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 20925 : notice_new_block (basic_block bb)
90 : {
91 20925 : if (!bb)
92 : return;
93 :
94 14990 : if (forwarder_block_p (bb))
95 14990 : bb->flags |= BB_FORWARDER_BLOCK;
96 : }
97 :
98 : /* Recompute forwarder flag after block has been modified. */
99 :
100 : static void
101 312031218 : update_forwarder_flag (basic_block bb)
102 : {
103 312031218 : if (forwarder_block_p (bb))
104 16368453 : bb->flags |= BB_FORWARDER_BLOCK;
105 : else
106 295662765 : bb->flags &= ~BB_FORWARDER_BLOCK;
107 312031218 : }
108 :
109 : /* Simplify a conditional jump around an unconditional jump.
110 : Return true if something changed. */
111 :
112 : static bool
113 34007681 : try_simplify_condjump (basic_block cbranch_block)
114 : {
115 34007681 : basic_block jump_block, jump_dest_block, cbranch_dest_block;
116 34007681 : edge cbranch_jump_edge, cbranch_fallthru_edge;
117 34007681 : rtx_insn *cbranch_insn;
118 :
119 : /* Verify that there are exactly two successors. */
120 34007681 : 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 17080731 : cbranch_insn = BB_END (cbranch_block);
126 17080731 : if (!any_condjump_p (cbranch_insn))
127 : return false;
128 :
129 15050793 : cbranch_fallthru_edge = FALLTHRU_EDGE (cbranch_block);
130 15050793 : 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 15050793 : jump_block = cbranch_fallthru_edge->dest;
136 49051356 : if (!single_pred_p (jump_block)
137 13379922 : || jump_block->next_bb == EXIT_BLOCK_PTR_FOR_FN (cfun)
138 28265728 : || !FORWARDER_BLOCK_P (jump_block))
139 : return false;
140 1691454 : 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 1691454 : if (BB_PARTITION (jump_block) != BB_PARTITION (jump_dest_block)
153 1651467 : || (cbranch_jump_edge->flags & EDGE_CROSSING))
154 : return false;
155 :
156 : /* The conditional branch must target the block after the
157 : unconditional branch. */
158 1424357 : cbranch_dest_block = cbranch_jump_edge->dest;
159 :
160 1424357 : if (cbranch_dest_block == EXIT_BLOCK_PTR_FOR_FN (cfun)
161 1424357 : || jump_dest_block == EXIT_BLOCK_PTR_FOR_FN (cfun)
162 2847876 : || !can_fallthru (jump_block, cbranch_dest_block))
163 1417239 : return false;
164 :
165 : /* Invert the conditional branch. */
166 7118 : if (!invert_jump (as_a <rtx_jump_insn *> (cbranch_insn),
167 7118 : block_label (jump_dest_block), 0))
168 : return false;
169 :
170 7118 : 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 7118 : cbranch_jump_edge = redirect_edge_succ_nodup (cbranch_jump_edge,
178 : cbranch_dest_block);
179 7118 : cbranch_fallthru_edge = redirect_edge_succ_nodup (cbranch_fallthru_edge,
180 : jump_dest_block);
181 7118 : cbranch_jump_edge->flags |= EDGE_FALLTHRU;
182 7118 : cbranch_fallthru_edge->flags &= ~EDGE_FALLTHRU;
183 7118 : update_br_prob_note (cbranch_block);
184 :
185 : /* Delete the block with the unconditional jump, and clean up the mess. */
186 7118 : delete_basic_block (jump_block);
187 7118 : tidy_fallthru_edge (cbranch_jump_edge);
188 7118 : update_forwarder_flag (cbranch_block);
189 :
190 7118 : 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 32951742 : mark_effect (rtx exp, regset nonequal)
198 : {
199 32951742 : rtx dest;
200 32951742 : 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 2465323 : case CLOBBER:
205 2465323 : dest = XEXP (exp, 0);
206 2465323 : if (REG_P (dest))
207 2432428 : bitmap_clear_range (nonequal, REGNO (dest), REG_NREGS (dest));
208 : return false;
209 :
210 11128988 : case SET:
211 11128988 : if (cselib_redundant_set_p (exp))
212 : return false;
213 10943406 : dest = SET_DEST (exp);
214 10943406 : if (dest == pc_rtx)
215 : return false;
216 10936205 : if (!REG_P (dest))
217 : return true;
218 10353222 : bitmap_set_range (nonequal, REGNO (dest), REG_NREGS (dest));
219 10353222 : 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 3570338 : mentions_nonequal_regs (const_rtx x, regset nonequal)
229 : {
230 3570338 : subrtx_iterator::array_type array;
231 7156042 : FOR_EACH_SUBRTX (iter, array, x, NONCONST)
232 : {
233 7148841 : const_rtx x = *iter;
234 7148841 : if (REG_P (x))
235 : {
236 3570579 : unsigned int end_regno = END_REGNO (x);
237 3578021 : for (unsigned int regno = REGNO (x); regno < end_regno; ++regno)
238 3570579 : if (REGNO_REG_SET_P (nonequal, regno))
239 3563137 : return true;
240 : }
241 : }
242 7201 : return false;
243 3570338 : }
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 28173159 : thread_jump (edge e, basic_block b)
251 : {
252 28173159 : rtx set1, set2, cond1, cond2;
253 28173159 : rtx_insn *insn;
254 28173159 : enum rtx_code code1, code2, reversed_code2;
255 28173159 : bool reverse1 = false;
256 28173159 : unsigned i;
257 28173159 : regset nonequal;
258 28173159 : bool failed = false;
259 :
260 : /* Jump threading may cause fixup_partitions to introduce new crossing edges,
261 : which is not allowed after reload. */
262 28173159 : gcc_checking_assert (!reload_completed || !crtl->has_bb_partition);
263 :
264 28173159 : 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 45147316 : if (EDGE_COUNT (e->src->succs) != 2)
270 : return NULL;
271 16980747 : if (EDGE_COUNT (b->succs) != 2)
272 : {
273 7511377 : b->flags |= BB_NONTHREADABLE_BLOCK;
274 7511377 : return NULL;
275 : }
276 :
277 : /* Second branch must end with onlyjump, as we will eliminate the jump. */
278 9469370 : if (!any_condjump_p (BB_END (e->src)))
279 : return NULL;
280 :
281 8663610 : if (!any_condjump_p (BB_END (b)) || !onlyjump_p (BB_END (b)))
282 : {
283 614311 : b->flags |= BB_NONTHREADABLE_BLOCK;
284 614311 : return NULL;
285 : }
286 :
287 8049299 : set1 = pc_set (BB_END (e->src));
288 8049299 : set2 = pc_set (BB_END (b));
289 8049299 : if (((e->flags & EDGE_FALLTHRU) != 0)
290 8049299 : != (XEXP (SET_SRC (set1), 1) == pc_rtx))
291 3960797 : reverse1 = true;
292 :
293 8049299 : cond1 = XEXP (SET_SRC (set1), 0);
294 8049299 : cond2 = XEXP (SET_SRC (set2), 0);
295 8049299 : if (reverse1)
296 3960797 : code1 = reversed_comparison_code (cond1, BB_END (e->src));
297 : else
298 4088502 : code1 = GET_CODE (cond1);
299 :
300 8049299 : code2 = GET_CODE (cond2);
301 8049299 : reversed_code2 = reversed_comparison_code (cond2, BB_END (b));
302 :
303 8049299 : if (!comparison_dominates_p (code1, code2)
304 8049299 : && !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 6483672 : if (!rtx_equal_p (XEXP (cond1, 0), XEXP (cond2, 0))
312 6483672 : || !rtx_equal_p (XEXP (cond1, 1), XEXP (cond2, 1)))
313 914349 : return NULL;
314 :
315 : /* Punt if BB_END (e->src) is doloop-like conditional jump that modifies
316 : the registers used in cond1. */
317 5569323 : 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 63664119 : for (insn = NEXT_INSN (BB_HEAD (b)); insn != NEXT_INSN (BB_END (b));
323 52525473 : insn = NEXT_INSN (insn))
324 53941475 : if (INSN_P (insn) && side_effects_p (PATTERN (insn)))
325 : {
326 1416002 : b->flags |= BB_NONTHREADABLE_BLOCK;
327 1416002 : return NULL;
328 : }
329 :
330 4153321 : cselib_init (0);
331 :
332 : /* First process all values computed in the source basic block. */
333 58619215 : for (insn = NEXT_INSN (BB_HEAD (e->src));
334 58619215 : insn != NEXT_INSN (BB_END (e->src));
335 54465894 : insn = NEXT_INSN (insn))
336 54465894 : if (INSN_P (insn))
337 50728574 : cselib_process_insn (insn);
338 :
339 4153321 : nonequal = BITMAP_ALLOC (NULL);
340 4153321 : 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 37656318 : for (insn = NEXT_INSN (BB_HEAD (b));
347 37656318 : insn != NEXT_INSN (BB_END (b)) && !failed;
348 33502997 : 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 37066134 : if (insn == BB_END (b)
354 37066134 : && mentions_nonequal_regs (cond2, nonequal))
355 3563137 : goto failed_exit;
356 :
357 33502997 : if (INSN_P (insn))
358 : {
359 30395158 : rtx pat = PATTERN (insn);
360 :
361 30395158 : if (GET_CODE (pat) == PARALLEL)
362 : {
363 7506580 : for (i = 0; i < (unsigned)XVECLEN (pat, 0); i++)
364 5031582 : failed |= mark_effect (XVECEXP (pat, 0, i), nonequal);
365 : }
366 : else
367 27920160 : failed |= mark_effect (pat, nonequal);
368 : }
369 :
370 33502997 : 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 590184 : if (failed)
376 : {
377 582983 : b->flags |= BB_NONTHREADABLE_BLOCK;
378 582983 : goto failed_exit;
379 : }
380 :
381 7201 : if (!REG_SET_EMPTY_P (nonequal))
382 611 : goto failed_exit;
383 :
384 6590 : BITMAP_FREE (nonequal);
385 6590 : cselib_finish ();
386 6590 : if ((comparison_dominates_p (code1, code2) != 0)
387 6590 : != (XEXP (SET_SRC (set2), 1) == pc_rtx))
388 4500 : return BRANCH_EDGE (b);
389 : else
390 2090 : return FALLTHRU_EDGE (b);
391 :
392 4146731 : failed_exit:
393 4146731 : BITMAP_FREE (nonequal);
394 4146731 : cselib_finish ();
395 4146731 : return NULL;
396 : }
397 :
398 : /* Attempt to forward edges leaving basic block B.
399 : Return true if successful. */
400 :
401 : static bool
402 399362310 : try_forward_edges (int mode, basic_block b)
403 : {
404 399362310 : bool changed = false;
405 399362310 : edge_iterator ei;
406 399362310 : edge e, *threaded_edges = NULL;
407 :
408 1001319383 : for (ei = ei_start (b->succs); (e = ei_safe_edge (ei)); )
409 : {
410 601957073 : basic_block target, first;
411 601957073 : location_t goto_locus;
412 601957073 : int counter;
413 601957073 : bool threaded = false;
414 601957073 : int nthreaded_edges = 0;
415 601957073 : bool may_thread = first_pass || (b->flags & BB_MODIFIED) != 0;
416 601957073 : 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 601957073 : if (e->flags & EDGE_COMPLEX)
424 : {
425 32666416 : ei_next (&ei);
426 32666416 : continue;
427 : }
428 :
429 569290657 : target = first = e->dest;
430 569290657 : counter = NUM_FIXED_BLOCKS;
431 569290657 : goto_locus = e->goto_locus;
432 :
433 599921675 : while (counter < n_basic_blocks_for_fn (cfun))
434 : {
435 599503223 : basic_block new_target = NULL;
436 599503223 : may_thread |= (target->flags & BB_MODIFIED) != 0;
437 :
438 599503223 : if (FORWARDER_BLOCK_P (target)
439 639630210 : && single_succ (target) != EXIT_BLOCK_PTR_FOR_FN (cfun))
440 : {
441 : /* Bypass trivial infinite loops. */
442 30814470 : new_target = single_succ (target);
443 30814470 : if (target == new_target)
444 : counter = n_basic_blocks_for_fn (cfun);
445 30538762 : else if (!optimize)
446 : {
447 : /* When not optimizing, ensure that edges or forwarder
448 : blocks with different locus are not optimized out. */
449 1186648 : location_t new_locus = single_succ_edge (target)->goto_locus;
450 1186648 : location_t locus = goto_locus;
451 :
452 1186648 : if (LOCATION_LOCUS (new_locus) != UNKNOWN_LOCATION
453 473132 : && LOCATION_LOCUS (locus) != UNKNOWN_LOCATION
454 1498056 : && new_locus != locus)
455 : new_target = NULL;
456 : else
457 : {
458 1005301 : if (LOCATION_LOCUS (new_locus) != UNKNOWN_LOCATION)
459 291785 : locus = new_locus;
460 :
461 1005301 : rtx_insn *last = BB_END (target);
462 1005301 : if (DEBUG_INSN_P (last))
463 6 : last = prev_nondebug_insn (last);
464 1005301 : if (last && INSN_P (last))
465 498553 : new_locus = INSN_LOCATION (last);
466 : else
467 : new_locus = UNKNOWN_LOCATION;
468 :
469 498553 : if (LOCATION_LOCUS (new_locus) != UNKNOWN_LOCATION
470 477424 : && LOCATION_LOCUS (locus) != UNKNOWN_LOCATION
471 1368963 : && new_locus != locus)
472 : new_target = NULL;
473 : else
474 : {
475 997192 : if (LOCATION_LOCUS (new_locus) != UNKNOWN_LOCATION)
476 469315 : 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 568688753 : else if ((mode & CLEANUP_THREADING) && may_thread)
487 : {
488 28173159 : edge t = thread_jump (e, target);
489 28173159 : if (t)
490 : {
491 6590 : if (!threaded_edges)
492 6523 : 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. */
500 168 : for (i = 0; i < nthreaded_edges; ++i)
501 123 : if (threaded_edges[i] == t)
502 : break;
503 67 : if (i < nthreaded_edges)
504 : {
505 22 : counter = n_basic_blocks_for_fn (cfun);
506 22 : break;
507 : }
508 : }
509 :
510 : /* Detect an infinite loop across the start block. */
511 6568 : if (t->dest == b)
512 : break;
513 :
514 6004 : gcc_assert (nthreaded_edges
515 : < (n_basic_blocks_for_fn (cfun)
516 : - NUM_FIXED_BLOCKS));
517 6004 : threaded_edges[nthreaded_edges++] = t;
518 :
519 6004 : new_target = t->dest;
520 6004 : new_target_threaded = true;
521 : }
522 : }
523 :
524 30631018 : if (!new_target)
525 : break;
526 :
527 30631018 : counter++;
528 : /* Do not turn non-crossing jump to crossing. Depending on target
529 : it may require different instruction pattern. */
530 30631018 : if ((e->flags & EDGE_CROSSING)
531 30598731 : || BB_PARTITION (first) == BB_PARTITION (new_target))
532 : {
533 14983661 : target = new_target;
534 14983661 : threaded |= new_target_threaded;
535 : }
536 : }
537 :
538 569290657 : if (counter >= n_basic_blocks_for_fn (cfun))
539 : {
540 418474 : if (dump_file)
541 4 : fprintf (dump_file, "Infinite loop in BB %i.\n",
542 : target->index);
543 : }
544 568872183 : 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 13890557 : profile_count edge_count = e->count ();
550 13890557 : int n = 0;
551 :
552 13890557 : e->goto_locus = goto_locus;
553 :
554 : /* Don't force if target is exit block. */
555 13890557 : if (threaded && target != EXIT_BLOCK_PTR_FOR_FN (cfun))
556 : {
557 5935 : notice_new_block (redirect_edge_and_branch_force (e, target));
558 5935 : if (dump_file)
559 0 : fprintf (dump_file, "Conditionals threaded.\n");
560 : }
561 13884622 : else if (!redirect_edge_and_branch (e, target))
562 : {
563 7389737 : if (dump_file)
564 199 : fprintf (dump_file,
565 : "Forwarding edge %i->%i to %i failed.\n",
566 199 : b->index, e->dest->index, target->index);
567 7389737 : ei_next (&ei);
568 7389737 : 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 6614835 : do
575 : {
576 6614835 : edge t;
577 :
578 6614835 : if (!single_succ_p (first))
579 : {
580 5978 : gcc_assert (n < nthreaded_edges);
581 5978 : t = threaded_edges [n++];
582 5978 : gcc_assert (t->src == first);
583 5978 : update_bb_profile_for_threading (first, edge_count, t);
584 5978 : update_br_prob_note (first);
585 : }
586 : else
587 : {
588 6608857 : 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 6608857 : if (n < nthreaded_edges
594 0 : && first == threaded_edges [n]->src)
595 0 : n++;
596 6608857 : t = single_succ_edge (first);
597 : }
598 :
599 6614835 : first = t->dest;
600 : }
601 6614835 : while (first != target);
602 :
603 6500820 : changed = true;
604 6500820 : continue;
605 6500820 : }
606 555400100 : ei_next (&ei);
607 : }
608 :
609 399362310 : free (threaded_edges);
610 399362310 : 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 21085 : merge_blocks_move_predecessor_nojumps (basic_block a, basic_block b)
620 : {
621 21085 : 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 21085 : if (BB_PARTITION (a) != BB_PARTITION (b))
634 : return;
635 :
636 21085 : barrier = next_nonnote_insn (BB_END (a));
637 21085 : gcc_assert (BARRIER_P (barrier));
638 21085 : delete_insn (barrier);
639 :
640 : /* Scramble the insn chain. */
641 21085 : if (BB_END (a) != PREV_INSN (BB_HEAD (b)))
642 21058 : reorder_insns_nobb (BB_HEAD (a), BB_END (a), PREV_INSN (BB_HEAD (b)));
643 21085 : df_set_bb_dirty (a);
644 :
645 21085 : 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 21085 : unlink_block (a);
652 21085 : link_block (a, b->prev_bb);
653 :
654 : /* Now blocks A and B are contiguous. Merge them. */
655 21085 : 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 30849 : merge_blocks_move_successor_nojumps (basic_block a, basic_block b)
664 : {
665 30849 : rtx_insn *barrier, *real_b_end;
666 30849 : rtx_insn *label;
667 30849 : 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 30849 : if (BB_PARTITION (a) != BB_PARTITION (b))
680 0 : return;
681 :
682 30849 : 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 30849 : if (tablejump_p (BB_END (b), &label, &table)
687 30849 : && 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 30849 : barrier = NEXT_INSN (BB_END (b));
694 30849 : if (barrier && BARRIER_P (barrier))
695 30849 : delete_insn (barrier);
696 :
697 :
698 : /* Scramble the insn chain. */
699 30849 : reorder_insns_nobb (BB_HEAD (b), BB_END (b), BB_END (a));
700 :
701 : /* Restore the real end of b. */
702 30849 : BB_END (b) = real_b_end;
703 :
704 30849 : if (dump_file)
705 22 : 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 30849 : 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 6770032 : merge_blocks_move (edge e, basic_block b, basic_block c, int mode)
726 : {
727 6770032 : 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 6770032 : 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 6446709 : if (e->flags & EDGE_FALLTHRU)
744 : {
745 3754479 : int b_index = b->index, c_index = c->index;
746 :
747 : /* Protect the loop latches. */
748 3754479 : if (current_loops && c->loop_father->latch == c)
749 : return NULL;
750 :
751 3709597 : merge_blocks (b, c);
752 3709597 : update_forwarder_flag (b);
753 :
754 3709597 : if (dump_file)
755 823 : fprintf (dump_file, "Merged %d and %d without moving.\n",
756 : b_index, c_index);
757 :
758 4813573 : 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 2692230 : else if (mode & CLEANUP_EXPENSIVE)
764 : {
765 899702 : edge tmp_edge, b_fallthru_edge;
766 899702 : bool c_has_outgoing_fallthru;
767 899702 : 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 899702 : 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 54091 : tmp_edge = find_fallthru_edge (c->succs);
781 54091 : c_has_outgoing_fallthru = (tmp_edge != NULL);
782 :
783 54091 : tmp_edge = find_fallthru_edge (b->preds);
784 54091 : b_has_incoming_fallthru = (tmp_edge != NULL);
785 54091 : b_fallthru_edge = tmp_edge;
786 54091 : next = b->prev_bb;
787 54091 : 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 54091 : if (! c_has_outgoing_fallthru)
794 : {
795 30849 : merge_blocks_move_successor_nojumps (b, c);
796 30849 : 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 23242 : if (b_has_incoming_fallthru)
805 : {
806 21625 : basic_block bb;
807 :
808 21625 : if (b_fallthru_edge->src == ENTRY_BLOCK_PTR_FOR_FN (cfun))
809 : return NULL;
810 19468 : bb = force_nonfallthru (b_fallthru_edge);
811 19468 : if (bb)
812 14990 : notice_new_block (bb);
813 : }
814 :
815 21085 : merge_blocks_move_predecessor_nojumps (b, c);
816 21085 : 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 151249632 : merge_memattrs (rtx x, rtx y)
828 : {
829 151249632 : int i;
830 151249632 : int j;
831 151249632 : enum rtx_code code;
832 151249632 : const char *fmt;
833 :
834 151249632 : if (x == y)
835 : return;
836 112104329 : if (x == 0 || y == 0)
837 : return;
838 :
839 112064750 : code = GET_CODE (x);
840 :
841 112064750 : if (code != GET_CODE (y))
842 : return;
843 :
844 112064372 : if (GET_MODE (x) != GET_MODE (y))
845 : return;
846 :
847 112061430 : if (code == MEM && !mem_attrs_eq_p (MEM_ATTRS (x), MEM_ATTRS (y)))
848 : {
849 50361 : if (! MEM_ATTRS (x))
850 894 : MEM_ATTRS (y) = 0;
851 49467 : else if (! MEM_ATTRS (y))
852 1411 : MEM_ATTRS (x) = 0;
853 : else
854 : {
855 48056 : if (MEM_ALIAS_SET (x) != MEM_ALIAS_SET (y))
856 : {
857 2935 : set_mem_alias_set (x, 0);
858 2935 : set_mem_alias_set (y, 0);
859 : }
860 :
861 48056 : if (! mem_expr_equal_p (MEM_EXPR (x), MEM_EXPR (y)))
862 : {
863 47412 : set_mem_expr (x, 0);
864 47412 : set_mem_expr (y, 0);
865 47412 : clear_mem_offset (x);
866 47412 : clear_mem_offset (y);
867 : }
868 644 : else if (MEM_OFFSET_KNOWN_P (x) != MEM_OFFSET_KNOWN_P (y)
869 644 : || (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 56226 : if (!MEM_SIZE_KNOWN_P (x))
877 210 : clear_mem_size (y);
878 55817 : else if (!MEM_SIZE_KNOWN_P (y))
879 0 : clear_mem_size (x);
880 47846 : else if (known_le (MEM_SIZE (x), MEM_SIZE (y)))
881 47802 : 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 64406 : set_mem_align (x, MIN (MEM_ALIGN (x), MEM_ALIGN (y)));
892 56243 : set_mem_align (y, MEM_ALIGN (x));
893 : }
894 : }
895 112061430 : if (code == MEM)
896 : {
897 6495637 : if (MEM_READONLY_P (x) != MEM_READONLY_P (y))
898 : {
899 5 : MEM_READONLY_P (x) = 0;
900 5 : MEM_READONLY_P (y) = 0;
901 : }
902 6495637 : if (MEM_NOTRAP_P (x) != MEM_NOTRAP_P (y))
903 : {
904 303 : MEM_NOTRAP_P (x) = 0;
905 303 : MEM_NOTRAP_P (y) = 0;
906 : }
907 6495637 : if (MEM_VOLATILE_P (x) != MEM_VOLATILE_P (y))
908 : {
909 5 : MEM_VOLATILE_P (x) = 1;
910 5 : MEM_VOLATILE_P (y) = 1;
911 : }
912 : }
913 :
914 112061430 : fmt = GET_RTX_FORMAT (code);
915 339043930 : for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
916 : {
917 226982500 : switch (fmt[i])
918 : {
919 377436 : case 'E':
920 : /* Two vectors must have the same length. */
921 377436 : if (XVECLEN (x, i) != XVECLEN (y, i))
922 : return;
923 :
924 1114118 : for (j = 0; j < XVECLEN (x, i); j++)
925 736682 : merge_memattrs (XVECEXP (x, i, j), XVECEXP (y, i, j));
926 :
927 : break;
928 :
929 141300007 : case 'e':
930 141300007 : 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 7764442 : values_equal_p (rtx note1, rtx note2, rtx src1, rtx src2)
983 : {
984 7764442 : if (note1
985 7764442 : && note2
986 1283269 : && CONST_INT_P (XEXP (note1, 0))
987 7822333 : && rtx_equal_p (XEXP (note1, 0), XEXP (note2, 0)))
988 : return 1;
989 :
990 7764442 : if (!note1
991 7764442 : && !note2
992 6005958 : && CONST_INT_P (src1)
993 2541945 : && CONST_INT_P (src2)
994 10207422 : && rtx_equal_p (src1, src2))
995 : return 1;
996 :
997 7764442 : if (note1
998 1553799 : && CONST_INT_P (src2)
999 7909576 : && rtx_equal_p (XEXP (note1, 0), src2))
1000 : return 1;
1001 :
1002 7764442 : if (note2
1003 1487954 : && CONST_INT_P (src1)
1004 7839967 : && 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 14027544 : can_replace_by (rtx_insn *i1, rtx_insn *i2)
1017 : {
1018 14027544 : rtx s1, s2, d1, d2, src1, src2, note1, note2;
1019 14027544 : bool c1, c2;
1020 :
1021 : /* Check for 2 sets. */
1022 14027544 : s1 = single_set (i1);
1023 14027544 : s2 = single_set (i2);
1024 14027544 : if (s1 == NULL_RTX || s2 == NULL_RTX)
1025 : return dir_none;
1026 :
1027 : /* Check that the 2 sets set the same dest. */
1028 13269155 : d1 = SET_DEST (s1);
1029 13269155 : d2 = SET_DEST (s2);
1030 26538310 : if (!(reload_completed
1031 13269155 : ? 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 7764442 : note1 = find_reg_equal_equiv_note (i1);
1037 7764442 : note2 = find_reg_equal_equiv_note (i2);
1038 :
1039 7764442 : src1 = SET_SRC (s1);
1040 7764442 : src2 = SET_SRC (s2);
1041 :
1042 7764442 : 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 24303338 : 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 16576167 : if (a == dir_both)
1083 : return b;
1084 4013084 : 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 687051 : insns_have_identical_cfa_notes (rtx_insn *i1, rtx_insn *i2)
1107 : {
1108 687051 : rtx n1, n2;
1109 687051 : for (n1 = REG_NOTES (i1), n2 = REG_NOTES (i2); ;
1110 550295 : n1 = XEXP (n1, 1), n2 = XEXP (n2, 1))
1111 : {
1112 : /* Skip over reg notes not related to CFI information. */
1113 1814879 : while (n1 && !reg_note_cfa_p[REG_NOTE_KIND (n1)])
1114 27238 : n1 = XEXP (n1, 1);
1115 1264333 : while (n2 && !reg_note_cfa_p[REG_NOTE_KIND (n2)])
1116 26987 : n2 = XEXP (n2, 1);
1117 1237346 : if (n1 == NULL_RTX && n2 == NULL_RTX)
1118 : return true;
1119 668862 : if (n1 == NULL_RTX || n2 == NULL_RTX)
1120 : return false;
1121 662266 : if (XEXP (n1, 0) == XEXP (n2, 0))
1122 : ;
1123 662260 : else if (XEXP (n1, 0) == NULL_RTX || XEXP (n2, 0) == NULL_RTX)
1124 : return false;
1125 1324520 : else if (!(reload_completed
1126 662260 : ? 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 40678355 : old_insns_match_p (int mode ATTRIBUTE_UNUSED, rtx_insn *i1, rtx_insn *i2)
1139 : {
1140 40678355 : rtx p1, p2;
1141 :
1142 : /* Verify that I1 and I2 are equivalent. */
1143 40678355 : 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 35118355 : 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 35038673 : p1 = find_reg_note (i1, REG_ARGS_SIZE, NULL);
1153 35038673 : p2 = find_reg_note (i2, REG_ARGS_SIZE, NULL);
1154 35038673 : if (p1 && p2)
1155 : {
1156 3768293 : p1 = XEXP (p1, 0);
1157 3768293 : p2 = XEXP (p2, 0);
1158 3768293 : 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 3667276 : if (!frame_pointer_needed
1164 3667276 : && known_eq (find_args_size_adjust (i1), HOST_WIDE_INT_MIN))
1165 22 : return dir_none;
1166 : }
1167 31270380 : else if (p1 || p2)
1168 : return dir_none;
1169 :
1170 : /* Do not allow cross-jumping between frame related insns and other
1171 : insns. */
1172 33374424 : if (RTX_FRAME_RELATED_P (i1) != RTX_FRAME_RELATED_P (i2))
1173 : return dir_none;
1174 :
1175 32766996 : p1 = PATTERN (i1);
1176 32766996 : p2 = PATTERN (i2);
1177 :
1178 32766996 : 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 30400942 : if (CALL_P (i1))
1194 : {
1195 : /* Ensure the same EH region. */
1196 11543945 : rtx n1 = find_reg_note (i1, REG_EH_REGION, 0);
1197 11543945 : rtx n2 = find_reg_note (i2, REG_EH_REGION, 0);
1198 :
1199 11543945 : if (!n1 && n2)
1200 : return dir_none;
1201 :
1202 11459432 : if (n1 && (!n2 || XEXP (n1, 0) != XEXP (n2, 0)))
1203 : return dir_none;
1204 :
1205 10688343 : if (!rtx_equal_p (CALL_INSN_FUNCTION_USAGE (i1),
1206 10688343 : CALL_INSN_FUNCTION_USAGE (i2))
1207 10688343 : || SIBLING_CALL_P (i1) != SIBLING_CALL_P (i2))
1208 : return dir_none;
1209 :
1210 : /* For address sanitizer, never crossjump __asan_report_* builtins,
1211 : otherwise errors might be reported on incorrect lines. */
1212 7082886 : if (flag_sanitize & SANITIZE_ADDRESS)
1213 : {
1214 298684 : rtx call = get_call_rtx_from (i1);
1215 298684 : if (call && GET_CODE (XEXP (XEXP (call, 0), 0)) == SYMBOL_REF)
1216 : {
1217 298684 : rtx symbol = XEXP (XEXP (call, 0), 0);
1218 298684 : if (SYMBOL_REF_DECL (symbol)
1219 298684 : && TREE_CODE (SYMBOL_REF_DECL (symbol)) == FUNCTION_DECL)
1220 : {
1221 298684 : if ((DECL_BUILT_IN_CLASS (SYMBOL_REF_DECL (symbol))
1222 298684 : == BUILT_IN_NORMAL)
1223 296719 : && DECL_FUNCTION_CODE (SYMBOL_REF_DECL (symbol))
1224 : >= BUILT_IN_ASAN_REPORT_LOAD1
1225 593881 : && DECL_FUNCTION_CODE (SYMBOL_REF_DECL (symbol))
1226 : <= BUILT_IN_ASAN_STOREN)
1227 : return dir_none;
1228 : }
1229 : }
1230 : }
1231 :
1232 6788628 : if (insn_callee_abi (i1) != insn_callee_abi (i2))
1233 : return dir_none;
1234 : }
1235 :
1236 : /* If both i1 and i2 are frame related, verify all the CFA notes
1237 : in the same order and with the same content. */
1238 25589331 : if (RTX_FRAME_RELATED_P (i1) && !insns_have_identical_cfa_notes (i1, i2))
1239 : return dir_none;
1240 :
1241 : #ifdef STACK_REGS
1242 : /* If cross_jump_death_matters is not 0, the insn's mode
1243 : indicates whether or not the insn contains any stack-like
1244 : regs. */
1245 :
1246 25470764 : if ((mode & CLEANUP_POST_REGSTACK) && stack_regs_mentioned (i1))
1247 : {
1248 : /* If register stack conversion has already been done, then
1249 : death notes must also be compared before it is certain that
1250 : the two instruction streams match. */
1251 :
1252 : rtx note;
1253 : HARD_REG_SET i1_regset, i2_regset;
1254 :
1255 0 : CLEAR_HARD_REG_SET (i1_regset);
1256 0 : CLEAR_HARD_REG_SET (i2_regset);
1257 :
1258 0 : for (note = REG_NOTES (i1); note; note = XEXP (note, 1))
1259 0 : if (REG_NOTE_KIND (note) == REG_DEAD && STACK_REG_P (XEXP (note, 0)))
1260 0 : SET_HARD_REG_BIT (i1_regset, REGNO (XEXP (note, 0)));
1261 :
1262 0 : for (note = REG_NOTES (i2); note; note = XEXP (note, 1))
1263 0 : if (REG_NOTE_KIND (note) == REG_DEAD && STACK_REG_P (XEXP (note, 0)))
1264 0 : SET_HARD_REG_BIT (i2_regset, REGNO (XEXP (note, 0)));
1265 :
1266 0 : if (i1_regset != i2_regset)
1267 0 : return dir_none;
1268 : }
1269 : #endif
1270 :
1271 25470764 : if (reload_completed
1272 25470764 : ? rtx_renumbered_equal_p (p1, p2) : rtx_equal_p (p1, p2))
1273 : return dir_both;
1274 :
1275 14027544 : return can_replace_by (i1, i2);
1276 : }
1277 :
1278 : /* When comparing insns I1 and I2 in flow_find_cross_jump or
1279 : flow_find_head_matching_sequence, ensure the notes match. */
1280 :
1281 : static void
1282 9212943 : merge_notes (rtx_insn *i1, rtx_insn *i2)
1283 : {
1284 : /* If the merged insns have different REG_EQUAL notes, then
1285 : remove them. */
1286 9212943 : rtx equiv1 = find_reg_equal_equiv_note (i1);
1287 9212943 : rtx equiv2 = find_reg_equal_equiv_note (i2);
1288 :
1289 9212943 : if (equiv1 && !equiv2)
1290 24152 : remove_note (i1, equiv1);
1291 9188791 : else if (!equiv1 && equiv2)
1292 7605 : remove_note (i2, equiv2);
1293 9181186 : else if (equiv1 && equiv2
1294 9181186 : && !rtx_equal_p (XEXP (equiv1, 0), XEXP (equiv2, 0)))
1295 : {
1296 547 : remove_note (i1, equiv1);
1297 547 : remove_note (i2, equiv2);
1298 : }
1299 9212943 : }
1300 :
1301 : /* Walks from I1 in BB1 backward till the next non-debug insn, and returns the
1302 : resulting insn in I1, and the corresponding bb in BB1. At the head of a
1303 : bb, if there is a predecessor bb that reaches this bb via fallthru, and
1304 : FOLLOW_FALLTHRU, walks further in the predecessor bb and registers this in
1305 : DID_FALLTHRU. Otherwise, stops at the head of the bb. */
1306 :
1307 : static void
1308 50352168 : walk_to_nondebug_insn (rtx_insn **i1, basic_block *bb1, bool follow_fallthru,
1309 : bool *did_fallthru)
1310 : {
1311 50352168 : edge fallthru;
1312 :
1313 50352168 : *did_fallthru = false;
1314 :
1315 : /* Ignore notes. */
1316 69294531 : while (!NONDEBUG_INSN_P (*i1))
1317 : {
1318 20186724 : if (*i1 != BB_HEAD (*bb1))
1319 : {
1320 18716691 : *i1 = PREV_INSN (*i1);
1321 18716691 : continue;
1322 : }
1323 :
1324 1470033 : if (!follow_fallthru)
1325 : return;
1326 :
1327 1291929 : fallthru = find_fallthru_edge ((*bb1)->preds);
1328 583665 : if (!fallthru || fallthru->src == ENTRY_BLOCK_PTR_FOR_FN (cfun)
1329 1875532 : || !single_succ_p (fallthru->src))
1330 : return;
1331 :
1332 225672 : *bb1 = fallthru->src;
1333 225672 : *i1 = BB_END (*bb1);
1334 225672 : *did_fallthru = true;
1335 : }
1336 : }
1337 :
1338 : /* Look through the insns at the end of BB1 and BB2 and find the longest
1339 : sequence that are either equivalent, or allow forward or backward
1340 : replacement. Store the first insns for that sequence in *F1 and *F2 and
1341 : return the sequence length.
1342 :
1343 : DIR_P indicates the allowed replacement direction on function entry, and
1344 : the actual replacement direction on function exit. If NULL, only equivalent
1345 : sequences are allowed.
1346 :
1347 : To simplify callers of this function, if the blocks match exactly,
1348 : store the head of the blocks in *F1 and *F2. */
1349 :
1350 : int
1351 16172620 : flow_find_cross_jump (basic_block bb1, basic_block bb2, rtx_insn **f1,
1352 : rtx_insn **f2, enum replace_direction *dir_p)
1353 : {
1354 16172620 : rtx_insn *i1, *i2, *last1, *last2, *afterlast1, *afterlast2;
1355 16172620 : int ninsns = 0;
1356 16172620 : enum replace_direction dir, last_dir, afterlast_dir;
1357 16172620 : bool follow_fallthru, did_fallthru;
1358 :
1359 16172620 : if (dir_p)
1360 16172620 : dir = *dir_p;
1361 : else
1362 : dir = dir_both;
1363 16172620 : afterlast_dir = dir;
1364 16172620 : last_dir = afterlast_dir;
1365 :
1366 : /* Skip simple jumps at the end of the blocks. Complex jumps still
1367 : need to be compared for equivalence, which we'll do below. */
1368 :
1369 16172620 : i1 = BB_END (bb1);
1370 16172620 : last1 = afterlast1 = last2 = afterlast2 = NULL;
1371 16172620 : if (onlyjump_p (i1)
1372 16172620 : || (returnjump_p (i1) && !side_effects_p (PATTERN (i1))))
1373 : {
1374 14604038 : last1 = i1;
1375 14604038 : i1 = PREV_INSN (i1);
1376 : }
1377 :
1378 16172620 : i2 = BB_END (bb2);
1379 16172620 : if (onlyjump_p (i2)
1380 16172620 : || (returnjump_p (i2) && !side_effects_p (PATTERN (i2))))
1381 : {
1382 11827116 : last2 = i2;
1383 : /* Count everything except for unconditional jump as insn.
1384 : Don't count any jumps if dir_p is NULL. */
1385 11827116 : if (!simplejump_p (i2) && !returnjump_p (i2) && last1 && dir_p)
1386 : ninsns++;
1387 11827116 : i2 = PREV_INSN (i2);
1388 : }
1389 :
1390 34179548 : while (true)
1391 : {
1392 : /* In the following example, we can replace all jumps to C by jumps to A.
1393 :
1394 : This removes 4 duplicate insns.
1395 : [bb A] insn1 [bb C] insn1
1396 : insn2 insn2
1397 : [bb B] insn3 insn3
1398 : insn4 insn4
1399 : jump_insn jump_insn
1400 :
1401 : We could also replace all jumps to A by jumps to C, but that leaves B
1402 : alive, and removes only 2 duplicate insns. In a subsequent crossjump
1403 : step, all jumps to B would be replaced with jumps to the middle of C,
1404 : achieving the same result with more effort.
1405 : So we allow only the first possibility, which means that we don't allow
1406 : fallthru in the block that's being replaced. */
1407 :
1408 25176084 : follow_fallthru = dir_p && dir != dir_forward;
1409 25176084 : walk_to_nondebug_insn (&i1, &bb1, follow_fallthru, &did_fallthru);
1410 25176084 : if (did_fallthru)
1411 24913 : dir = dir_backward;
1412 :
1413 25176084 : follow_fallthru = dir_p && dir != dir_backward;
1414 25176084 : walk_to_nondebug_insn (&i2, &bb2, follow_fallthru, &did_fallthru);
1415 25176084 : if (did_fallthru)
1416 200749 : dir = dir_forward;
1417 :
1418 25176084 : if (i1 == BB_HEAD (bb1) || i2 == BB_HEAD (bb2))
1419 : break;
1420 :
1421 : /* Do not turn corssing edge to non-crossing or vice versa after
1422 : reload. */
1423 24303338 : if (BB_PARTITION (BLOCK_FOR_INSN (i1))
1424 24303338 : != BB_PARTITION (BLOCK_FOR_INSN (i2))
1425 24303338 : && reload_completed)
1426 : break;
1427 :
1428 24303338 : dir = merge_dir (dir, old_insns_match_p (0, i1, i2));
1429 21566547 : if (dir == dir_none || (!dir_p && dir != dir_both))
1430 : break;
1431 :
1432 9003464 : merge_memattrs (i1, i2);
1433 :
1434 : /* Don't begin a cross-jump with a NOTE insn. */
1435 9003464 : if (INSN_P (i1))
1436 : {
1437 9003464 : merge_notes (i1, i2);
1438 :
1439 9003464 : afterlast1 = last1, afterlast2 = last2;
1440 9003464 : last1 = i1, last2 = i2;
1441 9003464 : afterlast_dir = last_dir;
1442 9003464 : last_dir = dir;
1443 9003464 : if (active_insn_p (i1))
1444 8896752 : ninsns++;
1445 : }
1446 :
1447 9003464 : i1 = PREV_INSN (i1);
1448 9003464 : i2 = PREV_INSN (i2);
1449 : }
1450 :
1451 : /* Include preceding notes and labels in the cross-jump. One,
1452 : this may bring us to the head of the blocks as requested above.
1453 : Two, it keeps line number notes as matched as may be. */
1454 16172620 : if (ninsns)
1455 : {
1456 5385292 : bb1 = BLOCK_FOR_INSN (last1);
1457 13696805 : while (last1 != BB_HEAD (bb1) && !NONDEBUG_INSN_P (PREV_INSN (last1)))
1458 : last1 = PREV_INSN (last1);
1459 :
1460 10489694 : if (last1 != BB_HEAD (bb1) && LABEL_P (PREV_INSN (last1)))
1461 : last1 = PREV_INSN (last1);
1462 :
1463 5385292 : bb2 = BLOCK_FOR_INSN (last2);
1464 13726546 : while (last2 != BB_HEAD (bb2) && !NONDEBUG_INSN_P (PREV_INSN (last2)))
1465 : last2 = PREV_INSN (last2);
1466 :
1467 10068736 : if (last2 != BB_HEAD (bb2) && LABEL_P (PREV_INSN (last2)))
1468 : last2 = PREV_INSN (last2);
1469 :
1470 5385292 : *f1 = last1;
1471 5385292 : *f2 = last2;
1472 : }
1473 :
1474 16172620 : if (dir_p)
1475 16172620 : *dir_p = last_dir;
1476 16172620 : return ninsns;
1477 : }
1478 :
1479 : /* Like flow_find_cross_jump, except start looking for a matching sequence from
1480 : the head of the two blocks. Do not include jumps at the end.
1481 : If STOP_AFTER is nonzero, stop after finding that many matching
1482 : instructions. If STOP_AFTER is zero, count all INSN_P insns, if it is
1483 : non-zero, only count active insns. */
1484 :
1485 : int
1486 4662594 : flow_find_head_matching_sequence (basic_block bb1, basic_block bb2, rtx_insn **f1,
1487 : rtx_insn **f2, int stop_after)
1488 : {
1489 4662594 : rtx_insn *i1, *i2, *last1, *last2, *beforelast1, *beforelast2;
1490 4662594 : int ninsns = 0;
1491 4662594 : edge e;
1492 4662594 : edge_iterator ei;
1493 4662594 : int nehedges1 = 0, nehedges2 = 0;
1494 :
1495 11198838 : FOR_EACH_EDGE (e, ei, bb1->succs)
1496 6536244 : if (e->flags & EDGE_EH)
1497 305521 : nehedges1++;
1498 11515182 : FOR_EACH_EDGE (e, ei, bb2->succs)
1499 6852588 : if (e->flags & EDGE_EH)
1500 353975 : nehedges2++;
1501 :
1502 4662594 : i1 = BB_HEAD (bb1);
1503 4662594 : i2 = BB_HEAD (bb2);
1504 4662594 : last1 = beforelast1 = last2 = beforelast2 = NULL;
1505 :
1506 195124 : while (true)
1507 : {
1508 : /* Ignore notes, except NOTE_INSN_EPILOGUE_BEG. */
1509 21775423 : while (!NONDEBUG_INSN_P (i1) && i1 != BB_END (bb1))
1510 : {
1511 16741901 : if (NOTE_P (i1) && NOTE_KIND (i1) == NOTE_INSN_EPILOGUE_BEG)
1512 : break;
1513 16722581 : i1 = NEXT_INSN (i1);
1514 : }
1515 :
1516 21525641 : while (!NONDEBUG_INSN_P (i2) && i2 != BB_END (bb2))
1517 : {
1518 16705839 : if (NOTE_P (i2) && NOTE_KIND (i2) == NOTE_INSN_EPILOGUE_BEG)
1519 : break;
1520 16667923 : i2 = NEXT_INSN (i2);
1521 : }
1522 :
1523 4857718 : if ((i1 == BB_END (bb1) && !NONDEBUG_INSN_P (i1))
1524 4845311 : || (i2 == BB_END (bb2) && !NONDEBUG_INSN_P (i2)))
1525 : break;
1526 :
1527 4840158 : if (NOTE_P (i1) || NOTE_P (i2)
1528 4784814 : || JUMP_P (i1) || JUMP_P (i2))
1529 : break;
1530 :
1531 : /* A sanity check to make sure we're not merging insns with different
1532 : effects on EH. If only one of them ends a basic block, it shouldn't
1533 : have an EH edge; if both end a basic block, there should be the same
1534 : number of EH edges. */
1535 3931709 : if ((i1 == BB_END (bb1) && i2 != BB_END (bb2)
1536 222993 : && nehedges1 > 0)
1537 3896072 : || (i2 == BB_END (bb2) && i1 != BB_END (bb1)
1538 240241 : && nehedges2 > 0)
1539 3867172 : || (i1 == BB_END (bb1) && i2 == BB_END (bb2)
1540 26887 : && nehedges1 != nehedges2))
1541 : break;
1542 :
1543 3863800 : if (old_insns_match_p (0, i1, i2) != dir_both)
1544 : break;
1545 :
1546 209479 : merge_memattrs (i1, i2);
1547 :
1548 : /* Don't begin a cross-jump with a NOTE insn. */
1549 209479 : if (INSN_P (i1))
1550 : {
1551 209479 : merge_notes (i1, i2);
1552 :
1553 209479 : beforelast1 = last1, beforelast2 = last2;
1554 209479 : last1 = i1, last2 = i2;
1555 209479 : if (!stop_after || active_insn_p (i1))
1556 209479 : ninsns++;
1557 : }
1558 :
1559 209479 : if (i1 == BB_END (bb1) || i2 == BB_END (bb2)
1560 195124 : || (stop_after > 0 && ninsns == stop_after))
1561 : break;
1562 :
1563 195124 : i1 = NEXT_INSN (i1);
1564 195124 : i2 = NEXT_INSN (i2);
1565 : }
1566 :
1567 4662594 : if (ninsns)
1568 : {
1569 117183 : *f1 = last1;
1570 117183 : *f2 = last2;
1571 : }
1572 :
1573 4662594 : return ninsns;
1574 : }
1575 :
1576 : /* Return true iff outgoing edges of BB1 and BB2 match, together with
1577 : the branch instruction. This means that if we commonize the control
1578 : flow before end of the basic block, the semantic remains unchanged.
1579 :
1580 : We may assume that there exists one edge with a common destination. */
1581 :
1582 : static bool
1583 47186376 : outgoing_edges_match (int mode, basic_block bb1, basic_block bb2)
1584 : {
1585 47186376 : int nehedges1 = 0, nehedges2 = 0;
1586 47186376 : edge fallthru1 = 0, fallthru2 = 0;
1587 47186376 : edge e1, e2;
1588 47186376 : edge_iterator ei;
1589 :
1590 : /* If we performed shrink-wrapping, edges to the exit block can
1591 : only be distinguished for JUMP_INSNs. The two paths may differ in
1592 : whether they went through the prologue. Sibcalls are fine, we know
1593 : that we either didn't need or inserted an epilogue before them. */
1594 47186376 : if (crtl->shrink_wrapped
1595 1204821 : && single_succ_p (bb1)
1596 465879 : && single_succ (bb1) == EXIT_BLOCK_PTR_FOR_FN (cfun)
1597 148909 : && (!JUMP_P (BB_END (bb1))
1598 : /* Punt if the only successor is a fake edge to exit, the jump
1599 : must be some weird one. */
1600 64835 : || (single_succ_edge (bb1)->flags & EDGE_FAKE) != 0)
1601 47270530 : && !(CALL_P (BB_END (bb1)) && SIBLING_CALL_P (BB_END (bb1))))
1602 : return false;
1603 :
1604 : /* If BB1 has only one successor, we may be looking at either an
1605 : unconditional jump, or a fake edge to exit. */
1606 47137194 : if (single_succ_p (bb1)
1607 19346503 : && (single_succ_edge (bb1)->flags & (EDGE_COMPLEX | EDGE_FAKE)) == 0
1608 63095387 : && (!JUMP_P (BB_END (bb1)) || simplejump_p (BB_END (bb1))))
1609 15690107 : return (single_succ_p (bb2)
1610 14217048 : && (single_succ_edge (bb2)->flags
1611 14217048 : & (EDGE_COMPLEX | EDGE_FAKE)) == 0
1612 29850139 : && (!JUMP_P (BB_END (bb2)) || simplejump_p (BB_END (bb2))));
1613 :
1614 : /* Match conditional jumps - this may get tricky when fallthru and branch
1615 : edges are crossed. */
1616 31447087 : if (EDGE_COUNT (bb1->succs) == 2
1617 27706410 : && any_condjump_p (BB_END (bb1))
1618 50377761 : && onlyjump_p (BB_END (bb1)))
1619 : {
1620 18930674 : edge b1, f1, b2, f2;
1621 18930674 : bool reverse, match;
1622 18930674 : rtx set1, set2, cond1, cond2;
1623 18930674 : enum rtx_code code1, code2;
1624 :
1625 18930674 : if (EDGE_COUNT (bb2->succs) != 2
1626 8677318 : || !any_condjump_p (BB_END (bb2))
1627 27576798 : || !onlyjump_p (BB_END (bb2)))
1628 10284550 : return false;
1629 :
1630 8646124 : b1 = BRANCH_EDGE (bb1);
1631 8646124 : b2 = BRANCH_EDGE (bb2);
1632 8646124 : f1 = FALLTHRU_EDGE (bb1);
1633 8646124 : f2 = FALLTHRU_EDGE (bb2);
1634 :
1635 : /* Get around possible forwarders on fallthru edges. Other cases
1636 : should be optimized out already. */
1637 8646124 : if (FORWARDER_BLOCK_P (f1->dest))
1638 3496780 : f1 = single_succ_edge (f1->dest);
1639 :
1640 8646124 : if (FORWARDER_BLOCK_P (f2->dest))
1641 2596484 : f2 = single_succ_edge (f2->dest);
1642 :
1643 : /* To simplify use of this function, return false if there are
1644 : unneeded forwarder blocks. These will get eliminated later
1645 : during cleanup_cfg. */
1646 8646124 : if (FORWARDER_BLOCK_P (f1->dest)
1647 8641268 : || FORWARDER_BLOCK_P (f2->dest)
1648 8635756 : || FORWARDER_BLOCK_P (b1->dest)
1649 8606164 : || FORWARDER_BLOCK_P (b2->dest))
1650 : return false;
1651 :
1652 8579189 : if (f1->dest == f2->dest && b1->dest == b2->dest)
1653 : reverse = false;
1654 8381769 : else if (f1->dest == b2->dest && b1->dest == f2->dest)
1655 : reverse = true;
1656 : else
1657 : return false;
1658 :
1659 317415 : set1 = pc_set (BB_END (bb1));
1660 317415 : set2 = pc_set (BB_END (bb2));
1661 317415 : if ((XEXP (SET_SRC (set1), 1) == pc_rtx)
1662 317415 : != (XEXP (SET_SRC (set2), 1) == pc_rtx))
1663 0 : reverse = !reverse;
1664 :
1665 317415 : cond1 = XEXP (SET_SRC (set1), 0);
1666 317415 : cond2 = XEXP (SET_SRC (set2), 0);
1667 317415 : code1 = GET_CODE (cond1);
1668 317415 : if (reverse)
1669 119995 : code2 = reversed_comparison_code (cond2, BB_END (bb2));
1670 : else
1671 197420 : code2 = GET_CODE (cond2);
1672 :
1673 317415 : if (code2 == UNKNOWN)
1674 : return false;
1675 :
1676 : /* Verify codes and operands match. */
1677 899055 : match = ((code1 == code2
1678 271400 : && rtx_renumbered_equal_p (XEXP (cond1, 0), XEXP (cond2, 0))
1679 269285 : && rtx_renumbered_equal_p (XEXP (cond1, 1), XEXP (cond2, 1)))
1680 319530 : || (code1 == swap_condition (code2)
1681 4699 : && rtx_renumbered_equal_p (XEXP (cond1, 1),
1682 4699 : XEXP (cond2, 0))
1683 0 : && rtx_renumbered_equal_p (XEXP (cond1, 0),
1684 0 : XEXP (cond2, 1))));
1685 :
1686 : /* If we return true, we will join the blocks. Which means that
1687 : we will only have one branch prediction bit to work with. Thus
1688 : we require the existing branches to have probabilities that are
1689 : roughly similar. */
1690 269285 : if (match
1691 269285 : && optimize_bb_for_speed_p (bb1)
1692 244016 : && optimize_bb_for_speed_p (bb2))
1693 : {
1694 233286 : profile_probability prob2;
1695 :
1696 233286 : if (b1->dest == b2->dest)
1697 150037 : prob2 = b2->probability;
1698 : else
1699 : /* Do not use f2 probability as f2 may be forwarded. */
1700 83249 : prob2 = b2->probability.invert ();
1701 :
1702 : /* Fail if the difference in probabilities is greater than 50%.
1703 : This rules out two well-predicted branches with opposite
1704 : outcomes. */
1705 233286 : if (b1->probability.differs_lot_from_p (prob2))
1706 : {
1707 5060 : if (dump_file)
1708 : {
1709 0 : fprintf (dump_file,
1710 : "Outcomes of branch in bb %i and %i differ too"
1711 : " much (", bb1->index, bb2->index);
1712 0 : b1->probability.dump (dump_file);
1713 0 : prob2.dump (dump_file);
1714 0 : fprintf (dump_file, ")\n");
1715 : }
1716 5060 : return false;
1717 : }
1718 : }
1719 :
1720 312355 : if (dump_file && match)
1721 16 : fprintf (dump_file, "Conditionals in bb %i and %i match.\n",
1722 : bb1->index, bb2->index);
1723 :
1724 312355 : return match;
1725 : }
1726 :
1727 : /* Generic case - we are seeing a computed jump, table jump or trapping
1728 : instruction. */
1729 :
1730 : /* Check whether there are tablejumps in the end of BB1 and BB2.
1731 : Return true if they are identical. */
1732 12516413 : {
1733 12516413 : rtx_insn *label1, *label2;
1734 12516413 : rtx_jump_table_data *table1, *table2;
1735 :
1736 12516413 : if (tablejump_p (BB_END (bb1), &label1, &table1)
1737 81754 : && tablejump_p (BB_END (bb2), &label2, &table2)
1738 12522575 : && GET_CODE (PATTERN (table1)) == GET_CODE (PATTERN (table2)))
1739 : {
1740 : /* The labels should never be the same rtx. If they really are same
1741 : the jump tables are same too. So disable crossjumping of blocks BB1
1742 : and BB2 because when deleting the common insns in the end of BB1
1743 : by delete_basic_block () the jump table would be deleted too. */
1744 : /* If LABEL2 is referenced in BB1->END do not do anything
1745 : because we would loose information when replacing
1746 : LABEL1 by LABEL2 and then LABEL2 by LABEL1 in BB1->END. */
1747 6162 : if (label1 != label2 && !rtx_referenced_p (label2, BB_END (bb1)))
1748 : {
1749 : /* Set IDENTICAL to true when the tables are identical. */
1750 6162 : bool identical = false;
1751 6162 : rtx p1, p2;
1752 :
1753 6162 : p1 = PATTERN (table1);
1754 6162 : p2 = PATTERN (table2);
1755 6162 : if (GET_CODE (p1) == ADDR_VEC && rtx_equal_p (p1, p2))
1756 : {
1757 : identical = true;
1758 : }
1759 5202 : else if (GET_CODE (p1) == ADDR_DIFF_VEC
1760 202 : && (XVECLEN (p1, 1) == XVECLEN (p2, 1))
1761 95 : && rtx_equal_p (XEXP (p1, 2), XEXP (p2, 2))
1762 5297 : && rtx_equal_p (XEXP (p1, 3), XEXP (p2, 3)))
1763 : {
1764 95 : int i;
1765 :
1766 95 : identical = true;
1767 394 : for (i = XVECLEN (p1, 1) - 1; i >= 0 && identical; i--)
1768 299 : if (!rtx_equal_p (XVECEXP (p1, 1, i), XVECEXP (p2, 1, i)))
1769 : identical = false;
1770 : }
1771 :
1772 95 : if (identical)
1773 : {
1774 966 : bool match;
1775 :
1776 : /* Temporarily replace references to LABEL1 with LABEL2
1777 : in BB1->END so that we could compare the instructions. */
1778 966 : replace_label_in_insn (BB_END (bb1), label1, label2, false);
1779 :
1780 966 : match = (old_insns_match_p (mode, BB_END (bb1), BB_END (bb2))
1781 : == dir_both);
1782 966 : if (dump_file && match)
1783 0 : fprintf (dump_file,
1784 : "Tablejumps in bb %i and %i match.\n",
1785 : bb1->index, bb2->index);
1786 :
1787 : /* Set the original label in BB1->END because when deleting
1788 : a block whose end is a tablejump, the tablejump referenced
1789 : from the instruction is deleted too. */
1790 966 : replace_label_in_insn (BB_END (bb1), label2, label1, false);
1791 :
1792 6162 : return match;
1793 : }
1794 : }
1795 5196 : return false;
1796 : }
1797 : }
1798 :
1799 : /* Find the last non-debug non-note instruction in each bb, except
1800 : stop when we see the NOTE_INSN_BASIC_BLOCK, as old_insns_match_p
1801 : handles that case specially. old_insns_match_p does not handle
1802 : other types of instruction notes. */
1803 12510251 : rtx_insn *last1 = BB_END (bb1);
1804 12510251 : rtx_insn *last2 = BB_END (bb2);
1805 12510342 : while (!NOTE_INSN_BASIC_BLOCK_P (last1) &&
1806 12390970 : (DEBUG_INSN_P (last1) || NOTE_P (last1)))
1807 91 : last1 = PREV_INSN (last1);
1808 12540638 : while (!NOTE_INSN_BASIC_BLOCK_P (last2) &&
1809 12423222 : (DEBUG_INSN_P (last2) || NOTE_P (last2)))
1810 30387 : last2 = PREV_INSN (last2);
1811 12510251 : gcc_assert (last1 && last2);
1812 :
1813 : /* First ensure that the instructions match. There may be many outgoing
1814 : edges so this test is generally cheaper. */
1815 12510251 : if (old_insns_match_p (mode, last1, last2) != dir_both)
1816 : return false;
1817 :
1818 : /* Search the outgoing edges, ensure that the counts do match, find possible
1819 : fallthru and exception handling edges since these needs more
1820 : validation. */
1821 6926988 : if (EDGE_COUNT (bb1->succs) != EDGE_COUNT (bb2->succs))
1822 : return false;
1823 :
1824 2308983 : bool nonfakeedges = false;
1825 5672423 : FOR_EACH_EDGE (e1, ei, bb1->succs)
1826 : {
1827 3363440 : e2 = EDGE_SUCC (bb2, ei.index);
1828 :
1829 3363440 : if ((e1->flags & EDGE_FAKE) == 0)
1830 2450794 : nonfakeedges = true;
1831 :
1832 3363440 : if (e1->flags & EDGE_EH)
1833 1090440 : nehedges1++;
1834 :
1835 3363440 : if (e2->flags & EDGE_EH)
1836 1090440 : nehedges2++;
1837 :
1838 3363440 : if (e1->flags & EDGE_FALLTHRU)
1839 1141244 : fallthru1 = e1;
1840 3363440 : if (e2->flags & EDGE_FALLTHRU)
1841 1141244 : fallthru2 = e2;
1842 : }
1843 :
1844 : /* If number of edges of various types does not match, fail. */
1845 2308983 : if (nehedges1 != nehedges2
1846 2308983 : || (fallthru1 != 0) != (fallthru2 != 0))
1847 : return false;
1848 :
1849 : /* If !ACCUMULATE_OUTGOING_ARGS, bb1 (and bb2) have no successors
1850 : and the last real insn doesn't have REG_ARGS_SIZE note, don't
1851 : attempt to optimize, as the two basic blocks might have different
1852 : REG_ARGS_SIZE depths. For noreturn calls and unconditional
1853 : traps there should be REG_ARG_SIZE notes, they could be missing
1854 : for __builtin_unreachable () uses though. */
1855 2308983 : if (!nonfakeedges
1856 912646 : && !ACCUMULATE_OUTGOING_ARGS
1857 3221622 : && (!INSN_P (last1)
1858 912639 : || !find_reg_note (last1, REG_ARGS_SIZE, NULL)))
1859 11 : return false;
1860 :
1861 : /* fallthru edges must be forwarded to the same destination. */
1862 2308972 : if (fallthru1)
1863 : {
1864 1141244 : basic_block d1 = (FORWARDER_BLOCK_P (fallthru1->dest)
1865 1141244 : ? single_succ (fallthru1->dest) : fallthru1->dest);
1866 1141244 : basic_block d2 = (FORWARDER_BLOCK_P (fallthru2->dest)
1867 1141244 : ? single_succ (fallthru2->dest) : fallthru2->dest);
1868 :
1869 1141244 : if (d1 != d2)
1870 : return false;
1871 : }
1872 :
1873 : /* Ensure the same EH region. */
1874 1747431 : {
1875 1747431 : rtx n1 = find_reg_note (last1, REG_EH_REGION, 0);
1876 1747431 : rtx n2 = find_reg_note (last2, REG_EH_REGION, 0);
1877 :
1878 1747431 : if (!n1 && n2)
1879 : return false;
1880 :
1881 1747431 : if (n1 && (!n2 || XEXP (n1, 0) != XEXP (n2, 0)))
1882 : return false;
1883 : }
1884 :
1885 : /* The same checks as in try_crossjump_to_edge. It is required for RTL
1886 : version of sequence abstraction. */
1887 3987136 : FOR_EACH_EDGE (e1, ei, bb2->succs)
1888 : {
1889 2239735 : edge e2;
1890 2239735 : edge_iterator ei;
1891 2239735 : basic_block d1 = e1->dest;
1892 :
1893 2239735 : if (FORWARDER_BLOCK_P (d1))
1894 591477 : d1 = EDGE_SUCC (d1, 0)->dest;
1895 :
1896 2733509 : FOR_EACH_EDGE (e2, ei, bb1->succs)
1897 : {
1898 2733509 : basic_block d2 = e2->dest;
1899 2733509 : if (FORWARDER_BLOCK_P (d2))
1900 767517 : d2 = EDGE_SUCC (d2, 0)->dest;
1901 2733509 : if (d1 == d2)
1902 : break;
1903 : }
1904 :
1905 2239735 : if (!e2)
1906 0 : return false;
1907 : }
1908 :
1909 : return true;
1910 : }
1911 :
1912 : /* Returns true if BB basic block has a preserve label. */
1913 :
1914 : static bool
1915 365568 : block_has_preserve_label (basic_block bb)
1916 : {
1917 365568 : return (bb
1918 365568 : && block_label (bb)
1919 680689 : && LABEL_PRESERVE_P (block_label (bb)));
1920 : }
1921 :
1922 : /* E1 and E2 are edges with the same destination block. Search their
1923 : predecessors for common code. If found, redirect control flow from
1924 : (maybe the middle of) E1->SRC to (maybe the middle of) E2->SRC (dir_forward),
1925 : or the other way around (dir_backward). DIR specifies the allowed
1926 : replacement direction. */
1927 :
1928 : static bool
1929 51843155 : try_crossjump_to_edge (int mode, edge e1, edge e2,
1930 : enum replace_direction dir)
1931 : {
1932 51843155 : int nmatch;
1933 51843155 : basic_block src1 = e1->src, src2 = e2->src;
1934 51843155 : basic_block redirect_to, redirect_from, to_remove;
1935 51843155 : basic_block osrc1, osrc2, redirect_edges_to, tmp;
1936 51843155 : rtx_insn *newpos1, *newpos2;
1937 51843155 : edge s;
1938 51843155 : edge_iterator ei;
1939 :
1940 51843155 : newpos1 = newpos2 = NULL;
1941 :
1942 : /* Search backward through forwarder blocks. We don't need to worry
1943 : about multiple entry or chained forwarders, as they will be optimized
1944 : away. We do this to look past the unconditional jump following a
1945 : conditional jump that is required due to the current CFG shape. */
1946 51843155 : if (single_pred_p (src1)
1947 51843155 : && FORWARDER_BLOCK_P (src1))
1948 11990411 : e1 = single_pred_edge (src1), src1 = e1->src;
1949 :
1950 51843155 : if (single_pred_p (src2)
1951 51842948 : && FORWARDER_BLOCK_P (src2))
1952 5576951 : e2 = single_pred_edge (src2), src2 = e2->src;
1953 :
1954 : /* Nothing to do if we reach ENTRY, or a common source block. */
1955 51843155 : if (src1 == ENTRY_BLOCK_PTR_FOR_FN (cfun) || src2
1956 : == ENTRY_BLOCK_PTR_FOR_FN (cfun))
1957 : return false;
1958 51842723 : if (src1 == src2)
1959 : return false;
1960 :
1961 : /* Seeing more than 1 forwarder blocks would confuse us later... */
1962 51842600 : if (FORWARDER_BLOCK_P (e1->dest)
1963 51842600 : && FORWARDER_BLOCK_P (single_succ (e1->dest)))
1964 : return false;
1965 :
1966 51829622 : if (FORWARDER_BLOCK_P (e2->dest)
1967 51829622 : && FORWARDER_BLOCK_P (single_succ (e2->dest)))
1968 : return false;
1969 :
1970 : /* Likewise with dead code (possibly newly created by the other optimizations
1971 : of cfg_cleanup). */
1972 51828776 : if (EDGE_COUNT (src1->preds) == 0 || EDGE_COUNT (src2->preds) == 0)
1973 : return false;
1974 :
1975 : /* Do not turn corssing edge to non-crossing or vice versa after reload. */
1976 47354058 : if (BB_PARTITION (src1) != BB_PARTITION (src2)
1977 167682 : && reload_completed)
1978 : return false;
1979 :
1980 : /* Look for the common insn sequence, part the first ... */
1981 47186376 : if (!outgoing_edges_match (mode, src1, src2))
1982 : return false;
1983 :
1984 : /* ... and part the second. */
1985 16172620 : nmatch = flow_find_cross_jump (src1, src2, &newpos1, &newpos2, &dir);
1986 :
1987 16172620 : osrc1 = src1;
1988 16172620 : osrc2 = src2;
1989 16172620 : if (newpos1 != NULL_RTX)
1990 5385292 : src1 = BLOCK_FOR_INSN (newpos1);
1991 16172620 : if (newpos2 != NULL_RTX)
1992 5385292 : src2 = BLOCK_FOR_INSN (newpos2);
1993 :
1994 : /* Check that SRC1 and SRC2 have preds again. They may have changed
1995 : above due to the call to flow_find_cross_jump. */
1996 67679964 : if (EDGE_COUNT (src1->preds) == 0 || EDGE_COUNT (src2->preds) == 0)
1997 : return false;
1998 :
1999 16172620 : if (dir == dir_backward)
2000 : {
2001 900 : std::swap (osrc1, osrc2);
2002 900 : std::swap (src1, src2);
2003 900 : std::swap (e1, e2);
2004 900 : std::swap (newpos1, newpos2);
2005 : }
2006 :
2007 : /* Don't proceed with the crossjump unless we found a sufficient number
2008 : of matching instructions or the 'from' block was totally matched
2009 : (such that its predecessors will hopefully be redirected and the
2010 : block removed). */
2011 16172620 : if ((nmatch < param_min_crossjump_insns)
2012 16053801 : && (newpos1 != BB_HEAD (src1)))
2013 : return false;
2014 :
2015 : /* Avoid deleting preserve label when redirecting ABNORMAL edges. */
2016 365568 : if (block_has_preserve_label (e1->dest)
2017 365568 : && (e1->flags & EDGE_ABNORMAL))
2018 : return false;
2019 :
2020 : /* Here we know that the insns in the end of SRC1 which are common with SRC2
2021 : will be deleted.
2022 : If we have tablejumps in the end of SRC1 and SRC2
2023 : they have been already compared for equivalence in outgoing_edges_match ()
2024 : so replace the references to TABLE1 by references to TABLE2. */
2025 335811 : {
2026 335811 : rtx_insn *label1, *label2;
2027 335811 : rtx_jump_table_data *table1, *table2;
2028 :
2029 335811 : if (tablejump_p (BB_END (osrc1), &label1, &table1)
2030 4 : && tablejump_p (BB_END (osrc2), &label2, &table2)
2031 335815 : && label1 != label2)
2032 : {
2033 4 : rtx_insn *insn;
2034 :
2035 : /* Replace references to LABEL1 with LABEL2. */
2036 9246 : for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
2037 : {
2038 : /* Do not replace the label in SRC1->END because when deleting
2039 : a block whose end is a tablejump, the tablejump referenced
2040 : from the instruction is deleted too. */
2041 9242 : if (insn != BB_END (osrc1))
2042 9238 : replace_label_in_insn (insn, label1, label2, true);
2043 : }
2044 : }
2045 : }
2046 :
2047 : /* Avoid splitting if possible. We must always split when SRC2 has
2048 : EH predecessor edges, or we may end up with basic blocks with both
2049 : normal and EH predecessor edges. */
2050 335811 : if (newpos2 == BB_HEAD (src2)
2051 335811 : && !(EDGE_PRED (src2, 0)->flags & EDGE_EH))
2052 : redirect_to = src2;
2053 : else
2054 : {
2055 80637 : if (newpos2 == BB_HEAD (src2))
2056 : {
2057 : /* Skip possible basic block header. */
2058 5456 : if (LABEL_P (newpos2))
2059 5456 : newpos2 = NEXT_INSN (newpos2);
2060 5456 : while (DEBUG_INSN_P (newpos2))
2061 0 : newpos2 = NEXT_INSN (newpos2);
2062 5456 : if (NOTE_P (newpos2))
2063 5456 : newpos2 = NEXT_INSN (newpos2);
2064 5649 : while (DEBUG_INSN_P (newpos2))
2065 193 : newpos2 = NEXT_INSN (newpos2);
2066 : }
2067 :
2068 80637 : if (dump_file)
2069 0 : fprintf (dump_file, "Splitting bb %i before %i insns\n",
2070 : src2->index, nmatch);
2071 80637 : redirect_to = split_block (src2, PREV_INSN (newpos2))->dest;
2072 : }
2073 :
2074 335811 : if (dump_file)
2075 4 : fprintf (dump_file,
2076 : "Cross jumping from bb %i to bb %i; %i common insns\n",
2077 : src1->index, src2->index, nmatch);
2078 :
2079 : /* We may have some registers visible through the block. */
2080 335811 : df_set_bb_dirty (redirect_to);
2081 :
2082 335811 : if (osrc2 == src2)
2083 : redirect_edges_to = redirect_to;
2084 : else
2085 11104 : redirect_edges_to = osrc2;
2086 :
2087 : /* Recompute the counts of destinations of outgoing edges. */
2088 737463 : FOR_EACH_EDGE (s, ei, redirect_edges_to->succs)
2089 : {
2090 401652 : edge s2;
2091 401652 : edge_iterator ei;
2092 401652 : basic_block d = s->dest;
2093 :
2094 401652 : if (FORWARDER_BLOCK_P (d))
2095 28409 : d = single_succ (d);
2096 :
2097 467727 : FOR_EACH_EDGE (s2, ei, src1->succs)
2098 : {
2099 467727 : basic_block d2 = s2->dest;
2100 467727 : if (FORWARDER_BLOCK_P (d2))
2101 96437 : d2 = single_succ (d2);
2102 467727 : if (d == d2)
2103 : break;
2104 : }
2105 :
2106 : /* Take care to update possible forwarder blocks. We verified
2107 : that there is no more than one in the chain, so we can't run
2108 : into infinite loop. */
2109 401652 : if (FORWARDER_BLOCK_P (s->dest))
2110 28409 : s->dest->count += s->count ();
2111 :
2112 401652 : if (FORWARDER_BLOCK_P (s2->dest))
2113 74299 : s2->dest->count -= s->count ();
2114 :
2115 401652 : s->probability = s->probability.combine_with_count
2116 401652 : (redirect_edges_to->count,
2117 : s2->probability, src1->count);
2118 : }
2119 :
2120 : /* Adjust count for the block. An earlier jump
2121 : threading pass may have left the profile in an inconsistent
2122 : state (see update_bb_profile_for_threading) so we must be
2123 : prepared for overflows. */
2124 : tmp = redirect_to;
2125 359259 : do
2126 : {
2127 347535 : tmp->count += src1->count;
2128 347535 : if (tmp == redirect_edges_to)
2129 : break;
2130 11724 : tmp = find_fallthru_edge (tmp->succs)->dest;
2131 : }
2132 : while (true);
2133 335811 : update_br_prob_note (redirect_edges_to);
2134 :
2135 : /* Edit SRC1 to go to REDIRECT_TO at NEWPOS1. */
2136 :
2137 : /* Skip possible basic block header. */
2138 335811 : if (LABEL_P (newpos1))
2139 135388 : newpos1 = NEXT_INSN (newpos1);
2140 :
2141 355177 : while (DEBUG_INSN_P (newpos1))
2142 19366 : newpos1 = NEXT_INSN (newpos1);
2143 :
2144 335811 : if (NOTE_INSN_BASIC_BLOCK_P (newpos1))
2145 254268 : newpos1 = NEXT_INSN (newpos1);
2146 :
2147 : /* Skip also prologue and function markers. */
2148 806672 : while (DEBUG_INSN_P (newpos1)
2149 806672 : || (NOTE_P (newpos1)
2150 13063 : && (NOTE_KIND (newpos1) == NOTE_INSN_PROLOGUE_END
2151 13063 : || NOTE_KIND (newpos1) == NOTE_INSN_FUNCTION_BEG)))
2152 470861 : newpos1 = NEXT_INSN (newpos1);
2153 :
2154 335811 : redirect_from = split_block (src1, PREV_INSN (newpos1))->src;
2155 335811 : to_remove = single_succ (redirect_from);
2156 :
2157 335811 : redirect_edge_and_branch_force (single_succ_edge (redirect_from), redirect_to);
2158 335811 : delete_basic_block (to_remove);
2159 :
2160 335811 : update_forwarder_flag (redirect_from);
2161 335811 : if (redirect_to != src2)
2162 80637 : update_forwarder_flag (src2);
2163 :
2164 : return true;
2165 : }
2166 :
2167 : /* Search the predecessors of BB for common insn sequences. When found,
2168 : share code between them by redirecting control flow. Return true if
2169 : any changes made. */
2170 :
2171 : static bool
2172 30231395 : try_crossjump_bb (int mode, basic_block bb)
2173 : {
2174 30231395 : edge e, e2, fallthru;
2175 30231395 : bool changed;
2176 30231395 : unsigned max, ix, ix2;
2177 :
2178 : /* Nothing to do if there is not at least two incoming edges. */
2179 30434748 : if (EDGE_COUNT (bb->preds) < 2)
2180 : return false;
2181 :
2182 : /* Don't crossjump if this block ends in a computed jump,
2183 : unless we are optimizing for size. */
2184 8325123 : if (optimize_bb_for_size_p (bb)
2185 1294822 : && bb != EXIT_BLOCK_PTR_FOR_FN (cfun)
2186 9581205 : && computed_jump_p (BB_END (bb)))
2187 : return false;
2188 :
2189 : /* If we are partitioning hot/cold basic blocks, we don't want to
2190 : mess up unconditional or indirect jumps that cross between hot
2191 : and cold sections.
2192 :
2193 : Basic block partitioning may result in some jumps that appear to
2194 : be optimizable (or blocks that appear to be mergeable), but which really
2195 : must be left untouched (they are required to make it safely across
2196 : partition boundaries). See the comments at the top of
2197 : bb-reorder.cc:partition_hot_cold_basic_blocks for complete details. */
2198 :
2199 8325094 : if (BB_PARTITION (EDGE_PRED (bb, 0)->src) !=
2200 8325094 : BB_PARTITION (EDGE_PRED (bb, 1)->src)
2201 8325094 : || (EDGE_PRED (bb, 0)->flags & EDGE_CROSSING))
2202 : return false;
2203 :
2204 : /* It is always cheapest to redirect a block that ends in a branch to
2205 : a block that falls through into BB, as that adds no branches to the
2206 : program. We'll try that combination first. */
2207 8124549 : fallthru = NULL;
2208 8124549 : max = param_max_crossjump_edges;
2209 :
2210 8124549 : if (EDGE_COUNT (bb->preds) > max)
2211 : return false;
2212 :
2213 8121770 : fallthru = find_fallthru_edge (bb->preds);
2214 :
2215 8121770 : changed = false;
2216 39899683 : for (ix = 0; ix < EDGE_COUNT (bb->preds);)
2217 : {
2218 23656143 : e = EDGE_PRED (bb, ix);
2219 23656143 : ix++;
2220 :
2221 : /* As noted above, first try with the fallthru predecessor (or, a
2222 : fallthru predecessor if we are in cfglayout mode). */
2223 23656143 : if (fallthru)
2224 : {
2225 : /* Don't combine the fallthru edge into anything else.
2226 : If there is a match, we'll do it the other way around. */
2227 17559357 : if (e == fallthru)
2228 6576536 : continue;
2229 : /* If nothing changed since the last attempt, there is nothing
2230 : we can do. */
2231 10982821 : if (!first_pass
2232 4281301 : && !((e->src->flags & BB_MODIFIED)
2233 3418011 : || (fallthru->src->flags & BB_MODIFIED)))
2234 3022660 : continue;
2235 :
2236 7960161 : if (try_crossjump_to_edge (mode, e, fallthru, dir_forward))
2237 : {
2238 148226 : changed = true;
2239 148226 : ix = 0;
2240 148226 : continue;
2241 : }
2242 : }
2243 :
2244 : /* Non-obvious work limiting check: Recognize that we're going
2245 : to call try_crossjump_bb on every basic block. So if we have
2246 : two blocks with lots of outgoing edges (a switch) and they
2247 : share lots of common destinations, then we would do the
2248 : cross-jump check once for each common destination.
2249 :
2250 : Now, if the blocks actually are cross-jump candidates, then
2251 : all of their destinations will be shared. Which means that
2252 : we only need check them for cross-jump candidacy once. We
2253 : can eliminate redundant checks of crossjump(A,B) by arbitrarily
2254 : choosing to do the check from the block for which the edge
2255 : in question is the first successor of A. */
2256 13908721 : if (EDGE_SUCC (e->src, 0) != e)
2257 2802602 : continue;
2258 :
2259 167654619 : for (ix2 = 0; ix2 < EDGE_COUNT (bb->preds); ix2++)
2260 : {
2261 124958172 : e2 = EDGE_PRED (bb, ix2);
2262 :
2263 124958172 : if (e2 == e)
2264 11017032 : continue;
2265 :
2266 : /* We've already checked the fallthru edge above. */
2267 113941140 : if (e2 == fallthru)
2268 6269898 : continue;
2269 :
2270 : /* The "first successor" check above only prevents multiple
2271 : checks of crossjump(A,B). In order to prevent redundant
2272 : checks of crossjump(B,A), require that A be the block
2273 : with the lowest index. */
2274 107671242 : if (e->src->index > e2->src->index)
2275 53892153 : continue;
2276 :
2277 : /* If nothing changed since the last attempt, there is nothing
2278 : we can do. */
2279 53779089 : if (!first_pass
2280 13152214 : && !((e->src->flags & BB_MODIFIED)
2281 10770190 : || (e2->src->flags & BB_MODIFIED)))
2282 9896095 : continue;
2283 :
2284 : /* Both e and e2 are not fallthru edges, so we can crossjump in either
2285 : direction. */
2286 43882994 : if (try_crossjump_to_edge (mode, e, e2, dir_both))
2287 : {
2288 : changed = true;
2289 : ix = 0;
2290 : break;
2291 : }
2292 : }
2293 : }
2294 :
2295 8121770 : if (changed)
2296 159527 : crossjumps_occurred = true;
2297 :
2298 : return changed;
2299 : }
2300 :
2301 : /* Search the successors of BB for common insn sequences. When found,
2302 : share code between them by moving it across the basic block
2303 : boundary. Return true if any changes made. */
2304 :
2305 : static bool
2306 29035441 : try_head_merge_bb (basic_block bb)
2307 : {
2308 29035441 : basic_block final_dest_bb = NULL;
2309 29035441 : int max_match = INT_MAX;
2310 29035441 : edge e0;
2311 29035441 : rtx_insn **headptr, **currptr, **nextptr;
2312 29035441 : bool changed, moveall;
2313 29035441 : unsigned ix;
2314 29035441 : rtx_insn *e0_last_head;
2315 29035441 : rtx cond;
2316 29035441 : rtx_insn *move_before;
2317 29035441 : unsigned nedges = EDGE_COUNT (bb->succs);
2318 29035441 : rtx_insn *jump = BB_END (bb);
2319 29035441 : regset live, live_union;
2320 :
2321 : /* Nothing to do if there is not at least two outgoing edges. */
2322 29035441 : if (nedges < 2)
2323 : return false;
2324 :
2325 : /* Don't crossjump if this block ends in a computed jump,
2326 : unless we are optimizing for size. */
2327 14877814 : if (optimize_bb_for_size_p (bb)
2328 1740535 : && bb != EXIT_BLOCK_PTR_FOR_FN (cfun)
2329 16618349 : && computed_jump_p (BB_END (bb)))
2330 : return false;
2331 :
2332 14877787 : cond = get_condition (jump, &move_before, true, false);
2333 14877787 : if (cond == NULL_RTX)
2334 1881987 : move_before = jump;
2335 :
2336 44915926 : for (ix = 0; ix < nedges; ix++)
2337 30038139 : if (EDGE_SUCC (bb, ix)->dest == EXIT_BLOCK_PTR_FOR_FN (cfun))
2338 : return false;
2339 :
2340 27892489 : for (ix = 0; ix < nedges; ix++)
2341 : {
2342 23234472 : edge e = EDGE_SUCC (bb, ix);
2343 23234472 : basic_block other_bb = e->dest;
2344 :
2345 23234472 : if (df_get_bb_dirty (other_bb))
2346 : {
2347 550613 : block_was_dirty = true;
2348 550613 : return false;
2349 : }
2350 :
2351 22683859 : if (e->flags & EDGE_ABNORMAL)
2352 : return false;
2353 :
2354 : /* Normally, all destination blocks must only be reachable from this
2355 : block, i.e. they must have one incoming edge.
2356 :
2357 : There is one special case we can handle, that of multiple consecutive
2358 : jumps where the first jumps to one of the targets of the second jump.
2359 : This happens frequently in switch statements for default labels.
2360 : The structure is as follows:
2361 : FINAL_DEST_BB
2362 : ....
2363 : if (cond) jump A;
2364 : fall through
2365 : BB
2366 : jump with targets A, B, C, D...
2367 : A
2368 : has two incoming edges, from FINAL_DEST_BB and BB
2369 :
2370 : In this case, we can try to move the insns through BB and into
2371 : FINAL_DEST_BB. */
2372 20882404 : if (EDGE_COUNT (other_bb->preds) != 1)
2373 : {
2374 8218094 : edge incoming_edge, incoming_bb_other_edge;
2375 8218094 : edge_iterator ei;
2376 :
2377 8218094 : if (final_dest_bb != NULL
2378 8218094 : || EDGE_COUNT (other_bb->preds) != 2)
2379 7867702 : return false;
2380 :
2381 : /* We must be able to move the insns across the whole block. */
2382 4505145 : move_before = BB_HEAD (bb);
2383 28909001 : while (!NONDEBUG_INSN_P (move_before))
2384 24403856 : move_before = NEXT_INSN (move_before);
2385 :
2386 4505145 : if (EDGE_COUNT (bb->preds) != 1)
2387 : return false;
2388 2691569 : incoming_edge = EDGE_PRED (bb, 0);
2389 2691569 : final_dest_bb = incoming_edge->src;
2390 10068831 : if (EDGE_COUNT (final_dest_bb->succs) != 2)
2391 : return false;
2392 3173860 : FOR_EACH_EDGE (incoming_bb_other_edge, ei, final_dest_bb->succs)
2393 3173860 : if (incoming_bb_other_edge != incoming_edge)
2394 : break;
2395 2201129 : if (incoming_bb_other_edge->dest != other_bb)
2396 : return false;
2397 : }
2398 : }
2399 :
2400 4658017 : e0 = EDGE_SUCC (bb, 0);
2401 4658017 : e0_last_head = NULL;
2402 4658017 : changed = false;
2403 :
2404 4775200 : for (ix = 1; ix < nedges; ix++)
2405 : {
2406 4662594 : edge e = EDGE_SUCC (bb, ix);
2407 4662594 : rtx_insn *e0_last, *e_last;
2408 4662594 : int nmatch;
2409 :
2410 4662594 : nmatch = flow_find_head_matching_sequence (e0->dest, e->dest,
2411 : &e0_last, &e_last, 0);
2412 4662594 : if (nmatch == 0)
2413 4545411 : return false;
2414 :
2415 117183 : if (nmatch < max_match)
2416 : {
2417 112804 : max_match = nmatch;
2418 112804 : e0_last_head = e0_last;
2419 : }
2420 : }
2421 :
2422 : /* If we matched an entire block, we probably have to avoid moving the
2423 : last insn. */
2424 112606 : if (max_match > 0
2425 112606 : && e0_last_head == BB_END (e0->dest)
2426 121880 : && (find_reg_note (e0_last_head, REG_EH_REGION, 0)
2427 7729 : || control_flow_insn_p (e0_last_head)))
2428 : {
2429 1557 : max_match--;
2430 1557 : if (max_match == 0)
2431 : return false;
2432 252 : e0_last_head = prev_real_nondebug_insn (e0_last_head);
2433 : }
2434 :
2435 111301 : if (max_match == 0)
2436 : return false;
2437 :
2438 : /* We must find a union of the live registers at each of the end points. */
2439 111301 : live = BITMAP_ALLOC (NULL);
2440 111301 : live_union = BITMAP_ALLOC (NULL);
2441 :
2442 111301 : currptr = XNEWVEC (rtx_insn *, nedges);
2443 111301 : headptr = XNEWVEC (rtx_insn *, nedges);
2444 111301 : nextptr = XNEWVEC (rtx_insn *, nedges);
2445 :
2446 338157 : for (ix = 0; ix < nedges; ix++)
2447 : {
2448 226856 : int j;
2449 226856 : basic_block merge_bb = EDGE_SUCC (bb, ix)->dest;
2450 226856 : rtx_insn *head = BB_HEAD (merge_bb);
2451 :
2452 1496297 : while (!NONDEBUG_INSN_P (head))
2453 1269441 : head = NEXT_INSN (head);
2454 226856 : headptr[ix] = head;
2455 226856 : currptr[ix] = head;
2456 :
2457 : /* Compute the end point and live information */
2458 369038 : for (j = 1; j < max_match; j++)
2459 202652 : do
2460 202652 : head = NEXT_INSN (head);
2461 202652 : while (!NONDEBUG_INSN_P (head));
2462 226856 : simulate_backwards_to_point (merge_bb, live, head);
2463 226856 : IOR_REG_SET (live_union, live);
2464 : }
2465 :
2466 : /* If we're moving across two blocks, verify the validity of the
2467 : first move, then adjust the target and let the loop below deal
2468 : with the final move. */
2469 111301 : if (final_dest_bb != NULL)
2470 : {
2471 7080 : rtx_insn *move_upto;
2472 :
2473 7080 : moveall = can_move_insns_across (currptr[0], e0_last_head, move_before,
2474 : jump, e0->dest, live_union,
2475 : NULL, &move_upto);
2476 7080 : if (!moveall)
2477 : {
2478 5900 : if (move_upto == NULL_RTX)
2479 5529 : goto out;
2480 :
2481 1132 : while (e0_last_head != move_upto)
2482 : {
2483 761 : df_simulate_one_insn_backwards (e0->dest, e0_last_head,
2484 : live_union);
2485 761 : e0_last_head = PREV_INSN (e0_last_head);
2486 : }
2487 : }
2488 1551 : if (e0_last_head == NULL_RTX)
2489 0 : goto out;
2490 :
2491 1551 : jump = BB_END (final_dest_bb);
2492 1551 : cond = get_condition (jump, &move_before, true, false);
2493 1551 : if (cond == NULL_RTX)
2494 0 : move_before = jump;
2495 : }
2496 :
2497 179458 : do
2498 : {
2499 179458 : rtx_insn *move_upto;
2500 179458 : moveall = can_move_insns_across (currptr[0], e0_last_head,
2501 : move_before, jump, e0->dest, live_union,
2502 : NULL, &move_upto);
2503 179458 : if (!moveall && move_upto == NULL_RTX)
2504 : {
2505 138401 : if (jump == move_before)
2506 : break;
2507 :
2508 : /* Try again, using a different insertion point. */
2509 70025 : move_before = jump;
2510 :
2511 70025 : continue;
2512 : }
2513 :
2514 41057 : if (final_dest_bb && !moveall)
2515 : /* We haven't checked whether a partial move would be OK for the first
2516 : move, so we have to fail this case. */
2517 : break;
2518 :
2519 59854 : changed = true;
2520 59854 : for (;;)
2521 : {
2522 59854 : if (currptr[0] == move_upto)
2523 : break;
2524 56779 : for (ix = 0; ix < nedges; ix++)
2525 : {
2526 37877 : rtx_insn *curr = currptr[ix];
2527 58290 : do
2528 58290 : curr = NEXT_INSN (curr);
2529 58290 : while (!NONDEBUG_INSN_P (curr));
2530 37877 : currptr[ix] = curr;
2531 : }
2532 : }
2533 :
2534 : /* If we can't currently move all of the identical insns, remember
2535 : each insn after the range that we'll merge. */
2536 40952 : if (!moveall)
2537 14430 : for (ix = 0; ix < nedges; ix++)
2538 : {
2539 9634 : rtx_insn *curr = currptr[ix];
2540 15331 : do
2541 15331 : curr = NEXT_INSN (curr);
2542 15331 : while (!NONDEBUG_INSN_P (curr));
2543 9634 : nextptr[ix] = curr;
2544 : }
2545 :
2546 40952 : reorder_insns (headptr[0], currptr[0], PREV_INSN (move_before));
2547 40952 : df_set_bb_dirty (EDGE_SUCC (bb, 0)->dest);
2548 40952 : if (final_dest_bb != NULL)
2549 1441 : df_set_bb_dirty (final_dest_bb);
2550 40952 : df_set_bb_dirty (bb);
2551 124257 : for (ix = 1; ix < nedges; ix++)
2552 : {
2553 42353 : df_set_bb_dirty (EDGE_SUCC (bb, ix)->dest);
2554 42353 : delete_insn_chain (headptr[ix], currptr[ix], false);
2555 : }
2556 40952 : if (!moveall)
2557 : {
2558 4796 : if (jump == move_before)
2559 : break;
2560 :
2561 : /* For the unmerged insns, try a different insertion point. */
2562 3661 : move_before = jump;
2563 :
2564 10983 : for (ix = 0; ix < nedges; ix++)
2565 7322 : currptr[ix] = headptr[ix] = nextptr[ix];
2566 : }
2567 : }
2568 109842 : while (!moveall);
2569 :
2570 36156 : out:
2571 111301 : free (currptr);
2572 111301 : free (headptr);
2573 111301 : free (nextptr);
2574 :
2575 111301 : crossjumps_occurred |= changed;
2576 :
2577 111301 : return changed;
2578 : }
2579 :
2580 : /* Return true if BB contains just bb note, or bb note followed
2581 : by only DEBUG_INSNs. */
2582 :
2583 : static bool
2584 15991420 : trivially_empty_bb_p (basic_block bb)
2585 : {
2586 15991420 : rtx_insn *insn = BB_END (bb);
2587 :
2588 6886 : while (1)
2589 : {
2590 15998306 : if (insn == BB_HEAD (bb))
2591 : return true;
2592 15997445 : if (!DEBUG_INSN_P (insn))
2593 : return false;
2594 6886 : insn = PREV_INSN (insn);
2595 : }
2596 : }
2597 :
2598 : /* Return true if BB contains just a return and possibly a USE of the
2599 : return value. Fill in *RET and *USE with the return and use insns
2600 : if any found, otherwise NULL. All CLOBBERs are ignored. */
2601 :
2602 : bool
2603 404437220 : bb_is_just_return (basic_block bb, rtx_insn **ret, rtx_insn **use)
2604 : {
2605 404437220 : *ret = *use = NULL;
2606 404437220 : rtx_insn *insn;
2607 :
2608 404437220 : if (bb == EXIT_BLOCK_PTR_FOR_FN (cfun))
2609 : return false;
2610 :
2611 533877208 : FOR_BB_INSNS_REVERSE (bb, insn)
2612 520526826 : if (NONDEBUG_INSN_P (insn))
2613 : {
2614 400099414 : rtx pat = PATTERN (insn);
2615 :
2616 400099414 : if (!*ret && ANY_RETURN_P (pat))
2617 7522047 : *ret = insn;
2618 7871932 : else if (*ret && !*use && GET_CODE (pat) == USE
2619 1128841 : && REG_P (XEXP (pat, 0))
2620 393706208 : && REG_FUNCTION_VALUE_P (XEXP (pat, 0)))
2621 1125920 : *use = insn;
2622 391451447 : else if (GET_CODE (pat) != CLOBBER)
2623 : return false;
2624 : }
2625 :
2626 13350382 : return !!*ret;
2627 : }
2628 :
2629 : /* Do simple CFG optimizations - basic block merging, simplifying of jump
2630 : instructions etc. Return nonzero if changes were made. */
2631 :
2632 : static bool
2633 21777400 : try_optimize_cfg (int mode)
2634 : {
2635 21777400 : bool changed_overall = false;
2636 21777400 : bool changed;
2637 21777400 : int iterations = 0;
2638 21777400 : basic_block bb, b, next;
2639 :
2640 21777400 : if (mode & (CLEANUP_CROSSJUMP | CLEANUP_THREADING))
2641 2971848 : clear_bb_flags ();
2642 :
2643 21777400 : crossjumps_occurred = false;
2644 :
2645 318244177 : FOR_EACH_BB_FN (bb, cfun)
2646 296466777 : update_forwarder_flag (bb);
2647 :
2648 21777400 : if (! targetm.cannot_modify_jumps_p ())
2649 : {
2650 21777400 : first_pass = true;
2651 : /* Attempt to merge blocks as made possible by edge removal. If
2652 : a block has only one successor, and the successor has only
2653 : one predecessor, they may be combined. */
2654 51244944 : do
2655 : {
2656 25622472 : block_was_dirty = false;
2657 25622472 : changed = false;
2658 25622472 : iterations++;
2659 :
2660 25622472 : if (dump_file)
2661 1759 : fprintf (dump_file,
2662 : "\n\ntry_optimize_cfg iteration %i\n\n",
2663 : iterations);
2664 :
2665 25622472 : for (b = ENTRY_BLOCK_PTR_FOR_FN (cfun)->next_bb; b
2666 430578545 : != EXIT_BLOCK_PTR_FOR_FN (cfun);)
2667 : {
2668 404956073 : basic_block c;
2669 404956073 : edge s;
2670 404956073 : bool changed_here = false;
2671 :
2672 : /* Delete trivially dead basic blocks. This is either
2673 : blocks with no predecessors, or empty blocks with no
2674 : successors. However if the empty block with no
2675 : successors is the successor of the ENTRY_BLOCK, it is
2676 : kept. This ensures that the ENTRY_BLOCK will have a
2677 : successor which is a precondition for many RTL
2678 : passes. Empty blocks may result from expanding
2679 : __builtin_unreachable (). */
2680 404956073 : if (EDGE_COUNT (b->preds) == 0
2681 404956073 : || (EDGE_COUNT (b->succs) == 0
2682 15991420 : && trivially_empty_bb_p (b)
2683 861 : && single_succ_edge (ENTRY_BLOCK_PTR_FOR_FN (cfun))->dest
2684 : != b))
2685 : {
2686 5457935 : c = b->prev_bb;
2687 5457935 : if (EDGE_COUNT (b->preds) > 0)
2688 : {
2689 861 : edge e;
2690 861 : edge_iterator ei;
2691 :
2692 861 : if (current_ir_type () == IR_RTL_CFGLAYOUT)
2693 : {
2694 52 : rtx_insn *insn;
2695 52 : for (insn = BB_FOOTER (b);
2696 52 : insn; insn = NEXT_INSN (insn))
2697 52 : if (BARRIER_P (insn))
2698 : break;
2699 52 : if (insn)
2700 104 : FOR_EACH_EDGE (e, ei, b->preds)
2701 52 : if ((e->flags & EDGE_FALLTHRU))
2702 : {
2703 52 : if (BB_FOOTER (b)
2704 52 : && BB_FOOTER (e->src) == NULL)
2705 : {
2706 52 : BB_FOOTER (e->src) = BB_FOOTER (b);
2707 52 : BB_FOOTER (b) = NULL;
2708 : }
2709 : else
2710 0 : emit_barrier_after_bb (e->src);
2711 : }
2712 : }
2713 : else
2714 : {
2715 809 : rtx_insn *last = get_last_bb_insn (b);
2716 809 : if (last && BARRIER_P (last))
2717 1618 : FOR_EACH_EDGE (e, ei, b->preds)
2718 809 : if ((e->flags & EDGE_FALLTHRU))
2719 809 : emit_barrier_after (BB_END (e->src));
2720 : }
2721 : }
2722 5457935 : delete_basic_block (b);
2723 5457935 : changed = true;
2724 : /* Avoid trying to remove the exit block. */
2725 5457935 : b = (c == ENTRY_BLOCK_PTR_FOR_FN (cfun) ? c->next_bb : c);
2726 5593763 : continue;
2727 5457935 : }
2728 :
2729 : /* Remove code labels no longer used. */
2730 399498138 : if (single_pred_p (b)
2731 290180181 : && (single_pred_edge (b)->flags & EDGE_FALLTHRU)
2732 204248215 : && !(single_pred_edge (b)->flags & EDGE_COMPLEX)
2733 201381195 : && LABEL_P (BB_HEAD (b))
2734 831359 : && !LABEL_PRESERVE_P (BB_HEAD (b))
2735 : /* If the previous block ends with a branch to this
2736 : block, we can't delete the label. Normally this
2737 : is a condjump that is yet to be simplified, but
2738 : if CASE_DROPS_THRU, this can be a tablejump with
2739 : some element going to the same place as the
2740 : default (fallthru). */
2741 400309827 : && (single_pred (b) == ENTRY_BLOCK_PTR_FOR_FN (cfun)
2742 811635 : || !JUMP_P (BB_END (single_pred (b)))
2743 617548 : || ! label_is_jump_target_p (BB_HEAD (b),
2744 617548 : BB_END (single_pred (b)))))
2745 : {
2746 805548 : delete_insn (BB_HEAD (b));
2747 805548 : if (dump_file)
2748 37 : fprintf (dump_file, "Deleted label in block %i.\n",
2749 : b->index);
2750 : }
2751 :
2752 : /* If we fall through an empty block, we can remove it. */
2753 399633966 : if (!(mode & (CLEANUP_CFGLAYOUT | CLEANUP_NO_INSN_DEL))
2754 84809258 : && single_pred_p (b)
2755 62714336 : && (single_pred_edge (b)->flags & EDGE_FALLTHRU)
2756 44298371 : && !LABEL_P (BB_HEAD (b))
2757 43946656 : && FORWARDER_BLOCK_P (b)
2758 : /* Note that forwarder_block_p true ensures that
2759 : there is a successor for this block. */
2760 5261762 : && (single_succ_edge (b)->flags & EDGE_FALLTHRU)
2761 399719540 : && n_basic_blocks_for_fn (cfun) > NUM_FIXED_BLOCKS + 1)
2762 : {
2763 135828 : if (dump_file)
2764 11 : fprintf (dump_file,
2765 : "Deleting fallthru block %i.\n",
2766 : b->index);
2767 :
2768 2620 : c = ((b->prev_bb == ENTRY_BLOCK_PTR_FOR_FN (cfun))
2769 135828 : ? b->next_bb : b->prev_bb);
2770 135828 : redirect_edge_succ_nodup (single_pred_edge (b),
2771 : single_succ (b));
2772 135828 : delete_basic_block (b);
2773 135828 : changed = true;
2774 135828 : b = c;
2775 135828 : continue;
2776 : }
2777 :
2778 : /* Merge B with its single successor, if any. */
2779 399362310 : if (single_succ_p (b)
2780 175181740 : && (s = single_succ_edge (b))
2781 175181740 : && !(s->flags & EDGE_COMPLEX)
2782 166668544 : && (c = s->dest) != EXIT_BLOCK_PTR_FOR_FN (cfun)
2783 408151747 : && single_pred_p (c)
2784 406552744 : && b != c)
2785 : {
2786 : /* When not in cfg_layout mode use code aware of reordering
2787 : INSN. This code possibly creates new basic blocks so it
2788 : does not fit merge_blocks interface and is kept here in
2789 : hope that it will become useless once more of compiler
2790 : is transformed to use cfg_layout mode. */
2791 :
2792 8789437 : if ((mode & CLEANUP_CFGLAYOUT)
2793 8789437 : && can_merge_blocks_p (b, c))
2794 : {
2795 790327 : merge_blocks (b, c);
2796 790327 : update_forwarder_flag (b);
2797 790327 : changed_here = true;
2798 : }
2799 7999110 : else if (!(mode & CLEANUP_CFGLAYOUT)
2800 : /* If the jump insn has side effects,
2801 : we can't kill the edge. */
2802 6771978 : && (!JUMP_P (BB_END (b))
2803 2181431 : || (reload_completed
2804 3017760 : ? simplejump_p (BB_END (b))
2805 836329 : : (onlyjump_p (BB_END (b))
2806 835538 : && !tablejump_p (BB_END (b),
2807 : NULL, NULL))))
2808 17786902 : && (next = merge_blocks_move (s, b, c, mode)))
2809 : {
2810 : b = next;
2811 : changed_here = true;
2812 : }
2813 : }
2814 :
2815 : /* Try to change a branch to a return to just that return. */
2816 399362310 : rtx_insn *ret, *use;
2817 399362310 : if (single_succ_p (b)
2818 173530916 : && onlyjump_p (BB_END (b))
2819 426704763 : && bb_is_just_return (single_succ (b), &ret, &use))
2820 : {
2821 37517 : if (redirect_jump (as_a <rtx_jump_insn *> (BB_END (b)),
2822 37517 : PATTERN (ret), 0))
2823 : {
2824 37517 : if (use)
2825 21609 : emit_insn_before (copy_insn (PATTERN (use)),
2826 21609 : BB_END (b));
2827 37517 : if (dump_file)
2828 23 : fprintf (dump_file, "Changed jump %d->%d to return.\n",
2829 23 : b->index, single_succ (b)->index);
2830 37517 : redirect_edge_succ (single_succ_edge (b),
2831 37517 : EXIT_BLOCK_PTR_FOR_FN (cfun));
2832 37517 : single_succ_edge (b)->flags &= ~EDGE_CROSSING;
2833 37517 : changed_here = true;
2834 : }
2835 : }
2836 :
2837 : /* Try to change a conditional branch to a return to the
2838 : respective conditional return. */
2839 399362310 : if (EDGE_COUNT (b->succs) == 2
2840 209342001 : && any_condjump_p (BB_END (b))
2841 583352779 : && bb_is_just_return (BRANCH_EDGE (b)->dest, &ret, &use))
2842 : {
2843 587480 : if (redirect_jump (as_a <rtx_jump_insn *> (BB_END (b)),
2844 587480 : PATTERN (ret), 0))
2845 : {
2846 0 : if (use)
2847 0 : emit_insn_before (copy_insn (PATTERN (use)),
2848 0 : BB_END (b));
2849 0 : if (dump_file)
2850 0 : fprintf (dump_file, "Changed conditional jump %d->%d "
2851 : "to conditional return.\n",
2852 0 : b->index, BRANCH_EDGE (b)->dest->index);
2853 0 : redirect_edge_succ (BRANCH_EDGE (b),
2854 0 : EXIT_BLOCK_PTR_FOR_FN (cfun));
2855 0 : BRANCH_EDGE (b)->flags &= ~EDGE_CROSSING;
2856 0 : changed_here = true;
2857 : }
2858 : }
2859 :
2860 : /* Try to flip a conditional branch that falls through to
2861 : a return so that it becomes a conditional return and a
2862 : new jump to the original branch target. */
2863 399362310 : if (EDGE_COUNT (b->succs) == 2
2864 209342001 : && BRANCH_EDGE (b)->dest != EXIT_BLOCK_PTR_FOR_FN (cfun)
2865 209342001 : && any_condjump_p (BB_END (b))
2866 583352779 : && bb_is_just_return (FALLTHRU_EDGE (b)->dest, &ret, &use))
2867 : {
2868 157914 : if (invert_jump (as_a <rtx_jump_insn *> (BB_END (b)),
2869 157914 : JUMP_LABEL (BB_END (b)), 0))
2870 : {
2871 157914 : basic_block new_ft = BRANCH_EDGE (b)->dest;
2872 157914 : if (redirect_jump (as_a <rtx_jump_insn *> (BB_END (b)),
2873 157914 : PATTERN (ret), 0))
2874 : {
2875 0 : if (use)
2876 0 : emit_insn_before (copy_insn (PATTERN (use)),
2877 0 : BB_END (b));
2878 0 : if (dump_file)
2879 0 : fprintf (dump_file, "Changed conditional jump "
2880 : "%d->%d to conditional return, adding "
2881 : "fall-through jump.\n",
2882 0 : b->index, BRANCH_EDGE (b)->dest->index);
2883 0 : redirect_edge_succ (BRANCH_EDGE (b),
2884 0 : EXIT_BLOCK_PTR_FOR_FN (cfun));
2885 0 : BRANCH_EDGE (b)->flags &= ~EDGE_CROSSING;
2886 0 : std::swap (BRANCH_EDGE (b)->probability,
2887 0 : FALLTHRU_EDGE (b)->probability);
2888 0 : update_br_prob_note (b);
2889 0 : basic_block jb = force_nonfallthru (FALLTHRU_EDGE (b));
2890 0 : notice_new_block (jb);
2891 0 : if (!redirect_jump (as_a <rtx_jump_insn *> (BB_END (jb)),
2892 0 : block_label (new_ft), 0))
2893 0 : gcc_unreachable ();
2894 0 : redirect_edge_succ (single_succ_edge (jb), new_ft);
2895 0 : changed_here = true;
2896 : }
2897 : else
2898 : {
2899 : /* Invert the jump back to what it was. This should
2900 : never fail. */
2901 157914 : if (!invert_jump (as_a <rtx_jump_insn *> (BB_END (b)),
2902 157914 : JUMP_LABEL (BB_END (b)), 0))
2903 0 : gcc_unreachable ();
2904 : }
2905 : }
2906 : }
2907 :
2908 : /* Simplify branch over branch. */
2909 399362310 : if ((mode & CLEANUP_EXPENSIVE)
2910 105568450 : && !(mode & CLEANUP_CFGLAYOUT)
2911 433369991 : && try_simplify_condjump (b))
2912 : changed_here = true;
2913 :
2914 : /* If B has a single outgoing edge, but uses a
2915 : non-trivial jump instruction without side-effects, we
2916 : can either delete the jump entirely, or replace it
2917 : with a simple unconditional jump. */
2918 399362310 : if (single_succ_p (b)
2919 173530949 : && single_succ (b) != EXIT_BLOCK_PTR_FOR_FN (cfun)
2920 143827335 : && onlyjump_p (BB_END (b))
2921 28971617 : && !CROSSING_JUMP_P (BB_END (b))
2922 425637677 : && try_redirect_by_replacing_jump (single_succ_edge (b),
2923 : single_succ (b),
2924 27942654 : (mode & CLEANUP_CFGLAYOUT) != 0))
2925 : {
2926 4241152 : update_forwarder_flag (b);
2927 4241152 : changed_here = true;
2928 : }
2929 :
2930 : /* Simplify branch to branch. */
2931 399362310 : if (try_forward_edges (mode, b))
2932 : {
2933 6399799 : update_forwarder_flag (b);
2934 6399799 : changed_here = true;
2935 : }
2936 :
2937 : /* Look for shared code between blocks. */
2938 399362310 : if ((mode & CLEANUP_CROSSJUMP)
2939 399362310 : && try_crossjump_bb (mode, b))
2940 : changed_here = true;
2941 :
2942 399362310 : if ((mode & CLEANUP_CROSSJUMP)
2943 : /* This can lengthen register lifetimes. Do it only after
2944 : reload. */
2945 29035441 : && reload_completed
2946 428397751 : && try_head_merge_bb (b))
2947 : changed_here = true;
2948 :
2949 : /* Don't get confused by the index shift caused by
2950 : deleting blocks. */
2951 399322276 : if (!changed_here)
2952 384608617 : b = b->next_bb;
2953 : else
2954 : changed = true;
2955 : }
2956 :
2957 25622472 : if ((mode & CLEANUP_CROSSJUMP)
2958 25622472 : && try_crossjump_bb (mode, EXIT_BLOCK_PTR_FOR_FN (cfun)))
2959 : changed = true;
2960 :
2961 25622472 : if (block_was_dirty)
2962 : {
2963 : /* This should only be set by head-merging. */
2964 197241 : gcc_assert (mode & CLEANUP_CROSSJUMP);
2965 197241 : df_analyze ();
2966 : }
2967 :
2968 25622472 : if (changed)
2969 : {
2970 : /* Edge forwarding in particular can cause hot blocks previously
2971 : reached by both hot and cold blocks to become dominated only
2972 : by cold blocks. This will cause the verification below to fail,
2973 : and lead to now cold code in the hot section. This is not easy
2974 : to detect and fix during edge forwarding, and in some cases
2975 : is only visible after newly unreachable blocks are deleted,
2976 : which will be done in fixup_partitions. */
2977 3845072 : if ((mode & CLEANUP_NO_PARTITIONING) == 0)
2978 : {
2979 3707842 : fixup_partitions ();
2980 3707842 : checking_verify_flow_info ();
2981 : }
2982 : }
2983 :
2984 25622472 : changed_overall |= changed;
2985 25622472 : first_pass = false;
2986 : }
2987 : while (changed);
2988 : }
2989 :
2990 351699146 : FOR_ALL_BB_FN (b, cfun)
2991 329921746 : b->flags &= ~(BB_FORWARDER_BLOCK | BB_NONTHREADABLE_BLOCK);
2992 :
2993 21777400 : return changed_overall;
2994 : }
2995 :
2996 : /* Delete all unreachable basic blocks. */
2997 :
2998 : bool
2999 28097858 : delete_unreachable_blocks (void)
3000 : {
3001 28097858 : bool changed = false;
3002 28097858 : basic_block b, prev_bb;
3003 :
3004 28097858 : find_unreachable_blocks ();
3005 :
3006 : /* When we're in GIMPLE mode and there may be debug bind insns, we
3007 : should delete blocks in reverse dominator order, so as to get a
3008 : chance to substitute all released DEFs into debug bind stmts. If
3009 : we don't have dominators information, walking blocks backward
3010 : gets us a better chance of retaining most debug information than
3011 : otherwise. */
3012 12624852 : if (MAY_HAVE_DEBUG_BIND_INSNS && current_ir_type () == IR_GIMPLE
3013 28346896 : && dom_info_available_p (CDI_DOMINATORS))
3014 : {
3015 0 : for (b = EXIT_BLOCK_PTR_FOR_FN (cfun)->prev_bb;
3016 0 : b != ENTRY_BLOCK_PTR_FOR_FN (cfun); b = prev_bb)
3017 : {
3018 0 : prev_bb = b->prev_bb;
3019 :
3020 0 : if (!(b->flags & BB_REACHABLE))
3021 : {
3022 : /* Speed up the removal of blocks that don't dominate
3023 : others. Walking backwards, this should be the common
3024 : case. */
3025 0 : if (!first_dom_son (CDI_DOMINATORS, b))
3026 0 : delete_basic_block (b);
3027 : else
3028 : {
3029 0 : auto_vec<basic_block> h
3030 0 : = get_all_dominated_blocks (CDI_DOMINATORS, b);
3031 :
3032 0 : while (h.length ())
3033 : {
3034 0 : b = h.pop ();
3035 :
3036 0 : prev_bb = b->prev_bb;
3037 :
3038 0 : gcc_assert (!(b->flags & BB_REACHABLE));
3039 :
3040 0 : delete_basic_block (b);
3041 : }
3042 0 : }
3043 :
3044 : changed = true;
3045 : }
3046 : }
3047 : }
3048 : else
3049 : {
3050 28097858 : for (b = EXIT_BLOCK_PTR_FOR_FN (cfun)->prev_bb;
3051 416568139 : b != ENTRY_BLOCK_PTR_FOR_FN (cfun); b = prev_bb)
3052 : {
3053 388470281 : prev_bb = b->prev_bb;
3054 :
3055 388470281 : if (!(b->flags & BB_REACHABLE))
3056 : {
3057 1607476 : delete_basic_block (b);
3058 1607476 : changed = true;
3059 : }
3060 : }
3061 : }
3062 :
3063 28097858 : if (changed)
3064 434616 : tidy_fallthru_edges ();
3065 28097858 : return changed;
3066 : }
3067 :
3068 : /* Delete any jump tables never referenced. We can't delete them at the
3069 : time of removing tablejump insn as they are referenced by the preceding
3070 : insns computing the destination, so we delay deleting and garbagecollect
3071 : them once life information is computed. */
3072 : void
3073 9123235 : delete_dead_jumptables (void)
3074 : {
3075 9123235 : basic_block bb;
3076 :
3077 : /* A dead jump table does not belong to any basic block. Scan insns
3078 : between two adjacent basic blocks. */
3079 101693409 : FOR_EACH_BB_FN (bb, cfun)
3080 : {
3081 92570174 : rtx_insn *insn, *next;
3082 :
3083 92570174 : for (insn = NEXT_INSN (BB_END (bb));
3084 169289649 : insn && !NOTE_INSN_BASIC_BLOCK_P (insn);
3085 : insn = next)
3086 : {
3087 76719475 : next = NEXT_INSN (insn);
3088 76719475 : if (LABEL_P (insn)
3089 43537550 : && LABEL_NUSES (insn) == LABEL_PRESERVE_P (insn)
3090 78533171 : && JUMP_TABLE_DATA_P (next))
3091 : {
3092 0 : rtx_insn *label = insn, *jump = next;
3093 :
3094 0 : if (dump_file)
3095 0 : fprintf (dump_file, "Dead jumptable %i removed\n",
3096 0 : INSN_UID (insn));
3097 :
3098 0 : next = NEXT_INSN (next);
3099 0 : delete_insn (jump);
3100 0 : delete_insn (label);
3101 : }
3102 : }
3103 : }
3104 9123235 : }
3105 :
3106 :
3107 : /* Tidy the CFG by deleting unreachable code and whatnot. */
3108 :
3109 : bool
3110 19613425 : cleanup_cfg (int mode)
3111 : {
3112 19613425 : bool changed = false;
3113 :
3114 : /* Set the cfglayout mode flag here. We could update all the callers
3115 : but that is just inconvenient, especially given that we eventually
3116 : want to have cfglayout mode as the default. */
3117 19613425 : if (current_ir_type () == IR_RTL_CFGLAYOUT)
3118 13011675 : mode |= CLEANUP_CFGLAYOUT;
3119 :
3120 19613425 : timevar_push (TV_CLEANUP_CFG);
3121 19613425 : if (delete_unreachable_blocks ())
3122 : {
3123 153204 : changed = true;
3124 : /* We've possibly created trivially dead code. Cleanup it right
3125 : now to introduce more opportunities for try_optimize_cfg. */
3126 153204 : if (!(mode & (CLEANUP_NO_INSN_DEL))
3127 41755 : && !reload_completed)
3128 41692 : delete_trivially_dead_insns (get_insns (), max_reg_num ());
3129 : }
3130 :
3131 19613425 : compact_blocks ();
3132 :
3133 : /* To tail-merge blocks ending in the same noreturn function (e.g.
3134 : a call to abort) we have to insert fake edges to exit. Do this
3135 : here once. The fake edges do not interfere with any other CFG
3136 : cleanups. */
3137 19613425 : if (mode & CLEANUP_CROSSJUMP)
3138 960355 : add_noreturn_fake_exit_edges ();
3139 :
3140 19613425 : if (!dbg_cnt (cfg_cleanup))
3141 : return changed;
3142 :
3143 21777400 : while (try_optimize_cfg (mode))
3144 : {
3145 3755374 : delete_unreachable_blocks (), changed = true;
3146 3755374 : if (!(mode & CLEANUP_NO_INSN_DEL))
3147 : {
3148 : /* Try to remove some trivially dead insns when doing an expensive
3149 : cleanup. But delete_trivially_dead_insns doesn't work after
3150 : reload (it only handles pseudos) and run_fast_dce is too costly
3151 : to run in every iteration.
3152 :
3153 : For effective cross jumping, we really want to run a fast DCE to
3154 : clean up any dead conditions, or they get in the way of performing
3155 : useful tail merges.
3156 :
3157 : Other transformations in cleanup_cfg are not so sensitive to dead
3158 : code, so delete_trivially_dead_insns or even doing nothing at all
3159 : is good enough. */
3160 634986 : if ((mode & CLEANUP_EXPENSIVE) && !reload_completed
3161 2232688 : && !delete_trivially_dead_insns (get_insns (), max_reg_num ()))
3162 : break;
3163 2163975 : if ((mode & CLEANUP_CROSSJUMP) && crossjumps_occurred)
3164 : {
3165 81099 : run_fast_dce ();
3166 81099 : mode &= ~CLEANUP_FORCE_FAST_DCE;
3167 : }
3168 : }
3169 : else
3170 : break;
3171 : }
3172 :
3173 19613425 : if (mode & CLEANUP_CROSSJUMP)
3174 960355 : remove_fake_exit_edges ();
3175 :
3176 19613425 : if (mode & CLEANUP_FORCE_FAST_DCE)
3177 115636 : run_fast_dce ();
3178 :
3179 : /* Don't call delete_dead_jumptables in cfglayout mode, because
3180 : that function assumes that jump tables are in the insns stream.
3181 : But we also don't _have_ to delete dead jumptables in cfglayout
3182 : mode because we shouldn't even be looking at things that are
3183 : not in a basic block. Dead jumptables are cleaned up when
3184 : going out of cfglayout mode. */
3185 19613425 : if (!(mode & CLEANUP_CFGLAYOUT))
3186 6601750 : delete_dead_jumptables ();
3187 :
3188 : /* ??? We probably do this way too often. */
3189 19613425 : if (current_loops
3190 9142667 : && (changed
3191 6742047 : || (mode & CLEANUP_CFG_CHANGED)))
3192 : {
3193 2491476 : timevar_push (TV_REPAIR_LOOPS);
3194 : /* The above doesn't preserve dominance info if available. */
3195 2491476 : gcc_assert (!dom_info_available_p (CDI_DOMINATORS));
3196 2491476 : calculate_dominance_info (CDI_DOMINATORS);
3197 2491476 : fix_loop_structure (NULL);
3198 2491476 : free_dominance_info (CDI_DOMINATORS);
3199 2491476 : timevar_pop (TV_REPAIR_LOOPS);
3200 : }
3201 :
3202 19613425 : timevar_pop (TV_CLEANUP_CFG);
3203 :
3204 19613425 : return changed;
3205 : }
3206 :
3207 : namespace {
3208 :
3209 : const pass_data pass_data_jump =
3210 : {
3211 : RTL_PASS, /* type */
3212 : "jump", /* name */
3213 : OPTGROUP_NONE, /* optinfo_flags */
3214 : TV_JUMP, /* tv_id */
3215 : 0, /* properties_required */
3216 : 0, /* properties_provided */
3217 : 0, /* properties_destroyed */
3218 : 0, /* todo_flags_start */
3219 : 0, /* todo_flags_finish */
3220 : };
3221 :
3222 : class pass_jump : public rtl_opt_pass
3223 : {
3224 : public:
3225 287872 : pass_jump (gcc::context *ctxt)
3226 575744 : : rtl_opt_pass (pass_data_jump, ctxt)
3227 : {}
3228 :
3229 : /* opt_pass methods: */
3230 : unsigned int execute (function *) final override;
3231 :
3232 : }; // class pass_jump
3233 :
3234 : unsigned int
3235 1480944 : pass_jump::execute (function *)
3236 : {
3237 1480944 : delete_trivially_dead_insns (get_insns (), max_reg_num ());
3238 1480944 : if (dump_file)
3239 84 : dump_flow_info (dump_file, dump_flags);
3240 2961888 : cleanup_cfg ((optimize ? CLEANUP_EXPENSIVE : 0)
3241 1040108 : | (flag_thread_jumps && flag_expensive_optimizations
3242 1480944 : ? CLEANUP_THREADING : 0));
3243 1480944 : return 0;
3244 : }
3245 :
3246 : } // anon namespace
3247 :
3248 : rtl_opt_pass *
3249 287872 : make_pass_jump (gcc::context *ctxt)
3250 : {
3251 287872 : return new pass_jump (ctxt);
3252 : }
3253 :
3254 : namespace {
3255 :
3256 : const pass_data pass_data_jump_after_combine =
3257 : {
3258 : RTL_PASS, /* type */
3259 : "jump_after_combine", /* name */
3260 : OPTGROUP_NONE, /* optinfo_flags */
3261 : TV_JUMP, /* tv_id */
3262 : 0, /* properties_required */
3263 : 0, /* properties_provided */
3264 : 0, /* properties_destroyed */
3265 : 0, /* todo_flags_start */
3266 : 0, /* todo_flags_finish */
3267 : };
3268 :
3269 : class pass_jump_after_combine : public rtl_opt_pass
3270 : {
3271 : public:
3272 287872 : pass_jump_after_combine (gcc::context *ctxt)
3273 575744 : : rtl_opt_pass (pass_data_jump_after_combine, ctxt)
3274 : {}
3275 :
3276 : /* opt_pass methods: */
3277 1480955 : bool gate (function *) final override
3278 : {
3279 1480955 : return flag_thread_jumps && flag_expensive_optimizations;
3280 : }
3281 : unsigned int execute (function *) final override;
3282 :
3283 : }; // class pass_jump_after_combine
3284 :
3285 : unsigned int
3286 960210 : pass_jump_after_combine::execute (function *)
3287 : {
3288 : /* Jump threading does not keep dominators up-to-date. */
3289 960210 : free_dominance_info (CDI_DOMINATORS);
3290 960210 : cleanup_cfg (CLEANUP_THREADING);
3291 960210 : return 0;
3292 : }
3293 :
3294 : } // anon namespace
3295 :
3296 : rtl_opt_pass *
3297 287872 : make_pass_jump_after_combine (gcc::context *ctxt)
3298 : {
3299 287872 : return new pass_jump_after_combine (ctxt);
3300 : }
3301 :
3302 : namespace {
3303 :
3304 : const pass_data pass_data_jump2 =
3305 : {
3306 : RTL_PASS, /* type */
3307 : "jump2", /* name */
3308 : OPTGROUP_NONE, /* optinfo_flags */
3309 : TV_JUMP, /* tv_id */
3310 : 0, /* properties_required */
3311 : 0, /* properties_provided */
3312 : 0, /* properties_destroyed */
3313 : 0, /* todo_flags_start */
3314 : 0, /* todo_flags_finish */
3315 : };
3316 :
3317 : class pass_jump2 : public rtl_opt_pass
3318 : {
3319 : public:
3320 287872 : pass_jump2 (gcc::context *ctxt)
3321 575744 : : rtl_opt_pass (pass_data_jump2, ctxt)
3322 : {}
3323 :
3324 : /* opt_pass methods: */
3325 1480948 : unsigned int execute (function *) final override
3326 : {
3327 2001541 : cleanup_cfg (flag_crossjumping ? CLEANUP_CROSSJUMP : 0);
3328 1480948 : return 0;
3329 : }
3330 :
3331 : }; // class pass_jump2
3332 :
3333 : } // anon namespace
3334 :
3335 : rtl_opt_pass *
3336 287872 : make_pass_jump2 (gcc::context *ctxt)
3337 : {
3338 287872 : return new pass_jump2 (ctxt);
3339 : }
|
