libstdc++
new
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1// The -*- C++ -*- dynamic memory management header.
2
3// Copyright (C) 1994-2024 Free Software Foundation, Inc.
4
5// This file is part of GCC.
6//
7// GCC is free software; you can redistribute it and/or modify
8// it under the terms of the GNU General Public License as published by
9// the Free Software Foundation; either version 3, or (at your option)
10// any later version.
11//
12// GCC is distributed in the hope that it will be useful,
13// but WITHOUT ANY WARRANTY; without even the implied warranty of
14// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15// GNU General Public License for more details.
16//
17// Under Section 7 of GPL version 3, you are granted additional
18// permissions described in the GCC Runtime Library Exception, version
19// 3.1, as published by the Free Software Foundation.
20
21// You should have received a copy of the GNU General Public License and
22// a copy of the GCC Runtime Library Exception along with this program;
23// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
24// <http://www.gnu.org/licenses/>.
25
26/** @file new
27 * This is a Standard C++ Library header.
28 *
29 * The header @c new defines several functions to manage dynamic memory and
30 * handling memory allocation errors; see
31 * https://gcc.gnu.org/onlinedocs/libstdc++/manual/dynamic_memory.html
32 * for more.
33 */
34
35#ifndef _NEW
36#define _NEW
37
38#ifdef _GLIBCXX_SYSHDR
39#pragma GCC system_header
40#endif
41
42#include <bits/c++config.h>
43#include <bits/exception.h>
44
45#define __glibcxx_want_launder
46#define __glibcxx_want_hardware_interference_size
47#define __glibcxx_want_destroying_delete
48#define __glibcxx_want_constexpr_new
49#include <bits/version.h>
50
51#pragma GCC diagnostic push
52#pragma GCC diagnostic ignored "-Wc++11-extensions" // scoped enum
53
54#pragma GCC visibility push(default)
55
56extern "C++" {
57
58namespace std
59{
60 /**
61 * @brief Exception possibly thrown by @c new.
62 * @ingroup exceptions
63 *
64 * @c bad_alloc (or classes derived from it) is used to report allocation
65 * errors from the throwing forms of @c new. */
66 class bad_alloc : public exception
67 {
68 public:
69 bad_alloc() throw() { }
70
71#if __cplusplus >= 201103L
72 bad_alloc(const bad_alloc&) = default;
73 bad_alloc& operator=(const bad_alloc&) = default;
74#endif
75
76 // This declaration is not useless:
77 // http://gcc.gnu.org/onlinedocs/gcc-3.0.2/gcc_6.html#SEC118
78 virtual ~bad_alloc() throw();
79
80 // See comment in eh_exception.cc.
81 virtual const char* what() const throw();
82 };
83
84#if __cplusplus >= 201103L
85 class bad_array_new_length : public bad_alloc
86 {
87 public:
88 bad_array_new_length() throw() { }
89
90 // This declaration is not useless:
91 // http://gcc.gnu.org/onlinedocs/gcc-3.0.2/gcc_6.html#SEC118
92 virtual ~bad_array_new_length() throw();
93
94 // See comment in eh_exception.cc.
95 virtual const char* what() const throw();
96 };
97#endif
98
99#if __cpp_aligned_new
100 enum class align_val_t: size_t {};
101#endif
102
103 struct nothrow_t
104 {
105#if __cplusplus >= 201103L
106 explicit nothrow_t() = default;
107#endif
108 };
109
110 extern const nothrow_t nothrow;
111
112 /** If you write your own error handler to be called by @c new, it must
113 * be of this type. */
114 typedef void (*new_handler)();
115
116 /// Takes a replacement handler as the argument, returns the
117 /// previous handler.
119
120#if __cplusplus >= 201103L
121 /// Return the current new handler.
123#endif
124} // namespace std
125
126//@{
127/** These are replaceable signatures:
128 * - normal single new and delete (no arguments, throw @c bad_alloc on error)
129 * - normal array new and delete (same)
130 * - @c nothrow single new and delete (take a @c nothrow argument, return
131 * @c NULL on error)
132 * - @c nothrow array new and delete (same)
133 *
134 * Placement new and delete signatures (take a memory address argument,
135 * does nothing) may not be replaced by a user's program.
136*/
137_GLIBCXX_NODISCARD void* operator new(std::size_t)
138 _GLIBCXX_TXN_SAFE _GLIBCXX_THROW (std::bad_alloc)
139 __attribute__((__externally_visible__, __malloc__));
140_GLIBCXX_NODISCARD void* operator new[](std::size_t)
141 _GLIBCXX_TXN_SAFE _GLIBCXX_THROW (std::bad_alloc)
142 __attribute__((__externally_visible__, __malloc__));
143void operator delete(void*) _GLIBCXX_TXN_SAFE _GLIBCXX_USE_NOEXCEPT
144 __attribute__((__externally_visible__));
145void operator delete[](void*) _GLIBCXX_TXN_SAFE _GLIBCXX_USE_NOEXCEPT
146 __attribute__((__externally_visible__));
147#if __cpp_sized_deallocation
148void operator delete(void*, std::size_t)
149 _GLIBCXX_TXN_SAFE _GLIBCXX_USE_NOEXCEPT
150 __attribute__((__externally_visible__));
151void operator delete[](void*, std::size_t)
152 _GLIBCXX_TXN_SAFE _GLIBCXX_USE_NOEXCEPT
153 __attribute__((__externally_visible__));
154#endif
155_GLIBCXX_NODISCARD void* operator new(std::size_t, const std::nothrow_t&)
156 _GLIBCXX_TXN_SAFE _GLIBCXX_USE_NOEXCEPT
157 __attribute__((__externally_visible__, __alloc_size__ (1), __malloc__));
158_GLIBCXX_NODISCARD void* operator new[](std::size_t, const std::nothrow_t&)
159 _GLIBCXX_TXN_SAFE _GLIBCXX_USE_NOEXCEPT
160 __attribute__((__externally_visible__, __alloc_size__ (1), __malloc__));
161void operator delete(void*, const std::nothrow_t&)
162 _GLIBCXX_TXN_SAFE _GLIBCXX_USE_NOEXCEPT
163 __attribute__((__externally_visible__));
164void operator delete[](void*, const std::nothrow_t&)
165 _GLIBCXX_TXN_SAFE _GLIBCXX_USE_NOEXCEPT
166 __attribute__((__externally_visible__));
167#if __cpp_aligned_new
168_GLIBCXX_NODISCARD void* operator new(std::size_t, std::align_val_t)
169 _GLIBCXX_TXN_SAFE
170 __attribute__((__externally_visible__, __alloc_size__ (1), __alloc_align__ (2), __malloc__));
171_GLIBCXX_NODISCARD void* operator new(std::size_t, std::align_val_t, const std::nothrow_t&)
172 _GLIBCXX_TXN_SAFE _GLIBCXX_USE_NOEXCEPT
173 __attribute__((__externally_visible__, __alloc_size__ (1), __alloc_align__ (2), __malloc__));
174void operator delete(void*, std::align_val_t) _GLIBCXX_TXN_SAFE
175 _GLIBCXX_USE_NOEXCEPT __attribute__((__externally_visible__));
176void operator delete(void*, std::align_val_t, const std::nothrow_t&)
177 _GLIBCXX_TXN_SAFE
178 _GLIBCXX_USE_NOEXCEPT __attribute__((__externally_visible__));
179_GLIBCXX_NODISCARD void* operator new[](std::size_t, std::align_val_t)
180 _GLIBCXX_TXN_SAFE
181 __attribute__((__externally_visible__, __alloc_size__ (1), __alloc_align__ (2), __malloc__));
182_GLIBCXX_NODISCARD void* operator new[](std::size_t, std::align_val_t, const std::nothrow_t&)
183 _GLIBCXX_TXN_SAFE _GLIBCXX_USE_NOEXCEPT
184 __attribute__((__externally_visible__, __alloc_size__ (1), __alloc_align__ (2), __malloc__));
185void operator delete[](void*, std::align_val_t) _GLIBCXX_TXN_SAFE
186 _GLIBCXX_USE_NOEXCEPT __attribute__((__externally_visible__));
187void operator delete[](void*, std::align_val_t, const std::nothrow_t&)
188 _GLIBCXX_TXN_SAFE
189 _GLIBCXX_USE_NOEXCEPT __attribute__((__externally_visible__));
190#if __cpp_sized_deallocation
191void operator delete(void*, std::size_t, std::align_val_t) _GLIBCXX_TXN_SAFE
192 _GLIBCXX_USE_NOEXCEPT __attribute__((__externally_visible__));
193void operator delete[](void*, std::size_t, std::align_val_t) _GLIBCXX_TXN_SAFE
194 _GLIBCXX_USE_NOEXCEPT __attribute__((__externally_visible__));
195#endif // __cpp_sized_deallocation
196#endif // __cpp_aligned_new
197
198#if __cpp_lib_constexpr_new >= 202406L
199# define _GLIBCXX_PLACEMENT_CONSTEXPR constexpr
200#else
201# define _GLIBCXX_PLACEMENT_CONSTEXPR inline
202#endif
203
204// Default placement versions of operator new.
205_GLIBCXX_NODISCARD _GLIBCXX_PLACEMENT_CONSTEXPR
206void* operator new(std::size_t, void* __p)
207 _GLIBCXX_TXN_SAFE _GLIBCXX_USE_NOEXCEPT
208{ return __p; }
209_GLIBCXX_NODISCARD _GLIBCXX_PLACEMENT_CONSTEXPR
210void* operator new[](std::size_t, void* __p)
211 _GLIBCXX_TXN_SAFE _GLIBCXX_USE_NOEXCEPT
212{ return __p; }
213
214#undef _GLIBCXX_PLACEMENT_CONSTEXPR
215
216// Default placement versions of operator delete.
217inline void operator delete (void*, void*)
218 _GLIBCXX_TXN_SAFE _GLIBCXX_USE_NOEXCEPT
219{ }
220inline void operator delete[](void*, void*)
221 _GLIBCXX_TXN_SAFE _GLIBCXX_USE_NOEXCEPT
222{ }
223//@}
224} // extern "C++"
225
226namespace std
227{
228#ifdef __cpp_lib_launder // C++ >= 17 && HAVE_BUILTIN_LAUNDER
229 /// Pointer optimization barrier [ptr.launder]
230 template<typename _Tp>
231 [[nodiscard]] constexpr _Tp*
232 launder(_Tp* __p) noexcept
233 {
234 if constexpr (__is_same(const volatile _Tp, const volatile void))
235 static_assert(!__is_same(const volatile _Tp, const volatile void),
236 "std::launder argument must not be a void pointer");
237#if _GLIBCXX_USE_BUILTIN_TRAIT(__is_function)
238 else if constexpr (__is_function(_Tp))
239 static_assert(!__is_function(_Tp),
240 "std::launder argument must not be a function pointer");
241#endif
242 else
243 return __builtin_launder(__p);
244 return nullptr;
245 }
246#endif // __cpp_lib_launder
247
248#ifdef __cpp_lib_hardware_interference_size // C++ >= 17 && defined(gcc_dest_sz)
249 inline constexpr size_t hardware_destructive_interference_size = __GCC_DESTRUCTIVE_SIZE;
250 inline constexpr size_t hardware_constructive_interference_size = __GCC_CONSTRUCTIVE_SIZE;
251#endif // __cpp_lib_hardware_interference_size
252
253// Emitted despite the FTM potentially being undefined.
254#if __cplusplus >= 202002L
255 /// Tag type used to declare a class-specific operator delete that can
256 /// invoke the destructor before deallocating the memory.
258 {
259 explicit destroying_delete_t() = default;
260 };
261 /// Tag variable of type destroying_delete_t.
263#endif // C++20
264}
265
266#pragma GCC visibility pop
267#pragma GCC diagnostic pop
268
269#endif
ISO C++ entities toplevel namespace is std.
new_handler set_new_handler(new_handler)
Takes a replacement handler as the argument, returns the previous handler.
new_handler get_new_handler() noexcept
Return the current new handler.
constexpr destroying_delete_t destroying_delete
Tag variable of type destroying_delete_t.
Definition new:262
void(* new_handler)()
Definition new:114
Exception possibly thrown by new.
Definition new:67
virtual const char * what() const
Tag type used to declare a class-specific operator delete that can invoke the destructor before deall...
Definition new:258
Base class for all library exceptions.
Definition exception.h:62