Line data Source code
1 : /* Control flow optimization code for GNU compiler.
2 : Copyright (C) 1987-2026 Free Software Foundation, Inc.
3 :
4 : This file is part of GCC.
5 :
6 : GCC is free software; you can redistribute it and/or modify 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.
10 :
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.
15 :
16 : You should have received a copy of the GNU General Public License
17 : along with GCC; see the file COPYING3. If not see
18 : <http://www.gnu.org/licenses/>. */
19 :
20 : /* This file contains optimizer of the control flow. The main entry point is
21 : cleanup_cfg. Following optimizations are performed:
22 :
23 : - Unreachable blocks removal
24 : - Edge forwarding (edge to the forwarder block is forwarded to its
25 : successor. Simplification of the branch instruction is performed by
26 : underlying infrastructure so branch can be converted to simplejump or
27 : eliminated).
28 : - Cross jumping (tail merging)
29 : - Conditional jump-around-simplejump simplification
30 : - Basic block merging. */
31 :
32 : #include "config.h"
33 : #include "system.h"
34 : #include "coretypes.h"
35 : #include "backend.h"
36 : #include "target.h"
37 : #include "rtl.h"
38 : #include "tree.h"
39 : #include "cfghooks.h"
40 : #include "df.h"
41 : #include "memmodel.h"
42 : #include "tm_p.h"
43 : #include "insn-config.h"
44 : #include "emit-rtl.h"
45 : #include "cselib.h"
46 : #include "tree-pass.h"
47 : #include "cfgloop.h"
48 : #include "cfgrtl.h"
49 : #include "cfganal.h"
50 : #include "cfgbuild.h"
51 : #include "cfgcleanup.h"
52 : #include "dce.h"
53 : #include "dbgcnt.h"
54 : #include "rtl-iter.h"
55 : #include "regs.h"
56 : #include "function-abi.h"
57 :
58 : #define FORWARDER_BLOCK_P(BB) ((BB)->flags & BB_FORWARDER_BLOCK)
59 :
60 : /* Set to true when we are running first pass of try_optimize_cfg loop. */
61 : static bool first_pass;
62 :
63 : /* Set to true if crossjumps occurred in the latest run of try_optimize_cfg. */
64 : static bool crossjumps_occurred;
65 :
66 : /* Set to true if we couldn't run an optimization due to stale liveness
67 : information; we should run df_analyze to enable more opportunities. */
68 : static bool block_was_dirty;
69 :
70 : static bool try_crossjump_to_edge (int, edge, edge, enum replace_direction);
71 : static bool try_crossjump_bb (int, basic_block);
72 : static bool outgoing_edges_match (int, basic_block, basic_block);
73 : static enum replace_direction old_insns_match_p (int, rtx_insn *, rtx_insn *);
74 :
75 : static void merge_blocks_move_predecessor_nojumps (basic_block, basic_block);
76 : static void merge_blocks_move_successor_nojumps (basic_block, basic_block);
77 : static bool try_optimize_cfg (int);
78 : static bool try_simplify_condjump (basic_block);
79 : static bool try_forward_edges (int, basic_block);
80 : static edge thread_jump (edge, basic_block);
81 : static bool mark_effect (rtx, bitmap);
82 : static void notice_new_block (basic_block);
83 : static void update_forwarder_flag (basic_block);
84 : static void merge_memattrs (rtx, rtx);
85 :
86 : /* Set flags for newly created block. */
87 :
88 : static void
89 20936 : notice_new_block (basic_block bb)
90 : {
91 20936 : if (!bb)
92 : return;
93 :
94 14930 : if (forwarder_block_p (bb))
95 14930 : bb->flags |= BB_FORWARDER_BLOCK;
96 : }
97 :
98 : /* Recompute forwarder flag after block has been modified. */
99 :
100 : static void
101 315831854 : update_forwarder_flag (basic_block bb)
102 : {
103 315831854 : if (forwarder_block_p (bb))
104 16680042 : bb->flags |= BB_FORWARDER_BLOCK;
105 : else
106 299151812 : bb->flags &= ~BB_FORWARDER_BLOCK;
107 315831854 : }
108 :
109 : /* Simplify a conditional jump around an unconditional jump.
110 : Return true if something changed. */
111 :
112 : static bool
113 34685437 : try_simplify_condjump (basic_block cbranch_block)
114 : {
115 34685437 : basic_block jump_block, jump_dest_block, cbranch_dest_block;
116 34685437 : edge cbranch_jump_edge, cbranch_fallthru_edge;
117 34685437 : rtx_insn *cbranch_insn;
118 :
119 : /* Verify that there are exactly two successors. */
120 34685437 : if (EDGE_COUNT (cbranch_block->succs) != 2)
121 : return false;
122 :
123 : /* Verify that we've got a normal conditional branch at the end
124 : of the block. */
125 17401900 : cbranch_insn = BB_END (cbranch_block);
126 17401900 : if (!any_condjump_p (cbranch_insn))
127 : return false;
128 :
129 15262445 : cbranch_fallthru_edge = FALLTHRU_EDGE (cbranch_block);
130 15262445 : cbranch_jump_edge = BRANCH_EDGE (cbranch_block);
131 :
132 : /* The next block must not have multiple predecessors, must not
133 : be the last block in the function, and must contain just the
134 : unconditional jump. */
135 15262445 : jump_block = cbranch_fallthru_edge->dest;
136 49940687 : if (!single_pred_p (jump_block)
137 13576409 : || jump_block->next_bb == EXIT_BLOCK_PTR_FOR_FN (cfun)
138 28674192 : || !FORWARDER_BLOCK_P (jump_block))
139 : return false;
140 1728105 : jump_dest_block = single_succ (jump_block);
141 :
142 : /* If we are partitioning hot/cold basic blocks, we don't want to
143 : mess up unconditional or indirect jumps that cross between hot
144 : and cold sections.
145 :
146 : Basic block partitioning may result in some jumps that appear to
147 : be optimizable (or blocks that appear to be mergeable), but which really
148 : must be left untouched (they are required to make it safely across
149 : partition boundaries). See the comments at the top of
150 : bb-reorder.cc:partition_hot_cold_basic_blocks for complete details. */
151 :
152 1728105 : if (BB_PARTITION (jump_block) != BB_PARTITION (jump_dest_block)
153 1688322 : || (cbranch_jump_edge->flags & EDGE_CROSSING))
154 : return false;
155 :
156 : /* The conditional branch must target the block after the
157 : unconditional branch. */
158 1446208 : cbranch_dest_block = cbranch_jump_edge->dest;
159 :
160 1446208 : if (cbranch_dest_block == EXIT_BLOCK_PTR_FOR_FN (cfun)
161 1446208 : || jump_dest_block == EXIT_BLOCK_PTR_FOR_FN (cfun)
162 2891631 : || !can_fallthru (jump_block, cbranch_dest_block))
163 1439013 : return false;
164 :
165 : /* Invert the conditional branch. */
166 7195 : if (!invert_jump (as_a <rtx_jump_insn *> (cbranch_insn),
167 7195 : block_label (jump_dest_block), 0))
168 : return false;
169 :
170 7195 : if (dump_file)
171 1 : fprintf (dump_file, "Simplifying condjump %i around jump %i\n",
172 1 : INSN_UID (cbranch_insn), INSN_UID (BB_END (jump_block)));
173 :
174 : /* Success. Update the CFG to match. Note that after this point
175 : the edge variable names appear backwards; the redirection is done
176 : this way to preserve edge profile data. */
177 7195 : cbranch_jump_edge = redirect_edge_succ_nodup (cbranch_jump_edge,
178 : cbranch_dest_block);
179 7195 : cbranch_fallthru_edge = redirect_edge_succ_nodup (cbranch_fallthru_edge,
180 : jump_dest_block);
181 7195 : cbranch_jump_edge->flags |= EDGE_FALLTHRU;
182 7195 : cbranch_fallthru_edge->flags &= ~EDGE_FALLTHRU;
183 7195 : update_br_prob_note (cbranch_block);
184 :
185 : /* Delete the block with the unconditional jump, and clean up the mess. */
186 7195 : delete_basic_block (jump_block);
187 7195 : tidy_fallthru_edge (cbranch_jump_edge);
188 7195 : update_forwarder_flag (cbranch_block);
189 :
190 7195 : return true;
191 : }
192 :
193 : /* Attempt to prove that operation is NOOP using CSElib or mark the effect
194 : on register. Used by jump threading. */
195 :
196 : static bool
197 33795852 : mark_effect (rtx exp, regset nonequal)
198 : {
199 33795852 : rtx dest;
200 33795852 : switch (GET_CODE (exp))
201 : {
202 : /* In case we do clobber the register, mark it as equal, as we know the
203 : value is dead so it don't have to match. */
204 2472685 : case CLOBBER:
205 2472685 : dest = XEXP (exp, 0);
206 2472685 : if (REG_P (dest))
207 2441013 : bitmap_clear_range (nonequal, REGNO (dest), REG_NREGS (dest));
208 : return false;
209 :
210 11099895 : case SET:
211 11099895 : if (cselib_redundant_set_p (exp))
212 : return false;
213 10917248 : dest = SET_DEST (exp);
214 10917248 : if (dest == pc_rtx)
215 : return false;
216 10910057 : if (!REG_P (dest))
217 : return true;
218 10364121 : bitmap_set_range (nonequal, REGNO (dest), REG_NREGS (dest));
219 10364121 : return false;
220 :
221 : default:
222 : return false;
223 : }
224 : }
225 :
226 : /* Return true if X contains a register in NONEQUAL. */
227 : static bool
228 3601516 : mentions_nonequal_regs (const_rtx x, regset nonequal)
229 : {
230 3601516 : subrtx_iterator::array_type array;
231 7218378 : FOR_EACH_SUBRTX (iter, array, x, NONCONST)
232 : {
233 7211187 : const_rtx x = *iter;
234 7211187 : if (REG_P (x))
235 : {
236 3601757 : unsigned int end_regno = END_REGNO (x);
237 3609189 : for (unsigned int regno = REGNO (x); regno < end_regno; ++regno)
238 3601757 : if (REGNO_REG_SET_P (nonequal, regno))
239 3594325 : return true;
240 : }
241 : }
242 7191 : return false;
243 3601516 : }
244 :
245 : /* Attempt to prove that the basic block B will have no side effects and
246 : always continues in the same edge if reached via E. Return the edge
247 : if exist, NULL otherwise. */
248 :
249 : static edge
250 28414924 : thread_jump (edge e, basic_block b)
251 : {
252 28414924 : rtx set1, set2, cond1, cond2;
253 28414924 : rtx_insn *insn;
254 28414924 : enum rtx_code code1, code2, reversed_code2;
255 28414924 : bool reverse1 = false;
256 28414924 : unsigned i;
257 28414924 : regset nonequal;
258 28414924 : bool failed = false;
259 :
260 : /* Jump threading may cause fixup_partitions to introduce new crossing edges,
261 : which is not allowed after reload. */
262 28414924 : gcc_checking_assert (!reload_completed || !crtl->has_bb_partition);
263 :
264 28414924 : if (b->flags & BB_NONTHREADABLE_BLOCK)
265 : return NULL;
266 :
267 : /* At the moment, we do handle only conditional jumps, but later we may
268 : want to extend this code to tablejumps and others. */
269 45577615 : if (EDGE_COUNT (e->src->succs) != 2)
270 : return NULL;
271 17169303 : if (EDGE_COUNT (b->succs) != 2)
272 : {
273 7580534 : b->flags |= BB_NONTHREADABLE_BLOCK;
274 7580534 : return NULL;
275 : }
276 :
277 : /* Second branch must end with onlyjump, as we will eliminate the jump. */
278 9588769 : if (!any_condjump_p (BB_END (e->src)))
279 : return NULL;
280 :
281 8747151 : if (!any_condjump_p (BB_END (b)) || !onlyjump_p (BB_END (b)))
282 : {
283 649704 : b->flags |= BB_NONTHREADABLE_BLOCK;
284 649704 : return NULL;
285 : }
286 :
287 8097447 : set1 = pc_set (BB_END (e->src));
288 8097447 : set2 = pc_set (BB_END (b));
289 8097447 : if (((e->flags & EDGE_FALLTHRU) != 0)
290 8097447 : != (XEXP (SET_SRC (set1), 1) == pc_rtx))
291 4007446 : reverse1 = true;
292 :
293 8097447 : cond1 = XEXP (SET_SRC (set1), 0);
294 8097447 : cond2 = XEXP (SET_SRC (set2), 0);
295 8097447 : if (reverse1)
296 4007446 : code1 = reversed_comparison_code (cond1, BB_END (e->src));
297 : else
298 4090001 : code1 = GET_CODE (cond1);
299 :
300 8097447 : code2 = GET_CODE (cond2);
301 8097447 : reversed_code2 = reversed_comparison_code (cond2, BB_END (b));
302 :
303 8097447 : if (!comparison_dominates_p (code1, code2)
304 8097447 : && !comparison_dominates_p (code1, reversed_code2))
305 : return NULL;
306 :
307 : /* Ensure that the comparison operators are equivalent.
308 : ??? This is far too pessimistic. We should allow swapped operands,
309 : different CCmodes, or for example comparisons for interval, that
310 : dominate even when operands are not equivalent. */
311 6498370 : if (!rtx_equal_p (XEXP (cond1, 0), XEXP (cond2, 0))
312 6498370 : || !rtx_equal_p (XEXP (cond1, 1), XEXP (cond2, 1)))
313 928174 : return NULL;
314 :
315 : /* Punt if BB_END (e->src) is doloop-like conditional jump that modifies
316 : the registers used in cond1. */
317 5570196 : if (modified_in_p (cond1, BB_END (e->src)))
318 : return NULL;
319 :
320 : /* Short circuit cases where block B contains some side effects, as we can't
321 : safely bypass it. */
322 64337062 : for (insn = NEXT_INSN (BB_HEAD (b)); insn != NEXT_INSN (BB_END (b));
323 53196670 : insn = NEXT_INSN (insn))
324 54619414 : if (INSN_P (insn) && side_effects_p (PATTERN (insn)))
325 : {
326 1422744 : b->flags |= BB_NONTHREADABLE_BLOCK;
327 1422744 : return NULL;
328 : }
329 :
330 4147452 : cselib_init (0);
331 :
332 : /* First process all values computed in the source basic block. */
333 59856184 : for (insn = NEXT_INSN (BB_HEAD (e->src));
334 59856184 : insn != NEXT_INSN (BB_END (e->src));
335 55708732 : insn = NEXT_INSN (insn))
336 55708732 : if (INSN_P (insn))
337 51983668 : cselib_process_insn (insn);
338 :
339 4147452 : nonequal = BITMAP_ALLOC (NULL);
340 4147452 : CLEAR_REG_SET (nonequal);
341 :
342 : /* Now assume that we've continued by the edge E to B and continue
343 : processing as if it were same basic block.
344 : Our goal is to prove that whole block is an NOOP. */
345 :
346 38455647 : for (insn = NEXT_INSN (BB_HEAD (b));
347 38455647 : insn != NEXT_INSN (BB_END (b)) && !failed;
348 34308195 : insn = NEXT_INSN (insn))
349 : {
350 : /* cond2 must not mention any register that is not equal to the
351 : former block. Check this before processing that instruction,
352 : as BB_END (b) could contain also clobbers. */
353 37902520 : if (insn == BB_END (b)
354 37902520 : && mentions_nonequal_regs (cond2, nonequal))
355 3594325 : goto failed_exit;
356 :
357 34308195 : if (INSN_P (insn))
358 : {
359 31225153 : rtx pat = PATTERN (insn);
360 :
361 31225153 : if (GET_CODE (pat) == PARALLEL)
362 : {
363 7536549 : for (i = 0; i < (unsigned)XVECLEN (pat, 0); i++)
364 5053624 : failed |= mark_effect (XVECEXP (pat, 0, i), nonequal);
365 : }
366 : else
367 28742228 : failed |= mark_effect (pat, nonequal);
368 : }
369 :
370 34308195 : cselib_process_insn (insn);
371 : }
372 :
373 : /* Later we should clear nonequal of dead registers. So far we don't
374 : have life information in cfg_cleanup. */
375 553127 : if (failed)
376 : {
377 545936 : b->flags |= BB_NONTHREADABLE_BLOCK;
378 545936 : goto failed_exit;
379 : }
380 :
381 7191 : if (!REG_SET_EMPTY_P (nonequal))
382 579 : goto failed_exit;
383 :
384 6612 : BITMAP_FREE (nonequal);
385 6612 : cselib_finish ();
386 6612 : if ((comparison_dominates_p (code1, code2) != 0)
387 6612 : != (XEXP (SET_SRC (set2), 1) == pc_rtx))
388 4413 : return BRANCH_EDGE (b);
389 : else
390 2199 : return FALLTHRU_EDGE (b);
391 :
392 4140840 : failed_exit:
393 4140840 : BITMAP_FREE (nonequal);
394 4140840 : cselib_finish ();
395 4140840 : return NULL;
396 : }
397 :
398 : /* Attempt to forward edges leaving basic block B.
399 : Return true if successful. */
400 :
401 : static bool
402 404209576 : try_forward_edges (int mode, basic_block b)
403 : {
404 404209576 : bool changed = false;
405 404209576 : edge_iterator ei;
406 404209576 : edge e, *threaded_edges = NULL;
407 :
408 1012691689 : for (ei = ei_start (b->succs); (e = ei_safe_edge (ei)); )
409 : {
410 608482113 : basic_block target, first;
411 608482113 : location_t goto_locus;
412 608482113 : int counter;
413 608482113 : bool threaded = false;
414 608482113 : int nthreaded_edges = 0;
415 608482113 : bool may_thread = first_pass || (b->flags & BB_MODIFIED) != 0;
416 608482113 : bool new_target_threaded = false;
417 :
418 : /* Skip complex edges because we don't know how to update them.
419 :
420 : Still handle fallthru edges, as we can succeed to forward fallthru
421 : edge to the same place as the branch edge of conditional branch
422 : and turn conditional branch to an unconditional branch. */
423 608482113 : if (e->flags & EDGE_COMPLEX)
424 : {
425 34233872 : ei_next (&ei);
426 34233872 : continue;
427 : }
428 :
429 574248241 : target = first = e->dest;
430 574248241 : counter = NUM_FIXED_BLOCKS;
431 574248241 : goto_locus = e->goto_locus;
432 :
433 603837934 : while (counter < n_basic_blocks_for_fn (cfun))
434 : {
435 603418746 : basic_block new_target = NULL;
436 603418746 : may_thread |= (target->flags & BB_MODIFIED) != 0;
437 :
438 603418746 : if (FORWARDER_BLOCK_P (target)
439 642475738 : && single_succ (target) != EXIT_BLOCK_PTR_FOR_FN (cfun))
440 : {
441 : /* Bypass trivial infinite loops. */
442 29772359 : new_target = single_succ (target);
443 29772359 : if (target == new_target)
444 : counter = n_basic_blocks_for_fn (cfun);
445 29491884 : else if (!optimize)
446 : {
447 : /* When not optimizing, ensure that edges or forwarder
448 : blocks with different locus are not optimized out. */
449 1189538 : location_t new_locus = single_succ_edge (target)->goto_locus;
450 1189538 : location_t locus = goto_locus;
451 :
452 1189538 : if (LOCATION_LOCUS (new_locus) != UNKNOWN_LOCATION
453 474531 : && LOCATION_LOCUS (locus) != UNKNOWN_LOCATION
454 1501188 : && new_locus != locus)
455 : new_target = NULL;
456 : else
457 : {
458 1009226 : if (LOCATION_LOCUS (new_locus) != UNKNOWN_LOCATION)
459 294219 : locus = new_locus;
460 :
461 1009226 : rtx_insn *last = BB_END (target);
462 1009226 : if (DEBUG_INSN_P (last))
463 6 : last = prev_nondebug_insn (last);
464 1009226 : if (last && INSN_P (last))
465 500162 : new_locus = INSN_LOCATION (last);
466 : else
467 : new_locus = UNKNOWN_LOCATION;
468 :
469 500162 : if (LOCATION_LOCUS (new_locus) != UNKNOWN_LOCATION
470 483418 : && LOCATION_LOCUS (locus) != UNKNOWN_LOCATION
471 1378890 : && new_locus != locus)
472 : new_target = NULL;
473 : else
474 : {
475 1000799 : if (LOCATION_LOCUS (new_locus) != UNKNOWN_LOCATION)
476 474991 : locus = new_locus;
477 :
478 : goto_locus = locus;
479 : }
480 : }
481 : }
482 : }
483 :
484 : /* Allow to thread only over one edge at time to simplify updating
485 : of probabilities. */
486 573646387 : else if ((mode & CLEANUP_THREADING) && may_thread)
487 : {
488 28414924 : edge t = thread_jump (e, target);
489 28414924 : if (t)
490 : {
491 6612 : if (!threaded_edges)
492 6543 : threaded_edges = XNEWVEC (edge,
493 : n_basic_blocks_for_fn (cfun));
494 : else
495 : {
496 : int i;
497 :
498 : /* Detect an infinite loop across blocks not
499 : including the start block. */
500 216 : for (i = 0; i < nthreaded_edges; ++i)
501 161 : if (threaded_edges[i] == t)
502 : break;
503 69 : if (i < nthreaded_edges)
504 : {
505 14 : counter = n_basic_blocks_for_fn (cfun);
506 14 : break;
507 : }
508 : }
509 :
510 : /* Detect an infinite loop across the start block. */
511 6598 : if (t->dest == b)
512 : break;
513 :
514 6073 : gcc_assert (nthreaded_edges
515 : < (n_basic_blocks_for_fn (cfun)
516 : - NUM_FIXED_BLOCKS));
517 6073 : threaded_edges[nthreaded_edges++] = t;
518 :
519 6073 : new_target = t->dest;
520 6073 : new_target_threaded = true;
521 : }
522 : }
523 :
524 29589693 : if (!new_target)
525 : break;
526 :
527 29589693 : counter++;
528 : /* Do not turn non-crossing jump to crossing. Depending on target
529 : it may require different instruction pattern. */
530 29589693 : if ((e->flags & EDGE_CROSSING)
531 29555720 : || BB_PARTITION (first) == BB_PARTITION (new_target))
532 : {
533 15372954 : target = new_target;
534 15372954 : threaded |= new_target_threaded;
535 : }
536 : }
537 :
538 574248241 : if (counter >= n_basic_blocks_for_fn (cfun))
539 : {
540 419202 : if (dump_file)
541 4 : fprintf (dump_file, "Infinite loop in BB %i.\n",
542 : target->index);
543 : }
544 573829039 : else if (target == first)
545 : ; /* We didn't do anything. */
546 : else
547 : {
548 : /* Save the values now, as the edge may get removed. */
549 14178748 : profile_count edge_count = e->count ();
550 14178748 : int n = 0;
551 :
552 14178748 : e->goto_locus = goto_locus;
553 :
554 : /* Don't force if target is exit block. */
555 14178748 : if (threaded && target != EXIT_BLOCK_PTR_FOR_FN (cfun))
556 : {
557 6006 : notice_new_block (redirect_edge_and_branch_force (e, target));
558 6006 : if (dump_file)
559 0 : fprintf (dump_file, "Conditionals threaded.\n");
560 : }
561 14172742 : else if (!redirect_edge_and_branch (e, target))
562 : {
563 7599237 : if (dump_file)
564 187 : fprintf (dump_file,
565 : "Forwarding edge %i->%i to %i failed.\n",
566 187 : b->index, e->dest->index, target->index);
567 7599237 : ei_next (&ei);
568 7599237 : continue;
569 : }
570 :
571 : /* We successfully forwarded the edge. Now update profile
572 : data: for each edge we traversed in the chain, remove
573 : the original edge's execution count. */
574 6688934 : do
575 : {
576 6688934 : edge t;
577 :
578 6688934 : if (!single_succ_p (first))
579 : {
580 6059 : gcc_assert (n < nthreaded_edges);
581 6059 : t = threaded_edges [n++];
582 6059 : gcc_assert (t->src == first);
583 6059 : update_bb_profile_for_threading (first, edge_count, t);
584 6059 : update_br_prob_note (first);
585 : }
586 : else
587 : {
588 6682875 : first->count -= edge_count;
589 : /* It is possible that as the result of
590 : threading we've removed edge as it is
591 : threaded to the fallthru edge. Avoid
592 : getting out of sync. */
593 6682875 : if (n < nthreaded_edges
594 0 : && first == threaded_edges [n]->src)
595 0 : n++;
596 6682875 : t = single_succ_edge (first);
597 : }
598 :
599 6688934 : first = t->dest;
600 : }
601 6688934 : while (first != target);
602 :
603 6579511 : changed = true;
604 6579511 : continue;
605 6579511 : }
606 560069493 : ei_next (&ei);
607 : }
608 :
609 404209576 : free (threaded_edges);
610 404209576 : return changed;
611 : }
612 :
613 :
614 : /* Blocks A and B are to be merged into a single block. A has no incoming
615 : fallthru edge, so it can be moved before B without adding or modifying
616 : any jumps (aside from the jump from A to B). */
617 :
618 : static void
619 21772 : merge_blocks_move_predecessor_nojumps (basic_block a, basic_block b)
620 : {
621 21772 : rtx_insn *barrier;
622 :
623 : /* If we are partitioning hot/cold basic blocks, we don't want to
624 : mess up unconditional or indirect jumps that cross between hot
625 : and cold sections.
626 :
627 : Basic block partitioning may result in some jumps that appear to
628 : be optimizable (or blocks that appear to be mergeable), but which really
629 : must be left untouched (they are required to make it safely across
630 : partition boundaries). See the comments at the top of
631 : bb-reorder.cc:partition_hot_cold_basic_blocks for complete details. */
632 :
633 21772 : if (BB_PARTITION (a) != BB_PARTITION (b))
634 : return;
635 :
636 21772 : barrier = next_nonnote_insn (BB_END (a));
637 21772 : gcc_assert (BARRIER_P (barrier));
638 21772 : delete_insn (barrier);
639 :
640 : /* Scramble the insn chain. */
641 21772 : if (BB_END (a) != PREV_INSN (BB_HEAD (b)))
642 21743 : reorder_insns_nobb (BB_HEAD (a), BB_END (a), PREV_INSN (BB_HEAD (b)));
643 21772 : df_set_bb_dirty (a);
644 :
645 21772 : if (dump_file)
646 0 : fprintf (dump_file, "Moved block %d before %d and merged.\n",
647 : a->index, b->index);
648 :
649 : /* Swap the records for the two blocks around. */
650 :
651 21772 : unlink_block (a);
652 21772 : link_block (a, b->prev_bb);
653 :
654 : /* Now blocks A and B are contiguous. Merge them. */
655 21772 : merge_blocks (a, b);
656 : }
657 :
658 : /* Blocks A and B are to be merged into a single block. B has no outgoing
659 : fallthru edge, so it can be moved after A without adding or modifying
660 : any jumps (aside from the jump from A to B). */
661 :
662 : static void
663 31280 : merge_blocks_move_successor_nojumps (basic_block a, basic_block b)
664 : {
665 31280 : rtx_insn *barrier, *real_b_end;
666 31280 : rtx_insn *label;
667 31280 : rtx_jump_table_data *table;
668 :
669 : /* If we are partitioning hot/cold basic blocks, we don't want to
670 : mess up unconditional or indirect jumps that cross between hot
671 : and cold sections.
672 :
673 : Basic block partitioning may result in some jumps that appear to
674 : be optimizable (or blocks that appear to be mergeable), but which really
675 : must be left untouched (they are required to make it safely across
676 : partition boundaries). See the comments at the top of
677 : bb-reorder.cc:partition_hot_cold_basic_blocks for complete details. */
678 :
679 31280 : if (BB_PARTITION (a) != BB_PARTITION (b))
680 0 : return;
681 :
682 31280 : real_b_end = BB_END (b);
683 :
684 : /* If there is a jump table following block B temporarily add the jump table
685 : to block B so that it will also be moved to the correct location. */
686 31280 : if (tablejump_p (BB_END (b), &label, &table)
687 31280 : && prev_active_insn (label) == BB_END (b))
688 : {
689 0 : BB_END (b) = table;
690 : }
691 :
692 : /* There had better have been a barrier there. Delete it. */
693 31280 : barrier = NEXT_INSN (BB_END (b));
694 31280 : if (barrier && BARRIER_P (barrier))
695 31280 : delete_insn (barrier);
696 :
697 :
698 : /* Scramble the insn chain. */
699 31280 : reorder_insns_nobb (BB_HEAD (b), BB_END (b), BB_END (a));
700 :
701 : /* Restore the real end of b. */
702 31280 : BB_END (b) = real_b_end;
703 :
704 31280 : if (dump_file)
705 20 : fprintf (dump_file, "Moved block %d after %d and merged.\n",
706 : b->index, a->index);
707 :
708 : /* Now blocks A and B are contiguous. Merge them. */
709 31280 : merge_blocks (a, b);
710 : }
711 :
712 : /* Attempt to merge basic blocks that are potentially non-adjacent.
713 : Return NULL iff the attempt failed, otherwise return basic block
714 : where cleanup_cfg should continue. Because the merging commonly
715 : moves basic block away or introduces another optimization
716 : possibility, return basic block just before B so cleanup_cfg don't
717 : need to iterate.
718 :
719 : It may be good idea to return basic block before C in the case
720 : C has been moved after B and originally appeared earlier in the
721 : insn sequence, but we have no information available about the
722 : relative ordering of these two. Hopefully it is not too common. */
723 :
724 : static basic_block
725 7022866 : merge_blocks_move (edge e, basic_block b, basic_block c, int mode)
726 : {
727 7022866 : basic_block next;
728 :
729 : /* If we are partitioning hot/cold basic blocks, we don't want to
730 : mess up unconditional or indirect jumps that cross between hot
731 : and cold sections.
732 :
733 : Basic block partitioning may result in some jumps that appear to
734 : be optimizable (or blocks that appear to be mergeable), but which really
735 : must be left untouched (they are required to make it safely across
736 : partition boundaries). See the comments at the top of
737 : bb-reorder.cc:partition_hot_cold_basic_blocks for complete details. */
738 :
739 7022866 : if (BB_PARTITION (b) != BB_PARTITION (c))
740 : return NULL;
741 :
742 : /* If B has a fallthru edge to C, no need to move anything. */
743 6632105 : if (e->flags & EDGE_FALLTHRU)
744 : {
745 3802939 : int b_index = b->index, c_index = c->index;
746 :
747 : /* Protect the loop latches. */
748 3802939 : if (current_loops && c->loop_father->latch == c)
749 : return NULL;
750 :
751 3758118 : merge_blocks (b, c);
752 3758118 : update_forwarder_flag (b);
753 :
754 3758118 : if (dump_file)
755 836 : fprintf (dump_file, "Merged %d and %d without moving.\n",
756 : b_index, c_index);
757 :
758 4867639 : return b->prev_bb == ENTRY_BLOCK_PTR_FOR_FN (cfun) ? b : b->prev_bb;
759 : }
760 :
761 : /* Otherwise we will need to move code around. Do that only if expensive
762 : transformations are allowed. */
763 2829166 : else if (mode & CLEANUP_EXPENSIVE)
764 : {
765 937597 : edge tmp_edge, b_fallthru_edge;
766 937597 : bool c_has_outgoing_fallthru;
767 937597 : bool b_has_incoming_fallthru;
768 :
769 : /* Avoid overactive code motion, as the forwarder blocks should be
770 : eliminated by edge redirection instead. One exception might have
771 : been if B is a forwarder block and C has no fallthru edge, but
772 : that should be cleaned up by bb-reorder instead. */
773 937597 : if (FORWARDER_BLOCK_P (b) || FORWARDER_BLOCK_P (c))
774 : return NULL;
775 :
776 : /* We must make sure to not munge nesting of lexical blocks,
777 : and loop notes. This is done by squeezing out all the notes
778 : and leaving them there to lie. Not ideal, but functional. */
779 :
780 55232 : tmp_edge = find_fallthru_edge (c->succs);
781 55232 : c_has_outgoing_fallthru = (tmp_edge != NULL);
782 :
783 55232 : tmp_edge = find_fallthru_edge (b->preds);
784 55232 : b_has_incoming_fallthru = (tmp_edge != NULL);
785 55232 : b_fallthru_edge = tmp_edge;
786 55232 : next = b->prev_bb;
787 55232 : if (next == c)
788 57 : next = next->prev_bb;
789 :
790 : /* Otherwise, we're going to try to move C after B. If C does
791 : not have an outgoing fallthru, then it can be moved
792 : immediately after B without introducing or modifying jumps. */
793 55232 : if (! c_has_outgoing_fallthru)
794 : {
795 31280 : merge_blocks_move_successor_nojumps (b, c);
796 31280 : return next == ENTRY_BLOCK_PTR_FOR_FN (cfun) ? next->next_bb : next;
797 : }
798 :
799 : /* If B does not have an incoming fallthru, then it can be moved
800 : immediately before C without introducing or modifying jumps.
801 : C cannot be the first block, so we do not have to worry about
802 : accessing a non-existent block. */
803 :
804 23952 : if (b_has_incoming_fallthru)
805 : {
806 21756 : basic_block bb;
807 :
808 21756 : if (b_fallthru_edge->src == ENTRY_BLOCK_PTR_FOR_FN (cfun))
809 : return NULL;
810 19576 : bb = force_nonfallthru (b_fallthru_edge);
811 19576 : if (bb)
812 14930 : notice_new_block (bb);
813 : }
814 :
815 21772 : merge_blocks_move_predecessor_nojumps (b, c);
816 21772 : return next == ENTRY_BLOCK_PTR_FOR_FN (cfun) ? next->next_bb : next;
817 : }
818 :
819 : return NULL;
820 : }
821 :
822 :
823 : /* Removes the memory attributes of MEM expression
824 : if they are not equal. */
825 :
826 : static void
827 148255710 : merge_memattrs (rtx x, rtx y)
828 : {
829 148255710 : int i;
830 148255710 : int j;
831 148255710 : enum rtx_code code;
832 148255710 : const char *fmt;
833 :
834 148255710 : if (x == y)
835 : return;
836 110635328 : if (x == 0 || y == 0)
837 : return;
838 :
839 110597079 : code = GET_CODE (x);
840 :
841 110597079 : if (code != GET_CODE (y))
842 : return;
843 :
844 110597067 : if (GET_MODE (x) != GET_MODE (y))
845 : return;
846 :
847 110593891 : if (code == MEM && !mem_attrs_eq_p (MEM_ATTRS (x), MEM_ATTRS (y)))
848 : {
849 46599 : if (! MEM_ATTRS (x))
850 769 : MEM_ATTRS (y) = 0;
851 45830 : else if (! MEM_ATTRS (y))
852 1322 : MEM_ATTRS (x) = 0;
853 : else
854 : {
855 44508 : if (MEM_ALIAS_SET (x) != MEM_ALIAS_SET (y))
856 : {
857 2970 : set_mem_alias_set (x, 0);
858 2970 : set_mem_alias_set (y, 0);
859 : }
860 :
861 44508 : if (! mem_expr_equal_p (MEM_EXPR (x), MEM_EXPR (y)))
862 : {
863 43678 : set_mem_expr (x, 0);
864 43678 : set_mem_expr (y, 0);
865 43678 : clear_mem_offset (x);
866 43678 : clear_mem_offset (y);
867 : }
868 830 : else if (MEM_OFFSET_KNOWN_P (x) != MEM_OFFSET_KNOWN_P (y)
869 830 : || (MEM_OFFSET_KNOWN_P (x)
870 0 : && maybe_ne (MEM_OFFSET (x), MEM_OFFSET (y))))
871 : {
872 0 : clear_mem_offset (x);
873 0 : clear_mem_offset (y);
874 : }
875 :
876 51233 : if (!MEM_SIZE_KNOWN_P (x))
877 214 : clear_mem_size (y);
878 50832 : else if (!MEM_SIZE_KNOWN_P (y))
879 0 : clear_mem_size (x);
880 44294 : else if (known_le (MEM_SIZE (x), MEM_SIZE (y)))
881 44250 : set_mem_size (x, MEM_SIZE (y));
882 44 : else if (known_le (MEM_SIZE (y), MEM_SIZE (x)))
883 44 : set_mem_size (y, MEM_SIZE (x));
884 : else
885 : {
886 : /* The sizes aren't ordered, so we can't merge them. */
887 : clear_mem_size (x);
888 : clear_mem_size (y);
889 : }
890 :
891 57984 : set_mem_align (x, MIN (MEM_ALIGN (x), MEM_ALIGN (y)));
892 51267 : set_mem_align (y, MEM_ALIGN (x));
893 : }
894 : }
895 110593891 : if (code == MEM)
896 : {
897 6095882 : if (MEM_READONLY_P (x) != MEM_READONLY_P (y))
898 : {
899 0 : MEM_READONLY_P (x) = 0;
900 0 : MEM_READONLY_P (y) = 0;
901 : }
902 6095882 : if (MEM_NOTRAP_P (x) != MEM_NOTRAP_P (y))
903 : {
904 191 : MEM_NOTRAP_P (x) = 0;
905 191 : MEM_NOTRAP_P (y) = 0;
906 : }
907 6095882 : if (MEM_VOLATILE_P (x) != MEM_VOLATILE_P (y))
908 : {
909 150 : MEM_VOLATILE_P (x) = 1;
910 150 : MEM_VOLATILE_P (y) = 1;
911 : }
912 : }
913 :
914 110593891 : fmt = GET_RTX_FORMAT (code);
915 336078785 : for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
916 : {
917 225484894 : switch (fmt[i])
918 : {
919 384692 : case 'E':
920 : /* Two vectors must have the same length. */
921 384692 : if (XVECLEN (x, i) != XVECLEN (y, i))
922 : return;
923 :
924 1137264 : for (j = 0; j < XVECLEN (x, i); j++)
925 752572 : merge_memattrs (XVECEXP (x, i, j), XVECEXP (y, i, j));
926 :
927 : break;
928 :
929 138760928 : case 'e':
930 138760928 : merge_memattrs (XEXP (x, i), XEXP (y, i));
931 : }
932 : }
933 : return;
934 : }
935 :
936 :
937 : /* Checks if patterns P1 and P2 are equivalent, apart from the possibly
938 : different single sets S1 and S2. */
939 :
940 : static bool
941 2 : equal_different_set_p (rtx p1, rtx s1, rtx p2, rtx s2)
942 : {
943 2 : int i;
944 2 : rtx e1, e2;
945 :
946 2 : if (p1 == s1 && p2 == s2)
947 : return true;
948 :
949 0 : if (GET_CODE (p1) != PARALLEL || GET_CODE (p2) != PARALLEL)
950 : return false;
951 :
952 0 : if (XVECLEN (p1, 0) != XVECLEN (p2, 0))
953 : return false;
954 :
955 0 : for (i = 0; i < XVECLEN (p1, 0); i++)
956 : {
957 0 : e1 = XVECEXP (p1, 0, i);
958 0 : e2 = XVECEXP (p2, 0, i);
959 0 : if (e1 == s1 && e2 == s2)
960 0 : continue;
961 0 : if (reload_completed
962 0 : ? rtx_renumbered_equal_p (e1, e2) : rtx_equal_p (e1, e2))
963 0 : continue;
964 :
965 : return false;
966 : }
967 :
968 : return true;
969 : }
970 :
971 :
972 : /* NOTE1 is the REG_EQUAL note, if any, attached to an insn
973 : that is a single_set with a SET_SRC of SRC1. Similarly
974 : for NOTE2/SRC2.
975 :
976 : So effectively NOTE1/NOTE2 are an alternate form of
977 : SRC1/SRC2 respectively.
978 :
979 : Return nonzero if SRC1 or NOTE1 has the same constant
980 : integer value as SRC2 or NOTE2. Else return zero. */
981 : static int
982 7735547 : values_equal_p (rtx note1, rtx note2, rtx src1, rtx src2)
983 : {
984 7735547 : if (note1
985 7735547 : && note2
986 1283002 : && CONST_INT_P (XEXP (note1, 0))
987 7792126 : && rtx_equal_p (XEXP (note1, 0), XEXP (note2, 0)))
988 : return 1;
989 :
990 7735547 : if (!note1
991 7735547 : && !note2
992 5983377 : && CONST_INT_P (src1)
993 2535204 : && CONST_INT_P (src2)
994 10168213 : && rtx_equal_p (src1, src2))
995 : return 1;
996 :
997 7735547 : if (note1
998 1557821 : && CONST_INT_P (src2)
999 7879995 : && rtx_equal_p (XEXP (note1, 0), src2))
1000 : return 1;
1001 :
1002 7735547 : if (note2
1003 1477351 : && CONST_INT_P (src1)
1004 7804269 : && rtx_equal_p (XEXP (note2, 0), src1))
1005 : return 1;
1006 :
1007 : return 0;
1008 : }
1009 :
1010 : /* Examine register notes on I1 and I2 and return:
1011 : - dir_forward if I1 can be replaced by I2, or
1012 : - dir_backward if I2 can be replaced by I1, or
1013 : - dir_both if both are the case. */
1014 :
1015 : static enum replace_direction
1016 13966723 : can_replace_by (rtx_insn *i1, rtx_insn *i2)
1017 : {
1018 13966723 : rtx s1, s2, d1, d2, src1, src2, note1, note2;
1019 13966723 : bool c1, c2;
1020 :
1021 : /* Check for 2 sets. */
1022 13966723 : s1 = single_set (i1);
1023 13966723 : s2 = single_set (i2);
1024 13966723 : if (s1 == NULL_RTX || s2 == NULL_RTX)
1025 : return dir_none;
1026 :
1027 : /* Check that the 2 sets set the same dest. */
1028 13192177 : d1 = SET_DEST (s1);
1029 13192177 : d2 = SET_DEST (s2);
1030 26384354 : if (!(reload_completed
1031 13192177 : ? rtx_renumbered_equal_p (d1, d2) : rtx_equal_p (d1, d2)))
1032 : return dir_none;
1033 :
1034 : /* Find identical req_equiv or reg_equal note, which implies that the 2 sets
1035 : set dest to the same value. */
1036 7735547 : note1 = find_reg_equal_equiv_note (i1);
1037 7735547 : note2 = find_reg_equal_equiv_note (i2);
1038 :
1039 7735547 : src1 = SET_SRC (s1);
1040 7735547 : src2 = SET_SRC (s2);
1041 :
1042 7735547 : if (!values_equal_p (note1, note2, src1, src2))
1043 : return dir_none;
1044 :
1045 2 : if (!equal_different_set_p (PATTERN (i1), s1, PATTERN (i2), s2))
1046 : return dir_none;
1047 :
1048 : /* Although the 2 sets set dest to the same value, we cannot replace
1049 : (set (dest) (const_int))
1050 : by
1051 : (set (dest) (reg))
1052 : because we don't know if the reg is live and has the same value at the
1053 : location of replacement. */
1054 2 : c1 = CONST_INT_P (src1);
1055 2 : c2 = CONST_INT_P (src2);
1056 2 : if (c1 && c2)
1057 : return dir_both;
1058 2 : else if (c2)
1059 : return dir_forward;
1060 2 : else if (c1)
1061 : return dir_backward;
1062 :
1063 : return dir_none;
1064 : }
1065 :
1066 : /* Merges directions A and B. */
1067 :
1068 : static enum replace_direction
1069 23773927 : merge_dir (enum replace_direction a, enum replace_direction b)
1070 : {
1071 : /* Implements the following table:
1072 : |bo fw bw no
1073 : ---+-----------
1074 : bo |bo fw bw no
1075 : fw |-- fw no no
1076 : bw |-- -- bw no
1077 : no |-- -- -- no. */
1078 :
1079 0 : if (a == b)
1080 : return a;
1081 :
1082 16336377 : if (a == dir_both)
1083 : return b;
1084 3845733 : if (b == dir_both)
1085 0 : return a;
1086 :
1087 : return dir_none;
1088 : }
1089 :
1090 : /* Array of flags indexed by reg note kind, true if the given
1091 : reg note is CFA related. */
1092 : static const bool reg_note_cfa_p[] = {
1093 : #undef REG_CFA_NOTE
1094 : #define DEF_REG_NOTE(NAME) false,
1095 : #define REG_CFA_NOTE(NAME) true,
1096 : #include "reg-notes.def"
1097 : #undef REG_CFA_NOTE
1098 : #undef DEF_REG_NOTE
1099 : false
1100 : };
1101 :
1102 : /* Return true if I1 and I2 have identical CFA notes (the same order
1103 : and equivalent content). */
1104 :
1105 : static bool
1106 639438 : insns_have_identical_cfa_notes (rtx_insn *i1, rtx_insn *i2)
1107 : {
1108 639438 : rtx n1, n2;
1109 639438 : for (n1 = REG_NOTES (i1), n2 = REG_NOTES (i2); ;
1110 501341 : n1 = XEXP (n1, 1), n2 = XEXP (n2, 1))
1111 : {
1112 : /* Skip over reg notes not related to CFI information. */
1113 1667791 : while (n1 && !reg_note_cfa_p[REG_NOTE_KIND (n1)])
1114 25671 : n1 = XEXP (n1, 1);
1115 1165090 : while (n2 && !reg_note_cfa_p[REG_NOTE_KIND (n2)])
1116 24311 : n2 = XEXP (n2, 1);
1117 1140779 : if (n1 == NULL_RTX && n2 == NULL_RTX)
1118 : return true;
1119 622516 : if (n1 == NULL_RTX || n2 == NULL_RTX)
1120 : return false;
1121 617985 : if (XEXP (n1, 0) == XEXP (n2, 0))
1122 : ;
1123 617979 : else if (XEXP (n1, 0) == NULL_RTX || XEXP (n2, 0) == NULL_RTX)
1124 : return false;
1125 1235958 : else if (!(reload_completed
1126 617979 : ? rtx_renumbered_equal_p (XEXP (n1, 0), XEXP (n2, 0))
1127 0 : : rtx_equal_p (XEXP (n1, 0), XEXP (n2, 0))))
1128 : return false;
1129 : }
1130 : }
1131 :
1132 : /* Examine I1 and I2 and return:
1133 : - dir_forward if I1 can be replaced by I2, or
1134 : - dir_backward if I2 can be replaced by I1, or
1135 : - dir_both if both are the case. */
1136 :
1137 : static enum replace_direction
1138 40503134 : old_insns_match_p (int mode ATTRIBUTE_UNUSED, rtx_insn *i1, rtx_insn *i2)
1139 : {
1140 40503134 : rtx p1, p2;
1141 :
1142 : /* Verify that I1 and I2 are equivalent. */
1143 40503134 : if (GET_CODE (i1) != GET_CODE (i2))
1144 : return dir_none;
1145 :
1146 : /* __builtin_unreachable() may lead to empty blocks (ending with
1147 : NOTE_INSN_BASIC_BLOCK). They may be crossjumped. */
1148 34940366 : if (NOTE_INSN_BASIC_BLOCK_P (i1) && NOTE_INSN_BASIC_BLOCK_P (i2))
1149 : return dir_both;
1150 :
1151 : /* ??? Do not allow cross-jumping between different stack levels. */
1152 34862711 : p1 = find_reg_note (i1, REG_ARGS_SIZE, NULL);
1153 34862711 : p2 = find_reg_note (i2, REG_ARGS_SIZE, NULL);
1154 34862711 : if (p1 && p2)
1155 : {
1156 3968596 : p1 = XEXP (p1, 0);
1157 3968596 : p2 = XEXP (p2, 0);
1158 3968596 : if (!rtx_equal_p (p1, p2))
1159 : return dir_none;
1160 :
1161 : /* ??? Worse, this adjustment had better be constant lest we
1162 : have differing incoming stack levels. */
1163 3867697 : if (!frame_pointer_needed
1164 3867697 : && known_eq (find_args_size_adjust (i1), HOST_WIDE_INT_MIN))
1165 22 : return dir_none;
1166 : }
1167 30894115 : else if (p1 || p2)
1168 : return dir_none;
1169 :
1170 : /* Do not allow cross-jumping between frame related insns and other
1171 : insns. */
1172 33212141 : if (RTX_FRAME_RELATED_P (i1) != RTX_FRAME_RELATED_P (i2))
1173 : return dir_none;
1174 :
1175 32612805 : p1 = PATTERN (i1);
1176 32612805 : p2 = PATTERN (i2);
1177 :
1178 32612805 : if (GET_CODE (p1) != GET_CODE (p2))
1179 : return dir_none;
1180 :
1181 : /* If this is a CALL_INSN, compare register usage information.
1182 : If we don't check this on stack register machines, the two
1183 : CALL_INSNs might be merged leaving reg-stack.cc with mismatching
1184 : numbers of stack registers in the same basic block.
1185 : If we don't check this on machines with delay slots, a delay slot may
1186 : be filled that clobbers a parameter expected by the subroutine.
1187 :
1188 : ??? We take the simple route for now and assume that if they're
1189 : equal, they were constructed identically.
1190 :
1191 : Also check for identical exception regions. */
1192 :
1193 30203360 : if (CALL_P (i1))
1194 : {
1195 : /* Ensure the same EH region. */
1196 11975957 : rtx n1 = find_reg_note (i1, REG_EH_REGION, 0);
1197 11975957 : rtx n2 = find_reg_note (i2, REG_EH_REGION, 0);
1198 :
1199 11975957 : if (!n1 && n2)
1200 : return dir_none;
1201 :
1202 11879948 : if (n1 && (!n2 || XEXP (n1, 0) != XEXP (n2, 0)))
1203 : return dir_none;
1204 :
1205 10952922 : if (!rtx_equal_p (CALL_INSN_FUNCTION_USAGE (i1),
1206 10952922 : CALL_INSN_FUNCTION_USAGE (i2))
1207 7324927 : || CALL_INSN_ABI_ID (i1) != CALL_INSN_ABI_ID (i2)
1208 18277849 : || SIBLING_CALL_P (i1) != SIBLING_CALL_P (i2))
1209 : return dir_none;
1210 :
1211 : /* For address sanitizer, never crossjump __asan_report_* builtins,
1212 : otherwise errors might be reported on incorrect lines. */
1213 7324927 : if (flag_sanitize & SANITIZE_ADDRESS)
1214 : {
1215 366909 : rtx call = get_call_rtx_from (i1);
1216 366909 : if (call && GET_CODE (XEXP (XEXP (call, 0), 0)) == SYMBOL_REF)
1217 : {
1218 366909 : rtx symbol = XEXP (XEXP (call, 0), 0);
1219 366909 : if (SYMBOL_REF_DECL (symbol)
1220 366909 : && TREE_CODE (SYMBOL_REF_DECL (symbol)) == FUNCTION_DECL)
1221 : {
1222 366909 : if ((DECL_BUILT_IN_CLASS (SYMBOL_REF_DECL (symbol))
1223 366909 : == BUILT_IN_NORMAL)
1224 364904 : && DECL_FUNCTION_CODE (SYMBOL_REF_DECL (symbol))
1225 : >= BUILT_IN_ASAN_REPORT_LOAD1
1226 730311 : && DECL_FUNCTION_CODE (SYMBOL_REF_DECL (symbol))
1227 : <= BUILT_IN_ASAN_STOREN)
1228 : return dir_none;
1229 : }
1230 : }
1231 : }
1232 :
1233 6962475 : if (insn_callee_abi (i1) != insn_callee_abi (i2))
1234 : return dir_none;
1235 : }
1236 :
1237 : /* If both i1 and i2 are frame related, verify all the CFA notes
1238 : in the same order and with the same content. */
1239 25130886 : if (RTX_FRAME_RELATED_P (i1) && !insns_have_identical_cfa_notes (i1, i2))
1240 : return dir_none;
1241 :
1242 : #ifdef STACK_REGS
1243 : /* If cross_jump_death_matters is not 0, the insn's mode
1244 : indicates whether or not the insn contains any stack-like
1245 : regs. */
1246 :
1247 25009711 : if ((mode & CLEANUP_POST_REGSTACK) && stack_regs_mentioned (i1))
1248 : {
1249 : /* If register stack conversion has already been done, then
1250 : death notes must also be compared before it is certain that
1251 : the two instruction streams match. */
1252 :
1253 : rtx note;
1254 : HARD_REG_SET i1_regset, i2_regset;
1255 :
1256 0 : CLEAR_HARD_REG_SET (i1_regset);
1257 0 : CLEAR_HARD_REG_SET (i2_regset);
1258 :
1259 0 : for (note = REG_NOTES (i1); note; note = XEXP (note, 1))
1260 0 : if (REG_NOTE_KIND (note) == REG_DEAD && STACK_REG_P (XEXP (note, 0)))
1261 0 : SET_HARD_REG_BIT (i1_regset, REGNO (XEXP (note, 0)));
1262 :
1263 0 : for (note = REG_NOTES (i2); note; note = XEXP (note, 1))
1264 0 : if (REG_NOTE_KIND (note) == REG_DEAD && STACK_REG_P (XEXP (note, 0)))
1265 0 : SET_HARD_REG_BIT (i2_regset, REGNO (XEXP (note, 0)));
1266 :
1267 0 : if (i1_regset != i2_regset)
1268 0 : return dir_none;
1269 : }
1270 : #endif
1271 :
1272 25009711 : if (reload_completed
1273 25009711 : ? rtx_renumbered_equal_p (p1, p2) : rtx_equal_p (p1, p2))
1274 : return dir_both;
1275 :
1276 13966723 : return can_replace_by (i1, i2);
1277 : }
1278 :
1279 : /* When comparing insns I1 and I2 in flow_find_cross_jump or
1280 : flow_find_head_matching_sequence, ensure the notes match. */
1281 :
1282 : static void
1283 8742210 : merge_notes (rtx_insn *i1, rtx_insn *i2)
1284 : {
1285 : /* If the merged insns have different REG_EQUAL notes, then
1286 : remove them. */
1287 8742210 : rtx equiv1 = find_reg_equal_equiv_note (i1);
1288 8742210 : rtx equiv2 = find_reg_equal_equiv_note (i2);
1289 :
1290 8742210 : if (equiv1 && !equiv2)
1291 23010 : remove_note (i1, equiv1);
1292 8719200 : else if (!equiv1 && equiv2)
1293 6971 : remove_note (i2, equiv2);
1294 8712229 : else if (equiv1 && equiv2
1295 8712229 : && !rtx_equal_p (XEXP (equiv1, 0), XEXP (equiv2, 0)))
1296 : {
1297 324 : remove_note (i1, equiv1);
1298 324 : remove_note (i2, equiv2);
1299 : }
1300 8742210 : }
1301 :
1302 : /* Walks from I1 in BB1 backward till the next non-debug insn, and returns the
1303 : resulting insn in I1, and the corresponding bb in BB1. At the head of a
1304 : bb, if there is a predecessor bb that reaches this bb via fallthru, and
1305 : FOLLOW_FALLTHRU, walks further in the predecessor bb and registers this in
1306 : DID_FALLTHRU. Otherwise, stops at the head of the bb. */
1307 :
1308 : static void
1309 49110144 : walk_to_nondebug_insn (rtx_insn **i1, basic_block *bb1, bool follow_fallthru,
1310 : bool *did_fallthru)
1311 : {
1312 49110144 : edge fallthru;
1313 :
1314 49110144 : *did_fallthru = false;
1315 :
1316 : /* Ignore notes. */
1317 67352399 : while (!NONDEBUG_INSN_P (*i1))
1318 : {
1319 19406873 : if (*i1 != BB_HEAD (*bb1))
1320 : {
1321 18040635 : *i1 = PREV_INSN (*i1);
1322 18040635 : continue;
1323 : }
1324 :
1325 1366238 : if (!follow_fallthru)
1326 : return;
1327 :
1328 1192233 : fallthru = find_fallthru_edge ((*bb1)->preds);
1329 476683 : if (!fallthru || fallthru->src == ENTRY_BLOCK_PTR_FOR_FN (cfun)
1330 1668859 : || !single_succ_p (fallthru->src))
1331 : return;
1332 :
1333 201620 : *bb1 = fallthru->src;
1334 201620 : *i1 = BB_END (*bb1);
1335 201620 : *did_fallthru = true;
1336 : }
1337 : }
1338 :
1339 : /* Look through the insns at the end of BB1 and BB2 and find the longest
1340 : sequence that are either equivalent, or allow forward or backward
1341 : replacement. Store the first insns for that sequence in *F1 and *F2 and
1342 : return the sequence length.
1343 :
1344 : DIR_P indicates the allowed replacement direction on function entry, and
1345 : the actual replacement direction on function exit. If NULL, only equivalent
1346 : sequences are allowed.
1347 :
1348 : To simplify callers of this function, if the blocks match exactly,
1349 : store the head of the blocks in *F1 and *F2. */
1350 :
1351 : int
1352 16024789 : flow_find_cross_jump (basic_block bb1, basic_block bb2, rtx_insn **f1,
1353 : rtx_insn **f2, enum replace_direction *dir_p)
1354 : {
1355 16024789 : rtx_insn *i1, *i2, *last1, *last2, *afterlast1, *afterlast2;
1356 16024789 : int ninsns = 0;
1357 16024789 : enum replace_direction dir, last_dir, afterlast_dir;
1358 16024789 : bool follow_fallthru, did_fallthru;
1359 :
1360 16024789 : if (dir_p)
1361 16024789 : dir = *dir_p;
1362 : else
1363 : dir = dir_both;
1364 16024789 : afterlast_dir = dir;
1365 16024789 : last_dir = afterlast_dir;
1366 :
1367 : /* Skip simple jumps at the end of the blocks. Complex jumps still
1368 : need to be compared for equivalence, which we'll do below. */
1369 :
1370 16024789 : i1 = BB_END (bb1);
1371 16024789 : last1 = afterlast1 = last2 = afterlast2 = NULL;
1372 16024789 : if (onlyjump_p (i1)
1373 16024789 : || (returnjump_p (i1) && !side_effects_p (PATTERN (i1))))
1374 : {
1375 14397166 : last1 = i1;
1376 14397166 : i1 = PREV_INSN (i1);
1377 : }
1378 :
1379 16024789 : i2 = BB_END (bb2);
1380 16024789 : if (onlyjump_p (i2)
1381 16024789 : || (returnjump_p (i2) && !side_effects_p (PATTERN (i2))))
1382 : {
1383 11697284 : last2 = i2;
1384 : /* Count everything except for unconditional jump as insn.
1385 : Don't count any jumps if dir_p is NULL. */
1386 11697284 : if (!simplejump_p (i2) && !returnjump_p (i2) && last1 && dir_p)
1387 : ninsns++;
1388 11697284 : i2 = PREV_INSN (i2);
1389 : }
1390 :
1391 33085355 : while (true)
1392 : {
1393 : /* In the following example, we can replace all jumps to C by jumps to A.
1394 :
1395 : This removes 4 duplicate insns.
1396 : [bb A] insn1 [bb C] insn1
1397 : insn2 insn2
1398 : [bb B] insn3 insn3
1399 : insn4 insn4
1400 : jump_insn jump_insn
1401 :
1402 : We could also replace all jumps to A by jumps to C, but that leaves B
1403 : alive, and removes only 2 duplicate insns. In a subsequent crossjump
1404 : step, all jumps to B would be replaced with jumps to the middle of C,
1405 : achieving the same result with more effort.
1406 : So we allow only the first possibility, which means that we don't allow
1407 : fallthru in the block that's being replaced. */
1408 :
1409 24555072 : follow_fallthru = dir_p && dir != dir_forward;
1410 24555072 : walk_to_nondebug_insn (&i1, &bb1, follow_fallthru, &did_fallthru);
1411 24555072 : if (did_fallthru)
1412 28537 : dir = dir_backward;
1413 :
1414 24555072 : follow_fallthru = dir_p && dir != dir_backward;
1415 24555072 : walk_to_nondebug_insn (&i2, &bb2, follow_fallthru, &did_fallthru);
1416 24555072 : if (did_fallthru)
1417 173073 : dir = dir_forward;
1418 :
1419 24555072 : if (i1 == BB_HEAD (bb1) || i2 == BB_HEAD (bb2))
1420 : break;
1421 :
1422 : /* Do not turn corssing edge to non-crossing or vice versa after
1423 : reload. */
1424 23773927 : if (BB_PARTITION (BLOCK_FOR_INSN (i1))
1425 23773927 : != BB_PARTITION (BLOCK_FOR_INSN (i2))
1426 23773927 : && reload_completed)
1427 : break;
1428 :
1429 23773927 : dir = merge_dir (dir, old_insns_match_p (0, i1, i2));
1430 21020927 : if (dir == dir_none || (!dir_p && dir != dir_both))
1431 : break;
1432 :
1433 8530283 : merge_memattrs (i1, i2);
1434 :
1435 : /* Don't begin a cross-jump with a NOTE insn. */
1436 8530283 : if (INSN_P (i1))
1437 : {
1438 8530283 : merge_notes (i1, i2);
1439 :
1440 8530283 : afterlast1 = last1, afterlast2 = last2;
1441 8530283 : last1 = i1, last2 = i2;
1442 8530283 : afterlast_dir = last_dir;
1443 8530283 : last_dir = dir;
1444 8530283 : if (active_insn_p (i1))
1445 8420080 : ninsns++;
1446 : }
1447 :
1448 8530283 : i1 = PREV_INSN (i1);
1449 8530283 : i2 = PREV_INSN (i2);
1450 : }
1451 :
1452 : /* Include preceding notes and labels in the cross-jump. One,
1453 : this may bring us to the head of the blocks as requested above.
1454 : Two, it keeps line number notes as matched as may be. */
1455 16024789 : if (ninsns)
1456 : {
1457 5113936 : bb1 = BLOCK_FOR_INSN (last1);
1458 12989915 : while (last1 != BB_HEAD (bb1) && !NONDEBUG_INSN_P (PREV_INSN (last1)))
1459 : last1 = PREV_INSN (last1);
1460 :
1461 9948559 : if (last1 != BB_HEAD (bb1) && LABEL_P (PREV_INSN (last1)))
1462 : last1 = PREV_INSN (last1);
1463 :
1464 5113936 : bb2 = BLOCK_FOR_INSN (last2);
1465 13080988 : while (last2 != BB_HEAD (bb2) && !NONDEBUG_INSN_P (PREV_INSN (last2)))
1466 : last2 = PREV_INSN (last2);
1467 :
1468 9638927 : if (last2 != BB_HEAD (bb2) && LABEL_P (PREV_INSN (last2)))
1469 : last2 = PREV_INSN (last2);
1470 :
1471 5113936 : *f1 = last1;
1472 5113936 : *f2 = last2;
1473 : }
1474 :
1475 16024789 : if (dir_p)
1476 16024789 : *dir_p = last_dir;
1477 16024789 : return ninsns;
1478 : }
1479 :
1480 : /* Like flow_find_cross_jump, except start looking for a matching sequence from
1481 : the head of the two blocks. Do not include jumps at the end.
1482 : If STOP_AFTER is nonzero, stop after finding that many matching
1483 : instructions. If STOP_AFTER is zero, count all INSN_P insns, if it is
1484 : non-zero, only count active insns. */
1485 :
1486 : int
1487 4665431 : flow_find_head_matching_sequence (basic_block bb1, basic_block bb2, rtx_insn **f1,
1488 : rtx_insn **f2, int stop_after)
1489 : {
1490 4665431 : rtx_insn *i1, *i2, *last1, *last2, *beforelast1, *beforelast2;
1491 4665431 : int ninsns = 0;
1492 4665431 : edge e;
1493 4665431 : edge_iterator ei;
1494 4665431 : int nehedges1 = 0, nehedges2 = 0;
1495 :
1496 11139060 : FOR_EACH_EDGE (e, ei, bb1->succs)
1497 6473629 : if (e->flags & EDGE_EH)
1498 363261 : nehedges1++;
1499 11569521 : FOR_EACH_EDGE (e, ei, bb2->succs)
1500 6904090 : if (e->flags & EDGE_EH)
1501 394745 : nehedges2++;
1502 :
1503 4665431 : i1 = BB_HEAD (bb1);
1504 4665431 : i2 = BB_HEAD (bb2);
1505 4665431 : last1 = beforelast1 = last2 = beforelast2 = NULL;
1506 :
1507 198906 : while (true)
1508 : {
1509 : /* Ignore notes, except NOTE_INSN_EPILOGUE_BEG. */
1510 22201471 : while (!NONDEBUG_INSN_P (i1) && i1 != BB_END (bb1))
1511 : {
1512 17156870 : if (NOTE_P (i1) && NOTE_KIND (i1) == NOTE_INSN_EPILOGUE_BEG)
1513 : break;
1514 17138228 : i1 = NEXT_INSN (i1);
1515 : }
1516 :
1517 21955130 : while (!NONDEBUG_INSN_P (i2) && i2 != BB_END (bb2))
1518 : {
1519 17130248 : if (NOTE_P (i2) && NOTE_KIND (i2) == NOTE_INSN_EPILOGUE_BEG)
1520 : break;
1521 17090793 : i2 = NEXT_INSN (i2);
1522 : }
1523 :
1524 4864337 : if ((i1 == BB_END (bb1) && !NONDEBUG_INSN_P (i1))
1525 4851710 : || (i2 == BB_END (bb2) && !NONDEBUG_INSN_P (i2)))
1526 : break;
1527 :
1528 4847010 : if (NOTE_P (i1) || NOTE_P (i2)
1529 4790962 : || JUMP_P (i1) || JUMP_P (i2))
1530 : break;
1531 :
1532 : /* A sanity check to make sure we're not merging insns with different
1533 : effects on EH. If only one of them ends a basic block, it shouldn't
1534 : have an EH edge; if both end a basic block, there should be the same
1535 : number of EH edges. */
1536 3898916 : if ((i1 == BB_END (bb1) && i2 != BB_END (bb2)
1537 219823 : && nehedges1 > 0)
1538 3860043 : || (i2 == BB_END (bb2) && i1 != BB_END (bb1)
1539 238996 : && nehedges2 > 0)
1540 3832293 : || (i1 == BB_END (bb1) && i2 == BB_END (bb2)
1541 26744 : && nehedges1 != nehedges2))
1542 : break;
1543 :
1544 3828901 : if (old_insns_match_p (0, i1, i2) != dir_both)
1545 : break;
1546 :
1547 211927 : merge_memattrs (i1, i2);
1548 :
1549 : /* Don't begin a cross-jump with a NOTE insn. */
1550 211927 : if (INSN_P (i1))
1551 : {
1552 211927 : merge_notes (i1, i2);
1553 :
1554 211927 : beforelast1 = last1, beforelast2 = last2;
1555 211927 : last1 = i1, last2 = i2;
1556 211927 : if (!stop_after || active_insn_p (i1))
1557 211927 : ninsns++;
1558 : }
1559 :
1560 211927 : if (i1 == BB_END (bb1) || i2 == BB_END (bb2)
1561 198906 : || (stop_after > 0 && ninsns == stop_after))
1562 : break;
1563 :
1564 198906 : i1 = NEXT_INSN (i1);
1565 198906 : i2 = NEXT_INSN (i2);
1566 : }
1567 :
1568 4665431 : if (ninsns)
1569 : {
1570 119181 : *f1 = last1;
1571 119181 : *f2 = last2;
1572 : }
1573 :
1574 4665431 : return ninsns;
1575 : }
1576 :
1577 : /* Return true iff outgoing edges of BB1 and BB2 match, together with
1578 : the branch instruction. This means that if we commonize the control
1579 : flow before end of the basic block, the semantic remains unchanged.
1580 :
1581 : We may assume that there exists one edge with a common destination. */
1582 :
1583 : static bool
1584 47144490 : outgoing_edges_match (int mode, basic_block bb1, basic_block bb2)
1585 : {
1586 47144490 : int nehedges1 = 0, nehedges2 = 0;
1587 47144490 : edge fallthru1 = 0, fallthru2 = 0;
1588 47144490 : edge e1, e2;
1589 47144490 : edge_iterator ei;
1590 :
1591 : /* If we performed shrink-wrapping, edges to the exit block can
1592 : only be distinguished for JUMP_INSNs. The two paths may differ in
1593 : whether they went through the prologue. Sibcalls are fine, we know
1594 : that we either didn't need or inserted an epilogue before them. */
1595 47144490 : if (crtl->shrink_wrapped
1596 1233610 : && single_succ_p (bb1)
1597 481987 : && single_succ (bb1) == EXIT_BLOCK_PTR_FOR_FN (cfun)
1598 155359 : && (!JUMP_P (BB_END (bb1))
1599 : /* Punt if the only successor is a fake edge to exit, the jump
1600 : must be some weird one. */
1601 65657 : || (single_succ_edge (bb1)->flags & EDGE_FAKE) != 0)
1602 47234272 : && !(CALL_P (BB_END (bb1)) && SIBLING_CALL_P (BB_END (bb1))))
1603 : return false;
1604 :
1605 : /* If BB1 has only one successor, we may be looking at either an
1606 : unconditional jump, or a fake edge to exit. */
1607 47090971 : if (single_succ_p (bb1)
1608 19010210 : && (single_succ_edge (bb1)->flags & (EDGE_COMPLEX | EDGE_FAKE)) == 0
1609 62558661 : && (!JUMP_P (BB_END (bb1)) || simplejump_p (BB_END (bb1))))
1610 15199415 : return (single_succ_p (bb2)
1611 14005484 : && (single_succ_edge (bb2)->flags
1612 14005484 : & (EDGE_COMPLEX | EDGE_FAKE)) == 0
1613 29146425 : && (!JUMP_P (BB_END (bb2)) || simplejump_p (BB_END (bb2))));
1614 :
1615 : /* Match conditional jumps - this may get tricky when fallthru and branch
1616 : edges are crossed. */
1617 31891556 : if (EDGE_COUNT (bb1->succs) == 2
1618 28002415 : && any_condjump_p (BB_END (bb1))
1619 50881546 : && onlyjump_p (BB_END (bb1)))
1620 : {
1621 18989990 : edge b1, f1, b2, f2;
1622 18989990 : bool reverse, match;
1623 18989990 : rtx set1, set2, cond1, cond2;
1624 18989990 : enum rtx_code code1, code2;
1625 :
1626 18989990 : if (EDGE_COUNT (bb2->succs) != 2
1627 8640839 : || !any_condjump_p (BB_END (bb2))
1628 27596098 : || !onlyjump_p (BB_END (bb2)))
1629 10383882 : return false;
1630 :
1631 8606108 : b1 = BRANCH_EDGE (bb1);
1632 8606108 : b2 = BRANCH_EDGE (bb2);
1633 8606108 : f1 = FALLTHRU_EDGE (bb1);
1634 8606108 : f2 = FALLTHRU_EDGE (bb2);
1635 :
1636 : /* Get around possible forwarders on fallthru edges. Other cases
1637 : should be optimized out already. */
1638 8606108 : if (FORWARDER_BLOCK_P (f1->dest))
1639 3317098 : f1 = single_succ_edge (f1->dest);
1640 :
1641 8606108 : if (FORWARDER_BLOCK_P (f2->dest))
1642 2514090 : f2 = single_succ_edge (f2->dest);
1643 :
1644 : /* To simplify use of this function, return false if there are
1645 : unneeded forwarder blocks. These will get eliminated later
1646 : during cleanup_cfg. */
1647 8606108 : if (FORWARDER_BLOCK_P (f1->dest)
1648 8600781 : || FORWARDER_BLOCK_P (f2->dest)
1649 8594961 : || FORWARDER_BLOCK_P (b1->dest)
1650 8570078 : || FORWARDER_BLOCK_P (b2->dest))
1651 : return false;
1652 :
1653 8544228 : if (f1->dest == f2->dest && b1->dest == b2->dest)
1654 : reverse = false;
1655 8346905 : else if (f1->dest == b2->dest && b1->dest == f2->dest)
1656 : reverse = true;
1657 : else
1658 : return false;
1659 :
1660 328974 : set1 = pc_set (BB_END (bb1));
1661 328974 : set2 = pc_set (BB_END (bb2));
1662 328974 : if ((XEXP (SET_SRC (set1), 1) == pc_rtx)
1663 328974 : != (XEXP (SET_SRC (set2), 1) == pc_rtx))
1664 0 : reverse = !reverse;
1665 :
1666 328974 : cond1 = XEXP (SET_SRC (set1), 0);
1667 328974 : cond2 = XEXP (SET_SRC (set2), 0);
1668 328974 : code1 = GET_CODE (cond1);
1669 328974 : if (reverse)
1670 131651 : code2 = reversed_comparison_code (cond2, BB_END (bb2));
1671 : else
1672 197323 : code2 = GET_CODE (cond2);
1673 :
1674 328974 : if (code2 == UNKNOWN)
1675 : return false;
1676 :
1677 : /* Verify codes and operands match. */
1678 935630 : match = ((code1 == code2
1679 284718 : && rtx_renumbered_equal_p (XEXP (cond1, 0), XEXP (cond2, 0))
1680 282485 : && rtx_renumbered_equal_p (XEXP (cond1, 1), XEXP (cond2, 1)))
1681 331207 : || (code1 == swap_condition (code2)
1682 3630 : && rtx_renumbered_equal_p (XEXP (cond1, 1),
1683 3630 : XEXP (cond2, 0))
1684 0 : && rtx_renumbered_equal_p (XEXP (cond1, 0),
1685 0 : XEXP (cond2, 1))));
1686 :
1687 : /* If we return true, we will join the blocks. Which means that
1688 : we will only have one branch prediction bit to work with. Thus
1689 : we require the existing branches to have probabilities that are
1690 : roughly similar. */
1691 282485 : if (match
1692 282485 : && optimize_bb_for_speed_p (bb1)
1693 255324 : && optimize_bb_for_speed_p (bb2))
1694 : {
1695 245916 : profile_probability prob2;
1696 :
1697 245916 : if (b1->dest == b2->dest)
1698 149416 : prob2 = b2->probability;
1699 : else
1700 : /* Do not use f2 probability as f2 may be forwarded. */
1701 96500 : prob2 = b2->probability.invert ();
1702 :
1703 : /* Fail if the difference in probabilities is greater than 50%.
1704 : This rules out two well-predicted branches with opposite
1705 : outcomes. */
1706 245916 : if (b1->probability.differs_lot_from_p (prob2))
1707 : {
1708 4803 : if (dump_file)
1709 : {
1710 0 : fprintf (dump_file,
1711 : "Outcomes of branch in bb %i and %i differ too"
1712 : " much (", bb1->index, bb2->index);
1713 0 : b1->probability.dump (dump_file);
1714 0 : prob2.dump (dump_file);
1715 0 : fprintf (dump_file, ")\n");
1716 : }
1717 4803 : return false;
1718 : }
1719 : }
1720 :
1721 324171 : if (dump_file && match)
1722 16 : fprintf (dump_file, "Conditionals in bb %i and %i match.\n",
1723 : bb1->index, bb2->index);
1724 :
1725 324171 : return match;
1726 : }
1727 :
1728 : /* Generic case - we are seeing a computed jump, table jump or trapping
1729 : instruction. */
1730 :
1731 : /* Check whether there are tablejumps in the end of BB1 and BB2.
1732 : Return true if they are identical. */
1733 12901566 : {
1734 12901566 : rtx_insn *label1, *label2;
1735 12901566 : rtx_jump_table_data *table1, *table2;
1736 :
1737 12901566 : if (tablejump_p (BB_END (bb1), &label1, &table1)
1738 75790 : && tablejump_p (BB_END (bb2), &label2, &table2)
1739 12902998 : && GET_CODE (PATTERN (table1)) == GET_CODE (PATTERN (table2)))
1740 : {
1741 : /* The labels should never be the same rtx. If they really are same
1742 : the jump tables are same too. So disable crossjumping of blocks BB1
1743 : and BB2 because when deleting the common insns in the end of BB1
1744 : by delete_basic_block () the jump table would be deleted too. */
1745 : /* If LABEL2 is referenced in BB1->END do not do anything
1746 : because we would loose information when replacing
1747 : LABEL1 by LABEL2 and then LABEL2 by LABEL1 in BB1->END. */
1748 1432 : if (label1 != label2 && !rtx_referenced_p (label2, BB_END (bb1)))
1749 : {
1750 : /* Set IDENTICAL to true when the tables are identical. */
1751 1432 : bool identical = false;
1752 1432 : rtx p1, p2;
1753 :
1754 1432 : p1 = PATTERN (table1);
1755 1432 : p2 = PATTERN (table2);
1756 1432 : if (GET_CODE (p1) == ADDR_VEC && rtx_equal_p (p1, p2))
1757 : {
1758 : identical = true;
1759 : }
1760 1308 : else if (GET_CODE (p1) == ADDR_DIFF_VEC
1761 364 : && (XVECLEN (p1, 1) == XVECLEN (p2, 1))
1762 258 : && rtx_equal_p (XEXP (p1, 2), XEXP (p2, 2))
1763 1566 : && rtx_equal_p (XEXP (p1, 3), XEXP (p2, 3)))
1764 : {
1765 258 : int i;
1766 :
1767 258 : identical = true;
1768 1152 : for (i = XVECLEN (p1, 1) - 1; i >= 0 && identical; i--)
1769 894 : if (!rtx_equal_p (XVECEXP (p1, 1, i), XVECEXP (p2, 1, i)))
1770 : identical = false;
1771 : }
1772 :
1773 258 : if (identical)
1774 : {
1775 172 : bool match;
1776 :
1777 : /* Temporarily replace references to LABEL1 with LABEL2
1778 : in BB1->END so that we could compare the instructions. */
1779 172 : replace_label_in_insn (BB_END (bb1), label1, label2, false);
1780 :
1781 172 : match = (old_insns_match_p (mode, BB_END (bb1), BB_END (bb2))
1782 : == dir_both);
1783 172 : if (dump_file && match)
1784 0 : fprintf (dump_file,
1785 : "Tablejumps in bb %i and %i match.\n",
1786 : bb1->index, bb2->index);
1787 :
1788 : /* Set the original label in BB1->END because when deleting
1789 : a block whose end is a tablejump, the tablejump referenced
1790 : from the instruction is deleted too. */
1791 172 : replace_label_in_insn (BB_END (bb1), label2, label1, false);
1792 :
1793 1432 : return match;
1794 : }
1795 : }
1796 1260 : return false;
1797 : }
1798 : }
1799 :
1800 : /* Find the last non-debug non-note instruction in each bb, except
1801 : stop when we see the NOTE_INSN_BASIC_BLOCK, as old_insns_match_p
1802 : handles that case specially. old_insns_match_p does not handle
1803 : other types of instruction notes. */
1804 12900134 : rtx_insn *last1 = BB_END (bb1);
1805 12900134 : rtx_insn *last2 = BB_END (bb2);
1806 12900225 : while (!NOTE_INSN_BASIC_BLOCK_P (last1) &&
1807 12782616 : (DEBUG_INSN_P (last1) || NOTE_P (last1)))
1808 91 : last1 = PREV_INSN (last1);
1809 12929480 : while (!NOTE_INSN_BASIC_BLOCK_P (last2) &&
1810 12815160 : (DEBUG_INSN_P (last2) || NOTE_P (last2)))
1811 29346 : last2 = PREV_INSN (last2);
1812 12900134 : gcc_assert (last1 && last2);
1813 :
1814 : /* First ensure that the instructions match. There may be many outgoing
1815 : edges so this test is generally cheaper. */
1816 12900134 : if (old_insns_match_p (mode, last1, last2) != dir_both)
1817 : return false;
1818 :
1819 : /* Search the outgoing edges, ensure that the counts do match, find possible
1820 : fallthru and exception handling edges since these needs more
1821 : validation. */
1822 7134816 : if (EDGE_COUNT (bb1->succs) != EDGE_COUNT (bb2->succs))
1823 : return false;
1824 :
1825 2378259 : bool nonfakeedges = false;
1826 5831956 : FOR_EACH_EDGE (e1, ei, bb1->succs)
1827 : {
1828 3453697 : e2 = EDGE_SUCC (bb2, ei.index);
1829 :
1830 3453697 : if ((e1->flags & EDGE_FAKE) == 0)
1831 2497234 : nonfakeedges = true;
1832 :
1833 3453697 : if (e1->flags & EDGE_EH)
1834 1120375 : nehedges1++;
1835 :
1836 3453697 : if (e2->flags & EDGE_EH)
1837 1120375 : nehedges2++;
1838 :
1839 3453697 : if (e1->flags & EDGE_FALLTHRU)
1840 1159967 : fallthru1 = e1;
1841 3453697 : if (e2->flags & EDGE_FALLTHRU)
1842 1159967 : fallthru2 = e2;
1843 : }
1844 :
1845 : /* If number of edges of various types does not match, fail. */
1846 2378259 : if (nehedges1 != nehedges2
1847 2378259 : || (fallthru1 != 0) != (fallthru2 != 0))
1848 : return false;
1849 :
1850 : /* If !ACCUMULATE_OUTGOING_ARGS, bb1 (and bb2) have no successors
1851 : and the last real insn doesn't have REG_ARGS_SIZE note, don't
1852 : attempt to optimize, as the two basic blocks might have different
1853 : REG_ARGS_SIZE depths. For noreturn calls and unconditional
1854 : traps there should be REG_ARG_SIZE notes, they could be missing
1855 : for __builtin_unreachable () uses though. */
1856 2378259 : if (!nonfakeedges
1857 956463 : && !ACCUMULATE_OUTGOING_ARGS
1858 3334715 : && (!INSN_P (last1)
1859 956456 : || !find_reg_note (last1, REG_ARGS_SIZE, NULL)))
1860 11 : return false;
1861 :
1862 : /* fallthru edges must be forwarded to the same destination. */
1863 2378248 : if (fallthru1)
1864 : {
1865 1159967 : basic_block d1 = (FORWARDER_BLOCK_P (fallthru1->dest)
1866 1159967 : ? single_succ (fallthru1->dest) : fallthru1->dest);
1867 1159967 : basic_block d2 = (FORWARDER_BLOCK_P (fallthru2->dest)
1868 1159967 : ? single_succ (fallthru2->dest) : fallthru2->dest);
1869 :
1870 1159967 : if (d1 != d2)
1871 : return false;
1872 : }
1873 :
1874 : /* Ensure the same EH region. */
1875 1799967 : {
1876 1799967 : rtx n1 = find_reg_note (last1, REG_EH_REGION, 0);
1877 1799967 : rtx n2 = find_reg_note (last2, REG_EH_REGION, 0);
1878 :
1879 1799967 : if (!n1 && n2)
1880 : return false;
1881 :
1882 1799967 : if (n1 && (!n2 || XEXP (n1, 0) != XEXP (n2, 0)))
1883 : return false;
1884 : }
1885 :
1886 : /* The same checks as in try_crossjump_to_edge. It is required for RTL
1887 : version of sequence abstraction. */
1888 4096449 : FOR_EACH_EDGE (e1, ei, bb2->succs)
1889 : {
1890 2296512 : edge e2;
1891 2296512 : edge_iterator ei;
1892 2296512 : basic_block d1 = e1->dest;
1893 :
1894 2296512 : if (FORWARDER_BLOCK_P (d1))
1895 604990 : d1 = EDGE_SUCC (d1, 0)->dest;
1896 :
1897 2794527 : FOR_EACH_EDGE (e2, ei, bb1->succs)
1898 : {
1899 2794527 : basic_block d2 = e2->dest;
1900 2794527 : if (FORWARDER_BLOCK_P (d2))
1901 782272 : d2 = EDGE_SUCC (d2, 0)->dest;
1902 2794527 : if (d1 == d2)
1903 : break;
1904 : }
1905 :
1906 2296512 : if (!e2)
1907 0 : return false;
1908 : }
1909 :
1910 : return true;
1911 : }
1912 :
1913 : /* Returns true if BB basic block has a preserve label. */
1914 :
1915 : static bool
1916 367555 : block_has_preserve_label (basic_block bb)
1917 : {
1918 367555 : return (bb
1919 367555 : && block_label (bb)
1920 682550 : && LABEL_PRESERVE_P (block_label (bb)));
1921 : }
1922 :
1923 : /* E1 and E2 are edges with the same destination block. Search their
1924 : predecessors for common code. If found, redirect control flow from
1925 : (maybe the middle of) E1->SRC to (maybe the middle of) E2->SRC (dir_forward),
1926 : or the other way around (dir_backward). DIR specifies the allowed
1927 : replacement direction. */
1928 :
1929 : static bool
1930 52066898 : try_crossjump_to_edge (int mode, edge e1, edge e2,
1931 : enum replace_direction dir)
1932 : {
1933 52066898 : int nmatch;
1934 52066898 : basic_block src1 = e1->src, src2 = e2->src;
1935 52066898 : basic_block redirect_to, redirect_from, to_remove;
1936 52066898 : basic_block osrc1, osrc2, redirect_edges_to, tmp;
1937 52066898 : rtx_insn *newpos1, *newpos2;
1938 52066898 : edge s;
1939 52066898 : edge_iterator ei;
1940 :
1941 52066898 : newpos1 = newpos2 = NULL;
1942 :
1943 : /* Search backward through forwarder blocks. We don't need to worry
1944 : about multiple entry or chained forwarders, as they will be optimized
1945 : away. We do this to look past the unconditional jump following a
1946 : conditional jump that is required due to the current CFG shape. */
1947 52066898 : if (single_pred_p (src1)
1948 52066898 : && FORWARDER_BLOCK_P (src1))
1949 11896426 : e1 = single_pred_edge (src1), src1 = e1->src;
1950 :
1951 52066898 : if (single_pred_p (src2)
1952 52066687 : && FORWARDER_BLOCK_P (src2))
1953 5740764 : e2 = single_pred_edge (src2), src2 = e2->src;
1954 :
1955 : /* Nothing to do if we reach ENTRY, or a common source block. */
1956 52066898 : if (src1 == ENTRY_BLOCK_PTR_FOR_FN (cfun) || src2
1957 : == ENTRY_BLOCK_PTR_FOR_FN (cfun))
1958 : return false;
1959 52066466 : if (src1 == src2)
1960 : return false;
1961 :
1962 : /* Seeing more than 1 forwarder blocks would confuse us later... */
1963 52066338 : if (FORWARDER_BLOCK_P (e1->dest)
1964 52066338 : && FORWARDER_BLOCK_P (single_succ (e1->dest)))
1965 : return false;
1966 :
1967 52054579 : if (FORWARDER_BLOCK_P (e2->dest)
1968 52054579 : && FORWARDER_BLOCK_P (single_succ (e2->dest)))
1969 : return false;
1970 :
1971 : /* Likewise with dead code (possibly newly created by the other optimizations
1972 : of cfg_cleanup). */
1973 52053953 : if (EDGE_COUNT (src1->preds) == 0 || EDGE_COUNT (src2->preds) == 0)
1974 : return false;
1975 :
1976 : /* Do not turn corssing edge to non-crossing or vice versa after reload. */
1977 47331482 : if (BB_PARTITION (src1) != BB_PARTITION (src2)
1978 186992 : && reload_completed)
1979 : return false;
1980 :
1981 : /* Look for the common insn sequence, part the first ... */
1982 47144490 : if (!outgoing_edges_match (mode, src1, src2))
1983 : return false;
1984 :
1985 : /* ... and part the second. */
1986 16024789 : nmatch = flow_find_cross_jump (src1, src2, &newpos1, &newpos2, &dir);
1987 :
1988 16024789 : osrc1 = src1;
1989 16024789 : osrc2 = src2;
1990 16024789 : if (newpos1 != NULL_RTX)
1991 5113936 : src1 = BLOCK_FOR_INSN (newpos1);
1992 16024789 : if (newpos2 != NULL_RTX)
1993 5113936 : src2 = BLOCK_FOR_INSN (newpos2);
1994 :
1995 : /* Check that SRC1 and SRC2 have preds again. They may have changed
1996 : above due to the call to flow_find_cross_jump. */
1997 67763779 : if (EDGE_COUNT (src1->preds) == 0 || EDGE_COUNT (src2->preds) == 0)
1998 : return false;
1999 :
2000 16024789 : if (dir == dir_backward)
2001 : {
2002 1853 : std::swap (osrc1, osrc2);
2003 1853 : std::swap (src1, src2);
2004 1853 : std::swap (e1, e2);
2005 1853 : std::swap (newpos1, newpos2);
2006 : }
2007 :
2008 : /* Don't proceed with the crossjump unless we found a sufficient number
2009 : of matching instructions or the 'from' block was totally matched
2010 : (such that its predecessors will hopefully be redirected and the
2011 : block removed). */
2012 16024789 : if ((nmatch < param_min_crossjump_insns)
2013 15898154 : && (newpos1 != BB_HEAD (src1)))
2014 : return false;
2015 :
2016 : /* Avoid deleting preserve label when redirecting ABNORMAL edges. */
2017 367555 : if (block_has_preserve_label (e1->dest)
2018 367555 : && (e1->flags & EDGE_ABNORMAL))
2019 : return false;
2020 :
2021 : /* Here we know that the insns in the end of SRC1 which are common with SRC2
2022 : will be deleted.
2023 : If we have tablejumps in the end of SRC1 and SRC2
2024 : they have been already compared for equivalence in outgoing_edges_match ()
2025 : so replace the references to TABLE1 by references to TABLE2. */
2026 327908 : {
2027 327908 : rtx_insn *label1, *label2;
2028 327908 : rtx_jump_table_data *table1, *table2;
2029 :
2030 327908 : if (tablejump_p (BB_END (osrc1), &label1, &table1)
2031 124 : && tablejump_p (BB_END (osrc2), &label2, &table2)
2032 328032 : && label1 != label2)
2033 : {
2034 124 : rtx_insn *insn;
2035 :
2036 : /* Replace references to LABEL1 with LABEL2. */
2037 387514 : for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
2038 : {
2039 : /* Do not replace the label in SRC1->END because when deleting
2040 : a block whose end is a tablejump, the tablejump referenced
2041 : from the instruction is deleted too. */
2042 387390 : if (insn != BB_END (osrc1))
2043 387266 : replace_label_in_insn (insn, label1, label2, true);
2044 : }
2045 : }
2046 : }
2047 :
2048 : /* Avoid splitting if possible. We must always split when SRC2 has
2049 : EH predecessor edges, or we may end up with basic blocks with both
2050 : normal and EH predecessor edges. */
2051 327908 : if (newpos2 == BB_HEAD (src2)
2052 327908 : && !(EDGE_PRED (src2, 0)->flags & EDGE_EH))
2053 : redirect_to = src2;
2054 : else
2055 : {
2056 78296 : if (newpos2 == BB_HEAD (src2))
2057 : {
2058 : /* Skip possible basic block header. */
2059 5814 : if (LABEL_P (newpos2))
2060 5814 : newpos2 = NEXT_INSN (newpos2);
2061 5814 : while (DEBUG_INSN_P (newpos2))
2062 0 : newpos2 = NEXT_INSN (newpos2);
2063 5814 : if (NOTE_P (newpos2))
2064 5814 : newpos2 = NEXT_INSN (newpos2);
2065 6009 : while (DEBUG_INSN_P (newpos2))
2066 195 : newpos2 = NEXT_INSN (newpos2);
2067 : }
2068 :
2069 78296 : if (dump_file)
2070 0 : fprintf (dump_file, "Splitting bb %i before %i insns\n",
2071 : src2->index, nmatch);
2072 78296 : redirect_to = split_block (src2, PREV_INSN (newpos2))->dest;
2073 : }
2074 :
2075 327908 : if (dump_file)
2076 4 : fprintf (dump_file,
2077 : "Cross jumping from bb %i to bb %i; %i common insns\n",
2078 : src1->index, src2->index, nmatch);
2079 :
2080 : /* We may have some registers visible through the block. */
2081 327908 : df_set_bb_dirty (redirect_to);
2082 :
2083 327908 : if (osrc2 == src2)
2084 : redirect_edges_to = redirect_to;
2085 : else
2086 10903 : redirect_edges_to = osrc2;
2087 :
2088 : /* Recompute the counts of destinations of outgoing edges. */
2089 725094 : FOR_EACH_EDGE (s, ei, redirect_edges_to->succs)
2090 : {
2091 397186 : edge s2;
2092 397186 : edge_iterator ei;
2093 397186 : basic_block d = s->dest;
2094 :
2095 397186 : if (FORWARDER_BLOCK_P (d))
2096 29763 : d = single_succ (d);
2097 :
2098 472098 : FOR_EACH_EDGE (s2, ei, src1->succs)
2099 : {
2100 472098 : basic_block d2 = s2->dest;
2101 472098 : if (FORWARDER_BLOCK_P (d2))
2102 100554 : d2 = single_succ (d2);
2103 472098 : if (d == d2)
2104 : break;
2105 : }
2106 :
2107 : /* Take care to update possible forwarder blocks. We verified
2108 : that there is no more than one in the chain, so we can't run
2109 : into infinite loop. */
2110 397186 : if (FORWARDER_BLOCK_P (s->dest))
2111 29763 : s->dest->count += s->count ();
2112 :
2113 397186 : if (FORWARDER_BLOCK_P (s2->dest))
2114 77324 : s2->dest->count -= s->count ();
2115 :
2116 397186 : s->probability = s->probability.combine_with_count
2117 397186 : (redirect_edges_to->count,
2118 : s2->probability, src1->count);
2119 : }
2120 :
2121 : /* Adjust count for the block. An earlier jump
2122 : threading pass may have left the profile in an inconsistent
2123 : state (see update_bb_profile_for_threading) so we must be
2124 : prepared for overflows. */
2125 : tmp = redirect_to;
2126 350964 : do
2127 : {
2128 339436 : tmp->count += src1->count;
2129 339436 : if (tmp == redirect_edges_to)
2130 : break;
2131 11528 : tmp = find_fallthru_edge (tmp->succs)->dest;
2132 : }
2133 : while (true);
2134 327908 : update_br_prob_note (redirect_edges_to);
2135 :
2136 : /* Edit SRC1 to go to REDIRECT_TO at NEWPOS1. */
2137 :
2138 : /* Skip possible basic block header. */
2139 327908 : if (LABEL_P (newpos1))
2140 129648 : newpos1 = NEXT_INSN (newpos1);
2141 :
2142 344262 : while (DEBUG_INSN_P (newpos1))
2143 16354 : newpos1 = NEXT_INSN (newpos1);
2144 :
2145 327908 : if (NOTE_INSN_BASIC_BLOCK_P (newpos1))
2146 243273 : newpos1 = NEXT_INSN (newpos1);
2147 :
2148 : /* Skip also prologue and function markers. */
2149 837751 : while (DEBUG_INSN_P (newpos1)
2150 837751 : || (NOTE_P (newpos1)
2151 13938 : && (NOTE_KIND (newpos1) == NOTE_INSN_PROLOGUE_END
2152 13938 : || NOTE_KIND (newpos1) == NOTE_INSN_FUNCTION_BEG)))
2153 509843 : newpos1 = NEXT_INSN (newpos1);
2154 :
2155 327908 : redirect_from = split_block (src1, PREV_INSN (newpos1))->src;
2156 327908 : to_remove = single_succ (redirect_from);
2157 :
2158 327908 : redirect_edge_and_branch_force (single_succ_edge (redirect_from), redirect_to);
2159 327908 : delete_basic_block (to_remove);
2160 :
2161 327908 : update_forwarder_flag (redirect_from);
2162 327908 : if (redirect_to != src2)
2163 78296 : update_forwarder_flag (src2);
2164 :
2165 : return true;
2166 : }
2167 :
2168 : /* Search the predecessors of BB for common insn sequences. When found,
2169 : share code between them by redirecting control flow. Return true if
2170 : any changes made. */
2171 :
2172 : static bool
2173 30993471 : try_crossjump_bb (int mode, basic_block bb)
2174 : {
2175 30993471 : edge e, e2, fallthru;
2176 30993471 : bool changed;
2177 30993471 : unsigned max, ix, ix2;
2178 :
2179 : /* Nothing to do if there is not at least two incoming edges. */
2180 31217151 : if (EDGE_COUNT (bb->preds) < 2)
2181 : return false;
2182 :
2183 : /* Don't crossjump if this block ends in a computed jump,
2184 : unless we are optimizing for size. */
2185 8499848 : if (optimize_bb_for_size_p (bb)
2186 1360566 : && bb != EXIT_BLOCK_PTR_FOR_FN (cfun)
2187 9820114 : && computed_jump_p (BB_END (bb)))
2188 : return false;
2189 :
2190 : /* If we are partitioning hot/cold basic blocks, we don't want to
2191 : mess up unconditional or indirect jumps that cross between hot
2192 : and cold sections.
2193 :
2194 : Basic block partitioning may result in some jumps that appear to
2195 : be optimizable (or blocks that appear to be mergeable), but which really
2196 : must be left untouched (they are required to make it safely across
2197 : partition boundaries). See the comments at the top of
2198 : bb-reorder.cc:partition_hot_cold_basic_blocks for complete details. */
2199 :
2200 8499818 : if (BB_PARTITION (EDGE_PRED (bb, 0)->src) !=
2201 8499818 : BB_PARTITION (EDGE_PRED (bb, 1)->src)
2202 8499818 : || (EDGE_PRED (bb, 0)->flags & EDGE_CROSSING))
2203 : return false;
2204 :
2205 : /* It is always cheapest to redirect a block that ends in a branch to
2206 : a block that falls through into BB, as that adds no branches to the
2207 : program. We'll try that combination first. */
2208 8279030 : fallthru = NULL;
2209 8279030 : max = param_max_crossjump_edges;
2210 :
2211 8279030 : if (EDGE_COUNT (bb->preds) > max)
2212 : return false;
2213 :
2214 8276168 : fallthru = find_fallthru_edge (bb->preds);
2215 :
2216 8276168 : changed = false;
2217 40627866 : for (ix = 0; ix < EDGE_COUNT (bb->preds);)
2218 : {
2219 24075530 : e = EDGE_PRED (bb, ix);
2220 24075530 : ix++;
2221 :
2222 : /* As noted above, first try with the fallthru predecessor (or, a
2223 : fallthru predecessor if we are in cfglayout mode). */
2224 24075530 : if (fallthru)
2225 : {
2226 : /* Don't combine the fallthru edge into anything else.
2227 : If there is a match, we'll do it the other way around. */
2228 17638413 : if (e == fallthru)
2229 6662513 : continue;
2230 : /* If nothing changed since the last attempt, there is nothing
2231 : we can do. */
2232 10975900 : if (!first_pass
2233 4401388 : && !((e->src->flags & BB_MODIFIED)
2234 3530123 : || (fallthru->src->flags & BB_MODIFIED)))
2235 3150371 : continue;
2236 :
2237 7825529 : if (try_crossjump_to_edge (mode, e, fallthru, dir_forward))
2238 : {
2239 141358 : changed = true;
2240 141358 : ix = 0;
2241 141358 : continue;
2242 : }
2243 : }
2244 :
2245 : /* Non-obvious work limiting check: Recognize that we're going
2246 : to call try_crossjump_bb on every basic block. So if we have
2247 : two blocks with lots of outgoing edges (a switch) and they
2248 : share lots of common destinations, then we would do the
2249 : cross-jump check once for each common destination.
2250 :
2251 : Now, if the blocks actually are cross-jump candidates, then
2252 : all of their destinations will be shared. Which means that
2253 : we only need check them for cross-jump candidacy once. We
2254 : can eliminate redundant checks of crossjump(A,B) by arbitrarily
2255 : choosing to do the check from the block for which the edge
2256 : in question is the first successor of A. */
2257 14121288 : if (EDGE_SUCC (e->src, 0) != e)
2258 2861001 : continue;
2259 :
2260 171266145 : for (ix2 = 0; ix2 < EDGE_COUNT (bb->preds); ix2++)
2261 : {
2262 127840710 : e2 = EDGE_PRED (bb, ix2);
2263 :
2264 127840710 : if (e2 == e)
2265 11172028 : continue;
2266 :
2267 : /* We've already checked the fallthru edge above. */
2268 116668682 : if (e2 == fallthru)
2269 6156218 : continue;
2270 :
2271 : /* The "first successor" check above only prevents multiple
2272 : checks of crossjump(A,B). In order to prevent redundant
2273 : checks of crossjump(B,A), require that A be the block
2274 : with the lowest index. */
2275 110512464 : if (e->src->index > e2->src->index)
2276 55325662 : continue;
2277 :
2278 : /* If nothing changed since the last attempt, there is nothing
2279 : we can do. */
2280 55186802 : if (!first_pass
2281 14248316 : && !((e->src->flags & BB_MODIFIED)
2282 11814948 : || (e2->src->flags & BB_MODIFIED)))
2283 10945433 : continue;
2284 :
2285 : /* Both e and e2 are not fallthru edges, so we can crossjump in either
2286 : direction. */
2287 44241369 : if (try_crossjump_to_edge (mode, e, e2, dir_both))
2288 : {
2289 : changed = true;
2290 : ix = 0;
2291 : break;
2292 : }
2293 : }
2294 : }
2295 :
2296 8276168 : if (changed)
2297 155535 : crossjumps_occurred = true;
2298 :
2299 : return changed;
2300 : }
2301 :
2302 : /* Search the successors of BB for common insn sequences. When found,
2303 : share code between them by moving it across the basic block
2304 : boundary. Return true if any changes made. */
2305 :
2306 : static bool
2307 29785841 : try_head_merge_bb (basic_block bb)
2308 : {
2309 29785841 : basic_block final_dest_bb = NULL;
2310 29785841 : int max_match = INT_MAX;
2311 29785841 : edge e0;
2312 29785841 : rtx_insn **headptr, **currptr, **nextptr;
2313 29785841 : bool changed, moveall;
2314 29785841 : unsigned ix;
2315 29785841 : rtx_insn *e0_last_head;
2316 29785841 : rtx cond;
2317 29785841 : rtx_insn *move_before;
2318 29785841 : unsigned nedges = EDGE_COUNT (bb->succs);
2319 29785841 : rtx_insn *jump = BB_END (bb);
2320 29785841 : regset live, live_union;
2321 :
2322 : /* Nothing to do if there is not at least two outgoing edges. */
2323 29785841 : if (nedges < 2)
2324 : return false;
2325 :
2326 : /* Don't crossjump if this block ends in a computed jump,
2327 : unless we are optimizing for size. */
2328 15296538 : if (optimize_bb_for_size_p (bb)
2329 1759681 : && bb != EXIT_BLOCK_PTR_FOR_FN (cfun)
2330 17056219 : && computed_jump_p (BB_END (bb)))
2331 : return false;
2332 :
2333 15296510 : cond = get_condition (jump, &move_before, true, false);
2334 15296510 : if (cond == NULL_RTX)
2335 2106698 : move_before = jump;
2336 :
2337 46156669 : for (ix = 0; ix < nedges; ix++)
2338 30860159 : if (EDGE_SUCC (bb, ix)->dest == EXIT_BLOCK_PTR_FOR_FN (cfun))
2339 : return false;
2340 :
2341 28419204 : for (ix = 0; ix < nedges; ix++)
2342 : {
2343 23758106 : edge e = EDGE_SUCC (bb, ix);
2344 23758106 : basic_block other_bb = e->dest;
2345 :
2346 23758106 : if (df_get_bb_dirty (other_bb))
2347 : {
2348 547639 : block_was_dirty = true;
2349 547639 : return false;
2350 : }
2351 :
2352 23210467 : if (e->flags & EDGE_ABNORMAL)
2353 : return false;
2354 :
2355 : /* Normally, all destination blocks must only be reachable from this
2356 : block, i.e. they must have one incoming edge.
2357 :
2358 : There is one special case we can handle, that of multiple consecutive
2359 : jumps where the first jumps to one of the targets of the second jump.
2360 : This happens frequently in switch statements for default labels.
2361 : The structure is as follows:
2362 : FINAL_DEST_BB
2363 : ....
2364 : if (cond) jump A;
2365 : fall through
2366 : BB
2367 : jump with targets A, B, C, D...
2368 : A
2369 : has two incoming edges, from FINAL_DEST_BB and BB
2370 :
2371 : In this case, we can try to move the insns through BB and into
2372 : FINAL_DEST_BB. */
2373 21180662 : if (EDGE_COUNT (other_bb->preds) != 1)
2374 : {
2375 8423589 : edge incoming_edge, incoming_bb_other_edge;
2376 8423589 : edge_iterator ei;
2377 :
2378 8423589 : if (final_dest_bb != NULL
2379 8423589 : || EDGE_COUNT (other_bb->preds) != 2)
2380 8057968 : return false;
2381 :
2382 : /* We must be able to move the insns across the whole block. */
2383 4637010 : move_before = BB_HEAD (bb);
2384 31781908 : while (!NONDEBUG_INSN_P (move_before))
2385 27144898 : move_before = NEXT_INSN (move_before);
2386 :
2387 4637010 : if (EDGE_COUNT (bb->preds) != 1)
2388 : return false;
2389 2770812 : incoming_edge = EDGE_PRED (bb, 0);
2390 2770812 : final_dest_bb = incoming_edge->src;
2391 10347325 : if (EDGE_COUNT (final_dest_bb->succs) != 2)
2392 : return false;
2393 3282178 : FOR_EACH_EDGE (incoming_bb_other_edge, ei, final_dest_bb->succs)
2394 3282178 : if (incoming_bb_other_edge != incoming_edge)
2395 : break;
2396 2289357 : if (incoming_bb_other_edge->dest != other_bb)
2397 : return false;
2398 : }
2399 : }
2400 :
2401 4661098 : e0 = EDGE_SUCC (bb, 0);
2402 4661098 : e0_last_head = NULL;
2403 4661098 : changed = false;
2404 :
2405 4780279 : for (ix = 1; ix < nedges; ix++)
2406 : {
2407 4665431 : edge e = EDGE_SUCC (bb, ix);
2408 4665431 : rtx_insn *e0_last, *e_last;
2409 4665431 : int nmatch;
2410 :
2411 4665431 : nmatch = flow_find_head_matching_sequence (e0->dest, e->dest,
2412 : &e0_last, &e_last, 0);
2413 4665431 : if (nmatch == 0)
2414 4546250 : return false;
2415 :
2416 119181 : if (nmatch < max_match)
2417 : {
2418 115666 : max_match = nmatch;
2419 115666 : e0_last_head = e0_last;
2420 : }
2421 : }
2422 :
2423 : /* If we matched an entire block, we probably have to avoid moving the
2424 : last insn. */
2425 114848 : if (max_match > 0
2426 114848 : && e0_last_head == BB_END (e0->dest)
2427 123762 : && (find_reg_note (e0_last_head, REG_EH_REGION, 0)
2428 7286 : || control_flow_insn_p (e0_last_head)))
2429 : {
2430 1640 : max_match--;
2431 1640 : if (max_match == 0)
2432 : return false;
2433 258 : e0_last_head = prev_real_nondebug_insn (e0_last_head);
2434 : }
2435 :
2436 113466 : if (max_match == 0)
2437 : return false;
2438 :
2439 : /* We must find a union of the live registers at each of the end points. */
2440 113466 : live = BITMAP_ALLOC (NULL);
2441 113466 : live_union = BITMAP_ALLOC (NULL);
2442 :
2443 113466 : currptr = XNEWVEC (rtx_insn *, nedges);
2444 113466 : headptr = XNEWVEC (rtx_insn *, nedges);
2445 113466 : nextptr = XNEWVEC (rtx_insn *, nedges);
2446 :
2447 343786 : for (ix = 0; ix < nedges; ix++)
2448 : {
2449 230320 : int j;
2450 230320 : basic_block merge_bb = EDGE_SUCC (bb, ix)->dest;
2451 230320 : rtx_insn *head = BB_HEAD (merge_bb);
2452 :
2453 1512040 : while (!NONDEBUG_INSN_P (head))
2454 1281720 : head = NEXT_INSN (head);
2455 230320 : headptr[ix] = head;
2456 230320 : currptr[ix] = head;
2457 :
2458 : /* Compute the end point and live information */
2459 371182 : for (j = 1; j < max_match; j++)
2460 201610 : do
2461 201610 : head = NEXT_INSN (head);
2462 201610 : while (!NONDEBUG_INSN_P (head));
2463 230320 : simulate_backwards_to_point (merge_bb, live, head);
2464 230320 : IOR_REG_SET (live_union, live);
2465 : }
2466 :
2467 : /* If we're moving across two blocks, verify the validity of the
2468 : first move, then adjust the target and let the loop below deal
2469 : with the final move. */
2470 113466 : if (final_dest_bb != NULL)
2471 : {
2472 7060 : rtx_insn *move_upto;
2473 :
2474 7060 : moveall = can_move_insns_across (currptr[0], e0_last_head, move_before,
2475 : jump, e0->dest, live_union,
2476 : NULL, &move_upto);
2477 7060 : if (!moveall)
2478 : {
2479 5487 : if (move_upto == NULL_RTX)
2480 5097 : goto out;
2481 :
2482 1244 : while (e0_last_head != move_upto)
2483 : {
2484 854 : df_simulate_one_insn_backwards (e0->dest, e0_last_head,
2485 : live_union);
2486 854 : e0_last_head = PREV_INSN (e0_last_head);
2487 : }
2488 : }
2489 1963 : if (e0_last_head == NULL_RTX)
2490 0 : goto out;
2491 :
2492 1963 : jump = BB_END (final_dest_bb);
2493 1963 : cond = get_condition (jump, &move_before, true, false);
2494 1963 : if (cond == NULL_RTX)
2495 0 : move_before = jump;
2496 : }
2497 :
2498 186414 : do
2499 : {
2500 186414 : rtx_insn *move_upto;
2501 186414 : moveall = can_move_insns_across (currptr[0], e0_last_head,
2502 : move_before, jump, e0->dest, live_union,
2503 : NULL, &move_upto);
2504 186414 : if (!moveall && move_upto == NULL_RTX)
2505 : {
2506 147092 : if (jump == move_before)
2507 : break;
2508 :
2509 : /* Try again, using a different insertion point. */
2510 74229 : move_before = jump;
2511 :
2512 74229 : continue;
2513 : }
2514 :
2515 39322 : if (final_dest_bb && !moveall)
2516 : /* We haven't checked whether a partial move would be OK for the first
2517 : move, so we have to fail this case. */
2518 : break;
2519 :
2520 58833 : changed = true;
2521 58833 : for (;;)
2522 : {
2523 58833 : if (currptr[0] == move_upto)
2524 : break;
2525 58882 : for (ix = 0; ix < nedges; ix++)
2526 : {
2527 39275 : rtx_insn *curr = currptr[ix];
2528 61835 : do
2529 61835 : curr = NEXT_INSN (curr);
2530 61835 : while (!NONDEBUG_INSN_P (curr));
2531 39275 : currptr[ix] = curr;
2532 : }
2533 : }
2534 :
2535 : /* If we can't currently move all of the identical insns, remember
2536 : each insn after the range that we'll merge. */
2537 39226 : if (!moveall)
2538 15381 : for (ix = 0; ix < nedges; ix++)
2539 : {
2540 10268 : rtx_insn *curr = currptr[ix];
2541 14218 : do
2542 14218 : curr = NEXT_INSN (curr);
2543 14218 : while (!NONDEBUG_INSN_P (curr));
2544 10268 : nextptr[ix] = curr;
2545 : }
2546 :
2547 39226 : reorder_insns (headptr[0], currptr[0], PREV_INSN (move_before));
2548 39226 : df_set_bb_dirty (EDGE_SUCC (bb, 0)->dest);
2549 39226 : if (final_dest_bb != NULL)
2550 1862 : df_set_bb_dirty (final_dest_bb);
2551 39226 : df_set_bb_dirty (bb);
2552 118883 : for (ix = 1; ix < nedges; ix++)
2553 : {
2554 40431 : df_set_bb_dirty (EDGE_SUCC (bb, ix)->dest);
2555 40431 : delete_insn_chain (headptr[ix], currptr[ix], false);
2556 : }
2557 39226 : if (!moveall)
2558 : {
2559 5113 : if (jump == move_before)
2560 : break;
2561 :
2562 : /* For the unmerged insns, try a different insertion point. */
2563 3816 : move_before = jump;
2564 :
2565 11448 : for (ix = 0; ix < nedges; ix++)
2566 7632 : currptr[ix] = headptr[ix] = nextptr[ix];
2567 : }
2568 : }
2569 112158 : while (!moveall);
2570 :
2571 34113 : out:
2572 113466 : free (currptr);
2573 113466 : free (headptr);
2574 113466 : free (nextptr);
2575 :
2576 113466 : crossjumps_occurred |= changed;
2577 :
2578 113466 : return changed;
2579 : }
2580 :
2581 : /* Return true if BB contains just bb note, or bb note followed
2582 : by only DEBUG_INSNs. */
2583 :
2584 : static bool
2585 16602479 : trivially_empty_bb_p (basic_block bb)
2586 : {
2587 16602479 : rtx_insn *insn = BB_END (bb);
2588 :
2589 5598 : while (1)
2590 : {
2591 16608077 : if (insn == BB_HEAD (bb))
2592 : return true;
2593 16607160 : if (!DEBUG_INSN_P (insn))
2594 : return false;
2595 5598 : insn = PREV_INSN (insn);
2596 : }
2597 : }
2598 :
2599 : /* Return true if BB contains just a return and possibly a USE of the
2600 : return value. Fill in *RET and *USE with the return and use insns
2601 : if any found, otherwise NULL. All CLOBBERs are ignored. */
2602 :
2603 : bool
2604 407645054 : bb_is_just_return (basic_block bb, rtx_insn **ret, rtx_insn **use)
2605 : {
2606 407645054 : *ret = *use = NULL;
2607 407645054 : rtx_insn *insn;
2608 :
2609 407645054 : if (bb == EXIT_BLOCK_PTR_FOR_FN (cfun))
2610 : return false;
2611 :
2612 541823425 : FOR_BB_INSNS_REVERSE (bb, insn)
2613 528390695 : if (NONDEBUG_INSN_P (insn))
2614 : {
2615 403189131 : rtx pat = PATTERN (insn);
2616 :
2617 403189131 : if (!*ret && ANY_RETURN_P (pat))
2618 7479176 : *ret = insn;
2619 7830956 : else if (*ret && !*use && GET_CODE (pat) == USE
2620 1136192 : && REG_P (XEXP (pat, 0))
2621 396846147 : && REG_FUNCTION_VALUE_P (XEXP (pat, 0)))
2622 1132978 : *use = insn;
2623 394576977 : else if (GET_CODE (pat) != CLOBBER)
2624 : return false;
2625 : }
2626 :
2627 13432730 : return !!*ret;
2628 : }
2629 :
2630 : /* Do simple CFG optimizations - basic block merging, simplifying of jump
2631 : instructions etc. Return nonzero if changes were made. */
2632 :
2633 : static bool
2634 22109724 : try_optimize_cfg (int mode)
2635 : {
2636 22109724 : bool changed_overall = false;
2637 22109724 : bool changed;
2638 22109724 : int iterations = 0;
2639 22109724 : basic_block bb, b, next;
2640 :
2641 22109724 : if (mode & (CLEANUP_CROSSJUMP | CLEANUP_THREADING))
2642 3018296 : clear_bb_flags ();
2643 :
2644 22109724 : crossjumps_occurred = false;
2645 :
2646 322175717 : FOR_EACH_BB_FN (bb, cfun)
2647 300065993 : update_forwarder_flag (bb);
2648 :
2649 22109724 : if (! targetm.cannot_modify_jumps_p ())
2650 : {
2651 22109724 : first_pass = true;
2652 : /* Attempt to merge blocks as made possible by edge removal. If
2653 : a block has only one successor, and the successor has only
2654 : one predecessor, they may be combined. */
2655 51988392 : do
2656 : {
2657 25994196 : block_was_dirty = false;
2658 25994196 : changed = false;
2659 25994196 : iterations++;
2660 :
2661 25994196 : if (dump_file)
2662 1771 : fprintf (dump_file,
2663 : "\n\ntry_optimize_cfg iteration %i\n\n",
2664 : iterations);
2665 :
2666 25994196 : for (b = ENTRY_BLOCK_PTR_FOR_FN (cfun)->next_bb; b
2667 435894840 : != EXIT_BLOCK_PTR_FOR_FN (cfun);)
2668 : {
2669 409900644 : basic_block c;
2670 409900644 : edge s;
2671 409900644 : bool changed_here = false;
2672 :
2673 : /* Delete trivially dead basic blocks. This is either
2674 : blocks with no predecessors, or empty blocks with no
2675 : successors. However if the empty block with no
2676 : successors is the successor of the ENTRY_BLOCK, it is
2677 : kept. This ensures that the ENTRY_BLOCK will have a
2678 : successor which is a precondition for many RTL
2679 : passes. Empty blocks may result from expanding
2680 : __builtin_unreachable (). */
2681 409900644 : if (EDGE_COUNT (b->preds) == 0
2682 409900644 : || (EDGE_COUNT (b->succs) == 0
2683 16602479 : && trivially_empty_bb_p (b)
2684 917 : && single_succ_edge (ENTRY_BLOCK_PTR_FOR_FN (cfun))->dest
2685 : != b))
2686 : {
2687 5553885 : c = b->prev_bb;
2688 5553885 : if (EDGE_COUNT (b->preds) > 0)
2689 : {
2690 917 : edge e;
2691 917 : edge_iterator ei;
2692 :
2693 917 : if (current_ir_type () == IR_RTL_CFGLAYOUT)
2694 : {
2695 51 : rtx_insn *insn;
2696 51 : for (insn = BB_FOOTER (b);
2697 51 : insn; insn = NEXT_INSN (insn))
2698 51 : if (BARRIER_P (insn))
2699 : break;
2700 51 : if (insn)
2701 102 : FOR_EACH_EDGE (e, ei, b->preds)
2702 51 : if ((e->flags & EDGE_FALLTHRU))
2703 : {
2704 51 : if (BB_FOOTER (b)
2705 51 : && BB_FOOTER (e->src) == NULL)
2706 : {
2707 51 : BB_FOOTER (e->src) = BB_FOOTER (b);
2708 51 : BB_FOOTER (b) = NULL;
2709 : }
2710 : else
2711 0 : emit_barrier_after_bb (e->src);
2712 : }
2713 : }
2714 : else
2715 : {
2716 866 : rtx_insn *last = get_last_bb_insn (b);
2717 866 : if (last && BARRIER_P (last))
2718 1732 : FOR_EACH_EDGE (e, ei, b->preds)
2719 866 : if ((e->flags & EDGE_FALLTHRU))
2720 866 : emit_barrier_after (BB_END (e->src));
2721 : }
2722 : }
2723 5553885 : delete_basic_block (b);
2724 5553885 : changed = true;
2725 : /* Avoid trying to remove the exit block. */
2726 5553885 : b = (c == ENTRY_BLOCK_PTR_FOR_FN (cfun) ? c->next_bb : c);
2727 5691068 : continue;
2728 5553885 : }
2729 :
2730 : /* Remove code labels no longer used. */
2731 404346759 : if (single_pred_p (b)
2732 293982749 : && (single_pred_edge (b)->flags & EDGE_FALLTHRU)
2733 207125701 : && !(single_pred_edge (b)->flags & EDGE_COMPLEX)
2734 204009446 : && LABEL_P (BB_HEAD (b))
2735 850215 : && !LABEL_PRESERVE_P (BB_HEAD (b))
2736 : /* If the previous block ends with a branch to this
2737 : block, we can't delete the label. Normally this
2738 : is a condjump that is yet to be simplified, but
2739 : if CASE_DROPS_THRU, this can be a tablejump with
2740 : some element going to the same place as the
2741 : default (fallthru). */
2742 405181888 : && (single_pred (b) == ENTRY_BLOCK_PTR_FOR_FN (cfun)
2743 835075 : || !JUMP_P (BB_END (single_pred (b)))
2744 637083 : || ! label_is_jump_target_p (BB_HEAD (b),
2745 637083 : BB_END (single_pred (b)))))
2746 : {
2747 828858 : delete_insn (BB_HEAD (b));
2748 828858 : if (dump_file)
2749 37 : fprintf (dump_file, "Deleted label in block %i.\n",
2750 : b->index);
2751 : }
2752 :
2753 : /* If we fall through an empty block, we can remove it. */
2754 404483942 : if (!(mode & (CLEANUP_CFGLAYOUT | CLEANUP_NO_INSN_DEL))
2755 86417288 : && single_pred_p (b)
2756 63937558 : && (single_pred_edge (b)->flags & EDGE_FALLTHRU)
2757 45173389 : && !LABEL_P (BB_HEAD (b))
2758 44807138 : && FORWARDER_BLOCK_P (b)
2759 : /* Note that forwarder_block_p true ensures that
2760 : there is a successor for this block. */
2761 5431895 : && (single_succ_edge (b)->flags & EDGE_FALLTHRU)
2762 404570204 : && n_basic_blocks_for_fn (cfun) > NUM_FIXED_BLOCKS + 1)
2763 : {
2764 137183 : if (dump_file)
2765 11 : fprintf (dump_file,
2766 : "Deleting fallthru block %i.\n",
2767 : b->index);
2768 :
2769 2664 : c = ((b->prev_bb == ENTRY_BLOCK_PTR_FOR_FN (cfun))
2770 137183 : ? b->next_bb : b->prev_bb);
2771 137183 : redirect_edge_succ_nodup (single_pred_edge (b),
2772 : single_succ (b));
2773 137183 : delete_basic_block (b);
2774 137183 : changed = true;
2775 137183 : b = c;
2776 137183 : continue;
2777 : }
2778 :
2779 : /* Merge B with its single successor, if any. */
2780 404209576 : if (single_succ_p (b)
2781 177106914 : && (s = single_succ_edge (b))
2782 177106914 : && !(s->flags & EDGE_COMPLEX)
2783 168073139 : && (c = s->dest) != EXIT_BLOCK_PTR_FOR_FN (cfun)
2784 413330844 : && single_pred_p (c)
2785 411629656 : && b != c)
2786 : {
2787 : /* When not in cfg_layout mode use code aware of reordering
2788 : INSN. This code possibly creates new basic blocks so it
2789 : does not fit merge_blocks interface and is kept here in
2790 : hope that it will become useless once more of compiler
2791 : is transformed to use cfg_layout mode. */
2792 :
2793 9121268 : if ((mode & CLEANUP_CFGLAYOUT)
2794 9121268 : && can_merge_blocks_p (b, c))
2795 : {
2796 819330 : merge_blocks (b, c);
2797 819330 : update_forwarder_flag (b);
2798 819330 : changed_here = true;
2799 : }
2800 8301938 : else if (!(mode & CLEANUP_CFGLAYOUT)
2801 : /* If the jump insn has side effects,
2802 : we can't kill the edge. */
2803 7024848 : && (!JUMP_P (BB_END (b))
2804 2367148 : || (reload_completed
2805 3222182 : ? simplejump_p (BB_END (b))
2806 855034 : : (onlyjump_p (BB_END (b))
2807 854217 : && !tablejump_p (BB_END (b),
2808 : NULL, NULL))))
2809 18546986 : && (next = merge_blocks_move (s, b, c, mode)))
2810 : {
2811 : b = next;
2812 : changed_here = true;
2813 : }
2814 : }
2815 :
2816 : /* Try to change a branch to a return to just that return. */
2817 404209576 : rtx_insn *ret, *use;
2818 404209576 : if (single_succ_p (b)
2819 175446581 : && onlyjump_p (BB_END (b))
2820 431943054 : && bb_is_just_return (single_succ (b), &ret, &use))
2821 : {
2822 37528 : if (redirect_jump (as_a <rtx_jump_insn *> (BB_END (b)),
2823 37528 : PATTERN (ret), 0))
2824 : {
2825 37528 : if (use)
2826 22138 : emit_insn_before (copy_insn (PATTERN (use)),
2827 22138 : BB_END (b));
2828 37528 : if (dump_file)
2829 23 : fprintf (dump_file, "Changed jump %d->%d to return.\n",
2830 23 : b->index, single_succ (b)->index);
2831 37528 : redirect_edge_succ (single_succ_edge (b),
2832 37528 : EXIT_BLOCK_PTR_FOR_FN (cfun));
2833 37528 : single_succ_edge (b)->flags &= ~EDGE_CROSSING;
2834 37528 : changed_here = true;
2835 : }
2836 : }
2837 :
2838 : /* Try to change a conditional branch to a return to the
2839 : respective conditional return. */
2840 404209576 : if (EDGE_COUNT (b->succs) == 2
2841 211726206 : && any_condjump_p (BB_END (b))
2842 589435886 : && bb_is_just_return (BRANCH_EDGE (b)->dest, &ret, &use))
2843 : {
2844 590697 : if (redirect_jump (as_a <rtx_jump_insn *> (BB_END (b)),
2845 590697 : PATTERN (ret), 0))
2846 : {
2847 0 : if (use)
2848 0 : emit_insn_before (copy_insn (PATTERN (use)),
2849 0 : BB_END (b));
2850 0 : if (dump_file)
2851 0 : fprintf (dump_file, "Changed conditional jump %d->%d "
2852 : "to conditional return.\n",
2853 0 : b->index, BRANCH_EDGE (b)->dest->index);
2854 0 : redirect_edge_succ (BRANCH_EDGE (b),
2855 0 : EXIT_BLOCK_PTR_FOR_FN (cfun));
2856 0 : BRANCH_EDGE (b)->flags &= ~EDGE_CROSSING;
2857 0 : changed_here = true;
2858 : }
2859 : }
2860 :
2861 : /* Try to flip a conditional branch that falls through to
2862 : a return so that it becomes a conditional return and a
2863 : new jump to the original branch target. */
2864 404209576 : if (EDGE_COUNT (b->succs) == 2
2865 211726206 : && BRANCH_EDGE (b)->dest != EXIT_BLOCK_PTR_FOR_FN (cfun)
2866 211726206 : && any_condjump_p (BB_END (b))
2867 589435886 : && bb_is_just_return (FALLTHRU_EDGE (b)->dest, &ret, &use))
2868 : {
2869 160864 : if (invert_jump (as_a <rtx_jump_insn *> (BB_END (b)),
2870 160864 : JUMP_LABEL (BB_END (b)), 0))
2871 : {
2872 160864 : basic_block new_ft = BRANCH_EDGE (b)->dest;
2873 160864 : if (redirect_jump (as_a <rtx_jump_insn *> (BB_END (b)),
2874 160864 : PATTERN (ret), 0))
2875 : {
2876 0 : if (use)
2877 0 : emit_insn_before (copy_insn (PATTERN (use)),
2878 0 : BB_END (b));
2879 0 : if (dump_file)
2880 0 : fprintf (dump_file, "Changed conditional jump "
2881 : "%d->%d to conditional return, adding "
2882 : "fall-through jump.\n",
2883 0 : b->index, BRANCH_EDGE (b)->dest->index);
2884 0 : redirect_edge_succ (BRANCH_EDGE (b),
2885 0 : EXIT_BLOCK_PTR_FOR_FN (cfun));
2886 0 : BRANCH_EDGE (b)->flags &= ~EDGE_CROSSING;
2887 0 : std::swap (BRANCH_EDGE (b)->probability,
2888 0 : FALLTHRU_EDGE (b)->probability);
2889 0 : update_br_prob_note (b);
2890 0 : basic_block jb = force_nonfallthru (FALLTHRU_EDGE (b));
2891 0 : notice_new_block (jb);
2892 0 : if (!redirect_jump (as_a <rtx_jump_insn *> (BB_END (jb)),
2893 0 : block_label (new_ft), 0))
2894 0 : gcc_unreachable ();
2895 0 : redirect_edge_succ (single_succ_edge (jb), new_ft);
2896 0 : changed_here = true;
2897 : }
2898 : else
2899 : {
2900 : /* Invert the jump back to what it was. This should
2901 : never fail. */
2902 160864 : if (!invert_jump (as_a <rtx_jump_insn *> (BB_END (b)),
2903 160864 : JUMP_LABEL (BB_END (b)), 0))
2904 0 : gcc_unreachable ();
2905 : }
2906 : }
2907 : }
2908 :
2909 : /* Simplify branch over branch. */
2910 404209576 : if ((mode & CLEANUP_EXPENSIVE)
2911 106942964 : && !(mode & CLEANUP_CFGLAYOUT)
2912 438895013 : && try_simplify_condjump (b))
2913 : changed_here = true;
2914 :
2915 : /* If B has a single outgoing edge, but uses a
2916 : non-trivial jump instruction without side-effects, we
2917 : can either delete the jump entirely, or replace it
2918 : with a simple unconditional jump. */
2919 404209576 : if (single_succ_p (b)
2920 175446617 : && single_succ (b) != EXIT_BLOCK_PTR_FOR_FN (cfun)
2921 145326728 : && onlyjump_p (BB_END (b))
2922 29465852 : && !CROSSING_JUMP_P (BB_END (b))
2923 430691238 : && try_redirect_by_replacing_jump (single_succ_edge (b),
2924 : single_succ (b),
2925 28252170 : (mode & CLEANUP_CFGLAYOUT) != 0))
2926 : {
2927 4294574 : update_forwarder_flag (b);
2928 4294574 : changed_here = true;
2929 : }
2930 :
2931 : /* Simplify branch to branch. */
2932 404209576 : if (try_forward_edges (mode, b))
2933 : {
2934 6480440 : update_forwarder_flag (b);
2935 6480440 : changed_here = true;
2936 : }
2937 :
2938 : /* Look for shared code between blocks. */
2939 404209576 : if ((mode & CLEANUP_CROSSJUMP)
2940 404209576 : && try_crossjump_bb (mode, b))
2941 : changed_here = true;
2942 :
2943 404209576 : if ((mode & CLEANUP_CROSSJUMP)
2944 : /* This can lengthen register lifetimes. Do it only after
2945 : reload. */
2946 29785841 : && reload_completed
2947 433995417 : && try_head_merge_bb (b))
2948 : changed_here = true;
2949 :
2950 : /* Don't get confused by the index shift caused by
2951 : deleting blocks. */
2952 404171223 : if (!changed_here)
2953 389261677 : b = b->next_bb;
2954 : else
2955 : changed = true;
2956 : }
2957 :
2958 25994196 : if ((mode & CLEANUP_CROSSJUMP)
2959 25994196 : && try_crossjump_bb (mode, EXIT_BLOCK_PTR_FOR_FN (cfun)))
2960 : changed = true;
2961 :
2962 25994196 : if (block_was_dirty)
2963 : {
2964 : /* This should only be set by head-merging. */
2965 196361 : gcc_assert (mode & CLEANUP_CROSSJUMP);
2966 196361 : df_analyze ();
2967 : }
2968 :
2969 25994196 : if (changed)
2970 : {
2971 : /* Edge forwarding in particular can cause hot blocks previously
2972 : reached by both hot and cold blocks to become dominated only
2973 : by cold blocks. This will cause the verification below to fail,
2974 : and lead to now cold code in the hot section. This is not easy
2975 : to detect and fix during edge forwarding, and in some cases
2976 : is only visible after newly unreachable blocks are deleted,
2977 : which will be done in fixup_partitions. */
2978 3884472 : if ((mode & CLEANUP_NO_PARTITIONING) == 0)
2979 : {
2980 3746132 : fixup_partitions ();
2981 3746132 : checking_verify_flow_info ();
2982 : }
2983 : }
2984 :
2985 25994196 : changed_overall |= changed;
2986 25994196 : first_pass = false;
2987 : }
2988 : while (changed);
2989 : }
2990 :
2991 356119487 : FOR_ALL_BB_FN (b, cfun)
2992 334009763 : b->flags &= ~(BB_FORWARDER_BLOCK | BB_NONTHREADABLE_BLOCK);
2993 :
2994 22109724 : return changed_overall;
2995 : }
2996 :
2997 : /* Delete all unreachable basic blocks. */
2998 :
2999 : bool
3000 28554415 : delete_unreachable_blocks (void)
3001 : {
3002 28554415 : bool changed = false;
3003 28554415 : basic_block b, prev_bb;
3004 :
3005 28554415 : find_unreachable_blocks ();
3006 :
3007 : /* When we're in GIMPLE mode and there may be debug bind insns, we
3008 : should delete blocks in reverse dominator order, so as to get a
3009 : chance to substitute all released DEFs into debug bind stmts. If
3010 : we don't have dominators information, walking blocks backward
3011 : gets us a better chance of retaining most debug information than
3012 : otherwise. */
3013 12941905 : if (MAY_HAVE_DEBUG_BIND_INSNS && current_ir_type () == IR_GIMPLE
3014 28826075 : && dom_info_available_p (CDI_DOMINATORS))
3015 : {
3016 0 : for (b = EXIT_BLOCK_PTR_FOR_FN (cfun)->prev_bb;
3017 0 : b != ENTRY_BLOCK_PTR_FOR_FN (cfun); b = prev_bb)
3018 : {
3019 0 : prev_bb = b->prev_bb;
3020 :
3021 0 : if (!(b->flags & BB_REACHABLE))
3022 : {
3023 : /* Speed up the removal of blocks that don't dominate
3024 : others. Walking backwards, this should be the common
3025 : case. */
3026 0 : if (!first_dom_son (CDI_DOMINATORS, b))
3027 0 : delete_basic_block (b);
3028 : else
3029 : {
3030 0 : auto_vec<basic_block> h
3031 0 : = get_all_dominated_blocks (CDI_DOMINATORS, b);
3032 :
3033 0 : while (h.length ())
3034 : {
3035 0 : b = h.pop ();
3036 :
3037 0 : prev_bb = b->prev_bb;
3038 :
3039 0 : gcc_assert (!(b->flags & BB_REACHABLE));
3040 :
3041 0 : delete_basic_block (b);
3042 : }
3043 0 : }
3044 :
3045 : changed = true;
3046 : }
3047 : }
3048 : }
3049 : else
3050 : {
3051 28554415 : for (b = EXIT_BLOCK_PTR_FOR_FN (cfun)->prev_bb;
3052 423315774 : b != ENTRY_BLOCK_PTR_FOR_FN (cfun); b = prev_bb)
3053 : {
3054 394761359 : prev_bb = b->prev_bb;
3055 :
3056 394761359 : if (!(b->flags & BB_REACHABLE))
3057 : {
3058 1698264 : delete_basic_block (b);
3059 1698264 : changed = true;
3060 : }
3061 : }
3062 : }
3063 :
3064 28554415 : if (changed)
3065 462864 : tidy_fallthru_edges ();
3066 28554415 : return changed;
3067 : }
3068 :
3069 : /* Delete any jump tables never referenced. We can't delete them at the
3070 : time of removing tablejump insn as they are referenced by the preceding
3071 : insns computing the destination, so we delay deleting and garbagecollect
3072 : them once life information is computed. */
3073 : void
3074 9269945 : delete_dead_jumptables (void)
3075 : {
3076 9269945 : basic_block bb;
3077 :
3078 : /* A dead jump table does not belong to any basic block. Scan insns
3079 : between two adjacent basic blocks. */
3080 103041080 : FOR_EACH_BB_FN (bb, cfun)
3081 : {
3082 93771135 : rtx_insn *insn, *next;
3083 :
3084 93771135 : for (insn = NEXT_INSN (BB_END (bb));
3085 171559898 : insn && !NOTE_INSN_BASIC_BLOCK_P (insn);
3086 : insn = next)
3087 : {
3088 77788763 : next = NEXT_INSN (insn);
3089 77788763 : if (LABEL_P (insn)
3090 44067383 : && LABEL_NUSES (insn) == LABEL_PRESERVE_P (insn)
3091 79728110 : && JUMP_TABLE_DATA_P (next))
3092 : {
3093 0 : rtx_insn *label = insn, *jump = next;
3094 :
3095 0 : if (dump_file)
3096 0 : fprintf (dump_file, "Dead jumptable %i removed\n",
3097 0 : INSN_UID (insn));
3098 :
3099 0 : next = NEXT_INSN (next);
3100 0 : delete_insn (jump);
3101 0 : delete_insn (label);
3102 : }
3103 : }
3104 : }
3105 9269945 : }
3106 :
3107 :
3108 : /* Tidy the CFG by deleting unreachable code and whatnot. */
3109 :
3110 : bool
3111 19926754 : cleanup_cfg (int mode)
3112 : {
3113 19926754 : bool changed = false;
3114 :
3115 : /* Set the cfglayout mode flag here. We could update all the callers
3116 : but that is just inconvenient, especially given that we eventually
3117 : want to have cfglayout mode as the default. */
3118 19926754 : if (current_ir_type () == IR_RTL_CFGLAYOUT)
3119 13219128 : mode |= CLEANUP_CFGLAYOUT;
3120 :
3121 19926754 : timevar_push (TV_CLEANUP_CFG);
3122 19926754 : if (delete_unreachable_blocks ())
3123 : {
3124 157190 : changed = true;
3125 : /* We've possibly created trivially dead code. Cleanup it right
3126 : now to introduce more opportunities for try_optimize_cfg. */
3127 157190 : if (!(mode & (CLEANUP_NO_INSN_DEL))
3128 41899 : && !reload_completed)
3129 41819 : delete_trivially_dead_insns (get_insns (), max_reg_num ());
3130 : }
3131 :
3132 19926754 : compact_blocks ();
3133 :
3134 : /* To tail-merge blocks ending in the same noreturn function (e.g.
3135 : a call to abort) we have to insert fake edges to exit. Do this
3136 : here once. The fake edges do not interfere with any other CFG
3137 : cleanups. */
3138 19926754 : if (mode & CLEANUP_CROSSJUMP)
3139 976484 : add_noreturn_fake_exit_edges ();
3140 :
3141 19926754 : if (!dbg_cnt (cfg_cleanup))
3142 : return changed;
3143 :
3144 22109724 : while (try_optimize_cfg (mode))
3145 : {
3146 3795426 : delete_unreachable_blocks (), changed = true;
3147 3795426 : if (!(mode & CLEANUP_NO_INSN_DEL))
3148 : {
3149 : /* Try to remove some trivially dead insns when doing an expensive
3150 : cleanup. But delete_trivially_dead_insns doesn't work after
3151 : reload (it only handles pseudos) and run_fast_dce is too costly
3152 : to run in every iteration.
3153 :
3154 : For effective cross jumping, we really want to run a fast DCE to
3155 : clean up any dead conditions, or they get in the way of performing
3156 : useful tail merges.
3157 :
3158 : Other transformations in cleanup_cfg are not so sensitive to dead
3159 : code, so delete_trivially_dead_insns or even doing nothing at all
3160 : is good enough. */
3161 640226 : if ((mode & CLEANUP_EXPENSIVE) && !reload_completed
3162 2245394 : && !delete_trivially_dead_insns (get_insns (), max_reg_num ()))
3163 : break;
3164 2182970 : if ((mode & CLEANUP_CROSSJUMP) && crossjumps_occurred)
3165 : {
3166 79764 : run_fast_dce ();
3167 79764 : mode &= ~CLEANUP_FORCE_FAST_DCE;
3168 : }
3169 : }
3170 : else
3171 : break;
3172 : }
3173 :
3174 19926754 : if (mode & CLEANUP_CROSSJUMP)
3175 976484 : remove_fake_exit_edges ();
3176 :
3177 19926754 : if (mode & CLEANUP_FORCE_FAST_DCE)
3178 118545 : run_fast_dce ();
3179 :
3180 : /* Don't call delete_dead_jumptables in cfglayout mode, because
3181 : that function assumes that jump tables are in the insns stream.
3182 : But we also don't _have_ to delete dead jumptables in cfglayout
3183 : mode because we shouldn't even be looking at things that are
3184 : not in a basic block. Dead jumptables are cleaned up when
3185 : going out of cfglayout mode. */
3186 19926754 : if (!(mode & CLEANUP_CFGLAYOUT))
3187 6707626 : delete_dead_jumptables ();
3188 :
3189 : /* ??? We probably do this way too often. */
3190 19926754 : if (current_loops
3191 9286881 : && (changed
3192 6857413 : || (mode & CLEANUP_CFG_CHANGED)))
3193 : {
3194 2521715 : timevar_push (TV_REPAIR_LOOPS);
3195 : /* The above doesn't preserve dominance info if available. */
3196 2521715 : gcc_assert (!dom_info_available_p (CDI_DOMINATORS));
3197 2521715 : calculate_dominance_info (CDI_DOMINATORS);
3198 2521715 : fix_loop_structure (NULL);
3199 2521715 : free_dominance_info (CDI_DOMINATORS);
3200 2521715 : timevar_pop (TV_REPAIR_LOOPS);
3201 : }
3202 :
3203 19926754 : timevar_pop (TV_CLEANUP_CFG);
3204 :
3205 19926754 : return changed;
3206 : }
3207 :
3208 : namespace {
3209 :
3210 : const pass_data pass_data_jump =
3211 : {
3212 : RTL_PASS, /* type */
3213 : "jump", /* name */
3214 : OPTGROUP_NONE, /* optinfo_flags */
3215 : TV_JUMP, /* tv_id */
3216 : 0, /* properties_required */
3217 : 0, /* properties_provided */
3218 : 0, /* properties_destroyed */
3219 : 0, /* todo_flags_start */
3220 : 0, /* todo_flags_finish */
3221 : };
3222 :
3223 : class pass_jump : public rtl_opt_pass
3224 : {
3225 : public:
3226 292371 : pass_jump (gcc::context *ctxt)
3227 584742 : : rtl_opt_pass (pass_data_jump, ctxt)
3228 : {}
3229 :
3230 : /* opt_pass methods: */
3231 : unsigned int execute (function *) final override;
3232 :
3233 : }; // class pass_jump
3234 :
3235 : unsigned int
3236 1504947 : pass_jump::execute (function *)
3237 : {
3238 1504947 : delete_trivially_dead_insns (get_insns (), max_reg_num ());
3239 1504947 : if (dump_file)
3240 84 : dump_flow_info (dump_file, dump_flags);
3241 3009894 : cleanup_cfg ((optimize ? CLEANUP_EXPENSIVE : 0)
3242 1056939 : | (flag_thread_jumps && flag_expensive_optimizations
3243 1504947 : ? CLEANUP_THREADING : 0));
3244 1504947 : return 0;
3245 : }
3246 :
3247 : } // anon namespace
3248 :
3249 : rtl_opt_pass *
3250 292371 : make_pass_jump (gcc::context *ctxt)
3251 : {
3252 292371 : return new pass_jump (ctxt);
3253 : }
3254 :
3255 : namespace {
3256 :
3257 : const pass_data pass_data_jump_after_combine =
3258 : {
3259 : RTL_PASS, /* type */
3260 : "jump_after_combine", /* name */
3261 : OPTGROUP_NONE, /* optinfo_flags */
3262 : TV_JUMP, /* tv_id */
3263 : 0, /* properties_required */
3264 : 0, /* properties_provided */
3265 : 0, /* properties_destroyed */
3266 : 0, /* todo_flags_start */
3267 : 0, /* todo_flags_finish */
3268 : };
3269 :
3270 : class pass_jump_after_combine : public rtl_opt_pass
3271 : {
3272 : public:
3273 292371 : pass_jump_after_combine (gcc::context *ctxt)
3274 584742 : : rtl_opt_pass (pass_data_jump_after_combine, ctxt)
3275 : {}
3276 :
3277 : /* opt_pass methods: */
3278 1504958 : bool gate (function *) final override
3279 : {
3280 1504958 : return flag_thread_jumps && flag_expensive_optimizations;
3281 : }
3282 : unsigned int execute (function *) final override;
3283 :
3284 : }; // class pass_jump_after_combine
3285 :
3286 : unsigned int
3287 976339 : pass_jump_after_combine::execute (function *)
3288 : {
3289 : /* Jump threading does not keep dominators up-to-date. */
3290 976339 : free_dominance_info (CDI_DOMINATORS);
3291 976339 : cleanup_cfg (CLEANUP_THREADING);
3292 976339 : return 0;
3293 : }
3294 :
3295 : } // anon namespace
3296 :
3297 : rtl_opt_pass *
3298 292371 : make_pass_jump_after_combine (gcc::context *ctxt)
3299 : {
3300 292371 : return new pass_jump_after_combine (ctxt);
3301 : }
3302 :
3303 : namespace {
3304 :
3305 : const pass_data pass_data_jump2 =
3306 : {
3307 : RTL_PASS, /* type */
3308 : "jump2", /* name */
3309 : OPTGROUP_NONE, /* optinfo_flags */
3310 : TV_JUMP, /* tv_id */
3311 : 0, /* properties_required */
3312 : 0, /* properties_provided */
3313 : 0, /* properties_destroyed */
3314 : 0, /* todo_flags_start */
3315 : 0, /* todo_flags_finish */
3316 : };
3317 :
3318 : class pass_jump2 : public rtl_opt_pass
3319 : {
3320 : public:
3321 292371 : pass_jump2 (gcc::context *ctxt)
3322 584742 : : rtl_opt_pass (pass_data_jump2, ctxt)
3323 : {}
3324 :
3325 : /* opt_pass methods: */
3326 1504951 : unsigned int execute (function *) final override
3327 : {
3328 2033418 : cleanup_cfg (flag_crossjumping ? CLEANUP_CROSSJUMP : 0);
3329 1504951 : return 0;
3330 : }
3331 :
3332 : }; // class pass_jump2
3333 :
3334 : } // anon namespace
3335 :
3336 : rtl_opt_pass *
3337 292371 : make_pass_jump2 (gcc::context *ctxt)
3338 : {
3339 292371 : return new pass_jump2 (ctxt);
3340 : }
|
