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

   1 // Support routines for the -*- C++ -*- dynamic memory management.
   2
   3 // Copyright (C) 1997-2018 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 <bits/exception_defines.h>
  29 #include "new"
  30
  31 using std::new_handler;
  32 using std::bad_alloc;
  33
  34 #if !_GLIBCXX_HAVE_ALIGNED_ALLOC
  35 #if _GLIBCXX_HAVE__ALIGNED_MALLOC
  36 #define aligned_alloc(al,sz) _aligned_malloc(sz,al)
  37 #elif _GLIBCXX_HAVE_POSIX_MEMALIGN
  38 static inline void*
  39 aligned_alloc (std::size_t al, std::size_t sz)
  40 {
  41   void *ptr;
  42   // The value of alignment shall be a power of two multiple of sizeof(void *).
  43   if (al < sizeof(void*))
  44     al = sizeof(void*);
  45   int ret = posix_memalign (&ptr, al, sz);
  46   if (ret == 0)
  47     return ptr;
  48   return nullptr;
  49 }
  50 #elif _GLIBCXX_HAVE_MEMALIGN
  51 #if _GLIBCXX_HOSTED
  52 #include <malloc.h>
  53 #else
  54 extern "C" void *memalign(std::size_t boundary, std::size_t size);
  55 #endif
  56 #define aligned_alloc memalign
  57 #else
  58 #include <stdint.h>
  59 // The C library doesn't provide any aligned allocation functions, define one.
  60 // This is a modified version of code from gcc/config/i386/gmm_malloc.h
  61 static inline void*
  62 aligned_alloc (std::size_t al, std::size_t sz)
  63 {
  64   // Alignment must be a power of two.
  65   if (al & (al - 1))
  66     return nullptr;
  67   else if (!sz)
  68     return nullptr;
  69
  70   // We need extra bytes to store the original value returned by malloc.
  71   if (al < sizeof(void*))
  72     al = sizeof(void*);
  73   void* const malloc_ptr = malloc(sz + al);
  74   if (!malloc_ptr)
  75     return nullptr;
  76   // Align to the requested value, leaving room for the original malloc value.
  77   void* const aligned_ptr = (void *) (((uintptr_t) malloc_ptr + al) & -al);
  78
  79   // Store the original malloc value where it can be found by operator delete.
  80   ((void **) aligned_ptr)[-1] = malloc_ptr;
  81
  82   return aligned_ptr;
  83 }
  84 #endif
  85 #endif
  86
  87 _GLIBCXX_WEAK_DEFINITION void *
  88 operator new (std::size_t sz, std::align_val_t al)
  89 {
  90   void *p;
  91   std::size_t align = (std::size_t)al;
  92
  93   /* malloc (0) is unpredictable; avoid it.  */
  94   if (sz == 0)
  95     sz = 1;
  96
  97 #if _GLIBCXX_HAVE_ALIGNED_ALLOC
  98   /* C11: the value of size shall be an integral multiple of alignment.  */
  99   if (std::size_t rem = sz & (align - 1))
 100     sz += align - rem;
 101 #endif
 102
 103   while (__builtin_expect ((p = aligned_alloc (align, sz)) == 0, false))
 104     {
 105       new_handler handler = std::get_new_handler ();
 106       if (! handler)
 107         _GLIBCXX_THROW_OR_ABORT(bad_alloc());
 108       handler ();
 109     }
 110
 111   return p;
 112 }