1 /* Implements exception handling.
2 Copyright (C) 1989, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
3 1999, 2000 Free Software Foundation, Inc.
4 Contributed by Mike Stump <mrs@cygnus.com>.
6 This file is part of GNU CC.
8 GNU CC is free software; you can redistribute it and/or modify
9 it under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 2, or (at your option)
13 GNU CC is distributed in the hope that it will be useful,
14 but WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 GNU General Public License for more details.
18 You should have received a copy of the GNU General Public License
19 along with GNU CC; see the file COPYING. If not, write to
20 the Free Software Foundation, 59 Temple Place - Suite 330,
21 Boston, MA 02111-1307, USA. */
24 /* An exception is an event that can be signaled from within a
25 function. This event can then be "caught" or "trapped" by the
26 callers of this function. This potentially allows program flow to
27 be transferred to any arbitrary code associated with a function call
28 several levels up the stack.
30 The intended use for this mechanism is for signaling "exceptional
31 events" in an out-of-band fashion, hence its name. The C++ language
32 (and many other OO-styled or functional languages) practically
33 requires such a mechanism, as otherwise it becomes very difficult
34 or even impossible to signal failure conditions in complex
35 situations. The traditional C++ example is when an error occurs in
36 the process of constructing an object; without such a mechanism, it
37 is impossible to signal that the error occurs without adding global
38 state variables and error checks around every object construction.
40 The act of causing this event to occur is referred to as "throwing
41 an exception". (Alternate terms include "raising an exception" or
42 "signaling an exception".) The term "throw" is used because control
43 is returned to the callers of the function that is signaling the
44 exception, and thus there is the concept of "throwing" the
45 exception up the call stack.
47 There are two major codegen options for exception handling. The
48 flag -fsjlj-exceptions can be used to select the setjmp/longjmp
49 approach, which is the default. -fno-sjlj-exceptions can be used to
50 get the PC range table approach. While this is a compile time
51 flag, an entire application must be compiled with the same codegen
52 option. The first is a PC range table approach, the second is a
53 setjmp/longjmp based scheme. We will first discuss the PC range
54 table approach, after that, we will discuss the setjmp/longjmp
57 It is appropriate to speak of the "context of a throw". This
58 context refers to the address where the exception is thrown from,
59 and is used to determine which exception region will handle the
62 Regions of code within a function can be marked such that if it
63 contains the context of a throw, control will be passed to a
64 designated "exception handler". These areas are known as "exception
65 regions". Exception regions cannot overlap, but they can be nested
66 to any arbitrary depth. Also, exception regions cannot cross
69 Exception handlers can either be specified by the user (which we
70 will call a "user-defined handler") or generated by the compiler
71 (which we will designate as a "cleanup"). Cleanups are used to
72 perform tasks such as destruction of objects allocated on the
75 In the current implementation, cleanups are handled by allocating an
76 exception region for the area that the cleanup is designated for,
77 and the handler for the region performs the cleanup and then
78 rethrows the exception to the outer exception region. From the
79 standpoint of the current implementation, there is little
80 distinction made between a cleanup and a user-defined handler, and
81 the phrase "exception handler" can be used to refer to either one
82 equally well. (The section "Future Directions" below discusses how
85 Each object file that is compiled with exception handling contains
86 a static array of exception handlers named __EXCEPTION_TABLE__.
87 Each entry contains the starting and ending addresses of the
88 exception region, and the address of the handler designated for
91 If the target does not use the DWARF 2 frame unwind information, at
92 program startup each object file invokes a function named
93 __register_exceptions with the address of its local
94 __EXCEPTION_TABLE__. __register_exceptions is defined in libgcc2.c, and
95 is responsible for recording all of the exception regions into one list
96 (which is kept in a static variable named exception_table_list).
98 On targets that support crtstuff.c, the unwind information
99 is stored in a section named .eh_frame and the information for the
100 entire shared object or program is registered with a call to
101 __register_frame_info. On other targets, the information for each
102 translation unit is registered from the file generated by collect2.
103 __register_frame_info is defined in frame.c, and is responsible for
104 recording all of the unwind regions into one list (which is kept in a
105 static variable named unwind_table_list).
107 The function __throw is actually responsible for doing the
108 throw. On machines that have unwind info support, __throw is generated
109 by code in libgcc2.c, otherwise __throw is generated on a
110 per-object-file basis for each source file compiled with
111 -fexceptions by the C++ frontend. Before __throw is invoked,
112 the current context of the throw needs to be placed in the global
115 __throw attempts to find the appropriate exception handler for the
116 PC value stored in __eh_pc by calling __find_first_exception_table_match
117 (which is defined in libgcc2.c). If __find_first_exception_table_match
118 finds a relevant handler, __throw transfers control directly to it.
120 If a handler for the context being thrown from can't be found, __throw
121 walks (see Walking the stack below) the stack up the dynamic call chain to
122 continue searching for an appropriate exception handler based upon the
123 caller of the function it last sought a exception handler for. It stops
124 then either an exception handler is found, or when the top of the
125 call chain is reached.
127 If no handler is found, an external library function named
128 __terminate is called. If a handler is found, then we restart
129 our search for a handler at the end of the call chain, and repeat
130 the search process, but instead of just walking up the call chain,
131 we unwind the call chain as we walk up it.
133 Internal implementation details:
135 To associate a user-defined handler with a block of statements, the
136 function expand_start_try_stmts is used to mark the start of the
137 block of statements with which the handler is to be associated
138 (which is known as a "try block"). All statements that appear
139 afterwards will be associated with the try block.
141 A call to expand_start_all_catch marks the end of the try block,
142 and also marks the start of the "catch block" (the user-defined
143 handler) associated with the try block.
145 This user-defined handler will be invoked for *every* exception
146 thrown with the context of the try block. It is up to the handler
147 to decide whether or not it wishes to handle any given exception,
148 as there is currently no mechanism in this implementation for doing
149 this. (There are plans for conditionally processing an exception
150 based on its "type", which will provide a language-independent
153 If the handler chooses not to process the exception (perhaps by
154 looking at an "exception type" or some other additional data
155 supplied with the exception), it can fall through to the end of the
156 handler. expand_end_all_catch and expand_leftover_cleanups
157 add additional code to the end of each handler to take care of
158 rethrowing to the outer exception handler.
160 The handler also has the option to continue with "normal flow of
161 code", or in other words to resume executing at the statement
162 immediately after the end of the exception region. The variable
163 caught_return_label_stack contains a stack of labels, and jumping
164 to the topmost entry's label via expand_goto will resume normal
165 flow to the statement immediately after the end of the exception
166 region. If the handler falls through to the end, the exception will
167 be rethrown to the outer exception region.
169 The instructions for the catch block are kept as a separate
170 sequence, and will be emitted at the end of the function along with
171 the handlers specified via expand_eh_region_end. The end of the
172 catch block is marked with expand_end_all_catch.
174 Any data associated with the exception must currently be handled by
175 some external mechanism maintained in the frontend. For example,
176 the C++ exception mechanism passes an arbitrary value along with
177 the exception, and this is handled in the C++ frontend by using a
178 global variable to hold the value. (This will be changing in the
181 The mechanism in C++ for handling data associated with the
182 exception is clearly not thread-safe. For a thread-based
183 environment, another mechanism must be used (possibly using a
184 per-thread allocation mechanism if the size of the area that needs
185 to be allocated isn't known at compile time.)
187 Internally-generated exception regions (cleanups) are marked by
188 calling expand_eh_region_start to mark the start of the region,
189 and expand_eh_region_end (handler) is used to both designate the
190 end of the region and to associate a specified handler/cleanup with
191 the region. The rtl code in HANDLER will be invoked whenever an
192 exception occurs in the region between the calls to
193 expand_eh_region_start and expand_eh_region_end. After HANDLER is
194 executed, additional code is emitted to handle rethrowing the
195 exception to the outer exception handler. The code for HANDLER will
196 be emitted at the end of the function.
198 TARGET_EXPRs can also be used to designate exception regions. A
199 TARGET_EXPR gives an unwind-protect style interface commonly used
200 in functional languages such as LISP. The associated expression is
201 evaluated, and whether or not it (or any of the functions that it
202 calls) throws an exception, the protect expression is always
203 invoked. This implementation takes care of the details of
204 associating an exception table entry with the expression and
205 generating the necessary code (it actually emits the protect
206 expression twice, once for normal flow and once for the exception
207 case). As for the other handlers, the code for the exception case
208 will be emitted at the end of the function.
210 Cleanups can also be specified by using add_partial_entry (handler)
211 and end_protect_partials. add_partial_entry creates the start of
212 a new exception region; HANDLER will be invoked if an exception is
213 thrown with the context of the region between the calls to
214 add_partial_entry and end_protect_partials. end_protect_partials is
215 used to mark the end of these regions. add_partial_entry can be
216 called as many times as needed before calling end_protect_partials.
217 However, end_protect_partials should only be invoked once for each
218 group of calls to add_partial_entry as the entries are queued
219 and all of the outstanding entries are processed simultaneously
220 when end_protect_partials is invoked. Similarly to the other
221 handlers, the code for HANDLER will be emitted at the end of the
224 The generated RTL for an exception region includes
225 NOTE_INSN_EH_REGION_BEG and NOTE_INSN_EH_REGION_END notes that mark
226 the start and end of the exception region. A unique label is also
227 generated at the start of the exception region, which is available
228 by looking at the ehstack variable. The topmost entry corresponds
229 to the current region.
231 In the current implementation, an exception can only be thrown from
232 a function call (since the mechanism used to actually throw an
233 exception involves calling __throw). If an exception region is
234 created but no function calls occur within that region, the region
235 can be safely optimized away (along with its exception handlers)
236 since no exceptions can ever be caught in that region. This
237 optimization is performed unless -fasynchronous-exceptions is
238 given. If the user wishes to throw from a signal handler, or other
239 asynchronous place, -fasynchronous-exceptions should be used when
240 compiling for maximally correct code, at the cost of additional
241 exception regions. Using -fasynchronous-exceptions only produces
242 code that is reasonably safe in such situations, but a correct
243 program cannot rely upon this working. It can be used in failsafe
244 code, where trying to continue on, and proceeding with potentially
245 incorrect results is better than halting the program.
250 The stack is walked by starting with a pointer to the current
251 frame, and finding the pointer to the callers frame. The unwind info
252 tells __throw how to find it.
256 When we use the term unwinding the stack, we mean undoing the
257 effects of the function prologue in a controlled fashion so that we
258 still have the flow of control. Otherwise, we could just return
259 (jump to the normal end of function epilogue).
261 This is done in __throw in libgcc2.c when we know that a handler exists
262 in a frame higher up the call stack than its immediate caller.
264 To unwind, we find the unwind data associated with the frame, if any.
265 If we don't find any, we call the library routine __terminate. If we do
266 find it, we use the information to copy the saved register values from
267 that frame into the register save area in the frame for __throw, return
268 into a stub which updates the stack pointer, and jump to the handler.
269 The normal function epilogue for __throw handles restoring the saved
270 values into registers.
272 When unwinding, we use this method if we know it will
273 work (if DWARF2_UNWIND_INFO is defined). Otherwise, we know that
274 an inline unwinder will have been emitted for any function that
275 __unwind_function cannot unwind. The inline unwinder appears as a
276 normal exception handler for the entire function, for any function
277 that we know cannot be unwound by __unwind_function. We inform the
278 compiler of whether a function can be unwound with
279 __unwind_function by having DOESNT_NEED_UNWINDER evaluate to true
280 when the unwinder isn't needed. __unwind_function is used as an
281 action of last resort. If no other method can be used for
282 unwinding, __unwind_function is used. If it cannot unwind, it
283 should call __terminate.
285 By default, if the target-specific backend doesn't supply a definition
286 for __unwind_function and doesn't support DWARF2_UNWIND_INFO, inlined
287 unwinders will be used instead. The main tradeoff here is in text space
288 utilization. Obviously, if inline unwinders have to be generated
289 repeatedly, this uses much more space than if a single routine is used.
291 However, it is simply not possible on some platforms to write a
292 generalized routine for doing stack unwinding without having some
293 form of additional data associated with each function. The current
294 implementation can encode this data in the form of additional
295 machine instructions or as static data in tabular form. The later
296 is called the unwind data.
298 The backend macro DOESNT_NEED_UNWINDER is used to conditionalize whether
299 or not per-function unwinders are needed. If DOESNT_NEED_UNWINDER is
300 defined and has a non-zero value, a per-function unwinder is not emitted
301 for the current function. If the static unwind data is supported, then
302 a per-function unwinder is not emitted.
304 On some platforms it is possible that neither __unwind_function
305 nor inlined unwinders are available. For these platforms it is not
306 possible to throw through a function call, and abort will be
307 invoked instead of performing the throw.
309 The reason the unwind data may be needed is that on some platforms
310 the order and types of data stored on the stack can vary depending
311 on the type of function, its arguments and returned values, and the
312 compilation options used (optimization versus non-optimization,
313 -fomit-frame-pointer, processor variations, etc).
315 Unfortunately, this also means that throwing through functions that
316 aren't compiled with exception handling support will still not be
317 possible on some platforms. This problem is currently being
318 investigated, but no solutions have been found that do not imply
319 some unacceptable performance penalties.
323 Currently __throw makes no differentiation between cleanups and
324 user-defined exception regions. While this makes the implementation
325 simple, it also implies that it is impossible to determine if a
326 user-defined exception handler exists for a given exception without
327 completely unwinding the stack in the process. This is undesirable
328 from the standpoint of debugging, as ideally it would be possible
329 to trap unhandled exceptions in the debugger before the process of
330 unwinding has even started.
332 This problem can be solved by marking user-defined handlers in a
333 special way (probably by adding additional bits to exception_table_list).
334 A two-pass scheme could then be used by __throw to iterate
335 through the table. The first pass would search for a relevant
336 user-defined handler for the current context of the throw, and if
337 one is found, the second pass would then invoke all needed cleanups
338 before jumping to the user-defined handler.
340 Many languages (including C++ and Ada) make execution of a
341 user-defined handler conditional on the "type" of the exception
342 thrown. (The type of the exception is actually the type of the data
343 that is thrown with the exception.) It will thus be necessary for
344 __throw to be able to determine if a given user-defined
345 exception handler will actually be executed, given the type of
348 One scheme is to add additional information to exception_table_list
349 as to the types of exceptions accepted by each handler. __throw
350 can do the type comparisons and then determine if the handler is
351 actually going to be executed.
353 There is currently no significant level of debugging support
354 available, other than to place a breakpoint on __throw. While
355 this is sufficient in most cases, it would be helpful to be able to
356 know where a given exception was going to be thrown to before it is
357 actually thrown, and to be able to choose between stopping before
358 every exception region (including cleanups), or just user-defined
359 exception regions. This should be possible to do in the two-pass
360 scheme by adding additional labels to __throw for appropriate
361 breakpoints, and additional debugger commands could be added to
362 query various state variables to determine what actions are to be
365 Another major problem that is being worked on is the issue with stack
366 unwinding on various platforms. Currently the only platforms that have
367 support for the generation of a generic unwinder are the SPARC and MIPS.
368 All other ports require per-function unwinders, which produce large
369 amounts of code bloat.
371 For setjmp/longjmp based exception handling, some of the details
372 are as above, but there are some additional details. This section
373 discusses the details.
375 We don't use NOTE_INSN_EH_REGION_{BEG,END} pairs. We don't
376 optimize EH regions yet. We don't have to worry about machine
377 specific issues with unwinding the stack, as we rely upon longjmp
378 for all the machine specific details. There is no variable context
379 of a throw, just the one implied by the dynamic handler stack
380 pointed to by the dynamic handler chain. There is no exception
381 table, and no calls to __register_exceptions. __sjthrow is used
382 instead of __throw, and it works by using the dynamic handler
383 chain, and longjmp. -fasynchronous-exceptions has no effect, as
384 the elimination of trivial exception regions is not yet performed.
386 A frontend can set protect_cleanup_actions_with_terminate when all
387 the cleanup actions should be protected with an EH region that
388 calls terminate when an unhandled exception is throw. C++ does
389 this, Ada does not. */
393 #include "defaults.h"
394 #include "eh-common.h"
400 #include "function.h"
401 #include "insn-flags.h"
403 #include "insn-codes.h"
405 #include "hard-reg-set.h"
406 #include "insn-config.h"
415 /* One to use setjmp/longjmp method of generating code for exception
418 int exceptions_via_longjmp = 2;
420 /* One to enable asynchronous exception support. */
422 int asynchronous_exceptions = 0;
424 /* One to protect cleanup actions with a handler that calls
425 __terminate, zero otherwise. */
427 int protect_cleanup_actions_with_terminate;
429 /* A list of labels used for exception handlers. Created by
430 find_exception_handler_labels for the optimization passes. */
432 rtx exception_handler_labels;
434 /* Keeps track of the label used as the context of a throw to rethrow an
435 exception to the outer exception region. */
437 struct label_node *outer_context_label_stack = NULL;
439 /* Pseudos used to hold exception return data in the interim between
440 __builtin_eh_return and the end of the function. */
442 static rtx eh_return_context;
443 static rtx eh_return_stack_adjust;
444 static rtx eh_return_handler;
446 /* This is used for targets which can call rethrow with an offset instead
447 of an address. This is subtracted from the rethrow label we are
450 static rtx first_rethrow_symbol = NULL_RTX;
451 static rtx final_rethrow = NULL_RTX;
452 static rtx last_rethrow_symbol = NULL_RTX;
455 /* Prototypes for local functions. */
457 static void push_eh_entry PARAMS ((struct eh_stack *));
458 static struct eh_entry * pop_eh_entry PARAMS ((struct eh_stack *));
459 static void enqueue_eh_entry PARAMS ((struct eh_queue *, struct eh_entry *));
460 static struct eh_entry * dequeue_eh_entry PARAMS ((struct eh_queue *));
461 static rtx call_get_eh_context PARAMS ((void));
462 static void start_dynamic_cleanup PARAMS ((tree, tree));
463 static void start_dynamic_handler PARAMS ((void));
464 static void expand_rethrow PARAMS ((rtx));
465 static void output_exception_table_entry PARAMS ((FILE *, int));
466 static int can_throw PARAMS ((rtx));
467 static rtx scan_region PARAMS ((rtx, int, int *));
468 static void eh_regs PARAMS ((rtx *, rtx *, rtx *, int));
469 static void set_insn_eh_region PARAMS ((rtx *, int));
470 #ifdef DONT_USE_BUILTIN_SETJMP
471 static void jumpif_rtx PARAMS ((rtx, rtx));
473 static void mark_eh_node PARAMS ((struct eh_node *));
474 static void mark_eh_stack PARAMS ((struct eh_stack *));
475 static void mark_eh_queue PARAMS ((struct eh_queue *));
476 static void mark_tree_label_node PARAMS ((struct label_node *));
477 static void mark_func_eh_entry PARAMS ((void *));
478 static rtx create_rethrow_ref PARAMS ((int));
479 static void push_entry PARAMS ((struct eh_stack *, struct eh_entry*));
480 static void receive_exception_label PARAMS ((rtx));
481 static int new_eh_region_entry PARAMS ((int, rtx));
482 static int find_func_region PARAMS ((int));
483 static int find_func_region_from_symbol PARAMS ((rtx));
484 static void clear_function_eh_region PARAMS ((void));
485 static void process_nestinfo PARAMS ((int, eh_nesting_info *, int *));
487 rtx expand_builtin_return_addr PARAMS ((enum built_in_function, int, rtx));
488 static void emit_cleanup_handler PARAMS ((struct eh_entry *));
489 static int eh_region_from_symbol PARAMS ((rtx));
492 /* Various support routines to manipulate the various data structures
493 used by the exception handling code. */
495 extern struct obstack permanent_obstack;
497 /* Generate a SYMBOL_REF for rethrow to use */
500 create_rethrow_ref (region_num)
507 push_obstacks_nochange ();
508 end_temporary_allocation ();
510 ASM_GENERATE_INTERNAL_LABEL (buf, "LRTH", region_num);
511 ptr = ggc_alloc_string (buf, -1);
512 def = gen_rtx_SYMBOL_REF (Pmode, ptr);
513 SYMBOL_REF_NEED_ADJUST (def) = 1;
519 /* Push a label entry onto the given STACK. */
522 push_label_entry (stack, rlabel, tlabel)
523 struct label_node **stack;
527 struct label_node *newnode
528 = (struct label_node *) xmalloc (sizeof (struct label_node));
531 newnode->u.rlabel = rlabel;
533 newnode->u.tlabel = tlabel;
534 newnode->chain = *stack;
538 /* Pop a label entry from the given STACK. */
541 pop_label_entry (stack)
542 struct label_node **stack;
545 struct label_node *tempnode;
551 label = tempnode->u.rlabel;
552 *stack = (*stack)->chain;
558 /* Return the top element of the given STACK. */
561 top_label_entry (stack)
562 struct label_node **stack;
567 return (*stack)->u.tlabel;
570 /* Get an exception label. */
573 gen_exception_label ()
576 lab = gen_label_rtx ();
580 /* Push a new eh_node entry onto STACK. */
583 push_eh_entry (stack)
584 struct eh_stack *stack;
586 struct eh_node *node = (struct eh_node *) xmalloc (sizeof (struct eh_node));
587 struct eh_entry *entry = (struct eh_entry *) xmalloc (sizeof (struct eh_entry));
589 rtx rlab = gen_exception_label ();
590 entry->finalization = NULL_TREE;
591 entry->label_used = 0;
592 entry->exception_handler_label = rlab;
593 entry->false_label = NULL_RTX;
594 if (! flag_new_exceptions)
595 entry->outer_context = gen_label_rtx ();
597 entry->outer_context = create_rethrow_ref (CODE_LABEL_NUMBER (rlab));
598 entry->rethrow_label = entry->outer_context;
599 entry->goto_entry_p = 0;
602 node->chain = stack->top;
606 /* Push an existing entry onto a stack. */
609 push_entry (stack, entry)
610 struct eh_stack *stack;
611 struct eh_entry *entry;
613 struct eh_node *node = (struct eh_node *) xmalloc (sizeof (struct eh_node));
615 node->chain = stack->top;
619 /* Pop an entry from the given STACK. */
621 static struct eh_entry *
623 struct eh_stack *stack;
625 struct eh_node *tempnode;
626 struct eh_entry *tempentry;
628 tempnode = stack->top;
629 tempentry = tempnode->entry;
630 stack->top = stack->top->chain;
636 /* Enqueue an ENTRY onto the given QUEUE. */
639 enqueue_eh_entry (queue, entry)
640 struct eh_queue *queue;
641 struct eh_entry *entry;
643 struct eh_node *node = (struct eh_node *) xmalloc (sizeof (struct eh_node));
648 if (queue->head == NULL)
651 queue->tail->chain = node;
655 /* Dequeue an entry from the given QUEUE. */
657 static struct eh_entry *
658 dequeue_eh_entry (queue)
659 struct eh_queue *queue;
661 struct eh_node *tempnode;
662 struct eh_entry *tempentry;
664 if (queue->head == NULL)
667 tempnode = queue->head;
668 queue->head = queue->head->chain;
670 tempentry = tempnode->entry;
677 receive_exception_label (handler_label)
680 emit_label (handler_label);
682 #ifdef HAVE_exception_receiver
683 if (! exceptions_via_longjmp)
684 if (HAVE_exception_receiver)
685 emit_insn (gen_exception_receiver ());
688 #ifdef HAVE_nonlocal_goto_receiver
689 if (! exceptions_via_longjmp)
690 if (HAVE_nonlocal_goto_receiver)
691 emit_insn (gen_nonlocal_goto_receiver ());
698 int range_number; /* EH region number from EH NOTE insn's. */
699 rtx rethrow_label; /* Label for rethrow. */
700 int rethrow_ref; /* Is rethrow_label referenced? */
701 struct handler_info *handlers;
705 /* table of function eh regions */
706 static struct func_eh_entry *function_eh_regions = NULL;
707 static int num_func_eh_entries = 0;
708 static int current_func_eh_entry = 0;
710 #define SIZE_FUNC_EH(X) (sizeof (struct func_eh_entry) * X)
712 /* Add a new eh_entry for this function. The number returned is an
713 number which uniquely identifies this exception range. */
716 new_eh_region_entry (note_eh_region, rethrow)
720 if (current_func_eh_entry == num_func_eh_entries)
722 if (num_func_eh_entries == 0)
724 function_eh_regions =
725 (struct func_eh_entry *) xmalloc (SIZE_FUNC_EH (50));
726 num_func_eh_entries = 50;
730 num_func_eh_entries = num_func_eh_entries * 3 / 2;
731 function_eh_regions = (struct func_eh_entry *)
732 xrealloc (function_eh_regions, SIZE_FUNC_EH (num_func_eh_entries));
735 function_eh_regions[current_func_eh_entry].range_number = note_eh_region;
736 if (rethrow == NULL_RTX)
737 function_eh_regions[current_func_eh_entry].rethrow_label =
738 create_rethrow_ref (note_eh_region);
740 function_eh_regions[current_func_eh_entry].rethrow_label = rethrow;
741 function_eh_regions[current_func_eh_entry].handlers = NULL;
743 return current_func_eh_entry++;
746 /* Add new handler information to an exception range. The first parameter
747 specifies the range number (returned from new_eh_entry()). The second
748 parameter specifies the handler. By default the handler is inserted at
749 the end of the list. A handler list may contain only ONE NULL_TREE
750 typeinfo entry. Regardless where it is positioned, a NULL_TREE entry
751 is always output as the LAST handler in the exception table for a region. */
754 add_new_handler (region, newhandler)
756 struct handler_info *newhandler;
758 struct handler_info *last;
760 /* If find_func_region returns -1, callers might attempt to pass us
761 this region number. If that happens, something has gone wrong;
762 -1 is never a valid region. */
766 newhandler->next = NULL;
767 last = function_eh_regions[region].handlers;
769 function_eh_regions[region].handlers = newhandler;
772 for ( ; ; last = last->next)
774 if (last->type_info == CATCH_ALL_TYPE)
775 pedwarn ("additional handler after ...");
776 if (last->next == NULL)
779 last->next = newhandler;
783 /* Remove a handler label. The handler label is being deleted, so all
784 regions which reference this handler should have it removed from their
785 list of possible handlers. Any region which has the final handler
786 removed can be deleted. */
788 void remove_handler (removing_label)
791 struct handler_info *handler, *last;
793 for (x = 0 ; x < current_func_eh_entry; ++x)
796 handler = function_eh_regions[x].handlers;
797 for ( ; handler; last = handler, handler = handler->next)
798 if (handler->handler_label == removing_label)
802 last->next = handler->next;
806 function_eh_regions[x].handlers = handler->next;
811 /* This function will return a malloc'd pointer to an array of
812 void pointer representing the runtime match values that
813 currently exist in all regions. */
816 find_all_handler_type_matches (array)
819 struct handler_info *handler, *last;
828 if (!doing_eh (0) || ! flag_new_exceptions)
832 ptr = (void **) xmalloc (max_ptr * sizeof (void *));
834 for (x = 0 ; x < current_func_eh_entry; x++)
837 handler = function_eh_regions[x].handlers;
838 for ( ; handler; last = handler, handler = handler->next)
840 val = handler->type_info;
841 if (val != NULL && val != CATCH_ALL_TYPE)
843 /* See if this match value has already been found. */
844 for (y = 0; y < n_ptr; y++)
848 /* If we break early, we already found this value. */
852 /* Do we need to allocate more space? */
853 if (n_ptr >= max_ptr)
855 max_ptr += max_ptr / 2;
856 ptr = (void **) xrealloc (ptr, max_ptr * sizeof (void *));
873 /* Create a new handler structure initialized with the handler label and
874 typeinfo fields passed in. */
876 struct handler_info *
877 get_new_handler (handler, typeinfo)
881 struct handler_info* ptr;
882 ptr = (struct handler_info *) xmalloc (sizeof (struct handler_info));
883 ptr->handler_label = handler;
884 ptr->handler_number = CODE_LABEL_NUMBER (handler);
885 ptr->type_info = typeinfo;
893 /* Find the index in function_eh_regions associated with a NOTE region. If
894 the region cannot be found, a -1 is returned. */
897 find_func_region (insn_region)
901 for (x = 0; x < current_func_eh_entry; x++)
902 if (function_eh_regions[x].range_number == insn_region)
908 /* Get a pointer to the first handler in an exception region's list. */
910 struct handler_info *
911 get_first_handler (region)
914 int r = find_func_region (region);
917 return function_eh_regions[r].handlers;
920 /* Clean out the function_eh_region table and free all memory */
923 clear_function_eh_region ()
926 struct handler_info *ptr, *next;
927 for (x = 0; x < current_func_eh_entry; x++)
928 for (ptr = function_eh_regions[x].handlers; ptr != NULL; ptr = next)
933 free (function_eh_regions);
934 num_func_eh_entries = 0;
935 current_func_eh_entry = 0;
938 /* Make a duplicate of an exception region by copying all the handlers
939 for an exception region. Return the new handler index. The final
940 parameter is a routine which maps old labels to new ones. */
943 duplicate_eh_handlers (old_note_eh_region, new_note_eh_region, map)
944 int old_note_eh_region, new_note_eh_region;
945 rtx (*map) PARAMS ((rtx));
947 struct handler_info *ptr, *new_ptr;
948 int new_region, region;
950 region = find_func_region (old_note_eh_region);
952 fatal ("Cannot duplicate non-existant exception region.");
954 /* duplicate_eh_handlers may have been called during a symbol remap. */
955 new_region = find_func_region (new_note_eh_region);
956 if (new_region != -1)
959 new_region = new_eh_region_entry (new_note_eh_region, NULL_RTX);
961 ptr = function_eh_regions[region].handlers;
963 for ( ; ptr; ptr = ptr->next)
965 new_ptr = get_new_handler (map (ptr->handler_label), ptr->type_info);
966 add_new_handler (new_region, new_ptr);
973 /* Given a rethrow symbol, find the EH region number this is for. */
976 eh_region_from_symbol (sym)
980 if (sym == last_rethrow_symbol)
982 for (x = 0; x < current_func_eh_entry; x++)
983 if (function_eh_regions[x].rethrow_label == sym)
984 return function_eh_regions[x].range_number;
988 /* Like find_func_region, but using the rethrow symbol for the region
989 rather than the region number itself. */
992 find_func_region_from_symbol (sym)
995 return find_func_region (eh_region_from_symbol (sym));
998 /* When inlining/unrolling, we have to map the symbols passed to
999 __rethrow as well. This performs the remap. If a symbol isn't foiund,
1000 the original one is returned. This is not an efficient routine,
1001 so don't call it on everything!! */
1004 rethrow_symbol_map (sym, map)
1006 rtx (*map) PARAMS ((rtx));
1010 if (! flag_new_exceptions)
1013 for (x = 0; x < current_func_eh_entry; x++)
1014 if (function_eh_regions[x].rethrow_label == sym)
1016 /* We've found the original region, now lets determine which region
1017 this now maps to. */
1018 rtx l1 = function_eh_regions[x].handlers->handler_label;
1020 y = CODE_LABEL_NUMBER (l2); /* This is the new region number */
1021 x = find_func_region (y); /* Get the new permanent region */
1022 if (x == -1) /* Hmm, Doesn't exist yet */
1024 x = duplicate_eh_handlers (CODE_LABEL_NUMBER (l1), y, map);
1025 /* Since we're mapping it, it must be used. */
1026 function_eh_regions[x].rethrow_ref = 1;
1028 return function_eh_regions[x].rethrow_label;
1033 /* Returns nonzero if the rethrow label for REGION is referenced
1034 somewhere (i.e. we rethrow out of REGION or some other region
1035 masquerading as REGION). */
1038 rethrow_used (region)
1041 if (flag_new_exceptions)
1043 int ret = function_eh_regions[find_func_region (region)].rethrow_ref;
1050 /* Routine to see if exception handling is turned on.
1051 DO_WARN is non-zero if we want to inform the user that exception
1052 handling is turned off.
1054 This is used to ensure that -fexceptions has been specified if the
1055 compiler tries to use any exception-specific functions. */
1061 if (! flag_exceptions)
1063 static int warned = 0;
1064 if (! warned && do_warn)
1066 error ("exception handling disabled, use -fexceptions to enable");
1074 /* Given a return address in ADDR, determine the address we should use
1075 to find the corresponding EH region. */
1078 eh_outer_context (addr)
1081 /* First mask out any unwanted bits. */
1082 #ifdef MASK_RETURN_ADDR
1083 expand_and (addr, MASK_RETURN_ADDR, addr);
1086 /* Then adjust to find the real return address. */
1087 #if defined (RETURN_ADDR_OFFSET)
1088 addr = plus_constant (addr, RETURN_ADDR_OFFSET);
1094 /* Start a new exception region for a region of code that has a
1095 cleanup action and push the HANDLER for the region onto
1096 protect_list. All of the regions created with add_partial_entry
1097 will be ended when end_protect_partials is invoked. */
1100 add_partial_entry (handler)
1103 expand_eh_region_start ();
1105 /* Make sure the entry is on the correct obstack. */
1106 push_obstacks_nochange ();
1107 resume_temporary_allocation ();
1109 /* Because this is a cleanup action, we may have to protect the handler
1110 with __terminate. */
1111 handler = protect_with_terminate (handler);
1113 /* For backwards compatibility, we allow callers to omit calls to
1114 begin_protect_partials for the outermost region. So, we must
1115 explicitly do so here. */
1117 begin_protect_partials ();
1119 /* Add this entry to the front of the list. */
1120 TREE_VALUE (protect_list)
1121 = tree_cons (NULL_TREE, handler, TREE_VALUE (protect_list));
1125 /* Emit code to get EH context to current function. */
1128 call_get_eh_context ()
1133 if (fn == NULL_TREE)
1136 fn = get_identifier ("__get_eh_context");
1137 push_obstacks_nochange ();
1138 end_temporary_allocation ();
1139 fntype = build_pointer_type (build_pointer_type
1140 (build_pointer_type (void_type_node)));
1141 fntype = build_function_type (fntype, NULL_TREE);
1142 fn = build_decl (FUNCTION_DECL, fn, fntype);
1143 DECL_EXTERNAL (fn) = 1;
1144 TREE_PUBLIC (fn) = 1;
1145 DECL_ARTIFICIAL (fn) = 1;
1146 TREE_READONLY (fn) = 1;
1147 make_decl_rtl (fn, NULL_PTR, 1);
1148 assemble_external (fn);
1151 ggc_add_tree_root (&fn, 1);
1154 expr = build1 (ADDR_EXPR, build_pointer_type (TREE_TYPE (fn)), fn);
1155 expr = build (CALL_EXPR, TREE_TYPE (TREE_TYPE (fn)),
1156 expr, NULL_TREE, NULL_TREE);
1157 TREE_SIDE_EFFECTS (expr) = 1;
1159 return copy_to_reg (expand_expr (expr, NULL_RTX, VOIDmode, 0));
1162 /* Get a reference to the EH context.
1163 We will only generate a register for the current function EH context here,
1164 and emit a USE insn to mark that this is a EH context register.
1166 Later, emit_eh_context will emit needed call to __get_eh_context
1167 in libgcc2, and copy the value to the register we have generated. */
1172 if (current_function_ehc == 0)
1176 current_function_ehc = gen_reg_rtx (Pmode);
1178 insn = gen_rtx_USE (GET_MODE (current_function_ehc),
1179 current_function_ehc);
1180 insn = emit_insn_before (insn, get_first_nonparm_insn ());
1183 = gen_rtx_EXPR_LIST (REG_EH_CONTEXT, current_function_ehc,
1186 return current_function_ehc;
1189 /* Get a reference to the dynamic handler chain. It points to the
1190 pointer to the next element in the dynamic handler chain. It ends
1191 when there are no more elements in the dynamic handler chain, when
1192 the value is &top_elt from libgcc2.c. Immediately after the
1193 pointer, is an area suitable for setjmp/longjmp when
1194 DONT_USE_BUILTIN_SETJMP is defined, and an area suitable for
1195 __builtin_setjmp/__builtin_longjmp when DONT_USE_BUILTIN_SETJMP
1199 get_dynamic_handler_chain ()
1201 rtx ehc, dhc, result;
1203 ehc = get_eh_context ();
1205 /* This is the offset of dynamic_handler_chain in the eh_context struct
1206 declared in eh-common.h. If its location is change, change this offset */
1207 dhc = plus_constant (ehc, POINTER_SIZE / BITS_PER_UNIT);
1209 result = copy_to_reg (dhc);
1211 /* We don't want a copy of the dcc, but rather, the single dcc. */
1212 return gen_rtx_MEM (Pmode, result);
1215 /* Get a reference to the dynamic cleanup chain. It points to the
1216 pointer to the next element in the dynamic cleanup chain.
1217 Immediately after the pointer, are two Pmode variables, one for a
1218 pointer to a function that performs the cleanup action, and the
1219 second, the argument to pass to that function. */
1222 get_dynamic_cleanup_chain ()
1224 rtx dhc, dcc, result;
1226 dhc = get_dynamic_handler_chain ();
1227 dcc = plus_constant (dhc, POINTER_SIZE / BITS_PER_UNIT);
1229 result = copy_to_reg (dcc);
1231 /* We don't want a copy of the dcc, but rather, the single dcc. */
1232 return gen_rtx_MEM (Pmode, result);
1235 #ifdef DONT_USE_BUILTIN_SETJMP
1236 /* Generate code to evaluate X and jump to LABEL if the value is nonzero.
1237 LABEL is an rtx of code CODE_LABEL, in this function. */
1240 jumpif_rtx (x, label)
1244 jumpif (make_tree (type_for_mode (GET_MODE (x), 0), x), label);
1248 /* Start a dynamic cleanup on the EH runtime dynamic cleanup stack.
1249 We just need to create an element for the cleanup list, and push it
1252 A dynamic cleanup is a cleanup action implied by the presence of an
1253 element on the EH runtime dynamic cleanup stack that is to be
1254 performed when an exception is thrown. The cleanup action is
1255 performed by __sjthrow when an exception is thrown. Only certain
1256 actions can be optimized into dynamic cleanup actions. For the
1257 restrictions on what actions can be performed using this routine,
1258 see expand_eh_region_start_tree. */
1261 start_dynamic_cleanup (func, arg)
1266 rtx new_func, new_arg;
1270 /* We allocate enough room for a pointer to the function, and
1274 /* XXX, FIXME: The stack space allocated this way is too long lived,
1275 but there is no allocation routine that allocates at the level of
1276 the last binding contour. */
1277 buf = assign_stack_local (BLKmode,
1278 GET_MODE_SIZE (Pmode)*(size+1),
1281 buf = change_address (buf, Pmode, NULL_RTX);
1283 /* Store dcc into the first word of the newly allocated buffer. */
1285 dcc = get_dynamic_cleanup_chain ();
1286 emit_move_insn (buf, dcc);
1288 /* Store func and arg into the cleanup list element. */
1290 new_func = gen_rtx_MEM (Pmode, plus_constant (XEXP (buf, 0),
1291 GET_MODE_SIZE (Pmode)));
1292 new_arg = gen_rtx_MEM (Pmode, plus_constant (XEXP (buf, 0),
1293 GET_MODE_SIZE (Pmode)*2));
1294 x = expand_expr (func, new_func, Pmode, 0);
1296 emit_move_insn (new_func, x);
1298 x = expand_expr (arg, new_arg, Pmode, 0);
1300 emit_move_insn (new_arg, x);
1302 /* Update the cleanup chain. */
1304 x = force_operand (XEXP (buf, 0), dcc);
1306 emit_move_insn (dcc, x);
1309 /* Emit RTL to start a dynamic handler on the EH runtime dynamic
1310 handler stack. This should only be used by expand_eh_region_start
1311 or expand_eh_region_start_tree. */
1314 start_dynamic_handler ()
1320 #ifndef DONT_USE_BUILTIN_SETJMP
1321 /* The number of Pmode words for the setjmp buffer, when using the
1322 builtin setjmp/longjmp, see expand_builtin, case BUILT_IN_LONGJMP. */
1323 /* We use 2 words here before calling expand_builtin_setjmp.
1324 expand_builtin_setjmp uses 2 words, and then calls emit_stack_save.
1325 emit_stack_save needs space of size STACK_SAVEAREA_MODE (SAVE_NONLOCAL).
1326 Subtract one, because the assign_stack_local call below adds 1. */
1327 size = (2 + 2 + (GET_MODE_SIZE (STACK_SAVEAREA_MODE (SAVE_NONLOCAL))
1328 / GET_MODE_SIZE (Pmode))
1332 size = JMP_BUF_SIZE;
1334 /* Should be large enough for most systems, if it is not,
1335 JMP_BUF_SIZE should be defined with the proper value. It will
1336 also tend to be larger than necessary for most systems, a more
1337 optimal port will define JMP_BUF_SIZE. */
1338 size = FIRST_PSEUDO_REGISTER+2;
1341 /* XXX, FIXME: The stack space allocated this way is too long lived,
1342 but there is no allocation routine that allocates at the level of
1343 the last binding contour. */
1344 arg = assign_stack_local (BLKmode,
1345 GET_MODE_SIZE (Pmode)*(size+1),
1348 arg = change_address (arg, Pmode, NULL_RTX);
1350 /* Store dhc into the first word of the newly allocated buffer. */
1352 dhc = get_dynamic_handler_chain ();
1353 dcc = gen_rtx_MEM (Pmode, plus_constant (XEXP (arg, 0),
1354 GET_MODE_SIZE (Pmode)));
1355 emit_move_insn (arg, dhc);
1357 /* Zero out the start of the cleanup chain. */
1358 emit_move_insn (dcc, const0_rtx);
1360 /* The jmpbuf starts two words into the area allocated. */
1361 buf = plus_constant (XEXP (arg, 0), GET_MODE_SIZE (Pmode)*2);
1363 #ifdef DONT_USE_BUILTIN_SETJMP
1364 x = emit_library_call_value (setjmp_libfunc, NULL_RTX, 1,
1365 TYPE_MODE (integer_type_node), 1,
1367 /* If we come back here for a catch, transfer control to the handler. */
1368 jumpif_rtx (x, ehstack.top->entry->exception_handler_label);
1371 /* A label to continue execution for the no exception case. */
1372 rtx noex = gen_label_rtx();
1373 x = expand_builtin_setjmp (buf, NULL_RTX, noex,
1374 ehstack.top->entry->exception_handler_label);
1379 /* We are committed to this, so update the handler chain. */
1381 emit_move_insn (dhc, force_operand (XEXP (arg, 0), NULL_RTX));
1384 /* Start an exception handling region for the given cleanup action.
1385 All instructions emitted after this point are considered to be part
1386 of the region until expand_eh_region_end is invoked. CLEANUP is
1387 the cleanup action to perform. The return value is true if the
1388 exception region was optimized away. If that case,
1389 expand_eh_region_end does not need to be called for this cleanup,
1392 This routine notices one particular common case in C++ code
1393 generation, and optimizes it so as to not need the exception
1394 region. It works by creating a dynamic cleanup action, instead of
1395 a using an exception region. */
1398 expand_eh_region_start_tree (decl, cleanup)
1402 /* This is the old code. */
1406 /* The optimization only applies to actions protected with
1407 terminate, and only applies if we are using the setjmp/longjmp
1409 if (exceptions_via_longjmp
1410 && protect_cleanup_actions_with_terminate)
1415 /* Ignore any UNSAVE_EXPR. */
1416 if (TREE_CODE (cleanup) == UNSAVE_EXPR)
1417 cleanup = TREE_OPERAND (cleanup, 0);
1419 /* Further, it only applies if the action is a call, if there
1420 are 2 arguments, and if the second argument is 2. */
1422 if (TREE_CODE (cleanup) == CALL_EXPR
1423 && (args = TREE_OPERAND (cleanup, 1))
1424 && (func = TREE_OPERAND (cleanup, 0))
1425 && (arg = TREE_VALUE (args))
1426 && (args = TREE_CHAIN (args))
1428 /* is the second argument 2? */
1429 && TREE_CODE (TREE_VALUE (args)) == INTEGER_CST
1430 && compare_tree_int (TREE_VALUE (args), 2) == 0
1432 /* Make sure there are no other arguments. */
1433 && TREE_CHAIN (args) == NULL_TREE)
1435 /* Arrange for returns and gotos to pop the entry we make on the
1436 dynamic cleanup stack. */
1437 expand_dcc_cleanup (decl);
1438 start_dynamic_cleanup (func, arg);
1443 expand_eh_region_start_for_decl (decl);
1444 ehstack.top->entry->finalization = cleanup;
1449 /* Just like expand_eh_region_start, except if a cleanup action is
1450 entered on the cleanup chain, the TREE_PURPOSE of the element put
1451 on the chain is DECL. DECL should be the associated VAR_DECL, if
1452 any, otherwise it should be NULL_TREE. */
1455 expand_eh_region_start_for_decl (decl)
1460 /* This is the old code. */
1464 /* We need a new block to record the start and end of the
1465 dynamic handler chain. We also want to prevent jumping into
1467 expand_start_bindings (2);
1469 /* But we don't need or want a new temporary level. */
1472 /* Mark this block as created by expand_eh_region_start. This
1473 is so that we can pop the block with expand_end_bindings
1475 mark_block_as_eh_region ();
1477 if (exceptions_via_longjmp)
1479 /* Arrange for returns and gotos to pop the entry we make on the
1480 dynamic handler stack. */
1481 expand_dhc_cleanup (decl);
1484 push_eh_entry (&ehstack);
1485 note = emit_note (NULL_PTR, NOTE_INSN_EH_REGION_BEG);
1486 NOTE_EH_HANDLER (note)
1487 = CODE_LABEL_NUMBER (ehstack.top->entry->exception_handler_label);
1488 if (exceptions_via_longjmp)
1489 start_dynamic_handler ();
1492 /* Start an exception handling region. All instructions emitted after
1493 this point are considered to be part of the region until
1494 expand_eh_region_end is invoked. */
1497 expand_eh_region_start ()
1499 expand_eh_region_start_for_decl (NULL_TREE);
1502 /* End an exception handling region. The information about the region
1503 is found on the top of ehstack.
1505 HANDLER is either the cleanup for the exception region, or if we're
1506 marking the end of a try block, HANDLER is integer_zero_node.
1508 HANDLER will be transformed to rtl when expand_leftover_cleanups
1512 expand_eh_region_end (handler)
1515 struct eh_entry *entry;
1516 struct eh_node *node;
1523 entry = pop_eh_entry (&ehstack);
1525 note = emit_note (NULL_PTR, NOTE_INSN_EH_REGION_END);
1526 ret = NOTE_EH_HANDLER (note)
1527 = CODE_LABEL_NUMBER (entry->exception_handler_label);
1528 if (exceptions_via_longjmp == 0 && ! flag_new_exceptions
1529 /* We share outer_context between regions; only emit it once. */
1530 && INSN_UID (entry->outer_context) == 0)
1534 label = gen_label_rtx ();
1537 /* Emit a label marking the end of this exception region that
1538 is used for rethrowing into the outer context. */
1539 emit_label (entry->outer_context);
1540 expand_internal_throw ();
1545 entry->finalization = handler;
1547 /* create region entry in final exception table */
1548 r = new_eh_region_entry (NOTE_EH_HANDLER (note), entry->rethrow_label);
1550 enqueue_eh_entry (ehqueue, entry);
1552 /* If we have already started ending the bindings, don't recurse. */
1553 if (is_eh_region ())
1555 /* Because we don't need or want a new temporary level and
1556 because we didn't create one in expand_eh_region_start,
1557 create a fake one now to avoid removing one in
1558 expand_end_bindings. */
1561 mark_block_as_not_eh_region ();
1563 expand_end_bindings (NULL_TREE, 0, 0);
1566 /* Go through the goto handlers in the queue, emitting their
1567 handlers if we now have enough information to do so. */
1568 for (node = ehqueue->head; node; node = node->chain)
1569 if (node->entry->goto_entry_p
1570 && node->entry->outer_context == entry->rethrow_label)
1571 emit_cleanup_handler (node->entry);
1573 /* We can't emit handlers for goto entries until their scopes are
1574 complete because we don't know where they need to rethrow to,
1576 if (entry->finalization != integer_zero_node
1577 && (!entry->goto_entry_p
1578 || find_func_region_from_symbol (entry->outer_context) != -1))
1579 emit_cleanup_handler (entry);
1582 /* End the EH region for a goto fixup. We only need them in the region-based
1586 expand_fixup_region_start ()
1588 if (! doing_eh (0) || exceptions_via_longjmp)
1591 expand_eh_region_start ();
1592 /* Mark this entry as the entry for a goto. */
1593 ehstack.top->entry->goto_entry_p = 1;
1596 /* End the EH region for a goto fixup. CLEANUP is the cleanup we just
1597 expanded; to avoid running it twice if it throws, we look through the
1598 ehqueue for a matching region and rethrow from its outer_context. */
1601 expand_fixup_region_end (cleanup)
1604 struct eh_node *node;
1607 if (! doing_eh (0) || exceptions_via_longjmp)
1610 for (node = ehstack.top; node && node->entry->finalization != cleanup; )
1613 for (node = ehqueue->head; node && node->entry->finalization != cleanup; )
1618 /* If the outer context label has not been issued yet, we don't want
1619 to issue it as a part of this region, unless this is the
1620 correct region for the outer context. If we did, then the label for
1621 the outer context will be WITHIN the begin/end labels,
1622 and we could get an infinte loop when it tried to rethrow, or just
1623 generally incorrect execution following a throw. */
1625 if (flag_new_exceptions)
1628 dont_issue = ((INSN_UID (node->entry->outer_context) == 0)
1629 && (ehstack.top->entry != node->entry));
1631 ehstack.top->entry->outer_context = node->entry->outer_context;
1633 /* Since we are rethrowing to the OUTER region, we know we don't need
1634 a jump around sequence for this region, so we'll pretend the outer
1635 context label has been issued by setting INSN_UID to 1, then clearing
1636 it again afterwards. */
1639 INSN_UID (node->entry->outer_context) = 1;
1641 /* Just rethrow. size_zero_node is just a NOP. */
1642 expand_eh_region_end (size_zero_node);
1645 INSN_UID (node->entry->outer_context) = 0;
1648 /* If we are using the setjmp/longjmp EH codegen method, we emit a
1649 call to __sjthrow. Otherwise, we emit a call to __throw. */
1654 if (exceptions_via_longjmp)
1656 emit_library_call (sjthrow_libfunc, 0, VOIDmode, 0);
1660 #ifdef JUMP_TO_THROW
1661 emit_indirect_jump (throw_libfunc);
1663 emit_library_call (throw_libfunc, 0, VOIDmode, 0);
1669 /* Throw the current exception. If appropriate, this is done by jumping
1670 to the next handler. */
1673 expand_internal_throw ()
1678 /* Called from expand_exception_blocks and expand_end_catch_block to
1679 emit any pending handlers/cleanups queued from expand_eh_region_end. */
1682 expand_leftover_cleanups ()
1684 struct eh_entry *entry;
1686 for (entry = dequeue_eh_entry (ehqueue);
1688 entry = dequeue_eh_entry (ehqueue))
1690 /* A leftover try block. Shouldn't be one here. */
1691 if (entry->finalization == integer_zero_node)
1698 /* Called at the start of a block of try statements. */
1700 expand_start_try_stmts ()
1705 expand_eh_region_start ();
1708 /* Called to begin a catch clause. The parameter is the object which
1709 will be passed to the runtime type check routine. */
1711 start_catch_handler (rtime)
1715 int insn_region_num;
1716 int eh_region_entry;
1721 handler_label = catchstack.top->entry->exception_handler_label;
1722 insn_region_num = CODE_LABEL_NUMBER (handler_label);
1723 eh_region_entry = find_func_region (insn_region_num);
1725 /* If we've already issued this label, pick a new one */
1726 if (catchstack.top->entry->label_used)
1727 handler_label = gen_exception_label ();
1729 catchstack.top->entry->label_used = 1;
1731 receive_exception_label (handler_label);
1733 add_new_handler (eh_region_entry, get_new_handler (handler_label, rtime));
1735 if (flag_new_exceptions && ! exceptions_via_longjmp)
1738 /* Under the old mechanism, as well as setjmp/longjmp, we need to
1739 issue code to compare 'rtime' to the value in eh_info, via the
1740 matching function in eh_info. If its is false, we branch around
1741 the handler we are about to issue. */
1743 if (rtime != NULL_TREE && rtime != CATCH_ALL_TYPE)
1745 rtx call_rtx, rtime_address;
1747 if (catchstack.top->entry->false_label != NULL_RTX)
1749 error ("Never issued previous false_label");
1752 catchstack.top->entry->false_label = gen_exception_label ();
1754 rtime_address = expand_expr (rtime, NULL_RTX, Pmode, EXPAND_INITIALIZER);
1755 #ifdef POINTERS_EXTEND_UNSIGNED
1756 rtime_address = convert_memory_address (Pmode, rtime_address);
1758 rtime_address = force_reg (Pmode, rtime_address);
1760 /* Now issue the call, and branch around handler if needed */
1761 call_rtx = emit_library_call_value (eh_rtime_match_libfunc, NULL_RTX,
1762 0, TYPE_MODE (integer_type_node),
1763 1, rtime_address, Pmode);
1765 /* Did the function return true? */
1766 emit_cmp_and_jump_insns (call_rtx, const0_rtx, EQ, NULL_RTX,
1767 GET_MODE (call_rtx), 0, 0,
1768 catchstack.top->entry->false_label);
1772 /* Called to end a catch clause. If we aren't using the new exception
1773 model tabel mechanism, we need to issue the branch-around label
1774 for the end of the catch block. */
1777 end_catch_handler ()
1782 if (flag_new_exceptions && ! exceptions_via_longjmp)
1788 /* A NULL label implies the catch clause was a catch all or cleanup */
1789 if (catchstack.top->entry->false_label == NULL_RTX)
1792 emit_label (catchstack.top->entry->false_label);
1793 catchstack.top->entry->false_label = NULL_RTX;
1796 /* Save away the current ehqueue. */
1802 q = (struct eh_queue *) xcalloc (1, sizeof (struct eh_queue));
1807 /* Restore a previously pushed ehqueue. */
1813 expand_leftover_cleanups ();
1819 /* Emit the handler specified by ENTRY. */
1822 emit_cleanup_handler (entry)
1823 struct eh_entry *entry;
1828 /* Since the cleanup could itself contain try-catch blocks, we
1829 squirrel away the current queue and replace it when we are done
1830 with this function. */
1833 /* Put these handler instructions in a sequence. */
1834 do_pending_stack_adjust ();
1837 /* Emit the label for the cleanup handler for this region, and
1838 expand the code for the handler.
1840 Note that a catch region is handled as a side-effect here; for a
1841 try block, entry->finalization will contain integer_zero_node, so
1842 no code will be generated in the expand_expr call below. But, the
1843 label for the handler will still be emitted, so any code emitted
1844 after this point will end up being the handler. */
1846 receive_exception_label (entry->exception_handler_label);
1848 /* register a handler for this cleanup region */
1849 add_new_handler (find_func_region (CODE_LABEL_NUMBER (entry->exception_handler_label)),
1850 get_new_handler (entry->exception_handler_label, NULL));
1852 /* And now generate the insns for the cleanup handler. */
1853 expand_expr (entry->finalization, const0_rtx, VOIDmode, 0);
1855 prev = get_last_insn ();
1856 if (prev == NULL || GET_CODE (prev) != BARRIER)
1857 /* Code to throw out to outer context when we fall off end of the
1858 handler. We can't do this here for catch blocks, so it's done
1859 in expand_end_all_catch instead. */
1860 expand_rethrow (entry->outer_context);
1862 /* Finish this sequence. */
1863 do_pending_stack_adjust ();
1864 handler_insns = get_insns ();
1867 /* And add it to the CATCH_CLAUSES. */
1868 push_to_sequence (catch_clauses);
1869 emit_insns (handler_insns);
1870 catch_clauses = get_insns ();
1873 /* Now we've left the handler. */
1877 /* Generate RTL for the start of a group of catch clauses.
1879 It is responsible for starting a new instruction sequence for the
1880 instructions in the catch block, and expanding the handlers for the
1881 internally-generated exception regions nested within the try block
1882 corresponding to this catch block. */
1885 expand_start_all_catch ()
1887 struct eh_entry *entry;
1894 outer_context = ehstack.top->entry->outer_context;
1896 /* End the try block. */
1897 expand_eh_region_end (integer_zero_node);
1899 emit_line_note (input_filename, lineno);
1900 label = build_decl (LABEL_DECL, NULL_TREE, NULL_TREE);
1902 /* The label for the exception handling block that we will save.
1903 This is Lresume in the documentation. */
1904 expand_label (label);
1906 /* Push the label that points to where normal flow is resumed onto
1907 the top of the label stack. */
1908 push_label_entry (&caught_return_label_stack, NULL_RTX, label);
1910 /* Start a new sequence for all the catch blocks. We will add this
1911 to the global sequence catch_clauses when we have completed all
1912 the handlers in this handler-seq. */
1915 /* Throw away entries in the queue that we won't need anymore. We
1916 need entries for regions that have ended but to which there might
1917 still be gotos pending. */
1918 for (entry = dequeue_eh_entry (ehqueue);
1919 entry->finalization != integer_zero_node;
1920 entry = dequeue_eh_entry (ehqueue))
1923 /* At this point, all the cleanups are done, and the ehqueue now has
1924 the current exception region at its head. We dequeue it, and put it
1925 on the catch stack. */
1926 push_entry (&catchstack, entry);
1928 /* If we are not doing setjmp/longjmp EH, because we are reordered
1929 out of line, we arrange to rethrow in the outer context. We need to
1930 do this because we are not physically within the region, if any, that
1931 logically contains this catch block. */
1932 if (! exceptions_via_longjmp)
1934 expand_eh_region_start ();
1935 ehstack.top->entry->outer_context = outer_context;
1940 /* Finish up the catch block. At this point all the insns for the
1941 catch clauses have already been generated, so we only have to add
1942 them to the catch_clauses list. We also want to make sure that if
1943 we fall off the end of the catch clauses that we rethrow to the
1947 expand_end_all_catch ()
1949 rtx new_catch_clause;
1950 struct eh_entry *entry;
1955 /* Dequeue the current catch clause region. */
1956 entry = pop_eh_entry (&catchstack);
1959 if (! exceptions_via_longjmp)
1961 rtx outer_context = ehstack.top->entry->outer_context;
1963 /* Finish the rethrow region. size_zero_node is just a NOP. */
1964 expand_eh_region_end (size_zero_node);
1965 /* New exceptions handling models will never have a fall through
1966 of a catch clause */
1967 if (!flag_new_exceptions)
1968 expand_rethrow (outer_context);
1971 expand_rethrow (NULL_RTX);
1973 /* Code to throw out to outer context, if we fall off end of catch
1974 handlers. This is rethrow (Lresume, same id, same obj) in the
1975 documentation. We use Lresume because we know that it will throw
1976 to the correct context.
1978 In other words, if the catch handler doesn't exit or return, we
1979 do a "throw" (using the address of Lresume as the point being
1980 thrown from) so that the outer EH region can then try to process
1983 /* Now we have the complete catch sequence. */
1984 new_catch_clause = get_insns ();
1987 /* This level of catch blocks is done, so set up the successful
1988 catch jump label for the next layer of catch blocks. */
1989 pop_label_entry (&caught_return_label_stack);
1990 pop_label_entry (&outer_context_label_stack);
1992 /* Add the new sequence of catches to the main one for this function. */
1993 push_to_sequence (catch_clauses);
1994 emit_insns (new_catch_clause);
1995 catch_clauses = get_insns ();
1998 /* Here we fall through into the continuation code. */
2001 /* Rethrow from the outer context LABEL. */
2004 expand_rethrow (label)
2007 if (exceptions_via_longjmp)
2010 if (flag_new_exceptions)
2014 if (label == NULL_RTX)
2015 label = last_rethrow_symbol;
2016 emit_library_call (rethrow_libfunc, 0, VOIDmode, 1, label, Pmode);
2017 region = find_func_region (eh_region_from_symbol (label));
2018 /* If the region is -1, it doesn't exist yet. We shouldn't be
2019 trying to rethrow there yet. */
2022 function_eh_regions[region].rethrow_ref = 1;
2024 /* Search backwards for the actual call insn. */
2025 insn = get_last_insn ();
2026 while (GET_CODE (insn) != CALL_INSN)
2027 insn = PREV_INSN (insn);
2028 delete_insns_since (insn);
2030 /* Mark the label/symbol on the call. */
2031 REG_NOTES (insn) = gen_rtx_EXPR_LIST (REG_EH_RETHROW, label,
2039 /* Begin a region that will contain entries created with
2040 add_partial_entry. */
2043 begin_protect_partials ()
2045 /* Put the entry on the function obstack. */
2046 push_obstacks_nochange ();
2047 resume_temporary_allocation ();
2049 /* Push room for a new list. */
2050 protect_list = tree_cons (NULL_TREE, NULL_TREE, protect_list);
2052 /* We're done with the function obstack now. */
2056 /* End all the pending exception regions on protect_list. The handlers
2057 will be emitted when expand_leftover_cleanups is invoked. */
2060 end_protect_partials ()
2064 /* For backwards compatibility, we allow callers to omit the call to
2065 begin_protect_partials for the outermost region. So,
2066 PROTECT_LIST may be NULL. */
2070 /* End all the exception regions. */
2071 for (t = TREE_VALUE (protect_list); t; t = TREE_CHAIN (t))
2072 expand_eh_region_end (TREE_VALUE (t));
2074 /* Pop the topmost entry. */
2075 protect_list = TREE_CHAIN (protect_list);
2079 /* Arrange for __terminate to be called if there is an unhandled throw
2083 protect_with_terminate (e)
2086 /* We only need to do this when using setjmp/longjmp EH and the
2087 language requires it, as otherwise we protect all of the handlers
2088 at once, if we need to. */
2089 if (exceptions_via_longjmp && protect_cleanup_actions_with_terminate)
2091 tree handler, result;
2093 /* All cleanups must be on the function_obstack. */
2094 push_obstacks_nochange ();
2095 resume_temporary_allocation ();
2097 handler = make_node (RTL_EXPR);
2098 TREE_TYPE (handler) = void_type_node;
2099 RTL_EXPR_RTL (handler) = const0_rtx;
2100 TREE_SIDE_EFFECTS (handler) = 1;
2101 start_sequence_for_rtl_expr (handler);
2103 emit_library_call (terminate_libfunc, 0, VOIDmode, 0);
2106 RTL_EXPR_SEQUENCE (handler) = get_insns ();
2109 result = build (TRY_CATCH_EXPR, TREE_TYPE (e), e, handler);
2110 TREE_SIDE_EFFECTS (result) = TREE_SIDE_EFFECTS (e);
2111 TREE_THIS_VOLATILE (result) = TREE_THIS_VOLATILE (e);
2112 TREE_READONLY (result) = TREE_READONLY (e);
2122 /* The exception table that we build that is used for looking up and
2123 dispatching exceptions, the current number of entries, and its
2124 maximum size before we have to extend it.
2126 The number in eh_table is the code label number of the exception
2127 handler for the region. This is added by add_eh_table_entry and
2128 used by output_exception_table_entry. */
2130 static int *eh_table = NULL;
2131 static int eh_table_size = 0;
2132 static int eh_table_max_size = 0;
2134 /* Note the need for an exception table entry for region N. If we
2135 don't need to output an explicit exception table, avoid all of the
2138 Called from final_scan_insn when a NOTE_INSN_EH_REGION_BEG is seen.
2139 (Or NOTE_INSN_EH_REGION_END sometimes)
2140 N is the NOTE_EH_HANDLER of the note, which comes from the code
2141 label number of the exception handler for the region. */
2144 add_eh_table_entry (n)
2147 #ifndef OMIT_EH_TABLE
2148 if (eh_table_size >= eh_table_max_size)
2152 eh_table_max_size += eh_table_max_size>>1;
2154 if (eh_table_max_size < 0)
2157 eh_table = (int *) xrealloc (eh_table,
2158 eh_table_max_size * sizeof (int));
2162 eh_table_max_size = 252;
2163 eh_table = (int *) xmalloc (eh_table_max_size * sizeof (int));
2166 eh_table[eh_table_size++] = n;
2170 /* Return a non-zero value if we need to output an exception table.
2172 On some platforms, we don't have to output a table explicitly.
2173 This routine doesn't mean we don't have one. */
2176 exception_table_p ()
2184 /* Output the entry of the exception table corresponding to the
2185 exception region numbered N to file FILE.
2187 N is the code label number corresponding to the handler of the
2191 output_exception_table_entry (file, n)
2197 struct handler_info *handler = get_first_handler (n);
2198 int index = find_func_region (n);
2201 /* Form and emit the rethrow label, if needed */
2202 if (flag_new_exceptions
2203 && (handler || function_eh_regions[index].rethrow_ref))
2204 rethrow = function_eh_regions[index].rethrow_label;
2208 for ( ; handler != NULL || rethrow != NULL_RTX; handler = handler->next)
2210 /* rethrow label should indicate the LAST entry for a region */
2211 if (rethrow != NULL_RTX && (handler == NULL || handler->next == NULL))
2213 ASM_GENERATE_INTERNAL_LABEL (buf, "LRTH", n);
2214 assemble_label(buf);
2218 ASM_GENERATE_INTERNAL_LABEL (buf, "LEHB", n);
2219 sym = gen_rtx_SYMBOL_REF (Pmode, buf);
2220 assemble_integer (sym, POINTER_SIZE / BITS_PER_UNIT, 1);
2222 ASM_GENERATE_INTERNAL_LABEL (buf, "LEHE", n);
2223 sym = gen_rtx_SYMBOL_REF (Pmode, buf);
2224 assemble_integer (sym, POINTER_SIZE / BITS_PER_UNIT, 1);
2226 if (handler == NULL)
2227 assemble_integer (GEN_INT (0), POINTER_SIZE / BITS_PER_UNIT, 1);
2230 ASM_GENERATE_INTERNAL_LABEL (buf, "L", handler->handler_number);
2231 sym = gen_rtx_SYMBOL_REF (Pmode, buf);
2232 assemble_integer (sym, POINTER_SIZE / BITS_PER_UNIT, 1);
2235 if (flag_new_exceptions)
2237 if (handler == NULL || handler->type_info == NULL)
2238 assemble_integer (const0_rtx, POINTER_SIZE / BITS_PER_UNIT, 1);
2240 if (handler->type_info == CATCH_ALL_TYPE)
2241 assemble_integer (GEN_INT (CATCH_ALL_TYPE),
2242 POINTER_SIZE / BITS_PER_UNIT, 1);
2244 output_constant ((tree)(handler->type_info),
2245 POINTER_SIZE / BITS_PER_UNIT);
2247 putc ('\n', file); /* blank line */
2248 /* We only output the first label under the old scheme */
2249 if (! flag_new_exceptions || handler == NULL)
2254 /* Output the exception table if we have and need one. */
2256 static short language_code = 0;
2257 static short version_code = 0;
2259 /* This routine will set the language code for exceptions. */
2261 set_exception_lang_code (code)
2264 language_code = code;
2267 /* This routine will set the language version code for exceptions. */
2269 set_exception_version_code (code)
2272 version_code = code;
2277 output_exception_table ()
2281 extern FILE *asm_out_file;
2283 if (! doing_eh (0) || ! eh_table)
2286 exception_section ();
2288 /* Beginning marker for table. */
2289 assemble_align (GET_MODE_ALIGNMENT (ptr_mode));
2290 assemble_label ("__EXCEPTION_TABLE__");
2292 if (flag_new_exceptions)
2294 assemble_integer (GEN_INT (NEW_EH_RUNTIME),
2295 POINTER_SIZE / BITS_PER_UNIT, 1);
2296 assemble_integer (GEN_INT (language_code), 2 , 1);
2297 assemble_integer (GEN_INT (version_code), 2 , 1);
2299 /* Add enough padding to make sure table aligns on a pointer boundry. */
2300 i = GET_MODE_ALIGNMENT (ptr_mode) / BITS_PER_UNIT - 4;
2301 for ( ; i < 0; i = i + GET_MODE_ALIGNMENT (ptr_mode) / BITS_PER_UNIT)
2304 assemble_integer (const0_rtx, i , 1);
2306 /* Generate the label for offset calculations on rethrows. */
2307 ASM_GENERATE_INTERNAL_LABEL (buf, "LRTH", 0);
2308 assemble_label(buf);
2311 for (i = 0; i < eh_table_size; ++i)
2312 output_exception_table_entry (asm_out_file, eh_table[i]);
2315 clear_function_eh_region ();
2317 /* Ending marker for table. */
2318 /* Generate the label for end of table. */
2319 ASM_GENERATE_INTERNAL_LABEL (buf, "LRTH", CODE_LABEL_NUMBER (final_rethrow));
2320 assemble_label(buf);
2321 assemble_integer (constm1_rtx, POINTER_SIZE / BITS_PER_UNIT, 1);
2323 /* For binary compatibility, the old __throw checked the second
2324 position for a -1, so we should output at least 2 -1's */
2325 if (! flag_new_exceptions)
2326 assemble_integer (constm1_rtx, POINTER_SIZE / BITS_PER_UNIT, 1);
2328 putc ('\n', asm_out_file); /* blank line */
2331 /* Emit code to get EH context.
2333 We have to scan thru the code to find possible EH context registers.
2334 Inlined functions may use it too, and thus we'll have to be able
2337 This is done only if using exceptions_via_longjmp. */
2348 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
2349 if (GET_CODE (insn) == INSN
2350 && GET_CODE (PATTERN (insn)) == USE)
2352 rtx reg = find_reg_note (insn, REG_EH_CONTEXT, 0);
2359 /* If this is the first use insn, emit the call here. This
2360 will always be at the top of our function, because if
2361 expand_inline_function notices a REG_EH_CONTEXT note, it
2362 adds a use insn to this function as well. */
2364 ehc = call_get_eh_context ();
2366 emit_move_insn (XEXP (reg, 0), ehc);
2367 insns = get_insns ();
2370 emit_insns_before (insns, insn);
2375 /* Scan the current insns and build a list of handler labels. The
2376 resulting list is placed in the global variable exception_handler_labels.
2378 It is called after the last exception handling region is added to
2379 the current function (when the rtl is almost all built for the
2380 current function) and before the jump optimization pass. */
2383 find_exception_handler_labels ()
2387 exception_handler_labels = NULL_RTX;
2389 /* If we aren't doing exception handling, there isn't much to check. */
2393 /* For each start of a region, add its label to the list. */
2395 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
2397 struct handler_info* ptr;
2398 if (GET_CODE (insn) == NOTE
2399 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG)
2401 ptr = get_first_handler (NOTE_EH_HANDLER (insn));
2402 for ( ; ptr; ptr = ptr->next)
2404 /* make sure label isn't in the list already */
2406 for (x = exception_handler_labels; x; x = XEXP (x, 1))
2407 if (XEXP (x, 0) == ptr->handler_label)
2410 exception_handler_labels = gen_rtx_EXPR_LIST (VOIDmode,
2411 ptr->handler_label, exception_handler_labels);
2417 /* Return a value of 1 if the parameter label number is an exception handler
2418 label. Return 0 otherwise. */
2421 is_exception_handler_label (lab)
2425 for (x = exception_handler_labels ; x ; x = XEXP (x, 1))
2426 if (lab == CODE_LABEL_NUMBER (XEXP (x, 0)))
2431 /* Perform sanity checking on the exception_handler_labels list.
2433 Can be called after find_exception_handler_labels is called to
2434 build the list of exception handlers for the current function and
2435 before we finish processing the current function. */
2438 check_exception_handler_labels ()
2442 /* If we aren't doing exception handling, there isn't much to check. */
2446 /* Make sure there is no more than 1 copy of a label */
2447 for (insn = exception_handler_labels; insn; insn = XEXP (insn, 1))
2450 for (insn2 = exception_handler_labels; insn2; insn2 = XEXP (insn2, 1))
2451 if (XEXP (insn, 0) == XEXP (insn2, 0))
2454 warning ("Counted %d copies of EH region %d in list.\n", count,
2455 CODE_LABEL_NUMBER (insn));
2460 /* Mark the children of NODE for GC. */
2464 struct eh_node *node;
2470 ggc_mark_rtx (node->entry->outer_context);
2471 ggc_mark_rtx (node->entry->exception_handler_label);
2472 ggc_mark_tree (node->entry->finalization);
2473 ggc_mark_rtx (node->entry->false_label);
2474 ggc_mark_rtx (node->entry->rethrow_label);
2476 node = node ->chain;
2480 /* Mark S for GC. */
2487 mark_eh_node (s->top);
2490 /* Mark Q for GC. */
2498 mark_eh_node (q->head);
2503 /* Mark NODE for GC. A label_node contains a union containing either
2504 a tree or an rtx. This label_node will contain a tree. */
2507 mark_tree_label_node (node)
2508 struct label_node *node;
2512 ggc_mark_tree (node->u.tlabel);
2517 /* Mark EH for GC. */
2521 struct eh_status *eh;
2526 mark_eh_stack (&eh->x_ehstack);
2527 mark_eh_stack (&eh->x_catchstack);
2528 mark_eh_queue (eh->x_ehqueue);
2529 ggc_mark_rtx (eh->x_catch_clauses);
2531 lang_mark_false_label_stack (eh->x_false_label_stack);
2532 mark_tree_label_node (eh->x_caught_return_label_stack);
2534 ggc_mark_tree (eh->x_protect_list);
2535 ggc_mark_rtx (eh->ehc);
2536 ggc_mark_rtx (eh->x_eh_return_stub_label);
2539 /* Mark ARG (which is really a struct func_eh_entry**) for GC. */
2542 mark_func_eh_entry (arg)
2545 struct func_eh_entry *fee;
2546 struct handler_info *h;
2549 fee = *((struct func_eh_entry **) arg);
2551 for (i = 0; i < current_func_eh_entry; ++i)
2553 ggc_mark_rtx (fee->rethrow_label);
2554 for (h = fee->handlers; h; h = h->next)
2556 ggc_mark_rtx (h->handler_label);
2557 if (h->type_info != CATCH_ALL_TYPE)
2558 ggc_mark_tree ((tree) h->type_info);
2561 /* Skip to the next entry in the array. */
2566 /* This group of functions initializes the exception handling data
2567 structures at the start of the compilation, initializes the data
2568 structures at the start of a function, and saves and restores the
2569 exception handling data structures for the start/end of a nested
2572 /* Toplevel initialization for EH things. */
2577 first_rethrow_symbol = create_rethrow_ref (0);
2578 final_rethrow = gen_exception_label ();
2579 last_rethrow_symbol = create_rethrow_ref (CODE_LABEL_NUMBER (final_rethrow));
2581 ggc_add_rtx_root (&exception_handler_labels, 1);
2582 ggc_add_rtx_root (&eh_return_context, 1);
2583 ggc_add_rtx_root (&eh_return_stack_adjust, 1);
2584 ggc_add_rtx_root (&eh_return_handler, 1);
2585 ggc_add_rtx_root (&first_rethrow_symbol, 1);
2586 ggc_add_rtx_root (&final_rethrow, 1);
2587 ggc_add_rtx_root (&last_rethrow_symbol, 1);
2588 ggc_add_root (&function_eh_regions, 1, sizeof (function_eh_regions),
2589 mark_func_eh_entry);
2592 /* Initialize the per-function EH information. */
2595 init_eh_for_function ()
2597 cfun->eh = (struct eh_status *) xcalloc (1, sizeof (struct eh_status));
2598 ehqueue = (struct eh_queue *) xcalloc (1, sizeof (struct eh_queue));
2599 eh_return_context = NULL_RTX;
2600 eh_return_stack_adjust = NULL_RTX;
2601 eh_return_handler = NULL_RTX;
2608 free (f->eh->x_ehqueue);
2613 /* This section is for the exception handling specific optimization
2614 pass. First are the internal routines, and then the main
2615 optimization pass. */
2617 /* Determine if the given INSN can throw an exception. */
2623 if (GET_CODE (insn) == INSN
2624 && GET_CODE (PATTERN (insn)) == SEQUENCE)
2625 insn = XVECEXP (PATTERN (insn), 0, 0);
2627 /* Calls can always potentially throw exceptions, unless they have
2628 a REG_EH_REGION note with a value of 0 or less. */
2629 if (GET_CODE (insn) == CALL_INSN)
2631 rtx note = find_reg_note (insn, REG_EH_REGION, NULL_RTX);
2632 if (!note || XINT (XEXP (note, 0), 0) > 0)
2636 if (asynchronous_exceptions)
2638 /* If we wanted asynchronous exceptions, then everything but NOTEs
2639 and CODE_LABELs could throw. */
2640 if (GET_CODE (insn) != NOTE && GET_CODE (insn) != CODE_LABEL)
2647 /* Return nonzero if nothing in this function can throw. */
2650 nothrow_function_p ()
2654 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
2655 if (can_throw (insn))
2657 for (insn = current_function_epilogue_delay_list; insn;
2658 insn = XEXP (insn, 1))
2659 if (can_throw (insn))
2665 /* Scan a exception region looking for the matching end and then
2666 remove it if possible. INSN is the start of the region, N is the
2667 region number, and DELETE_OUTER is to note if anything in this
2670 Regions are removed if they cannot possibly catch an exception.
2671 This is determined by invoking can_throw on each insn within the
2672 region; if can_throw returns true for any of the instructions, the
2673 region can catch an exception, since there is an insn within the
2674 region that is capable of throwing an exception.
2676 Returns the NOTE_INSN_EH_REGION_END corresponding to this region, or
2677 calls abort if it can't find one.
2679 Can abort if INSN is not a NOTE_INSN_EH_REGION_BEGIN, or if N doesn't
2680 correspond to the region number, or if DELETE_OUTER is NULL. */
2683 scan_region (insn, n, delete_outer)
2690 /* Assume we can delete the region. */
2693 /* Can't delete something which is rethrown from. */
2694 if (rethrow_used (n))
2697 if (insn == NULL_RTX
2698 || GET_CODE (insn) != NOTE
2699 || NOTE_LINE_NUMBER (insn) != NOTE_INSN_EH_REGION_BEG
2700 || NOTE_EH_HANDLER (insn) != n
2701 || delete_outer == NULL)
2704 insn = NEXT_INSN (insn);
2706 /* Look for the matching end. */
2707 while (! (GET_CODE (insn) == NOTE
2708 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_END))
2710 /* If anything can throw, we can't remove the region. */
2711 if (delete && can_throw (insn))
2716 /* Watch out for and handle nested regions. */
2717 if (GET_CODE (insn) == NOTE
2718 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG)
2720 insn = scan_region (insn, NOTE_EH_HANDLER (insn), &delete);
2723 insn = NEXT_INSN (insn);
2726 /* The _BEG/_END NOTEs must match and nest. */
2727 if (NOTE_EH_HANDLER (insn) != n)
2730 /* If anything in this exception region can throw, we can throw. */
2735 /* Delete the start and end of the region. */
2736 delete_insn (start);
2739 /* We no longer removed labels here, since flow will now remove any
2740 handler which cannot be called any more. */
2743 /* Only do this part if we have built the exception handler
2745 if (exception_handler_labels)
2747 rtx x, *prev = &exception_handler_labels;
2749 /* Find it in the list of handlers. */
2750 for (x = exception_handler_labels; x; x = XEXP (x, 1))
2752 rtx label = XEXP (x, 0);
2753 if (CODE_LABEL_NUMBER (label) == n)
2755 /* If we are the last reference to the handler,
2757 if (--LABEL_NUSES (label) == 0)
2758 delete_insn (label);
2762 /* Remove it from the list of exception handler
2763 labels, if we are optimizing. If we are not, then
2764 leave it in the list, as we are not really going to
2765 remove the region. */
2766 *prev = XEXP (x, 1);
2773 prev = &XEXP (x, 1);
2781 /* Perform various interesting optimizations for exception handling
2784 We look for empty exception regions and make them go (away). The
2785 jump optimization code will remove the handler if nothing else uses
2789 exception_optimize ()
2794 /* Remove empty regions. */
2795 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
2797 if (GET_CODE (insn) == NOTE
2798 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG)
2800 /* Since scan_region will return the NOTE_INSN_EH_REGION_END
2801 insn, we will indirectly skip through all the insns
2802 inbetween. We are also guaranteed that the value of insn
2803 returned will be valid, as otherwise scan_region won't
2805 insn = scan_region (insn, NOTE_EH_HANDLER (insn), &n);
2810 /* This function determines whether the rethrow labels for any of the
2811 exception regions in the current function are used or not, and set
2812 the reference flag according. */
2815 update_rethrow_references ()
2819 int *saw_region, *saw_rethrow;
2821 if (!flag_new_exceptions)
2824 saw_region = (int *) xcalloc (current_func_eh_entry, sizeof (int));
2825 saw_rethrow = (int *) xcalloc (current_func_eh_entry, sizeof (int));
2827 /* Determine what regions exist, and whether there are any rethrows
2828 from those regions or not. */
2829 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
2830 if (GET_CODE (insn) == CALL_INSN)
2832 rtx note = find_reg_note (insn, REG_EH_RETHROW, NULL_RTX);
2835 region = eh_region_from_symbol (XEXP (note, 0));
2836 region = find_func_region (region);
2837 saw_rethrow[region] = 1;
2841 if (GET_CODE (insn) == NOTE)
2843 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG)
2845 region = find_func_region (NOTE_EH_HANDLER (insn));
2846 saw_region[region] = 1;
2850 /* For any regions we did see, set the referenced flag. */
2851 for (x = 0; x < current_func_eh_entry; x++)
2853 function_eh_regions[x].rethrow_ref = saw_rethrow[x];
2860 /* Various hooks for the DWARF 2 __throw routine. */
2862 /* Do any necessary initialization to access arbitrary stack frames.
2863 On the SPARC, this means flushing the register windows. */
2866 expand_builtin_unwind_init ()
2868 /* Set this so all the registers get saved in our frame; we need to be
2869 able to copy the saved values for any registers from frames we unwind. */
2870 current_function_has_nonlocal_label = 1;
2872 #ifdef SETUP_FRAME_ADDRESSES
2873 SETUP_FRAME_ADDRESSES ();
2877 /* Given a value extracted from the return address register or stack slot,
2878 return the actual address encoded in that value. */
2881 expand_builtin_extract_return_addr (addr_tree)
2884 rtx addr = expand_expr (addr_tree, NULL_RTX, Pmode, 0);
2885 return eh_outer_context (addr);
2888 /* Given an actual address in addr_tree, do any necessary encoding
2889 and return the value to be stored in the return address register or
2890 stack slot so the epilogue will return to that address. */
2893 expand_builtin_frob_return_addr (addr_tree)
2896 rtx addr = expand_expr (addr_tree, NULL_RTX, Pmode, 0);
2897 #ifdef RETURN_ADDR_OFFSET
2898 addr = plus_constant (addr, -RETURN_ADDR_OFFSET);
2903 /* Choose three registers for communication between the main body of
2904 __throw and the epilogue (or eh stub) and the exception handler.
2905 We must do this with hard registers because the epilogue itself
2906 will be generated after reload, at which point we may not reference
2909 The first passes the exception context to the handler. For this
2910 we use the return value register for a void*.
2912 The second holds the stack pointer value to be restored. For
2913 this we use the static chain register if it exists and is different
2914 from the previous, otherwise some arbitrary call-clobbered register.
2916 The third holds the address of the handler itself. Here we use
2917 some arbitrary call-clobbered register. */
2920 eh_regs (pcontext, psp, pra, outgoing)
2921 rtx *pcontext, *psp, *pra;
2922 int outgoing ATTRIBUTE_UNUSED;
2924 rtx rcontext, rsp, rra;
2927 #ifdef FUNCTION_OUTGOING_VALUE
2929 rcontext = FUNCTION_OUTGOING_VALUE (build_pointer_type (void_type_node),
2930 current_function_decl);
2933 rcontext = FUNCTION_VALUE (build_pointer_type (void_type_node),
2934 current_function_decl);
2936 #ifdef STATIC_CHAIN_REGNUM
2938 rsp = static_chain_incoming_rtx;
2940 rsp = static_chain_rtx;
2941 if (REGNO (rsp) == REGNO (rcontext))
2942 #endif /* STATIC_CHAIN_REGNUM */
2945 if (rsp == NULL_RTX)
2947 for (i = 0; i < FIRST_PSEUDO_REGISTER; ++i)
2948 if (call_used_regs[i] && ! fixed_regs[i] && i != REGNO (rcontext))
2950 if (i == FIRST_PSEUDO_REGISTER)
2953 rsp = gen_rtx_REG (Pmode, i);
2956 for (i = 0; i < FIRST_PSEUDO_REGISTER; ++i)
2957 if (call_used_regs[i] && ! fixed_regs[i]
2958 && i != REGNO (rcontext) && i != REGNO (rsp))
2960 if (i == FIRST_PSEUDO_REGISTER)
2963 rra = gen_rtx_REG (Pmode, i);
2965 *pcontext = rcontext;
2970 /* Retrieve the register which contains the pointer to the eh_context
2971 structure set the __throw. */
2975 get_reg_for_handler ()
2978 reg1 = FUNCTION_VALUE (build_pointer_type (void_type_node),
2979 current_function_decl);
2984 /* Set up the epilogue with the magic bits we'll need to return to the
2985 exception handler. */
2988 expand_builtin_eh_return (context, stack, handler)
2989 tree context, stack, handler;
2991 if (eh_return_context)
2992 error("Duplicate call to __builtin_eh_return");
2995 = copy_to_reg (expand_expr (context, NULL_RTX, VOIDmode, 0));
2996 eh_return_stack_adjust
2997 = copy_to_reg (expand_expr (stack, NULL_RTX, VOIDmode, 0));
2999 = copy_to_reg (expand_expr (handler, NULL_RTX, VOIDmode, 0));
3005 rtx reg1, reg2, reg3;
3006 rtx stub_start, after_stub;
3009 if (!eh_return_context)
3012 current_function_cannot_inline = N_("function uses __builtin_eh_return");
3014 eh_regs (®1, ®2, ®3, 1);
3015 #ifdef POINTERS_EXTEND_UNSIGNED
3016 eh_return_context = convert_memory_address (Pmode, eh_return_context);
3017 eh_return_stack_adjust =
3018 convert_memory_address (Pmode, eh_return_stack_adjust);
3019 eh_return_handler = convert_memory_address (Pmode, eh_return_handler);
3021 emit_move_insn (reg1, eh_return_context);
3022 emit_move_insn (reg2, eh_return_stack_adjust);
3023 emit_move_insn (reg3, eh_return_handler);
3025 /* Talk directly to the target's epilogue code when possible. */
3027 #ifdef HAVE_eh_epilogue
3028 if (HAVE_eh_epilogue)
3030 emit_insn (gen_eh_epilogue (reg1, reg2, reg3));
3035 /* Otherwise, use the same stub technique we had before. */
3037 eh_return_stub_label = stub_start = gen_label_rtx ();
3038 after_stub = gen_label_rtx ();
3040 /* Set the return address to the stub label. */
3042 ra = expand_builtin_return_addr (BUILT_IN_RETURN_ADDRESS,
3043 0, hard_frame_pointer_rtx);
3044 if (GET_CODE (ra) == REG && REGNO (ra) >= FIRST_PSEUDO_REGISTER)
3047 tmp = memory_address (Pmode, gen_rtx_LABEL_REF (Pmode, stub_start));
3048 #ifdef RETURN_ADDR_OFFSET
3049 tmp = plus_constant (tmp, -RETURN_ADDR_OFFSET);
3051 tmp = force_operand (tmp, ra);
3053 emit_move_insn (ra, tmp);
3055 /* Indicate that the registers are in fact used. */
3056 emit_insn (gen_rtx_USE (VOIDmode, reg1));
3057 emit_insn (gen_rtx_USE (VOIDmode, reg2));
3058 emit_insn (gen_rtx_USE (VOIDmode, reg3));
3059 if (GET_CODE (ra) == REG)
3060 emit_insn (gen_rtx_USE (VOIDmode, ra));
3062 /* Generate the stub. */
3064 emit_jump (after_stub);
3065 emit_label (stub_start);
3067 eh_regs (®1, ®2, ®3, 0);
3068 adjust_stack (reg2);
3069 emit_indirect_jump (reg3);
3071 emit_label (after_stub);
3075 /* This contains the code required to verify whether arbitrary instructions
3076 are in the same exception region. */
3078 static int *insn_eh_region = (int *)0;
3079 static int maximum_uid;
3082 set_insn_eh_region (first, region_num)
3089 for (insn = *first; insn; insn = NEXT_INSN (insn))
3091 if ((GET_CODE (insn) == NOTE)
3092 && (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG))
3094 rnum = NOTE_EH_HANDLER (insn);
3095 insn_eh_region[INSN_UID (insn)] = rnum;
3096 insn = NEXT_INSN (insn);
3097 set_insn_eh_region (&insn, rnum);
3098 /* Upon return, insn points to the EH_REGION_END of nested region */
3101 insn_eh_region[INSN_UID (insn)] = region_num;
3102 if ((GET_CODE (insn) == NOTE) &&
3103 (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_END))
3109 /* Free the insn table, an make sure it cannot be used again. */
3112 free_insn_eh_region ()
3119 free (insn_eh_region);
3120 insn_eh_region = (int *)0;
3124 /* Initialize the table. max_uid must be calculated and handed into
3125 this routine. If it is unavailable, passing a value of 0 will
3126 cause this routine to calculate it as well. */
3129 init_insn_eh_region (first, max_uid)
3139 free_insn_eh_region();
3142 for (insn = first; insn; insn = NEXT_INSN (insn))
3143 if (INSN_UID (insn) > max_uid) /* find largest UID */
3144 max_uid = INSN_UID (insn);
3146 maximum_uid = max_uid;
3147 insn_eh_region = (int *) xmalloc ((max_uid + 1) * sizeof (int));
3149 set_insn_eh_region (&insn, 0);
3153 /* Check whether 2 instructions are within the same region. */
3156 in_same_eh_region (insn1, insn2)
3159 int ret, uid1, uid2;
3161 /* If no exceptions, instructions are always in same region. */
3165 /* If the table isn't allocated, assume the worst. */
3166 if (!insn_eh_region)
3169 uid1 = INSN_UID (insn1);
3170 uid2 = INSN_UID (insn2);
3172 /* if instructions have been allocated beyond the end, either
3173 the table is out of date, or this is a late addition, or
3174 something... Assume the worst. */
3175 if (uid1 > maximum_uid || uid2 > maximum_uid)
3178 ret = (insn_eh_region[uid1] == insn_eh_region[uid2]);
3183 /* This function will initialize the handler list for a specified block.
3184 It may recursively call itself if the outer block hasn't been processed
3185 yet. At some point in the future we can trim out handlers which we
3186 know cannot be called. (ie, if a block has an INT type handler,
3187 control will never be passed to an outer INT type handler). */
3189 process_nestinfo (block, info, nested_eh_region)
3191 eh_nesting_info *info;
3192 int *nested_eh_region;
3194 handler_info *ptr, *last_ptr = NULL;
3195 int x, y, count = 0;
3197 handler_info **extra_handlers = 0;
3198 int index = info->region_index[block];
3200 /* If we've already processed this block, simply return. */
3201 if (info->num_handlers[index] > 0)
3204 for (ptr = get_first_handler (block); ptr; last_ptr = ptr, ptr = ptr->next)
3207 /* pick up any information from the next outer region. It will already
3208 contain a summary of itself and all outer regions to it. */
3210 if (nested_eh_region [block] != 0)
3212 int nested_index = info->region_index[nested_eh_region[block]];
3213 process_nestinfo (nested_eh_region[block], info, nested_eh_region);
3214 extra = info->num_handlers[nested_index];
3215 extra_handlers = info->handlers[nested_index];
3216 info->outer_index[index] = nested_index;
3219 /* If the last handler is either a CATCH_ALL or a cleanup, then we
3220 won't use the outer ones since we know control will not go past the
3221 catch-all or cleanup. */
3223 if (last_ptr != NULL && (last_ptr->type_info == NULL
3224 || last_ptr->type_info == CATCH_ALL_TYPE))
3227 info->num_handlers[index] = count + extra;
3228 info->handlers[index] = (handler_info **) xmalloc ((count + extra)
3229 * sizeof (handler_info **));
3231 /* First put all our handlers into the list. */
3232 ptr = get_first_handler (block);
3233 for (x = 0; x < count; x++)
3235 info->handlers[index][x] = ptr;
3239 /* Now add all the outer region handlers, if they aren't they same as
3240 one of the types in the current block. We won't worry about
3241 derived types yet, we'll just look for the exact type. */
3242 for (y =0, x = 0; x < extra ; x++)
3246 /* Check to see if we have a type duplication. */
3247 for (i = 0; i < count; i++)
3248 if (info->handlers[index][i]->type_info == extra_handlers[x]->type_info)
3251 /* Record one less handler. */
3252 (info->num_handlers[index])--;
3257 info->handlers[index][y + count] = extra_handlers[x];
3263 /* This function will allocate and initialize an eh_nesting_info structure.
3264 It returns a pointer to the completed data structure. If there are
3265 no exception regions, a NULL value is returned. */
3267 init_eh_nesting_info ()
3269 int *nested_eh_region;
3270 int region_count = 0;
3271 rtx eh_note = NULL_RTX;
3272 eh_nesting_info *info;
3276 info = (eh_nesting_info *) xmalloc (sizeof (eh_nesting_info));
3277 info->region_index = (int *) xcalloc ((max_label_num () + 1), sizeof (int));
3278 nested_eh_region = (int *) xcalloc (max_label_num () + 1, sizeof (int));
3280 /* Create the nested_eh_region list. If indexed with a block number, it
3281 returns the block number of the next outermost region, if any.
3282 We can count the number of regions and initialize the region_index
3283 vector at the same time. */
3284 for (insn = get_insns(); insn; insn = NEXT_INSN (insn))
3286 if (GET_CODE (insn) == NOTE)
3288 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_BEG)
3290 int block = NOTE_EH_HANDLER (insn);
3292 info->region_index[block] = region_count;
3294 nested_eh_region [block] =
3295 NOTE_EH_HANDLER (XEXP (eh_note, 0));
3297 nested_eh_region [block] = 0;
3298 eh_note = gen_rtx_EXPR_LIST (VOIDmode, insn, eh_note);
3300 else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_EH_REGION_END)
3301 eh_note = XEXP (eh_note, 1);
3305 /* If there are no regions, wrap it up now. */
3306 if (region_count == 0)
3308 free (info->region_index);
3310 free (nested_eh_region);
3315 info->handlers = (handler_info ***) xcalloc (region_count,
3316 sizeof (handler_info ***));
3317 info->num_handlers = (int *) xcalloc (region_count, sizeof (int));
3318 info->outer_index = (int *) xcalloc (region_count, sizeof (int));
3320 /* Now initialize the handler lists for all exception blocks. */
3321 for (x = 0; x <= max_label_num (); x++)
3323 if (info->region_index[x] != 0)
3324 process_nestinfo (x, info, nested_eh_region);
3326 info->region_count = region_count;
3329 free (nested_eh_region);
3335 /* This function is used to retreive the vector of handlers which
3336 can be reached by a given insn in a given exception region.
3337 BLOCK is the exception block the insn is in.
3338 INFO is the eh_nesting_info structure.
3339 INSN is the (optional) insn within the block. If insn is not NULL_RTX,
3340 it may contain reg notes which modify its throwing behavior, and
3341 these will be obeyed. If NULL_RTX is passed, then we simply return the
3343 HANDLERS is the address of a pointer to a vector of handler_info pointers.
3344 Upon return, this will have the handlers which can be reached by block.
3345 This function returns the number of elements in the handlers vector. */
3347 reachable_handlers (block, info, insn, handlers)
3349 eh_nesting_info *info;
3351 handler_info ***handlers;
3359 index = info->region_index[block];
3361 if (insn && GET_CODE (insn) == CALL_INSN)
3363 /* RETHROWs specify a region number from which we are going to rethrow.
3364 This means we won't pass control to handlers in the specified
3365 region, but rather any region OUTSIDE the specified region.
3366 We accomplish this by setting block to the outer_index of the
3367 specified region. */
3368 rtx note = find_reg_note (insn, REG_EH_RETHROW, NULL_RTX);
3371 index = eh_region_from_symbol (XEXP (note, 0));
3372 index = info->region_index[index];
3374 index = info->outer_index[index];
3378 /* If there is no rethrow, we look for a REG_EH_REGION, and
3379 we'll throw from that block. A value of 0 or less
3380 indicates that this insn cannot throw. */
3381 note = find_reg_note (insn, REG_EH_REGION, NULL_RTX);
3384 int b = XINT (XEXP (note, 0), 0);
3388 index = info->region_index[b];
3392 /* If we reach this point, and index is 0, there is no throw. */
3396 *handlers = info->handlers[index];
3397 return info->num_handlers[index];
3401 /* This function will free all memory associated with the eh_nesting info. */
3404 free_eh_nesting_info (info)
3405 eh_nesting_info *info;
3410 if (info->region_index)
3411 free (info->region_index);
3412 if (info->num_handlers)
3413 free (info->num_handlers);
3414 if (info->outer_index)
3415 free (info->outer_index);
3418 for (x = 0; x < info->region_count; x++)
3419 if (info->handlers[x])
3420 free (info->handlers[x]);
3421 free (info->handlers);