1 /* Implements exception handling.
2 Copyright (C) 1989, 1992-1999 Free Software Foundation, Inc.
3 Contributed by Mike Stump <mrs@cygnus.com>.
5 This file is part of GNU CC.
7 GNU CC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GNU CC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GNU CC; see the file COPYING. If not, write to
19 the Free Software Foundation, 59 Temple Place - Suite 330,
20 Boston, MA 02111-1307, USA. */
23 /* An exception is an event that can be signaled from within a
24 function. This event can then be "caught" or "trapped" by the
25 callers of this function. This potentially allows program flow to
26 be transferred to any arbitrary code associated with a function call
27 several levels up the stack.
29 The intended use for this mechanism is for signaling "exceptional
30 events" in an out-of-band fashion, hence its name. The C++ language
31 (and many other OO-styled or functional languages) practically
32 requires such a mechanism, as otherwise it becomes very difficult
33 or even impossible to signal failure conditions in complex
34 situations. The traditional C++ example is when an error occurs in
35 the process of constructing an object; without such a mechanism, it
36 is impossible to signal that the error occurs without adding global
37 state variables and error checks around every object construction.
39 The act of causing this event to occur is referred to as "throwing
40 an exception". (Alternate terms include "raising an exception" or
41 "signaling an exception".) The term "throw" is used because control
42 is returned to the callers of the function that is signaling the
43 exception, and thus there is the concept of "throwing" the
44 exception up the call stack.
46 There are two major codegen options for exception handling. The
47 flag -fsjlj-exceptions can be used to select the setjmp/longjmp
48 approach, which is the default. -fno-sjlj-exceptions can be used to
49 get the PC range table approach. While this is a compile time
50 flag, an entire application must be compiled with the same codegen
51 option. The first is a PC range table approach, the second is a
52 setjmp/longjmp based scheme. We will first discuss the PC range
53 table approach, after that, we will discuss the setjmp/longjmp
56 It is appropriate to speak of the "context of a throw". This
57 context refers to the address where the exception is thrown from,
58 and is used to determine which exception region will handle the
61 Regions of code within a function can be marked such that if it
62 contains the context of a throw, control will be passed to a
63 designated "exception handler". These areas are known as "exception
64 regions". Exception regions cannot overlap, but they can be nested
65 to any arbitrary depth. Also, exception regions cannot cross
68 Exception handlers can either be specified by the user (which we
69 will call a "user-defined handler") or generated by the compiler
70 (which we will designate as a "cleanup"). Cleanups are used to
71 perform tasks such as destruction of objects allocated on the
74 In the current implementation, cleanups are handled by allocating an
75 exception region for the area that the cleanup is designated for,
76 and the handler for the region performs the cleanup and then
77 rethrows the exception to the outer exception region. From the
78 standpoint of the current implementation, there is little
79 distinction made between a cleanup and a user-defined handler, and
80 the phrase "exception handler" can be used to refer to either one
81 equally well. (The section "Future Directions" below discusses how
84 Each object file that is compiled with exception handling contains
85 a static array of exception handlers named __EXCEPTION_TABLE__.
86 Each entry contains the starting and ending addresses of the
87 exception region, and the address of the handler designated for
90 If the target does not use the DWARF 2 frame unwind information, at
91 program startup each object file invokes a function named
92 __register_exceptions with the address of its local
93 __EXCEPTION_TABLE__. __register_exceptions is defined in libgcc2.c, and
94 is responsible for recording all of the exception regions into one list
95 (which is kept in a static variable named exception_table_list).
97 On targets that support crtstuff.c, the unwind information
98 is stored in a section named .eh_frame and the information for the
99 entire shared object or program is registered with a call to
100 __register_frame_info. On other targets, the information for each
101 translation unit is registered from the file generated by collect2.
102 __register_frame_info is defined in frame.c, and is responsible for
103 recording all of the unwind regions into one list (which is kept in a
104 static variable named unwind_table_list).
106 The function __throw is actually responsible for doing the
107 throw. On machines that have unwind info support, __throw is generated
108 by code in libgcc2.c, otherwise __throw is generated on a
109 per-object-file basis for each source file compiled with
110 -fexceptions by the C++ frontend. Before __throw is invoked,
111 the current context of the throw needs to be placed in the global
114 __throw attempts to find the appropriate exception handler for the
115 PC value stored in __eh_pc by calling __find_first_exception_table_match
116 (which is defined in libgcc2.c). If __find_first_exception_table_match
117 finds a relevant handler, __throw transfers control directly to it.
119 If a handler for the context being thrown from can't be found, __throw
120 walks (see Walking the stack below) the stack up the dynamic call chain to
121 continue searching for an appropriate exception handler based upon the
122 caller of the function it last sought a exception handler for. It stops
123 then either an exception handler is found, or when the top of the
124 call chain is reached.
126 If no handler is found, an external library function named
127 __terminate is called. If a handler is found, then we restart
128 our search for a handler at the end of the call chain, and repeat
129 the search process, but instead of just walking up the call chain,
130 we unwind the call chain as we walk up it.
132 Internal implementation details:
134 To associate a user-defined handler with a block of statements, the
135 function expand_start_try_stmts is used to mark the start of the
136 block of statements with which the handler is to be associated
137 (which is known as a "try block"). All statements that appear
138 afterwards will be associated with the try block.
140 A call to expand_start_all_catch marks the end of the try block,
141 and also marks the start of the "catch block" (the user-defined
142 handler) associated with the try block.
144 This user-defined handler will be invoked for *every* exception
145 thrown with the context of the try block. It is up to the handler
146 to decide whether or not it wishes to handle any given exception,
147 as there is currently no mechanism in this implementation for doing
148 this. (There are plans for conditionally processing an exception
149 based on its "type", which will provide a language-independent
152 If the handler chooses not to process the exception (perhaps by
153 looking at an "exception type" or some other additional data
154 supplied with the exception), it can fall through to the end of the
155 handler. expand_end_all_catch and expand_leftover_cleanups
156 add additional code to the end of each handler to take care of
157 rethrowing to the outer exception handler.
159 The handler also has the option to continue with "normal flow of
160 code", or in other words to resume executing at the statement
161 immediately after the end of the exception region. The variable
162 caught_return_label_stack contains a stack of labels, and jumping
163 to the topmost entry's label via expand_goto will resume normal
164 flow to the statement immediately after the end of the exception
165 region. If the handler falls through to the end, the exception will
166 be rethrown to the outer exception region.
168 The instructions for the catch block are kept as a separate
169 sequence, and will be emitted at the end of the function along with
170 the handlers specified via expand_eh_region_end. The end of the
171 catch block is marked with expand_end_all_catch.
173 Any data associated with the exception must currently be handled by
174 some external mechanism maintained in the frontend. For example,
175 the C++ exception mechanism passes an arbitrary value along with
176 the exception, and this is handled in the C++ frontend by using a
177 global variable to hold the value. (This will be changing in the
180 The mechanism in C++ for handling data associated with the
181 exception is clearly not thread-safe. For a thread-based
182 environment, another mechanism must be used (possibly using a
183 per-thread allocation mechanism if the size of the area that needs
184 to be allocated isn't known at compile time.)
186 Internally-generated exception regions (cleanups) are marked by
187 calling expand_eh_region_start to mark the start of the region,
188 and expand_eh_region_end (handler) is used to both designate the
189 end of the region and to associate a specified handler/cleanup with
190 the region. The rtl code in HANDLER will be invoked whenever an
191 exception occurs in the region between the calls to
192 expand_eh_region_start and expand_eh_region_end. After HANDLER is
193 executed, additional code is emitted to handle rethrowing the
194 exception to the outer exception handler. The code for HANDLER will
195 be emitted at the end of the function.
197 TARGET_EXPRs can also be used to designate exception regions. A
198 TARGET_EXPR gives an unwind-protect style interface commonly used
199 in functional languages such as LISP. The associated expression is
200 evaluated, and whether or not it (or any of the functions that it
201 calls) throws an exception, the protect expression is always
202 invoked. This implementation takes care of the details of
203 associating an exception table entry with the expression and
204 generating the necessary code (it actually emits the protect
205 expression twice, once for normal flow and once for the exception
206 case). As for the other handlers, the code for the exception case
207 will be emitted at the end of the function.
209 Cleanups can also be specified by using add_partial_entry (handler)
210 and end_protect_partials. add_partial_entry creates the start of
211 a new exception region; HANDLER will be invoked if an exception is
212 thrown with the context of the region between the calls to
213 add_partial_entry and end_protect_partials. end_protect_partials is
214 used to mark the end of these regions. add_partial_entry can be
215 called as many times as needed before calling end_protect_partials.
216 However, end_protect_partials should only be invoked once for each
217 group of calls to add_partial_entry as the entries are queued
218 and all of the outstanding entries are processed simultaneously
219 when end_protect_partials is invoked. Similarly to the other
220 handlers, the code for HANDLER will be emitted at the end of the
223 The generated RTL for an exception region includes
224 NOTE_INSN_EH_REGION_BEG and NOTE_INSN_EH_REGION_END notes that mark
225 the start and end of the exception region. A unique label is also
226 generated at the start of the exception region, which is available
227 by looking at the ehstack variable. The topmost entry corresponds
228 to the current region.
230 In the current implementation, an exception can only be thrown from
231 a function call (since the mechanism used to actually throw an
232 exception involves calling __throw). If an exception region is
233 created but no function calls occur within that region, the region
234 can be safely optimized away (along with its exception handlers)
235 since no exceptions can ever be caught in that region. This
236 optimization is performed unless -fasynchronous-exceptions is
237 given. If the user wishes to throw from a signal handler, or other
238 asynchronous place, -fasynchronous-exceptions should be used when
239 compiling for maximally correct code, at the cost of additional
240 exception regions. Using -fasynchronous-exceptions only produces
241 code that is reasonably safe in such situations, but a correct
242 program cannot rely upon this working. It can be used in failsafe
243 code, where trying to continue on, and proceeding with potentially
244 incorrect results is better than halting the program.
249 The stack is walked by starting with a pointer to the current
250 frame, and finding the pointer to the callers frame. The unwind info
251 tells __throw how to find it.
255 When we use the term unwinding the stack, we mean undoing the
256 effects of the function prologue in a controlled fashion so that we
257 still have the flow of control. Otherwise, we could just return
258 (jump to the normal end of function epilogue).
260 This is done in __throw in libgcc2.c when we know that a handler exists
261 in a frame higher up the call stack than its immediate caller.
263 To unwind, we find the unwind data associated with the frame, if any.
264 If we don't find any, we call the library routine __terminate. If we do
265 find it, we use the information to copy the saved register values from
266 that frame into the register save area in the frame for __throw, return
267 into a stub which updates the stack pointer, and jump to the handler.
268 The normal function epilogue for __throw handles restoring the saved
269 values into registers.
271 When unwinding, we use this method if we know it will
272 work (if DWARF2_UNWIND_INFO is defined). Otherwise, we know that
273 an inline unwinder will have been emitted for any function that
274 __unwind_function cannot unwind. The inline unwinder appears as a
275 normal exception handler for the entire function, for any function
276 that we know cannot be unwound by __unwind_function. We inform the
277 compiler of whether a function can be unwound with
278 __unwind_function by having DOESNT_NEED_UNWINDER evaluate to true
279 when the unwinder isn't needed. __unwind_function is used as an
280 action of last resort. If no other method can be used for
281 unwinding, __unwind_function is used. If it cannot unwind, it
282 should call __terminate.
284 By default, if the target-specific backend doesn't supply a definition
285 for __unwind_function and doesn't support DWARF2_UNWIND_INFO, inlined
286 unwinders will be used instead. The main tradeoff here is in text space
287 utilization. Obviously, if inline unwinders have to be generated
288 repeatedly, this uses much more space than if a single routine is used.
290 However, it is simply not possible on some platforms to write a
291 generalized routine for doing stack unwinding without having some
292 form of additional data associated with each function. The current
293 implementation can encode this data in the form of additional
294 machine instructions or as static data in tabular form. The later
295 is called the unwind data.
297 The backend macro DOESNT_NEED_UNWINDER is used to conditionalize whether
298 or not per-function unwinders are needed. If DOESNT_NEED_UNWINDER is
299 defined and has a non-zero value, a per-function unwinder is not emitted
300 for the current function. If the static unwind data is supported, then
301 a per-function unwinder is not emitted.
303 On some platforms it is possible that neither __unwind_function
304 nor inlined unwinders are available. For these platforms it is not
305 possible to throw through a function call, and abort will be
306 invoked instead of performing the throw.
308 The reason the unwind data may be needed is that on some platforms
309 the order and types of data stored on the stack can vary depending
310 on the type of function, its arguments and returned values, and the
311 compilation options used (optimization versus non-optimization,
312 -fomit-frame-pointer, processor variations, etc).
314 Unfortunately, this also means that throwing through functions that
315 aren't compiled with exception handling support will still not be
316 possible on some platforms. This problem is currently being
317 investigated, but no solutions have been found that do not imply
318 some unacceptable performance penalties.
322 Currently __throw makes no differentiation between cleanups and
323 user-defined exception regions. While this makes the implementation
324 simple, it also implies that it is impossible to determine if a
325 user-defined exception handler exists for a given exception without
326 completely unwinding the stack in the process. This is undesirable
327 from the standpoint of debugging, as ideally it would be possible
328 to trap unhandled exceptions in the debugger before the process of
329 unwinding has even started.
331 This problem can be solved by marking user-defined handlers in a
332 special way (probably by adding additional bits to exception_table_list).
333 A two-pass scheme could then be used by __throw to iterate
334 through the table. The first pass would search for a relevant
335 user-defined handler for the current context of the throw, and if
336 one is found, the second pass would then invoke all needed cleanups
337 before jumping to the user-defined handler.
339 Many languages (including C++ and Ada) make execution of a
340 user-defined handler conditional on the "type" of the exception
341 thrown. (The type of the exception is actually the type of the data
342 that is thrown with the exception.) It will thus be necessary for
343 __throw to be able to determine if a given user-defined
344 exception handler will actually be executed, given the type of
347 One scheme is to add additional information to exception_table_list
348 as to the types of exceptions accepted by each handler. __throw
349 can do the type comparisons and then determine if the handler is
350 actually going to be executed.
352 There is currently no significant level of debugging support
353 available, other than to place a breakpoint on __throw. While
354 this is sufficient in most cases, it would be helpful to be able to
355 know where a given exception was going to be thrown to before it is
356 actually thrown, and to be able to choose between stopping before
357 every exception region (including cleanups), or just user-defined
358 exception regions. This should be possible to do in the two-pass
359 scheme by adding additional labels to __throw for appropriate
360 breakpoints, and additional debugger commands could be added to
361 query various state variables to determine what actions are to be
364 Another major problem that is being worked on is the issue with stack
365 unwinding on various platforms. Currently the only platforms that have
366 support for the generation of a generic unwinder are the SPARC and MIPS.
367 All other ports require per-function unwinders, which produce large
368 amounts of code bloat.
370 For setjmp/longjmp based exception handling, some of the details
371 are as above, but there are some additional details. This section
372 discusses the details.
374 We don't use NOTE_INSN_EH_REGION_{BEG,END} pairs. We don't
375 optimize EH regions yet. We don't have to worry about machine
376 specific issues with unwinding the stack, as we rely upon longjmp
377 for all the machine specific details. There is no variable context
378 of a throw, just the one implied by the dynamic handler stack
379 pointed to by the dynamic handler chain. There is no exception
380 table, and no calls to __register_exceptions. __sjthrow is used
381 instead of __throw, and it works by using the dynamic handler
382 chain, and longjmp. -fasynchronous-exceptions has no effect, as
383 the elimination of trivial exception regions is not yet performed.
385 A frontend can set protect_cleanup_actions_with_terminate when all
386 the cleanup actions should be protected with an EH region that
387 calls terminate when an unhandled exception is throw. C++ does
388 this, Ada does not. */
392 #include "defaults.h"
393 #include "eh-common.h"
399 #include "function.h"
400 #include "insn-flags.h"
402 #include "insn-codes.h"
404 #include "hard-reg-set.h"
405 #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 PROTO((struct eh_stack *));
455 static struct eh_entry * pop_eh_entry PROTO((struct eh_stack *));
456 static void enqueue_eh_entry PROTO((struct eh_queue *, struct eh_entry *));
457 static struct eh_entry * dequeue_eh_entry PROTO((struct eh_queue *));
458 static rtx call_get_eh_context PROTO((void));
459 static void start_dynamic_cleanup PROTO((tree, tree));
460 static void start_dynamic_handler PROTO((void));
461 static void expand_rethrow PROTO((rtx));
462 static void output_exception_table_entry PROTO((FILE *, int));
463 static int can_throw PROTO((rtx));
464 static rtx scan_region PROTO((rtx, int, int *));
465 static void eh_regs PROTO((rtx *, rtx *, rtx *, int));
466 static void set_insn_eh_region PROTO((rtx *, int));
467 #ifdef DONT_USE_BUILTIN_SETJMP
468 static void jumpif_rtx PROTO((rtx, rtx));
471 rtx expand_builtin_return_addr PROTO((enum built_in_function, int, rtx));
473 /* Various support routines to manipulate the various data structures
474 used by the exception handling code. */
476 extern struct obstack permanent_obstack;
478 /* Generate a SYMBOL_REF for rethrow to use */
480 create_rethrow_ref (region_num)
487 push_obstacks_nochange ();
488 end_temporary_allocation ();
490 ASM_GENERATE_INTERNAL_LABEL (buf, "LRTH", region_num);
491 ptr = (char *) obstack_copy0 (&permanent_obstack, buf, strlen (buf));
492 def = gen_rtx_SYMBOL_REF (Pmode, ptr);
493 SYMBOL_REF_NEED_ADJUST (def) = 1;
499 /* Push a label entry onto the given STACK. */
502 push_label_entry (stack, rlabel, tlabel)
503 struct label_node **stack;
507 struct label_node *newnode
508 = (struct label_node *) xmalloc (sizeof (struct label_node));
511 newnode->u.rlabel = rlabel;
513 newnode->u.tlabel = tlabel;
514 newnode->chain = *stack;
518 /* Pop a label entry from the given STACK. */
521 pop_label_entry (stack)
522 struct label_node **stack;
525 struct label_node *tempnode;
531 label = tempnode->u.rlabel;
532 *stack = (*stack)->chain;
538 /* Return the top element of the given STACK. */
541 top_label_entry (stack)
542 struct label_node **stack;
547 return (*stack)->u.tlabel;
550 /* get an exception label. These must be on the permanent obstack */
553 gen_exception_label ()
556 lab = gen_label_rtx ();
560 /* Push a new eh_node entry onto STACK. */
563 push_eh_entry (stack)
564 struct eh_stack *stack;
566 struct eh_node *node = (struct eh_node *) xmalloc (sizeof (struct eh_node));
567 struct eh_entry *entry = (struct eh_entry *) xmalloc (sizeof (struct eh_entry));
569 rtx rlab = gen_exception_label ();
570 entry->finalization = NULL_TREE;
571 entry->label_used = 0;
572 entry->exception_handler_label = rlab;
573 entry->false_label = NULL_RTX;
574 if (! flag_new_exceptions)
575 entry->outer_context = gen_label_rtx ();
577 entry->outer_context = create_rethrow_ref (CODE_LABEL_NUMBER (rlab));
578 entry->rethrow_label = entry->outer_context;
581 node->chain = stack->top;
585 /* push an existing entry onto a stack. */
587 push_entry (stack, entry)
588 struct eh_stack *stack;
589 struct eh_entry *entry;
591 struct eh_node *node = (struct eh_node *) xmalloc (sizeof (struct eh_node));
593 node->chain = stack->top;
597 /* Pop an entry from the given STACK. */
599 static struct eh_entry *
601 struct eh_stack *stack;
603 struct eh_node *tempnode;
604 struct eh_entry *tempentry;
606 tempnode = stack->top;
607 tempentry = tempnode->entry;
608 stack->top = stack->top->chain;
614 /* Enqueue an ENTRY onto the given QUEUE. */
617 enqueue_eh_entry (queue, entry)
618 struct eh_queue *queue;
619 struct eh_entry *entry;
621 struct eh_node *node = (struct eh_node *) xmalloc (sizeof (struct eh_node));
626 if (queue->head == NULL)
632 queue->tail->chain = node;
637 /* Dequeue an entry from the given QUEUE. */
639 static struct eh_entry *
640 dequeue_eh_entry (queue)
641 struct eh_queue *queue;
643 struct eh_node *tempnode;
644 struct eh_entry *tempentry;
646 if (queue->head == NULL)
649 tempnode = queue->head;
650 queue->head = queue->head->chain;
652 tempentry = tempnode->entry;
659 receive_exception_label (handler_label)
662 emit_label (handler_label);
664 #ifdef HAVE_exception_receiver
665 if (! exceptions_via_longjmp)
666 if (HAVE_exception_receiver)
667 emit_insn (gen_exception_receiver ());
670 #ifdef HAVE_nonlocal_goto_receiver
671 if (! exceptions_via_longjmp)
672 if (HAVE_nonlocal_goto_receiver)
673 emit_insn (gen_nonlocal_goto_receiver ());
680 int range_number; /* EH region number from EH NOTE insn's. */
681 rtx rethrow_label; /* Label for rethrow. */
682 int rethrow_ref; /* Is rethrow referenced? */
683 struct handler_info *handlers;
687 /* table of function eh regions */
688 static struct func_eh_entry *function_eh_regions = NULL;
689 static int num_func_eh_entries = 0;
690 static int current_func_eh_entry = 0;
692 #define SIZE_FUNC_EH(X) (sizeof (struct func_eh_entry) * X)
694 /* Add a new eh_entry for this function, and base it off of the information
695 in the EH_ENTRY parameter. A NULL parameter is invalid.
696 OUTER_CONTEXT is a label which is used for rethrowing. The number
697 returned is an number which uniquely identifies this exception range. */
700 new_eh_region_entry (note_eh_region, rethrow)
704 if (current_func_eh_entry == num_func_eh_entries)
706 if (num_func_eh_entries == 0)
708 function_eh_regions =
709 (struct func_eh_entry *) malloc (SIZE_FUNC_EH (50));
710 num_func_eh_entries = 50;
714 num_func_eh_entries = num_func_eh_entries * 3 / 2;
715 function_eh_regions = (struct func_eh_entry *)
716 realloc (function_eh_regions, SIZE_FUNC_EH (num_func_eh_entries));
719 function_eh_regions[current_func_eh_entry].range_number = note_eh_region;
720 if (rethrow == NULL_RTX)
721 function_eh_regions[current_func_eh_entry].rethrow_label =
722 create_rethrow_ref (note_eh_region);
724 function_eh_regions[current_func_eh_entry].rethrow_label = rethrow;
725 function_eh_regions[current_func_eh_entry].handlers = NULL;
727 return current_func_eh_entry++;
730 /* Add new handler information to an exception range. The first parameter
731 specifies the range number (returned from new_eh_entry()). The second
732 parameter specifies the handler. By default the handler is inserted at
733 the end of the list. A handler list may contain only ONE NULL_TREE
734 typeinfo entry. Regardless where it is positioned, a NULL_TREE entry
735 is always output as the LAST handler in the exception table for a region. */
738 add_new_handler (region, newhandler)
740 struct handler_info *newhandler;
742 struct handler_info *last;
744 newhandler->next = NULL;
745 last = function_eh_regions[region].handlers;
747 function_eh_regions[region].handlers = newhandler;
750 for ( ; ; last = last->next)
752 if (last->type_info == CATCH_ALL_TYPE)
753 pedwarn ("additional handler after ...");
754 if (last->next == NULL)
757 last->next = newhandler;
761 /* Remove a handler label. The handler label is being deleted, so all
762 regions which reference this handler should have it removed from their
763 list of possible handlers. Any region which has the final handler
764 removed can be deleted. */
766 void remove_handler (removing_label)
769 struct handler_info *handler, *last;
771 for (x = 0 ; x < current_func_eh_entry; ++x)
774 handler = function_eh_regions[x].handlers;
775 for ( ; handler; last = handler, handler = handler->next)
776 if (handler->handler_label == removing_label)
780 last->next = handler->next;
784 function_eh_regions[x].handlers = handler->next;
789 /* This function will return a malloc'd pointer to an array of
790 void pointer representing the runtime match values that
791 currently exist in all regions. */
794 find_all_handler_type_matches (array)
797 struct handler_info *handler, *last;
806 if (!doing_eh (0) || ! flag_new_exceptions)
810 ptr = (void **)malloc (max_ptr * sizeof (void *));
815 for (x = 0 ; x < current_func_eh_entry; x++)
818 handler = function_eh_regions[x].handlers;
819 for ( ; handler; last = handler, handler = handler->next)
821 val = handler->type_info;
822 if (val != NULL && val != CATCH_ALL_TYPE)
824 /* See if this match value has already been found. */
825 for (y = 0; y < n_ptr; y++)
829 /* If we break early, we already found this value. */
833 /* Do we need to allocate more space? */
834 if (n_ptr >= max_ptr)
836 max_ptr += max_ptr / 2;
837 ptr = (void **)realloc (ptr, max_ptr * sizeof (void *));
850 /* Create a new handler structure initialized with the handler label and
851 typeinfo fields passed in. */
853 struct handler_info *
854 get_new_handler (handler, typeinfo)
858 struct handler_info* ptr;
859 ptr = (struct handler_info *) malloc (sizeof (struct handler_info));
860 ptr->handler_label = handler;
861 ptr->handler_number = CODE_LABEL_NUMBER (handler);
862 ptr->type_info = typeinfo;
870 /* Find the index in function_eh_regions associated with a NOTE region. If
871 the region cannot be found, a -1 is returned. This should never happen! */
874 find_func_region (insn_region)
878 for (x = 0; x < current_func_eh_entry; x++)
879 if (function_eh_regions[x].range_number == insn_region)
885 /* Get a pointer to the first handler in an exception region's list. */
887 struct handler_info *
888 get_first_handler (region)
891 return function_eh_regions[find_func_region (region)].handlers;
894 /* Clean out the function_eh_region table and free all memory */
897 clear_function_eh_region ()
900 struct handler_info *ptr, *next;
901 for (x = 0; x < current_func_eh_entry; x++)
902 for (ptr = function_eh_regions[x].handlers; ptr != NULL; ptr = next)
907 free (function_eh_regions);
908 num_func_eh_entries = 0;
909 current_func_eh_entry = 0;
912 /* Make a duplicate of an exception region by copying all the handlers
913 for an exception region. Return the new handler index. The final
914 parameter is a routine which maps old labels to new ones. */
917 duplicate_eh_handlers (old_note_eh_region, new_note_eh_region, map)
918 int old_note_eh_region, new_note_eh_region;
919 rtx (*map) PARAMS ((rtx));
921 struct handler_info *ptr, *new_ptr;
922 int new_region, region;
924 region = find_func_region (old_note_eh_region);
926 fatal ("Cannot duplicate non-existant exception region.");
928 /* duplicate_eh_handlers may have been called during a symbol remap. */
929 new_region = find_func_region (new_note_eh_region);
930 if (new_region != -1)
933 new_region = new_eh_region_entry (new_note_eh_region, NULL_RTX);
935 ptr = function_eh_regions[region].handlers;
937 for ( ; ptr; ptr = ptr->next)
939 new_ptr = get_new_handler (map (ptr->handler_label), ptr->type_info);
940 add_new_handler (new_region, new_ptr);
947 /* Given a rethrow symbol, find the EH region number this is for. */
949 eh_region_from_symbol (sym)
953 if (sym == last_rethrow_symbol)
955 for (x = 0; x < current_func_eh_entry; x++)
956 if (function_eh_regions[x].rethrow_label == sym)
957 return function_eh_regions[x].range_number;
962 /* When inlining/unrolling, we have to map the symbols passed to
963 __rethrow as well. This performs the remap. If a symbol isn't foiund,
964 the original one is returned. This is not an efficient routine,
965 so don't call it on everything!! */
967 rethrow_symbol_map (sym, map)
969 rtx (*map) PARAMS ((rtx));
972 for (x = 0; x < current_func_eh_entry; x++)
973 if (function_eh_regions[x].rethrow_label == sym)
975 /* We've found the original region, now lets determine which region
977 rtx l1 = function_eh_regions[x].handlers->handler_label;
979 y = CODE_LABEL_NUMBER (l2); /* This is the new region number */
980 x = find_func_region (y); /* Get the new permanent region */
981 if (x == -1) /* Hmm, Doesn't exist yet */
983 x = duplicate_eh_handlers (CODE_LABEL_NUMBER (l1), y, map);
984 /* Since we're mapping it, it must be used. */
985 function_eh_regions[x].rethrow_ref = 1;
987 return function_eh_regions[x].rethrow_label;
993 rethrow_used (region)
996 if (flag_new_exceptions)
998 int ret = function_eh_regions[find_func_region (region)].rethrow_ref;
1005 /* Routine to see if exception handling is turned on.
1006 DO_WARN is non-zero if we want to inform the user that exception
1007 handling is turned off.
1009 This is used to ensure that -fexceptions has been specified if the
1010 compiler tries to use any exception-specific functions. */
1016 if (! flag_exceptions)
1018 static int warned = 0;
1019 if (! warned && do_warn)
1021 error ("exception handling disabled, use -fexceptions to enable");
1029 /* Given a return address in ADDR, determine the address we should use
1030 to find the corresponding EH region. */
1033 eh_outer_context (addr)
1036 /* First mask out any unwanted bits. */
1037 #ifdef MASK_RETURN_ADDR
1038 expand_and (addr, MASK_RETURN_ADDR, addr);
1041 /* Then adjust to find the real return address. */
1042 #if defined (RETURN_ADDR_OFFSET)
1043 addr = plus_constant (addr, RETURN_ADDR_OFFSET);
1049 /* Start a new exception region for a region of code that has a
1050 cleanup action and push the HANDLER for the region onto
1051 protect_list. All of the regions created with add_partial_entry
1052 will be ended when end_protect_partials is invoked. */
1055 add_partial_entry (handler)
1058 expand_eh_region_start ();
1060 /* Make sure the entry is on the correct obstack. */
1061 push_obstacks_nochange ();
1062 resume_temporary_allocation ();
1064 /* Because this is a cleanup action, we may have to protect the handler
1065 with __terminate. */
1066 handler = protect_with_terminate (handler);
1068 protect_list = tree_cons (NULL_TREE, handler, protect_list);
1072 /* Emit code to get EH context to current function. */
1075 call_get_eh_context ()
1080 if (fn == NULL_TREE)
1083 fn = get_identifier ("__get_eh_context");
1084 push_obstacks_nochange ();
1085 end_temporary_allocation ();
1086 fntype = build_pointer_type (build_pointer_type
1087 (build_pointer_type (void_type_node)));
1088 fntype = build_function_type (fntype, NULL_TREE);
1089 fn = build_decl (FUNCTION_DECL, fn, fntype);
1090 DECL_EXTERNAL (fn) = 1;
1091 TREE_PUBLIC (fn) = 1;
1092 DECL_ARTIFICIAL (fn) = 1;
1093 TREE_READONLY (fn) = 1;
1094 make_decl_rtl (fn, NULL_PTR, 1);
1095 assemble_external (fn);
1099 expr = build1 (ADDR_EXPR, build_pointer_type (TREE_TYPE (fn)), fn);
1100 expr = build (CALL_EXPR, TREE_TYPE (TREE_TYPE (fn)),
1101 expr, NULL_TREE, NULL_TREE);
1102 TREE_SIDE_EFFECTS (expr) = 1;
1104 return copy_to_reg (expand_expr (expr, NULL_RTX, VOIDmode, 0));
1107 /* Get a reference to the EH context.
1108 We will only generate a register for the current function EH context here,
1109 and emit a USE insn to mark that this is a EH context register.
1111 Later, emit_eh_context will emit needed call to __get_eh_context
1112 in libgcc2, and copy the value to the register we have generated. */
1117 if (current_function_ehc == 0)
1121 current_function_ehc = gen_reg_rtx (Pmode);
1123 insn = gen_rtx_USE (GET_MODE (current_function_ehc),
1124 current_function_ehc);
1125 insn = emit_insn_before (insn, get_first_nonparm_insn ());
1128 = gen_rtx_EXPR_LIST (REG_EH_CONTEXT, current_function_ehc,
1131 return current_function_ehc;
1134 /* Get a reference to the dynamic handler chain. It points to the
1135 pointer to the next element in the dynamic handler chain. It ends
1136 when there are no more elements in the dynamic handler chain, when
1137 the value is &top_elt from libgcc2.c. Immediately after the
1138 pointer, is an area suitable for setjmp/longjmp when
1139 DONT_USE_BUILTIN_SETJMP is defined, and an area suitable for
1140 __builtin_setjmp/__builtin_longjmp when DONT_USE_BUILTIN_SETJMP
1144 get_dynamic_handler_chain ()
1146 rtx ehc, dhc, result;
1148 ehc = get_eh_context ();
1150 /* This is the offset of dynamic_handler_chain in the eh_context struct
1151 declared in eh-common.h. If its location is change, change this offset */
1152 dhc = plus_constant (ehc, POINTER_SIZE / BITS_PER_UNIT);
1154 result = copy_to_reg (dhc);
1156 /* We don't want a copy of the dcc, but rather, the single dcc. */
1157 return gen_rtx_MEM (Pmode, result);
1160 /* Get a reference to the dynamic cleanup chain. It points to the
1161 pointer to the next element in the dynamic cleanup chain.
1162 Immediately after the pointer, are two Pmode variables, one for a
1163 pointer to a function that performs the cleanup action, and the
1164 second, the argument to pass to that function. */
1167 get_dynamic_cleanup_chain ()
1169 rtx dhc, dcc, result;
1171 dhc = get_dynamic_handler_chain ();
1172 dcc = plus_constant (dhc, POINTER_SIZE / BITS_PER_UNIT);
1174 result = copy_to_reg (dcc);
1176 /* We don't want a copy of the dcc, but rather, the single dcc. */
1177 return gen_rtx_MEM (Pmode, result);
1180 #ifdef DONT_USE_BUILTIN_SETJMP
1181 /* Generate code to evaluate X and jump to LABEL if the value is nonzero.
1182 LABEL is an rtx of code CODE_LABEL, in this function. */
1185 jumpif_rtx (x, label)
1189 jumpif (make_tree (type_for_mode (GET_MODE (x), 0), x), label);
1193 /* Start a dynamic cleanup on the EH runtime dynamic cleanup stack.
1194 We just need to create an element for the cleanup list, and push it
1197 A dynamic cleanup is a cleanup action implied by the presence of an
1198 element on the EH runtime dynamic cleanup stack that is to be
1199 performed when an exception is thrown. The cleanup action is
1200 performed by __sjthrow when an exception is thrown. Only certain
1201 actions can be optimized into dynamic cleanup actions. For the
1202 restrictions on what actions can be performed using this routine,
1203 see expand_eh_region_start_tree. */
1206 start_dynamic_cleanup (func, arg)
1211 rtx new_func, new_arg;
1215 /* We allocate enough room for a pointer to the function, and
1219 /* XXX, FIXME: The stack space allocated this way is too long lived,
1220 but there is no allocation routine that allocates at the level of
1221 the last binding contour. */
1222 buf = assign_stack_local (BLKmode,
1223 GET_MODE_SIZE (Pmode)*(size+1),
1226 buf = change_address (buf, Pmode, NULL_RTX);
1228 /* Store dcc into the first word of the newly allocated buffer. */
1230 dcc = get_dynamic_cleanup_chain ();
1231 emit_move_insn (buf, dcc);
1233 /* Store func and arg into the cleanup list element. */
1235 new_func = gen_rtx_MEM (Pmode, plus_constant (XEXP (buf, 0),
1236 GET_MODE_SIZE (Pmode)));
1237 new_arg = gen_rtx_MEM (Pmode, plus_constant (XEXP (buf, 0),
1238 GET_MODE_SIZE (Pmode)*2));
1239 x = expand_expr (func, new_func, Pmode, 0);
1241 emit_move_insn (new_func, x);
1243 x = expand_expr (arg, new_arg, Pmode, 0);
1245 emit_move_insn (new_arg, x);
1247 /* Update the cleanup chain. */
1249 x = force_operand (XEXP (buf, 0), dcc);
1251 emit_move_insn (dcc, x);
1254 /* Emit RTL to start a dynamic handler on the EH runtime dynamic
1255 handler stack. This should only be used by expand_eh_region_start
1256 or expand_eh_region_start_tree. */
1259 start_dynamic_handler ()
1265 #ifndef DONT_USE_BUILTIN_SETJMP
1266 /* The number of Pmode words for the setjmp buffer, when using the
1267 builtin setjmp/longjmp, see expand_builtin, case
1268 BUILT_IN_LONGJMP. */
1272 size = JMP_BUF_SIZE;
1274 /* Should be large enough for most systems, if it is not,
1275 JMP_BUF_SIZE should be defined with the proper value. It will
1276 also tend to be larger than necessary for most systems, a more
1277 optimal port will define JMP_BUF_SIZE. */
1278 size = FIRST_PSEUDO_REGISTER+2;
1281 /* XXX, FIXME: The stack space allocated this way is too long lived,
1282 but there is no allocation routine that allocates at the level of
1283 the last binding contour. */
1284 arg = assign_stack_local (BLKmode,
1285 GET_MODE_SIZE (Pmode)*(size+1),
1288 arg = change_address (arg, Pmode, NULL_RTX);
1290 /* Store dhc into the first word of the newly allocated buffer. */
1292 dhc = get_dynamic_handler_chain ();
1293 dcc = gen_rtx_MEM (Pmode, plus_constant (XEXP (arg, 0),
1294 GET_MODE_SIZE (Pmode)));
1295 emit_move_insn (arg, dhc);
1297 /* Zero out the start of the cleanup chain. */
1298 emit_move_insn (dcc, const0_rtx);
1300 /* The jmpbuf starts two words into the area allocated. */
1301 buf = plus_constant (XEXP (arg, 0), GET_MODE_SIZE (Pmode)*2);
1303 #ifdef DONT_USE_BUILTIN_SETJMP
1304 x = emit_library_call_value (setjmp_libfunc, NULL_RTX, 1, SImode, 1,
1306 /* If we come back here for a catch, transfer control to the handler. */
1307 jumpif_rtx (x, ehstack.top->entry->exception_handler_label);
1310 /* A label to continue execution for the no exception case. */
1311 rtx noex = gen_label_rtx();
1312 x = expand_builtin_setjmp (buf, NULL_RTX, noex,
1313 ehstack.top->entry->exception_handler_label);
1318 /* We are committed to this, so update the handler chain. */
1320 emit_move_insn (dhc, force_operand (XEXP (arg, 0), NULL_RTX));
1323 /* Start an exception handling region for the given cleanup action.
1324 All instructions emitted after this point are considered to be part
1325 of the region until expand_eh_region_end is invoked. CLEANUP is
1326 the cleanup action to perform. The return value is true if the
1327 exception region was optimized away. If that case,
1328 expand_eh_region_end does not need to be called for this cleanup,
1331 This routine notices one particular common case in C++ code
1332 generation, and optimizes it so as to not need the exception
1333 region. It works by creating a dynamic cleanup action, instead of
1334 a using an exception region. */
1337 expand_eh_region_start_tree (decl, cleanup)
1341 /* This is the old code. */
1345 /* The optimization only applies to actions protected with
1346 terminate, and only applies if we are using the setjmp/longjmp
1348 if (exceptions_via_longjmp
1349 && protect_cleanup_actions_with_terminate)
1354 /* Ignore any UNSAVE_EXPR. */
1355 if (TREE_CODE (cleanup) == UNSAVE_EXPR)
1356 cleanup = TREE_OPERAND (cleanup, 0);
1358 /* Further, it only applies if the action is a call, if there
1359 are 2 arguments, and if the second argument is 2. */
1361 if (TREE_CODE (cleanup) == CALL_EXPR
1362 && (args = TREE_OPERAND (cleanup, 1))
1363 && (func = TREE_OPERAND (cleanup, 0))
1364 && (arg = TREE_VALUE (args))
1365 && (args = TREE_CHAIN (args))
1367 /* is the second argument 2? */
1368 && TREE_CODE (TREE_VALUE (args)) == INTEGER_CST
1369 && TREE_INT_CST_LOW (TREE_VALUE (args)) == 2
1370 && TREE_INT_CST_HIGH (TREE_VALUE (args)) == 0
1372 /* Make sure there are no other arguments. */
1373 && TREE_CHAIN (args) == NULL_TREE)
1375 /* Arrange for returns and gotos to pop the entry we make on the
1376 dynamic cleanup stack. */
1377 expand_dcc_cleanup (decl);
1378 start_dynamic_cleanup (func, arg);
1383 expand_eh_region_start_for_decl (decl);
1384 ehstack.top->entry->finalization = cleanup;
1389 /* Just like expand_eh_region_start, except if a cleanup action is
1390 entered on the cleanup chain, the TREE_PURPOSE of the element put
1391 on the chain is DECL. DECL should be the associated VAR_DECL, if
1392 any, otherwise it should be NULL_TREE. */
1395 expand_eh_region_start_for_decl (decl)
1400 /* This is the old code. */
1404 /* We need a new block to record the start and end of the
1405 dynamic handler chain. We also want to prevent jumping into
1407 expand_start_bindings (0);
1409 /* But we don't need or want a new temporary level. */
1412 /* Mark this block as created by expand_eh_region_start. This
1413 is so that we can pop the block with expand_end_bindings
1415 mark_block_as_eh_region ();
1417 if (exceptions_via_longjmp)
1419 /* Arrange for returns and gotos to pop the entry we make on the
1420 dynamic handler stack. */
1421 expand_dhc_cleanup (decl);
1424 push_eh_entry (&ehstack);
1425 note = emit_note (NULL_PTR, NOTE_INSN_EH_REGION_BEG);
1426 NOTE_BLOCK_NUMBER (note)
1427 = CODE_LABEL_NUMBER (ehstack.top->entry->exception_handler_label);
1428 if (exceptions_via_longjmp)
1429 start_dynamic_handler ();
1432 /* Start an exception handling region. All instructions emitted after
1433 this point are considered to be part of the region until
1434 expand_eh_region_end is invoked. */
1437 expand_eh_region_start ()
1439 expand_eh_region_start_for_decl (NULL_TREE);
1442 /* End an exception handling region. The information about the region
1443 is found on the top of ehstack.
1445 HANDLER is either the cleanup for the exception region, or if we're
1446 marking the end of a try block, HANDLER is integer_zero_node.
1448 HANDLER will be transformed to rtl when expand_leftover_cleanups
1452 expand_eh_region_end (handler)
1455 struct eh_entry *entry;
1462 entry = pop_eh_entry (&ehstack);
1464 note = emit_note (NULL_PTR, NOTE_INSN_EH_REGION_END);
1465 ret = NOTE_BLOCK_NUMBER (note)
1466 = CODE_LABEL_NUMBER (entry->exception_handler_label);
1467 if (exceptions_via_longjmp == 0 && ! flag_new_exceptions
1468 /* We share outer_context between regions; only emit it once. */
1469 && INSN_UID (entry->outer_context) == 0)
1473 label = gen_label_rtx ();
1476 /* Emit a label marking the end of this exception region that
1477 is used for rethrowing into the outer context. */
1478 emit_label (entry->outer_context);
1479 expand_internal_throw ();
1484 entry->finalization = handler;
1486 /* create region entry in final exception table */
1487 r = new_eh_region_entry (NOTE_BLOCK_NUMBER (note), entry->rethrow_label);
1489 enqueue_eh_entry (&ehqueue, entry);
1491 /* If we have already started ending the bindings, don't recurse. */
1492 if (is_eh_region ())
1494 /* Because we don't need or want a new temporary level and
1495 because we didn't create one in expand_eh_region_start,
1496 create a fake one now to avoid removing one in
1497 expand_end_bindings. */
1500 mark_block_as_not_eh_region ();
1502 expand_end_bindings (NULL_TREE, 0, 0);
1506 /* End the EH region for a goto fixup. We only need them in the region-based
1510 expand_fixup_region_start ()
1512 if (! doing_eh (0) || exceptions_via_longjmp)
1515 expand_eh_region_start ();
1518 /* End the EH region for a goto fixup. CLEANUP is the cleanup we just
1519 expanded; to avoid running it twice if it throws, we look through the
1520 ehqueue for a matching region and rethrow from its outer_context. */
1523 expand_fixup_region_end (cleanup)
1526 struct eh_node *node;
1529 if (! doing_eh (0) || exceptions_via_longjmp)
1532 for (node = ehstack.top; node && node->entry->finalization != cleanup; )
1535 for (node = ehqueue.head; node && node->entry->finalization != cleanup; )
1540 /* If the outer context label has not been issued yet, we don't want
1541 to issue it as a part of this region, unless this is the
1542 correct region for the outer context. If we did, then the label for
1543 the outer context will be WITHIN the begin/end labels,
1544 and we could get an infinte loop when it tried to rethrow, or just
1545 generally incorrect execution following a throw. */
1547 dont_issue = ((INSN_UID (node->entry->outer_context) == 0)
1548 && (ehstack.top->entry != node->entry));
1550 ehstack.top->entry->outer_context = node->entry->outer_context;
1552 /* Since we are rethrowing to the OUTER region, we know we don't need
1553 a jump around sequence for this region, so we'll pretend the outer
1554 context label has been issued by setting INSN_UID to 1, then clearing
1555 it again afterwards. */
1558 INSN_UID (node->entry->outer_context) = 1;
1560 /* Just rethrow. size_zero_node is just a NOP. */
1561 expand_eh_region_end (size_zero_node);
1564 INSN_UID (node->entry->outer_context) = 0;
1567 /* If we are using the setjmp/longjmp EH codegen method, we emit a
1570 Otherwise, we emit a call to __throw and note that we threw
1571 something, so we know we need to generate the necessary code for
1574 Before invoking throw, the __eh_pc variable must have been set up
1575 to contain the PC being thrown from. This address is used by
1576 __throw to determine which exception region (if any) is
1577 responsible for handling the exception. */
1582 if (exceptions_via_longjmp)
1584 emit_library_call (sjthrow_libfunc, 0, VOIDmode, 0);
1588 #ifdef JUMP_TO_THROW
1589 emit_indirect_jump (throw_libfunc);
1591 emit_library_call (throw_libfunc, 0, VOIDmode, 0);
1597 /* Throw the current exception. If appropriate, this is done by jumping
1598 to the next handler. */
1601 expand_internal_throw ()
1606 /* Called from expand_exception_blocks and expand_end_catch_block to
1607 emit any pending handlers/cleanups queued from expand_eh_region_end. */
1610 expand_leftover_cleanups ()
1612 struct eh_entry *entry;
1614 while ((entry = dequeue_eh_entry (&ehqueue)) != 0)
1618 /* A leftover try block. Shouldn't be one here. */
1619 if (entry->finalization == integer_zero_node)
1622 /* Output the label for the start of the exception handler. */
1624 receive_exception_label (entry->exception_handler_label);
1626 /* register a handler for this cleanup region */
1628 find_func_region (CODE_LABEL_NUMBER (entry->exception_handler_label)),
1629 get_new_handler (entry->exception_handler_label, NULL));
1631 /* And now generate the insns for the handler. */
1632 expand_expr (entry->finalization, const0_rtx, VOIDmode, 0);
1634 prev = get_last_insn ();
1635 if (prev == NULL || GET_CODE (prev) != BARRIER)
1636 /* Emit code to throw to the outer context if we fall off
1637 the end of the handler. */
1638 expand_rethrow (entry->outer_context);
1640 do_pending_stack_adjust ();
1645 /* Called at the start of a block of try statements. */
1647 expand_start_try_stmts ()
1652 expand_eh_region_start ();
1655 /* Called to begin a catch clause. The parameter is the object which
1656 will be passed to the runtime type check routine. */
1658 start_catch_handler (rtime)
1662 int insn_region_num;
1663 int eh_region_entry;
1668 handler_label = catchstack.top->entry->exception_handler_label;
1669 insn_region_num = CODE_LABEL_NUMBER (handler_label);
1670 eh_region_entry = find_func_region (insn_region_num);
1672 /* If we've already issued this label, pick a new one */
1673 if (catchstack.top->entry->label_used)
1674 handler_label = gen_exception_label ();
1676 catchstack.top->entry->label_used = 1;
1678 receive_exception_label (handler_label);
1680 add_new_handler (eh_region_entry, get_new_handler (handler_label, rtime));
1682 if (flag_new_exceptions && ! exceptions_via_longjmp)
1685 /* Under the old mechanism, as well as setjmp/longjmp, we need to
1686 issue code to compare 'rtime' to the value in eh_info, via the
1687 matching function in eh_info. If its is false, we branch around
1688 the handler we are about to issue. */
1690 if (rtime != NULL_TREE && rtime != CATCH_ALL_TYPE)
1692 rtx call_rtx, rtime_address;
1694 if (catchstack.top->entry->false_label != NULL_RTX)
1695 fatal ("Compiler Bug: Never issued previous false_label");
1696 catchstack.top->entry->false_label = gen_exception_label ();
1698 rtime_address = expand_expr (rtime, NULL_RTX, Pmode, EXPAND_INITIALIZER);
1699 #ifdef POINTERS_EXTEND_UNSIGNED
1700 rtime_address = convert_memory_address (Pmode, rtime_address);
1702 rtime_address = force_reg (Pmode, rtime_address);
1704 /* Now issue the call, and branch around handler if needed */
1705 call_rtx = emit_library_call_value (eh_rtime_match_libfunc, NULL_RTX,
1706 0, SImode, 1, rtime_address, Pmode);
1708 /* Did the function return true? */
1709 emit_cmp_and_jump_insns (call_rtx, const0_rtx, EQ, NULL_RTX,
1710 GET_MODE (call_rtx), 0, 0,
1711 catchstack.top->entry->false_label);
1715 /* Called to end a catch clause. If we aren't using the new exception
1716 model tabel mechanism, we need to issue the branch-around label
1717 for the end of the catch block. */
1720 end_catch_handler ()
1725 if (flag_new_exceptions && ! exceptions_via_longjmp)
1731 /* A NULL label implies the catch clause was a catch all or cleanup */
1732 if (catchstack.top->entry->false_label == NULL_RTX)
1735 emit_label (catchstack.top->entry->false_label);
1736 catchstack.top->entry->false_label = NULL_RTX;
1739 /* Generate RTL for the start of a group of catch clauses.
1741 It is responsible for starting a new instruction sequence for the
1742 instructions in the catch block, and expanding the handlers for the
1743 internally-generated exception regions nested within the try block
1744 corresponding to this catch block. */
1747 expand_start_all_catch ()
1749 struct eh_entry *entry;
1756 outer_context = ehstack.top->entry->outer_context;
1758 /* End the try block. */
1759 expand_eh_region_end (integer_zero_node);
1761 emit_line_note (input_filename, lineno);
1762 label = build_decl (LABEL_DECL, NULL_TREE, NULL_TREE);
1764 /* The label for the exception handling block that we will save.
1765 This is Lresume in the documentation. */
1766 expand_label (label);
1768 /* Push the label that points to where normal flow is resumed onto
1769 the top of the label stack. */
1770 push_label_entry (&caught_return_label_stack, NULL_RTX, label);
1772 /* Start a new sequence for all the catch blocks. We will add this
1773 to the global sequence catch_clauses when we have completed all
1774 the handlers in this handler-seq. */
1777 entry = dequeue_eh_entry (&ehqueue);
1778 for ( ; entry->finalization != integer_zero_node;
1779 entry = dequeue_eh_entry (&ehqueue))
1783 /* Emit the label for the cleanup handler for this region, and
1784 expand the code for the handler.
1786 Note that a catch region is handled as a side-effect here;
1787 for a try block, entry->finalization will contain
1788 integer_zero_node, so no code will be generated in the
1789 expand_expr call below. But, the label for the handler will
1790 still be emitted, so any code emitted after this point will
1791 end up being the handler. */
1793 receive_exception_label (entry->exception_handler_label);
1795 /* register a handler for this cleanup region */
1797 find_func_region (CODE_LABEL_NUMBER (entry->exception_handler_label)),
1798 get_new_handler (entry->exception_handler_label, NULL));
1800 /* And now generate the insns for the cleanup handler. */
1801 expand_expr (entry->finalization, const0_rtx, VOIDmode, 0);
1803 prev = get_last_insn ();
1804 if (prev == NULL || GET_CODE (prev) != BARRIER)
1805 /* Code to throw out to outer context when we fall off end
1806 of the handler. We can't do this here for catch blocks,
1807 so it's done in expand_end_all_catch instead. */
1808 expand_rethrow (entry->outer_context);
1810 do_pending_stack_adjust ();
1814 /* At this point, all the cleanups are done, and the ehqueue now has
1815 the current exception region at its head. We dequeue it, and put it
1816 on the catch stack. */
1818 push_entry (&catchstack, entry);
1820 /* If we are not doing setjmp/longjmp EH, because we are reordered
1821 out of line, we arrange to rethrow in the outer context. We need to
1822 do this because we are not physically within the region, if any, that
1823 logically contains this catch block. */
1824 if (! exceptions_via_longjmp)
1826 expand_eh_region_start ();
1827 ehstack.top->entry->outer_context = outer_context;
1832 /* Finish up the catch block. At this point all the insns for the
1833 catch clauses have already been generated, so we only have to add
1834 them to the catch_clauses list. We also want to make sure that if
1835 we fall off the end of the catch clauses that we rethrow to the
1839 expand_end_all_catch ()
1841 rtx new_catch_clause;
1842 struct eh_entry *entry;
1847 /* Dequeue the current catch clause region. */
1848 entry = pop_eh_entry (&catchstack);
1851 if (! exceptions_via_longjmp)
1853 rtx outer_context = ehstack.top->entry->outer_context;
1855 /* Finish the rethrow region. size_zero_node is just a NOP. */
1856 expand_eh_region_end (size_zero_node);
1857 /* New exceptions handling models will never have a fall through
1858 of a catch clause */
1859 if (!flag_new_exceptions)
1860 expand_rethrow (outer_context);
1863 expand_rethrow (NULL_RTX);
1865 /* Code to throw out to outer context, if we fall off end of catch
1866 handlers. This is rethrow (Lresume, same id, same obj) in the
1867 documentation. We use Lresume because we know that it will throw
1868 to the correct context.
1870 In other words, if the catch handler doesn't exit or return, we
1871 do a "throw" (using the address of Lresume as the point being
1872 thrown from) so that the outer EH region can then try to process
1875 /* Now we have the complete catch sequence. */
1876 new_catch_clause = get_insns ();
1879 /* This level of catch blocks is done, so set up the successful
1880 catch jump label for the next layer of catch blocks. */
1881 pop_label_entry (&caught_return_label_stack);
1882 pop_label_entry (&outer_context_label_stack);
1884 /* Add the new sequence of catches to the main one for this function. */
1885 push_to_sequence (catch_clauses);
1886 emit_insns (new_catch_clause);
1887 catch_clauses = get_insns ();
1890 /* Here we fall through into the continuation code. */
1893 /* Rethrow from the outer context LABEL. */
1896 expand_rethrow (label)
1899 if (exceptions_via_longjmp)
1902 if (flag_new_exceptions)
1906 if (label == NULL_RTX)
1907 label = last_rethrow_symbol;
1908 emit_library_call (rethrow_libfunc, 0, VOIDmode, 1, label, Pmode);
1909 region = find_func_region (eh_region_from_symbol (label));
1910 function_eh_regions[region].rethrow_ref = 1;
1912 /* Search backwards for the actual call insn. */
1913 insn = get_last_insn ();
1914 while (GET_CODE (insn) != CALL_INSN)
1915 insn = PREV_INSN (insn);
1916 delete_insns_since (insn);
1918 /* Mark the label/symbol on the call. */
1919 REG_NOTES (insn) = gen_rtx_EXPR_LIST (REG_EH_RETHROW, label,
1927 /* End all the pending exception regions on protect_list. The handlers
1928 will be emitted when expand_leftover_cleanups is invoked. */
1931 end_protect_partials ()
1933 while (protect_list)
1935 expand_eh_region_end (TREE_VALUE (protect_list));
1936 protect_list = TREE_CHAIN (protect_list);
1940 /* Arrange for __terminate to be called if there is an unhandled throw
1944 protect_with_terminate (e)
1947 /* We only need to do this when using setjmp/longjmp EH and the
1948 language requires it, as otherwise we protect all of the handlers
1949 at once, if we need to. */
1950 if (exceptions_via_longjmp && protect_cleanup_actions_with_terminate)
1952 tree handler, result;
1954 /* All cleanups must be on the function_obstack. */
1955 push_obstacks_nochange ();
1956 resume_temporary_allocation ();
1958 handler = make_node (RTL_EXPR);
1959 TREE_TYPE (handler) = void_type_node;
1960 RTL_EXPR_RTL (handler) = const0_rtx;
1961 TREE_SIDE_EFFECTS (handler) = 1;
1962 start_sequence_for_rtl_expr (handler);
1964 emit_library_call (terminate_libfunc, 0, VOIDmode, 0);
1967 RTL_EXPR_SEQUENCE (handler) = get_insns ();
1970 result = build (TRY_CATCH_EXPR, TREE_TYPE (e), e, handler);
1971 TREE_SIDE_EFFECTS (result) = TREE_SIDE_EFFECTS (e);
1972 TREE_THIS_VOLATILE (result) = TREE_THIS_VOLATILE (e);
1973 TREE_READONLY (result) = TREE_READONLY (e);
1983 /* The exception table that we build that is used for looking up and
1984 dispatching exceptions, the current number of entries, and its
1985 maximum size before we have to extend it.
1987 The number in eh_table is the code label number of the exception
1988 handler for the region. This is added by add_eh_table_entry and
1989 used by output_exception_table_entry. */
1991 static int *eh_table = NULL;
1992 static int eh_table_size = 0;
1993 static int eh_table_max_size = 0;
1995 /* Note the need for an exception table entry for region N. If we
1996 don't need to output an explicit exception table, avoid all of the
1999 Called from final_scan_insn when a NOTE_INSN_EH_REGION_BEG is seen.
2000 (Or NOTE_INSN_EH_REGION_END sometimes)
2001 N is the NOTE_BLOCK_NUMBER of the note, which comes from the code
2002 label number of the exception handler for the region. */
2005 add_eh_table_entry (n)
2008 #ifndef OMIT_EH_TABLE
2009 if (eh_table_size >= eh_table_max_size)
2013 eh_table_max_size += eh_table_max_size>>1;
2015 if (eh_table_max_size < 0)
2018 eh_table = (int *) xrealloc (eh_table,
2019 eh_table_max_size * sizeof (int));
2023 eh_table_max_size = 252;
2024 eh_table = (int *) xmalloc (eh_table_max_size * sizeof (int));
2027 eh_table[eh_table_size++] = n;
2031 /* Return a non-zero value if we need to output an exception table.
2033 On some platforms, we don't have to output a table explicitly.
2034 This routine doesn't mean we don't have one. */
2037 exception_table_p ()
2045 /* Output the entry of the exception table corresponding to the
2046 exception region numbered N to file FILE.
2048 N is the code label number corresponding to the handler of the
2052 output_exception_table_entry (file, n)
2058 struct handler_info *handler = get_first_handler (n);
2059 int index = find_func_region (n);
2062 /* form and emit the rethrow label, if needed */
2063 rethrow = function_eh_regions[index].rethrow_label;
2064 if (rethrow != NULL_RTX && !flag_new_exceptions)
2066 if (rethrow != NULL_RTX && handler == NULL)
2067 if (! function_eh_regions[index].rethrow_ref)
2071 for ( ; handler != NULL || rethrow != NULL_RTX; handler = handler->next)
2073 /* rethrow label should indicate the LAST entry for a region */
2074 if (rethrow != NULL_RTX && (handler == NULL || handler->next == NULL))
2076 ASM_GENERATE_INTERNAL_LABEL (buf, "LRTH", n);
2077 assemble_label(buf);
2081 ASM_GENERATE_INTERNAL_LABEL (buf, "LEHB", n);
2082 sym = gen_rtx_SYMBOL_REF (Pmode, buf);
2083 assemble_integer (sym, POINTER_SIZE / BITS_PER_UNIT, 1);
2085 ASM_GENERATE_INTERNAL_LABEL (buf, "LEHE", n);
2086 sym = gen_rtx_SYMBOL_REF (Pmode, buf);
2087 assemble_integer (sym, POINTER_SIZE / BITS_PER_UNIT, 1);
2089 if (handler == NULL)
2090 assemble_integer (GEN_INT (0), POINTER_SIZE / BITS_PER_UNIT, 1);
2093 ASM_GENERATE_INTERNAL_LABEL (buf, "L", handler->handler_number);
2094 sym = gen_rtx_SYMBOL_REF (Pmode, buf);
2095 assemble_integer (sym, POINTER_SIZE / BITS_PER_UNIT, 1);
2098 if (flag_new_exceptions)
2100 if (handler == NULL || handler->type_info == NULL)
2101 assemble_integer (const0_rtx, POINTER_SIZE / BITS_PER_UNIT, 1);
2103 if (handler->type_info == CATCH_ALL_TYPE)
2104 assemble_integer (GEN_INT (CATCH_ALL_TYPE),
2105 POINTER_SIZE / BITS_PER_UNIT, 1);
2107 output_constant ((tree)(handler->type_info),
2108 POINTER_SIZE / BITS_PER_UNIT);
2110 putc ('\n', file); /* blank line */
2111 /* We only output the first label under the old scheme */
2112 if (! flag_new_exceptions || handler == NULL)
2117 /* Output the exception table if we have and need one. */
2119 static short language_code = 0;
2120 static short version_code = 0;
2122 /* This routine will set the language code for exceptions. */
2124 set_exception_lang_code (code)
2127 language_code = code;
2130 /* This routine will set the language version code for exceptions. */
2132 set_exception_version_code (code)
2135 version_code = code;
2140 output_exception_table ()
2144 extern FILE *asm_out_file;
2146 if (! doing_eh (0) || ! eh_table)
2149 exception_section ();
2151 /* Beginning marker for table. */
2152 assemble_align (GET_MODE_ALIGNMENT (ptr_mode));
2153 assemble_label ("__EXCEPTION_TABLE__");
2155 if (flag_new_exceptions)
2157 assemble_integer (GEN_INT (NEW_EH_RUNTIME),
2158 POINTER_SIZE / BITS_PER_UNIT, 1);
2159 assemble_integer (GEN_INT (language_code), 2 , 1);
2160 assemble_integer (GEN_INT (version_code), 2 , 1);
2162 /* Add enough padding to make sure table aligns on a pointer boundry. */
2163 i = GET_MODE_ALIGNMENT (ptr_mode) / BITS_PER_UNIT - 4;
2164 for ( ; i < 0; i = i + GET_MODE_ALIGNMENT (ptr_mode) / BITS_PER_UNIT)
2167 assemble_integer (const0_rtx, i , 1);
2169 /* Generate the label for offset calculations on rethrows */
2170 ASM_GENERATE_INTERNAL_LABEL (buf, "LRTH", 0);
2171 assemble_label(buf);
2174 for (i = 0; i < eh_table_size; ++i)
2175 output_exception_table_entry (asm_out_file, eh_table[i]);
2178 clear_function_eh_region ();
2180 /* Ending marker for table. */
2181 /* Generate the label for end of table. */
2182 ASM_GENERATE_INTERNAL_LABEL (buf, "LRTH", CODE_LABEL_NUMBER (final_rethrow));
2183 assemble_label(buf);
2184 assemble_integer (constm1_rtx, POINTER_SIZE / BITS_PER_UNIT, 1);
2186 /* for binary compatability, the old __throw checked the second
2187 position for a -1, so we should output at least 2 -1's */
2188 if (! flag_new_exceptions)
2189 assemble_integer (constm1_rtx, POINTER_SIZE / BITS_PER_UNIT, 1);
2191 putc ('\n', asm_out_file); /* blank line */
2194 /* Emit code to get EH context.
2196 We have to scan thru the code to find possible EH context registers.
2197 Inlined functions may use it too, and thus we'll have to be able
2200 This is done only if using exceptions_via_longjmp. */
2211 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
2212 if (GET_CODE (insn) == INSN
2213 && GET_CODE (PATTERN (insn)) == USE)
2215 rtx reg = find_reg_note (insn, REG_EH_CONTEXT, 0);
2222 /* If this is the first use insn, emit the call here. This
2223 will always be at the top of our function, because if
2224 expand_inline_function notices a REG_EH_CONTEXT note, it
2225 adds a use insn to this function as well. */
2227 ehc = call_get_eh_context ();
2229 emit_move_insn (XEXP (reg, 0), ehc);
2230 insns = get_insns ();
2233 emit_insns_before (insns, insn);
2235 /* At -O0, we must make the context register stay alive so
2236 that the stupid.c register allocator doesn't get confused. */
2237 if (obey_regdecls != 0)
2239 insns = gen_rtx_USE (GET_MODE (XEXP (reg,0)), XEXP (reg,0));
2240 emit_insn_before (insns, get_last_insn ());
2246 /* Scan the current insns and build a list of handler labels. The
2247 resulting list is placed in the global variable exception_handler_labels.
2249 It is called after the last exception handling region is added to
2250 the current function (when the rtl is almost all built for the
2251 current function) and before the jump optimization pass. */
2254 find_exception_handler_labels ()
2258 exception_handler_labels = NULL_RTX;
2260 /* If we aren't doing exception handling, there isn't much to check. */
2264 /* For each start of a region, add its label to the list. */
2266 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
2268 struct handler_info* ptr;
2269 if (GET_CODE (insn) == NOTE
2270 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG)
2272 ptr = get_first_handler (NOTE_BLOCK_NUMBER (insn));
2273 for ( ; ptr; ptr = ptr->next)
2275 /* make sure label isn't in the list already */
2277 for (x = exception_handler_labels; x; x = XEXP (x, 1))
2278 if (XEXP (x, 0) == ptr->handler_label)
2281 exception_handler_labels = gen_rtx_EXPR_LIST (VOIDmode,
2282 ptr->handler_label, exception_handler_labels);
2288 /* Return a value of 1 if the parameter label number is an exception handler
2289 label. Return 0 otherwise. */
2292 is_exception_handler_label (lab)
2296 for (x = exception_handler_labels ; x ; x = XEXP (x, 1))
2297 if (lab == CODE_LABEL_NUMBER (XEXP (x, 0)))
2302 /* Perform sanity checking on the exception_handler_labels list.
2304 Can be called after find_exception_handler_labels is called to
2305 build the list of exception handlers for the current function and
2306 before we finish processing the current function. */
2309 check_exception_handler_labels ()
2313 /* If we aren't doing exception handling, there isn't much to check. */
2317 /* Make sure there is no more than 1 copy of a label */
2318 for (insn = exception_handler_labels; insn; insn = XEXP (insn, 1))
2321 for (insn2 = exception_handler_labels; insn2; insn2 = XEXP (insn2, 1))
2322 if (XEXP (insn, 0) == XEXP (insn2, 0))
2325 warning ("Counted %d copies of EH region %d in list.\n", count,
2326 CODE_LABEL_NUMBER (insn));
2331 /* This group of functions initializes the exception handling data
2332 structures at the start of the compilation, initializes the data
2333 structures at the start of a function, and saves and restores the
2334 exception handling data structures for the start/end of a nested
2337 /* Toplevel initialization for EH things. */
2342 first_rethrow_symbol = create_rethrow_ref (0);
2343 final_rethrow = gen_exception_label ();
2344 last_rethrow_symbol = create_rethrow_ref (CODE_LABEL_NUMBER (final_rethrow));
2347 /* Initialize the per-function EH information. */
2350 init_eh_for_function ()
2352 current_function->eh = (struct eh_status *) xmalloc (sizeof (struct eh_status));
2356 ehqueue.head = ehqueue.tail = 0;
2357 catch_clauses = NULL_RTX;
2358 false_label_stack = 0;
2359 caught_return_label_stack = 0;
2360 protect_list = NULL_TREE;
2361 current_function_ehc = NULL_RTX;
2362 eh_return_context = NULL_RTX;
2363 eh_return_stack_adjust = NULL_RTX;
2364 eh_return_handler = NULL_RTX;
2365 eh_return_stub_label = NULL_RTX;
2368 /* This section is for the exception handling specific optimization
2369 pass. First are the internal routines, and then the main
2370 optimization pass. */
2372 /* Determine if the given INSN can throw an exception. */
2378 /* Calls can always potentially throw exceptions, unless they have
2379 a REG_EH_REGION note with a value of 0 or less. */
2380 if (GET_CODE (insn) == CALL_INSN)
2382 rtx note = find_reg_note (insn, REG_EH_REGION, NULL_RTX);
2383 if (!note || XINT (XEXP (note, 0), 0) > 0)
2387 if (asynchronous_exceptions)
2389 /* If we wanted asynchronous exceptions, then everything but NOTEs
2390 and CODE_LABELs could throw. */
2391 if (GET_CODE (insn) != NOTE && GET_CODE (insn) != CODE_LABEL)
2398 /* Scan a exception region looking for the matching end and then
2399 remove it if possible. INSN is the start of the region, N is the
2400 region number, and DELETE_OUTER is to note if anything in this
2403 Regions are removed if they cannot possibly catch an exception.
2404 This is determined by invoking can_throw on each insn within the
2405 region; if can_throw returns true for any of the instructions, the
2406 region can catch an exception, since there is an insn within the
2407 region that is capable of throwing an exception.
2409 Returns the NOTE_INSN_EH_REGION_END corresponding to this region, or
2410 calls abort if it can't find one.
2412 Can abort if INSN is not a NOTE_INSN_EH_REGION_BEGIN, or if N doesn't
2413 correspond to the region number, or if DELETE_OUTER is NULL. */
2416 scan_region (insn, n, delete_outer)
2423 /* Assume we can delete the region. */
2426 /* Can't delete something which is rethrown to. */
2427 if (rethrow_used (n))
2430 if (insn == NULL_RTX
2431 || GET_CODE (insn) != NOTE
2432 || NOTE_LINE_NUMBER (insn) != NOTE_INSN_EH_REGION_BEG
2433 || NOTE_BLOCK_NUMBER (insn) != n
2434 || delete_outer == NULL)
2437 insn = NEXT_INSN (insn);
2439 /* Look for the matching end. */
2440 while (! (GET_CODE (insn) == NOTE
2441 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_END))
2443 /* If anything can throw, we can't remove the region. */
2444 if (delete && can_throw (insn))
2449 /* Watch out for and handle nested regions. */
2450 if (GET_CODE (insn) == NOTE
2451 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG)
2453 insn = scan_region (insn, NOTE_BLOCK_NUMBER (insn), &delete);
2456 insn = NEXT_INSN (insn);
2459 /* The _BEG/_END NOTEs must match and nest. */
2460 if (NOTE_BLOCK_NUMBER (insn) != n)
2463 /* If anything in this exception region can throw, we can throw. */
2468 /* Delete the start and end of the region. */
2469 delete_insn (start);
2472 /* We no longer removed labels here, since flow will now remove any
2473 handler which cannot be called any more. */
2476 /* Only do this part if we have built the exception handler
2478 if (exception_handler_labels)
2480 rtx x, *prev = &exception_handler_labels;
2482 /* Find it in the list of handlers. */
2483 for (x = exception_handler_labels; x; x = XEXP (x, 1))
2485 rtx label = XEXP (x, 0);
2486 if (CODE_LABEL_NUMBER (label) == n)
2488 /* If we are the last reference to the handler,
2490 if (--LABEL_NUSES (label) == 0)
2491 delete_insn (label);
2495 /* Remove it from the list of exception handler
2496 labels, if we are optimizing. If we are not, then
2497 leave it in the list, as we are not really going to
2498 remove the region. */
2499 *prev = XEXP (x, 1);
2506 prev = &XEXP (x, 1);
2514 /* Perform various interesting optimizations for exception handling
2517 We look for empty exception regions and make them go (away). The
2518 jump optimization code will remove the handler if nothing else uses
2522 exception_optimize ()
2527 /* Remove empty regions. */
2528 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
2530 if (GET_CODE (insn) == NOTE
2531 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG)
2533 /* Since scan_region will return the NOTE_INSN_EH_REGION_END
2534 insn, we will indirectly skip through all the insns
2535 inbetween. We are also guaranteed that the value of insn
2536 returned will be valid, as otherwise scan_region won't
2538 insn = scan_region (insn, NOTE_BLOCK_NUMBER (insn), &n);
2543 /* This function determines whether any of the exception regions in the
2544 current function are targets of a rethrow or not, and set the
2545 reference flag according. */
2547 update_rethrow_references ()
2551 int *saw_region, *saw_rethrow;
2553 if (!flag_new_exceptions)
2556 saw_region = (int *) alloca (current_func_eh_entry * sizeof (int));
2557 saw_rethrow = (int *) alloca (current_func_eh_entry * sizeof (int));
2558 bzero ((char *) saw_region, (current_func_eh_entry * sizeof (int)));
2559 bzero ((char *) saw_rethrow, (current_func_eh_entry * sizeof (int)));
2561 /* Determine what regions exist, and whether there are any rethrows
2562 to those regions or not. */
2563 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
2564 if (GET_CODE (insn) == CALL_INSN)
2566 rtx note = find_reg_note (insn, REG_EH_RETHROW, NULL_RTX);
2569 region = eh_region_from_symbol (XEXP (note, 0));
2570 region = find_func_region (region);
2571 saw_rethrow[region] = 1;
2575 if (GET_CODE (insn) == NOTE)
2577 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG)
2579 region = find_func_region (NOTE_BLOCK_NUMBER (insn));
2580 saw_region[region] = 1;
2584 /* For any regions we did see, set the referenced flag. */
2585 for (x = 0; x < current_func_eh_entry; x++)
2587 function_eh_regions[x].rethrow_ref = saw_rethrow[x];
2590 /* Various hooks for the DWARF 2 __throw routine. */
2592 /* Do any necessary initialization to access arbitrary stack frames.
2593 On the SPARC, this means flushing the register windows. */
2596 expand_builtin_unwind_init ()
2598 /* Set this so all the registers get saved in our frame; we need to be
2599 able to copy the saved values for any registers from frames we unwind. */
2600 current_function_has_nonlocal_label = 1;
2602 #ifdef SETUP_FRAME_ADDRESSES
2603 SETUP_FRAME_ADDRESSES ();
2607 /* Given a value extracted from the return address register or stack slot,
2608 return the actual address encoded in that value. */
2611 expand_builtin_extract_return_addr (addr_tree)
2614 rtx addr = expand_expr (addr_tree, NULL_RTX, Pmode, 0);
2615 return eh_outer_context (addr);
2618 /* Given an actual address in addr_tree, do any necessary encoding
2619 and return the value to be stored in the return address register or
2620 stack slot so the epilogue will return to that address. */
2623 expand_builtin_frob_return_addr (addr_tree)
2626 rtx addr = expand_expr (addr_tree, NULL_RTX, Pmode, 0);
2627 #ifdef RETURN_ADDR_OFFSET
2628 addr = plus_constant (addr, -RETURN_ADDR_OFFSET);
2633 /* Choose three registers for communication between the main body of
2634 __throw and the epilogue (or eh stub) and the exception handler.
2635 We must do this with hard registers because the epilogue itself
2636 will be generated after reload, at which point we may not reference
2639 The first passes the exception context to the handler. For this
2640 we use the return value register for a void*.
2642 The second holds the stack pointer value to be restored. For
2643 this we use the static chain register if it exists and is different
2644 from the previous, otherwise some arbitrary call-clobbered register.
2646 The third holds the address of the handler itself. Here we use
2647 some arbitrary call-clobbered register. */
2650 eh_regs (pcontext, psp, pra, outgoing)
2651 rtx *pcontext, *psp, *pra;
2654 rtx rcontext, rsp, rra;
2657 #ifdef FUNCTION_OUTGOING_VALUE
2659 rcontext = FUNCTION_OUTGOING_VALUE (build_pointer_type (void_type_node),
2660 current_function_decl);
2663 rcontext = FUNCTION_VALUE (build_pointer_type (void_type_node),
2664 current_function_decl);
2666 #ifdef STATIC_CHAIN_REGNUM
2668 rsp = static_chain_incoming_rtx;
2670 rsp = static_chain_rtx;
2671 if (REGNO (rsp) == REGNO (rcontext))
2672 #endif /* STATIC_CHAIN_REGNUM */
2675 if (rsp == NULL_RTX)
2677 for (i = 0; i < FIRST_PSEUDO_REGISTER; ++i)
2678 if (call_used_regs[i] && ! fixed_regs[i] && i != REGNO (rcontext))
2680 if (i == FIRST_PSEUDO_REGISTER)
2683 rsp = gen_rtx_REG (Pmode, i);
2686 for (i = 0; i < FIRST_PSEUDO_REGISTER; ++i)
2687 if (call_used_regs[i] && ! fixed_regs[i]
2688 && i != REGNO (rcontext) && i != REGNO (rsp))
2690 if (i == FIRST_PSEUDO_REGISTER)
2693 rra = gen_rtx_REG (Pmode, i);
2695 *pcontext = rcontext;
2700 /* Retrieve the register which contains the pointer to the eh_context
2701 structure set the __throw. */
2704 get_reg_for_handler ()
2707 reg1 = FUNCTION_VALUE (build_pointer_type (void_type_node),
2708 current_function_decl);
2712 /* Set up the epilogue with the magic bits we'll need to return to the
2713 exception handler. */
2716 expand_builtin_eh_return (context, stack, handler)
2717 tree context, stack, handler;
2719 if (eh_return_context)
2720 error("Duplicate call to __builtin_eh_return");
2723 = copy_to_reg (expand_expr (context, NULL_RTX, VOIDmode, 0));
2724 eh_return_stack_adjust
2725 = copy_to_reg (expand_expr (stack, NULL_RTX, VOIDmode, 0));
2727 = copy_to_reg (expand_expr (handler, NULL_RTX, VOIDmode, 0));
2733 rtx reg1, reg2, reg3;
2734 rtx stub_start, after_stub;
2737 if (!eh_return_context)
2740 current_function_cannot_inline = N_("function uses __builtin_eh_return");
2742 eh_regs (®1, ®2, ®3, 1);
2743 #ifdef POINTERS_EXTEND_UNSIGNED
2744 eh_return_context = convert_memory_address (Pmode, eh_return_context);
2745 eh_return_stack_adjust =
2746 convert_memory_address (Pmode, eh_return_stack_adjust);
2747 eh_return_handler = convert_memory_address (Pmode, eh_return_handler);
2749 emit_move_insn (reg1, eh_return_context);
2750 emit_move_insn (reg2, eh_return_stack_adjust);
2751 emit_move_insn (reg3, eh_return_handler);
2753 /* Talk directly to the target's epilogue code when possible. */
2755 #ifdef HAVE_eh_epilogue
2756 if (HAVE_eh_epilogue)
2758 emit_insn (gen_eh_epilogue (reg1, reg2, reg3));
2763 /* Otherwise, use the same stub technique we had before. */
2765 eh_return_stub_label = stub_start = gen_label_rtx ();
2766 after_stub = gen_label_rtx ();
2768 /* Set the return address to the stub label. */
2770 ra = expand_builtin_return_addr (BUILT_IN_RETURN_ADDRESS,
2771 0, hard_frame_pointer_rtx);
2772 if (GET_CODE (ra) == REG && REGNO (ra) >= FIRST_PSEUDO_REGISTER)
2775 tmp = memory_address (Pmode, gen_rtx_LABEL_REF (Pmode, stub_start));
2776 #ifdef RETURN_ADDR_OFFSET
2777 tmp = plus_constant (tmp, -RETURN_ADDR_OFFSET);
2779 tmp = force_operand (tmp, ra);
2781 emit_move_insn (ra, tmp);
2783 /* Indicate that the registers are in fact used. */
2784 emit_insn (gen_rtx_USE (VOIDmode, reg1));
2785 emit_insn (gen_rtx_USE (VOIDmode, reg2));
2786 emit_insn (gen_rtx_USE (VOIDmode, reg3));
2787 if (GET_CODE (ra) == REG)
2788 emit_insn (gen_rtx_USE (VOIDmode, ra));
2790 /* Generate the stub. */
2792 emit_jump (after_stub);
2793 emit_label (stub_start);
2795 eh_regs (®1, ®2, ®3, 0);
2796 adjust_stack (reg2);
2797 emit_indirect_jump (reg3);
2799 emit_label (after_stub);
2803 /* This contains the code required to verify whether arbitrary instructions
2804 are in the same exception region. */
2806 static int *insn_eh_region = (int *)0;
2807 static int maximum_uid;
2810 set_insn_eh_region (first, region_num)
2817 for (insn = *first; insn; insn = NEXT_INSN (insn))
2819 if ((GET_CODE (insn) == NOTE) &&
2820 (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG))
2822 rnum = NOTE_BLOCK_NUMBER (insn);
2823 insn_eh_region[INSN_UID (insn)] = rnum;
2824 insn = NEXT_INSN (insn);
2825 set_insn_eh_region (&insn, rnum);
2826 /* Upon return, insn points to the EH_REGION_END of nested region */
2829 insn_eh_region[INSN_UID (insn)] = region_num;
2830 if ((GET_CODE (insn) == NOTE) &&
2831 (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_END))
2837 /* Free the insn table, an make sure it cannot be used again. */
2840 free_insn_eh_region ()
2847 free (insn_eh_region);
2848 insn_eh_region = (int *)0;
2852 /* Initialize the table. max_uid must be calculated and handed into
2853 this routine. If it is unavailable, passing a value of 0 will
2854 cause this routine to calculate it as well. */
2857 init_insn_eh_region (first, max_uid)
2867 free_insn_eh_region();
2870 for (insn = first; insn; insn = NEXT_INSN (insn))
2871 if (INSN_UID (insn) > max_uid) /* find largest UID */
2872 max_uid = INSN_UID (insn);
2874 maximum_uid = max_uid;
2875 insn_eh_region = (int *) malloc ((max_uid + 1) * sizeof (int));
2877 set_insn_eh_region (&insn, 0);
2881 /* Check whether 2 instructions are within the same region. */
2884 in_same_eh_region (insn1, insn2)
2887 int ret, uid1, uid2;
2889 /* If no exceptions, instructions are always in same region. */
2893 /* If the table isn't allocated, assume the worst. */
2894 if (!insn_eh_region)
2897 uid1 = INSN_UID (insn1);
2898 uid2 = INSN_UID (insn2);
2900 /* if instructions have been allocated beyond the end, either
2901 the table is out of date, or this is a late addition, or
2902 something... Assume the worst. */
2903 if (uid1 > maximum_uid || uid2 > maximum_uid)
2906 ret = (insn_eh_region[uid1] == insn_eh_region[uid2]);
2911 /* This function will initialize the handler list for a specified block.
2912 It may recursively call itself if the outer block hasn't been processed
2913 yet. At some point in the future we can trim out handlers which we
2914 know cannot be called. (ie, if a block has an INT type handler,
2915 control will never be passed to an outer INT type handler). */
2917 process_nestinfo (block, info, nested_eh_region)
2919 eh_nesting_info *info;
2920 int *nested_eh_region;
2922 handler_info *ptr, *last_ptr = NULL;
2923 int x, y, count = 0;
2925 handler_info **extra_handlers;
2926 int index = info->region_index[block];
2928 /* If we've already processed this block, simply return. */
2929 if (info->num_handlers[index] > 0)
2932 for (ptr = get_first_handler (block); ptr; last_ptr = ptr, ptr = ptr->next)
2935 /* pick up any information from the next outer region. It will already
2936 contain a summary of itself and all outer regions to it. */
2938 if (nested_eh_region [block] != 0)
2940 int nested_index = info->region_index[nested_eh_region[block]];
2941 process_nestinfo (nested_eh_region[block], info, nested_eh_region);
2942 extra = info->num_handlers[nested_index];
2943 extra_handlers = info->handlers[nested_index];
2944 info->outer_index[index] = nested_index;
2947 /* If the last handler is either a CATCH_ALL or a cleanup, then we
2948 won't use the outer ones since we know control will not go past the
2949 catch-all or cleanup. */
2951 if (last_ptr != NULL && (last_ptr->type_info == NULL
2952 || last_ptr->type_info == CATCH_ALL_TYPE))
2955 info->num_handlers[index] = count + extra;
2956 info->handlers[index] = (handler_info **) malloc ((count + extra)
2957 * sizeof (handler_info **));
2959 /* First put all our handlers into the list. */
2960 ptr = get_first_handler (block);
2961 for (x = 0; x < count; x++)
2963 info->handlers[index][x] = ptr;
2967 /* Now add all the outer region handlers, if they aren't they same as
2968 one of the types in the current block. We won't worry about
2969 derived types yet, we'll just look for the exact type. */
2970 for (y =0, x = 0; x < extra ; x++)
2974 /* Check to see if we have a type duplication. */
2975 for (i = 0; i < count; i++)
2976 if (info->handlers[index][i]->type_info == extra_handlers[x]->type_info)
2979 /* Record one less handler. */
2980 (info->num_handlers[index])--;
2985 info->handlers[index][y + count] = extra_handlers[x];
2991 /* This function will allocate and initialize an eh_nesting_info structure.
2992 It returns a pointer to the completed data structure. If there are
2993 no exception regions, a NULL value is returned. */
2995 init_eh_nesting_info ()
2997 int *nested_eh_region;
2998 int region_count = 0;
2999 rtx eh_note = NULL_RTX;
3000 eh_nesting_info *info;
3004 info = (eh_nesting_info *) malloc (sizeof (eh_nesting_info));
3005 info->region_index = (int *) malloc ((max_label_num () + 1) * sizeof (int));
3006 bzero ((char *) info->region_index, (max_label_num () + 1) * sizeof (int));
3008 nested_eh_region = (int *) alloca ((max_label_num () + 1) * sizeof (int));
3009 bzero ((char *) nested_eh_region, (max_label_num () + 1) * sizeof (int));
3011 /* Create the nested_eh_region list. If indexed with a block number, it
3012 returns the block number of the next outermost region, if any.
3013 We can count the number of regions and initialize the region_index
3014 vector at the same time. */
3015 for (insn = get_insns(); insn; insn = NEXT_INSN (insn))
3017 if (GET_CODE (insn) == NOTE)
3019 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG)
3021 int block = NOTE_BLOCK_NUMBER (insn);
3023 info->region_index[block] = region_count;
3025 nested_eh_region [block] =
3026 NOTE_BLOCK_NUMBER (XEXP (eh_note, 0));
3028 nested_eh_region [block] = 0;
3029 eh_note = gen_rtx_EXPR_LIST (VOIDmode, insn, eh_note);
3031 else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_END)
3032 eh_note = XEXP (eh_note, 1);
3036 /* If there are no regions, wrap it up now. */
3037 if (region_count == 0)
3039 free (info->region_index);
3045 info->handlers = (handler_info ***) malloc (region_count
3046 * sizeof (handler_info ***));
3047 info->num_handlers = (int *) malloc (region_count * sizeof (int));
3048 info->outer_index = (int *) malloc (region_count * sizeof (int));
3050 bzero ((char *) info->handlers, region_count * sizeof (rtx *));
3051 bzero ((char *) info->num_handlers, region_count * sizeof (int));
3052 bzero ((char *) info->outer_index, region_count * sizeof (int));
3054 /* Now initialize the handler lists for all exception blocks. */
3055 for (x = 0; x <= max_label_num (); x++)
3057 if (info->region_index[x] != 0)
3058 process_nestinfo (x, info, nested_eh_region);
3060 info->region_count = region_count;
3065 /* This function is used to retreive the vector of handlers which
3066 can be reached by a given insn in a given exception region.
3067 BLOCK is the exception block the insn is in.
3068 INFO is the eh_nesting_info structure.
3069 INSN is the (optional) insn within the block. If insn is not NULL_RTX,
3070 it may contain reg notes which modify its throwing behavior, and
3071 these will be obeyed. If NULL_RTX is passed, then we simply return the
3073 HANDLERS is the address of a pointer to a vector of handler_info pointers.
3074 Upon return, this will have the handlers which can be reached by block.
3075 This function returns the number of elements in the handlers vector. */
3077 reachable_handlers (block, info, insn, handlers)
3079 eh_nesting_info *info;
3081 handler_info ***handlers;
3089 index = info->region_index[block];
3091 if (insn && GET_CODE (insn) == CALL_INSN)
3093 /* RETHROWs specify a region number from which we are going to rethrow.
3094 This means we wont pass control to handlers in the specified
3095 region, but rather any region OUTSIDE the specified region.
3096 We accomplish this by setting block to the outer_index of the
3097 specified region. */
3098 rtx note = find_reg_note (insn, REG_EH_RETHROW, NULL_RTX);
3101 index = eh_region_from_symbol (XEXP (note, 0));
3102 index = info->region_index[index];
3104 index = info->outer_index[index];
3108 /* If there is no rethrow, we look for a REG_EH_REGION, and
3109 we'll throw from that block. A value of 0 or less
3110 indicates that this insn cannot throw. */
3111 note = find_reg_note (insn, REG_EH_REGION, NULL_RTX);
3114 int b = XINT (XEXP (note, 0), 0);
3118 index = info->region_index[b];
3122 /* If we reach this point, and index is 0, there is no throw. */
3126 *handlers = info->handlers[index];
3127 return info->num_handlers[index];
3131 /* This function will free all memory associated with the eh_nesting info. */
3134 free_eh_nesting_info (info)
3135 eh_nesting_info *info;
3140 if (info->region_index)
3141 free (info->region_index);
3142 if (info->num_handlers)
3143 free (info->num_handlers);
3144 if (info->outer_index)
3145 free (info->outer_index);
3148 for (x = 0; x < info->region_count; x++)
3149 if (info->handlers[x])
3150 free (info->handlers[x]);
3151 free (info->handlers);