1 /* Loop manipulation code for GNU compiler.
2 Copyright (C) 2002, 2003, 2004 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 2, or (at your option) any later
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
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING. If not, write to the Free
18 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
23 #include "coretypes.h"
26 #include "hard-reg-set.h"
27 #include "basic-block.h"
29 #include "cfglayout.h"
32 static struct loop * duplicate_loop (struct loops *, struct loop *,
34 static void duplicate_subloops (struct loops *, struct loop *, struct loop *);
35 static void copy_loops_to (struct loops *, struct loop **, int,
37 static void loop_redirect_edge (edge, basic_block);
38 static bool loop_delete_branch_edge (edge, int);
39 static void remove_bbs (basic_block *, int);
40 static bool rpe_enum_p (basic_block, void *);
41 static int find_path (edge, basic_block **);
42 static bool alp_enum_p (basic_block, void *);
43 static void add_loop (struct loops *, struct loop *);
44 static void fix_loop_placements (struct loop *);
45 static bool fix_bb_placement (struct loops *, basic_block);
46 static void fix_bb_placements (struct loops *, basic_block);
47 static void place_new_loop (struct loops *, struct loop *);
48 static void scale_loop_frequencies (struct loop *, int, int);
49 static void scale_bbs_frequencies (basic_block *, int, int, int);
50 static basic_block create_preheader (struct loop *, int);
51 static void fix_irreducible_loops (basic_block);
53 /* Splits basic block BB after INSN, returns created edge. Updates loops
56 split_loop_bb (basic_block bb, rtx insn)
60 /* Split the block. */
61 e = split_block (bb, insn);
63 /* Add dest to loop. */
64 add_bb_to_loop (e->dest, e->src->loop_father);
69 /* Checks whether basic block BB is dominated by DATA. */
71 rpe_enum_p (basic_block bb, void *data)
73 return dominated_by_p (CDI_DOMINATORS, bb, data);
76 /* Remove basic blocks BBS from loop structure and dominance info,
77 and delete them afterwards. */
79 remove_bbs (basic_block *bbs, int nbbs)
83 for (i = 0; i < nbbs; i++)
85 remove_bb_from_loops (bbs[i]);
86 delete_basic_block (bbs[i]);
90 /* Find path -- i.e. the basic blocks dominated by edge E and put them
91 into array BBS, that will be allocated large enough to contain them.
92 E->dest must have exactly one predecessor for this to work (it is
93 easy to achieve and we do not put it here because we do not want to
94 alter anything by this function). The number of basic blocks in the
97 find_path (edge e, basic_block **bbs)
99 if (e->dest->pred->pred_next)
102 /* Find bbs in the path. */
103 *bbs = xcalloc (n_basic_blocks, sizeof (basic_block));
104 return dfs_enumerate_from (e->dest, 0, rpe_enum_p, *bbs,
105 n_basic_blocks, e->dest);
108 /* Fix placement of basic block BB inside loop hierarchy stored in LOOPS --
109 Let L be a loop to that BB belongs. Then every successor of BB must either
110 1) belong to some superloop of loop L, or
111 2) be a header of loop K such that K->outer is superloop of L
112 Returns true if we had to move BB into other loop to enforce this condition,
113 false if the placement of BB was already correct (provided that placements
114 of its successors are correct). */
116 fix_bb_placement (struct loops *loops, basic_block bb)
119 struct loop *loop = loops->tree_root, *act;
121 for (e = bb->succ; e; e = e->succ_next)
123 if (e->dest == EXIT_BLOCK_PTR)
126 act = e->dest->loop_father;
127 if (act->header == e->dest)
130 if (flow_loop_nested_p (loop, act))
134 if (loop == bb->loop_father)
137 remove_bb_from_loops (bb);
138 add_bb_to_loop (bb, loop);
143 /* Fix placements of basic blocks inside loop hierarchy stored in loops; i.e.
144 enforce condition condition stated in description of fix_bb_placement. We
145 start from basic block FROM that had some of its successors removed, so that
146 his placement no longer has to be correct, and iteratively fix placement of
147 its predecessors that may change if placement of FROM changed. Also fix
148 placement of subloops of FROM->loop_father, that might also be altered due
149 to this change; the condition for them is similar, except that instead of
150 successors we consider edges coming out of the loops. */
152 fix_bb_placements (struct loops *loops, basic_block from)
155 basic_block *queue, *qtop, *qbeg, *qend;
156 struct loop *base_loop;
159 /* We pass through blocks back-reachable from FROM, testing whether some
160 of their successors moved to outer loop. It may be necessary to
161 iterate several times, but it is finite, as we stop unless we move
162 the basic block up the loop structure. The whole story is a bit
163 more complicated due to presence of subloops, those are moved using
164 fix_loop_placement. */
166 base_loop = from->loop_father;
167 if (base_loop == loops->tree_root)
170 in_queue = sbitmap_alloc (last_basic_block);
171 sbitmap_zero (in_queue);
172 SET_BIT (in_queue, from->index);
173 /* Prevent us from going out of the base_loop. */
174 SET_BIT (in_queue, base_loop->header->index);
176 queue = xmalloc ((base_loop->num_nodes + 1) * sizeof (basic_block));
177 qtop = queue + base_loop->num_nodes + 1;
188 RESET_BIT (in_queue, from->index);
190 if (from->loop_father->header == from)
192 /* Subloop header, maybe move the loop upward. */
193 if (!fix_loop_placement (from->loop_father))
198 /* Ordinary basic block. */
199 if (!fix_bb_placement (loops, from))
203 /* Something has changed, insert predecessors into queue. */
204 for (e = from->pred; e; e = e->pred_next)
206 basic_block pred = e->src;
209 if (TEST_BIT (in_queue, pred->index))
212 /* If it is subloop, then it either was not moved, or
213 the path up the loop tree from base_loop do not contain
215 nca = find_common_loop (pred->loop_father, base_loop);
216 if (pred->loop_father != base_loop
218 || nca != pred->loop_father))
219 pred = pred->loop_father->header;
220 else if (!flow_loop_nested_p (from->loop_father, pred->loop_father))
222 /* No point in processing it. */
226 if (TEST_BIT (in_queue, pred->index))
229 /* Schedule the basic block. */
234 SET_BIT (in_queue, pred->index);
241 /* Basic block from has lost one or more of its predecessors, so it might
242 mo longer be part irreducible loop. Fix it and proceed recursively
243 for its successors if needed. */
245 fix_irreducible_loops (basic_block from)
254 if (!(from->flags & BB_IRREDUCIBLE_LOOP))
257 on_stack = sbitmap_alloc (last_basic_block);
258 sbitmap_zero (on_stack);
259 SET_BIT (on_stack, from->index);
260 stack = xmalloc (from->loop_father->num_nodes * sizeof (basic_block));
266 bb = stack[--stack_top];
267 RESET_BIT (on_stack, bb->index);
269 for (e = bb->pred; e; e = e->pred_next)
270 if (e->flags & EDGE_IRREDUCIBLE_LOOP)
275 bb->flags &= ~BB_IRREDUCIBLE_LOOP;
276 if (bb->loop_father->header == bb)
277 edges = get_loop_exit_edges (bb->loop_father, &n_edges);
281 for (e = bb->succ; e; e = e->succ_next)
283 edges = xmalloc (n_edges * sizeof (edge));
285 for (e = bb->succ; e; e = e->succ_next)
286 edges[n_edges++] = e;
289 for (i = 0; i < n_edges; i++)
293 if (e->flags & EDGE_IRREDUCIBLE_LOOP)
295 if (!flow_bb_inside_loop_p (from->loop_father, e->dest))
298 e->flags &= ~EDGE_IRREDUCIBLE_LOOP;
299 if (TEST_BIT (on_stack, e->dest->index))
302 SET_BIT (on_stack, e->dest->index);
303 stack[stack_top++] = e->dest;
313 /* Removes path beginning at edge E, i.e. remove basic blocks dominated by E
314 and update loop structure stored in LOOPS and dominators. Return true if
315 we were able to remove the path, false otherwise (and nothing is affected
318 remove_path (struct loops *loops, edge e)
321 basic_block *rem_bbs, *bord_bbs, *dom_bbs, from, bb;
322 int i, nrem, n_bord_bbs, n_dom_bbs;
325 if (!loop_delete_branch_edge (e, 0))
328 /* We need to check whether basic blocks are dominated by the edge
329 e, but we only have basic block dominators. This is easy to
330 fix -- when e->dest has exactly one predecessor, this corresponds
331 to blocks dominated by e->dest, if not, split the edge. */
332 if (e->dest->pred->pred_next)
333 e = loop_split_edge_with (e, NULL_RTX)->pred;
335 /* It may happen that by removing path we remove one or more loops
336 we belong to. In this case first unloop the loops, then proceed
337 normally. We may assume that e->dest is not a header of any loop,
338 as it now has exactly one predecessor. */
339 while (e->src->loop_father->outer
340 && dominated_by_p (CDI_DOMINATORS,
341 e->src->loop_father->latch, e->dest))
342 unloop (loops, e->src->loop_father);
344 /* Identify the path. */
345 nrem = find_path (e, &rem_bbs);
348 bord_bbs = xcalloc (n_basic_blocks, sizeof (basic_block));
349 seen = sbitmap_alloc (last_basic_block);
352 /* Find "border" hexes -- i.e. those with predecessor in removed path. */
353 for (i = 0; i < nrem; i++)
354 SET_BIT (seen, rem_bbs[i]->index);
355 for (i = 0; i < nrem; i++)
358 for (ae = rem_bbs[i]->succ; ae; ae = ae->succ_next)
359 if (ae->dest != EXIT_BLOCK_PTR && !TEST_BIT (seen, ae->dest->index))
361 SET_BIT (seen, ae->dest->index);
362 bord_bbs[n_bord_bbs++] = ae->dest;
366 /* Remove the path. */
368 if (!loop_delete_branch_edge (e, 1))
370 dom_bbs = xcalloc (n_basic_blocks, sizeof (basic_block));
372 /* Cancel loops contained in the path. */
373 for (i = 0; i < nrem; i++)
374 if (rem_bbs[i]->loop_father->header == rem_bbs[i])
375 cancel_loop_tree (loops, rem_bbs[i]->loop_father);
377 remove_bbs (rem_bbs, nrem);
380 /* Find blocks whose dominators may be affected. */
383 for (i = 0; i < n_bord_bbs; i++)
387 bb = get_immediate_dominator (CDI_DOMINATORS, bord_bbs[i]);
388 if (TEST_BIT (seen, bb->index))
390 SET_BIT (seen, bb->index);
392 for (ldom = first_dom_son (CDI_DOMINATORS, bb);
394 ldom = next_dom_son (CDI_DOMINATORS, ldom))
395 if (!dominated_by_p (CDI_DOMINATORS, from, ldom))
396 dom_bbs[n_dom_bbs++] = ldom;
401 /* Recount dominators. */
402 iterate_fix_dominators (CDI_DOMINATORS, dom_bbs, n_dom_bbs);
405 /* These blocks have lost some predecessor(s), thus their irreducible
406 status could be changed. */
407 for (i = 0; i < n_bord_bbs; i++)
408 fix_irreducible_loops (bord_bbs[i]);
411 /* Fix placements of basic blocks inside loops and the placement of
412 loops in the loop tree. */
413 fix_bb_placements (loops, from);
414 fix_loop_placements (from->loop_father);
419 /* Predicate for enumeration in add_loop. */
421 alp_enum_p (basic_block bb, void *alp_header)
423 return bb != (basic_block) alp_header;
426 /* Given LOOP structure with filled header and latch, find the body of the
427 corresponding loop and add it to LOOPS tree. */
429 add_loop (struct loops *loops, struct loop *loop)
434 /* Add it to loop structure. */
435 place_new_loop (loops, loop);
438 /* Find its nodes. */
439 bbs = xcalloc (n_basic_blocks, sizeof (basic_block));
440 n = dfs_enumerate_from (loop->latch, 1, alp_enum_p,
441 bbs, n_basic_blocks, loop->header);
443 for (i = 0; i < n; i++)
444 add_bb_to_loop (bbs[i], loop);
445 add_bb_to_loop (loop->header, loop);
450 /* Multiply all frequencies of basic blocks in array BBS of length NBBS
453 scale_bbs_frequencies (basic_block *bbs, int nbbs, int num, int den)
458 for (i = 0; i < nbbs; i++)
460 bbs[i]->frequency = (bbs[i]->frequency * num) / den;
461 bbs[i]->count = (bbs[i]->count * num) / den;
462 for (e = bbs[i]->succ; e; e = e->succ_next)
463 e->count = (e->count * num) /den;
467 /* Multiply all frequencies in LOOP by NUM/DEN. */
469 scale_loop_frequencies (struct loop *loop, int num, int den)
473 bbs = get_loop_body (loop);
474 scale_bbs_frequencies (bbs, loop->num_nodes, num, den);
478 /* Make area between HEADER_EDGE and LATCH_EDGE a loop by connecting
479 latch to header and update loop tree stored in LOOPS and dominators
480 accordingly. Everything between them plus LATCH_EDGE destination must
481 be dominated by HEADER_EDGE destination, and back-reachable from
482 LATCH_EDGE source. HEADER_EDGE is redirected to basic block SWITCH_BB,
483 SWITCH_BB->succ to original destination of LATCH_EDGE and
484 SWITCH_BB->succ->succ_next to original destination of HEADER_EDGE.
485 Returns newly created loop. */
487 loopify (struct loops *loops, edge latch_edge, edge header_edge, basic_block switch_bb)
489 basic_block succ_bb = latch_edge->dest;
490 basic_block pred_bb = header_edge->src;
491 basic_block *dom_bbs, *body;
492 unsigned n_dom_bbs, i;
494 struct loop *loop = xcalloc (1, sizeof (struct loop));
495 struct loop *outer = succ_bb->loop_father->outer;
496 int freq, prob, tot_prob;
500 loop->header = header_edge->dest;
501 loop->latch = latch_edge->src;
503 freq = EDGE_FREQUENCY (header_edge);
504 cnt = header_edge->count;
505 prob = switch_bb->succ->probability;
506 tot_prob = prob + switch_bb->succ->succ_next->probability;
510 /* Redirect edges. */
511 loop_redirect_edge (latch_edge, loop->header);
512 loop_redirect_edge (header_edge, switch_bb);
513 loop_redirect_edge (switch_bb->succ->succ_next, loop->header);
514 loop_redirect_edge (switch_bb->succ, succ_bb);
516 /* Update dominators. */
517 set_immediate_dominator (CDI_DOMINATORS, switch_bb, pred_bb);
518 set_immediate_dominator (CDI_DOMINATORS, loop->header, switch_bb);
519 set_immediate_dominator (CDI_DOMINATORS, succ_bb, switch_bb);
521 /* Compute new loop. */
522 add_loop (loops, loop);
523 flow_loop_tree_node_add (outer, loop);
525 /* Add switch_bb to appropriate loop. */
526 add_bb_to_loop (switch_bb, outer);
528 /* Fix frequencies. */
529 switch_bb->frequency = freq;
530 switch_bb->count = cnt;
531 for (e = switch_bb->succ; e; e = e->succ_next)
532 e->count = (switch_bb->count * e->probability) / REG_BR_PROB_BASE;
533 scale_loop_frequencies (loop, prob, tot_prob);
534 scale_loop_frequencies (succ_bb->loop_father, tot_prob - prob, tot_prob);
536 /* Update dominators of blocks outside of LOOP. */
537 dom_bbs = xcalloc (n_basic_blocks, sizeof (basic_block));
539 seen = sbitmap_alloc (last_basic_block);
541 body = get_loop_body (loop);
543 for (i = 0; i < loop->num_nodes; i++)
544 SET_BIT (seen, body[i]->index);
546 for (i = 0; i < loop->num_nodes; i++)
550 for (ldom = first_dom_son (CDI_DOMINATORS, body[i]);
552 ldom = next_dom_son (CDI_DOMINATORS, ldom))
553 if (!TEST_BIT (seen, ldom->index))
555 SET_BIT (seen, ldom->index);
556 dom_bbs[n_dom_bbs++] = ldom;
560 iterate_fix_dominators (CDI_DOMINATORS, dom_bbs, n_dom_bbs);
569 /* Remove the latch edge of a LOOP and update LOOPS tree to indicate that
570 the LOOP was removed. After this function, original loop latch will
571 have no successor, which caller is expected to fix somehow. */
573 unloop (struct loops *loops, struct loop *loop)
578 basic_block latch = loop->latch;
582 /* This is relatively straightforward. The dominators are unchanged, as
583 loop header dominates loop latch, so the only thing we have to care of
584 is the placement of loops and basic blocks inside the loop tree. We
585 move them all to the loop->outer, and then let fix_bb_placements do
588 body = get_loop_body (loop);
589 edges = get_loop_exit_edges (loop, &n_edges);
591 for (i = 0; i < n; i++)
592 if (body[i]->loop_father == loop)
594 remove_bb_from_loops (body[i]);
595 add_bb_to_loop (body[i], loop->outer);
602 flow_loop_tree_node_remove (ploop);
603 flow_loop_tree_node_add (loop->outer, ploop);
606 /* Remove the loop and free its data. */
607 flow_loop_tree_node_remove (loop);
608 loops->parray[loop->num] = NULL;
609 flow_loop_free (loop);
611 remove_edge (latch->succ);
612 fix_bb_placements (loops, latch);
614 /* If the loop was inside an irreducible region, we would have to somehow
615 update the irreducible marks inside its body. While it is certainly
616 possible to do, it is a bit complicated and this situation should be
617 very rare, so we just remark all loops in this case. */
618 for (i = 0; i < n_edges; i++)
619 if (edges[i]->flags & EDGE_IRREDUCIBLE_LOOP)
622 mark_irreducible_loops (loops);
626 /* Fix placement of LOOP inside loop tree, i.e. find the innermost superloop
627 FATHER of LOOP such that all of the edges coming out of LOOP belong to
628 FATHER, and set it as outer loop of LOOP. Return 1 if placement of
631 fix_loop_placement (struct loop *loop)
636 struct loop *father = loop->pred[0], *act;
638 body = get_loop_body (loop);
639 for (i = 0; i < loop->num_nodes; i++)
640 for (e = body[i]->succ; e; e = e->succ_next)
641 if (!flow_bb_inside_loop_p (loop, e->dest))
643 act = find_common_loop (loop, e->dest->loop_father);
644 if (flow_loop_nested_p (father, act))
649 if (father != loop->outer)
651 for (act = loop->outer; act != father; act = act->outer)
652 act->num_nodes -= loop->num_nodes;
653 flow_loop_tree_node_remove (loop);
654 flow_loop_tree_node_add (father, loop);
660 /* Fix placement of superloops of LOOP inside loop tree, i.e. ensure that
661 condition stated in description of fix_loop_placement holds for them.
662 It is used in case when we removed some edges coming out of LOOP, which
663 may cause the right placement of LOOP inside loop tree to change. */
665 fix_loop_placements (struct loop *loop)
672 if (!fix_loop_placement (loop))
678 /* Creates place for a new LOOP in LOOPS structure. */
680 place_new_loop (struct loops *loops, struct loop *loop)
683 xrealloc (loops->parray, (loops->num + 1) * sizeof (struct loop *));
684 loops->parray[loops->num] = loop;
686 loop->num = loops->num++;
689 /* Copies copy of LOOP as subloop of TARGET loop, placing newly
690 created loop into LOOPS structure. */
692 duplicate_loop (struct loops *loops, struct loop *loop, struct loop *target)
695 cloop = xcalloc (1, sizeof (struct loop));
696 place_new_loop (loops, cloop);
698 /* Initialize copied loop. */
699 cloop->level = loop->level;
701 /* Set it as copy of loop. */
704 /* Add it to target. */
705 flow_loop_tree_node_add (target, cloop);
710 /* Copies structure of subloops of LOOP into TARGET loop, placing
711 newly created loops into loop tree stored in LOOPS. */
713 duplicate_subloops (struct loops *loops, struct loop *loop, struct loop *target)
715 struct loop *aloop, *cloop;
717 for (aloop = loop->inner; aloop; aloop = aloop->next)
719 cloop = duplicate_loop (loops, aloop, target);
720 duplicate_subloops (loops, aloop, cloop);
724 /* Copies structure of subloops of N loops, stored in array COPIED_LOOPS,
725 into TARGET loop, placing newly created loops into loop tree LOOPS. */
727 copy_loops_to (struct loops *loops, struct loop **copied_loops, int n, struct loop *target)
732 for (i = 0; i < n; i++)
734 aloop = duplicate_loop (loops, copied_loops[i], target);
735 duplicate_subloops (loops, copied_loops[i], aloop);
739 /* Redirects edge E to basic block DEST. */
741 loop_redirect_edge (edge e, basic_block dest)
746 redirect_edge_and_branch_force (e, dest);
749 /* Deletes edge E from a branch if possible. Unless REALLY_DELETE is set,
750 just test whether it is possible to remove the edge. */
752 loop_delete_branch_edge (edge e, int really_delete)
754 basic_block src = e->src;
758 if (src->succ->succ_next)
762 /* Cannot handle more than two exit edges. */
763 if (src->succ->succ_next->succ_next)
765 /* And it must be just a simple branch. */
766 if (!any_condjump_p (BB_END (src)))
769 snd = e == src->succ ? src->succ->succ_next : src->succ;
771 if (newdest == EXIT_BLOCK_PTR)
774 /* Hopefully the above conditions should suffice. */
778 /* Redirecting behaves wrongly wrto this flag. */
779 irr = snd->flags & EDGE_IRREDUCIBLE_LOOP;
781 if (!redirect_edge_and_branch (e, newdest))
783 src->succ->flags &= ~EDGE_IRREDUCIBLE_LOOP;
784 src->succ->flags |= irr;
790 /* Cannot happen -- we are using this only to remove an edge
795 return false; /* To avoid warning, cannot get here. */
798 /* Check whether LOOP's body can be duplicated. */
800 can_duplicate_loop_p (struct loop *loop)
803 basic_block *bbs = get_loop_body (loop);
805 ret = can_copy_bbs_p (bbs, loop->num_nodes);
811 #define RDIV(X,Y) (((X) + (Y) / 2) / (Y))
813 /* Duplicates body of LOOP to given edge E NDUPL times. Takes care of updating
814 LOOPS structure and dominators. E's destination must be LOOP header for
815 this to work, i.e. it must be entry or latch edge of this loop; these are
816 unique, as the loops must have preheaders for this function to work
817 correctly (in case E is latch, the function unrolls the loop, if E is entry
818 edge, it peels the loop). Store edges created by copying ORIG edge from
819 copies corresponding to set bits in WONT_EXIT bitmap (bit 0 corresponds to
820 original LOOP body, the other copies are numbered in order given by control
821 flow through them) into TO_REMOVE array. Returns false if duplication is
824 duplicate_loop_to_header_edge (struct loop *loop, edge e, struct loops *loops,
825 unsigned int ndupl, sbitmap wont_exit,
826 edge orig, edge *to_remove,
827 unsigned int *n_to_remove, int flags)
829 struct loop *target, *aloop;
830 struct loop **orig_loops;
831 unsigned n_orig_loops;
832 basic_block header = loop->header, latch = loop->latch;
833 basic_block *new_bbs, *bbs, *first_active;
834 basic_block new_bb, bb, first_active_latch = NULL;
836 edge spec_edges[2], new_spec_edges[2];
840 int is_latch = (latch == e->src);
841 int scale_act = 0, *scale_step = NULL, scale_main = 0;
842 int p, freq_in, freq_le, freq_out_orig;
843 int prob_pass_thru, prob_pass_wont_exit, prob_pass_main;
844 int add_irreducible_flag;
846 if (e->dest != loop->header)
853 /* Orig must be edge out of the loop. */
854 if (!flow_bb_inside_loop_p (loop, orig->src))
856 if (flow_bb_inside_loop_p (loop, orig->dest))
860 bbs = get_loop_body (loop);
862 /* Check whether duplication is possible. */
863 if (!can_copy_bbs_p (bbs, loop->num_nodes))
868 new_bbs = xmalloc (sizeof (basic_block) * loop->num_nodes);
870 /* In case we are doing loop peeling and the loop is in the middle of
871 irreducible region, the peeled copies will be inside it too. */
872 add_irreducible_flag = e->flags & EDGE_IRREDUCIBLE_LOOP;
873 if (is_latch && add_irreducible_flag)
876 /* Find edge from latch. */
877 latch_edge = loop_latch_edge (loop);
879 if (flags & DLTHE_FLAG_UPDATE_FREQ)
881 /* Calculate coefficients by that we have to scale frequencies
882 of duplicated loop bodies. */
883 freq_in = header->frequency;
884 freq_le = EDGE_FREQUENCY (latch_edge);
887 if (freq_in < freq_le)
889 freq_out_orig = orig ? EDGE_FREQUENCY (orig) : freq_in - freq_le;
890 if (freq_out_orig > freq_in - freq_le)
891 freq_out_orig = freq_in - freq_le;
892 prob_pass_thru = RDIV (REG_BR_PROB_BASE * freq_le, freq_in);
893 prob_pass_wont_exit =
894 RDIV (REG_BR_PROB_BASE * (freq_le + freq_out_orig), freq_in);
896 scale_step = xmalloc (ndupl * sizeof (int));
898 for (i = 1; i <= ndupl; i++)
899 scale_step[i - 1] = TEST_BIT (wont_exit, i)
900 ? prob_pass_wont_exit
905 prob_pass_main = TEST_BIT (wont_exit, 0)
906 ? prob_pass_wont_exit
909 scale_main = REG_BR_PROB_BASE;
910 for (i = 0; i < ndupl; i++)
913 p = RDIV (p * scale_step[i], REG_BR_PROB_BASE);
915 scale_main = RDIV (REG_BR_PROB_BASE * REG_BR_PROB_BASE, scale_main);
916 scale_act = RDIV (scale_main * prob_pass_main, REG_BR_PROB_BASE);
920 scale_main = REG_BR_PROB_BASE;
921 for (i = 0; i < ndupl; i++)
922 scale_main = RDIV (scale_main * scale_step[i], REG_BR_PROB_BASE);
923 scale_act = REG_BR_PROB_BASE - prob_pass_thru;
925 for (i = 0; i < ndupl; i++)
926 if (scale_step[i] < 0 || scale_step[i] > REG_BR_PROB_BASE)
928 if (scale_main < 0 || scale_main > REG_BR_PROB_BASE
929 || scale_act < 0 || scale_act > REG_BR_PROB_BASE)
933 /* Loop the new bbs will belong to. */
934 target = e->src->loop_father;
936 /* Original loops. */
938 for (aloop = loop->inner; aloop; aloop = aloop->next)
940 orig_loops = xcalloc (n_orig_loops, sizeof (struct loop *));
941 for (aloop = loop->inner, i = 0; aloop; aloop = aloop->next, i++)
942 orig_loops[i] = aloop;
948 first_active = xmalloc (n * sizeof (basic_block));
951 memcpy (first_active, bbs, n * sizeof (basic_block));
952 first_active_latch = latch;
955 /* Record exit edge in original loop body. */
956 if (orig && TEST_BIT (wont_exit, 0))
957 to_remove[(*n_to_remove)++] = orig;
959 spec_edges[SE_ORIG] = orig;
960 spec_edges[SE_LATCH] = latch_edge;
962 for (j = 0; j < ndupl; j++)
965 copy_loops_to (loops, orig_loops, n_orig_loops, target);
968 copy_bbs (bbs, n, new_bbs, spec_edges, 2, new_spec_edges, loop);
970 /* Note whether the blocks and edges belong to an irreducible loop. */
971 if (add_irreducible_flag)
973 for (i = 0; i < n; i++)
974 new_bbs[i]->rbi->duplicated = 1;
975 for (i = 0; i < n; i++)
978 if (new_bb->loop_father == target)
979 new_bb->flags |= BB_IRREDUCIBLE_LOOP;
981 for (ae = new_bb->succ; ae; ae = ae->succ_next)
982 if (ae->dest->rbi->duplicated
983 && (ae->src->loop_father == target
984 || ae->dest->loop_father == target))
985 ae->flags |= EDGE_IRREDUCIBLE_LOOP;
987 for (i = 0; i < n; i++)
988 new_bbs[i]->rbi->duplicated = 0;
991 /* Redirect the special edges. */
994 redirect_edge_and_branch_force (latch_edge, new_bbs[0]);
995 redirect_edge_and_branch_force (new_spec_edges[SE_LATCH],
997 set_immediate_dominator (CDI_DOMINATORS, new_bbs[0], latch);
998 latch = loop->latch = new_bbs[1];
999 e = latch_edge = new_spec_edges[SE_LATCH];
1003 redirect_edge_and_branch_force (new_spec_edges[SE_LATCH],
1005 redirect_edge_and_branch_force (e, new_bbs[0]);
1006 set_immediate_dominator (CDI_DOMINATORS, new_bbs[0], e->src);
1007 e = new_spec_edges[SE_LATCH];
1010 /* Record exit edge in this copy. */
1011 if (orig && TEST_BIT (wont_exit, j + 1))
1012 to_remove[(*n_to_remove)++] = new_spec_edges[SE_ORIG];
1014 /* Record the first copy in the control flow order if it is not
1015 the original loop (i.e. in case of peeling). */
1016 if (!first_active_latch)
1018 memcpy (first_active, new_bbs, n * sizeof (basic_block));
1019 first_active_latch = new_bbs[1];
1022 /* Set counts and frequencies. */
1023 if (flags & DLTHE_FLAG_UPDATE_FREQ)
1025 scale_bbs_frequencies (new_bbs, n, scale_act, REG_BR_PROB_BASE);
1026 scale_act = RDIV (scale_act * scale_step[j], REG_BR_PROB_BASE);
1032 /* Update the original loop. */
1034 set_immediate_dominator (CDI_DOMINATORS, e->dest, e->src);
1035 if (flags & DLTHE_FLAG_UPDATE_FREQ)
1037 scale_bbs_frequencies (bbs, n, scale_main, REG_BR_PROB_BASE);
1041 /* Update dominators of outer blocks if affected. */
1042 for (i = 0; i < n; i++)
1044 basic_block dominated, dom_bb, *dom_bbs;
1048 n_dom_bbs = get_dominated_by (CDI_DOMINATORS, bb, &dom_bbs);
1049 for (j = 0; j < n_dom_bbs; j++)
1051 dominated = dom_bbs[j];
1052 if (flow_bb_inside_loop_p (loop, dominated))
1054 dom_bb = nearest_common_dominator (
1055 CDI_DOMINATORS, first_active[i], first_active_latch);
1056 set_immediate_dominator (CDI_DOMINATORS, dominated, dom_bb);
1060 free (first_active);
1067 /* A callback for make_forwarder block, to redirect all edges except for
1068 MFB_KJ_EDGE to the entry part. E is the edge for that we should decide
1069 whether to redirect it. */
1071 static edge mfb_kj_edge;
1073 mfb_keep_just (edge e)
1075 return e != mfb_kj_edge;
1078 /* A callback for make_forwarder block, to update data structures for a basic
1079 block JUMP created by redirecting an edge (only the latch edge is being
1083 mfb_update_loops (basic_block jump)
1085 struct loop *loop = jump->succ->dest->loop_father;
1087 if (dom_computed[CDI_DOMINATORS])
1088 set_immediate_dominator (CDI_DOMINATORS, jump, jump->pred->src);
1089 add_bb_to_loop (jump, loop);
1093 /* Creates a pre-header for a LOOP. Returns newly created block. Unless
1094 CP_SIMPLE_PREHEADERS is set in FLAGS, we only force LOOP to have single
1095 entry; otherwise we also force preheader block to have only one successor.
1096 The function also updates dominators. */
1099 create_preheader (struct loop *loop, int flags)
1103 struct loop *cloop, *ploop;
1107 cloop = loop->outer;
1109 for (e = loop->header->pred; e; e = e->pred_next)
1111 if (e->src == loop->latch)
1113 irred |= (e->flags & EDGE_IRREDUCIBLE_LOOP) != 0;
1120 for (e = loop->header->pred; e->src == loop->latch; e = e->pred_next);
1121 if (!(flags & CP_SIMPLE_PREHEADERS)
1122 || !e->src->succ->succ_next)
1126 mfb_kj_edge = loop_latch_edge (loop);
1127 fallthru = make_forwarder_block (loop->header, mfb_keep_just,
1129 dummy = fallthru->src;
1130 loop->header = fallthru->dest;
1132 /* The header could be a latch of some superloop(s); due to design of
1133 split_block, it would now move to fallthru->dest. */
1134 for (ploop = loop; ploop; ploop = ploop->outer)
1135 if (ploop->latch == dummy)
1136 ploop->latch = fallthru->dest;
1138 /* Reorganize blocks so that the preheader is not stuck in the middle of the
1140 for (e = dummy->pred; e; e = e->pred_next)
1141 if (e->src != loop->latch)
1143 move_block_after (dummy, e->src);
1145 loop->header->loop_father = loop;
1146 add_bb_to_loop (dummy, cloop);
1150 dummy->flags |= BB_IRREDUCIBLE_LOOP;
1151 dummy->succ->flags |= EDGE_IRREDUCIBLE_LOOP;
1155 fprintf (rtl_dump_file, "Created preheader block for loop %i\n",
1161 /* Create preheaders for each loop from loop tree stored in LOOPS; for meaning
1162 of FLAGS see create_preheader. */
1164 create_preheaders (struct loops *loops, int flags)
1167 for (i = 1; i < loops->num; i++)
1168 create_preheader (loops->parray[i], flags);
1169 loops->state |= LOOPS_HAVE_PREHEADERS;
1172 /* Forces all loop latches of loops from loop tree LOOPS to have only single
1175 force_single_succ_latches (struct loops *loops)
1181 for (i = 1; i < loops->num; i++)
1183 loop = loops->parray[i];
1184 if (loop->latch != loop->header
1185 && !loop->latch->succ->succ_next)
1188 for (e = loop->header->pred; e->src != loop->latch; e = e->pred_next)
1191 loop_split_edge_with (e, NULL_RTX);
1193 loops->state |= LOOPS_HAVE_SIMPLE_LATCHES;
1196 /* A quite stupid function to put INSNS on edge E. They are supposed to form
1197 just one basic block. Jumps in INSNS are not handled, so cfg do not have to
1198 be ok after this function. The created block is placed on correct place
1199 in LOOPS structure and its dominator is set. */
1201 loop_split_edge_with (edge e, rtx insns)
1203 basic_block src, dest, new_bb;
1204 struct loop *loop_c;
1210 loop_c = find_common_loop (src->loop_father, dest->loop_father);
1212 /* Create basic block for it. */
1214 new_bb = split_edge (e);
1215 add_bb_to_loop (new_bb, loop_c);
1216 new_bb->flags = insns ? BB_SUPERBLOCK : 0;
1218 new_e = new_bb->succ;
1219 if (e->flags & EDGE_IRREDUCIBLE_LOOP)
1221 new_bb->flags |= BB_IRREDUCIBLE_LOOP;
1222 new_e->flags |= EDGE_IRREDUCIBLE_LOOP;
1226 emit_insn_after (insns, BB_END (new_bb));
1228 if (dest->loop_father->latch == src)
1229 dest->loop_father->latch = new_bb;