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

   1 // -*- C++ -*- Exception handling and frame unwind runtime interface routines.
   2 // Copyright (C) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
   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 #ifndef _UNWIND_CXX_H
  30 #define _UNWIND_CXX_H 1
  31
  32 // Level 2: C++ ABI
  33
  34 #include <typeinfo>
  35 #include <exception>
  36 #include <cstddef>
  37 #include "unwind.h"
  38 #include <bits/atomic_word.h>
  39
  40 #pragma GCC visibility push(default)
  41
  42 namespace __cxxabiv1
  43 {
  44
  45 // A primary C++ exception object consists of a header, which is a wrapper
  46 // around an unwind object header with additional C++ specific information,
  47 // followed by the exception object itself.
  48
  49 struct __cxa_exception
  50 {
  51   // Manage the exception object itself.
  52   std::type_info *exceptionType;
  53   void (*exceptionDestructor)(void *);
  54
  55   // The C++ standard has entertaining rules wrt calling set_terminate
  56   // and set_unexpected in the middle of the exception cleanup process.
  57   std::unexpected_handler unexpectedHandler;
  58   std::terminate_handler terminateHandler;
  59
  60   // The caught exception stack threads through here.
  61   __cxa_exception *nextException;
  62
  63   // How many nested handlers have caught this exception.  A negated
  64   // value is a signal that this object has been rethrown.
  65   int handlerCount;
  66
  67 #ifdef __ARM_EABI_UNWINDER__
  68   // Stack of exceptions in cleanups.
  69   __cxa_exception* nextPropagatingException;
  70
  71   // The nuber of active cleanup handlers for this exception.
  72   int propagationCount;
  73 #else
  74   // Cache parsed handler data from the personality routine Phase 1
  75   // for Phase 2 and __cxa_call_unexpected.
  76   int handlerSwitchValue;
  77   const unsigned char *actionRecord;
  78   const unsigned char *languageSpecificData;
  79   _Unwind_Ptr catchTemp;
  80   void *adjustedPtr;
  81 #endif
  82
  83   // The generic exception header.  Must be last.
  84   _Unwind_Exception unwindHeader;
  85 };
  86
  87 struct __cxa_refcounted_exception
  88 {
  89   // Manage this header.
  90   _Atomic_word referenceCount;
  91   // __cxa_exception must be last, and no padding can be after it.
  92   __cxa_exception exc;
  93 };
  94
  95 // A dependent C++ exception object consists of a wrapper around an unwind
  96 // object header with additional C++ specific information, containing a pointer
  97 // to a primary exception object.
  98
  99 struct __cxa_dependent_exception
 100 {
 101   // The primary exception this thing depends on.
 102   void *primaryException;
 103
 104   // The C++ standard has entertaining rules wrt calling set_terminate
 105   // and set_unexpected in the middle of the exception cleanup process.
 106   std::unexpected_handler unexpectedHandler;
 107   std::terminate_handler terminateHandler;
 108
 109   // The caught exception stack threads through here.
 110   __cxa_exception *nextException;
 111
 112   // How many nested handlers have caught this exception.  A negated
 113   // value is a signal that this object has been rethrown.
 114   int handlerCount;
 115
 116 #ifdef __ARM_EABI_UNWINDER__
 117   // Stack of exceptions in cleanups.
 118   __cxa_exception* nextPropagatingException;
 119
 120   // The nuber of active cleanup handlers for this exception.
 121   int propagationCount;
 122 #else
 123   // Cache parsed handler data from the personality routine Phase 1
 124   // for Phase 2 and __cxa_call_unexpected.
 125   int handlerSwitchValue;
 126   const unsigned char *actionRecord;
 127   const unsigned char *languageSpecificData;
 128   _Unwind_Ptr catchTemp;
 129   void *adjustedPtr;
 130 #endif
 131
 132   // The generic exception header.  Must be last.
 133   _Unwind_Exception unwindHeader;
 134 };
 135
 136 // Each thread in a C++ program has access to a __cxa_eh_globals object.
 137 struct __cxa_eh_globals
 138 {
 139   __cxa_exception *caughtExceptions;
 140   unsigned int uncaughtExceptions;
 141 #ifdef __ARM_EABI_UNWINDER__
 142   __cxa_exception* propagatingExceptions;
 143 #endif
 144 };
 145
 146
 147 // The __cxa_eh_globals for the current thread can be obtained by using
 148 // either of the following functions.  The "fast" version assumes at least
 149 // one prior call of __cxa_get_globals has been made from the current
 150 // thread, so no initialization is necessary.
 151 extern "C" __cxa_eh_globals *__cxa_get_globals () throw()
 152   __attribute__ ((__const__));
 153 extern "C" __cxa_eh_globals *__cxa_get_globals_fast () throw()
 154   __attribute__ ((__const__));
 155
 156 // Allocate memory for the primary exception plus the thrown object.
 157 extern "C" void *__cxa_allocate_exception(std::size_t thrown_size) throw();
 158
 159 // Free the space allocated for the primary exception.
 160 extern "C" void __cxa_free_exception(void *thrown_exception) throw();
 161
 162 // Allocate memory for a dependent exception.
 163 extern "C" __cxa_dependent_exception*
 164 __cxa_allocate_dependent_exception() throw();
 165
 166 // Free the space allocated for the dependent exception.
 167 extern "C" void
 168 __cxa_free_dependent_exception(__cxa_dependent_exception *ex) throw();
 169
 170 // Throw the exception.
 171 extern "C" void __cxa_throw (void *thrown_exception,
 172                              std::type_info *tinfo,
 173                              void (*dest) (void *))
 174   __attribute__((__noreturn__));
 175
 176 // Used to implement exception handlers.
 177 extern "C" void *__cxa_get_exception_ptr (void *) throw()
 178   __attribute__ ((__pure__));
 179 extern "C" void *__cxa_begin_catch (void *) throw();
 180 extern "C" void __cxa_end_catch ();
 181 extern "C" void __cxa_rethrow () __attribute__((__noreturn__));
 182
 183 // These facilitate code generation for recurring situations.
 184 extern "C" void __cxa_bad_cast () __attribute__((__noreturn__));
 185 extern "C" void __cxa_bad_typeid () __attribute__((__noreturn__));
 186
 187 // @@@ These are not directly specified by the IA-64 C++ ABI.
 188
 189 // Handles re-checking the exception specification if unexpectedHandler
 190 // throws, and if bad_exception needs to be thrown.  Called from the
 191 // compiler.
 192 extern "C" void __cxa_call_unexpected (void *) __attribute__((__noreturn__));
 193 extern "C" void __cxa_call_terminate (_Unwind_Exception*) throw ()
 194   __attribute__((__noreturn__));
 195
 196 #ifdef __ARM_EABI_UNWINDER__
 197 // Arm EABI specified routines.
 198 typedef enum {
 199   ctm_failed = 0,
 200   ctm_succeeded = 1,
 201   ctm_succeeded_with_ptr_to_base = 2
 202 } __cxa_type_match_result;
 203 extern "C" __cxa_type_match_result __cxa_type_match(_Unwind_Exception*,
 204                                                     const std::type_info*,
 205                                                     bool, void**);
 206 extern "C" bool __cxa_begin_cleanup (_Unwind_Exception*);
 207 extern "C" void __cxa_end_cleanup (void);
 208 #endif
 209
 210 // Invokes given handler, dying appropriately if the user handler was
 211 // so inconsiderate as to return.
 212 extern void __terminate(std::terminate_handler) throw ()
 213   __attribute__((__noreturn__));
 214 extern void __unexpected(std::unexpected_handler)
 215   __attribute__((__noreturn__));
 216
 217 // The current installed user handlers.
 218 extern std::terminate_handler __terminate_handler;
 219 extern std::unexpected_handler __unexpected_handler;
 220
 221 // These are explicitly GNU C++ specific.
 222
 223 // Acquire the C++ exception header from the C++ object.
 224 static inline __cxa_exception *
 225 __get_exception_header_from_obj (void *ptr)
 226 {
 227   return reinterpret_cast<__cxa_exception *>(ptr) - 1;
 228 }
 229
 230 // Acquire the C++ exception header from the generic exception header.
 231 static inline __cxa_exception *
 232 __get_exception_header_from_ue (_Unwind_Exception *exc)
 233 {
 234   return reinterpret_cast<__cxa_exception *>(exc + 1) - 1;
 235 }
 236
 237 // Acquire the C++ refcounted exception header from the C++ object.
 238 static inline __cxa_refcounted_exception *
 239 __get_refcounted_exception_header_from_obj (void *ptr)
 240 {
 241   return reinterpret_cast<__cxa_refcounted_exception *>(ptr) - 1;
 242 }
 243
 244 // Acquire the C++ refcounted exception header from the generic exception
 245 // header.
 246 static inline __cxa_refcounted_exception *
 247 __get_refcounted_exception_header_from_ue (_Unwind_Exception *exc)
 248 {
 249   return reinterpret_cast<__cxa_refcounted_exception *>(exc + 1) - 1;
 250 }
 251
 252 static inline __cxa_dependent_exception *
 253 __get_dependent_exception_from_ue (_Unwind_Exception *exc)
 254 {
 255   return reinterpret_cast<__cxa_dependent_exception *>(exc + 1) - 1;
 256 }
 257
 258 #ifdef __ARM_EABI_UNWINDER__
 259 static inline bool
 260 __is_gxx_exception_class(_Unwind_Exception_Class c)
 261 {
 262   // TODO: Take advantage of the fact that c will always be word aligned.
 263   return c[0] == 'G'
 264          && c[1] == 'N'
 265          && c[2] == 'U'
 266          && c[3] == 'C'
 267          && c[4] == 'C'
 268          && c[5] == '+'
 269          && c[6] == '+'
 270          && (c[7] == '\0' || c[7] == '\x01');
 271 }
 272
 273 // Only checks for primary or dependent, but not that it is a C++ exception at
 274 // all.
 275 static inline bool
 276 __is_dependent_exception(_Unwind_Exception_Class c)
 277 {
 278   return c[7] == '\x01';
 279 }
 280
 281 static inline void
 282 __GXX_INIT_PRIMARY_EXCEPTION_CLASS(_Unwind_Exception_Class c)
 283 {
 284   c[0] = 'G';
 285   c[1] = 'N';
 286   c[2] = 'U';
 287   c[3] = 'C';
 288   c[4] = 'C';
 289   c[5] = '+';
 290   c[6] = '+';
 291   c[7] = '\0';
 292 }
 293
 294 static inline void
 295 __GXX_INIT_DEPENDENT_EXCEPTION_CLASS(_Unwind_Exception_Class c)
 296 {
 297   c[0] = 'G';
 298   c[1] = 'N';
 299   c[2] = 'U';
 300   c[3] = 'C';
 301   c[4] = 'C';
 302   c[5] = '+';
 303   c[6] = '+';
 304   c[7] = '\x01';
 305 }
 306
 307 static inline bool
 308 __is_gxx_forced_unwind_class(_Unwind_Exception_Class c)
 309 {
 310   return c[0] == 'G'
 311          && c[1] == 'N'
 312          && c[2] == 'U'
 313          && c[3] == 'C'
 314          && c[4] == 'F'
 315          && c[5] == 'O'
 316          && c[6] == 'R'
 317          && c[7] == '\0';
 318 }
 319
 320 static inline void
 321 __GXX_INIT_FORCED_UNWIND_CLASS(_Unwind_Exception_Class c)
 322 {
 323   c[0] = 'G';
 324   c[1] = 'N';
 325   c[2] = 'U';
 326   c[3] = 'C';
 327   c[4] = 'F';
 328   c[5] = 'O';
 329   c[6] = 'R';
 330   c[7] = '\0';
 331 }
 332
 333 static inline void*
 334 __gxx_caught_object(_Unwind_Exception* eo)
 335 {
 336   return (void*)eo->barrier_cache.bitpattern[0];
 337 }
 338 #else // !__ARM_EABI_UNWINDER__
 339 // This is the primary exception class we report -- "GNUCC++\0".
 340 const _Unwind_Exception_Class __gxx_primary_exception_class
 341 = ((((((((_Unwind_Exception_Class) 'G'
 342          << 8 | (_Unwind_Exception_Class) 'N')
 343         << 8 | (_Unwind_Exception_Class) 'U')
 344        << 8 | (_Unwind_Exception_Class) 'C')
 345       << 8 | (_Unwind_Exception_Class) 'C')
 346      << 8 | (_Unwind_Exception_Class) '+')
 347     << 8 | (_Unwind_Exception_Class) '+')
 348    << 8 | (_Unwind_Exception_Class) '\0');
 349
 350 // This is the dependent (from std::rethrow_exception) exception class we report
 351 // "GNUCC++\x01"
 352 const _Unwind_Exception_Class __gxx_dependent_exception_class
 353 = ((((((((_Unwind_Exception_Class) 'G'
 354          << 8 | (_Unwind_Exception_Class) 'N')
 355         << 8 | (_Unwind_Exception_Class) 'U')
 356        << 8 | (_Unwind_Exception_Class) 'C')
 357       << 8 | (_Unwind_Exception_Class) 'C')
 358      << 8 | (_Unwind_Exception_Class) '+')
 359     << 8 | (_Unwind_Exception_Class) '+')
 360    << 8 | (_Unwind_Exception_Class) '\x01');
 361
 362 static inline bool
 363 __is_gxx_exception_class(_Unwind_Exception_Class c)
 364 {
 365   return c == __gxx_primary_exception_class
 366       || c == __gxx_dependent_exception_class;
 367 }
 368
 369 // Only checks for primary or dependent, but not that it is a C++ exception at
 370 // all.
 371 static inline bool
 372 __is_dependent_exception(_Unwind_Exception_Class c)
 373 {
 374   return (c & 1);
 375 }
 376
 377 #define __GXX_INIT_PRIMARY_EXCEPTION_CLASS(c) c = __gxx_primary_exception_class
 378 #define __GXX_INIT_DEPENDENT_EXCEPTION_CLASS(c) \
 379   c = __gxx_dependent_exception_class
 380
 381 // GNU C++ personality routine, Version 0.
 382 extern "C" _Unwind_Reason_Code __gxx_personality_v0
 383      (int, _Unwind_Action, _Unwind_Exception_Class,
 384       struct _Unwind_Exception *, struct _Unwind_Context *);
 385
 386 // GNU C++ sjlj personality routine, Version 0.
 387 extern "C" _Unwind_Reason_Code __gxx_personality_sj0
 388      (int, _Unwind_Action, _Unwind_Exception_Class,
 389       struct _Unwind_Exception *, struct _Unwind_Context *);
 390
 391 static inline void*
 392 __gxx_caught_object(_Unwind_Exception* eo)
 393 {
 394   // Bad as it looks, this actually works for dependent exceptions too.
 395   __cxa_exception* header = __get_exception_header_from_ue (eo);
 396   return header->adjustedPtr;
 397 }
 398 #endif // !__ARM_EABI_UNWINDER__
 399
 400 static inline void*
 401 __get_object_from_ue(_Unwind_Exception* eo) throw()
 402 {
 403   return __is_dependent_exception (eo->exception_class) ?
 404     __get_dependent_exception_from_ue (eo)->primaryException :
 405     eo + 1;
 406 }
 407
 408 static inline void *
 409 __get_object_from_ambiguous_exception(__cxa_exception *p_or_d) throw()
 410 {
 411         return __get_object_from_ue (&p_or_d->unwindHeader);
 412 }
 413
 414
 415 } /* namespace __cxxabiv1 */
 416
 417 #pragma GCC visibility pop
 418
 419 #endif // _UNWIND_CXX_H