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