1/* Control flow graph building code for GNU compiler.
2 Copyright (C) 1987-2017 Free Software Foundation, Inc.
3
4This file is part of GCC.
5
6GCC is free software; you can redistribute it and/or modify it under
7the terms of the GNU General Public License as published by the Free
8Software Foundation; either version 3, or (at your option) any later
9version.
10
11GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12WARRANTY; without even the implied warranty of MERCHANTABILITY or
13FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14for more details.
15
16You should have received a copy of the GNU General Public License
17along with GCC; see the file COPYING3. If not see
18<http://www.gnu.org/licenses/>. */
19
20
21#include "config.h"
22#include "system.h"
23#include "coretypes.h"
24#include "backend.h"
25#include "rtl.h"
26#include "cfghooks.h"
27#include "memmodel.h"
28#include "emit-rtl.h"
29#include "cfgrtl.h"
30#include "cfganal.h"
31#include "cfgbuild.h"
32#include "except.h"
33#include "stmt.h"
34
35static void make_edges (basic_block, basic_block, int);
36static void make_label_edge (sbitmap, basic_block, rtx, int);
37static void find_bb_boundaries (basic_block);
38static void compute_outgoing_frequencies (basic_block);
39
40/* Return true if insn is something that should be contained inside basic
41 block. */
42
43bool
44inside_basic_block_p (const rtx_insn *insn)
45{
46 switch (GET_CODE (insn))
47 {
48 case CODE_LABEL:
49 /* Avoid creating of basic block for jumptables. */
50 return (NEXT_INSN (insn) == 0
51 || ! JUMP_TABLE_DATA_P (NEXT_INSN (insn)));
52
53 case JUMP_INSN:
54 case CALL_INSN:
55 case INSN:
56 case DEBUG_INSN:
57 return true;
58
59 case JUMP_TABLE_DATA:
60 case BARRIER:
61 case NOTE:
62 return false;
63
64 default:
65 gcc_unreachable ();
66 }
67}
68
69/* Return true if INSN may cause control flow transfer, so it should be last in
70 the basic block. */
71
72bool
73control_flow_insn_p (const rtx_insn *insn)
74{
75 switch (GET_CODE (insn))
76 {
77 case NOTE:
78 case CODE_LABEL:
79 case DEBUG_INSN:
80 return false;
81
82 case JUMP_INSN:
83 return true;
84
85 case CALL_INSN:
86 /* Noreturn and sibling call instructions terminate the basic blocks
87 (but only if they happen unconditionally). */
88 if ((SIBLING_CALL_P (insn)
89 || find_reg_note (insn, REG_NORETURN, 0))
90 && GET_CODE (PATTERN (insn)) != COND_EXEC)
91 return true;
92
93 /* Call insn may return to the nonlocal goto handler. */
94 if (can_nonlocal_goto (insn))
95 return true;
96 break;
97
98 case INSN:
99 /* Treat trap instructions like noreturn calls (same provision). */
100 if (GET_CODE (PATTERN (insn)) == TRAP_IF
101 && XEXP (PATTERN (insn), 0) == const1_rtx)
102 return true;
103 if (!cfun->can_throw_non_call_exceptions)
104 return false;
105 break;
106
107 case JUMP_TABLE_DATA:
108 case BARRIER:
109 /* It is nonsense to reach this when looking for the
110 end of basic block, but before dead code is eliminated
111 this may happen. */
112 return false;
113
114 default:
115 gcc_unreachable ();
116 }
117
118 return can_throw_internal (insn);
119}
120
121
122/* Create an edge between two basic blocks. FLAGS are auxiliary information
123 about the edge that is accumulated between calls. */
124
125/* Create an edge from a basic block to a label. */
126
127static void
128make_label_edge (sbitmap edge_cache, basic_block src, rtx label, int flags)
129{
130 gcc_assert (LABEL_P (label));
131
132 /* If the label was never emitted, this insn is junk, but avoid a
133 crash trying to refer to BLOCK_FOR_INSN (label). This can happen
134 as a result of a syntax error and a diagnostic has already been
135 printed. */
136
137 if (INSN_UID (label) == 0)
138 return;
139
140 cached_make_edge (edge_cache, src, BLOCK_FOR_INSN (label), flags);
141}
142
143/* Create the edges generated by INSN in REGION. */
144
145void
146rtl_make_eh_edge (sbitmap edge_cache, basic_block src, rtx insn)
147{
148 eh_landing_pad lp = get_eh_landing_pad_from_rtx (insn);
149
150 if (lp)
151 {
152 rtx_insn *label = lp->landing_pad;
153
154 /* During initial rtl generation, use the post_landing_pad. */
155 if (label == NULL)
156 {
157 gcc_assert (lp->post_landing_pad);
158 label = label_rtx (lp->post_landing_pad);
159 }
160
161 make_label_edge (edge_cache, src, label,
162 EDGE_ABNORMAL | EDGE_EH
163 | (CALL_P (insn) ? EDGE_ABNORMAL_CALL : 0));
164 }
165}
166
167/* States of basic block as seen by find_many_sub_basic_blocks. */
168enum state {
169 /* Basic blocks created via split_block belong to this state.
170 make_edges will examine these basic blocks to see if we need to
171 create edges going out of them. */
172 BLOCK_NEW = 0,
173
174 /* Basic blocks that do not need examining belong to this state.
175 These blocks will be left intact. In particular, make_edges will
176 not create edges going out of these basic blocks. */
177 BLOCK_ORIGINAL,
178
179 /* Basic blocks that may need splitting (due to a label appearing in
180 the middle, etc) belong to this state. After splitting them,
181 make_edges will create edges going out of them as needed. */
182 BLOCK_TO_SPLIT
183};
184
185#define STATE(BB) (enum state) ((size_t) (BB)->aux)
186#define SET_STATE(BB, STATE) ((BB)->aux = (void *) (size_t) (STATE))
187
188/* Used internally by purge_dead_tablejump_edges, ORed into state. */
189#define BLOCK_USED_BY_TABLEJUMP 32
190#define FULL_STATE(BB) ((size_t) (BB)->aux)
191
192/* Identify the edges going out of basic blocks between MIN and MAX,
193 inclusive, that have their states set to BLOCK_NEW or
194 BLOCK_TO_SPLIT.
195
196 UPDATE_P should be nonzero if we are updating CFG and zero if we
197 are building CFG from scratch. */
198
199static void
200make_edges (basic_block min, basic_block max, int update_p)
201{
202 basic_block bb;
203 sbitmap edge_cache = NULL;
204
205 /* Heavy use of computed goto in machine-generated code can lead to
206 nearly fully-connected CFGs. In that case we spend a significant
207 amount of time searching the edge lists for duplicates. */
208 if (!vec_safe_is_empty (forced_labels)
209 || cfun->cfg->max_jumptable_ents > 100)
210 edge_cache = sbitmap_alloc (last_basic_block_for_fn (cfun));
211
212 /* By nature of the way these get numbered, ENTRY_BLOCK_PTR->next_bb block
213 is always the entry. */
214 if (min == ENTRY_BLOCK_PTR_FOR_FN (cfun)->next_bb)
215 make_edge (ENTRY_BLOCK_PTR_FOR_FN (cfun), min, EDGE_FALLTHRU);
216
217 FOR_BB_BETWEEN (bb, min, max->next_bb, next_bb)
218 {
219 rtx_insn *insn;
220 enum rtx_code code;
221 edge e;
222 edge_iterator ei;
223
224 if (STATE (bb) == BLOCK_ORIGINAL)
225 continue;
226
227 /* If we have an edge cache, cache edges going out of BB. */
228 if (edge_cache)
229 {
230 bitmap_clear (edge_cache);
231 if (update_p)
232 {
233 FOR_EACH_EDGE (e, ei, bb->succs)
234 if (e->dest != EXIT_BLOCK_PTR_FOR_FN (cfun))
235 bitmap_set_bit (edge_cache, e->dest->index);
236 }
237 }
238
239 if (LABEL_P (BB_HEAD (bb))
240 && LABEL_ALT_ENTRY_P (BB_HEAD (bb)))
241 cached_make_edge (NULL, ENTRY_BLOCK_PTR_FOR_FN (cfun), bb, 0);
242
243 /* Examine the last instruction of the block, and discover the
244 ways we can leave the block. */
245
246 insn = BB_END (bb);
247 code = GET_CODE (insn);
248
249 /* A branch. */
250 if (code == JUMP_INSN)
251 {
252 rtx tmp;
253 rtx_jump_table_data *table;
254
255 /* Recognize a non-local goto as a branch outside the
256 current function. */
257 if (find_reg_note (insn, REG_NON_LOCAL_GOTO, NULL_RTX))
258 ;
259
260 /* Recognize a tablejump and do the right thing. */
261 else if (tablejump_p (insn, NULL, &table))
262 {
263 rtvec vec = table->get_labels ();
264 int j;
265
266 for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j)
267 make_label_edge (edge_cache, bb,
268 XEXP (RTVEC_ELT (vec, j), 0), 0);
269
270 /* Some targets (eg, ARM) emit a conditional jump that also
271 contains the out-of-range target. Scan for these and
272 add an edge if necessary. */
273 if ((tmp = single_set (insn)) != NULL
274 && SET_DEST (tmp) == pc_rtx
275 && GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE
276 && GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF)
277 make_label_edge (edge_cache, bb,
278 label_ref_label (XEXP (SET_SRC (tmp), 2)), 0);
279 }
280
281 /* If this is a computed jump, then mark it as reaching
282 everything on the forced_labels list. */
283 else if (computed_jump_p (insn))
284 {
285 rtx_insn *insn;
286 unsigned int i;
287 FOR_EACH_VEC_SAFE_ELT (forced_labels, i, insn)
288 make_label_edge (edge_cache, bb, insn, EDGE_ABNORMAL);
289 }
290
291 /* Returns create an exit out. */
292 else if (returnjump_p (insn))
293 cached_make_edge (edge_cache, bb, EXIT_BLOCK_PTR_FOR_FN (cfun), 0);
294
295 /* Recognize asm goto and do the right thing. */
296 else if ((tmp = extract_asm_operands (PATTERN (insn))) != NULL)
297 {
298 int i, n = ASM_OPERANDS_LABEL_LENGTH (tmp);
299 for (i = 0; i < n; ++i)
300 make_label_edge (edge_cache, bb,
301 XEXP (ASM_OPERANDS_LABEL (tmp, i), 0), 0);
302 }
303
304 /* Otherwise, we have a plain conditional or unconditional jump. */
305 else
306 {
307 gcc_assert (JUMP_LABEL (insn));
308 make_label_edge (edge_cache, bb, JUMP_LABEL (insn), 0);
309 }
310 }
311
312 /* If this is a sibling call insn, then this is in effect a combined call
313 and return, and so we need an edge to the exit block. No need to
314 worry about EH edges, since we wouldn't have created the sibling call
315 in the first place. */
316 if (code == CALL_INSN && SIBLING_CALL_P (insn))
317 cached_make_edge (edge_cache, bb, EXIT_BLOCK_PTR_FOR_FN (cfun),
318 EDGE_SIBCALL | EDGE_ABNORMAL);
319
320 /* If this is a CALL_INSN, then mark it as reaching the active EH
321 handler for this CALL_INSN. If we're handling non-call
322 exceptions then any insn can reach any of the active handlers.
323 Also mark the CALL_INSN as reaching any nonlocal goto handler. */
324 else if (code == CALL_INSN || cfun->can_throw_non_call_exceptions)
325 {
326 /* Add any appropriate EH edges. */
327 rtl_make_eh_edge (edge_cache, bb, insn);
328
329 if (code == CALL_INSN)
330 {
331 if (can_nonlocal_goto (insn))
332 {
333 /* ??? This could be made smarter: in some cases it's
334 possible to tell that certain calls will not do a
335 nonlocal goto. For example, if the nested functions
336 that do the nonlocal gotos do not have their addresses
337 taken, then only calls to those functions or to other
338 nested functions that use them could possibly do
339 nonlocal gotos. */
340 for (rtx_insn_list *x = nonlocal_goto_handler_labels;
341 x;
342 x = x->next ())
343 make_label_edge (edge_cache, bb, x->insn (),
344 EDGE_ABNORMAL | EDGE_ABNORMAL_CALL);
345 }
346
347 if (flag_tm)
348 {
349 rtx note;
350 for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
351 if (REG_NOTE_KIND (note) == REG_TM)
352 make_label_edge (edge_cache, bb, XEXP (note, 0),
353 EDGE_ABNORMAL | EDGE_ABNORMAL_CALL);
354 }
355 }
356 }
357
358 /* Find out if we can drop through to the next block. */
359 insn = NEXT_INSN (insn);
360 e = find_edge (bb, EXIT_BLOCK_PTR_FOR_FN (cfun));
361 if (e && e->flags & EDGE_FALLTHRU)
362 insn = NULL;
363
364 while (insn
365 && NOTE_P (insn)
366 && NOTE_KIND (insn) != NOTE_INSN_BASIC_BLOCK)
367 insn = NEXT_INSN (insn);
368
369 if (!insn)
370 cached_make_edge (edge_cache, bb, EXIT_BLOCK_PTR_FOR_FN (cfun),
371 EDGE_FALLTHRU);
372 else if (bb->next_bb != EXIT_BLOCK_PTR_FOR_FN (cfun))
373 {
374 if (insn == BB_HEAD (bb->next_bb))
375 cached_make_edge (edge_cache, bb, bb->next_bb, EDGE_FALLTHRU);
376 }
377 }
378
379 if (edge_cache)
380 sbitmap_free (edge_cache);
381}
382
383static void
384mark_tablejump_edge (rtx label)
385{
386 basic_block bb;
387
388 gcc_assert (LABEL_P (label));
389 /* See comment in make_label_edge. */
390 if (INSN_UID (label) == 0)
391 return;
392 bb = BLOCK_FOR_INSN (label);
393 SET_STATE (bb, FULL_STATE (bb) | BLOCK_USED_BY_TABLEJUMP);
394}
395
396static void
397purge_dead_tablejump_edges (basic_block bb, rtx_jump_table_data *table)
398{
399 rtx_insn *insn = BB_END (bb);
400 rtx tmp;
401 rtvec vec;
402 int j;
403 edge_iterator ei;
404 edge e;
405
406 vec = table->get_labels ();
407
408 for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j)
409 mark_tablejump_edge (XEXP (RTVEC_ELT (vec, j), 0));
410
411 /* Some targets (eg, ARM) emit a conditional jump that also
412 contains the out-of-range target. Scan for these and
413 add an edge if necessary. */
414 if ((tmp = single_set (insn)) != NULL
415 && SET_DEST (tmp) == pc_rtx
416 && GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE
417 && GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF)
418 mark_tablejump_edge (label_ref_label (XEXP (SET_SRC (tmp), 2)));
419
420 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
421 {
422 if (FULL_STATE (e->dest) & BLOCK_USED_BY_TABLEJUMP)
423 SET_STATE (e->dest, FULL_STATE (e->dest)
424 & ~(size_t) BLOCK_USED_BY_TABLEJUMP);
425 else if (!(e->flags & (EDGE_ABNORMAL | EDGE_EH)))
426 {
427 remove_edge (e);
428 continue;
429 }
430 ei_next (&ei);
431 }
432}
433
434/* Scan basic block BB for possible BB boundaries inside the block
435 and create new basic blocks in the progress. */
436
437static void
438find_bb_boundaries (basic_block bb)
439{
440 basic_block orig_bb = bb;
441 rtx_insn *insn = BB_HEAD (bb);
442 rtx_insn *end = BB_END (bb), *x;
443 rtx_jump_table_data *table;
444 rtx_insn *flow_transfer_insn = NULL;
445 rtx_insn *debug_insn = NULL;
446 edge fallthru = NULL;
447 bool skip_purge;
448
449 if (insn == end)
450 return;
451
452 if (DEBUG_INSN_P (insn) || DEBUG_INSN_P (end))
453 {
454 /* Check whether, without debug insns, the insn==end test above
455 would have caused us to return immediately, and behave the
456 same way even with debug insns. If we don't do this, debug
457 insns could cause us to purge dead edges at different times,
458 which could in turn change the cfg and affect codegen
459 decisions in subtle but undesirable ways. */
460 while (insn != end && DEBUG_INSN_P (insn))
461 insn = NEXT_INSN (insn);
462 rtx_insn *e = end;
463 while (insn != e && DEBUG_INSN_P (e))
464 e = PREV_INSN (e);
465 if (insn == e)
466 {
467 /* If there are debug insns after a single insn that is a
468 control flow insn in the block, we'd have left right
469 away, but we should clean up the debug insns after the
470 control flow insn, because they can't remain in the same
471 block. So, do the debug insn cleaning up, but then bail
472 out without purging dead edges as we would if the debug
473 insns hadn't been there. */
474 if (e != end && !DEBUG_INSN_P (e) && control_flow_insn_p (e))
475 {
476 skip_purge = true;
477 flow_transfer_insn = e;
478 goto clean_up_debug_after_control_flow;
479 }
480 return;
481 }
482 }
483
484 if (LABEL_P (insn))
485 insn = NEXT_INSN (insn);
486
487 /* Scan insn chain and try to find new basic block boundaries. */
488 while (1)
489 {
490 enum rtx_code code = GET_CODE (insn);
491
492 if (code == DEBUG_INSN)
493 {
494 if (flow_transfer_insn && !debug_insn)
495 debug_insn = insn;
496 }
497 /* In case we've previously seen an insn that effects a control
498 flow transfer, split the block. */
499 else if ((flow_transfer_insn || code == CODE_LABEL)
500 && inside_basic_block_p (insn))
501 {
502 rtx_insn *prev = PREV_INSN (insn);
503
504 /* If the first non-debug inside_basic_block_p insn after a control
505 flow transfer is not a label, split the block before the debug
506 insn instead of before the non-debug insn, so that the debug
507 insns are not lost. */
508 if (debug_insn && code != CODE_LABEL && code != BARRIER)
509 prev = PREV_INSN (debug_insn);
510 fallthru = split_block (bb, prev);
511 if (flow_transfer_insn)
512 {
513 BB_END (bb) = flow_transfer_insn;
514
515 rtx_insn *next;
516 /* Clean up the bb field for the insns between the blocks. */
517 for (x = NEXT_INSN (flow_transfer_insn);
518 x != BB_HEAD (fallthru->dest);
519 x = next)
520 {
521 next = NEXT_INSN (x);
522 /* Debug insns should not be in between basic blocks,
523 drop them on the floor. */
524 if (DEBUG_INSN_P (x))
525 delete_insn (x);
526 else if (!BARRIER_P (x))
527 set_block_for_insn (x, NULL);
528 }
529 }
530
531 bb = fallthru->dest;
532 remove_edge (fallthru);
533 /* BB is unreachable at this point - we need to determine its profile
534 once edges are built. */
535 bb->count = profile_count::uninitialized ();
536 flow_transfer_insn = NULL;
537 debug_insn = NULL;
538 if (code == CODE_LABEL && LABEL_ALT_ENTRY_P (insn))
539 make_edge (ENTRY_BLOCK_PTR_FOR_FN (cfun), bb, 0);
540 }
541 else if (code == BARRIER)
542 {
543 /* __builtin_unreachable () may cause a barrier to be emitted in
544 the middle of a BB. We need to split it in the same manner as
545 if the barrier were preceded by a control_flow_insn_p insn. */
546 if (!flow_transfer_insn)
547 flow_transfer_insn = prev_nonnote_nondebug_insn_bb (insn);
548 }
549
550 if (control_flow_insn_p (insn))
551 flow_transfer_insn = insn;
552 if (insn == end)
553 break;
554 insn = NEXT_INSN (insn);
555 }
556
557 /* In case expander replaced normal insn by sequence terminating by
558 return and barrier, or possibly other sequence not behaving like
559 ordinary jump, we need to take care and move basic block boundary. */
560 if (flow_transfer_insn && flow_transfer_insn != end)
561 {
562 skip_purge = false;
563
564 clean_up_debug_after_control_flow:
565 BB_END (bb) = flow_transfer_insn;
566
567 /* Clean up the bb field for the insns that do not belong to BB. */
568 rtx_insn *next;
569 for (x = NEXT_INSN (flow_transfer_insn); ; x = next)
570 {
571 next = NEXT_INSN (x);
572 /* Debug insns should not be in between basic blocks,
573 drop them on the floor. */
574 if (DEBUG_INSN_P (x))
575 delete_insn (x);
576 else if (!BARRIER_P (x))
577 set_block_for_insn (x, NULL);
578 if (x == end)
579 break;
580 }
581
582 if (skip_purge)
583 return;
584 }
585
586 /* We've possibly replaced the conditional jump by conditional jump
587 followed by cleanup at fallthru edge, so the outgoing edges may
588 be dead. */
589 purge_dead_edges (bb);
590
591 /* purge_dead_edges doesn't handle tablejump's, but if we have split the
592 basic block, we might need to kill some edges. */
593 if (bb != orig_bb && tablejump_p (BB_END (bb), NULL, &table))
594 purge_dead_tablejump_edges (bb, table);
595}
596
597/* Assume that frequency of basic block B is known. Compute frequencies
598 and probabilities of outgoing edges. */
599
600static void
601compute_outgoing_frequencies (basic_block b)
602{
603 edge e, f;
604 edge_iterator ei;
605
606 if (EDGE_COUNT (b->succs) == 2)
607 {
608 rtx note = find_reg_note (BB_END (b), REG_BR_PROB, NULL);
609 int probability;
610
611 if (note)
612 {
613 probability = XINT (note, 0);
614 e = BRANCH_EDGE (b);
615 e->probability
616 = profile_probability::from_reg_br_prob_note (probability);
617 f = FALLTHRU_EDGE (b);
618 f->probability = e->probability.invert ();
619 return;
620 }
621 else
622 {
623 guess_outgoing_edge_probabilities (b);
624 }
625 }
626 else if (single_succ_p (b))
627 {
628 e = single_succ_edge (b);
629 e->probability = profile_probability::always ();
630 return;
631 }
632 else
633 {
634 /* We rely on BBs with more than two successors to have sane probabilities
635 and do not guess them here. For BBs terminated by switch statements
636 expanded to jump-table jump, we have done the right thing during
637 expansion. For EH edges, we still guess the probabilities here. */
638 bool complex_edge = false;
639 FOR_EACH_EDGE (e, ei, b->succs)
640 if (e->flags & EDGE_COMPLEX)
641 {
642 complex_edge = true;
643 break;
644 }
645 if (complex_edge)
646 guess_outgoing_edge_probabilities (b);
647 }
648}
649
650/* Assume that some pass has inserted labels or control flow
651 instructions within a basic block. Split basic blocks as needed
652 and create edges. */
653
654void
655find_many_sub_basic_blocks (sbitmap blocks)
656{
657 basic_block bb, min, max;
658 bool found = false;
659 auto_vec<unsigned int> n_succs;
660 n_succs.safe_grow_cleared (last_basic_block_for_fn (cfun));
661
662 FOR_EACH_BB_FN (bb, cfun)
663 SET_STATE (bb,
664 bitmap_bit_p (blocks, bb->index) ? BLOCK_TO_SPLIT : BLOCK_ORIGINAL);
665
666 FOR_EACH_BB_FN (bb, cfun)
667 if (STATE (bb) == BLOCK_TO_SPLIT)
668 {
669 int n = last_basic_block_for_fn (cfun);
670 unsigned int ns = EDGE_COUNT (bb->succs);
671
672 find_bb_boundaries (bb);
673 if (n == last_basic_block_for_fn (cfun) && ns == EDGE_COUNT (bb->succs))
674 n_succs[bb->index] = EDGE_COUNT (bb->succs);
675 }
676
677 FOR_EACH_BB_FN (bb, cfun)
678 if (STATE (bb) != BLOCK_ORIGINAL)
679 {
680 found = true;
681 break;
682 }
683
684 if (!found)
685 return;
686
687 min = max = bb;
688 for (; bb != EXIT_BLOCK_PTR_FOR_FN (cfun); bb = bb->next_bb)
689 if (STATE (bb) != BLOCK_ORIGINAL)
690 max = bb;
691
692 /* Now re-scan and wire in all edges. This expect simple (conditional)
693 jumps at the end of each new basic blocks. */
694 make_edges (min, max, 1);
695
696 /* Update branch probabilities. Expect only (un)conditional jumps
697 to be created with only the forward edges. */
698 if (profile_status_for_fn (cfun) != PROFILE_ABSENT)
699 FOR_BB_BETWEEN (bb, min, max->next_bb, next_bb)
700 {
701 edge e;
702 edge_iterator ei;
703
704 if (STATE (bb) == BLOCK_ORIGINAL)
705 continue;
706 if (STATE (bb) == BLOCK_NEW)
707 {
708 bool initialized_src = false, uninitialized_src = false;
709 bb->count = profile_count::zero ();
710 FOR_EACH_EDGE (e, ei, bb->preds)
711 {
712 if (e->count ().initialized_p ())
713 {
714 bb->count += e->count ();
715 initialized_src = true;
716 }
717 else
718 uninitialized_src = true;
719 }
720 /* When some edges are missing with read profile, this is
721 most likely because RTL expansion introduced loop.
722 When profile is guessed we may have BB that is reachable
723 from unlikely path as well as from normal path.
724
725 TODO: We should handle loops created during BB expansion
726 correctly here. For now we assume all those loop to cycle
727 precisely once. */
728 if (!initialized_src
729 || (uninitialized_src
730 && profile_status_for_fn (cfun) < PROFILE_GUESSED))
731 bb->count = profile_count::uninitialized ();
732 }
733 /* If nothing changed, there is no need to create new BBs. */
734 else if (EDGE_COUNT (bb->succs) == n_succs[bb->index])
735 {
736 /* In rare occassions RTL expansion might have mistakely assigned
737 a probabilities different from what is in CFG. This happens
738 when we try to split branch to two but optimize out the
739 second branch during the way. See PR81030. */
740 if (JUMP_P (BB_END (bb)) && any_condjump_p (BB_END (bb))
741 && EDGE_COUNT (bb->succs) >= 2)
742 update_br_prob_note (bb);
743 continue;
744 }
745
746 compute_outgoing_frequencies (bb);
747 }
748
749 FOR_EACH_BB_FN (bb, cfun)
750 SET_STATE (bb, 0);
751}
752