1 /* Exception Handling interface routines.
2 Copyright (C) 1996, 97-99, 2000 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
96 struct eh_queue *next;
99 /* Used to save exception handling status for each function. */
102 /* A stack used for keeping track of the currently active exception
103 handling region. As each exception region is started, an entry
104 describing the region is pushed onto this stack. The current
105 region can be found by looking at the top of the stack, and as we
106 exit regions, the corresponding entries are popped.
108 Entries cannot overlap; they can be nested. So there is only one
109 entry at most that corresponds to the current instruction, and that
110 is the entry on the top of the stack. */
111 struct eh_stack x_ehstack;
112 /* This stack is used to represent what the current eh region is
113 for the catch blocks beings processed */
114 struct eh_stack x_catchstack;
115 /* A queue used for tracking which exception regions have closed.
116 As we exit a region, we enqueue a new entry. The entries are then
117 dequeued during expand_leftover_cleanups and
118 expand_start_all_catch. */
119 struct eh_queue *x_ehqueue;
120 /* Insns for all of the exception handlers for the current function.
121 They are currently emitted by the frontend code. */
123 /* A random data area for the front end's own use. */
124 struct label_node *x_false_label_stack;
125 /* Keeps track of the label to resume to should one want to resume
126 normal control flow out of a handler (instead of, say, returning to
127 the caller of the current function or exiting the program). */
128 struct label_node *x_caught_return_label_stack;
129 /* A stack (TREE_LIST) of lists of handlers. The TREE_VALUE of each
130 node is itself a TREE_CHAINed list of handlers for regions that
131 are not yet closed. The TREE_VALUE of each entry contains the
132 handler for the corresponding entry on the ehstack. */
133 union tree_node *x_protect_list;
134 /* The EH context. Nonzero if the function has already
135 fetched a pointer to the EH context for exception handling. */
137 /* The label generated by expand_builtin_eh_return. */
138 rtx x_eh_return_stub_label;
141 #define ehstack (cfun->eh->x_ehstack)
142 #define catchstack (cfun->eh->x_catchstack)
143 #define ehqueue (cfun->eh->x_ehqueue)
144 #define catch_clauses (cfun->eh->x_catch_clauses)
145 #define false_label_stack (cfun->eh->x_false_label_stack)
146 #define caught_return_label_stack (cfun->eh->x_caught_return_label_stack)
147 #define protect_list (cfun->eh->x_protect_list)
148 #define current_function_ehc (cfun->eh->ehc)
149 #define eh_return_stub_label (cfun->eh->x_eh_return_stub_label)
152 /* Start an exception handling region. All instructions emitted after
153 this point are considered to be part of the region until
154 expand_eh_region_end () is invoked. */
156 extern void expand_eh_region_start PARAMS ((void));
158 /* Just like expand_eh_region_start, except if a cleanup action is
159 entered on the cleanup chain, the TREE_PURPOSE of the element put
160 on the chain is DECL. DECL should be the associated VAR_DECL, if
161 any, otherwise it should be NULL_TREE. */
163 extern void expand_eh_region_start_for_decl PARAMS ((tree));
165 /* Start an exception handling region for the given cleanup action.
166 All instructions emitted after this point are considered to be part
167 of the region until expand_eh_region_end () is invoked. CLEANUP is
168 the cleanup action to perform. The return value is true if the
169 exception region was optimized away. If that case,
170 expand_eh_region_end does not need to be called for this cleanup,
173 This routine notices one particular common case in C++ code
174 generation, and optimizes it so as to not need the exception
177 extern int expand_eh_region_start_tree PARAMS ((tree, tree));
179 /* End an exception handling region. The information about the region
180 is found on the top of ehstack.
182 HANDLER is either the cleanup for the exception region, or if we're
183 marking the end of a try block, HANDLER is integer_zero_node.
185 HANDLER will be transformed to rtl when expand_leftover_cleanups ()
188 extern void expand_eh_region_end PARAMS ((tree));
190 /* Push RLABEL or TLABEL onto LABELSTACK. Only one of RLABEL or TLABEL
191 should be set; the other must be NULL. */
193 extern void push_label_entry PARAMS ((struct label_node **labelstack,
194 rtx rlabel, tree tlabel));
196 /* Pop the topmost entry from LABELSTACK and return its value as an
197 rtx node. If LABELSTACK is empty, return NULL. */
199 extern rtx pop_label_entry PARAMS ((struct label_node **labelstack));
201 /* Return the topmost entry of LABELSTACK as a tree node, or return
202 NULL_TREE if LABELSTACK is empty. */
204 extern tree top_label_entry PARAMS ((struct label_node **labelstack));
208 /* Test: is exception handling turned on? */
210 extern int doing_eh PARAMS ((int));
212 /* Toplevel initialization for EH. */
214 void set_exception_lang_code PARAMS ((int));
215 void set_exception_version_code PARAMS ((int));
217 /* A list of handlers asocciated with an exception region. HANDLER_LABEL
218 is the the label that control should be transfered to if the data
219 in TYPE_INFO matches an exception. a value of NULL_TREE for TYPE_INFO
220 means This is a cleanup, and must always be called. A value of
221 CATCH_ALL_TYPE works like a cleanup, but a call to the runtime matcher
222 is still performed to avoid being caught by a different language
223 exception. NEXT is a pointer to the next handler for this region.
224 NULL means there are no more. */
226 typedef struct handler_info
231 struct handler_info *next;
235 /* Add new handler information to an exception range. The first parameter
236 specifies the range number (returned from new_eh_entry()). The second
237 parameter specifies the handler. By default the handler is inserted at
238 the end of the list. A handler list may contain only ONE NULL_TREE
239 typeinfo entry. Regardless where it is positioned, a NULL_TREE entry
240 is always output as the LAST handler in the exception table for a region. */
242 void add_new_handler PARAMS ((int, struct handler_info *));
244 /* Remove a handler label. The handler label is being deleted, so all
245 regions which reference this handler should have it removed from their
246 list of possible handlers. Any region which has the final handler
247 removed can be deleted. */
249 void remove_handler PARAMS ((rtx));
251 /* Create a new handler structure initialized with the handler label and
252 typeinfo fields passed in. */
254 struct handler_info *get_new_handler PARAMS ((rtx, void *));
256 /* Make a duplicate of an exception region by copying all the handlers
257 for an exception region. Return the new handler index. */
259 int duplicate_eh_handlers PARAMS ((int, int, rtx (*)(rtx)));
261 /* map symbol refs for rethrow */
263 rtx rethrow_symbol_map PARAMS ((rtx, rtx (*)(rtx)));
265 /* Is the rethrow label for a region used? */
267 int rethrow_used PARAMS ((int));
269 /* Update the rethrow references to reflect rethrows which have been
272 void update_rethrow_references PARAMS ((void));
274 /* Get a pointer to the first handler in an exception region's list. */
276 struct handler_info *get_first_handler PARAMS ((int));
278 /* Find all the runtime handlers type matches currently referenced */
280 int find_all_handler_type_matches PARAMS ((void ***));
282 /* The eh_nesting_info structure is used to find a list of valid handlers
283 for any arbitrary exception region. When init_eh_nesting_info is called,
284 the information is all pre-calculated and entered in this structure.
285 REGION_INDEX is a vector over all possible region numbers. Since the
286 number of regions is typically much smaller than the range of block
287 numbers, this is a sparse vector and the other data structures are
288 represented as dense vectors. Indexed with an exception region number, this
289 returns the index to use in the other data structures to retreive the
291 HANDLERS is an array of vectors which point to handler_info structures.
292 when indexed, it gives the list of all possible handlers which can
293 be reached by a throw from this exception region.
294 NUM_HANDLERS is the equivilent array indicating how many handler
295 pointers there are in the HANDLERS vector.
296 OUTER_INDEX indicates which index represents the information for the
297 outer block. 0 indicates there is no outer context.
298 REGION_COUNT is the number of regions. */
300 typedef struct eh_nesting
303 handler_info ***handlers;
309 /* Initialize the eh_nesting_info structure. */
311 eh_nesting_info *init_eh_nesting_info PARAMS ((void));
313 /* Get a list of handlers reachable from a an exception region/insn. */
315 int reachable_handlers PARAMS ((int, eh_nesting_info *, rtx,
316 handler_info ***handlers));
318 /* Free the eh_nesting_info structure. */
320 void free_eh_nesting_info PARAMS ((eh_nesting_info *));
322 extern void init_eh PARAMS ((void));
324 /* Initialization for the per-function EH data. */
326 extern void init_eh_for_function PARAMS ((void));
328 /* Generate an exception label. Use instead of gen_label_rtx */
330 extern rtx gen_exception_label PARAMS ((void));
332 /* Adds an EH table entry for EH entry number N. Called from
333 final_scan_insn for NOTE_INSN_EH_REGION_BEG. */
335 extern void add_eh_table_entry PARAMS ((int n));
337 /* Start a catch clause, triggered by runtime value paramter. */
340 extern void start_catch_handler PARAMS ((tree));
343 /* End an individual catch clause. */
345 extern void end_catch_handler PARAMS ((void));
347 /* Returns a non-zero value if we need to output an exception table. */
349 extern int exception_table_p PARAMS ((void));
351 /* Outputs the exception table if we have one. */
353 extern void output_exception_table PARAMS ((void));
355 /* Given a return address in ADDR, determine the address we should use
356 to find the corresponding EH region. */
358 extern rtx eh_outer_context PARAMS ((rtx addr));
360 /* Called at the start of a block of try statements for which there is
361 a supplied catch handler. */
363 extern void expand_start_try_stmts PARAMS ((void));
365 /* Called at the start of a block of catch statements. It terminates the
366 previous set of try statements. */
368 extern void expand_start_all_catch PARAMS ((void));
370 /* Called at the end of a block of catch statements. */
372 extern void expand_end_all_catch PARAMS ((void));
374 /* Begin a region that will contain entries created with
375 add_partial_entry. */
377 extern void begin_protect_partials PARAMS ((void));
380 /* Create a new exception region and add the handler for the region
381 onto a list. These regions will be ended (and their handlers
382 emitted) when end_protect_partials is invoked. */
384 extern void add_partial_entry PARAMS ((tree handler));
387 /* End all of the pending exception regions that have handlers added with
388 push_protect_entry (). */
390 extern void end_protect_partials PARAMS ((void));
392 /* An internal throw. */
394 extern void expand_internal_throw PARAMS ((void));
396 /* Called from expand_exception_blocks and expand_end_catch_block to
397 expand and pending handlers. */
399 extern void expand_leftover_cleanups PARAMS ((void));
401 /* If necessary, emit insns to get EH context for the current
404 extern void emit_eh_context PARAMS ((void));
406 /* Builds a list of handler labels and puts them in the global
407 variable exception_handler_labels. */
409 extern void find_exception_handler_labels PARAMS ((void));
411 /* Determine if an arbitrary label is an exception label */
413 extern int is_exception_handler_label PARAMS ((int));
415 /* Performs sanity checking on the check_exception_handler_labels
418 extern void check_exception_handler_labels PARAMS ((void));
420 /* Keeps track of the label used as the context of a throw to rethrow an
421 exception to the outer exception region. */
423 extern struct label_node *outer_context_label_stack;
425 /* A list of labels used for exception handlers. It is created by
426 find_exception_handler_labels for the optimization passes. */
428 extern rtx exception_handler_labels;
430 /* Performs optimizations for exception handling, such as removing
431 unnecessary exception regions. Invoked from jump_optimize (). */
433 extern void exception_optimize PARAMS ((void));
435 /* Return EH context (and set it up once per fn). */
436 extern rtx get_eh_context PARAMS ((void));
438 /* Get the dynamic handler chain. */
439 extern rtx get_dynamic_handler_chain PARAMS ((void));
441 /* Get the dynamic cleanup chain. */
442 extern rtx get_dynamic_cleanup_chain PARAMS ((void));
444 /* Throw an exception. */
446 extern void emit_throw PARAMS ((void));
448 /* Save away the current ehqueue. */
449 extern void push_ehqueue PARAMS ((void));
451 /* Restore a previously pushed ehqueue. */
452 extern void pop_ehqueue PARAMS ((void));
454 /* One to use setjmp/longjmp method of generating code. */
456 extern int exceptions_via_longjmp;
458 /* One to enable asynchronous exception support. */
460 extern int asynchronous_exceptions;
462 /* One to protect cleanup actions with a handler that calls
463 __terminate, zero otherwise. */
465 extern int protect_cleanup_actions_with_terminate;
468 extern tree protect_with_terminate PARAMS ((tree));
471 extern void expand_fixup_region_start PARAMS ((void));
473 extern void expand_fixup_region_end PARAMS ((tree));
476 /* Various hooks for the DWARF 2 __throw routine. */
478 void expand_builtin_unwind_init PARAMS ((void));
479 rtx expand_builtin_dwarf_fp_regnum PARAMS ((void));
481 rtx expand_builtin_frob_return_addr PARAMS ((tree));
482 rtx expand_builtin_extract_return_addr PARAMS ((tree));
483 void expand_builtin_init_dwarf_reg_sizes PARAMS ((tree));
484 void expand_builtin_eh_return PARAMS ((tree, tree, tree));
486 void expand_eh_return PARAMS ((void));
489 /* Checking whether 2 instructions are within the same exception region. */
491 int in_same_eh_region PARAMS ((rtx, rtx));
492 void free_insn_eh_region PARAMS ((void));
493 void init_insn_eh_region PARAMS ((rtx, int));