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 } 139