47cca0288d
This adds missing includes to internal library headers which get included from more than one other header, so that they can be compiled as a stand-alone header unit. For existing use cases these includes are no-ops because they're already done by the header that includes these files. For compiling them as a header unit, this ensures that they include what they use. libstdc++-v3/ChangeLog: PR libstdc++/99413 * include/bits/align.h: Include debug/assertions.h. * include/bits/codecvt.h: Include bits/c++config.h. * include/bits/enable_special_members.h: Likewise. * include/bits/erase_if.h: Likewise. * include/bits/functional_hash.h: Include <type_traits>. * include/bits/invoke.h: Include bits/move.h. * include/bits/ostream_insert.h: Include bits/exception_defines.h. * include/bits/parse_numbers.h: Include <type_traits>. * include/bits/predefined_ops.h: Include bits/c++config.h. * include/bits/range_access.h: Include bits/stl_iterator.h. * include/bits/stl_bvector.h: Do not include bits/stl_vector.h. * include/bits/stl_iterator.h: Include bits/stl_iterator_base_types.h. * include/bits/stl_uninitialized.h: Include bits/stl_algobase.h. * include/bits/uniform_int_dist.h: Include bits/concept_check.h. * include/bits/unique_lock.h: Include bits/std_mutex.h. * include/debug/assertions.h: Include bits/c++config.h.
112 lines
3.6 KiB
C++
112 lines
3.6 KiB
C++
// align implementation -*- C++ -*-
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// Copyright (C) 2014-2021 Free Software Foundation, Inc.
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//
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// This file is part of the GNU ISO C++ Library. This library is free
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// software; you can redistribute it and/or modify it under the
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// terms of the GNU General Public License as published by the
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// Free Software Foundation; either version 3, or (at your option)
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// any later version.
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// Under Section 7 of GPL version 3, you are granted additional
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// permissions described in the GCC Runtime Library Exception, version
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// 3.1, as published by the Free Software Foundation.
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// You should have received a copy of the GNU General Public License and
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// a copy of the GCC Runtime Library Exception along with this program;
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// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
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// <http://www.gnu.org/licenses/>.
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/** @file bits/align.h
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* This is an internal header file, included by other library headers.
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* Do not attempt to use it directly. @headername{memory}
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*/
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#ifndef _GLIBCXX_ALIGN_H
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#define _GLIBCXX_ALIGN_H 1
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#include <bits/c++config.h>
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#include <bit> // std::has_single_bit
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#include <stdint.h> // uintptr_t
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#include <debug/assertions.h> // _GLIBCXX_DEBUG_ASSERT
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namespace std _GLIBCXX_VISIBILITY(default)
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{
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_GLIBCXX_BEGIN_NAMESPACE_VERSION
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/**
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* @brief Fit aligned storage in buffer.
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*
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* This function tries to fit @a __size bytes of storage with alignment
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* @a __align into the buffer @a __ptr of size @a __space bytes. If such
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* a buffer fits then @a __ptr is changed to point to the first byte of the
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* aligned storage and @a __space is reduced by the bytes used for alignment.
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*
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* C++11 20.6.5 [ptr.align]
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*
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* @param __align A fundamental or extended alignment value.
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* @param __size Size of the aligned storage required.
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* @param __ptr Pointer to a buffer of @a __space bytes.
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* @param __space Size of the buffer pointed to by @a __ptr.
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* @return the updated pointer if the aligned storage fits, otherwise nullptr.
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*
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* @ingroup memory
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*/
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inline void*
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align(size_t __align, size_t __size, void*& __ptr, size_t& __space) noexcept
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{
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if (__space < __size)
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return nullptr;
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const auto __intptr = reinterpret_cast<uintptr_t>(__ptr);
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const auto __aligned = (__intptr - 1u + __align) & -__align;
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const auto __diff = __aligned - __intptr;
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if (__diff > (__space - __size))
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return nullptr;
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else
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{
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__space -= __diff;
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return __ptr = reinterpret_cast<void*>(__aligned);
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}
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}
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#if __cplusplus > 201703L
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#define __cpp_lib_assume_aligned 201811L
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/** @brief Inform the compiler that a pointer is aligned.
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*
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* @tparam _Align An alignment value (i.e. a power of two)
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* @tparam _Tp An object type
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* @param __ptr A pointer that is aligned to _Align
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*
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* C++20 20.10.6 [ptr.align]
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*
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* @ingroup memory
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*/
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template<size_t _Align, class _Tp>
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[[nodiscard,__gnu__::__always_inline__]]
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constexpr _Tp*
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assume_aligned(_Tp* __ptr) noexcept
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{
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static_assert(std::has_single_bit(_Align));
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if (std::is_constant_evaluated())
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return __ptr;
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else
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{
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// This function is expected to be used in hot code, where
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// __glibcxx_assert would add unwanted overhead.
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_GLIBCXX_DEBUG_ASSERT((uintptr_t)__ptr % _Align == 0);
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return static_cast<_Tp*>(__builtin_assume_aligned(__ptr, _Align));
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}
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}
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#endif // C++2a
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_GLIBCXX_END_NAMESPACE_VERSION
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} // namespace
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#endif /* _GLIBCXX_ALIGN_H */
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