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> 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 typename conditional< 58 _Align == _Hp::value, 59 typename _Hp::type, 60 __fallback_overaligned<_Align> 61 >::type type; 62 }; 63 64 template <class _Hp, class _Tp, size_t _Align> 65 struct __find_pod<__type_list<_Hp, _Tp>, _Align> 66 { 67 typedef typename conditional< 68 _Align == _Hp::value, 69 typename _Hp::type, 70 typename __find_pod<_Tp, _Align>::type 71 >::type type; 72 }; 73 74 template <class _TL, size_t _Len> struct __find_max_align; 75 76 template <class _Hp, size_t _Len> 77 struct __find_max_align<__type_list<_Hp, __nat>, _Len> : public integral_constant<size_t, _Hp::value> {}; 78 79 template <size_t _Len, size_t _A1, size_t _A2> 80 struct __select_align 81 { 82 private: 83 static const size_t __min = _A2 < _A1 ? _A2 : _A1; 84 static const size_t __max = _A1 < _A2 ? _A2 : _A1; 85 public: 86 static const size_t value = _Len < __max ? __min : __max; 87 }; 88 89 template <class _Hp, class _Tp, size_t _Len> 90 struct __find_max_align<__type_list<_Hp, _Tp>, _Len> 91 : public integral_constant<size_t, __select_align<_Len, _Hp::value, __find_max_align<_Tp, _Len>::value>::value> {}; 92 93 template <size_t _Len, size_t _Align = __find_max_align<__all_types, _Len>::value> 94 struct _LIBCPP_TEMPLATE_VIS aligned_storage 95 { 96 typedef typename __find_pod<__all_types, _Align>::type _Aligner; 97 union type 98 { 99 _Aligner __align; 100 unsigned char __data[(_Len + _Align - 1)/_Align * _Align]; 101 }; 102 }; 103 104 #if _LIBCPP_STD_VER > 11 105 template <size_t _Len, size_t _Align = __find_max_align<__all_types, _Len>::value> 106 using aligned_storage_t = typename aligned_storage<_Len, _Align>::type; 107 #endif 108 109 #define _CREATE_ALIGNED_STORAGE_SPECIALIZATION(n) \ 110 template <size_t _Len>\ 111 struct _LIBCPP_TEMPLATE_VIS aligned_storage<_Len, n>\ 112 {\ 113 struct _ALIGNAS(n) type\ 114 {\ 115 unsigned char __lx[(_Len + n - 1)/n * n];\ 116 };\ 117 } 118 119 _CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x1); 120 _CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x2); 121 _CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x4); 122 _CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x8); 123 _CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x10); 124 _CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x20); 125 _CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x40); 126 _CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x80); 127 _CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x100); 128 _CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x200); 129 _CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x400); 130 _CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x800); 131 _CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x1000); 132 _CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x2000); 133 // PE/COFF does not support alignment beyond 8192 (=0x2000) 134 #if !defined(_LIBCPP_OBJECT_FORMAT_COFF) 135 _CREATE_ALIGNED_STORAGE_SPECIALIZATION(0x4000); 136 #endif // !defined(_LIBCPP_OBJECT_FORMAT_COFF) 137 138 #undef _CREATE_ALIGNED_STORAGE_SPECIALIZATION 139 140 _LIBCPP_END_NAMESPACE_STD 141 142 #endif // _LIBCPP___TYPE_TRAITS_ALIGNED_STORAGE_H 143