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 void unloop (struct loop
*, bool *);
46 #define RDIV(X,Y) (((X) + (Y) / 2) / (Y))
48 /* Checks whether basic block BB is dominated by DATA. */
50 rpe_enum_p (basic_block bb
, void *data
)
52 return dominated_by_p (CDI_DOMINATORS
, bb
, (basic_block
) data
);
55 /* Remove basic blocks BBS. NBBS is the number of the basic blocks. */
58 remove_bbs (basic_block
*bbs
, int nbbs
)
62 for (i
= 0; i
< nbbs
; i
++)
63 delete_basic_block (bbs
[i
]);
66 /* Find path -- i.e. the basic blocks dominated by edge E and put them
67 into array BBS, that will be allocated large enough to contain them.
68 E->dest must have exactly one predecessor for this to work (it is
69 easy to achieve and we do not put it here because we do not want to
70 alter anything by this function). The number of basic blocks in the
73 find_path (edge e
, basic_block
**bbs
)
75 gcc_assert (EDGE_COUNT (e
->dest
->preds
) <= 1);
77 /* Find bbs in the path. */
78 *bbs
= XCNEWVEC (basic_block
, n_basic_blocks
);
79 return dfs_enumerate_from (e
->dest
, 0, rpe_enum_p
, *bbs
,
80 n_basic_blocks
, e
->dest
);
83 /* Fix placement of basic block BB inside loop hierarchy --
84 Let L be a loop to that BB belongs. Then every successor of BB must either
85 1) belong to some superloop of loop L, or
86 2) be a header of loop K such that K->outer is superloop of L
87 Returns true if we had to move BB into other loop to enforce this condition,
88 false if the placement of BB was already correct (provided that placements
89 of its successors are correct). */
91 fix_bb_placement (basic_block bb
)
95 struct loop
*loop
= current_loops
->tree_root
, *act
;
97 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
99 if (e
->dest
== EXIT_BLOCK_PTR
)
102 act
= e
->dest
->loop_father
;
103 if (act
->header
== e
->dest
)
104 act
= loop_outer (act
);
106 if (flow_loop_nested_p (loop
, act
))
110 if (loop
== bb
->loop_father
)
113 remove_bb_from_loops (bb
);
114 add_bb_to_loop (bb
, loop
);
119 /* Fix placement of LOOP inside loop tree, i.e. find the innermost superloop
120 of LOOP to that leads at least one exit edge of LOOP, and set it
121 as the immediate superloop of LOOP. Return true if the immediate superloop
125 fix_loop_placement (struct loop
*loop
)
129 VEC (edge
, heap
) *exits
= get_loop_exit_edges (loop
);
130 struct loop
*father
= current_loops
->tree_root
, *act
;
133 for (i
= 0; VEC_iterate (edge
, exits
, i
, e
); i
++)
135 act
= find_common_loop (loop
, e
->dest
->loop_father
);
136 if (flow_loop_nested_p (father
, act
))
140 if (father
!= loop_outer (loop
))
142 for (act
= loop_outer (loop
); act
!= father
; act
= loop_outer (act
))
143 act
->num_nodes
-= loop
->num_nodes
;
144 flow_loop_tree_node_remove (loop
);
145 flow_loop_tree_node_add (father
, loop
);
147 /* The exit edges of LOOP no longer exits its original immediate
148 superloops; remove them from the appropriate exit lists. */
149 for (i
= 0; VEC_iterate (edge
, exits
, i
, e
); i
++)
150 rescan_loop_exit (e
, false, false);
155 VEC_free (edge
, heap
, exits
);
159 /* Fix placements of basic blocks inside loop hierarchy stored in loops; i.e.
160 enforce condition condition stated in description of fix_bb_placement. We
161 start from basic block FROM that had some of its successors removed, so that
162 his placement no longer has to be correct, and iteratively fix placement of
163 its predecessors that may change if placement of FROM changed. Also fix
164 placement of subloops of FROM->loop_father, that might also be altered due
165 to this change; the condition for them is similar, except that instead of
166 successors we consider edges coming out of the loops.
168 If the changes may invalidate the information about irreducible regions,
169 IRRED_INVALIDATED is set to true. */
172 fix_bb_placements (basic_block from
,
173 bool *irred_invalidated
)
176 basic_block
*queue
, *qtop
, *qbeg
, *qend
;
177 struct loop
*base_loop
;
180 /* We pass through blocks back-reachable from FROM, testing whether some
181 of their successors moved to outer loop. It may be necessary to
182 iterate several times, but it is finite, as we stop unless we move
183 the basic block up the loop structure. The whole story is a bit
184 more complicated due to presence of subloops, those are moved using
185 fix_loop_placement. */
187 base_loop
= from
->loop_father
;
188 if (base_loop
== current_loops
->tree_root
)
191 in_queue
= sbitmap_alloc (last_basic_block
);
192 sbitmap_zero (in_queue
);
193 SET_BIT (in_queue
, from
->index
);
194 /* Prevent us from going out of the base_loop. */
195 SET_BIT (in_queue
, base_loop
->header
->index
);
197 queue
= XNEWVEC (basic_block
, base_loop
->num_nodes
+ 1);
198 qtop
= queue
+ base_loop
->num_nodes
+ 1;
210 RESET_BIT (in_queue
, from
->index
);
212 if (from
->loop_father
->header
== from
)
214 /* Subloop header, maybe move the loop upward. */
215 if (!fix_loop_placement (from
->loop_father
))
220 /* Ordinary basic block. */
221 if (!fix_bb_placement (from
))
225 FOR_EACH_EDGE (e
, ei
, from
->succs
)
227 if (e
->flags
& EDGE_IRREDUCIBLE_LOOP
)
228 *irred_invalidated
= true;
231 /* Something has changed, insert predecessors into queue. */
232 FOR_EACH_EDGE (e
, ei
, from
->preds
)
234 basic_block pred
= e
->src
;
237 if (e
->flags
& EDGE_IRREDUCIBLE_LOOP
)
238 *irred_invalidated
= true;
240 if (TEST_BIT (in_queue
, pred
->index
))
243 /* If it is subloop, then it either was not moved, or
244 the path up the loop tree from base_loop do not contain
246 nca
= find_common_loop (pred
->loop_father
, base_loop
);
247 if (pred
->loop_father
!= base_loop
249 || nca
!= pred
->loop_father
))
250 pred
= pred
->loop_father
->header
;
251 else if (!flow_loop_nested_p (from
->loop_father
, pred
->loop_father
))
253 /* No point in processing it. */
257 if (TEST_BIT (in_queue
, pred
->index
))
260 /* Schedule the basic block. */
265 SET_BIT (in_queue
, pred
->index
);
272 /* Removes path beginning at edge E, i.e. remove basic blocks dominated by E
273 and update loop structures and dominators. Return true if we were able
274 to remove the path, false otherwise (and nothing is affected then). */
279 basic_block
*rem_bbs
, *bord_bbs
, from
, bb
;
280 VEC (basic_block
, heap
) *dom_bbs
;
281 int i
, nrem
, n_bord_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 (loop_outer (e
->src
->loop_father
)
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. */
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. */
360 for (i
= 0; i
< n_bord_bbs
; i
++)
364 bb
= get_immediate_dominator (CDI_DOMINATORS
, bord_bbs
[i
]);
365 if (TEST_BIT (seen
, bb
->index
))
367 SET_BIT (seen
, bb
->index
);
369 for (ldom
= first_dom_son (CDI_DOMINATORS
, bb
);
371 ldom
= next_dom_son (CDI_DOMINATORS
, ldom
))
372 if (!dominated_by_p (CDI_DOMINATORS
, from
, ldom
))
373 VEC_safe_push (basic_block
, heap
, dom_bbs
, ldom
);
378 /* Recount dominators. */
379 iterate_fix_dominators (CDI_DOMINATORS
, dom_bbs
, true);
380 VEC_free (basic_block
, heap
, dom_bbs
);
383 /* Fix placements of basic blocks inside loops and the placement of
384 loops in the loop tree. */
385 fix_bb_placements (from
, &irred_invalidated
);
386 fix_loop_placements (from
->loop_father
, &irred_invalidated
);
388 if (irred_invalidated
389 && (current_loops
->state
& LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS
) != 0)
390 mark_irreducible_loops ();
395 /* Creates place for a new LOOP in loops structure. */
398 place_new_loop (struct loop
*loop
)
400 loop
->num
= number_of_loops ();
401 VEC_safe_push (loop_p
, gc
, current_loops
->larray
, loop
);
404 /* Given LOOP structure with filled header and latch, find the body of the
405 corresponding loop and add it to loops tree. Insert the LOOP as a son of
409 add_loop (struct loop
*loop
, struct loop
*outer
)
413 struct loop
*subloop
;
415 /* Add it to loop structure. */
416 place_new_loop (loop
);
417 flow_loop_tree_node_add (outer
, loop
);
419 /* Find its nodes. */
420 bbs
= XNEWVEC (basic_block
, n_basic_blocks
);
421 n
= get_loop_body_with_size (loop
, bbs
, n_basic_blocks
);
423 for (i
= 0; i
< n
; i
++)
425 if (bbs
[i
]->loop_father
== outer
)
427 remove_bb_from_loops (bbs
[i
]);
428 add_bb_to_loop (bbs
[i
], loop
);
434 /* If we find a direct subloop of OUTER, move it to LOOP. */
435 subloop
= bbs
[i
]->loop_father
;
436 if (loop_outer (subloop
) == outer
437 && subloop
->header
== bbs
[i
])
439 flow_loop_tree_node_remove (subloop
);
440 flow_loop_tree_node_add (loop
, subloop
);
447 /* Multiply all frequencies in LOOP by NUM/DEN. */
449 scale_loop_frequencies (struct loop
*loop
, int num
, int den
)
453 bbs
= get_loop_body (loop
);
454 scale_bbs_frequencies_int (bbs
, loop
->num_nodes
, num
, den
);
458 /* Make area between HEADER_EDGE and LATCH_EDGE a loop by connecting
459 latch to header and update loop tree and dominators
460 accordingly. Everything between them plus LATCH_EDGE destination must
461 be dominated by HEADER_EDGE destination, and back-reachable from
462 LATCH_EDGE source. HEADER_EDGE is redirected to basic block SWITCH_BB,
463 FALSE_EDGE of SWITCH_BB to original destination of HEADER_EDGE and
464 TRUE_EDGE of SWITCH_BB to original destination of LATCH_EDGE.
465 Returns the newly created loop. Frequencies and counts in the new loop
466 are scaled by FALSE_SCALE and in the old one by TRUE_SCALE. */
469 loopify (edge latch_edge
, edge header_edge
,
470 basic_block switch_bb
, edge true_edge
, edge false_edge
,
471 bool redirect_all_edges
, unsigned true_scale
, unsigned false_scale
)
473 basic_block succ_bb
= latch_edge
->dest
;
474 basic_block pred_bb
= header_edge
->src
;
476 VEC (basic_block
, heap
) *dom_bbs
;
479 struct loop
*loop
= alloc_loop ();
480 struct loop
*outer
= loop_outer (succ_bb
->loop_father
);
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. */
533 seen
= sbitmap_alloc (last_basic_block
);
535 body
= get_loop_body (loop
);
537 for (i
= 0; i
< loop
->num_nodes
; i
++)
538 SET_BIT (seen
, body
[i
]->index
);
540 for (i
= 0; i
< loop
->num_nodes
; i
++)
544 for (ldom
= first_dom_son (CDI_DOMINATORS
, body
[i
]);
546 ldom
= next_dom_son (CDI_DOMINATORS
, ldom
))
547 if (!TEST_BIT (seen
, ldom
->index
))
549 SET_BIT (seen
, ldom
->index
);
550 VEC_safe_push (basic_block
, heap
, dom_bbs
, ldom
);
554 iterate_fix_dominators (CDI_DOMINATORS
, dom_bbs
, false);
558 VEC_free (basic_block
, heap
, dom_bbs
);
563 /* Remove the latch edge of a LOOP and update loops to indicate that
564 the LOOP was removed. After this function, original loop latch will
565 have no successor, which caller is expected to fix somehow.
567 If this may cause the information about irreducible regions to become
568 invalid, IRRED_INVALIDATED is set to true. */
571 unloop (struct loop
*loop
, bool *irred_invalidated
)
576 basic_block latch
= loop
->latch
;
579 if (loop_preheader_edge (loop
)->flags
& EDGE_IRREDUCIBLE_LOOP
)
580 *irred_invalidated
= true;
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
);
590 for (i
= 0; i
< n
; i
++)
591 if (body
[i
]->loop_father
== loop
)
593 remove_bb_from_loops (body
[i
]);
594 add_bb_to_loop (body
[i
], loop_outer (loop
));
601 flow_loop_tree_node_remove (ploop
);
602 flow_loop_tree_node_add (loop_outer (loop
), ploop
);
605 /* Remove the loop and free its data. */
608 remove_edge (single_succ_edge (latch
));
610 /* We do not pass IRRED_INVALIDATED to fix_bb_placements here, as even if
611 there is an irreducible region inside the cancelled loop, the flags will
613 fix_bb_placements (latch
, &dummy
);
616 /* Fix placement of superloops of LOOP inside loop tree, i.e. ensure that
617 condition stated in description of fix_loop_placement holds for them.
618 It is used in case when we removed some edges coming out of LOOP, which
619 may cause the right placement of LOOP inside loop tree to change.
621 IRRED_INVALIDATED is set to true if a change in the loop structures might
622 invalidate the information about irreducible regions. */
625 fix_loop_placements (struct loop
*loop
, bool *irred_invalidated
)
629 while (loop_outer (loop
))
631 outer
= loop_outer (loop
);
632 if (!fix_loop_placement (loop
))
635 /* Changing the placement of a loop in the loop tree may alter the
636 validity of condition 2) of the description of fix_bb_placement
637 for its preheader, because the successor is the header and belongs
638 to the loop. So call fix_bb_placements to fix up the placement
639 of the preheader and (possibly) of its predecessors. */
640 fix_bb_placements (loop_preheader_edge (loop
)->src
,
646 /* Copies copy of LOOP as subloop of TARGET loop, placing newly
647 created loop into loops structure. */
649 duplicate_loop (struct loop
*loop
, struct loop
*target
)
652 cloop
= alloc_loop ();
653 place_new_loop (cloop
);
655 /* Mark the new loop as copy of LOOP. */
656 set_loop_copy (loop
, cloop
);
658 /* Add it to target. */
659 flow_loop_tree_node_add (target
, cloop
);
664 /* Copies structure of subloops of LOOP into TARGET loop, placing
665 newly created loops into loop tree. */
667 duplicate_subloops (struct loop
*loop
, struct loop
*target
)
669 struct loop
*aloop
, *cloop
;
671 for (aloop
= loop
->inner
; aloop
; aloop
= aloop
->next
)
673 cloop
= duplicate_loop (aloop
, target
);
674 duplicate_subloops (aloop
, cloop
);
678 /* Copies structure of subloops of N loops, stored in array COPIED_LOOPS,
679 into TARGET loop, placing newly created loops into loop tree. */
681 copy_loops_to (struct loop
**copied_loops
, int n
, struct loop
*target
)
686 for (i
= 0; i
< n
; i
++)
688 aloop
= duplicate_loop (copied_loops
[i
], target
);
689 duplicate_subloops (copied_loops
[i
], aloop
);
693 /* Redirects edge E to basic block DEST. */
695 loop_redirect_edge (edge e
, basic_block dest
)
700 redirect_edge_and_branch_force (e
, dest
);
703 /* Check whether LOOP's body can be duplicated. */
705 can_duplicate_loop_p (struct loop
*loop
)
708 basic_block
*bbs
= get_loop_body (loop
);
710 ret
= can_copy_bbs_p (bbs
, loop
->num_nodes
);
716 /* Sets probability and count of edge E to zero. The probability and count
717 is redistributed evenly to the remaining edges coming from E->src. */
720 set_zero_probability (edge e
)
722 basic_block bb
= e
->src
;
724 edge ae
, last
= NULL
;
725 unsigned n
= EDGE_COUNT (bb
->succs
);
726 gcov_type cnt
= e
->count
, cnt1
;
727 unsigned prob
= e
->probability
, prob1
;
730 cnt1
= cnt
/ (n
- 1);
731 prob1
= prob
/ (n
- 1);
733 FOR_EACH_EDGE (ae
, ei
, bb
->succs
)
738 ae
->probability
+= prob1
;
743 /* Move the rest to one of the edges. */
744 last
->probability
+= prob
% (n
- 1);
745 last
->count
+= cnt
% (n
- 1);
751 /* Duplicates body of LOOP to given edge E NDUPL times. Takes care of updating
752 loop structure and dominators. E's destination must be LOOP header for
753 this to work, i.e. it must be entry or latch edge of this loop; these are
754 unique, as the loops must have preheaders for this function to work
755 correctly (in case E is latch, the function unrolls the loop, if E is entry
756 edge, it peels the loop). Store edges created by copying ORIG edge from
757 copies corresponding to set bits in WONT_EXIT bitmap (bit 0 corresponds to
758 original LOOP body, the other copies are numbered in order given by control
759 flow through them) into TO_REMOVE array. Returns false if duplication is
763 duplicate_loop_to_header_edge (struct loop
*loop
, edge e
,
764 unsigned int ndupl
, sbitmap wont_exit
,
765 edge orig
, VEC (edge
, heap
) **to_remove
,
768 struct loop
*target
, *aloop
;
769 struct loop
**orig_loops
;
770 unsigned n_orig_loops
;
771 basic_block header
= loop
->header
, latch
= loop
->latch
;
772 basic_block
*new_bbs
, *bbs
, *first_active
;
773 basic_block new_bb
, bb
, first_active_latch
= NULL
;
775 edge spec_edges
[2], new_spec_edges
[2];
779 int is_latch
= (latch
== e
->src
);
780 int scale_act
= 0, *scale_step
= NULL
, scale_main
= 0;
781 int scale_after_exit
= 0;
782 int p
, freq_in
, freq_le
, freq_out_orig
;
783 int prob_pass_thru
, prob_pass_wont_exit
, prob_pass_main
;
784 int add_irreducible_flag
;
785 basic_block place_after
;
786 bitmap bbs_to_scale
= NULL
;
789 gcc_assert (e
->dest
== loop
->header
);
790 gcc_assert (ndupl
> 0);
794 /* Orig must be edge out of the loop. */
795 gcc_assert (flow_bb_inside_loop_p (loop
, orig
->src
));
796 gcc_assert (!flow_bb_inside_loop_p (loop
, orig
->dest
));
800 bbs
= get_loop_body_in_dom_order (loop
);
801 gcc_assert (bbs
[0] == loop
->header
);
802 gcc_assert (bbs
[n
- 1] == loop
->latch
);
804 /* Check whether duplication is possible. */
805 if (!can_copy_bbs_p (bbs
, loop
->num_nodes
))
810 new_bbs
= XNEWVEC (basic_block
, loop
->num_nodes
);
812 /* In case we are doing loop peeling and the loop is in the middle of
813 irreducible region, the peeled copies will be inside it too. */
814 add_irreducible_flag
= e
->flags
& EDGE_IRREDUCIBLE_LOOP
;
815 gcc_assert (!is_latch
|| !add_irreducible_flag
);
817 /* Find edge from latch. */
818 latch_edge
= loop_latch_edge (loop
);
820 if (flags
& DLTHE_FLAG_UPDATE_FREQ
)
822 /* Calculate coefficients by that we have to scale frequencies
823 of duplicated loop bodies. */
824 freq_in
= header
->frequency
;
825 freq_le
= EDGE_FREQUENCY (latch_edge
);
828 if (freq_in
< freq_le
)
830 freq_out_orig
= orig
? EDGE_FREQUENCY (orig
) : freq_in
- freq_le
;
831 if (freq_out_orig
> freq_in
- freq_le
)
832 freq_out_orig
= freq_in
- freq_le
;
833 prob_pass_thru
= RDIV (REG_BR_PROB_BASE
* freq_le
, freq_in
);
834 prob_pass_wont_exit
=
835 RDIV (REG_BR_PROB_BASE
* (freq_le
+ freq_out_orig
), freq_in
);
838 && REG_BR_PROB_BASE
- orig
->probability
!= 0)
840 /* The blocks that are dominated by a removed exit edge ORIG have
841 frequencies scaled by this. */
842 scale_after_exit
= RDIV (REG_BR_PROB_BASE
* REG_BR_PROB_BASE
,
843 REG_BR_PROB_BASE
- orig
->probability
);
844 bbs_to_scale
= BITMAP_ALLOC (NULL
);
845 for (i
= 0; i
< n
; i
++)
847 if (bbs
[i
] != orig
->src
848 && dominated_by_p (CDI_DOMINATORS
, bbs
[i
], orig
->src
))
849 bitmap_set_bit (bbs_to_scale
, i
);
853 scale_step
= XNEWVEC (int, ndupl
);
855 for (i
= 1; i
<= ndupl
; i
++)
856 scale_step
[i
- 1] = TEST_BIT (wont_exit
, i
)
857 ? prob_pass_wont_exit
860 /* Complete peeling is special as the probability of exit in last
862 if (flags
& DLTHE_FLAG_COMPLETTE_PEEL
)
864 int wanted_freq
= EDGE_FREQUENCY (e
);
866 if (wanted_freq
> freq_in
)
867 wanted_freq
= freq_in
;
869 gcc_assert (!is_latch
);
870 /* First copy has frequency of incoming edge. Each subsequent
871 frequency should be reduced by prob_pass_wont_exit. Caller
872 should've managed the flags so all except for original loop
873 has won't exist set. */
874 scale_act
= RDIV (wanted_freq
* REG_BR_PROB_BASE
, freq_in
);
875 /* Now simulate the duplication adjustments and compute header
876 frequency of the last copy. */
877 for (i
= 0; i
< ndupl
; i
++)
878 wanted_freq
= RDIV (wanted_freq
* scale_step
[i
], REG_BR_PROB_BASE
);
879 scale_main
= RDIV (wanted_freq
* REG_BR_PROB_BASE
, freq_in
);
883 prob_pass_main
= TEST_BIT (wont_exit
, 0)
884 ? prob_pass_wont_exit
887 scale_main
= REG_BR_PROB_BASE
;
888 for (i
= 0; i
< ndupl
; i
++)
891 p
= RDIV (p
* scale_step
[i
], REG_BR_PROB_BASE
);
893 scale_main
= RDIV (REG_BR_PROB_BASE
* REG_BR_PROB_BASE
, scale_main
);
894 scale_act
= RDIV (scale_main
* prob_pass_main
, REG_BR_PROB_BASE
);
898 scale_main
= REG_BR_PROB_BASE
;
899 for (i
= 0; i
< ndupl
; i
++)
900 scale_main
= RDIV (scale_main
* scale_step
[i
], REG_BR_PROB_BASE
);
901 scale_act
= REG_BR_PROB_BASE
- prob_pass_thru
;
903 for (i
= 0; i
< ndupl
; i
++)
904 gcc_assert (scale_step
[i
] >= 0 && scale_step
[i
] <= REG_BR_PROB_BASE
);
905 gcc_assert (scale_main
>= 0 && scale_main
<= REG_BR_PROB_BASE
906 && scale_act
>= 0 && scale_act
<= REG_BR_PROB_BASE
);
909 /* Loop the new bbs will belong to. */
910 target
= e
->src
->loop_father
;
912 /* Original loops. */
914 for (aloop
= loop
->inner
; aloop
; aloop
= aloop
->next
)
916 orig_loops
= XCNEWVEC (struct loop
*, n_orig_loops
);
917 for (aloop
= loop
->inner
, i
= 0; aloop
; aloop
= aloop
->next
, i
++)
918 orig_loops
[i
] = aloop
;
920 set_loop_copy (loop
, target
);
922 first_active
= XNEWVEC (basic_block
, n
);
925 memcpy (first_active
, bbs
, n
* sizeof (basic_block
));
926 first_active_latch
= latch
;
929 spec_edges
[SE_ORIG
] = orig
;
930 spec_edges
[SE_LATCH
] = latch_edge
;
932 place_after
= e
->src
;
933 for (j
= 0; j
< ndupl
; j
++)
936 copy_loops_to (orig_loops
, n_orig_loops
, target
);
939 copy_bbs (bbs
, n
, new_bbs
, spec_edges
, 2, new_spec_edges
, loop
,
941 place_after
= new_spec_edges
[SE_LATCH
]->src
;
943 if (flags
& DLTHE_RECORD_COPY_NUMBER
)
944 for (i
= 0; i
< n
; i
++)
946 gcc_assert (!new_bbs
[i
]->aux
);
947 new_bbs
[i
]->aux
= (void *)(size_t)(j
+ 1);
950 /* Note whether the blocks and edges belong to an irreducible loop. */
951 if (add_irreducible_flag
)
953 for (i
= 0; i
< n
; i
++)
954 new_bbs
[i
]->flags
|= BB_DUPLICATED
;
955 for (i
= 0; i
< n
; i
++)
959 if (new_bb
->loop_father
== target
)
960 new_bb
->flags
|= BB_IRREDUCIBLE_LOOP
;
962 FOR_EACH_EDGE (ae
, ei
, new_bb
->succs
)
963 if ((ae
->dest
->flags
& BB_DUPLICATED
)
964 && (ae
->src
->loop_father
== target
965 || ae
->dest
->loop_father
== target
))
966 ae
->flags
|= EDGE_IRREDUCIBLE_LOOP
;
968 for (i
= 0; i
< n
; i
++)
969 new_bbs
[i
]->flags
&= ~BB_DUPLICATED
;
972 /* Redirect the special edges. */
975 redirect_edge_and_branch_force (latch_edge
, new_bbs
[0]);
976 redirect_edge_and_branch_force (new_spec_edges
[SE_LATCH
],
978 set_immediate_dominator (CDI_DOMINATORS
, new_bbs
[0], latch
);
979 latch
= loop
->latch
= new_bbs
[n
- 1];
980 e
= latch_edge
= new_spec_edges
[SE_LATCH
];
984 redirect_edge_and_branch_force (new_spec_edges
[SE_LATCH
],
986 redirect_edge_and_branch_force (e
, new_bbs
[0]);
987 set_immediate_dominator (CDI_DOMINATORS
, new_bbs
[0], e
->src
);
988 e
= new_spec_edges
[SE_LATCH
];
991 /* Record exit edge in this copy. */
992 if (orig
&& TEST_BIT (wont_exit
, j
+ 1))
995 VEC_safe_push (edge
, heap
, *to_remove
, new_spec_edges
[SE_ORIG
]);
996 set_zero_probability (new_spec_edges
[SE_ORIG
]);
998 /* Scale the frequencies of the blocks dominated by the exit. */
1001 EXECUTE_IF_SET_IN_BITMAP (bbs_to_scale
, 0, i
, bi
)
1003 scale_bbs_frequencies_int (new_bbs
+ i
, 1, scale_after_exit
,
1009 /* Record the first copy in the control flow order if it is not
1010 the original loop (i.e. in case of peeling). */
1011 if (!first_active_latch
)
1013 memcpy (first_active
, new_bbs
, n
* sizeof (basic_block
));
1014 first_active_latch
= new_bbs
[n
- 1];
1017 /* Set counts and frequencies. */
1018 if (flags
& DLTHE_FLAG_UPDATE_FREQ
)
1020 scale_bbs_frequencies_int (new_bbs
, n
, scale_act
, REG_BR_PROB_BASE
);
1021 scale_act
= RDIV (scale_act
* scale_step
[j
], REG_BR_PROB_BASE
);
1027 /* Record the exit edge in the original loop body, and update the frequencies. */
1028 if (orig
&& TEST_BIT (wont_exit
, 0))
1031 VEC_safe_push (edge
, heap
, *to_remove
, orig
);
1032 set_zero_probability (orig
);
1034 /* Scale the frequencies of the blocks dominated by the exit. */
1037 EXECUTE_IF_SET_IN_BITMAP (bbs_to_scale
, 0, i
, bi
)
1039 scale_bbs_frequencies_int (bbs
+ i
, 1, scale_after_exit
,
1045 /* Update the original loop. */
1047 set_immediate_dominator (CDI_DOMINATORS
, e
->dest
, e
->src
);
1048 if (flags
& DLTHE_FLAG_UPDATE_FREQ
)
1050 scale_bbs_frequencies_int (bbs
, n
, scale_main
, REG_BR_PROB_BASE
);
1054 /* Update dominators of outer blocks if affected. */
1055 for (i
= 0; i
< n
; i
++)
1057 basic_block dominated
, dom_bb
;
1058 VEC (basic_block
, heap
) *dom_bbs
;
1064 dom_bbs
= get_dominated_by (CDI_DOMINATORS
, bb
);
1065 for (j
= 0; VEC_iterate (basic_block
, dom_bbs
, j
, dominated
); j
++)
1067 if (flow_bb_inside_loop_p (loop
, dominated
))
1069 dom_bb
= nearest_common_dominator (
1070 CDI_DOMINATORS
, first_active
[i
], first_active_latch
);
1071 set_immediate_dominator (CDI_DOMINATORS
, dominated
, dom_bb
);
1073 VEC_free (basic_block
, heap
, dom_bbs
);
1075 free (first_active
);
1078 BITMAP_FREE (bbs_to_scale
);
1083 /* A callback for make_forwarder block, to redirect all edges except for
1084 MFB_KJ_EDGE to the entry part. E is the edge for that we should decide
1085 whether to redirect it. */
1089 mfb_keep_just (edge e
)
1091 return e
!= mfb_kj_edge
;
1094 /* Creates a pre-header for a LOOP. Returns newly created block. Unless
1095 CP_SIMPLE_PREHEADERS is set in FLAGS, we only force LOOP to have single
1096 entry; otherwise we also force preheader block to have only one successor.
1097 The function also updates dominators. */
1100 create_preheader (struct loop
*loop
, int flags
)
1106 bool latch_edge_was_fallthru
;
1107 edge one_succ_pred
= NULL
, single_entry
= NULL
;
1110 FOR_EACH_EDGE (e
, ei
, loop
->header
->preds
)
1112 if (e
->src
== loop
->latch
)
1114 irred
|= (e
->flags
& EDGE_IRREDUCIBLE_LOOP
) != 0;
1117 if (single_succ_p (e
->src
))
1120 gcc_assert (nentry
);
1123 if (/* We do not allow entry block to be the loop preheader, since we
1124 cannot emit code there. */
1125 single_entry
->src
!= ENTRY_BLOCK_PTR
1126 /* If we want simple preheaders, also force the preheader to have
1127 just a single successor. */
1128 && !((flags
& CP_SIMPLE_PREHEADERS
)
1129 && !single_succ_p (single_entry
->src
)))
1133 mfb_kj_edge
= loop_latch_edge (loop
);
1134 latch_edge_was_fallthru
= (mfb_kj_edge
->flags
& EDGE_FALLTHRU
) != 0;
1135 fallthru
= make_forwarder_block (loop
->header
, mfb_keep_just
, NULL
);
1136 dummy
= fallthru
->src
;
1137 loop
->header
= fallthru
->dest
;
1139 /* Try to be clever in placing the newly created preheader. The idea is to
1140 avoid breaking any "fallthruness" relationship between blocks.
1142 The preheader was created just before the header and all incoming edges
1143 to the header were redirected to the preheader, except the latch edge.
1144 So the only problematic case is when this latch edge was a fallthru
1145 edge: it is not anymore after the preheader creation so we have broken
1146 the fallthruness. We're therefore going to look for a better place. */
1147 if (latch_edge_was_fallthru
)
1152 e
= EDGE_PRED (dummy
, 0);
1154 move_block_after (dummy
, e
->src
);
1159 dummy
->flags
|= BB_IRREDUCIBLE_LOOP
;
1160 single_succ_edge (dummy
)->flags
|= EDGE_IRREDUCIBLE_LOOP
;
1164 fprintf (dump_file
, "Created preheader block for loop %i\n",
1170 /* Create preheaders for each loop; for meaning of FLAGS see create_preheader. */
1173 create_preheaders (int flags
)
1181 FOR_EACH_LOOP (li
, loop
, 0)
1182 create_preheader (loop
, flags
);
1183 current_loops
->state
|= LOOPS_HAVE_PREHEADERS
;
1186 /* Forces all loop latches to have only single successor. */
1189 force_single_succ_latches (void)
1195 FOR_EACH_LOOP (li
, loop
, 0)
1197 if (loop
->latch
!= loop
->header
&& single_succ_p (loop
->latch
))
1200 e
= find_edge (loop
->latch
, loop
->header
);
1204 current_loops
->state
|= LOOPS_HAVE_SIMPLE_LATCHES
;
1207 /* This function is called from loop_version. It splits the entry edge
1208 of the loop we want to version, adds the versioning condition, and
1209 adjust the edges to the two versions of the loop appropriately.
1210 e is an incoming edge. Returns the basic block containing the
1213 --- edge e ---- > [second_head]
1215 Split it and insert new conditional expression and adjust edges.
1217 --- edge e ---> [cond expr] ---> [first_head]
1219 +---------> [second_head]
1221 THEN_PROB is the probability of then branch of the condition. */
1224 lv_adjust_loop_entry_edge (basic_block first_head
, basic_block second_head
,
1225 edge e
, void *cond_expr
, unsigned then_prob
)
1227 basic_block new_head
= NULL
;
1230 gcc_assert (e
->dest
== second_head
);
1232 /* Split edge 'e'. This will create a new basic block, where we can
1233 insert conditional expr. */
1234 new_head
= split_edge (e
);
1236 lv_add_condition_to_bb (first_head
, second_head
, new_head
,
1239 /* Don't set EDGE_TRUE_VALUE in RTL mode, as it's invalid there. */
1240 e
= single_succ_edge (new_head
);
1241 e1
= make_edge (new_head
, first_head
,
1242 current_ir_type () == IR_GIMPLE
? EDGE_TRUE_VALUE
: 0);
1243 e1
->probability
= then_prob
;
1244 e
->probability
= REG_BR_PROB_BASE
- then_prob
;
1245 e1
->count
= RDIV (e
->count
* e1
->probability
, REG_BR_PROB_BASE
);
1246 e
->count
= RDIV (e
->count
* e
->probability
, REG_BR_PROB_BASE
);
1248 set_immediate_dominator (CDI_DOMINATORS
, first_head
, new_head
);
1249 set_immediate_dominator (CDI_DOMINATORS
, second_head
, new_head
);
1251 /* Adjust loop header phi nodes. */
1252 lv_adjust_loop_header_phi (first_head
, second_head
, new_head
, e1
);
1257 /* Main entry point for Loop Versioning transformation.
1259 This transformation given a condition and a loop, creates
1260 -if (condition) { loop_copy1 } else { loop_copy2 },
1261 where loop_copy1 is the loop transformed in one way, and loop_copy2
1262 is the loop transformed in another way (or unchanged). 'condition'
1263 may be a run time test for things that were not resolved by static
1264 analysis (overlapping ranges (anti-aliasing), alignment, etc.).
1266 THEN_PROB is the probability of the then edge of the if. THEN_SCALE
1267 is the ratio by that the frequencies in the original loop should
1268 be scaled. ELSE_SCALE is the ratio by that the frequencies in the
1269 new loop should be scaled.
1271 If PLACE_AFTER is true, we place the new loop after LOOP in the
1272 instruction stream, otherwise it is placed before LOOP. */
1275 loop_version (struct loop
*loop
,
1276 void *cond_expr
, basic_block
*condition_bb
,
1277 unsigned then_prob
, unsigned then_scale
, unsigned else_scale
,
1280 basic_block first_head
, second_head
;
1281 edge entry
, latch_edge
, true_edge
, false_edge
;
1284 basic_block cond_bb
;
1286 /* CHECKME: Loop versioning does not handle nested loop at this point. */
1290 /* Record entry and latch edges for the loop */
1291 entry
= loop_preheader_edge (loop
);
1292 irred_flag
= entry
->flags
& EDGE_IRREDUCIBLE_LOOP
;
1293 entry
->flags
&= ~EDGE_IRREDUCIBLE_LOOP
;
1295 /* Note down head of loop as first_head. */
1296 first_head
= entry
->dest
;
1298 /* Duplicate loop. */
1299 if (!cfg_hook_duplicate_loop_to_header_edge (loop
, entry
, 1,
1300 NULL
, NULL
, NULL
, 0))
1303 /* After duplication entry edge now points to new loop head block.
1304 Note down new head as second_head. */
1305 second_head
= entry
->dest
;
1307 /* Split loop entry edge and insert new block with cond expr. */
1308 cond_bb
= lv_adjust_loop_entry_edge (first_head
, second_head
,
1309 entry
, cond_expr
, then_prob
);
1311 *condition_bb
= cond_bb
;
1315 entry
->flags
|= irred_flag
;
1319 latch_edge
= single_succ_edge (get_bb_copy (loop
->latch
));
1321 extract_cond_bb_edges (cond_bb
, &true_edge
, &false_edge
);
1322 nloop
= loopify (latch_edge
,
1323 single_pred_edge (get_bb_copy (loop
->header
)),
1324 cond_bb
, true_edge
, false_edge
,
1325 false /* Do not redirect all edges. */,
1326 then_scale
, else_scale
);
1328 /* loopify redirected latch_edge. Update its PENDING_STMTS. */
1329 lv_flush_pending_stmts (latch_edge
);
1331 /* loopify redirected condition_bb's succ edge. Update its PENDING_STMTS. */
1332 extract_cond_bb_edges (cond_bb
, &true_edge
, &false_edge
);
1333 lv_flush_pending_stmts (false_edge
);
1334 /* Adjust irreducible flag. */
1337 cond_bb
->flags
|= BB_IRREDUCIBLE_LOOP
;
1338 loop_preheader_edge (loop
)->flags
|= EDGE_IRREDUCIBLE_LOOP
;
1339 loop_preheader_edge (nloop
)->flags
|= EDGE_IRREDUCIBLE_LOOP
;
1340 single_pred_edge (cond_bb
)->flags
|= EDGE_IRREDUCIBLE_LOOP
;
1345 basic_block
*bbs
= get_loop_body_in_dom_order (nloop
), after
;
1348 after
= loop
->latch
;
1350 for (i
= 0; i
< nloop
->num_nodes
; i
++)
1352 move_block_after (bbs
[i
], after
);
1358 /* At this point condition_bb is loop predheader with two successors,
1359 first_head and second_head. Make sure that loop predheader has only
1361 split_edge (loop_preheader_edge (loop
));
1362 split_edge (loop_preheader_edge (nloop
));
1367 /* The structure of loops might have changed. Some loops might get removed
1368 (and their headers and latches were set to NULL), loop exists might get
1369 removed (thus the loop nesting may be wrong), and some blocks and edges
1370 were changed (so the information about bb --> loop mapping does not have
1371 to be correct). But still for the remaining loops the header dominates
1372 the latch, and loops did not get new subloobs (new loops might possibly
1373 get created, but we are not interested in them). Fix up the mess.
1375 If CHANGED_BBS is not NULL, basic blocks whose loop has changed are
1379 fix_loop_structure (bitmap changed_bbs
)
1382 struct loop
*loop
, *ploop
;
1384 bool record_exits
= false;
1385 struct loop
**superloop
= XNEWVEC (struct loop
*, number_of_loops ());
1387 gcc_assert (current_loops
->state
& LOOPS_HAVE_SIMPLE_LATCHES
);
1389 /* Remove the old bb -> loop mapping. Remember the depth of the blocks in
1390 the loop hierarchy, so that we can recognize blocks whose loop nesting
1391 relationship has changed. */
1395 bb
->aux
= (void *) (size_t) loop_depth (bb
->loop_father
);
1396 bb
->loop_father
= current_loops
->tree_root
;
1399 if (current_loops
->state
& LOOPS_HAVE_RECORDED_EXITS
)
1401 release_recorded_exits ();
1402 record_exits
= true;
1405 /* Remove the dead loops from structures. We start from the innermost
1406 loops, so that when we remove the loops, we know that the loops inside
1407 are preserved, and do not waste time relinking loops that will be
1409 FOR_EACH_LOOP (li
, loop
, LI_FROM_INNERMOST
)
1416 ploop
= loop
->inner
;
1417 flow_loop_tree_node_remove (ploop
);
1418 flow_loop_tree_node_add (loop_outer (loop
), ploop
);
1421 /* Remove the loop and free its data. */
1425 /* Rescan the bodies of loops, starting from the outermost ones. We assume
1426 that no optimization interchanges the order of the loops, i.e., it cannot
1427 happen that L1 was superloop of L2 before and it is subloop of L2 now
1428 (without explicitly updating loop information). At the same time, we also
1429 determine the new loop structure. */
1430 current_loops
->tree_root
->num_nodes
= n_basic_blocks
;
1431 FOR_EACH_LOOP (li
, loop
, 0)
1433 superloop
[loop
->num
] = loop
->header
->loop_father
;
1434 loop
->num_nodes
= flow_loop_nodes_find (loop
->header
, loop
);
1437 /* Now fix the loop nesting. */
1438 FOR_EACH_LOOP (li
, loop
, 0)
1440 ploop
= superloop
[loop
->num
];
1441 if (ploop
!= loop_outer (loop
))
1443 flow_loop_tree_node_remove (loop
);
1444 flow_loop_tree_node_add (ploop
, loop
);
1449 /* Mark the blocks whose loop has changed. */
1454 if ((void *) (size_t) loop_depth (bb
->loop_father
) != bb
->aux
)
1455 bitmap_set_bit (changed_bbs
, bb
->index
);
1461 if (current_loops
->state
& LOOPS_HAVE_PREHEADERS
)
1462 create_preheaders (CP_SIMPLE_PREHEADERS
);
1464 if (current_loops
->state
& LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS
)
1465 mark_irreducible_loops ();
1468 record_loop_exits ();
1470 #ifdef ENABLE_CHECKING
1471 verify_loop_structure ();