1 /* Implements exception handling.
2 Copyright (C) 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
3 1999, 2000, 2001 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 "eh-common.h"
399 #include "function.h"
402 #include "hard-reg-set.h"
403 #include "insn-config.h"
412 /* One to use setjmp/longjmp method of generating code for exception
415 int exceptions_via_longjmp = 2;
417 /* One to enable asynchronous exception support. */
419 int asynchronous_exceptions = 0;
421 /* One to protect cleanup actions with a handler that calls
422 __terminate, zero otherwise. */
424 int protect_cleanup_actions_with_terminate;
426 /* A list of labels used for exception handlers. Created by
427 find_exception_handler_labels for the optimization passes. */
429 rtx exception_handler_labels;
431 /* Keeps track of the label used as the context of a throw to rethrow an
432 exception to the outer exception region. */
434 struct label_node *outer_context_label_stack = NULL;
436 /* Pseudos used to hold exception return data in the interim between
437 __builtin_eh_return and the end of the function. */
439 static rtx eh_return_context;
440 static rtx eh_return_stack_adjust;
441 static rtx eh_return_handler;
443 /* This is used for targets which can call rethrow with an offset instead
444 of an address. This is subtracted from the rethrow label we are
447 static rtx first_rethrow_symbol = NULL_RTX;
448 static rtx final_rethrow = NULL_RTX;
449 static rtx last_rethrow_symbol = NULL_RTX;
452 /* Prototypes for local functions. */
454 static void push_eh_entry PARAMS ((struct eh_stack *));
455 static struct eh_entry * pop_eh_entry PARAMS ((struct eh_stack *));
456 static void enqueue_eh_entry PARAMS ((struct eh_queue *, struct eh_entry *));
457 static struct eh_entry * dequeue_eh_entry PARAMS ((struct eh_queue *));
458 static rtx call_get_eh_context PARAMS ((void));
459 static void start_dynamic_cleanup PARAMS ((tree, tree));
460 static void start_dynamic_handler PARAMS ((void));
461 static void expand_rethrow PARAMS ((rtx));
462 static void output_exception_table_entry PARAMS ((FILE *, int));
463 static rtx scan_region PARAMS ((rtx, int, int *));
464 static void eh_regs PARAMS ((rtx *, rtx *, rtx *, int));
465 static void set_insn_eh_region PARAMS ((rtx *, int));
466 #ifdef DONT_USE_BUILTIN_SETJMP
467 static void jumpif_rtx PARAMS ((rtx, rtx));
469 static void find_exception_handler_labels_1 PARAMS ((rtx));
470 static void mark_eh_node PARAMS ((struct eh_node *));
471 static void mark_eh_stack PARAMS ((struct eh_stack *));
472 static void mark_eh_queue PARAMS ((struct eh_queue *));
473 static void mark_tree_label_node PARAMS ((struct label_node *));
474 static void mark_func_eh_entry PARAMS ((void *));
475 static rtx create_rethrow_ref PARAMS ((int));
476 static void push_entry PARAMS ((struct eh_stack *, struct eh_entry*));
477 static void receive_exception_label PARAMS ((rtx));
478 static int new_eh_region_entry PARAMS ((int, rtx));
479 static int find_func_region PARAMS ((int));
480 static int find_func_region_from_symbol PARAMS ((rtx));
481 static void clear_function_eh_region PARAMS ((void));
482 static void process_nestinfo PARAMS ((int, eh_nesting_info *, int *));
483 rtx expand_builtin_return_addr PARAMS ((enum built_in_function, int, rtx));
484 static void emit_cleanup_handler PARAMS ((struct eh_entry *));
485 static int eh_region_from_symbol PARAMS ((rtx));
488 /* Various support routines to manipulate the various data structures
489 used by the exception handling code. */
491 extern struct obstack permanent_obstack;
493 /* Generate a SYMBOL_REF for rethrow to use */
496 create_rethrow_ref (region_num)
503 ASM_GENERATE_INTERNAL_LABEL (buf, "LRTH", region_num);
504 ptr = ggc_strdup (buf);
505 def = gen_rtx_SYMBOL_REF (Pmode, ptr);
506 SYMBOL_REF_NEED_ADJUST (def) = 1;
511 /* Push a label entry onto the given STACK. */
514 push_label_entry (stack, rlabel, tlabel)
515 struct label_node **stack;
519 struct label_node *newnode
520 = (struct label_node *) xmalloc (sizeof (struct label_node));
523 newnode->u.rlabel = rlabel;
525 newnode->u.tlabel = tlabel;
526 newnode->chain = *stack;
530 /* Pop a label entry from the given STACK. */
533 pop_label_entry (stack)
534 struct label_node **stack;
537 struct label_node *tempnode;
543 label = tempnode->u.rlabel;
544 *stack = (*stack)->chain;
550 /* Return the top element of the given STACK. */
553 top_label_entry (stack)
554 struct label_node **stack;
559 return (*stack)->u.tlabel;
562 /* Get an exception label. */
565 gen_exception_label ()
568 lab = gen_label_rtx ();
572 /* Push a new eh_node entry onto STACK. */
575 push_eh_entry (stack)
576 struct eh_stack *stack;
578 struct eh_node *node = (struct eh_node *) xmalloc (sizeof (struct eh_node));
579 struct eh_entry *entry = (struct eh_entry *) xmalloc (sizeof (struct eh_entry));
581 rtx rlab = gen_exception_label ();
582 entry->finalization = NULL_TREE;
583 entry->label_used = 0;
584 entry->exception_handler_label = rlab;
585 entry->false_label = NULL_RTX;
586 if (! flag_new_exceptions)
587 entry->outer_context = gen_label_rtx ();
589 entry->outer_context = create_rethrow_ref (CODE_LABEL_NUMBER (rlab));
590 entry->rethrow_label = entry->outer_context;
591 entry->goto_entry_p = 0;
594 node->chain = stack->top;
598 /* Push an existing entry onto a stack. */
601 push_entry (stack, entry)
602 struct eh_stack *stack;
603 struct eh_entry *entry;
605 struct eh_node *node = (struct eh_node *) xmalloc (sizeof (struct eh_node));
607 node->chain = stack->top;
611 /* Pop an entry from the given STACK. */
613 static struct eh_entry *
615 struct eh_stack *stack;
617 struct eh_node *tempnode;
618 struct eh_entry *tempentry;
620 tempnode = stack->top;
621 tempentry = tempnode->entry;
622 stack->top = stack->top->chain;
628 /* Enqueue an ENTRY onto the given QUEUE. */
631 enqueue_eh_entry (queue, entry)
632 struct eh_queue *queue;
633 struct eh_entry *entry;
635 struct eh_node *node = (struct eh_node *) xmalloc (sizeof (struct eh_node));
640 if (queue->head == NULL)
643 queue->tail->chain = node;
647 /* Dequeue an entry from the given QUEUE. */
649 static struct eh_entry *
650 dequeue_eh_entry (queue)
651 struct eh_queue *queue;
653 struct eh_node *tempnode;
654 struct eh_entry *tempentry;
656 if (queue->head == NULL)
659 tempnode = queue->head;
660 queue->head = queue->head->chain;
662 tempentry = tempnode->entry;
669 receive_exception_label (handler_label)
672 rtx around_label = NULL_RTX;
674 if (! flag_new_exceptions || exceptions_via_longjmp)
676 around_label = gen_label_rtx ();
677 emit_jump (around_label);
681 emit_label (handler_label);
683 if (! exceptions_via_longjmp)
685 #ifdef HAVE_exception_receiver
686 if (HAVE_exception_receiver)
687 emit_insn (gen_exception_receiver ());
690 #ifdef HAVE_nonlocal_goto_receiver
691 if (HAVE_nonlocal_goto_receiver)
692 emit_insn (gen_nonlocal_goto_receiver ());
699 #ifndef DONT_USE_BUILTIN_SETJMP
700 expand_builtin_setjmp_receiver (handler_label);
705 emit_label (around_label);
711 int range_number; /* EH region number from EH NOTE insn's. */
712 rtx rethrow_label; /* Label for rethrow. */
713 int rethrow_ref; /* Is rethrow_label referenced? */
714 int emitted; /* 1 if this entry has been emitted in assembly file. */
715 struct handler_info *handlers;
719 /* table of function eh regions */
720 static struct func_eh_entry *function_eh_regions = NULL;
721 static int num_func_eh_entries = 0;
722 static int current_func_eh_entry = 0;
724 #define SIZE_FUNC_EH(X) (sizeof (struct func_eh_entry) * X)
726 /* Add a new eh_entry for this function. The number returned is an
727 number which uniquely identifies this exception range. */
730 new_eh_region_entry (note_eh_region, rethrow)
734 if (current_func_eh_entry == num_func_eh_entries)
736 if (num_func_eh_entries == 0)
738 function_eh_regions =
739 (struct func_eh_entry *) xmalloc (SIZE_FUNC_EH (50));
740 num_func_eh_entries = 50;
744 num_func_eh_entries = num_func_eh_entries * 3 / 2;
745 function_eh_regions = (struct func_eh_entry *)
746 xrealloc (function_eh_regions, SIZE_FUNC_EH (num_func_eh_entries));
749 function_eh_regions[current_func_eh_entry].range_number = note_eh_region;
750 if (rethrow == NULL_RTX)
751 function_eh_regions[current_func_eh_entry].rethrow_label =
752 create_rethrow_ref (note_eh_region);
754 function_eh_regions[current_func_eh_entry].rethrow_label = rethrow;
755 function_eh_regions[current_func_eh_entry].handlers = NULL;
756 function_eh_regions[current_func_eh_entry].emitted = 0;
758 return current_func_eh_entry++;
761 /* Add new handler information to an exception range. The first parameter
762 specifies the range number (returned from new_eh_entry()). The second
763 parameter specifies the handler. By default the handler is inserted at
764 the end of the list. A handler list may contain only ONE NULL_TREE
765 typeinfo entry. Regardless where it is positioned, a NULL_TREE entry
766 is always output as the LAST handler in the exception table for a region. */
769 add_new_handler (region, newhandler)
771 struct handler_info *newhandler;
773 struct handler_info *last;
775 /* If find_func_region returns -1, callers might attempt to pass us
776 this region number. If that happens, something has gone wrong;
777 -1 is never a valid region. */
781 newhandler->next = NULL;
782 last = function_eh_regions[region].handlers;
784 function_eh_regions[region].handlers = newhandler;
787 for ( ; ; last = last->next)
789 if (last->type_info == CATCH_ALL_TYPE)
790 pedwarn ("additional handler after ...");
791 if (last->next == NULL)
794 last->next = newhandler;
798 /* Remove a handler label. The handler label is being deleted, so all
799 regions which reference this handler should have it removed from their
800 list of possible handlers. Any region which has the final handler
801 removed can be deleted. */
803 void remove_handler (removing_label)
806 struct handler_info *handler, *last;
808 for (x = 0 ; x < current_func_eh_entry; ++x)
811 handler = function_eh_regions[x].handlers;
812 for ( ; handler; last = handler, handler = handler->next)
813 if (handler->handler_label == removing_label)
817 last->next = handler->next;
821 function_eh_regions[x].handlers = handler->next;
826 /* This function will return a malloc'd pointer to an array of
827 void pointer representing the runtime match values that
828 currently exist in all regions. */
831 find_all_handler_type_matches (array)
834 struct handler_info *handler, *last;
843 if (!doing_eh (0) || ! flag_new_exceptions)
847 ptr = (void **) xmalloc (max_ptr * sizeof (void *));
849 for (x = 0 ; x < current_func_eh_entry; x++)
852 handler = function_eh_regions[x].handlers;
853 for ( ; handler; last = handler, handler = handler->next)
855 val = handler->type_info;
856 if (val != NULL && val != CATCH_ALL_TYPE)
858 /* See if this match value has already been found. */
859 for (y = 0; y < n_ptr; y++)
863 /* If we break early, we already found this value. */
867 /* Do we need to allocate more space? */
868 if (n_ptr >= max_ptr)
870 max_ptr += max_ptr / 2;
871 ptr = (void **) xrealloc (ptr, max_ptr * sizeof (void *));
888 /* Create a new handler structure initialized with the handler label and
889 typeinfo fields passed in. */
891 struct handler_info *
892 get_new_handler (handler, typeinfo)
896 struct handler_info* ptr;
897 ptr = (struct handler_info *) xmalloc (sizeof (struct handler_info));
898 ptr->handler_label = handler;
899 ptr->handler_number = CODE_LABEL_NUMBER (handler);
900 ptr->type_info = typeinfo;
908 /* Find the index in function_eh_regions associated with a NOTE region. If
909 the region cannot be found, a -1 is returned. */
912 find_func_region (insn_region)
916 for (x = 0; x < current_func_eh_entry; x++)
917 if (function_eh_regions[x].range_number == insn_region)
923 /* Get a pointer to the first handler in an exception region's list. */
925 struct handler_info *
926 get_first_handler (region)
929 int r = find_func_region (region);
932 return function_eh_regions[r].handlers;
935 /* Clean out the function_eh_region table and free all memory */
938 clear_function_eh_region ()
941 struct handler_info *ptr, *next;
942 for (x = 0; x < current_func_eh_entry; x++)
943 for (ptr = function_eh_regions[x].handlers; ptr != NULL; ptr = next)
948 if (function_eh_regions)
949 free (function_eh_regions);
950 num_func_eh_entries = 0;
951 current_func_eh_entry = 0;
954 /* Make a duplicate of an exception region by copying all the handlers
955 for an exception region. Return the new handler index. The final
956 parameter is a routine which maps old labels to new ones. */
959 duplicate_eh_handlers (old_note_eh_region, new_note_eh_region, map)
960 int old_note_eh_region, new_note_eh_region;
961 rtx (*map) PARAMS ((rtx));
963 struct handler_info *ptr, *new_ptr;
964 int new_region, region;
966 region = find_func_region (old_note_eh_region);
968 /* Cannot duplicate non-existant exception region. */
971 /* duplicate_eh_handlers may have been called during a symbol remap. */
972 new_region = find_func_region (new_note_eh_region);
973 if (new_region != -1)
976 new_region = new_eh_region_entry (new_note_eh_region, NULL_RTX);
978 ptr = function_eh_regions[region].handlers;
980 for ( ; ptr; ptr = ptr->next)
982 new_ptr = get_new_handler (map (ptr->handler_label), ptr->type_info);
983 add_new_handler (new_region, new_ptr);
990 /* Given a rethrow symbol, find the EH region number this is for. */
993 eh_region_from_symbol (sym)
997 if (sym == last_rethrow_symbol)
999 for (x = 0; x < current_func_eh_entry; x++)
1000 if (function_eh_regions[x].rethrow_label == sym)
1001 return function_eh_regions[x].range_number;
1005 /* Like find_func_region, but using the rethrow symbol for the region
1006 rather than the region number itself. */
1009 find_func_region_from_symbol (sym)
1012 return find_func_region (eh_region_from_symbol (sym));
1015 /* When inlining/unrolling, we have to map the symbols passed to
1016 __rethrow as well. This performs the remap. If a symbol isn't foiund,
1017 the original one is returned. This is not an efficient routine,
1018 so don't call it on everything!! */
1021 rethrow_symbol_map (sym, map)
1023 rtx (*map) PARAMS ((rtx));
1027 if (! flag_new_exceptions)
1030 for (x = 0; x < current_func_eh_entry; x++)
1031 if (function_eh_regions[x].rethrow_label == sym)
1033 /* We've found the original region, now lets determine which region
1034 this now maps to. */
1035 rtx l1 = function_eh_regions[x].handlers->handler_label;
1037 y = CODE_LABEL_NUMBER (l2); /* This is the new region number */
1038 x = find_func_region (y); /* Get the new permanent region */
1039 if (x == -1) /* Hmm, Doesn't exist yet */
1041 x = duplicate_eh_handlers (CODE_LABEL_NUMBER (l1), y, map);
1042 /* Since we're mapping it, it must be used. */
1043 function_eh_regions[x].rethrow_ref = 1;
1045 return function_eh_regions[x].rethrow_label;
1050 /* Returns nonzero if the rethrow label for REGION is referenced
1051 somewhere (i.e. we rethrow out of REGION or some other region
1052 masquerading as REGION). */
1055 rethrow_used (region)
1058 if (flag_new_exceptions)
1060 int ret = function_eh_regions[find_func_region (region)].rethrow_ref;
1067 /* Routine to see if exception handling is turned on.
1068 DO_WARN is non-zero if we want to inform the user that exception
1069 handling is turned off.
1071 This is used to ensure that -fexceptions has been specified if the
1072 compiler tries to use any exception-specific functions. */
1078 if (! flag_exceptions)
1080 static int warned = 0;
1081 if (! warned && do_warn)
1083 error ("exception handling disabled, use -fexceptions to enable");
1091 /* Given a return address in ADDR, determine the address we should use
1092 to find the corresponding EH region. */
1095 eh_outer_context (addr)
1098 /* First mask out any unwanted bits. */
1099 #ifdef MASK_RETURN_ADDR
1100 expand_and (addr, MASK_RETURN_ADDR, addr);
1103 /* Then adjust to find the real return address. */
1104 #if defined (RETURN_ADDR_OFFSET)
1105 addr = plus_constant (addr, RETURN_ADDR_OFFSET);
1111 /* Start a new exception region for a region of code that has a
1112 cleanup action and push the HANDLER for the region onto
1113 protect_list. All of the regions created with add_partial_entry
1114 will be ended when end_protect_partials is invoked. */
1117 add_partial_entry (handler)
1120 expand_eh_region_start ();
1122 /* Because this is a cleanup action, we may have to protect the handler
1123 with __terminate. */
1124 handler = protect_with_terminate (handler);
1126 /* For backwards compatibility, we allow callers to omit calls to
1127 begin_protect_partials for the outermost region. So, we must
1128 explicitly do so here. */
1130 begin_protect_partials ();
1132 /* Add this entry to the front of the list. */
1133 TREE_VALUE (protect_list)
1134 = tree_cons (NULL_TREE, handler, TREE_VALUE (protect_list));
1137 /* Emit code to get EH context to current function. */
1140 call_get_eh_context ()
1145 if (fn == NULL_TREE)
1148 fn = get_identifier ("__get_eh_context");
1149 fntype = build_pointer_type (build_pointer_type
1150 (build_pointer_type (void_type_node)));
1151 fntype = build_function_type (fntype, NULL_TREE);
1152 fn = build_decl (FUNCTION_DECL, fn, fntype);
1153 DECL_EXTERNAL (fn) = 1;
1154 TREE_PUBLIC (fn) = 1;
1155 DECL_ARTIFICIAL (fn) = 1;
1156 TREE_READONLY (fn) = 1;
1157 make_decl_rtl (fn, NULL_PTR);
1158 assemble_external (fn);
1160 ggc_add_tree_root (&fn, 1);
1163 expr = build1 (ADDR_EXPR, build_pointer_type (TREE_TYPE (fn)), fn);
1164 expr = build (CALL_EXPR, TREE_TYPE (TREE_TYPE (fn)),
1165 expr, NULL_TREE, NULL_TREE);
1166 TREE_SIDE_EFFECTS (expr) = 1;
1168 return copy_to_reg (expand_expr (expr, NULL_RTX, VOIDmode, 0));
1171 /* Get a reference to the EH context.
1172 We will only generate a register for the current function EH context here,
1173 and emit a USE insn to mark that this is a EH context register.
1175 Later, emit_eh_context will emit needed call to __get_eh_context
1176 in libgcc2, and copy the value to the register we have generated. */
1181 if (current_function_ehc == 0)
1185 current_function_ehc = gen_reg_rtx (Pmode);
1187 insn = gen_rtx_USE (GET_MODE (current_function_ehc),
1188 current_function_ehc);
1189 insn = emit_insn_before (insn, get_first_nonparm_insn ());
1192 = gen_rtx_EXPR_LIST (REG_EH_CONTEXT, current_function_ehc,
1195 return current_function_ehc;
1198 /* Get a reference to the dynamic handler chain. It points to the
1199 pointer to the next element in the dynamic handler chain. It ends
1200 when there are no more elements in the dynamic handler chain, when
1201 the value is &top_elt from libgcc2.c. Immediately after the
1202 pointer, is an area suitable for setjmp/longjmp when
1203 DONT_USE_BUILTIN_SETJMP is defined, and an area suitable for
1204 __builtin_setjmp/__builtin_longjmp when DONT_USE_BUILTIN_SETJMP
1208 get_dynamic_handler_chain ()
1210 rtx ehc, dhc, result;
1212 ehc = get_eh_context ();
1214 /* This is the offset of dynamic_handler_chain in the eh_context struct
1215 declared in eh-common.h. If its location is change, change this offset */
1216 dhc = plus_constant (ehc, POINTER_SIZE / BITS_PER_UNIT);
1218 result = copy_to_reg (dhc);
1220 /* We don't want a copy of the dcc, but rather, the single dcc. */
1221 return gen_rtx_MEM (Pmode, result);
1224 /* Get a reference to the dynamic cleanup chain. It points to the
1225 pointer to the next element in the dynamic cleanup chain.
1226 Immediately after the pointer, are two Pmode variables, one for a
1227 pointer to a function that performs the cleanup action, and the
1228 second, the argument to pass to that function. */
1231 get_dynamic_cleanup_chain ()
1233 rtx dhc, dcc, result;
1235 dhc = get_dynamic_handler_chain ();
1236 dcc = plus_constant (dhc, POINTER_SIZE / BITS_PER_UNIT);
1238 result = copy_to_reg (dcc);
1240 /* We don't want a copy of the dcc, but rather, the single dcc. */
1241 return gen_rtx_MEM (Pmode, result);
1244 #ifdef DONT_USE_BUILTIN_SETJMP
1245 /* Generate code to evaluate X and jump to LABEL if the value is nonzero.
1246 LABEL is an rtx of code CODE_LABEL, in this function. */
1249 jumpif_rtx (x, label)
1253 jumpif (make_tree (type_for_mode (GET_MODE (x), 0), x), label);
1257 /* Start a dynamic cleanup on the EH runtime dynamic cleanup stack.
1258 We just need to create an element for the cleanup list, and push it
1261 A dynamic cleanup is a cleanup action implied by the presence of an
1262 element on the EH runtime dynamic cleanup stack that is to be
1263 performed when an exception is thrown. The cleanup action is
1264 performed by __sjthrow when an exception is thrown. Only certain
1265 actions can be optimized into dynamic cleanup actions. For the
1266 restrictions on what actions can be performed using this routine,
1267 see expand_eh_region_start_tree. */
1270 start_dynamic_cleanup (func, arg)
1275 rtx new_func, new_arg;
1279 /* We allocate enough room for a pointer to the function, and
1283 /* XXX, FIXME: The stack space allocated this way is too long lived,
1284 but there is no allocation routine that allocates at the level of
1285 the last binding contour. */
1286 buf = assign_stack_local (BLKmode,
1287 GET_MODE_SIZE (Pmode)*(size+1),
1290 buf = change_address (buf, Pmode, NULL_RTX);
1292 /* Store dcc into the first word of the newly allocated buffer. */
1294 dcc = get_dynamic_cleanup_chain ();
1295 emit_move_insn (buf, dcc);
1297 /* Store func and arg into the cleanup list element. */
1299 new_func = gen_rtx_MEM (Pmode, plus_constant (XEXP (buf, 0),
1300 GET_MODE_SIZE (Pmode)));
1301 new_arg = gen_rtx_MEM (Pmode, plus_constant (XEXP (buf, 0),
1302 GET_MODE_SIZE (Pmode)*2));
1303 x = expand_expr (func, new_func, Pmode, 0);
1305 emit_move_insn (new_func, x);
1307 x = expand_expr (arg, new_arg, Pmode, 0);
1309 emit_move_insn (new_arg, x);
1311 /* Update the cleanup chain. */
1313 x = force_operand (XEXP (buf, 0), dcc);
1315 emit_move_insn (dcc, x);
1318 /* Emit RTL to start a dynamic handler on the EH runtime dynamic
1319 handler stack. This should only be used by expand_eh_region_start
1320 or expand_eh_region_start_tree. */
1323 start_dynamic_handler ()
1329 #ifndef DONT_USE_BUILTIN_SETJMP
1330 /* The number of Pmode words for the setjmp buffer, when using the
1331 builtin setjmp/longjmp, see expand_builtin, case BUILT_IN_LONGJMP. */
1332 /* We use 2 words here before calling expand_builtin_setjmp.
1333 expand_builtin_setjmp uses 2 words, and then calls emit_stack_save.
1334 emit_stack_save needs space of size STACK_SAVEAREA_MODE (SAVE_NONLOCAL).
1335 Subtract one, because the assign_stack_local call below adds 1. */
1336 size = (2 + 2 + (GET_MODE_SIZE (STACK_SAVEAREA_MODE (SAVE_NONLOCAL))
1337 / GET_MODE_SIZE (Pmode))
1341 size = JMP_BUF_SIZE;
1343 /* Should be large enough for most systems, if it is not,
1344 JMP_BUF_SIZE should be defined with the proper value. It will
1345 also tend to be larger than necessary for most systems, a more
1346 optimal port will define JMP_BUF_SIZE. */
1347 size = FIRST_PSEUDO_REGISTER+2;
1350 /* XXX, FIXME: The stack space allocated this way is too long lived,
1351 but there is no allocation routine that allocates at the level of
1352 the last binding contour. */
1353 arg = assign_stack_local (BLKmode,
1354 GET_MODE_SIZE (Pmode)*(size+1),
1357 arg = change_address (arg, Pmode, NULL_RTX);
1359 /* Store dhc into the first word of the newly allocated buffer. */
1361 dhc = get_dynamic_handler_chain ();
1362 dcc = gen_rtx_MEM (Pmode, plus_constant (XEXP (arg, 0),
1363 GET_MODE_SIZE (Pmode)));
1364 emit_move_insn (arg, dhc);
1366 /* Zero out the start of the cleanup chain. */
1367 emit_move_insn (dcc, const0_rtx);
1369 /* The jmpbuf starts two words into the area allocated. */
1370 buf = plus_constant (XEXP (arg, 0), GET_MODE_SIZE (Pmode)*2);
1372 #ifdef DONT_USE_BUILTIN_SETJMP
1375 x = emit_library_call_value (setjmp_libfunc, NULL_RTX, LCT_CONST,
1376 TYPE_MODE (integer_type_node), 1,
1378 /* If we come back here for a catch, transfer control to the handler. */
1379 jumpif_rtx (x, ehstack.top->entry->exception_handler_label);
1382 expand_builtin_setjmp_setup (buf,
1383 ehstack.top->entry->exception_handler_label);
1386 /* We are committed to this, so update the handler chain. */
1388 emit_move_insn (dhc, force_operand (XEXP (arg, 0), NULL_RTX));
1391 /* Start an exception handling region for the given cleanup action.
1392 All instructions emitted after this point are considered to be part
1393 of the region until expand_eh_region_end is invoked. CLEANUP is
1394 the cleanup action to perform. The return value is true if the
1395 exception region was optimized away. If that case,
1396 expand_eh_region_end does not need to be called for this cleanup,
1399 This routine notices one particular common case in C++ code
1400 generation, and optimizes it so as to not need the exception
1401 region. It works by creating a dynamic cleanup action, instead of
1402 a using an exception region. */
1405 expand_eh_region_start_tree (decl, cleanup)
1409 /* This is the old code. */
1413 /* The optimization only applies to actions protected with
1414 terminate, and only applies if we are using the setjmp/longjmp
1416 if (exceptions_via_longjmp
1417 && protect_cleanup_actions_with_terminate)
1422 /* Ignore any UNSAVE_EXPR. */
1423 if (TREE_CODE (cleanup) == UNSAVE_EXPR)
1424 cleanup = TREE_OPERAND (cleanup, 0);
1426 /* Further, it only applies if the action is a call, if there
1427 are 2 arguments, and if the second argument is 2. */
1429 if (TREE_CODE (cleanup) == CALL_EXPR
1430 && (args = TREE_OPERAND (cleanup, 1))
1431 && (func = TREE_OPERAND (cleanup, 0))
1432 && (arg = TREE_VALUE (args))
1433 && (args = TREE_CHAIN (args))
1435 /* is the second argument 2? */
1436 && TREE_CODE (TREE_VALUE (args)) == INTEGER_CST
1437 && compare_tree_int (TREE_VALUE (args), 2) == 0
1439 /* Make sure there are no other arguments. */
1440 && TREE_CHAIN (args) == NULL_TREE)
1442 /* Arrange for returns and gotos to pop the entry we make on the
1443 dynamic cleanup stack. */
1444 expand_dcc_cleanup (decl);
1445 start_dynamic_cleanup (func, arg);
1450 expand_eh_region_start_for_decl (decl);
1451 ehstack.top->entry->finalization = cleanup;
1456 /* Just like expand_eh_region_start, except if a cleanup action is
1457 entered on the cleanup chain, the TREE_PURPOSE of the element put
1458 on the chain is DECL. DECL should be the associated VAR_DECL, if
1459 any, otherwise it should be NULL_TREE. */
1462 expand_eh_region_start_for_decl (decl)
1467 /* This is the old code. */
1471 /* We need a new block to record the start and end of the
1472 dynamic handler chain. We also want to prevent jumping into
1474 expand_start_bindings (2);
1476 /* But we don't need or want a new temporary level. */
1479 /* Mark this block as created by expand_eh_region_start. This
1480 is so that we can pop the block with expand_end_bindings
1482 mark_block_as_eh_region ();
1484 if (exceptions_via_longjmp)
1486 /* Arrange for returns and gotos to pop the entry we make on the
1487 dynamic handler stack. */
1488 expand_dhc_cleanup (decl);
1491 push_eh_entry (&ehstack);
1492 note = emit_note (NULL_PTR, NOTE_INSN_EH_REGION_BEG);
1493 NOTE_EH_HANDLER (note)
1494 = CODE_LABEL_NUMBER (ehstack.top->entry->exception_handler_label);
1495 if (exceptions_via_longjmp)
1496 start_dynamic_handler ();
1499 /* Start an exception handling region. All instructions emitted after
1500 this point are considered to be part of the region until
1501 expand_eh_region_end is invoked. */
1504 expand_eh_region_start ()
1506 expand_eh_region_start_for_decl (NULL_TREE);
1509 /* End an exception handling region. The information about the region
1510 is found on the top of ehstack.
1512 HANDLER is either the cleanup for the exception region, or if we're
1513 marking the end of a try block, HANDLER is integer_zero_node.
1515 HANDLER will be transformed to rtl when expand_leftover_cleanups
1519 expand_eh_region_end (handler)
1522 struct eh_entry *entry;
1523 struct eh_node *node;
1530 entry = pop_eh_entry (&ehstack);
1532 note = emit_note (NULL_PTR, NOTE_INSN_EH_REGION_END);
1533 ret = NOTE_EH_HANDLER (note)
1534 = CODE_LABEL_NUMBER (entry->exception_handler_label);
1535 if (exceptions_via_longjmp == 0 && ! flag_new_exceptions
1536 /* We share outer_context between regions; only emit it once. */
1537 && INSN_UID (entry->outer_context) == 0)
1541 label = gen_label_rtx ();
1544 /* Emit a label marking the end of this exception region that
1545 is used for rethrowing into the outer context. */
1546 emit_label (entry->outer_context);
1547 expand_internal_throw ();
1552 entry->finalization = handler;
1554 /* create region entry in final exception table */
1555 r = new_eh_region_entry (NOTE_EH_HANDLER (note), entry->rethrow_label);
1557 enqueue_eh_entry (ehqueue, entry);
1559 /* If we have already started ending the bindings, don't recurse. */
1560 if (is_eh_region ())
1562 /* Because we don't need or want a new temporary level and
1563 because we didn't create one in expand_eh_region_start,
1564 create a fake one now to avoid removing one in
1565 expand_end_bindings. */
1568 mark_block_as_not_eh_region ();
1570 expand_end_bindings (NULL_TREE, 0, 0);
1573 /* Go through the goto handlers in the queue, emitting their
1574 handlers if we now have enough information to do so. */
1575 for (node = ehqueue->head; node; node = node->chain)
1576 if (node->entry->goto_entry_p
1577 && node->entry->outer_context == entry->rethrow_label)
1578 emit_cleanup_handler (node->entry);
1580 /* We can't emit handlers for goto entries until their scopes are
1581 complete because we don't know where they need to rethrow to,
1583 if (entry->finalization != integer_zero_node
1584 && (!entry->goto_entry_p
1585 || find_func_region_from_symbol (entry->outer_context) != -1))
1586 emit_cleanup_handler (entry);
1589 /* End the EH region for a goto fixup. We only need them in the region-based
1593 expand_fixup_region_start ()
1595 if (! doing_eh (0) || exceptions_via_longjmp)
1598 expand_eh_region_start ();
1599 /* Mark this entry as the entry for a goto. */
1600 ehstack.top->entry->goto_entry_p = 1;
1603 /* End the EH region for a goto fixup. CLEANUP is the cleanup we just
1604 expanded; to avoid running it twice if it throws, we look through the
1605 ehqueue for a matching region and rethrow from its outer_context. */
1608 expand_fixup_region_end (cleanup)
1611 struct eh_node *node;
1614 if (! doing_eh (0) || exceptions_via_longjmp)
1617 for (node = ehstack.top; node && node->entry->finalization != cleanup; )
1620 for (node = ehqueue->head; node && node->entry->finalization != cleanup; )
1625 /* If the outer context label has not been issued yet, we don't want
1626 to issue it as a part of this region, unless this is the
1627 correct region for the outer context. If we did, then the label for
1628 the outer context will be WITHIN the begin/end labels,
1629 and we could get an infinte loop when it tried to rethrow, or just
1630 generally incorrect execution following a throw. */
1632 if (flag_new_exceptions)
1635 dont_issue = ((INSN_UID (node->entry->outer_context) == 0)
1636 && (ehstack.top->entry != node->entry));
1638 ehstack.top->entry->outer_context = node->entry->outer_context;
1640 /* Since we are rethrowing to the OUTER region, we know we don't need
1641 a jump around sequence for this region, so we'll pretend the outer
1642 context label has been issued by setting INSN_UID to 1, then clearing
1643 it again afterwards. */
1646 INSN_UID (node->entry->outer_context) = 1;
1648 /* Just rethrow. size_zero_node is just a NOP. */
1649 expand_eh_region_end (size_zero_node);
1652 INSN_UID (node->entry->outer_context) = 0;
1655 /* If we are using the setjmp/longjmp EH codegen method, we emit a
1656 call to __sjthrow. Otherwise, we emit a call to __throw. */
1661 if (exceptions_via_longjmp)
1663 emit_library_call (sjthrow_libfunc, 0, VOIDmode, 0);
1667 #ifdef JUMP_TO_THROW
1668 emit_indirect_jump (throw_libfunc);
1670 emit_library_call (throw_libfunc, 0, VOIDmode, 0);
1676 /* Throw the current exception. If appropriate, this is done by jumping
1677 to the next handler. */
1680 expand_internal_throw ()
1685 /* Called from expand_exception_blocks and expand_end_catch_block to
1686 emit any pending handlers/cleanups queued from expand_eh_region_end. */
1689 expand_leftover_cleanups ()
1691 struct eh_entry *entry;
1693 for (entry = dequeue_eh_entry (ehqueue);
1695 entry = dequeue_eh_entry (ehqueue))
1697 /* A leftover try block. Shouldn't be one here. */
1698 if (entry->finalization == integer_zero_node)
1705 /* Called at the start of a block of try statements. */
1707 expand_start_try_stmts ()
1712 expand_eh_region_start ();
1715 /* Called to begin a catch clause. The parameter is the object which
1716 will be passed to the runtime type check routine. */
1718 start_catch_handler (rtime)
1722 int insn_region_num;
1723 int eh_region_entry;
1728 handler_label = catchstack.top->entry->exception_handler_label;
1729 insn_region_num = CODE_LABEL_NUMBER (handler_label);
1730 eh_region_entry = find_func_region (insn_region_num);
1732 /* If we've already issued this label, pick a new one */
1733 if (catchstack.top->entry->label_used)
1734 handler_label = gen_exception_label ();
1736 catchstack.top->entry->label_used = 1;
1738 receive_exception_label (handler_label);
1740 add_new_handler (eh_region_entry, get_new_handler (handler_label, rtime));
1742 if (flag_new_exceptions && ! exceptions_via_longjmp)
1745 /* Under the old mechanism, as well as setjmp/longjmp, we need to
1746 issue code to compare 'rtime' to the value in eh_info, via the
1747 matching function in eh_info. If its is false, we branch around
1748 the handler we are about to issue. */
1750 if (rtime != NULL_TREE && rtime != CATCH_ALL_TYPE)
1752 rtx call_rtx, rtime_address;
1754 if (catchstack.top->entry->false_label != NULL_RTX)
1756 error ("Never issued previous false_label");
1759 catchstack.top->entry->false_label = gen_exception_label ();
1761 rtime_address = expand_expr (rtime, NULL_RTX, Pmode, EXPAND_INITIALIZER);
1762 #ifdef POINTERS_EXTEND_UNSIGNED
1763 rtime_address = convert_memory_address (Pmode, rtime_address);
1765 rtime_address = force_reg (Pmode, rtime_address);
1767 /* Now issue the call, and branch around handler if needed */
1768 call_rtx = emit_library_call_value (eh_rtime_match_libfunc, NULL_RTX,
1770 TYPE_MODE (integer_type_node),
1771 1, rtime_address, Pmode);
1773 /* Did the function return true? */
1774 emit_cmp_and_jump_insns (call_rtx, const0_rtx, EQ, NULL_RTX,
1775 GET_MODE (call_rtx), 0, 0,
1776 catchstack.top->entry->false_label);
1780 /* Called to end a catch clause. If we aren't using the new exception
1781 model tabel mechanism, we need to issue the branch-around label
1782 for the end of the catch block. */
1785 end_catch_handler ()
1790 if (flag_new_exceptions && ! exceptions_via_longjmp)
1796 /* A NULL label implies the catch clause was a catch all or cleanup */
1797 if (catchstack.top->entry->false_label == NULL_RTX)
1800 emit_label (catchstack.top->entry->false_label);
1801 catchstack.top->entry->false_label = NULL_RTX;
1804 /* Save away the current ehqueue. */
1810 q = (struct eh_queue *) xcalloc (1, sizeof (struct eh_queue));
1815 /* Restore a previously pushed ehqueue. */
1821 expand_leftover_cleanups ();
1827 /* Emit the handler specified by ENTRY. */
1830 emit_cleanup_handler (entry)
1831 struct eh_entry *entry;
1836 /* Since the cleanup could itself contain try-catch blocks, we
1837 squirrel away the current queue and replace it when we are done
1838 with this function. */
1841 /* Put these handler instructions in a sequence. */
1842 do_pending_stack_adjust ();
1845 /* Emit the label for the cleanup handler for this region, and
1846 expand the code for the handler.
1848 Note that a catch region is handled as a side-effect here; for a
1849 try block, entry->finalization will contain integer_zero_node, so
1850 no code will be generated in the expand_expr call below. But, the
1851 label for the handler will still be emitted, so any code emitted
1852 after this point will end up being the handler. */
1854 receive_exception_label (entry->exception_handler_label);
1856 /* register a handler for this cleanup region */
1857 add_new_handler (find_func_region (CODE_LABEL_NUMBER (entry->exception_handler_label)),
1858 get_new_handler (entry->exception_handler_label, NULL));
1860 /* And now generate the insns for the cleanup handler. */
1861 expand_expr (entry->finalization, const0_rtx, VOIDmode, 0);
1863 prev = get_last_insn ();
1864 if (prev == NULL || GET_CODE (prev) != BARRIER)
1865 /* Code to throw out to outer context when we fall off end of the
1866 handler. We can't do this here for catch blocks, so it's done
1867 in expand_end_all_catch instead. */
1868 expand_rethrow (entry->outer_context);
1870 /* Finish this sequence. */
1871 do_pending_stack_adjust ();
1872 handler_insns = get_insns ();
1875 /* And add it to the CATCH_CLAUSES. */
1876 push_to_full_sequence (catch_clauses, catch_clauses_last);
1877 emit_insns (handler_insns);
1878 end_full_sequence (&catch_clauses, &catch_clauses_last);
1880 /* Now we've left the handler. */
1884 /* Generate RTL for the start of a group of catch clauses.
1886 It is responsible for starting a new instruction sequence for the
1887 instructions in the catch block, and expanding the handlers for the
1888 internally-generated exception regions nested within the try block
1889 corresponding to this catch block. */
1892 expand_start_all_catch ()
1894 struct eh_entry *entry;
1901 outer_context = ehstack.top->entry->outer_context;
1903 /* End the try block. */
1904 expand_eh_region_end (integer_zero_node);
1906 emit_line_note (input_filename, lineno);
1907 label = build_decl (LABEL_DECL, NULL_TREE, NULL_TREE);
1909 /* The label for the exception handling block that we will save.
1910 This is Lresume in the documentation. */
1911 expand_label (label);
1913 /* Push the label that points to where normal flow is resumed onto
1914 the top of the label stack. */
1915 push_label_entry (&caught_return_label_stack, NULL_RTX, label);
1917 /* Start a new sequence for all the catch blocks. We will add this
1918 to the global sequence catch_clauses when we have completed all
1919 the handlers in this handler-seq. */
1922 /* Throw away entries in the queue that we won't need anymore. We
1923 need entries for regions that have ended but to which there might
1924 still be gotos pending. */
1925 for (entry = dequeue_eh_entry (ehqueue);
1926 entry->finalization != integer_zero_node;
1927 entry = dequeue_eh_entry (ehqueue))
1930 /* At this point, all the cleanups are done, and the ehqueue now has
1931 the current exception region at its head. We dequeue it, and put it
1932 on the catch stack. */
1933 push_entry (&catchstack, entry);
1935 /* If we are not doing setjmp/longjmp EH, because we are reordered
1936 out of line, we arrange to rethrow in the outer context. We need to
1937 do this because we are not physically within the region, if any, that
1938 logically contains this catch block. */
1939 if (! exceptions_via_longjmp)
1941 expand_eh_region_start ();
1942 ehstack.top->entry->outer_context = outer_context;
1947 /* Finish up the catch block. At this point all the insns for the
1948 catch clauses have already been generated, so we only have to add
1949 them to the catch_clauses list. We also want to make sure that if
1950 we fall off the end of the catch clauses that we rethrow to the
1954 expand_end_all_catch ()
1956 rtx new_catch_clause;
1957 struct eh_entry *entry;
1962 /* Dequeue the current catch clause region. */
1963 entry = pop_eh_entry (&catchstack);
1966 if (! exceptions_via_longjmp)
1968 rtx outer_context = ehstack.top->entry->outer_context;
1970 /* Finish the rethrow region. size_zero_node is just a NOP. */
1971 expand_eh_region_end (size_zero_node);
1972 /* New exceptions handling models will never have a fall through
1973 of a catch clause */
1974 if (!flag_new_exceptions)
1975 expand_rethrow (outer_context);
1978 expand_rethrow (NULL_RTX);
1980 /* Code to throw out to outer context, if we fall off end of catch
1981 handlers. This is rethrow (Lresume, same id, same obj) in the
1982 documentation. We use Lresume because we know that it will throw
1983 to the correct context.
1985 In other words, if the catch handler doesn't exit or return, we
1986 do a "throw" (using the address of Lresume as the point being
1987 thrown from) so that the outer EH region can then try to process
1990 /* Now we have the complete catch sequence. */
1991 new_catch_clause = get_insns ();
1994 /* This level of catch blocks is done, so set up the successful
1995 catch jump label for the next layer of catch blocks. */
1996 pop_label_entry (&caught_return_label_stack);
1997 pop_label_entry (&outer_context_label_stack);
1999 /* Add the new sequence of catches to the main one for this function. */
2000 push_to_full_sequence (catch_clauses, catch_clauses_last);
2001 emit_insns (new_catch_clause);
2002 end_full_sequence (&catch_clauses, &catch_clauses_last);
2004 /* Here we fall through into the continuation code. */
2007 /* Rethrow from the outer context LABEL. */
2010 expand_rethrow (label)
2013 if (exceptions_via_longjmp)
2016 if (flag_new_exceptions)
2020 if (label == NULL_RTX)
2021 label = last_rethrow_symbol;
2022 emit_library_call (rethrow_libfunc, 0, VOIDmode, 1, label, Pmode);
2023 region = find_func_region (eh_region_from_symbol (label));
2024 /* If the region is -1, it doesn't exist yet. We shouldn't be
2025 trying to rethrow there yet. */
2028 function_eh_regions[region].rethrow_ref = 1;
2030 /* Search backwards for the actual call insn. */
2031 insn = get_last_insn ();
2032 while (GET_CODE (insn) != CALL_INSN)
2033 insn = PREV_INSN (insn);
2034 delete_insns_since (insn);
2036 /* Mark the label/symbol on the call. */
2037 REG_NOTES (insn) = gen_rtx_EXPR_LIST (REG_EH_RETHROW, label,
2045 /* Begin a region that will contain entries created with
2046 add_partial_entry. */
2049 begin_protect_partials ()
2051 /* Push room for a new list. */
2052 protect_list = tree_cons (NULL_TREE, NULL_TREE, protect_list);
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 handler = make_node (RTL_EXPR);
2093 TREE_TYPE (handler) = void_type_node;
2094 RTL_EXPR_RTL (handler) = const0_rtx;
2095 TREE_SIDE_EFFECTS (handler) = 1;
2096 start_sequence_for_rtl_expr (handler);
2098 emit_library_call (terminate_libfunc, 0, VOIDmode, 0);
2101 RTL_EXPR_SEQUENCE (handler) = get_insns ();
2104 result = build (TRY_CATCH_EXPR, TREE_TYPE (e), e, handler);
2105 TREE_SIDE_EFFECTS (result) = TREE_SIDE_EFFECTS (e);
2106 TREE_THIS_VOLATILE (result) = TREE_THIS_VOLATILE (e);
2107 TREE_READONLY (result) = TREE_READONLY (e);
2115 /* The exception table that we build that is used for looking up and
2116 dispatching exceptions, the current number of entries, and its
2117 maximum size before we have to extend it.
2119 The number in eh_table is the code label number of the exception
2120 handler for the region. This is added by add_eh_table_entry and
2121 used by output_exception_table_entry. */
2123 static int *eh_table = NULL;
2124 static int eh_table_size = 0;
2125 static int eh_table_max_size = 0;
2127 /* Note the need for an exception table entry for region N. If we
2128 don't need to output an explicit exception table, avoid all of the
2131 Called from final_scan_insn when a NOTE_INSN_EH_REGION_BEG is seen.
2132 (Or NOTE_INSN_EH_REGION_END sometimes)
2133 N is the NOTE_EH_HANDLER of the note, which comes from the code
2134 label number of the exception handler for the region. */
2137 add_eh_table_entry (n)
2140 #ifndef OMIT_EH_TABLE
2141 if (eh_table_size >= eh_table_max_size)
2145 eh_table_max_size += eh_table_max_size>>1;
2147 if (eh_table_max_size < 0)
2150 eh_table = (int *) xrealloc (eh_table,
2151 eh_table_max_size * sizeof (int));
2155 eh_table_max_size = 252;
2156 eh_table = (int *) xmalloc (eh_table_max_size * sizeof (int));
2159 eh_table[eh_table_size++] = n;
2161 if (flag_new_exceptions)
2163 /* We will output the exception table late in the compilation. That
2164 references type_info objects which should have already been output
2165 by that time. We explicitly mark those objects as being
2166 referenced now so we know to emit them. */
2167 struct handler_info *handler = get_first_handler (n);
2169 for (; handler; handler = handler->next)
2170 if (handler->type_info && handler->type_info != CATCH_ALL_TYPE)
2172 tree tinfo = (tree)handler->type_info;
2174 tinfo = TREE_OPERAND (tinfo, 0);
2175 TREE_SYMBOL_REFERENCED (DECL_ASSEMBLER_NAME (tinfo)) = 1;
2181 /* Return a non-zero value if we need to output an exception table.
2183 On some platforms, we don't have to output a table explicitly.
2184 This routine doesn't mean we don't have one. */
2187 exception_table_p ()
2195 /* Output the entry of the exception table corresponding to the
2196 exception region numbered N to file FILE.
2198 N is the code label number corresponding to the handler of the
2202 output_exception_table_entry (file, n)
2208 struct handler_info *handler = get_first_handler (n);
2209 int index = find_func_region (n);
2212 /* Form and emit the rethrow label, if needed */
2213 if (flag_new_exceptions
2214 && (handler || function_eh_regions[index].rethrow_ref))
2215 rethrow = function_eh_regions[index].rethrow_label;
2219 if (function_eh_regions[index].emitted)
2221 function_eh_regions[index].emitted = 1;
2223 for ( ; handler != NULL || rethrow != NULL_RTX; handler = handler->next)
2225 /* rethrow label should indicate the LAST entry for a region */
2226 if (rethrow != NULL_RTX && (handler == NULL || handler->next == NULL))
2228 ASM_GENERATE_INTERNAL_LABEL (buf, "LRTH", n);
2229 assemble_eh_label(buf);
2233 ASM_GENERATE_INTERNAL_LABEL (buf, "LEHB", n);
2234 sym = gen_rtx_SYMBOL_REF (Pmode, buf);
2235 assemble_eh_integer (sym, POINTER_SIZE / BITS_PER_UNIT, 1);
2237 ASM_GENERATE_INTERNAL_LABEL (buf, "LEHE", n);
2238 sym = gen_rtx_SYMBOL_REF (Pmode, buf);
2239 assemble_eh_integer (sym, POINTER_SIZE / BITS_PER_UNIT, 1);
2241 if (handler == NULL)
2242 assemble_eh_integer (GEN_INT (0), POINTER_SIZE / BITS_PER_UNIT, 1);
2245 ASM_GENERATE_INTERNAL_LABEL (buf, "L", handler->handler_number);
2246 sym = gen_rtx_SYMBOL_REF (Pmode, buf);
2247 assemble_eh_integer (sym, POINTER_SIZE / BITS_PER_UNIT, 1);
2250 if (flag_new_exceptions)
2252 if (handler == NULL || handler->type_info == NULL)
2253 assemble_eh_integer (const0_rtx, POINTER_SIZE / BITS_PER_UNIT, 1);
2255 if (handler->type_info == CATCH_ALL_TYPE)
2256 assemble_eh_integer (GEN_INT (CATCH_ALL_TYPE),
2257 POINTER_SIZE / BITS_PER_UNIT, 1);
2259 output_constant ((tree)(handler->type_info),
2260 POINTER_SIZE / BITS_PER_UNIT);
2262 putc ('\n', file); /* blank line */
2263 /* We only output the first label under the old scheme */
2264 if (! flag_new_exceptions || handler == NULL)
2269 /* Output the exception table if we have and need one. */
2271 static short language_code = 0;
2272 static short version_code = 0;
2274 /* This routine will set the language code for exceptions. */
2276 set_exception_lang_code (code)
2279 language_code = code;
2282 /* This routine will set the language version code for exceptions. */
2284 set_exception_version_code (code)
2287 version_code = code;
2290 /* Free the EH table structures. */
2292 free_exception_table ()
2296 clear_function_eh_region ();
2299 /* Output the common content of an exception table. */
2301 output_exception_table_data ()
2305 extern FILE *asm_out_file;
2307 if (flag_new_exceptions)
2309 assemble_eh_integer (GEN_INT (NEW_EH_RUNTIME),
2310 POINTER_SIZE / BITS_PER_UNIT, 1);
2311 assemble_eh_integer (GEN_INT (language_code), 2 , 1);
2312 assemble_eh_integer (GEN_INT (version_code), 2 , 1);
2314 /* Add enough padding to make sure table aligns on a pointer boundry. */
2315 i = GET_MODE_ALIGNMENT (ptr_mode) / BITS_PER_UNIT - 4;
2316 for ( ; i < 0; i = i + GET_MODE_ALIGNMENT (ptr_mode) / BITS_PER_UNIT)
2319 assemble_eh_integer (const0_rtx, i , 1);
2321 /* Generate the label for offset calculations on rethrows. */
2322 ASM_GENERATE_INTERNAL_LABEL (buf, "LRTH", 0);
2323 assemble_eh_label(buf);
2326 for (i = 0; i < eh_table_size; ++i)
2327 output_exception_table_entry (asm_out_file, eh_table[i]);
2331 /* Output an exception table for the entire compilation unit. */
2333 output_exception_table ()
2336 extern FILE *asm_out_file;
2338 if (! doing_eh (0) || ! eh_table)
2341 exception_section ();
2343 /* Beginning marker for table. */
2344 assemble_eh_align (GET_MODE_ALIGNMENT (ptr_mode));
2345 assemble_eh_label ("__EXCEPTION_TABLE__");
2347 output_exception_table_data ();
2349 /* Ending marker for table. */
2350 /* Generate the label for end of table. */
2351 ASM_GENERATE_INTERNAL_LABEL (buf, "LRTH", CODE_LABEL_NUMBER (final_rethrow));
2352 assemble_eh_label(buf);
2353 assemble_eh_integer (constm1_rtx, POINTER_SIZE / BITS_PER_UNIT, 1);
2355 /* For binary compatibility, the old __throw checked the second
2356 position for a -1, so we should output at least 2 -1's */
2357 if (! flag_new_exceptions)
2358 assemble_eh_integer (constm1_rtx, POINTER_SIZE / BITS_PER_UNIT, 1);
2360 putc ('\n', asm_out_file); /* blank line */
2363 /* Used by the ia64 unwind format to output data for an individual
2366 output_function_exception_table ()
2368 extern FILE *asm_out_file;
2370 if (! doing_eh (0) || ! eh_table)
2373 #ifdef HANDLER_SECTION
2377 output_exception_table_data ();
2379 /* Ending marker for table. */
2380 assemble_eh_integer (constm1_rtx, POINTER_SIZE / BITS_PER_UNIT, 1);
2382 putc ('\n', asm_out_file); /* blank line */
2386 /* Emit code to get EH context.
2388 We have to scan thru the code to find possible EH context registers.
2389 Inlined functions may use it too, and thus we'll have to be able
2392 This is done only if using exceptions_via_longjmp. */
2403 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
2404 if (GET_CODE (insn) == INSN
2405 && GET_CODE (PATTERN (insn)) == USE)
2407 rtx reg = find_reg_note (insn, REG_EH_CONTEXT, 0);
2414 /* If this is the first use insn, emit the call here. This
2415 will always be at the top of our function, because if
2416 expand_inline_function notices a REG_EH_CONTEXT note, it
2417 adds a use insn to this function as well. */
2419 ehc = call_get_eh_context ();
2421 emit_move_insn (XEXP (reg, 0), ehc);
2422 insns = get_insns ();
2425 emit_insns_before (insns, insn);
2430 /* Scan the insn chain F and build a list of handler labels. The
2431 resulting list is placed in the global variable exception_handler_labels. */
2434 find_exception_handler_labels_1 (f)
2439 /* For each start of a region, add its label to the list. */
2441 for (insn = f; insn; insn = NEXT_INSN (insn))
2443 struct handler_info* ptr;
2444 if (GET_CODE (insn) == NOTE
2445 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG)
2447 ptr = get_first_handler (NOTE_EH_HANDLER (insn));
2448 for ( ; ptr; ptr = ptr->next)
2450 /* make sure label isn't in the list already */
2452 for (x = exception_handler_labels; x; x = XEXP (x, 1))
2453 if (XEXP (x, 0) == ptr->handler_label)
2456 exception_handler_labels = gen_rtx_EXPR_LIST (VOIDmode,
2457 ptr->handler_label, exception_handler_labels);
2460 else if (GET_CODE (insn) == CALL_INSN
2461 && GET_CODE (PATTERN (insn)) == CALL_PLACEHOLDER)
2463 find_exception_handler_labels_1 (XEXP (PATTERN (insn), 0));
2464 find_exception_handler_labels_1 (XEXP (PATTERN (insn), 1));
2465 find_exception_handler_labels_1 (XEXP (PATTERN (insn), 2));
2470 /* Scan the current insns and build a list of handler labels. The
2471 resulting list is placed in the global variable exception_handler_labels.
2473 It is called after the last exception handling region is added to
2474 the current function (when the rtl is almost all built for the
2475 current function) and before the jump optimization pass. */
2477 find_exception_handler_labels ()
2479 exception_handler_labels = NULL_RTX;
2481 /* If we aren't doing exception handling, there isn't much to check. */
2485 find_exception_handler_labels_1 (get_insns ());
2488 /* Return a value of 1 if the parameter label number is an exception handler
2489 label. Return 0 otherwise. */
2492 is_exception_handler_label (lab)
2496 for (x = exception_handler_labels ; x ; x = XEXP (x, 1))
2497 if (lab == CODE_LABEL_NUMBER (XEXP (x, 0)))
2502 /* Perform sanity checking on the exception_handler_labels list.
2504 Can be called after find_exception_handler_labels is called to
2505 build the list of exception handlers for the current function and
2506 before we finish processing the current function. */
2509 check_exception_handler_labels ()
2513 /* If we aren't doing exception handling, there isn't much to check. */
2517 /* Make sure there is no more than 1 copy of a label */
2518 for (insn = exception_handler_labels; insn; insn = XEXP (insn, 1))
2521 for (insn2 = exception_handler_labels; insn2; insn2 = XEXP (insn2, 1))
2522 if (XEXP (insn, 0) == XEXP (insn2, 0))
2525 warning ("Counted %d copies of EH region %d in list.\n", count,
2526 CODE_LABEL_NUMBER (insn));
2531 /* Mark the children of NODE for GC. */
2535 struct eh_node *node;
2541 ggc_mark_rtx (node->entry->outer_context);
2542 ggc_mark_rtx (node->entry->exception_handler_label);
2543 ggc_mark_tree (node->entry->finalization);
2544 ggc_mark_rtx (node->entry->false_label);
2545 ggc_mark_rtx (node->entry->rethrow_label);
2547 node = node ->chain;
2551 /* Mark S for GC. */
2558 mark_eh_node (s->top);
2561 /* Mark Q for GC. */
2569 mark_eh_node (q->head);
2574 /* Mark NODE for GC. A label_node contains a union containing either
2575 a tree or an rtx. This label_node will contain a tree. */
2578 mark_tree_label_node (node)
2579 struct label_node *node;
2583 ggc_mark_tree (node->u.tlabel);
2588 /* Mark EH for GC. */
2592 struct eh_status *eh;
2597 mark_eh_stack (&eh->x_ehstack);
2598 mark_eh_stack (&eh->x_catchstack);
2599 mark_eh_queue (eh->x_ehqueue);
2600 ggc_mark_rtx (eh->x_catch_clauses);
2602 if (lang_mark_false_label_stack)
2603 (*lang_mark_false_label_stack) (eh->x_false_label_stack);
2604 mark_tree_label_node (eh->x_caught_return_label_stack);
2606 ggc_mark_tree (eh->x_protect_list);
2607 ggc_mark_rtx (eh->ehc);
2608 ggc_mark_rtx (eh->x_eh_return_stub_label);
2611 /* Mark ARG (which is really a struct func_eh_entry**) for GC. */
2614 mark_func_eh_entry (arg)
2617 struct func_eh_entry *fee;
2618 struct handler_info *h;
2621 fee = *((struct func_eh_entry **) arg);
2623 for (i = 0; i < current_func_eh_entry; ++i)
2625 ggc_mark_rtx (fee->rethrow_label);
2626 for (h = fee->handlers; h; h = h->next)
2628 ggc_mark_rtx (h->handler_label);
2629 if (h->type_info != CATCH_ALL_TYPE)
2630 ggc_mark_tree ((tree) h->type_info);
2633 /* Skip to the next entry in the array. */
2638 /* This group of functions initializes the exception handling data
2639 structures at the start of the compilation, initializes the data
2640 structures at the start of a function, and saves and restores the
2641 exception handling data structures for the start/end of a nested
2644 /* Toplevel initialization for EH things. */
2649 first_rethrow_symbol = create_rethrow_ref (0);
2650 final_rethrow = gen_exception_label ();
2651 last_rethrow_symbol = create_rethrow_ref (CODE_LABEL_NUMBER (final_rethrow));
2653 ggc_add_rtx_root (&exception_handler_labels, 1);
2654 ggc_add_rtx_root (&eh_return_context, 1);
2655 ggc_add_rtx_root (&eh_return_stack_adjust, 1);
2656 ggc_add_rtx_root (&eh_return_handler, 1);
2657 ggc_add_rtx_root (&first_rethrow_symbol, 1);
2658 ggc_add_rtx_root (&final_rethrow, 1);
2659 ggc_add_rtx_root (&last_rethrow_symbol, 1);
2660 ggc_add_root (&function_eh_regions, 1, sizeof (function_eh_regions),
2661 mark_func_eh_entry);
2664 /* Initialize the per-function EH information. */
2667 init_eh_for_function ()
2669 cfun->eh = (struct eh_status *) xcalloc (1, sizeof (struct eh_status));
2670 ehqueue = (struct eh_queue *) xcalloc (1, sizeof (struct eh_queue));
2671 eh_return_context = NULL_RTX;
2672 eh_return_stack_adjust = NULL_RTX;
2673 eh_return_handler = NULL_RTX;
2680 free (f->eh->x_ehqueue);
2685 /* This section is for the exception handling specific optimization
2688 /* Determine if the given INSN can throw an exception. */
2694 if (GET_CODE (insn) == INSN
2695 && GET_CODE (PATTERN (insn)) == SEQUENCE)
2696 insn = XVECEXP (PATTERN (insn), 0, 0);
2698 /* Calls can always potentially throw exceptions, unless they have
2699 a REG_EH_REGION note with a value of 0 or less. */
2700 if (GET_CODE (insn) == CALL_INSN)
2702 rtx note = find_reg_note (insn, REG_EH_REGION, NULL_RTX);
2703 if (!note || INTVAL (XEXP (note, 0)) > 0)
2707 if (asynchronous_exceptions)
2709 /* If we wanted asynchronous exceptions, then everything but NOTEs
2710 and CODE_LABELs could throw. */
2711 if (GET_CODE (insn) != NOTE && GET_CODE (insn) != CODE_LABEL)
2718 /* Return nonzero if nothing in this function can throw. */
2721 nothrow_function_p ()
2725 if (! flag_exceptions)
2728 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
2729 if (can_throw (insn))
2731 for (insn = current_function_epilogue_delay_list; insn;
2732 insn = XEXP (insn, 1))
2733 if (can_throw (insn))
2739 /* Scan a exception region looking for the matching end and then
2740 remove it if possible. INSN is the start of the region, N is the
2741 region number, and DELETE_OUTER is to note if anything in this
2744 Regions are removed if they cannot possibly catch an exception.
2745 This is determined by invoking can_throw on each insn within the
2746 region; if can_throw returns true for any of the instructions, the
2747 region can catch an exception, since there is an insn within the
2748 region that is capable of throwing an exception.
2750 Returns the NOTE_INSN_EH_REGION_END corresponding to this region, or
2751 calls abort if it can't find one.
2753 Can abort if INSN is not a NOTE_INSN_EH_REGION_BEGIN, or if N doesn't
2754 correspond to the region number, or if DELETE_OUTER is NULL. */
2757 scan_region (insn, n, delete_outer)
2764 /* Assume we can delete the region. */
2767 /* Can't delete something which is rethrown from. */
2768 if (rethrow_used (n))
2771 if (insn == NULL_RTX
2772 || GET_CODE (insn) != NOTE
2773 || NOTE_LINE_NUMBER (insn) != NOTE_INSN_EH_REGION_BEG
2774 || NOTE_EH_HANDLER (insn) != n
2775 || delete_outer == NULL)
2778 insn = NEXT_INSN (insn);
2780 /* Look for the matching end. */
2781 while (! (GET_CODE (insn) == NOTE
2782 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_END))
2784 /* If anything can throw, we can't remove the region. */
2785 if (delete && can_throw (insn))
2790 /* Watch out for and handle nested regions. */
2791 if (GET_CODE (insn) == NOTE
2792 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG)
2794 insn = scan_region (insn, NOTE_EH_HANDLER (insn), &delete);
2797 insn = NEXT_INSN (insn);
2800 /* The _BEG/_END NOTEs must match and nest. */
2801 if (NOTE_EH_HANDLER (insn) != n)
2804 /* If anything in this exception region can throw, we can throw. */
2809 /* Delete the start and end of the region. */
2810 delete_insn (start);
2813 /* We no longer removed labels here, since flow will now remove any
2814 handler which cannot be called any more. */
2817 /* Only do this part if we have built the exception handler
2819 if (exception_handler_labels)
2821 rtx x, *prev = &exception_handler_labels;
2823 /* Find it in the list of handlers. */
2824 for (x = exception_handler_labels; x; x = XEXP (x, 1))
2826 rtx label = XEXP (x, 0);
2827 if (CODE_LABEL_NUMBER (label) == n)
2829 /* If we are the last reference to the handler,
2831 if (--LABEL_NUSES (label) == 0)
2832 delete_insn (label);
2836 /* Remove it from the list of exception handler
2837 labels, if we are optimizing. If we are not, then
2838 leave it in the list, as we are not really going to
2839 remove the region. */
2840 *prev = XEXP (x, 1);
2847 prev = &XEXP (x, 1);
2855 /* Perform various interesting optimizations for exception handling
2858 We look for empty exception regions and make them go (away). The
2859 jump optimization code will remove the handler if nothing else uses
2863 exception_optimize ()
2868 /* Remove empty regions. */
2869 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
2871 if (GET_CODE (insn) == NOTE
2872 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG)
2874 /* Since scan_region will return the NOTE_INSN_EH_REGION_END
2875 insn, we will indirectly skip through all the insns
2876 inbetween. We are also guaranteed that the value of insn
2877 returned will be valid, as otherwise scan_region won't
2879 insn = scan_region (insn, NOTE_EH_HANDLER (insn), &n);
2884 /* This function determines whether the rethrow labels for any of the
2885 exception regions in the current function are used or not, and set
2886 the reference flag according. */
2889 update_rethrow_references ()
2893 int *saw_region, *saw_rethrow;
2895 if (!flag_new_exceptions)
2898 saw_region = (int *) xcalloc (current_func_eh_entry, sizeof (int));
2899 saw_rethrow = (int *) xcalloc (current_func_eh_entry, sizeof (int));
2901 /* Determine what regions exist, and whether there are any rethrows
2902 from those regions or not. */
2903 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
2904 if (GET_CODE (insn) == CALL_INSN)
2906 rtx note = find_reg_note (insn, REG_EH_RETHROW, NULL_RTX);
2909 region = eh_region_from_symbol (XEXP (note, 0));
2910 region = find_func_region (region);
2911 saw_rethrow[region] = 1;
2915 if (GET_CODE (insn) == NOTE)
2917 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG)
2919 region = find_func_region (NOTE_EH_HANDLER (insn));
2920 saw_region[region] = 1;
2924 /* For any regions we did see, set the referenced flag. */
2925 for (x = 0; x < current_func_eh_entry; x++)
2927 function_eh_regions[x].rethrow_ref = saw_rethrow[x];
2934 /* Various hooks for the DWARF 2 __throw routine. */
2936 /* Do any necessary initialization to access arbitrary stack frames.
2937 On the SPARC, this means flushing the register windows. */
2940 expand_builtin_unwind_init ()
2942 /* Set this so all the registers get saved in our frame; we need to be
2943 able to copy the saved values for any registers from frames we unwind. */
2944 current_function_has_nonlocal_label = 1;
2946 #ifdef SETUP_FRAME_ADDRESSES
2947 SETUP_FRAME_ADDRESSES ();
2951 /* Given a value extracted from the return address register or stack slot,
2952 return the actual address encoded in that value. */
2955 expand_builtin_extract_return_addr (addr_tree)
2958 rtx addr = expand_expr (addr_tree, NULL_RTX, Pmode, 0);
2959 return eh_outer_context (addr);
2962 /* Given an actual address in addr_tree, do any necessary encoding
2963 and return the value to be stored in the return address register or
2964 stack slot so the epilogue will return to that address. */
2967 expand_builtin_frob_return_addr (addr_tree)
2970 rtx addr = expand_expr (addr_tree, NULL_RTX, Pmode, 0);
2971 #ifdef RETURN_ADDR_OFFSET
2972 addr = plus_constant (addr, -RETURN_ADDR_OFFSET);
2977 /* Choose three registers for communication between the main body of
2978 __throw and the epilogue (or eh stub) and the exception handler.
2979 We must do this with hard registers because the epilogue itself
2980 will be generated after reload, at which point we may not reference
2983 The first passes the exception context to the handler. For this
2984 we use the return value register for a void*.
2986 The second holds the stack pointer value to be restored. For this
2987 we use the static chain register if it exists, is different from
2988 the previous, and is call-clobbered; otherwise some arbitrary
2989 call-clobbered register.
2991 The third holds the address of the handler itself. Here we use
2992 some arbitrary call-clobbered register. */
2995 eh_regs (pcontext, psp, pra, outgoing)
2996 rtx *pcontext, *psp, *pra;
2997 int outgoing ATTRIBUTE_UNUSED;
2999 rtx rcontext, rsp, rra;
3003 t = build_pointer_type (void_type_node);
3004 #ifdef FUNCTION_OUTGOING_VALUE
3006 rcontext = FUNCTION_OUTGOING_VALUE (t, current_function_decl);
3009 rcontext = FUNCTION_VALUE (t, current_function_decl);
3011 #ifdef STATIC_CHAIN_REGNUM
3013 rsp = static_chain_incoming_rtx;
3015 rsp = static_chain_rtx;
3016 if (REGNO (rsp) == REGNO (rcontext)
3017 || ! call_used_regs [REGNO (rsp)])
3018 #endif /* STATIC_CHAIN_REGNUM */
3021 if (rsp == NULL_RTX)
3023 for (i = 0; i < FIRST_PSEUDO_REGISTER; ++i)
3024 if (call_used_regs[i] && ! fixed_regs[i] && i != REGNO (rcontext))
3026 if (i == FIRST_PSEUDO_REGISTER)
3029 rsp = gen_rtx_REG (Pmode, i);
3032 for (i = 0; i < FIRST_PSEUDO_REGISTER; ++i)
3033 if (call_used_regs[i] && ! fixed_regs[i]
3034 && i != REGNO (rcontext) && i != REGNO (rsp))
3036 if (i == FIRST_PSEUDO_REGISTER)
3039 rra = gen_rtx_REG (Pmode, i);
3041 *pcontext = rcontext;
3046 /* Retrieve the register which contains the pointer to the eh_context
3047 structure set the __throw. */
3051 get_reg_for_handler ()
3054 reg1 = FUNCTION_VALUE (build_pointer_type (void_type_node),
3055 current_function_decl);
3060 /* Set up the epilogue with the magic bits we'll need to return to the
3061 exception handler. */
3064 expand_builtin_eh_return (context, stack, handler)
3065 tree context, stack, handler;
3067 if (eh_return_context)
3068 error("Duplicate call to __builtin_eh_return");
3071 = copy_to_reg (expand_expr (context, NULL_RTX, VOIDmode, 0));
3072 eh_return_stack_adjust
3073 = copy_to_reg (expand_expr (stack, NULL_RTX, VOIDmode, 0));
3075 = copy_to_reg (expand_expr (handler, NULL_RTX, VOIDmode, 0));
3081 rtx reg1, reg2, reg3;
3082 rtx stub_start, after_stub;
3085 if (!eh_return_context)
3088 current_function_cannot_inline = N_("function uses __builtin_eh_return");
3090 eh_regs (®1, ®2, ®3, 1);
3091 #ifdef POINTERS_EXTEND_UNSIGNED
3092 eh_return_context = convert_memory_address (Pmode, eh_return_context);
3093 eh_return_stack_adjust =
3094 convert_memory_address (Pmode, eh_return_stack_adjust);
3095 eh_return_handler = convert_memory_address (Pmode, eh_return_handler);
3097 emit_move_insn (reg1, eh_return_context);
3098 emit_move_insn (reg2, eh_return_stack_adjust);
3099 emit_move_insn (reg3, eh_return_handler);
3101 /* Talk directly to the target's epilogue code when possible. */
3103 #ifdef HAVE_eh_epilogue
3104 if (HAVE_eh_epilogue)
3106 emit_insn (gen_eh_epilogue (reg1, reg2, reg3));
3111 /* Otherwise, use the same stub technique we had before. */
3113 eh_return_stub_label = stub_start = gen_label_rtx ();
3114 after_stub = gen_label_rtx ();
3116 /* Set the return address to the stub label. */
3118 ra = expand_builtin_return_addr (BUILT_IN_RETURN_ADDRESS,
3119 0, hard_frame_pointer_rtx);
3120 if (GET_CODE (ra) == REG && REGNO (ra) >= FIRST_PSEUDO_REGISTER)
3123 tmp = memory_address (Pmode, gen_rtx_LABEL_REF (Pmode, stub_start));
3124 #ifdef RETURN_ADDR_OFFSET
3125 tmp = plus_constant (tmp, -RETURN_ADDR_OFFSET);
3127 tmp = force_operand (tmp, ra);
3129 emit_move_insn (ra, tmp);
3131 /* Indicate that the registers are in fact used. */
3132 emit_insn (gen_rtx_USE (VOIDmode, reg1));
3133 emit_insn (gen_rtx_USE (VOIDmode, reg2));
3134 emit_insn (gen_rtx_USE (VOIDmode, reg3));
3135 if (GET_CODE (ra) == REG)
3136 emit_insn (gen_rtx_USE (VOIDmode, ra));
3138 /* Generate the stub. */
3140 emit_jump (after_stub);
3141 emit_label (stub_start);
3143 eh_regs (®1, ®2, ®3, 0);
3144 adjust_stack (reg2);
3145 emit_indirect_jump (reg3);
3147 emit_label (after_stub);
3151 /* This contains the code required to verify whether arbitrary instructions
3152 are in the same exception region. */
3154 static int *insn_eh_region = (int *)0;
3155 static int maximum_uid;
3158 set_insn_eh_region (first, region_num)
3165 for (insn = *first; insn; insn = NEXT_INSN (insn))
3167 if ((GET_CODE (insn) == NOTE)
3168 && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG))
3170 rnum = NOTE_EH_HANDLER (insn);
3171 insn_eh_region[INSN_UID (insn)] = rnum;
3172 insn = NEXT_INSN (insn);
3173 set_insn_eh_region (&insn, rnum);
3174 /* Upon return, insn points to the EH_REGION_END of nested region */
3177 insn_eh_region[INSN_UID (insn)] = region_num;
3178 if ((GET_CODE (insn) == NOTE) &&
3179 (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_END))
3185 /* Free the insn table, an make sure it cannot be used again. */
3188 free_insn_eh_region ()
3195 free (insn_eh_region);
3196 insn_eh_region = (int *)0;
3200 /* Initialize the table. max_uid must be calculated and handed into
3201 this routine. If it is unavailable, passing a value of 0 will
3202 cause this routine to calculate it as well. */
3205 init_insn_eh_region (first, max_uid)
3215 free_insn_eh_region();
3218 for (insn = first; insn; insn = NEXT_INSN (insn))
3219 if (INSN_UID (insn) > max_uid) /* find largest UID */
3220 max_uid = INSN_UID (insn);
3222 maximum_uid = max_uid;
3223 insn_eh_region = (int *) xmalloc ((max_uid + 1) * sizeof (int));
3225 set_insn_eh_region (&insn, 0);
3229 /* Check whether 2 instructions are within the same region. */
3232 in_same_eh_region (insn1, insn2)
3235 int ret, uid1, uid2;
3237 /* If no exceptions, instructions are always in same region. */
3241 /* If the table isn't allocated, assume the worst. */
3242 if (!insn_eh_region)
3245 uid1 = INSN_UID (insn1);
3246 uid2 = INSN_UID (insn2);
3248 /* if instructions have been allocated beyond the end, either
3249 the table is out of date, or this is a late addition, or
3250 something... Assume the worst. */
3251 if (uid1 > maximum_uid || uid2 > maximum_uid)
3254 ret = (insn_eh_region[uid1] == insn_eh_region[uid2]);
3259 /* This function will initialize the handler list for a specified block.
3260 It may recursively call itself if the outer block hasn't been processed
3261 yet. At some point in the future we can trim out handlers which we
3262 know cannot be called. (ie, if a block has an INT type handler,
3263 control will never be passed to an outer INT type handler). */
3266 process_nestinfo (block, info, nested_eh_region)
3268 eh_nesting_info *info;
3269 int *nested_eh_region;
3271 handler_info *ptr, *last_ptr = NULL;
3272 int x, y, count = 0;
3274 handler_info **extra_handlers = 0;
3275 int index = info->region_index[block];
3277 /* If we've already processed this block, simply return. */
3278 if (info->num_handlers[index] > 0)
3281 for (ptr = get_first_handler (block); ptr; last_ptr = ptr, ptr = ptr->next)
3284 /* pick up any information from the next outer region. It will already
3285 contain a summary of itself and all outer regions to it. */
3287 if (nested_eh_region [block] != 0)
3289 int nested_index = info->region_index[nested_eh_region[block]];
3290 process_nestinfo (nested_eh_region[block], info, nested_eh_region);
3291 extra = info->num_handlers[nested_index];
3292 extra_handlers = info->handlers[nested_index];
3293 info->outer_index[index] = nested_index;
3296 /* If the last handler is either a CATCH_ALL or a cleanup, then we
3297 won't use the outer ones since we know control will not go past the
3298 catch-all or cleanup. */
3300 if (last_ptr != NULL && (last_ptr->type_info == NULL
3301 || last_ptr->type_info == CATCH_ALL_TYPE))
3304 info->num_handlers[index] = count + extra;
3305 info->handlers[index] = (handler_info **) xmalloc ((count + extra)
3306 * sizeof (handler_info **));
3308 /* First put all our handlers into the list. */
3309 ptr = get_first_handler (block);
3310 for (x = 0; x < count; x++)
3312 info->handlers[index][x] = ptr;
3316 /* Now add all the outer region handlers, if they aren't they same as
3317 one of the types in the current block. We won't worry about
3318 derived types yet, we'll just look for the exact type. */
3319 for (y =0, x = 0; x < extra ; x++)
3323 /* Check to see if we have a type duplication. */
3324 for (i = 0; i < count; i++)
3325 if (info->handlers[index][i]->type_info == extra_handlers[x]->type_info)
3328 /* Record one less handler. */
3329 (info->num_handlers[index])--;
3334 info->handlers[index][y + count] = extra_handlers[x];
3340 /* This function will allocate and initialize an eh_nesting_info structure.
3341 It returns a pointer to the completed data structure. If there are
3342 no exception regions, a NULL value is returned. */
3345 init_eh_nesting_info ()
3347 int *nested_eh_region;
3348 int region_count = 0;
3349 rtx eh_note = NULL_RTX;
3350 eh_nesting_info *info;
3354 if (! flag_exceptions)
3357 info = (eh_nesting_info *) xmalloc (sizeof (eh_nesting_info));
3358 info->region_index = (int *) xcalloc ((max_label_num () + 1), sizeof (int));
3359 nested_eh_region = (int *) xcalloc (max_label_num () + 1, sizeof (int));
3361 /* Create the nested_eh_region list. If indexed with a block number, it
3362 returns the block number of the next outermost region, if any.
3363 We can count the number of regions and initialize the region_index
3364 vector at the same time. */
3365 for (insn = get_insns(); insn; insn = NEXT_INSN (insn))
3367 if (GET_CODE (insn) == NOTE)
3369 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG)
3371 int block = NOTE_EH_HANDLER (insn);
3373 info->region_index[block] = region_count;
3375 nested_eh_region [block] =
3376 NOTE_EH_HANDLER (XEXP (eh_note, 0));
3378 nested_eh_region [block] = 0;
3379 eh_note = gen_rtx_EXPR_LIST (VOIDmode, insn, eh_note);
3381 else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_END)
3382 eh_note = XEXP (eh_note, 1);
3386 /* If there are no regions, wrap it up now. */
3387 if (region_count == 0)
3389 free (info->region_index);
3391 free (nested_eh_region);
3396 info->handlers = (handler_info ***) xcalloc (region_count,
3397 sizeof (handler_info ***));
3398 info->num_handlers = (int *) xcalloc (region_count, sizeof (int));
3399 info->outer_index = (int *) xcalloc (region_count, sizeof (int));
3401 /* Now initialize the handler lists for all exception blocks. */
3402 for (x = 0; x <= max_label_num (); x++)
3404 if (info->region_index[x] != 0)
3405 process_nestinfo (x, info, nested_eh_region);
3407 info->region_count = region_count;
3410 free (nested_eh_region);
3416 /* This function is used to retreive the vector of handlers which
3417 can be reached by a given insn in a given exception region.
3418 BLOCK is the exception block the insn is in.
3419 INFO is the eh_nesting_info structure.
3420 INSN is the (optional) insn within the block. If insn is not NULL_RTX,
3421 it may contain reg notes which modify its throwing behavior, and
3422 these will be obeyed. If NULL_RTX is passed, then we simply return the
3424 HANDLERS is the address of a pointer to a vector of handler_info pointers.
3425 Upon return, this will have the handlers which can be reached by block.
3426 This function returns the number of elements in the handlers vector. */
3429 reachable_handlers (block, info, insn, handlers)
3431 eh_nesting_info *info;
3433 handler_info ***handlers;
3441 index = info->region_index[block];
3443 if (insn && GET_CODE (insn) == CALL_INSN)
3445 /* RETHROWs specify a region number from which we are going to rethrow.
3446 This means we won't pass control to handlers in the specified
3447 region, but rather any region OUTSIDE the specified region.
3448 We accomplish this by setting block to the outer_index of the
3449 specified region. */
3450 rtx note = find_reg_note (insn, REG_EH_RETHROW, NULL_RTX);
3453 index = eh_region_from_symbol (XEXP (note, 0));
3454 index = info->region_index[index];
3456 index = info->outer_index[index];
3460 /* If there is no rethrow, we look for a REG_EH_REGION, and
3461 we'll throw from that block. A value of 0 or less
3462 indicates that this insn cannot throw. */
3463 note = find_reg_note (insn, REG_EH_REGION, NULL_RTX);
3466 int b = INTVAL (XEXP (note, 0));
3470 index = info->region_index[b];
3474 /* If we reach this point, and index is 0, there is no throw. */
3478 *handlers = info->handlers[index];
3479 return info->num_handlers[index];
3483 /* This function will free all memory associated with the eh_nesting info. */
3486 free_eh_nesting_info (info)
3487 eh_nesting_info *info;
3492 if (info->region_index)
3493 free (info->region_index);
3494 if (info->num_handlers)
3495 free (info->num_handlers);
3496 if (info->outer_index)
3497 free (info->outer_index);
3500 for (x = 0; x < info->region_count; x++)
3501 if (info->handlers[x])
3502 free (info->handlers[x]);
3503 free (info->handlers);