libstdc++-v3/libsupc++/new_opa.cc

   1 // Support routines for the -*- C++ -*- dynamic memory management.
   2
   3 // Copyright (C) 1997-2019 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 #include <bits/c++config.h>
  27 #include <stdlib.h>
  28 #include <stdint.h>
  29 #include <bits/exception_defines.h>
  30 #include <bit>
  31 #include "new"
  32
  33 #if !_GLIBCXX_HAVE_ALIGNED_ALLOC && !_GLIBCXX_HAVE__ALIGNED_MALLOC \
  34   && !_GLIBCXX_HAVE_POSIX_MEMALIGN && _GLIBCXX_HAVE_MEMALIGN
  35 # if _GLIBCXX_HOSTED && __has_include(<malloc.h>)
  36 // Some C libraries declare memalign in <malloc.h>
  37 #  include <malloc.h>
  38 # else
  39 extern "C" void *memalign(std::size_t boundary, std::size_t size);
  40 # endif
  41 #endif
  42
  43 using std::new_handler;
  44 using std::bad_alloc;
  45
  46 namespace __gnu_cxx {
  47 #if _GLIBCXX_HAVE_ALIGNED_ALLOC
  48 using ::aligned_alloc;
  49 #elif _GLIBCXX_HAVE__ALIGNED_MALLOC
  50 static inline void*
  51 aligned_alloc (std::size_t al, std::size_t sz)
  52 { return _aligned_malloc(sz, al); }
  53 #elif _GLIBCXX_HAVE_POSIX_MEMALIGN
  54 static inline void*
  55 aligned_alloc (std::size_t al, std::size_t sz)
  56 {
  57   void *ptr;
  58   // posix_memalign has additional requirement, not present on aligned_alloc:
  59   // The value of alignment shall be a power of two multiple of sizeof(void *).
  60   if (al < sizeof(void*))
  61     al = sizeof(void*);
  62   int ret = posix_memalign (&ptr, al, sz);
  63   if (ret == 0)
  64     return ptr;
  65   return nullptr;
  66 }
  67 #elif _GLIBCXX_HAVE_MEMALIGN
  68 static inline void*
  69 aligned_alloc (std::size_t al, std::size_t sz)
  70 {
  71   return memalign (al, sz);
  72 }
  73 #else // !HAVE__ALIGNED_MALLOC && !HAVE_POSIX_MEMALIGN && !HAVE_MEMALIGN
  74 // The C library doesn't provide any aligned allocation functions, define one.
  75 // This is a modified version of code from gcc/config/i386/gmm_malloc.h
  76 static inline void*
  77 aligned_alloc (std::size_t al, std::size_t sz)
  78 {
  79   // We need extra bytes to store the original value returned by malloc.
  80   if (al < sizeof(void*))
  81     al = sizeof(void*);
  82   void* const malloc_ptr = malloc(sz + al);
  83   if (!malloc_ptr)
  84     return nullptr;
  85   // Align to the requested value, leaving room for the original malloc value.
  86   void* const aligned_ptr = (void *) (((uintptr_t) malloc_ptr + al) & -al);
  87
  88   // Store the original malloc value where it can be found by operator delete.
  89   ((void **) aligned_ptr)[-1] = malloc_ptr;
  90
  91   return aligned_ptr;
  92 }
  93 #endif
  94 } // namespace __gnu_cxx
  95
  96 _GLIBCXX_WEAK_DEFINITION void *
  97 operator new (std::size_t sz, std::align_val_t al)
  98 {
  99   std::size_t align = (std::size_t)al;
 100
 101   /* Alignment must be a power of two.  */
 102   /* XXX This should be checked by the compiler (PR 86878).  */
 103   if (__builtin_expect (!std::__ispow2(align), false))
 104     _GLIBCXX_THROW_OR_ABORT(bad_alloc());
 105
 106   /* malloc (0) is unpredictable; avoid it.  */
 107   if (__builtin_expect (sz == 0, false))
 108     sz = 1;
 109
 110 #if _GLIBCXX_HAVE_ALIGNED_ALLOC
 111 # if defined _AIX || defined __APPLE__
 112   /* AIX 7.2.0.0 aligned_alloc incorrectly has posix_memalign's requirement
 113    * that alignment is a multiple of sizeof(void*).
 114    * OS X 10.15 has the same requirement.  */
 115   if (align < sizeof(void*))
 116     align = sizeof(void*);
 117 # endif
 118   /* C11: the value of size shall be an integral multiple of alignment.  */
 119   sz = (sz + align - 1) & ~(align - 1);
 120 #endif
 121
 122   void *p;
 123
 124   while ((p = __gnu_cxx::aligned_alloc (align, sz)) == nullptr)
 125     {
 126       new_handler handler = std::get_new_handler ();
 127       if (! handler)
 128         _GLIBCXX_THROW_OR_ABORT(bad_alloc());
 129       handler ();
 130     }
 131
 132   return p;
 133 }