1 /* Loop manipulation code for GNU compiler.
2 Copyright (C) 2002, 2003, 2004, 2005, 2007, 2008, 2009 Free Software
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
9 Software Foundation; either version 3, or (at your option) any later
12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING3. If not see
19 <http://www.gnu.org/licenses/>. */
23 #include "coretypes.h"
26 #include "hard-reg-set.h"
28 #include "basic-block.h"
30 #include "cfglayout.h"
33 #include "tree-flow.h"
35 static void copy_loops_to (struct loop
**, int,
37 static void loop_redirect_edge (edge
, basic_block
);
38 static void remove_bbs (basic_block
*, int);
39 static bool rpe_enum_p (const_basic_block
, const void *);
40 static int find_path (edge
, basic_block
**);
41 static void fix_loop_placements (struct loop
*, bool *);
42 static bool fix_bb_placement (basic_block
);
43 static void fix_bb_placements (basic_block
, bool *);
44 static void unloop (struct loop
*, bool *);
46 #define RDIV(X,Y) (((X) + (Y) / 2) / (Y))
48 /* Checks whether basic block BB is dominated by DATA. */
50 rpe_enum_p (const_basic_block bb
, const void *data
)
52 return dominated_by_p (CDI_DOMINATORS
, bb
, (const_basic_block
) data
);
55 /* Remove basic blocks BBS. NBBS is the number of the basic blocks. */
58 remove_bbs (basic_block
*bbs
, int nbbs
)
62 for (i
= 0; i
< nbbs
; i
++)
63 delete_basic_block (bbs
[i
]);
66 /* Find path -- i.e. the basic blocks dominated by edge E and put them
67 into array BBS, that will be allocated large enough to contain them.
68 E->dest must have exactly one predecessor for this to work (it is
69 easy to achieve and we do not put it here because we do not want to
70 alter anything by this function). The number of basic blocks in the
73 find_path (edge e
, basic_block
**bbs
)
75 gcc_assert (EDGE_COUNT (e
->dest
->preds
) <= 1);
77 /* Find bbs in the path. */
78 *bbs
= XCNEWVEC (basic_block
, n_basic_blocks
);
79 return dfs_enumerate_from (e
->dest
, 0, rpe_enum_p
, *bbs
,
80 n_basic_blocks
, e
->dest
);
83 /* Fix placement of basic block BB inside loop hierarchy --
84 Let L be a loop to that BB belongs. Then every successor of BB must either
85 1) belong to some superloop of loop L, or
86 2) be a header of loop K such that K->outer is superloop of L
87 Returns true if we had to move BB into other loop to enforce this condition,
88 false if the placement of BB was already correct (provided that placements
89 of its successors are correct). */
91 fix_bb_placement (basic_block bb
)
95 struct loop
*loop
= current_loops
->tree_root
, *act
;
97 FOR_EACH_EDGE (e
, ei
, bb
->succs
)
99 if (e
->dest
== EXIT_BLOCK_PTR
)
102 act
= e
->dest
->loop_father
;
103 if (act
->header
== e
->dest
)
104 act
= loop_outer (act
);
106 if (flow_loop_nested_p (loop
, act
))
110 if (loop
== bb
->loop_father
)
113 remove_bb_from_loops (bb
);
114 add_bb_to_loop (bb
, loop
);
119 /* Fix placement of LOOP inside loop tree, i.e. find the innermost superloop
120 of LOOP to that leads at least one exit edge of LOOP, and set it
121 as the immediate superloop of LOOP. Return true if the immediate superloop
125 fix_loop_placement (struct loop
*loop
)
129 VEC (edge
, heap
) *exits
= get_loop_exit_edges (loop
);
130 struct loop
*father
= current_loops
->tree_root
, *act
;
133 for (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 for (i
= 0; i
< nreml
; i
++)
352 cancel_loop_tree (deleted_loop
[i
]);
355 remove_bbs (rem_bbs
, nrem
);
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 && loops_state_satisfies_p (LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS
))
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
;
417 /* Add it to loop structure. */
418 place_new_loop (loop
);
419 flow_loop_tree_node_add (outer
, loop
);
421 /* Find its nodes. */
422 bbs
= XNEWVEC (basic_block
, n_basic_blocks
);
423 n
= get_loop_body_with_size (loop
, bbs
, n_basic_blocks
);
425 for (i
= 0; i
< n
; i
++)
427 if (bbs
[i
]->loop_father
== outer
)
429 remove_bb_from_loops (bbs
[i
]);
430 add_bb_to_loop (bbs
[i
], loop
);
436 /* If we find a direct subloop of OUTER, move it to LOOP. */
437 subloop
= bbs
[i
]->loop_father
;
438 if (loop_outer (subloop
) == outer
439 && subloop
->header
== bbs
[i
])
441 flow_loop_tree_node_remove (subloop
);
442 flow_loop_tree_node_add (loop
, subloop
);
446 /* Update the information about loop exit edges. */
447 for (i
= 0; i
< n
; i
++)
449 FOR_EACH_EDGE (e
, ei
, bbs
[i
]->succs
)
451 rescan_loop_exit (e
, false, false);
458 /* Multiply all frequencies in LOOP by NUM/DEN. */
460 scale_loop_frequencies (struct loop
*loop
, int num
, int den
)
464 bbs
= get_loop_body (loop
);
465 scale_bbs_frequencies_int (bbs
, loop
->num_nodes
, num
, den
);
469 /* Recompute dominance information for basic blocks outside LOOP. */
472 update_dominators_in_loop (struct loop
*loop
)
474 VEC (basic_block
, heap
) *dom_bbs
= NULL
;
479 seen
= sbitmap_alloc (last_basic_block
);
481 body
= get_loop_body (loop
);
483 for (i
= 0; i
< loop
->num_nodes
; i
++)
484 SET_BIT (seen
, body
[i
]->index
);
486 for (i
= 0; i
< loop
->num_nodes
; i
++)
490 for (ldom
= first_dom_son (CDI_DOMINATORS
, body
[i
]);
492 ldom
= next_dom_son (CDI_DOMINATORS
, ldom
))
493 if (!TEST_BIT (seen
, ldom
->index
))
495 SET_BIT (seen
, ldom
->index
);
496 VEC_safe_push (basic_block
, heap
, dom_bbs
, ldom
);
500 iterate_fix_dominators (CDI_DOMINATORS
, dom_bbs
, false);
503 VEC_free (basic_block
, heap
, dom_bbs
);
506 /* Creates an if region as shown above. CONDITION is used to create
510 | ------------- -------------
511 | | pred_bb | | pred_bb |
512 | ------------- -------------
516 | | ====> -------------
521 | ------------- e_false / \ e_true
523 | ------------- ----------- -----------
524 | | false_bb | | true_bb |
525 | ----------- -----------
532 | | exit_edge (result)
541 create_empty_if_region_on_edge (edge entry_edge
, tree condition
)
544 basic_block cond_bb
, true_bb
, false_bb
, join_bb
;
545 edge e_true
, e_false
, exit_edge
;
548 gimple_stmt_iterator gsi
;
550 cond_bb
= split_edge (entry_edge
);
552 /* Insert condition in cond_bb. */
553 gsi
= gsi_last_bb (cond_bb
);
555 force_gimple_operand_gsi (&gsi
, condition
, true, NULL
,
556 false, GSI_NEW_STMT
);
557 cond_stmt
= gimple_build_cond_from_tree (simple_cond
, NULL_TREE
, NULL_TREE
);
558 gsi
= gsi_last_bb (cond_bb
);
559 gsi_insert_after (&gsi
, cond_stmt
, GSI_NEW_STMT
);
561 join_bb
= split_edge (single_succ_edge (cond_bb
));
563 e_true
= single_succ_edge (cond_bb
);
564 true_bb
= split_edge (e_true
);
566 e_false
= make_edge (cond_bb
, join_bb
, 0);
567 false_bb
= split_edge (e_false
);
569 e_true
->flags
&= ~EDGE_FALLTHRU
;
570 e_true
->flags
|= EDGE_TRUE_VALUE
;
571 e_false
->flags
&= ~EDGE_FALLTHRU
;
572 e_false
->flags
|= EDGE_FALSE_VALUE
;
574 set_immediate_dominator (CDI_DOMINATORS
, cond_bb
, entry_edge
->src
);
575 set_immediate_dominator (CDI_DOMINATORS
, true_bb
, cond_bb
);
576 set_immediate_dominator (CDI_DOMINATORS
, false_bb
, cond_bb
);
577 set_immediate_dominator (CDI_DOMINATORS
, join_bb
, cond_bb
);
579 exit_edge
= single_succ_edge (join_bb
);
581 if (single_pred_p (exit_edge
->dest
))
582 set_immediate_dominator (CDI_DOMINATORS
, exit_edge
->dest
, join_bb
);
587 /* create_empty_loop_on_edge
589 | - pred_bb - ------ pred_bb ------
590 | | | | iv0 = initial_value |
591 | -----|----- ---------|-----------
592 | | ______ | entry_edge
594 | | ====> | -V---V- loop_header -------------
595 | V | | iv_before = phi (iv0, iv_after) |
596 | - succ_bb - | ---|-----------------------------
598 | ----------- | ---V--- loop_body ---------------
599 | | | iv_after = iv_before + stride |
600 | | | if (iv_before < upper_bound) |
601 | | ---|--------------\--------------
604 | | - loop_latch - V- succ_bb -
606 | | /------------- -----------
609 Creates an empty loop as shown above, the IV_BEFORE is the SSA_NAME
610 that is used before the increment of IV. IV_BEFORE should be used for
611 adding code to the body that uses the IV. OUTER is the outer loop in
612 which the new loop should be inserted.
614 Both INITIAL_VALUE and UPPER_BOUND expressions are gimplified and
615 inserted on the loop entry edge. This implies that this function
616 should be used only when the UPPER_BOUND expression is a loop
620 create_empty_loop_on_edge (edge entry_edge
,
622 tree stride
, tree upper_bound
,
628 basic_block loop_header
, loop_latch
, succ_bb
, pred_bb
;
630 gimple_stmt_iterator gsi
;
637 gcc_assert (entry_edge
&& initial_value
&& stride
&& upper_bound
&& iv
);
639 /* Create header, latch and wire up the loop. */
640 pred_bb
= entry_edge
->src
;
641 loop_header
= split_edge (entry_edge
);
642 loop_latch
= split_edge (single_succ_edge (loop_header
));
643 succ_bb
= single_succ (loop_latch
);
644 make_edge (loop_header
, succ_bb
, 0);
645 redirect_edge_succ_nodup (single_succ_edge (loop_latch
), loop_header
);
647 /* Set immediate dominator information. */
648 set_immediate_dominator (CDI_DOMINATORS
, loop_header
, pred_bb
);
649 set_immediate_dominator (CDI_DOMINATORS
, loop_latch
, loop_header
);
650 set_immediate_dominator (CDI_DOMINATORS
, succ_bb
, loop_header
);
652 /* Initialize a loop structure and put it in a loop hierarchy. */
653 loop
= alloc_loop ();
654 loop
->header
= loop_header
;
655 loop
->latch
= loop_latch
;
656 add_loop (loop
, outer
);
658 /* TODO: Fix frequencies and counts. */
659 prob
= REG_BR_PROB_BASE
/ 2;
661 scale_loop_frequencies (loop
, REG_BR_PROB_BASE
- prob
, REG_BR_PROB_BASE
);
663 /* Update dominators. */
664 update_dominators_in_loop (loop
);
666 /* Modify edge flags. */
667 exit_e
= single_exit (loop
);
668 exit_e
->flags
= EDGE_LOOP_EXIT
| EDGE_FALSE_VALUE
;
669 single_pred_edge (loop_latch
)->flags
= EDGE_TRUE_VALUE
;
671 /* Construct IV code in loop. */
672 initial_value
= force_gimple_operand (initial_value
, &stmts
, true, iv
);
675 gsi_insert_seq_on_edge (loop_preheader_edge (loop
), stmts
);
676 gsi_commit_edge_inserts ();
679 upper_bound
= force_gimple_operand (upper_bound
, &stmts
, true, NULL
);
682 gsi_insert_seq_on_edge (loop_preheader_edge (loop
), stmts
);
683 gsi_commit_edge_inserts ();
686 gsi
= gsi_last_bb (loop_header
);
687 create_iv (initial_value
, stride
, iv
, loop
, &gsi
, false,
688 iv_before
, iv_after
);
690 /* Insert loop exit condition. */
691 cond_expr
= gimple_build_cond
692 (LT_EXPR
, *iv_before
, upper_bound
, NULL_TREE
, NULL_TREE
);
694 exit_test
= gimple_cond_lhs (cond_expr
);
695 exit_test
= force_gimple_operand_gsi (&gsi
, exit_test
, true, NULL
,
696 false, GSI_NEW_STMT
);
697 gimple_cond_set_lhs (cond_expr
, exit_test
);
698 gsi
= gsi_last_bb (exit_e
->src
);
699 gsi_insert_after (&gsi
, cond_expr
, GSI_NEW_STMT
);
701 split_block_after_labels (loop_header
);
706 /* Make area between HEADER_EDGE and LATCH_EDGE a loop by connecting
707 latch to header and update loop tree and dominators
708 accordingly. Everything between them plus LATCH_EDGE destination must
709 be dominated by HEADER_EDGE destination, and back-reachable from
710 LATCH_EDGE source. HEADER_EDGE is redirected to basic block SWITCH_BB,
711 FALSE_EDGE of SWITCH_BB to original destination of HEADER_EDGE and
712 TRUE_EDGE of SWITCH_BB to original destination of LATCH_EDGE.
713 Returns the newly created loop. Frequencies and counts in the new loop
714 are scaled by FALSE_SCALE and in the old one by TRUE_SCALE. */
717 loopify (edge latch_edge
, edge header_edge
,
718 basic_block switch_bb
, edge true_edge
, edge false_edge
,
719 bool redirect_all_edges
, unsigned true_scale
, unsigned false_scale
)
721 basic_block succ_bb
= latch_edge
->dest
;
722 basic_block pred_bb
= header_edge
->src
;
723 struct loop
*loop
= alloc_loop ();
724 struct loop
*outer
= loop_outer (succ_bb
->loop_father
);
730 loop
->header
= header_edge
->dest
;
731 loop
->latch
= latch_edge
->src
;
733 freq
= EDGE_FREQUENCY (header_edge
);
734 cnt
= header_edge
->count
;
736 /* Redirect edges. */
737 loop_redirect_edge (latch_edge
, loop
->header
);
738 loop_redirect_edge (true_edge
, succ_bb
);
740 /* During loop versioning, one of the switch_bb edge is already properly
741 set. Do not redirect it again unless redirect_all_edges is true. */
742 if (redirect_all_edges
)
744 loop_redirect_edge (header_edge
, switch_bb
);
745 loop_redirect_edge (false_edge
, loop
->header
);
747 /* Update dominators. */
748 set_immediate_dominator (CDI_DOMINATORS
, switch_bb
, pred_bb
);
749 set_immediate_dominator (CDI_DOMINATORS
, loop
->header
, switch_bb
);
752 set_immediate_dominator (CDI_DOMINATORS
, succ_bb
, switch_bb
);
754 /* Compute new loop. */
755 add_loop (loop
, outer
);
757 /* Add switch_bb to appropriate loop. */
758 if (switch_bb
->loop_father
)
759 remove_bb_from_loops (switch_bb
);
760 add_bb_to_loop (switch_bb
, outer
);
762 /* Fix frequencies. */
763 if (redirect_all_edges
)
765 switch_bb
->frequency
= freq
;
766 switch_bb
->count
= cnt
;
767 FOR_EACH_EDGE (e
, ei
, switch_bb
->succs
)
769 e
->count
= (switch_bb
->count
* e
->probability
) / REG_BR_PROB_BASE
;
772 scale_loop_frequencies (loop
, false_scale
, REG_BR_PROB_BASE
);
773 scale_loop_frequencies (succ_bb
->loop_father
, true_scale
, REG_BR_PROB_BASE
);
774 update_dominators_in_loop (loop
);
779 /* Remove the latch edge of a LOOP and update loops to indicate that
780 the LOOP was removed. After this function, original loop latch will
781 have no successor, which caller is expected to fix somehow.
783 If this may cause the information about irreducible regions to become
784 invalid, IRRED_INVALIDATED is set to true. */
787 unloop (struct loop
*loop
, bool *irred_invalidated
)
792 basic_block latch
= loop
->latch
;
795 if (loop_preheader_edge (loop
)->flags
& EDGE_IRREDUCIBLE_LOOP
)
796 *irred_invalidated
= true;
798 /* This is relatively straightforward. The dominators are unchanged, as
799 loop header dominates loop latch, so the only thing we have to care of
800 is the placement of loops and basic blocks inside the loop tree. We
801 move them all to the loop->outer, and then let fix_bb_placements do
804 body
= get_loop_body (loop
);
806 for (i
= 0; i
< n
; i
++)
807 if (body
[i
]->loop_father
== loop
)
809 remove_bb_from_loops (body
[i
]);
810 add_bb_to_loop (body
[i
], loop_outer (loop
));
817 flow_loop_tree_node_remove (ploop
);
818 flow_loop_tree_node_add (loop_outer (loop
), ploop
);
821 /* Remove the loop and free its data. */
824 remove_edge (single_succ_edge (latch
));
826 /* We do not pass IRRED_INVALIDATED to fix_bb_placements here, as even if
827 there is an irreducible region inside the cancelled loop, the flags will
829 fix_bb_placements (latch
, &dummy
);
832 /* Fix placement of superloops of LOOP inside loop tree, i.e. ensure that
833 condition stated in description of fix_loop_placement holds for them.
834 It is used in case when we removed some edges coming out of LOOP, which
835 may cause the right placement of LOOP inside loop tree to change.
837 IRRED_INVALIDATED is set to true if a change in the loop structures might
838 invalidate the information about irreducible regions. */
841 fix_loop_placements (struct loop
*loop
, bool *irred_invalidated
)
845 while (loop_outer (loop
))
847 outer
= loop_outer (loop
);
848 if (!fix_loop_placement (loop
))
851 /* Changing the placement of a loop in the loop tree may alter the
852 validity of condition 2) of the description of fix_bb_placement
853 for its preheader, because the successor is the header and belongs
854 to the loop. So call fix_bb_placements to fix up the placement
855 of the preheader and (possibly) of its predecessors. */
856 fix_bb_placements (loop_preheader_edge (loop
)->src
,
862 /* Copies copy of LOOP as subloop of TARGET loop, placing newly
863 created loop into loops structure. */
865 duplicate_loop (struct loop
*loop
, struct loop
*target
)
868 cloop
= alloc_loop ();
869 place_new_loop (cloop
);
871 /* Mark the new loop as copy of LOOP. */
872 set_loop_copy (loop
, cloop
);
874 /* Add it to target. */
875 flow_loop_tree_node_add (target
, cloop
);
880 /* Copies structure of subloops of LOOP into TARGET loop, placing
881 newly created loops into loop tree. */
883 duplicate_subloops (struct loop
*loop
, struct loop
*target
)
885 struct loop
*aloop
, *cloop
;
887 for (aloop
= loop
->inner
; aloop
; aloop
= aloop
->next
)
889 cloop
= duplicate_loop (aloop
, target
);
890 duplicate_subloops (aloop
, cloop
);
894 /* Copies structure of subloops of N loops, stored in array COPIED_LOOPS,
895 into TARGET loop, placing newly created loops into loop tree. */
897 copy_loops_to (struct loop
**copied_loops
, int n
, struct loop
*target
)
902 for (i
= 0; i
< n
; i
++)
904 aloop
= duplicate_loop (copied_loops
[i
], target
);
905 duplicate_subloops (copied_loops
[i
], aloop
);
909 /* Redirects edge E to basic block DEST. */
911 loop_redirect_edge (edge e
, basic_block dest
)
916 redirect_edge_and_branch_force (e
, dest
);
919 /* Check whether LOOP's body can be duplicated. */
921 can_duplicate_loop_p (const struct loop
*loop
)
924 basic_block
*bbs
= get_loop_body (loop
);
926 ret
= can_copy_bbs_p (bbs
, loop
->num_nodes
);
932 /* Sets probability and count of edge E to zero. The probability and count
933 is redistributed evenly to the remaining edges coming from E->src. */
936 set_zero_probability (edge e
)
938 basic_block bb
= e
->src
;
940 edge ae
, last
= NULL
;
941 unsigned n
= EDGE_COUNT (bb
->succs
);
942 gcov_type cnt
= e
->count
, cnt1
;
943 unsigned prob
= e
->probability
, prob1
;
946 cnt1
= cnt
/ (n
- 1);
947 prob1
= prob
/ (n
- 1);
949 FOR_EACH_EDGE (ae
, ei
, bb
->succs
)
954 ae
->probability
+= prob1
;
959 /* Move the rest to one of the edges. */
960 last
->probability
+= prob
% (n
- 1);
961 last
->count
+= cnt
% (n
- 1);
967 /* Duplicates body of LOOP to given edge E NDUPL times. Takes care of updating
968 loop structure and dominators. E's destination must be LOOP header for
969 this to work, i.e. it must be entry or latch edge of this loop; these are
970 unique, as the loops must have preheaders for this function to work
971 correctly (in case E is latch, the function unrolls the loop, if E is entry
972 edge, it peels the loop). Store edges created by copying ORIG edge from
973 copies corresponding to set bits in WONT_EXIT bitmap (bit 0 corresponds to
974 original LOOP body, the other copies are numbered in order given by control
975 flow through them) into TO_REMOVE array. Returns false if duplication is
979 duplicate_loop_to_header_edge (struct loop
*loop
, edge e
,
980 unsigned int ndupl
, sbitmap wont_exit
,
981 edge orig
, VEC (edge
, heap
) **to_remove
,
984 struct loop
*target
, *aloop
;
985 struct loop
**orig_loops
;
986 unsigned n_orig_loops
;
987 basic_block header
= loop
->header
, latch
= loop
->latch
;
988 basic_block
*new_bbs
, *bbs
, *first_active
;
989 basic_block new_bb
, bb
, first_active_latch
= NULL
;
991 edge spec_edges
[2], new_spec_edges
[2];
995 int is_latch
= (latch
== e
->src
);
996 int scale_act
= 0, *scale_step
= NULL
, scale_main
= 0;
997 int scale_after_exit
= 0;
998 int p
, freq_in
, freq_le
, freq_out_orig
;
999 int prob_pass_thru
, prob_pass_wont_exit
, prob_pass_main
;
1000 int add_irreducible_flag
;
1001 basic_block place_after
;
1002 bitmap bbs_to_scale
= NULL
;
1005 gcc_assert (e
->dest
== loop
->header
);
1006 gcc_assert (ndupl
> 0);
1010 /* Orig must be edge out of the loop. */
1011 gcc_assert (flow_bb_inside_loop_p (loop
, orig
->src
));
1012 gcc_assert (!flow_bb_inside_loop_p (loop
, orig
->dest
));
1015 n
= loop
->num_nodes
;
1016 bbs
= get_loop_body_in_dom_order (loop
);
1017 gcc_assert (bbs
[0] == loop
->header
);
1018 gcc_assert (bbs
[n
- 1] == loop
->latch
);
1020 /* Check whether duplication is possible. */
1021 if (!can_copy_bbs_p (bbs
, loop
->num_nodes
))
1026 new_bbs
= XNEWVEC (basic_block
, loop
->num_nodes
);
1028 /* In case we are doing loop peeling and the loop is in the middle of
1029 irreducible region, the peeled copies will be inside it too. */
1030 add_irreducible_flag
= e
->flags
& EDGE_IRREDUCIBLE_LOOP
;
1031 gcc_assert (!is_latch
|| !add_irreducible_flag
);
1033 /* Find edge from latch. */
1034 latch_edge
= loop_latch_edge (loop
);
1036 if (flags
& DLTHE_FLAG_UPDATE_FREQ
)
1038 /* Calculate coefficients by that we have to scale frequencies
1039 of duplicated loop bodies. */
1040 freq_in
= header
->frequency
;
1041 freq_le
= EDGE_FREQUENCY (latch_edge
);
1044 if (freq_in
< freq_le
)
1046 freq_out_orig
= orig
? EDGE_FREQUENCY (orig
) : freq_in
- freq_le
;
1047 if (freq_out_orig
> freq_in
- freq_le
)
1048 freq_out_orig
= freq_in
- freq_le
;
1049 prob_pass_thru
= RDIV (REG_BR_PROB_BASE
* freq_le
, freq_in
);
1050 prob_pass_wont_exit
=
1051 RDIV (REG_BR_PROB_BASE
* (freq_le
+ freq_out_orig
), freq_in
);
1054 && REG_BR_PROB_BASE
- orig
->probability
!= 0)
1056 /* The blocks that are dominated by a removed exit edge ORIG have
1057 frequencies scaled by this. */
1058 scale_after_exit
= RDIV (REG_BR_PROB_BASE
* REG_BR_PROB_BASE
,
1059 REG_BR_PROB_BASE
- orig
->probability
);
1060 bbs_to_scale
= BITMAP_ALLOC (NULL
);
1061 for (i
= 0; i
< n
; i
++)
1063 if (bbs
[i
] != orig
->src
1064 && dominated_by_p (CDI_DOMINATORS
, bbs
[i
], orig
->src
))
1065 bitmap_set_bit (bbs_to_scale
, i
);
1069 scale_step
= XNEWVEC (int, ndupl
);
1071 for (i
= 1; i
<= ndupl
; i
++)
1072 scale_step
[i
- 1] = TEST_BIT (wont_exit
, i
)
1073 ? prob_pass_wont_exit
1076 /* Complete peeling is special as the probability of exit in last
1078 if (flags
& DLTHE_FLAG_COMPLETTE_PEEL
)
1080 int wanted_freq
= EDGE_FREQUENCY (e
);
1082 if (wanted_freq
> freq_in
)
1083 wanted_freq
= freq_in
;
1085 gcc_assert (!is_latch
);
1086 /* First copy has frequency of incoming edge. Each subsequent
1087 frequency should be reduced by prob_pass_wont_exit. Caller
1088 should've managed the flags so all except for original loop
1089 has won't exist set. */
1090 scale_act
= RDIV (wanted_freq
* REG_BR_PROB_BASE
, freq_in
);
1091 /* Now simulate the duplication adjustments and compute header
1092 frequency of the last copy. */
1093 for (i
= 0; i
< ndupl
; i
++)
1094 wanted_freq
= RDIV (wanted_freq
* scale_step
[i
], REG_BR_PROB_BASE
);
1095 scale_main
= RDIV (wanted_freq
* REG_BR_PROB_BASE
, freq_in
);
1099 prob_pass_main
= TEST_BIT (wont_exit
, 0)
1100 ? prob_pass_wont_exit
1103 scale_main
= REG_BR_PROB_BASE
;
1104 for (i
= 0; i
< ndupl
; i
++)
1107 p
= RDIV (p
* scale_step
[i
], REG_BR_PROB_BASE
);
1109 scale_main
= RDIV (REG_BR_PROB_BASE
* REG_BR_PROB_BASE
, scale_main
);
1110 scale_act
= RDIV (scale_main
* prob_pass_main
, REG_BR_PROB_BASE
);
1114 scale_main
= REG_BR_PROB_BASE
;
1115 for (i
= 0; i
< ndupl
; i
++)
1116 scale_main
= RDIV (scale_main
* scale_step
[i
], REG_BR_PROB_BASE
);
1117 scale_act
= REG_BR_PROB_BASE
- prob_pass_thru
;
1119 for (i
= 0; i
< ndupl
; i
++)
1120 gcc_assert (scale_step
[i
] >= 0 && scale_step
[i
] <= REG_BR_PROB_BASE
);
1121 gcc_assert (scale_main
>= 0 && scale_main
<= REG_BR_PROB_BASE
1122 && scale_act
>= 0 && scale_act
<= REG_BR_PROB_BASE
);
1125 /* Loop the new bbs will belong to. */
1126 target
= e
->src
->loop_father
;
1128 /* Original loops. */
1130 for (aloop
= loop
->inner
; aloop
; aloop
= aloop
->next
)
1132 orig_loops
= XCNEWVEC (struct loop
*, n_orig_loops
);
1133 for (aloop
= loop
->inner
, i
= 0; aloop
; aloop
= aloop
->next
, i
++)
1134 orig_loops
[i
] = aloop
;
1136 set_loop_copy (loop
, target
);
1138 first_active
= XNEWVEC (basic_block
, n
);
1141 memcpy (first_active
, bbs
, n
* sizeof (basic_block
));
1142 first_active_latch
= latch
;
1145 spec_edges
[SE_ORIG
] = orig
;
1146 spec_edges
[SE_LATCH
] = latch_edge
;
1148 place_after
= e
->src
;
1149 for (j
= 0; j
< ndupl
; j
++)
1152 copy_loops_to (orig_loops
, n_orig_loops
, target
);
1155 copy_bbs (bbs
, n
, new_bbs
, spec_edges
, 2, new_spec_edges
, loop
,
1157 place_after
= new_spec_edges
[SE_LATCH
]->src
;
1159 if (flags
& DLTHE_RECORD_COPY_NUMBER
)
1160 for (i
= 0; i
< n
; i
++)
1162 gcc_assert (!new_bbs
[i
]->aux
);
1163 new_bbs
[i
]->aux
= (void *)(size_t)(j
+ 1);
1166 /* Note whether the blocks and edges belong to an irreducible loop. */
1167 if (add_irreducible_flag
)
1169 for (i
= 0; i
< n
; i
++)
1170 new_bbs
[i
]->flags
|= BB_DUPLICATED
;
1171 for (i
= 0; i
< n
; i
++)
1174 new_bb
= new_bbs
[i
];
1175 if (new_bb
->loop_father
== target
)
1176 new_bb
->flags
|= BB_IRREDUCIBLE_LOOP
;
1178 FOR_EACH_EDGE (ae
, ei
, new_bb
->succs
)
1179 if ((ae
->dest
->flags
& BB_DUPLICATED
)
1180 && (ae
->src
->loop_father
== target
1181 || ae
->dest
->loop_father
== target
))
1182 ae
->flags
|= EDGE_IRREDUCIBLE_LOOP
;
1184 for (i
= 0; i
< n
; i
++)
1185 new_bbs
[i
]->flags
&= ~BB_DUPLICATED
;
1188 /* Redirect the special edges. */
1191 redirect_edge_and_branch_force (latch_edge
, new_bbs
[0]);
1192 redirect_edge_and_branch_force (new_spec_edges
[SE_LATCH
],
1194 set_immediate_dominator (CDI_DOMINATORS
, new_bbs
[0], latch
);
1195 latch
= loop
->latch
= new_bbs
[n
- 1];
1196 e
= latch_edge
= new_spec_edges
[SE_LATCH
];
1200 redirect_edge_and_branch_force (new_spec_edges
[SE_LATCH
],
1202 redirect_edge_and_branch_force (e
, new_bbs
[0]);
1203 set_immediate_dominator (CDI_DOMINATORS
, new_bbs
[0], e
->src
);
1204 e
= new_spec_edges
[SE_LATCH
];
1207 /* Record exit edge in this copy. */
1208 if (orig
&& TEST_BIT (wont_exit
, j
+ 1))
1211 VEC_safe_push (edge
, heap
, *to_remove
, new_spec_edges
[SE_ORIG
]);
1212 set_zero_probability (new_spec_edges
[SE_ORIG
]);
1214 /* Scale the frequencies of the blocks dominated by the exit. */
1217 EXECUTE_IF_SET_IN_BITMAP (bbs_to_scale
, 0, i
, bi
)
1219 scale_bbs_frequencies_int (new_bbs
+ i
, 1, scale_after_exit
,
1225 /* Record the first copy in the control flow order if it is not
1226 the original loop (i.e. in case of peeling). */
1227 if (!first_active_latch
)
1229 memcpy (first_active
, new_bbs
, n
* sizeof (basic_block
));
1230 first_active_latch
= new_bbs
[n
- 1];
1233 /* Set counts and frequencies. */
1234 if (flags
& DLTHE_FLAG_UPDATE_FREQ
)
1236 scale_bbs_frequencies_int (new_bbs
, n
, scale_act
, REG_BR_PROB_BASE
);
1237 scale_act
= RDIV (scale_act
* scale_step
[j
], REG_BR_PROB_BASE
);
1243 /* Record the exit edge in the original loop body, and update the frequencies. */
1244 if (orig
&& TEST_BIT (wont_exit
, 0))
1247 VEC_safe_push (edge
, heap
, *to_remove
, orig
);
1248 set_zero_probability (orig
);
1250 /* Scale the frequencies of the blocks dominated by the exit. */
1253 EXECUTE_IF_SET_IN_BITMAP (bbs_to_scale
, 0, i
, bi
)
1255 scale_bbs_frequencies_int (bbs
+ i
, 1, scale_after_exit
,
1261 /* Update the original loop. */
1263 set_immediate_dominator (CDI_DOMINATORS
, e
->dest
, e
->src
);
1264 if (flags
& DLTHE_FLAG_UPDATE_FREQ
)
1266 scale_bbs_frequencies_int (bbs
, n
, scale_main
, REG_BR_PROB_BASE
);
1270 /* Update dominators of outer blocks if affected. */
1271 for (i
= 0; i
< n
; i
++)
1273 basic_block dominated
, dom_bb
;
1274 VEC (basic_block
, heap
) *dom_bbs
;
1280 dom_bbs
= get_dominated_by (CDI_DOMINATORS
, bb
);
1281 for (j
= 0; VEC_iterate (basic_block
, dom_bbs
, j
, dominated
); j
++)
1283 if (flow_bb_inside_loop_p (loop
, dominated
))
1285 dom_bb
= nearest_common_dominator (
1286 CDI_DOMINATORS
, first_active
[i
], first_active_latch
);
1287 set_immediate_dominator (CDI_DOMINATORS
, dominated
, dom_bb
);
1289 VEC_free (basic_block
, heap
, dom_bbs
);
1291 free (first_active
);
1294 BITMAP_FREE (bbs_to_scale
);
1299 /* A callback for make_forwarder block, to redirect all edges except for
1300 MFB_KJ_EDGE to the entry part. E is the edge for that we should decide
1301 whether to redirect it. */
1305 mfb_keep_just (edge e
)
1307 return e
!= mfb_kj_edge
;
1310 /* True when a candidate preheader BLOCK has predecessors from LOOP. */
1313 has_preds_from_loop (basic_block block
, struct loop
*loop
)
1318 FOR_EACH_EDGE (e
, ei
, block
->preds
)
1319 if (e
->src
->loop_father
== loop
)
1324 /* Creates a pre-header for a LOOP. Returns newly created block. Unless
1325 CP_SIMPLE_PREHEADERS is set in FLAGS, we only force LOOP to have single
1326 entry; otherwise we also force preheader block to have only one successor.
1327 When CP_FALLTHRU_PREHEADERS is set in FLAGS, we force the preheader block
1328 to be a fallthru predecessor to the loop header and to have only
1329 predecessors from outside of the loop.
1330 The function also updates dominators. */
1333 create_preheader (struct loop
*loop
, int flags
)
1339 bool latch_edge_was_fallthru
;
1340 edge one_succ_pred
= NULL
, single_entry
= NULL
;
1343 FOR_EACH_EDGE (e
, ei
, loop
->header
->preds
)
1345 if (e
->src
== loop
->latch
)
1347 irred
|= (e
->flags
& EDGE_IRREDUCIBLE_LOOP
) != 0;
1350 if (single_succ_p (e
->src
))
1353 gcc_assert (nentry
);
1356 bool need_forwarder_block
= false;
1358 /* We do not allow entry block to be the loop preheader, since we
1359 cannot emit code there. */
1360 if (single_entry
->src
== ENTRY_BLOCK_PTR
)
1361 need_forwarder_block
= true;
1364 /* If we want simple preheaders, also force the preheader to have
1365 just a single successor. */
1366 if ((flags
& CP_SIMPLE_PREHEADERS
)
1367 && !single_succ_p (single_entry
->src
))
1368 need_forwarder_block
= true;
1369 /* If we want fallthru preheaders, also create forwarder block when
1370 preheader ends with a jump or has predecessors from loop. */
1371 else if ((flags
& CP_FALLTHRU_PREHEADERS
)
1372 && (JUMP_P (BB_END (single_entry
->src
))
1373 || has_preds_from_loop (single_entry
->src
, loop
)))
1374 need_forwarder_block
= true;
1376 if (! need_forwarder_block
)
1380 mfb_kj_edge
= loop_latch_edge (loop
);
1381 latch_edge_was_fallthru
= (mfb_kj_edge
->flags
& EDGE_FALLTHRU
) != 0;
1382 fallthru
= make_forwarder_block (loop
->header
, mfb_keep_just
, NULL
);
1383 dummy
= fallthru
->src
;
1384 loop
->header
= fallthru
->dest
;
1386 /* Try to be clever in placing the newly created preheader. The idea is to
1387 avoid breaking any "fallthruness" relationship between blocks.
1389 The preheader was created just before the header and all incoming edges
1390 to the header were redirected to the preheader, except the latch edge.
1391 So the only problematic case is when this latch edge was a fallthru
1392 edge: it is not anymore after the preheader creation so we have broken
1393 the fallthruness. We're therefore going to look for a better place. */
1394 if (latch_edge_was_fallthru
)
1399 e
= EDGE_PRED (dummy
, 0);
1401 move_block_after (dummy
, e
->src
);
1406 dummy
->flags
|= BB_IRREDUCIBLE_LOOP
;
1407 single_succ_edge (dummy
)->flags
|= EDGE_IRREDUCIBLE_LOOP
;
1411 fprintf (dump_file
, "Created preheader block for loop %i\n",
1414 if (flags
& CP_FALLTHRU_PREHEADERS
)
1415 gcc_assert ((single_succ_edge (dummy
)->flags
& EDGE_FALLTHRU
)
1416 && !JUMP_P (BB_END (dummy
)));
1421 /* Create preheaders for each loop; for meaning of FLAGS see create_preheader. */
1424 create_preheaders (int flags
)
1432 FOR_EACH_LOOP (li
, loop
, 0)
1433 create_preheader (loop
, flags
);
1434 loops_state_set (LOOPS_HAVE_PREHEADERS
);
1437 /* Forces all loop latches to have only single successor. */
1440 force_single_succ_latches (void)
1446 FOR_EACH_LOOP (li
, loop
, 0)
1448 if (loop
->latch
!= loop
->header
&& single_succ_p (loop
->latch
))
1451 e
= find_edge (loop
->latch
, loop
->header
);
1455 loops_state_set (LOOPS_HAVE_SIMPLE_LATCHES
);
1458 /* This function is called from loop_version. It splits the entry edge
1459 of the loop we want to version, adds the versioning condition, and
1460 adjust the edges to the two versions of the loop appropriately.
1461 e is an incoming edge. Returns the basic block containing the
1464 --- edge e ---- > [second_head]
1466 Split it and insert new conditional expression and adjust edges.
1468 --- edge e ---> [cond expr] ---> [first_head]
1470 +---------> [second_head]
1472 THEN_PROB is the probability of then branch of the condition. */
1475 lv_adjust_loop_entry_edge (basic_block first_head
, basic_block second_head
,
1476 edge e
, void *cond_expr
, unsigned then_prob
)
1478 basic_block new_head
= NULL
;
1481 gcc_assert (e
->dest
== second_head
);
1483 /* Split edge 'e'. This will create a new basic block, where we can
1484 insert conditional expr. */
1485 new_head
= split_edge (e
);
1487 lv_add_condition_to_bb (first_head
, second_head
, new_head
,
1490 /* Don't set EDGE_TRUE_VALUE in RTL mode, as it's invalid there. */
1491 e
= single_succ_edge (new_head
);
1492 e1
= make_edge (new_head
, first_head
,
1493 current_ir_type () == IR_GIMPLE
? EDGE_TRUE_VALUE
: 0);
1494 e1
->probability
= then_prob
;
1495 e
->probability
= REG_BR_PROB_BASE
- then_prob
;
1496 e1
->count
= RDIV (e
->count
* e1
->probability
, REG_BR_PROB_BASE
);
1497 e
->count
= RDIV (e
->count
* e
->probability
, REG_BR_PROB_BASE
);
1499 set_immediate_dominator (CDI_DOMINATORS
, first_head
, new_head
);
1500 set_immediate_dominator (CDI_DOMINATORS
, second_head
, new_head
);
1502 /* Adjust loop header phi nodes. */
1503 lv_adjust_loop_header_phi (first_head
, second_head
, new_head
, e1
);
1508 /* Main entry point for Loop Versioning transformation.
1510 This transformation given a condition and a loop, creates
1511 -if (condition) { loop_copy1 } else { loop_copy2 },
1512 where loop_copy1 is the loop transformed in one way, and loop_copy2
1513 is the loop transformed in another way (or unchanged). 'condition'
1514 may be a run time test for things that were not resolved by static
1515 analysis (overlapping ranges (anti-aliasing), alignment, etc.).
1517 THEN_PROB is the probability of the then edge of the if. THEN_SCALE
1518 is the ratio by that the frequencies in the original loop should
1519 be scaled. ELSE_SCALE is the ratio by that the frequencies in the
1520 new loop should be scaled.
1522 If PLACE_AFTER is true, we place the new loop after LOOP in the
1523 instruction stream, otherwise it is placed before LOOP. */
1526 loop_version (struct loop
*loop
,
1527 void *cond_expr
, basic_block
*condition_bb
,
1528 unsigned then_prob
, unsigned then_scale
, unsigned else_scale
,
1531 basic_block first_head
, second_head
;
1532 edge entry
, latch_edge
, true_edge
, false_edge
;
1535 basic_block cond_bb
;
1537 /* Record entry and latch edges for the loop */
1538 entry
= loop_preheader_edge (loop
);
1539 irred_flag
= entry
->flags
& EDGE_IRREDUCIBLE_LOOP
;
1540 entry
->flags
&= ~EDGE_IRREDUCIBLE_LOOP
;
1542 /* Note down head of loop as first_head. */
1543 first_head
= entry
->dest
;
1545 /* Duplicate loop. */
1546 if (!cfg_hook_duplicate_loop_to_header_edge (loop
, entry
, 1,
1547 NULL
, NULL
, NULL
, 0))
1550 /* After duplication entry edge now points to new loop head block.
1551 Note down new head as second_head. */
1552 second_head
= entry
->dest
;
1554 /* Split loop entry edge and insert new block with cond expr. */
1555 cond_bb
= lv_adjust_loop_entry_edge (first_head
, second_head
,
1556 entry
, cond_expr
, then_prob
);
1558 *condition_bb
= cond_bb
;
1562 entry
->flags
|= irred_flag
;
1566 latch_edge
= single_succ_edge (get_bb_copy (loop
->latch
));
1568 extract_cond_bb_edges (cond_bb
, &true_edge
, &false_edge
);
1569 nloop
= loopify (latch_edge
,
1570 single_pred_edge (get_bb_copy (loop
->header
)),
1571 cond_bb
, true_edge
, false_edge
,
1572 false /* Do not redirect all edges. */,
1573 then_scale
, else_scale
);
1575 /* loopify redirected latch_edge. Update its PENDING_STMTS. */
1576 lv_flush_pending_stmts (latch_edge
);
1578 /* loopify redirected condition_bb's succ edge. Update its PENDING_STMTS. */
1579 extract_cond_bb_edges (cond_bb
, &true_edge
, &false_edge
);
1580 lv_flush_pending_stmts (false_edge
);
1581 /* Adjust irreducible flag. */
1584 cond_bb
->flags
|= BB_IRREDUCIBLE_LOOP
;
1585 loop_preheader_edge (loop
)->flags
|= EDGE_IRREDUCIBLE_LOOP
;
1586 loop_preheader_edge (nloop
)->flags
|= EDGE_IRREDUCIBLE_LOOP
;
1587 single_pred_edge (cond_bb
)->flags
|= EDGE_IRREDUCIBLE_LOOP
;
1592 basic_block
*bbs
= get_loop_body_in_dom_order (nloop
), after
;
1595 after
= loop
->latch
;
1597 for (i
= 0; i
< nloop
->num_nodes
; i
++)
1599 move_block_after (bbs
[i
], after
);
1605 /* At this point condition_bb is loop preheader with two successors,
1606 first_head and second_head. Make sure that loop preheader has only
1608 split_edge (loop_preheader_edge (loop
));
1609 split_edge (loop_preheader_edge (nloop
));
1614 /* The structure of loops might have changed. Some loops might get removed
1615 (and their headers and latches were set to NULL), loop exists might get
1616 removed (thus the loop nesting may be wrong), and some blocks and edges
1617 were changed (so the information about bb --> loop mapping does not have
1618 to be correct). But still for the remaining loops the header dominates
1619 the latch, and loops did not get new subloops (new loops might possibly
1620 get created, but we are not interested in them). Fix up the mess.
1622 If CHANGED_BBS is not NULL, basic blocks whose loop has changed are
1626 fix_loop_structure (bitmap changed_bbs
)
1629 struct loop
*loop
, *ploop
;
1631 bool record_exits
= false;
1632 struct loop
**superloop
= XNEWVEC (struct loop
*, number_of_loops ());
1634 /* Remove the old bb -> loop mapping. Remember the depth of the blocks in
1635 the loop hierarchy, so that we can recognize blocks whose loop nesting
1636 relationship has changed. */
1640 bb
->aux
= (void *) (size_t) loop_depth (bb
->loop_father
);
1641 bb
->loop_father
= current_loops
->tree_root
;
1644 if (loops_state_satisfies_p (LOOPS_HAVE_RECORDED_EXITS
))
1646 release_recorded_exits ();
1647 record_exits
= true;
1650 /* Remove the dead loops from structures. We start from the innermost
1651 loops, so that when we remove the loops, we know that the loops inside
1652 are preserved, and do not waste time relinking loops that will be
1654 FOR_EACH_LOOP (li
, loop
, LI_FROM_INNERMOST
)
1661 ploop
= loop
->inner
;
1662 flow_loop_tree_node_remove (ploop
);
1663 flow_loop_tree_node_add (loop_outer (loop
), ploop
);
1666 /* Remove the loop and free its data. */
1670 /* Rescan the bodies of loops, starting from the outermost ones. We assume
1671 that no optimization interchanges the order of the loops, i.e., it cannot
1672 happen that L1 was superloop of L2 before and it is subloop of L2 now
1673 (without explicitly updating loop information). At the same time, we also
1674 determine the new loop structure. */
1675 current_loops
->tree_root
->num_nodes
= n_basic_blocks
;
1676 FOR_EACH_LOOP (li
, loop
, 0)
1678 superloop
[loop
->num
] = loop
->header
->loop_father
;
1679 loop
->num_nodes
= flow_loop_nodes_find (loop
->header
, loop
);
1682 /* Now fix the loop nesting. */
1683 FOR_EACH_LOOP (li
, loop
, 0)
1685 ploop
= superloop
[loop
->num
];
1686 if (ploop
!= loop_outer (loop
))
1688 flow_loop_tree_node_remove (loop
);
1689 flow_loop_tree_node_add (ploop
, loop
);
1694 /* Mark the blocks whose loop has changed. */
1699 if ((void *) (size_t) loop_depth (bb
->loop_father
) != bb
->aux
)
1700 bitmap_set_bit (changed_bbs
, bb
->index
);
1706 if (loops_state_satisfies_p (LOOPS_HAVE_PREHEADERS
))
1707 create_preheaders (CP_SIMPLE_PREHEADERS
);
1709 if (loops_state_satisfies_p (LOOPS_HAVE_SIMPLE_LATCHES
))
1710 force_single_succ_latches ();
1712 if (loops_state_satisfies_p (LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS
))
1713 mark_irreducible_loops ();
1716 record_loop_exits ();
1718 #ifdef ENABLE_CHECKING
1719 verify_loop_structure ();