memory/mozalloc/cxxalloc.h

   1 /* This Source Code Form is subject to the terms of the Mozilla Public
   2  * License, v. 2.0. If a copy of the MPL was not distributed with this
   3  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   4
   5 #ifndef mozilla_cxxalloc_h
   6 #define mozilla_cxxalloc_h
   7
   8 /*
   9  * We implement the default operators new/delete as part of
  10  * libmozalloc, replacing their definitions in libstdc++.  The
  11  * operator new* definitions in libmozalloc will never return a NULL
  12  * pointer.
  13  *
  14  * Each operator new immediately below returns a pointer to memory
  15  * that can be delete'd by any of
  16  *
  17  *   (1) the matching infallible operator delete immediately below
  18  *   (2) the matching system |operator delete(void*, std::nothrow)|
  19  *   (3) the matching system |operator delete(void*) noexcept(false)|
  20  *
  21  * NB: these are declared |noexcept(false)|, though they will never
  22  * throw that exception.  This declaration is consistent with the rule
  23  * that |::operator new() noexcept(false)| will never return NULL.
  24  *
  25  * NB: mozilla::fallible can be used instead of std::nothrow.
  26  */
  27
  28 #ifndef MOZALLOC_EXPORT_NEW
  29 #  define MOZALLOC_EXPORT_NEW MFBT_API
  30 #endif
  31
  32 MOZALLOC_EXPORT_NEW void* operator new(size_t size) noexcept(false) {
  33   return moz_xmalloc(size);
  34 }
  35
  36 MOZALLOC_EXPORT_NEW void* operator new(size_t size,
  37                                        const std::nothrow_t&) noexcept(true) {
  38   return malloc_impl(size);
  39 }
  40
  41 MOZALLOC_EXPORT_NEW void* operator new[](size_t size) noexcept(false) {
  42   return moz_xmalloc(size);
  43 }
  44
  45 MOZALLOC_EXPORT_NEW void* operator new[](size_t size,
  46                                          const std::nothrow_t&) noexcept(true) {
  47   return malloc_impl(size);
  48 }
  49
  50 MOZALLOC_EXPORT_NEW void operator delete(void* ptr) noexcept(true) {
  51   return free_impl(ptr);
  52 }
  53
  54 MOZALLOC_EXPORT_NEW void operator delete(void* ptr,
  55                                          const std::nothrow_t&) noexcept(true) {
  56   return free_impl(ptr);
  57 }
  58
  59 MOZALLOC_EXPORT_NEW void operator delete[](void* ptr) noexcept(true) {
  60   return free_impl(ptr);
  61 }
  62
  63 MOZALLOC_EXPORT_NEW void operator delete[](
  64     void* ptr, const std::nothrow_t&) noexcept(true) {
  65   return free_impl(ptr);
  66 }
  67
  68 #if defined(XP_WIN)
  69 // We provide the global sized delete overloads unconditionally because the
  70 // MSVC runtime headers do, despite compiling with /Zc:sizedDealloc-
  71 MOZALLOC_EXPORT_NEW void operator delete(void* ptr,
  72                                          size_t /*size*/) noexcept(true) {
  73   return free_impl(ptr);
  74 }
  75
  76 MOZALLOC_EXPORT_NEW void operator delete[](void* ptr,
  77                                            size_t /*size*/) noexcept(true) {
  78   return free_impl(ptr);
  79 }
  80 #endif
  81
  82 #endif /* mozilla_cxxalloc_h */