1 /* Implements exception handling.
2 Copyright (C) 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
3 1999, 2000 Free Software Foundation, Inc.
4 Contributed by Mike Stump <mrs@cygnus.com>.
6 This file is part of GNU CC.
8 GNU CC is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 2, or (at your option)
13 GNU CC is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
18 You should have received a copy of the GNU General Public License
19 along with GNU CC; see the file COPYING. If not, write to
20 the Free Software Foundation, 59 Temple Place - Suite 330,
21 Boston, MA 02111-1307, USA. */
24 /* An exception is an event that can be signaled from within a
25 function. This event can then be "caught" or "trapped" by the
26 callers of this function. This potentially allows program flow to
27 be transferred to any arbitrary code associated with a function call
28 several levels up the stack.
30 The intended use for this mechanism is for signaling "exceptional
31 events" in an out-of-band fashion, hence its name. The C++ language
32 (and many other OO-styled or functional languages) practically
33 requires such a mechanism, as otherwise it becomes very difficult
34 or even impossible to signal failure conditions in complex
35 situations. The traditional C++ example is when an error occurs in
36 the process of constructing an object; without such a mechanism, it
37 is impossible to signal that the error occurs without adding global
38 state variables and error checks around every object construction.
40 The act of causing this event to occur is referred to as "throwing
41 an exception". (Alternate terms include "raising an exception" or
42 "signaling an exception".) The term "throw" is used because control
43 is returned to the callers of the function that is signaling the
44 exception, and thus there is the concept of "throwing" the
45 exception up the call stack.
47 There are two major codegen options for exception handling. The
48 flag -fsjlj-exceptions can be used to select the setjmp/longjmp
49 approach, which is the default. -fno-sjlj-exceptions can be used to
50 get the PC range table approach. While this is a compile time
51 flag, an entire application must be compiled with the same codegen
52 option. The first is a PC range table approach, the second is a
53 setjmp/longjmp based scheme. We will first discuss the PC range
54 table approach, after that, we will discuss the setjmp/longjmp
57 It is appropriate to speak of the "context of a throw". This
58 context refers to the address where the exception is thrown from,
59 and is used to determine which exception region will handle the
62 Regions of code within a function can be marked such that if it
63 contains the context of a throw, control will be passed to a
64 designated "exception handler". These areas are known as "exception
65 regions". Exception regions cannot overlap, but they can be nested
66 to any arbitrary depth. Also, exception regions cannot cross
69 Exception handlers can either be specified by the user (which we
70 will call a "user-defined handler") or generated by the compiler
71 (which we will designate as a "cleanup"). Cleanups are used to
72 perform tasks such as destruction of objects allocated on the
75 In the current implementation, cleanups are handled by allocating an
76 exception region for the area that the cleanup is designated for,
77 and the handler for the region performs the cleanup and then
78 rethrows the exception to the outer exception region. From the
79 standpoint of the current implementation, there is little
80 distinction made between a cleanup and a user-defined handler, and
81 the phrase "exception handler" can be used to refer to either one
82 equally well. (The section "Future Directions" below discusses how
85 Each object file that is compiled with exception handling contains
86 a static array of exception handlers named __EXCEPTION_TABLE__.
87 Each entry contains the starting and ending addresses of the
88 exception region, and the address of the handler designated for
91 If the target does not use the DWARF 2 frame unwind information, at
92 program startup each object file invokes a function named
93 __register_exceptions with the address of its local
94 __EXCEPTION_TABLE__. __register_exceptions is defined in libgcc2.c, and
95 is responsible for recording all of the exception regions into one list
96 (which is kept in a static variable named exception_table_list).
98 On targets that support crtstuff.c, the unwind information
99 is stored in a section named .eh_frame and the information for the
100 entire shared object or program is registered with a call to
101 __register_frame_info. On other targets, the information for each
102 translation unit is registered from the file generated by collect2.
103 __register_frame_info is defined in frame.c, and is responsible for
104 recording all of the unwind regions into one list (which is kept in a
105 static variable named unwind_table_list).
107 The function __throw is actually responsible for doing the
108 throw. On machines that have unwind info support, __throw is generated
109 by code in libgcc2.c, otherwise __throw is generated on a
110 per-object-file basis for each source file compiled with
111 -fexceptions by the C++ frontend. Before __throw is invoked,
112 the current context of the throw needs to be placed in the global
115 __throw attempts to find the appropriate exception handler for the
116 PC value stored in __eh_pc by calling __find_first_exception_table_match
117 (which is defined in libgcc2.c). If __find_first_exception_table_match
118 finds a relevant handler, __throw transfers control directly to it.
120 If a handler for the context being thrown from can't be found, __throw
121 walks (see Walking the stack below) the stack up the dynamic call chain to
122 continue searching for an appropriate exception handler based upon the
123 caller of the function it last sought a exception handler for. It stops
124 then either an exception handler is found, or when the top of the
125 call chain is reached.
127 If no handler is found, an external library function named
128 __terminate is called. If a handler is found, then we restart
129 our search for a handler at the end of the call chain, and repeat
130 the search process, but instead of just walking up the call chain,
131 we unwind the call chain as we walk up it.
133 Internal implementation details:
135 To associate a user-defined handler with a block of statements, the
136 function expand_start_try_stmts is used to mark the start of the
137 block of statements with which the handler is to be associated
138 (which is known as a "try block"). All statements that appear
139 afterwards will be associated with the try block.
141 A call to expand_start_all_catch marks the end of the try block,
142 and also marks the start of the "catch block" (the user-defined
143 handler) associated with the try block.
145 This user-defined handler will be invoked for *every* exception
146 thrown with the context of the try block. It is up to the handler
147 to decide whether or not it wishes to handle any given exception,
148 as there is currently no mechanism in this implementation for doing
149 this. (There are plans for conditionally processing an exception
150 based on its "type", which will provide a language-independent
153 If the handler chooses not to process the exception (perhaps by
154 looking at an "exception type" or some other additional data
155 supplied with the exception), it can fall through to the end of the
156 handler. expand_end_all_catch and expand_leftover_cleanups
157 add additional code to the end of each handler to take care of
158 rethrowing to the outer exception handler.
160 The handler also has the option to continue with "normal flow of
161 code", or in other words to resume executing at the statement
162 immediately after the end of the exception region. The variable
163 caught_return_label_stack contains a stack of labels, and jumping
164 to the topmost entry's label via expand_goto will resume normal
165 flow to the statement immediately after the end of the exception
166 region. If the handler falls through to the end, the exception will
167 be rethrown to the outer exception region.
169 The instructions for the catch block are kept as a separate
170 sequence, and will be emitted at the end of the function along with
171 the handlers specified via expand_eh_region_end. The end of the
172 catch block is marked with expand_end_all_catch.
174 Any data associated with the exception must currently be handled by
175 some external mechanism maintained in the frontend. For example,
176 the C++ exception mechanism passes an arbitrary value along with
177 the exception, and this is handled in the C++ frontend by using a
178 global variable to hold the value. (This will be changing in the
181 The mechanism in C++ for handling data associated with the
182 exception is clearly not thread-safe. For a thread-based
183 environment, another mechanism must be used (possibly using a
184 per-thread allocation mechanism if the size of the area that needs
185 to be allocated isn't known at compile time.)
187 Internally-generated exception regions (cleanups) are marked by
188 calling expand_eh_region_start to mark the start of the region,
189 and expand_eh_region_end (handler) is used to both designate the
190 end of the region and to associate a specified handler/cleanup with
191 the region. The rtl code in HANDLER will be invoked whenever an
192 exception occurs in the region between the calls to
193 expand_eh_region_start and expand_eh_region_end. After HANDLER is
194 executed, additional code is emitted to handle rethrowing the
195 exception to the outer exception handler. The code for HANDLER will
196 be emitted at the end of the function.
198 TARGET_EXPRs can also be used to designate exception regions. A
199 TARGET_EXPR gives an unwind-protect style interface commonly used
200 in functional languages such as LISP. The associated expression is
201 evaluated, and whether or not it (or any of the functions that it
202 calls) throws an exception, the protect expression is always
203 invoked. This implementation takes care of the details of
204 associating an exception table entry with the expression and
205 generating the necessary code (it actually emits the protect
206 expression twice, once for normal flow and once for the exception
207 case). As for the other handlers, the code for the exception case
208 will be emitted at the end of the function.
210 Cleanups can also be specified by using add_partial_entry (handler)
211 and end_protect_partials. add_partial_entry creates the start of
212 a new exception region; HANDLER will be invoked if an exception is
213 thrown with the context of the region between the calls to
214 add_partial_entry and end_protect_partials. end_protect_partials is
215 used to mark the end of these regions. add_partial_entry can be
216 called as many times as needed before calling end_protect_partials.
217 However, end_protect_partials should only be invoked once for each
218 group of calls to add_partial_entry as the entries are queued
219 and all of the outstanding entries are processed simultaneously
220 when end_protect_partials is invoked. Similarly to the other
221 handlers, the code for HANDLER will be emitted at the end of the
224 The generated RTL for an exception region includes
225 NOTE_INSN_EH_REGION_BEG and NOTE_INSN_EH_REGION_END notes that mark
226 the start and end of the exception region. A unique label is also
227 generated at the start of the exception region, which is available
228 by looking at the ehstack variable. The topmost entry corresponds
229 to the current region.
231 In the current implementation, an exception can only be thrown from
232 a function call (since the mechanism used to actually throw an
233 exception involves calling __throw). If an exception region is
234 created but no function calls occur within that region, the region
235 can be safely optimized away (along with its exception handlers)
236 since no exceptions can ever be caught in that region. This
237 optimization is performed unless -fasynchronous-exceptions is
238 given. If the user wishes to throw from a signal handler, or other
239 asynchronous place, -fasynchronous-exceptions should be used when
240 compiling for maximally correct code, at the cost of additional
241 exception regions. Using -fasynchronous-exceptions only produces
242 code that is reasonably safe in such situations, but a correct
243 program cannot rely upon this working. It can be used in failsafe
244 code, where trying to continue on, and proceeding with potentially
245 incorrect results is better than halting the program.
250 The stack is walked by starting with a pointer to the current
251 frame, and finding the pointer to the callers frame. The unwind info
252 tells __throw how to find it.
256 When we use the term unwinding the stack, we mean undoing the
257 effects of the function prologue in a controlled fashion so that we
258 still have the flow of control. Otherwise, we could just return
259 (jump to the normal end of function epilogue).
261 This is done in __throw in libgcc2.c when we know that a handler exists
262 in a frame higher up the call stack than its immediate caller.
264 To unwind, we find the unwind data associated with the frame, if any.
265 If we don't find any, we call the library routine __terminate. If we do
266 find it, we use the information to copy the saved register values from
267 that frame into the register save area in the frame for __throw, return
268 into a stub which updates the stack pointer, and jump to the handler.
269 The normal function epilogue for __throw handles restoring the saved
270 values into registers.
272 When unwinding, we use this method if we know it will
273 work (if DWARF2_UNWIND_INFO is defined). Otherwise, we know that
274 an inline unwinder will have been emitted for any function that
275 __unwind_function cannot unwind. The inline unwinder appears as a
276 normal exception handler for the entire function, for any function
277 that we know cannot be unwound by __unwind_function. We inform the
278 compiler of whether a function can be unwound with
279 __unwind_function by having DOESNT_NEED_UNWINDER evaluate to true
280 when the unwinder isn't needed. __unwind_function is used as an
281 action of last resort. If no other method can be used for
282 unwinding, __unwind_function is used. If it cannot unwind, it
283 should call __terminate.
285 By default, if the target-specific backend doesn't supply a definition
286 for __unwind_function and doesn't support DWARF2_UNWIND_INFO, inlined
287 unwinders will be used instead. The main tradeoff here is in text space
288 utilization. Obviously, if inline unwinders have to be generated
289 repeatedly, this uses much more space than if a single routine is used.
291 However, it is simply not possible on some platforms to write a
292 generalized routine for doing stack unwinding without having some
293 form of additional data associated with each function. The current
294 implementation can encode this data in the form of additional
295 machine instructions or as static data in tabular form. The later
296 is called the unwind data.
298 The backend macro DOESNT_NEED_UNWINDER is used to conditionalize whether
299 or not per-function unwinders are needed. If DOESNT_NEED_UNWINDER is
300 defined and has a non-zero value, a per-function unwinder is not emitted
301 for the current function. If the static unwind data is supported, then
302 a per-function unwinder is not emitted.
304 On some platforms it is possible that neither __unwind_function
305 nor inlined unwinders are available. For these platforms it is not
306 possible to throw through a function call, and abort will be
307 invoked instead of performing the throw.
309 The reason the unwind data may be needed is that on some platforms
310 the order and types of data stored on the stack can vary depending
311 on the type of function, its arguments and returned values, and the
312 compilation options used (optimization versus non-optimization,
313 -fomit-frame-pointer, processor variations, etc).
315 Unfortunately, this also means that throwing through functions that
316 aren't compiled with exception handling support will still not be
317 possible on some platforms. This problem is currently being
318 investigated, but no solutions have been found that do not imply
319 some unacceptable performance penalties.
323 Currently __throw makes no differentiation between cleanups and
324 user-defined exception regions. While this makes the implementation
325 simple, it also implies that it is impossible to determine if a
326 user-defined exception handler exists for a given exception without
327 completely unwinding the stack in the process. This is undesirable
328 from the standpoint of debugging, as ideally it would be possible
329 to trap unhandled exceptions in the debugger before the process of
330 unwinding has even started.
332 This problem can be solved by marking user-defined handlers in a
333 special way (probably by adding additional bits to exception_table_list).
334 A two-pass scheme could then be used by __throw to iterate
335 through the table. The first pass would search for a relevant
336 user-defined handler for the current context of the throw, and if
337 one is found, the second pass would then invoke all needed cleanups
338 before jumping to the user-defined handler.
340 Many languages (including C++ and Ada) make execution of a
341 user-defined handler conditional on the "type" of the exception
342 thrown. (The type of the exception is actually the type of the data
343 that is thrown with the exception.) It will thus be necessary for
344 __throw to be able to determine if a given user-defined
345 exception handler will actually be executed, given the type of
348 One scheme is to add additional information to exception_table_list
349 as to the types of exceptions accepted by each handler. __throw
350 can do the type comparisons and then determine if the handler is
351 actually going to be executed.
353 There is currently no significant level of debugging support
354 available, other than to place a breakpoint on __throw. While
355 this is sufficient in most cases, it would be helpful to be able to
356 know where a given exception was going to be thrown to before it is
357 actually thrown, and to be able to choose between stopping before
358 every exception region (including cleanups), or just user-defined
359 exception regions. This should be possible to do in the two-pass
360 scheme by adding additional labels to __throw for appropriate
361 breakpoints, and additional debugger commands could be added to
362 query various state variables to determine what actions are to be
365 Another major problem that is being worked on is the issue with stack
366 unwinding on various platforms. Currently the only platforms that have
367 support for the generation of a generic unwinder are the SPARC and MIPS.
368 All other ports require per-function unwinders, which produce large
369 amounts of code bloat.
371 For setjmp/longjmp based exception handling, some of the details
372 are as above, but there are some additional details. This section
373 discusses the details.
375 We don't use NOTE_INSN_EH_REGION_{BEG,END} pairs. We don't
376 optimize EH regions yet. We don't have to worry about machine
377 specific issues with unwinding the stack, as we rely upon longjmp
378 for all the machine specific details. There is no variable context
379 of a throw, just the one implied by the dynamic handler stack
380 pointed to by the dynamic handler chain. There is no exception
381 table, and no calls to __register_exceptions. __sjthrow is used
382 instead of __throw, and it works by using the dynamic handler
383 chain, and longjmp. -fasynchronous-exceptions has no effect, as
384 the elimination of trivial exception regions is not yet performed.
386 A frontend can set protect_cleanup_actions_with_terminate when all
387 the cleanup actions should be protected with an EH region that
388 calls terminate when an unhandled exception is throw. C++ does
389 this, Ada does not. */
393 #include "defaults.h"
394 #include "eh-common.h"
400 #include "function.h"
401 #include "insn-flags.h"
403 #include "insn-codes.h"
405 #include "hard-reg-set.h"
406 #include "insn-config.h"
415 /* One to use setjmp/longjmp method of generating code for exception
418 int exceptions_via_longjmp = 2;
420 /* One to enable asynchronous exception support. */
422 int asynchronous_exceptions = 0;
424 /* One to protect cleanup actions with a handler that calls
425 __terminate, zero otherwise. */
427 int protect_cleanup_actions_with_terminate;
429 /* A list of labels used for exception handlers. Created by
430 find_exception_handler_labels for the optimization passes. */
432 rtx exception_handler_labels;
434 /* Keeps track of the label used as the context of a throw to rethrow an
435 exception to the outer exception region. */
437 struct label_node *outer_context_label_stack = NULL;
439 /* Pseudos used to hold exception return data in the interim between
440 __builtin_eh_return and the end of the function. */
442 static rtx eh_return_context;
443 static rtx eh_return_stack_adjust;
444 static rtx eh_return_handler;
446 /* This is used for targets which can call rethrow with an offset instead
447 of an address. This is subtracted from the rethrow label we are
450 static rtx first_rethrow_symbol = NULL_RTX;
451 static rtx final_rethrow = NULL_RTX;
452 static rtx last_rethrow_symbol = NULL_RTX;
455 /* Prototypes for local functions. */
457 static void push_eh_entry PARAMS ((struct eh_stack *));
458 static struct eh_entry * pop_eh_entry PARAMS ((struct eh_stack *));
459 static void enqueue_eh_entry PARAMS ((struct eh_queue *, struct eh_entry *));
460 static struct eh_entry * dequeue_eh_entry PARAMS ((struct eh_queue *));
461 static rtx call_get_eh_context PARAMS ((void));
462 static void start_dynamic_cleanup PARAMS ((tree, tree));
463 static void start_dynamic_handler PARAMS ((void));
464 static void expand_rethrow PARAMS ((rtx));
465 static void output_exception_table_entry PARAMS ((FILE *, int));
466 static rtx scan_region PARAMS ((rtx, int, int *));
467 static void eh_regs PARAMS ((rtx *, rtx *, rtx *, int));
468 static void set_insn_eh_region PARAMS ((rtx *, int));
469 #ifdef DONT_USE_BUILTIN_SETJMP
470 static void jumpif_rtx PARAMS ((rtx, rtx));
472 static void find_exception_handler_labels_1 PARAMS ((rtx));
473 static void mark_eh_node PARAMS ((struct eh_node *));
474 static void mark_eh_stack PARAMS ((struct eh_stack *));
475 static void mark_eh_queue PARAMS ((struct eh_queue *));
476 static void mark_tree_label_node PARAMS ((struct label_node *));
477 static void mark_func_eh_entry PARAMS ((void *));
478 static rtx create_rethrow_ref PARAMS ((int));
479 static void push_entry PARAMS ((struct eh_stack *, struct eh_entry*));
480 static void receive_exception_label PARAMS ((rtx));
481 static int new_eh_region_entry PARAMS ((int, rtx));
482 static int find_func_region PARAMS ((int));
483 static int find_func_region_from_symbol PARAMS ((rtx));
484 static void clear_function_eh_region PARAMS ((void));
485 static void process_nestinfo PARAMS ((int, eh_nesting_info *, int *));
486 rtx expand_builtin_return_addr PARAMS ((enum built_in_function, int, rtx));
487 static void emit_cleanup_handler PARAMS ((struct eh_entry *));
488 static int eh_region_from_symbol PARAMS ((rtx));
491 /* Various support routines to manipulate the various data structures
492 used by the exception handling code. */
494 extern struct obstack permanent_obstack;
496 /* Generate a SYMBOL_REF for rethrow to use */
499 create_rethrow_ref (region_num)
506 push_obstacks_nochange ();
507 end_temporary_allocation ();
509 ASM_GENERATE_INTERNAL_LABEL (buf, "LRTH", region_num);
510 ptr = ggc_alloc_string (buf, -1);
511 def = gen_rtx_SYMBOL_REF (Pmode, ptr);
512 SYMBOL_REF_NEED_ADJUST (def) = 1;
518 /* Push a label entry onto the given STACK. */
521 push_label_entry (stack, rlabel, tlabel)
522 struct label_node **stack;
526 struct label_node *newnode
527 = (struct label_node *) xmalloc (sizeof (struct label_node));
530 newnode->u.rlabel = rlabel;
532 newnode->u.tlabel = tlabel;
533 newnode->chain = *stack;
537 /* Pop a label entry from the given STACK. */
540 pop_label_entry (stack)
541 struct label_node **stack;
544 struct label_node *tempnode;
550 label = tempnode->u.rlabel;
551 *stack = (*stack)->chain;
557 /* Return the top element of the given STACK. */
560 top_label_entry (stack)
561 struct label_node **stack;
566 return (*stack)->u.tlabel;
569 /* Get an exception label. */
572 gen_exception_label ()
575 lab = gen_label_rtx ();
579 /* Push a new eh_node entry onto STACK. */
582 push_eh_entry (stack)
583 struct eh_stack *stack;
585 struct eh_node *node = (struct eh_node *) xmalloc (sizeof (struct eh_node));
586 struct eh_entry *entry = (struct eh_entry *) xmalloc (sizeof (struct eh_entry));
588 rtx rlab = gen_exception_label ();
589 entry->finalization = NULL_TREE;
590 entry->label_used = 0;
591 entry->exception_handler_label = rlab;
592 entry->false_label = NULL_RTX;
593 if (! flag_new_exceptions)
594 entry->outer_context = gen_label_rtx ();
596 entry->outer_context = create_rethrow_ref (CODE_LABEL_NUMBER (rlab));
597 entry->rethrow_label = entry->outer_context;
598 entry->goto_entry_p = 0;
601 node->chain = stack->top;
605 /* Push an existing entry onto a stack. */
608 push_entry (stack, entry)
609 struct eh_stack *stack;
610 struct eh_entry *entry;
612 struct eh_node *node = (struct eh_node *) xmalloc (sizeof (struct eh_node));
614 node->chain = stack->top;
618 /* Pop an entry from the given STACK. */
620 static struct eh_entry *
622 struct eh_stack *stack;
624 struct eh_node *tempnode;
625 struct eh_entry *tempentry;
627 tempnode = stack->top;
628 tempentry = tempnode->entry;
629 stack->top = stack->top->chain;
635 /* Enqueue an ENTRY onto the given QUEUE. */
638 enqueue_eh_entry (queue, entry)
639 struct eh_queue *queue;
640 struct eh_entry *entry;
642 struct eh_node *node = (struct eh_node *) xmalloc (sizeof (struct eh_node));
647 if (queue->head == NULL)
650 queue->tail->chain = node;
654 /* Dequeue an entry from the given QUEUE. */
656 static struct eh_entry *
657 dequeue_eh_entry (queue)
658 struct eh_queue *queue;
660 struct eh_node *tempnode;
661 struct eh_entry *tempentry;
663 if (queue->head == NULL)
666 tempnode = queue->head;
667 queue->head = queue->head->chain;
669 tempentry = tempnode->entry;
676 receive_exception_label (handler_label)
679 emit_label (handler_label);
681 #ifdef HAVE_exception_receiver
682 if (! exceptions_via_longjmp)
683 if (HAVE_exception_receiver)
684 emit_insn (gen_exception_receiver ());
687 #ifdef HAVE_nonlocal_goto_receiver
688 if (! exceptions_via_longjmp)
689 if (HAVE_nonlocal_goto_receiver)
690 emit_insn (gen_nonlocal_goto_receiver ());
697 int range_number; /* EH region number from EH NOTE insn's. */
698 rtx rethrow_label; /* Label for rethrow. */
699 int rethrow_ref; /* Is rethrow_label referenced? */
700 int emitted; /* 1 if this entry has been emitted in assembly file. */
701 struct handler_info *handlers;
705 /* table of function eh regions */
706 static struct func_eh_entry *function_eh_regions = NULL;
707 static int num_func_eh_entries = 0;
708 static int current_func_eh_entry = 0;
710 #define SIZE_FUNC_EH(X) (sizeof (struct func_eh_entry) * X)
712 /* Add a new eh_entry for this function. The number returned is an
713 number which uniquely identifies this exception range. */
716 new_eh_region_entry (note_eh_region, rethrow)
720 if (current_func_eh_entry == num_func_eh_entries)
722 if (num_func_eh_entries == 0)
724 function_eh_regions =
725 (struct func_eh_entry *) xmalloc (SIZE_FUNC_EH (50));
726 num_func_eh_entries = 50;
730 num_func_eh_entries = num_func_eh_entries * 3 / 2;
731 function_eh_regions = (struct func_eh_entry *)
732 xrealloc (function_eh_regions, SIZE_FUNC_EH (num_func_eh_entries));
735 function_eh_regions[current_func_eh_entry].range_number = note_eh_region;
736 if (rethrow == NULL_RTX)
737 function_eh_regions[current_func_eh_entry].rethrow_label =
738 create_rethrow_ref (note_eh_region);
740 function_eh_regions[current_func_eh_entry].rethrow_label = rethrow;
741 function_eh_regions[current_func_eh_entry].handlers = NULL;
742 function_eh_regions[current_func_eh_entry].emitted = 0;
744 return current_func_eh_entry++;
747 /* Add new handler information to an exception range. The first parameter
748 specifies the range number (returned from new_eh_entry()). The second
749 parameter specifies the handler. By default the handler is inserted at
750 the end of the list. A handler list may contain only ONE NULL_TREE
751 typeinfo entry. Regardless where it is positioned, a NULL_TREE entry
752 is always output as the LAST handler in the exception table for a region. */
755 add_new_handler (region, newhandler)
757 struct handler_info *newhandler;
759 struct handler_info *last;
761 /* If find_func_region returns -1, callers might attempt to pass us
762 this region number. If that happens, something has gone wrong;
763 -1 is never a valid region. */
767 newhandler->next = NULL;
768 last = function_eh_regions[region].handlers;
770 function_eh_regions[region].handlers = newhandler;
773 for ( ; ; last = last->next)
775 if (last->type_info == CATCH_ALL_TYPE)
776 pedwarn ("additional handler after ...");
777 if (last->next == NULL)
780 last->next = newhandler;
784 /* Remove a handler label. The handler label is being deleted, so all
785 regions which reference this handler should have it removed from their
786 list of possible handlers. Any region which has the final handler
787 removed can be deleted. */
789 void remove_handler (removing_label)
792 struct handler_info *handler, *last;
794 for (x = 0 ; x < current_func_eh_entry; ++x)
797 handler = function_eh_regions[x].handlers;
798 for ( ; handler; last = handler, handler = handler->next)
799 if (handler->handler_label == removing_label)
803 last->next = handler->next;
807 function_eh_regions[x].handlers = handler->next;
812 /* This function will return a malloc'd pointer to an array of
813 void pointer representing the runtime match values that
814 currently exist in all regions. */
817 find_all_handler_type_matches (array)
820 struct handler_info *handler, *last;
829 if (!doing_eh (0) || ! flag_new_exceptions)
833 ptr = (void **) xmalloc (max_ptr * sizeof (void *));
835 for (x = 0 ; x < current_func_eh_entry; x++)
838 handler = function_eh_regions[x].handlers;
839 for ( ; handler; last = handler, handler = handler->next)
841 val = handler->type_info;
842 if (val != NULL && val != CATCH_ALL_TYPE)
844 /* See if this match value has already been found. */
845 for (y = 0; y < n_ptr; y++)
849 /* If we break early, we already found this value. */
853 /* Do we need to allocate more space? */
854 if (n_ptr >= max_ptr)
856 max_ptr += max_ptr / 2;
857 ptr = (void **) xrealloc (ptr, max_ptr * sizeof (void *));
874 /* Create a new handler structure initialized with the handler label and
875 typeinfo fields passed in. */
877 struct handler_info *
878 get_new_handler (handler, typeinfo)
882 struct handler_info* ptr;
883 ptr = (struct handler_info *) xmalloc (sizeof (struct handler_info));
884 ptr->handler_label = handler;
885 ptr->handler_number = CODE_LABEL_NUMBER (handler);
886 ptr->type_info = typeinfo;
894 /* Find the index in function_eh_regions associated with a NOTE region. If
895 the region cannot be found, a -1 is returned. */
898 find_func_region (insn_region)
902 for (x = 0; x < current_func_eh_entry; x++)
903 if (function_eh_regions[x].range_number == insn_region)
909 /* Get a pointer to the first handler in an exception region's list. */
911 struct handler_info *
912 get_first_handler (region)
915 int r = find_func_region (region);
918 return function_eh_regions[r].handlers;
921 /* Clean out the function_eh_region table and free all memory */
924 clear_function_eh_region ()
927 struct handler_info *ptr, *next;
928 for (x = 0; x < current_func_eh_entry; x++)
929 for (ptr = function_eh_regions[x].handlers; ptr != NULL; ptr = next)
934 if (function_eh_regions)
935 free (function_eh_regions);
936 num_func_eh_entries = 0;
937 current_func_eh_entry = 0;
940 /* Make a duplicate of an exception region by copying all the handlers
941 for an exception region. Return the new handler index. The final
942 parameter is a routine which maps old labels to new ones. */
945 duplicate_eh_handlers (old_note_eh_region, new_note_eh_region, map)
946 int old_note_eh_region, new_note_eh_region;
947 rtx (*map) PARAMS ((rtx));
949 struct handler_info *ptr, *new_ptr;
950 int new_region, region;
952 region = find_func_region (old_note_eh_region);
954 fatal ("Cannot duplicate non-existant exception region.");
956 /* duplicate_eh_handlers may have been called during a symbol remap. */
957 new_region = find_func_region (new_note_eh_region);
958 if (new_region != -1)
961 new_region = new_eh_region_entry (new_note_eh_region, NULL_RTX);
963 ptr = function_eh_regions[region].handlers;
965 for ( ; ptr; ptr = ptr->next)
967 new_ptr = get_new_handler (map (ptr->handler_label), ptr->type_info);
968 add_new_handler (new_region, new_ptr);
975 /* Given a rethrow symbol, find the EH region number this is for. */
978 eh_region_from_symbol (sym)
982 if (sym == last_rethrow_symbol)
984 for (x = 0; x < current_func_eh_entry; x++)
985 if (function_eh_regions[x].rethrow_label == sym)
986 return function_eh_regions[x].range_number;
990 /* Like find_func_region, but using the rethrow symbol for the region
991 rather than the region number itself. */
994 find_func_region_from_symbol (sym)
997 return find_func_region (eh_region_from_symbol (sym));
1000 /* When inlining/unrolling, we have to map the symbols passed to
1001 __rethrow as well. This performs the remap. If a symbol isn't foiund,
1002 the original one is returned. This is not an efficient routine,
1003 so don't call it on everything!! */
1006 rethrow_symbol_map (sym, map)
1008 rtx (*map) PARAMS ((rtx));
1012 if (! flag_new_exceptions)
1015 for (x = 0; x < current_func_eh_entry; x++)
1016 if (function_eh_regions[x].rethrow_label == sym)
1018 /* We've found the original region, now lets determine which region
1019 this now maps to. */
1020 rtx l1 = function_eh_regions[x].handlers->handler_label;
1022 y = CODE_LABEL_NUMBER (l2); /* This is the new region number */
1023 x = find_func_region (y); /* Get the new permanent region */
1024 if (x == -1) /* Hmm, Doesn't exist yet */
1026 x = duplicate_eh_handlers (CODE_LABEL_NUMBER (l1), y, map);
1027 /* Since we're mapping it, it must be used. */
1028 function_eh_regions[x].rethrow_ref = 1;
1030 return function_eh_regions[x].rethrow_label;
1035 /* Returns nonzero if the rethrow label for REGION is referenced
1036 somewhere (i.e. we rethrow out of REGION or some other region
1037 masquerading as REGION). */
1040 rethrow_used (region)
1043 if (flag_new_exceptions)
1045 int ret = function_eh_regions[find_func_region (region)].rethrow_ref;
1052 /* Routine to see if exception handling is turned on.
1053 DO_WARN is non-zero if we want to inform the user that exception
1054 handling is turned off.
1056 This is used to ensure that -fexceptions has been specified if the
1057 compiler tries to use any exception-specific functions. */
1063 if (! flag_exceptions)
1065 static int warned = 0;
1066 if (! warned && do_warn)
1068 error ("exception handling disabled, use -fexceptions to enable");
1076 /* Given a return address in ADDR, determine the address we should use
1077 to find the corresponding EH region. */
1080 eh_outer_context (addr)
1083 /* First mask out any unwanted bits. */
1084 #ifdef MASK_RETURN_ADDR
1085 expand_and (addr, MASK_RETURN_ADDR, addr);
1088 /* Then adjust to find the real return address. */
1089 #if defined (RETURN_ADDR_OFFSET)
1090 addr = plus_constant (addr, RETURN_ADDR_OFFSET);
1096 /* Start a new exception region for a region of code that has a
1097 cleanup action and push the HANDLER for the region onto
1098 protect_list. All of the regions created with add_partial_entry
1099 will be ended when end_protect_partials is invoked. */
1102 add_partial_entry (handler)
1105 expand_eh_region_start ();
1107 /* Make sure the entry is on the correct obstack. */
1108 push_obstacks_nochange ();
1109 resume_temporary_allocation ();
1111 /* Because this is a cleanup action, we may have to protect the handler
1112 with __terminate. */
1113 handler = protect_with_terminate (handler);
1115 /* For backwards compatibility, we allow callers to omit calls to
1116 begin_protect_partials for the outermost region. So, we must
1117 explicitly do so here. */
1119 begin_protect_partials ();
1121 /* Add this entry to the front of the list. */
1122 TREE_VALUE (protect_list)
1123 = tree_cons (NULL_TREE, handler, TREE_VALUE (protect_list));
1127 /* Emit code to get EH context to current function. */
1130 call_get_eh_context ()
1135 if (fn == NULL_TREE)
1138 fn = get_identifier ("__get_eh_context");
1139 push_obstacks_nochange ();
1140 end_temporary_allocation ();
1141 fntype = build_pointer_type (build_pointer_type
1142 (build_pointer_type (void_type_node)));
1143 fntype = build_function_type (fntype, NULL_TREE);
1144 fn = build_decl (FUNCTION_DECL, fn, fntype);
1145 DECL_EXTERNAL (fn) = 1;
1146 TREE_PUBLIC (fn) = 1;
1147 DECL_ARTIFICIAL (fn) = 1;
1148 TREE_READONLY (fn) = 1;
1149 make_decl_rtl (fn, NULL_PTR, 1);
1150 assemble_external (fn);
1153 ggc_add_tree_root (&fn, 1);
1156 expr = build1 (ADDR_EXPR, build_pointer_type (TREE_TYPE (fn)), fn);
1157 expr = build (CALL_EXPR, TREE_TYPE (TREE_TYPE (fn)),
1158 expr, NULL_TREE, NULL_TREE);
1159 TREE_SIDE_EFFECTS (expr) = 1;
1161 return copy_to_reg (expand_expr (expr, NULL_RTX, VOIDmode, 0));
1164 /* Get a reference to the EH context.
1165 We will only generate a register for the current function EH context here,
1166 and emit a USE insn to mark that this is a EH context register.
1168 Later, emit_eh_context will emit needed call to __get_eh_context
1169 in libgcc2, and copy the value to the register we have generated. */
1174 if (current_function_ehc == 0)
1178 current_function_ehc = gen_reg_rtx (Pmode);
1180 insn = gen_rtx_USE (GET_MODE (current_function_ehc),
1181 current_function_ehc);
1182 insn = emit_insn_before (insn, get_first_nonparm_insn ());
1185 = gen_rtx_EXPR_LIST (REG_EH_CONTEXT, current_function_ehc,
1188 return current_function_ehc;
1191 /* Get a reference to the dynamic handler chain. It points to the
1192 pointer to the next element in the dynamic handler chain. It ends
1193 when there are no more elements in the dynamic handler chain, when
1194 the value is &top_elt from libgcc2.c. Immediately after the
1195 pointer, is an area suitable for setjmp/longjmp when
1196 DONT_USE_BUILTIN_SETJMP is defined, and an area suitable for
1197 __builtin_setjmp/__builtin_longjmp when DONT_USE_BUILTIN_SETJMP
1201 get_dynamic_handler_chain ()
1203 rtx ehc, dhc, result;
1205 ehc = get_eh_context ();
1207 /* This is the offset of dynamic_handler_chain in the eh_context struct
1208 declared in eh-common.h. If its location is change, change this offset */
1209 dhc = plus_constant (ehc, POINTER_SIZE / BITS_PER_UNIT);
1211 result = copy_to_reg (dhc);
1213 /* We don't want a copy of the dcc, but rather, the single dcc. */
1214 return gen_rtx_MEM (Pmode, result);
1217 /* Get a reference to the dynamic cleanup chain. It points to the
1218 pointer to the next element in the dynamic cleanup chain.
1219 Immediately after the pointer, are two Pmode variables, one for a
1220 pointer to a function that performs the cleanup action, and the
1221 second, the argument to pass to that function. */
1224 get_dynamic_cleanup_chain ()
1226 rtx dhc, dcc, result;
1228 dhc = get_dynamic_handler_chain ();
1229 dcc = plus_constant (dhc, POINTER_SIZE / BITS_PER_UNIT);
1231 result = copy_to_reg (dcc);
1233 /* We don't want a copy of the dcc, but rather, the single dcc. */
1234 return gen_rtx_MEM (Pmode, result);
1237 #ifdef DONT_USE_BUILTIN_SETJMP
1238 /* Generate code to evaluate X and jump to LABEL if the value is nonzero.
1239 LABEL is an rtx of code CODE_LABEL, in this function. */
1242 jumpif_rtx (x, label)
1246 jumpif (make_tree (type_for_mode (GET_MODE (x), 0), x), label);
1250 /* Start a dynamic cleanup on the EH runtime dynamic cleanup stack.
1251 We just need to create an element for the cleanup list, and push it
1254 A dynamic cleanup is a cleanup action implied by the presence of an
1255 element on the EH runtime dynamic cleanup stack that is to be
1256 performed when an exception is thrown. The cleanup action is
1257 performed by __sjthrow when an exception is thrown. Only certain
1258 actions can be optimized into dynamic cleanup actions. For the
1259 restrictions on what actions can be performed using this routine,
1260 see expand_eh_region_start_tree. */
1263 start_dynamic_cleanup (func, arg)
1268 rtx new_func, new_arg;
1272 /* We allocate enough room for a pointer to the function, and
1276 /* XXX, FIXME: The stack space allocated this way is too long lived,
1277 but there is no allocation routine that allocates at the level of
1278 the last binding contour. */
1279 buf = assign_stack_local (BLKmode,
1280 GET_MODE_SIZE (Pmode)*(size+1),
1283 buf = change_address (buf, Pmode, NULL_RTX);
1285 /* Store dcc into the first word of the newly allocated buffer. */
1287 dcc = get_dynamic_cleanup_chain ();
1288 emit_move_insn (buf, dcc);
1290 /* Store func and arg into the cleanup list element. */
1292 new_func = gen_rtx_MEM (Pmode, plus_constant (XEXP (buf, 0),
1293 GET_MODE_SIZE (Pmode)));
1294 new_arg = gen_rtx_MEM (Pmode, plus_constant (XEXP (buf, 0),
1295 GET_MODE_SIZE (Pmode)*2));
1296 x = expand_expr (func, new_func, Pmode, 0);
1298 emit_move_insn (new_func, x);
1300 x = expand_expr (arg, new_arg, Pmode, 0);
1302 emit_move_insn (new_arg, x);
1304 /* Update the cleanup chain. */
1306 x = force_operand (XEXP (buf, 0), dcc);
1308 emit_move_insn (dcc, x);
1311 /* Emit RTL to start a dynamic handler on the EH runtime dynamic
1312 handler stack. This should only be used by expand_eh_region_start
1313 or expand_eh_region_start_tree. */
1316 start_dynamic_handler ()
1322 #ifndef DONT_USE_BUILTIN_SETJMP
1323 /* The number of Pmode words for the setjmp buffer, when using the
1324 builtin setjmp/longjmp, see expand_builtin, case BUILT_IN_LONGJMP. */
1325 /* We use 2 words here before calling expand_builtin_setjmp.
1326 expand_builtin_setjmp uses 2 words, and then calls emit_stack_save.
1327 emit_stack_save needs space of size STACK_SAVEAREA_MODE (SAVE_NONLOCAL).
1328 Subtract one, because the assign_stack_local call below adds 1. */
1329 size = (2 + 2 + (GET_MODE_SIZE (STACK_SAVEAREA_MODE (SAVE_NONLOCAL))
1330 / GET_MODE_SIZE (Pmode))
1334 size = JMP_BUF_SIZE;
1336 /* Should be large enough for most systems, if it is not,
1337 JMP_BUF_SIZE should be defined with the proper value. It will
1338 also tend to be larger than necessary for most systems, a more
1339 optimal port will define JMP_BUF_SIZE. */
1340 size = FIRST_PSEUDO_REGISTER+2;
1343 /* XXX, FIXME: The stack space allocated this way is too long lived,
1344 but there is no allocation routine that allocates at the level of
1345 the last binding contour. */
1346 arg = assign_stack_local (BLKmode,
1347 GET_MODE_SIZE (Pmode)*(size+1),
1350 arg = change_address (arg, Pmode, NULL_RTX);
1352 /* Store dhc into the first word of the newly allocated buffer. */
1354 dhc = get_dynamic_handler_chain ();
1355 dcc = gen_rtx_MEM (Pmode, plus_constant (XEXP (arg, 0),
1356 GET_MODE_SIZE (Pmode)));
1357 emit_move_insn (arg, dhc);
1359 /* Zero out the start of the cleanup chain. */
1360 emit_move_insn (dcc, const0_rtx);
1362 /* The jmpbuf starts two words into the area allocated. */
1363 buf = plus_constant (XEXP (arg, 0), GET_MODE_SIZE (Pmode)*2);
1365 #ifdef DONT_USE_BUILTIN_SETJMP
1366 x = emit_library_call_value (setjmp_libfunc, NULL_RTX, LCT_CONST,
1367 TYPE_MODE (integer_type_node), 1,
1369 /* If we come back here for a catch, transfer control to the handler. */
1370 jumpif_rtx (x, ehstack.top->entry->exception_handler_label);
1373 /* A label to continue execution for the no exception case. */
1374 rtx noex = gen_label_rtx();
1375 x = expand_builtin_setjmp (buf, NULL_RTX, noex,
1376 ehstack.top->entry->exception_handler_label);
1381 /* We are committed to this, so update the handler chain. */
1383 emit_move_insn (dhc, force_operand (XEXP (arg, 0), NULL_RTX));
1386 /* Start an exception handling region for the given cleanup action.
1387 All instructions emitted after this point are considered to be part
1388 of the region until expand_eh_region_end is invoked. CLEANUP is
1389 the cleanup action to perform. The return value is true if the
1390 exception region was optimized away. If that case,
1391 expand_eh_region_end does not need to be called for this cleanup,
1394 This routine notices one particular common case in C++ code
1395 generation, and optimizes it so as to not need the exception
1396 region. It works by creating a dynamic cleanup action, instead of
1397 a using an exception region. */
1400 expand_eh_region_start_tree (decl, cleanup)
1404 /* This is the old code. */
1408 /* The optimization only applies to actions protected with
1409 terminate, and only applies if we are using the setjmp/longjmp
1411 if (exceptions_via_longjmp
1412 && protect_cleanup_actions_with_terminate)
1417 /* Ignore any UNSAVE_EXPR. */
1418 if (TREE_CODE (cleanup) == UNSAVE_EXPR)
1419 cleanup = TREE_OPERAND (cleanup, 0);
1421 /* Further, it only applies if the action is a call, if there
1422 are 2 arguments, and if the second argument is 2. */
1424 if (TREE_CODE (cleanup) == CALL_EXPR
1425 && (args = TREE_OPERAND (cleanup, 1))
1426 && (func = TREE_OPERAND (cleanup, 0))
1427 && (arg = TREE_VALUE (args))
1428 && (args = TREE_CHAIN (args))
1430 /* is the second argument 2? */
1431 && TREE_CODE (TREE_VALUE (args)) == INTEGER_CST
1432 && compare_tree_int (TREE_VALUE (args), 2) == 0
1434 /* Make sure there are no other arguments. */
1435 && TREE_CHAIN (args) == NULL_TREE)
1437 /* Arrange for returns and gotos to pop the entry we make on the
1438 dynamic cleanup stack. */
1439 expand_dcc_cleanup (decl);
1440 start_dynamic_cleanup (func, arg);
1445 expand_eh_region_start_for_decl (decl);
1446 ehstack.top->entry->finalization = cleanup;
1451 /* Just like expand_eh_region_start, except if a cleanup action is
1452 entered on the cleanup chain, the TREE_PURPOSE of the element put
1453 on the chain is DECL. DECL should be the associated VAR_DECL, if
1454 any, otherwise it should be NULL_TREE. */
1457 expand_eh_region_start_for_decl (decl)
1462 /* This is the old code. */
1466 /* We need a new block to record the start and end of the
1467 dynamic handler chain. We also want to prevent jumping into
1469 expand_start_bindings (2);
1471 /* But we don't need or want a new temporary level. */
1474 /* Mark this block as created by expand_eh_region_start. This
1475 is so that we can pop the block with expand_end_bindings
1477 mark_block_as_eh_region ();
1479 if (exceptions_via_longjmp)
1481 /* Arrange for returns and gotos to pop the entry we make on the
1482 dynamic handler stack. */
1483 expand_dhc_cleanup (decl);
1486 push_eh_entry (&ehstack);
1487 note = emit_note (NULL_PTR, NOTE_INSN_EH_REGION_BEG);
1488 NOTE_EH_HANDLER (note)
1489 = CODE_LABEL_NUMBER (ehstack.top->entry->exception_handler_label);
1490 if (exceptions_via_longjmp)
1491 start_dynamic_handler ();
1494 /* Start an exception handling region. All instructions emitted after
1495 this point are considered to be part of the region until
1496 expand_eh_region_end is invoked. */
1499 expand_eh_region_start ()
1501 expand_eh_region_start_for_decl (NULL_TREE);
1504 /* End an exception handling region. The information about the region
1505 is found on the top of ehstack.
1507 HANDLER is either the cleanup for the exception region, or if we're
1508 marking the end of a try block, HANDLER is integer_zero_node.
1510 HANDLER will be transformed to rtl when expand_leftover_cleanups
1514 expand_eh_region_end (handler)
1517 struct eh_entry *entry;
1518 struct eh_node *node;
1525 entry = pop_eh_entry (&ehstack);
1527 note = emit_note (NULL_PTR, NOTE_INSN_EH_REGION_END);
1528 ret = NOTE_EH_HANDLER (note)
1529 = CODE_LABEL_NUMBER (entry->exception_handler_label);
1530 if (exceptions_via_longjmp == 0 && ! flag_new_exceptions
1531 /* We share outer_context between regions; only emit it once. */
1532 && INSN_UID (entry->outer_context) == 0)
1536 label = gen_label_rtx ();
1539 /* Emit a label marking the end of this exception region that
1540 is used for rethrowing into the outer context. */
1541 emit_label (entry->outer_context);
1542 expand_internal_throw ();
1547 entry->finalization = handler;
1549 /* create region entry in final exception table */
1550 r = new_eh_region_entry (NOTE_EH_HANDLER (note), entry->rethrow_label);
1552 enqueue_eh_entry (ehqueue, entry);
1554 /* If we have already started ending the bindings, don't recurse. */
1555 if (is_eh_region ())
1557 /* Because we don't need or want a new temporary level and
1558 because we didn't create one in expand_eh_region_start,
1559 create a fake one now to avoid removing one in
1560 expand_end_bindings. */
1563 mark_block_as_not_eh_region ();
1565 expand_end_bindings (NULL_TREE, 0, 0);
1568 /* Go through the goto handlers in the queue, emitting their
1569 handlers if we now have enough information to do so. */
1570 for (node = ehqueue->head; node; node = node->chain)
1571 if (node->entry->goto_entry_p
1572 && node->entry->outer_context == entry->rethrow_label)
1573 emit_cleanup_handler (node->entry);
1575 /* We can't emit handlers for goto entries until their scopes are
1576 complete because we don't know where they need to rethrow to,
1578 if (entry->finalization != integer_zero_node
1579 && (!entry->goto_entry_p
1580 || find_func_region_from_symbol (entry->outer_context) != -1))
1581 emit_cleanup_handler (entry);
1584 /* End the EH region for a goto fixup. We only need them in the region-based
1588 expand_fixup_region_start ()
1590 if (! doing_eh (0) || exceptions_via_longjmp)
1593 expand_eh_region_start ();
1594 /* Mark this entry as the entry for a goto. */
1595 ehstack.top->entry->goto_entry_p = 1;
1598 /* End the EH region for a goto fixup. CLEANUP is the cleanup we just
1599 expanded; to avoid running it twice if it throws, we look through the
1600 ehqueue for a matching region and rethrow from its outer_context. */
1603 expand_fixup_region_end (cleanup)
1606 struct eh_node *node;
1609 if (! doing_eh (0) || exceptions_via_longjmp)
1612 for (node = ehstack.top; node && node->entry->finalization != cleanup; )
1615 for (node = ehqueue->head; node && node->entry->finalization != cleanup; )
1620 /* If the outer context label has not been issued yet, we don't want
1621 to issue it as a part of this region, unless this is the
1622 correct region for the outer context. If we did, then the label for
1623 the outer context will be WITHIN the begin/end labels,
1624 and we could get an infinte loop when it tried to rethrow, or just
1625 generally incorrect execution following a throw. */
1627 if (flag_new_exceptions)
1630 dont_issue = ((INSN_UID (node->entry->outer_context) == 0)
1631 && (ehstack.top->entry != node->entry));
1633 ehstack.top->entry->outer_context = node->entry->outer_context;
1635 /* Since we are rethrowing to the OUTER region, we know we don't need
1636 a jump around sequence for this region, so we'll pretend the outer
1637 context label has been issued by setting INSN_UID to 1, then clearing
1638 it again afterwards. */
1641 INSN_UID (node->entry->outer_context) = 1;
1643 /* Just rethrow. size_zero_node is just a NOP. */
1644 expand_eh_region_end (size_zero_node);
1647 INSN_UID (node->entry->outer_context) = 0;
1650 /* If we are using the setjmp/longjmp EH codegen method, we emit a
1651 call to __sjthrow. Otherwise, we emit a call to __throw. */
1656 if (exceptions_via_longjmp)
1658 emit_library_call (sjthrow_libfunc, 0, VOIDmode, 0);
1662 #ifdef JUMP_TO_THROW
1663 emit_indirect_jump (throw_libfunc);
1665 emit_library_call (throw_libfunc, 0, VOIDmode, 0);
1671 /* Throw the current exception. If appropriate, this is done by jumping
1672 to the next handler. */
1675 expand_internal_throw ()
1680 /* Called from expand_exception_blocks and expand_end_catch_block to
1681 emit any pending handlers/cleanups queued from expand_eh_region_end. */
1684 expand_leftover_cleanups ()
1686 struct eh_entry *entry;
1688 for (entry = dequeue_eh_entry (ehqueue);
1690 entry = dequeue_eh_entry (ehqueue))
1692 /* A leftover try block. Shouldn't be one here. */
1693 if (entry->finalization == integer_zero_node)
1700 /* Called at the start of a block of try statements. */
1702 expand_start_try_stmts ()
1707 expand_eh_region_start ();
1710 /* Called to begin a catch clause. The parameter is the object which
1711 will be passed to the runtime type check routine. */
1713 start_catch_handler (rtime)
1717 int insn_region_num;
1718 int eh_region_entry;
1723 handler_label = catchstack.top->entry->exception_handler_label;
1724 insn_region_num = CODE_LABEL_NUMBER (handler_label);
1725 eh_region_entry = find_func_region (insn_region_num);
1727 /* If we've already issued this label, pick a new one */
1728 if (catchstack.top->entry->label_used)
1729 handler_label = gen_exception_label ();
1731 catchstack.top->entry->label_used = 1;
1733 receive_exception_label (handler_label);
1735 add_new_handler (eh_region_entry, get_new_handler (handler_label, rtime));
1737 if (flag_new_exceptions && ! exceptions_via_longjmp)
1740 /* Under the old mechanism, as well as setjmp/longjmp, we need to
1741 issue code to compare 'rtime' to the value in eh_info, via the
1742 matching function in eh_info. If its is false, we branch around
1743 the handler we are about to issue. */
1745 if (rtime != NULL_TREE && rtime != CATCH_ALL_TYPE)
1747 rtx call_rtx, rtime_address;
1749 if (catchstack.top->entry->false_label != NULL_RTX)
1751 error ("Never issued previous false_label");
1754 catchstack.top->entry->false_label = gen_exception_label ();
1756 rtime_address = expand_expr (rtime, NULL_RTX, Pmode, EXPAND_INITIALIZER);
1757 #ifdef POINTERS_EXTEND_UNSIGNED
1758 rtime_address = convert_memory_address (Pmode, rtime_address);
1760 rtime_address = force_reg (Pmode, rtime_address);
1762 /* Now issue the call, and branch around handler if needed */
1763 call_rtx = emit_library_call_value (eh_rtime_match_libfunc, NULL_RTX,
1765 TYPE_MODE (integer_type_node),
1766 1, rtime_address, Pmode);
1768 /* Did the function return true? */
1769 emit_cmp_and_jump_insns (call_rtx, const0_rtx, EQ, NULL_RTX,
1770 GET_MODE (call_rtx), 0, 0,
1771 catchstack.top->entry->false_label);
1775 /* Called to end a catch clause. If we aren't using the new exception
1776 model tabel mechanism, we need to issue the branch-around label
1777 for the end of the catch block. */
1780 end_catch_handler ()
1785 if (flag_new_exceptions && ! exceptions_via_longjmp)
1791 /* A NULL label implies the catch clause was a catch all or cleanup */
1792 if (catchstack.top->entry->false_label == NULL_RTX)
1795 emit_label (catchstack.top->entry->false_label);
1796 catchstack.top->entry->false_label = NULL_RTX;
1799 /* Save away the current ehqueue. */
1805 q = (struct eh_queue *) xcalloc (1, sizeof (struct eh_queue));
1810 /* Restore a previously pushed ehqueue. */
1816 expand_leftover_cleanups ();
1822 /* Emit the handler specified by ENTRY. */
1825 emit_cleanup_handler (entry)
1826 struct eh_entry *entry;
1831 /* Since the cleanup could itself contain try-catch blocks, we
1832 squirrel away the current queue and replace it when we are done
1833 with this function. */
1836 /* Put these handler instructions in a sequence. */
1837 do_pending_stack_adjust ();
1840 /* Emit the label for the cleanup handler for this region, and
1841 expand the code for the handler.
1843 Note that a catch region is handled as a side-effect here; for a
1844 try block, entry->finalization will contain integer_zero_node, so
1845 no code will be generated in the expand_expr call below. But, the
1846 label for the handler will still be emitted, so any code emitted
1847 after this point will end up being the handler. */
1849 receive_exception_label (entry->exception_handler_label);
1851 /* register a handler for this cleanup region */
1852 add_new_handler (find_func_region (CODE_LABEL_NUMBER (entry->exception_handler_label)),
1853 get_new_handler (entry->exception_handler_label, NULL));
1855 /* And now generate the insns for the cleanup handler. */
1856 expand_expr (entry->finalization, const0_rtx, VOIDmode, 0);
1858 prev = get_last_insn ();
1859 if (prev == NULL || GET_CODE (prev) != BARRIER)
1860 /* Code to throw out to outer context when we fall off end of the
1861 handler. We can't do this here for catch blocks, so it's done
1862 in expand_end_all_catch instead. */
1863 expand_rethrow (entry->outer_context);
1865 /* Finish this sequence. */
1866 do_pending_stack_adjust ();
1867 handler_insns = get_insns ();
1870 /* And add it to the CATCH_CLAUSES. */
1871 push_to_full_sequence (catch_clauses, catch_clauses_last);
1872 emit_insns (handler_insns);
1873 end_full_sequence (&catch_clauses, &catch_clauses_last);
1875 /* Now we've left the handler. */
1879 /* Generate RTL for the start of a group of catch clauses.
1881 It is responsible for starting a new instruction sequence for the
1882 instructions in the catch block, and expanding the handlers for the
1883 internally-generated exception regions nested within the try block
1884 corresponding to this catch block. */
1887 expand_start_all_catch ()
1889 struct eh_entry *entry;
1896 outer_context = ehstack.top->entry->outer_context;
1898 /* End the try block. */
1899 expand_eh_region_end (integer_zero_node);
1901 emit_line_note (input_filename, lineno);
1902 label = build_decl (LABEL_DECL, NULL_TREE, NULL_TREE);
1904 /* The label for the exception handling block that we will save.
1905 This is Lresume in the documentation. */
1906 expand_label (label);
1908 /* Push the label that points to where normal flow is resumed onto
1909 the top of the label stack. */
1910 push_label_entry (&caught_return_label_stack, NULL_RTX, label);
1912 /* Start a new sequence for all the catch blocks. We will add this
1913 to the global sequence catch_clauses when we have completed all
1914 the handlers in this handler-seq. */
1917 /* Throw away entries in the queue that we won't need anymore. We
1918 need entries for regions that have ended but to which there might
1919 still be gotos pending. */
1920 for (entry = dequeue_eh_entry (ehqueue);
1921 entry->finalization != integer_zero_node;
1922 entry = dequeue_eh_entry (ehqueue))
1925 /* At this point, all the cleanups are done, and the ehqueue now has
1926 the current exception region at its head. We dequeue it, and put it
1927 on the catch stack. */
1928 push_entry (&catchstack, entry);
1930 /* If we are not doing setjmp/longjmp EH, because we are reordered
1931 out of line, we arrange to rethrow in the outer context. We need to
1932 do this because we are not physically within the region, if any, that
1933 logically contains this catch block. */
1934 if (! exceptions_via_longjmp)
1936 expand_eh_region_start ();
1937 ehstack.top->entry->outer_context = outer_context;
1942 /* Finish up the catch block. At this point all the insns for the
1943 catch clauses have already been generated, so we only have to add
1944 them to the catch_clauses list. We also want to make sure that if
1945 we fall off the end of the catch clauses that we rethrow to the
1949 expand_end_all_catch ()
1951 rtx new_catch_clause;
1952 struct eh_entry *entry;
1957 /* Dequeue the current catch clause region. */
1958 entry = pop_eh_entry (&catchstack);
1961 if (! exceptions_via_longjmp)
1963 rtx outer_context = ehstack.top->entry->outer_context;
1965 /* Finish the rethrow region. size_zero_node is just a NOP. */
1966 expand_eh_region_end (size_zero_node);
1967 /* New exceptions handling models will never have a fall through
1968 of a catch clause */
1969 if (!flag_new_exceptions)
1970 expand_rethrow (outer_context);
1973 expand_rethrow (NULL_RTX);
1975 /* Code to throw out to outer context, if we fall off end of catch
1976 handlers. This is rethrow (Lresume, same id, same obj) in the
1977 documentation. We use Lresume because we know that it will throw
1978 to the correct context.
1980 In other words, if the catch handler doesn't exit or return, we
1981 do a "throw" (using the address of Lresume as the point being
1982 thrown from) so that the outer EH region can then try to process
1985 /* Now we have the complete catch sequence. */
1986 new_catch_clause = get_insns ();
1989 /* This level of catch blocks is done, so set up the successful
1990 catch jump label for the next layer of catch blocks. */
1991 pop_label_entry (&caught_return_label_stack);
1992 pop_label_entry (&outer_context_label_stack);
1994 /* Add the new sequence of catches to the main one for this function. */
1995 push_to_full_sequence (catch_clauses, catch_clauses_last);
1996 emit_insns (new_catch_clause);
1997 end_full_sequence (&catch_clauses, &catch_clauses_last);
1999 /* Here we fall through into the continuation code. */
2002 /* Rethrow from the outer context LABEL. */
2005 expand_rethrow (label)
2008 if (exceptions_via_longjmp)
2011 if (flag_new_exceptions)
2015 if (label == NULL_RTX)
2016 label = last_rethrow_symbol;
2017 emit_library_call (rethrow_libfunc, 0, VOIDmode, 1, label, Pmode);
2018 region = find_func_region (eh_region_from_symbol (label));
2019 /* If the region is -1, it doesn't exist yet. We shouldn't be
2020 trying to rethrow there yet. */
2023 function_eh_regions[region].rethrow_ref = 1;
2025 /* Search backwards for the actual call insn. */
2026 insn = get_last_insn ();
2027 while (GET_CODE (insn) != CALL_INSN)
2028 insn = PREV_INSN (insn);
2029 delete_insns_since (insn);
2031 /* Mark the label/symbol on the call. */
2032 REG_NOTES (insn) = gen_rtx_EXPR_LIST (REG_EH_RETHROW, label,
2040 /* Begin a region that will contain entries created with
2041 add_partial_entry. */
2044 begin_protect_partials ()
2046 /* Put the entry on the function obstack. */
2047 push_obstacks_nochange ();
2048 resume_temporary_allocation ();
2050 /* Push room for a new list. */
2051 protect_list = tree_cons (NULL_TREE, NULL_TREE, protect_list);
2053 /* We're done with the function obstack now. */
2057 /* End all the pending exception regions on protect_list. The handlers
2058 will be emitted when expand_leftover_cleanups is invoked. */
2061 end_protect_partials ()
2065 /* For backwards compatibility, we allow callers to omit the call to
2066 begin_protect_partials for the outermost region. So,
2067 PROTECT_LIST may be NULL. */
2071 /* End all the exception regions. */
2072 for (t = TREE_VALUE (protect_list); t; t = TREE_CHAIN (t))
2073 expand_eh_region_end (TREE_VALUE (t));
2075 /* Pop the topmost entry. */
2076 protect_list = TREE_CHAIN (protect_list);
2080 /* Arrange for __terminate to be called if there is an unhandled throw
2084 protect_with_terminate (e)
2087 /* We only need to do this when using setjmp/longjmp EH and the
2088 language requires it, as otherwise we protect all of the handlers
2089 at once, if we need to. */
2090 if (exceptions_via_longjmp && protect_cleanup_actions_with_terminate)
2092 tree handler, result;
2094 /* All cleanups must be on the function_obstack. */
2095 push_obstacks_nochange ();
2096 resume_temporary_allocation ();
2098 handler = make_node (RTL_EXPR);
2099 TREE_TYPE (handler) = void_type_node;
2100 RTL_EXPR_RTL (handler) = const0_rtx;
2101 TREE_SIDE_EFFECTS (handler) = 1;
2102 start_sequence_for_rtl_expr (handler);
2104 emit_library_call (terminate_libfunc, 0, VOIDmode, 0);
2107 RTL_EXPR_SEQUENCE (handler) = get_insns ();
2110 result = build (TRY_CATCH_EXPR, TREE_TYPE (e), e, handler);
2111 TREE_SIDE_EFFECTS (result) = TREE_SIDE_EFFECTS (e);
2112 TREE_THIS_VOLATILE (result) = TREE_THIS_VOLATILE (e);
2113 TREE_READONLY (result) = TREE_READONLY (e);
2123 /* The exception table that we build that is used for looking up and
2124 dispatching exceptions, the current number of entries, and its
2125 maximum size before we have to extend it.
2127 The number in eh_table is the code label number of the exception
2128 handler for the region. This is added by add_eh_table_entry and
2129 used by output_exception_table_entry. */
2131 static int *eh_table = NULL;
2132 static int eh_table_size = 0;
2133 static int eh_table_max_size = 0;
2135 /* Note the need for an exception table entry for region N. If we
2136 don't need to output an explicit exception table, avoid all of the
2139 Called from final_scan_insn when a NOTE_INSN_EH_REGION_BEG is seen.
2140 (Or NOTE_INSN_EH_REGION_END sometimes)
2141 N is the NOTE_EH_HANDLER of the note, which comes from the code
2142 label number of the exception handler for the region. */
2145 add_eh_table_entry (n)
2148 #ifndef OMIT_EH_TABLE
2149 if (eh_table_size >= eh_table_max_size)
2153 eh_table_max_size += eh_table_max_size>>1;
2155 if (eh_table_max_size < 0)
2158 eh_table = (int *) xrealloc (eh_table,
2159 eh_table_max_size * sizeof (int));
2163 eh_table_max_size = 252;
2164 eh_table = (int *) xmalloc (eh_table_max_size * sizeof (int));
2167 eh_table[eh_table_size++] = n;
2169 if (flag_new_exceptions)
2171 /* We will output the exception table late in the compilation. That
2172 references type_info objects which should have already been output
2173 by that time. We explicitly mark those objects as being
2174 referenced now so we know to emit them. */
2175 struct handler_info *handler = get_first_handler (n);
2177 for (; handler; handler = handler->next)
2178 if (handler->type_info && handler->type_info != CATCH_ALL_TYPE)
2180 tree tinfo = (tree)handler->type_info;
2182 tinfo = TREE_OPERAND (tinfo, 0);
2183 TREE_SYMBOL_REFERENCED (DECL_ASSEMBLER_NAME (tinfo)) = 1;
2189 /* Return a non-zero value if we need to output an exception table.
2191 On some platforms, we don't have to output a table explicitly.
2192 This routine doesn't mean we don't have one. */
2195 exception_table_p ()
2203 /* Output the entry of the exception table corresponding to the
2204 exception region numbered N to file FILE.
2206 N is the code label number corresponding to the handler of the
2210 output_exception_table_entry (file, n)
2216 struct handler_info *handler = get_first_handler (n);
2217 int index = find_func_region (n);
2220 /* Form and emit the rethrow label, if needed */
2221 if (flag_new_exceptions
2222 && (handler || function_eh_regions[index].rethrow_ref))
2223 rethrow = function_eh_regions[index].rethrow_label;
2227 if (function_eh_regions[index].emitted)
2229 function_eh_regions[index].emitted = 1;
2231 for ( ; handler != NULL || rethrow != NULL_RTX; handler = handler->next)
2233 /* rethrow label should indicate the LAST entry for a region */
2234 if (rethrow != NULL_RTX && (handler == NULL || handler->next == NULL))
2236 ASM_GENERATE_INTERNAL_LABEL (buf, "LRTH", n);
2237 assemble_eh_label(buf);
2241 ASM_GENERATE_INTERNAL_LABEL (buf, "LEHB", n);
2242 sym = gen_rtx_SYMBOL_REF (Pmode, buf);
2243 assemble_eh_integer (sym, POINTER_SIZE / BITS_PER_UNIT, 1);
2245 ASM_GENERATE_INTERNAL_LABEL (buf, "LEHE", n);
2246 sym = gen_rtx_SYMBOL_REF (Pmode, buf);
2247 assemble_eh_integer (sym, POINTER_SIZE / BITS_PER_UNIT, 1);
2249 if (handler == NULL)
2250 assemble_eh_integer (GEN_INT (0), POINTER_SIZE / BITS_PER_UNIT, 1);
2253 ASM_GENERATE_INTERNAL_LABEL (buf, "L", handler->handler_number);
2254 sym = gen_rtx_SYMBOL_REF (Pmode, buf);
2255 assemble_eh_integer (sym, POINTER_SIZE / BITS_PER_UNIT, 1);
2258 if (flag_new_exceptions)
2260 if (handler == NULL || handler->type_info == NULL)
2261 assemble_eh_integer (const0_rtx, POINTER_SIZE / BITS_PER_UNIT, 1);
2263 if (handler->type_info == CATCH_ALL_TYPE)
2264 assemble_eh_integer (GEN_INT (CATCH_ALL_TYPE),
2265 POINTER_SIZE / BITS_PER_UNIT, 1);
2267 output_constant ((tree)(handler->type_info),
2268 POINTER_SIZE / BITS_PER_UNIT);
2270 putc ('\n', file); /* blank line */
2271 /* We only output the first label under the old scheme */
2272 if (! flag_new_exceptions || handler == NULL)
2277 /* Output the exception table if we have and need one. */
2279 static short language_code = 0;
2280 static short version_code = 0;
2282 /* This routine will set the language code for exceptions. */
2284 set_exception_lang_code (code)
2287 language_code = code;
2290 /* This routine will set the language version code for exceptions. */
2292 set_exception_version_code (code)
2295 version_code = code;
2298 /* Free the EH table structures. */
2300 free_exception_table ()
2304 clear_function_eh_region ();
2307 /* Output the common content of an exception table. */
2309 output_exception_table_data ()
2313 extern FILE *asm_out_file;
2315 if (flag_new_exceptions)
2317 assemble_eh_integer (GEN_INT (NEW_EH_RUNTIME),
2318 POINTER_SIZE / BITS_PER_UNIT, 1);
2319 assemble_eh_integer (GEN_INT (language_code), 2 , 1);
2320 assemble_eh_integer (GEN_INT (version_code), 2 , 1);
2322 /* Add enough padding to make sure table aligns on a pointer boundry. */
2323 i = GET_MODE_ALIGNMENT (ptr_mode) / BITS_PER_UNIT - 4;
2324 for ( ; i < 0; i = i + GET_MODE_ALIGNMENT (ptr_mode) / BITS_PER_UNIT)
2327 assemble_eh_integer (const0_rtx, i , 1);
2329 /* Generate the label for offset calculations on rethrows. */
2330 ASM_GENERATE_INTERNAL_LABEL (buf, "LRTH", 0);
2331 assemble_eh_label(buf);
2334 for (i = 0; i < eh_table_size; ++i)
2335 output_exception_table_entry (asm_out_file, eh_table[i]);
2339 /* Output an exception table for the entire compilation unit. */
2341 output_exception_table ()
2344 extern FILE *asm_out_file;
2346 if (! doing_eh (0) || ! eh_table)
2349 exception_section ();
2351 /* Beginning marker for table. */
2352 assemble_eh_align (GET_MODE_ALIGNMENT (ptr_mode));
2353 assemble_eh_label ("__EXCEPTION_TABLE__");
2355 output_exception_table_data ();
2357 /* Ending marker for table. */
2358 /* Generate the label for end of table. */
2359 ASM_GENERATE_INTERNAL_LABEL (buf, "LRTH", CODE_LABEL_NUMBER (final_rethrow));
2360 assemble_eh_label(buf);
2361 assemble_eh_integer (constm1_rtx, POINTER_SIZE / BITS_PER_UNIT, 1);
2363 /* For binary compatibility, the old __throw checked the second
2364 position for a -1, so we should output at least 2 -1's */
2365 if (! flag_new_exceptions)
2366 assemble_eh_integer (constm1_rtx, POINTER_SIZE / BITS_PER_UNIT, 1);
2368 putc ('\n', asm_out_file); /* blank line */
2371 /* Used by the ia64 unwind format to output data for an individual
2374 output_function_exception_table ()
2376 extern FILE *asm_out_file;
2378 if (! doing_eh (0) || ! eh_table)
2381 #ifdef HANDLER_SECTION
2385 output_exception_table_data ();
2387 /* Ending marker for table. */
2388 assemble_eh_integer (constm1_rtx, POINTER_SIZE / BITS_PER_UNIT, 1);
2390 putc ('\n', asm_out_file); /* blank line */
2394 /* Emit code to get EH context.
2396 We have to scan thru the code to find possible EH context registers.
2397 Inlined functions may use it too, and thus we'll have to be able
2400 This is done only if using exceptions_via_longjmp. */
2411 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
2412 if (GET_CODE (insn) == INSN
2413 && GET_CODE (PATTERN (insn)) == USE)
2415 rtx reg = find_reg_note (insn, REG_EH_CONTEXT, 0);
2422 /* If this is the first use insn, emit the call here. This
2423 will always be at the top of our function, because if
2424 expand_inline_function notices a REG_EH_CONTEXT note, it
2425 adds a use insn to this function as well. */
2427 ehc = call_get_eh_context ();
2429 emit_move_insn (XEXP (reg, 0), ehc);
2430 insns = get_insns ();
2433 emit_insns_before (insns, insn);
2438 /* Scan the insn chain F and build a list of handler labels. The
2439 resulting list is placed in the global variable exception_handler_labels. */
2442 find_exception_handler_labels_1 (f)
2447 /* For each start of a region, add its label to the list. */
2449 for (insn = f; insn; insn = NEXT_INSN (insn))
2451 struct handler_info* ptr;
2452 if (GET_CODE (insn) == NOTE
2453 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG)
2455 ptr = get_first_handler (NOTE_EH_HANDLER (insn));
2456 for ( ; ptr; ptr = ptr->next)
2458 /* make sure label isn't in the list already */
2460 for (x = exception_handler_labels; x; x = XEXP (x, 1))
2461 if (XEXP (x, 0) == ptr->handler_label)
2464 exception_handler_labels = gen_rtx_EXPR_LIST (VOIDmode,
2465 ptr->handler_label, exception_handler_labels);
2468 else if (GET_CODE (insn) == CALL_INSN
2469 && GET_CODE (PATTERN (insn)) == CALL_PLACEHOLDER)
2471 find_exception_handler_labels_1 (XEXP (PATTERN (insn), 0));
2472 find_exception_handler_labels_1 (XEXP (PATTERN (insn), 1));
2473 find_exception_handler_labels_1 (XEXP (PATTERN (insn), 2));
2478 /* Scan the current insns and build a list of handler labels. The
2479 resulting list is placed in the global variable exception_handler_labels.
2481 It is called after the last exception handling region is added to
2482 the current function (when the rtl is almost all built for the
2483 current function) and before the jump optimization pass. */
2485 find_exception_handler_labels ()
2487 exception_handler_labels = NULL_RTX;
2489 /* If we aren't doing exception handling, there isn't much to check. */
2493 find_exception_handler_labels_1 (get_insns ());
2496 /* Return a value of 1 if the parameter label number is an exception handler
2497 label. Return 0 otherwise. */
2500 is_exception_handler_label (lab)
2504 for (x = exception_handler_labels ; x ; x = XEXP (x, 1))
2505 if (lab == CODE_LABEL_NUMBER (XEXP (x, 0)))
2510 /* Perform sanity checking on the exception_handler_labels list.
2512 Can be called after find_exception_handler_labels is called to
2513 build the list of exception handlers for the current function and
2514 before we finish processing the current function. */
2517 check_exception_handler_labels ()
2521 /* If we aren't doing exception handling, there isn't much to check. */
2525 /* Make sure there is no more than 1 copy of a label */
2526 for (insn = exception_handler_labels; insn; insn = XEXP (insn, 1))
2529 for (insn2 = exception_handler_labels; insn2; insn2 = XEXP (insn2, 1))
2530 if (XEXP (insn, 0) == XEXP (insn2, 0))
2533 warning ("Counted %d copies of EH region %d in list.\n", count,
2534 CODE_LABEL_NUMBER (insn));
2539 /* Mark the children of NODE for GC. */
2543 struct eh_node *node;
2549 ggc_mark_rtx (node->entry->outer_context);
2550 ggc_mark_rtx (node->entry->exception_handler_label);
2551 ggc_mark_tree (node->entry->finalization);
2552 ggc_mark_rtx (node->entry->false_label);
2553 ggc_mark_rtx (node->entry->rethrow_label);
2555 node = node ->chain;
2559 /* Mark S for GC. */
2566 mark_eh_node (s->top);
2569 /* Mark Q for GC. */
2577 mark_eh_node (q->head);
2582 /* Mark NODE for GC. A label_node contains a union containing either
2583 a tree or an rtx. This label_node will contain a tree. */
2586 mark_tree_label_node (node)
2587 struct label_node *node;
2591 ggc_mark_tree (node->u.tlabel);
2596 /* Mark EH for GC. */
2600 struct eh_status *eh;
2605 mark_eh_stack (&eh->x_ehstack);
2606 mark_eh_stack (&eh->x_catchstack);
2607 mark_eh_queue (eh->x_ehqueue);
2608 ggc_mark_rtx (eh->x_catch_clauses);
2610 if (lang_mark_false_label_stack)
2611 (*lang_mark_false_label_stack) (eh->x_false_label_stack);
2612 mark_tree_label_node (eh->x_caught_return_label_stack);
2614 ggc_mark_tree (eh->x_protect_list);
2615 ggc_mark_rtx (eh->ehc);
2616 ggc_mark_rtx (eh->x_eh_return_stub_label);
2619 /* Mark ARG (which is really a struct func_eh_entry**) for GC. */
2622 mark_func_eh_entry (arg)
2625 struct func_eh_entry *fee;
2626 struct handler_info *h;
2629 fee = *((struct func_eh_entry **) arg);
2631 for (i = 0; i < current_func_eh_entry; ++i)
2633 ggc_mark_rtx (fee->rethrow_label);
2634 for (h = fee->handlers; h; h = h->next)
2636 ggc_mark_rtx (h->handler_label);
2637 if (h->type_info != CATCH_ALL_TYPE)
2638 ggc_mark_tree ((tree) h->type_info);
2641 /* Skip to the next entry in the array. */
2646 /* This group of functions initializes the exception handling data
2647 structures at the start of the compilation, initializes the data
2648 structures at the start of a function, and saves and restores the
2649 exception handling data structures for the start/end of a nested
2652 /* Toplevel initialization for EH things. */
2657 first_rethrow_symbol = create_rethrow_ref (0);
2658 final_rethrow = gen_exception_label ();
2659 last_rethrow_symbol = create_rethrow_ref (CODE_LABEL_NUMBER (final_rethrow));
2661 ggc_add_rtx_root (&exception_handler_labels, 1);
2662 ggc_add_rtx_root (&eh_return_context, 1);
2663 ggc_add_rtx_root (&eh_return_stack_adjust, 1);
2664 ggc_add_rtx_root (&eh_return_handler, 1);
2665 ggc_add_rtx_root (&first_rethrow_symbol, 1);
2666 ggc_add_rtx_root (&final_rethrow, 1);
2667 ggc_add_rtx_root (&last_rethrow_symbol, 1);
2668 ggc_add_root (&function_eh_regions, 1, sizeof (function_eh_regions),
2669 mark_func_eh_entry);
2672 /* Initialize the per-function EH information. */
2675 init_eh_for_function ()
2677 cfun->eh = (struct eh_status *) xcalloc (1, sizeof (struct eh_status));
2678 ehqueue = (struct eh_queue *) xcalloc (1, sizeof (struct eh_queue));
2679 eh_return_context = NULL_RTX;
2680 eh_return_stack_adjust = NULL_RTX;
2681 eh_return_handler = NULL_RTX;
2688 free (f->eh->x_ehqueue);
2693 /* This section is for the exception handling specific optimization
2696 /* Determine if the given INSN can throw an exception. */
2702 if (GET_CODE (insn) == INSN
2703 && GET_CODE (PATTERN (insn)) == SEQUENCE)
2704 insn = XVECEXP (PATTERN (insn), 0, 0);
2706 /* Calls can always potentially throw exceptions, unless they have
2707 a REG_EH_REGION note with a value of 0 or less. */
2708 if (GET_CODE (insn) == CALL_INSN)
2710 rtx note = find_reg_note (insn, REG_EH_REGION, NULL_RTX);
2711 if (!note || INTVAL (XEXP (note, 0)) > 0)
2715 if (asynchronous_exceptions)
2717 /* If we wanted asynchronous exceptions, then everything but NOTEs
2718 and CODE_LABELs could throw. */
2719 if (GET_CODE (insn) != NOTE && GET_CODE (insn) != CODE_LABEL)
2726 /* Return nonzero if nothing in this function can throw. */
2729 nothrow_function_p ()
2733 if (! flag_exceptions)
2736 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
2737 if (can_throw (insn))
2739 for (insn = current_function_epilogue_delay_list; insn;
2740 insn = XEXP (insn, 1))
2741 if (can_throw (insn))
2747 /* Scan a exception region looking for the matching end and then
2748 remove it if possible. INSN is the start of the region, N is the
2749 region number, and DELETE_OUTER is to note if anything in this
2752 Regions are removed if they cannot possibly catch an exception.
2753 This is determined by invoking can_throw on each insn within the
2754 region; if can_throw returns true for any of the instructions, the
2755 region can catch an exception, since there is an insn within the
2756 region that is capable of throwing an exception.
2758 Returns the NOTE_INSN_EH_REGION_END corresponding to this region, or
2759 calls abort if it can't find one.
2761 Can abort if INSN is not a NOTE_INSN_EH_REGION_BEGIN, or if N doesn't
2762 correspond to the region number, or if DELETE_OUTER is NULL. */
2765 scan_region (insn, n, delete_outer)
2772 /* Assume we can delete the region. */
2775 /* Can't delete something which is rethrown from. */
2776 if (rethrow_used (n))
2779 if (insn == NULL_RTX
2780 || GET_CODE (insn) != NOTE
2781 || NOTE_LINE_NUMBER (insn) != NOTE_INSN_EH_REGION_BEG
2782 || NOTE_EH_HANDLER (insn) != n
2783 || delete_outer == NULL)
2786 insn = NEXT_INSN (insn);
2788 /* Look for the matching end. */
2789 while (! (GET_CODE (insn) == NOTE
2790 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_END))
2792 /* If anything can throw, we can't remove the region. */
2793 if (delete && can_throw (insn))
2798 /* Watch out for and handle nested regions. */
2799 if (GET_CODE (insn) == NOTE
2800 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG)
2802 insn = scan_region (insn, NOTE_EH_HANDLER (insn), &delete);
2805 insn = NEXT_INSN (insn);
2808 /* The _BEG/_END NOTEs must match and nest. */
2809 if (NOTE_EH_HANDLER (insn) != n)
2812 /* If anything in this exception region can throw, we can throw. */
2817 /* Delete the start and end of the region. */
2818 delete_insn (start);
2821 /* We no longer removed labels here, since flow will now remove any
2822 handler which cannot be called any more. */
2825 /* Only do this part if we have built the exception handler
2827 if (exception_handler_labels)
2829 rtx x, *prev = &exception_handler_labels;
2831 /* Find it in the list of handlers. */
2832 for (x = exception_handler_labels; x; x = XEXP (x, 1))
2834 rtx label = XEXP (x, 0);
2835 if (CODE_LABEL_NUMBER (label) == n)
2837 /* If we are the last reference to the handler,
2839 if (--LABEL_NUSES (label) == 0)
2840 delete_insn (label);
2844 /* Remove it from the list of exception handler
2845 labels, if we are optimizing. If we are not, then
2846 leave it in the list, as we are not really going to
2847 remove the region. */
2848 *prev = XEXP (x, 1);
2855 prev = &XEXP (x, 1);
2863 /* Perform various interesting optimizations for exception handling
2866 We look for empty exception regions and make them go (away). The
2867 jump optimization code will remove the handler if nothing else uses
2871 exception_optimize ()
2876 /* Remove empty regions. */
2877 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
2879 if (GET_CODE (insn) == NOTE
2880 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG)
2882 /* Since scan_region will return the NOTE_INSN_EH_REGION_END
2883 insn, we will indirectly skip through all the insns
2884 inbetween. We are also guaranteed that the value of insn
2885 returned will be valid, as otherwise scan_region won't
2887 insn = scan_region (insn, NOTE_EH_HANDLER (insn), &n);
2892 /* This function determines whether the rethrow labels for any of the
2893 exception regions in the current function are used or not, and set
2894 the reference flag according. */
2897 update_rethrow_references ()
2901 int *saw_region, *saw_rethrow;
2903 if (!flag_new_exceptions)
2906 saw_region = (int *) xcalloc (current_func_eh_entry, sizeof (int));
2907 saw_rethrow = (int *) xcalloc (current_func_eh_entry, sizeof (int));
2909 /* Determine what regions exist, and whether there are any rethrows
2910 from those regions or not. */
2911 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
2912 if (GET_CODE (insn) == CALL_INSN)
2914 rtx note = find_reg_note (insn, REG_EH_RETHROW, NULL_RTX);
2917 region = eh_region_from_symbol (XEXP (note, 0));
2918 region = find_func_region (region);
2919 saw_rethrow[region] = 1;
2923 if (GET_CODE (insn) == NOTE)
2925 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG)
2927 region = find_func_region (NOTE_EH_HANDLER (insn));
2928 saw_region[region] = 1;
2932 /* For any regions we did see, set the referenced flag. */
2933 for (x = 0; x < current_func_eh_entry; x++)
2935 function_eh_regions[x].rethrow_ref = saw_rethrow[x];
2942 /* Various hooks for the DWARF 2 __throw routine. */
2944 /* Do any necessary initialization to access arbitrary stack frames.
2945 On the SPARC, this means flushing the register windows. */
2948 expand_builtin_unwind_init ()
2950 /* Set this so all the registers get saved in our frame; we need to be
2951 able to copy the saved values for any registers from frames we unwind. */
2952 current_function_has_nonlocal_label = 1;
2954 #ifdef SETUP_FRAME_ADDRESSES
2955 SETUP_FRAME_ADDRESSES ();
2959 /* Given a value extracted from the return address register or stack slot,
2960 return the actual address encoded in that value. */
2963 expand_builtin_extract_return_addr (addr_tree)
2966 rtx addr = expand_expr (addr_tree, NULL_RTX, Pmode, 0);
2967 return eh_outer_context (addr);
2970 /* Given an actual address in addr_tree, do any necessary encoding
2971 and return the value to be stored in the return address register or
2972 stack slot so the epilogue will return to that address. */
2975 expand_builtin_frob_return_addr (addr_tree)
2978 rtx addr = expand_expr (addr_tree, NULL_RTX, Pmode, 0);
2979 #ifdef RETURN_ADDR_OFFSET
2980 addr = plus_constant (addr, -RETURN_ADDR_OFFSET);
2985 /* Choose three registers for communication between the main body of
2986 __throw and the epilogue (or eh stub) and the exception handler.
2987 We must do this with hard registers because the epilogue itself
2988 will be generated after reload, at which point we may not reference
2991 The first passes the exception context to the handler. For this
2992 we use the return value register for a void*.
2994 The second holds the stack pointer value to be restored. For this
2995 we use the static chain register if it exists, is different from
2996 the previous, and is call-clobbered; otherwise some arbitrary
2997 call-clobbered register.
2999 The third holds the address of the handler itself. Here we use
3000 some arbitrary call-clobbered register. */
3003 eh_regs (pcontext, psp, pra, outgoing)
3004 rtx *pcontext, *psp, *pra;
3005 int outgoing ATTRIBUTE_UNUSED;
3007 rtx rcontext, rsp, rra;
3010 #ifdef FUNCTION_OUTGOING_VALUE
3012 rcontext = FUNCTION_OUTGOING_VALUE (build_pointer_type (void_type_node),
3013 current_function_decl);
3016 rcontext = FUNCTION_VALUE (build_pointer_type (void_type_node),
3017 current_function_decl);
3019 #ifdef STATIC_CHAIN_REGNUM
3021 rsp = static_chain_incoming_rtx;
3023 rsp = static_chain_rtx;
3024 if (REGNO (rsp) == REGNO (rcontext)
3025 || ! call_used_regs [REGNO (rsp)])
3026 #endif /* STATIC_CHAIN_REGNUM */
3029 if (rsp == NULL_RTX)
3031 for (i = 0; i < FIRST_PSEUDO_REGISTER; ++i)
3032 if (call_used_regs[i] && ! fixed_regs[i] && i != REGNO (rcontext))
3034 if (i == FIRST_PSEUDO_REGISTER)
3037 rsp = gen_rtx_REG (Pmode, i);
3040 for (i = 0; i < FIRST_PSEUDO_REGISTER; ++i)
3041 if (call_used_regs[i] && ! fixed_regs[i]
3042 && i != REGNO (rcontext) && i != REGNO (rsp))
3044 if (i == FIRST_PSEUDO_REGISTER)
3047 rra = gen_rtx_REG (Pmode, i);
3049 *pcontext = rcontext;
3054 /* Retrieve the register which contains the pointer to the eh_context
3055 structure set the __throw. */
3059 get_reg_for_handler ()
3062 reg1 = FUNCTION_VALUE (build_pointer_type (void_type_node),
3063 current_function_decl);
3068 /* Set up the epilogue with the magic bits we'll need to return to the
3069 exception handler. */
3072 expand_builtin_eh_return (context, stack, handler)
3073 tree context, stack, handler;
3075 if (eh_return_context)
3076 error("Duplicate call to __builtin_eh_return");
3079 = copy_to_reg (expand_expr (context, NULL_RTX, VOIDmode, 0));
3080 eh_return_stack_adjust
3081 = copy_to_reg (expand_expr (stack, NULL_RTX, VOIDmode, 0));
3083 = copy_to_reg (expand_expr (handler, NULL_RTX, VOIDmode, 0));
3089 rtx reg1, reg2, reg3;
3090 rtx stub_start, after_stub;
3093 if (!eh_return_context)
3096 current_function_cannot_inline = N_("function uses __builtin_eh_return");
3098 eh_regs (®1, ®2, ®3, 1);
3099 #ifdef POINTERS_EXTEND_UNSIGNED
3100 eh_return_context = convert_memory_address (Pmode, eh_return_context);
3101 eh_return_stack_adjust =
3102 convert_memory_address (Pmode, eh_return_stack_adjust);
3103 eh_return_handler = convert_memory_address (Pmode, eh_return_handler);
3105 emit_move_insn (reg1, eh_return_context);
3106 emit_move_insn (reg2, eh_return_stack_adjust);
3107 emit_move_insn (reg3, eh_return_handler);
3109 /* Talk directly to the target's epilogue code when possible. */
3111 #ifdef HAVE_eh_epilogue
3112 if (HAVE_eh_epilogue)
3114 emit_insn (gen_eh_epilogue (reg1, reg2, reg3));
3119 /* Otherwise, use the same stub technique we had before. */
3121 eh_return_stub_label = stub_start = gen_label_rtx ();
3122 after_stub = gen_label_rtx ();
3124 /* Set the return address to the stub label. */
3126 ra = expand_builtin_return_addr (BUILT_IN_RETURN_ADDRESS,
3127 0, hard_frame_pointer_rtx);
3128 if (GET_CODE (ra) == REG && REGNO (ra) >= FIRST_PSEUDO_REGISTER)
3131 tmp = memory_address (Pmode, gen_rtx_LABEL_REF (Pmode, stub_start));
3132 #ifdef RETURN_ADDR_OFFSET
3133 tmp = plus_constant (tmp, -RETURN_ADDR_OFFSET);
3135 tmp = force_operand (tmp, ra);
3137 emit_move_insn (ra, tmp);
3139 /* Indicate that the registers are in fact used. */
3140 emit_insn (gen_rtx_USE (VOIDmode, reg1));
3141 emit_insn (gen_rtx_USE (VOIDmode, reg2));
3142 emit_insn (gen_rtx_USE (VOIDmode, reg3));
3143 if (GET_CODE (ra) == REG)
3144 emit_insn (gen_rtx_USE (VOIDmode, ra));
3146 /* Generate the stub. */
3148 emit_jump (after_stub);
3149 emit_label (stub_start);
3151 eh_regs (®1, ®2, ®3, 0);
3152 adjust_stack (reg2);
3153 emit_indirect_jump (reg3);
3155 emit_label (after_stub);
3159 /* This contains the code required to verify whether arbitrary instructions
3160 are in the same exception region. */
3162 static int *insn_eh_region = (int *)0;
3163 static int maximum_uid;
3166 set_insn_eh_region (first, region_num)
3173 for (insn = *first; insn; insn = NEXT_INSN (insn))
3175 if ((GET_CODE (insn) == NOTE)
3176 && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG))
3178 rnum = NOTE_EH_HANDLER (insn);
3179 insn_eh_region[INSN_UID (insn)] = rnum;
3180 insn = NEXT_INSN (insn);
3181 set_insn_eh_region (&insn, rnum);
3182 /* Upon return, insn points to the EH_REGION_END of nested region */
3185 insn_eh_region[INSN_UID (insn)] = region_num;
3186 if ((GET_CODE (insn) == NOTE) &&
3187 (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_END))
3193 /* Free the insn table, an make sure it cannot be used again. */
3196 free_insn_eh_region ()
3203 free (insn_eh_region);
3204 insn_eh_region = (int *)0;
3208 /* Initialize the table. max_uid must be calculated and handed into
3209 this routine. If it is unavailable, passing a value of 0 will
3210 cause this routine to calculate it as well. */
3213 init_insn_eh_region (first, max_uid)
3223 free_insn_eh_region();
3226 for (insn = first; insn; insn = NEXT_INSN (insn))
3227 if (INSN_UID (insn) > max_uid) /* find largest UID */
3228 max_uid = INSN_UID (insn);
3230 maximum_uid = max_uid;
3231 insn_eh_region = (int *) xmalloc ((max_uid + 1) * sizeof (int));
3233 set_insn_eh_region (&insn, 0);
3237 /* Check whether 2 instructions are within the same region. */
3240 in_same_eh_region (insn1, insn2)
3243 int ret, uid1, uid2;
3245 /* If no exceptions, instructions are always in same region. */
3249 /* If the table isn't allocated, assume the worst. */
3250 if (!insn_eh_region)
3253 uid1 = INSN_UID (insn1);
3254 uid2 = INSN_UID (insn2);
3256 /* if instructions have been allocated beyond the end, either
3257 the table is out of date, or this is a late addition, or
3258 something... Assume the worst. */
3259 if (uid1 > maximum_uid || uid2 > maximum_uid)
3262 ret = (insn_eh_region[uid1] == insn_eh_region[uid2]);
3267 /* This function will initialize the handler list for a specified block.
3268 It may recursively call itself if the outer block hasn't been processed
3269 yet. At some point in the future we can trim out handlers which we
3270 know cannot be called. (ie, if a block has an INT type handler,
3271 control will never be passed to an outer INT type handler). */
3274 process_nestinfo (block, info, nested_eh_region)
3276 eh_nesting_info *info;
3277 int *nested_eh_region;
3279 handler_info *ptr, *last_ptr = NULL;
3280 int x, y, count = 0;
3282 handler_info **extra_handlers = 0;
3283 int index = info->region_index[block];
3285 /* If we've already processed this block, simply return. */
3286 if (info->num_handlers[index] > 0)
3289 for (ptr = get_first_handler (block); ptr; last_ptr = ptr, ptr = ptr->next)
3292 /* pick up any information from the next outer region. It will already
3293 contain a summary of itself and all outer regions to it. */
3295 if (nested_eh_region [block] != 0)
3297 int nested_index = info->region_index[nested_eh_region[block]];
3298 process_nestinfo (nested_eh_region[block], info, nested_eh_region);
3299 extra = info->num_handlers[nested_index];
3300 extra_handlers = info->handlers[nested_index];
3301 info->outer_index[index] = nested_index;
3304 /* If the last handler is either a CATCH_ALL or a cleanup, then we
3305 won't use the outer ones since we know control will not go past the
3306 catch-all or cleanup. */
3308 if (last_ptr != NULL && (last_ptr->type_info == NULL
3309 || last_ptr->type_info == CATCH_ALL_TYPE))
3312 info->num_handlers[index] = count + extra;
3313 info->handlers[index] = (handler_info **) xmalloc ((count + extra)
3314 * sizeof (handler_info **));
3316 /* First put all our handlers into the list. */
3317 ptr = get_first_handler (block);
3318 for (x = 0; x < count; x++)
3320 info->handlers[index][x] = ptr;
3324 /* Now add all the outer region handlers, if they aren't they same as
3325 one of the types in the current block. We won't worry about
3326 derived types yet, we'll just look for the exact type. */
3327 for (y =0, x = 0; x < extra ; x++)
3331 /* Check to see if we have a type duplication. */
3332 for (i = 0; i < count; i++)
3333 if (info->handlers[index][i]->type_info == extra_handlers[x]->type_info)
3336 /* Record one less handler. */
3337 (info->num_handlers[index])--;
3342 info->handlers[index][y + count] = extra_handlers[x];
3348 /* This function will allocate and initialize an eh_nesting_info structure.
3349 It returns a pointer to the completed data structure. If there are
3350 no exception regions, a NULL value is returned. */
3353 init_eh_nesting_info ()
3355 int *nested_eh_region;
3356 int region_count = 0;
3357 rtx eh_note = NULL_RTX;
3358 eh_nesting_info *info;
3362 if (! flag_exceptions)
3365 info = (eh_nesting_info *) xmalloc (sizeof (eh_nesting_info));
3366 info->region_index = (int *) xcalloc ((max_label_num () + 1), sizeof (int));
3367 nested_eh_region = (int *) xcalloc (max_label_num () + 1, sizeof (int));
3369 /* Create the nested_eh_region list. If indexed with a block number, it
3370 returns the block number of the next outermost region, if any.
3371 We can count the number of regions and initialize the region_index
3372 vector at the same time. */
3373 for (insn = get_insns(); insn; insn = NEXT_INSN (insn))
3375 if (GET_CODE (insn) == NOTE)
3377 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG)
3379 int block = NOTE_EH_HANDLER (insn);
3381 info->region_index[block] = region_count;
3383 nested_eh_region [block] =
3384 NOTE_EH_HANDLER (XEXP (eh_note, 0));
3386 nested_eh_region [block] = 0;
3387 eh_note = gen_rtx_EXPR_LIST (VOIDmode, insn, eh_note);
3389 else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_END)
3390 eh_note = XEXP (eh_note, 1);
3394 /* If there are no regions, wrap it up now. */
3395 if (region_count == 0)
3397 free (info->region_index);
3399 free (nested_eh_region);
3404 info->handlers = (handler_info ***) xcalloc (region_count,
3405 sizeof (handler_info ***));
3406 info->num_handlers = (int *) xcalloc (region_count, sizeof (int));
3407 info->outer_index = (int *) xcalloc (region_count, sizeof (int));
3409 /* Now initialize the handler lists for all exception blocks. */
3410 for (x = 0; x <= max_label_num (); x++)
3412 if (info->region_index[x] != 0)
3413 process_nestinfo (x, info, nested_eh_region);
3415 info->region_count = region_count;
3418 free (nested_eh_region);
3424 /* This function is used to retreive the vector of handlers which
3425 can be reached by a given insn in a given exception region.
3426 BLOCK is the exception block the insn is in.
3427 INFO is the eh_nesting_info structure.
3428 INSN is the (optional) insn within the block. If insn is not NULL_RTX,
3429 it may contain reg notes which modify its throwing behavior, and
3430 these will be obeyed. If NULL_RTX is passed, then we simply return the
3432 HANDLERS is the address of a pointer to a vector of handler_info pointers.
3433 Upon return, this will have the handlers which can be reached by block.
3434 This function returns the number of elements in the handlers vector. */
3437 reachable_handlers (block, info, insn, handlers)
3439 eh_nesting_info *info;
3441 handler_info ***handlers;
3449 index = info->region_index[block];
3451 if (insn && GET_CODE (insn) == CALL_INSN)
3453 /* RETHROWs specify a region number from which we are going to rethrow.
3454 This means we won't pass control to handlers in the specified
3455 region, but rather any region OUTSIDE the specified region.
3456 We accomplish this by setting block to the outer_index of the
3457 specified region. */
3458 rtx note = find_reg_note (insn, REG_EH_RETHROW, NULL_RTX);
3461 index = eh_region_from_symbol (XEXP (note, 0));
3462 index = info->region_index[index];
3464 index = info->outer_index[index];
3468 /* If there is no rethrow, we look for a REG_EH_REGION, and
3469 we'll throw from that block. A value of 0 or less
3470 indicates that this insn cannot throw. */
3471 note = find_reg_note (insn, REG_EH_REGION, NULL_RTX);
3474 int b = INTVAL (XEXP (note, 0));
3478 index = info->region_index[b];
3482 /* If we reach this point, and index is 0, there is no throw. */
3486 *handlers = info->handlers[index];
3487 return info->num_handlers[index];
3491 /* This function will free all memory associated with the eh_nesting info. */
3494 free_eh_nesting_info (info)
3495 eh_nesting_info *info;
3500 if (info->region_index)
3501 free (info->region_index);
3502 if (info->num_handlers)
3503 free (info->num_handlers);
3504 if (info->outer_index)
3505 free (info->outer_index);
3508 for (x = 0; x < info->region_count; x++)
3509 if (info->handlers[x])
3510 free (info->handlers[x]);
3511 free (info->handlers);