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 #if ! _GLIBCXX_HOSTED 47 extern "C" 48 { 49 # if _GLIBCXX_HAVE_ALIGNED_ALLOC 50 void *aligned_alloc(size_t alignment, size_t size); 51 # elif _GLIBCXX_HAVE__ALIGNED_MALLOC 52 void *_aligned_malloc(size_t size, size_t alignment); 53 # elif _GLIBCXX_HAVE_POSIX_MEMALIGN 54 void *posix_memalign(void **, size_t alignment, size_t size); 55 # elif _GLIBCXX_HAVE_MEMALIGN 56 void *memalign(size_t alignment, size_t size); 57 # endif 58 } 59 #endif 60 61 namespace __gnu_cxx { 62 #if _GLIBCXX_HAVE_ALIGNED_ALLOC 63 using ::aligned_alloc; 64 #elif _GLIBCXX_HAVE__ALIGNED_MALLOC 65 static inline void* 66 aligned_alloc (std::size_t al, std::size_t sz) 67 { return _aligned_malloc(sz, al); } 68 #elif _GLIBCXX_HAVE_POSIX_MEMALIGN 69 static inline void* 70 aligned_alloc (std::size_t al, std::size_t sz) 71 { 72 void *ptr; 73 // posix_memalign has additional requirement, not present on aligned_alloc: 74 // The value of alignment shall be a power of two multiple of sizeof(void *). 75 if (al < sizeof(void*)) 76 al = sizeof(void*); 77 int ret = posix_memalign (&ptr, al, sz); 78 if (ret == 0) 79 return ptr; 80 return nullptr; 81 } 82 #elif _GLIBCXX_HAVE_MEMALIGN 83 static inline void* 84 aligned_alloc (std::size_t al, std::size_t sz) 85 { 86 #ifdef __sun 87 // Solaris 10 memalign requires that alignment is greater than or equal to 88 // the size of a word. 89 if (al < sizeof(int)) 90 al = sizeof(int); 91 #endif 92 return memalign (al, sz); 93 } 94 #else // !HAVE__ALIGNED_MALLOC && !HAVE_POSIX_MEMALIGN && !HAVE_MEMALIGN 95 // The C library doesn't provide any aligned allocation functions, define one. 96 // This is a modified version of code from gcc/config/i386/gmm_malloc.h 97 static inline void* 98 aligned_alloc (std::size_t al, std::size_t sz) 99 { 100 // We need extra bytes to store the original value returned by malloc. 101 if (al < sizeof(void*)) 102 al = sizeof(void*); 103 void* const malloc_ptr = malloc(sz + al); 104 if (!malloc_ptr) 105 return nullptr; 106 // Align to the requested value, leaving room for the original malloc value. 107 void* const aligned_ptr = (void *) (((uintptr_t) malloc_ptr + al) & -al); 108 109 // Store the original malloc value where it can be found by operator delete. 110 ((void **) aligned_ptr)[-1] = malloc_ptr; 111 112 return aligned_ptr; 113 } 114 #endif 115 } // namespace __gnu_cxx 116 117 _GLIBCXX_WEAK_DEFINITION void * 118 operator new (std::size_t sz, std::align_val_t al) 119 { 120 std::size_t align = (std::size_t)al; 121 122 /* Alignment must be a power of two. */ 123 /* XXX This should be checked by the compiler (PR 86878). */ 124 if (__builtin_expect (!std::__ispow2(align), false)) 125 _GLIBCXX_THROW_OR_ABORT(bad_alloc()); 126 127 /* malloc (0) is unpredictable; avoid it. */ 128 if (__builtin_expect (sz == 0, false)) 129 sz = 1; 130 131 #if _GLIBCXX_HAVE_ALIGNED_ALLOC 132 # if defined _AIX || defined __APPLE__ 133 /* AIX 7.2.0.0 aligned_alloc incorrectly has posix_memalign's requirement 134 * that alignment is a multiple of sizeof(void*). 135 * OS X 10.15 has the same requirement. */ 136 if (align < sizeof(void*)) 137 align = sizeof(void*); 138 # endif 139 /* C11: the value of size shall be an integral multiple of alignment. */ 140 sz = (sz + align - 1) & ~(align - 1); 141 #endif 142 143 void *p; 144 145 while ((p = __gnu_cxx::aligned_alloc (align, sz)) == nullptr) 146 { 147 new_handler handler = std::get_new_handler (); 148 if (! handler) 149 _GLIBCXX_THROW_OR_ABORT(bad_alloc()); 150 handler (); 151 } 152 153 return p; 154 } 155