Double_DoubleDoubleDouble)(double arg0, double arg1, double arg2);
+typedef double (*Prototype_Double_DoubleDoubleDoubleDouble)(double arg0, double arg1,
+                                                            double arg2, double arg3);
+
+// Fill the volatile registers with scratch values.
+//
+// Some of the ABI calls assume that the float registers are not scratched, even
+// though the ABI defines them as volatile - a performance optimization. These
+// are all calls passing operands in integer registers, so for now the simulator
+// does not scratch any float registers for these calls. Should try to narrow it
+// further in future.
+//
+void
+Simulator::scratchVolatileRegisters(bool scratchFloat)
+{
+    int32_t scratch_value = 0xa5a5a5a5 ^ uint32_t(icount_);
+    set_register(r0, scratch_value);
+    set_register(r1, scratch_value);
+    set_register(r2, scratch_value);
+    set_register(r3, scratch_value);
+    set_register(r12, scratch_value); // Intra-Procedure-call scratch register.
+    set_register(r14, scratch_value); // Link register.
+
+    if (scratchFloat) {
+        uint64_t scratch_value_d = 0x5a5a5a5a5a5a5a5aLU ^ uint64_t(icount_) ^ (uint64_t(icount_) << 30);
+        for (uint32_t i = d0; i < d8; i++)
+            set_d_register(i, &scratch_value_d);
+        for (uint32_t i = d16; i < FloatRegisters::TotalPhys; i++)
+            set_d_register(i, &scratch_value_d);
+    }
+}
+
+// Software interrupt instructions are used by the simulator to call into C++.
+void
+Simulator::softwareInterrupt(SimInstruction* instr)
+{
+    int svc = instr->svcValue();
+    switch (svc) {
+      case kCallRtRedirected: {
+        Redirection* redirection = Redirection::FromSwiInstruction(instr);
+        int32_t arg0 = get_register(r0);
+        int32_t arg1 = get_register(r1);
+        int32_t arg2 = get_register(r2);
+        int32_t arg3 = get_register(r3);
+        int32_t* stack_pointer = reinterpret_cast<int32_t*>(get_register(sp));
+        int32_t arg4 = stack_pointer[0];
+        int32_t arg5 = stack_pointer[1];
+
+        int32_t saved_lr = get_register(lr);
+        intptr_t external = reinterpret_cast<intptr_t>(redirection->nativeFunction());
+
+        bool stack_aligned = (get_register(sp) & (ABIStackAlignment - 1)) == 0;
+        if (!stack_aligned) {
+            fprintf(stderr, "Runtime call with unaligned stack!\n");
+            MOZ_CRASH();
+        }
+
+        if (single_stepping_)
+            single_step_callback_(single_step_callback_arg_, this, nullptr);
+
+        switch (redirection->type()) {
+          case Args_General0: {
+            Prototype_General0 target = reinterpret_cast<Prototype_General0>(external);
+            int64_t result = target();
+            scratchVolatileRegisters(/* scratchFloat = true */);
+            setCallResult(result);
+            break;
+          }
+          case Args_General1: {
+            Prototype_General1 target = reinterpret_cast<Prototype_General1>(external);
+            int64_t result = target(arg0);
+            scratchVolatileRegisters(/* scratchFloat = true */);
+            setCallResult(result);
+            break;
+          }
+          case Args_General2: {
+            Prototype_General2 target = reinterpret_cast<Prototype_General2>(external);
+            int64_t result = target(arg0, arg1);
+            // The ARM backend makes calls to __aeabi_idivmod and
+            // __aeabi_uidivmod assuming that the float registers are
+            // non-volatile as a performance optimization, so the float
+            // registers must not be scratch when calling these.
+            bool scratchFloat = target != __aeabi_idivmod && target != __aeabi_uidivmod;
+            scratchVolatileRegisters(/* scratchFloat = */ scratchFloat);
+            setCallResult(result);
+            break;
+          }
+          case Args_General3: {
+            Prototype_General3 target = reinterpret_cast<Prototype_General3>(external);
+            int64_t result = target(arg0, arg1, arg2);
+            scratchVolatileRegisters(/* scratchFloat = true*/);
+            setCallResult(result);
+            break;
+          }
+          case Args_General4: {
+            Prototype_General4 target = reinterpret_cast<Prototype_General4>(external);
+            int64_t result = target(arg0, arg1, arg2, arg3);
+            scratchVolatileRegisters(/* scratchFloat = true*/);
+            setCallResult(result);
+            break;
+          }
+          case Args_General5: {
+            Prototype_General5 target = reinterpret_cast<Prototype_General5>(external);
+            int64_t result = target(arg0, arg1, arg2, arg3, arg4);
+            scratchVolatileRegisters(/* scratchFloat = true */);
+            setCallResult(result);
+            break;
+          }
+          case Args_General6: {
+            Prototype_General6 target = reinterpret_cast<Prototype_General6>(external);
+            int64_t result = target(arg0, arg1, arg2, arg3, arg4, arg5);
+            scratchVolatileRegisters(/* scratchFloat = true */);
+            setCallResult(result);
+            break;
+          }
+          case Args_General7: {
+            Prototype_General7 target = reinterpret_cast<Prototype_General7>(external);
+            int32_t arg6 = stack_pointer[2];
+            int64_t result = target(arg0, arg1, arg2, arg3, arg4, arg5, arg6);
+            scratchVolatileRegisters(/* scratchFloat = true */);
+            setCallResult(result);
+            break;
+          }
+          case Args_General8: {
+            Prototype_General8 target = reinterpret_cast<Prototype_General8>(external);
+            int32_t arg6 = stack_pointer[2];
+            int32_t arg7 = stack_pointer[3];
+            int64_t result = target(arg0, arg1, arg2, arg3, arg4, arg5, arg6, arg7);
+            scratchVolatileRegisters(/* scratchFloat = true */);
+            setCallResult(result);
+            break;
+          }
+          case Args_Int64_Double: {
+            double dval0, dval1;
+            int32_t ival;
+            getFpArgs(&dval0, &dval1, &ival);
+            Prototype_Int64_Double target = reinterpret_cast<Prototype_Int64_Double>(external);
+            int64_t result = target(dval0);
+            scratchVolatileRegisters(/* scratchFloat = true */);
+            setCallResult(result);
+            break;
+          }
+          case Args_Double_None: {
+            Prototype_Double_None target = reinterpret_cast<Prototype_Double_None>(external);
+            double dresult = target();
+            scratchVolatileRegisters(/* scratchFloat = true */);
+            setCallResultDouble(dresult);
+            break;
+          }
+          case Args_Int_Double: {
+            double dval0, dval1;
+            int32_t ival;
+            getFpArgs(&dval0, &dval1, &ival);
+            Prototype_Int_Double target = reinterpret_cast<Prototype_Int_Double>(external);
+            int32_t res = target(dval0);
+            scratchVolatileRegisters(/* scratchFloat = true */);
+            set_register(r0, res);
+            break;
+          }
+          case Args_Double_Double: {
+            double dval0, dval1;
+            int32_t ival;
+            getFpArgs(&dval0, &dval1, &ival);
+            Prototype_Double_Double target = reinterpret_cast<Prototype_Double_Double>(external);
+            double dresult = target(dval0);
+            scratchVolatileRegisters(/* scratchFloat = true */);
+            setCallResultDouble(dresult);
+            break;
+          }
+          case Args_Float32_Float32: {
+            float fval0;
+            if (UseHardFpABI())
+                get_float_from_s_register(0, &fval0);
+            else
+                fval0 = mozilla::BitwiseCast<float>(arg0);
+            Prototype_Float32_Float32 target = reinterpret_cast<Prototype_Float32_Float32>(external);
+            float fresult = target(fval0);
+            scratchVolatileRegisters(/* scratchFloat = true */);
+            setCallResultFloat(fresult);
+            break;
+          }
+          case Args_Double_Int: {
+            Prototype_Double_Int target = reinterpret_cast<Prototype_Double_Int>(external);
+            double dresult = target(arg0);
+            scratchVolatileRegisters(/* scratchFloat = true */);
+            setCallResultDouble(dresult);
+            break;
+          }
+          case Args_Double_IntInt: {
+            Prototype_Double_IntInt target = reinterpret_cast<Prototype_Double_IntInt>(external);
+            double dresult = target(arg0, arg1);
+            scratchVolatileRegisters(/* scratchFloat = true */);
+            setCallResultDouble(dresult);
+            break;
+          }
+          case Args_Double_DoubleInt: {
+            double dval0, dval1;
+            int32_t ival;
+            getFpArgs(&dval0, &dval1, &ival);
+            Prototype_DoubleInt target = reinterpret_cast<Prototype_DoubleInt>(external);
+            double dresult = target(dval0, ival);
+            scratchVolatileRegisters(/* scratchFloat = true */);
+            setCallResultDouble(dresult);
+            break;
+          }
+          case Args_Double_DoubleDouble: {
+            double dval0, dval1;
+            int32_t ival;
+            getFpArgs(&dval0, &dval1, &ival);
+            Prototype_Double_DoubleDouble target = reinterpret_cast<Prototype_Double_DoubleDouble>(external);
+            double dresult = target(dval0, dval1);
+            scratchVolatileRegisters(/* scratchFloat = true */);
+            setCallResultDouble(dresult);
+            break;
+          }
+          case Args_Double_IntDouble: {
+            int32_t ival = get_register(0);
+            double dval0;
+            if (UseHardFpABI())
+                get_double_from_d_register(0, &dval0);
+            else
+                dval0 = get_double_from_register_pair(2);
+            Prototype_Double_IntDouble target = reinterpret_cast<Prototype_Double_IntDouble>(external);
+            double dresult = target(ival, dval0);
+            scratchVolatileRegisters(/* scratchFloat = true */);
+            setCallResultDouble(dresult);
+            break;
+          }
+          case Args_Int_IntDouble: {
+            int32_t ival = get_register(0);
+            double dval0;
+            if (UseHardFpABI())
+                get_double_from_d_register(0, &dval0);
+            else
+                dval0 = get_double_from_register_pair(2);
+            Prototype_Int_IntDouble target = reinterpret_cast<Prototype_Int_IntDouble>(external);
+            int32_t result = target(ival, dval0);
+            scratchVolatileRegisters(/* scratchFloat = true */);
+            set_register(r0, result);
+            break;
+          }
+          case Args_Int_DoubleIntInt: {
+            double dval;
+            int32_t result;
+            Prototype_Int_DoubleIntInt target = reinterpret_cast<Prototype_Int_DoubleIntInt>(external);
+            if (UseHardFpABI()) {
+                get_double_from_d_register(0, &dval);
+                result = target(dval, arg0, arg1);
+            } else {
+                dval = get_double_from_register_pair(0);
+                result = target(dval, arg2, arg3);
+            }
+            scratchVolatileRegisters(/* scratchFloat = true */);
+            set_register(r0, result);
+            break;
+          }
+          case Args_Int_IntDoubleIntInt: {
+            double dval;
+            int32_t result;
+            Prototype_Int_IntDoubleIntInt target = reinterpret_cast<Prototype_Int_IntDoubleIntInt>(external);
+            if (UseHardFpABI()) {
+                get_double_from_d_register(0, &dval);
+                result = target(arg0, dval, arg1, arg2);
+            } else {
+                dval = get_double_from_register_pair(2);
+                result = target(arg0, dval, arg4, arg5);
+            }
+            scratchVolatileRegisters(/* scratchFloat = true */);
+            set_register(r0, result);
+            break;
+          }
+          case Args_Double_DoubleDoubleDouble: {
+            double dval0, dval1, dval2;
+            int32_t ival;
+            getFpArgs(&dval0, &dval1, &ival);
+            // the last argument is on stack
+            getFpFromStack(stack_pointer, &dval2);
+            Prototype_Double_DoubleDoubleDouble target = reinterpret_cast<Prototype_Double_DoubleDoubleDouble>(external);
+            double dresult = target(dval0, dval1, dval2);
+            scratchVolatileRegisters(/* scratchFloat = true */);
+            setCallResultDouble(dresult);
+            break;
+         }
+         case Args_Double_DoubleDoubleDoubleDouble: {
+            double dval0, dval1, dval2, dval3;
+            int32_t ival;
+            getFpArgs(&dval0, &dval1, &ival);
+            // the two last arguments are on stack
+            getFpFromStack(stack_pointer, &dval2);
+            getFpFromStack(stack_pointer + 2, &dval3);
+            Prototype_Double_DoubleDoubleDoubleDouble target = reinterpret_cast<Prototype_Double_DoubleDoubleDoubleDouble>(external);
+            double dresult = target(dval0, dval1, dval2, dval3);
+            scratchVolatileRegisters(/* scratchFloat = true */);
+            setCallResultDouble(dresult);
+            break;
+          }
+          default:
+            MOZ_CRASH("call");
+        }
+
+        if (single_stepping_)
+            single_step_callback_(single_step_callback_arg_, this, nullptr);
+
+        set_register(lr, saved_lr);
+        set_pc(get_register(lr));
+        break;
+      }
+      case kBreakpoint: {
+        ArmDebugger dbg(this);
+        dbg.debug();
+        break;
+      }
+      default: { // Stop uses all codes greater than 1 << 23.
+        if (svc >= (1 << 23)) {
+            uint32_t code = svc & kStopCodeMask;
+            if (isWatchedStop(code))
+                increaseStopCounter(code);
+
+            // Stop if it is enabled, otherwise go on jumping over the stop and
+            // the message address.
+            if (isEnabledStop(code)) {
+                ArmDebugger dbg(this);
+                dbg.stop(instr);
+            } else {
+                set_pc(get_pc() + 2 * SimInstruction::kInstrSize);
+            }
+        } else {
+            // This is not a valid svc code.
+            MOZ_CRASH();
+            break;
+        }
+      }
+    }
+}
+
+void
+Simulator::canonicalizeNaN(double* value)
+{
+    if (!JitOptions.wasmTestMode && FPSCR_default_NaN_mode_)
+        *value = JS::CanonicalizeNaN(*value);
+}
+
+void
+Simulator::canonicalizeNaN(float* value)
+{
+    if (!JitOptions.wasmTestMode && FPSCR_default_NaN_mode_)
+        *value = JS::CanonicalizeNaN(*value);
+}
+
+// Stop helper functions.
+bool
+Simulator::isStopInstruction(SimInstruction* instr)
+{
+    return (instr->bits(27, 24) == 0xF) && (instr->svcValue() >= kStopCode);
+}
+
+bool Simulator::isWatchedStop(uint32_t code)
+{
+    MOZ_ASSERT(code <= kMaxStopCode);
+    return code < kNumOfWatchedStops;
+}
+
+bool
+Simulator::isEnabledStop(uint32_t code)
+{
+    MOZ_ASSERT(code <= kMaxStopCode);
+    // Unwatched stops are always enabled.
+    return !isWatchedStop(code) || !(watched_stops_[code].count & kStopDisabledBit);
+}
+
+void
+Simulator::enableStop(uint32_t code)
+{
+    MOZ_ASSERT(isWatchedStop(code));
+    if (!isEnabledStop(code))
+        watched_stops_[code].count &= ~kStopDisabledBit;
+}
+
+void
+Simulator::disableStop(uint32_t code)
+{
+    MOZ_ASSERT(isWatchedStop(code));
+    if (isEnabledStop(code))
+        watched_stops_[code].count |= kStopDisabledBit;
+}
+
+void
+Simulator::increaseStopCounter(uint32_t code)
+{
+    MOZ_ASSERT(code <= kMaxStopCode);
+    MOZ_ASSERT(isWatchedStop(code));
+    if ((watched_stops_[code].count & ~(1 << 31)) == 0x7fffffff) {
+        printf("Stop counter for code %i has overflowed.\n"
+               "Enabling this code and reseting the counter to 0.\n", code);
+        watched_stops_[code].count = 0;
+        enableStop(code);
+    } else {
+        watched_stops_[code].count++;
+    }
+}
+
+// Print a stop status.
+void
+Simulator::printStopInfo(uint32_t code)
+{
+    MOZ_ASSERT(code <= kMaxStopCode);
+    if (!isWatchedStop(code)) {
+        printf("Stop not watched.");
+    } else {
+        const char* state = isEnabledStop(code) ? "Enabled" : "Disabled";
+        int32_t count = watched_stops_[code].count & ~kStopDisabledBit;
+        // Don't print the state of unused breakpoints.
+        if (count != 0) {
+            if (watched_stops_[code].desc) {
+                printf("stop %i - 0x%x: \t%s, \tcounter = %i, \t%s\n",
+                       code, code, state, count, watched_stops_[code].desc);
+            } else {
+                printf("stop %i - 0x%x: \t%s, \tcounter = %i\n",
+                       code, code, state, count);
+            }
+        }
+    }
+}
+
+// Instruction types 0 and 1 are both rolled into one function because they only
+// differ in the handling of the shifter_operand.
+void
+Simulator::decodeType01(SimInstruction* instr)
+{
+    int type = instr->typeValue();
+    if (type == 0 && instr->isSpecialType0()) {
+        // Multiply instruction or extra loads and stores.
+        if (instr->bits(7, 4) == 9) {
+            if (instr->bit(24) == 0) {
+                // Raw field decoding here. Multiply instructions have their Rd
+                // in funny places.
+                int rn = instr->rnValue();
+                int rm = instr->rmValue();
+                int rs = instr->rsValue();
+                int32_t rs_val = get_register(rs);
+                int32_t rm_val = get_register(rm);
+                if (instr->bit(23) == 0) {
+                    if (instr->bit(21) == 0) {
+                        // The MUL instruction description (A 4.1.33) refers to
+                        // Rd as being the destination for the operation, but it
+                        // confusingly uses the Rn field to encode it.
+                        int rd = rn;  // Remap the rn field to the Rd register.
+                        int32_t alu_out = rm_val * rs_val;
+                        set_register(rd, alu_out);
+                        if (instr->hasS())
+                            setNZFlags(alu_out);
+                    } else {
+                        int rd = instr->rdValue();
+                        int32_t acc_value = get_register(rd);
+                        if (instr->bit(22) == 0) {
+                            // The MLA instruction description (A 4.1.28) refers
+                            // to the order of registers as "Rd, Rm, Rs,
+                            // Rn". But confusingly it uses the Rn field to
+                            // encode the Rd register and the Rd field to encode
+                            // the Rn register.
+                            int32_t mul_out = rm_val * rs_val;
+                            int32_t result = acc_value + mul_out;
+                            set_register(rn, result);
+                        } else {
+                            int32_t mul_out = rm_val * rs_val;
+                            int32_t result = acc_value - mul_out;
+                            set_register(rn, result);
+                        }
+                    }
+                } else {
+                    // The signed/long multiply instructions use the terms RdHi
+                    // and RdLo when referring to the target registers. They are
+                    // mapped to the Rn and Rd fields as follows:
+                    // RdLo == Rd
+                    // RdHi == Rn (This is confusingly stored in variable rd here
+                    //             because the mul instruction from above uses the
+                    //             Rn field to encode the Rd register. Good luck figuring
+                    //             this out without reading the ARM instruction manual
+                    //             at a very detailed level.)
+                    int rd_hi = rn;  // Remap the rn field to the RdHi register.
+                    int rd_lo = instr->rdValue();
+                    int32_t hi_res = 0;
+                    int32_t lo_res = 0;
+                    if (instr->bit(22) == 1) {
+                        int64_t left_op  = static_cast<int32_t>(rm_val);
+                        int64_t right_op = static_cast<int32_t>(rs_val);
+                        uint64_t result = left_op * right_op;
+                        hi_res = static_cast<int32_t>(result >> 32);
+                        lo_res = static_cast<int32_t>(result & 0xffffffff);
+                    } else {
+                        // Unsigned multiply.
+                        uint64_t left_op  = static_cast<uint32_t>(rm_val);
+                        uint64_t right_op = static_cast<uint32_t>(rs_val);
+                        uint64_t result = left_op * right_op;
+                        hi_res = static_cast<int32_t>(result >> 32);
+                        lo_res = static_cast<int32_t>(result & 0xffffffff);
+                    }
+                    set_register(rd_lo, lo_res);
+                    set_register(rd_hi, hi_res);
+                    if (instr->hasS())
+                        MOZ_CRASH();
+                }
+            } else {
+                if (instr->bits(disasm::ExclusiveOpHi, disasm::ExclusiveOpLo) == disasm::ExclusiveOpcode) {
+                    // Load-exclusive / store-exclusive.
+                    if (instr->bit(disasm::ExclusiveLoad)) {
+                        int rn = instr->rnValue();
+                        int rt = instr->rtValue();
+                        int32_t address = get_register(rn);
+                        switch (instr->bits(disasm::ExclusiveSizeHi, disasm::ExclusiveSizeLo)) {
+                          case disasm::ExclusiveWord:
+                            set_register(rt, readExW(address, instr));
+                            break;
+                          case disasm::ExclusiveDouble: {
+                            MOZ_ASSERT((rt % 2) == 0);
+                            int32_t hibits;
+                            int32_t lobits = readExDW(address, &hibits);
+                            set_register(rt, lobits);
+                            set_register(rt+1, hibits);
+                            break;
+                          }
+                          case disasm::ExclusiveByte:
+                            set_register(rt, readExBU(address));
+                            break;
+                          case disasm::ExclusiveHalf:
+                            set_register(rt, readExHU(address, instr));
+                            break;
+                        }
+                    } else {
+                        int rn = instr->rnValue();
+                        int rd = instr->rdValue();
+                        int rt = instr->bits(3,0);
+                        int32_t address = get_register(rn);
+                        int32_t value = get_register(rt);
+                        int32_t result = 0;
+                        switch (instr->bits(disasm::ExclusiveSizeHi, disasm::ExclusiveSizeLo)) {
+                          case disasm::ExclusiveWord:
+                            result = writeExW(address, value, instr);
+                            break;
+                          case disasm::ExclusiveDouble: {
+                            MOZ_ASSERT((rt % 2) == 0);
+                            int32_t value2 = get_register(rt+1);
+                            result = writeExDW(address, value, value2);
+                            break;
+                          }
+                          case disasm::ExclusiveByte:
+                            result = writeExB(address, (uint8_t)value);
+                            break;
+                          case disasm::ExclusiveHalf:
+                            result = writeExH(address, (uint16_t)value, instr);
+                            break;
+                        }
+                        set_register(rd, result);
+                    }
+                } else {
+                    MOZ_CRASH(); // Not used atm
+                }
+            }
+        } else {
+            // Extra load/store instructions.
+            int rd = instr->rdValue();
+            int rn = instr->rnValue();
+            int32_t rn_val = get_register(rn);
+            int32_t addr = 0;
+            if (instr->bit(22) == 0) {
+                int rm = instr->rmValue();
+                int32_t rm_val = get_register(rm);
+                switch (instr->PUField()) {
+                  case da_x:
+                    MOZ_ASSERT(!instr->hasW());
+                    addr = rn_val;
+                    rn_val -= rm_val;
+                    set_register(rn, rn_val);
+                    break;
+                  case ia_x:
+                    MOZ_ASSERT(!instr->hasW());
+                    addr = rn_val;
+                    rn_val += rm_val;
+                    set_register(rn, rn_val);
+                    break;
+                  case db_x:
+                    rn_val -= rm_val;
+                    addr = rn_val;
+                    if (instr->hasW())
+                        set_register(rn, rn_val);
+                    break;
+                  case ib_x:
+                    rn_val += rm_val;
+                    addr = rn_val;
+                    if (instr->hasW())
+                        set_register(rn, rn_val);
+                    break;
+                  default:
+                    // The PU field is a 2-bit field.
+                    MOZ_CRASH();
+                    break;
+                }
+            } else {
+                int32_t imm_val = (instr->immedHValue() << 4) | instr->immedLValue();
+                switch (instr->PUField()) {
+                  case da_x:
+                    MOZ_ASSERT(!instr->hasW());
+                    addr = rn_val;
+                    rn_val -= imm_val;
+                    set_register(rn, rn_val);
+                    break;
+                  case ia_x:
+                    MOZ_ASSERT(!instr->hasW());
+                    addr = rn_val;
+                    rn_val += imm_val;
+                    set_register(rn, rn_val);
+                    break;
+                  case db_x:
+                    rn_val -= imm_val;
+                    addr = rn_val;
+                    if (instr->hasW())
+                        set_register(rn, rn_val);
+                    break;
+                  case ib_x:
+                    rn_val += imm_val;
+                    addr = rn_val;
+                    if (instr->hasW())
+                        set_register(rn, rn_val);
+                    break;
+                  default:
+                    // The PU field is a 2-bit field.
+                    MOZ_CRASH();
+                    break;
+                }
+            }
+            if ((instr->bits(7, 4) & 0xd) == 0xd && instr->bit(20) == 0) {
+                MOZ_ASSERT((rd % 2) == 0);
+                if (instr->hasH()) {
+                    // The strd instruction.
+                    int32_t value1 = get_register(rd);
+                    int32_t value2 = get_register(rd+1);
+                    writeDW(addr, value1, value2);
+                } else {
+                    // The ldrd instruction.
+                    int* rn_data = readDW(addr);
+                    set_dw_register(rd, rn_data);
+                }
+            } else if (instr->hasH()) {
+                if (instr->hasSign()) {
+                    if (instr->hasL()) {
+                        int16_t val = readH(addr, instr);
+                        set_register(rd, val);
+                    } else {
+                        int16_t val = get_register(rd);
+                        writeH(addr, val, instr);
+                    }
+                } else {
+                    if (instr->hasL()) {
+                        uint16_t val = readHU(addr, instr);
+                        set_register(rd, val);
+                    } else {
+                        uint16_t val = get_register(rd);
+                        writeH(addr, val, instr);
+                    }
+                }
+            } else {
+                // Signed byte loads.
+                MOZ_ASSERT(instr->hasSign());
+                MOZ_ASSERT(instr->hasL());
+                int8_t val = readB(addr);
+                set_register(rd, val);
+            }
+            return;
+        }
+    } else if ((type == 0) && instr->isMiscType0()) {
+        if (instr->bits(7, 4) == 0) {
+            if (instr->bit(21) == 0) {
+                // mrs
+                int rd = instr->rdValue();
+                uint32_t flags;
+                if (instr->bit(22) == 0) {
+                    // CPSR. Note: The Q flag is not yet implemented!
+                    flags = (n_flag_ << 31) |
+                        (z_flag_ << 30) |
+                        (c_flag_ << 29) |
+                        (v_flag_ << 28);
+                } else {
+                    // SPSR
+                    MOZ_CRASH();
+                }
+                set_register(rd, flags);
+            } else {
+                // msr
+                if (instr->bits(27, 23) == 2) {
+                    // Register operand. For now we only emit mask 0b1100.
+                    int rm = instr->rmValue();
+                    mozilla::DebugOnly<uint32_t> mask = instr->bits(19, 16);
+                    MOZ_ASSERT(mask == (3 << 2));
+
+                    uint32_t flags = get_register(rm);
+                    n_flag_ = (flags >> 31) & 1;
+                    z_flag_ = (flags >> 30) & 1;
+                    c_flag_ = (flags >> 29) & 1;
+                    v_flag_ = (flags >> 28) & 1;
+                } else {
+                    MOZ_CRASH();
+                }
+            }
+        } else if (instr->bits(22, 21) == 1) {
+            int rm = instr->rmValue();
+            switch (instr->bits(7, 4)) {
+              case 1:   // BX
+                set_pc(get_register(rm));
+                break;
+              case 3: { // BLX
+                uint32_t old_pc = get_pc();
+                set_pc(get_register(rm));
+                set_register(lr, old_pc + SimInstruction::kInstrSize);
+                break;
+              }
+              case 7: { // BKPT
+                fprintf(stderr, "Simulator hit BKPT.\n");
+                if (getenv("ARM_SIM_DEBUGGER")) {
+                    ArmDebugger dbg(this);
+                    dbg.debug();
+                } else {
+                    fprintf(stderr, "Use ARM_SIM_DEBUGGER=1 to enter the builtin debugger.\n");
+                    MOZ_CRASH("ARM simulator breakpoint");
+                }
+                break;
+              }
+              default:
+                MOZ_CRASH();
+            }
+        } else if (instr->bits(22, 21) == 3) {
+            int rm = instr->rmValue();
+            int rd = instr->rdValue();
+            switch (instr->bits(7, 4)) {
+              case 1: { // CLZ
+                uint32_t bits = get_register(rm);
+                int leading_zeros = 0;
+                if (bits == 0)
+                    leading_zeros = 32;
+                else
+                    leading_zeros = mozilla::CountLeadingZeroes32(bits);
+                set_register(rd, leading_zeros);
+                break;
+              }
+              default:
+                MOZ_CRASH();
+                break;
+            }
+        } else {
+            printf("%08x\n", instr->instructionBits());
+            MOZ_CRASH();
+        }
+    } else if ((type == 1) && instr->isNopType1()) {
+        // NOP.
+    } else {
+        int rd = instr->rdValue();
+        int rn = instr->rnValue();
+        int32_t rn_val = get_register(rn);
+        int32_t shifter_operand = 0;
+        bool shifter_carry_out = 0;
+        if (type == 0) {
+            shifter_operand = getShiftRm(instr, &shifter_carry_out);
+        } else {
+            MOZ_ASSERT(instr->typeValue() == 1);
+            shifter_operand = getImm(instr, &shifter_carry_out);
+        }
+        int32_t alu_out;
+        switch (instr->opcodeField()) {
+          case OpAnd:
+            alu_out = rn_val & shifter_operand;
+            set_register(rd, alu_out);
+            if (instr->hasS()) {
+                setNZFlags(alu_out);
+                setCFlag(shifter_carry_out);
+            }
+            break;
+          case OpEor:
+            alu_out = rn_val ^ shifter_operand;
+            set_register(rd, alu_out);
+            if (instr->hasS()) {
+                setNZFlags(alu_out);
+                setCFlag(shifter_carry_out);
+            }
+            break;
+          case OpSub:
+            alu_out = rn_val - shifter_operand;
+            set_register(rd, alu_out);
+            if (instr->hasS()) {
+                setNZFlags(alu_out);
+                setCFlag(!borrowFrom(rn_val, shifter_operand));
+                setVFlag(overflowFrom(alu_out, rn_val, shifter_operand, false));
+            }
+            break;
+          case OpRsb:
+            alu_out = shifter_operand - rn_val;
+            set_register(rd, alu_out);
+            if (instr->hasS()) {
+                setNZFlags(alu_out);
+                setCFlag(!borrowFrom(shifter_operand, rn_val));
+                setVFlag(overflowFrom(alu_out, shifter_operand, rn_val, false));
+            }
+            break;
+          case OpAdd:
+            alu_out = rn_val + shifter_operand;
+            set_register(rd, alu_out);
+            if (instr->hasS()) {
+                setNZFlags(alu_out);
+                setCFlag(carryFrom(rn_val, shifter_operand));
+                setVFlag(overflowFrom(alu_out, rn_val, shifter_operand, true));
+            }
+            break;
+          case OpAdc:
+            alu_out = rn_val + shifter_operand + getCarry();
+            set_register(rd, alu_out);
+            if (instr->hasS()) {
+                setNZFlags(alu_out);
+                setCFlag(carryFrom(rn_val, shifter_operand, getCarry()));
+                setVFlag(overflowFrom(alu_out, rn_val, shifter_operand, true));
+            }
+            break;
+          case OpSbc:
+            alu_out = rn_val - shifter_operand - (getCarry() == 0 ? 1 : 0);
+            set_register(rd, alu_out);
+            if (instr->hasS())
+                MOZ_CRASH();
+            break;
+          case OpRsc:
+            alu_out = shifter_operand - rn_val - (getCarry() == 0 ? 1 : 0);
+            set_register(rd, alu_out);
+            if (instr->hasS())
+                MOZ_CRASH();
+            break;
+          case OpTst:
+            if (instr->hasS()) {
+                alu_out = rn_val & shifter_operand;
+                setNZFlags(alu_out);
+                setCFlag(shifter_carry_out);
+            } else {
+                alu_out = instr->immedMovwMovtValue();
+                set_register(rd, alu_out);
+            }
+            break;
+          case OpTeq:
+            if (instr->hasS()) {
+                alu_out = rn_val ^ shifter_operand;
+                setNZFlags(alu_out);
+                setCFlag(shifter_carry_out);
+            } else {
+                // Other instructions matching this pattern are handled in the
+                // miscellaneous instructions part above.
+                MOZ_CRASH();
+            }
+            break;
+          case OpCmp:
+            if (instr->hasS()) {
+                alu_out = rn_val - shifter_operand;
+                setNZFlags(alu_out);
+                setCFlag(!borrowFrom(rn_val, shifter_operand));
+                setVFlag(overflowFrom(alu_out, rn_val, shifter_operand, false));
+            } else {
+                alu_out = (get_register(rd) & 0xffff) |
+                    (instr->immedMovwMovtValue() << 16);
+                set_register(rd, alu_out);
+            }
+            break;
+          case OpCmn:
+            if (instr->hasS()) {
+                alu_out = rn_val + shifter_operand;
+                setNZFlags(alu_out);
+                setCFlag(carryFrom(rn_val, shifter_operand));
+                setVFlag(overflowFrom(alu_out, rn_val, shifter_operand, true));
+            } else {
+                // Other instructions matching this pattern are handled in the
+                // miscellaneous instructions part above.
+                MOZ_CRASH();
+            }
+            break;
+          case OpOrr:
+            alu_out = rn_val | shifter_operand;
+            set_register(rd, alu_out);
+            if (instr->hasS()) {
+                setNZFlags(alu_out);
+                setCFlag(shifter_carry_out);
+            }
+            break;
+          case OpMov:
+            alu_out = shifter_operand;
+            set_register(rd, alu_out);
+            if (instr->hasS()) {
+                setNZFlags(alu_out);
+                setCFlag(shifter_carry_out);
+            }
+            break;
+          case OpBic:
+            alu_out = rn_val & ~shifter_operand;
+            set_register(rd, alu_out);
+            if (instr->hasS()) {
+                setNZFlags(alu_out);
+                setCFlag(shifter_carry_out);
+            }
+            break;
+          case OpMvn:
+            alu_out = ~shifter_operand;
+            set_register(rd, alu_out);
+            if (instr->hasS()) {
+                setNZFlags(alu_out);
+                setCFlag(shifter_carry_out);
+            }
+            break;
+          default:
+            MOZ_CRASH();
+            break;
+        }
+    }
+}
+
+void
+Simulator::decodeType2(SimInstruction* instr)
+{
+    int rd = instr->rdValue();
+    int rn = instr->rnValue();
+    int32_t rn_val = get_register(rn);
+    int32_t im_val = instr->offset12Value();
+    int32_t addr = 0;
+    switch (instr->PUField()) {
+      case da_x:
+        MOZ_ASSERT(!instr->hasW());
+        addr = rn_val;
+        rn_val -= im_val;
+        set_register(rn, rn_val);
+        break;
+      case ia_x:
+        MOZ_ASSERT(!instr->hasW());
+        addr = rn_val;
+        rn_val += im_val;
+        set_register(rn, rn_val);
+        break;
+      case db_x:
+        rn_val -= im_val;
+        addr = rn_val;
+        if (instr->hasW())
+            set_register(rn, rn_val);
+        break;
+      case ib_x:
+        rn_val += im_val;
+        addr = rn_val;
+        if (instr->hasW())
+            set_register(rn, rn_val);
+        break;
+      default:
+        MOZ_CRASH();
+        break;
+    }
+    if (instr->hasB()) {
+        if (instr->hasL()) {
+            uint8_t val = readBU(addr);
+            set_register(rd, val);
+        } else {
+            uint8_t val = get_register(rd);
+            writeB(addr, val);
+        }
+    } else {
+        if (instr->hasL())
+            set_register(rd, readW(addr, instr, AllowUnaligned));
+        else
+            writeW(addr, get_register(rd), instr, AllowUnaligned);
+    }
+}
+
+static uint32_t
+rotateBytes(uint32_t val, int32_t rotate)
+{
+    switch (rotate) {
+      default:
+        return val;
+      case 1:
+        return (val >> 8) | (val << 24);
+      case 2:
+        return (val >> 16) | (val << 16);
+      case 3:
+        return (val >> 24) | (val << 8);
+    }
+}
+
+void
+Simulator::decodeType3(SimInstruction* instr)
+{
+    int rd = instr->rdValue();
+    int rn = instr->rnValue();
+    int32_t rn_val = get_register(rn);
+    bool shifter_carry_out = 0;
+    int32_t shifter_operand = getShiftRm(instr, &shifter_carry_out);
+    int32_t addr = 0;
+    switch (instr->PUField()) {
+      case da_x:
+        MOZ_ASSERT(!instr->hasW());
+        MOZ_CRASH();
+        break;
+      case ia_x: {
+        if (instr->bit(4) == 0) {
+            // Memop.
+        } else {
+            if (instr->bit(5) == 0) {
+                switch (instr->bits(22, 21)) {
+                  case 0:
+                    if (instr->bit(20) == 0) {
+                        if (instr->bit(6) == 0) {
+                            // Pkhbt.
+                            uint32_t rn_val = get_register(rn);
+                            uint32_t rm_val = get_register(instr->rmValue());
+                            int32_t shift = instr->bits(11, 7);
+                            rm_val <<= shift;
+                            set_register(rd, (rn_val & 0xFFFF) | (rm_val & 0xFFFF0000U));
+                        } else {
+                            // Pkhtb.
+                            uint32_t rn_val = get_register(rn);
+                            int32_t rm_val = get_register(instr->rmValue());
+                            int32_t shift = instr->bits(11, 7);
+                            if (shift == 0)
+                                shift = 32;
+                            rm_val >>= shift;
+                            set_register(rd, (rn_val & 0xFFFF0000U) | (rm_val & 0xFFFF));
+                        }
+                    } else {
+                        MOZ_CRASH();
+                    }
+                    break;
+                  case 1:
+                    MOZ_CRASH();
+                    break;
+                  case 2:
+                    MOZ_CRASH();
+                    break;
+                  case 3: {
+                    // Usat.
+                      int32_t sat_pos = instr->bits(20, 16);
+                      int32_t sat_val = (1 << sat_pos) - 1;
+                      int32_t shift = instr->bits(11, 7);
+                      int32_t shift_type = instr->bit(6);
+                      int32_t rm_val = get_register(instr->rmValue());
+                      if (shift_type == 0) // LSL
+                          rm_val <<= shift;
+                      else // ASR
+                          rm_val >>= shift;
+
+                      // If saturation occurs, the Q flag should be set in the
+                      // CPSR. There is no Q flag yet, and no instruction (MRS)
+                      // to read the CPSR directly.
+                      if (rm_val > sat_val)
+                          rm_val = sat_val;
+                      else if (rm_val < 0)
+                          rm_val = 0;
+                      set_register(rd, rm_val);
+                      break;
+                  }
+                }
+            } else {
+                switch (instr->bits(22, 21)) {
+                  case 0:
+                    MOZ_CRASH();
+                    break;
+                  case 1:
+                    if (instr->bits(7,4) == 7 && instr->bits(19,16) == 15) {
+                        uint32_t rm_val = rotateBytes(get_register(instr->rmValue()),
+                                                      instr->bits(11, 10));
+                        if (instr->bit(20)) {
+                            // Sxth.
+                            set_register(rd, (int32_t)(int16_t)(rm_val & 0xFFFF));
+                        }
+                        else {
+                            // Sxtb.
+                            set_register(rd, (int32_t)(int8_t)(rm_val & 0xFF));
+                        }
+                    } else {
+                        MOZ_CRASH();
+                    }
+                    break;
+                  case 2:
+                    if ((instr->bit(20) == 0) && (instr->bits(9, 6) == 1)) {
+                        if (instr->bits(19, 16) == 0xF) {
+                            // Uxtb16.
+                            uint32_t rm_val = rotateBytes(get_register(instr->rmValue()),
+                                                          instr->bits(11, 10));
+                            set_register(rd, (rm_val & 0xFF) | (rm_val & 0xFF0000));
+                        } else {
+                            MOZ_CRASH();
+                        }
+                    } else {
+                        MOZ_CRASH();
+                    }
+                    break;
+                  case 3:
+                    if ((instr->bit(20) == 0) && (instr->bits(9, 6) == 1)) {
+                        if (instr->bits(19, 16) == 0xF) {
+                            // Uxtb.
+                            uint32_t rm_val = rotateBytes(get_register(instr->rmValue()),
+                                                          instr->bits(11, 10));
+                            set_register(rd, (rm_val & 0xFF));
+                        } else {
+                            // Uxtab.
+                            uint32_t rn_val = get_register(rn);
+                            uint32_t rm_val = rotateBytes(get_register(instr->rmValue()),
+                                                          instr->bits(11, 10));
+                            set_register(rd, rn_val + (rm_val & 0xFF));
+                        }
+                    } else if ((instr->bit(20) == 1) && (instr->bits(9, 6) == 1)) {
+                        if (instr->bits(19, 16) == 0xF) {
+                            // Uxth.
+                            uint32_t rm_val = rotateBytes(get_register(instr->rmValue()),
+                                                          instr->bits(11, 10));
+                            set_register(rd, (rm_val & 0xFFFF));
+                        } else {
+                            // Uxtah.
+                            uint32_t rn_val = get_register(rn);
+                            uint32_t rm_val = rotateBytes(get_register(instr->rmValue()),
+                                                          instr->bits(11, 10));
+                            set_register(rd, rn_val + (rm_val & 0xFFFF));
+                        }
+                    } else {
+                        MOZ_CRASH();
+                    }
+                    break;
+                }
+            }
+            return;
+        }
+        break;
+      }
+      case db_x: { // sudiv
+        if (instr->bit(22) == 0x0 && instr->bit(20) == 0x1 &&
+            instr->bits(15,12) == 0x0f && instr->bits(7, 4) == 0x1) {
+            if (!instr->hasW()) {
+                // sdiv (in V8 notation matching ARM ISA format) rn = rm/rs.
+                int rm = instr->rmValue();
+                int32_t rm_val = get_register(rm);
+                int rs = instr->rsValue();
+                int32_t rs_val = get_register(rs);
+                int32_t ret_val = 0;
+                MOZ_ASSERT(rs_val != 0);
+                if ((rm_val == INT32_MIN) && (rs_val == -1))
+                    ret_val = INT32_MIN;
+                else
+                    ret_val = rm_val / rs_val;
+                set_register(rn, ret_val);
+                return;
+            } else {
+                // udiv (in V8 notation matching ARM ISA format) rn = rm/rs.
+                int rm = instr->rmValue();
+                uint32_t rm_val = get_register(rm);
+                int rs = instr->rsValue();
+                uint32_t rs_val = get_register(rs);
+                uint32_t ret_val = 0;
+                MOZ_ASSERT(rs_val != 0);
+                ret_val = rm_val / rs_val;
+                set_register(rn, ret_val);
+                return;
+            }
+        }
+
+        addr = rn_val - shifter_operand;
+        if (instr->hasW())
+            set_register(rn, addr);
+        break;
+      }
+      case ib_x: {
+        if (instr->hasW() && (instr->bits(6, 4) == 0x5)) {
+            uint32_t widthminus1 = static_cast<uint32_t>(instr->bits(20, 16));
+            uint32_t lsbit = static_cast<uint32_t>(instr->bits(11, 7));
+            uint32_t msbit = widthminus1 + lsbit;
+            if (msbit <= 31) {
+                if (instr->bit(22)) {
+                    // ubfx - unsigned bitfield extract.
+                    uint32_t rm_val = static_cast<uint32_t>(get_register(instr->rmValue()));
+                    uint32_t extr_val = rm_val << (31 - msbit);
+                    extr_val = extr_val >> (31 - widthminus1);
+                    set_register(instr->rdValue(), extr_val);
+                } else {
+                    // sbfx - signed bitfield extract.
+                    int32_t rm_val = get_register(instr->rmValue());
+                    int32_t extr_val = rm_val << (31 - msbit);
+                    extr_val = extr_val >> (31 - widthminus1);
+                    set_register(instr->rdValue(), extr_val);
+                }
+            } else {
+                MOZ_CRASH();
+            }
+            return;
+        } else if (!instr->hasW() && (instr->bits(6, 4) == 0x1)) {
+            uint32_t lsbit = static_cast<uint32_t>(instr->bits(11, 7));
+            uint32_t msbit = static_cast<uint32_t>(instr->bits(20, 16));
+            if (msbit >= lsbit) {
+                // bfc or bfi - bitfield clear/insert.
+                uint32_t rd_val =
+                    static_cast<uint32_t>(get_register(instr->rdValue()));
+                uint32_t bitcount = msbit - lsbit + 1;
+                uint32_t mask = (1 << bitcount) - 1;
+                rd_val &= ~(mask << lsbit);
+                if (instr->rmValue() != 15) {
+                    // bfi - bitfield insert.
+                    uint32_t rm_val =
+                        static_cast<uint32_t>(get_register(instr->rmValue()));
+                    rm_val &= mask;
+                    rd_val |= rm_val << lsbit;
+                }
+                set_register(instr->rdValue(), rd_val);
+            } else {
+                MOZ_CRASH();
+            }
+            return;
+        } else {
+            addr = rn_val + shifter_operand;
+            if (instr->hasW())
+                set_register(rn, addr);
+        }
+        break;
+      }
+      default:
+        MOZ_CRASH();
+        break;
+    }
+    if (instr->hasB()) {
+        if (instr->hasL()) {
+            uint8_t byte = readB(addr);
+            set_register(rd, byte);
+        } else {
+            uint8_t byte = get_register(rd);
+            writeB(addr, byte);
+        }
+    } else {
+        if (instr->hasL())
+            set_register(rd, readW(addr, instr, AllowUnaligned));
+        else
+            writeW(addr, get_register(rd), instr, AllowUnaligned);
+    }
+}
+
+void
+Simulator::decodeType4(SimInstruction* instr)
+{
+    // Only allowed to be set in privileged mode.
+    MOZ_ASSERT(instr->bit(22) == 0);
+    bool load = instr->hasL();
+    handleRList(instr, load);
+}
+
+void
+Simulator::decodeType5(SimInstruction* instr)
+{
+    int off = instr->sImmed24Value() << 2;
+    intptr_t pc_address = get_pc();
+    if (instr->hasLink())
+        set_register(lr, pc_address + SimInstruction::kInstrSize);
+    int pc_reg = get_register(pc);
+    set_pc(pc_reg + off);
+}
+
+void
+Simulator::decodeType6(SimInstruction* instr)
+{
+    decodeType6CoprocessorIns(instr);
+}
+
+void
+Simulator::decodeType7(SimInstruction* instr)
+{
+    if (instr->bit(24) == 1)
+        softwareInterrupt(instr);
+    else if (instr->bit(4) == 1 && instr->bits(11,9) != 5)
+        decodeType7CoprocessorIns(instr);
+    else
+        decodeTypeVFP(instr);
+}
+
+void
+Simulator::decodeType7CoprocessorIns(SimInstruction* instr)
+{
+    if (instr->bit(20) == 0) {
+        // MCR, MCR2
+        if (instr->coprocessorValue() == 15) {
+            int opc1 = instr->bits(23,21);
+            int opc2 = instr->bits(7,5);
+            int CRn = instr->bits(19,16);
+            int CRm = instr->bits(3,0);
+            if (opc1 == 0 && opc2 == 4 && CRn == 7 && CRm == 10) {
+                // ARMv6 DSB instruction.  We do not use DSB.
+                MOZ_CRASH("DSB not implemented");
+            } else if (opc1 == 0 && opc2 == 5 && CRn == 7 && CRm == 10) {
+                // ARMv6 DMB instruction.
+                AtomicOperations::fenceSeqCst();
+            }
+            else if (opc1 == 0 && opc2 == 4 && CRn == 7 && CRm == 5) {
+                // ARMv6 ISB instruction.  We do not use ISB.
+                MOZ_CRASH("ISB not implemented");
+            }
+            else {
+                MOZ_CRASH();
+            }
+        } else {
+            MOZ_CRASH();
+        }
+    } else {
+        // MRC, MRC2
+        MOZ_CRASH();
+    }
+}
+
+void
+Simulator::decodeTypeVFP(SimInstruction* instr)
+{
+    MOZ_ASSERT(instr->typeValue() == 7 && instr->bit(24) == 0);
+    MOZ_ASSERT(instr->bits(11, 9) == 0x5);
+
+    // Obtain double precision register codes.
+    VFPRegPrecision precision = (instr->szValue() == 1) ? kDoublePrecision : kSinglePrecision;
+    int vm = instr->VFPMRegValue(precision);
+    int vd = instr->VFPDRegValue(precision);
+    int vn = instr->VFPNRegValue(precision);
+
+    if (instr->bit(4) == 0) {
+        if (instr->opc1Value() == 0x7) {
+            // Other data processing instructions.
+            if ((instr->opc2Value() == 0x0) && (instr->opc3Value() == 0x1)) {
+                // vmov register to register.
+                if (instr->szValue() == 0x1) {
+                    int m = instr->VFPMRegValue(kDoublePrecision);
+                    int d = instr->VFPDRegValue(kDoublePrecision);
+                    double temp;
+                    get_double_from_d_register(m, &temp);
+                    set_d_register_from_double(d, temp);
+                } else {
+                    int m = instr->VFPMRegValue(kSinglePrecision);
+                    int d = instr->VFPDRegValue(kSinglePrecision);
+                    float temp;
+                    get_float_from_s_register(m, &temp);
+                    set_s_register_from_float(d, temp);
+                }
+            } else if ((instr->opc2Value() == 0x0) && (instr->opc3Value() == 0x3)) {
+                // vabs
+                if (instr->szValue() == 0x1) {
+                    union {
+                        double f64;
+                        uint64_t u64;
+                    } u;
+                    get_double_from_d_register(vm, &u.f64);
+                    u.u64 &= 0x7fffffffffffffffu;
+                    double dd_value = u.f64;
+                    canonicalizeNaN(&dd_value);
+                    set_d_register_from_double(vd, dd_value);
+                } else {
+                    union {
+                        float f32;
+                        uint32_t u32;
+                    } u;
+                    get_float_from_s_register(vm, &u.f32);
+                    u.u32 &= 0x7fffffffu;
+                    float fd_value = u.f32;
+                    canonicalizeNaN(&fd_value);
+                    set_s_register_from_float(vd, fd_value);
+                }
+            } else if ((instr->opc2Value() == 0x1) && (instr->opc3Value() == 0x1)) {
+                // vneg
+                if (instr->szValue() == 0x1) {
+                    double dm_value;
+                    get_double_from_d_register(vm, &dm_value);
+                    double dd_value = -dm_value;
+                    canonicalizeNaN(&dd_value);
+                    set_d_register_from_double(vd, dd_value);
+                } else {
+                    float fm_value;
+                    get_float_from_s_register(vm, &fm_value);
+                    float fd_value = -fm_value;
+                    canonicalizeNaN(&fd_value);
+                    set_s_register_from_float(vd, fd_value);
+                }
+            } else if ((instr->opc2Value() == 0x7) && (instr->opc3Value() == 0x3)) {
+                decodeVCVTBetweenDoubleAndSingle(instr);
+            } else if ((instr->opc2Value() == 0x8) && (instr->opc3Value() & 0x1)) {
+                decodeVCVTBetweenFloatingPointAndInteger(instr);
+            } else if ((instr->opc2Value() == 0xA) && (instr->opc3Value() == 0x3) &&
+                       (instr->bit(8) == 1)) {
+                // vcvt.f64.s32 Dd, Dd, #<fbits>.
+                int fraction_bits = 32 - ((instr->bits(3, 0) << 1) | instr->bit(5));
+                int fixed_value = get_sinteger_from_s_register(vd * 2);
+                double divide = 1 << fraction_bits;
+                set_d_register_from_double(vd, fixed_value / divide);
+            } else if (((instr->opc2Value() >> 1) == 0x6) &&
+                       (instr->opc3Value() & 0x1)) {
+                decodeVCVTBetweenFloatingPointAndInteger(instr);
+            } else if (((instr->opc2Value() == 0x4) || (instr->opc2Value() == 0x5)) &&
+                       (instr->opc3Value() & 0x1)) {
+                decodeVCMP(instr);
+            } else if (((instr->opc2Value() == 0x1)) && (instr->opc3Value() == 0x3)) {
+                // vsqrt
+                if (instr->szValue() == 0x1) {
+                    double dm_value;
+                    get_double_from_d_register(vm, &dm_value);
+                    double dd_value = std::sqrt(dm_value);
+                    canonicalizeNaN(&dd_value);
+                    set_d_register_from_double(vd, dd_value);
+                } else {
+                    float fm_value;
+                    get_float_from_s_register(vm, &fm_value);
+                    float fd_value = std::sqrt(fm_value);
+                    canonicalizeNaN(&fd_value);
+                    set_s_register_from_float(vd, fd_value);
+                }
+            } else if (instr->opc3Value() == 0x0) {
+                // vmov immediate.
+                if (instr->szValue() == 0x1) {
+                    set_d_register_from_double(vd, instr->doubleImmedVmov());
+                } else {
+                    // vmov.f32 immediate.
+                    set_s_register_from_float(vd, instr->float32ImmedVmov());
+                }
+            } else {
+                decodeVCVTBetweenFloatingPointAndIntegerFrac(instr);
+            }
+        } else if (instr->opc1Value() == 0x3) {
+            if (instr->szValue() != 0x1) {
+                if (instr->opc3Value() & 0x1) {
+                    // vsub
+                    float fn_value;
+                    get_float_from_s_register(vn, &fn_value);
+                    float fm_value;
+                    get_float_from_s_register(vm, &fm_value);
+                    float fd_value = fn_value - fm_value;
+                    canonicalizeNaN(&fd_value);
+                    set_s_register_from_float(vd, fd_value);
+                } else {
+                    // vadd
+                    float fn_value;
+                    get_float_from_s_register(vn, &fn_value);
+                    float fm_value;
+                    get_float_from_s_register(vm, &fm_value);
+                    float fd_value = fn_value + fm_value;
+                    canonicalizeNaN(&fd_value);
+                    set_s_register_from_float(vd, fd_value);
+                }
+            } else {
+                if (instr->opc3Value() & 0x1) {
+                    // vsub
+                    double dn_value;
+                    get_double_from_d_register(vn, &dn_value);
+                    double dm_value;
+                    get_double_from_d_register(vm, &dm_value);
+                    double dd_value = dn_value - dm_value;
+                    canonicalizeNaN(&dd_value);
+                    set_d_register_from_double(vd, dd_value);
+                } else {
+                    // vadd
+                    double dn_value;
+                    get_double_from_d_register(vn, &dn_value);
+                    double dm_value;
+                    get_double_from_d_register(vm, &dm_value);
+                    double dd_value = dn_value + dm_value;
+                    canonicalizeNaN(&dd_value);
+                    set_d_register_from_double(vd, dd_value);
+                }
+            }
+        } else if ((instr->opc1Value() == 0x2) && !(instr->opc3Value() & 0x1)) {
+            // vmul
+            if (instr->szValue() != 0x1) {
+                float fn_value;
+                get_float_from_s_register(vn, &fn_value);
+                float fm_value;
+                get_float_from_s_register(vm, &fm_value);
+                float fd_value = fn_value * fm_value;
+                canonicalizeNaN(&fd_value);
+                set_s_register_from_float(vd, fd_value);
+            } else {
+                double dn_value;
+                get_double_from_d_register(vn, &dn_value);
+                double dm_value;
+                get_double_from_d_register(vm, &dm_value);
+                double dd_value = dn_value * dm_value;
+                canonicalizeNaN(&dd_value);
+                set_d_register_from_double(vd, dd_value);
+            }
+        } else if ((instr->opc1Value() == 0x0)) {
+            // vmla, vmls
+            const bool is_vmls = (instr->opc3Value() & 0x1);
+
+            if (instr->szValue() != 0x1)
+                MOZ_CRASH("Not used by V8.");
+
+            double dd_val;
+            get_double_from_d_register(vd, &dd_val);
+            double dn_val;
+            get_double_from_d_register(vn, &dn_val);
+            double dm_val;
+            get_double_from_d_register(vm, &dm_val);
+
+            // Note: we do the mul and add/sub in separate steps to avoid
+            // getting a result with too high precision.
+            set_d_register_from_double(vd, dn_val * dm_val);
+            double temp;
+            get_double_from_d_register(vd, &temp);
+            if (is_vmls)
+                temp = dd_val - temp;
+            else
+                temp = dd_val + temp;
+            canonicalizeNaN(&temp);
+            set_d_register_from_double(vd, temp);
+        } else if ((instr->opc1Value() == 0x4) && !(instr->opc3Value() & 0x1)) {
+            // vdiv
+            if (instr->szValue() != 0x1) {
+                float fn_value;
+                get_float_from_s_register(vn, &fn_value);
+                float fm_value;
+                get_float_from_s_register(vm, &fm_value);
+                float fd_value = fn_value / fm_value;
+                div_zero_vfp_flag_ = (fm_value == 0);
+                canonicalizeNaN(&fd_value);
+                set_s_register_from_float(vd, fd_value);
+            } else {
+                double dn_value;
+                get_double_from_d_register(vn, &dn_value);
+                double dm_value;
+                get_double_from_d_register(vm, &dm_value);
+                double dd_value = dn_value / dm_value;
+                div_zero_vfp_flag_ = (dm_value == 0);
+                canonicalizeNaN(&dd_value);
+                set_d_register_from_double(vd, dd_value);
+            }
+        } else {
+            MOZ_CRASH();
+        }
+    } else {
+        if (instr->VCValue() == 0x0 && instr->VAValue() == 0x0) {
+            decodeVMOVBetweenCoreAndSinglePrecisionRegisters(instr);
+        } else if ((instr->VLValue() == 0x0) &&
+                   (instr->VCValue() == 0x1) &&
+                   (instr->bit(23) == 0x0)) {
+            // vmov (ARM core register to scalar).
+            int vd = instr->bits(19, 16) | (instr->bit(7) << 4);
+            double dd_value;
+            get_double_from_d_register(vd, &dd_value);
+            int32_t data[2];
+            memcpy(data, &dd_value, 8);
+            data[instr->bit(21)] = get_register(instr->rtValue());
+            memcpy(&dd_value, data, 8);
+            set_d_register_from_double(vd, dd_value);
+        } else if ((instr->VLValue() == 0x1) &&
+                   (instr->VCValue() == 0x1) &&
+                   (instr->bit(23) == 0x0)) {
+            // vmov (scalar to ARM core register).
+            int vn = instr->bits(19, 16) | (instr->bit(7) << 4);
+            double dn_value;
+            get_double_from_d_register(vn, &dn_value);
+            int32_t data[2];
+            memcpy(data, &dn_value, 8);
+            set_register(instr->rtValue(), data[instr->bit(21)]);
+        } else if ((instr->VLValue() == 0x1) &&
+                   (instr->VCValue() == 0x0) &&
+                   (instr->VAValue() == 0x7) &&
+                   (instr->bits(19, 16) == 0x1)) {
+            // vmrs
+            uint32_t rt = instr->rtValue();
+            if (rt == 0xF) {
+                copy_FPSCR_to_APSR();
+            } else {
+                // Emulate FPSCR from the Simulator flags.
+                uint32_t fpscr = (n_flag_FPSCR_ << 31) |
+                    (z_flag_FPSCR_ << 30) |
+                    (c_flag_FPSCR_ << 29) |
+                    (v_flag_FPSCR_ << 28) |
+                    (FPSCR_default_NaN_mode_ << 25) |
+                    (inexact_vfp_flag_ << 4) |
+                    (underflow_vfp_flag_ << 3) |
+                    (overflow_vfp_flag_ << 2) |
+                    (div_zero_vfp_flag_ << 1) |
+                    (inv_op_vfp_flag_ << 0) |
+                    (FPSCR_rounding_mode_);
+                set_register(rt, fpscr);
+            }
+        } else if ((instr->VLValue() == 0x0) &&
+                   (instr->VCValue() == 0x0) &&
+                   (instr->VAValue() == 0x7) &&
+                   (instr->bits(19, 16) == 0x1)) {
+            // vmsr
+            uint32_t rt = instr->rtValue();
+            if (rt == pc) {
+                MOZ_CRASH();
+            } else {
+                uint32_t rt_value = get_register(rt);
+                n_flag_FPSCR_ = (rt_value >> 31) & 1;
+                z_flag_FPSCR_ = (rt_value >> 30) & 1;
+                c_flag_FPSCR_ = (rt_value >> 29) & 1;
+                v_flag_FPSCR_ = (rt_value >> 28) & 1;
+                FPSCR_default_NaN_mode_ = (rt_value >> 25) & 1;
+                inexact_vfp_flag_ = (rt_value >> 4) & 1;
+                underflow_vfp_flag_ = (rt_value >> 3) & 1;
+                overflow_vfp_flag_ = (rt_value >> 2) & 1;
+                div_zero_vfp_flag_ = (rt_value >> 1) & 1;
+                inv_op_vfp_flag_ = (rt_value >> 0) & 1;
+                FPSCR_rounding_mode_ =
+                    static_cast<VFPRoundingMode>((rt_value) & kVFPRoundingModeMask);
+            }
+        } else {
+            MOZ_CRASH();
+        }
+    }
+}
+
+void
+Simulator::decodeVMOVBetweenCoreAndSinglePrecisionRegisters(SimInstruction* instr)
+{
+    MOZ_ASSERT(instr->bit(4) == 1 &&
+               instr->VCValue() == 0x0 &&
+               instr->VAValue() == 0x0);
+
+    int t = instr->rtValue();
+    int n = instr->VFPNRegValue(kSinglePrecision);
+    bool to_arm_register = (instr->VLValue() == 0x1);
+    if (to_arm_register) {
+        int32_t int_value = get_sinteger_from_s_register(n);
+        set_register(t, int_value);
+    } else {
+        int32_t rs_val = get_register(t);
+        set_s_register_from_sinteger(n, rs_val);
+    }
+}
+
+void
+Simulator::decodeVCMP(SimInstruction* instr)
+{
+    MOZ_ASSERT((instr->bit(4) == 0) && (instr->opc1Value() == 0x7));
+    MOZ_ASSERT(((instr->opc2Value() == 0x4) || (instr->opc2Value() == 0x5)) &&
+               (instr->opc3Value() & 0x1));
+    // Comparison.
+
+    VFPRegPrecision precision = kSinglePrecision;
+    if (instr->szValue() == 1)
+        precision = kDoublePrecision;
+
+    int d = instr->VFPDRegValue(precision);
+    int m = 0;
+    if (instr->opc2Value() == 0x4)
+        m = instr->VFPMRegValue(precision);
+
+    if (precision == kDoublePrecision) {
+        double dd_value;
+        get_double_from_d_register(d, &dd_value);
+        double dm_value = 0.0;
+        if (instr->opc2Value() == 0x4)
+            get_double_from_d_register(m, &dm_value);
+
+        // Raise exceptions for quiet NaNs if necessary.
+        if (instr->bit(7) == 1) {
+            if (mozilla::IsNaN(dd_value))
+                inv_op_vfp_flag_ = true;
+        }
+        compute_FPSCR_Flags(dd_value, dm_value);
+    } else {
+        float fd_value;
+        get_float_from_s_register(d, &fd_value);
+        float fm_value = 0.0;
+        if (instr->opc2Value() == 0x4)
+            get_float_from_s_register(m, &fm_value);
+
+        // Raise exceptions for quiet NaNs if necessary.
+        if (instr->bit(7) == 1) {
+            if (mozilla::IsNaN(fd_value))
+                inv_op_vfp_flag_ = true;
+        }
+        compute_FPSCR_Flags(fd_value, fm_value);
+    }
+}
+
+void
+Simulator::decodeVCVTBetweenDoubleAndSingle(SimInstruction* instr)
+{
+    MOZ_ASSERT(instr->bit(4) == 0 && instr->opc1Value() == 0x7);
+    MOZ_ASSERT(instr->opc2Value() == 0x7 && instr->opc3Value() == 0x3);
+
+    VFPRegPrecision dst_precision = kDoublePrecision;
+    VFPRegPrecision src_precision = kSinglePrecision;
+    if (instr->szValue() == 1) {
+        dst_precision = kSinglePrecision;
+        src_precision = kDoublePrecision;
+    }
+
+    int dst = instr->VFPDRegValue(dst_precision);
+    int src = instr->VFPMRegValue(src_precision);
+
+    if (dst_precision == kSinglePrecision) {
+        double val;
+        get_double_from_d_register(src, &val);
+        set_s_register_from_float(dst, static_cast<float>(val));
+    } else {
+        float val;
+        get_float_from_s_register(src, &val);
+        set_d_register_from_double(dst, static_cast<double>(val));
+    }
+}
+
+static bool
+get_inv_op_vfp_flag(VFPRoundingMode mode, double val, bool unsigned_)
+{
+    MOZ_ASSERT(mode == SimRN || mode == SimRM || mode == SimRZ);
+    double max_uint = static_cast<double>(0xffffffffu);
+    double max_int = static_cast<double>(INT32_MAX);
+    double min_int = static_cast<double>(INT32_MIN);
+
+    // Check for NaN.
+    if (val != val)
+        return true;
+
+    // Check for overflow. This code works because 32bit integers can be exactly
+    // represented by ieee-754 64bit floating-point values.
+    switch (mode) {
+      case SimRN:
+        return  unsigned_ ? (val >= (max_uint + 0.5)) ||
+                            (val < -0.5)
+                          : (val >= (max_int + 0.5)) ||
+                            (val < (min_int - 0.5));
+      case SimRM:
+        return  unsigned_ ? (val >= (max_uint + 1.0)) ||
+                            (val < 0)
+                          : (val >= (max_int + 1.0)) ||
+                            (val < min_int);
+      case SimRZ:
+        return  unsigned_ ? (val >= (max_uint + 1.0)) ||
+                            (val <= -1)
+                          : (val >= (max_int + 1.0)) ||
+                            (val <= (min_int - 1.0));
+      default:
+        MOZ_CRASH();
+        return true;
+    }
+}
+
+// We call this function only if we had a vfp invalid exception.
+// It returns the correct saturated value.
+static int
+VFPConversionSaturate(double val, bool unsigned_res)
+{
+    if (val != val) // NaN.
+        return 0;
+    if (unsigned_res)
+        return (val < 0) ? 0 : 0xffffffffu;
+    return (val < 0) ? INT32_MIN : INT32_MAX;
+}
+
+void
+Simulator::decodeVCVTBetweenFloatingPointAndInteger(SimInstruction* instr)
+{
+    MOZ_ASSERT((instr->bit(4) == 0) && (instr->opc1Value() == 0x7) &&
+               (instr->bits(27, 23) == 0x1D));
+    MOZ_ASSERT(((instr->opc2Value() == 0x8) && (instr->opc3Value() & 0x1)) ||
+               (((instr->opc2Value() >> 1) == 0x6) && (instr->opc3Value() & 0x1)));
+
+    // Conversion between floating-point and integer.
+    bool to_integer = (instr->bit(18) == 1);
+
+    VFPRegPrecision src_precision = (instr->szValue() == 1) ? kDoublePrecision : kSinglePrecision;
+
+    if (to_integer) {
+        // We are playing with code close to the C++ standard's limits below,
+        // hence the very simple code and heavy checks.
+        //
+        // Note: C++ defines default type casting from floating point to integer
+        // as (close to) rounding toward zero ("fractional part discarded").
+
+        int dst = instr->VFPDRegValue(kSinglePrecision);
+        int src = instr->VFPMRegValue(src_precision);
+
+        // Bit 7 in vcvt instructions indicates if we should use the FPSCR
+        // rounding mode or the default Round to Zero mode.
+        VFPRoundingMode mode = (instr->bit(7) != 1) ? FPSCR_rounding_mode_ : SimRZ;
+        MOZ_ASSERT(mode == SimRM || mode == SimRZ || mode == SimRN);
+
+        bool unsigned_integer = (instr->bit(16) == 0);
+        bool double_precision = (src_precision == kDoublePrecision);
+
+        double val;
+        if (double_precision) {
+            get_double_from_d_register(src, &val);
+        } else {
+            float fval;
+            get_float_from_s_register(src, &fval);
+            val = double(fval);
+        }
+
+        int temp = unsigned_integer ? static_cast<uint32_t>(val) : static_cast<int32_t>(val);
+
+        inv_op_vfp_flag_ = get_inv_op_vfp_flag(mode, val, unsigned_integer);
+
+        double abs_diff = unsigned_integer
+                          ? std::fabs(val - static_cast<uint32_t>(temp))
+                          : std::fabs(val - temp);
+
+        inexact_vfp_flag_ = (abs_diff != 0);
+
+        if (inv_op_vfp_flag_) {
+            temp = VFPConversionSaturate(val, unsigned_integer);
+        } else {
+            switch (mode) {
+              case SimRN: {
+                int val_sign = (val > 0) ? 1 : -1;
+                if (abs_diff > 0.5) {
+                    temp += val_sign;
+                } else if (abs_diff == 0.5) {
+                    // Round to even if exactly halfway.
+                    temp = ((temp % 2) == 0) ? temp : temp + val_sign;
+                }
+                break;
+              }
+
+              case SimRM:
+                temp = temp > val ? temp - 1 : temp;
+                  break;
+
+              case SimRZ:
+                // Nothing to do.
+                break;
+
+              default:
+                MOZ_CRASH();
+            }
+        }
+
+        // Update the destination register.
+        set_s_register_from_sinteger(dst, temp);
+    } else {
+        bool unsigned_integer = (instr->bit(7) == 0);
+        int dst = instr->VFPDRegValue(src_precision);
+        int src = instr->VFPMRegValue(kSinglePrecision);
+
+        int val = get_sinteger_from_s_register(src);
+
+        if (src_precision == kDoublePrecision) {
+            if (unsigned_integer)
+                set_d_register_from_double(dst, static_cast<double>(static_cast<uint32_t>(val)));
+            else
+                set_d_register_from_double(dst, static_cast<double>(val));
+        } else {
+            if (unsigned_integer)
+                set_s_register_from_float(dst, static_cast<float>(static_cast<uint32_t>(val)));
+            else
+                set_s_register_from_float(dst, static_cast<float>(val));
+        }
+    }
+}
+
+// A VFPv3 specific instruction.
+void
+Simulator::decodeVCVTBetweenFloatingPointAndIntegerFrac(SimInstruction* instr)
+{
+    MOZ_ASSERT(instr->bits(27, 24) == 0xE && instr->opc1Value() == 0x7 && instr->bit(19) == 1 &&
+               instr->bit(17) == 1 && instr->bits(11,9) == 0x5 && instr->bit(6) == 1 &&
+               instr->bit(4) == 0);
+
+    int size = (instr->bit(7) == 1) ? 32 : 16;
+
+    int fraction_bits = size - ((instr->bits(3, 0) << 1) | instr->bit(5));
+    double mult = 1 << fraction_bits;
+
+    MOZ_ASSERT(size == 32); // Only handling size == 32 for now.
+
+    // Conversion between floating-point and integer.
+    bool to_fixed = (instr->bit(18) == 1);
+
+    VFPRegPrecision precision = (instr->szValue() == 1) ? kDoublePrecision : kSinglePrecision;
+
+    if (to_fixed) {
+        // We are playing with code close to the C++ standard's limits below,
+        // hence the very simple code and heavy checks.
+        //
+        // Note: C++ defines default type casting from floating point to integer
+        // as (close to) rounding toward zero ("fractional part discarded").
+
+        int dst = instr->VFPDRegValue(precision);
+
+        bool unsigned_integer = (instr->bit(16) == 1);
+        bool double_precision = (precision == kDoublePrecision);
+
+        double val;
+        if (double_precision) {
+            get_double_from_d_register(dst, &val);
+        } else {
+            float fval;
+            get_float_from_s_register(dst, &fval);
+            val = double(fval);
+        }
+
+        // Scale value by specified number of fraction bits.
+        val *= mult;
+
+        // Rounding down towards zero. No need to account for the rounding error
+        // as this instruction always rounds down towards zero. See SimRZ below.
+        int temp = unsigned_integer ? static_cast<uint32_t>(val) : static_cast<int32_t>(val);
+
+        inv_op_vfp_flag_ = get_inv_op_vfp_flag(SimRZ, val, unsigned_integer);
+
+        double abs_diff = unsigned_integer
+                          ? std::fabs(val - static_cast<uint32_t>(temp))
+                          : std::fabs(val - temp);
+
+        inexact_vfp_flag_ = (abs_diff != 0);
+
+        if (inv_op_vfp_flag_)
+            temp = VFPConversionSaturate(val, unsigned_integer);
+
+        // Update the destination register.
+        if (double_precision) {
+            uint32_t dbl[2];
+            dbl[0] = temp; dbl[1] = 0;
+            set_d_register(dst, dbl);
+        } else {
+            set_s_register_from_sinteger(dst, temp);
+        }
+    } else {
+        MOZ_CRASH();  // Not implemented, fixed to float.
+    }
+}
+
+void
+Simulator::decodeType6CoprocessorIns(SimInstruction* instr)
+{
+    MOZ_ASSERT(instr->typeValue() == 6);
+
+    if (instr->coprocessorValue() == 0xA) {
+        switch (instr->opcodeValue()) {
+          case 0x8:
+          case 0xA:
+          case 0xC:
+          case 0xE: {  // Load and store single precision float to memory.
+            int rn = instr->rnValue();
+            int vd = instr->VFPDRegValue(kSinglePrecision);
+            int offset = instr->immed8Value();
+            if (!instr->hasU())
+                offset = -offset;
+
+            int32_t address = get_register(rn) + 4 * offset;
+            if (instr->hasL()) {
+                // Load double from memory: vldr.
+                set_s_register_from_sinteger(vd, readW(address, instr));
+            } else {
+                // Store double to memory: vstr.
+                writeW(address, get_sinteger_from_s_register(vd), instr);
+            }
+            break;
+          }
+          case 0x4:
+          case 0x5:
+          case 0x6:
+          case 0x7:
+          case 0x9:
+          case 0xB:
+            // Load/store multiple single from memory: vldm/vstm.
+            handleVList(instr);
+            break;
+          default:
+            MOZ_CRASH();
+        }
+    } else if (instr->coprocessorValue() == 0xB) {
+        switch (instr->opcodeValue()) {
+          case 0x2:
+            // Load and store double to two GP registers
+            if (instr->bits(7, 6) != 0 || instr->bit(4) != 1) {
+                MOZ_CRASH();  // Not used atm.
+            } else {
+                int rt = instr->rtValue();
+                int rn = instr->rnValue();
+                int vm = instr->VFPMRegValue(kDoublePrecision);
+                if (instr->hasL()) {
+                    int32_t data[2];
+                    double d;
+                    get_double_from_d_register(vm, &d);
+                    memcpy(data, &d, 8);
+                    set_register(rt, data[0]);
+                    set_register(rn, data[1]);
+                } else {
+                    int32_t data[] = { get_register(rt), get_register(rn) };
+                    double d;
+                    memcpy(&d, data, 8);
+                    set_d_register_from_double(vm, d);
+                }
+            }
+            break;
+          case 0x8:
+          case 0xA:
+          case 0xC:
+          case 0xE: {  // Load and store double to memory.
+            int rn = instr->rnValue();
+            int vd = instr->VFPDRegValue(kDoublePrecision);
+            int offset = instr->immed8Value();
+            if (!instr->hasU())
+                offset = -offset;
+            int32_t address = get_register(rn) + 4 * offset;
+            if (instr->hasL()) {
+                // Load double from memory: vldr.
+                uint64_t data = readQ(address, instr);
+                double val;
+                memcpy(&val, &data, 8);
+                set_d_register_from_double(vd, val);
+            } else {
+                // Store double to memory: vstr.
+                uint64_t data;
+                double val;
+                get_double_from_d_register(vd, &val);
+                memcpy(&data, &val, 8);
+                writeQ(address, data, instr);
+            }
+            break;
+          }
+          case 0x4:
+          case 0x5:
+          case 0x6:
+          case 0x7:
+          case 0x9:
+          case 0xB:
+            // Load/store multiple double from memory: vldm/vstm.
+            handleVList(instr);
+            break;
+          default:
+            MOZ_CRASH();
+        }
+    } else {
+        MOZ_CRASH();
+    }
+}
+
+void
+Simulator::decodeSpecialCondition(SimInstruction* instr)
+{
+    switch (instr->specialValue()) {
+      case 5:
+        if (instr->bits(18, 16) == 0 && instr->bits(11, 6) == 0x28 && instr->bit(4) == 1) {
+            // vmovl signed
+            if ((instr->vdValue() & 1) != 0)
+                MOZ_CRASH("Undefined behavior");
+            int Vd = (instr->bit(22) << 3) | (instr->vdValue() >> 1);
+            int Vm = (instr->bit(5) << 4) | instr->vmValue();
+            int imm3 = instr->bits(21, 19);
+            if (imm3 != 1 && imm3 != 2 && imm3 != 4)
+                MOZ_CRASH();
+            int esize = 8 * imm3;
+            int elements = 64 / esize;
+            int8_t from[8];
+            get_d_register(Vm, reinterpret_cast<uint64_t*>(from));
+            int16_t to[8];
+            int e = 0;
+            while (e < elements) {
+                to[e] = from[e];
+                e++;
+            }
+            set_q_register(Vd, reinterpret_cast<uint64_t*>(to));
+        } else {
+            MOZ_CRASH();
+        }
+        break;
+      case 7:
+        if (instr->bits(18, 16) == 0 && instr->bits(11, 6) == 0x28 && instr->bit(4) == 1) {
+            // vmovl unsigned.
+            if ((instr->vdValue() & 1) != 0)
+                MOZ_CRASH("Undefined behavior");
+            int Vd = (instr->bit(22) << 3) | (instr->vdValue() >> 1);
+            int Vm = (instr->bit(5) << 4) | instr->vmValue();
+            int imm3 = instr->bits(21, 19);
+            if (imm3 != 1 && imm3 != 2 && imm3 != 4)
+                MOZ_CRASH();
+            int esize = 8 * imm3;
+            int elements = 64 / esize;
+            uint8_t from[8];
+            get_d_register(Vm, reinterpret_cast<uint64_t*>(from));
+            uint16_t to[8];
+            int e = 0;
+            while (e < elements) {
+                to[e] = from[e];
+                e++;
+            }
+            set_q_register(Vd, reinterpret_cast<uint64_t*>(to));
+        } else {
+            MOZ_CRASH();
+        }
+        break;
+      case 8:
+        if (instr->bits(21, 20) == 0) {
+            // vst1
+            int Vd = (instr->bit(22) << 4) | instr->vdValue();
+            int Rn = instr->vnValue();
+            int type = instr->bits(11, 8);
+            int Rm = instr->vmValue();
+            int32_t address = get_register(Rn);
+            int regs = 0;
+            switch (type) {
+              case nlt_1:
+                regs = 1;
+                break;
+              case nlt_2:
+                regs = 2;
+                break;
+              case nlt_3:
+                regs = 3;
+                break;
+              case nlt_4:
+                regs = 4;
+                break;
+              default:
+                MOZ_CRASH();
+                break;
+            }
+            int r = 0;
+            while (r < regs) {
+                uint32_t data[2];
+                get_d_register(Vd + r, data);
+                // TODO: We should AllowUnaligned here only if the alignment attribute of
+                // the instruction calls for default alignment.
+                writeW(address, data[0], instr, AllowUnaligned);
+                writeW(address + 4, data[1], instr, AllowUnaligned);
+                address += 8;
+                r++;
+            }
+            if (Rm != 15) {
+                if (Rm == 13)
+                    set_register(Rn, address);
+                else
+                    set_register(Rn, get_register(Rn) + get_register(Rm));
+            }
+        } else if (instr->bits(21, 20) == 2) {
+            // vld1
+            int Vd = (instr->bit(22) << 4) | instr->vdValue();
+            int Rn = instr->vnValue();
+            int type = instr->bits(11, 8);
+            int Rm = instr->vmValue();
+            int32_t address = get_register(Rn);
+            int regs = 0;
+            switch (type) {
+              case nlt_1:
+                regs = 1;
+                break;
+              case nlt_2:
+                regs = 2;
+                break;
+              case nlt_3:
+                regs = 3;
+                break;
+              case nlt_4:
+                regs = 4;
+                break;
+              default:
+                MOZ_CRASH();
+                break;
+            }
+            int r = 0;
+            while (r < regs) {
+                uint32_t data[2];
+                // TODO: We should AllowUnaligned here only if the alignment attribute of
+                // the instruction calls for default alignment.
+                data[0] = readW(address, instr, AllowUnaligned);
+                data[1] = readW(address + 4, instr, AllowUnaligned);
+                set_d_register(Vd + r, data);
+                address += 8;
+                r++;
+            }
+            if (Rm != 15) {
+                if (Rm == 13)
+                    set_register(Rn, address);
+                else
+                    set_register(Rn, get_register(Rn) + get_register(Rm));
+            }
+        } else {
+            MOZ_CRASH();
+        }
+        break;
+      case 0xA:
+        if (instr->bits(31,20) == 0xf57) {
+            switch (instr->bits(7,4)) {
+              case 5: // DMB
+                AtomicOperations::fenceSeqCst();
+                break;
+              case 4: // DSB
+                // We do not use DSB.
+                MOZ_CRASH("DSB unimplemented");
+              case 6: // ISB
+                // We do not use ISB.
+                MOZ_CRASH("ISB unimplemented");
+              default:
+                MOZ_CRASH();
+            }
+        } else {
+            MOZ_CRASH();
+        }
+        break;
+      case 0xB:
+        if (instr->bits(22, 20) == 5 && instr->bits(15, 12) == 0xf) {
+            // pld: ignore instruction.
+        } else {
+            MOZ_CRASH();
+        }
+        break;
+      case 0x1C:
+      case 0x1D:
+        if (instr->bit(4) == 1 && instr->bits(11,9) != 5) {
+            // MCR, MCR2, MRC, MRC2 with cond == 15
+            decodeType7CoprocessorIns(instr);
+        } else {
+            MOZ_CRASH();
+        }
+        break;
+      default:
+        MOZ_CRASH();
+    }
+}
+
+// Executes the current instruction.
+void
+Simulator::instructionDecode(SimInstruction* instr)
+{
+    if (Simulator::ICacheCheckingEnabled) {
+        AutoLockSimulatorCache als(this);
+        CheckICacheLocked(icache(), instr);
+    }
+
+    pc_modified_ = false;
+
+    static const uint32_t kSpecialCondition = 15 << 28;
+    if (instr->conditionField() == kSpecialCondition) {
+        decodeSpecialCondition(instr);
+    } else if (conditionallyExecute(instr)) {
+        switch (instr->typeValue()) {
+          case 0:
+          case 1:
+            decodeType01(instr);
+            break;
+          case 2:
+            decodeType2(instr);
+            break;
+          case 3:
+            decodeType3(instr);
+            break;
+          case 4:
+            decodeType4(instr);
+            break;
+          case 5:
+            decodeType5(instr);
+            break;
+          case 6:
+            decodeType6(instr);
+            break;
+          case 7:
+            decodeType7(instr);
+            break;
+          default:
+            MOZ_CRASH();
+            break;
+        }
+        // If the instruction is a non taken conditional stop, we need to skip
+        // the inlined message address.
+    } else if (instr->isStop()) {
+        set_pc(get_pc() + 2 * SimInstruction::kInstrSize);
+    }
+    if (!pc_modified_)
+        set_register(pc, reinterpret_cast<int32_t>(instr) + SimInstruction::kInstrSize);
+}
+
+void
+Simulator::enable_single_stepping(SingleStepCallback cb, void* arg)
+{
+    single_stepping_ = true;
+    single_step_callback_ = cb;
+    single_step_callback_arg_ = arg;
+    single_step_callback_(single_step_callback_arg_, this, (void*)get_pc());
+}
+
+void
+Simulator::disable_single_stepping()
+{
+    if (!single_stepping_)
+        return;
+    single_step_callback_(single_step_callback_arg_, this, (void*)get_pc());
+    single_stepping_ = false;
+    single_step_callback_ = nullptr;
+    single_step_callback_arg_ = nullptr;
+}
+
+template<bool EnableStopSimAt>
+void
+Simulator::execute()
+{
+    if (single_stepping_)
+        single_step_callback_(single_step_callback_arg_, this, nullptr);
+
+    // Get the PC to simulate. Cannot use the accessor here as we need the raw
+    // PC value and not the one used as input to arithmetic instructions.
+    int program_counter = get_pc();
+
+    while (program_counter != end_sim_pc) {
+        if (EnableStopSimAt && (icount_ == Simulator::StopSimAt)) {
+            fprintf(stderr, "\nStopped simulation at icount %lld\n", icount_);
+            ArmDebugger dbg(this);
+            dbg.debug();
+        } else {
+            if (single_stepping_)
+                single_step_callback_(single_step_callback_arg_, this, (void*)program_counter);
+            SimInstruction* instr = reinterpret_cast<SimInstruction*>(program_counter);
+            instructionDecode(instr);
+            icount_++;
+
+            int32_t rpc = resume_pc_;
+            if (MOZ_UNLIKELY(rpc != 0)) {
+                // wasm signal handler ran and we have to adjust the pc.
+                JSRuntime::innermostWasmActivation()->setResumePC((void*)get_pc());
+                set_pc(rpc);
+                resume_pc_ = 0;
+            }
+        }
+        program_counter = get_pc();
+    }
+
+    if (single_stepping_)
+        single_step_callback_(single_step_callback_arg_, this, nullptr);
+}
+
+void
+Simulator::callInternal(uint8_t* entry)
+{
+    // Prepare to execute the code at entry.
+    set_register(pc, reinterpret_cast<int32_t>(entry));
+
+    // Put down marker for end of simulation. The simulator will stop simulation
+    // when the PC reaches this value. By saving the "end simulation" value into
+    // the LR the simulation stops when returning to this call point.
+    set_register(lr, end_sim_pc);
+
+    // Remember the values of callee-saved registers. The code below assumes
+    // that r9 is not used as sb (static base) in simulator code and therefore
+    // is regarded as a callee-saved register.
+    int32_t r4_val = get_register(r4);
+    int32_t r5_val = get_register(r5);
+    int32_t r6_val = get_register(r6);
+    int32_t r7_val = get_register(r7);
+    int32_t r8_val = get_register(r8);
+    int32_t r9_val = get_register(r9);
+    int32_t r10_val = get_register(r10);
+    int32_t r11_val = get_register(r11);
+
+    // Remember d8 to d15 which are callee-saved.
+    uint64_t d8_val;
+    get_d_register(d8, &d8_val);
+    uint64_t d9_val;
+    get_d_register(d9, &d9_val);
+    uint64_t d10_val;
+    get_d_register(d10, &d10_val);
+    uint64_t d11_val;
+    get_d_register(d11, &d11_val);
+    uint64_t d12_val;
+    get_d_register(d12, &d12_val);
+    uint64_t d13_val;
+    get_d_register(d13, &d13_val);
+    uint64_t d14_val;
+    get_d_register(d14, &d14_val);
+    uint64_t d15_val;
+    get_d_register(d15, &d15_val);
+
+    // Set up the callee-saved registers with a known value. To be able to check
+    // that they are preserved properly across JS execution.
+    int32_t callee_saved_value = uint32_t(icount_);
+    uint64_t callee_saved_value_d = uint64_t(icount_);
+
+    if (!skipCalleeSavedRegsCheck) {
+        set_register(r4, callee_saved_value);
+        set_register(r5, callee_saved_value);
+        set_register(r6, callee_saved_value);
+        set_register(r7, callee_saved_value);
+        set_register(r8, callee_saved_value);
+        set_register(r9, callee_saved_value);
+        set_register(r10, callee_saved_value);
+        set_register(r11, callee_saved_value);
+
+        set_d_register(d8, &callee_saved_value_d);
+        set_d_register(d9, &callee_saved_value_d);
+        set_d_register(d10, &callee_saved_value_d);
+        set_d_register(d11, &callee_saved_value_d);
+        set_d_register(d12, &callee_saved_value_d);
+        set_d_register(d13, &callee_saved_value_d);
+        set_d_register(d14, &callee_saved_value_d);
+        set_d_register(d15, &callee_saved_value_d);
+
+    }
+    // Start the simulation.
+    if (Simulator::StopSimAt != -1L)
+        execute<true>();
+    else
+        execute<false>();
+
+    if (!skipCalleeSavedRegsCheck) {
+        // Check that the callee-saved registers have been preserved.
+        MOZ_ASSERT(callee_saved_value == get_register(r4));
+        MOZ_ASSERT(callee_saved_value == get_register(r5));
+        MOZ_ASSERT(callee_saved_value == get_register(r6));
+        MOZ_ASSERT(callee_saved_value == get_register(r7));
+        MOZ_ASSERT(callee_saved_value == get_register(r8));
+        MOZ_ASSERT(callee_saved_value == get_register(r9));
+        MOZ_ASSERT(callee_saved_value == get_register(r10));
+        MOZ_ASSERT(callee_saved_value == get_register(r11));
+
+        uint64_t value;
+        get_d_register(d8, &value);
+        MOZ_ASSERT(callee_saved_value_d == value);
+        get_d_register(d9, &value);
+        MOZ_ASSERT(callee_saved_value_d == value);
+        get_d_register(d10, &value);
+        MOZ_ASSERT(callee_saved_value_d == value);
+        get_d_register(d11, &value);
+        MOZ_ASSERT(callee_saved_value_d == value);
+        get_d_register(d12, &value);
+        MOZ_ASSERT(callee_saved_value_d == value);
+        get_d_register(d13, &value);
+        MOZ_ASSERT(callee_saved_value_d == value);
+        get_d_register(d14, &value);
+        MOZ_ASSERT(callee_saved_value_d == value);
+        get_d_register(d15, &value);
+        MOZ_ASSERT(callee_saved_value_d == value);
+
+        // Restore callee-saved registers with the original value.
+        set_register(r4, r4_val);
+        set_register(r5, r5_val);
+        set_register(r6, r6_val);
+        set_register(r7, r7_val);
+        set_register(r8, r8_val);
+        set_register(r9, r9_val);
+        set_register(r10, r10_val);
+        set_register(r11, r11_val);
+
+        set_d_register(d8, &d8_val);
+        set_d_register(d9, &d9_val);
+        set_d_register(d10, &d10_val);
+        set_d_register(d11, &d11_val);
+        set_d_register(d12, &d12_val);
+        set_d_register(d13, &d13_val);
+        set_d_register(d14, &d14_val);
+        set_d_register(d15, &d15_val);
+    }
+}
+
+int32_t
+Simulator::call(uint8_t* entry, int argument_count, ...)
+{
+    va_list parameters;
+    va_start(parameters, argument_count);
+
+    // First four arguments passed in registers.
+    MOZ_ASSERT(argument_count >= 1);
+    set_register(r0, va_arg(parameters, int32_t));
+    if (argument_count >= 2)
+        set_register(r1, va_arg(parameters, int32_t));
+    if (argument_count >= 3)
+        set_register(r2, va_arg(parameters, int32_t));
+    if (argument_count >= 4)
+        set_register(r3, va_arg(parameters, int32_t));
+
+    // Remaining arguments passed on stack.
+    int original_stack = get_register(sp);
+    int entry_stack = original_stack;
+    if (argument_count >= 4)
+        entry_stack -= (argument_count - 4) * sizeof(int32_t);
+
+    entry_stack &= ~ABIStackAlignment;
+
+    // Store remaining arguments on stack, from low to high memory.
+    intptr_t* stack_argument = reinterpret_cast<intptr_t*>(entry_stack);
+    for (int i = 4; i < argument_count; i++)
+        stack_argument[i - 4] = va_arg(parameters, int32_t);
+    va_end(parameters);
+    set_register(sp, entry_stack);
+
+    callInternal(entry);
+
+    // Pop stack passed arguments.
+    MOZ_ASSERT(entry_stack == get_register(sp));
+    set_register(sp, original_stack);
+
+    int32_t result = get_register(r0);
+    return result;
+}
+
+Simulator*
+Simulator::Current()
+{
+    return TlsPerThreadData.get()->simulator();
+}
+
+} // namespace jit
+} // namespace js
+
+js::jit::Simulator*
+JSRuntime::simulator() const
+{
+    return simulator_;
+}
+
+uintptr_t*
+JSRuntime::addressOfSimulatorStackLimit()
+{
+    return simulator_->addressOfStackLimit();
+}
+
+js::jit::Simulator*
+js::PerThreadData::simulator() const
+{
+    return runtime_->simulator();
+}
diff --git a/js/src/jit/arm/Simulator-arm.h b/js/src/jit/arm/Simulator-arm.h
new file mode 100644
index 0000000000..968f460fbc
--- /dev/null
+++ b/js/src/jit/arm/Simulator-arm.h
@@ -0,0 +1,519 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
+// Copyright 2012 the V8 project authors. All rights reserved.
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+//       notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+//       copyright notice, this list of conditions and the following
+//       disclaimer in the documentation and/or other materials provided
+//       with the distribution.
+//     * Neither the name of Google Inc. nor the names of its
+//       contributors may be used to endorse or promote products derived
+//       from this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+#ifndef jit_arm_Simulator_arm_h
+#define jit_arm_Simulator_arm_h
+
+#ifdef JS_SIMULATOR_ARM
+
+#include "jit/arm/Architecture-arm.h"
+#include "jit/arm/disasm/Disasm-arm.h"
+#include "jit/IonTypes.h"
+#include "threading/Thread.h"
+#include "vm/MutexIDs.h"
+
+namespace js {
+namespace jit {
+
+class Simulator;
+class Redirection;
+class CachePage;
+class AutoLockSimulator;
+
+// When the SingleStepCallback is called, the simulator is about to execute
+// sim->get_pc() and the current machine state represents the completed
+// execution of the previous pc.
+typedef void (*SingleStepCallback)(void* arg, Simulator* sim, void* pc);
+
+// VFP rounding modes. See ARM DDI 0406B Page A2-29.
+enum VFPRoundingMode {
+    SimRN = 0 << 22,   // Round to Nearest.
+    SimRP = 1 << 22,   // Round towards Plus Infinity.
+    SimRM = 2 << 22,   // Round towards Minus Infinity.
+    SimRZ = 3 << 22,   // Round towards zero.
+
+    // Aliases.
+    kRoundToNearest = SimRN,
+    kRoundToPlusInf = SimRP,
+    kRoundToMinusInf = SimRM,
+    kRoundToZero = SimRZ
+};
+
+const uint32_t kVFPRoundingModeMask = 3 << 22;
+
+typedef int32_t Instr;
+class SimInstruction;
+
+class Simulator
+{
+    friend class Redirection;
+    friend class AutoLockSimulatorCache;
+
+  public:
+    friend class ArmDebugger;
+    enum Register {
+        no_reg = -1,
+        r0 = 0, r1, r2, r3, r4, r5, r6, r7,
+        r8, r9, r10, r11, r12, r13, r14, r15,
+        num_registers,
+        sp = 13,
+        lr = 14,
+        pc = 15,
+        s0 = 0, s1, s2, s3, s4, s5, s6, s7,
+        s8, s9, s10, s11, s12, s13, s14, s15,
+        s16, s17, s18, s19, s20, s21, s22, s23,
+        s24, s25, s26, s27, s28, s29, s30, s31,
+        num_s_registers = 32,
+        d0 = 0, d1, d2, d3, d4, d5, d6, d7,
+        d8, d9, d10, d11, d12, d13, d14, d15,
+        d16, d17, d18, d19, d20, d21, d22, d23,
+        d24, d25, d26, d27, d28, d29, d30, d31,
+        num_d_registers = 32,
+        q0 = 0, q1, q2, q3, q4, q5, q6, q7,
+        q8, q9, q10, q11, q12, q13, q14, q15,
+        num_q_registers = 16
+    };
+
+    // Returns nullptr on OOM.
+    static Simulator* Create(JSContext* cx);
+
+    static void Destroy(Simulator* simulator);
+
+    // Constructor/destructor are for internal use only; use the static methods above.
+    explicit Simulator(JSContext* cx);
+    ~Simulator();
+
+    // The currently executing Simulator instance. Potentially there can be one
+    // for each native thread.
+    static Simulator* Current();
+
+    static inline uintptr_t StackLimit() {
+        return Simulator::Current()->stackLimit();
+    }
+
+    // Disassemble some instructions starting at instr and print them
+    // on stdout.  Useful for working within GDB after a MOZ_CRASH(),
+    // among other things.
+    //
+    // Typical use within a crashed instruction decoding method is simply:
+    //
+    //   call Simulator::disassemble(instr, 1)
+    //
+    // or use one of the more convenient inline methods below.
+    static void disassemble(SimInstruction* instr, size_t n);
+
+    // Disassemble one instruction.
+    // "call disasm(instr)"
+    void disasm(SimInstruction* instr);
+
+    // Disassemble n instructions starting at instr.
+    // "call disasm(instr, 3)"
+    void disasm(SimInstruction* instr, size_t n);
+
+    // Skip backwards m instructions before starting, then disassemble n instructions.
+    // "call disasm(instr, 3, 7)"
+    void disasm(SimInstruction* instr, size_t m, size_t n);
+
+    uintptr_t* addressOfStackLimit();
+
+    // Accessors for register state. Reading the pc value adheres to the ARM
+    // architecture specification and is off by a 8 from the currently executing
+    // instruction.
+    void set_register(int reg, int32_t value);
+    int32_t get_register(int reg) const;
+    double get_double_from_register_pair(int reg);
+    void set_register_pair_from_double(int reg, double* value);
+    void set_dw_register(int dreg, const int* dbl);
+
+    // Support for VFP.
+    void get_d_register(int dreg, uint64_t* value);
+    void set_d_register(int dreg, const uint64_t* value);
+    void get_d_register(int dreg, uint32_t* value);
+    void set_d_register(int dreg, const uint32_t* value);
+    void get_q_register(int qreg, uint64_t* value);
+    void set_q_register(int qreg, const uint64_t* value);
+    void get_q_register(int qreg, uint32_t* value);
+    void set_q_register(int qreg, const uint32_t* value);
+    void set_s_register(int reg, unsigned int value);
+    unsigned int get_s_register(int reg) const;
+
+    void set_d_register_from_double(int dreg, const double& dbl) {
+        setVFPRegister<double, 2>(dreg, dbl);
+    }
+    void get_double_from_d_register(int dreg, double* out) {
+        getFromVFPRegister<double, 2>(dreg, out);
+    }
+    void set_s_register_from_float(int sreg, const float flt) {
+        setVFPRegister<float, 1>(sreg, flt);
+    }
+    void get_float_from_s_register(int sreg, float* out) {
+        getFromVFPRegister<float, 1>(sreg, out);
+    }
+    void set_s_register_from_sinteger(int sreg, const int sint) {
+        setVFPRegister<int, 1>(sreg, sint);
+    }
+    int get_sinteger_from_s_register(int sreg) {
+        int ret;
+        getFromVFPRegister<int, 1>(sreg, &ret);
+        return ret;
+    }
+
+    // Special case of set_register and get_register to access the raw PC value.
+    void set_pc(int32_t value);
+    int32_t get_pc() const;
+
+    template <typename T>
+    T get_pc_as() const { return reinterpret_cast<T>(get_pc()); }
+
+    void set_resume_pc(void* value) {
+        resume_pc_ = int32_t(value);
+    }
+
+    void enable_single_stepping(SingleStepCallback cb, void* arg);
+    void disable_single_stepping();
+
+    uintptr_t stackLimit() const;
+    bool overRecursed(uintptr_t newsp = 0) const;
+    bool overRecursedWithExtra(uint32_t extra) const;
+
+    // Executes ARM instructions until the PC reaches end_sim_pc.
+    template<bool EnableStopSimAt>
+    void execute();
+
+    // Sets up the simulator state and grabs the result on return.
+    int32_t call(uint8_t* entry, int argument_count, ...);
+
+    // Debugger input.
+    void setLastDebuggerInput(char* input);
+    char* lastDebuggerInput() { return lastDebuggerInput_; }
+
+    // Returns true if pc register contains one of the 'special_values' defined
+    // below (bad_lr, end_sim_pc).
+    bool has_bad_pc() const;
+
+  private:
+    enum special_values {
+        // Known bad pc value to ensure that the simulator does not execute
+        // without being properly setup.
+        bad_lr = -1,
+        // A pc value used to signal the simulator to stop execution. Generally
+        // the lr is set to this value on transition from native C code to
+        // simulated execution, so that the simulator can "return" to the native
+        // C code.
+        end_sim_pc = -2
+    };
+
+    // ForbidUnaligned means "always fault on unaligned access".
+    //
+    // AllowUnaligned means "allow the unaligned access if other conditions are
+    // met".  The "other conditions" vary with the instruction: For all
+    // instructions the base condition is !HasAlignmentFault(), ie, the chip is
+    // configured to allow unaligned accesses.  For instructions like VLD1
+    // there is an additional constraint that the alignment attribute in the
+    // instruction must be set to "default alignment".
+
+    enum UnalignedPolicy {
+        ForbidUnaligned,
+        AllowUnaligned
+    };
+
+    bool init();
+
+    // Checks if the current instruction should be executed based on its
+    // condition bits.
+    inline bool conditionallyExecute(SimInstruction* instr);
+
+    // Helper functions to set the conditional flags in the architecture state.
+    void setNZFlags(int32_t val);
+    void setCFlag(bool val);
+    void setVFlag(bool val);
+    bool carryFrom(int32_t left, int32_t right, int32_t carry = 0);
+    bool borrowFrom(int32_t left, int32_t right);
+    bool overflowFrom(int32_t alu_out, int32_t left, int32_t right, bool addition);
+
+    inline int getCarry() { return c_flag_ ? 1 : 0; };
+
+    // Support for VFP.
+    void compute_FPSCR_Flags(double val1, double val2);
+    void copy_FPSCR_to_APSR();
+    inline void canonicalizeNaN(double* value);
+    inline void canonicalizeNaN(float* value);
+
+    // Helper functions to decode common "addressing" modes
+    int32_t getShiftRm(SimInstruction* instr, bool* carry_out);
+    int32_t getImm(SimInstruction* instr, bool* carry_out);
+    int32_t processPU(SimInstruction* instr, int num_regs, int operand_size,
+                      intptr_t* start_address, intptr_t* end_address);
+    void handleRList(SimInstruction* instr, bool load);
+    void handleVList(SimInstruction* inst);
+    void softwareInterrupt(SimInstruction* instr);
+
+    // Stop helper functions.
+    inline bool isStopInstruction(SimInstruction* instr);
+    inline bool isWatchedStop(uint32_t bkpt_code);
+    inline bool isEnabledStop(uint32_t bkpt_code);
+    inline void enableStop(uint32_t bkpt_code);
+    inline void disableStop(uint32_t bkpt_code);
+    inline void increaseStopCounter(uint32_t bkpt_code);
+    void printStopInfo(uint32_t code);
+
+    // Handle any wasm faults, returning true if the fault was handled.
+    inline bool handleWasmFault(int32_t addr, unsigned numBytes);
+
+    // Read and write memory.
+    inline uint8_t readBU(int32_t addr);
+    inline int8_t readB(int32_t addr);
+    inline void writeB(int32_t addr, uint8_t value);
+    inline void writeB(int32_t addr, int8_t value);
+
+    inline uint8_t readExBU(int32_t addr);
+    inline int32_t writeExB(int32_t addr, uint8_t value);
+
+    inline uint16_t readHU(int32_t addr, SimInstruction* instr);
+    inline int16_t readH(int32_t addr, SimInstruction* instr);
+    // Note: Overloaded on the sign of the value.
+    inline void writeH(int32_t addr, uint16_t value, SimInstruction* instr);
+    inline void writeH(int32_t addr, int16_t value, SimInstruction* instr);
+
+    inline uint16_t readExHU(int32_t addr, SimInstruction* instr);
+    inline int32_t writeExH(int32_t addr, uint16_t value, SimInstruction* instr);
+
+    inline int readW(int32_t addr, SimInstruction* instr, UnalignedPolicy f = ForbidUnaligned);
+    inline void writeW(int32_t addr, int value, SimInstruction* instr, UnalignedPolicy f = ForbidUnaligned);
+
+    inline uint64_t readQ(int32_t addr, SimInstruction* instr, UnalignedPolicy f = ForbidUnaligned);
+    inline void writeQ(int32_t addr, uint64_t value, SimInstruction* instr, UnalignedPolicy f = ForbidUnaligned);
+
+    inline int readExW(int32_t addr, SimInstruction* instr);
+    inline int writeExW(int32_t addr, int value, SimInstruction* instr);
+
+    int32_t* readDW(int32_t addr);
+    void writeDW(int32_t addr, int32_t value1, int32_t value2);
+
+    int32_t readExDW(int32_t addr, int32_t* hibits);
+    int32_t writeExDW(int32_t addr, int32_t value1, int32_t value2);
+
+    // Executing is handled based on the instruction type.
+    // Both type 0 and type 1 rolled into one.
+    void decodeType01(SimInstruction* instr);
+    void decodeType2(SimInstruction* instr);
+    void decodeType3(SimInstruction* instr);
+    void decodeType4(SimInstruction* instr);
+    void decodeType5(SimInstruction* instr);
+    void decodeType6(SimInstruction* instr);
+    void decodeType7(SimInstruction* instr);
+
+    // Support for VFP.
+    void decodeTypeVFP(SimInstruction* instr);
+    void decodeType6CoprocessorIns(SimInstruction* instr);
+    void decodeSpecialCondition(SimInstruction* instr);
+
+    void decodeVMOVBetweenCoreAndSinglePrecisionRegisters(SimInstruction* instr);
+    void decodeVCMP(SimInstruction* instr);
+    void decodeVCVTBetweenDoubleAndSingle(SimInstruction* instr);
+    void decodeVCVTBetweenFloatingPointAndInteger(SimInstruction* instr);
+    void decodeVCVTBetweenFloatingPointAndIntegerFrac(SimInstruction* instr);
+
+    // Support for some system functions.
+    void decodeType7CoprocessorIns(SimInstruction* instr);
+
+    // Executes one instruction.
+    void instructionDecode(SimInstruction* instr);
+
+  public:
+    static bool ICacheCheckingEnabled;
+    static void FlushICache(void* start, size_t size);
+
+    static int64_t StopSimAt;
+
+    // For testing the MoveResolver code, a MoveResolver is set up, and
+    // the VFP registers are loaded with pre-determined values,
+    // then the sequence of code is simulated.  In order to test this with the
+    // simulator, the callee-saved registers can't be trashed. This flag
+    // disables that feature.
+    bool skipCalleeSavedRegsCheck;
+
+    // Runtime call support.
+    static void* RedirectNativeFunction(void* nativeFunction, ABIFunctionType type);
+
+  private:
+    // Handle arguments and return value for runtime FP functions.
+    void getFpArgs(double* x, double* y, int32_t* z);
+    void getFpFromStack(int32_t* stack, double* x1);
+    void setCallResultDouble(double result);
+    void setCallResultFloat(float result);
+    void setCallResult(int64_t res);
+    void scratchVolatileRegisters(bool scratchFloat = true);
+
+    template<class ReturnType, int register_size>
+    void getFromVFPRegister(int reg_index, ReturnType* out);
+
+    template<class InputType, int register_size>
+    void setVFPRegister(int reg_index, const InputType& value);
+
+    void callInternal(uint8_t* entry);
+
+    JSContext* const cx_;
+
+    // Architecture state.
+    // Saturating instructions require a Q flag to indicate saturation.
+    // There is currently no way to read the CPSR directly, and thus read the Q
+    // flag, so this is left unimplemented.
+    int32_t registers_[16];
+    bool n_flag_;
+    bool z_flag_;
+    bool c_flag_;
+    bool v_flag_;
+
+    // VFP architecture state.
+    uint32_t vfp_registers_[num_d_registers * 2];
+    bool n_flag_FPSCR_;
+    bool z_flag_FPSCR_;
+    bool c_flag_FPSCR_;
+    bool v_flag_FPSCR_;
+
+    // VFP rounding mode. See ARM DDI 0406B Page A2-29.
+    VFPRoundingMode FPSCR_rounding_mode_;
+    bool FPSCR_default_NaN_mode_;
+
+    // VFP FP exception flags architecture state.
+    bool inv_op_vfp_flag_;
+    bool div_zero_vfp_flag_;
+    bool overflow_vfp_flag_;
+    bool underflow_vfp_flag_;
+    bool inexact_vfp_flag_;
+
+    // Simulator support.
+    char* stack_;
+    uintptr_t stackLimit_;
+    bool pc_modified_;
+    int64_t icount_;
+
+    int32_t resume_pc_;
+
+    // Debugger input.
+    char* lastDebuggerInput_;
+
+    // Registered breakpoints.
+    SimInstruction* break_pc_;
+    Instr break_instr_;
+
+    // Single-stepping support
+    bool single_stepping_;
+    SingleStepCallback single_step_callback_;
+    void* single_step_callback_arg_;
+
+    // A stop is watched if its code is less than kNumOfWatchedStops.
+    // Only watched stops support enabling/disabling and the counter feature.
+    static const uint32_t kNumOfWatchedStops = 256;
+
+    // Breakpoint is disabled if bit 31 is set.
+    static const uint32_t kStopDisabledBit = 1 << 31;
+
+    // A stop is enabled, meaning the simulator will stop when meeting the
+    // instruction, if bit 31 of watched_stops_[code].count is unset.
+    // The value watched_stops_[code].count & ~(1 << 31) indicates how many times
+    // the breakpoint was hit or gone through.
+    struct StopCountAndDesc {
+        uint32_t count;
+        char* desc;
+    };
+    StopCountAndDesc watched_stops_[kNumOfWatchedStops];
+
+  public:
+    int64_t icount() {
+        return icount_;
+    }
+
+  private:
+    // ICache checking.
+    struct ICacheHasher {
+        typedef void* Key;
+        typedef void* Lookup;
+        static HashNumber hash(const Lookup& l);
+        static bool match(const Key& k, const Lookup& l);
+    };
+
+  public:
+    typedef HashMap<void*, CachePage*, ICacheHasher, SystemAllocPolicy> ICacheMap;
+
+  private:
+    // This lock creates a critical section around 'redirection_' and
+    // 'icache_', which are referenced both by the execution engine
+    // and by the off-thread compiler (see Redirection::Get in the cpp file).
+    Mutex cacheLock_;
+#ifdef DEBUG
+    mozilla::Maybe<Thread::Id> cacheLockHolder_;
+#endif
+
+    Redirection* redirection_;
+    ICacheMap icache_;
+
+  public:
+    ICacheMap& icache() {
+        // Technically we need the lock to access the innards of the
+        // icache, not to take its address, but the latter condition
+        // serves as a useful complement to the former.
+        MOZ_ASSERT(cacheLockHolder_.isSome());
+        return icache_;
+    }
+
+    Redirection* redirection() const {
+        MOZ_ASSERT(cacheLockHolder_.isSome());
+        return redirection_;
+    }
+
+    void setRedirection(js::jit::Redirection* redirection) {
+        MOZ_ASSERT(cacheLockHolder_.isSome());
+        redirection_ = redirection;
+    }
+
+  private:
+    // Exclusive access monitor
+    void exclusiveMonitorSet(uint64_t value);
+    uint64_t exclusiveMonitorGetAndClear(bool* held);
+    void exclusiveMonitorClear();
+
+    bool exclusiveMonitorHeld_;
+    uint64_t exclusiveMonitor_;
+};
+
+#define JS_CHECK_SIMULATOR_RECURSION_WITH_EXTRA(cx, extra, onerror)             \
+    JS_BEGIN_MACRO                                                              \
+        if (cx->runtime()->simulator()->overRecursedWithExtra(extra)) {         \
+            js::ReportOverRecursed(cx);                                         \
+            onerror;                                                            \
+        }                                                                       \
+    JS_END_MACRO
+
+} // namespace jit
+} // namespace js
+
+#endif /* JS_SIMULATOR_ARM */
+
+#endif /* jit_arm_Simulator_arm_h */
diff --git a/js/src/jit/arm/Trampoline-arm.cpp b/js/src/jit/arm/Trampoline-arm.cpp
new file mode 100644
index 0000000000..44144763c9
--- /dev/null
+++ b/js/src/jit/arm/Trampoline-arm.cpp
@@ -0,0 +1,1442 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "jscompartment.h"
+
+#include "jit/arm/SharedICHelpers-arm.h"
+#include "jit/Bailouts.h"
+#include "jit/JitCompartment.h"
+#include "jit/JitFrames.h"
+#include "jit/JitSpewer.h"
+#include "jit/Linker.h"
+#ifdef JS_ION_PERF
+# include "jit/PerfSpewer.h"
+#endif
+#include "jit/VMFunctions.h"
+
+#include "jit/MacroAssembler-inl.h"
+
+using namespace js;
+using namespace js::jit;
+
+static const FloatRegisterSet NonVolatileFloatRegs =
+    FloatRegisterSet((1ULL << FloatRegisters::d8) |
+                     (1ULL << FloatRegisters::d9) |
+                     (1ULL << FloatRegisters::d10) |
+                     (1ULL << FloatRegisters::d11) |
+                     (1ULL << FloatRegisters::d12) |
+                     (1ULL << FloatRegisters::d13) |
+                     (1ULL << FloatRegisters::d14) |
+                     (1ULL << FloatRegisters::d15));
+
+static void
+GenerateReturn(MacroAssembler& masm, int returnCode, SPSProfiler* prof)
+{
+    // Restore non-volatile floating point registers.
+    masm.transferMultipleByRuns(NonVolatileFloatRegs, IsLoad, StackPointer, IA);
+
+    // Get rid of padding word.
+    masm.addPtr(Imm32(sizeof(void*)), sp);
+
+    // Set up return value
+    masm.ma_mov(Imm32(returnCode), r0);
+
+    // Pop and return
+    masm.startDataTransferM(IsLoad, sp, IA, WriteBack);
+    masm.transferReg(r4);
+    masm.transferReg(r5);
+    masm.transferReg(r6);
+    masm.transferReg(r7);
+    masm.transferReg(r8);
+    masm.transferReg(r9);
+    masm.transferReg(r10);
+    masm.transferReg(r11);
+    // r12 isn't saved, so it shouldn't be restored.
+    masm.transferReg(pc);
+    masm.finishDataTransfer();
+    masm.flushBuffer();
+}
+
+struct EnterJITStack
+{
+    double d8;
+    double d9;
+    double d10;
+    double d11;
+    double d12;
+    double d13;
+    double d14;
+    double d15;
+
+    // Padding.
+    void* padding;
+
+    // Non-volatile registers.
+    void* r4;
+    void* r5;
+    void* r6;
+    void* r7;
+    void* r8;
+    void* r9;
+    void* r10;
+    void* r11;
+    // The abi does not expect r12 (ip) to be preserved
+    void* lr;
+
+    // Arguments.
+    // code == r0
+    // argc == r1
+    // argv == r2
+    // frame == r3
+    CalleeToken token;
+    JSObject* scopeChain;
+    size_t numStackValues;
+    Value* vp;
+};
+
+/*
+ * This method generates a trampoline for a c++ function with the following
+ * signature:
+ *   void enter(void* code, int argc, Value* argv, InterpreterFrame* fp, CalleeToken
+ *              calleeToken, JSObject* scopeChain, Value* vp)
+ *   ...using standard EABI calling convention
+ */
+JitCode*
+JitRuntime::generateEnterJIT(JSContext* cx, EnterJitType type)
+{
+    const Address slot_token(sp, offsetof(EnterJITStack, token));
+    const Address slot_vp(sp, offsetof(EnterJITStack, vp));
+
+    MOZ_ASSERT(OsrFrameReg == r3);
+
+    MacroAssembler masm(cx);
+    Assembler* aasm = &masm;
+
+    // Save non-volatile registers. These must be saved by the trampoline,
+    // rather than the JIT'd code, because they are scanned by the conservative
+    // scanner.
+    masm.startDataTransferM(IsStore, sp, DB, WriteBack);
+    masm.transferReg(r4); // [sp,0]
+    masm.transferReg(r5); // [sp,4]
+    masm.transferReg(r6); // [sp,8]
+    masm.transferReg(r7); // [sp,12]
+    masm.transferReg(r8); // [sp,16]
+    masm.transferReg(r9); // [sp,20]
+    masm.transferReg(r10); // [sp,24]
+    masm.transferReg(r11); // [sp,28]
+    // The abi does not expect r12 (ip) to be preserved
+    masm.transferReg(lr);  // [sp,32]
+    // The 5th argument is located at [sp, 36]
+    masm.finishDataTransfer();
+
+    // Add padding word.
+    masm.subPtr(Imm32(sizeof(void*)), sp);
+
+    // Push the float registers.
+    masm.transferMultipleByRuns(NonVolatileFloatRegs, IsStore, sp, DB);
+
+    // Save stack pointer into r8
+    masm.movePtr(sp, r8);
+
+    // Load calleeToken into r9.
+    masm.loadPtr(slot_token, r9);
+
+    // Save stack pointer.
+    if (type == EnterJitBaseline)
+        masm.movePtr(sp, r11);
+
+    // Load the number of actual arguments into r10.
+    masm.loadPtr(slot_vp, r10);
+    masm.unboxInt32(Address(r10, 0), r10);
+
+    {
+        Label noNewTarget;
+        masm.branchTest32(Assembler::Zero, r9, Imm32(CalleeToken_FunctionConstructing),
+                          &noNewTarget);
+
+        masm.add32(Imm32(1), r1);
+
+        masm.bind(&noNewTarget);
+    }
+
+    // Guarantee stack alignment of Jit frames.
+    //
+    // This code moves the stack pointer to the location where it should be when
+    // we enter the Jit frame.  It moves the stack pointer such that we have
+    // enough space reserved for pushing the arguments, and the JitFrameLayout.
+    // The stack pointer is also aligned on the alignment expected by the Jit
+    // frames.
+    //
+    // At the end the register r4, is a pointer to the stack where the first
+    // argument is expected by the Jit frame.
+    //
+    aasm->as_sub(r4, sp, O2RegImmShift(r1, LSL, 3));    // r4 = sp - argc*8
+    aasm->as_bic(r4, r4, Imm8(JitStackAlignment - 1));
+    // r4 is now the aligned on the bottom of the list of arguments.
+    static_assert(sizeof(JitFrameLayout) % JitStackAlignment == 0,
+      "No need to consider the JitFrameLayout for aligning the stack");
+    // sp' = ~(JitStackAlignment - 1) & (sp - argc * sizeof(Value)) - sizeof(JitFrameLayout)
+    aasm->as_sub(sp, r4, Imm8(sizeof(JitFrameLayout)));
+
+    // Get a copy of the number of args to use as a decrement counter, also set
+    // the zero condition code.
+    aasm->as_mov(r5, O2Reg(r1), SetCC);
+
+    // Loop over arguments, copying them from an unknown buffer onto the Ion
+    // stack so they can be accessed from JIT'ed code.
+    {
+        Label header, footer;
+        // If there aren't any arguments, don't do anything.
+        aasm->as_b(&footer, Assembler::Zero);
+        // Get the top of the loop.
+        masm.bind(&header);
+        aasm->as_sub(r5, r5, Imm8(1), SetCC);
+        // We could be more awesome, and unroll this, using a loadm
+        // (particularly since the offset is effectively 0) but that seems more
+        // error prone, and complex.
+        // BIG FAT WARNING: this loads both r6 and r7.
+        aasm->as_extdtr(IsLoad,  64, true, PostIndex, r6, EDtrAddr(r2, EDtrOffImm(8)));
+        aasm->as_extdtr(IsStore, 64, true, PostIndex, r6, EDtrAddr(r4, EDtrOffImm(8)));
+        aasm->as_b(&header, Assembler::NonZero);
+        masm.bind(&footer);
+    }
+
+    masm.ma_sub(r8, sp, r8);
+    masm.makeFrameDescriptor(r8, JitFrame_Entry, JitFrameLayout::Size());
+
+    masm.startDataTransferM(IsStore, sp, IB, NoWriteBack);
+                           // [sp]    = return address (written later)
+    masm.transferReg(r8);  // [sp',4] = descriptor, argc*8+20
+    masm.transferReg(r9);  // [sp',8]  = callee token
+    masm.transferReg(r10); // [sp',12]  = actual arguments
+    masm.finishDataTransfer();
+
+    Label returnLabel;
+    if (type == EnterJitBaseline) {
+        // Handle OSR.
+        AllocatableGeneralRegisterSet regs(GeneralRegisterSet::All());
+        regs.take(JSReturnOperand);
+        regs.takeUnchecked(OsrFrameReg);
+        regs.take(r11);
+        regs.take(ReturnReg);
+
+        const Address slot_numStackValues(r11, offsetof(EnterJITStack, numStackValues));
+
+        Label notOsr;
+        masm.branchTestPtr(Assembler::Zero, OsrFrameReg, OsrFrameReg, &notOsr);
+
+        Register scratch = regs.takeAny();
+
+        Register numStackValues = regs.takeAny();
+        masm.load32(slot_numStackValues, numStackValues);
+
+        // Write return address. On ARM, CodeLabel is only used for tableswitch,
+        // so we can't use it here to get the return address. Instead, we use pc
+        // + a fixed offset to a jump to returnLabel. The pc register holds pc +
+        // 8, so we add the size of 2 instructions to skip the instructions
+        // emitted by storePtr and jump(&skipJump).
+        {
+            AutoForbidPools afp(&masm, 5);
+            Label skipJump;
+            masm.mov(pc, scratch);
+            masm.addPtr(Imm32(2 * sizeof(uint32_t)), scratch);
+            masm.storePtr(scratch, Address(sp, 0));
+            masm.jump(&skipJump);
+            masm.jump(&returnLabel);
+            masm.bind(&skipJump);
+        }
+
+        // Push previous frame pointer.
+        masm.push(r11);
+
+        // Reserve frame.
+        Register framePtr = r11;
+        masm.subPtr(Imm32(BaselineFrame::Size()), sp);
+        masm.mov(sp, framePtr);
+
+#ifdef XP_WIN
+        // Can't push large frames blindly on windows. Touch frame memory
+        // incrementally.
+        masm.ma_lsl(Imm32(3), numStackValues, scratch);
+        masm.subPtr(scratch, framePtr);
+        {
+            masm.ma_sub(sp, Imm32(WINDOWS_BIG_FRAME_TOUCH_INCREMENT), scratch);
+
+            Label touchFrameLoop;
+            Label touchFrameLoopEnd;
+            masm.bind(&touchFrameLoop);
+            masm.branchPtr(Assembler::Below, scratch, framePtr, &touchFrameLoopEnd);
+            masm.store32(Imm32(0), Address(scratch, 0));
+            masm.subPtr(Imm32(WINDOWS_BIG_FRAME_TOUCH_INCREMENT), scratch);
+            masm.jump(&touchFrameLoop);
+            masm.bind(&touchFrameLoopEnd);
+        }
+        masm.mov(sp, framePtr);
+#endif
+
+        // Reserve space for locals and stack values.
+        masm.ma_lsl(Imm32(3), numStackValues, scratch);
+        masm.ma_sub(sp, scratch, sp);
+
+        // Enter exit frame.
+        masm.addPtr(Imm32(BaselineFrame::Size() + BaselineFrame::FramePointerOffset), scratch);
+        masm.makeFrameDescriptor(scratch, JitFrame_BaselineJS, ExitFrameLayout::Size());
+        masm.push(scratch);
+        masm.push(Imm32(0)); // Fake return address.
+        // No GC things to mark on the stack, push a bare token.
+        masm.enterFakeExitFrame(ExitFrameLayoutBareToken);
+
+        masm.push(framePtr); // BaselineFrame
+        masm.push(r0); // jitcode
+
+        masm.setupUnalignedABICall(scratch);
+        masm.passABIArg(r11); // BaselineFrame
+        masm.passABIArg(OsrFrameReg); // InterpreterFrame
+        masm.passABIArg(numStackValues);
+        masm.callWithABI(JS_FUNC_TO_DATA_PTR(void*, jit::InitBaselineFrameForOsr));
+
+        Register jitcode = regs.takeAny();
+        masm.pop(jitcode);
+        masm.pop(framePtr);
+
+        MOZ_ASSERT(jitcode != ReturnReg);
+
+        Label error;
+        masm.addPtr(Imm32(ExitFrameLayout::SizeWithFooter()), sp);
+        masm.addPtr(Imm32(BaselineFrame::Size()), framePtr);
+        masm.branchIfFalseBool(ReturnReg, &error);
+
+        // If OSR-ing, then emit instrumentation for setting lastProfilerFrame
+        // if profiler instrumentation is enabled.
+        {
+            Label skipProfilingInstrumentation;
+            Register realFramePtr = numStackValues;
+            AbsoluteAddress addressOfEnabled(cx->runtime()->spsProfiler.addressOfEnabled());
+            masm.branch32(Assembler::Equal, addressOfEnabled, Imm32(0),
+                          &skipProfilingInstrumentation);
+            masm.as_add(realFramePtr, framePtr, Imm8(sizeof(void*)));
+            masm.profilerEnterFrame(realFramePtr, scratch);
+            masm.bind(&skipProfilingInstrumentation);
+        }
+
+        masm.jump(jitcode);
+
+        // OOM: Load error value, discard return address and previous frame
+        // pointer and return.
+        masm.bind(&error);
+        masm.mov(framePtr, sp);
+        masm.addPtr(Imm32(2 * sizeof(uintptr_t)), sp);
+        masm.moveValue(MagicValue(JS_ION_ERROR), JSReturnOperand);
+        masm.jump(&returnLabel);
+
+        masm.bind(&notOsr);
+        // Load the scope chain in R1.
+        MOZ_ASSERT(R1.scratchReg() != r0);
+        masm.loadPtr(Address(r11, offsetof(EnterJITStack, scopeChain)), R1.scratchReg());
+    }
+
+    // The Data transfer is pushing 4 words, which already account for the
+    // return address space of the Jit frame.  We have to undo what the data
+    // transfer did before making the call.
+    masm.addPtr(Imm32(sizeof(uintptr_t)), sp);
+
+    // The callee will push the return address on the stack, thus we check that
+    // the stack would be aligned once the call is complete.
+    masm.assertStackAlignment(JitStackAlignment, sizeof(uintptr_t));
+
+    // Call the function.
+    masm.callJitNoProfiler(r0);
+
+    if (type == EnterJitBaseline) {
+        // Baseline OSR will return here.
+        masm.bind(&returnLabel);
+    }
+
+    // The top of the stack now points to the address of the field following the
+    // return address because the return address is popped for the return, so we
+    // need to remove the size of the return address field.
+    aasm->as_sub(sp, sp, Imm8(4));
+
+    // Load off of the stack the size of our local stack.
+    masm.loadPtr(Address(sp, JitFrameLayout::offsetOfDescriptor()), r5);
+    aasm->as_add(sp, sp, lsr(r5, FRAMESIZE_SHIFT));
+
+    // Store the returned value into the slot_vp
+    masm.loadPtr(slot_vp, r5);
+    masm.storeValue(JSReturnOperand, Address(r5, 0));
+
+    // :TODO: Optimize storeValue with:
+    // We're using a load-double here. In order for that to work, the data needs
+    // to be stored in two consecutive registers, make sure this is the case
+    //   MOZ_ASSERT(JSReturnReg_Type.code() == JSReturnReg_Data.code()+1);
+    //   aasm->as_extdtr(IsStore, 64, true, Offset,
+    //                   JSReturnReg_Data, EDtrAddr(r5, EDtrOffImm(0)));
+
+    // Restore non-volatile registers and return.
+    GenerateReturn(masm, true, &cx->runtime()->spsProfiler);
+
+    Linker linker(masm);
+    AutoFlushICache afc("EnterJIT");
+    JitCode* code = linker.newCode<NoGC>(cx, OTHER_CODE);
+
+#ifdef JS_ION_PERF
+    writePerfSpewerJitCodeProfile(code, "EnterJIT");
+#endif
+
+    return code;
+}
+
+JitCode*
+JitRuntime::generateInvalidator(JSContext* cx)
+{
+    // See large comment in x86's JitRuntime::generateInvalidator.
+    MacroAssembler masm(cx);
+    // At this point, one of two things has happened:
+    // 1) Execution has just returned from C code, which left the stack aligned
+    // 2) Execution has just returned from Ion code, which left the stack unaligned.
+    // The old return address should not matter, but we still want the stack to
+    // be aligned, and there is no good reason to automatically align it with a
+    // call to setupUnalignedABICall.
+    masm.as_bic(sp, sp, Imm8(7));
+    masm.startDataTransferM(IsStore, sp, DB, WriteBack);
+    // We don't have to push everything, but this is likely easier.
+    // Setting regs_.
+    for (uint32_t i = 0; i < Registers::Total; i++)
+        masm.transferReg(Register::FromCode(i));
+    masm.finishDataTransfer();
+
+    // Since our datastructures for stack inspection are compile-time fixed,
+    // if there are only 16 double registers, then we need to reserve
+    // space on the stack for the missing 16.
+    if (FloatRegisters::ActualTotalPhys() != FloatRegisters::TotalPhys) {
+        ScratchRegisterScope scratch(masm);
+        int missingRegs = FloatRegisters::TotalPhys - FloatRegisters::ActualTotalPhys();
+        masm.ma_sub(Imm32(missingRegs * sizeof(double)), sp, scratch);
+    }
+
+    masm.startFloatTransferM(IsStore, sp, DB, WriteBack);
+    for (uint32_t i = 0; i < FloatRegisters::ActualTotalPhys(); i++)
+        masm.transferFloatReg(FloatRegister(i, FloatRegister::Double));
+    masm.finishFloatTransfer();
+
+    masm.ma_mov(sp, r0);
+    const int sizeOfRetval = sizeof(size_t)*2;
+    masm.reserveStack(sizeOfRetval);
+    masm.mov(sp, r1);
+    const int sizeOfBailoutInfo = sizeof(void*)*2;
+    masm.reserveStack(sizeOfBailoutInfo);
+    masm.mov(sp, r2);
+    masm.setupAlignedABICall();
+    masm.passABIArg(r0);
+    masm.passABIArg(r1);
+    masm.passABIArg(r2);
+    masm.callWithABI(JS_FUNC_TO_DATA_PTR(void*, InvalidationBailout));
+
+    masm.ma_ldr(DTRAddr(sp, DtrOffImm(0)), r2);
+    {
+        ScratchRegisterScope scratch(masm);
+        masm.ma_ldr(Address(sp, sizeOfBailoutInfo), r1, scratch);
+    }
+    // Remove the return address, the IonScript, the register state
+    // (InvaliationBailoutStack) and the space that was allocated for the return
+    // value.
+    {
+        ScratchRegisterScope scratch(masm);
+        masm.ma_add(sp, Imm32(sizeof(InvalidationBailoutStack) + sizeOfRetval + sizeOfBailoutInfo), sp, scratch);
+    }
+    // Remove the space that this frame was using before the bailout (computed
+    // by InvalidationBailout)
+    masm.ma_add(sp, r1, sp);
+
+    // Jump to shared bailout tail. The BailoutInfo pointer has to be in r2.
+    JitCode* bailoutTail = cx->runtime()->jitRuntime()->getBailoutTail();
+    masm.branch(bailoutTail);
+
+    Linker linker(masm);
+    AutoFlushICache afc("Invalidator");
+    JitCode* code = linker.newCode<NoGC>(cx, OTHER_CODE);
+    JitSpew(JitSpew_IonInvalidate, "   invalidation thunk created at %p", (void*) code->raw());
+
+#ifdef JS_ION_PERF
+    writePerfSpewerJitCodeProfile(code, "Invalidator");
+#endif
+
+    return code;
+}
+
+JitCode*
+JitRuntime::generateArgumentsRectifier(JSContext* cx, void** returnAddrOut)
+{
+    MacroAssembler masm(cx);
+    masm.pushReturnAddress();
+
+    // ArgumentsRectifierReg contains the |nargs| pushed onto the current frame.
+    // Including |this|, there are (|nargs| + 1) arguments to copy.
+    MOZ_ASSERT(ArgumentsRectifierReg == r8);
+
+    // Copy number of actual arguments into r0.
+    masm.ma_ldr(DTRAddr(sp, DtrOffImm(RectifierFrameLayout::offsetOfNumActualArgs())), r0);
+
+    // Load the number of |undefined|s to push into r6.
+    masm.ma_ldr(DTRAddr(sp, DtrOffImm(RectifierFrameLayout::offsetOfCalleeToken())), r1);
+    {
+        ScratchRegisterScope scratch(masm);
+        masm.ma_and(Imm32(CalleeTokenMask), r1, r6, scratch);
+    }
+    masm.ma_ldrh(EDtrAddr(r6, EDtrOffImm(JSFunction::offsetOfNargs())), r6);
+
+    masm.ma_sub(r6, r8, r2);
+
+    // Get the topmost argument.
+    {
+        ScratchRegisterScope scratch(masm);
+        masm.ma_alu(sp, lsl(r8, 3), r3, OpAdd); // r3 <- r3 + nargs * 8
+        masm.ma_add(r3, Imm32(sizeof(RectifierFrameLayout)), r3, scratch);
+    }
+
+    {
+        Label notConstructing;
+
+        masm.branchTest32(Assembler::Zero, r1, Imm32(CalleeToken_FunctionConstructing),
+                          &notConstructing);
+
+        // Add sizeof(Value) to overcome |this|
+        masm.as_extdtr(IsLoad, 64, true, Offset, r4, EDtrAddr(r3, EDtrOffImm(8)));
+        masm.as_extdtr(IsStore, 64, true, PreIndex, r4, EDtrAddr(sp, EDtrOffImm(-8)));
+
+        // Include the newly pushed newTarget value in the frame size
+        // calculated below.
+        masm.add32(Imm32(1), r6);
+
+        masm.bind(&notConstructing);
+    }
+
+    // Push undefined.
+    masm.moveValue(UndefinedValue(), r5, r4);
+    {
+        Label undefLoopTop;
+        masm.bind(&undefLoopTop);
+        masm.as_extdtr(IsStore, 64, true, PreIndex, r4, EDtrAddr(sp, EDtrOffImm(-8)));
+        masm.as_sub(r2, r2, Imm8(1), SetCC);
+
+        masm.ma_b(&undefLoopTop, Assembler::NonZero);
+    }
+
+    // Push arguments, |nargs| + 1 times (to include |this|).
+    {
+        Label copyLoopTop;
+        masm.bind(&copyLoopTop);
+        masm.as_extdtr(IsLoad, 64, true, PostIndex, r4, EDtrAddr(r3, EDtrOffImm(-8)));
+        masm.as_extdtr(IsStore, 64, true, PreIndex, r4, EDtrAddr(sp, EDtrOffImm(-8)));
+
+        masm.as_sub(r8, r8, Imm8(1), SetCC);
+        masm.ma_b(&copyLoopTop, Assembler::NotSigned);
+    }
+
+    // translate the framesize from values into bytes
+    masm.as_add(r6, r6, Imm8(1));
+    masm.ma_lsl(Imm32(3), r6, r6);
+
+    // Construct sizeDescriptor.
+    masm.makeFrameDescriptor(r6, JitFrame_Rectifier, JitFrameLayout::Size());
+
+    // Construct JitFrameLayout.
+    masm.ma_push(r0); // actual arguments.
+    masm.ma_push(r1); // callee token
+    masm.ma_push(r6); // frame descriptor.
+
+    // Call the target function.
+    // Note that this code assumes the function is JITted.
+    masm.andPtr(Imm32(CalleeTokenMask), r1);
+    masm.ma_ldr(DTRAddr(r1, DtrOffImm(JSFunction::offsetOfNativeOrScript())), r3);
+    masm.loadBaselineOrIonRaw(r3, r3, nullptr);
+    uint32_t returnOffset = masm.callJitNoProfiler(r3);
+
+    // arg1
+    //  ...
+    // argN
+    // num actual args
+    // callee token
+    // sizeDescriptor     <- sp now
+    // return address
+
+    // Remove the rectifier frame.
+    {
+        ScratchRegisterScope scratch(masm);
+        masm.ma_dtr(IsLoad, sp, Imm32(12), r4, scratch, PostIndex);
+    }
+
+    // arg1
+    //  ...
+    // argN               <- sp now; r4 <- frame descriptor
+    // num actual args
+    // callee token
+    // sizeDescriptor
+    // return address
+
+    // Discard pushed arguments.
+    masm.ma_alu(sp, lsr(r4, FRAMESIZE_SHIFT), sp, OpAdd);
+
+    masm.ret();
+    Linker linker(masm);
+    AutoFlushICache afc("ArgumentsRectifier");
+    JitCode* code = linker.newCode<NoGC>(cx, OTHER_CODE);
+
+    if (returnAddrOut)
+        *returnAddrOut = (void*) (code->raw() + returnOffset);
+
+#ifdef JS_ION_PERF
+    writePerfSpewerJitCodeProfile(code, "ArgumentsRectifier");
+#endif
+
+    return code;
+}
+
+static void
+PushBailoutFrame(MacroAssembler& masm, uint32_t frameClass, Register spArg)
+{
+    // the stack should look like:
+    // [IonFrame]
+    // bailoutFrame.registersnapshot
+    // bailoutFrame.fpsnapshot
+    // bailoutFrame.snapshotOffset
+    // bailoutFrame.frameSize
+
+    // STEP 1a: Save our register sets to the stack so Bailout() can read
+    // everything.
+    // sp % 8 == 0
+
+    masm.startDataTransferM(IsStore, sp, DB, WriteBack);
+    // We don't have to push everything, but this is likely easier.
+    // Setting regs_.
+    for (uint32_t i = 0; i < Registers::Total; i++)
+        masm.transferReg(Register::FromCode(i));
+    masm.finishDataTransfer();
+
+    ScratchRegisterScope scratch(masm);
+
+    // Since our datastructures for stack inspection are compile-time fixed,
+    // if there are only 16 double registers, then we need to reserve
+    // space on the stack for the missing 16.
+    if (FloatRegisters::ActualTotalPhys() != FloatRegisters::TotalPhys) {
+        int missingRegs = FloatRegisters::TotalPhys - FloatRegisters::ActualTotalPhys();
+        masm.ma_sub(Imm32(missingRegs * sizeof(double)), sp, scratch);
+    }
+    masm.startFloatTransferM(IsStore, sp, DB, WriteBack);
+    for (uint32_t i = 0; i < FloatRegisters::ActualTotalPhys(); i++)
+        masm.transferFloatReg(FloatRegister(i, FloatRegister::Double));
+    masm.finishFloatTransfer();
+
+    // STEP 1b: Push both the "return address" of the function call (the address
+    //          of the instruction after the call that we used to get here) as
+    //          well as the callee token onto the stack. The return address is
+    //          currently in r14. We will proceed by loading the callee token
+    //          into a sacrificial register <= r14, then pushing both onto the
+    //          stack.
+
+    // Now place the frameClass onto the stack, via a register.
+    masm.ma_mov(Imm32(frameClass), r4);
+    // And onto the stack. Since the stack is full, we need to put this one past
+    // the end of the current stack. Sadly, the ABI says that we need to always
+    // point to the lowest place that has been written. The OS is free to do
+    // whatever it wants below sp.
+    masm.startDataTransferM(IsStore, sp, DB, WriteBack);
+    // Set frameClassId_.
+    masm.transferReg(r4);
+    // Set tableOffset_; higher registers are stored at higher locations on the
+    // stack.
+    masm.transferReg(lr);
+    masm.finishDataTransfer();
+
+    masm.ma_mov(sp, spArg);
+}
+
+static void
+GenerateBailoutThunk(JSContext* cx, MacroAssembler& masm, uint32_t frameClass)
+{
+    PushBailoutFrame(masm, frameClass, r0);
+
+    // SP % 8 == 4
+    // STEP 1c: Call the bailout function, giving a pointer to the
+    //          structure we just blitted onto the stack.
+    const int sizeOfBailoutInfo = sizeof(void*)*2;
+    masm.reserveStack(sizeOfBailoutInfo);
+    masm.mov(sp, r1);
+    masm.setupAlignedABICall();
+
+    // Decrement sp by another 4, so we keep alignment. Not Anymore! Pushing
+    // both the snapshotoffset as well as the: masm.as_sub(sp, sp, Imm8(4));
+
+    // Set the old (4-byte aligned) value of the sp as the first argument.
+    masm.passABIArg(r0);
+    masm.passABIArg(r1);
+
+    // Sp % 8 == 0
+    masm.callWithABI(JS_FUNC_TO_DATA_PTR(void*, Bailout));
+    masm.ma_ldr(DTRAddr(sp, DtrOffImm(0)), r2);
+    {
+        ScratchRegisterScope scratch(masm);
+        masm.ma_add(sp, Imm32(sizeOfBailoutInfo), sp, scratch);
+    }
+
+    // Common size of a bailout frame.
+    uint32_t bailoutFrameSize = 0
+        + sizeof(void*) // frameClass
+        + sizeof(RegisterDump);
+
+    if (frameClass == NO_FRAME_SIZE_CLASS_ID) {
+        // Make sure the bailout frame size fits into the offset for a load.
+        masm.as_dtr(IsLoad, 32, Offset,
+                    r4, DTRAddr(sp, DtrOffImm(4)));
+        // Used to be: offsetof(BailoutStack, frameSize_)
+        // This structure is no longer available to us :(
+        // We add 12 to the bailoutFrameSize because:
+        // sizeof(uint32_t) for the tableOffset that was pushed onto the stack
+        // sizeof(uintptr_t) for the snapshotOffset;
+        // alignment to round the uintptr_t up to a multiple of 8 bytes.
+        ScratchRegisterScope scratch(masm);
+        masm.ma_add(sp, Imm32(bailoutFrameSize+12), sp, scratch);
+        masm.as_add(sp, sp, O2Reg(r4));
+    } else {
+        ScratchRegisterScope scratch(masm);
+        uint32_t frameSize = FrameSizeClass::FromClass(frameClass).frameSize();
+        masm.ma_add(Imm32(// The frame that was added when we entered the most
+                          // recent function.
+                          frameSize
+                          // The size of the "return address" that was dumped on
+                          // the stack.
+                          + sizeof(void*)
+                          // Everything else that was pushed on the stack.
+                          + bailoutFrameSize)
+                    , sp, scratch);
+    }
+
+    // Jump to shared bailout tail. The BailoutInfo pointer has to be in r2.
+    JitCode* bailoutTail = cx->runtime()->jitRuntime()->getBailoutTail();
+    masm.branch(bailoutTail);
+}
+
+JitCode*
+JitRuntime::generateBailoutTable(JSContext* cx, uint32_t frameClass)
+{
+    MacroAssembler masm(cx);
+
+    {
+        // Emit the table without any pools being inserted.
+        Label bailout;
+        AutoForbidPools afp(&masm, BAILOUT_TABLE_SIZE);
+        for (size_t i = 0; i < BAILOUT_TABLE_SIZE; i++)
+            masm.ma_bl(&bailout);
+        masm.bind(&bailout);
+    }
+
+    GenerateBailoutThunk(cx, masm, frameClass);
+
+    Linker linker(masm);
+    AutoFlushICache afc("BailoutTable");
+    JitCode* code = linker.newCode<NoGC>(cx, OTHER_CODE);
+
+#ifdef JS_ION_PERF
+    writePerfSpewerJitCodeProfile(code, "BailoutTable");
+#endif
+
+    return code;
+}
+
+JitCode*
+JitRuntime::generateBailoutHandler(JSContext* cx)
+{
+    MacroAssembler masm(cx);
+    GenerateBailoutThunk(cx, masm, NO_FRAME_SIZE_CLASS_ID);
+
+    Linker linker(masm);
+    AutoFlushICache afc("BailoutHandler");
+    JitCode* code = linker.newCode<NoGC>(cx, OTHER_CODE);
+
+#ifdef JS_ION_PERF
+    writePerfSpewerJitCodeProfile(code, "BailoutHandler");
+#endif
+
+    return code;
+}
+
+JitCode*
+JitRuntime::generateVMWrapper(JSContext* cx, const VMFunction& f)
+{
+    MOZ_ASSERT(functionWrappers_);
+    MOZ_ASSERT(functionWrappers_->initialized());
+    VMWrapperMap::AddPtr p = functionWrappers_->lookupForAdd(&f);
+    if (p)
+        return p->value();
+
+    // Generate a separated code for the wrapper.
+    MacroAssembler masm(cx);
+    AllocatableGeneralRegisterSet regs(Register::Codes::WrapperMask);
+
+    // Wrapper register set is a superset of Volatile register set.
+    JS_STATIC_ASSERT((Register::Codes::VolatileMask & ~Register::Codes::WrapperMask) == 0);
+
+    // The context is the first argument; r0 is the first argument register.
+    Register cxreg = r0;
+    regs.take(cxreg);
+
+    // Stack is:
+    //    ... frame ...
+    //  +8  [args] + argPadding
+    //  +0  ExitFrame
+    //
+    // We're aligned to an exit frame, so link it up.
+    // If it isn't a tail call, then the return address needs to be saved
+    if (f.expectTailCall == NonTailCall)
+        masm.pushReturnAddress();
+
+    masm.enterExitFrame(&f);
+    masm.loadJSContext(cxreg);
+
+    // Save the base of the argument set stored on the stack.
+    Register argsBase = InvalidReg;
+    if (f.explicitArgs) {
+        argsBase = r5;
+        regs.take(argsBase);
+        ScratchRegisterScope scratch(masm);
+        masm.ma_add(sp, Imm32(ExitFrameLayout::SizeWithFooter()), argsBase, scratch);
+    }
+
+    // Reserve space for the outparameter.
+    Register outReg = InvalidReg;
+    switch (f.outParam) {
+      case Type_Value:
+        outReg = r4;
+        regs.take(outReg);
+        masm.reserveStack(sizeof(Value));
+        masm.ma_mov(sp, outReg);
+        break;
+
+      case Type_Handle:
+        outReg = r4;
+        regs.take(outReg);
+        masm.PushEmptyRooted(f.outParamRootType);
+        masm.ma_mov(sp, outReg);
+        break;
+
+      case Type_Int32:
+      case Type_Pointer:
+      case Type_Bool:
+        outReg = r4;
+        regs.take(outReg);
+        masm.reserveStack(sizeof(int32_t));
+        masm.ma_mov(sp, outReg);
+        break;
+
+      case Type_Double:
+        outReg = r4;
+        regs.take(outReg);
+        masm.reserveStack(sizeof(double));
+        masm.ma_mov(sp, outReg);
+        break;
+
+      default:
+        MOZ_ASSERT(f.outParam == Type_Void);
+        break;
+    }
+
+    if (!generateTLEnterVM(cx, masm, f))
+        return nullptr;
+
+    masm.setupUnalignedABICall(regs.getAny());
+    masm.passABIArg(cxreg);
+
+    size_t argDisp = 0;
+
+    // Copy any arguments.
+    for (uint32_t explicitArg = 0; explicitArg < f.explicitArgs; explicitArg++) {
+        MoveOperand from;
+        switch (f.argProperties(explicitArg)) {
+          case VMFunction::WordByValue:
+            masm.passABIArg(MoveOperand(argsBase, argDisp), MoveOp::GENERAL);
+            argDisp += sizeof(void*);
+            break;
+          case VMFunction::DoubleByValue:
+            // Values should be passed by reference, not by value, so we assert
+            // that the argument is a double-precision float.
+            MOZ_ASSERT(f.argPassedInFloatReg(explicitArg));
+            masm.passABIArg(MoveOperand(argsBase, argDisp), MoveOp::DOUBLE);
+            argDisp += sizeof(double);
+            break;
+          case VMFunction::WordByRef:
+            masm.passABIArg(MoveOperand(argsBase, argDisp, MoveOperand::EFFECTIVE_ADDRESS), MoveOp::GENERAL);
+            argDisp += sizeof(void*);
+            break;
+          case VMFunction::DoubleByRef:
+            masm.passABIArg(MoveOperand(argsBase, argDisp, MoveOperand::EFFECTIVE_ADDRESS), MoveOp::GENERAL);
+            argDisp += 2 * sizeof(void*);
+            break;
+        }
+    }
+
+    // Copy the implicit outparam, if any.
+    if (outReg != InvalidReg)
+        masm.passABIArg(outReg);
+
+    masm.callWithABI(f.wrapped);
+
+    if (!generateTLExitVM(cx, masm, f))
+        return nullptr;
+
+    // Test for failure.
+    switch (f.failType()) {
+      case Type_Object:
+        masm.branchTestPtr(Assembler::Zero, r0, r0, masm.failureLabel());
+        break;
+      case Type_Bool:
+        masm.branchIfFalseBool(r0, masm.failureLabel());
+        break;
+      default:
+        MOZ_CRASH("unknown failure kind");
+    }
+
+    // Load the outparam and free any allocated stack.
+    switch (f.outParam) {
+      case Type_Handle:
+        masm.popRooted(f.outParamRootType, ReturnReg, JSReturnOperand);
+        break;
+
+      case Type_Value:
+        masm.loadValue(Address(sp, 0), JSReturnOperand);
+        masm.freeStack(sizeof(Value));
+        break;
+
+      case Type_Int32:
+      case Type_Pointer:
+        masm.load32(Address(sp, 0), ReturnReg);
+        masm.freeStack(sizeof(int32_t));
+        break;
+
+      case Type_Bool:
+        masm.load8ZeroExtend(Address(sp, 0), ReturnReg);
+        masm.freeStack(sizeof(int32_t));
+        break;
+
+      case Type_Double:
+        if (cx->runtime()->jitSupportsFloatingPoint)
+            masm.loadDouble(Address(sp, 0), ReturnDoubleReg);
+        else
+            masm.assumeUnreachable("Unable to load into float reg, with no FP support.");
+        masm.freeStack(sizeof(double));
+        break;
+
+      default:
+        MOZ_ASSERT(f.outParam == Type_Void);
+        break;
+    }
+    masm.leaveExitFrame();
+    masm.retn(Imm32(sizeof(ExitFrameLayout) +
+                    f.explicitStackSlots() * sizeof(void*) +
+                    f.extraValuesToPop * sizeof(Value)));
+
+    Linker linker(masm);
+    AutoFlushICache afc("VMWrapper");
+    JitCode* wrapper = linker.newCode<NoGC>(cx, OTHER_CODE);
+    if (!wrapper)
+        return nullptr;
+
+    // linker.newCode may trigger a GC and sweep functionWrappers_ so we have to
+    // use relookupOrAdd instead of add.
+    if (!functionWrappers_->relookupOrAdd(p, &f, wrapper))
+        return nullptr;
+
+#ifdef JS_ION_PERF
+    writePerfSpewerJitCodeProfile(wrapper, "VMWrapper");
+#endif
+
+    return wrapper;
+}
+
+JitCode*
+JitRuntime::generatePreBarrier(JSContext* cx, MIRType type)
+{
+    MacroAssembler masm(cx);
+
+    LiveRegisterSet save;
+    if (cx->runtime()->jitSupportsFloatingPoint) {
+        save.set() = RegisterSet(GeneralRegisterSet(Registers::VolatileMask),
+                                 FloatRegisterSet(FloatRegisters::VolatileDoubleMask));
+    } else {
+        save.set() = RegisterSet(GeneralRegisterSet(Registers::VolatileMask),
+                                 FloatRegisterSet());
+    }
+    save.add(lr);
+    masm.PushRegsInMask(save);
+
+    MOZ_ASSERT(PreBarrierReg == r1);
+    masm.movePtr(ImmPtr(cx->runtime()), r0);
+
+    masm.setupUnalignedABICall(r2);
+    masm.passABIArg(r0);
+    masm.passABIArg(r1);
+    masm.callWithABI(IonMarkFunction(type));
+    save.take(AnyRegister(lr));
+    save.add(pc);
+    masm.PopRegsInMask(save);
+
+    Linker linker(masm);
+    AutoFlushICache afc("PreBarrier");
+    JitCode* code = linker.newCode<NoGC>(cx, OTHER_CODE);
+
+#ifdef JS_ION_PERF
+    writePerfSpewerJitCodeProfile(code, "PreBarrier");
+#endif
+
+    return code;
+}
+
+typedef bool (*HandleDebugTrapFn)(JSContext*, BaselineFrame*, uint8_t*, bool*);
+static const VMFunction HandleDebugTrapInfo =
+    FunctionInfo<HandleDebugTrapFn>(HandleDebugTrap, "HandleDebugTrap");
+
+JitCode*
+JitRuntime::generateDebugTrapHandler(JSContext* cx)
+{
+    MacroAssembler masm;
+
+    Register scratch1 = r0;
+    Register scratch2 = r1;
+
+    // Load BaselineFrame pointer in scratch1.
+    masm.mov(r11, scratch1);
+    masm.subPtr(Imm32(BaselineFrame::Size()), scratch1);
+
+    // Enter a stub frame and call the HandleDebugTrap VM function. Ensure the
+    // stub frame has a nullptr ICStub pointer, since this pointer is marked
+    // during GC.
+    masm.movePtr(ImmPtr(nullptr), ICStubReg);
+    EmitBaselineEnterStubFrame(masm, scratch2);
+
+    JitCode* code = cx->runtime()->jitRuntime()->getVMWrapper(HandleDebugTrapInfo);
+    if (!code)
+        return nullptr;
+
+    masm.push(lr);
+    masm.push(scratch1);
+    EmitBaselineCallVM(code, masm);
+
+    EmitBaselineLeaveStubFrame(masm);
+
+    // If the stub returns |true|, we have to perform a forced return (return
+    // from the JS frame). If the stub returns |false|, just return from the
+    // trap stub so that execution continues at the current pc.
+    Label forcedReturn;
+    masm.branchTest32(Assembler::NonZero, ReturnReg, ReturnReg, &forcedReturn);
+    masm.mov(lr, pc);
+
+    masm.bind(&forcedReturn);
+    masm.loadValue(Address(r11, BaselineFrame::reverseOffsetOfReturnValue()),
+                   JSReturnOperand);
+    masm.mov(r11, sp);
+    masm.pop(r11);
+
+    // Before returning, if profiling is turned on, make sure that lastProfilingFrame
+    // is set to the correct caller frame.
+    {
+        Label skipProfilingInstrumentation;
+        AbsoluteAddress addressOfEnabled(cx->runtime()->spsProfiler.addressOfEnabled());
+        masm.branch32(Assembler::Equal, addressOfEnabled, Imm32(0), &skipProfilingInstrumentation);
+        masm.profilerExitFrame();
+        masm.bind(&skipProfilingInstrumentation);
+    }
+
+    masm.ret();
+
+    Linker linker(masm);
+    AutoFlushICache afc("DebugTrapHandler");
+    JitCode* codeDbg = linker.newCode<NoGC>(cx, OTHER_CODE);
+
+#ifdef JS_ION_PERF
+    writePerfSpewerJitCodeProfile(codeDbg, "DebugTrapHandler");
+#endif
+
+    return codeDbg;
+}
+
+JitCode*
+JitRuntime::generateExceptionTailStub(JSContext* cx, void* handler)
+{
+    MacroAssembler masm;
+
+    masm.handleFailureWithHandlerTail(handler);
+
+    Linker linker(masm);
+    AutoFlushICache afc("ExceptionTailStub");
+    JitCode* code = linker.newCode<NoGC>(cx, OTHER_CODE);
+
+#ifdef JS_ION_PERF
+    writePerfSpewerJitCodeProfile(code, "ExceptionTailStub");
+#endif
+
+    return code;
+}
+
+JitCode*
+JitRuntime::generateBailoutTailStub(JSContext* cx)
+{
+    MacroAssembler masm;
+
+    masm.generateBailoutTail(r1, r2);
+
+    Linker linker(masm);
+    AutoFlushICache afc("BailoutTailStub");
+    JitCode* code = linker.newCode<NoGC>(cx, OTHER_CODE);
+
+#ifdef JS_ION_PERF
+    writePerfSpewerJitCodeProfile(code, "BailoutTailStub");
+#endif
+
+    return code;
+}
+
+JitCode*
+JitRuntime::generateProfilerExitFrameTailStub(JSContext* cx)
+{
+    MacroAssembler masm;
+
+    Register scratch1 = r5;
+    Register scratch2 = r6;
+    Register scratch3 = r7;
+    Register scratch4 = r8;
+
+    //
+    // The code generated below expects that the current stack pointer points
+    // to an Ion or Baseline frame, at the state it would be immediately
+    // before a ret().  Thus, after this stub's business is done, it executes
+    // a ret() and returns directly to the caller script, on behalf of the
+    // callee script that jumped to this code.
+    //
+    // Thus the expected stack is:
+    //
+    //                                   StackPointer ----+
+    //                                                    v
+    // ..., ActualArgc, CalleeToken, Descriptor, ReturnAddr
+    // MEM-HI                                       MEM-LOW
+    //
+    //
+    // The generated jitcode is responsible for overwriting the
+    // jitActivation->lastProfilingFrame field with a pointer to the previous
+    // Ion or Baseline jit-frame that was pushed before this one. It is also
+    // responsible for overwriting jitActivation->lastProfilingCallSite with
+    // the return address into that frame.  The frame could either be an
+    // immediate "caller" frame, or it could be a frame in a previous
+    // JitActivation (if the current frame was entered from C++, and the C++
+    // was entered by some caller jit-frame further down the stack).
+    //
+    // So this jitcode is responsible for "walking up" the jit stack, finding
+    // the previous Ion or Baseline JS frame, and storing its address and the
+    // return address into the appropriate fields on the current jitActivation.
+    //
+    // There are a fixed number of different path types that can lead to the
+    // current frame, which is either a baseline or ion frame:
+    //
+    // <Baseline-Or-Ion>
+    // ^
+    // |
+    // ^--- Ion
+    // |
+    // ^--- Baseline Stub <---- Baseline
+    // |
+    // ^--- Argument Rectifier
+    // |    ^
+    // |    |
+    // |    ^--- Ion
+    // |    |
+    // |    ^--- Baseline Stub <---- Baseline
+    // |
+    // ^--- Entry Frame (From C++)
+    //
+    Register actReg = scratch4;
+    AbsoluteAddress activationAddr(GetJitContext()->runtime->addressOfProfilingActivation());
+    masm.loadPtr(activationAddr, actReg);
+
+    Address lastProfilingFrame(actReg, JitActivation::offsetOfLastProfilingFrame());
+    Address lastProfilingCallSite(actReg, JitActivation::offsetOfLastProfilingCallSite());
+
+#ifdef DEBUG
+    // Ensure that frame we are exiting is current lastProfilingFrame
+    {
+        masm.loadPtr(lastProfilingFrame, scratch1);
+        Label checkOk;
+        masm.branchPtr(Assembler::Equal, scratch1, ImmWord(0), &checkOk);
+        masm.branchPtr(Assembler::Equal, StackPointer, scratch1, &checkOk);
+        masm.assumeUnreachable(
+            "Mismatch between stored lastProfilingFrame and current stack pointer.");
+        masm.bind(&checkOk);
+    }
+#endif
+
+    // Load the frame descriptor into |scratch1|, figure out what to do depending on its type.
+    masm.loadPtr(Address(StackPointer, JitFrameLayout::offsetOfDescriptor()), scratch1);
+
+    // Going into the conditionals, we will have:
+    //      FrameDescriptor.size in scratch1
+    //      FrameDescriptor.type in scratch2
+    {
+        ScratchRegisterScope asmScratch(masm);
+        masm.ma_and(Imm32((1 << FRAMETYPE_BITS) - 1), scratch1, scratch2, asmScratch);
+    }
+    masm.rshiftPtr(Imm32(FRAMESIZE_SHIFT), scratch1);
+
+    // Handling of each case is dependent on FrameDescriptor.type
+    Label handle_IonJS;
+    Label handle_BaselineStub;
+    Label handle_Rectifier;
+    Label handle_IonAccessorIC;
+    Label handle_Entry;
+    Label end;
+
+    masm.branch32(Assembler::Equal, scratch2, Imm32(JitFrame_IonJS), &handle_IonJS);
+    masm.branch32(Assembler::Equal, scratch2, Imm32(JitFrame_BaselineJS), &handle_IonJS);
+    masm.branch32(Assembler::Equal, scratch2, Imm32(JitFrame_BaselineStub), &handle_BaselineStub);
+    masm.branch32(Assembler::Equal, scratch2, Imm32(JitFrame_Rectifier), &handle_Rectifier);
+    masm.branch32(Assembler::Equal, scratch2, Imm32(JitFrame_IonAccessorIC), &handle_IonAccessorIC);
+    masm.branch32(Assembler::Equal, scratch2, Imm32(JitFrame_Entry), &handle_Entry);
+
+    masm.assumeUnreachable("Invalid caller frame type when exiting from Ion frame.");
+
+    //
+    // JitFrame_IonJS
+    //
+    // Stack layout:
+    //                  ...
+    //                  Ion-Descriptor
+    //     Prev-FP ---> Ion-ReturnAddr
+    //                  ... previous frame data ... |- Descriptor.Size
+    //                  ... arguments ...           |
+    //                  ActualArgc          |
+    //                  CalleeToken         |- JitFrameLayout::Size()
+    //                  Descriptor          |
+    //        FP -----> ReturnAddr          |
+    //
+    masm.bind(&handle_IonJS);
+    {
+        // |scratch1| contains Descriptor.size
+
+        // returning directly to an IonJS frame.  Store return addr to frame
+        // in lastProfilingCallSite.
+        masm.loadPtr(Address(StackPointer, JitFrameLayout::offsetOfReturnAddress()), scratch2);
+        masm.storePtr(scratch2, lastProfilingCallSite);
+
+        // Store return frame in lastProfilingFrame.
+        // scratch2 := StackPointer + Descriptor.size*1 + JitFrameLayout::Size();
+        masm.ma_add(StackPointer, scratch1, scratch2);
+        masm.as_add(scratch2, scratch2, Imm8(JitFrameLayout::Size()));
+        masm.storePtr(scratch2, lastProfilingFrame);
+        masm.ret();
+    }
+
+    //
+    // JitFrame_BaselineStub
+    //
+    // Look past the stub and store the frame pointer to
+    // the baselineJS frame prior to it.
+    //
+    // Stack layout:
+    //              ...
+    //              BL-Descriptor
+    // Prev-FP ---> BL-ReturnAddr
+    //      +-----> BL-PrevFramePointer
+    //      |       ... BL-FrameData ...
+    //      |       BLStub-Descriptor
+    //      |       BLStub-ReturnAddr
+    //      |       BLStub-StubPointer          |
+    //      +------ BLStub-SavedFramePointer    |- Descriptor.Size
+    //              ... arguments ...           |
+    //              ActualArgc          |
+    //              CalleeToken         |- JitFrameLayout::Size()
+    //              Descriptor          |
+    //    FP -----> ReturnAddr          |
+    //
+    // We take advantage of the fact that the stub frame saves the frame
+    // pointer pointing to the baseline frame, so a bunch of calculation can
+    // be avoided.
+    //
+    masm.bind(&handle_BaselineStub);
+    {
+        masm.ma_add(StackPointer, scratch1, scratch3);
+        Address stubFrameReturnAddr(scratch3,
+                                    JitFrameLayout::Size() +
+                                    BaselineStubFrameLayout::offsetOfReturnAddress());
+        masm.loadPtr(stubFrameReturnAddr, scratch2);
+        masm.storePtr(scratch2, lastProfilingCallSite);
+
+        Address stubFrameSavedFramePtr(scratch3,
+                                       JitFrameLayout::Size() - (2 * sizeof(void*)));
+        masm.loadPtr(stubFrameSavedFramePtr, scratch2);
+        masm.addPtr(Imm32(sizeof(void*)), scratch2); // Skip past BL-PrevFramePtr
+        masm.storePtr(scratch2, lastProfilingFrame);
+        masm.ret();
+    }
+
+
+    //
+    // JitFrame_Rectifier
+    //
+    // The rectifier frame can be preceded by either an IonJS or a
+    // BaselineStub frame.
+    //
+    // Stack layout if caller of rectifier was Ion:
+    //
+    //              Ion-Descriptor
+    //              Ion-ReturnAddr
+    //              ... ion frame data ... |- Rect-Descriptor.Size
+    //              < COMMON LAYOUT >
+    //
+    // Stack layout if caller of rectifier was Baseline:
+    //
+    //              BL-Descriptor
+    // Prev-FP ---> BL-ReturnAddr
+    //      +-----> BL-SavedFramePointer
+    //      |       ... baseline frame data ...
+    //      |       BLStub-Descriptor
+    //      |       BLStub-ReturnAddr
+    //      |       BLStub-StubPointer          |
+    //      +------ BLStub-SavedFramePointer    |- Rect-Descriptor.Size
+    //              ... args to rectifier ...   |
+    //              < COMMON LAYOUT >
+    //
+    // Common stack layout:
+    //
+    //              ActualArgc          |
+    //              CalleeToken         |- IonRectitiferFrameLayout::Size()
+    //              Rect-Descriptor     |
+    //              Rect-ReturnAddr     |
+    //              ... rectifier data & args ... |- Descriptor.Size
+    //              ActualArgc      |
+    //              CalleeToken     |- JitFrameLayout::Size()
+    //              Descriptor      |
+    //    FP -----> ReturnAddr      |
+    //
+    masm.bind(&handle_Rectifier);
+    {
+        // scratch2 := StackPointer + Descriptor.size*1 + JitFrameLayout::Size();
+        masm.ma_add(StackPointer, scratch1, scratch2);
+        masm.add32(Imm32(JitFrameLayout::Size()), scratch2);
+        masm.loadPtr(Address(scratch2, RectifierFrameLayout::offsetOfDescriptor()), scratch3);
+        masm.ma_lsr(Imm32(FRAMESIZE_SHIFT), scratch3, scratch1);
+        masm.and32(Imm32((1 << FRAMETYPE_BITS) - 1), scratch3);
+
+        // Now |scratch1| contains Rect-Descriptor.Size
+        // and |scratch2| points to Rectifier frame
+        // and |scratch3| contains Rect-Descriptor.Type
+
+        // Check for either Ion or BaselineStub frame.
+        Label handle_Rectifier_BaselineStub;
+        masm.branch32(Assembler::NotEqual, scratch3, Imm32(JitFrame_IonJS),
+                      &handle_Rectifier_BaselineStub);
+
+        // Handle Rectifier <- IonJS
+        // scratch3 := RectFrame[ReturnAddr]
+        masm.loadPtr(Address(scratch2, RectifierFrameLayout::offsetOfReturnAddress()), scratch3);
+        masm.storePtr(scratch3, lastProfilingCallSite);
+
+        // scratch3 := RectFrame + Rect-Descriptor.Size + RectifierFrameLayout::Size()
+        masm.ma_add(scratch2, scratch1, scratch3);
+        masm.add32(Imm32(RectifierFrameLayout::Size()), scratch3);
+        masm.storePtr(scratch3, lastProfilingFrame);
+        masm.ret();
+
+        // Handle Rectifier <- BaselineStub <- BaselineJS
+        masm.bind(&handle_Rectifier_BaselineStub);
+#ifdef DEBUG
+        {
+            Label checkOk;
+            masm.branch32(Assembler::Equal, scratch3, Imm32(JitFrame_BaselineStub), &checkOk);
+            masm.assumeUnreachable("Unrecognized frame preceding baselineStub.");
+            masm.bind(&checkOk);
+        }
+#endif
+        masm.ma_add(scratch2, scratch1, scratch3);
+        Address stubFrameReturnAddr(scratch3, RectifierFrameLayout::Size() +
+                                              BaselineStubFrameLayout::offsetOfReturnAddress());
+        masm.loadPtr(stubFrameReturnAddr, scratch2);
+        masm.storePtr(scratch2, lastProfilingCallSite);
+
+        Address stubFrameSavedFramePtr(scratch3,
+                                       RectifierFrameLayout::Size() - (2 * sizeof(void*)));
+        masm.loadPtr(stubFrameSavedFramePtr, scratch2);
+        masm.addPtr(Imm32(sizeof(void*)), scratch2);
+        masm.storePtr(scratch2, lastProfilingFrame);
+        masm.ret();
+    }
+
+    // JitFrame_IonAccessorIC
+    //
+    // The caller is always an IonJS frame.
+    //
+    //              Ion-Descriptor
+    //              Ion-ReturnAddr
+    //              ... ion frame data ... |- AccFrame-Descriptor.Size
+    //              StubCode             |
+    //              AccFrame-Descriptor  |- IonAccessorICFrameLayout::Size()
+    //              AccFrame-ReturnAddr  |
+    //              ... accessor frame data & args ... |- Descriptor.Size
+    //              ActualArgc      |
+    //              CalleeToken     |- JitFrameLayout::Size()
+    //              Descriptor      |
+    //    FP -----> ReturnAddr      |
+    masm.bind(&handle_IonAccessorIC);
+    {
+        // scratch2 := StackPointer + Descriptor.size + JitFrameLayout::Size()
+        masm.ma_add(StackPointer, scratch1, scratch2);
+        masm.addPtr(Imm32(JitFrameLayout::Size()), scratch2);
+
+        // scratch3 := AccFrame-Descriptor.Size
+        masm.loadPtr(Address(scratch2, IonAccessorICFrameLayout::offsetOfDescriptor()), scratch3);
+#ifdef DEBUG
+        // Assert previous frame is an IonJS frame.
+        masm.movePtr(scratch3, scratch1);
+        masm.and32(Imm32((1 << FRAMETYPE_BITS) - 1), scratch1);
+        {
+            Label checkOk;
+            masm.branch32(Assembler::Equal, scratch1, Imm32(JitFrame_IonJS), &checkOk);
+            masm.assumeUnreachable("IonAccessorIC frame must be preceded by IonJS frame");
+            masm.bind(&checkOk);
+        }
+#endif
+        masm.rshiftPtr(Imm32(FRAMESIZE_SHIFT), scratch3);
+
+        // lastProfilingCallSite := AccFrame-ReturnAddr
+        masm.loadPtr(Address(scratch2, IonAccessorICFrameLayout::offsetOfReturnAddress()), scratch1);
+        masm.storePtr(scratch1, lastProfilingCallSite);
+
+        // lastProfilingFrame := AccessorFrame + AccFrame-Descriptor.Size +
+        //                       IonAccessorICFrameLayout::Size()
+        masm.ma_add(scratch2, scratch3, scratch1);
+        masm.addPtr(Imm32(IonAccessorICFrameLayout::Size()), scratch1);
+        masm.storePtr(scratch1, lastProfilingFrame);
+        masm.ret();
+    }
+
+    //
+    // JitFrame_Entry
+    //
+    // If at an entry frame, store null into both fields.
+    //
+    masm.bind(&handle_Entry);
+    {
+        masm.movePtr(ImmPtr(nullptr), scratch1);
+        masm.storePtr(scratch1, lastProfilingCallSite);
+        masm.storePtr(scratch1, lastProfilingFrame);
+        masm.ret();
+    }
+
+    Linker linker(masm);
+    AutoFlushICache afc("ProfilerExitFrameTailStub");
+    JitCode* code = linker.newCode<NoGC>(cx, OTHER_CODE);
+
+#ifdef JS_ION_PERF
+    writePerfSpewerJitCodeProfile(code, "ProfilerExitFrameStub");
+#endif
+
+    return code;
+}
diff --git a/js/src/jit/arm/disasm/Constants-arm.cpp b/js/src/jit/arm/disasm/Constants-arm.cpp
new file mode 100644
index 0000000000..2201a85e7e
--- /dev/null
+++ b/js/src/jit/arm/disasm/Constants-arm.cpp
@@ -0,0 +1,144 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ */
+// Copyright 2009 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "jit/arm/disasm/Constants-arm.h"
+
+#ifdef JS_DISASM_ARM
+
+namespace js {
+namespace jit {
+namespace disasm {
+
+double
+Instruction::DoubleImmedVmov() const
+{
+    // Reconstruct a double from the immediate encoded in the vmov instruction.
+    //
+    //   instruction: [xxxxxxxx,xxxxabcd,xxxxxxxx,xxxxefgh]
+    //   double: [aBbbbbbb,bbcdefgh,00000000,00000000,
+    //            00000000,00000000,00000000,00000000]
+    //
+    // where B = ~b. Only the high 16 bits are affected.
+    uint64_t high16;
+    high16  = (Bits(17, 16) << 4) | Bits(3, 0);   // xxxxxxxx,xxcdefgh.
+    high16 |= (0xff * Bit(18)) << 6;              // xxbbbbbb,bbxxxxxx.
+    high16 |= (Bit(18) ^ 1) << 14;                // xBxxxxxx,xxxxxxxx.
+    high16 |= Bit(19) << 15;                      // axxxxxxx,xxxxxxxx.
+
+    uint64_t imm = high16 << 48;
+    double d;
+    memcpy(&d, &imm, 8);
+    return d;
+}
+
+
+// These register names are defined in a way to match the native disassembler
+// formatting. See for example the command "objdump -d <binary file>".
+const char* Registers::names_[kNumRegisters] = {
+    "r0", "r1", "r2", "r3", "r4", "r5", "r6", "r7",
+    "r8", "r9", "r10", "fp", "ip", "sp", "lr", "pc",
+};
+
+
+// List of alias names which can be used when referring to ARM registers.
+const Registers::RegisterAlias Registers::aliases_[] = {
+    {10, "sl"},
+    {11, "r11"},
+    {12, "r12"},
+    {13, "r13"},
+    {14, "r14"},
+    {15, "r15"},
+    {kNoRegister, NULL}
+};
+
+
+const char*
+Registers::Name(int reg)
+{
+    const char* result;
+    if ((0 <= reg) && (reg < kNumRegisters)) {
+        result = names_[reg];
+    } else {
+        result = "noreg";
+    }
+    return result;
+}
+
+
+// Support for VFP registers s0 to s31 (d0 to d15) and d16-d31.
+// Note that "sN:sM" is the same as "dN/2" up to d15.
+// These register names are defined in a way to match the native disassembler
+// formatting. See for example the command "objdump -d <binary file>".
+const char* VFPRegisters::names_[kNumVFPRegisters] = {
+    "s0", "s1", "s2", "s3", "s4", "s5", "s6", "s7",
+    "s8", "s9", "s10", "s11", "s12", "s13", "s14", "s15",
+    "s16", "s17", "s18", "s19", "s20", "s21", "s22", "s23",
+    "s24", "s25", "s26", "s27", "s28", "s29", "s30", "s31",
+    "d0", "d1", "d2", "d3", "d4", "d5", "d6", "d7",
+    "d8", "d9", "d10", "d11", "d12", "d13", "d14", "d15",
+    "d16", "d17", "d18", "d19", "d20", "d21", "d22", "d23",
+    "d24", "d25", "d26", "d27", "d28", "d29", "d30", "d31"
+};
+
+
+const char*
+VFPRegisters::Name(int reg, bool is_double)
+{
+    MOZ_ASSERT((0 <= reg) && (reg < kNumVFPRegisters));
+    return names_[reg + (is_double ? kNumVFPSingleRegisters : 0)];
+}
+
+
+int
+VFPRegisters::Number(const char* name, bool* is_double)
+{
+    for (int i = 0; i < kNumVFPRegisters; i++) {
+        if (strcmp(names_[i], name) == 0) {
+            if (i < kNumVFPSingleRegisters) {
+                *is_double = false;
+                return i;
+            } else {
+                *is_double = true;
+                return i - kNumVFPSingleRegisters;
+            }
+        }
+    }
+
+    // No register with the requested name found.
+    return kNoRegister;
+}
+
+
+int
+Registers::Number(const char* name)
+{
+    // Look through the canonical names.
+    for (int i = 0; i < kNumRegisters; i++) {
+        if (strcmp(names_[i], name) == 0) {
+            return i;
+        }
+    }
+
+    // Look through the alias names.
+    int i = 0;
+    while (aliases_[i].reg != kNoRegister) {
+        if (strcmp(aliases_[i].name, name) == 0) {
+            return aliases_[i].reg;
+        }
+        i++;
+    }
+
+    // No register with the requested name found.
+    return kNoRegister;
+}
+
+
+}  // namespace disasm
+}  // namespace jit
+}  // namespace js
+
+#endif // JS_DISASM_ARM
diff --git a/js/src/jit/arm/disasm/Constants-arm.h b/js/src/jit/arm/disasm/Constants-arm.h
new file mode 100644
index 0000000000..de63f39dc3
--- /dev/null
+++ b/js/src/jit/arm/disasm/Constants-arm.h
@@ -0,0 +1,745 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ */
+// Copyright 2011 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef jit_arm_disasm_Constants_arm_h
+#define jit_arm_disasm_Constants_arm_h
+
+#ifdef JS_DISASM_ARM
+
+#include "mozilla/Assertions.h"
+#include "mozilla/Types.h"
+
+#include <string.h>
+
+namespace js {
+namespace jit {
+namespace disasm {
+
+// Constant pool marker.
+// Use UDF, the permanently undefined instruction.
+const int kConstantPoolMarkerMask = 0xfff000f0;
+const int kConstantPoolMarker = 0xe7f000f0;
+const int kConstantPoolLengthMaxMask = 0xffff;
+
+inline int
+EncodeConstantPoolLength(int length)
+{
+    MOZ_ASSERT((length & kConstantPoolLengthMaxMask) == length);
+    return ((length & 0xfff0) << 4) | (length & 0xf);
+}
+
+inline int
+DecodeConstantPoolLength(int instr)
+{
+    MOZ_ASSERT((instr & kConstantPoolMarkerMask) == kConstantPoolMarker);
+    return ((instr >> 4) & 0xfff0) | (instr & 0xf);
+}
+
+// Used in code age prologue - ldr(pc, MemOperand(pc, -4))
+const int kCodeAgeJumpInstruction = 0xe51ff004;
+
+// Number of registers in normal ARM mode.
+const int kNumRegisters = 16;
+
+// VFP support.
+const int kNumVFPSingleRegisters = 32;
+const int kNumVFPDoubleRegisters = 32;
+const int kNumVFPRegisters = kNumVFPSingleRegisters + kNumVFPDoubleRegisters;
+
+// PC is register 15.
+const int kPCRegister = 15;
+const int kNoRegister = -1;
+
+// -----------------------------------------------------------------------------
+// Conditions.
+
+// Defines constants and accessor classes to assemble, disassemble and
+// simulate ARM instructions.
+//
+// Section references in the code refer to the "ARM Architecture Reference
+// Manual" from July 2005 (available at http://www.arm.com/miscPDFs/14128.pdf)
+//
+// Constants for specific fields are defined in their respective named enums.
+// General constants are in an anonymous enum in class Instr.
+
+// Values for the condition field as defined in section A3.2
+enum Condition {
+    kNoCondition = -1,
+
+    eq =  0 << 28,                 // Z set            Equal.
+    ne =  1 << 28,                 // Z clear          Not equal.
+    cs =  2 << 28,                 // C set            Unsigned higher or same.
+    cc =  3 << 28,                 // C clear          Unsigned lower.
+    mi =  4 << 28,                 // N set            Negative.
+    pl =  5 << 28,                 // N clear          Positive or zero.
+    vs =  6 << 28,                 // V set            Overflow.
+    vc =  7 << 28,                 // V clear          No overflow.
+    hi =  8 << 28,                 // C set, Z clear   Unsigned higher.
+    ls =  9 << 28,                 // C clear or Z set Unsigned lower or same.
+    ge = 10 << 28,                 // N == V           Greater or equal.
+    lt = 11 << 28,                 // N != V           Less than.
+    gt = 12 << 28,                 // Z clear, N == V  Greater than.
+    le = 13 << 28,                 // Z set or N != V  Less then or equal
+    al = 14 << 28,                 //                  Always.
+
+    kSpecialCondition = 15 << 28,  // Special condition (refer to section A3.2.1).
+    kNumberOfConditions = 16,
+
+    // Aliases.
+    hs = cs,                       // C set            Unsigned higher or same.
+    lo = cc                        // C clear          Unsigned lower.
+};
+
+
+inline Condition
+NegateCondition(Condition cond)
+{
+    MOZ_ASSERT(cond != al);
+    return static_cast<Condition>(cond ^ ne);
+}
+
+
+// Commute a condition such that {a cond b == b cond' a}.
+inline Condition
+CommuteCondition(Condition cond)
+{
+    switch (cond) {
+      case lo:
+        return hi;
+      case hi:
+        return lo;
+      case hs:
+        return ls;
+      case ls:
+        return hs;
+      case lt:
+        return gt;
+      case gt:
+        return lt;
+      case ge:
+        return le;
+      case le:
+        return ge;
+      default:
+        return cond;
+    }
+}
+
+
+// -----------------------------------------------------------------------------
+// Instructions encoding.
+
+// Instr is merely used by the Assembler to distinguish 32bit integers
+// representing instructions from usual 32 bit values.
+// Instruction objects are pointers to 32bit values, and provide methods to
+// access the various ISA fields.
+typedef int32_t Instr;
+
+
+// Opcodes for Data-processing instructions (instructions with a type 0 and 1)
+// as defined in section A3.4
+enum Opcode {
+    AND =  0 << 21,  // Logical AND.
+    EOR =  1 << 21,  // Logical Exclusive OR.
+    SUB =  2 << 21,  // Subtract.
+    RSB =  3 << 21,  // Reverse Subtract.
+    ADD =  4 << 21,  // Add.
+    ADC =  5 << 21,  // Add with Carry.
+    SBC =  6 << 21,  // Subtract with Carry.
+    RSC =  7 << 21,  // Reverse Subtract with Carry.
+    TST =  8 << 21,  // Test.
+    TEQ =  9 << 21,  // Test Equivalence.
+    CMP = 10 << 21,  // Compare.
+    CMN = 11 << 21,  // Compare Negated.
+    ORR = 12 << 21,  // Logical (inclusive) OR.
+    MOV = 13 << 21,  // Move.
+    BIC = 14 << 21,  // Bit Clear.
+    MVN = 15 << 21   // Move Not.
+};
+
+
+// The bits for bit 7-4 for some type 0 miscellaneous instructions.
+enum MiscInstructionsBits74 {
+    // With bits 22-21 01.
+    BX   =  1 << 4,
+    BXJ  =  2 << 4,
+    BLX  =  3 << 4,
+    BKPT =  7 << 4,
+
+    // With bits 22-21 11.
+    CLZ  =  1 << 4
+};
+
+// Load and store exclusive instructions.
+
+// Bit positions.
+enum {
+    ExclusiveOpHi = 24,         // Hi bit of opcode field
+    ExclusiveOpLo = 23,         // Lo bit of opcode field
+    ExclusiveSizeHi = 22,       // Hi bit of operand size field
+    ExclusiveSizeLo = 21,       // Lo bit of operand size field
+    ExclusiveLoad = 20          // Bit indicating load
+};
+
+// Opcode bits for exclusive instructions.
+enum {
+    ExclusiveOpcode = 3
+};
+
+// Operand size, Bits(ExclusiveSizeHi,ExclusiveSizeLo).
+enum {
+    ExclusiveWord = 0,
+    ExclusiveDouble = 1,
+    ExclusiveByte = 2,
+    ExclusiveHalf = 3
+};
+
+// Instruction encoding bits and masks.
+enum {
+    H = 1 << 5,   // Halfword (or byte).
+    S6 = 1 << 6,  // Signed (or unsigned).
+    L = 1 << 20,  // Load (or store).
+    S = 1 << 20,  // Set condition code (or leave unchanged).
+    W = 1 << 21,  // Writeback base register (or leave unchanged).
+    A = 1 << 21,  // Accumulate in multiply instruction (or not).
+    B = 1 << 22,  // Unsigned byte (or word).
+    N = 1 << 22,  // Long (or short).
+    U = 1 << 23,  // Positive (or negative) offset/index.
+    P = 1 << 24,  // Offset/pre-indexed addressing (or post-indexed addressing).
+    I = 1 << 25,  // Immediate shifter operand (or not).
+    B0 = 1 << 0,
+    B4 = 1 << 4,
+    B5 = 1 << 5,
+    B6 = 1 << 6,
+    B7 = 1 << 7,
+    B8 = 1 << 8,
+    B9 = 1 << 9,
+    B12 = 1 << 12,
+    B16 = 1 << 16,
+    B17 = 1 << 17,
+    B18 = 1 << 18,
+    B19 = 1 << 19,
+    B20 = 1 << 20,
+    B21 = 1 << 21,
+    B22 = 1 << 22,
+    B23 = 1 << 23,
+    B24 = 1 << 24,
+    B25 = 1 << 25,
+    B26 = 1 << 26,
+    B27 = 1 << 27,
+    B28 = 1 << 28,
+
+    // Instruction bit masks.
+    kCondMask = 15 << 28,
+    kALUMask = 0x6f << 21,
+    kRdMask = 15 << 12,  // In str instruction.
+    kCoprocessorMask = 15 << 8,
+    kOpCodeMask = 15 << 21,  // In data-processing instructions.
+    kImm24Mask = (1 << 24) - 1,
+    kImm16Mask = (1 << 16) - 1,
+    kImm8Mask = (1 << 8) - 1,
+    kOff12Mask = (1 << 12) - 1,
+    kOff8Mask = (1 << 8) - 1
+};
+
+
+// -----------------------------------------------------------------------------
+// Addressing modes and instruction variants.
+
+// Condition code updating mode.
+enum SBit {
+    SetCC   = 1 << 20,  // Set condition code.
+    LeaveCC = 0 << 20   // Leave condition code unchanged.
+};
+
+
+// Status register selection.
+enum SRegister {
+    CPSR = 0 << 22,
+    SPSR = 1 << 22
+};
+
+
+// Shifter types for Data-processing operands as defined in section A5.1.2.
+enum ShiftOp {
+    LSL = 0 << 5,   // Logical shift left.
+    LSR = 1 << 5,   // Logical shift right.
+    ASR = 2 << 5,   // Arithmetic shift right.
+    ROR = 3 << 5,   // Rotate right.
+
+    // RRX is encoded as ROR with shift_imm == 0.
+    // Use a special code to make the distinction. The RRX ShiftOp is only used
+    // as an argument, and will never actually be encoded. The Assembler will
+    // detect it and emit the correct ROR shift operand with shift_imm == 0.
+    RRX = -1,
+    kNumberOfShifts = 4
+};
+
+
+// Status register fields.
+enum SRegisterField {
+    CPSR_c = CPSR | 1 << 16,
+    CPSR_x = CPSR | 1 << 17,
+    CPSR_s = CPSR | 1 << 18,
+    CPSR_f = CPSR | 1 << 19,
+    SPSR_c = SPSR | 1 << 16,
+    SPSR_x = SPSR | 1 << 17,
+    SPSR_s = SPSR | 1 << 18,
+    SPSR_f = SPSR | 1 << 19
+};
+
+// Status register field mask (or'ed SRegisterField enum values).
+typedef uint32_t SRegisterFieldMask;
+
+
+// Memory operand addressing mode.
+enum AddrMode {
+    // Bit encoding P U W.
+    Offset       = (8|4|0) << 21,  // Offset (without writeback to base).
+    PreIndex     = (8|4|1) << 21,  // Pre-indexed addressing with writeback.
+    PostIndex    = (0|4|0) << 21,  // Post-indexed addressing with writeback.
+    NegOffset    = (8|0|0) << 21,  // Negative offset (without writeback to base).
+    NegPreIndex  = (8|0|1) << 21,  // Negative pre-indexed with writeback.
+    NegPostIndex = (0|0|0) << 21   // Negative post-indexed with writeback.
+};
+
+
+// Load/store multiple addressing mode.
+enum BlockAddrMode {
+    // Bit encoding P U W .
+    da           = (0|0|0) << 21,  // Decrement after.
+    ia           = (0|4|0) << 21,  // Increment after.
+    db           = (8|0|0) << 21,  // Decrement before.
+    ib           = (8|4|0) << 21,  // Increment before.
+    da_w         = (0|0|1) << 21,  // Decrement after with writeback to base.
+    ia_w         = (0|4|1) << 21,  // Increment after with writeback to base.
+    db_w         = (8|0|1) << 21,  // Decrement before with writeback to base.
+    ib_w         = (8|4|1) << 21,  // Increment before with writeback to base.
+
+    // Alias modes for comparison when writeback does not matter.
+    da_x         = (0|0|0) << 21,  // Decrement after.
+    ia_x         = (0|4|0) << 21,  // Increment after.
+    db_x         = (8|0|0) << 21,  // Decrement before.
+    ib_x         = (8|4|0) << 21,  // Increment before.
+
+    kBlockAddrModeMask = (8|4|1) << 21
+};
+
+
+// Coprocessor load/store operand size.
+enum LFlag {
+    Long  = 1 << 22,  // Long load/store coprocessor.
+    Short = 0 << 22   // Short load/store coprocessor.
+};
+
+
+// NEON data type
+enum NeonDataType {
+    NeonS8 = 0x1,   // U = 0, imm3 = 0b001
+    NeonS16 = 0x2,  // U = 0, imm3 = 0b010
+    NeonS32 = 0x4,  // U = 0, imm3 = 0b100
+    NeonU8 = 1 << 24 | 0x1,   // U = 1, imm3 = 0b001
+    NeonU16 = 1 << 24 | 0x2,  // U = 1, imm3 = 0b010
+    NeonU32 = 1 << 24 | 0x4,   // U = 1, imm3 = 0b100
+    NeonDataTypeSizeMask = 0x7,
+    NeonDataTypeUMask = 1 << 24
+};
+
+enum NeonListType {
+    nlt_1 = 0x7,
+    nlt_2 = 0xA,
+    nlt_3 = 0x6,
+    nlt_4 = 0x2
+};
+
+enum NeonSize {
+    Neon8 = 0x0,
+    Neon16 = 0x1,
+    Neon32 = 0x2,
+    Neon64 = 0x3
+};
+
+// -----------------------------------------------------------------------------
+// Supervisor Call (svc) specific support.
+
+// Special Software Interrupt codes when used in the presence of the ARM
+// simulator.
+// svc (formerly swi) provides a 24bit immediate value. Use bits 22:0 for
+// standard SoftwareInterrupCode. Bit 23 is reserved for the stop feature.
+enum SoftwareInterruptCodes {
+    // transition to C code
+    kCallRtRedirected = 0x10,
+    // break point
+    kBreakpoint = 0x20,
+    // stop
+    kStopCode = 1 << 23
+};
+const uint32_t kStopCodeMask = kStopCode - 1;
+const uint32_t kMaxStopCode = kStopCode - 1;
+const int32_t  kDefaultStopCode = -1;
+
+
+// Type of VFP register. Determines register encoding.
+enum VFPRegPrecision {
+    kSinglePrecision = 0,
+    kDoublePrecision = 1
+};
+
+
+// VFP FPSCR constants.
+enum VFPConversionMode {
+    kFPSCRRounding = 0,
+    kDefaultRoundToZero = 1
+};
+
+// This mask does not include the "inexact" or "input denormal" cumulative
+// exceptions flags, because we usually don't want to check for it.
+const uint32_t kVFPExceptionMask = 0xf;
+const uint32_t kVFPInvalidOpExceptionBit = 1 << 0;
+const uint32_t kVFPOverflowExceptionBit = 1 << 2;
+const uint32_t kVFPUnderflowExceptionBit = 1 << 3;
+const uint32_t kVFPInexactExceptionBit = 1 << 4;
+const uint32_t kVFPFlushToZeroMask = 1 << 24;
+const uint32_t kVFPDefaultNaNModeControlBit = 1 << 25;
+
+const uint32_t kVFPNConditionFlagBit = 1 << 31;
+const uint32_t kVFPZConditionFlagBit = 1 << 30;
+const uint32_t kVFPCConditionFlagBit = 1 << 29;
+const uint32_t kVFPVConditionFlagBit = 1 << 28;
+
+
+// VFP rounding modes. See ARM DDI 0406B Page A2-29.
+enum VFPRoundingMode {
+    RN = 0 << 22,   // Round to Nearest.
+    RP = 1 << 22,   // Round towards Plus Infinity.
+    RM = 2 << 22,   // Round towards Minus Infinity.
+    RZ = 3 << 22,   // Round towards zero.
+
+    // Aliases.
+    kRoundToNearest = RN,
+    kRoundToPlusInf = RP,
+    kRoundToMinusInf = RM,
+    kRoundToZero = RZ
+};
+
+const uint32_t kVFPRoundingModeMask = 3 << 22;
+
+enum CheckForInexactConversion {
+    kCheckForInexactConversion,
+    kDontCheckForInexactConversion
+};
+
+// -----------------------------------------------------------------------------
+// Hints.
+
+// Branch hints are not used on the ARM.  They are defined so that they can
+// appear in shared function signatures, but will be ignored in ARM
+// implementations.
+enum Hint { no_hint };
+
+// Hints are not used on the arm.  Negating is trivial.
+inline Hint
+NegateHint(Hint ignored)
+{
+    return no_hint;
+}
+
+
+// -----------------------------------------------------------------------------
+// Instruction abstraction.
+
+// The class Instruction enables access to individual fields defined in the ARM
+// architecture instruction set encoding as described in figure A3-1.
+// Note that the Assembler uses typedef int32_t Instr.
+//
+// Example: Test whether the instruction at ptr does set the condition code
+// bits.
+//
+// bool InstructionSetsConditionCodes(byte* ptr) {
+//   Instruction* instr = Instruction::At(ptr);
+//   int type = instr->TypeValue();
+//   return ((type == 0) || (type == 1)) && instr->HasS();
+// }
+//
+class Instruction {
+  public:
+    enum {
+        kInstrSize = 4,
+        kInstrSizeLog2 = 2,
+        kPCReadOffset = 8
+    };
+
+    // Helper macro to define static accessors.
+    // We use the cast to char* trick to bypass the strict anti-aliasing rules.
+#define DECLARE_STATIC_TYPED_ACCESSOR(return_type, Name)        \
+    static inline return_type Name(Instr instr) {               \
+        char* temp = reinterpret_cast<char*>(&instr);           \
+        return reinterpret_cast<Instruction*>(temp)->Name();    \
+    }
+
+#define DECLARE_STATIC_ACCESSOR(Name) DECLARE_STATIC_TYPED_ACCESSOR(int, Name)
+
+    // Get the raw instruction bits.
+    inline Instr InstructionBits() const {
+        return *reinterpret_cast<const Instr*>(this);
+    }
+
+    // Set the raw instruction bits to value.
+    inline void SetInstructionBits(Instr value) {
+        *reinterpret_cast<Instr*>(this) = value;
+    }
+
+    // Read one particular bit out of the instruction bits.
+    inline int Bit(int nr) const {
+        return (InstructionBits() >> nr) & 1;
+    }
+
+    // Read a bit field's value out of the instruction bits.
+    inline int Bits(int hi, int lo) const {
+        return (InstructionBits() >> lo) & ((2 << (hi - lo)) - 1);
+    }
+
+    // Read a bit field out of the instruction bits.
+    inline int BitField(int hi, int lo) const {
+        return InstructionBits() & (((2 << (hi - lo)) - 1) << lo);
+    }
+
+    // Static support.
+
+    // Read one particular bit out of the instruction bits.
+    static inline int Bit(Instr instr, int nr) {
+        return (instr >> nr) & 1;
+    }
+
+    // Read the value of a bit field out of the instruction bits.
+    static inline int Bits(Instr instr, int hi, int lo) {
+        return (instr >> lo) & ((2 << (hi - lo)) - 1);
+    }
+
+
+    // Read a bit field out of the instruction bits.
+    static inline int BitField(Instr instr, int hi, int lo) {
+        return instr & (((2 << (hi - lo)) - 1) << lo);
+    }
+
+
+    // Accessors for the different named fields used in the ARM encoding.
+    // The naming of these accessor corresponds to figure A3-1.
+    //
+    // Two kind of accessors are declared:
+    // - <Name>Field() will return the raw field, i.e. the field's bits at their
+    //   original place in the instruction encoding.
+    //   e.g. if instr is the 'addgt r0, r1, r2' instruction, encoded as
+    //   0xC0810002 ConditionField(instr) will return 0xC0000000.
+    // - <Name>Value() will return the field value, shifted back to bit 0.
+    //   e.g. if instr is the 'addgt r0, r1, r2' instruction, encoded as
+    //   0xC0810002 ConditionField(instr) will return 0xC.
+
+
+    // Generally applicable fields
+    inline Condition ConditionValue() const {
+        return static_cast<Condition>(Bits(31, 28));
+    }
+    inline Condition ConditionField() const {
+        return static_cast<Condition>(BitField(31, 28));
+    }
+    DECLARE_STATIC_TYPED_ACCESSOR(Condition, ConditionValue);
+    DECLARE_STATIC_TYPED_ACCESSOR(Condition, ConditionField);
+
+    inline int TypeValue() const { return Bits(27, 25); }
+    inline int SpecialValue() const { return Bits(27, 23); }
+
+    inline int RnValue() const { return Bits(19, 16); }
+    DECLARE_STATIC_ACCESSOR(RnValue);
+    inline int RdValue() const { return Bits(15, 12); }
+    DECLARE_STATIC_ACCESSOR(RdValue);
+
+    inline int CoprocessorValue() const { return Bits(11, 8); }
+    // Support for VFP.
+    // Vn(19-16) | Vd(15-12) |  Vm(3-0)
+    inline int VnValue() const { return Bits(19, 16); }
+    inline int VmValue() const { return Bits(3, 0); }
+    inline int VdValue() const { return Bits(15, 12); }
+    inline int NValue() const { return Bit(7); }
+    inline int MValue() const { return Bit(5); }
+    inline int DValue() const { return Bit(22); }
+    inline int RtValue() const { return Bits(15, 12); }
+    inline int PValue() const { return Bit(24); }
+    inline int UValue() const { return Bit(23); }
+    inline int Opc1Value() const { return (Bit(23) << 2) | Bits(21, 20); }
+    inline int Opc2Value() const { return Bits(19, 16); }
+    inline int Opc3Value() const { return Bits(7, 6); }
+    inline int SzValue() const { return Bit(8); }
+    inline int VLValue() const { return Bit(20); }
+    inline int VCValue() const { return Bit(8); }
+    inline int VAValue() const { return Bits(23, 21); }
+    inline int VBValue() const { return Bits(6, 5); }
+    inline int VFPNRegValue(VFPRegPrecision pre) {
+        return VFPGlueRegValue(pre, 16, 7);
+    }
+    inline int VFPMRegValue(VFPRegPrecision pre) {
+        return VFPGlueRegValue(pre, 0, 5);
+    }
+    inline int VFPDRegValue(VFPRegPrecision pre) {
+        return VFPGlueRegValue(pre, 12, 22);
+    }
+
+    // Fields used in Data processing instructions
+    inline int OpcodeValue() const {
+        return static_cast<Opcode>(Bits(24, 21));
+    }
+    inline Opcode OpcodeField() const {
+        return static_cast<Opcode>(BitField(24, 21));
+    }
+    inline int SValue() const { return Bit(20); }
+    // with register
+    inline int RmValue() const { return Bits(3, 0); }
+    DECLARE_STATIC_ACCESSOR(RmValue);
+    inline int ShiftValue() const { return static_cast<ShiftOp>(Bits(6, 5)); }
+    inline ShiftOp ShiftField() const {
+        return static_cast<ShiftOp>(BitField(6, 5));
+    }
+    inline int RegShiftValue() const { return Bit(4); }
+    inline int RsValue() const { return Bits(11, 8); }
+    inline int ShiftAmountValue() const { return Bits(11, 7); }
+    // with immediate
+    inline int RotateValue() const { return Bits(11, 8); }
+    DECLARE_STATIC_ACCESSOR(RotateValue);
+    inline int Immed8Value() const { return Bits(7, 0); }
+    DECLARE_STATIC_ACCESSOR(Immed8Value);
+    inline int Immed4Value() const { return Bits(19, 16); }
+    inline int ImmedMovwMovtValue() const {
+        return Immed4Value() << 12 | Offset12Value(); }
+    DECLARE_STATIC_ACCESSOR(ImmedMovwMovtValue);
+
+    // Fields used in Load/Store instructions
+    inline int PUValue() const { return Bits(24, 23); }
+    inline int PUField() const { return BitField(24, 23); }
+    inline int  BValue() const { return Bit(22); }
+    inline int  WValue() const { return Bit(21); }
+    inline int  LValue() const { return Bit(20); }
+    // with register uses same fields as Data processing instructions above
+    // with immediate
+    inline int Offset12Value() const { return Bits(11, 0); }
+    // multiple
+    inline int RlistValue() const { return Bits(15, 0); }
+    // extra loads and stores
+    inline int SignValue() const { return Bit(6); }
+    inline int HValue() const { return Bit(5); }
+    inline int ImmedHValue() const { return Bits(11, 8); }
+    inline int ImmedLValue() const { return Bits(3, 0); }
+
+    // Fields used in Branch instructions
+    inline int LinkValue() const { return Bit(24); }
+    inline int SImmed24Value() const { return ((InstructionBits() << 8) >> 8); }
+
+    // Fields used in Software interrupt instructions
+    inline SoftwareInterruptCodes SvcValue() const {
+        return static_cast<SoftwareInterruptCodes>(Bits(23, 0));
+    }
+
+    // Test for special encodings of type 0 instructions (extra loads and stores,
+    // as well as multiplications).
+    inline bool IsSpecialType0() const { return (Bit(7) == 1) && (Bit(4) == 1); }
+
+    // Test for miscellaneous instructions encodings of type 0 instructions.
+    inline bool IsMiscType0() const { return (Bit(24) == 1)
+            && (Bit(23) == 0)
+            && (Bit(20) == 0)
+            && ((Bit(7) == 0)); }
+
+    // Test for a nop instruction, which falls under type 1.
+    inline bool IsNopType1() const { return Bits(24, 0) == 0x0120F000; }
+
+    // Test for a stop instruction.
+    inline bool IsStop() const {
+        return (TypeValue() == 7) && (Bit(24) == 1) && (SvcValue() >= kStopCode);
+    }
+
+    // Special accessors that test for existence of a value.
+    inline bool HasS()    const { return SValue() == 1; }
+    inline bool HasB()    const { return BValue() == 1; }
+    inline bool HasW()    const { return WValue() == 1; }
+    inline bool HasL()    const { return LValue() == 1; }
+    inline bool HasU()    const { return UValue() == 1; }
+    inline bool HasSign() const { return SignValue() == 1; }
+    inline bool HasH()    const { return HValue() == 1; }
+    inline bool HasLink() const { return LinkValue() == 1; }
+
+    // Decoding the double immediate in the vmov instruction.
+    double DoubleImmedVmov() const;
+
+    // Instructions are read of out a code stream. The only way to get a
+    // reference to an instruction is to convert a pointer. There is no way
+    // to allocate or create instances of class Instruction.
+    // Use the At(pc) function to create references to Instruction.
+    static Instruction* At(uint8_t* pc) {
+        return reinterpret_cast<Instruction*>(pc);
+    }
+
+
+  private:
+    // Join split register codes, depending on single or double precision.
+    // four_bit is the position of the least-significant bit of the four
+    // bit specifier. one_bit is the position of the additional single bit
+    // specifier.
+    inline int VFPGlueRegValue(VFPRegPrecision pre, int four_bit, int one_bit) {
+        if (pre == kSinglePrecision) {
+            return (Bits(four_bit + 3, four_bit) << 1) | Bit(one_bit);
+        }
+        return (Bit(one_bit) << 4) | Bits(four_bit + 3, four_bit);
+    }
+
+    // We need to prevent the creation of instances of class Instruction.
+    Instruction() = delete;
+    Instruction(const Instruction&) = delete;
+    void operator=(const Instruction&) = delete;
+};
+
+
+// Helper functions for converting between register numbers and names.
+class Registers {
+  public:
+    // Return the name of the register.
+    static const char* Name(int reg);
+
+    // Lookup the register number for the name provided.
+    static int Number(const char* name);
+
+    struct RegisterAlias {
+        int reg;
+        const char* name;
+    };
+
+  private:
+    static const char* names_[kNumRegisters];
+    static const RegisterAlias aliases_[];
+};
+
+// Helper functions for converting between VFP register numbers and names.
+class VFPRegisters {
+  public:
+    // Return the name of the register.
+    static const char* Name(int reg, bool is_double);
+
+    // Lookup the register number for the name provided.
+    // Set flag pointed by is_double to true if register
+    // is double-precision.
+    static int Number(const char* name, bool* is_double);
+
+  private:
+    static const char* names_[kNumVFPRegisters];
+};
+
+
+}  // namespace disasm
+}  // namespace jit
+}  // namespace js
+
+#endif // JS_DISASM_ARM
+
+#endif  // jit_arm_disasm_Constants_arm_h
diff --git a/js/src/jit/arm/disasm/Disasm-arm.cpp b/js/src/jit/arm/disasm/Disasm-arm.cpp
new file mode 100644
index 0000000000..8bd7bff0c2
--- /dev/null
+++ b/js/src/jit/arm/disasm/Disasm-arm.cpp
@@ -0,0 +1,2173 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ */
+// Copyright 2011 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// A Disassembler object is used to disassemble a block of code instruction by
+// instruction. The default implementation of the NameConverter object can be
+// overriden to modify register names or to do symbol lookup on addresses.
+//
+// The example below will disassemble a block of code and print it to stdout.
+//
+//   disasm::NameConverter converter;
+//   disasm::Disassembler d(converter);
+//   for (uint8_t* pc = begin; pc < end;) {
+//     disasm::EmbeddedVector<char, disasm::ReasonableBufferSize> buffer;
+//     uint8_t* prev_pc = pc;
+//     pc += d.InstructionDecode(buffer, pc);
+//     printf("%p    %08x      %s\n",
+//            prev_pc, *reinterpret_cast<int32_t*>(prev_pc), buffer);
+//   }
+//
+// The Disassembler class also has a convenience method to disassemble a block
+// of code into a FILE*, meaning that the above functionality could also be
+// achieved by just calling Disassembler::Disassemble(stdout, begin, end);
+
+
+#include "jit/arm/disasm/Disasm-arm.h"
+
+#ifdef JS_DISASM_ARM
+
+#include <stdarg.h>
+#include <stdio.h>
+#include <string.h>
+
+#include "jit/arm/disasm/Constants-arm.h"
+
+namespace js {
+namespace jit {
+namespace disasm {
+
+
+// Helper function for printing to a Vector.
+static int
+MOZ_FORMAT_PRINTF(2, 3)
+SNPrintF(V8Vector<char> str, const char* format, ...)
+{
+    va_list args;
+    va_start(args, format);
+    int result = vsnprintf(str.start(), str.length(), format, args);
+    va_end(args);
+    return result;
+}
+
+
+//------------------------------------------------------------------------------
+
+// Decoder decodes and disassembles instructions into an output buffer.
+// It uses the converter to convert register names and call destinations into
+// more informative description.
+class Decoder {
+  public:
+    Decoder(const disasm::NameConverter& converter,
+            V8Vector<char> out_buffer)
+        : converter_(converter),
+          out_buffer_(out_buffer),
+          out_buffer_pos_(0) {
+        out_buffer_[out_buffer_pos_] = '\0';
+    }
+
+    ~Decoder() {}
+
+    // Writes one disassembled instruction into 'buffer' (0-terminated).
+    // Returns the length of the disassembled machine instruction in bytes.
+    int InstructionDecode(uint8_t* instruction);
+
+    static bool IsConstantPoolAt(uint8_t* instr_ptr);
+    static int ConstantPoolSizeAt(uint8_t* instr_ptr);
+
+  private:
+    // Bottleneck functions to print into the out_buffer.
+    void PrintChar(const char ch);
+    void Print(const char* str);
+
+    // Printing of common values.
+    void PrintRegister(int reg);
+    void PrintSRegister(int reg);
+    void PrintDRegister(int reg);
+    int FormatVFPRegister(Instruction* instr, const char* format);
+    void PrintMovwMovt(Instruction* instr);
+    int FormatVFPinstruction(Instruction* instr, const char* format);
+    void PrintCondition(Instruction* instr);
+    void PrintShiftRm(Instruction* instr);
+    void PrintShiftImm(Instruction* instr);
+    void PrintShiftSat(Instruction* instr);
+    void PrintPU(Instruction* instr);
+    void PrintSoftwareInterrupt(SoftwareInterruptCodes svc);
+
+    // Handle formatting of instructions and their options.
+    int FormatRegister(Instruction* instr, const char* option);
+    void FormatNeonList(int Vd, int type);
+    void FormatNeonMemory(int Rn, int align, int Rm);
+    int FormatOption(Instruction* instr, const char* option);
+    void Format(Instruction* instr, const char* format);
+    void Unknown(Instruction* instr);
+
+    // Each of these functions decodes one particular instruction type, a 3-bit
+    // field in the instruction encoding.
+    // Types 0 and 1 are combined as they are largely the same except for the way
+    // they interpret the shifter operand.
+    void DecodeType01(Instruction* instr);
+    void DecodeType2(Instruction* instr);
+    void DecodeType3(Instruction* instr);
+    void DecodeType4(Instruction* instr);
+    void DecodeType5(Instruction* instr);
+    void DecodeType6(Instruction* instr);
+    // Type 7 includes special Debugger instructions.
+    int DecodeType7(Instruction* instr);
+    // For VFP support.
+    void DecodeTypeVFP(Instruction* instr);
+    void DecodeType6CoprocessorIns(Instruction* instr);
+
+    void DecodeSpecialCondition(Instruction* instr);
+
+    void DecodeVMOVBetweenCoreAndSinglePrecisionRegisters(Instruction* instr);
+    void DecodeVCMP(Instruction* instr);
+    void DecodeVCVTBetweenDoubleAndSingle(Instruction* instr);
+    void DecodeVCVTBetweenFloatingPointAndInteger(Instruction* instr);
+
+    const disasm::NameConverter& converter_;
+    V8Vector<char> out_buffer_;
+    int out_buffer_pos_;
+
+    // Disallow copy and assign.
+    Decoder(const Decoder&) = delete;
+    void operator=(const Decoder&) = delete;
+};
+
+
+// Support for assertions in the Decoder formatting functions.
+#define STRING_STARTS_WITH(string, compare_string) \
+    (strncmp(string, compare_string, strlen(compare_string)) == 0)
+
+
+// Append the ch to the output buffer.
+void
+Decoder::PrintChar(const char ch)
+{
+    out_buffer_[out_buffer_pos_++] = ch;
+}
+
+
+// Append the str to the output buffer.
+void
+Decoder::Print(const char* str)
+{
+    char cur = *str++;
+    while (cur != '\0' && (out_buffer_pos_ < int(out_buffer_.length() - 1))) {
+        PrintChar(cur);
+        cur = *str++;
+    }
+    out_buffer_[out_buffer_pos_] = 0;
+}
+
+
+// These condition names are defined in a way to match the native disassembler
+// formatting. See for example the command "objdump -d <binary file>".
+static const char* const cond_names[kNumberOfConditions] = {
+    "eq", "ne", "cs" , "cc" , "mi" , "pl" , "vs" , "vc" ,
+    "hi", "ls", "ge", "lt", "gt", "le", "", "invalid",
+};
+
+
+// Print the condition guarding the instruction.
+void
+Decoder::PrintCondition(Instruction* instr)
+{
+    Print(cond_names[instr->ConditionValue()]);
+}
+
+
+// Print the register name according to the active name converter.
+void
+Decoder::PrintRegister(int reg)
+{
+    Print(converter_.NameOfCPURegister(reg));
+}
+
+
+// Print the VFP S register name according to the active name converter.
+void
+Decoder::PrintSRegister(int reg)
+{
+    Print(VFPRegisters::Name(reg, false));
+}
+
+
+// Print the VFP D register name according to the active name converter.
+void
+Decoder::PrintDRegister(int reg)
+{
+    Print(VFPRegisters::Name(reg, true));
+}
+
+
+// These shift names are defined in a way to match the native disassembler
+// formatting. See for example the command "objdump -d <binary file>".
+static const char* const shift_names[kNumberOfShifts] = {
+    "lsl", "lsr", "asr", "ror"
+};
+
+
+// Print the register shift operands for the instruction. Generally used for
+// data processing instructions.
+void
+Decoder::PrintShiftRm(Instruction* instr)
+{
+    ShiftOp shift = instr->ShiftField();
+    int shift_index = instr->ShiftValue();
+    int shift_amount = instr->ShiftAmountValue();
+    int rm = instr->RmValue();
+
+    PrintRegister(rm);
+
+    if ((instr->RegShiftValue() == 0) && (shift == LSL) && (shift_amount == 0)) {
+        // Special case for using rm only.
+        return;
+    }
+    if (instr->RegShiftValue() == 0) {
+        // by immediate
+        if ((shift == ROR) && (shift_amount == 0)) {
+            Print(", RRX");
+            return;
+        } else if (((shift == LSR) || (shift == ASR)) && (shift_amount == 0)) {
+            shift_amount = 32;
+        }
+        out_buffer_pos_ += SNPrintF(out_buffer_ + out_buffer_pos_,
+                                    ", %s #%d",
+                                    shift_names[shift_index],
+                                    shift_amount);
+    } else {
+        // by register
+        int rs = instr->RsValue();
+        out_buffer_pos_ += SNPrintF(out_buffer_ + out_buffer_pos_,
+                                    ", %s ", shift_names[shift_index]);
+        PrintRegister(rs);
+    }
+}
+
+
+static inline uint32_t
+RotateRight32(uint32_t value, uint32_t shift)
+{
+    if (shift == 0) return value;
+    return (value >> shift) | (value << (32 - shift));
+}
+
+
+// Print the immediate operand for the instruction. Generally used for data
+// processing instructions.
+void
+Decoder::PrintShiftImm(Instruction* instr)
+{
+    int rotate = instr->RotateValue() * 2;
+    int immed8 = instr->Immed8Value();
+    int imm = RotateRight32(immed8, rotate);
+    out_buffer_pos_ += SNPrintF(out_buffer_ + out_buffer_pos_, "#%d", imm);
+}
+
+
+// Print the optional shift and immediate used by saturating instructions.
+void
+Decoder::PrintShiftSat(Instruction* instr)
+{
+    int shift = instr->Bits(11, 7);
+    if (shift > 0) {
+        out_buffer_pos_ += SNPrintF(out_buffer_ + out_buffer_pos_,
+                                    ", %s #%d",
+                                    shift_names[instr->Bit(6) * 2],
+                                    instr->Bits(11, 7));
+    }
+}
+
+
+// Print PU formatting to reduce complexity of FormatOption.
+void
+Decoder::PrintPU(Instruction* instr)
+{
+    switch (instr->PUField()) {
+      case da_x: {
+        Print("da");
+        break;
+      }
+      case ia_x: {
+        Print("ia");
+        break;
+      }
+      case db_x: {
+        Print("db");
+        break;
+      }
+      case ib_x: {
+        Print("ib");
+        break;
+      }
+      default: {
+        MOZ_CRASH();
+        break;
+      }
+    }
+}
+
+
+// Print SoftwareInterrupt codes. Factoring this out reduces the complexity of
+// the FormatOption method.
+void
+Decoder::PrintSoftwareInterrupt(SoftwareInterruptCodes svc)
+{
+    switch (svc) {
+      case kCallRtRedirected:
+        Print("call rt redirected");
+        return;
+      case kBreakpoint:
+        Print("breakpoint");
+        return;
+      default:
+        if (svc >= kStopCode) {
+            out_buffer_pos_ += SNPrintF(out_buffer_ + out_buffer_pos_,
+                                        "%d - 0x%x",
+                                        svc & kStopCodeMask,
+                                        svc & kStopCodeMask);
+        } else {
+            out_buffer_pos_ += SNPrintF(out_buffer_ + out_buffer_pos_,
+                                        "%d",
+                                        svc);
+        }
+        return;
+    }
+}
+
+
+// Handle all register based formatting in this function to reduce the
+// complexity of FormatOption.
+int
+Decoder::FormatRegister(Instruction* instr, const char* format)
+{
+    MOZ_ASSERT(format[0] == 'r');
+    if (format[1] == 'n') {  // 'rn: Rn register
+        int reg = instr->RnValue();
+        PrintRegister(reg);
+        return 2;
+    } else if (format[1] == 'd') {  // 'rd: Rd register
+        int reg = instr->RdValue();
+        PrintRegister(reg);
+        return 2;
+    } else if (format[1] == 's') {  // 'rs: Rs register
+        int reg = instr->RsValue();
+        PrintRegister(reg);
+        return 2;
+    } else if (format[1] == 'm') {  // 'rm: Rm register
+        int reg = instr->RmValue();
+        PrintRegister(reg);
+        return 2;
+    } else if (format[1] == 't') {  // 'rt: Rt register
+        int reg = instr->RtValue();
+        PrintRegister(reg);
+        return 2;
+    } else if (format[1] == 'l') {
+        // 'rlist: register list for load and store multiple instructions
+        MOZ_ASSERT(STRING_STARTS_WITH(format, "rlist"));
+        int rlist = instr->RlistValue();
+        int reg = 0;
+        Print("{");
+        // Print register list in ascending order, by scanning the bit mask.
+        while (rlist != 0) {
+            if ((rlist & 1) != 0) {
+                PrintRegister(reg);
+                if ((rlist >> 1) != 0) {
+                    Print(", ");
+                }
+            }
+            reg++;
+            rlist >>= 1;
+        }
+        Print("}");
+        return 5;
+    }
+    MOZ_CRASH();
+    return -1;
+}
+
+
+// Handle all VFP register based formatting in this function to reduce the
+// complexity of FormatOption.
+int
+Decoder::FormatVFPRegister(Instruction* instr, const char* format)
+{
+    MOZ_ASSERT((format[0] == 'S') || (format[0] == 'D'));
+
+    VFPRegPrecision precision =
+        format[0] == 'D' ? kDoublePrecision : kSinglePrecision;
+
+    int retval = 2;
+    int reg = -1;
+    if (format[1] == 'n') {
+        reg = instr->VFPNRegValue(precision);
+    } else if (format[1] == 'm') {
+        reg = instr->VFPMRegValue(precision);
+    } else if (format[1] == 'd') {
+        if ((instr->TypeValue() == 7) &&
+            (instr->Bit(24) == 0x0) &&
+            (instr->Bits(11, 9) == 0x5) &&
+            (instr->Bit(4) == 0x1)) {
+            // vmov.32 has Vd in a different place.
+            reg = instr->Bits(19, 16) | (instr->Bit(7) << 4);
+        } else {
+            reg = instr->VFPDRegValue(precision);
+        }
+
+        if (format[2] == '+') {
+            int immed8 = instr->Immed8Value();
+            if (format[0] == 'S') reg += immed8 - 1;
+            if (format[0] == 'D') reg += (immed8 / 2 - 1);
+        }
+        if (format[2] == '+') retval = 3;
+    } else {
+        MOZ_CRASH();
+    }
+
+    if (precision == kSinglePrecision) {
+        PrintSRegister(reg);
+    } else {
+        PrintDRegister(reg);
+    }
+
+    return retval;
+}
+
+
+int
+Decoder::FormatVFPinstruction(Instruction* instr, const char* format)
+{
+    Print(format);
+    return 0;
+}
+
+
+void
+Decoder::FormatNeonList(int Vd, int type)
+{
+    if (type == nlt_1) {
+        out_buffer_pos_ += SNPrintF(out_buffer_ + out_buffer_pos_,
+                                    "{d%d}", Vd);
+    } else if (type == nlt_2) {
+        out_buffer_pos_ += SNPrintF(out_buffer_ + out_buffer_pos_,
+                                    "{d%d, d%d}", Vd, Vd + 1);
+    } else if (type == nlt_3) {
+        out_buffer_pos_ += SNPrintF(out_buffer_ + out_buffer_pos_,
+                                    "{d%d, d%d, d%d}", Vd, Vd + 1, Vd + 2);
+    } else if (type == nlt_4) {
+        out_buffer_pos_ += SNPrintF(out_buffer_ + out_buffer_pos_,
+                                    "{d%d, d%d, d%d, d%d}", Vd, Vd + 1, Vd + 2, Vd + 3);
+    }
+}
+
+
+void
+Decoder::FormatNeonMemory(int Rn, int align, int Rm)
+{
+    out_buffer_pos_ += SNPrintF(out_buffer_ + out_buffer_pos_,
+                                "[r%d", Rn);
+    if (align != 0) {
+        out_buffer_pos_ += SNPrintF(out_buffer_ + out_buffer_pos_,
+                                    ":%d", (1 << align) << 6);
+    }
+    if (Rm == 15) {
+        Print("]");
+    } else if (Rm == 13) {
+        Print("]!");
+    } else {
+        out_buffer_pos_ += SNPrintF(out_buffer_ + out_buffer_pos_,
+                                    "], r%d", Rm);
+    }
+}
+
+
+// Print the movw or movt instruction.
+void
+Decoder::PrintMovwMovt(Instruction* instr)
+{
+    int imm = instr->ImmedMovwMovtValue();
+    int rd = instr->RdValue();
+    PrintRegister(rd);
+    out_buffer_pos_ += SNPrintF(out_buffer_ + out_buffer_pos_, ", #%d", imm);
+}
+
+
+// FormatOption takes a formatting string and interprets it based on
+// the current instructions. The format string points to the first
+// character of the option string (the option escape has already been
+// consumed by the caller.)  FormatOption returns the number of
+// characters that were consumed from the formatting string.
+int Decoder::FormatOption(Instruction* instr, const char* format)
+{
+    switch (format[0]) {
+      case 'a': {  // 'a: accumulate multiplies
+        if (instr->Bit(21) == 0) {
+            Print("ul");
+        } else {
+            Print("la");
+        }
+        return 1;
+      }
+      case 'b': {  // 'b: byte loads or stores
+        if (instr->HasB()) {
+            Print("b");
+        }
+        return 1;
+      }
+      case 'c': {  // 'cond: conditional execution
+        MOZ_ASSERT(STRING_STARTS_WITH(format, "cond"));
+        PrintCondition(instr);
+        return 4;
+      }
+      case 'd': {  // 'd: vmov double immediate.
+        double d = instr->DoubleImmedVmov();
+        out_buffer_pos_ += SNPrintF(out_buffer_ + out_buffer_pos_, "#%g", d);
+        return 1;
+      }
+      case 'f': {  // 'f: bitfield instructions - v7 and above.
+        uint32_t lsbit = instr->Bits(11, 7);
+        uint32_t width = instr->Bits(20, 16) + 1;
+        if (instr->Bit(21) == 0) {
+            // BFC/BFI:
+            // Bits 20-16 represent most-significant bit. Covert to width.
+            width -= lsbit;
+            MOZ_ASSERT(width > 0);
+        }
+        MOZ_ASSERT((width + lsbit) <= 32);
+        out_buffer_pos_ += SNPrintF(out_buffer_ + out_buffer_pos_,
+                                    "#%d, #%d", lsbit, width);
+        return 1;
+      }
+      case 'h': {  // 'h: halfword operation for extra loads and stores
+        if (instr->HasH()) {
+            Print("h");
+        } else {
+            Print("b");
+        }
+        return 1;
+      }
+      case 'i': {  // 'i: immediate value from adjacent bits.
+        // Expects tokens in the form imm%02d@%02d, i.e. imm05@07, imm10@16
+        int width = (format[3] - '0') * 10 + (format[4] - '0');
+        int lsb   = (format[6] - '0') * 10 + (format[7] - '0');
+
+        MOZ_ASSERT((width >= 1) && (width <= 32));
+        MOZ_ASSERT((lsb >= 0) && (lsb <= 31));
+        MOZ_ASSERT((width + lsb) <= 32);
+
+        out_buffer_pos_ += SNPrintF(out_buffer_ + out_buffer_pos_,
+                                    "%d",
+                                    instr->Bits(width + lsb - 1, lsb));
+        return 8;
+      }
+      case 'l': {  // 'l: branch and link
+        if (instr->HasLink()) {
+            Print("l");
+        }
+        return 1;
+      }
+      case 'm': {
+        if (format[1] == 'w') {
+            // 'mw: movt/movw instructions.
+            PrintMovwMovt(instr);
+            return 2;
+        }
+        if (format[1] == 'e') {  // 'memop: load/store instructions.
+            MOZ_ASSERT(STRING_STARTS_WITH(format, "memop"));
+            if (instr->HasL()) {
+                Print("ldr");
+            } else {
+                if ((instr->Bits(27, 25) == 0) && (instr->Bit(20) == 0) &&
+                    (instr->Bits(7, 6) == 3) && (instr->Bit(4) == 1)) {
+                    if (instr->Bit(5) == 1) {
+                        Print("strd");
+                    } else {
+                        Print("ldrd");
+                    }
+                    return 5;
+                }
+                Print("str");
+            }
+            return 5;
+        }
+        // 'msg: for simulator break instructions
+        MOZ_ASSERT(STRING_STARTS_WITH(format, "msg"));
+        uint8_t* str =
+            reinterpret_cast<uint8_t*>(instr->InstructionBits() & 0x0fffffff);
+        out_buffer_pos_ += SNPrintF(out_buffer_ + out_buffer_pos_,
+                                    "%s", converter_.NameInCode(str));
+        return 3;
+      }
+      case 'o': {
+        if ((format[3] == '1') && (format[4] == '2')) {
+            // 'off12: 12-bit offset for load and store instructions
+            MOZ_ASSERT(STRING_STARTS_WITH(format, "off12"));
+            out_buffer_pos_ += SNPrintF(out_buffer_ + out_buffer_pos_,
+                                        "%d", instr->Offset12Value());
+            return 5;
+        } else if (format[3] == '0') {
+            // 'off0to3and8to19 16-bit immediate encoded in bits 19-8 and 3-0.
+            MOZ_ASSERT(STRING_STARTS_WITH(format, "off0to3and8to19"));
+            out_buffer_pos_ += SNPrintF(out_buffer_ + out_buffer_pos_,
+                                        "%d",
+                                        (instr->Bits(19, 8) << 4) +
+                                        instr->Bits(3, 0));
+            return 15;
+        }
+        // 'off8: 8-bit offset for extra load and store instructions
+        MOZ_ASSERT(STRING_STARTS_WITH(format, "off8"));
+        int offs8 = (instr->ImmedHValue() << 4) | instr->ImmedLValue();
+        out_buffer_pos_ += SNPrintF(out_buffer_ + out_buffer_pos_, "%d", offs8);
+        return 4;
+      }
+      case 'p': {  // 'pu: P and U bits for load and store instructions
+        MOZ_ASSERT(STRING_STARTS_WITH(format, "pu"));
+        PrintPU(instr);
+        return 2;
+      }
+      case 'r': {
+        return FormatRegister(instr, format);
+      }
+      case 's': {
+        if (format[1] == 'h') {  // 'shift_op or 'shift_rm or 'shift_sat.
+            if (format[6] == 'o') {  // 'shift_op
+                MOZ_ASSERT(STRING_STARTS_WITH(format, "shift_op"));
+                if (instr->TypeValue() == 0) {
+                    PrintShiftRm(instr);
+                } else {
+                    MOZ_ASSERT(instr->TypeValue() == 1);
+                    PrintShiftImm(instr);
+                }
+                return 8;
+            } else if (format[6] == 's') {  // 'shift_sat.
+                MOZ_ASSERT(STRING_STARTS_WITH(format, "shift_sat"));
+                PrintShiftSat(instr);
+                return 9;
+            } else {  // 'shift_rm
+                MOZ_ASSERT(STRING_STARTS_WITH(format, "shift_rm"));
+                PrintShiftRm(instr);
+                return 8;
+            }
+        } else if (format[1] == 'v') {  // 'svc
+            MOZ_ASSERT(STRING_STARTS_WITH(format, "svc"));
+            PrintSoftwareInterrupt(instr->SvcValue());
+            return 3;
+        } else if (format[1] == 'i') {  // 'sign: signed extra loads and stores
+            MOZ_ASSERT(STRING_STARTS_WITH(format, "sign"));
+            if (instr->HasSign()) {
+                Print("s");
+            }
+            return 4;
+        }
+        // 's: S field of data processing instructions
+        if (instr->HasS()) {
+            Print("s");
+        }
+        return 1;
+      }
+      case 't': {  // 'target: target of branch instructions
+        MOZ_ASSERT(STRING_STARTS_WITH(format, "target"));
+        int off = (instr->SImmed24Value() << 2) + 8;
+        out_buffer_pos_ += SNPrintF(out_buffer_ + out_buffer_pos_,
+                                    "%+d -> %s",
+                                    off,
+                                    converter_.NameOfAddress(
+                                        reinterpret_cast<uint8_t*>(instr) + off));
+        return 6;
+      }
+      case 'u': {  // 'u: signed or unsigned multiplies
+        // The manual gets the meaning of bit 22 backwards in the multiply
+        // instruction overview on page A3.16.2.  The instructions that
+        // exist in u and s variants are the following:
+        // smull A4.1.87
+        // umull A4.1.129
+        // umlal A4.1.128
+        // smlal A4.1.76
+        // For these 0 means u and 1 means s.  As can be seen on their individual
+        // pages.  The other 18 mul instructions have the bit set or unset in
+        // arbitrary ways that are unrelated to the signedness of the instruction.
+        // None of these 18 instructions exist in both a 'u' and an 's' variant.
+
+        if (instr->Bit(22) == 0) {
+            Print("u");
+        } else {
+            Print("s");
+        }
+        return 1;
+      }
+      case 'v': {
+        return FormatVFPinstruction(instr, format);
+      }
+      case 'S':
+      case 'D': {
+        return FormatVFPRegister(instr, format);
+      }
+      case 'w': {  // 'w: W field of load and store instructions
+        if (instr->HasW()) {
+            Print("!");
+        }
+        return 1;
+      }
+      default: {
+        MOZ_CRASH();
+        break;
+      }
+    }
+    MOZ_CRASH();
+    return -1;
+}
+
+
+// Format takes a formatting string for a whole instruction and prints it into
+// the output buffer. All escaped options are handed to FormatOption to be
+// parsed further.
+void
+Decoder::Format(Instruction* instr, const char* format)
+{
+    char cur = *format++;
+    while ((cur != 0) && (out_buffer_pos_ < (out_buffer_.length() - 1))) {
+        if (cur == '\'') {  // Single quote is used as the formatting escape.
+            format += FormatOption(instr, format);
+        } else {
+            out_buffer_[out_buffer_pos_++] = cur;
+        }
+        cur = *format++;
+    }
+    out_buffer_[out_buffer_pos_]  = '\0';
+}
+
+
+// The disassembler may end up decoding data inlined in the code. We do not want
+// it to crash if the data does not ressemble any known instruction.
+#define VERIFY(condition) \
+    if(!(condition)) {    \
+        Unknown(instr);   \
+        return;           \
+    }
+
+
+// For currently unimplemented decodings the disassembler calls Unknown(instr)
+// which will just print "unknown" of the instruction bits.
+void
+Decoder::Unknown(Instruction* instr)
+{
+    Format(instr, "unknown");
+}
+
+
+void
+Decoder::DecodeType01(Instruction* instr)
+{
+    int type = instr->TypeValue();
+    if ((type == 0) && instr->IsSpecialType0()) {
+        // multiply instruction or extra loads and stores
+        if (instr->Bits(7, 4) == 9) {
+            if (instr->Bit(24) == 0) {
+                // multiply instructions
+                if (instr->Bit(23) == 0) {
+                    if (instr->Bit(21) == 0) {
+                        // The MUL instruction description (A 4.1.33) refers to Rd as being
+                        // the destination for the operation, but it confusingly uses the
+                        // Rn field to encode it.
+                        Format(instr, "mul'cond's 'rn, 'rm, 'rs");
+                    } else {
+                        if (instr->Bit(22) == 0) {
+                            // The MLA instruction description (A 4.1.28) refers to the order
+                            // of registers as "Rd, Rm, Rs, Rn". But confusingly it uses the
+                            // Rn field to encode the Rd register and the Rd field to encode
+                            // the Rn register.
+                            Format(instr, "mla'cond's 'rn, 'rm, 'rs, 'rd");
+                        } else {
+                            // The MLS instruction description (A 4.1.29) refers to the order
+                            // of registers as "Rd, Rm, Rs, Rn". But confusingly it uses the
+                            // Rn field to encode the Rd register and the Rd field to encode
+                            // the Rn register.
+                            Format(instr, "mls'cond's 'rn, 'rm, 'rs, 'rd");
+                        }
+                    }
+                } else {
+                    // The signed/long multiply instructions use the terms RdHi and RdLo
+                    // when referring to the target registers. They are mapped to the Rn
+                    // and Rd fields as follows:
+                    // RdLo == Rd field
+                    // RdHi == Rn field
+                    // The order of registers is: <RdLo>, <RdHi>, <Rm>, <Rs>
+                    Format(instr, "'um'al'cond's 'rd, 'rn, 'rm, 'rs");
+                }
+            } else {
+                if (instr->Bits(ExclusiveOpHi, ExclusiveOpLo) == ExclusiveOpcode) {
+                    if (instr->Bit(ExclusiveLoad) == 1) {
+                        switch (instr->Bits(ExclusiveSizeHi, ExclusiveSizeLo)) {
+                          case ExclusiveWord:
+                            Format(instr, "ldrex'cond 'rt, ['rn]");
+                            break;
+                          case ExclusiveDouble:
+                            Format(instr, "ldrexd'cond 'rt, ['rn]");
+                            break;
+                          case ExclusiveByte:
+                            Format(instr, "ldrexb'cond 'rt, ['rn]");
+                            break;
+                          case ExclusiveHalf:
+                            Format(instr, "ldrexh'cond 'rt, ['rn]");
+                            break;
+                        }
+                    } else {
+                        // The documentation names the low four bits of the
+                        // store-exclusive instructions "Rt" but canonically
+                        // for disassembly they are really "Rm".
+                        switch (instr->Bits(ExclusiveSizeHi, ExclusiveSizeLo)) {
+                          case ExclusiveWord:
+                            Format(instr, "strex'cond 'rd, 'rm, ['rn]");
+                            break;
+                          case ExclusiveDouble:
+                            Format(instr, "strexd'cond 'rd, 'rm, ['rn]");
+                            break;
+                          case ExclusiveByte:
+                            Format(instr, "strexb'cond 'rd, 'rm, ['rn]");
+                            break;
+                          case ExclusiveHalf:
+                            Format(instr, "strexh'cond 'rd, 'rm, ['rn]");
+                            break;
+                        }
+                    }
+                } else {
+                    Unknown(instr);
+                }
+            }
+        } else if ((instr->Bit(20) == 0) && ((instr->Bits(7, 4) & 0xd) == 0xd)) {
+            // ldrd, strd
+            switch (instr->PUField()) {
+              case da_x: {
+                if (instr->Bit(22) == 0) {
+                    Format(instr, "'memop'cond's 'rd, ['rn], -'rm");
+                } else {
+                    Format(instr, "'memop'cond's 'rd, ['rn], #-'off8");
+                }
+                break;
+              }
+              case ia_x: {
+                if (instr->Bit(22) == 0) {
+                    Format(instr, "'memop'cond's 'rd, ['rn], +'rm");
+                } else {
+                    Format(instr, "'memop'cond's 'rd, ['rn], #+'off8");
+                }
+                break;
+              }
+              case db_x: {
+                if (instr->Bit(22) == 0) {
+                    Format(instr, "'memop'cond's 'rd, ['rn, -'rm]'w");
+                } else {
+                    Format(instr, "'memop'cond's 'rd, ['rn, #-'off8]'w");
+                }
+                break;
+              }
+              case ib_x: {
+                if (instr->Bit(22) == 0) {
+                    Format(instr, "'memop'cond's 'rd, ['rn, +'rm]'w");
+                } else {
+                    Format(instr, "'memop'cond's 'rd, ['rn, #+'off8]'w");
+                }
+                break;
+              }
+              default: {
+                // The PU field is a 2-bit field.
+                MOZ_CRASH();
+                break;
+              }
+            }
+        } else {
+            // extra load/store instructions
+            switch (instr->PUField()) {
+              case da_x: {
+                if (instr->Bit(22) == 0) {
+                    Format(instr, "'memop'cond'sign'h 'rd, ['rn], -'rm");
+                } else {
+                    Format(instr, "'memop'cond'sign'h 'rd, ['rn], #-'off8");
+                }
+                break;
+              }
+              case ia_x: {
+                if (instr->Bit(22) == 0) {
+                    Format(instr, "'memop'cond'sign'h 'rd, ['rn], +'rm");
+                } else {
+                    Format(instr, "'memop'cond'sign'h 'rd, ['rn], #+'off8");
+                }
+                break;
+              }
+              case db_x: {
+                if (instr->Bit(22) == 0) {
+                    Format(instr, "'memop'cond'sign'h 'rd, ['rn, -'rm]'w");
+                } else {
+                    Format(instr, "'memop'cond'sign'h 'rd, ['rn, #-'off8]'w");
+                }
+                break;
+              }
+              case ib_x: {
+                if (instr->Bit(22) == 0) {
+                    Format(instr, "'memop'cond'sign'h 'rd, ['rn, +'rm]'w");
+                } else {
+                    Format(instr, "'memop'cond'sign'h 'rd, ['rn, #+'off8]'w");
+                }
+                break;
+              }
+              default: {
+                // The PU field is a 2-bit field.
+                MOZ_CRASH();
+                break;
+              }
+            }
+            return;
+        }
+    } else if ((type == 0) && instr->IsMiscType0()) {
+        if (instr->Bits(22, 21) == 1) {
+            switch (instr->BitField(7, 4)) {
+              case BX:
+                Format(instr, "bx'cond 'rm");
+                break;
+              case BLX:
+                Format(instr, "blx'cond 'rm");
+                break;
+              case BKPT:
+                Format(instr, "bkpt 'off0to3and8to19");
+                break;
+              default:
+                Unknown(instr);  // not used by V8
+                break;
+            }
+        } else if (instr->Bits(22, 21) == 3) {
+            switch (instr->BitField(7, 4)) {
+              case CLZ:
+                Format(instr, "clz'cond 'rd, 'rm");
+                break;
+              default:
+                Unknown(instr);  // not used by V8
+                break;
+            }
+        } else {
+            Unknown(instr);  // not used by V8
+        }
+    } else if ((type == 1) && instr->IsNopType1()) {
+        Format(instr, "nop'cond");
+    } else {
+        switch (instr->OpcodeField()) {
+          case AND: {
+            Format(instr, "and'cond's 'rd, 'rn, 'shift_op");
+             break;
+          }
+          case EOR: {
+            Format(instr, "eor'cond's 'rd, 'rn, 'shift_op");
+             break;
+          }
+          case SUB: {
+            Format(instr, "sub'cond's 'rd, 'rn, 'shift_op");
+            break;
+          }
+          case RSB: {
+            Format(instr, "rsb'cond's 'rd, 'rn, 'shift_op");
+            break;
+          }
+          case ADD: {
+            Format(instr, "add'cond's 'rd, 'rn, 'shift_op");
+            break;
+          }
+          case ADC: {
+            Format(instr, "adc'cond's 'rd, 'rn, 'shift_op");
+            break;
+          }
+          case SBC: {
+            Format(instr, "sbc'cond's 'rd, 'rn, 'shift_op");
+            break;
+          }
+          case RSC: {
+            Format(instr, "rsc'cond's 'rd, 'rn, 'shift_op");
+            break;
+          }
+          case TST: {
+            if (instr->HasS()) {
+                Format(instr, "tst'cond 'rn, 'shift_op");
+            } else {
+                Format(instr, "movw'cond 'mw");
+            }
+            break;
+          }
+          case TEQ: {
+            if (instr->HasS()) {
+                Format(instr, "teq'cond 'rn, 'shift_op");
+            } else {
+                // Other instructions matching this pattern are handled in the
+                // miscellaneous instructions part above.
+                MOZ_CRASH();
+            }
+            break;
+          }
+          case CMP: {
+            if (instr->HasS()) {
+                Format(instr, "cmp'cond 'rn, 'shift_op");
+            } else {
+                Format(instr, "movt'cond 'mw");
+            }
+            break;
+          }
+          case CMN: {
+            if (instr->HasS()) {
+                Format(instr, "cmn'cond 'rn, 'shift_op");
+            } else {
+                // Other instructions matching this pattern are handled in the
+                // miscellaneous instructions part above.
+                MOZ_CRASH();
+            }
+            break;
+          }
+          case ORR: {
+            Format(instr, "orr'cond's 'rd, 'rn, 'shift_op");
+            break;
+          }
+          case MOV: {
+            Format(instr, "mov'cond's 'rd, 'shift_op");
+            break;
+          }
+          case BIC: {
+            Format(instr, "bic'cond's 'rd, 'rn, 'shift_op");
+            break;
+          }
+          case MVN: {
+            Format(instr, "mvn'cond's 'rd, 'shift_op");
+            break;
+          }
+          default: {
+            // The Opcode field is a 4-bit field.
+            MOZ_CRASH();
+            break;
+          }
+        }
+    }
+}
+
+
+void
+Decoder::DecodeType2(Instruction* instr)
+{
+    switch (instr->PUField()) {
+      case da_x: {
+        if (instr->HasW()) {
+            Unknown(instr);  // not used in V8
+            return;
+        }
+        Format(instr, "'memop'cond'b 'rd, ['rn], #-'off12");
+        break;
+      }
+      case ia_x: {
+          if (instr->HasW()) {
+            Unknown(instr);  // not used in V8
+            return;
+        }
+        Format(instr, "'memop'cond'b 'rd, ['rn], #+'off12");
+        break;
+      }
+      case db_x: {
+        Format(instr, "'memop'cond'b 'rd, ['rn, #-'off12]'w");
+        break;
+      }
+      case ib_x: {
+        Format(instr, "'memop'cond'b 'rd, ['rn, #+'off12]'w");
+        break;
+      }
+      default: {
+        // The PU field is a 2-bit field.
+        MOZ_CRASH();
+        break;
+      }
+    }
+}
+
+
+void
+Decoder::DecodeType3(Instruction* instr)
+{
+    switch (instr->PUField()) {
+      case da_x: {
+        VERIFY(!instr->HasW());
+        Format(instr, "'memop'cond'b 'rd, ['rn], -'shift_rm");
+        break;
+      }
+      case ia_x: {
+        if (instr->Bit(4) == 0) {
+            Format(instr, "'memop'cond'b 'rd, ['rn], +'shift_rm");
+        } else {
+            if (instr->Bit(5) == 0) {
+                switch (instr->Bits(22, 21)) {
+                  case 0:
+                    if (instr->Bit(20) == 0) {
+                        if (instr->Bit(6) == 0) {
+                            Format(instr, "pkhbt'cond 'rd, 'rn, 'rm, lsl #'imm05@07");
+                        } else {
+                            if (instr->Bits(11, 7) == 0) {
+                                Format(instr, "pkhtb'cond 'rd, 'rn, 'rm, asr #32");
+                            } else {
+                                Format(instr, "pkhtb'cond 'rd, 'rn, 'rm, asr #'imm05@07");
+                            }
+                        }
+                    } else {
+                        MOZ_CRASH();
+                    }
+                    break;
+                  case 1:
+                    MOZ_CRASH();
+                    break;
+                  case 2:
+                    MOZ_CRASH();
+                    break;
+                  case 3:
+                    Format(instr, "usat 'rd, #'imm05@16, 'rm'shift_sat");
+                    break;
+                }
+            } else {
+                switch (instr->Bits(22, 21)) {
+                  case 0:
+                    MOZ_CRASH();
+                    break;
+                  case 1:
+                    if (instr->Bits(9, 6) == 1) {
+                        if (instr->Bit(20) == 0) {
+                            if (instr->Bits(19, 16) == 0xF) {
+                                switch (instr->Bits(11, 10)) {
+                                  case 0:
+                                    Format(instr, "sxtb'cond 'rd, 'rm");
+                                    break;
+                                  case 1:
+                                    Format(instr, "sxtb'cond 'rd, 'rm, ror #8");
+                                    break;
+                                  case 2:
+                                    Format(instr, "sxtb'cond 'rd, 'rm, ror #16");
+                                    break;
+                                  case 3:
+                                    Format(instr, "sxtb'cond 'rd, 'rm, ror #24");
+                                    break;
+                                }
+                            } else {
+                                switch (instr->Bits(11, 10)) {
+                                  case 0:
+                                    Format(instr, "sxtab'cond 'rd, 'rn, 'rm");
+                                    break;
+                                  case 1:
+                                    Format(instr, "sxtab'cond 'rd, 'rn, 'rm, ror #8");
+                                    break;
+                                  case 2:
+                                    Format(instr, "sxtab'cond 'rd, 'rn, 'rm, ror #16");
+                                    break;
+                                  case 3:
+                                    Format(instr, "sxtab'cond 'rd, 'rn, 'rm, ror #24");
+                                    break;
+                                }
+                            }
+                        } else {
+                            if (instr->Bits(19, 16) == 0xF) {
+                                switch (instr->Bits(11, 10)) {
+                                  case 0:
+                                    Format(instr, "sxth'cond 'rd, 'rm");
+                                    break;
+                                  case 1:
+                                    Format(instr, "sxth'cond 'rd, 'rm, ror #8");
+                                    break;
+                                  case 2:
+                                    Format(instr, "sxth'cond 'rd, 'rm, ror #16");
+                                    break;
+                                  case 3:
+                                    Format(instr, "sxth'cond 'rd, 'rm, ror #24");
+                                    break;
+                                }
+                            } else {
+                                switch (instr->Bits(11, 10)) {
+                                  case 0:
+                                    Format(instr, "sxtah'cond 'rd, 'rn, 'rm");
+                                    break;
+                                  case 1:
+                                    Format(instr, "sxtah'cond 'rd, 'rn, 'rm, ror #8");
+                                    break;
+                                  case 2:
+                                    Format(instr, "sxtah'cond 'rd, 'rn, 'rm, ror #16");
+                                    break;
+                                  case 3:
+                                    Format(instr, "sxtah'cond 'rd, 'rn, 'rm, ror #24");
+                                    break;
+                                }
+                            }
+                        }
+                    } else {
+                        MOZ_CRASH();
+                    }
+                    break;
+                  case 2:
+                    if ((instr->Bit(20) == 0) && (instr->Bits(9, 6) == 1)) {
+                        if (instr->Bits(19, 16) == 0xF) {
+                            switch (instr->Bits(11, 10)) {
+                              case 0:
+                                Format(instr, "uxtb16'cond 'rd, 'rm");
+                                break;
+                              case 1:
+                                Format(instr, "uxtb16'cond 'rd, 'rm, ror #8");
+                                break;
+                              case 2:
+                                Format(instr, "uxtb16'cond 'rd, 'rm, ror #16");
+                                break;
+                              case 3:
+                                Format(instr, "uxtb16'cond 'rd, 'rm, ror #24");
+                                break;
+                            }
+                        } else {
+                            MOZ_CRASH();
+                        }
+                    } else {
+                        MOZ_CRASH();
+                    }
+                    break;
+                  case 3:
+                    if ((instr->Bits(9, 6) == 1)) {
+                        if ((instr->Bit(20) == 0)) {
+                            if (instr->Bits(19, 16) == 0xF) {
+                                switch (instr->Bits(11, 10)) {
+                                  case 0:
+                                    Format(instr, "uxtb'cond 'rd, 'rm");
+                                    break;
+                                  case 1:
+                                    Format(instr, "uxtb'cond 'rd, 'rm, ror #8");
+                                    break;
+                                  case 2:
+                                    Format(instr, "uxtb'cond 'rd, 'rm, ror #16");
+                                    break;
+                                  case 3:
+                                    Format(instr, "uxtb'cond 'rd, 'rm, ror #24");
+                                    break;
+                                }
+                            } else {
+                                switch (instr->Bits(11, 10)) {
+                                  case 0:
+                                    Format(instr, "uxtab'cond 'rd, 'rn, 'rm");
+                                    break;
+                                  case 1:
+                                    Format(instr, "uxtab'cond 'rd, 'rn, 'rm, ror #8");
+                                    break;
+                                  case 2:
+                                    Format(instr, "uxtab'cond 'rd, 'rn, 'rm, ror #16");
+                                    break;
+                                  case 3:
+                                    Format(instr, "uxtab'cond 'rd, 'rn, 'rm, ror #24");
+                                    break;
+                                }
+                            }
+                        } else {
+                            if (instr->Bits(19, 16) == 0xF) {
+                                switch (instr->Bits(11, 10)) {
+                                  case 0:
+                                    Format(instr, "uxth'cond 'rd, 'rm");
+                                    break;
+                                  case 1:
+                                    Format(instr, "uxth'cond 'rd, 'rm, ror #8");
+                                    break;
+                                  case 2:
+                                    Format(instr, "uxth'cond 'rd, 'rm, ror #16");
+                                    break;
+                                  case 3:
+                                    Format(instr, "uxth'cond 'rd, 'rm, ror #24");
+                                    break;
+                                }
+                            } else {
+                                switch (instr->Bits(11, 10)) {
+                                  case 0:
+                                    Format(instr, "uxtah'cond 'rd, 'rn, 'rm");
+                                    break;
+                                  case 1:
+                                    Format(instr, "uxtah'cond 'rd, 'rn, 'rm, ror #8");
+                                    break;
+                                  case 2:
+                                    Format(instr, "uxtah'cond 'rd, 'rn, 'rm, ror #16");
+                                    break;
+                                  case 3:
+                                    Format(instr, "uxtah'cond 'rd, 'rn, 'rm, ror #24");
+                                    break;
+                                }
+                            }
+                        }
+                    } else {
+                        MOZ_CRASH();
+                    }
+                    break;
+                }
+            }
+        }
+        break;
+      }
+      case db_x: {
+        if (instr->Bits(22, 20) == 0x5) {
+            if (instr->Bits(7, 4) == 0x1) {
+                if (instr->Bits(15, 12) == 0xF) {
+                    Format(instr, "smmul'cond 'rn, 'rm, 'rs");
+                } else {
+                    // SMMLA (in V8 notation matching ARM ISA format)
+                    Format(instr, "smmla'cond 'rn, 'rm, 'rs, 'rd");
+                }
+                break;
+            }
+        }
+        bool FLAG_enable_sudiv = true; // Flag doesn't exist in our engine.
+        if (FLAG_enable_sudiv) {
+            if (instr->Bits(5, 4) == 0x1) {
+                if ((instr->Bit(22) == 0x0) && (instr->Bit(20) == 0x1)) {
+                    if (instr->Bit(21) == 0x1) {
+                        // UDIV (in V8 notation matching ARM ISA format) rn = rm/rs
+                        Format(instr, "udiv'cond'b 'rn, 'rm, 'rs");
+                    } else {
+                        // SDIV (in V8 notation matching ARM ISA format) rn = rm/rs
+                        Format(instr, "sdiv'cond'b 'rn, 'rm, 'rs");
+                    }
+                    break;
+                }
+            }
+        }
+        Format(instr, "'memop'cond'b 'rd, ['rn, -'shift_rm]'w");
+        break;
+      }
+      case ib_x: {
+        if (instr->HasW() && (instr->Bits(6, 4) == 0x5)) {
+            uint32_t widthminus1 = static_cast<uint32_t>(instr->Bits(20, 16));
+            uint32_t lsbit = static_cast<uint32_t>(instr->Bits(11, 7));
+            uint32_t msbit = widthminus1 + lsbit;
+            if (msbit <= 31) {
+                if (instr->Bit(22)) {
+                    Format(instr, "ubfx'cond 'rd, 'rm, 'f");
+                } else {
+                    Format(instr, "sbfx'cond 'rd, 'rm, 'f");
+                }
+            } else {
+                MOZ_CRASH();
+            }
+        } else if (!instr->HasW() && (instr->Bits(6, 4) == 0x1)) {
+            uint32_t lsbit = static_cast<uint32_t>(instr->Bits(11, 7));
+            uint32_t msbit = static_cast<uint32_t>(instr->Bits(20, 16));
+            if (msbit >= lsbit) {
+                if (instr->RmValue() == 15) {
+                    Format(instr, "bfc'cond 'rd, 'f");
+                } else {
+                    Format(instr, "bfi'cond 'rd, 'rm, 'f");
+                }
+            } else {
+                MOZ_CRASH();
+            }
+        } else {
+            Format(instr, "'memop'cond'b 'rd, ['rn, +'shift_rm]'w");
+        }
+        break;
+      }
+      default: {
+        // The PU field is a 2-bit field.
+        MOZ_CRASH();
+        break;
+      }
+    }
+}
+
+
+void
+Decoder::DecodeType4(Instruction* instr)
+{
+    if (instr->Bit(22) != 0) {
+        // Privileged mode currently not supported.
+        Unknown(instr);
+    } else {
+        if (instr->HasL()) {
+            Format(instr, "ldm'cond'pu 'rn'w, 'rlist");
+        } else {
+            Format(instr, "stm'cond'pu 'rn'w, 'rlist");
+        }
+    }
+}
+
+
+void
+Decoder::DecodeType5(Instruction* instr)
+{
+    Format(instr, "b'l'cond 'target");
+}
+
+
+void
+Decoder::DecodeType6(Instruction* instr)
+{
+    DecodeType6CoprocessorIns(instr);
+}
+
+
+int
+Decoder::DecodeType7(Instruction* instr)
+{
+    if (instr->Bit(24) == 1) {
+        if (instr->SvcValue() >= kStopCode) {
+            Format(instr, "stop'cond 'svc");
+            // Also print the stop message. Its address is encoded
+            // in the following 4 bytes.
+            out_buffer_pos_ += SNPrintF(out_buffer_ + out_buffer_pos_,
+                                        "\n  %p  %08x       stop message: %s",
+                                        reinterpret_cast<void*>(instr
+                                                                + Instruction::kInstrSize),
+                                        *reinterpret_cast<uint32_t*>(instr
+                                                                     + Instruction::kInstrSize),
+                                        *reinterpret_cast<char**>(instr
+                                                                  + Instruction::kInstrSize));
+            // We have decoded 2 * Instruction::kInstrSize bytes.
+            return 2 * Instruction::kInstrSize;
+        } else {
+            Format(instr, "svc'cond 'svc");
+        }
+    } else {
+        DecodeTypeVFP(instr);
+    }
+    return Instruction::kInstrSize;
+}
+
+
+// void Decoder::DecodeTypeVFP(Instruction* instr)
+// vmov: Sn = Rt
+// vmov: Rt = Sn
+// vcvt: Dd = Sm
+// vcvt: Sd = Dm
+// vcvt.f64.s32 Dd, Dd, #<fbits>
+// Dd = vabs(Dm)
+// Sd = vabs(Sm)
+// Dd = vneg(Dm)
+// Sd = vneg(Sm)
+// Dd = vadd(Dn, Dm)
+// Sd = vadd(Sn, Sm)
+// Dd = vsub(Dn, Dm)
+// Sd = vsub(Sn, Sm)
+// Dd = vmul(Dn, Dm)
+// Sd = vmul(Sn, Sm)
+// Dd = vmla(Dn, Dm)
+// Sd = vmla(Sn, Sm)
+// Dd = vmls(Dn, Dm)
+// Sd = vmls(Sn, Sm)
+// Dd = vdiv(Dn, Dm)
+// Sd = vdiv(Sn, Sm)
+// vcmp(Dd, Dm)
+// vcmp(Sd, Sm)
+// Dd = vsqrt(Dm)
+// Sd = vsqrt(Sm)
+// vmrs
+// vmsr
+void
+Decoder::DecodeTypeVFP(Instruction* instr)
+{
+    VERIFY((instr->TypeValue() == 7) && (instr->Bit(24) == 0x0) );
+    VERIFY(instr->Bits(11, 9) == 0x5);
+
+    if (instr->Bit(4) == 0) {
+        if (instr->Opc1Value() == 0x7) {
+            // Other data processing instructions
+            if ((instr->Opc2Value() == 0x0) && (instr->Opc3Value() == 0x1)) {
+                // vmov register to register.
+                if (instr->SzValue() == 0x1) {
+                    Format(instr, "vmov'cond.f64 'Dd, 'Dm");
+                } else {
+                    Format(instr, "vmov'cond.f32 'Sd, 'Sm");
+                }
+            } else if ((instr->Opc2Value() == 0x0) && (instr->Opc3Value() == 0x3)) {
+                // vabs
+                if (instr->SzValue() == 0x1) {
+                    Format(instr, "vabs'cond.f64 'Dd, 'Dm");
+                } else {
+                    Format(instr, "vabs'cond.f32 'Sd, 'Sm");
+                }
+            } else if ((instr->Opc2Value() == 0x1) && (instr->Opc3Value() == 0x1)) {
+                // vneg
+                if (instr->SzValue() == 0x1) {
+                    Format(instr, "vneg'cond.f64 'Dd, 'Dm");
+                } else {
+                    Format(instr, "vneg'cond.f32 'Sd, 'Sm");
+                }
+            } else if ((instr->Opc2Value() == 0x7) && (instr->Opc3Value() == 0x3)) {
+                DecodeVCVTBetweenDoubleAndSingle(instr);
+            } else if ((instr->Opc2Value() == 0x8) && (instr->Opc3Value() & 0x1)) {
+                DecodeVCVTBetweenFloatingPointAndInteger(instr);
+            } else if ((instr->Opc2Value() == 0xA) && (instr->Opc3Value() == 0x3) &&
+                       (instr->Bit(8) == 1)) {
+                // vcvt.f64.s32 Dd, Dd, #<fbits>
+                int fraction_bits = 32 - ((instr->Bits(3, 0) << 1) | instr->Bit(5));
+                Format(instr, "vcvt'cond.f64.s32 'Dd, 'Dd");
+                out_buffer_pos_ += SNPrintF(out_buffer_ + out_buffer_pos_,
+                                            ", #%d", fraction_bits);
+            } else if (((instr->Opc2Value() >> 1) == 0x6) &&
+                       (instr->Opc3Value() & 0x1)) {
+                DecodeVCVTBetweenFloatingPointAndInteger(instr);
+            } else if (((instr->Opc2Value() == 0x4) || (instr->Opc2Value() == 0x5)) &&
+                       (instr->Opc3Value() & 0x1)) {
+                DecodeVCMP(instr);
+            } else if (((instr->Opc2Value() == 0x1)) && (instr->Opc3Value() == 0x3)) {
+                if (instr->SzValue() == 0x1) {
+                    Format(instr, "vsqrt'cond.f64 'Dd, 'Dm");
+                } else {
+                    Format(instr, "vsqrt'cond.f32 'Sd, 'Sm");
+                }
+            } else if (instr->Opc3Value() == 0x0) {
+                if (instr->SzValue() == 0x1) {
+                    Format(instr, "vmov'cond.f64 'Dd, 'd");
+                } else {
+                    Unknown(instr);  // Not used by V8.
+                }
+            } else if (((instr->Opc2Value() == 0x6)) && instr->Opc3Value() == 0x3) {
+                // vrintz - round towards zero (truncate)
+                if (instr->SzValue() == 0x1) {
+                    Format(instr, "vrintz'cond.f64.f64 'Dd, 'Dm");
+                } else {
+                    Format(instr, "vrintz'cond.f32.f32 'Sd, 'Sm");
+                }
+            } else {
+                Unknown(instr);  // Not used by V8.
+            }
+        } else if (instr->Opc1Value() == 0x3) {
+            if (instr->SzValue() == 0x1) {
+                if (instr->Opc3Value() & 0x1) {
+                    Format(instr, "vsub'cond.f64 'Dd, 'Dn, 'Dm");
+                } else {
+                    Format(instr, "vadd'cond.f64 'Dd, 'Dn, 'Dm");
+                }
+            } else {
+                if (instr->Opc3Value() & 0x1) {
+                    Format(instr, "vsub'cond.f32 'Sd, 'Sn, 'Sm");
+                } else {
+                    Format(instr, "vadd'cond.f32 'Sd, 'Sn, 'Sm");
+                }
+            }
+        } else if ((instr->Opc1Value() == 0x2) && !(instr->Opc3Value() & 0x1)) {
+            if (instr->SzValue() == 0x1) {
+                Format(instr, "vmul'cond.f64 'Dd, 'Dn, 'Dm");
+            } else {
+                Format(instr, "vmul'cond.f32 'Sd, 'Sn, 'Sm");
+            }
+        } else if ((instr->Opc1Value() == 0x0) && !(instr->Opc3Value() & 0x1)) {
+            if (instr->SzValue() == 0x1) {
+                Format(instr, "vmla'cond.f64 'Dd, 'Dn, 'Dm");
+            } else {
+                Format(instr, "vmla'cond.f32 'Sd, 'Sn, 'Sm");
+            }
+        } else if ((instr->Opc1Value() == 0x0) && (instr->Opc3Value() & 0x1)) {
+            if (instr->SzValue() == 0x1) {
+                Format(instr, "vmls'cond.f64 'Dd, 'Dn, 'Dm");
+            } else {
+                Format(instr, "vmls'cond.f32 'Sd, 'Sn, 'Sm");
+            }
+        } else if ((instr->Opc1Value() == 0x4) && !(instr->Opc3Value() & 0x1)) {
+            if (instr->SzValue() == 0x1) {
+                Format(instr, "vdiv'cond.f64 'Dd, 'Dn, 'Dm");
+            } else {
+                Format(instr, "vdiv'cond.f32 'Sd, 'Sn, 'Sm");
+            }
+        } else {
+            Unknown(instr);  // Not used by V8.
+        }
+    } else {
+        if ((instr->VCValue() == 0x0) &&
+            (instr->VAValue() == 0x0)) {
+            DecodeVMOVBetweenCoreAndSinglePrecisionRegisters(instr);
+        } else if ((instr->VLValue() == 0x0) &&
+                   (instr->VCValue() == 0x1) &&
+                   (instr->Bit(23) == 0x0)) {
+            if (instr->Bit(21) == 0x0) {
+                Format(instr, "vmov'cond.32 'Dd[0], 'rt");
+            } else {
+                Format(instr, "vmov'cond.32 'Dd[1], 'rt");
+            }
+        } else if ((instr->VLValue() == 0x1) &&
+                   (instr->VCValue() == 0x1) &&
+                   (instr->Bit(23) == 0x0)) {
+            if (instr->Bit(21) == 0x0) {
+                Format(instr, "vmov'cond.32 'rt, 'Dd[0]");
+            } else {
+                Format(instr, "vmov'cond.32 'rt, 'Dd[1]");
+            }
+        } else if ((instr->VCValue() == 0x0) &&
+                   (instr->VAValue() == 0x7) &&
+                   (instr->Bits(19, 16) == 0x1)) {
+            if (instr->VLValue() == 0) {
+                if (instr->Bits(15, 12) == 0xF) {
+                    Format(instr, "vmsr'cond FPSCR, APSR");
+                } else {
+                    Format(instr, "vmsr'cond FPSCR, 'rt");
+                }
+            } else {
+                if (instr->Bits(15, 12) == 0xF) {
+                    Format(instr, "vmrs'cond APSR, FPSCR");
+                } else {
+                    Format(instr, "vmrs'cond 'rt, FPSCR");
+                }
+            }
+        }
+    }
+}
+
+
+void
+Decoder::DecodeVMOVBetweenCoreAndSinglePrecisionRegisters(Instruction* instr)
+{
+    VERIFY((instr->Bit(4) == 1) && (instr->VCValue() == 0x0) &&
+           (instr->VAValue() == 0x0));
+
+    bool to_arm_register = (instr->VLValue() == 0x1);
+
+    if (to_arm_register) {
+        Format(instr, "vmov'cond 'rt, 'Sn");
+    } else {
+        Format(instr, "vmov'cond 'Sn, 'rt");
+    }
+}
+
+
+void
+Decoder::DecodeVCMP(Instruction* instr)
+{
+    VERIFY((instr->Bit(4) == 0) && (instr->Opc1Value() == 0x7));
+    VERIFY(((instr->Opc2Value() == 0x4) || (instr->Opc2Value() == 0x5)) &&
+           (instr->Opc3Value() & 0x1));
+
+    // Comparison.
+    bool dp_operation = (instr->SzValue() == 1);
+    bool raise_exception_for_qnan = (instr->Bit(7) == 0x1);
+
+    if (dp_operation && !raise_exception_for_qnan) {
+        if (instr->Opc2Value() == 0x4) {
+            Format(instr, "vcmp'cond.f64 'Dd, 'Dm");
+        } else if (instr->Opc2Value() == 0x5) {
+            Format(instr, "vcmp'cond.f64 'Dd, #0.0");
+        } else {
+            Unknown(instr);  // invalid
+        }
+    } else if (!raise_exception_for_qnan) {
+        if (instr->Opc2Value() == 0x4) {
+            Format(instr, "vcmp'cond.f32 'Sd, 'Sm");
+        } else if (instr->Opc2Value() == 0x5) {
+            Format(instr, "vcmp'cond.f32 'Sd, #0.0");
+        } else {
+            Unknown(instr);  // invalid
+        }
+    } else {
+        Unknown(instr);  // Not used by V8.
+    }
+}
+
+
+void
+Decoder::DecodeVCVTBetweenDoubleAndSingle(Instruction* instr)
+{
+    VERIFY((instr->Bit(4) == 0) && (instr->Opc1Value() == 0x7));
+    VERIFY((instr->Opc2Value() == 0x7) && (instr->Opc3Value() == 0x3));
+
+    bool double_to_single = (instr->SzValue() == 1);
+
+    if (double_to_single) {
+        Format(instr, "vcvt'cond.f32.f64 'Sd, 'Dm");
+    } else {
+        Format(instr, "vcvt'cond.f64.f32 'Dd, 'Sm");
+    }
+}
+
+
+void
+Decoder::DecodeVCVTBetweenFloatingPointAndInteger(Instruction* instr)
+{
+    VERIFY((instr->Bit(4) == 0) && (instr->Opc1Value() == 0x7));
+    VERIFY(((instr->Opc2Value() == 0x8) && (instr->Opc3Value() & 0x1)) ||
+           (((instr->Opc2Value() >> 1) == 0x6) && (instr->Opc3Value() & 0x1)));
+
+    bool to_integer = (instr->Bit(18) == 1);
+    bool dp_operation = (instr->SzValue() == 1);
+    if (to_integer) {
+        bool unsigned_integer = (instr->Bit(16) == 0);
+
+        if (dp_operation) {
+            if (unsigned_integer) {
+                Format(instr, "vcvt'cond.u32.f64 'Sd, 'Dm");
+            } else {
+                Format(instr, "vcvt'cond.s32.f64 'Sd, 'Dm");
+            }
+        } else {
+            if (unsigned_integer) {
+                Format(instr, "vcvt'cond.u32.f32 'Sd, 'Sm");
+            } else {
+                Format(instr, "vcvt'cond.s32.f32 'Sd, 'Sm");
+            }
+        }
+    } else {
+        bool unsigned_integer = (instr->Bit(7) == 0);
+
+        if (dp_operation) {
+            if (unsigned_integer) {
+                Format(instr, "vcvt'cond.f64.u32 'Dd, 'Sm");
+            } else {
+                Format(instr, "vcvt'cond.f64.s32 'Dd, 'Sm");
+            }
+        } else {
+            if (unsigned_integer) {
+                Format(instr, "vcvt'cond.f32.u32 'Sd, 'Sm");
+            } else {
+                Format(instr, "vcvt'cond.f32.s32 'Sd, 'Sm");
+            }
+        }
+    }
+}
+
+
+// Decode Type 6 coprocessor instructions.
+// Dm = vmov(Rt, Rt2)
+// <Rt, Rt2> = vmov(Dm)
+// Ddst = MEM(Rbase + 4*offset).
+// MEM(Rbase + 4*offset) = Dsrc.
+void
+Decoder::DecodeType6CoprocessorIns(Instruction* instr)
+{
+    VERIFY(instr->TypeValue() == 6);
+
+    if (instr->CoprocessorValue() == 0xA) {
+        switch (instr->OpcodeValue()) {
+          case 0x8:
+          case 0xA:
+            if (instr->HasL()) {
+                Format(instr, "vldr'cond 'Sd, ['rn - 4*'imm08@00]");
+            } else {
+                Format(instr, "vstr'cond 'Sd, ['rn - 4*'imm08@00]");
+            }
+            break;
+          case 0xC:
+          case 0xE:
+            if (instr->HasL()) {
+                Format(instr, "vldr'cond 'Sd, ['rn + 4*'imm08@00]");
+            } else {
+                Format(instr, "vstr'cond 'Sd, ['rn + 4*'imm08@00]");
+            }
+            break;
+          case 0x4:
+          case 0x5:
+          case 0x6:
+          case 0x7:
+          case 0x9:
+          case 0xB: {
+            bool to_vfp_register = (instr->VLValue() == 0x1);
+            if (to_vfp_register) {
+                Format(instr, "vldm'cond'pu 'rn'w, {'Sd-'Sd+}");
+            } else {
+                Format(instr, "vstm'cond'pu 'rn'w, {'Sd-'Sd+}");
+            }
+            break;
+          }
+          default:
+            Unknown(instr);  // Not used by V8.
+        }
+    } else if (instr->CoprocessorValue() == 0xB) {
+        switch (instr->OpcodeValue()) {
+          case 0x2:
+            // Load and store double to two GP registers
+            if (instr->Bits(7, 6) != 0 || instr->Bit(4) != 1) {
+                Unknown(instr);  // Not used by V8.
+            } else if (instr->HasL()) {
+                Format(instr, "vmov'cond 'rt, 'rn, 'Dm");
+            } else {
+                Format(instr, "vmov'cond 'Dm, 'rt, 'rn");
+            }
+            break;
+          case 0x8:
+          case 0xA:
+            if (instr->HasL()) {
+                Format(instr, "vldr'cond 'Dd, ['rn - 4*'imm08@00]");
+            } else {
+                Format(instr, "vstr'cond 'Dd, ['rn - 4*'imm08@00]");
+            }
+            break;
+          case 0xC:
+          case 0xE:
+            if (instr->HasL()) {
+                Format(instr, "vldr'cond 'Dd, ['rn + 4*'imm08@00]");
+            } else {
+                Format(instr, "vstr'cond 'Dd, ['rn + 4*'imm08@00]");
+            }
+            break;
+          case 0x4:
+          case 0x5:
+          case 0x6:
+          case 0x7:
+          case 0x9:
+          case 0xB: {
+            bool to_vfp_register = (instr->VLValue() == 0x1);
+            if (to_vfp_register) {
+                Format(instr, "vldm'cond'pu 'rn'w, {'Dd-'Dd+}");
+            } else {
+                Format(instr, "vstm'cond'pu 'rn'w, {'Dd-'Dd+}");
+            }
+            break;
+          }
+          default:
+            Unknown(instr);  // Not used by V8.
+        }
+    } else {
+        Unknown(instr);  // Not used by V8.
+    }
+}
+
+
+void
+Decoder::DecodeSpecialCondition(Instruction* instr)
+{
+    switch (instr->SpecialValue()) {
+      case 5:
+        if ((instr->Bits(18, 16) == 0) && (instr->Bits(11, 6) == 0x28) &&
+            (instr->Bit(4) == 1)) {
+            // vmovl signed
+            if ((instr->VdValue() & 1) != 0) Unknown(instr);
+            int Vd = (instr->Bit(22) << 3) | (instr->VdValue() >> 1);
+            int Vm = (instr->Bit(5) << 4) | instr->VmValue();
+            int imm3 = instr->Bits(21, 19);
+            out_buffer_pos_ += SNPrintF(out_buffer_ + out_buffer_pos_,
+                                        "vmovl.s%d q%d, d%d", imm3*8, Vd, Vm);
+        } else {
+            Unknown(instr);
+        }
+        break;
+      case 7:
+        if ((instr->Bits(18, 16) == 0) && (instr->Bits(11, 6) == 0x28) &&
+            (instr->Bit(4) == 1)) {
+            // vmovl unsigned
+            if ((instr->VdValue() & 1) != 0) Unknown(instr);
+            int Vd = (instr->Bit(22) << 3) | (instr->VdValue() >> 1);
+            int Vm = (instr->Bit(5) << 4) | instr->VmValue();
+            int imm3 = instr->Bits(21, 19);
+            out_buffer_pos_ += SNPrintF(out_buffer_ + out_buffer_pos_,
+                                        "vmovl.u%d q%d, d%d", imm3*8, Vd, Vm);
+        } else {
+            Unknown(instr);
+        }
+        break;
+      case 8:
+        if (instr->Bits(21, 20) == 0) {
+            // vst1
+            int Vd = (instr->Bit(22) << 4) | instr->VdValue();
+            int Rn = instr->VnValue();
+            int type = instr->Bits(11, 8);
+            int size = instr->Bits(7, 6);
+            int align = instr->Bits(5, 4);
+            int Rm = instr->VmValue();
+            out_buffer_pos_ += SNPrintF(out_buffer_ + out_buffer_pos_,
+                                        "vst1.%d ", (1 << size) << 3);
+            FormatNeonList(Vd, type);
+            Print(", ");
+            FormatNeonMemory(Rn, align, Rm);
+        } else if (instr->Bits(21, 20) == 2) {
+            // vld1
+            int Vd = (instr->Bit(22) << 4) | instr->VdValue();
+            int Rn = instr->VnValue();
+            int type = instr->Bits(11, 8);
+            int size = instr->Bits(7, 6);
+            int align = instr->Bits(5, 4);
+            int Rm = instr->VmValue();
+            out_buffer_pos_ += SNPrintF(out_buffer_ + out_buffer_pos_,
+                                        "vld1.%d ", (1 << size) << 3);
+            FormatNeonList(Vd, type);
+            Print(", ");
+            FormatNeonMemory(Rn, align, Rm);
+        } else {
+            Unknown(instr);
+        }
+        break;
+      case 0xA:
+        if (instr->Bits(22, 20) == 7) {
+            const char* option = "?";
+            switch (instr->Bits(3, 0)) {
+              case  2: option = "oshst"; break;
+              case  3: option = "osh";   break;
+              case  6: option = "nshst"; break;
+              case  7: option = "nsh";   break;
+              case 10: option = "ishst"; break;
+              case 11: option = "ish";   break;
+              case 14: option = "st";    break;
+              case 15: option = "sy";    break;
+            }
+            switch (instr->Bits(7, 4)) {
+              case 4:
+                out_buffer_pos_ += SNPrintF(out_buffer_ + out_buffer_pos_,
+                                            "dsb %s", option);
+                break;
+              case 5:
+                out_buffer_pos_ += SNPrintF(out_buffer_ + out_buffer_pos_,
+                                            "dmb %s", option);
+                break;
+              default:
+                Unknown(instr);
+            }
+            break;
+        }
+        MOZ_FALLTHROUGH;
+      case 0xB:
+        if ((instr->Bits(22, 20) == 5) && (instr->Bits(15, 12) == 0xf)) {
+            int Rn = instr->Bits(19, 16);
+            int offset = instr->Bits(11, 0);
+            if (offset == 0) {
+                out_buffer_pos_ += SNPrintF(out_buffer_ + out_buffer_pos_,
+                                            "pld [r%d]", Rn);
+            } else if (instr->Bit(23) == 0) {
+                out_buffer_pos_ += SNPrintF(out_buffer_ + out_buffer_pos_,
+                                            "pld [r%d, #-%d]", Rn, offset);
+            } else {
+                out_buffer_pos_ += SNPrintF(out_buffer_ + out_buffer_pos_,
+                                            "pld [r%d, #+%d]", Rn, offset);
+            }
+        } else {
+            Unknown(instr);
+        }
+        break;
+      case 0x1D:
+        if (instr->Opc1Value() == 0x7 && instr->Bits(19, 18) == 0x2 &&
+            instr->Bits(11, 9) == 0x5 && instr->Bits(7, 6) == 0x1 &&
+            instr->Bit(4) == 0x0) {
+            // VRINTA, VRINTN, VRINTP, VRINTM (floating-point)
+            bool dp_operation = (instr->SzValue() == 1);
+            int rounding_mode = instr->Bits(17, 16);
+            switch (rounding_mode) {
+              case 0x0:
+                if (dp_operation) {
+                    Format(instr, "vrinta.f64.f64 'Dd, 'Dm");
+                } else {
+                    Unknown(instr);
+                }
+                break;
+              case 0x1:
+                if (dp_operation) {
+                    Format(instr, "vrintn.f64.f64 'Dd, 'Dm");
+                } else {
+                    Unknown(instr);
+                }
+                break;
+              case 0x2:
+                if (dp_operation) {
+                    Format(instr, "vrintp.f64.f64 'Dd, 'Dm");
+                } else {
+                    Unknown(instr);
+                }
+                break;
+              case 0x3:
+                if (dp_operation) {
+                    Format(instr, "vrintm.f64.f64 'Dd, 'Dm");
+                } else {
+                    Unknown(instr);
+                }
+                break;
+              default:
+                MOZ_CRASH();  // Case analysis is exhaustive.
+                break;
+            }
+        } else {
+            Unknown(instr);
+        }
+        break;
+      default:
+        Unknown(instr);
+        break;
+    }
+}
+
+#undef VERIFIY
+
+bool
+Decoder::IsConstantPoolAt(uint8_t* instr_ptr)
+{
+    int instruction_bits = *(reinterpret_cast<int*>(instr_ptr));
+    return (instruction_bits & kConstantPoolMarkerMask) == kConstantPoolMarker;
+}
+
+
+int
+Decoder::ConstantPoolSizeAt(uint8_t* instr_ptr)
+{
+    if (IsConstantPoolAt(instr_ptr)) {
+        int instruction_bits = *(reinterpret_cast<int*>(instr_ptr));
+        return DecodeConstantPoolLength(instruction_bits);
+    } else {
+        return -1;
+    }
+}
+
+
+// Disassemble the instruction at *instr_ptr into the output buffer.
+int
+Decoder::InstructionDecode(uint8_t* instr_ptr)
+{
+    Instruction* instr = Instruction::At(instr_ptr);
+    // Print raw instruction bytes.
+    out_buffer_pos_ += SNPrintF(out_buffer_ + out_buffer_pos_,
+                                "%08x       ",
+                                instr->InstructionBits());
+    if (instr->ConditionField() == kSpecialCondition) {
+        DecodeSpecialCondition(instr);
+        return Instruction::kInstrSize;
+    }
+    int instruction_bits = *(reinterpret_cast<int*>(instr_ptr));
+    if ((instruction_bits & kConstantPoolMarkerMask) == kConstantPoolMarker) {
+        out_buffer_pos_ += SNPrintF(out_buffer_ + out_buffer_pos_,
+                                    "constant pool begin (length %d)",
+                                    DecodeConstantPoolLength(instruction_bits));
+        return Instruction::kInstrSize;
+    } else if (instruction_bits == kCodeAgeJumpInstruction) {
+        // The code age prologue has a constant immediatly following the jump
+        // instruction.
+        Instruction* target = Instruction::At(instr_ptr + Instruction::kInstrSize);
+        DecodeType2(instr);
+        SNPrintF(out_buffer_ + out_buffer_pos_,
+                 " (0x%08x)", target->InstructionBits());
+        return 2 * Instruction::kInstrSize;
+    }
+    switch (instr->TypeValue()) {
+      case 0:
+      case 1: {
+        DecodeType01(instr);
+        break;
+      }
+      case 2: {
+        DecodeType2(instr);
+        break;
+      }
+      case 3: {
+        DecodeType3(instr);
+        break;
+      }
+      case 4: {
+        DecodeType4(instr);
+        break;
+      }
+      case 5: {
+        DecodeType5(instr);
+        break;
+      }
+      case 6: {
+        DecodeType6(instr);
+        break;
+      }
+      case 7: {
+        return DecodeType7(instr);
+      }
+      default: {
+        // The type field is 3-bits in the ARM encoding.
+        MOZ_CRASH();
+        break;
+      }
+    }
+    return Instruction::kInstrSize;
+}
+
+
+}  // namespace disasm
+
+
+#undef STRING_STARTS_WITH
+#undef VERIFY
+
+
+//------------------------------------------------------------------------------
+
+namespace disasm {
+
+
+const char*
+NameConverter::NameOfAddress(uint8_t* addr) const
+{
+    SNPrintF(tmp_buffer_, "%p", addr);
+    return tmp_buffer_.start();
+}
+
+
+const char*
+NameConverter::NameOfConstant(uint8_t* addr) const
+{
+    return NameOfAddress(addr);
+}
+
+
+const char*
+NameConverter::NameOfCPURegister(int reg) const
+{
+    return disasm::Registers::Name(reg);
+}
+
+
+const char*
+NameConverter::NameOfByteCPURegister(int reg) const
+{
+    MOZ_CRASH();  // ARM does not have the concept of a byte register
+    return "nobytereg";
+}
+
+
+const char*
+NameConverter::NameOfXMMRegister(int reg) const
+{
+    MOZ_CRASH();  // ARM does not have any XMM registers
+    return "noxmmreg";
+}
+
+
+const char*
+NameConverter::NameInCode(uint8_t* addr) const
+{
+    // The default name converter is called for unknown code. So we will not try
+    // to access any memory.
+    return "";
+}
+
+
+//------------------------------------------------------------------------------
+
+Disassembler::Disassembler(const NameConverter& converter)
+    : converter_(converter)
+{
+}
+
+
+Disassembler::~Disassembler()
+{
+}
+
+
+int
+Disassembler::InstructionDecode(V8Vector<char> buffer, uint8_t* instruction)
+{
+    Decoder d(converter_, buffer);
+    return d.InstructionDecode(instruction);
+}
+
+
+int
+Disassembler::ConstantPoolSizeAt(uint8_t* instruction)
+{
+    return Decoder::ConstantPoolSizeAt(instruction);
+}
+
+
+void
+Disassembler::Disassemble(FILE* f, uint8_t* begin, uint8_t* end)
+{
+    NameConverter converter;
+    Disassembler d(converter);
+    for (uint8_t* pc = begin; pc < end;) {
+        EmbeddedVector<char, ReasonableBufferSize> buffer;
+        buffer[0] = '\0';
+        uint8_t* prev_pc = pc;
+        pc += d.InstructionDecode(buffer, pc);
+        fprintf(
+            f, "%p    %08x      %s\n",
+            prev_pc, *reinterpret_cast<int32_t*>(prev_pc), buffer.start());
+    }
+}
+
+
+}  // namespace disasm
+}  // namespace jit
+}  // namespace js
+
+#endif // JS_DISASM_ARM
diff --git a/js/src/jit/arm/disasm/Disasm-arm.h b/js/src/jit/arm/disasm/Disasm-arm.h
new file mode 100644
index 0000000000..5421a03c77
--- /dev/null
+++ b/js/src/jit/arm/disasm/Disasm-arm.h
@@ -0,0 +1,143 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ */
+// Copyright 2007-2008 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef jit_arm_disasm_Disasm_arm_h
+#define jit_arm_disasm_Disasm_arm_h
+
+#ifdef JS_DISASM_ARM
+
+#include "mozilla/Assertions.h"
+#include "mozilla/Types.h"
+
+#include <stdio.h>
+
+namespace js {
+namespace jit {
+namespace disasm {
+
+typedef unsigned char byte;
+
+// A reasonable (ie, safe) buffer size for the disassembly of a single instruction.
+const int ReasonableBufferSize = 256;
+
+// Vector as used by the original code to allow for minimal modification.
+// Functions exactly like a character array with helper methods.
+template <typename T>
+class V8Vector {
+  public:
+    V8Vector() : start_(nullptr), length_(0) {}
+    V8Vector(T* data, int length) : start_(data), length_(length) {
+        MOZ_ASSERT(length == 0 || (length > 0 && data != nullptr));
+    }
+
+    // Returns the length of the vector.
+    int length() const { return length_; }
+
+    // Returns the pointer to the start of the data in the vector.
+    T* start() const { return start_; }
+
+    // Access individual vector elements - checks bounds in debug mode.
+    T& operator[](int index) const {
+        MOZ_ASSERT(0 <= index && index < length_);
+        return start_[index];
+    }
+
+    inline V8Vector<T> operator+(int offset) {
+        MOZ_ASSERT(offset < length_);
+        return V8Vector<T>(start_ + offset, length_ - offset);
+    }
+
+  private:
+    T* start_;
+    int length_;
+};
+
+
+template <typename T, int kSize>
+class EmbeddedVector : public V8Vector<T> {
+  public:
+    EmbeddedVector() : V8Vector<T>(buffer_, kSize) { }
+
+    explicit EmbeddedVector(T initial_value) : V8Vector<T>(buffer_, kSize) {
+        for (int i = 0; i < kSize; ++i) {
+            buffer_[i] = initial_value;
+        }
+    }
+
+    // When copying, make underlying Vector to reference our buffer.
+    EmbeddedVector(const EmbeddedVector& rhs)
+        : V8Vector<T>(rhs) {
+        MemCopy(buffer_, rhs.buffer_, sizeof(T) * kSize);
+        this->set_start(buffer_);
+    }
+
+    EmbeddedVector& operator=(const EmbeddedVector& rhs) {
+        if (this == &rhs) return *this;
+        V8Vector<T>::operator=(rhs);
+        MemCopy(buffer_, rhs.buffer_, sizeof(T) * kSize);
+        this->set_start(buffer_);
+        return *this;
+    }
+
+  private:
+    T buffer_[kSize];
+};
+
+
+// Interface and default implementation for converting addresses and
+// register-numbers to text.  The default implementation is machine
+// specific.
+class NameConverter {
+  public:
+    virtual ~NameConverter() {}
+    virtual const char* NameOfCPURegister(int reg) const;
+    virtual const char* NameOfByteCPURegister(int reg) const;
+    virtual const char* NameOfXMMRegister(int reg) const;
+    virtual const char* NameOfAddress(byte* addr) const;
+    virtual const char* NameOfConstant(byte* addr) const;
+    virtual const char* NameInCode(byte* addr) const;
+
+  protected:
+    EmbeddedVector<char, 128> tmp_buffer_;
+};
+
+
+// A generic Disassembler interface
+class Disassembler {
+  public:
+    // Caller deallocates converter.
+    explicit Disassembler(const NameConverter& converter);
+
+    virtual ~Disassembler();
+
+    // Writes one disassembled instruction into 'buffer' (0-terminated).
+    // Returns the length of the disassembled machine instruction in bytes.
+    int InstructionDecode(V8Vector<char> buffer, uint8_t* instruction);
+
+    // Returns -1 if instruction does not mark the beginning of a constant pool,
+    // or the number of entries in the constant pool beginning here.
+    int ConstantPoolSizeAt(byte* instruction);
+
+    // Write disassembly into specified file 'f' using specified NameConverter
+    // (see constructor).
+    static void Disassemble(FILE* f, uint8_t* begin, uint8_t* end);
+  private:
+    const NameConverter& converter_;
+
+    // Disallow implicit constructors.
+    Disassembler() = delete;
+    Disassembler(const Disassembler&) = delete;
+    void operator=(const Disassembler&) = delete;
+};
+
+}  // namespace disasm
+}  // namespace jit
+}  // namespace js
+
+#endif // JS_DISASM_ARM
+
+#endif  // jit_arm_disasm_Disasm_arm_h
diff --git a/js/src/jit/arm/gen-double-encoder-table.py b/js/src/jit/arm/gen-double-encoder-table.py
new file mode 100644
index 0000000000..1a208fdf40
--- /dev/null
+++ b/js/src/jit/arm/gen-double-encoder-table.py
@@ -0,0 +1,32 @@
+#!/usr/bin/env python
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+"""Generate tables of immediately-encodable VFP doubles.
+
+DOES NOT get automatically run during the build process.  If you need to
+modify this file (which is unlikely), you must re-run this script:
+
+python gen-double-encode-table.py > $(topsrcdir)/path/to/DoubleEntryTable.tbl
+"""
+
+import operator
+
+def rep(bit, count):
+    return reduce(operator.ior, [bit << c for c in range(count)])
+
+def encodeDouble(value):
+    """Generate an ARM ARM 'VFP modified immediate constant' with format:
+    aBbbbbbb bbcdefgh 000...
+
+    We will return the top 32 bits of the double; the rest are 0."""
+    assert (0 <= value) and (value <= 255)
+    a = value >> 7
+    b = (value >> 6) & 1
+    B = int(b == 0)
+    cdefgh = value & 0x3f
+    return (a << 31) | (B << 30) | (rep(b, 8) << 22) | cdefgh << 16
+
+print '/* THIS FILE IS AUTOMATICALLY GENERATED BY gen-double-encode-table.py.  */'
+for i in range(256):
+    print '  { 0x%08x, { %d, %d, 0 } },' % (encodeDouble(i), i & 0xf, i >> 4)
diff --git a/js/src/jit/arm/llvm-compiler-rt/arm/aeabi_idivmod.S b/js/src/jit/arm/llvm-compiler-rt/arm/aeabi_idivmod.S
new file mode 100644
index 0000000000..0237f2221d
--- /dev/null
+++ b/js/src/jit/arm/llvm-compiler-rt/arm/aeabi_idivmod.S
@@ -0,0 +1,27 @@
+//===-- aeabi_idivmod.S - EABI idivmod implementation ---------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "../assembly.h"
+
+// struct { int quot, int rem} __aeabi_idivmod(int numerator, int denominator) {
+//   int rem, quot;
+//   quot = __divmodsi4(numerator, denominator, &rem);
+//   return {quot, rem};
+// }
+
+        .syntax unified
+        .align 2
+DEFINE_COMPILERRT_FUNCTION(__aeabi_idivmod)
+        push    { lr }
+        sub     sp, sp, #4
+        mov     r2, sp
+        bl      SYMBOL_NAME(__divmodsi4)
+        ldr     r1, [sp]
+        add     sp, sp, #4
+        pop     { pc }
diff --git a/js/src/jit/arm/llvm-compiler-rt/arm/aeabi_uidivmod.S b/js/src/jit/arm/llvm-compiler-rt/arm/aeabi_uidivmod.S
new file mode 100644
index 0000000000..f7e1d2ebed
--- /dev/null
+++ b/js/src/jit/arm/llvm-compiler-rt/arm/aeabi_uidivmod.S
@@ -0,0 +1,28 @@
+//===-- aeabi_uidivmod.S - EABI uidivmod implementation -------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "../assembly.h"
+
+// struct { unsigned quot, unsigned rem}
+//        __aeabi_uidivmod(unsigned numerator, unsigned denominator) {
+//   unsigned rem, quot;
+//   quot = __udivmodsi4(numerator, denominator, &rem);
+//   return {quot, rem};
+// }
+
+        .syntax unified
+        .align 2
+DEFINE_COMPILERRT_FUNCTION(__aeabi_uidivmod)
+        push    { lr }
+        sub     sp, sp, #4
+        mov     r2, sp
+        bl      SYMBOL_NAME(__udivmodsi4)
+        ldr     r1, [sp]
+        add     sp, sp, #4
+        pop     { pc }
diff --git a/js/src/jit/arm/llvm-compiler-rt/assembly.h b/js/src/jit/arm/llvm-compiler-rt/assembly.h
new file mode 100644
index 0000000000..83bed12335
--- /dev/null
+++ b/js/src/jit/arm/llvm-compiler-rt/assembly.h
@@ -0,0 +1,70 @@
+/* ===-- assembly.h - compiler-rt assembler support macros -----------------===
+ *
+ *                     The LLVM Compiler Infrastructure
+ *
+ * This file is dual licensed under the MIT and the University of Illinois Open
+ * Source Licenses. See LICENSE.TXT for details.
+ *
+ * ===----------------------------------------------------------------------===
+ *
+ * This file defines macros for use in compiler-rt assembler source.
+ * This file is not part of the interface of this library.
+ *
+ * ===----------------------------------------------------------------------===
+ */
+
+#ifndef COMPILERRT_ASSEMBLY_H
+#define COMPILERRT_ASSEMBLY_H
+
+#if defined(__POWERPC__) || defined(__powerpc__) || defined(__ppc__)
+#define SEPARATOR @
+#else
+#define SEPARATOR ;
+#endif
+
+#if defined(__APPLE__)
+#define HIDDEN_DIRECTIVE .private_extern
+#define LOCAL_LABEL(name) L_##name
+#else
+#define HIDDEN_DIRECTIVE .hidden
+#define LOCAL_LABEL(name) .L_##name
+#endif
+
+#define GLUE2(a, b) a ## b
+#define GLUE(a, b) GLUE2(a, b)
+#define SYMBOL_NAME(name) GLUE(__USER_LABEL_PREFIX__, name)
+
+#ifdef VISIBILITY_HIDDEN
+#define DECLARE_SYMBOL_VISIBILITY(name)                    \
+  HIDDEN_DIRECTIVE SYMBOL_NAME(name) SEPARATOR
+#else
+#define DECLARE_SYMBOL_VISIBILITY(name)
+#endif
+
+#define DEFINE_COMPILERRT_FUNCTION(name)                   \
+  .globl SYMBOL_NAME(name) SEPARATOR                       \
+  DECLARE_SYMBOL_VISIBILITY(name)                          \
+  SYMBOL_NAME(name):
+
+#define DEFINE_COMPILERRT_PRIVATE_FUNCTION(name)           \
+  .globl SYMBOL_NAME(name) SEPARATOR                       \
+  HIDDEN_DIRECTIVE SYMBOL_NAME(name) SEPARATOR             \
+  SYMBOL_NAME(name):
+
+#define DEFINE_COMPILERRT_PRIVATE_FUNCTION_UNMANGLED(name) \
+  .globl name SEPARATOR                                    \
+  HIDDEN_DIRECTIVE name SEPARATOR                          \
+  name:
+
+#define DEFINE_COMPILERRT_FUNCTION_ALIAS(name, target)     \
+  .globl SYMBOL_NAME(name) SEPARATOR                       \
+  .set SYMBOL_NAME(name), SYMBOL_NAME(target) SEPARATOR
+
+#if defined (__ARM_EABI__)
+# define DEFINE_AEABI_FUNCTION_ALIAS(aeabi_name, name)      \
+  DEFINE_COMPILERRT_FUNCTION_ALIAS(aeabi_name, name)
+#else
+# define DEFINE_AEABI_FUNCTION_ALIAS(aeabi_name, name)
+#endif
+
+#endif /* COMPILERRT_ASSEMBLY_H */