1 // -*- C++ -*- Allocate exception objects.
2 // Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2008, 2009, 2011
3 // 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 // This is derived from the C++ ABI for IA-64. Where we diverge
27 // for cross-architecture compatibility are noted with "@@@".
28
29 #include <bits/c++config.h>
30 #include <cstdlib>
31 #if _GLIBCXX_HOSTED
32 #include <cstring>
33 #endif
34 #include <climits>
35 #include <exception>
36 #include "unwind-cxx.h"
37 #include <ext/concurrence.h>
38
39 #if _GLIBCXX_HOSTED
40 using std::free;
41 using std::malloc;
42 using std::memset;
43 #else
44 // In a freestanding environment, these functions may not be available
45 // -- but for now, we assume that they are.
46 extern "C" void *malloc (std::size_t);
47 extern "C" void free(void *);
48 extern "C" void *memset (void *, int, std::size_t);
49 #endif
50
51 using namespace __cxxabiv1;
52
53 // ??? How to control these parameters.
54
55 // Guess from the size of basic types how large a buffer is reasonable.
56 // Note that the basic c++ exception header has 13 pointers and 2 ints,
57 // so on a system with PSImode pointers we're talking about 56 bytes
58 // just for overhead.
59
60 #if INT_MAX == 32767
61 # define EMERGENCY_OBJ_SIZE 128
62 # define EMERGENCY_OBJ_COUNT 16
63 #elif LONG_MAX == 2147483647
64 # define EMERGENCY_OBJ_SIZE 512
65 # define EMERGENCY_OBJ_COUNT 32
66 #else
67 # define EMERGENCY_OBJ_SIZE 1024
68 # define EMERGENCY_OBJ_COUNT 64
69 #endif
70
71 #ifndef __GTHREADS
72 # undef EMERGENCY_OBJ_COUNT
73 # define EMERGENCY_OBJ_COUNT 4
74 #endif
75
76 #if INT_MAX == 32767 || EMERGENCY_OBJ_COUNT <= 32
77 typedef unsigned int bitmask_type;
78 #else
79 typedef unsigned long bitmask_type;
80 #endif
81
82
83 typedef char one_buffer[EMERGENCY_OBJ_SIZE] __attribute__((aligned));
84 static one_buffer emergency_buffer[EMERGENCY_OBJ_COUNT];
85 static bitmask_type emergency_used;
86
87 static __cxa_dependent_exception dependents_buffer[EMERGENCY_OBJ_COUNT];
88 static bitmask_type dependents_used;
89
90 namespace
91 {
92 // A single mutex controlling emergency allocations.
93 __gnu_cxx::__mutex emergency_mutex;
94 }
95
96 extern "C" void *
__cxa_allocate_exception(std::size_t thrown_size)97 __cxxabiv1::__cxa_allocate_exception(std::size_t thrown_size) _GLIBCXX_NOTHROW
98 {
99 void *ret;
100
101 thrown_size += sizeof (__cxa_refcounted_exception);
102 ret = malloc (thrown_size);
103
104 if (! ret)
105 {
106 __gnu_cxx::__scoped_lock sentry(emergency_mutex);
107
108 bitmask_type used = emergency_used;
109 unsigned int which = 0;
110
111 if (thrown_size > EMERGENCY_OBJ_SIZE)
112 goto failed;
113 while (used & 1)
114 {
115 used >>= 1;
116 if (++which >= EMERGENCY_OBJ_COUNT)
117 goto failed;
118 }
119
120 emergency_used |= (bitmask_type)1 << which;
121 ret = &emergency_buffer[which][0];
122
123 failed:;
124
125 if (!ret)
126 std::terminate ();
127 }
128
129 memset (ret, 0, sizeof (__cxa_refcounted_exception));
130
131 return (void *)((char *)ret + sizeof (__cxa_refcounted_exception));
132 }
133
134
135 extern "C" void
__cxa_free_exception(void * vptr)136 __cxxabiv1::__cxa_free_exception(void *vptr) _GLIBCXX_NOTHROW
137 {
138 char *base = (char *) emergency_buffer;
139 char *ptr = (char *) vptr;
140 if (ptr >= base
141 && ptr < base + sizeof (emergency_buffer))
142 {
143 const unsigned int which
144 = (unsigned) (ptr - base) / EMERGENCY_OBJ_SIZE;
145
146 __gnu_cxx::__scoped_lock sentry(emergency_mutex);
147 emergency_used &= ~((bitmask_type)1 << which);
148 }
149 else
150 free (ptr - sizeof (__cxa_refcounted_exception));
151 }
152
153
154 extern "C" __cxa_dependent_exception*
__cxa_allocate_dependent_exception()155 __cxxabiv1::__cxa_allocate_dependent_exception() _GLIBCXX_NOTHROW
156 {
157 __cxa_dependent_exception *ret;
158
159 ret = static_cast<__cxa_dependent_exception*>
160 (malloc (sizeof (__cxa_dependent_exception)));
161
162 if (!ret)
163 {
164 __gnu_cxx::__scoped_lock sentry(emergency_mutex);
165
166 bitmask_type used = dependents_used;
167 unsigned int which = 0;
168
169 while (used & 1)
170 {
171 used >>= 1;
172 if (++which >= EMERGENCY_OBJ_COUNT)
173 goto failed;
174 }
175
176 dependents_used |= (bitmask_type)1 << which;
177 ret = &dependents_buffer[which];
178
179 failed:;
180
181 if (!ret)
182 std::terminate ();
183 }
184
185 memset (ret, 0, sizeof (__cxa_dependent_exception));
186
187 return ret;
188 }
189
190
191 extern "C" void
__cxa_free_dependent_exception(__cxa_dependent_exception * vptr)192 __cxxabiv1::__cxa_free_dependent_exception
193 (__cxa_dependent_exception *vptr) _GLIBCXX_NOTHROW
194 {
195 char *base = (char *) dependents_buffer;
196 char *ptr = (char *) vptr;
197 if (ptr >= base
198 && ptr < base + sizeof (dependents_buffer))
199 {
200 const unsigned int which
201 = (unsigned) (ptr - base) / sizeof (__cxa_dependent_exception);
202
203 __gnu_cxx::__scoped_lock sentry(emergency_mutex);
204 dependents_used &= ~((bitmask_type)1 << which);
205 }
206 else
207 free (vptr);
208 }
209