summaryrefslogtreecommitdiff
path: root/gcc/tree-ssa-forwprop.c
blob: 93f92f33a59a92b3ef71f944f9749bdbba4d12ef (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
1934
1935
1936
1937
1938
1939
1940
1941
1942
1943
1944
1945
1946
1947
1948
1949
1950
1951
1952
1953
1954
1955
1956
1957
1958
1959
1960
1961
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027
2028
2029
2030
2031
2032
2033
2034
2035
2036
2037
2038
2039
2040
2041
2042
2043
2044
2045
2046
2047
2048
2049
2050
2051
2052
2053
2054
2055
2056
2057
2058
2059
2060
2061
2062
2063
2064
2065
2066
2067
2068
2069
2070
2071
2072
2073
2074
2075
2076
2077
2078
2079
2080
2081
2082
2083
2084
2085
2086
2087
2088
2089
2090
2091
2092
2093
2094
2095
2096
2097
2098
2099
2100
2101
2102
2103
2104
2105
2106
2107
2108
2109
2110
2111
2112
2113
2114
2115
2116
2117
2118
2119
2120
2121
2122
2123
2124
2125
2126
2127
2128
2129
2130
2131
2132
2133
2134
2135
2136
2137
2138
2139
2140
2141
2142
2143
2144
2145
2146
2147
2148
2149
2150
2151
2152
2153
2154
2155
2156
2157
2158
2159
2160
2161
2162
2163
2164
2165
2166
2167
2168
2169
2170
2171
2172
2173
2174
2175
2176
2177
2178
2179
2180
2181
2182
2183
2184
2185
2186
2187
2188
2189
2190
2191
2192
2193
2194
2195
2196
2197
2198
2199
2200
2201
2202
2203
2204
2205
2206
2207
2208
2209
2210
2211
2212
2213
2214
2215
2216
2217
2218
2219
2220
2221
2222
2223
2224
2225
2226
2227
2228
2229
2230
2231
2232
2233
2234
2235
2236
2237
2238
2239
2240
2241
2242
2243
2244
2245
2246
2247
2248
2249
2250
2251
2252
2253
2254
2255
2256
2257
2258
2259
2260
2261
2262
2263
2264
2265
2266
2267
2268
2269
2270
2271
2272
2273
2274
2275
2276
2277
2278
2279
2280
2281
2282
2283
2284
2285
2286
2287
2288
2289
2290
2291
2292
2293
2294
2295
2296
2297
2298
2299
2300
2301
2302
2303
2304
2305
2306
2307
2308
2309
2310
2311
2312
2313
2314
2315
2316
2317
2318
2319
2320
2321
2322
2323
2324
2325
2326
2327
2328
2329
2330
2331
2332
2333
2334
2335
2336
2337
2338
2339
2340
2341
2342
2343
2344
2345
2346
2347
2348
2349
2350
2351
2352
2353
2354
2355
2356
2357
2358
2359
2360
2361
2362
2363
2364
2365
2366
2367
2368
2369
2370
2371
2372
2373
2374
2375
2376
2377
2378
2379
2380
2381
2382
2383
2384
2385
2386
2387
2388
2389
2390
2391
2392
2393
2394
2395
2396
2397
2398
2399
2400
2401
2402
2403
2404
2405
2406
2407
2408
2409
2410
2411
2412
2413
2414
2415
2416
2417
2418
2419
2420
2421
2422
2423
2424
2425
2426
2427
2428
2429
2430
2431
2432
2433
2434
2435
2436
2437
2438
2439
2440
2441
2442
2443
2444
2445
2446
2447
2448
2449
2450
2451
2452
2453
2454
2455
2456
2457
2458
2459
2460
2461
2462
2463
2464
2465
2466
2467
2468
2469
2470
2471
2472
2473
2474
2475
2476
2477
2478
2479
2480
2481
2482
2483
2484
2485
2486
2487
2488
2489
2490
2491
2492
2493
2494
2495
2496
2497
2498
2499
2500
2501
2502
2503
2504
2505
2506
2507
2508
2509
2510
/* Forward propagation of expressions for single use variables.
   Copyright (C) 2004-2015 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/>.  */

#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"
#include "hash-set.h"
#include "machmode.h"
#include "vec.h"
#include "double-int.h"
#include "input.h"
#include "alias.h"
#include "symtab.h"
#include "wide-int.h"
#include "inchash.h"
#include "tree.h"
#include "fold-const.h"
#include "stor-layout.h"
#include "tm_p.h"
#include "predict.h"
#include "hard-reg-set.h"
#include "function.h"
#include "dominance.h"
#include "cfg.h"
#include "basic-block.h"
#include "gimple-pretty-print.h"
#include "tree-ssa-alias.h"
#include "internal-fn.h"
#include "gimple-fold.h"
#include "tree-eh.h"
#include "gimple-expr.h"
#include "is-a.h"
#include "gimple.h"
#include "gimplify.h"
#include "gimple-iterator.h"
#include "gimplify-me.h"
#include "gimple-ssa.h"
#include "tree-cfg.h"
#include "tree-phinodes.h"
#include "ssa-iterators.h"
#include "stringpool.h"
#include "tree-ssanames.h"
#include "hashtab.h"
#include "rtl.h"
#include "flags.h"
#include "statistics.h"
#include "real.h"
#include "fixed-value.h"
#include "insn-config.h"
#include "expmed.h"
#include "dojump.h"
#include "explow.h"
#include "calls.h"
#include "emit-rtl.h"
#include "varasm.h"
#include "stmt.h"
#include "expr.h"
#include "tree-dfa.h"
#include "tree-pass.h"
#include "langhooks.h"
#include "diagnostic.h"
#include "cfgloop.h"
#include "insn-codes.h"
#include "optabs.h"
#include "tree-ssa-propagate.h"
#include "tree-ssa-dom.h"
#include "builtins.h"
#include "tree-cfgcleanup.h"
#include "tree-into-ssa.h"
#include "cfganal.h"

/* This pass propagates the RHS of assignment statements into use
   sites of the LHS of the assignment.  It's basically a specialized
   form of tree combination.   It is hoped all of this can disappear
   when we have a generalized tree combiner.

   One class of common cases we handle is forward propagating a single use
   variable into a COND_EXPR.

     bb0:
       x = a COND b;
       if (x) goto ... else goto ...

   Will be transformed into:

     bb0:
       if (a COND b) goto ... else goto ...

   Similarly for the tests (x == 0), (x != 0), (x == 1) and (x != 1).

   Or (assuming c1 and c2 are constants):

     bb0:
       x = a + c1;
       if (x EQ/NEQ c2) goto ... else goto ...

   Will be transformed into:

     bb0:
        if (a EQ/NEQ (c2 - c1)) goto ... else goto ...

   Similarly for x = a - c1.

   Or

     bb0:
       x = !a
       if (x) goto ... else goto ...

   Will be transformed into:

     bb0:
        if (a == 0) goto ... else goto ...

   Similarly for the tests (x == 0), (x != 0), (x == 1) and (x != 1).
   For these cases, we propagate A into all, possibly more than one,
   COND_EXPRs that use X.

   Or

     bb0:
       x = (typecast) a
       if (x) goto ... else goto ...

   Will be transformed into:

     bb0:
        if (a != 0) goto ... else goto ...

   (Assuming a is an integral type and x is a boolean or x is an
    integral and a is a boolean.)

   Similarly for the tests (x == 0), (x != 0), (x == 1) and (x != 1).
   For these cases, we propagate A into all, possibly more than one,
   COND_EXPRs that use X.

   In addition to eliminating the variable and the statement which assigns
   a value to the variable, we may be able to later thread the jump without
   adding insane complexity in the dominator optimizer.

   Also note these transformations can cascade.  We handle this by having
   a worklist of COND_EXPR statements to examine.  As we make a change to
   a statement, we put it back on the worklist to examine on the next
   iteration of the main loop.

   A second class of propagation opportunities arises for ADDR_EXPR
   nodes.

     ptr = &x->y->z;
     res = *ptr;

   Will get turned into

     res = x->y->z;

   Or
     ptr = (type1*)&type2var;
     res = *ptr

   Will get turned into (if type1 and type2 are the same size
   and neither have volatile on them):
     res = VIEW_CONVERT_EXPR<type1>(type2var)

   Or

     ptr = &x[0];
     ptr2 = ptr + <constant>;

   Will get turned into

     ptr2 = &x[constant/elementsize];

  Or

     ptr = &x[0];
     offset = index * element_size;
     offset_p = (pointer) offset;
     ptr2 = ptr + offset_p

  Will get turned into:

     ptr2 = &x[index];

  Or
    ssa = (int) decl
    res = ssa & 1

  Provided that decl has known alignment >= 2, will get turned into

    res = 0

  We also propagate casts into SWITCH_EXPR and COND_EXPR conditions to
  allow us to remove the cast and {NOT_EXPR,NEG_EXPR} into a subsequent
  {NOT_EXPR,NEG_EXPR}.

   This will (of course) be extended as other needs arise.  */

static bool forward_propagate_addr_expr (tree, tree, bool);

/* Set to true if we delete dead edges during the optimization.  */
static bool cfg_changed;

static tree rhs_to_tree (tree type, gimple stmt);

static bitmap to_purge;

/* Const-and-copy lattice.  */
static vec<tree> lattice;

/* Set the lattice entry for NAME to VAL.  */
static void
fwprop_set_lattice_val (tree name, tree val)
{
  if (TREE_CODE (name) == SSA_NAME)
    {
      if (SSA_NAME_VERSION (name) >= lattice.length ())
	{
	  lattice.reserve (num_ssa_names - lattice.length ());
	  lattice.quick_grow_cleared (num_ssa_names);
	}
      lattice[SSA_NAME_VERSION (name)] = val;
    }
}

/* Invalidate the lattice entry for NAME, done when releasing SSA names.  */
static void
fwprop_invalidate_lattice (tree name)
{
  if (name
      && TREE_CODE (name) == SSA_NAME
      && SSA_NAME_VERSION (name) < lattice.length ())
    lattice[SSA_NAME_VERSION (name)] = NULL_TREE;
}


/* Get the statement we can propagate from into NAME skipping
   trivial copies.  Returns the statement which defines the
   propagation source or NULL_TREE if there is no such one.
   If SINGLE_USE_ONLY is set considers only sources which have
   a single use chain up to NAME.  If SINGLE_USE_P is non-null,
   it is set to whether the chain to NAME is a single use chain
   or not.  SINGLE_USE_P is not written to if SINGLE_USE_ONLY is set.  */

static gimple
get_prop_source_stmt (tree name, bool single_use_only, bool *single_use_p)
{
  bool single_use = true;

  do {
    gimple def_stmt = SSA_NAME_DEF_STMT (name);

    if (!has_single_use (name))
      {
	single_use = false;
	if (single_use_only)
	  return NULL;
      }

    /* If name is defined by a PHI node or is the default def, bail out.  */
    if (!is_gimple_assign (def_stmt))
      return NULL;

    /* If def_stmt is a simple copy, continue looking.  */
    if (gimple_assign_rhs_code (def_stmt) == SSA_NAME)
      name = gimple_assign_rhs1 (def_stmt);
    else
      {
	if (!single_use_only && single_use_p)
	  *single_use_p = single_use;

	return def_stmt;
      }
  } while (1);
}

/* Checks if the destination ssa name in DEF_STMT can be used as
   propagation source.  Returns true if so, otherwise false.  */

static bool
can_propagate_from (gimple def_stmt)
{
  gcc_assert (is_gimple_assign (def_stmt));

  /* If the rhs has side-effects we cannot propagate from it.  */
  if (gimple_has_volatile_ops (def_stmt))
    return false;

  /* If the rhs is a load we cannot propagate from it.  */
  if (TREE_CODE_CLASS (gimple_assign_rhs_code (def_stmt)) == tcc_reference
      || TREE_CODE_CLASS (gimple_assign_rhs_code (def_stmt)) == tcc_declaration)
    return false;

  /* Constants can be always propagated.  */
  if (gimple_assign_single_p (def_stmt)
      && is_gimple_min_invariant (gimple_assign_rhs1 (def_stmt)))
    return true;

  /* We cannot propagate ssa names that occur in abnormal phi nodes.  */
  if (stmt_references_abnormal_ssa_name (def_stmt))
    return false;

  /* If the definition is a conversion of a pointer to a function type,
     then we can not apply optimizations as some targets require
     function pointers to be canonicalized and in this case this
     optimization could eliminate a necessary canonicalization.  */
  if (CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (def_stmt)))
    {
      tree rhs = gimple_assign_rhs1 (def_stmt);
      if (POINTER_TYPE_P (TREE_TYPE (rhs))
          && TREE_CODE (TREE_TYPE (TREE_TYPE (rhs))) == FUNCTION_TYPE)
        return false;
    }

  return true;
}

/* Remove a chain of dead statements starting at the definition of
   NAME.  The chain is linked via the first operand of the defining statements.
   If NAME was replaced in its only use then this function can be used
   to clean up dead stmts.  The function handles already released SSA
   names gracefully.
   Returns true if cleanup-cfg has to run.  */

static bool
remove_prop_source_from_use (tree name)
{
  gimple_stmt_iterator gsi;
  gimple stmt;
  bool cfg_changed = false;

  do {
    basic_block bb;

    if (SSA_NAME_IN_FREE_LIST (name)
	|| SSA_NAME_IS_DEFAULT_DEF (name)
	|| !has_zero_uses (name))
      return cfg_changed;

    stmt = SSA_NAME_DEF_STMT (name);
    if (gimple_code (stmt) == GIMPLE_PHI
	|| gimple_has_side_effects (stmt))
      return cfg_changed;

    bb = gimple_bb (stmt);
    gsi = gsi_for_stmt (stmt);
    unlink_stmt_vdef (stmt);
    if (gsi_remove (&gsi, true))
      bitmap_set_bit (to_purge, bb->index);
    fwprop_invalidate_lattice (gimple_get_lhs (stmt));
    release_defs (stmt);

    name = is_gimple_assign (stmt) ? gimple_assign_rhs1 (stmt) : NULL_TREE;
  } while (name && TREE_CODE (name) == SSA_NAME);

  return cfg_changed;
}

/* Return the rhs of a gassign *STMT in a form of a single tree,
   converted to type TYPE.

   This should disappear, but is needed so we can combine expressions and use
   the fold() interfaces. Long term, we need to develop folding and combine
   routines that deal with gimple exclusively . */

static tree
rhs_to_tree (tree type, gimple stmt)
{
  location_t loc = gimple_location (stmt);
  enum tree_code code = gimple_assign_rhs_code (stmt);
  if (get_gimple_rhs_class (code) == GIMPLE_TERNARY_RHS)
    return fold_build3_loc (loc, code, type, gimple_assign_rhs1 (stmt),
			    gimple_assign_rhs2 (stmt),
			    gimple_assign_rhs3 (stmt));
  else if (get_gimple_rhs_class (code) == GIMPLE_BINARY_RHS)
    return fold_build2_loc (loc, code, type, gimple_assign_rhs1 (stmt),
			gimple_assign_rhs2 (stmt));
  else if (get_gimple_rhs_class (code) == GIMPLE_UNARY_RHS)
    return build1 (code, type, gimple_assign_rhs1 (stmt));
  else if (get_gimple_rhs_class (code) == GIMPLE_SINGLE_RHS)
    return gimple_assign_rhs1 (stmt);
  else
    gcc_unreachable ();
}

/* Combine OP0 CODE OP1 in the context of a COND_EXPR.  Returns
   the folded result in a form suitable for COND_EXPR_COND or
   NULL_TREE, if there is no suitable simplified form.  If
   INVARIANT_ONLY is true only gimple_min_invariant results are
   considered simplified.  */

static tree
combine_cond_expr_cond (gimple stmt, enum tree_code code, tree type,
			tree op0, tree op1, bool invariant_only)
{
  tree t;

  gcc_assert (TREE_CODE_CLASS (code) == tcc_comparison);

  fold_defer_overflow_warnings ();
  t = fold_binary_loc (gimple_location (stmt), code, type, op0, op1);
  if (!t)
    {
      fold_undefer_overflow_warnings (false, NULL, 0);
      return NULL_TREE;
    }

  /* Require that we got a boolean type out if we put one in.  */
  gcc_assert (TREE_CODE (TREE_TYPE (t)) == TREE_CODE (type));

  /* Canonicalize the combined condition for use in a COND_EXPR.  */
  t = canonicalize_cond_expr_cond (t);

  /* Bail out if we required an invariant but didn't get one.  */
  if (!t || (invariant_only && !is_gimple_min_invariant (t)))
    {
      fold_undefer_overflow_warnings (false, NULL, 0);
      return NULL_TREE;
    }

  fold_undefer_overflow_warnings (!gimple_no_warning_p (stmt), stmt, 0);

  return t;
}

/* Combine the comparison OP0 CODE OP1 at LOC with the defining statements
   of its operand.  Return a new comparison tree or NULL_TREE if there
   were no simplifying combines.  */

static tree
forward_propagate_into_comparison_1 (gimple stmt,
				     enum tree_code code, tree type,
				     tree op0, tree op1)
{
  tree tmp = NULL_TREE;
  tree rhs0 = NULL_TREE, rhs1 = NULL_TREE;
  bool single_use0_p = false, single_use1_p = false;

  /* For comparisons use the first operand, that is likely to
     simplify comparisons against constants.  */
  if (TREE_CODE (op0) == SSA_NAME)
    {
      gimple def_stmt = get_prop_source_stmt (op0, false, &single_use0_p);
      if (def_stmt && can_propagate_from (def_stmt))
	{
	  enum tree_code def_code = gimple_assign_rhs_code (def_stmt);
	  bool invariant_only_p = !single_use0_p;

	  rhs0 = rhs_to_tree (TREE_TYPE (op1), def_stmt);

	  /* Always combine comparisons or conversions from booleans.  */
	  if (TREE_CODE (op1) == INTEGER_CST
	      && ((CONVERT_EXPR_CODE_P (def_code)
		   && TREE_CODE (TREE_TYPE (TREE_OPERAND (rhs0, 0)))
		      == BOOLEAN_TYPE)
		  || TREE_CODE_CLASS (def_code) == tcc_comparison))
	    invariant_only_p = false;

	  tmp = combine_cond_expr_cond (stmt, code, type,
					rhs0, op1, invariant_only_p);
	  if (tmp)
	    return tmp;
	}
    }

  /* If that wasn't successful, try the second operand.  */
  if (TREE_CODE (op1) == SSA_NAME)
    {
      gimple def_stmt = get_prop_source_stmt (op1, false, &single_use1_p);
      if (def_stmt && can_propagate_from (def_stmt))
	{
	  rhs1 = rhs_to_tree (TREE_TYPE (op0), def_stmt);
	  tmp = combine_cond_expr_cond (stmt, code, type,
					op0, rhs1, !single_use1_p);
	  if (tmp)
	    return tmp;
	}
    }

  /* If that wasn't successful either, try both operands.  */
  if (rhs0 != NULL_TREE
      && rhs1 != NULL_TREE)
    tmp = combine_cond_expr_cond (stmt, code, type,
				  rhs0, rhs1,
				  !(single_use0_p && single_use1_p));

  return tmp;
}

/* Propagate from the ssa name definition statements of the assignment
   from a comparison at *GSI into the conditional if that simplifies it.
   Returns 1 if the stmt was modified and 2 if the CFG needs cleanup,
   otherwise returns 0.  */

static int 
forward_propagate_into_comparison (gimple_stmt_iterator *gsi)
{
  gimple stmt = gsi_stmt (*gsi);
  tree tmp;
  bool cfg_changed = false;
  tree type = TREE_TYPE (gimple_assign_lhs (stmt));
  tree rhs1 = gimple_assign_rhs1 (stmt);
  tree rhs2 = gimple_assign_rhs2 (stmt);

  /* Combine the comparison with defining statements.  */
  tmp = forward_propagate_into_comparison_1 (stmt,
					     gimple_assign_rhs_code (stmt),
					     type, rhs1, rhs2);
  if (tmp && useless_type_conversion_p (type, TREE_TYPE (tmp)))
    {
      gimple_assign_set_rhs_from_tree (gsi, tmp);
      fold_stmt (gsi);
      update_stmt (gsi_stmt (*gsi));

      if (TREE_CODE (rhs1) == SSA_NAME)
	cfg_changed |= remove_prop_source_from_use (rhs1);
      if (TREE_CODE (rhs2) == SSA_NAME)
	cfg_changed |= remove_prop_source_from_use (rhs2);
      return cfg_changed ? 2 : 1;
    }

  return 0;
}

/* Propagate from the ssa name definition statements of COND_EXPR
   in GIMPLE_COND statement STMT into the conditional if that simplifies it.
   Returns zero if no statement was changed, one if there were
   changes and two if cfg_cleanup needs to run.

   This must be kept in sync with forward_propagate_into_cond.  */

static int
forward_propagate_into_gimple_cond (gcond *stmt)
{
  tree tmp;
  enum tree_code code = gimple_cond_code (stmt);
  bool cfg_changed = false;
  tree rhs1 = gimple_cond_lhs (stmt);
  tree rhs2 = gimple_cond_rhs (stmt);

  /* We can do tree combining on SSA_NAME and comparison expressions.  */
  if (TREE_CODE_CLASS (gimple_cond_code (stmt)) != tcc_comparison)
    return 0;

  tmp = forward_propagate_into_comparison_1 (stmt, code,
					     boolean_type_node,
					     rhs1, rhs2);
  if (tmp)
    {
      if (dump_file && tmp)
	{
	  fprintf (dump_file, "  Replaced '");
	  print_gimple_expr (dump_file, stmt, 0, 0);
	  fprintf (dump_file, "' with '");
	  print_generic_expr (dump_file, tmp, 0);
	  fprintf (dump_file, "'\n");
	}

      gimple_cond_set_condition_from_tree (stmt, unshare_expr (tmp));
      update_stmt (stmt);

      if (TREE_CODE (rhs1) == SSA_NAME)
	cfg_changed |= remove_prop_source_from_use (rhs1);
      if (TREE_CODE (rhs2) == SSA_NAME)
	cfg_changed |= remove_prop_source_from_use (rhs2);
      return (cfg_changed || is_gimple_min_invariant (tmp)) ? 2 : 1;
    }

  /* Canonicalize _Bool == 0 and _Bool != 1 to _Bool != 0 by swapping edges.  */
  if ((TREE_CODE (TREE_TYPE (rhs1)) == BOOLEAN_TYPE
       || (INTEGRAL_TYPE_P (TREE_TYPE (rhs1))
	   && TYPE_PRECISION (TREE_TYPE (rhs1)) == 1))
      && ((code == EQ_EXPR
	   && integer_zerop (rhs2))
	  || (code == NE_EXPR
	      && integer_onep (rhs2))))
    {
      basic_block bb = gimple_bb (stmt);
      gimple_cond_set_code (stmt, NE_EXPR);
      gimple_cond_set_rhs (stmt, build_zero_cst (TREE_TYPE (rhs1)));
      EDGE_SUCC (bb, 0)->flags ^= (EDGE_TRUE_VALUE|EDGE_FALSE_VALUE);
      EDGE_SUCC (bb, 1)->flags ^= (EDGE_TRUE_VALUE|EDGE_FALSE_VALUE);
      return 1;
    }

  return 0;
}


/* Propagate from the ssa name definition statements of COND_EXPR
   in the rhs of statement STMT into the conditional if that simplifies it.
   Returns true zero if the stmt was changed.  */

static bool
forward_propagate_into_cond (gimple_stmt_iterator *gsi_p)
{
  gimple stmt = gsi_stmt (*gsi_p);
  tree tmp = NULL_TREE;
  tree cond = gimple_assign_rhs1 (stmt);
  enum tree_code code = gimple_assign_rhs_code (stmt);

  /* We can do tree combining on SSA_NAME and comparison expressions.  */
  if (COMPARISON_CLASS_P (cond))
    tmp = forward_propagate_into_comparison_1 (stmt, TREE_CODE (cond),
					       TREE_TYPE (cond),
					       TREE_OPERAND (cond, 0),
					       TREE_OPERAND (cond, 1));
  else if (TREE_CODE (cond) == SSA_NAME)
    {
      enum tree_code def_code;
      tree name = cond;
      gimple def_stmt = get_prop_source_stmt (name, true, NULL);
      if (!def_stmt || !can_propagate_from (def_stmt))
	return 0;

      def_code = gimple_assign_rhs_code (def_stmt);
      if (TREE_CODE_CLASS (def_code) == tcc_comparison)
	tmp = fold_build2_loc (gimple_location (def_stmt),
			       def_code,
			       TREE_TYPE (cond),
			       gimple_assign_rhs1 (def_stmt),
			       gimple_assign_rhs2 (def_stmt));
    }

  if (tmp
      && is_gimple_condexpr (tmp))
    {
      if (dump_file && tmp)
	{
	  fprintf (dump_file, "  Replaced '");
	  print_generic_expr (dump_file, cond, 0);
	  fprintf (dump_file, "' with '");
	  print_generic_expr (dump_file, tmp, 0);
	  fprintf (dump_file, "'\n");
	}

      if ((code == VEC_COND_EXPR) ? integer_all_onesp (tmp)
				  : integer_onep (tmp))
	gimple_assign_set_rhs_from_tree (gsi_p, gimple_assign_rhs2 (stmt));
      else if (integer_zerop (tmp))
	gimple_assign_set_rhs_from_tree (gsi_p, gimple_assign_rhs3 (stmt));
      else
	gimple_assign_set_rhs1 (stmt, unshare_expr (tmp));
      stmt = gsi_stmt (*gsi_p);
      update_stmt (stmt);

      return true;
    }

  return 0;
}

/* We've just substituted an ADDR_EXPR into stmt.  Update all the
   relevant data structures to match.  */

static void
tidy_after_forward_propagate_addr (gimple stmt)
{
  /* We may have turned a trapping insn into a non-trapping insn.  */
  if (maybe_clean_or_replace_eh_stmt (stmt, stmt))
    bitmap_set_bit (to_purge, gimple_bb (stmt)->index);

  if (TREE_CODE (gimple_assign_rhs1 (stmt)) == ADDR_EXPR)
     recompute_tree_invariant_for_addr_expr (gimple_assign_rhs1 (stmt));
}

/* NAME is a SSA_NAME representing DEF_RHS which is of the form
   ADDR_EXPR <whatever>.

   Try to forward propagate the ADDR_EXPR into the use USE_STMT.
   Often this will allow for removal of an ADDR_EXPR and INDIRECT_REF
   node or for recovery of array indexing from pointer arithmetic.

   Return true if the propagation was successful (the propagation can
   be not totally successful, yet things may have been changed).  */

static bool
forward_propagate_addr_expr_1 (tree name, tree def_rhs,
			       gimple_stmt_iterator *use_stmt_gsi,
			       bool single_use_p)
{
  tree lhs, rhs, rhs2, array_ref;
  gimple use_stmt = gsi_stmt (*use_stmt_gsi);
  enum tree_code rhs_code;
  bool res = true;

  gcc_assert (TREE_CODE (def_rhs) == ADDR_EXPR);

  lhs = gimple_assign_lhs (use_stmt);
  rhs_code = gimple_assign_rhs_code (use_stmt);
  rhs = gimple_assign_rhs1 (use_stmt);

  /* Do not perform copy-propagation but recurse through copy chains.  */
  if (TREE_CODE (lhs) == SSA_NAME
      && rhs_code == SSA_NAME)
    return forward_propagate_addr_expr (lhs, def_rhs, single_use_p);

  /* The use statement could be a conversion.  Recurse to the uses of the
     lhs as copyprop does not copy through pointer to integer to pointer
     conversions and FRE does not catch all cases either.
     Treat the case of a single-use name and
     a conversion to def_rhs type separate, though.  */
  if (TREE_CODE (lhs) == SSA_NAME
      && CONVERT_EXPR_CODE_P (rhs_code))
    {
      /* If there is a point in a conversion chain where the types match
         so we can remove a conversion re-materialize the address here
	 and stop.  */
      if (single_use_p
	  && useless_type_conversion_p (TREE_TYPE (lhs), TREE_TYPE (def_rhs)))
	{
	  gimple_assign_set_rhs1 (use_stmt, unshare_expr (def_rhs));
	  gimple_assign_set_rhs_code (use_stmt, TREE_CODE (def_rhs));
	  return true;
	}

      /* Else recurse if the conversion preserves the address value.  */
      if ((INTEGRAL_TYPE_P (TREE_TYPE (lhs))
	   || POINTER_TYPE_P (TREE_TYPE (lhs)))
	  && (TYPE_PRECISION (TREE_TYPE (lhs))
	      >= TYPE_PRECISION (TREE_TYPE (def_rhs))))
	return forward_propagate_addr_expr (lhs, def_rhs, single_use_p);

      return false;
    }

  /* If this isn't a conversion chain from this on we only can propagate
     into compatible pointer contexts.  */
  if (!types_compatible_p (TREE_TYPE (name), TREE_TYPE (def_rhs)))
    return false;

  /* Propagate through constant pointer adjustments.  */
  if (TREE_CODE (lhs) == SSA_NAME
      && rhs_code == POINTER_PLUS_EXPR
      && rhs == name
      && TREE_CODE (gimple_assign_rhs2 (use_stmt)) == INTEGER_CST)
    {
      tree new_def_rhs;
      /* As we come here with non-invariant addresses in def_rhs we need
         to make sure we can build a valid constant offsetted address
	 for further propagation.  Simply rely on fold building that
	 and check after the fact.  */
      new_def_rhs = fold_build2 (MEM_REF, TREE_TYPE (TREE_TYPE (rhs)),
				 def_rhs,
				 fold_convert (ptr_type_node,
					       gimple_assign_rhs2 (use_stmt)));
      if (TREE_CODE (new_def_rhs) == MEM_REF
	  && !is_gimple_mem_ref_addr (TREE_OPERAND (new_def_rhs, 0)))
	return false;
      new_def_rhs = build_fold_addr_expr_with_type (new_def_rhs,
						    TREE_TYPE (rhs));

      /* Recurse.  If we could propagate into all uses of lhs do not
	 bother to replace into the current use but just pretend we did.  */
      if (TREE_CODE (new_def_rhs) == ADDR_EXPR
	  && forward_propagate_addr_expr (lhs, new_def_rhs, single_use_p))
	return true;

      if (useless_type_conversion_p (TREE_TYPE (lhs), TREE_TYPE (new_def_rhs)))
	gimple_assign_set_rhs_with_ops (use_stmt_gsi, TREE_CODE (new_def_rhs),
					new_def_rhs);
      else if (is_gimple_min_invariant (new_def_rhs))
	gimple_assign_set_rhs_with_ops (use_stmt_gsi, NOP_EXPR, new_def_rhs);
      else
	return false;
      gcc_assert (gsi_stmt (*use_stmt_gsi) == use_stmt);
      update_stmt (use_stmt);
      return true;
    }

  /* Now strip away any outer COMPONENT_REF/ARRAY_REF nodes from the LHS.
     ADDR_EXPR will not appear on the LHS.  */
  tree *lhsp = gimple_assign_lhs_ptr (use_stmt);
  while (handled_component_p (*lhsp))
    lhsp = &TREE_OPERAND (*lhsp, 0);
  lhs = *lhsp;

  /* Now see if the LHS node is a MEM_REF using NAME.  If so,
     propagate the ADDR_EXPR into the use of NAME and fold the result.  */
  if (TREE_CODE (lhs) == MEM_REF
      && TREE_OPERAND (lhs, 0) == name)
    {
      tree def_rhs_base;
      HOST_WIDE_INT def_rhs_offset;
      /* If the address is invariant we can always fold it.  */
      if ((def_rhs_base = get_addr_base_and_unit_offset (TREE_OPERAND (def_rhs, 0),
							 &def_rhs_offset)))
	{
	  offset_int off = mem_ref_offset (lhs);
	  tree new_ptr;
	  off += def_rhs_offset;
	  if (TREE_CODE (def_rhs_base) == MEM_REF)
	    {
	      off += mem_ref_offset (def_rhs_base);
	      new_ptr = TREE_OPERAND (def_rhs_base, 0);
	    }
	  else
	    new_ptr = build_fold_addr_expr (def_rhs_base);
	  TREE_OPERAND (lhs, 0) = new_ptr;
	  TREE_OPERAND (lhs, 1)
	    = wide_int_to_tree (TREE_TYPE (TREE_OPERAND (lhs, 1)), off);
	  tidy_after_forward_propagate_addr (use_stmt);
	  /* Continue propagating into the RHS if this was not the only use.  */
	  if (single_use_p)
	    return true;
	}
      /* If the LHS is a plain dereference and the value type is the same as
         that of the pointed-to type of the address we can put the
	 dereferenced address on the LHS preserving the original alias-type.  */
      else if (integer_zerop (TREE_OPERAND (lhs, 1))
	       && ((gimple_assign_lhs (use_stmt) == lhs
		    && useless_type_conversion_p
		         (TREE_TYPE (TREE_OPERAND (def_rhs, 0)),
		          TREE_TYPE (gimple_assign_rhs1 (use_stmt))))
		   || types_compatible_p (TREE_TYPE (lhs),
					  TREE_TYPE (TREE_OPERAND (def_rhs, 0))))
	       /* Don't forward anything into clobber stmts if it would result
		  in the lhs no longer being a MEM_REF.  */
	       && (!gimple_clobber_p (use_stmt)
		   || TREE_CODE (TREE_OPERAND (def_rhs, 0)) == MEM_REF))
	{
	  tree *def_rhs_basep = &TREE_OPERAND (def_rhs, 0);
	  tree new_offset, new_base, saved, new_lhs;
	  while (handled_component_p (*def_rhs_basep))
	    def_rhs_basep = &TREE_OPERAND (*def_rhs_basep, 0);
	  saved = *def_rhs_basep;
	  if (TREE_CODE (*def_rhs_basep) == MEM_REF)
	    {
	      new_base = TREE_OPERAND (*def_rhs_basep, 0);
	      new_offset = fold_convert (TREE_TYPE (TREE_OPERAND (lhs, 1)),
					 TREE_OPERAND (*def_rhs_basep, 1));
	    }
	  else
	    {
	      new_base = build_fold_addr_expr (*def_rhs_basep);
	      new_offset = TREE_OPERAND (lhs, 1);
	    }
	  *def_rhs_basep = build2 (MEM_REF, TREE_TYPE (*def_rhs_basep),
				   new_base, new_offset);
	  TREE_THIS_VOLATILE (*def_rhs_basep) = TREE_THIS_VOLATILE (lhs);
	  TREE_SIDE_EFFECTS (*def_rhs_basep) = TREE_SIDE_EFFECTS (lhs);
	  TREE_THIS_NOTRAP (*def_rhs_basep) = TREE_THIS_NOTRAP (lhs);
	  new_lhs = unshare_expr (TREE_OPERAND (def_rhs, 0));
	  *lhsp = new_lhs;
	  TREE_THIS_VOLATILE (new_lhs) = TREE_THIS_VOLATILE (lhs);
	  TREE_SIDE_EFFECTS (new_lhs) = TREE_SIDE_EFFECTS (lhs);
	  *def_rhs_basep = saved;
	  tidy_after_forward_propagate_addr (use_stmt);
	  /* Continue propagating into the RHS if this was not the
	     only use.  */
	  if (single_use_p)
	    return true;
	}
      else
	/* We can have a struct assignment dereferencing our name twice.
	   Note that we didn't propagate into the lhs to not falsely
	   claim we did when propagating into the rhs.  */
	res = false;
    }

  /* Strip away any outer COMPONENT_REF, ARRAY_REF or ADDR_EXPR
     nodes from the RHS.  */
  tree *rhsp = gimple_assign_rhs1_ptr (use_stmt);
  if (TREE_CODE (*rhsp) == ADDR_EXPR)
    rhsp = &TREE_OPERAND (*rhsp, 0);
  while (handled_component_p (*rhsp))
    rhsp = &TREE_OPERAND (*rhsp, 0);
  rhs = *rhsp;

  /* Now see if the RHS node is a MEM_REF using NAME.  If so,
     propagate the ADDR_EXPR into the use of NAME and fold the result.  */
  if (TREE_CODE (rhs) == MEM_REF
      && TREE_OPERAND (rhs, 0) == name)
    {
      tree def_rhs_base;
      HOST_WIDE_INT def_rhs_offset;
      if ((def_rhs_base = get_addr_base_and_unit_offset (TREE_OPERAND (def_rhs, 0),
							 &def_rhs_offset)))
	{
	  offset_int off = mem_ref_offset (rhs);
	  tree new_ptr;
	  off += def_rhs_offset;
	  if (TREE_CODE (def_rhs_base) == MEM_REF)
	    {
	      off += mem_ref_offset (def_rhs_base);
	      new_ptr = TREE_OPERAND (def_rhs_base, 0);
	    }
	  else
	    new_ptr = build_fold_addr_expr (def_rhs_base);
	  TREE_OPERAND (rhs, 0) = new_ptr;
	  TREE_OPERAND (rhs, 1)
	    = wide_int_to_tree (TREE_TYPE (TREE_OPERAND (rhs, 1)), off);
	  fold_stmt_inplace (use_stmt_gsi);
	  tidy_after_forward_propagate_addr (use_stmt);
	  return res;
	}
      /* If the RHS is a plain dereference and the value type is the same as
         that of the pointed-to type of the address we can put the
	 dereferenced address on the RHS preserving the original alias-type.  */
      else if (integer_zerop (TREE_OPERAND (rhs, 1))
	       && ((gimple_assign_rhs1 (use_stmt) == rhs
		    && useless_type_conversion_p
		         (TREE_TYPE (gimple_assign_lhs (use_stmt)),
		          TREE_TYPE (TREE_OPERAND (def_rhs, 0))))
		   || types_compatible_p (TREE_TYPE (rhs),
					  TREE_TYPE (TREE_OPERAND (def_rhs, 0)))))
	{
	  tree *def_rhs_basep = &TREE_OPERAND (def_rhs, 0);
	  tree new_offset, new_base, saved, new_rhs;
	  while (handled_component_p (*def_rhs_basep))
	    def_rhs_basep = &TREE_OPERAND (*def_rhs_basep, 0);
	  saved = *def_rhs_basep;
	  if (TREE_CODE (*def_rhs_basep) == MEM_REF)
	    {
	      new_base = TREE_OPERAND (*def_rhs_basep, 0);
	      new_offset = fold_convert (TREE_TYPE (TREE_OPERAND (rhs, 1)),
					 TREE_OPERAND (*def_rhs_basep, 1));
	    }
	  else
	    {
	      new_base = build_fold_addr_expr (*def_rhs_basep);
	      new_offset = TREE_OPERAND (rhs, 1);
	    }
	  *def_rhs_basep = build2 (MEM_REF, TREE_TYPE (*def_rhs_basep),
				   new_base, new_offset);
	  TREE_THIS_VOLATILE (*def_rhs_basep) = TREE_THIS_VOLATILE (rhs);
	  TREE_SIDE_EFFECTS (*def_rhs_basep) = TREE_SIDE_EFFECTS (rhs);
	  TREE_THIS_NOTRAP (*def_rhs_basep) = TREE_THIS_NOTRAP (rhs);
	  new_rhs = unshare_expr (TREE_OPERAND (def_rhs, 0));
	  *rhsp = new_rhs;
	  TREE_THIS_VOLATILE (new_rhs) = TREE_THIS_VOLATILE (rhs);
	  TREE_SIDE_EFFECTS (new_rhs) = TREE_SIDE_EFFECTS (rhs);
	  *def_rhs_basep = saved;
	  fold_stmt_inplace (use_stmt_gsi);
	  tidy_after_forward_propagate_addr (use_stmt);
	  return res;
	}
    }

  /* If the use of the ADDR_EXPR is not a POINTER_PLUS_EXPR, there
     is nothing to do. */
  if (gimple_assign_rhs_code (use_stmt) != POINTER_PLUS_EXPR
      || gimple_assign_rhs1 (use_stmt) != name)
    return false;

  /* The remaining cases are all for turning pointer arithmetic into
     array indexing.  They only apply when we have the address of
     element zero in an array.  If that is not the case then there
     is nothing to do.  */
  array_ref = TREE_OPERAND (def_rhs, 0);
  if ((TREE_CODE (array_ref) != ARRAY_REF
       || TREE_CODE (TREE_TYPE (TREE_OPERAND (array_ref, 0))) != ARRAY_TYPE
       || TREE_CODE (TREE_OPERAND (array_ref, 1)) != INTEGER_CST)
      && TREE_CODE (TREE_TYPE (array_ref)) != ARRAY_TYPE)
    return false;

  rhs2 = gimple_assign_rhs2 (use_stmt);
  /* Optimize &x[C1] p+ C2 to  &x p+ C3 with C3 = C1 * element_size + C2.  */
  if (TREE_CODE (rhs2) == INTEGER_CST)
    {
      tree new_rhs = build1_loc (gimple_location (use_stmt),
				 ADDR_EXPR, TREE_TYPE (def_rhs),
				 fold_build2 (MEM_REF,
					      TREE_TYPE (TREE_TYPE (def_rhs)),
					      unshare_expr (def_rhs),
					      fold_convert (ptr_type_node,
							    rhs2)));
      gimple_assign_set_rhs_from_tree (use_stmt_gsi, new_rhs);
      use_stmt = gsi_stmt (*use_stmt_gsi);
      update_stmt (use_stmt);
      tidy_after_forward_propagate_addr (use_stmt);
      return true;
    }

  return false;
}

/* STMT is a statement of the form SSA_NAME = ADDR_EXPR <whatever>.

   Try to forward propagate the ADDR_EXPR into all uses of the SSA_NAME.
   Often this will allow for removal of an ADDR_EXPR and INDIRECT_REF
   node or for recovery of array indexing from pointer arithmetic.

   PARENT_SINGLE_USE_P tells if, when in a recursive invocation, NAME was
   the single use in the previous invocation.  Pass true when calling
   this as toplevel.

   Returns true, if all uses have been propagated into.  */

static bool
forward_propagate_addr_expr (tree name, tree rhs, bool parent_single_use_p)
{
  imm_use_iterator iter;
  gimple use_stmt;
  bool all = true;
  bool single_use_p = parent_single_use_p && has_single_use (name);

  FOR_EACH_IMM_USE_STMT (use_stmt, iter, name)
    {
      bool result;
      tree use_rhs;

      /* If the use is not in a simple assignment statement, then
	 there is nothing we can do.  */
      if (!is_gimple_assign (use_stmt))
	{
	  if (!is_gimple_debug (use_stmt))
	    all = false;
	  continue;
	}

      gimple_stmt_iterator gsi = gsi_for_stmt (use_stmt);
      result = forward_propagate_addr_expr_1 (name, rhs, &gsi,
					      single_use_p);
      /* If the use has moved to a different statement adjust
	 the update machinery for the old statement too.  */
      if (use_stmt != gsi_stmt (gsi))
	{
	  update_stmt (use_stmt);
	  use_stmt = gsi_stmt (gsi);
	}
      update_stmt (use_stmt);
      all &= result;

      /* Remove intermediate now unused copy and conversion chains.  */
      use_rhs = gimple_assign_rhs1 (use_stmt);
      if (result
	  && TREE_CODE (gimple_assign_lhs (use_stmt)) == SSA_NAME
	  && TREE_CODE (use_rhs) == SSA_NAME
	  && has_zero_uses (gimple_assign_lhs (use_stmt)))
	{
	  gimple_stmt_iterator gsi = gsi_for_stmt (use_stmt);
	  fwprop_invalidate_lattice (gimple_get_lhs (use_stmt));
	  release_defs (use_stmt);
	  gsi_remove (&gsi, true);
	}
    }

  return all && has_zero_uses (name);
}


/* Helper function for simplify_gimple_switch.  Remove case labels that
   have values outside the range of the new type.  */

static void
simplify_gimple_switch_label_vec (gswitch *stmt, tree index_type)
{
  unsigned int branch_num = gimple_switch_num_labels (stmt);
  auto_vec<tree> labels (branch_num);
  unsigned int i, len;

  /* Collect the existing case labels in a VEC, and preprocess it as if
     we are gimplifying a GENERIC SWITCH_EXPR.  */
  for (i = 1; i < branch_num; i++)
    labels.quick_push (gimple_switch_label (stmt, i));
  preprocess_case_label_vec_for_gimple (labels, index_type, NULL);

  /* If any labels were removed, replace the existing case labels
     in the GIMPLE_SWITCH statement with the correct ones.
     Note that the type updates were done in-place on the case labels,
     so we only have to replace the case labels in the GIMPLE_SWITCH
     if the number of labels changed.  */
  len = labels.length ();
  if (len < branch_num - 1)
    {
      bitmap target_blocks;
      edge_iterator ei;
      edge e;

      /* Corner case: *all* case labels have been removed as being
	 out-of-range for INDEX_TYPE.  Push one label and let the
	 CFG cleanups deal with this further.  */
      if (len == 0)
	{
	  tree label, elt;

	  label = CASE_LABEL (gimple_switch_default_label (stmt));
	  elt = build_case_label (build_int_cst (index_type, 0), NULL, label);
	  labels.quick_push (elt);
	  len = 1;
	}

      for (i = 0; i < labels.length (); i++)
	gimple_switch_set_label (stmt, i + 1, labels[i]);
      for (i++ ; i < branch_num; i++)
	gimple_switch_set_label (stmt, i, NULL_TREE);
      gimple_switch_set_num_labels (stmt, len + 1);

      /* Cleanup any edges that are now dead.  */
      target_blocks = BITMAP_ALLOC (NULL);
      for (i = 0; i < gimple_switch_num_labels (stmt); i++)
	{
	  tree elt = gimple_switch_label (stmt, i);
	  basic_block target = label_to_block (CASE_LABEL (elt));
	  bitmap_set_bit (target_blocks, target->index);
	}
      for (ei = ei_start (gimple_bb (stmt)->succs); (e = ei_safe_edge (ei)); )
	{
	  if (! bitmap_bit_p (target_blocks, e->dest->index))
	    {
	      remove_edge (e);
	      cfg_changed = true;
	      free_dominance_info (CDI_DOMINATORS);
	    }
	  else
	    ei_next (&ei);
	} 
      BITMAP_FREE (target_blocks);
    }
}

/* STMT is a SWITCH_EXPR for which we attempt to find equivalent forms of
   the condition which we may be able to optimize better.  */

static bool
simplify_gimple_switch (gswitch *stmt)
{
  /* The optimization that we really care about is removing unnecessary
     casts.  That will let us do much better in propagating the inferred
     constant at the switch target.  */
  tree cond = gimple_switch_index (stmt);
  if (TREE_CODE (cond) == SSA_NAME)
    {
      gimple def_stmt = SSA_NAME_DEF_STMT (cond);
      if (gimple_assign_cast_p (def_stmt))
	{
	  tree def = gimple_assign_rhs1 (def_stmt);
	  if (TREE_CODE (def) != SSA_NAME)
	    return false;

	  /* If we have an extension or sign-change that preserves the
	     values we check against then we can copy the source value into
	     the switch.  */
	  tree ti = TREE_TYPE (def);
	  if (INTEGRAL_TYPE_P (ti)
	      && TYPE_PRECISION (ti) <= TYPE_PRECISION (TREE_TYPE (cond)))
	    {
	      size_t n = gimple_switch_num_labels (stmt);
	      tree min = NULL_TREE, max = NULL_TREE;
	      if (n > 1)
		{
		  min = CASE_LOW (gimple_switch_label (stmt, 1));
		  if (CASE_HIGH (gimple_switch_label (stmt, n - 1)))
		    max = CASE_HIGH (gimple_switch_label (stmt, n - 1));
		  else
		    max = CASE_LOW (gimple_switch_label (stmt, n - 1));
		}
	      if ((!min || int_fits_type_p (min, ti))
		  && (!max || int_fits_type_p (max, ti)))
		{
		  gimple_switch_set_index (stmt, def);
		  simplify_gimple_switch_label_vec (stmt, ti);
		  update_stmt (stmt);
		  return true;
		}
	    }
	}
    }

  return false;
}

/* For pointers p2 and p1 return p2 - p1 if the
   difference is known and constant, otherwise return NULL.  */

static tree
constant_pointer_difference (tree p1, tree p2)
{
  int i, j;
#define CPD_ITERATIONS 5
  tree exps[2][CPD_ITERATIONS];
  tree offs[2][CPD_ITERATIONS];
  int cnt[2];

  for (i = 0; i < 2; i++)
    {
      tree p = i ? p1 : p2;
      tree off = size_zero_node;
      gimple stmt;
      enum tree_code code;

      /* For each of p1 and p2 we need to iterate at least
	 twice, to handle ADDR_EXPR directly in p1/p2,
	 SSA_NAME with ADDR_EXPR or POINTER_PLUS_EXPR etc.
	 on definition's stmt RHS.  Iterate a few extra times.  */
      j = 0;
      do
	{
	  if (!POINTER_TYPE_P (TREE_TYPE (p)))
	    break;
	  if (TREE_CODE (p) == ADDR_EXPR)
	    {
	      tree q = TREE_OPERAND (p, 0);
	      HOST_WIDE_INT offset;
	      tree base = get_addr_base_and_unit_offset (q, &offset);
	      if (base)
		{
		  q = base;
		  if (offset)
		    off = size_binop (PLUS_EXPR, off, size_int (offset));
		}
	      if (TREE_CODE (q) == MEM_REF
		  && TREE_CODE (TREE_OPERAND (q, 0)) == SSA_NAME)
		{
		  p = TREE_OPERAND (q, 0);
		  off = size_binop (PLUS_EXPR, off,
				    wide_int_to_tree (sizetype,
						      mem_ref_offset (q)));
		}
	      else
		{
		  exps[i][j] = q;
		  offs[i][j++] = off;
		  break;
		}
	    }
	  if (TREE_CODE (p) != SSA_NAME)
	    break;
	  exps[i][j] = p;
	  offs[i][j++] = off;
	  if (j == CPD_ITERATIONS)
	    break;
	  stmt = SSA_NAME_DEF_STMT (p);
	  if (!is_gimple_assign (stmt) || gimple_assign_lhs (stmt) != p)
	    break;
	  code = gimple_assign_rhs_code (stmt);
	  if (code == POINTER_PLUS_EXPR)
	    {
	      if (TREE_CODE (gimple_assign_rhs2 (stmt)) != INTEGER_CST)
		break;
	      off = size_binop (PLUS_EXPR, off, gimple_assign_rhs2 (stmt));
	      p = gimple_assign_rhs1 (stmt);
	    }
	  else if (code == ADDR_EXPR || CONVERT_EXPR_CODE_P (code))
	    p = gimple_assign_rhs1 (stmt);
	  else
	    break;
	}
      while (1);
      cnt[i] = j;
    }

  for (i = 0; i < cnt[0]; i++)
    for (j = 0; j < cnt[1]; j++)
      if (exps[0][i] == exps[1][j])
	return size_binop (MINUS_EXPR, offs[0][i], offs[1][j]);

  return NULL_TREE;
}

/* *GSI_P is a GIMPLE_CALL to a builtin function.
   Optimize
   memcpy (p, "abcd", 4);
   memset (p + 4, ' ', 3);
   into
   memcpy (p, "abcd   ", 7);
   call if the latter can be stored by pieces during expansion.  */

static bool
simplify_builtin_call (gimple_stmt_iterator *gsi_p, tree callee2)
{
  gimple stmt1, stmt2 = gsi_stmt (*gsi_p);
  tree vuse = gimple_vuse (stmt2);
  if (vuse == NULL)
    return false;
  stmt1 = SSA_NAME_DEF_STMT (vuse);

  switch (DECL_FUNCTION_CODE (callee2))
    {
    case BUILT_IN_MEMSET:
      if (gimple_call_num_args (stmt2) != 3
	  || gimple_call_lhs (stmt2)
	  || CHAR_BIT != 8
	  || BITS_PER_UNIT != 8)
	break;
      else
	{
	  tree callee1;
	  tree ptr1, src1, str1, off1, len1, lhs1;
	  tree ptr2 = gimple_call_arg (stmt2, 0);
	  tree val2 = gimple_call_arg (stmt2, 1);
	  tree len2 = gimple_call_arg (stmt2, 2);
	  tree diff, vdef, new_str_cst;
	  gimple use_stmt;
	  unsigned int ptr1_align;
	  unsigned HOST_WIDE_INT src_len;
	  char *src_buf;
	  use_operand_p use_p;

	  if (!tree_fits_shwi_p (val2)
	      || !tree_fits_uhwi_p (len2)
	      || compare_tree_int (len2, 1024) == 1)
	    break;
	  if (is_gimple_call (stmt1))
	    {
	      /* If first stmt is a call, it needs to be memcpy
		 or mempcpy, with string literal as second argument and
		 constant length.  */
	      callee1 = gimple_call_fndecl (stmt1);
	      if (callee1 == NULL_TREE
		  || DECL_BUILT_IN_CLASS (callee1) != BUILT_IN_NORMAL
		  || gimple_call_num_args (stmt1) != 3)
		break;
	      if (DECL_FUNCTION_CODE (callee1) != BUILT_IN_MEMCPY
		  && DECL_FUNCTION_CODE (callee1) != BUILT_IN_MEMPCPY)
		break;
	      ptr1 = gimple_call_arg (stmt1, 0);
	      src1 = gimple_call_arg (stmt1, 1);
	      len1 = gimple_call_arg (stmt1, 2);
	      lhs1 = gimple_call_lhs (stmt1);
	      if (!tree_fits_uhwi_p (len1))
		break;
	      str1 = string_constant (src1, &off1);
	      if (str1 == NULL_TREE)
		break;
	      if (!tree_fits_uhwi_p (off1)
		  || compare_tree_int (off1, TREE_STRING_LENGTH (str1) - 1) > 0
		  || compare_tree_int (len1, TREE_STRING_LENGTH (str1)
					     - tree_to_uhwi (off1)) > 0
		  || TREE_CODE (TREE_TYPE (str1)) != ARRAY_TYPE
		  || TYPE_MODE (TREE_TYPE (TREE_TYPE (str1)))
		     != TYPE_MODE (char_type_node))
		break;
	    }
	  else if (gimple_assign_single_p (stmt1))
	    {
	      /* Otherwise look for length 1 memcpy optimized into
		 assignment.  */
    	      ptr1 = gimple_assign_lhs (stmt1);
	      src1 = gimple_assign_rhs1 (stmt1);
	      if (TREE_CODE (ptr1) != MEM_REF
		  || TYPE_MODE (TREE_TYPE (ptr1)) != TYPE_MODE (char_type_node)
		  || !tree_fits_shwi_p (src1))
		break;
	      ptr1 = build_fold_addr_expr (ptr1);
	      callee1 = NULL_TREE;
	      len1 = size_one_node;
	      lhs1 = NULL_TREE;
	      off1 = size_zero_node;
	      str1 = NULL_TREE;
	    }
	  else
	    break;

	  diff = constant_pointer_difference (ptr1, ptr2);
	  if (diff == NULL && lhs1 != NULL)
	    {
	      diff = constant_pointer_difference (lhs1, ptr2);
	      if (DECL_FUNCTION_CODE (callee1) == BUILT_IN_MEMPCPY
		  && diff != NULL)
		diff = size_binop (PLUS_EXPR, diff,
				   fold_convert (sizetype, len1));
	    }
	  /* If the difference between the second and first destination pointer
	     is not constant, or is bigger than memcpy length, bail out.  */
	  if (diff == NULL
	      || !tree_fits_uhwi_p (diff)
	      || tree_int_cst_lt (len1, diff)
	      || compare_tree_int (diff, 1024) == 1)
	    break;

	  /* Use maximum of difference plus memset length and memcpy length
	     as the new memcpy length, if it is too big, bail out.  */
	  src_len = tree_to_uhwi (diff);
	  src_len += tree_to_uhwi (len2);
	  if (src_len < tree_to_uhwi (len1))
	    src_len = tree_to_uhwi (len1);
	  if (src_len > 1024)
	    break;

	  /* If mempcpy value is used elsewhere, bail out, as mempcpy
	     with bigger length will return different result.  */
	  if (lhs1 != NULL_TREE
	      && DECL_FUNCTION_CODE (callee1) == BUILT_IN_MEMPCPY
	      && (TREE_CODE (lhs1) != SSA_NAME
		  || !single_imm_use (lhs1, &use_p, &use_stmt)
		  || use_stmt != stmt2))
	    break;

	  /* If anything reads memory in between memcpy and memset
	     call, the modified memcpy call might change it.  */
	  vdef = gimple_vdef (stmt1);
	  if (vdef != NULL
	      && (!single_imm_use (vdef, &use_p, &use_stmt)
		  || use_stmt != stmt2))
	    break;

	  ptr1_align = get_pointer_alignment (ptr1);
	  /* Construct the new source string literal.  */
	  src_buf = XALLOCAVEC (char, src_len + 1);
	  if (callee1)
	    memcpy (src_buf,
		    TREE_STRING_POINTER (str1) + tree_to_uhwi (off1),
		    tree_to_uhwi (len1));
	  else
	    src_buf[0] = tree_to_shwi (src1);
	  memset (src_buf + tree_to_uhwi (diff),
		  tree_to_shwi (val2), tree_to_uhwi (len2));
	  src_buf[src_len] = '\0';
	  /* Neither builtin_strncpy_read_str nor builtin_memcpy_read_str
	     handle embedded '\0's.  */
	  if (strlen (src_buf) != src_len)
	    break;
	  rtl_profile_for_bb (gimple_bb (stmt2));
	  /* If the new memcpy wouldn't be emitted by storing the literal
	     by pieces, this optimization might enlarge .rodata too much,
	     as commonly used string literals couldn't be shared any
	     longer.  */
	  if (!can_store_by_pieces (src_len,
				    builtin_strncpy_read_str,
				    src_buf, ptr1_align, false))
	    break;

	  new_str_cst = build_string_literal (src_len, src_buf);
	  if (callee1)
	    {
	      /* If STMT1 is a mem{,p}cpy call, adjust it and remove
		 memset call.  */
	      if (lhs1 && DECL_FUNCTION_CODE (callee1) == BUILT_IN_MEMPCPY)
		gimple_call_set_lhs (stmt1, NULL_TREE);
	      gimple_call_set_arg (stmt1, 1, new_str_cst);
	      gimple_call_set_arg (stmt1, 2,
				   build_int_cst (TREE_TYPE (len1), src_len));
	      update_stmt (stmt1);
	      unlink_stmt_vdef (stmt2);
	      gsi_remove (gsi_p, true);
	      fwprop_invalidate_lattice (gimple_get_lhs (stmt2));
	      release_defs (stmt2);
	      if (lhs1 && DECL_FUNCTION_CODE (callee1) == BUILT_IN_MEMPCPY)
		{
		  fwprop_invalidate_lattice (lhs1);
		  release_ssa_name (lhs1);
		}
	      return true;
	    }
	  else
	    {
	      /* Otherwise, if STMT1 is length 1 memcpy optimized into
		 assignment, remove STMT1 and change memset call into
		 memcpy call.  */
	      gimple_stmt_iterator gsi = gsi_for_stmt (stmt1);

	      if (!is_gimple_val (ptr1))
		ptr1 = force_gimple_operand_gsi (gsi_p, ptr1, true, NULL_TREE,
						 true, GSI_SAME_STMT);
	      gimple_call_set_fndecl (stmt2,
				      builtin_decl_explicit (BUILT_IN_MEMCPY));
	      gimple_call_set_arg (stmt2, 0, ptr1);
	      gimple_call_set_arg (stmt2, 1, new_str_cst);
	      gimple_call_set_arg (stmt2, 2,
				   build_int_cst (TREE_TYPE (len2), src_len));
	      unlink_stmt_vdef (stmt1);
	      gsi_remove (&gsi, true);
	      fwprop_invalidate_lattice (gimple_get_lhs (stmt1));
	      release_defs (stmt1);
	      update_stmt (stmt2);
	      return false;
	    }
	}
      break;
    default:
      break;
    }
  return false;
}

/* Given a ssa_name in NAME see if it was defined by an assignment and
   set CODE to be the code and ARG1 to the first operand on the rhs and ARG2
   to the second operand on the rhs. */

static inline void
defcodefor_name (tree name, enum tree_code *code, tree *arg1, tree *arg2)
{
  gimple def;
  enum tree_code code1;
  tree arg11;
  tree arg21;
  tree arg31;
  enum gimple_rhs_class grhs_class;

  code1 = TREE_CODE (name);
  arg11 = name;
  arg21 = NULL_TREE;
  grhs_class = get_gimple_rhs_class (code1);

  if (code1 == SSA_NAME)
    {
      def = SSA_NAME_DEF_STMT (name);
      
      if (def && is_gimple_assign (def)
	  && can_propagate_from (def))
	{
	  code1 = gimple_assign_rhs_code (def);
	  arg11 = gimple_assign_rhs1 (def);
          arg21 = gimple_assign_rhs2 (def);
          arg31 = gimple_assign_rhs2 (def);
	}
    }
  else if (grhs_class == GIMPLE_TERNARY_RHS
	   || GIMPLE_BINARY_RHS
	   || GIMPLE_UNARY_RHS
	   || GIMPLE_SINGLE_RHS)
    extract_ops_from_tree_1 (name, &code1, &arg11, &arg21, &arg31);

  *code = code1;
  *arg1 = arg11;
  if (arg2)
    *arg2 = arg21;
  /* Ignore arg3 currently. */
}


/* Recognize rotation patterns.  Return true if a transformation
   applied, otherwise return false.

   We are looking for X with unsigned type T with bitsize B, OP being
   +, | or ^, some type T2 wider than T and
   (X << CNT1) OP (X >> CNT2)				iff CNT1 + CNT2 == B
   ((T) ((T2) X << CNT1)) OP ((T) ((T2) X >> CNT2))	iff CNT1 + CNT2 == B
   (X << Y) OP (X >> (B - Y))
   (X << (int) Y) OP (X >> (int) (B - Y))
   ((T) ((T2) X << Y)) OP ((T) ((T2) X >> (B - Y)))
   ((T) ((T2) X << (int) Y)) OP ((T) ((T2) X >> (int) (B - Y)))
   (X << Y) | (X >> ((-Y) & (B - 1)))
   (X << (int) Y) | (X >> (int) ((-Y) & (B - 1)))
   ((T) ((T2) X << Y)) | ((T) ((T2) X >> ((-Y) & (B - 1))))
   ((T) ((T2) X << (int) Y)) | ((T) ((T2) X >> (int) ((-Y) & (B - 1))))

   and transform these into:
   X r<< CNT1
   X r<< Y

   Note, in the patterns with T2 type, the type of OP operands
   might be even a signed type, but should have precision B.  */

static bool
simplify_rotate (gimple_stmt_iterator *gsi)
{
  gimple stmt = gsi_stmt (*gsi);
  tree arg[2], rtype, rotcnt = NULL_TREE;
  tree def_arg1[2], def_arg2[2];
  enum tree_code def_code[2];
  tree lhs;
  int i;
  bool swapped_p = false;
  gimple g;

  arg[0] = gimple_assign_rhs1 (stmt);
  arg[1] = gimple_assign_rhs2 (stmt);
  rtype = TREE_TYPE (arg[0]);

  /* Only create rotates in complete modes.  Other cases are not
     expanded properly.  */
  if (!INTEGRAL_TYPE_P (rtype)
      || TYPE_PRECISION (rtype) != GET_MODE_PRECISION (TYPE_MODE (rtype)))
    return false;

  for (i = 0; i < 2; i++)
    defcodefor_name (arg[i], &def_code[i], &def_arg1[i], &def_arg2[i]);

  /* Look through narrowing conversions.  */
  if (CONVERT_EXPR_CODE_P (def_code[0])
      && CONVERT_EXPR_CODE_P (def_code[1])
      && INTEGRAL_TYPE_P (TREE_TYPE (def_arg1[0]))
      && INTEGRAL_TYPE_P (TREE_TYPE (def_arg1[1]))
      && TYPE_PRECISION (TREE_TYPE (def_arg1[0]))
	 == TYPE_PRECISION (TREE_TYPE (def_arg1[1]))
      && TYPE_PRECISION (TREE_TYPE (def_arg1[0])) > TYPE_PRECISION (rtype)
      && has_single_use (arg[0])
      && has_single_use (arg[1]))
    {
      for (i = 0; i < 2; i++)
	{
	  arg[i] = def_arg1[i];
	  defcodefor_name (arg[i], &def_code[i], &def_arg1[i], &def_arg2[i]);
	}
    }

  /* One operand has to be LSHIFT_EXPR and one RSHIFT_EXPR.  */
  for (i = 0; i < 2; i++)
    if (def_code[i] != LSHIFT_EXPR && def_code[i] != RSHIFT_EXPR)
      return false;
    else if (!has_single_use (arg[i]))
      return false;
  if (def_code[0] == def_code[1])
    return false;

  /* If we've looked through narrowing conversions before, look through
     widening conversions from unsigned type with the same precision
     as rtype here.  */
  if (TYPE_PRECISION (TREE_TYPE (def_arg1[0])) != TYPE_PRECISION (rtype))
    for (i = 0; i < 2; i++)
      {
	tree tem;
	enum tree_code code;
	defcodefor_name (def_arg1[i], &code, &tem, NULL);
	if (!CONVERT_EXPR_CODE_P (code)
	    || !INTEGRAL_TYPE_P (TREE_TYPE (tem))
	    || TYPE_PRECISION (TREE_TYPE (tem)) != TYPE_PRECISION (rtype))
	  return false;
	def_arg1[i] = tem;
      }
  /* Both shifts have to use the same first operand.  */
  if (TREE_CODE (def_arg1[0]) != SSA_NAME || def_arg1[0] != def_arg1[1])
    return false;
  if (!TYPE_UNSIGNED (TREE_TYPE (def_arg1[0])))
    return false;

  /* CNT1 + CNT2 == B case above.  */
  if (tree_fits_uhwi_p (def_arg2[0])
      && tree_fits_uhwi_p (def_arg2[1])
      && tree_to_uhwi (def_arg2[0])
	 + tree_to_uhwi (def_arg2[1]) == TYPE_PRECISION (rtype))
    rotcnt = def_arg2[0];
  else if (TREE_CODE (def_arg2[0]) != SSA_NAME
	   || TREE_CODE (def_arg2[1]) != SSA_NAME)
    return false;
  else
    {
      tree cdef_arg1[2], cdef_arg2[2], def_arg2_alt[2];
      enum tree_code cdef_code[2];
      /* Look through conversion of the shift count argument.
	 The C/C++ FE cast any shift count argument to integer_type_node.
	 The only problem might be if the shift count type maximum value
	 is equal or smaller than number of bits in rtype.  */
      for (i = 0; i < 2; i++)
	{
	  def_arg2_alt[i] = def_arg2[i];
	  defcodefor_name (def_arg2[i], &cdef_code[i],
			   &cdef_arg1[i], &cdef_arg2[i]);
	  if (CONVERT_EXPR_CODE_P (cdef_code[i])
	      && INTEGRAL_TYPE_P (TREE_TYPE (cdef_arg1[i]))
	      && TYPE_PRECISION (TREE_TYPE (cdef_arg1[i]))
		 > floor_log2 (TYPE_PRECISION (rtype))
	      && TYPE_PRECISION (TREE_TYPE (cdef_arg1[i]))
		 == GET_MODE_PRECISION (TYPE_MODE (TREE_TYPE (cdef_arg1[i]))))
	    {
	      def_arg2_alt[i] = cdef_arg1[i];
	      defcodefor_name (def_arg2_alt[i], &cdef_code[i],
			       &cdef_arg1[i], &cdef_arg2[i]);
	    }
	}
      for (i = 0; i < 2; i++)
	/* Check for one shift count being Y and the other B - Y,
	   with optional casts.  */
	if (cdef_code[i] == MINUS_EXPR
	    && tree_fits_shwi_p (cdef_arg1[i])
	    && tree_to_shwi (cdef_arg1[i]) == TYPE_PRECISION (rtype)
	    && TREE_CODE (cdef_arg2[i]) == SSA_NAME)
	  {
	    tree tem;
	    enum tree_code code;

	    if (cdef_arg2[i] == def_arg2[1 - i]
		|| cdef_arg2[i] == def_arg2_alt[1 - i])
	      {
		rotcnt = cdef_arg2[i];
		break;
	      }
	    defcodefor_name (cdef_arg2[i], &code, &tem, NULL);
	    if (CONVERT_EXPR_CODE_P (code)
		&& INTEGRAL_TYPE_P (TREE_TYPE (tem))
		&& TYPE_PRECISION (TREE_TYPE (tem))
		 > floor_log2 (TYPE_PRECISION (rtype))
		&& TYPE_PRECISION (TREE_TYPE (tem))
		 == GET_MODE_PRECISION (TYPE_MODE (TREE_TYPE (tem)))
		&& (tem == def_arg2[1 - i]
		    || tem == def_arg2_alt[1 - i]))
	      {
		rotcnt = tem;
		break;
	      }
	  }
	/* The above sequence isn't safe for Y being 0,
	   because then one of the shifts triggers undefined behavior.
	   This alternative is safe even for rotation count of 0.
	   One shift count is Y and the other (-Y) & (B - 1).  */
	else if (cdef_code[i] == BIT_AND_EXPR
		 && tree_fits_shwi_p (cdef_arg2[i])
		 && tree_to_shwi (cdef_arg2[i])
		    == TYPE_PRECISION (rtype) - 1
		 && TREE_CODE (cdef_arg1[i]) == SSA_NAME
		 && gimple_assign_rhs_code (stmt) == BIT_IOR_EXPR)
	  {
	    tree tem;
	    enum tree_code code;

	    defcodefor_name (cdef_arg1[i], &code, &tem, NULL);
	    if (CONVERT_EXPR_CODE_P (code)
		&& INTEGRAL_TYPE_P (TREE_TYPE (tem))
		&& TYPE_PRECISION (TREE_TYPE (tem))
		 > floor_log2 (TYPE_PRECISION (rtype))
		&& TYPE_PRECISION (TREE_TYPE (tem))
		 == GET_MODE_PRECISION (TYPE_MODE (TREE_TYPE (tem))))
	      defcodefor_name (tem, &code, &tem, NULL);

	    if (code == NEGATE_EXPR)
	      {
		if (tem == def_arg2[1 - i] || tem == def_arg2_alt[1 - i])
		  {
		    rotcnt = tem;
		    break;
		  }
		defcodefor_name (tem, &code, &tem, NULL);
		if (CONVERT_EXPR_CODE_P (code)
		    && INTEGRAL_TYPE_P (TREE_TYPE (tem))
		    && TYPE_PRECISION (TREE_TYPE (tem))
		       > floor_log2 (TYPE_PRECISION (rtype))
		    && TYPE_PRECISION (TREE_TYPE (tem))
		       == GET_MODE_PRECISION (TYPE_MODE (TREE_TYPE (tem)))
		    && (tem == def_arg2[1 - i]
			|| tem == def_arg2_alt[1 - i]))
		  {
		    rotcnt = tem;
		    break;
		  }
	      }
	  }
      if (rotcnt == NULL_TREE)
	return false;
      swapped_p = i != 1;
    }

  if (!useless_type_conversion_p (TREE_TYPE (def_arg2[0]),
				  TREE_TYPE (rotcnt)))
    {
      g = gimple_build_assign (make_ssa_name (TREE_TYPE (def_arg2[0])),
			       NOP_EXPR, rotcnt);
      gsi_insert_before (gsi, g, GSI_SAME_STMT);
      rotcnt = gimple_assign_lhs (g);
    }
  lhs = gimple_assign_lhs (stmt);
  if (!useless_type_conversion_p (rtype, TREE_TYPE (def_arg1[0])))
    lhs = make_ssa_name (TREE_TYPE (def_arg1[0]));
  g = gimple_build_assign (lhs,
			   ((def_code[0] == LSHIFT_EXPR) ^ swapped_p)
			   ? LROTATE_EXPR : RROTATE_EXPR, def_arg1[0], rotcnt);
  if (!useless_type_conversion_p (rtype, TREE_TYPE (def_arg1[0])))
    {
      gsi_insert_before (gsi, g, GSI_SAME_STMT);
      g = gimple_build_assign (gimple_assign_lhs (stmt), NOP_EXPR, lhs);
    }
  gsi_replace (gsi, g, false);
  return true;
}

/* Combine an element access with a shuffle.  Returns true if there were
   any changes made, else it returns false.  */
 
static bool
simplify_bitfield_ref (gimple_stmt_iterator *gsi)
{
  gimple stmt = gsi_stmt (*gsi);
  gimple def_stmt;
  tree op, op0, op1, op2;
  tree elem_type;
  unsigned idx, n, size;
  enum tree_code code;

  op = gimple_assign_rhs1 (stmt);
  gcc_checking_assert (TREE_CODE (op) == BIT_FIELD_REF);

  op0 = TREE_OPERAND (op, 0);
  if (TREE_CODE (op0) != SSA_NAME
      || TREE_CODE (TREE_TYPE (op0)) != VECTOR_TYPE)
    return false;

  def_stmt = get_prop_source_stmt (op0, false, NULL);
  if (!def_stmt || !can_propagate_from (def_stmt))
    return false;

  op1 = TREE_OPERAND (op, 1);
  op2 = TREE_OPERAND (op, 2);
  code = gimple_assign_rhs_code (def_stmt);

  if (code == CONSTRUCTOR)
    {
      tree tem = fold_ternary (BIT_FIELD_REF, TREE_TYPE (op),
			       gimple_assign_rhs1 (def_stmt), op1, op2);
      if (!tem || !valid_gimple_rhs_p (tem))
	return false;
      gimple_assign_set_rhs_from_tree (gsi, tem);
      update_stmt (gsi_stmt (*gsi));
      return true;
    }

  elem_type = TREE_TYPE (TREE_TYPE (op0));
  if (TREE_TYPE (op) != elem_type)
    return false;

  size = TREE_INT_CST_LOW (TYPE_SIZE (elem_type));
  n = TREE_INT_CST_LOW (op1) / size;
  if (n != 1)
    return false;
  idx = TREE_INT_CST_LOW (op2) / size;

  if (code == VEC_PERM_EXPR)
    {
      tree p, m, index, tem;
      unsigned nelts;
      m = gimple_assign_rhs3 (def_stmt);
      if (TREE_CODE (m) != VECTOR_CST)
	return false;
      nelts = VECTOR_CST_NELTS (m);
      idx = TREE_INT_CST_LOW (VECTOR_CST_ELT (m, idx));
      idx %= 2 * nelts;
      if (idx < nelts)
	{
	  p = gimple_assign_rhs1 (def_stmt);
	}
      else
	{
	  p = gimple_assign_rhs2 (def_stmt);
	  idx -= nelts;
	}
      index = build_int_cst (TREE_TYPE (TREE_TYPE (m)), idx * size);
      tem = build3 (BIT_FIELD_REF, TREE_TYPE (op),
		    unshare_expr (p), op1, index);
      gimple_assign_set_rhs1 (stmt, tem);
      fold_stmt (gsi);
      update_stmt (gsi_stmt (*gsi));
      return true;
    }

  return false;
}

/* Determine whether applying the 2 permutations (mask1 then mask2)
   gives back one of the input.  */

static int
is_combined_permutation_identity (tree mask1, tree mask2)
{
  tree mask;
  unsigned int nelts, i, j;
  bool maybe_identity1 = true;
  bool maybe_identity2 = true;

  gcc_checking_assert (TREE_CODE (mask1) == VECTOR_CST
		       && TREE_CODE (mask2) == VECTOR_CST);
  mask = fold_ternary (VEC_PERM_EXPR, TREE_TYPE (mask1), mask1, mask1, mask2);
  gcc_assert (TREE_CODE (mask) == VECTOR_CST);

  nelts = VECTOR_CST_NELTS (mask);
  for (i = 0; i < nelts; i++)
    {
      tree val = VECTOR_CST_ELT (mask, i);
      gcc_assert (TREE_CODE (val) == INTEGER_CST);
      j = TREE_INT_CST_LOW (val) & (2 * nelts - 1);
      if (j == i)
	maybe_identity2 = false;
      else if (j == i + nelts)
	maybe_identity1 = false;
      else
	return 0;
    }
  return maybe_identity1 ? 1 : maybe_identity2 ? 2 : 0;
}

/* Combine a shuffle with its arguments.  Returns 1 if there were any
   changes made, 2 if cfg-cleanup needs to run.  Else it returns 0.  */
 
static int
simplify_permutation (gimple_stmt_iterator *gsi)
{
  gimple stmt = gsi_stmt (*gsi);
  gimple def_stmt;
  tree op0, op1, op2, op3, arg0, arg1;
  enum tree_code code;
  bool single_use_op0 = false;

  gcc_checking_assert (gimple_assign_rhs_code (stmt) == VEC_PERM_EXPR);

  op0 = gimple_assign_rhs1 (stmt);
  op1 = gimple_assign_rhs2 (stmt);
  op2 = gimple_assign_rhs3 (stmt);

  if (TREE_CODE (op2) != VECTOR_CST)
    return 0;

  if (TREE_CODE (op0) == VECTOR_CST)
    {
      code = VECTOR_CST;
      arg0 = op0;
    }
  else if (TREE_CODE (op0) == SSA_NAME)
    {
      def_stmt = get_prop_source_stmt (op0, false, &single_use_op0);
      if (!def_stmt || !can_propagate_from (def_stmt))
	return 0;

      code = gimple_assign_rhs_code (def_stmt);
      arg0 = gimple_assign_rhs1 (def_stmt);
    }
  else
    return 0;

  /* Two consecutive shuffles.  */
  if (code == VEC_PERM_EXPR)
    {
      tree orig;
      int ident;

      if (op0 != op1)
	return 0;
      op3 = gimple_assign_rhs3 (def_stmt);
      if (TREE_CODE (op3) != VECTOR_CST)
	return 0;
      ident = is_combined_permutation_identity (op3, op2);
      if (!ident)
	return 0;
      orig = (ident == 1) ? gimple_assign_rhs1 (def_stmt)
			  : gimple_assign_rhs2 (def_stmt);
      gimple_assign_set_rhs1 (stmt, unshare_expr (orig));
      gimple_assign_set_rhs_code (stmt, TREE_CODE (orig));
      gimple_set_num_ops (stmt, 2);
      update_stmt (stmt);
      return remove_prop_source_from_use (op0) ? 2 : 1;
    }

  /* Shuffle of a constructor.  */
  else if (code == CONSTRUCTOR || code == VECTOR_CST)
    {
      tree opt;
      bool ret = false;
      if (op0 != op1)
	{
	  if (TREE_CODE (op0) == SSA_NAME && !single_use_op0)
	    return 0;

	  if (TREE_CODE (op1) == VECTOR_CST)
	    arg1 = op1;
	  else if (TREE_CODE (op1) == SSA_NAME)
	    {
	      enum tree_code code2;

	      gimple def_stmt2 = get_prop_source_stmt (op1, true, NULL);
	      if (!def_stmt2 || !can_propagate_from (def_stmt2))
		return 0;

	      code2 = gimple_assign_rhs_code (def_stmt2);
	      if (code2 != CONSTRUCTOR && code2 != VECTOR_CST)
		return 0;
	      arg1 = gimple_assign_rhs1 (def_stmt2);
	    }
	  else
	    return 0;
	}
      else
	{
	  /* Already used twice in this statement.  */
	  if (TREE_CODE (op0) == SSA_NAME && num_imm_uses (op0) > 2)
	    return 0;
	  arg1 = arg0;
	}
      opt = fold_ternary (VEC_PERM_EXPR, TREE_TYPE (op0), arg0, arg1, op2);
      if (!opt
	  || (TREE_CODE (opt) != CONSTRUCTOR && TREE_CODE (opt) != VECTOR_CST))
	return 0;
      gimple_assign_set_rhs_from_tree (gsi, opt);
      update_stmt (gsi_stmt (*gsi));
      if (TREE_CODE (op0) == SSA_NAME)
	ret = remove_prop_source_from_use (op0);
      if (op0 != op1 && TREE_CODE (op1) == SSA_NAME)
	ret |= remove_prop_source_from_use (op1);
      return ret ? 2 : 1;
    }

  return 0;
}

/* Recognize a VEC_PERM_EXPR.  Returns true if there were any changes.  */

static bool
simplify_vector_constructor (gimple_stmt_iterator *gsi)
{
  gimple stmt = gsi_stmt (*gsi);
  gimple def_stmt;
  tree op, op2, orig, type, elem_type;
  unsigned elem_size, nelts, i;
  enum tree_code code;
  constructor_elt *elt;
  unsigned char *sel;
  bool maybe_ident;

  gcc_checking_assert (gimple_assign_rhs_code (stmt) == CONSTRUCTOR);

  op = gimple_assign_rhs1 (stmt);
  type = TREE_TYPE (op);
  gcc_checking_assert (TREE_CODE (type) == VECTOR_TYPE);

  nelts = TYPE_VECTOR_SUBPARTS (type);
  elem_type = TREE_TYPE (type);
  elem_size = TREE_INT_CST_LOW (TYPE_SIZE (elem_type));

  sel = XALLOCAVEC (unsigned char, nelts);
  orig = NULL;
  maybe_ident = true;
  FOR_EACH_VEC_SAFE_ELT (CONSTRUCTOR_ELTS (op), i, elt)
    {
      tree ref, op1;

      if (i >= nelts)
	return false;

      if (TREE_CODE (elt->value) != SSA_NAME)
	return false;
      def_stmt = get_prop_source_stmt (elt->value, false, NULL);
      if (!def_stmt)
	return false;
      code = gimple_assign_rhs_code (def_stmt);
      if (code != BIT_FIELD_REF)
	return false;
      op1 = gimple_assign_rhs1 (def_stmt);
      ref = TREE_OPERAND (op1, 0);
      if (orig)
	{
	  if (ref != orig)
	    return false;
	}
      else
	{
	  if (TREE_CODE (ref) != SSA_NAME)
	    return false;
	  if (!useless_type_conversion_p (type, TREE_TYPE (ref)))
	    return false;
	  orig = ref;
	}
      if (TREE_INT_CST_LOW (TREE_OPERAND (op1, 1)) != elem_size)
	return false;
      sel[i] = TREE_INT_CST_LOW (TREE_OPERAND (op1, 2)) / elem_size;
      if (sel[i] != i) maybe_ident = false;
    }
  if (i < nelts)
    return false;

  if (maybe_ident)
    gimple_assign_set_rhs_from_tree (gsi, orig);
  else
    {
      tree mask_type, *mask_elts;

      if (!can_vec_perm_p (TYPE_MODE (type), false, sel))
	return false;
      mask_type
	= build_vector_type (build_nonstandard_integer_type (elem_size, 1),
			     nelts);
      if (GET_MODE_CLASS (TYPE_MODE (mask_type)) != MODE_VECTOR_INT
	  || GET_MODE_SIZE (TYPE_MODE (mask_type))
	     != GET_MODE_SIZE (TYPE_MODE (type)))
	return false;
      mask_elts = XALLOCAVEC (tree, nelts);
      for (i = 0; i < nelts; i++)
	mask_elts[i] = build_int_cst (TREE_TYPE (mask_type), sel[i]);
      op2 = build_vector (mask_type, mask_elts);
      gimple_assign_set_rhs_with_ops (gsi, VEC_PERM_EXPR, orig, orig, op2);
    }
  update_stmt (gsi_stmt (*gsi));
  return true;
}


/* Primitive "lattice" function for gimple_simplify.  */

static tree
fwprop_ssa_val (tree name)
{
  /* First valueize NAME.  */
  if (TREE_CODE (name) == SSA_NAME
      && SSA_NAME_VERSION (name) < lattice.length ())
    {
      tree val = lattice[SSA_NAME_VERSION (name)];
      if (val)
	name = val;
    }
  /* We continue matching along SSA use-def edges for SSA names
     that are not single-use.  Currently there are no patterns
     that would cause any issues with that.  */
  return name;
}

/* Main entry point for the forward propagation and statement combine
   optimizer.  */

namespace {

const pass_data pass_data_forwprop =
{
  GIMPLE_PASS, /* type */
  "forwprop", /* name */
  OPTGROUP_NONE, /* optinfo_flags */
  TV_TREE_FORWPROP, /* tv_id */
  ( PROP_cfg | PROP_ssa ), /* properties_required */
  0, /* properties_provided */
  0, /* properties_destroyed */
  0, /* todo_flags_start */
  TODO_update_ssa, /* todo_flags_finish */
};

class pass_forwprop : public gimple_opt_pass
{
public:
  pass_forwprop (gcc::context *ctxt)
    : gimple_opt_pass (pass_data_forwprop, ctxt)
  {}

  /* opt_pass methods: */
  opt_pass * clone () { return new pass_forwprop (m_ctxt); }
  virtual bool gate (function *) { return flag_tree_forwprop; }
  virtual unsigned int execute (function *);

}; // class pass_forwprop

unsigned int
pass_forwprop::execute (function *fun)
{
  unsigned int todoflags = 0;

  cfg_changed = false;

  /* Combine stmts with the stmts defining their operands.  Do that
     in an order that guarantees visiting SSA defs before SSA uses.  */
  lattice.create (num_ssa_names);
  lattice.quick_grow_cleared (num_ssa_names);
  int *postorder = XNEWVEC (int, n_basic_blocks_for_fn (fun));
  int postorder_num = inverted_post_order_compute (postorder);
  auto_vec<gimple, 4> to_fixup;
  to_purge = BITMAP_ALLOC (NULL);
  for (int i = 0; i < postorder_num; ++i)
    {
      gimple_stmt_iterator gsi;
      basic_block bb = BASIC_BLOCK_FOR_FN (fun, postorder[i]);

      /* Apply forward propagation to all stmts in the basic-block.
	 Note we update GSI within the loop as necessary.  */
      for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); )
	{
	  gimple stmt = gsi_stmt (gsi);
	  tree lhs, rhs;
	  enum tree_code code;

	  if (!is_gimple_assign (stmt))
	    {
	      gsi_next (&gsi);
	      continue;
	    }

	  lhs = gimple_assign_lhs (stmt);
	  rhs = gimple_assign_rhs1 (stmt);
	  code = gimple_assign_rhs_code (stmt);
	  if (TREE_CODE (lhs) != SSA_NAME
	      || has_zero_uses (lhs))
	    {
	      gsi_next (&gsi);
	      continue;
	    }

	  /* If this statement sets an SSA_NAME to an address,
	     try to propagate the address into the uses of the SSA_NAME.  */
	  if (code == ADDR_EXPR
	      /* Handle pointer conversions on invariant addresses
		 as well, as this is valid gimple.  */
	      || (CONVERT_EXPR_CODE_P (code)
		  && TREE_CODE (rhs) == ADDR_EXPR
		  && POINTER_TYPE_P (TREE_TYPE (lhs))))
	    {
	      tree base = get_base_address (TREE_OPERAND (rhs, 0));
	      if ((!base
		   || !DECL_P (base)
		   || decl_address_invariant_p (base))
		  && !stmt_references_abnormal_ssa_name (stmt)
		  && forward_propagate_addr_expr (lhs, rhs, true))
		{
		  fwprop_invalidate_lattice (gimple_get_lhs (stmt));
		  release_defs (stmt);
		  gsi_remove (&gsi, true);
		}
	      else
		gsi_next (&gsi);
	    }
	  else if (code == POINTER_PLUS_EXPR)
	    {
	      tree off = gimple_assign_rhs2 (stmt);
	      if (TREE_CODE (off) == INTEGER_CST
		  && can_propagate_from (stmt)
		  && !simple_iv_increment_p (stmt)
		  /* ???  Better adjust the interface to that function
		     instead of building new trees here.  */
		  && forward_propagate_addr_expr
		       (lhs,
			build1_loc (gimple_location (stmt),
				    ADDR_EXPR, TREE_TYPE (rhs),
				    fold_build2 (MEM_REF,
						 TREE_TYPE (TREE_TYPE (rhs)),
						 rhs,
						 fold_convert (ptr_type_node,
							       off))), true))
		{
		  fwprop_invalidate_lattice (gimple_get_lhs (stmt));
		  release_defs (stmt);
		  gsi_remove (&gsi, true);
		}
	      else if (is_gimple_min_invariant (rhs))
		{
		  /* Make sure to fold &a[0] + off_1 here.  */
		  fold_stmt_inplace (&gsi);
		  update_stmt (stmt);
		  if (gimple_assign_rhs_code (stmt) == POINTER_PLUS_EXPR)
		    gsi_next (&gsi);
		}
	      else
		gsi_next (&gsi);
	    }
	  else if (TREE_CODE (TREE_TYPE (lhs)) == COMPLEX_TYPE
		   && gimple_assign_load_p (stmt)
		   && !gimple_has_volatile_ops (stmt)
		   && (TREE_CODE (gimple_assign_rhs1 (stmt))
		       != TARGET_MEM_REF)
		   && !stmt_can_throw_internal (stmt))
	    {
	      /* Rewrite loads used only in real/imagpart extractions to
	         component-wise loads.  */
	      use_operand_p use_p;
	      imm_use_iterator iter;
	      bool rewrite = true;
	      FOR_EACH_IMM_USE_FAST (use_p, iter, lhs)
		{
		  gimple use_stmt = USE_STMT (use_p);
		  if (is_gimple_debug (use_stmt))
		    continue;
		  if (!is_gimple_assign (use_stmt)
		      || (gimple_assign_rhs_code (use_stmt) != REALPART_EXPR
			  && gimple_assign_rhs_code (use_stmt) != IMAGPART_EXPR))
		    {
		      rewrite = false;
		      break;
		    }
		}
	      if (rewrite)
		{
		  gimple use_stmt;
		  FOR_EACH_IMM_USE_STMT (use_stmt, iter, lhs)
		    {
		      if (is_gimple_debug (use_stmt))
			{
			  if (gimple_debug_bind_p (use_stmt))
			    {
			      gimple_debug_bind_reset_value (use_stmt);
			      update_stmt (use_stmt);
			    }
			  continue;
			}

		      tree new_rhs = build1 (gimple_assign_rhs_code (use_stmt),
					     TREE_TYPE (TREE_TYPE (rhs)),
					     unshare_expr (rhs));
		      gimple new_stmt
			= gimple_build_assign (gimple_assign_lhs (use_stmt),
					       new_rhs);

		      location_t loc = gimple_location (use_stmt);
		      gimple_set_location (new_stmt, loc);
		      gimple_stmt_iterator gsi2 = gsi_for_stmt (use_stmt);
		      unlink_stmt_vdef (use_stmt);
		      gsi_remove (&gsi2, true);

		      gsi_insert_before (&gsi, new_stmt, GSI_SAME_STMT);
		    }

		  release_defs (stmt);
		  gsi_remove (&gsi, true);
		}
	      else
		gsi_next (&gsi);
	    }
	  else if (code == COMPLEX_EXPR)
	    {
	      /* Rewrite stores of a single-use complex build expression
	         to component-wise stores.  */
	      use_operand_p use_p;
	      gimple use_stmt;
	      if (single_imm_use (lhs, &use_p, &use_stmt)
		  && gimple_store_p (use_stmt)
		  && !gimple_has_volatile_ops (use_stmt)
		  && is_gimple_assign (use_stmt)
		  && (TREE_CODE (gimple_assign_lhs (use_stmt))
		      != TARGET_MEM_REF))
		{
		  tree use_lhs = gimple_assign_lhs (use_stmt);
		  tree new_lhs = build1 (REALPART_EXPR,
					 TREE_TYPE (TREE_TYPE (use_lhs)),
					 unshare_expr (use_lhs));
		  gimple new_stmt = gimple_build_assign (new_lhs, rhs);
		  location_t loc = gimple_location (use_stmt);
		  gimple_set_location (new_stmt, loc);
		  gimple_set_vuse (new_stmt, gimple_vuse (use_stmt));
		  gimple_set_vdef (new_stmt, make_ssa_name (gimple_vop (cfun)));
		  SSA_NAME_DEF_STMT (gimple_vdef (new_stmt)) = new_stmt;
		  gimple_set_vuse (use_stmt, gimple_vdef (new_stmt));
		  gimple_stmt_iterator gsi2 = gsi_for_stmt (use_stmt);
		  gsi_insert_before (&gsi2, new_stmt, GSI_SAME_STMT);

		  new_lhs = build1 (IMAGPART_EXPR,
				    TREE_TYPE (TREE_TYPE (use_lhs)),
				    unshare_expr (use_lhs));
		  gimple_assign_set_lhs (use_stmt, new_lhs);
		  gimple_assign_set_rhs1 (use_stmt, gimple_assign_rhs2 (stmt));
		  update_stmt (use_stmt);

		  release_defs (stmt);
		  gsi_remove (&gsi, true);
		}
	      else
		gsi_next (&gsi);
	    }
	  else
	    gsi_next (&gsi);
	}

      /* Combine stmts with the stmts defining their operands.
	 Note we update GSI within the loop as necessary.  */
      for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi);)
	{
	  gimple stmt = gsi_stmt (gsi);
	  gimple orig_stmt = stmt;
	  bool changed = false;
	  bool was_noreturn = (is_gimple_call (stmt)
			       && gimple_call_noreturn_p (stmt));

	  /* Mark stmt as potentially needing revisiting.  */
	  gimple_set_plf (stmt, GF_PLF_1, false);

	  if (fold_stmt (&gsi, fwprop_ssa_val))
	    {
	      changed = true;
	      stmt = gsi_stmt (gsi);
	      if (maybe_clean_or_replace_eh_stmt (orig_stmt, stmt))
		bitmap_set_bit (to_purge, bb->index);
	      if (!was_noreturn
		  && is_gimple_call (stmt) && gimple_call_noreturn_p (stmt))
		to_fixup.safe_push (stmt);
	      /* Cleanup the CFG if we simplified a condition to
	         true or false.  */
	      if (gcond *cond = dyn_cast <gcond *> (stmt))
		if (gimple_cond_true_p (cond)
		    || gimple_cond_false_p (cond))
		  cfg_changed = true;
	      update_stmt (stmt);
	    }

	  switch (gimple_code (stmt))
	    {
	    case GIMPLE_ASSIGN:
	      {
		tree rhs1 = gimple_assign_rhs1 (stmt);
		enum tree_code code = gimple_assign_rhs_code (stmt);

		if (code == COND_EXPR
		    || code == VEC_COND_EXPR)
		  {
		    /* In this case the entire COND_EXPR is in rhs1. */
		    if (forward_propagate_into_cond (&gsi))
		      {
			changed = true;
			stmt = gsi_stmt (gsi);
		      }
		  }
		else if (TREE_CODE_CLASS (code) == tcc_comparison)
		  {
		    int did_something;
		    did_something = forward_propagate_into_comparison (&gsi);
		    if (did_something == 2)
		      cfg_changed = true;
		    changed = did_something != 0;
		  }
		else if ((code == PLUS_EXPR
			  || code == BIT_IOR_EXPR
			  || code == BIT_XOR_EXPR)
			 && simplify_rotate (&gsi))
		  changed = true;
		else if (code == VEC_PERM_EXPR)
		  {
		    int did_something = simplify_permutation (&gsi);
		    if (did_something == 2)
		      cfg_changed = true;
		    changed = did_something != 0;
		  }
		else if (code == BIT_FIELD_REF)
		  changed = simplify_bitfield_ref (&gsi);
                else if (code == CONSTRUCTOR
                         && TREE_CODE (TREE_TYPE (rhs1)) == VECTOR_TYPE)
                  changed = simplify_vector_constructor (&gsi);
		break;
	      }

	    case GIMPLE_SWITCH:
	      changed = simplify_gimple_switch (as_a <gswitch *> (stmt));
	      break;

	    case GIMPLE_COND:
	      {
		int did_something
		  = forward_propagate_into_gimple_cond (as_a <gcond *> (stmt));
		if (did_something == 2)
		  cfg_changed = true;
		changed = did_something != 0;
		break;
	      }

	    case GIMPLE_CALL:
	      {
		tree callee = gimple_call_fndecl (stmt);
		if (callee != NULL_TREE
		    && DECL_BUILT_IN_CLASS (callee) == BUILT_IN_NORMAL)
		  changed = simplify_builtin_call (&gsi, callee);
		break;
	      }

	    default:;
	    }

	  if (changed)
	    {
	      /* If the stmt changed then re-visit it and the statements
		 inserted before it.  */
	      for (; !gsi_end_p (gsi); gsi_prev (&gsi))
		if (gimple_plf (gsi_stmt (gsi), GF_PLF_1))
		  break;
	      if (gsi_end_p (gsi))
		gsi = gsi_start_bb (bb);
	      else
		gsi_next (&gsi);
	    }
	  else
	    {
	      /* Stmt no longer needs to be revisited.  */
	      gimple_set_plf (stmt, GF_PLF_1, true);

	      /* Fill up the lattice.  */
	      if (gimple_assign_single_p (stmt))
		{
		  tree lhs = gimple_assign_lhs (stmt);
		  tree rhs = gimple_assign_rhs1 (stmt);
		  if (TREE_CODE (lhs) == SSA_NAME)
		    {
		      tree val = lhs;
		      if (TREE_CODE (rhs) == SSA_NAME)
			val = fwprop_ssa_val (rhs);
		      else if (is_gimple_min_invariant (rhs))
			val = rhs;
		      fwprop_set_lattice_val (lhs, val);
		    }
		}

	      gsi_next (&gsi);
	    }
	}
    }
  free (postorder);
  lattice.release ();

  /* Fixup stmts that became noreturn calls.  This may require splitting
     blocks and thus isn't possible during the walk.  Do this
     in reverse order so we don't inadvertedly remove a stmt we want to
     fixup by visiting a dominating now noreturn call first.  */
  while (!to_fixup.is_empty ())
    {
      gimple stmt = to_fixup.pop ();
      if (dump_file && dump_flags & TDF_DETAILS)
	{
	  fprintf (dump_file, "Fixing up noreturn call ");
	  print_gimple_stmt (dump_file, stmt, 0, 0);
	  fprintf (dump_file, "\n");
	}
      cfg_changed |= fixup_noreturn_call (stmt);
    }

  cfg_changed |= gimple_purge_all_dead_eh_edges (to_purge);
  BITMAP_FREE (to_purge);

  if (cfg_changed)
    todoflags |= TODO_cleanup_cfg;

  return todoflags;
}

} // anon namespace

gimple_opt_pass *
make_pass_forwprop (gcc::context *ctxt)
{
  return new pass_forwprop (ctxt);
}