1 // Support routines for the -*- C++ -*- dynamic memory management. 2 3 // Copyright (C) 1997-2020 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 <bit> 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 #if ! _GLIBCXX_HOSTED 46 using std::size_t; 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 return memalign (al, sz); 87 } 88 #else // !HAVE__ALIGNED_MALLOC && !HAVE_POSIX_MEMALIGN && !HAVE_MEMALIGN 89 // The C library doesn't provide any aligned allocation functions, define one. 90 // This is a modified version of code from gcc/config/i386/gmm_malloc.h 91 static inline void* 92 aligned_alloc (std::size_t al, std::size_t sz) 93 { 94 // We need extra bytes to store the original value returned by malloc. 95 if (al < sizeof(void*)) 96 al = sizeof(void*); 97 void* const malloc_ptr = malloc(sz + al); 98 if (!malloc_ptr) 99 return nullptr; 100 // Align to the requested value, leaving room for the original malloc value. 101 void* const aligned_ptr = (void *) (((uintptr_t) malloc_ptr + al) & -al); 102 103 // Store the original malloc value where it can be found by operator delete. 104 ((void **) aligned_ptr)[-1] = malloc_ptr; 105 106 return aligned_ptr; 107 } 108 #endif 109 } // namespace __gnu_cxx 110 111 _GLIBCXX_WEAK_DEFINITION void * 112 operator new (std::size_t sz, std::align_val_t al) 113 { 114 std::size_t align = (std::size_t)al; 115 116 /* Alignment must be a power of two. */ 117 /* XXX This should be checked by the compiler (PR 86878). */ 118 if (__builtin_expect (!std::__has_single_bit(align), false)) 119 _GLIBCXX_THROW_OR_ABORT(bad_alloc()); 120 121 /* malloc (0) is unpredictable; avoid it. */ 122 if (__builtin_expect (sz == 0, false)) 123 sz = 1; 124 125 #if _GLIBCXX_HAVE_ALIGNED_ALLOC 126 # if defined _AIX || defined __APPLE__ 127 /* AIX 7.2.0.0 aligned_alloc incorrectly has posix_memalign's requirement 128 * that alignment is a multiple of sizeof(void*). 129 * OS X 10.15 has the same requirement. */ 130 if (align < sizeof(void*)) 131 align = sizeof(void*); 132 # endif 133 /* C11: the value of size shall be an integral multiple of alignment. */ 134 sz = (sz + align - 1) & ~(align - 1); 135 #endif 136 137 void *p; 138 139 while ((p = __gnu_cxx::aligned_alloc (align, sz)) == nullptr) 140 { 141 new_handler handler = std::get_new_handler (); 142 if (! handler) 143 _GLIBCXX_THROW_OR_ABORT(bad_alloc()); 144 handler (); 145 } 146 147 return p; 148 } 149