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) \
16 && __has_builtin(__atomic_store_n) \
17 && __has_builtin(__atomic_add_fetch) \
18 && __has_builtin(__atomic_exchange_n) \
19 && __has_builtin(__atomic_compare_exchange_n) \
20 && defined(__ATOMIC_RELAXED) \
21 && defined(__ATOMIC_CONSUME) \
22 && defined(__ATOMIC_ACQUIRE) \
23 && defined(__ATOMIC_RELEASE) \
24 && defined(__ATOMIC_ACQ_REL) \
25 && defined(__ATOMIC_SEQ_CST)
26 # define _LIBCPP_HAS_ATOMIC_BUILTINS
27 #elif !defined(__clang__) && defined(_GNUC_VER) && _GNUC_VER >= 407
28 # define _LIBCPP_HAS_ATOMIC_BUILTINS
29 #endif
30
31 #if !defined(_LIBCPP_HAS_ATOMIC_BUILTINS) && !defined(_LIBCPP_HAS_NO_THREADS)
32 # if defined(_LIBCPP_WARNING)
33 _LIBCPP_WARNING("Building libc++ without __atomic builtins is unsupported")
34 # else
35 # warning Building libc++ without __atomic builtins is unsupported
36 # endif
37 #endif
38
39 _LIBCPP_BEGIN_NAMESPACE_STD
40
41 namespace {
42
43 #if defined(_LIBCPP_HAS_ATOMIC_BUILTINS) && !defined(_LIBCPP_HAS_NO_THREADS)
44
45 enum __libcpp_atomic_order {
46 _AO_Relaxed = __ATOMIC_RELAXED,
47 _AO_Consume = __ATOMIC_CONSUME,
48 _AO_Acquire = __ATOMIC_ACQUIRE,
49 _AO_Release = __ATOMIC_RELEASE,
50 _AO_Acq_Rel = __ATOMIC_ACQ_REL,
51 _AO_Seq = __ATOMIC_SEQ_CST
52 };
53
54 template <class _ValueType, class _FromType>
55 inline _LIBCPP_INLINE_VISIBILITY
56 void __libcpp_atomic_store(_ValueType* __dest, _FromType __val,
57 int __order = _AO_Seq)
58 {
59 __atomic_store_n(__dest, __val, __order);
60 }
61
62 template <class _ValueType, class _FromType>
63 inline _LIBCPP_INLINE_VISIBILITY
__libcpp_relaxed_store(_ValueType * __dest,_FromType __val)64 void __libcpp_relaxed_store(_ValueType* __dest, _FromType __val)
65 {
66 __atomic_store_n(__dest, __val, _AO_Relaxed);
67 }
68
69 template <class _ValueType>
70 inline _LIBCPP_INLINE_VISIBILITY
71 _ValueType __libcpp_atomic_load(_ValueType const* __val,
72 int __order = _AO_Seq)
73 {
74 return __atomic_load_n(__val, __order);
75 }
76
77 template <class _ValueType, class _AddType>
78 inline _LIBCPP_INLINE_VISIBILITY
79 _ValueType __libcpp_atomic_add(_ValueType* __val, _AddType __a,
80 int __order = _AO_Seq)
81 {
82 return __atomic_add_fetch(__val, __a, __order);
83 }
84
85 template <class _ValueType>
86 inline _LIBCPP_INLINE_VISIBILITY
87 _ValueType __libcpp_atomic_exchange(_ValueType* __target,
88 _ValueType __value, int __order = _AO_Seq)
89 {
90 return __atomic_exchange_n(__target, __value, __order);
91 }
92
93 template <class _ValueType>
94 inline _LIBCPP_INLINE_VISIBILITY
95 bool __libcpp_atomic_compare_exchange(_ValueType* __val,
96 _ValueType* __expected, _ValueType __after,
97 int __success_order = _AO_Seq,
98 int __fail_order = _AO_Seq)
99 {
100 return __atomic_compare_exchange_n(__val, __expected, __after, true,
101 __success_order, __fail_order);
102 }
103
104 #else // _LIBCPP_HAS_NO_THREADS
105
106 enum __libcpp_atomic_order {
107 _AO_Relaxed,
108 _AO_Consume,
109 _AO_Acquire,
110 _AO_Release,
111 _AO_Acq_Rel,
112 _AO_Seq
113 };
114
115 template <class _ValueType, class _FromType>
116 inline _LIBCPP_INLINE_VISIBILITY
117 void __libcpp_atomic_store(_ValueType* __dest, _FromType __val,
118 int = 0)
119 {
120 *__dest = __val;
121 }
122
123 template <class _ValueType, class _FromType>
124 inline _LIBCPP_INLINE_VISIBILITY
125 void __libcpp_relaxed_store(_ValueType* __dest, _FromType __val)
126 {
127 *__dest = __val;
128 }
129
130 template <class _ValueType>
131 inline _LIBCPP_INLINE_VISIBILITY
132 _ValueType __libcpp_atomic_load(_ValueType const* __val,
133 int = 0)
134 {
135 return *__val;
136 }
137
138 template <class _ValueType, class _AddType>
139 inline _LIBCPP_INLINE_VISIBILITY
140 _ValueType __libcpp_atomic_add(_ValueType* __val, _AddType __a,
141 int = 0)
142 {
143 return *__val += __a;
144 }
145
146 template <class _ValueType>
147 inline _LIBCPP_INLINE_VISIBILITY
148 _ValueType __libcpp_atomic_exchange(_ValueType* __target,
149 _ValueType __value, int __order = _AO_Seq)
150 {
151 _ValueType old = *__target;
152 *__target = __value;
153 return old;
154 }
155
156 template <class _ValueType>
157 inline _LIBCPP_INLINE_VISIBILITY
158 bool __libcpp_atomic_compare_exchange(_ValueType* __val,
159 _ValueType* __expected, _ValueType __after,
160 int = 0, int = 0)
161 {
162 if (*__val == *__expected) {
163 *__val = __after;
164 return true;
165 }
166 *__expected = *__val;
167 return false;
168 }
169
170 #endif // _LIBCPP_HAS_NO_THREADS
171
172 } // end namespace
173
174 _LIBCPP_END_NAMESPACE_STD
175
176 #endif // ATOMIC_SUPPORT_H
177