libstdc++-v3/libsupc++/new

   1 // The -*- C++ -*- dynamic memory management header.
   2
   3 // Copyright (C) 1994-2023 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 #pragma GCC system_header
  39
  40 #include <bits/c++config.h>
  41 #include <bits/exception.h>
  42
  43 #pragma GCC visibility push(default)
  44
  45 extern "C++" {
  46
  47 namespace std
  48 {
  49   /**
  50    *  @brief  Exception possibly thrown by @c new.
  51    *  @ingroup exceptions
  52    *
  53    *  @c bad_alloc (or classes derived from it) is used to report allocation
  54    *  errors from the throwing forms of @c new.  */
  55   class bad_alloc : public exception
  56   {
  57   public:
  58     bad_alloc() throw() { }
  59
  60 #if __cplusplus >= 201103L
  61     bad_alloc(const bad_alloc&) = default;
  62     bad_alloc& operator=(const bad_alloc&) = default;
  63 #endif
  64
  65     // This declaration is not useless:
  66     // http://gcc.gnu.org/onlinedocs/gcc-3.0.2/gcc_6.html#SEC118
  67     virtual ~bad_alloc() throw();
  68
  69     // See comment in eh_exception.cc.
  70     virtual const char* what() const throw();
  71   };
  72
  73 #if __cplusplus >= 201103L
  74   class bad_array_new_length : public bad_alloc
  75   {
  76   public:
  77     bad_array_new_length() throw() { }
  78
  79     // This declaration is not useless:
  80     // http://gcc.gnu.org/onlinedocs/gcc-3.0.2/gcc_6.html#SEC118
  81     virtual ~bad_array_new_length() throw();
  82
  83     // See comment in eh_exception.cc.
  84     virtual const char* what() const throw();
  85   };
  86 #endif
  87
  88 #if __cpp_aligned_new
  89   enum class align_val_t: size_t {};
  90 #endif
  91
  92   struct nothrow_t
  93   {
  94 #if __cplusplus >= 201103L
  95     explicit nothrow_t() = default;
  96 #endif
  97   };
  98
  99   extern const nothrow_t nothrow;
 100
 101   /** If you write your own error handler to be called by @c new, it must
 102    *  be of this type.  */
 103   typedef void (*new_handler)();
 104
 105   /// Takes a replacement handler as the argument, returns the
 106   /// previous handler.
 107   new_handler set_new_handler(new_handler) throw();
 108
 109 #if __cplusplus >= 201103L
 110   /// Return the current new handler.
 111   new_handler get_new_handler() noexcept;
 112 #endif
 113 } // namespace std
 114
 115 //@{
 116 /** These are replaceable signatures:
 117  *  - normal single new and delete (no arguments, throw @c bad_alloc on error)
 118  *  - normal array new and delete (same)
 119  *  - @c nothrow single new and delete (take a @c nothrow argument, return
 120  *    @c NULL on error)
 121  *  - @c nothrow array new and delete (same)
 122  *
 123  *  Placement new and delete signatures (take a memory address argument,
 124  *  does nothing) may not be replaced by a user's program.
 125 */
 126 _GLIBCXX_NODISCARD void* operator new(std::size_t) _GLIBCXX_THROW (std::bad_alloc)
 127   __attribute__((__externally_visible__));
 128 _GLIBCXX_NODISCARD void* operator new[](std::size_t) _GLIBCXX_THROW (std::bad_alloc)
 129   __attribute__((__externally_visible__));
 130 void operator delete(void*) _GLIBCXX_USE_NOEXCEPT
 131   __attribute__((__externally_visible__));
 132 void operator delete[](void*) _GLIBCXX_USE_NOEXCEPT
 133   __attribute__((__externally_visible__));
 134 #if __cpp_sized_deallocation
 135 void operator delete(void*, std::size_t) _GLIBCXX_USE_NOEXCEPT
 136   __attribute__((__externally_visible__));
 137 void operator delete[](void*, std::size_t) _GLIBCXX_USE_NOEXCEPT
 138   __attribute__((__externally_visible__));
 139 #endif
 140 _GLIBCXX_NODISCARD void* operator new(std::size_t, const std::nothrow_t&) _GLIBCXX_USE_NOEXCEPT
 141   __attribute__((__externally_visible__, __alloc_size__ (1), __malloc__));
 142 _GLIBCXX_NODISCARD void* operator new[](std::size_t, const std::nothrow_t&) _GLIBCXX_USE_NOEXCEPT
 143   __attribute__((__externally_visible__, __alloc_size__ (1), __malloc__));
 144 void operator delete(void*, const std::nothrow_t&) _GLIBCXX_USE_NOEXCEPT
 145   __attribute__((__externally_visible__));
 146 void operator delete[](void*, const std::nothrow_t&) _GLIBCXX_USE_NOEXCEPT
 147   __attribute__((__externally_visible__));
 148 #if __cpp_aligned_new
 149 _GLIBCXX_NODISCARD void* operator new(std::size_t, std::align_val_t)
 150   __attribute__((__externally_visible__, __alloc_size__ (1), __malloc__));
 151 _GLIBCXX_NODISCARD void* operator new(std::size_t, std::align_val_t, const std::nothrow_t&)
 152   _GLIBCXX_USE_NOEXCEPT __attribute__((__externally_visible__, __alloc_size__ (1), __malloc__));
 153 void operator delete(void*, std::align_val_t)
 154   _GLIBCXX_USE_NOEXCEPT __attribute__((__externally_visible__));
 155 void operator delete(void*, std::align_val_t, const std::nothrow_t&)
 156   _GLIBCXX_USE_NOEXCEPT __attribute__((__externally_visible__));
 157 _GLIBCXX_NODISCARD void* operator new[](std::size_t, std::align_val_t)
 158   __attribute__((__externally_visible__, __alloc_size__ (1), __malloc__));
 159 _GLIBCXX_NODISCARD void* operator new[](std::size_t, std::align_val_t, const std::nothrow_t&)
 160   _GLIBCXX_USE_NOEXCEPT __attribute__((__externally_visible__, __alloc_size__ (1), __malloc__));
 161 void operator delete[](void*, std::align_val_t)
 162   _GLIBCXX_USE_NOEXCEPT __attribute__((__externally_visible__));
 163 void operator delete[](void*, std::align_val_t, const std::nothrow_t&)
 164   _GLIBCXX_USE_NOEXCEPT __attribute__((__externally_visible__));
 165 #if __cpp_sized_deallocation
 166 void operator delete(void*, std::size_t, std::align_val_t)
 167   _GLIBCXX_USE_NOEXCEPT __attribute__((__externally_visible__));
 168 void operator delete[](void*, std::size_t, std::align_val_t)
 169   _GLIBCXX_USE_NOEXCEPT __attribute__((__externally_visible__));
 170 #endif // __cpp_sized_deallocation
 171 #endif // __cpp_aligned_new
 172
 173 // Default placement versions of operator new.
 174 _GLIBCXX_NODISCARD inline void* operator new(std::size_t, void* __p) _GLIBCXX_USE_NOEXCEPT
 175 { return __p; }
 176 _GLIBCXX_NODISCARD inline void* operator new[](std::size_t, void* __p) _GLIBCXX_USE_NOEXCEPT
 177 { return __p; }
 178
 179 // Default placement versions of operator delete.
 180 inline void operator delete  (void*, void*) _GLIBCXX_USE_NOEXCEPT { }
 181 inline void operator delete[](void*, void*) _GLIBCXX_USE_NOEXCEPT { }
 182 //@}
 183 } // extern "C++"
 184
 185 #if __cplusplus >= 201703L
 186 namespace std
 187 {
 188 #ifdef _GLIBCXX_HAVE_BUILTIN_LAUNDER
 189 #define __cpp_lib_launder 201606L
 190   /// Pointer optimization barrier [ptr.launder]
 191   template<typename _Tp>
 192     [[nodiscard]] constexpr _Tp*
 193     launder(_Tp* __p) noexcept
 194     { return __builtin_launder(__p); }
 195
 196   // The program is ill-formed if T is a function type or
 197   // (possibly cv-qualified) void.
 198
 199   template<typename _Ret, typename... _Args _GLIBCXX_NOEXCEPT_PARM>
 200     void launder(_Ret (*)(_Args...) _GLIBCXX_NOEXCEPT_QUAL) = delete;
 201   template<typename _Ret, typename... _Args _GLIBCXX_NOEXCEPT_PARM>
 202     void launder(_Ret (*)(_Args......) _GLIBCXX_NOEXCEPT_QUAL) = delete;
 203
 204   void launder(void*) = delete;
 205   void launder(const void*) = delete;
 206   void launder(volatile void*) = delete;
 207   void launder(const volatile void*) = delete;
 208 #endif // _GLIBCXX_HAVE_BUILTIN_LAUNDER
 209
 210 #ifdef __GCC_DESTRUCTIVE_SIZE
 211 # define __cpp_lib_hardware_interference_size 201703L
 212   inline constexpr size_t hardware_destructive_interference_size = __GCC_DESTRUCTIVE_SIZE;
 213   inline constexpr size_t hardware_constructive_interference_size = __GCC_CONSTRUCTIVE_SIZE;
 214 #endif // __GCC_DESTRUCTIVE_SIZE
 215 }
 216 #endif // C++17
 217
 218 #if __cplusplus > 201703L
 219 namespace std
 220 {
 221   /// Tag type used to declare a class-specific operator delete that can
 222   /// invoke the destructor before deallocating the memory.
 223   struct destroying_delete_t
 224   {
 225     explicit destroying_delete_t() = default;
 226   };
 227   /// Tag variable of type destroying_delete_t.
 228   inline constexpr destroying_delete_t destroying_delete{};
 229 }
 230 // Only define the feature test macro if the compiler supports the feature:
 231 #if __cpp_impl_destroying_delete
 232 # define __cpp_lib_destroying_delete 201806L
 233 #endif
 234 #endif // C++20
 235
 236 #pragma GCC visibility pop
 237
 238 #endif