gcc/except.h

   1 /* Exception Handling interface routines.
   2    Copyright (C) 1996 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
  23 #ifndef GET_CODE
  24 #define rtx int *
  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    FINALIZATION is the tree codes for the handler, or is NULL_TREE if
  47    one hasn't been generated yet, or is integer_zero_node to mark the
  48    end of a group of try blocks.  */
  49
  50 struct eh_entry {
  51   rtx outer_context;
  52   rtx exception_handler_label;
  53
  54   tree finalization;
  55 };
  56
  57 /* A list of EH_ENTRYs. ENTRY is the entry; CHAIN points to the next
  58    entry in the list, or is NULL if this is the last entry.  */
  59
  60 struct eh_node {
  61   struct eh_entry *entry;
  62   struct eh_node *chain;
  63 };
  64
  65 /* A stack of EH_ENTRYs. TOP is the topmost entry on the stack. TOP is
  66    NULL if the stack is empty.  */
  67
  68 struct eh_stack {
  69   struct eh_node *top;
  70 };
  71
  72 /* A queue of EH_ENTRYs. HEAD is the front of the queue; TAIL is the
  73    end (the latest entry). HEAD and TAIL are NULL if the queue is
  74    empty.  */
  75
  76 struct eh_queue {
  77   struct eh_node *head;
  78   struct eh_node *tail;
  79 };
  80
  81
  82 /* Start an exception handling region.  All instructions emitted after
  83    this point are considered to be part of the region until
  84    expand_eh_region_end () is invoked.  */
  85
  86 extern void expand_eh_region_start              PROTO((void));
  87
  88 /* Just like expand_eh_region_start, except if a cleanup action is
  89    entered on the cleanup chain, the TREE_PURPOSE of the element put
  90    on the chain is DECL.  DECL should be the associated VAR_DECL, if
  91    any, otherwise it should be NULL_TREE.  */
  92
  93 extern void expand_eh_region_start_for_decl     PROTO((tree));
  94
  95 /* Start an exception handling region for the given cleanup action.
  96    All instructions emitted after this point are considered to be part
  97    of the region until expand_eh_region_end () is invoked.  CLEANUP is
  98    the cleanup action to perform.  The return value is true if the
  99    exception region was optimized away.  If that case,
 100    expand_eh_region_end does not need to be called for this cleanup,
 101    nor should it be.
 102
 103    This routine notices one particular common case in C++ code
 104    generation, and optimizes it so as to not need the exception
 105    region.  */
 106
 107 extern int expand_eh_region_start_tree          PROTO((tree, tree));
 108
 109 /* End an exception handling region.  The information about the region
 110    is found on the top of ehstack.
 111
 112    HANDLER is either the cleanup for the exception region, or if we're
 113    marking the end of a try block, HANDLER is integer_zero_node.
 114
 115    HANDLER will be transformed to rtl when expand_leftover_cleanups ()
 116    is invoked.  */
 117
 118 extern void expand_eh_region_end                PROTO((tree));
 119
 120 /* Push RLABEL or TLABEL onto LABELSTACK. Only one of RLABEL or TLABEL
 121    should be set; the other must be NULL.  */
 122
 123 extern void push_label_entry                    PROTO((struct label_node **labelstack, rtx rlabel, tree tlabel));
 124
 125 /* Pop the topmost entry from LABELSTACK and return its value as an
 126    rtx node. If LABELSTACK is empty, return NULL.  */
 127
 128 extern rtx pop_label_entry                      PROTO((struct label_node **labelstack));
 129
 130 /* Return the topmost entry of LABELSTACK as a tree node, or return
 131    NULL_TREE if LABELSTACK is empty.  */
 132
 133 extern tree top_label_entry                     PROTO((struct label_node **labelstack));
 134
 135 /* A set of insns for the catch clauses in the current function. They
 136    will be emitted at the end of the current function.  */
 137
 138 extern rtx catch_clauses;
 139
 140 #endif
 141
 142 struct function;
 143
 144 /* Toplevel initialization for EH.  */
 145
 146 extern void init_eh                             PROTO((void));
 147
 148 /* Initialization for the per-function EH data.  */
 149
 150 extern void init_eh_for_function                PROTO((void));
 151
 152 /* Saves the current per-function EH data into P.  */
 153
 154 extern void save_eh_status                      PROTO((struct function *p));
 155
 156 /* Restores the per-function EH data from P.  */
 157
 158 extern void restore_eh_status                   PROTO((struct function *p));
 159
 160 /* Adds an EH table entry for EH entry number N. Called from
 161    final_scan_insn for NOTE_INSN_EH_REGION_BEG.  */
 162
 163 extern void add_eh_table_entry                  PROTO((int n));
 164
 165 /* Returns a non-zero value if we need to output an exception table.  */
 166
 167 extern int exception_table_p                    PROTO((void));
 168
 169 /* Outputs the exception table if we have one.  */
 170
 171 extern void output_exception_table              PROTO((void));
 172
 173 /* Given a return address in ADDR, determine the address we should use
 174    to find the corresponding EH region.  */
 175
 176 extern rtx eh_outer_context                     PROTO((rtx addr));
 177
 178 /* Called at the start of a block of try statements for which there is
 179    a supplied catch handler.  */
 180
 181 extern void expand_start_try_stmts              PROTO((void));
 182
 183 /* Called at the start of a block of catch statements. It terminates the
 184    previous set of try statements.  */
 185
 186 extern void expand_start_all_catch              PROTO((void));
 187
 188 /* Called at the end of a block of catch statements.  */
 189
 190 extern void expand_end_all_catch                PROTO((void));
 191
 192 #ifdef TREE_CODE
 193 /* Create a new exception region and add the handler for the region
 194    onto a list. These regions will be ended (and their handlers
 195    emitted) when end_protect_partials is invoked.  */
 196
 197 extern void add_partial_entry                   PROTO((tree handler));
 198 #endif
 199
 200 /* End all of the pending exception regions that have handlers added with
 201    push_protect_entry ().  */
 202
 203 extern void end_protect_partials                PROTO((void));
 204
 205 /* An internal throw with a direct CONTEXT we want to throw
 206    from. CONTEXT must be a label.  */
 207
 208 extern void expand_internal_throw               PROTO((rtx context));
 209
 210 /* Called from expand_exception_blocks and expand_end_catch_block to
 211    expand and pending handlers.  */
 212
 213 extern void expand_leftover_cleanups            PROTO((void));
 214
 215 /* If necessary, emit insns for the start of per-function unwinder for
 216    the current function.  */
 217
 218 extern void emit_unwinder                       PROTO((void));
 219
 220 /* If necessary, emit insns for the end of the per-function unwinder
 221    for the current function.  */
 222
 223 extern void end_eh_unwinder                     PROTO((void));
 224
 225 /* Builds a list of handler labels and puts them in the global
 226    variable exception_handler_labels.  */
 227
 228 extern void find_exception_handler_labels       PROTO((void));
 229
 230 /* Performs sanity checking on the check_exception_handler_labels
 231    list.  */
 232
 233 extern void check_exception_handler_labels      PROTO((void));
 234
 235 /* A stack used to keep track of the label used to resume normal program
 236    flow out of the current exception handler region.  */
 237
 238 extern struct label_node *caught_return_label_stack;
 239
 240 /* A random area used for purposes elsewhere.  */
 241
 242 extern struct label_node *false_label_stack;
 243
 244 /* A list of labels used for exception handlers. It is created by
 245    find_exception_handler_labels for the optimization passes.  */
 246
 247 extern rtx exception_handler_labels;
 248
 249 /* The rtx for the saved PC value.  */
 250
 251 extern rtx eh_saved_pc_rtx;
 252
 253 /* Performs optimizations for exception handling, such as removing
 254    unnecessary exception regions. Invoked from jump_optimize ().  */
 255
 256 extern void exception_optimize                  PROTO((void));
 257
 258 /* Get the dynamic handler chain.  */
 259 extern rtx get_dynamic_handler_chain            PROTO((void));
 260
 261 /* Get the dynamic cleanup chain.  */
 262 extern rtx get_dynamic_cleanup_chain            PROTO((void));
 263
 264 /* Throw an exception.  */
 265
 266 extern void emit_throw                          PROTO((void));
 267
 268 /* One to use setjmp/longjmp method of generating code.  */
 269
 270 extern int exceptions_via_longjmp;
 271
 272 /* One to enable asynchronous exception support.  */
 273
 274 extern int asynchronous_exceptions;
 275
 276 /* One to protect cleanup actions with a handler that calls
 277    __terminate, zero otherwise.  */
 278
 279 extern int protect_cleanup_actions_with_terminate;
 280
 281 #ifdef TREE_CODE
 282 extern tree protect_with_terminate              PROTO((tree));
 283 #endif