1 /* Loop manipulation code for GNU compiler.
2 Copyright (C) 2002, 2003 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 (dominance_info
, basic_block
*, int);
40 static bool rpe_enum_p (basic_block
, void *);
41 static int find_path (edge
, dominance_info
, 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
*, dominance_info
, 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 (struct loops
*loops
, basic_block bb
, rtx insn
)
62 /* Split the block. */
63 e
= split_block (bb
, insn
);
65 /* Add dest to loop. */
66 add_bb_to_loop (e
->dest
, e
->src
->loop_father
);
69 add_to_dominance_info (loops
->cfg
.dom
, e
->dest
);
70 n_dom_bbs
= get_dominated_by (loops
->cfg
.dom
, e
->src
, &dom_bbs
);
71 for (i
= 0; i
< n_dom_bbs
; i
++)
72 set_immediate_dominator (loops
->cfg
.dom
, dom_bbs
[i
], e
->dest
);
74 set_immediate_dominator (loops
->cfg
.dom
, e
->dest
, e
->src
);
79 /* Checks whether basic block BB is dominated by RPE->DOM, where
80 RPE is passed through DATA. */
88 rpe_enum_p (basic_block bb
, void *data
)
90 struct rpe_data
*rpe
= data
;
91 return dominated_by_p (rpe
->doms
, bb
, rpe
->dom
);
94 /* Remove basic blocks BBS from loop structure and dominance info,
95 and delete them afterwards. */
97 remove_bbs (dominance_info dom
, basic_block
*bbs
, int nbbs
)
101 for (i
= 0; i
< nbbs
; i
++)
103 remove_bb_from_loops (bbs
[i
]);
104 delete_from_dominance_info (dom
, bbs
[i
]);
105 delete_block (bbs
[i
]);
109 /* Find path -- i.e. the basic blocks dominated by edge E and put them
110 into array BBS, that will be allocated large enough to contain them.
111 E->dest must have exactly one predecessor for this to work (it is
112 easy to achieve and we do not put it here because we do not want to
113 alter anything by this function). The number of basic blocks in the
116 find_path (edge e
, dominance_info doms
, basic_block
**bbs
)
120 if (e
->dest
->pred
->pred_next
)
123 /* Find bbs in the path. */
126 *bbs
= xcalloc (n_basic_blocks
, sizeof (basic_block
));
127 return dfs_enumerate_from (e
->dest
, 0, rpe_enum_p
, *bbs
,
128 n_basic_blocks
, &rpe
);
131 /* Fix placement of basic block BB inside loop hierarchy stored in LOOPS --
132 Let L be a loop to that BB belongs. Then every successor of BB must either
133 1) belong to some superloop of loop L, or
134 2) be a header of loop K such that K->outer is superloop of L
135 Returns true if we had to move BB into other loop to enforce this condition,
136 false if the placement of BB was already correct (provided that placements
137 of its successors are correct). */
139 fix_bb_placement (struct loops
*loops
, basic_block bb
)
142 struct loop
*loop
= loops
->tree_root
, *act
;
144 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
146 if (e
->dest
== EXIT_BLOCK_PTR
)
149 act
= e
->dest
->loop_father
;
150 if (act
->header
== e
->dest
)
153 if (flow_loop_nested_p (loop
, act
))
157 if (loop
== bb
->loop_father
)
160 remove_bb_from_loops (bb
);
161 add_bb_to_loop (bb
, loop
);
166 /* Fix placements of basic blocks inside loop hierarchy stored in loops; i.e.
167 enforce condition condition stated in description of fix_bb_placement. We
168 start from basic block FROM that had some of its successors removed, so that
169 his placement no longer has to be correct, and iteratively fix placement of
170 its predecessors that may change if placement of FROM changed. Also fix
171 placement of subloops of FROM->loop_father, that might also be altered due
172 to this change; the condition for them is similar, except that instead of
173 successors we consider edges coming out of the loops. */
175 fix_bb_placements (struct loops
*loops
, basic_block from
)
178 basic_block
*queue
, *qtop
, *qbeg
, *qend
;
179 struct loop
*base_loop
;
182 /* We pass through blocks back-reachable from FROM, testing whether some
183 of their successors moved to outer loop. It may be necessary to
184 iterate several times, but it is finite, as we stop unless we move
185 the basic block up the loop structure. The whole story is a bit
186 more complicated due to presence of subloops, those are moved using
187 fix_loop_placement. */
189 base_loop
= from
->loop_father
;
190 if (base_loop
== loops
->tree_root
)
193 in_queue
= sbitmap_alloc (last_basic_block
);
194 sbitmap_zero (in_queue
);
195 SET_BIT (in_queue
, from
->index
);
196 /* Prevent us from going out of the base_loop. */
197 SET_BIT (in_queue
, base_loop
->header
->index
);
199 queue
= xmalloc ((base_loop
->num_nodes
+ 1) * sizeof (basic_block
));
200 qtop
= queue
+ base_loop
->num_nodes
+ 1;
211 RESET_BIT (in_queue
, from
->index
);
213 if (from
->loop_father
->header
== from
)
215 /* Subloop header, maybe move the loop upward. */
216 if (!fix_loop_placement (from
->loop_father
))
221 /* Ordinary basic block. */
222 if (!fix_bb_placement (loops
, from
))
226 /* Something has changed, insert predecessors into queue. */
227 for (e
= from
->pred
; e
; e
= e
->pred_next
)
229 basic_block pred
= e
->src
;
232 if (TEST_BIT (in_queue
, pred
->index
))
235 /* If it is subloop, then it either was not moved, or
236 the path up the loop tree from base_loop do not contain
238 nca
= find_common_loop (pred
->loop_father
, base_loop
);
239 if (pred
->loop_father
!= base_loop
241 || nca
!= pred
->loop_father
))
242 pred
= pred
->loop_father
->header
;
243 else if (!flow_loop_nested_p (from
->loop_father
, pred
->loop_father
))
245 /* No point in processing it. */
249 if (TEST_BIT (in_queue
, pred
->index
))
252 /* Schedule the basic block. */
257 SET_BIT (in_queue
, pred
->index
);
264 /* Basic block from has lost one or more of its predecessors, so it might
265 mo longer be part irreducible loop. Fix it and proceed recursively
266 for its successors if needed. */
268 fix_irreducible_loops (basic_block from
)
277 if (!(from
->flags
& BB_IRREDUCIBLE_LOOP
))
280 on_stack
= sbitmap_alloc (last_basic_block
);
281 sbitmap_zero (on_stack
);
282 SET_BIT (on_stack
, from
->index
);
283 stack
= xmalloc (from
->loop_father
->num_nodes
* sizeof (basic_block
));
289 bb
= stack
[--stack_top
];
290 RESET_BIT (on_stack
, bb
->index
);
292 for (e
= bb
->pred
; e
; e
= e
->pred_next
)
293 if (e
->flags
& EDGE_IRREDUCIBLE_LOOP
)
298 bb
->flags
&= ~BB_IRREDUCIBLE_LOOP
;
299 if (bb
->loop_father
->header
== bb
)
300 edges
= get_loop_exit_edges (bb
->loop_father
, &n_edges
);
304 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
306 edges
= xmalloc (n_edges
* sizeof (edge
));
308 for (e
= bb
->succ
; e
; e
= e
->succ_next
)
309 edges
[n_edges
++] = e
;
312 for (i
= 0; i
< n_edges
; i
++)
313 if (e
->flags
& EDGE_IRREDUCIBLE_LOOP
)
315 if (!flow_bb_inside_loop_p (from
->loop_father
, e
->dest
))
318 e
->flags
&= ~EDGE_IRREDUCIBLE_LOOP
;
319 if (TEST_BIT (on_stack
, e
->dest
->index
))
322 SET_BIT (on_stack
, e
->dest
->index
);
323 stack
[stack_top
++] = e
->dest
;
332 /* Removes path beginning at edge E, i.e. remove basic blocks dominated by E
333 and update loop structure stored in LOOPS and dominators. Return true if
334 we were able to remove the path, false otherwise (and nothing is affected
337 remove_path (struct loops
*loops
, edge e
)
340 basic_block
*rem_bbs
, *bord_bbs
, *dom_bbs
, from
, bb
;
341 int i
, nrem
, n_bord_bbs
, n_dom_bbs
;
344 if (!loop_delete_branch_edge (e
, 0))
347 /* We need to check whether basic blocks are dominated by the edge
348 e, but we only have basic block dominators. This is easy to
349 fix -- when e->dest has exactly one predecessor, this corresponds
350 to blocks dominated by e->dest, if not, split the edge. */
351 if (e
->dest
->pred
->pred_next
)
352 e
= loop_split_edge_with (e
, NULL_RTX
, loops
)->pred
;
354 /* It may happen that by removing path we remove one or more loops
355 we belong to. In this case first unloop the loops, then proceed
356 normally. We may assume that e->dest is not a header of any loop,
357 as it now has exactly one predecessor. */
358 while (e
->src
->loop_father
->outer
359 && dominated_by_p (loops
->cfg
.dom
,
360 e
->src
->loop_father
->latch
, e
->dest
))
361 unloop (loops
, e
->src
->loop_father
);
363 /* Identify the path. */
364 nrem
= find_path (e
, loops
->cfg
.dom
, &rem_bbs
);
367 bord_bbs
= xcalloc (n_basic_blocks
, sizeof (basic_block
));
368 seen
= sbitmap_alloc (last_basic_block
);
371 /* Find "border" hexes -- i.e. those with predecessor in removed path. */
372 for (i
= 0; i
< nrem
; i
++)
373 SET_BIT (seen
, rem_bbs
[i
]->index
);
374 for (i
= 0; i
< nrem
; i
++)
377 for (ae
= rem_bbs
[i
]->succ
; ae
; ae
= ae
->succ_next
)
378 if (ae
->dest
!= EXIT_BLOCK_PTR
&& !TEST_BIT (seen
, ae
->dest
->index
))
380 SET_BIT (seen
, ae
->dest
->index
);
381 bord_bbs
[n_bord_bbs
++] = ae
->dest
;
385 /* Remove the path. */
387 if (!loop_delete_branch_edge (e
, 1))
389 dom_bbs
= xcalloc (n_basic_blocks
, sizeof (basic_block
));
391 /* Cancel loops contained in the path. */
392 for (i
= 0; i
< nrem
; i
++)
393 if (rem_bbs
[i
]->loop_father
->header
== rem_bbs
[i
])
394 cancel_loop_tree (loops
, rem_bbs
[i
]->loop_father
);
396 remove_bbs (loops
->cfg
.dom
, rem_bbs
, nrem
);
399 /* Find blocks whose dominators may be affected. */
402 for (i
= 0; i
< n_bord_bbs
; i
++)
407 bb
= get_immediate_dominator (loops
->cfg
.dom
, bord_bbs
[i
]);
408 if (TEST_BIT (seen
, bb
->index
))
410 SET_BIT (seen
, bb
->index
);
412 nldom
= get_dominated_by (loops
->cfg
.dom
, bb
, &ldom
);
413 for (j
= 0; j
< nldom
; j
++)
414 if (!dominated_by_p (loops
->cfg
.dom
, from
, ldom
[j
]))
415 dom_bbs
[n_dom_bbs
++] = ldom
[j
];
421 /* Recount dominators. */
422 iterate_fix_dominators (loops
->cfg
.dom
, dom_bbs
, n_dom_bbs
);
425 /* These blocks have lost some predecessor(s), thus their irreducible
426 status could be changed. */
427 for (i
= 0; i
< n_bord_bbs
; i
++)
428 fix_irreducible_loops (bord_bbs
[i
]);
431 /* Fix placements of basic blocks inside loops and the placement of
432 loops in the loop tree. */
433 fix_bb_placements (loops
, from
);
434 fix_loop_placements (from
->loop_father
);
439 /* Predicate for enumeration in add_loop. */
441 alp_enum_p (basic_block bb
, void *alp_header
)
443 return bb
!= (basic_block
) alp_header
;
446 /* Given LOOP structure with filled header and latch, find the body of the
447 corresponding loop and add it to LOOPS tree. */
449 add_loop (struct loops
*loops
, struct loop
*loop
)
454 /* Add it to loop structure. */
455 place_new_loop (loops
, loop
);
458 /* Find its nodes. */
459 bbs
= xcalloc (n_basic_blocks
, sizeof (basic_block
));
460 n
= dfs_enumerate_from (loop
->latch
, 1, alp_enum_p
,
461 bbs
, n_basic_blocks
, loop
->header
);
463 for (i
= 0; i
< n
; i
++)
464 add_bb_to_loop (bbs
[i
], loop
);
465 add_bb_to_loop (loop
->header
, loop
);
470 /* Multiply all frequencies of basic blocks in array BBS of length NBBS
473 scale_bbs_frequencies (basic_block
*bbs
, int nbbs
, int num
, int den
)
478 for (i
= 0; i
< nbbs
; i
++)
480 bbs
[i
]->frequency
= (bbs
[i
]->frequency
* num
) / den
;
481 bbs
[i
]->count
= (bbs
[i
]->count
* num
) / den
;
482 for (e
= bbs
[i
]->succ
; e
; e
= e
->succ_next
)
483 e
->count
= (e
->count
* num
) /den
;
487 /* Multiply all frequencies in LOOP by NUM/DEN. */
489 scale_loop_frequencies (struct loop
*loop
, int num
, int den
)
493 bbs
= get_loop_body (loop
);
494 scale_bbs_frequencies (bbs
, loop
->num_nodes
, num
, den
);
498 /* Make area between HEADER_EDGE and LATCH_EDGE a loop by connecting
499 latch to header and update loop tree stored in LOOPS and dominators
500 accordingly. Everything between them plus LATCH_EDGE destination must
501 be dominated by HEADER_EDGE destination, and back-reachable from
502 LATCH_EDGE source. HEADER_EDGE is redirected to basic block SWITCH_BB,
503 SWITCH_BB->succ to original destination of LATCH_EDGE and
504 SWITCH_BB->succ->succ_next to original destination of HEADER_EDGE.
505 Returns newly created loop. */
507 loopify (struct loops
*loops
, edge latch_edge
, edge header_edge
, basic_block switch_bb
)
509 basic_block succ_bb
= latch_edge
->dest
;
510 basic_block pred_bb
= header_edge
->src
;
511 basic_block
*dom_bbs
, *body
;
512 unsigned n_dom_bbs
, i
, j
;
514 struct loop
*loop
= xcalloc (1, sizeof (struct loop
));
515 struct loop
*outer
= succ_bb
->loop_father
->outer
;
516 int freq
, prob
, tot_prob
;
520 loop
->header
= header_edge
->dest
;
521 loop
->latch
= latch_edge
->src
;
523 freq
= EDGE_FREQUENCY (header_edge
);
524 cnt
= header_edge
->count
;
525 prob
= switch_bb
->succ
->probability
;
526 tot_prob
= prob
+ switch_bb
->succ
->succ_next
->probability
;
530 /* Redirect edges. */
531 loop_redirect_edge (latch_edge
, loop
->header
);
532 loop_redirect_edge (header_edge
, switch_bb
);
533 loop_redirect_edge (switch_bb
->succ
->succ_next
, loop
->header
);
534 loop_redirect_edge (switch_bb
->succ
, succ_bb
);
536 /* Update dominators. */
537 set_immediate_dominator (loops
->cfg
.dom
, switch_bb
, pred_bb
);
538 set_immediate_dominator (loops
->cfg
.dom
, loop
->header
, switch_bb
);
539 set_immediate_dominator (loops
->cfg
.dom
, succ_bb
, switch_bb
);
541 /* Compute new loop. */
542 add_loop (loops
, loop
);
543 flow_loop_tree_node_add (outer
, loop
);
545 /* Add switch_bb to appropriate loop. */
546 add_bb_to_loop (switch_bb
, outer
);
548 /* Fix frequencies. */
549 switch_bb
->frequency
= freq
;
550 switch_bb
->count
= cnt
;
551 for (e
= switch_bb
->succ
; e
; e
= e
->succ_next
)
552 e
->count
= (switch_bb
->count
* e
->probability
) / REG_BR_PROB_BASE
;
553 scale_loop_frequencies (loop
, prob
, tot_prob
);
554 scale_loop_frequencies (succ_bb
->loop_father
, tot_prob
- prob
, tot_prob
);
556 /* Update dominators of blocks outside of LOOP. */
557 dom_bbs
= xcalloc (n_basic_blocks
, sizeof (basic_block
));
559 seen
= sbitmap_alloc (last_basic_block
);
561 body
= get_loop_body (loop
);
563 for (i
= 0; i
< loop
->num_nodes
; i
++)
564 SET_BIT (seen
, body
[i
]->index
);
566 for (i
= 0; i
< loop
->num_nodes
; i
++)
571 nldom
= get_dominated_by (loops
->cfg
.dom
, body
[i
], &ldom
);
572 for (j
= 0; j
< nldom
; j
++)
573 if (!TEST_BIT (seen
, ldom
[j
]->index
))
575 SET_BIT (seen
, ldom
[j
]->index
);
576 dom_bbs
[n_dom_bbs
++] = ldom
[j
];
581 iterate_fix_dominators (loops
->cfg
.dom
, dom_bbs
, n_dom_bbs
);
590 /* Remove the latch edge of a LOOP and update LOOPS tree to indicate that
591 the LOOP was removed. After this function, original loop latch will
592 have no successor, which caller is expected to fix somehow. */
594 unloop (struct loops
*loops
, struct loop
*loop
)
599 basic_block latch
= loop
->latch
;
603 /* This is relatively straightforward. The dominators are unchanged, as
604 loop header dominates loop latch, so the only thing we have to care of
605 is the placement of loops and basic blocks inside the loop tree. We
606 move them all to the loop->outer, and then let fix_bb_placements do
609 body
= get_loop_body (loop
);
610 edges
= get_loop_exit_edges (loop
, &n_edges
);
612 for (i
= 0; i
< n
; i
++)
613 if (body
[i
]->loop_father
== loop
)
615 remove_bb_from_loops (body
[i
]);
616 add_bb_to_loop (body
[i
], loop
->outer
);
623 flow_loop_tree_node_remove (ploop
);
624 flow_loop_tree_node_add (loop
->outer
, ploop
);
627 /* Remove the loop and free its data. */
628 flow_loop_tree_node_remove (loop
);
629 loops
->parray
[loop
->num
] = NULL
;
630 flow_loop_free (loop
);
632 remove_edge (latch
->succ
);
633 fix_bb_placements (loops
, latch
);
635 /* If the loop was inside an irreducible region, we would have to somehow
636 update the irreducible marks inside its body. While it is certainly
637 possible to do, it is a bit complicated and this situation should be
638 very rare, so we just remark all loops in this case. */
639 for (i
= 0; i
< n_edges
; i
++)
640 if (edges
[i
]->flags
& EDGE_IRREDUCIBLE_LOOP
)
643 mark_irreducible_loops (loops
);
647 /* Fix placement of LOOP inside loop tree, i.e. find the innermost superloop
648 FATHER of LOOP such that all of the edges coming out of LOOP belong to
649 FATHER, and set it as outer loop of LOOP. Return 1 if placement of
652 fix_loop_placement (struct loop
*loop
)
657 struct loop
*father
= loop
->pred
[0], *act
;
659 body
= get_loop_body (loop
);
660 for (i
= 0; i
< loop
->num_nodes
; i
++)
661 for (e
= body
[i
]->succ
; e
; e
= e
->succ_next
)
662 if (!flow_bb_inside_loop_p (loop
, e
->dest
))
664 act
= find_common_loop (loop
, e
->dest
->loop_father
);
665 if (flow_loop_nested_p (father
, act
))
670 if (father
!= loop
->outer
)
672 for (act
= loop
->outer
; act
!= father
; act
= act
->outer
)
673 act
->num_nodes
-= loop
->num_nodes
;
674 flow_loop_tree_node_remove (loop
);
675 flow_loop_tree_node_add (father
, loop
);
681 /* Fix placement of superloops of LOOP inside loop tree, i.e. ensure that
682 condition stated in description of fix_loop_placement holds for them.
683 It is used in case when we removed some edges coming out of LOOP, which
684 may cause the right placement of LOOP inside loop tree to change. */
686 fix_loop_placements (struct loop
*loop
)
693 if (!fix_loop_placement (loop
))
699 /* Creates place for a new LOOP in LOOPS structure. */
701 place_new_loop (struct loops
*loops
, struct loop
*loop
)
704 xrealloc (loops
->parray
, (loops
->num
+ 1) * sizeof (struct loop
*));
705 loops
->parray
[loops
->num
] = loop
;
707 loop
->num
= loops
->num
++;
710 /* Copies copy of LOOP as subloop of TARGET loop, placing newly
711 created loop into LOOPS structure. */
713 duplicate_loop (struct loops
*loops
, struct loop
*loop
, struct loop
*target
)
716 cloop
= xcalloc (1, sizeof (struct loop
));
717 place_new_loop (loops
, cloop
);
719 /* Initialize copied loop. */
720 cloop
->level
= loop
->level
;
722 /* Set it as copy of loop. */
725 /* Add it to target. */
726 flow_loop_tree_node_add (target
, cloop
);
731 /* Copies structure of subloops of LOOP into TARGET loop, placing
732 newly created loops into loop tree stored in LOOPS. */
734 duplicate_subloops (struct loops
*loops
, struct loop
*loop
, struct loop
*target
)
736 struct loop
*aloop
, *cloop
;
738 for (aloop
= loop
->inner
; aloop
; aloop
= aloop
->next
)
740 cloop
= duplicate_loop (loops
, aloop
, target
);
741 duplicate_subloops (loops
, aloop
, cloop
);
745 /* Copies structure of subloops of N loops, stored in array COPIED_LOOPS,
746 into TARGET loop, placing newly created loops into loop tree LOOPS. */
748 copy_loops_to (struct loops
*loops
, struct loop
**copied_loops
, int n
, struct loop
*target
)
753 for (i
= 0; i
< n
; i
++)
755 aloop
= duplicate_loop (loops
, copied_loops
[i
], target
);
756 duplicate_subloops (loops
, copied_loops
[i
], aloop
);
760 /* Redirects edge E to basic block DEST. */
762 loop_redirect_edge (edge e
, basic_block dest
)
767 redirect_edge_and_branch_force (e
, dest
);
770 /* Deletes edge E from a branch if possible. Unless REALLY_DELETE is set,
771 just test whether it is possible to remove the edge. */
773 loop_delete_branch_edge (edge e
, int really_delete
)
775 basic_block src
= e
->src
;
779 if (src
->succ
->succ_next
)
783 /* Cannot handle more than two exit edges. */
784 if (src
->succ
->succ_next
->succ_next
)
786 /* And it must be just a simple branch. */
787 if (!any_condjump_p (src
->end
))
790 snd
= e
== src
->succ
? src
->succ
->succ_next
: src
->succ
;
792 if (newdest
== EXIT_BLOCK_PTR
)
795 /* Hopefully the above conditions should suffice. */
799 /* Redirecting behaves wrongly wrto this flag. */
800 irr
= snd
->flags
& EDGE_IRREDUCIBLE_LOOP
;
802 if (!redirect_edge_and_branch (e
, newdest
))
804 src
->succ
->flags
&= ~EDGE_IRREDUCIBLE_LOOP
;
805 src
->succ
->flags
|= irr
;
811 /* Cannot happen -- we are using this only to remove an edge
816 return false; /* To avoid warning, cannot get here. */
819 /* Check whether LOOP's body can be duplicated. */
821 can_duplicate_loop_p (struct loop
*loop
)
824 basic_block
*bbs
= get_loop_body (loop
);
826 ret
= can_copy_bbs_p (bbs
, loop
->num_nodes
);
832 #define RDIV(X,Y) (((X) + (Y) / 2) / (Y))
834 /* Duplicates body of LOOP to given edge E NDUPL times. Takes care of updating
835 LOOPS structure and dominators. E's destination must be LOOP header for
836 this to work, i.e. it must be entry or latch edge of this loop; these are
837 unique, as the loops must have preheaders for this function to work
838 correctly (in case E is latch, the function unrolls the loop, if E is entry
839 edge, it peels the loop). Store edges created by copying ORIG edge from
840 copies corresponding to set bits in WONT_EXIT bitmap (bit 0 corresponds to
841 original LOOP body, the other copies are numbered in order given by control
842 flow through them) into TO_REMOVE array. Returns false if duplication is
845 duplicate_loop_to_header_edge (struct loop
*loop
, edge e
, struct loops
*loops
,
846 unsigned int ndupl
, sbitmap wont_exit
,
847 edge orig
, edge
*to_remove
,
848 unsigned int *n_to_remove
, int flags
)
850 struct loop
*target
, *aloop
;
851 struct loop
**orig_loops
;
852 unsigned n_orig_loops
;
853 basic_block header
= loop
->header
, latch
= loop
->latch
;
854 basic_block
*new_bbs
, *bbs
, *first_active
;
855 basic_block new_bb
, bb
, first_active_latch
= NULL
;
857 edge spec_edges
[2], new_spec_edges
[2];
861 int is_latch
= (latch
== e
->src
);
862 int scale_act
= 0, *scale_step
= NULL
, scale_main
= 0;
863 int p
, freq_in
, freq_le
, freq_out_orig
;
864 int prob_pass_thru
, prob_pass_wont_exit
, prob_pass_main
;
865 int add_irreducible_flag
;
867 if (e
->dest
!= loop
->header
)
874 /* Orig must be edge out of the loop. */
875 if (!flow_bb_inside_loop_p (loop
, orig
->src
))
877 if (flow_bb_inside_loop_p (loop
, orig
->dest
))
881 bbs
= get_loop_body (loop
);
883 /* Check whether duplication is possible. */
884 if (!can_copy_bbs_p (bbs
, loop
->num_nodes
))
889 new_bbs
= xmalloc (sizeof (basic_block
) * loop
->num_nodes
);
891 /* In case we are doing loop peeling and the loop is in the middle of
892 irreducible region, the peeled copies will be inside it too. */
893 add_irreducible_flag
= e
->flags
& EDGE_IRREDUCIBLE_LOOP
;
894 if (is_latch
&& add_irreducible_flag
)
897 /* Find edge from latch. */
898 latch_edge
= loop_latch_edge (loop
);
900 if (flags
& DLTHE_FLAG_UPDATE_FREQ
)
902 /* Calculate coefficients by that we have to scale frequencies
903 of duplicated loop bodies. */
904 freq_in
= header
->frequency
;
905 freq_le
= EDGE_FREQUENCY (latch_edge
);
908 if (freq_in
< freq_le
)
910 freq_out_orig
= orig
? EDGE_FREQUENCY (orig
) : freq_in
- freq_le
;
911 if (freq_out_orig
> freq_in
- freq_le
)
912 freq_out_orig
= freq_in
- freq_le
;
913 prob_pass_thru
= RDIV (REG_BR_PROB_BASE
* freq_le
, freq_in
);
914 prob_pass_wont_exit
=
915 RDIV (REG_BR_PROB_BASE
* (freq_le
+ freq_out_orig
), freq_in
);
917 scale_step
= xmalloc (ndupl
* sizeof (int));
919 for (i
= 1; i
<= ndupl
; i
++)
920 scale_step
[i
- 1] = TEST_BIT (wont_exit
, i
)
921 ? prob_pass_wont_exit
926 prob_pass_main
= TEST_BIT (wont_exit
, 0)
927 ? prob_pass_wont_exit
930 scale_main
= REG_BR_PROB_BASE
;
931 for (i
= 0; i
< ndupl
; i
++)
934 p
= RDIV (p
* scale_step
[i
], REG_BR_PROB_BASE
);
936 scale_main
= RDIV (REG_BR_PROB_BASE
* REG_BR_PROB_BASE
, scale_main
);
937 scale_act
= RDIV (scale_main
* prob_pass_main
, REG_BR_PROB_BASE
);
941 scale_main
= REG_BR_PROB_BASE
;
942 for (i
= 0; i
< ndupl
; i
++)
943 scale_main
= RDIV (scale_main
* scale_step
[i
], REG_BR_PROB_BASE
);
944 scale_act
= REG_BR_PROB_BASE
- prob_pass_thru
;
946 for (i
= 0; i
< ndupl
; i
++)
947 if (scale_step
[i
] < 0 || scale_step
[i
] > REG_BR_PROB_BASE
)
949 if (scale_main
< 0 || scale_main
> REG_BR_PROB_BASE
950 || scale_act
< 0 || scale_act
> REG_BR_PROB_BASE
)
954 /* Loop the new bbs will belong to. */
955 target
= e
->src
->loop_father
;
957 /* Original loops. */
959 for (aloop
= loop
->inner
; aloop
; aloop
= aloop
->next
)
961 orig_loops
= xcalloc (n_orig_loops
, sizeof (struct loop
*));
962 for (aloop
= loop
->inner
, i
= 0; aloop
; aloop
= aloop
->next
, i
++)
963 orig_loops
[i
] = aloop
;
969 first_active
= xmalloc (n
* sizeof (basic_block
));
972 memcpy (first_active
, bbs
, n
* sizeof (basic_block
));
973 first_active_latch
= latch
;
976 /* Record exit edge in original loop body. */
977 if (orig
&& TEST_BIT (wont_exit
, 0))
978 to_remove
[(*n_to_remove
)++] = orig
;
980 spec_edges
[SE_ORIG
] = orig
;
981 spec_edges
[SE_LATCH
] = latch_edge
;
983 for (j
= 0; j
< ndupl
; j
++)
986 copy_loops_to (loops
, orig_loops
, n_orig_loops
, target
);
989 copy_bbs (bbs
, n
, new_bbs
, spec_edges
, 2, new_spec_edges
, loop
, loops
);
991 /* Note whether the blocks and edges belong to an irreducible loop. */
992 if (add_irreducible_flag
)
994 for (i
= 0; i
< n
; i
++)
995 new_bbs
[i
]->rbi
->duplicated
= 1;
996 for (i
= 0; i
< n
; i
++)
999 if (new_bb
->loop_father
== target
)
1000 new_bb
->flags
|= BB_IRREDUCIBLE_LOOP
;
1002 for (ae
= new_bb
->succ
; ae
; ae
= ae
->succ_next
)
1003 if (ae
->dest
->rbi
->duplicated
1004 && (ae
->src
->loop_father
== target
1005 || ae
->dest
->loop_father
== target
))
1006 ae
->flags
|= EDGE_IRREDUCIBLE_LOOP
;
1008 for (i
= 0; i
< n
; i
++)
1009 new_bbs
[i
]->rbi
->duplicated
= 0;
1012 /* Redirect the special edges. */
1015 redirect_edge_and_branch_force (latch_edge
, new_bbs
[0]);
1016 redirect_edge_and_branch_force (new_spec_edges
[SE_LATCH
],
1018 set_immediate_dominator (loops
->cfg
.dom
, new_bbs
[0], latch
);
1019 latch
= loop
->latch
= new_bbs
[1];
1020 e
= latch_edge
= new_spec_edges
[SE_LATCH
];
1024 redirect_edge_and_branch_force (new_spec_edges
[SE_LATCH
],
1026 redirect_edge_and_branch_force (e
, new_bbs
[0]);
1027 set_immediate_dominator (loops
->cfg
.dom
, new_bbs
[0], e
->src
);
1028 e
= new_spec_edges
[SE_LATCH
];
1031 /* Record exit edge in this copy. */
1032 if (orig
&& TEST_BIT (wont_exit
, j
+ 1))
1033 to_remove
[(*n_to_remove
)++] = new_spec_edges
[SE_ORIG
];
1035 /* Record the first copy in the control flow order if it is not
1036 the original loop (i.e. in case of peeling). */
1037 if (!first_active_latch
)
1039 memcpy (first_active
, new_bbs
, n
* sizeof (basic_block
));
1040 first_active_latch
= new_bbs
[1];
1043 /* Set counts and frequencies. */
1044 if (flags
& DLTHE_FLAG_UPDATE_FREQ
)
1046 scale_bbs_frequencies (new_bbs
, n
, scale_act
, REG_BR_PROB_BASE
);
1047 scale_act
= RDIV (scale_act
* scale_step
[j
], REG_BR_PROB_BASE
);
1053 /* Update the original loop. */
1055 set_immediate_dominator (loops
->cfg
.dom
, e
->dest
, e
->src
);
1056 if (flags
& DLTHE_FLAG_UPDATE_FREQ
)
1058 scale_bbs_frequencies (bbs
, n
, scale_main
, REG_BR_PROB_BASE
);
1062 /* Update dominators of outer blocks if affected. */
1063 for (i
= 0; i
< n
; i
++)
1065 basic_block dominated
, dom_bb
, *dom_bbs
;
1069 n_dom_bbs
= get_dominated_by (loops
->cfg
.dom
, bb
, &dom_bbs
);
1070 for (j
= 0; j
< n_dom_bbs
; j
++)
1072 dominated
= dom_bbs
[j
];
1073 if (flow_bb_inside_loop_p (loop
, dominated
))
1075 dom_bb
= nearest_common_dominator (
1076 loops
->cfg
.dom
, first_active
[i
], first_active_latch
);
1077 set_immediate_dominator (loops
->cfg
.dom
, dominated
, dom_bb
);
1081 free (first_active
);
1088 /* Creates a pre-header for a LOOP. Returns newly created block. Unless
1089 CP_SIMPLE_PREHEADERS is set in FLAGS, we only force LOOP to have single
1090 entry; otherwise we also force preheader block to have only one successor.
1091 The function also updates dominators stored in DOM. */
1093 create_preheader (struct loop
*loop
, dominance_info dom
, int flags
)
1097 basic_block jump
, src
= 0;
1098 struct loop
*cloop
, *ploop
;
1102 cloop
= loop
->outer
;
1104 for (e
= loop
->header
->pred
; e
; e
= e
->pred_next
)
1106 if (e
->src
== loop
->latch
)
1114 for (e
= loop
->header
->pred
; e
->src
== loop
->latch
; e
= e
->pred_next
);
1115 if (!(flags
& CP_SIMPLE_PREHEADERS
)
1116 || !e
->src
->succ
->succ_next
)
1120 insn
= first_insn_after_basic_block_note (loop
->header
);
1122 insn
= PREV_INSN (insn
);
1124 insn
= get_last_insn ();
1125 if (insn
== loop
->header
->end
)
1127 /* Split_block would not split block after its end. */
1128 emit_note_after (NOTE_INSN_DELETED
, insn
);
1130 fallthru
= split_block (loop
->header
, insn
);
1131 dummy
= fallthru
->src
;
1132 loop
->header
= fallthru
->dest
;
1134 /* The header could be a latch of some superloop(s); due to design of
1135 split_block, it would now move to fallthru->dest. */
1136 for (ploop
= loop
; ploop
; ploop
= ploop
->outer
)
1137 if (ploop
->latch
== dummy
)
1138 ploop
->latch
= fallthru
->dest
;
1140 add_to_dominance_info (dom
, fallthru
->dest
);
1142 /* Redirect edges. */
1143 for (e
= dummy
->pred
; e
; e
= e
->pred_next
)
1146 if (src
== loop
->latch
)
1152 dummy
->frequency
-= EDGE_FREQUENCY (e
);
1153 dummy
->count
-= e
->count
;
1154 fallthru
->count
-= e
->count
;
1155 jump
= redirect_edge_and_branch_force (e
, loop
->header
);
1158 add_to_dominance_info (dom
, jump
);
1159 set_immediate_dominator (dom
, jump
, src
);
1160 add_bb_to_loop (jump
, loop
);
1164 /* Update structures. */
1165 redirect_immediate_dominators (dom
, dummy
, loop
->header
);
1166 set_immediate_dominator (dom
, loop
->header
, dummy
);
1167 loop
->header
->loop_father
= loop
;
1168 add_bb_to_loop (dummy
, cloop
);
1170 fprintf (rtl_dump_file
, "Created preheader block for loop %i\n",
1176 /* Create preheaders for each loop from loop tree stored in LOOPS; for meaning
1177 of FLAGS see create_preheader. */
1179 create_preheaders (struct loops
*loops
, int flags
)
1182 for (i
= 1; i
< loops
->num
; i
++)
1183 create_preheader (loops
->parray
[i
], loops
->cfg
.dom
, flags
);
1184 loops
->state
|= LOOPS_HAVE_PREHEADERS
;
1187 /* Forces all loop latches of loops from loop tree LOOPS to have only single
1190 force_single_succ_latches (struct loops
*loops
)
1196 for (i
= 1; i
< loops
->num
; i
++)
1198 loop
= loops
->parray
[i
];
1199 if (loop
->latch
!= loop
->header
1200 && !loop
->latch
->succ
->succ_next
)
1203 for (e
= loop
->header
->pred
; e
->src
!= loop
->latch
; e
= e
->pred_next
)
1206 loop_split_edge_with (e
, NULL_RTX
, loops
);
1208 loops
->state
|= LOOPS_HAVE_SIMPLE_LATCHES
;
1211 /* A quite stupid function to put INSNS on edge E. They are supposed to form
1212 just one basic block. Jumps in INSNS are not handled, so cfg do not have to
1213 be ok after this function. The created block is placed on correct place
1214 in LOOPS structure and its dominator is set. */
1216 loop_split_edge_with (edge e
, rtx insns
, struct loops
*loops
)
1218 basic_block src
, dest
, new_bb
;
1219 struct loop
*loop_c
;
1225 loop_c
= find_common_loop (src
->loop_father
, dest
->loop_father
);
1227 /* Create basic block for it. */
1229 new_bb
= split_edge (e
);
1230 add_to_dominance_info (loops
->cfg
.dom
, new_bb
);
1231 add_bb_to_loop (new_bb
, loop_c
);
1232 new_bb
->flags
= insns
? BB_SUPERBLOCK
: 0;
1234 new_e
= new_bb
->succ
;
1235 if (e
->flags
& EDGE_IRREDUCIBLE_LOOP
)
1237 new_bb
->flags
|= BB_IRREDUCIBLE_LOOP
;
1238 new_e
->flags
|= EDGE_IRREDUCIBLE_LOOP
;
1242 emit_insn_after (insns
, new_bb
->end
);
1244 set_immediate_dominator (loops
->cfg
.dom
, new_bb
, src
);
1245 set_immediate_dominator (loops
->cfg
.dom
, dest
,
1246 recount_dominator (loops
->cfg
.dom
, dest
));
1248 if (dest
->loop_father
->latch
== src
)
1249 dest
->loop_father
->latch
= new_bb
;