1// -*- C++ -*- Allocate exception objects.
2// Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2008, 2009
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
40using std::free;
41using std::malloc;
42using std::memset;
43#else
44// In a freestanding environment, these functions may not be available
45// -- but for now, we assume that they are.
46extern "C" void *malloc (std::size_t);
47extern "C" void free(void *);
48extern "C" void *memset (void *, int, std::size_t);
49#endif
50
51using 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
77typedef unsigned int bitmask_type;
78#else
79typedef unsigned long bitmask_type;
80#endif
81
82
83typedef char one_buffer[EMERGENCY_OBJ_SIZE] __attribute__((aligned));
84static one_buffer emergency_buffer[EMERGENCY_OBJ_COUNT];
85static bitmask_type emergency_used;
86
87static __cxa_dependent_exception dependents_buffer[EMERGENCY_OBJ_COUNT];
88static bitmask_type dependents_used;
89
90namespace
91{
92  // A single mutex controlling emergency allocations.
93  __gnu_cxx::__mutex emergency_mutex;
94}
95
96extern "C" void *
97__cxxabiv1::__cxa_allocate_exception(std::size_t thrown_size) throw()
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  // We have an uncaught exception as soon as we allocate memory.  This
130  // yields uncaught_exception() true during the copy-constructor that
131  // initializes the exception object.  See Issue 475.
132  __cxa_eh_globals *globals = __cxa_get_globals ();
133  globals->uncaughtExceptions += 1;
134
135  memset (ret, 0, sizeof (__cxa_refcounted_exception));
136
137  return (void *)((char *)ret + sizeof (__cxa_refcounted_exception));
138}
139
140
141extern "C" void
142__cxxabiv1::__cxa_free_exception(void *vptr) throw()
143{
144  char *base = (char *) emergency_buffer;
145  char *ptr = (char *) vptr;
146  if (ptr >= base
147      && ptr < base + sizeof (emergency_buffer))
148    {
149      const unsigned int which
150	= (unsigned) (ptr - base) / EMERGENCY_OBJ_SIZE;
151
152      __gnu_cxx::__scoped_lock sentry(emergency_mutex);
153      emergency_used &= ~((bitmask_type)1 << which);
154    }
155  else
156    free (ptr - sizeof (__cxa_refcounted_exception));
157}
158
159
160extern "C" __cxa_dependent_exception*
161__cxxabiv1::__cxa_allocate_dependent_exception() throw()
162{
163  __cxa_dependent_exception *ret;
164
165  ret = static_cast<__cxa_dependent_exception*>
166    (malloc (sizeof (__cxa_dependent_exception)));
167
168  if (!ret)
169    {
170      __gnu_cxx::__scoped_lock sentry(emergency_mutex);
171
172      bitmask_type used = dependents_used;
173      unsigned int which = 0;
174
175      while (used & 1)
176	{
177	  used >>= 1;
178	  if (++which >= EMERGENCY_OBJ_COUNT)
179	    goto failed;
180	}
181
182      dependents_used |= (bitmask_type)1 << which;
183      ret = &dependents_buffer[which];
184
185    failed:;
186
187      if (!ret)
188	std::terminate ();
189    }
190
191  // We have an uncaught exception as soon as we allocate memory.  This
192  // yields uncaught_exception() true during the copy-constructor that
193  // initializes the exception object.  See Issue 475.
194  __cxa_eh_globals *globals = __cxa_get_globals ();
195  globals->uncaughtExceptions += 1;
196
197  memset (ret, 0, sizeof (__cxa_dependent_exception));
198
199  return ret;
200}
201
202
203extern "C" void
204__cxxabiv1::__cxa_free_dependent_exception
205  (__cxa_dependent_exception *vptr) throw()
206{
207  char *base = (char *) dependents_buffer;
208  char *ptr = (char *) vptr;
209  if (ptr >= base
210      && ptr < base + sizeof (dependents_buffer))
211    {
212      const unsigned int which
213	= (unsigned) (ptr - base) / sizeof (__cxa_dependent_exception);
214
215      __gnu_cxx::__scoped_lock sentry(emergency_mutex);
216      dependents_used &= ~((bitmask_type)1 << which);
217    }
218  else
219    free (vptr);
220}
221