don't compare ARG_FRAME_POINTER_REGNUM and FRAME_POINTER_REGNUM with the preprocessor
[official-gcc.git] / gcc / cfgloopmanip.c
blob45cc85da8638e0b34dfc00b6b1e7088e3069f50e
1 /* Loop manipulation code for GNU compiler.
2 Copyright (C) 2002-2015 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it under
7 the terms of the GNU General Public License as published by the Free
8 Software Foundation; either version 3, or (at your option) any later
9 version.
11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 for more details.
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING3. If not see
18 <http://www.gnu.org/licenses/>. */
20 #include "config.h"
21 #include "system.h"
22 #include "coretypes.h"
23 #include "tm.h"
24 #include "rtl.h"
25 #include "predict.h"
26 #include "vec.h"
27 #include "hashtab.h"
28 #include "hash-set.h"
29 #include "symtab.h"
30 #include "inchash.h"
31 #include "machmode.h"
32 #include "hard-reg-set.h"
33 #include "input.h"
34 #include "function.h"
35 #include "dominance.h"
36 #include "cfg.h"
37 #include "cfganal.h"
38 #include "basic-block.h"
39 #include "cfgloop.h"
40 #include "tree.h"
41 #include "fold-const.h"
42 #include "tree-ssa-alias.h"
43 #include "internal-fn.h"
44 #include "gimple-expr.h"
45 #include "is-a.h"
46 #include "gimple.h"
47 #include "gimple-iterator.h"
48 #include "gimplify-me.h"
49 #include "tree-ssa-loop-manip.h"
50 #include "dumpfile.h"
52 static void copy_loops_to (struct loop **, int,
53 struct loop *);
54 static void loop_redirect_edge (edge, basic_block);
55 static void remove_bbs (basic_block *, int);
56 static bool rpe_enum_p (const_basic_block, const void *);
57 static int find_path (edge, basic_block **);
58 static void fix_loop_placements (struct loop *, bool *);
59 static bool fix_bb_placement (basic_block);
60 static void fix_bb_placements (basic_block, bool *, bitmap);
62 /* Checks whether basic block BB is dominated by DATA. */
63 static bool
64 rpe_enum_p (const_basic_block bb, const void *data)
66 return dominated_by_p (CDI_DOMINATORS, bb, (const_basic_block) data);
69 /* Remove basic blocks BBS. NBBS is the number of the basic blocks. */
71 static void
72 remove_bbs (basic_block *bbs, int nbbs)
74 int i;
76 for (i = 0; i < nbbs; i++)
77 delete_basic_block (bbs[i]);
80 /* Find path -- i.e. the basic blocks dominated by edge E and put them
81 into array BBS, that will be allocated large enough to contain them.
82 E->dest must have exactly one predecessor for this to work (it is
83 easy to achieve and we do not put it here because we do not want to
84 alter anything by this function). The number of basic blocks in the
85 path is returned. */
86 static int
87 find_path (edge e, basic_block **bbs)
89 gcc_assert (EDGE_COUNT (e->dest->preds) <= 1);
91 /* Find bbs in the path. */
92 *bbs = XNEWVEC (basic_block, n_basic_blocks_for_fn (cfun));
93 return dfs_enumerate_from (e->dest, 0, rpe_enum_p, *bbs,
94 n_basic_blocks_for_fn (cfun), e->dest);
97 /* Fix placement of basic block BB inside loop hierarchy --
98 Let L be a loop to that BB belongs. Then every successor of BB must either
99 1) belong to some superloop of loop L, or
100 2) be a header of loop K such that K->outer is superloop of L
101 Returns true if we had to move BB into other loop to enforce this condition,
102 false if the placement of BB was already correct (provided that placements
103 of its successors are correct). */
104 static bool
105 fix_bb_placement (basic_block bb)
107 edge e;
108 edge_iterator ei;
109 struct loop *loop = current_loops->tree_root, *act;
111 FOR_EACH_EDGE (e, ei, bb->succs)
113 if (e->dest == EXIT_BLOCK_PTR_FOR_FN (cfun))
114 continue;
116 act = e->dest->loop_father;
117 if (act->header == e->dest)
118 act = loop_outer (act);
120 if (flow_loop_nested_p (loop, act))
121 loop = act;
124 if (loop == bb->loop_father)
125 return false;
127 remove_bb_from_loops (bb);
128 add_bb_to_loop (bb, loop);
130 return true;
133 /* Fix placement of LOOP inside loop tree, i.e. find the innermost superloop
134 of LOOP to that leads at least one exit edge of LOOP, and set it
135 as the immediate superloop of LOOP. Return true if the immediate superloop
136 of LOOP changed.
138 IRRED_INVALIDATED is set to true if a change in the loop structures might
139 invalidate the information about irreducible regions. */
141 static bool
142 fix_loop_placement (struct loop *loop, bool *irred_invalidated)
144 unsigned i;
145 edge e;
146 vec<edge> exits = get_loop_exit_edges (loop);
147 struct loop *father = current_loops->tree_root, *act;
148 bool ret = false;
150 FOR_EACH_VEC_ELT (exits, i, e)
152 act = find_common_loop (loop, e->dest->loop_father);
153 if (flow_loop_nested_p (father, act))
154 father = act;
157 if (father != loop_outer (loop))
159 for (act = loop_outer (loop); act != father; act = loop_outer (act))
160 act->num_nodes -= loop->num_nodes;
161 flow_loop_tree_node_remove (loop);
162 flow_loop_tree_node_add (father, loop);
164 /* The exit edges of LOOP no longer exits its original immediate
165 superloops; remove them from the appropriate exit lists. */
166 FOR_EACH_VEC_ELT (exits, i, e)
168 /* We may need to recompute irreducible loops. */
169 if (e->flags & EDGE_IRREDUCIBLE_LOOP)
170 *irred_invalidated = true;
171 rescan_loop_exit (e, false, false);
174 ret = true;
177 exits.release ();
178 return ret;
181 /* Fix placements of basic blocks inside loop hierarchy stored in loops; i.e.
182 enforce condition condition stated in description of fix_bb_placement. We
183 start from basic block FROM that had some of its successors removed, so that
184 his placement no longer has to be correct, and iteratively fix placement of
185 its predecessors that may change if placement of FROM changed. Also fix
186 placement of subloops of FROM->loop_father, that might also be altered due
187 to this change; the condition for them is similar, except that instead of
188 successors we consider edges coming out of the loops.
190 If the changes may invalidate the information about irreducible regions,
191 IRRED_INVALIDATED is set to true.
193 If LOOP_CLOSED_SSA_INVLIDATED is non-zero then all basic blocks with
194 changed loop_father are collected there. */
196 static void
197 fix_bb_placements (basic_block from,
198 bool *irred_invalidated,
199 bitmap loop_closed_ssa_invalidated)
201 sbitmap in_queue;
202 basic_block *queue, *qtop, *qbeg, *qend;
203 struct loop *base_loop, *target_loop;
204 edge e;
206 /* We pass through blocks back-reachable from FROM, testing whether some
207 of their successors moved to outer loop. It may be necessary to
208 iterate several times, but it is finite, as we stop unless we move
209 the basic block up the loop structure. The whole story is a bit
210 more complicated due to presence of subloops, those are moved using
211 fix_loop_placement. */
213 base_loop = from->loop_father;
214 /* If we are already in the outermost loop, the basic blocks cannot be moved
215 outside of it. If FROM is the header of the base loop, it cannot be moved
216 outside of it, either. In both cases, we can end now. */
217 if (base_loop == current_loops->tree_root
218 || from == base_loop->header)
219 return;
221 in_queue = sbitmap_alloc (last_basic_block_for_fn (cfun));
222 bitmap_clear (in_queue);
223 bitmap_set_bit (in_queue, from->index);
224 /* Prevent us from going out of the base_loop. */
225 bitmap_set_bit (in_queue, base_loop->header->index);
227 queue = XNEWVEC (basic_block, base_loop->num_nodes + 1);
228 qtop = queue + base_loop->num_nodes + 1;
229 qbeg = queue;
230 qend = queue + 1;
231 *qbeg = from;
233 while (qbeg != qend)
235 edge_iterator ei;
236 from = *qbeg;
237 qbeg++;
238 if (qbeg == qtop)
239 qbeg = queue;
240 bitmap_clear_bit (in_queue, from->index);
242 if (from->loop_father->header == from)
244 /* Subloop header, maybe move the loop upward. */
245 if (!fix_loop_placement (from->loop_father, irred_invalidated))
246 continue;
247 target_loop = loop_outer (from->loop_father);
248 if (loop_closed_ssa_invalidated)
250 basic_block *bbs = get_loop_body (from->loop_father);
251 for (unsigned i = 0; i < from->loop_father->num_nodes; ++i)
252 bitmap_set_bit (loop_closed_ssa_invalidated, bbs[i]->index);
253 free (bbs);
256 else
258 /* Ordinary basic block. */
259 if (!fix_bb_placement (from))
260 continue;
261 target_loop = from->loop_father;
262 if (loop_closed_ssa_invalidated)
263 bitmap_set_bit (loop_closed_ssa_invalidated, from->index);
266 FOR_EACH_EDGE (e, ei, from->succs)
268 if (e->flags & EDGE_IRREDUCIBLE_LOOP)
269 *irred_invalidated = true;
272 /* Something has changed, insert predecessors into queue. */
273 FOR_EACH_EDGE (e, ei, from->preds)
275 basic_block pred = e->src;
276 struct loop *nca;
278 if (e->flags & EDGE_IRREDUCIBLE_LOOP)
279 *irred_invalidated = true;
281 if (bitmap_bit_p (in_queue, pred->index))
282 continue;
284 /* If it is subloop, then it either was not moved, or
285 the path up the loop tree from base_loop do not contain
286 it. */
287 nca = find_common_loop (pred->loop_father, base_loop);
288 if (pred->loop_father != base_loop
289 && (nca == base_loop
290 || nca != pred->loop_father))
291 pred = pred->loop_father->header;
292 else if (!flow_loop_nested_p (target_loop, pred->loop_father))
294 /* If PRED is already higher in the loop hierarchy than the
295 TARGET_LOOP to that we moved FROM, the change of the position
296 of FROM does not affect the position of PRED, so there is no
297 point in processing it. */
298 continue;
301 if (bitmap_bit_p (in_queue, pred->index))
302 continue;
304 /* Schedule the basic block. */
305 *qend = pred;
306 qend++;
307 if (qend == qtop)
308 qend = queue;
309 bitmap_set_bit (in_queue, pred->index);
312 free (in_queue);
313 free (queue);
316 /* Removes path beginning at edge E, i.e. remove basic blocks dominated by E
317 and update loop structures and dominators. Return true if we were able
318 to remove the path, false otherwise (and nothing is affected then). */
319 bool
320 remove_path (edge e)
322 edge ae;
323 basic_block *rem_bbs, *bord_bbs, from, bb;
324 vec<basic_block> dom_bbs;
325 int i, nrem, n_bord_bbs;
326 sbitmap seen;
327 bool irred_invalidated = false;
328 edge_iterator ei;
329 struct loop *l, *f;
331 if (!can_remove_branch_p (e))
332 return false;
334 /* Keep track of whether we need to update information about irreducible
335 regions. This is the case if the removed area is a part of the
336 irreducible region, or if the set of basic blocks that belong to a loop
337 that is inside an irreducible region is changed, or if such a loop is
338 removed. */
339 if (e->flags & EDGE_IRREDUCIBLE_LOOP)
340 irred_invalidated = true;
342 /* We need to check whether basic blocks are dominated by the edge
343 e, but we only have basic block dominators. This is easy to
344 fix -- when e->dest has exactly one predecessor, this corresponds
345 to blocks dominated by e->dest, if not, split the edge. */
346 if (!single_pred_p (e->dest))
347 e = single_pred_edge (split_edge (e));
349 /* It may happen that by removing path we remove one or more loops
350 we belong to. In this case first unloop the loops, then proceed
351 normally. We may assume that e->dest is not a header of any loop,
352 as it now has exactly one predecessor. */
353 for (l = e->src->loop_father; loop_outer (l); l = f)
355 f = loop_outer (l);
356 if (dominated_by_p (CDI_DOMINATORS, l->latch, e->dest))
357 unloop (l, &irred_invalidated, NULL);
360 /* Identify the path. */
361 nrem = find_path (e, &rem_bbs);
363 n_bord_bbs = 0;
364 bord_bbs = XNEWVEC (basic_block, n_basic_blocks_for_fn (cfun));
365 seen = sbitmap_alloc (last_basic_block_for_fn (cfun));
366 bitmap_clear (seen);
368 /* Find "border" hexes -- i.e. those with predecessor in removed path. */
369 for (i = 0; i < nrem; i++)
370 bitmap_set_bit (seen, rem_bbs[i]->index);
371 if (!irred_invalidated)
372 FOR_EACH_EDGE (ae, ei, e->src->succs)
373 if (ae != e && ae->dest != EXIT_BLOCK_PTR_FOR_FN (cfun)
374 && !bitmap_bit_p (seen, ae->dest->index)
375 && ae->flags & EDGE_IRREDUCIBLE_LOOP)
377 irred_invalidated = true;
378 break;
381 for (i = 0; i < nrem; i++)
383 bb = rem_bbs[i];
384 FOR_EACH_EDGE (ae, ei, rem_bbs[i]->succs)
385 if (ae->dest != EXIT_BLOCK_PTR_FOR_FN (cfun)
386 && !bitmap_bit_p (seen, ae->dest->index))
388 bitmap_set_bit (seen, ae->dest->index);
389 bord_bbs[n_bord_bbs++] = ae->dest;
391 if (ae->flags & EDGE_IRREDUCIBLE_LOOP)
392 irred_invalidated = true;
396 /* Remove the path. */
397 from = e->src;
398 remove_branch (e);
399 dom_bbs.create (0);
401 /* Cancel loops contained in the path. */
402 for (i = 0; i < nrem; i++)
403 if (rem_bbs[i]->loop_father->header == rem_bbs[i])
404 cancel_loop_tree (rem_bbs[i]->loop_father);
406 remove_bbs (rem_bbs, nrem);
407 free (rem_bbs);
409 /* Find blocks whose dominators may be affected. */
410 bitmap_clear (seen);
411 for (i = 0; i < n_bord_bbs; i++)
413 basic_block ldom;
415 bb = get_immediate_dominator (CDI_DOMINATORS, bord_bbs[i]);
416 if (bitmap_bit_p (seen, bb->index))
417 continue;
418 bitmap_set_bit (seen, bb->index);
420 for (ldom = first_dom_son (CDI_DOMINATORS, bb);
421 ldom;
422 ldom = next_dom_son (CDI_DOMINATORS, ldom))
423 if (!dominated_by_p (CDI_DOMINATORS, from, ldom))
424 dom_bbs.safe_push (ldom);
427 free (seen);
429 /* Recount dominators. */
430 iterate_fix_dominators (CDI_DOMINATORS, dom_bbs, true);
431 dom_bbs.release ();
432 free (bord_bbs);
434 /* Fix placements of basic blocks inside loops and the placement of
435 loops in the loop tree. */
436 fix_bb_placements (from, &irred_invalidated, NULL);
437 fix_loop_placements (from->loop_father, &irred_invalidated);
439 if (irred_invalidated
440 && loops_state_satisfies_p (LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS))
441 mark_irreducible_loops ();
443 return true;
446 /* Creates place for a new LOOP in loops structure of FN. */
448 void
449 place_new_loop (struct function *fn, struct loop *loop)
451 loop->num = number_of_loops (fn);
452 vec_safe_push (loops_for_fn (fn)->larray, loop);
455 /* Given LOOP structure with filled header and latch, find the body of the
456 corresponding loop and add it to loops tree. Insert the LOOP as a son of
457 outer. */
459 void
460 add_loop (struct loop *loop, struct loop *outer)
462 basic_block *bbs;
463 int i, n;
464 struct loop *subloop;
465 edge e;
466 edge_iterator ei;
468 /* Add it to loop structure. */
469 place_new_loop (cfun, loop);
470 flow_loop_tree_node_add (outer, loop);
472 /* Find its nodes. */
473 bbs = XNEWVEC (basic_block, n_basic_blocks_for_fn (cfun));
474 n = get_loop_body_with_size (loop, bbs, n_basic_blocks_for_fn (cfun));
476 for (i = 0; i < n; i++)
478 if (bbs[i]->loop_father == outer)
480 remove_bb_from_loops (bbs[i]);
481 add_bb_to_loop (bbs[i], loop);
482 continue;
485 loop->num_nodes++;
487 /* If we find a direct subloop of OUTER, move it to LOOP. */
488 subloop = bbs[i]->loop_father;
489 if (loop_outer (subloop) == outer
490 && subloop->header == bbs[i])
492 flow_loop_tree_node_remove (subloop);
493 flow_loop_tree_node_add (loop, subloop);
497 /* Update the information about loop exit edges. */
498 for (i = 0; i < n; i++)
500 FOR_EACH_EDGE (e, ei, bbs[i]->succs)
502 rescan_loop_exit (e, false, false);
506 free (bbs);
509 /* Multiply all frequencies in LOOP by NUM/DEN. */
511 void
512 scale_loop_frequencies (struct loop *loop, int num, int den)
514 basic_block *bbs;
516 bbs = get_loop_body (loop);
517 scale_bbs_frequencies_int (bbs, loop->num_nodes, num, den);
518 free (bbs);
521 /* Multiply all frequencies in LOOP by SCALE/REG_BR_PROB_BASE.
522 If ITERATION_BOUND is non-zero, scale even further if loop is predicted
523 to iterate too many times. */
525 void
526 scale_loop_profile (struct loop *loop, int scale, gcov_type iteration_bound)
528 gcov_type iterations = expected_loop_iterations_unbounded (loop);
529 edge e;
530 edge_iterator ei;
532 if (dump_file && (dump_flags & TDF_DETAILS))
533 fprintf (dump_file, ";; Scaling loop %i with scale %f, "
534 "bounding iterations to %i from guessed %i\n",
535 loop->num, (double)scale / REG_BR_PROB_BASE,
536 (int)iteration_bound, (int)iterations);
538 /* See if loop is predicted to iterate too many times. */
539 if (iteration_bound && iterations > 0
540 && apply_probability (iterations, scale) > iteration_bound)
542 /* Fixing loop profile for different trip count is not trivial; the exit
543 probabilities has to be updated to match and frequencies propagated down
544 to the loop body.
546 We fully update only the simple case of loop with single exit that is
547 either from the latch or BB just before latch and leads from BB with
548 simple conditional jump. This is OK for use in vectorizer. */
549 e = single_exit (loop);
550 if (e)
552 edge other_e;
553 int freq_delta;
554 gcov_type count_delta;
556 FOR_EACH_EDGE (other_e, ei, e->src->succs)
557 if (!(other_e->flags & (EDGE_ABNORMAL | EDGE_FAKE))
558 && e != other_e)
559 break;
561 /* Probability of exit must be 1/iterations. */
562 freq_delta = EDGE_FREQUENCY (e);
563 e->probability = REG_BR_PROB_BASE / iteration_bound;
564 other_e->probability = inverse_probability (e->probability);
565 freq_delta -= EDGE_FREQUENCY (e);
567 /* Adjust counts accordingly. */
568 count_delta = e->count;
569 e->count = apply_probability (e->src->count, e->probability);
570 other_e->count = apply_probability (e->src->count, other_e->probability);
571 count_delta -= e->count;
573 /* If latch exists, change its frequency and count, since we changed
574 probability of exit. Theoretically we should update everything from
575 source of exit edge to latch, but for vectorizer this is enough. */
576 if (loop->latch
577 && loop->latch != e->src)
579 loop->latch->frequency += freq_delta;
580 if (loop->latch->frequency < 0)
581 loop->latch->frequency = 0;
582 loop->latch->count += count_delta;
583 if (loop->latch->count < 0)
584 loop->latch->count = 0;
588 /* Roughly speaking we want to reduce the loop body profile by the
589 the difference of loop iterations. We however can do better if
590 we look at the actual profile, if it is available. */
591 scale = RDIV (iteration_bound * scale, iterations);
592 if (loop->header->count)
594 gcov_type count_in = 0;
596 FOR_EACH_EDGE (e, ei, loop->header->preds)
597 if (e->src != loop->latch)
598 count_in += e->count;
600 if (count_in != 0)
601 scale = GCOV_COMPUTE_SCALE (count_in * iteration_bound,
602 loop->header->count);
604 else if (loop->header->frequency)
606 int freq_in = 0;
608 FOR_EACH_EDGE (e, ei, loop->header->preds)
609 if (e->src != loop->latch)
610 freq_in += EDGE_FREQUENCY (e);
612 if (freq_in != 0)
613 scale = GCOV_COMPUTE_SCALE (freq_in * iteration_bound,
614 loop->header->frequency);
616 if (!scale)
617 scale = 1;
620 if (scale == REG_BR_PROB_BASE)
621 return;
623 /* Scale the actual probabilities. */
624 scale_loop_frequencies (loop, scale, REG_BR_PROB_BASE);
625 if (dump_file && (dump_flags & TDF_DETAILS))
626 fprintf (dump_file, ";; guessed iterations are now %i\n",
627 (int)expected_loop_iterations_unbounded (loop));
630 /* Recompute dominance information for basic blocks outside LOOP. */
632 static void
633 update_dominators_in_loop (struct loop *loop)
635 vec<basic_block> dom_bbs = vNULL;
636 sbitmap seen;
637 basic_block *body;
638 unsigned i;
640 seen = sbitmap_alloc (last_basic_block_for_fn (cfun));
641 bitmap_clear (seen);
642 body = get_loop_body (loop);
644 for (i = 0; i < loop->num_nodes; i++)
645 bitmap_set_bit (seen, body[i]->index);
647 for (i = 0; i < loop->num_nodes; i++)
649 basic_block ldom;
651 for (ldom = first_dom_son (CDI_DOMINATORS, body[i]);
652 ldom;
653 ldom = next_dom_son (CDI_DOMINATORS, ldom))
654 if (!bitmap_bit_p (seen, ldom->index))
656 bitmap_set_bit (seen, ldom->index);
657 dom_bbs.safe_push (ldom);
661 iterate_fix_dominators (CDI_DOMINATORS, dom_bbs, false);
662 free (body);
663 free (seen);
664 dom_bbs.release ();
667 /* Creates an if region as shown above. CONDITION is used to create
668 the test for the if.
671 | ------------- -------------
672 | | pred_bb | | pred_bb |
673 | ------------- -------------
674 | | |
675 | | | ENTRY_EDGE
676 | | ENTRY_EDGE V
677 | | ====> -------------
678 | | | cond_bb |
679 | | | CONDITION |
680 | | -------------
681 | V / \
682 | ------------- e_false / \ e_true
683 | | succ_bb | V V
684 | ------------- ----------- -----------
685 | | false_bb | | true_bb |
686 | ----------- -----------
687 | \ /
688 | \ /
689 | V V
690 | -------------
691 | | join_bb |
692 | -------------
693 | | exit_edge (result)
695 | -----------
696 | | succ_bb |
697 | -----------
701 edge
702 create_empty_if_region_on_edge (edge entry_edge, tree condition)
705 basic_block cond_bb, true_bb, false_bb, join_bb;
706 edge e_true, e_false, exit_edge;
707 gcond *cond_stmt;
708 tree simple_cond;
709 gimple_stmt_iterator gsi;
711 cond_bb = split_edge (entry_edge);
713 /* Insert condition in cond_bb. */
714 gsi = gsi_last_bb (cond_bb);
715 simple_cond =
716 force_gimple_operand_gsi (&gsi, condition, true, NULL,
717 false, GSI_NEW_STMT);
718 cond_stmt = gimple_build_cond_from_tree (simple_cond, NULL_TREE, NULL_TREE);
719 gsi = gsi_last_bb (cond_bb);
720 gsi_insert_after (&gsi, cond_stmt, GSI_NEW_STMT);
722 join_bb = split_edge (single_succ_edge (cond_bb));
724 e_true = single_succ_edge (cond_bb);
725 true_bb = split_edge (e_true);
727 e_false = make_edge (cond_bb, join_bb, 0);
728 false_bb = split_edge (e_false);
730 e_true->flags &= ~EDGE_FALLTHRU;
731 e_true->flags |= EDGE_TRUE_VALUE;
732 e_false->flags &= ~EDGE_FALLTHRU;
733 e_false->flags |= EDGE_FALSE_VALUE;
735 set_immediate_dominator (CDI_DOMINATORS, cond_bb, entry_edge->src);
736 set_immediate_dominator (CDI_DOMINATORS, true_bb, cond_bb);
737 set_immediate_dominator (CDI_DOMINATORS, false_bb, cond_bb);
738 set_immediate_dominator (CDI_DOMINATORS, join_bb, cond_bb);
740 exit_edge = single_succ_edge (join_bb);
742 if (single_pred_p (exit_edge->dest))
743 set_immediate_dominator (CDI_DOMINATORS, exit_edge->dest, join_bb);
745 return exit_edge;
748 /* create_empty_loop_on_edge
750 | - pred_bb - ------ pred_bb ------
751 | | | | iv0 = initial_value |
752 | -----|----- ---------|-----------
753 | | ______ | entry_edge
754 | | entry_edge / | |
755 | | ====> | -V---V- loop_header -------------
756 | V | | iv_before = phi (iv0, iv_after) |
757 | - succ_bb - | ---|-----------------------------
758 | | | | |
759 | ----------- | ---V--- loop_body ---------------
760 | | | iv_after = iv_before + stride |
761 | | | if (iv_before < upper_bound) |
762 | | ---|--------------\--------------
763 | | | \ exit_e
764 | | V \
765 | | - loop_latch - V- succ_bb -
766 | | | | | |
767 | | /------------- -----------
768 | \ ___ /
770 Creates an empty loop as shown above, the IV_BEFORE is the SSA_NAME
771 that is used before the increment of IV. IV_BEFORE should be used for
772 adding code to the body that uses the IV. OUTER is the outer loop in
773 which the new loop should be inserted.
775 Both INITIAL_VALUE and UPPER_BOUND expressions are gimplified and
776 inserted on the loop entry edge. This implies that this function
777 should be used only when the UPPER_BOUND expression is a loop
778 invariant. */
780 struct loop *
781 create_empty_loop_on_edge (edge entry_edge,
782 tree initial_value,
783 tree stride, tree upper_bound,
784 tree iv,
785 tree *iv_before,
786 tree *iv_after,
787 struct loop *outer)
789 basic_block loop_header, loop_latch, succ_bb, pred_bb;
790 struct loop *loop;
791 gimple_stmt_iterator gsi;
792 gimple_seq stmts;
793 gcond *cond_expr;
794 tree exit_test;
795 edge exit_e;
796 int prob;
798 gcc_assert (entry_edge && initial_value && stride && upper_bound && iv);
800 /* Create header, latch and wire up the loop. */
801 pred_bb = entry_edge->src;
802 loop_header = split_edge (entry_edge);
803 loop_latch = split_edge (single_succ_edge (loop_header));
804 succ_bb = single_succ (loop_latch);
805 make_edge (loop_header, succ_bb, 0);
806 redirect_edge_succ_nodup (single_succ_edge (loop_latch), loop_header);
808 /* Set immediate dominator information. */
809 set_immediate_dominator (CDI_DOMINATORS, loop_header, pred_bb);
810 set_immediate_dominator (CDI_DOMINATORS, loop_latch, loop_header);
811 set_immediate_dominator (CDI_DOMINATORS, succ_bb, loop_header);
813 /* Initialize a loop structure and put it in a loop hierarchy. */
814 loop = alloc_loop ();
815 loop->header = loop_header;
816 loop->latch = loop_latch;
817 add_loop (loop, outer);
819 /* TODO: Fix frequencies and counts. */
820 prob = REG_BR_PROB_BASE / 2;
822 scale_loop_frequencies (loop, REG_BR_PROB_BASE - prob, REG_BR_PROB_BASE);
824 /* Update dominators. */
825 update_dominators_in_loop (loop);
827 /* Modify edge flags. */
828 exit_e = single_exit (loop);
829 exit_e->flags = EDGE_LOOP_EXIT | EDGE_FALSE_VALUE;
830 single_pred_edge (loop_latch)->flags = EDGE_TRUE_VALUE;
832 /* Construct IV code in loop. */
833 initial_value = force_gimple_operand (initial_value, &stmts, true, iv);
834 if (stmts)
836 gsi_insert_seq_on_edge (loop_preheader_edge (loop), stmts);
837 gsi_commit_edge_inserts ();
840 upper_bound = force_gimple_operand (upper_bound, &stmts, true, NULL);
841 if (stmts)
843 gsi_insert_seq_on_edge (loop_preheader_edge (loop), stmts);
844 gsi_commit_edge_inserts ();
847 gsi = gsi_last_bb (loop_header);
848 create_iv (initial_value, stride, iv, loop, &gsi, false,
849 iv_before, iv_after);
851 /* Insert loop exit condition. */
852 cond_expr = gimple_build_cond
853 (LT_EXPR, *iv_before, upper_bound, NULL_TREE, NULL_TREE);
855 exit_test = gimple_cond_lhs (cond_expr);
856 exit_test = force_gimple_operand_gsi (&gsi, exit_test, true, NULL,
857 false, GSI_NEW_STMT);
858 gimple_cond_set_lhs (cond_expr, exit_test);
859 gsi = gsi_last_bb (exit_e->src);
860 gsi_insert_after (&gsi, cond_expr, GSI_NEW_STMT);
862 split_block_after_labels (loop_header);
864 return loop;
867 /* Make area between HEADER_EDGE and LATCH_EDGE a loop by connecting
868 latch to header and update loop tree and dominators
869 accordingly. Everything between them plus LATCH_EDGE destination must
870 be dominated by HEADER_EDGE destination, and back-reachable from
871 LATCH_EDGE source. HEADER_EDGE is redirected to basic block SWITCH_BB,
872 FALSE_EDGE of SWITCH_BB to original destination of HEADER_EDGE and
873 TRUE_EDGE of SWITCH_BB to original destination of LATCH_EDGE.
874 Returns the newly created loop. Frequencies and counts in the new loop
875 are scaled by FALSE_SCALE and in the old one by TRUE_SCALE. */
877 struct loop *
878 loopify (edge latch_edge, edge header_edge,
879 basic_block switch_bb, edge true_edge, edge false_edge,
880 bool redirect_all_edges, unsigned true_scale, unsigned false_scale)
882 basic_block succ_bb = latch_edge->dest;
883 basic_block pred_bb = header_edge->src;
884 struct loop *loop = alloc_loop ();
885 struct loop *outer = loop_outer (succ_bb->loop_father);
886 int freq;
887 gcov_type cnt;
888 edge e;
889 edge_iterator ei;
891 loop->header = header_edge->dest;
892 loop->latch = latch_edge->src;
894 freq = EDGE_FREQUENCY (header_edge);
895 cnt = header_edge->count;
897 /* Redirect edges. */
898 loop_redirect_edge (latch_edge, loop->header);
899 loop_redirect_edge (true_edge, succ_bb);
901 /* During loop versioning, one of the switch_bb edge is already properly
902 set. Do not redirect it again unless redirect_all_edges is true. */
903 if (redirect_all_edges)
905 loop_redirect_edge (header_edge, switch_bb);
906 loop_redirect_edge (false_edge, loop->header);
908 /* Update dominators. */
909 set_immediate_dominator (CDI_DOMINATORS, switch_bb, pred_bb);
910 set_immediate_dominator (CDI_DOMINATORS, loop->header, switch_bb);
913 set_immediate_dominator (CDI_DOMINATORS, succ_bb, switch_bb);
915 /* Compute new loop. */
916 add_loop (loop, outer);
918 /* Add switch_bb to appropriate loop. */
919 if (switch_bb->loop_father)
920 remove_bb_from_loops (switch_bb);
921 add_bb_to_loop (switch_bb, outer);
923 /* Fix frequencies. */
924 if (redirect_all_edges)
926 switch_bb->frequency = freq;
927 switch_bb->count = cnt;
928 FOR_EACH_EDGE (e, ei, switch_bb->succs)
930 e->count = apply_probability (switch_bb->count, e->probability);
933 scale_loop_frequencies (loop, false_scale, REG_BR_PROB_BASE);
934 scale_loop_frequencies (succ_bb->loop_father, true_scale, REG_BR_PROB_BASE);
935 update_dominators_in_loop (loop);
937 return loop;
940 /* Remove the latch edge of a LOOP and update loops to indicate that
941 the LOOP was removed. After this function, original loop latch will
942 have no successor, which caller is expected to fix somehow.
944 If this may cause the information about irreducible regions to become
945 invalid, IRRED_INVALIDATED is set to true.
947 LOOP_CLOSED_SSA_INVALIDATED, if non-NULL, is a bitmap where we store
948 basic blocks that had non-trivial update on their loop_father.*/
950 void
951 unloop (struct loop *loop, bool *irred_invalidated,
952 bitmap loop_closed_ssa_invalidated)
954 basic_block *body;
955 struct loop *ploop;
956 unsigned i, n;
957 basic_block latch = loop->latch;
958 bool dummy = false;
960 if (loop_preheader_edge (loop)->flags & EDGE_IRREDUCIBLE_LOOP)
961 *irred_invalidated = true;
963 /* This is relatively straightforward. The dominators are unchanged, as
964 loop header dominates loop latch, so the only thing we have to care of
965 is the placement of loops and basic blocks inside the loop tree. We
966 move them all to the loop->outer, and then let fix_bb_placements do
967 its work. */
969 body = get_loop_body (loop);
970 n = loop->num_nodes;
971 for (i = 0; i < n; i++)
972 if (body[i]->loop_father == loop)
974 remove_bb_from_loops (body[i]);
975 add_bb_to_loop (body[i], loop_outer (loop));
977 free (body);
979 while (loop->inner)
981 ploop = loop->inner;
982 flow_loop_tree_node_remove (ploop);
983 flow_loop_tree_node_add (loop_outer (loop), ploop);
986 /* Remove the loop and free its data. */
987 delete_loop (loop);
989 remove_edge (single_succ_edge (latch));
991 /* We do not pass IRRED_INVALIDATED to fix_bb_placements here, as even if
992 there is an irreducible region inside the cancelled loop, the flags will
993 be still correct. */
994 fix_bb_placements (latch, &dummy, loop_closed_ssa_invalidated);
997 /* Fix placement of superloops of LOOP inside loop tree, i.e. ensure that
998 condition stated in description of fix_loop_placement holds for them.
999 It is used in case when we removed some edges coming out of LOOP, which
1000 may cause the right placement of LOOP inside loop tree to change.
1002 IRRED_INVALIDATED is set to true if a change in the loop structures might
1003 invalidate the information about irreducible regions. */
1005 static void
1006 fix_loop_placements (struct loop *loop, bool *irred_invalidated)
1008 struct loop *outer;
1010 while (loop_outer (loop))
1012 outer = loop_outer (loop);
1013 if (!fix_loop_placement (loop, irred_invalidated))
1014 break;
1016 /* Changing the placement of a loop in the loop tree may alter the
1017 validity of condition 2) of the description of fix_bb_placement
1018 for its preheader, because the successor is the header and belongs
1019 to the loop. So call fix_bb_placements to fix up the placement
1020 of the preheader and (possibly) of its predecessors. */
1021 fix_bb_placements (loop_preheader_edge (loop)->src,
1022 irred_invalidated, NULL);
1023 loop = outer;
1027 /* Duplicate loop bounds and other information we store about
1028 the loop into its duplicate. */
1030 void
1031 copy_loop_info (struct loop *loop, struct loop *target)
1033 gcc_checking_assert (!target->any_upper_bound && !target->any_estimate);
1034 target->any_upper_bound = loop->any_upper_bound;
1035 target->nb_iterations_upper_bound = loop->nb_iterations_upper_bound;
1036 target->any_estimate = loop->any_estimate;
1037 target->nb_iterations_estimate = loop->nb_iterations_estimate;
1038 target->estimate_state = loop->estimate_state;
1039 target->warned_aggressive_loop_optimizations
1040 |= loop->warned_aggressive_loop_optimizations;
1043 /* Copies copy of LOOP as subloop of TARGET loop, placing newly
1044 created loop into loops structure. */
1045 struct loop *
1046 duplicate_loop (struct loop *loop, struct loop *target)
1048 struct loop *cloop;
1049 cloop = alloc_loop ();
1050 place_new_loop (cfun, cloop);
1052 copy_loop_info (loop, cloop);
1054 /* Mark the new loop as copy of LOOP. */
1055 set_loop_copy (loop, cloop);
1057 /* Add it to target. */
1058 flow_loop_tree_node_add (target, cloop);
1060 return cloop;
1063 /* Copies structure of subloops of LOOP into TARGET loop, placing
1064 newly created loops into loop tree. */
1065 void
1066 duplicate_subloops (struct loop *loop, struct loop *target)
1068 struct loop *aloop, *cloop;
1070 for (aloop = loop->inner; aloop; aloop = aloop->next)
1072 cloop = duplicate_loop (aloop, target);
1073 duplicate_subloops (aloop, cloop);
1077 /* Copies structure of subloops of N loops, stored in array COPIED_LOOPS,
1078 into TARGET loop, placing newly created loops into loop tree. */
1079 static void
1080 copy_loops_to (struct loop **copied_loops, int n, struct loop *target)
1082 struct loop *aloop;
1083 int i;
1085 for (i = 0; i < n; i++)
1087 aloop = duplicate_loop (copied_loops[i], target);
1088 duplicate_subloops (copied_loops[i], aloop);
1092 /* Redirects edge E to basic block DEST. */
1093 static void
1094 loop_redirect_edge (edge e, basic_block dest)
1096 if (e->dest == dest)
1097 return;
1099 redirect_edge_and_branch_force (e, dest);
1102 /* Check whether LOOP's body can be duplicated. */
1103 bool
1104 can_duplicate_loop_p (const struct loop *loop)
1106 int ret;
1107 basic_block *bbs = get_loop_body (loop);
1109 ret = can_copy_bbs_p (bbs, loop->num_nodes);
1110 free (bbs);
1112 return ret;
1115 /* Sets probability and count of edge E to zero. The probability and count
1116 is redistributed evenly to the remaining edges coming from E->src. */
1118 static void
1119 set_zero_probability (edge e)
1121 basic_block bb = e->src;
1122 edge_iterator ei;
1123 edge ae, last = NULL;
1124 unsigned n = EDGE_COUNT (bb->succs);
1125 gcov_type cnt = e->count, cnt1;
1126 unsigned prob = e->probability, prob1;
1128 gcc_assert (n > 1);
1129 cnt1 = cnt / (n - 1);
1130 prob1 = prob / (n - 1);
1132 FOR_EACH_EDGE (ae, ei, bb->succs)
1134 if (ae == e)
1135 continue;
1137 ae->probability += prob1;
1138 ae->count += cnt1;
1139 last = ae;
1142 /* Move the rest to one of the edges. */
1143 last->probability += prob % (n - 1);
1144 last->count += cnt % (n - 1);
1146 e->probability = 0;
1147 e->count = 0;
1150 /* Duplicates body of LOOP to given edge E NDUPL times. Takes care of updating
1151 loop structure and dominators. E's destination must be LOOP header for
1152 this to work, i.e. it must be entry or latch edge of this loop; these are
1153 unique, as the loops must have preheaders for this function to work
1154 correctly (in case E is latch, the function unrolls the loop, if E is entry
1155 edge, it peels the loop). Store edges created by copying ORIG edge from
1156 copies corresponding to set bits in WONT_EXIT bitmap (bit 0 corresponds to
1157 original LOOP body, the other copies are numbered in order given by control
1158 flow through them) into TO_REMOVE array. Returns false if duplication is
1159 impossible. */
1161 bool
1162 duplicate_loop_to_header_edge (struct loop *loop, edge e,
1163 unsigned int ndupl, sbitmap wont_exit,
1164 edge orig, vec<edge> *to_remove,
1165 int flags)
1167 struct loop *target, *aloop;
1168 struct loop **orig_loops;
1169 unsigned n_orig_loops;
1170 basic_block header = loop->header, latch = loop->latch;
1171 basic_block *new_bbs, *bbs, *first_active;
1172 basic_block new_bb, bb, first_active_latch = NULL;
1173 edge ae, latch_edge;
1174 edge spec_edges[2], new_spec_edges[2];
1175 #define SE_LATCH 0
1176 #define SE_ORIG 1
1177 unsigned i, j, n;
1178 int is_latch = (latch == e->src);
1179 int scale_act = 0, *scale_step = NULL, scale_main = 0;
1180 int scale_after_exit = 0;
1181 int p, freq_in, freq_le, freq_out_orig;
1182 int prob_pass_thru, prob_pass_wont_exit, prob_pass_main;
1183 int add_irreducible_flag;
1184 basic_block place_after;
1185 bitmap bbs_to_scale = NULL;
1186 bitmap_iterator bi;
1188 gcc_assert (e->dest == loop->header);
1189 gcc_assert (ndupl > 0);
1191 if (orig)
1193 /* Orig must be edge out of the loop. */
1194 gcc_assert (flow_bb_inside_loop_p (loop, orig->src));
1195 gcc_assert (!flow_bb_inside_loop_p (loop, orig->dest));
1198 n = loop->num_nodes;
1199 bbs = get_loop_body_in_dom_order (loop);
1200 gcc_assert (bbs[0] == loop->header);
1201 gcc_assert (bbs[n - 1] == loop->latch);
1203 /* Check whether duplication is possible. */
1204 if (!can_copy_bbs_p (bbs, loop->num_nodes))
1206 free (bbs);
1207 return false;
1209 new_bbs = XNEWVEC (basic_block, loop->num_nodes);
1211 /* In case we are doing loop peeling and the loop is in the middle of
1212 irreducible region, the peeled copies will be inside it too. */
1213 add_irreducible_flag = e->flags & EDGE_IRREDUCIBLE_LOOP;
1214 gcc_assert (!is_latch || !add_irreducible_flag);
1216 /* Find edge from latch. */
1217 latch_edge = loop_latch_edge (loop);
1219 if (flags & DLTHE_FLAG_UPDATE_FREQ)
1221 /* Calculate coefficients by that we have to scale frequencies
1222 of duplicated loop bodies. */
1223 freq_in = header->frequency;
1224 freq_le = EDGE_FREQUENCY (latch_edge);
1225 if (freq_in == 0)
1226 freq_in = 1;
1227 if (freq_in < freq_le)
1228 freq_in = freq_le;
1229 freq_out_orig = orig ? EDGE_FREQUENCY (orig) : freq_in - freq_le;
1230 if (freq_out_orig > freq_in - freq_le)
1231 freq_out_orig = freq_in - freq_le;
1232 prob_pass_thru = RDIV (REG_BR_PROB_BASE * freq_le, freq_in);
1233 prob_pass_wont_exit =
1234 RDIV (REG_BR_PROB_BASE * (freq_le + freq_out_orig), freq_in);
1236 if (orig
1237 && REG_BR_PROB_BASE - orig->probability != 0)
1239 /* The blocks that are dominated by a removed exit edge ORIG have
1240 frequencies scaled by this. */
1241 scale_after_exit
1242 = GCOV_COMPUTE_SCALE (REG_BR_PROB_BASE,
1243 REG_BR_PROB_BASE - orig->probability);
1244 bbs_to_scale = BITMAP_ALLOC (NULL);
1245 for (i = 0; i < n; i++)
1247 if (bbs[i] != orig->src
1248 && dominated_by_p (CDI_DOMINATORS, bbs[i], orig->src))
1249 bitmap_set_bit (bbs_to_scale, i);
1253 scale_step = XNEWVEC (int, ndupl);
1255 for (i = 1; i <= ndupl; i++)
1256 scale_step[i - 1] = bitmap_bit_p (wont_exit, i)
1257 ? prob_pass_wont_exit
1258 : prob_pass_thru;
1260 /* Complete peeling is special as the probability of exit in last
1261 copy becomes 1. */
1262 if (flags & DLTHE_FLAG_COMPLETTE_PEEL)
1264 int wanted_freq = EDGE_FREQUENCY (e);
1266 if (wanted_freq > freq_in)
1267 wanted_freq = freq_in;
1269 gcc_assert (!is_latch);
1270 /* First copy has frequency of incoming edge. Each subsequent
1271 frequency should be reduced by prob_pass_wont_exit. Caller
1272 should've managed the flags so all except for original loop
1273 has won't exist set. */
1274 scale_act = GCOV_COMPUTE_SCALE (wanted_freq, freq_in);
1275 /* Now simulate the duplication adjustments and compute header
1276 frequency of the last copy. */
1277 for (i = 0; i < ndupl; i++)
1278 wanted_freq = combine_probabilities (wanted_freq, scale_step[i]);
1279 scale_main = GCOV_COMPUTE_SCALE (wanted_freq, freq_in);
1281 else if (is_latch)
1283 prob_pass_main = bitmap_bit_p (wont_exit, 0)
1284 ? prob_pass_wont_exit
1285 : prob_pass_thru;
1286 p = prob_pass_main;
1287 scale_main = REG_BR_PROB_BASE;
1288 for (i = 0; i < ndupl; i++)
1290 scale_main += p;
1291 p = combine_probabilities (p, scale_step[i]);
1293 scale_main = GCOV_COMPUTE_SCALE (REG_BR_PROB_BASE, scale_main);
1294 scale_act = combine_probabilities (scale_main, prob_pass_main);
1296 else
1298 scale_main = REG_BR_PROB_BASE;
1299 for (i = 0; i < ndupl; i++)
1300 scale_main = combine_probabilities (scale_main, scale_step[i]);
1301 scale_act = REG_BR_PROB_BASE - prob_pass_thru;
1303 for (i = 0; i < ndupl; i++)
1304 gcc_assert (scale_step[i] >= 0 && scale_step[i] <= REG_BR_PROB_BASE);
1305 gcc_assert (scale_main >= 0 && scale_main <= REG_BR_PROB_BASE
1306 && scale_act >= 0 && scale_act <= REG_BR_PROB_BASE);
1309 /* Loop the new bbs will belong to. */
1310 target = e->src->loop_father;
1312 /* Original loops. */
1313 n_orig_loops = 0;
1314 for (aloop = loop->inner; aloop; aloop = aloop->next)
1315 n_orig_loops++;
1316 orig_loops = XNEWVEC (struct loop *, n_orig_loops);
1317 for (aloop = loop->inner, i = 0; aloop; aloop = aloop->next, i++)
1318 orig_loops[i] = aloop;
1320 set_loop_copy (loop, target);
1322 first_active = XNEWVEC (basic_block, n);
1323 if (is_latch)
1325 memcpy (first_active, bbs, n * sizeof (basic_block));
1326 first_active_latch = latch;
1329 spec_edges[SE_ORIG] = orig;
1330 spec_edges[SE_LATCH] = latch_edge;
1332 place_after = e->src;
1333 for (j = 0; j < ndupl; j++)
1335 /* Copy loops. */
1336 copy_loops_to (orig_loops, n_orig_loops, target);
1338 /* Copy bbs. */
1339 copy_bbs (bbs, n, new_bbs, spec_edges, 2, new_spec_edges, loop,
1340 place_after, true);
1341 place_after = new_spec_edges[SE_LATCH]->src;
1343 if (flags & DLTHE_RECORD_COPY_NUMBER)
1344 for (i = 0; i < n; i++)
1346 gcc_assert (!new_bbs[i]->aux);
1347 new_bbs[i]->aux = (void *)(size_t)(j + 1);
1350 /* Note whether the blocks and edges belong to an irreducible loop. */
1351 if (add_irreducible_flag)
1353 for (i = 0; i < n; i++)
1354 new_bbs[i]->flags |= BB_DUPLICATED;
1355 for (i = 0; i < n; i++)
1357 edge_iterator ei;
1358 new_bb = new_bbs[i];
1359 if (new_bb->loop_father == target)
1360 new_bb->flags |= BB_IRREDUCIBLE_LOOP;
1362 FOR_EACH_EDGE (ae, ei, new_bb->succs)
1363 if ((ae->dest->flags & BB_DUPLICATED)
1364 && (ae->src->loop_father == target
1365 || ae->dest->loop_father == target))
1366 ae->flags |= EDGE_IRREDUCIBLE_LOOP;
1368 for (i = 0; i < n; i++)
1369 new_bbs[i]->flags &= ~BB_DUPLICATED;
1372 /* Redirect the special edges. */
1373 if (is_latch)
1375 redirect_edge_and_branch_force (latch_edge, new_bbs[0]);
1376 redirect_edge_and_branch_force (new_spec_edges[SE_LATCH],
1377 loop->header);
1378 set_immediate_dominator (CDI_DOMINATORS, new_bbs[0], latch);
1379 latch = loop->latch = new_bbs[n - 1];
1380 e = latch_edge = new_spec_edges[SE_LATCH];
1382 else
1384 redirect_edge_and_branch_force (new_spec_edges[SE_LATCH],
1385 loop->header);
1386 redirect_edge_and_branch_force (e, new_bbs[0]);
1387 set_immediate_dominator (CDI_DOMINATORS, new_bbs[0], e->src);
1388 e = new_spec_edges[SE_LATCH];
1391 /* Record exit edge in this copy. */
1392 if (orig && bitmap_bit_p (wont_exit, j + 1))
1394 if (to_remove)
1395 to_remove->safe_push (new_spec_edges[SE_ORIG]);
1396 set_zero_probability (new_spec_edges[SE_ORIG]);
1398 /* Scale the frequencies of the blocks dominated by the exit. */
1399 if (bbs_to_scale)
1401 EXECUTE_IF_SET_IN_BITMAP (bbs_to_scale, 0, i, bi)
1403 scale_bbs_frequencies_int (new_bbs + i, 1, scale_after_exit,
1404 REG_BR_PROB_BASE);
1409 /* Record the first copy in the control flow order if it is not
1410 the original loop (i.e. in case of peeling). */
1411 if (!first_active_latch)
1413 memcpy (first_active, new_bbs, n * sizeof (basic_block));
1414 first_active_latch = new_bbs[n - 1];
1417 /* Set counts and frequencies. */
1418 if (flags & DLTHE_FLAG_UPDATE_FREQ)
1420 scale_bbs_frequencies_int (new_bbs, n, scale_act, REG_BR_PROB_BASE);
1421 scale_act = combine_probabilities (scale_act, scale_step[j]);
1424 free (new_bbs);
1425 free (orig_loops);
1427 /* Record the exit edge in the original loop body, and update the frequencies. */
1428 if (orig && bitmap_bit_p (wont_exit, 0))
1430 if (to_remove)
1431 to_remove->safe_push (orig);
1432 set_zero_probability (orig);
1434 /* Scale the frequencies of the blocks dominated by the exit. */
1435 if (bbs_to_scale)
1437 EXECUTE_IF_SET_IN_BITMAP (bbs_to_scale, 0, i, bi)
1439 scale_bbs_frequencies_int (bbs + i, 1, scale_after_exit,
1440 REG_BR_PROB_BASE);
1445 /* Update the original loop. */
1446 if (!is_latch)
1447 set_immediate_dominator (CDI_DOMINATORS, e->dest, e->src);
1448 if (flags & DLTHE_FLAG_UPDATE_FREQ)
1450 scale_bbs_frequencies_int (bbs, n, scale_main, REG_BR_PROB_BASE);
1451 free (scale_step);
1454 /* Update dominators of outer blocks if affected. */
1455 for (i = 0; i < n; i++)
1457 basic_block dominated, dom_bb;
1458 vec<basic_block> dom_bbs;
1459 unsigned j;
1461 bb = bbs[i];
1462 bb->aux = 0;
1464 dom_bbs = get_dominated_by (CDI_DOMINATORS, bb);
1465 FOR_EACH_VEC_ELT (dom_bbs, j, dominated)
1467 if (flow_bb_inside_loop_p (loop, dominated))
1468 continue;
1469 dom_bb = nearest_common_dominator (
1470 CDI_DOMINATORS, first_active[i], first_active_latch);
1471 set_immediate_dominator (CDI_DOMINATORS, dominated, dom_bb);
1473 dom_bbs.release ();
1475 free (first_active);
1477 free (bbs);
1478 BITMAP_FREE (bbs_to_scale);
1480 return true;
1483 /* A callback for make_forwarder block, to redirect all edges except for
1484 MFB_KJ_EDGE to the entry part. E is the edge for that we should decide
1485 whether to redirect it. */
1487 edge mfb_kj_edge;
1488 bool
1489 mfb_keep_just (edge e)
1491 return e != mfb_kj_edge;
1494 /* True when a candidate preheader BLOCK has predecessors from LOOP. */
1496 static bool
1497 has_preds_from_loop (basic_block block, struct loop *loop)
1499 edge e;
1500 edge_iterator ei;
1502 FOR_EACH_EDGE (e, ei, block->preds)
1503 if (e->src->loop_father == loop)
1504 return true;
1505 return false;
1508 /* Creates a pre-header for a LOOP. Returns newly created block. Unless
1509 CP_SIMPLE_PREHEADERS is set in FLAGS, we only force LOOP to have single
1510 entry; otherwise we also force preheader block to have only one successor.
1511 When CP_FALLTHRU_PREHEADERS is set in FLAGS, we force the preheader block
1512 to be a fallthru predecessor to the loop header and to have only
1513 predecessors from outside of the loop.
1514 The function also updates dominators. */
1516 basic_block
1517 create_preheader (struct loop *loop, int flags)
1519 edge e, fallthru;
1520 basic_block dummy;
1521 int nentry = 0;
1522 bool irred = false;
1523 bool latch_edge_was_fallthru;
1524 edge one_succ_pred = NULL, single_entry = NULL;
1525 edge_iterator ei;
1527 FOR_EACH_EDGE (e, ei, loop->header->preds)
1529 if (e->src == loop->latch)
1530 continue;
1531 irred |= (e->flags & EDGE_IRREDUCIBLE_LOOP) != 0;
1532 nentry++;
1533 single_entry = e;
1534 if (single_succ_p (e->src))
1535 one_succ_pred = e;
1537 gcc_assert (nentry);
1538 if (nentry == 1)
1540 bool need_forwarder_block = false;
1542 /* We do not allow entry block to be the loop preheader, since we
1543 cannot emit code there. */
1544 if (single_entry->src == ENTRY_BLOCK_PTR_FOR_FN (cfun))
1545 need_forwarder_block = true;
1546 else
1548 /* If we want simple preheaders, also force the preheader to have
1549 just a single successor. */
1550 if ((flags & CP_SIMPLE_PREHEADERS)
1551 && !single_succ_p (single_entry->src))
1552 need_forwarder_block = true;
1553 /* If we want fallthru preheaders, also create forwarder block when
1554 preheader ends with a jump or has predecessors from loop. */
1555 else if ((flags & CP_FALLTHRU_PREHEADERS)
1556 && (JUMP_P (BB_END (single_entry->src))
1557 || has_preds_from_loop (single_entry->src, loop)))
1558 need_forwarder_block = true;
1560 if (! need_forwarder_block)
1561 return NULL;
1564 mfb_kj_edge = loop_latch_edge (loop);
1565 latch_edge_was_fallthru = (mfb_kj_edge->flags & EDGE_FALLTHRU) != 0;
1566 fallthru = make_forwarder_block (loop->header, mfb_keep_just, NULL);
1567 dummy = fallthru->src;
1568 loop->header = fallthru->dest;
1570 /* Try to be clever in placing the newly created preheader. The idea is to
1571 avoid breaking any "fallthruness" relationship between blocks.
1573 The preheader was created just before the header and all incoming edges
1574 to the header were redirected to the preheader, except the latch edge.
1575 So the only problematic case is when this latch edge was a fallthru
1576 edge: it is not anymore after the preheader creation so we have broken
1577 the fallthruness. We're therefore going to look for a better place. */
1578 if (latch_edge_was_fallthru)
1580 if (one_succ_pred)
1581 e = one_succ_pred;
1582 else
1583 e = EDGE_PRED (dummy, 0);
1585 move_block_after (dummy, e->src);
1588 if (irred)
1590 dummy->flags |= BB_IRREDUCIBLE_LOOP;
1591 single_succ_edge (dummy)->flags |= EDGE_IRREDUCIBLE_LOOP;
1594 if (dump_file)
1595 fprintf (dump_file, "Created preheader block for loop %i\n",
1596 loop->num);
1598 if (flags & CP_FALLTHRU_PREHEADERS)
1599 gcc_assert ((single_succ_edge (dummy)->flags & EDGE_FALLTHRU)
1600 && !JUMP_P (BB_END (dummy)));
1602 return dummy;
1605 /* Create preheaders for each loop; for meaning of FLAGS see create_preheader. */
1607 void
1608 create_preheaders (int flags)
1610 struct loop *loop;
1612 if (!current_loops)
1613 return;
1615 FOR_EACH_LOOP (loop, 0)
1616 create_preheader (loop, flags);
1617 loops_state_set (LOOPS_HAVE_PREHEADERS);
1620 /* Forces all loop latches to have only single successor. */
1622 void
1623 force_single_succ_latches (void)
1625 struct loop *loop;
1626 edge e;
1628 FOR_EACH_LOOP (loop, 0)
1630 if (loop->latch != loop->header && single_succ_p (loop->latch))
1631 continue;
1633 e = find_edge (loop->latch, loop->header);
1634 gcc_checking_assert (e != NULL);
1636 split_edge (e);
1638 loops_state_set (LOOPS_HAVE_SIMPLE_LATCHES);
1641 /* This function is called from loop_version. It splits the entry edge
1642 of the loop we want to version, adds the versioning condition, and
1643 adjust the edges to the two versions of the loop appropriately.
1644 e is an incoming edge. Returns the basic block containing the
1645 condition.
1647 --- edge e ---- > [second_head]
1649 Split it and insert new conditional expression and adjust edges.
1651 --- edge e ---> [cond expr] ---> [first_head]
1653 +---------> [second_head]
1655 THEN_PROB is the probability of then branch of the condition. */
1657 static basic_block
1658 lv_adjust_loop_entry_edge (basic_block first_head, basic_block second_head,
1659 edge e, void *cond_expr, unsigned then_prob)
1661 basic_block new_head = NULL;
1662 edge e1;
1664 gcc_assert (e->dest == second_head);
1666 /* Split edge 'e'. This will create a new basic block, where we can
1667 insert conditional expr. */
1668 new_head = split_edge (e);
1670 lv_add_condition_to_bb (first_head, second_head, new_head,
1671 cond_expr);
1673 /* Don't set EDGE_TRUE_VALUE in RTL mode, as it's invalid there. */
1674 e = single_succ_edge (new_head);
1675 e1 = make_edge (new_head, first_head,
1676 current_ir_type () == IR_GIMPLE ? EDGE_TRUE_VALUE : 0);
1677 e1->probability = then_prob;
1678 e->probability = REG_BR_PROB_BASE - then_prob;
1679 e1->count = apply_probability (e->count, e1->probability);
1680 e->count = apply_probability (e->count, e->probability);
1682 set_immediate_dominator (CDI_DOMINATORS, first_head, new_head);
1683 set_immediate_dominator (CDI_DOMINATORS, second_head, new_head);
1685 /* Adjust loop header phi nodes. */
1686 lv_adjust_loop_header_phi (first_head, second_head, new_head, e1);
1688 return new_head;
1691 /* Main entry point for Loop Versioning transformation.
1693 This transformation given a condition and a loop, creates
1694 -if (condition) { loop_copy1 } else { loop_copy2 },
1695 where loop_copy1 is the loop transformed in one way, and loop_copy2
1696 is the loop transformed in another way (or unchanged). 'condition'
1697 may be a run time test for things that were not resolved by static
1698 analysis (overlapping ranges (anti-aliasing), alignment, etc.).
1700 THEN_PROB is the probability of the then edge of the if. THEN_SCALE
1701 is the ratio by that the frequencies in the original loop should
1702 be scaled. ELSE_SCALE is the ratio by that the frequencies in the
1703 new loop should be scaled.
1705 If PLACE_AFTER is true, we place the new loop after LOOP in the
1706 instruction stream, otherwise it is placed before LOOP. */
1708 struct loop *
1709 loop_version (struct loop *loop,
1710 void *cond_expr, basic_block *condition_bb,
1711 unsigned then_prob, unsigned then_scale, unsigned else_scale,
1712 bool place_after)
1714 basic_block first_head, second_head;
1715 edge entry, latch_edge, true_edge, false_edge;
1716 int irred_flag;
1717 struct loop *nloop;
1718 basic_block cond_bb;
1720 /* Record entry and latch edges for the loop */
1721 entry = loop_preheader_edge (loop);
1722 irred_flag = entry->flags & EDGE_IRREDUCIBLE_LOOP;
1723 entry->flags &= ~EDGE_IRREDUCIBLE_LOOP;
1725 /* Note down head of loop as first_head. */
1726 first_head = entry->dest;
1728 /* Duplicate loop. */
1729 if (!cfg_hook_duplicate_loop_to_header_edge (loop, entry, 1,
1730 NULL, NULL, NULL, 0))
1732 entry->flags |= irred_flag;
1733 return NULL;
1736 /* After duplication entry edge now points to new loop head block.
1737 Note down new head as second_head. */
1738 second_head = entry->dest;
1740 /* Split loop entry edge and insert new block with cond expr. */
1741 cond_bb = lv_adjust_loop_entry_edge (first_head, second_head,
1742 entry, cond_expr, then_prob);
1743 if (condition_bb)
1744 *condition_bb = cond_bb;
1746 if (!cond_bb)
1748 entry->flags |= irred_flag;
1749 return NULL;
1752 latch_edge = single_succ_edge (get_bb_copy (loop->latch));
1754 extract_cond_bb_edges (cond_bb, &true_edge, &false_edge);
1755 nloop = loopify (latch_edge,
1756 single_pred_edge (get_bb_copy (loop->header)),
1757 cond_bb, true_edge, false_edge,
1758 false /* Do not redirect all edges. */,
1759 then_scale, else_scale);
1761 copy_loop_info (loop, nloop);
1763 /* loopify redirected latch_edge. Update its PENDING_STMTS. */
1764 lv_flush_pending_stmts (latch_edge);
1766 /* loopify redirected condition_bb's succ edge. Update its PENDING_STMTS. */
1767 extract_cond_bb_edges (cond_bb, &true_edge, &false_edge);
1768 lv_flush_pending_stmts (false_edge);
1769 /* Adjust irreducible flag. */
1770 if (irred_flag)
1772 cond_bb->flags |= BB_IRREDUCIBLE_LOOP;
1773 loop_preheader_edge (loop)->flags |= EDGE_IRREDUCIBLE_LOOP;
1774 loop_preheader_edge (nloop)->flags |= EDGE_IRREDUCIBLE_LOOP;
1775 single_pred_edge (cond_bb)->flags |= EDGE_IRREDUCIBLE_LOOP;
1778 if (place_after)
1780 basic_block *bbs = get_loop_body_in_dom_order (nloop), after;
1781 unsigned i;
1783 after = loop->latch;
1785 for (i = 0; i < nloop->num_nodes; i++)
1787 move_block_after (bbs[i], after);
1788 after = bbs[i];
1790 free (bbs);
1793 /* At this point condition_bb is loop preheader with two successors,
1794 first_head and second_head. Make sure that loop preheader has only
1795 one successor. */
1796 split_edge (loop_preheader_edge (loop));
1797 split_edge (loop_preheader_edge (nloop));
1799 return nloop;