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