368faacac7
This commit reverts 5aaefa51 (and also partly 7f285f48e77 and b6d75682f9, which were related to the original commit). As landed, 5aaefa51 had unintended consequences on some downstream bots and didn't have proper coverage upstream due to a few subtle things. Implementing this is something we should do in libc++, however we'll first need to address a few issues listed in https://reviews.llvm.org/D106124#3349710. Differential Revision: https://reviews.llvm.org/D120683
85 lines
2.4 KiB
C++
85 lines
2.4 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_TEMPORARY_BUFFER_H
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#define _LIBCPP___MEMORY_TEMPORARY_BUFFER_H
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#include <__config>
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#include <__utility/pair.h>
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#include <cstddef>
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#include <new>
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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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template <class _Tp>
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_LIBCPP_NODISCARD_EXT _LIBCPP_NO_CFI
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pair<_Tp*, ptrdiff_t>
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get_temporary_buffer(ptrdiff_t __n) _NOEXCEPT
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{
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pair<_Tp*, ptrdiff_t> __r(0, 0);
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const ptrdiff_t __m = (~ptrdiff_t(0) ^
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ptrdiff_t(ptrdiff_t(1) << (sizeof(ptrdiff_t) * __CHAR_BIT__ - 1)))
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/ sizeof(_Tp);
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if (__n > __m)
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__n = __m;
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while (__n > 0)
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{
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#if !defined(_LIBCPP_HAS_NO_ALIGNED_ALLOCATION)
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if (__is_overaligned_for_new(_LIBCPP_ALIGNOF(_Tp)))
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{
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align_val_t __al =
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align_val_t(alignment_of<_Tp>::value);
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__r.first = static_cast<_Tp*>(::operator new(
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__n * sizeof(_Tp), __al, nothrow));
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} else {
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__r.first = static_cast<_Tp*>(::operator new(
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__n * sizeof(_Tp), nothrow));
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}
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#else
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if (__is_overaligned_for_new(_LIBCPP_ALIGNOF(_Tp)))
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{
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// Since aligned operator new is unavailable, return an empty
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// buffer rather than one with invalid alignment.
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return __r;
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}
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__r.first = static_cast<_Tp*>(::operator new(__n * sizeof(_Tp), nothrow));
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#endif
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if (__r.first)
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{
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__r.second = __n;
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break;
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}
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__n /= 2;
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}
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return __r;
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}
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template <class _Tp>
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inline _LIBCPP_INLINE_VISIBILITY
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void return_temporary_buffer(_Tp* __p) _NOEXCEPT
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{
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_VSTD::__libcpp_deallocate_unsized((void*)__p, _LIBCPP_ALIGNOF(_Tp));
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}
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struct __return_temporary_buffer
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{
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template <class _Tp>
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_LIBCPP_INLINE_VISIBILITY void operator()(_Tp* __p) const {_VSTD::return_temporary_buffer(__p);}
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};
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_LIBCPP_END_NAMESPACE_STD
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#endif // _LIBCPP___MEMORY_TEMPORARY_BUFFER_H
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