1 //===----------------------------------------------------------------------===//
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
7 //===----------------------------------------------------------------------===//
9 #ifndef _LIBCPP___TYPE_TRAITS_ALIGNED_STORAGE_H
10 #define _LIBCPP___TYPE_TRAITS_ALIGNED_STORAGE_H
13 #include <__type_traits/conditional.h>
14 #include <__type_traits/integral_constant.h>
15 #include <__type_traits/nat.h>
16 #include <__type_traits/type_list.h>
19 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
20 # pragma GCC system_header
23 _LIBCPP_BEGIN_NAMESPACE_STD
27 static const size_t value = _LIBCPP_PREFERRED_ALIGNOF(_Tp);
31 struct __struct_double {
34 struct __struct_double4 {
39 typedef __type_list<__align_type<unsigned char>,
40 __type_list<__align_type<unsigned short>,
41 __type_list<__align_type<unsigned int>,
42 __type_list<__align_type<unsigned long>,
43 __type_list<__align_type<unsigned long long>,
44 __type_list<__align_type<double>,
45 __type_list<__align_type<long double>,
46 __type_list<__align_type<__struct_double>,
47 __type_list<__align_type<__struct_double4>,
48 __type_list<__align_type<int*>,
50 > > > > > > > > > > __all_types;
53 template <size_t _Align>
54 struct _ALIGNAS(_Align) __fallback_overaligned {};
56 template <class _TL, size_t _Align>
59 template <class _Hp, size_t _Align>
60 struct __find_pod<__type_list<_Hp, __nat>, _Align> {
61 typedef __conditional_t<_Align == _Hp::value, typename _Hp::type, __fallback_overaligned<_Align> > type;
64 template <class _Hp, class _Tp, size_t _Align>
65 struct __find_pod<__type_list<_Hp, _Tp>, _Align> {
66 typedef __conditional_t<_Align == _Hp::value, typename _Hp::type, typename __find_pod<_Tp, _Align>::type> type;
69 template <class _TL, size_t _Len>
70 struct __find_max_align;
72 template <class _Hp, size_t _Len>
73 struct __find_max_align<__type_list<_Hp, __nat>, _Len> : public integral_constant<size_t, _Hp::value> {};
75 template <size_t _Len, size_t _A1, size_t _A2>
76 struct __select_align {
78 static const size_t __min = _A2 < _A1 ? _A2 : _A1;
79 static const size_t __max = _A1 < _A2 ? _A2 : _A1;
82 static const size_t value = _Len < __max ? __min : __max;
85 template <class _Hp, class _Tp, size_t _Len>
86 struct __find_max_align<__type_list<_Hp, _Tp>, _Len>
87 : public integral_constant<size_t, __select_align<_Len, _Hp::value, __find_max_align<_Tp, _Len>::value>::value> {};
89 template <size_t _Len, size_t _Align = __find_max_align<__all_types, _Len>::value>
90 struct _LIBCPP_DEPRECATED_IN_CXX23 _LIBCPP_TEMPLATE_VIS aligned_storage {
91 typedef typename __find_pod<__all_types, _Align>::type _Aligner;
94 unsigned char __data[(_Len + _Align - 1) / _Align * _Align];
98 #if _LIBCPP_STD_VER >= 14
100 _LIBCPP_SUPPRESS_DEPRECATED_PUSH
101 template <size_t _Len, size_t _Align = __find_max_align<__all_types, _Len>::value>
102 using aligned_storage_t _LIBCPP_DEPRECATED_IN_CXX23 = typename aligned_storage<_Len, _Align>::type;
103 _LIBCPP_SUPPRESS_DEPRECATED_POP
107 #define _CREATE_ALIGNED_STORAGE_SPECIALIZATION(n) \
108 template <size_t _Len> \
109 struct _LIBCPP_DEPRECATED_IN_CXX23 _LIBCPP_TEMPLATE_VIS aligned_storage<_Len, n> { \
110 struct _ALIGNAS(n) type { \
111 unsigned char __lx[(_Len + n - 1) / n * n]; \
115 _CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x1);
116 _CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x2);
117 _CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x4);
118 _CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x8);
119 _CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x10);
120 _CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x20);
121 _CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x40);
122 _CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x80);
123 _CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x100);
124 _CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x200);
125 _CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x400);
126 _CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x800);
127 _CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x1000);
128 _CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x2000);
129 // PE/COFF does not support alignment beyond 8192 (=0x2000)
130 #if !defined(_LIBCPP_OBJECT_FORMAT_COFF)
131 _CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x4000);
132 #endif // !defined(_LIBCPP_OBJECT_FORMAT_COFF)
134 #undef _CREATE_ALIGNED_STORAGE_SPECIALIZATION
136 _LIBCPP_END_NAMESPACE_STD
138 #endif // _LIBCPP___TYPE_TRAITS_ALIGNED_STORAGE_H