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