1 //===----------------------------------------------------------------------===////
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is dual licensed under the MIT and the University of Illinois Open
6 // Source Licenses. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===////
9 
10 #ifndef ATOMIC_SUPPORT_H
11 #define ATOMIC_SUPPORT_H
12 
13 #include "__config"
14 #include "memory" // for __libcpp_relaxed_load
15 
16 #if defined(__clang__) && __has_builtin(__atomic_load_n)             \
17                        && __has_builtin(__atomic_store_n)            \
18                        && __has_builtin(__atomic_add_fetch)          \
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(_MSC_VER) && !defined(__clang__)
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
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 bool __libcpp_atomic_compare_exchange(_ValueType* __val,
88     _ValueType* __expected, _ValueType __after,
89     int __success_order = _AO_Seq,
90     int __fail_order = _AO_Seq)
91 {
92     return __atomic_compare_exchange_n(__val, __expected, __after, true,
93                                        __success_order, __fail_order);
94 }
95 
96 #else // _LIBCPP_HAS_NO_THREADS
97 
98 enum __libcpp_atomic_order {
99     _AO_Relaxed,
100     _AO_Consume,
101     _AO_Acquire,
102     _AO_Release,
103     _AO_Acq_Rel,
104     _AO_Seq
105 };
106 
107 template <class _ValueType, class _FromType>
108 inline _LIBCPP_INLINE_VISIBILITY
109 void __libcpp_atomic_store(_ValueType* __dest, _FromType __val,
110                            int = 0)
111 {
112     *__dest = __val;
113 }
114 
115 template <class _ValueType, class _FromType>
116 inline _LIBCPP_INLINE_VISIBILITY
117 void __libcpp_relaxed_store(_ValueType* __dest, _FromType __val)
118 {
119     *__dest = __val;
120 }
121 
122 template <class _ValueType>
123 inline _LIBCPP_INLINE_VISIBILITY
124 _ValueType __libcpp_atomic_load(_ValueType const* __val,
125                                 int = 0)
126 {
127     return *__val;
128 }
129 
130 template <class _ValueType, class _AddType>
131 inline _LIBCPP_INLINE_VISIBILITY
132 _ValueType __libcpp_atomic_add(_ValueType* __val, _AddType __a,
133                                int = 0)
134 {
135     return *__val += __a;
136 }
137 
138 template <class _ValueType>
139 inline _LIBCPP_INLINE_VISIBILITY
140 bool __libcpp_atomic_compare_exchange(_ValueType* __val,
141     _ValueType* __expected, _ValueType __after,
142     int = 0, int = 0)
143 {
144     if (*__val == *__expected) {
145         *__val = __after;
146         return true;
147     }
148     *__expected = *__val;
149     return false;
150 }
151 
152 #endif // _LIBCPP_HAS_NO_THREADS
153 
154 } // end namespace
155 
156 _LIBCPP_END_NAMESPACE_STD
157 
158 #endif // ATOMIC_SUPPORT_H
159