1 /* Control flow functions for trees.
2 Copyright (C) 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
3 Contributed by Diego Novillo <dnovillo@redhat.com>
4
5 This file is part of GCC.
6
7 GCC is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
10 any later version.
11
12 GCC is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
16
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to
19 the Free Software Foundation, 51 Franklin Street, Fifth Floor,
20 Boston, MA 02110-1301, USA. */
21
22 #include "config.h"
23 #include "system.h"
24 #include "coretypes.h"
25 #include "tm.h"
26 #include "tree.h"
27 #include "rtl.h"
28 #include "tm_p.h"
29 #include "hard-reg-set.h"
30 #include "basic-block.h"
31 #include "output.h"
32 #include "flags.h"
33 #include "function.h"
34 #include "expr.h"
35 #include "ggc.h"
36 #include "langhooks.h"
37 #include "diagnostic.h"
38 #include "tree-flow.h"
39 #include "timevar.h"
40 #include "tree-dump.h"
41 #include "tree-pass.h"
42 #include "toplev.h"
43 #include "except.h"
44 #include "cfgloop.h"
45 #include "cfglayout.h"
46 #include "hashtab.h"
47 #include "tree-ssa-propagate.h"
48
49 /* This file contains functions for building the Control Flow Graph (CFG)
50 for a function tree. */
51
52 /* Local declarations. */
53
54 /* Initial capacity for the basic block array. */
55 static const int initial_cfg_capacity = 20;
56
57 /* This hash table allows us to efficiently lookup all CASE_LABEL_EXPRs
58 which use a particular edge. The CASE_LABEL_EXPRs are chained together
59 via their TREE_CHAIN field, which we clear after we're done with the
60 hash table to prevent problems with duplication of SWITCH_EXPRs.
61
62 Access to this list of CASE_LABEL_EXPRs allows us to efficiently
63 update the case vector in response to edge redirections.
64
65 Right now this table is set up and torn down at key points in the
66 compilation process. It would be nice if we could make the table
67 more persistent. The key is getting notification of changes to
68 the CFG (particularly edge removal, creation and redirection). */
69
70 struct edge_to_cases_elt
71 {
72 /* The edge itself. Necessary for hashing and equality tests. */
73 edge e;
74
75 /* The case labels associated with this edge. We link these up via
76 their TREE_CHAIN field, then we wipe out the TREE_CHAIN fields
77 when we destroy the hash table. This prevents problems when copying
78 SWITCH_EXPRs. */
79 tree case_labels;
80 };
81
82 static htab_t edge_to_cases;
83
84 /* CFG statistics. */
85 struct cfg_stats_d
86 {
87 long num_merged_labels;
88 };
89
90 static struct cfg_stats_d cfg_stats;
91
92 /* Nonzero if we found a computed goto while building basic blocks. */
93 static bool found_computed_goto;
94
95 /* Basic blocks and flowgraphs. */
96 static basic_block create_bb (void *, void *, basic_block);
97 static void make_blocks (tree);
98 static void factor_computed_gotos (void);
99
100 /* Edges. */
101 static void make_edges (void);
102 static void make_ctrl_stmt_edges (basic_block);
103 static void make_exit_edges (basic_block);
104 static void make_cond_expr_edges (basic_block);
105 static void make_switch_expr_edges (basic_block);
106 static void make_goto_expr_edges (basic_block);
107 static edge tree_redirect_edge_and_branch (edge, basic_block);
108 static edge tree_try_redirect_by_replacing_jump (edge, basic_block);
109 static void split_critical_edges (void);
110
111 /* Various helpers. */
112 static inline bool stmt_starts_bb_p (tree, tree);
113 static int tree_verify_flow_info (void);
114 static void tree_make_forwarder_block (edge);
115 static void tree_cfg2vcg (FILE *);
116
117 /* Flowgraph optimization and cleanup. */
118 static void tree_merge_blocks (basic_block, basic_block);
119 static bool tree_can_merge_blocks_p (basic_block, basic_block);
120 static void remove_bb (basic_block);
121 static edge find_taken_edge_computed_goto (basic_block, tree);
122 static edge find_taken_edge_cond_expr (basic_block, tree);
123 static edge find_taken_edge_switch_expr (basic_block, tree);
124 static tree find_case_label_for_value (tree, tree);
125
126 void
init_empty_tree_cfg(void)127 init_empty_tree_cfg (void)
128 {
129 /* Initialize the basic block array. */
130 init_flow ();
131 profile_status = PROFILE_ABSENT;
132 n_basic_blocks = 0;
133 last_basic_block = 0;
134 VARRAY_BB_INIT (basic_block_info, initial_cfg_capacity, "basic_block_info");
135
136 /* Build a mapping of labels to their associated blocks. */
137 VARRAY_BB_INIT (label_to_block_map, initial_cfg_capacity,
138 "label to block map");
139
140 ENTRY_BLOCK_PTR->next_bb = EXIT_BLOCK_PTR;
141 EXIT_BLOCK_PTR->prev_bb = ENTRY_BLOCK_PTR;
142 }
143
144 /*---------------------------------------------------------------------------
145 Create basic blocks
146 ---------------------------------------------------------------------------*/
147
148 /* Entry point to the CFG builder for trees. TP points to the list of
149 statements to be added to the flowgraph. */
150
151 static void
build_tree_cfg(tree * tp)152 build_tree_cfg (tree *tp)
153 {
154 /* Register specific tree functions. */
155 tree_register_cfg_hooks ();
156
157 memset ((void *) &cfg_stats, 0, sizeof (cfg_stats));
158
159 init_empty_tree_cfg ();
160
161 found_computed_goto = 0;
162 make_blocks (*tp);
163
164 /* Computed gotos are hell to deal with, especially if there are
165 lots of them with a large number of destinations. So we factor
166 them to a common computed goto location before we build the
167 edge list. After we convert back to normal form, we will un-factor
168 the computed gotos since factoring introduces an unwanted jump. */
169 if (found_computed_goto)
170 factor_computed_gotos ();
171
172 /* Make sure there is always at least one block, even if it's empty. */
173 if (n_basic_blocks == 0)
174 create_empty_bb (ENTRY_BLOCK_PTR);
175
176 /* Adjust the size of the array. */
177 VARRAY_GROW (basic_block_info, n_basic_blocks);
178
179 /* To speed up statement iterator walks, we first purge dead labels. */
180 cleanup_dead_labels ();
181
182 /* Group case nodes to reduce the number of edges.
183 We do this after cleaning up dead labels because otherwise we miss
184 a lot of obvious case merging opportunities. */
185 group_case_labels ();
186
187 /* Create the edges of the flowgraph. */
188 make_edges ();
189
190 /* Debugging dumps. */
191
192 /* Write the flowgraph to a VCG file. */
193 {
194 int local_dump_flags;
195 FILE *dump_file = dump_begin (TDI_vcg, &local_dump_flags);
196 if (dump_file)
197 {
198 tree_cfg2vcg (dump_file);
199 dump_end (TDI_vcg, dump_file);
200 }
201 }
202
203 #ifdef ENABLE_CHECKING
204 verify_stmts ();
205 #endif
206
207 /* Dump a textual representation of the flowgraph. */
208 if (dump_file)
209 dump_tree_cfg (dump_file, dump_flags);
210 }
211
212 static void
execute_build_cfg(void)213 execute_build_cfg (void)
214 {
215 build_tree_cfg (&DECL_SAVED_TREE (current_function_decl));
216 }
217
218 struct tree_opt_pass pass_build_cfg =
219 {
220 "cfg", /* name */
221 NULL, /* gate */
222 execute_build_cfg, /* execute */
223 NULL, /* sub */
224 NULL, /* next */
225 0, /* static_pass_number */
226 TV_TREE_CFG, /* tv_id */
227 PROP_gimple_leh, /* properties_required */
228 PROP_cfg, /* properties_provided */
229 0, /* properties_destroyed */
230 0, /* todo_flags_start */
231 TODO_verify_stmts, /* todo_flags_finish */
232 0 /* letter */
233 };
234
235 /* Search the CFG for any computed gotos. If found, factor them to a
236 common computed goto site. Also record the location of that site so
237 that we can un-factor the gotos after we have converted back to
238 normal form. */
239
240 static void
factor_computed_gotos(void)241 factor_computed_gotos (void)
242 {
243 basic_block bb;
244 tree factored_label_decl = NULL;
245 tree var = NULL;
246 tree factored_computed_goto_label = NULL;
247 tree factored_computed_goto = NULL;
248
249 /* We know there are one or more computed gotos in this function.
250 Examine the last statement in each basic block to see if the block
251 ends with a computed goto. */
252
253 FOR_EACH_BB (bb)
254 {
255 block_stmt_iterator bsi = bsi_last (bb);
256 tree last;
257
258 if (bsi_end_p (bsi))
259 continue;
260 last = bsi_stmt (bsi);
261
262 /* Ignore the computed goto we create when we factor the original
263 computed gotos. */
264 if (last == factored_computed_goto)
265 continue;
266
267 /* If the last statement is a computed goto, factor it. */
268 if (computed_goto_p (last))
269 {
270 tree assignment;
271
272 /* The first time we find a computed goto we need to create
273 the factored goto block and the variable each original
274 computed goto will use for their goto destination. */
275 if (! factored_computed_goto)
276 {
277 basic_block new_bb = create_empty_bb (bb);
278 block_stmt_iterator new_bsi = bsi_start (new_bb);
279
280 /* Create the destination of the factored goto. Each original
281 computed goto will put its desired destination into this
282 variable and jump to the label we create immediately
283 below. */
284 var = create_tmp_var (ptr_type_node, "gotovar");
285
286 /* Build a label for the new block which will contain the
287 factored computed goto. */
288 factored_label_decl = create_artificial_label ();
289 factored_computed_goto_label
290 = build1 (LABEL_EXPR, void_type_node, factored_label_decl);
291 bsi_insert_after (&new_bsi, factored_computed_goto_label,
292 BSI_NEW_STMT);
293
294 /* Build our new computed goto. */
295 factored_computed_goto = build1 (GOTO_EXPR, void_type_node, var);
296 bsi_insert_after (&new_bsi, factored_computed_goto,
297 BSI_NEW_STMT);
298 }
299
300 /* Copy the original computed goto's destination into VAR. */
301 assignment = build (MODIFY_EXPR, ptr_type_node,
302 var, GOTO_DESTINATION (last));
303 bsi_insert_before (&bsi, assignment, BSI_SAME_STMT);
304
305 /* And re-vector the computed goto to the new destination. */
306 GOTO_DESTINATION (last) = factored_label_decl;
307 }
308 }
309 }
310
311
312 /* Build a flowgraph for the statement_list STMT_LIST. */
313
314 static void
make_blocks(tree stmt_list)315 make_blocks (tree stmt_list)
316 {
317 tree_stmt_iterator i = tsi_start (stmt_list);
318 tree stmt = NULL;
319 bool start_new_block = true;
320 bool first_stmt_of_list = true;
321 basic_block bb = ENTRY_BLOCK_PTR;
322
323 while (!tsi_end_p (i))
324 {
325 tree prev_stmt;
326
327 prev_stmt = stmt;
328 stmt = tsi_stmt (i);
329
330 /* If the statement starts a new basic block or if we have determined
331 in a previous pass that we need to create a new block for STMT, do
332 so now. */
333 if (start_new_block || stmt_starts_bb_p (stmt, prev_stmt))
334 {
335 if (!first_stmt_of_list)
336 stmt_list = tsi_split_statement_list_before (&i);
337 bb = create_basic_block (stmt_list, NULL, bb);
338 start_new_block = false;
339 }
340
341 /* Now add STMT to BB and create the subgraphs for special statement
342 codes. */
343 set_bb_for_stmt (stmt, bb);
344
345 if (computed_goto_p (stmt))
346 found_computed_goto = true;
347
348 /* If STMT is a basic block terminator, set START_NEW_BLOCK for the
349 next iteration. */
350 if (stmt_ends_bb_p (stmt))
351 start_new_block = true;
352
353 tsi_next (&i);
354 first_stmt_of_list = false;
355 }
356 }
357
358
359 /* Create and return a new empty basic block after bb AFTER. */
360
361 static basic_block
create_bb(void * h,void * e,basic_block after)362 create_bb (void *h, void *e, basic_block after)
363 {
364 basic_block bb;
365
366 gcc_assert (!e);
367
368 /* Create and initialize a new basic block. Since alloc_block uses
369 ggc_alloc_cleared to allocate a basic block, we do not have to
370 clear the newly allocated basic block here. */
371 bb = alloc_block ();
372
373 bb->index = last_basic_block;
374 bb->flags = BB_NEW;
375 bb->stmt_list = h ? h : alloc_stmt_list ();
376
377 /* Add the new block to the linked list of blocks. */
378 link_block (bb, after);
379
380 /* Grow the basic block array if needed. */
381 if ((size_t) last_basic_block == VARRAY_SIZE (basic_block_info))
382 {
383 size_t new_size = last_basic_block + (last_basic_block + 3) / 4;
384 VARRAY_GROW (basic_block_info, new_size);
385 }
386
387 /* Add the newly created block to the array. */
388 BASIC_BLOCK (last_basic_block) = bb;
389
390 n_basic_blocks++;
391 last_basic_block++;
392
393 return bb;
394 }
395
396
397 /*---------------------------------------------------------------------------
398 Edge creation
399 ---------------------------------------------------------------------------*/
400
401 /* Fold COND_EXPR_COND of each COND_EXPR. */
402
403 void
fold_cond_expr_cond(void)404 fold_cond_expr_cond (void)
405 {
406 basic_block bb;
407
408 FOR_EACH_BB (bb)
409 {
410 tree stmt = last_stmt (bb);
411
412 if (stmt
413 && TREE_CODE (stmt) == COND_EXPR)
414 {
415 tree cond = fold (COND_EXPR_COND (stmt));
416 if (integer_zerop (cond))
417 COND_EXPR_COND (stmt) = boolean_false_node;
418 else if (integer_onep (cond))
419 COND_EXPR_COND (stmt) = boolean_true_node;
420 }
421 }
422 }
423
424 /* Join all the blocks in the flowgraph. */
425
426 static void
make_edges(void)427 make_edges (void)
428 {
429 basic_block bb;
430
431 /* Create an edge from entry to the first block with executable
432 statements in it. */
433 make_edge (ENTRY_BLOCK_PTR, BASIC_BLOCK (0), EDGE_FALLTHRU);
434
435 /* Traverse the basic block array placing edges. */
436 FOR_EACH_BB (bb)
437 {
438 tree first = first_stmt (bb);
439 tree last = last_stmt (bb);
440
441 if (first)
442 {
443 /* Edges for statements that always alter flow control. */
444 if (is_ctrl_stmt (last))
445 make_ctrl_stmt_edges (bb);
446
447 /* Edges for statements that sometimes alter flow control. */
448 if (is_ctrl_altering_stmt (last))
449 make_exit_edges (bb);
450 }
451
452 /* Finally, if no edges were created above, this is a regular
453 basic block that only needs a fallthru edge. */
454 if (EDGE_COUNT (bb->succs) == 0)
455 make_edge (bb, bb->next_bb, EDGE_FALLTHRU);
456 }
457
458 /* We do not care about fake edges, so remove any that the CFG
459 builder inserted for completeness. */
460 remove_fake_exit_edges ();
461
462 /* Fold COND_EXPR_COND of each COND_EXPR. */
463 fold_cond_expr_cond ();
464
465 /* Clean up the graph and warn for unreachable code. */
466 cleanup_tree_cfg ();
467 }
468
469
470 /* Create edges for control statement at basic block BB. */
471
472 static void
make_ctrl_stmt_edges(basic_block bb)473 make_ctrl_stmt_edges (basic_block bb)
474 {
475 tree last = last_stmt (bb);
476
477 gcc_assert (last);
478 switch (TREE_CODE (last))
479 {
480 case GOTO_EXPR:
481 make_goto_expr_edges (bb);
482 break;
483
484 case RETURN_EXPR:
485 make_edge (bb, EXIT_BLOCK_PTR, 0);
486 break;
487
488 case COND_EXPR:
489 make_cond_expr_edges (bb);
490 break;
491
492 case SWITCH_EXPR:
493 make_switch_expr_edges (bb);
494 break;
495
496 case RESX_EXPR:
497 make_eh_edges (last);
498 /* Yet another NORETURN hack. */
499 if (EDGE_COUNT (bb->succs) == 0)
500 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
501 break;
502
503 default:
504 gcc_unreachable ();
505 }
506 }
507
508
509 /* Create exit edges for statements in block BB that alter the flow of
510 control. Statements that alter the control flow are 'goto', 'return'
511 and calls to non-returning functions. */
512
513 static void
make_exit_edges(basic_block bb)514 make_exit_edges (basic_block bb)
515 {
516 tree last = last_stmt (bb), op;
517
518 gcc_assert (last);
519 switch (TREE_CODE (last))
520 {
521 case RESX_EXPR:
522 break;
523 case CALL_EXPR:
524 /* If this function receives a nonlocal goto, then we need to
525 make edges from this call site to all the nonlocal goto
526 handlers. */
527 if (TREE_SIDE_EFFECTS (last)
528 && current_function_has_nonlocal_label)
529 make_goto_expr_edges (bb);
530
531 /* If this statement has reachable exception handlers, then
532 create abnormal edges to them. */
533 make_eh_edges (last);
534
535 /* Some calls are known not to return. For such calls we create
536 a fake edge.
537
538 We really need to revamp how we build edges so that it's not
539 such a bloody pain to avoid creating edges for this case since
540 all we do is remove these edges when we're done building the
541 CFG. */
542 if (call_expr_flags (last) & ECF_NORETURN)
543 {
544 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
545 return;
546 }
547
548 /* Don't forget the fall-thru edge. */
549 make_edge (bb, bb->next_bb, EDGE_FALLTHRU);
550 break;
551
552 case MODIFY_EXPR:
553 /* A MODIFY_EXPR may have a CALL_EXPR on its RHS and the CALL_EXPR
554 may have an abnormal edge. Search the RHS for this case and
555 create any required edges. */
556 op = get_call_expr_in (last);
557 if (op && TREE_SIDE_EFFECTS (op)
558 && current_function_has_nonlocal_label)
559 make_goto_expr_edges (bb);
560
561 make_eh_edges (last);
562 make_edge (bb, bb->next_bb, EDGE_FALLTHRU);
563 break;
564
565 default:
566 gcc_unreachable ();
567 }
568 }
569
570
571 /* Create the edges for a COND_EXPR starting at block BB.
572 At this point, both clauses must contain only simple gotos. */
573
574 static void
make_cond_expr_edges(basic_block bb)575 make_cond_expr_edges (basic_block bb)
576 {
577 tree entry = last_stmt (bb);
578 basic_block then_bb, else_bb;
579 tree then_label, else_label;
580 edge e;
581
582 gcc_assert (entry);
583 gcc_assert (TREE_CODE (entry) == COND_EXPR);
584
585 /* Entry basic blocks for each component. */
586 then_label = GOTO_DESTINATION (COND_EXPR_THEN (entry));
587 else_label = GOTO_DESTINATION (COND_EXPR_ELSE (entry));
588 then_bb = label_to_block (then_label);
589 else_bb = label_to_block (else_label);
590
591 e = make_edge (bb, then_bb, EDGE_TRUE_VALUE);
592 #ifdef USE_MAPPED_LOCATION
593 e->goto_locus = EXPR_LOCATION (COND_EXPR_THEN (entry));
594 #else
595 e->goto_locus = EXPR_LOCUS (COND_EXPR_THEN (entry));
596 #endif
597 e = make_edge (bb, else_bb, EDGE_FALSE_VALUE);
598 if (e)
599 {
600 #ifdef USE_MAPPED_LOCATION
601 e->goto_locus = EXPR_LOCATION (COND_EXPR_ELSE (entry));
602 #else
603 e->goto_locus = EXPR_LOCUS (COND_EXPR_ELSE (entry));
604 #endif
605 }
606 }
607
608 /* Hashing routine for EDGE_TO_CASES. */
609
610 static hashval_t
edge_to_cases_hash(const void * p)611 edge_to_cases_hash (const void *p)
612 {
613 edge e = ((struct edge_to_cases_elt *)p)->e;
614
615 /* Hash on the edge itself (which is a pointer). */
616 return htab_hash_pointer (e);
617 }
618
619 /* Equality routine for EDGE_TO_CASES, edges are unique, so testing
620 for equality is just a pointer comparison. */
621
622 static int
edge_to_cases_eq(const void * p1,const void * p2)623 edge_to_cases_eq (const void *p1, const void *p2)
624 {
625 edge e1 = ((struct edge_to_cases_elt *)p1)->e;
626 edge e2 = ((struct edge_to_cases_elt *)p2)->e;
627
628 return e1 == e2;
629 }
630
631 /* Called for each element in the hash table (P) as we delete the
632 edge to cases hash table.
633
634 Clear all the TREE_CHAINs to prevent problems with copying of
635 SWITCH_EXPRs and structure sharing rules, then free the hash table
636 element. */
637
638 static void
edge_to_cases_cleanup(void * p)639 edge_to_cases_cleanup (void *p)
640 {
641 struct edge_to_cases_elt *elt = p;
642 tree t, next;
643
644 for (t = elt->case_labels; t; t = next)
645 {
646 next = TREE_CHAIN (t);
647 TREE_CHAIN (t) = NULL;
648 }
649 free (p);
650 }
651
652 /* Start recording information mapping edges to case labels. */
653
654 void
start_recording_case_labels(void)655 start_recording_case_labels (void)
656 {
657 gcc_assert (edge_to_cases == NULL);
658
659 edge_to_cases = htab_create (37,
660 edge_to_cases_hash,
661 edge_to_cases_eq,
662 edge_to_cases_cleanup);
663 }
664
665 /* Return nonzero if we are recording information for case labels. */
666
667 static bool
recording_case_labels_p(void)668 recording_case_labels_p (void)
669 {
670 return (edge_to_cases != NULL);
671 }
672
673 /* Stop recording information mapping edges to case labels and
674 remove any information we have recorded. */
675 void
end_recording_case_labels(void)676 end_recording_case_labels (void)
677 {
678 htab_delete (edge_to_cases);
679 edge_to_cases = NULL;
680 }
681
682 /* Record that CASE_LABEL (a CASE_LABEL_EXPR) references edge E. */
683
684 static void
record_switch_edge(edge e,tree case_label)685 record_switch_edge (edge e, tree case_label)
686 {
687 struct edge_to_cases_elt *elt;
688 void **slot;
689
690 /* Build a hash table element so we can see if E is already
691 in the table. */
692 elt = xmalloc (sizeof (struct edge_to_cases_elt));
693 elt->e = e;
694 elt->case_labels = case_label;
695
696 slot = htab_find_slot (edge_to_cases, elt, INSERT);
697
698 if (*slot == NULL)
699 {
700 /* E was not in the hash table. Install E into the hash table. */
701 *slot = (void *)elt;
702 }
703 else
704 {
705 /* E was already in the hash table. Free ELT as we do not need it
706 anymore. */
707 free (elt);
708
709 /* Get the entry stored in the hash table. */
710 elt = (struct edge_to_cases_elt *) *slot;
711
712 /* Add it to the chain of CASE_LABEL_EXPRs referencing E. */
713 TREE_CHAIN (case_label) = elt->case_labels;
714 elt->case_labels = case_label;
715 }
716 }
717
718 /* If we are inside a {start,end}_recording_cases block, then return
719 a chain of CASE_LABEL_EXPRs from T which reference E.
720
721 Otherwise return NULL. */
722
723 static tree
get_cases_for_edge(edge e,tree t)724 get_cases_for_edge (edge e, tree t)
725 {
726 struct edge_to_cases_elt elt, *elt_p;
727 void **slot;
728 size_t i, n;
729 tree vec;
730
731 /* If we are not recording cases, then we do not have CASE_LABEL_EXPR
732 chains available. Return NULL so the caller can detect this case. */
733 if (!recording_case_labels_p ())
734 return NULL;
735
736 restart:
737 elt.e = e;
738 elt.case_labels = NULL;
739 slot = htab_find_slot (edge_to_cases, &elt, NO_INSERT);
740
741 if (slot)
742 {
743 elt_p = (struct edge_to_cases_elt *)*slot;
744 return elt_p->case_labels;
745 }
746
747 /* If we did not find E in the hash table, then this must be the first
748 time we have been queried for information about E & T. Add all the
749 elements from T to the hash table then perform the query again. */
750
751 vec = SWITCH_LABELS (t);
752 n = TREE_VEC_LENGTH (vec);
753 for (i = 0; i < n; i++)
754 {
755 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
756 basic_block label_bb = label_to_block (lab);
757 record_switch_edge (find_edge (e->src, label_bb), TREE_VEC_ELT (vec, i));
758 }
759 goto restart;
760 }
761
762 /* Create the edges for a SWITCH_EXPR starting at block BB.
763 At this point, the switch body has been lowered and the
764 SWITCH_LABELS filled in, so this is in effect a multi-way branch. */
765
766 static void
make_switch_expr_edges(basic_block bb)767 make_switch_expr_edges (basic_block bb)
768 {
769 tree entry = last_stmt (bb);
770 size_t i, n;
771 tree vec;
772
773 vec = SWITCH_LABELS (entry);
774 n = TREE_VEC_LENGTH (vec);
775
776 for (i = 0; i < n; ++i)
777 {
778 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
779 basic_block label_bb = label_to_block (lab);
780 make_edge (bb, label_bb, 0);
781 }
782 }
783
784
785 /* Return the basic block holding label DEST. */
786
787 basic_block
label_to_block_fn(struct function * ifun,tree dest)788 label_to_block_fn (struct function *ifun, tree dest)
789 {
790 int uid = LABEL_DECL_UID (dest);
791
792 /* We would die hard when faced by an undefined label. Emit a label to
793 the very first basic block. This will hopefully make even the dataflow
794 and undefined variable warnings quite right. */
795 if ((errorcount || sorrycount) && uid < 0)
796 {
797 block_stmt_iterator bsi = bsi_start (BASIC_BLOCK (0));
798 tree stmt;
799
800 stmt = build1 (LABEL_EXPR, void_type_node, dest);
801 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
802 uid = LABEL_DECL_UID (dest);
803 }
804 if (VARRAY_SIZE (ifun->cfg->x_label_to_block_map) <= (unsigned int)uid)
805 return NULL;
806 return VARRAY_BB (ifun->cfg->x_label_to_block_map, uid);
807 }
808
809 /* Create edges for a goto statement at block BB. */
810
811 static void
make_goto_expr_edges(basic_block bb)812 make_goto_expr_edges (basic_block bb)
813 {
814 tree goto_t;
815 basic_block target_bb;
816 int for_call;
817 block_stmt_iterator last = bsi_last (bb);
818
819 goto_t = bsi_stmt (last);
820
821 /* If the last statement is not a GOTO (i.e., it is a RETURN_EXPR,
822 CALL_EXPR or MODIFY_EXPR), then the edge is an abnormal edge resulting
823 from a nonlocal goto. */
824 if (TREE_CODE (goto_t) != GOTO_EXPR)
825 for_call = 1;
826 else
827 {
828 tree dest = GOTO_DESTINATION (goto_t);
829 for_call = 0;
830
831 /* A GOTO to a local label creates normal edges. */
832 if (simple_goto_p (goto_t))
833 {
834 edge e = make_edge (bb, label_to_block (dest), EDGE_FALLTHRU);
835 #ifdef USE_MAPPED_LOCATION
836 e->goto_locus = EXPR_LOCATION (goto_t);
837 #else
838 e->goto_locus = EXPR_LOCUS (goto_t);
839 #endif
840 bsi_remove (&last);
841 return;
842 }
843
844 /* Nothing more to do for nonlocal gotos. */
845 if (TREE_CODE (dest) == LABEL_DECL)
846 return;
847
848 /* Computed gotos remain. */
849 }
850
851 /* Look for the block starting with the destination label. In the
852 case of a computed goto, make an edge to any label block we find
853 in the CFG. */
854 FOR_EACH_BB (target_bb)
855 {
856 block_stmt_iterator bsi;
857
858 for (bsi = bsi_start (target_bb); !bsi_end_p (bsi); bsi_next (&bsi))
859 {
860 tree target = bsi_stmt (bsi);
861
862 if (TREE_CODE (target) != LABEL_EXPR)
863 break;
864
865 if (
866 /* Computed GOTOs. Make an edge to every label block that has
867 been marked as a potential target for a computed goto. */
868 (FORCED_LABEL (LABEL_EXPR_LABEL (target)) && for_call == 0)
869 /* Nonlocal GOTO target. Make an edge to every label block
870 that has been marked as a potential target for a nonlocal
871 goto. */
872 || (DECL_NONLOCAL (LABEL_EXPR_LABEL (target)) && for_call == 1))
873 {
874 make_edge (bb, target_bb, EDGE_ABNORMAL);
875 break;
876 }
877 }
878 }
879
880 /* Degenerate case of computed goto with no labels. */
881 if (!for_call && EDGE_COUNT (bb->succs) == 0)
882 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
883 }
884
885
886 /*---------------------------------------------------------------------------
887 Flowgraph analysis
888 ---------------------------------------------------------------------------*/
889
890 /* Cleanup useless labels in basic blocks. This is something we wish
891 to do early because it allows us to group case labels before creating
892 the edges for the CFG, and it speeds up block statement iterators in
893 all passes later on.
894 We only run this pass once, running it more than once is probably not
895 profitable. */
896
897 /* A map from basic block index to the leading label of that block. */
898 static tree *label_for_bb;
899
900 /* Callback for for_each_eh_region. Helper for cleanup_dead_labels. */
901 static void
update_eh_label(struct eh_region * region)902 update_eh_label (struct eh_region *region)
903 {
904 tree old_label = get_eh_region_tree_label (region);
905 if (old_label)
906 {
907 tree new_label;
908 basic_block bb = label_to_block (old_label);
909
910 /* ??? After optimizing, there may be EH regions with labels
911 that have already been removed from the function body, so
912 there is no basic block for them. */
913 if (! bb)
914 return;
915
916 new_label = label_for_bb[bb->index];
917 set_eh_region_tree_label (region, new_label);
918 }
919 }
920
921 /* Given LABEL return the first label in the same basic block. */
922 static tree
main_block_label(tree label)923 main_block_label (tree label)
924 {
925 basic_block bb = label_to_block (label);
926
927 /* label_to_block possibly inserted undefined label into the chain. */
928 if (!label_for_bb[bb->index])
929 label_for_bb[bb->index] = label;
930 return label_for_bb[bb->index];
931 }
932
933 /* Cleanup redundant labels. This is a three-step process:
934 1) Find the leading label for each block.
935 2) Redirect all references to labels to the leading labels.
936 3) Cleanup all useless labels. */
937
938 void
cleanup_dead_labels(void)939 cleanup_dead_labels (void)
940 {
941 basic_block bb;
942 label_for_bb = xcalloc (last_basic_block, sizeof (tree));
943
944 /* Find a suitable label for each block. We use the first user-defined
945 label if there is one, or otherwise just the first label we see. */
946 FOR_EACH_BB (bb)
947 {
948 block_stmt_iterator i;
949
950 for (i = bsi_start (bb); !bsi_end_p (i); bsi_next (&i))
951 {
952 tree label, stmt = bsi_stmt (i);
953
954 if (TREE_CODE (stmt) != LABEL_EXPR)
955 break;
956
957 label = LABEL_EXPR_LABEL (stmt);
958
959 /* If we have not yet seen a label for the current block,
960 remember this one and see if there are more labels. */
961 if (! label_for_bb[bb->index])
962 {
963 label_for_bb[bb->index] = label;
964 continue;
965 }
966
967 /* If we did see a label for the current block already, but it
968 is an artificially created label, replace it if the current
969 label is a user defined label. */
970 if (! DECL_ARTIFICIAL (label)
971 && DECL_ARTIFICIAL (label_for_bb[bb->index]))
972 {
973 label_for_bb[bb->index] = label;
974 break;
975 }
976 }
977 }
978
979 /* Now redirect all jumps/branches to the selected label.
980 First do so for each block ending in a control statement. */
981 FOR_EACH_BB (bb)
982 {
983 tree stmt = last_stmt (bb);
984 if (!stmt)
985 continue;
986
987 switch (TREE_CODE (stmt))
988 {
989 case COND_EXPR:
990 {
991 tree true_branch, false_branch;
992
993 true_branch = COND_EXPR_THEN (stmt);
994 false_branch = COND_EXPR_ELSE (stmt);
995
996 GOTO_DESTINATION (true_branch)
997 = main_block_label (GOTO_DESTINATION (true_branch));
998 GOTO_DESTINATION (false_branch)
999 = main_block_label (GOTO_DESTINATION (false_branch));
1000
1001 break;
1002 }
1003
1004 case SWITCH_EXPR:
1005 {
1006 size_t i;
1007 tree vec = SWITCH_LABELS (stmt);
1008 size_t n = TREE_VEC_LENGTH (vec);
1009
1010 /* Replace all destination labels. */
1011 for (i = 0; i < n; ++i)
1012 {
1013 tree elt = TREE_VEC_ELT (vec, i);
1014 tree label = main_block_label (CASE_LABEL (elt));
1015 CASE_LABEL (elt) = label;
1016 }
1017 break;
1018 }
1019
1020 /* We have to handle GOTO_EXPRs until they're removed, and we don't
1021 remove them until after we've created the CFG edges. */
1022 case GOTO_EXPR:
1023 if (! computed_goto_p (stmt))
1024 {
1025 GOTO_DESTINATION (stmt)
1026 = main_block_label (GOTO_DESTINATION (stmt));
1027 break;
1028 }
1029
1030 default:
1031 break;
1032 }
1033 }
1034
1035 for_each_eh_region (update_eh_label);
1036
1037 /* Finally, purge dead labels. All user-defined labels and labels that
1038 can be the target of non-local gotos and labels which have their
1039 address taken are preserved. */
1040 FOR_EACH_BB (bb)
1041 {
1042 block_stmt_iterator i;
1043 tree label_for_this_bb = label_for_bb[bb->index];
1044
1045 if (! label_for_this_bb)
1046 continue;
1047
1048 for (i = bsi_start (bb); !bsi_end_p (i); )
1049 {
1050 tree label, stmt = bsi_stmt (i);
1051
1052 if (TREE_CODE (stmt) != LABEL_EXPR)
1053 break;
1054
1055 label = LABEL_EXPR_LABEL (stmt);
1056
1057 if (label == label_for_this_bb
1058 || ! DECL_ARTIFICIAL (label)
1059 || DECL_NONLOCAL (label)
1060 || FORCED_LABEL (label))
1061 bsi_next (&i);
1062 else
1063 bsi_remove (&i);
1064 }
1065 }
1066
1067 free (label_for_bb);
1068 }
1069
1070 /* Look for blocks ending in a multiway branch (a SWITCH_EXPR in GIMPLE),
1071 and scan the sorted vector of cases. Combine the ones jumping to the
1072 same label.
1073 Eg. three separate entries 1: 2: 3: become one entry 1..3: */
1074
1075 void
group_case_labels(void)1076 group_case_labels (void)
1077 {
1078 basic_block bb;
1079
1080 FOR_EACH_BB (bb)
1081 {
1082 tree stmt = last_stmt (bb);
1083 if (stmt && TREE_CODE (stmt) == SWITCH_EXPR)
1084 {
1085 tree labels = SWITCH_LABELS (stmt);
1086 int old_size = TREE_VEC_LENGTH (labels);
1087 int i, j, new_size = old_size;
1088 tree default_case = TREE_VEC_ELT (labels, old_size - 1);
1089 tree default_label;
1090
1091 /* The default label is always the last case in a switch
1092 statement after gimplification. */
1093 default_label = CASE_LABEL (default_case);
1094
1095 /* Look for possible opportunities to merge cases.
1096 Ignore the last element of the label vector because it
1097 must be the default case. */
1098 i = 0;
1099 while (i < old_size - 1)
1100 {
1101 tree base_case, base_label, base_high;
1102 base_case = TREE_VEC_ELT (labels, i);
1103
1104 gcc_assert (base_case);
1105 base_label = CASE_LABEL (base_case);
1106
1107 /* Discard cases that have the same destination as the
1108 default case. */
1109 if (base_label == default_label)
1110 {
1111 TREE_VEC_ELT (labels, i) = NULL_TREE;
1112 i++;
1113 new_size--;
1114 continue;
1115 }
1116
1117 base_high = CASE_HIGH (base_case) ?
1118 CASE_HIGH (base_case) : CASE_LOW (base_case);
1119 i++;
1120 /* Try to merge case labels. Break out when we reach the end
1121 of the label vector or when we cannot merge the next case
1122 label with the current one. */
1123 while (i < old_size - 1)
1124 {
1125 tree merge_case = TREE_VEC_ELT (labels, i);
1126 tree merge_label = CASE_LABEL (merge_case);
1127 tree t = int_const_binop (PLUS_EXPR, base_high,
1128 integer_one_node, 1);
1129
1130 /* Merge the cases if they jump to the same place,
1131 and their ranges are consecutive. */
1132 if (merge_label == base_label
1133 && tree_int_cst_equal (CASE_LOW (merge_case), t))
1134 {
1135 base_high = CASE_HIGH (merge_case) ?
1136 CASE_HIGH (merge_case) : CASE_LOW (merge_case);
1137 CASE_HIGH (base_case) = base_high;
1138 TREE_VEC_ELT (labels, i) = NULL_TREE;
1139 new_size--;
1140 i++;
1141 }
1142 else
1143 break;
1144 }
1145 }
1146
1147 /* Compress the case labels in the label vector, and adjust the
1148 length of the vector. */
1149 for (i = 0, j = 0; i < new_size; i++)
1150 {
1151 while (! TREE_VEC_ELT (labels, j))
1152 j++;
1153 TREE_VEC_ELT (labels, i) = TREE_VEC_ELT (labels, j++);
1154 }
1155 TREE_VEC_LENGTH (labels) = new_size;
1156 }
1157 }
1158 }
1159
1160 /* Checks whether we can merge block B into block A. */
1161
1162 static bool
tree_can_merge_blocks_p(basic_block a,basic_block b)1163 tree_can_merge_blocks_p (basic_block a, basic_block b)
1164 {
1165 tree stmt;
1166 block_stmt_iterator bsi;
1167 tree phi;
1168
1169 if (!single_succ_p (a))
1170 return false;
1171
1172 if (single_succ_edge (a)->flags & EDGE_ABNORMAL)
1173 return false;
1174
1175 if (single_succ (a) != b)
1176 return false;
1177
1178 if (!single_pred_p (b))
1179 return false;
1180
1181 if (b == EXIT_BLOCK_PTR)
1182 return false;
1183
1184 /* If A ends by a statement causing exceptions or something similar, we
1185 cannot merge the blocks. */
1186 stmt = last_stmt (a);
1187 if (stmt && stmt_ends_bb_p (stmt))
1188 return false;
1189
1190 /* Do not allow a block with only a non-local label to be merged. */
1191 if (stmt && TREE_CODE (stmt) == LABEL_EXPR
1192 && DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
1193 return false;
1194
1195 /* It must be possible to eliminate all phi nodes in B. If ssa form
1196 is not up-to-date, we cannot eliminate any phis. */
1197 phi = phi_nodes (b);
1198 if (phi)
1199 {
1200 if (need_ssa_update_p ())
1201 return false;
1202
1203 for (; phi; phi = PHI_CHAIN (phi))
1204 if (!is_gimple_reg (PHI_RESULT (phi))
1205 && !may_propagate_copy (PHI_RESULT (phi), PHI_ARG_DEF (phi, 0)))
1206 return false;
1207 }
1208
1209 /* Do not remove user labels. */
1210 for (bsi = bsi_start (b); !bsi_end_p (bsi); bsi_next (&bsi))
1211 {
1212 stmt = bsi_stmt (bsi);
1213 if (TREE_CODE (stmt) != LABEL_EXPR)
1214 break;
1215 if (!DECL_ARTIFICIAL (LABEL_EXPR_LABEL (stmt)))
1216 return false;
1217 }
1218
1219 /* Protect the loop latches. */
1220 if (current_loops
1221 && b->loop_father->latch == b)
1222 return false;
1223
1224 return true;
1225 }
1226
1227 /* Replaces all uses of NAME by VAL. */
1228
1229 void
replace_uses_by(tree name,tree val)1230 replace_uses_by (tree name, tree val)
1231 {
1232 imm_use_iterator imm_iter;
1233 use_operand_p use;
1234 tree stmt;
1235 edge e;
1236 unsigned i;
1237 VEC(tree,heap) *stmts = VEC_alloc (tree, heap, 20);
1238
1239 FOR_EACH_IMM_USE_SAFE (use, imm_iter, name)
1240 {
1241 stmt = USE_STMT (use);
1242 replace_exp (use, val);
1243
1244 if (TREE_CODE (stmt) == PHI_NODE)
1245 {
1246 e = PHI_ARG_EDGE (stmt, PHI_ARG_INDEX_FROM_USE (use));
1247 if (e->flags & EDGE_ABNORMAL)
1248 {
1249 /* This can only occur for virtual operands, since
1250 for the real ones SSA_NAME_OCCURS_IN_ABNORMAL_PHI (name))
1251 would prevent replacement. */
1252 gcc_assert (!is_gimple_reg (name));
1253 SSA_NAME_OCCURS_IN_ABNORMAL_PHI (val) = 1;
1254 }
1255 }
1256 else
1257 VEC_safe_push (tree, heap, stmts, stmt);
1258 }
1259
1260 /* We do not update the statements in the loop above. Consider
1261 x = w * w;
1262
1263 If we performed the update in the first loop, the statement
1264 would be rescanned after first occurrence of w is replaced,
1265 the new uses would be placed to the beginning of the list,
1266 and we would never process them. */
1267 for (i = 0; VEC_iterate (tree, stmts, i, stmt); i++)
1268 {
1269 tree rhs;
1270
1271 fold_stmt_inplace (stmt);
1272
1273 rhs = get_rhs (stmt);
1274 if (TREE_CODE (rhs) == ADDR_EXPR)
1275 recompute_tree_invarant_for_addr_expr (rhs);
1276
1277 maybe_clean_or_replace_eh_stmt (stmt, stmt);
1278 mark_new_vars_to_rename (stmt);
1279 }
1280
1281 VEC_free (tree, heap, stmts);
1282
1283 /* Also update the trees stored in loop structures. */
1284 if (current_loops)
1285 {
1286 struct loop *loop;
1287
1288 for (i = 0; i < current_loops->num; i++)
1289 {
1290 loop = current_loops->parray[i];
1291 if (loop)
1292 substitute_in_loop_info (loop, name, val);
1293 }
1294 }
1295 }
1296
1297 /* Merge block B into block A. */
1298
1299 static void
tree_merge_blocks(basic_block a,basic_block b)1300 tree_merge_blocks (basic_block a, basic_block b)
1301 {
1302 block_stmt_iterator bsi;
1303 tree_stmt_iterator last;
1304 tree phi;
1305
1306 if (dump_file)
1307 fprintf (dump_file, "Merging blocks %d and %d\n", a->index, b->index);
1308
1309 /* Remove all single-valued PHI nodes from block B of the form
1310 V_i = PHI <V_j> by propagating V_j to all the uses of V_i. */
1311 bsi = bsi_last (a);
1312 for (phi = phi_nodes (b); phi; phi = phi_nodes (b))
1313 {
1314 tree def = PHI_RESULT (phi), use = PHI_ARG_DEF (phi, 0);
1315 tree copy;
1316 bool may_replace_uses = may_propagate_copy (def, use);
1317
1318 /* In case we have loops to care about, do not propagate arguments of
1319 loop closed ssa phi nodes. */
1320 if (current_loops
1321 && is_gimple_reg (def)
1322 && TREE_CODE (use) == SSA_NAME
1323 && a->loop_father != b->loop_father)
1324 may_replace_uses = false;
1325
1326 if (!may_replace_uses)
1327 {
1328 gcc_assert (is_gimple_reg (def));
1329
1330 /* Note that just emitting the copies is fine -- there is no problem
1331 with ordering of phi nodes. This is because A is the single
1332 predecessor of B, therefore results of the phi nodes cannot
1333 appear as arguments of the phi nodes. */
1334 copy = build2 (MODIFY_EXPR, void_type_node, def, use);
1335 bsi_insert_after (&bsi, copy, BSI_NEW_STMT);
1336 SET_PHI_RESULT (phi, NULL_TREE);
1337 SSA_NAME_DEF_STMT (def) = copy;
1338 }
1339 else
1340 replace_uses_by (def, use);
1341
1342 remove_phi_node (phi, NULL);
1343 }
1344
1345 /* Ensure that B follows A. */
1346 move_block_after (b, a);
1347
1348 gcc_assert (single_succ_edge (a)->flags & EDGE_FALLTHRU);
1349 gcc_assert (!last_stmt (a) || !stmt_ends_bb_p (last_stmt (a)));
1350
1351 /* Remove labels from B and set bb_for_stmt to A for other statements. */
1352 for (bsi = bsi_start (b); !bsi_end_p (bsi);)
1353 {
1354 if (TREE_CODE (bsi_stmt (bsi)) == LABEL_EXPR)
1355 {
1356 tree label = bsi_stmt (bsi);
1357
1358 bsi_remove (&bsi);
1359 /* Now that we can thread computed gotos, we might have
1360 a situation where we have a forced label in block B
1361 However, the label at the start of block B might still be
1362 used in other ways (think about the runtime checking for
1363 Fortran assigned gotos). So we can not just delete the
1364 label. Instead we move the label to the start of block A. */
1365 if (FORCED_LABEL (LABEL_EXPR_LABEL (label)))
1366 {
1367 block_stmt_iterator dest_bsi = bsi_start (a);
1368 bsi_insert_before (&dest_bsi, label, BSI_NEW_STMT);
1369 }
1370 }
1371 else
1372 {
1373 set_bb_for_stmt (bsi_stmt (bsi), a);
1374 bsi_next (&bsi);
1375 }
1376 }
1377
1378 /* Merge the chains. */
1379 last = tsi_last (a->stmt_list);
1380 tsi_link_after (&last, b->stmt_list, TSI_NEW_STMT);
1381 b->stmt_list = NULL;
1382 }
1383
1384
1385 /* Return the one of two successors of BB that is not reachable by a
1386 reached by a complex edge, if there is one. Else, return BB. We use
1387 this in optimizations that use post-dominators for their heuristics,
1388 to catch the cases in C++ where function calls are involved. */
1389
1390 basic_block
single_noncomplex_succ(basic_block bb)1391 single_noncomplex_succ (basic_block bb)
1392 {
1393 edge e0, e1;
1394 if (EDGE_COUNT (bb->succs) != 2)
1395 return bb;
1396
1397 e0 = EDGE_SUCC (bb, 0);
1398 e1 = EDGE_SUCC (bb, 1);
1399 if (e0->flags & EDGE_COMPLEX)
1400 return e1->dest;
1401 if (e1->flags & EDGE_COMPLEX)
1402 return e0->dest;
1403
1404 return bb;
1405 }
1406
1407
1408
1409 /* Walk the function tree removing unnecessary statements.
1410
1411 * Empty statement nodes are removed
1412
1413 * Unnecessary TRY_FINALLY and TRY_CATCH blocks are removed
1414
1415 * Unnecessary COND_EXPRs are removed
1416
1417 * Some unnecessary BIND_EXPRs are removed
1418
1419 Clearly more work could be done. The trick is doing the analysis
1420 and removal fast enough to be a net improvement in compile times.
1421
1422 Note that when we remove a control structure such as a COND_EXPR
1423 BIND_EXPR, or TRY block, we will need to repeat this optimization pass
1424 to ensure we eliminate all the useless code. */
1425
1426 struct rus_data
1427 {
1428 tree *last_goto;
1429 bool repeat;
1430 bool may_throw;
1431 bool may_branch;
1432 bool has_label;
1433 };
1434
1435 static void remove_useless_stmts_1 (tree *, struct rus_data *);
1436
1437 static bool
remove_useless_stmts_warn_notreached(tree stmt)1438 remove_useless_stmts_warn_notreached (tree stmt)
1439 {
1440 if (EXPR_HAS_LOCATION (stmt))
1441 {
1442 location_t loc = EXPR_LOCATION (stmt);
1443 if (LOCATION_LINE (loc) > 0)
1444 {
1445 warning (0, "%Hwill never be executed", &loc);
1446 return true;
1447 }
1448 }
1449
1450 switch (TREE_CODE (stmt))
1451 {
1452 case STATEMENT_LIST:
1453 {
1454 tree_stmt_iterator i;
1455 for (i = tsi_start (stmt); !tsi_end_p (i); tsi_next (&i))
1456 if (remove_useless_stmts_warn_notreached (tsi_stmt (i)))
1457 return true;
1458 }
1459 break;
1460
1461 case COND_EXPR:
1462 if (remove_useless_stmts_warn_notreached (COND_EXPR_COND (stmt)))
1463 return true;
1464 if (remove_useless_stmts_warn_notreached (COND_EXPR_THEN (stmt)))
1465 return true;
1466 if (remove_useless_stmts_warn_notreached (COND_EXPR_ELSE (stmt)))
1467 return true;
1468 break;
1469
1470 case TRY_FINALLY_EXPR:
1471 case TRY_CATCH_EXPR:
1472 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt, 0)))
1473 return true;
1474 if (remove_useless_stmts_warn_notreached (TREE_OPERAND (stmt, 1)))
1475 return true;
1476 break;
1477
1478 case CATCH_EXPR:
1479 return remove_useless_stmts_warn_notreached (CATCH_BODY (stmt));
1480 case EH_FILTER_EXPR:
1481 return remove_useless_stmts_warn_notreached (EH_FILTER_FAILURE (stmt));
1482 case BIND_EXPR:
1483 return remove_useless_stmts_warn_notreached (BIND_EXPR_BLOCK (stmt));
1484
1485 default:
1486 /* Not a live container. */
1487 break;
1488 }
1489
1490 return false;
1491 }
1492
1493 static void
remove_useless_stmts_cond(tree * stmt_p,struct rus_data * data)1494 remove_useless_stmts_cond (tree *stmt_p, struct rus_data *data)
1495 {
1496 tree then_clause, else_clause, cond;
1497 bool save_has_label, then_has_label, else_has_label;
1498
1499 save_has_label = data->has_label;
1500 data->has_label = false;
1501 data->last_goto = NULL;
1502
1503 remove_useless_stmts_1 (&COND_EXPR_THEN (*stmt_p), data);
1504
1505 then_has_label = data->has_label;
1506 data->has_label = false;
1507 data->last_goto = NULL;
1508
1509 remove_useless_stmts_1 (&COND_EXPR_ELSE (*stmt_p), data);
1510
1511 else_has_label = data->has_label;
1512 data->has_label = save_has_label | then_has_label | else_has_label;
1513
1514 then_clause = COND_EXPR_THEN (*stmt_p);
1515 else_clause = COND_EXPR_ELSE (*stmt_p);
1516 cond = fold (COND_EXPR_COND (*stmt_p));
1517
1518 /* If neither arm does anything at all, we can remove the whole IF. */
1519 if (!TREE_SIDE_EFFECTS (then_clause) && !TREE_SIDE_EFFECTS (else_clause))
1520 {
1521 *stmt_p = build_empty_stmt ();
1522 data->repeat = true;
1523 }
1524
1525 /* If there are no reachable statements in an arm, then we can
1526 zap the entire conditional. */
1527 else if (integer_nonzerop (cond) && !else_has_label)
1528 {
1529 if (warn_notreached)
1530 remove_useless_stmts_warn_notreached (else_clause);
1531 *stmt_p = then_clause;
1532 data->repeat = true;
1533 }
1534 else if (integer_zerop (cond) && !then_has_label)
1535 {
1536 if (warn_notreached)
1537 remove_useless_stmts_warn_notreached (then_clause);
1538 *stmt_p = else_clause;
1539 data->repeat = true;
1540 }
1541
1542 /* Check a couple of simple things on then/else with single stmts. */
1543 else
1544 {
1545 tree then_stmt = expr_only (then_clause);
1546 tree else_stmt = expr_only (else_clause);
1547
1548 /* Notice branches to a common destination. */
1549 if (then_stmt && else_stmt
1550 && TREE_CODE (then_stmt) == GOTO_EXPR
1551 && TREE_CODE (else_stmt) == GOTO_EXPR
1552 && (GOTO_DESTINATION (then_stmt) == GOTO_DESTINATION (else_stmt)))
1553 {
1554 *stmt_p = then_stmt;
1555 data->repeat = true;
1556 }
1557
1558 /* If the THEN/ELSE clause merely assigns a value to a variable or
1559 parameter which is already known to contain that value, then
1560 remove the useless THEN/ELSE clause. */
1561 else if (TREE_CODE (cond) == VAR_DECL || TREE_CODE (cond) == PARM_DECL)
1562 {
1563 if (else_stmt
1564 && TREE_CODE (else_stmt) == MODIFY_EXPR
1565 && TREE_OPERAND (else_stmt, 0) == cond
1566 && integer_zerop (TREE_OPERAND (else_stmt, 1)))
1567 COND_EXPR_ELSE (*stmt_p) = alloc_stmt_list ();
1568 }
1569 else if ((TREE_CODE (cond) == EQ_EXPR || TREE_CODE (cond) == NE_EXPR)
1570 && (TREE_CODE (TREE_OPERAND (cond, 0)) == VAR_DECL
1571 || TREE_CODE (TREE_OPERAND (cond, 0)) == PARM_DECL)
1572 && TREE_CONSTANT (TREE_OPERAND (cond, 1)))
1573 {
1574 tree stmt = (TREE_CODE (cond) == EQ_EXPR
1575 ? then_stmt : else_stmt);
1576 tree *location = (TREE_CODE (cond) == EQ_EXPR
1577 ? &COND_EXPR_THEN (*stmt_p)
1578 : &COND_EXPR_ELSE (*stmt_p));
1579
1580 if (stmt
1581 && TREE_CODE (stmt) == MODIFY_EXPR
1582 && TREE_OPERAND (stmt, 0) == TREE_OPERAND (cond, 0)
1583 && TREE_OPERAND (stmt, 1) == TREE_OPERAND (cond, 1))
1584 *location = alloc_stmt_list ();
1585 }
1586 }
1587
1588 /* Protect GOTOs in the arm of COND_EXPRs from being removed. They
1589 would be re-introduced during lowering. */
1590 data->last_goto = NULL;
1591 }
1592
1593
1594 static void
remove_useless_stmts_tf(tree * stmt_p,struct rus_data * data)1595 remove_useless_stmts_tf (tree *stmt_p, struct rus_data *data)
1596 {
1597 bool save_may_branch, save_may_throw;
1598 bool this_may_branch, this_may_throw;
1599
1600 /* Collect may_branch and may_throw information for the body only. */
1601 save_may_branch = data->may_branch;
1602 save_may_throw = data->may_throw;
1603 data->may_branch = false;
1604 data->may_throw = false;
1605 data->last_goto = NULL;
1606
1607 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 0), data);
1608
1609 this_may_branch = data->may_branch;
1610 this_may_throw = data->may_throw;
1611 data->may_branch |= save_may_branch;
1612 data->may_throw |= save_may_throw;
1613 data->last_goto = NULL;
1614
1615 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 1), data);
1616
1617 /* If the body is empty, then we can emit the FINALLY block without
1618 the enclosing TRY_FINALLY_EXPR. */
1619 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 0)))
1620 {
1621 *stmt_p = TREE_OPERAND (*stmt_p, 1);
1622 data->repeat = true;
1623 }
1624
1625 /* If the handler is empty, then we can emit the TRY block without
1626 the enclosing TRY_FINALLY_EXPR. */
1627 else if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 1)))
1628 {
1629 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1630 data->repeat = true;
1631 }
1632
1633 /* If the body neither throws, nor branches, then we can safely
1634 string the TRY and FINALLY blocks together. */
1635 else if (!this_may_branch && !this_may_throw)
1636 {
1637 tree stmt = *stmt_p;
1638 *stmt_p = TREE_OPERAND (stmt, 0);
1639 append_to_statement_list (TREE_OPERAND (stmt, 1), stmt_p);
1640 data->repeat = true;
1641 }
1642 }
1643
1644
1645 static void
remove_useless_stmts_tc(tree * stmt_p,struct rus_data * data)1646 remove_useless_stmts_tc (tree *stmt_p, struct rus_data *data)
1647 {
1648 bool save_may_throw, this_may_throw;
1649 tree_stmt_iterator i;
1650 tree stmt;
1651
1652 /* Collect may_throw information for the body only. */
1653 save_may_throw = data->may_throw;
1654 data->may_throw = false;
1655 data->last_goto = NULL;
1656
1657 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 0), data);
1658
1659 this_may_throw = data->may_throw;
1660 data->may_throw = save_may_throw;
1661
1662 /* If the body cannot throw, then we can drop the entire TRY_CATCH_EXPR. */
1663 if (!this_may_throw)
1664 {
1665 if (warn_notreached)
1666 remove_useless_stmts_warn_notreached (TREE_OPERAND (*stmt_p, 1));
1667 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1668 data->repeat = true;
1669 return;
1670 }
1671
1672 /* Process the catch clause specially. We may be able to tell that
1673 no exceptions propagate past this point. */
1674
1675 this_may_throw = true;
1676 i = tsi_start (TREE_OPERAND (*stmt_p, 1));
1677 stmt = tsi_stmt (i);
1678 data->last_goto = NULL;
1679
1680 switch (TREE_CODE (stmt))
1681 {
1682 case CATCH_EXPR:
1683 for (; !tsi_end_p (i); tsi_next (&i))
1684 {
1685 stmt = tsi_stmt (i);
1686 /* If we catch all exceptions, then the body does not
1687 propagate exceptions past this point. */
1688 if (CATCH_TYPES (stmt) == NULL)
1689 this_may_throw = false;
1690 data->last_goto = NULL;
1691 remove_useless_stmts_1 (&CATCH_BODY (stmt), data);
1692 }
1693 break;
1694
1695 case EH_FILTER_EXPR:
1696 if (EH_FILTER_MUST_NOT_THROW (stmt))
1697 this_may_throw = false;
1698 else if (EH_FILTER_TYPES (stmt) == NULL)
1699 this_may_throw = false;
1700 remove_useless_stmts_1 (&EH_FILTER_FAILURE (stmt), data);
1701 break;
1702
1703 default:
1704 /* Otherwise this is a cleanup. */
1705 remove_useless_stmts_1 (&TREE_OPERAND (*stmt_p, 1), data);
1706
1707 /* If the cleanup is empty, then we can emit the TRY block without
1708 the enclosing TRY_CATCH_EXPR. */
1709 if (!TREE_SIDE_EFFECTS (TREE_OPERAND (*stmt_p, 1)))
1710 {
1711 *stmt_p = TREE_OPERAND (*stmt_p, 0);
1712 data->repeat = true;
1713 }
1714 break;
1715 }
1716 data->may_throw |= this_may_throw;
1717 }
1718
1719
1720 static void
remove_useless_stmts_bind(tree * stmt_p,struct rus_data * data)1721 remove_useless_stmts_bind (tree *stmt_p, struct rus_data *data)
1722 {
1723 tree block;
1724
1725 /* First remove anything underneath the BIND_EXPR. */
1726 remove_useless_stmts_1 (&BIND_EXPR_BODY (*stmt_p), data);
1727
1728 /* If the BIND_EXPR has no variables, then we can pull everything
1729 up one level and remove the BIND_EXPR, unless this is the toplevel
1730 BIND_EXPR for the current function or an inlined function.
1731
1732 When this situation occurs we will want to apply this
1733 optimization again. */
1734 block = BIND_EXPR_BLOCK (*stmt_p);
1735 if (BIND_EXPR_VARS (*stmt_p) == NULL_TREE
1736 && *stmt_p != DECL_SAVED_TREE (current_function_decl)
1737 && (! block
1738 || ! BLOCK_ABSTRACT_ORIGIN (block)
1739 || (TREE_CODE (BLOCK_ABSTRACT_ORIGIN (block))
1740 != FUNCTION_DECL)))
1741 {
1742 *stmt_p = BIND_EXPR_BODY (*stmt_p);
1743 data->repeat = true;
1744 }
1745 }
1746
1747
1748 static void
remove_useless_stmts_goto(tree * stmt_p,struct rus_data * data)1749 remove_useless_stmts_goto (tree *stmt_p, struct rus_data *data)
1750 {
1751 tree dest = GOTO_DESTINATION (*stmt_p);
1752
1753 data->may_branch = true;
1754 data->last_goto = NULL;
1755
1756 /* Record the last goto expr, so that we can delete it if unnecessary. */
1757 if (TREE_CODE (dest) == LABEL_DECL)
1758 data->last_goto = stmt_p;
1759 }
1760
1761
1762 static void
remove_useless_stmts_label(tree * stmt_p,struct rus_data * data)1763 remove_useless_stmts_label (tree *stmt_p, struct rus_data *data)
1764 {
1765 tree label = LABEL_EXPR_LABEL (*stmt_p);
1766
1767 data->has_label = true;
1768
1769 /* We do want to jump across non-local label receiver code. */
1770 if (DECL_NONLOCAL (label))
1771 data->last_goto = NULL;
1772
1773 else if (data->last_goto && GOTO_DESTINATION (*data->last_goto) == label)
1774 {
1775 *data->last_goto = build_empty_stmt ();
1776 data->repeat = true;
1777 }
1778
1779 /* ??? Add something here to delete unused labels. */
1780 }
1781
1782
1783 /* If the function is "const" or "pure", then clear TREE_SIDE_EFFECTS on its
1784 decl. This allows us to eliminate redundant or useless
1785 calls to "const" functions.
1786
1787 Gimplifier already does the same operation, but we may notice functions
1788 being const and pure once their calls has been gimplified, so we need
1789 to update the flag. */
1790
1791 static void
update_call_expr_flags(tree call)1792 update_call_expr_flags (tree call)
1793 {
1794 tree decl = get_callee_fndecl (call);
1795 if (!decl)
1796 return;
1797 if (call_expr_flags (call) & (ECF_CONST | ECF_PURE))
1798 TREE_SIDE_EFFECTS (call) = 0;
1799 if (TREE_NOTHROW (decl))
1800 TREE_NOTHROW (call) = 1;
1801 }
1802
1803
1804 /* T is CALL_EXPR. Set current_function_calls_* flags. */
1805
1806 void
notice_special_calls(tree t)1807 notice_special_calls (tree t)
1808 {
1809 int flags = call_expr_flags (t);
1810
1811 if (flags & ECF_MAY_BE_ALLOCA)
1812 current_function_calls_alloca = true;
1813 if (flags & ECF_RETURNS_TWICE)
1814 current_function_calls_setjmp = true;
1815 }
1816
1817
1818 /* Clear flags set by notice_special_calls. Used by dead code removal
1819 to update the flags. */
1820
1821 void
clear_special_calls(void)1822 clear_special_calls (void)
1823 {
1824 current_function_calls_alloca = false;
1825 current_function_calls_setjmp = false;
1826 }
1827
1828
1829 static void
remove_useless_stmts_1(tree * tp,struct rus_data * data)1830 remove_useless_stmts_1 (tree *tp, struct rus_data *data)
1831 {
1832 tree t = *tp, op;
1833
1834 switch (TREE_CODE (t))
1835 {
1836 case COND_EXPR:
1837 remove_useless_stmts_cond (tp, data);
1838 break;
1839
1840 case TRY_FINALLY_EXPR:
1841 remove_useless_stmts_tf (tp, data);
1842 break;
1843
1844 case TRY_CATCH_EXPR:
1845 remove_useless_stmts_tc (tp, data);
1846 break;
1847
1848 case BIND_EXPR:
1849 remove_useless_stmts_bind (tp, data);
1850 break;
1851
1852 case GOTO_EXPR:
1853 remove_useless_stmts_goto (tp, data);
1854 break;
1855
1856 case LABEL_EXPR:
1857 remove_useless_stmts_label (tp, data);
1858 break;
1859
1860 case RETURN_EXPR:
1861 fold_stmt (tp);
1862 data->last_goto = NULL;
1863 data->may_branch = true;
1864 break;
1865
1866 case CALL_EXPR:
1867 fold_stmt (tp);
1868 data->last_goto = NULL;
1869 notice_special_calls (t);
1870 update_call_expr_flags (t);
1871 if (tree_could_throw_p (t))
1872 data->may_throw = true;
1873 break;
1874
1875 case MODIFY_EXPR:
1876 data->last_goto = NULL;
1877 fold_stmt (tp);
1878 op = get_call_expr_in (t);
1879 if (op)
1880 {
1881 update_call_expr_flags (op);
1882 notice_special_calls (op);
1883 }
1884 if (tree_could_throw_p (t))
1885 data->may_throw = true;
1886 break;
1887
1888 case STATEMENT_LIST:
1889 {
1890 tree_stmt_iterator i = tsi_start (t);
1891 while (!tsi_end_p (i))
1892 {
1893 t = tsi_stmt (i);
1894 if (IS_EMPTY_STMT (t))
1895 {
1896 tsi_delink (&i);
1897 continue;
1898 }
1899
1900 remove_useless_stmts_1 (tsi_stmt_ptr (i), data);
1901
1902 t = tsi_stmt (i);
1903 if (TREE_CODE (t) == STATEMENT_LIST)
1904 {
1905 tsi_link_before (&i, t, TSI_SAME_STMT);
1906 tsi_delink (&i);
1907 }
1908 else
1909 tsi_next (&i);
1910 }
1911 }
1912 break;
1913 case ASM_EXPR:
1914 fold_stmt (tp);
1915 data->last_goto = NULL;
1916 break;
1917
1918 default:
1919 data->last_goto = NULL;
1920 break;
1921 }
1922 }
1923
1924 static void
remove_useless_stmts(void)1925 remove_useless_stmts (void)
1926 {
1927 struct rus_data data;
1928
1929 clear_special_calls ();
1930
1931 do
1932 {
1933 memset (&data, 0, sizeof (data));
1934 remove_useless_stmts_1 (&DECL_SAVED_TREE (current_function_decl), &data);
1935 }
1936 while (data.repeat);
1937 }
1938
1939
1940 struct tree_opt_pass pass_remove_useless_stmts =
1941 {
1942 "useless", /* name */
1943 NULL, /* gate */
1944 remove_useless_stmts, /* execute */
1945 NULL, /* sub */
1946 NULL, /* next */
1947 0, /* static_pass_number */
1948 0, /* tv_id */
1949 PROP_gimple_any, /* properties_required */
1950 0, /* properties_provided */
1951 0, /* properties_destroyed */
1952 0, /* todo_flags_start */
1953 TODO_dump_func, /* todo_flags_finish */
1954 0 /* letter */
1955 };
1956
1957 /* Remove PHI nodes associated with basic block BB and all edges out of BB. */
1958
1959 static void
remove_phi_nodes_and_edges_for_unreachable_block(basic_block bb)1960 remove_phi_nodes_and_edges_for_unreachable_block (basic_block bb)
1961 {
1962 tree phi;
1963
1964 /* Since this block is no longer reachable, we can just delete all
1965 of its PHI nodes. */
1966 phi = phi_nodes (bb);
1967 while (phi)
1968 {
1969 tree next = PHI_CHAIN (phi);
1970 remove_phi_node (phi, NULL_TREE);
1971 phi = next;
1972 }
1973
1974 /* Remove edges to BB's successors. */
1975 while (EDGE_COUNT (bb->succs) > 0)
1976 remove_edge (EDGE_SUCC (bb, 0));
1977 }
1978
1979
1980 /* Remove statements of basic block BB. */
1981
1982 static void
remove_bb(basic_block bb)1983 remove_bb (basic_block bb)
1984 {
1985 block_stmt_iterator i;
1986 #ifdef USE_MAPPED_LOCATION
1987 source_location loc = UNKNOWN_LOCATION;
1988 #else
1989 source_locus loc = 0;
1990 #endif
1991
1992 if (dump_file)
1993 {
1994 fprintf (dump_file, "Removing basic block %d\n", bb->index);
1995 if (dump_flags & TDF_DETAILS)
1996 {
1997 dump_bb (bb, dump_file, 0);
1998 fprintf (dump_file, "\n");
1999 }
2000 }
2001
2002 /* If we remove the header or the latch of a loop, mark the loop for
2003 removal by setting its header and latch to NULL. */
2004 if (current_loops)
2005 {
2006 struct loop *loop = bb->loop_father;
2007
2008 if (loop->latch == bb
2009 || loop->header == bb)
2010 {
2011 loop->latch = NULL;
2012 loop->header = NULL;
2013
2014 /* Also clean up the information associated with the loop. Updating
2015 it would waste time. More importantly, it may refer to ssa
2016 names that were defined in other removed basic block -- these
2017 ssa names are now removed and invalid. */
2018 free_numbers_of_iterations_estimates_loop (loop);
2019 }
2020 }
2021
2022 /* Remove all the instructions in the block. */
2023 for (i = bsi_start (bb); !bsi_end_p (i);)
2024 {
2025 tree stmt = bsi_stmt (i);
2026 if (TREE_CODE (stmt) == LABEL_EXPR
2027 && (FORCED_LABEL (LABEL_EXPR_LABEL (stmt))
2028 || DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt))))
2029 {
2030 basic_block new_bb;
2031 block_stmt_iterator new_bsi;
2032
2033 /* A non-reachable non-local label may still be referenced.
2034 But it no longer needs to carry the extra semantics of
2035 non-locality. */
2036 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
2037 {
2038 DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)) = 0;
2039 FORCED_LABEL (LABEL_EXPR_LABEL (stmt)) = 1;
2040 }
2041
2042 new_bb = bb->prev_bb;
2043 new_bsi = bsi_start (new_bb);
2044 bsi_remove (&i);
2045 bsi_insert_before (&new_bsi, stmt, BSI_NEW_STMT);
2046 }
2047 else
2048 {
2049 /* Release SSA definitions if we are in SSA. Note that we
2050 may be called when not in SSA. For example,
2051 final_cleanup calls this function via
2052 cleanup_tree_cfg. */
2053 if (in_ssa_p)
2054 release_defs (stmt);
2055
2056 bsi_remove (&i);
2057 }
2058
2059 /* Don't warn for removed gotos. Gotos are often removed due to
2060 jump threading, thus resulting in bogus warnings. Not great,
2061 since this way we lose warnings for gotos in the original
2062 program that are indeed unreachable. */
2063 if (TREE_CODE (stmt) != GOTO_EXPR && EXPR_HAS_LOCATION (stmt) && !loc)
2064 {
2065 #ifdef USE_MAPPED_LOCATION
2066 if (EXPR_HAS_LOCATION (stmt))
2067 loc = EXPR_LOCATION (stmt);
2068 #else
2069 source_locus t;
2070 t = EXPR_LOCUS (stmt);
2071 if (t && LOCATION_LINE (*t) > 0)
2072 loc = t;
2073 #endif
2074 }
2075 }
2076
2077 /* If requested, give a warning that the first statement in the
2078 block is unreachable. We walk statements backwards in the
2079 loop above, so the last statement we process is the first statement
2080 in the block. */
2081 #ifdef USE_MAPPED_LOCATION
2082 if (loc > BUILTINS_LOCATION)
2083 warning (OPT_Wunreachable_code, "%Hwill never be executed", &loc);
2084 #else
2085 if (loc)
2086 warning (OPT_Wunreachable_code, "%Hwill never be executed", loc);
2087 #endif
2088
2089 remove_phi_nodes_and_edges_for_unreachable_block (bb);
2090 }
2091
2092
2093 /* Given a basic block BB ending with COND_EXPR or SWITCH_EXPR, and a
2094 predicate VAL, return the edge that will be taken out of the block.
2095 If VAL does not match a unique edge, NULL is returned. */
2096
2097 edge
find_taken_edge(basic_block bb,tree val)2098 find_taken_edge (basic_block bb, tree val)
2099 {
2100 tree stmt;
2101
2102 stmt = last_stmt (bb);
2103
2104 gcc_assert (stmt);
2105 gcc_assert (is_ctrl_stmt (stmt));
2106 gcc_assert (val);
2107
2108 if (! is_gimple_min_invariant (val))
2109 return NULL;
2110
2111 if (TREE_CODE (stmt) == COND_EXPR)
2112 return find_taken_edge_cond_expr (bb, val);
2113
2114 if (TREE_CODE (stmt) == SWITCH_EXPR)
2115 return find_taken_edge_switch_expr (bb, val);
2116
2117 if (computed_goto_p (stmt))
2118 return find_taken_edge_computed_goto (bb, TREE_OPERAND( val, 0));
2119
2120 gcc_unreachable ();
2121 }
2122
2123 /* Given a constant value VAL and the entry block BB to a GOTO_EXPR
2124 statement, determine which of the outgoing edges will be taken out of the
2125 block. Return NULL if either edge may be taken. */
2126
2127 static edge
find_taken_edge_computed_goto(basic_block bb,tree val)2128 find_taken_edge_computed_goto (basic_block bb, tree val)
2129 {
2130 basic_block dest;
2131 edge e = NULL;
2132
2133 dest = label_to_block (val);
2134 if (dest)
2135 {
2136 e = find_edge (bb, dest);
2137 gcc_assert (e != NULL);
2138 }
2139
2140 return e;
2141 }
2142
2143 /* Given a constant value VAL and the entry block BB to a COND_EXPR
2144 statement, determine which of the two edges will be taken out of the
2145 block. Return NULL if either edge may be taken. */
2146
2147 static edge
find_taken_edge_cond_expr(basic_block bb,tree val)2148 find_taken_edge_cond_expr (basic_block bb, tree val)
2149 {
2150 edge true_edge, false_edge;
2151
2152 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
2153
2154 gcc_assert (TREE_CODE (val) == INTEGER_CST);
2155 return (zero_p (val) ? false_edge : true_edge);
2156 }
2157
2158 /* Given an INTEGER_CST VAL and the entry block BB to a SWITCH_EXPR
2159 statement, determine which edge will be taken out of the block. Return
2160 NULL if any edge may be taken. */
2161
2162 static edge
find_taken_edge_switch_expr(basic_block bb,tree val)2163 find_taken_edge_switch_expr (basic_block bb, tree val)
2164 {
2165 tree switch_expr, taken_case;
2166 basic_block dest_bb;
2167 edge e;
2168
2169 switch_expr = last_stmt (bb);
2170 taken_case = find_case_label_for_value (switch_expr, val);
2171 dest_bb = label_to_block (CASE_LABEL (taken_case));
2172
2173 e = find_edge (bb, dest_bb);
2174 gcc_assert (e);
2175 return e;
2176 }
2177
2178
2179 /* Return the CASE_LABEL_EXPR that SWITCH_EXPR will take for VAL.
2180 We can make optimal use here of the fact that the case labels are
2181 sorted: We can do a binary search for a case matching VAL. */
2182
2183 static tree
find_case_label_for_value(tree switch_expr,tree val)2184 find_case_label_for_value (tree switch_expr, tree val)
2185 {
2186 tree vec = SWITCH_LABELS (switch_expr);
2187 size_t low, high, n = TREE_VEC_LENGTH (vec);
2188 tree default_case = TREE_VEC_ELT (vec, n - 1);
2189
2190 for (low = -1, high = n - 1; high - low > 1; )
2191 {
2192 size_t i = (high + low) / 2;
2193 tree t = TREE_VEC_ELT (vec, i);
2194 int cmp;
2195
2196 /* Cache the result of comparing CASE_LOW and val. */
2197 cmp = tree_int_cst_compare (CASE_LOW (t), val);
2198
2199 if (cmp > 0)
2200 high = i;
2201 else
2202 low = i;
2203
2204 if (CASE_HIGH (t) == NULL)
2205 {
2206 /* A singe-valued case label. */
2207 if (cmp == 0)
2208 return t;
2209 }
2210 else
2211 {
2212 /* A case range. We can only handle integer ranges. */
2213 if (cmp <= 0 && tree_int_cst_compare (CASE_HIGH (t), val) >= 0)
2214 return t;
2215 }
2216 }
2217
2218 return default_case;
2219 }
2220
2221
2222
2223
2224 /*---------------------------------------------------------------------------
2225 Debugging functions
2226 ---------------------------------------------------------------------------*/
2227
2228 /* Dump tree-specific information of block BB to file OUTF. */
2229
2230 void
tree_dump_bb(basic_block bb,FILE * outf,int indent)2231 tree_dump_bb (basic_block bb, FILE *outf, int indent)
2232 {
2233 dump_generic_bb (outf, bb, indent, TDF_VOPS);
2234 }
2235
2236
2237 /* Dump a basic block on stderr. */
2238
2239 void
debug_tree_bb(basic_block bb)2240 debug_tree_bb (basic_block bb)
2241 {
2242 dump_bb (bb, stderr, 0);
2243 }
2244
2245
2246 /* Dump basic block with index N on stderr. */
2247
2248 basic_block
debug_tree_bb_n(int n)2249 debug_tree_bb_n (int n)
2250 {
2251 debug_tree_bb (BASIC_BLOCK (n));
2252 return BASIC_BLOCK (n);
2253 }
2254
2255
2256 /* Dump the CFG on stderr.
2257
2258 FLAGS are the same used by the tree dumping functions
2259 (see TDF_* in tree.h). */
2260
2261 void
debug_tree_cfg(int flags)2262 debug_tree_cfg (int flags)
2263 {
2264 dump_tree_cfg (stderr, flags);
2265 }
2266
2267
2268 /* Dump the program showing basic block boundaries on the given FILE.
2269
2270 FLAGS are the same used by the tree dumping functions (see TDF_* in
2271 tree.h). */
2272
2273 void
dump_tree_cfg(FILE * file,int flags)2274 dump_tree_cfg (FILE *file, int flags)
2275 {
2276 if (flags & TDF_DETAILS)
2277 {
2278 const char *funcname
2279 = lang_hooks.decl_printable_name (current_function_decl, 2);
2280
2281 fputc ('\n', file);
2282 fprintf (file, ";; Function %s\n\n", funcname);
2283 fprintf (file, ";; \n%d basic blocks, %d edges, last basic block %d.\n\n",
2284 n_basic_blocks, n_edges, last_basic_block);
2285
2286 brief_dump_cfg (file);
2287 fprintf (file, "\n");
2288 }
2289
2290 if (flags & TDF_STATS)
2291 dump_cfg_stats (file);
2292
2293 dump_function_to_file (current_function_decl, file, flags | TDF_BLOCKS);
2294 }
2295
2296
2297 /* Dump CFG statistics on FILE. */
2298
2299 void
dump_cfg_stats(FILE * file)2300 dump_cfg_stats (FILE *file)
2301 {
2302 static long max_num_merged_labels = 0;
2303 unsigned long size, total = 0;
2304 long num_edges;
2305 basic_block bb;
2306 const char * const fmt_str = "%-30s%-13s%12s\n";
2307 const char * const fmt_str_1 = "%-30s%13d%11lu%c\n";
2308 const char * const fmt_str_2 = "%-30s%13ld%11lu%c\n";
2309 const char * const fmt_str_3 = "%-43s%11lu%c\n";
2310 const char *funcname
2311 = lang_hooks.decl_printable_name (current_function_decl, 2);
2312
2313
2314 fprintf (file, "\nCFG Statistics for %s\n\n", funcname);
2315
2316 fprintf (file, "---------------------------------------------------------\n");
2317 fprintf (file, fmt_str, "", " Number of ", "Memory");
2318 fprintf (file, fmt_str, "", " instances ", "used ");
2319 fprintf (file, "---------------------------------------------------------\n");
2320
2321 size = n_basic_blocks * sizeof (struct basic_block_def);
2322 total += size;
2323 fprintf (file, fmt_str_1, "Basic blocks", n_basic_blocks,
2324 SCALE (size), LABEL (size));
2325
2326 num_edges = 0;
2327 FOR_EACH_BB (bb)
2328 num_edges += EDGE_COUNT (bb->succs);
2329 size = num_edges * sizeof (struct edge_def);
2330 total += size;
2331 fprintf (file, fmt_str_2, "Edges", num_edges, SCALE (size), LABEL (size));
2332
2333 fprintf (file, "---------------------------------------------------------\n");
2334 fprintf (file, fmt_str_3, "Total memory used by CFG data", SCALE (total),
2335 LABEL (total));
2336 fprintf (file, "---------------------------------------------------------\n");
2337 fprintf (file, "\n");
2338
2339 if (cfg_stats.num_merged_labels > max_num_merged_labels)
2340 max_num_merged_labels = cfg_stats.num_merged_labels;
2341
2342 fprintf (file, "Coalesced label blocks: %ld (Max so far: %ld)\n",
2343 cfg_stats.num_merged_labels, max_num_merged_labels);
2344
2345 fprintf (file, "\n");
2346 }
2347
2348
2349 /* Dump CFG statistics on stderr. Keep extern so that it's always
2350 linked in the final executable. */
2351
2352 void
debug_cfg_stats(void)2353 debug_cfg_stats (void)
2354 {
2355 dump_cfg_stats (stderr);
2356 }
2357
2358
2359 /* Dump the flowgraph to a .vcg FILE. */
2360
2361 static void
tree_cfg2vcg(FILE * file)2362 tree_cfg2vcg (FILE *file)
2363 {
2364 edge e;
2365 edge_iterator ei;
2366 basic_block bb;
2367 const char *funcname
2368 = lang_hooks.decl_printable_name (current_function_decl, 2);
2369
2370 /* Write the file header. */
2371 fprintf (file, "graph: { title: \"%s\"\n", funcname);
2372 fprintf (file, "node: { title: \"ENTRY\" label: \"ENTRY\" }\n");
2373 fprintf (file, "node: { title: \"EXIT\" label: \"EXIT\" }\n");
2374
2375 /* Write blocks and edges. */
2376 FOR_EACH_EDGE (e, ei, ENTRY_BLOCK_PTR->succs)
2377 {
2378 fprintf (file, "edge: { sourcename: \"ENTRY\" targetname: \"%d\"",
2379 e->dest->index);
2380
2381 if (e->flags & EDGE_FAKE)
2382 fprintf (file, " linestyle: dotted priority: 10");
2383 else
2384 fprintf (file, " linestyle: solid priority: 100");
2385
2386 fprintf (file, " }\n");
2387 }
2388 fputc ('\n', file);
2389
2390 FOR_EACH_BB (bb)
2391 {
2392 enum tree_code head_code, end_code;
2393 const char *head_name, *end_name;
2394 int head_line = 0;
2395 int end_line = 0;
2396 tree first = first_stmt (bb);
2397 tree last = last_stmt (bb);
2398
2399 if (first)
2400 {
2401 head_code = TREE_CODE (first);
2402 head_name = tree_code_name[head_code];
2403 head_line = get_lineno (first);
2404 }
2405 else
2406 head_name = "no-statement";
2407
2408 if (last)
2409 {
2410 end_code = TREE_CODE (last);
2411 end_name = tree_code_name[end_code];
2412 end_line = get_lineno (last);
2413 }
2414 else
2415 end_name = "no-statement";
2416
2417 fprintf (file, "node: { title: \"%d\" label: \"#%d\\n%s (%d)\\n%s (%d)\"}\n",
2418 bb->index, bb->index, head_name, head_line, end_name,
2419 end_line);
2420
2421 FOR_EACH_EDGE (e, ei, bb->succs)
2422 {
2423 if (e->dest == EXIT_BLOCK_PTR)
2424 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"EXIT\"", bb->index);
2425 else
2426 fprintf (file, "edge: { sourcename: \"%d\" targetname: \"%d\"", bb->index, e->dest->index);
2427
2428 if (e->flags & EDGE_FAKE)
2429 fprintf (file, " priority: 10 linestyle: dotted");
2430 else
2431 fprintf (file, " priority: 100 linestyle: solid");
2432
2433 fprintf (file, " }\n");
2434 }
2435
2436 if (bb->next_bb != EXIT_BLOCK_PTR)
2437 fputc ('\n', file);
2438 }
2439
2440 fputs ("}\n\n", file);
2441 }
2442
2443
2444
2445 /*---------------------------------------------------------------------------
2446 Miscellaneous helpers
2447 ---------------------------------------------------------------------------*/
2448
2449 /* Return true if T represents a stmt that always transfers control. */
2450
2451 bool
is_ctrl_stmt(tree t)2452 is_ctrl_stmt (tree t)
2453 {
2454 return (TREE_CODE (t) == COND_EXPR
2455 || TREE_CODE (t) == SWITCH_EXPR
2456 || TREE_CODE (t) == GOTO_EXPR
2457 || TREE_CODE (t) == RETURN_EXPR
2458 || TREE_CODE (t) == RESX_EXPR);
2459 }
2460
2461
2462 /* Return true if T is a statement that may alter the flow of control
2463 (e.g., a call to a non-returning function). */
2464
2465 bool
is_ctrl_altering_stmt(tree t)2466 is_ctrl_altering_stmt (tree t)
2467 {
2468 tree call;
2469
2470 gcc_assert (t);
2471 call = get_call_expr_in (t);
2472 if (call)
2473 {
2474 /* A non-pure/const CALL_EXPR alters flow control if the current
2475 function has nonlocal labels. */
2476 if (TREE_SIDE_EFFECTS (call) && current_function_has_nonlocal_label)
2477 return true;
2478
2479 /* A CALL_EXPR also alters control flow if it does not return. */
2480 if (call_expr_flags (call) & ECF_NORETURN)
2481 return true;
2482 }
2483
2484 /* If a statement can throw, it alters control flow. */
2485 return tree_can_throw_internal (t);
2486 }
2487
2488
2489 /* Return true if T is a computed goto. */
2490
2491 bool
computed_goto_p(tree t)2492 computed_goto_p (tree t)
2493 {
2494 return (TREE_CODE (t) == GOTO_EXPR
2495 && TREE_CODE (GOTO_DESTINATION (t)) != LABEL_DECL);
2496 }
2497
2498
2499 /* Checks whether EXPR is a simple local goto. */
2500
2501 bool
simple_goto_p(tree expr)2502 simple_goto_p (tree expr)
2503 {
2504 return (TREE_CODE (expr) == GOTO_EXPR
2505 && TREE_CODE (GOTO_DESTINATION (expr)) == LABEL_DECL);
2506 }
2507
2508
2509 /* Return true if T should start a new basic block. PREV_T is the
2510 statement preceding T. It is used when T is a label or a case label.
2511 Labels should only start a new basic block if their previous statement
2512 wasn't a label. Otherwise, sequence of labels would generate
2513 unnecessary basic blocks that only contain a single label. */
2514
2515 static inline bool
stmt_starts_bb_p(tree t,tree prev_t)2516 stmt_starts_bb_p (tree t, tree prev_t)
2517 {
2518 if (t == NULL_TREE)
2519 return false;
2520
2521 /* LABEL_EXPRs start a new basic block only if the preceding
2522 statement wasn't a label of the same type. This prevents the
2523 creation of consecutive blocks that have nothing but a single
2524 label. */
2525 if (TREE_CODE (t) == LABEL_EXPR)
2526 {
2527 /* Nonlocal and computed GOTO targets always start a new block. */
2528 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (t))
2529 || FORCED_LABEL (LABEL_EXPR_LABEL (t)))
2530 return true;
2531
2532 if (prev_t && TREE_CODE (prev_t) == LABEL_EXPR)
2533 {
2534 if (DECL_NONLOCAL (LABEL_EXPR_LABEL (prev_t)))
2535 return true;
2536
2537 cfg_stats.num_merged_labels++;
2538 return false;
2539 }
2540 else
2541 return true;
2542 }
2543
2544 return false;
2545 }
2546
2547
2548 /* Return true if T should end a basic block. */
2549
2550 bool
stmt_ends_bb_p(tree t)2551 stmt_ends_bb_p (tree t)
2552 {
2553 return is_ctrl_stmt (t) || is_ctrl_altering_stmt (t);
2554 }
2555
2556
2557 /* Add gotos that used to be represented implicitly in the CFG. */
2558
2559 void
disband_implicit_edges(void)2560 disband_implicit_edges (void)
2561 {
2562 basic_block bb;
2563 block_stmt_iterator last;
2564 edge e;
2565 edge_iterator ei;
2566 tree stmt, label;
2567
2568 FOR_EACH_BB (bb)
2569 {
2570 last = bsi_last (bb);
2571 stmt = last_stmt (bb);
2572
2573 if (stmt && TREE_CODE (stmt) == COND_EXPR)
2574 {
2575 /* Remove superfluous gotos from COND_EXPR branches. Moved
2576 from cfg_remove_useless_stmts here since it violates the
2577 invariants for tree--cfg correspondence and thus fits better
2578 here where we do it anyway. */
2579 e = find_edge (bb, bb->next_bb);
2580 if (e)
2581 {
2582 if (e->flags & EDGE_TRUE_VALUE)
2583 COND_EXPR_THEN (stmt) = build_empty_stmt ();
2584 else if (e->flags & EDGE_FALSE_VALUE)
2585 COND_EXPR_ELSE (stmt) = build_empty_stmt ();
2586 else
2587 gcc_unreachable ();
2588 e->flags |= EDGE_FALLTHRU;
2589 }
2590
2591 continue;
2592 }
2593
2594 if (stmt && TREE_CODE (stmt) == RETURN_EXPR)
2595 {
2596 /* Remove the RETURN_EXPR if we may fall though to the exit
2597 instead. */
2598 gcc_assert (single_succ_p (bb));
2599 gcc_assert (single_succ (bb) == EXIT_BLOCK_PTR);
2600
2601 if (bb->next_bb == EXIT_BLOCK_PTR
2602 && !TREE_OPERAND (stmt, 0))
2603 {
2604 bsi_remove (&last);
2605 single_succ_edge (bb)->flags |= EDGE_FALLTHRU;
2606 }
2607 continue;
2608 }
2609
2610 /* There can be no fallthru edge if the last statement is a control
2611 one. */
2612 if (stmt && is_ctrl_stmt (stmt))
2613 continue;
2614
2615 /* Find a fallthru edge and emit the goto if necessary. */
2616 FOR_EACH_EDGE (e, ei, bb->succs)
2617 if (e->flags & EDGE_FALLTHRU)
2618 break;
2619
2620 if (!e || e->dest == bb->next_bb)
2621 continue;
2622
2623 gcc_assert (e->dest != EXIT_BLOCK_PTR);
2624 label = tree_block_label (e->dest);
2625
2626 stmt = build1 (GOTO_EXPR, void_type_node, label);
2627 #ifdef USE_MAPPED_LOCATION
2628 SET_EXPR_LOCATION (stmt, e->goto_locus);
2629 #else
2630 SET_EXPR_LOCUS (stmt, e->goto_locus);
2631 #endif
2632 bsi_insert_after (&last, stmt, BSI_NEW_STMT);
2633 e->flags &= ~EDGE_FALLTHRU;
2634 }
2635 }
2636
2637 /* Remove block annotations and other datastructures. */
2638
2639 void
delete_tree_cfg_annotations(void)2640 delete_tree_cfg_annotations (void)
2641 {
2642 label_to_block_map = NULL;
2643 }
2644
2645
2646 /* Return the first statement in basic block BB. */
2647
2648 tree
first_stmt(basic_block bb)2649 first_stmt (basic_block bb)
2650 {
2651 block_stmt_iterator i = bsi_start (bb);
2652 return !bsi_end_p (i) ? bsi_stmt (i) : NULL_TREE;
2653 }
2654
2655
2656 /* Return the last statement in basic block BB. */
2657
2658 tree
last_stmt(basic_block bb)2659 last_stmt (basic_block bb)
2660 {
2661 block_stmt_iterator b = bsi_last (bb);
2662 return !bsi_end_p (b) ? bsi_stmt (b) : NULL_TREE;
2663 }
2664
2665
2666 /* Return a pointer to the last statement in block BB. */
2667
2668 tree *
last_stmt_ptr(basic_block bb)2669 last_stmt_ptr (basic_block bb)
2670 {
2671 block_stmt_iterator last = bsi_last (bb);
2672 return !bsi_end_p (last) ? bsi_stmt_ptr (last) : NULL;
2673 }
2674
2675
2676 /* Return the last statement of an otherwise empty block. Return NULL
2677 if the block is totally empty, or if it contains more than one
2678 statement. */
2679
2680 tree
last_and_only_stmt(basic_block bb)2681 last_and_only_stmt (basic_block bb)
2682 {
2683 block_stmt_iterator i = bsi_last (bb);
2684 tree last, prev;
2685
2686 if (bsi_end_p (i))
2687 return NULL_TREE;
2688
2689 last = bsi_stmt (i);
2690 bsi_prev (&i);
2691 if (bsi_end_p (i))
2692 return last;
2693
2694 /* Empty statements should no longer appear in the instruction stream.
2695 Everything that might have appeared before should be deleted by
2696 remove_useless_stmts, and the optimizers should just bsi_remove
2697 instead of smashing with build_empty_stmt.
2698
2699 Thus the only thing that should appear here in a block containing
2700 one executable statement is a label. */
2701 prev = bsi_stmt (i);
2702 if (TREE_CODE (prev) == LABEL_EXPR)
2703 return last;
2704 else
2705 return NULL_TREE;
2706 }
2707
2708
2709 /* Mark BB as the basic block holding statement T. */
2710
2711 void
set_bb_for_stmt(tree t,basic_block bb)2712 set_bb_for_stmt (tree t, basic_block bb)
2713 {
2714 if (TREE_CODE (t) == PHI_NODE)
2715 PHI_BB (t) = bb;
2716 else if (TREE_CODE (t) == STATEMENT_LIST)
2717 {
2718 tree_stmt_iterator i;
2719 for (i = tsi_start (t); !tsi_end_p (i); tsi_next (&i))
2720 set_bb_for_stmt (tsi_stmt (i), bb);
2721 }
2722 else
2723 {
2724 stmt_ann_t ann = get_stmt_ann (t);
2725 ann->bb = bb;
2726
2727 /* If the statement is a label, add the label to block-to-labels map
2728 so that we can speed up edge creation for GOTO_EXPRs. */
2729 if (TREE_CODE (t) == LABEL_EXPR)
2730 {
2731 int uid;
2732
2733 t = LABEL_EXPR_LABEL (t);
2734 uid = LABEL_DECL_UID (t);
2735 if (uid == -1)
2736 {
2737 LABEL_DECL_UID (t) = uid = cfun->last_label_uid++;
2738 if (VARRAY_SIZE (label_to_block_map) <= (unsigned) uid)
2739 VARRAY_GROW (label_to_block_map, 3 * uid / 2);
2740 }
2741 else
2742 /* We're moving an existing label. Make sure that we've
2743 removed it from the old block. */
2744 gcc_assert (!bb || !VARRAY_BB (label_to_block_map, uid));
2745 VARRAY_BB (label_to_block_map, uid) = bb;
2746 }
2747 }
2748 }
2749
2750 /* Finds iterator for STMT. */
2751
2752 extern block_stmt_iterator
bsi_for_stmt(tree stmt)2753 bsi_for_stmt (tree stmt)
2754 {
2755 block_stmt_iterator bsi;
2756
2757 for (bsi = bsi_start (bb_for_stmt (stmt)); !bsi_end_p (bsi); bsi_next (&bsi))
2758 if (bsi_stmt (bsi) == stmt)
2759 return bsi;
2760
2761 gcc_unreachable ();
2762 }
2763
2764 /* Mark statement T as modified, and update it. */
2765 static inline void
update_modified_stmts(tree t)2766 update_modified_stmts (tree t)
2767 {
2768 if (TREE_CODE (t) == STATEMENT_LIST)
2769 {
2770 tree_stmt_iterator i;
2771 tree stmt;
2772 for (i = tsi_start (t); !tsi_end_p (i); tsi_next (&i))
2773 {
2774 stmt = tsi_stmt (i);
2775 update_stmt_if_modified (stmt);
2776 }
2777 }
2778 else
2779 update_stmt_if_modified (t);
2780 }
2781
2782 /* Insert statement (or statement list) T before the statement
2783 pointed-to by iterator I. M specifies how to update iterator I
2784 after insertion (see enum bsi_iterator_update). */
2785
2786 void
bsi_insert_before(block_stmt_iterator * i,tree t,enum bsi_iterator_update m)2787 bsi_insert_before (block_stmt_iterator *i, tree t, enum bsi_iterator_update m)
2788 {
2789 set_bb_for_stmt (t, i->bb);
2790 update_modified_stmts (t);
2791 tsi_link_before (&i->tsi, t, m);
2792 }
2793
2794
2795 /* Insert statement (or statement list) T after the statement
2796 pointed-to by iterator I. M specifies how to update iterator I
2797 after insertion (see enum bsi_iterator_update). */
2798
2799 void
bsi_insert_after(block_stmt_iterator * i,tree t,enum bsi_iterator_update m)2800 bsi_insert_after (block_stmt_iterator *i, tree t, enum bsi_iterator_update m)
2801 {
2802 set_bb_for_stmt (t, i->bb);
2803 update_modified_stmts (t);
2804 tsi_link_after (&i->tsi, t, m);
2805 }
2806
2807
2808 /* Remove the statement pointed to by iterator I. The iterator is updated
2809 to the next statement. */
2810
2811 void
bsi_remove(block_stmt_iterator * i)2812 bsi_remove (block_stmt_iterator *i)
2813 {
2814 tree t = bsi_stmt (*i);
2815 set_bb_for_stmt (t, NULL);
2816 delink_stmt_imm_use (t);
2817 tsi_delink (&i->tsi);
2818 mark_stmt_modified (t);
2819 }
2820
2821
2822 /* Move the statement at FROM so it comes right after the statement at TO. */
2823
2824 void
bsi_move_after(block_stmt_iterator * from,block_stmt_iterator * to)2825 bsi_move_after (block_stmt_iterator *from, block_stmt_iterator *to)
2826 {
2827 tree stmt = bsi_stmt (*from);
2828 bsi_remove (from);
2829 bsi_insert_after (to, stmt, BSI_SAME_STMT);
2830 }
2831
2832
2833 /* Move the statement at FROM so it comes right before the statement at TO. */
2834
2835 void
bsi_move_before(block_stmt_iterator * from,block_stmt_iterator * to)2836 bsi_move_before (block_stmt_iterator *from, block_stmt_iterator *to)
2837 {
2838 tree stmt = bsi_stmt (*from);
2839 bsi_remove (from);
2840 bsi_insert_before (to, stmt, BSI_SAME_STMT);
2841 }
2842
2843
2844 /* Move the statement at FROM to the end of basic block BB. */
2845
2846 void
bsi_move_to_bb_end(block_stmt_iterator * from,basic_block bb)2847 bsi_move_to_bb_end (block_stmt_iterator *from, basic_block bb)
2848 {
2849 block_stmt_iterator last = bsi_last (bb);
2850
2851 /* Have to check bsi_end_p because it could be an empty block. */
2852 if (!bsi_end_p (last) && is_ctrl_stmt (bsi_stmt (last)))
2853 bsi_move_before (from, &last);
2854 else
2855 bsi_move_after (from, &last);
2856 }
2857
2858
2859 /* Replace the contents of the statement pointed to by iterator BSI
2860 with STMT. If PRESERVE_EH_INFO is true, the exception handling
2861 information of the original statement is preserved. */
2862
2863 void
bsi_replace(const block_stmt_iterator * bsi,tree stmt,bool preserve_eh_info)2864 bsi_replace (const block_stmt_iterator *bsi, tree stmt, bool preserve_eh_info)
2865 {
2866 int eh_region;
2867 tree orig_stmt = bsi_stmt (*bsi);
2868
2869 SET_EXPR_LOCUS (stmt, EXPR_LOCUS (orig_stmt));
2870 set_bb_for_stmt (stmt, bsi->bb);
2871
2872 /* Preserve EH region information from the original statement, if
2873 requested by the caller. */
2874 if (preserve_eh_info)
2875 {
2876 eh_region = lookup_stmt_eh_region (orig_stmt);
2877 if (eh_region >= 0)
2878 add_stmt_to_eh_region (stmt, eh_region);
2879 }
2880
2881 delink_stmt_imm_use (orig_stmt);
2882 *bsi_stmt_ptr (*bsi) = stmt;
2883 mark_stmt_modified (stmt);
2884 update_modified_stmts (stmt);
2885 }
2886
2887
2888 /* Insert the statement pointed-to by BSI into edge E. Every attempt
2889 is made to place the statement in an existing basic block, but
2890 sometimes that isn't possible. When it isn't possible, the edge is
2891 split and the statement is added to the new block.
2892
2893 In all cases, the returned *BSI points to the correct location. The
2894 return value is true if insertion should be done after the location,
2895 or false if it should be done before the location. If new basic block
2896 has to be created, it is stored in *NEW_BB. */
2897
2898 static bool
tree_find_edge_insert_loc(edge e,block_stmt_iterator * bsi,basic_block * new_bb)2899 tree_find_edge_insert_loc (edge e, block_stmt_iterator *bsi,
2900 basic_block *new_bb)
2901 {
2902 basic_block dest, src;
2903 tree tmp;
2904
2905 dest = e->dest;
2906 restart:
2907
2908 /* If the destination has one predecessor which has no PHI nodes,
2909 insert there. Except for the exit block.
2910
2911 The requirement for no PHI nodes could be relaxed. Basically we
2912 would have to examine the PHIs to prove that none of them used
2913 the value set by the statement we want to insert on E. That
2914 hardly seems worth the effort. */
2915 if (single_pred_p (dest)
2916 && ! phi_nodes (dest)
2917 && dest != EXIT_BLOCK_PTR)
2918 {
2919 *bsi = bsi_start (dest);
2920 if (bsi_end_p (*bsi))
2921 return true;
2922
2923 /* Make sure we insert after any leading labels. */
2924 tmp = bsi_stmt (*bsi);
2925 while (TREE_CODE (tmp) == LABEL_EXPR)
2926 {
2927 bsi_next (bsi);
2928 if (bsi_end_p (*bsi))
2929 break;
2930 tmp = bsi_stmt (*bsi);
2931 }
2932
2933 if (bsi_end_p (*bsi))
2934 {
2935 *bsi = bsi_last (dest);
2936 return true;
2937 }
2938 else
2939 return false;
2940 }
2941
2942 /* If the source has one successor, the edge is not abnormal and
2943 the last statement does not end a basic block, insert there.
2944 Except for the entry block. */
2945 src = e->src;
2946 if ((e->flags & EDGE_ABNORMAL) == 0
2947 && single_succ_p (src)
2948 && src != ENTRY_BLOCK_PTR)
2949 {
2950 *bsi = bsi_last (src);
2951 if (bsi_end_p (*bsi))
2952 return true;
2953
2954 tmp = bsi_stmt (*bsi);
2955 if (!stmt_ends_bb_p (tmp))
2956 return true;
2957
2958 /* Insert code just before returning the value. We may need to decompose
2959 the return in the case it contains non-trivial operand. */
2960 if (TREE_CODE (tmp) == RETURN_EXPR)
2961 {
2962 tree op = TREE_OPERAND (tmp, 0);
2963 if (op && !is_gimple_val (op))
2964 {
2965 gcc_assert (TREE_CODE (op) == MODIFY_EXPR);
2966 bsi_insert_before (bsi, op, BSI_NEW_STMT);
2967 TREE_OPERAND (tmp, 0) = TREE_OPERAND (op, 0);
2968 }
2969 bsi_prev (bsi);
2970 return true;
2971 }
2972 }
2973
2974 /* Otherwise, create a new basic block, and split this edge. */
2975 dest = split_edge (e);
2976 if (new_bb)
2977 *new_bb = dest;
2978 e = single_pred_edge (dest);
2979 goto restart;
2980 }
2981
2982
2983 /* This routine will commit all pending edge insertions, creating any new
2984 basic blocks which are necessary. */
2985
2986 void
bsi_commit_edge_inserts(void)2987 bsi_commit_edge_inserts (void)
2988 {
2989 basic_block bb;
2990 edge e;
2991 edge_iterator ei;
2992
2993 bsi_commit_one_edge_insert (single_succ_edge (ENTRY_BLOCK_PTR), NULL);
2994
2995 FOR_EACH_BB (bb)
2996 FOR_EACH_EDGE (e, ei, bb->succs)
2997 bsi_commit_one_edge_insert (e, NULL);
2998 }
2999
3000
3001 /* Commit insertions pending at edge E. If a new block is created, set NEW_BB
3002 to this block, otherwise set it to NULL. */
3003
3004 void
bsi_commit_one_edge_insert(edge e,basic_block * new_bb)3005 bsi_commit_one_edge_insert (edge e, basic_block *new_bb)
3006 {
3007 if (new_bb)
3008 *new_bb = NULL;
3009 if (PENDING_STMT (e))
3010 {
3011 block_stmt_iterator bsi;
3012 tree stmt = PENDING_STMT (e);
3013
3014 PENDING_STMT (e) = NULL_TREE;
3015
3016 if (tree_find_edge_insert_loc (e, &bsi, new_bb))
3017 bsi_insert_after (&bsi, stmt, BSI_NEW_STMT);
3018 else
3019 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
3020 }
3021 }
3022
3023
3024 /* Add STMT to the pending list of edge E. No actual insertion is
3025 made until a call to bsi_commit_edge_inserts () is made. */
3026
3027 void
bsi_insert_on_edge(edge e,tree stmt)3028 bsi_insert_on_edge (edge e, tree stmt)
3029 {
3030 append_to_statement_list (stmt, &PENDING_STMT (e));
3031 }
3032
3033 /* Similar to bsi_insert_on_edge+bsi_commit_edge_inserts. If a new
3034 block has to be created, it is returned. */
3035
3036 basic_block
bsi_insert_on_edge_immediate(edge e,tree stmt)3037 bsi_insert_on_edge_immediate (edge e, tree stmt)
3038 {
3039 block_stmt_iterator bsi;
3040 basic_block new_bb = NULL;
3041
3042 gcc_assert (!PENDING_STMT (e));
3043
3044 if (tree_find_edge_insert_loc (e, &bsi, &new_bb))
3045 bsi_insert_after (&bsi, stmt, BSI_NEW_STMT);
3046 else
3047 bsi_insert_before (&bsi, stmt, BSI_NEW_STMT);
3048
3049 return new_bb;
3050 }
3051
3052 /*---------------------------------------------------------------------------
3053 Tree specific functions for CFG manipulation
3054 ---------------------------------------------------------------------------*/
3055
3056 /* Reinstall those PHI arguments queued in OLD_EDGE to NEW_EDGE. */
3057
3058 static void
reinstall_phi_args(edge new_edge,edge old_edge)3059 reinstall_phi_args (edge new_edge, edge old_edge)
3060 {
3061 tree var, phi;
3062
3063 if (!PENDING_STMT (old_edge))
3064 return;
3065
3066 for (var = PENDING_STMT (old_edge), phi = phi_nodes (new_edge->dest);
3067 var && phi;
3068 var = TREE_CHAIN (var), phi = PHI_CHAIN (phi))
3069 {
3070 tree result = TREE_PURPOSE (var);
3071 tree arg = TREE_VALUE (var);
3072
3073 gcc_assert (result == PHI_RESULT (phi));
3074
3075 add_phi_arg (phi, arg, new_edge);
3076 }
3077
3078 PENDING_STMT (old_edge) = NULL;
3079 }
3080
3081 /* Returns the basic block after that the new basic block created
3082 by splitting edge EDGE_IN should be placed. Tries to keep the new block
3083 near its "logical" location. This is of most help to humans looking
3084 at debugging dumps. */
3085
3086 static basic_block
split_edge_bb_loc(edge edge_in)3087 split_edge_bb_loc (edge edge_in)
3088 {
3089 basic_block dest = edge_in->dest;
3090
3091 if (dest->prev_bb && find_edge (dest->prev_bb, dest))
3092 return edge_in->src;
3093 else
3094 return dest->prev_bb;
3095 }
3096
3097 /* Split a (typically critical) edge EDGE_IN. Return the new block.
3098 Abort on abnormal edges. */
3099
3100 static basic_block
tree_split_edge(edge edge_in)3101 tree_split_edge (edge edge_in)
3102 {
3103 basic_block new_bb, after_bb, dest, src;
3104 edge new_edge, e;
3105
3106 /* Abnormal edges cannot be split. */
3107 gcc_assert (!(edge_in->flags & EDGE_ABNORMAL));
3108
3109 src = edge_in->src;
3110 dest = edge_in->dest;
3111
3112 after_bb = split_edge_bb_loc (edge_in);
3113
3114 new_bb = create_empty_bb (after_bb);
3115 new_bb->frequency = EDGE_FREQUENCY (edge_in);
3116 new_bb->count = edge_in->count;
3117 new_edge = make_edge (new_bb, dest, EDGE_FALLTHRU);
3118 new_edge->probability = REG_BR_PROB_BASE;
3119 new_edge->count = edge_in->count;
3120
3121 e = redirect_edge_and_branch (edge_in, new_bb);
3122 gcc_assert (e);
3123 reinstall_phi_args (new_edge, e);
3124
3125 return new_bb;
3126 }
3127
3128
3129 /* Return true when BB has label LABEL in it. */
3130
3131 static bool
has_label_p(basic_block bb,tree label)3132 has_label_p (basic_block bb, tree label)
3133 {
3134 block_stmt_iterator bsi;
3135
3136 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3137 {
3138 tree stmt = bsi_stmt (bsi);
3139
3140 if (TREE_CODE (stmt) != LABEL_EXPR)
3141 return false;
3142 if (LABEL_EXPR_LABEL (stmt) == label)
3143 return true;
3144 }
3145 return false;
3146 }
3147
3148
3149 /* Callback for walk_tree, check that all elements with address taken are
3150 properly noticed as such. The DATA is an int* that is 1 if TP was seen
3151 inside a PHI node. */
3152
3153 static tree
verify_expr(tree * tp,int * walk_subtrees,void * data ATTRIBUTE_UNUSED)3154 verify_expr (tree *tp, int *walk_subtrees, void *data ATTRIBUTE_UNUSED)
3155 {
3156 tree t = *tp, x;
3157 bool in_phi = (data != NULL);
3158
3159 if (TYPE_P (t))
3160 *walk_subtrees = 0;
3161
3162 /* Check operand N for being valid GIMPLE and give error MSG if not. */
3163 #define CHECK_OP(N, MSG) \
3164 do { if (!is_gimple_val (TREE_OPERAND (t, N))) \
3165 { error (MSG); return TREE_OPERAND (t, N); }} while (0)
3166
3167 switch (TREE_CODE (t))
3168 {
3169 case SSA_NAME:
3170 if (SSA_NAME_IN_FREE_LIST (t))
3171 {
3172 error ("SSA name in freelist but still referenced");
3173 return *tp;
3174 }
3175 break;
3176
3177 case ASSERT_EXPR:
3178 x = fold (ASSERT_EXPR_COND (t));
3179 if (x == boolean_false_node)
3180 {
3181 error ("ASSERT_EXPR with an always-false condition");
3182 return *tp;
3183 }
3184 break;
3185
3186 case MODIFY_EXPR:
3187 x = TREE_OPERAND (t, 0);
3188 if (TREE_CODE (x) == BIT_FIELD_REF
3189 && is_gimple_reg (TREE_OPERAND (x, 0)))
3190 {
3191 error ("GIMPLE register modified with BIT_FIELD_REF");
3192 return t;
3193 }
3194 break;
3195
3196 case ADDR_EXPR:
3197 {
3198 bool old_invariant;
3199 bool old_constant;
3200 bool old_side_effects;
3201 bool new_invariant;
3202 bool new_constant;
3203 bool new_side_effects;
3204
3205 /* ??? tree-ssa-alias.c may have overlooked dead PHI nodes, missing
3206 dead PHIs that take the address of something. But if the PHI
3207 result is dead, the fact that it takes the address of anything
3208 is irrelevant. Because we can not tell from here if a PHI result
3209 is dead, we just skip this check for PHIs altogether. This means
3210 we may be missing "valid" checks, but what can you do?
3211 This was PR19217. */
3212 if (in_phi)
3213 break;
3214
3215 old_invariant = TREE_INVARIANT (t);
3216 old_constant = TREE_CONSTANT (t);
3217 old_side_effects = TREE_SIDE_EFFECTS (t);
3218
3219 recompute_tree_invarant_for_addr_expr (t);
3220 new_invariant = TREE_INVARIANT (t);
3221 new_side_effects = TREE_SIDE_EFFECTS (t);
3222 new_constant = TREE_CONSTANT (t);
3223
3224 if (old_invariant != new_invariant)
3225 {
3226 error ("invariant not recomputed when ADDR_EXPR changed");
3227 return t;
3228 }
3229
3230 if (old_constant != new_constant)
3231 {
3232 error ("constant not recomputed when ADDR_EXPR changed");
3233 return t;
3234 }
3235 if (old_side_effects != new_side_effects)
3236 {
3237 error ("side effects not recomputed when ADDR_EXPR changed");
3238 return t;
3239 }
3240
3241 /* Skip any references (they will be checked when we recurse down the
3242 tree) and ensure that any variable used as a prefix is marked
3243 addressable. */
3244 for (x = TREE_OPERAND (t, 0);
3245 handled_component_p (x);
3246 x = TREE_OPERAND (x, 0))
3247 ;
3248
3249 if (TREE_CODE (x) != VAR_DECL && TREE_CODE (x) != PARM_DECL)
3250 return NULL;
3251 if (!TREE_ADDRESSABLE (x))
3252 {
3253 error ("address taken, but ADDRESSABLE bit not set");
3254 return x;
3255 }
3256 break;
3257 }
3258
3259 case COND_EXPR:
3260 x = COND_EXPR_COND (t);
3261 if (TREE_CODE (TREE_TYPE (x)) != BOOLEAN_TYPE)
3262 {
3263 error ("non-boolean used in condition");
3264 return x;
3265 }
3266 if (!is_gimple_condexpr (x))
3267 {
3268 error ("invalid conditional operand");
3269 return x;
3270 }
3271 break;
3272
3273 case NOP_EXPR:
3274 case CONVERT_EXPR:
3275 case FIX_TRUNC_EXPR:
3276 case FIX_CEIL_EXPR:
3277 case FIX_FLOOR_EXPR:
3278 case FIX_ROUND_EXPR:
3279 case FLOAT_EXPR:
3280 case NEGATE_EXPR:
3281 case ABS_EXPR:
3282 case BIT_NOT_EXPR:
3283 case NON_LVALUE_EXPR:
3284 case TRUTH_NOT_EXPR:
3285 CHECK_OP (0, "invalid operand to unary operator");
3286 break;
3287
3288 case REALPART_EXPR:
3289 case IMAGPART_EXPR:
3290 case COMPONENT_REF:
3291 case ARRAY_REF:
3292 case ARRAY_RANGE_REF:
3293 case BIT_FIELD_REF:
3294 case VIEW_CONVERT_EXPR:
3295 /* We have a nest of references. Verify that each of the operands
3296 that determine where to reference is either a constant or a variable,
3297 verify that the base is valid, and then show we've already checked
3298 the subtrees. */
3299 while (handled_component_p (t))
3300 {
3301 if (TREE_CODE (t) == COMPONENT_REF && TREE_OPERAND (t, 2))
3302 CHECK_OP (2, "invalid COMPONENT_REF offset operator");
3303 else if (TREE_CODE (t) == ARRAY_REF
3304 || TREE_CODE (t) == ARRAY_RANGE_REF)
3305 {
3306 CHECK_OP (1, "invalid array index");
3307 if (TREE_OPERAND (t, 2))
3308 CHECK_OP (2, "invalid array lower bound");
3309 if (TREE_OPERAND (t, 3))
3310 CHECK_OP (3, "invalid array stride");
3311 }
3312 else if (TREE_CODE (t) == BIT_FIELD_REF)
3313 {
3314 CHECK_OP (1, "invalid operand to BIT_FIELD_REF");
3315 CHECK_OP (2, "invalid operand to BIT_FIELD_REF");
3316 }
3317
3318 t = TREE_OPERAND (t, 0);
3319 }
3320
3321 if (!CONSTANT_CLASS_P (t) && !is_gimple_lvalue (t))
3322 {
3323 error ("invalid reference prefix");
3324 return t;
3325 }
3326 *walk_subtrees = 0;
3327 break;
3328
3329 case LT_EXPR:
3330 case LE_EXPR:
3331 case GT_EXPR:
3332 case GE_EXPR:
3333 case EQ_EXPR:
3334 case NE_EXPR:
3335 case UNORDERED_EXPR:
3336 case ORDERED_EXPR:
3337 case UNLT_EXPR:
3338 case UNLE_EXPR:
3339 case UNGT_EXPR:
3340 case UNGE_EXPR:
3341 case UNEQ_EXPR:
3342 case LTGT_EXPR:
3343 case PLUS_EXPR:
3344 case MINUS_EXPR:
3345 case MULT_EXPR:
3346 case TRUNC_DIV_EXPR:
3347 case CEIL_DIV_EXPR:
3348 case FLOOR_DIV_EXPR:
3349 case ROUND_DIV_EXPR:
3350 case TRUNC_MOD_EXPR:
3351 case CEIL_MOD_EXPR:
3352 case FLOOR_MOD_EXPR:
3353 case ROUND_MOD_EXPR:
3354 case RDIV_EXPR:
3355 case EXACT_DIV_EXPR:
3356 case MIN_EXPR:
3357 case MAX_EXPR:
3358 case LSHIFT_EXPR:
3359 case RSHIFT_EXPR:
3360 case LROTATE_EXPR:
3361 case RROTATE_EXPR:
3362 case BIT_IOR_EXPR:
3363 case BIT_XOR_EXPR:
3364 case BIT_AND_EXPR:
3365 CHECK_OP (0, "invalid operand to binary operator");
3366 CHECK_OP (1, "invalid operand to binary operator");
3367 break;
3368
3369 default:
3370 break;
3371 }
3372 return NULL;
3373
3374 #undef CHECK_OP
3375 }
3376
3377
3378 /* Verify STMT, return true if STMT is not in GIMPLE form.
3379 TODO: Implement type checking. */
3380
3381 static bool
verify_stmt(tree stmt,bool last_in_block)3382 verify_stmt (tree stmt, bool last_in_block)
3383 {
3384 tree addr;
3385
3386 if (!is_gimple_stmt (stmt))
3387 {
3388 error ("is not a valid GIMPLE statement");
3389 goto fail;
3390 }
3391
3392 addr = walk_tree (&stmt, verify_expr, NULL, NULL);
3393 if (addr)
3394 {
3395 debug_generic_stmt (addr);
3396 return true;
3397 }
3398
3399 /* If the statement is marked as part of an EH region, then it is
3400 expected that the statement could throw. Verify that when we
3401 have optimizations that simplify statements such that we prove
3402 that they cannot throw, that we update other data structures
3403 to match. */
3404 if (lookup_stmt_eh_region (stmt) >= 0)
3405 {
3406 if (!tree_could_throw_p (stmt))
3407 {
3408 error ("statement marked for throw, but doesn%'t");
3409 goto fail;
3410 }
3411 if (!last_in_block && tree_can_throw_internal (stmt))
3412 {
3413 error ("statement marked for throw in middle of block");
3414 goto fail;
3415 }
3416 }
3417
3418 return false;
3419
3420 fail:
3421 debug_generic_stmt (stmt);
3422 return true;
3423 }
3424
3425
3426 /* Return true when the T can be shared. */
3427
3428 static bool
tree_node_can_be_shared(tree t)3429 tree_node_can_be_shared (tree t)
3430 {
3431 if (IS_TYPE_OR_DECL_P (t)
3432 /* We check for constants explicitly since they are not considered
3433 gimple invariants if they overflowed. */
3434 || CONSTANT_CLASS_P (t)
3435 || is_gimple_min_invariant (t)
3436 || TREE_CODE (t) == SSA_NAME
3437 || t == error_mark_node)
3438 return true;
3439
3440 if (TREE_CODE (t) == CASE_LABEL_EXPR)
3441 return true;
3442
3443 while (((TREE_CODE (t) == ARRAY_REF || TREE_CODE (t) == ARRAY_RANGE_REF)
3444 /* We check for constants explicitly since they are not considered
3445 gimple invariants if they overflowed. */
3446 && (CONSTANT_CLASS_P (TREE_OPERAND (t, 1))
3447 || is_gimple_min_invariant (TREE_OPERAND (t, 1))))
3448 || (TREE_CODE (t) == COMPONENT_REF
3449 || TREE_CODE (t) == REALPART_EXPR
3450 || TREE_CODE (t) == IMAGPART_EXPR))
3451 t = TREE_OPERAND (t, 0);
3452
3453 if (DECL_P (t))
3454 return true;
3455
3456 return false;
3457 }
3458
3459
3460 /* Called via walk_trees. Verify tree sharing. */
3461
3462 static tree
verify_node_sharing(tree * tp,int * walk_subtrees,void * data)3463 verify_node_sharing (tree * tp, int *walk_subtrees, void *data)
3464 {
3465 htab_t htab = (htab_t) data;
3466 void **slot;
3467
3468 if (tree_node_can_be_shared (*tp))
3469 {
3470 *walk_subtrees = false;
3471 return NULL;
3472 }
3473
3474 slot = htab_find_slot (htab, *tp, INSERT);
3475 if (*slot)
3476 return *slot;
3477 *slot = *tp;
3478
3479 return NULL;
3480 }
3481
3482
3483 /* Verify the GIMPLE statement chain. */
3484
3485 void
verify_stmts(void)3486 verify_stmts (void)
3487 {
3488 basic_block bb;
3489 block_stmt_iterator bsi;
3490 bool err = false;
3491 htab_t htab;
3492 tree addr;
3493
3494 timevar_push (TV_TREE_STMT_VERIFY);
3495 htab = htab_create (37, htab_hash_pointer, htab_eq_pointer, NULL);
3496
3497 FOR_EACH_BB (bb)
3498 {
3499 tree phi;
3500 int i;
3501
3502 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
3503 {
3504 int phi_num_args = PHI_NUM_ARGS (phi);
3505
3506 if (bb_for_stmt (phi) != bb)
3507 {
3508 error ("bb_for_stmt (phi) is set to a wrong basic block");
3509 err |= true;
3510 }
3511
3512 for (i = 0; i < phi_num_args; i++)
3513 {
3514 tree t = PHI_ARG_DEF (phi, i);
3515 tree addr;
3516
3517 /* Addressable variables do have SSA_NAMEs but they
3518 are not considered gimple values. */
3519 if (TREE_CODE (t) != SSA_NAME
3520 && TREE_CODE (t) != FUNCTION_DECL
3521 && !is_gimple_val (t))
3522 {
3523 error ("PHI def is not a GIMPLE value");
3524 debug_generic_stmt (phi);
3525 debug_generic_stmt (t);
3526 err |= true;
3527 }
3528
3529 addr = walk_tree (&t, verify_expr, (void *) 1, NULL);
3530 if (addr)
3531 {
3532 debug_generic_stmt (addr);
3533 err |= true;
3534 }
3535
3536 addr = walk_tree (&t, verify_node_sharing, htab, NULL);
3537 if (addr)
3538 {
3539 error ("incorrect sharing of tree nodes");
3540 debug_generic_stmt (phi);
3541 debug_generic_stmt (addr);
3542 err |= true;
3543 }
3544 }
3545 }
3546
3547 for (bsi = bsi_start (bb); !bsi_end_p (bsi); )
3548 {
3549 tree stmt = bsi_stmt (bsi);
3550
3551 if (bb_for_stmt (stmt) != bb)
3552 {
3553 error ("bb_for_stmt (stmt) is set to a wrong basic block");
3554 err |= true;
3555 }
3556
3557 bsi_next (&bsi);
3558 err |= verify_stmt (stmt, bsi_end_p (bsi));
3559 addr = walk_tree (&stmt, verify_node_sharing, htab, NULL);
3560 if (addr)
3561 {
3562 error ("incorrect sharing of tree nodes");
3563 debug_generic_stmt (stmt);
3564 debug_generic_stmt (addr);
3565 err |= true;
3566 }
3567 }
3568 }
3569
3570 if (err)
3571 internal_error ("verify_stmts failed");
3572
3573 htab_delete (htab);
3574 timevar_pop (TV_TREE_STMT_VERIFY);
3575 }
3576
3577
3578 /* Verifies that the flow information is OK. */
3579
3580 static int
tree_verify_flow_info(void)3581 tree_verify_flow_info (void)
3582 {
3583 int err = 0;
3584 basic_block bb;
3585 block_stmt_iterator bsi;
3586 tree stmt;
3587 edge e;
3588 edge_iterator ei;
3589
3590 if (ENTRY_BLOCK_PTR->stmt_list)
3591 {
3592 error ("ENTRY_BLOCK has a statement list associated with it");
3593 err = 1;
3594 }
3595
3596 if (EXIT_BLOCK_PTR->stmt_list)
3597 {
3598 error ("EXIT_BLOCK has a statement list associated with it");
3599 err = 1;
3600 }
3601
3602 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
3603 if (e->flags & EDGE_FALLTHRU)
3604 {
3605 error ("fallthru to exit from bb %d", e->src->index);
3606 err = 1;
3607 }
3608
3609 FOR_EACH_BB (bb)
3610 {
3611 bool found_ctrl_stmt = false;
3612
3613 stmt = NULL_TREE;
3614
3615 /* Skip labels on the start of basic block. */
3616 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
3617 {
3618 tree prev_stmt = stmt;
3619
3620 stmt = bsi_stmt (bsi);
3621
3622 if (TREE_CODE (stmt) != LABEL_EXPR)
3623 break;
3624
3625 if (prev_stmt && DECL_NONLOCAL (LABEL_EXPR_LABEL (stmt)))
3626 {
3627 error ("nonlocal label %s is not first "
3628 "in a sequence of labels in bb %d",
3629 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt))),
3630 bb->index);
3631 err = 1;
3632 }
3633
3634 if (label_to_block (LABEL_EXPR_LABEL (stmt)) != bb)
3635 {
3636 error ("label %s to block does not match in bb %d",
3637 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt))),
3638 bb->index);
3639 err = 1;
3640 }
3641
3642 if (decl_function_context (LABEL_EXPR_LABEL (stmt))
3643 != current_function_decl)
3644 {
3645 error ("label %s has incorrect context in bb %d",
3646 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt))),
3647 bb->index);
3648 err = 1;
3649 }
3650 }
3651
3652 /* Verify that body of basic block BB is free of control flow. */
3653 for (; !bsi_end_p (bsi); bsi_next (&bsi))
3654 {
3655 tree stmt = bsi_stmt (bsi);
3656
3657 if (found_ctrl_stmt)
3658 {
3659 error ("control flow in the middle of basic block %d",
3660 bb->index);
3661 err = 1;
3662 }
3663
3664 if (stmt_ends_bb_p (stmt))
3665 found_ctrl_stmt = true;
3666
3667 if (TREE_CODE (stmt) == LABEL_EXPR)
3668 {
3669 error ("label %s in the middle of basic block %d",
3670 IDENTIFIER_POINTER (DECL_NAME (LABEL_EXPR_LABEL (stmt))),
3671 bb->index);
3672 err = 1;
3673 }
3674 }
3675 bsi = bsi_last (bb);
3676 if (bsi_end_p (bsi))
3677 continue;
3678
3679 stmt = bsi_stmt (bsi);
3680
3681 err |= verify_eh_edges (stmt);
3682
3683 if (is_ctrl_stmt (stmt))
3684 {
3685 FOR_EACH_EDGE (e, ei, bb->succs)
3686 if (e->flags & EDGE_FALLTHRU)
3687 {
3688 error ("fallthru edge after a control statement in bb %d",
3689 bb->index);
3690 err = 1;
3691 }
3692 }
3693
3694 switch (TREE_CODE (stmt))
3695 {
3696 case COND_EXPR:
3697 {
3698 edge true_edge;
3699 edge false_edge;
3700 if (TREE_CODE (COND_EXPR_THEN (stmt)) != GOTO_EXPR
3701 || TREE_CODE (COND_EXPR_ELSE (stmt)) != GOTO_EXPR)
3702 {
3703 error ("structured COND_EXPR at the end of bb %d", bb->index);
3704 err = 1;
3705 }
3706
3707 extract_true_false_edges_from_block (bb, &true_edge, &false_edge);
3708
3709 if (!true_edge || !false_edge
3710 || !(true_edge->flags & EDGE_TRUE_VALUE)
3711 || !(false_edge->flags & EDGE_FALSE_VALUE)
3712 || (true_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL))
3713 || (false_edge->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL))
3714 || EDGE_COUNT (bb->succs) >= 3)
3715 {
3716 error ("wrong outgoing edge flags at end of bb %d",
3717 bb->index);
3718 err = 1;
3719 }
3720
3721 if (!has_label_p (true_edge->dest,
3722 GOTO_DESTINATION (COND_EXPR_THEN (stmt))))
3723 {
3724 error ("%<then%> label does not match edge at end of bb %d",
3725 bb->index);
3726 err = 1;
3727 }
3728
3729 if (!has_label_p (false_edge->dest,
3730 GOTO_DESTINATION (COND_EXPR_ELSE (stmt))))
3731 {
3732 error ("%<else%> label does not match edge at end of bb %d",
3733 bb->index);
3734 err = 1;
3735 }
3736 }
3737 break;
3738
3739 case GOTO_EXPR:
3740 if (simple_goto_p (stmt))
3741 {
3742 error ("explicit goto at end of bb %d", bb->index);
3743 err = 1;
3744 }
3745 else
3746 {
3747 /* FIXME. We should double check that the labels in the
3748 destination blocks have their address taken. */
3749 FOR_EACH_EDGE (e, ei, bb->succs)
3750 if ((e->flags & (EDGE_FALLTHRU | EDGE_TRUE_VALUE
3751 | EDGE_FALSE_VALUE))
3752 || !(e->flags & EDGE_ABNORMAL))
3753 {
3754 error ("wrong outgoing edge flags at end of bb %d",
3755 bb->index);
3756 err = 1;
3757 }
3758 }
3759 break;
3760
3761 case RETURN_EXPR:
3762 if (!single_succ_p (bb)
3763 || (single_succ_edge (bb)->flags
3764 & (EDGE_FALLTHRU | EDGE_ABNORMAL
3765 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
3766 {
3767 error ("wrong outgoing edge flags at end of bb %d", bb->index);
3768 err = 1;
3769 }
3770 if (single_succ (bb) != EXIT_BLOCK_PTR)
3771 {
3772 error ("return edge does not point to exit in bb %d",
3773 bb->index);
3774 err = 1;
3775 }
3776 break;
3777
3778 case SWITCH_EXPR:
3779 {
3780 tree prev;
3781 edge e;
3782 size_t i, n;
3783 tree vec;
3784
3785 vec = SWITCH_LABELS (stmt);
3786 n = TREE_VEC_LENGTH (vec);
3787
3788 /* Mark all the destination basic blocks. */
3789 for (i = 0; i < n; ++i)
3790 {
3791 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
3792 basic_block label_bb = label_to_block (lab);
3793
3794 gcc_assert (!label_bb->aux || label_bb->aux == (void *)1);
3795 label_bb->aux = (void *)1;
3796 }
3797
3798 /* Verify that the case labels are sorted. */
3799 prev = TREE_VEC_ELT (vec, 0);
3800 for (i = 1; i < n - 1; ++i)
3801 {
3802 tree c = TREE_VEC_ELT (vec, i);
3803 if (! CASE_LOW (c))
3804 {
3805 error ("found default case not at end of case vector");
3806 err = 1;
3807 continue;
3808 }
3809 if (! tree_int_cst_lt (CASE_LOW (prev), CASE_LOW (c)))
3810 {
3811 error ("case labels not sorted:");
3812 print_generic_expr (stderr, prev, 0);
3813 fprintf (stderr," is greater than ");
3814 print_generic_expr (stderr, c, 0);
3815 fprintf (stderr," but comes before it.\n");
3816 err = 1;
3817 }
3818 prev = c;
3819 }
3820 if (CASE_LOW (TREE_VEC_ELT (vec, n - 1)))
3821 {
3822 error ("no default case found at end of case vector");
3823 err = 1;
3824 }
3825
3826 FOR_EACH_EDGE (e, ei, bb->succs)
3827 {
3828 if (!e->dest->aux)
3829 {
3830 error ("extra outgoing edge %d->%d",
3831 bb->index, e->dest->index);
3832 err = 1;
3833 }
3834 e->dest->aux = (void *)2;
3835 if ((e->flags & (EDGE_FALLTHRU | EDGE_ABNORMAL
3836 | EDGE_TRUE_VALUE | EDGE_FALSE_VALUE)))
3837 {
3838 error ("wrong outgoing edge flags at end of bb %d",
3839 bb->index);
3840 err = 1;
3841 }
3842 }
3843
3844 /* Check that we have all of them. */
3845 for (i = 0; i < n; ++i)
3846 {
3847 tree lab = CASE_LABEL (TREE_VEC_ELT (vec, i));
3848 basic_block label_bb = label_to_block (lab);
3849
3850 if (label_bb->aux != (void *)2)
3851 {
3852 error ("missing edge %i->%i",
3853 bb->index, label_bb->index);
3854 err = 1;
3855 }
3856 }
3857
3858 FOR_EACH_EDGE (e, ei, bb->succs)
3859 e->dest->aux = (void *)0;
3860 }
3861
3862 default: ;
3863 }
3864 }
3865
3866 if (dom_computed[CDI_DOMINATORS] >= DOM_NO_FAST_QUERY)
3867 verify_dominators (CDI_DOMINATORS);
3868
3869 return err;
3870 }
3871
3872
3873 /* Updates phi nodes after creating a forwarder block joined
3874 by edge FALLTHRU. */
3875
3876 static void
tree_make_forwarder_block(edge fallthru)3877 tree_make_forwarder_block (edge fallthru)
3878 {
3879 edge e;
3880 edge_iterator ei;
3881 basic_block dummy, bb;
3882 tree phi, new_phi, var;
3883
3884 dummy = fallthru->src;
3885 bb = fallthru->dest;
3886
3887 if (single_pred_p (bb))
3888 return;
3889
3890 /* If we redirected a branch we must create new phi nodes at the
3891 start of BB. */
3892 for (phi = phi_nodes (dummy); phi; phi = PHI_CHAIN (phi))
3893 {
3894 var = PHI_RESULT (phi);
3895 new_phi = create_phi_node (var, bb);
3896 SSA_NAME_DEF_STMT (var) = new_phi;
3897 SET_PHI_RESULT (phi, make_ssa_name (SSA_NAME_VAR (var), phi));
3898 add_phi_arg (new_phi, PHI_RESULT (phi), fallthru);
3899 }
3900
3901 /* Ensure that the PHI node chain is in the same order. */
3902 set_phi_nodes (bb, phi_reverse (phi_nodes (bb)));
3903
3904 /* Add the arguments we have stored on edges. */
3905 FOR_EACH_EDGE (e, ei, bb->preds)
3906 {
3907 if (e == fallthru)
3908 continue;
3909
3910 flush_pending_stmts (e);
3911 }
3912 }
3913
3914
3915 /* Return a non-special label in the head of basic block BLOCK.
3916 Create one if it doesn't exist. */
3917
3918 tree
tree_block_label(basic_block bb)3919 tree_block_label (basic_block bb)
3920 {
3921 block_stmt_iterator i, s = bsi_start (bb);
3922 bool first = true;
3923 tree label, stmt;
3924
3925 for (i = s; !bsi_end_p (i); first = false, bsi_next (&i))
3926 {
3927 stmt = bsi_stmt (i);
3928 if (TREE_CODE (stmt) != LABEL_EXPR)
3929 break;
3930 label = LABEL_EXPR_LABEL (stmt);
3931 if (!DECL_NONLOCAL (label))
3932 {
3933 if (!first)
3934 bsi_move_before (&i, &s);
3935 return label;
3936 }
3937 }
3938
3939 label = create_artificial_label ();
3940 stmt = build1 (LABEL_EXPR, void_type_node, label);
3941 bsi_insert_before (&s, stmt, BSI_NEW_STMT);
3942 return label;
3943 }
3944
3945
3946 /* Attempt to perform edge redirection by replacing a possibly complex
3947 jump instruction by a goto or by removing the jump completely.
3948 This can apply only if all edges now point to the same block. The
3949 parameters and return values are equivalent to
3950 redirect_edge_and_branch. */
3951
3952 static edge
tree_try_redirect_by_replacing_jump(edge e,basic_block target)3953 tree_try_redirect_by_replacing_jump (edge e, basic_block target)
3954 {
3955 basic_block src = e->src;
3956 block_stmt_iterator b;
3957 tree stmt;
3958
3959 /* We can replace or remove a complex jump only when we have exactly
3960 two edges. */
3961 if (EDGE_COUNT (src->succs) != 2
3962 /* Verify that all targets will be TARGET. Specifically, the
3963 edge that is not E must also go to TARGET. */
3964 || EDGE_SUCC (src, EDGE_SUCC (src, 0) == e)->dest != target)
3965 return NULL;
3966
3967 b = bsi_last (src);
3968 if (bsi_end_p (b))
3969 return NULL;
3970 stmt = bsi_stmt (b);
3971
3972 if (TREE_CODE (stmt) == COND_EXPR
3973 || TREE_CODE (stmt) == SWITCH_EXPR)
3974 {
3975 bsi_remove (&b);
3976 e = ssa_redirect_edge (e, target);
3977 e->flags = EDGE_FALLTHRU;
3978 return e;
3979 }
3980
3981 return NULL;
3982 }
3983
3984
3985 /* Redirect E to DEST. Return NULL on failure. Otherwise, return the
3986 edge representing the redirected branch. */
3987
3988 static edge
tree_redirect_edge_and_branch(edge e,basic_block dest)3989 tree_redirect_edge_and_branch (edge e, basic_block dest)
3990 {
3991 basic_block bb = e->src;
3992 block_stmt_iterator bsi;
3993 edge ret;
3994 tree label, stmt;
3995
3996 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
3997 return NULL;
3998
3999 if (e->src != ENTRY_BLOCK_PTR
4000 && (ret = tree_try_redirect_by_replacing_jump (e, dest)))
4001 return ret;
4002
4003 if (e->dest == dest)
4004 return NULL;
4005
4006 label = tree_block_label (dest);
4007
4008 bsi = bsi_last (bb);
4009 stmt = bsi_end_p (bsi) ? NULL : bsi_stmt (bsi);
4010
4011 switch (stmt ? TREE_CODE (stmt) : ERROR_MARK)
4012 {
4013 case COND_EXPR:
4014 stmt = (e->flags & EDGE_TRUE_VALUE
4015 ? COND_EXPR_THEN (stmt)
4016 : COND_EXPR_ELSE (stmt));
4017 GOTO_DESTINATION (stmt) = label;
4018 break;
4019
4020 case GOTO_EXPR:
4021 /* No non-abnormal edges should lead from a non-simple goto, and
4022 simple ones should be represented implicitly. */
4023 gcc_unreachable ();
4024
4025 case SWITCH_EXPR:
4026 {
4027 tree cases = get_cases_for_edge (e, stmt);
4028
4029 /* If we have a list of cases associated with E, then use it
4030 as it's a lot faster than walking the entire case vector. */
4031 if (cases)
4032 {
4033 edge e2 = find_edge (e->src, dest);
4034 tree last, first;
4035
4036 first = cases;
4037 while (cases)
4038 {
4039 last = cases;
4040 CASE_LABEL (cases) = label;
4041 cases = TREE_CHAIN (cases);
4042 }
4043
4044 /* If there was already an edge in the CFG, then we need
4045 to move all the cases associated with E to E2. */
4046 if (e2)
4047 {
4048 tree cases2 = get_cases_for_edge (e2, stmt);
4049
4050 TREE_CHAIN (last) = TREE_CHAIN (cases2);
4051 TREE_CHAIN (cases2) = first;
4052 }
4053 }
4054 else
4055 {
4056 tree vec = SWITCH_LABELS (stmt);
4057 size_t i, n = TREE_VEC_LENGTH (vec);
4058
4059 for (i = 0; i < n; i++)
4060 {
4061 tree elt = TREE_VEC_ELT (vec, i);
4062
4063 if (label_to_block (CASE_LABEL (elt)) == e->dest)
4064 CASE_LABEL (elt) = label;
4065 }
4066 }
4067
4068 break;
4069 }
4070
4071 case RETURN_EXPR:
4072 bsi_remove (&bsi);
4073 e->flags |= EDGE_FALLTHRU;
4074 break;
4075
4076 default:
4077 /* Otherwise it must be a fallthru edge, and we don't need to
4078 do anything besides redirecting it. */
4079 gcc_assert (e->flags & EDGE_FALLTHRU);
4080 break;
4081 }
4082
4083 /* Update/insert PHI nodes as necessary. */
4084
4085 /* Now update the edges in the CFG. */
4086 e = ssa_redirect_edge (e, dest);
4087
4088 return e;
4089 }
4090
4091
4092 /* Simple wrapper, as we can always redirect fallthru edges. */
4093
4094 static basic_block
tree_redirect_edge_and_branch_force(edge e,basic_block dest)4095 tree_redirect_edge_and_branch_force (edge e, basic_block dest)
4096 {
4097 e = tree_redirect_edge_and_branch (e, dest);
4098 gcc_assert (e);
4099
4100 return NULL;
4101 }
4102
4103
4104 /* Splits basic block BB after statement STMT (but at least after the
4105 labels). If STMT is NULL, BB is split just after the labels. */
4106
4107 static basic_block
tree_split_block(basic_block bb,void * stmt)4108 tree_split_block (basic_block bb, void *stmt)
4109 {
4110 block_stmt_iterator bsi, bsi_tgt;
4111 tree act;
4112 basic_block new_bb;
4113 edge e;
4114 edge_iterator ei;
4115
4116 new_bb = create_empty_bb (bb);
4117
4118 /* Redirect the outgoing edges. */
4119 new_bb->succs = bb->succs;
4120 bb->succs = NULL;
4121 FOR_EACH_EDGE (e, ei, new_bb->succs)
4122 e->src = new_bb;
4123
4124 if (stmt && TREE_CODE ((tree) stmt) == LABEL_EXPR)
4125 stmt = NULL;
4126
4127 /* Move everything from BSI to the new basic block. */
4128 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4129 {
4130 act = bsi_stmt (bsi);
4131 if (TREE_CODE (act) == LABEL_EXPR)
4132 continue;
4133
4134 if (!stmt)
4135 break;
4136
4137 if (stmt == act)
4138 {
4139 bsi_next (&bsi);
4140 break;
4141 }
4142 }
4143
4144 bsi_tgt = bsi_start (new_bb);
4145 while (!bsi_end_p (bsi))
4146 {
4147 act = bsi_stmt (bsi);
4148 bsi_remove (&bsi);
4149 bsi_insert_after (&bsi_tgt, act, BSI_NEW_STMT);
4150 }
4151
4152 return new_bb;
4153 }
4154
4155
4156 /* Moves basic block BB after block AFTER. */
4157
4158 static bool
tree_move_block_after(basic_block bb,basic_block after)4159 tree_move_block_after (basic_block bb, basic_block after)
4160 {
4161 if (bb->prev_bb == after)
4162 return true;
4163
4164 unlink_block (bb);
4165 link_block (bb, after);
4166
4167 return true;
4168 }
4169
4170
4171 /* Return true if basic_block can be duplicated. */
4172
4173 static bool
tree_can_duplicate_bb_p(basic_block bb ATTRIBUTE_UNUSED)4174 tree_can_duplicate_bb_p (basic_block bb ATTRIBUTE_UNUSED)
4175 {
4176 return true;
4177 }
4178
4179
4180 /* Create a duplicate of the basic block BB. NOTE: This does not
4181 preserve SSA form. */
4182
4183 static basic_block
tree_duplicate_bb(basic_block bb)4184 tree_duplicate_bb (basic_block bb)
4185 {
4186 basic_block new_bb;
4187 block_stmt_iterator bsi, bsi_tgt;
4188 tree phi;
4189
4190 new_bb = create_empty_bb (EXIT_BLOCK_PTR->prev_bb);
4191
4192 /* Copy the PHI nodes. We ignore PHI node arguments here because
4193 the incoming edges have not been setup yet. */
4194 for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
4195 {
4196 tree copy = create_phi_node (PHI_RESULT (phi), new_bb);
4197 create_new_def_for (PHI_RESULT (copy), copy, PHI_RESULT_PTR (copy));
4198 }
4199
4200 /* Keep the chain of PHI nodes in the same order so that they can be
4201 updated by ssa_redirect_edge. */
4202 set_phi_nodes (new_bb, phi_reverse (phi_nodes (new_bb)));
4203
4204 bsi_tgt = bsi_start (new_bb);
4205 for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi))
4206 {
4207 def_operand_p def_p;
4208 ssa_op_iter op_iter;
4209 tree stmt, copy;
4210 int region;
4211
4212 stmt = bsi_stmt (bsi);
4213 if (TREE_CODE (stmt) == LABEL_EXPR)
4214 continue;
4215
4216 /* Create a new copy of STMT and duplicate STMT's virtual
4217 operands. */
4218 copy = unshare_expr (stmt);
4219 bsi_insert_after (&bsi_tgt, copy, BSI_NEW_STMT);
4220 copy_virtual_operands (copy, stmt);
4221 region = lookup_stmt_eh_region (stmt);
4222 if (region >= 0)
4223 add_stmt_to_eh_region (copy, region);
4224
4225 /* Create new names for all the definitions created by COPY and
4226 add replacement mappings for each new name. */
4227 FOR_EACH_SSA_DEF_OPERAND (def_p, copy, op_iter, SSA_OP_ALL_DEFS)
4228 create_new_def_for (DEF_FROM_PTR (def_p), copy, def_p);
4229 }
4230
4231 return new_bb;
4232 }
4233
4234
4235 /* Basic block BB_COPY was created by code duplication. Add phi node
4236 arguments for edges going out of BB_COPY. The blocks that were
4237 duplicated have BB_DUPLICATED set. */
4238
4239 void
add_phi_args_after_copy_bb(basic_block bb_copy)4240 add_phi_args_after_copy_bb (basic_block bb_copy)
4241 {
4242 basic_block bb, dest;
4243 edge e, e_copy;
4244 edge_iterator ei;
4245 tree phi, phi_copy, phi_next, def;
4246
4247 bb = get_bb_original (bb_copy);
4248
4249 FOR_EACH_EDGE (e_copy, ei, bb_copy->succs)
4250 {
4251 if (!phi_nodes (e_copy->dest))
4252 continue;
4253
4254 if (e_copy->dest->flags & BB_DUPLICATED)
4255 dest = get_bb_original (e_copy->dest);
4256 else
4257 dest = e_copy->dest;
4258
4259 e = find_edge (bb, dest);
4260 if (!e)
4261 {
4262 /* During loop unrolling the target of the latch edge is copied.
4263 In this case we are not looking for edge to dest, but to
4264 duplicated block whose original was dest. */
4265 FOR_EACH_EDGE (e, ei, bb->succs)
4266 if ((e->dest->flags & BB_DUPLICATED)
4267 && get_bb_original (e->dest) == dest)
4268 break;
4269
4270 gcc_assert (e != NULL);
4271 }
4272
4273 for (phi = phi_nodes (e->dest), phi_copy = phi_nodes (e_copy->dest);
4274 phi;
4275 phi = phi_next, phi_copy = PHI_CHAIN (phi_copy))
4276 {
4277 phi_next = PHI_CHAIN (phi);
4278 def = PHI_ARG_DEF_FROM_EDGE (phi, e);
4279 add_phi_arg (phi_copy, def, e_copy);
4280 }
4281 }
4282 }
4283
4284 /* Blocks in REGION_COPY array of length N_REGION were created by
4285 duplication of basic blocks. Add phi node arguments for edges
4286 going from these blocks. */
4287
4288 void
add_phi_args_after_copy(basic_block * region_copy,unsigned n_region)4289 add_phi_args_after_copy (basic_block *region_copy, unsigned n_region)
4290 {
4291 unsigned i;
4292
4293 for (i = 0; i < n_region; i++)
4294 region_copy[i]->flags |= BB_DUPLICATED;
4295
4296 for (i = 0; i < n_region; i++)
4297 add_phi_args_after_copy_bb (region_copy[i]);
4298
4299 for (i = 0; i < n_region; i++)
4300 region_copy[i]->flags &= ~BB_DUPLICATED;
4301 }
4302
4303 /* Duplicates a REGION (set of N_REGION basic blocks) with just a single
4304 important exit edge EXIT. By important we mean that no SSA name defined
4305 inside region is live over the other exit edges of the region. All entry
4306 edges to the region must go to ENTRY->dest. The edge ENTRY is redirected
4307 to the duplicate of the region. SSA form is not updated, but dominance
4308 and loop information is. The new basic blocks are stored to REGION_COPY
4309 in the same order as they had in REGION, provided that REGION_COPY is not
4310 NULL. The function returns false if it is unable to copy the region,
4311 true otherwise. */
4312
4313 bool
tree_duplicate_sese_region(edge entry,edge exit,basic_block * region,unsigned n_region,basic_block * region_copy)4314 tree_duplicate_sese_region (edge entry, edge exit,
4315 basic_block *region, unsigned n_region,
4316 basic_block *region_copy)
4317 {
4318 unsigned i, n_doms;
4319 bool free_region_copy = false, copying_header = false;
4320 struct loop *loop = entry->dest->loop_father;
4321 edge exit_copy;
4322 basic_block *doms;
4323 edge redirected;
4324 int total_freq = 0, entry_freq = 0;
4325 gcov_type total_count = 0, entry_count = 0;
4326
4327 if (!can_copy_bbs_p (region, n_region))
4328 return false;
4329
4330 /* Some sanity checking. Note that we do not check for all possible
4331 missuses of the functions. I.e. if you ask to copy something weird,
4332 it will work, but the state of structures probably will not be
4333 correct. */
4334 for (i = 0; i < n_region; i++)
4335 {
4336 /* We do not handle subloops, i.e. all the blocks must belong to the
4337 same loop. */
4338 if (region[i]->loop_father != loop)
4339 return false;
4340
4341 if (region[i] != entry->dest
4342 && region[i] == loop->header)
4343 return false;
4344 }
4345
4346 loop->copy = loop;
4347
4348 /* In case the function is used for loop header copying (which is the primary
4349 use), ensure that EXIT and its copy will be new latch and entry edges. */
4350 if (loop->header == entry->dest)
4351 {
4352 copying_header = true;
4353 loop->copy = loop->outer;
4354
4355 if (!dominated_by_p (CDI_DOMINATORS, loop->latch, exit->src))
4356 return false;
4357
4358 for (i = 0; i < n_region; i++)
4359 if (region[i] != exit->src
4360 && dominated_by_p (CDI_DOMINATORS, region[i], exit->src))
4361 return false;
4362 }
4363
4364 if (!region_copy)
4365 {
4366 region_copy = xmalloc (sizeof (basic_block) * n_region);
4367 free_region_copy = true;
4368 }
4369
4370 /* gcc_assert (!need_ssa_update_p ()); */
4371
4372 /* Record blocks outside the region that are dominated by something
4373 inside. */
4374 doms = xmalloc (sizeof (basic_block) * n_basic_blocks);
4375 initialize_original_copy_tables ();
4376
4377 n_doms = get_dominated_by_region (CDI_DOMINATORS, region, n_region, doms);
4378
4379 if (entry->dest->count)
4380 {
4381 total_count = entry->dest->count;
4382 entry_count = entry->count;
4383 /* Fix up corner cases, to avoid division by zero or creation of negative
4384 frequencies. */
4385 if (entry_count > total_count)
4386 entry_count = total_count;
4387 }
4388 else
4389 {
4390 total_freq = entry->dest->frequency;
4391 entry_freq = EDGE_FREQUENCY (entry);
4392 /* Fix up corner cases, to avoid division by zero or creation of negative
4393 frequencies. */
4394 if (total_freq == 0)
4395 total_freq = 1;
4396 else if (entry_freq > total_freq)
4397 entry_freq = total_freq;
4398 }
4399
4400 copy_bbs (region, n_region, region_copy, &exit, 1, &exit_copy, loop,
4401 split_edge_bb_loc (entry));
4402 if (total_count)
4403 {
4404 scale_bbs_frequencies_gcov_type (region, n_region,
4405 total_count - entry_count,
4406 total_count);
4407 scale_bbs_frequencies_gcov_type (region_copy, n_region, entry_count,
4408 total_count);
4409 }
4410 else
4411 {
4412 scale_bbs_frequencies_int (region, n_region, total_freq - entry_freq,
4413 total_freq);
4414 scale_bbs_frequencies_int (region_copy, n_region, entry_freq, total_freq);
4415 }
4416
4417 if (copying_header)
4418 {
4419 loop->header = exit->dest;
4420 loop->latch = exit->src;
4421 }
4422
4423 /* Redirect the entry and add the phi node arguments. */
4424 redirected = redirect_edge_and_branch (entry, get_bb_copy (entry->dest));
4425 gcc_assert (redirected != NULL);
4426 flush_pending_stmts (entry);
4427
4428 /* Concerning updating of dominators: We must recount dominators
4429 for entry block and its copy. Anything that is outside of the
4430 region, but was dominated by something inside needs recounting as
4431 well. */
4432 set_immediate_dominator (CDI_DOMINATORS, entry->dest, entry->src);
4433 doms[n_doms++] = get_bb_original (entry->dest);
4434 iterate_fix_dominators (CDI_DOMINATORS, doms, n_doms);
4435 free (doms);
4436
4437 /* Add the other PHI node arguments. */
4438 add_phi_args_after_copy (region_copy, n_region);
4439
4440 if (free_region_copy)
4441 free (region_copy);
4442
4443 free_original_copy_tables ();
4444 return true;
4445 }
4446
4447
4448 /* Dump FUNCTION_DECL FN to file FILE using FLAGS (see TDF_* in tree.h) */
4449
4450 void
dump_function_to_file(tree fn,FILE * file,int flags)4451 dump_function_to_file (tree fn, FILE *file, int flags)
4452 {
4453 tree arg, vars, var;
4454 bool ignore_topmost_bind = false, any_var = false;
4455 basic_block bb;
4456 tree chain;
4457
4458 fprintf (file, "%s (", lang_hooks.decl_printable_name (fn, 2));
4459
4460 arg = DECL_ARGUMENTS (fn);
4461 while (arg)
4462 {
4463 print_generic_expr (file, arg, dump_flags);
4464 if (TREE_CHAIN (arg))
4465 fprintf (file, ", ");
4466 arg = TREE_CHAIN (arg);
4467 }
4468 fprintf (file, ")\n");
4469
4470 if (flags & TDF_DETAILS)
4471 dump_eh_tree (file, DECL_STRUCT_FUNCTION (fn));
4472 if (flags & TDF_RAW)
4473 {
4474 dump_node (fn, TDF_SLIM | flags, file);
4475 return;
4476 }
4477
4478 /* When GIMPLE is lowered, the variables are no longer available in
4479 BIND_EXPRs, so display them separately. */
4480 if (cfun && cfun->decl == fn && cfun->unexpanded_var_list)
4481 {
4482 ignore_topmost_bind = true;
4483
4484 fprintf (file, "{\n");
4485 for (vars = cfun->unexpanded_var_list; vars; vars = TREE_CHAIN (vars))
4486 {
4487 var = TREE_VALUE (vars);
4488
4489 print_generic_decl (file, var, flags);
4490 fprintf (file, "\n");
4491
4492 any_var = true;
4493 }
4494 }
4495
4496 if (cfun && cfun->decl == fn && cfun->cfg && basic_block_info)
4497 {
4498 /* Make a CFG based dump. */
4499 check_bb_profile (ENTRY_BLOCK_PTR, file);
4500 if (!ignore_topmost_bind)
4501 fprintf (file, "{\n");
4502
4503 if (any_var && n_basic_blocks)
4504 fprintf (file, "\n");
4505
4506 FOR_EACH_BB (bb)
4507 dump_generic_bb (file, bb, 2, flags);
4508
4509 fprintf (file, "}\n");
4510 check_bb_profile (EXIT_BLOCK_PTR, file);
4511 }
4512 else
4513 {
4514 int indent;
4515
4516 /* Make a tree based dump. */
4517 chain = DECL_SAVED_TREE (fn);
4518
4519 if (TREE_CODE (chain) == BIND_EXPR)
4520 {
4521 if (ignore_topmost_bind)
4522 {
4523 chain = BIND_EXPR_BODY (chain);
4524 indent = 2;
4525 }
4526 else
4527 indent = 0;
4528 }
4529 else
4530 {
4531 if (!ignore_topmost_bind)
4532 fprintf (file, "{\n");
4533 indent = 2;
4534 }
4535
4536 if (any_var)
4537 fprintf (file, "\n");
4538
4539 print_generic_stmt_indented (file, chain, flags, indent);
4540 if (ignore_topmost_bind)
4541 fprintf (file, "}\n");
4542 }
4543
4544 fprintf (file, "\n\n");
4545 }
4546
4547
4548 /* Pretty print of the loops intermediate representation. */
4549 static void print_loop (FILE *, struct loop *, int);
4550 static void print_pred_bbs (FILE *, basic_block bb);
4551 static void print_succ_bbs (FILE *, basic_block bb);
4552
4553
4554 /* Print on FILE the indexes for the predecessors of basic_block BB. */
4555
4556 static void
print_pred_bbs(FILE * file,basic_block bb)4557 print_pred_bbs (FILE *file, basic_block bb)
4558 {
4559 edge e;
4560 edge_iterator ei;
4561
4562 FOR_EACH_EDGE (e, ei, bb->preds)
4563 fprintf (file, "bb_%d ", e->src->index);
4564 }
4565
4566
4567 /* Print on FILE the indexes for the successors of basic_block BB. */
4568
4569 static void
print_succ_bbs(FILE * file,basic_block bb)4570 print_succ_bbs (FILE *file, basic_block bb)
4571 {
4572 edge e;
4573 edge_iterator ei;
4574
4575 FOR_EACH_EDGE (e, ei, bb->succs)
4576 fprintf (file, "bb_%d ", e->dest->index);
4577 }
4578
4579
4580 /* Pretty print LOOP on FILE, indented INDENT spaces. */
4581
4582 static void
print_loop(FILE * file,struct loop * loop,int indent)4583 print_loop (FILE *file, struct loop *loop, int indent)
4584 {
4585 char *s_indent;
4586 basic_block bb;
4587
4588 if (loop == NULL)
4589 return;
4590
4591 s_indent = (char *) alloca ((size_t) indent + 1);
4592 memset ((void *) s_indent, ' ', (size_t) indent);
4593 s_indent[indent] = '\0';
4594
4595 /* Print the loop's header. */
4596 fprintf (file, "%sloop_%d\n", s_indent, loop->num);
4597
4598 /* Print the loop's body. */
4599 fprintf (file, "%s{\n", s_indent);
4600 FOR_EACH_BB (bb)
4601 if (bb->loop_father == loop)
4602 {
4603 /* Print the basic_block's header. */
4604 fprintf (file, "%s bb_%d (preds = {", s_indent, bb->index);
4605 print_pred_bbs (file, bb);
4606 fprintf (file, "}, succs = {");
4607 print_succ_bbs (file, bb);
4608 fprintf (file, "})\n");
4609
4610 /* Print the basic_block's body. */
4611 fprintf (file, "%s {\n", s_indent);
4612 tree_dump_bb (bb, file, indent + 4);
4613 fprintf (file, "%s }\n", s_indent);
4614 }
4615
4616 print_loop (file, loop->inner, indent + 2);
4617 fprintf (file, "%s}\n", s_indent);
4618 print_loop (file, loop->next, indent);
4619 }
4620
4621
4622 /* Follow a CFG edge from the entry point of the program, and on entry
4623 of a loop, pretty print the loop structure on FILE. */
4624
4625 void
print_loop_ir(FILE * file)4626 print_loop_ir (FILE *file)
4627 {
4628 basic_block bb;
4629
4630 bb = BASIC_BLOCK (0);
4631 if (bb && bb->loop_father)
4632 print_loop (file, bb->loop_father, 0);
4633 }
4634
4635
4636 /* Debugging loops structure at tree level. */
4637
4638 void
debug_loop_ir(void)4639 debug_loop_ir (void)
4640 {
4641 print_loop_ir (stderr);
4642 }
4643
4644
4645 /* Return true if BB ends with a call, possibly followed by some
4646 instructions that must stay with the call. Return false,
4647 otherwise. */
4648
4649 static bool
tree_block_ends_with_call_p(basic_block bb)4650 tree_block_ends_with_call_p (basic_block bb)
4651 {
4652 block_stmt_iterator bsi = bsi_last (bb);
4653 return get_call_expr_in (bsi_stmt (bsi)) != NULL;
4654 }
4655
4656
4657 /* Return true if BB ends with a conditional branch. Return false,
4658 otherwise. */
4659
4660 static bool
tree_block_ends_with_condjump_p(basic_block bb)4661 tree_block_ends_with_condjump_p (basic_block bb)
4662 {
4663 tree stmt = last_stmt (bb);
4664 return (stmt && TREE_CODE (stmt) == COND_EXPR);
4665 }
4666
4667
4668 /* Return true if we need to add fake edge to exit at statement T.
4669 Helper function for tree_flow_call_edges_add. */
4670
4671 static bool
need_fake_edge_p(tree t)4672 need_fake_edge_p (tree t)
4673 {
4674 tree call;
4675
4676 /* NORETURN and LONGJMP calls already have an edge to exit.
4677 CONST and PURE calls do not need one.
4678 We don't currently check for CONST and PURE here, although
4679 it would be a good idea, because those attributes are
4680 figured out from the RTL in mark_constant_function, and
4681 the counter incrementation code from -fprofile-arcs
4682 leads to different results from -fbranch-probabilities. */
4683 call = get_call_expr_in (t);
4684 if (call
4685 && !(call_expr_flags (call) & ECF_NORETURN))
4686 return true;
4687
4688 if (TREE_CODE (t) == ASM_EXPR
4689 && (ASM_VOLATILE_P (t) || ASM_INPUT_P (t)))
4690 return true;
4691
4692 return false;
4693 }
4694
4695
4696 /* Add fake edges to the function exit for any non constant and non
4697 noreturn calls, volatile inline assembly in the bitmap of blocks
4698 specified by BLOCKS or to the whole CFG if BLOCKS is zero. Return
4699 the number of blocks that were split.
4700
4701 The goal is to expose cases in which entering a basic block does
4702 not imply that all subsequent instructions must be executed. */
4703
4704 static int
tree_flow_call_edges_add(sbitmap blocks)4705 tree_flow_call_edges_add (sbitmap blocks)
4706 {
4707 int i;
4708 int blocks_split = 0;
4709 int last_bb = last_basic_block;
4710 bool check_last_block = false;
4711
4712 if (n_basic_blocks == 0)
4713 return 0;
4714
4715 if (! blocks)
4716 check_last_block = true;
4717 else
4718 check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index);
4719
4720 /* In the last basic block, before epilogue generation, there will be
4721 a fallthru edge to EXIT. Special care is required if the last insn
4722 of the last basic block is a call because make_edge folds duplicate
4723 edges, which would result in the fallthru edge also being marked
4724 fake, which would result in the fallthru edge being removed by
4725 remove_fake_edges, which would result in an invalid CFG.
4726
4727 Moreover, we can't elide the outgoing fake edge, since the block
4728 profiler needs to take this into account in order to solve the minimal
4729 spanning tree in the case that the call doesn't return.
4730
4731 Handle this by adding a dummy instruction in a new last basic block. */
4732 if (check_last_block)
4733 {
4734 basic_block bb = EXIT_BLOCK_PTR->prev_bb;
4735 block_stmt_iterator bsi = bsi_last (bb);
4736 tree t = NULL_TREE;
4737 if (!bsi_end_p (bsi))
4738 t = bsi_stmt (bsi);
4739
4740 if (t && need_fake_edge_p (t))
4741 {
4742 edge e;
4743
4744 e = find_edge (bb, EXIT_BLOCK_PTR);
4745 if (e)
4746 {
4747 bsi_insert_on_edge (e, build_empty_stmt ());
4748 bsi_commit_edge_inserts ();
4749 }
4750 }
4751 }
4752
4753 /* Now add fake edges to the function exit for any non constant
4754 calls since there is no way that we can determine if they will
4755 return or not... */
4756 for (i = 0; i < last_bb; i++)
4757 {
4758 basic_block bb = BASIC_BLOCK (i);
4759 block_stmt_iterator bsi;
4760 tree stmt, last_stmt;
4761
4762 if (!bb)
4763 continue;
4764
4765 if (blocks && !TEST_BIT (blocks, i))
4766 continue;
4767
4768 bsi = bsi_last (bb);
4769 if (!bsi_end_p (bsi))
4770 {
4771 last_stmt = bsi_stmt (bsi);
4772 do
4773 {
4774 stmt = bsi_stmt (bsi);
4775 if (need_fake_edge_p (stmt))
4776 {
4777 edge e;
4778 /* The handling above of the final block before the
4779 epilogue should be enough to verify that there is
4780 no edge to the exit block in CFG already.
4781 Calling make_edge in such case would cause us to
4782 mark that edge as fake and remove it later. */
4783 #ifdef ENABLE_CHECKING
4784 if (stmt == last_stmt)
4785 {
4786 e = find_edge (bb, EXIT_BLOCK_PTR);
4787 gcc_assert (e == NULL);
4788 }
4789 #endif
4790
4791 /* Note that the following may create a new basic block
4792 and renumber the existing basic blocks. */
4793 if (stmt != last_stmt)
4794 {
4795 e = split_block (bb, stmt);
4796 if (e)
4797 blocks_split++;
4798 }
4799 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
4800 }
4801 bsi_prev (&bsi);
4802 }
4803 while (!bsi_end_p (bsi));
4804 }
4805 }
4806
4807 if (blocks_split)
4808 verify_flow_info ();
4809
4810 return blocks_split;
4811 }
4812
4813 bool
tree_purge_dead_eh_edges(basic_block bb)4814 tree_purge_dead_eh_edges (basic_block bb)
4815 {
4816 bool changed = false;
4817 edge e;
4818 edge_iterator ei;
4819 tree stmt = last_stmt (bb);
4820
4821 if (stmt && tree_can_throw_internal (stmt))
4822 return false;
4823
4824 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
4825 {
4826 if (e->flags & EDGE_EH)
4827 {
4828 remove_edge (e);
4829 changed = true;
4830 }
4831 else
4832 ei_next (&ei);
4833 }
4834
4835 /* Removal of dead EH edges might change dominators of not
4836 just immediate successors. E.g. when bb1 is changed so that
4837 it no longer can throw and bb1->bb3 and bb1->bb4 are dead
4838 eh edges purged by this function in:
4839 0
4840 / \
4841 v v
4842 1-->2
4843 / \ |
4844 v v |
4845 3-->4 |
4846 \ v
4847 --->5
4848 |
4849 -
4850 idom(bb5) must be recomputed. For now just free the dominance
4851 info. */
4852 if (changed)
4853 free_dominance_info (CDI_DOMINATORS);
4854
4855 return changed;
4856 }
4857
4858 bool
tree_purge_all_dead_eh_edges(bitmap blocks)4859 tree_purge_all_dead_eh_edges (bitmap blocks)
4860 {
4861 bool changed = false;
4862 unsigned i;
4863 bitmap_iterator bi;
4864
4865 EXECUTE_IF_SET_IN_BITMAP (blocks, 0, i, bi)
4866 {
4867 changed |= tree_purge_dead_eh_edges (BASIC_BLOCK (i));
4868 }
4869
4870 return changed;
4871 }
4872
4873 /* This function is called whenever a new edge is created or
4874 redirected. */
4875
4876 static void
tree_execute_on_growing_pred(edge e)4877 tree_execute_on_growing_pred (edge e)
4878 {
4879 basic_block bb = e->dest;
4880
4881 if (phi_nodes (bb))
4882 reserve_phi_args_for_new_edge (bb);
4883 }
4884
4885 /* This function is called immediately before edge E is removed from
4886 the edge vector E->dest->preds. */
4887
4888 static void
tree_execute_on_shrinking_pred(edge e)4889 tree_execute_on_shrinking_pred (edge e)
4890 {
4891 if (phi_nodes (e->dest))
4892 remove_phi_args (e);
4893 }
4894
4895 /*---------------------------------------------------------------------------
4896 Helper functions for Loop versioning
4897 ---------------------------------------------------------------------------*/
4898
4899 /* Adjust phi nodes for 'first' basic block. 'second' basic block is a copy
4900 of 'first'. Both of them are dominated by 'new_head' basic block. When
4901 'new_head' was created by 'second's incoming edge it received phi arguments
4902 on the edge by split_edge(). Later, additional edge 'e' was created to
4903 connect 'new_head' and 'first'. Now this routine adds phi args on this
4904 additional edge 'e' that new_head to second edge received as part of edge
4905 splitting.
4906 */
4907
4908 static void
tree_lv_adjust_loop_header_phi(basic_block first,basic_block second,basic_block new_head,edge e)4909 tree_lv_adjust_loop_header_phi (basic_block first, basic_block second,
4910 basic_block new_head, edge e)
4911 {
4912 tree phi1, phi2;
4913 edge e2 = find_edge (new_head, second);
4914
4915 /* Because NEW_HEAD has been created by splitting SECOND's incoming
4916 edge, we should always have an edge from NEW_HEAD to SECOND. */
4917 gcc_assert (e2 != NULL);
4918
4919 /* Browse all 'second' basic block phi nodes and add phi args to
4920 edge 'e' for 'first' head. PHI args are always in correct order. */
4921
4922 for (phi2 = phi_nodes (second), phi1 = phi_nodes (first);
4923 phi2 && phi1;
4924 phi2 = PHI_CHAIN (phi2), phi1 = PHI_CHAIN (phi1))
4925 {
4926 tree def = PHI_ARG_DEF (phi2, e2->dest_idx);
4927 add_phi_arg (phi1, def, e);
4928 }
4929 }
4930
4931 /* Adds a if else statement to COND_BB with condition COND_EXPR.
4932 SECOND_HEAD is the destination of the THEN and FIRST_HEAD is
4933 the destination of the ELSE part. */
4934 static void
tree_lv_add_condition_to_bb(basic_block first_head,basic_block second_head,basic_block cond_bb,void * cond_e)4935 tree_lv_add_condition_to_bb (basic_block first_head, basic_block second_head,
4936 basic_block cond_bb, void *cond_e)
4937 {
4938 block_stmt_iterator bsi;
4939 tree goto1 = NULL_TREE;
4940 tree goto2 = NULL_TREE;
4941 tree new_cond_expr = NULL_TREE;
4942 tree cond_expr = (tree) cond_e;
4943 edge e0;
4944
4945 /* Build new conditional expr */
4946 goto1 = build1 (GOTO_EXPR, void_type_node, tree_block_label (first_head));
4947 goto2 = build1 (GOTO_EXPR, void_type_node, tree_block_label (second_head));
4948 new_cond_expr = build3 (COND_EXPR, void_type_node, cond_expr, goto1, goto2);
4949
4950 /* Add new cond in cond_bb. */
4951 bsi = bsi_start (cond_bb);
4952 bsi_insert_after (&bsi, new_cond_expr, BSI_NEW_STMT);
4953 /* Adjust edges appropriately to connect new head with first head
4954 as well as second head. */
4955 e0 = single_succ_edge (cond_bb);
4956 e0->flags &= ~EDGE_FALLTHRU;
4957 e0->flags |= EDGE_FALSE_VALUE;
4958 }
4959
4960 struct cfg_hooks tree_cfg_hooks = {
4961 "tree",
4962 tree_verify_flow_info,
4963 tree_dump_bb, /* dump_bb */
4964 create_bb, /* create_basic_block */
4965 tree_redirect_edge_and_branch,/* redirect_edge_and_branch */
4966 tree_redirect_edge_and_branch_force,/* redirect_edge_and_branch_force */
4967 remove_bb, /* delete_basic_block */
4968 tree_split_block, /* split_block */
4969 tree_move_block_after, /* move_block_after */
4970 tree_can_merge_blocks_p, /* can_merge_blocks_p */
4971 tree_merge_blocks, /* merge_blocks */
4972 tree_predict_edge, /* predict_edge */
4973 tree_predicted_by_p, /* predicted_by_p */
4974 tree_can_duplicate_bb_p, /* can_duplicate_block_p */
4975 tree_duplicate_bb, /* duplicate_block */
4976 tree_split_edge, /* split_edge */
4977 tree_make_forwarder_block, /* make_forward_block */
4978 NULL, /* tidy_fallthru_edge */
4979 tree_block_ends_with_call_p, /* block_ends_with_call_p */
4980 tree_block_ends_with_condjump_p, /* block_ends_with_condjump_p */
4981 tree_flow_call_edges_add, /* flow_call_edges_add */
4982 tree_execute_on_growing_pred, /* execute_on_growing_pred */
4983 tree_execute_on_shrinking_pred, /* execute_on_shrinking_pred */
4984 tree_duplicate_loop_to_header_edge, /* duplicate loop for trees */
4985 tree_lv_add_condition_to_bb, /* lv_add_condition_to_bb */
4986 tree_lv_adjust_loop_header_phi, /* lv_adjust_loop_header_phi*/
4987 extract_true_false_edges_from_block, /* extract_cond_bb_edges */
4988 flush_pending_stmts /* flush_pending_stmts */
4989 };
4990
4991
4992 /* Split all critical edges. */
4993
4994 static void
split_critical_edges(void)4995 split_critical_edges (void)
4996 {
4997 basic_block bb;
4998 edge e;
4999 edge_iterator ei;
5000
5001 /* split_edge can redirect edges out of SWITCH_EXPRs, which can get
5002 expensive. So we want to enable recording of edge to CASE_LABEL_EXPR
5003 mappings around the calls to split_edge. */
5004 start_recording_case_labels ();
5005 FOR_ALL_BB (bb)
5006 {
5007 FOR_EACH_EDGE (e, ei, bb->succs)
5008 if (EDGE_CRITICAL_P (e) && !(e->flags & EDGE_ABNORMAL))
5009 {
5010 split_edge (e);
5011 }
5012 }
5013 end_recording_case_labels ();
5014 }
5015
5016 struct tree_opt_pass pass_split_crit_edges =
5017 {
5018 "crited", /* name */
5019 NULL, /* gate */
5020 split_critical_edges, /* execute */
5021 NULL, /* sub */
5022 NULL, /* next */
5023 0, /* static_pass_number */
5024 TV_TREE_SPLIT_EDGES, /* tv_id */
5025 PROP_cfg, /* properties required */
5026 PROP_no_crit_edges, /* properties_provided */
5027 0, /* properties_destroyed */
5028 0, /* todo_flags_start */
5029 TODO_dump_func, /* todo_flags_finish */
5030 0 /* letter */
5031 };
5032
5033
5034 /* Return EXP if it is a valid GIMPLE rvalue, else gimplify it into
5035 a temporary, make sure and register it to be renamed if necessary,
5036 and finally return the temporary. Put the statements to compute
5037 EXP before the current statement in BSI. */
5038
5039 tree
gimplify_val(block_stmt_iterator * bsi,tree type,tree exp)5040 gimplify_val (block_stmt_iterator *bsi, tree type, tree exp)
5041 {
5042 tree t, new_stmt, orig_stmt;
5043
5044 if (is_gimple_val (exp))
5045 return exp;
5046
5047 t = make_rename_temp (type, NULL);
5048 new_stmt = build (MODIFY_EXPR, type, t, exp);
5049
5050 orig_stmt = bsi_stmt (*bsi);
5051 SET_EXPR_LOCUS (new_stmt, EXPR_LOCUS (orig_stmt));
5052 TREE_BLOCK (new_stmt) = TREE_BLOCK (orig_stmt);
5053
5054 bsi_insert_before (bsi, new_stmt, BSI_SAME_STMT);
5055
5056 return t;
5057 }
5058
5059 /* Build a ternary operation and gimplify it. Emit code before BSI.
5060 Return the gimple_val holding the result. */
5061
5062 tree
gimplify_build3(block_stmt_iterator * bsi,enum tree_code code,tree type,tree a,tree b,tree c)5063 gimplify_build3 (block_stmt_iterator *bsi, enum tree_code code,
5064 tree type, tree a, tree b, tree c)
5065 {
5066 tree ret;
5067
5068 ret = fold_build3 (code, type, a, b, c);
5069 STRIP_NOPS (ret);
5070
5071 return gimplify_val (bsi, type, ret);
5072 }
5073
5074 /* Build a binary operation and gimplify it. Emit code before BSI.
5075 Return the gimple_val holding the result. */
5076
5077 tree
gimplify_build2(block_stmt_iterator * bsi,enum tree_code code,tree type,tree a,tree b)5078 gimplify_build2 (block_stmt_iterator *bsi, enum tree_code code,
5079 tree type, tree a, tree b)
5080 {
5081 tree ret;
5082
5083 ret = fold_build2 (code, type, a, b);
5084 STRIP_NOPS (ret);
5085
5086 return gimplify_val (bsi, type, ret);
5087 }
5088
5089 /* Build a unary operation and gimplify it. Emit code before BSI.
5090 Return the gimple_val holding the result. */
5091
5092 tree
gimplify_build1(block_stmt_iterator * bsi,enum tree_code code,tree type,tree a)5093 gimplify_build1 (block_stmt_iterator *bsi, enum tree_code code, tree type,
5094 tree a)
5095 {
5096 tree ret;
5097
5098 ret = fold_build1 (code, type, a);
5099 STRIP_NOPS (ret);
5100
5101 return gimplify_val (bsi, type, ret);
5102 }
5103
5104
5105
5106 /* Emit return warnings. */
5107
5108 static void
execute_warn_function_return(void)5109 execute_warn_function_return (void)
5110 {
5111 #ifdef USE_MAPPED_LOCATION
5112 source_location location;
5113 #else
5114 location_t *locus;
5115 #endif
5116 tree last;
5117 edge e;
5118 edge_iterator ei;
5119
5120 /* If we have a path to EXIT, then we do return. */
5121 if (TREE_THIS_VOLATILE (cfun->decl)
5122 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) > 0)
5123 {
5124 #ifdef USE_MAPPED_LOCATION
5125 location = UNKNOWN_LOCATION;
5126 #else
5127 locus = NULL;
5128 #endif
5129 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
5130 {
5131 last = last_stmt (e->src);
5132 if (TREE_CODE (last) == RETURN_EXPR
5133 #ifdef USE_MAPPED_LOCATION
5134 && (location = EXPR_LOCATION (last)) != UNKNOWN_LOCATION)
5135 #else
5136 && (locus = EXPR_LOCUS (last)) != NULL)
5137 #endif
5138 break;
5139 }
5140 #ifdef USE_MAPPED_LOCATION
5141 if (location == UNKNOWN_LOCATION)
5142 location = cfun->function_end_locus;
5143 warning (0, "%H%<noreturn%> function does return", &location);
5144 #else
5145 if (!locus)
5146 locus = &cfun->function_end_locus;
5147 warning (0, "%H%<noreturn%> function does return", locus);
5148 #endif
5149 }
5150
5151 /* If we see "return;" in some basic block, then we do reach the end
5152 without returning a value. */
5153 else if (warn_return_type
5154 && !TREE_NO_WARNING (cfun->decl)
5155 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) > 0
5156 && !VOID_TYPE_P (TREE_TYPE (TREE_TYPE (cfun->decl))))
5157 {
5158 FOR_EACH_EDGE (e, ei, EXIT_BLOCK_PTR->preds)
5159 {
5160 tree last = last_stmt (e->src);
5161 if (TREE_CODE (last) == RETURN_EXPR
5162 && TREE_OPERAND (last, 0) == NULL
5163 && !TREE_NO_WARNING (last))
5164 {
5165 #ifdef USE_MAPPED_LOCATION
5166 location = EXPR_LOCATION (last);
5167 if (location == UNKNOWN_LOCATION)
5168 location = cfun->function_end_locus;
5169 warning (0, "%Hcontrol reaches end of non-void function", &location);
5170 #else
5171 locus = EXPR_LOCUS (last);
5172 if (!locus)
5173 locus = &cfun->function_end_locus;
5174 warning (0, "%Hcontrol reaches end of non-void function", locus);
5175 #endif
5176 TREE_NO_WARNING (cfun->decl) = 1;
5177 break;
5178 }
5179 }
5180 }
5181 }
5182
5183
5184 /* Given a basic block B which ends with a conditional and has
5185 precisely two successors, determine which of the edges is taken if
5186 the conditional is true and which is taken if the conditional is
5187 false. Set TRUE_EDGE and FALSE_EDGE appropriately. */
5188
5189 void
extract_true_false_edges_from_block(basic_block b,edge * true_edge,edge * false_edge)5190 extract_true_false_edges_from_block (basic_block b,
5191 edge *true_edge,
5192 edge *false_edge)
5193 {
5194 edge e = EDGE_SUCC (b, 0);
5195
5196 if (e->flags & EDGE_TRUE_VALUE)
5197 {
5198 *true_edge = e;
5199 *false_edge = EDGE_SUCC (b, 1);
5200 }
5201 else
5202 {
5203 *false_edge = e;
5204 *true_edge = EDGE_SUCC (b, 1);
5205 }
5206 }
5207
5208 struct tree_opt_pass pass_warn_function_return =
5209 {
5210 NULL, /* name */
5211 NULL, /* gate */
5212 execute_warn_function_return, /* execute */
5213 NULL, /* sub */
5214 NULL, /* next */
5215 0, /* static_pass_number */
5216 0, /* tv_id */
5217 PROP_cfg, /* properties_required */
5218 0, /* properties_provided */
5219 0, /* properties_destroyed */
5220 0, /* todo_flags_start */
5221 0, /* todo_flags_finish */
5222 0 /* letter */
5223 };
5224
5225 /* Emit noreturn warnings. */
5226
5227 static void
execute_warn_function_noreturn(void)5228 execute_warn_function_noreturn (void)
5229 {
5230 if (warn_missing_noreturn
5231 && !TREE_THIS_VOLATILE (cfun->decl)
5232 && EDGE_COUNT (EXIT_BLOCK_PTR->preds) == 0
5233 && !lang_hooks.function.missing_noreturn_ok_p (cfun->decl))
5234 warning (OPT_Wmissing_noreturn, "%Jfunction might be possible candidate "
5235 "for attribute %<noreturn%>",
5236 cfun->decl);
5237 }
5238
5239 struct tree_opt_pass pass_warn_function_noreturn =
5240 {
5241 NULL, /* name */
5242 NULL, /* gate */
5243 execute_warn_function_noreturn, /* execute */
5244 NULL, /* sub */
5245 NULL, /* next */
5246 0, /* static_pass_number */
5247 0, /* tv_id */
5248 PROP_cfg, /* properties_required */
5249 0, /* properties_provided */
5250 0, /* properties_destroyed */
5251 0, /* todo_flags_start */
5252 0, /* todo_flags_finish */
5253 0 /* letter */
5254 };
5255