1 /* Loop manipulation code for GNU compiler.
2 Copyright (C) 2002, 2003, 2004, 2005, 2007, 2008, 2009, 2010, 2011
3 Free Software Foundation, Inc.
5 This file is part of GCC.
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
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
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/>. */
23 #include "coretypes.h"
26 #include "hard-reg-set.h"
28 #include "basic-block.h"
30 #include "cfglayout.h"
33 #include "tree-flow.h"
35 static void copy_loops_to (struct loop **, int,
37 static void loop_redirect_edge (edge, basic_block);
38 static void remove_bbs (basic_block *, int);
39 static bool rpe_enum_p (const_basic_block, const void *);
40 static int find_path (edge, basic_block **);
41 static void fix_loop_placements (struct loop *, bool *);
42 static bool fix_bb_placement (basic_block);
43 static void fix_bb_placements (basic_block, bool *);
44 static void unloop (struct loop *, bool *);
46 #define RDIV(X,Y) (((X) + (Y) / 2) / (Y))
48 /* Checks whether basic block BB is dominated by DATA. */
50 rpe_enum_p (const_basic_block bb, const void *data)
52 return dominated_by_p (CDI_DOMINATORS, bb, (const_basic_block) data);
55 /* Remove basic blocks BBS. NBBS is the number of the basic blocks. */
58 remove_bbs (basic_block *bbs, int nbbs)
62 for (i = 0; i < nbbs; i++)
63 delete_basic_block (bbs[i]);
66 /* Find path -- i.e. the basic blocks dominated by edge E and put them
67 into array BBS, that will be allocated large enough to contain them.
68 E->dest must have exactly one predecessor for this to work (it is
69 easy to achieve and we do not put it here because we do not want to
70 alter anything by this function). The number of basic blocks in the
73 find_path (edge e, basic_block **bbs)
75 gcc_assert (EDGE_COUNT (e->dest->preds) <= 1);
77 /* Find bbs in the path. */
78 *bbs = XCNEWVEC (basic_block, n_basic_blocks);
79 return dfs_enumerate_from (e->dest, 0, rpe_enum_p, *bbs,
80 n_basic_blocks, e->dest);
83 /* Fix placement of basic block BB inside loop hierarchy --
84 Let L be a loop to that BB belongs. Then every successor of BB must either
85 1) belong to some superloop of loop L, or
86 2) be a header of loop K such that K->outer is superloop of L
87 Returns true if we had to move BB into other loop to enforce this condition,
88 false if the placement of BB was already correct (provided that placements
89 of its successors are correct). */
91 fix_bb_placement (basic_block bb)
95 struct loop *loop = current_loops->tree_root, *act;
97 FOR_EACH_EDGE (e, ei, bb->succs)
99 if (e->dest == EXIT_BLOCK_PTR)
102 act = e->dest->loop_father;
103 if (act->header == e->dest)
104 act = loop_outer (act);
106 if (flow_loop_nested_p (loop, act))
110 if (loop == bb->loop_father)
113 remove_bb_from_loops (bb);
114 add_bb_to_loop (bb, loop);
119 /* Fix placement of LOOP inside loop tree, i.e. find the innermost superloop
120 of LOOP to that leads at least one exit edge of LOOP, and set it
121 as the immediate superloop of LOOP. Return true if the immediate superloop
125 fix_loop_placement (struct loop *loop)
129 VEC (edge, heap) *exits = get_loop_exit_edges (loop);
130 struct loop *father = current_loops->tree_root, *act;
133 FOR_EACH_VEC_ELT (edge, exits, i, e)
135 act = find_common_loop (loop, e->dest->loop_father);
136 if (flow_loop_nested_p (father, act))
140 if (father != loop_outer (loop))
142 for (act = loop_outer (loop); act != father; act = loop_outer (act))
143 act->num_nodes -= loop->num_nodes;
144 flow_loop_tree_node_remove (loop);
145 flow_loop_tree_node_add (father, loop);
147 /* The exit edges of LOOP no longer exits its original immediate
148 superloops; remove them from the appropriate exit lists. */
149 FOR_EACH_VEC_ELT (edge, exits, i, e)
150 rescan_loop_exit (e, false, false);
155 VEC_free (edge, heap, exits);
159 /* Fix placements of basic blocks inside loop hierarchy stored in loops; i.e.
160 enforce condition condition stated in description of fix_bb_placement. We
161 start from basic block FROM that had some of its successors removed, so that
162 his placement no longer has to be correct, and iteratively fix placement of
163 its predecessors that may change if placement of FROM changed. Also fix
164 placement of subloops of FROM->loop_father, that might also be altered due
165 to this change; the condition for them is similar, except that instead of
166 successors we consider edges coming out of the loops.
168 If the changes may invalidate the information about irreducible regions,
169 IRRED_INVALIDATED is set to true. */
172 fix_bb_placements (basic_block from,
173 bool *irred_invalidated)
176 basic_block *queue, *qtop, *qbeg, *qend;
177 struct loop *base_loop, *target_loop;
180 /* We pass through blocks back-reachable from FROM, testing whether some
181 of their successors moved to outer loop. It may be necessary to
182 iterate several times, but it is finite, as we stop unless we move
183 the basic block up the loop structure. The whole story is a bit
184 more complicated due to presence of subloops, those are moved using
185 fix_loop_placement. */
187 base_loop = from->loop_father;
188 /* If we are already in the outermost loop, the basic blocks cannot be moved
189 outside of it. If FROM is the header of the base loop, it cannot be moved
190 outside of it, either. In both cases, we can end now. */
191 if (base_loop == current_loops->tree_root
192 || from == base_loop->header)
195 in_queue = sbitmap_alloc (last_basic_block);
196 sbitmap_zero (in_queue);
197 SET_BIT (in_queue, from->index);
198 /* Prevent us from going out of the base_loop. */
199 SET_BIT (in_queue, base_loop->header->index);
201 queue = XNEWVEC (basic_block, base_loop->num_nodes + 1);
202 qtop = queue + base_loop->num_nodes + 1;
214 RESET_BIT (in_queue, from->index);
216 if (from->loop_father->header == from)
218 /* Subloop header, maybe move the loop upward. */
219 if (!fix_loop_placement (from->loop_father))
221 target_loop = loop_outer (from->loop_father);
225 /* Ordinary basic block. */
226 if (!fix_bb_placement (from))
228 target_loop = from->loop_father;
231 FOR_EACH_EDGE (e, ei, from->succs)
233 if (e->flags & EDGE_IRREDUCIBLE_LOOP)
234 *irred_invalidated = true;
237 /* Something has changed, insert predecessors into queue. */
238 FOR_EACH_EDGE (e, ei, from->preds)
240 basic_block pred = e->src;
243 if (e->flags & EDGE_IRREDUCIBLE_LOOP)
244 *irred_invalidated = true;
246 if (TEST_BIT (in_queue, pred->index))
249 /* If it is subloop, then it either was not moved, or
250 the path up the loop tree from base_loop do not contain
252 nca = find_common_loop (pred->loop_father, base_loop);
253 if (pred->loop_father != base_loop
255 || nca != pred->loop_father))
256 pred = pred->loop_father->header;
257 else if (!flow_loop_nested_p (target_loop, pred->loop_father))
259 /* If PRED is already higher in the loop hierarchy than the
260 TARGET_LOOP to that we moved FROM, the change of the position
261 of FROM does not affect the position of PRED, so there is no
262 point in processing it. */
266 if (TEST_BIT (in_queue, pred->index))
269 /* Schedule the basic block. */
274 SET_BIT (in_queue, pred->index);
281 /* Removes path beginning at edge E, i.e. remove basic blocks dominated by E
282 and update loop structures and dominators. Return true if we were able
283 to remove the path, false otherwise (and nothing is affected then). */
288 basic_block *rem_bbs, *bord_bbs, from, bb;
289 VEC (basic_block, heap) *dom_bbs;
290 int i, nrem, n_bord_bbs;
292 bool irred_invalidated = false;
295 if (!can_remove_branch_p (e))
298 /* Keep track of whether we need to update information about irreducible
299 regions. This is the case if the removed area is a part of the
300 irreducible region, or if the set of basic blocks that belong to a loop
301 that is inside an irreducible region is changed, or if such a loop is
303 if (e->flags & EDGE_IRREDUCIBLE_LOOP)
304 irred_invalidated = true;
306 /* We need to check whether basic blocks are dominated by the edge
307 e, but we only have basic block dominators. This is easy to
308 fix -- when e->dest has exactly one predecessor, this corresponds
309 to blocks dominated by e->dest, if not, split the edge. */
310 if (!single_pred_p (e->dest))
311 e = single_pred_edge (split_edge (e));
313 /* It may happen that by removing path we remove one or more loops
314 we belong to. In this case first unloop the loops, then proceed
315 normally. We may assume that e->dest is not a header of any loop,
316 as it now has exactly one predecessor. */
317 while (loop_outer (e->src->loop_father)
318 && dominated_by_p (CDI_DOMINATORS,
319 e->src->loop_father->latch, e->dest))
320 unloop (e->src->loop_father, &irred_invalidated);
322 /* Identify the path. */
323 nrem = find_path (e, &rem_bbs);
326 bord_bbs = XCNEWVEC (basic_block, n_basic_blocks);
327 seen = sbitmap_alloc (last_basic_block);
330 /* Find "border" hexes -- i.e. those with predecessor in removed path. */
331 for (i = 0; i < nrem; i++)
332 SET_BIT (seen, rem_bbs[i]->index);
333 if (!irred_invalidated)
334 FOR_EACH_EDGE (ae, ei, e->src->succs)
335 if (ae != e && ae->dest != EXIT_BLOCK_PTR && !TEST_BIT (seen, ae->dest->index)
336 && ae->flags & EDGE_IRREDUCIBLE_LOOP)
337 irred_invalidated = true;
338 for (i = 0; i < nrem; i++)
341 FOR_EACH_EDGE (ae, ei, rem_bbs[i]->succs)
342 if (ae->dest != EXIT_BLOCK_PTR && !TEST_BIT (seen, ae->dest->index))
344 SET_BIT (seen, ae->dest->index);
345 bord_bbs[n_bord_bbs++] = ae->dest;
347 if (ae->flags & EDGE_IRREDUCIBLE_LOOP)
348 irred_invalidated = true;
352 /* Remove the path. */
357 /* Cancel loops contained in the path. */
358 for (i = 0; i < nrem; i++)
359 if (rem_bbs[i]->loop_father->header == rem_bbs[i])
360 cancel_loop_tree (rem_bbs[i]->loop_father);
362 remove_bbs (rem_bbs, nrem);
365 /* Find blocks whose dominators may be affected. */
367 for (i = 0; i < n_bord_bbs; i++)
371 bb = get_immediate_dominator (CDI_DOMINATORS, bord_bbs[i]);
372 if (TEST_BIT (seen, bb->index))
374 SET_BIT (seen, bb->index);
376 for (ldom = first_dom_son (CDI_DOMINATORS, bb);
378 ldom = next_dom_son (CDI_DOMINATORS, ldom))
379 if (!dominated_by_p (CDI_DOMINATORS, from, ldom))
380 VEC_safe_push (basic_block, heap, dom_bbs, ldom);
385 /* Recount dominators. */
386 iterate_fix_dominators (CDI_DOMINATORS, dom_bbs, true);
387 VEC_free (basic_block, heap, dom_bbs);
390 /* Fix placements of basic blocks inside loops and the placement of
391 loops in the loop tree. */
392 fix_bb_placements (from, &irred_invalidated);
393 fix_loop_placements (from->loop_father, &irred_invalidated);
395 if (irred_invalidated
396 && loops_state_satisfies_p (LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS))
397 mark_irreducible_loops ();
402 /* Creates place for a new LOOP in loops structure. */
405 place_new_loop (struct loop *loop)
407 loop->num = number_of_loops ();
408 VEC_safe_push (loop_p, gc, current_loops->larray, loop);
411 /* Given LOOP structure with filled header and latch, find the body of the
412 corresponding loop and add it to loops tree. Insert the LOOP as a son of
416 add_loop (struct loop *loop, struct loop *outer)
420 struct loop *subloop;
424 /* Add it to loop structure. */
425 place_new_loop (loop);
426 flow_loop_tree_node_add (outer, loop);
428 /* Find its nodes. */
429 bbs = XNEWVEC (basic_block, n_basic_blocks);
430 n = get_loop_body_with_size (loop, bbs, n_basic_blocks);
432 for (i = 0; i < n; i++)
434 if (bbs[i]->loop_father == outer)
436 remove_bb_from_loops (bbs[i]);
437 add_bb_to_loop (bbs[i], loop);
443 /* If we find a direct subloop of OUTER, move it to LOOP. */
444 subloop = bbs[i]->loop_father;
445 if (loop_outer (subloop) == outer
446 && subloop->header == bbs[i])
448 flow_loop_tree_node_remove (subloop);
449 flow_loop_tree_node_add (loop, subloop);
453 /* Update the information about loop exit edges. */
454 for (i = 0; i < n; i++)
456 FOR_EACH_EDGE (e, ei, bbs[i]->succs)
458 rescan_loop_exit (e, false, false);
465 /* Multiply all frequencies in LOOP by NUM/DEN. */
467 scale_loop_frequencies (struct loop *loop, int num, int den)
471 bbs = get_loop_body (loop);
472 scale_bbs_frequencies_int (bbs, loop->num_nodes, num, den);
476 /* Recompute dominance information for basic blocks outside LOOP. */
479 update_dominators_in_loop (struct loop *loop)
481 VEC (basic_block, heap) *dom_bbs = NULL;
486 seen = sbitmap_alloc (last_basic_block);
488 body = get_loop_body (loop);
490 for (i = 0; i < loop->num_nodes; i++)
491 SET_BIT (seen, body[i]->index);
493 for (i = 0; i < loop->num_nodes; i++)
497 for (ldom = first_dom_son (CDI_DOMINATORS, body[i]);
499 ldom = next_dom_son (CDI_DOMINATORS, ldom))
500 if (!TEST_BIT (seen, ldom->index))
502 SET_BIT (seen, ldom->index);
503 VEC_safe_push (basic_block, heap, dom_bbs, ldom);
507 iterate_fix_dominators (CDI_DOMINATORS, dom_bbs, false);
510 VEC_free (basic_block, heap, dom_bbs);
513 /* Creates an if region as shown above. CONDITION is used to create
517 | ------------- -------------
518 | | pred_bb | | pred_bb |
519 | ------------- -------------
523 | | ====> -------------
528 | ------------- e_false / \ e_true
530 | ------------- ----------- -----------
531 | | false_bb | | true_bb |
532 | ----------- -----------
539 | | exit_edge (result)
548 create_empty_if_region_on_edge (edge entry_edge, tree condition)
551 basic_block cond_bb, true_bb, false_bb, join_bb;
552 edge e_true, e_false, exit_edge;
555 gimple_stmt_iterator gsi;
557 cond_bb = split_edge (entry_edge);
559 /* Insert condition in cond_bb. */
560 gsi = gsi_last_bb (cond_bb);
562 force_gimple_operand_gsi (&gsi, condition, true, NULL,
563 false, GSI_NEW_STMT);
564 cond_stmt = gimple_build_cond_from_tree (simple_cond, NULL_TREE, NULL_TREE);
565 gsi = gsi_last_bb (cond_bb);
566 gsi_insert_after (&gsi, cond_stmt, GSI_NEW_STMT);
568 join_bb = split_edge (single_succ_edge (cond_bb));
570 e_true = single_succ_edge (cond_bb);
571 true_bb = split_edge (e_true);
573 e_false = make_edge (cond_bb, join_bb, 0);
574 false_bb = split_edge (e_false);
576 e_true->flags &= ~EDGE_FALLTHRU;
577 e_true->flags |= EDGE_TRUE_VALUE;
578 e_false->flags &= ~EDGE_FALLTHRU;
579 e_false->flags |= EDGE_FALSE_VALUE;
581 set_immediate_dominator (CDI_DOMINATORS, cond_bb, entry_edge->src);
582 set_immediate_dominator (CDI_DOMINATORS, true_bb, cond_bb);
583 set_immediate_dominator (CDI_DOMINATORS, false_bb, cond_bb);
584 set_immediate_dominator (CDI_DOMINATORS, join_bb, cond_bb);
586 exit_edge = single_succ_edge (join_bb);
588 if (single_pred_p (exit_edge->dest))
589 set_immediate_dominator (CDI_DOMINATORS, exit_edge->dest, join_bb);
594 /* create_empty_loop_on_edge
596 | - pred_bb - ------ pred_bb ------
597 | | | | iv0 = initial_value |
598 | -----|----- ---------|-----------
599 | | ______ | entry_edge
601 | | ====> | -V---V- loop_header -------------
602 | V | | iv_before = phi (iv0, iv_after) |
603 | - succ_bb - | ---|-----------------------------
605 | ----------- | ---V--- loop_body ---------------
606 | | | iv_after = iv_before + stride |
607 | | | if (iv_before < upper_bound) |
608 | | ---|--------------\--------------
611 | | - loop_latch - V- succ_bb -
613 | | /------------- -----------
616 Creates an empty loop as shown above, the IV_BEFORE is the SSA_NAME
617 that is used before the increment of IV. IV_BEFORE should be used for
618 adding code to the body that uses the IV. OUTER is the outer loop in
619 which the new loop should be inserted.
621 Both INITIAL_VALUE and UPPER_BOUND expressions are gimplified and
622 inserted on the loop entry edge. This implies that this function
623 should be used only when the UPPER_BOUND expression is a loop
627 create_empty_loop_on_edge (edge entry_edge,
629 tree stride, tree upper_bound,
635 basic_block loop_header, loop_latch, succ_bb, pred_bb;
637 gimple_stmt_iterator gsi;
644 gcc_assert (entry_edge && initial_value && stride && upper_bound && iv);
646 /* Create header, latch and wire up the loop. */
647 pred_bb = entry_edge->src;
648 loop_header = split_edge (entry_edge);
649 loop_latch = split_edge (single_succ_edge (loop_header));
650 succ_bb = single_succ (loop_latch);
651 make_edge (loop_header, succ_bb, 0);
652 redirect_edge_succ_nodup (single_succ_edge (loop_latch), loop_header);
654 /* Set immediate dominator information. */
655 set_immediate_dominator (CDI_DOMINATORS, loop_header, pred_bb);
656 set_immediate_dominator (CDI_DOMINATORS, loop_latch, loop_header);
657 set_immediate_dominator (CDI_DOMINATORS, succ_bb, loop_header);
659 /* Initialize a loop structure and put it in a loop hierarchy. */
660 loop = alloc_loop ();
661 loop->header = loop_header;
662 loop->latch = loop_latch;
663 add_loop (loop, outer);
665 /* TODO: Fix frequencies and counts. */
666 prob = REG_BR_PROB_BASE / 2;
668 scale_loop_frequencies (loop, REG_BR_PROB_BASE - prob, REG_BR_PROB_BASE);
670 /* Update dominators. */
671 update_dominators_in_loop (loop);
673 /* Modify edge flags. */
674 exit_e = single_exit (loop);
675 exit_e->flags = EDGE_LOOP_EXIT | EDGE_FALSE_VALUE;
676 single_pred_edge (loop_latch)->flags = EDGE_TRUE_VALUE;
678 /* Construct IV code in loop. */
679 initial_value = force_gimple_operand (initial_value, &stmts, true, iv);
682 gsi_insert_seq_on_edge (loop_preheader_edge (loop), stmts);
683 gsi_commit_edge_inserts ();
686 upper_bound = force_gimple_operand (upper_bound, &stmts, true, NULL);
689 gsi_insert_seq_on_edge (loop_preheader_edge (loop), stmts);
690 gsi_commit_edge_inserts ();
693 gsi = gsi_last_bb (loop_header);
694 create_iv (initial_value, stride, iv, loop, &gsi, false,
695 iv_before, iv_after);
697 /* Insert loop exit condition. */
698 cond_expr = gimple_build_cond
699 (LT_EXPR, *iv_before, upper_bound, NULL_TREE, NULL_TREE);
701 exit_test = gimple_cond_lhs (cond_expr);
702 exit_test = force_gimple_operand_gsi (&gsi, exit_test, true, NULL,
703 false, GSI_NEW_STMT);
704 gimple_cond_set_lhs (cond_expr, exit_test);
705 gsi = gsi_last_bb (exit_e->src);
706 gsi_insert_after (&gsi, cond_expr, GSI_NEW_STMT);
708 split_block_after_labels (loop_header);
713 /* Make area between HEADER_EDGE and LATCH_EDGE a loop by connecting
714 latch to header and update loop tree and dominators
715 accordingly. Everything between them plus LATCH_EDGE destination must
716 be dominated by HEADER_EDGE destination, and back-reachable from
717 LATCH_EDGE source. HEADER_EDGE is redirected to basic block SWITCH_BB,
718 FALSE_EDGE of SWITCH_BB to original destination of HEADER_EDGE and
719 TRUE_EDGE of SWITCH_BB to original destination of LATCH_EDGE.
720 Returns the newly created loop. Frequencies and counts in the new loop
721 are scaled by FALSE_SCALE and in the old one by TRUE_SCALE. */
724 loopify (edge latch_edge, edge header_edge,
725 basic_block switch_bb, edge true_edge, edge false_edge,
726 bool redirect_all_edges, unsigned true_scale, unsigned false_scale)
728 basic_block succ_bb = latch_edge->dest;
729 basic_block pred_bb = header_edge->src;
730 struct loop *loop = alloc_loop ();
731 struct loop *outer = loop_outer (succ_bb->loop_father);
737 loop->header = header_edge->dest;
738 loop->latch = latch_edge->src;
740 freq = EDGE_FREQUENCY (header_edge);
741 cnt = header_edge->count;
743 /* Redirect edges. */
744 loop_redirect_edge (latch_edge, loop->header);
745 loop_redirect_edge (true_edge, succ_bb);
747 /* During loop versioning, one of the switch_bb edge is already properly
748 set. Do not redirect it again unless redirect_all_edges is true. */
749 if (redirect_all_edges)
751 loop_redirect_edge (header_edge, switch_bb);
752 loop_redirect_edge (false_edge, loop->header);
754 /* Update dominators. */
755 set_immediate_dominator (CDI_DOMINATORS, switch_bb, pred_bb);
756 set_immediate_dominator (CDI_DOMINATORS, loop->header, switch_bb);
759 set_immediate_dominator (CDI_DOMINATORS, succ_bb, switch_bb);
761 /* Compute new loop. */
762 add_loop (loop, outer);
764 /* Add switch_bb to appropriate loop. */
765 if (switch_bb->loop_father)
766 remove_bb_from_loops (switch_bb);
767 add_bb_to_loop (switch_bb, outer);
769 /* Fix frequencies. */
770 if (redirect_all_edges)
772 switch_bb->frequency = freq;
773 switch_bb->count = cnt;
774 FOR_EACH_EDGE (e, ei, switch_bb->succs)
776 e->count = (switch_bb->count * e->probability) / REG_BR_PROB_BASE;
779 scale_loop_frequencies (loop, false_scale, REG_BR_PROB_BASE);
780 scale_loop_frequencies (succ_bb->loop_father, true_scale, REG_BR_PROB_BASE);
781 update_dominators_in_loop (loop);
786 /* Remove the latch edge of a LOOP and update loops to indicate that
787 the LOOP was removed. After this function, original loop latch will
788 have no successor, which caller is expected to fix somehow.
790 If this may cause the information about irreducible regions to become
791 invalid, IRRED_INVALIDATED is set to true. */
794 unloop (struct loop *loop, bool *irred_invalidated)
799 basic_block latch = loop->latch;
802 if (loop_preheader_edge (loop)->flags & EDGE_IRREDUCIBLE_LOOP)
803 *irred_invalidated = true;
805 /* This is relatively straightforward. The dominators are unchanged, as
806 loop header dominates loop latch, so the only thing we have to care of
807 is the placement of loops and basic blocks inside the loop tree. We
808 move them all to the loop->outer, and then let fix_bb_placements do
811 body = get_loop_body (loop);
813 for (i = 0; i < n; i++)
814 if (body[i]->loop_father == loop)
816 remove_bb_from_loops (body[i]);
817 add_bb_to_loop (body[i], loop_outer (loop));
824 flow_loop_tree_node_remove (ploop);
825 flow_loop_tree_node_add (loop_outer (loop), ploop);
828 /* Remove the loop and free its data. */
831 remove_edge (single_succ_edge (latch));
833 /* We do not pass IRRED_INVALIDATED to fix_bb_placements here, as even if
834 there is an irreducible region inside the cancelled loop, the flags will
836 fix_bb_placements (latch, &dummy);
839 /* Fix placement of superloops of LOOP inside loop tree, i.e. ensure that
840 condition stated in description of fix_loop_placement holds for them.
841 It is used in case when we removed some edges coming out of LOOP, which
842 may cause the right placement of LOOP inside loop tree to change.
844 IRRED_INVALIDATED is set to true if a change in the loop structures might
845 invalidate the information about irreducible regions. */
848 fix_loop_placements (struct loop *loop, bool *irred_invalidated)
852 while (loop_outer (loop))
854 outer = loop_outer (loop);
855 if (!fix_loop_placement (loop))
858 /* Changing the placement of a loop in the loop tree may alter the
859 validity of condition 2) of the description of fix_bb_placement
860 for its preheader, because the successor is the header and belongs
861 to the loop. So call fix_bb_placements to fix up the placement
862 of the preheader and (possibly) of its predecessors. */
863 fix_bb_placements (loop_preheader_edge (loop)->src,
869 /* Copies copy of LOOP as subloop of TARGET loop, placing newly
870 created loop into loops structure. */
872 duplicate_loop (struct loop *loop, struct loop *target)
875 cloop = alloc_loop ();
876 place_new_loop (cloop);
878 /* Mark the new loop as copy of LOOP. */
879 set_loop_copy (loop, cloop);
881 /* Add it to target. */
882 flow_loop_tree_node_add (target, cloop);
887 /* Copies structure of subloops of LOOP into TARGET loop, placing
888 newly created loops into loop tree. */
890 duplicate_subloops (struct loop *loop, struct loop *target)
892 struct loop *aloop, *cloop;
894 for (aloop = loop->inner; aloop; aloop = aloop->next)
896 cloop = duplicate_loop (aloop, target);
897 duplicate_subloops (aloop, cloop);
901 /* Copies structure of subloops of N loops, stored in array COPIED_LOOPS,
902 into TARGET loop, placing newly created loops into loop tree. */
904 copy_loops_to (struct loop **copied_loops, int n, struct loop *target)
909 for (i = 0; i < n; i++)
911 aloop = duplicate_loop (copied_loops[i], target);
912 duplicate_subloops (copied_loops[i], aloop);
916 /* Redirects edge E to basic block DEST. */
918 loop_redirect_edge (edge e, basic_block dest)
923 redirect_edge_and_branch_force (e, dest);
926 /* Check whether LOOP's body can be duplicated. */
928 can_duplicate_loop_p (const struct loop *loop)
931 basic_block *bbs = get_loop_body (loop);
933 ret = can_copy_bbs_p (bbs, loop->num_nodes);
939 /* Sets probability and count of edge E to zero. The probability and count
940 is redistributed evenly to the remaining edges coming from E->src. */
943 set_zero_probability (edge e)
945 basic_block bb = e->src;
947 edge ae, last = NULL;
948 unsigned n = EDGE_COUNT (bb->succs);
949 gcov_type cnt = e->count, cnt1;
950 unsigned prob = e->probability, prob1;
953 cnt1 = cnt / (n - 1);
954 prob1 = prob / (n - 1);
956 FOR_EACH_EDGE (ae, ei, bb->succs)
961 ae->probability += prob1;
966 /* Move the rest to one of the edges. */
967 last->probability += prob % (n - 1);
968 last->count += cnt % (n - 1);
974 /* Duplicates body of LOOP to given edge E NDUPL times. Takes care of updating
975 loop structure and dominators. E's destination must be LOOP header for
976 this to work, i.e. it must be entry or latch edge of this loop; these are
977 unique, as the loops must have preheaders for this function to work
978 correctly (in case E is latch, the function unrolls the loop, if E is entry
979 edge, it peels the loop). Store edges created by copying ORIG edge from
980 copies corresponding to set bits in WONT_EXIT bitmap (bit 0 corresponds to
981 original LOOP body, the other copies are numbered in order given by control
982 flow through them) into TO_REMOVE array. Returns false if duplication is
986 duplicate_loop_to_header_edge (struct loop *loop, edge e,
987 unsigned int ndupl, sbitmap wont_exit,
988 edge orig, VEC (edge, heap) **to_remove,
991 struct loop *target, *aloop;
992 struct loop **orig_loops;
993 unsigned n_orig_loops;
994 basic_block header = loop->header, latch = loop->latch;
995 basic_block *new_bbs, *bbs, *first_active;
996 basic_block new_bb, bb, first_active_latch = NULL;
998 edge spec_edges[2], new_spec_edges[2];
1002 int is_latch = (latch == e->src);
1003 int scale_act = 0, *scale_step = NULL, scale_main = 0;
1004 int scale_after_exit = 0;
1005 int p, freq_in, freq_le, freq_out_orig;
1006 int prob_pass_thru, prob_pass_wont_exit, prob_pass_main;
1007 int add_irreducible_flag;
1008 basic_block place_after;
1009 bitmap bbs_to_scale = NULL;
1012 gcc_assert (e->dest == loop->header);
1013 gcc_assert (ndupl > 0);
1017 /* Orig must be edge out of the loop. */
1018 gcc_assert (flow_bb_inside_loop_p (loop, orig->src));
1019 gcc_assert (!flow_bb_inside_loop_p (loop, orig->dest));
1022 n = loop->num_nodes;
1023 bbs = get_loop_body_in_dom_order (loop);
1024 gcc_assert (bbs[0] == loop->header);
1025 gcc_assert (bbs[n - 1] == loop->latch);
1027 /* Check whether duplication is possible. */
1028 if (!can_copy_bbs_p (bbs, loop->num_nodes))
1033 new_bbs = XNEWVEC (basic_block, loop->num_nodes);
1035 /* In case we are doing loop peeling and the loop is in the middle of
1036 irreducible region, the peeled copies will be inside it too. */
1037 add_irreducible_flag = e->flags & EDGE_IRREDUCIBLE_LOOP;
1038 gcc_assert (!is_latch || !add_irreducible_flag);
1040 /* Find edge from latch. */
1041 latch_edge = loop_latch_edge (loop);
1043 if (flags & DLTHE_FLAG_UPDATE_FREQ)
1045 /* Calculate coefficients by that we have to scale frequencies
1046 of duplicated loop bodies. */
1047 freq_in = header->frequency;
1048 freq_le = EDGE_FREQUENCY (latch_edge);
1051 if (freq_in < freq_le)
1053 freq_out_orig = orig ? EDGE_FREQUENCY (orig) : freq_in - freq_le;
1054 if (freq_out_orig > freq_in - freq_le)
1055 freq_out_orig = freq_in - freq_le;
1056 prob_pass_thru = RDIV (REG_BR_PROB_BASE * freq_le, freq_in);
1057 prob_pass_wont_exit =
1058 RDIV (REG_BR_PROB_BASE * (freq_le + freq_out_orig), freq_in);
1061 && REG_BR_PROB_BASE - orig->probability != 0)
1063 /* The blocks that are dominated by a removed exit edge ORIG have
1064 frequencies scaled by this. */
1065 scale_after_exit = RDIV (REG_BR_PROB_BASE * REG_BR_PROB_BASE,
1066 REG_BR_PROB_BASE - orig->probability);
1067 bbs_to_scale = BITMAP_ALLOC (NULL);
1068 for (i = 0; i < n; i++)
1070 if (bbs[i] != orig->src
1071 && dominated_by_p (CDI_DOMINATORS, bbs[i], orig->src))
1072 bitmap_set_bit (bbs_to_scale, i);
1076 scale_step = XNEWVEC (int, ndupl);
1078 for (i = 1; i <= ndupl; i++)
1079 scale_step[i - 1] = TEST_BIT (wont_exit, i)
1080 ? prob_pass_wont_exit
1083 /* Complete peeling is special as the probability of exit in last
1085 if (flags & DLTHE_FLAG_COMPLETTE_PEEL)
1087 int wanted_freq = EDGE_FREQUENCY (e);
1089 if (wanted_freq > freq_in)
1090 wanted_freq = freq_in;
1092 gcc_assert (!is_latch);
1093 /* First copy has frequency of incoming edge. Each subsequent
1094 frequency should be reduced by prob_pass_wont_exit. Caller
1095 should've managed the flags so all except for original loop
1096 has won't exist set. */
1097 scale_act = RDIV (wanted_freq * REG_BR_PROB_BASE, freq_in);
1098 /* Now simulate the duplication adjustments and compute header
1099 frequency of the last copy. */
1100 for (i = 0; i < ndupl; i++)
1101 wanted_freq = RDIV (wanted_freq * scale_step[i], REG_BR_PROB_BASE);
1102 scale_main = RDIV (wanted_freq * REG_BR_PROB_BASE, freq_in);
1106 prob_pass_main = TEST_BIT (wont_exit, 0)
1107 ? prob_pass_wont_exit
1110 scale_main = REG_BR_PROB_BASE;
1111 for (i = 0; i < ndupl; i++)
1114 p = RDIV (p * scale_step[i], REG_BR_PROB_BASE);
1116 scale_main = RDIV (REG_BR_PROB_BASE * REG_BR_PROB_BASE, scale_main);
1117 scale_act = RDIV (scale_main * prob_pass_main, REG_BR_PROB_BASE);
1121 scale_main = REG_BR_PROB_BASE;
1122 for (i = 0; i < ndupl; i++)
1123 scale_main = RDIV (scale_main * scale_step[i], REG_BR_PROB_BASE);
1124 scale_act = REG_BR_PROB_BASE - prob_pass_thru;
1126 for (i = 0; i < ndupl; i++)
1127 gcc_assert (scale_step[i] >= 0 && scale_step[i] <= REG_BR_PROB_BASE);
1128 gcc_assert (scale_main >= 0 && scale_main <= REG_BR_PROB_BASE
1129 && scale_act >= 0 && scale_act <= REG_BR_PROB_BASE);
1132 /* Loop the new bbs will belong to. */
1133 target = e->src->loop_father;
1135 /* Original loops. */
1137 for (aloop = loop->inner; aloop; aloop = aloop->next)
1139 orig_loops = XCNEWVEC (struct loop *, n_orig_loops);
1140 for (aloop = loop->inner, i = 0; aloop; aloop = aloop->next, i++)
1141 orig_loops[i] = aloop;
1143 set_loop_copy (loop, target);
1145 first_active = XNEWVEC (basic_block, n);
1148 memcpy (first_active, bbs, n * sizeof (basic_block));
1149 first_active_latch = latch;
1152 spec_edges[SE_ORIG] = orig;
1153 spec_edges[SE_LATCH] = latch_edge;
1155 place_after = e->src;
1156 for (j = 0; j < ndupl; j++)
1159 copy_loops_to (orig_loops, n_orig_loops, target);
1162 copy_bbs (bbs, n, new_bbs, spec_edges, 2, new_spec_edges, loop,
1164 place_after = new_spec_edges[SE_LATCH]->src;
1166 if (flags & DLTHE_RECORD_COPY_NUMBER)
1167 for (i = 0; i < n; i++)
1169 gcc_assert (!new_bbs[i]->aux);
1170 new_bbs[i]->aux = (void *)(size_t)(j + 1);
1173 /* Note whether the blocks and edges belong to an irreducible loop. */
1174 if (add_irreducible_flag)
1176 for (i = 0; i < n; i++)
1177 new_bbs[i]->flags |= BB_DUPLICATED;
1178 for (i = 0; i < n; i++)
1181 new_bb = new_bbs[i];
1182 if (new_bb->loop_father == target)
1183 new_bb->flags |= BB_IRREDUCIBLE_LOOP;
1185 FOR_EACH_EDGE (ae, ei, new_bb->succs)
1186 if ((ae->dest->flags & BB_DUPLICATED)
1187 && (ae->src->loop_father == target
1188 || ae->dest->loop_father == target))
1189 ae->flags |= EDGE_IRREDUCIBLE_LOOP;
1191 for (i = 0; i < n; i++)
1192 new_bbs[i]->flags &= ~BB_DUPLICATED;
1195 /* Redirect the special edges. */
1198 redirect_edge_and_branch_force (latch_edge, new_bbs[0]);
1199 redirect_edge_and_branch_force (new_spec_edges[SE_LATCH],
1201 set_immediate_dominator (CDI_DOMINATORS, new_bbs[0], latch);
1202 latch = loop->latch = new_bbs[n - 1];
1203 e = latch_edge = new_spec_edges[SE_LATCH];
1207 redirect_edge_and_branch_force (new_spec_edges[SE_LATCH],
1209 redirect_edge_and_branch_force (e, new_bbs[0]);
1210 set_immediate_dominator (CDI_DOMINATORS, new_bbs[0], e->src);
1211 e = new_spec_edges[SE_LATCH];
1214 /* Record exit edge in this copy. */
1215 if (orig && TEST_BIT (wont_exit, j + 1))
1218 VEC_safe_push (edge, heap, *to_remove, new_spec_edges[SE_ORIG]);
1219 set_zero_probability (new_spec_edges[SE_ORIG]);
1221 /* Scale the frequencies of the blocks dominated by the exit. */
1224 EXECUTE_IF_SET_IN_BITMAP (bbs_to_scale, 0, i, bi)
1226 scale_bbs_frequencies_int (new_bbs + i, 1, scale_after_exit,
1232 /* Record the first copy in the control flow order if it is not
1233 the original loop (i.e. in case of peeling). */
1234 if (!first_active_latch)
1236 memcpy (first_active, new_bbs, n * sizeof (basic_block));
1237 first_active_latch = new_bbs[n - 1];
1240 /* Set counts and frequencies. */
1241 if (flags & DLTHE_FLAG_UPDATE_FREQ)
1243 scale_bbs_frequencies_int (new_bbs, n, scale_act, REG_BR_PROB_BASE);
1244 scale_act = RDIV (scale_act * scale_step[j], REG_BR_PROB_BASE);
1250 /* Record the exit edge in the original loop body, and update the frequencies. */
1251 if (orig && TEST_BIT (wont_exit, 0))
1254 VEC_safe_push (edge, heap, *to_remove, orig);
1255 set_zero_probability (orig);
1257 /* Scale the frequencies of the blocks dominated by the exit. */
1260 EXECUTE_IF_SET_IN_BITMAP (bbs_to_scale, 0, i, bi)
1262 scale_bbs_frequencies_int (bbs + i, 1, scale_after_exit,
1268 /* Update the original loop. */
1270 set_immediate_dominator (CDI_DOMINATORS, e->dest, e->src);
1271 if (flags & DLTHE_FLAG_UPDATE_FREQ)
1273 scale_bbs_frequencies_int (bbs, n, scale_main, REG_BR_PROB_BASE);
1277 /* Update dominators of outer blocks if affected. */
1278 for (i = 0; i < n; i++)
1280 basic_block dominated, dom_bb;
1281 VEC (basic_block, heap) *dom_bbs;
1287 dom_bbs = get_dominated_by (CDI_DOMINATORS, bb);
1288 FOR_EACH_VEC_ELT (basic_block, dom_bbs, j, dominated)
1290 if (flow_bb_inside_loop_p (loop, dominated))
1292 dom_bb = nearest_common_dominator (
1293 CDI_DOMINATORS, first_active[i], first_active_latch);
1294 set_immediate_dominator (CDI_DOMINATORS, dominated, dom_bb);
1296 VEC_free (basic_block, heap, dom_bbs);
1298 free (first_active);
1301 BITMAP_FREE (bbs_to_scale);
1306 /* A callback for make_forwarder block, to redirect all edges except for
1307 MFB_KJ_EDGE to the entry part. E is the edge for that we should decide
1308 whether to redirect it. */
1312 mfb_keep_just (edge e)
1314 return e != mfb_kj_edge;
1317 /* True when a candidate preheader BLOCK has predecessors from LOOP. */
1320 has_preds_from_loop (basic_block block, struct loop *loop)
1325 FOR_EACH_EDGE (e, ei, block->preds)
1326 if (e->src->loop_father == loop)
1331 /* Creates a pre-header for a LOOP. Returns newly created block. Unless
1332 CP_SIMPLE_PREHEADERS is set in FLAGS, we only force LOOP to have single
1333 entry; otherwise we also force preheader block to have only one successor.
1334 When CP_FALLTHRU_PREHEADERS is set in FLAGS, we force the preheader block
1335 to be a fallthru predecessor to the loop header and to have only
1336 predecessors from outside of the loop.
1337 The function also updates dominators. */
1340 create_preheader (struct loop *loop, int flags)
1346 bool latch_edge_was_fallthru;
1347 edge one_succ_pred = NULL, single_entry = NULL;
1350 FOR_EACH_EDGE (e, ei, loop->header->preds)
1352 if (e->src == loop->latch)
1354 irred |= (e->flags & EDGE_IRREDUCIBLE_LOOP) != 0;
1357 if (single_succ_p (e->src))
1360 gcc_assert (nentry);
1363 bool need_forwarder_block = false;
1365 /* We do not allow entry block to be the loop preheader, since we
1366 cannot emit code there. */
1367 if (single_entry->src == ENTRY_BLOCK_PTR)
1368 need_forwarder_block = true;
1371 /* If we want simple preheaders, also force the preheader to have
1372 just a single successor. */
1373 if ((flags & CP_SIMPLE_PREHEADERS)
1374 && !single_succ_p (single_entry->src))
1375 need_forwarder_block = true;
1376 /* If we want fallthru preheaders, also create forwarder block when
1377 preheader ends with a jump or has predecessors from loop. */
1378 else if ((flags & CP_FALLTHRU_PREHEADERS)
1379 && (JUMP_P (BB_END (single_entry->src))
1380 || has_preds_from_loop (single_entry->src, loop)))
1381 need_forwarder_block = true;
1383 if (! need_forwarder_block)
1387 mfb_kj_edge = loop_latch_edge (loop);
1388 latch_edge_was_fallthru = (mfb_kj_edge->flags & EDGE_FALLTHRU) != 0;
1389 fallthru = make_forwarder_block (loop->header, mfb_keep_just, NULL);
1390 dummy = fallthru->src;
1391 loop->header = fallthru->dest;
1393 /* Try to be clever in placing the newly created preheader. The idea is to
1394 avoid breaking any "fallthruness" relationship between blocks.
1396 The preheader was created just before the header and all incoming edges
1397 to the header were redirected to the preheader, except the latch edge.
1398 So the only problematic case is when this latch edge was a fallthru
1399 edge: it is not anymore after the preheader creation so we have broken
1400 the fallthruness. We're therefore going to look for a better place. */
1401 if (latch_edge_was_fallthru)
1406 e = EDGE_PRED (dummy, 0);
1408 move_block_after (dummy, e->src);
1413 dummy->flags |= BB_IRREDUCIBLE_LOOP;
1414 single_succ_edge (dummy)->flags |= EDGE_IRREDUCIBLE_LOOP;
1418 fprintf (dump_file, "Created preheader block for loop %i\n",
1421 if (flags & CP_FALLTHRU_PREHEADERS)
1422 gcc_assert ((single_succ_edge (dummy)->flags & EDGE_FALLTHRU)
1423 && !JUMP_P (BB_END (dummy)));
1428 /* Create preheaders for each loop; for meaning of FLAGS see create_preheader. */
1431 create_preheaders (int flags)
1439 FOR_EACH_LOOP (li, loop, 0)
1440 create_preheader (loop, flags);
1441 loops_state_set (LOOPS_HAVE_PREHEADERS);
1444 /* Forces all loop latches to have only single successor. */
1447 force_single_succ_latches (void)
1453 FOR_EACH_LOOP (li, loop, 0)
1455 if (loop->latch != loop->header && single_succ_p (loop->latch))
1458 e = find_edge (loop->latch, loop->header);
1462 loops_state_set (LOOPS_HAVE_SIMPLE_LATCHES);
1465 /* This function is called from loop_version. It splits the entry edge
1466 of the loop we want to version, adds the versioning condition, and
1467 adjust the edges to the two versions of the loop appropriately.
1468 e is an incoming edge. Returns the basic block containing the
1471 --- edge e ---- > [second_head]
1473 Split it and insert new conditional expression and adjust edges.
1475 --- edge e ---> [cond expr] ---> [first_head]
1477 +---------> [second_head]
1479 THEN_PROB is the probability of then branch of the condition. */
1482 lv_adjust_loop_entry_edge (basic_block first_head, basic_block second_head,
1483 edge e, void *cond_expr, unsigned then_prob)
1485 basic_block new_head = NULL;
1488 gcc_assert (e->dest == second_head);
1490 /* Split edge 'e'. This will create a new basic block, where we can
1491 insert conditional expr. */
1492 new_head = split_edge (e);
1494 lv_add_condition_to_bb (first_head, second_head, new_head,
1497 /* Don't set EDGE_TRUE_VALUE in RTL mode, as it's invalid there. */
1498 e = single_succ_edge (new_head);
1499 e1 = make_edge (new_head, first_head,
1500 current_ir_type () == IR_GIMPLE ? EDGE_TRUE_VALUE : 0);
1501 e1->probability = then_prob;
1502 e->probability = REG_BR_PROB_BASE - then_prob;
1503 e1->count = RDIV (e->count * e1->probability, REG_BR_PROB_BASE);
1504 e->count = RDIV (e->count * e->probability, REG_BR_PROB_BASE);
1506 set_immediate_dominator (CDI_DOMINATORS, first_head, new_head);
1507 set_immediate_dominator (CDI_DOMINATORS, second_head, new_head);
1509 /* Adjust loop header phi nodes. */
1510 lv_adjust_loop_header_phi (first_head, second_head, new_head, e1);
1515 /* Main entry point for Loop Versioning transformation.
1517 This transformation given a condition and a loop, creates
1518 -if (condition) { loop_copy1 } else { loop_copy2 },
1519 where loop_copy1 is the loop transformed in one way, and loop_copy2
1520 is the loop transformed in another way (or unchanged). 'condition'
1521 may be a run time test for things that were not resolved by static
1522 analysis (overlapping ranges (anti-aliasing), alignment, etc.).
1524 THEN_PROB is the probability of the then edge of the if. THEN_SCALE
1525 is the ratio by that the frequencies in the original loop should
1526 be scaled. ELSE_SCALE is the ratio by that the frequencies in the
1527 new loop should be scaled.
1529 If PLACE_AFTER is true, we place the new loop after LOOP in the
1530 instruction stream, otherwise it is placed before LOOP. */
1533 loop_version (struct loop *loop,
1534 void *cond_expr, basic_block *condition_bb,
1535 unsigned then_prob, unsigned then_scale, unsigned else_scale,
1538 basic_block first_head, second_head;
1539 edge entry, latch_edge, true_edge, false_edge;
1542 basic_block cond_bb;
1544 /* Record entry and latch edges for the loop */
1545 entry = loop_preheader_edge (loop);
1546 irred_flag = entry->flags & EDGE_IRREDUCIBLE_LOOP;
1547 entry->flags &= ~EDGE_IRREDUCIBLE_LOOP;
1549 /* Note down head of loop as first_head. */
1550 first_head = entry->dest;
1552 /* Duplicate loop. */
1553 if (!cfg_hook_duplicate_loop_to_header_edge (loop, entry, 1,
1554 NULL, NULL, NULL, 0))
1556 entry->flags |= irred_flag;
1560 /* After duplication entry edge now points to new loop head block.
1561 Note down new head as second_head. */
1562 second_head = entry->dest;
1564 /* Split loop entry edge and insert new block with cond expr. */
1565 cond_bb = lv_adjust_loop_entry_edge (first_head, second_head,
1566 entry, cond_expr, then_prob);
1568 *condition_bb = cond_bb;
1572 entry->flags |= irred_flag;
1576 latch_edge = single_succ_edge (get_bb_copy (loop->latch));
1578 extract_cond_bb_edges (cond_bb, &true_edge, &false_edge);
1579 nloop = loopify (latch_edge,
1580 single_pred_edge (get_bb_copy (loop->header)),
1581 cond_bb, true_edge, false_edge,
1582 false /* Do not redirect all edges. */,
1583 then_scale, else_scale);
1585 /* loopify redirected latch_edge. Update its PENDING_STMTS. */
1586 lv_flush_pending_stmts (latch_edge);
1588 /* loopify redirected condition_bb's succ edge. Update its PENDING_STMTS. */
1589 extract_cond_bb_edges (cond_bb, &true_edge, &false_edge);
1590 lv_flush_pending_stmts (false_edge);
1591 /* Adjust irreducible flag. */
1594 cond_bb->flags |= BB_IRREDUCIBLE_LOOP;
1595 loop_preheader_edge (loop)->flags |= EDGE_IRREDUCIBLE_LOOP;
1596 loop_preheader_edge (nloop)->flags |= EDGE_IRREDUCIBLE_LOOP;
1597 single_pred_edge (cond_bb)->flags |= EDGE_IRREDUCIBLE_LOOP;
1602 basic_block *bbs = get_loop_body_in_dom_order (nloop), after;
1605 after = loop->latch;
1607 for (i = 0; i < nloop->num_nodes; i++)
1609 move_block_after (bbs[i], after);
1615 /* At this point condition_bb is loop preheader with two successors,
1616 first_head and second_head. Make sure that loop preheader has only
1618 split_edge (loop_preheader_edge (loop));
1619 split_edge (loop_preheader_edge (nloop));
1624 /* The structure of loops might have changed. Some loops might get removed
1625 (and their headers and latches were set to NULL), loop exists might get
1626 removed (thus the loop nesting may be wrong), and some blocks and edges
1627 were changed (so the information about bb --> loop mapping does not have
1628 to be correct). But still for the remaining loops the header dominates
1629 the latch, and loops did not get new subloops (new loops might possibly
1630 get created, but we are not interested in them). Fix up the mess.
1632 If CHANGED_BBS is not NULL, basic blocks whose loop has changed are
1636 fix_loop_structure (bitmap changed_bbs)
1639 struct loop *loop, *ploop;
1641 bool record_exits = false;
1642 struct loop **superloop = XNEWVEC (struct loop *, number_of_loops ());
1644 /* Remove the old bb -> loop mapping. Remember the depth of the blocks in
1645 the loop hierarchy, so that we can recognize blocks whose loop nesting
1646 relationship has changed. */
1650 bb->aux = (void *) (size_t) loop_depth (bb->loop_father);
1651 bb->loop_father = current_loops->tree_root;
1654 if (loops_state_satisfies_p (LOOPS_HAVE_RECORDED_EXITS))
1656 release_recorded_exits ();
1657 record_exits = true;
1660 /* Remove the dead loops from structures. We start from the innermost
1661 loops, so that when we remove the loops, we know that the loops inside
1662 are preserved, and do not waste time relinking loops that will be
1664 FOR_EACH_LOOP (li, loop, LI_FROM_INNERMOST)
1671 ploop = loop->inner;
1672 flow_loop_tree_node_remove (ploop);
1673 flow_loop_tree_node_add (loop_outer (loop), ploop);
1676 /* Remove the loop and free its data. */
1680 /* Rescan the bodies of loops, starting from the outermost ones. We assume
1681 that no optimization interchanges the order of the loops, i.e., it cannot
1682 happen that L1 was superloop of L2 before and it is subloop of L2 now
1683 (without explicitly updating loop information). At the same time, we also
1684 determine the new loop structure. */
1685 current_loops->tree_root->num_nodes = n_basic_blocks;
1686 FOR_EACH_LOOP (li, loop, 0)
1688 superloop[loop->num] = loop->header->loop_father;
1689 loop->num_nodes = flow_loop_nodes_find (loop->header, loop);
1692 /* Now fix the loop nesting. */
1693 FOR_EACH_LOOP (li, loop, 0)
1695 ploop = superloop[loop->num];
1696 if (ploop != loop_outer (loop))
1698 flow_loop_tree_node_remove (loop);
1699 flow_loop_tree_node_add (ploop, loop);
1704 /* Mark the blocks whose loop has changed. */
1709 if ((void *) (size_t) loop_depth (bb->loop_father) != bb->aux)
1710 bitmap_set_bit (changed_bbs, bb->index);
1716 if (loops_state_satisfies_p (LOOPS_HAVE_PREHEADERS))
1717 create_preheaders (CP_SIMPLE_PREHEADERS);
1719 if (loops_state_satisfies_p (LOOPS_HAVE_SIMPLE_LATCHES))
1720 force_single_succ_latches ();
1722 if (loops_state_satisfies_p (LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS))
1723 mark_irreducible_loops ();
1726 record_loop_exits ();
1728 #ifdef ENABLE_CHECKING
1729 verify_loop_structure ();