c1720822b6
Fix #135109 Clang is able to emit an `atomicrmw` instruction from the `__atomic_fetch_add` and `__atomic_fetch_sub` builtins on floating-point types.
56 lines
1.7 KiB
C++
56 lines
1.7 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_FLOATING_POINT_HELPER_H
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#define _LIBCPP___ATOMIC_FLOATING_POINT_HELPER_H
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#include <__config>
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#include <__type_traits/is_floating_point.h>
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#include <__type_traits/is_same.h>
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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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_LIBCPP_BEGIN_NAMESPACE_STD
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#if _LIBCPP_STD_VER >= 20
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template <class _Tp>
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_LIBCPP_HIDE_FROM_ABI constexpr bool __is_fp80_long_double() {
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// Only x87-fp80 long double has 64-bit mantissa
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return __LDBL_MANT_DIG__ == 64 && std::is_same_v<_Tp, long double>;
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}
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template <class _Tp>
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_LIBCPP_HIDE_FROM_ABI constexpr bool __has_rmw_builtin() {
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static_assert(std::is_floating_point_v<_Tp>);
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# ifndef _LIBCPP_COMPILER_CLANG_BASED
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return false;
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# else
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// The builtin __cxx_atomic_fetch_add errors during compilation for
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// long double on platforms with fp80 format.
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// For more details, see
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// lib/Sema/SemaChecking.cpp function IsAllowedValueType
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// LLVM Parser does not allow atomicrmw with x86_fp80 type.
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// if (ValType->isSpecificBuiltinType(BuiltinType::LongDouble) &&
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// &Context.getTargetInfo().getLongDoubleFormat() ==
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// &llvm::APFloat::x87DoubleExtended())
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// For more info
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// https://llvm.org/PR68602
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// https://reviews.llvm.org/D53965
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return !std::__is_fp80_long_double<_Tp>();
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# endif
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}
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#endif
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_LIBCPP_END_NAMESPACE_STD
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#endif // _LIBCPP___ATOMIC_FLOATING_POINT_HELPER_H
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