summaryrefslogtreecommitdiffstats
path: root/gcc/lcm.c
blob: 43bebe74ece03695a8cc956130acad4164952f3b (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
/* Generic partial redundancy elimination with lazy code motion support.
   Copyright (C) 1998, 1999, 2000, 2001 Free Software Foundation, Inc.

This file is part of GNU CC.

GNU CC is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.

GNU CC is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with GNU CC; see the file COPYING.  If not, write to
the Free Software Foundation, 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.  */

/* These routines are meant to be used by various optimization
   passes which can be modeled as lazy code motion problems. 
   Including, but not limited to:

	* Traditional partial redundancy elimination.

	* Placement of caller/caller register save/restores.

	* Load/store motion.

	* Copy motion.

	* Conversion of flat register files to a stacked register
	model.

	* Dead load/store elimination.

  These routines accept as input:

	* Basic block information (number of blocks, lists of
	predecessors and successors).  Note the granularity
	does not need to be basic block, they could be statements
	or functions.

	* Bitmaps of local properties (computed, transparent and
	anticipatable expressions).

  The output of these routines is bitmap of redundant computations
  and a bitmap of optimal placement points.  */


#include "config.h"
#include "system.h"
#include "rtl.h"
#include "regs.h"
#include "hard-reg-set.h"
#include "flags.h"
#include "real.h"
#include "insn-config.h"
#include "recog.h"
#include "basic-block.h"
#include "tm_p.h"

/* We want target macros for the mode switching code to be able to refer
   to instruction attribute values.  */
#include "insn-attr.h"

/* Edge based LCM routines.  */
static void compute_antinout_edge	PARAMS ((sbitmap *, sbitmap *,
						 sbitmap *, sbitmap *));
static void compute_earliest		PARAMS ((struct edge_list *, int,
						 sbitmap *, sbitmap *,
						 sbitmap *, sbitmap *,
						 sbitmap *));
static void compute_laterin		PARAMS ((struct edge_list *, sbitmap *,
						 sbitmap *, sbitmap *,
						 sbitmap *));
static void compute_insert_delete	PARAMS ((struct edge_list *edge_list,
						 sbitmap *, sbitmap *,
						 sbitmap *, sbitmap *,
						 sbitmap *));

/* Edge based LCM routines on a reverse flowgraph.  */
static void compute_farthest		PARAMS ((struct edge_list *, int,
						 sbitmap *, sbitmap *,
						 sbitmap*, sbitmap *,
						 sbitmap *));
static void compute_nearerout		PARAMS ((struct edge_list *, sbitmap *,
						 sbitmap *, sbitmap *,
						 sbitmap *));
static void compute_rev_insert_delete	PARAMS ((struct edge_list *edge_list,
						 sbitmap *, sbitmap *,
						 sbitmap *, sbitmap *,
						 sbitmap *));

/* Edge based lcm routines.  */

/* Compute expression anticipatability at entrance and exit of each block. 
   This is done based on the flow graph, and not on the pred-succ lists.  
   Other than that, its pretty much identical to compute_antinout.  */

static void
compute_antinout_edge (antloc, transp, antin, antout)
     sbitmap *antloc;
     sbitmap *transp;
     sbitmap *antin;
     sbitmap *antout;
{
  int bb;
  edge e;
  basic_block *worklist, *qin, *qout, *qend;
  unsigned int qlen;

  /* Allocate a worklist array/queue.  Entries are only added to the
     list if they were not already on the list.  So the size is
     bounded by the number of basic blocks.  */
  qin = qout = worklist
    = (basic_block *) xmalloc (sizeof (basic_block) * n_basic_blocks);

  /* We want a maximal solution, so make an optimistic initialization of
     ANTIN.  */
  sbitmap_vector_ones (antin, n_basic_blocks);

  /* Put every block on the worklist; this is necessary because of the
     optimistic initialization of ANTIN above.  */
  for (bb = n_basic_blocks - 1; bb >= 0; bb--)
    {
      *qin++ = BASIC_BLOCK (bb);
      BASIC_BLOCK (bb)->aux = BASIC_BLOCK (bb);
    }
  
  qin = worklist;
  qend = &worklist[n_basic_blocks];
  qlen = n_basic_blocks;

  /* Mark blocks which are predecessors of the exit block so that we
     can easily identify them below.  */
  for (e = EXIT_BLOCK_PTR->pred; e; e = e->pred_next)
    e->src->aux = EXIT_BLOCK_PTR;

  /* Iterate until the worklist is empty.  */
  while (qlen)
    {
      /* Take the first entry off the worklist.  */
      basic_block b = *qout++;
      bb = b->index;
      qlen--;

      if (qout >= qend)
        qout = worklist;

      if (b->aux == EXIT_BLOCK_PTR)
	/* Do not clear the aux field for blocks which are predecessors of
	   the EXIT block.  That way we never add then to the worklist
	   again.  */
	sbitmap_zero (antout[bb]);
      else
	{
	  /* Clear the aux field of this block so that it can be added to
	     the worklist again if necessary.  */
	  b->aux = NULL;
	  sbitmap_intersection_of_succs (antout[bb], antin, bb);
	}

      if (sbitmap_a_or_b_and_c (antin[bb], antloc[bb], transp[bb], antout[bb]))
	/* If the in state of this block changed, then we need
	   to add the predecessors of this block to the worklist
	   if they are not already on the worklist.  */
	for (e = b->pred; e; e = e->pred_next)
	  if (!e->src->aux && e->src != ENTRY_BLOCK_PTR)
	    {
	      *qin++ = e->src;
	      e->src->aux = e;
	      qlen++;
	      if (qin >= qend)
	        qin = worklist;
	    }
    }

  free (worklist);
}

/* Compute the earliest vector for edge based lcm.  */

static void
compute_earliest (edge_list, n_exprs, antin, antout, avout, kill, earliest)
     struct edge_list *edge_list;
     int n_exprs;
     sbitmap *antin, *antout, *avout, *kill, *earliest;
{
  sbitmap difference, temp_bitmap;
  int x, num_edges; 
  basic_block pred, succ;

  num_edges = NUM_EDGES (edge_list);

  difference = sbitmap_alloc (n_exprs);
  temp_bitmap = sbitmap_alloc (n_exprs);

  for (x = 0; x < num_edges; x++)
    {
      pred = INDEX_EDGE_PRED_BB (edge_list, x);
      succ = INDEX_EDGE_SUCC_BB (edge_list, x);
      if (pred == ENTRY_BLOCK_PTR)
	sbitmap_copy (earliest[x], antin[succ->index]);
      else
        {
	  /* We refer to the EXIT_BLOCK index, instead of testing for
	     EXIT_BLOCK_PTR, so that EXIT_BLOCK_PTR's index can be
	     changed so as to pretend it's a regular block, so that
	     its antin can be taken into account.  */
	  if (succ->index == EXIT_BLOCK)
	    sbitmap_zero (earliest[x]);
	  else
	    {
	      sbitmap_difference (difference, antin[succ->index], 
	      			  avout[pred->index]);
	      sbitmap_not (temp_bitmap, antout[pred->index]);
	      sbitmap_a_and_b_or_c (earliest[x], difference,
				    kill[pred->index], temp_bitmap);
	    }
	}
    }

  free (temp_bitmap);
  free (difference);
}

/* later(p,s) is dependent on the calculation of laterin(p).
   laterin(p) is dependent on the calculation of later(p2,p).

     laterin(ENTRY) is defined as all 0's
     later(ENTRY, succs(ENTRY)) are defined using laterin(ENTRY)
     laterin(succs(ENTRY)) is defined by later(ENTRY, succs(ENTRY)).

   If we progress in this manner, starting with all basic blocks
   in the work list, anytime we change later(bb), we need to add
   succs(bb) to the worklist if they are not already on the worklist.

   Boundary conditions:

     We prime the worklist all the normal basic blocks.   The ENTRY block can
     never be added to the worklist since it is never the successor of any
     block.  We explicitly prevent the EXIT block from being added to the
     worklist.

     We optimistically initialize LATER.  That is the only time this routine
     will compute LATER for an edge out of the entry block since the entry
     block is never on the worklist.  Thus, LATERIN is neither used nor
     computed for the ENTRY block.

     Since the EXIT block is never added to the worklist, we will neither
     use nor compute LATERIN for the exit block.  Edges which reach the
     EXIT block are handled in the normal fashion inside the loop.  However,
     the insertion/deletion computation needs LATERIN(EXIT), so we have
     to compute it.  */
 
static void
compute_laterin (edge_list, earliest, antloc, later, laterin)
     struct edge_list *edge_list;
     sbitmap *earliest, *antloc, *later, *laterin;
{
  int bb, num_edges, i;
  edge e;
  basic_block *worklist, *qin, *qout, *qend;
  unsigned int qlen;

  num_edges = NUM_EDGES (edge_list);

  /* Allocate a worklist array/queue.  Entries are only added to the
     list if they were not already on the list.  So the size is
     bounded by the number of basic blocks.  */
  qin = qout = worklist
    = (basic_block *) xmalloc (sizeof (basic_block) * (n_basic_blocks + 1));

  /* Initialize a mapping from each edge to its index.  */
  for (i = 0; i < num_edges; i++)
    INDEX_EDGE (edge_list, i)->aux = (void *) (size_t) i;

  /* We want a maximal solution, so initially consider LATER true for
     all edges.  This allows propagation through a loop since the incoming
     loop edge will have LATER set, so if all the other incoming edges
     to the loop are set, then LATERIN will be set for the head of the
     loop.

     If the optimistic setting of LATER on that edge was incorrect (for
     example the expression is ANTLOC in a block within the loop) then
     this algorithm will detect it when we process the block at the head
     of the optimistic edge.  That will requeue the affected blocks.  */
  sbitmap_vector_ones (later, num_edges);

  /* Note that even though we want an optimistic setting of LATER, we
     do not want to be overly optimistic.  Consider an outgoing edge from
     the entry block.  That edge should always have a LATER value the
     same as EARLIEST for that edge.  */
  for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
    sbitmap_copy (later[(size_t) e->aux], earliest[(size_t) e->aux]);

  /* Add all the blocks to the worklist.  This prevents an early exit from
     the loop given our optimistic initialization of LATER above.  */
  for (bb = 0; bb < n_basic_blocks; bb++)
    {
      basic_block b = BASIC_BLOCK (bb);
      *qin++ = b;
      b->aux = b;
    }
  qin = worklist;
  /* Note that we do not use the last allocated element for our queue,
     as EXIT_BLOCK is never inserted into it. In fact the above allocation
     of n_basic_blocks + 1 elements is not encessary. */
  qend = &worklist[n_basic_blocks];
  qlen = n_basic_blocks;

  /* Iterate until the worklist is empty.  */
  while (qlen)
    {
      /* Take the first entry off the worklist.  */
      basic_block b = *qout++;
      b->aux = NULL;
      qlen--;
      if (qout >= qend)
        qout = worklist;

      /* Compute the intersection of LATERIN for each incoming edge to B.  */
      bb = b->index;
      sbitmap_ones (laterin[bb]);
      for (e = b->pred; e != NULL; e = e->pred_next)
	sbitmap_a_and_b (laterin[bb], laterin[bb], later[(size_t)e->aux]);

      /* Calculate LATER for all outgoing edges.  */
      for (e = b->succ; e != NULL; e = e->succ_next)
	if (sbitmap_union_of_diff (later[(size_t) e->aux],
				   earliest[(size_t) e->aux],
				   laterin[e->src->index],
				   antloc[e->src->index])
	    /* If LATER for an outgoing edge was changed, then we need
	       to add the target of the outgoing edge to the worklist.  */
	    && e->dest != EXIT_BLOCK_PTR && e->dest->aux == 0)
	  {
	    *qin++ = e->dest;
	    e->dest->aux = e;
	    qlen++;
	    if (qin >= qend)
	      qin = worklist;
	  }
    }

  /* Computation of insertion and deletion points requires computing LATERIN
     for the EXIT block.  We allocated an extra entry in the LATERIN array
     for just this purpose.  */
  sbitmap_ones (laterin[n_basic_blocks]);
  for (e = EXIT_BLOCK_PTR->pred; e != NULL; e = e->pred_next)
    sbitmap_a_and_b (laterin[n_basic_blocks],
		     laterin[n_basic_blocks],
		     later[(size_t) e->aux]);

  free (worklist);
}

/* Compute the insertion and deletion points for edge based LCM.  */

static void
compute_insert_delete (edge_list, antloc, later, laterin,
		       insert, delete)
     struct edge_list *edge_list;
     sbitmap *antloc, *later, *laterin, *insert, *delete;
{
  int x;

  for (x = 0; x < n_basic_blocks; x++)
    sbitmap_difference (delete[x], antloc[x], laterin[x]);
     
  for (x = 0; x < NUM_EDGES (edge_list); x++)
    {
      basic_block b = INDEX_EDGE_SUCC_BB (edge_list, x);

      if (b == EXIT_BLOCK_PTR)
	sbitmap_difference (insert[x], later[x], laterin[n_basic_blocks]);
      else
	sbitmap_difference (insert[x], later[x], laterin[b->index]);
    }
}

/* Given local properties TRANSP, ANTLOC, AVOUT, KILL return the insert and
   delete vectors for edge based LCM.  Returns an edgelist which is used to
   map the insert vector to what edge an expression should be inserted on.  */

struct edge_list *
pre_edge_lcm (file, n_exprs, transp, avloc, antloc, kill, insert, delete)
     FILE *file ATTRIBUTE_UNUSED;
     int n_exprs;
     sbitmap *transp;
     sbitmap *avloc;
     sbitmap *antloc;
     sbitmap *kill;
     sbitmap **insert;
     sbitmap **delete;
{
  sbitmap *antin, *antout, *earliest;
  sbitmap *avin, *avout;
  sbitmap *later, *laterin;
  struct edge_list *edge_list;
  int num_edges;

  edge_list = create_edge_list ();
  num_edges = NUM_EDGES (edge_list);

#ifdef LCM_DEBUG_INFO
  if (file)
    {
      fprintf (file, "Edge List:\n");
      verify_edge_list (file, edge_list);
      print_edge_list (file, edge_list);
      dump_sbitmap_vector (file, "transp", "", transp, n_basic_blocks);
      dump_sbitmap_vector (file, "antloc", "", antloc, n_basic_blocks);
      dump_sbitmap_vector (file, "avloc", "", avloc, n_basic_blocks);
      dump_sbitmap_vector (file, "kill", "", kill, n_basic_blocks);
    }
#endif

  /* Compute global availability.  */
  avin = sbitmap_vector_alloc (n_basic_blocks, n_exprs);
  avout = sbitmap_vector_alloc (n_basic_blocks, n_exprs);
  compute_available (avloc, kill, avout, avin);
  free (avin);

  /* Compute global anticipatability.  */
  antin = sbitmap_vector_alloc (n_basic_blocks, n_exprs);
  antout = sbitmap_vector_alloc (n_basic_blocks, n_exprs);
  compute_antinout_edge (antloc, transp, antin, antout);

#ifdef LCM_DEBUG_INFO
  if (file)
    {
      dump_sbitmap_vector (file, "antin", "", antin, n_basic_blocks);
      dump_sbitmap_vector (file, "antout", "", antout, n_basic_blocks);
    }
#endif

  /* Compute earliestness.  */
  earliest = sbitmap_vector_alloc (num_edges, n_exprs);
  compute_earliest (edge_list, n_exprs, antin, antout, avout, kill, earliest);

#ifdef LCM_DEBUG_INFO
  if (file)
    dump_sbitmap_vector (file, "earliest", "", earliest, num_edges);
#endif

  free (antout);
  free (antin);
  free (avout);

  later = sbitmap_vector_alloc (num_edges, n_exprs);

  /* Allocate an extra element for the exit block in the laterin vector.  */
  laterin = sbitmap_vector_alloc (n_basic_blocks + 1, n_exprs);
  compute_laterin (edge_list, earliest, antloc, later, laterin);

#ifdef LCM_DEBUG_INFO
  if (file)
    {
      dump_sbitmap_vector (file, "laterin", "", laterin, n_basic_blocks + 1);
      dump_sbitmap_vector (file, "later", "", later, num_edges);
    }
#endif

  free (earliest);

  *insert = sbitmap_vector_alloc (num_edges, n_exprs);
  *delete = sbitmap_vector_alloc (n_basic_blocks, n_exprs);
  compute_insert_delete (edge_list, antloc, later, laterin, *insert, *delete);

  free (laterin);
  free (later);

#ifdef LCM_DEBUG_INFO
  if (file)
    {
      dump_sbitmap_vector (file, "pre_insert_map", "", *insert, num_edges);
      dump_sbitmap_vector (file, "pre_delete_map", "", *delete,
			   n_basic_blocks);
    }
#endif

  return edge_list;
}

/* Compute the AVIN and AVOUT vectors from the AVLOC and KILL vectors.
   Return the number of passes we performed to iterate to a solution.  */

void
compute_available (avloc, kill, avout, avin)
     sbitmap *avloc, *kill, *avout, *avin;  
{
  int bb;
  edge e;
  basic_block *worklist, *qin, *qout, *qend;
  unsigned int qlen;

  /* Allocate a worklist array/queue.  Entries are only added to the
     list if they were not already on the list.  So the size is
     bounded by the number of basic blocks.  */
  qin = qout = worklist
    = (basic_block *) xmalloc (sizeof (basic_block) * n_basic_blocks);

  /* We want a maximal solution.  */
  sbitmap_vector_ones (avout, n_basic_blocks);

  /* Put every block on the worklist; this is necessary because of the
     optimistic initialization of AVOUT above.  */
  for (bb = 0; bb < n_basic_blocks; bb++)
    {
      *qin++ = BASIC_BLOCK (bb);
      BASIC_BLOCK (bb)->aux = BASIC_BLOCK (bb);
    }
  
  qin = worklist;
  qend = &worklist[n_basic_blocks];
  qlen = n_basic_blocks;

  /* Mark blocks which are successors of the entry block so that we
     can easily identify them below.  */
  for (e = ENTRY_BLOCK_PTR->succ; e; e = e->succ_next)
    e->dest->aux = ENTRY_BLOCK_PTR;

  /* Iterate until the worklist is empty.  */
  while (qlen)
    {
      /* Take the first entry off the worklist.  */
      basic_block b = *qout++;
      bb = b->index;
      qlen--;

      if (qout >= qend)
        qout = worklist;

      /* If one of the predecessor blocks is the ENTRY block, then the
	 intersection of avouts is the null set.  We can identify such blocks
	 by the special value in the AUX field in the block structure.  */
      if (b->aux == ENTRY_BLOCK_PTR)
	/* Do not clear the aux field for blocks which are successors of the
	   ENTRY block.  That way we never add then to the worklist again.  */
	sbitmap_zero (avin[bb]);
      else
	{
	  /* Clear the aux field of this block so that it can be added to
	     the worklist again if necessary.  */
	  b->aux = NULL;
	  sbitmap_intersection_of_preds (avin[bb], avout, bb);
	}

      if (sbitmap_union_of_diff (avout[bb], avloc[bb], avin[bb], kill[bb]))
	/* If the out state of this block changed, then we need
	   to add the successors of this block to the worklist
	   if they are not already on the worklist.  */
	for (e = b->succ; e; e = e->succ_next)
	  if (!e->dest->aux && e->dest != EXIT_BLOCK_PTR)
	    {
	      *qin++ = e->dest;
	      e->dest->aux = e;
	      qlen++;

	      if (qin >= qend)
	        qin = worklist;
	    }
    }

  free (worklist);
}

/* Compute the farthest vector for edge based lcm.  */

static void
compute_farthest (edge_list, n_exprs, st_avout, st_avin, st_antin, 
		  kill, farthest)
     struct edge_list *edge_list;
     int n_exprs;
     sbitmap *st_avout, *st_avin, *st_antin, *kill, *farthest;
{
  sbitmap difference, temp_bitmap;
  int x, num_edges; 
  basic_block pred, succ;

  num_edges = NUM_EDGES (edge_list);

  difference = sbitmap_alloc (n_exprs);
  temp_bitmap = sbitmap_alloc (n_exprs);

  for (x = 0; x < num_edges; x++)
    {
      pred = INDEX_EDGE_PRED_BB (edge_list, x);
      succ = INDEX_EDGE_SUCC_BB (edge_list, x);
      if (succ == EXIT_BLOCK_PTR)
	sbitmap_copy (farthest[x], st_avout[pred->index]);
      else
	{
	  if (pred == ENTRY_BLOCK_PTR)
	    sbitmap_zero (farthest[x]);
	  else
	    {
	      sbitmap_difference (difference, st_avout[pred->index], 
				  st_antin[succ->index]);
	      sbitmap_not (temp_bitmap, st_avin[succ->index]);
	      sbitmap_a_and_b_or_c (farthest[x], difference, 
				    kill[succ->index], temp_bitmap);
	    }
	}
    }

  free (temp_bitmap);
  free (difference);
}

/* Compute nearer and nearerout vectors for edge based lcm.

   This is the mirror of compute_laterin, additional comments on the
   implementation can be found before compute_laterin.  */

static void
compute_nearerout (edge_list, farthest, st_avloc, nearer, nearerout)
     struct edge_list *edge_list;
     sbitmap *farthest, *st_avloc, *nearer, *nearerout;
{
  int bb, num_edges, i;
  edge e;
  basic_block *worklist, *tos;

  num_edges = NUM_EDGES (edge_list);

  /* Allocate a worklist array/queue.  Entries are only added to the
     list if they were not already on the list.  So the size is
     bounded by the number of basic blocks.  */
  tos = worklist
    = (basic_block *) xmalloc (sizeof (basic_block) * (n_basic_blocks + 1));

  /* Initialize NEARER for each edge and build a mapping from an edge to
     its index.  */
  for (i = 0; i < num_edges; i++)
    INDEX_EDGE (edge_list, i)->aux = (void *) (size_t) i;

  /* We want a maximal solution.  */
  sbitmap_vector_ones (nearer, num_edges);

  /* Note that even though we want an optimistic setting of NEARER, we
     do not want to be overly optimistic.  Consider an incoming edge to
     the exit block.  That edge should always have a NEARER value the
     same as FARTHEST for that edge.  */
  for (e = EXIT_BLOCK_PTR->pred; e; e = e->pred_next)
    sbitmap_copy (nearer[(size_t)e->aux], farthest[(size_t)e->aux]);

  /* Add all the blocks to the worklist.  This prevents an early exit
     from the loop given our optimistic initialization of NEARER.  */
  for (bb = 0; bb < n_basic_blocks; bb++)
    {
      basic_block b = BASIC_BLOCK (bb);
      *tos++ = b;
      b->aux = b;
    }
 
  /* Iterate until the worklist is empty.  */
  while (tos != worklist)
    {
      /* Take the first entry off the worklist.  */
      basic_block b = *--tos;
      b->aux = NULL;

      /* Compute the intersection of NEARER for each outgoing edge from B.  */
      bb = b->index;
      sbitmap_ones (nearerout[bb]);
      for (e = b->succ; e != NULL; e = e->succ_next)
	sbitmap_a_and_b (nearerout[bb], nearerout[bb],
			 nearer[(size_t) e->aux]);

      /* Calculate NEARER for all incoming edges.  */
      for (e = b->pred; e != NULL; e = e->pred_next)
	if (sbitmap_union_of_diff (nearer[(size_t) e->aux],
				   farthest[(size_t) e->aux],
				   nearerout[e->dest->index],
				   st_avloc[e->dest->index])
	    /* If NEARER for an incoming edge was changed, then we need
	       to add the source of the incoming edge to the worklist.  */
	    && e->src != ENTRY_BLOCK_PTR && e->src->aux == 0)
	  {
	    *tos++ = e->src;
	    e->src->aux = e;
	  }
    }

  /* Computation of insertion and deletion points requires computing NEAREROUT
     for the ENTRY block.  We allocated an extra entry in the NEAREROUT array
     for just this purpose.  */
  sbitmap_ones (nearerout[n_basic_blocks]);
  for (e = ENTRY_BLOCK_PTR->succ; e != NULL; e = e->succ_next)
    sbitmap_a_and_b (nearerout[n_basic_blocks],
		     nearerout[n_basic_blocks],
		     nearer[(size_t) e->aux]);

  free (tos);
}

/* Compute the insertion and deletion points for edge based LCM.  */

static void
compute_rev_insert_delete (edge_list, st_avloc, nearer, nearerout,
			   insert, delete)
     struct edge_list *edge_list;
     sbitmap *st_avloc, *nearer, *nearerout, *insert, *delete;
{
  int x;

  for (x = 0; x < n_basic_blocks; x++)
    sbitmap_difference (delete[x], st_avloc[x], nearerout[x]);
     
  for (x = 0; x < NUM_EDGES (edge_list); x++)
    {
      basic_block b = INDEX_EDGE_PRED_BB (edge_list, x);
      if (b == ENTRY_BLOCK_PTR)
	sbitmap_difference (insert[x], nearer[x], nearerout[n_basic_blocks]);
      else
	sbitmap_difference (insert[x], nearer[x], nearerout[b->index]);
    }
}

/* Given local properties TRANSP, ST_AVLOC, ST_ANTLOC, KILL return the 
   insert and delete vectors for edge based reverse LCM.  Returns an
   edgelist which is used to map the insert vector to what edge
   an expression should be inserted on.  */

struct edge_list *
pre_edge_rev_lcm (file, n_exprs, transp, st_avloc, st_antloc, kill, 
		  insert, delete)
     FILE *file ATTRIBUTE_UNUSED;
     int n_exprs;
     sbitmap *transp;
     sbitmap *st_avloc;
     sbitmap *st_antloc;
     sbitmap *kill;
     sbitmap **insert;
     sbitmap **delete;
{
  sbitmap *st_antin, *st_antout;
  sbitmap *st_avout, *st_avin, *farthest;
  sbitmap *nearer, *nearerout;
  struct edge_list *edge_list;
  int num_edges;

  edge_list = create_edge_list ();
  num_edges = NUM_EDGES (edge_list);

  st_antin = (sbitmap *) sbitmap_vector_alloc (n_basic_blocks, n_exprs);
  st_antout = (sbitmap *) sbitmap_vector_alloc (n_basic_blocks, n_exprs);
  sbitmap_vector_zero (st_antin, n_basic_blocks);
  sbitmap_vector_zero (st_antout, n_basic_blocks);
  compute_antinout_edge (st_antloc, transp, st_antin, st_antout);

  /* Compute global anticipatability.  */
  st_avout = sbitmap_vector_alloc (n_basic_blocks, n_exprs);
  st_avin = sbitmap_vector_alloc (n_basic_blocks, n_exprs);
  compute_available (st_avloc, kill, st_avout, st_avin);

#ifdef LCM_DEBUG_INFO
  if (file)
    {
      fprintf (file, "Edge List:\n");
      verify_edge_list (file, edge_list);
      print_edge_list (file, edge_list);
      dump_sbitmap_vector (file, "transp", "", transp, n_basic_blocks);
      dump_sbitmap_vector (file, "st_avloc", "", st_avloc, n_basic_blocks);
      dump_sbitmap_vector (file, "st_antloc", "", st_antloc, n_basic_blocks);
      dump_sbitmap_vector (file, "st_antin", "", st_antin, n_basic_blocks);
      dump_sbitmap_vector (file, "st_antout", "", st_antout, n_basic_blocks);
      dump_sbitmap_vector (file, "st_kill", "", kill, n_basic_blocks);
    }
#endif

#ifdef LCM_DEBUG_INFO
  if (file)
    {
      dump_sbitmap_vector (file, "st_avout", "", st_avout, n_basic_blocks);
      dump_sbitmap_vector (file, "st_avin", "", st_avin, n_basic_blocks);
    }
#endif

  /* Compute farthestness.  */
  farthest = sbitmap_vector_alloc (num_edges, n_exprs);
  compute_farthest (edge_list, n_exprs, st_avout, st_avin, st_antin, 
		    kill, farthest);

#ifdef LCM_DEBUG_INFO
  if (file)
    dump_sbitmap_vector (file, "farthest", "", farthest, num_edges);
#endif

  free (st_avin);
  free (st_avout);

  nearer = sbitmap_vector_alloc (num_edges, n_exprs);

  /* Allocate an extra element for the entry block.  */
  nearerout = sbitmap_vector_alloc (n_basic_blocks + 1, n_exprs);
  compute_nearerout (edge_list, farthest, st_avloc, nearer, nearerout);

#ifdef LCM_DEBUG_INFO
  if (file)
    {
      dump_sbitmap_vector (file, "nearerout", "", nearerout, 
			   n_basic_blocks + 1);
      dump_sbitmap_vector (file, "nearer", "", nearer, num_edges);
    }
#endif

  free (farthest);

  *insert = sbitmap_vector_alloc (num_edges, n_exprs);
  *delete = sbitmap_vector_alloc (n_basic_blocks, n_exprs);
  compute_rev_insert_delete (edge_list, st_avloc, nearer, nearerout,
			     *insert, *delete);

  free (nearerout);
  free (nearer);

#ifdef LCM_DEBUG_INFO
  if (file)
    {
      dump_sbitmap_vector (file, "pre_insert_map", "", *insert, num_edges);
      dump_sbitmap_vector (file, "pre_delete_map", "", *delete,
			   n_basic_blocks);
    }
#endif

  return edge_list;
}

/* Mode switching:

   The algorithm for setting the modes consists of scanning the insn list
   and finding all the insns which require a specific mode.  Each insn gets
   a unique struct seginfo element.  These structures are inserted into a list
   for each basic block.  For each entity, there is an array of bb_info over
   the flow graph basic blocks (local var 'bb_info'), and contains a list
   of all insns within that basic block, in the order they are encountered.

   For each entity, any basic block WITHOUT any insns requiring a specific
   mode are given a single entry, without a mode.  (Each basic block
   in the flow graph must have at least one entry in the segment table.)

   The LCM algorithm is then run over the flow graph to determine where to
   place the sets to the highest-priority value in respect of first the first
   insn in any one block.  Any adjustments required to the transparancy
   vectors are made, then the next iteration starts for the next-lower
   priority mode, till for each entity all modes are exhasted.

   More details are located in the code for optimize_mode_switching().  */

/* This structure contains the information for each insn which requires
   either single or double mode to be set.  
   MODE is the mode this insn must be executed in.
   INSN_PTR is the insn to be executed (may be the note that marks the
   beginning of a basic block).
   BBNUM is the flow graph basic block this insn occurs in.
   NEXT is the next insn in the same basic block.  */
struct seginfo 
{
  int mode;
  rtx insn_ptr;
  int bbnum;
  struct seginfo *next;
  HARD_REG_SET regs_live;
};

struct bb_info
{
  struct seginfo *seginfo;
  int computing;
};

/* These bitmaps are used for the LCM algorithm.  */

#ifdef OPTIMIZE_MODE_SWITCHING
static sbitmap *antic;
static sbitmap *transp;
static sbitmap *comp;
static sbitmap *delete;
static sbitmap *insert;

static struct seginfo * new_seginfo PARAMS ((int, rtx, int, HARD_REG_SET));
static void add_seginfo PARAMS ((struct bb_info *, struct seginfo *));
static void reg_dies PARAMS ((rtx, HARD_REG_SET));
static void reg_becomes_live PARAMS ((rtx, rtx, void *));
static void make_preds_opaque PARAMS ((basic_block, int));
#endif

#ifdef OPTIMIZE_MODE_SWITCHING

/* This function will allocate a new BBINFO structure, initialized
   with the MODE, INSN, and basic block BB parameters.  */

static struct seginfo *
new_seginfo (mode, insn, bb, regs_live)
     int mode;
     rtx insn;
     int bb;
     HARD_REG_SET regs_live;
{
  struct seginfo *ptr;
  ptr = xmalloc (sizeof (struct seginfo));
  ptr->mode = mode;
  ptr->insn_ptr = insn;
  ptr->bbnum = bb;
  ptr->next = NULL;
  COPY_HARD_REG_SET (ptr->regs_live, regs_live);
  return ptr;
}

/* Add a seginfo element to the end of a list.  
   HEAD is a pointer to the list beginning.
   INFO is the structure to be linked in.  */

static void
add_seginfo (head, info)
     struct bb_info *head;
     struct seginfo *info;
{
  struct seginfo *ptr;

  if (head->seginfo == NULL)
    head->seginfo = info;
  else
    {
      ptr = head->seginfo;
      while (ptr->next != NULL)
        ptr = ptr->next;
      ptr->next = info;
    }
}

/* Make all predecessors of basic block B opaque, recursively, till we hit
   some that are already non-transparent, or an edge where aux is set; that
   denotes that a mode set is to be done on that edge.
   J is the bit number in the bitmaps that corresponds to the entity that
   we are currently handling mode-switching for.  */

static void
make_preds_opaque (b, j)
     basic_block b;
     int j;
{
  edge e;

  for (e = b->pred; e; e = e->pred_next)
    {
      basic_block pb = e->src;

      if (e->aux || ! TEST_BIT (transp[pb->index], j))
	continue;

      RESET_BIT (transp[pb->index], j);
      make_preds_opaque (pb, j);
    }
}

/* Record in LIVE that register REG died.  */

static void
reg_dies (reg, live)
     rtx reg;
     HARD_REG_SET live;
{
  int regno, nregs;

  if (GET_CODE (reg) != REG)
    return;

  regno = REGNO (reg);
  if (regno < FIRST_PSEUDO_REGISTER)
    for (nregs = HARD_REGNO_NREGS (regno, GET_MODE (reg)) - 1; nregs >= 0;
	 nregs--)
      CLEAR_HARD_REG_BIT (live, regno + nregs);
}

/* Record in LIVE that register REG became live.
   This is called via note_stores.  */

static void
reg_becomes_live (reg, setter, live)
     rtx reg;
     rtx setter ATTRIBUTE_UNUSED;
     void *live;
{
  int regno, nregs;

  if (GET_CODE (reg) == SUBREG)
    reg = SUBREG_REG (reg);

  if (GET_CODE (reg) != REG)
    return;

  regno = REGNO (reg);
  if (regno < FIRST_PSEUDO_REGISTER)
    for (nregs = HARD_REGNO_NREGS (regno, GET_MODE (reg)) - 1; nregs >= 0;
	 nregs--)
      SET_HARD_REG_BIT (* (HARD_REG_SET *) live, regno + nregs);
}

/* Find all insns that need a particular mode setting, and insert the
   necessary mode switches.  Return true if we did work.  */

int
optimize_mode_switching (file)
     FILE *file;
{
  rtx insn;
  int bb, e;
  edge eg;
  int need_commit = 0;
  sbitmap *kill;
  struct edge_list *edge_list;
  static int num_modes[] = NUM_MODES_FOR_MODE_SWITCHING;
#define N_ENTITIES (sizeof num_modes / sizeof (int))
  int entity_map[N_ENTITIES];
  struct bb_info *bb_info[N_ENTITIES];
  int i, j;
  int n_entities;
  int max_num_modes = 0;

#ifdef NORMAL_MODE
  /* Increment n_basic_blocks before allocating bb_info.  */
  n_basic_blocks++;
#endif

  for (e = N_ENTITIES - 1, n_entities = 0; e >= 0; e--)
    if (OPTIMIZE_MODE_SWITCHING (e))
      {
	/* Create the list of segments within each basic block.  */
	bb_info[n_entities]
	  = (struct bb_info *) xcalloc (n_basic_blocks, sizeof **bb_info);
	entity_map[n_entities++] = e;
	if (num_modes[e] > max_num_modes)
	  max_num_modes = num_modes[e];
      }

#ifdef NORMAL_MODE
  /* Decrement it back in case we return below.  */
  n_basic_blocks--;
#endif

  if (! n_entities)
    return 0;

#ifdef NORMAL_MODE
  /* We're going to pretend the EXIT_BLOCK is a regular basic block,
     so that switching back to normal mode when entering the
     EXIT_BLOCK isn't optimized away.  We do this by incrementing the
     basic block count, growing the VARRAY of basic_block_info and
     appending the EXIT_BLOCK_PTR to it.  */
  n_basic_blocks++;
  if (VARRAY_SIZE (basic_block_info) < n_basic_blocks)
    VARRAY_GROW (basic_block_info, n_basic_blocks);
  BASIC_BLOCK (n_basic_blocks - 1) = EXIT_BLOCK_PTR;
  EXIT_BLOCK_PTR->index = n_basic_blocks - 1;
#endif

  /* Create the bitmap vectors.  */

  antic = sbitmap_vector_alloc (n_basic_blocks, n_entities);
  transp = sbitmap_vector_alloc (n_basic_blocks, n_entities);
  comp = sbitmap_vector_alloc (n_basic_blocks, n_entities);

  sbitmap_vector_ones (transp, n_basic_blocks);

  for (j = n_entities - 1; j >= 0; j--)
    {
      int e = entity_map[j];
      int no_mode = num_modes[e];
      struct bb_info *info = bb_info[j];

      /* Determine what the first use (if any) need for a mode of entity E is.
	 This will be the mode that is anticipatable for this block.
	 Also compute the initial transparency settings.  */
      for (bb = 0 ; bb < n_basic_blocks; bb++)
	{
	  struct seginfo *ptr;
	  int last_mode = no_mode;
	  HARD_REG_SET live_now;

	  REG_SET_TO_HARD_REG_SET (live_now,
				   BASIC_BLOCK (bb)->global_live_at_start);
	  for (insn = BLOCK_HEAD (bb); 
	       insn != NULL && insn != NEXT_INSN (BLOCK_END (bb));
	       insn = NEXT_INSN (insn))
	    {
	      if (INSN_P (insn))
		{
		  int mode = MODE_NEEDED (e, insn);
		  rtx link;

		  if (mode != no_mode && mode != last_mode)
		    {
		      last_mode = mode;
		      ptr = new_seginfo (mode, insn, bb, live_now);
		      add_seginfo (info + bb, ptr);
		      RESET_BIT (transp[bb], j);
		    }

		  /* Update LIVE_NOW.  */
		  for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
		    if (REG_NOTE_KIND (link) == REG_DEAD)
		      reg_dies (XEXP (link, 0), live_now);

		  note_stores (PATTERN (insn), reg_becomes_live, &live_now);
		  for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
		    if (REG_NOTE_KIND (link) == REG_UNUSED)
		      reg_dies (XEXP (link, 0), live_now);
		}
	    }

	  info[bb].computing = last_mode;
	  /* Check for blocks without ANY mode requirements.  */
	  if (last_mode == no_mode)
	    {
	      ptr = new_seginfo (no_mode, insn, bb, live_now);
	      add_seginfo (info + bb, ptr);
	    }
	}
#ifdef NORMAL_MODE
      {
	int mode = NORMAL_MODE (e);

	if (mode != no_mode)
	  {
	    for (eg = ENTRY_BLOCK_PTR->succ; eg; eg = eg->succ_next)
	      {
		bb = eg->dest->index;

	        /* By always making this nontransparent, we save
		   an extra check in make_preds_opaque.  We also
		   need this to avoid confusing pre_edge_lcm when
		   antic is cleared but transp and comp are set.  */
		RESET_BIT (transp[bb], j);

		/* If the block already has MODE, pretend it
		   has none (because we don't need to set it),
		   but retain whatever mode it computes.  */
		if (info[bb].seginfo->mode == mode)
		  info[bb].seginfo->mode = no_mode;

		/* Insert a fake computing definition of MODE into entry
		   blocks which compute no mode. This represents the mode on
		   entry.  */
		else if (info[bb].computing == no_mode)
		  {
		    info[bb].computing = mode;
		    info[bb].seginfo->mode = no_mode;
		  }
	      }

	    bb = n_basic_blocks - 1;
	    info[bb].seginfo->mode = mode;
	  }
      }
#endif /* NORMAL_MODE */
    }

  kill = sbitmap_vector_alloc (n_basic_blocks, n_entities);
  for (i = 0; i < max_num_modes; i++)
    {
      int current_mode[N_ENTITIES];

      /* Set the anticipatable and computing arrays.  */
      sbitmap_vector_zero (antic, n_basic_blocks);
      sbitmap_vector_zero (comp, n_basic_blocks);
      for (j = n_entities - 1; j >= 0; j--)
	{
	  int m = current_mode[j] = MODE_PRIORITY_TO_MODE (entity_map[j], i);
	  struct bb_info *info = bb_info[j];
	  
	  for (bb = 0 ; bb < n_basic_blocks; bb++)
	    {
	      if (info[bb].seginfo->mode == m)
		SET_BIT (antic[bb], j);

	      if (info[bb].computing == m)
		SET_BIT (comp[bb], j);
	    }
	}

      /* Calculate the optimal locations for the
	 placement mode switches to modes with priority I.  */

      for (bb = n_basic_blocks - 1; bb >= 0; bb--)
	sbitmap_not (kill[bb], transp[bb]);
      edge_list = pre_edge_lcm (file, 1, transp, comp, antic,
				kill, &insert, &delete);

      for (j = n_entities - 1; j >= 0; j--)
	{
	  /* Insert all mode sets that have been inserted by lcm.  */
	  int no_mode = num_modes[entity_map[j]];

	  /* Wherever we have moved a mode setting upwards in the flow graph,
	     the blocks between the new setting site and the now redundant
	     computation ceases to be transparent for any lower-priority
	     mode of the same entity.  First set the aux field of each
	     insertion site edge non-transparent, then propagate the new
	     non-transparency from the redundant computation upwards till
	     we hit an insertion site or an already non-transparent block.  */
	  for (e = NUM_EDGES (edge_list) - 1; e >= 0; e--)
	    {
	      edge eg = INDEX_EDGE (edge_list, e);
	      int mode;
	      basic_block src_bb;
	      HARD_REG_SET live_at_edge;
	      rtx mode_set;

	      eg->aux = 0;

	      if (! TEST_BIT (insert[e], j))
		continue;

	      eg->aux = (void *)1;

	      mode = current_mode[j];
	      src_bb = eg->src;

	      REG_SET_TO_HARD_REG_SET (live_at_edge,
				       src_bb->global_live_at_end);

	      start_sequence ();
	      EMIT_MODE_SET (entity_map[j], mode, live_at_edge);
	      mode_set = gen_sequence ();
	      end_sequence ();

	      /* If this is an abnormal edge, we'll insert at the end
		 of the previous block.  */
	      if (eg->flags & EDGE_ABNORMAL)
		{
		  if (GET_CODE (src_bb->end) == JUMP_INSN)
		    emit_insn_before (mode_set, src_bb->end);
		  /* It doesn't make sense to switch to normal mode
		     after a CALL_INSN, so we're going to abort if we
		     find one.  The cases in which a CALL_INSN may
		     have an abnormal edge are sibcalls and EH edges.
		     In the case of sibcalls, the dest basic-block is
		     the EXIT_BLOCK, that runs in normal mode; it is
		     assumed that a sibcall insn requires normal mode
		     itself, so no mode switch would be required after
		     the call (it wouldn't make sense, anyway).  In
		     the case of EH edges, EH entry points also start
		     in normal mode, so a similar reasoning applies.  */
		  else if (GET_CODE (src_bb->end) == INSN)
		    src_bb->end = emit_insn_after (mode_set, src_bb->end);
		  else
		    abort ();
		  bb_info[j][src_bb->index].computing = mode;
		  RESET_BIT (transp[src_bb->index], j);
		}
	      else
		{
		  need_commit = 1;
		  insert_insn_on_edge (mode_set, eg);
		}
	    }

	  for (bb = n_basic_blocks - 1; bb >= 0; bb--)
	    if (TEST_BIT (delete[bb], j))
	      {
		make_preds_opaque (BASIC_BLOCK (bb), j);
		/* Cancel the 'deleted' mode set.  */
		bb_info[j][bb].seginfo->mode = no_mode;
	      }
	}

      free_edge_list (edge_list);
    }

#ifdef NORMAL_MODE
  /* Restore the special status of EXIT_BLOCK.  */
  n_basic_blocks--;
  VARRAY_POP (basic_block_info);
  EXIT_BLOCK_PTR->index = EXIT_BLOCK;
#endif
  
  /* Now output the remaining mode sets in all the segments.  */
  for (j = n_entities - 1; j >= 0; j--)
    {
      int no_mode = num_modes[entity_map[j]];

#ifdef NORMAL_MODE
      if (bb_info[j][n_basic_blocks].seginfo->mode != no_mode)
	{
	  edge eg;
	  struct seginfo *ptr = bb_info[j][n_basic_blocks].seginfo;

	  for (eg = EXIT_BLOCK_PTR->pred; eg; eg = eg->pred_next)
	    {
	      rtx mode_set;

	      if (bb_info[j][eg->src->index].computing == ptr->mode)
		continue;

	      start_sequence ();
	      EMIT_MODE_SET (entity_map[j], ptr->mode, ptr->regs_live);
	      mode_set = gen_sequence ();
	      end_sequence ();

	      /* If this is an abnormal edge, we'll insert at the end of the
		 previous block.  */
	      if (eg->flags & EDGE_ABNORMAL)
		{
		  if (GET_CODE (eg->src->end) == JUMP_INSN)
		    emit_insn_before (mode_set, eg->src->end);
		  else if (GET_CODE (eg->src->end) == INSN)
		    eg->src->end = emit_insn_after (mode_set, eg->src->end);
		  else
		    abort ();
		}
	      else
		{
		  need_commit = 1;
		  insert_insn_on_edge (mode_set, eg);
		}
	    }
	  
	}
#endif

      for (bb = n_basic_blocks - 1; bb >= 0; bb--)
	{
	  struct seginfo *ptr, *next;
	  for (ptr = bb_info[j][bb].seginfo; ptr; ptr = next)
	    {
	      next = ptr->next;
	      if (ptr->mode != no_mode)
		{
		  rtx mode_set;

		  start_sequence ();
		  EMIT_MODE_SET (entity_map[j], ptr->mode, ptr->regs_live);
		  mode_set = gen_sequence ();
		  end_sequence ();

		  if (GET_CODE (ptr->insn_ptr) == NOTE
		      && (NOTE_LINE_NUMBER (ptr->insn_ptr)
			  == NOTE_INSN_BASIC_BLOCK))
		    emit_block_insn_after (mode_set, ptr->insn_ptr,
    		                           BASIC_BLOCK (ptr->bbnum));
		  else
		    emit_block_insn_before (mode_set, ptr->insn_ptr,
					    BASIC_BLOCK (ptr->bbnum));
		}

	      free (ptr);
	    }
	}

      free (bb_info[j]);
    }

  /* Finished. Free up all the things we've allocated.  */
  
  sbitmap_vector_free (kill);
  sbitmap_vector_free (antic);
  sbitmap_vector_free (transp);
  sbitmap_vector_free (comp);
  sbitmap_vector_free (delete);
  sbitmap_vector_free (insert);

  if (need_commit)
    commit_edge_insertions ();

  /* Ideally we'd figure out what blocks were affected and start from
     there, but this is enormously complicated by commit_edge_insertions,
     which would screw up any indicies we'd collected, and also need to
     be involved in the update.  Bail and recompute global life info for
     everything.  */

  allocate_reg_life_data ();
  update_life_info (NULL, UPDATE_LIFE_GLOBAL_RM_NOTES,
		    (PROP_DEATH_NOTES | PROP_KILL_DEAD_CODE
		     | PROP_SCAN_DEAD_CODE | PROP_REG_INFO));

  return 1;
}
#endif /* OPTIMIZE_MODE_SWITCHING */
OpenPOWER on IntegriCloud