1 //===----------------------------------------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8
9 #ifndef _LIBCPP___MEMORY_ALIGNED_ALLOC_H
10 #define _LIBCPP___MEMORY_ALIGNED_ALLOC_H
11
12 #include <__config>
13 #include <cstddef>
14 #include <cstdlib>
15
16 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
17 # pragma GCC system_header
18 #endif
19
20 _LIBCPP_BEGIN_NAMESPACE_STD
21
22 #ifndef _LIBCPP_HAS_NO_LIBRARY_ALIGNED_ALLOCATION
23
24 // Low-level helpers to call the aligned allocation and deallocation functions
25 // on the target platform. This is used to implement libc++'s own memory
26 // allocation routines -- if you need to allocate memory inside the library,
27 // chances are that you want to use `__libcpp_allocate` instead.
28 //
29 // Returns the allocated memory, or `nullptr` on failure.
__libcpp_aligned_alloc(std::size_t __alignment,std::size_t __size)30 inline _LIBCPP_HIDE_FROM_ABI void* __libcpp_aligned_alloc(std::size_t __alignment, std::size_t __size) {
31 # if defined(_LIBCPP_MSVCRT_LIKE)
32 return ::_aligned_malloc(__size, __alignment);
33 # elif _LIBCPP_STD_VER >= 17 && !defined(_LIBCPP_HAS_NO_C11_ALIGNED_ALLOC)
34 // aligned_alloc() requires that __size is a multiple of __alignment,
35 // but for C++ [new.delete.general], only states "if the value of an
36 // alignment argument passed to any of these functions is not a valid
37 // alignment value, the behavior is undefined".
38 // To handle calls such as ::operator new(1, std::align_val_t(128)), we
39 // round __size up to the next multiple of __alignment.
40 size_t __rounded_size = (__size + __alignment - 1) & ~(__alignment - 1);
41 // Rounding up could have wrapped around to zero, so we have to add another
42 // max() ternary to the actual call site to avoid succeeded in that case.
43 return ::aligned_alloc(__alignment, __size > __rounded_size ? __size : __rounded_size);
44 # else
45 void* __result = nullptr;
46 (void)::posix_memalign(&__result, __alignment, __size);
47 // If posix_memalign fails, __result is unmodified so we still return `nullptr`.
48 return __result;
49 # endif
50 }
51
__libcpp_aligned_free(void * __ptr)52 inline _LIBCPP_HIDE_FROM_ABI void __libcpp_aligned_free(void* __ptr) {
53 # if defined(_LIBCPP_MSVCRT_LIKE)
54 ::_aligned_free(__ptr);
55 # else
56 ::free(__ptr);
57 # endif
58 }
59
60 #endif // !_LIBCPP_HAS_NO_LIBRARY_ALIGNED_ALLOCATION
61
62 _LIBCPP_END_NAMESPACE_STD
63
64 #endif // _LIBCPP___MEMORY_ALIGNED_ALLOC_H
65