1 /* Loop manipulation code for GNU compiler.
2 Copyright (C) 2002, 2003, 2004, 2005 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, 51 Franklin Street, Fifth Floor, Boston, MA
23 #include "coretypes.h"
26 #include "hard-reg-set.h"
28 #include "basic-block.h"
30 #include "cfglayout.h"
34 static void duplicate_subloops (struct loop
*, struct loop
*);
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 (basic_block
, 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 basic_block
create_preheader (struct loop
*, int);
45 static void unloop (struct loop
*, bool *);
47 #define RDIV(X,Y) (((X) + (Y) / 2) / (Y))
49 /* Checks whether basic block BB is dominated by DATA. */
51 rpe_enum_p (basic_block bb
, void *data
)
53 return dominated_by_p (CDI_DOMINATORS
, bb
, data
);
56 /* Remove basic blocks BBS. NBBS is the number of the basic blocks. */
59 remove_bbs (basic_block
*bbs
, int nbbs
)
63 for (i
= 0; i
< nbbs
; i
++)
64 delete_basic_block (bbs
[i
]);
67 /* Find path -- i.e. the basic blocks dominated by edge E and put them
68 into array BBS, that will be allocated large enough to contain them.
69 E->dest must have exactly one predecessor for this to work (it is
70 easy to achieve and we do not put it here because we do not want to
71 alter anything by this function). The number of basic blocks in the
74 find_path (edge e
, basic_block
**bbs
)
76 gcc_assert (EDGE_COUNT (e
->dest
->preds
) <= 1);
78 /* Find bbs in the path. */
79 *bbs
= XCNEWVEC (basic_block
, n_basic_blocks
);
80 return dfs_enumerate_from (e
->dest
, 0, rpe_enum_p
, *bbs
,
81 n_basic_blocks
, e
->dest
);
84 /* Fix placement of basic block BB inside loop hierarchy --
85 Let L be a loop to that BB belongs. Then every successor of BB must either
86 1) belong to some superloop of loop L, or
87 2) be a header of loop K such that K->outer is superloop of L
88 Returns true if we had to move BB into other loop to enforce this condition,
89 false if the placement of BB was already correct (provided that placements
90 of its successors are correct). */
92 fix_bb_placement (basic_block bb
)
96 struct loop
*loop
= current_loops
->tree_root
, *act
;
98 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
100 if (e
->dest
== EXIT_BLOCK_PTR
)
103 act
= e
->dest
->loop_father
;
104 if (act
->header
== e
->dest
)
107 if (flow_loop_nested_p (loop
, act
))
111 if (loop
== bb
->loop_father
)
114 remove_bb_from_loops (bb
);
115 add_bb_to_loop (bb
, loop
);
120 /* Fix placement of LOOP inside loop tree, i.e. find the innermost superloop
121 of LOOP to that leads at least one exit edge of LOOP, and set it
122 as the immediate superloop of LOOP. Return true if the immediate superloop
126 fix_loop_placement (struct loop
*loop
)
130 VEC (edge
, heap
) *exits
= get_loop_exit_edges (loop
);
131 struct loop
*father
= current_loops
->tree_root
, *act
;
134 for (i
= 0; VEC_iterate (edge
, exits
, i
, e
); i
++)
136 act
= find_common_loop (loop
, e
->dest
->loop_father
);
137 if (flow_loop_nested_p (father
, act
))
141 if (father
!= loop
->outer
)
143 for (act
= loop
->outer
; act
!= father
; act
= act
->outer
)
144 act
->num_nodes
-= loop
->num_nodes
;
145 flow_loop_tree_node_remove (loop
);
146 flow_loop_tree_node_add (father
, loop
);
148 /* The exit edges of LOOP no longer exits its original immediate
149 superloops; remove them from the appropriate exit lists. */
150 for (i
= 0; VEC_iterate (edge
, exits
, i
, e
); i
++)
151 rescan_loop_exit (e
, false, false);
156 VEC_free (edge
, heap
, exits
);
160 /* Fix placements of basic blocks inside loop hierarchy stored in loops; i.e.
161 enforce condition condition stated in description of fix_bb_placement. We
162 start from basic block FROM that had some of its successors removed, so that
163 his placement no longer has to be correct, and iteratively fix placement of
164 its predecessors that may change if placement of FROM changed. Also fix
165 placement of subloops of FROM->loop_father, that might also be altered due
166 to this change; the condition for them is similar, except that instead of
167 successors we consider edges coming out of the loops.
169 If the changes may invalidate the information about irreducible regions,
170 IRRED_INVALIDATED is set to true. */
173 fix_bb_placements (basic_block from
,
174 bool *irred_invalidated
)
177 basic_block
*queue
, *qtop
, *qbeg
, *qend
;
178 struct loop
*base_loop
;
181 /* We pass through blocks back-reachable from FROM, testing whether some
182 of their successors moved to outer loop. It may be necessary to
183 iterate several times, but it is finite, as we stop unless we move
184 the basic block up the loop structure. The whole story is a bit
185 more complicated due to presence of subloops, those are moved using
186 fix_loop_placement. */
188 base_loop
= from
->loop_father
;
189 if (base_loop
== current_loops
->tree_root
)
192 in_queue
= sbitmap_alloc (last_basic_block
);
193 sbitmap_zero (in_queue
);
194 SET_BIT (in_queue
, from
->index
);
195 /* Prevent us from going out of the base_loop. */
196 SET_BIT (in_queue
, base_loop
->header
->index
);
198 queue
= XNEWVEC (basic_block
, base_loop
->num_nodes
+ 1);
199 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 (from
))
226 FOR_EACH_EDGE (e
, ei
, from
->succs
)
228 if (e
->flags
& EDGE_IRREDUCIBLE_LOOP
)
229 *irred_invalidated
= true;
232 /* Something has changed, insert predecessors into queue. */
233 FOR_EACH_EDGE (e
, ei
, from
->preds
)
235 basic_block pred
= e
->src
;
238 if (e
->flags
& EDGE_IRREDUCIBLE_LOOP
)
239 *irred_invalidated
= true;
241 if (TEST_BIT (in_queue
, pred
->index
))
244 /* If it is subloop, then it either was not moved, or
245 the path up the loop tree from base_loop do not contain
247 nca
= find_common_loop (pred
->loop_father
, base_loop
);
248 if (pred
->loop_father
!= base_loop
250 || nca
!= pred
->loop_father
))
251 pred
= pred
->loop_father
->header
;
252 else if (!flow_loop_nested_p (from
->loop_father
, pred
->loop_father
))
254 /* No point in processing it. */
258 if (TEST_BIT (in_queue
, pred
->index
))
261 /* Schedule the basic block. */
266 SET_BIT (in_queue
, pred
->index
);
273 /* Removes path beginning at edge E, i.e. remove basic blocks dominated by E
274 and update loop structures and dominators. Return true if we were able
275 to remove the path, false otherwise (and nothing is affected then). */
280 basic_block
*rem_bbs
, *bord_bbs
, *dom_bbs
, from
, bb
;
281 int i
, nrem
, n_bord_bbs
, n_dom_bbs
, nreml
;
283 bool irred_invalidated
= false;
284 struct loop
**deleted_loop
;
286 if (!can_remove_branch_p (e
))
289 /* Keep track of whether we need to update information about irreducible
290 regions. This is the case if the removed area is a part of the
291 irreducible region, or if the set of basic blocks that belong to a loop
292 that is inside an irreducible region is changed, or if such a loop is
294 if (e
->flags
& EDGE_IRREDUCIBLE_LOOP
)
295 irred_invalidated
= true;
297 /* We need to check whether basic blocks are dominated by the edge
298 e, but we only have basic block dominators. This is easy to
299 fix -- when e->dest has exactly one predecessor, this corresponds
300 to blocks dominated by e->dest, if not, split the edge. */
301 if (!single_pred_p (e
->dest
))
302 e
= single_pred_edge (split_edge (e
));
304 /* It may happen that by removing path we remove one or more loops
305 we belong to. In this case first unloop the loops, then proceed
306 normally. We may assume that e->dest is not a header of any loop,
307 as it now has exactly one predecessor. */
308 while (e
->src
->loop_father
->outer
309 && dominated_by_p (CDI_DOMINATORS
,
310 e
->src
->loop_father
->latch
, e
->dest
))
311 unloop (e
->src
->loop_father
, &irred_invalidated
);
313 /* Identify the path. */
314 nrem
= find_path (e
, &rem_bbs
);
317 bord_bbs
= XCNEWVEC (basic_block
, n_basic_blocks
);
318 seen
= sbitmap_alloc (last_basic_block
);
321 /* Find "border" hexes -- i.e. those with predecessor in removed path. */
322 for (i
= 0; i
< nrem
; i
++)
323 SET_BIT (seen
, rem_bbs
[i
]->index
);
324 for (i
= 0; i
< nrem
; i
++)
328 FOR_EACH_EDGE (ae
, ei
, rem_bbs
[i
]->succs
)
329 if (ae
->dest
!= EXIT_BLOCK_PTR
&& !TEST_BIT (seen
, ae
->dest
->index
))
331 SET_BIT (seen
, ae
->dest
->index
);
332 bord_bbs
[n_bord_bbs
++] = ae
->dest
;
334 if (ae
->flags
& EDGE_IRREDUCIBLE_LOOP
)
335 irred_invalidated
= true;
339 /* Remove the path. */
342 dom_bbs
= XCNEWVEC (basic_block
, n_basic_blocks
);
344 /* Cancel loops contained in the path. */
345 deleted_loop
= XNEWVEC (struct loop
*, nrem
);
347 for (i
= 0; i
< nrem
; i
++)
348 if (rem_bbs
[i
]->loop_father
->header
== rem_bbs
[i
])
349 deleted_loop
[nreml
++] = rem_bbs
[i
]->loop_father
;
351 remove_bbs (rem_bbs
, nrem
);
354 for (i
= 0; i
< nreml
; i
++)
355 cancel_loop_tree (deleted_loop
[i
]);
358 /* Find blocks whose dominators may be affected. */
361 for (i
= 0; i
< n_bord_bbs
; i
++)
365 bb
= get_immediate_dominator (CDI_DOMINATORS
, bord_bbs
[i
]);
366 if (TEST_BIT (seen
, bb
->index
))
368 SET_BIT (seen
, bb
->index
);
370 for (ldom
= first_dom_son (CDI_DOMINATORS
, bb
);
372 ldom
= next_dom_son (CDI_DOMINATORS
, ldom
))
373 if (!dominated_by_p (CDI_DOMINATORS
, from
, ldom
))
374 dom_bbs
[n_dom_bbs
++] = ldom
;
379 /* Recount dominators. */
380 iterate_fix_dominators (CDI_DOMINATORS
, dom_bbs
, n_dom_bbs
);
384 /* Fix placements of basic blocks inside loops and the placement of
385 loops in the loop tree. */
386 fix_bb_placements (from
, &irred_invalidated
);
387 fix_loop_placements (from
->loop_father
, &irred_invalidated
);
389 if (irred_invalidated
390 && (current_loops
->state
& LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS
) != 0)
391 mark_irreducible_loops ();
396 /* Creates place for a new LOOP in loops structure. */
399 place_new_loop (struct loop
*loop
)
401 loop
->num
= number_of_loops ();
402 VEC_safe_push (loop_p
, heap
, current_loops
->larray
, loop
);
405 /* Given LOOP structure with filled header and latch, find the body of the
406 corresponding loop and add it to loops tree. Insert the LOOP as a son of
410 add_loop (struct loop
*loop
, struct loop
*outer
)
414 struct loop
*subloop
;
416 /* Add it to loop structure. */
417 place_new_loop (loop
);
418 flow_loop_tree_node_add (outer
, loop
);
420 /* Find its nodes. */
421 bbs
= XNEWVEC (basic_block
, n_basic_blocks
);
422 n
= get_loop_body_with_size (loop
, bbs
, n_basic_blocks
);
424 for (i
= 0; i
< n
; i
++)
426 if (bbs
[i
]->loop_father
== outer
)
428 remove_bb_from_loops (bbs
[i
]);
429 add_bb_to_loop (bbs
[i
], loop
);
435 /* If we find a direct subloop of OUTER, move it to LOOP. */
436 subloop
= bbs
[i
]->loop_father
;
437 if (subloop
->outer
== outer
438 && subloop
->header
== bbs
[i
])
440 flow_loop_tree_node_remove (subloop
);
441 flow_loop_tree_node_add (loop
, subloop
);
448 /* Multiply all frequencies in LOOP by NUM/DEN. */
450 scale_loop_frequencies (struct loop
*loop
, int num
, int den
)
454 bbs
= get_loop_body (loop
);
455 scale_bbs_frequencies_int (bbs
, loop
->num_nodes
, num
, den
);
459 /* Make area between HEADER_EDGE and LATCH_EDGE a loop by connecting
460 latch to header and update loop tree and dominators
461 accordingly. Everything between them plus LATCH_EDGE destination must
462 be dominated by HEADER_EDGE destination, and back-reachable from
463 LATCH_EDGE source. HEADER_EDGE is redirected to basic block SWITCH_BB,
464 FALSE_EDGE of SWITCH_BB to original destination of HEADER_EDGE and
465 TRUE_EDGE of SWITCH_BB to original destination of LATCH_EDGE.
466 Returns the newly created loop. Frequencies and counts in the new loop
467 are scaled by FALSE_SCALE and in the old one by TRUE_SCALE. */
470 loopify (edge latch_edge
, edge header_edge
,
471 basic_block switch_bb
, edge true_edge
, edge false_edge
,
472 bool redirect_all_edges
, unsigned true_scale
, unsigned false_scale
)
474 basic_block succ_bb
= latch_edge
->dest
;
475 basic_block pred_bb
= header_edge
->src
;
476 basic_block
*dom_bbs
, *body
;
477 unsigned n_dom_bbs
, i
;
479 struct loop
*loop
= alloc_loop ();
480 struct loop
*outer
= succ_bb
->loop_father
->outer
;
486 loop
->header
= header_edge
->dest
;
487 loop
->latch
= latch_edge
->src
;
489 freq
= EDGE_FREQUENCY (header_edge
);
490 cnt
= header_edge
->count
;
492 /* Redirect edges. */
493 loop_redirect_edge (latch_edge
, loop
->header
);
494 loop_redirect_edge (true_edge
, succ_bb
);
496 /* During loop versioning, one of the switch_bb edge is already properly
497 set. Do not redirect it again unless redirect_all_edges is true. */
498 if (redirect_all_edges
)
500 loop_redirect_edge (header_edge
, switch_bb
);
501 loop_redirect_edge (false_edge
, loop
->header
);
503 /* Update dominators. */
504 set_immediate_dominator (CDI_DOMINATORS
, switch_bb
, pred_bb
);
505 set_immediate_dominator (CDI_DOMINATORS
, loop
->header
, switch_bb
);
508 set_immediate_dominator (CDI_DOMINATORS
, succ_bb
, switch_bb
);
510 /* Compute new loop. */
511 add_loop (loop
, outer
);
513 /* Add switch_bb to appropriate loop. */
514 if (switch_bb
->loop_father
)
515 remove_bb_from_loops (switch_bb
);
516 add_bb_to_loop (switch_bb
, outer
);
518 /* Fix frequencies. */
519 if (redirect_all_edges
)
521 switch_bb
->frequency
= freq
;
522 switch_bb
->count
= cnt
;
523 FOR_EACH_EDGE (e
, ei
, switch_bb
->succs
)
525 e
->count
= (switch_bb
->count
* e
->probability
) / REG_BR_PROB_BASE
;
528 scale_loop_frequencies (loop
, false_scale
, REG_BR_PROB_BASE
);
529 scale_loop_frequencies (succ_bb
->loop_father
, true_scale
, REG_BR_PROB_BASE
);
531 /* Update dominators of blocks outside of LOOP. */
532 dom_bbs
= XCNEWVEC (basic_block
, n_basic_blocks
);
534 seen
= sbitmap_alloc (last_basic_block
);
536 body
= get_loop_body (loop
);
538 for (i
= 0; i
< loop
->num_nodes
; i
++)
539 SET_BIT (seen
, body
[i
]->index
);
541 for (i
= 0; i
< loop
->num_nodes
; i
++)
545 for (ldom
= first_dom_son (CDI_DOMINATORS
, body
[i
]);
547 ldom
= next_dom_son (CDI_DOMINATORS
, ldom
))
548 if (!TEST_BIT (seen
, ldom
->index
))
550 SET_BIT (seen
, ldom
->index
);
551 dom_bbs
[n_dom_bbs
++] = ldom
;
555 iterate_fix_dominators (CDI_DOMINATORS
, dom_bbs
, n_dom_bbs
);
564 /* Remove the latch edge of a LOOP and update loops to indicate that
565 the LOOP was removed. After this function, original loop latch will
566 have no successor, which caller is expected to fix somehow.
568 If this may cause the information about irreducible regions to become
569 invalid, IRRED_INVALIDATED is set to true. */
572 unloop (struct loop
*loop
, bool *irred_invalidated
)
577 basic_block latch
= loop
->latch
;
580 if (loop_preheader_edge (loop
)->flags
& EDGE_IRREDUCIBLE_LOOP
)
581 *irred_invalidated
= true;
583 /* This is relatively straightforward. The dominators are unchanged, as
584 loop header dominates loop latch, so the only thing we have to care of
585 is the placement of loops and basic blocks inside the loop tree. We
586 move them all to the loop->outer, and then let fix_bb_placements do
589 body
= get_loop_body (loop
);
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. */
609 remove_edge (single_succ_edge (latch
));
611 /* We do not pass IRRED_INVALIDATED to fix_bb_placements here, as even if
612 there is an irreducible region inside the cancelled loop, the flags will
614 fix_bb_placements (latch
, &dummy
);
617 /* Fix placement of superloops of LOOP inside loop tree, i.e. ensure that
618 condition stated in description of fix_loop_placement holds for them.
619 It is used in case when we removed some edges coming out of LOOP, which
620 may cause the right placement of LOOP inside loop tree to change.
622 IRRED_INVALIDATED is set to true if a change in the loop structures might
623 invalidate the information about irreducible regions. */
626 fix_loop_placements (struct loop
*loop
, bool *irred_invalidated
)
633 if (!fix_loop_placement (loop
))
636 /* Changing the placement of a loop in the loop tree may alter the
637 validity of condition 2) of the description of fix_bb_placement
638 for its preheader, because the successor is the header and belongs
639 to the loop. So call fix_bb_placements to fix up the placement
640 of the preheader and (possibly) of its predecessors. */
641 fix_bb_placements (loop_preheader_edge (loop
)->src
,
647 /* Copies copy of LOOP as subloop of TARGET loop, placing newly
648 created loop into loops structure. */
650 duplicate_loop (struct loop
*loop
, struct loop
*target
)
653 cloop
= alloc_loop ();
654 place_new_loop (cloop
);
656 /* Mark the new loop as copy of LOOP. */
659 /* Add it to target. */
660 flow_loop_tree_node_add (target
, cloop
);
665 /* Copies structure of subloops of LOOP into TARGET loop, placing
666 newly created loops into loop tree. */
668 duplicate_subloops (struct loop
*loop
, struct loop
*target
)
670 struct loop
*aloop
, *cloop
;
672 for (aloop
= loop
->inner
; aloop
; aloop
= aloop
->next
)
674 cloop
= duplicate_loop (aloop
, target
);
675 duplicate_subloops (aloop
, cloop
);
679 /* Copies structure of subloops of N loops, stored in array COPIED_LOOPS,
680 into TARGET loop, placing newly created loops into loop tree. */
682 copy_loops_to (struct loop
**copied_loops
, int n
, struct loop
*target
)
687 for (i
= 0; i
< n
; i
++)
689 aloop
= duplicate_loop (copied_loops
[i
], target
);
690 duplicate_subloops (copied_loops
[i
], aloop
);
694 /* Redirects edge E to basic block DEST. */
696 loop_redirect_edge (edge e
, basic_block dest
)
701 redirect_edge_and_branch_force (e
, dest
);
704 /* Check whether LOOP's body can be duplicated. */
706 can_duplicate_loop_p (struct loop
*loop
)
709 basic_block
*bbs
= get_loop_body (loop
);
711 ret
= can_copy_bbs_p (bbs
, loop
->num_nodes
);
717 /* Sets probability and count of edge E to zero. The probability and count
718 is redistributed evenly to the remaining edges coming from E->src. */
721 set_zero_probability (edge e
)
723 basic_block bb
= e
->src
;
725 edge ae
, last
= NULL
;
726 unsigned n
= EDGE_COUNT (bb
->succs
);
727 gcov_type cnt
= e
->count
, cnt1
;
728 unsigned prob
= e
->probability
, prob1
;
731 cnt1
= cnt
/ (n
- 1);
732 prob1
= prob
/ (n
- 1);
734 FOR_EACH_EDGE (ae
, ei
, bb
->succs
)
739 ae
->probability
+= prob1
;
744 /* Move the rest to one of the edges. */
745 last
->probability
+= prob
% (n
- 1);
746 last
->count
+= cnt
% (n
- 1);
752 /* Duplicates body of LOOP to given edge E NDUPL times. Takes care of updating
753 loop structure and dominators. E's destination must be LOOP header for
754 this to work, i.e. it must be entry or latch edge of this loop; these are
755 unique, as the loops must have preheaders for this function to work
756 correctly (in case E is latch, the function unrolls the loop, if E is entry
757 edge, it peels the loop). Store edges created by copying ORIG edge from
758 copies corresponding to set bits in WONT_EXIT bitmap (bit 0 corresponds to
759 original LOOP body, the other copies are numbered in order given by control
760 flow through them) into TO_REMOVE array. Returns false if duplication is
764 duplicate_loop_to_header_edge (struct loop
*loop
, edge e
,
765 unsigned int ndupl
, sbitmap wont_exit
,
766 edge orig
, VEC (edge
, heap
) **to_remove
,
769 struct loop
*target
, *aloop
;
770 struct loop
**orig_loops
;
771 unsigned n_orig_loops
;
772 basic_block header
= loop
->header
, latch
= loop
->latch
;
773 basic_block
*new_bbs
, *bbs
, *first_active
;
774 basic_block new_bb
, bb
, first_active_latch
= NULL
;
776 edge spec_edges
[2], new_spec_edges
[2];
780 int is_latch
= (latch
== e
->src
);
781 int scale_act
= 0, *scale_step
= NULL
, scale_main
= 0;
782 int scale_after_exit
= 0;
783 int p
, freq_in
, freq_le
, freq_out_orig
;
784 int prob_pass_thru
, prob_pass_wont_exit
, prob_pass_main
;
785 int add_irreducible_flag
;
786 basic_block place_after
;
787 bitmap bbs_to_scale
= NULL
;
790 gcc_assert (e
->dest
== loop
->header
);
791 gcc_assert (ndupl
> 0);
795 /* Orig must be edge out of the loop. */
796 gcc_assert (flow_bb_inside_loop_p (loop
, orig
->src
));
797 gcc_assert (!flow_bb_inside_loop_p (loop
, orig
->dest
));
801 bbs
= get_loop_body_in_dom_order (loop
);
802 gcc_assert (bbs
[0] == loop
->header
);
803 gcc_assert (bbs
[n
- 1] == loop
->latch
);
805 /* Check whether duplication is possible. */
806 if (!can_copy_bbs_p (bbs
, loop
->num_nodes
))
811 new_bbs
= XNEWVEC (basic_block
, loop
->num_nodes
);
813 /* In case we are doing loop peeling and the loop is in the middle of
814 irreducible region, the peeled copies will be inside it too. */
815 add_irreducible_flag
= e
->flags
& EDGE_IRREDUCIBLE_LOOP
;
816 gcc_assert (!is_latch
|| !add_irreducible_flag
);
818 /* Find edge from latch. */
819 latch_edge
= loop_latch_edge (loop
);
821 if (flags
& DLTHE_FLAG_UPDATE_FREQ
)
823 /* Calculate coefficients by that we have to scale frequencies
824 of duplicated loop bodies. */
825 freq_in
= header
->frequency
;
826 freq_le
= EDGE_FREQUENCY (latch_edge
);
829 if (freq_in
< freq_le
)
831 freq_out_orig
= orig
? EDGE_FREQUENCY (orig
) : freq_in
- freq_le
;
832 if (freq_out_orig
> freq_in
- freq_le
)
833 freq_out_orig
= freq_in
- freq_le
;
834 prob_pass_thru
= RDIV (REG_BR_PROB_BASE
* freq_le
, freq_in
);
835 prob_pass_wont_exit
=
836 RDIV (REG_BR_PROB_BASE
* (freq_le
+ freq_out_orig
), freq_in
);
839 && REG_BR_PROB_BASE
- orig
->probability
!= 0)
841 /* The blocks that are dominated by a removed exit edge ORIG have
842 frequencies scaled by this. */
843 scale_after_exit
= RDIV (REG_BR_PROB_BASE
* REG_BR_PROB_BASE
,
844 REG_BR_PROB_BASE
- orig
->probability
);
845 bbs_to_scale
= BITMAP_ALLOC (NULL
);
846 for (i
= 0; i
< n
; i
++)
848 if (bbs
[i
] != orig
->src
849 && dominated_by_p (CDI_DOMINATORS
, bbs
[i
], orig
->src
))
850 bitmap_set_bit (bbs_to_scale
, i
);
854 scale_step
= XNEWVEC (int, ndupl
);
856 for (i
= 1; i
<= ndupl
; i
++)
857 scale_step
[i
- 1] = TEST_BIT (wont_exit
, i
)
858 ? prob_pass_wont_exit
861 /* Complete peeling is special as the probability of exit in last
863 if (flags
& DLTHE_FLAG_COMPLETTE_PEEL
)
865 int wanted_freq
= EDGE_FREQUENCY (e
);
867 if (wanted_freq
> freq_in
)
868 wanted_freq
= freq_in
;
870 gcc_assert (!is_latch
);
871 /* First copy has frequency of incoming edge. Each subsequent
872 frequency should be reduced by prob_pass_wont_exit. Caller
873 should've managed the flags so all except for original loop
874 has won't exist set. */
875 scale_act
= RDIV (wanted_freq
* REG_BR_PROB_BASE
, freq_in
);
876 /* Now simulate the duplication adjustments and compute header
877 frequency of the last copy. */
878 for (i
= 0; i
< ndupl
; i
++)
879 wanted_freq
= RDIV (wanted_freq
* scale_step
[i
], REG_BR_PROB_BASE
);
880 scale_main
= RDIV (wanted_freq
* REG_BR_PROB_BASE
, freq_in
);
884 prob_pass_main
= TEST_BIT (wont_exit
, 0)
885 ? prob_pass_wont_exit
888 scale_main
= REG_BR_PROB_BASE
;
889 for (i
= 0; i
< ndupl
; i
++)
892 p
= RDIV (p
* scale_step
[i
], REG_BR_PROB_BASE
);
894 scale_main
= RDIV (REG_BR_PROB_BASE
* REG_BR_PROB_BASE
, scale_main
);
895 scale_act
= RDIV (scale_main
* prob_pass_main
, REG_BR_PROB_BASE
);
899 scale_main
= REG_BR_PROB_BASE
;
900 for (i
= 0; i
< ndupl
; i
++)
901 scale_main
= RDIV (scale_main
* scale_step
[i
], REG_BR_PROB_BASE
);
902 scale_act
= REG_BR_PROB_BASE
- prob_pass_thru
;
904 for (i
= 0; i
< ndupl
; i
++)
905 gcc_assert (scale_step
[i
] >= 0 && scale_step
[i
] <= REG_BR_PROB_BASE
);
906 gcc_assert (scale_main
>= 0 && scale_main
<= REG_BR_PROB_BASE
907 && scale_act
>= 0 && scale_act
<= REG_BR_PROB_BASE
);
910 /* Loop the new bbs will belong to. */
911 target
= e
->src
->loop_father
;
913 /* Original loops. */
915 for (aloop
= loop
->inner
; aloop
; aloop
= aloop
->next
)
917 orig_loops
= XCNEWVEC (struct loop
*, n_orig_loops
);
918 for (aloop
= loop
->inner
, i
= 0; aloop
; aloop
= aloop
->next
, i
++)
919 orig_loops
[i
] = aloop
;
923 first_active
= XNEWVEC (basic_block
, n
);
926 memcpy (first_active
, bbs
, n
* sizeof (basic_block
));
927 first_active_latch
= latch
;
930 spec_edges
[SE_ORIG
] = orig
;
931 spec_edges
[SE_LATCH
] = latch_edge
;
933 place_after
= e
->src
;
934 for (j
= 0; j
< ndupl
; j
++)
937 copy_loops_to (orig_loops
, n_orig_loops
, target
);
940 copy_bbs (bbs
, n
, new_bbs
, spec_edges
, 2, new_spec_edges
, loop
,
942 place_after
= new_spec_edges
[SE_LATCH
]->src
;
944 if (flags
& DLTHE_RECORD_COPY_NUMBER
)
945 for (i
= 0; i
< n
; i
++)
947 gcc_assert (!new_bbs
[i
]->aux
);
948 new_bbs
[i
]->aux
= (void *)(size_t)(j
+ 1);
951 /* Note whether the blocks and edges belong to an irreducible loop. */
952 if (add_irreducible_flag
)
954 for (i
= 0; i
< n
; i
++)
955 new_bbs
[i
]->flags
|= BB_DUPLICATED
;
956 for (i
= 0; i
< n
; i
++)
960 if (new_bb
->loop_father
== target
)
961 new_bb
->flags
|= BB_IRREDUCIBLE_LOOP
;
963 FOR_EACH_EDGE (ae
, ei
, new_bb
->succs
)
964 if ((ae
->dest
->flags
& BB_DUPLICATED
)
965 && (ae
->src
->loop_father
== target
966 || ae
->dest
->loop_father
== target
))
967 ae
->flags
|= EDGE_IRREDUCIBLE_LOOP
;
969 for (i
= 0; i
< n
; i
++)
970 new_bbs
[i
]->flags
&= ~BB_DUPLICATED
;
973 /* Redirect the special edges. */
976 redirect_edge_and_branch_force (latch_edge
, new_bbs
[0]);
977 redirect_edge_and_branch_force (new_spec_edges
[SE_LATCH
],
979 set_immediate_dominator (CDI_DOMINATORS
, new_bbs
[0], latch
);
980 latch
= loop
->latch
= new_bbs
[n
- 1];
981 e
= latch_edge
= new_spec_edges
[SE_LATCH
];
985 redirect_edge_and_branch_force (new_spec_edges
[SE_LATCH
],
987 redirect_edge_and_branch_force (e
, new_bbs
[0]);
988 set_immediate_dominator (CDI_DOMINATORS
, new_bbs
[0], e
->src
);
989 e
= new_spec_edges
[SE_LATCH
];
992 /* Record exit edge in this copy. */
993 if (orig
&& TEST_BIT (wont_exit
, j
+ 1))
996 VEC_safe_push (edge
, heap
, *to_remove
, new_spec_edges
[SE_ORIG
]);
997 set_zero_probability (new_spec_edges
[SE_ORIG
]);
999 /* Scale the frequencies of the blocks dominated by the exit. */
1002 EXECUTE_IF_SET_IN_BITMAP (bbs_to_scale
, 0, i
, bi
)
1004 scale_bbs_frequencies_int (new_bbs
+ i
, 1, scale_after_exit
,
1010 /* Record the first copy in the control flow order if it is not
1011 the original loop (i.e. in case of peeling). */
1012 if (!first_active_latch
)
1014 memcpy (first_active
, new_bbs
, n
* sizeof (basic_block
));
1015 first_active_latch
= new_bbs
[n
- 1];
1018 /* Set counts and frequencies. */
1019 if (flags
& DLTHE_FLAG_UPDATE_FREQ
)
1021 scale_bbs_frequencies_int (new_bbs
, n
, scale_act
, REG_BR_PROB_BASE
);
1022 scale_act
= RDIV (scale_act
* scale_step
[j
], REG_BR_PROB_BASE
);
1028 /* Record the exit edge in the original loop body, and update the frequencies. */
1029 if (orig
&& TEST_BIT (wont_exit
, 0))
1032 VEC_safe_push (edge
, heap
, *to_remove
, orig
);
1033 set_zero_probability (orig
);
1035 /* Scale the frequencies of the blocks dominated by the exit. */
1038 EXECUTE_IF_SET_IN_BITMAP (bbs_to_scale
, 0, i
, bi
)
1040 scale_bbs_frequencies_int (bbs
+ i
, 1, scale_after_exit
,
1046 /* Update the original loop. */
1048 set_immediate_dominator (CDI_DOMINATORS
, e
->dest
, e
->src
);
1049 if (flags
& DLTHE_FLAG_UPDATE_FREQ
)
1051 scale_bbs_frequencies_int (bbs
, n
, scale_main
, REG_BR_PROB_BASE
);
1055 /* Update dominators of outer blocks if affected. */
1056 for (i
= 0; i
< n
; i
++)
1058 basic_block dominated
, dom_bb
, *dom_bbs
;
1064 n_dom_bbs
= get_dominated_by (CDI_DOMINATORS
, bb
, &dom_bbs
);
1065 for (j
= 0; j
< n_dom_bbs
; j
++)
1067 dominated
= dom_bbs
[j
];
1068 if (flow_bb_inside_loop_p (loop
, dominated
))
1070 dom_bb
= nearest_common_dominator (
1071 CDI_DOMINATORS
, first_active
[i
], first_active_latch
);
1072 set_immediate_dominator (CDI_DOMINATORS
, dominated
, dom_bb
);
1076 free (first_active
);
1079 BITMAP_FREE (bbs_to_scale
);
1084 /* A callback for make_forwarder block, to redirect all edges except for
1085 MFB_KJ_EDGE to the entry part. E is the edge for that we should decide
1086 whether to redirect it. */
1088 static edge mfb_kj_edge
;
1090 mfb_keep_just (edge e
)
1092 return e
!= mfb_kj_edge
;
1095 /* Creates a pre-header for a LOOP. Returns newly created block. Unless
1096 CP_SIMPLE_PREHEADERS is set in FLAGS, we only force LOOP to have single
1097 entry; otherwise we also force preheader block to have only one successor.
1098 The function also updates dominators. */
1101 create_preheader (struct loop
*loop
, int flags
)
1107 bool latch_edge_was_fallthru
;
1108 edge one_succ_pred
= NULL
, single_entry
= NULL
;
1111 FOR_EACH_EDGE (e
, ei
, loop
->header
->preds
)
1113 if (e
->src
== loop
->latch
)
1115 irred
|= (e
->flags
& EDGE_IRREDUCIBLE_LOOP
) != 0;
1118 if (single_succ_p (e
->src
))
1121 gcc_assert (nentry
);
1124 if (/* We do not allow entry block to be the loop preheader, since we
1125 cannot emit code there. */
1126 single_entry
->src
!= ENTRY_BLOCK_PTR
1127 /* If we want simple preheaders, also force the preheader to have
1128 just a single successor. */
1129 && !((flags
& CP_SIMPLE_PREHEADERS
)
1130 && !single_succ_p (single_entry
->src
)))
1134 mfb_kj_edge
= loop_latch_edge (loop
);
1135 latch_edge_was_fallthru
= (mfb_kj_edge
->flags
& EDGE_FALLTHRU
) != 0;
1136 fallthru
= make_forwarder_block (loop
->header
, mfb_keep_just
, NULL
);
1137 dummy
= fallthru
->src
;
1138 loop
->header
= fallthru
->dest
;
1140 /* Try to be clever in placing the newly created preheader. The idea is to
1141 avoid breaking any "fallthruness" relationship between blocks.
1143 The preheader was created just before the header and all incoming edges
1144 to the header were redirected to the preheader, except the latch edge.
1145 So the only problematic case is when this latch edge was a fallthru
1146 edge: it is not anymore after the preheader creation so we have broken
1147 the fallthruness. We're therefore going to look for a better place. */
1148 if (latch_edge_was_fallthru
)
1153 e
= EDGE_PRED (dummy
, 0);
1155 move_block_after (dummy
, e
->src
);
1160 dummy
->flags
|= BB_IRREDUCIBLE_LOOP
;
1161 single_succ_edge (dummy
)->flags
|= EDGE_IRREDUCIBLE_LOOP
;
1165 fprintf (dump_file
, "Created preheader block for loop %i\n",
1171 /* Create preheaders for each loop; for meaning of FLAGS see create_preheader. */
1174 create_preheaders (int flags
)
1182 FOR_EACH_LOOP (li
, loop
, 0)
1183 create_preheader (loop
, flags
);
1184 current_loops
->state
|= LOOPS_HAVE_PREHEADERS
;
1187 /* Forces all loop latches to have only single successor. */
1190 force_single_succ_latches (void)
1196 FOR_EACH_LOOP (li
, loop
, 0)
1198 if (loop
->latch
!= loop
->header
&& single_succ_p (loop
->latch
))
1201 e
= find_edge (loop
->latch
, loop
->header
);
1205 current_loops
->state
|= LOOPS_HAVE_SIMPLE_LATCHES
;
1208 /* This function is called from loop_version. It splits the entry edge
1209 of the loop we want to version, adds the versioning condition, and
1210 adjust the edges to the two versions of the loop appropriately.
1211 e is an incoming edge. Returns the basic block containing the
1214 --- edge e ---- > [second_head]
1216 Split it and insert new conditional expression and adjust edges.
1218 --- edge e ---> [cond expr] ---> [first_head]
1220 +---------> [second_head]
1222 THEN_PROB is the probability of then branch of the condition. */
1225 lv_adjust_loop_entry_edge (basic_block first_head
, basic_block second_head
,
1226 edge e
, void *cond_expr
, unsigned then_prob
)
1228 basic_block new_head
= NULL
;
1231 gcc_assert (e
->dest
== second_head
);
1233 /* Split edge 'e'. This will create a new basic block, where we can
1234 insert conditional expr. */
1235 new_head
= split_edge (e
);
1237 lv_add_condition_to_bb (first_head
, second_head
, new_head
,
1240 /* Don't set EDGE_TRUE_VALUE in RTL mode, as it's invalid there. */
1241 e
= single_succ_edge (new_head
);
1242 e1
= make_edge (new_head
, first_head
,
1243 current_ir_type () == IR_GIMPLE
? EDGE_TRUE_VALUE
: 0);
1244 e1
->probability
= then_prob
;
1245 e
->probability
= REG_BR_PROB_BASE
- then_prob
;
1246 e1
->count
= RDIV (e
->count
* e1
->probability
, REG_BR_PROB_BASE
);
1247 e
->count
= RDIV (e
->count
* e
->probability
, REG_BR_PROB_BASE
);
1249 set_immediate_dominator (CDI_DOMINATORS
, first_head
, new_head
);
1250 set_immediate_dominator (CDI_DOMINATORS
, second_head
, new_head
);
1252 /* Adjust loop header phi nodes. */
1253 lv_adjust_loop_header_phi (first_head
, second_head
, new_head
, e1
);
1258 /* Main entry point for Loop Versioning transformation.
1260 This transformation given a condition and a loop, creates
1261 -if (condition) { loop_copy1 } else { loop_copy2 },
1262 where loop_copy1 is the loop transformed in one way, and loop_copy2
1263 is the loop transformed in another way (or unchanged). 'condition'
1264 may be a run time test for things that were not resolved by static
1265 analysis (overlapping ranges (anti-aliasing), alignment, etc.).
1267 THEN_PROB is the probability of the then edge of the if. THEN_SCALE
1268 is the ratio by that the frequencies in the original loop should
1269 be scaled. ELSE_SCALE is the ratio by that the frequencies in the
1270 new loop should be scaled.
1272 If PLACE_AFTER is true, we place the new loop after LOOP in the
1273 instruction stream, otherwise it is placed before LOOP. */
1276 loop_version (struct loop
*loop
,
1277 void *cond_expr
, basic_block
*condition_bb
,
1278 unsigned then_prob
, unsigned then_scale
, unsigned else_scale
,
1281 basic_block first_head
, second_head
;
1282 edge entry
, latch_edge
, true_edge
, false_edge
;
1285 basic_block cond_bb
;
1287 /* CHECKME: Loop versioning does not handle nested loop at this point. */
1291 /* Record entry and latch edges for the loop */
1292 entry
= loop_preheader_edge (loop
);
1293 irred_flag
= entry
->flags
& EDGE_IRREDUCIBLE_LOOP
;
1294 entry
->flags
&= ~EDGE_IRREDUCIBLE_LOOP
;
1296 /* Note down head of loop as first_head. */
1297 first_head
= entry
->dest
;
1299 /* Duplicate loop. */
1300 if (!cfg_hook_duplicate_loop_to_header_edge (loop
, entry
, 1,
1301 NULL
, NULL
, NULL
, 0))
1304 /* After duplication entry edge now points to new loop head block.
1305 Note down new head as second_head. */
1306 second_head
= entry
->dest
;
1308 /* Split loop entry edge and insert new block with cond expr. */
1309 cond_bb
= lv_adjust_loop_entry_edge (first_head
, second_head
,
1310 entry
, cond_expr
, then_prob
);
1312 *condition_bb
= cond_bb
;
1316 entry
->flags
|= irred_flag
;
1320 latch_edge
= single_succ_edge (get_bb_copy (loop
->latch
));
1322 extract_cond_bb_edges (cond_bb
, &true_edge
, &false_edge
);
1323 nloop
= loopify (latch_edge
,
1324 single_pred_edge (get_bb_copy (loop
->header
)),
1325 cond_bb
, true_edge
, false_edge
,
1326 false /* Do not redirect all edges. */,
1327 then_scale
, else_scale
);
1329 /* loopify redirected latch_edge. Update its PENDING_STMTS. */
1330 lv_flush_pending_stmts (latch_edge
);
1332 /* loopify redirected condition_bb's succ edge. Update its PENDING_STMTS. */
1333 extract_cond_bb_edges (cond_bb
, &true_edge
, &false_edge
);
1334 lv_flush_pending_stmts (false_edge
);
1335 /* Adjust irreducible flag. */
1338 cond_bb
->flags
|= BB_IRREDUCIBLE_LOOP
;
1339 loop_preheader_edge (loop
)->flags
|= EDGE_IRREDUCIBLE_LOOP
;
1340 loop_preheader_edge (nloop
)->flags
|= EDGE_IRREDUCIBLE_LOOP
;
1341 single_pred_edge (cond_bb
)->flags
|= EDGE_IRREDUCIBLE_LOOP
;
1346 basic_block
*bbs
= get_loop_body_in_dom_order (nloop
), after
;
1349 after
= loop
->latch
;
1351 for (i
= 0; i
< nloop
->num_nodes
; i
++)
1353 move_block_after (bbs
[i
], after
);
1359 /* At this point condition_bb is loop predheader with two successors,
1360 first_head and second_head. Make sure that loop predheader has only
1362 split_edge (loop_preheader_edge (loop
));
1363 split_edge (loop_preheader_edge (nloop
));
1368 /* The structure of loops might have changed. Some loops might get removed
1369 (and their headers and latches were set to NULL), loop exists might get
1370 removed (thus the loop nesting may be wrong), and some blocks and edges
1371 were changed (so the information about bb --> loop mapping does not have
1372 to be correct). But still for the remaining loops the header dominates
1373 the latch, and loops did not get new subloobs (new loops might possibly
1374 get created, but we are not interested in them). Fix up the mess.
1376 If CHANGED_BBS is not NULL, basic blocks whose loop has changed are
1380 fix_loop_structure (bitmap changed_bbs
)
1383 struct loop
*loop
, *ploop
;
1385 bool record_exits
= false;
1386 struct loop
**superloop
= XNEWVEC (struct loop
*, number_of_loops ());
1388 gcc_assert (current_loops
->state
& LOOPS_HAVE_SIMPLE_LATCHES
);
1390 /* Remove the old bb -> loop mapping. Remember the depth of the blocks in
1391 the loop hierarchy, so that we can recognize blocks whose loop nesting
1392 relationship has changed. */
1396 bb
->aux
= (void *) (size_t) bb
->loop_father
->depth
;
1397 bb
->loop_father
= current_loops
->tree_root
;
1400 if (current_loops
->state
& LOOPS_HAVE_RECORDED_EXITS
)
1402 release_recorded_exits ();
1403 record_exits
= true;
1406 /* Remove the dead loops from structures. We start from the innermost
1407 loops, so that when we remove the loops, we know that the loops inside
1408 are preserved, and do not waste time relinking loops that will be
1410 FOR_EACH_LOOP (li
, loop
, LI_FROM_INNERMOST
)
1417 ploop
= loop
->inner
;
1418 flow_loop_tree_node_remove (ploop
);
1419 flow_loop_tree_node_add (loop
->outer
, ploop
);
1422 /* Remove the loop and free its data. */
1426 /* Rescan the bodies of loops, starting from the outermost ones. We assume
1427 that no optimization interchanges the order of the loops, i.e., it cannot
1428 happen that L1 was superloop of L2 before and it is subloop of L2 now
1429 (without explicitly updating loop information). At the same time, we also
1430 determine the new loop structure. */
1431 current_loops
->tree_root
->num_nodes
= n_basic_blocks
;
1432 FOR_EACH_LOOP (li
, loop
, 0)
1434 superloop
[loop
->num
] = loop
->header
->loop_father
;
1435 loop
->num_nodes
= flow_loop_nodes_find (loop
->header
, loop
);
1438 /* Now fix the loop nesting. */
1439 FOR_EACH_LOOP (li
, loop
, 0)
1441 ploop
= superloop
[loop
->num
];
1442 if (ploop
!= loop
->outer
)
1444 flow_loop_tree_node_remove (loop
);
1445 flow_loop_tree_node_add (ploop
, loop
);
1450 /* Mark the blocks whose loop has changed. */
1455 if ((void *) (size_t) bb
->loop_father
->depth
!= bb
->aux
)
1456 bitmap_set_bit (changed_bbs
, bb
->index
);
1462 if (current_loops
->state
& LOOPS_HAVE_PREHEADERS
)
1463 create_preheaders (CP_SIMPLE_PREHEADERS
);
1465 if (current_loops
->state
& LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS
)
1466 mark_irreducible_loops ();
1469 record_loop_exits ();
1471 #ifdef ENABLE_CHECKING
1472 verify_loop_structure ();