1 /* Exception Handling interface routines.
2 Copyright (C) 1996, 1997, 1998 Free Software Foundation, Inc.
3 Contributed by Mike Stump <mrs@cygnus.com>.
5 This file is part of GNU CC.
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)
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.
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. */
22 #if !defined(NULL_RTX) && !defined(rtx)
23 typedef struct rtx_def *_except_rtx;
24 #define rtx _except_rtx
29 /* A stack of labels. CHAIN points to the next entry in the stack. */
36 struct label_node *chain;
39 /* An eh_entry is used to describe one exception handling region.
41 OUTER_CONTEXT is the label used for rethrowing into the outer context.
43 EXCEPTION_HANDLER_LABEL is the label corresponding to the handler
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
50 FALSE_LABEL is used when either setjmp/longjmp exceptions are in
51 use, or old style table exceptions. It contains the label for
52 branching to the next runtime type check as handlers are processed.
54 FINALIZATION is the tree codes for the handler, or is NULL_TREE if
55 one hasn't been generated yet, or is integer_zero_node to mark the
56 end of a group of try blocks. */
60 rtx exception_handler_label;
65 /* If non-zero, this entry is for a handler created when we left an
66 exception-region via goto. */
67 unsigned goto_entry_p : 1;
74 /* A list of EH_ENTRYs. ENTRY is the entry; CHAIN points to the next
75 entry in the list, or is NULL if this is the last entry. */
78 struct eh_entry *entry;
79 struct eh_node *chain;
82 /* A stack of EH_ENTRYs. TOP is the topmost entry on the stack. TOP is
83 NULL if the stack is empty. */
89 /* A queue of EH_ENTRYs. HEAD is the front of the queue; TAIL is the
90 end (the latest entry). HEAD and TAIL are NULL if the queue is
98 /* Used to save exception handling status for each function. */
101 /* A stack used for keeping track of the currently active exception
102 handling region. As each exception region is started, an entry
103 describing the region is pushed onto this stack. The current
104 region can be found by looking at the top of the stack, and as we
105 exit regions, the corresponding entries are popped.
107 Entries cannot overlap; they can be nested. So there is only one
108 entry at most that corresponds to the current instruction, and that
109 is the entry on the top of the stack. */
110 struct eh_stack x_ehstack;
111 /* This stack is used to represent what the current eh region is
112 for the catch blocks beings processed */
113 struct eh_stack x_catchstack;
114 /* A queue used for tracking which exception regions have closed.
115 As we exit a region, we enqueue a new entry. The entries are then
116 dequeued during expand_leftover_cleanups and
117 expand_start_all_catch. */
118 struct eh_queue x_ehqueue;
119 /* Insns for all of the exception handlers for the current function.
120 They are currently emitted by the frontend code. */
122 /* A random data area for the front end's own use. */
123 struct label_node *x_false_label_stack;
124 /* Keeps track of the label to resume to should one want to resume
125 normal control flow out of a handler (instead of, say, returning to
126 the caller of the current function or exiting the program). */
127 struct label_node *x_caught_return_label_stack;
128 /* A TREE_CHAINed list of handlers for regions that are not yet
129 closed. The TREE_VALUE of each entry contains the handler for the
130 corresponding entry on the ehstack. */
131 union tree_node *x_protect_list;
132 /* The EH context. Nonzero if the function has already
133 fetched a pointer to the EH context for exception handling. */
135 /* The label generated by expand_builtin_eh_return. */
136 rtx x_eh_return_stub_label;
139 #define ehstack (current_function->eh->x_ehstack)
140 #define catchstack (current_function->eh->x_catchstack)
141 #define ehqueue (current_function->eh->x_ehqueue)
142 #define catch_clauses (current_function->eh->x_catch_clauses)
143 #define false_label_stack (current_function->eh->x_false_label_stack)
144 #define caught_return_label_stack (current_function->eh->x_caught_return_label_stack)
145 #define protect_list (current_function->eh->x_protect_list)
146 #define current_function_ehc (current_function->eh->ehc)
147 #define eh_return_stub_label (current_function->eh->x_eh_return_stub_label)
150 /* Start an exception handling region. All instructions emitted after
151 this point are considered to be part of the region until
152 expand_eh_region_end () is invoked. */
154 extern void expand_eh_region_start PROTO((void));
156 /* Just like expand_eh_region_start, except if a cleanup action is
157 entered on the cleanup chain, the TREE_PURPOSE of the element put
158 on the chain is DECL. DECL should be the associated VAR_DECL, if
159 any, otherwise it should be NULL_TREE. */
161 extern void expand_eh_region_start_for_decl PROTO((tree));
163 /* Start an exception handling region for the given cleanup action.
164 All instructions emitted after this point are considered to be part
165 of the region until expand_eh_region_end () is invoked. CLEANUP is
166 the cleanup action to perform. The return value is true if the
167 exception region was optimized away. If that case,
168 expand_eh_region_end does not need to be called for this cleanup,
171 This routine notices one particular common case in C++ code
172 generation, and optimizes it so as to not need the exception
175 extern int expand_eh_region_start_tree PROTO((tree, tree));
177 /* End an exception handling region. The information about the region
178 is found on the top of ehstack.
180 HANDLER is either the cleanup for the exception region, or if we're
181 marking the end of a try block, HANDLER is integer_zero_node.
183 HANDLER will be transformed to rtl when expand_leftover_cleanups ()
186 extern void expand_eh_region_end PROTO((tree));
188 /* Push RLABEL or TLABEL onto LABELSTACK. Only one of RLABEL or TLABEL
189 should be set; the other must be NULL. */
191 extern void push_label_entry PROTO((struct label_node **labelstack, rtx rlabel, tree tlabel));
193 /* Pop the topmost entry from LABELSTACK and return its value as an
194 rtx node. If LABELSTACK is empty, return NULL. */
196 extern rtx pop_label_entry PROTO((struct label_node **labelstack));
198 /* Return the topmost entry of LABELSTACK as a tree node, or return
199 NULL_TREE if LABELSTACK is empty. */
201 extern tree top_label_entry PROTO((struct label_node **labelstack));
205 /* Test: is exception handling turned on? */
207 extern int doing_eh PROTO ((int));
209 /* Toplevel initialization for EH. */
211 void set_exception_lang_code PROTO((int));
212 void set_exception_version_code PROTO((int));
214 /* A list of handlers asocciated with an exception region. HANDLER_LABEL
215 is the the label that control should be transfered to if the data
216 in TYPE_INFO matches an exception. a value of NULL_TREE for TYPE_INFO
217 means This is a cleanup, and must always be called. A value of
218 CATCH_ALL_TYPE works like a cleanup, but a call to the runtime matcher
219 is still performed to avoid being caught by a different language
220 exception. NEXT is a pointer to the next handler for this region.
221 NULL means there are no more. */
223 typedef struct handler_info
228 struct handler_info *next;
232 /* Add new handler information to an exception range. The first parameter
233 specifies the range number (returned from new_eh_entry()). The second
234 parameter specifies the handler. By default the handler is inserted at
235 the end of the list. A handler list may contain only ONE NULL_TREE
236 typeinfo entry. Regardless where it is positioned, a NULL_TREE entry
237 is always output as the LAST handler in the exception table for a region. */
239 void add_new_handler PROTO((int, struct handler_info *));
241 /* Remove a handler label. The handler label is being deleted, so all
242 regions which reference this handler should have it removed from their
243 list of possible handlers. Any region which has the final handler
244 removed can be deleted. */
246 void remove_handler PROTO((rtx));
248 /* Create a new handler structure initialized with the handler label and
249 typeinfo fields passed in. */
251 struct handler_info *get_new_handler PROTO((rtx, void *));
253 /* Make a duplicate of an exception region by copying all the handlers
254 for an exception region. Return the new handler index. */
256 int duplicate_eh_handlers PROTO((int, int, rtx (*)(rtx)));
258 /* map symbol refs for rethrow */
260 rtx rethrow_symbol_map PROTO((rtx, rtx (*)(rtx)));
262 /* Is the rethrow label for a region used? */
264 int rethrow_used PROTO((int));
266 /* Update the rethrow references to reflect rethrows which have been
269 void update_rethrow_references PROTO((void));
271 /* Get a pointer to the first handler in an exception region's list. */
273 struct handler_info *get_first_handler PROTO((int));
275 /* Find all the runtime handlers type matches currently referenced */
277 int find_all_handler_type_matches PROTO((void ***));
279 /* The eh_nesting_info structure is used to find a list of valid handlers
280 for any arbitrary exception region. When init_eh_nesting_info is called,
281 the information is all pre-calculated and entered in this structure.
282 REGION_INDEX is a vector over all possible region numbers. Since the
283 number of regions is typically much smaller than the range of block
284 numbers, this is a sparse vector and the other data structures are
285 represented as dense vectors. Indexed with an exception region number, this
286 returns the index to use in the other data structures to retreive the
288 HANDLERS is an array of vectors which point to handler_info structures.
289 when indexed, it gives the list of all possible handlers which can
290 be reached by a throw from this exception region.
291 NUM_HANDLERS is the equivilent array indicating how many handler
292 pointers there are in the HANDLERS vector.
293 OUTER_INDEX indicates which index represents the information for the
294 outer block. 0 indicates there is no outer context.
295 REGION_COUNT is the number of regions. */
297 typedef struct eh_nesting
300 handler_info ***handlers;
306 /* Initialize the eh_nesting_info structure. */
308 eh_nesting_info *init_eh_nesting_info PROTO((void));
310 /* Get a list of handlers reachable from a an exception region/insn. */
312 int reachable_handlers PROTO((int, eh_nesting_info *, rtx,
313 handler_info ***handlers));
315 /* Free the eh_nesting_info structure. */
317 void free_eh_nesting_info PROTO((eh_nesting_info *));
319 extern void init_eh PROTO((void));
321 /* Initialization for the per-function EH data. */
323 extern void init_eh_for_function PROTO((void));
325 /* Generate an exception label. Use instead of gen_label_rtx */
327 extern rtx gen_exception_label PROTO((void));
329 /* Adds an EH table entry for EH entry number N. Called from
330 final_scan_insn for NOTE_INSN_EH_REGION_BEG. */
332 extern void add_eh_table_entry PROTO((int n));
334 /* Start a catch clause, triggered by runtime value paramter. */
337 extern void start_catch_handler PROTO((tree));
340 /* End an individual catch clause. */
342 extern void end_catch_handler PROTO((void));
344 /* Returns a non-zero value if we need to output an exception table. */
346 extern int exception_table_p PROTO((void));
348 /* Outputs the exception table if we have one. */
350 extern void output_exception_table PROTO((void));
352 /* Given a return address in ADDR, determine the address we should use
353 to find the corresponding EH region. */
355 extern rtx eh_outer_context PROTO((rtx addr));
357 /* Called at the start of a block of try statements for which there is
358 a supplied catch handler. */
360 extern void expand_start_try_stmts PROTO((void));
362 /* Called at the start of a block of catch statements. It terminates the
363 previous set of try statements. */
365 extern void expand_start_all_catch PROTO((void));
367 /* Called at the end of a block of catch statements. */
369 extern void expand_end_all_catch PROTO((void));
372 /* Create a new exception region and add the handler for the region
373 onto a list. These regions will be ended (and their handlers
374 emitted) when end_protect_partials is invoked. */
376 extern void add_partial_entry PROTO((tree handler));
379 /* End all of the pending exception regions that have handlers added with
380 push_protect_entry (). */
382 extern void end_protect_partials PROTO((void));
384 /* An internal throw. */
386 extern void expand_internal_throw PROTO((void));
388 /* Called from expand_exception_blocks and expand_end_catch_block to
389 expand and pending handlers. */
391 extern void expand_leftover_cleanups PROTO((void));
393 /* If necessary, emit insns to get EH context for the current
396 extern void emit_eh_context PROTO((void));
398 /* Builds a list of handler labels and puts them in the global
399 variable exception_handler_labels. */
401 extern void find_exception_handler_labels PROTO((void));
403 /* Determine if an arbitrary label is an exception label */
405 extern int is_exception_handler_label PROTO((int));
407 /* Performs sanity checking on the check_exception_handler_labels
410 extern void check_exception_handler_labels PROTO((void));
412 /* Keeps track of the label used as the context of a throw to rethrow an
413 exception to the outer exception region. */
415 extern struct label_node *outer_context_label_stack;
417 /* A list of labels used for exception handlers. It is created by
418 find_exception_handler_labels for the optimization passes. */
420 extern rtx exception_handler_labels;
422 /* Performs optimizations for exception handling, such as removing
423 unnecessary exception regions. Invoked from jump_optimize (). */
425 extern void exception_optimize PROTO((void));
427 /* Return EH context (and set it up once per fn). */
428 extern rtx get_eh_context PROTO((void));
430 /* Get the dynamic handler chain. */
431 extern rtx get_dynamic_handler_chain PROTO((void));
433 /* Get the dynamic cleanup chain. */
434 extern rtx get_dynamic_cleanup_chain PROTO((void));
436 /* Throw an exception. */
438 extern void emit_throw PROTO((void));
440 /* One to use setjmp/longjmp method of generating code. */
442 extern int exceptions_via_longjmp;
444 /* One to enable asynchronous exception support. */
446 extern int asynchronous_exceptions;
448 /* One to protect cleanup actions with a handler that calls
449 __terminate, zero otherwise. */
451 extern int protect_cleanup_actions_with_terminate;
454 extern tree protect_with_terminate PROTO((tree));
457 extern void expand_fixup_region_start PROTO((void));
459 extern void expand_fixup_region_end PROTO((tree));
462 /* Various hooks for the DWARF 2 __throw routine. */
464 void expand_builtin_unwind_init PROTO((void));
465 rtx expand_builtin_dwarf_fp_regnum PROTO((void));
467 rtx expand_builtin_frob_return_addr PROTO((tree));
468 rtx expand_builtin_extract_return_addr PROTO((tree));
469 void expand_builtin_init_dwarf_reg_sizes PROTO((tree));
470 void expand_builtin_eh_return PROTO((tree, tree, tree));
472 void expand_eh_return PROTO((void));
475 /* Checking whether 2 instructions are within the same exception region. */
477 int in_same_eh_region PROTO((rtx, rtx));
478 void free_insn_eh_region PROTO((void));
479 void init_insn_eh_region PROTO((rtx, int));