1 /* Exception Handling interface routines.
2 Copyright (C) 1996 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. */
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 START_LABEL is the label corresponding to the start of the region.
43 END_LABEL is the label corresponding to the end of the region.
45 EXCEPTION_HANDLER_LABEL is the label corresponding to the handler
48 FINALIZATION is the tree codes for the handler, or is NULL_TREE if
49 one hasn't been generated yet, or is integer_zero_node to mark the
50 end of a group of try blocks. */
55 rtx exception_handler_label;
60 /* A list of EH_ENTRYs. ENTRY is the entry; CHAIN points to the next
61 entry in the list, or is NULL if this is the last entry. */
64 struct eh_entry *entry;
65 struct eh_node *chain;
68 /* A stack of EH_ENTRYs. TOP is the topmost entry on the stack. TOP is
69 NULL if the stack is empty. */
75 /* A queue of EH_ENTRYs. HEAD is the front of the queue; TAIL is the
76 end (the latest entry). HEAD and TAIL are NULL if the queue is
85 /* Start an exception handling region. All instructions emitted after
86 this point are considered to be part of the region until
87 expand_eh_region_end () is invoked. */
89 extern void expand_eh_region_start PROTO((void));
91 /* Just like expand_eh_region_start, except if a cleanup action is
92 entered on the cleanup chain, the TREE_PURPOSE of the element put
93 on the chain is DECL. DECL should be the associated VAR_DECL, if
94 any, otherwise it should be NULL_TREE. */
96 extern void expand_eh_region_start_for_decl PROTO((tree));
98 /* Start an exception handling region for the given cleanup action.
99 All instructions emitted after this point are considered to be part
100 of the region until expand_eh_region_end () is invoked. CLEANUP is
101 the cleanup action to perform. The return value is true if the
102 exception region was optimized away. If that case,
103 expand_eh_region_end does not need to be called for this cleanup,
106 This routine notices one particular common case in C++ code
107 generation, and optimizes it so as to not need the exception
110 extern int expand_eh_region_start_tree PROTO((tree, tree));
112 /* End an exception handling region. The information about the region
113 is found on the top of ehstack.
115 HANDLER is either the cleanup for the exception region, or if we're
116 marking the end of a try block, HANDLER is integer_zero_node.
118 HANDLER will be transformed to rtl when expand_leftover_cleanups ()
121 extern void expand_eh_region_end PROTO((tree));
123 /* Push RLABEL or TLABEL onto LABELSTACK. Only one of RLABEL or TLABEL
124 should be set; the other must be NULL. */
126 extern void push_label_entry PROTO((struct label_node **labelstack, rtx rlabel, tree tlabel));
128 /* Pop the topmost entry from LABELSTACK and return its value as an
129 rtx node. If LABELSTACK is empty, return NULL. */
131 extern rtx pop_label_entry PROTO((struct label_node **labelstack));
133 /* Return the topmost entry of LABELSTACK as a tree node, or return
134 NULL_TREE if LABELSTACK is empty. */
136 extern tree top_label_entry PROTO((struct label_node **labelstack));
138 /* A set of insns for the catch clauses in the current function. They
139 will be emitted at the end of the current function. */
141 extern rtx catch_clauses;
147 /* Toplevel initialization for EH. */
149 extern void init_eh PROTO((void));
151 /* Initialization for the per-function EH data. */
153 extern void init_eh_for_function PROTO((void));
155 /* Saves the current per-function EH data into P. */
157 extern void save_eh_status PROTO((struct function *p));
159 /* Restores the per-function EH data from P. */
161 extern void restore_eh_status PROTO((struct function *p));
163 /* Adds an EH table entry for EH entry number N. Called from
164 final_scan_insn for NOTE_INSN_EH_REGION_BEG. */
166 extern void add_eh_table_entry PROTO((int n));
168 /* Returns a non-zero value if we need to output an exception table. */
170 extern int exception_table_p PROTO((void));
172 /* Outputs the exception table if we have one. */
174 extern void output_exception_table PROTO((void));
176 /* Given a return address in ADDR, determine the address we should use
177 to find the corresponding EH region. */
179 extern rtx eh_outer_context PROTO((rtx addr));
181 /* Called at the start of a block of try statements for which there is
182 a supplied catch handler. */
184 extern void expand_start_try_stmts PROTO((void));
186 /* Called at the start of a block of catch statements. It terminates the
187 previous set of try statements. */
189 extern void expand_start_all_catch PROTO((void));
191 /* Called at the end of a block of catch statements. */
193 extern void expand_end_all_catch PROTO((void));
196 /* Create a new exception region and add the handler for the region
197 onto a list. These regions will be ended (and their handlers
198 emitted) when end_protect_partials is invoked. */
200 extern void add_partial_entry PROTO((tree handler));
203 /* End all of the pending exception regions that have handlers added with
204 push_protect_entry (). */
206 extern void end_protect_partials PROTO((void));
208 /* An internal throw with a direct CONTEXT we want to throw
209 from. CONTEXT must be a label. */
211 extern void expand_internal_throw PROTO((rtx context));
213 /* Called from expand_exception_blocks and expand_end_catch_block to
214 expand and pending handlers. */
216 extern void expand_leftover_cleanups PROTO((void));
218 /* If necessary, emit insns for the start of per-function unwinder for
219 the current function. */
221 extern void emit_unwinder PROTO((void));
223 /* If necessary, emit insns for the end of the per-function unwinder
224 for the current function. */
226 extern void end_eh_unwinder PROTO((void));
228 /* Builds a list of handler labels and puts them in the global
229 variable exception_handler_labels. */
231 extern void find_exception_handler_labels PROTO((void));
233 /* Performs sanity checking on the check_exception_handler_labels
236 extern void check_exception_handler_labels PROTO((void));
238 /* A stack used to keep track of the label used to resume normal program
239 flow out of the current exception handler region. */
241 extern struct label_node *caught_return_label_stack;
243 /* A random area used for purposes elsewhere. */
245 extern struct label_node *false_label_stack;
247 /* A list of labels used for exception handlers. It is created by
248 find_exception_handler_labels for the optimization passes. */
250 extern rtx exception_handler_labels;
252 /* The rtx for the saved PC value. */
254 extern rtx eh_saved_pc_rtx;
256 /* Performs optimizations for exception handling, such as removing
257 unnecessary exception regions. Invoked from jump_optimize (). */
259 extern void exception_optimize PROTO((void));
261 /* Get the dynamic handler chain. */
262 extern rtx get_dynamic_handler_chain PROTO((void));
264 /* Get the dynamic cleanup chain. */
265 extern rtx get_dynamic_cleanup_chain PROTO((void));
267 /* Throw an exception. */
269 extern void emit_throw PROTO((void));
271 /* One to use setjmp/longjmp method of generating code. */
273 extern int exceptions_via_longjmp;
275 /* One to enable asynchronous exception support. */
277 extern int asynchronous_exceptions;
279 /* One to protect cleanup actions with a handler that calls
280 __terminate, zero otherwise. */
282 extern int protect_cleanup_actions_with_terminate;
285 extern tree protect_with_terminate PROTO((tree));