llvm-project/libcxx/include/__atomic/atomic.h

//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#ifndef _LIBCPP___ATOMIC_ATOMIC_H
#define _LIBCPP___ATOMIC_ATOMIC_H

#include <__atomic/atomic_sync.h>
#include <__atomic/check_memory_order.h>
#include <__atomic/floating_point_helper.h>
#include <__atomic/is_always_lock_free.h>
#include <__atomic/memory_order.h>
#include <__atomic/support.h>
#include <__config>
#include <__cstddef/ptrdiff_t.h>
#include <__memory/addressof.h>
#include <__type_traits/enable_if.h>
#include <__type_traits/is_floating_point.h>
#include <__type_traits/is_function.h>
#include <__type_traits/is_integral.h>
#include <__type_traits/is_nothrow_constructible.h>
#include <__type_traits/is_same.h>
#include <__type_traits/is_trivially_copyable.h>
#include <__type_traits/remove_const.h>
#include <__type_traits/remove_pointer.h>
#include <__type_traits/remove_volatile.h>
#include <__utility/forward.h>
#include <cstring>

#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
#  pragma GCC system_header
#endif

_LIBCPP_BEGIN_NAMESPACE_STD

template <class _Tp, bool = is_integral<_Tp>::value && !is_same<_Tp, bool>::value>
struct __atomic_base // false
{
  mutable __cxx_atomic_impl<_Tp> __a_;

  using value_type = _Tp;

#if _LIBCPP_STD_VER >= 17
  static constexpr bool is_always_lock_free = __libcpp_is_always_lock_free<__cxx_atomic_impl<_Tp> >::__value;
#endif

  _LIBCPP_HIDE_FROM_ABI bool is_lock_free() const volatile _NOEXCEPT {
    return __cxx_atomic_is_lock_free(sizeof(__cxx_atomic_impl<_Tp>));
  }
  _LIBCPP_HIDE_FROM_ABI bool is_lock_free() const _NOEXCEPT {
    return static_cast<__atomic_base const volatile*>(this)->is_lock_free();
  }
  _LIBCPP_HIDE_FROM_ABI void store(_Tp __d, memory_order __m = memory_order_seq_cst) volatile _NOEXCEPT
      _LIBCPP_CHECK_STORE_MEMORY_ORDER(__m) {
    std::__cxx_atomic_store(std::addressof(__a_), __d, __m);
  }
  _LIBCPP_HIDE_FROM_ABI void store(_Tp __d, memory_order __m = memory_order_seq_cst) _NOEXCEPT
      _LIBCPP_CHECK_STORE_MEMORY_ORDER(__m) {
    std::__cxx_atomic_store(std::addressof(__a_), __d, __m);
  }
  _LIBCPP_HIDE_FROM_ABI _Tp load(memory_order __m = memory_order_seq_cst) const volatile _NOEXCEPT
      _LIBCPP_CHECK_LOAD_MEMORY_ORDER(__m) {
    return std::__cxx_atomic_load(std::addressof(__a_), __m);
  }
  _LIBCPP_HIDE_FROM_ABI _Tp load(memory_order __m = memory_order_seq_cst) const _NOEXCEPT
      _LIBCPP_CHECK_LOAD_MEMORY_ORDER(__m) {
    return std::__cxx_atomic_load(std::addressof(__a_), __m);
  }
  _LIBCPP_HIDE_FROM_ABI operator _Tp() const volatile _NOEXCEPT { return load(); }
  _LIBCPP_HIDE_FROM_ABI operator _Tp() const _NOEXCEPT { return load(); }
  _LIBCPP_HIDE_FROM_ABI _Tp exchange(_Tp __d, memory_order __m = memory_order_seq_cst) volatile _NOEXCEPT {
    return std::__cxx_atomic_exchange(std::addressof(__a_), __d, __m);
  }
  _LIBCPP_HIDE_FROM_ABI _Tp exchange(_Tp __d, memory_order __m = memory_order_seq_cst) _NOEXCEPT {
    return std::__cxx_atomic_exchange(std::addressof(__a_), __d, __m);
  }
  _LIBCPP_HIDE_FROM_ABI bool
  compare_exchange_weak(_Tp& __e, _Tp __d, memory_order __s, memory_order __f) volatile _NOEXCEPT
      _LIBCPP_CHECK_EXCHANGE_MEMORY_ORDER(__s, __f) {
    return std::__cxx_atomic_compare_exchange_weak(std::addressof(__a_), std::addressof(__e), __d, __s, __f);
  }
  _LIBCPP_HIDE_FROM_ABI bool compare_exchange_weak(_Tp& __e, _Tp __d, memory_order __s, memory_order __f) _NOEXCEPT
      _LIBCPP_CHECK_EXCHANGE_MEMORY_ORDER(__s, __f) {
    return std::__cxx_atomic_compare_exchange_weak(std::addressof(__a_), std::addressof(__e), __d, __s, __f);
  }
  _LIBCPP_HIDE_FROM_ABI bool
  compare_exchange_strong(_Tp& __e, _Tp __d, memory_order __s, memory_order __f) volatile _NOEXCEPT
      _LIBCPP_CHECK_EXCHANGE_MEMORY_ORDER(__s, __f) {
    return std::__cxx_atomic_compare_exchange_strong(std::addressof(__a_), std::addressof(__e), __d, __s, __f);
  }
  _LIBCPP_HIDE_FROM_ABI bool compare_exchange_strong(_Tp& __e, _Tp __d, memory_order __s, memory_order __f) _NOEXCEPT
      _LIBCPP_CHECK_EXCHANGE_MEMORY_ORDER(__s, __f) {
    return std::__cxx_atomic_compare_exchange_strong(std::addressof(__a_), std::addressof(__e), __d, __s, __f);
  }
  _LIBCPP_HIDE_FROM_ABI bool
  compare_exchange_weak(_Tp& __e, _Tp __d, memory_order __m = memory_order_seq_cst) volatile _NOEXCEPT {
    return std::__cxx_atomic_compare_exchange_weak(std::addressof(__a_), std::addressof(__e), __d, __m, __m);
  }
  _LIBCPP_HIDE_FROM_ABI bool
  compare_exchange_weak(_Tp& __e, _Tp __d, memory_order __m = memory_order_seq_cst) _NOEXCEPT {
    return std::__cxx_atomic_compare_exchange_weak(std::addressof(__a_), std::addressof(__e), __d, __m, __m);
  }
  _LIBCPP_HIDE_FROM_ABI bool
  compare_exchange_strong(_Tp& __e, _Tp __d, memory_order __m = memory_order_seq_cst) volatile _NOEXCEPT {
    return std::__cxx_atomic_compare_exchange_strong(std::addressof(__a_), std::addressof(__e), __d, __m, __m);
  }
  _LIBCPP_HIDE_FROM_ABI bool
  compare_exchange_strong(_Tp& __e, _Tp __d, memory_order __m = memory_order_seq_cst) _NOEXCEPT {
    return std::__cxx_atomic_compare_exchange_strong(std::addressof(__a_), std::addressof(__e), __d, __m, __m);
  }

#if _LIBCPP_STD_VER >= 20
  _LIBCPP_HIDE_FROM_ABI void wait(_Tp __v, memory_order __m = memory_order_seq_cst) const volatile _NOEXCEPT {
    std::__atomic_wait(*this, __v, __m);
  }
  _LIBCPP_HIDE_FROM_ABI void wait(_Tp __v, memory_order __m = memory_order_seq_cst) const _NOEXCEPT {
    std::__atomic_wait(*this, __v, __m);
  }
  _LIBCPP_HIDE_FROM_ABI void notify_one() volatile _NOEXCEPT { std::__atomic_notify_one(*this); }
  _LIBCPP_HIDE_FROM_ABI void notify_one() _NOEXCEPT { std::__atomic_notify_one(*this); }
  _LIBCPP_HIDE_FROM_ABI void notify_all() volatile _NOEXCEPT { std::__atomic_notify_all(*this); }
  _LIBCPP_HIDE_FROM_ABI void notify_all() _NOEXCEPT { std::__atomic_notify_all(*this); }
#endif //  _LIBCPP_STD_VER >= 20

#if _LIBCPP_STD_VER >= 20
  _LIBCPP_HIDE_FROM_ABI constexpr __atomic_base() noexcept(is_nothrow_default_constructible_v<_Tp>) : __a_(_Tp()) {}
#else
  _LIBCPP_HIDE_FROM_ABI __atomic_base() _NOEXCEPT = default;
#endif

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR __atomic_base(_Tp __d) _NOEXCEPT : __a_(__d) {}

  __atomic_base(const __atomic_base&) = delete;
};

// atomic<Integral>

template <class _Tp>
struct __atomic_base<_Tp, true> : public __atomic_base<_Tp, false> {
  using __base _LIBCPP_NODEBUG = __atomic_base<_Tp, false>;

  using difference_type = typename __base::value_type;

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 __atomic_base() _NOEXCEPT = default;

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR __atomic_base(_Tp __d) _NOEXCEPT : __base(__d) {}

  _LIBCPP_HIDE_FROM_ABI _Tp fetch_add(_Tp __op, memory_order __m = memory_order_seq_cst) volatile _NOEXCEPT {
    return std::__cxx_atomic_fetch_add(std::addressof(this->__a_), __op, __m);
  }
  _LIBCPP_HIDE_FROM_ABI _Tp fetch_add(_Tp __op, memory_order __m = memory_order_seq_cst) _NOEXCEPT {
    return std::__cxx_atomic_fetch_add(std::addressof(this->__a_), __op, __m);
  }
  _LIBCPP_HIDE_FROM_ABI _Tp fetch_sub(_Tp __op, memory_order __m = memory_order_seq_cst) volatile _NOEXCEPT {
    return std::__cxx_atomic_fetch_sub(std::addressof(this->__a_), __op, __m);
  }
  _LIBCPP_HIDE_FROM_ABI _Tp fetch_sub(_Tp __op, memory_order __m = memory_order_seq_cst) _NOEXCEPT {
    return std::__cxx_atomic_fetch_sub(std::addressof(this->__a_), __op, __m);
  }
  _LIBCPP_HIDE_FROM_ABI _Tp fetch_and(_Tp __op, memory_order __m = memory_order_seq_cst) volatile _NOEXCEPT {
    return std::__cxx_atomic_fetch_and(std::addressof(this->__a_), __op, __m);
  }
  _LIBCPP_HIDE_FROM_ABI _Tp fetch_and(_Tp __op, memory_order __m = memory_order_seq_cst) _NOEXCEPT {
    return std::__cxx_atomic_fetch_and(std::addressof(this->__a_), __op, __m);
  }
  _LIBCPP_HIDE_FROM_ABI _Tp fetch_or(_Tp __op, memory_order __m = memory_order_seq_cst) volatile _NOEXCEPT {
    return std::__cxx_atomic_fetch_or(std::addressof(this->__a_), __op, __m);
  }
  _LIBCPP_HIDE_FROM_ABI _Tp fetch_or(_Tp __op, memory_order __m = memory_order_seq_cst) _NOEXCEPT {
    return std::__cxx_atomic_fetch_or(std::addressof(this->__a_), __op, __m);
  }
  _LIBCPP_HIDE_FROM_ABI _Tp fetch_xor(_Tp __op, memory_order __m = memory_order_seq_cst) volatile _NOEXCEPT {
    return std::__cxx_atomic_fetch_xor(std::addressof(this->__a_), __op, __m);
  }
  _LIBCPP_HIDE_FROM_ABI _Tp fetch_xor(_Tp __op, memory_order __m = memory_order_seq_cst) _NOEXCEPT {
    return std::__cxx_atomic_fetch_xor(std::addressof(this->__a_), __op, __m);
  }

  _LIBCPP_HIDE_FROM_ABI _Tp operator++(int) volatile _NOEXCEPT { return fetch_add(_Tp(1)); }
  _LIBCPP_HIDE_FROM_ABI _Tp operator++(int) _NOEXCEPT { return fetch_add(_Tp(1)); }
  _LIBCPP_HIDE_FROM_ABI _Tp operator--(int) volatile _NOEXCEPT { return fetch_sub(_Tp(1)); }
  _LIBCPP_HIDE_FROM_ABI _Tp operator--(int) _NOEXCEPT { return fetch_sub(_Tp(1)); }
  _LIBCPP_HIDE_FROM_ABI _Tp operator++() volatile _NOEXCEPT { return fetch_add(_Tp(1)) + _Tp(1); }
  _LIBCPP_HIDE_FROM_ABI _Tp operator++() _NOEXCEPT { return fetch_add(_Tp(1)) + _Tp(1); }
  _LIBCPP_HIDE_FROM_ABI _Tp operator--() volatile _NOEXCEPT { return fetch_sub(_Tp(1)) - _Tp(1); }
  _LIBCPP_HIDE_FROM_ABI _Tp operator--() _NOEXCEPT { return fetch_sub(_Tp(1)) - _Tp(1); }
  _LIBCPP_HIDE_FROM_ABI _Tp operator+=(_Tp __op) volatile _NOEXCEPT { return fetch_add(__op) + __op; }
  _LIBCPP_HIDE_FROM_ABI _Tp operator+=(_Tp __op) _NOEXCEPT { return fetch_add(__op) + __op; }
  _LIBCPP_HIDE_FROM_ABI _Tp operator-=(_Tp __op) volatile _NOEXCEPT { return fetch_sub(__op) - __op; }
  _LIBCPP_HIDE_FROM_ABI _Tp operator-=(_Tp __op) _NOEXCEPT { return fetch_sub(__op) - __op; }
  _LIBCPP_HIDE_FROM_ABI _Tp operator&=(_Tp __op) volatile _NOEXCEPT { return fetch_and(__op) & __op; }
  _LIBCPP_HIDE_FROM_ABI _Tp operator&=(_Tp __op) _NOEXCEPT { return fetch_and(__op) & __op; }
  _LIBCPP_HIDE_FROM_ABI _Tp operator|=(_Tp __op) volatile _NOEXCEPT { return fetch_or(__op) | __op; }
  _LIBCPP_HIDE_FROM_ABI _Tp operator|=(_Tp __op) _NOEXCEPT { return fetch_or(__op) | __op; }
  _LIBCPP_HIDE_FROM_ABI _Tp operator^=(_Tp __op) volatile _NOEXCEPT { return fetch_xor(__op) ^ __op; }
  _LIBCPP_HIDE_FROM_ABI _Tp operator^=(_Tp __op) _NOEXCEPT { return fetch_xor(__op) ^ __op; }
};

// Here we need _IsIntegral because the default template argument is not enough
// e.g  __atomic_base<int> is __atomic_base<int, true>, which inherits from
// __atomic_base<int, false> and the caller of the wait function is
// __atomic_base<int, false>. So specializing __atomic_base<_Tp> does not work
template <class _Tp, bool _IsIntegral>
struct __atomic_waitable_traits<__atomic_base<_Tp, _IsIntegral> > {
  using __value_type _LIBCPP_NODEBUG = _Tp;

  static _LIBCPP_HIDE_FROM_ABI _Tp __atomic_load(const __atomic_base<_Tp, _IsIntegral>& __a, memory_order __order) {
    return __a.load(__order);
  }

  static _LIBCPP_HIDE_FROM_ABI _Tp
  __atomic_load(const volatile __atomic_base<_Tp, _IsIntegral>& __this, memory_order __order) {
    return __this.load(__order);
  }

  static _LIBCPP_HIDE_FROM_ABI const __cxx_atomic_impl<_Tp>*
  __atomic_contention_address(const __atomic_base<_Tp, _IsIntegral>& __a) {
    return std::addressof(__a.__a_);
  }

  static _LIBCPP_HIDE_FROM_ABI const volatile __cxx_atomic_impl<_Tp>*
  __atomic_contention_address(const volatile __atomic_base<_Tp, _IsIntegral>& __this) {
    return std::addressof(__this.__a_);
  }
};

template <typename _Tp>
struct __check_atomic_mandates {
  using type _LIBCPP_NODEBUG = _Tp;
  static_assert(is_trivially_copyable<_Tp>::value, "std::atomic<T> requires that 'T' be a trivially copyable type");
};

template <class _Tp>
struct atomic : public __atomic_base<typename __check_atomic_mandates<_Tp>::type> {
  using __base _LIBCPP_NODEBUG = __atomic_base<_Tp>;

#if _LIBCPP_STD_VER >= 20
  _LIBCPP_HIDE_FROM_ABI atomic() = default;
#else
  _LIBCPP_HIDE_FROM_ABI atomic() _NOEXCEPT = default;
#endif

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR atomic(_Tp __d) _NOEXCEPT : __base(__d) {}

  _LIBCPP_HIDE_FROM_ABI _Tp operator=(_Tp __d) volatile _NOEXCEPT {
    __base::store(__d);
    return __d;
  }
  _LIBCPP_HIDE_FROM_ABI _Tp operator=(_Tp __d) _NOEXCEPT {
    __base::store(__d);
    return __d;
  }

  atomic& operator=(const atomic&)          = delete;
  atomic& operator=(const atomic&) volatile = delete;
};

// atomic<T*>

template <class _Tp>
struct atomic<_Tp*> : public __atomic_base<_Tp*> {
  using __base _LIBCPP_NODEBUG = __atomic_base<_Tp*>;

  using difference_type = ptrdiff_t;

  _LIBCPP_HIDE_FROM_ABI atomic() _NOEXCEPT = default;

  _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR atomic(_Tp* __d) _NOEXCEPT : __base(__d) {}

  _LIBCPP_HIDE_FROM_ABI _Tp* operator=(_Tp* __d) volatile _NOEXCEPT {
    __base::store(__d);
    return __d;
  }
  _LIBCPP_HIDE_FROM_ABI _Tp* operator=(_Tp* __d) _NOEXCEPT {
    __base::store(__d);
    return __d;
  }

  _LIBCPP_HIDE_FROM_ABI _Tp* fetch_add(ptrdiff_t __op, memory_order __m = memory_order_seq_cst) volatile _NOEXCEPT {
    // __atomic_fetch_add accepts function pointers, guard against them.
    static_assert(!is_function<__remove_pointer_t<_Tp> >::value, "Pointer to function isn't allowed");
    return std::__cxx_atomic_fetch_add(std::addressof(this->__a_), __op, __m);
  }

  _LIBCPP_HIDE_FROM_ABI _Tp* fetch_add(ptrdiff_t __op, memory_order __m = memory_order_seq_cst) _NOEXCEPT {
    // __atomic_fetch_add accepts function pointers, guard against them.
    static_assert(!is_function<__remove_pointer_t<_Tp> >::value, "Pointer to function isn't allowed");
    return std::__cxx_atomic_fetch_add(std::addressof(this->__a_), __op, __m);
  }

  _LIBCPP_HIDE_FROM_ABI _Tp* fetch_sub(ptrdiff_t __op, memory_order __m = memory_order_seq_cst) volatile _NOEXCEPT {
    // __atomic_fetch_add accepts function pointers, guard against them.
    static_assert(!is_function<__remove_pointer_t<_Tp> >::value, "Pointer to function isn't allowed");
    return std::__cxx_atomic_fetch_sub(std::addressof(this->__a_), __op, __m);
  }

  _LIBCPP_HIDE_FROM_ABI _Tp* fetch_sub(ptrdiff_t __op, memory_order __m = memory_order_seq_cst) _NOEXCEPT {
    // __atomic_fetch_add accepts function pointers, guard against them.
    static_assert(!is_function<__remove_pointer_t<_Tp> >::value, "Pointer to function isn't allowed");
    return std::__cxx_atomic_fetch_sub(std::addressof(this->__a_), __op, __m);
  }

  _LIBCPP_HIDE_FROM_ABI _Tp* operator++(int) volatile _NOEXCEPT { return fetch_add(1); }
  _LIBCPP_HIDE_FROM_ABI _Tp* operator++(int) _NOEXCEPT { return fetch_add(1); }
  _LIBCPP_HIDE_FROM_ABI _Tp* operator--(int) volatile _NOEXCEPT { return fetch_sub(1); }
  _LIBCPP_HIDE_FROM_ABI _Tp* operator--(int) _NOEXCEPT { return fetch_sub(1); }
  _LIBCPP_HIDE_FROM_ABI _Tp* operator++() volatile _NOEXCEPT { return fetch_add(1) + 1; }
  _LIBCPP_HIDE_FROM_ABI _Tp* operator++() _NOEXCEPT { return fetch_add(1) + 1; }
  _LIBCPP_HIDE_FROM_ABI _Tp* operator--() volatile _NOEXCEPT { return fetch_sub(1) - 1; }
  _LIBCPP_HIDE_FROM_ABI _Tp* operator--() _NOEXCEPT { return fetch_sub(1) - 1; }
  _LIBCPP_HIDE_FROM_ABI _Tp* operator+=(ptrdiff_t __op) volatile _NOEXCEPT { return fetch_add(__op) + __op; }
  _LIBCPP_HIDE_FROM_ABI _Tp* operator+=(ptrdiff_t __op) _NOEXCEPT { return fetch_add(__op) + __op; }
  _LIBCPP_HIDE_FROM_ABI _Tp* operator-=(ptrdiff_t __op) volatile _NOEXCEPT { return fetch_sub(__op) - __op; }
  _LIBCPP_HIDE_FROM_ABI _Tp* operator-=(ptrdiff_t __op) _NOEXCEPT { return fetch_sub(__op) - __op; }

  atomic& operator=(const atomic&)          = delete;
  atomic& operator=(const atomic&) volatile = delete;
};

template <class _Tp>
struct __atomic_waitable_traits<atomic<_Tp> > : __atomic_waitable_traits<__atomic_base<_Tp> > {};

#if _LIBCPP_STD_VER >= 20
template <class _Tp>
  requires is_floating_point_v<_Tp>
struct atomic<_Tp> : __atomic_base<_Tp> {
private:
  template <class _This, class _Operation, class _BuiltinOp>
  _LIBCPP_HIDE_FROM_ABI static _Tp
  __rmw_op(_This&& __self, _Tp __operand, memory_order __m, _Operation __operation, _BuiltinOp __builtin_op) {
    if constexpr (std::__has_rmw_builtin<_Tp>()) {
      return __builtin_op(std::addressof(std::forward<_This>(__self).__a_), __operand, __m);
    } else {
      _Tp __old = __self.load(memory_order_relaxed);
      _Tp __new = __operation(__old, __operand);
      while (!__self.compare_exchange_weak(__old, __new, __m, memory_order_relaxed)) {
#  ifdef _LIBCPP_COMPILER_CLANG_BASED
        if constexpr (std::__is_fp80_long_double<_Tp>()) {
          // https://llvm.org/PR47978
          // clang bug: __old is not updated on failure for atomic<long double>::compare_exchange_weak
          // Note __old = __self.load(memory_order_relaxed) will not work
          std::__cxx_atomic_load_inplace(std::addressof(__self.__a_), std::addressof(__old), memory_order_relaxed);
        }
#  endif
        __new = __operation(__old, __operand);
      }
      return __old;
    }
  }

  template <class _This>
  _LIBCPP_HIDE_FROM_ABI static _Tp __fetch_add(_This&& __self, _Tp __operand, memory_order __m) {
    auto __builtin_op = [](auto __a, auto __builtin_operand, auto __order) {
      return std::__cxx_atomic_fetch_add(__a, __builtin_operand, __order);
    };
    auto __plus = [](auto __a, auto __b) { return __a + __b; };
    return __rmw_op(std::forward<_This>(__self), __operand, __m, __plus, __builtin_op);
  }

  template <class _This>
  _LIBCPP_HIDE_FROM_ABI static _Tp __fetch_sub(_This&& __self, _Tp __operand, memory_order __m) {
    auto __builtin_op = [](auto __a, auto __builtin_operand, auto __order) {
      return std::__cxx_atomic_fetch_sub(__a, __builtin_operand, __order);
    };
    auto __minus = [](auto __a, auto __b) { return __a - __b; };
    return __rmw_op(std::forward<_This>(__self), __operand, __m, __minus, __builtin_op);
  }

public:
  using __base _LIBCPP_NODEBUG = __atomic_base<_Tp>;
  using value_type             = _Tp;
  using difference_type        = value_type;

  _LIBCPP_HIDE_FROM_ABI constexpr atomic() noexcept = default;
  _LIBCPP_HIDE_FROM_ABI constexpr atomic(_Tp __d) noexcept : __base(__d) {}

  atomic(const atomic&)                     = delete;
  atomic& operator=(const atomic&)          = delete;
  atomic& operator=(const atomic&) volatile = delete;

  _LIBCPP_HIDE_FROM_ABI _Tp operator=(_Tp __d) volatile noexcept
    requires __base::is_always_lock_free
  {
    __base::store(__d);
    return __d;
  }
  _LIBCPP_HIDE_FROM_ABI _Tp operator=(_Tp __d) noexcept {
    __base::store(__d);
    return __d;
  }

  _LIBCPP_HIDE_FROM_ABI _Tp fetch_add(_Tp __op, memory_order __m = memory_order_seq_cst) volatile noexcept
    requires __base::is_always_lock_free
  {
    return __fetch_add(*this, __op, __m);
  }

  _LIBCPP_HIDE_FROM_ABI _Tp fetch_add(_Tp __op, memory_order __m = memory_order_seq_cst) noexcept {
    return __fetch_add(*this, __op, __m);
  }

  _LIBCPP_HIDE_FROM_ABI _Tp fetch_sub(_Tp __op, memory_order __m = memory_order_seq_cst) volatile noexcept
    requires __base::is_always_lock_free
  {
    return __fetch_sub(*this, __op, __m);
  }

  _LIBCPP_HIDE_FROM_ABI _Tp fetch_sub(_Tp __op, memory_order __m = memory_order_seq_cst) noexcept {
    return __fetch_sub(*this, __op, __m);
  }

  _LIBCPP_HIDE_FROM_ABI _Tp operator+=(_Tp __op) volatile noexcept
    requires __base::is_always_lock_free
  {
    return fetch_add(__op) + __op;
  }

  _LIBCPP_HIDE_FROM_ABI _Tp operator+=(_Tp __op) noexcept { return fetch_add(__op) + __op; }

  _LIBCPP_HIDE_FROM_ABI _Tp operator-=(_Tp __op) volatile noexcept
    requires __base::is_always_lock_free
  {
    return fetch_sub(__op) - __op;
  }

  _LIBCPP_HIDE_FROM_ABI _Tp operator-=(_Tp __op) noexcept { return fetch_sub(__op) - __op; }
};

#endif // _LIBCPP_STD_VER >= 20

// atomic_is_lock_free

template <class _Tp>
_LIBCPP_HIDE_FROM_ABI bool atomic_is_lock_free(const volatile atomic<_Tp>* __o) _NOEXCEPT {
  return __o->is_lock_free();
}

template <class _Tp>
_LIBCPP_HIDE_FROM_ABI bool atomic_is_lock_free(const atomic<_Tp>* __o) _NOEXCEPT {
  return __o->is_lock_free();
}

// atomic_init

template <class _Tp>
_LIBCPP_DEPRECATED_IN_CXX20 _LIBCPP_HIDE_FROM_ABI void
atomic_init(volatile atomic<_Tp>* __o, typename atomic<_Tp>::value_type __d) _NOEXCEPT {
  std::__cxx_atomic_init(std::addressof(__o->__a_), __d);
}

template <class _Tp>
_LIBCPP_DEPRECATED_IN_CXX20 _LIBCPP_HIDE_FROM_ABI void
atomic_init(atomic<_Tp>* __o, typename atomic<_Tp>::value_type __d) _NOEXCEPT {
  std::__cxx_atomic_init(std::addressof(__o->__a_), __d);
}

// atomic_store

template <class _Tp>
_LIBCPP_HIDE_FROM_ABI void atomic_store(volatile atomic<_Tp>* __o, typename atomic<_Tp>::value_type __d) _NOEXCEPT {
  __o->store(__d);
}

template <class _Tp>
_LIBCPP_HIDE_FROM_ABI void atomic_store(atomic<_Tp>* __o, typename atomic<_Tp>::value_type __d) _NOEXCEPT {
  __o->store(__d);
}

// atomic_store_explicit

template <class _Tp>
_LIBCPP_HIDE_FROM_ABI void
atomic_store_explicit(volatile atomic<_Tp>* __o, typename atomic<_Tp>::value_type __d, memory_order __m) _NOEXCEPT
    _LIBCPP_CHECK_STORE_MEMORY_ORDER(__m) {
  __o->store(__d, __m);
}

template <class _Tp>
_LIBCPP_HIDE_FROM_ABI void
atomic_store_explicit(atomic<_Tp>* __o, typename atomic<_Tp>::value_type __d, memory_order __m) _NOEXCEPT
    _LIBCPP_CHECK_STORE_MEMORY_ORDER(__m) {
  __o->store(__d, __m);
}

// atomic_load

template <class _Tp>
_LIBCPP_HIDE_FROM_ABI _Tp atomic_load(const volatile atomic<_Tp>* __o) _NOEXCEPT {
  return __o->load();
}

template <class _Tp>
_LIBCPP_HIDE_FROM_ABI _Tp atomic_load(const atomic<_Tp>* __o) _NOEXCEPT {
  return __o->load();
}

// atomic_load_explicit

template <class _Tp>
_LIBCPP_HIDE_FROM_ABI _Tp atomic_load_explicit(const volatile atomic<_Tp>* __o, memory_order __m) _NOEXCEPT
    _LIBCPP_CHECK_LOAD_MEMORY_ORDER(__m) {
  return __o->load(__m);
}

template <class _Tp>
_LIBCPP_HIDE_FROM_ABI _Tp atomic_load_explicit(const atomic<_Tp>* __o, memory_order __m) _NOEXCEPT
    _LIBCPP_CHECK_LOAD_MEMORY_ORDER(__m) {
  return __o->load(__m);
}

// atomic_exchange

template <class _Tp>
_LIBCPP_HIDE_FROM_ABI _Tp atomic_exchange(volatile atomic<_Tp>* __o, typename atomic<_Tp>::value_type __d) _NOEXCEPT {
  return __o->exchange(__d);
}

template <class _Tp>
_LIBCPP_HIDE_FROM_ABI _Tp atomic_exchange(atomic<_Tp>* __o, typename atomic<_Tp>::value_type __d) _NOEXCEPT {
  return __o->exchange(__d);
}

// atomic_exchange_explicit

template <class _Tp>
_LIBCPP_HIDE_FROM_ABI _Tp
atomic_exchange_explicit(volatile atomic<_Tp>* __o, typename atomic<_Tp>::value_type __d, memory_order __m) _NOEXCEPT {
  return __o->exchange(__d, __m);
}

template <class _Tp>
_LIBCPP_HIDE_FROM_ABI _Tp
atomic_exchange_explicit(atomic<_Tp>* __o, typename atomic<_Tp>::value_type __d, memory_order __m) _NOEXCEPT {
  return __o->exchange(__d, __m);
}

// atomic_compare_exchange_weak

template <class _Tp>
_LIBCPP_HIDE_FROM_ABI bool atomic_compare_exchange_weak(
    volatile atomic<_Tp>* __o, typename atomic<_Tp>::value_type* __e, typename atomic<_Tp>::value_type __d) _NOEXCEPT {
  return __o->compare_exchange_weak(*__e, __d);
}

template <class _Tp>
_LIBCPP_HIDE_FROM_ABI bool atomic_compare_exchange_weak(
    atomic<_Tp>* __o, typename atomic<_Tp>::value_type* __e, typename atomic<_Tp>::value_type __d) _NOEXCEPT {
  return __o->compare_exchange_weak(*__e, __d);
}

// atomic_compare_exchange_strong

template <class _Tp>
_LIBCPP_HIDE_FROM_ABI bool atomic_compare_exchange_strong(
    volatile atomic<_Tp>* __o, typename atomic<_Tp>::value_type* __e, typename atomic<_Tp>::value_type __d) _NOEXCEPT {
  return __o->compare_exchange_strong(*__e, __d);
}

template <class _Tp>
_LIBCPP_HIDE_FROM_ABI bool atomic_compare_exchange_strong(
    atomic<_Tp>* __o, typename atomic<_Tp>::value_type* __e, typename atomic<_Tp>::value_type __d) _NOEXCEPT {
  return __o->compare_exchange_strong(*__e, __d);
}

// atomic_compare_exchange_weak_explicit

template <class _Tp>
_LIBCPP_HIDE_FROM_ABI bool atomic_compare_exchange_weak_explicit(
    volatile atomic<_Tp>* __o,
    typename atomic<_Tp>::value_type* __e,
    typename atomic<_Tp>::value_type __d,
    memory_order __s,
    memory_order __f) _NOEXCEPT _LIBCPP_CHECK_EXCHANGE_MEMORY_ORDER(__s, __f) {
  return __o->compare_exchange_weak(*__e, __d, __s, __f);
}

template <class _Tp>
_LIBCPP_HIDE_FROM_ABI bool atomic_compare_exchange_weak_explicit(
    atomic<_Tp>* __o,
    typename atomic<_Tp>::value_type* __e,
    typename atomic<_Tp>::value_type __d,
    memory_order __s,
    memory_order __f) _NOEXCEPT _LIBCPP_CHECK_EXCHANGE_MEMORY_ORDER(__s, __f) {
  return __o->compare_exchange_weak(*__e, __d, __s, __f);
}

// atomic_compare_exchange_strong_explicit

template <class _Tp>
_LIBCPP_HIDE_FROM_ABI bool atomic_compare_exchange_strong_explicit(
    volatile atomic<_Tp>* __o,
    typename atomic<_Tp>::value_type* __e,
    typename atomic<_Tp>::value_type __d,
    memory_order __s,
    memory_order __f) _NOEXCEPT _LIBCPP_CHECK_EXCHANGE_MEMORY_ORDER(__s, __f) {
  return __o->compare_exchange_strong(*__e, __d, __s, __f);
}

template <class _Tp>
_LIBCPP_HIDE_FROM_ABI bool atomic_compare_exchange_strong_explicit(
    atomic<_Tp>* __o,
    typename atomic<_Tp>::value_type* __e,
    typename atomic<_Tp>::value_type __d,
    memory_order __s,
    memory_order __f) _NOEXCEPT _LIBCPP_CHECK_EXCHANGE_MEMORY_ORDER(__s, __f) {
  return __o->compare_exchange_strong(*__e, __d, __s, __f);
}

#if _LIBCPP_STD_VER >= 20

// atomic_wait

template <class _Tp>
_LIBCPP_HIDE_FROM_ABI void
atomic_wait(const volatile atomic<_Tp>* __o, typename atomic<_Tp>::value_type __v) _NOEXCEPT {
  return __o->wait(__v);
}

template <class _Tp>
_LIBCPP_HIDE_FROM_ABI void atomic_wait(const atomic<_Tp>* __o, typename atomic<_Tp>::value_type __v) _NOEXCEPT {
  return __o->wait(__v);
}

// atomic_wait_explicit

template <class _Tp>
_LIBCPP_HIDE_FROM_ABI void
atomic_wait_explicit(const volatile atomic<_Tp>* __o, typename atomic<_Tp>::value_type __v, memory_order __m) _NOEXCEPT
    _LIBCPP_CHECK_LOAD_MEMORY_ORDER(__m) {
  return __o->wait(__v, __m);
}

template <class _Tp>
_LIBCPP_HIDE_FROM_ABI void
atomic_wait_explicit(const atomic<_Tp>* __o, typename atomic<_Tp>::value_type __v, memory_order __m) _NOEXCEPT
    _LIBCPP_CHECK_LOAD_MEMORY_ORDER(__m) {
  return __o->wait(__v, __m);
}

// atomic_notify_one

template <class _Tp>
_LIBCPP_HIDE_FROM_ABI void atomic_notify_one(volatile atomic<_Tp>* __o) _NOEXCEPT {
  __o->notify_one();
}
template <class _Tp>
_LIBCPP_HIDE_FROM_ABI void atomic_notify_one(atomic<_Tp>* __o) _NOEXCEPT {
  __o->notify_one();
}

// atomic_notify_all

template <class _Tp>
_LIBCPP_HIDE_FROM_ABI void atomic_notify_all(volatile atomic<_Tp>* __o) _NOEXCEPT {
  __o->notify_all();
}
template <class _Tp>
_LIBCPP_HIDE_FROM_ABI void atomic_notify_all(atomic<_Tp>* __o) _NOEXCEPT {
  __o->notify_all();
}

#endif // _LIBCPP_STD_VER >= 20

// atomic_fetch_add

template <class _Tp>
_LIBCPP_HIDE_FROM_ABI _Tp
atomic_fetch_add(volatile atomic<_Tp>* __o, typename atomic<_Tp>::difference_type __op) _NOEXCEPT {
  return __o->fetch_add(__op);
}

template <class _Tp>
_LIBCPP_HIDE_FROM_ABI _Tp atomic_fetch_add(atomic<_Tp>* __o, typename atomic<_Tp>::difference_type __op) _NOEXCEPT {
  return __o->fetch_add(__op);
}

// atomic_fetch_add_explicit

template <class _Tp>
_LIBCPP_HIDE_FROM_ABI _Tp atomic_fetch_add_explicit(
    volatile atomic<_Tp>* __o, typename atomic<_Tp>::difference_type __op, memory_order __m) _NOEXCEPT {
  return __o->fetch_add(__op, __m);
}

template <class _Tp>
_LIBCPP_HIDE_FROM_ABI _Tp
atomic_fetch_add_explicit(atomic<_Tp>* __o, typename atomic<_Tp>::difference_type __op, memory_order __m) _NOEXCEPT {
  return __o->fetch_add(__op, __m);
}

// atomic_fetch_sub

template <class _Tp>
_LIBCPP_HIDE_FROM_ABI _Tp
atomic_fetch_sub(volatile atomic<_Tp>* __o, typename atomic<_Tp>::difference_type __op) _NOEXCEPT {
  return __o->fetch_sub(__op);
}

template <class _Tp>
_LIBCPP_HIDE_FROM_ABI _Tp atomic_fetch_sub(atomic<_Tp>* __o, typename atomic<_Tp>::difference_type __op) _NOEXCEPT {
  return __o->fetch_sub(__op);
}

// atomic_fetch_sub_explicit

template <class _Tp>
_LIBCPP_HIDE_FROM_ABI _Tp atomic_fetch_sub_explicit(
    volatile atomic<_Tp>* __o, typename atomic<_Tp>::difference_type __op, memory_order __m) _NOEXCEPT {
  return __o->fetch_sub(__op, __m);
}

template <class _Tp>
_LIBCPP_HIDE_FROM_ABI _Tp
atomic_fetch_sub_explicit(atomic<_Tp>* __o, typename atomic<_Tp>::difference_type __op, memory_order __m) _NOEXCEPT {
  return __o->fetch_sub(__op, __m);
}

// atomic_fetch_and

template <class _Tp, __enable_if_t<is_integral<_Tp>::value && !is_same<_Tp, bool>::value, int> = 0>
_LIBCPP_HIDE_FROM_ABI _Tp atomic_fetch_and(volatile atomic<_Tp>* __o, typename atomic<_Tp>::value_type __op) _NOEXCEPT {
  return __o->fetch_and(__op);
}

template <class _Tp, __enable_if_t<is_integral<_Tp>::value && !is_same<_Tp, bool>::value, int> = 0>
_LIBCPP_HIDE_FROM_ABI _Tp atomic_fetch_and(atomic<_Tp>* __o, typename atomic<_Tp>::value_type __op) _NOEXCEPT {
  return __o->fetch_and(__op);
}

// atomic_fetch_and_explicit

template <class _Tp, __enable_if_t<is_integral<_Tp>::value && !is_same<_Tp, bool>::value, int> = 0>
_LIBCPP_HIDE_FROM_ABI _Tp atomic_fetch_and_explicit(
    volatile atomic<_Tp>* __o, typename atomic<_Tp>::value_type __op, memory_order __m) _NOEXCEPT {
  return __o->fetch_and(__op, __m);
}

template <class _Tp, __enable_if_t<is_integral<_Tp>::value && !is_same<_Tp, bool>::value, int> = 0>
_LIBCPP_HIDE_FROM_ABI _Tp
atomic_fetch_and_explicit(atomic<_Tp>* __o, typename atomic<_Tp>::value_type __op, memory_order __m) _NOEXCEPT {
  return __o->fetch_and(__op, __m);
}

// atomic_fetch_or

template <class _Tp, __enable_if_t<is_integral<_Tp>::value && !is_same<_Tp, bool>::value, int> = 0>
_LIBCPP_HIDE_FROM_ABI _Tp atomic_fetch_or(volatile atomic<_Tp>* __o, typename atomic<_Tp>::value_type __op) _NOEXCEPT {
  return __o->fetch_or(__op);
}

template <class _Tp, __enable_if_t<is_integral<_Tp>::value && !is_same<_Tp, bool>::value, int> = 0>
_LIBCPP_HIDE_FROM_ABI _Tp atomic_fetch_or(atomic<_Tp>* __o, typename atomic<_Tp>::value_type __op) _NOEXCEPT {
  return __o->fetch_or(__op);
}

// atomic_fetch_or_explicit

template <class _Tp, __enable_if_t<is_integral<_Tp>::value && !is_same<_Tp, bool>::value, int> = 0>
_LIBCPP_HIDE_FROM_ABI _Tp
atomic_fetch_or_explicit(volatile atomic<_Tp>* __o, typename atomic<_Tp>::value_type __op, memory_order __m) _NOEXCEPT {
  return __o->fetch_or(__op, __m);
}

template <class _Tp, __enable_if_t<is_integral<_Tp>::value && !is_same<_Tp, bool>::value, int> = 0>
_LIBCPP_HIDE_FROM_ABI _Tp
atomic_fetch_or_explicit(atomic<_Tp>* __o, typename atomic<_Tp>::value_type __op, memory_order __m) _NOEXCEPT {
  return __o->fetch_or(__op, __m);
}

// atomic_fetch_xor

template <class _Tp, __enable_if_t<is_integral<_Tp>::value && !is_same<_Tp, bool>::value, int> = 0>
_LIBCPP_HIDE_FROM_ABI _Tp atomic_fetch_xor(volatile atomic<_Tp>* __o, typename atomic<_Tp>::value_type __op) _NOEXCEPT {
  return __o->fetch_xor(__op);
}

template <class _Tp, __enable_if_t<is_integral<_Tp>::value && !is_same<_Tp, bool>::value, int> = 0>
_LIBCPP_HIDE_FROM_ABI _Tp atomic_fetch_xor(atomic<_Tp>* __o, typename atomic<_Tp>::value_type __op) _NOEXCEPT {
  return __o->fetch_xor(__op);
}

// atomic_fetch_xor_explicit

template <class _Tp, __enable_if_t<is_integral<_Tp>::value && !is_same<_Tp, bool>::value, int> = 0>
_LIBCPP_HIDE_FROM_ABI _Tp atomic_fetch_xor_explicit(
    volatile atomic<_Tp>* __o, typename atomic<_Tp>::value_type __op, memory_order __m) _NOEXCEPT {
  return __o->fetch_xor(__op, __m);
}

template <class _Tp, __enable_if_t<is_integral<_Tp>::value && !is_same<_Tp, bool>::value, int> = 0>
_LIBCPP_HIDE_FROM_ABI _Tp
atomic_fetch_xor_explicit(atomic<_Tp>* __o, typename atomic<_Tp>::value_type __op, memory_order __m) _NOEXCEPT {
  return __o->fetch_xor(__op, __m);
}

_LIBCPP_END_NAMESPACE_STD

#endif // _LIBCPP___ATOMIC_ATOMIC_H