1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
|
/* -*- 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/. */
/* 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__)
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.
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);
}
inline void
js::jit::AtomicOperations::fenceSeqCst()
{
__atomic_thread_fence(__ATOMIC_SEQ_CST);
}
template<typename T>
inline T
js::jit::AtomicOperations::loadSeqCst(T* addr)
{
MOZ_ASSERT(sizeof(T) < 8 || isLockfree8());
T v;
__atomic_load(addr, &v, __ATOMIC_SEQ_CST);
return v;
}
template<typename T>
inline void
js::jit::AtomicOperations::storeSeqCst(T* addr, T val)
{
MOZ_ASSERT(sizeof(T) < 8 || isLockfree8());
__atomic_store(addr, &val, __ATOMIC_SEQ_CST);
}
template<typename T>
inline T
js::jit::AtomicOperations::exchangeSeqCst(T* addr, T val)
{
MOZ_ASSERT(sizeof(T) < 8 || isLockfree8());
T v;
__atomic_exchange(addr, &val, &v, __ATOMIC_SEQ_CST);
return v;
}
template<typename T>
inline T
js::jit::AtomicOperations::compareExchangeSeqCst(T* addr, T oldval, T newval)
{
MOZ_ASSERT(sizeof(T) < 8 || isLockfree8());
__atomic_compare_exchange(addr, &oldval, &newval, false, __ATOMIC_SEQ_CST, __ATOMIC_SEQ_CST);
return oldval;
}
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");
return __atomic_fetch_add(addr, val, __ATOMIC_SEQ_CST);
}
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");
return __atomic_fetch_sub(addr, val, __ATOMIC_SEQ_CST);
}
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");
return __atomic_fetch_and(addr, val, __ATOMIC_SEQ_CST);
}
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");
return __atomic_fetch_or(addr, val, __ATOMIC_SEQ_CST);
}
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");
return __atomic_fetch_xor(addr, val, __ATOMIC_SEQ_CST);
}
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)
{
uint32_t zero = 0;
uint32_t one = 1;
while (!__atomic_compare_exchange(&spinlock, &zero, &one, false, __ATOMIC_ACQUIRE, __ATOMIC_ACQUIRE)) {
zero = 0;
continue;
}
}
template<size_t nbytes>
inline void
js::jit::RegionLock::release(void* addr)
{
MOZ_ASSERT(AtomicOperations::loadSeqCst(&spinlock) == 1, "releasing unlocked region lock");
uint32_t zero = 0;
__atomic_store(&spinlock, &zero, __ATOMIC_SEQ_CST);
}
#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
|
