1 // -*- C++ -*-
2 //===----------------------------------------------------------------------===//
3 //
4 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
5 // See https://llvm.org/LICENSE.txt for license information.
6 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7 //
8 //===----------------------------------------------------------------------===//
9
10 #ifndef _LIBCPP___MEMORY_TEMPORARY_BUFFER_H
11 #define _LIBCPP___MEMORY_TEMPORARY_BUFFER_H
12
13 #include <__config>
14 #include <__type_traits/alignment_of.h>
15 #include <__utility/pair.h>
16 #include <cstddef>
17 #include <new>
18
19 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
20 # pragma GCC system_header
21 #endif
22
23 _LIBCPP_BEGIN_NAMESPACE_STD
24
25 template <class _Tp>
26 _LIBCPP_NODISCARD_EXT _LIBCPP_HIDE_FROM_ABI _LIBCPP_NO_CFI _LIBCPP_DEPRECATED_IN_CXX17
27 pair<_Tp*, ptrdiff_t>
get_temporary_buffer(ptrdiff_t __n)28 get_temporary_buffer(ptrdiff_t __n) _NOEXCEPT
29 {
30 pair<_Tp*, ptrdiff_t> __r(0, 0);
31 const ptrdiff_t __m = (~ptrdiff_t(0) ^
32 ptrdiff_t(ptrdiff_t(1) << (sizeof(ptrdiff_t) * __CHAR_BIT__ - 1)))
33 / sizeof(_Tp);
34 if (__n > __m)
35 __n = __m;
36 while (__n > 0)
37 {
38 #if !defined(_LIBCPP_HAS_NO_ALIGNED_ALLOCATION)
39 if (__is_overaligned_for_new(_LIBCPP_ALIGNOF(_Tp)))
40 {
41 align_val_t __al = align_val_t(_LIBCPP_ALIGNOF(_Tp));
42 __r.first = static_cast<_Tp*>(::operator new(
43 __n * sizeof(_Tp), __al, nothrow));
44 } else {
45 __r.first = static_cast<_Tp*>(::operator new(
46 __n * sizeof(_Tp), nothrow));
47 }
48 #else
49 if (__is_overaligned_for_new(_LIBCPP_ALIGNOF(_Tp)))
50 {
51 // Since aligned operator new is unavailable, return an empty
52 // buffer rather than one with invalid alignment.
53 return __r;
54 }
55
56 __r.first = static_cast<_Tp*>(::operator new(__n * sizeof(_Tp), nothrow));
57 #endif
58
59 if (__r.first)
60 {
61 __r.second = __n;
62 break;
63 }
64 __n /= 2;
65 }
66 return __r;
67 }
68
69 template <class _Tp>
70 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_DEPRECATED_IN_CXX17
return_temporary_buffer(_Tp * __p)71 void return_temporary_buffer(_Tp* __p) _NOEXCEPT
72 {
73 _VSTD::__libcpp_deallocate_unsized((void*)__p, _LIBCPP_ALIGNOF(_Tp));
74 }
75
76 struct __return_temporary_buffer
77 {
78 _LIBCPP_SUPPRESS_DEPRECATED_PUSH
79 template <class _Tp>
operator__return_temporary_buffer80 _LIBCPP_INLINE_VISIBILITY void operator()(_Tp* __p) const {_VSTD::return_temporary_buffer(__p);}
81 _LIBCPP_SUPPRESS_DEPRECATED_POP
82 };
83
84 _LIBCPP_END_NAMESPACE_STD
85
86 #endif // _LIBCPP___MEMORY_TEMPORARY_BUFFER_H
87