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_ALLOCATOR_H 11 #define _LIBCPP___MEMORY_ALLOCATOR_H 12 13 #include <__config> 14 #include <__cstddef/ptrdiff_t.h> 15 #include <__cstddef/size_t.h> 16 #include <__memory/addressof.h> 17 #include <__memory/allocate_at_least.h> 18 #include <__memory/allocator_traits.h> 19 #include <__new/allocate.h> 20 #include <__new/exceptions.h> 21 #include <__type_traits/is_const.h> 22 #include <__type_traits/is_constant_evaluated.h> 23 #include <__type_traits/is_same.h> 24 #include <__type_traits/is_void.h> 25 #include <__type_traits/is_volatile.h> 26 #include <__utility/forward.h> 27 28 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 29 # pragma GCC system_header 30 #endif 31 32 _LIBCPP_BEGIN_NAMESPACE_STD 33 34 template <class _Tp> 35 class allocator; 36 37 #if _LIBCPP_STD_VER <= 17 38 // These specializations shouldn't be marked _LIBCPP_DEPRECATED_IN_CXX17. 39 // Specializing allocator<void> is deprecated, but not using it. 40 template <> 41 class _LIBCPP_TEMPLATE_VIS allocator<void> { 42 public: 43 _LIBCPP_DEPRECATED_IN_CXX17 typedef void* pointer; 44 _LIBCPP_DEPRECATED_IN_CXX17 typedef const void* const_pointer; 45 _LIBCPP_DEPRECATED_IN_CXX17 typedef void value_type; 46 47 template <class _Up> 48 struct _LIBCPP_DEPRECATED_IN_CXX17 rebind { 49 typedef allocator<_Up> other; 50 }; 51 }; 52 #endif // _LIBCPP_STD_VER <= 17 53 54 // This class provides a non-trivial default constructor to the class that derives from it 55 // if the condition is satisfied. 56 // 57 // The second template parameter exists to allow giving a unique type to __non_trivial_if, 58 // which makes it possible to avoid breaking the ABI when making this a base class of an 59 // existing class. Without that, imagine we have classes D1 and D2, both of which used to 60 // have no base classes, but which now derive from __non_trivial_if. The layout of a class 61 // that inherits from both D1 and D2 will change because the two __non_trivial_if base 62 // classes are not allowed to share the same address. 63 // 64 // By making those __non_trivial_if base classes unique, we work around this problem and 65 // it is safe to start deriving from __non_trivial_if in existing classes. 66 template <bool _Cond, class _Unique> 67 struct __non_trivial_if {}; 68 69 template <class _Unique> 70 struct __non_trivial_if<true, _Unique> { 71 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR __non_trivial_if() _NOEXCEPT {} 72 }; 73 74 // allocator 75 // 76 // Note: For ABI compatibility between C++20 and previous standards, we make 77 // allocator<void> trivial in C++20. 78 79 template <class _Tp> 80 class _LIBCPP_TEMPLATE_VIS allocator : private __non_trivial_if<!is_void<_Tp>::value, allocator<_Tp> > { 81 static_assert(!is_const<_Tp>::value, "std::allocator does not support const types"); 82 static_assert(!is_volatile<_Tp>::value, "std::allocator does not support volatile types"); 83 84 public: 85 typedef size_t size_type; 86 typedef ptrdiff_t difference_type; 87 typedef _Tp value_type; 88 typedef true_type propagate_on_container_move_assignment; 89 #if _LIBCPP_STD_VER <= 23 || defined(_LIBCPP_ENABLE_CXX26_REMOVED_ALLOCATOR_MEMBERS) 90 _LIBCPP_DEPRECATED_IN_CXX23 typedef true_type is_always_equal; 91 #endif 92 93 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 allocator() _NOEXCEPT = default; 94 95 template <class _Up> 96 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 allocator(const allocator<_Up>&) _NOEXCEPT {} 97 98 [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 _Tp* allocate(size_t __n) { 99 static_assert(sizeof(_Tp) >= 0, "cannot allocate memory for an incomplete type"); 100 if (__n > allocator_traits<allocator>::max_size(*this)) 101 __throw_bad_array_new_length(); 102 if (__libcpp_is_constant_evaluated()) { 103 return static_cast<_Tp*>(::operator new(__n * sizeof(_Tp))); 104 } else { 105 return std::__libcpp_allocate<_Tp>(__element_count(__n)); 106 } 107 } 108 109 #if _LIBCPP_STD_VER >= 23 110 [[nodiscard]] _LIBCPP_HIDE_FROM_ABI constexpr allocation_result<_Tp*> allocate_at_least(size_t __n) { 111 static_assert(sizeof(_Tp) >= 0, "cannot allocate memory for an incomplete type"); 112 return {allocate(__n), __n}; 113 } 114 #endif 115 116 _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 void deallocate(_Tp* __p, size_t __n) _NOEXCEPT { 117 if (__libcpp_is_constant_evaluated()) { 118 ::operator delete(__p); 119 } else { 120 std::__libcpp_deallocate<_Tp>(__p, __element_count(__n)); 121 } 122 } 123 124 // C++20 Removed members 125 #if _LIBCPP_STD_VER <= 17 126 _LIBCPP_DEPRECATED_IN_CXX17 typedef _Tp* pointer; 127 _LIBCPP_DEPRECATED_IN_CXX17 typedef const _Tp* const_pointer; 128 _LIBCPP_DEPRECATED_IN_CXX17 typedef _Tp& reference; 129 _LIBCPP_DEPRECATED_IN_CXX17 typedef const _Tp& const_reference; 130 131 template <class _Up> 132 struct _LIBCPP_DEPRECATED_IN_CXX17 rebind { 133 typedef allocator<_Up> other; 134 }; 135 136 _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_HIDE_FROM_ABI pointer address(reference __x) const _NOEXCEPT { 137 return std::addressof(__x); 138 } 139 _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_HIDE_FROM_ABI const_pointer address(const_reference __x) const _NOEXCEPT { 140 return std::addressof(__x); 141 } 142 143 [[__nodiscard__]] _LIBCPP_HIDE_FROM_ABI _LIBCPP_DEPRECATED_IN_CXX17 _Tp* allocate(size_t __n, const void*) { 144 return allocate(__n); 145 } 146 147 _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_HIDE_FROM_ABI size_type max_size() const _NOEXCEPT { 148 return size_type(~0) / sizeof(_Tp); 149 } 150 151 template <class _Up, class... _Args> 152 _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_HIDE_FROM_ABI void construct(_Up* __p, _Args&&... __args) { 153 ::new ((void*)__p) _Up(std::forward<_Args>(__args)...); 154 } 155 156 _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_HIDE_FROM_ABI void destroy(pointer __p) { __p->~_Tp(); } 157 #endif 158 }; 159 160 template <class _Tp, class _Up> 161 inline _LIBCPP_HIDE_FROM_ABI _LIBCPP_CONSTEXPR_SINCE_CXX20 bool 162 operator==(const allocator<_Tp>&, const allocator<_Up>&) _NOEXCEPT { 163 return true; 164 } 165 166 #if _LIBCPP_STD_VER <= 17 167 168 template <class _Tp, class _Up> 169 inline _LIBCPP_HIDE_FROM_ABI bool operator!=(const allocator<_Tp>&, const allocator<_Up>&) _NOEXCEPT { 170 return false; 171 } 172 173 #endif 174 175 _LIBCPP_END_NAMESPACE_STD 176 177 #endif // _LIBCPP___MEMORY_ALLOCATOR_H 178