libstdc++-v3/libsupc++/unwind-cxx.h

   1 // -*- C++ -*- Exception handling and frame unwind runtime interface routines.
   2 // Copyright (C) 2001, 2008 Free Software Foundation, Inc.
   3 //
   4 // This file is part of GCC.
   5 //
   6 // GCC is free software; you can redistribute it and/or modify
   7 // it under the terms of the GNU General Public License as published by
   8 // the Free Software Foundation; either version 2, or (at your option)
   9 // any later version.
  10 //
  11 // GCC is distributed in the hope that it will be useful,
  12 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 // GNU General Public License for more details.
  15 //
  16 // You should have received a copy of the GNU General Public License
  17 // along with GCC; see the file COPYING.  If not, write to
  18 // the Free Software Foundation, 51 Franklin Street, Fifth Floor,
  19 // Boston, MA 02110-1301, USA.
  20
  21 // As a special exception, you may use this file as part of a free software
  22 // library without restriction.  Specifically, if other files instantiate
  23 // templates or use macros or inline functions from this file, or you compile
  24 // this file and link it with other files to produce an executable, this
  25 // file does not by itself cause the resulting executable to be covered by
  26 // the GNU General Public License.  This exception does not however
  27 // invalidate any other reasons why the executable file might be covered by
  28 // the GNU General Public License.
  29
  30 // This is derived from the C++ ABI for IA-64.  Where we diverge
  31 // for cross-architecture compatibility are noted with "@@@".
  32
  33 #ifndef _UNWIND_CXX_H
  34 #define _UNWIND_CXX_H 1
  35
  36 // Level 2: C++ ABI
  37
  38 #include <typeinfo>
  39 #include <exception>
  40 #include <cstddef>
  41 #include "unwind.h"
  42 #include <ext/atomicity.h>
  43
  44 #pragma GCC visibility push(default)
  45
  46 namespace __cxxabiv1
  47 {
  48
  49 // A primary C++ exception object consists of a header, which is a wrapper
  50 // around an unwind object header with additional C++ specific information,
  51 // followed by the exception object itself.
  52
  53 struct __cxa_exception
  54 {
  55   // Manage this header.
  56   _Atomic_word referenceCount;
  57
  58   // Manage the exception object itself.
  59   std::type_info *exceptionType;
  60   void (*exceptionDestructor)(void *);
  61
  62   // The C++ standard has entertaining rules wrt calling set_terminate
  63   // and set_unexpected in the middle of the exception cleanup process.
  64   std::unexpected_handler unexpectedHandler;
  65   std::terminate_handler terminateHandler;
  66
  67   // The caught exception stack threads through here.
  68   __cxa_exception *nextException;
  69
  70   // How many nested handlers have caught this exception.  A negated
  71   // value is a signal that this object has been rethrown.
  72   int handlerCount;
  73
  74 #ifdef __ARM_EABI_UNWINDER__
  75   // Stack of exceptions in cleanups.
  76   __cxa_exception* nextPropagatingException;
  77
  78   // The nuber of active cleanup handlers for this exception.
  79   int propagationCount;
  80 #else
  81   // Cache parsed handler data from the personality routine Phase 1
  82   // for Phase 2 and __cxa_call_unexpected.
  83   int handlerSwitchValue;
  84   const unsigned char *actionRecord;
  85   const unsigned char *languageSpecificData;
  86   _Unwind_Ptr catchTemp;
  87   void *adjustedPtr;
  88 #endif
  89
  90   // The generic exception header.  Must be last.
  91   _Unwind_Exception unwindHeader;
  92 };
  93
  94 // A dependent C++ exception object consists of a wrapper around an unwind
  95 // object header with additional C++ specific information, containing a pointer
  96 // to a primary exception object.
  97
  98 struct __cxa_dependent_exception
  99 {
 100   // The primary exception this thing depends on.
 101   void *primaryException;
 102
 103   // The C++ standard has entertaining rules wrt calling set_terminate
 104   // and set_unexpected in the middle of the exception cleanup process.
 105   std::unexpected_handler unexpectedHandler;
 106   std::terminate_handler terminateHandler;
 107
 108   // The caught exception stack threads through here.
 109   __cxa_exception *nextException;
 110
 111   // How many nested handlers have caught this exception.  A negated
 112   // value is a signal that this object has been rethrown.
 113   int handlerCount;
 114
 115 #ifdef __ARM_EABI_UNWINDER__
 116   // Stack of exceptions in cleanups.
 117   __cxa_exception* nextPropagatingException;
 118
 119   // The nuber of active cleanup handlers for this exception.
 120   int propagationCount;
 121 #else
 122   // Cache parsed handler data from the personality routine Phase 1
 123   // for Phase 2 and __cxa_call_unexpected.
 124   int handlerSwitchValue;
 125   const unsigned char *actionRecord;
 126   const unsigned char *languageSpecificData;
 127   _Unwind_Ptr catchTemp;
 128   void *adjustedPtr;
 129 #endif
 130
 131   // The generic exception header.  Must be last.
 132   _Unwind_Exception unwindHeader;
 133 };
 134
 135 // Each thread in a C++ program has access to a __cxa_eh_globals object.
 136 struct __cxa_eh_globals
 137 {
 138   __cxa_exception *caughtExceptions;
 139   unsigned int uncaughtExceptions;
 140 #ifdef __ARM_EABI_UNWINDER__
 141   __cxa_exception* propagatingExceptions;
 142 #endif
 143 };
 144
 145
 146 // The __cxa_eh_globals for the current thread can be obtained by using
 147 // either of the following functions.  The "fast" version assumes at least
 148 // one prior call of __cxa_get_globals has been made from the current
 149 // thread, so no initialization is necessary.
 150 extern "C" __cxa_eh_globals *__cxa_get_globals () throw();
 151 extern "C" __cxa_eh_globals *__cxa_get_globals_fast () throw();
 152
 153 // Allocate memory for the primary exception plus the thrown object.
 154 extern "C" void *__cxa_allocate_exception(std::size_t thrown_size) throw();
 155
 156 // Free the space allocated for the primary exception.
 157 extern "C" void __cxa_free_exception(void *thrown_exception) throw();
 158
 159 // Allocate memory for a dependent exception.
 160 extern "C" __cxa_dependent_exception*
 161 __cxa_allocate_dependent_exception() throw();
 162
 163 // Free the space allocated for the dependent exception.
 164 extern "C" void
 165 __cxa_free_dependent_exception(__cxa_dependent_exception *ex) throw();
 166
 167 // Throw the exception.
 168 extern "C" void __cxa_throw (void *thrown_exception,
 169                              std::type_info *tinfo,
 170                              void (*dest) (void *))
 171      __attribute__((noreturn));
 172
 173 // Used to implement exception handlers.
 174 extern "C" void *__cxa_get_exception_ptr (void *) throw();
 175 extern "C" void *__cxa_begin_catch (void *) throw();
 176 extern "C" void __cxa_end_catch ();
 177 extern "C" void __cxa_rethrow () __attribute__((noreturn));
 178
 179 // These facilitate code generation for recurring situations.
 180 extern "C" void __cxa_bad_cast ();
 181 extern "C" void __cxa_bad_typeid ();
 182
 183 // @@@ These are not directly specified by the IA-64 C++ ABI.
 184
 185 // Handles re-checking the exception specification if unexpectedHandler
 186 // throws, and if bad_exception needs to be thrown.  Called from the
 187 // compiler.
 188 extern "C" void __cxa_call_unexpected (void *) __attribute__((noreturn));
 189 extern "C" void __cxa_call_terminate (void*) __attribute__((noreturn));
 190
 191 #ifdef __ARM_EABI_UNWINDER__
 192 // Arm EABI specified routines.
 193 typedef enum {
 194   ctm_failed = 0,
 195   ctm_succeeded = 1,
 196   ctm_succeeded_with_ptr_to_base = 2
 197 } __cxa_type_match_result;
 198 extern "C" bool __cxa_type_match(_Unwind_Exception*, const std::type_info*,
 199                                  bool, void**);
 200 extern "C" void __cxa_begin_cleanup (_Unwind_Exception*);
 201 extern "C" void __cxa_end_cleanup (void);
 202 #endif
 203
 204 // Invokes given handler, dying appropriately if the user handler was
 205 // so inconsiderate as to return.
 206 extern void __terminate(std::terminate_handler) __attribute__((noreturn));
 207 extern void __unexpected(std::unexpected_handler) __attribute__((noreturn));
 208
 209 // The current installed user handlers.
 210 extern std::terminate_handler __terminate_handler;
 211 extern std::unexpected_handler __unexpected_handler;
 212
 213 // These are explicitly GNU C++ specific.
 214
 215 // Acquire the C++ exception header from the C++ object.
 216 static inline __cxa_exception *
 217 __get_exception_header_from_obj (void *ptr)
 218 {
 219   return reinterpret_cast<__cxa_exception *>(ptr) - 1;
 220 }
 221
 222 // Acquire the C++ exception header from the generic exception header.
 223 static inline __cxa_exception *
 224 __get_exception_header_from_ue (_Unwind_Exception *exc)
 225 {
 226   return reinterpret_cast<__cxa_exception *>(exc + 1) - 1;
 227 }
 228
 229 static inline __cxa_dependent_exception *
 230 __get_dependent_exception_from_ue (_Unwind_Exception *exc)
 231 {
 232   return reinterpret_cast<__cxa_dependent_exception *>(exc + 1) - 1;
 233 }
 234
 235 #ifdef __ARM_EABI_UNWINDER__
 236 static inline bool
 237 __is_gxx_exception_class(_Unwind_Exception_Class c)
 238 {
 239   // TODO: Take advantage of the fact that c will always be word aligned.
 240   return c[0] == 'G'
 241          && c[1] == 'N'
 242          && c[2] == 'U'
 243          && c[3] == 'C'
 244          && c[4] == 'C'
 245          && c[5] == '+'
 246          && c[6] == '+'
 247          && (c[7] == '\0' || c[7] == '\x01');
 248 }
 249
 250 // Only checks for primary or dependent, but not that it is a C++ exception at
 251 // all.
 252 static inline bool
 253 __is_dependent_exception(_Unwind_Exception_Class c)
 254 {
 255   return c[7] == '\x01';
 256 }
 257
 258 static inline void
 259 __GXX_INIT_PRIMARY_EXCEPTION_CLASS(_Unwind_Exception_Class c)
 260 {
 261   c[0] = 'G';
 262   c[1] = 'N';
 263   c[2] = 'U';
 264   c[3] = 'C';
 265   c[4] = 'C';
 266   c[5] = '+';
 267   c[6] = '+';
 268   c[7] = '\0';
 269 }
 270
 271 static inline void
 272 __GXX_INIT_DEPENDENT_EXCEPTION_CLASS(_Unwind_Exception_Class c)
 273 {
 274   c[0] = 'G';
 275   c[1] = 'N';
 276   c[2] = 'U';
 277   c[3] = 'C';
 278   c[4] = 'C';
 279   c[5] = '+';
 280   c[6] = '+';
 281   c[7] = '\x01';
 282 }
 283
 284 static inline bool
 285 __is_gxx_forced_unwind_class(_Unwind_Exception_Class c)
 286 {
 287   return c[0] == 'G'
 288          && c[1] == 'N'
 289          && c[2] == 'U'
 290          && c[3] == 'C'
 291          && c[4] == 'F'
 292          && c[5] == 'O'
 293          && c[6] == 'R'
 294          && c[7] == '\0';
 295 }
 296
 297 static inline void
 298 __GXX_INIT_FORCED_UNWIND_CLASS(_Unwind_Exception_Class c)
 299 {
 300   c[0] = 'G';
 301   c[1] = 'N';
 302   c[2] = 'U';
 303   c[3] = 'C';
 304   c[4] = 'F';
 305   c[5] = 'O';
 306   c[6] = 'R';
 307   c[7] = '\0';
 308 }
 309
 310 static inline void*
 311 __gxx_caught_object(_Unwind_Exception* eo)
 312 {
 313   return (void*)eo->barrier_cache.bitpattern[0];
 314 }
 315 #else // !__ARM_EABI_UNWINDER__
 316 // This is the primary exception class we report -- "GNUCC++\0".
 317 const _Unwind_Exception_Class __gxx_primary_exception_class
 318 = ((((((((_Unwind_Exception_Class) 'G'
 319          << 8 | (_Unwind_Exception_Class) 'N')
 320         << 8 | (_Unwind_Exception_Class) 'U')
 321        << 8 | (_Unwind_Exception_Class) 'C')
 322       << 8 | (_Unwind_Exception_Class) 'C')
 323      << 8 | (_Unwind_Exception_Class) '+')
 324     << 8 | (_Unwind_Exception_Class) '+')
 325    << 8 | (_Unwind_Exception_Class) '\0');
 326
 327 // This is the dependent (from std::rethrow_exception) exception class we report
 328 // "GNUCC++\x01"
 329 const _Unwind_Exception_Class __gxx_dependent_exception_class
 330 = ((((((((_Unwind_Exception_Class) 'G'
 331          << 8 | (_Unwind_Exception_Class) 'N')
 332         << 8 | (_Unwind_Exception_Class) 'U')
 333        << 8 | (_Unwind_Exception_Class) 'C')
 334       << 8 | (_Unwind_Exception_Class) 'C')
 335      << 8 | (_Unwind_Exception_Class) '+')
 336     << 8 | (_Unwind_Exception_Class) '+')
 337    << 8 | (_Unwind_Exception_Class) '\x01');
 338
 339 static inline bool
 340 __is_gxx_exception_class(_Unwind_Exception_Class c)
 341 {
 342   return c == __gxx_primary_exception_class
 343       || c == __gxx_dependent_exception_class;
 344 }
 345
 346 // Only checks for primary or dependent, but not that it is a C++ exception at
 347 // all.
 348 static inline bool
 349 __is_dependent_exception(_Unwind_Exception_Class c)
 350 {
 351   return (c & 1);
 352 }
 353
 354 #define __GXX_INIT_PRIMARY_EXCEPTION_CLASS(c) c = __gxx_primary_exception_class
 355 #define __GXX_INIT_DEPENDENT_EXCEPTION_CLASS(c) \
 356   c = __gxx_dependent_exception_class
 357
 358 // GNU C++ personality routine, Version 0.
 359 extern "C" _Unwind_Reason_Code __gxx_personality_v0
 360      (int, _Unwind_Action, _Unwind_Exception_Class,
 361       struct _Unwind_Exception *, struct _Unwind_Context *);
 362
 363 // GNU C++ sjlj personality routine, Version 0.
 364 extern "C" _Unwind_Reason_Code __gxx_personality_sj0
 365      (int, _Unwind_Action, _Unwind_Exception_Class,
 366       struct _Unwind_Exception *, struct _Unwind_Context *);
 367
 368 static inline void*
 369 __gxx_caught_object(_Unwind_Exception* eo)
 370 {
 371   // Bad as it looks, this actually works for dependent exceptions too.
 372   __cxa_exception* header = __get_exception_header_from_ue (eo);
 373   return header->adjustedPtr;
 374 }
 375 #endif // !__ARM_EABI_UNWINDER__
 376
 377 static inline void*
 378 __get_object_from_ue(_Unwind_Exception* eo) throw()
 379 {
 380   return __is_dependent_exception (eo->exception_class) ?
 381     __get_dependent_exception_from_ue (eo)->primaryException :
 382     eo + 1;
 383 }
 384
 385 static inline void *
 386 __get_object_from_ambiguous_exception(__cxa_exception *p_or_d) throw()
 387 {
 388         return __get_object_from_ue (&p_or_d->unwindHeader);
 389 }
 390
 391
 392 } /* namespace __cxxabiv1 */
 393
 394 #pragma GCC visibility pop
 395
 396 #endif // _UNWIND_CXX_H