atomic_support.h revision 300770 
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
41namespace {
42
43#if defined(_LIBCPP_HAS_ATOMIC_BUILTINS) && !defined(_LIBCPP_HAS_NO_THREADS)
44
45enum __libcpp_atomic_order {
46    _AO_Relaxed = __ATOMIC_RELAXED,
47    _AO_Consume = __ATOMIC_CONSUME,
48    _AO_Aquire  = __ATOMIC_ACQUIRE,
49    _AO_Release = __ATOMIC_RELEASE,
50    _AO_Acq_Rel = __ATOMIC_ACQ_REL,
51    _AO_Seq     = __ATOMIC_SEQ_CST
52};
53
54template <class _ValueType, class _FromType>
55inline _LIBCPP_INLINE_VISIBILITY
56void __libcpp_atomic_store(_ValueType* __dest, _FromType __val,
57                           int __order = _AO_Seq)
58{
59    __atomic_store_n(__dest, __val, __order);
60}
61
62template <class _ValueType, class _FromType>
63inline _LIBCPP_INLINE_VISIBILITY
64void __libcpp_relaxed_store(_ValueType* __dest, _FromType __val)
65{
66    __atomic_store_n(__dest, __val, _AO_Relaxed);
67}
68
69template <class _ValueType>
70inline _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
77template <class _ValueType, class _AddType>
78inline _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
85template <class _ValueType>
86inline _LIBCPP_INLINE_VISIBILITY
87bool __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
98enum __libcpp_atomic_order {
99    _AO_Relaxed,
100    _AO_Consume,
101    _AO_Acquire,
102    _AO_Release,
103    _AO_Acq_Rel,
104    _AO_Seq
105};
106
107template <class _ValueType, class _FromType>
108inline _LIBCPP_INLINE_VISIBILITY
109void __libcpp_atomic_store(_ValueType* __dest, _FromType __val,
110                           int = 0)
111{
112    *__dest = __val;
113}
114
115template <class _ValueType, class _FromType>
116inline _LIBCPP_INLINE_VISIBILITY
117void __libcpp_relaxed_store(_ValueType* __dest, _FromType __val)
118{
119    *__dest = __val;
120}
121
122template <class _ValueType>
123inline _LIBCPP_INLINE_VISIBILITY
124_ValueType __libcpp_atomic_load(_ValueType const* __val,
125                                int = 0)
126{
127    return *__val;
128}
129
130template <class _ValueType, class _AddType>
131inline _LIBCPP_INLINE_VISIBILITY
132_ValueType __libcpp_atomic_add(_ValueType* __val, _AddType __a,
133                               int = 0)
134{
135    return *__val += __a;
136}
137
138template <class _ValueType>
139inline _LIBCPP_INLINE_VISIBILITY
140bool __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