1 /* Exception handling semantics and decomposition for trees.
2 Copyright (C) 2003-2021 Free Software Foundation, Inc.
3
4 This file is part of GCC.
5
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.
10
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.
15
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/>. */
19
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"
50
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;
54
55 /* Misc functions used in this file. */
56
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:
60
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!
64
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. */
68
69 /* Add statement T in function IFUN to landing pad NUM. */
70
71 static void
add_stmt_to_eh_lp_fn(struct function * ifun,gimple * t,int num)72 add_stmt_to_eh_lp_fn (struct function *ifun, gimple *t, int num)
73 {
74 gcc_assert (num != 0);
75
76 if (!get_eh_throw_stmt_table (ifun))
77 set_eh_throw_stmt_table (ifun, hash_map<gimple *, int>::create_ggc (31));
78
79 gcc_assert (!get_eh_throw_stmt_table (ifun)->put (t, num));
80 }
81
82 /* Add statement T in the current function (cfun) to EH landing pad NUM. */
83
84 void
add_stmt_to_eh_lp(gimple * t,int num)85 add_stmt_to_eh_lp (gimple *t, int num)
86 {
87 add_stmt_to_eh_lp_fn (cfun, t, num);
88 }
89
90 /* Add statement T to the single EH landing pad in REGION. */
91
92 static void
record_stmt_eh_region(eh_region region,gimple * t)93 record_stmt_eh_region (eh_region region, gimple *t)
94 {
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
100 {
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);
107 }
108 }
109
110
111 /* Remove statement T in function IFUN from its EH landing pad. */
112
113 bool
remove_stmt_from_eh_lp_fn(struct function * ifun,gimple * t)114 remove_stmt_from_eh_lp_fn (struct function *ifun, gimple *t)
115 {
116 if (!get_eh_throw_stmt_table (ifun))
117 return false;
118
119 if (!get_eh_throw_stmt_table (ifun)->get (t))
120 return false;
121
122 get_eh_throw_stmt_table (ifun)->remove (t);
123 return true;
124 }
125
126
127 /* Remove statement T in the current function (cfun) from its
128 EH landing pad. */
129
130 bool
remove_stmt_from_eh_lp(gimple * t)131 remove_stmt_from_eh_lp (gimple *t)
132 {
133 return remove_stmt_from_eh_lp_fn (cfun, t);
134 }
135
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. */
140
141 int
lookup_stmt_eh_lp_fn(struct function * ifun,const gimple * t)142 lookup_stmt_eh_lp_fn (struct function *ifun, const gimple *t)
143 {
144 if (ifun->eh->throw_stmt_table == NULL)
145 return 0;
146
147 int *lp_nr = ifun->eh->throw_stmt_table->get (const_cast <gimple *> (t));
148 return lp_nr ? *lp_nr : 0;
149 }
150
151 /* Likewise, but always use the current function. */
152
153 int
lookup_stmt_eh_lp(const gimple * t)154 lookup_stmt_eh_lp (const gimple *t)
155 {
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);
161 }
162
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. */
166
167 struct finally_tree_node
168 {
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;
175 };
176
177 /* Hashtable helpers. */
178
179 struct finally_tree_hasher : free_ptr_hash <finally_tree_node>
180 {
181 static inline hashval_t hash (const finally_tree_node *);
182 static inline bool equal (const finally_tree_node *,
183 const finally_tree_node *);
184 };
185
186 inline hashval_t
hash(const finally_tree_node * v)187 finally_tree_hasher::hash (const finally_tree_node *v)
188 {
189 return (intptr_t)v->child.t >> 4;
190 }
191
192 inline bool
equal(const finally_tree_node * v,const finally_tree_node * c)193 finally_tree_hasher::equal (const finally_tree_node *v,
194 const finally_tree_node *c)
195 {
196 return v->child.t == c->child.t;
197 }
198
199 /* Note that this table is *not* marked GTY. It is short-lived. */
200 static hash_table<finally_tree_hasher> *finally_tree;
201
202 static void
record_in_finally_tree(treemple child,gtry * parent)203 record_in_finally_tree (treemple child, gtry *parent)
204 {
205 struct finally_tree_node *n;
206 finally_tree_node **slot;
207
208 n = XNEW (struct finally_tree_node);
209 n->child = child;
210 n->parent = parent;
211
212 slot = finally_tree->find_slot (n, INSERT);
213 gcc_assert (!*slot);
214 *slot = n;
215 }
216
217 static void
218 collect_finally_tree (gimple *stmt, gtry *region);
219
220 /* Go through the gimple sequence. Works with collect_finally_tree to
221 record all GIMPLE_LABEL and GIMPLE_TRY statements. */
222
223 static void
collect_finally_tree_1(gimple_seq seq,gtry * region)224 collect_finally_tree_1 (gimple_seq seq, gtry *region)
225 {
226 gimple_stmt_iterator gsi;
227
228 for (gsi = gsi_start (seq); !gsi_end_p (gsi); gsi_next (&gsi))
229 collect_finally_tree (gsi_stmt (gsi), region);
230 }
231
232 static void
collect_finally_tree(gimple * stmt,gtry * region)233 collect_finally_tree (gimple *stmt, gtry *region)
234 {
235 treemple temp;
236
237 switch (gimple_code (stmt))
238 {
239 case GIMPLE_LABEL:
240 temp.t = gimple_label_label (as_a <glabel *> (stmt));
241 record_in_finally_tree (temp, region);
242 break;
243
244 case GIMPLE_TRY:
245 if (gimple_try_kind (stmt) == GIMPLE_TRY_FINALLY)
246 {
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);
252 }
253 else if (gimple_try_kind (stmt) == GIMPLE_TRY_CATCH)
254 {
255 collect_finally_tree_1 (gimple_try_eval (stmt), region);
256 collect_finally_tree_1 (gimple_try_cleanup (stmt), region);
257 }
258 break;
259
260 case GIMPLE_CATCH:
261 collect_finally_tree_1 (gimple_catch_handler (
262 as_a <gcatch *> (stmt)),
263 region);
264 break;
265
266 case GIMPLE_EH_FILTER:
267 collect_finally_tree_1 (gimple_eh_filter_failure (stmt), region);
268 break;
269
270 case GIMPLE_EH_ELSE:
271 {
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);
275 }
276 break;
277
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;
282 }
283 }
284
285
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. */
288
289 static bool
outside_finally_tree(treemple start,gimple * target)290 outside_finally_tree (treemple start, gimple *target)
291 {
292 struct finally_tree_node n, *p;
293
294 do
295 {
296 n.child = start;
297 p = finally_tree->find (&n);
298 if (!p)
299 return true;
300 start.g = p->parent;
301 }
302 while (start.g != target);
303
304 return false;
305 }
306
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. */
311
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;
315
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;
319
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. */
328
329 struct goto_queue_node
330 {
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;
339 };
340
341 /* State of the world while lowering. */
342
343 struct leh_state
344 {
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;
349
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;
354
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;
359
360 /* Outer non-clean up region. */
361 eh_region outer_non_cleanup;
362 };
363
364 struct leh_tf_state
365 {
366 /* Pointer to the GIMPLE_TRY_FINALLY node under discussion. The
367 try_finally_expr is the original GIMPLE_TRY_FINALLY. We need to retain
368 this so that outside_finally_tree can reliably reference the tree used
369 in the collect_finally_tree data structures. */
370 gtry *try_finally_expr;
371 gtry *top_p;
372
373 /* While lowering a top_p usually it is expanded into multiple statements,
374 thus we need the following field to store them. */
375 gimple_seq top_p_seq;
376
377 /* The state outside this try_finally node. */
378 struct leh_state *outer;
379
380 /* The exception region created for it. */
381 eh_region region;
382
383 /* The goto queue. */
384 struct goto_queue_node *goto_queue;
385 size_t goto_queue_size;
386 size_t goto_queue_active;
387
388 /* Pointer map to help in searching goto_queue when it is large. */
389 hash_map<gimple *, goto_queue_node *> *goto_queue_map;
390
391 /* The set of unique labels seen as entries in the goto queue. */
392 vec<tree> dest_array;
393
394 /* A label to be added at the end of the completed transformed
395 sequence. It will be set if may_fallthru was true *at one time*,
396 though subsequent transformations may have cleared that flag. */
397 tree fallthru_label;
398
399 /* True if it is possible to fall out the bottom of the try block.
400 Cleared if the fallthru is converted to a goto. */
401 bool may_fallthru;
402
403 /* True if any entry in goto_queue is a GIMPLE_RETURN. */
404 bool may_return;
405
406 /* True if the finally block can receive an exception edge.
407 Cleared if the exception case is handled by code duplication. */
408 bool may_throw;
409 };
410
411 static gimple_seq lower_eh_must_not_throw (struct leh_state *, gtry *);
412
413 /* Search for STMT in the goto queue. Return the replacement,
414 or null if the statement isn't in the queue. */
415
416 #define LARGE_GOTO_QUEUE 20
417
418 static void lower_eh_constructs_1 (struct leh_state *state, gimple_seq *seq);
419
420 static gimple_seq
find_goto_replacement(struct leh_tf_state * tf,treemple stmt)421 find_goto_replacement (struct leh_tf_state *tf, treemple stmt)
422 {
423 unsigned int i;
424
425 if (tf->goto_queue_active < LARGE_GOTO_QUEUE)
426 {
427 for (i = 0; i < tf->goto_queue_active; i++)
428 if ( tf->goto_queue[i].stmt.g == stmt.g)
429 return tf->goto_queue[i].repl_stmt;
430 return NULL;
431 }
432
433 /* If we have a large number of entries in the goto_queue, create a
434 pointer map and use that for searching. */
435
436 if (!tf->goto_queue_map)
437 {
438 tf->goto_queue_map = new hash_map<gimple *, goto_queue_node *>;
439 for (i = 0; i < tf->goto_queue_active; i++)
440 {
441 bool existed = tf->goto_queue_map->put (tf->goto_queue[i].stmt.g,
442 &tf->goto_queue[i]);
443 gcc_assert (!existed);
444 }
445 }
446
447 goto_queue_node **slot = tf->goto_queue_map->get (stmt.g);
448 if (slot != NULL)
449 return ((*slot)->repl_stmt);
450
451 return NULL;
452 }
453
454 /* A subroutine of replace_goto_queue_1. Handles the sub-clauses of a
455 lowered GIMPLE_COND. If, by chance, the replacement is a simple goto,
456 then we can just splat it in, otherwise we add the new stmts immediately
457 after the GIMPLE_COND and redirect. */
458
459 static void
replace_goto_queue_cond_clause(tree * tp,struct leh_tf_state * tf,gimple_stmt_iterator * gsi)460 replace_goto_queue_cond_clause (tree *tp, struct leh_tf_state *tf,
461 gimple_stmt_iterator *gsi)
462 {
463 tree label;
464 gimple_seq new_seq;
465 treemple temp;
466 location_t loc = gimple_location (gsi_stmt (*gsi));
467
468 temp.tp = tp;
469 new_seq = find_goto_replacement (tf, temp);
470 if (!new_seq)
471 return;
472
473 if (gimple_seq_singleton_p (new_seq)
474 && gimple_code (gimple_seq_first_stmt (new_seq)) == GIMPLE_GOTO)
475 {
476 *tp = gimple_goto_dest (gimple_seq_first_stmt (new_seq));
477 return;
478 }
479
480 label = create_artificial_label (loc);
481 /* Set the new label for the GIMPLE_COND */
482 *tp = label;
483
484 gsi_insert_after (gsi, gimple_build_label (label), GSI_CONTINUE_LINKING);
485 gsi_insert_seq_after (gsi, gimple_seq_copy (new_seq), GSI_CONTINUE_LINKING);
486 }
487
488 /* The real work of replace_goto_queue. Returns with TSI updated to
489 point to the next statement. */
490
491 static void replace_goto_queue_stmt_list (gimple_seq *, struct leh_tf_state *);
492
493 static void
replace_goto_queue_1(gimple * stmt,struct leh_tf_state * tf,gimple_stmt_iterator * gsi)494 replace_goto_queue_1 (gimple *stmt, struct leh_tf_state *tf,
495 gimple_stmt_iterator *gsi)
496 {
497 gimple_seq seq;
498 treemple temp;
499 temp.g = NULL;
500
501 switch (gimple_code (stmt))
502 {
503 case GIMPLE_GOTO:
504 case GIMPLE_RETURN:
505 temp.g = stmt;
506 seq = find_goto_replacement (tf, temp);
507 if (seq)
508 {
509 gimple_stmt_iterator i;
510 seq = gimple_seq_copy (seq);
511 for (i = gsi_start (seq); !gsi_end_p (i); gsi_next (&i))
512 gimple_set_location (gsi_stmt (i), gimple_location (stmt));
513 gsi_insert_seq_before (gsi, seq, GSI_SAME_STMT);
514 gsi_remove (gsi, false);
515 return;
516 }
517 break;
518
519 case GIMPLE_COND:
520 replace_goto_queue_cond_clause (gimple_op_ptr (stmt, 2), tf, gsi);
521 replace_goto_queue_cond_clause (gimple_op_ptr (stmt, 3), tf, gsi);
522 break;
523
524 case GIMPLE_TRY:
525 replace_goto_queue_stmt_list (gimple_try_eval_ptr (stmt), tf);
526 replace_goto_queue_stmt_list (gimple_try_cleanup_ptr (stmt), tf);
527 break;
528 case GIMPLE_CATCH:
529 replace_goto_queue_stmt_list (gimple_catch_handler_ptr (
530 as_a <gcatch *> (stmt)),
531 tf);
532 break;
533 case GIMPLE_EH_FILTER:
534 replace_goto_queue_stmt_list (gimple_eh_filter_failure_ptr (stmt), tf);
535 break;
536 case GIMPLE_EH_ELSE:
537 {
538 geh_else *eh_else_stmt = as_a <geh_else *> (stmt);
539 replace_goto_queue_stmt_list (gimple_eh_else_n_body_ptr (eh_else_stmt),
540 tf);
541 replace_goto_queue_stmt_list (gimple_eh_else_e_body_ptr (eh_else_stmt),
542 tf);
543 }
544 break;
545
546 default:
547 /* These won't have gotos in them. */
548 break;
549 }
550
551 gsi_next (gsi);
552 }
553
554 /* A subroutine of replace_goto_queue. Handles GIMPLE_SEQ. */
555
556 static void
replace_goto_queue_stmt_list(gimple_seq * seq,struct leh_tf_state * tf)557 replace_goto_queue_stmt_list (gimple_seq *seq, struct leh_tf_state *tf)
558 {
559 gimple_stmt_iterator gsi = gsi_start (*seq);
560
561 while (!gsi_end_p (gsi))
562 replace_goto_queue_1 (gsi_stmt (gsi), tf, &gsi);
563 }
564
565 /* Replace all goto queue members. */
566
567 static void
replace_goto_queue(struct leh_tf_state * tf)568 replace_goto_queue (struct leh_tf_state *tf)
569 {
570 if (tf->goto_queue_active == 0)
571 return;
572 replace_goto_queue_stmt_list (&tf->top_p_seq, tf);
573 replace_goto_queue_stmt_list (&eh_seq, tf);
574 }
575
576 /* Add a new record to the goto queue contained in TF. NEW_STMT is the
577 data to be added, IS_LABEL indicates whether NEW_STMT is a label or
578 a gimple return. */
579
580 static void
record_in_goto_queue(struct leh_tf_state * tf,treemple new_stmt,int index,bool is_label,location_t location)581 record_in_goto_queue (struct leh_tf_state *tf,
582 treemple new_stmt,
583 int index,
584 bool is_label,
585 location_t location)
586 {
587 size_t active, size;
588 struct goto_queue_node *q;
589
590 gcc_assert (!tf->goto_queue_map);
591
592 active = tf->goto_queue_active;
593 size = tf->goto_queue_size;
594 if (active >= size)
595 {
596 size = (size ? size * 2 : 32);
597 tf->goto_queue_size = size;
598 tf->goto_queue
599 = XRESIZEVEC (struct goto_queue_node, tf->goto_queue, size);
600 }
601
602 q = &tf->goto_queue[active];
603 tf->goto_queue_active = active + 1;
604
605 memset (q, 0, sizeof (*q));
606 q->stmt = new_stmt;
607 q->index = index;
608 q->location = location;
609 q->is_label = is_label;
610 }
611
612 /* Record the LABEL label in the goto queue contained in TF.
613 TF is not null. */
614
615 static void
record_in_goto_queue_label(struct leh_tf_state * tf,treemple stmt,tree label,location_t location)616 record_in_goto_queue_label (struct leh_tf_state *tf, treemple stmt, tree label,
617 location_t location)
618 {
619 int index;
620 treemple temp, new_stmt;
621
622 if (!label)
623 return;
624
625 /* Computed and non-local gotos do not get processed. Given
626 their nature we can neither tell whether we've escaped the
627 finally block nor redirect them if we knew. */
628 if (TREE_CODE (label) != LABEL_DECL)
629 return;
630
631 /* No need to record gotos that don't leave the try block. */
632 temp.t = label;
633 if (!outside_finally_tree (temp, tf->try_finally_expr))
634 return;
635
636 if (! tf->dest_array.exists ())
637 {
638 tf->dest_array.create (10);
639 tf->dest_array.quick_push (label);
640 index = 0;
641 }
642 else
643 {
644 int n = tf->dest_array.length ();
645 for (index = 0; index < n; ++index)
646 if (tf->dest_array[index] == label)
647 break;
648 if (index == n)
649 tf->dest_array.safe_push (label);
650 }
651
652 /* In the case of a GOTO we want to record the destination label,
653 since with a GIMPLE_COND we have an easy access to the then/else
654 labels. */
655 new_stmt = stmt;
656 record_in_goto_queue (tf, new_stmt, index, true, location);
657 }
658
659 /* For any GIMPLE_GOTO or GIMPLE_RETURN, decide whether it leaves a try_finally
660 node, and if so record that fact in the goto queue associated with that
661 try_finally node. */
662
663 static void
maybe_record_in_goto_queue(struct leh_state * state,gimple * stmt)664 maybe_record_in_goto_queue (struct leh_state *state, gimple *stmt)
665 {
666 struct leh_tf_state *tf = state->tf;
667 treemple new_stmt;
668
669 if (!tf)
670 return;
671
672 switch (gimple_code (stmt))
673 {
674 case GIMPLE_COND:
675 {
676 gcond *cond_stmt = as_a <gcond *> (stmt);
677 new_stmt.tp = gimple_op_ptr (cond_stmt, 2);
678 record_in_goto_queue_label (tf, new_stmt,
679 gimple_cond_true_label (cond_stmt),
680 EXPR_LOCATION (*new_stmt.tp));
681 new_stmt.tp = gimple_op_ptr (cond_stmt, 3);
682 record_in_goto_queue_label (tf, new_stmt,
683 gimple_cond_false_label (cond_stmt),
684 EXPR_LOCATION (*new_stmt.tp));
685 }
686 break;
687 case GIMPLE_GOTO:
688 new_stmt.g = stmt;
689 record_in_goto_queue_label (tf, new_stmt, gimple_goto_dest (stmt),
690 gimple_location (stmt));
691 break;
692
693 case GIMPLE_RETURN:
694 tf->may_return = true;
695 new_stmt.g = stmt;
696 record_in_goto_queue (tf, new_stmt, -1, false, gimple_location (stmt));
697 break;
698
699 default:
700 gcc_unreachable ();
701 }
702 }
703
704
705 #if CHECKING_P
706 /* We do not process GIMPLE_SWITCHes for now. As long as the original source
707 was in fact structured, and we've not yet done jump threading, then none
708 of the labels will leave outer GIMPLE_TRY_FINALLY nodes. Verify this. */
709
710 static void
verify_norecord_switch_expr(struct leh_state * state,gswitch * switch_expr)711 verify_norecord_switch_expr (struct leh_state *state,
712 gswitch *switch_expr)
713 {
714 struct leh_tf_state *tf = state->tf;
715 size_t i, n;
716
717 if (!tf)
718 return;
719
720 n = gimple_switch_num_labels (switch_expr);
721
722 for (i = 0; i < n; ++i)
723 {
724 treemple temp;
725 tree lab = CASE_LABEL (gimple_switch_label (switch_expr, i));
726 temp.t = lab;
727 gcc_assert (!outside_finally_tree (temp, tf->try_finally_expr));
728 }
729 }
730 #else
731 #define verify_norecord_switch_expr(state, switch_expr)
732 #endif
733
734 /* Redirect a RETURN_EXPR pointed to by Q to FINLAB. If MOD is
735 non-null, insert it before the new branch. */
736
737 static void
do_return_redirection(struct goto_queue_node * q,tree finlab,gimple_seq mod)738 do_return_redirection (struct goto_queue_node *q, tree finlab, gimple_seq mod)
739 {
740 gimple *x;
741
742 /* In the case of a return, the queue node must be a gimple statement. */
743 gcc_assert (!q->is_label);
744
745 /* Note that the return value may have already been computed, e.g.,
746
747 int x;
748 int foo (void)
749 {
750 x = 0;
751 try {
752 return x;
753 } finally {
754 x++;
755 }
756 }
757
758 should return 0, not 1. We don't have to do anything to make
759 this happens because the return value has been placed in the
760 RESULT_DECL already. */
761
762 q->cont_stmt = q->stmt.g;
763
764 if (mod)
765 gimple_seq_add_seq (&q->repl_stmt, mod);
766
767 x = gimple_build_goto (finlab);
768 gimple_set_location (x, q->location);
769 gimple_seq_add_stmt (&q->repl_stmt, x);
770 }
771
772 /* Similar, but easier, for GIMPLE_GOTO. */
773
774 static void
do_goto_redirection(struct goto_queue_node * q,tree finlab,gimple_seq mod,struct leh_tf_state * tf)775 do_goto_redirection (struct goto_queue_node *q, tree finlab, gimple_seq mod,
776 struct leh_tf_state *tf)
777 {
778 ggoto *x;
779
780 gcc_assert (q->is_label);
781
782 q->cont_stmt = gimple_build_goto (tf->dest_array[q->index]);
783
784 if (mod)
785 gimple_seq_add_seq (&q->repl_stmt, mod);
786
787 x = gimple_build_goto (finlab);
788 gimple_set_location (x, q->location);
789 gimple_seq_add_stmt (&q->repl_stmt, x);
790 }
791
792 /* Emit a standard landing pad sequence into SEQ for REGION. */
793
794 static void
emit_post_landing_pad(gimple_seq * seq,eh_region region)795 emit_post_landing_pad (gimple_seq *seq, eh_region region)
796 {
797 eh_landing_pad lp = region->landing_pads;
798 glabel *x;
799
800 if (lp == NULL)
801 lp = gen_eh_landing_pad (region);
802
803 lp->post_landing_pad = create_artificial_label (UNKNOWN_LOCATION);
804 EH_LANDING_PAD_NR (lp->post_landing_pad) = lp->index;
805
806 x = gimple_build_label (lp->post_landing_pad);
807 gimple_seq_add_stmt (seq, x);
808 }
809
810 /* Emit a RESX statement into SEQ for REGION. */
811
812 static void
emit_resx(gimple_seq * seq,eh_region region)813 emit_resx (gimple_seq *seq, eh_region region)
814 {
815 gresx *x = gimple_build_resx (region->index);
816 gimple_seq_add_stmt (seq, x);
817 if (region->outer)
818 record_stmt_eh_region (region->outer, x);
819 }
820
821 /* Note that the current EH region may contain a throw, or a
822 call to a function which itself may contain a throw. */
823
824 static void
note_eh_region_may_contain_throw(eh_region region)825 note_eh_region_may_contain_throw (eh_region region)
826 {
827 while (bitmap_set_bit (eh_region_may_contain_throw_map, region->index))
828 {
829 if (region->type == ERT_MUST_NOT_THROW)
830 break;
831 region = region->outer;
832 if (region == NULL)
833 break;
834 }
835 }
836
837 /* Check if REGION has been marked as containing a throw. If REGION is
838 NULL, this predicate is false. */
839
840 static inline bool
eh_region_may_contain_throw(eh_region r)841 eh_region_may_contain_throw (eh_region r)
842 {
843 return r && bitmap_bit_p (eh_region_may_contain_throw_map, r->index);
844 }
845
846 /* We want to transform
847 try { body; } catch { stuff; }
848 to
849 normal_sequence:
850 body;
851 over:
852 eh_sequence:
853 landing_pad:
854 stuff;
855 goto over;
856
857 TP is a GIMPLE_TRY node. REGION is the region whose post_landing_pad
858 should be placed before the second operand, or NULL. OVER is
859 an existing label that should be put at the exit, or NULL. */
860
861 static gimple_seq
frob_into_branch_around(gtry * tp,eh_region region,tree over)862 frob_into_branch_around (gtry *tp, eh_region region, tree over)
863 {
864 gimple *x;
865 gimple_seq cleanup, result;
866 location_t loc = gimple_location (tp);
867
868 cleanup = gimple_try_cleanup (tp);
869 result = gimple_try_eval (tp);
870
871 if (region)
872 emit_post_landing_pad (&eh_seq, region);
873
874 if (gimple_seq_may_fallthru (cleanup))
875 {
876 if (!over)
877 over = create_artificial_label (loc);
878 x = gimple_build_goto (over);
879 gimple_set_location (x, loc);
880 gimple_seq_add_stmt (&cleanup, x);
881 }
882 gimple_seq_add_seq (&eh_seq, cleanup);
883
884 if (over)
885 {
886 x = gimple_build_label (over);
887 gimple_seq_add_stmt (&result, x);
888 }
889 return result;
890 }
891
892 /* A subroutine of lower_try_finally. Duplicate the tree rooted at T.
893 Make sure to record all new labels found. */
894
895 static gimple_seq
lower_try_finally_dup_block(gimple_seq seq,struct leh_state * outer_state,location_t loc)896 lower_try_finally_dup_block (gimple_seq seq, struct leh_state *outer_state,
897 location_t loc)
898 {
899 gtry *region = NULL;
900 gimple_seq new_seq;
901 gimple_stmt_iterator gsi;
902
903 new_seq = copy_gimple_seq_and_replace_locals (seq);
904
905 for (gsi = gsi_start (new_seq); !gsi_end_p (gsi); gsi_next (&gsi))
906 {
907 gimple *stmt = gsi_stmt (gsi);
908 if (LOCATION_LOCUS (gimple_location (stmt)) == UNKNOWN_LOCATION)
909 {
910 tree block = gimple_block (stmt);
911 gimple_set_location (stmt, loc);
912 gimple_set_block (stmt, block);
913 }
914 }
915
916 if (outer_state->tf)
917 region = outer_state->tf->try_finally_expr;
918 collect_finally_tree_1 (new_seq, region);
919
920 return new_seq;
921 }
922
923 /* A subroutine of lower_try_finally. Create a fallthru label for
924 the given try_finally state. The only tricky bit here is that
925 we have to make sure to record the label in our outer context. */
926
927 static tree
lower_try_finally_fallthru_label(struct leh_tf_state * tf)928 lower_try_finally_fallthru_label (struct leh_tf_state *tf)
929 {
930 tree label = tf->fallthru_label;
931 treemple temp;
932
933 if (!label)
934 {
935 label = create_artificial_label (gimple_location (tf->try_finally_expr));
936 tf->fallthru_label = label;
937 if (tf->outer->tf)
938 {
939 temp.t = label;
940 record_in_finally_tree (temp, tf->outer->tf->try_finally_expr);
941 }
942 }
943 return label;
944 }
945
946 /* A subroutine of lower_try_finally. If FINALLY consits of a
947 GIMPLE_EH_ELSE node, return it. */
948
949 static inline geh_else *
get_eh_else(gimple_seq finally)950 get_eh_else (gimple_seq finally)
951 {
952 gimple *x = gimple_seq_first_stmt (finally);
953 if (gimple_code (x) == GIMPLE_EH_ELSE)
954 {
955 gcc_assert (gimple_seq_singleton_p (finally));
956 return as_a <geh_else *> (x);
957 }
958 return NULL;
959 }
960
961 /* A subroutine of lower_try_finally. If the eh_protect_cleanup_actions
962 langhook returns non-null, then the language requires that the exception
963 path out of a try_finally be treated specially. To wit: the code within
964 the finally block may not itself throw an exception. We have two choices
965 here. First we can duplicate the finally block and wrap it in a
966 must_not_throw region. Second, we can generate code like
967
968 try {
969 finally_block;
970 } catch {
971 if (fintmp == eh_edge)
972 protect_cleanup_actions;
973 }
974
975 where "fintmp" is the temporary used in the switch statement generation
976 alternative considered below. For the nonce, we always choose the first
977 option.
978
979 THIS_STATE may be null if this is a try-cleanup, not a try-finally. */
980
981 static void
honor_protect_cleanup_actions(struct leh_state * outer_state,struct leh_state * this_state,struct leh_tf_state * tf)982 honor_protect_cleanup_actions (struct leh_state *outer_state,
983 struct leh_state *this_state,
984 struct leh_tf_state *tf)
985 {
986 gimple_seq finally = gimple_try_cleanup (tf->top_p);
987
988 /* EH_ELSE doesn't come from user code; only compiler generated stuff.
989 It does need to be handled here, so as to separate the (different)
990 EH path from the normal path. But we should not attempt to wrap
991 it with a must-not-throw node (which indeed gets in the way). */
992 if (geh_else *eh_else = get_eh_else (finally))
993 {
994 gimple_try_set_cleanup (tf->top_p, gimple_eh_else_n_body (eh_else));
995 finally = gimple_eh_else_e_body (eh_else);
996
997 /* Let the ELSE see the exception that's being processed, but
998 since the cleanup is outside the try block, process it with
999 outer_state, otherwise it may be used as a cleanup for
1000 itself, and Bad Things (TM) ensue. */
1001 eh_region save_ehp = outer_state->ehp_region;
1002 outer_state->ehp_region = this_state->cur_region;
1003 lower_eh_constructs_1 (outer_state, &finally);
1004 outer_state->ehp_region = save_ehp;
1005 }
1006 else
1007 {
1008 /* First check for nothing to do. */
1009 if (lang_hooks.eh_protect_cleanup_actions == NULL)
1010 return;
1011 tree actions = lang_hooks.eh_protect_cleanup_actions ();
1012 if (actions == NULL)
1013 return;
1014
1015 if (this_state)
1016 finally = lower_try_finally_dup_block (finally, outer_state,
1017 gimple_location (tf->try_finally_expr));
1018
1019 /* If this cleanup consists of a TRY_CATCH_EXPR with TRY_CATCH_IS_CLEANUP
1020 set, the handler of the TRY_CATCH_EXPR is another cleanup which ought
1021 to be in an enclosing scope, but needs to be implemented at this level
1022 to avoid a nesting violation (see wrap_temporary_cleanups in
1023 cp/decl.c). Since it's logically at an outer level, we should call
1024 terminate before we get to it, so strip it away before adding the
1025 MUST_NOT_THROW filter. */
1026 gimple_stmt_iterator gsi = gsi_start (finally);
1027 gimple *x = gsi_stmt (gsi);
1028 if (gimple_code (x) == GIMPLE_TRY
1029 && gimple_try_kind (x) == GIMPLE_TRY_CATCH
1030 && gimple_try_catch_is_cleanup (x))
1031 {
1032 gsi_insert_seq_before (&gsi, gimple_try_eval (x), GSI_SAME_STMT);
1033 gsi_remove (&gsi, false);
1034 }
1035
1036 /* Wrap the block with protect_cleanup_actions as the action. */
1037 geh_mnt *eh_mnt = gimple_build_eh_must_not_throw (actions);
1038 gtry *try_stmt = gimple_build_try (finally,
1039 gimple_seq_alloc_with_stmt (eh_mnt),
1040 GIMPLE_TRY_CATCH);
1041 finally = lower_eh_must_not_throw (outer_state, try_stmt);
1042 }
1043
1044 /* Drop all of this into the exception sequence. */
1045 emit_post_landing_pad (&eh_seq, tf->region);
1046 gimple_seq_add_seq (&eh_seq, finally);
1047 if (gimple_seq_may_fallthru (finally))
1048 emit_resx (&eh_seq, tf->region);
1049
1050 /* Having now been handled, EH isn't to be considered with
1051 the rest of the outgoing edges. */
1052 tf->may_throw = false;
1053 }
1054
1055 /* A subroutine of lower_try_finally. We have determined that there is
1056 no fallthru edge out of the finally block. This means that there is
1057 no outgoing edge corresponding to any incoming edge. Restructure the
1058 try_finally node for this special case. */
1059
1060 static void
lower_try_finally_nofallthru(struct leh_state * state,struct leh_tf_state * tf)1061 lower_try_finally_nofallthru (struct leh_state *state,
1062 struct leh_tf_state *tf)
1063 {
1064 tree lab;
1065 gimple *x;
1066 geh_else *eh_else;
1067 gimple_seq finally;
1068 struct goto_queue_node *q, *qe;
1069
1070 lab = create_artificial_label (gimple_location (tf->try_finally_expr));
1071
1072 /* We expect that tf->top_p is a GIMPLE_TRY. */
1073 finally = gimple_try_cleanup (tf->top_p);
1074 tf->top_p_seq = gimple_try_eval (tf->top_p);
1075
1076 x = gimple_build_label (lab);
1077 gimple_seq_add_stmt (&tf->top_p_seq, x);
1078
1079 q = tf->goto_queue;
1080 qe = q + tf->goto_queue_active;
1081 for (; q < qe; ++q)
1082 if (q->index < 0)
1083 do_return_redirection (q, lab, NULL);
1084 else
1085 do_goto_redirection (q, lab, NULL, tf);
1086
1087 replace_goto_queue (tf);
1088
1089 /* Emit the finally block into the stream. Lower EH_ELSE at this time. */
1090 eh_else = get_eh_else (finally);
1091 if (eh_else)
1092 {
1093 finally = gimple_eh_else_n_body (eh_else);
1094 lower_eh_constructs_1 (state, &finally);
1095 gimple_seq_add_seq (&tf->top_p_seq, finally);
1096
1097 if (tf->may_throw)
1098 {
1099 finally = gimple_eh_else_e_body (eh_else);
1100 lower_eh_constructs_1 (state, &finally);
1101
1102 emit_post_landing_pad (&eh_seq, tf->region);
1103 gimple_seq_add_seq (&eh_seq, finally);
1104 }
1105 }
1106 else
1107 {
1108 lower_eh_constructs_1 (state, &finally);
1109 gimple_seq_add_seq (&tf->top_p_seq, finally);
1110
1111 if (tf->may_throw)
1112 {
1113 emit_post_landing_pad (&eh_seq, tf->region);
1114
1115 x = gimple_build_goto (lab);
1116 gimple_set_location (x, gimple_location (tf->try_finally_expr));
1117 gimple_seq_add_stmt (&eh_seq, x);
1118 }
1119 }
1120 }
1121
1122 /* A subroutine of lower_try_finally. We have determined that there is
1123 exactly one destination of the finally block. Restructure the
1124 try_finally node for this special case. */
1125
1126 static void
lower_try_finally_onedest(struct leh_state * state,struct leh_tf_state * tf)1127 lower_try_finally_onedest (struct leh_state *state, struct leh_tf_state *tf)
1128 {
1129 struct goto_queue_node *q, *qe;
1130 geh_else *eh_else;
1131 glabel *label_stmt;
1132 gimple *x;
1133 gimple_seq finally;
1134 gimple_stmt_iterator gsi;
1135 tree finally_label;
1136 location_t loc = gimple_location (tf->try_finally_expr);
1137
1138 finally = gimple_try_cleanup (tf->top_p);
1139 tf->top_p_seq = gimple_try_eval (tf->top_p);
1140
1141 /* Since there's only one destination, and the destination edge can only
1142 either be EH or non-EH, that implies that all of our incoming edges
1143 are of the same type. Therefore we can lower EH_ELSE immediately. */
1144 eh_else = get_eh_else (finally);
1145 if (eh_else)
1146 {
1147 if (tf->may_throw)
1148 finally = gimple_eh_else_e_body (eh_else);
1149 else
1150 finally = gimple_eh_else_n_body (eh_else);
1151 }
1152
1153 lower_eh_constructs_1 (state, &finally);
1154
1155 for (gsi = gsi_start (finally); !gsi_end_p (gsi); gsi_next (&gsi))
1156 {
1157 gimple *stmt = gsi_stmt (gsi);
1158 if (LOCATION_LOCUS (gimple_location (stmt)) == UNKNOWN_LOCATION)
1159 {
1160 tree block = gimple_block (stmt);
1161 gimple_set_location (stmt, gimple_location (tf->try_finally_expr));
1162 gimple_set_block (stmt, block);
1163 }
1164 }
1165
1166 if (tf->may_throw)
1167 {
1168 /* Only reachable via the exception edge. Add the given label to
1169 the head of the FINALLY block. Append a RESX at the end. */
1170 emit_post_landing_pad (&eh_seq, tf->region);
1171 gimple_seq_add_seq (&eh_seq, finally);
1172 emit_resx (&eh_seq, tf->region);
1173 return;
1174 }
1175
1176 if (tf->may_fallthru)
1177 {
1178 /* Only reachable via the fallthru edge. Do nothing but let
1179 the two blocks run together; we'll fall out the bottom. */
1180 gimple_seq_add_seq (&tf->top_p_seq, finally);
1181 return;
1182 }
1183
1184 finally_label = create_artificial_label (loc);
1185 label_stmt = gimple_build_label (finally_label);
1186 gimple_seq_add_stmt (&tf->top_p_seq, label_stmt);
1187
1188 gimple_seq_add_seq (&tf->top_p_seq, finally);
1189
1190 q = tf->goto_queue;
1191 qe = q + tf->goto_queue_active;
1192
1193 if (tf->may_return)
1194 {
1195 /* Reachable by return expressions only. Redirect them. */
1196 for (; q < qe; ++q)
1197 do_return_redirection (q, finally_label, NULL);
1198 replace_goto_queue (tf);
1199 }
1200 else
1201 {
1202 /* Reachable by goto expressions only. Redirect them. */
1203 for (; q < qe; ++q)
1204 do_goto_redirection (q, finally_label, NULL, tf);
1205 replace_goto_queue (tf);
1206
1207 if (tf->dest_array[0] == tf->fallthru_label)
1208 {
1209 /* Reachable by goto to fallthru label only. Redirect it
1210 to the new label (already created, sadly), and do not
1211 emit the final branch out, or the fallthru label. */
1212 tf->fallthru_label = NULL;
1213 return;
1214 }
1215 }
1216
1217 /* Place the original return/goto to the original destination
1218 immediately after the finally block. */
1219 x = tf->goto_queue[0].cont_stmt;
1220 gimple_seq_add_stmt (&tf->top_p_seq, x);
1221 maybe_record_in_goto_queue (state, x);
1222 }
1223
1224 /* A subroutine of lower_try_finally. There are multiple edges incoming
1225 and outgoing from the finally block. Implement this by duplicating the
1226 finally block for every destination. */
1227
1228 static void
lower_try_finally_copy(struct leh_state * state,struct leh_tf_state * tf)1229 lower_try_finally_copy (struct leh_state *state, struct leh_tf_state *tf)
1230 {
1231 gimple_seq finally;
1232 gimple_seq new_stmt;
1233 gimple_seq seq;
1234 gimple *x;
1235 geh_else *eh_else;
1236 tree tmp;
1237 location_t tf_loc = gimple_location (tf->try_finally_expr);
1238
1239 finally = gimple_try_cleanup (tf->top_p);
1240
1241 /* Notice EH_ELSE, and simplify some of the remaining code
1242 by considering FINALLY to be the normal return path only. */
1243 eh_else = get_eh_else (finally);
1244 if (eh_else)
1245 finally = gimple_eh_else_n_body (eh_else);
1246
1247 tf->top_p_seq = gimple_try_eval (tf->top_p);
1248 new_stmt = NULL;
1249
1250 if (tf->may_fallthru)
1251 {
1252 seq = lower_try_finally_dup_block (finally, state, tf_loc);
1253 lower_eh_constructs_1 (state, &seq);
1254 gimple_seq_add_seq (&new_stmt, seq);
1255
1256 tmp = lower_try_finally_fallthru_label (tf);
1257 x = gimple_build_goto (tmp);
1258 gimple_set_location (x, tf_loc);
1259 gimple_seq_add_stmt (&new_stmt, x);
1260 }
1261
1262 if (tf->may_throw)
1263 {
1264 /* We don't need to copy the EH path of EH_ELSE,
1265 since it is only emitted once. */
1266 if (eh_else)
1267 seq = gimple_eh_else_e_body (eh_else);
1268 else
1269 seq = lower_try_finally_dup_block (finally, state, tf_loc);
1270 lower_eh_constructs_1 (state, &seq);
1271
1272 emit_post_landing_pad (&eh_seq, tf->region);
1273 gimple_seq_add_seq (&eh_seq, seq);
1274 emit_resx (&eh_seq, tf->region);
1275 }
1276
1277 if (tf->goto_queue)
1278 {
1279 struct goto_queue_node *q, *qe;
1280 int return_index, index;
1281 struct labels_s
1282 {
1283 struct goto_queue_node *q;
1284 tree label;
1285 } *labels;
1286
1287 return_index = tf->dest_array.length ();
1288 labels = XCNEWVEC (struct labels_s, return_index + 1);
1289
1290 q = tf->goto_queue;
1291 qe = q + tf->goto_queue_active;
1292 for (; q < qe; q++)
1293 {
1294 index = q->index < 0 ? return_index : q->index;
1295
1296 if (!labels[index].q)
1297 labels[index].q = q;
1298 }
1299
1300 for (index = 0; index < return_index + 1; index++)
1301 {
1302 tree lab;
1303
1304 q = labels[index].q;
1305 if (! q)
1306 continue;
1307
1308 lab = labels[index].label
1309 = create_artificial_label (tf_loc);
1310
1311 if (index == return_index)
1312 do_return_redirection (q, lab, NULL);
1313 else
1314 do_goto_redirection (q, lab, NULL, tf);
1315
1316 x = gimple_build_label (lab);
1317 gimple_seq_add_stmt (&new_stmt, x);
1318
1319 seq = lower_try_finally_dup_block (finally, state, q->location);
1320 lower_eh_constructs_1 (state, &seq);
1321 gimple_seq_add_seq (&new_stmt, seq);
1322
1323 gimple_seq_add_stmt (&new_stmt, q->cont_stmt);
1324 maybe_record_in_goto_queue (state, q->cont_stmt);
1325 }
1326
1327 for (q = tf->goto_queue; q < qe; q++)
1328 {
1329 tree lab;
1330
1331 index = q->index < 0 ? return_index : q->index;
1332
1333 if (labels[index].q == q)
1334 continue;
1335
1336 lab = labels[index].label;
1337
1338 if (index == return_index)
1339 do_return_redirection (q, lab, NULL);
1340 else
1341 do_goto_redirection (q, lab, NULL, tf);
1342 }
1343
1344 replace_goto_queue (tf);
1345 free (labels);
1346 }
1347
1348 /* Need to link new stmts after running replace_goto_queue due
1349 to not wanting to process the same goto stmts twice. */
1350 gimple_seq_add_seq (&tf->top_p_seq, new_stmt);
1351 }
1352
1353 /* A subroutine of lower_try_finally. There are multiple edges incoming
1354 and outgoing from the finally block. Implement this by instrumenting
1355 each incoming edge and creating a switch statement at the end of the
1356 finally block that branches to the appropriate destination. */
1357
1358 static void
lower_try_finally_switch(struct leh_state * state,struct leh_tf_state * tf)1359 lower_try_finally_switch (struct leh_state *state, struct leh_tf_state *tf)
1360 {
1361 struct goto_queue_node *q, *qe;
1362 tree finally_tmp, finally_label;
1363 int return_index, eh_index, fallthru_index;
1364 int nlabels, ndests, j, last_case_index;
1365 tree last_case;
1366 auto_vec<tree> case_label_vec;
1367 gimple_seq switch_body = NULL;
1368 gimple *x;
1369 geh_else *eh_else;
1370 tree tmp;
1371 gimple *switch_stmt;
1372 gimple_seq finally;
1373 hash_map<tree, gimple *> *cont_map = NULL;
1374 /* The location of the TRY_FINALLY stmt. */
1375 location_t tf_loc = gimple_location (tf->try_finally_expr);
1376 /* The location of the finally block. */
1377 location_t finally_loc;
1378
1379 finally = gimple_try_cleanup (tf->top_p);
1380 eh_else = get_eh_else (finally);
1381
1382 /* Mash the TRY block to the head of the chain. */
1383 tf->top_p_seq = gimple_try_eval (tf->top_p);
1384
1385 /* The location of the finally is either the last stmt in the finally
1386 block or the location of the TRY_FINALLY itself. */
1387 x = gimple_seq_last_stmt (finally);
1388 finally_loc = x ? gimple_location (x) : tf_loc;
1389
1390 /* Prepare for switch statement generation. */
1391 nlabels = tf->dest_array.length ();
1392 return_index = nlabels;
1393 eh_index = return_index + tf->may_return;
1394 fallthru_index = eh_index + (tf->may_throw && !eh_else);
1395 ndests = fallthru_index + tf->may_fallthru;
1396
1397 finally_tmp = create_tmp_var (integer_type_node, "finally_tmp");
1398 finally_label = create_artificial_label (finally_loc);
1399
1400 /* We use vec::quick_push on case_label_vec throughout this function,
1401 since we know the size in advance and allocate precisely as muce
1402 space as needed. */
1403 case_label_vec.create (ndests);
1404 last_case = NULL;
1405 last_case_index = 0;
1406
1407 /* Begin inserting code for getting to the finally block. Things
1408 are done in this order to correspond to the sequence the code is
1409 laid out. */
1410
1411 if (tf->may_fallthru)
1412 {
1413 x = gimple_build_assign (finally_tmp,
1414 build_int_cst (integer_type_node,
1415 fallthru_index));
1416 gimple_set_location (x, finally_loc);
1417 gimple_seq_add_stmt (&tf->top_p_seq, x);
1418
1419 tmp = build_int_cst (integer_type_node, fallthru_index);
1420 last_case = build_case_label (tmp, NULL,
1421 create_artificial_label (finally_loc));
1422 case_label_vec.quick_push (last_case);
1423 last_case_index++;
1424
1425 x = gimple_build_label (CASE_LABEL (last_case));
1426 gimple_seq_add_stmt (&switch_body, x);
1427
1428 tmp = lower_try_finally_fallthru_label (tf);
1429 x = gimple_build_goto (tmp);
1430 gimple_set_location (x, finally_loc);
1431 gimple_seq_add_stmt (&switch_body, x);
1432 }
1433
1434 /* For EH_ELSE, emit the exception path (plus resx) now, then
1435 subsequently we only need consider the normal path. */
1436 if (eh_else)
1437 {
1438 if (tf->may_throw)
1439 {
1440 finally = gimple_eh_else_e_body (eh_else);
1441 lower_eh_constructs_1 (state, &finally);
1442
1443 emit_post_landing_pad (&eh_seq, tf->region);
1444 gimple_seq_add_seq (&eh_seq, finally);
1445 emit_resx (&eh_seq, tf->region);
1446 }
1447
1448 finally = gimple_eh_else_n_body (eh_else);
1449 }
1450 else if (tf->may_throw)
1451 {
1452 emit_post_landing_pad (&eh_seq, tf->region);
1453
1454 x = gimple_build_assign (finally_tmp,
1455 build_int_cst (integer_type_node, eh_index));
1456 gimple_seq_add_stmt (&eh_seq, x);
1457
1458 x = gimple_build_goto (finally_label);
1459 gimple_set_location (x, tf_loc);
1460 gimple_seq_add_stmt (&eh_seq, x);
1461
1462 tmp = build_int_cst (integer_type_node, eh_index);
1463 last_case = build_case_label (tmp, NULL,
1464 create_artificial_label (tf_loc));
1465 case_label_vec.quick_push (last_case);
1466 last_case_index++;
1467
1468 x = gimple_build_label (CASE_LABEL (last_case));
1469 gimple_seq_add_stmt (&eh_seq, x);
1470 emit_resx (&eh_seq, tf->region);
1471 }
1472
1473 x = gimple_build_label (finally_label);
1474 gimple_seq_add_stmt (&tf->top_p_seq, x);
1475
1476 lower_eh_constructs_1 (state, &finally);
1477 gimple_seq_add_seq (&tf->top_p_seq, finally);
1478
1479 /* Redirect each incoming goto edge. */
1480 q = tf->goto_queue;
1481 qe = q + tf->goto_queue_active;
1482 j = last_case_index + tf->may_return;
1483 /* Prepare the assignments to finally_tmp that are executed upon the
1484 entrance through a particular edge. */
1485 for (; q < qe; ++q)
1486 {
1487 gimple_seq mod = NULL;
1488 int switch_id;
1489 unsigned int case_index;
1490
1491 if (q->index < 0)
1492 {
1493 x = gimple_build_assign (finally_tmp,
1494 build_int_cst (integer_type_node,
1495 return_index));
1496 gimple_seq_add_stmt (&mod, x);
1497 do_return_redirection (q, finally_label, mod);
1498 switch_id = return_index;
1499 }
1500 else
1501 {
1502 x = gimple_build_assign (finally_tmp,
1503 build_int_cst (integer_type_node, q->index));
1504 gimple_seq_add_stmt (&mod, x);
1505 do_goto_redirection (q, finally_label, mod, tf);
1506 switch_id = q->index;
1507 }
1508
1509 case_index = j + q->index;
1510 if (case_label_vec.length () <= case_index || !case_label_vec[case_index])
1511 {
1512 tree case_lab;
1513 tmp = build_int_cst (integer_type_node, switch_id);
1514 case_lab = build_case_label (tmp, NULL,
1515 create_artificial_label (tf_loc));
1516 /* We store the cont_stmt in the pointer map, so that we can recover
1517 it in the loop below. */
1518 if (!cont_map)
1519 cont_map = new hash_map<tree, gimple *>;
1520 cont_map->put (case_lab, q->cont_stmt);
1521 case_label_vec.quick_push (case_lab);
1522 }
1523 }
1524 for (j = last_case_index; j < last_case_index + nlabels; j++)
1525 {
1526 gimple *cont_stmt;
1527
1528 last_case = case_label_vec[j];
1529
1530 gcc_assert (last_case);
1531 gcc_assert (cont_map);
1532
1533 cont_stmt = *cont_map->get (last_case);
1534
1535 x = gimple_build_label (CASE_LABEL (last_case));
1536 gimple_seq_add_stmt (&switch_body, x);
1537 gimple_seq_add_stmt (&switch_body, cont_stmt);
1538 maybe_record_in_goto_queue (state, cont_stmt);
1539 }
1540 if (cont_map)
1541 delete cont_map;
1542
1543 replace_goto_queue (tf);
1544
1545 /* Make sure that the last case is the default label, as one is required.
1546 Then sort the labels, which is also required in GIMPLE. */
1547 CASE_LOW (last_case) = NULL;
1548 tree tem = case_label_vec.pop ();
1549 gcc_assert (tem == last_case);
1550 sort_case_labels (case_label_vec);
1551
1552 /* Build the switch statement, setting last_case to be the default
1553 label. */
1554 switch_stmt = gimple_build_switch (finally_tmp, last_case,
1555 case_label_vec);
1556 gimple_set_location (switch_stmt, finally_loc);
1557
1558 /* Need to link SWITCH_STMT after running replace_goto_queue
1559 due to not wanting to process the same goto stmts twice. */
1560 gimple_seq_add_stmt (&tf->top_p_seq, switch_stmt);
1561 gimple_seq_add_seq (&tf->top_p_seq, switch_body);
1562 }
1563
1564 /* Decide whether or not we are going to duplicate the finally block.
1565 There are several considerations.
1566
1567 Second, we'd like to prevent egregious code growth. One way to
1568 do this is to estimate the size of the finally block, multiply
1569 that by the number of copies we'd need to make, and compare against
1570 the estimate of the size of the switch machinery we'd have to add. */
1571
1572 static bool
decide_copy_try_finally(int ndests,bool may_throw,gimple_seq finally)1573 decide_copy_try_finally (int ndests, bool may_throw, gimple_seq finally)
1574 {
1575 int f_estimate, sw_estimate;
1576 geh_else *eh_else;
1577
1578 /* If there's an EH_ELSE involved, the exception path is separate
1579 and really doesn't come into play for this computation. */
1580 eh_else = get_eh_else (finally);
1581 if (eh_else)
1582 {
1583 ndests -= may_throw;
1584 finally = gimple_eh_else_n_body (eh_else);
1585 }
1586
1587 if (!optimize)
1588 {
1589 gimple_stmt_iterator gsi;
1590
1591 if (ndests == 1)
1592 return true;
1593
1594 for (gsi = gsi_start (finally); !gsi_end_p (gsi); gsi_next (&gsi))
1595 {
1596 /* Duplicate __builtin_stack_restore in the hope of eliminating it
1597 on the EH paths and, consequently, useless cleanups. */
1598 gimple *stmt = gsi_stmt (gsi);
1599 if (!is_gimple_debug (stmt)
1600 && !gimple_clobber_p (stmt)
1601 && !gimple_call_builtin_p (stmt, BUILT_IN_STACK_RESTORE))
1602 return false;
1603 }
1604 return true;
1605 }
1606
1607 /* Finally estimate N times, plus N gotos. */
1608 f_estimate = estimate_num_insns_seq (finally, &eni_size_weights);
1609 f_estimate = (f_estimate + 1) * ndests;
1610
1611 /* Switch statement (cost 10), N variable assignments, N gotos. */
1612 sw_estimate = 10 + 2 * ndests;
1613
1614 /* Optimize for size clearly wants our best guess. */
1615 if (optimize_function_for_size_p (cfun))
1616 return f_estimate < sw_estimate;
1617
1618 /* ??? These numbers are completely made up so far. */
1619 if (optimize > 1)
1620 return f_estimate < 100 || f_estimate < sw_estimate * 2;
1621 else
1622 return f_estimate < 40 || f_estimate * 2 < sw_estimate * 3;
1623 }
1624
1625 /* REG is current region of a LEH state.
1626 is the enclosing region for a possible cleanup region, or the region
1627 itself. Returns TRUE if such a region would be unreachable.
1628
1629 Cleanup regions within a must-not-throw region aren't actually reachable
1630 even if there are throwing stmts within them, because the personality
1631 routine will call terminate before unwinding. */
1632
1633 static bool
cleanup_is_dead_in(leh_state * state)1634 cleanup_is_dead_in (leh_state *state)
1635 {
1636 if (flag_checking)
1637 {
1638 eh_region reg = state->cur_region;
1639 while (reg && reg->type == ERT_CLEANUP)
1640 reg = reg->outer;
1641
1642 gcc_assert (reg == state->outer_non_cleanup);
1643 }
1644
1645 eh_region reg = state->outer_non_cleanup;
1646 return (reg && reg->type == ERT_MUST_NOT_THROW);
1647 }
1648
1649 /* A subroutine of lower_eh_constructs_1. Lower a GIMPLE_TRY_FINALLY nodes
1650 to a sequence of labels and blocks, plus the exception region trees
1651 that record all the magic. This is complicated by the need to
1652 arrange for the FINALLY block to be executed on all exits. */
1653
1654 static gimple_seq
lower_try_finally(struct leh_state * state,gtry * tp)1655 lower_try_finally (struct leh_state *state, gtry *tp)
1656 {
1657 struct leh_tf_state this_tf;
1658 struct leh_state this_state;
1659 int ndests;
1660 gimple_seq old_eh_seq;
1661
1662 /* Process the try block. */
1663
1664 memset (&this_tf, 0, sizeof (this_tf));
1665 this_tf.try_finally_expr = tp;
1666 this_tf.top_p = tp;
1667 this_tf.outer = state;
1668 if (using_eh_for_cleanups_p () && !cleanup_is_dead_in (state))
1669 {
1670 this_tf.region = gen_eh_region_cleanup (state->cur_region);
1671 this_state.cur_region = this_tf.region;
1672 }
1673 else
1674 {
1675 this_tf.region = NULL;
1676 this_state.cur_region = state->cur_region;
1677 }
1678
1679 this_state.outer_non_cleanup = state->outer_non_cleanup;
1680 this_state.ehp_region = state->ehp_region;
1681 this_state.tf = &this_tf;
1682
1683 old_eh_seq = eh_seq;
1684 eh_seq = NULL;
1685
1686 lower_eh_constructs_1 (&this_state, gimple_try_eval_ptr (tp));
1687
1688 /* Determine if the try block is escaped through the bottom. */
1689 this_tf.may_fallthru = gimple_seq_may_fallthru (gimple_try_eval (tp));
1690
1691 /* Determine if any exceptions are possible within the try block. */
1692 if (this_tf.region)
1693 this_tf.may_throw = eh_region_may_contain_throw (this_tf.region);
1694 if (this_tf.may_throw)
1695 honor_protect_cleanup_actions (state, &this_state, &this_tf);
1696
1697 /* Determine how many edges (still) reach the finally block. Or rather,
1698 how many destinations are reached by the finally block. Use this to
1699 determine how we process the finally block itself. */
1700
1701 ndests = this_tf.dest_array.length ();
1702 ndests += this_tf.may_fallthru;
1703 ndests += this_tf.may_return;
1704 ndests += this_tf.may_throw;
1705
1706 /* If the FINALLY block is not reachable, dike it out. */
1707 if (ndests == 0)
1708 {
1709 gimple_seq_add_seq (&this_tf.top_p_seq, gimple_try_eval (tp));
1710 gimple_try_set_cleanup (tp, NULL);
1711 }
1712 /* If the finally block doesn't fall through, then any destination
1713 we might try to impose there isn't reached either. There may be
1714 some minor amount of cleanup and redirection still needed. */
1715 else if (!gimple_seq_may_fallthru (gimple_try_cleanup (tp)))
1716 lower_try_finally_nofallthru (state, &this_tf);
1717
1718 /* We can easily special-case redirection to a single destination. */
1719 else if (ndests == 1)
1720 lower_try_finally_onedest (state, &this_tf);
1721 else if (decide_copy_try_finally (ndests, this_tf.may_throw,
1722 gimple_try_cleanup (tp)))
1723 lower_try_finally_copy (state, &this_tf);
1724 else
1725 lower_try_finally_switch (state, &this_tf);
1726
1727 /* If someone requested we add a label at the end of the transformed
1728 block, do so. */
1729 if (this_tf.fallthru_label)
1730 {
1731 /* This must be reached only if ndests == 0. */
1732 gimple *x = gimple_build_label (this_tf.fallthru_label);
1733 gimple_seq_add_stmt (&this_tf.top_p_seq, x);
1734 }
1735
1736 this_tf.dest_array.release ();
1737 free (this_tf.goto_queue);
1738 if (this_tf.goto_queue_map)
1739 delete this_tf.goto_queue_map;
1740
1741 /* If there was an old (aka outer) eh_seq, append the current eh_seq.
1742 If there was no old eh_seq, then the append is trivially already done. */
1743 if (old_eh_seq)
1744 {
1745 if (eh_seq == NULL)
1746 eh_seq = old_eh_seq;
1747 else
1748 {
1749 gimple_seq new_eh_seq = eh_seq;
1750 eh_seq = old_eh_seq;
1751 gimple_seq_add_seq (&eh_seq, new_eh_seq);
1752 }
1753 }
1754
1755 return this_tf.top_p_seq;
1756 }
1757
1758 /* A subroutine of lower_eh_constructs_1. Lower a GIMPLE_TRY_CATCH with a
1759 list of GIMPLE_CATCH to a sequence of labels and blocks, plus the
1760 exception region trees that records all the magic. */
1761
1762 static gimple_seq
lower_catch(struct leh_state * state,gtry * tp)1763 lower_catch (struct leh_state *state, gtry *tp)
1764 {
1765 eh_region try_region = NULL;
1766 struct leh_state this_state = *state;
1767 gimple_stmt_iterator gsi;
1768 tree out_label;
1769 gimple_seq new_seq, cleanup;
1770 gimple *x;
1771 geh_dispatch *eh_dispatch;
1772 location_t try_catch_loc = gimple_location (tp);
1773 location_t catch_loc = UNKNOWN_LOCATION;
1774
1775 if (flag_exceptions)
1776 {
1777 try_region = gen_eh_region_try (state->cur_region);
1778 this_state.cur_region = try_region;
1779 this_state.outer_non_cleanup = this_state.cur_region;
1780 }
1781
1782 lower_eh_constructs_1 (&this_state, gimple_try_eval_ptr (tp));
1783
1784 if (!eh_region_may_contain_throw (try_region))
1785 return gimple_try_eval (tp);
1786
1787 new_seq = NULL;
1788 eh_dispatch = gimple_build_eh_dispatch (try_region->index);
1789 gimple_seq_add_stmt (&new_seq, eh_dispatch);
1790 emit_resx (&new_seq, try_region);
1791
1792 this_state.cur_region = state->cur_region;
1793 this_state.outer_non_cleanup = state->outer_non_cleanup;
1794 this_state.ehp_region = try_region;
1795
1796 /* Add eh_seq from lowering EH in the cleanup sequence after the cleanup
1797 itself, so that e.g. for coverage purposes the nested cleanups don't
1798 appear before the cleanup body. See PR64634 for details. */
1799 gimple_seq old_eh_seq = eh_seq;
1800 eh_seq = NULL;
1801
1802 out_label = NULL;
1803 cleanup = gimple_try_cleanup (tp);
1804 for (gsi = gsi_start (cleanup);
1805 !gsi_end_p (gsi);
1806 gsi_next (&gsi))
1807 {
1808 eh_catch c;
1809 gcatch *catch_stmt;
1810 gimple_seq handler;
1811
1812 catch_stmt = as_a <gcatch *> (gsi_stmt (gsi));
1813 if (catch_loc == UNKNOWN_LOCATION)
1814 catch_loc = gimple_location (catch_stmt);
1815 c = gen_eh_region_catch (try_region, gimple_catch_types (catch_stmt));
1816
1817 handler = gimple_catch_handler (catch_stmt);
1818 lower_eh_constructs_1 (&this_state, &handler);
1819
1820 c->label = create_artificial_label (UNKNOWN_LOCATION);
1821 x = gimple_build_label (c->label);
1822 gimple_seq_add_stmt (&new_seq, x);
1823
1824 gimple_seq_add_seq (&new_seq, handler);
1825
1826 if (gimple_seq_may_fallthru (new_seq))
1827 {
1828 if (!out_label)
1829 out_label = create_artificial_label (try_catch_loc);
1830
1831 x = gimple_build_goto (out_label);
1832 gimple_seq_add_stmt (&new_seq, x);
1833 }
1834 if (!c->type_list)
1835 break;
1836 }
1837
1838 /* Try to set a location on the dispatching construct to avoid inheriting
1839 the location of the previous statement. */
1840 gimple_set_location (eh_dispatch, catch_loc);
1841
1842 gimple_try_set_cleanup (tp, new_seq);
1843
1844 gimple_seq new_eh_seq = eh_seq;
1845 eh_seq = old_eh_seq;
1846 gimple_seq ret_seq = frob_into_branch_around (tp, try_region, out_label);
1847 gimple_seq_add_seq (&eh_seq, new_eh_seq);
1848 return ret_seq;
1849 }
1850
1851 /* A subroutine of lower_eh_constructs_1. Lower a GIMPLE_TRY with a
1852 GIMPLE_EH_FILTER to a sequence of labels and blocks, plus the exception
1853 region trees that record all the magic. */
1854
1855 static gimple_seq
lower_eh_filter(struct leh_state * state,gtry * tp)1856 lower_eh_filter (struct leh_state *state, gtry *tp)
1857 {
1858 struct leh_state this_state = *state;
1859 eh_region this_region = NULL;
1860 gimple *inner, *x;
1861 gimple_seq new_seq;
1862
1863 inner = gimple_seq_first_stmt (gimple_try_cleanup (tp));
1864
1865 if (flag_exceptions)
1866 {
1867 this_region = gen_eh_region_allowed (state->cur_region,
1868 gimple_eh_filter_types (inner));
1869 this_state.cur_region = this_region;
1870 this_state.outer_non_cleanup = this_state.cur_region;
1871 }
1872
1873 lower_eh_constructs_1 (&this_state, gimple_try_eval_ptr (tp));
1874
1875 if (!eh_region_may_contain_throw (this_region))
1876 return gimple_try_eval (tp);
1877
1878 this_state.cur_region = state->cur_region;
1879 this_state.ehp_region = this_region;
1880
1881 new_seq = NULL;
1882 x = gimple_build_eh_dispatch (this_region->index);
1883 gimple_set_location (x, gimple_location (tp));
1884 gimple_seq_add_stmt (&new_seq, x);
1885 emit_resx (&new_seq, this_region);
1886
1887 this_region->u.allowed.label = create_artificial_label (UNKNOWN_LOCATION);
1888 x = gimple_build_label (this_region->u.allowed.label);
1889 gimple_seq_add_stmt (&new_seq, x);
1890
1891 lower_eh_constructs_1 (&this_state, gimple_eh_filter_failure_ptr (inner));
1892 gimple_seq_add_seq (&new_seq, gimple_eh_filter_failure (inner));
1893
1894 gimple_try_set_cleanup (tp, new_seq);
1895
1896 return frob_into_branch_around (tp, this_region, NULL);
1897 }
1898
1899 /* A subroutine of lower_eh_constructs_1. Lower a GIMPLE_TRY with
1900 an GIMPLE_EH_MUST_NOT_THROW to a sequence of labels and blocks,
1901 plus the exception region trees that record all the magic. */
1902
1903 static gimple_seq
lower_eh_must_not_throw(struct leh_state * state,gtry * tp)1904 lower_eh_must_not_throw (struct leh_state *state, gtry *tp)
1905 {
1906 struct leh_state this_state = *state;
1907
1908 if (flag_exceptions)
1909 {
1910 gimple *inner = gimple_seq_first_stmt (gimple_try_cleanup (tp));
1911 eh_region this_region;
1912
1913 this_region = gen_eh_region_must_not_throw (state->cur_region);
1914 this_region->u.must_not_throw.failure_decl
1915 = gimple_eh_must_not_throw_fndecl (
1916 as_a <geh_mnt *> (inner));
1917 this_region->u.must_not_throw.failure_loc
1918 = LOCATION_LOCUS (gimple_location (tp));
1919
1920 /* In order to get mangling applied to this decl, we must mark it
1921 used now. Otherwise, pass_ipa_free_lang_data won't think it
1922 needs to happen. */
1923 TREE_USED (this_region->u.must_not_throw.failure_decl) = 1;
1924
1925 this_state.cur_region = this_region;
1926 this_state.outer_non_cleanup = this_state.cur_region;
1927 }
1928
1929 lower_eh_constructs_1 (&this_state, gimple_try_eval_ptr (tp));
1930
1931 return gimple_try_eval (tp);
1932 }
1933
1934 /* Implement a cleanup expression. This is similar to try-finally,
1935 except that we only execute the cleanup block for exception edges. */
1936
1937 static gimple_seq
lower_cleanup(struct leh_state * state,gtry * tp)1938 lower_cleanup (struct leh_state *state, gtry *tp)
1939 {
1940 struct leh_state this_state = *state;
1941 eh_region this_region = NULL;
1942 struct leh_tf_state fake_tf;
1943 gimple_seq result;
1944 bool cleanup_dead = cleanup_is_dead_in (state);
1945
1946 if (flag_exceptions && !cleanup_dead)
1947 {
1948 this_region = gen_eh_region_cleanup (state->cur_region);
1949 this_state.cur_region = this_region;
1950 this_state.outer_non_cleanup = state->outer_non_cleanup;
1951 }
1952
1953 lower_eh_constructs_1 (&this_state, gimple_try_eval_ptr (tp));
1954
1955 if (cleanup_dead || !eh_region_may_contain_throw (this_region))
1956 return gimple_try_eval (tp);
1957
1958 /* Build enough of a try-finally state so that we can reuse
1959 honor_protect_cleanup_actions. */
1960 memset (&fake_tf, 0, sizeof (fake_tf));
1961 fake_tf.top_p = fake_tf.try_finally_expr = tp;
1962 fake_tf.outer = state;
1963 fake_tf.region = this_region;
1964 fake_tf.may_fallthru = gimple_seq_may_fallthru (gimple_try_eval (tp));
1965 fake_tf.may_throw = true;
1966
1967 honor_protect_cleanup_actions (state, NULL, &fake_tf);
1968
1969 if (fake_tf.may_throw)
1970 {
1971 /* In this case honor_protect_cleanup_actions had nothing to do,
1972 and we should process this normally. */
1973 lower_eh_constructs_1 (state, gimple_try_cleanup_ptr (tp));
1974 result = frob_into_branch_around (tp, this_region,
1975 fake_tf.fallthru_label);
1976 }
1977 else
1978 {
1979 /* In this case honor_protect_cleanup_actions did nearly all of
1980 the work. All we have left is to append the fallthru_label. */
1981
1982 result = gimple_try_eval (tp);
1983 if (fake_tf.fallthru_label)
1984 {
1985 gimple *x = gimple_build_label (fake_tf.fallthru_label);
1986 gimple_seq_add_stmt (&result, x);
1987 }
1988 }
1989 return result;
1990 }
1991
1992 /* Main loop for lowering eh constructs. Also moves gsi to the next
1993 statement. */
1994
1995 static void
lower_eh_constructs_2(struct leh_state * state,gimple_stmt_iterator * gsi)1996 lower_eh_constructs_2 (struct leh_state *state, gimple_stmt_iterator *gsi)
1997 {
1998 gimple_seq replace;
1999 gimple *x;
2000 gimple *stmt = gsi_stmt (*gsi);
2001
2002 switch (gimple_code (stmt))
2003 {
2004 case GIMPLE_CALL:
2005 {
2006 tree fndecl = gimple_call_fndecl (stmt);
2007 tree rhs, lhs;
2008
2009 if (fndecl && fndecl_built_in_p (fndecl, BUILT_IN_NORMAL))
2010 switch (DECL_FUNCTION_CODE (fndecl))
2011 {
2012 case BUILT_IN_EH_POINTER:
2013 /* The front end may have generated a call to
2014 __builtin_eh_pointer (0) within a catch region. Replace
2015 this zero argument with the current catch region number. */
2016 if (state->ehp_region)
2017 {
2018 tree nr = build_int_cst (integer_type_node,
2019 state->ehp_region->index);
2020 gimple_call_set_arg (stmt, 0, nr);
2021 }
2022 else
2023 {
2024 /* The user has dome something silly. Remove it. */
2025 rhs = null_pointer_node;
2026 goto do_replace;
2027 }
2028 break;
2029
2030 case BUILT_IN_EH_FILTER:
2031 /* ??? This should never appear, but since it's a builtin it
2032 is accessible to abuse by users. Just remove it and
2033 replace the use with the arbitrary value zero. */
2034 rhs = build_int_cst (TREE_TYPE (TREE_TYPE (fndecl)), 0);
2035 do_replace:
2036 lhs = gimple_call_lhs (stmt);
2037 x = gimple_build_assign (lhs, rhs);
2038 gsi_insert_before (gsi, x, GSI_SAME_STMT);
2039 /* FALLTHRU */
2040
2041 case BUILT_IN_EH_COPY_VALUES:
2042 /* Likewise this should not appear. Remove it. */
2043 gsi_remove (gsi, true);
2044 return;
2045
2046 default:
2047 break;
2048 }
2049 }
2050 /* FALLTHRU */
2051
2052 case GIMPLE_ASSIGN:
2053 /* If the stmt can throw, use a new temporary for the assignment
2054 to a LHS. This makes sure the old value of the LHS is
2055 available on the EH edge. Only do so for statements that
2056 potentially fall through (no noreturn calls e.g.), otherwise
2057 this new assignment might create fake fallthru regions. */
2058 if (stmt_could_throw_p (cfun, stmt)
2059 && gimple_has_lhs (stmt)
2060 && gimple_stmt_may_fallthru (stmt)
2061 && !tree_could_throw_p (gimple_get_lhs (stmt))
2062 && is_gimple_reg_type (TREE_TYPE (gimple_get_lhs (stmt))))
2063 {
2064 tree lhs = gimple_get_lhs (stmt);
2065 tree tmp = create_tmp_var (TREE_TYPE (lhs));
2066 gimple *s = gimple_build_assign (lhs, tmp);
2067 gimple_set_location (s, gimple_location (stmt));
2068 gimple_set_block (s, gimple_block (stmt));
2069 gimple_set_lhs (stmt, tmp);
2070 gsi_insert_after (gsi, s, GSI_SAME_STMT);
2071 }
2072 /* Look for things that can throw exceptions, and record them. */
2073 if (state->cur_region && stmt_could_throw_p (cfun, stmt))
2074 {
2075 record_stmt_eh_region (state->cur_region, stmt);
2076 note_eh_region_may_contain_throw (state->cur_region);
2077 }
2078 break;
2079
2080 case GIMPLE_COND:
2081 case GIMPLE_GOTO:
2082 case GIMPLE_RETURN:
2083 maybe_record_in_goto_queue (state, stmt);
2084 break;
2085
2086 case GIMPLE_SWITCH:
2087 verify_norecord_switch_expr (state, as_a <gswitch *> (stmt));
2088 break;
2089
2090 case GIMPLE_TRY:
2091 {
2092 gtry *try_stmt = as_a <gtry *> (stmt);
2093 if (gimple_try_kind (try_stmt) == GIMPLE_TRY_FINALLY)
2094 replace = lower_try_finally (state, try_stmt);
2095 else
2096 {
2097 x = gimple_seq_first_stmt (gimple_try_cleanup (try_stmt));
2098 if (!x)
2099 {
2100 replace = gimple_try_eval (try_stmt);
2101 lower_eh_constructs_1 (state, &replace);
2102 }
2103 else
2104 switch (gimple_code (x))
2105 {
2106 case GIMPLE_CATCH:
2107 replace = lower_catch (state, try_stmt);
2108 break;
2109 case GIMPLE_EH_FILTER:
2110 replace = lower_eh_filter (state, try_stmt);
2111 break;
2112 case GIMPLE_EH_MUST_NOT_THROW:
2113 replace = lower_eh_must_not_throw (state, try_stmt);
2114 break;
2115 case GIMPLE_EH_ELSE:
2116 /* This code is only valid with GIMPLE_TRY_FINALLY. */
2117 gcc_unreachable ();
2118 default:
2119 replace = lower_cleanup (state, try_stmt);
2120 break;
2121 }
2122 }
2123 }
2124
2125 /* Remove the old stmt and insert the transformed sequence
2126 instead. */
2127 gsi_insert_seq_before (gsi, replace, GSI_SAME_STMT);
2128 gsi_remove (gsi, true);
2129
2130 /* Return since we don't want gsi_next () */
2131 return;
2132
2133 case GIMPLE_EH_ELSE:
2134 /* We should be eliminating this in lower_try_finally et al. */
2135 gcc_unreachable ();
2136
2137 default:
2138 /* A type, a decl, or some kind of statement that we're not
2139 interested in. Don't walk them. */
2140 break;
2141 }
2142
2143 gsi_next (gsi);
2144 }
2145
2146 /* A helper to unwrap a gimple_seq and feed stmts to lower_eh_constructs_2. */
2147
2148 static void
lower_eh_constructs_1(struct leh_state * state,gimple_seq * pseq)2149 lower_eh_constructs_1 (struct leh_state *state, gimple_seq *pseq)
2150 {
2151 gimple_stmt_iterator gsi;
2152 for (gsi = gsi_start (*pseq); !gsi_end_p (gsi);)
2153 lower_eh_constructs_2 (state, &gsi);
2154 }
2155
2156 namespace {
2157
2158 const pass_data pass_data_lower_eh =
2159 {
2160 GIMPLE_PASS, /* type */
2161 "eh", /* name */
2162 OPTGROUP_NONE, /* optinfo_flags */
2163 TV_TREE_EH, /* tv_id */
2164 PROP_gimple_lcf, /* properties_required */
2165 PROP_gimple_leh, /* properties_provided */
2166 0, /* properties_destroyed */
2167 0, /* todo_flags_start */
2168 0, /* todo_flags_finish */
2169 };
2170
2171 class pass_lower_eh : public gimple_opt_pass
2172 {
2173 public:
pass_lower_eh(gcc::context * ctxt)2174 pass_lower_eh (gcc::context *ctxt)
2175 : gimple_opt_pass (pass_data_lower_eh, ctxt)
2176 {}
2177
2178 /* opt_pass methods: */
2179 virtual unsigned int execute (function *);
2180
2181 }; // class pass_lower_eh
2182
2183 unsigned int
execute(function * fun)2184 pass_lower_eh::execute (function *fun)
2185 {
2186 struct leh_state null_state;
2187 gimple_seq bodyp;
2188
2189 bodyp = gimple_body (current_function_decl);
2190 if (bodyp == NULL)
2191 return 0;
2192
2193 finally_tree = new hash_table<finally_tree_hasher> (31);
2194 eh_region_may_contain_throw_map = BITMAP_ALLOC (NULL);
2195 memset (&null_state, 0, sizeof (null_state));
2196
2197 collect_finally_tree_1 (bodyp, NULL);
2198 lower_eh_constructs_1 (&null_state, &bodyp);
2199 gimple_set_body (current_function_decl, bodyp);
2200
2201 /* We assume there's a return statement, or something, at the end of
2202 the function, and thus ploping the EH sequence afterward won't
2203 change anything. */
2204 gcc_assert (!gimple_seq_may_fallthru (bodyp));
2205 gimple_seq_add_seq (&bodyp, eh_seq);
2206
2207 /* We assume that since BODYP already existed, adding EH_SEQ to it
2208 didn't change its value, and we don't have to re-set the function. */
2209 gcc_assert (bodyp == gimple_body (current_function_decl));
2210
2211 delete finally_tree;
2212 finally_tree = NULL;
2213 BITMAP_FREE (eh_region_may_contain_throw_map);
2214 eh_seq = NULL;
2215
2216 /* If this function needs a language specific EH personality routine
2217 and the frontend didn't already set one do so now. */
2218 if (function_needs_eh_personality (fun) == eh_personality_lang
2219 && !DECL_FUNCTION_PERSONALITY (current_function_decl))
2220 DECL_FUNCTION_PERSONALITY (current_function_decl)
2221 = lang_hooks.eh_personality ();
2222
2223 return 0;
2224 }
2225
2226 } // anon namespace
2227
2228 gimple_opt_pass *
make_pass_lower_eh(gcc::context * ctxt)2229 make_pass_lower_eh (gcc::context *ctxt)
2230 {
2231 return new pass_lower_eh (ctxt);
2232 }
2233
2234 /* Create the multiple edges from an EH_DISPATCH statement to all of
2235 the possible handlers for its EH region. Return true if there's
2236 no fallthru edge; false if there is. */
2237
2238 bool
make_eh_dispatch_edges(geh_dispatch * stmt)2239 make_eh_dispatch_edges (geh_dispatch *stmt)
2240 {
2241 eh_region r;
2242 eh_catch c;
2243 basic_block src, dst;
2244
2245 r = get_eh_region_from_number (gimple_eh_dispatch_region (stmt));
2246 src = gimple_bb (stmt);
2247
2248 switch (r->type)
2249 {
2250 case ERT_TRY:
2251 for (c = r->u.eh_try.first_catch; c ; c = c->next_catch)
2252 {
2253 dst = label_to_block (cfun, c->label);
2254 make_edge (src, dst, 0);
2255
2256 /* A catch-all handler doesn't have a fallthru. */
2257 if (c->type_list == NULL)
2258 return false;
2259 }
2260 break;
2261
2262 case ERT_ALLOWED_EXCEPTIONS:
2263 dst = label_to_block (cfun, r->u.allowed.label);
2264 make_edge (src, dst, 0);
2265 break;
2266
2267 default:
2268 gcc_unreachable ();
2269 }
2270
2271 return true;
2272 }
2273
2274 /* Create the single EH edge from STMT to its nearest landing pad,
2275 if there is such a landing pad within the current function. */
2276
2277 void
make_eh_edges(gimple * stmt)2278 make_eh_edges (gimple *stmt)
2279 {
2280 basic_block src, dst;
2281 eh_landing_pad lp;
2282 int lp_nr;
2283
2284 lp_nr = lookup_stmt_eh_lp (stmt);
2285 if (lp_nr <= 0)
2286 return;
2287
2288 lp = get_eh_landing_pad_from_number (lp_nr);
2289 gcc_assert (lp != NULL);
2290
2291 src = gimple_bb (stmt);
2292 dst = label_to_block (cfun, lp->post_landing_pad);
2293 make_edge (src, dst, EDGE_EH);
2294 }
2295
2296 /* Do the work in redirecting EDGE_IN to NEW_BB within the EH region tree;
2297 do not actually perform the final edge redirection.
2298
2299 CHANGE_REGION is true when we're being called from cleanup_empty_eh and
2300 we intend to change the destination EH region as well; this means
2301 EH_LANDING_PAD_NR must already be set on the destination block label.
2302 If false, we're being called from generic cfg manipulation code and we
2303 should preserve our place within the region tree. */
2304
2305 static void
redirect_eh_edge_1(edge edge_in,basic_block new_bb,bool change_region)2306 redirect_eh_edge_1 (edge edge_in, basic_block new_bb, bool change_region)
2307 {
2308 eh_landing_pad old_lp, new_lp;
2309 basic_block old_bb;
2310 gimple *throw_stmt;
2311 int old_lp_nr, new_lp_nr;
2312 tree old_label, new_label;
2313 edge_iterator ei;
2314 edge e;
2315
2316 old_bb = edge_in->dest;
2317 old_label = gimple_block_label (old_bb);
2318 old_lp_nr = EH_LANDING_PAD_NR (old_label);
2319 gcc_assert (old_lp_nr > 0);
2320 old_lp = get_eh_landing_pad_from_number (old_lp_nr);
2321
2322 throw_stmt = last_stmt (edge_in->src);
2323 gcc_checking_assert (lookup_stmt_eh_lp (throw_stmt) == old_lp_nr);
2324
2325 new_label = gimple_block_label (new_bb);
2326
2327 /* Look for an existing region that might be using NEW_BB already. */
2328 new_lp_nr = EH_LANDING_PAD_NR (new_label);
2329 if (new_lp_nr)
2330 {
2331 new_lp = get_eh_landing_pad_from_number (new_lp_nr);
2332 gcc_assert (new_lp);
2333
2334 /* Unless CHANGE_REGION is true, the new and old landing pad
2335 had better be associated with the same EH region. */
2336 gcc_assert (change_region || new_lp->region == old_lp->region);
2337 }
2338 else
2339 {
2340 new_lp = NULL;
2341 gcc_assert (!change_region);
2342 }
2343
2344 /* Notice when we redirect the last EH edge away from OLD_BB. */
2345 FOR_EACH_EDGE (e, ei, old_bb->preds)
2346 if (e != edge_in && (e->flags & EDGE_EH))
2347 break;
2348
2349 if (new_lp)
2350 {
2351 /* NEW_LP already exists. If there are still edges into OLD_LP,
2352 there's nothing to do with the EH tree. If there are no more
2353 edges into OLD_LP, then we want to remove OLD_LP as it is unused.
2354 If CHANGE_REGION is true, then our caller is expecting to remove
2355 the landing pad. */
2356 if (e == NULL && !change_region)
2357 remove_eh_landing_pad (old_lp);
2358 }
2359 else
2360 {
2361 /* No correct landing pad exists. If there are no more edges
2362 into OLD_LP, then we can simply re-use the existing landing pad.
2363 Otherwise, we have to create a new landing pad. */
2364 if (e == NULL)
2365 {
2366 EH_LANDING_PAD_NR (old_lp->post_landing_pad) = 0;
2367 new_lp = old_lp;
2368 }
2369 else
2370 new_lp = gen_eh_landing_pad (old_lp->region);
2371 new_lp->post_landing_pad = new_label;
2372 EH_LANDING_PAD_NR (new_label) = new_lp->index;
2373 }
2374
2375 /* Maybe move the throwing statement to the new region. */
2376 if (old_lp != new_lp)
2377 {
2378 remove_stmt_from_eh_lp (throw_stmt);
2379 add_stmt_to_eh_lp (throw_stmt, new_lp->index);
2380 }
2381 }
2382
2383 /* Redirect EH edge E to NEW_BB. */
2384
2385 edge
redirect_eh_edge(edge edge_in,basic_block new_bb)2386 redirect_eh_edge (edge edge_in, basic_block new_bb)
2387 {
2388 redirect_eh_edge_1 (edge_in, new_bb, false);
2389 return ssa_redirect_edge (edge_in, new_bb);
2390 }
2391
2392 /* This is a subroutine of gimple_redirect_edge_and_branch. Update the
2393 labels for redirecting a non-fallthru EH_DISPATCH edge E to NEW_BB.
2394 The actual edge update will happen in the caller. */
2395
2396 void
redirect_eh_dispatch_edge(geh_dispatch * stmt,edge e,basic_block new_bb)2397 redirect_eh_dispatch_edge (geh_dispatch *stmt, edge e, basic_block new_bb)
2398 {
2399 tree new_lab = gimple_block_label (new_bb);
2400 bool any_changed = false;
2401 basic_block old_bb;
2402 eh_region r;
2403 eh_catch c;
2404
2405 r = get_eh_region_from_number (gimple_eh_dispatch_region (stmt));
2406 switch (r->type)
2407 {
2408 case ERT_TRY:
2409 for (c = r->u.eh_try.first_catch; c ; c = c->next_catch)
2410 {
2411 old_bb = label_to_block (cfun, c->label);
2412 if (old_bb == e->dest)
2413 {
2414 c->label = new_lab;
2415 any_changed = true;
2416 }
2417 }
2418 break;
2419
2420 case ERT_ALLOWED_EXCEPTIONS:
2421 old_bb = label_to_block (cfun, r->u.allowed.label);
2422 gcc_assert (old_bb == e->dest);
2423 r->u.allowed.label = new_lab;
2424 any_changed = true;
2425 break;
2426
2427 default:
2428 gcc_unreachable ();
2429 }
2430
2431 gcc_assert (any_changed);
2432 }
2433
2434 /* Helper function for operation_could_trap_p and stmt_could_throw_p. */
2435
2436 bool
operation_could_trap_helper_p(enum tree_code op,bool fp_operation,bool honor_trapv,bool honor_nans,bool honor_snans,tree divisor,bool * handled)2437 operation_could_trap_helper_p (enum tree_code op,
2438 bool fp_operation,
2439 bool honor_trapv,
2440 bool honor_nans,
2441 bool honor_snans,
2442 tree divisor,
2443 bool *handled)
2444 {
2445 *handled = true;
2446 switch (op)
2447 {
2448 case TRUNC_DIV_EXPR:
2449 case CEIL_DIV_EXPR:
2450 case FLOOR_DIV_EXPR:
2451 case ROUND_DIV_EXPR:
2452 case EXACT_DIV_EXPR:
2453 case CEIL_MOD_EXPR:
2454 case FLOOR_MOD_EXPR:
2455 case ROUND_MOD_EXPR:
2456 case TRUNC_MOD_EXPR:
2457 if (!TREE_CONSTANT (divisor) || integer_zerop (divisor))
2458 return true;
2459 if (TREE_CODE (divisor) == VECTOR_CST)
2460 {
2461 /* Inspired by initializer_each_zero_or_onep. */
2462 unsigned HOST_WIDE_INT nelts = vector_cst_encoded_nelts (divisor);
2463 if (VECTOR_CST_STEPPED_P (divisor)
2464 && !TYPE_VECTOR_SUBPARTS (TREE_TYPE (divisor))
2465 .is_constant (&nelts))
2466 return true;
2467 for (unsigned int i = 0; i < nelts; ++i)
2468 {
2469 tree elt = vector_cst_elt (divisor, i);
2470 if (integer_zerop (elt))
2471 return true;
2472 }
2473 }
2474 return false;
2475
2476 case RDIV_EXPR:
2477 if (fp_operation)
2478 {
2479 if (honor_snans)
2480 return true;
2481 return flag_trapping_math;
2482 }
2483 /* Fixed point operations also use RDIV_EXPR. */
2484 if (!TREE_CONSTANT (divisor) || fixed_zerop (divisor))
2485 return true;
2486 return false;
2487
2488 case LT_EXPR:
2489 case LE_EXPR:
2490 case GT_EXPR:
2491 case GE_EXPR:
2492 case LTGT_EXPR:
2493 /* Some floating point comparisons may trap. */
2494 return honor_nans;
2495
2496 case EQ_EXPR:
2497 case NE_EXPR:
2498 case UNORDERED_EXPR:
2499 case ORDERED_EXPR:
2500 case UNLT_EXPR:
2501 case UNLE_EXPR:
2502 case UNGT_EXPR:
2503 case UNGE_EXPR:
2504 case UNEQ_EXPR:
2505 return honor_snans;
2506
2507 case NEGATE_EXPR:
2508 case ABS_EXPR:
2509 case CONJ_EXPR:
2510 /* These operations don't trap with floating point. */
2511 if (honor_trapv)
2512 return true;
2513 return false;
2514
2515 case ABSU_EXPR:
2516 /* ABSU_EXPR never traps. */
2517 return false;
2518
2519 case PLUS_EXPR:
2520 case MINUS_EXPR:
2521 case MULT_EXPR:
2522 /* Any floating arithmetic may trap. */
2523 if (fp_operation && flag_trapping_math)
2524 return true;
2525 if (honor_trapv)
2526 return true;
2527 return false;
2528
2529 case COMPLEX_EXPR:
2530 case CONSTRUCTOR:
2531 /* Constructing an object cannot trap. */
2532 return false;
2533
2534 case COND_EXPR:
2535 case VEC_COND_EXPR:
2536 /* Whether *COND_EXPR can trap depends on whether the
2537 first argument can trap, so signal it as not handled.
2538 Whether lhs is floating or not doesn't matter. */
2539 *handled = false;
2540 return false;
2541
2542 default:
2543 /* Any floating arithmetic may trap. */
2544 if (fp_operation && flag_trapping_math)
2545 return true;
2546
2547 *handled = false;
2548 return false;
2549 }
2550 }
2551
2552 /* Return true if operation OP may trap. FP_OPERATION is true if OP is applied
2553 on floating-point values. HONOR_TRAPV is true if OP is applied on integer
2554 type operands that may trap. If OP is a division operator, DIVISOR contains
2555 the value of the divisor. */
2556
2557 bool
operation_could_trap_p(enum tree_code op,bool fp_operation,bool honor_trapv,tree divisor)2558 operation_could_trap_p (enum tree_code op, bool fp_operation, bool honor_trapv,
2559 tree divisor)
2560 {
2561 bool honor_nans = (fp_operation && flag_trapping_math
2562 && !flag_finite_math_only);
2563 bool honor_snans = fp_operation && flag_signaling_nans != 0;
2564 bool handled;
2565
2566 /* This function cannot tell whether or not COND_EXPR could trap,
2567 because that depends on its condition op. */
2568 gcc_assert (op != COND_EXPR);
2569
2570 if (TREE_CODE_CLASS (op) != tcc_comparison
2571 && TREE_CODE_CLASS (op) != tcc_unary
2572 && TREE_CODE_CLASS (op) != tcc_binary)
2573 return false;
2574
2575 return operation_could_trap_helper_p (op, fp_operation, honor_trapv,
2576 honor_nans, honor_snans, divisor,
2577 &handled);
2578 }
2579
2580
2581 /* Returns true if it is possible to prove that the index of
2582 an array access REF (an ARRAY_REF expression) falls into the
2583 array bounds. */
2584
2585 static bool
in_array_bounds_p(tree ref)2586 in_array_bounds_p (tree ref)
2587 {
2588 tree idx = TREE_OPERAND (ref, 1);
2589 tree min, max;
2590
2591 if (TREE_CODE (idx) != INTEGER_CST)
2592 return false;
2593
2594 min = array_ref_low_bound (ref);
2595 max = array_ref_up_bound (ref);
2596 if (!min
2597 || !max
2598 || TREE_CODE (min) != INTEGER_CST
2599 || TREE_CODE (max) != INTEGER_CST)
2600 return false;
2601
2602 if (tree_int_cst_lt (idx, min)
2603 || tree_int_cst_lt (max, idx))
2604 return false;
2605
2606 return true;
2607 }
2608
2609 /* Returns true if it is possible to prove that the range of
2610 an array access REF (an ARRAY_RANGE_REF expression) falls
2611 into the array bounds. */
2612
2613 static bool
range_in_array_bounds_p(tree ref)2614 range_in_array_bounds_p (tree ref)
2615 {
2616 tree domain_type = TYPE_DOMAIN (TREE_TYPE (ref));
2617 tree range_min, range_max, min, max;
2618
2619 range_min = TYPE_MIN_VALUE (domain_type);
2620 range_max = TYPE_MAX_VALUE (domain_type);
2621 if (!range_min
2622 || !range_max
2623 || TREE_CODE (range_min) != INTEGER_CST
2624 || TREE_CODE (range_max) != INTEGER_CST)
2625 return false;
2626
2627 min = array_ref_low_bound (ref);
2628 max = array_ref_up_bound (ref);
2629 if (!min
2630 || !max
2631 || TREE_CODE (min) != INTEGER_CST
2632 || TREE_CODE (max) != INTEGER_CST)
2633 return false;
2634
2635 if (tree_int_cst_lt (range_min, min)
2636 || tree_int_cst_lt (max, range_max))
2637 return false;
2638
2639 return true;
2640 }
2641
2642 /* Return true if EXPR can trap, as in dereferencing an invalid pointer
2643 location or floating point arithmetic. C.f. the rtl version, may_trap_p.
2644 This routine expects only GIMPLE lhs or rhs input. */
2645
2646 bool
tree_could_trap_p(tree expr)2647 tree_could_trap_p (tree expr)
2648 {
2649 enum tree_code code;
2650 bool fp_operation = false;
2651 bool honor_trapv = false;
2652 tree t, base, div = NULL_TREE;
2653
2654 if (!expr)
2655 return false;
2656
2657 /* In COND_EXPR and VEC_COND_EXPR only the condition may trap, but
2658 they won't appear as operands in GIMPLE form, so this is just for the
2659 GENERIC uses where it needs to recurse on the operands and so
2660 *COND_EXPR itself doesn't trap. */
2661 if (TREE_CODE (expr) == COND_EXPR || TREE_CODE (expr) == VEC_COND_EXPR)
2662 return false;
2663
2664 code = TREE_CODE (expr);
2665 t = TREE_TYPE (expr);
2666
2667 if (t)
2668 {
2669 if (COMPARISON_CLASS_P (expr))
2670 fp_operation = FLOAT_TYPE_P (TREE_TYPE (TREE_OPERAND (expr, 0)));
2671 else
2672 fp_operation = FLOAT_TYPE_P (t);
2673 honor_trapv = INTEGRAL_TYPE_P (t) && TYPE_OVERFLOW_TRAPS (t);
2674 }
2675
2676 if (TREE_CODE_CLASS (code) == tcc_binary)
2677 div = TREE_OPERAND (expr, 1);
2678 if (operation_could_trap_p (code, fp_operation, honor_trapv, div))
2679 return true;
2680
2681 restart:
2682 switch (code)
2683 {
2684 case COMPONENT_REF:
2685 case REALPART_EXPR:
2686 case IMAGPART_EXPR:
2687 case BIT_FIELD_REF:
2688 case VIEW_CONVERT_EXPR:
2689 case WITH_SIZE_EXPR:
2690 expr = TREE_OPERAND (expr, 0);
2691 code = TREE_CODE (expr);
2692 goto restart;
2693
2694 case ARRAY_RANGE_REF:
2695 base = TREE_OPERAND (expr, 0);
2696 if (tree_could_trap_p (base))
2697 return true;
2698 if (TREE_THIS_NOTRAP (expr))
2699 return false;
2700 return !range_in_array_bounds_p (expr);
2701
2702 case ARRAY_REF:
2703 base = TREE_OPERAND (expr, 0);
2704 if (tree_could_trap_p (base))
2705 return true;
2706 if (TREE_THIS_NOTRAP (expr))
2707 return false;
2708 return !in_array_bounds_p (expr);
2709
2710 case TARGET_MEM_REF:
2711 case MEM_REF:
2712 if (TREE_CODE (TREE_OPERAND (expr, 0)) == ADDR_EXPR
2713 && tree_could_trap_p (TREE_OPERAND (TREE_OPERAND (expr, 0), 0)))
2714 return true;
2715 if (TREE_THIS_NOTRAP (expr))
2716 return false;
2717 /* We cannot prove that the access is in-bounds when we have
2718 variable-index TARGET_MEM_REFs. */
2719 if (code == TARGET_MEM_REF
2720 && (TMR_INDEX (expr) || TMR_INDEX2 (expr)))
2721 return true;
2722 if (TREE_CODE (TREE_OPERAND (expr, 0)) == ADDR_EXPR)
2723 {
2724 tree base = TREE_OPERAND (TREE_OPERAND (expr, 0), 0);
2725 poly_offset_int off = mem_ref_offset (expr);
2726 if (maybe_lt (off, 0))
2727 return true;
2728 if (TREE_CODE (base) == STRING_CST)
2729 return maybe_le (TREE_STRING_LENGTH (base), off);
2730 tree size = DECL_SIZE_UNIT (base);
2731 if (size == NULL_TREE
2732 || !poly_int_tree_p (size)
2733 || maybe_le (wi::to_poly_offset (size), off))
2734 return true;
2735 /* Now we are sure the first byte of the access is inside
2736 the object. */
2737 return false;
2738 }
2739 return true;
2740
2741 case INDIRECT_REF:
2742 return !TREE_THIS_NOTRAP (expr);
2743
2744 case ASM_EXPR:
2745 return TREE_THIS_VOLATILE (expr);
2746
2747 case CALL_EXPR:
2748 /* Internal function calls do not trap. */
2749 if (CALL_EXPR_FN (expr) == NULL_TREE)
2750 return false;
2751 t = get_callee_fndecl (expr);
2752 /* Assume that indirect and calls to weak functions may trap. */
2753 if (!t || !DECL_P (t))
2754 return true;
2755 if (DECL_WEAK (t))
2756 return tree_could_trap_p (t);
2757 return false;
2758
2759 case FUNCTION_DECL:
2760 /* Assume that accesses to weak functions may trap, unless we know
2761 they are certainly defined in current TU or in some other
2762 LTO partition. */
2763 if (DECL_WEAK (expr) && !DECL_COMDAT (expr) && DECL_EXTERNAL (expr))
2764 {
2765 cgraph_node *node = cgraph_node::get (expr);
2766 if (node)
2767 node = node->function_symbol ();
2768 return !(node && node->in_other_partition);
2769 }
2770 return false;
2771
2772 case VAR_DECL:
2773 /* Assume that accesses to weak vars may trap, unless we know
2774 they are certainly defined in current TU or in some other
2775 LTO partition. */
2776 if (DECL_WEAK (expr) && !DECL_COMDAT (expr) && DECL_EXTERNAL (expr))
2777 {
2778 varpool_node *node = varpool_node::get (expr);
2779 if (node)
2780 node = node->ultimate_alias_target ();
2781 return !(node && node->in_other_partition);
2782 }
2783 return false;
2784
2785 default:
2786 return false;
2787 }
2788 }
2789
2790 /* Return non-NULL if there is an integer operation with trapping overflow
2791 we can rewrite into non-trapping. Called via walk_tree from
2792 rewrite_to_non_trapping_overflow. */
2793
2794 static tree
find_trapping_overflow(tree * tp,int * walk_subtrees,void * data)2795 find_trapping_overflow (tree *tp, int *walk_subtrees, void *data)
2796 {
2797 if (EXPR_P (*tp)
2798 && ANY_INTEGRAL_TYPE_P (TREE_TYPE (*tp))
2799 && !operation_no_trapping_overflow (TREE_TYPE (*tp), TREE_CODE (*tp)))
2800 return *tp;
2801 if (IS_TYPE_OR_DECL_P (*tp)
2802 || (TREE_CODE (*tp) == SAVE_EXPR && data == NULL))
2803 *walk_subtrees = 0;
2804 return NULL_TREE;
2805 }
2806
2807 /* Rewrite selected operations into unsigned arithmetics, so that they
2808 don't trap on overflow. */
2809
2810 static tree
replace_trapping_overflow(tree * tp,int * walk_subtrees,void * data)2811 replace_trapping_overflow (tree *tp, int *walk_subtrees, void *data)
2812 {
2813 if (find_trapping_overflow (tp, walk_subtrees, data))
2814 {
2815 tree type = TREE_TYPE (*tp);
2816 tree utype = unsigned_type_for (type);
2817 *walk_subtrees = 0;
2818 int len = TREE_OPERAND_LENGTH (*tp);
2819 for (int i = 0; i < len; ++i)
2820 walk_tree (&TREE_OPERAND (*tp, i), replace_trapping_overflow,
2821 data, (hash_set<tree> *) data);
2822
2823 if (TREE_CODE (*tp) == ABS_EXPR)
2824 {
2825 TREE_SET_CODE (*tp, ABSU_EXPR);
2826 TREE_TYPE (*tp) = utype;
2827 *tp = fold_convert (type, *tp);
2828 }
2829 else
2830 {
2831 TREE_TYPE (*tp) = utype;
2832 len = TREE_OPERAND_LENGTH (*tp);
2833 for (int i = 0; i < len; ++i)
2834 TREE_OPERAND (*tp, i)
2835 = fold_convert (utype, TREE_OPERAND (*tp, i));
2836 *tp = fold_convert (type, *tp);
2837 }
2838 }
2839 return NULL_TREE;
2840 }
2841
2842 /* If any subexpression of EXPR can trap due to -ftrapv, rewrite it
2843 using unsigned arithmetics to avoid traps in it. */
2844
2845 tree
rewrite_to_non_trapping_overflow(tree expr)2846 rewrite_to_non_trapping_overflow (tree expr)
2847 {
2848 if (!flag_trapv)
2849 return expr;
2850 hash_set<tree> pset;
2851 if (!walk_tree (&expr, find_trapping_overflow, &pset, &pset))
2852 return expr;
2853 expr = unshare_expr (expr);
2854 pset.empty ();
2855 walk_tree (&expr, replace_trapping_overflow, &pset, &pset);
2856 return expr;
2857 }
2858
2859 /* Helper for stmt_could_throw_p. Return true if STMT (assumed to be a
2860 an assignment or a conditional) may throw. */
2861
2862 static bool
stmt_could_throw_1_p(gassign * stmt)2863 stmt_could_throw_1_p (gassign *stmt)
2864 {
2865 enum tree_code code = gimple_assign_rhs_code (stmt);
2866 bool honor_nans = false;
2867 bool honor_snans = false;
2868 bool fp_operation = false;
2869 bool honor_trapv = false;
2870 tree t;
2871 size_t i;
2872 bool handled, ret;
2873
2874 if (TREE_CODE_CLASS (code) == tcc_comparison
2875 || TREE_CODE_CLASS (code) == tcc_unary
2876 || TREE_CODE_CLASS (code) == tcc_binary)
2877 {
2878 if (TREE_CODE_CLASS (code) == tcc_comparison)
2879 t = TREE_TYPE (gimple_assign_rhs1 (stmt));
2880 else
2881 t = TREE_TYPE (gimple_assign_lhs (stmt));
2882 fp_operation = FLOAT_TYPE_P (t);
2883 if (fp_operation)
2884 {
2885 honor_nans = flag_trapping_math && !flag_finite_math_only;
2886 honor_snans = flag_signaling_nans != 0;
2887 }
2888 else if (INTEGRAL_TYPE_P (t) && TYPE_OVERFLOW_TRAPS (t))
2889 honor_trapv = true;
2890 }
2891
2892 /* First check the LHS. */
2893 if (tree_could_trap_p (gimple_assign_lhs (stmt)))
2894 return true;
2895
2896 /* Check if the main expression may trap. */
2897 ret = operation_could_trap_helper_p (code, fp_operation, honor_trapv,
2898 honor_nans, honor_snans,
2899 gimple_assign_rhs2 (stmt),
2900 &handled);
2901 if (handled)
2902 return ret;
2903
2904 /* If the expression does not trap, see if any of the individual operands may
2905 trap. */
2906 for (i = 1; i < gimple_num_ops (stmt); i++)
2907 if (tree_could_trap_p (gimple_op (stmt, i)))
2908 return true;
2909
2910 return false;
2911 }
2912
2913
2914 /* Return true if statement STMT within FUN could throw an exception. */
2915
2916 bool
stmt_could_throw_p(function * fun,gimple * stmt)2917 stmt_could_throw_p (function *fun, gimple *stmt)
2918 {
2919 if (!flag_exceptions)
2920 return false;
2921
2922 /* The only statements that can throw an exception are assignments,
2923 conditionals, calls, resx, and asms. */
2924 switch (gimple_code (stmt))
2925 {
2926 case GIMPLE_RESX:
2927 return true;
2928
2929 case GIMPLE_CALL:
2930 return !gimple_call_nothrow_p (as_a <gcall *> (stmt));
2931
2932 case GIMPLE_COND:
2933 {
2934 if (fun && !fun->can_throw_non_call_exceptions)
2935 return false;
2936 gcond *cond = as_a <gcond *> (stmt);
2937 tree lhs = gimple_cond_lhs (cond);
2938 return operation_could_trap_p (gimple_cond_code (cond),
2939 FLOAT_TYPE_P (TREE_TYPE (lhs)),
2940 false, NULL_TREE);
2941 }
2942
2943 case GIMPLE_ASSIGN:
2944 if ((fun && !fun->can_throw_non_call_exceptions)
2945 || gimple_clobber_p (stmt))
2946 return false;
2947 return stmt_could_throw_1_p (as_a <gassign *> (stmt));
2948
2949 case GIMPLE_ASM:
2950 if (fun && !fun->can_throw_non_call_exceptions)
2951 return false;
2952 return gimple_asm_volatile_p (as_a <gasm *> (stmt));
2953
2954 default:
2955 return false;
2956 }
2957 }
2958
2959 /* Return true if STMT in function FUN must be assumed necessary because of
2960 non-call exceptions. */
2961
2962 bool
stmt_unremovable_because_of_non_call_eh_p(function * fun,gimple * stmt)2963 stmt_unremovable_because_of_non_call_eh_p (function *fun, gimple *stmt)
2964 {
2965 return (fun->can_throw_non_call_exceptions
2966 && !fun->can_delete_dead_exceptions
2967 && stmt_could_throw_p (fun, stmt));
2968 }
2969
2970 /* Return true if expression T could throw an exception. */
2971
2972 bool
tree_could_throw_p(tree t)2973 tree_could_throw_p (tree t)
2974 {
2975 if (!flag_exceptions)
2976 return false;
2977 if (TREE_CODE (t) == MODIFY_EXPR)
2978 {
2979 if (cfun->can_throw_non_call_exceptions
2980 && tree_could_trap_p (TREE_OPERAND (t, 0)))
2981 return true;
2982 t = TREE_OPERAND (t, 1);
2983 }
2984
2985 if (TREE_CODE (t) == WITH_SIZE_EXPR)
2986 t = TREE_OPERAND (t, 0);
2987 if (TREE_CODE (t) == CALL_EXPR)
2988 return (call_expr_flags (t) & ECF_NOTHROW) == 0;
2989 if (cfun->can_throw_non_call_exceptions)
2990 return tree_could_trap_p (t);
2991 return false;
2992 }
2993
2994 /* Return true if STMT can throw an exception that is not caught within its
2995 function FUN. FUN can be NULL but the function is extra conservative
2996 then. */
2997
2998 bool
stmt_can_throw_external(function * fun,gimple * stmt)2999 stmt_can_throw_external (function *fun, gimple *stmt)
3000 {
3001 int lp_nr;
3002
3003 if (!stmt_could_throw_p (fun, stmt))
3004 return false;
3005 if (!fun)
3006 return true;
3007
3008 lp_nr = lookup_stmt_eh_lp_fn (fun, stmt);
3009 return lp_nr == 0;
3010 }
3011
3012 /* Return true if STMT can throw an exception that is caught within its
3013 function FUN. */
3014
3015 bool
stmt_can_throw_internal(function * fun,gimple * stmt)3016 stmt_can_throw_internal (function *fun, gimple *stmt)
3017 {
3018 int lp_nr;
3019
3020 gcc_checking_assert (fun);
3021 if (!stmt_could_throw_p (fun, stmt))
3022 return false;
3023
3024 lp_nr = lookup_stmt_eh_lp_fn (fun, stmt);
3025 return lp_nr > 0;
3026 }
3027
3028 /* Given a statement STMT in IFUN, if STMT can no longer throw, then
3029 remove any entry it might have from the EH table. Return true if
3030 any change was made. */
3031
3032 bool
maybe_clean_eh_stmt_fn(struct function * ifun,gimple * stmt)3033 maybe_clean_eh_stmt_fn (struct function *ifun, gimple *stmt)
3034 {
3035 if (stmt_could_throw_p (ifun, stmt))
3036 return false;
3037 return remove_stmt_from_eh_lp_fn (ifun, stmt);
3038 }
3039
3040 /* Likewise, but always use the current function. */
3041
3042 bool
maybe_clean_eh_stmt(gimple * stmt)3043 maybe_clean_eh_stmt (gimple *stmt)
3044 {
3045 return maybe_clean_eh_stmt_fn (cfun, stmt);
3046 }
3047
3048 /* Given a statement OLD_STMT and a new statement NEW_STMT that has replaced
3049 OLD_STMT in the function, remove OLD_STMT from the EH table and put NEW_STMT
3050 in the table if it should be in there. Return TRUE if a replacement was
3051 done that my require an EH edge purge. */
3052
3053 bool
maybe_clean_or_replace_eh_stmt(gimple * old_stmt,gimple * new_stmt)3054 maybe_clean_or_replace_eh_stmt (gimple *old_stmt, gimple *new_stmt)
3055 {
3056 int lp_nr = lookup_stmt_eh_lp (old_stmt);
3057
3058 if (lp_nr != 0)
3059 {
3060 bool new_stmt_could_throw = stmt_could_throw_p (cfun, new_stmt);
3061
3062 if (new_stmt == old_stmt && new_stmt_could_throw)
3063 return false;
3064
3065 remove_stmt_from_eh_lp (old_stmt);
3066 if (new_stmt_could_throw)
3067 {
3068 add_stmt_to_eh_lp (new_stmt, lp_nr);
3069 return false;
3070 }
3071 else
3072 return true;
3073 }
3074
3075 return false;
3076 }
3077
3078 /* Given a statement OLD_STMT in OLD_FUN and a duplicate statement NEW_STMT
3079 in NEW_FUN, copy the EH table data from OLD_STMT to NEW_STMT. The MAP
3080 operand is the return value of duplicate_eh_regions. */
3081
3082 bool
maybe_duplicate_eh_stmt_fn(struct function * new_fun,gimple * new_stmt,struct function * old_fun,gimple * old_stmt,hash_map<void *,void * > * map,int default_lp_nr)3083 maybe_duplicate_eh_stmt_fn (struct function *new_fun, gimple *new_stmt,
3084 struct function *old_fun, gimple *old_stmt,
3085 hash_map<void *, void *> *map,
3086 int default_lp_nr)
3087 {
3088 int old_lp_nr, new_lp_nr;
3089
3090 if (!stmt_could_throw_p (new_fun, new_stmt))
3091 return false;
3092
3093 old_lp_nr = lookup_stmt_eh_lp_fn (old_fun, old_stmt);
3094 if (old_lp_nr == 0)
3095 {
3096 if (default_lp_nr == 0)
3097 return false;
3098 new_lp_nr = default_lp_nr;
3099 }
3100 else if (old_lp_nr > 0)
3101 {
3102 eh_landing_pad old_lp, new_lp;
3103
3104 old_lp = (*old_fun->eh->lp_array)[old_lp_nr];
3105 new_lp = static_cast<eh_landing_pad> (*map->get (old_lp));
3106 new_lp_nr = new_lp->index;
3107 }
3108 else
3109 {
3110 eh_region old_r, new_r;
3111
3112 old_r = (*old_fun->eh->region_array)[-old_lp_nr];
3113 new_r = static_cast<eh_region> (*map->get (old_r));
3114 new_lp_nr = -new_r->index;
3115 }
3116
3117 add_stmt_to_eh_lp_fn (new_fun, new_stmt, new_lp_nr);
3118 return true;
3119 }
3120
3121 /* Similar, but both OLD_STMT and NEW_STMT are within the current function,
3122 and thus no remapping is required. */
3123
3124 bool
maybe_duplicate_eh_stmt(gimple * new_stmt,gimple * old_stmt)3125 maybe_duplicate_eh_stmt (gimple *new_stmt, gimple *old_stmt)
3126 {
3127 int lp_nr;
3128
3129 if (!stmt_could_throw_p (cfun, new_stmt))
3130 return false;
3131
3132 lp_nr = lookup_stmt_eh_lp (old_stmt);
3133 if (lp_nr == 0)
3134 return false;
3135
3136 add_stmt_to_eh_lp (new_stmt, lp_nr);
3137 return true;
3138 }
3139
3140 /* Returns TRUE if oneh and twoh are exception handlers (gimple_try_cleanup of
3141 GIMPLE_TRY) that are similar enough to be considered the same. Currently
3142 this only handles handlers consisting of a single call, as that's the
3143 important case for C++: a destructor call for a particular object showing
3144 up in multiple handlers. */
3145
3146 static bool
same_handler_p(gimple_seq oneh,gimple_seq twoh)3147 same_handler_p (gimple_seq oneh, gimple_seq twoh)
3148 {
3149 gimple_stmt_iterator gsi;
3150 gimple *ones, *twos;
3151 unsigned int ai;
3152
3153 gsi = gsi_start (oneh);
3154 if (!gsi_one_before_end_p (gsi))
3155 return false;
3156 ones = gsi_stmt (gsi);
3157
3158 gsi = gsi_start (twoh);
3159 if (!gsi_one_before_end_p (gsi))
3160 return false;
3161 twos = gsi_stmt (gsi);
3162
3163 if (!is_gimple_call (ones)
3164 || !is_gimple_call (twos)
3165 || gimple_call_lhs (ones)
3166 || gimple_call_lhs (twos)
3167 || gimple_call_chain (ones)
3168 || gimple_call_chain (twos)
3169 || !gimple_call_same_target_p (ones, twos)
3170 || gimple_call_num_args (ones) != gimple_call_num_args (twos))
3171 return false;
3172
3173 for (ai = 0; ai < gimple_call_num_args (ones); ++ai)
3174 if (!operand_equal_p (gimple_call_arg (ones, ai),
3175 gimple_call_arg (twos, ai), 0))
3176 return false;
3177
3178 return true;
3179 }
3180
3181 /* Optimize
3182 try { A() } finally { try { ~B() } catch { ~A() } }
3183 try { ... } finally { ~A() }
3184 into
3185 try { A() } catch { ~B() }
3186 try { ~B() ... } finally { ~A() }
3187
3188 This occurs frequently in C++, where A is a local variable and B is a
3189 temporary used in the initializer for A. */
3190
3191 static void
optimize_double_finally(gtry * one,gtry * two)3192 optimize_double_finally (gtry *one, gtry *two)
3193 {
3194 gimple *oneh;
3195 gimple_stmt_iterator gsi;
3196 gimple_seq cleanup;
3197
3198 cleanup = gimple_try_cleanup (one);
3199 gsi = gsi_start (cleanup);
3200 if (!gsi_one_before_end_p (gsi))
3201 return;
3202
3203 oneh = gsi_stmt (gsi);
3204 if (gimple_code (oneh) != GIMPLE_TRY
3205 || gimple_try_kind (oneh) != GIMPLE_TRY_CATCH)
3206 return;
3207
3208 if (same_handler_p (gimple_try_cleanup (oneh), gimple_try_cleanup (two)))
3209 {
3210 gimple_seq seq = gimple_try_eval (oneh);
3211
3212 gimple_try_set_cleanup (one, seq);
3213 gimple_try_set_kind (one, GIMPLE_TRY_CATCH);
3214 seq = copy_gimple_seq_and_replace_locals (seq);
3215 gimple_seq_add_seq (&seq, gimple_try_eval (two));
3216 gimple_try_set_eval (two, seq);
3217 }
3218 }
3219
3220 /* Perform EH refactoring optimizations that are simpler to do when code
3221 flow has been lowered but EH structures haven't. */
3222
3223 static void
refactor_eh_r(gimple_seq seq)3224 refactor_eh_r (gimple_seq seq)
3225 {
3226 gimple_stmt_iterator gsi;
3227 gimple *one, *two;
3228
3229 one = NULL;
3230 two = NULL;
3231 gsi = gsi_start (seq);
3232 while (1)
3233 {
3234 one = two;
3235 if (gsi_end_p (gsi))
3236 two = NULL;
3237 else
3238 two = gsi_stmt (gsi);
3239 if (one && two)
3240 if (gtry *try_one = dyn_cast <gtry *> (one))
3241 if (gtry *try_two = dyn_cast <gtry *> (two))
3242 if (gimple_try_kind (try_one) == GIMPLE_TRY_FINALLY
3243 && gimple_try_kind (try_two) == GIMPLE_TRY_FINALLY)
3244 optimize_double_finally (try_one, try_two);
3245 if (one)
3246 switch (gimple_code (one))
3247 {
3248 case GIMPLE_TRY:
3249 refactor_eh_r (gimple_try_eval (one));
3250 refactor_eh_r (gimple_try_cleanup (one));
3251 break;
3252 case GIMPLE_CATCH:
3253 refactor_eh_r (gimple_catch_handler (as_a <gcatch *> (one)));
3254 break;
3255 case GIMPLE_EH_FILTER:
3256 refactor_eh_r (gimple_eh_filter_failure (one));
3257 break;
3258 case GIMPLE_EH_ELSE:
3259 {
3260 geh_else *eh_else_stmt = as_a <geh_else *> (one);
3261 refactor_eh_r (gimple_eh_else_n_body (eh_else_stmt));
3262 refactor_eh_r (gimple_eh_else_e_body (eh_else_stmt));
3263 }
3264 break;
3265 default:
3266 break;
3267 }
3268 if (two)
3269 gsi_next (&gsi);
3270 else
3271 break;
3272 }
3273 }
3274
3275 namespace {
3276
3277 const pass_data pass_data_refactor_eh =
3278 {
3279 GIMPLE_PASS, /* type */
3280 "ehopt", /* name */
3281 OPTGROUP_NONE, /* optinfo_flags */
3282 TV_TREE_EH, /* tv_id */
3283 PROP_gimple_lcf, /* properties_required */
3284 0, /* properties_provided */
3285 0, /* properties_destroyed */
3286 0, /* todo_flags_start */
3287 0, /* todo_flags_finish */
3288 };
3289
3290 class pass_refactor_eh : public gimple_opt_pass
3291 {
3292 public:
pass_refactor_eh(gcc::context * ctxt)3293 pass_refactor_eh (gcc::context *ctxt)
3294 : gimple_opt_pass (pass_data_refactor_eh, ctxt)
3295 {}
3296
3297 /* opt_pass methods: */
gate(function *)3298 virtual bool gate (function *) { return flag_exceptions != 0; }
execute(function *)3299 virtual unsigned int execute (function *)
3300 {
3301 refactor_eh_r (gimple_body (current_function_decl));
3302 return 0;
3303 }
3304
3305 }; // class pass_refactor_eh
3306
3307 } // anon namespace
3308
3309 gimple_opt_pass *
make_pass_refactor_eh(gcc::context * ctxt)3310 make_pass_refactor_eh (gcc::context *ctxt)
3311 {
3312 return new pass_refactor_eh (ctxt);
3313 }
3314
3315 /* At the end of gimple optimization, we can lower RESX. */
3316
3317 static bool
lower_resx(basic_block bb,gresx * stmt,hash_map<eh_region,tree> * mnt_map)3318 lower_resx (basic_block bb, gresx *stmt,
3319 hash_map<eh_region, tree> *mnt_map)
3320 {
3321 int lp_nr;
3322 eh_region src_r, dst_r;
3323 gimple_stmt_iterator gsi;
3324 gimple *x;
3325 tree fn, src_nr;
3326 bool ret = false;
3327
3328 lp_nr = lookup_stmt_eh_lp (stmt);
3329 if (lp_nr != 0)
3330 dst_r = get_eh_region_from_lp_number (lp_nr);
3331 else
3332 dst_r = NULL;
3333
3334 src_r = get_eh_region_from_number (gimple_resx_region (stmt));
3335 gsi = gsi_last_bb (bb);
3336
3337 if (src_r == NULL)
3338 {
3339 /* We can wind up with no source region when pass_cleanup_eh shows
3340 that there are no entries into an eh region and deletes it, but
3341 then the block that contains the resx isn't removed. This can
3342 happen without optimization when the switch statement created by
3343 lower_try_finally_switch isn't simplified to remove the eh case.
3344
3345 Resolve this by expanding the resx node to an abort. */
3346
3347 fn = builtin_decl_implicit (BUILT_IN_TRAP);
3348 x = gimple_build_call (fn, 0);
3349 gsi_insert_before (&gsi, x, GSI_SAME_STMT);
3350
3351 while (EDGE_COUNT (bb->succs) > 0)
3352 remove_edge (EDGE_SUCC (bb, 0));
3353 }
3354 else if (dst_r)
3355 {
3356 /* When we have a destination region, we resolve this by copying
3357 the excptr and filter values into place, and changing the edge
3358 to immediately after the landing pad. */
3359 edge e;
3360
3361 if (lp_nr < 0)
3362 {
3363 basic_block new_bb;
3364 tree lab;
3365
3366 /* We are resuming into a MUST_NOT_CALL region. Expand a call to
3367 the failure decl into a new block, if needed. */
3368 gcc_assert (dst_r->type == ERT_MUST_NOT_THROW);
3369
3370 tree *slot = mnt_map->get (dst_r);
3371 if (slot == NULL)
3372 {
3373 gimple_stmt_iterator gsi2;
3374
3375 new_bb = create_empty_bb (bb);
3376 new_bb->count = bb->count;
3377 add_bb_to_loop (new_bb, bb->loop_father);
3378 lab = gimple_block_label (new_bb);
3379 gsi2 = gsi_start_bb (new_bb);
3380
3381 fn = dst_r->u.must_not_throw.failure_decl;
3382 x = gimple_build_call (fn, 0);
3383 gimple_set_location (x, dst_r->u.must_not_throw.failure_loc);
3384 gsi_insert_after (&gsi2, x, GSI_CONTINUE_LINKING);
3385
3386 mnt_map->put (dst_r, lab);
3387 }
3388 else
3389 {
3390 lab = *slot;
3391 new_bb = label_to_block (cfun, lab);
3392 }
3393
3394 gcc_assert (EDGE_COUNT (bb->succs) == 0);
3395 e = make_single_succ_edge (bb, new_bb, EDGE_FALLTHRU);
3396 }
3397 else
3398 {
3399 edge_iterator ei;
3400 tree dst_nr = build_int_cst (integer_type_node, dst_r->index);
3401
3402 fn = builtin_decl_implicit (BUILT_IN_EH_COPY_VALUES);
3403 src_nr = build_int_cst (integer_type_node, src_r->index);
3404 x = gimple_build_call (fn, 2, dst_nr, src_nr);
3405 gsi_insert_before (&gsi, x, GSI_SAME_STMT);
3406
3407 /* Update the flags for the outgoing edge. */
3408 e = single_succ_edge (bb);
3409 gcc_assert (e->flags & EDGE_EH);
3410 e->flags = (e->flags & ~EDGE_EH) | EDGE_FALLTHRU;
3411 e->probability = profile_probability::always ();
3412
3413 /* If there are no more EH users of the landing pad, delete it. */
3414 FOR_EACH_EDGE (e, ei, e->dest->preds)
3415 if (e->flags & EDGE_EH)
3416 break;
3417 if (e == NULL)
3418 {
3419 eh_landing_pad lp = get_eh_landing_pad_from_number (lp_nr);
3420 remove_eh_landing_pad (lp);
3421 }
3422 }
3423
3424 ret = true;
3425 }
3426 else
3427 {
3428 tree var;
3429
3430 /* When we don't have a destination region, this exception escapes
3431 up the call chain. We resolve this by generating a call to the
3432 _Unwind_Resume library function. */
3433
3434 /* The ARM EABI redefines _Unwind_Resume as __cxa_end_cleanup
3435 with no arguments for C++. Check for that. */
3436 if (src_r->use_cxa_end_cleanup)
3437 {
3438 fn = builtin_decl_implicit (BUILT_IN_CXA_END_CLEANUP);
3439 x = gimple_build_call (fn, 0);
3440 gsi_insert_before (&gsi, x, GSI_SAME_STMT);
3441 }
3442 else
3443 {
3444 fn = builtin_decl_implicit (BUILT_IN_EH_POINTER);
3445 src_nr = build_int_cst (integer_type_node, src_r->index);
3446 x = gimple_build_call (fn, 1, src_nr);
3447 var = create_tmp_var (ptr_type_node);
3448 var = make_ssa_name (var, x);
3449 gimple_call_set_lhs (x, var);
3450 gsi_insert_before (&gsi, x, GSI_SAME_STMT);
3451
3452 /* When exception handling is delegated to a caller function, we
3453 have to guarantee that shadow memory variables living on stack
3454 will be cleaner before control is given to a parent function. */
3455 if (sanitize_flags_p (SANITIZE_ADDRESS))
3456 {
3457 tree decl
3458 = builtin_decl_implicit (BUILT_IN_ASAN_HANDLE_NO_RETURN);
3459 gimple *g = gimple_build_call (decl, 0);
3460 gimple_set_location (g, gimple_location (stmt));
3461 gsi_insert_before (&gsi, g, GSI_SAME_STMT);
3462 }
3463
3464 fn = builtin_decl_implicit (BUILT_IN_UNWIND_RESUME);
3465 x = gimple_build_call (fn, 1, var);
3466 gsi_insert_before (&gsi, x, GSI_SAME_STMT);
3467 }
3468
3469 gcc_assert (EDGE_COUNT (bb->succs) == 0);
3470 }
3471
3472 gsi_remove (&gsi, true);
3473
3474 return ret;
3475 }
3476
3477 namespace {
3478
3479 const pass_data pass_data_lower_resx =
3480 {
3481 GIMPLE_PASS, /* type */
3482 "resx", /* name */
3483 OPTGROUP_NONE, /* optinfo_flags */
3484 TV_TREE_EH, /* tv_id */
3485 PROP_gimple_lcf, /* properties_required */
3486 0, /* properties_provided */
3487 0, /* properties_destroyed */
3488 0, /* todo_flags_start */
3489 0, /* todo_flags_finish */
3490 };
3491
3492 class pass_lower_resx : public gimple_opt_pass
3493 {
3494 public:
pass_lower_resx(gcc::context * ctxt)3495 pass_lower_resx (gcc::context *ctxt)
3496 : gimple_opt_pass (pass_data_lower_resx, ctxt)
3497 {}
3498
3499 /* opt_pass methods: */
gate(function *)3500 virtual bool gate (function *) { return flag_exceptions != 0; }
3501 virtual unsigned int execute (function *);
3502
3503 }; // class pass_lower_resx
3504
3505 unsigned
execute(function * fun)3506 pass_lower_resx::execute (function *fun)
3507 {
3508 basic_block bb;
3509 bool dominance_invalidated = false;
3510 bool any_rewritten = false;
3511
3512 hash_map<eh_region, tree> mnt_map;
3513
3514 FOR_EACH_BB_FN (bb, fun)
3515 {
3516 gimple *last = last_stmt (bb);
3517 if (last && is_gimple_resx (last))
3518 {
3519 dominance_invalidated |=
3520 lower_resx (bb, as_a <gresx *> (last), &mnt_map);
3521 any_rewritten = true;
3522 }
3523 }
3524
3525 if (dominance_invalidated)
3526 {
3527 free_dominance_info (CDI_DOMINATORS);
3528 free_dominance_info (CDI_POST_DOMINATORS);
3529 }
3530
3531 return any_rewritten ? TODO_update_ssa_only_virtuals : 0;
3532 }
3533
3534 } // anon namespace
3535
3536 gimple_opt_pass *
make_pass_lower_resx(gcc::context * ctxt)3537 make_pass_lower_resx (gcc::context *ctxt)
3538 {
3539 return new pass_lower_resx (ctxt);
3540 }
3541
3542 /* Try to optimize var = {v} {CLOBBER} stmts followed just by
3543 external throw. */
3544
3545 static void
optimize_clobbers(basic_block bb)3546 optimize_clobbers (basic_block bb)
3547 {
3548 gimple_stmt_iterator gsi = gsi_last_bb (bb);
3549 bool any_clobbers = false;
3550 bool seen_stack_restore = false;
3551 edge_iterator ei;
3552 edge e;
3553
3554 /* Only optimize anything if the bb contains at least one clobber,
3555 ends with resx (checked by caller), optionally contains some
3556 debug stmts or labels, or at most one __builtin_stack_restore
3557 call, and has an incoming EH edge. */
3558 for (gsi_prev (&gsi); !gsi_end_p (gsi); gsi_prev (&gsi))
3559 {
3560 gimple *stmt = gsi_stmt (gsi);
3561 if (is_gimple_debug (stmt))
3562 continue;
3563 if (gimple_clobber_p (stmt))
3564 {
3565 any_clobbers = true;
3566 continue;
3567 }
3568 if (!seen_stack_restore
3569 && gimple_call_builtin_p (stmt, BUILT_IN_STACK_RESTORE))
3570 {
3571 seen_stack_restore = true;
3572 continue;
3573 }
3574 if (gimple_code (stmt) == GIMPLE_LABEL)
3575 break;
3576 return;
3577 }
3578 if (!any_clobbers)
3579 return;
3580 FOR_EACH_EDGE (e, ei, bb->preds)
3581 if (e->flags & EDGE_EH)
3582 break;
3583 if (e == NULL)
3584 return;
3585 gsi = gsi_last_bb (bb);
3586 for (gsi_prev (&gsi); !gsi_end_p (gsi); gsi_prev (&gsi))
3587 {
3588 gimple *stmt = gsi_stmt (gsi);
3589 if (!gimple_clobber_p (stmt))
3590 continue;
3591 unlink_stmt_vdef (stmt);
3592 gsi_remove (&gsi, true);
3593 release_defs (stmt);
3594 }
3595 }
3596
3597 /* Try to sink var = {v} {CLOBBER} stmts followed just by
3598 internal throw to successor BB.
3599 SUNK, if not NULL, is an array of sequences indexed by basic-block
3600 index to sink to and to pick up sinking opportunities from.
3601 If FOUND_OPPORTUNITY is not NULL then do not perform the optimization
3602 but set *FOUND_OPPORTUNITY to true. */
3603
3604 static int
3605 sink_clobbers (basic_block bb,
3606 gimple_seq *sunk = NULL, bool *found_opportunity = NULL)
3607 {
3608 edge e;
3609 edge_iterator ei;
3610 gimple_stmt_iterator gsi, dgsi;
3611 basic_block succbb;
3612 bool any_clobbers = false;
3613 unsigned todo = 0;
3614
3615 /* Only optimize if BB has a single EH successor and
3616 all predecessor edges are EH too. */
3617 if (!single_succ_p (bb)
3618 || (single_succ_edge (bb)->flags & EDGE_EH) == 0)
3619 return 0;
3620
3621 FOR_EACH_EDGE (e, ei, bb->preds)
3622 {
3623 if ((e->flags & EDGE_EH) == 0)
3624 return 0;
3625 }
3626
3627 /* And BB contains only CLOBBER stmts before the final
3628 RESX. */
3629 gsi = gsi_last_bb (bb);
3630 for (gsi_prev (&gsi); !gsi_end_p (gsi); gsi_prev (&gsi))
3631 {
3632 gimple *stmt = gsi_stmt (gsi);
3633 if (is_gimple_debug (stmt))
3634 continue;
3635 if (gimple_code (stmt) == GIMPLE_LABEL)
3636 break;
3637 if (!gimple_clobber_p (stmt))
3638 return 0;
3639 any_clobbers = true;
3640 }
3641 if (!any_clobbers && (!sunk || gimple_seq_empty_p (sunk[bb->index])))
3642 return 0;
3643
3644 /* If this was a dry run, tell it we found clobbers to sink. */
3645 if (found_opportunity)
3646 {
3647 *found_opportunity = true;
3648 return 0;
3649 }
3650
3651 edge succe = single_succ_edge (bb);
3652 succbb = succe->dest;
3653
3654 /* See if there is a virtual PHI node to take an updated virtual
3655 operand from. */
3656 gphi *vphi = NULL;
3657 for (gphi_iterator gpi = gsi_start_phis (succbb);
3658 !gsi_end_p (gpi); gsi_next (&gpi))
3659 {
3660 tree res = gimple_phi_result (gpi.phi ());
3661 if (virtual_operand_p (res))
3662 {
3663 vphi = gpi.phi ();
3664 break;
3665 }
3666 }
3667
3668 gimple *first_sunk = NULL;
3669 gimple *last_sunk = NULL;
3670 if (sunk && !(succbb->flags & BB_VISITED))
3671 dgsi = gsi_start (sunk[succbb->index]);
3672 else
3673 dgsi = gsi_after_labels (succbb);
3674 gsi = gsi_last_bb (bb);
3675 for (gsi_prev (&gsi); !gsi_end_p (gsi); gsi_prev (&gsi))
3676 {
3677 gimple *stmt = gsi_stmt (gsi);
3678 tree lhs;
3679 if (is_gimple_debug (stmt))
3680 continue;
3681 if (gimple_code (stmt) == GIMPLE_LABEL)
3682 break;
3683 lhs = gimple_assign_lhs (stmt);
3684 /* Unfortunately we don't have dominance info updated at this
3685 point, so checking if
3686 dominated_by_p (CDI_DOMINATORS, succbb,
3687 gimple_bb (SSA_NAME_DEF_STMT (TREE_OPERAND (lhs, 0)))
3688 would be too costly. Thus, avoid sinking any clobbers that
3689 refer to non-(D) SSA_NAMEs. */
3690 if (TREE_CODE (lhs) == MEM_REF
3691 && TREE_CODE (TREE_OPERAND (lhs, 0)) == SSA_NAME
3692 && !SSA_NAME_IS_DEFAULT_DEF (TREE_OPERAND (lhs, 0)))
3693 {
3694 unlink_stmt_vdef (stmt);
3695 gsi_remove (&gsi, true);
3696 release_defs (stmt);
3697 continue;
3698 }
3699
3700 /* As we do not change stmt order when sinking across a
3701 forwarder edge we can keep virtual operands in place. */
3702 gsi_remove (&gsi, false);
3703 gsi_insert_before (&dgsi, stmt, GSI_NEW_STMT);
3704 if (!first_sunk)
3705 first_sunk = stmt;
3706 last_sunk = stmt;
3707 }
3708 if (sunk && !gimple_seq_empty_p (sunk[bb->index]))
3709 {
3710 if (!first_sunk)
3711 first_sunk = gsi_stmt (gsi_last (sunk[bb->index]));
3712 last_sunk = gsi_stmt (gsi_start (sunk[bb->index]));
3713 gsi_insert_seq_before_without_update (&dgsi,
3714 sunk[bb->index], GSI_NEW_STMT);
3715 sunk[bb->index] = NULL;
3716 }
3717 if (first_sunk)
3718 {
3719 /* Adjust virtual operands if we sunk across a virtual PHI. */
3720 if (vphi)
3721 {
3722 imm_use_iterator iter;
3723 use_operand_p use_p;
3724 gimple *use_stmt;
3725 tree phi_def = gimple_phi_result (vphi);
3726 FOR_EACH_IMM_USE_STMT (use_stmt, iter, phi_def)
3727 FOR_EACH_IMM_USE_ON_STMT (use_p, iter)
3728 SET_USE (use_p, gimple_vdef (first_sunk));
3729 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (phi_def))
3730 {
3731 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (gimple_vdef (first_sunk)) = 1;
3732 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (phi_def) = 0;
3733 }
3734 SET_USE (PHI_ARG_DEF_PTR_FROM_EDGE (vphi, succe),
3735 gimple_vuse (last_sunk));
3736 SET_USE (gimple_vuse_op (last_sunk), phi_def);
3737 }
3738 /* If there isn't a single predecessor but no virtual PHI node
3739 arrange for virtual operands to be renamed. */
3740 else if (!single_pred_p (succbb)
3741 && TREE_CODE (gimple_vuse (last_sunk)) == SSA_NAME)
3742 {
3743 mark_virtual_operand_for_renaming (gimple_vuse (last_sunk));
3744 todo |= TODO_update_ssa_only_virtuals;
3745 }
3746 }
3747
3748 return todo;
3749 }
3750
3751 /* At the end of inlining, we can lower EH_DISPATCH. Return true when
3752 we have found some duplicate labels and removed some edges. */
3753
3754 static bool
lower_eh_dispatch(basic_block src,geh_dispatch * stmt)3755 lower_eh_dispatch (basic_block src, geh_dispatch *stmt)
3756 {
3757 gimple_stmt_iterator gsi;
3758 int region_nr;
3759 eh_region r;
3760 tree filter, fn;
3761 gimple *x;
3762 bool redirected = false;
3763
3764 region_nr = gimple_eh_dispatch_region (stmt);
3765 r = get_eh_region_from_number (region_nr);
3766
3767 gsi = gsi_last_bb (src);
3768
3769 switch (r->type)
3770 {
3771 case ERT_TRY:
3772 {
3773 auto_vec<tree> labels;
3774 tree default_label = NULL;
3775 eh_catch c;
3776 edge_iterator ei;
3777 edge e;
3778 hash_set<tree> seen_values;
3779
3780 /* Collect the labels for a switch. Zero the post_landing_pad
3781 field becase we'll no longer have anything keeping these labels
3782 in existence and the optimizer will be free to merge these
3783 blocks at will. */
3784 for (c = r->u.eh_try.first_catch; c ; c = c->next_catch)
3785 {
3786 tree tp_node, flt_node, lab = c->label;
3787 bool have_label = false;
3788
3789 c->label = NULL;
3790 tp_node = c->type_list;
3791 flt_node = c->filter_list;
3792
3793 if (tp_node == NULL)
3794 {
3795 default_label = lab;
3796 break;
3797 }
3798 do
3799 {
3800 /* Filter out duplicate labels that arise when this handler
3801 is shadowed by an earlier one. When no labels are
3802 attached to the handler anymore, we remove
3803 the corresponding edge and then we delete unreachable
3804 blocks at the end of this pass. */
3805 if (! seen_values.contains (TREE_VALUE (flt_node)))
3806 {
3807 tree t = build_case_label (TREE_VALUE (flt_node),
3808 NULL, lab);
3809 labels.safe_push (t);
3810 seen_values.add (TREE_VALUE (flt_node));
3811 have_label = true;
3812 }
3813
3814 tp_node = TREE_CHAIN (tp_node);
3815 flt_node = TREE_CHAIN (flt_node);
3816 }
3817 while (tp_node);
3818 if (! have_label)
3819 {
3820 remove_edge (find_edge (src, label_to_block (cfun, lab)));
3821 redirected = true;
3822 }
3823 }
3824
3825 /* Clean up the edge flags. */
3826 FOR_EACH_EDGE (e, ei, src->succs)
3827 {
3828 if (e->flags & EDGE_FALLTHRU)
3829 {
3830 /* If there was no catch-all, use the fallthru edge. */
3831 if (default_label == NULL)
3832 default_label = gimple_block_label (e->dest);
3833 e->flags &= ~EDGE_FALLTHRU;
3834 }
3835 }
3836 gcc_assert (default_label != NULL);
3837
3838 /* Don't generate a switch if there's only a default case.
3839 This is common in the form of try { A; } catch (...) { B; }. */
3840 if (!labels.exists ())
3841 {
3842 e = single_succ_edge (src);
3843 e->flags |= EDGE_FALLTHRU;
3844 }
3845 else
3846 {
3847 fn = builtin_decl_implicit (BUILT_IN_EH_FILTER);
3848 x = gimple_build_call (fn, 1, build_int_cst (integer_type_node,
3849 region_nr));
3850 filter = create_tmp_var (TREE_TYPE (TREE_TYPE (fn)));
3851 filter = make_ssa_name (filter, x);
3852 gimple_call_set_lhs (x, filter);
3853 gimple_set_location (x, gimple_location (stmt));
3854 gsi_insert_before (&gsi, x, GSI_SAME_STMT);
3855
3856 /* Turn the default label into a default case. */
3857 default_label = build_case_label (NULL, NULL, default_label);
3858 sort_case_labels (labels);
3859
3860 x = gimple_build_switch (filter, default_label, labels);
3861 gimple_set_location (x, gimple_location (stmt));
3862 gsi_insert_before (&gsi, x, GSI_SAME_STMT);
3863 }
3864 }
3865 break;
3866
3867 case ERT_ALLOWED_EXCEPTIONS:
3868 {
3869 edge b_e = BRANCH_EDGE (src);
3870 edge f_e = FALLTHRU_EDGE (src);
3871
3872 fn = builtin_decl_implicit (BUILT_IN_EH_FILTER);
3873 x = gimple_build_call (fn, 1, build_int_cst (integer_type_node,
3874 region_nr));
3875 filter = create_tmp_var (TREE_TYPE (TREE_TYPE (fn)));
3876 filter = make_ssa_name (filter, x);
3877 gimple_call_set_lhs (x, filter);
3878 gimple_set_location (x, gimple_location (stmt));
3879 gsi_insert_before (&gsi, x, GSI_SAME_STMT);
3880
3881 r->u.allowed.label = NULL;
3882 x = gimple_build_cond (EQ_EXPR, filter,
3883 build_int_cst (TREE_TYPE (filter),
3884 r->u.allowed.filter),
3885 NULL_TREE, NULL_TREE);
3886 gsi_insert_before (&gsi, x, GSI_SAME_STMT);
3887
3888 b_e->flags = b_e->flags | EDGE_TRUE_VALUE;
3889 f_e->flags = (f_e->flags & ~EDGE_FALLTHRU) | EDGE_FALSE_VALUE;
3890 }
3891 break;
3892
3893 default:
3894 gcc_unreachable ();
3895 }
3896
3897 /* Replace the EH_DISPATCH with the SWITCH or COND generated above. */
3898 gsi_remove (&gsi, true);
3899 return redirected;
3900 }
3901
3902 namespace {
3903
3904 const pass_data pass_data_lower_eh_dispatch =
3905 {
3906 GIMPLE_PASS, /* type */
3907 "ehdisp", /* name */
3908 OPTGROUP_NONE, /* optinfo_flags */
3909 TV_TREE_EH, /* tv_id */
3910 PROP_gimple_lcf, /* properties_required */
3911 0, /* properties_provided */
3912 0, /* properties_destroyed */
3913 0, /* todo_flags_start */
3914 0, /* todo_flags_finish */
3915 };
3916
3917 class pass_lower_eh_dispatch : public gimple_opt_pass
3918 {
3919 public:
pass_lower_eh_dispatch(gcc::context * ctxt)3920 pass_lower_eh_dispatch (gcc::context *ctxt)
3921 : gimple_opt_pass (pass_data_lower_eh_dispatch, ctxt)
3922 {}
3923
3924 /* opt_pass methods: */
gate(function * fun)3925 virtual bool gate (function *fun) { return fun->eh->region_tree != NULL; }
3926 virtual unsigned int execute (function *);
3927
3928 }; // class pass_lower_eh_dispatch
3929
3930 unsigned
execute(function * fun)3931 pass_lower_eh_dispatch::execute (function *fun)
3932 {
3933 basic_block bb;
3934 int flags = 0;
3935 bool redirected = false;
3936 bool any_resx_to_process = false;
3937
3938 assign_filter_values ();
3939
3940 FOR_EACH_BB_FN (bb, fun)
3941 {
3942 gimple *last = last_stmt (bb);
3943 if (last == NULL)
3944 continue;
3945 if (gimple_code (last) == GIMPLE_EH_DISPATCH)
3946 {
3947 redirected |= lower_eh_dispatch (bb,
3948 as_a <geh_dispatch *> (last));
3949 flags |= TODO_update_ssa_only_virtuals;
3950 }
3951 else if (gimple_code (last) == GIMPLE_RESX)
3952 {
3953 if (stmt_can_throw_external (fun, last))
3954 optimize_clobbers (bb);
3955 else if (!any_resx_to_process)
3956 sink_clobbers (bb, NULL, &any_resx_to_process);
3957 }
3958 bb->flags &= ~BB_VISITED;
3959 }
3960 if (redirected)
3961 {
3962 free_dominance_info (CDI_DOMINATORS);
3963 delete_unreachable_blocks ();
3964 }
3965
3966 if (any_resx_to_process)
3967 {
3968 /* Make sure to catch all secondary sinking opportunities by processing
3969 blocks in RPO order and after all CFG modifications from lowering
3970 and unreachable block removal. */
3971 int *rpo = XNEWVEC (int, n_basic_blocks_for_fn (fun));
3972 int rpo_n = pre_and_rev_post_order_compute_fn (fun, NULL, rpo, false);
3973 gimple_seq *sunk = XCNEWVEC (gimple_seq, last_basic_block_for_fn (fun));
3974 for (int i = 0; i < rpo_n; ++i)
3975 {
3976 bb = BASIC_BLOCK_FOR_FN (fun, rpo[i]);
3977 gimple *last = last_stmt (bb);
3978 if (last
3979 && gimple_code (last) == GIMPLE_RESX
3980 && !stmt_can_throw_external (fun, last))
3981 flags |= sink_clobbers (bb, sunk);
3982 /* If there were any clobbers sunk into this BB, insert them now. */
3983 if (!gimple_seq_empty_p (sunk[bb->index]))
3984 {
3985 gimple_stmt_iterator gsi = gsi_after_labels (bb);
3986 gsi_insert_seq_before (&gsi, sunk[bb->index], GSI_NEW_STMT);
3987 sunk[bb->index] = NULL;
3988 }
3989 bb->flags |= BB_VISITED;
3990 }
3991 free (rpo);
3992 free (sunk);
3993 }
3994
3995 return flags;
3996 }
3997
3998 } // anon namespace
3999
4000 gimple_opt_pass *
make_pass_lower_eh_dispatch(gcc::context * ctxt)4001 make_pass_lower_eh_dispatch (gcc::context *ctxt)
4002 {
4003 return new pass_lower_eh_dispatch (ctxt);
4004 }
4005
4006 /* Walk statements, see what regions and, optionally, landing pads
4007 are really referenced.
4008
4009 Returns in R_REACHABLEP an sbitmap with bits set for reachable regions,
4010 and in LP_REACHABLE an sbitmap with bits set for reachable landing pads.
4011
4012 Passing NULL for LP_REACHABLE is valid, in this case only reachable
4013 regions are marked.
4014
4015 The caller is responsible for freeing the returned sbitmaps. */
4016
4017 static void
mark_reachable_handlers(sbitmap * r_reachablep,sbitmap * lp_reachablep)4018 mark_reachable_handlers (sbitmap *r_reachablep, sbitmap *lp_reachablep)
4019 {
4020 sbitmap r_reachable, lp_reachable;
4021 basic_block bb;
4022 bool mark_landing_pads = (lp_reachablep != NULL);
4023 gcc_checking_assert (r_reachablep != NULL);
4024
4025 r_reachable = sbitmap_alloc (cfun->eh->region_array->length ());
4026 bitmap_clear (r_reachable);
4027 *r_reachablep = r_reachable;
4028
4029 if (mark_landing_pads)
4030 {
4031 lp_reachable = sbitmap_alloc (cfun->eh->lp_array->length ());
4032 bitmap_clear (lp_reachable);
4033 *lp_reachablep = lp_reachable;
4034 }
4035 else
4036 lp_reachable = NULL;
4037
4038 FOR_EACH_BB_FN (bb, cfun)
4039 {
4040 gimple_stmt_iterator gsi;
4041
4042 for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
4043 {
4044 gimple *stmt = gsi_stmt (gsi);
4045
4046 if (mark_landing_pads)
4047 {
4048 int lp_nr = lookup_stmt_eh_lp (stmt);
4049
4050 /* Negative LP numbers are MUST_NOT_THROW regions which
4051 are not considered BB enders. */
4052 if (lp_nr < 0)
4053 bitmap_set_bit (r_reachable, -lp_nr);
4054
4055 /* Positive LP numbers are real landing pads, and BB enders. */
4056 else if (lp_nr > 0)
4057 {
4058 gcc_assert (gsi_one_before_end_p (gsi));
4059 eh_region region = get_eh_region_from_lp_number (lp_nr);
4060 bitmap_set_bit (r_reachable, region->index);
4061 bitmap_set_bit (lp_reachable, lp_nr);
4062 }
4063 }
4064
4065 /* Avoid removing regions referenced from RESX/EH_DISPATCH. */
4066 switch (gimple_code (stmt))
4067 {
4068 case GIMPLE_RESX:
4069 bitmap_set_bit (r_reachable,
4070 gimple_resx_region (as_a <gresx *> (stmt)));
4071 break;
4072 case GIMPLE_EH_DISPATCH:
4073 bitmap_set_bit (r_reachable,
4074 gimple_eh_dispatch_region (
4075 as_a <geh_dispatch *> (stmt)));
4076 break;
4077 case GIMPLE_CALL:
4078 if (gimple_call_builtin_p (stmt, BUILT_IN_EH_COPY_VALUES))
4079 for (int i = 0; i < 2; ++i)
4080 {
4081 tree rt = gimple_call_arg (stmt, i);
4082 HOST_WIDE_INT ri = tree_to_shwi (rt);
4083
4084 gcc_assert (ri == (int)ri);
4085 bitmap_set_bit (r_reachable, ri);
4086 }
4087 break;
4088 default:
4089 break;
4090 }
4091 }
4092 }
4093 }
4094
4095 /* Remove unreachable handlers and unreachable landing pads. */
4096
4097 static void
remove_unreachable_handlers(void)4098 remove_unreachable_handlers (void)
4099 {
4100 sbitmap r_reachable, lp_reachable;
4101 eh_region region;
4102 eh_landing_pad lp;
4103 unsigned i;
4104
4105 mark_reachable_handlers (&r_reachable, &lp_reachable);
4106
4107 if (dump_file)
4108 {
4109 fprintf (dump_file, "Before removal of unreachable regions:\n");
4110 dump_eh_tree (dump_file, cfun);
4111 fprintf (dump_file, "Reachable regions: ");
4112 dump_bitmap_file (dump_file, r_reachable);
4113 fprintf (dump_file, "Reachable landing pads: ");
4114 dump_bitmap_file (dump_file, lp_reachable);
4115 }
4116
4117 if (dump_file)
4118 {
4119 FOR_EACH_VEC_SAFE_ELT (cfun->eh->region_array, i, region)
4120 if (region && !bitmap_bit_p (r_reachable, region->index))
4121 fprintf (dump_file,
4122 "Removing unreachable region %d\n",
4123 region->index);
4124 }
4125
4126 remove_unreachable_eh_regions (r_reachable);
4127
4128 FOR_EACH_VEC_SAFE_ELT (cfun->eh->lp_array, i, lp)
4129 if (lp && !bitmap_bit_p (lp_reachable, lp->index))
4130 {
4131 if (dump_file)
4132 fprintf (dump_file,
4133 "Removing unreachable landing pad %d\n",
4134 lp->index);
4135 remove_eh_landing_pad (lp);
4136 }
4137
4138 if (dump_file)
4139 {
4140 fprintf (dump_file, "\n\nAfter removal of unreachable regions:\n");
4141 dump_eh_tree (dump_file, cfun);
4142 fprintf (dump_file, "\n\n");
4143 }
4144
4145 sbitmap_free (r_reachable);
4146 sbitmap_free (lp_reachable);
4147
4148 if (flag_checking)
4149 verify_eh_tree (cfun);
4150 }
4151
4152 /* Remove unreachable handlers if any landing pads have been removed after
4153 last ehcleanup pass (due to gimple_purge_dead_eh_edges). */
4154
4155 void
maybe_remove_unreachable_handlers(void)4156 maybe_remove_unreachable_handlers (void)
4157 {
4158 eh_landing_pad lp;
4159 unsigned i;
4160
4161 if (cfun->eh == NULL)
4162 return;
4163
4164 FOR_EACH_VEC_SAFE_ELT (cfun->eh->lp_array, i, lp)
4165 if (lp
4166 && (lp->post_landing_pad == NULL_TREE
4167 || label_to_block (cfun, lp->post_landing_pad) == NULL))
4168 {
4169 remove_unreachable_handlers ();
4170 return;
4171 }
4172 }
4173
4174 /* Remove regions that do not have landing pads. This assumes
4175 that remove_unreachable_handlers has already been run, and
4176 that we've just manipulated the landing pads since then.
4177
4178 Preserve regions with landing pads and regions that prevent
4179 exceptions from propagating further, even if these regions
4180 are not reachable. */
4181
4182 static void
remove_unreachable_handlers_no_lp(void)4183 remove_unreachable_handlers_no_lp (void)
4184 {
4185 eh_region region;
4186 sbitmap r_reachable;
4187 unsigned i;
4188
4189 mark_reachable_handlers (&r_reachable, /*lp_reachablep=*/NULL);
4190
4191 FOR_EACH_VEC_SAFE_ELT (cfun->eh->region_array, i, region)
4192 {
4193 if (! region)
4194 continue;
4195
4196 if (region->landing_pads != NULL
4197 || region->type == ERT_MUST_NOT_THROW)
4198 bitmap_set_bit (r_reachable, region->index);
4199
4200 if (dump_file
4201 && !bitmap_bit_p (r_reachable, region->index))
4202 fprintf (dump_file,
4203 "Removing unreachable region %d\n",
4204 region->index);
4205 }
4206
4207 remove_unreachable_eh_regions (r_reachable);
4208
4209 sbitmap_free (r_reachable);
4210 }
4211
4212 /* Undo critical edge splitting on an EH landing pad. Earlier, we
4213 optimisticaly split all sorts of edges, including EH edges. The
4214 optimization passes in between may not have needed them; if not,
4215 we should undo the split.
4216
4217 Recognize this case by having one EH edge incoming to the BB and
4218 one normal edge outgoing; BB should be empty apart from the
4219 post_landing_pad label.
4220
4221 Note that this is slightly different from the empty handler case
4222 handled by cleanup_empty_eh, in that the actual handler may yet
4223 have actual code but the landing pad has been separated from the
4224 handler. As such, cleanup_empty_eh relies on this transformation
4225 having been done first. */
4226
4227 static bool
unsplit_eh(eh_landing_pad lp)4228 unsplit_eh (eh_landing_pad lp)
4229 {
4230 basic_block bb = label_to_block (cfun, lp->post_landing_pad);
4231 gimple_stmt_iterator gsi;
4232 edge e_in, e_out;
4233
4234 /* Quickly check the edge counts on BB for singularity. */
4235 if (!single_pred_p (bb) || !single_succ_p (bb))
4236 return false;
4237 e_in = single_pred_edge (bb);
4238 e_out = single_succ_edge (bb);
4239
4240 /* Input edge must be EH and output edge must be normal. */
4241 if ((e_in->flags & EDGE_EH) == 0 || (e_out->flags & EDGE_EH) != 0)
4242 return false;
4243
4244 /* The block must be empty except for the labels and debug insns. */
4245 gsi = gsi_after_labels (bb);
4246 if (!gsi_end_p (gsi) && is_gimple_debug (gsi_stmt (gsi)))
4247 gsi_next_nondebug (&gsi);
4248 if (!gsi_end_p (gsi))
4249 return false;
4250
4251 /* The destination block must not already have a landing pad
4252 for a different region. */
4253 for (gsi = gsi_start_bb (e_out->dest); !gsi_end_p (gsi); gsi_next (&gsi))
4254 {
4255 glabel *label_stmt = dyn_cast <glabel *> (gsi_stmt (gsi));
4256 tree lab;
4257 int lp_nr;
4258
4259 if (!label_stmt)
4260 break;
4261 lab = gimple_label_label (label_stmt);
4262 lp_nr = EH_LANDING_PAD_NR (lab);
4263 if (lp_nr && get_eh_region_from_lp_number (lp_nr) != lp->region)
4264 return false;
4265 }
4266
4267 /* The new destination block must not already be a destination of
4268 the source block, lest we merge fallthru and eh edges and get
4269 all sorts of confused. */
4270 if (find_edge (e_in->src, e_out->dest))
4271 return false;
4272
4273 /* ??? We can get degenerate phis due to cfg cleanups. I would have
4274 thought this should have been cleaned up by a phicprop pass, but
4275 that doesn't appear to handle virtuals. Propagate by hand. */
4276 if (!gimple_seq_empty_p (phi_nodes (bb)))
4277 {
4278 for (gphi_iterator gpi = gsi_start_phis (bb); !gsi_end_p (gpi); )
4279 {
4280 gimple *use_stmt;
4281 gphi *phi = gpi.phi ();
4282 tree lhs = gimple_phi_result (phi);
4283 tree rhs = gimple_phi_arg_def (phi, 0);
4284 use_operand_p use_p;
4285 imm_use_iterator iter;
4286
4287 FOR_EACH_IMM_USE_STMT (use_stmt, iter, lhs)
4288 {
4289 FOR_EACH_IMM_USE_ON_STMT (use_p, iter)
4290 SET_USE (use_p, rhs);
4291 }
4292
4293 if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (lhs))
4294 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (rhs) = 1;
4295
4296 remove_phi_node (&gpi, true);
4297 }
4298 }
4299
4300 if (dump_file && (dump_flags & TDF_DETAILS))
4301 fprintf (dump_file, "Unsplit EH landing pad %d to block %i.\n",
4302 lp->index, e_out->dest->index);
4303
4304 /* Redirect the edge. Since redirect_eh_edge_1 expects to be moving
4305 a successor edge, humor it. But do the real CFG change with the
4306 predecessor of E_OUT in order to preserve the ordering of arguments
4307 to the PHI nodes in E_OUT->DEST. */
4308 redirect_eh_edge_1 (e_in, e_out->dest, false);
4309 redirect_edge_pred (e_out, e_in->src);
4310 e_out->flags = e_in->flags;
4311 e_out->probability = e_in->probability;
4312 remove_edge (e_in);
4313
4314 return true;
4315 }
4316
4317 /* Examine each landing pad block and see if it matches unsplit_eh. */
4318
4319 static bool
unsplit_all_eh(void)4320 unsplit_all_eh (void)
4321 {
4322 bool changed = false;
4323 eh_landing_pad lp;
4324 int i;
4325
4326 for (i = 1; vec_safe_iterate (cfun->eh->lp_array, i, &lp); ++i)
4327 if (lp)
4328 changed |= unsplit_eh (lp);
4329
4330 return changed;
4331 }
4332
4333 /* Wrapper around unsplit_all_eh that makes it usable everywhere. */
4334
4335 void
unsplit_eh_edges(void)4336 unsplit_eh_edges (void)
4337 {
4338 bool changed;
4339
4340 /* unsplit_all_eh can die looking up unreachable landing pads. */
4341 maybe_remove_unreachable_handlers ();
4342
4343 changed = unsplit_all_eh ();
4344
4345 /* If EH edges have been unsplit, delete unreachable forwarder blocks. */
4346 if (changed)
4347 {
4348 free_dominance_info (CDI_DOMINATORS);
4349 free_dominance_info (CDI_POST_DOMINATORS);
4350 delete_unreachable_blocks ();
4351 }
4352 }
4353
4354 /* A subroutine of cleanup_empty_eh. Redirect all EH edges incoming
4355 to OLD_BB to NEW_BB; return true on success, false on failure.
4356
4357 OLD_BB_OUT is the edge into NEW_BB from OLD_BB, so if we miss any
4358 PHI variables from OLD_BB we can pick them up from OLD_BB_OUT.
4359 Virtual PHIs may be deleted and marked for renaming. */
4360
4361 static bool
cleanup_empty_eh_merge_phis(basic_block new_bb,basic_block old_bb,edge old_bb_out,bool change_region)4362 cleanup_empty_eh_merge_phis (basic_block new_bb, basic_block old_bb,
4363 edge old_bb_out, bool change_region)
4364 {
4365 gphi_iterator ngsi, ogsi;
4366 edge_iterator ei;
4367 edge e;
4368 bitmap ophi_handled;
4369
4370 /* The destination block must not be a regular successor for any
4371 of the preds of the landing pad. Thus, avoid turning
4372 <..>
4373 | \ EH
4374 | <..>
4375 | /
4376 <..>
4377 into
4378 <..>
4379 | | EH
4380 <..>
4381 which CFG verification would choke on. See PR45172 and PR51089. */
4382 if (!single_pred_p (new_bb))
4383 FOR_EACH_EDGE (e, ei, old_bb->preds)
4384 if (find_edge (e->src, new_bb))
4385 return false;
4386
4387 FOR_EACH_EDGE (e, ei, old_bb->preds)
4388 redirect_edge_var_map_clear (e);
4389
4390 ophi_handled = BITMAP_ALLOC (NULL);
4391
4392 /* First, iterate through the PHIs on NEW_BB and set up the edge_var_map
4393 for the edges we're going to move. */
4394 for (ngsi = gsi_start_phis (new_bb); !gsi_end_p (ngsi); gsi_next (&ngsi))
4395 {
4396 gphi *ophi, *nphi = ngsi.phi ();
4397 tree nresult, nop;
4398
4399 nresult = gimple_phi_result (nphi);
4400 nop = gimple_phi_arg_def (nphi, old_bb_out->dest_idx);
4401
4402 /* Find the corresponding PHI in OLD_BB so we can forward-propagate
4403 the source ssa_name. */
4404 ophi = NULL;
4405 for (ogsi = gsi_start_phis (old_bb); !gsi_end_p (ogsi); gsi_next (&ogsi))
4406 {
4407 ophi = ogsi.phi ();
4408 if (gimple_phi_result (ophi) == nop)
4409 break;
4410 ophi = NULL;
4411 }
4412
4413 /* If we did find the corresponding PHI, copy those inputs. */
4414 if (ophi)
4415 {
4416 /* If NOP is used somewhere else beyond phis in new_bb, give up. */
4417 if (!has_single_use (nop))
4418 {
4419 imm_use_iterator imm_iter;
4420 use_operand_p use_p;
4421
4422 FOR_EACH_IMM_USE_FAST (use_p, imm_iter, nop)
4423 {
4424 if (!gimple_debug_bind_p (USE_STMT (use_p))
4425 && (gimple_code (USE_STMT (use_p)) != GIMPLE_PHI
4426 || gimple_bb (USE_STMT (use_p)) != new_bb))
4427 goto fail;
4428 }
4429 }
4430 bitmap_set_bit (ophi_handled, SSA_NAME_VERSION (nop));
4431 FOR_EACH_EDGE (e, ei, old_bb->preds)
4432 {
4433 location_t oloc;
4434 tree oop;
4435
4436 if ((e->flags & EDGE_EH) == 0)
4437 continue;
4438 oop = gimple_phi_arg_def (ophi, e->dest_idx);
4439 oloc = gimple_phi_arg_location (ophi, e->dest_idx);
4440 redirect_edge_var_map_add (e, nresult, oop, oloc);
4441 }
4442 }
4443 /* If we didn't find the PHI, if it's a real variable or a VOP, we know
4444 from the fact that OLD_BB is tree_empty_eh_handler_p that the
4445 variable is unchanged from input to the block and we can simply
4446 re-use the input to NEW_BB from the OLD_BB_OUT edge. */
4447 else
4448 {
4449 location_t nloc
4450 = gimple_phi_arg_location (nphi, old_bb_out->dest_idx);
4451 FOR_EACH_EDGE (e, ei, old_bb->preds)
4452 redirect_edge_var_map_add (e, nresult, nop, nloc);
4453 }
4454 }
4455
4456 /* Second, verify that all PHIs from OLD_BB have been handled. If not,
4457 we don't know what values from the other edges into NEW_BB to use. */
4458 for (ogsi = gsi_start_phis (old_bb); !gsi_end_p (ogsi); gsi_next (&ogsi))
4459 {
4460 gphi *ophi = ogsi.phi ();
4461 tree oresult = gimple_phi_result (ophi);
4462 if (!bitmap_bit_p (ophi_handled, SSA_NAME_VERSION (oresult)))
4463 goto fail;
4464 }
4465
4466 /* Finally, move the edges and update the PHIs. */
4467 for (ei = ei_start (old_bb->preds); (e = ei_safe_edge (ei)); )
4468 if (e->flags & EDGE_EH)
4469 {
4470 /* ??? CFG manipluation routines do not try to update loop
4471 form on edge redirection. Do so manually here for now. */
4472 /* If we redirect a loop entry or latch edge that will either create
4473 a multiple entry loop or rotate the loop. If the loops merge
4474 we may have created a loop with multiple latches.
4475 All of this isn't easily fixed thus cancel the affected loop
4476 and mark the other loop as possibly having multiple latches. */
4477 if (e->dest == e->dest->loop_father->header)
4478 {
4479 mark_loop_for_removal (e->dest->loop_father);
4480 new_bb->loop_father->latch = NULL;
4481 loops_state_set (LOOPS_MAY_HAVE_MULTIPLE_LATCHES);
4482 }
4483 redirect_eh_edge_1 (e, new_bb, change_region);
4484 redirect_edge_succ (e, new_bb);
4485 flush_pending_stmts (e);
4486 }
4487 else
4488 ei_next (&ei);
4489
4490 BITMAP_FREE (ophi_handled);
4491 return true;
4492
4493 fail:
4494 FOR_EACH_EDGE (e, ei, old_bb->preds)
4495 redirect_edge_var_map_clear (e);
4496 BITMAP_FREE (ophi_handled);
4497 return false;
4498 }
4499
4500 /* A subroutine of cleanup_empty_eh. Move a landing pad LP from its
4501 old region to NEW_REGION at BB. */
4502
4503 static void
cleanup_empty_eh_move_lp(basic_block bb,edge e_out,eh_landing_pad lp,eh_region new_region)4504 cleanup_empty_eh_move_lp (basic_block bb, edge e_out,
4505 eh_landing_pad lp, eh_region new_region)
4506 {
4507 gimple_stmt_iterator gsi;
4508 eh_landing_pad *pp;
4509
4510 for (pp = &lp->region->landing_pads; *pp != lp; pp = &(*pp)->next_lp)
4511 continue;
4512 *pp = lp->next_lp;
4513
4514 lp->region = new_region;
4515 lp->next_lp = new_region->landing_pads;
4516 new_region->landing_pads = lp;
4517
4518 /* Delete the RESX that was matched within the empty handler block. */
4519 gsi = gsi_last_bb (bb);
4520 unlink_stmt_vdef (gsi_stmt (gsi));
4521 gsi_remove (&gsi, true);
4522
4523 /* Clean up E_OUT for the fallthru. */
4524 e_out->flags = (e_out->flags & ~EDGE_EH) | EDGE_FALLTHRU;
4525 e_out->probability = profile_probability::always ();
4526 }
4527
4528 /* A subroutine of cleanup_empty_eh. Handle more complex cases of
4529 unsplitting than unsplit_eh was prepared to handle, e.g. when
4530 multiple incoming edges and phis are involved. */
4531
4532 static bool
cleanup_empty_eh_unsplit(basic_block bb,edge e_out,eh_landing_pad lp)4533 cleanup_empty_eh_unsplit (basic_block bb, edge e_out, eh_landing_pad lp)
4534 {
4535 gimple_stmt_iterator gsi;
4536 tree lab;
4537
4538 /* We really ought not have totally lost everything following
4539 a landing pad label. Given that BB is empty, there had better
4540 be a successor. */
4541 gcc_assert (e_out != NULL);
4542
4543 /* The destination block must not already have a landing pad
4544 for a different region. */
4545 lab = NULL;
4546 for (gsi = gsi_start_bb (e_out->dest); !gsi_end_p (gsi); gsi_next (&gsi))
4547 {
4548 glabel *stmt = dyn_cast <glabel *> (gsi_stmt (gsi));
4549 int lp_nr;
4550
4551 if (!stmt)
4552 break;
4553 lab = gimple_label_label (stmt);
4554 lp_nr = EH_LANDING_PAD_NR (lab);
4555 if (lp_nr && get_eh_region_from_lp_number (lp_nr) != lp->region)
4556 return false;
4557 }
4558
4559 /* Attempt to move the PHIs into the successor block. */
4560 if (cleanup_empty_eh_merge_phis (e_out->dest, bb, e_out, false))
4561 {
4562 if (dump_file && (dump_flags & TDF_DETAILS))
4563 fprintf (dump_file,
4564 "Unsplit EH landing pad %d to block %i "
4565 "(via cleanup_empty_eh).\n",
4566 lp->index, e_out->dest->index);
4567 return true;
4568 }
4569
4570 return false;
4571 }
4572
4573 /* Return true if edge E_FIRST is part of an empty infinite loop
4574 or leads to such a loop through a series of single successor
4575 empty bbs. */
4576
4577 static bool
infinite_empty_loop_p(edge e_first)4578 infinite_empty_loop_p (edge e_first)
4579 {
4580 bool inf_loop = false;
4581 edge e;
4582
4583 if (e_first->dest == e_first->src)
4584 return true;
4585
4586 e_first->src->aux = (void *) 1;
4587 for (e = e_first; single_succ_p (e->dest); e = single_succ_edge (e->dest))
4588 {
4589 gimple_stmt_iterator gsi;
4590 if (e->dest->aux)
4591 {
4592 inf_loop = true;
4593 break;
4594 }
4595 e->dest->aux = (void *) 1;
4596 gsi = gsi_after_labels (e->dest);
4597 if (!gsi_end_p (gsi) && is_gimple_debug (gsi_stmt (gsi)))
4598 gsi_next_nondebug (&gsi);
4599 if (!gsi_end_p (gsi))
4600 break;
4601 }
4602 e_first->src->aux = NULL;
4603 for (e = e_first; e->dest->aux; e = single_succ_edge (e->dest))
4604 e->dest->aux = NULL;
4605
4606 return inf_loop;
4607 }
4608
4609 /* Examine the block associated with LP to determine if it's an empty
4610 handler for its EH region. If so, attempt to redirect EH edges to
4611 an outer region. Return true the CFG was updated in any way. This
4612 is similar to jump forwarding, just across EH edges. */
4613
4614 static bool
cleanup_empty_eh(eh_landing_pad lp)4615 cleanup_empty_eh (eh_landing_pad lp)
4616 {
4617 basic_block bb = label_to_block (cfun, lp->post_landing_pad);
4618 gimple_stmt_iterator gsi;
4619 gimple *resx;
4620 eh_region new_region;
4621 edge_iterator ei;
4622 edge e, e_out;
4623 bool has_non_eh_pred;
4624 bool ret = false;
4625 int new_lp_nr;
4626
4627 /* There can be zero or one edges out of BB. This is the quickest test. */
4628 switch (EDGE_COUNT (bb->succs))
4629 {
4630 case 0:
4631 e_out = NULL;
4632 break;
4633 case 1:
4634 e_out = single_succ_edge (bb);
4635 break;
4636 default:
4637 return false;
4638 }
4639
4640 gsi = gsi_last_nondebug_bb (bb);
4641 resx = gsi_stmt (gsi);
4642 if (resx && is_gimple_resx (resx))
4643 {
4644 if (stmt_can_throw_external (cfun, resx))
4645 optimize_clobbers (bb);
4646 else if (sink_clobbers (bb))
4647 ret = true;
4648 }
4649
4650 gsi = gsi_after_labels (bb);
4651
4652 /* Make sure to skip debug statements. */
4653 if (!gsi_end_p (gsi) && is_gimple_debug (gsi_stmt (gsi)))
4654 gsi_next_nondebug (&gsi);
4655
4656 /* If the block is totally empty, look for more unsplitting cases. */
4657 if (gsi_end_p (gsi))
4658 {
4659 /* For the degenerate case of an infinite loop bail out.
4660 If bb has no successors and is totally empty, which can happen e.g.
4661 because of incorrect noreturn attribute, bail out too. */
4662 if (e_out == NULL
4663 || infinite_empty_loop_p (e_out))
4664 return ret;
4665
4666 return ret | cleanup_empty_eh_unsplit (bb, e_out, lp);
4667 }
4668
4669 /* The block should consist only of a single RESX statement, modulo a
4670 preceding call to __builtin_stack_restore if there is no outgoing
4671 edge, since the call can be eliminated in this case. */
4672 resx = gsi_stmt (gsi);
4673 if (!e_out && gimple_call_builtin_p (resx, BUILT_IN_STACK_RESTORE))
4674 {
4675 gsi_next_nondebug (&gsi);
4676 resx = gsi_stmt (gsi);
4677 }
4678 if (!is_gimple_resx (resx))
4679 return ret;
4680 gcc_assert (gsi_one_nondebug_before_end_p (gsi));
4681
4682 /* Determine if there are non-EH edges, or resx edges into the handler. */
4683 has_non_eh_pred = false;
4684 FOR_EACH_EDGE (e, ei, bb->preds)
4685 if (!(e->flags & EDGE_EH))
4686 has_non_eh_pred = true;
4687
4688 /* Find the handler that's outer of the empty handler by looking at
4689 where the RESX instruction was vectored. */
4690 new_lp_nr = lookup_stmt_eh_lp (resx);
4691 new_region = get_eh_region_from_lp_number (new_lp_nr);
4692
4693 /* If there's no destination region within the current function,
4694 redirection is trivial via removing the throwing statements from
4695 the EH region, removing the EH edges, and allowing the block
4696 to go unreachable. */
4697 if (new_region == NULL)
4698 {
4699 gcc_assert (e_out == NULL);
4700 for (ei = ei_start (bb->preds); (e = ei_safe_edge (ei)); )
4701 if (e->flags & EDGE_EH)
4702 {
4703 gimple *stmt = last_stmt (e->src);
4704 remove_stmt_from_eh_lp (stmt);
4705 remove_edge (e);
4706 }
4707 else
4708 ei_next (&ei);
4709 goto succeed;
4710 }
4711
4712 /* If the destination region is a MUST_NOT_THROW, allow the runtime
4713 to handle the abort and allow the blocks to go unreachable. */
4714 if (new_region->type == ERT_MUST_NOT_THROW)
4715 {
4716 for (ei = ei_start (bb->preds); (e = ei_safe_edge (ei)); )
4717 if (e->flags & EDGE_EH)
4718 {
4719 gimple *stmt = last_stmt (e->src);
4720 remove_stmt_from_eh_lp (stmt);
4721 add_stmt_to_eh_lp (stmt, new_lp_nr);
4722 remove_edge (e);
4723 }
4724 else
4725 ei_next (&ei);
4726 goto succeed;
4727 }
4728
4729 /* Try to redirect the EH edges and merge the PHIs into the destination
4730 landing pad block. If the merge succeeds, we'll already have redirected
4731 all the EH edges. The handler itself will go unreachable if there were
4732 no normal edges. */
4733 if (cleanup_empty_eh_merge_phis (e_out->dest, bb, e_out, true))
4734 goto succeed;
4735
4736 /* Finally, if all input edges are EH edges, then we can (potentially)
4737 reduce the number of transfers from the runtime by moving the landing
4738 pad from the original region to the new region. This is a win when
4739 we remove the last CLEANUP region along a particular exception
4740 propagation path. Since nothing changes except for the region with
4741 which the landing pad is associated, the PHI nodes do not need to be
4742 adjusted at all. */
4743 if (!has_non_eh_pred)
4744 {
4745 cleanup_empty_eh_move_lp (bb, e_out, lp, new_region);
4746 if (dump_file && (dump_flags & TDF_DETAILS))
4747 fprintf (dump_file, "Empty EH handler %i moved to EH region %i.\n",
4748 lp->index, new_region->index);
4749
4750 /* ??? The CFG didn't change, but we may have rendered the
4751 old EH region unreachable. Trigger a cleanup there. */
4752 return true;
4753 }
4754
4755 return ret;
4756
4757 succeed:
4758 if (dump_file && (dump_flags & TDF_DETAILS))
4759 fprintf (dump_file, "Empty EH handler %i removed.\n", lp->index);
4760 remove_eh_landing_pad (lp);
4761 return true;
4762 }
4763
4764 /* Do a post-order traversal of the EH region tree. Examine each
4765 post_landing_pad block and see if we can eliminate it as empty. */
4766
4767 static bool
cleanup_all_empty_eh(void)4768 cleanup_all_empty_eh (void)
4769 {
4770 bool changed = false;
4771 eh_landing_pad lp;
4772 int i;
4773
4774 /* The post-order traversal may lead to quadraticness in the redirection
4775 of incoming EH edges from inner LPs, so first try to walk the region
4776 tree from inner to outer LPs in order to eliminate these edges. */
4777 for (i = vec_safe_length (cfun->eh->lp_array) - 1; i >= 1; --i)
4778 {
4779 lp = (*cfun->eh->lp_array)[i];
4780 if (lp)
4781 changed |= cleanup_empty_eh (lp);
4782 }
4783
4784 /* Now do the post-order traversal to eliminate outer empty LPs. */
4785 for (i = 1; vec_safe_iterate (cfun->eh->lp_array, i, &lp); ++i)
4786 if (lp)
4787 changed |= cleanup_empty_eh (lp);
4788
4789 return changed;
4790 }
4791
4792 /* Perform cleanups and lowering of exception handling
4793 1) cleanups regions with handlers doing nothing are optimized out
4794 2) MUST_NOT_THROW regions that became dead because of 1) are optimized out
4795 3) Info about regions that are containing instructions, and regions
4796 reachable via local EH edges is collected
4797 4) Eh tree is pruned for regions no longer necessary.
4798
4799 TODO: Push MUST_NOT_THROW regions to the root of the EH tree.
4800 Unify those that have the same failure decl and locus.
4801 */
4802
4803 static unsigned int
execute_cleanup_eh_1(void)4804 execute_cleanup_eh_1 (void)
4805 {
4806 /* Do this first: unsplit_all_eh and cleanup_all_empty_eh can die
4807 looking up unreachable landing pads. */
4808 remove_unreachable_handlers ();
4809
4810 /* Watch out for the region tree vanishing due to all unreachable. */
4811 if (cfun->eh->region_tree)
4812 {
4813 bool changed = false;
4814
4815 if (optimize)
4816 changed |= unsplit_all_eh ();
4817 changed |= cleanup_all_empty_eh ();
4818
4819 if (changed)
4820 {
4821 free_dominance_info (CDI_DOMINATORS);
4822 free_dominance_info (CDI_POST_DOMINATORS);
4823
4824 /* We delayed all basic block deletion, as we may have performed
4825 cleanups on EH edges while non-EH edges were still present. */
4826 delete_unreachable_blocks ();
4827
4828 /* We manipulated the landing pads. Remove any region that no
4829 longer has a landing pad. */
4830 remove_unreachable_handlers_no_lp ();
4831
4832 return TODO_cleanup_cfg | TODO_update_ssa_only_virtuals;
4833 }
4834 }
4835
4836 return 0;
4837 }
4838
4839 namespace {
4840
4841 const pass_data pass_data_cleanup_eh =
4842 {
4843 GIMPLE_PASS, /* type */
4844 "ehcleanup", /* name */
4845 OPTGROUP_NONE, /* optinfo_flags */
4846 TV_TREE_EH, /* tv_id */
4847 PROP_gimple_lcf, /* properties_required */
4848 0, /* properties_provided */
4849 0, /* properties_destroyed */
4850 0, /* todo_flags_start */
4851 0, /* todo_flags_finish */
4852 };
4853
4854 class pass_cleanup_eh : public gimple_opt_pass
4855 {
4856 public:
pass_cleanup_eh(gcc::context * ctxt)4857 pass_cleanup_eh (gcc::context *ctxt)
4858 : gimple_opt_pass (pass_data_cleanup_eh, ctxt)
4859 {}
4860
4861 /* opt_pass methods: */
clone()4862 opt_pass * clone () { return new pass_cleanup_eh (m_ctxt); }
gate(function * fun)4863 virtual bool gate (function *fun)
4864 {
4865 return fun->eh != NULL && fun->eh->region_tree != NULL;
4866 }
4867
4868 virtual unsigned int execute (function *);
4869
4870 }; // class pass_cleanup_eh
4871
4872 unsigned int
execute(function * fun)4873 pass_cleanup_eh::execute (function *fun)
4874 {
4875 int ret = execute_cleanup_eh_1 ();
4876
4877 /* If the function no longer needs an EH personality routine
4878 clear it. This exposes cross-language inlining opportunities
4879 and avoids references to a never defined personality routine. */
4880 if (DECL_FUNCTION_PERSONALITY (current_function_decl)
4881 && function_needs_eh_personality (fun) != eh_personality_lang)
4882 DECL_FUNCTION_PERSONALITY (current_function_decl) = NULL_TREE;
4883
4884 return ret;
4885 }
4886
4887 } // anon namespace
4888
4889 gimple_opt_pass *
make_pass_cleanup_eh(gcc::context * ctxt)4890 make_pass_cleanup_eh (gcc::context *ctxt)
4891 {
4892 return new pass_cleanup_eh (ctxt);
4893 }
4894
4895 /* Disable warnings about missing quoting in GCC diagnostics for
4896 the verification errors. Their format strings don't follow GCC
4897 diagnostic conventions but are only used for debugging. */
4898 #if __GNUC__ >= 10
4899 # pragma GCC diagnostic push
4900 # pragma GCC diagnostic ignored "-Wformat-diag"
4901 #endif
4902
4903 /* Verify that BB containing STMT as the last statement, has precisely the
4904 edge that make_eh_edges would create. */
4905
4906 DEBUG_FUNCTION bool
verify_eh_edges(gimple * stmt)4907 verify_eh_edges (gimple *stmt)
4908 {
4909 basic_block bb = gimple_bb (stmt);
4910 eh_landing_pad lp = NULL;
4911 int lp_nr;
4912 edge_iterator ei;
4913 edge e, eh_edge;
4914
4915 lp_nr = lookup_stmt_eh_lp (stmt);
4916 if (lp_nr > 0)
4917 lp = get_eh_landing_pad_from_number (lp_nr);
4918
4919 eh_edge = NULL;
4920 FOR_EACH_EDGE (e, ei, bb->succs)
4921 {
4922 if (e->flags & EDGE_EH)
4923 {
4924 if (eh_edge)
4925 {
4926 error ("BB %i has multiple EH edges", bb->index);
4927 return true;
4928 }
4929 else
4930 eh_edge = e;
4931 }
4932 }
4933
4934 if (lp == NULL)
4935 {
4936 if (eh_edge)
4937 {
4938 error ("BB %i cannot throw but has an EH edge", bb->index);
4939 return true;
4940 }
4941 return false;
4942 }
4943
4944 if (!stmt_could_throw_p (cfun, stmt))
4945 {
4946 error ("BB %i last statement has incorrectly set lp", bb->index);
4947 return true;
4948 }
4949
4950 if (eh_edge == NULL)
4951 {
4952 error ("BB %i is missing an EH edge", bb->index);
4953 return true;
4954 }
4955
4956 if (eh_edge->dest != label_to_block (cfun, lp->post_landing_pad))
4957 {
4958 error ("Incorrect EH edge %i->%i", bb->index, eh_edge->dest->index);
4959 return true;
4960 }
4961
4962 return false;
4963 }
4964
4965 /* Similarly, but handle GIMPLE_EH_DISPATCH specifically. */
4966
4967 DEBUG_FUNCTION bool
verify_eh_dispatch_edge(geh_dispatch * stmt)4968 verify_eh_dispatch_edge (geh_dispatch *stmt)
4969 {
4970 eh_region r;
4971 eh_catch c;
4972 basic_block src, dst;
4973 bool want_fallthru = true;
4974 edge_iterator ei;
4975 edge e, fall_edge;
4976
4977 r = get_eh_region_from_number (gimple_eh_dispatch_region (stmt));
4978 src = gimple_bb (stmt);
4979
4980 FOR_EACH_EDGE (e, ei, src->succs)
4981 gcc_assert (e->aux == NULL);
4982
4983 switch (r->type)
4984 {
4985 case ERT_TRY:
4986 for (c = r->u.eh_try.first_catch; c ; c = c->next_catch)
4987 {
4988 dst = label_to_block (cfun, c->label);
4989 e = find_edge (src, dst);
4990 if (e == NULL)
4991 {
4992 error ("BB %i is missing an edge", src->index);
4993 return true;
4994 }
4995 e->aux = (void *)e;
4996
4997 /* A catch-all handler doesn't have a fallthru. */
4998 if (c->type_list == NULL)
4999 {
5000 want_fallthru = false;
5001 break;
5002 }
5003 }
5004 break;
5005
5006 case ERT_ALLOWED_EXCEPTIONS:
5007 dst = label_to_block (cfun, r->u.allowed.label);
5008 e = find_edge (src, dst);
5009 if (e == NULL)
5010 {
5011 error ("BB %i is missing an edge", src->index);
5012 return true;
5013 }
5014 e->aux = (void *)e;
5015 break;
5016
5017 default:
5018 gcc_unreachable ();
5019 }
5020
5021 fall_edge = NULL;
5022 FOR_EACH_EDGE (e, ei, src->succs)
5023 {
5024 if (e->flags & EDGE_FALLTHRU)
5025 {
5026 if (fall_edge != NULL)
5027 {
5028 error ("BB %i too many fallthru edges", src->index);
5029 return true;
5030 }
5031 fall_edge = e;
5032 }
5033 else if (e->aux)
5034 e->aux = NULL;
5035 else
5036 {
5037 error ("BB %i has incorrect edge", src->index);
5038 return true;
5039 }
5040 }
5041 if ((fall_edge != NULL) ^ want_fallthru)
5042 {
5043 error ("BB %i has incorrect fallthru edge", src->index);
5044 return true;
5045 }
5046
5047 return false;
5048 }
5049
5050 #if __GNUC__ >= 10
5051 # pragma GCC diagnostic pop
5052 #endif
5053