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   // posix_memalign has additional requirement, not present on aligned_alloc:
  43   // The value of alignment shall be a power of two multiple of sizeof(void *).
  44   if (al < sizeof(void*))
  45     al = sizeof(void*);
  46   int ret = posix_memalign (&ptr, al, sz);
  47   if (ret == 0)
  48     return ptr;
  49   return nullptr;
  50 }
  51 #elif _GLIBCXX_HAVE_MEMALIGN
  52 #if _GLIBCXX_HOSTED
  53 #include <malloc.h>
  54 #else
  55 extern "C" void *memalign(std::size_t boundary, std::size_t size);
  56 #endif
  57 static inline void*
  58 aligned_alloc (std::size_t al, std::size_t sz)
  59 {
  60 #ifdef __sun
  61   // Solaris 10 memalign requires that alignment is greater than or equal to
  62   // the size of a word.
  63   if (al < sizeof(int))
  64     al = sizeof(int);
  65 #endif
  66   return memalign (al, sz);
  67 }
  68 #else // !HAVE__ALIGNED_MALLOC && !HAVE_POSIX_MEMALIGN && !HAVE_MEMALIGN
  69 #include <stdint.h>
  70 // The C library doesn't provide any aligned allocation functions, define one.
  71 // This is a modified version of code from gcc/config/i386/gmm_malloc.h
  72 static inline void*
  73 aligned_alloc (std::size_t al, std::size_t sz)
  74 {
  75   // We need extra bytes to store the original value returned by malloc.
  76   if (al < sizeof(void*))
  77     al = sizeof(void*);
  78   void* const malloc_ptr = malloc(sz + al);
  79   if (!malloc_ptr)
  80     return nullptr;
  81   // Align to the requested value, leaving room for the original malloc value.
  82   void* const aligned_ptr = (void *) (((uintptr_t) malloc_ptr + al) & -al);
  83
  84   // Store the original malloc value where it can be found by operator delete.
  85   ((void **) aligned_ptr)[-1] = malloc_ptr;
  86
  87   return aligned_ptr;
  88 }
  89 #endif
  90 #endif
  91
  92 _GLIBCXX_WEAK_DEFINITION void *
  93 operator new (std::size_t sz, std::align_val_t al)
  94 {
  95   void *p;
  96   std::size_t align = (std::size_t)al;
  97
  98   /* Alignment must be a power of two.  */
  99   /* XXX This should be checked by the compiler (PR 86878).  */
 100   if (__builtin_expect (align & (align - 1), false))
 101     _GLIBCXX_THROW_OR_ABORT(bad_alloc());
 102
 103   /* malloc (0) is unpredictable; avoid it.  */
 104   if (__builtin_expect (sz == 0, false))
 105     sz = 1;
 106
 107 #if _GLIBCXX_HAVE_ALIGNED_ALLOC
 108 # ifdef _AIX
 109   /* AIX 7.2.0.0 aligned_alloc incorrectly has posix_memalign's requirement
 110    * that alignment is a multiple of sizeof(void*).  */
 111   if (align < sizeof(void*))
 112     align = sizeof(void*);
 113 # endif
 114   /* C11: the value of size shall be an integral multiple of alignment.  */
 115   if (std::size_t rem = sz & (align - 1))
 116     sz += align - rem;
 117 #endif
 118
 119   while (__builtin_expect ((p = aligned_alloc (align, sz)) == 0, false))
 120     {
 121       new_handler handler = std::get_new_handler ();
 122       if (! handler)
 123         _GLIBCXX_THROW_OR_ABORT(bad_alloc());
 124       handler ();
 125     }
 126
 127   return p;
 128 }