Daily bump.
[official-gcc.git] / gcc / cfgbuild.cc
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1 /* Control flow graph building code for GNU compiler.
2 Copyright (C) 1987-2024 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it under
7 the terms of the GNU General Public License as published by the Free
8 Software Foundation; either version 3, or (at your option) any later
9 version.
11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 for more details.
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING3. If not see
18 <http://www.gnu.org/licenses/>. */
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"
35 static void make_edges (basic_block, basic_block, int);
36 static void make_label_edge (sbitmap, basic_block, rtx, int);
37 static void find_bb_boundaries (basic_block);
38 static void compute_outgoing_frequencies (basic_block);
40 /* Return true if insn is something that should be contained inside basic
41 block. */
43 bool
44 inside_basic_block_p (const rtx_insn *insn)
46 switch (GET_CODE (insn))
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)));
53 case JUMP_INSN:
54 case CALL_INSN:
55 case INSN:
56 case DEBUG_INSN:
57 return true;
59 case JUMP_TABLE_DATA:
60 case BARRIER:
61 case NOTE:
62 return false;
64 default:
65 gcc_unreachable ();
69 /* Return true if INSN may cause control flow transfer, so it should be last in
70 the basic block. */
72 bool
73 control_flow_insn_p (const rtx_insn *insn)
75 switch (GET_CODE (insn))
77 case NOTE:
78 case CODE_LABEL:
79 case DEBUG_INSN:
80 return false;
82 case JUMP_INSN:
83 return true;
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;
93 /* Call insn may return to the nonlocal goto handler. */
94 if (can_nonlocal_goto (insn))
95 return true;
96 break;
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;
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;
114 default:
115 gcc_unreachable ();
118 return can_throw_internal (insn);
122 /* Create an edge between two basic blocks. FLAGS are auxiliary information
123 about the edge that is accumulated between calls. */
125 /* Create an edge from a basic block to a label. */
127 static void
128 make_label_edge (sbitmap edge_cache, basic_block src, rtx label, int flags)
130 gcc_assert (LABEL_P (label));
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. */
137 if (INSN_UID (label) == 0)
138 return;
140 cached_make_edge (edge_cache, src, BLOCK_FOR_INSN (label), flags);
143 /* Create the edges generated by INSN in REGION. */
145 void
146 rtl_make_eh_edge (sbitmap edge_cache, basic_block src, rtx insn)
148 eh_landing_pad lp = get_eh_landing_pad_from_rtx (insn);
150 if (lp)
152 rtx_insn *label = lp->landing_pad;
154 /* During initial rtl generation, use the post_landing_pad. */
155 if (label == NULL)
157 gcc_assert (lp->post_landing_pad);
158 label = label_rtx (lp->post_landing_pad);
161 make_label_edge (edge_cache, src, label,
162 EDGE_ABNORMAL | EDGE_EH
163 | (CALL_P (insn) ? EDGE_ABNORMAL_CALL : 0));
167 /* States of basic block as seen by find_many_sub_basic_blocks. */
168 enum 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,
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,
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
185 #define STATE(BB) (enum state) ((size_t) (BB)->aux)
186 #define SET_STATE(BB, STATE) ((BB)->aux = (void *) (size_t) (STATE))
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)
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.
196 UPDATE_P should be nonzero if we are updating CFG and zero if we
197 are building CFG from scratch. */
199 static void
200 make_edges (basic_block min, basic_block max, int update_p)
202 basic_block bb;
203 sbitmap edge_cache = NULL;
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));
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);
217 FOR_BB_BETWEEN (bb, min, max->next_bb, next_bb)
219 rtx_insn *insn;
220 enum rtx_code code;
221 edge e;
222 edge_iterator ei;
224 if (STATE (bb) == BLOCK_ORIGINAL)
225 continue;
227 /* If we have an edge cache, cache edges going out of BB. */
228 if (edge_cache)
230 bitmap_clear (edge_cache);
231 if (update_p)
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);
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);
243 /* Examine the last instruction of the block, and discover the
244 ways we can leave the block. */
246 insn = BB_END (bb);
247 code = GET_CODE (insn);
249 /* A branch. */
250 if (code == JUMP_INSN)
252 rtx tmp;
253 rtx_jump_table_data *table;
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))
260 /* Recognize a tablejump and do the right thing. */
261 else if (tablejump_p (insn, NULL, &table))
263 rtvec vec = table->get_labels ();
264 int j;
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);
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);
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))
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);
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);
295 /* Recognize asm goto and do the right thing. */
296 else if ((tmp = extract_asm_operands (PATTERN (insn))) != NULL)
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);
304 /* Otherwise, we have a plain conditional or unconditional jump. */
305 else
307 gcc_assert (JUMP_LABEL (insn));
308 make_label_edge (edge_cache, bb, JUMP_LABEL (insn), 0);
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);
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)
326 /* Add any appropriate EH edges. */
327 rtl_make_eh_edge (edge_cache, bb, insn);
329 if (code == CALL_INSN)
331 if (can_nonlocal_goto (insn))
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;
342 x = x->next ())
343 make_label_edge (edge_cache, bb, x->insn (),
344 EDGE_ABNORMAL | EDGE_ABNORMAL_CALL);
347 if (flag_tm)
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);
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;
364 while (insn
365 && NOTE_P (insn)
366 && NOTE_KIND (insn) != NOTE_INSN_BASIC_BLOCK)
367 insn = NEXT_INSN (insn);
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))
374 if (insn == BB_HEAD (bb->next_bb))
375 cached_make_edge (edge_cache, bb, bb->next_bb, EDGE_FALLTHRU);
379 if (edge_cache)
380 sbitmap_free (edge_cache);
383 static void
384 mark_tablejump_edge (rtx label)
386 basic_block bb;
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);
396 static void
397 purge_dead_tablejump_edges (basic_block bb, rtx_jump_table_data *table)
399 rtx_insn *insn = BB_END (bb);
400 rtx tmp;
401 rtvec vec;
402 int j;
403 edge_iterator ei;
404 edge e;
406 vec = table->get_labels ();
408 for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j)
409 mark_tablejump_edge (XEXP (RTVEC_ELT (vec, j), 0));
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)));
420 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
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)))
427 remove_edge (e);
428 continue;
430 ei_next (&ei);
434 /* Scan basic block BB for possible BB boundaries inside the block
435 and create new basic blocks in the progress. */
437 static void
438 find_bb_boundaries (basic_block bb)
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 bool seen_note_after_debug = false;
450 if (insn == end)
451 return;
453 if (DEBUG_INSN_P (insn) || DEBUG_INSN_P (end))
455 /* Check whether, without debug insns, the insn==end test above
456 would have caused us to return immediately, and behave the
457 same way even with debug insns. If we don't do this, debug
458 insns could cause us to purge dead edges at different times,
459 which could in turn change the cfg and affect codegen
460 decisions in subtle but undesirable ways. */
461 while (insn != end && DEBUG_INSN_P (insn))
462 insn = NEXT_INSN (insn);
463 rtx_insn *e = end;
464 while (insn != e && DEBUG_INSN_P (e))
465 e = PREV_INSN (e);
466 if (insn == e)
468 /* If there are debug insns after a single insn that is a
469 control flow insn in the block, we'd have left right
470 away, but we should clean up the debug insns after the
471 control flow insn, because they can't remain in the same
472 block. So, do the debug insn cleaning up, but then bail
473 out without purging dead edges as we would if the debug
474 insns hadn't been there. */
475 if (e != end && !DEBUG_INSN_P (e) && control_flow_insn_p (e))
477 skip_purge = true;
478 flow_transfer_insn = e;
479 goto clean_up_debug_after_control_flow;
481 return;
485 if (LABEL_P (insn))
486 insn = NEXT_INSN (insn);
488 /* Scan insn chain and try to find new basic block boundaries. */
489 while (1)
491 enum rtx_code code = GET_CODE (insn);
493 if (code == DEBUG_INSN)
495 if (flow_transfer_insn && !debug_insn)
497 debug_insn = insn;
498 seen_note_after_debug = false;
501 /* In case we've previously seen an insn that effects a control
502 flow transfer, split the block. */
503 else if ((flow_transfer_insn || code == CODE_LABEL)
504 && inside_basic_block_p (insn))
506 rtx_insn *prev = PREV_INSN (insn);
508 /* If the first non-debug inside_basic_block_p insn after a control
509 flow transfer is not a label, split the block before the debug
510 insn instead of before the non-debug insn, so that the debug
511 insns are not lost. */
512 if (debug_insn && code != CODE_LABEL && code != BARRIER)
514 prev = PREV_INSN (debug_insn);
515 if (seen_note_after_debug)
517 /* Though, if there are NOTEs intermixed with DEBUG_INSNs,
518 move the NOTEs before the DEBUG_INSNs and split after
519 the last NOTE. */
520 rtx_insn *first = NULL, *last = NULL;
521 for (x = debug_insn; x != insn; x = NEXT_INSN (x))
523 if (NOTE_P (x))
525 if (first == NULL)
526 first = x;
527 last = x;
529 else
531 gcc_assert (DEBUG_INSN_P (x));
532 if (first)
534 reorder_insns_nobb (first, last, prev);
535 prev = last;
536 first = last = NULL;
540 if (first)
542 reorder_insns_nobb (first, last, prev);
543 prev = last;
547 fallthru = split_block (bb, prev);
548 if (flow_transfer_insn)
550 BB_END (bb) = flow_transfer_insn;
552 rtx_insn *next;
553 /* Clean up the bb field for the insns between the blocks. */
554 for (x = NEXT_INSN (flow_transfer_insn);
555 x != BB_HEAD (fallthru->dest);
556 x = next)
558 next = NEXT_INSN (x);
559 /* Debug insns should not be in between basic blocks,
560 drop them on the floor. */
561 if (DEBUG_INSN_P (x))
562 delete_insn (x);
563 else if (!BARRIER_P (x))
564 set_block_for_insn (x, NULL);
568 bb = fallthru->dest;
569 remove_edge (fallthru);
570 /* BB is unreachable at this point - we need to determine its profile
571 once edges are built. */
572 bb->count = profile_count::uninitialized ();
573 flow_transfer_insn = NULL;
574 debug_insn = NULL;
575 if (code == CODE_LABEL && LABEL_ALT_ENTRY_P (insn))
576 make_edge (ENTRY_BLOCK_PTR_FOR_FN (cfun), bb, 0);
578 else if (code == BARRIER)
580 /* __builtin_unreachable () may cause a barrier to be emitted in
581 the middle of a BB. We need to split it in the same manner as
582 if the barrier were preceded by a control_flow_insn_p insn. */
583 if (!flow_transfer_insn)
584 flow_transfer_insn = prev_nonnote_nondebug_insn_bb (insn);
585 debug_insn = NULL;
587 else if (debug_insn)
589 if (code == NOTE)
590 seen_note_after_debug = true;
591 else
592 /* Jump tables. */
593 debug_insn = NULL;
596 if (control_flow_insn_p (insn))
597 flow_transfer_insn = insn;
598 if (insn == end)
599 break;
600 insn = NEXT_INSN (insn);
603 /* In case expander replaced normal insn by sequence terminating by
604 return and barrier, or possibly other sequence not behaving like
605 ordinary jump, we need to take care and move basic block boundary. */
606 if (flow_transfer_insn && flow_transfer_insn != end)
608 skip_purge = false;
610 clean_up_debug_after_control_flow:
611 BB_END (bb) = flow_transfer_insn;
613 /* Clean up the bb field for the insns that do not belong to BB. */
614 rtx_insn *next;
615 for (x = NEXT_INSN (flow_transfer_insn); ; x = next)
617 next = NEXT_INSN (x);
618 /* Debug insns should not be in between basic blocks,
619 drop them on the floor. */
620 if (DEBUG_INSN_P (x))
621 delete_insn (x);
622 else if (!BARRIER_P (x))
623 set_block_for_insn (x, NULL);
624 if (x == end)
625 break;
628 if (skip_purge)
629 return;
632 /* We've possibly replaced the conditional jump by conditional jump
633 followed by cleanup at fallthru edge, so the outgoing edges may
634 be dead. */
635 purge_dead_edges (bb);
637 /* purge_dead_edges doesn't handle tablejump's, but if we have split the
638 basic block, we might need to kill some edges. */
639 if (bb != orig_bb && tablejump_p (BB_END (bb), NULL, &table))
640 purge_dead_tablejump_edges (bb, table);
643 /* Assume that frequency of basic block B is known. Compute frequencies
644 and probabilities of outgoing edges. */
646 static void
647 compute_outgoing_frequencies (basic_block b)
649 edge e, f;
650 edge_iterator ei;
652 if (EDGE_COUNT (b->succs) == 2)
654 rtx note = find_reg_note (BB_END (b), REG_BR_PROB, NULL);
655 int probability;
657 if (note)
659 probability = XINT (note, 0);
660 e = BRANCH_EDGE (b);
661 e->probability
662 = profile_probability::from_reg_br_prob_note (probability);
663 f = FALLTHRU_EDGE (b);
664 f->probability = e->probability.invert ();
665 return;
667 else
669 guess_outgoing_edge_probabilities (b);
672 else if (single_succ_p (b))
674 e = single_succ_edge (b);
675 e->probability = profile_probability::always ();
676 return;
678 else
680 /* We rely on BBs with more than two successors to have sane probabilities
681 and do not guess them here. For BBs terminated by switch statements
682 expanded to jump-table jump, we have done the right thing during
683 expansion. For EH edges, we still guess the probabilities here. */
684 bool complex_edge = false;
685 FOR_EACH_EDGE (e, ei, b->succs)
686 if (e->flags & EDGE_COMPLEX)
688 complex_edge = true;
689 break;
691 if (complex_edge)
692 guess_outgoing_edge_probabilities (b);
696 /* Update the profile information for BB, which was created by splitting
697 an RTL block that had a non-final jump. */
699 static void
700 update_profile_for_new_sub_basic_block (basic_block bb)
702 edge e;
703 edge_iterator ei;
705 bool initialized_src = false, uninitialized_src = false;
706 bb->count = profile_count::zero ();
707 FOR_EACH_EDGE (e, ei, bb->preds)
709 if (e->count ().initialized_p ())
711 bb->count += e->count ();
712 initialized_src = true;
714 else
715 uninitialized_src = true;
717 /* When some edges are missing with read profile, this is
718 most likely because RTL expansion introduced loop.
719 When profile is guessed we may have BB that is reachable
720 from unlikely path as well as from normal path.
722 TODO: We should handle loops created during BB expansion
723 correctly here. For now we assume all those loop to cycle
724 precisely once. */
725 if (!initialized_src
726 || (uninitialized_src
727 && profile_status_for_fn (cfun) < PROFILE_GUESSED))
728 bb->count = profile_count::uninitialized ();
730 compute_outgoing_frequencies (bb);
733 /* Assume that some pass has inserted labels or control flow
734 instructions within a basic block. Split basic blocks as needed
735 and create edges. */
737 void
738 find_many_sub_basic_blocks (sbitmap blocks)
740 basic_block bb, min, max;
741 bool found = false;
742 auto_vec<unsigned int> n_succs;
743 n_succs.safe_grow_cleared (last_basic_block_for_fn (cfun), true);
745 FOR_EACH_BB_FN (bb, cfun)
746 SET_STATE (bb,
747 bitmap_bit_p (blocks, bb->index) ? BLOCK_TO_SPLIT : BLOCK_ORIGINAL);
749 FOR_EACH_BB_FN (bb, cfun)
750 if (STATE (bb) == BLOCK_TO_SPLIT)
752 int n = last_basic_block_for_fn (cfun);
753 unsigned int ns = EDGE_COUNT (bb->succs);
755 find_bb_boundaries (bb);
756 if (n == last_basic_block_for_fn (cfun) && ns == EDGE_COUNT (bb->succs))
757 n_succs[bb->index] = EDGE_COUNT (bb->succs);
760 FOR_EACH_BB_FN (bb, cfun)
761 if (STATE (bb) != BLOCK_ORIGINAL)
763 found = true;
764 break;
767 if (!found)
768 return;
770 min = max = bb;
771 for (; bb != EXIT_BLOCK_PTR_FOR_FN (cfun); bb = bb->next_bb)
772 if (STATE (bb) != BLOCK_ORIGINAL)
773 max = bb;
775 /* Now re-scan and wire in all edges. This expect simple (conditional)
776 jumps at the end of each new basic blocks. */
777 make_edges (min, max, 1);
779 /* Update branch probabilities. Expect only (un)conditional jumps
780 to be created with only the forward edges. */
781 if (profile_status_for_fn (cfun) != PROFILE_ABSENT)
782 FOR_BB_BETWEEN (bb, min, max->next_bb, next_bb)
784 if (STATE (bb) == BLOCK_ORIGINAL)
785 continue;
786 if (STATE (bb) == BLOCK_NEW)
788 update_profile_for_new_sub_basic_block (bb);
789 continue;
791 /* If nothing changed, there is no need to create new BBs. */
792 if (EDGE_COUNT (bb->succs) == n_succs[bb->index])
794 /* In rare occassions RTL expansion might have mistakely assigned
795 a probabilities different from what is in CFG. This happens
796 when we try to split branch to two but optimize out the
797 second branch during the way. See PR81030. */
798 if (JUMP_P (BB_END (bb)) && any_condjump_p (BB_END (bb))
799 && EDGE_COUNT (bb->succs) >= 2)
800 update_br_prob_note (bb);
801 continue;
803 compute_outgoing_frequencies (bb);
806 FOR_EACH_BB_FN (bb, cfun)
807 SET_STATE (bb, 0);
810 /* Like find_many_sub_basic_blocks, but look only within BB. */
812 void
813 find_sub_basic_blocks (basic_block bb)
815 basic_block end_bb = bb->next_bb;
816 find_bb_boundaries (bb);
817 if (bb->next_bb == end_bb)
818 return;
820 /* Re-scan and wire in all edges. This expects simple (conditional)
821 jumps at the end of each new basic blocks. */
822 make_edges (bb, end_bb->prev_bb, 1);
824 /* Update branch probabilities. Expect only (un)conditional jumps
825 to be created with only the forward edges. */
826 if (profile_status_for_fn (cfun) != PROFILE_ABSENT)
828 compute_outgoing_frequencies (bb);
829 for (bb = bb->next_bb; bb != end_bb; bb = bb->next_bb)
830 update_profile_for_new_sub_basic_block (bb);