gcc/except.h

   1 /* Exception Handling interface routines.
   2    Copyright (C) 1996, 1997 Free Software Foundation, Inc.
   3    Contributed by Mike Stump <mrs@cygnus.com>.
   4
   5 This file is part of GNU CC.
   6
   7 GNU CC 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 GNU CC 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 GNU CC; see the file COPYING.  If not, write to
  19 the Free Software Foundation, 59 Temple Place - Suite 330,
  20 Boston, MA 02111-1307, USA.  */
  21
  22 #if !defined(NULL_RTX) && !defined(rtx)
  23 typedef struct rtx_def *_except_rtx;
  24 #define rtx _except_rtx
  25 #endif
  26
  27 /* The label generated by expand_builtin_eh_return.  */
  28
  29 extern rtx eh_return_stub_label;
  30
  31 #ifdef TREE_CODE
  32
  33 /* A stack of labels. CHAIN points to the next entry in the stack.  */
  34
  35 struct label_node {
  36   union {
  37     rtx rlabel;
  38     tree tlabel;
  39   } u;
  40   struct label_node *chain;
  41 };
  42
  43 /* An eh_entry is used to describe one exception handling region.
  44
  45    OUTER_CONTEXT is the label used for rethrowing into the outer context.
  46
  47    EXCEPTION_HANDLER_LABEL is the label corresponding to the handler
  48    for this region.
  49
  50    LABEL_USED indicates whether a CATCH block has already used this
  51    label or not. New ones are needed for additional catch blocks if
  52    it has.
  53
  54    FALSE_LABEL is used when either setjmp/longjmp exceptions are in
  55    use, or old style table exceptions. It contains the label for
  56    branching to the next runtime type check as handlers are processed.
  57
  58    FINALIZATION is the tree codes for the handler, or is NULL_TREE if
  59    one hasn't been generated yet, or is integer_zero_node to mark the
  60    end of a group of try blocks.  */
  61
  62 struct eh_entry {
  63   rtx outer_context;
  64   rtx exception_handler_label;
  65   tree finalization;
  66   int label_used;
  67   rtx false_label;
  68   rtx rethrow_label;
  69 };
  70
  71 /* A list of EH_ENTRYs. ENTRY is the entry; CHAIN points to the next
  72    entry in the list, or is NULL if this is the last entry.  */
  73
  74 struct eh_node {
  75   struct eh_entry *entry;
  76   struct eh_node *chain;
  77 };
  78
  79 /* A stack of EH_ENTRYs. TOP is the topmost entry on the stack. TOP is
  80    NULL if the stack is empty.  */
  81
  82 struct eh_stack {
  83   struct eh_node *top;
  84 };
  85
  86 /* A queue of EH_ENTRYs. HEAD is the front of the queue; TAIL is the
  87    end (the latest entry). HEAD and TAIL are NULL if the queue is
  88    empty.  */
  89
  90 struct eh_queue {
  91   struct eh_node *head;
  92   struct eh_node *tail;
  93 };
  94
  95 /* Start an exception handling region.  All instructions emitted after
  96    this point are considered to be part of the region until
  97    expand_eh_region_end () is invoked.  */
  98
  99 extern void expand_eh_region_start              PROTO((void));
 100
 101 /* Just like expand_eh_region_start, except if a cleanup action is
 102    entered on the cleanup chain, the TREE_PURPOSE of the element put
 103    on the chain is DECL.  DECL should be the associated VAR_DECL, if
 104    any, otherwise it should be NULL_TREE.  */
 105
 106 extern void expand_eh_region_start_for_decl     PROTO((tree));
 107
 108 /* Start an exception handling region for the given cleanup action.
 109    All instructions emitted after this point are considered to be part
 110    of the region until expand_eh_region_end () is invoked.  CLEANUP is
 111    the cleanup action to perform.  The return value is true if the
 112    exception region was optimized away.  If that case,
 113    expand_eh_region_end does not need to be called for this cleanup,
 114    nor should it be.
 115
 116    This routine notices one particular common case in C++ code
 117    generation, and optimizes it so as to not need the exception
 118    region.  */
 119
 120 extern int expand_eh_region_start_tree          PROTO((tree, tree));
 121
 122 /* End an exception handling region.  The information about the region
 123    is found on the top of ehstack.
 124
 125    HANDLER is either the cleanup for the exception region, or if we're
 126    marking the end of a try block, HANDLER is integer_zero_node.
 127
 128    HANDLER will be transformed to rtl when expand_leftover_cleanups ()
 129    is invoked.  */
 130
 131 extern void expand_eh_region_end                PROTO((tree));
 132
 133 /* Push RLABEL or TLABEL onto LABELSTACK. Only one of RLABEL or TLABEL
 134    should be set; the other must be NULL.  */
 135
 136 extern void push_label_entry                    PROTO((struct label_node **labelstack, rtx rlabel, tree tlabel));
 137
 138 /* Pop the topmost entry from LABELSTACK and return its value as an
 139    rtx node. If LABELSTACK is empty, return NULL.  */
 140
 141 extern rtx pop_label_entry                      PROTO((struct label_node **labelstack));
 142
 143 /* Return the topmost entry of LABELSTACK as a tree node, or return
 144    NULL_TREE if LABELSTACK is empty.  */
 145
 146 extern tree top_label_entry                     PROTO((struct label_node **labelstack));
 147
 148 /* A set of insns for the catch clauses in the current function. They
 149    will be emitted at the end of the current function.  */
 150
 151 extern rtx catch_clauses;
 152
 153 #endif
 154
 155 /* Test: is exception handling turned on? */
 156
 157 extern int doing_eh                                    PROTO ((int));
 158
 159 /* Toplevel initialization for EH.  */
 160
 161 void set_exception_lang_code                    PROTO((int));
 162 void set_exception_version_code                 PROTO((int));
 163
 164 /* A list of handlers asocciated with an exception region. HANDLER_LABEL
 165    is the the label that control should be transfered to if the data
 166    in TYPE_INFO matches an exception. a value of NULL_TREE for TYPE_INFO
 167    means This is a cleanup, and must always be called. A value of
 168    CATCH_ALL_TYPE works like a cleanup, but a call to the runtime matcher
 169    is still performed to avoid being caught by a different language
 170    exception. NEXT is a pointer to the next handler for this region.
 171    NULL means there are no more. */
 172
 173 typedef struct handler_info
 174 {
 175   rtx handler_label;
 176   int handler_number;
 177   void *type_info;
 178   struct handler_info *next;
 179 } handler_info;
 180
 181
 182 /* Add new handler information to an exception range. The  first parameter
 183    specifies the range number (returned from new_eh_entry()). The second
 184    parameter specifies the handler.  By default the handler is inserted at
 185    the end of the list. A handler list may contain only ONE NULL_TREE
 186    typeinfo entry. Regardless where it is positioned, a NULL_TREE entry
 187    is always output as the LAST handler in the exception table for a region. */
 188
 189 void add_new_handler                       PROTO((int, struct handler_info *));
 190
 191 /* Remove a handler label. The handler label is being deleted, so all
 192    regions which reference this handler should have it removed from their
 193    list of possible handlers. Any region which has the final handler
 194    removed can be deleted. */
 195
 196 void remove_handler                        PROTO((rtx));
 197
 198 /* Create a new handler structure initialized with the handler label and
 199    typeinfo fields passed in. */
 200
 201 struct handler_info *get_new_handler            PROTO((rtx, void *));
 202
 203 /* Make a duplicate of an exception region by copying all the handlers
 204    for an exception region. Return the new handler index. */
 205
 206 int duplicate_eh_handlers                       PROTO((int, int, rtx (*)(rtx)));
 207
 208 /* map symbol refs for rethrow */
 209
 210 rtx rethrow_symbol_map                          PROTO((rtx, rtx (*)(rtx)));
 211
 212 /* Is the rethrow label for a region used? */
 213
 214 int rethrow_used                                PROTO((int));
 215
 216 /* Return the region number a this is the rethrow label for. */
 217
 218 int eh_region_from_symbol                       PROTO((rtx));
 219
 220 /* Get a pointer to the first handler in an exception region's list. */
 221
 222 struct handler_info *get_first_handler          PROTO((int));
 223
 224 /* Find all the runtime handlers type matches currently referenced */
 225
 226 int find_all_handler_type_matches               PROTO((void ***));
 227
 228 extern void init_eh                             PROTO((void));
 229
 230 /* Initialization for the per-function EH data.  */
 231
 232 extern void init_eh_for_function                PROTO((void));
 233
 234 /* Generate an exception label. Use instead of gen_label_rtx */
 235
 236 extern rtx gen_exception_label                  PROTO((void));
 237
 238 /* Adds an EH table entry for EH entry number N. Called from
 239    final_scan_insn for NOTE_INSN_EH_REGION_BEG.  */
 240
 241 extern void add_eh_table_entry                  PROTO((int n));
 242
 243 /* Start a catch clause, triggered by runtime value paramter. */
 244
 245 #ifdef TREE_CODE
 246 extern void start_catch_handler                 PROTO((tree));
 247 #endif
 248
 249 /* End an individual catch clause. */
 250
 251 extern void end_catch_handler                   PROTO((void));
 252
 253 /* Returns a non-zero value if we need to output an exception table.  */
 254
 255 extern int exception_table_p                    PROTO((void));
 256
 257 /* Outputs the exception table if we have one.  */
 258
 259 extern void output_exception_table              PROTO((void));
 260
 261 /* Given a return address in ADDR, determine the address we should use
 262    to find the corresponding EH region.  */
 263
 264 extern rtx eh_outer_context                     PROTO((rtx addr));
 265
 266 /* Called at the start of a block of try statements for which there is
 267    a supplied catch handler.  */
 268
 269 extern void expand_start_try_stmts              PROTO((void));
 270
 271 /* Called at the start of a block of catch statements. It terminates the
 272    previous set of try statements.  */
 273
 274 extern void expand_start_all_catch              PROTO((void));
 275
 276 /* Called at the end of a block of catch statements.  */
 277
 278 extern void expand_end_all_catch                PROTO((void));
 279
 280 #ifdef TREE_CODE
 281 /* Create a new exception region and add the handler for the region
 282    onto a list. These regions will be ended (and their handlers
 283    emitted) when end_protect_partials is invoked.  */
 284
 285 extern void add_partial_entry                   PROTO((tree handler));
 286 #endif
 287
 288 /* End all of the pending exception regions that have handlers added with
 289    push_protect_entry ().  */
 290
 291 extern void end_protect_partials                PROTO((void));
 292
 293 /* An internal throw.  */
 294
 295 extern void expand_internal_throw               PROTO((void));
 296
 297 /* Called from expand_exception_blocks and expand_end_catch_block to
 298    expand and pending handlers.  */
 299
 300 extern void expand_leftover_cleanups            PROTO((void));
 301
 302 /* If necessary, emit insns to get EH context for the current
 303    function. */
 304
 305 extern void emit_eh_context                     PROTO((void));
 306
 307 /* Builds a list of handler labels and puts them in the global
 308    variable exception_handler_labels.  */
 309
 310 extern void find_exception_handler_labels       PROTO((void));
 311
 312 /* Determine if an arbitrary label is an exception label */
 313
 314 extern int is_exception_handler_label           PROTO((int));
 315
 316 /* Performs sanity checking on the check_exception_handler_labels
 317    list.  */
 318
 319 extern void check_exception_handler_labels      PROTO((void));
 320
 321 /* A stack used to keep track of the label used to resume normal program
 322    flow out of the current exception handler region.  */
 323
 324 extern struct label_node *caught_return_label_stack;
 325
 326 /* Keeps track of the label used as the context of a throw to rethrow an
 327    exception to the outer exception region.  */
 328
 329 extern struct label_node *outer_context_label_stack;
 330
 331 /* A random area used for purposes elsewhere.  */
 332
 333 extern struct label_node *false_label_stack;
 334
 335 /* A list of labels used for exception handlers. It is created by
 336    find_exception_handler_labels for the optimization passes.  */
 337
 338 extern rtx exception_handler_labels;
 339
 340 /* Performs optimizations for exception handling, such as removing
 341    unnecessary exception regions. Invoked from jump_optimize ().  */
 342
 343 extern void exception_optimize                  PROTO((void));
 344
 345 /* Return EH context (and set it up once per fn).  */
 346 extern rtx get_eh_context                       PROTO((void));
 347
 348 /* Get the dynamic handler chain.  */
 349 extern rtx get_dynamic_handler_chain            PROTO((void));
 350
 351 /* Get the dynamic cleanup chain.  */
 352 extern rtx get_dynamic_cleanup_chain            PROTO((void));
 353
 354 /* Throw an exception.  */
 355
 356 extern void emit_throw                          PROTO((void));
 357
 358 /* One to use setjmp/longjmp method of generating code.  */
 359
 360 extern int exceptions_via_longjmp;
 361
 362 /* One to enable asynchronous exception support.  */
 363
 364 extern int asynchronous_exceptions;
 365
 366 /* One to protect cleanup actions with a handler that calls
 367    __terminate, zero otherwise.  */
 368
 369 extern int protect_cleanup_actions_with_terminate;
 370
 371 #ifdef TREE_CODE
 372 extern tree protect_with_terminate              PROTO((tree));
 373 #endif
 374
 375 extern void expand_fixup_region_start   PROTO((void));
 376 #ifdef TREE_CODE
 377 extern void expand_fixup_region_end     PROTO((tree));
 378 #endif
 379
 380 /* Various hooks for the DWARF 2 __throw routine.  */
 381
 382 void expand_builtin_unwind_init         PROTO((void));
 383 rtx expand_builtin_dwarf_fp_regnum      PROTO((void));
 384 #ifdef TREE_CODE
 385 rtx expand_builtin_frob_return_addr     PROTO((tree));
 386 rtx expand_builtin_extract_return_addr  PROTO((tree));
 387 rtx expand_builtin_dwarf_reg_size       PROTO((tree, rtx));
 388 void expand_builtin_eh_return           PROTO((tree, tree, tree));
 389 #endif
 390 void expand_eh_return                   PROTO((void));
 391
 392
 393 /* Checking whether 2 instructions are within the same exception region. */
 394
 395 int in_same_eh_region                   PROTO((rtx, rtx));
 396 void free_insn_eh_region                PROTO((void));
 397 void init_insn_eh_region                PROTO((rtx, int));
 398
 399 #ifdef rtx
 400 #undef rtx
 401 #endif