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 stack (TREE_LIST) of lists of handlers. The TREE_VALUE of each
129 node is itself a TREE_CHAINed list of handlers for regions that
130 are not yet closed. The TREE_VALUE of each entry contains the
131 handler for the corresponding entry on the ehstack. */
132 union tree_node
*x_protect_list
;
133 /* The EH context. Nonzero if the function has already
134 fetched a pointer to the EH context for exception handling. */
136 /* The label generated by expand_builtin_eh_return. */
137 rtx x_eh_return_stub_label
;
140 #define ehstack (current_function->eh->x_ehstack)
141 #define catchstack (current_function->eh->x_catchstack)
142 #define ehqueue (current_function->eh->x_ehqueue)
143 #define catch_clauses (current_function->eh->x_catch_clauses)
144 #define false_label_stack (current_function->eh->x_false_label_stack)
145 #define caught_return_label_stack (current_function->eh->x_caught_return_label_stack)
146 #define protect_list (current_function->eh->x_protect_list)
147 #define current_function_ehc (current_function->eh->ehc)
148 #define eh_return_stub_label (current_function->eh->x_eh_return_stub_label)
151 /* Start an exception handling region. All instructions emitted after
152 this point are considered to be part of the region until
153 expand_eh_region_end () is invoked. */
155 extern void expand_eh_region_start
PROTO((void));
157 /* Just like expand_eh_region_start, except if a cleanup action is
158 entered on the cleanup chain, the TREE_PURPOSE of the element put
159 on the chain is DECL. DECL should be the associated VAR_DECL, if
160 any, otherwise it should be NULL_TREE. */
162 extern void expand_eh_region_start_for_decl
PROTO((tree
));
164 /* Start an exception handling region for the given cleanup action.
165 All instructions emitted after this point are considered to be part
166 of the region until expand_eh_region_end () is invoked. CLEANUP is
167 the cleanup action to perform. The return value is true if the
168 exception region was optimized away. If that case,
169 expand_eh_region_end does not need to be called for this cleanup,
172 This routine notices one particular common case in C++ code
173 generation, and optimizes it so as to not need the exception
176 extern int expand_eh_region_start_tree
PROTO((tree
, tree
));
178 /* End an exception handling region. The information about the region
179 is found on the top of ehstack.
181 HANDLER is either the cleanup for the exception region, or if we're
182 marking the end of a try block, HANDLER is integer_zero_node.
184 HANDLER will be transformed to rtl when expand_leftover_cleanups ()
187 extern void expand_eh_region_end
PROTO((tree
));
189 /* Push RLABEL or TLABEL onto LABELSTACK. Only one of RLABEL or TLABEL
190 should be set; the other must be NULL. */
192 extern void push_label_entry
PROTO((struct label_node
**labelstack
, rtx rlabel
, tree tlabel
));
194 /* Pop the topmost entry from LABELSTACK and return its value as an
195 rtx node. If LABELSTACK is empty, return NULL. */
197 extern rtx pop_label_entry
PROTO((struct label_node
**labelstack
));
199 /* Return the topmost entry of LABELSTACK as a tree node, or return
200 NULL_TREE if LABELSTACK is empty. */
202 extern tree top_label_entry
PROTO((struct label_node
**labelstack
));
206 /* Test: is exception handling turned on? */
208 extern int doing_eh
PROTO ((int));
210 /* Toplevel initialization for EH. */
212 void set_exception_lang_code
PROTO((int));
213 void set_exception_version_code
PROTO((int));
215 /* A list of handlers asocciated with an exception region. HANDLER_LABEL
216 is the the label that control should be transfered to if the data
217 in TYPE_INFO matches an exception. a value of NULL_TREE for TYPE_INFO
218 means This is a cleanup, and must always be called. A value of
219 CATCH_ALL_TYPE works like a cleanup, but a call to the runtime matcher
220 is still performed to avoid being caught by a different language
221 exception. NEXT is a pointer to the next handler for this region.
222 NULL means there are no more. */
224 typedef struct handler_info
229 struct handler_info
*next
;
233 /* Add new handler information to an exception range. The first parameter
234 specifies the range number (returned from new_eh_entry()). The second
235 parameter specifies the handler. By default the handler is inserted at
236 the end of the list. A handler list may contain only ONE NULL_TREE
237 typeinfo entry. Regardless where it is positioned, a NULL_TREE entry
238 is always output as the LAST handler in the exception table for a region. */
240 void add_new_handler
PROTO((int, struct handler_info
*));
242 /* Remove a handler label. The handler label is being deleted, so all
243 regions which reference this handler should have it removed from their
244 list of possible handlers. Any region which has the final handler
245 removed can be deleted. */
247 void remove_handler
PROTO((rtx
));
249 /* Create a new handler structure initialized with the handler label and
250 typeinfo fields passed in. */
252 struct handler_info
*get_new_handler
PROTO((rtx
, void *));
254 /* Make a duplicate of an exception region by copying all the handlers
255 for an exception region. Return the new handler index. */
257 int duplicate_eh_handlers
PROTO((int, int, rtx (*)(rtx
)));
259 /* map symbol refs for rethrow */
261 rtx rethrow_symbol_map
PROTO((rtx
, rtx (*)(rtx
)));
263 /* Is the rethrow label for a region used? */
265 int rethrow_used
PROTO((int));
267 /* Update the rethrow references to reflect rethrows which have been
270 void update_rethrow_references
PROTO((void));
272 /* Get a pointer to the first handler in an exception region's list. */
274 struct handler_info
*get_first_handler
PROTO((int));
276 /* Find all the runtime handlers type matches currently referenced */
278 int find_all_handler_type_matches
PROTO((void ***));
280 /* The eh_nesting_info structure is used to find a list of valid handlers
281 for any arbitrary exception region. When init_eh_nesting_info is called,
282 the information is all pre-calculated and entered in this structure.
283 REGION_INDEX is a vector over all possible region numbers. Since the
284 number of regions is typically much smaller than the range of block
285 numbers, this is a sparse vector and the other data structures are
286 represented as dense vectors. Indexed with an exception region number, this
287 returns the index to use in the other data structures to retreive the
289 HANDLERS is an array of vectors which point to handler_info structures.
290 when indexed, it gives the list of all possible handlers which can
291 be reached by a throw from this exception region.
292 NUM_HANDLERS is the equivilent array indicating how many handler
293 pointers there are in the HANDLERS vector.
294 OUTER_INDEX indicates which index represents the information for the
295 outer block. 0 indicates there is no outer context.
296 REGION_COUNT is the number of regions. */
298 typedef struct eh_nesting
301 handler_info
***handlers
;
307 /* Initialize the eh_nesting_info structure. */
309 eh_nesting_info
*init_eh_nesting_info
PROTO((void));
311 /* Get a list of handlers reachable from a an exception region/insn. */
313 int reachable_handlers
PROTO((int, eh_nesting_info
*, rtx
,
314 handler_info
***handlers
));
316 /* Free the eh_nesting_info structure. */
318 void free_eh_nesting_info
PROTO((eh_nesting_info
*));
320 extern void init_eh
PROTO((void));
322 /* Initialization for the per-function EH data. */
324 extern void init_eh_for_function
PROTO((void));
326 /* Generate an exception label. Use instead of gen_label_rtx */
328 extern rtx gen_exception_label
PROTO((void));
330 /* Adds an EH table entry for EH entry number N. Called from
331 final_scan_insn for NOTE_INSN_EH_REGION_BEG. */
333 extern void add_eh_table_entry
PROTO((int n
));
335 /* Start a catch clause, triggered by runtime value paramter. */
338 extern void start_catch_handler
PROTO((tree
));
341 /* End an individual catch clause. */
343 extern void end_catch_handler
PROTO((void));
345 /* Returns a non-zero value if we need to output an exception table. */
347 extern int exception_table_p
PROTO((void));
349 /* Outputs the exception table if we have one. */
351 extern void output_exception_table
PROTO((void));
353 /* Given a return address in ADDR, determine the address we should use
354 to find the corresponding EH region. */
356 extern rtx eh_outer_context
PROTO((rtx addr
));
358 /* Called at the start of a block of try statements for which there is
359 a supplied catch handler. */
361 extern void expand_start_try_stmts
PROTO((void));
363 /* Called at the start of a block of catch statements. It terminates the
364 previous set of try statements. */
366 extern void expand_start_all_catch
PROTO((void));
368 /* Called at the end of a block of catch statements. */
370 extern void expand_end_all_catch
PROTO((void));
372 /* Begin a region that will contain entries created with
373 add_partial_entry. */
375 extern void begin_protect_partials
PROTO((void));
378 /* Create a new exception region and add the handler for the region
379 onto a list. These regions will be ended (and their handlers
380 emitted) when end_protect_partials is invoked. */
382 extern void add_partial_entry
PROTO((tree handler
));
385 /* End all of the pending exception regions that have handlers added with
386 push_protect_entry (). */
388 extern void end_protect_partials
PROTO((void));
390 /* An internal throw. */
392 extern void expand_internal_throw
PROTO((void));
394 /* Called from expand_exception_blocks and expand_end_catch_block to
395 expand and pending handlers. */
397 extern void expand_leftover_cleanups
PROTO((void));
399 /* If necessary, emit insns to get EH context for the current
402 extern void emit_eh_context
PROTO((void));
404 /* Builds a list of handler labels and puts them in the global
405 variable exception_handler_labels. */
407 extern void find_exception_handler_labels
PROTO((void));
409 /* Determine if an arbitrary label is an exception label */
411 extern int is_exception_handler_label
PROTO((int));
413 /* Performs sanity checking on the check_exception_handler_labels
416 extern void check_exception_handler_labels
PROTO((void));
418 /* Keeps track of the label used as the context of a throw to rethrow an
419 exception to the outer exception region. */
421 extern struct label_node
*outer_context_label_stack
;
423 /* A list of labels used for exception handlers. It is created by
424 find_exception_handler_labels for the optimization passes. */
426 extern rtx exception_handler_labels
;
428 /* Performs optimizations for exception handling, such as removing
429 unnecessary exception regions. Invoked from jump_optimize (). */
431 extern void exception_optimize
PROTO((void));
433 /* Return EH context (and set it up once per fn). */
434 extern rtx get_eh_context
PROTO((void));
436 /* Get the dynamic handler chain. */
437 extern rtx get_dynamic_handler_chain
PROTO((void));
439 /* Get the dynamic cleanup chain. */
440 extern rtx get_dynamic_cleanup_chain
PROTO((void));
442 /* Throw an exception. */
444 extern void emit_throw
PROTO((void));
446 /* One to use setjmp/longjmp method of generating code. */
448 extern int exceptions_via_longjmp
;
450 /* One to enable asynchronous exception support. */
452 extern int asynchronous_exceptions
;
454 /* One to protect cleanup actions with a handler that calls
455 __terminate, zero otherwise. */
457 extern int protect_cleanup_actions_with_terminate
;
460 extern tree protect_with_terminate
PROTO((tree
));
463 extern void expand_fixup_region_start
PROTO((void));
465 extern void expand_fixup_region_end
PROTO((tree
));
468 /* Various hooks for the DWARF 2 __throw routine. */
470 void expand_builtin_unwind_init
PROTO((void));
471 rtx expand_builtin_dwarf_fp_regnum
PROTO((void));
473 rtx expand_builtin_frob_return_addr
PROTO((tree
));
474 rtx expand_builtin_extract_return_addr
PROTO((tree
));
475 void expand_builtin_init_dwarf_reg_sizes
PROTO((tree
));
476 void expand_builtin_eh_return
PROTO((tree
, tree
, tree
));
478 void expand_eh_return
PROTO((void));
481 /* Checking whether 2 instructions are within the same exception region. */
483 int in_same_eh_region
PROTO((rtx
, rtx
));
484 void free_insn_eh_region
PROTO((void));
485 void init_insn_eh_region
PROTO((rtx
, int));