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 <__utility/pair.h>
15 #include <cstddef>
16 #include <new>
17
18 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
19 # pragma GCC system_header
20 #endif
21
22 _LIBCPP_BEGIN_NAMESPACE_STD
23
24 template <class _Tp>
25 _LIBCPP_NODISCARD _LIBCPP_HIDE_FROM_ABI _LIBCPP_NO_CFI _LIBCPP_DEPRECATED_IN_CXX17 pair<_Tp*, ptrdiff_t>
get_temporary_buffer(ptrdiff_t __n)26 get_temporary_buffer(ptrdiff_t __n) _NOEXCEPT {
27 pair<_Tp*, ptrdiff_t> __r(0, 0);
28 const ptrdiff_t __m =
29 (~ptrdiff_t(0) ^ ptrdiff_t(ptrdiff_t(1) << (sizeof(ptrdiff_t) * __CHAR_BIT__ - 1))) / sizeof(_Tp);
30 if (__n > __m)
31 __n = __m;
32 while (__n > 0) {
33 #if !defined(_LIBCPP_HAS_NO_ALIGNED_ALLOCATION)
34 if (__is_overaligned_for_new(_LIBCPP_ALIGNOF(_Tp))) {
35 align_val_t __al = align_val_t(_LIBCPP_ALIGNOF(_Tp));
36 __r.first = static_cast<_Tp*>(::operator new(__n * sizeof(_Tp), __al, nothrow));
37 } else {
38 __r.first = static_cast<_Tp*>(::operator new(__n * sizeof(_Tp), nothrow));
39 }
40 #else
41 if (__is_overaligned_for_new(_LIBCPP_ALIGNOF(_Tp))) {
42 // Since aligned operator new is unavailable, return an empty
43 // buffer rather than one with invalid alignment.
44 return __r;
45 }
46
47 __r.first = static_cast<_Tp*>(::operator new(__n * sizeof(_Tp), nothrow));
48 #endif
49
50 if (__r.first) {
51 __r.second = __n;
52 break;
53 }
54 __n /= 2;
55 }
56 return __r;
57 }
58
59 template <class _Tp>
return_temporary_buffer(_Tp * __p)60 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_DEPRECATED_IN_CXX17 void return_temporary_buffer(_Tp* __p) _NOEXCEPT {
61 std::__libcpp_deallocate_unsized((void*)__p, _LIBCPP_ALIGNOF(_Tp));
62 }
63
64 struct __return_temporary_buffer {
65 _LIBCPP_SUPPRESS_DEPRECATED_PUSH
66 template <class _Tp>
operator__return_temporary_buffer67 _LIBCPP_HIDE_FROM_ABI void operator()(_Tp* __p) const {
68 std::return_temporary_buffer(__p);
69 }
70 _LIBCPP_SUPPRESS_DEPRECATED_POP
71 };
72
73 _LIBCPP_END_NAMESPACE_STD
74
75 #endif // _LIBCPP___MEMORY_TEMPORARY_BUFFER_H
76