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, and discard
 188          the previous context if necessary.  */
 189       uw_advance_context (context, &fs);
 190     }
 191
 192   return code;
 193 }
 194
 195
 196 /* Raise an exception for forced unwinding.  */
 197
 198 _Unwind_Reason_Code
 199 _Unwind_ForcedUnwind (struct _Unwind_Exception *exc,
 200                       _Unwind_Stop_Fn stop, void * stop_argument)
 201 {
 202   struct _Unwind_Context this_context, cur_context;
 203   _Unwind_Reason_Code code;
 204
 205   uw_init_context (&this_context);
 206   cur_context = this_context;
 207
 208   exc->private_1 = (_Unwind_Ptr) stop;
 209   exc->private_2 = (_Unwind_Ptr) stop_argument;
 210
 211   code = _Unwind_ForcedUnwind_Phase2 (exc, &cur_context);
 212   if (code != _URC_INSTALL_CONTEXT)
 213     return code;
 214
 215   uw_install_context (&this_context, &cur_context);
 216 }
 217
 218
 219 /* Resume propagation of an existing exception.  This is used after
 220    e.g. executing cleanup code, and not to implement rethrowing.  */
 221
 222 void
 223 _Unwind_Resume (struct _Unwind_Exception *exc)
 224 {
 225   struct _Unwind_Context this_context, cur_context;
 226   _Unwind_Reason_Code code;
 227
 228   uw_init_context (&this_context);
 229   cur_context = this_context;
 230
 231   /* Choose between continuing to process _Unwind_RaiseException
 232      or _Unwind_ForcedUnwind.  */
 233   if (exc->private_1 == 0)
 234     code = _Unwind_RaiseException_Phase2 (exc, &cur_context);
 235   else
 236     code = _Unwind_ForcedUnwind_Phase2 (exc, &cur_context);
 237
 238   gcc_assert (code == _URC_INSTALL_CONTEXT);
 239
 240   uw_install_context (&this_context, &cur_context);
 241 }
 242
 243
 244 /* Resume propagation of an FORCE_UNWIND exception, or to rethrow
 245    a normal exception that was handled.  */
 246
 247 _Unwind_Reason_Code
 248 _Unwind_Resume_or_Rethrow (struct _Unwind_Exception *exc)
 249 {
 250   struct _Unwind_Context this_context, cur_context;
 251   _Unwind_Reason_Code code;
 252
 253   /* Choose between continuing to process _Unwind_RaiseException
 254      or _Unwind_ForcedUnwind.  */
 255   if (exc->private_1 == 0)
 256     return _Unwind_RaiseException (exc);
 257
 258   uw_init_context (&this_context);
 259   cur_context = this_context;
 260
 261   code = _Unwind_ForcedUnwind_Phase2 (exc, &cur_context);
 262
 263   gcc_assert (code == _URC_INSTALL_CONTEXT);
 264
 265   uw_install_context (&this_context, &cur_context);
 266 }
 267
 268
 269 /* A convenience function that calls the exception_cleanup field.  */
 270
 271 void
 272 _Unwind_DeleteException (struct _Unwind_Exception *exc)
 273 {
 274   if (exc->exception_cleanup)
 275     (*exc->exception_cleanup) (_URC_FOREIGN_EXCEPTION_CAUGHT, exc);
 276 }
 277
 278
 279 /* Perform stack backtrace through unwind data.  */
 280
 281 _Unwind_Reason_Code
 282 _Unwind_Backtrace(_Unwind_Trace_Fn trace, void * trace_argument)
 283 {
 284   struct _Unwind_Context context;
 285   _Unwind_Reason_Code code;
 286
 287   uw_init_context (&context);
 288
 289   while (1)
 290     {
 291       _Unwind_FrameState fs;
 292
 293       /* Set up fs to describe the FDE for the caller of context.  */
 294       code = uw_frame_state_for (&context, &fs);
 295       if (code != _URC_NO_REASON && code != _URC_END_OF_STACK)
 296         return _URC_FATAL_PHASE1_ERROR;
 297
 298       /* Call trace function.  */
 299       if ((*trace) (&context, trace_argument) != _URC_NO_REASON)
 300         return _URC_FATAL_PHASE1_ERROR;
 301
 302       /* We're done at end of stack.  */
 303       if (code == _URC_END_OF_STACK)
 304         break;
 305
 306       /* Update context to describe the same frame as fs.  */
 307       uw_update_context (&context, &fs);
 308     }
 309
 310   return code;
 311 }