aboutsummaryrefslogtreecommitdiffstats
path: root/gcc-4.9/gcc/jump.c
blob: e6dabd05c5c3cf6429cf82804f00eed4a2ed6f72 (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
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
1922
1923
1924
1925
1926
1927
1928
1929
1930
1931
1932
1933
/* Optimize jump instructions, for GNU compiler.
   Copyright (C) 1987-2014 Free Software Foundation, Inc.

This file is part of GCC.

GCC 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 3, or (at your option) any later
version.

GCC 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 GCC; see the file COPYING3.  If not see
<http://www.gnu.org/licenses/>.  */

/* This is the pathetic reminder of old fame of the jump-optimization pass
   of the compiler.  Now it contains basically a set of utility functions to
   operate with jumps.

   Each CODE_LABEL has a count of the times it is used
   stored in the LABEL_NUSES internal field, and each JUMP_INSN
   has one label that it refers to stored in the
   JUMP_LABEL internal field.  With this we can detect labels that
   become unused because of the deletion of all the jumps that
   formerly used them.  The JUMP_LABEL info is sometimes looked
   at by later passes.  For return insns, it contains either a
   RETURN or a SIMPLE_RETURN rtx.

   The subroutines redirect_jump and invert_jump are used
   from other passes as well.  */

#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"
#include "rtl.h"
#include "tm_p.h"
#include "flags.h"
#include "hard-reg-set.h"
#include "regs.h"
#include "insn-config.h"
#include "insn-attr.h"
#include "recog.h"
#include "function.h"
#include "basic-block.h"
#include "expr.h"
#include "except.h"
#include "diagnostic-core.h"
#include "reload.h"
#include "predict.h"
#include "tree-pass.h"
#include "target.h"

/* Optimize jump y; x: ... y: jumpif... x?
   Don't know if it is worth bothering with.  */
/* Optimize two cases of conditional jump to conditional jump?
   This can never delete any instruction or make anything dead,
   or even change what is live at any point.
   So perhaps let combiner do it.  */

static void init_label_info (rtx);
static void mark_all_labels (rtx);
static void mark_jump_label_1 (rtx, rtx, bool, bool);
static void mark_jump_label_asm (rtx, rtx);
static void redirect_exp_1 (rtx *, rtx, rtx, rtx);
static int invert_exp_1 (rtx, rtx);
static int returnjump_p_1 (rtx *, void *);

/* Worker for rebuild_jump_labels and rebuild_jump_labels_chain.  */
static void
rebuild_jump_labels_1 (rtx f, bool count_forced)
{
  rtx insn;

  timevar_push (TV_REBUILD_JUMP);
  init_label_info (f);
  mark_all_labels (f);

  /* Keep track of labels used from static data; we don't track them
     closely enough to delete them here, so make sure their reference
     count doesn't drop to zero.  */

  if (count_forced)
    for (insn = forced_labels; insn; insn = XEXP (insn, 1))
      if (LABEL_P (XEXP (insn, 0)))
	LABEL_NUSES (XEXP (insn, 0))++;
  timevar_pop (TV_REBUILD_JUMP);
}

/* This function rebuilds the JUMP_LABEL field and REG_LABEL_TARGET
   notes in jumping insns and REG_LABEL_OPERAND notes in non-jumping
   instructions and jumping insns that have labels as operands
   (e.g. cbranchsi4).  */
void
rebuild_jump_labels (rtx f)
{
  rebuild_jump_labels_1 (f, true);
}

/* This function is like rebuild_jump_labels, but doesn't run over
   forced_labels.  It can be used on insn chains that aren't the 
   main function chain.  */
void
rebuild_jump_labels_chain (rtx chain)
{
  rebuild_jump_labels_1 (chain, false);
}

/* Some old code expects exactly one BARRIER as the NEXT_INSN of a
   non-fallthru insn.  This is not generally true, as multiple barriers
   may have crept in, or the BARRIER may be separated from the last
   real insn by one or more NOTEs.

   This simple pass moves barriers and removes duplicates so that the
   old code is happy.
 */
static unsigned int
cleanup_barriers (void)
{
  rtx insn, next, prev;
  for (insn = get_insns (); insn; insn = next)
    {
      next = NEXT_INSN (insn);
      if (BARRIER_P (insn))
	{
	  prev = prev_nonnote_insn (insn);
	  if (!prev)
	    continue;
	  if (BARRIER_P (prev))
	    delete_insn (insn);
	  else if (prev != PREV_INSN (insn))
	    reorder_insns_nobb (insn, insn, prev);
	}
    }
  return 0;
}

namespace {

const pass_data pass_data_cleanup_barriers =
{
  RTL_PASS, /* type */
  "barriers", /* name */
  OPTGROUP_NONE, /* optinfo_flags */
  false, /* has_gate */
  true, /* has_execute */
  TV_NONE, /* tv_id */
  0, /* properties_required */
  0, /* properties_provided */
  0, /* properties_destroyed */
  0, /* todo_flags_start */
  0, /* todo_flags_finish */
};

class pass_cleanup_barriers : public rtl_opt_pass
{
public:
  pass_cleanup_barriers (gcc::context *ctxt)
    : rtl_opt_pass (pass_data_cleanup_barriers, ctxt)
  {}

  /* opt_pass methods: */
  unsigned int execute () { return cleanup_barriers (); }

}; // class pass_cleanup_barriers

} // anon namespace

rtl_opt_pass *
make_pass_cleanup_barriers (gcc::context *ctxt)
{
  return new pass_cleanup_barriers (ctxt);
}


/* Initialize LABEL_NUSES and JUMP_LABEL fields, add REG_LABEL_TARGET
   for remaining targets for JUMP_P.  Delete any REG_LABEL_OPERAND
   notes whose labels don't occur in the insn any more.  */

static void
init_label_info (rtx f)
{
  rtx insn;

  for (insn = f; insn; insn = NEXT_INSN (insn))
    {
      if (LABEL_P (insn))
	LABEL_NUSES (insn) = (LABEL_PRESERVE_P (insn) != 0);

      /* REG_LABEL_TARGET notes (including the JUMP_LABEL field) are
	 sticky and not reset here; that way we won't lose association
	 with a label when e.g. the source for a target register
	 disappears out of reach for targets that may use jump-target
	 registers.  Jump transformations are supposed to transform
	 any REG_LABEL_TARGET notes.  The target label reference in a
	 branch may disappear from the branch (and from the
	 instruction before it) for other reasons, like register
	 allocation.  */

      if (INSN_P (insn))
	{
	  rtx note, next;

	  for (note = REG_NOTES (insn); note; note = next)
	    {
	      next = XEXP (note, 1);
	      if (REG_NOTE_KIND (note) == REG_LABEL_OPERAND
		  && ! reg_mentioned_p (XEXP (note, 0), PATTERN (insn)))
		remove_note (insn, note);
	    }
	}
    }
}

/* A subroutine of mark_all_labels.  Trivially propagate a simple label
   load into a jump_insn that uses it.  */

static void
maybe_propagate_label_ref (rtx jump_insn, rtx prev_nonjump_insn)
{
  rtx label_note, pc, pc_src;

  pc = pc_set (jump_insn);
  pc_src = pc != NULL ? SET_SRC (pc) : NULL;
  label_note = find_reg_note (prev_nonjump_insn, REG_LABEL_OPERAND, NULL);

  /* If the previous non-jump insn sets something to a label,
     something that this jump insn uses, make that label the primary
     target of this insn if we don't yet have any.  That previous
     insn must be a single_set and not refer to more than one label.
     The jump insn must not refer to other labels as jump targets
     and must be a plain (set (pc) ...), maybe in a parallel, and
     may refer to the item being set only directly or as one of the
     arms in an IF_THEN_ELSE.  */

  if (label_note != NULL && pc_src != NULL)
    {
      rtx label_set = single_set (prev_nonjump_insn);
      rtx label_dest = label_set != NULL ? SET_DEST (label_set) : NULL;

      if (label_set != NULL
	  /* The source must be the direct LABEL_REF, not a
	     PLUS, UNSPEC, IF_THEN_ELSE etc.  */
	  && GET_CODE (SET_SRC (label_set)) == LABEL_REF
	  && (rtx_equal_p (label_dest, pc_src)
	      || (GET_CODE (pc_src) == IF_THEN_ELSE
		  && (rtx_equal_p (label_dest, XEXP (pc_src, 1))
		      || rtx_equal_p (label_dest, XEXP (pc_src, 2))))))
	{
	  /* The CODE_LABEL referred to in the note must be the
	     CODE_LABEL in the LABEL_REF of the "set".  We can
	     conveniently use it for the marker function, which
	     requires a LABEL_REF wrapping.  */
	  gcc_assert (XEXP (label_note, 0) == XEXP (SET_SRC (label_set), 0));

	  mark_jump_label_1 (label_set, jump_insn, false, true);

	  gcc_assert (JUMP_LABEL (jump_insn) == XEXP (label_note, 0));
	}
    }
}

/* Mark the label each jump jumps to.
   Combine consecutive labels, and count uses of labels.  */

static void
mark_all_labels (rtx f)
{
  rtx insn;

  if (current_ir_type () == IR_RTL_CFGLAYOUT)
    {
      basic_block bb;
      FOR_EACH_BB_FN (bb, cfun)
	{
	  /* In cfglayout mode, we don't bother with trivial next-insn
	     propagation of LABEL_REFs into JUMP_LABEL.  This will be
	     handled by other optimizers using better algorithms.  */
	  FOR_BB_INSNS (bb, insn)
	    {
	      gcc_assert (! INSN_DELETED_P (insn));
	      if (NONDEBUG_INSN_P (insn))
	        mark_jump_label (PATTERN (insn), insn, 0);
	    }

	  /* In cfglayout mode, there may be non-insns between the
	     basic blocks.  If those non-insns represent tablejump data,
	     they contain label references that we must record.  */
	  for (insn = BB_HEADER (bb); insn; insn = NEXT_INSN (insn))
	    if (JUMP_TABLE_DATA_P (insn))
	      mark_jump_label (PATTERN (insn), insn, 0);
	  for (insn = BB_FOOTER (bb); insn; insn = NEXT_INSN (insn))
	    if (JUMP_TABLE_DATA_P (insn))
	      mark_jump_label (PATTERN (insn), insn, 0);
	}
    }
  else
    {
      rtx prev_nonjump_insn = NULL;
      for (insn = f; insn; insn = NEXT_INSN (insn))
	{
	  if (INSN_DELETED_P (insn))
	    ;
	  else if (LABEL_P (insn))
	    prev_nonjump_insn = NULL;
	  else if (JUMP_TABLE_DATA_P (insn))
	    mark_jump_label (PATTERN (insn), insn, 0);
	  else if (NONDEBUG_INSN_P (insn))
	    {
	      mark_jump_label (PATTERN (insn), insn, 0);
	      if (JUMP_P (insn))
		{
		  if (JUMP_LABEL (insn) == NULL && prev_nonjump_insn != NULL)
		    maybe_propagate_label_ref (insn, prev_nonjump_insn);
		}
	      else
		prev_nonjump_insn = insn;
	    }
	}
    }
}

/* Given a comparison (CODE ARG0 ARG1), inside an insn, INSN, return a code
   of reversed comparison if it is possible to do so.  Otherwise return UNKNOWN.
   UNKNOWN may be returned in case we are having CC_MODE compare and we don't
   know whether it's source is floating point or integer comparison.  Machine
   description should define REVERSIBLE_CC_MODE and REVERSE_CONDITION macros
   to help this function avoid overhead in these cases.  */
enum rtx_code
reversed_comparison_code_parts (enum rtx_code code, const_rtx arg0,
				const_rtx arg1, const_rtx insn)
{
  enum machine_mode mode;

  /* If this is not actually a comparison, we can't reverse it.  */
  if (GET_RTX_CLASS (code) != RTX_COMPARE
      && GET_RTX_CLASS (code) != RTX_COMM_COMPARE)
    return UNKNOWN;

  mode = GET_MODE (arg0);
  if (mode == VOIDmode)
    mode = GET_MODE (arg1);

  /* First see if machine description supplies us way to reverse the
     comparison.  Give it priority over everything else to allow
     machine description to do tricks.  */
  if (GET_MODE_CLASS (mode) == MODE_CC
      && REVERSIBLE_CC_MODE (mode))
    {
#ifdef REVERSE_CONDITION
      return REVERSE_CONDITION (code, mode);
#else
      return reverse_condition (code);
#endif
    }

  /* Try a few special cases based on the comparison code.  */
  switch (code)
    {
    case GEU:
    case GTU:
    case LEU:
    case LTU:
    case NE:
    case EQ:
      /* It is always safe to reverse EQ and NE, even for the floating
	 point.  Similarly the unsigned comparisons are never used for
	 floating point so we can reverse them in the default way.  */
      return reverse_condition (code);
    case ORDERED:
    case UNORDERED:
    case LTGT:
    case UNEQ:
      /* In case we already see unordered comparison, we can be sure to
	 be dealing with floating point so we don't need any more tests.  */
      return reverse_condition_maybe_unordered (code);
    case UNLT:
    case UNLE:
    case UNGT:
    case UNGE:
      /* We don't have safe way to reverse these yet.  */
      return UNKNOWN;
    default:
      break;
    }

  if (GET_MODE_CLASS (mode) == MODE_CC || CC0_P (arg0))
    {
      const_rtx prev;
      /* Try to search for the comparison to determine the real mode.
         This code is expensive, but with sane machine description it
         will be never used, since REVERSIBLE_CC_MODE will return true
         in all cases.  */
      if (! insn)
	return UNKNOWN;

      /* These CONST_CAST's are okay because prev_nonnote_insn just
	 returns its argument and we assign it to a const_rtx
	 variable.  */
      for (prev = prev_nonnote_insn (CONST_CAST_RTX (insn));
	   prev != 0 && !LABEL_P (prev);
	   prev = prev_nonnote_insn (CONST_CAST_RTX (prev)))
	{
	  const_rtx set = set_of (arg0, prev);
	  if (set && GET_CODE (set) == SET
	      && rtx_equal_p (SET_DEST (set), arg0))
	    {
	      rtx src = SET_SRC (set);

	      if (GET_CODE (src) == COMPARE)
		{
		  rtx comparison = src;
		  arg0 = XEXP (src, 0);
		  mode = GET_MODE (arg0);
		  if (mode == VOIDmode)
		    mode = GET_MODE (XEXP (comparison, 1));
		  break;
		}
	      /* We can get past reg-reg moves.  This may be useful for model
	         of i387 comparisons that first move flag registers around.  */
	      if (REG_P (src))
		{
		  arg0 = src;
		  continue;
		}
	    }
	  /* If register is clobbered in some ununderstandable way,
	     give up.  */
	  if (set)
	    return UNKNOWN;
	}
    }

  /* Test for an integer condition, or a floating-point comparison
     in which NaNs can be ignored.  */
  if (CONST_INT_P (arg0)
      || (GET_MODE (arg0) != VOIDmode
	  && GET_MODE_CLASS (mode) != MODE_CC
	  && !HONOR_NANS (mode)))
    return reverse_condition (code);

  return UNKNOWN;
}

/* A wrapper around the previous function to take COMPARISON as rtx
   expression.  This simplifies many callers.  */
enum rtx_code
reversed_comparison_code (const_rtx comparison, const_rtx insn)
{
  if (!COMPARISON_P (comparison))
    return UNKNOWN;
  return reversed_comparison_code_parts (GET_CODE (comparison),
					 XEXP (comparison, 0),
					 XEXP (comparison, 1), insn);
}

/* Return comparison with reversed code of EXP.
   Return NULL_RTX in case we fail to do the reversal.  */
rtx
reversed_comparison (const_rtx exp, enum machine_mode mode)
{
  enum rtx_code reversed_code = reversed_comparison_code (exp, NULL_RTX);
  if (reversed_code == UNKNOWN)
    return NULL_RTX;
  else
    return simplify_gen_relational (reversed_code, mode, VOIDmode,
                                    XEXP (exp, 0), XEXP (exp, 1));
}


/* Given an rtx-code for a comparison, return the code for the negated
   comparison.  If no such code exists, return UNKNOWN.

   WATCH OUT!  reverse_condition is not safe to use on a jump that might
   be acting on the results of an IEEE floating point comparison, because
   of the special treatment of non-signaling nans in comparisons.
   Use reversed_comparison_code instead.  */

enum rtx_code
reverse_condition (enum rtx_code code)
{
  switch (code)
    {
    case EQ:
      return NE;
    case NE:
      return EQ;
    case GT:
      return LE;
    case GE:
      return LT;
    case LT:
      return GE;
    case LE:
      return GT;
    case GTU:
      return LEU;
    case GEU:
      return LTU;
    case LTU:
      return GEU;
    case LEU:
      return GTU;
    case UNORDERED:
      return ORDERED;
    case ORDERED:
      return UNORDERED;

    case UNLT:
    case UNLE:
    case UNGT:
    case UNGE:
    case UNEQ:
    case LTGT:
      return UNKNOWN;

    default:
      gcc_unreachable ();
    }
}

/* Similar, but we're allowed to generate unordered comparisons, which
   makes it safe for IEEE floating-point.  Of course, we have to recognize
   that the target will support them too...  */

enum rtx_code
reverse_condition_maybe_unordered (enum rtx_code code)
{
  switch (code)
    {
    case EQ:
      return NE;
    case NE:
      return EQ;
    case GT:
      return UNLE;
    case GE:
      return UNLT;
    case LT:
      return UNGE;
    case LE:
      return UNGT;
    case LTGT:
      return UNEQ;
    case UNORDERED:
      return ORDERED;
    case ORDERED:
      return UNORDERED;
    case UNLT:
      return GE;
    case UNLE:
      return GT;
    case UNGT:
      return LE;
    case UNGE:
      return LT;
    case UNEQ:
      return LTGT;

    default:
      gcc_unreachable ();
    }
}

/* Similar, but return the code when two operands of a comparison are swapped.
   This IS safe for IEEE floating-point.  */

enum rtx_code
swap_condition (enum rtx_code code)
{
  switch (code)
    {
    case EQ:
    case NE:
    case UNORDERED:
    case ORDERED:
    case UNEQ:
    case LTGT:
      return code;

    case GT:
      return LT;
    case GE:
      return LE;
    case LT:
      return GT;
    case LE:
      return GE;
    case GTU:
      return LTU;
    case GEU:
      return LEU;
    case LTU:
      return GTU;
    case LEU:
      return GEU;
    case UNLT:
      return UNGT;
    case UNLE:
      return UNGE;
    case UNGT:
      return UNLT;
    case UNGE:
      return UNLE;

    default:
      gcc_unreachable ();
    }
}

/* Given a comparison CODE, return the corresponding unsigned comparison.
   If CODE is an equality comparison or already an unsigned comparison,
   CODE is returned.  */

enum rtx_code
unsigned_condition (enum rtx_code code)
{
  switch (code)
    {
    case EQ:
    case NE:
    case GTU:
    case GEU:
    case LTU:
    case LEU:
      return code;

    case GT:
      return GTU;
    case GE:
      return GEU;
    case LT:
      return LTU;
    case LE:
      return LEU;

    default:
      gcc_unreachable ();
    }
}

/* Similarly, return the signed version of a comparison.  */

enum rtx_code
signed_condition (enum rtx_code code)
{
  switch (code)
    {
    case EQ:
    case NE:
    case GT:
    case GE:
    case LT:
    case LE:
      return code;

    case GTU:
      return GT;
    case GEU:
      return GE;
    case LTU:
      return LT;
    case LEU:
      return LE;

    default:
      gcc_unreachable ();
    }
}

/* Return nonzero if CODE1 is more strict than CODE2, i.e., if the
   truth of CODE1 implies the truth of CODE2.  */

int
comparison_dominates_p (enum rtx_code code1, enum rtx_code code2)
{
  /* UNKNOWN comparison codes can happen as a result of trying to revert
     comparison codes.
     They can't match anything, so we have to reject them here.  */
  if (code1 == UNKNOWN || code2 == UNKNOWN)
    return 0;

  if (code1 == code2)
    return 1;

  switch (code1)
    {
    case UNEQ:
      if (code2 == UNLE || code2 == UNGE)
	return 1;
      break;

    case EQ:
      if (code2 == LE || code2 == LEU || code2 == GE || code2 == GEU
	  || code2 == ORDERED)
	return 1;
      break;

    case UNLT:
      if (code2 == UNLE || code2 == NE)
	return 1;
      break;

    case LT:
      if (code2 == LE || code2 == NE || code2 == ORDERED || code2 == LTGT)
	return 1;
      break;

    case UNGT:
      if (code2 == UNGE || code2 == NE)
	return 1;
      break;

    case GT:
      if (code2 == GE || code2 == NE || code2 == ORDERED || code2 == LTGT)
	return 1;
      break;

    case GE:
    case LE:
      if (code2 == ORDERED)
	return 1;
      break;

    case LTGT:
      if (code2 == NE || code2 == ORDERED)
	return 1;
      break;

    case LTU:
      if (code2 == LEU || code2 == NE)
	return 1;
      break;

    case GTU:
      if (code2 == GEU || code2 == NE)
	return 1;
      break;

    case UNORDERED:
      if (code2 == NE || code2 == UNEQ || code2 == UNLE || code2 == UNLT
	  || code2 == UNGE || code2 == UNGT)
	return 1;
      break;

    default:
      break;
    }

  return 0;
}

/* Return 1 if INSN is an unconditional jump and nothing else.  */

int
simplejump_p (const_rtx insn)
{
  return (JUMP_P (insn)
	  && GET_CODE (PATTERN (insn)) == SET
	  && GET_CODE (SET_DEST (PATTERN (insn))) == PC
	  && GET_CODE (SET_SRC (PATTERN (insn))) == LABEL_REF);
}

/* Return nonzero if INSN is a (possibly) conditional jump
   and nothing more.

   Use of this function is deprecated, since we need to support combined
   branch and compare insns.  Use any_condjump_p instead whenever possible.  */

int
condjump_p (const_rtx insn)
{
  const_rtx x = PATTERN (insn);

  if (GET_CODE (x) != SET
      || GET_CODE (SET_DEST (x)) != PC)
    return 0;

  x = SET_SRC (x);
  if (GET_CODE (x) == LABEL_REF)
    return 1;
  else
    return (GET_CODE (x) == IF_THEN_ELSE
	    && ((GET_CODE (XEXP (x, 2)) == PC
		 && (GET_CODE (XEXP (x, 1)) == LABEL_REF
		     || ANY_RETURN_P (XEXP (x, 1))))
		|| (GET_CODE (XEXP (x, 1)) == PC
		    && (GET_CODE (XEXP (x, 2)) == LABEL_REF
			|| ANY_RETURN_P (XEXP (x, 2))))));
}

/* Return nonzero if INSN is a (possibly) conditional jump inside a
   PARALLEL.

   Use this function is deprecated, since we need to support combined
   branch and compare insns.  Use any_condjump_p instead whenever possible.  */

int
condjump_in_parallel_p (const_rtx insn)
{
  const_rtx x = PATTERN (insn);

  if (GET_CODE (x) != PARALLEL)
    return 0;
  else
    x = XVECEXP (x, 0, 0);

  if (GET_CODE (x) != SET)
    return 0;
  if (GET_CODE (SET_DEST (x)) != PC)
    return 0;
  if (GET_CODE (SET_SRC (x)) == LABEL_REF)
    return 1;
  if (GET_CODE (SET_SRC (x)) != IF_THEN_ELSE)
    return 0;
  if (XEXP (SET_SRC (x), 2) == pc_rtx
      && (GET_CODE (XEXP (SET_SRC (x), 1)) == LABEL_REF
	  || ANY_RETURN_P (XEXP (SET_SRC (x), 1))))
    return 1;
  if (XEXP (SET_SRC (x), 1) == pc_rtx
      && (GET_CODE (XEXP (SET_SRC (x), 2)) == LABEL_REF
	  || ANY_RETURN_P (XEXP (SET_SRC (x), 2))))
    return 1;
  return 0;
}

/* Return set of PC, otherwise NULL.  */

rtx
pc_set (const_rtx insn)
{
  rtx pat;
  if (!JUMP_P (insn))
    return NULL_RTX;
  pat = PATTERN (insn);

  /* The set is allowed to appear either as the insn pattern or
     the first set in a PARALLEL.  */
  if (GET_CODE (pat) == PARALLEL)
    pat = XVECEXP (pat, 0, 0);
  if (GET_CODE (pat) == SET && GET_CODE (SET_DEST (pat)) == PC)
    return pat;

  return NULL_RTX;
}

/* Return true when insn is an unconditional direct jump,
   possibly bundled inside a PARALLEL.  */

int
any_uncondjump_p (const_rtx insn)
{
  const_rtx x = pc_set (insn);
  if (!x)
    return 0;
  if (GET_CODE (SET_SRC (x)) != LABEL_REF)
    return 0;
  if (find_reg_note (insn, REG_NON_LOCAL_GOTO, NULL_RTX))
    return 0;
  return 1;
}

/* Return true when insn is a conditional jump.  This function works for
   instructions containing PC sets in PARALLELs.  The instruction may have
   various other effects so before removing the jump you must verify
   onlyjump_p.

   Note that unlike condjump_p it returns false for unconditional jumps.  */

int
any_condjump_p (const_rtx insn)
{
  const_rtx x = pc_set (insn);
  enum rtx_code a, b;

  if (!x)
    return 0;
  if (GET_CODE (SET_SRC (x)) != IF_THEN_ELSE)
    return 0;

  a = GET_CODE (XEXP (SET_SRC (x), 1));
  b = GET_CODE (XEXP (SET_SRC (x), 2));

  return ((b == PC && (a == LABEL_REF || a == RETURN || a == SIMPLE_RETURN))
	  || (a == PC
	      && (b == LABEL_REF || b == RETURN || b == SIMPLE_RETURN)));
}

/* Return the label of a conditional jump.  */

rtx
condjump_label (const_rtx insn)
{
  rtx x = pc_set (insn);

  if (!x)
    return NULL_RTX;
  x = SET_SRC (x);
  if (GET_CODE (x) == LABEL_REF)
    return x;
  if (GET_CODE (x) != IF_THEN_ELSE)
    return NULL_RTX;
  if (XEXP (x, 2) == pc_rtx && GET_CODE (XEXP (x, 1)) == LABEL_REF)
    return XEXP (x, 1);
  if (XEXP (x, 1) == pc_rtx && GET_CODE (XEXP (x, 2)) == LABEL_REF)
    return XEXP (x, 2);
  return NULL_RTX;
}

/* Return true if INSN is a (possibly conditional) return insn.  */

static int
returnjump_p_1 (rtx *loc, void *data ATTRIBUTE_UNUSED)
{
  rtx x = *loc;

  if (x == NULL)
    return false;

  switch (GET_CODE (x))
    {
    case RETURN:
    case SIMPLE_RETURN:
    case EH_RETURN:
      return true;

    case SET:
      return SET_IS_RETURN_P (x);

    default:
      return false;
    }
}

/* Return TRUE if INSN is a return jump.  */

int
returnjump_p (rtx insn)
{
  if (!JUMP_P (insn))
    return 0;
  return for_each_rtx (&PATTERN (insn), returnjump_p_1, NULL);
}

/* Return true if INSN is a (possibly conditional) return insn.  */

static int
eh_returnjump_p_1 (rtx *loc, void *data ATTRIBUTE_UNUSED)
{
  return *loc && GET_CODE (*loc) == EH_RETURN;
}

int
eh_returnjump_p (rtx insn)
{
  if (!JUMP_P (insn))
    return 0;
  return for_each_rtx (&PATTERN (insn), eh_returnjump_p_1, NULL);
}

/* Return true if INSN is a jump that only transfers control and
   nothing more.  */

int
onlyjump_p (const_rtx insn)
{
  rtx set;

  if (!JUMP_P (insn))
    return 0;

  set = single_set (insn);
  if (set == NULL)
    return 0;
  if (GET_CODE (SET_DEST (set)) != PC)
    return 0;
  if (side_effects_p (SET_SRC (set)))
    return 0;

  return 1;
}

/* Return true iff INSN is a jump and its JUMP_LABEL is a label, not
   NULL or a return.  */
bool
jump_to_label_p (rtx insn)
{
  return (JUMP_P (insn)
	  && JUMP_LABEL (insn) != NULL && !ANY_RETURN_P (JUMP_LABEL (insn)));
}

#ifdef HAVE_cc0

/* Return nonzero if X is an RTX that only sets the condition codes
   and has no side effects.  */

int
only_sets_cc0_p (const_rtx x)
{
  if (! x)
    return 0;

  if (INSN_P (x))
    x = PATTERN (x);

  return sets_cc0_p (x) == 1 && ! side_effects_p (x);
}

/* Return 1 if X is an RTX that does nothing but set the condition codes
   and CLOBBER or USE registers.
   Return -1 if X does explicitly set the condition codes,
   but also does other things.  */

int
sets_cc0_p (const_rtx x)
{
  if (! x)
    return 0;

  if (INSN_P (x))
    x = PATTERN (x);

  if (GET_CODE (x) == SET && SET_DEST (x) == cc0_rtx)
    return 1;
  if (GET_CODE (x) == PARALLEL)
    {
      int i;
      int sets_cc0 = 0;
      int other_things = 0;
      for (i = XVECLEN (x, 0) - 1; i >= 0; i--)
	{
	  if (GET_CODE (XVECEXP (x, 0, i)) == SET
	      && SET_DEST (XVECEXP (x, 0, i)) == cc0_rtx)
	    sets_cc0 = 1;
	  else if (GET_CODE (XVECEXP (x, 0, i)) == SET)
	    other_things = 1;
	}
      return ! sets_cc0 ? 0 : other_things ? -1 : 1;
    }
  return 0;
}
#endif

/* Find all CODE_LABELs referred to in X, and increment their use
   counts.  If INSN is a JUMP_INSN and there is at least one
   CODE_LABEL referenced in INSN as a jump target, then store the last
   one in JUMP_LABEL (INSN).  For a tablejump, this must be the label
   for the ADDR_VEC.  Store any other jump targets as REG_LABEL_TARGET
   notes.  If INSN is an INSN or a CALL_INSN or non-target operands of
   a JUMP_INSN, and there is at least one CODE_LABEL referenced in
   INSN, add a REG_LABEL_OPERAND note containing that label to INSN.
   For returnjumps, the JUMP_LABEL will also be set as appropriate.

   Note that two labels separated by a loop-beginning note
   must be kept distinct if we have not yet done loop-optimization,
   because the gap between them is where loop-optimize
   will want to move invariant code to.  CROSS_JUMP tells us
   that loop-optimization is done with.  */

void
mark_jump_label (rtx x, rtx insn, int in_mem)
{
  rtx asmop = extract_asm_operands (x);
  if (asmop)
    mark_jump_label_asm (asmop, insn);
  else
    mark_jump_label_1 (x, insn, in_mem != 0,
		       (insn != NULL && x == PATTERN (insn) && JUMP_P (insn)));
}

/* Worker function for mark_jump_label.  IN_MEM is TRUE when X occurs
   within a (MEM ...).  IS_TARGET is TRUE when X is to be treated as a
   jump-target; when the JUMP_LABEL field of INSN should be set or a
   REG_LABEL_TARGET note should be added, not a REG_LABEL_OPERAND
   note.  */

static void
mark_jump_label_1 (rtx x, rtx insn, bool in_mem, bool is_target)
{
  RTX_CODE code = GET_CODE (x);
  int i;
  const char *fmt;

  switch (code)
    {
    case PC:
    case CC0:
    case REG:
    case CLOBBER:
    case CALL:
      return;

    case RETURN:
    case SIMPLE_RETURN:
      if (is_target)
	{
	  gcc_assert (JUMP_LABEL (insn) == NULL || JUMP_LABEL (insn) == x);
	  JUMP_LABEL (insn) = x;
	}
      return;

    case MEM:
      in_mem = true;
      break;

    case SEQUENCE:
      for (i = 0; i < XVECLEN (x, 0); i++)
	mark_jump_label (PATTERN (XVECEXP (x, 0, i)),
			 XVECEXP (x, 0, i), 0);
      return;

    case SYMBOL_REF:
      if (!in_mem)
	return;

      /* If this is a constant-pool reference, see if it is a label.  */
      if (CONSTANT_POOL_ADDRESS_P (x))
	mark_jump_label_1 (get_pool_constant (x), insn, in_mem, is_target);
      break;

      /* Handle operands in the condition of an if-then-else as for a
	 non-jump insn.  */
    case IF_THEN_ELSE:
      if (!is_target)
	break;
      mark_jump_label_1 (XEXP (x, 0), insn, in_mem, false);
      mark_jump_label_1 (XEXP (x, 1), insn, in_mem, true);
      mark_jump_label_1 (XEXP (x, 2), insn, in_mem, true);
      return;

    case LABEL_REF:
      {
	rtx label = XEXP (x, 0);

	/* Ignore remaining references to unreachable labels that
	   have been deleted.  */
	if (NOTE_P (label)
	    && NOTE_KIND (label) == NOTE_INSN_DELETED_LABEL)
	  break;

	gcc_assert (LABEL_P (label));

	/* Ignore references to labels of containing functions.  */
	if (LABEL_REF_NONLOCAL_P (x))
	  break;

	XEXP (x, 0) = label;
	if (! insn || ! INSN_DELETED_P (insn))
	  ++LABEL_NUSES (label);

	if (insn)
	  {
	    if (is_target
		/* Do not change a previous setting of JUMP_LABEL.  If the
		   JUMP_LABEL slot is occupied by a different label,
		   create a note for this label.  */
		&& (JUMP_LABEL (insn) == NULL || JUMP_LABEL (insn) == label))
	      JUMP_LABEL (insn) = label;
	    else
	      {
		enum reg_note kind
		  = is_target ? REG_LABEL_TARGET : REG_LABEL_OPERAND;

		/* Add a REG_LABEL_OPERAND or REG_LABEL_TARGET note
		   for LABEL unless there already is one.  All uses of
		   a label, except for the primary target of a jump,
		   must have such a note.  */
		if (! find_reg_note (insn, kind, label))
		  add_reg_note (insn, kind, label);
	      }
	  }
	return;
      }

    /* Do walk the labels in a vector, but not the first operand of an
       ADDR_DIFF_VEC.  Don't set the JUMP_LABEL of a vector.  */
    case ADDR_VEC:
    case ADDR_DIFF_VEC:
      if (! INSN_DELETED_P (insn))
	{
	  int eltnum = code == ADDR_DIFF_VEC ? 1 : 0;

	  for (i = 0; i < XVECLEN (x, eltnum); i++)
	    mark_jump_label_1 (XVECEXP (x, eltnum, i), NULL_RTX, in_mem,
			       is_target);
	}
      return;

    default:
      break;
    }

  fmt = GET_RTX_FORMAT (code);

  /* The primary target of a tablejump is the label of the ADDR_VEC,
     which is canonically mentioned *last* in the insn.  To get it
     marked as JUMP_LABEL, we iterate over items in reverse order.  */
  for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
    {
      if (fmt[i] == 'e')
	mark_jump_label_1 (XEXP (x, i), insn, in_mem, is_target);
      else if (fmt[i] == 'E')
	{
	  int j;

	  for (j = XVECLEN (x, i) - 1; j >= 0; j--)
	    mark_jump_label_1 (XVECEXP (x, i, j), insn, in_mem,
			       is_target);
	}
    }
}

/* Worker function for mark_jump_label.  Handle asm insns specially.
   In particular, output operands need not be considered so we can
   avoid re-scanning the replicated asm_operand.  Also, the asm_labels
   need to be considered targets.  */

static void
mark_jump_label_asm (rtx asmop, rtx insn)
{
  int i;

  for (i = ASM_OPERANDS_INPUT_LENGTH (asmop) - 1; i >= 0; --i)
    mark_jump_label_1 (ASM_OPERANDS_INPUT (asmop, i), insn, false, false);

  for (i = ASM_OPERANDS_LABEL_LENGTH (asmop) - 1; i >= 0; --i)
    mark_jump_label_1 (ASM_OPERANDS_LABEL (asmop, i), insn, false, true);
}

/* Delete insn INSN from the chain of insns and update label ref counts
   and delete insns now unreachable.

   Returns the first insn after INSN that was not deleted.

   Usage of this instruction is deprecated.  Use delete_insn instead and
   subsequent cfg_cleanup pass to delete unreachable code if needed.  */

rtx
delete_related_insns (rtx insn)
{
  int was_code_label = (LABEL_P (insn));
  rtx note;
  rtx next = NEXT_INSN (insn), prev = PREV_INSN (insn);

  while (next && INSN_DELETED_P (next))
    next = NEXT_INSN (next);

  /* This insn is already deleted => return first following nondeleted.  */
  if (INSN_DELETED_P (insn))
    return next;

  delete_insn (insn);

  /* If instruction is followed by a barrier,
     delete the barrier too.  */

  if (next != 0 && BARRIER_P (next))
    delete_insn (next);

  /* If this is a call, then we have to remove the var tracking note
     for the call arguments.  */

  if (CALL_P (insn)
      || (NONJUMP_INSN_P (insn)
	  && GET_CODE (PATTERN (insn)) == SEQUENCE
	  && CALL_P (XVECEXP (PATTERN (insn), 0, 0))))
    {
      rtx p;

      for (p = next && INSN_DELETED_P (next) ? NEXT_INSN (next) : next;
	   p && NOTE_P (p);
	   p = NEXT_INSN (p))
	if (NOTE_KIND (p) == NOTE_INSN_CALL_ARG_LOCATION)
	  {
	    remove_insn (p);
	    break;
	  }
    }

  /* If deleting a jump, decrement the count of the label,
     and delete the label if it is now unused.  */

  if (jump_to_label_p (insn))
    {
      rtx lab = JUMP_LABEL (insn), lab_next;

      if (LABEL_NUSES (lab) == 0)
	/* This can delete NEXT or PREV,
	   either directly if NEXT is JUMP_LABEL (INSN),
	   or indirectly through more levels of jumps.  */
	delete_related_insns (lab);
      else if (tablejump_p (insn, NULL, &lab_next))
	{
	  /* If we're deleting the tablejump, delete the dispatch table.
	     We may not be able to kill the label immediately preceding
	     just yet, as it might be referenced in code leading up to
	     the tablejump.  */
	  delete_related_insns (lab_next);
	}
    }

  /* Likewise if we're deleting a dispatch table.  */

  if (JUMP_TABLE_DATA_P (insn))
    {
      rtx pat = PATTERN (insn);
      int i, diff_vec_p = GET_CODE (pat) == ADDR_DIFF_VEC;
      int len = XVECLEN (pat, diff_vec_p);

      for (i = 0; i < len; i++)
	if (LABEL_NUSES (XEXP (XVECEXP (pat, diff_vec_p, i), 0)) == 0)
	  delete_related_insns (XEXP (XVECEXP (pat, diff_vec_p, i), 0));
      while (next && INSN_DELETED_P (next))
	next = NEXT_INSN (next);
      return next;
    }

  /* Likewise for any JUMP_P / INSN / CALL_INSN with a
     REG_LABEL_OPERAND or REG_LABEL_TARGET note.  */
  if (INSN_P (insn))
    for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
      if ((REG_NOTE_KIND (note) == REG_LABEL_OPERAND
	   || REG_NOTE_KIND (note) == REG_LABEL_TARGET)
	  /* This could also be a NOTE_INSN_DELETED_LABEL note.  */
	  && LABEL_P (XEXP (note, 0)))
	if (LABEL_NUSES (XEXP (note, 0)) == 0)
	  delete_related_insns (XEXP (note, 0));

  while (prev && (INSN_DELETED_P (prev) || NOTE_P (prev)))
    prev = PREV_INSN (prev);

  /* If INSN was a label and a dispatch table follows it,
     delete the dispatch table.  The tablejump must have gone already.
     It isn't useful to fall through into a table.  */

  if (was_code_label
      && NEXT_INSN (insn) != 0
      && JUMP_TABLE_DATA_P (NEXT_INSN (insn)))
    next = delete_related_insns (NEXT_INSN (insn));

  /* If INSN was a label, delete insns following it if now unreachable.  */

  if (was_code_label && prev && BARRIER_P (prev))
    {
      enum rtx_code code;
      while (next)
	{
	  code = GET_CODE (next);
	  if (code == NOTE)
	    next = NEXT_INSN (next);
	  /* Keep going past other deleted labels to delete what follows.  */
	  else if (code == CODE_LABEL && INSN_DELETED_P (next))
	    next = NEXT_INSN (next);
	  /* Keep the (use (insn))s created by dbr_schedule, which needs
	     them in order to track liveness relative to a previous
	     barrier.  */
	  else if (INSN_P (next)
		   && GET_CODE (PATTERN (next)) == USE
		   && INSN_P (XEXP (PATTERN (next), 0)))
	    next = NEXT_INSN (next);
	  else if (code == BARRIER || INSN_P (next))
	    /* Note: if this deletes a jump, it can cause more
	       deletion of unreachable code, after a different label.
	       As long as the value from this recursive call is correct,
	       this invocation functions correctly.  */
	    next = delete_related_insns (next);
	  else
	    break;
	}
    }

  /* I feel a little doubtful about this loop,
     but I see no clean and sure alternative way
     to find the first insn after INSN that is not now deleted.
     I hope this works.  */
  while (next && INSN_DELETED_P (next))
    next = NEXT_INSN (next);
  return next;
}

/* Delete a range of insns from FROM to TO, inclusive.
   This is for the sake of peephole optimization, so assume
   that whatever these insns do will still be done by a new
   peephole insn that will replace them.  */

void
delete_for_peephole (rtx from, rtx to)
{
  rtx insn = from;

  while (1)
    {
      rtx next = NEXT_INSN (insn);
      rtx prev = PREV_INSN (insn);

      if (!NOTE_P (insn))
	{
	  INSN_DELETED_P (insn) = 1;

	  /* Patch this insn out of the chain.  */
	  /* We don't do this all at once, because we
	     must preserve all NOTEs.  */
	  if (prev)
	    NEXT_INSN (prev) = next;

	  if (next)
	    PREV_INSN (next) = prev;
	}

      if (insn == to)
	break;
      insn = next;
    }

  /* Note that if TO is an unconditional jump
     we *do not* delete the BARRIER that follows,
     since the peephole that replaces this sequence
     is also an unconditional jump in that case.  */
}

/* A helper function for redirect_exp_1; examines its input X and returns
   either a LABEL_REF around a label, or a RETURN if X was NULL.  */
static rtx
redirect_target (rtx x)
{
  if (x == NULL_RTX)
    return ret_rtx;
  if (!ANY_RETURN_P (x))
    return gen_rtx_LABEL_REF (Pmode, x);
  return x;
}

/* Throughout LOC, redirect OLABEL to NLABEL.  Treat null OLABEL or
   NLABEL as a return.  Accrue modifications into the change group.  */

static void
redirect_exp_1 (rtx *loc, rtx olabel, rtx nlabel, rtx insn)
{
  rtx x = *loc;
  RTX_CODE code = GET_CODE (x);
  int i;
  const char *fmt;

  if ((code == LABEL_REF && XEXP (x, 0) == olabel)
      || x == olabel)
    {
      x = redirect_target (nlabel);
      if (GET_CODE (x) == LABEL_REF && loc == &PATTERN (insn))
 	x = gen_rtx_SET (VOIDmode, pc_rtx, x);
      validate_change (insn, loc, x, 1);
      return;
    }

  if (code == SET && SET_DEST (x) == pc_rtx
      && ANY_RETURN_P (nlabel)
      && GET_CODE (SET_SRC (x)) == LABEL_REF
      && XEXP (SET_SRC (x), 0) == olabel)
    {
      validate_change (insn, loc, nlabel, 1);
      return;
    }

  if (code == IF_THEN_ELSE)
    {
      /* Skip the condition of an IF_THEN_ELSE.  We only want to
         change jump destinations, not eventual label comparisons.  */
      redirect_exp_1 (&XEXP (x, 1), olabel, nlabel, insn);
      redirect_exp_1 (&XEXP (x, 2), olabel, nlabel, insn);
      return;
    }

  fmt = GET_RTX_FORMAT (code);
  for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
    {
      if (fmt[i] == 'e')
	redirect_exp_1 (&XEXP (x, i), olabel, nlabel, insn);
      else if (fmt[i] == 'E')
	{
	  int j;
	  for (j = 0; j < XVECLEN (x, i); j++)
	    redirect_exp_1 (&XVECEXP (x, i, j), olabel, nlabel, insn);
	}
    }
}

/* Make JUMP go to NLABEL instead of where it jumps now.  Accrue
   the modifications into the change group.  Return false if we did
   not see how to do that.  */

int
redirect_jump_1 (rtx jump, rtx nlabel)
{
  int ochanges = num_validated_changes ();
  rtx *loc, asmop;

  gcc_assert (nlabel != NULL_RTX);
  asmop = extract_asm_operands (PATTERN (jump));
  if (asmop)
    {
      if (nlabel == NULL)
	return 0;
      gcc_assert (ASM_OPERANDS_LABEL_LENGTH (asmop) == 1);
      loc = &ASM_OPERANDS_LABEL (asmop, 0);
    }
  else if (GET_CODE (PATTERN (jump)) == PARALLEL)
    loc = &XVECEXP (PATTERN (jump), 0, 0);
  else
    loc = &PATTERN (jump);

  redirect_exp_1 (loc, JUMP_LABEL (jump), nlabel, jump);
  return num_validated_changes () > ochanges;
}

/* Make JUMP go to NLABEL instead of where it jumps now.  If the old
   jump target label is unused as a result, it and the code following
   it may be deleted.

   Normally, NLABEL will be a label, but it may also be a RETURN rtx;
   in that case we are to turn the jump into a (possibly conditional)
   return insn.

   The return value will be 1 if the change was made, 0 if it wasn't
   (this can only occur when trying to produce return insns).  */

int
redirect_jump (rtx jump, rtx nlabel, int delete_unused)
{
  rtx olabel = JUMP_LABEL (jump);

  if (!nlabel)
    {
      /* If there is no label, we are asked to redirect to the EXIT block.
	 When before the epilogue is emitted, return/simple_return cannot be
	 created so we return 0 immediately.  After the epilogue is emitted,
	 we always expect a label, either a non-null label, or a
	 return/simple_return RTX.  */

      if (!epilogue_completed)
	return 0;
      gcc_unreachable ();
    }

  if (nlabel == olabel)
    return 1;

  if (! redirect_jump_1 (jump, nlabel) || ! apply_change_group ())
    return 0;

  redirect_jump_2 (jump, olabel, nlabel, delete_unused, 0);
  return 1;
}

/* Fix up JUMP_LABEL and label ref counts after OLABEL has been replaced with
   NLABEL in JUMP.
   If DELETE_UNUSED is positive, delete related insn to OLABEL if its ref
   count has dropped to zero.  */
void
redirect_jump_2 (rtx jump, rtx olabel, rtx nlabel, int delete_unused,
		 int invert)
{
  rtx note;

  gcc_assert (JUMP_LABEL (jump) == olabel);

  /* Negative DELETE_UNUSED used to be used to signalize behavior on
     moving FUNCTION_END note.  Just sanity check that no user still worry
     about this.  */
  gcc_assert (delete_unused >= 0);
  JUMP_LABEL (jump) = nlabel;
  if (!ANY_RETURN_P (nlabel))
    ++LABEL_NUSES (nlabel);

  /* Update labels in any REG_EQUAL note.  */
  if ((note = find_reg_note (jump, REG_EQUAL, NULL_RTX)) != NULL_RTX)
    {
      if (ANY_RETURN_P (nlabel)
	  || (invert && !invert_exp_1 (XEXP (note, 0), jump)))
	remove_note (jump, note);
      else
	{
	  redirect_exp_1 (&XEXP (note, 0), olabel, nlabel, jump);
	  confirm_change_group ();
	}
    }

  /* Handle the case where we had a conditional crossing jump to a return
     label and are now changing it into a direct conditional return.
     The jump is no longer crossing in that case.  */
  if (ANY_RETURN_P (nlabel))
    {
      note = find_reg_note (jump, REG_CROSSING_JUMP, NULL_RTX);
      if (note)
	remove_note (jump, note);
    }

  if (!ANY_RETURN_P (olabel)
      && --LABEL_NUSES (olabel) == 0 && delete_unused > 0
      /* Undefined labels will remain outside the insn stream.  */
      && INSN_UID (olabel))
    delete_related_insns (olabel);
  if (invert)
    invert_br_probabilities (jump);
}

/* Invert the jump condition X contained in jump insn INSN.  Accrue the
   modifications into the change group.  Return nonzero for success.  */
static int
invert_exp_1 (rtx x, rtx insn)
{
  RTX_CODE code = GET_CODE (x);

  if (code == IF_THEN_ELSE)
    {
      rtx comp = XEXP (x, 0);
      rtx tem;
      enum rtx_code reversed_code;

      /* We can do this in two ways:  The preferable way, which can only
	 be done if this is not an integer comparison, is to reverse
	 the comparison code.  Otherwise, swap the THEN-part and ELSE-part
	 of the IF_THEN_ELSE.  If we can't do either, fail.  */

      reversed_code = reversed_comparison_code (comp, insn);

      if (reversed_code != UNKNOWN)
	{
	  validate_change (insn, &XEXP (x, 0),
			   gen_rtx_fmt_ee (reversed_code,
					   GET_MODE (comp), XEXP (comp, 0),
					   XEXP (comp, 1)),
			   1);
	  return 1;
	}

      tem = XEXP (x, 1);
      validate_change (insn, &XEXP (x, 1), XEXP (x, 2), 1);
      validate_change (insn, &XEXP (x, 2), tem, 1);
      return 1;
    }
  else
    return 0;
}

/* Invert the condition of the jump JUMP, and make it jump to label
   NLABEL instead of where it jumps now.  Accrue changes into the
   change group.  Return false if we didn't see how to perform the
   inversion and redirection.  */

int
invert_jump_1 (rtx jump, rtx nlabel)
{
  rtx x = pc_set (jump);
  int ochanges;
  int ok;

  ochanges = num_validated_changes ();
  if (x == NULL)
    return 0;
  ok = invert_exp_1 (SET_SRC (x), jump);
  gcc_assert (ok);

  if (num_validated_changes () == ochanges)
    return 0;

  /* redirect_jump_1 will fail of nlabel == olabel, and the current use is
     in Pmode, so checking this is not merely an optimization.  */
  return nlabel == JUMP_LABEL (jump) || redirect_jump_1 (jump, nlabel);
}

/* Invert the condition of the jump JUMP, and make it jump to label
   NLABEL instead of where it jumps now.  Return true if successful.  */

int
invert_jump (rtx jump, rtx nlabel, int delete_unused)
{
  rtx olabel = JUMP_LABEL (jump);

  if (invert_jump_1 (jump, nlabel) && apply_change_group ())
    {
      redirect_jump_2 (jump, olabel, nlabel, delete_unused, 1);
      return 1;
    }
  cancel_changes (0);
  return 0;
}


/* Like rtx_equal_p except that it considers two REGs as equal
   if they renumber to the same value and considers two commutative
   operations to be the same if the order of the operands has been
   reversed.  */

int
rtx_renumbered_equal_p (const_rtx x, const_rtx y)
{
  int i;
  const enum rtx_code code = GET_CODE (x);
  const char *fmt;

  if (x == y)
    return 1;

  if ((code == REG || (code == SUBREG && REG_P (SUBREG_REG (x))))
      && (REG_P (y) || (GET_CODE (y) == SUBREG
				  && REG_P (SUBREG_REG (y)))))
    {
      int reg_x = -1, reg_y = -1;
      int byte_x = 0, byte_y = 0;
      struct subreg_info info;

      if (GET_MODE (x) != GET_MODE (y))
	return 0;

      /* If we haven't done any renumbering, don't
	 make any assumptions.  */
      if (reg_renumber == 0)
	return rtx_equal_p (x, y);

      if (code == SUBREG)
	{
	  reg_x = REGNO (SUBREG_REG (x));
	  byte_x = SUBREG_BYTE (x);

	  if (reg_renumber[reg_x] >= 0)
	    {
	      subreg_get_info (reg_renumber[reg_x],
			       GET_MODE (SUBREG_REG (x)), byte_x,
			       GET_MODE (x), &info);
	      if (!info.representable_p)
		return 0;
	      reg_x = info.offset;
	      byte_x = 0;
	    }
	}
      else
	{
	  reg_x = REGNO (x);
	  if (reg_renumber[reg_x] >= 0)
	    reg_x = reg_renumber[reg_x];
	}

      if (GET_CODE (y) == SUBREG)
	{
	  reg_y = REGNO (SUBREG_REG (y));
	  byte_y = SUBREG_BYTE (y);

	  if (reg_renumber[reg_y] >= 0)
	    {
	      subreg_get_info (reg_renumber[reg_y],
			       GET_MODE (SUBREG_REG (y)), byte_y,
			       GET_MODE (y), &info);
	      if (!info.representable_p)
		return 0;
	      reg_y = info.offset;
	      byte_y = 0;
	    }
	}
      else
	{
	  reg_y = REGNO (y);
	  if (reg_renumber[reg_y] >= 0)
	    reg_y = reg_renumber[reg_y];
	}

      return reg_x >= 0 && reg_x == reg_y && byte_x == byte_y;
    }

  /* Now we have disposed of all the cases
     in which different rtx codes can match.  */
  if (code != GET_CODE (y))
    return 0;

  switch (code)
    {
    case PC:
    case CC0:
    case ADDR_VEC:
    case ADDR_DIFF_VEC:
    CASE_CONST_UNIQUE:
      return 0;

    case LABEL_REF:
      /* We can't assume nonlocal labels have their following insns yet.  */
      if (LABEL_REF_NONLOCAL_P (x) || LABEL_REF_NONLOCAL_P (y))
	return XEXP (x, 0) == XEXP (y, 0);

      /* Two label-refs are equivalent if they point at labels
	 in the same position in the instruction stream.  */
      return (next_real_insn (XEXP (x, 0))
	      == next_real_insn (XEXP (y, 0)));

    case SYMBOL_REF:
      return XSTR (x, 0) == XSTR (y, 0);

    case CODE_LABEL:
      /* If we didn't match EQ equality above, they aren't the same.  */
      return 0;

    default:
      break;
    }

  /* (MULT:SI x y) and (MULT:HI x y) are NOT equivalent.  */

  if (GET_MODE (x) != GET_MODE (y))
    return 0;

  /* MEMs referring to different address space are not equivalent.  */
  if (code == MEM && MEM_ADDR_SPACE (x) != MEM_ADDR_SPACE (y))
    return 0;

  /* For commutative operations, the RTX match if the operand match in any
     order.  Also handle the simple binary and unary cases without a loop.  */
  if (targetm.commutative_p (x, UNKNOWN))
    return ((rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0))
	     && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 1)))
	    || (rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 1))
		&& rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 0))));
  else if (NON_COMMUTATIVE_P (x))
    return (rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0))
	    && rtx_renumbered_equal_p (XEXP (x, 1), XEXP (y, 1)));
  else if (UNARY_P (x))
    return rtx_renumbered_equal_p (XEXP (x, 0), XEXP (y, 0));

  /* Compare the elements.  If any pair of corresponding elements
     fail to match, return 0 for the whole things.  */

  fmt = GET_RTX_FORMAT (code);
  for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
    {
      int j;
      switch (fmt[i])
	{
	case 'w':
	  if (XWINT (x, i) != XWINT (y, i))
	    return 0;
	  break;

	case 'i':
	  if (XINT (x, i) != XINT (y, i))
	    {
	      if (((code == ASM_OPERANDS && i == 6)
		   || (code == ASM_INPUT && i == 1)))
		break;
	      return 0;
	    }
	  break;

	case 't':
	  if (XTREE (x, i) != XTREE (y, i))
	    return 0;
	  break;

	case 's':
	  if (strcmp (XSTR (x, i), XSTR (y, i)))
	    return 0;
	  break;

	case 'e':
	  if (! rtx_renumbered_equal_p (XEXP (x, i), XEXP (y, i)))
	    return 0;
	  break;

	case 'u':
	  if (XEXP (x, i) != XEXP (y, i))
	    return 0;
	  /* Fall through.  */
	case '0':
	  break;

	case 'E':
	  if (XVECLEN (x, i) != XVECLEN (y, i))
	    return 0;
	  for (j = XVECLEN (x, i) - 1; j >= 0; j--)
	    if (!rtx_renumbered_equal_p (XVECEXP (x, i, j), XVECEXP (y, i, j)))
	      return 0;
	  break;

	default:
	  gcc_unreachable ();
	}
    }
  return 1;
}

/* If X is a hard register or equivalent to one or a subregister of one,
   return the hard register number.  If X is a pseudo register that was not
   assigned a hard register, return the pseudo register number.  Otherwise,
   return -1.  Any rtx is valid for X.  */

int
true_regnum (const_rtx x)
{
  if (REG_P (x))
    {
      if (REGNO (x) >= FIRST_PSEUDO_REGISTER
	  && (lra_in_progress || reg_renumber[REGNO (x)] >= 0))
	return reg_renumber[REGNO (x)];
      return REGNO (x);
    }
  if (GET_CODE (x) == SUBREG)
    {
      int base = true_regnum (SUBREG_REG (x));
      if (base >= 0
	  && base < FIRST_PSEUDO_REGISTER)
	{
	  struct subreg_info info;

	  subreg_get_info (lra_in_progress
			   ? (unsigned) base : REGNO (SUBREG_REG (x)),
			   GET_MODE (SUBREG_REG (x)),
			   SUBREG_BYTE (x), GET_MODE (x), &info);

	  if (info.representable_p)
	    return base + info.offset;
	}
    }
  return -1;
}

/* Return regno of the register REG and handle subregs too.  */
unsigned int
reg_or_subregno (const_rtx reg)
{
  if (GET_CODE (reg) == SUBREG)
    reg = SUBREG_REG (reg);
  gcc_assert (REG_P (reg));
  return REGNO (reg);
}