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 free (function_eh_regions);
935 num_func_eh_entries = 0;
936 current_func_eh_entry = 0;
939 /* Make a duplicate of an exception region by copying all the handlers
940 for an exception region. Return the new handler index. The final
941 parameter is a routine which maps old labels to new ones. */
944 duplicate_eh_handlers (old_note_eh_region, new_note_eh_region, map)
945 int old_note_eh_region, new_note_eh_region;
946 rtx (*map) PARAMS ((rtx));
948 struct handler_info *ptr, *new_ptr;
949 int new_region, region;
951 region = find_func_region (old_note_eh_region);
953 fatal ("Cannot duplicate non-existant exception region.");
955 /* duplicate_eh_handlers may have been called during a symbol remap. */
956 new_region = find_func_region (new_note_eh_region);
957 if (new_region != -1)
960 new_region = new_eh_region_entry (new_note_eh_region, NULL_RTX);
962 ptr = function_eh_regions[region].handlers;
964 for ( ; ptr; ptr = ptr->next)
966 new_ptr = get_new_handler (map (ptr->handler_label), ptr->type_info);
967 add_new_handler (new_region, new_ptr);
974 /* Given a rethrow symbol, find the EH region number this is for. */
977 eh_region_from_symbol (sym)
981 if (sym == last_rethrow_symbol)
983 for (x = 0; x < current_func_eh_entry; x++)
984 if (function_eh_regions[x].rethrow_label == sym)
985 return function_eh_regions[x].range_number;
989 /* Like find_func_region, but using the rethrow symbol for the region
990 rather than the region number itself. */
993 find_func_region_from_symbol (sym)
996 return find_func_region (eh_region_from_symbol (sym));
999 /* When inlining/unrolling, we have to map the symbols passed to
1000 __rethrow as well. This performs the remap. If a symbol isn't foiund,
1001 the original one is returned. This is not an efficient routine,
1002 so don't call it on everything!! */
1005 rethrow_symbol_map (sym, map)
1007 rtx (*map) PARAMS ((rtx));
1011 if (! flag_new_exceptions)
1014 for (x = 0; x < current_func_eh_entry; x++)
1015 if (function_eh_regions[x].rethrow_label == sym)
1017 /* We've found the original region, now lets determine which region
1018 this now maps to. */
1019 rtx l1 = function_eh_regions[x].handlers->handler_label;
1021 y = CODE_LABEL_NUMBER (l2); /* This is the new region number */
1022 x = find_func_region (y); /* Get the new permanent region */
1023 if (x == -1) /* Hmm, Doesn't exist yet */
1025 x = duplicate_eh_handlers (CODE_LABEL_NUMBER (l1), y, map);
1026 /* Since we're mapping it, it must be used. */
1027 function_eh_regions[x].rethrow_ref = 1;
1029 return function_eh_regions[x].rethrow_label;
1034 /* Returns nonzero if the rethrow label for REGION is referenced
1035 somewhere (i.e. we rethrow out of REGION or some other region
1036 masquerading as REGION). */
1039 rethrow_used (region)
1042 if (flag_new_exceptions)
1044 int ret = function_eh_regions[find_func_region (region)].rethrow_ref;
1051 /* Routine to see if exception handling is turned on.
1052 DO_WARN is non-zero if we want to inform the user that exception
1053 handling is turned off.
1055 This is used to ensure that -fexceptions has been specified if the
1056 compiler tries to use any exception-specific functions. */
1062 if (! flag_exceptions)
1064 static int warned = 0;
1065 if (! warned && do_warn)
1067 error ("exception handling disabled, use -fexceptions to enable");
1075 /* Given a return address in ADDR, determine the address we should use
1076 to find the corresponding EH region. */
1079 eh_outer_context (addr)
1082 /* First mask out any unwanted bits. */
1083 #ifdef MASK_RETURN_ADDR
1084 expand_and (addr, MASK_RETURN_ADDR, addr);
1087 /* Then adjust to find the real return address. */
1088 #if defined (RETURN_ADDR_OFFSET)
1089 addr = plus_constant (addr, RETURN_ADDR_OFFSET);
1095 /* Start a new exception region for a region of code that has a
1096 cleanup action and push the HANDLER for the region onto
1097 protect_list. All of the regions created with add_partial_entry
1098 will be ended when end_protect_partials is invoked. */
1101 add_partial_entry (handler)
1104 expand_eh_region_start ();
1106 /* Make sure the entry is on the correct obstack. */
1107 push_obstacks_nochange ();
1108 resume_temporary_allocation ();
1110 /* Because this is a cleanup action, we may have to protect the handler
1111 with __terminate. */
1112 handler = protect_with_terminate (handler);
1114 /* For backwards compatibility, we allow callers to omit calls to
1115 begin_protect_partials for the outermost region. So, we must
1116 explicitly do so here. */
1118 begin_protect_partials ();
1120 /* Add this entry to the front of the list. */
1121 TREE_VALUE (protect_list)
1122 = tree_cons (NULL_TREE, handler, TREE_VALUE (protect_list));
1126 /* Emit code to get EH context to current function. */
1129 call_get_eh_context ()
1134 if (fn == NULL_TREE)
1137 fn = get_identifier ("__get_eh_context");
1138 push_obstacks_nochange ();
1139 end_temporary_allocation ();
1140 fntype = build_pointer_type (build_pointer_type
1141 (build_pointer_type (void_type_node)));
1142 fntype = build_function_type (fntype, NULL_TREE);
1143 fn = build_decl (FUNCTION_DECL, fn, fntype);
1144 DECL_EXTERNAL (fn) = 1;
1145 TREE_PUBLIC (fn) = 1;
1146 DECL_ARTIFICIAL (fn) = 1;
1147 TREE_READONLY (fn) = 1;
1148 make_decl_rtl (fn, NULL_PTR, 1);
1149 assemble_external (fn);
1152 ggc_add_tree_root (&fn, 1);
1155 expr = build1 (ADDR_EXPR, build_pointer_type (TREE_TYPE (fn)), fn);
1156 expr = build (CALL_EXPR, TREE_TYPE (TREE_TYPE (fn)),
1157 expr, NULL_TREE, NULL_TREE);
1158 TREE_SIDE_EFFECTS (expr) = 1;
1160 return copy_to_reg (expand_expr (expr, NULL_RTX, VOIDmode, 0));
1163 /* Get a reference to the EH context.
1164 We will only generate a register for the current function EH context here,
1165 and emit a USE insn to mark that this is a EH context register.
1167 Later, emit_eh_context will emit needed call to __get_eh_context
1168 in libgcc2, and copy the value to the register we have generated. */
1173 if (current_function_ehc == 0)
1177 current_function_ehc = gen_reg_rtx (Pmode);
1179 insn = gen_rtx_USE (GET_MODE (current_function_ehc),
1180 current_function_ehc);
1181 insn = emit_insn_before (insn, get_first_nonparm_insn ());
1184 = gen_rtx_EXPR_LIST (REG_EH_CONTEXT, current_function_ehc,
1187 return current_function_ehc;
1190 /* Get a reference to the dynamic handler chain. It points to the
1191 pointer to the next element in the dynamic handler chain. It ends
1192 when there are no more elements in the dynamic handler chain, when
1193 the value is &top_elt from libgcc2.c. Immediately after the
1194 pointer, is an area suitable for setjmp/longjmp when
1195 DONT_USE_BUILTIN_SETJMP is defined, and an area suitable for
1196 __builtin_setjmp/__builtin_longjmp when DONT_USE_BUILTIN_SETJMP
1200 get_dynamic_handler_chain ()
1202 rtx ehc, dhc, result;
1204 ehc = get_eh_context ();
1206 /* This is the offset of dynamic_handler_chain in the eh_context struct
1207 declared in eh-common.h. If its location is change, change this offset */
1208 dhc = plus_constant (ehc, POINTER_SIZE / BITS_PER_UNIT);
1210 result = copy_to_reg (dhc);
1212 /* We don't want a copy of the dcc, but rather, the single dcc. */
1213 return gen_rtx_MEM (Pmode, result);
1216 /* Get a reference to the dynamic cleanup chain. It points to the
1217 pointer to the next element in the dynamic cleanup chain.
1218 Immediately after the pointer, are two Pmode variables, one for a
1219 pointer to a function that performs the cleanup action, and the
1220 second, the argument to pass to that function. */
1223 get_dynamic_cleanup_chain ()
1225 rtx dhc, dcc, result;
1227 dhc = get_dynamic_handler_chain ();
1228 dcc = plus_constant (dhc, POINTER_SIZE / BITS_PER_UNIT);
1230 result = copy_to_reg (dcc);
1232 /* We don't want a copy of the dcc, but rather, the single dcc. */
1233 return gen_rtx_MEM (Pmode, result);
1236 #ifdef DONT_USE_BUILTIN_SETJMP
1237 /* Generate code to evaluate X and jump to LABEL if the value is nonzero.
1238 LABEL is an rtx of code CODE_LABEL, in this function. */
1241 jumpif_rtx (x, label)
1245 jumpif (make_tree (type_for_mode (GET_MODE (x), 0), x), label);
1249 /* Start a dynamic cleanup on the EH runtime dynamic cleanup stack.
1250 We just need to create an element for the cleanup list, and push it
1253 A dynamic cleanup is a cleanup action implied by the presence of an
1254 element on the EH runtime dynamic cleanup stack that is to be
1255 performed when an exception is thrown. The cleanup action is
1256 performed by __sjthrow when an exception is thrown. Only certain
1257 actions can be optimized into dynamic cleanup actions. For the
1258 restrictions on what actions can be performed using this routine,
1259 see expand_eh_region_start_tree. */
1262 start_dynamic_cleanup (func, arg)
1267 rtx new_func, new_arg;
1271 /* We allocate enough room for a pointer to the function, and
1275 /* XXX, FIXME: The stack space allocated this way is too long lived,
1276 but there is no allocation routine that allocates at the level of
1277 the last binding contour. */
1278 buf = assign_stack_local (BLKmode,
1279 GET_MODE_SIZE (Pmode)*(size+1),
1282 buf = change_address (buf, Pmode, NULL_RTX);
1284 /* Store dcc into the first word of the newly allocated buffer. */
1286 dcc = get_dynamic_cleanup_chain ();
1287 emit_move_insn (buf, dcc);
1289 /* Store func and arg into the cleanup list element. */
1291 new_func = gen_rtx_MEM (Pmode, plus_constant (XEXP (buf, 0),
1292 GET_MODE_SIZE (Pmode)));
1293 new_arg = gen_rtx_MEM (Pmode, plus_constant (XEXP (buf, 0),
1294 GET_MODE_SIZE (Pmode)*2));
1295 x = expand_expr (func, new_func, Pmode, 0);
1297 emit_move_insn (new_func, x);
1299 x = expand_expr (arg, new_arg, Pmode, 0);
1301 emit_move_insn (new_arg, x);
1303 /* Update the cleanup chain. */
1305 x = force_operand (XEXP (buf, 0), dcc);
1307 emit_move_insn (dcc, x);
1310 /* Emit RTL to start a dynamic handler on the EH runtime dynamic
1311 handler stack. This should only be used by expand_eh_region_start
1312 or expand_eh_region_start_tree. */
1315 start_dynamic_handler ()
1321 #ifndef DONT_USE_BUILTIN_SETJMP
1322 /* The number of Pmode words for the setjmp buffer, when using the
1323 builtin setjmp/longjmp, see expand_builtin, case BUILT_IN_LONGJMP. */
1324 /* We use 2 words here before calling expand_builtin_setjmp.
1325 expand_builtin_setjmp uses 2 words, and then calls emit_stack_save.
1326 emit_stack_save needs space of size STACK_SAVEAREA_MODE (SAVE_NONLOCAL).
1327 Subtract one, because the assign_stack_local call below adds 1. */
1328 size = (2 + 2 + (GET_MODE_SIZE (STACK_SAVEAREA_MODE (SAVE_NONLOCAL))
1329 / GET_MODE_SIZE (Pmode))
1333 size = JMP_BUF_SIZE;
1335 /* Should be large enough for most systems, if it is not,
1336 JMP_BUF_SIZE should be defined with the proper value. It will
1337 also tend to be larger than necessary for most systems, a more
1338 optimal port will define JMP_BUF_SIZE. */
1339 size = FIRST_PSEUDO_REGISTER+2;
1342 /* XXX, FIXME: The stack space allocated this way is too long lived,
1343 but there is no allocation routine that allocates at the level of
1344 the last binding contour. */
1345 arg = assign_stack_local (BLKmode,
1346 GET_MODE_SIZE (Pmode)*(size+1),
1349 arg = change_address (arg, Pmode, NULL_RTX);
1351 /* Store dhc into the first word of the newly allocated buffer. */
1353 dhc = get_dynamic_handler_chain ();
1354 dcc = gen_rtx_MEM (Pmode, plus_constant (XEXP (arg, 0),
1355 GET_MODE_SIZE (Pmode)));
1356 emit_move_insn (arg, dhc);
1358 /* Zero out the start of the cleanup chain. */
1359 emit_move_insn (dcc, const0_rtx);
1361 /* The jmpbuf starts two words into the area allocated. */
1362 buf = plus_constant (XEXP (arg, 0), GET_MODE_SIZE (Pmode)*2);
1364 #ifdef DONT_USE_BUILTIN_SETJMP
1365 x = emit_library_call_value (setjmp_libfunc, NULL_RTX, 1,
1366 TYPE_MODE (integer_type_node), 1,
1368 /* If we come back here for a catch, transfer control to the handler. */
1369 jumpif_rtx (x, ehstack.top->entry->exception_handler_label);
1372 /* A label to continue execution for the no exception case. */
1373 rtx noex = gen_label_rtx();
1374 x = expand_builtin_setjmp (buf, NULL_RTX, noex,
1375 ehstack.top->entry->exception_handler_label);
1380 /* We are committed to this, so update the handler chain. */
1382 emit_move_insn (dhc, force_operand (XEXP (arg, 0), NULL_RTX));
1385 /* Start an exception handling region for the given cleanup action.
1386 All instructions emitted after this point are considered to be part
1387 of the region until expand_eh_region_end is invoked. CLEANUP is
1388 the cleanup action to perform. The return value is true if the
1389 exception region was optimized away. If that case,
1390 expand_eh_region_end does not need to be called for this cleanup,
1393 This routine notices one particular common case in C++ code
1394 generation, and optimizes it so as to not need the exception
1395 region. It works by creating a dynamic cleanup action, instead of
1396 a using an exception region. */
1399 expand_eh_region_start_tree (decl, cleanup)
1403 /* This is the old code. */
1407 /* The optimization only applies to actions protected with
1408 terminate, and only applies if we are using the setjmp/longjmp
1410 if (exceptions_via_longjmp
1411 && protect_cleanup_actions_with_terminate)
1416 /* Ignore any UNSAVE_EXPR. */
1417 if (TREE_CODE (cleanup) == UNSAVE_EXPR)
1418 cleanup = TREE_OPERAND (cleanup, 0);
1420 /* Further, it only applies if the action is a call, if there
1421 are 2 arguments, and if the second argument is 2. */
1423 if (TREE_CODE (cleanup) == CALL_EXPR
1424 && (args = TREE_OPERAND (cleanup, 1))
1425 && (func = TREE_OPERAND (cleanup, 0))
1426 && (arg = TREE_VALUE (args))
1427 && (args = TREE_CHAIN (args))
1429 /* is the second argument 2? */
1430 && TREE_CODE (TREE_VALUE (args)) == INTEGER_CST
1431 && compare_tree_int (TREE_VALUE (args), 2) == 0
1433 /* Make sure there are no other arguments. */
1434 && TREE_CHAIN (args) == NULL_TREE)
1436 /* Arrange for returns and gotos to pop the entry we make on the
1437 dynamic cleanup stack. */
1438 expand_dcc_cleanup (decl);
1439 start_dynamic_cleanup (func, arg);
1444 expand_eh_region_start_for_decl (decl);
1445 ehstack.top->entry->finalization = cleanup;
1450 /* Just like expand_eh_region_start, except if a cleanup action is
1451 entered on the cleanup chain, the TREE_PURPOSE of the element put
1452 on the chain is DECL. DECL should be the associated VAR_DECL, if
1453 any, otherwise it should be NULL_TREE. */
1456 expand_eh_region_start_for_decl (decl)
1461 /* This is the old code. */
1465 /* We need a new block to record the start and end of the
1466 dynamic handler chain. We also want to prevent jumping into
1468 expand_start_bindings (2);
1470 /* But we don't need or want a new temporary level. */
1473 /* Mark this block as created by expand_eh_region_start. This
1474 is so that we can pop the block with expand_end_bindings
1476 mark_block_as_eh_region ();
1478 if (exceptions_via_longjmp)
1480 /* Arrange for returns and gotos to pop the entry we make on the
1481 dynamic handler stack. */
1482 expand_dhc_cleanup (decl);
1485 push_eh_entry (&ehstack);
1486 note = emit_note (NULL_PTR, NOTE_INSN_EH_REGION_BEG);
1487 NOTE_EH_HANDLER (note)
1488 = CODE_LABEL_NUMBER (ehstack.top->entry->exception_handler_label);
1489 if (exceptions_via_longjmp)
1490 start_dynamic_handler ();
1493 /* Start an exception handling region. All instructions emitted after
1494 this point are considered to be part of the region until
1495 expand_eh_region_end is invoked. */
1498 expand_eh_region_start ()
1500 expand_eh_region_start_for_decl (NULL_TREE);
1503 /* End an exception handling region. The information about the region
1504 is found on the top of ehstack.
1506 HANDLER is either the cleanup for the exception region, or if we're
1507 marking the end of a try block, HANDLER is integer_zero_node.
1509 HANDLER will be transformed to rtl when expand_leftover_cleanups
1513 expand_eh_region_end (handler)
1516 struct eh_entry *entry;
1517 struct eh_node *node;
1524 entry = pop_eh_entry (&ehstack);
1526 note = emit_note (NULL_PTR, NOTE_INSN_EH_REGION_END);
1527 ret = NOTE_EH_HANDLER (note)
1528 = CODE_LABEL_NUMBER (entry->exception_handler_label);
1529 if (exceptions_via_longjmp == 0 && ! flag_new_exceptions
1530 /* We share outer_context between regions; only emit it once. */
1531 && INSN_UID (entry->outer_context) == 0)
1535 label = gen_label_rtx ();
1538 /* Emit a label marking the end of this exception region that
1539 is used for rethrowing into the outer context. */
1540 emit_label (entry->outer_context);
1541 expand_internal_throw ();
1546 entry->finalization = handler;
1548 /* create region entry in final exception table */
1549 r = new_eh_region_entry (NOTE_EH_HANDLER (note), entry->rethrow_label);
1551 enqueue_eh_entry (ehqueue, entry);
1553 /* If we have already started ending the bindings, don't recurse. */
1554 if (is_eh_region ())
1556 /* Because we don't need or want a new temporary level and
1557 because we didn't create one in expand_eh_region_start,
1558 create a fake one now to avoid removing one in
1559 expand_end_bindings. */
1562 mark_block_as_not_eh_region ();
1564 expand_end_bindings (NULL_TREE, 0, 0);
1567 /* Go through the goto handlers in the queue, emitting their
1568 handlers if we now have enough information to do so. */
1569 for (node = ehqueue->head; node; node = node->chain)
1570 if (node->entry->goto_entry_p
1571 && node->entry->outer_context == entry->rethrow_label)
1572 emit_cleanup_handler (node->entry);
1574 /* We can't emit handlers for goto entries until their scopes are
1575 complete because we don't know where they need to rethrow to,
1577 if (entry->finalization != integer_zero_node
1578 && (!entry->goto_entry_p
1579 || find_func_region_from_symbol (entry->outer_context) != -1))
1580 emit_cleanup_handler (entry);
1583 /* End the EH region for a goto fixup. We only need them in the region-based
1587 expand_fixup_region_start ()
1589 if (! doing_eh (0) || exceptions_via_longjmp)
1592 expand_eh_region_start ();
1593 /* Mark this entry as the entry for a goto. */
1594 ehstack.top->entry->goto_entry_p = 1;
1597 /* End the EH region for a goto fixup. CLEANUP is the cleanup we just
1598 expanded; to avoid running it twice if it throws, we look through the
1599 ehqueue for a matching region and rethrow from its outer_context. */
1602 expand_fixup_region_end (cleanup)
1605 struct eh_node *node;
1608 if (! doing_eh (0) || exceptions_via_longjmp)
1611 for (node = ehstack.top; node && node->entry->finalization != cleanup; )
1614 for (node = ehqueue->head; node && node->entry->finalization != cleanup; )
1619 /* If the outer context label has not been issued yet, we don't want
1620 to issue it as a part of this region, unless this is the
1621 correct region for the outer context. If we did, then the label for
1622 the outer context will be WITHIN the begin/end labels,
1623 and we could get an infinte loop when it tried to rethrow, or just
1624 generally incorrect execution following a throw. */
1626 if (flag_new_exceptions)
1629 dont_issue = ((INSN_UID (node->entry->outer_context) == 0)
1630 && (ehstack.top->entry != node->entry));
1632 ehstack.top->entry->outer_context = node->entry->outer_context;
1634 /* Since we are rethrowing to the OUTER region, we know we don't need
1635 a jump around sequence for this region, so we'll pretend the outer
1636 context label has been issued by setting INSN_UID to 1, then clearing
1637 it again afterwards. */
1640 INSN_UID (node->entry->outer_context) = 1;
1642 /* Just rethrow. size_zero_node is just a NOP. */
1643 expand_eh_region_end (size_zero_node);
1646 INSN_UID (node->entry->outer_context) = 0;
1649 /* If we are using the setjmp/longjmp EH codegen method, we emit a
1650 call to __sjthrow. Otherwise, we emit a call to __throw. */
1655 if (exceptions_via_longjmp)
1657 emit_library_call (sjthrow_libfunc, 0, VOIDmode, 0);
1661 #ifdef JUMP_TO_THROW
1662 emit_indirect_jump (throw_libfunc);
1664 emit_library_call (throw_libfunc, 0, VOIDmode, 0);
1670 /* Throw the current exception. If appropriate, this is done by jumping
1671 to the next handler. */
1674 expand_internal_throw ()
1679 /* Called from expand_exception_blocks and expand_end_catch_block to
1680 emit any pending handlers/cleanups queued from expand_eh_region_end. */
1683 expand_leftover_cleanups ()
1685 struct eh_entry *entry;
1687 for (entry = dequeue_eh_entry (ehqueue);
1689 entry = dequeue_eh_entry (ehqueue))
1691 /* A leftover try block. Shouldn't be one here. */
1692 if (entry->finalization == integer_zero_node)
1699 /* Called at the start of a block of try statements. */
1701 expand_start_try_stmts ()
1706 expand_eh_region_start ();
1709 /* Called to begin a catch clause. The parameter is the object which
1710 will be passed to the runtime type check routine. */
1712 start_catch_handler (rtime)
1716 int insn_region_num;
1717 int eh_region_entry;
1722 handler_label = catchstack.top->entry->exception_handler_label;
1723 insn_region_num = CODE_LABEL_NUMBER (handler_label);
1724 eh_region_entry = find_func_region (insn_region_num);
1726 /* If we've already issued this label, pick a new one */
1727 if (catchstack.top->entry->label_used)
1728 handler_label = gen_exception_label ();
1730 catchstack.top->entry->label_used = 1;
1732 receive_exception_label (handler_label);
1734 add_new_handler (eh_region_entry, get_new_handler (handler_label, rtime));
1736 if (flag_new_exceptions && ! exceptions_via_longjmp)
1739 /* Under the old mechanism, as well as setjmp/longjmp, we need to
1740 issue code to compare 'rtime' to the value in eh_info, via the
1741 matching function in eh_info. If its is false, we branch around
1742 the handler we are about to issue. */
1744 if (rtime != NULL_TREE && rtime != CATCH_ALL_TYPE)
1746 rtx call_rtx, rtime_address;
1748 if (catchstack.top->entry->false_label != NULL_RTX)
1750 error ("Never issued previous false_label");
1753 catchstack.top->entry->false_label = gen_exception_label ();
1755 rtime_address = expand_expr (rtime, NULL_RTX, Pmode, EXPAND_INITIALIZER);
1756 #ifdef POINTERS_EXTEND_UNSIGNED
1757 rtime_address = convert_memory_address (Pmode, rtime_address);
1759 rtime_address = force_reg (Pmode, rtime_address);
1761 /* Now issue the call, and branch around handler if needed */
1762 call_rtx = emit_library_call_value (eh_rtime_match_libfunc, NULL_RTX,
1763 0, TYPE_MODE (integer_type_node),
1764 1, rtime_address, Pmode);
1766 /* Did the function return true? */
1767 emit_cmp_and_jump_insns (call_rtx, const0_rtx, EQ, NULL_RTX,
1768 GET_MODE (call_rtx), 0, 0,
1769 catchstack.top->entry->false_label);
1773 /* Called to end a catch clause. If we aren't using the new exception
1774 model tabel mechanism, we need to issue the branch-around label
1775 for the end of the catch block. */
1778 end_catch_handler ()
1783 if (flag_new_exceptions && ! exceptions_via_longjmp)
1789 /* A NULL label implies the catch clause was a catch all or cleanup */
1790 if (catchstack.top->entry->false_label == NULL_RTX)
1793 emit_label (catchstack.top->entry->false_label);
1794 catchstack.top->entry->false_label = NULL_RTX;
1797 /* Save away the current ehqueue. */
1803 q = (struct eh_queue *) xcalloc (1, sizeof (struct eh_queue));
1808 /* Restore a previously pushed ehqueue. */
1814 expand_leftover_cleanups ();
1820 /* Emit the handler specified by ENTRY. */
1823 emit_cleanup_handler (entry)
1824 struct eh_entry *entry;
1829 /* Since the cleanup could itself contain try-catch blocks, we
1830 squirrel away the current queue and replace it when we are done
1831 with this function. */
1834 /* Put these handler instructions in a sequence. */
1835 do_pending_stack_adjust ();
1838 /* Emit the label for the cleanup handler for this region, and
1839 expand the code for the handler.
1841 Note that a catch region is handled as a side-effect here; for a
1842 try block, entry->finalization will contain integer_zero_node, so
1843 no code will be generated in the expand_expr call below. But, the
1844 label for the handler will still be emitted, so any code emitted
1845 after this point will end up being the handler. */
1847 receive_exception_label (entry->exception_handler_label);
1849 /* register a handler for this cleanup region */
1850 add_new_handler (find_func_region (CODE_LABEL_NUMBER (entry->exception_handler_label)),
1851 get_new_handler (entry->exception_handler_label, NULL));
1853 /* And now generate the insns for the cleanup handler. */
1854 expand_expr (entry->finalization, const0_rtx, VOIDmode, 0);
1856 prev = get_last_insn ();
1857 if (prev == NULL || GET_CODE (prev) != BARRIER)
1858 /* Code to throw out to outer context when we fall off end of the
1859 handler. We can't do this here for catch blocks, so it's done
1860 in expand_end_all_catch instead. */
1861 expand_rethrow (entry->outer_context);
1863 /* Finish this sequence. */
1864 do_pending_stack_adjust ();
1865 handler_insns = get_insns ();
1868 /* And add it to the CATCH_CLAUSES. */
1869 push_to_full_sequence (catch_clauses, catch_clauses_last);
1870 emit_insns (handler_insns);
1871 end_full_sequence (&catch_clauses, &catch_clauses_last);
1873 /* Now we've left the handler. */
1877 /* Generate RTL for the start of a group of catch clauses.
1879 It is responsible for starting a new instruction sequence for the
1880 instructions in the catch block, and expanding the handlers for the
1881 internally-generated exception regions nested within the try block
1882 corresponding to this catch block. */
1885 expand_start_all_catch ()
1887 struct eh_entry *entry;
1894 outer_context = ehstack.top->entry->outer_context;
1896 /* End the try block. */
1897 expand_eh_region_end (integer_zero_node);
1899 emit_line_note (input_filename, lineno);
1900 label = build_decl (LABEL_DECL, NULL_TREE, NULL_TREE);
1902 /* The label for the exception handling block that we will save.
1903 This is Lresume in the documentation. */
1904 expand_label (label);
1906 /* Push the label that points to where normal flow is resumed onto
1907 the top of the label stack. */
1908 push_label_entry (&caught_return_label_stack, NULL_RTX, label);
1910 /* Start a new sequence for all the catch blocks. We will add this
1911 to the global sequence catch_clauses when we have completed all
1912 the handlers in this handler-seq. */
1915 /* Throw away entries in the queue that we won't need anymore. We
1916 need entries for regions that have ended but to which there might
1917 still be gotos pending. */
1918 for (entry = dequeue_eh_entry (ehqueue);
1919 entry->finalization != integer_zero_node;
1920 entry = dequeue_eh_entry (ehqueue))
1923 /* At this point, all the cleanups are done, and the ehqueue now has
1924 the current exception region at its head. We dequeue it, and put it
1925 on the catch stack. */
1926 push_entry (&catchstack, entry);
1928 /* If we are not doing setjmp/longjmp EH, because we are reordered
1929 out of line, we arrange to rethrow in the outer context. We need to
1930 do this because we are not physically within the region, if any, that
1931 logically contains this catch block. */
1932 if (! exceptions_via_longjmp)
1934 expand_eh_region_start ();
1935 ehstack.top->entry->outer_context = outer_context;
1940 /* Finish up the catch block. At this point all the insns for the
1941 catch clauses have already been generated, so we only have to add
1942 them to the catch_clauses list. We also want to make sure that if
1943 we fall off the end of the catch clauses that we rethrow to the
1947 expand_end_all_catch ()
1949 rtx new_catch_clause;
1950 struct eh_entry *entry;
1955 /* Dequeue the current catch clause region. */
1956 entry = pop_eh_entry (&catchstack);
1959 if (! exceptions_via_longjmp)
1961 rtx outer_context = ehstack.top->entry->outer_context;
1963 /* Finish the rethrow region. size_zero_node is just a NOP. */
1964 expand_eh_region_end (size_zero_node);
1965 /* New exceptions handling models will never have a fall through
1966 of a catch clause */
1967 if (!flag_new_exceptions)
1968 expand_rethrow (outer_context);
1971 expand_rethrow (NULL_RTX);
1973 /* Code to throw out to outer context, if we fall off end of catch
1974 handlers. This is rethrow (Lresume, same id, same obj) in the
1975 documentation. We use Lresume because we know that it will throw
1976 to the correct context.
1978 In other words, if the catch handler doesn't exit or return, we
1979 do a "throw" (using the address of Lresume as the point being
1980 thrown from) so that the outer EH region can then try to process
1983 /* Now we have the complete catch sequence. */
1984 new_catch_clause = get_insns ();
1987 /* This level of catch blocks is done, so set up the successful
1988 catch jump label for the next layer of catch blocks. */
1989 pop_label_entry (&caught_return_label_stack);
1990 pop_label_entry (&outer_context_label_stack);
1992 /* Add the new sequence of catches to the main one for this function. */
1993 push_to_full_sequence (catch_clauses, catch_clauses_last);
1994 emit_insns (new_catch_clause);
1995 end_full_sequence (&catch_clauses, &catch_clauses_last);
1997 /* Here we fall through into the continuation code. */
2000 /* Rethrow from the outer context LABEL. */
2003 expand_rethrow (label)
2006 if (exceptions_via_longjmp)
2009 if (flag_new_exceptions)
2013 if (label == NULL_RTX)
2014 label = last_rethrow_symbol;
2015 emit_library_call (rethrow_libfunc, 0, VOIDmode, 1, label, Pmode);
2016 region = find_func_region (eh_region_from_symbol (label));
2017 /* If the region is -1, it doesn't exist yet. We shouldn't be
2018 trying to rethrow there yet. */
2021 function_eh_regions[region].rethrow_ref = 1;
2023 /* Search backwards for the actual call insn. */
2024 insn = get_last_insn ();
2025 while (GET_CODE (insn) != CALL_INSN)
2026 insn = PREV_INSN (insn);
2027 delete_insns_since (insn);
2029 /* Mark the label/symbol on the call. */
2030 REG_NOTES (insn) = gen_rtx_EXPR_LIST (REG_EH_RETHROW, label,
2038 /* Begin a region that will contain entries created with
2039 add_partial_entry. */
2042 begin_protect_partials ()
2044 /* Put the entry on the function obstack. */
2045 push_obstacks_nochange ();
2046 resume_temporary_allocation ();
2048 /* Push room for a new list. */
2049 protect_list = tree_cons (NULL_TREE, NULL_TREE, protect_list);
2051 /* We're done with the function obstack now. */
2055 /* End all the pending exception regions on protect_list. The handlers
2056 will be emitted when expand_leftover_cleanups is invoked. */
2059 end_protect_partials ()
2063 /* For backwards compatibility, we allow callers to omit the call to
2064 begin_protect_partials for the outermost region. So,
2065 PROTECT_LIST may be NULL. */
2069 /* End all the exception regions. */
2070 for (t = TREE_VALUE (protect_list); t; t = TREE_CHAIN (t))
2071 expand_eh_region_end (TREE_VALUE (t));
2073 /* Pop the topmost entry. */
2074 protect_list = TREE_CHAIN (protect_list);
2078 /* Arrange for __terminate to be called if there is an unhandled throw
2082 protect_with_terminate (e)
2085 /* We only need to do this when using setjmp/longjmp EH and the
2086 language requires it, as otherwise we protect all of the handlers
2087 at once, if we need to. */
2088 if (exceptions_via_longjmp && protect_cleanup_actions_with_terminate)
2090 tree handler, result;
2092 /* All cleanups must be on the function_obstack. */
2093 push_obstacks_nochange ();
2094 resume_temporary_allocation ();
2096 handler = make_node (RTL_EXPR);
2097 TREE_TYPE (handler) = void_type_node;
2098 RTL_EXPR_RTL (handler) = const0_rtx;
2099 TREE_SIDE_EFFECTS (handler) = 1;
2100 start_sequence_for_rtl_expr (handler);
2102 emit_library_call (terminate_libfunc, 0, VOIDmode, 0);
2105 RTL_EXPR_SEQUENCE (handler) = get_insns ();
2108 result = build (TRY_CATCH_EXPR, TREE_TYPE (e), e, handler);
2109 TREE_SIDE_EFFECTS (result) = TREE_SIDE_EFFECTS (e);
2110 TREE_THIS_VOLATILE (result) = TREE_THIS_VOLATILE (e);
2111 TREE_READONLY (result) = TREE_READONLY (e);
2121 /* The exception table that we build that is used for looking up and
2122 dispatching exceptions, the current number of entries, and its
2123 maximum size before we have to extend it.
2125 The number in eh_table is the code label number of the exception
2126 handler for the region. This is added by add_eh_table_entry and
2127 used by output_exception_table_entry. */
2129 static int *eh_table = NULL;
2130 static int eh_table_size = 0;
2131 static int eh_table_max_size = 0;
2133 /* Note the need for an exception table entry for region N. If we
2134 don't need to output an explicit exception table, avoid all of the
2137 Called from final_scan_insn when a NOTE_INSN_EH_REGION_BEG is seen.
2138 (Or NOTE_INSN_EH_REGION_END sometimes)
2139 N is the NOTE_EH_HANDLER of the note, which comes from the code
2140 label number of the exception handler for the region. */
2143 add_eh_table_entry (n)
2146 #ifndef OMIT_EH_TABLE
2147 if (eh_table_size >= eh_table_max_size)
2151 eh_table_max_size += eh_table_max_size>>1;
2153 if (eh_table_max_size < 0)
2156 eh_table = (int *) xrealloc (eh_table,
2157 eh_table_max_size * sizeof (int));
2161 eh_table_max_size = 252;
2162 eh_table = (int *) xmalloc (eh_table_max_size * sizeof (int));
2165 eh_table[eh_table_size++] = n;
2167 if (flag_new_exceptions)
2169 /* We will output the exception table late in the compilation. That
2170 references type_info objects which should have already been output
2171 by that time. We explicitly mark those objects as being
2172 referenced now so we know to emit them. */
2173 struct handler_info *handler = get_first_handler (n);
2175 for (; handler; handler = handler->next)
2176 if (handler->type_info && handler->type_info != CATCH_ALL_TYPE)
2178 tree tinfo = (tree)handler->type_info;
2180 tinfo = TREE_OPERAND (tinfo, 0);
2181 TREE_SYMBOL_REFERENCED (DECL_ASSEMBLER_NAME (tinfo)) = 1;
2187 /* Return a non-zero value if we need to output an exception table.
2189 On some platforms, we don't have to output a table explicitly.
2190 This routine doesn't mean we don't have one. */
2193 exception_table_p ()
2201 /* Output the entry of the exception table corresponding to the
2202 exception region numbered N to file FILE.
2204 N is the code label number corresponding to the handler of the
2208 output_exception_table_entry (file, n)
2214 struct handler_info *handler = get_first_handler (n);
2215 int index = find_func_region (n);
2218 /* Form and emit the rethrow label, if needed */
2219 if (flag_new_exceptions
2220 && (handler || function_eh_regions[index].rethrow_ref))
2221 rethrow = function_eh_regions[index].rethrow_label;
2225 if (function_eh_regions[index].emitted)
2227 function_eh_regions[index].emitted = 1;
2229 for ( ; handler != NULL || rethrow != NULL_RTX; handler = handler->next)
2231 /* rethrow label should indicate the LAST entry for a region */
2232 if (rethrow != NULL_RTX && (handler == NULL || handler->next == NULL))
2234 ASM_GENERATE_INTERNAL_LABEL (buf, "LRTH", n);
2235 assemble_eh_label(buf);
2239 ASM_GENERATE_INTERNAL_LABEL (buf, "LEHB", n);
2240 sym = gen_rtx_SYMBOL_REF (Pmode, buf);
2241 assemble_eh_integer (sym, POINTER_SIZE / BITS_PER_UNIT, 1);
2243 ASM_GENERATE_INTERNAL_LABEL (buf, "LEHE", n);
2244 sym = gen_rtx_SYMBOL_REF (Pmode, buf);
2245 assemble_eh_integer (sym, POINTER_SIZE / BITS_PER_UNIT, 1);
2247 if (handler == NULL)
2248 assemble_eh_integer (GEN_INT (0), POINTER_SIZE / BITS_PER_UNIT, 1);
2251 ASM_GENERATE_INTERNAL_LABEL (buf, "L", handler->handler_number);
2252 sym = gen_rtx_SYMBOL_REF (Pmode, buf);
2253 assemble_eh_integer (sym, POINTER_SIZE / BITS_PER_UNIT, 1);
2256 if (flag_new_exceptions)
2258 if (handler == NULL || handler->type_info == NULL)
2259 assemble_eh_integer (const0_rtx, POINTER_SIZE / BITS_PER_UNIT, 1);
2261 if (handler->type_info == CATCH_ALL_TYPE)
2262 assemble_eh_integer (GEN_INT (CATCH_ALL_TYPE),
2263 POINTER_SIZE / BITS_PER_UNIT, 1);
2265 output_constant ((tree)(handler->type_info),
2266 POINTER_SIZE / BITS_PER_UNIT);
2268 putc ('\n', file); /* blank line */
2269 /* We only output the first label under the old scheme */
2270 if (! flag_new_exceptions || handler == NULL)
2275 /* Output the exception table if we have and need one. */
2277 static short language_code = 0;
2278 static short version_code = 0;
2280 /* This routine will set the language code for exceptions. */
2282 set_exception_lang_code (code)
2285 language_code = code;
2288 /* This routine will set the language version code for exceptions. */
2290 set_exception_version_code (code)
2293 version_code = code;
2296 /* Free the EH table structures. */
2298 free_exception_table ()
2301 clear_function_eh_region ();
2304 /* Output the common content of an exception table. */
2306 output_exception_table_data ()
2310 extern FILE *asm_out_file;
2312 if (flag_new_exceptions)
2314 assemble_eh_integer (GEN_INT (NEW_EH_RUNTIME),
2315 POINTER_SIZE / BITS_PER_UNIT, 1);
2316 assemble_eh_integer (GEN_INT (language_code), 2 , 1);
2317 assemble_eh_integer (GEN_INT (version_code), 2 , 1);
2319 /* Add enough padding to make sure table aligns on a pointer boundry. */
2320 i = GET_MODE_ALIGNMENT (ptr_mode) / BITS_PER_UNIT - 4;
2321 for ( ; i < 0; i = i + GET_MODE_ALIGNMENT (ptr_mode) / BITS_PER_UNIT)
2324 assemble_eh_integer (const0_rtx, i , 1);
2326 /* Generate the label for offset calculations on rethrows. */
2327 ASM_GENERATE_INTERNAL_LABEL (buf, "LRTH", 0);
2328 assemble_eh_label(buf);
2331 for (i = 0; i < eh_table_size; ++i)
2332 output_exception_table_entry (asm_out_file, eh_table[i]);
2336 /* Output an exception table for the entire compilation unit. */
2338 output_exception_table ()
2341 extern FILE *asm_out_file;
2343 if (! doing_eh (0) || ! eh_table)
2346 exception_section ();
2348 /* Beginning marker for table. */
2349 assemble_eh_align (GET_MODE_ALIGNMENT (ptr_mode));
2350 assemble_eh_label ("__EXCEPTION_TABLE__");
2352 output_exception_table_data ();
2354 /* Ending marker for table. */
2355 /* Generate the label for end of table. */
2356 ASM_GENERATE_INTERNAL_LABEL (buf, "LRTH", CODE_LABEL_NUMBER (final_rethrow));
2357 assemble_eh_label(buf);
2358 assemble_eh_integer (constm1_rtx, POINTER_SIZE / BITS_PER_UNIT, 1);
2360 /* For binary compatibility, the old __throw checked the second
2361 position for a -1, so we should output at least 2 -1's */
2362 if (! flag_new_exceptions)
2363 assemble_eh_integer (constm1_rtx, POINTER_SIZE / BITS_PER_UNIT, 1);
2365 putc ('\n', asm_out_file); /* blank line */
2368 /* Used by the ia64 unwind format to output data for an individual
2371 output_function_exception_table ()
2373 extern FILE *asm_out_file;
2375 if (! doing_eh (0) || ! eh_table)
2378 #ifdef HANDLER_SECTION
2382 output_exception_table_data ();
2384 /* Ending marker for table. */
2385 assemble_eh_integer (constm1_rtx, POINTER_SIZE / BITS_PER_UNIT, 1);
2387 putc ('\n', asm_out_file); /* blank line */
2391 /* Emit code to get EH context.
2393 We have to scan thru the code to find possible EH context registers.
2394 Inlined functions may use it too, and thus we'll have to be able
2397 This is done only if using exceptions_via_longjmp. */
2408 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
2409 if (GET_CODE (insn) == INSN
2410 && GET_CODE (PATTERN (insn)) == USE)
2412 rtx reg = find_reg_note (insn, REG_EH_CONTEXT, 0);
2419 /* If this is the first use insn, emit the call here. This
2420 will always be at the top of our function, because if
2421 expand_inline_function notices a REG_EH_CONTEXT note, it
2422 adds a use insn to this function as well. */
2424 ehc = call_get_eh_context ();
2426 emit_move_insn (XEXP (reg, 0), ehc);
2427 insns = get_insns ();
2430 emit_insns_before (insns, insn);
2435 /* Scan the insn chain F and build a list of handler labels. The
2436 resulting list is placed in the global variable exception_handler_labels. */
2439 find_exception_handler_labels_1 (f)
2444 /* For each start of a region, add its label to the list. */
2446 for (insn = f; insn; insn = NEXT_INSN (insn))
2448 struct handler_info* ptr;
2449 if (GET_CODE (insn) == NOTE
2450 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG)
2452 ptr = get_first_handler (NOTE_EH_HANDLER (insn));
2453 for ( ; ptr; ptr = ptr->next)
2455 /* make sure label isn't in the list already */
2457 for (x = exception_handler_labels; x; x = XEXP (x, 1))
2458 if (XEXP (x, 0) == ptr->handler_label)
2461 exception_handler_labels = gen_rtx_EXPR_LIST (VOIDmode,
2462 ptr->handler_label, exception_handler_labels);
2465 else if (GET_CODE (insn) == CALL_INSN
2466 && GET_CODE (PATTERN (insn)) == CALL_PLACEHOLDER)
2468 find_exception_handler_labels_1 (XEXP (PATTERN (insn), 0));
2469 find_exception_handler_labels_1 (XEXP (PATTERN (insn), 1));
2470 find_exception_handler_labels_1 (XEXP (PATTERN (insn), 2));
2475 /* Scan the current insns and build a list of handler labels. The
2476 resulting list is placed in the global variable exception_handler_labels.
2478 It is called after the last exception handling region is added to
2479 the current function (when the rtl is almost all built for the
2480 current function) and before the jump optimization pass. */
2482 find_exception_handler_labels ()
2484 exception_handler_labels = NULL_RTX;
2486 /* If we aren't doing exception handling, there isn't much to check. */
2490 find_exception_handler_labels_1 (get_insns ());
2493 /* Return a value of 1 if the parameter label number is an exception handler
2494 label. Return 0 otherwise. */
2497 is_exception_handler_label (lab)
2501 for (x = exception_handler_labels ; x ; x = XEXP (x, 1))
2502 if (lab == CODE_LABEL_NUMBER (XEXP (x, 0)))
2507 /* Perform sanity checking on the exception_handler_labels list.
2509 Can be called after find_exception_handler_labels is called to
2510 build the list of exception handlers for the current function and
2511 before we finish processing the current function. */
2514 check_exception_handler_labels ()
2518 /* If we aren't doing exception handling, there isn't much to check. */
2522 /* Make sure there is no more than 1 copy of a label */
2523 for (insn = exception_handler_labels; insn; insn = XEXP (insn, 1))
2526 for (insn2 = exception_handler_labels; insn2; insn2 = XEXP (insn2, 1))
2527 if (XEXP (insn, 0) == XEXP (insn2, 0))
2530 warning ("Counted %d copies of EH region %d in list.\n", count,
2531 CODE_LABEL_NUMBER (insn));
2536 /* Mark the children of NODE for GC. */
2540 struct eh_node *node;
2546 ggc_mark_rtx (node->entry->outer_context);
2547 ggc_mark_rtx (node->entry->exception_handler_label);
2548 ggc_mark_tree (node->entry->finalization);
2549 ggc_mark_rtx (node->entry->false_label);
2550 ggc_mark_rtx (node->entry->rethrow_label);
2552 node = node ->chain;
2556 /* Mark S for GC. */
2563 mark_eh_node (s->top);
2566 /* Mark Q for GC. */
2574 mark_eh_node (q->head);
2579 /* Mark NODE for GC. A label_node contains a union containing either
2580 a tree or an rtx. This label_node will contain a tree. */
2583 mark_tree_label_node (node)
2584 struct label_node *node;
2588 ggc_mark_tree (node->u.tlabel);
2593 /* Mark EH for GC. */
2597 struct eh_status *eh;
2602 mark_eh_stack (&eh->x_ehstack);
2603 mark_eh_stack (&eh->x_catchstack);
2604 mark_eh_queue (eh->x_ehqueue);
2605 ggc_mark_rtx (eh->x_catch_clauses);
2607 lang_mark_false_label_stack (eh->x_false_label_stack);
2608 mark_tree_label_node (eh->x_caught_return_label_stack);
2610 ggc_mark_tree (eh->x_protect_list);
2611 ggc_mark_rtx (eh->ehc);
2612 ggc_mark_rtx (eh->x_eh_return_stub_label);
2615 /* Mark ARG (which is really a struct func_eh_entry**) for GC. */
2618 mark_func_eh_entry (arg)
2621 struct func_eh_entry *fee;
2622 struct handler_info *h;
2625 fee = *((struct func_eh_entry **) arg);
2627 for (i = 0; i < current_func_eh_entry; ++i)
2629 ggc_mark_rtx (fee->rethrow_label);
2630 for (h = fee->handlers; h; h = h->next)
2632 ggc_mark_rtx (h->handler_label);
2633 if (h->type_info != CATCH_ALL_TYPE)
2634 ggc_mark_tree ((tree) h->type_info);
2637 /* Skip to the next entry in the array. */
2642 /* This group of functions initializes the exception handling data
2643 structures at the start of the compilation, initializes the data
2644 structures at the start of a function, and saves and restores the
2645 exception handling data structures for the start/end of a nested
2648 /* Toplevel initialization for EH things. */
2653 first_rethrow_symbol = create_rethrow_ref (0);
2654 final_rethrow = gen_exception_label ();
2655 last_rethrow_symbol = create_rethrow_ref (CODE_LABEL_NUMBER (final_rethrow));
2657 ggc_add_rtx_root (&exception_handler_labels, 1);
2658 ggc_add_rtx_root (&eh_return_context, 1);
2659 ggc_add_rtx_root (&eh_return_stack_adjust, 1);
2660 ggc_add_rtx_root (&eh_return_handler, 1);
2661 ggc_add_rtx_root (&first_rethrow_symbol, 1);
2662 ggc_add_rtx_root (&final_rethrow, 1);
2663 ggc_add_rtx_root (&last_rethrow_symbol, 1);
2664 ggc_add_root (&function_eh_regions, 1, sizeof (function_eh_regions),
2665 mark_func_eh_entry);
2668 /* Initialize the per-function EH information. */
2671 init_eh_for_function ()
2673 cfun->eh = (struct eh_status *) xcalloc (1, sizeof (struct eh_status));
2674 ehqueue = (struct eh_queue *) xcalloc (1, sizeof (struct eh_queue));
2675 eh_return_context = NULL_RTX;
2676 eh_return_stack_adjust = NULL_RTX;
2677 eh_return_handler = NULL_RTX;
2684 free (f->eh->x_ehqueue);
2689 /* This section is for the exception handling specific optimization
2692 /* Determine if the given INSN can throw an exception. */
2698 if (GET_CODE (insn) == INSN
2699 && GET_CODE (PATTERN (insn)) == SEQUENCE)
2700 insn = XVECEXP (PATTERN (insn), 0, 0);
2702 /* Calls can always potentially throw exceptions, unless they have
2703 a REG_EH_REGION note with a value of 0 or less. */
2704 if (GET_CODE (insn) == CALL_INSN)
2706 rtx note = find_reg_note (insn, REG_EH_REGION, NULL_RTX);
2707 if (!note || INTVAL (XEXP (note, 0)) > 0)
2711 if (asynchronous_exceptions)
2713 /* If we wanted asynchronous exceptions, then everything but NOTEs
2714 and CODE_LABELs could throw. */
2715 if (GET_CODE (insn) != NOTE && GET_CODE (insn) != CODE_LABEL)
2722 /* Return nonzero if nothing in this function can throw. */
2725 nothrow_function_p ()
2729 if (! flag_exceptions)
2732 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
2733 if (can_throw (insn))
2735 for (insn = current_function_epilogue_delay_list; insn;
2736 insn = XEXP (insn, 1))
2737 if (can_throw (insn))
2743 /* Scan a exception region looking for the matching end and then
2744 remove it if possible. INSN is the start of the region, N is the
2745 region number, and DELETE_OUTER is to note if anything in this
2748 Regions are removed if they cannot possibly catch an exception.
2749 This is determined by invoking can_throw on each insn within the
2750 region; if can_throw returns true for any of the instructions, the
2751 region can catch an exception, since there is an insn within the
2752 region that is capable of throwing an exception.
2754 Returns the NOTE_INSN_EH_REGION_END corresponding to this region, or
2755 calls abort if it can't find one.
2757 Can abort if INSN is not a NOTE_INSN_EH_REGION_BEGIN, or if N doesn't
2758 correspond to the region number, or if DELETE_OUTER is NULL. */
2761 scan_region (insn, n, delete_outer)
2768 /* Assume we can delete the region. */
2771 /* Can't delete something which is rethrown from. */
2772 if (rethrow_used (n))
2775 if (insn == NULL_RTX
2776 || GET_CODE (insn) != NOTE
2777 || NOTE_LINE_NUMBER (insn) != NOTE_INSN_EH_REGION_BEG
2778 || NOTE_EH_HANDLER (insn) != n
2779 || delete_outer == NULL)
2782 insn = NEXT_INSN (insn);
2784 /* Look for the matching end. */
2785 while (! (GET_CODE (insn) == NOTE
2786 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_END))
2788 /* If anything can throw, we can't remove the region. */
2789 if (delete && can_throw (insn))
2794 /* Watch out for and handle nested regions. */
2795 if (GET_CODE (insn) == NOTE
2796 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG)
2798 insn = scan_region (insn, NOTE_EH_HANDLER (insn), &delete);
2801 insn = NEXT_INSN (insn);
2804 /* The _BEG/_END NOTEs must match and nest. */
2805 if (NOTE_EH_HANDLER (insn) != n)
2808 /* If anything in this exception region can throw, we can throw. */
2813 /* Delete the start and end of the region. */
2814 delete_insn (start);
2817 /* We no longer removed labels here, since flow will now remove any
2818 handler which cannot be called any more. */
2821 /* Only do this part if we have built the exception handler
2823 if (exception_handler_labels)
2825 rtx x, *prev = &exception_handler_labels;
2827 /* Find it in the list of handlers. */
2828 for (x = exception_handler_labels; x; x = XEXP (x, 1))
2830 rtx label = XEXP (x, 0);
2831 if (CODE_LABEL_NUMBER (label) == n)
2833 /* If we are the last reference to the handler,
2835 if (--LABEL_NUSES (label) == 0)
2836 delete_insn (label);
2840 /* Remove it from the list of exception handler
2841 labels, if we are optimizing. If we are not, then
2842 leave it in the list, as we are not really going to
2843 remove the region. */
2844 *prev = XEXP (x, 1);
2851 prev = &XEXP (x, 1);
2859 /* Perform various interesting optimizations for exception handling
2862 We look for empty exception regions and make them go (away). The
2863 jump optimization code will remove the handler if nothing else uses
2867 exception_optimize ()
2872 /* Remove empty regions. */
2873 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
2875 if (GET_CODE (insn) == NOTE
2876 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG)
2878 /* Since scan_region will return the NOTE_INSN_EH_REGION_END
2879 insn, we will indirectly skip through all the insns
2880 inbetween. We are also guaranteed that the value of insn
2881 returned will be valid, as otherwise scan_region won't
2883 insn = scan_region (insn, NOTE_EH_HANDLER (insn), &n);
2888 /* This function determines whether the rethrow labels for any of the
2889 exception regions in the current function are used or not, and set
2890 the reference flag according. */
2893 update_rethrow_references ()
2897 int *saw_region, *saw_rethrow;
2899 if (!flag_new_exceptions)
2902 saw_region = (int *) xcalloc (current_func_eh_entry, sizeof (int));
2903 saw_rethrow = (int *) xcalloc (current_func_eh_entry, sizeof (int));
2905 /* Determine what regions exist, and whether there are any rethrows
2906 from those regions or not. */
2907 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
2908 if (GET_CODE (insn) == CALL_INSN)
2910 rtx note = find_reg_note (insn, REG_EH_RETHROW, NULL_RTX);
2913 region = eh_region_from_symbol (XEXP (note, 0));
2914 region = find_func_region (region);
2915 saw_rethrow[region] = 1;
2919 if (GET_CODE (insn) == NOTE)
2921 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG)
2923 region = find_func_region (NOTE_EH_HANDLER (insn));
2924 saw_region[region] = 1;
2928 /* For any regions we did see, set the referenced flag. */
2929 for (x = 0; x < current_func_eh_entry; x++)
2931 function_eh_regions[x].rethrow_ref = saw_rethrow[x];
2938 /* Various hooks for the DWARF 2 __throw routine. */
2940 /* Do any necessary initialization to access arbitrary stack frames.
2941 On the SPARC, this means flushing the register windows. */
2944 expand_builtin_unwind_init ()
2946 /* Set this so all the registers get saved in our frame; we need to be
2947 able to copy the saved values for any registers from frames we unwind. */
2948 current_function_has_nonlocal_label = 1;
2950 #ifdef SETUP_FRAME_ADDRESSES
2951 SETUP_FRAME_ADDRESSES ();
2955 /* Given a value extracted from the return address register or stack slot,
2956 return the actual address encoded in that value. */
2959 expand_builtin_extract_return_addr (addr_tree)
2962 rtx addr = expand_expr (addr_tree, NULL_RTX, Pmode, 0);
2963 return eh_outer_context (addr);
2966 /* Given an actual address in addr_tree, do any necessary encoding
2967 and return the value to be stored in the return address register or
2968 stack slot so the epilogue will return to that address. */
2971 expand_builtin_frob_return_addr (addr_tree)
2974 rtx addr = expand_expr (addr_tree, NULL_RTX, Pmode, 0);
2975 #ifdef RETURN_ADDR_OFFSET
2976 addr = plus_constant (addr, -RETURN_ADDR_OFFSET);
2981 /* Choose three registers for communication between the main body of
2982 __throw and the epilogue (or eh stub) and the exception handler.
2983 We must do this with hard registers because the epilogue itself
2984 will be generated after reload, at which point we may not reference
2987 The first passes the exception context to the handler. For this
2988 we use the return value register for a void*.
2990 The second holds the stack pointer value to be restored. For this
2991 we use the static chain register if it exists, is different from
2992 the previous, and is call-clobbered; otherwise some arbitrary
2993 call-clobbered register.
2995 The third holds the address of the handler itself. Here we use
2996 some arbitrary call-clobbered register. */
2999 eh_regs (pcontext, psp, pra, outgoing)
3000 rtx *pcontext, *psp, *pra;
3001 int outgoing ATTRIBUTE_UNUSED;
3003 rtx rcontext, rsp, rra;
3006 #ifdef FUNCTION_OUTGOING_VALUE
3008 rcontext = FUNCTION_OUTGOING_VALUE (build_pointer_type (void_type_node),
3009 current_function_decl);
3012 rcontext = FUNCTION_VALUE (build_pointer_type (void_type_node),
3013 current_function_decl);
3015 #ifdef STATIC_CHAIN_REGNUM
3017 rsp = static_chain_incoming_rtx;
3019 rsp = static_chain_rtx;
3020 if (REGNO (rsp) == REGNO (rcontext)
3021 || ! call_used_regs [REGNO (rsp)])
3022 #endif /* STATIC_CHAIN_REGNUM */
3025 if (rsp == NULL_RTX)
3027 for (i = 0; i < FIRST_PSEUDO_REGISTER; ++i)
3028 if (call_used_regs[i] && ! fixed_regs[i] && i != REGNO (rcontext))
3030 if (i == FIRST_PSEUDO_REGISTER)
3033 rsp = gen_rtx_REG (Pmode, i);
3036 for (i = 0; i < FIRST_PSEUDO_REGISTER; ++i)
3037 if (call_used_regs[i] && ! fixed_regs[i]
3038 && i != REGNO (rcontext) && i != REGNO (rsp))
3040 if (i == FIRST_PSEUDO_REGISTER)
3043 rra = gen_rtx_REG (Pmode, i);
3045 *pcontext = rcontext;
3050 /* Retrieve the register which contains the pointer to the eh_context
3051 structure set the __throw. */
3055 get_reg_for_handler ()
3058 reg1 = FUNCTION_VALUE (build_pointer_type (void_type_node),
3059 current_function_decl);
3064 /* Set up the epilogue with the magic bits we'll need to return to the
3065 exception handler. */
3068 expand_builtin_eh_return (context, stack, handler)
3069 tree context, stack, handler;
3071 if (eh_return_context)
3072 error("Duplicate call to __builtin_eh_return");
3075 = copy_to_reg (expand_expr (context, NULL_RTX, VOIDmode, 0));
3076 eh_return_stack_adjust
3077 = copy_to_reg (expand_expr (stack, NULL_RTX, VOIDmode, 0));
3079 = copy_to_reg (expand_expr (handler, NULL_RTX, VOIDmode, 0));
3085 rtx reg1, reg2, reg3;
3086 rtx stub_start, after_stub;
3089 if (!eh_return_context)
3092 current_function_cannot_inline = N_("function uses __builtin_eh_return");
3094 eh_regs (®1, ®2, ®3, 1);
3095 #ifdef POINTERS_EXTEND_UNSIGNED
3096 eh_return_context = convert_memory_address (Pmode, eh_return_context);
3097 eh_return_stack_adjust =
3098 convert_memory_address (Pmode, eh_return_stack_adjust);
3099 eh_return_handler = convert_memory_address (Pmode, eh_return_handler);
3101 emit_move_insn (reg1, eh_return_context);
3102 emit_move_insn (reg2, eh_return_stack_adjust);
3103 emit_move_insn (reg3, eh_return_handler);
3105 /* Talk directly to the target's epilogue code when possible. */
3107 #ifdef HAVE_eh_epilogue
3108 if (HAVE_eh_epilogue)
3110 emit_insn (gen_eh_epilogue (reg1, reg2, reg3));
3115 /* Otherwise, use the same stub technique we had before. */
3117 eh_return_stub_label = stub_start = gen_label_rtx ();
3118 after_stub = gen_label_rtx ();
3120 /* Set the return address to the stub label. */
3122 ra = expand_builtin_return_addr (BUILT_IN_RETURN_ADDRESS,
3123 0, hard_frame_pointer_rtx);
3124 if (GET_CODE (ra) == REG && REGNO (ra) >= FIRST_PSEUDO_REGISTER)
3127 tmp = memory_address (Pmode, gen_rtx_LABEL_REF (Pmode, stub_start));
3128 #ifdef RETURN_ADDR_OFFSET
3129 tmp = plus_constant (tmp, -RETURN_ADDR_OFFSET);
3131 tmp = force_operand (tmp, ra);
3133 emit_move_insn (ra, tmp);
3135 /* Indicate that the registers are in fact used. */
3136 emit_insn (gen_rtx_USE (VOIDmode, reg1));
3137 emit_insn (gen_rtx_USE (VOIDmode, reg2));
3138 emit_insn (gen_rtx_USE (VOIDmode, reg3));
3139 if (GET_CODE (ra) == REG)
3140 emit_insn (gen_rtx_USE (VOIDmode, ra));
3142 /* Generate the stub. */
3144 emit_jump (after_stub);
3145 emit_label (stub_start);
3147 eh_regs (®1, ®2, ®3, 0);
3148 adjust_stack (reg2);
3149 emit_indirect_jump (reg3);
3151 emit_label (after_stub);
3155 /* This contains the code required to verify whether arbitrary instructions
3156 are in the same exception region. */
3158 static int *insn_eh_region = (int *)0;
3159 static int maximum_uid;
3162 set_insn_eh_region (first, region_num)
3169 for (insn = *first; insn; insn = NEXT_INSN (insn))
3171 if ((GET_CODE (insn) == NOTE)
3172 && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG))
3174 rnum = NOTE_EH_HANDLER (insn);
3175 insn_eh_region[INSN_UID (insn)] = rnum;
3176 insn = NEXT_INSN (insn);
3177 set_insn_eh_region (&insn, rnum);
3178 /* Upon return, insn points to the EH_REGION_END of nested region */
3181 insn_eh_region[INSN_UID (insn)] = region_num;
3182 if ((GET_CODE (insn) == NOTE) &&
3183 (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_END))
3189 /* Free the insn table, an make sure it cannot be used again. */
3192 free_insn_eh_region ()
3199 free (insn_eh_region);
3200 insn_eh_region = (int *)0;
3204 /* Initialize the table. max_uid must be calculated and handed into
3205 this routine. If it is unavailable, passing a value of 0 will
3206 cause this routine to calculate it as well. */
3209 init_insn_eh_region (first, max_uid)
3219 free_insn_eh_region();
3222 for (insn = first; insn; insn = NEXT_INSN (insn))
3223 if (INSN_UID (insn) > max_uid) /* find largest UID */
3224 max_uid = INSN_UID (insn);
3226 maximum_uid = max_uid;
3227 insn_eh_region = (int *) xmalloc ((max_uid + 1) * sizeof (int));
3229 set_insn_eh_region (&insn, 0);
3233 /* Check whether 2 instructions are within the same region. */
3236 in_same_eh_region (insn1, insn2)
3239 int ret, uid1, uid2;
3241 /* If no exceptions, instructions are always in same region. */
3245 /* If the table isn't allocated, assume the worst. */
3246 if (!insn_eh_region)
3249 uid1 = INSN_UID (insn1);
3250 uid2 = INSN_UID (insn2);
3252 /* if instructions have been allocated beyond the end, either
3253 the table is out of date, or this is a late addition, or
3254 something... Assume the worst. */
3255 if (uid1 > maximum_uid || uid2 > maximum_uid)
3258 ret = (insn_eh_region[uid1] == insn_eh_region[uid2]);
3263 /* This function will initialize the handler list for a specified block.
3264 It may recursively call itself if the outer block hasn't been processed
3265 yet. At some point in the future we can trim out handlers which we
3266 know cannot be called. (ie, if a block has an INT type handler,
3267 control will never be passed to an outer INT type handler). */
3270 process_nestinfo (block, info, nested_eh_region)
3272 eh_nesting_info *info;
3273 int *nested_eh_region;
3275 handler_info *ptr, *last_ptr = NULL;
3276 int x, y, count = 0;
3278 handler_info **extra_handlers = 0;
3279 int index = info->region_index[block];
3281 /* If we've already processed this block, simply return. */
3282 if (info->num_handlers[index] > 0)
3285 for (ptr = get_first_handler (block); ptr; last_ptr = ptr, ptr = ptr->next)
3288 /* pick up any information from the next outer region. It will already
3289 contain a summary of itself and all outer regions to it. */
3291 if (nested_eh_region [block] != 0)
3293 int nested_index = info->region_index[nested_eh_region[block]];
3294 process_nestinfo (nested_eh_region[block], info, nested_eh_region);
3295 extra = info->num_handlers[nested_index];
3296 extra_handlers = info->handlers[nested_index];
3297 info->outer_index[index] = nested_index;
3300 /* If the last handler is either a CATCH_ALL or a cleanup, then we
3301 won't use the outer ones since we know control will not go past the
3302 catch-all or cleanup. */
3304 if (last_ptr != NULL && (last_ptr->type_info == NULL
3305 || last_ptr->type_info == CATCH_ALL_TYPE))
3308 info->num_handlers[index] = count + extra;
3309 info->handlers[index] = (handler_info **) xmalloc ((count + extra)
3310 * sizeof (handler_info **));
3312 /* First put all our handlers into the list. */
3313 ptr = get_first_handler (block);
3314 for (x = 0; x < count; x++)
3316 info->handlers[index][x] = ptr;
3320 /* Now add all the outer region handlers, if they aren't they same as
3321 one of the types in the current block. We won't worry about
3322 derived types yet, we'll just look for the exact type. */
3323 for (y =0, x = 0; x < extra ; x++)
3327 /* Check to see if we have a type duplication. */
3328 for (i = 0; i < count; i++)
3329 if (info->handlers[index][i]->type_info == extra_handlers[x]->type_info)
3332 /* Record one less handler. */
3333 (info->num_handlers[index])--;
3338 info->handlers[index][y + count] = extra_handlers[x];
3344 /* This function will allocate and initialize an eh_nesting_info structure.
3345 It returns a pointer to the completed data structure. If there are
3346 no exception regions, a NULL value is returned. */
3349 init_eh_nesting_info ()
3351 int *nested_eh_region;
3352 int region_count = 0;
3353 rtx eh_note = NULL_RTX;
3354 eh_nesting_info *info;
3358 if (! flag_exceptions)
3361 info = (eh_nesting_info *) xmalloc (sizeof (eh_nesting_info));
3362 info->region_index = (int *) xcalloc ((max_label_num () + 1), sizeof (int));
3363 nested_eh_region = (int *) xcalloc (max_label_num () + 1, sizeof (int));
3365 /* Create the nested_eh_region list. If indexed with a block number, it
3366 returns the block number of the next outermost region, if any.
3367 We can count the number of regions and initialize the region_index
3368 vector at the same time. */
3369 for (insn = get_insns(); insn; insn = NEXT_INSN (insn))
3371 if (GET_CODE (insn) == NOTE)
3373 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG)
3375 int block = NOTE_EH_HANDLER (insn);
3377 info->region_index[block] = region_count;
3379 nested_eh_region [block] =
3380 NOTE_EH_HANDLER (XEXP (eh_note, 0));
3382 nested_eh_region [block] = 0;
3383 eh_note = gen_rtx_EXPR_LIST (VOIDmode, insn, eh_note);
3385 else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_END)
3386 eh_note = XEXP (eh_note, 1);
3390 /* If there are no regions, wrap it up now. */
3391 if (region_count == 0)
3393 free (info->region_index);
3395 free (nested_eh_region);
3400 info->handlers = (handler_info ***) xcalloc (region_count,
3401 sizeof (handler_info ***));
3402 info->num_handlers = (int *) xcalloc (region_count, sizeof (int));
3403 info->outer_index = (int *) xcalloc (region_count, sizeof (int));
3405 /* Now initialize the handler lists for all exception blocks. */
3406 for (x = 0; x <= max_label_num (); x++)
3408 if (info->region_index[x] != 0)
3409 process_nestinfo (x, info, nested_eh_region);
3411 info->region_count = region_count;
3414 free (nested_eh_region);
3420 /* This function is used to retreive the vector of handlers which
3421 can be reached by a given insn in a given exception region.
3422 BLOCK is the exception block the insn is in.
3423 INFO is the eh_nesting_info structure.
3424 INSN is the (optional) insn within the block. If insn is not NULL_RTX,
3425 it may contain reg notes which modify its throwing behavior, and
3426 these will be obeyed. If NULL_RTX is passed, then we simply return the
3428 HANDLERS is the address of a pointer to a vector of handler_info pointers.
3429 Upon return, this will have the handlers which can be reached by block.
3430 This function returns the number of elements in the handlers vector. */
3433 reachable_handlers (block, info, insn, handlers)
3435 eh_nesting_info *info;
3437 handler_info ***handlers;
3445 index = info->region_index[block];
3447 if (insn && GET_CODE (insn) == CALL_INSN)
3449 /* RETHROWs specify a region number from which we are going to rethrow.
3450 This means we won't pass control to handlers in the specified
3451 region, but rather any region OUTSIDE the specified region.
3452 We accomplish this by setting block to the outer_index of the
3453 specified region. */
3454 rtx note = find_reg_note (insn, REG_EH_RETHROW, NULL_RTX);
3457 index = eh_region_from_symbol (XEXP (note, 0));
3458 index = info->region_index[index];
3460 index = info->outer_index[index];
3464 /* If there is no rethrow, we look for a REG_EH_REGION, and
3465 we'll throw from that block. A value of 0 or less
3466 indicates that this insn cannot throw. */
3467 note = find_reg_note (insn, REG_EH_REGION, NULL_RTX);
3470 int b = INTVAL (XEXP (note, 0));
3474 index = info->region_index[b];
3478 /* If we reach this point, and index is 0, there is no throw. */
3482 *handlers = info->handlers[index];
3483 return info->num_handlers[index];
3487 /* This function will free all memory associated with the eh_nesting info. */
3490 free_eh_nesting_info (info)
3491 eh_nesting_info *info;
3496 if (info->region_index)
3497 free (info->region_index);
3498 if (info->num_handlers)
3499 free (info->num_handlers);
3500 if (info->outer_index)
3501 free (info->outer_index);
3504 for (x = 0; x < info->region_count; x++)
3505 if (info->handlers[x])
3506 free (info->handlers[x]);
3507 free (info->handlers);