1//===----------------------------------------------------------------------===////
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===////
8
9#ifndef ATOMIC_SUPPORT_H
10#define ATOMIC_SUPPORT_H
11
12#include <__config>
13#include <memory> // for __libcpp_relaxed_load
14
15#if defined(__clang__) && __has_builtin(__atomic_load_n) && __has_builtin(__atomic_store_n) && \
16 __has_builtin(__atomic_add_fetch) && __has_builtin(__atomic_exchange_n) && \
17 __has_builtin(__atomic_compare_exchange_n) && defined(__ATOMIC_RELAXED) && defined(__ATOMIC_CONSUME) && \
18 defined(__ATOMIC_ACQUIRE) && defined(__ATOMIC_RELEASE) && defined(__ATOMIC_ACQ_REL) && defined(__ATOMIC_SEQ_CST)
19# define _LIBCPP_HAS_ATOMIC_BUILTINS
20#elif defined(_LIBCPP_COMPILER_GCC)
21# define _LIBCPP_HAS_ATOMIC_BUILTINS
22#endif
23
24#if !defined(_LIBCPP_HAS_ATOMIC_BUILTINS) && _LIBCPP_HAS_THREADS
25# if defined(_LIBCPP_WARNING)
26_LIBCPP_WARNING("Building libc++ without __atomic builtins is unsupported")
27# else
28# warning Building libc++ without __atomic builtins is unsupported
29# endif
30#endif
31
32_LIBCPP_BEGIN_NAMESPACE_STD
33
34namespace {
35
36#if defined(_LIBCPP_HAS_ATOMIC_BUILTINS) && _LIBCPP_HAS_THREADS
37
38enum __libcpp_atomic_order {
39 _AO_Relaxed = __ATOMIC_RELAXED,
40 _AO_Consume = __ATOMIC_CONSUME,
41 _AO_Acquire = __ATOMIC_ACQUIRE,
42 _AO_Release = __ATOMIC_RELEASE,
43 _AO_Acq_Rel = __ATOMIC_ACQ_REL,
44 _AO_Seq = __ATOMIC_SEQ_CST
45};
46
47template <class _ValueType, class _FromType>
48inline _LIBCPP_HIDE_FROM_ABI void __libcpp_atomic_store(_ValueType* __dest, _FromType __val, int __order = _AO_Seq) {
49 __atomic_store_n(__dest, __val, __order);
50}
51
52template <class _ValueType, class _FromType>
53inline _LIBCPP_HIDE_FROM_ABI void __libcpp_relaxed_store(_ValueType* __dest, _FromType __val) {
54 __atomic_store_n(__dest, __val, _AO_Relaxed);
55}
56
57template <class _ValueType>
58inline _LIBCPP_HIDE_FROM_ABI _ValueType __libcpp_atomic_load(_ValueType const* __val, int __order = _AO_Seq) {
59 return __atomic_load_n(__val, __order);
60}
61
62template <class _ValueType, class _AddType>
63inline _LIBCPP_HIDE_FROM_ABI _ValueType __libcpp_atomic_add(_ValueType* __val, _AddType __a, int __order = _AO_Seq) {
64 return __atomic_add_fetch(__val, __a, __order);
65}
66
67template <class _ValueType>
68inline _LIBCPP_HIDE_FROM_ABI _ValueType
69__libcpp_atomic_exchange(_ValueType* __target, _ValueType __value, int __order = _AO_Seq) {
70 return __atomic_exchange_n(__target, __value, __order);
71}
72
73template <class _ValueType>
74inline _LIBCPP_HIDE_FROM_ABI bool __libcpp_atomic_compare_exchange(
75 _ValueType* __val,
76 _ValueType* __expected,
77 _ValueType __after,
78 int __success_order = _AO_Seq,
79 int __fail_order = _AO_Seq) {
80 return __atomic_compare_exchange_n(__val, __expected, __after, true, __success_order, __fail_order);
81}
82
83#else // _LIBCPP_HAS_THREADS
84
85enum __libcpp_atomic_order { _AO_Relaxed, _AO_Consume, _AO_Acquire, _AO_Release, _AO_Acq_Rel, _AO_Seq };
86
87template <class _ValueType, class _FromType>
88inline _LIBCPP_HIDE_FROM_ABI void __libcpp_atomic_store(_ValueType* __dest, _FromType __val, int = 0) {
89 *__dest = __val;
90}
91
92template <class _ValueType, class _FromType>
93inline _LIBCPP_HIDE_FROM_ABI void __libcpp_relaxed_store(_ValueType* __dest, _FromType __val) {
94 *__dest = __val;
95}
96
97template <class _ValueType>
98inline _LIBCPP_HIDE_FROM_ABI _ValueType __libcpp_atomic_load(_ValueType const* __val, int = 0) {
99 return *__val;
100}
101
102template <class _ValueType, class _AddType>
103inline _LIBCPP_HIDE_FROM_ABI _ValueType __libcpp_atomic_add(_ValueType* __val, _AddType __a, int = 0) {
104 return *__val += __a;
105}
106
107template <class _ValueType>
108inline _LIBCPP_HIDE_FROM_ABI _ValueType
109__libcpp_atomic_exchange(_ValueType* __target, _ValueType __value, int = _AO_Seq) {
110 _ValueType old = *__target;
111 *__target = __value;
112 return old;
113}
114
115template <class _ValueType>
116inline _LIBCPP_HIDE_FROM_ABI bool
117__libcpp_atomic_compare_exchange(_ValueType* __val, _ValueType* __expected, _ValueType __after, int = 0, int = 0) {
118 if (*__val == *__expected) {
119 *__val = __after;
120 return true;
121 }
122 *__expected = *__val;
123 return false;
124}
125
126#endif // _LIBCPP_HAS_THREADS
127
128} // namespace
129
130_LIBCPP_END_NAMESPACE_STD
131
132#endif // ATOMIC_SUPPORT_H
133