path: root/js/src/vm/SPSProfiler.cpp

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
 * 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 "vm/SPSProfiler.h"

#include "mozilla/DebugOnly.h"

#include "jsnum.h"
#include "jsprf.h"
#include "jsscript.h"

#include "jit/BaselineFrame.h"
#include "jit/BaselineJIT.h"
#include "jit/JitcodeMap.h"
#include "jit/JitFrameIterator.h"
#include "jit/JitFrames.h"
#include "vm/StringBuffer.h"

using namespace js;

using mozilla::DebugOnly;

SPSProfiler::SPSProfiler(JSRuntime* rt)
  : rt(rt),
    strings(mutexid::SPSProfilerStrings),
    stack_(nullptr),
    size_(nullptr),
    max_(0),
    slowAssertions(false),
    enabled_(false),
    eventMarker_(nullptr)
{
    MOZ_ASSERT(rt != nullptr);
}

bool
SPSProfiler::init()
{
    auto locked = strings.lock();
    if (!locked->init())
        return false;

    return true;
}

void
SPSProfiler::setProfilingStack(ProfileEntry* stack, uint32_t* size, uint32_t max)
{
    MOZ_ASSERT_IF(size_ && *size_ != 0, !enabled());
    MOZ_ASSERT(strings.lock()->initialized());

    stack_ = stack;
    size_  = size;
    max_   = max;
}

void
SPSProfiler::setEventMarker(void (*fn)(const char*))
{
    eventMarker_ = fn;
}

void
SPSProfiler::enable(bool enabled)
{
    MOZ_ASSERT(installed());

    if (enabled_ == enabled)
        return;

    /*
     * Ensure all future generated code will be instrumented, or that all
     * currently instrumented code is discarded
     */
    ReleaseAllJITCode(rt->defaultFreeOp());

    // This function is called when the Gecko profiler makes a new TableTicker
    // (and thus, a new circular buffer). Set all current entries in the
    // JitcodeGlobalTable as expired and reset the buffer generation and lap
    // count.
    if (rt->hasJitRuntime() && rt->jitRuntime()->hasJitcodeGlobalTable())
        rt->jitRuntime()->getJitcodeGlobalTable()->setAllEntriesAsExpired(rt);
    rt->resetProfilerSampleBufferGen();
    rt->resetProfilerSampleBufferLapCount();

    // Ensure that lastProfilingFrame is null before 'enabled' becomes true.
    if (rt->jitActivation) {
        rt->jitActivation->setLastProfilingFrame(nullptr);
        rt->jitActivation->setLastProfilingCallSite(nullptr);
    }

    enabled_ = enabled;

    /* Toggle SPS-related jumps on baseline jitcode.
     * The call to |ReleaseAllJITCode| above will release most baseline jitcode, but not
     * jitcode for scripts with active frames on the stack.  These scripts need to have
     * their profiler state toggled so they behave properly.
     */
    jit::ToggleBaselineProfiling(rt, enabled);

    /* Update lastProfilingFrame to point to the top-most JS jit-frame currently on
     * stack.
     */
    if (rt->jitActivation) {
        // Walk through all activations, and set their lastProfilingFrame appropriately.
        if (enabled) {
            void* lastProfilingFrame = GetTopProfilingJitFrame(rt->jitTop);
            jit::JitActivation* jitActivation = rt->jitActivation;
            while (jitActivation) {
                jitActivation->setLastProfilingFrame(lastProfilingFrame);
                jitActivation->setLastProfilingCallSite(nullptr);

                lastProfilingFrame = GetTopProfilingJitFrame(jitActivation->prevJitTop());
                jitActivation = jitActivation->prevJitActivation();
            }
        } else {
            jit::JitActivation* jitActivation = rt->jitActivation;
            while (jitActivation) {
                jitActivation->setLastProfilingFrame(nullptr);
                jitActivation->setLastProfilingCallSite(nullptr);
                jitActivation = jitActivation->prevJitActivation();
            }
        }
    }
}

/* Lookup the string for the function/script, creating one if necessary */
const char*
SPSProfiler::profileString(JSScript* script, JSFunction* maybeFun)
{
    auto locked = strings.lock();
    MOZ_ASSERT(locked->initialized());

    ProfileStringMap::AddPtr s = locked->lookupForAdd(script);

    if (!s) {
        auto str = allocProfileString(script, maybeFun);
        if (!str || !locked->add(s, script, mozilla::Move(str)))
            return nullptr;
    }

    return s->value().get();
}

void
SPSProfiler::onScriptFinalized(JSScript* script)
{
    /*
     * This function is called whenever a script is destroyed, regardless of
     * whether profiling has been turned on, so don't invoke a function on an
     * invalid hash set. Also, even if profiling was enabled but then turned
     * off, we still want to remove the string, so no check of enabled() is
     * done.
     */
    auto locked = strings.lock();
    if (!locked->initialized())
        return;
    if (ProfileStringMap::Ptr entry = locked->lookup(script))
        locked->remove(entry);
}

void
SPSProfiler::markEvent(const char* event)
{
    MOZ_ASSERT(enabled());
    if (eventMarker_) {
        JS::AutoSuppressGCAnalysis nogc;
        eventMarker_(event);
    }
}

bool
SPSProfiler::enter(JSContext* cx, JSScript* script, JSFunction* maybeFun)
{
    const char* str = profileString(script, maybeFun);
    if (str == nullptr) {
        ReportOutOfMemory(cx);
        return false;
    }

#ifdef DEBUG
    // In debug builds, assert the JS pseudo frames already on the stack
    // have a non-null pc. Only look at the top frames to avoid quadratic
    // behavior.
    if (*size_ > 0 && *size_ - 1 < max_) {
        size_t start = (*size_ > 4) ? *size_ - 4 : 0;
        for (size_t i = start; i < *size_ - 1; i++)
            MOZ_ASSERT_IF(stack_[i].isJs(), stack_[i].pc() != nullptr);
    }
#endif

    push(str, nullptr, script, script->code(), /* copy = */ true);
    return true;
}

void
SPSProfiler::exit(JSScript* script, JSFunction* maybeFun)
{
    pop();

#ifdef DEBUG
    /* Sanity check to make sure push/pop balanced */
    if (*size_ < max_) {
        const char* str = profileString(script, maybeFun);
        /* Can't fail lookup because we should already be in the set */
        MOZ_ASSERT(str != nullptr);

        // Bug 822041
        if (!stack_[*size_].isJs()) {
            fprintf(stderr, "--- ABOUT TO FAIL ASSERTION ---\n");
            fprintf(stderr, " stack=%p size=%d/%d\n", (void*) stack_, *size_, max_);
            for (int32_t i = *size_; i >= 0; i--) {
                if (stack_[i].isJs())
                    fprintf(stderr, "  [%d] JS %s\n", i, stack_[i].label());
                else
                    fprintf(stderr, "  [%d] C line %d %s\n", i, stack_[i].line(), stack_[i].label());
            }
        }

        MOZ_ASSERT(stack_[*size_].isJs());
        MOZ_ASSERT(stack_[*size_].script() == script);
        MOZ_ASSERT(strcmp((const char*) stack_[*size_].label(), str) == 0);
        stack_[*size_].setLabel(nullptr);
        stack_[*size_].setPC(nullptr);
    }
#endif
}

void
SPSProfiler::beginPseudoJS(const char* string, void* sp)
{
    /* these operations cannot be re-ordered, so volatile-ize operations */
    volatile ProfileEntry* stack = stack_;
    volatile uint32_t* size = size_;
    uint32_t current = *size;

    MOZ_ASSERT(installed());
    if (current < max_) {
        stack[current].setLabel(string);
        stack[current].initCppFrame(sp, 0);
        stack[current].setFlag(ProfileEntry::BEGIN_PSEUDO_JS);
    }
    *size = current + 1;
}

void
SPSProfiler::push(const char* string, void* sp, JSScript* script, jsbytecode* pc, bool copy,
                  ProfileEntry::Category category)
{
    MOZ_ASSERT_IF(sp != nullptr, script == nullptr && pc == nullptr);
    MOZ_ASSERT_IF(sp == nullptr, script != nullptr && pc != nullptr);

    /* these operations cannot be re-ordered, so volatile-ize operations */
    volatile ProfileEntry* stack = stack_;
    volatile uint32_t* size = size_;
    uint32_t current = *size;

    MOZ_ASSERT(installed());
    if (current < max_) {
        volatile ProfileEntry& entry = stack[current];

        if (sp != nullptr) {
            entry.initCppFrame(sp, 0);
            MOZ_ASSERT(entry.flags() == js::ProfileEntry::IS_CPP_ENTRY);
        }
        else {
            entry.initJsFrame(script, pc);
            MOZ_ASSERT(entry.flags() == 0);
        }

        entry.setLabel(string);
        entry.setCategory(category);

        // Track if mLabel needs a copy.
        if (copy)
            entry.setFlag(js::ProfileEntry::FRAME_LABEL_COPY);
        else
            entry.unsetFlag(js::ProfileEntry::FRAME_LABEL_COPY);
    }
    *size = current + 1;
}

void
SPSProfiler::pop()
{
    MOZ_ASSERT(installed());
    MOZ_ASSERT(*size_ > 0);
    (*size_)--;
}

/*
 * Serializes the script/function pair into a "descriptive string" which is
 * allowed to fail. This function cannot trigger a GC because it could finalize
 * some scripts, resize the hash table of profile strings, and invalidate the
 * AddPtr held while invoking allocProfileString.
 */
UniqueChars
SPSProfiler::allocProfileString(JSScript* script, JSFunction* maybeFun)
{
    // Note: this profiler string is regexp-matched by
    // devtools/client/profiler/cleopatra/js/parserWorker.js.

    // Get the function name, if any.
    JSAtom* atom = maybeFun ? maybeFun->displayAtom() : nullptr;

    // Get the script filename, if any, and its length.
    const char* filename = script->filename();
    if (filename == nullptr)
        filename = "<unknown>";
    size_t lenFilename = strlen(filename);

    // Get the line number and its length as a string.
    uint64_t lineno = script->lineno();
    size_t lenLineno = 1;
    for (uint64_t i = lineno; i /= 10; lenLineno++);

    // Determine the required buffer size.
    size_t len = lenFilename + lenLineno + 1; // +1 for the ":" separating them.
    if (atom) {
        len += JS::GetDeflatedUTF8StringLength(atom) + 3; // +3 for the " (" and ")" it adds.
    }

    // Allocate the buffer.
    UniqueChars cstr(js_pod_malloc<char>(len + 1));
    if (!cstr)
        return nullptr;

    // Construct the descriptive string.
    DebugOnly<size_t> ret;
    if (atom) {
        UniqueChars atomStr = StringToNewUTF8CharsZ(nullptr, *atom);
        if (!atomStr)
            return nullptr;

        ret = snprintf(cstr.get(), len + 1, "%s (%s:%" PRIu64 ")", atomStr.get(), filename, lineno);
    } else {
        ret = snprintf(cstr.get(), len + 1, "%s:%" PRIu64, filename, lineno);
    }

    MOZ_ASSERT(ret == len, "Computed length should match actual length!");

    return cstr;
}

void
SPSProfiler::trace(JSTracer* trc)
{
    if (stack_) {
        size_t limit = Min(*size_, max_);
        for (size_t i = 0; i < limit; i++)
            stack_[i].trace(trc);
    }
}

void
SPSProfiler::fixupStringsMapAfterMovingGC()
{
    auto locked = strings.lock();
    if (!locked->initialized())
        return;

    for (ProfileStringMap::Enum e(locked.get()); !e.empty(); e.popFront()) {
        JSScript* script = e.front().key();
        if (IsForwarded(script)) {
            script = Forwarded(script);
            e.rekeyFront(script);
        }
    }
}

#ifdef JSGC_HASH_TABLE_CHECKS
void
SPSProfiler::checkStringsMapAfterMovingGC()
{
    auto locked = strings.lock();
    if (!locked->initialized())
        return;

    for (auto r = locked->all(); !r.empty(); r.popFront()) {
        JSScript* script = r.front().key();
        CheckGCThingAfterMovingGC(script);
        auto ptr = locked->lookup(script);
        MOZ_RELEASE_ASSERT(ptr.found() && &*ptr == &r.front());
    }
}
#endif

void
ProfileEntry::trace(JSTracer* trc)
{
    if (isJs()) {
        JSScript* s = rawScript();
        TraceNullableRoot(trc, &s, "ProfileEntry script");
        spOrScript = s;
    }
}

SPSEntryMarker::SPSEntryMarker(JSRuntime* rt,
                               JSScript* script
                               MOZ_GUARD_OBJECT_NOTIFIER_PARAM_IN_IMPL)
    : profiler(&rt->spsProfiler)
{
    MOZ_GUARD_OBJECT_NOTIFIER_INIT;
    if (!profiler->installed()) {
        profiler = nullptr;
        return;
    }
    size_before = *profiler->size_;
    // We want to push a CPP frame so the profiler can correctly order JS and native stacks.
    profiler->beginPseudoJS("js::RunScript", this);
    profiler->push("js::RunScript", nullptr, script, script->code(), /* copy = */ false);
}

SPSEntryMarker::~SPSEntryMarker()
{
    if (profiler == nullptr)
        return;

    profiler->pop();
    profiler->endPseudoJS();
    MOZ_ASSERT(size_before == *profiler->size_);
}

AutoSPSEntry::AutoSPSEntry(JSRuntime* rt, const char* label, ProfileEntry::Category category
                           MOZ_GUARD_OBJECT_NOTIFIER_PARAM_IN_IMPL)
    : profiler_(&rt->spsProfiler)
{
    MOZ_GUARD_OBJECT_NOTIFIER_INIT;
    if (!profiler_->installed()) {
        profiler_ = nullptr;
        return;
    }
    sizeBefore_ = *profiler_->size_;
    profiler_->beginPseudoJS(label, this);
    profiler_->push(label, this, nullptr, nullptr, /* copy = */ false, category);
}

AutoSPSEntry::~AutoSPSEntry()
{
    if (!profiler_)
        return;

    profiler_->pop();
    profiler_->endPseudoJS();
    MOZ_ASSERT(sizeBefore_ == *profiler_->size_);
}

SPSBaselineOSRMarker::SPSBaselineOSRMarker(JSRuntime* rt, bool hasSPSFrame
                                           MOZ_GUARD_OBJECT_NOTIFIER_PARAM_IN_IMPL)
    : profiler(&rt->spsProfiler)
{
    MOZ_GUARD_OBJECT_NOTIFIER_INIT;
    if (!hasSPSFrame || !profiler->enabled() ||
        profiler->size() >= profiler->maxSize())
    {
        profiler = nullptr;
        return;
    }

    size_before = profiler->size();
    if (profiler->size() == 0)
        return;

    ProfileEntry& entry = profiler->stack()[profiler->size() - 1];
    MOZ_ASSERT(entry.isJs());
    entry.setOSR();
}

SPSBaselineOSRMarker::~SPSBaselineOSRMarker()
{
    if (profiler == nullptr)
        return;

    MOZ_ASSERT(size_before == *profiler->size_);
    if (profiler->size() == 0)
        return;

    ProfileEntry& entry = profiler->stack()[profiler->size() - 1];
    MOZ_ASSERT(entry.isJs());
    entry.unsetOSR();
}

JS_PUBLIC_API(JSScript*)
ProfileEntry::script() const volatile
{
    MOZ_ASSERT(isJs());
    auto script = reinterpret_cast<JSScript*>(spOrScript);
    if (!script)
        return nullptr;

    // If profiling is supressed then we can't trust the script pointers to be
    // valid as they could be in the process of being moved by a compacting GC
    // (although it's still OK to get the runtime from them).
    JSRuntime* rt = script->zoneFromAnyThread()->runtimeFromAnyThread();
    if (!rt->isProfilerSamplingEnabled())
        return nullptr;

    MOZ_ASSERT(!IsForwarded(script));
    return script;
}

JS_FRIEND_API(jsbytecode*)
ProfileEntry::pc() const volatile
{
    MOZ_ASSERT(isJs());
    if (lineOrPcOffset == NullPCOffset)
        return nullptr;

    JSScript* script = this->script();
    return script ? script->offsetToPC(lineOrPcOffset) : nullptr;
}

JS_FRIEND_API(void)
ProfileEntry::setPC(jsbytecode* pc) volatile
{
    MOZ_ASSERT(isJs());
    JSScript* script = this->script();
    MOZ_ASSERT(script); // This should not be called while profiling is suppressed.
    lineOrPcOffset = pc == nullptr ? NullPCOffset : script->pcToOffset(pc);
}

JS_FRIEND_API(void)
js::SetContextProfilingStack(JSContext* cx, ProfileEntry* stack, uint32_t* size, uint32_t max)
{
    cx->spsProfiler.setProfilingStack(stack, size, max);
}

JS_FRIEND_API(void)
js::EnableContextProfilingStack(JSContext* cx, bool enabled)
{
    cx->spsProfiler.enable(enabled);
}

JS_FRIEND_API(void)
js::RegisterContextProfilingEventMarker(JSContext* cx, void (*fn)(const char*))
{
    MOZ_ASSERT(cx->spsProfiler.enabled());
    cx->spsProfiler.setEventMarker(fn);
}

JS_FRIEND_API(jsbytecode*)
js::ProfilingGetPC(JSContext* cx, JSScript* script, void* ip)
{
    return cx->spsProfiler.ipToPC(script, size_t(ip));
}

AutoSuppressProfilerSampling::AutoSuppressProfilerSampling(JSContext* cx
                                                           MOZ_GUARD_OBJECT_NOTIFIER_PARAM_IN_IMPL)
  : rt_(cx->runtime()),
    previouslyEnabled_(rt_->isProfilerSamplingEnabled())
{
    MOZ_GUARD_OBJECT_NOTIFIER_INIT;
    if (previouslyEnabled_)
        rt_->disableProfilerSampling();
}

AutoSuppressProfilerSampling::AutoSuppressProfilerSampling(JSRuntime* rt
                                                           MOZ_GUARD_OBJECT_NOTIFIER_PARAM_IN_IMPL)
  : rt_(rt),
    previouslyEnabled_(rt_->isProfilerSamplingEnabled())
{
    MOZ_GUARD_OBJECT_NOTIFIER_INIT;
    if (previouslyEnabled_)
        rt_->disableProfilerSampling();
}

AutoSuppressProfilerSampling::~AutoSuppressProfilerSampling()
{
    if (previouslyEnabled_)
        rt_->enableProfilerSampling();
}

void*
js::GetTopProfilingJitFrame(uint8_t* exitFramePtr)
{
    // For null exitFrame, there is no previous exit frame, just return.
    if (!exitFramePtr)
        return nullptr;

    jit::JitProfilingFrameIterator iter(exitFramePtr);
    MOZ_ASSERT(!iter.done());
    return iter.fp();
}