summaryrefslogtreecommitdiff
path: root/gcc/ipa-polymorphic-call.c
blob: a577ffab68dff59f815cefd80e7d1addf5fdb1a0 (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
2511
2512
2513
2514
2515
2516
2517
2518
/* Analysis of polymorphic call context.
   Copyright (C) 2013-2015 Free Software Foundation, Inc.
   Contributed by Jan Hubicka

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 "backend.h"
#include "rtl.h"
#include "tree.h"
#include "gimple.h"
#include "tree-pass.h"
#include "tree-ssa-operands.h"
#include "streamer-hooks.h"
#include "cgraph.h"
#include "data-streamer.h"
#include "diagnostic.h"
#include "alias.h"
#include "fold-const.h"
#include "calls.h"
#include "ipa-utils.h"
#include "tree-dfa.h"
#include "gimple-pretty-print.h"
#include "tree-into-ssa.h"

/* Return true when TYPE contains an polymorphic type and thus is interesting
   for devirtualization machinery.  */

static bool contains_type_p (tree, HOST_WIDE_INT, tree,
			     bool consider_placement_new = true,
			     bool consider_bases = true);

bool
contains_polymorphic_type_p (const_tree type)
{
  type = TYPE_MAIN_VARIANT (type);

  if (RECORD_OR_UNION_TYPE_P (type))
    {
      if (TYPE_BINFO (type)
          && polymorphic_type_binfo_p (TYPE_BINFO (type)))
	return true;
      for (tree fld = TYPE_FIELDS (type); fld; fld = DECL_CHAIN (fld))
	if (TREE_CODE (fld) == FIELD_DECL
	    && !DECL_ARTIFICIAL (fld)
	    && contains_polymorphic_type_p (TREE_TYPE (fld)))
	  return true;
      return false;
    }
  if (TREE_CODE (type) == ARRAY_TYPE)
    return contains_polymorphic_type_p (TREE_TYPE (type));
  return false;
}

/* Return true if it seems valid to use placement new to build EXPECTED_TYPE
   at possition CUR_OFFSET within TYPE.  

   POD can be changed to an instance of a polymorphic type by
   placement new.  Here we play safe and assume that any
   non-polymorphic type is POD.  */
bool
possible_placement_new (tree type, tree expected_type,
			HOST_WIDE_INT cur_offset)
{
  if (cur_offset < 0)
    return true;
  return ((TREE_CODE (type) != RECORD_TYPE
	   || !TYPE_BINFO (type)
	   || cur_offset >= POINTER_SIZE
	   || !polymorphic_type_binfo_p (TYPE_BINFO (type)))
	  && (!TYPE_SIZE (type)
	      || !tree_fits_shwi_p (TYPE_SIZE (type))
	      || (cur_offset
		  + (expected_type ? tree_to_uhwi (TYPE_SIZE (expected_type))
		     : POINTER_SIZE)
		  <= tree_to_uhwi (TYPE_SIZE (type)))));
}

/* THIS->OUTER_TYPE is a type of memory object where object of OTR_TYPE
   is contained at THIS->OFFSET.  Walk the memory representation of
   THIS->OUTER_TYPE and find the outermost class type that match
   OTR_TYPE or contain OTR_TYPE as a base.  Update THIS
   to represent it.

   If OTR_TYPE is NULL, just find outermost polymorphic type with
   virtual table present at possition OFFSET.

   For example when THIS represents type
   class A
     {
       int a;
       class B b;
     }
   and we look for type at offset sizeof(int), we end up with B and offset 0.
   If the same is produced by multiple inheritance, we end up with A and offset
   sizeof(int). 

   If we can not find corresponding class, give up by setting
   THIS->OUTER_TYPE to OTR_TYPE and THIS->OFFSET to NULL. 
   Return true when lookup was sucesful.

   When CONSIDER_PLACEMENT_NEW is false, reject contexts that may be made
   valid only via alocation of new polymorphic type inside by means
   of placement new.

   When CONSIDER_BASES is false, only look for actual fields, not base types
   of TYPE.  */

bool
ipa_polymorphic_call_context::restrict_to_inner_class (tree otr_type,
						       bool consider_placement_new,
						       bool consider_bases)
{
  tree type = outer_type;
  HOST_WIDE_INT cur_offset = offset;
  bool speculative = false;
  bool size_unknown = false;
  unsigned HOST_WIDE_INT otr_type_size = POINTER_SIZE;

  /* Update OUTER_TYPE to match EXPECTED_TYPE if it is not set.  */
  if (!outer_type)
    {
      clear_outer_type (otr_type);
      type = otr_type;
      cur_offset = 0;
    }
 /* See if OFFSET points inside OUTER_TYPE.  If it does not, we know
    that the context is either invalid, or the instance type must be
    derived from OUTER_TYPE.

    Because the instance type may contain field whose type is of OUTER_TYPE,
    we can not derive any effective information about it.

    TODO: In the case we know all derrived types, we can definitely do better
    here.  */
  else if (TYPE_SIZE (outer_type)
	   && tree_fits_shwi_p (TYPE_SIZE (outer_type))
	   && tree_to_shwi (TYPE_SIZE (outer_type)) >= 0
	   && tree_to_shwi (TYPE_SIZE (outer_type)) <= offset)
   {
     bool der = maybe_derived_type; /* clear_outer_type will reset it.  */
     bool dyn = dynamic;
     clear_outer_type (otr_type);
     type = otr_type;
     cur_offset = 0;

     /* If derived type is not allowed, we know that the context is invalid.
	For dynamic types, we really do not have information about
	size of the memory location.  It is possible that completely
	different type is stored after outer_type.  */
     if (!der && !dyn)
       {
	 clear_speculation ();
	 invalid = true;
	 return false;
       }
   }

  if (otr_type && TYPE_SIZE (otr_type)
      && tree_fits_shwi_p (TYPE_SIZE (otr_type)))
    otr_type_size = tree_to_uhwi (TYPE_SIZE (otr_type));

  if (!type || offset < 0)
    goto no_useful_type_info;

  /* Find the sub-object the constant actually refers to and mark whether it is
     an artificial one (as opposed to a user-defined one).

     This loop is performed twice; first time for outer_type and second time
     for speculative_outer_type.  The second run has SPECULATIVE set.  */
  while (true)
    {
      unsigned HOST_WIDE_INT pos, size;
      tree fld;

      /* If we do not know size of TYPE, we need to be more conservative
         about accepting cases where we can not find EXPECTED_TYPE.
	 Generally the types that do matter here are of constant size.
	 Size_unknown case should be very rare.  */
      if (TYPE_SIZE (type)
	  && tree_fits_shwi_p (TYPE_SIZE (type))
	  && tree_to_shwi (TYPE_SIZE (type)) >= 0)
	size_unknown = false;
      else
	size_unknown = true;

      /* On a match, just return what we found.  */
      if ((otr_type
	   && types_odr_comparable (type, otr_type)
	   && types_same_for_odr (type, otr_type))
	  || (!otr_type
	      && TREE_CODE (type) == RECORD_TYPE
	      && TYPE_BINFO (type)
	      && polymorphic_type_binfo_p (TYPE_BINFO (type))))
	{
	  if (speculative)
	    {
	      /* If we did not match the offset, just give up on speculation.  */
	      if (cur_offset != 0
		  /* Also check if speculation did not end up being same as
		     non-speculation.  */
		  || (types_must_be_same_for_odr (speculative_outer_type,
						  outer_type)
		      && (maybe_derived_type
			  == speculative_maybe_derived_type)))
		clear_speculation ();
	      return true;
	    }
	  else
	    {
	      /* If type is known to be final, do not worry about derived
		 types.  Testing it here may help us to avoid speculation.  */
	      if (otr_type && TREE_CODE (outer_type) == RECORD_TYPE
		  && (!in_lto_p || odr_type_p (outer_type))
		  && type_with_linkage_p (outer_type)
		  && type_known_to_have_no_derivations_p (outer_type))
		maybe_derived_type = false;

	      /* Type can not contain itself on an non-zero offset.  In that case
		 just give up.  Still accept the case where size is now known.
		 Either the second copy may appear past the end of type or within
		 the non-POD buffer located inside the variably sized type
		 itself.  */
	      if (cur_offset != 0)
		goto no_useful_type_info;
	      /* If we determined type precisely or we have no clue on
 		 speuclation, we are done.  */
	      if (!maybe_derived_type || !speculative_outer_type
		  || !speculation_consistent_p (speculative_outer_type,
					        speculative_offset,
					        speculative_maybe_derived_type,
						otr_type))
		{
		  clear_speculation ();
	          return true;
		}
	      /* Otherwise look into speculation now.  */
	      else
		{
		  speculative = true;
		  type = speculative_outer_type;
		  cur_offset = speculative_offset;
		  continue;
		}
	    }
	}

      /* Walk fields and find corresponding on at OFFSET.  */
      if (TREE_CODE (type) == RECORD_TYPE)
	{
	  for (fld = TYPE_FIELDS (type); fld; fld = DECL_CHAIN (fld))
	    {
	      if (TREE_CODE (fld) != FIELD_DECL)
		continue;

	      pos = int_bit_position (fld);
	      if (pos > (unsigned HOST_WIDE_INT)cur_offset)
		continue;

	      /* Do not consider vptr itself.  Not even for placement new.  */
	      if (!pos && DECL_ARTIFICIAL (fld)
		  && POINTER_TYPE_P (TREE_TYPE (fld))
		  && TYPE_BINFO (type)
		  && polymorphic_type_binfo_p (TYPE_BINFO (type)))
		continue;

	      if (!DECL_SIZE (fld) || !tree_fits_uhwi_p (DECL_SIZE (fld)))
		goto no_useful_type_info;
	      size = tree_to_uhwi (DECL_SIZE (fld));

	      /* We can always skip types smaller than pointer size:
		 those can not contain a virtual table pointer.

		 Disqualifying fields that are too small to fit OTR_TYPE
		 saves work needed to walk them for no benefit.
		 Because of the way the bases are packed into a class, the
		 field's size may be smaller than type size, so it needs
		 to be done with a care.  */
		
	      if (pos <= (unsigned HOST_WIDE_INT)cur_offset
		  && (pos + size) >= (unsigned HOST_WIDE_INT)cur_offset
				     + POINTER_SIZE
		  && (!otr_type
		      || !TYPE_SIZE (TREE_TYPE (fld))
		      || !tree_fits_shwi_p (TYPE_SIZE (TREE_TYPE (fld)))
		      || (pos + tree_to_uhwi (TYPE_SIZE (TREE_TYPE (fld))))
			  >= cur_offset + otr_type_size))
		break;
	    }

	  if (!fld)
	    goto no_useful_type_info;

	  type = TYPE_MAIN_VARIANT (TREE_TYPE (fld));
	  cur_offset -= pos;
	  /* DECL_ARTIFICIAL represents a basetype.  */
	  if (!DECL_ARTIFICIAL (fld))
	    {
	      if (!speculative)
		{
		  outer_type = type;
		  offset = cur_offset;
		  /* As soon as we se an field containing the type,
		     we know we are not looking for derivations.  */
		  maybe_derived_type = false;
		}
	      else
		{
		  speculative_outer_type = type;
		  speculative_offset = cur_offset;
		  speculative_maybe_derived_type = false;
		}
	    }
	  else if (!consider_bases)
	    goto no_useful_type_info;
	}
      else if (TREE_CODE (type) == ARRAY_TYPE)
	{
	  tree subtype = TYPE_MAIN_VARIANT (TREE_TYPE (type));

	  /* Give up if we don't know array field size.
	     Also give up on non-polymorphic types as they are used
	     as buffers for placement new.  */
	  if (!TYPE_SIZE (subtype)
	      || !tree_fits_shwi_p (TYPE_SIZE (subtype))
	      || tree_to_shwi (TYPE_SIZE (subtype)) <= 0
	      || !contains_polymorphic_type_p (subtype))
	    goto no_useful_type_info;

	  HOST_WIDE_INT new_offset = cur_offset % tree_to_shwi (TYPE_SIZE (subtype));

	  /* We may see buffer for placement new.  In this case the expected type
	     can be bigger than the subtype.  */
	  if (TYPE_SIZE (subtype)
	      && (cur_offset + otr_type_size
		  > tree_to_uhwi (TYPE_SIZE (subtype))))
	    goto no_useful_type_info;

	  cur_offset = new_offset;
	  type = TYPE_MAIN_VARIANT (subtype);
	  if (!speculative)
	    {
	      outer_type = type;
	      offset = cur_offset;
	      maybe_derived_type = false;
	    }
	  else
	    {
	      speculative_outer_type = type;
	      speculative_offset = cur_offset;
	      speculative_maybe_derived_type = false;
	    }
	}
      /* Give up on anything else.  */
      else
	{
no_useful_type_info:
	  if (maybe_derived_type && !speculative
	      && TREE_CODE (outer_type) == RECORD_TYPE
	      && TREE_CODE (otr_type) == RECORD_TYPE
	      && TYPE_BINFO (otr_type)
	      && !offset
	      && get_binfo_at_offset (TYPE_BINFO (otr_type), 0, outer_type))
	    {
	      clear_outer_type (otr_type);
	      if (!speculative_outer_type
		  || !speculation_consistent_p (speculative_outer_type,
						speculative_offset,
					        speculative_maybe_derived_type,
						otr_type))
		clear_speculation ();
	      if (speculative_outer_type)
		{
		  speculative = true;
		  type = speculative_outer_type;
		  cur_offset = speculative_offset;
		}
	      else
		return true;
	    }
	  /* We found no way to embedd EXPECTED_TYPE in TYPE.
	     We still permit two special cases - placement new and
	     the case of variadic types containing themselves.  */
	  if (!speculative
	      && consider_placement_new
	      && (size_unknown || !type || maybe_derived_type
		  || possible_placement_new (type, otr_type, cur_offset)))
	    {
	      /* In these weird cases we want to accept the context.
		 In non-speculative run we have no useful outer_type info
		 (TODO: we may eventually want to record upper bound on the
		  type size that can be used to prune the walk),
		 but we still want to consider speculation that may
		 give useful info.  */
	      if (!speculative)
		{
		  clear_outer_type (otr_type);
		  if (!speculative_outer_type
		      || !speculation_consistent_p (speculative_outer_type,
						    speculative_offset,
						    speculative_maybe_derived_type,
						    otr_type))
		    clear_speculation ();
		  if (speculative_outer_type)
		    {
		      speculative = true;
		      type = speculative_outer_type;
		      cur_offset = speculative_offset;
		    }
		  else
		    return true;
		}
	      else
		{
		  clear_speculation ();
	          return true;
		}
	    }
	  else
	    {
	      clear_speculation ();
	      if (speculative)
		return true;
	      clear_outer_type (otr_type);
	      invalid = true; 
	      return false;
	    }
	}
    }
}

/* Return true if OUTER_TYPE contains OTR_TYPE at OFFSET.
   CONSIDER_PLACEMENT_NEW makes function to accept cases where OTR_TYPE can
   be built within OUTER_TYPE by means of placement new.  CONSIDER_BASES makes
   function to accept cases where OTR_TYPE appears as base of OUTER_TYPE or as
   base of one of fields of OUTER_TYPE.  */

static bool
contains_type_p (tree outer_type, HOST_WIDE_INT offset,
		 tree otr_type,
		 bool consider_placement_new,
		 bool consider_bases)
{
  ipa_polymorphic_call_context context;

  /* Check that type is within range.  */
  if (offset < 0)
    return false;
  if (TYPE_SIZE (outer_type) && TYPE_SIZE (otr_type)
      && TREE_CODE (TYPE_SIZE (outer_type)) == INTEGER_CST
      && TREE_CODE (TYPE_SIZE (otr_type)) == INTEGER_CST
      && wi::ltu_p (wi::to_offset (TYPE_SIZE (outer_type)),
		    (wi::to_offset (TYPE_SIZE (otr_type)) + offset)))
    return false;

  context.offset = offset;
  context.outer_type = TYPE_MAIN_VARIANT (outer_type);
  context.maybe_derived_type = false;
  context.dynamic = false;
  return context.restrict_to_inner_class (otr_type, consider_placement_new,
					  consider_bases);
}


/* Return a FUNCTION_DECL if BLOCK represents a constructor or destructor.
   If CHECK_CLONES is true, also check for clones of ctor/dtors.  */

tree
inlined_polymorphic_ctor_dtor_block_p (tree block, bool check_clones)
{
  tree fn = BLOCK_ABSTRACT_ORIGIN (block);
  if (fn == NULL || TREE_CODE (fn) != FUNCTION_DECL)
    return NULL_TREE;

  if (TREE_CODE (TREE_TYPE (fn)) != METHOD_TYPE
      || (!DECL_CXX_CONSTRUCTOR_P (fn) && !DECL_CXX_DESTRUCTOR_P (fn)))
    {
      if (!check_clones)
	return NULL_TREE;

      /* Watch for clones where we constant propagated the first
	 argument (pointer to the instance).  */
      fn = DECL_ABSTRACT_ORIGIN (fn);
      if (!fn
	  || TREE_CODE (TREE_TYPE (fn)) != METHOD_TYPE
	  || (!DECL_CXX_CONSTRUCTOR_P (fn) && !DECL_CXX_DESTRUCTOR_P (fn)))
	return NULL_TREE;
    }

  if (flags_from_decl_or_type (fn) & (ECF_PURE | ECF_CONST))
    return NULL_TREE;

  return fn;
}


/* We know that the instance is stored in variable or parameter
   (not dynamically allocated) and we want to disprove the fact
   that it may be in construction at invocation of CALL.

   BASE represents memory location where instance is stored.
   If BASE is NULL, it is assumed to be global memory.
   OUTER_TYPE is known type of the instance or NULL if not
   known.

   For the variable to be in construction we actually need to
   be in constructor of corresponding global variable or
   the inline stack of CALL must contain the constructor.
   Check this condition.  This check works safely only before
   IPA passes, because inline stacks may become out of date
   later.  */

bool
decl_maybe_in_construction_p (tree base, tree outer_type,
			      gimple *call, tree function)
{
  if (outer_type)
    outer_type = TYPE_MAIN_VARIANT (outer_type);
  gcc_assert (!base || DECL_P (base));

  /* After inlining the code unification optimizations may invalidate
     inline stacks.  Also we need to give up on global variables after
     IPA, because addresses of these may have been propagated to their
     constructors.  */
  if (DECL_STRUCT_FUNCTION (function)->after_inlining)
    return true;

  /* Pure functions can not do any changes on the dynamic type;
     that require writting to memory.  */
  if ((!base || !auto_var_in_fn_p (base, function))
      && flags_from_decl_or_type (function) & (ECF_PURE | ECF_CONST))
    return false;

  bool check_clones = !base || is_global_var (base);
  for (tree block = gimple_block (call); block && TREE_CODE (block) == BLOCK;
       block = BLOCK_SUPERCONTEXT (block))
    if (tree fn = inlined_polymorphic_ctor_dtor_block_p (block, check_clones))
      {
	tree type = TYPE_METHOD_BASETYPE (TREE_TYPE (fn));

	if (!outer_type || !types_odr_comparable (type, outer_type))
	  {
	    if (TREE_CODE (type) == RECORD_TYPE
		&& TYPE_BINFO (type)
		&& polymorphic_type_binfo_p (TYPE_BINFO (type)))
	      return true;
	  }
 	else if (types_same_for_odr (type, outer_type))
	  return true;
      }

  if (!base || (TREE_CODE (base) == VAR_DECL && is_global_var (base)))
    {
      if (TREE_CODE (TREE_TYPE (function)) != METHOD_TYPE
	  || (!DECL_CXX_CONSTRUCTOR_P (function)
	      && !DECL_CXX_DESTRUCTOR_P (function)))
	{
	  if (!DECL_ABSTRACT_ORIGIN (function))
	    return false;
	  /* Watch for clones where we constant propagated the first
	     argument (pointer to the instance).  */
	  function = DECL_ABSTRACT_ORIGIN (function);
	  if (!function
	      || TREE_CODE (TREE_TYPE (function)) != METHOD_TYPE
	      || (!DECL_CXX_CONSTRUCTOR_P (function)
		  && !DECL_CXX_DESTRUCTOR_P (function)))
	    return false;
	}
      tree type = TYPE_METHOD_BASETYPE (TREE_TYPE (function));
      if (!outer_type || !types_odr_comparable (type, outer_type))
	{
	  if (TREE_CODE (type) == RECORD_TYPE
	      && TYPE_BINFO (type)
	      && polymorphic_type_binfo_p (TYPE_BINFO (type)))
	    return true;
	}
      else if (types_same_for_odr (type, outer_type))
	return true;
    }
  return false;
}

/* Dump human readable context to F.  If NEWLINE is true, it will be terminated
   by a newline.  */

void
ipa_polymorphic_call_context::dump (FILE *f, bool newline) const
{
  fprintf (f, "    ");
  if (invalid)
    fprintf (f, "Call is known to be undefined");
  else
    {
      if (useless_p ())
	fprintf (f, "nothing known");
      if (outer_type || offset)
	{
	  fprintf (f, "Outer type%s:", dynamic ? " (dynamic)":"");
	  print_generic_expr (f, outer_type, TDF_SLIM);
	  if (maybe_derived_type)
	    fprintf (f, " (or a derived type)");
	  if (maybe_in_construction)
	    fprintf (f, " (maybe in construction)");
	  fprintf (f, " offset " HOST_WIDE_INT_PRINT_DEC,
		   offset);
	}
      if (speculative_outer_type)
	{
	  if (outer_type || offset)
	    fprintf (f, " ");
	  fprintf (f, "Speculative outer type:");
	  print_generic_expr (f, speculative_outer_type, TDF_SLIM);
	  if (speculative_maybe_derived_type)
	    fprintf (f, " (or a derived type)");
	  fprintf (f, " at offset " HOST_WIDE_INT_PRINT_DEC,
		   speculative_offset);
	}
    }
  if (newline)
    fprintf(f, "\n");
}

/* Print context to stderr.  */

void
ipa_polymorphic_call_context::debug () const
{
  dump (stderr);
}

/* Stream out the context to OB.  */

void
ipa_polymorphic_call_context::stream_out (struct output_block *ob) const
{
  struct bitpack_d bp = bitpack_create (ob->main_stream);

  bp_pack_value (&bp, invalid, 1);
  bp_pack_value (&bp, maybe_in_construction, 1);
  bp_pack_value (&bp, maybe_derived_type, 1);
  bp_pack_value (&bp, speculative_maybe_derived_type, 1);
  bp_pack_value (&bp, dynamic, 1);
  bp_pack_value (&bp, outer_type != NULL, 1);
  bp_pack_value (&bp, offset != 0, 1);
  bp_pack_value (&bp, speculative_outer_type != NULL, 1);
  streamer_write_bitpack (&bp);

  if (outer_type != NULL)
    stream_write_tree (ob, outer_type, true);
  if (offset)
    streamer_write_hwi (ob, offset);
  if (speculative_outer_type != NULL)
    {
      stream_write_tree (ob, speculative_outer_type, true);
      streamer_write_hwi (ob, speculative_offset);
    }
  else
    gcc_assert (!speculative_offset);
}

/* Stream in the context from IB and DATA_IN.  */

void
ipa_polymorphic_call_context::stream_in (struct lto_input_block *ib,
					 struct data_in *data_in)
{
  struct bitpack_d bp = streamer_read_bitpack (ib);

  invalid = bp_unpack_value (&bp, 1);
  maybe_in_construction = bp_unpack_value (&bp, 1);
  maybe_derived_type = bp_unpack_value (&bp, 1);
  speculative_maybe_derived_type = bp_unpack_value (&bp, 1);
  dynamic = bp_unpack_value (&bp, 1);
  bool outer_type_p = bp_unpack_value (&bp, 1);
  bool offset_p = bp_unpack_value (&bp, 1);
  bool speculative_outer_type_p = bp_unpack_value (&bp, 1);

  if (outer_type_p)
    outer_type = stream_read_tree (ib, data_in);
  else
    outer_type = NULL;
  if (offset_p)
    offset = (HOST_WIDE_INT) streamer_read_hwi (ib);
  else
    offset = 0;
  if (speculative_outer_type_p)
    {
      speculative_outer_type = stream_read_tree (ib, data_in);
      speculative_offset = (HOST_WIDE_INT) streamer_read_hwi (ib);
    }
  else
    {
      speculative_outer_type = NULL;
      speculative_offset = 0;
    }
}

/* Proudce polymorphic call context for call method of instance
   that is located within BASE (that is assumed to be a decl) at offset OFF. */

void
ipa_polymorphic_call_context::set_by_decl (tree base, HOST_WIDE_INT off)
{
  gcc_assert (DECL_P (base));
  clear_speculation ();

  if (!contains_polymorphic_type_p (TREE_TYPE (base)))
    {
      clear_outer_type ();
      offset = off;
      return;
    }
  outer_type = TYPE_MAIN_VARIANT (TREE_TYPE (base));
  offset = off;
  /* Make very conservative assumption that all objects
     may be in construction. 
 
     It is up to caller to revisit this via
     get_dynamic_type or decl_maybe_in_construction_p.  */
  maybe_in_construction = true;
  maybe_derived_type = false;
  dynamic = false;
}

/* CST is an invariant (address of decl), try to get meaningful
   polymorphic call context for polymorphic call of method 
   if instance of OTR_TYPE that is located at offset OFF of this invariant.
   Return FALSE if nothing meaningful can be found.  */

bool
ipa_polymorphic_call_context::set_by_invariant (tree cst,
						tree otr_type,
						HOST_WIDE_INT off)
{
  HOST_WIDE_INT offset2, size, max_size;
  bool reverse;
  tree base;

  invalid = false;
  off = 0;
  clear_outer_type (otr_type);

  if (TREE_CODE (cst) != ADDR_EXPR)
    return false;

  cst = TREE_OPERAND (cst, 0);
  base = get_ref_base_and_extent (cst, &offset2, &size, &max_size, &reverse);
  if (!DECL_P (base) || max_size == -1 || max_size != size)
    return false;

  /* Only type inconsistent programs can have otr_type that is
     not part of outer type.  */
  if (otr_type && !contains_type_p (TREE_TYPE (base), off, otr_type))
    return false;

  set_by_decl (base, off);
  return true;
}

/* See if OP is SSA name initialized as a copy or by single assignment.
   If so, walk the SSA graph up.  Because simple PHI conditional is considered
   copy, GLOBAL_VISITED may be used to avoid infinite loop walking the SSA
   graph.  */

static tree
walk_ssa_copies (tree op, hash_set<tree> **global_visited = NULL)
{
  hash_set <tree> *visited = NULL;
  STRIP_NOPS (op);
  while (TREE_CODE (op) == SSA_NAME
	 && !SSA_NAME_IS_DEFAULT_DEF (op)
	 /* We might be called via fold_stmt during cfgcleanup where
	    SSA form need not be up-to-date.  */
	 && !name_registered_for_update_p (op) 
	 && (gimple_assign_single_p (SSA_NAME_DEF_STMT (op))
	     || gimple_code (SSA_NAME_DEF_STMT (op)) == GIMPLE_PHI))
    {
      if (global_visited)
	{
	  if (!*global_visited)
	    *global_visited = new hash_set<tree>;
	  if ((*global_visited)->add (op))
	    goto done;
	}	
      else
	{
	  if (!visited)
	    visited = new hash_set<tree>;
	  if (visited->add (op))
	    goto done;
	}
      /* Special case
	 if (ptr == 0)
	   ptr = 0;
	 else
	   ptr = ptr.foo;
	 This pattern is implicitly produced for casts to non-primary
	 bases.  When doing context analysis, we do not really care
	 about the case pointer is NULL, becuase the call will be
	 undefined anyway.  */
      if (gimple_code (SSA_NAME_DEF_STMT (op)) == GIMPLE_PHI)
	{
	  gimple *phi = SSA_NAME_DEF_STMT (op);

	  if (gimple_phi_num_args (phi) > 2)
	    goto done;
	  if (gimple_phi_num_args (phi) == 1)
	    op = gimple_phi_arg_def (phi, 0);
	  else if (integer_zerop (gimple_phi_arg_def (phi, 0)))
	    op = gimple_phi_arg_def (phi, 1);
	  else if (integer_zerop (gimple_phi_arg_def (phi, 1)))
	    op = gimple_phi_arg_def (phi, 0);
	  else
	    goto done;
	}
      else
	{
	  if (gimple_assign_load_p (SSA_NAME_DEF_STMT (op)))
	    goto done;
	  op = gimple_assign_rhs1 (SSA_NAME_DEF_STMT (op));
	}
      STRIP_NOPS (op);
    }
done:
  if (visited)
    delete (visited);
  return op;
}

/* Create polymorphic call context from IP invariant CST.
   This is typically &global_var.
   OTR_TYPE specify type of polymorphic call or NULL if unknown, OFF
   is offset of call.  */

ipa_polymorphic_call_context::ipa_polymorphic_call_context (tree cst,
							    tree otr_type,
							    HOST_WIDE_INT off)
{
  clear_speculation ();
  set_by_invariant (cst, otr_type, off);
}

/* Build context for pointer REF contained in FNDECL at statement STMT.
   if INSTANCE is non-NULL, return pointer to the object described by
   the context or DECL where context is contained in.  */

ipa_polymorphic_call_context::ipa_polymorphic_call_context (tree fndecl,
							    tree ref,
							    gimple *stmt,
							    tree *instance)
{
  tree otr_type = NULL;
  tree base_pointer;
  hash_set <tree> *visited = NULL;

  if (TREE_CODE (ref) == OBJ_TYPE_REF)
    {
      otr_type = obj_type_ref_class (ref);
      base_pointer = OBJ_TYPE_REF_OBJECT (ref);
    }
  else
    base_pointer = ref;

  /* Set up basic info in case we find nothing interesting in the analysis.  */
  clear_speculation ();
  clear_outer_type (otr_type);
  invalid = false;

  /* Walk SSA for outer object.  */
  while (true)
    {
      base_pointer = walk_ssa_copies (base_pointer, &visited);
      if (TREE_CODE (base_pointer) == ADDR_EXPR)
	{
	  HOST_WIDE_INT size, max_size;
	  HOST_WIDE_INT offset2;
	  bool reverse;
	  tree base
	    = get_ref_base_and_extent (TREE_OPERAND (base_pointer, 0),
				       &offset2, &size, &max_size, &reverse);

	  if (max_size != -1 && max_size == size)
	    combine_speculation_with (TYPE_MAIN_VARIANT (TREE_TYPE (base)),
				      offset + offset2,
				      true,
				      NULL /* Do not change outer type.  */);

	  /* If this is a varying address, punt.  */
	  if ((TREE_CODE (base) == MEM_REF || DECL_P (base))
	      && max_size != -1
	      && max_size == size)
	    {
	      /* We found dereference of a pointer.  Type of the pointer
		 and MEM_REF is meaningless, but we can look futher.  */
	      if (TREE_CODE (base) == MEM_REF)
		{
		  base_pointer = TREE_OPERAND (base, 0);
		  offset
		    += offset2 + mem_ref_offset (base).to_short_addr () * BITS_PER_UNIT;
		  outer_type = NULL;
		}
	      /* We found base object.  In this case the outer_type
		 is known.  */
	      else if (DECL_P (base))
		{
		  if (visited)
		    delete (visited);
		  /* Only type inconsistent programs can have otr_type that is
		     not part of outer type.  */
		  if (otr_type
		      && !contains_type_p (TREE_TYPE (base),
					   offset + offset2, otr_type))
		    {
		      invalid = true;
		      if (instance)
			*instance = base_pointer;
		      return;
		    }
		  set_by_decl (base, offset + offset2);
		  if (outer_type && maybe_in_construction && stmt)
		    maybe_in_construction
		     = decl_maybe_in_construction_p (base,
						     outer_type,
						     stmt,
						     fndecl);
		  if (instance)
		    *instance = base;
		  return;
		}
	      else
		break;
	    }
	  else
	    break;
	}
      else if (TREE_CODE (base_pointer) == POINTER_PLUS_EXPR
	       && tree_fits_uhwi_p (TREE_OPERAND (base_pointer, 1)))
	{
	  offset += tree_to_shwi (TREE_OPERAND (base_pointer, 1))
		    * BITS_PER_UNIT;
	  base_pointer = TREE_OPERAND (base_pointer, 0);
	}
      else
	break;
    }

  if (visited)
    delete (visited);

  /* Try to determine type of the outer object.  */
  if (TREE_CODE (base_pointer) == SSA_NAME
      && SSA_NAME_IS_DEFAULT_DEF (base_pointer)
      && TREE_CODE (SSA_NAME_VAR (base_pointer)) == PARM_DECL)
    {
      /* See if parameter is THIS pointer of a method.  */
      if (TREE_CODE (TREE_TYPE (fndecl)) == METHOD_TYPE
	  && SSA_NAME_VAR (base_pointer) == DECL_ARGUMENTS (fndecl))
	{
	  outer_type
	     = TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (base_pointer)));
	  gcc_assert (TREE_CODE (outer_type) == RECORD_TYPE
		      || TREE_CODE (outer_type) == UNION_TYPE);

	  /* Dynamic casting has possibly upcasted the type
	     in the hiearchy.  In this case outer type is less
	     informative than inner type and we should forget
	     about it.  */
	  if ((otr_type
	       && !contains_type_p (outer_type, offset,
				    otr_type))
	      || !contains_polymorphic_type_p (outer_type))
	    {
	      outer_type = NULL;
	      if (instance)
		*instance = base_pointer;
	      return;
	    }

	  dynamic = true;

	  /* If the function is constructor or destructor, then
	     the type is possibly in construction, but we know
	     it is not derived type.  */
	  if (DECL_CXX_CONSTRUCTOR_P (fndecl)
	      || DECL_CXX_DESTRUCTOR_P (fndecl))
	    {
	      maybe_in_construction = true;
	      maybe_derived_type = false;
	    }
	  else
	    {
	      maybe_derived_type = true;
	      maybe_in_construction = false;
	    }
	  if (instance)
	    *instance = base_pointer;
	  return;
	}
      /* Non-PODs passed by value are really passed by invisible
	 reference.  In this case we also know the type of the
	 object.  */
      if (DECL_BY_REFERENCE (SSA_NAME_VAR (base_pointer)))
	{
	  outer_type
	     = TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (base_pointer)));
	  /* Only type inconsistent programs can have otr_type that is
	     not part of outer type.  */
	  if (otr_type && !contains_type_p (outer_type, offset,
					    otr_type))
	    { 
	      invalid = true;
	      if (instance)
		*instance = base_pointer;
	      return;
	    }
	  /* Non-polymorphic types have no interest for us.  */
	  else if (!otr_type && !contains_polymorphic_type_p (outer_type))
	    {
	      outer_type = NULL;
	      if (instance)
		*instance = base_pointer;
	      return;
	    }
	  maybe_derived_type = false;
	  maybe_in_construction = false;
	  if (instance)
	    *instance = base_pointer;
	  return;
	}
    }

  tree base_type = TREE_TYPE (base_pointer);

  if (TREE_CODE (base_pointer) == SSA_NAME
      && SSA_NAME_IS_DEFAULT_DEF (base_pointer)
      && !(TREE_CODE (SSA_NAME_VAR (base_pointer)) == PARM_DECL
	   || TREE_CODE (SSA_NAME_VAR (base_pointer)) == RESULT_DECL))
    {
      invalid = true;
      if (instance)
	*instance = base_pointer;
      return;
    }
  if (TREE_CODE (base_pointer) == SSA_NAME
      && SSA_NAME_DEF_STMT (base_pointer)
      && gimple_assign_single_p (SSA_NAME_DEF_STMT (base_pointer)))
    base_type = TREE_TYPE (gimple_assign_rhs1
			    (SSA_NAME_DEF_STMT (base_pointer)));
 
  if (base_type && POINTER_TYPE_P (base_type))
    combine_speculation_with (TYPE_MAIN_VARIANT (TREE_TYPE (base_type)),
			      offset,
			      true, NULL /* Do not change type here */);
  /* TODO: There are multiple ways to derive a type.  For instance
     if BASE_POINTER is passed to an constructor call prior our refernece.
     We do not make this type of flow sensitive analysis yet.  */
  if (instance)
    *instance = base_pointer;
  return;
}

/* Structure to be passed in between detect_type_change and
   check_stmt_for_type_change.  */

struct type_change_info
{
  /* Offset into the object where there is the virtual method pointer we are
     looking for.  */
  HOST_WIDE_INT offset;
  /* The declaration or SSA_NAME pointer of the base that we are checking for
     type change.  */
  tree instance;
  /* The reference to virtual table pointer used.  */
  tree vtbl_ptr_ref;
  tree otr_type;
  /* If we actually can tell the type that the object has changed to, it is
     stored in this field.  Otherwise it remains NULL_TREE.  */
  tree known_current_type;
  HOST_WIDE_INT known_current_offset;

  /* Set to true if dynamic type change has been detected.  */
  bool type_maybe_changed;
  /* Set to true if multiple types have been encountered.  known_current_type
     must be disregarded in that case.  */
  bool multiple_types_encountered;
  /* Set to true if we possibly missed some dynamic type changes and we should
     consider the set to be speculative.  */
  bool speculative;
  bool seen_unanalyzed_store;
};

/* Return true if STMT is not call and can modify a virtual method table pointer.
   We take advantage of fact that vtable stores must appear within constructor
   and destructor functions.  */

static bool
noncall_stmt_may_be_vtbl_ptr_store (gimple *stmt)
{
  if (is_gimple_assign (stmt))
    {
      tree lhs = gimple_assign_lhs (stmt);

      if (gimple_clobber_p (stmt))
	return false;
      if (!AGGREGATE_TYPE_P (TREE_TYPE (lhs)))
	{
	  if (flag_strict_aliasing
	      && !POINTER_TYPE_P (TREE_TYPE (lhs)))
	    return false;

	  if (TREE_CODE (lhs) == COMPONENT_REF
	      && !DECL_VIRTUAL_P (TREE_OPERAND (lhs, 1)))
	    return false;
	  /* In the future we might want to use get_base_ref_and_offset to find
	     if there is a field corresponding to the offset and if so, proceed
	     almost like if it was a component ref.  */
	}
    }

  /* Code unification may mess with inline stacks.  */
  if (cfun->after_inlining)
    return true;

  /* Walk the inline stack and watch out for ctors/dtors.
     TODO: Maybe we can require the store to appear in toplevel
     block of CTOR/DTOR.  */
  for (tree block = gimple_block (stmt); block && TREE_CODE (block) == BLOCK;
       block = BLOCK_SUPERCONTEXT (block))
    if (BLOCK_ABSTRACT_ORIGIN (block)
	&& TREE_CODE (BLOCK_ABSTRACT_ORIGIN (block)) == FUNCTION_DECL)
      return inlined_polymorphic_ctor_dtor_block_p (block, false);
  return (TREE_CODE (TREE_TYPE (current_function_decl)) == METHOD_TYPE
	  && (DECL_CXX_CONSTRUCTOR_P (current_function_decl)
	      || DECL_CXX_DESTRUCTOR_P (current_function_decl)));
}

/* If STMT can be proved to be an assignment to the virtual method table
   pointer of ANALYZED_OBJ and the type associated with the new table
   identified, return the type.  Otherwise return NULL_TREE if type changes
   in unknown way or ERROR_MARK_NODE if type is unchanged.  */

static tree
extr_type_from_vtbl_ptr_store (gimple *stmt, struct type_change_info *tci,
			       HOST_WIDE_INT *type_offset)
{
  HOST_WIDE_INT offset, size, max_size;
  tree lhs, rhs, base;
  bool reverse;

  if (!gimple_assign_single_p (stmt))
    return NULL_TREE;

  lhs = gimple_assign_lhs (stmt);
  rhs = gimple_assign_rhs1 (stmt);
  if (TREE_CODE (lhs) != COMPONENT_REF
      || !DECL_VIRTUAL_P (TREE_OPERAND (lhs, 1)))
     {
	if (dump_file)
	  fprintf (dump_file, "  LHS is not virtual table.\n");
	return NULL_TREE;
     }

  if (tci->vtbl_ptr_ref && operand_equal_p (lhs, tci->vtbl_ptr_ref, 0))
    ;
  else
    {
      base = get_ref_base_and_extent (lhs, &offset, &size, &max_size, &reverse);
      if (DECL_P (tci->instance))
	{
	  if (base != tci->instance)
	    {
	      if (dump_file)
		{
		  fprintf (dump_file, "    base:");
		  print_generic_expr (dump_file, base, TDF_SLIM);
		  fprintf (dump_file, " does not match instance:");
		  print_generic_expr (dump_file, tci->instance, TDF_SLIM);
		  fprintf (dump_file, "\n");
		}
	      return NULL_TREE;
	    }
	}
      else if (TREE_CODE (base) == MEM_REF)
	{
	  if (!operand_equal_p (tci->instance, TREE_OPERAND (base, 0), 0))
	    {
	      if (dump_file)
		{
		  fprintf (dump_file, "    base mem ref:");
		  print_generic_expr (dump_file, base, TDF_SLIM);
		  fprintf (dump_file, " does not match instance:");
		  print_generic_expr (dump_file, tci->instance, TDF_SLIM);
		  fprintf (dump_file, "\n");
		}
	      return NULL_TREE;
	    }
	  if (!integer_zerop (TREE_OPERAND (base, 1)))
	    {
	      if (!tree_fits_shwi_p (TREE_OPERAND (base, 1)))
		{
		  if (dump_file)
		    {
		      fprintf (dump_file, "    base mem ref:");
		      print_generic_expr (dump_file, base, TDF_SLIM);
		      fprintf (dump_file, " has non-representable offset:");
		      print_generic_expr (dump_file, tci->instance, TDF_SLIM);
		      fprintf (dump_file, "\n");
		    }
		  return NULL_TREE;
		}
	      else
	        offset += tree_to_shwi (TREE_OPERAND (base, 1)) * BITS_PER_UNIT;
	    }
	}
      else if (!operand_equal_p (tci->instance, base, 0)
	       || tci->offset)
	{
	  if (dump_file)
	    {
	      fprintf (dump_file, "    base:");
	      print_generic_expr (dump_file, base, TDF_SLIM);
	      fprintf (dump_file, " does not match instance:");
	      print_generic_expr (dump_file, tci->instance, TDF_SLIM);
	      fprintf (dump_file, " with offset %i\n", (int)tci->offset);
	    }
	  return tci->offset > POINTER_SIZE ? error_mark_node : NULL_TREE;
	}
      if (offset != tci->offset
	  || size != POINTER_SIZE
	  || max_size != POINTER_SIZE)
	{
	  if (dump_file)
	    fprintf (dump_file, "    wrong offset %i!=%i or size %i\n",
		     (int)offset, (int)tci->offset, (int)size);
	  return offset + POINTER_SIZE <= tci->offset
	         || (max_size != -1
		     && tci->offset + POINTER_SIZE > offset + max_size)
		 ? error_mark_node : NULL;
	}
    }

  tree vtable;
  unsigned HOST_WIDE_INT offset2;

  if (!vtable_pointer_value_to_vtable (rhs, &vtable, &offset2))
    {
      if (dump_file)
	fprintf (dump_file, "    Failed to lookup binfo\n");
      return NULL;
    }

  tree binfo = subbinfo_with_vtable_at_offset (TYPE_BINFO (DECL_CONTEXT (vtable)),
					       offset2, vtable);
  if (!binfo)
    {
      if (dump_file)
	fprintf (dump_file, "    Construction vtable used\n");
      /* FIXME: We should suport construction contexts.  */
      return NULL;
    }
 
  *type_offset = tree_to_shwi (BINFO_OFFSET (binfo)) * BITS_PER_UNIT;
  return DECL_CONTEXT (vtable);
}

/* Record dynamic type change of TCI to TYPE.  */

static void
record_known_type (struct type_change_info *tci, tree type, HOST_WIDE_INT offset)
{
  if (dump_file)
    {
      if (type)
	{
          fprintf (dump_file, "  Recording type: ");
	  print_generic_expr (dump_file, type, TDF_SLIM);
          fprintf (dump_file, " at offset %i\n", (int)offset);
	}
     else
       fprintf (dump_file, "  Recording unknown type\n");
    }

  /* If we found a constructor of type that is not polymorphic or
     that may contain the type in question as a field (not as base),
     restrict to the inner class first to make type matching bellow
     happier.  */
  if (type
      && (offset
          || (TREE_CODE (type) != RECORD_TYPE
	      || !TYPE_BINFO (type)
	      || !polymorphic_type_binfo_p (TYPE_BINFO (type)))))
    {
      ipa_polymorphic_call_context context;

      context.offset = offset;
      context.outer_type = type;
      context.maybe_in_construction = false;
      context.maybe_derived_type = false;
      context.dynamic = true;
      /* If we failed to find the inner type, we know that the call
	 would be undefined for type produced here.  */
      if (!context.restrict_to_inner_class (tci->otr_type))
	{
	  if (dump_file)
	    fprintf (dump_file, "  Ignoring; does not contain otr_type\n");
	  return;
	}
      /* Watch for case we reached an POD type and anticipate placement
	 new.  */
      if (!context.maybe_derived_type)
	{
          type = context.outer_type;
          offset = context.offset;
	}
    }
  if (tci->type_maybe_changed
      && (!types_same_for_odr (type, tci->known_current_type)
	  || offset != tci->known_current_offset))
    tci->multiple_types_encountered = true;
  tci->known_current_type = TYPE_MAIN_VARIANT (type);
  tci->known_current_offset = offset;
  tci->type_maybe_changed = true;
}

/* Callback of walk_aliased_vdefs and a helper function for
   detect_type_change to check whether a particular statement may modify
   the virtual table pointer, and if possible also determine the new type of
   the (sub-)object.  It stores its result into DATA, which points to a
   type_change_info structure.  */

static bool
check_stmt_for_type_change (ao_ref *ao ATTRIBUTE_UNUSED, tree vdef, void *data)
{
  gimple *stmt = SSA_NAME_DEF_STMT (vdef);
  struct type_change_info *tci = (struct type_change_info *) data;
  tree fn;

  /* If we already gave up, just terminate the rest of walk.  */
  if (tci->multiple_types_encountered)
    return true;

  if (is_gimple_call (stmt))
    {
      if (gimple_call_flags (stmt) & (ECF_CONST | ECF_PURE))
	return false;

      /* Check for a constructor call.  */
      if ((fn = gimple_call_fndecl (stmt)) != NULL_TREE
	  && DECL_CXX_CONSTRUCTOR_P (fn)
	  && TREE_CODE (TREE_TYPE (fn)) == METHOD_TYPE
	  && gimple_call_num_args (stmt))
      {
	tree op = walk_ssa_copies (gimple_call_arg (stmt, 0));
	tree type = TYPE_METHOD_BASETYPE (TREE_TYPE (fn));
	HOST_WIDE_INT offset = 0, size, max_size;
	bool reverse;

	if (dump_file)
	  {
	    fprintf (dump_file, "  Checking constructor call: ");
	    print_gimple_stmt (dump_file, stmt, 0, 0);
	  }

	/* See if THIS parameter seems like instance pointer.  */
	if (TREE_CODE (op) == ADDR_EXPR)
	  {
	    op = get_ref_base_and_extent (TREE_OPERAND (op, 0), &offset,
					  &size, &max_size, &reverse);
	    if (size != max_size || max_size == -1)
	      {
                tci->speculative = true;
	        return false;
	      }
	    if (op && TREE_CODE (op) == MEM_REF)
	      {
		if (!tree_fits_shwi_p (TREE_OPERAND (op, 1)))
		  {
                    tci->speculative = true;
		    return false;
		  }
		offset += tree_to_shwi (TREE_OPERAND (op, 1))
			  * BITS_PER_UNIT;
		op = TREE_OPERAND (op, 0);
	      }
	    else if (DECL_P (op))
	      ;
	    else
	      {
                tci->speculative = true;
	        return false;
	      }
	    op = walk_ssa_copies (op);
	  }
	if (operand_equal_p (op, tci->instance, 0)
	    && TYPE_SIZE (type)
	    && TREE_CODE (TYPE_SIZE (type)) == INTEGER_CST
	    && tree_fits_shwi_p (TYPE_SIZE (type))
	    && tree_to_shwi (TYPE_SIZE (type)) + offset > tci->offset
	    /* Some inlined constructors may look as follows:
		  _3 = operator new (16);
		  MEM[(struct  &)_3] ={v} {CLOBBER};
		  MEM[(struct CompositeClass *)_3]._vptr.CompositeClass
		    = &MEM[(void *)&_ZTV14CompositeClass + 16B];
		  _7 = &MEM[(struct CompositeClass *)_3].object;
		  EmptyClass::EmptyClass (_7);

	       When determining dynamic type of _3 and because we stop at first
	       dynamic type found, we would stop on EmptyClass::EmptyClass (_7).
	       In this case the emptyclass is not even polymorphic and we miss
	       it is contained in an outer type that is polymorphic.  */

	    && (tci->offset == offset || contains_polymorphic_type_p (type)))
	  {
	    record_known_type (tci, type, tci->offset - offset);
	    return true;
	  }
      }
     /* Calls may possibly change dynamic type by placement new. Assume
        it will not happen, but make result speculative only.  */
     if (dump_file)
	{
          fprintf (dump_file, "  Function call may change dynamic type:");
	  print_gimple_stmt (dump_file, stmt, 0, 0);
	}
     tci->speculative = true;
     return false;
   }
  /* Check for inlined virtual table store.  */
  else if (noncall_stmt_may_be_vtbl_ptr_store (stmt))
    {
      tree type;
      HOST_WIDE_INT offset = 0;
      if (dump_file)
	{
	  fprintf (dump_file, "  Checking vtbl store: ");
	  print_gimple_stmt (dump_file, stmt, 0, 0);
	}

      type = extr_type_from_vtbl_ptr_store (stmt, tci, &offset);
      if (type == error_mark_node)
	return false;
      gcc_assert (!type || TYPE_MAIN_VARIANT (type) == type);
      if (!type)
	{
	  if (dump_file)
	    fprintf (dump_file, "  Unanalyzed store may change type.\n");
	  tci->seen_unanalyzed_store = true;
	  tci->speculative = true;
	}
      else
        record_known_type (tci, type, offset);
      return true;
    }
  else
    return false;
}

/* THIS is polymorphic call context obtained from get_polymorphic_context.
   OTR_OBJECT is pointer to the instance returned by OBJ_TYPE_REF_OBJECT.
   INSTANCE is pointer to the outer instance as returned by
   get_polymorphic_context.  To avoid creation of temporary expressions,
   INSTANCE may also be an declaration of get_polymorphic_context found the
   value to be in static storage.

   If the type of instance is not fully determined
   (either OUTER_TYPE is unknown or MAYBE_IN_CONSTRUCTION/INCLUDE_DERIVED_TYPES
   is set), try to walk memory writes and find the actual construction of the
   instance.

   Return true if memory is unchanged from function entry.

   We do not include this analysis in the context analysis itself, because
   it needs memory SSA to be fully built and the walk may be expensive.
   So it is not suitable for use withing fold_stmt and similar uses.  */

bool
ipa_polymorphic_call_context::get_dynamic_type (tree instance,
						tree otr_object,
						tree otr_type,
						gimple *call)
{
  struct type_change_info tci;
  ao_ref ao;
  bool function_entry_reached = false;
  tree instance_ref = NULL;
  gimple *stmt = call;
  /* Remember OFFSET before it is modified by restrict_to_inner_class.
     This is because we do not update INSTANCE when walking inwards.  */
  HOST_WIDE_INT instance_offset = offset;
  tree instance_outer_type = outer_type;

  if (otr_type)
    otr_type = TYPE_MAIN_VARIANT (otr_type);

  /* Walk into inner type. This may clear maybe_derived_type and save us
     from useless work.  It also makes later comparsions with static type
     easier.  */
  if (outer_type && otr_type)
    {
      if (!restrict_to_inner_class (otr_type))
        return false;
    }

  if (!maybe_in_construction && !maybe_derived_type)
    return false;

  /* We need to obtain refernce to virtual table pointer.  It is better
     to look it up in the code rather than build our own.  This require bit
     of pattern matching, but we end up verifying that what we found is
     correct. 

     What we pattern match is:

       tmp = instance->_vptr.A;   // vtbl ptr load
       tmp2 = tmp[otr_token];	  // vtable lookup
       OBJ_TYPE_REF(tmp2;instance->0) (instance);
 
     We want to start alias oracle walk from vtbl pointer load,
     but we may not be able to identify it, for example, when PRE moved the
     load around.  */

  if (gimple_code (call) == GIMPLE_CALL)
    {
      tree ref = gimple_call_fn (call);
      HOST_WIDE_INT offset2, size, max_size;
      bool reverse;

      if (TREE_CODE (ref) == OBJ_TYPE_REF)
	{
	  ref = OBJ_TYPE_REF_EXPR (ref);
	  ref = walk_ssa_copies (ref);

	  /* If call target is already known, no need to do the expensive
 	     memory walk.  */
	  if (is_gimple_min_invariant (ref))
	    return false;

	  /* Check if definition looks like vtable lookup.  */
	  if (TREE_CODE (ref) == SSA_NAME
	      && !SSA_NAME_IS_DEFAULT_DEF (ref)
	      && gimple_assign_load_p (SSA_NAME_DEF_STMT (ref))
	      && TREE_CODE (gimple_assign_rhs1
			     (SSA_NAME_DEF_STMT (ref))) == MEM_REF)
	    {
	      ref = get_base_address
		     (TREE_OPERAND (gimple_assign_rhs1
				     (SSA_NAME_DEF_STMT (ref)), 0));
	      ref = walk_ssa_copies (ref);
	      /* Find base address of the lookup and see if it looks like
		 vptr load.  */
	      if (TREE_CODE (ref) == SSA_NAME
		  && !SSA_NAME_IS_DEFAULT_DEF (ref)
		  && gimple_assign_load_p (SSA_NAME_DEF_STMT (ref)))
		{
		  tree ref_exp = gimple_assign_rhs1 (SSA_NAME_DEF_STMT (ref));
		  tree base_ref
		    = get_ref_base_and_extent (ref_exp, &offset2, &size,
					       &max_size, &reverse);

		  /* Finally verify that what we found looks like read from
		     OTR_OBJECT or from INSTANCE with offset OFFSET.  */
		  if (base_ref
		      && ((TREE_CODE (base_ref) == MEM_REF
		           && ((offset2 == instance_offset
		                && TREE_OPERAND (base_ref, 0) == instance)
			       || (!offset2
				   && TREE_OPERAND (base_ref, 0)
				      == otr_object)))
			  || (DECL_P (instance) && base_ref == instance
			      && offset2 == instance_offset)))
		    {
		      stmt = SSA_NAME_DEF_STMT (ref);
		      instance_ref = ref_exp;
		    }
		}
	    }
	}
    }
 
  /* If we failed to look up the reference in code, build our own.  */
  if (!instance_ref)
    {
      /* If the statement in question does not use memory, we can't tell
	 anything.  */
      if (!gimple_vuse (stmt))
	return false;
      ao_ref_init_from_ptr_and_size (&ao, otr_object, NULL);
    }
  else
  /* Otherwise use the real reference.  */
    ao_ref_init (&ao, instance_ref);

  /* We look for vtbl pointer read.  */
  ao.size = POINTER_SIZE;
  ao.max_size = ao.size;
  /* We are looking for stores to vptr pointer within the instance of
     outer type.
     TODO: The vptr pointer type is globally known, we probably should
     keep it and do that even when otr_type is unknown.  */
  if (otr_type)
    {
      ao.base_alias_set
	= get_alias_set (outer_type ? outer_type : otr_type);
      ao.ref_alias_set
        = get_alias_set (TREE_TYPE (BINFO_VTABLE (TYPE_BINFO (otr_type))));
    }

  if (dump_file)
    {
      fprintf (dump_file, "Determining dynamic type for call: ");
      print_gimple_stmt (dump_file, call, 0, 0);
      fprintf (dump_file, "  Starting walk at: ");
      print_gimple_stmt (dump_file, stmt, 0, 0);
      fprintf (dump_file, "  instance pointer: ");
      print_generic_expr (dump_file, otr_object, TDF_SLIM);
      fprintf (dump_file, "  Outer instance pointer: ");
      print_generic_expr (dump_file, instance, TDF_SLIM);
      fprintf (dump_file, " offset: %i (bits)", (int)instance_offset);
      fprintf (dump_file, " vtbl reference: ");
      print_generic_expr (dump_file, instance_ref, TDF_SLIM);
      fprintf (dump_file, "\n");
    }

  tci.offset = instance_offset;
  tci.instance = instance;
  tci.vtbl_ptr_ref = instance_ref;
  gcc_assert (TREE_CODE (instance) != MEM_REF);
  tci.known_current_type = NULL_TREE;
  tci.known_current_offset = 0;
  tci.otr_type = otr_type;
  tci.type_maybe_changed = false;
  tci.multiple_types_encountered = false;
  tci.speculative = false;
  tci.seen_unanalyzed_store = false;

  walk_aliased_vdefs (&ao, gimple_vuse (stmt), check_stmt_for_type_change,
		      &tci, NULL, &function_entry_reached);

  /* If we did not find any type changing statements, we may still drop
     maybe_in_construction flag if the context already have outer type. 

     Here we make special assumptions about both constructors and
     destructors which are all the functions that are allowed to alter the
     VMT pointers.  It assumes that destructors begin with assignment into
     all VMT pointers and that constructors essentially look in the
     following way:

     1) The very first thing they do is that they call constructors of
     ancestor sub-objects that have them.

     2) Then VMT pointers of this and all its ancestors is set to new
     values corresponding to the type corresponding to the constructor.

     3) Only afterwards, other stuff such as constructor of member
     sub-objects and the code written by the user is run.  Only this may
     include calling virtual functions, directly or indirectly.

     4) placement new can not be used to change type of non-POD statically
     allocated variables.

     There is no way to call a constructor of an ancestor sub-object in any
     other way.

     This means that we do not have to care whether constructors get the
     correct type information because they will always change it (in fact,
     if we define the type to be given by the VMT pointer, it is undefined).

     The most important fact to derive from the above is that if, for some
     statement in the section 3, we try to detect whether the dynamic type
     has changed, we can safely ignore all calls as we examine the function
     body backwards until we reach statements in section 2 because these
     calls cannot be ancestor constructors or destructors (if the input is
     not bogus) and so do not change the dynamic type (this holds true only
     for automatically allocated objects but at the moment we devirtualize
     only these).  We then must detect that statements in section 2 change
     the dynamic type and can try to derive the new type.  That is enough
     and we can stop, we will never see the calls into constructors of
     sub-objects in this code. 

     Therefore if the static outer type was found (outer_type)
     we can safely ignore tci.speculative that is set on calls and give up
     only if there was dyanmic type store that may affect given variable
     (seen_unanalyzed_store)  */

  if (!tci.type_maybe_changed
      || (outer_type
	  && !dynamic
	  && !tci.seen_unanalyzed_store
	  && !tci.multiple_types_encountered
	  && ((offset == tci.offset
	       && types_same_for_odr (tci.known_current_type,
				      outer_type))
	       || (instance_offset == offset
		   && types_same_for_odr (tci.known_current_type,
					  instance_outer_type)))))
    {
      if (!outer_type || tci.seen_unanalyzed_store)
	return false;
      if (maybe_in_construction)
        maybe_in_construction = false;
      if (dump_file)
	fprintf (dump_file, "  No dynamic type change found.\n");
      return true;
    }

  if (tci.known_current_type
      && !function_entry_reached
      && !tci.multiple_types_encountered)
    {
      if (!tci.speculative)
	{
	  outer_type = TYPE_MAIN_VARIANT (tci.known_current_type);
	  offset = tci.known_current_offset;
	  dynamic = true;
	  maybe_in_construction = false;
	  maybe_derived_type = false;
	  if (dump_file)
	    fprintf (dump_file, "  Determined dynamic type.\n");
	}
      else if (!speculative_outer_type
	       || speculative_maybe_derived_type)
	{
	  speculative_outer_type = TYPE_MAIN_VARIANT (tci.known_current_type);
	  speculative_offset = tci.known_current_offset;
	  speculative_maybe_derived_type = false;
	  if (dump_file)
	    fprintf (dump_file, "  Determined speculative dynamic type.\n");
	}
    }
  else if (dump_file)
    {
      fprintf (dump_file, "  Found multiple types%s%s\n",
	       function_entry_reached ? " (function entry reached)" : "",
	       function_entry_reached ? " (multiple types encountered)" : "");
    }

  return false;
}

/* See if speculation given by SPEC_OUTER_TYPE, SPEC_OFFSET and SPEC_MAYBE_DERIVED_TYPE
   seems consistent (and useful) with what we already have in the non-speculative context.  */

bool
ipa_polymorphic_call_context::speculation_consistent_p (tree spec_outer_type,
							HOST_WIDE_INT spec_offset,
							bool spec_maybe_derived_type,
							tree otr_type) const
{
  if (!flag_devirtualize_speculatively)
    return false;

  /* Non-polymorphic types are useless for deriving likely polymorphic
     call targets.  */
  if (!spec_outer_type || !contains_polymorphic_type_p (spec_outer_type))
    return false;

  /* If we know nothing, speculation is always good.  */
  if (!outer_type)
    return true;

  /* Speculation is only useful to avoid derived types.
     This is not 100% true for placement new, where the outer context may
     turn out to be useless, but ignore these for now.  */
  if (!maybe_derived_type)
    return false;

  /* If types agrees, speculation is consistent, but it makes sense only
     when it says something new.  */
  if (types_must_be_same_for_odr (spec_outer_type, outer_type))
    return maybe_derived_type && !spec_maybe_derived_type;

  /* If speculation does not contain the type in question, ignore it.  */
  if (otr_type
      && !contains_type_p (spec_outer_type, spec_offset, otr_type, false, true))
    return false;

  /* If outer type already contains speculation as a filed,
     it is useless.  We already know from OUTER_TYPE 
     SPEC_TYPE and that it is not in the construction.  */
  if (contains_type_p (outer_type, offset - spec_offset,
		       spec_outer_type, false, false))
    return false;

  /* If speculative outer type is not more specified than outer
     type, just give up. 
     We can only decide this safely if we can compare types with OUTER_TYPE.
   */
  if ((!in_lto_p || odr_type_p (outer_type))
      && !contains_type_p (spec_outer_type,
			   spec_offset - offset,
			   outer_type, false))
    return false;
  return true;
}

/* Improve THIS with speculation described by NEW_OUTER_TYPE, NEW_OFFSET,
   NEW_MAYBE_DERIVED_TYPE 
   If OTR_TYPE is set, assume the context is used with OTR_TYPE.  */

bool
ipa_polymorphic_call_context::combine_speculation_with
   (tree new_outer_type, HOST_WIDE_INT new_offset, bool new_maybe_derived_type,
    tree otr_type)
{
  if (!new_outer_type)
    return false;

  /* restrict_to_inner_class may eliminate wrong speculation making our job
     easeier.  */
  if (otr_type)
    restrict_to_inner_class (otr_type);

  if (!speculation_consistent_p (new_outer_type, new_offset,
				 new_maybe_derived_type, otr_type))
    return false;

  /* New speculation is a win in case we have no speculation or new
     speculation does not consider derivations.  */
  if (!speculative_outer_type
      || (speculative_maybe_derived_type
	  && !new_maybe_derived_type))
    {
      speculative_outer_type = new_outer_type;
      speculative_offset = new_offset;
      speculative_maybe_derived_type = new_maybe_derived_type;
      return true;
    }
  else if (types_must_be_same_for_odr (speculative_outer_type,
				       new_outer_type))
    {
      if (speculative_offset != new_offset)
	{
	  /* OK we have two contexts that seems valid but they disagree,
	     just give up.

	     This is not a lattice operation, so we may want to drop it later.  */
	  if (dump_file && (dump_flags & TDF_DETAILS))
	    fprintf (dump_file,
		     "Speculative outer types match, "
		     "offset mismatch -> invalid speculation\n");
	  clear_speculation ();
	  return true;
	}
      else
	{
	  if (speculative_maybe_derived_type && !new_maybe_derived_type)
	    {
	      speculative_maybe_derived_type = false;
	      return true;
	    }
	  else
	    return false;
	}
    }
  /* Choose type that contains the other.  This one either contains the outer
     as a field (thus giving exactly one target) or is deeper in the type
     hiearchy.  */
  else if (speculative_outer_type
	   && speculative_maybe_derived_type
	   && (new_offset > speculative_offset
	       || (new_offset == speculative_offset
		   && contains_type_p (new_outer_type,
				       0, speculative_outer_type, false))))
    {
      tree old_outer_type = speculative_outer_type;
      HOST_WIDE_INT old_offset = speculative_offset;
      bool old_maybe_derived_type = speculative_maybe_derived_type;

      speculative_outer_type = new_outer_type;
      speculative_offset = new_offset;
      speculative_maybe_derived_type = new_maybe_derived_type;

      if (otr_type)
	restrict_to_inner_class (otr_type);

      /* If the speculation turned out to make no sense, revert to sensible
	 one.  */
      if (!speculative_outer_type)
	{
	  speculative_outer_type = old_outer_type;
	  speculative_offset = old_offset;
	  speculative_maybe_derived_type = old_maybe_derived_type;
	  return false;
	}
      return (old_offset != speculative_offset
	      || old_maybe_derived_type != speculative_maybe_derived_type
	      || types_must_be_same_for_odr (speculative_outer_type,
					     new_outer_type));
    }
  return false;
}

/* Make speculation less specific so
   NEW_OUTER_TYPE, NEW_OFFSET, NEW_MAYBE_DERIVED_TYPE is also included.
   If OTR_TYPE is set, assume the context is used with OTR_TYPE.  */

bool
ipa_polymorphic_call_context::meet_speculation_with
   (tree new_outer_type, HOST_WIDE_INT new_offset, bool new_maybe_derived_type,
    tree otr_type)
{
  if (!new_outer_type && speculative_outer_type)
    {
      clear_speculation ();
      return true;
    }

  /* restrict_to_inner_class may eliminate wrong speculation making our job
     easeier.  */
  if (otr_type)
    restrict_to_inner_class (otr_type);

  if (!speculative_outer_type
      || !speculation_consistent_p (speculative_outer_type,
				    speculative_offset,
				    speculative_maybe_derived_type,
				    otr_type))
    return false;

  if (!speculation_consistent_p (new_outer_type, new_offset,
				 new_maybe_derived_type, otr_type))
    {
      clear_speculation ();
      return true;
    }

  else if (types_must_be_same_for_odr (speculative_outer_type,
				       new_outer_type))
    {
      if (speculative_offset != new_offset)
	{
	  clear_speculation ();
	  return true;
	}
      else
	{
	  if (!speculative_maybe_derived_type && new_maybe_derived_type)
	    {
	      speculative_maybe_derived_type = true;
	      return true;
	    }
	  else
	    return false;
	}
    }
  /* See if one type contains the other as a field (not base).  */
  else if (contains_type_p (new_outer_type, new_offset - speculative_offset,
			    speculative_outer_type, false, false))
    return false;
  else if (contains_type_p (speculative_outer_type,
			    speculative_offset - new_offset,
			    new_outer_type, false, false))
    {
      speculative_outer_type = new_outer_type;
      speculative_offset = new_offset;
      speculative_maybe_derived_type = new_maybe_derived_type;
      return true;
    }
  /* See if OUTER_TYPE is base of CTX.OUTER_TYPE.  */
  else if (contains_type_p (new_outer_type,
			    new_offset - speculative_offset,
			    speculative_outer_type, false, true))
    {
      if (!speculative_maybe_derived_type)
	{
	  speculative_maybe_derived_type = true;
	  return true;
	}
      return false;
    }
  /* See if CTX.OUTER_TYPE is base of OUTER_TYPE.  */
  else if (contains_type_p (speculative_outer_type,
			    speculative_offset - new_offset, new_outer_type, false, true))
    {
      speculative_outer_type = new_outer_type;
      speculative_offset = new_offset;
      speculative_maybe_derived_type = true;
      return true;
    }
  else
    {
      if (dump_file && (dump_flags & TDF_DETAILS))
        fprintf (dump_file, "Giving up on speculative meet\n");
      clear_speculation ();
      return true;
    }
}

/* Assume that both THIS and a given context is valid and strenghten THIS
   if possible.  Return true if any strenghtening was made.
   If actual type the context is being used in is known, OTR_TYPE should be
   set accordingly. This improves quality of combined result.  */

bool
ipa_polymorphic_call_context::combine_with (ipa_polymorphic_call_context ctx,
					    tree otr_type)
{
  bool updated = false;

  if (ctx.useless_p () || invalid)
    return false;

  /* Restricting context to inner type makes merging easier, however do not
     do that unless we know how the context is used (OTR_TYPE is non-NULL)  */
  if (otr_type && !invalid && !ctx.invalid)
    {
      restrict_to_inner_class (otr_type);
      ctx.restrict_to_inner_class (otr_type);
      if(invalid)
        return false;
    }

  if (dump_file && (dump_flags & TDF_DETAILS))
    {
      fprintf (dump_file, "Polymorphic call context combine:");
      dump (dump_file);
      fprintf (dump_file, "With context:                    ");
      ctx.dump (dump_file);
      if (otr_type)
	{
          fprintf (dump_file, "To be used with type:            ");
	  print_generic_expr (dump_file, otr_type, TDF_SLIM);
          fprintf (dump_file, "\n");
	}
    }

  /* If call is known to be invalid, we are done.  */
  if (ctx.invalid)
    {
      if (dump_file && (dump_flags & TDF_DETAILS))
        fprintf (dump_file, "-> Invalid context\n");
      goto invalidate;
    }

  if (!ctx.outer_type)
    ;
  else if (!outer_type)
    {
      outer_type = ctx.outer_type;
      offset = ctx.offset;
      dynamic = ctx.dynamic;
      maybe_in_construction = ctx.maybe_in_construction;
      maybe_derived_type = ctx.maybe_derived_type;
      updated = true;
    }
  /* If types are known to be same, merging is quite easy.  */
  else if (types_must_be_same_for_odr (outer_type, ctx.outer_type))
    {
      if (offset != ctx.offset
	  && TYPE_SIZE (outer_type)
	  && TREE_CODE (TYPE_SIZE (outer_type)) == INTEGER_CST)
	{
	  if (dump_file && (dump_flags & TDF_DETAILS))
	    fprintf (dump_file, "Outer types match, offset mismatch -> invalid\n");
	  clear_speculation ();
	  clear_outer_type ();
	  invalid = true;
	  return true;
	}
      if (dump_file && (dump_flags & TDF_DETAILS))
        fprintf (dump_file, "Outer types match, merging flags\n");
      if (maybe_in_construction && !ctx.maybe_in_construction)
	{
	  updated = true;
	  maybe_in_construction = false;
	}
      if (maybe_derived_type && !ctx.maybe_derived_type)
	{
	  updated = true;
	  maybe_derived_type = false;
	}
      if (dynamic && !ctx.dynamic)
	{
	  updated = true;
	  dynamic = false;
	}
    }
  /* If we know the type precisely, there is not much to improve.  */
  else if (!maybe_derived_type && !maybe_in_construction
	   && !ctx.maybe_derived_type && !ctx.maybe_in_construction)
    {
      /* It may be easy to check if second context permits the first
	 and set INVALID otherwise.  This is not easy to do in general;
	 contains_type_p may return false negatives for non-comparable
	 types.  

	 If OTR_TYPE is known, we however can expect that
	 restrict_to_inner_class should have discovered the same base
	 type.  */
      if (otr_type && !ctx.maybe_in_construction && !ctx.maybe_derived_type)
	{
	  if (dump_file && (dump_flags & TDF_DETAILS))
	    fprintf (dump_file, "Contextes disagree -> invalid\n");
	  goto invalidate;
	}
    }
  /* See if one type contains the other as a field (not base).
     In this case we want to choose the wider type, because it contains
     more information.  */
  else if (contains_type_p (ctx.outer_type, ctx.offset - offset,
			    outer_type, false, false))
    {
      if (dump_file && (dump_flags & TDF_DETAILS))
	fprintf (dump_file, "Second type contain the first as a field\n");

      if (maybe_derived_type)
	{
	  outer_type = ctx.outer_type;
	  maybe_derived_type = ctx.maybe_derived_type;
	  offset = ctx.offset;
	  dynamic = ctx.dynamic;
	  updated = true;
	}

      /* If we do not know how the context is being used, we can
	 not clear MAYBE_IN_CONSTRUCTION because it may be offseted
	 to other component of OUTER_TYPE later and we know nothing
	 about it.  */
      if (otr_type && maybe_in_construction
	  && !ctx.maybe_in_construction)
	{
          maybe_in_construction = false;
	  updated = true;
	}
    }
  else if (contains_type_p (outer_type, offset - ctx.offset,
			    ctx.outer_type, false, false))
    {
      if (dump_file && (dump_flags & TDF_DETAILS))
	fprintf (dump_file, "First type contain the second as a field\n");

      if (otr_type && maybe_in_construction
	  && !ctx.maybe_in_construction)
	{
          maybe_in_construction = false;
	  updated = true;
	}
    }
  /* See if OUTER_TYPE is base of CTX.OUTER_TYPE.  */
  else if (contains_type_p (ctx.outer_type,
			    ctx.offset - offset, outer_type, false, true))
    {
      if (dump_file && (dump_flags & TDF_DETAILS))
	fprintf (dump_file, "First type is base of second\n");
      if (!maybe_derived_type)
	{
	  if (!ctx.maybe_in_construction
	      && types_odr_comparable (outer_type, ctx.outer_type))
	    {
	      if (dump_file && (dump_flags & TDF_DETAILS))
		fprintf (dump_file, "Second context does not permit base -> invalid\n");
	      goto invalidate;
	    }
	}
      /* Pick variant deeper in the hiearchy.  */
      else
	{
	  outer_type = ctx.outer_type;
	  maybe_in_construction = ctx.maybe_in_construction;
	  maybe_derived_type = ctx.maybe_derived_type;
	  offset = ctx.offset;
	  dynamic = ctx.dynamic;
          updated = true;
	}
    }
  /* See if CTX.OUTER_TYPE is base of OUTER_TYPE.  */
  else if (contains_type_p (outer_type,
			    offset - ctx.offset, ctx.outer_type, false, true))
    {
      if (dump_file && (dump_flags & TDF_DETAILS))
	fprintf (dump_file, "Second type is base of first\n");
      if (!ctx.maybe_derived_type)
	{
	  if (!maybe_in_construction
	      && types_odr_comparable (outer_type, ctx.outer_type))
	    {
	      if (dump_file && (dump_flags & TDF_DETAILS))
		fprintf (dump_file, "First context does not permit base -> invalid\n");
	      goto invalidate;
	    }
	  /* Pick the base type.  */
	  else if (maybe_in_construction)
	    {
	      outer_type = ctx.outer_type;
	      maybe_in_construction = ctx.maybe_in_construction;
	      maybe_derived_type = ctx.maybe_derived_type;
	      offset = ctx.offset;
	      dynamic = ctx.dynamic;
	      updated = true;
	    }
	}
    }
  /* TODO handle merging using hiearchy. */
  else if (dump_file && (dump_flags & TDF_DETAILS))
    fprintf (dump_file, "Giving up on merge\n");

  updated |= combine_speculation_with (ctx.speculative_outer_type,
				       ctx.speculative_offset,
				       ctx.speculative_maybe_derived_type,
				       otr_type);

  if (updated && dump_file && (dump_flags & TDF_DETAILS))
    {
      fprintf (dump_file, "Updated as:                      ");
      dump (dump_file);
      fprintf (dump_file, "\n");
    }
  return updated;

invalidate:
  invalid = true;
  clear_speculation ();
  clear_outer_type ();
  return true;
}

/* Take non-speculative info, merge it with speculative and clear speculation.
   Used when we no longer manage to keep track of actual outer type, but we
   think it is still there.

   If OTR_TYPE is set, the transformation can be done more effectively assuming
   that context is going to be used only that way.  */

void
ipa_polymorphic_call_context::make_speculative (tree otr_type)
{
  tree spec_outer_type = outer_type;
  HOST_WIDE_INT spec_offset = offset;
  bool spec_maybe_derived_type = maybe_derived_type;

  if (invalid)
    {
      invalid = false;
      clear_outer_type ();
      clear_speculation ();
      return;
    }
  if (!outer_type)
    return;
  clear_outer_type ();
  combine_speculation_with (spec_outer_type, spec_offset,
			    spec_maybe_derived_type,
			    otr_type);
}

/* Use when we can not track dynamic type change.  This speculatively assume
   type change is not happening.  */

void
ipa_polymorphic_call_context::possible_dynamic_type_change (bool in_poly_cdtor,
							    tree otr_type)
{
  if (dynamic)
    make_speculative (otr_type);
  else if (in_poly_cdtor)
    maybe_in_construction = true;
}

/* Return TRUE if this context conveys the same information as OTHER.  */

bool
ipa_polymorphic_call_context::equal_to
    (const ipa_polymorphic_call_context &x) const
{
  if (useless_p ())
    return x.useless_p ();
  if (invalid)
    return x.invalid;
  if (x.useless_p () || x.invalid)
    return false;

  if (outer_type)
    {
      if (!x.outer_type
	  || !types_odr_comparable (outer_type, x.outer_type)
	  || !types_same_for_odr (outer_type, x.outer_type)
	  || offset != x.offset
	  || maybe_in_construction != x.maybe_in_construction
	  || maybe_derived_type != x.maybe_derived_type
	  || dynamic != x.dynamic)
	return false;
    }
  else if (x.outer_type)
    return false;


  if (speculative_outer_type
      && speculation_consistent_p (speculative_outer_type, speculative_offset,
				   speculative_maybe_derived_type, NULL_TREE))
    {
      if (!x.speculative_outer_type)
	return false;

      if (!types_odr_comparable (speculative_outer_type,
				 x.speculative_outer_type)
	  || !types_same_for_odr  (speculative_outer_type,
				   x.speculative_outer_type)
	  || speculative_offset != x.speculative_offset
	  || speculative_maybe_derived_type != x.speculative_maybe_derived_type)
	return false;
    }
  else if (x.speculative_outer_type
	   && x.speculation_consistent_p (x.speculative_outer_type,
					  x.speculative_offset,
				  	  x.speculative_maybe_derived_type,
					  NULL))
    return false;

  return true;
}

/* Modify context to be strictly less restrictive than CTX.  */

bool
ipa_polymorphic_call_context::meet_with (ipa_polymorphic_call_context ctx,
					 tree otr_type)
{
  bool updated = false;

  if (useless_p () || ctx.invalid)
    return false;

  /* Restricting context to inner type makes merging easier, however do not
     do that unless we know how the context is used (OTR_TYPE is non-NULL)  */
  if (otr_type && !useless_p () && !ctx.useless_p ())
    {
      restrict_to_inner_class (otr_type);
      ctx.restrict_to_inner_class (otr_type);
      if(invalid)
        return false;
    }

  if (equal_to (ctx))
    return false;

  if (ctx.useless_p () || invalid)
    {
      *this = ctx;
      return true;
    }

  if (dump_file && (dump_flags & TDF_DETAILS))
    {
      fprintf (dump_file, "Polymorphic call context meet:");
      dump (dump_file);
      fprintf (dump_file, "With context:                    ");
      ctx.dump (dump_file);
      if (otr_type)
	{
          fprintf (dump_file, "To be used with type:            ");
	  print_generic_expr (dump_file, otr_type, TDF_SLIM);
          fprintf (dump_file, "\n");
	}
    }

  if (!dynamic && ctx.dynamic)
    {
      dynamic = true;
      updated = true;
    }

  /* If call is known to be invalid, we are done.  */
  if (!outer_type)
    ;
  else if (!ctx.outer_type)
    {
      clear_outer_type ();
      updated = true;
    }
  /* If types are known to be same, merging is quite easy.  */
  else if (types_must_be_same_for_odr (outer_type, ctx.outer_type))
    {
      if (offset != ctx.offset
	  && TYPE_SIZE (outer_type)
	  && TREE_CODE (TYPE_SIZE (outer_type)) == INTEGER_CST)
	{
	  if (dump_file && (dump_flags & TDF_DETAILS))
	    fprintf (dump_file, "Outer types match, offset mismatch -> clearing\n");
	  clear_outer_type ();
	  return true;
	}
      if (dump_file && (dump_flags & TDF_DETAILS))
        fprintf (dump_file, "Outer types match, merging flags\n");
      if (!maybe_in_construction && ctx.maybe_in_construction)
	{
	  updated = true;
	  maybe_in_construction = true;
	}
      if (!maybe_derived_type && ctx.maybe_derived_type)
	{
	  updated = true;
	  maybe_derived_type = true;
	}
      if (!dynamic && ctx.dynamic)
	{
	  updated = true;
	  dynamic = true;
	}
    }
  /* See if one type contains the other as a field (not base).  */
  else if (contains_type_p (ctx.outer_type, ctx.offset - offset,
			    outer_type, false, false))
    {
      if (dump_file && (dump_flags & TDF_DETAILS))
	fprintf (dump_file, "Second type contain the first as a field\n");

      /* The second type is more specified, so we keep the first.
         We need to set DYNAMIC flag to avoid declaring context INVALID
	 of OFFSET ends up being out of range.  */
      if (!dynamic
	  && (ctx.dynamic
	      || (!otr_type
		  && (!TYPE_SIZE (ctx.outer_type)
		      || !TYPE_SIZE (outer_type)
		      || !operand_equal_p (TYPE_SIZE (ctx.outer_type),
					   TYPE_SIZE (outer_type), 0)))))
	{
	  dynamic = true;
	  updated = true;
	}
    }
  else if (contains_type_p (outer_type, offset - ctx.offset,
			    ctx.outer_type, false, false))
    {
      if (dump_file && (dump_flags & TDF_DETAILS))
	fprintf (dump_file, "First type contain the second as a field\n");

      if (!dynamic
	  && (ctx.dynamic
	      || (!otr_type
		  && (!TYPE_SIZE (ctx.outer_type)
		      || !TYPE_SIZE (outer_type)
		      || !operand_equal_p (TYPE_SIZE (ctx.outer_type),
					   TYPE_SIZE (outer_type), 0)))))
	dynamic = true;
      outer_type = ctx.outer_type;
      offset = ctx.offset;
      dynamic = ctx.dynamic;
      maybe_in_construction = ctx.maybe_in_construction;
      maybe_derived_type = ctx.maybe_derived_type;
      updated = true;
    }
  /* See if OUTER_TYPE is base of CTX.OUTER_TYPE.  */
  else if (contains_type_p (ctx.outer_type,
			    ctx.offset - offset, outer_type, false, true))
    {
      if (dump_file && (dump_flags & TDF_DETAILS))
	fprintf (dump_file, "First type is base of second\n");
      if (!maybe_derived_type)
	{
	  maybe_derived_type = true;
	  updated = true;
	}
      if (!maybe_in_construction && ctx.maybe_in_construction)
	{
	  maybe_in_construction = true;
	  updated = true;
	}
      if (!dynamic && ctx.dynamic)
	{
	  dynamic = true;
	  updated = true;
	}
    }
  /* See if CTX.OUTER_TYPE is base of OUTER_TYPE.  */
  else if (contains_type_p (outer_type,
			    offset - ctx.offset, ctx.outer_type, false, true))
    {
      if (dump_file && (dump_flags & TDF_DETAILS))
	fprintf (dump_file, "Second type is base of first\n");
      outer_type = ctx.outer_type;
      offset = ctx.offset;
      updated = true;
      if (!maybe_derived_type)
	maybe_derived_type = true;
      if (!maybe_in_construction && ctx.maybe_in_construction)
	maybe_in_construction = true;
      if (!dynamic && ctx.dynamic)
	dynamic = true;
    }
  /* TODO handle merging using hiearchy. */
  else
    {
      if (dump_file && (dump_flags & TDF_DETAILS))
        fprintf (dump_file, "Giving up on meet\n");
      clear_outer_type ();
      updated = true;
    }

  updated |= meet_speculation_with (ctx.speculative_outer_type,
				    ctx.speculative_offset,
				    ctx.speculative_maybe_derived_type,
				    otr_type);

  if (updated && dump_file && (dump_flags & TDF_DETAILS))
    {
      fprintf (dump_file, "Updated as:                      ");
      dump (dump_file);
      fprintf (dump_file, "\n");
    }
  return updated;
}