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
|
// Copyright 2010 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.
// The routines exported by this module are subtle. If you use them, even if
// you get the code right, it will depend on careful reasoning about atomicity
// and memory ordering; it will be less readable, and harder to maintain. If
// you plan to use these routines, you should have a good reason, such as solid
// evidence that performance would otherwise suffer, or there being no
// alternative. You should assume only properties explicitly guaranteed by the
// specifications in this file. You are almost certainly _not_ writing code
// just for the x86; if you assume x86 semantics, x86 hardware bugs and
// implementations on other archtectures will cause your code to break. If you
// do not know what you are doing, avoid these routines, and use a Mutex.
//
// It is incorrect to make direct assignments to/from an atomic variable.
// You should use one of the Load or Store routines. The Relaxed versions
// are provided when no fences are needed:
// Relaxed_Store()
// Relaxed_Load()
// Although there are currently no compiler enforcement, you are encouraged
// to use these.
//
#ifndef V8_BASE_ATOMICOPS_H_
#define V8_BASE_ATOMICOPS_H_
#include <stdint.h>
// Small C++ header which defines implementation specific macros used to
// identify the STL implementation.
// - libc++: captures __config for _LIBCPP_VERSION
// - libstdc++: captures bits/c++config.h for __GLIBCXX__
#include <cstddef>
#include "src/base/base-export.h"
#include "src/base/build_config.h"
#if defined(V8_OS_STARBOARD)
#include "starboard/atomic.h"
#if SB_API_VERSION < 10
#error Your version of Starboard must support SbAtomic8 in order to use V8.
#endif // SB_API_VERSION < 10
#endif // V8_OS_STARBOARD
namespace v8 {
namespace base {
#ifdef V8_OS_STARBOARD
using Atomic8 = SbAtomic8;
using Atomic16 = int16_t;
using Atomic32 = SbAtomic32;
#if SB_IS_64_BIT
using Atomic64 = SbAtomic64;
#endif
#else
using Atomic8 = char;
using Atomic16 = int16_t;
using Atomic32 = int32_t;
#if defined(V8_HOST_ARCH_64_BIT)
// We need to be able to go between Atomic64 and AtomicWord implicitly. This
// means Atomic64 and AtomicWord should be the same type on 64-bit.
#if defined(__ILP32__)
using Atomic64 = int64_t;
#else
using Atomic64 = intptr_t;
#endif // defined(__ILP32__)
#endif // defined(V8_HOST_ARCH_64_BIT)
#endif // V8_OS_STARBOARD
// Use AtomicWord for a machine-sized pointer. It will use the Atomic32 or
// Atomic64 routines below, depending on your architecture.
#if defined(V8_OS_STARBOARD)
using AtomicWord = SbAtomicPtr;
#else
using AtomicWord = intptr_t;
#endif
// Atomically execute:
// result = *ptr;
// if (result == old_value)
// *ptr = new_value;
// return result;
//
// I.e. replace |*ptr| with |new_value| if |*ptr| used to be |old_value|.
// Always return the value of |*ptr| before the operation.
// Acquire, Relaxed, Release correspond to standard C++ memory orders.
Atomic8 Relaxed_CompareAndSwap(volatile Atomic8* ptr, Atomic8 old_value,
Atomic8 new_value);
Atomic16 Relaxed_CompareAndSwap(volatile Atomic16* ptr, Atomic16 old_value,
Atomic16 new_value);
Atomic32 Acquire_CompareAndSwap(volatile Atomic32* ptr, Atomic32 old_value,
Atomic32 new_value);
Atomic32 AcquireRelease_CompareAndSwap(volatile Atomic32* ptr,
Atomic32 old_value, Atomic32 new_value);
Atomic32 Relaxed_CompareAndSwap(volatile Atomic32* ptr, Atomic32 old_value,
Atomic32 new_value);
Atomic32 Release_CompareAndSwap(volatile Atomic32* ptr, Atomic32 old_value,
Atomic32 new_value);
#ifdef V8_HOST_ARCH_64_BIT
Atomic64 Acquire_CompareAndSwap(volatile Atomic64* ptr, Atomic64 old_value,
Atomic64 new_value);
Atomic64 AcquireRelease_CompareAndSwap(volatile Atomic64* ptr,
Atomic64 old_value, Atomic64 new_value);
Atomic64 Relaxed_CompareAndSwap(volatile Atomic64* ptr, Atomic64 old_value,
Atomic64 new_value);
Atomic64 Release_CompareAndSwap(volatile Atomic64* ptr, Atomic64 old_value,
Atomic64 new_value);
#endif // V8_HOST_ARCH_64_BIT
// Atomically store new_value into |*ptr|, returning the previous value held in
// |*ptr|.
Atomic32 Relaxed_AtomicExchange(volatile Atomic32* ptr, Atomic32 new_value);
#ifdef V8_HOST_ARCH_64_BIT
Atomic64 Relaxed_AtomicExchange(volatile Atomic64* ptr, Atomic64 new_value);
#endif // V8_HOST_ARCH_64_BIT
// Atomically increment |*ptr| by |increment|. Returns the new value of
// |*ptr| with the increment applied.
Atomic32 Relaxed_AtomicIncrement(volatile Atomic32* ptr, Atomic32 increment);
#ifdef V8_HOST_ARCH_64_BIT
Atomic64 Relaxed_AtomicIncrement(volatile Atomic64* ptr, Atomic64 increment);
#endif // V8_HOST_ARCH_64_BIT
void SeqCst_MemoryFence();
void Relaxed_Store(volatile Atomic8* ptr, Atomic8 value);
void Relaxed_Store(volatile Atomic16* ptr, Atomic16 value);
void Relaxed_Store(volatile Atomic32* ptr, Atomic32 value);
void Release_Store(volatile Atomic32* ptr, Atomic32 value);
#ifdef V8_HOST_ARCH_64_BIT
void Relaxed_Store(volatile Atomic64* ptr, Atomic64 value);
void Release_Store(volatile Atomic64* ptr, Atomic64 value);
#endif // V8_HOST_ARCH_64_BIT
Atomic8 Relaxed_Load(volatile const Atomic8* ptr);
Atomic16 Relaxed_Load(volatile const Atomic16* ptr);
Atomic32 Relaxed_Load(volatile const Atomic32* ptr);
Atomic32 Acquire_Load(volatile const Atomic32* ptr);
#ifdef V8_HOST_ARCH_64_BIT
Atomic64 Relaxed_Load(volatile const Atomic64* ptr);
Atomic64 Acquire_Load(volatile const Atomic64* ptr);
#endif // V8_HOST_ARCH_64_BIT
} // namespace base
} // namespace v8
#if defined(V8_OS_WIN) || defined(V8_OS_STARBOARD)
#include "src/base/atomicops_internals_std.h"
#else
// TODO(ulan): Switch to std version after performance regression with Wheezy
// sysroot is no longer relevant. Debian Wheezy LTS ends on 31st of May 2018.
#include "src/base/atomicops_internals_portable.h"
#endif
// On some platforms we need additional declarations to make
// AtomicWord compatible with our other Atomic* types.
#if defined(V8_OS_MACOSX) || defined(V8_OS_OPENBSD) || defined(V8_OS_AIX)
#include "src/base/atomicops_internals_atomicword_compat.h"
#endif
#endif // V8_BASE_ATOMICOPS_H_
|
