gcc/unwind.inc

   1 /* Exception handling and frame unwind runtime interface routines. -*- C -*-
   2    Copyright (C) 2001, 2003 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 it
   7    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    In addition to the permissions in the GNU General Public License, the
  12    Free Software Foundation gives you unlimited permission to link the
  13    compiled version of this file into combinations with other programs,
  14    and to distribute those combinations without any restriction coming
  15    from the use of this file.  (The General Public License restrictions
  16    do apply in other respects; for example, they cover modification of
  17    the file, and distribution when not linked into a combined
  18    executable.)
  19
  20    GCC is distributed in the hope that it will be useful, but WITHOUT
  21    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  22    or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public
  23    License for more details.
  24
  25    You should have received a copy of the GNU General Public License
  26    along with GCC; see the file COPYING.  If not, write to the Free
  27    Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
  28    02110-1301, USA.  */
  29
  30 /* This is derived from the C++ ABI for IA-64.  Where we diverge
  31    for cross-architecture compatibility are noted with "@@@".
  32    This file is included from unwind-dw2.c or unwind-ia64.c.  */
  33
  34 /* Subroutine of _Unwind_RaiseException also invoked from _Unwind_Resume.
  35
  36    Unwind the stack calling the personality routine to find both the
  37    exception handler and intermediary cleanup code.  We'll only locate
  38    the first such frame here.  Cleanup code will call back into
  39    _Unwind_Resume and we'll continue Phase 2 there.  */
  40
  41 static _Unwind_Reason_Code
  42 _Unwind_RaiseException_Phase2(struct _Unwind_Exception *exc,
  43                               struct _Unwind_Context *context)
  44 {
  45   _Unwind_Reason_Code code;
  46
  47   while (1)
  48     {
  49       _Unwind_FrameState fs;
  50       int match_handler;
  51
  52       code = uw_frame_state_for (context, &fs);
  53
  54       /* Identify when we've reached the designated handler context.  */
  55       match_handler = (uw_identify_context (context) == exc->private_2
  56                        ? _UA_HANDLER_FRAME : 0);
  57
  58       if (code != _URC_NO_REASON)
  59         /* Some error encountered.  Usually the unwinder doesn't
  60            diagnose these and merely crashes.  */
  61         return _URC_FATAL_PHASE2_ERROR;
  62
  63       /* Unwind successful.  Run the personality routine, if any.  */
  64       if (fs.personality)
  65         {
  66           code = (*fs.personality) (1, _UA_CLEANUP_PHASE | match_handler,
  67                                     exc->exception_class, exc, context);
  68           if (code == _URC_INSTALL_CONTEXT)
  69             break;
  70           if (code != _URC_CONTINUE_UNWIND)
  71             return _URC_FATAL_PHASE2_ERROR;
  72         }
  73
  74       /* Don't let us unwind past the handler context.  */
  75       gcc_assert (!match_handler);
  76
  77       uw_update_context (context, &fs);
  78     }
  79
  80   return code;
  81 }
  82
  83 /* Raise an exception, passing along the given exception object.  */
  84
  85 _Unwind_Reason_Code
  86 _Unwind_RaiseException(struct _Unwind_Exception *exc)
  87 {
  88   struct _Unwind_Context this_context, cur_context;
  89   _Unwind_Reason_Code code;
  90
  91   /* Set up this_context to describe the current stack frame.  */
  92   uw_init_context (&this_context);
  93   cur_context = this_context;
  94
  95   /* Phase 1: Search.  Unwind the stack, calling the personality routine
  96      with the _UA_SEARCH_PHASE flag set.  Do not modify the stack yet.  */
  97   while (1)
  98     {
  99       _Unwind_FrameState fs;
 100
 101       /* Set up fs to describe the FDE for the caller of cur_context.  The
 102          first time through the loop, that means __cxa_throw.  */
 103       code = uw_frame_state_for (&cur_context, &fs);
 104
 105       if (code == _URC_END_OF_STACK)
 106         /* Hit end of stack with no handler found.  */
 107         return _URC_END_OF_STACK;
 108
 109       if (code != _URC_NO_REASON)
 110         /* Some error encountered.  Ususally the unwinder doesn't
 111            diagnose these and merely crashes.  */
 112         return _URC_FATAL_PHASE1_ERROR;
 113
 114       /* Unwind successful.  Run the personality routine, if any.  */
 115       if (fs.personality)
 116         {
 117           code = (*fs.personality) (1, _UA_SEARCH_PHASE, exc->exception_class,
 118                                     exc, &cur_context);
 119           if (code == _URC_HANDLER_FOUND)
 120             break;
 121           else if (code != _URC_CONTINUE_UNWIND)
 122             return _URC_FATAL_PHASE1_ERROR;
 123         }
 124
 125       /* Update cur_context to describe the same frame as fs.  */
 126       uw_update_context (&cur_context, &fs);
 127     }
 128
 129   /* Indicate to _Unwind_Resume and associated subroutines that this
 130      is not a forced unwind.  Further, note where we found a handler.  */
 131   exc->private_1 = 0;
 132   exc->private_2 = uw_identify_context (&cur_context);
 133
 134   cur_context = this_context;
 135   code = _Unwind_RaiseException_Phase2 (exc, &cur_context);
 136   if (code != _URC_INSTALL_CONTEXT)
 137     return code;
 138
 139   uw_install_context (&this_context, &cur_context);
 140 }
 141
 142
 143 /* Subroutine of _Unwind_ForcedUnwind also invoked from _Unwind_Resume.  */
 144
 145 static _Unwind_Reason_Code
 146 _Unwind_ForcedUnwind_Phase2 (struct _Unwind_Exception *exc,
 147                              struct _Unwind_Context *context)
 148 {
 149   _Unwind_Stop_Fn stop = (_Unwind_Stop_Fn) (_Unwind_Ptr) exc->private_1;
 150   void *stop_argument = (void *) (_Unwind_Ptr) exc->private_2;
 151   _Unwind_Reason_Code code, stop_code;
 152
 153   while (1)
 154     {
 155       _Unwind_FrameState fs;
 156       int action;
 157
 158       /* Set up fs to describe the FDE for the caller of cur_context.  */
 159       code = uw_frame_state_for (context, &fs);
 160       if (code != _URC_NO_REASON && code != _URC_END_OF_STACK)
 161         return _URC_FATAL_PHASE2_ERROR;
 162
 163       /* Unwind successful.  */
 164       action = _UA_FORCE_UNWIND | _UA_CLEANUP_PHASE;
 165       if (code == _URC_END_OF_STACK)
 166         action |= _UA_END_OF_STACK;
 167       stop_code = (*stop) (1, action, exc->exception_class, exc,
 168                            context, stop_argument);
 169       if (stop_code != _URC_NO_REASON)
 170         return _URC_FATAL_PHASE2_ERROR;
 171
 172       /* Stop didn't want to do anything.  Invoke the personality
 173          handler, if applicable, to run cleanups.  */
 174       if (code == _URC_END_OF_STACK)
 175         break;
 176
 177       if (fs.personality)
 178         {
 179           code = (*fs.personality) (1, _UA_FORCE_UNWIND | _UA_CLEANUP_PHASE,
 180                                     exc->exception_class, exc, context);
 181           if (code == _URC_INSTALL_CONTEXT)
 182             break;
 183           if (code != _URC_CONTINUE_UNWIND)
 184             return _URC_FATAL_PHASE2_ERROR;
 185         }
 186
 187       /* Update cur_context to describe the same frame as fs.  */
 188       uw_update_context (context, &fs);
 189     }
 190
 191   return code;
 192 }
 193
 194
 195 /* Raise an exception for forced unwinding.  */
 196
 197 _Unwind_Reason_Code
 198 _Unwind_ForcedUnwind (struct _Unwind_Exception *exc,
 199                       _Unwind_Stop_Fn stop, void * stop_argument)
 200 {
 201   struct _Unwind_Context this_context, cur_context;
 202   _Unwind_Reason_Code code;
 203
 204   uw_init_context (&this_context);
 205   cur_context = this_context;
 206
 207   exc->private_1 = (_Unwind_Ptr) stop;
 208   exc->private_2 = (_Unwind_Ptr) stop_argument;
 209
 210   code = _Unwind_ForcedUnwind_Phase2 (exc, &cur_context);
 211   if (code != _URC_INSTALL_CONTEXT)
 212     return code;
 213
 214   uw_install_context (&this_context, &cur_context);
 215 }
 216
 217
 218 /* Resume propagation of an existing exception.  This is used after
 219    e.g. executing cleanup code, and not to implement rethrowing.  */
 220
 221 void
 222 _Unwind_Resume (struct _Unwind_Exception *exc)
 223 {
 224   struct _Unwind_Context this_context, cur_context;
 225   _Unwind_Reason_Code code;
 226
 227   uw_init_context (&this_context);
 228   cur_context = this_context;
 229
 230   /* Choose between continuing to process _Unwind_RaiseException
 231      or _Unwind_ForcedUnwind.  */
 232   if (exc->private_1 == 0)
 233     code = _Unwind_RaiseException_Phase2 (exc, &cur_context);
 234   else
 235     code = _Unwind_ForcedUnwind_Phase2 (exc, &cur_context);
 236
 237   gcc_assert (code == _URC_INSTALL_CONTEXT);
 238
 239   uw_install_context (&this_context, &cur_context);
 240 }
 241
 242
 243 /* Resume propagation of an FORCE_UNWIND exception, or to rethrow
 244    a normal exception that was handled.  */
 245
 246 _Unwind_Reason_Code
 247 _Unwind_Resume_or_Rethrow (struct _Unwind_Exception *exc)
 248 {
 249   struct _Unwind_Context this_context, cur_context;
 250   _Unwind_Reason_Code code;
 251
 252   /* Choose between continuing to process _Unwind_RaiseException
 253      or _Unwind_ForcedUnwind.  */
 254   if (exc->private_1 == 0)
 255     return _Unwind_RaiseException (exc);
 256
 257   uw_init_context (&this_context);
 258   cur_context = this_context;
 259
 260   code = _Unwind_ForcedUnwind_Phase2 (exc, &cur_context);
 261
 262   gcc_assert (code == _URC_INSTALL_CONTEXT);
 263
 264   uw_install_context (&this_context, &cur_context);
 265 }
 266
 267
 268 /* A convenience function that calls the exception_cleanup field.  */
 269
 270 void
 271 _Unwind_DeleteException (struct _Unwind_Exception *exc)
 272 {
 273   if (exc->exception_cleanup)
 274     (*exc->exception_cleanup) (_URC_FOREIGN_EXCEPTION_CAUGHT, exc);
 275 }
 276
 277
 278 /* Perform stack backtrace through unwind data.  */
 279
 280 _Unwind_Reason_Code
 281 _Unwind_Backtrace(_Unwind_Trace_Fn trace, void * trace_argument)
 282 {
 283   struct _Unwind_Context context;
 284   _Unwind_Reason_Code code;
 285
 286   uw_init_context (&context);
 287
 288   while (1)
 289     {
 290       _Unwind_FrameState fs;
 291
 292       /* Set up fs to describe the FDE for the caller of context.  */
 293       code = uw_frame_state_for (&context, &fs);
 294       if (code != _URC_NO_REASON && code != _URC_END_OF_STACK)
 295         return _URC_FATAL_PHASE1_ERROR;
 296
 297       /* Call trace function.  */
 298       if ((*trace) (&context, trace_argument) != _URC_NO_REASON)
 299         return _URC_FATAL_PHASE1_ERROR;
 300
 301       /* We're done at end of stack.  */
 302       if (code == _URC_END_OF_STACK)
 303         break;
 304
 305       /* Update context to describe the same frame as fs.  */
 306       uw_update_context (&context, &fs);
 307     }
 308
 309   return code;
 310 }