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 "new"
30
31 #if !_GLIBCXX_HAVE_ALIGNED_ALLOC && !_GLIBCXX_HAVE__ALIGNED_MALLOC \
32 && !_GLIBCXX_HAVE_POSIX_MEMALIGN && _GLIBCXX_HAVE_MEMALIGN
33 # if _GLIBCXX_HOSTED && __has_include(<malloc.h>)
34 // Some C libraries declare memalign in <malloc.h>
35 # include <malloc.h>
36 # else
37 extern "C" void *memalign(std::size_t boundary, std::size_t size);
38 # endif
39 #endif
40
41 using std::new_handler;
42 using std::bad_alloc;
43
44 #if ! _GLIBCXX_HOSTED
45 using std::size_t;
46 extern "C"
47 {
48 # if _GLIBCXX_HAVE_ALIGNED_ALLOC
49 void *aligned_alloc(size_t alignment, size_t size);
50 # elif _GLIBCXX_HAVE__ALIGNED_MALLOC
51 void *_aligned_malloc(size_t size, size_t alignment);
52 # elif _GLIBCXX_HAVE_POSIX_MEMALIGN
53 void *posix_memalign(void **, size_t alignment, size_t size);
54 # elif _GLIBCXX_HAVE_MEMALIGN
55 void *memalign(size_t alignment, size_t size);
56 # endif
57 }
58 #endif
59
60 namespace __gnu_cxx {
61 #if _GLIBCXX_HAVE_ALIGNED_ALLOC
62 using ::aligned_alloc;
63 #elif _GLIBCXX_HAVE__ALIGNED_MALLOC
64 static inline void*
65 aligned_alloc (std::size_t al, std::size_t sz)
66 { return _aligned_malloc(sz, al); }
67 #elif _GLIBCXX_HAVE_POSIX_MEMALIGN
68 static inline void*
69 aligned_alloc (std::size_t al, std::size_t sz)
70 {
71 void *ptr;
72 // posix_memalign has additional requirement, not present on aligned_alloc:
73 // The value of alignment shall be a power of two multiple of sizeof(void *).
74 if (al < sizeof(void*))
75 al = sizeof(void*);
76 int ret = posix_memalign (&ptr, al, sz);
77 if (ret == 0)
78 return ptr;
79 return nullptr;
80 }
81 #elif _GLIBCXX_HAVE_MEMALIGN
82 static inline void*
83 aligned_alloc (std::size_t al, std::size_t sz)
84 {
85 #ifdef __sun
86 // Solaris 10 memalign requires that alignment is greater than or equal to
87 // the size of a word.
88 if (al < sizeof(int))
89 al = sizeof(int);
90 #endif
91 return memalign (al, sz);
92 }
93 #else // !HAVE__ALIGNED_MALLOC && !HAVE_POSIX_MEMALIGN && !HAVE_MEMALIGN
94 // The C library doesn't provide any aligned allocation functions, define one.
95 // This is a modified version of code from gcc/config/i386/gmm_malloc.h
96 static inline void*
97 aligned_alloc (std::size_t al, std::size_t sz)
98 {
99 // We need extra bytes to store the original value returned by malloc.
100 if (al < sizeof(void*))
101 al = sizeof(void*);
102 void* const malloc_ptr = malloc(sz + al);
103 if (!malloc_ptr)
104 return nullptr;
105 // Align to the requested value, leaving room for the original malloc value.
106 void* const aligned_ptr = (void *) (((uintptr_t) malloc_ptr + al) & -al);
107
108 // Store the original malloc value where it can be found by operator delete.
109 ((void **) aligned_ptr)[-1] = malloc_ptr;
110
111 return aligned_ptr;
112 }
113 #endif
114 } // namespace __gnu_cxx
115
116 _GLIBCXX_WEAK_DEFINITION void *
operator new(std::size_t sz,std::align_val_t al)117 operator new (std::size_t sz, std::align_val_t al)
118 {
119 void *p;
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 (align & (align - 1), 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 if (std::size_t rem = sz & (align - 1))
141 sz += align - rem;
142 #endif
143
144 using __gnu_cxx::aligned_alloc;
145 while (__builtin_expect ((p = aligned_alloc (align, sz)) == 0, false))
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