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___TYPE_TRAITS_ALIGNED_STORAGE_H
10 #define _LIBCPP___TYPE_TRAITS_ALIGNED_STORAGE_H
11
12 #include <__config>
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>
17 #include <cstddef>
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 struct __align_type
27 {
28 static const size_t value = _LIBCPP_PREFERRED_ALIGNOF(_Tp);
29 typedef _Tp type;
30 };
31
32 struct __struct_double {long double __lx;};
33 struct __struct_double4 {double __lx[4];};
34
35 typedef
36 __type_list<__align_type<unsigned char>,
37 __type_list<__align_type<unsigned short>,
38 __type_list<__align_type<unsigned int>,
39 __type_list<__align_type<unsigned long>,
40 __type_list<__align_type<unsigned long long>,
41 __type_list<__align_type<double>,
42 __type_list<__align_type<long double>,
43 __type_list<__align_type<__struct_double>,
44 __type_list<__align_type<__struct_double4>,
45 __type_list<__align_type<int*>,
46 __nat
47 > > > > > > > > > > __all_types;
48
49 template <size_t _Align>
_ALIGNAS(_Align)50 struct _ALIGNAS(_Align) __fallback_overaligned {};
51
52 template <class _TL, size_t _Align> struct __find_pod;
53
54 template <class _Hp, size_t _Align>
55 struct __find_pod<__type_list<_Hp, __nat>, _Align>
56 {
57 typedef __conditional_t<_Align == _Hp::value, typename _Hp::type, __fallback_overaligned<_Align> > type;
58 };
59
60 template <class _Hp, class _Tp, size_t _Align>
61 struct __find_pod<__type_list<_Hp, _Tp>, _Align>
62 {
63 typedef __conditional_t<_Align == _Hp::value, typename _Hp::type, typename __find_pod<_Tp, _Align>::type> type;
64 };
65
66 template <class _TL, size_t _Len> struct __find_max_align;
67
68 template <class _Hp, size_t _Len>
69 struct __find_max_align<__type_list<_Hp, __nat>, _Len> : public integral_constant<size_t, _Hp::value> {};
70
71 template <size_t _Len, size_t _A1, size_t _A2>
72 struct __select_align
73 {
74 private:
75 static const size_t __min = _A2 < _A1 ? _A2 : _A1;
76 static const size_t __max = _A1 < _A2 ? _A2 : _A1;
77 public:
78 static const size_t value = _Len < __max ? __min : __max;
79 };
80
81 template <class _Hp, class _Tp, size_t _Len>
82 struct __find_max_align<__type_list<_Hp, _Tp>, _Len>
83 : public integral_constant<size_t, __select_align<_Len, _Hp::value, __find_max_align<_Tp, _Len>::value>::value> {};
84
85 template <size_t _Len, size_t _Align = __find_max_align<__all_types, _Len>::value>
86 struct _LIBCPP_DEPRECATED_IN_CXX23 _LIBCPP_TEMPLATE_VIS aligned_storage
87 {
88 typedef typename __find_pod<__all_types, _Align>::type _Aligner;
89 union type
90 {
91 _Aligner __align;
92 unsigned char __data[(_Len + _Align - 1)/_Align * _Align];
93 };
94 };
95
96 #if _LIBCPP_STD_VER >= 14
97
98 _LIBCPP_SUPPRESS_DEPRECATED_PUSH
99 template <size_t _Len, size_t _Align = __find_max_align<__all_types, _Len>::value>
100 using aligned_storage_t _LIBCPP_DEPRECATED_IN_CXX23 = typename aligned_storage<_Len, _Align>::type;
101 _LIBCPP_SUPPRESS_DEPRECATED_POP
102
103 #endif
104
105 #define _CREATE_ALIGNED_STORAGE_SPECIALIZATION(n) \
106 template <size_t _Len> \
107 struct _LIBCPP_DEPRECATED_IN_CXX23 _LIBCPP_TEMPLATE_VIS aligned_storage<_Len, n> { \
108 struct _ALIGNAS(n) type { \
109 unsigned char __lx[(_Len + n - 1) / n * n]; \
110 }; \
111 }
112
113 _CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x1);
114 _CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x2);
115 _CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x4);
116 _CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x8);
117 _CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x10);
118 _CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x20);
119 _CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x40);
120 _CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x80);
121 _CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x100);
122 _CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x200);
123 _CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x400);
124 _CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x800);
125 _CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x1000);
126 _CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x2000);
127 // PE/COFF does not support alignment beyond 8192 (=0x2000)
128 #if !defined(_LIBCPP_OBJECT_FORMAT_COFF)
129 _CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x4000);
130 #endif // !defined(_LIBCPP_OBJECT_FORMAT_COFF)
131
132 #undef _CREATE_ALIGNED_STORAGE_SPECIALIZATION
133
134 _LIBCPP_END_NAMESPACE_STD
135
136 #endif // _LIBCPP___TYPE_TRAITS_ALIGNED_STORAGE_H
137