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 <__memory/allocator_traits.h> 15 #include <__utility/forward.h> 16 #include <cstddef> 17 #include <new> 18 #include <stdexcept> 19 #include <type_traits> 20 21 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER) 22 # pragma GCC system_header 23 #endif 24 25 _LIBCPP_BEGIN_NAMESPACE_STD 26 27 template <class _Tp> class allocator; 28 29 #if _LIBCPP_STD_VER <= 17 30 template <> 31 class _LIBCPP_TEMPLATE_VIS allocator<void> 32 { 33 public: 34 _LIBCPP_DEPRECATED_IN_CXX17 typedef void* pointer; 35 _LIBCPP_DEPRECATED_IN_CXX17 typedef const void* const_pointer; 36 _LIBCPP_DEPRECATED_IN_CXX17 typedef void value_type; 37 38 template <class _Up> struct _LIBCPP_DEPRECATED_IN_CXX17 rebind {typedef allocator<_Up> other;}; 39 }; 40 #endif 41 42 // This class provides a non-trivial default constructor to the class that derives from it 43 // if the condition is satisfied. 44 // 45 // The second template parameter exists to allow giving a unique type to __non_trivial_if, 46 // which makes it possible to avoid breaking the ABI when making this a base class of an 47 // existing class. Without that, imagine we have classes D1 and D2, both of which used to 48 // have no base classes, but which now derive from __non_trivial_if. The layout of a class 49 // that inherits from both D1 and D2 will change because the two __non_trivial_if base 50 // classes are not allowed to share the same address. 51 // 52 // By making those __non_trivial_if base classes unique, we work around this problem and 53 // it is safe to start deriving from __non_trivial_if in existing classes. 54 template <bool _Cond, class _Unique> 55 struct __non_trivial_if { }; 56 57 template <class _Unique> 58 struct __non_trivial_if<true, _Unique> { 59 _LIBCPP_INLINE_VISIBILITY 60 _LIBCPP_CONSTEXPR __non_trivial_if() _NOEXCEPT { } 61 }; 62 63 // allocator 64 // 65 // Note: For ABI compatibility between C++20 and previous standards, we make 66 // allocator<void> trivial in C++20. 67 68 template <class _Tp> 69 class _LIBCPP_TEMPLATE_VIS allocator 70 : private __non_trivial_if<!is_void<_Tp>::value, allocator<_Tp> > 71 { 72 static_assert(!is_const<_Tp>::value, "std::allocator does not support const types"); 73 static_assert(!is_volatile<_Tp>::value, "std::allocator does not support volatile types"); 74 public: 75 typedef size_t size_type; 76 typedef ptrdiff_t difference_type; 77 typedef _Tp value_type; 78 typedef true_type propagate_on_container_move_assignment; 79 typedef true_type is_always_equal; 80 81 _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 82 allocator() _NOEXCEPT = default; 83 84 template <class _Up> 85 _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 86 allocator(const allocator<_Up>&) _NOEXCEPT { } 87 88 _LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 89 _Tp* allocate(size_t __n) { 90 if (__n > allocator_traits<allocator>::max_size(*this)) 91 __throw_bad_array_new_length(); 92 if (__libcpp_is_constant_evaluated()) { 93 return static_cast<_Tp*>(::operator new(__n * sizeof(_Tp))); 94 } else { 95 return static_cast<_Tp*>(_VSTD::__libcpp_allocate(__n * sizeof(_Tp), _LIBCPP_ALIGNOF(_Tp))); 96 } 97 } 98 99 _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 100 void deallocate(_Tp* __p, size_t __n) _NOEXCEPT { 101 if (__libcpp_is_constant_evaluated()) { 102 ::operator delete(__p); 103 } else { 104 _VSTD::__libcpp_deallocate((void*)__p, __n * sizeof(_Tp), _LIBCPP_ALIGNOF(_Tp)); 105 } 106 } 107 108 // C++20 Removed members 109 #if _LIBCPP_STD_VER <= 17 || defined(_LIBCPP_ENABLE_CXX20_REMOVED_ALLOCATOR_MEMBERS) 110 _LIBCPP_DEPRECATED_IN_CXX17 typedef _Tp* pointer; 111 _LIBCPP_DEPRECATED_IN_CXX17 typedef const _Tp* const_pointer; 112 _LIBCPP_DEPRECATED_IN_CXX17 typedef _Tp& reference; 113 _LIBCPP_DEPRECATED_IN_CXX17 typedef const _Tp& const_reference; 114 115 template <class _Up> 116 struct _LIBCPP_DEPRECATED_IN_CXX17 rebind { 117 typedef allocator<_Up> other; 118 }; 119 120 _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_INLINE_VISIBILITY 121 pointer address(reference __x) const _NOEXCEPT { 122 return _VSTD::addressof(__x); 123 } 124 _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_INLINE_VISIBILITY 125 const_pointer address(const_reference __x) const _NOEXCEPT { 126 return _VSTD::addressof(__x); 127 } 128 129 _LIBCPP_NODISCARD_AFTER_CXX17 _LIBCPP_INLINE_VISIBILITY _LIBCPP_DEPRECATED_IN_CXX17 130 _Tp* allocate(size_t __n, const void*) { 131 return allocate(__n); 132 } 133 134 _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_INLINE_VISIBILITY size_type max_size() const _NOEXCEPT { 135 return size_type(~0) / sizeof(_Tp); 136 } 137 138 template <class _Up, class... _Args> 139 _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_INLINE_VISIBILITY 140 void construct(_Up* __p, _Args&&... __args) { 141 ::new ((void*)__p) _Up(_VSTD::forward<_Args>(__args)...); 142 } 143 144 _LIBCPP_DEPRECATED_IN_CXX17 _LIBCPP_INLINE_VISIBILITY 145 void destroy(pointer __p) { 146 __p->~_Tp(); 147 } 148 #endif 149 }; 150 151 template <class _Tp, class _Up> 152 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 153 bool operator==(const allocator<_Tp>&, const allocator<_Up>&) _NOEXCEPT {return true;} 154 155 template <class _Tp, class _Up> 156 inline _LIBCPP_INLINE_VISIBILITY _LIBCPP_CONSTEXPR_AFTER_CXX17 157 bool operator!=(const allocator<_Tp>&, const allocator<_Up>&) _NOEXCEPT {return false;} 158 159 _LIBCPP_END_NAMESPACE_STD 160 161 #endif // _LIBCPP___MEMORY_ALLOCATOR_H 162