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1 | /* Natural loop discovery code for GNU compiler. | |
2 | Copyright (C) 2000, 2001, 2003, 2004, 2005, 2006, 2007, 2008, 2010 | |
3 | Free Software Foundation, Inc. | |
4 | ||
5 | This file is part of GCC. | |
6 | ||
7 | GCC is free software; you can redistribute it and/or modify it under | |
8 | the terms of the GNU General Public License as published by the Free | |
9 | Software Foundation; either version 3, or (at your option) any later | |
10 | version. | |
11 | ||
12 | GCC is distributed in the hope that it will be useful, but WITHOUT ANY | |
13 | WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
14 | FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
15 | for more details. | |
16 | ||
17 | You should have received a copy of the GNU General Public License | |
18 | along with GCC; see the file COPYING3. If not see | |
19 | <http://www.gnu.org/licenses/>. */ | |
20 | ||
21 | #include "config.h" | |
22 | #include "system.h" | |
23 | #include "coretypes.h" | |
24 | #include "tm.h" | |
25 | #include "rtl.h" | |
26 | #include "function.h" | |
27 | #include "basic-block.h" | |
28 | #include "cfgloop.h" | |
29 | #include "diagnostic-core.h" | |
30 | #include "flags.h" | |
31 | #include "tree.h" | |
32 | #include "tree-flow.h" | |
33 | #include "pointer-set.h" | |
34 | #include "ggc.h" | |
35 | #include "dumpfile.h" | |
36 | ||
37 | static void flow_loops_cfg_dump (FILE *); | |
38 | \f | |
39 | /* Dump loop related CFG information. */ | |
40 | ||
41 | static void | |
42 | flow_loops_cfg_dump (FILE *file) | |
43 | { | |
44 | basic_block bb; | |
45 | ||
46 | if (!file) | |
47 | return; | |
48 | ||
49 | FOR_EACH_BB (bb) | |
50 | { | |
51 | edge succ; | |
52 | edge_iterator ei; | |
53 | ||
54 | fprintf (file, ";; %d succs { ", bb->index); | |
55 | FOR_EACH_EDGE (succ, ei, bb->succs) | |
56 | fprintf (file, "%d ", succ->dest->index); | |
57 | fprintf (file, "}\n"); | |
58 | } | |
59 | } | |
60 | ||
61 | /* Return nonzero if the nodes of LOOP are a subset of OUTER. */ | |
62 | ||
63 | bool | |
64 | flow_loop_nested_p (const struct loop *outer, const struct loop *loop) | |
65 | { | |
66 | unsigned odepth = loop_depth (outer); | |
67 | ||
68 | return (loop_depth (loop) > odepth | |
69 | && (*loop->superloops)[odepth] == outer); | |
70 | } | |
71 | ||
72 | /* Returns the loop such that LOOP is nested DEPTH (indexed from zero) | |
73 | loops within LOOP. */ | |
74 | ||
75 | struct loop * | |
76 | superloop_at_depth (struct loop *loop, unsigned depth) | |
77 | { | |
78 | unsigned ldepth = loop_depth (loop); | |
79 | ||
80 | gcc_assert (depth <= ldepth); | |
81 | ||
82 | if (depth == ldepth) | |
83 | return loop; | |
84 | ||
85 | return (*loop->superloops)[depth]; | |
86 | } | |
87 | ||
88 | /* Returns the list of the latch edges of LOOP. */ | |
89 | ||
90 | static vec<edge> | |
91 | get_loop_latch_edges (const struct loop *loop) | |
92 | { | |
93 | edge_iterator ei; | |
94 | edge e; | |
95 | vec<edge> ret = vNULL; | |
96 | ||
97 | FOR_EACH_EDGE (e, ei, loop->header->preds) | |
98 | { | |
99 | if (dominated_by_p (CDI_DOMINATORS, e->src, loop->header)) | |
100 | ret.safe_push (e); | |
101 | } | |
102 | ||
103 | return ret; | |
104 | } | |
105 | ||
106 | /* Dump the loop information specified by LOOP to the stream FILE | |
107 | using auxiliary dump callback function LOOP_DUMP_AUX if non null. */ | |
108 | ||
109 | void | |
110 | flow_loop_dump (const struct loop *loop, FILE *file, | |
111 | void (*loop_dump_aux) (const struct loop *, FILE *, int), | |
112 | int verbose) | |
113 | { | |
114 | basic_block *bbs; | |
115 | unsigned i; | |
116 | vec<edge> latches; | |
117 | edge e; | |
118 | ||
119 | if (! loop || ! loop->header) | |
120 | return; | |
121 | ||
122 | fprintf (file, ";;\n;; Loop %d\n", loop->num); | |
123 | ||
124 | fprintf (file, ";; header %d, ", loop->header->index); | |
125 | if (loop->latch) | |
126 | fprintf (file, "latch %d\n", loop->latch->index); | |
127 | else | |
128 | { | |
129 | fprintf (file, "multiple latches:"); | |
130 | latches = get_loop_latch_edges (loop); | |
131 | FOR_EACH_VEC_ELT (latches, i, e) | |
132 | fprintf (file, " %d", e->src->index); | |
133 | latches.release (); | |
134 | fprintf (file, "\n"); | |
135 | } | |
136 | ||
137 | fprintf (file, ";; depth %d, outer %ld\n", | |
138 | loop_depth (loop), (long) (loop_outer (loop) | |
139 | ? loop_outer (loop)->num : -1)); | |
140 | ||
141 | fprintf (file, ";; nodes:"); | |
142 | bbs = get_loop_body (loop); | |
143 | for (i = 0; i < loop->num_nodes; i++) | |
144 | fprintf (file, " %d", bbs[i]->index); | |
145 | free (bbs); | |
146 | fprintf (file, "\n"); | |
147 | ||
148 | if (loop_dump_aux) | |
149 | loop_dump_aux (loop, file, verbose); | |
150 | } | |
151 | ||
152 | /* Dump the loop information about loops to the stream FILE, | |
153 | using auxiliary dump callback function LOOP_DUMP_AUX if non null. */ | |
154 | ||
155 | void | |
156 | flow_loops_dump (FILE *file, void (*loop_dump_aux) (const struct loop *, FILE *, int), int verbose) | |
157 | { | |
158 | loop_iterator li; | |
159 | struct loop *loop; | |
160 | ||
161 | if (!current_loops || ! file) | |
162 | return; | |
163 | ||
164 | fprintf (file, ";; %d loops found\n", number_of_loops ()); | |
165 | ||
166 | FOR_EACH_LOOP (li, loop, LI_INCLUDE_ROOT) | |
167 | { | |
168 | flow_loop_dump (loop, file, loop_dump_aux, verbose); | |
169 | } | |
170 | ||
171 | if (verbose) | |
172 | flow_loops_cfg_dump (file); | |
173 | } | |
174 | ||
175 | /* Free data allocated for LOOP. */ | |
176 | ||
177 | void | |
178 | flow_loop_free (struct loop *loop) | |
179 | { | |
180 | struct loop_exit *exit, *next; | |
181 | ||
182 | vec_free (loop->superloops); | |
183 | ||
184 | /* Break the list of the loop exit records. They will be freed when the | |
185 | corresponding edge is rescanned or removed, and this avoids | |
186 | accessing the (already released) head of the list stored in the | |
187 | loop structure. */ | |
188 | for (exit = loop->exits->next; exit != loop->exits; exit = next) | |
189 | { | |
190 | next = exit->next; | |
191 | exit->next = exit; | |
192 | exit->prev = exit; | |
193 | } | |
194 | ||
195 | ggc_free (loop->exits); | |
196 | ggc_free (loop); | |
197 | } | |
198 | ||
199 | /* Free all the memory allocated for LOOPS. */ | |
200 | ||
201 | void | |
202 | flow_loops_free (struct loops *loops) | |
203 | { | |
204 | if (loops->larray) | |
205 | { | |
206 | unsigned i; | |
207 | loop_p loop; | |
208 | ||
209 | /* Free the loop descriptors. */ | |
210 | FOR_EACH_VEC_SAFE_ELT (loops->larray, i, loop) | |
211 | { | |
212 | if (!loop) | |
213 | continue; | |
214 | ||
215 | flow_loop_free (loop); | |
216 | } | |
217 | ||
218 | vec_free (loops->larray); | |
219 | } | |
220 | } | |
221 | ||
222 | /* Find the nodes contained within the LOOP with header HEADER. | |
223 | Return the number of nodes within the loop. */ | |
224 | ||
225 | int | |
226 | flow_loop_nodes_find (basic_block header, struct loop *loop) | |
227 | { | |
228 | vec<basic_block> stack = vNULL; | |
229 | int num_nodes = 1; | |
230 | edge latch; | |
231 | edge_iterator latch_ei; | |
232 | ||
233 | header->loop_father = loop; | |
234 | ||
235 | FOR_EACH_EDGE (latch, latch_ei, loop->header->preds) | |
236 | { | |
237 | if (latch->src->loop_father == loop | |
238 | || !dominated_by_p (CDI_DOMINATORS, latch->src, loop->header)) | |
239 | continue; | |
240 | ||
241 | num_nodes++; | |
242 | stack.safe_push (latch->src); | |
243 | latch->src->loop_father = loop; | |
244 | ||
245 | while (!stack.is_empty ()) | |
246 | { | |
247 | basic_block node; | |
248 | edge e; | |
249 | edge_iterator ei; | |
250 | ||
251 | node = stack.pop (); | |
252 | ||
253 | FOR_EACH_EDGE (e, ei, node->preds) | |
254 | { | |
255 | basic_block ancestor = e->src; | |
256 | ||
257 | if (ancestor->loop_father != loop) | |
258 | { | |
259 | ancestor->loop_father = loop; | |
260 | num_nodes++; | |
261 | stack.safe_push (ancestor); | |
262 | } | |
263 | } | |
264 | } | |
265 | } | |
266 | stack.release (); | |
267 | ||
268 | return num_nodes; | |
269 | } | |
270 | ||
271 | /* Records the vector of superloops of the loop LOOP, whose immediate | |
272 | superloop is FATHER. */ | |
273 | ||
274 | static void | |
275 | establish_preds (struct loop *loop, struct loop *father) | |
276 | { | |
277 | loop_p ploop; | |
278 | unsigned depth = loop_depth (father) + 1; | |
279 | unsigned i; | |
280 | ||
281 | loop->superloops = 0; | |
282 | vec_alloc (loop->superloops, depth); | |
283 | FOR_EACH_VEC_SAFE_ELT (father->superloops, i, ploop) | |
284 | loop->superloops->quick_push (ploop); | |
285 | loop->superloops->quick_push (father); | |
286 | ||
287 | for (ploop = loop->inner; ploop; ploop = ploop->next) | |
288 | establish_preds (ploop, loop); | |
289 | } | |
290 | ||
291 | /* Add LOOP to the loop hierarchy tree where FATHER is father of the | |
292 | added loop. If LOOP has some children, take care of that their | |
293 | pred field will be initialized correctly. */ | |
294 | ||
295 | void | |
296 | flow_loop_tree_node_add (struct loop *father, struct loop *loop) | |
297 | { | |
298 | loop->next = father->inner; | |
299 | father->inner = loop; | |
300 | ||
301 | establish_preds (loop, father); | |
302 | } | |
303 | ||
304 | /* Remove LOOP from the loop hierarchy tree. */ | |
305 | ||
306 | void | |
307 | flow_loop_tree_node_remove (struct loop *loop) | |
308 | { | |
309 | struct loop *prev, *father; | |
310 | ||
311 | father = loop_outer (loop); | |
312 | ||
313 | /* Remove loop from the list of sons. */ | |
314 | if (father->inner == loop) | |
315 | father->inner = loop->next; | |
316 | else | |
317 | { | |
318 | for (prev = father->inner; prev->next != loop; prev = prev->next) | |
319 | continue; | |
320 | prev->next = loop->next; | |
321 | } | |
322 | ||
323 | loop->superloops = NULL; | |
324 | } | |
325 | ||
326 | /* Allocates and returns new loop structure. */ | |
327 | ||
328 | struct loop * | |
329 | alloc_loop (void) | |
330 | { | |
331 | struct loop *loop = ggc_alloc_cleared_loop (); | |
332 | ||
333 | loop->exits = ggc_alloc_cleared_loop_exit (); | |
334 | loop->exits->next = loop->exits->prev = loop->exits; | |
335 | loop->can_be_parallel = false; | |
336 | ||
337 | return loop; | |
338 | } | |
339 | ||
340 | /* Initializes loops structure LOOPS, reserving place for NUM_LOOPS loops | |
341 | (including the root of the loop tree). */ | |
342 | ||
343 | static void | |
344 | init_loops_structure (struct loops *loops, unsigned num_loops) | |
345 | { | |
346 | struct loop *root; | |
347 | ||
348 | memset (loops, 0, sizeof *loops); | |
349 | vec_alloc (loops->larray, num_loops); | |
350 | ||
351 | /* Dummy loop containing whole function. */ | |
352 | root = alloc_loop (); | |
353 | root->num_nodes = n_basic_blocks; | |
354 | root->latch = EXIT_BLOCK_PTR; | |
355 | root->header = ENTRY_BLOCK_PTR; | |
356 | ENTRY_BLOCK_PTR->loop_father = root; | |
357 | EXIT_BLOCK_PTR->loop_father = root; | |
358 | ||
359 | loops->larray->quick_push (root); | |
360 | loops->tree_root = root; | |
361 | } | |
362 | ||
363 | /* Find all the natural loops in the function and save in LOOPS structure and | |
364 | recalculate loop_father information in basic block structures. | |
365 | Return the number of natural loops found. */ | |
366 | ||
367 | int | |
368 | flow_loops_find (struct loops *loops) | |
369 | { | |
370 | int b; | |
371 | int num_loops; | |
372 | edge e; | |
373 | sbitmap headers; | |
374 | int *dfs_order; | |
375 | int *rc_order; | |
376 | basic_block header; | |
377 | basic_block bb; | |
378 | ||
379 | /* Ensure that the dominators are computed. */ | |
380 | calculate_dominance_info (CDI_DOMINATORS); | |
381 | ||
382 | /* Taking care of this degenerate case makes the rest of | |
383 | this code simpler. */ | |
384 | if (n_basic_blocks == NUM_FIXED_BLOCKS) | |
385 | { | |
386 | init_loops_structure (loops, 1); | |
387 | return 1; | |
388 | } | |
389 | ||
390 | dfs_order = NULL; | |
391 | rc_order = NULL; | |
392 | ||
393 | /* Count the number of loop headers. This should be the | |
394 | same as the number of natural loops. */ | |
395 | headers = sbitmap_alloc (last_basic_block); | |
396 | bitmap_clear (headers); | |
397 | ||
398 | num_loops = 0; | |
399 | FOR_EACH_BB (header) | |
400 | { | |
401 | edge_iterator ei; | |
402 | ||
403 | /* If we have an abnormal predecessor, do not consider the | |
404 | loop (not worth the problems). */ | |
405 | if (bb_has_abnormal_pred (header)) | |
406 | continue; | |
407 | ||
408 | FOR_EACH_EDGE (e, ei, header->preds) | |
409 | { | |
410 | basic_block latch = e->src; | |
411 | ||
412 | gcc_assert (!(e->flags & EDGE_ABNORMAL)); | |
413 | ||
414 | /* Look for back edges where a predecessor is dominated | |
415 | by this block. A natural loop has a single entry | |
416 | node (header) that dominates all the nodes in the | |
417 | loop. It also has single back edge to the header | |
418 | from a latch node. */ | |
419 | if (latch != ENTRY_BLOCK_PTR | |
420 | && dominated_by_p (CDI_DOMINATORS, latch, header)) | |
421 | { | |
422 | /* Shared headers should be eliminated by now. */ | |
423 | bitmap_set_bit (headers, header->index); | |
424 | num_loops++; | |
425 | } | |
426 | } | |
427 | } | |
428 | ||
429 | /* Allocate loop structures. */ | |
430 | init_loops_structure (loops, num_loops + 1); | |
431 | ||
432 | /* Find and record information about all the natural loops | |
433 | in the CFG. */ | |
434 | FOR_EACH_BB (bb) | |
435 | bb->loop_father = loops->tree_root; | |
436 | ||
437 | if (num_loops) | |
438 | { | |
439 | /* Compute depth first search order of the CFG so that outer | |
440 | natural loops will be found before inner natural loops. */ | |
441 | dfs_order = XNEWVEC (int, n_basic_blocks); | |
442 | rc_order = XNEWVEC (int, n_basic_blocks); | |
443 | pre_and_rev_post_order_compute (dfs_order, rc_order, false); | |
444 | ||
445 | num_loops = 1; | |
446 | ||
447 | for (b = 0; b < n_basic_blocks - NUM_FIXED_BLOCKS; b++) | |
448 | { | |
449 | struct loop *loop; | |
450 | edge_iterator ei; | |
451 | ||
452 | /* Search the nodes of the CFG in reverse completion order | |
453 | so that we can find outer loops first. */ | |
454 | if (!bitmap_bit_p (headers, rc_order[b])) | |
455 | continue; | |
456 | ||
457 | header = BASIC_BLOCK (rc_order[b]); | |
458 | ||
459 | loop = alloc_loop (); | |
460 | loops->larray->quick_push (loop); | |
461 | ||
462 | loop->header = header; | |
463 | loop->num = num_loops; | |
464 | num_loops++; | |
465 | ||
466 | flow_loop_tree_node_add (header->loop_father, loop); | |
467 | loop->num_nodes = flow_loop_nodes_find (loop->header, loop); | |
468 | ||
469 | /* Look for the latch for this header block, if it has just a | |
470 | single one. */ | |
471 | FOR_EACH_EDGE (e, ei, header->preds) | |
472 | { | |
473 | basic_block latch = e->src; | |
474 | ||
475 | if (flow_bb_inside_loop_p (loop, latch)) | |
476 | { | |
477 | if (loop->latch != NULL) | |
478 | { | |
479 | /* More than one latch edge. */ | |
480 | loop->latch = NULL; | |
481 | break; | |
482 | } | |
483 | loop->latch = latch; | |
484 | } | |
485 | } | |
486 | } | |
487 | ||
488 | free (dfs_order); | |
489 | free (rc_order); | |
490 | } | |
491 | ||
492 | sbitmap_free (headers); | |
493 | ||
494 | loops->exits = NULL; | |
495 | return loops->larray->length (); | |
496 | } | |
497 | ||
498 | /* Ratio of frequencies of edges so that one of more latch edges is | |
499 | considered to belong to inner loop with same header. */ | |
500 | #define HEAVY_EDGE_RATIO 8 | |
501 | ||
502 | /* Minimum number of samples for that we apply | |
503 | find_subloop_latch_edge_by_profile heuristics. */ | |
504 | #define HEAVY_EDGE_MIN_SAMPLES 10 | |
505 | ||
506 | /* If the profile info is available, finds an edge in LATCHES that much more | |
507 | frequent than the remaining edges. Returns such an edge, or NULL if we do | |
508 | not find one. | |
509 | ||
510 | We do not use guessed profile here, only the measured one. The guessed | |
511 | profile is usually too flat and unreliable for this (and it is mostly based | |
512 | on the loop structure of the program, so it does not make much sense to | |
513 | derive the loop structure from it). */ | |
514 | ||
515 | static edge | |
516 | find_subloop_latch_edge_by_profile (vec<edge> latches) | |
517 | { | |
518 | unsigned i; | |
519 | edge e, me = NULL; | |
520 | gcov_type mcount = 0, tcount = 0; | |
521 | ||
522 | FOR_EACH_VEC_ELT (latches, i, e) | |
523 | { | |
524 | if (e->count > mcount) | |
525 | { | |
526 | me = e; | |
527 | mcount = e->count; | |
528 | } | |
529 | tcount += e->count; | |
530 | } | |
531 | ||
532 | if (tcount < HEAVY_EDGE_MIN_SAMPLES | |
533 | || (tcount - mcount) * HEAVY_EDGE_RATIO > tcount) | |
534 | return NULL; | |
535 | ||
536 | if (dump_file) | |
537 | fprintf (dump_file, | |
538 | "Found latch edge %d -> %d using profile information.\n", | |
539 | me->src->index, me->dest->index); | |
540 | return me; | |
541 | } | |
542 | ||
543 | /* Among LATCHES, guesses a latch edge of LOOP corresponding to subloop, based | |
544 | on the structure of induction variables. Returns this edge, or NULL if we | |
545 | do not find any. | |
546 | ||
547 | We are quite conservative, and look just for an obvious simple innermost | |
548 | loop (which is the case where we would lose the most performance by not | |
549 | disambiguating the loop). More precisely, we look for the following | |
550 | situation: The source of the chosen latch edge dominates sources of all | |
551 | the other latch edges. Additionally, the header does not contain a phi node | |
552 | such that the argument from the chosen edge is equal to the argument from | |
553 | another edge. */ | |
554 | ||
555 | static edge | |
556 | find_subloop_latch_edge_by_ivs (struct loop *loop ATTRIBUTE_UNUSED, vec<edge> latches) | |
557 | { | |
558 | edge e, latch = latches[0]; | |
559 | unsigned i; | |
560 | gimple phi; | |
561 | gimple_stmt_iterator psi; | |
562 | tree lop; | |
563 | basic_block bb; | |
564 | ||
565 | /* Find the candidate for the latch edge. */ | |
566 | for (i = 1; latches.iterate (i, &e); i++) | |
567 | if (dominated_by_p (CDI_DOMINATORS, latch->src, e->src)) | |
568 | latch = e; | |
569 | ||
570 | /* Verify that it dominates all the latch edges. */ | |
571 | FOR_EACH_VEC_ELT (latches, i, e) | |
572 | if (!dominated_by_p (CDI_DOMINATORS, e->src, latch->src)) | |
573 | return NULL; | |
574 | ||
575 | /* Check for a phi node that would deny that this is a latch edge of | |
576 | a subloop. */ | |
577 | for (psi = gsi_start_phis (loop->header); !gsi_end_p (psi); gsi_next (&psi)) | |
578 | { | |
579 | phi = gsi_stmt (psi); | |
580 | lop = PHI_ARG_DEF_FROM_EDGE (phi, latch); | |
581 | ||
582 | /* Ignore the values that are not changed inside the subloop. */ | |
583 | if (TREE_CODE (lop) != SSA_NAME | |
584 | || SSA_NAME_DEF_STMT (lop) == phi) | |
585 | continue; | |
586 | bb = gimple_bb (SSA_NAME_DEF_STMT (lop)); | |
587 | if (!bb || !flow_bb_inside_loop_p (loop, bb)) | |
588 | continue; | |
589 | ||
590 | FOR_EACH_VEC_ELT (latches, i, e) | |
591 | if (e != latch | |
592 | && PHI_ARG_DEF_FROM_EDGE (phi, e) == lop) | |
593 | return NULL; | |
594 | } | |
595 | ||
596 | if (dump_file) | |
597 | fprintf (dump_file, | |
598 | "Found latch edge %d -> %d using iv structure.\n", | |
599 | latch->src->index, latch->dest->index); | |
600 | return latch; | |
601 | } | |
602 | ||
603 | /* If we can determine that one of the several latch edges of LOOP behaves | |
604 | as a latch edge of a separate subloop, returns this edge. Otherwise | |
605 | returns NULL. */ | |
606 | ||
607 | static edge | |
608 | find_subloop_latch_edge (struct loop *loop) | |
609 | { | |
610 | vec<edge> latches = get_loop_latch_edges (loop); | |
611 | edge latch = NULL; | |
612 | ||
613 | if (latches.length () > 1) | |
614 | { | |
615 | latch = find_subloop_latch_edge_by_profile (latches); | |
616 | ||
617 | if (!latch | |
618 | /* We consider ivs to guess the latch edge only in SSA. Perhaps we | |
619 | should use cfghook for this, but it is hard to imagine it would | |
620 | be useful elsewhere. */ | |
621 | && current_ir_type () == IR_GIMPLE) | |
622 | latch = find_subloop_latch_edge_by_ivs (loop, latches); | |
623 | } | |
624 | ||
625 | latches.release (); | |
626 | return latch; | |
627 | } | |
628 | ||
629 | /* Callback for make_forwarder_block. Returns true if the edge E is marked | |
630 | in the set MFB_REIS_SET. */ | |
631 | ||
632 | static struct pointer_set_t *mfb_reis_set; | |
633 | static bool | |
634 | mfb_redirect_edges_in_set (edge e) | |
635 | { | |
636 | return pointer_set_contains (mfb_reis_set, e); | |
637 | } | |
638 | ||
639 | /* Creates a subloop of LOOP with latch edge LATCH. */ | |
640 | ||
641 | static void | |
642 | form_subloop (struct loop *loop, edge latch) | |
643 | { | |
644 | edge_iterator ei; | |
645 | edge e, new_entry; | |
646 | struct loop *new_loop; | |
647 | ||
648 | mfb_reis_set = pointer_set_create (); | |
649 | FOR_EACH_EDGE (e, ei, loop->header->preds) | |
650 | { | |
651 | if (e != latch) | |
652 | pointer_set_insert (mfb_reis_set, e); | |
653 | } | |
654 | new_entry = make_forwarder_block (loop->header, mfb_redirect_edges_in_set, | |
655 | NULL); | |
656 | pointer_set_destroy (mfb_reis_set); | |
657 | ||
658 | loop->header = new_entry->src; | |
659 | ||
660 | /* Find the blocks and subloops that belong to the new loop, and add it to | |
661 | the appropriate place in the loop tree. */ | |
662 | new_loop = alloc_loop (); | |
663 | new_loop->header = new_entry->dest; | |
664 | new_loop->latch = latch->src; | |
665 | add_loop (new_loop, loop); | |
666 | } | |
667 | ||
668 | /* Make all the latch edges of LOOP to go to a single forwarder block -- | |
669 | a new latch of LOOP. */ | |
670 | ||
671 | static void | |
672 | merge_latch_edges (struct loop *loop) | |
673 | { | |
674 | vec<edge> latches = get_loop_latch_edges (loop); | |
675 | edge latch, e; | |
676 | unsigned i; | |
677 | ||
678 | gcc_assert (latches.length () > 0); | |
679 | ||
680 | if (latches.length () == 1) | |
681 | loop->latch = latches[0]->src; | |
682 | else | |
683 | { | |
684 | if (dump_file) | |
685 | fprintf (dump_file, "Merged latch edges of loop %d\n", loop->num); | |
686 | ||
687 | mfb_reis_set = pointer_set_create (); | |
688 | FOR_EACH_VEC_ELT (latches, i, e) | |
689 | pointer_set_insert (mfb_reis_set, e); | |
690 | latch = make_forwarder_block (loop->header, mfb_redirect_edges_in_set, | |
691 | NULL); | |
692 | pointer_set_destroy (mfb_reis_set); | |
693 | ||
694 | loop->header = latch->dest; | |
695 | loop->latch = latch->src; | |
696 | } | |
697 | ||
698 | latches.release (); | |
699 | } | |
700 | ||
701 | /* LOOP may have several latch edges. Transform it into (possibly several) | |
702 | loops with single latch edge. */ | |
703 | ||
704 | static void | |
705 | disambiguate_multiple_latches (struct loop *loop) | |
706 | { | |
707 | edge e; | |
708 | ||
709 | /* We eliminate the multiple latches by splitting the header to the forwarder | |
710 | block F and the rest R, and redirecting the edges. There are two cases: | |
711 | ||
712 | 1) If there is a latch edge E that corresponds to a subloop (we guess | |
713 | that based on profile -- if it is taken much more often than the | |
714 | remaining edges; and on trees, using the information about induction | |
715 | variables of the loops), we redirect E to R, all the remaining edges to | |
716 | F, then rescan the loops and try again for the outer loop. | |
717 | 2) If there is no such edge, we redirect all latch edges to F, and the | |
718 | entry edges to R, thus making F the single latch of the loop. */ | |
719 | ||
720 | if (dump_file) | |
721 | fprintf (dump_file, "Disambiguating loop %d with multiple latches\n", | |
722 | loop->num); | |
723 | ||
724 | /* During latch merging, we may need to redirect the entry edges to a new | |
725 | block. This would cause problems if the entry edge was the one from the | |
726 | entry block. To avoid having to handle this case specially, split | |
727 | such entry edge. */ | |
728 | e = find_edge (ENTRY_BLOCK_PTR, loop->header); | |
729 | if (e) | |
730 | split_edge (e); | |
731 | ||
732 | while (1) | |
733 | { | |
734 | e = find_subloop_latch_edge (loop); | |
735 | if (!e) | |
736 | break; | |
737 | ||
738 | form_subloop (loop, e); | |
739 | } | |
740 | ||
741 | merge_latch_edges (loop); | |
742 | } | |
743 | ||
744 | /* Split loops with multiple latch edges. */ | |
745 | ||
746 | void | |
747 | disambiguate_loops_with_multiple_latches (void) | |
748 | { | |
749 | loop_iterator li; | |
750 | struct loop *loop; | |
751 | ||
752 | FOR_EACH_LOOP (li, loop, 0) | |
753 | { | |
754 | if (!loop->latch) | |
755 | disambiguate_multiple_latches (loop); | |
756 | } | |
757 | } | |
758 | ||
759 | /* Return nonzero if basic block BB belongs to LOOP. */ | |
760 | bool | |
761 | flow_bb_inside_loop_p (const struct loop *loop, const_basic_block bb) | |
762 | { | |
763 | struct loop *source_loop; | |
764 | ||
765 | if (bb == ENTRY_BLOCK_PTR || bb == EXIT_BLOCK_PTR) | |
766 | return 0; | |
767 | ||
768 | source_loop = bb->loop_father; | |
769 | return loop == source_loop || flow_loop_nested_p (loop, source_loop); | |
770 | } | |
771 | ||
772 | /* Enumeration predicate for get_loop_body_with_size. */ | |
773 | static bool | |
774 | glb_enum_p (const_basic_block bb, const void *glb_loop) | |
775 | { | |
776 | const struct loop *const loop = (const struct loop *) glb_loop; | |
777 | return (bb != loop->header | |
778 | && dominated_by_p (CDI_DOMINATORS, bb, loop->header)); | |
779 | } | |
780 | ||
781 | /* Gets basic blocks of a LOOP. Header is the 0-th block, rest is in dfs | |
782 | order against direction of edges from latch. Specially, if | |
783 | header != latch, latch is the 1-st block. LOOP cannot be the fake | |
784 | loop tree root, and its size must be at most MAX_SIZE. The blocks | |
785 | in the LOOP body are stored to BODY, and the size of the LOOP is | |
786 | returned. */ | |
787 | ||
788 | unsigned | |
789 | get_loop_body_with_size (const struct loop *loop, basic_block *body, | |
790 | unsigned max_size) | |
791 | { | |
792 | return dfs_enumerate_from (loop->header, 1, glb_enum_p, | |
793 | body, max_size, loop); | |
794 | } | |
795 | ||
796 | /* Gets basic blocks of a LOOP. Header is the 0-th block, rest is in dfs | |
797 | order against direction of edges from latch. Specially, if | |
798 | header != latch, latch is the 1-st block. */ | |
799 | ||
800 | basic_block * | |
801 | get_loop_body (const struct loop *loop) | |
802 | { | |
803 | basic_block *body, bb; | |
804 | unsigned tv = 0; | |
805 | ||
806 | gcc_assert (loop->num_nodes); | |
807 | ||
808 | body = XNEWVEC (basic_block, loop->num_nodes); | |
809 | ||
810 | if (loop->latch == EXIT_BLOCK_PTR) | |
811 | { | |
812 | /* There may be blocks unreachable from EXIT_BLOCK, hence we need to | |
813 | special-case the fake loop that contains the whole function. */ | |
814 | gcc_assert (loop->num_nodes == (unsigned) n_basic_blocks); | |
815 | body[tv++] = loop->header; | |
816 | body[tv++] = EXIT_BLOCK_PTR; | |
817 | FOR_EACH_BB (bb) | |
818 | body[tv++] = bb; | |
819 | } | |
820 | else | |
821 | tv = get_loop_body_with_size (loop, body, loop->num_nodes); | |
822 | ||
823 | gcc_assert (tv == loop->num_nodes); | |
824 | return body; | |
825 | } | |
826 | ||
827 | /* Fills dominance descendants inside LOOP of the basic block BB into | |
828 | array TOVISIT from index *TV. */ | |
829 | ||
830 | static void | |
831 | fill_sons_in_loop (const struct loop *loop, basic_block bb, | |
832 | basic_block *tovisit, int *tv) | |
833 | { | |
834 | basic_block son, postpone = NULL; | |
835 | ||
836 | tovisit[(*tv)++] = bb; | |
837 | for (son = first_dom_son (CDI_DOMINATORS, bb); | |
838 | son; | |
839 | son = next_dom_son (CDI_DOMINATORS, son)) | |
840 | { | |
841 | if (!flow_bb_inside_loop_p (loop, son)) | |
842 | continue; | |
843 | ||
844 | if (dominated_by_p (CDI_DOMINATORS, loop->latch, son)) | |
845 | { | |
846 | postpone = son; | |
847 | continue; | |
848 | } | |
849 | fill_sons_in_loop (loop, son, tovisit, tv); | |
850 | } | |
851 | ||
852 | if (postpone) | |
853 | fill_sons_in_loop (loop, postpone, tovisit, tv); | |
854 | } | |
855 | ||
856 | /* Gets body of a LOOP (that must be different from the outermost loop) | |
857 | sorted by dominance relation. Additionally, if a basic block s dominates | |
858 | the latch, then only blocks dominated by s are be after it. */ | |
859 | ||
860 | basic_block * | |
861 | get_loop_body_in_dom_order (const struct loop *loop) | |
862 | { | |
863 | basic_block *tovisit; | |
864 | int tv; | |
865 | ||
866 | gcc_assert (loop->num_nodes); | |
867 | ||
868 | tovisit = XNEWVEC (basic_block, loop->num_nodes); | |
869 | ||
870 | gcc_assert (loop->latch != EXIT_BLOCK_PTR); | |
871 | ||
872 | tv = 0; | |
873 | fill_sons_in_loop (loop, loop->header, tovisit, &tv); | |
874 | ||
875 | gcc_assert (tv == (int) loop->num_nodes); | |
876 | ||
877 | return tovisit; | |
878 | } | |
879 | ||
880 | /* Gets body of a LOOP sorted via provided BB_COMPARATOR. */ | |
881 | ||
882 | basic_block * | |
883 | get_loop_body_in_custom_order (const struct loop *loop, | |
884 | int (*bb_comparator) (const void *, const void *)) | |
885 | { | |
886 | basic_block *bbs = get_loop_body (loop); | |
887 | ||
888 | qsort (bbs, loop->num_nodes, sizeof (basic_block), bb_comparator); | |
889 | ||
890 | return bbs; | |
891 | } | |
892 | ||
893 | /* Get body of a LOOP in breadth first sort order. */ | |
894 | ||
895 | basic_block * | |
896 | get_loop_body_in_bfs_order (const struct loop *loop) | |
897 | { | |
898 | basic_block *blocks; | |
899 | basic_block bb; | |
900 | bitmap visited; | |
901 | unsigned int i = 0; | |
902 | unsigned int vc = 1; | |
903 | ||
904 | gcc_assert (loop->num_nodes); | |
905 | gcc_assert (loop->latch != EXIT_BLOCK_PTR); | |
906 | ||
907 | blocks = XNEWVEC (basic_block, loop->num_nodes); | |
908 | visited = BITMAP_ALLOC (NULL); | |
909 | ||
910 | bb = loop->header; | |
911 | while (i < loop->num_nodes) | |
912 | { | |
913 | edge e; | |
914 | edge_iterator ei; | |
915 | ||
916 | if (bitmap_set_bit (visited, bb->index)) | |
917 | /* This basic block is now visited */ | |
918 | blocks[i++] = bb; | |
919 | ||
920 | FOR_EACH_EDGE (e, ei, bb->succs) | |
921 | { | |
922 | if (flow_bb_inside_loop_p (loop, e->dest)) | |
923 | { | |
924 | if (bitmap_set_bit (visited, e->dest->index)) | |
925 | blocks[i++] = e->dest; | |
926 | } | |
927 | } | |
928 | ||
929 | gcc_assert (i >= vc); | |
930 | ||
931 | bb = blocks[vc++]; | |
932 | } | |
933 | ||
934 | BITMAP_FREE (visited); | |
935 | return blocks; | |
936 | } | |
937 | ||
938 | /* Hash function for struct loop_exit. */ | |
939 | ||
940 | static hashval_t | |
941 | loop_exit_hash (const void *ex) | |
942 | { | |
943 | const struct loop_exit *const exit = (const struct loop_exit *) ex; | |
944 | ||
945 | return htab_hash_pointer (exit->e); | |
946 | } | |
947 | ||
948 | /* Equality function for struct loop_exit. Compares with edge. */ | |
949 | ||
950 | static int | |
951 | loop_exit_eq (const void *ex, const void *e) | |
952 | { | |
953 | const struct loop_exit *const exit = (const struct loop_exit *) ex; | |
954 | ||
955 | return exit->e == e; | |
956 | } | |
957 | ||
958 | /* Frees the list of loop exit descriptions EX. */ | |
959 | ||
960 | static void | |
961 | loop_exit_free (void *ex) | |
962 | { | |
963 | struct loop_exit *exit = (struct loop_exit *) ex, *next; | |
964 | ||
965 | for (; exit; exit = next) | |
966 | { | |
967 | next = exit->next_e; | |
968 | ||
969 | exit->next->prev = exit->prev; | |
970 | exit->prev->next = exit->next; | |
971 | ||
972 | ggc_free (exit); | |
973 | } | |
974 | } | |
975 | ||
976 | /* Returns the list of records for E as an exit of a loop. */ | |
977 | ||
978 | static struct loop_exit * | |
979 | get_exit_descriptions (edge e) | |
980 | { | |
981 | return (struct loop_exit *) htab_find_with_hash (current_loops->exits, e, | |
982 | htab_hash_pointer (e)); | |
983 | } | |
984 | ||
985 | /* Updates the lists of loop exits in that E appears. | |
986 | If REMOVED is true, E is being removed, and we | |
987 | just remove it from the lists of exits. | |
988 | If NEW_EDGE is true and E is not a loop exit, we | |
989 | do not try to remove it from loop exit lists. */ | |
990 | ||
991 | void | |
992 | rescan_loop_exit (edge e, bool new_edge, bool removed) | |
993 | { | |
994 | void **slot; | |
995 | struct loop_exit *exits = NULL, *exit; | |
996 | struct loop *aloop, *cloop; | |
997 | ||
998 | if (!loops_state_satisfies_p (LOOPS_HAVE_RECORDED_EXITS)) | |
999 | return; | |
1000 | ||
1001 | if (!removed | |
1002 | && e->src->loop_father != NULL | |
1003 | && e->dest->loop_father != NULL | |
1004 | && !flow_bb_inside_loop_p (e->src->loop_father, e->dest)) | |
1005 | { | |
1006 | cloop = find_common_loop (e->src->loop_father, e->dest->loop_father); | |
1007 | for (aloop = e->src->loop_father; | |
1008 | aloop != cloop; | |
1009 | aloop = loop_outer (aloop)) | |
1010 | { | |
1011 | exit = ggc_alloc_loop_exit (); | |
1012 | exit->e = e; | |
1013 | ||
1014 | exit->next = aloop->exits->next; | |
1015 | exit->prev = aloop->exits; | |
1016 | exit->next->prev = exit; | |
1017 | exit->prev->next = exit; | |
1018 | ||
1019 | exit->next_e = exits; | |
1020 | exits = exit; | |
1021 | } | |
1022 | } | |
1023 | ||
1024 | if (!exits && new_edge) | |
1025 | return; | |
1026 | ||
1027 | slot = htab_find_slot_with_hash (current_loops->exits, e, | |
1028 | htab_hash_pointer (e), | |
1029 | exits ? INSERT : NO_INSERT); | |
1030 | if (!slot) | |
1031 | return; | |
1032 | ||
1033 | if (exits) | |
1034 | { | |
1035 | if (*slot) | |
1036 | loop_exit_free (*slot); | |
1037 | *slot = exits; | |
1038 | } | |
1039 | else | |
1040 | htab_clear_slot (current_loops->exits, slot); | |
1041 | } | |
1042 | ||
1043 | /* For each loop, record list of exit edges, and start maintaining these | |
1044 | lists. */ | |
1045 | ||
1046 | void | |
1047 | record_loop_exits (void) | |
1048 | { | |
1049 | basic_block bb; | |
1050 | edge_iterator ei; | |
1051 | edge e; | |
1052 | ||
1053 | if (!current_loops) | |
1054 | return; | |
1055 | ||
1056 | if (loops_state_satisfies_p (LOOPS_HAVE_RECORDED_EXITS)) | |
1057 | return; | |
1058 | loops_state_set (LOOPS_HAVE_RECORDED_EXITS); | |
1059 | ||
1060 | gcc_assert (current_loops->exits == NULL); | |
1061 | current_loops->exits = htab_create_ggc (2 * number_of_loops (), | |
1062 | loop_exit_hash, loop_exit_eq, | |
1063 | loop_exit_free); | |
1064 | ||
1065 | FOR_EACH_BB (bb) | |
1066 | { | |
1067 | FOR_EACH_EDGE (e, ei, bb->succs) | |
1068 | { | |
1069 | rescan_loop_exit (e, true, false); | |
1070 | } | |
1071 | } | |
1072 | } | |
1073 | ||
1074 | /* Dumps information about the exit in *SLOT to FILE. | |
1075 | Callback for htab_traverse. */ | |
1076 | ||
1077 | static int | |
1078 | dump_recorded_exit (void **slot, void *file) | |
1079 | { | |
1080 | struct loop_exit *exit = (struct loop_exit *) *slot; | |
1081 | unsigned n = 0; | |
1082 | edge e = exit->e; | |
1083 | ||
1084 | for (; exit != NULL; exit = exit->next_e) | |
1085 | n++; | |
1086 | ||
1087 | fprintf ((FILE*) file, "Edge %d->%d exits %u loops\n", | |
1088 | e->src->index, e->dest->index, n); | |
1089 | ||
1090 | return 1; | |
1091 | } | |
1092 | ||
1093 | /* Dumps the recorded exits of loops to FILE. */ | |
1094 | ||
1095 | extern void dump_recorded_exits (FILE *); | |
1096 | void | |
1097 | dump_recorded_exits (FILE *file) | |
1098 | { | |
1099 | if (!current_loops->exits) | |
1100 | return; | |
1101 | htab_traverse (current_loops->exits, dump_recorded_exit, file); | |
1102 | } | |
1103 | ||
1104 | /* Releases lists of loop exits. */ | |
1105 | ||
1106 | void | |
1107 | release_recorded_exits (void) | |
1108 | { | |
1109 | gcc_assert (loops_state_satisfies_p (LOOPS_HAVE_RECORDED_EXITS)); | |
1110 | htab_delete (current_loops->exits); | |
1111 | current_loops->exits = NULL; | |
1112 | loops_state_clear (LOOPS_HAVE_RECORDED_EXITS); | |
1113 | } | |
1114 | ||
1115 | /* Returns the list of the exit edges of a LOOP. */ | |
1116 | ||
1117 | vec<edge> | |
1118 | get_loop_exit_edges (const struct loop *loop) | |
1119 | { | |
1120 | vec<edge> edges = vNULL; | |
1121 | edge e; | |
1122 | unsigned i; | |
1123 | basic_block *body; | |
1124 | edge_iterator ei; | |
1125 | struct loop_exit *exit; | |
1126 | ||
1127 | gcc_assert (loop->latch != EXIT_BLOCK_PTR); | |
1128 | ||
1129 | /* If we maintain the lists of exits, use them. Otherwise we must | |
1130 | scan the body of the loop. */ | |
1131 | if (loops_state_satisfies_p (LOOPS_HAVE_RECORDED_EXITS)) | |
1132 | { | |
1133 | for (exit = loop->exits->next; exit->e; exit = exit->next) | |
1134 | edges.safe_push (exit->e); | |
1135 | } | |
1136 | else | |
1137 | { | |
1138 | body = get_loop_body (loop); | |
1139 | for (i = 0; i < loop->num_nodes; i++) | |
1140 | FOR_EACH_EDGE (e, ei, body[i]->succs) | |
1141 | { | |
1142 | if (!flow_bb_inside_loop_p (loop, e->dest)) | |
1143 | edges.safe_push (e); | |
1144 | } | |
1145 | free (body); | |
1146 | } | |
1147 | ||
1148 | return edges; | |
1149 | } | |
1150 | ||
1151 | /* Counts the number of conditional branches inside LOOP. */ | |
1152 | ||
1153 | unsigned | |
1154 | num_loop_branches (const struct loop *loop) | |
1155 | { | |
1156 | unsigned i, n; | |
1157 | basic_block * body; | |
1158 | ||
1159 | gcc_assert (loop->latch != EXIT_BLOCK_PTR); | |
1160 | ||
1161 | body = get_loop_body (loop); | |
1162 | n = 0; | |
1163 | for (i = 0; i < loop->num_nodes; i++) | |
1164 | if (EDGE_COUNT (body[i]->succs) >= 2) | |
1165 | n++; | |
1166 | free (body); | |
1167 | ||
1168 | return n; | |
1169 | } | |
1170 | ||
1171 | /* Adds basic block BB to LOOP. */ | |
1172 | void | |
1173 | add_bb_to_loop (basic_block bb, struct loop *loop) | |
1174 | { | |
1175 | unsigned i; | |
1176 | loop_p ploop; | |
1177 | edge_iterator ei; | |
1178 | edge e; | |
1179 | ||
1180 | gcc_assert (bb->loop_father == NULL); | |
1181 | bb->loop_father = loop; | |
1182 | loop->num_nodes++; | |
1183 | FOR_EACH_VEC_SAFE_ELT (loop->superloops, i, ploop) | |
1184 | ploop->num_nodes++; | |
1185 | ||
1186 | FOR_EACH_EDGE (e, ei, bb->succs) | |
1187 | { | |
1188 | rescan_loop_exit (e, true, false); | |
1189 | } | |
1190 | FOR_EACH_EDGE (e, ei, bb->preds) | |
1191 | { | |
1192 | rescan_loop_exit (e, true, false); | |
1193 | } | |
1194 | } | |
1195 | ||
1196 | /* Remove basic block BB from loops. */ | |
1197 | void | |
1198 | remove_bb_from_loops (basic_block bb) | |
1199 | { | |
1200 | unsigned i; | |
1201 | struct loop *loop = bb->loop_father; | |
1202 | loop_p ploop; | |
1203 | edge_iterator ei; | |
1204 | edge e; | |
1205 | ||
1206 | gcc_assert (loop != NULL); | |
1207 | loop->num_nodes--; | |
1208 | FOR_EACH_VEC_SAFE_ELT (loop->superloops, i, ploop) | |
1209 | ploop->num_nodes--; | |
1210 | bb->loop_father = NULL; | |
1211 | ||
1212 | FOR_EACH_EDGE (e, ei, bb->succs) | |
1213 | { | |
1214 | rescan_loop_exit (e, false, true); | |
1215 | } | |
1216 | FOR_EACH_EDGE (e, ei, bb->preds) | |
1217 | { | |
1218 | rescan_loop_exit (e, false, true); | |
1219 | } | |
1220 | } | |
1221 | ||
1222 | /* Finds nearest common ancestor in loop tree for given loops. */ | |
1223 | struct loop * | |
1224 | find_common_loop (struct loop *loop_s, struct loop *loop_d) | |
1225 | { | |
1226 | unsigned sdepth, ddepth; | |
1227 | ||
1228 | if (!loop_s) return loop_d; | |
1229 | if (!loop_d) return loop_s; | |
1230 | ||
1231 | sdepth = loop_depth (loop_s); | |
1232 | ddepth = loop_depth (loop_d); | |
1233 | ||
1234 | if (sdepth < ddepth) | |
1235 | loop_d = (*loop_d->superloops)[sdepth]; | |
1236 | else if (sdepth > ddepth) | |
1237 | loop_s = (*loop_s->superloops)[ddepth]; | |
1238 | ||
1239 | while (loop_s != loop_d) | |
1240 | { | |
1241 | loop_s = loop_outer (loop_s); | |
1242 | loop_d = loop_outer (loop_d); | |
1243 | } | |
1244 | return loop_s; | |
1245 | } | |
1246 | ||
1247 | /* Removes LOOP from structures and frees its data. */ | |
1248 | ||
1249 | void | |
1250 | delete_loop (struct loop *loop) | |
1251 | { | |
1252 | /* Remove the loop from structure. */ | |
1253 | flow_loop_tree_node_remove (loop); | |
1254 | ||
1255 | /* Remove loop from loops array. */ | |
1256 | (*current_loops->larray)[loop->num] = NULL; | |
1257 | ||
1258 | /* Free loop data. */ | |
1259 | flow_loop_free (loop); | |
1260 | } | |
1261 | ||
1262 | /* Cancels the LOOP; it must be innermost one. */ | |
1263 | ||
1264 | static void | |
1265 | cancel_loop (struct loop *loop) | |
1266 | { | |
1267 | basic_block *bbs; | |
1268 | unsigned i; | |
1269 | struct loop *outer = loop_outer (loop); | |
1270 | ||
1271 | gcc_assert (!loop->inner); | |
1272 | ||
1273 | /* Move blocks up one level (they should be removed as soon as possible). */ | |
1274 | bbs = get_loop_body (loop); | |
1275 | for (i = 0; i < loop->num_nodes; i++) | |
1276 | bbs[i]->loop_father = outer; | |
1277 | ||
1278 | free (bbs); | |
1279 | delete_loop (loop); | |
1280 | } | |
1281 | ||
1282 | /* Cancels LOOP and all its subloops. */ | |
1283 | void | |
1284 | cancel_loop_tree (struct loop *loop) | |
1285 | { | |
1286 | while (loop->inner) | |
1287 | cancel_loop_tree (loop->inner); | |
1288 | cancel_loop (loop); | |
1289 | } | |
1290 | ||
1291 | /* Checks that information about loops is correct | |
1292 | -- sizes of loops are all right | |
1293 | -- results of get_loop_body really belong to the loop | |
1294 | -- loop header have just single entry edge and single latch edge | |
1295 | -- loop latches have only single successor that is header of their loop | |
1296 | -- irreducible loops are correctly marked | |
1297 | -- the cached loop depth and loop father of each bb is correct | |
1298 | */ | |
1299 | DEBUG_FUNCTION void | |
1300 | verify_loop_structure (void) | |
1301 | { | |
1302 | unsigned *sizes, i, j; | |
1303 | sbitmap irreds; | |
1304 | basic_block *bbs, bb; | |
1305 | struct loop *loop; | |
1306 | int err = 0; | |
1307 | edge e; | |
1308 | unsigned num = number_of_loops (); | |
1309 | loop_iterator li; | |
1310 | struct loop_exit *exit, *mexit; | |
1311 | bool dom_available = dom_info_available_p (CDI_DOMINATORS); | |
1312 | sbitmap visited = sbitmap_alloc (last_basic_block); | |
1313 | ||
1314 | /* We need up-to-date dominators, compute or verify them. */ | |
1315 | if (!dom_available) | |
1316 | calculate_dominance_info (CDI_DOMINATORS); | |
1317 | else | |
1318 | verify_dominators (CDI_DOMINATORS); | |
1319 | ||
1320 | /* Check sizes. */ | |
1321 | sizes = XCNEWVEC (unsigned, num); | |
1322 | sizes[0] = 2; | |
1323 | ||
1324 | FOR_EACH_BB (bb) | |
1325 | for (loop = bb->loop_father; loop; loop = loop_outer (loop)) | |
1326 | sizes[loop->num]++; | |
1327 | ||
1328 | FOR_EACH_LOOP (li, loop, LI_INCLUDE_ROOT) | |
1329 | { | |
1330 | i = loop->num; | |
1331 | ||
1332 | if (loop->num_nodes != sizes[i]) | |
1333 | { | |
1334 | error ("size of loop %d should be %d, not %d", | |
1335 | i, sizes[i], loop->num_nodes); | |
1336 | err = 1; | |
1337 | } | |
1338 | } | |
1339 | ||
1340 | /* Check get_loop_body. */ | |
1341 | FOR_EACH_LOOP (li, loop, 0) | |
1342 | { | |
1343 | bbs = get_loop_body (loop); | |
1344 | ||
1345 | for (j = 0; j < loop->num_nodes; j++) | |
1346 | if (!flow_bb_inside_loop_p (loop, bbs[j])) | |
1347 | { | |
1348 | error ("bb %d do not belong to loop %d", | |
1349 | bbs[j]->index, loop->num); | |
1350 | err = 1; | |
1351 | } | |
1352 | free (bbs); | |
1353 | } | |
1354 | bitmap_clear (visited); | |
1355 | FOR_EACH_LOOP (li, loop, LI_FROM_INNERMOST) | |
1356 | { | |
1357 | bbs = get_loop_body (loop); | |
1358 | ||
1359 | for (j = 0; j < loop->num_nodes; j++) | |
1360 | { | |
1361 | bb = bbs[j]; | |
1362 | ||
1363 | /* Ignore this block if it is in an inner loop. */ | |
1364 | if (bitmap_bit_p (visited, bb->index)) | |
1365 | continue; | |
1366 | bitmap_set_bit (visited, bb->index); | |
1367 | ||
1368 | if (bb->loop_father != loop) | |
1369 | { | |
1370 | error ("bb %d has father loop %d, should be loop %d", | |
1371 | bb->index, bb->loop_father->num, loop->num); | |
1372 | err = 1; | |
1373 | } | |
1374 | } | |
1375 | free (bbs); | |
1376 | } | |
1377 | ||
1378 | /* Check headers and latches. */ | |
1379 | FOR_EACH_LOOP (li, loop, 0) | |
1380 | { | |
1381 | i = loop->num; | |
1382 | ||
1383 | if (loops_state_satisfies_p (LOOPS_HAVE_PREHEADERS) | |
1384 | && EDGE_COUNT (loop->header->preds) != 2) | |
1385 | { | |
1386 | error ("loop %d%'s header does not have exactly 2 entries", i); | |
1387 | err = 1; | |
1388 | } | |
1389 | if (loops_state_satisfies_p (LOOPS_HAVE_SIMPLE_LATCHES)) | |
1390 | { | |
1391 | if (!single_succ_p (loop->latch)) | |
1392 | { | |
1393 | error ("loop %d%'s latch does not have exactly 1 successor", i); | |
1394 | err = 1; | |
1395 | } | |
1396 | if (single_succ (loop->latch) != loop->header) | |
1397 | { | |
1398 | error ("loop %d%'s latch does not have header as successor", i); | |
1399 | err = 1; | |
1400 | } | |
1401 | if (loop->latch->loop_father != loop) | |
1402 | { | |
1403 | error ("loop %d%'s latch does not belong directly to it", i); | |
1404 | err = 1; | |
1405 | } | |
1406 | } | |
1407 | if (loop->header->loop_father != loop) | |
1408 | { | |
1409 | error ("loop %d%'s header does not belong directly to it", i); | |
1410 | err = 1; | |
1411 | } | |
1412 | if (loops_state_satisfies_p (LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS) | |
1413 | && (loop_latch_edge (loop)->flags & EDGE_IRREDUCIBLE_LOOP)) | |
1414 | { | |
1415 | error ("loop %d%'s latch is marked as part of irreducible region", i); | |
1416 | err = 1; | |
1417 | } | |
1418 | } | |
1419 | ||
1420 | /* Check irreducible loops. */ | |
1421 | if (loops_state_satisfies_p (LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS)) | |
1422 | { | |
1423 | /* Record old info. */ | |
1424 | irreds = sbitmap_alloc (last_basic_block); | |
1425 | FOR_EACH_BB (bb) | |
1426 | { | |
1427 | edge_iterator ei; | |
1428 | if (bb->flags & BB_IRREDUCIBLE_LOOP) | |
1429 | bitmap_set_bit (irreds, bb->index); | |
1430 | else | |
1431 | bitmap_clear_bit (irreds, bb->index); | |
1432 | FOR_EACH_EDGE (e, ei, bb->succs) | |
1433 | if (e->flags & EDGE_IRREDUCIBLE_LOOP) | |
1434 | e->flags |= EDGE_ALL_FLAGS + 1; | |
1435 | } | |
1436 | ||
1437 | /* Recount it. */ | |
1438 | mark_irreducible_loops (); | |
1439 | ||
1440 | /* Compare. */ | |
1441 | FOR_EACH_BB (bb) | |
1442 | { | |
1443 | edge_iterator ei; | |
1444 | ||
1445 | if ((bb->flags & BB_IRREDUCIBLE_LOOP) | |
1446 | && !bitmap_bit_p (irreds, bb->index)) | |
1447 | { | |
1448 | error ("basic block %d should be marked irreducible", bb->index); | |
1449 | err = 1; | |
1450 | } | |
1451 | else if (!(bb->flags & BB_IRREDUCIBLE_LOOP) | |
1452 | && bitmap_bit_p (irreds, bb->index)) | |
1453 | { | |
1454 | error ("basic block %d should not be marked irreducible", bb->index); | |
1455 | err = 1; | |
1456 | } | |
1457 | FOR_EACH_EDGE (e, ei, bb->succs) | |
1458 | { | |
1459 | if ((e->flags & EDGE_IRREDUCIBLE_LOOP) | |
1460 | && !(e->flags & (EDGE_ALL_FLAGS + 1))) | |
1461 | { | |
1462 | error ("edge from %d to %d should be marked irreducible", | |
1463 | e->src->index, e->dest->index); | |
1464 | err = 1; | |
1465 | } | |
1466 | else if (!(e->flags & EDGE_IRREDUCIBLE_LOOP) | |
1467 | && (e->flags & (EDGE_ALL_FLAGS + 1))) | |
1468 | { | |
1469 | error ("edge from %d to %d should not be marked irreducible", | |
1470 | e->src->index, e->dest->index); | |
1471 | err = 1; | |
1472 | } | |
1473 | e->flags &= ~(EDGE_ALL_FLAGS + 1); | |
1474 | } | |
1475 | } | |
1476 | free (irreds); | |
1477 | } | |
1478 | ||
1479 | /* Check the recorded loop exits. */ | |
1480 | FOR_EACH_LOOP (li, loop, 0) | |
1481 | { | |
1482 | if (!loop->exits || loop->exits->e != NULL) | |
1483 | { | |
1484 | error ("corrupted head of the exits list of loop %d", | |
1485 | loop->num); | |
1486 | err = 1; | |
1487 | } | |
1488 | else | |
1489 | { | |
1490 | /* Check that the list forms a cycle, and all elements except | |
1491 | for the head are nonnull. */ | |
1492 | for (mexit = loop->exits, exit = mexit->next, i = 0; | |
1493 | exit->e && exit != mexit; | |
1494 | exit = exit->next) | |
1495 | { | |
1496 | if (i++ & 1) | |
1497 | mexit = mexit->next; | |
1498 | } | |
1499 | ||
1500 | if (exit != loop->exits) | |
1501 | { | |
1502 | error ("corrupted exits list of loop %d", loop->num); | |
1503 | err = 1; | |
1504 | } | |
1505 | } | |
1506 | ||
1507 | if (!loops_state_satisfies_p (LOOPS_HAVE_RECORDED_EXITS)) | |
1508 | { | |
1509 | if (loop->exits->next != loop->exits) | |
1510 | { | |
1511 | error ("nonempty exits list of loop %d, but exits are not recorded", | |
1512 | loop->num); | |
1513 | err = 1; | |
1514 | } | |
1515 | } | |
1516 | } | |
1517 | ||
1518 | if (loops_state_satisfies_p (LOOPS_HAVE_RECORDED_EXITS)) | |
1519 | { | |
1520 | unsigned n_exits = 0, eloops; | |
1521 | ||
1522 | memset (sizes, 0, sizeof (unsigned) * num); | |
1523 | FOR_EACH_BB (bb) | |
1524 | { | |
1525 | edge_iterator ei; | |
1526 | if (bb->loop_father == current_loops->tree_root) | |
1527 | continue; | |
1528 | FOR_EACH_EDGE (e, ei, bb->succs) | |
1529 | { | |
1530 | if (flow_bb_inside_loop_p (bb->loop_father, e->dest)) | |
1531 | continue; | |
1532 | ||
1533 | n_exits++; | |
1534 | exit = get_exit_descriptions (e); | |
1535 | if (!exit) | |
1536 | { | |
1537 | error ("exit %d->%d not recorded", | |
1538 | e->src->index, e->dest->index); | |
1539 | err = 1; | |
1540 | } | |
1541 | eloops = 0; | |
1542 | for (; exit; exit = exit->next_e) | |
1543 | eloops++; | |
1544 | ||
1545 | for (loop = bb->loop_father; | |
1546 | loop != e->dest->loop_father; | |
1547 | loop = loop_outer (loop)) | |
1548 | { | |
1549 | eloops--; | |
1550 | sizes[loop->num]++; | |
1551 | } | |
1552 | ||
1553 | if (eloops != 0) | |
1554 | { | |
1555 | error ("wrong list of exited loops for edge %d->%d", | |
1556 | e->src->index, e->dest->index); | |
1557 | err = 1; | |
1558 | } | |
1559 | } | |
1560 | } | |
1561 | ||
1562 | if (n_exits != htab_elements (current_loops->exits)) | |
1563 | { | |
1564 | error ("too many loop exits recorded"); | |
1565 | err = 1; | |
1566 | } | |
1567 | ||
1568 | FOR_EACH_LOOP (li, loop, 0) | |
1569 | { | |
1570 | eloops = 0; | |
1571 | for (exit = loop->exits->next; exit->e; exit = exit->next) | |
1572 | eloops++; | |
1573 | if (eloops != sizes[loop->num]) | |
1574 | { | |
1575 | error ("%d exits recorded for loop %d (having %d exits)", | |
1576 | eloops, loop->num, sizes[loop->num]); | |
1577 | err = 1; | |
1578 | } | |
1579 | } | |
1580 | } | |
1581 | ||
1582 | gcc_assert (!err); | |
1583 | ||
1584 | sbitmap_free (visited); | |
1585 | free (sizes); | |
1586 | if (!dom_available) | |
1587 | free_dominance_info (CDI_DOMINATORS); | |
1588 | } | |
1589 | ||
1590 | /* Returns latch edge of LOOP. */ | |
1591 | edge | |
1592 | loop_latch_edge (const struct loop *loop) | |
1593 | { | |
1594 | return find_edge (loop->latch, loop->header); | |
1595 | } | |
1596 | ||
1597 | /* Returns preheader edge of LOOP. */ | |
1598 | edge | |
1599 | loop_preheader_edge (const struct loop *loop) | |
1600 | { | |
1601 | edge e; | |
1602 | edge_iterator ei; | |
1603 | ||
1604 | gcc_assert (loops_state_satisfies_p (LOOPS_HAVE_PREHEADERS)); | |
1605 | ||
1606 | FOR_EACH_EDGE (e, ei, loop->header->preds) | |
1607 | if (e->src != loop->latch) | |
1608 | break; | |
1609 | ||
1610 | return e; | |
1611 | } | |
1612 | ||
1613 | /* Returns true if E is an exit of LOOP. */ | |
1614 | ||
1615 | bool | |
1616 | loop_exit_edge_p (const struct loop *loop, const_edge e) | |
1617 | { | |
1618 | return (flow_bb_inside_loop_p (loop, e->src) | |
1619 | && !flow_bb_inside_loop_p (loop, e->dest)); | |
1620 | } | |
1621 | ||
1622 | /* Returns the single exit edge of LOOP, or NULL if LOOP has either no exit | |
1623 | or more than one exit. If loops do not have the exits recorded, NULL | |
1624 | is returned always. */ | |
1625 | ||
1626 | edge | |
1627 | single_exit (const struct loop *loop) | |
1628 | { | |
1629 | struct loop_exit *exit = loop->exits->next; | |
1630 | ||
1631 | if (!loops_state_satisfies_p (LOOPS_HAVE_RECORDED_EXITS)) | |
1632 | return NULL; | |
1633 | ||
1634 | if (exit->e && exit->next == loop->exits) | |
1635 | return exit->e; | |
1636 | else | |
1637 | return NULL; | |
1638 | } | |
1639 | ||
1640 | /* Returns true when BB has an incoming edge exiting LOOP. */ | |
1641 | ||
1642 | bool | |
1643 | loop_exits_to_bb_p (struct loop *loop, basic_block bb) | |
1644 | { | |
1645 | edge e; | |
1646 | edge_iterator ei; | |
1647 | ||
1648 | FOR_EACH_EDGE (e, ei, bb->preds) | |
1649 | if (loop_exit_edge_p (loop, e)) | |
1650 | return true; | |
1651 | ||
1652 | return false; | |
1653 | } | |
1654 | ||
1655 | /* Returns true when BB has an outgoing edge exiting LOOP. */ | |
1656 | ||
1657 | bool | |
1658 | loop_exits_from_bb_p (struct loop *loop, basic_block bb) | |
1659 | { | |
1660 | edge e; | |
1661 | edge_iterator ei; | |
1662 | ||
1663 | FOR_EACH_EDGE (e, ei, bb->succs) | |
1664 | if (loop_exit_edge_p (loop, e)) | |
1665 | return true; | |
1666 | ||
1667 | return false; | |
1668 | } |