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 <stdint.h>
  29 #include <bits/exception_defines.h>
  30 #include "new"
  31
  32 #if !_GLIBCXX_HAVE_ALIGNED_ALLOC && !_GLIBCXX_HAVE__ALIGNED_MALLOC \
  33   && !_GLIBCXX_HAVE_POSIX_MEMALIGN && _GLIBCXX_HAVE_MEMALIGN
  34 # if _GLIBCXX_HOSTED && __has_include(<malloc.h>)
  35 // Some C libraries declare memalign in <malloc.h>
  36 #  include <malloc.h>
  37 # else
  38 extern "C" void *memalign(std::size_t boundary, std::size_t size);
  39 # endif
  40 #endif
  41
  42 using std::new_handler;
  43 using std::bad_alloc;
  44
  45 namespace __gnu_cxx {
  46 #if _GLIBCXX_HAVE_ALIGNED_ALLOC
  47 using ::aligned_alloc;
  48 #elif _GLIBCXX_HAVE__ALIGNED_MALLOC
  49 static inline void*
  50 aligned_alloc (std::size_t al, std::size_t sz)
  51 { return _aligned_malloc(sz, al); }
  52 #elif _GLIBCXX_HAVE_POSIX_MEMALIGN
  53 static inline void*
  54 aligned_alloc (std::size_t al, std::size_t sz)
  55 {
  56   void *ptr;
  57   // posix_memalign has additional requirement, not present on aligned_alloc:
  58   // The value of alignment shall be a power of two multiple of sizeof(void *).
  59   if (al < sizeof(void*))
  60     al = sizeof(void*);
  61   int ret = posix_memalign (&ptr, al, sz);
  62   if (ret == 0)
  63     return ptr;
  64   return nullptr;
  65 }
  66 #elif _GLIBCXX_HAVE_MEMALIGN
  67 static inline void*
  68 aligned_alloc (std::size_t al, std::size_t sz)
  69 {
  70 #ifdef __sun
  71   // Solaris 10 memalign requires that alignment is greater than or equal to
  72   // the size of a word.
  73   if (al < sizeof(int))
  74     al = sizeof(int);
  75 #endif
  76   return memalign (al, sz);
  77 }
  78 #else // !HAVE__ALIGNED_MALLOC && !HAVE_POSIX_MEMALIGN && !HAVE_MEMALIGN
  79 // The C library doesn't provide any aligned allocation functions, define one.
  80 // This is a modified version of code from gcc/config/i386/gmm_malloc.h
  81 static inline void*
  82 aligned_alloc (std::size_t al, std::size_t sz)
  83 {
  84   // We need extra bytes to store the original value returned by malloc.
  85   if (al < sizeof(void*))
  86     al = sizeof(void*);
  87   void* const malloc_ptr = malloc(sz + al);
  88   if (!malloc_ptr)
  89     return nullptr;
  90   // Align to the requested value, leaving room for the original malloc value.
  91   void* const aligned_ptr = (void *) (((uintptr_t) malloc_ptr + al) & -al);
  92
  93   // Store the original malloc value where it can be found by operator delete.
  94   ((void **) aligned_ptr)[-1] = malloc_ptr;
  95
  96   return aligned_ptr;
  97 }
  98 #endif
  99 } // namespace __gnu_cxx
 100
 101 _GLIBCXX_WEAK_DEFINITION void *
 102 operator new (std::size_t sz, std::align_val_t al)
 103 {
 104   void *p;
 105   std::size_t align = (std::size_t)al;
 106
 107   /* Alignment must be a power of two.  */
 108   /* XXX This should be checked by the compiler (PR 86878).  */
 109   if (__builtin_expect (align & (align - 1), false))
 110     _GLIBCXX_THROW_OR_ABORT(bad_alloc());
 111
 112   /* malloc (0) is unpredictable; avoid it.  */
 113   if (__builtin_expect (sz == 0, false))
 114     sz = 1;
 115
 116 #if _GLIBCXX_HAVE_ALIGNED_ALLOC
 117 # ifdef _AIX
 118   /* AIX 7.2.0.0 aligned_alloc incorrectly has posix_memalign's requirement
 119    * that alignment is a multiple of sizeof(void*).  */
 120   if (align < sizeof(void*))
 121     align = sizeof(void*);
 122 # endif
 123   /* C11: the value of size shall be an integral multiple of alignment.  */
 124   if (std::size_t rem = sz & (align - 1))
 125     sz += align - rem;
 126 #endif
 127
 128   using __gnu_cxx::aligned_alloc;
 129   while (__builtin_expect ((p = aligned_alloc (align, sz)) == 0, false))
 130     {
 131       new_handler handler = std::get_new_handler ();
 132       if (! handler)
 133         _GLIBCXX_THROW_OR_ABORT(bad_alloc());
 134       handler ();
 135     }
 136
 137   return p;
 138 }