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64 lines
2.5 KiB
C++
64 lines
2.5 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___MEMORY_ALIGNED_ALLOC_H
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#define _LIBCPP___MEMORY_ALIGNED_ALLOC_H
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#include <__config>
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#include <cstddef>
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#include <cstdlib>
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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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#ifndef _LIBCPP_HAS_NO_LIBRARY_ALIGNED_ALLOCATION
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// Low-level helpers to call the aligned allocation and deallocation functions
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// on the target platform. This is used to implement libc++'s own memory
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// allocation routines -- if you need to allocate memory inside the library,
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// chances are that you want to use `__libcpp_allocate` instead.
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//
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// Returns the allocated memory, or `nullptr` on failure.
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inline _LIBCPP_HIDE_FROM_ABI void* __libcpp_aligned_alloc(std::size_t __alignment, std::size_t __size) {
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# if defined(_LIBCPP_MSVCRT_LIKE)
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return ::_aligned_malloc(__size, __alignment);
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# elif _LIBCPP_STD_VER >= 17 && !defined(_LIBCPP_HAS_NO_C11_ALIGNED_ALLOC)
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// aligned_alloc() requires that __size is a multiple of __alignment,
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// but for C++ [new.delete.general], only states "if the value of an
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// alignment argument passed to any of these functions is not a valid
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// alignment value, the behavior is undefined".
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// To handle calls such as ::operator new(1, std::align_val_t(128)), we
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// round __size up to the next multiple of __alignment.
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size_t __rounded_size = (__size + __alignment - 1) & ~(__alignment - 1);
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// Rounding up could have wrapped around to zero, so we have to add another
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// max() ternary to the actual call site to avoid succeeded in that case.
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return ::aligned_alloc(__alignment, __size > __rounded_size ? __size : __rounded_size);
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# else
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void* __result = nullptr;
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(void)::posix_memalign(&__result, __alignment, __size);
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// If posix_memalign fails, __result is unmodified so we still return `nullptr`.
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return __result;
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# endif
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}
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inline _LIBCPP_HIDE_FROM_ABI void __libcpp_aligned_free(void* __ptr) {
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# if defined(_LIBCPP_MSVCRT_LIKE)
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::_aligned_free(__ptr);
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# else
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::free(__ptr);
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# endif
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}
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#endif // !_LIBCPP_HAS_NO_LIBRARY_ALIGNED_ALLOCATION
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_LIBCPP_END_NAMESPACE_STD
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#endif // _LIBCPP___MEMORY_ALIGNED_ALLOC_H
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