libstdc++
memory
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1// <memory> -*- C++ -*-
2
3// Copyright (C) 2001-2020 Free Software Foundation, Inc.
4//
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)
9// any later version.
10
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.
15
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.
19
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/>.
24
25/*
26 * Copyright (c) 1997-1999
27 * Silicon Graphics Computer Systems, Inc.
28 *
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.
36 *
37 */
38
39/** @file include/memory
40 * This is a Standard C++ Library header.
41 * @ingroup memory
42 */
43
44#ifndef _GLIBCXX_MEMORY
45#define _GLIBCXX_MEMORY 1
46
47#pragma GCC system_header
48
49/**
50 * @defgroup memory Memory
51 * @ingroup utilities
52 *
53 * Components for memory allocation, deallocation, and management.
54 */
55
56/**
57 * @defgroup pointer_abstractions Pointer Abstractions
58 * @ingroup memory
59 *
60 * Smart pointers, etc.
61 */
62
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>
69#include <bits/ranges_uninitialized.h>
70
71#if __cplusplus >= 201103L
72# include <exception> // std::exception
73# include <typeinfo> // std::type_info in get_deleter
74# include <iosfwd> // std::basic_ostream
75# include <ext/atomicity.h>
76# include <ext/concurrence.h>
77# include <bits/functexcept.h>
78# include <bits/stl_function.h> // std::less
79# include <bits/uses_allocator.h>
80# include <bits/alloc_traits.h>
81# include <type_traits>
82# include <debug/debug.h>
83# include <bits/unique_ptr.h>
84# include <bits/shared_ptr.h>
85# include <bits/shared_ptr_atomic.h>
86# if _GLIBCXX_USE_DEPRECATED
87# include <backward/auto_ptr.h>
88# endif
89#else
90# include <backward/auto_ptr.h>
91#endif
92
93#if __cplusplus >= 201103L
94#include <cstdint>
95#if __cplusplus > 201703L
96# include <bit> // for has_single_bit
97# include <new> // for placement operator new
98# include <tuple> // for tuple, make_tuple, make_from_tuple
99#endif
100namespace std _GLIBCXX_VISIBILITY(default)
101{
102_GLIBCXX_BEGIN_NAMESPACE_VERSION
103
104/**
105 * @brief Fit aligned storage in buffer.
106 * @ingroup memory
107 *
108 * This function tries to fit @a __size bytes of storage with alignment
109 * @a __align into the buffer @a __ptr of size @a __space bytes. If such
110 * a buffer fits then @a __ptr is changed to point to the first byte of the
111 * aligned storage and @a __space is reduced by the bytes used for alignment.
112 *
113 * C++11 20.6.5 [ptr.align]
114 *
115 * @param __align A fundamental or extended alignment value.
116 * @param __size Size of the aligned storage required.
117 * @param __ptr Pointer to a buffer of @a __space bytes.
118 * @param __space Size of the buffer pointed to by @a __ptr.
119 * @return the updated pointer if the aligned storage fits, otherwise nullptr.
120 *
121 */
122inline void*
123align(size_t __align, size_t __size, void*& __ptr, size_t& __space) noexcept
124{
125#ifdef _GLIBCXX_USE_C99_STDINT_TR1
126 const auto __intptr = reinterpret_cast<uintptr_t>(__ptr);
127#else
128 // Cannot use std::uintptr_t so assume that std::size_t can be used instead.
129 static_assert(sizeof(size_t) >= sizeof(void*),
130 "std::size_t must be a suitable substitute for std::uintptr_t");
131 const auto __intptr = reinterpret_cast<unsigned long long>(__ptr);
132#endif
133 const auto __aligned = (__intptr - 1u + __align) & -__align;
134 const auto __diff = __aligned - __intptr;
135 if ((__size + __diff) > __space)
136 return nullptr;
137 else
138 {
139 __space -= __diff;
140 return __ptr = reinterpret_cast<void*>(__aligned);
141 }
142}
143
144/** @defgroup ptr_safety Pointer Safety and Garbage Collection
145 * @ingroup memory
146 *
147 * Utilities to assist with garbage collection in an implementation
148 * that supports <em>strict pointer safety</em>.
149 * This implementation only supports <em>relaxed pointer safety</em>
150 * and so these functions have no effect.
151 *
152 * C++11 20.6.4 [util.dynamic.safety], Pointer safety
153 *
154 * @{
155 */
156
157/// Constants representing the different types of pointer safety.
158enum class pointer_safety { relaxed, preferred, strict };
159
160/// Inform a garbage collector that an object is still in use.
161inline void
162declare_reachable(void*) { }
163
164/// Unregister an object previously registered with declare_reachable.
165template <typename _Tp>
166 inline _Tp*
167 undeclare_reachable(_Tp* __p) { return __p; }
168
169/// Inform a garbage collector that a region of memory need not be traced.
170inline void
171declare_no_pointers(char*, size_t) { }
172
173/// Unregister a range previously registered with declare_no_pointers.
174inline void
175undeclare_no_pointers(char*, size_t) { }
176
177/// The type of pointer safety supported by the implementation.
178inline pointer_safety
179get_pointer_safety() noexcept { return pointer_safety::relaxed; }
180/// @}
181
182#if __cplusplus > 201703L
183#define __cpp_lib_assume_aligned 201811L
184 /** @brief Inform the compiler that a pointer is aligned.
185 *
186 * @tparam _Align An alignment value (i.e. a power of two)
187 * @tparam _Tp An object type
188 * @param __ptr A pointer that is aligned to _Align
189 *
190 * C++20 20.10.6 [ptr.align]
191 *
192 * @ingroup memory
193 */
194 template<size_t _Align, class _Tp>
195 [[nodiscard,__gnu__::__always_inline__]]
196 constexpr _Tp*
197 assume_aligned(_Tp* __ptr) noexcept
198 {
199 static_assert(std::has_single_bit(_Align));
200 if (std::is_constant_evaluated())
201 return __ptr;
202 else
203 {
204 // This function is expected to be used in hot code, where
205 // __glibcxx_assert would add unwanted overhead.
206 _GLIBCXX_DEBUG_ASSERT((std::uintptr_t)__ptr % _Align == 0);
207 return static_cast<_Tp*>(__builtin_assume_aligned(__ptr, _Align));
208 }
209 }
210#endif // C++2a
211
212#if __cplusplus > 201703L
213 template<typename _Tp>
214 struct __is_pair : false_type { };
215 template<typename _Tp, typename _Up>
216 struct __is_pair<pair<_Tp, _Up>> : true_type { };
217 template<typename _Tp, typename _Up>
218 struct __is_pair<const pair<_Tp, _Up>> : true_type { };
219
220/** @addtogroup allocators
221 * @{
222 */
223 template<typename _Tp, typename __ = _Require<__not_<__is_pair<_Tp>>>,
224 typename _Alloc, typename... _Args>
225 constexpr auto
226 __uses_alloc_args(const _Alloc& __a, _Args&&... __args) noexcept
227 {
228 if constexpr (uses_allocator_v<remove_cv_t<_Tp>, _Alloc>)
229 {
230 if constexpr (is_constructible_v<_Tp, allocator_arg_t,
231 const _Alloc&, _Args...>)
232 {
233 return tuple<allocator_arg_t, const _Alloc&, _Args&&...>(
234 allocator_arg, __a, std::forward<_Args>(__args)...);
235 }
236 else
237 {
238 static_assert(is_constructible_v<_Tp, _Args..., const _Alloc&>,
239 "construction with an allocator must be possible"
240 " if uses_allocator is true");
241
242 return tuple<_Args&&..., const _Alloc&>(
243 std::forward<_Args>(__args)..., __a);
244 }
245 }
246 else
247 {
248 static_assert(is_constructible_v<_Tp, _Args...>);
249
250 return tuple<_Args&&...>(std::forward<_Args>(__args)...);
251 }
252 }
253
254#if __cpp_concepts
255 template<typename _Tp>
256 concept _Std_pair = __is_pair<_Tp>::value;
257#endif
258
259// This is a temporary workaround until -fconcepts is implied by -std=gnu++2a
260#if __cpp_concepts
261# define _GLIBCXX_STD_PAIR_CONSTRAINT(T) _Std_pair T
262# define _GLIBCXX_STD_PAIR_CONSTRAINT_(T) _Std_pair T
263#else
264# define _GLIBCXX_STD_PAIR_CONSTRAINT(T) \
265 typename T, typename __ = _Require<__is_pair<T>>
266# define _GLIBCXX_STD_PAIR_CONSTRAINT_(T) typename T, typename
267#endif
268
269 template<typename _Tp,
270#if ! __cpp_concepts
271 typename __ = _Require<__not_<__is_pair<_Tp>>>,
272#endif
273 typename _Alloc, typename... _Args>
274 constexpr auto
275 uses_allocator_construction_args(const _Alloc& __a,
276 _Args&&... __args) noexcept
277#if __cpp_concepts
278 requires (! _Std_pair<_Tp>)
279#endif
280 {
281 return std::__uses_alloc_args<_Tp>(__a, std::forward<_Args>(__args)...);
282 }
283
284 template<_GLIBCXX_STD_PAIR_CONSTRAINT(_Tp), typename _Alloc,
285 typename _Tuple1, typename _Tuple2>
286 constexpr auto
287 uses_allocator_construction_args(const _Alloc& __a, piecewise_construct_t,
288 _Tuple1&& __x, _Tuple2&& __y) noexcept;
289
290 template<_GLIBCXX_STD_PAIR_CONSTRAINT(_Tp), typename _Alloc>
291 constexpr auto
292 uses_allocator_construction_args(const _Alloc&) noexcept;
293
294 template<_GLIBCXX_STD_PAIR_CONSTRAINT(_Tp), typename _Alloc,
295 typename _Up, typename _Vp>
296 constexpr auto
297 uses_allocator_construction_args(const _Alloc&, _Up&&, _Vp&&) noexcept;
298
299 template<_GLIBCXX_STD_PAIR_CONSTRAINT(_Tp), typename _Alloc,
300 typename _Up, typename _Vp>
301 constexpr auto
302 uses_allocator_construction_args(const _Alloc&,
303 const pair<_Up, _Vp>&) noexcept;
304
305 template<_GLIBCXX_STD_PAIR_CONSTRAINT(_Tp), typename _Alloc,
306 typename _Up, typename _Vp>
307 constexpr auto
308 uses_allocator_construction_args(const _Alloc&, pair<_Up, _Vp>&&) noexcept;
309
310 template<_GLIBCXX_STD_PAIR_CONSTRAINT_(_Tp), typename _Alloc,
311 typename _Tuple1, typename _Tuple2>
312 constexpr auto
313 uses_allocator_construction_args(const _Alloc& __a, piecewise_construct_t,
314 _Tuple1&& __x, _Tuple2&& __y) noexcept
315 {
316 using _Tp1 = typename _Tp::first_type;
317 using _Tp2 = typename _Tp::second_type;
318
319 return std::make_tuple(piecewise_construct,
320 std::apply([&__a](auto&&... __args1) {
321 return std::uses_allocator_construction_args<_Tp1>(
322 __a, std::forward<decltype(__args1)>(__args1)...);
323 }, std::forward<_Tuple1>(__x)),
324 std::apply([&__a](auto&&... __args2) {
325 return std::uses_allocator_construction_args<_Tp2>(
326 __a, std::forward<decltype(__args2)>(__args2)...);
327 }, std::forward<_Tuple2>(__y)));
328 }
329
330 template<_GLIBCXX_STD_PAIR_CONSTRAINT_(_Tp), typename _Alloc>
331 constexpr auto
332 uses_allocator_construction_args(const _Alloc& __a) noexcept
333 {
334 using _Tp1 = typename _Tp::first_type;
335 using _Tp2 = typename _Tp::second_type;
336
337 return std::make_tuple(piecewise_construct,
338 std::uses_allocator_construction_args<_Tp1>(__a),
339 std::uses_allocator_construction_args<_Tp2>(__a));
340 }
341
342 template<_GLIBCXX_STD_PAIR_CONSTRAINT_(_Tp), typename _Alloc,
343 typename _Up, typename _Vp>
344 constexpr auto
345 uses_allocator_construction_args(const _Alloc& __a, _Up&& __u, _Vp&& __v)
346 noexcept
347 {
348 using _Tp1 = typename _Tp::first_type;
349 using _Tp2 = typename _Tp::second_type;
350
351 return std::make_tuple(piecewise_construct,
352 std::uses_allocator_construction_args<_Tp1>(__a,
353 std::forward<_Up>(__u)),
354 std::uses_allocator_construction_args<_Tp2>(__a,
355 std::forward<_Vp>(__v)));
356 }
357
358 template<_GLIBCXX_STD_PAIR_CONSTRAINT_(_Tp), typename _Alloc,
359 typename _Up, typename _Vp>
360 constexpr auto
361 uses_allocator_construction_args(const _Alloc& __a,
362 const pair<_Up, _Vp>& __pr) noexcept
363 {
364 using _Tp1 = typename _Tp::first_type;
365 using _Tp2 = typename _Tp::second_type;
366
367 return std::make_tuple(piecewise_construct,
368 std::uses_allocator_construction_args<_Tp1>(__a, __pr.first),
369 std::uses_allocator_construction_args<_Tp2>(__a, __pr.second));
370 }
371
372 template<_GLIBCXX_STD_PAIR_CONSTRAINT_(_Tp), typename _Alloc,
373 typename _Up, typename _Vp>
374 constexpr auto
375 uses_allocator_construction_args(const _Alloc& __a,
376 pair<_Up, _Vp>&& __pr) noexcept
377 {
378 using _Tp1 = typename _Tp::first_type;
379 using _Tp2 = typename _Tp::second_type;
380
381 // _GLIBCXX_RESOLVE_LIB_DEFECTS
382 // 3527. uses_allocator_construction_args handles rvalue pairs
383 // of rvalue references incorrectly
384 return std::make_tuple(piecewise_construct,
385 std::uses_allocator_construction_args<_Tp1>(__a,
386 std::get<0>(std::move(__pr))),
387 std::uses_allocator_construction_args<_Tp2>(__a,
388 std::get<1>(std::move(__pr))));
389 }
390
391 template<typename _Tp, typename _Alloc, typename... _Args>
392 inline _Tp
393 make_obj_using_allocator(const _Alloc& __a, _Args&&... __args)
394 {
395 return std::make_from_tuple<_Tp>(
396 std::uses_allocator_construction_args<_Tp>(__a,
397 std::forward<_Args>(__args)...));
398 }
399
400 template<typename _Tp, typename _Alloc, typename... _Args>
401 inline _Tp*
402 uninitialized_construct_using_allocator(_Tp* __p, const _Alloc& __a,
403 _Args&&... __args)
404 {
405 return std::apply([&](auto&&... __xs) {
406 return std::construct_at(__p, std::forward<decltype(__xs)>(__xs)...);
407 }, std::uses_allocator_construction_args<_Tp>(__a,
408 std::forward<_Args>(__args)...));
409 }
410// @}
411
412#endif // C++2a
413
414_GLIBCXX_END_NAMESPACE_VERSION
415} // namespace
416#endif // C++11
417
418#if __cplusplus > 201402L
419// Parallel STL algorithms
420# if _PSTL_EXECUTION_POLICIES_DEFINED
421// If <execution> has already been included, pull in implementations
422# include <pstl/glue_memory_impl.h>
423# else
424// Otherwise just pull in forward declarations
425# include <pstl/glue_memory_defs.h>
426# endif
427
428// Feature test macro for parallel algorithms
429# define __cpp_lib_parallel_algorithm 201603L
430#endif // C++17
431
432#endif /* _GLIBCXX_MEMORY */