1 // <memory> -*- C++ -*-
3 // Copyright (C) 2001-2020 Free Software Foundation, Inc.
5 // This file is part of the GNU ISO C++ Library. This library is free
6 // software; you can redistribute it and/or modify it under the
7 // terms of the GNU General Public License as published by the
8 // Free Software Foundation; either version 3, or (at your option)
11 // This library is distributed in the hope that it will be useful,
12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 // GNU General Public License for more details.
16 // Under Section 7 of GPL version 3, you are granted additional
17 // permissions described in the GCC Runtime Library Exception, version
18 // 3.1, as published by the Free Software Foundation.
20 // You should have received a copy of the GNU General Public License and
21 // a copy of the GCC Runtime Library Exception along with this program;
22 // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
23 // <http://www.gnu.org/licenses/>.
26 * Copyright (c) 1997-1999
27 * Silicon Graphics Computer Systems, Inc.
29 * Permission to use, copy, modify, distribute and sell this software
30 * and its documentation for any purpose is hereby granted without fee,
31 * provided that the above copyright notice appear in all copies and
32 * that both that copyright notice and this permission notice appear
33 * in supporting documentation. Silicon Graphics makes no
34 * representations about the suitability of this software for any
35 * purpose. It is provided "as is" without express or implied warranty.
39 /** @file include/memory
40 * This is a Standard C++ Library header.
44 #ifndef _GLIBCXX_MEMORY
45 #define _GLIBCXX_MEMORY 1
47 #pragma GCC system_header
50 * @defgroup memory Memory
53 * Components for memory allocation, deallocation, and management.
57 * @defgroup pointer_abstractions Pointer Abstractions
60 * Smart pointers, etc.
63 #include <bits/stl_algobase.h>
64 #include <bits/allocator.h>
65 #include <bits/stl_construct.h>
66 #include <bits/stl_uninitialized.h>
67 #include <bits/stl_tempbuf.h>
68 #include <bits/stl_raw_storage_iter.h>
70 #if __cplusplus >= 201103L
71 # include <exception> // std::exception
72 # include <typeinfo> // std::type_info in get_deleter
73 # include <iosfwd> // std::basic_ostream
74 # include <ext/atomicity.h>
75 # include <ext/concurrence.h>
76 # include <bits/functexcept.h>
77 # include <bits/stl_function.h> // std::less
78 # include <bits/uses_allocator.h>
79 # include <bits/alloc_traits.h>
80 # include <type_traits>
81 # include <debug/debug.h>
82 # include <bits/unique_ptr.h>
83 # include <bits/shared_ptr.h>
84 # include <bits/shared_ptr_atomic.h>
85 # if _GLIBCXX_USE_DEPRECATED
86 # include <backward/auto_ptr.h>
89 # include <backward/auto_ptr.h>
92 #if __cplusplus >= 201103L
94 #if __cplusplus > 201703L
95 # include <bit> // for ispow2
96 # include <new> // for placement operator new
97 # include <tuple> // for tuple, make_tuple, make_from_tuple
99 namespace std _GLIBCXX_VISIBILITY(default)
101 _GLIBCXX_BEGIN_NAMESPACE_VERSION
104 * @brief Fit aligned storage in buffer.
107 * This function tries to fit @a __size bytes of storage with alignment
108 * @a __align into the buffer @a __ptr of size @a __space bytes. If such
109 * a buffer fits then @a __ptr is changed to point to the first byte of the
110 * aligned storage and @a __space is reduced by the bytes used for alignment.
112 * C++11 20.6.5 [ptr.align]
114 * @param __align A fundamental or extended alignment value.
115 * @param __size Size of the aligned storage required.
116 * @param __ptr Pointer to a buffer of @a __space bytes.
117 * @param __space Size of the buffer pointed to by @a __ptr.
118 * @return the updated pointer if the aligned storage fits, otherwise nullptr.
122 align(size_t __align, size_t __size, void*& __ptr, size_t& __space) noexcept
124 #ifdef _GLIBCXX_USE_C99_STDINT_TR1
125 const auto __intptr = reinterpret_cast<uintptr_t>(__ptr);
127 // Cannot use std::uintptr_t so assume that std::size_t can be used instead.
128 static_assert(sizeof(size_t) >= sizeof(void*),
129 "std::size_t must be a suitable substitute for std::uintptr_t");
130 const auto __intptr = reinterpret_cast<unsigned long long>(__ptr);
132 const auto __aligned = (__intptr - 1u + __align) & -__align;
133 const auto __diff = __aligned - __intptr;
134 if ((__size + __diff) > __space)
139 return __ptr = reinterpret_cast<void*>(__aligned);
143 /** @defgroup ptr_safety Pointer Safety and Garbage Collection
146 * Utilities to assist with garbage collection in an implementation
147 * that supports <em>strict pointer safety</em>.
148 * This implementation only supports <em>relaxed pointer safety</em>
149 * and so these functions have no effect.
151 * C++11 20.6.4 [util.dynamic.safety], Pointer safety
156 /// Constants representing the different types of pointer safety.
157 enum class pointer_safety { relaxed, preferred, strict };
159 /// Inform a garbage collector that an object is still in use.
161 declare_reachable(void*) { }
163 /// Unregister an object previously registered with declare_reachable.
164 template <typename _Tp>
166 undeclare_reachable(_Tp* __p) { return __p; }
168 /// Inform a garbage collector that a region of memory need not be traced.
170 declare_no_pointers(char*, size_t) { }
172 /// Unregister a range previously registered with declare_no_pointers.
174 undeclare_no_pointers(char*, size_t) { }
176 /// The type of pointer safety supported by the implementation.
177 inline pointer_safety
178 get_pointer_safety() noexcept { return pointer_safety::relaxed; }
181 #if __cplusplus > 201703L
182 /** @brief Inform the compiler that a pointer is aligned.
184 * @tparam _Align An alignment value (i.e. a power of two)
185 * @tparam _Tp An object type
186 * @param __ptr A pointer that is aligned to _Align
189 template<size_t _Align, class _Tp>
190 [[nodiscard,__gnu__::__always_inline__]]
191 constexpr _Tp* assume_aligned(_Tp* __ptr)
193 static_assert(std::ispow2(_Align));
194 _GLIBCXX_DEBUG_ASSERT((std::uintptr_t)__ptr % _Align == 0);
195 return static_cast<_Tp*>(__builtin_assume_aligned(__ptr, _Align));
199 #if __cplusplus > 201703L
200 template<typename _Tp>
201 struct __is_pair : false_type { };
202 template<typename _Tp, typename _Up>
203 struct __is_pair<pair<_Tp, _Up>> : true_type { };
204 template<typename _Tp, typename _Up>
205 struct __is_pair<const pair<_Tp, _Up>> : true_type { };
207 /** @addtogroup allocators
210 template<typename _Tp, typename __ = _Require<__not_<__is_pair<_Tp>>>,
211 typename _Alloc, typename... _Args>
213 __uses_alloc_args(const _Alloc& __a, _Args&&... __args) noexcept
215 if constexpr (uses_allocator_v<remove_cv_t<_Tp>, _Alloc>)
217 if constexpr (is_constructible_v<_Tp, allocator_arg_t,
218 const _Alloc&, _Args...>)
220 return tuple<allocator_arg_t, const _Alloc&, _Args&&...>(
221 allocator_arg, __a, std::forward<_Args>(__args)...);
225 static_assert(is_constructible_v<_Tp, _Args..., const _Alloc&>,
226 "construction with an allocator must be possible"
227 " if uses_allocator is true");
229 return tuple<_Args&&..., const _Alloc&>(
230 std::forward<_Args>(__args)..., __a);
235 static_assert(is_constructible_v<_Tp, _Args...>);
237 return tuple<_Args&&...>(std::forward<_Args>(__args)...);
242 template<typename _Tp>
243 concept _Std_pair = __is_pair<_Tp>::value;
246 // This is a temporary workaround until -fconcepts is implied by -std=gnu++2a
248 # define _GLIBCXX_STD_PAIR_CONSTRAINT(T) _Std_pair T
249 # define _GLIBCXX_STD_PAIR_CONSTRAINT_(T) _Std_pair T
251 # define _GLIBCXX_STD_PAIR_CONSTRAINT(T) \
252 typename T, typename __ = _Require<__is_pair<T>>
253 # define _GLIBCXX_STD_PAIR_CONSTRAINT_(T) typename T, typename
256 template<typename _Tp,
258 typename __ = _Require<__not_<__is_pair<_Tp>>>,
260 typename _Alloc, typename... _Args>
262 uses_allocator_construction_args(const _Alloc& __a,
263 _Args&&... __args) noexcept
265 requires (! _Std_pair<_Tp>)
268 return std::__uses_alloc_args<_Tp>(__a, std::forward<_Args>(__args)...);
271 template<_GLIBCXX_STD_PAIR_CONSTRAINT(_Tp), typename _Alloc,
272 typename _Tuple1, typename _Tuple2>
274 uses_allocator_construction_args(const _Alloc& __a, piecewise_construct_t,
275 _Tuple1&& __x, _Tuple2&& __y) noexcept;
277 template<_GLIBCXX_STD_PAIR_CONSTRAINT(_Tp), typename _Alloc>
279 uses_allocator_construction_args(const _Alloc&) noexcept;
281 template<_GLIBCXX_STD_PAIR_CONSTRAINT(_Tp), typename _Alloc,
282 typename _Up, typename _Vp>
284 uses_allocator_construction_args(const _Alloc&, _Up&&, _Vp&&) noexcept;
286 template<_GLIBCXX_STD_PAIR_CONSTRAINT(_Tp), typename _Alloc,
287 typename _Up, typename _Vp>
289 uses_allocator_construction_args(const _Alloc&,
290 const pair<_Up, _Vp>&) noexcept;
292 template<_GLIBCXX_STD_PAIR_CONSTRAINT(_Tp), typename _Alloc,
293 typename _Up, typename _Vp>
295 uses_allocator_construction_args(const _Alloc&, pair<_Up, _Vp>&&) noexcept;
297 template<_GLIBCXX_STD_PAIR_CONSTRAINT_(_Tp), typename _Alloc,
298 typename _Tuple1, typename _Tuple2>
300 uses_allocator_construction_args(const _Alloc& __a, piecewise_construct_t,
301 _Tuple1&& __x, _Tuple2&& __y) noexcept
303 using _Tp1 = typename _Tp::first_type;
304 using _Tp2 = typename _Tp::second_type;
306 return std::make_tuple(piecewise_construct,
307 std::apply([&__a](auto&&... __args1) {
308 return std::uses_allocator_construction_args<_Tp1>(
309 __a, std::forward<decltype(__args1)>(__args1)...);
310 }, std::forward<_Tuple1>(__x)),
311 std::apply([&__a](auto&&... __args2) {
312 return std::uses_allocator_construction_args<_Tp2>(
313 __a, std::forward<decltype(__args2)>(__args2)...);
314 }, std::forward<_Tuple2>(__y)));
317 template<_GLIBCXX_STD_PAIR_CONSTRAINT_(_Tp), typename _Alloc>
319 uses_allocator_construction_args(const _Alloc& __a) noexcept
321 using _Tp1 = typename _Tp::first_type;
322 using _Tp2 = typename _Tp::second_type;
324 return std::make_tuple(piecewise_construct,
325 std::uses_allocator_construction_args<_Tp1>(__a),
326 std::uses_allocator_construction_args<_Tp2>(__a));
329 template<_GLIBCXX_STD_PAIR_CONSTRAINT_(_Tp), typename _Alloc,
330 typename _Up, typename _Vp>
332 uses_allocator_construction_args(const _Alloc& __a, _Up&& __u, _Vp&& __v)
335 using _Tp1 = typename _Tp::first_type;
336 using _Tp2 = typename _Tp::second_type;
338 return std::make_tuple(piecewise_construct,
339 std::uses_allocator_construction_args<_Tp1>(__a,
340 std::forward<_Up>(__u)),
341 std::uses_allocator_construction_args<_Tp2>(__a,
342 std::forward<_Vp>(__v)));
345 template<_GLIBCXX_STD_PAIR_CONSTRAINT_(_Tp), typename _Alloc,
346 typename _Up, typename _Vp>
348 uses_allocator_construction_args(const _Alloc& __a,
349 const pair<_Up, _Vp>& __pr) noexcept
351 using _Tp1 = typename _Tp::first_type;
352 using _Tp2 = typename _Tp::second_type;
354 return std::make_tuple(piecewise_construct,
355 std::uses_allocator_construction_args<_Tp1>(__a, __pr.first),
356 std::uses_allocator_construction_args<_Tp2>(__a, __pr.second));
359 template<_GLIBCXX_STD_PAIR_CONSTRAINT_(_Tp), typename _Alloc,
360 typename _Up, typename _Vp>
362 uses_allocator_construction_args(const _Alloc& __a,
363 pair<_Up, _Vp>&& __pr) noexcept
365 using _Tp1 = typename _Tp::first_type;
366 using _Tp2 = typename _Tp::second_type;
368 return std::make_tuple(piecewise_construct,
369 std::uses_allocator_construction_args<_Tp1>(__a,
370 std::move(__pr).first),
371 std::uses_allocator_construction_args<_Tp2>(__a,
372 std::move(__pr).second));
375 template<typename _Tp, typename _Alloc, typename... _Args>
377 make_obj_using_allocator(const _Alloc& __a, _Args&&... __args)
379 return std::make_from_tuple<_Tp>(
380 std::uses_allocator_construction_args<_Tp>(__a,
381 std::forward<_Args>(__args)...));
384 template<typename _Tp, typename _Alloc, typename... _Args>
386 uninitialized_construct_using_allocator(_Tp* __p, const _Alloc& __a,
389 void* __vp = const_cast<void*>(static_cast<const volatile void*>(__p));
390 return ::new(__vp) _Tp(std::make_obj_using_allocator<_Tp>(__a,
391 std::forward<_Args>(__args)...));
397 _GLIBCXX_END_NAMESPACE_VERSION
401 #if __cplusplus > 201402L
402 // Parallel STL algorithms
403 # if _PSTL_EXECUTION_POLICIES_DEFINED
404 // If <execution> has already been included, pull in implementations
405 # include <pstl/glue_memory_impl.h>
407 // Otherwise just pull in forward declarations
408 # include <pstl/glue_memory_defs.h>
411 // Feature test macro for parallel algorithms
412 # define __cpp_lib_parallel_algorithm 201603L
415 #endif /* _GLIBCXX_MEMORY */