ad2fbea797
This has the benefit of consistent placement for these macros (outside the namespace, not inside it). This, in turn, makes it more obvious that the condition applies to the entire namespace scope. Compile times are also reduced a bit, since the compiler doesn't have to open a namespace just to close it again. This is enforced with a clang-tidy check. As a drive-by this also fixes a few macro comments.
101 lines
3.5 KiB
C++
101 lines
3.5 KiB
C++
//===----------------------------------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef _LIBCPP___ATOMIC_ATOMIC_WAITABLE_TRAITS_H
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#define _LIBCPP___ATOMIC_ATOMIC_WAITABLE_TRAITS_H
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#include <__atomic/contention_t.h>
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#include <__atomic/memory_order.h>
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#include <__config>
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#include <__type_traits/decay.h>
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#include <__type_traits/has_unique_object_representation.h>
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#include <__type_traits/is_same.h>
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#include <__type_traits/is_trivially_copyable.h>
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#include <cstring>
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#if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
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# pragma GCC system_header
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#endif
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#if _LIBCPP_STD_VER >= 20
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_LIBCPP_BEGIN_NAMESPACE_STD
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// The customisation points to enable the following functions:
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// - __atomic_wait
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// - __atomic_wait_unless
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// - __atomic_notify_one
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// - __atomic_notify_all
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template <class _Tp, class = void>
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struct __atomic_waitable_traits {
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using __value_type _LIBCPP_NODEBUG = void;
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template <class _AtomicWaitable>
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static void __atomic_load(_AtomicWaitable&&, memory_order) = delete;
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template <class _AtomicWaitable>
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static void __atomic_contention_address(_AtomicWaitable&&) = delete;
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};
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template <class _Tp>
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concept __atomic_waitable = requires(const _Tp __t, memory_order __order) {
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typename __atomic_waitable_traits<__decay_t<_Tp> >::__value_type;
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{ __atomic_waitable_traits<__decay_t<_Tp> >::__atomic_load(__t, __order) };
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{ __atomic_waitable_traits<__decay_t<_Tp> >::__atomic_contention_address(__t) };
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};
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# ifdef __linux__
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# define _LIBCPP_NATIVE_PLATFORM_WAIT_SIZES(_APPLY) _APPLY(4)
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# elif defined(__APPLE__)
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# define _LIBCPP_NATIVE_PLATFORM_WAIT_SIZES(_APPLY) \
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_APPLY(4) \
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_APPLY(8)
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# elif defined(__FreeBSD__) && __SIZEOF_LONG__ == 8
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# define _LIBCPP_NATIVE_PLATFORM_WAIT_SIZES(_APPLY) _APPLY(8)
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# elif defined(_WIN32)
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# define _LIBCPP_NATIVE_PLATFORM_WAIT_SIZES(_APPLY) _APPLY(8)
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# else
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# define _LIBCPP_NATIVE_PLATFORM_WAIT_SIZES(_APPLY) _APPLY(sizeof(__cxx_contention_t))
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# endif // __linux__
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// concepts defines the types are supported natively by the platform's wait
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# if defined(_LIBCPP_ABI_ATOMIC_WAIT_NATIVE_BY_SIZE)
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template <class _Tp>
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_LIBCPP_HIDE_FROM_ABI constexpr bool __has_native_atomic_wait_impl() {
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if (alignof(_Tp) % sizeof(_Tp) != 0)
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return false;
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switch (sizeof(_Tp)) {
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# define _LIBCPP_MAKE_CASE(n) \
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case n: \
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return true;
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_LIBCPP_NATIVE_PLATFORM_WAIT_SIZES(_LIBCPP_MAKE_CASE)
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default:
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return false;
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# undef _LIBCPP_MAKE_CASE
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};
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}
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template <class _Tp>
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concept __has_native_atomic_wait =
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has_unique_object_representations_v<_Tp> && is_trivially_copyable_v<_Tp> &&
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std::__has_native_atomic_wait_impl<_Tp>();
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# else // _LIBCPP_ABI_ATOMIC_WAIT_NATIVE_BY_SIZE
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template <class _Tp>
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concept __has_native_atomic_wait = is_same_v<_Tp, __cxx_contention_t>;
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# endif // _LIBCPP_ABI_ATOMIC_WAIT_NATIVE_BY_SIZE
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_LIBCPP_END_NAMESPACE_STD
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#endif // _LIBCPP_STD_VER >= 20
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#endif // _LIBCPP___ATOMIC_ATOMIC_WAITABLE_TRAITS_H
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