1 /* Generic partial redundancy elimination with lazy code motion support.
2 Copyright (C) 1998, 1999, 2000, 2001 Free Software Foundation, Inc.
4 This file is part of GCC.
6 GCC is free software; you can redistribute it and/or modify it under
7 the terms of the GNU General Public License as published by the Free
8 Software Foundation; either version 2, or (at your option) any later
11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING. If not, write to the Free
18 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
21 /* These routines are meant to be used by various optimization
22 passes which can be modeled as lazy code motion problems.
23 Including, but not limited to:
25 * Traditional partial redundancy elimination.
27 * Placement of caller/caller register save/restores.
33 * Conversion of flat register files to a stacked register
36 * Dead load/store elimination.
38 These routines accept as input:
40 * Basic block information (number of blocks, lists of
41 predecessors and successors). Note the granularity
42 does not need to be basic block, they could be statements
45 * Bitmaps of local properties (computed, transparent and
46 anticipatable expressions).
48 The output of these routines is bitmap of redundant computations
49 and a bitmap of optimal placement points. */
56 #include "hard-reg-set.h"
59 #include "insn-config.h"
61 #include "basic-block.h"
64 /* We want target macros for the mode switching code to be able to refer
65 to instruction attribute values. */
66 #include "insn-attr.h"
68 /* Edge based LCM routines. */
69 static void compute_antinout_edge PARAMS ((sbitmap *, sbitmap *,
70 sbitmap *, sbitmap *));
71 static void compute_earliest PARAMS ((struct edge_list *, int,
75 static void compute_laterin PARAMS ((struct edge_list *, sbitmap *,
78 static void compute_insert_delete PARAMS ((struct edge_list *edge_list,
83 /* Edge based LCM routines on a reverse flowgraph. */
84 static void compute_farthest PARAMS ((struct edge_list *, int,
88 static void compute_nearerout PARAMS ((struct edge_list *, sbitmap *,
91 static void compute_rev_insert_delete PARAMS ((struct edge_list *edge_list,
96 /* Edge based lcm routines. */
98 /* Compute expression anticipatability at entrance and exit of each block.
99 This is done based on the flow graph, and not on the pred-succ lists.
100 Other than that, its pretty much identical to compute_antinout. */
103 compute_antinout_edge (antloc, transp, antin, antout)
111 basic_block *worklist, *qin, *qout, *qend;
114 /* Allocate a worklist array/queue. Entries are only added to the
115 list if they were not already on the list. So the size is
116 bounded by the number of basic blocks. */
117 qin = qout = worklist
118 = (basic_block *) xmalloc (sizeof (basic_block) * n_basic_blocks);
120 /* We want a maximal solution, so make an optimistic initialization of
122 sbitmap_vector_ones (antin, last_basic_block);
124 /* Put every block on the worklist; this is necessary because of the
125 optimistic initialization of ANTIN above. */
126 FOR_EACH_BB_REVERSE (bb)
133 qend = &worklist[n_basic_blocks];
134 qlen = n_basic_blocks;
136 /* Mark blocks which are predecessors of the exit block so that we
137 can easily identify them below. */
138 for (e = EXIT_BLOCK_PTR->pred; e; e = e->pred_next)
139 e->src->aux = EXIT_BLOCK_PTR;
141 /* Iterate until the worklist is empty. */
144 /* Take the first entry off the worklist. */
151 if (bb->aux == EXIT_BLOCK_PTR)
152 /* Do not clear the aux field for blocks which are predecessors of
153 the EXIT block. That way we never add then to the worklist
155 sbitmap_zero (antout[bb->index]);
158 /* Clear the aux field of this block so that it can be added to
159 the worklist again if necessary. */
161 sbitmap_intersection_of_succs (antout[bb->index], antin, bb->index);
164 if (sbitmap_a_or_b_and_c_cg (antin[bb->index], antloc[bb->index],
165 transp[bb->index], antout[bb->index]))
166 /* If the in state of this block changed, then we need
167 to add the predecessors of this block to the worklist
168 if they are not already on the worklist. */
169 for (e = bb->pred; e; e = e->pred_next)
170 if (!e->src->aux && e->src != ENTRY_BLOCK_PTR)
180 clear_aux_for_edges ();
181 clear_aux_for_blocks ();
185 /* Compute the earliest vector for edge based lcm. */
188 compute_earliest (edge_list, n_exprs, antin, antout, avout, kill, earliest)
189 struct edge_list *edge_list;
191 sbitmap *antin, *antout, *avout, *kill, *earliest;
193 sbitmap difference, temp_bitmap;
195 basic_block pred, succ;
197 num_edges = NUM_EDGES (edge_list);
199 difference = sbitmap_alloc (n_exprs);
200 temp_bitmap = sbitmap_alloc (n_exprs);
202 for (x = 0; x < num_edges; x++)
204 pred = INDEX_EDGE_PRED_BB (edge_list, x);
205 succ = INDEX_EDGE_SUCC_BB (edge_list, x);
206 if (pred == ENTRY_BLOCK_PTR)
207 sbitmap_copy (earliest[x], antin[succ->index]);
210 /* We refer to the EXIT_BLOCK index, instead of testing for
211 EXIT_BLOCK_PTR, so that EXIT_BLOCK_PTR's index can be
212 changed so as to pretend it's a regular block, so that
213 its antin can be taken into account. */
214 if (succ->index == EXIT_BLOCK)
215 sbitmap_zero (earliest[x]);
218 sbitmap_difference (difference, antin[succ->index],
220 sbitmap_not (temp_bitmap, antout[pred->index]);
221 sbitmap_a_and_b_or_c (earliest[x], difference,
222 kill[pred->index], temp_bitmap);
227 sbitmap_free (temp_bitmap);
228 sbitmap_free (difference);
231 /* later(p,s) is dependent on the calculation of laterin(p).
232 laterin(p) is dependent on the calculation of later(p2,p).
234 laterin(ENTRY) is defined as all 0's
235 later(ENTRY, succs(ENTRY)) are defined using laterin(ENTRY)
236 laterin(succs(ENTRY)) is defined by later(ENTRY, succs(ENTRY)).
238 If we progress in this manner, starting with all basic blocks
239 in the work list, anytime we change later(bb), we need to add
240 succs(bb) to the worklist if they are not already on the worklist.
244 We prime the worklist all the normal basic blocks. The ENTRY block can
245 never be added to the worklist since it is never the successor of any
246 block. We explicitly prevent the EXIT block from being added to the
249 We optimistically initialize LATER. That is the only time this routine
250 will compute LATER for an edge out of the entry block since the entry
251 block is never on the worklist. Thus, LATERIN is neither used nor
252 computed for the ENTRY block.
254 Since the EXIT block is never added to the worklist, we will neither
255 use nor compute LATERIN for the exit block. Edges which reach the
256 EXIT block are handled in the normal fashion inside the loop. However,
257 the insertion/deletion computation needs LATERIN(EXIT), so we have
261 compute_laterin (edge_list, earliest, antloc, later, laterin)
262 struct edge_list *edge_list;
263 sbitmap *earliest, *antloc, *later, *laterin;
267 basic_block *worklist, *qin, *qout, *qend, bb;
270 num_edges = NUM_EDGES (edge_list);
272 /* Allocate a worklist array/queue. Entries are only added to the
273 list if they were not already on the list. So the size is
274 bounded by the number of basic blocks. */
275 qin = qout = worklist
276 = (basic_block *) xmalloc (sizeof (basic_block) * (n_basic_blocks + 1));
278 /* Initialize a mapping from each edge to its index. */
279 for (i = 0; i < num_edges; i++)
280 INDEX_EDGE (edge_list, i)->aux = (void *) (size_t) i;
282 /* We want a maximal solution, so initially consider LATER true for
283 all edges. This allows propagation through a loop since the incoming
284 loop edge will have LATER set, so if all the other incoming edges
285 to the loop are set, then LATERIN will be set for the head of the
288 If the optimistic setting of LATER on that edge was incorrect (for
289 example the expression is ANTLOC in a block within the loop) then
290 this algorithm will detect it when we process the block at the head
291 of the optimistic edge. That will requeue the affected blocks. */
292 sbitmap_vector_ones (later, num_edges);
294 /* Note that even though we want an optimistic setting of LATER, we
295 do not want to be overly optimistic. Consider an outgoing edge from
296 the entry block. That edge should always have a LATER value the
297 same as EARLIEST for that edge. */
298 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
299 sbitmap_copy (later[(size_t) e->aux], earliest[(size_t) e->aux]);
301 /* Add all the blocks to the worklist. This prevents an early exit from
302 the loop given our optimistic initialization of LATER above. */
309 /* Note that we do not use the last allocated element for our queue,
310 as EXIT_BLOCK is never inserted into it. In fact the above allocation
311 of n_basic_blocks + 1 elements is not encessary. */
312 qend = &worklist[n_basic_blocks];
313 qlen = n_basic_blocks;
315 /* Iterate until the worklist is empty. */
318 /* Take the first entry off the worklist. */
325 /* Compute the intersection of LATERIN for each incoming edge to B. */
326 sbitmap_ones (laterin[bb->index]);
327 for (e = bb->pred; e != NULL; e = e->pred_next)
328 sbitmap_a_and_b (laterin[bb->index], laterin[bb->index], later[(size_t)e->aux]);
330 /* Calculate LATER for all outgoing edges. */
331 for (e = bb->succ; e != NULL; e = e->succ_next)
332 if (sbitmap_union_of_diff_cg (later[(size_t) e->aux],
333 earliest[(size_t) e->aux],
334 laterin[e->src->index],
335 antloc[e->src->index])
336 /* If LATER for an outgoing edge was changed, then we need
337 to add the target of the outgoing edge to the worklist. */
338 && e->dest != EXIT_BLOCK_PTR && e->dest->aux == 0)
348 /* Computation of insertion and deletion points requires computing LATERIN
349 for the EXIT block. We allocated an extra entry in the LATERIN array
350 for just this purpose. */
351 sbitmap_ones (laterin[last_basic_block]);
352 for (e = EXIT_BLOCK_PTR->pred; e != NULL; e = e->pred_next)
353 sbitmap_a_and_b (laterin[last_basic_block],
354 laterin[last_basic_block],
355 later[(size_t) e->aux]);
357 clear_aux_for_edges ();
361 /* Compute the insertion and deletion points for edge based LCM. */
364 compute_insert_delete (edge_list, antloc, later, laterin,
366 struct edge_list *edge_list;
367 sbitmap *antloc, *later, *laterin, *insert, *delete;
373 sbitmap_difference (delete[bb->index], antloc[bb->index], laterin[bb->index]);
375 for (x = 0; x < NUM_EDGES (edge_list); x++)
377 basic_block b = INDEX_EDGE_SUCC_BB (edge_list, x);
379 if (b == EXIT_BLOCK_PTR)
380 sbitmap_difference (insert[x], later[x], laterin[last_basic_block]);
382 sbitmap_difference (insert[x], later[x], laterin[b->index]);
386 /* Given local properties TRANSP, ANTLOC, AVOUT, KILL return the insert and
387 delete vectors for edge based LCM. Returns an edgelist which is used to
388 map the insert vector to what edge an expression should be inserted on. */
391 pre_edge_lcm (file, n_exprs, transp, avloc, antloc, kill, insert, delete)
392 FILE *file ATTRIBUTE_UNUSED;
401 sbitmap *antin, *antout, *earliest;
402 sbitmap *avin, *avout;
403 sbitmap *later, *laterin;
404 struct edge_list *edge_list;
407 edge_list = create_edge_list ();
408 num_edges = NUM_EDGES (edge_list);
410 #ifdef LCM_DEBUG_INFO
413 fprintf (file, "Edge List:\n");
414 verify_edge_list (file, edge_list);
415 print_edge_list (file, edge_list);
416 dump_sbitmap_vector (file, "transp", "", transp, last_basic_block);
417 dump_sbitmap_vector (file, "antloc", "", antloc, last_basic_block);
418 dump_sbitmap_vector (file, "avloc", "", avloc, last_basic_block);
419 dump_sbitmap_vector (file, "kill", "", kill, last_basic_block);
423 /* Compute global availability. */
424 avin = sbitmap_vector_alloc (last_basic_block, n_exprs);
425 avout = sbitmap_vector_alloc (last_basic_block, n_exprs);
426 compute_available (avloc, kill, avout, avin);
427 sbitmap_vector_free (avin);
429 /* Compute global anticipatability. */
430 antin = sbitmap_vector_alloc (last_basic_block, n_exprs);
431 antout = sbitmap_vector_alloc (last_basic_block, n_exprs);
432 compute_antinout_edge (antloc, transp, antin, antout);
434 #ifdef LCM_DEBUG_INFO
437 dump_sbitmap_vector (file, "antin", "", antin, last_basic_block);
438 dump_sbitmap_vector (file, "antout", "", antout, last_basic_block);
442 /* Compute earliestness. */
443 earliest = sbitmap_vector_alloc (num_edges, n_exprs);
444 compute_earliest (edge_list, n_exprs, antin, antout, avout, kill, earliest);
446 #ifdef LCM_DEBUG_INFO
448 dump_sbitmap_vector (file, "earliest", "", earliest, num_edges);
451 sbitmap_vector_free (antout);
452 sbitmap_vector_free (antin);
453 sbitmap_vector_free (avout);
455 later = sbitmap_vector_alloc (num_edges, n_exprs);
457 /* Allocate an extra element for the exit block in the laterin vector. */
458 laterin = sbitmap_vector_alloc (last_basic_block + 1, n_exprs);
459 compute_laterin (edge_list, earliest, antloc, later, laterin);
461 #ifdef LCM_DEBUG_INFO
464 dump_sbitmap_vector (file, "laterin", "", laterin, last_basic_block + 1);
465 dump_sbitmap_vector (file, "later", "", later, num_edges);
469 sbitmap_vector_free (earliest);
471 *insert = sbitmap_vector_alloc (num_edges, n_exprs);
472 *delete = sbitmap_vector_alloc (last_basic_block, n_exprs);
473 compute_insert_delete (edge_list, antloc, later, laterin, *insert, *delete);
475 sbitmap_vector_free (laterin);
476 sbitmap_vector_free (later);
478 #ifdef LCM_DEBUG_INFO
481 dump_sbitmap_vector (file, "pre_insert_map", "", *insert, num_edges);
482 dump_sbitmap_vector (file, "pre_delete_map", "", *delete,
490 /* Compute the AVIN and AVOUT vectors from the AVLOC and KILL vectors.
491 Return the number of passes we performed to iterate to a solution. */
494 compute_available (avloc, kill, avout, avin)
495 sbitmap *avloc, *kill, *avout, *avin;
498 basic_block *worklist, *qin, *qout, *qend, bb;
501 /* Allocate a worklist array/queue. Entries are only added to the
502 list if they were not already on the list. So the size is
503 bounded by the number of basic blocks. */
504 qin = qout = worklist
505 = (basic_block *) xmalloc (sizeof (basic_block) * n_basic_blocks);
507 /* We want a maximal solution. */
508 sbitmap_vector_ones (avout, last_basic_block);
510 /* Put every block on the worklist; this is necessary because of the
511 optimistic initialization of AVOUT above. */
519 qend = &worklist[n_basic_blocks];
520 qlen = n_basic_blocks;
522 /* Mark blocks which are successors of the entry block so that we
523 can easily identify them below. */
524 for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
525 e->dest->aux = ENTRY_BLOCK_PTR;
527 /* Iterate until the worklist is empty. */
530 /* Take the first entry off the worklist. */
537 /* If one of the predecessor blocks is the ENTRY block, then the
538 intersection of avouts is the null set. We can identify such blocks
539 by the special value in the AUX field in the block structure. */
540 if (bb->aux == ENTRY_BLOCK_PTR)
541 /* Do not clear the aux field for blocks which are successors of the
542 ENTRY block. That way we never add then to the worklist again. */
543 sbitmap_zero (avin[bb->index]);
546 /* Clear the aux field of this block so that it can be added to
547 the worklist again if necessary. */
549 sbitmap_intersection_of_preds (avin[bb->index], avout, bb->index);
552 if (sbitmap_union_of_diff_cg (avout[bb->index], avloc[bb->index], avin[bb->index], kill[bb->index]))
553 /* If the out state of this block changed, then we need
554 to add the successors of this block to the worklist
555 if they are not already on the worklist. */
556 for (e = bb->succ; e; e = e->succ_next)
557 if (!e->dest->aux && e->dest != EXIT_BLOCK_PTR)
568 clear_aux_for_edges ();
569 clear_aux_for_blocks ();
573 /* Compute the farthest vector for edge based lcm. */
576 compute_farthest (edge_list, n_exprs, st_avout, st_avin, st_antin,
578 struct edge_list *edge_list;
580 sbitmap *st_avout, *st_avin, *st_antin, *kill, *farthest;
582 sbitmap difference, temp_bitmap;
584 basic_block pred, succ;
586 num_edges = NUM_EDGES (edge_list);
588 difference = sbitmap_alloc (n_exprs);
589 temp_bitmap = sbitmap_alloc (n_exprs);
591 for (x = 0; x < num_edges; x++)
593 pred = INDEX_EDGE_PRED_BB (edge_list, x);
594 succ = INDEX_EDGE_SUCC_BB (edge_list, x);
595 if (succ == EXIT_BLOCK_PTR)
596 sbitmap_copy (farthest[x], st_avout[pred->index]);
599 if (pred == ENTRY_BLOCK_PTR)
600 sbitmap_zero (farthest[x]);
603 sbitmap_difference (difference, st_avout[pred->index],
604 st_antin[succ->index]);
605 sbitmap_not (temp_bitmap, st_avin[succ->index]);
606 sbitmap_a_and_b_or_c (farthest[x], difference,
607 kill[succ->index], temp_bitmap);
612 sbitmap_free (temp_bitmap);
613 sbitmap_free (difference);
616 /* Compute nearer and nearerout vectors for edge based lcm.
618 This is the mirror of compute_laterin, additional comments on the
619 implementation can be found before compute_laterin. */
622 compute_nearerout (edge_list, farthest, st_avloc, nearer, nearerout)
623 struct edge_list *edge_list;
624 sbitmap *farthest, *st_avloc, *nearer, *nearerout;
628 basic_block *worklist, *tos, bb;
630 num_edges = NUM_EDGES (edge_list);
632 /* Allocate a worklist array/queue. Entries are only added to the
633 list if they were not already on the list. So the size is
634 bounded by the number of basic blocks. */
636 = (basic_block *) xmalloc (sizeof (basic_block) * (n_basic_blocks + 1));
638 /* Initialize NEARER for each edge and build a mapping from an edge to
640 for (i = 0; i < num_edges; i++)
641 INDEX_EDGE (edge_list, i)->aux = (void *) (size_t) i;
643 /* We want a maximal solution. */
644 sbitmap_vector_ones (nearer, num_edges);
646 /* Note that even though we want an optimistic setting of NEARER, we
647 do not want to be overly optimistic. Consider an incoming edge to
648 the exit block. That edge should always have a NEARER value the
649 same as FARTHEST for that edge. */
650 for (e = EXIT_BLOCK_PTR->pred; e; e = e->pred_next)
651 sbitmap_copy (nearer[(size_t)e->aux], farthest[(size_t)e->aux]);
653 /* Add all the blocks to the worklist. This prevents an early exit
654 from the loop given our optimistic initialization of NEARER. */
661 /* Iterate until the worklist is empty. */
662 while (tos != worklist)
664 /* Take the first entry off the worklist. */
668 /* Compute the intersection of NEARER for each outgoing edge from B. */
669 sbitmap_ones (nearerout[bb->index]);
670 for (e = bb->succ; e != NULL; e = e->succ_next)
671 sbitmap_a_and_b (nearerout[bb->index], nearerout[bb->index],
672 nearer[(size_t) e->aux]);
674 /* Calculate NEARER for all incoming edges. */
675 for (e = bb->pred; e != NULL; e = e->pred_next)
676 if (sbitmap_union_of_diff_cg (nearer[(size_t) e->aux],
677 farthest[(size_t) e->aux],
678 nearerout[e->dest->index],
679 st_avloc[e->dest->index])
680 /* If NEARER for an incoming edge was changed, then we need
681 to add the source of the incoming edge to the worklist. */
682 && e->src != ENTRY_BLOCK_PTR && e->src->aux == 0)
689 /* Computation of insertion and deletion points requires computing NEAREROUT
690 for the ENTRY block. We allocated an extra entry in the NEAREROUT array
691 for just this purpose. */
692 sbitmap_ones (nearerout[last_basic_block]);
693 for (e = ENTRY_BLOCK_PTR->succ; e != NULL; e = e->succ_next)
694 sbitmap_a_and_b (nearerout[last_basic_block],
695 nearerout[last_basic_block],
696 nearer[(size_t) e->aux]);
698 clear_aux_for_edges ();
702 /* Compute the insertion and deletion points for edge based LCM. */
705 compute_rev_insert_delete (edge_list, st_avloc, nearer, nearerout,
707 struct edge_list *edge_list;
708 sbitmap *st_avloc, *nearer, *nearerout, *insert, *delete;
714 sbitmap_difference (delete[bb->index], st_avloc[bb->index], nearerout[bb->index]);
716 for (x = 0; x < NUM_EDGES (edge_list); x++)
718 basic_block b = INDEX_EDGE_PRED_BB (edge_list, x);
719 if (b == ENTRY_BLOCK_PTR)
720 sbitmap_difference (insert[x], nearer[x], nearerout[last_basic_block]);
722 sbitmap_difference (insert[x], nearer[x], nearerout[b->index]);
726 /* Given local properties TRANSP, ST_AVLOC, ST_ANTLOC, KILL return the
727 insert and delete vectors for edge based reverse LCM. Returns an
728 edgelist which is used to map the insert vector to what edge
729 an expression should be inserted on. */
732 pre_edge_rev_lcm (file, n_exprs, transp, st_avloc, st_antloc, kill,
734 FILE *file ATTRIBUTE_UNUSED;
743 sbitmap *st_antin, *st_antout;
744 sbitmap *st_avout, *st_avin, *farthest;
745 sbitmap *nearer, *nearerout;
746 struct edge_list *edge_list;
749 edge_list = create_edge_list ();
750 num_edges = NUM_EDGES (edge_list);
752 st_antin = (sbitmap *) sbitmap_vector_alloc (last_basic_block, n_exprs);
753 st_antout = (sbitmap *) sbitmap_vector_alloc (last_basic_block, n_exprs);
754 sbitmap_vector_zero (st_antin, last_basic_block);
755 sbitmap_vector_zero (st_antout, last_basic_block);
756 compute_antinout_edge (st_antloc, transp, st_antin, st_antout);
758 /* Compute global anticipatability. */
759 st_avout = sbitmap_vector_alloc (last_basic_block, n_exprs);
760 st_avin = sbitmap_vector_alloc (last_basic_block, n_exprs);
761 compute_available (st_avloc, kill, st_avout, st_avin);
763 #ifdef LCM_DEBUG_INFO
766 fprintf (file, "Edge List:\n");
767 verify_edge_list (file, edge_list);
768 print_edge_list (file, edge_list);
769 dump_sbitmap_vector (file, "transp", "", transp, last_basic_block);
770 dump_sbitmap_vector (file, "st_avloc", "", st_avloc, last_basic_block);
771 dump_sbitmap_vector (file, "st_antloc", "", st_antloc, last_basic_block);
772 dump_sbitmap_vector (file, "st_antin", "", st_antin, last_basic_block);
773 dump_sbitmap_vector (file, "st_antout", "", st_antout, last_basic_block);
774 dump_sbitmap_vector (file, "st_kill", "", kill, last_basic_block);
778 #ifdef LCM_DEBUG_INFO
781 dump_sbitmap_vector (file, "st_avout", "", st_avout, last_basic_block);
782 dump_sbitmap_vector (file, "st_avin", "", st_avin, last_basic_block);
786 /* Compute farthestness. */
787 farthest = sbitmap_vector_alloc (num_edges, n_exprs);
788 compute_farthest (edge_list, n_exprs, st_avout, st_avin, st_antin,
791 #ifdef LCM_DEBUG_INFO
793 dump_sbitmap_vector (file, "farthest", "", farthest, num_edges);
796 sbitmap_vector_free (st_antin);
797 sbitmap_vector_free (st_antout);
799 sbitmap_vector_free (st_avin);
800 sbitmap_vector_free (st_avout);
802 nearer = sbitmap_vector_alloc (num_edges, n_exprs);
804 /* Allocate an extra element for the entry block. */
805 nearerout = sbitmap_vector_alloc (last_basic_block + 1, n_exprs);
806 compute_nearerout (edge_list, farthest, st_avloc, nearer, nearerout);
808 #ifdef LCM_DEBUG_INFO
811 dump_sbitmap_vector (file, "nearerout", "", nearerout,
812 last_basic_block + 1);
813 dump_sbitmap_vector (file, "nearer", "", nearer, num_edges);
817 sbitmap_vector_free (farthest);
819 *insert = sbitmap_vector_alloc (num_edges, n_exprs);
820 *delete = sbitmap_vector_alloc (last_basic_block, n_exprs);
821 compute_rev_insert_delete (edge_list, st_avloc, nearer, nearerout,
824 sbitmap_vector_free (nearerout);
825 sbitmap_vector_free (nearer);
827 #ifdef LCM_DEBUG_INFO
830 dump_sbitmap_vector (file, "pre_insert_map", "", *insert, num_edges);
831 dump_sbitmap_vector (file, "pre_delete_map", "", *delete,
840 The algorithm for setting the modes consists of scanning the insn list
841 and finding all the insns which require a specific mode. Each insn gets
842 a unique struct seginfo element. These structures are inserted into a list
843 for each basic block. For each entity, there is an array of bb_info over
844 the flow graph basic blocks (local var 'bb_info'), and contains a list
845 of all insns within that basic block, in the order they are encountered.
847 For each entity, any basic block WITHOUT any insns requiring a specific
848 mode are given a single entry, without a mode. (Each basic block
849 in the flow graph must have at least one entry in the segment table.)
851 The LCM algorithm is then run over the flow graph to determine where to
852 place the sets to the highest-priority value in respect of first the first
853 insn in any one block. Any adjustments required to the transparancy
854 vectors are made, then the next iteration starts for the next-lower
855 priority mode, till for each entity all modes are exhasted.
857 More details are located in the code for optimize_mode_switching(). */
859 /* This structure contains the information for each insn which requires
860 either single or double mode to be set.
861 MODE is the mode this insn must be executed in.
862 INSN_PTR is the insn to be executed (may be the note that marks the
863 beginning of a basic block).
864 BBNUM is the flow graph basic block this insn occurs in.
865 NEXT is the next insn in the same basic block. */
871 struct seginfo *next;
872 HARD_REG_SET regs_live;
877 struct seginfo *seginfo;
881 /* These bitmaps are used for the LCM algorithm. */
883 #ifdef OPTIMIZE_MODE_SWITCHING
884 static sbitmap *antic;
885 static sbitmap *transp;
886 static sbitmap *comp;
887 static sbitmap *delete;
888 static sbitmap *insert;
890 static struct seginfo * new_seginfo PARAMS ((int, rtx, int, HARD_REG_SET));
891 static void add_seginfo PARAMS ((struct bb_info *, struct seginfo *));
892 static void reg_dies PARAMS ((rtx, HARD_REG_SET));
893 static void reg_becomes_live PARAMS ((rtx, rtx, void *));
894 static void make_preds_opaque PARAMS ((basic_block, int));
897 #ifdef OPTIMIZE_MODE_SWITCHING
899 /* This function will allocate a new BBINFO structure, initialized
900 with the MODE, INSN, and basic block BB parameters. */
902 static struct seginfo *
903 new_seginfo (mode, insn, bb, regs_live)
907 HARD_REG_SET regs_live;
910 ptr = xmalloc (sizeof (struct seginfo));
912 ptr->insn_ptr = insn;
915 COPY_HARD_REG_SET (ptr->regs_live, regs_live);
919 /* Add a seginfo element to the end of a list.
920 HEAD is a pointer to the list beginning.
921 INFO is the structure to be linked in. */
924 add_seginfo (head, info)
925 struct bb_info *head;
926 struct seginfo *info;
930 if (head->seginfo == NULL)
931 head->seginfo = info;
935 while (ptr->next != NULL)
941 /* Make all predecessors of basic block B opaque, recursively, till we hit
942 some that are already non-transparent, or an edge where aux is set; that
943 denotes that a mode set is to be done on that edge.
944 J is the bit number in the bitmaps that corresponds to the entity that
945 we are currently handling mode-switching for. */
948 make_preds_opaque (b, j)
954 for (e = b->pred; e; e = e->pred_next)
956 basic_block pb = e->src;
958 if (e->aux || ! TEST_BIT (transp[pb->index], j))
961 RESET_BIT (transp[pb->index], j);
962 make_preds_opaque (pb, j);
966 /* Record in LIVE that register REG died. */
975 if (GET_CODE (reg) != REG)
979 if (regno < FIRST_PSEUDO_REGISTER)
980 for (nregs = HARD_REGNO_NREGS (regno, GET_MODE (reg)) - 1; nregs >= 0;
982 CLEAR_HARD_REG_BIT (live, regno + nregs);
985 /* Record in LIVE that register REG became live.
986 This is called via note_stores. */
989 reg_becomes_live (reg, setter, live)
991 rtx setter ATTRIBUTE_UNUSED;
996 if (GET_CODE (reg) == SUBREG)
997 reg = SUBREG_REG (reg);
999 if (GET_CODE (reg) != REG)
1002 regno = REGNO (reg);
1003 if (regno < FIRST_PSEUDO_REGISTER)
1004 for (nregs = HARD_REGNO_NREGS (regno, GET_MODE (reg)) - 1; nregs >= 0;
1006 SET_HARD_REG_BIT (* (HARD_REG_SET *) live, regno + nregs);
1009 /* Find all insns that need a particular mode setting, and insert the
1010 necessary mode switches. Return true if we did work. */
1013 optimize_mode_switching (file)
1019 int need_commit = 0;
1021 struct edge_list *edge_list;
1022 static const int num_modes[] = NUM_MODES_FOR_MODE_SWITCHING;
1023 #define N_ENTITIES ARRAY_SIZE (num_modes)
1024 int entity_map[N_ENTITIES];
1025 struct bb_info *bb_info[N_ENTITIES];
1028 int max_num_modes = 0;
1029 bool emited = false;
1033 /* Increment last_basic_block before allocating bb_info. */
1037 for (e = N_ENTITIES - 1, n_entities = 0; e >= 0; e--)
1038 if (OPTIMIZE_MODE_SWITCHING (e))
1040 /* Create the list of segments within each basic block. */
1042 = (struct bb_info *) xcalloc (last_basic_block, sizeof **bb_info);
1043 entity_map[n_entities++] = e;
1044 if (num_modes[e] > max_num_modes)
1045 max_num_modes = num_modes[e];
1049 /* Decrement it back in case we return below. */
1057 /* We're going to pretend the EXIT_BLOCK is a regular basic block,
1058 so that switching back to normal mode when entering the
1059 EXIT_BLOCK isn't optimized away. We do this by incrementing the
1060 basic block count, growing the VARRAY of basic_block_info and
1061 appending the EXIT_BLOCK_PTR to it. */
1063 if (VARRAY_SIZE (basic_block_info) < last_basic_block)
1064 VARRAY_GROW (basic_block_info, last_basic_block);
1065 BASIC_BLOCK (last_basic_block - 1) = EXIT_BLOCK_PTR;
1066 EXIT_BLOCK_PTR->index = last_basic_block - 1;
1069 /* Create the bitmap vectors. */
1071 antic = sbitmap_vector_alloc (last_basic_block, n_entities);
1072 transp = sbitmap_vector_alloc (last_basic_block, n_entities);
1073 comp = sbitmap_vector_alloc (last_basic_block, n_entities);
1075 sbitmap_vector_ones (transp, last_basic_block);
1077 for (j = n_entities - 1; j >= 0; j--)
1079 int e = entity_map[j];
1080 int no_mode = num_modes[e];
1081 struct bb_info *info = bb_info[j];
1083 /* Determine what the first use (if any) need for a mode of entity E is.
1084 This will be the mode that is anticipatable for this block.
1085 Also compute the initial transparency settings. */
1088 struct seginfo *ptr;
1089 int last_mode = no_mode;
1090 HARD_REG_SET live_now;
1092 REG_SET_TO_HARD_REG_SET (live_now,
1093 bb->global_live_at_start);
1094 for (insn = bb->head;
1095 insn != NULL && insn != NEXT_INSN (bb->end);
1096 insn = NEXT_INSN (insn))
1100 int mode = MODE_NEEDED (e, insn);
1103 if (mode != no_mode && mode != last_mode)
1106 ptr = new_seginfo (mode, insn, bb->index, live_now);
1107 add_seginfo (info + bb->index, ptr);
1108 RESET_BIT (transp[bb->index], j);
1111 /* Update LIVE_NOW. */
1112 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
1113 if (REG_NOTE_KIND (link) == REG_DEAD)
1114 reg_dies (XEXP (link, 0), live_now);
1116 note_stores (PATTERN (insn), reg_becomes_live, &live_now);
1117 for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
1118 if (REG_NOTE_KIND (link) == REG_UNUSED)
1119 reg_dies (XEXP (link, 0), live_now);
1123 info[bb->index].computing = last_mode;
1124 /* Check for blocks without ANY mode requirements. */
1125 if (last_mode == no_mode)
1127 ptr = new_seginfo (no_mode, insn, bb->index, live_now);
1128 add_seginfo (info + bb->index, ptr);
1133 int mode = NORMAL_MODE (e);
1135 if (mode != no_mode)
1139 for (eg = ENTRY_BLOCK_PTR->succ; eg; eg = eg->succ_next)
1143 /* By always making this nontransparent, we save
1144 an extra check in make_preds_opaque. We also
1145 need this to avoid confusing pre_edge_lcm when
1146 antic is cleared but transp and comp are set. */
1147 RESET_BIT (transp[bb->index], j);
1149 /* If the block already has MODE, pretend it
1150 has none (because we don't need to set it),
1151 but retain whatever mode it computes. */
1152 if (info[bb->index].seginfo->mode == mode)
1153 info[bb->index].seginfo->mode = no_mode;
1155 /* Insert a fake computing definition of MODE into entry
1156 blocks which compute no mode. This represents the mode on
1158 else if (info[bb->index].computing == no_mode)
1160 info[bb->index].computing = mode;
1161 info[bb->index].seginfo->mode = no_mode;
1165 bb = EXIT_BLOCK_PTR;
1166 info[bb->index].seginfo->mode = mode;
1169 #endif /* NORMAL_MODE */
1172 kill = sbitmap_vector_alloc (last_basic_block, n_entities);
1173 for (i = 0; i < max_num_modes; i++)
1175 int current_mode[N_ENTITIES];
1177 /* Set the anticipatable and computing arrays. */
1178 sbitmap_vector_zero (antic, last_basic_block);
1179 sbitmap_vector_zero (comp, last_basic_block);
1180 for (j = n_entities - 1; j >= 0; j--)
1182 int m = current_mode[j] = MODE_PRIORITY_TO_MODE (entity_map[j], i);
1183 struct bb_info *info = bb_info[j];
1187 if (info[bb->index].seginfo->mode == m)
1188 SET_BIT (antic[bb->index], j);
1190 if (info[bb->index].computing == m)
1191 SET_BIT (comp[bb->index], j);
1195 /* Calculate the optimal locations for the
1196 placement mode switches to modes with priority I. */
1199 sbitmap_not (kill[bb->index], transp[bb->index]);
1200 edge_list = pre_edge_lcm (file, 1, transp, comp, antic,
1201 kill, &insert, &delete);
1203 for (j = n_entities - 1; j >= 0; j--)
1205 /* Insert all mode sets that have been inserted by lcm. */
1206 int no_mode = num_modes[entity_map[j]];
1208 /* Wherever we have moved a mode setting upwards in the flow graph,
1209 the blocks between the new setting site and the now redundant
1210 computation ceases to be transparent for any lower-priority
1211 mode of the same entity. First set the aux field of each
1212 insertion site edge non-transparent, then propagate the new
1213 non-transparency from the redundant computation upwards till
1214 we hit an insertion site or an already non-transparent block. */
1215 for (e = NUM_EDGES (edge_list) - 1; e >= 0; e--)
1217 edge eg = INDEX_EDGE (edge_list, e);
1220 HARD_REG_SET live_at_edge;
1225 if (! TEST_BIT (insert[e], j))
1228 eg->aux = (void *)1;
1230 mode = current_mode[j];
1233 REG_SET_TO_HARD_REG_SET (live_at_edge,
1234 src_bb->global_live_at_end);
1237 EMIT_MODE_SET (entity_map[j], mode, live_at_edge);
1238 mode_set = gen_sequence ();
1241 /* Do not bother to insert empty sequence. */
1242 if (GET_CODE (mode_set) == SEQUENCE
1243 && !XVECLEN (mode_set, 0))
1246 /* If this is an abnormal edge, we'll insert at the end
1247 of the previous block. */
1248 if (eg->flags & EDGE_ABNORMAL)
1251 if (GET_CODE (src_bb->end) == JUMP_INSN)
1252 emit_insn_before (mode_set, src_bb->end);
1253 /* It doesn't make sense to switch to normal mode
1254 after a CALL_INSN, so we're going to abort if we
1255 find one. The cases in which a CALL_INSN may
1256 have an abnormal edge are sibcalls and EH edges.
1257 In the case of sibcalls, the dest basic-block is
1258 the EXIT_BLOCK, that runs in normal mode; it is
1259 assumed that a sibcall insn requires normal mode
1260 itself, so no mode switch would be required after
1261 the call (it wouldn't make sense, anyway). In
1262 the case of EH edges, EH entry points also start
1263 in normal mode, so a similar reasoning applies. */
1264 else if (GET_CODE (src_bb->end) == INSN)
1265 emit_insn_after (mode_set, src_bb->end);
1268 bb_info[j][src_bb->index].computing = mode;
1269 RESET_BIT (transp[src_bb->index], j);
1274 insert_insn_on_edge (mode_set, eg);
1278 FOR_EACH_BB_REVERSE (bb)
1279 if (TEST_BIT (delete[bb->index], j))
1281 make_preds_opaque (bb, j);
1282 /* Cancel the 'deleted' mode set. */
1283 bb_info[j][bb->index].seginfo->mode = no_mode;
1287 clear_aux_for_edges ();
1288 free_edge_list (edge_list);
1292 /* Restore the special status of EXIT_BLOCK. */
1294 VARRAY_POP (basic_block_info);
1295 EXIT_BLOCK_PTR->index = EXIT_BLOCK;
1298 /* Now output the remaining mode sets in all the segments. */
1299 for (j = n_entities - 1; j >= 0; j--)
1301 int no_mode = num_modes[entity_map[j]];
1304 if (bb_info[j][last_basic_block].seginfo->mode != no_mode)
1307 struct seginfo *ptr = bb_info[j][last_basic_block].seginfo;
1309 for (eg = EXIT_BLOCK_PTR->pred; eg; eg = eg->pred_next)
1313 if (bb_info[j][eg->src->index].computing == ptr->mode)
1317 EMIT_MODE_SET (entity_map[j], ptr->mode, ptr->regs_live);
1318 mode_set = gen_sequence ();
1321 /* Do not bother to insert empty sequence. */
1322 if (GET_CODE (mode_set) == SEQUENCE
1323 && !XVECLEN (mode_set, 0))
1326 /* If this is an abnormal edge, we'll insert at the end of the
1328 if (eg->flags & EDGE_ABNORMAL)
1331 if (GET_CODE (eg->src->end) == JUMP_INSN)
1332 emit_insn_before (mode_set, eg->src->end);
1333 else if (GET_CODE (eg->src->end) == INSN)
1334 emit_insn_after (mode_set, eg->src->end);
1341 insert_insn_on_edge (mode_set, eg);
1348 FOR_EACH_BB_REVERSE (bb)
1350 struct seginfo *ptr, *next;
1351 for (ptr = bb_info[j][bb->index].seginfo; ptr; ptr = next)
1354 if (ptr->mode != no_mode)
1359 EMIT_MODE_SET (entity_map[j], ptr->mode, ptr->regs_live);
1360 mode_set = gen_sequence ();
1363 /* Do not bother to insert empty sequence. */
1364 if (GET_CODE (mode_set) == SEQUENCE
1365 && !XVECLEN (mode_set, 0))
1369 if (GET_CODE (ptr->insn_ptr) == NOTE
1370 && (NOTE_LINE_NUMBER (ptr->insn_ptr)
1371 == NOTE_INSN_BASIC_BLOCK))
1372 emit_insn_after (mode_set, ptr->insn_ptr);
1374 emit_insn_before (mode_set, ptr->insn_ptr);
1384 /* Finished. Free up all the things we've allocated. */
1386 sbitmap_vector_free (kill);
1387 sbitmap_vector_free (antic);
1388 sbitmap_vector_free (transp);
1389 sbitmap_vector_free (comp);
1390 sbitmap_vector_free (delete);
1391 sbitmap_vector_free (insert);
1394 commit_edge_insertions ();
1396 if (!need_commit && !emited)
1399 max_regno = max_reg_num ();
1400 allocate_reg_info (max_regno, FALSE, FALSE);
1401 update_life_info_in_dirty_blocks (UPDATE_LIFE_GLOBAL_RM_NOTES,
1402 (PROP_DEATH_NOTES | PROP_KILL_DEAD_CODE
1403 | PROP_SCAN_DEAD_CODE));
1407 #endif /* OPTIMIZE_MODE_SWITCHING */