Daily bump.
[official-gcc.git] / gcc / tree-eh.c
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1 /* Exception handling semantics and decomposition for trees.
2 Copyright (C) 2003-2018 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 3, or (at your option)
9 any later version.
11 GCC is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING3. If not see
18 <http://www.gnu.org/licenses/>. */
20 #include "config.h"
21 #include "system.h"
22 #include "coretypes.h"
23 #include "backend.h"
24 #include "rtl.h"
25 #include "tree.h"
26 #include "gimple.h"
27 #include "cfghooks.h"
28 #include "tree-pass.h"
29 #include "ssa.h"
30 #include "cgraph.h"
31 #include "diagnostic-core.h"
32 #include "fold-const.h"
33 #include "calls.h"
34 #include "except.h"
35 #include "cfganal.h"
36 #include "cfgcleanup.h"
37 #include "tree-eh.h"
38 #include "gimple-iterator.h"
39 #include "tree-cfg.h"
40 #include "tree-into-ssa.h"
41 #include "tree-ssa.h"
42 #include "tree-inline.h"
43 #include "langhooks.h"
44 #include "cfgloop.h"
45 #include "gimple-low.h"
46 #include "stringpool.h"
47 #include "attribs.h"
48 #include "asan.h"
49 #include "gimplify.h"
51 /* In some instances a tree and a gimple need to be stored in a same table,
52 i.e. in hash tables. This is a structure to do this. */
53 typedef union {tree *tp; tree t; gimple *g;} treemple;
55 /* Misc functions used in this file. */
57 /* Remember and lookup EH landing pad data for arbitrary statements.
58 Really this means any statement that could_throw_p. We could
59 stuff this information into the stmt_ann data structure, but:
61 (1) We absolutely rely on this information being kept until
62 we get to rtl. Once we're done with lowering here, if we lose
63 the information there's no way to recover it!
65 (2) There are many more statements that *cannot* throw as
66 compared to those that can. We should be saving some amount
67 of space by only allocating memory for those that can throw. */
69 /* Add statement T in function IFUN to landing pad NUM. */
71 static void
72 add_stmt_to_eh_lp_fn (struct function *ifun, gimple *t, int num)
74 gcc_assert (num != 0);
76 if (!get_eh_throw_stmt_table (ifun))
77 set_eh_throw_stmt_table (ifun, hash_map<gimple *, int>::create_ggc (31));
79 gcc_assert (!get_eh_throw_stmt_table (ifun)->put (t, num));
82 /* Add statement T in the current function (cfun) to EH landing pad NUM. */
84 void
85 add_stmt_to_eh_lp (gimple *t, int num)
87 add_stmt_to_eh_lp_fn (cfun, t, num);
90 /* Add statement T to the single EH landing pad in REGION. */
92 static void
93 record_stmt_eh_region (eh_region region, gimple *t)
95 if (region == NULL)
96 return;
97 if (region->type == ERT_MUST_NOT_THROW)
98 add_stmt_to_eh_lp_fn (cfun, t, -region->index);
99 else
101 eh_landing_pad lp = region->landing_pads;
102 if (lp == NULL)
103 lp = gen_eh_landing_pad (region);
104 else
105 gcc_assert (lp->next_lp == NULL);
106 add_stmt_to_eh_lp_fn (cfun, t, lp->index);
111 /* Remove statement T in function IFUN from its EH landing pad. */
113 bool
114 remove_stmt_from_eh_lp_fn (struct function *ifun, gimple *t)
116 if (!get_eh_throw_stmt_table (ifun))
117 return false;
119 if (!get_eh_throw_stmt_table (ifun)->get (t))
120 return false;
122 get_eh_throw_stmt_table (ifun)->remove (t);
123 return true;
127 /* Remove statement T in the current function (cfun) from its
128 EH landing pad. */
130 bool
131 remove_stmt_from_eh_lp (gimple *t)
133 return remove_stmt_from_eh_lp_fn (cfun, t);
136 /* Determine if statement T is inside an EH region in function IFUN.
137 Positive numbers indicate a landing pad index; negative numbers
138 indicate a MUST_NOT_THROW region index; zero indicates that the
139 statement is not recorded in the region table. */
142 lookup_stmt_eh_lp_fn (struct function *ifun, gimple *t)
144 if (ifun->eh->throw_stmt_table == NULL)
145 return 0;
147 int *lp_nr = ifun->eh->throw_stmt_table->get (t);
148 return lp_nr ? *lp_nr : 0;
151 /* Likewise, but always use the current function. */
154 lookup_stmt_eh_lp (gimple *t)
156 /* We can get called from initialized data when -fnon-call-exceptions
157 is on; prevent crash. */
158 if (!cfun)
159 return 0;
160 return lookup_stmt_eh_lp_fn (cfun, t);
163 /* First pass of EH node decomposition. Build up a tree of GIMPLE_TRY_FINALLY
164 nodes and LABEL_DECL nodes. We will use this during the second phase to
165 determine if a goto leaves the body of a TRY_FINALLY_EXPR node. */
167 struct finally_tree_node
169 /* When storing a GIMPLE_TRY, we have to record a gimple. However
170 when deciding whether a GOTO to a certain LABEL_DECL (which is a
171 tree) leaves the TRY block, its necessary to record a tree in
172 this field. Thus a treemple is used. */
173 treemple child;
174 gtry *parent;
177 /* Hashtable helpers. */
179 struct finally_tree_hasher : free_ptr_hash <finally_tree_node>
181 static inline hashval_t hash (const finally_tree_node *);
182 static inline bool equal (const finally_tree_node *,
183 const finally_tree_node *);
186 inline hashval_t
187 finally_tree_hasher::hash (const finally_tree_node *v)
189 return (intptr_t)v->child.t >> 4;
192 inline bool
193 finally_tree_hasher::equal (const finally_tree_node *v,
194 const finally_tree_node *c)
196 return v->child.t == c->child.t;
199 /* Note that this table is *not* marked GTY. It is short-lived. */
200 static hash_table<finally_tree_hasher> *finally_tree;
202 static void
203 record_in_finally_tree (treemple child, gtry *parent)
205 struct finally_tree_node *n;
206 finally_tree_node **slot;
208 n = XNEW (struct finally_tree_node);
209 n->child = child;
210 n->parent = parent;
212 slot = finally_tree->find_slot (n, INSERT);
213 gcc_assert (!*slot);
214 *slot = n;
217 static void
218 collect_finally_tree (gimple *stmt, gtry *region);
220 /* Go through the gimple sequence. Works with collect_finally_tree to
221 record all GIMPLE_LABEL and GIMPLE_TRY statements. */
223 static void
224 collect_finally_tree_1 (gimple_seq seq, gtry *region)
226 gimple_stmt_iterator gsi;
228 for (gsi = gsi_start (seq); !gsi_end_p (gsi); gsi_next (&gsi))
229 collect_finally_tree (gsi_stmt (gsi), region);
232 static void
233 collect_finally_tree (gimple *stmt, gtry *region)
235 treemple temp;
237 switch (gimple_code (stmt))
239 case GIMPLE_LABEL:
240 temp.t = gimple_label_label (as_a <glabel *> (stmt));
241 record_in_finally_tree (temp, region);
242 break;
244 case GIMPLE_TRY:
245 if (gimple_try_kind (stmt) == GIMPLE_TRY_FINALLY)
247 temp.g = stmt;
248 record_in_finally_tree (temp, region);
249 collect_finally_tree_1 (gimple_try_eval (stmt),
250 as_a <gtry *> (stmt));
251 collect_finally_tree_1 (gimple_try_cleanup (stmt), region);
253 else if (gimple_try_kind (stmt) == GIMPLE_TRY_CATCH)
255 collect_finally_tree_1 (gimple_try_eval (stmt), region);
256 collect_finally_tree_1 (gimple_try_cleanup (stmt), region);
258 break;
260 case GIMPLE_CATCH:
261 collect_finally_tree_1 (gimple_catch_handler (
262 as_a <gcatch *> (stmt)),
263 region);
264 break;
266 case GIMPLE_EH_FILTER:
267 collect_finally_tree_1 (gimple_eh_filter_failure (stmt), region);
268 break;
270 case GIMPLE_EH_ELSE:
272 geh_else *eh_else_stmt = as_a <geh_else *> (stmt);
273 collect_finally_tree_1 (gimple_eh_else_n_body (eh_else_stmt), region);
274 collect_finally_tree_1 (gimple_eh_else_e_body (eh_else_stmt), region);
276 break;
278 default:
279 /* A type, a decl, or some kind of statement that we're not
280 interested in. Don't walk them. */
281 break;
286 /* Use the finally tree to determine if a jump from START to TARGET
287 would leave the try_finally node that START lives in. */
289 static bool
290 outside_finally_tree (treemple start, gimple *target)
292 struct finally_tree_node n, *p;
296 n.child = start;
297 p = finally_tree->find (&n);
298 if (!p)
299 return true;
300 start.g = p->parent;
302 while (start.g != target);
304 return false;
307 /* Second pass of EH node decomposition. Actually transform the GIMPLE_TRY
308 nodes into a set of gotos, magic labels, and eh regions.
309 The eh region creation is straight-forward, but frobbing all the gotos
310 and such into shape isn't. */
312 /* The sequence into which we record all EH stuff. This will be
313 placed at the end of the function when we're all done. */
314 static gimple_seq eh_seq;
316 /* Record whether an EH region contains something that can throw,
317 indexed by EH region number. */
318 static bitmap eh_region_may_contain_throw_map;
320 /* The GOTO_QUEUE is an array of GIMPLE_GOTO and GIMPLE_RETURN
321 statements that are seen to escape this GIMPLE_TRY_FINALLY node.
322 The idea is to record a gimple statement for everything except for
323 the conditionals, which get their labels recorded. Since labels are
324 of type 'tree', we need this node to store both gimple and tree
325 objects. REPL_STMT is the sequence used to replace the goto/return
326 statement. CONT_STMT is used to store the statement that allows
327 the return/goto to jump to the original destination. */
329 struct goto_queue_node
331 treemple stmt;
332 location_t location;
333 gimple_seq repl_stmt;
334 gimple *cont_stmt;
335 int index;
336 /* This is used when index >= 0 to indicate that stmt is a label (as
337 opposed to a goto stmt). */
338 int is_label;
341 /* State of the world while lowering. */
343 struct leh_state
345 /* What's "current" while constructing the eh region tree. These
346 correspond to variables of the same name in cfun->eh, which we
347 don't have easy access to. */
348 eh_region cur_region;
350 /* What's "current" for the purposes of __builtin_eh_pointer. For
351 a CATCH, this is the associated TRY. For an EH_FILTER, this is
352 the associated ALLOWED_EXCEPTIONS, etc. */
353 eh_region ehp_region;
355 /* Processing of TRY_FINALLY requires a bit more state. This is
356 split out into a separate structure so that we don't have to
357 copy so much when processing other nodes. */
358 struct leh_tf_state *tf;
361 struct leh_tf_state
363 /* Pointer to the GIMPLE_TRY_FINALLY node under discussion. The
364 try_finally_expr is the original GIMPLE_TRY_FINALLY. We need to retain
365 this so that outside_finally_tree can reliably reference the tree used
366 in the collect_finally_tree data structures. */
367 gtry *try_finally_expr;
368 gtry *top_p;
370 /* While lowering a top_p usually it is expanded into multiple statements,
371 thus we need the following field to store them. */
372 gimple_seq top_p_seq;
374 /* The state outside this try_finally node. */
375 struct leh_state *outer;
377 /* The exception region created for it. */
378 eh_region region;
380 /* The goto queue. */
381 struct goto_queue_node *goto_queue;
382 size_t goto_queue_size;
383 size_t goto_queue_active;
385 /* Pointer map to help in searching goto_queue when it is large. */
386 hash_map<gimple *, goto_queue_node *> *goto_queue_map;
388 /* The set of unique labels seen as entries in the goto queue. */
389 vec<tree> dest_array;
391 /* A label to be added at the end of the completed transformed
392 sequence. It will be set if may_fallthru was true *at one time*,
393 though subsequent transformations may have cleared that flag. */
394 tree fallthru_label;
396 /* True if it is possible to fall out the bottom of the try block.
397 Cleared if the fallthru is converted to a goto. */
398 bool may_fallthru;
400 /* True if any entry in goto_queue is a GIMPLE_RETURN. */
401 bool may_return;
403 /* True if the finally block can receive an exception edge.
404 Cleared if the exception case is handled by code duplication. */
405 bool may_throw;
408 static gimple_seq lower_eh_must_not_throw (struct leh_state *, gtry *);
410 /* Search for STMT in the goto queue. Return the replacement,
411 or null if the statement isn't in the queue. */
413 #define LARGE_GOTO_QUEUE 20
415 static void lower_eh_constructs_1 (struct leh_state *state, gimple_seq *seq);
417 static gimple_seq
418 find_goto_replacement (struct leh_tf_state *tf, treemple stmt)
420 unsigned int i;
422 if (tf->goto_queue_active < LARGE_GOTO_QUEUE)
424 for (i = 0; i < tf->goto_queue_active; i++)
425 if ( tf->goto_queue[i].stmt.g == stmt.g)
426 return tf->goto_queue[i].repl_stmt;
427 return NULL;
430 /* If we have a large number of entries in the goto_queue, create a
431 pointer map and use that for searching. */
433 if (!tf->goto_queue_map)
435 tf->goto_queue_map = new hash_map<gimple *, goto_queue_node *>;
436 for (i = 0; i < tf->goto_queue_active; i++)
438 bool existed = tf->goto_queue_map->put (tf->goto_queue[i].stmt.g,
439 &tf->goto_queue[i]);
440 gcc_assert (!existed);
444 goto_queue_node **slot = tf->goto_queue_map->get (stmt.g);
445 if (slot != NULL)
446 return ((*slot)->repl_stmt);
448 return NULL;
451 /* A subroutine of replace_goto_queue_1. Handles the sub-clauses of a
452 lowered GIMPLE_COND. If, by chance, the replacement is a simple goto,
453 then we can just splat it in, otherwise we add the new stmts immediately
454 after the GIMPLE_COND and redirect. */
456 static void
457 replace_goto_queue_cond_clause (tree *tp, struct leh_tf_state *tf,
458 gimple_stmt_iterator *gsi)
460 tree label;
461 gimple_seq new_seq;
462 treemple temp;
463 location_t loc = gimple_location (gsi_stmt (*gsi));
465 temp.tp = tp;
466 new_seq = find_goto_replacement (tf, temp);
467 if (!new_seq)
468 return;
470 if (gimple_seq_singleton_p (new_seq)
471 && gimple_code (gimple_seq_first_stmt (new_seq)) == GIMPLE_GOTO)
473 *tp = gimple_goto_dest (gimple_seq_first_stmt (new_seq));
474 return;
477 label = create_artificial_label (loc);
478 /* Set the new label for the GIMPLE_COND */
479 *tp = label;
481 gsi_insert_after (gsi, gimple_build_label (label), GSI_CONTINUE_LINKING);
482 gsi_insert_seq_after (gsi, gimple_seq_copy (new_seq), GSI_CONTINUE_LINKING);
485 /* The real work of replace_goto_queue. Returns with TSI updated to
486 point to the next statement. */
488 static void replace_goto_queue_stmt_list (gimple_seq *, struct leh_tf_state *);
490 static void
491 replace_goto_queue_1 (gimple *stmt, struct leh_tf_state *tf,
492 gimple_stmt_iterator *gsi)
494 gimple_seq seq;
495 treemple temp;
496 temp.g = NULL;
498 switch (gimple_code (stmt))
500 case GIMPLE_GOTO:
501 case GIMPLE_RETURN:
502 temp.g = stmt;
503 seq = find_goto_replacement (tf, temp);
504 if (seq)
506 gsi_insert_seq_before (gsi, gimple_seq_copy (seq), GSI_SAME_STMT);
507 gsi_remove (gsi, false);
508 return;
510 break;
512 case GIMPLE_COND:
513 replace_goto_queue_cond_clause (gimple_op_ptr (stmt, 2), tf, gsi);
514 replace_goto_queue_cond_clause (gimple_op_ptr (stmt, 3), tf, gsi);
515 break;
517 case GIMPLE_TRY:
518 replace_goto_queue_stmt_list (gimple_try_eval_ptr (stmt), tf);
519 replace_goto_queue_stmt_list (gimple_try_cleanup_ptr (stmt), tf);
520 break;
521 case GIMPLE_CATCH:
522 replace_goto_queue_stmt_list (gimple_catch_handler_ptr (
523 as_a <gcatch *> (stmt)),
524 tf);
525 break;
526 case GIMPLE_EH_FILTER:
527 replace_goto_queue_stmt_list (gimple_eh_filter_failure_ptr (stmt), tf);
528 break;
529 case GIMPLE_EH_ELSE:
531 geh_else *eh_else_stmt = as_a <geh_else *> (stmt);
532 replace_goto_queue_stmt_list (gimple_eh_else_n_body_ptr (eh_else_stmt),
533 tf);
534 replace_goto_queue_stmt_list (gimple_eh_else_e_body_ptr (eh_else_stmt),
535 tf);
537 break;
539 default:
540 /* These won't have gotos in them. */
541 break;
544 gsi_next (gsi);
547 /* A subroutine of replace_goto_queue. Handles GIMPLE_SEQ. */
549 static void
550 replace_goto_queue_stmt_list (gimple_seq *seq, struct leh_tf_state *tf)
552 gimple_stmt_iterator gsi = gsi_start (*seq);
554 while (!gsi_end_p (gsi))
555 replace_goto_queue_1 (gsi_stmt (gsi), tf, &gsi);
558 /* Replace all goto queue members. */
560 static void
561 replace_goto_queue (struct leh_tf_state *tf)
563 if (tf->goto_queue_active == 0)
564 return;
565 replace_goto_queue_stmt_list (&tf->top_p_seq, tf);
566 replace_goto_queue_stmt_list (&eh_seq, tf);
569 /* Add a new record to the goto queue contained in TF. NEW_STMT is the
570 data to be added, IS_LABEL indicates whether NEW_STMT is a label or
571 a gimple return. */
573 static void
574 record_in_goto_queue (struct leh_tf_state *tf,
575 treemple new_stmt,
576 int index,
577 bool is_label,
578 location_t location)
580 size_t active, size;
581 struct goto_queue_node *q;
583 gcc_assert (!tf->goto_queue_map);
585 active = tf->goto_queue_active;
586 size = tf->goto_queue_size;
587 if (active >= size)
589 size = (size ? size * 2 : 32);
590 tf->goto_queue_size = size;
591 tf->goto_queue
592 = XRESIZEVEC (struct goto_queue_node, tf->goto_queue, size);
595 q = &tf->goto_queue[active];
596 tf->goto_queue_active = active + 1;
598 memset (q, 0, sizeof (*q));
599 q->stmt = new_stmt;
600 q->index = index;
601 q->location = location;
602 q->is_label = is_label;
605 /* Record the LABEL label in the goto queue contained in TF.
606 TF is not null. */
608 static void
609 record_in_goto_queue_label (struct leh_tf_state *tf, treemple stmt, tree label,
610 location_t location)
612 int index;
613 treemple temp, new_stmt;
615 if (!label)
616 return;
618 /* Computed and non-local gotos do not get processed. Given
619 their nature we can neither tell whether we've escaped the
620 finally block nor redirect them if we knew. */
621 if (TREE_CODE (label) != LABEL_DECL)
622 return;
624 /* No need to record gotos that don't leave the try block. */
625 temp.t = label;
626 if (!outside_finally_tree (temp, tf->try_finally_expr))
627 return;
629 if (! tf->dest_array.exists ())
631 tf->dest_array.create (10);
632 tf->dest_array.quick_push (label);
633 index = 0;
635 else
637 int n = tf->dest_array.length ();
638 for (index = 0; index < n; ++index)
639 if (tf->dest_array[index] == label)
640 break;
641 if (index == n)
642 tf->dest_array.safe_push (label);
645 /* In the case of a GOTO we want to record the destination label,
646 since with a GIMPLE_COND we have an easy access to the then/else
647 labels. */
648 new_stmt = stmt;
649 record_in_goto_queue (tf, new_stmt, index, true, location);
652 /* For any GIMPLE_GOTO or GIMPLE_RETURN, decide whether it leaves a try_finally
653 node, and if so record that fact in the goto queue associated with that
654 try_finally node. */
656 static void
657 maybe_record_in_goto_queue (struct leh_state *state, gimple *stmt)
659 struct leh_tf_state *tf = state->tf;
660 treemple new_stmt;
662 if (!tf)
663 return;
665 switch (gimple_code (stmt))
667 case GIMPLE_COND:
669 gcond *cond_stmt = as_a <gcond *> (stmt);
670 new_stmt.tp = gimple_op_ptr (cond_stmt, 2);
671 record_in_goto_queue_label (tf, new_stmt,
672 gimple_cond_true_label (cond_stmt),
673 EXPR_LOCATION (*new_stmt.tp));
674 new_stmt.tp = gimple_op_ptr (cond_stmt, 3);
675 record_in_goto_queue_label (tf, new_stmt,
676 gimple_cond_false_label (cond_stmt),
677 EXPR_LOCATION (*new_stmt.tp));
679 break;
680 case GIMPLE_GOTO:
681 new_stmt.g = stmt;
682 record_in_goto_queue_label (tf, new_stmt, gimple_goto_dest (stmt),
683 gimple_location (stmt));
684 break;
686 case GIMPLE_RETURN:
687 tf->may_return = true;
688 new_stmt.g = stmt;
689 record_in_goto_queue (tf, new_stmt, -1, false, gimple_location (stmt));
690 break;
692 default:
693 gcc_unreachable ();
698 #if CHECKING_P
699 /* We do not process GIMPLE_SWITCHes for now. As long as the original source
700 was in fact structured, and we've not yet done jump threading, then none
701 of the labels will leave outer GIMPLE_TRY_FINALLY nodes. Verify this. */
703 static void
704 verify_norecord_switch_expr (struct leh_state *state,
705 gswitch *switch_expr)
707 struct leh_tf_state *tf = state->tf;
708 size_t i, n;
710 if (!tf)
711 return;
713 n = gimple_switch_num_labels (switch_expr);
715 for (i = 0; i < n; ++i)
717 treemple temp;
718 tree lab = CASE_LABEL (gimple_switch_label (switch_expr, i));
719 temp.t = lab;
720 gcc_assert (!outside_finally_tree (temp, tf->try_finally_expr));
723 #else
724 #define verify_norecord_switch_expr(state, switch_expr)
725 #endif
727 /* Redirect a RETURN_EXPR pointed to by Q to FINLAB. If MOD is
728 non-null, insert it before the new branch. */
730 static void
731 do_return_redirection (struct goto_queue_node *q, tree finlab, gimple_seq mod)
733 gimple *x;
735 /* In the case of a return, the queue node must be a gimple statement. */
736 gcc_assert (!q->is_label);
738 /* Note that the return value may have already been computed, e.g.,
740 int x;
741 int foo (void)
743 x = 0;
744 try {
745 return x;
746 } finally {
747 x++;
751 should return 0, not 1. We don't have to do anything to make
752 this happens because the return value has been placed in the
753 RESULT_DECL already. */
755 q->cont_stmt = q->stmt.g;
757 if (mod)
758 gimple_seq_add_seq (&q->repl_stmt, mod);
760 x = gimple_build_goto (finlab);
761 gimple_set_location (x, q->location);
762 gimple_seq_add_stmt (&q->repl_stmt, x);
765 /* Similar, but easier, for GIMPLE_GOTO. */
767 static void
768 do_goto_redirection (struct goto_queue_node *q, tree finlab, gimple_seq mod,
769 struct leh_tf_state *tf)
771 ggoto *x;
773 gcc_assert (q->is_label);
775 q->cont_stmt = gimple_build_goto (tf->dest_array[q->index]);
777 if (mod)
778 gimple_seq_add_seq (&q->repl_stmt, mod);
780 x = gimple_build_goto (finlab);
781 gimple_set_location (x, q->location);
782 gimple_seq_add_stmt (&q->repl_stmt, x);
785 /* Emit a standard landing pad sequence into SEQ for REGION. */
787 static void
788 emit_post_landing_pad (gimple_seq *seq, eh_region region)
790 eh_landing_pad lp = region->landing_pads;
791 glabel *x;
793 if (lp == NULL)
794 lp = gen_eh_landing_pad (region);
796 lp->post_landing_pad = create_artificial_label (UNKNOWN_LOCATION);
797 EH_LANDING_PAD_NR (lp->post_landing_pad) = lp->index;
799 x = gimple_build_label (lp->post_landing_pad);
800 gimple_seq_add_stmt (seq, x);
803 /* Emit a RESX statement into SEQ for REGION. */
805 static void
806 emit_resx (gimple_seq *seq, eh_region region)
808 gresx *x = gimple_build_resx (region->index);
809 gimple_seq_add_stmt (seq, x);
810 if (region->outer)
811 record_stmt_eh_region (region->outer, x);
814 /* Emit an EH_DISPATCH statement into SEQ for REGION. */
816 static void
817 emit_eh_dispatch (gimple_seq *seq, eh_region region)
819 geh_dispatch *x = gimple_build_eh_dispatch (region->index);
820 gimple_seq_add_stmt (seq, x);
823 /* Note that the current EH region may contain a throw, or a
824 call to a function which itself may contain a throw. */
826 static void
827 note_eh_region_may_contain_throw (eh_region region)
829 while (bitmap_set_bit (eh_region_may_contain_throw_map, region->index))
831 if (region->type == ERT_MUST_NOT_THROW)
832 break;
833 region = region->outer;
834 if (region == NULL)
835 break;
839 /* Check if REGION has been marked as containing a throw. If REGION is
840 NULL, this predicate is false. */
842 static inline bool
843 eh_region_may_contain_throw (eh_region r)
845 return r && bitmap_bit_p (eh_region_may_contain_throw_map, r->index);
848 /* We want to transform
849 try { body; } catch { stuff; }
851 normal_sequence:
852 body;
853 over:
854 eh_sequence:
855 landing_pad:
856 stuff;
857 goto over;
859 TP is a GIMPLE_TRY node. REGION is the region whose post_landing_pad
860 should be placed before the second operand, or NULL. OVER is
861 an existing label that should be put at the exit, or NULL. */
863 static gimple_seq
864 frob_into_branch_around (gtry *tp, eh_region region, tree over)
866 gimple *x;
867 gimple_seq cleanup, result;
868 location_t loc = gimple_location (tp);
870 cleanup = gimple_try_cleanup (tp);
871 result = gimple_try_eval (tp);
873 if (region)
874 emit_post_landing_pad (&eh_seq, region);
876 if (gimple_seq_may_fallthru (cleanup))
878 if (!over)
879 over = create_artificial_label (loc);
880 x = gimple_build_goto (over);
881 gimple_set_location (x, loc);
882 gimple_seq_add_stmt (&cleanup, x);
884 gimple_seq_add_seq (&eh_seq, cleanup);
886 if (over)
888 x = gimple_build_label (over);
889 gimple_seq_add_stmt (&result, x);
891 return result;
894 /* A subroutine of lower_try_finally. Duplicate the tree rooted at T.
895 Make sure to record all new labels found. */
897 static gimple_seq
898 lower_try_finally_dup_block (gimple_seq seq, struct leh_state *outer_state,
899 location_t loc)
901 gtry *region = NULL;
902 gimple_seq new_seq;
903 gimple_stmt_iterator gsi;
905 new_seq = copy_gimple_seq_and_replace_locals (seq);
907 for (gsi = gsi_start (new_seq); !gsi_end_p (gsi); gsi_next (&gsi))
909 gimple *stmt = gsi_stmt (gsi);
910 /* We duplicate __builtin_stack_restore at -O0 in the hope of eliminating
911 it on the EH paths. When it is not eliminated, make it transparent in
912 the debug info. */
913 if (gimple_call_builtin_p (stmt, BUILT_IN_STACK_RESTORE))
914 gimple_set_location (stmt, UNKNOWN_LOCATION);
915 else if (LOCATION_LOCUS (gimple_location (stmt)) == UNKNOWN_LOCATION)
917 tree block = gimple_block (stmt);
918 gimple_set_location (stmt, loc);
919 gimple_set_block (stmt, block);
923 if (outer_state->tf)
924 region = outer_state->tf->try_finally_expr;
925 collect_finally_tree_1 (new_seq, region);
927 return new_seq;
930 /* A subroutine of lower_try_finally. Create a fallthru label for
931 the given try_finally state. The only tricky bit here is that
932 we have to make sure to record the label in our outer context. */
934 static tree
935 lower_try_finally_fallthru_label (struct leh_tf_state *tf)
937 tree label = tf->fallthru_label;
938 treemple temp;
940 if (!label)
942 label = create_artificial_label (gimple_location (tf->try_finally_expr));
943 tf->fallthru_label = label;
944 if (tf->outer->tf)
946 temp.t = label;
947 record_in_finally_tree (temp, tf->outer->tf->try_finally_expr);
950 return label;
953 /* A subroutine of lower_try_finally. If FINALLY consits of a
954 GIMPLE_EH_ELSE node, return it. */
956 static inline geh_else *
957 get_eh_else (gimple_seq finally)
959 gimple *x = gimple_seq_first_stmt (finally);
960 if (gimple_code (x) == GIMPLE_EH_ELSE)
962 gcc_assert (gimple_seq_singleton_p (finally));
963 return as_a <geh_else *> (x);
965 return NULL;
968 /* A subroutine of lower_try_finally. If the eh_protect_cleanup_actions
969 langhook returns non-null, then the language requires that the exception
970 path out of a try_finally be treated specially. To wit: the code within
971 the finally block may not itself throw an exception. We have two choices
972 here. First we can duplicate the finally block and wrap it in a
973 must_not_throw region. Second, we can generate code like
975 try {
976 finally_block;
977 } catch {
978 if (fintmp == eh_edge)
979 protect_cleanup_actions;
982 where "fintmp" is the temporary used in the switch statement generation
983 alternative considered below. For the nonce, we always choose the first
984 option.
986 THIS_STATE may be null if this is a try-cleanup, not a try-finally. */
988 static void
989 honor_protect_cleanup_actions (struct leh_state *outer_state,
990 struct leh_state *this_state,
991 struct leh_tf_state *tf)
993 gimple_seq finally = gimple_try_cleanup (tf->top_p);
995 /* EH_ELSE doesn't come from user code; only compiler generated stuff.
996 It does need to be handled here, so as to separate the (different)
997 EH path from the normal path. But we should not attempt to wrap
998 it with a must-not-throw node (which indeed gets in the way). */
999 if (geh_else *eh_else = get_eh_else (finally))
1001 gimple_try_set_cleanup (tf->top_p, gimple_eh_else_n_body (eh_else));
1002 finally = gimple_eh_else_e_body (eh_else);
1004 /* Let the ELSE see the exception that's being processed. */
1005 eh_region save_ehp = this_state->ehp_region;
1006 this_state->ehp_region = this_state->cur_region;
1007 lower_eh_constructs_1 (this_state, &finally);
1008 this_state->ehp_region = save_ehp;
1010 else
1012 /* First check for nothing to do. */
1013 if (lang_hooks.eh_protect_cleanup_actions == NULL)
1014 return;
1015 tree actions = lang_hooks.eh_protect_cleanup_actions ();
1016 if (actions == NULL)
1017 return;
1019 if (this_state)
1020 finally = lower_try_finally_dup_block (finally, outer_state,
1021 gimple_location (tf->try_finally_expr));
1023 /* If this cleanup consists of a TRY_CATCH_EXPR with TRY_CATCH_IS_CLEANUP
1024 set, the handler of the TRY_CATCH_EXPR is another cleanup which ought
1025 to be in an enclosing scope, but needs to be implemented at this level
1026 to avoid a nesting violation (see wrap_temporary_cleanups in
1027 cp/decl.c). Since it's logically at an outer level, we should call
1028 terminate before we get to it, so strip it away before adding the
1029 MUST_NOT_THROW filter. */
1030 gimple_stmt_iterator gsi = gsi_start (finally);
1031 gimple *x = gsi_stmt (gsi);
1032 if (gimple_code (x) == GIMPLE_TRY
1033 && gimple_try_kind (x) == GIMPLE_TRY_CATCH
1034 && gimple_try_catch_is_cleanup (x))
1036 gsi_insert_seq_before (&gsi, gimple_try_eval (x), GSI_SAME_STMT);
1037 gsi_remove (&gsi, false);
1040 /* Wrap the block with protect_cleanup_actions as the action. */
1041 geh_mnt *eh_mnt = gimple_build_eh_must_not_throw (actions);
1042 gtry *try_stmt = gimple_build_try (finally,
1043 gimple_seq_alloc_with_stmt (eh_mnt),
1044 GIMPLE_TRY_CATCH);
1045 finally = lower_eh_must_not_throw (outer_state, try_stmt);
1048 /* Drop all of this into the exception sequence. */
1049 emit_post_landing_pad (&eh_seq, tf->region);
1050 gimple_seq_add_seq (&eh_seq, finally);
1051 if (gimple_seq_may_fallthru (finally))
1052 emit_resx (&eh_seq, tf->region);
1054 /* Having now been handled, EH isn't to be considered with
1055 the rest of the outgoing edges. */
1056 tf->may_throw = false;
1059 /* A subroutine of lower_try_finally. We have determined that there is
1060 no fallthru edge out of the finally block. This means that there is
1061 no outgoing edge corresponding to any incoming edge. Restructure the
1062 try_finally node for this special case. */
1064 static void
1065 lower_try_finally_nofallthru (struct leh_state *state,
1066 struct leh_tf_state *tf)
1068 tree lab;
1069 gimple *x;
1070 geh_else *eh_else;
1071 gimple_seq finally;
1072 struct goto_queue_node *q, *qe;
1074 lab = create_artificial_label (gimple_location (tf->try_finally_expr));
1076 /* We expect that tf->top_p is a GIMPLE_TRY. */
1077 finally = gimple_try_cleanup (tf->top_p);
1078 tf->top_p_seq = gimple_try_eval (tf->top_p);
1080 x = gimple_build_label (lab);
1081 gimple_seq_add_stmt (&tf->top_p_seq, x);
1083 q = tf->goto_queue;
1084 qe = q + tf->goto_queue_active;
1085 for (; q < qe; ++q)
1086 if (q->index < 0)
1087 do_return_redirection (q, lab, NULL);
1088 else
1089 do_goto_redirection (q, lab, NULL, tf);
1091 replace_goto_queue (tf);
1093 /* Emit the finally block into the stream. Lower EH_ELSE at this time. */
1094 eh_else = get_eh_else (finally);
1095 if (eh_else)
1097 finally = gimple_eh_else_n_body (eh_else);
1098 lower_eh_constructs_1 (state, &finally);
1099 gimple_seq_add_seq (&tf->top_p_seq, finally);
1101 if (tf->may_throw)
1103 finally = gimple_eh_else_e_body (eh_else);
1104 lower_eh_constructs_1 (state, &finally);
1106 emit_post_landing_pad (&eh_seq, tf->region);
1107 gimple_seq_add_seq (&eh_seq, finally);
1110 else
1112 lower_eh_constructs_1 (state, &finally);
1113 gimple_seq_add_seq (&tf->top_p_seq, finally);
1115 if (tf->may_throw)
1117 emit_post_landing_pad (&eh_seq, tf->region);
1119 x = gimple_build_goto (lab);
1120 gimple_set_location (x, gimple_location (tf->try_finally_expr));
1121 gimple_seq_add_stmt (&eh_seq, x);
1126 /* A subroutine of lower_try_finally. We have determined that there is
1127 exactly one destination of the finally block. Restructure the
1128 try_finally node for this special case. */
1130 static void
1131 lower_try_finally_onedest (struct leh_state *state, struct leh_tf_state *tf)
1133 struct goto_queue_node *q, *qe;
1134 geh_else *eh_else;
1135 glabel *label_stmt;
1136 gimple *x;
1137 gimple_seq finally;
1138 gimple_stmt_iterator gsi;
1139 tree finally_label;
1140 location_t loc = gimple_location (tf->try_finally_expr);
1142 finally = gimple_try_cleanup (tf->top_p);
1143 tf->top_p_seq = gimple_try_eval (tf->top_p);
1145 /* Since there's only one destination, and the destination edge can only
1146 either be EH or non-EH, that implies that all of our incoming edges
1147 are of the same type. Therefore we can lower EH_ELSE immediately. */
1148 eh_else = get_eh_else (finally);
1149 if (eh_else)
1151 if (tf->may_throw)
1152 finally = gimple_eh_else_e_body (eh_else);
1153 else
1154 finally = gimple_eh_else_n_body (eh_else);
1157 lower_eh_constructs_1 (state, &finally);
1159 for (gsi = gsi_start (finally); !gsi_end_p (gsi); gsi_next (&gsi))
1161 gimple *stmt = gsi_stmt (gsi);
1162 if (LOCATION_LOCUS (gimple_location (stmt)) == UNKNOWN_LOCATION)
1164 tree block = gimple_block (stmt);
1165 gimple_set_location (stmt, gimple_location (tf->try_finally_expr));
1166 gimple_set_block (stmt, block);
1170 if (tf->may_throw)
1172 /* Only reachable via the exception edge. Add the given label to
1173 the head of the FINALLY block. Append a RESX at the end. */
1174 emit_post_landing_pad (&eh_seq, tf->region);
1175 gimple_seq_add_seq (&eh_seq, finally);
1176 emit_resx (&eh_seq, tf->region);
1177 return;
1180 if (tf->may_fallthru)
1182 /* Only reachable via the fallthru edge. Do nothing but let
1183 the two blocks run together; we'll fall out the bottom. */
1184 gimple_seq_add_seq (&tf->top_p_seq, finally);
1185 return;
1188 finally_label = create_artificial_label (loc);
1189 label_stmt = gimple_build_label (finally_label);
1190 gimple_seq_add_stmt (&tf->top_p_seq, label_stmt);
1192 gimple_seq_add_seq (&tf->top_p_seq, finally);
1194 q = tf->goto_queue;
1195 qe = q + tf->goto_queue_active;
1197 if (tf->may_return)
1199 /* Reachable by return expressions only. Redirect them. */
1200 for (; q < qe; ++q)
1201 do_return_redirection (q, finally_label, NULL);
1202 replace_goto_queue (tf);
1204 else
1206 /* Reachable by goto expressions only. Redirect them. */
1207 for (; q < qe; ++q)
1208 do_goto_redirection (q, finally_label, NULL, tf);
1209 replace_goto_queue (tf);
1211 if (tf->dest_array[0] == tf->fallthru_label)
1213 /* Reachable by goto to fallthru label only. Redirect it
1214 to the new label (already created, sadly), and do not
1215 emit the final branch out, or the fallthru label. */
1216 tf->fallthru_label = NULL;
1217 return;
1221 /* Place the original return/goto to the original destination
1222 immediately after the finally block. */
1223 x = tf->goto_queue[0].cont_stmt;
1224 gimple_seq_add_stmt (&tf->top_p_seq, x);
1225 maybe_record_in_goto_queue (state, x);
1228 /* A subroutine of lower_try_finally. There are multiple edges incoming
1229 and outgoing from the finally block. Implement this by duplicating the
1230 finally block for every destination. */
1232 static void
1233 lower_try_finally_copy (struct leh_state *state, struct leh_tf_state *tf)
1235 gimple_seq finally;
1236 gimple_seq new_stmt;
1237 gimple_seq seq;
1238 gimple *x;
1239 geh_else *eh_else;
1240 tree tmp;
1241 location_t tf_loc = gimple_location (tf->try_finally_expr);
1243 finally = gimple_try_cleanup (tf->top_p);
1245 /* Notice EH_ELSE, and simplify some of the remaining code
1246 by considering FINALLY to be the normal return path only. */
1247 eh_else = get_eh_else (finally);
1248 if (eh_else)
1249 finally = gimple_eh_else_n_body (eh_else);
1251 tf->top_p_seq = gimple_try_eval (tf->top_p);
1252 new_stmt = NULL;
1254 if (tf->may_fallthru)
1256 seq = lower_try_finally_dup_block (finally, state, tf_loc);
1257 lower_eh_constructs_1 (state, &seq);
1258 gimple_seq_add_seq (&new_stmt, seq);
1260 tmp = lower_try_finally_fallthru_label (tf);
1261 x = gimple_build_goto (tmp);
1262 gimple_set_location (x, tf_loc);
1263 gimple_seq_add_stmt (&new_stmt, x);
1266 if (tf->may_throw)
1268 /* We don't need to copy the EH path of EH_ELSE,
1269 since it is only emitted once. */
1270 if (eh_else)
1271 seq = gimple_eh_else_e_body (eh_else);
1272 else
1273 seq = lower_try_finally_dup_block (finally, state, tf_loc);
1274 lower_eh_constructs_1 (state, &seq);
1276 emit_post_landing_pad (&eh_seq, tf->region);
1277 gimple_seq_add_seq (&eh_seq, seq);
1278 emit_resx (&eh_seq, tf->region);
1281 if (tf->goto_queue)
1283 struct goto_queue_node *q, *qe;
1284 int return_index, index;
1285 struct labels_s
1287 struct goto_queue_node *q;
1288 tree label;
1289 } *labels;
1291 return_index = tf->dest_array.length ();
1292 labels = XCNEWVEC (struct labels_s, return_index + 1);
1294 q = tf->goto_queue;
1295 qe = q + tf->goto_queue_active;
1296 for (; q < qe; q++)
1298 index = q->index < 0 ? return_index : q->index;
1300 if (!labels[index].q)
1301 labels[index].q = q;
1304 for (index = 0; index < return_index + 1; index++)
1306 tree lab;
1308 q = labels[index].q;
1309 if (! q)
1310 continue;
1312 lab = labels[index].label
1313 = create_artificial_label (tf_loc);
1315 if (index == return_index)
1316 do_return_redirection (q, lab, NULL);
1317 else
1318 do_goto_redirection (q, lab, NULL, tf);
1320 x = gimple_build_label (lab);
1321 gimple_seq_add_stmt (&new_stmt, x);
1323 seq = lower_try_finally_dup_block (finally, state, q->location);
1324 lower_eh_constructs_1 (state, &seq);
1325 gimple_seq_add_seq (&new_stmt, seq);
1327 gimple_seq_add_stmt (&new_stmt, q->cont_stmt);
1328 maybe_record_in_goto_queue (state, q->cont_stmt);
1331 for (q = tf->goto_queue; q < qe; q++)
1333 tree lab;
1335 index = q->index < 0 ? return_index : q->index;
1337 if (labels[index].q == q)
1338 continue;
1340 lab = labels[index].label;
1342 if (index == return_index)
1343 do_return_redirection (q, lab, NULL);
1344 else
1345 do_goto_redirection (q, lab, NULL, tf);
1348 replace_goto_queue (tf);
1349 free (labels);
1352 /* Need to link new stmts after running replace_goto_queue due
1353 to not wanting to process the same goto stmts twice. */
1354 gimple_seq_add_seq (&tf->top_p_seq, new_stmt);
1357 /* A subroutine of lower_try_finally. There are multiple edges incoming
1358 and outgoing from the finally block. Implement this by instrumenting
1359 each incoming edge and creating a switch statement at the end of the
1360 finally block that branches to the appropriate destination. */
1362 static void
1363 lower_try_finally_switch (struct leh_state *state, struct leh_tf_state *tf)
1365 struct goto_queue_node *q, *qe;
1366 tree finally_tmp, finally_label;
1367 int return_index, eh_index, fallthru_index;
1368 int nlabels, ndests, j, last_case_index;
1369 tree last_case;
1370 auto_vec<tree> case_label_vec;
1371 gimple_seq switch_body = NULL;
1372 gimple *x;
1373 geh_else *eh_else;
1374 tree tmp;
1375 gimple *switch_stmt;
1376 gimple_seq finally;
1377 hash_map<tree, gimple *> *cont_map = NULL;
1378 /* The location of the TRY_FINALLY stmt. */
1379 location_t tf_loc = gimple_location (tf->try_finally_expr);
1380 /* The location of the finally block. */
1381 location_t finally_loc;
1383 finally = gimple_try_cleanup (tf->top_p);
1384 eh_else = get_eh_else (finally);
1386 /* Mash the TRY block to the head of the chain. */
1387 tf->top_p_seq = gimple_try_eval (tf->top_p);
1389 /* The location of the finally is either the last stmt in the finally
1390 block or the location of the TRY_FINALLY itself. */
1391 x = gimple_seq_last_stmt (finally);
1392 finally_loc = x ? gimple_location (x) : tf_loc;
1394 /* Prepare for switch statement generation. */
1395 nlabels = tf->dest_array.length ();
1396 return_index = nlabels;
1397 eh_index = return_index + tf->may_return;
1398 fallthru_index = eh_index + (tf->may_throw && !eh_else);
1399 ndests = fallthru_index + tf->may_fallthru;
1401 finally_tmp = create_tmp_var (integer_type_node, "finally_tmp");
1402 finally_label = create_artificial_label (finally_loc);
1404 /* We use vec::quick_push on case_label_vec throughout this function,
1405 since we know the size in advance and allocate precisely as muce
1406 space as needed. */
1407 case_label_vec.create (ndests);
1408 last_case = NULL;
1409 last_case_index = 0;
1411 /* Begin inserting code for getting to the finally block. Things
1412 are done in this order to correspond to the sequence the code is
1413 laid out. */
1415 if (tf->may_fallthru)
1417 x = gimple_build_assign (finally_tmp,
1418 build_int_cst (integer_type_node,
1419 fallthru_index));
1420 gimple_set_location (x, finally_loc);
1421 gimple_seq_add_stmt (&tf->top_p_seq, x);
1423 tmp = build_int_cst (integer_type_node, fallthru_index);
1424 last_case = build_case_label (tmp, NULL,
1425 create_artificial_label (finally_loc));
1426 case_label_vec.quick_push (last_case);
1427 last_case_index++;
1429 x = gimple_build_label (CASE_LABEL (last_case));
1430 gimple_seq_add_stmt (&switch_body, x);
1432 tmp = lower_try_finally_fallthru_label (tf);
1433 x = gimple_build_goto (tmp);
1434 gimple_set_location (x, finally_loc);
1435 gimple_seq_add_stmt (&switch_body, x);
1438 /* For EH_ELSE, emit the exception path (plus resx) now, then
1439 subsequently we only need consider the normal path. */
1440 if (eh_else)
1442 if (tf->may_throw)
1444 finally = gimple_eh_else_e_body (eh_else);
1445 lower_eh_constructs_1 (state, &finally);
1447 emit_post_landing_pad (&eh_seq, tf->region);
1448 gimple_seq_add_seq (&eh_seq, finally);
1449 emit_resx (&eh_seq, tf->region);
1452 finally = gimple_eh_else_n_body (eh_else);
1454 else if (tf->may_throw)
1456 emit_post_landing_pad (&eh_seq, tf->region);
1458 x = gimple_build_assign (finally_tmp,
1459 build_int_cst (integer_type_node, eh_index));
1460 gimple_seq_add_stmt (&eh_seq, x);
1462 x = gimple_build_goto (finally_label);
1463 gimple_set_location (x, tf_loc);
1464 gimple_seq_add_stmt (&eh_seq, x);
1466 tmp = build_int_cst (integer_type_node, eh_index);
1467 last_case = build_case_label (tmp, NULL,
1468 create_artificial_label (tf_loc));
1469 case_label_vec.quick_push (last_case);
1470 last_case_index++;
1472 x = gimple_build_label (CASE_LABEL (last_case));
1473 gimple_seq_add_stmt (&eh_seq, x);
1474 emit_resx (&eh_seq, tf->region);
1477 x = gimple_build_label (finally_label);
1478 gimple_seq_add_stmt (&tf->top_p_seq, x);
1480 lower_eh_constructs_1 (state, &finally);
1481 gimple_seq_add_seq (&tf->top_p_seq, finally);
1483 /* Redirect each incoming goto edge. */
1484 q = tf->goto_queue;
1485 qe = q + tf->goto_queue_active;
1486 j = last_case_index + tf->may_return;
1487 /* Prepare the assignments to finally_tmp that are executed upon the
1488 entrance through a particular edge. */
1489 for (; q < qe; ++q)
1491 gimple_seq mod = NULL;
1492 int switch_id;
1493 unsigned int case_index;
1495 if (q->index < 0)
1497 x = gimple_build_assign (finally_tmp,
1498 build_int_cst (integer_type_node,
1499 return_index));
1500 gimple_seq_add_stmt (&mod, x);
1501 do_return_redirection (q, finally_label, mod);
1502 switch_id = return_index;
1504 else
1506 x = gimple_build_assign (finally_tmp,
1507 build_int_cst (integer_type_node, q->index));
1508 gimple_seq_add_stmt (&mod, x);
1509 do_goto_redirection (q, finally_label, mod, tf);
1510 switch_id = q->index;
1513 case_index = j + q->index;
1514 if (case_label_vec.length () <= case_index || !case_label_vec[case_index])
1516 tree case_lab;
1517 tmp = build_int_cst (integer_type_node, switch_id);
1518 case_lab = build_case_label (tmp, NULL,
1519 create_artificial_label (tf_loc));
1520 /* We store the cont_stmt in the pointer map, so that we can recover
1521 it in the loop below. */
1522 if (!cont_map)
1523 cont_map = new hash_map<tree, gimple *>;
1524 cont_map->put (case_lab, q->cont_stmt);
1525 case_label_vec.quick_push (case_lab);
1528 for (j = last_case_index; j < last_case_index + nlabels; j++)
1530 gimple *cont_stmt;
1532 last_case = case_label_vec[j];
1534 gcc_assert (last_case);
1535 gcc_assert (cont_map);
1537 cont_stmt = *cont_map->get (last_case);
1539 x = gimple_build_label (CASE_LABEL (last_case));
1540 gimple_seq_add_stmt (&switch_body, x);
1541 gimple_seq_add_stmt (&switch_body, cont_stmt);
1542 maybe_record_in_goto_queue (state, cont_stmt);
1544 if (cont_map)
1545 delete cont_map;
1547 replace_goto_queue (tf);
1549 /* Make sure that the last case is the default label, as one is required.
1550 Then sort the labels, which is also required in GIMPLE. */
1551 CASE_LOW (last_case) = NULL;
1552 tree tem = case_label_vec.pop ();
1553 gcc_assert (tem == last_case);
1554 sort_case_labels (case_label_vec);
1556 /* Build the switch statement, setting last_case to be the default
1557 label. */
1558 switch_stmt = gimple_build_switch (finally_tmp, last_case,
1559 case_label_vec);
1560 gimple_set_location (switch_stmt, finally_loc);
1562 /* Need to link SWITCH_STMT after running replace_goto_queue
1563 due to not wanting to process the same goto stmts twice. */
1564 gimple_seq_add_stmt (&tf->top_p_seq, switch_stmt);
1565 gimple_seq_add_seq (&tf->top_p_seq, switch_body);
1568 /* Decide whether or not we are going to duplicate the finally block.
1569 There are several considerations.
1571 Second, we'd like to prevent egregious code growth. One way to
1572 do this is to estimate the size of the finally block, multiply
1573 that by the number of copies we'd need to make, and compare against
1574 the estimate of the size of the switch machinery we'd have to add. */
1576 static bool
1577 decide_copy_try_finally (int ndests, bool may_throw, gimple_seq finally)
1579 int f_estimate, sw_estimate;
1580 geh_else *eh_else;
1582 /* If there's an EH_ELSE involved, the exception path is separate
1583 and really doesn't come into play for this computation. */
1584 eh_else = get_eh_else (finally);
1585 if (eh_else)
1587 ndests -= may_throw;
1588 finally = gimple_eh_else_n_body (eh_else);
1591 if (!optimize)
1593 gimple_stmt_iterator gsi;
1595 if (ndests == 1)
1596 return true;
1598 for (gsi = gsi_start (finally); !gsi_end_p (gsi); gsi_next (&gsi))
1600 /* Duplicate __builtin_stack_restore in the hope of eliminating it
1601 on the EH paths and, consequently, useless cleanups. */
1602 gimple *stmt = gsi_stmt (gsi);
1603 if (!is_gimple_debug (stmt)
1604 && !gimple_clobber_p (stmt)
1605 && !gimple_call_builtin_p (stmt, BUILT_IN_STACK_RESTORE))
1606 return false;
1608 return true;
1611 /* Finally estimate N times, plus N gotos. */
1612 f_estimate = estimate_num_insns_seq (finally, &eni_size_weights);
1613 f_estimate = (f_estimate + 1) * ndests;
1615 /* Switch statement (cost 10), N variable assignments, N gotos. */
1616 sw_estimate = 10 + 2 * ndests;
1618 /* Optimize for size clearly wants our best guess. */
1619 if (optimize_function_for_size_p (cfun))
1620 return f_estimate < sw_estimate;
1622 /* ??? These numbers are completely made up so far. */
1623 if (optimize > 1)
1624 return f_estimate < 100 || f_estimate < sw_estimate * 2;
1625 else
1626 return f_estimate < 40 || f_estimate * 2 < sw_estimate * 3;
1629 /* REG is the enclosing region for a possible cleanup region, or the region
1630 itself. Returns TRUE if such a region would be unreachable.
1632 Cleanup regions within a must-not-throw region aren't actually reachable
1633 even if there are throwing stmts within them, because the personality
1634 routine will call terminate before unwinding. */
1636 static bool
1637 cleanup_is_dead_in (eh_region reg)
1639 while (reg && reg->type == ERT_CLEANUP)
1640 reg = reg->outer;
1641 return (reg && reg->type == ERT_MUST_NOT_THROW);
1644 /* A subroutine of lower_eh_constructs_1. Lower a GIMPLE_TRY_FINALLY nodes
1645 to a sequence of labels and blocks, plus the exception region trees
1646 that record all the magic. This is complicated by the need to
1647 arrange for the FINALLY block to be executed on all exits. */
1649 static gimple_seq
1650 lower_try_finally (struct leh_state *state, gtry *tp)
1652 struct leh_tf_state this_tf;
1653 struct leh_state this_state;
1654 int ndests;
1655 gimple_seq old_eh_seq;
1657 /* Process the try block. */
1659 memset (&this_tf, 0, sizeof (this_tf));
1660 this_tf.try_finally_expr = tp;
1661 this_tf.top_p = tp;
1662 this_tf.outer = state;
1663 if (using_eh_for_cleanups_p () && !cleanup_is_dead_in (state->cur_region))
1665 this_tf.region = gen_eh_region_cleanup (state->cur_region);
1666 this_state.cur_region = this_tf.region;
1668 else
1670 this_tf.region = NULL;
1671 this_state.cur_region = state->cur_region;
1674 this_state.ehp_region = state->ehp_region;
1675 this_state.tf = &this_tf;
1677 old_eh_seq = eh_seq;
1678 eh_seq = NULL;
1680 lower_eh_constructs_1 (&this_state, gimple_try_eval_ptr (tp));
1682 /* Determine if the try block is escaped through the bottom. */
1683 this_tf.may_fallthru = gimple_seq_may_fallthru (gimple_try_eval (tp));
1685 /* Determine if any exceptions are possible within the try block. */
1686 if (this_tf.region)
1687 this_tf.may_throw = eh_region_may_contain_throw (this_tf.region);
1688 if (this_tf.may_throw)
1689 honor_protect_cleanup_actions (state, &this_state, &this_tf);
1691 /* Determine how many edges (still) reach the finally block. Or rather,
1692 how many destinations are reached by the finally block. Use this to
1693 determine how we process the finally block itself. */
1695 ndests = this_tf.dest_array.length ();
1696 ndests += this_tf.may_fallthru;
1697 ndests += this_tf.may_return;
1698 ndests += this_tf.may_throw;
1700 /* If the FINALLY block is not reachable, dike it out. */
1701 if (ndests == 0)
1703 gimple_seq_add_seq (&this_tf.top_p_seq, gimple_try_eval (tp));
1704 gimple_try_set_cleanup (tp, NULL);
1706 /* If the finally block doesn't fall through, then any destination
1707 we might try to impose there isn't reached either. There may be
1708 some minor amount of cleanup and redirection still needed. */
1709 else if (!gimple_seq_may_fallthru (gimple_try_cleanup (tp)))
1710 lower_try_finally_nofallthru (state, &this_tf);
1712 /* We can easily special-case redirection to a single destination. */
1713 else if (ndests == 1)
1714 lower_try_finally_onedest (state, &this_tf);
1715 else if (decide_copy_try_finally (ndests, this_tf.may_throw,
1716 gimple_try_cleanup (tp)))
1717 lower_try_finally_copy (state, &this_tf);
1718 else
1719 lower_try_finally_switch (state, &this_tf);
1721 /* If someone requested we add a label at the end of the transformed
1722 block, do so. */
1723 if (this_tf.fallthru_label)
1725 /* This must be reached only if ndests == 0. */
1726 gimple *x = gimple_build_label (this_tf.fallthru_label);
1727 gimple_seq_add_stmt (&this_tf.top_p_seq, x);
1730 this_tf.dest_array.release ();
1731 free (this_tf.goto_queue);
1732 if (this_tf.goto_queue_map)
1733 delete this_tf.goto_queue_map;
1735 /* If there was an old (aka outer) eh_seq, append the current eh_seq.
1736 If there was no old eh_seq, then the append is trivially already done. */
1737 if (old_eh_seq)
1739 if (eh_seq == NULL)
1740 eh_seq = old_eh_seq;
1741 else
1743 gimple_seq new_eh_seq = eh_seq;
1744 eh_seq = old_eh_seq;
1745 gimple_seq_add_seq (&eh_seq, new_eh_seq);
1749 return this_tf.top_p_seq;
1752 /* A subroutine of lower_eh_constructs_1. Lower a GIMPLE_TRY_CATCH with a
1753 list of GIMPLE_CATCH to a sequence of labels and blocks, plus the
1754 exception region trees that records all the magic. */
1756 static gimple_seq
1757 lower_catch (struct leh_state *state, gtry *tp)
1759 eh_region try_region = NULL;
1760 struct leh_state this_state = *state;
1761 gimple_stmt_iterator gsi;
1762 tree out_label;
1763 gimple_seq new_seq, cleanup;
1764 gimple *x;
1765 location_t try_catch_loc = gimple_location (tp);
1767 if (flag_exceptions)
1769 try_region = gen_eh_region_try (state->cur_region);
1770 this_state.cur_region = try_region;
1773 lower_eh_constructs_1 (&this_state, gimple_try_eval_ptr (tp));
1775 if (!eh_region_may_contain_throw (try_region))
1776 return gimple_try_eval (tp);
1778 new_seq = NULL;
1779 emit_eh_dispatch (&new_seq, try_region);
1780 emit_resx (&new_seq, try_region);
1782 this_state.cur_region = state->cur_region;
1783 this_state.ehp_region = try_region;
1785 /* Add eh_seq from lowering EH in the cleanup sequence after the cleanup
1786 itself, so that e.g. for coverage purposes the nested cleanups don't
1787 appear before the cleanup body. See PR64634 for details. */
1788 gimple_seq old_eh_seq = eh_seq;
1789 eh_seq = NULL;
1791 out_label = NULL;
1792 cleanup = gimple_try_cleanup (tp);
1793 for (gsi = gsi_start (cleanup);
1794 !gsi_end_p (gsi);
1795 gsi_next (&gsi))
1797 eh_catch c;
1798 gcatch *catch_stmt;
1799 gimple_seq handler;
1801 catch_stmt = as_a <gcatch *> (gsi_stmt (gsi));
1802 c = gen_eh_region_catch (try_region, gimple_catch_types (catch_stmt));
1804 handler = gimple_catch_handler (catch_stmt);
1805 lower_eh_constructs_1 (&this_state, &handler);
1807 c->label = create_artificial_label (UNKNOWN_LOCATION);
1808 x = gimple_build_label (c->label);
1809 gimple_seq_add_stmt (&new_seq, x);
1811 gimple_seq_add_seq (&new_seq, handler);
1813 if (gimple_seq_may_fallthru (new_seq))
1815 if (!out_label)
1816 out_label = create_artificial_label (try_catch_loc);
1818 x = gimple_build_goto (out_label);
1819 gimple_seq_add_stmt (&new_seq, x);
1821 if (!c->type_list)
1822 break;
1825 gimple_try_set_cleanup (tp, new_seq);
1827 gimple_seq new_eh_seq = eh_seq;
1828 eh_seq = old_eh_seq;
1829 gimple_seq ret_seq = frob_into_branch_around (tp, try_region, out_label);
1830 gimple_seq_add_seq (&eh_seq, new_eh_seq);
1831 return ret_seq;
1834 /* A subroutine of lower_eh_constructs_1. Lower a GIMPLE_TRY with a
1835 GIMPLE_EH_FILTER to a sequence of labels and blocks, plus the exception
1836 region trees that record all the magic. */
1838 static gimple_seq
1839 lower_eh_filter (struct leh_state *state, gtry *tp)
1841 struct leh_state this_state = *state;
1842 eh_region this_region = NULL;
1843 gimple *inner, *x;
1844 gimple_seq new_seq;
1846 inner = gimple_seq_first_stmt (gimple_try_cleanup (tp));
1848 if (flag_exceptions)
1850 this_region = gen_eh_region_allowed (state->cur_region,
1851 gimple_eh_filter_types (inner));
1852 this_state.cur_region = this_region;
1855 lower_eh_constructs_1 (&this_state, gimple_try_eval_ptr (tp));
1857 if (!eh_region_may_contain_throw (this_region))
1858 return gimple_try_eval (tp);
1860 new_seq = NULL;
1861 this_state.cur_region = state->cur_region;
1862 this_state.ehp_region = this_region;
1864 emit_eh_dispatch (&new_seq, this_region);
1865 emit_resx (&new_seq, this_region);
1867 this_region->u.allowed.label = create_artificial_label (UNKNOWN_LOCATION);
1868 x = gimple_build_label (this_region->u.allowed.label);
1869 gimple_seq_add_stmt (&new_seq, x);
1871 lower_eh_constructs_1 (&this_state, gimple_eh_filter_failure_ptr (inner));
1872 gimple_seq_add_seq (&new_seq, gimple_eh_filter_failure (inner));
1874 gimple_try_set_cleanup (tp, new_seq);
1876 return frob_into_branch_around (tp, this_region, NULL);
1879 /* A subroutine of lower_eh_constructs_1. Lower a GIMPLE_TRY with
1880 an GIMPLE_EH_MUST_NOT_THROW to a sequence of labels and blocks,
1881 plus the exception region trees that record all the magic. */
1883 static gimple_seq
1884 lower_eh_must_not_throw (struct leh_state *state, gtry *tp)
1886 struct leh_state this_state = *state;
1888 if (flag_exceptions)
1890 gimple *inner = gimple_seq_first_stmt (gimple_try_cleanup (tp));
1891 eh_region this_region;
1893 this_region = gen_eh_region_must_not_throw (state->cur_region);
1894 this_region->u.must_not_throw.failure_decl
1895 = gimple_eh_must_not_throw_fndecl (
1896 as_a <geh_mnt *> (inner));
1897 this_region->u.must_not_throw.failure_loc
1898 = LOCATION_LOCUS (gimple_location (tp));
1900 /* In order to get mangling applied to this decl, we must mark it
1901 used now. Otherwise, pass_ipa_free_lang_data won't think it
1902 needs to happen. */
1903 TREE_USED (this_region->u.must_not_throw.failure_decl) = 1;
1905 this_state.cur_region = this_region;
1908 lower_eh_constructs_1 (&this_state, gimple_try_eval_ptr (tp));
1910 return gimple_try_eval (tp);
1913 /* Implement a cleanup expression. This is similar to try-finally,
1914 except that we only execute the cleanup block for exception edges. */
1916 static gimple_seq
1917 lower_cleanup (struct leh_state *state, gtry *tp)
1919 struct leh_state this_state = *state;
1920 eh_region this_region = NULL;
1921 struct leh_tf_state fake_tf;
1922 gimple_seq result;
1923 bool cleanup_dead = cleanup_is_dead_in (state->cur_region);
1925 if (flag_exceptions && !cleanup_dead)
1927 this_region = gen_eh_region_cleanup (state->cur_region);
1928 this_state.cur_region = this_region;
1931 lower_eh_constructs_1 (&this_state, gimple_try_eval_ptr (tp));
1933 if (cleanup_dead || !eh_region_may_contain_throw (this_region))
1934 return gimple_try_eval (tp);
1936 /* Build enough of a try-finally state so that we can reuse
1937 honor_protect_cleanup_actions. */
1938 memset (&fake_tf, 0, sizeof (fake_tf));
1939 fake_tf.top_p = fake_tf.try_finally_expr = tp;
1940 fake_tf.outer = state;
1941 fake_tf.region = this_region;
1942 fake_tf.may_fallthru = gimple_seq_may_fallthru (gimple_try_eval (tp));
1943 fake_tf.may_throw = true;
1945 honor_protect_cleanup_actions (state, NULL, &fake_tf);
1947 if (fake_tf.may_throw)
1949 /* In this case honor_protect_cleanup_actions had nothing to do,
1950 and we should process this normally. */
1951 lower_eh_constructs_1 (state, gimple_try_cleanup_ptr (tp));
1952 result = frob_into_branch_around (tp, this_region,
1953 fake_tf.fallthru_label);
1955 else
1957 /* In this case honor_protect_cleanup_actions did nearly all of
1958 the work. All we have left is to append the fallthru_label. */
1960 result = gimple_try_eval (tp);
1961 if (fake_tf.fallthru_label)
1963 gimple *x = gimple_build_label (fake_tf.fallthru_label);
1964 gimple_seq_add_stmt (&result, x);
1967 return result;
1970 /* Main loop for lowering eh constructs. Also moves gsi to the next
1971 statement. */
1973 static void
1974 lower_eh_constructs_2 (struct leh_state *state, gimple_stmt_iterator *gsi)
1976 gimple_seq replace;
1977 gimple *x;
1978 gimple *stmt = gsi_stmt (*gsi);
1980 switch (gimple_code (stmt))
1982 case GIMPLE_CALL:
1984 tree fndecl = gimple_call_fndecl (stmt);
1985 tree rhs, lhs;
1987 if (fndecl && DECL_BUILT_IN_CLASS (fndecl) == BUILT_IN_NORMAL)
1988 switch (DECL_FUNCTION_CODE (fndecl))
1990 case BUILT_IN_EH_POINTER:
1991 /* The front end may have generated a call to
1992 __builtin_eh_pointer (0) within a catch region. Replace
1993 this zero argument with the current catch region number. */
1994 if (state->ehp_region)
1996 tree nr = build_int_cst (integer_type_node,
1997 state->ehp_region->index);
1998 gimple_call_set_arg (stmt, 0, nr);
2000 else
2002 /* The user has dome something silly. Remove it. */
2003 rhs = null_pointer_node;
2004 goto do_replace;
2006 break;
2008 case BUILT_IN_EH_FILTER:
2009 /* ??? This should never appear, but since it's a builtin it
2010 is accessible to abuse by users. Just remove it and
2011 replace the use with the arbitrary value zero. */
2012 rhs = build_int_cst (TREE_TYPE (TREE_TYPE (fndecl)), 0);
2013 do_replace:
2014 lhs = gimple_call_lhs (stmt);
2015 x = gimple_build_assign (lhs, rhs);
2016 gsi_insert_before (gsi, x, GSI_SAME_STMT);
2017 /* FALLTHRU */
2019 case BUILT_IN_EH_COPY_VALUES:
2020 /* Likewise this should not appear. Remove it. */
2021 gsi_remove (gsi, true);
2022 return;
2024 default:
2025 break;
2028 /* FALLTHRU */
2030 case GIMPLE_ASSIGN:
2031 /* If the stmt can throw use a new temporary for the assignment
2032 to a LHS. This makes sure the old value of the LHS is
2033 available on the EH edge. Only do so for statements that
2034 potentially fall through (no noreturn calls e.g.), otherwise
2035 this new assignment might create fake fallthru regions. */
2036 if (stmt_could_throw_p (stmt)
2037 && gimple_has_lhs (stmt)
2038 && gimple_stmt_may_fallthru (stmt)
2039 && !tree_could_throw_p (gimple_get_lhs (stmt))
2040 && is_gimple_reg_type (TREE_TYPE (gimple_get_lhs (stmt))))
2042 tree lhs = gimple_get_lhs (stmt);
2043 tree tmp = create_tmp_var (TREE_TYPE (lhs));
2044 gimple *s = gimple_build_assign (lhs, tmp);
2045 gimple_set_location (s, gimple_location (stmt));
2046 gimple_set_block (s, gimple_block (stmt));
2047 gimple_set_lhs (stmt, tmp);
2048 if (TREE_CODE (TREE_TYPE (tmp)) == COMPLEX_TYPE
2049 || TREE_CODE (TREE_TYPE (tmp)) == VECTOR_TYPE)
2050 DECL_GIMPLE_REG_P (tmp) = 1;
2051 gsi_insert_after (gsi, s, GSI_SAME_STMT);
2053 /* Look for things that can throw exceptions, and record them. */
2054 if (state->cur_region && stmt_could_throw_p (stmt))
2056 record_stmt_eh_region (state->cur_region, stmt);
2057 note_eh_region_may_contain_throw (state->cur_region);
2059 break;
2061 case GIMPLE_COND:
2062 case GIMPLE_GOTO:
2063 case GIMPLE_RETURN:
2064 maybe_record_in_goto_queue (state, stmt);
2065 break;
2067 case GIMPLE_SWITCH:
2068 verify_norecord_switch_expr (state, as_a <gswitch *> (stmt));
2069 break;
2071 case GIMPLE_TRY:
2073 gtry *try_stmt = as_a <gtry *> (stmt);
2074 if (gimple_try_kind (try_stmt) == GIMPLE_TRY_FINALLY)
2075 replace = lower_try_finally (state, try_stmt);
2076 else
2078 x = gimple_seq_first_stmt (gimple_try_cleanup (try_stmt));
2079 if (!x)
2081 replace = gimple_try_eval (try_stmt);
2082 lower_eh_constructs_1 (state, &replace);
2084 else
2085 switch (gimple_code (x))
2087 case GIMPLE_CATCH:
2088 replace = lower_catch (state, try_stmt);
2089 break;
2090 case GIMPLE_EH_FILTER:
2091 replace = lower_eh_filter (state, try_stmt);
2092 break;
2093 case GIMPLE_EH_MUST_NOT_THROW:
2094 replace = lower_eh_must_not_throw (state, try_stmt);
2095 break;
2096 case GIMPLE_EH_ELSE:
2097 /* This code is only valid with GIMPLE_TRY_FINALLY. */
2098 gcc_unreachable ();
2099 default:
2100 replace = lower_cleanup (state, try_stmt);
2101 break;
2106 /* Remove the old stmt and insert the transformed sequence
2107 instead. */
2108 gsi_insert_seq_before (gsi, replace, GSI_SAME_STMT);
2109 gsi_remove (gsi, true);
2111 /* Return since we don't want gsi_next () */
2112 return;
2114 case GIMPLE_EH_ELSE:
2115 /* We should be eliminating this in lower_try_finally et al. */
2116 gcc_unreachable ();
2118 default:
2119 /* A type, a decl, or some kind of statement that we're not
2120 interested in. Don't walk them. */
2121 break;
2124 gsi_next (gsi);
2127 /* A helper to unwrap a gimple_seq and feed stmts to lower_eh_constructs_2. */
2129 static void
2130 lower_eh_constructs_1 (struct leh_state *state, gimple_seq *pseq)
2132 gimple_stmt_iterator gsi;
2133 for (gsi = gsi_start (*pseq); !gsi_end_p (gsi);)
2134 lower_eh_constructs_2 (state, &gsi);
2137 namespace {
2139 const pass_data pass_data_lower_eh =
2141 GIMPLE_PASS, /* type */
2142 "eh", /* name */
2143 OPTGROUP_NONE, /* optinfo_flags */
2144 TV_TREE_EH, /* tv_id */
2145 PROP_gimple_lcf, /* properties_required */
2146 PROP_gimple_leh, /* properties_provided */
2147 0, /* properties_destroyed */
2148 0, /* todo_flags_start */
2149 0, /* todo_flags_finish */
2152 class pass_lower_eh : public gimple_opt_pass
2154 public:
2155 pass_lower_eh (gcc::context *ctxt)
2156 : gimple_opt_pass (pass_data_lower_eh, ctxt)
2159 /* opt_pass methods: */
2160 virtual unsigned int execute (function *);
2162 }; // class pass_lower_eh
2164 unsigned int
2165 pass_lower_eh::execute (function *fun)
2167 struct leh_state null_state;
2168 gimple_seq bodyp;
2170 bodyp = gimple_body (current_function_decl);
2171 if (bodyp == NULL)
2172 return 0;
2174 finally_tree = new hash_table<finally_tree_hasher> (31);
2175 eh_region_may_contain_throw_map = BITMAP_ALLOC (NULL);
2176 memset (&null_state, 0, sizeof (null_state));
2178 collect_finally_tree_1 (bodyp, NULL);
2179 lower_eh_constructs_1 (&null_state, &bodyp);
2180 gimple_set_body (current_function_decl, bodyp);
2182 /* We assume there's a return statement, or something, at the end of
2183 the function, and thus ploping the EH sequence afterward won't
2184 change anything. */
2185 gcc_assert (!gimple_seq_may_fallthru (bodyp));
2186 gimple_seq_add_seq (&bodyp, eh_seq);
2188 /* We assume that since BODYP already existed, adding EH_SEQ to it
2189 didn't change its value, and we don't have to re-set the function. */
2190 gcc_assert (bodyp == gimple_body (current_function_decl));
2192 delete finally_tree;
2193 finally_tree = NULL;
2194 BITMAP_FREE (eh_region_may_contain_throw_map);
2195 eh_seq = NULL;
2197 /* If this function needs a language specific EH personality routine
2198 and the frontend didn't already set one do so now. */
2199 if (function_needs_eh_personality (fun) == eh_personality_lang
2200 && !DECL_FUNCTION_PERSONALITY (current_function_decl))
2201 DECL_FUNCTION_PERSONALITY (current_function_decl)
2202 = lang_hooks.eh_personality ();
2204 return 0;
2207 } // anon namespace
2209 gimple_opt_pass *
2210 make_pass_lower_eh (gcc::context *ctxt)
2212 return new pass_lower_eh (ctxt);
2215 /* Create the multiple edges from an EH_DISPATCH statement to all of
2216 the possible handlers for its EH region. Return true if there's
2217 no fallthru edge; false if there is. */
2219 bool
2220 make_eh_dispatch_edges (geh_dispatch *stmt)
2222 eh_region r;
2223 eh_catch c;
2224 basic_block src, dst;
2226 r = get_eh_region_from_number (gimple_eh_dispatch_region (stmt));
2227 src = gimple_bb (stmt);
2229 switch (r->type)
2231 case ERT_TRY:
2232 for (c = r->u.eh_try.first_catch; c ; c = c->next_catch)
2234 dst = label_to_block (c->label);
2235 make_edge (src, dst, 0);
2237 /* A catch-all handler doesn't have a fallthru. */
2238 if (c->type_list == NULL)
2239 return false;
2241 break;
2243 case ERT_ALLOWED_EXCEPTIONS:
2244 dst = label_to_block (r->u.allowed.label);
2245 make_edge (src, dst, 0);
2246 break;
2248 default:
2249 gcc_unreachable ();
2252 return true;
2255 /* Create the single EH edge from STMT to its nearest landing pad,
2256 if there is such a landing pad within the current function. */
2258 void
2259 make_eh_edges (gimple *stmt)
2261 basic_block src, dst;
2262 eh_landing_pad lp;
2263 int lp_nr;
2265 lp_nr = lookup_stmt_eh_lp (stmt);
2266 if (lp_nr <= 0)
2267 return;
2269 lp = get_eh_landing_pad_from_number (lp_nr);
2270 gcc_assert (lp != NULL);
2272 src = gimple_bb (stmt);
2273 dst = label_to_block (lp->post_landing_pad);
2274 make_edge (src, dst, EDGE_EH);
2277 /* Do the work in redirecting EDGE_IN to NEW_BB within the EH region tree;
2278 do not actually perform the final edge redirection.
2280 CHANGE_REGION is true when we're being called from cleanup_empty_eh and
2281 we intend to change the destination EH region as well; this means
2282 EH_LANDING_PAD_NR must already be set on the destination block label.
2283 If false, we're being called from generic cfg manipulation code and we
2284 should preserve our place within the region tree. */
2286 static void
2287 redirect_eh_edge_1 (edge edge_in, basic_block new_bb, bool change_region)
2289 eh_landing_pad old_lp, new_lp;
2290 basic_block old_bb;
2291 gimple *throw_stmt;
2292 int old_lp_nr, new_lp_nr;
2293 tree old_label, new_label;
2294 edge_iterator ei;
2295 edge e;
2297 old_bb = edge_in->dest;
2298 old_label = gimple_block_label (old_bb);
2299 old_lp_nr = EH_LANDING_PAD_NR (old_label);
2300 gcc_assert (old_lp_nr > 0);
2301 old_lp = get_eh_landing_pad_from_number (old_lp_nr);
2303 throw_stmt = last_stmt (edge_in->src);
2304 gcc_assert (lookup_stmt_eh_lp (throw_stmt) == old_lp_nr);
2306 new_label = gimple_block_label (new_bb);
2308 /* Look for an existing region that might be using NEW_BB already. */
2309 new_lp_nr = EH_LANDING_PAD_NR (new_label);
2310 if (new_lp_nr)
2312 new_lp = get_eh_landing_pad_from_number (new_lp_nr);
2313 gcc_assert (new_lp);
2315 /* Unless CHANGE_REGION is true, the new and old landing pad
2316 had better be associated with the same EH region. */
2317 gcc_assert (change_region || new_lp->region == old_lp->region);
2319 else
2321 new_lp = NULL;
2322 gcc_assert (!change_region);
2325 /* Notice when we redirect the last EH edge away from OLD_BB. */
2326 FOR_EACH_EDGE (e, ei, old_bb->preds)
2327 if (e != edge_in && (e->flags & EDGE_EH))
2328 break;
2330 if (new_lp)
2332 /* NEW_LP already exists. If there are still edges into OLD_LP,
2333 there's nothing to do with the EH tree. If there are no more
2334 edges into OLD_LP, then we want to remove OLD_LP as it is unused.
2335 If CHANGE_REGION is true, then our caller is expecting to remove
2336 the landing pad. */
2337 if (e == NULL && !change_region)
2338 remove_eh_landing_pad (old_lp);
2340 else
2342 /* No correct landing pad exists. If there are no more edges
2343 into OLD_LP, then we can simply re-use the existing landing pad.
2344 Otherwise, we have to create a new landing pad. */
2345 if (e == NULL)
2347 EH_LANDING_PAD_NR (old_lp->post_landing_pad) = 0;
2348 new_lp = old_lp;
2350 else
2351 new_lp = gen_eh_landing_pad (old_lp->region);
2352 new_lp->post_landing_pad = new_label;
2353 EH_LANDING_PAD_NR (new_label) = new_lp->index;
2356 /* Maybe move the throwing statement to the new region. */
2357 if (old_lp != new_lp)
2359 remove_stmt_from_eh_lp (throw_stmt);
2360 add_stmt_to_eh_lp (throw_stmt, new_lp->index);
2364 /* Redirect EH edge E to NEW_BB. */
2366 edge
2367 redirect_eh_edge (edge edge_in, basic_block new_bb)
2369 redirect_eh_edge_1 (edge_in, new_bb, false);
2370 return ssa_redirect_edge (edge_in, new_bb);
2373 /* This is a subroutine of gimple_redirect_edge_and_branch. Update the
2374 labels for redirecting a non-fallthru EH_DISPATCH edge E to NEW_BB.
2375 The actual edge update will happen in the caller. */
2377 void
2378 redirect_eh_dispatch_edge (geh_dispatch *stmt, edge e, basic_block new_bb)
2380 tree new_lab = gimple_block_label (new_bb);
2381 bool any_changed = false;
2382 basic_block old_bb;
2383 eh_region r;
2384 eh_catch c;
2386 r = get_eh_region_from_number (gimple_eh_dispatch_region (stmt));
2387 switch (r->type)
2389 case ERT_TRY:
2390 for (c = r->u.eh_try.first_catch; c ; c = c->next_catch)
2392 old_bb = label_to_block (c->label);
2393 if (old_bb == e->dest)
2395 c->label = new_lab;
2396 any_changed = true;
2399 break;
2401 case ERT_ALLOWED_EXCEPTIONS:
2402 old_bb = label_to_block (r->u.allowed.label);
2403 gcc_assert (old_bb == e->dest);
2404 r->u.allowed.label = new_lab;
2405 any_changed = true;
2406 break;
2408 default:
2409 gcc_unreachable ();
2412 gcc_assert (any_changed);
2415 /* Helper function for operation_could_trap_p and stmt_could_throw_p. */
2417 bool
2418 operation_could_trap_helper_p (enum tree_code op,
2419 bool fp_operation,
2420 bool honor_trapv,
2421 bool honor_nans,
2422 bool honor_snans,
2423 tree divisor,
2424 bool *handled)
2426 *handled = true;
2427 switch (op)
2429 case TRUNC_DIV_EXPR:
2430 case CEIL_DIV_EXPR:
2431 case FLOOR_DIV_EXPR:
2432 case ROUND_DIV_EXPR:
2433 case EXACT_DIV_EXPR:
2434 case CEIL_MOD_EXPR:
2435 case FLOOR_MOD_EXPR:
2436 case ROUND_MOD_EXPR:
2437 case TRUNC_MOD_EXPR:
2438 case RDIV_EXPR:
2439 if (honor_snans)
2440 return true;
2441 if (fp_operation)
2442 return flag_trapping_math;
2443 if (!TREE_CONSTANT (divisor) || integer_zerop (divisor))
2444 return true;
2445 return false;
2447 case LT_EXPR:
2448 case LE_EXPR:
2449 case GT_EXPR:
2450 case GE_EXPR:
2451 case LTGT_EXPR:
2452 /* Some floating point comparisons may trap. */
2453 return honor_nans;
2455 case EQ_EXPR:
2456 case NE_EXPR:
2457 case UNORDERED_EXPR:
2458 case ORDERED_EXPR:
2459 case UNLT_EXPR:
2460 case UNLE_EXPR:
2461 case UNGT_EXPR:
2462 case UNGE_EXPR:
2463 case UNEQ_EXPR:
2464 return honor_snans;
2466 case NEGATE_EXPR:
2467 case ABS_EXPR:
2468 case CONJ_EXPR:
2469 /* These operations don't trap with floating point. */
2470 if (honor_trapv)
2471 return true;
2472 return false;
2474 case PLUS_EXPR:
2475 case MINUS_EXPR:
2476 case MULT_EXPR:
2477 /* Any floating arithmetic may trap. */
2478 if (fp_operation && flag_trapping_math)
2479 return true;
2480 if (honor_trapv)
2481 return true;
2482 return false;
2484 case COMPLEX_EXPR:
2485 case CONSTRUCTOR:
2486 /* Constructing an object cannot trap. */
2487 return false;
2489 default:
2490 /* Any floating arithmetic may trap. */
2491 if (fp_operation && flag_trapping_math)
2492 return true;
2494 *handled = false;
2495 return false;
2499 /* Return true if operation OP may trap. FP_OPERATION is true if OP is applied
2500 on floating-point values. HONOR_TRAPV is true if OP is applied on integer
2501 type operands that may trap. If OP is a division operator, DIVISOR contains
2502 the value of the divisor. */
2504 bool
2505 operation_could_trap_p (enum tree_code op, bool fp_operation, bool honor_trapv,
2506 tree divisor)
2508 bool honor_nans = (fp_operation && flag_trapping_math
2509 && !flag_finite_math_only);
2510 bool honor_snans = fp_operation && flag_signaling_nans != 0;
2511 bool handled;
2513 if (TREE_CODE_CLASS (op) != tcc_comparison
2514 && TREE_CODE_CLASS (op) != tcc_unary
2515 && TREE_CODE_CLASS (op) != tcc_binary
2516 && op != FMA_EXPR)
2517 return false;
2519 return operation_could_trap_helper_p (op, fp_operation, honor_trapv,
2520 honor_nans, honor_snans, divisor,
2521 &handled);
2525 /* Returns true if it is possible to prove that the index of
2526 an array access REF (an ARRAY_REF expression) falls into the
2527 array bounds. */
2529 static bool
2530 in_array_bounds_p (tree ref)
2532 tree idx = TREE_OPERAND (ref, 1);
2533 tree min, max;
2535 if (TREE_CODE (idx) != INTEGER_CST)
2536 return false;
2538 min = array_ref_low_bound (ref);
2539 max = array_ref_up_bound (ref);
2540 if (!min
2541 || !max
2542 || TREE_CODE (min) != INTEGER_CST
2543 || TREE_CODE (max) != INTEGER_CST)
2544 return false;
2546 if (tree_int_cst_lt (idx, min)
2547 || tree_int_cst_lt (max, idx))
2548 return false;
2550 return true;
2553 /* Returns true if it is possible to prove that the range of
2554 an array access REF (an ARRAY_RANGE_REF expression) falls
2555 into the array bounds. */
2557 static bool
2558 range_in_array_bounds_p (tree ref)
2560 tree domain_type = TYPE_DOMAIN (TREE_TYPE (ref));
2561 tree range_min, range_max, min, max;
2563 range_min = TYPE_MIN_VALUE (domain_type);
2564 range_max = TYPE_MAX_VALUE (domain_type);
2565 if (!range_min
2566 || !range_max
2567 || TREE_CODE (range_min) != INTEGER_CST
2568 || TREE_CODE (range_max) != INTEGER_CST)
2569 return false;
2571 min = array_ref_low_bound (ref);
2572 max = array_ref_up_bound (ref);
2573 if (!min
2574 || !max
2575 || TREE_CODE (min) != INTEGER_CST
2576 || TREE_CODE (max) != INTEGER_CST)
2577 return false;
2579 if (tree_int_cst_lt (range_min, min)
2580 || tree_int_cst_lt (max, range_max))
2581 return false;
2583 return true;
2586 /* Return true if EXPR can trap, as in dereferencing an invalid pointer
2587 location or floating point arithmetic. C.f. the rtl version, may_trap_p.
2588 This routine expects only GIMPLE lhs or rhs input. */
2590 bool
2591 tree_could_trap_p (tree expr)
2593 enum tree_code code;
2594 bool fp_operation = false;
2595 bool honor_trapv = false;
2596 tree t, base, div = NULL_TREE;
2598 if (!expr)
2599 return false;
2601 code = TREE_CODE (expr);
2602 t = TREE_TYPE (expr);
2604 if (t)
2606 if (COMPARISON_CLASS_P (expr))
2607 fp_operation = FLOAT_TYPE_P (TREE_TYPE (TREE_OPERAND (expr, 0)));
2608 else
2609 fp_operation = FLOAT_TYPE_P (t);
2610 honor_trapv = INTEGRAL_TYPE_P (t) && TYPE_OVERFLOW_TRAPS (t);
2613 if (TREE_CODE_CLASS (code) == tcc_binary)
2614 div = TREE_OPERAND (expr, 1);
2615 if (operation_could_trap_p (code, fp_operation, honor_trapv, div))
2616 return true;
2618 restart:
2619 switch (code)
2621 case COMPONENT_REF:
2622 case REALPART_EXPR:
2623 case IMAGPART_EXPR:
2624 case BIT_FIELD_REF:
2625 case VIEW_CONVERT_EXPR:
2626 case WITH_SIZE_EXPR:
2627 expr = TREE_OPERAND (expr, 0);
2628 code = TREE_CODE (expr);
2629 goto restart;
2631 case ARRAY_RANGE_REF:
2632 base = TREE_OPERAND (expr, 0);
2633 if (tree_could_trap_p (base))
2634 return true;
2635 if (TREE_THIS_NOTRAP (expr))
2636 return false;
2637 return !range_in_array_bounds_p (expr);
2639 case ARRAY_REF:
2640 base = TREE_OPERAND (expr, 0);
2641 if (tree_could_trap_p (base))
2642 return true;
2643 if (TREE_THIS_NOTRAP (expr))
2644 return false;
2645 return !in_array_bounds_p (expr);
2647 case TARGET_MEM_REF:
2648 case MEM_REF:
2649 if (TREE_CODE (TREE_OPERAND (expr, 0)) == ADDR_EXPR
2650 && tree_could_trap_p (TREE_OPERAND (TREE_OPERAND (expr, 0), 0)))
2651 return true;
2652 if (TREE_THIS_NOTRAP (expr))
2653 return false;
2654 /* We cannot prove that the access is in-bounds when we have
2655 variable-index TARGET_MEM_REFs. */
2656 if (code == TARGET_MEM_REF
2657 && (TMR_INDEX (expr) || TMR_INDEX2 (expr)))
2658 return true;
2659 if (TREE_CODE (TREE_OPERAND (expr, 0)) == ADDR_EXPR)
2661 tree base = TREE_OPERAND (TREE_OPERAND (expr, 0), 0);
2662 poly_offset_int off = mem_ref_offset (expr);
2663 if (maybe_lt (off, 0))
2664 return true;
2665 if (TREE_CODE (base) == STRING_CST)
2666 return maybe_le (TREE_STRING_LENGTH (base), off);
2667 tree size = DECL_SIZE_UNIT (base);
2668 if (size == NULL_TREE
2669 || !poly_int_tree_p (size)
2670 || maybe_le (wi::to_poly_offset (size), off))
2671 return true;
2672 /* Now we are sure the first byte of the access is inside
2673 the object. */
2674 return false;
2676 return true;
2678 case INDIRECT_REF:
2679 return !TREE_THIS_NOTRAP (expr);
2681 case ASM_EXPR:
2682 return TREE_THIS_VOLATILE (expr);
2684 case CALL_EXPR:
2685 t = get_callee_fndecl (expr);
2686 /* Assume that calls to weak functions may trap. */
2687 if (!t || !DECL_P (t))
2688 return true;
2689 if (DECL_WEAK (t))
2690 return tree_could_trap_p (t);
2691 return false;
2693 case FUNCTION_DECL:
2694 /* Assume that accesses to weak functions may trap, unless we know
2695 they are certainly defined in current TU or in some other
2696 LTO partition. */
2697 if (DECL_WEAK (expr) && !DECL_COMDAT (expr) && DECL_EXTERNAL (expr))
2699 cgraph_node *node = cgraph_node::get (expr);
2700 if (node)
2701 node = node->function_symbol ();
2702 return !(node && node->in_other_partition);
2704 return false;
2706 case VAR_DECL:
2707 /* Assume that accesses to weak vars may trap, unless we know
2708 they are certainly defined in current TU or in some other
2709 LTO partition. */
2710 if (DECL_WEAK (expr) && !DECL_COMDAT (expr) && DECL_EXTERNAL (expr))
2712 varpool_node *node = varpool_node::get (expr);
2713 if (node)
2714 node = node->ultimate_alias_target ();
2715 return !(node && node->in_other_partition);
2717 return false;
2719 default:
2720 return false;
2724 /* Return non-NULL if there is an integer operation with trapping overflow
2725 we can rewrite into non-trapping. Called via walk_tree from
2726 rewrite_to_non_trapping_overflow. */
2728 static tree
2729 find_trapping_overflow (tree *tp, int *walk_subtrees, void *data)
2731 if (EXPR_P (*tp)
2732 && ANY_INTEGRAL_TYPE_P (TREE_TYPE (*tp))
2733 && !operation_no_trapping_overflow (TREE_TYPE (*tp), TREE_CODE (*tp)))
2734 return *tp;
2735 if (IS_TYPE_OR_DECL_P (*tp)
2736 || (TREE_CODE (*tp) == SAVE_EXPR && data == NULL))
2737 *walk_subtrees = 0;
2738 return NULL_TREE;
2741 /* Rewrite selected operations into unsigned arithmetics, so that they
2742 don't trap on overflow. */
2744 static tree
2745 replace_trapping_overflow (tree *tp, int *walk_subtrees, void *data)
2747 if (find_trapping_overflow (tp, walk_subtrees, data))
2749 tree type = TREE_TYPE (*tp);
2750 tree utype = unsigned_type_for (type);
2751 *walk_subtrees = 0;
2752 int len = TREE_OPERAND_LENGTH (*tp);
2753 for (int i = 0; i < len; ++i)
2754 walk_tree (&TREE_OPERAND (*tp, i), replace_trapping_overflow,
2755 data, (hash_set<tree> *) data);
2757 if (TREE_CODE (*tp) == ABS_EXPR)
2759 tree op = TREE_OPERAND (*tp, 0);
2760 op = save_expr (op);
2761 /* save_expr skips simple arithmetics, which is undesirable
2762 here, if it might trap due to flag_trapv. We need to
2763 force a SAVE_EXPR in the COND_EXPR condition, to evaluate
2764 it before the comparison. */
2765 if (EXPR_P (op)
2766 && TREE_CODE (op) != SAVE_EXPR
2767 && walk_tree (&op, find_trapping_overflow, NULL, NULL))
2769 op = build1_loc (EXPR_LOCATION (op), SAVE_EXPR, type, op);
2770 TREE_SIDE_EFFECTS (op) = 1;
2772 /* Change abs (op) to op < 0 ? -op : op and handle the NEGATE_EXPR
2773 like other signed integer trapping operations. */
2774 tree cond = fold_build2 (LT_EXPR, boolean_type_node,
2775 op, build_int_cst (type, 0));
2776 tree neg = fold_build1 (NEGATE_EXPR, utype,
2777 fold_convert (utype, op));
2778 *tp = fold_build3 (COND_EXPR, type, cond,
2779 fold_convert (type, neg), op);
2781 else
2783 TREE_TYPE (*tp) = utype;
2784 len = TREE_OPERAND_LENGTH (*tp);
2785 for (int i = 0; i < len; ++i)
2786 TREE_OPERAND (*tp, i)
2787 = fold_convert (utype, TREE_OPERAND (*tp, i));
2788 *tp = fold_convert (type, *tp);
2791 return NULL_TREE;
2794 /* If any subexpression of EXPR can trap due to -ftrapv, rewrite it
2795 using unsigned arithmetics to avoid traps in it. */
2797 tree
2798 rewrite_to_non_trapping_overflow (tree expr)
2800 if (!flag_trapv)
2801 return expr;
2802 hash_set<tree> pset;
2803 if (!walk_tree (&expr, find_trapping_overflow, &pset, &pset))
2804 return expr;
2805 expr = unshare_expr (expr);
2806 pset.empty ();
2807 walk_tree (&expr, replace_trapping_overflow, &pset, &pset);
2808 return expr;
2811 /* Helper for stmt_could_throw_p. Return true if STMT (assumed to be a
2812 an assignment or a conditional) may throw. */
2814 static bool
2815 stmt_could_throw_1_p (gassign *stmt)
2817 enum tree_code code = gimple_assign_rhs_code (stmt);
2818 bool honor_nans = false;
2819 bool honor_snans = false;
2820 bool fp_operation = false;
2821 bool honor_trapv = false;
2822 tree t;
2823 size_t i;
2824 bool handled, ret;
2826 if (TREE_CODE_CLASS (code) == tcc_comparison
2827 || TREE_CODE_CLASS (code) == tcc_unary
2828 || TREE_CODE_CLASS (code) == tcc_binary
2829 || code == FMA_EXPR)
2831 if (TREE_CODE_CLASS (code) == tcc_comparison)
2832 t = TREE_TYPE (gimple_assign_rhs1 (stmt));
2833 else
2834 t = gimple_expr_type (stmt);
2835 fp_operation = FLOAT_TYPE_P (t);
2836 if (fp_operation)
2838 honor_nans = flag_trapping_math && !flag_finite_math_only;
2839 honor_snans = flag_signaling_nans != 0;
2841 else if (INTEGRAL_TYPE_P (t) && TYPE_OVERFLOW_TRAPS (t))
2842 honor_trapv = true;
2845 /* First check the LHS. */
2846 if (tree_could_trap_p (gimple_assign_lhs (stmt)))
2847 return true;
2849 /* Check if the main expression may trap. */
2850 ret = operation_could_trap_helper_p (code, fp_operation, honor_trapv,
2851 honor_nans, honor_snans,
2852 gimple_assign_rhs2 (stmt),
2853 &handled);
2854 if (handled)
2855 return ret;
2857 /* If the expression does not trap, see if any of the individual operands may
2858 trap. */
2859 for (i = 1; i < gimple_num_ops (stmt); i++)
2860 if (tree_could_trap_p (gimple_op (stmt, i)))
2861 return true;
2863 return false;
2867 /* Return true if statement STMT could throw an exception. */
2869 bool
2870 stmt_could_throw_p (gimple *stmt)
2872 if (!flag_exceptions)
2873 return false;
2875 /* The only statements that can throw an exception are assignments,
2876 conditionals, calls, resx, and asms. */
2877 switch (gimple_code (stmt))
2879 case GIMPLE_RESX:
2880 return true;
2882 case GIMPLE_CALL:
2883 return !gimple_call_nothrow_p (as_a <gcall *> (stmt));
2885 case GIMPLE_COND:
2887 if (!cfun->can_throw_non_call_exceptions)
2888 return false;
2889 gcond *cond = as_a <gcond *> (stmt);
2890 tree lhs = gimple_cond_lhs (cond);
2891 return operation_could_trap_p (gimple_cond_code (cond),
2892 FLOAT_TYPE_P (TREE_TYPE (lhs)),
2893 false, NULL_TREE);
2896 case GIMPLE_ASSIGN:
2897 if (!cfun->can_throw_non_call_exceptions
2898 || gimple_clobber_p (stmt))
2899 return false;
2900 return stmt_could_throw_1_p (as_a <gassign *> (stmt));
2902 case GIMPLE_ASM:
2903 if (!cfun->can_throw_non_call_exceptions)
2904 return false;
2905 return gimple_asm_volatile_p (as_a <gasm *> (stmt));
2907 default:
2908 return false;
2913 /* Return true if expression T could throw an exception. */
2915 bool
2916 tree_could_throw_p (tree t)
2918 if (!flag_exceptions)
2919 return false;
2920 if (TREE_CODE (t) == MODIFY_EXPR)
2922 if (cfun->can_throw_non_call_exceptions
2923 && tree_could_trap_p (TREE_OPERAND (t, 0)))
2924 return true;
2925 t = TREE_OPERAND (t, 1);
2928 if (TREE_CODE (t) == WITH_SIZE_EXPR)
2929 t = TREE_OPERAND (t, 0);
2930 if (TREE_CODE (t) == CALL_EXPR)
2931 return (call_expr_flags (t) & ECF_NOTHROW) == 0;
2932 if (cfun->can_throw_non_call_exceptions)
2933 return tree_could_trap_p (t);
2934 return false;
2937 /* Return true if STMT can throw an exception that is not caught within
2938 the current function (CFUN). */
2940 bool
2941 stmt_can_throw_external (gimple *stmt)
2943 int lp_nr;
2945 if (!stmt_could_throw_p (stmt))
2946 return false;
2948 lp_nr = lookup_stmt_eh_lp (stmt);
2949 return lp_nr == 0;
2952 /* Return true if STMT can throw an exception that is caught within
2953 the current function (CFUN). */
2955 bool
2956 stmt_can_throw_internal (gimple *stmt)
2958 int lp_nr;
2960 if (!stmt_could_throw_p (stmt))
2961 return false;
2963 lp_nr = lookup_stmt_eh_lp (stmt);
2964 return lp_nr > 0;
2967 /* Given a statement STMT in IFUN, if STMT can no longer throw, then
2968 remove any entry it might have from the EH table. Return true if
2969 any change was made. */
2971 bool
2972 maybe_clean_eh_stmt_fn (struct function *ifun, gimple *stmt)
2974 if (stmt_could_throw_p (stmt))
2975 return false;
2976 return remove_stmt_from_eh_lp_fn (ifun, stmt);
2979 /* Likewise, but always use the current function. */
2981 bool
2982 maybe_clean_eh_stmt (gimple *stmt)
2984 return maybe_clean_eh_stmt_fn (cfun, stmt);
2987 /* Given a statement OLD_STMT and a new statement NEW_STMT that has replaced
2988 OLD_STMT in the function, remove OLD_STMT from the EH table and put NEW_STMT
2989 in the table if it should be in there. Return TRUE if a replacement was
2990 done that my require an EH edge purge. */
2992 bool
2993 maybe_clean_or_replace_eh_stmt (gimple *old_stmt, gimple *new_stmt)
2995 int lp_nr = lookup_stmt_eh_lp (old_stmt);
2997 if (lp_nr != 0)
2999 bool new_stmt_could_throw = stmt_could_throw_p (new_stmt);
3001 if (new_stmt == old_stmt && new_stmt_could_throw)
3002 return false;
3004 remove_stmt_from_eh_lp (old_stmt);
3005 if (new_stmt_could_throw)
3007 add_stmt_to_eh_lp (new_stmt, lp_nr);
3008 return false;
3010 else
3011 return true;
3014 return false;
3017 /* Given a statement OLD_STMT in OLD_FUN and a duplicate statement NEW_STMT
3018 in NEW_FUN, copy the EH table data from OLD_STMT to NEW_STMT. The MAP
3019 operand is the return value of duplicate_eh_regions. */
3021 bool
3022 maybe_duplicate_eh_stmt_fn (struct function *new_fun, gimple *new_stmt,
3023 struct function *old_fun, gimple *old_stmt,
3024 hash_map<void *, void *> *map,
3025 int default_lp_nr)
3027 int old_lp_nr, new_lp_nr;
3029 if (!stmt_could_throw_p (new_stmt))
3030 return false;
3032 old_lp_nr = lookup_stmt_eh_lp_fn (old_fun, old_stmt);
3033 if (old_lp_nr == 0)
3035 if (default_lp_nr == 0)
3036 return false;
3037 new_lp_nr = default_lp_nr;
3039 else if (old_lp_nr > 0)
3041 eh_landing_pad old_lp, new_lp;
3043 old_lp = (*old_fun->eh->lp_array)[old_lp_nr];
3044 new_lp = static_cast<eh_landing_pad> (*map->get (old_lp));
3045 new_lp_nr = new_lp->index;
3047 else
3049 eh_region old_r, new_r;
3051 old_r = (*old_fun->eh->region_array)[-old_lp_nr];
3052 new_r = static_cast<eh_region> (*map->get (old_r));
3053 new_lp_nr = -new_r->index;
3056 add_stmt_to_eh_lp_fn (new_fun, new_stmt, new_lp_nr);
3057 return true;
3060 /* Similar, but both OLD_STMT and NEW_STMT are within the current function,
3061 and thus no remapping is required. */
3063 bool
3064 maybe_duplicate_eh_stmt (gimple *new_stmt, gimple *old_stmt)
3066 int lp_nr;
3068 if (!stmt_could_throw_p (new_stmt))
3069 return false;
3071 lp_nr = lookup_stmt_eh_lp (old_stmt);
3072 if (lp_nr == 0)
3073 return false;
3075 add_stmt_to_eh_lp (new_stmt, lp_nr);
3076 return true;
3079 /* Returns TRUE if oneh and twoh are exception handlers (gimple_try_cleanup of
3080 GIMPLE_TRY) that are similar enough to be considered the same. Currently
3081 this only handles handlers consisting of a single call, as that's the
3082 important case for C++: a destructor call for a particular object showing
3083 up in multiple handlers. */
3085 static bool
3086 same_handler_p (gimple_seq oneh, gimple_seq twoh)
3088 gimple_stmt_iterator gsi;
3089 gimple *ones, *twos;
3090 unsigned int ai;
3092 gsi = gsi_start (oneh);
3093 if (!gsi_one_before_end_p (gsi))
3094 return false;
3095 ones = gsi_stmt (gsi);
3097 gsi = gsi_start (twoh);
3098 if (!gsi_one_before_end_p (gsi))
3099 return false;
3100 twos = gsi_stmt (gsi);
3102 if (!is_gimple_call (ones)
3103 || !is_gimple_call (twos)
3104 || gimple_call_lhs (ones)
3105 || gimple_call_lhs (twos)
3106 || gimple_call_chain (ones)
3107 || gimple_call_chain (twos)
3108 || !gimple_call_same_target_p (ones, twos)
3109 || gimple_call_num_args (ones) != gimple_call_num_args (twos))
3110 return false;
3112 for (ai = 0; ai < gimple_call_num_args (ones); ++ai)
3113 if (!operand_equal_p (gimple_call_arg (ones, ai),
3114 gimple_call_arg (twos, ai), 0))
3115 return false;
3117 return true;
3120 /* Optimize
3121 try { A() } finally { try { ~B() } catch { ~A() } }
3122 try { ... } finally { ~A() }
3123 into
3124 try { A() } catch { ~B() }
3125 try { ~B() ... } finally { ~A() }
3127 This occurs frequently in C++, where A is a local variable and B is a
3128 temporary used in the initializer for A. */
3130 static void
3131 optimize_double_finally (gtry *one, gtry *two)
3133 gimple *oneh;
3134 gimple_stmt_iterator gsi;
3135 gimple_seq cleanup;
3137 cleanup = gimple_try_cleanup (one);
3138 gsi = gsi_start (cleanup);
3139 if (!gsi_one_before_end_p (gsi))
3140 return;
3142 oneh = gsi_stmt (gsi);
3143 if (gimple_code (oneh) != GIMPLE_TRY
3144 || gimple_try_kind (oneh) != GIMPLE_TRY_CATCH)
3145 return;
3147 if (same_handler_p (gimple_try_cleanup (oneh), gimple_try_cleanup (two)))
3149 gimple_seq seq = gimple_try_eval (oneh);
3151 gimple_try_set_cleanup (one, seq);
3152 gimple_try_set_kind (one, GIMPLE_TRY_CATCH);
3153 seq = copy_gimple_seq_and_replace_locals (seq);
3154 gimple_seq_add_seq (&seq, gimple_try_eval (two));
3155 gimple_try_set_eval (two, seq);
3159 /* Perform EH refactoring optimizations that are simpler to do when code
3160 flow has been lowered but EH structures haven't. */
3162 static void
3163 refactor_eh_r (gimple_seq seq)
3165 gimple_stmt_iterator gsi;
3166 gimple *one, *two;
3168 one = NULL;
3169 two = NULL;
3170 gsi = gsi_start (seq);
3171 while (1)
3173 one = two;
3174 if (gsi_end_p (gsi))
3175 two = NULL;
3176 else
3177 two = gsi_stmt (gsi);
3178 if (one && two)
3179 if (gtry *try_one = dyn_cast <gtry *> (one))
3180 if (gtry *try_two = dyn_cast <gtry *> (two))
3181 if (gimple_try_kind (try_one) == GIMPLE_TRY_FINALLY
3182 && gimple_try_kind (try_two) == GIMPLE_TRY_FINALLY)
3183 optimize_double_finally (try_one, try_two);
3184 if (one)
3185 switch (gimple_code (one))
3187 case GIMPLE_TRY:
3188 refactor_eh_r (gimple_try_eval (one));
3189 refactor_eh_r (gimple_try_cleanup (one));
3190 break;
3191 case GIMPLE_CATCH:
3192 refactor_eh_r (gimple_catch_handler (as_a <gcatch *> (one)));
3193 break;
3194 case GIMPLE_EH_FILTER:
3195 refactor_eh_r (gimple_eh_filter_failure (one));
3196 break;
3197 case GIMPLE_EH_ELSE:
3199 geh_else *eh_else_stmt = as_a <geh_else *> (one);
3200 refactor_eh_r (gimple_eh_else_n_body (eh_else_stmt));
3201 refactor_eh_r (gimple_eh_else_e_body (eh_else_stmt));
3203 break;
3204 default:
3205 break;
3207 if (two)
3208 gsi_next (&gsi);
3209 else
3210 break;
3214 namespace {
3216 const pass_data pass_data_refactor_eh =
3218 GIMPLE_PASS, /* type */
3219 "ehopt", /* name */
3220 OPTGROUP_NONE, /* optinfo_flags */
3221 TV_TREE_EH, /* tv_id */
3222 PROP_gimple_lcf, /* properties_required */
3223 0, /* properties_provided */
3224 0, /* properties_destroyed */
3225 0, /* todo_flags_start */
3226 0, /* todo_flags_finish */
3229 class pass_refactor_eh : public gimple_opt_pass
3231 public:
3232 pass_refactor_eh (gcc::context *ctxt)
3233 : gimple_opt_pass (pass_data_refactor_eh, ctxt)
3236 /* opt_pass methods: */
3237 virtual bool gate (function *) { return flag_exceptions != 0; }
3238 virtual unsigned int execute (function *)
3240 refactor_eh_r (gimple_body (current_function_decl));
3241 return 0;
3244 }; // class pass_refactor_eh
3246 } // anon namespace
3248 gimple_opt_pass *
3249 make_pass_refactor_eh (gcc::context *ctxt)
3251 return new pass_refactor_eh (ctxt);
3254 /* At the end of gimple optimization, we can lower RESX. */
3256 static bool
3257 lower_resx (basic_block bb, gresx *stmt,
3258 hash_map<eh_region, tree> *mnt_map)
3260 int lp_nr;
3261 eh_region src_r, dst_r;
3262 gimple_stmt_iterator gsi;
3263 gimple *x;
3264 tree fn, src_nr;
3265 bool ret = false;
3267 lp_nr = lookup_stmt_eh_lp (stmt);
3268 if (lp_nr != 0)
3269 dst_r = get_eh_region_from_lp_number (lp_nr);
3270 else
3271 dst_r = NULL;
3273 src_r = get_eh_region_from_number (gimple_resx_region (stmt));
3274 gsi = gsi_last_bb (bb);
3276 if (src_r == NULL)
3278 /* We can wind up with no source region when pass_cleanup_eh shows
3279 that there are no entries into an eh region and deletes it, but
3280 then the block that contains the resx isn't removed. This can
3281 happen without optimization when the switch statement created by
3282 lower_try_finally_switch isn't simplified to remove the eh case.
3284 Resolve this by expanding the resx node to an abort. */
3286 fn = builtin_decl_implicit (BUILT_IN_TRAP);
3287 x = gimple_build_call (fn, 0);
3288 gsi_insert_before (&gsi, x, GSI_SAME_STMT);
3290 while (EDGE_COUNT (bb->succs) > 0)
3291 remove_edge (EDGE_SUCC (bb, 0));
3293 else if (dst_r)
3295 /* When we have a destination region, we resolve this by copying
3296 the excptr and filter values into place, and changing the edge
3297 to immediately after the landing pad. */
3298 edge e;
3300 if (lp_nr < 0)
3302 basic_block new_bb;
3303 tree lab;
3305 /* We are resuming into a MUST_NOT_CALL region. Expand a call to
3306 the failure decl into a new block, if needed. */
3307 gcc_assert (dst_r->type == ERT_MUST_NOT_THROW);
3309 tree *slot = mnt_map->get (dst_r);
3310 if (slot == NULL)
3312 gimple_stmt_iterator gsi2;
3314 new_bb = create_empty_bb (bb);
3315 new_bb->count = bb->count;
3316 add_bb_to_loop (new_bb, bb->loop_father);
3317 lab = gimple_block_label (new_bb);
3318 gsi2 = gsi_start_bb (new_bb);
3320 fn = dst_r->u.must_not_throw.failure_decl;
3321 x = gimple_build_call (fn, 0);
3322 gimple_set_location (x, dst_r->u.must_not_throw.failure_loc);
3323 gsi_insert_after (&gsi2, x, GSI_CONTINUE_LINKING);
3325 mnt_map->put (dst_r, lab);
3327 else
3329 lab = *slot;
3330 new_bb = label_to_block (lab);
3333 gcc_assert (EDGE_COUNT (bb->succs) == 0);
3334 e = make_single_succ_edge (bb, new_bb, EDGE_FALLTHRU);
3336 else
3338 edge_iterator ei;
3339 tree dst_nr = build_int_cst (integer_type_node, dst_r->index);
3341 fn = builtin_decl_implicit (BUILT_IN_EH_COPY_VALUES);
3342 src_nr = build_int_cst (integer_type_node, src_r->index);
3343 x = gimple_build_call (fn, 2, dst_nr, src_nr);
3344 gsi_insert_before (&gsi, x, GSI_SAME_STMT);
3346 /* Update the flags for the outgoing edge. */
3347 e = single_succ_edge (bb);
3348 gcc_assert (e->flags & EDGE_EH);
3349 e->flags = (e->flags & ~EDGE_EH) | EDGE_FALLTHRU;
3350 e->probability = profile_probability::always ();
3352 /* If there are no more EH users of the landing pad, delete it. */
3353 FOR_EACH_EDGE (e, ei, e->dest->preds)
3354 if (e->flags & EDGE_EH)
3355 break;
3356 if (e == NULL)
3358 eh_landing_pad lp = get_eh_landing_pad_from_number (lp_nr);
3359 remove_eh_landing_pad (lp);
3363 ret = true;
3365 else
3367 tree var;
3369 /* When we don't have a destination region, this exception escapes
3370 up the call chain. We resolve this by generating a call to the
3371 _Unwind_Resume library function. */
3373 /* The ARM EABI redefines _Unwind_Resume as __cxa_end_cleanup
3374 with no arguments for C++. Check for that. */
3375 if (src_r->use_cxa_end_cleanup)
3377 fn = builtin_decl_implicit (BUILT_IN_CXA_END_CLEANUP);
3378 x = gimple_build_call (fn, 0);
3379 gsi_insert_before (&gsi, x, GSI_SAME_STMT);
3381 else
3383 fn = builtin_decl_implicit (BUILT_IN_EH_POINTER);
3384 src_nr = build_int_cst (integer_type_node, src_r->index);
3385 x = gimple_build_call (fn, 1, src_nr);
3386 var = create_tmp_var (ptr_type_node);
3387 var = make_ssa_name (var, x);
3388 gimple_call_set_lhs (x, var);
3389 gsi_insert_before (&gsi, x, GSI_SAME_STMT);
3391 /* When exception handling is delegated to a caller function, we
3392 have to guarantee that shadow memory variables living on stack
3393 will be cleaner before control is given to a parent function. */
3394 if (sanitize_flags_p (SANITIZE_ADDRESS))
3396 tree decl
3397 = builtin_decl_implicit (BUILT_IN_ASAN_HANDLE_NO_RETURN);
3398 gimple *g = gimple_build_call (decl, 0);
3399 gimple_set_location (g, gimple_location (stmt));
3400 gsi_insert_before (&gsi, g, GSI_SAME_STMT);
3403 fn = builtin_decl_implicit (BUILT_IN_UNWIND_RESUME);
3404 x = gimple_build_call (fn, 1, var);
3405 gsi_insert_before (&gsi, x, GSI_SAME_STMT);
3408 gcc_assert (EDGE_COUNT (bb->succs) == 0);
3411 gsi_remove (&gsi, true);
3413 return ret;
3416 namespace {
3418 const pass_data pass_data_lower_resx =
3420 GIMPLE_PASS, /* type */
3421 "resx", /* name */
3422 OPTGROUP_NONE, /* optinfo_flags */
3423 TV_TREE_EH, /* tv_id */
3424 PROP_gimple_lcf, /* properties_required */
3425 0, /* properties_provided */
3426 0, /* properties_destroyed */
3427 0, /* todo_flags_start */
3428 0, /* todo_flags_finish */
3431 class pass_lower_resx : public gimple_opt_pass
3433 public:
3434 pass_lower_resx (gcc::context *ctxt)
3435 : gimple_opt_pass (pass_data_lower_resx, ctxt)
3438 /* opt_pass methods: */
3439 virtual bool gate (function *) { return flag_exceptions != 0; }
3440 virtual unsigned int execute (function *);
3442 }; // class pass_lower_resx
3444 unsigned
3445 pass_lower_resx::execute (function *fun)
3447 basic_block bb;
3448 bool dominance_invalidated = false;
3449 bool any_rewritten = false;
3451 hash_map<eh_region, tree> mnt_map;
3453 FOR_EACH_BB_FN (bb, fun)
3455 gimple *last = last_stmt (bb);
3456 if (last && is_gimple_resx (last))
3458 dominance_invalidated |=
3459 lower_resx (bb, as_a <gresx *> (last), &mnt_map);
3460 any_rewritten = true;
3464 if (dominance_invalidated)
3466 free_dominance_info (CDI_DOMINATORS);
3467 free_dominance_info (CDI_POST_DOMINATORS);
3470 return any_rewritten ? TODO_update_ssa_only_virtuals : 0;
3473 } // anon namespace
3475 gimple_opt_pass *
3476 make_pass_lower_resx (gcc::context *ctxt)
3478 return new pass_lower_resx (ctxt);
3481 /* Try to optimize var = {v} {CLOBBER} stmts followed just by
3482 external throw. */
3484 static void
3485 optimize_clobbers (basic_block bb)
3487 gimple_stmt_iterator gsi = gsi_last_bb (bb);
3488 bool any_clobbers = false;
3489 bool seen_stack_restore = false;
3490 edge_iterator ei;
3491 edge e;
3493 /* Only optimize anything if the bb contains at least one clobber,
3494 ends with resx (checked by caller), optionally contains some
3495 debug stmts or labels, or at most one __builtin_stack_restore
3496 call, and has an incoming EH edge. */
3497 for (gsi_prev (&gsi); !gsi_end_p (gsi); gsi_prev (&gsi))
3499 gimple *stmt = gsi_stmt (gsi);
3500 if (is_gimple_debug (stmt))
3501 continue;
3502 if (gimple_clobber_p (stmt))
3504 any_clobbers = true;
3505 continue;
3507 if (!seen_stack_restore
3508 && gimple_call_builtin_p (stmt, BUILT_IN_STACK_RESTORE))
3510 seen_stack_restore = true;
3511 continue;
3513 if (gimple_code (stmt) == GIMPLE_LABEL)
3514 break;
3515 return;
3517 if (!any_clobbers)
3518 return;
3519 FOR_EACH_EDGE (e, ei, bb->preds)
3520 if (e->flags & EDGE_EH)
3521 break;
3522 if (e == NULL)
3523 return;
3524 gsi = gsi_last_bb (bb);
3525 for (gsi_prev (&gsi); !gsi_end_p (gsi); gsi_prev (&gsi))
3527 gimple *stmt = gsi_stmt (gsi);
3528 if (!gimple_clobber_p (stmt))
3529 continue;
3530 unlink_stmt_vdef (stmt);
3531 gsi_remove (&gsi, true);
3532 release_defs (stmt);
3536 /* Try to sink var = {v} {CLOBBER} stmts followed just by
3537 internal throw to successor BB. */
3539 static int
3540 sink_clobbers (basic_block bb)
3542 edge e;
3543 edge_iterator ei;
3544 gimple_stmt_iterator gsi, dgsi;
3545 basic_block succbb;
3546 bool any_clobbers = false;
3547 unsigned todo = 0;
3549 /* Only optimize if BB has a single EH successor and
3550 all predecessor edges are EH too. */
3551 if (!single_succ_p (bb)
3552 || (single_succ_edge (bb)->flags & EDGE_EH) == 0)
3553 return 0;
3555 FOR_EACH_EDGE (e, ei, bb->preds)
3557 if ((e->flags & EDGE_EH) == 0)
3558 return 0;
3561 /* And BB contains only CLOBBER stmts before the final
3562 RESX. */
3563 gsi = gsi_last_bb (bb);
3564 for (gsi_prev (&gsi); !gsi_end_p (gsi); gsi_prev (&gsi))
3566 gimple *stmt = gsi_stmt (gsi);
3567 if (is_gimple_debug (stmt))
3568 continue;
3569 if (gimple_code (stmt) == GIMPLE_LABEL)
3570 break;
3571 if (!gimple_clobber_p (stmt))
3572 return 0;
3573 any_clobbers = true;
3575 if (!any_clobbers)
3576 return 0;
3578 edge succe = single_succ_edge (bb);
3579 succbb = succe->dest;
3581 /* See if there is a virtual PHI node to take an updated virtual
3582 operand from. */
3583 gphi *vphi = NULL;
3584 tree vuse = NULL_TREE;
3585 for (gphi_iterator gpi = gsi_start_phis (succbb);
3586 !gsi_end_p (gpi); gsi_next (&gpi))
3588 tree res = gimple_phi_result (gpi.phi ());
3589 if (virtual_operand_p (res))
3591 vphi = gpi.phi ();
3592 vuse = res;
3593 break;
3597 dgsi = gsi_after_labels (succbb);
3598 gsi = gsi_last_bb (bb);
3599 for (gsi_prev (&gsi); !gsi_end_p (gsi); gsi_prev (&gsi))
3601 gimple *stmt = gsi_stmt (gsi);
3602 tree lhs;
3603 if (is_gimple_debug (stmt))
3604 continue;
3605 if (gimple_code (stmt) == GIMPLE_LABEL)
3606 break;
3607 lhs = gimple_assign_lhs (stmt);
3608 /* Unfortunately we don't have dominance info updated at this
3609 point, so checking if
3610 dominated_by_p (CDI_DOMINATORS, succbb,
3611 gimple_bb (SSA_NAME_DEF_STMT (TREE_OPERAND (lhs, 0)))
3612 would be too costly. Thus, avoid sinking any clobbers that
3613 refer to non-(D) SSA_NAMEs. */
3614 if (TREE_CODE (lhs) == MEM_REF
3615 && TREE_CODE (TREE_OPERAND (lhs, 0)) == SSA_NAME
3616 && !SSA_NAME_IS_DEFAULT_DEF (TREE_OPERAND (lhs, 0)))
3618 unlink_stmt_vdef (stmt);
3619 gsi_remove (&gsi, true);
3620 release_defs (stmt);
3621 continue;
3624 /* As we do not change stmt order when sinking across a
3625 forwarder edge we can keep virtual operands in place. */
3626 gsi_remove (&gsi, false);
3627 gsi_insert_before (&dgsi, stmt, GSI_NEW_STMT);
3629 /* But adjust virtual operands if we sunk across a PHI node. */
3630 if (vuse)
3632 gimple *use_stmt;
3633 imm_use_iterator iter;
3634 use_operand_p use_p;
3635 FOR_EACH_IMM_USE_STMT (use_stmt, iter, vuse)
3636 FOR_EACH_IMM_USE_ON_STMT (use_p, iter)
3637 SET_USE (use_p, gimple_vdef (stmt));
3638 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (vuse))
3640 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (gimple_vdef (stmt)) = 1;
3641 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (vuse) = 0;
3643 /* Adjust the incoming virtual operand. */
3644 SET_USE (PHI_ARG_DEF_PTR_FROM_EDGE (vphi, succe), gimple_vuse (stmt));
3645 SET_USE (gimple_vuse_op (stmt), vuse);
3647 /* If there isn't a single predecessor but no virtual PHI node
3648 arrange for virtual operands to be renamed. */
3649 else if (gimple_vuse_op (stmt) != NULL_USE_OPERAND_P
3650 && !single_pred_p (succbb))
3652 /* In this case there will be no use of the VDEF of this stmt.
3653 ??? Unless this is a secondary opportunity and we have not
3654 removed unreachable blocks yet, so we cannot assert this.
3655 Which also means we will end up renaming too many times. */
3656 SET_USE (gimple_vuse_op (stmt), gimple_vop (cfun));
3657 mark_virtual_operands_for_renaming (cfun);
3658 todo |= TODO_update_ssa_only_virtuals;
3662 return todo;
3665 /* At the end of inlining, we can lower EH_DISPATCH. Return true when
3666 we have found some duplicate labels and removed some edges. */
3668 static bool
3669 lower_eh_dispatch (basic_block src, geh_dispatch *stmt)
3671 gimple_stmt_iterator gsi;
3672 int region_nr;
3673 eh_region r;
3674 tree filter, fn;
3675 gimple *x;
3676 bool redirected = false;
3678 region_nr = gimple_eh_dispatch_region (stmt);
3679 r = get_eh_region_from_number (region_nr);
3681 gsi = gsi_last_bb (src);
3683 switch (r->type)
3685 case ERT_TRY:
3687 auto_vec<tree> labels;
3688 tree default_label = NULL;
3689 eh_catch c;
3690 edge_iterator ei;
3691 edge e;
3692 hash_set<tree> seen_values;
3694 /* Collect the labels for a switch. Zero the post_landing_pad
3695 field becase we'll no longer have anything keeping these labels
3696 in existence and the optimizer will be free to merge these
3697 blocks at will. */
3698 for (c = r->u.eh_try.first_catch; c ; c = c->next_catch)
3700 tree tp_node, flt_node, lab = c->label;
3701 bool have_label = false;
3703 c->label = NULL;
3704 tp_node = c->type_list;
3705 flt_node = c->filter_list;
3707 if (tp_node == NULL)
3709 default_label = lab;
3710 break;
3714 /* Filter out duplicate labels that arise when this handler
3715 is shadowed by an earlier one. When no labels are
3716 attached to the handler anymore, we remove
3717 the corresponding edge and then we delete unreachable
3718 blocks at the end of this pass. */
3719 if (! seen_values.contains (TREE_VALUE (flt_node)))
3721 tree t = build_case_label (TREE_VALUE (flt_node),
3722 NULL, lab);
3723 labels.safe_push (t);
3724 seen_values.add (TREE_VALUE (flt_node));
3725 have_label = true;
3728 tp_node = TREE_CHAIN (tp_node);
3729 flt_node = TREE_CHAIN (flt_node);
3731 while (tp_node);
3732 if (! have_label)
3734 remove_edge (find_edge (src, label_to_block (lab)));
3735 redirected = true;
3739 /* Clean up the edge flags. */
3740 FOR_EACH_EDGE (e, ei, src->succs)
3742 if (e->flags & EDGE_FALLTHRU)
3744 /* If there was no catch-all, use the fallthru edge. */
3745 if (default_label == NULL)
3746 default_label = gimple_block_label (e->dest);
3747 e->flags &= ~EDGE_FALLTHRU;
3750 gcc_assert (default_label != NULL);
3752 /* Don't generate a switch if there's only a default case.
3753 This is common in the form of try { A; } catch (...) { B; }. */
3754 if (!labels.exists ())
3756 e = single_succ_edge (src);
3757 e->flags |= EDGE_FALLTHRU;
3759 else
3761 fn = builtin_decl_implicit (BUILT_IN_EH_FILTER);
3762 x = gimple_build_call (fn, 1, build_int_cst (integer_type_node,
3763 region_nr));
3764 filter = create_tmp_var (TREE_TYPE (TREE_TYPE (fn)));
3765 filter = make_ssa_name (filter, x);
3766 gimple_call_set_lhs (x, filter);
3767 gsi_insert_before (&gsi, x, GSI_SAME_STMT);
3769 /* Turn the default label into a default case. */
3770 default_label = build_case_label (NULL, NULL, default_label);
3771 sort_case_labels (labels);
3773 x = gimple_build_switch (filter, default_label, labels);
3774 gsi_insert_before (&gsi, x, GSI_SAME_STMT);
3777 break;
3779 case ERT_ALLOWED_EXCEPTIONS:
3781 edge b_e = BRANCH_EDGE (src);
3782 edge f_e = FALLTHRU_EDGE (src);
3784 fn = builtin_decl_implicit (BUILT_IN_EH_FILTER);
3785 x = gimple_build_call (fn, 1, build_int_cst (integer_type_node,
3786 region_nr));
3787 filter = create_tmp_var (TREE_TYPE (TREE_TYPE (fn)));
3788 filter = make_ssa_name (filter, x);
3789 gimple_call_set_lhs (x, filter);
3790 gsi_insert_before (&gsi, x, GSI_SAME_STMT);
3792 r->u.allowed.label = NULL;
3793 x = gimple_build_cond (EQ_EXPR, filter,
3794 build_int_cst (TREE_TYPE (filter),
3795 r->u.allowed.filter),
3796 NULL_TREE, NULL_TREE);
3797 gsi_insert_before (&gsi, x, GSI_SAME_STMT);
3799 b_e->flags = b_e->flags | EDGE_TRUE_VALUE;
3800 f_e->flags = (f_e->flags & ~EDGE_FALLTHRU) | EDGE_FALSE_VALUE;
3802 break;
3804 default:
3805 gcc_unreachable ();
3808 /* Replace the EH_DISPATCH with the SWITCH or COND generated above. */
3809 gsi_remove (&gsi, true);
3810 return redirected;
3813 namespace {
3815 const pass_data pass_data_lower_eh_dispatch =
3817 GIMPLE_PASS, /* type */
3818 "ehdisp", /* name */
3819 OPTGROUP_NONE, /* optinfo_flags */
3820 TV_TREE_EH, /* tv_id */
3821 PROP_gimple_lcf, /* properties_required */
3822 0, /* properties_provided */
3823 0, /* properties_destroyed */
3824 0, /* todo_flags_start */
3825 0, /* todo_flags_finish */
3828 class pass_lower_eh_dispatch : public gimple_opt_pass
3830 public:
3831 pass_lower_eh_dispatch (gcc::context *ctxt)
3832 : gimple_opt_pass (pass_data_lower_eh_dispatch, ctxt)
3835 /* opt_pass methods: */
3836 virtual bool gate (function *fun) { return fun->eh->region_tree != NULL; }
3837 virtual unsigned int execute (function *);
3839 }; // class pass_lower_eh_dispatch
3841 unsigned
3842 pass_lower_eh_dispatch::execute (function *fun)
3844 basic_block bb;
3845 int flags = 0;
3846 bool redirected = false;
3848 assign_filter_values ();
3850 FOR_EACH_BB_FN (bb, fun)
3852 gimple *last = last_stmt (bb);
3853 if (last == NULL)
3854 continue;
3855 if (gimple_code (last) == GIMPLE_EH_DISPATCH)
3857 redirected |= lower_eh_dispatch (bb,
3858 as_a <geh_dispatch *> (last));
3859 flags |= TODO_update_ssa_only_virtuals;
3861 else if (gimple_code (last) == GIMPLE_RESX)
3863 if (stmt_can_throw_external (last))
3864 optimize_clobbers (bb);
3865 else
3866 flags |= sink_clobbers (bb);
3870 if (redirected)
3872 free_dominance_info (CDI_DOMINATORS);
3873 delete_unreachable_blocks ();
3875 return flags;
3878 } // anon namespace
3880 gimple_opt_pass *
3881 make_pass_lower_eh_dispatch (gcc::context *ctxt)
3883 return new pass_lower_eh_dispatch (ctxt);
3886 /* Walk statements, see what regions and, optionally, landing pads
3887 are really referenced.
3889 Returns in R_REACHABLEP an sbitmap with bits set for reachable regions,
3890 and in LP_REACHABLE an sbitmap with bits set for reachable landing pads.
3892 Passing NULL for LP_REACHABLE is valid, in this case only reachable
3893 regions are marked.
3895 The caller is responsible for freeing the returned sbitmaps. */
3897 static void
3898 mark_reachable_handlers (sbitmap *r_reachablep, sbitmap *lp_reachablep)
3900 sbitmap r_reachable, lp_reachable;
3901 basic_block bb;
3902 bool mark_landing_pads = (lp_reachablep != NULL);
3903 gcc_checking_assert (r_reachablep != NULL);
3905 r_reachable = sbitmap_alloc (cfun->eh->region_array->length ());
3906 bitmap_clear (r_reachable);
3907 *r_reachablep = r_reachable;
3909 if (mark_landing_pads)
3911 lp_reachable = sbitmap_alloc (cfun->eh->lp_array->length ());
3912 bitmap_clear (lp_reachable);
3913 *lp_reachablep = lp_reachable;
3915 else
3916 lp_reachable = NULL;
3918 FOR_EACH_BB_FN (bb, cfun)
3920 gimple_stmt_iterator gsi;
3922 for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
3924 gimple *stmt = gsi_stmt (gsi);
3926 if (mark_landing_pads)
3928 int lp_nr = lookup_stmt_eh_lp (stmt);
3930 /* Negative LP numbers are MUST_NOT_THROW regions which
3931 are not considered BB enders. */
3932 if (lp_nr < 0)
3933 bitmap_set_bit (r_reachable, -lp_nr);
3935 /* Positive LP numbers are real landing pads, and BB enders. */
3936 else if (lp_nr > 0)
3938 gcc_assert (gsi_one_before_end_p (gsi));
3939 eh_region region = get_eh_region_from_lp_number (lp_nr);
3940 bitmap_set_bit (r_reachable, region->index);
3941 bitmap_set_bit (lp_reachable, lp_nr);
3945 /* Avoid removing regions referenced from RESX/EH_DISPATCH. */
3946 switch (gimple_code (stmt))
3948 case GIMPLE_RESX:
3949 bitmap_set_bit (r_reachable,
3950 gimple_resx_region (as_a <gresx *> (stmt)));
3951 break;
3952 case GIMPLE_EH_DISPATCH:
3953 bitmap_set_bit (r_reachable,
3954 gimple_eh_dispatch_region (
3955 as_a <geh_dispatch *> (stmt)));
3956 break;
3957 case GIMPLE_CALL:
3958 if (gimple_call_builtin_p (stmt, BUILT_IN_EH_COPY_VALUES))
3959 for (int i = 0; i < 2; ++i)
3961 tree rt = gimple_call_arg (stmt, i);
3962 HOST_WIDE_INT ri = tree_to_shwi (rt);
3964 gcc_assert (ri == (int)ri);
3965 bitmap_set_bit (r_reachable, ri);
3967 break;
3968 default:
3969 break;
3975 /* Remove unreachable handlers and unreachable landing pads. */
3977 static void
3978 remove_unreachable_handlers (void)
3980 sbitmap r_reachable, lp_reachable;
3981 eh_region region;
3982 eh_landing_pad lp;
3983 unsigned i;
3985 mark_reachable_handlers (&r_reachable, &lp_reachable);
3987 if (dump_file)
3989 fprintf (dump_file, "Before removal of unreachable regions:\n");
3990 dump_eh_tree (dump_file, cfun);
3991 fprintf (dump_file, "Reachable regions: ");
3992 dump_bitmap_file (dump_file, r_reachable);
3993 fprintf (dump_file, "Reachable landing pads: ");
3994 dump_bitmap_file (dump_file, lp_reachable);
3997 if (dump_file)
3999 FOR_EACH_VEC_SAFE_ELT (cfun->eh->region_array, i, region)
4000 if (region && !bitmap_bit_p (r_reachable, region->index))
4001 fprintf (dump_file,
4002 "Removing unreachable region %d\n",
4003 region->index);
4006 remove_unreachable_eh_regions (r_reachable);
4008 FOR_EACH_VEC_SAFE_ELT (cfun->eh->lp_array, i, lp)
4009 if (lp && !bitmap_bit_p (lp_reachable, lp->index))
4011 if (dump_file)
4012 fprintf (dump_file,
4013 "Removing unreachable landing pad %d\n",
4014 lp->index);
4015 remove_eh_landing_pad (lp);
4018 if (dump_file)
4020 fprintf (dump_file, "\n\nAfter removal of unreachable regions:\n");
4021 dump_eh_tree (dump_file, cfun);
4022 fprintf (dump_file, "\n\n");
4025 sbitmap_free (r_reachable);
4026 sbitmap_free (lp_reachable);
4028 if (flag_checking)
4029 verify_eh_tree (cfun);
4032 /* Remove unreachable handlers if any landing pads have been removed after
4033 last ehcleanup pass (due to gimple_purge_dead_eh_edges). */
4035 void
4036 maybe_remove_unreachable_handlers (void)
4038 eh_landing_pad lp;
4039 unsigned i;
4041 if (cfun->eh == NULL)
4042 return;
4044 FOR_EACH_VEC_SAFE_ELT (cfun->eh->lp_array, i, lp)
4045 if (lp && lp->post_landing_pad)
4047 if (label_to_block (lp->post_landing_pad) == NULL)
4049 remove_unreachable_handlers ();
4050 return;
4055 /* Remove regions that do not have landing pads. This assumes
4056 that remove_unreachable_handlers has already been run, and
4057 that we've just manipulated the landing pads since then.
4059 Preserve regions with landing pads and regions that prevent
4060 exceptions from propagating further, even if these regions
4061 are not reachable. */
4063 static void
4064 remove_unreachable_handlers_no_lp (void)
4066 eh_region region;
4067 sbitmap r_reachable;
4068 unsigned i;
4070 mark_reachable_handlers (&r_reachable, /*lp_reachablep=*/NULL);
4072 FOR_EACH_VEC_SAFE_ELT (cfun->eh->region_array, i, region)
4074 if (! region)
4075 continue;
4077 if (region->landing_pads != NULL
4078 || region->type == ERT_MUST_NOT_THROW)
4079 bitmap_set_bit (r_reachable, region->index);
4081 if (dump_file
4082 && !bitmap_bit_p (r_reachable, region->index))
4083 fprintf (dump_file,
4084 "Removing unreachable region %d\n",
4085 region->index);
4088 remove_unreachable_eh_regions (r_reachable);
4090 sbitmap_free (r_reachable);
4093 /* Undo critical edge splitting on an EH landing pad. Earlier, we
4094 optimisticaly split all sorts of edges, including EH edges. The
4095 optimization passes in between may not have needed them; if not,
4096 we should undo the split.
4098 Recognize this case by having one EH edge incoming to the BB and
4099 one normal edge outgoing; BB should be empty apart from the
4100 post_landing_pad label.
4102 Note that this is slightly different from the empty handler case
4103 handled by cleanup_empty_eh, in that the actual handler may yet
4104 have actual code but the landing pad has been separated from the
4105 handler. As such, cleanup_empty_eh relies on this transformation
4106 having been done first. */
4108 static bool
4109 unsplit_eh (eh_landing_pad lp)
4111 basic_block bb = label_to_block (lp->post_landing_pad);
4112 gimple_stmt_iterator gsi;
4113 edge e_in, e_out;
4115 /* Quickly check the edge counts on BB for singularity. */
4116 if (!single_pred_p (bb) || !single_succ_p (bb))
4117 return false;
4118 e_in = single_pred_edge (bb);
4119 e_out = single_succ_edge (bb);
4121 /* Input edge must be EH and output edge must be normal. */
4122 if ((e_in->flags & EDGE_EH) == 0 || (e_out->flags & EDGE_EH) != 0)
4123 return false;
4125 /* The block must be empty except for the labels and debug insns. */
4126 gsi = gsi_after_labels (bb);
4127 if (!gsi_end_p (gsi) && is_gimple_debug (gsi_stmt (gsi)))
4128 gsi_next_nondebug (&gsi);
4129 if (!gsi_end_p (gsi))
4130 return false;
4132 /* The destination block must not already have a landing pad
4133 for a different region. */
4134 for (gsi = gsi_start_bb (e_out->dest); !gsi_end_p (gsi); gsi_next (&gsi))
4136 glabel *label_stmt = dyn_cast <glabel *> (gsi_stmt (gsi));
4137 tree lab;
4138 int lp_nr;
4140 if (!label_stmt)
4141 break;
4142 lab = gimple_label_label (label_stmt);
4143 lp_nr = EH_LANDING_PAD_NR (lab);
4144 if (lp_nr && get_eh_region_from_lp_number (lp_nr) != lp->region)
4145 return false;
4148 /* The new destination block must not already be a destination of
4149 the source block, lest we merge fallthru and eh edges and get
4150 all sorts of confused. */
4151 if (find_edge (e_in->src, e_out->dest))
4152 return false;
4154 /* ??? We can get degenerate phis due to cfg cleanups. I would have
4155 thought this should have been cleaned up by a phicprop pass, but
4156 that doesn't appear to handle virtuals. Propagate by hand. */
4157 if (!gimple_seq_empty_p (phi_nodes (bb)))
4159 for (gphi_iterator gpi = gsi_start_phis (bb); !gsi_end_p (gpi); )
4161 gimple *use_stmt;
4162 gphi *phi = gpi.phi ();
4163 tree lhs = gimple_phi_result (phi);
4164 tree rhs = gimple_phi_arg_def (phi, 0);
4165 use_operand_p use_p;
4166 imm_use_iterator iter;
4168 FOR_EACH_IMM_USE_STMT (use_stmt, iter, lhs)
4170 FOR_EACH_IMM_USE_ON_STMT (use_p, iter)
4171 SET_USE (use_p, rhs);
4174 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (lhs))
4175 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (rhs) = 1;
4177 remove_phi_node (&gpi, true);
4181 if (dump_file && (dump_flags & TDF_DETAILS))
4182 fprintf (dump_file, "Unsplit EH landing pad %d to block %i.\n",
4183 lp->index, e_out->dest->index);
4185 /* Redirect the edge. Since redirect_eh_edge_1 expects to be moving
4186 a successor edge, humor it. But do the real CFG change with the
4187 predecessor of E_OUT in order to preserve the ordering of arguments
4188 to the PHI nodes in E_OUT->DEST. */
4189 redirect_eh_edge_1 (e_in, e_out->dest, false);
4190 redirect_edge_pred (e_out, e_in->src);
4191 e_out->flags = e_in->flags;
4192 e_out->probability = e_in->probability;
4193 remove_edge (e_in);
4195 return true;
4198 /* Examine each landing pad block and see if it matches unsplit_eh. */
4200 static bool
4201 unsplit_all_eh (void)
4203 bool changed = false;
4204 eh_landing_pad lp;
4205 int i;
4207 for (i = 1; vec_safe_iterate (cfun->eh->lp_array, i, &lp); ++i)
4208 if (lp)
4209 changed |= unsplit_eh (lp);
4211 return changed;
4214 /* A subroutine of cleanup_empty_eh. Redirect all EH edges incoming
4215 to OLD_BB to NEW_BB; return true on success, false on failure.
4217 OLD_BB_OUT is the edge into NEW_BB from OLD_BB, so if we miss any
4218 PHI variables from OLD_BB we can pick them up from OLD_BB_OUT.
4219 Virtual PHIs may be deleted and marked for renaming. */
4221 static bool
4222 cleanup_empty_eh_merge_phis (basic_block new_bb, basic_block old_bb,
4223 edge old_bb_out, bool change_region)
4225 gphi_iterator ngsi, ogsi;
4226 edge_iterator ei;
4227 edge e;
4228 bitmap ophi_handled;
4230 /* The destination block must not be a regular successor for any
4231 of the preds of the landing pad. Thus, avoid turning
4232 <..>
4233 | \ EH
4234 | <..>
4236 <..>
4237 into
4238 <..>
4239 | | EH
4240 <..>
4241 which CFG verification would choke on. See PR45172 and PR51089. */
4242 FOR_EACH_EDGE (e, ei, old_bb->preds)
4243 if (find_edge (e->src, new_bb))
4244 return false;
4246 FOR_EACH_EDGE (e, ei, old_bb->preds)
4247 redirect_edge_var_map_clear (e);
4249 ophi_handled = BITMAP_ALLOC (NULL);
4251 /* First, iterate through the PHIs on NEW_BB and set up the edge_var_map
4252 for the edges we're going to move. */
4253 for (ngsi = gsi_start_phis (new_bb); !gsi_end_p (ngsi); gsi_next (&ngsi))
4255 gphi *ophi, *nphi = ngsi.phi ();
4256 tree nresult, nop;
4258 nresult = gimple_phi_result (nphi);
4259 nop = gimple_phi_arg_def (nphi, old_bb_out->dest_idx);
4261 /* Find the corresponding PHI in OLD_BB so we can forward-propagate
4262 the source ssa_name. */
4263 ophi = NULL;
4264 for (ogsi = gsi_start_phis (old_bb); !gsi_end_p (ogsi); gsi_next (&ogsi))
4266 ophi = ogsi.phi ();
4267 if (gimple_phi_result (ophi) == nop)
4268 break;
4269 ophi = NULL;
4272 /* If we did find the corresponding PHI, copy those inputs. */
4273 if (ophi)
4275 /* If NOP is used somewhere else beyond phis in new_bb, give up. */
4276 if (!has_single_use (nop))
4278 imm_use_iterator imm_iter;
4279 use_operand_p use_p;
4281 FOR_EACH_IMM_USE_FAST (use_p, imm_iter, nop)
4283 if (!gimple_debug_bind_p (USE_STMT (use_p))
4284 && (gimple_code (USE_STMT (use_p)) != GIMPLE_PHI
4285 || gimple_bb (USE_STMT (use_p)) != new_bb))
4286 goto fail;
4289 bitmap_set_bit (ophi_handled, SSA_NAME_VERSION (nop));
4290 FOR_EACH_EDGE (e, ei, old_bb->preds)
4292 location_t oloc;
4293 tree oop;
4295 if ((e->flags & EDGE_EH) == 0)
4296 continue;
4297 oop = gimple_phi_arg_def (ophi, e->dest_idx);
4298 oloc = gimple_phi_arg_location (ophi, e->dest_idx);
4299 redirect_edge_var_map_add (e, nresult, oop, oloc);
4302 /* If we didn't find the PHI, if it's a real variable or a VOP, we know
4303 from the fact that OLD_BB is tree_empty_eh_handler_p that the
4304 variable is unchanged from input to the block and we can simply
4305 re-use the input to NEW_BB from the OLD_BB_OUT edge. */
4306 else
4308 location_t nloc
4309 = gimple_phi_arg_location (nphi, old_bb_out->dest_idx);
4310 FOR_EACH_EDGE (e, ei, old_bb->preds)
4311 redirect_edge_var_map_add (e, nresult, nop, nloc);
4315 /* Second, verify that all PHIs from OLD_BB have been handled. If not,
4316 we don't know what values from the other edges into NEW_BB to use. */
4317 for (ogsi = gsi_start_phis (old_bb); !gsi_end_p (ogsi); gsi_next (&ogsi))
4319 gphi *ophi = ogsi.phi ();
4320 tree oresult = gimple_phi_result (ophi);
4321 if (!bitmap_bit_p (ophi_handled, SSA_NAME_VERSION (oresult)))
4322 goto fail;
4325 /* Finally, move the edges and update the PHIs. */
4326 for (ei = ei_start (old_bb->preds); (e = ei_safe_edge (ei)); )
4327 if (e->flags & EDGE_EH)
4329 /* ??? CFG manipluation routines do not try to update loop
4330 form on edge redirection. Do so manually here for now. */
4331 /* If we redirect a loop entry or latch edge that will either create
4332 a multiple entry loop or rotate the loop. If the loops merge
4333 we may have created a loop with multiple latches.
4334 All of this isn't easily fixed thus cancel the affected loop
4335 and mark the other loop as possibly having multiple latches. */
4336 if (e->dest == e->dest->loop_father->header)
4338 mark_loop_for_removal (e->dest->loop_father);
4339 new_bb->loop_father->latch = NULL;
4340 loops_state_set (LOOPS_MAY_HAVE_MULTIPLE_LATCHES);
4342 redirect_eh_edge_1 (e, new_bb, change_region);
4343 redirect_edge_succ (e, new_bb);
4344 flush_pending_stmts (e);
4346 else
4347 ei_next (&ei);
4349 BITMAP_FREE (ophi_handled);
4350 return true;
4352 fail:
4353 FOR_EACH_EDGE (e, ei, old_bb->preds)
4354 redirect_edge_var_map_clear (e);
4355 BITMAP_FREE (ophi_handled);
4356 return false;
4359 /* A subroutine of cleanup_empty_eh. Move a landing pad LP from its
4360 old region to NEW_REGION at BB. */
4362 static void
4363 cleanup_empty_eh_move_lp (basic_block bb, edge e_out,
4364 eh_landing_pad lp, eh_region new_region)
4366 gimple_stmt_iterator gsi;
4367 eh_landing_pad *pp;
4369 for (pp = &lp->region->landing_pads; *pp != lp; pp = &(*pp)->next_lp)
4370 continue;
4371 *pp = lp->next_lp;
4373 lp->region = new_region;
4374 lp->next_lp = new_region->landing_pads;
4375 new_region->landing_pads = lp;
4377 /* Delete the RESX that was matched within the empty handler block. */
4378 gsi = gsi_last_bb (bb);
4379 unlink_stmt_vdef (gsi_stmt (gsi));
4380 gsi_remove (&gsi, true);
4382 /* Clean up E_OUT for the fallthru. */
4383 e_out->flags = (e_out->flags & ~EDGE_EH) | EDGE_FALLTHRU;
4384 e_out->probability = profile_probability::always ();
4387 /* A subroutine of cleanup_empty_eh. Handle more complex cases of
4388 unsplitting than unsplit_eh was prepared to handle, e.g. when
4389 multiple incoming edges and phis are involved. */
4391 static bool
4392 cleanup_empty_eh_unsplit (basic_block bb, edge e_out, eh_landing_pad lp)
4394 gimple_stmt_iterator gsi;
4395 tree lab;
4397 /* We really ought not have totally lost everything following
4398 a landing pad label. Given that BB is empty, there had better
4399 be a successor. */
4400 gcc_assert (e_out != NULL);
4402 /* The destination block must not already have a landing pad
4403 for a different region. */
4404 lab = NULL;
4405 for (gsi = gsi_start_bb (e_out->dest); !gsi_end_p (gsi); gsi_next (&gsi))
4407 glabel *stmt = dyn_cast <glabel *> (gsi_stmt (gsi));
4408 int lp_nr;
4410 if (!stmt)
4411 break;
4412 lab = gimple_label_label (stmt);
4413 lp_nr = EH_LANDING_PAD_NR (lab);
4414 if (lp_nr && get_eh_region_from_lp_number (lp_nr) != lp->region)
4415 return false;
4418 /* Attempt to move the PHIs into the successor block. */
4419 if (cleanup_empty_eh_merge_phis (e_out->dest, bb, e_out, false))
4421 if (dump_file && (dump_flags & TDF_DETAILS))
4422 fprintf (dump_file,
4423 "Unsplit EH landing pad %d to block %i "
4424 "(via cleanup_empty_eh).\n",
4425 lp->index, e_out->dest->index);
4426 return true;
4429 return false;
4432 /* Return true if edge E_FIRST is part of an empty infinite loop
4433 or leads to such a loop through a series of single successor
4434 empty bbs. */
4436 static bool
4437 infinite_empty_loop_p (edge e_first)
4439 bool inf_loop = false;
4440 edge e;
4442 if (e_first->dest == e_first->src)
4443 return true;
4445 e_first->src->aux = (void *) 1;
4446 for (e = e_first; single_succ_p (e->dest); e = single_succ_edge (e->dest))
4448 gimple_stmt_iterator gsi;
4449 if (e->dest->aux)
4451 inf_loop = true;
4452 break;
4454 e->dest->aux = (void *) 1;
4455 gsi = gsi_after_labels (e->dest);
4456 if (!gsi_end_p (gsi) && is_gimple_debug (gsi_stmt (gsi)))
4457 gsi_next_nondebug (&gsi);
4458 if (!gsi_end_p (gsi))
4459 break;
4461 e_first->src->aux = NULL;
4462 for (e = e_first; e->dest->aux; e = single_succ_edge (e->dest))
4463 e->dest->aux = NULL;
4465 return inf_loop;
4468 /* Examine the block associated with LP to determine if it's an empty
4469 handler for its EH region. If so, attempt to redirect EH edges to
4470 an outer region. Return true the CFG was updated in any way. This
4471 is similar to jump forwarding, just across EH edges. */
4473 static bool
4474 cleanup_empty_eh (eh_landing_pad lp)
4476 basic_block bb = label_to_block (lp->post_landing_pad);
4477 gimple_stmt_iterator gsi;
4478 gimple *resx;
4479 eh_region new_region;
4480 edge_iterator ei;
4481 edge e, e_out;
4482 bool has_non_eh_pred;
4483 bool ret = false;
4484 int new_lp_nr;
4486 /* There can be zero or one edges out of BB. This is the quickest test. */
4487 switch (EDGE_COUNT (bb->succs))
4489 case 0:
4490 e_out = NULL;
4491 break;
4492 case 1:
4493 e_out = single_succ_edge (bb);
4494 break;
4495 default:
4496 return false;
4499 gsi = gsi_last_nondebug_bb (bb);
4500 resx = gsi_stmt (gsi);
4501 if (resx && is_gimple_resx (resx))
4503 if (stmt_can_throw_external (resx))
4504 optimize_clobbers (bb);
4505 else if (sink_clobbers (bb))
4506 ret = true;
4509 gsi = gsi_after_labels (bb);
4511 /* Make sure to skip debug statements. */
4512 if (!gsi_end_p (gsi) && is_gimple_debug (gsi_stmt (gsi)))
4513 gsi_next_nondebug (&gsi);
4515 /* If the block is totally empty, look for more unsplitting cases. */
4516 if (gsi_end_p (gsi))
4518 /* For the degenerate case of an infinite loop bail out.
4519 If bb has no successors and is totally empty, which can happen e.g.
4520 because of incorrect noreturn attribute, bail out too. */
4521 if (e_out == NULL
4522 || infinite_empty_loop_p (e_out))
4523 return ret;
4525 return ret | cleanup_empty_eh_unsplit (bb, e_out, lp);
4528 /* The block should consist only of a single RESX statement, modulo a
4529 preceding call to __builtin_stack_restore if there is no outgoing
4530 edge, since the call can be eliminated in this case. */
4531 resx = gsi_stmt (gsi);
4532 if (!e_out && gimple_call_builtin_p (resx, BUILT_IN_STACK_RESTORE))
4534 gsi_next_nondebug (&gsi);
4535 resx = gsi_stmt (gsi);
4537 if (!is_gimple_resx (resx))
4538 return ret;
4539 gcc_assert (gsi_one_nondebug_before_end_p (gsi));
4541 /* Determine if there are non-EH edges, or resx edges into the handler. */
4542 has_non_eh_pred = false;
4543 FOR_EACH_EDGE (e, ei, bb->preds)
4544 if (!(e->flags & EDGE_EH))
4545 has_non_eh_pred = true;
4547 /* Find the handler that's outer of the empty handler by looking at
4548 where the RESX instruction was vectored. */
4549 new_lp_nr = lookup_stmt_eh_lp (resx);
4550 new_region = get_eh_region_from_lp_number (new_lp_nr);
4552 /* If there's no destination region within the current function,
4553 redirection is trivial via removing the throwing statements from
4554 the EH region, removing the EH edges, and allowing the block
4555 to go unreachable. */
4556 if (new_region == NULL)
4558 gcc_assert (e_out == NULL);
4559 for (ei = ei_start (bb->preds); (e = ei_safe_edge (ei)); )
4560 if (e->flags & EDGE_EH)
4562 gimple *stmt = last_stmt (e->src);
4563 remove_stmt_from_eh_lp (stmt);
4564 remove_edge (e);
4566 else
4567 ei_next (&ei);
4568 goto succeed;
4571 /* If the destination region is a MUST_NOT_THROW, allow the runtime
4572 to handle the abort and allow the blocks to go unreachable. */
4573 if (new_region->type == ERT_MUST_NOT_THROW)
4575 for (ei = ei_start (bb->preds); (e = ei_safe_edge (ei)); )
4576 if (e->flags & EDGE_EH)
4578 gimple *stmt = last_stmt (e->src);
4579 remove_stmt_from_eh_lp (stmt);
4580 add_stmt_to_eh_lp (stmt, new_lp_nr);
4581 remove_edge (e);
4583 else
4584 ei_next (&ei);
4585 goto succeed;
4588 /* Try to redirect the EH edges and merge the PHIs into the destination
4589 landing pad block. If the merge succeeds, we'll already have redirected
4590 all the EH edges. The handler itself will go unreachable if there were
4591 no normal edges. */
4592 if (cleanup_empty_eh_merge_phis (e_out->dest, bb, e_out, true))
4593 goto succeed;
4595 /* Finally, if all input edges are EH edges, then we can (potentially)
4596 reduce the number of transfers from the runtime by moving the landing
4597 pad from the original region to the new region. This is a win when
4598 we remove the last CLEANUP region along a particular exception
4599 propagation path. Since nothing changes except for the region with
4600 which the landing pad is associated, the PHI nodes do not need to be
4601 adjusted at all. */
4602 if (!has_non_eh_pred)
4604 cleanup_empty_eh_move_lp (bb, e_out, lp, new_region);
4605 if (dump_file && (dump_flags & TDF_DETAILS))
4606 fprintf (dump_file, "Empty EH handler %i moved to EH region %i.\n",
4607 lp->index, new_region->index);
4609 /* ??? The CFG didn't change, but we may have rendered the
4610 old EH region unreachable. Trigger a cleanup there. */
4611 return true;
4614 return ret;
4616 succeed:
4617 if (dump_file && (dump_flags & TDF_DETAILS))
4618 fprintf (dump_file, "Empty EH handler %i removed.\n", lp->index);
4619 remove_eh_landing_pad (lp);
4620 return true;
4623 /* Do a post-order traversal of the EH region tree. Examine each
4624 post_landing_pad block and see if we can eliminate it as empty. */
4626 static bool
4627 cleanup_all_empty_eh (void)
4629 bool changed = false;
4630 eh_landing_pad lp;
4631 int i;
4633 for (i = 1; vec_safe_iterate (cfun->eh->lp_array, i, &lp); ++i)
4634 if (lp)
4635 changed |= cleanup_empty_eh (lp);
4637 return changed;
4640 /* Perform cleanups and lowering of exception handling
4641 1) cleanups regions with handlers doing nothing are optimized out
4642 2) MUST_NOT_THROW regions that became dead because of 1) are optimized out
4643 3) Info about regions that are containing instructions, and regions
4644 reachable via local EH edges is collected
4645 4) Eh tree is pruned for regions no longer necessary.
4647 TODO: Push MUST_NOT_THROW regions to the root of the EH tree.
4648 Unify those that have the same failure decl and locus.
4651 static unsigned int
4652 execute_cleanup_eh_1 (void)
4654 /* Do this first: unsplit_all_eh and cleanup_all_empty_eh can die
4655 looking up unreachable landing pads. */
4656 remove_unreachable_handlers ();
4658 /* Watch out for the region tree vanishing due to all unreachable. */
4659 if (cfun->eh->region_tree)
4661 bool changed = false;
4663 if (optimize)
4664 changed |= unsplit_all_eh ();
4665 changed |= cleanup_all_empty_eh ();
4667 if (changed)
4669 free_dominance_info (CDI_DOMINATORS);
4670 free_dominance_info (CDI_POST_DOMINATORS);
4672 /* We delayed all basic block deletion, as we may have performed
4673 cleanups on EH edges while non-EH edges were still present. */
4674 delete_unreachable_blocks ();
4676 /* We manipulated the landing pads. Remove any region that no
4677 longer has a landing pad. */
4678 remove_unreachable_handlers_no_lp ();
4680 return TODO_cleanup_cfg | TODO_update_ssa_only_virtuals;
4684 return 0;
4687 namespace {
4689 const pass_data pass_data_cleanup_eh =
4691 GIMPLE_PASS, /* type */
4692 "ehcleanup", /* name */
4693 OPTGROUP_NONE, /* optinfo_flags */
4694 TV_TREE_EH, /* tv_id */
4695 PROP_gimple_lcf, /* properties_required */
4696 0, /* properties_provided */
4697 0, /* properties_destroyed */
4698 0, /* todo_flags_start */
4699 0, /* todo_flags_finish */
4702 class pass_cleanup_eh : public gimple_opt_pass
4704 public:
4705 pass_cleanup_eh (gcc::context *ctxt)
4706 : gimple_opt_pass (pass_data_cleanup_eh, ctxt)
4709 /* opt_pass methods: */
4710 opt_pass * clone () { return new pass_cleanup_eh (m_ctxt); }
4711 virtual bool gate (function *fun)
4713 return fun->eh != NULL && fun->eh->region_tree != NULL;
4716 virtual unsigned int execute (function *);
4718 }; // class pass_cleanup_eh
4720 unsigned int
4721 pass_cleanup_eh::execute (function *fun)
4723 int ret = execute_cleanup_eh_1 ();
4725 /* If the function no longer needs an EH personality routine
4726 clear it. This exposes cross-language inlining opportunities
4727 and avoids references to a never defined personality routine. */
4728 if (DECL_FUNCTION_PERSONALITY (current_function_decl)
4729 && function_needs_eh_personality (fun) != eh_personality_lang)
4730 DECL_FUNCTION_PERSONALITY (current_function_decl) = NULL_TREE;
4732 return ret;
4735 } // anon namespace
4737 gimple_opt_pass *
4738 make_pass_cleanup_eh (gcc::context *ctxt)
4740 return new pass_cleanup_eh (ctxt);
4743 /* Verify that BB containing STMT as the last statement, has precisely the
4744 edge that make_eh_edges would create. */
4746 DEBUG_FUNCTION bool
4747 verify_eh_edges (gimple *stmt)
4749 basic_block bb = gimple_bb (stmt);
4750 eh_landing_pad lp = NULL;
4751 int lp_nr;
4752 edge_iterator ei;
4753 edge e, eh_edge;
4755 lp_nr = lookup_stmt_eh_lp (stmt);
4756 if (lp_nr > 0)
4757 lp = get_eh_landing_pad_from_number (lp_nr);
4759 eh_edge = NULL;
4760 FOR_EACH_EDGE (e, ei, bb->succs)
4762 if (e->flags & EDGE_EH)
4764 if (eh_edge)
4766 error ("BB %i has multiple EH edges", bb->index);
4767 return true;
4769 else
4770 eh_edge = e;
4774 if (lp == NULL)
4776 if (eh_edge)
4778 error ("BB %i can not throw but has an EH edge", bb->index);
4779 return true;
4781 return false;
4784 if (!stmt_could_throw_p (stmt))
4786 error ("BB %i last statement has incorrectly set lp", bb->index);
4787 return true;
4790 if (eh_edge == NULL)
4792 error ("BB %i is missing an EH edge", bb->index);
4793 return true;
4796 if (eh_edge->dest != label_to_block (lp->post_landing_pad))
4798 error ("Incorrect EH edge %i->%i", bb->index, eh_edge->dest->index);
4799 return true;
4802 return false;
4805 /* Similarly, but handle GIMPLE_EH_DISPATCH specifically. */
4807 DEBUG_FUNCTION bool
4808 verify_eh_dispatch_edge (geh_dispatch *stmt)
4810 eh_region r;
4811 eh_catch c;
4812 basic_block src, dst;
4813 bool want_fallthru = true;
4814 edge_iterator ei;
4815 edge e, fall_edge;
4817 r = get_eh_region_from_number (gimple_eh_dispatch_region (stmt));
4818 src = gimple_bb (stmt);
4820 FOR_EACH_EDGE (e, ei, src->succs)
4821 gcc_assert (e->aux == NULL);
4823 switch (r->type)
4825 case ERT_TRY:
4826 for (c = r->u.eh_try.first_catch; c ; c = c->next_catch)
4828 dst = label_to_block (c->label);
4829 e = find_edge (src, dst);
4830 if (e == NULL)
4832 error ("BB %i is missing an edge", src->index);
4833 return true;
4835 e->aux = (void *)e;
4837 /* A catch-all handler doesn't have a fallthru. */
4838 if (c->type_list == NULL)
4840 want_fallthru = false;
4841 break;
4844 break;
4846 case ERT_ALLOWED_EXCEPTIONS:
4847 dst = label_to_block (r->u.allowed.label);
4848 e = find_edge (src, dst);
4849 if (e == NULL)
4851 error ("BB %i is missing an edge", src->index);
4852 return true;
4854 e->aux = (void *)e;
4855 break;
4857 default:
4858 gcc_unreachable ();
4861 fall_edge = NULL;
4862 FOR_EACH_EDGE (e, ei, src->succs)
4864 if (e->flags & EDGE_FALLTHRU)
4866 if (fall_edge != NULL)
4868 error ("BB %i too many fallthru edges", src->index);
4869 return true;
4871 fall_edge = e;
4873 else if (e->aux)
4874 e->aux = NULL;
4875 else
4877 error ("BB %i has incorrect edge", src->index);
4878 return true;
4881 if ((fall_edge != NULL) ^ want_fallthru)
4883 error ("BB %i has incorrect fallthru edge", src->index);
4884 return true;
4887 return false;