34d4f0c136
We've built up quite a few links directly to github within the code base. We should instead use `llvm.org/PR<issue-number>` to link to bugs, since that is resilient to the bug tracker changing in the future. This is especially relevant for tests linking to bugs, since they will probably be there for decades to come. A nice side effect is that these links are significantly shorter than the GH links, making them much less of an eyesore. This patch also replaces a few links that linked to the old bugzilla instance on llvm.org.
137 lines
7.7 KiB
C++
137 lines
7.7 KiB
C++
// -*- C++ -*-
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//===----------------------------------------------------------------------===//
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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___MEMORY_COMPRESSED_PAIR_H
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#define _LIBCPP___MEMORY_COMPRESSED_PAIR_H
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#include <__config>
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#include <__cstddef/size_t.h>
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#include <__type_traits/datasizeof.h>
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#include <__type_traits/is_empty.h>
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#include <__type_traits/is_final.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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// ================================================================================================================== //
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// The utilites here are for staying ABI compatible with the legacy `__compressed_pair`. They should not be used //
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// for new data structures. Use `_LIBCPP_NO_UNIQUE_ADDRESS` for new data structures instead (but make sure you //
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// understand how it works). //
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// ================================================================================================================== //
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// The first member is aligned to the alignment of the second member to force padding in front of the compressed pair
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// in case there are members before it.
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//
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// For example:
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// (assuming x86-64 linux)
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// class SomeClass {
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// uint32_t member1;
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// _LIBCPP_COMPRESSED_PAIR(uint32_t, member2, uint64_t, member3);
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// }
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//
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// The layout with __compressed_pair is:
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// member1 - offset: 0, size: 4
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// padding - offset: 4, size: 4
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// member2 - offset: 8, size: 4
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// padding - offset: 12, size: 4
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// member3 - offset: 16, size: 8
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//
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// If the [[gnu::aligned]] wasn't there, the layout would instead be:
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// member1 - offset: 0, size: 4
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// member2 - offset: 4, size: 4
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// member3 - offset: 8, size: 8
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//
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// Furthermore, that alignment must be the same as what was used in the old __compressed_pair layout, so we must
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// handle reference types specially since alignof(T&) == alignof(T).
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// See https://llvm.org/PR118559.
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#ifndef _LIBCPP_ABI_NO_COMPRESSED_PAIR_PADDING
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template <class _Tp>
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inline const size_t __compressed_pair_alignment = _LIBCPP_ALIGNOF(_Tp);
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template <class _Tp>
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inline const size_t __compressed_pair_alignment<_Tp&> = _LIBCPP_ALIGNOF(void*);
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template <class _ToPad>
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inline const bool __is_reference_or_unpadded_object =
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(is_empty<_ToPad>::value && !__libcpp_is_final<_ToPad>::value) || sizeof(_ToPad) == __datasizeof_v<_ToPad>;
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template <class _Tp>
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inline const bool __is_reference_or_unpadded_object<_Tp&> = true;
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template <class _Tp>
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inline const bool __is_reference_or_unpadded_object<_Tp&&> = true;
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template <class _ToPad, bool _Empty = __is_reference_or_unpadded_object<_ToPad> >
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class __compressed_pair_padding {
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char __padding_[sizeof(_ToPad) - __datasizeof_v<_ToPad>] = {};
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};
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template <class _ToPad>
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class __compressed_pair_padding<_ToPad, true> {};
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// TODO: Fix the ABI for GCC as well once https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121637 is fixed
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# ifdef _LIBCPP_COMPILER_GCC
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# define _LIBCPP_COMPRESSED_PAIR(T1, Initializer1, T2, Initializer2) \
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_LIBCPP_NO_UNIQUE_ADDRESS __attribute__((__aligned__(::std::__compressed_pair_alignment<T2>))) T1 Initializer1; \
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_LIBCPP_NO_UNIQUE_ADDRESS ::std::__compressed_pair_padding<T1> _LIBCPP_CONCAT3(__padding1_, __LINE__, _); \
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_LIBCPP_NO_UNIQUE_ADDRESS T2 Initializer2; \
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_LIBCPP_NO_UNIQUE_ADDRESS ::std::__compressed_pair_padding<T2> _LIBCPP_CONCAT3(__padding2_, __LINE__, _)
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# define _LIBCPP_COMPRESSED_TRIPLE(T1, Initializer1, T2, Initializer2, T3, Initializer3) \
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_LIBCPP_NO_UNIQUE_ADDRESS \
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__attribute__((__aligned__(::std::__compressed_pair_alignment<T2>), \
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__aligned__(::std::__compressed_pair_alignment<T3>))) T1 Initializer1; \
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_LIBCPP_NO_UNIQUE_ADDRESS ::std::__compressed_pair_padding<T1> _LIBCPP_CONCAT3(__padding1_, __LINE__, _); \
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_LIBCPP_NO_UNIQUE_ADDRESS T2 Initializer2; \
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_LIBCPP_NO_UNIQUE_ADDRESS ::std::__compressed_pair_padding<T2> _LIBCPP_CONCAT3(__padding2_, __LINE__, _); \
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_LIBCPP_NO_UNIQUE_ADDRESS T3 Initializer3; \
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_LIBCPP_NO_UNIQUE_ADDRESS ::std::__compressed_pair_padding<T3> _LIBCPP_CONCAT3(__padding3_, __LINE__, _)
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# else
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# define _LIBCPP_COMPRESSED_PAIR(T1, Initializer1, T2, Initializer2) \
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struct { \
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_LIBCPP_NO_UNIQUE_ADDRESS \
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__attribute__((__aligned__(::std::__compressed_pair_alignment<T2>))) T1 Initializer1; \
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_LIBCPP_NO_UNIQUE_ADDRESS ::std::__compressed_pair_padding<T1> _LIBCPP_CONCAT3(__padding1_, __LINE__, _); \
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_LIBCPP_NO_UNIQUE_ADDRESS T2 Initializer2; \
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_LIBCPP_NO_UNIQUE_ADDRESS ::std::__compressed_pair_padding<T2> _LIBCPP_CONCAT3(__padding2_, __LINE__, _); \
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}
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# define _LIBCPP_COMPRESSED_TRIPLE(T1, Initializer1, T2, Initializer2, T3, Initializer3) \
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struct { \
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_LIBCPP_NO_UNIQUE_ADDRESS \
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__attribute__((__aligned__(::std::__compressed_pair_alignment<T2>), \
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__aligned__(::std::__compressed_pair_alignment<T3>))) T1 Initializer1; \
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_LIBCPP_NO_UNIQUE_ADDRESS ::std::__compressed_pair_padding<T1> _LIBCPP_CONCAT3(__padding1_, __LINE__, _); \
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_LIBCPP_NO_UNIQUE_ADDRESS T2 Initializer2; \
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_LIBCPP_NO_UNIQUE_ADDRESS ::std::__compressed_pair_padding<T2> _LIBCPP_CONCAT3(__padding2_, __LINE__, _); \
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_LIBCPP_NO_UNIQUE_ADDRESS T3 Initializer3; \
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_LIBCPP_NO_UNIQUE_ADDRESS ::std::__compressed_pair_padding<T3> _LIBCPP_CONCAT3(__padding3_, __LINE__, _); \
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}
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# endif
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#else
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# define _LIBCPP_COMPRESSED_PAIR(T1, Name1, T2, Name2) \
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_LIBCPP_NO_UNIQUE_ADDRESS T1 Name1; \
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_LIBCPP_NO_UNIQUE_ADDRESS T2 Name2
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# define _LIBCPP_COMPRESSED_TRIPLE(T1, Name1, T2, Name2, T3, Name3) \
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_LIBCPP_NO_UNIQUE_ADDRESS T1 Name1; \
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_LIBCPP_NO_UNIQUE_ADDRESS T2 Name2; \
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_LIBCPP_NO_UNIQUE_ADDRESS T3 Name3
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#endif // _LIBCPP_ABI_NO_COMPRESSED_PAIR_PADDING
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_LIBCPP_END_NAMESPACE_STD
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#endif // _LIBCPP___MEMORY_COMPRESSED_PAIR_H
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