1 // -*- C++ -*- Allocate exception objects. 2 // Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006 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 2, 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 // You should have received a copy of the GNU General Public License 18 // along with GCC; see the file COPYING. If not, write to 19 // the Free Software Foundation, 51 Franklin Street, Fifth Floor, 20 // Boston, MA 02110-1301, USA. 21 22 // As a special exception, you may use this file as part of a free software 23 // library without restriction. Specifically, if other files instantiate 24 // templates or use macros or inline functions from this file, or you compile 25 // this file and link it with other files to produce an executable, this 26 // file does not by itself cause the resulting executable to be covered by 27 // the GNU General Public License. This exception does not however 28 // invalidate any other reasons why the executable file might be covered by 29 // the GNU General Public License. 30 31 // This is derived from the C++ ABI for IA-64. Where we diverge 32 // for cross-architecture compatibility are noted with "@@@". 33 34 #include <bits/c++config.h> 35 #include <cstdlib> 36 #if _GLIBCXX_HOSTED 37 #include <cstring> 38 #endif 39 #include <climits> 40 #include <exception> 41 #include "unwind-cxx.h" 42 #include <ext/concurrence.h> 43 44 #if _GLIBCXX_HOSTED 45 using std::free; 46 using std::malloc; 47 using std::memset; 48 #else 49 // In a freestanding environment, these functions may not be available 50 // -- but for now, we assume that they are. 51 extern "C" void *malloc (std::size_t); 52 extern "C" void free(void *); 53 extern "C" void *memset (void *, int, std::size_t); 54 #endif 55 56 using namespace __cxxabiv1; 57 58 // ??? How to control these parameters. 59 60 // Guess from the size of basic types how large a buffer is reasonable. 61 // Note that the basic c++ exception header has 13 pointers and 2 ints, 62 // so on a system with PSImode pointers we're talking about 56 bytes 63 // just for overhead. 64 65 #if INT_MAX == 32767 66 # define EMERGENCY_OBJ_SIZE 128 67 # define EMERGENCY_OBJ_COUNT 16 68 #elif LONG_MAX == 2147483647 69 # define EMERGENCY_OBJ_SIZE 512 70 # define EMERGENCY_OBJ_COUNT 32 71 #else 72 # define EMERGENCY_OBJ_SIZE 1024 73 # define EMERGENCY_OBJ_COUNT 64 74 #endif 75 76 #ifndef __GTHREADS 77 # undef EMERGENCY_OBJ_COUNT 78 # define EMERGENCY_OBJ_COUNT 4 79 #endif 80 81 #if INT_MAX == 32767 || EMERGENCY_OBJ_COUNT <= 32 82 typedef unsigned int bitmask_type; 83 #else 84 typedef unsigned long bitmask_type; 85 #endif 86 87 88 typedef char one_buffer[EMERGENCY_OBJ_SIZE] __attribute__((aligned)); 89 static one_buffer emergency_buffer[EMERGENCY_OBJ_COUNT]; 90 static bitmask_type emergency_used; 91 92 namespace 93 { 94 // A single mutex controlling emergency allocations. 95 __gnu_cxx::__mutex emergency_mutex; 96 } 97 98 extern "C" void * 99 __cxxabiv1::__cxa_allocate_exception(std::size_t thrown_size) throw() 100 { 101 void *ret; 102 103 thrown_size += sizeof (__cxa_exception); 104 ret = malloc (thrown_size); 105 106 if (! ret) 107 { 108 __gnu_cxx::__scoped_lock sentry(emergency_mutex); 109 110 bitmask_type used = emergency_used; 111 unsigned int which = 0; 112 113 if (thrown_size > EMERGENCY_OBJ_SIZE) 114 goto failed; 115 while (used & 1) 116 { 117 used >>= 1; 118 if (++which >= EMERGENCY_OBJ_COUNT) 119 goto failed; 120 } 121 122 emergency_used |= (bitmask_type)1 << which; 123 ret = &emergency_buffer[which][0]; 124 125 failed:; 126 127 if (!ret) 128 std::terminate (); 129 } 130 131 // We have an uncaught exception as soon as we allocate memory. This 132 // yields uncaught_exception() true during the copy-constructor that 133 // initializes the exception object. See Issue 475. 134 __cxa_eh_globals *globals = __cxa_get_globals (); 135 globals->uncaughtExceptions += 1; 136 137 memset (ret, 0, sizeof (__cxa_exception)); 138 139 return (void *)((char *)ret + sizeof (__cxa_exception)); 140 } 141 142 143 extern "C" void 144 __cxxabiv1::__cxa_free_exception(void *vptr) throw() 145 { 146 char *ptr = (char *) vptr; 147 if (ptr >= &emergency_buffer[0][0] 148 && ptr < &emergency_buffer[0][0] + sizeof (emergency_buffer)) 149 { 150 const unsigned int which 151 = (unsigned)(ptr - &emergency_buffer[0][0]) / EMERGENCY_OBJ_SIZE; 152 153 __gnu_cxx::__scoped_lock sentry(emergency_mutex); 154 emergency_used &= ~((bitmask_type)1 << which); 155 } 156 else 157 free (ptr - sizeof (__cxa_exception)); 158 } 159