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2e362c74 | 1 | // Support for atomic operations -*- C++ -*- |
2c5d0ae8 | 2 | |
7adcbafe | 3 | // Copyright (C) 2004-2022 Free Software Foundation, Inc. |
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4 | // |
5 | // This file is part of the GNU ISO C++ Library. This library is free | |
6 | // software; you can redistribute it and/or modify it under the | |
7 | // terms of the GNU General Public License as published by the | |
748086b7 | 8 | // Free Software Foundation; either version 3, or (at your option) |
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9 | // any later version. |
10 | ||
11 | // This library is distributed in the hope that it will be useful, | |
12 | // but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | // GNU General Public License for more details. | |
15 | ||
748086b7 JJ |
16 | // Under Section 7 of GPL version 3, you are granted additional |
17 | // permissions described in the GCC Runtime Library Exception, version | |
18 | // 3.1, as published by the Free Software Foundation. | |
2c5d0ae8 | 19 | |
748086b7 JJ |
20 | // You should have received a copy of the GNU General Public License and |
21 | // a copy of the GCC Runtime Library Exception along with this program; | |
22 | // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see | |
23 | // <http://www.gnu.org/licenses/>. | |
2c5d0ae8 | 24 | |
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25 | /** @file ext/atomicity.h |
26 | * This file is a GNU extension to the Standard C++ Library. | |
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27 | */ |
28 | ||
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29 | #ifndef _GLIBCXX_ATOMICITY_H |
30 | #define _GLIBCXX_ATOMICITY_H 1 | |
31 | ||
aeb1f2be PC |
32 | #pragma GCC system_header |
33 | ||
3cbc7af0 | 34 | #include <bits/c++config.h> |
b7ee72de | 35 | #include <bits/gthr.h> |
2c5d0ae8 | 36 | #include <bits/atomic_word.h> |
e6923541 JW |
37 | #if __has_include(<sys/single_threaded.h>) |
38 | # include <sys/single_threaded.h> | |
39 | #endif | |
3cbc7af0 | 40 | |
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41 | namespace __gnu_cxx _GLIBCXX_VISIBILITY(default) |
42 | { | |
43 | _GLIBCXX_BEGIN_NAMESPACE_VERSION | |
3cbc7af0 | 44 | |
e6923541 JW |
45 | __attribute__((__always_inline__)) |
46 | inline bool | |
47 | __is_single_threaded() _GLIBCXX_NOTHROW | |
48 | { | |
49 | #ifndef __GTHREADS | |
50 | return true; | |
51 | #elif __has_include(<sys/single_threaded.h>) | |
52 | return ::__libc_single_threaded; | |
53 | #else | |
54 | return !__gthread_active_p(); | |
55 | #endif | |
56 | } | |
57 | ||
2e362c74 | 58 | // Functions for portable atomic access. |
ee5ca789 | 59 | // To abstract locking primitives across all thread policies, use: |
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60 | // __exchange_and_add_dispatch |
61 | // __atomic_add_dispatch | |
a152e96f | 62 | #ifdef _GLIBCXX_ATOMIC_BUILTINS |
0dc7adb0 JW |
63 | inline _Atomic_word |
64 | __attribute__((__always_inline__)) | |
1b98c24e | 65 | __exchange_and_add(volatile _Atomic_word* __mem, int __val) |
7dcbaaa9 | 66 | { return __atomic_fetch_add(__mem, __val, __ATOMIC_ACQ_REL); } |
1b98c24e | 67 | |
0dc7adb0 JW |
68 | inline void |
69 | __attribute__((__always_inline__)) | |
1b98c24e | 70 | __atomic_add(volatile _Atomic_word* __mem, int __val) |
7dcbaaa9 | 71 | { __atomic_fetch_add(__mem, __val, __ATOMIC_ACQ_REL); } |
1b98c24e | 72 | #else |
b7ee72de | 73 | _Atomic_word |
a10b664e | 74 | __exchange_and_add(volatile _Atomic_word*, int) _GLIBCXX_NOTHROW; |
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75 | |
76 | void | |
a10b664e | 77 | __atomic_add(volatile _Atomic_word*, int) _GLIBCXX_NOTHROW; |
1b98c24e | 78 | #endif |
9268b7cb | 79 | |
0dc7adb0 JW |
80 | inline _Atomic_word |
81 | __attribute__((__always_inline__)) | |
b93d5ca9 | 82 | __exchange_and_add_single(_Atomic_word* __mem, int __val) |
b7ee72de PC |
83 | { |
84 | _Atomic_word __result = *__mem; | |
85 | *__mem += __val; | |
86 | return __result; | |
87 | } | |
88 | ||
0dc7adb0 JW |
89 | inline void |
90 | __attribute__((__always_inline__)) | |
b93d5ca9 | 91 | __atomic_add_single(_Atomic_word* __mem, int __val) |
b7ee72de PC |
92 | { *__mem += __val; } |
93 | ||
0dc7adb0 JW |
94 | inline _Atomic_word |
95 | __attribute__ ((__always_inline__)) | |
b93d5ca9 | 96 | __exchange_and_add_dispatch(_Atomic_word* __mem, int __val) |
b7ee72de | 97 | { |
e6923541 JW |
98 | if (__is_single_threaded()) |
99 | return __exchange_and_add_single(__mem, __val); | |
100 | else | |
701a3eee | 101 | return __exchange_and_add(__mem, __val); |
b7ee72de PC |
102 | } |
103 | ||
0dc7adb0 JW |
104 | inline void |
105 | __attribute__ ((__always_inline__)) | |
b93d5ca9 | 106 | __atomic_add_dispatch(_Atomic_word* __mem, int __val) |
b7ee72de | 107 | { |
e6923541 JW |
108 | if (__is_single_threaded()) |
109 | __atomic_add_single(__mem, __val); | |
110 | else | |
111 | __atomic_add(__mem, __val); | |
b7ee72de PC |
112 | } |
113 | ||
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114 | _GLIBCXX_END_NAMESPACE_VERSION |
115 | } // namespace | |
2c5d0ae8 | 116 | |
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117 | // Even if the CPU doesn't need a memory barrier, we need to ensure |
118 | // that the compiler doesn't reorder memory accesses across the | |
119 | // barriers. | |
445cf5eb | 120 | #ifndef _GLIBCXX_READ_MEM_BARRIER |
57e6d9be | 121 | #define _GLIBCXX_READ_MEM_BARRIER __atomic_thread_fence (__ATOMIC_ACQUIRE) |
445cf5eb JM |
122 | #endif |
123 | #ifndef _GLIBCXX_WRITE_MEM_BARRIER | |
57e6d9be | 124 | #define _GLIBCXX_WRITE_MEM_BARRIER __atomic_thread_fence (__ATOMIC_RELEASE) |
445cf5eb JM |
125 | #endif |
126 | ||
2c5d0ae8 | 127 | #endif |