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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