summaryrefslogtreecommitdiff
path: root/gcc/tree-ssa-loop-im.c
blob: 85d811868b758480eb75908a2d9fd6ae0735ec93 (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
2519
2520
2521
2522
2523
2524
2525
2526
2527
2528
2529
2530
2531
2532
2533
2534
2535
2536
2537
2538
2539
2540
2541
2542
2543
2544
2545
2546
2547
2548
2549
2550
2551
2552
2553
2554
2555
2556
2557
2558
2559
2560
2561
2562
2563
2564
2565
2566
2567
2568
2569
2570
2571
2572
2573
2574
2575
2576
2577
2578
2579
2580
2581
2582
2583
2584
2585
2586
2587
2588
2589
2590
2591
2592
2593
2594
2595
2596
2597
2598
2599
/* Loop invariant motion.
   Copyright (C) 2003-2014 Free Software Foundation, Inc.

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation; either version 3, or (at your option) any
later version.

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

You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING3.  If not see
<http://www.gnu.org/licenses/>.  */

#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"
#include "tree.h"
#include "tm_p.h"
#include "predict.h"
#include "vec.h"
#include "hashtab.h"
#include "hash-set.h"
#include "machmode.h"
#include "hard-reg-set.h"
#include "input.h"
#include "function.h"
#include "dominance.h"
#include "cfg.h"
#include "cfganal.h"
#include "basic-block.h"
#include "gimple-pretty-print.h"
#include "hash-map.h"
#include "hash-table.h"
#include "tree-ssa-alias.h"
#include "internal-fn.h"
#include "tree-eh.h"
#include "gimple-expr.h"
#include "is-a.h"
#include "gimple.h"
#include "gimplify.h"
#include "gimple-iterator.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 "tree-ssa-loop-manip.h"
#include "tree-ssa-loop.h"
#include "tree-into-ssa.h"
#include "cfgloop.h"
#include "domwalk.h"
#include "params.h"
#include "tree-pass.h"
#include "flags.h"
#include "tree-affine.h"
#include "tree-ssa-propagate.h"
#include "trans-mem.h"
#include "gimple-fold.h"

/* TODO:  Support for predicated code motion.  I.e.

   while (1)
     {
       if (cond)
	 {
	   a = inv;
	   something;
	 }
     }

   Where COND and INV are invariants, but evaluating INV may trap or be
   invalid from some other reason if !COND.  This may be transformed to

   if (cond)
     a = inv;
   while (1)
     {
       if (cond)
	 something;
     }  */

/* The auxiliary data kept for each statement.  */

struct lim_aux_data
{
  struct loop *max_loop;	/* The outermost loop in that the statement
				   is invariant.  */

  struct loop *tgt_loop;	/* The loop out of that we want to move the
				   invariant.  */

  struct loop *always_executed_in;
				/* The outermost loop for that we are sure
				   the statement is executed if the loop
				   is entered.  */

  unsigned cost;		/* Cost of the computation performed by the
				   statement.  */

  vec<gimple> depends;		/* Vector of statements that must be also
				   hoisted out of the loop when this statement
				   is hoisted; i.e. those that define the
				   operands of the statement and are inside of
				   the MAX_LOOP loop.  */
};

/* Maps statements to their lim_aux_data.  */

static hash_map<gimple, lim_aux_data *> *lim_aux_data_map;

/* Description of a memory reference location.  */

typedef struct mem_ref_loc
{
  tree *ref;			/* The reference itself.  */
  gimple stmt;			/* The statement in that it occurs.  */
} *mem_ref_loc_p;


/* Description of a memory reference.  */

typedef struct im_mem_ref
{
  unsigned id;			/* ID assigned to the memory reference
				   (its index in memory_accesses.refs_list)  */
  hashval_t hash;		/* Its hash value.  */

  /* The memory access itself and associated caching of alias-oracle
     query meta-data.  */
  ao_ref mem;

  bitmap stored;		/* The set of loops in that this memory location
				   is stored to.  */
  vec<mem_ref_loc>		accesses_in_loop;
				/* The locations of the accesses.  Vector
				   indexed by the loop number.  */

  /* The following sets are computed on demand.  We keep both set and
     its complement, so that we know whether the information was
     already computed or not.  */
  bitmap_head indep_loop;	/* The set of loops in that the memory
				   reference is independent, meaning:
				   If it is stored in the loop, this store
				     is independent on all other loads and
				     stores.
				   If it is only loaded, then it is independent
				     on all stores in the loop.  */
  bitmap_head dep_loop;		/* The complement of INDEP_LOOP.  */
} *mem_ref_p;

/* We use two bits per loop in the ref->{in,}dep_loop bitmaps, the first
   to record (in)dependence against stores in the loop and its subloops, the
   second to record (in)dependence against all references in the loop
   and its subloops.  */
#define LOOP_DEP_BIT(loopnum, storedp) (2 * (loopnum) + (storedp ? 1 : 0))

/* Mem_ref hashtable helpers.  */

struct mem_ref_hasher : typed_noop_remove <im_mem_ref>
{
  typedef im_mem_ref value_type;
  typedef tree_node compare_type;
  static inline hashval_t hash (const value_type *);
  static inline bool equal (const value_type *, const compare_type *);
};

/* A hash function for struct im_mem_ref object OBJ.  */

inline hashval_t
mem_ref_hasher::hash (const value_type *mem)
{
  return mem->hash;
}

/* An equality function for struct im_mem_ref object MEM1 with
   memory reference OBJ2.  */

inline bool
mem_ref_hasher::equal (const value_type *mem1, const compare_type *obj2)
{
  return operand_equal_p (mem1->mem.ref, (const_tree) obj2, 0);
}


/* Description of memory accesses in loops.  */

static struct
{
  /* The hash table of memory references accessed in loops.  */
  hash_table<mem_ref_hasher> *refs;

  /* The list of memory references.  */
  vec<mem_ref_p> refs_list;

  /* The set of memory references accessed in each loop.  */
  vec<bitmap_head> refs_in_loop;

  /* The set of memory references stored in each loop.  */
  vec<bitmap_head> refs_stored_in_loop;

  /* The set of memory references stored in each loop, including subloops .  */
  vec<bitmap_head> all_refs_stored_in_loop;

  /* Cache for expanding memory addresses.  */
  hash_map<tree, name_expansion *> *ttae_cache;
} memory_accesses;

/* Obstack for the bitmaps in the above data structures.  */
static bitmap_obstack lim_bitmap_obstack;
static obstack mem_ref_obstack;

static bool ref_indep_loop_p (struct loop *, mem_ref_p);

/* Minimum cost of an expensive expression.  */
#define LIM_EXPENSIVE ((unsigned) PARAM_VALUE (PARAM_LIM_EXPENSIVE))

/* The outermost loop for which execution of the header guarantees that the
   block will be executed.  */
#define ALWAYS_EXECUTED_IN(BB) ((struct loop *) (BB)->aux)
#define SET_ALWAYS_EXECUTED_IN(BB, VAL) ((BB)->aux = (void *) (VAL))

/* ID of the shared unanalyzable mem.  */
#define UNANALYZABLE_MEM_ID 0

/* Whether the reference was analyzable.  */
#define MEM_ANALYZABLE(REF) ((REF)->id != UNANALYZABLE_MEM_ID)

static struct lim_aux_data *
init_lim_data (gimple stmt)
{
  lim_aux_data *p = XCNEW (struct lim_aux_data);
  lim_aux_data_map->put (stmt, p);

  return p;
}

static struct lim_aux_data *
get_lim_data (gimple stmt)
{
  lim_aux_data **p = lim_aux_data_map->get (stmt);
  if (!p)
    return NULL;

  return *p;
}

/* Releases the memory occupied by DATA.  */

static void
free_lim_aux_data (struct lim_aux_data *data)
{
  data->depends.release ();
  free (data);
}

static void
clear_lim_data (gimple stmt)
{
  lim_aux_data **p = lim_aux_data_map->get (stmt);
  if (!p)
    return;

  free_lim_aux_data (*p);
  *p = NULL;
}


/* The possibilities of statement movement.  */
enum move_pos
  {
    MOVE_IMPOSSIBLE,		/* No movement -- side effect expression.  */
    MOVE_PRESERVE_EXECUTION,	/* Must not cause the non-executed statement
				   become executed -- memory accesses, ... */
    MOVE_POSSIBLE		/* Unlimited movement.  */
  };


/* If it is possible to hoist the statement STMT unconditionally,
   returns MOVE_POSSIBLE.
   If it is possible to hoist the statement STMT, but we must avoid making
   it executed if it would not be executed in the original program (e.g.
   because it may trap), return MOVE_PRESERVE_EXECUTION.
   Otherwise return MOVE_IMPOSSIBLE.  */

enum move_pos
movement_possibility (gimple stmt)
{
  tree lhs;
  enum move_pos ret = MOVE_POSSIBLE;

  if (flag_unswitch_loops
      && gimple_code (stmt) == GIMPLE_COND)
    {
      /* If we perform unswitching, force the operands of the invariant
	 condition to be moved out of the loop.  */
      return MOVE_POSSIBLE;
    }

  if (gimple_code (stmt) == GIMPLE_PHI
      && gimple_phi_num_args (stmt) <= 2
      && !virtual_operand_p (gimple_phi_result (stmt))
      && !SSA_NAME_OCCURS_IN_ABNORMAL_PHI (gimple_phi_result (stmt)))
    return MOVE_POSSIBLE;

  if (gimple_get_lhs (stmt) == NULL_TREE)
    return MOVE_IMPOSSIBLE;

  if (gimple_vdef (stmt))
    return MOVE_IMPOSSIBLE;

  if (stmt_ends_bb_p (stmt)
      || gimple_has_volatile_ops (stmt)
      || gimple_has_side_effects (stmt)
      || stmt_could_throw_p (stmt))
    return MOVE_IMPOSSIBLE;

  if (is_gimple_call (stmt))
    {
      /* While pure or const call is guaranteed to have no side effects, we
	 cannot move it arbitrarily.  Consider code like

	 char *s = something ();

	 while (1)
	   {
	     if (s)
	       t = strlen (s);
	     else
	       t = 0;
	   }

	 Here the strlen call cannot be moved out of the loop, even though
	 s is invariant.  In addition to possibly creating a call with
	 invalid arguments, moving out a function call that is not executed
	 may cause performance regressions in case the call is costly and
	 not executed at all.  */
      ret = MOVE_PRESERVE_EXECUTION;
      lhs = gimple_call_lhs (stmt);
    }
  else if (is_gimple_assign (stmt))
    lhs = gimple_assign_lhs (stmt);
  else
    return MOVE_IMPOSSIBLE;

  if (TREE_CODE (lhs) == SSA_NAME
      && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (lhs))
    return MOVE_IMPOSSIBLE;

  if (TREE_CODE (lhs) != SSA_NAME
      || gimple_could_trap_p (stmt))
    return MOVE_PRESERVE_EXECUTION;

  /* Non local loads in a transaction cannot be hoisted out.  Well,
     unless the load happens on every path out of the loop, but we
     don't take this into account yet.  */
  if (flag_tm
      && gimple_in_transaction (stmt)
      && gimple_assign_single_p (stmt))
    {
      tree rhs = gimple_assign_rhs1 (stmt);
      if (DECL_P (rhs) && is_global_var (rhs))
	{
	  if (dump_file)
	    {
	      fprintf (dump_file, "Cannot hoist conditional load of ");
	      print_generic_expr (dump_file, rhs, TDF_SLIM);
	      fprintf (dump_file, " because it is in a transaction.\n");
	    }
	  return MOVE_IMPOSSIBLE;
	}
    }

  return ret;
}

/* Suppose that operand DEF is used inside the LOOP.  Returns the outermost
   loop to that we could move the expression using DEF if it did not have
   other operands, i.e. the outermost loop enclosing LOOP in that the value
   of DEF is invariant.  */

static struct loop *
outermost_invariant_loop (tree def, struct loop *loop)
{
  gimple def_stmt;
  basic_block def_bb;
  struct loop *max_loop;
  struct lim_aux_data *lim_data;

  if (!def)
    return superloop_at_depth (loop, 1);

  if (TREE_CODE (def) != SSA_NAME)
    {
      gcc_assert (is_gimple_min_invariant (def));
      return superloop_at_depth (loop, 1);
    }

  def_stmt = SSA_NAME_DEF_STMT (def);
  def_bb = gimple_bb (def_stmt);
  if (!def_bb)
    return superloop_at_depth (loop, 1);

  max_loop = find_common_loop (loop, def_bb->loop_father);

  lim_data = get_lim_data (def_stmt);
  if (lim_data != NULL && lim_data->max_loop != NULL)
    max_loop = find_common_loop (max_loop,
				 loop_outer (lim_data->max_loop));
  if (max_loop == loop)
    return NULL;
  max_loop = superloop_at_depth (loop, loop_depth (max_loop) + 1);

  return max_loop;
}

/* DATA is a structure containing information associated with a statement
   inside LOOP.  DEF is one of the operands of this statement.

   Find the outermost loop enclosing LOOP in that value of DEF is invariant
   and record this in DATA->max_loop field.  If DEF itself is defined inside
   this loop as well (i.e. we need to hoist it out of the loop if we want
   to hoist the statement represented by DATA), record the statement in that
   DEF is defined to the DATA->depends list.  Additionally if ADD_COST is true,
   add the cost of the computation of DEF to the DATA->cost.

   If DEF is not invariant in LOOP, return false.  Otherwise return TRUE.  */

static bool
add_dependency (tree def, struct lim_aux_data *data, struct loop *loop,
		bool add_cost)
{
  gimple def_stmt = SSA_NAME_DEF_STMT (def);
  basic_block def_bb = gimple_bb (def_stmt);
  struct loop *max_loop;
  struct lim_aux_data *def_data;

  if (!def_bb)
    return true;

  max_loop = outermost_invariant_loop (def, loop);
  if (!max_loop)
    return false;

  if (flow_loop_nested_p (data->max_loop, max_loop))
    data->max_loop = max_loop;

  def_data = get_lim_data (def_stmt);
  if (!def_data)
    return true;

  if (add_cost
      /* Only add the cost if the statement defining DEF is inside LOOP,
	 i.e. if it is likely that by moving the invariants dependent
	 on it, we will be able to avoid creating a new register for
	 it (since it will be only used in these dependent invariants).  */
      && def_bb->loop_father == loop)
    data->cost += def_data->cost;

  data->depends.safe_push (def_stmt);

  return true;
}

/* Returns an estimate for a cost of statement STMT.  The values here
   are just ad-hoc constants, similar to costs for inlining.  */

static unsigned
stmt_cost (gimple stmt)
{
  /* Always try to create possibilities for unswitching.  */
  if (gimple_code (stmt) == GIMPLE_COND
      || gimple_code (stmt) == GIMPLE_PHI)
    return LIM_EXPENSIVE;

  /* We should be hoisting calls if possible.  */
  if (is_gimple_call (stmt))
    {
      tree fndecl;

      /* Unless the call is a builtin_constant_p; this always folds to a
	 constant, so moving it is useless.  */
      fndecl = gimple_call_fndecl (stmt);
      if (fndecl
	  && DECL_BUILT_IN_CLASS (fndecl) == BUILT_IN_NORMAL
	  && DECL_FUNCTION_CODE (fndecl) == BUILT_IN_CONSTANT_P)
	return 0;

      return LIM_EXPENSIVE;
    }

  /* Hoisting memory references out should almost surely be a win.  */
  if (gimple_references_memory_p (stmt))
    return LIM_EXPENSIVE;

  if (gimple_code (stmt) != GIMPLE_ASSIGN)
    return 1;

  switch (gimple_assign_rhs_code (stmt))
    {
    case MULT_EXPR:
    case WIDEN_MULT_EXPR:
    case WIDEN_MULT_PLUS_EXPR:
    case WIDEN_MULT_MINUS_EXPR:
    case DOT_PROD_EXPR:
    case FMA_EXPR:
    case TRUNC_DIV_EXPR:
    case CEIL_DIV_EXPR:
    case FLOOR_DIV_EXPR:
    case ROUND_DIV_EXPR:
    case EXACT_DIV_EXPR:
    case CEIL_MOD_EXPR:
    case FLOOR_MOD_EXPR:
    case ROUND_MOD_EXPR:
    case TRUNC_MOD_EXPR:
    case RDIV_EXPR:
      /* Division and multiplication are usually expensive.  */
      return LIM_EXPENSIVE;

    case LSHIFT_EXPR:
    case RSHIFT_EXPR:
    case WIDEN_LSHIFT_EXPR:
    case LROTATE_EXPR:
    case RROTATE_EXPR:
      /* Shifts and rotates are usually expensive.  */
      return LIM_EXPENSIVE;

    case CONSTRUCTOR:
      /* Make vector construction cost proportional to the number
         of elements.  */
      return CONSTRUCTOR_NELTS (gimple_assign_rhs1 (stmt));

    case SSA_NAME:
    case PAREN_EXPR:
      /* Whether or not something is wrapped inside a PAREN_EXPR
         should not change move cost.  Nor should an intermediate
	 unpropagated SSA name copy.  */
      return 0;

    default:
      return 1;
    }
}

/* Finds the outermost loop between OUTER and LOOP in that the memory reference
   REF is independent.  If REF is not independent in LOOP, NULL is returned
   instead.  */

static struct loop *
outermost_indep_loop (struct loop *outer, struct loop *loop, mem_ref_p ref)
{
  struct loop *aloop;

  if (ref->stored && bitmap_bit_p (ref->stored, loop->num))
    return NULL;

  for (aloop = outer;
       aloop != loop;
       aloop = superloop_at_depth (loop, loop_depth (aloop) + 1))
    if ((!ref->stored || !bitmap_bit_p (ref->stored, aloop->num))
	&& ref_indep_loop_p (aloop, ref))
      return aloop;

  if (ref_indep_loop_p (loop, ref))
    return loop;
  else
    return NULL;
}

/* If there is a simple load or store to a memory reference in STMT, returns
   the location of the memory reference, and sets IS_STORE according to whether
   it is a store or load.  Otherwise, returns NULL.  */

static tree *
simple_mem_ref_in_stmt (gimple stmt, bool *is_store)
{
  tree *lhs, *rhs;

  /* Recognize SSA_NAME = MEM and MEM = (SSA_NAME | invariant) patterns.  */
  if (!gimple_assign_single_p (stmt))
    return NULL;

  lhs = gimple_assign_lhs_ptr (stmt);
  rhs = gimple_assign_rhs1_ptr (stmt);

  if (TREE_CODE (*lhs) == SSA_NAME && gimple_vuse (stmt))
    {
      *is_store = false;
      return rhs;
    }
  else if (gimple_vdef (stmt)
	   && (TREE_CODE (*rhs) == SSA_NAME || is_gimple_min_invariant (*rhs)))
    {
      *is_store = true;
      return lhs;
    }
  else
    return NULL;
}

/* Returns the memory reference contained in STMT.  */

static mem_ref_p
mem_ref_in_stmt (gimple stmt)
{
  bool store;
  tree *mem = simple_mem_ref_in_stmt (stmt, &store);
  hashval_t hash;
  mem_ref_p ref;

  if (!mem)
    return NULL;
  gcc_assert (!store);

  hash = iterative_hash_expr (*mem, 0);
  ref = memory_accesses.refs->find_with_hash (*mem, hash);

  gcc_assert (ref != NULL);
  return ref;
}

/* From a controlling predicate in DOM determine the arguments from
   the PHI node PHI that are chosen if the predicate evaluates to
   true and false and store them to *TRUE_ARG_P and *FALSE_ARG_P if
   they are non-NULL.  Returns true if the arguments can be determined,
   else return false.  */

static bool
extract_true_false_args_from_phi (basic_block dom, gimple phi,
				  tree *true_arg_p, tree *false_arg_p)
{
  basic_block bb = gimple_bb (phi);
  edge true_edge, false_edge, tem;
  tree arg0 = NULL_TREE, arg1 = NULL_TREE;

  /* We have to verify that one edge into the PHI node is dominated
     by the true edge of the predicate block and the other edge
     dominated by the false edge.  This ensures that the PHI argument
     we are going to take is completely determined by the path we
     take from the predicate block.
     We can only use BB dominance checks below if the destination of
     the true/false edges are dominated by their edge, thus only
     have a single predecessor.  */
  extract_true_false_edges_from_block (dom, &true_edge, &false_edge);
  tem = EDGE_PRED (bb, 0);
  if (tem == true_edge
      || (single_pred_p (true_edge->dest)
	  && (tem->src == true_edge->dest
	      || dominated_by_p (CDI_DOMINATORS,
				 tem->src, true_edge->dest))))
    arg0 = PHI_ARG_DEF (phi, tem->dest_idx);
  else if (tem == false_edge
	   || (single_pred_p (false_edge->dest)
	       && (tem->src == false_edge->dest
		   || dominated_by_p (CDI_DOMINATORS,
				      tem->src, false_edge->dest))))
    arg1 = PHI_ARG_DEF (phi, tem->dest_idx);
  else
    return false;
  tem = EDGE_PRED (bb, 1);
  if (tem == true_edge
      || (single_pred_p (true_edge->dest)
	  && (tem->src == true_edge->dest
	      || dominated_by_p (CDI_DOMINATORS,
				 tem->src, true_edge->dest))))
    arg0 = PHI_ARG_DEF (phi, tem->dest_idx);
  else if (tem == false_edge
	   || (single_pred_p (false_edge->dest)
	       && (tem->src == false_edge->dest
		   || dominated_by_p (CDI_DOMINATORS,
				      tem->src, false_edge->dest))))
    arg1 = PHI_ARG_DEF (phi, tem->dest_idx);
  else
    return false;
  if (!arg0 || !arg1)
    return false;

  if (true_arg_p)
    *true_arg_p = arg0;
  if (false_arg_p)
    *false_arg_p = arg1;

  return true;
}

/* Determine the outermost loop to that it is possible to hoist a statement
   STMT and store it to LIM_DATA (STMT)->max_loop.  To do this we determine
   the outermost loop in that the value computed by STMT is invariant.
   If MUST_PRESERVE_EXEC is true, additionally choose such a loop that
   we preserve the fact whether STMT is executed.  It also fills other related
   information to LIM_DATA (STMT).

   The function returns false if STMT cannot be hoisted outside of the loop it
   is defined in, and true otherwise.  */

static bool
determine_max_movement (gimple stmt, bool must_preserve_exec)
{
  basic_block bb = gimple_bb (stmt);
  struct loop *loop = bb->loop_father;
  struct loop *level;
  struct lim_aux_data *lim_data = get_lim_data (stmt);
  tree val;
  ssa_op_iter iter;

  if (must_preserve_exec)
    level = ALWAYS_EXECUTED_IN (bb);
  else
    level = superloop_at_depth (loop, 1);
  lim_data->max_loop = level;

  if (gimple_code (stmt) == GIMPLE_PHI)
    {
      use_operand_p use_p;
      unsigned min_cost = UINT_MAX;
      unsigned total_cost = 0;
      struct lim_aux_data *def_data;

      /* We will end up promoting dependencies to be unconditionally
	 evaluated.  For this reason the PHI cost (and thus the
	 cost we remove from the loop by doing the invariant motion)
	 is that of the cheapest PHI argument dependency chain.  */
      FOR_EACH_PHI_ARG (use_p, stmt, iter, SSA_OP_USE)
	{
	  val = USE_FROM_PTR (use_p);

	  if (TREE_CODE (val) != SSA_NAME)
	    {
	      /* Assign const 1 to constants.  */
	      min_cost = MIN (min_cost, 1);
	      total_cost += 1;
	      continue;
	    }
	  if (!add_dependency (val, lim_data, loop, false))
	    return false;

	  gimple def_stmt = SSA_NAME_DEF_STMT (val);
	  if (gimple_bb (def_stmt)
	      && gimple_bb (def_stmt)->loop_father == loop)
	    {
	      def_data = get_lim_data (def_stmt);
	      if (def_data)
		{
		  min_cost = MIN (min_cost, def_data->cost);
		  total_cost += def_data->cost;
		}
	    }
	}

      min_cost = MIN (min_cost, total_cost);
      lim_data->cost += min_cost;

      if (gimple_phi_num_args (stmt) > 1)
	{
	  basic_block dom = get_immediate_dominator (CDI_DOMINATORS, bb);
	  gimple cond;
	  if (gsi_end_p (gsi_last_bb (dom)))
	    return false;
	  cond = gsi_stmt (gsi_last_bb (dom));
	  if (gimple_code (cond) != GIMPLE_COND)
	    return false;
	  /* Verify that this is an extended form of a diamond and
	     the PHI arguments are completely controlled by the
	     predicate in DOM.  */
	  if (!extract_true_false_args_from_phi (dom, stmt, NULL, NULL))
	    return false;

	  /* Fold in dependencies and cost of the condition.  */
	  FOR_EACH_SSA_TREE_OPERAND (val, cond, iter, SSA_OP_USE)
	    {
	      if (!add_dependency (val, lim_data, loop, false))
		return false;
	      def_data = get_lim_data (SSA_NAME_DEF_STMT (val));
	      if (def_data)
		total_cost += def_data->cost;
	    }

	  /* We want to avoid unconditionally executing very expensive
	     operations.  As costs for our dependencies cannot be
	     negative just claim we are not invariand for this case.
	     We also are not sure whether the control-flow inside the
	     loop will vanish.  */
	  if (total_cost - min_cost >= 2 * LIM_EXPENSIVE
	      && !(min_cost != 0
		   && total_cost / min_cost <= 2))
	    return false;

	  /* Assume that the control-flow in the loop will vanish.
	     ???  We should verify this and not artificially increase
	     the cost if that is not the case.  */
	  lim_data->cost += stmt_cost (stmt);
	}

      return true;
    }
  else
    FOR_EACH_SSA_TREE_OPERAND (val, stmt, iter, SSA_OP_USE)
      if (!add_dependency (val, lim_data, loop, true))
	return false;

  if (gimple_vuse (stmt))
    {
      mem_ref_p ref = mem_ref_in_stmt (stmt);

      if (ref)
	{
	  lim_data->max_loop
		  = outermost_indep_loop (lim_data->max_loop, loop, ref);
	  if (!lim_data->max_loop)
	    return false;
	}
      else
	{
	  if ((val = gimple_vuse (stmt)) != NULL_TREE)
	    {
	      if (!add_dependency (val, lim_data, loop, false))
		return false;
	    }
	}
    }

  lim_data->cost += stmt_cost (stmt);

  return true;
}

/* Suppose that some statement in ORIG_LOOP is hoisted to the loop LEVEL,
   and that one of the operands of this statement is computed by STMT.
   Ensure that STMT (together with all the statements that define its
   operands) is hoisted at least out of the loop LEVEL.  */

static void
set_level (gimple stmt, struct loop *orig_loop, struct loop *level)
{
  struct loop *stmt_loop = gimple_bb (stmt)->loop_father;
  struct lim_aux_data *lim_data;
  gimple dep_stmt;
  unsigned i;

  stmt_loop = find_common_loop (orig_loop, stmt_loop);
  lim_data = get_lim_data (stmt);
  if (lim_data != NULL && lim_data->tgt_loop != NULL)
    stmt_loop = find_common_loop (stmt_loop,
				  loop_outer (lim_data->tgt_loop));
  if (flow_loop_nested_p (stmt_loop, level))
    return;

  gcc_assert (level == lim_data->max_loop
	      || flow_loop_nested_p (lim_data->max_loop, level));

  lim_data->tgt_loop = level;
  FOR_EACH_VEC_ELT (lim_data->depends, i, dep_stmt)
    set_level (dep_stmt, orig_loop, level);
}

/* Determines an outermost loop from that we want to hoist the statement STMT.
   For now we chose the outermost possible loop.  TODO -- use profiling
   information to set it more sanely.  */

static void
set_profitable_level (gimple stmt)
{
  set_level (stmt, gimple_bb (stmt)->loop_father, get_lim_data (stmt)->max_loop);
}

/* Returns true if STMT is a call that has side effects.  */

static bool
nonpure_call_p (gimple stmt)
{
  if (gimple_code (stmt) != GIMPLE_CALL)
    return false;

  return gimple_has_side_effects (stmt);
}

/* Rewrite a/b to a*(1/b).  Return the invariant stmt to process.  */

static gimple
rewrite_reciprocal (gimple_stmt_iterator *bsi)
{
  gimple stmt, stmt1, stmt2;
  tree name, lhs, type;
  tree real_one;
  gimple_stmt_iterator gsi;

  stmt = gsi_stmt (*bsi);
  lhs = gimple_assign_lhs (stmt);
  type = TREE_TYPE (lhs);

  real_one = build_one_cst (type);

  name = make_temp_ssa_name (type, NULL, "reciptmp");
  stmt1 = gimple_build_assign_with_ops (RDIV_EXPR, name, real_one,
					gimple_assign_rhs2 (stmt));

  stmt2 = gimple_build_assign_with_ops (MULT_EXPR, lhs, name,
					gimple_assign_rhs1 (stmt));

  /* Replace division stmt with reciprocal and multiply stmts.
     The multiply stmt is not invariant, so update iterator
     and avoid rescanning.  */
  gsi = *bsi;
  gsi_insert_before (bsi, stmt1, GSI_NEW_STMT);
  gsi_replace (&gsi, stmt2, true);

  /* Continue processing with invariant reciprocal statement.  */
  return stmt1;
}

/* Check if the pattern at *BSI is a bittest of the form
   (A >> B) & 1 != 0 and in this case rewrite it to A & (1 << B) != 0.  */

static gimple
rewrite_bittest (gimple_stmt_iterator *bsi)
{
  gimple stmt, use_stmt, stmt1, stmt2;
  tree lhs, name, t, a, b;
  use_operand_p use;

  stmt = gsi_stmt (*bsi);
  lhs = gimple_assign_lhs (stmt);

  /* Verify that the single use of lhs is a comparison against zero.  */
  if (TREE_CODE (lhs) != SSA_NAME
      || !single_imm_use (lhs, &use, &use_stmt)
      || gimple_code (use_stmt) != GIMPLE_COND)
    return stmt;
  if (gimple_cond_lhs (use_stmt) != lhs
      || (gimple_cond_code (use_stmt) != NE_EXPR
	  && gimple_cond_code (use_stmt) != EQ_EXPR)
      || !integer_zerop (gimple_cond_rhs (use_stmt)))
    return stmt;

  /* Get at the operands of the shift.  The rhs is TMP1 & 1.  */
  stmt1 = SSA_NAME_DEF_STMT (gimple_assign_rhs1 (stmt));
  if (gimple_code (stmt1) != GIMPLE_ASSIGN)
    return stmt;

  /* There is a conversion in between possibly inserted by fold.  */
  if (CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (stmt1)))
    {
      t = gimple_assign_rhs1 (stmt1);
      if (TREE_CODE (t) != SSA_NAME
	  || !has_single_use (t))
	return stmt;
      stmt1 = SSA_NAME_DEF_STMT (t);
      if (gimple_code (stmt1) != GIMPLE_ASSIGN)
	return stmt;
    }

  /* Verify that B is loop invariant but A is not.  Verify that with
     all the stmt walking we are still in the same loop.  */
  if (gimple_assign_rhs_code (stmt1) != RSHIFT_EXPR
      || loop_containing_stmt (stmt1) != loop_containing_stmt (stmt))
    return stmt;

  a = gimple_assign_rhs1 (stmt1);
  b = gimple_assign_rhs2 (stmt1);

  if (outermost_invariant_loop (b, loop_containing_stmt (stmt1)) != NULL
      && outermost_invariant_loop (a, loop_containing_stmt (stmt1)) == NULL)
    {
      gimple_stmt_iterator rsi;

      /* 1 << B */
      t = fold_build2 (LSHIFT_EXPR, TREE_TYPE (a),
		       build_int_cst (TREE_TYPE (a), 1), b);
      name = make_temp_ssa_name (TREE_TYPE (a), NULL, "shifttmp");
      stmt1 = gimple_build_assign (name, t);

      /* A & (1 << B) */
      t = fold_build2 (BIT_AND_EXPR, TREE_TYPE (a), a, name);
      name = make_temp_ssa_name (TREE_TYPE (a), NULL, "shifttmp");
      stmt2 = gimple_build_assign (name, t);

      /* Replace the SSA_NAME we compare against zero.  Adjust
	 the type of zero accordingly.  */
      SET_USE (use, name);
      gimple_cond_set_rhs (use_stmt, build_int_cst_type (TREE_TYPE (name), 0));

      /* Don't use gsi_replace here, none of the new assignments sets
	 the variable originally set in stmt.  Move bsi to stmt1, and
	 then remove the original stmt, so that we get a chance to
	 retain debug info for it.  */
      rsi = *bsi;
      gsi_insert_before (bsi, stmt1, GSI_NEW_STMT);
      gsi_insert_before (&rsi, stmt2, GSI_SAME_STMT);
      gsi_remove (&rsi, true);

      return stmt1;
    }

  return stmt;
}

/* For each statement determines the outermost loop in that it is invariant,
   -   statements on whose motion it depends and the cost of the computation.
   -   This information is stored to the LIM_DATA structure associated with
   -   each statement.  */
class invariantness_dom_walker : public dom_walker
{
public:
  invariantness_dom_walker (cdi_direction direction)
    : dom_walker (direction) {}

  virtual void before_dom_children (basic_block);
};

/* Determine the outermost loops in that statements in basic block BB are
   invariant, and record them to the LIM_DATA associated with the statements.
   Callback for dom_walker.  */

void
invariantness_dom_walker::before_dom_children (basic_block bb)
{
  enum move_pos pos;
  gimple_stmt_iterator bsi;
  gimple stmt;
  bool maybe_never = ALWAYS_EXECUTED_IN (bb) == NULL;
  struct loop *outermost = ALWAYS_EXECUTED_IN (bb);
  struct lim_aux_data *lim_data;

  if (!loop_outer (bb->loop_father))
    return;

  if (dump_file && (dump_flags & TDF_DETAILS))
    fprintf (dump_file, "Basic block %d (loop %d -- depth %d):\n\n",
	     bb->index, bb->loop_father->num, loop_depth (bb->loop_father));

  /* Look at PHI nodes, but only if there is at most two.
     ???  We could relax this further by post-processing the inserted
     code and transforming adjacent cond-exprs with the same predicate
     to control flow again.  */
  bsi = gsi_start_phis (bb);
  if (!gsi_end_p (bsi)
      && ((gsi_next (&bsi), gsi_end_p (bsi))
	  || (gsi_next (&bsi), gsi_end_p (bsi))))
    for (bsi = gsi_start_phis (bb); !gsi_end_p (bsi); gsi_next (&bsi))
      {
	stmt = gsi_stmt (bsi);

	pos = movement_possibility (stmt);
	if (pos == MOVE_IMPOSSIBLE)
	  continue;

	lim_data = init_lim_data (stmt);
	lim_data->always_executed_in = outermost;

	if (!determine_max_movement (stmt, false))
	  {
	    lim_data->max_loop = NULL;
	    continue;
	  }

	if (dump_file && (dump_flags & TDF_DETAILS))
	  {
	    print_gimple_stmt (dump_file, stmt, 2, 0);
	    fprintf (dump_file, "  invariant up to level %d, cost %d.\n\n",
		     loop_depth (lim_data->max_loop),
		     lim_data->cost);
	  }

	if (lim_data->cost >= LIM_EXPENSIVE)
	  set_profitable_level (stmt);
      }

  for (bsi = gsi_start_bb (bb); !gsi_end_p (bsi); gsi_next (&bsi))
    {
      stmt = gsi_stmt (bsi);

      pos = movement_possibility (stmt);
      if (pos == MOVE_IMPOSSIBLE)
	{
	  if (nonpure_call_p (stmt))
	    {
	      maybe_never = true;
	      outermost = NULL;
	    }
	  /* Make sure to note always_executed_in for stores to make
	     store-motion work.  */
	  else if (stmt_makes_single_store (stmt))
	    {
	      struct lim_aux_data *lim_data = init_lim_data (stmt);
	      lim_data->always_executed_in = outermost;
	    }
	  continue;
	}

      if (is_gimple_assign (stmt)
	  && (get_gimple_rhs_class (gimple_assign_rhs_code (stmt))
	      == GIMPLE_BINARY_RHS))
	{
	  tree op0 = gimple_assign_rhs1 (stmt);
	  tree op1 = gimple_assign_rhs2 (stmt);
	  struct loop *ol1 = outermost_invariant_loop (op1,
					loop_containing_stmt (stmt));

	  /* If divisor is invariant, convert a/b to a*(1/b), allowing reciprocal
	     to be hoisted out of loop, saving expensive divide.  */
	  if (pos == MOVE_POSSIBLE
	      && gimple_assign_rhs_code (stmt) == RDIV_EXPR
	      && flag_unsafe_math_optimizations
	      && !flag_trapping_math
	      && ol1 != NULL
	      && outermost_invariant_loop (op0, ol1) == NULL)
	    stmt = rewrite_reciprocal (&bsi);

	  /* If the shift count is invariant, convert (A >> B) & 1 to
	     A & (1 << B) allowing the bit mask to be hoisted out of the loop
	     saving an expensive shift.  */
	  if (pos == MOVE_POSSIBLE
	      && gimple_assign_rhs_code (stmt) == BIT_AND_EXPR
	      && integer_onep (op1)
	      && TREE_CODE (op0) == SSA_NAME
	      && has_single_use (op0))
	    stmt = rewrite_bittest (&bsi);
	}

      lim_data = init_lim_data (stmt);
      lim_data->always_executed_in = outermost;

      if (maybe_never && pos == MOVE_PRESERVE_EXECUTION)
	continue;

      if (!determine_max_movement (stmt, pos == MOVE_PRESERVE_EXECUTION))
	{
	  lim_data->max_loop = NULL;
	  continue;
	}

      if (dump_file && (dump_flags & TDF_DETAILS))
	{
	  print_gimple_stmt (dump_file, stmt, 2, 0);
	  fprintf (dump_file, "  invariant up to level %d, cost %d.\n\n",
		   loop_depth (lim_data->max_loop),
		   lim_data->cost);
	}

      if (lim_data->cost >= LIM_EXPENSIVE)
	set_profitable_level (stmt);
    }
}

class move_computations_dom_walker : public dom_walker
{
public:
  move_computations_dom_walker (cdi_direction direction)
    : dom_walker (direction), todo_ (0) {}

  virtual void before_dom_children (basic_block);

  unsigned int todo_;
};

/* Hoist the statements in basic block BB out of the loops prescribed by
   data stored in LIM_DATA structures associated with each statement.  Callback
   for walk_dominator_tree.  */

void
move_computations_dom_walker::before_dom_children (basic_block bb)
{
  struct loop *level;
  gimple_stmt_iterator bsi;
  gimple stmt;
  unsigned cost = 0;
  struct lim_aux_data *lim_data;

  if (!loop_outer (bb->loop_father))
    return;

  for (bsi = gsi_start_phis (bb); !gsi_end_p (bsi); )
    {
      gimple new_stmt;
      stmt = gsi_stmt (bsi);

      lim_data = get_lim_data (stmt);
      if (lim_data == NULL)
	{
	  gsi_next (&bsi);
	  continue;
	}

      cost = lim_data->cost;
      level = lim_data->tgt_loop;
      clear_lim_data (stmt);

      if (!level)
	{
	  gsi_next (&bsi);
	  continue;
	}

      if (dump_file && (dump_flags & TDF_DETAILS))
	{
	  fprintf (dump_file, "Moving PHI node\n");
	  print_gimple_stmt (dump_file, stmt, 0, 0);
	  fprintf (dump_file, "(cost %u) out of loop %d.\n\n",
		   cost, level->num);
	}

      if (gimple_phi_num_args (stmt) == 1)
	{
	  tree arg = PHI_ARG_DEF (stmt, 0);
	  new_stmt = gimple_build_assign_with_ops (TREE_CODE (arg),
						   gimple_phi_result (stmt),
						   arg, NULL_TREE);
	}
      else
	{
	  basic_block dom = get_immediate_dominator (CDI_DOMINATORS, bb);
	  gimple cond = gsi_stmt (gsi_last_bb (dom));
	  tree arg0 = NULL_TREE, arg1 = NULL_TREE, t;
	  /* Get the PHI arguments corresponding to the true and false
	     edges of COND.  */
	  extract_true_false_args_from_phi (dom, stmt, &arg0, &arg1);
	  gcc_assert (arg0 && arg1);
	  t = build2 (gimple_cond_code (cond), boolean_type_node,
		      gimple_cond_lhs (cond), gimple_cond_rhs (cond));
	  new_stmt = gimple_build_assign_with_ops (COND_EXPR,
						   gimple_phi_result (stmt),
						   t, arg0, arg1);
	  todo_ |= TODO_cleanup_cfg;
	}
      gsi_insert_on_edge (loop_preheader_edge (level), new_stmt);
      remove_phi_node (&bsi, false);
    }

  for (bsi = gsi_start_bb (bb); !gsi_end_p (bsi); )
    {
      edge e;

      stmt = gsi_stmt (bsi);

      lim_data = get_lim_data (stmt);
      if (lim_data == NULL)
	{
	  gsi_next (&bsi);
	  continue;
	}

      cost = lim_data->cost;
      level = lim_data->tgt_loop;
      clear_lim_data (stmt);

      if (!level)
	{
	  gsi_next (&bsi);
	  continue;
	}

      /* We do not really want to move conditionals out of the loop; we just
	 placed it here to force its operands to be moved if necessary.  */
      if (gimple_code (stmt) == GIMPLE_COND)
	continue;

      if (dump_file && (dump_flags & TDF_DETAILS))
	{
	  fprintf (dump_file, "Moving statement\n");
	  print_gimple_stmt (dump_file, stmt, 0, 0);
	  fprintf (dump_file, "(cost %u) out of loop %d.\n\n",
		   cost, level->num);
	}

      e = loop_preheader_edge (level);
      gcc_assert (!gimple_vdef (stmt));
      if (gimple_vuse (stmt))
	{
	  /* The new VUSE is the one from the virtual PHI in the loop
	     header or the one already present.  */
	  gimple_stmt_iterator gsi2;
	  for (gsi2 = gsi_start_phis (e->dest);
	       !gsi_end_p (gsi2); gsi_next (&gsi2))
	    {
	      gimple phi = gsi_stmt (gsi2);
	      if (virtual_operand_p (gimple_phi_result (phi)))
		{
		  gimple_set_vuse (stmt, PHI_ARG_DEF_FROM_EDGE (phi, e));
		  break;
		}
	    }
	}
      gsi_remove (&bsi, false);
      /* In case this is a stmt that is not unconditionally executed
         when the target loop header is executed and the stmt may
	 invoke undefined integer or pointer overflow rewrite it to
	 unsigned arithmetic.  */
      if (is_gimple_assign (stmt)
	  && INTEGRAL_TYPE_P (TREE_TYPE (gimple_assign_lhs (stmt)))
	  && TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (gimple_assign_lhs (stmt)))
	  && arith_code_with_undefined_signed_overflow
	       (gimple_assign_rhs_code (stmt))
	  && (!ALWAYS_EXECUTED_IN (bb)
	      || !(ALWAYS_EXECUTED_IN (bb) == level
		   || flow_loop_nested_p (ALWAYS_EXECUTED_IN (bb), level))))
	gsi_insert_seq_on_edge (e, rewrite_to_defined_overflow (stmt));
      else
	gsi_insert_on_edge (e, stmt);
    }
}

/* Hoist the statements out of the loops prescribed by data stored in
   LIM_DATA structures associated with each statement.*/

static unsigned int
move_computations (void)
{
  move_computations_dom_walker walker (CDI_DOMINATORS);
  walker.walk (cfun->cfg->x_entry_block_ptr);

  gsi_commit_edge_inserts ();
  if (need_ssa_update_p (cfun))
    rewrite_into_loop_closed_ssa (NULL, TODO_update_ssa);

  return walker.todo_;
}

/* Checks whether the statement defining variable *INDEX can be hoisted
   out of the loop passed in DATA.  Callback for for_each_index.  */

static bool
may_move_till (tree ref, tree *index, void *data)
{
  struct loop *loop = (struct loop *) data, *max_loop;

  /* If REF is an array reference, check also that the step and the lower
     bound is invariant in LOOP.  */
  if (TREE_CODE (ref) == ARRAY_REF)
    {
      tree step = TREE_OPERAND (ref, 3);
      tree lbound = TREE_OPERAND (ref, 2);

      max_loop = outermost_invariant_loop (step, loop);
      if (!max_loop)
	return false;

      max_loop = outermost_invariant_loop (lbound, loop);
      if (!max_loop)
	return false;
    }

  max_loop = outermost_invariant_loop (*index, loop);
  if (!max_loop)
    return false;

  return true;
}

/* If OP is SSA NAME, force the statement that defines it to be
   moved out of the LOOP.  ORIG_LOOP is the loop in that EXPR is used.  */

static void
force_move_till_op (tree op, struct loop *orig_loop, struct loop *loop)
{
  gimple stmt;

  if (!op
      || is_gimple_min_invariant (op))
    return;

  gcc_assert (TREE_CODE (op) == SSA_NAME);

  stmt = SSA_NAME_DEF_STMT (op);
  if (gimple_nop_p (stmt))
    return;

  set_level (stmt, orig_loop, loop);
}

/* Forces statement defining invariants in REF (and *INDEX) to be moved out of
   the LOOP.  The reference REF is used in the loop ORIG_LOOP.  Callback for
   for_each_index.  */

struct fmt_data
{
  struct loop *loop;
  struct loop *orig_loop;
};

static bool
force_move_till (tree ref, tree *index, void *data)
{
  struct fmt_data *fmt_data = (struct fmt_data *) data;

  if (TREE_CODE (ref) == ARRAY_REF)
    {
      tree step = TREE_OPERAND (ref, 3);
      tree lbound = TREE_OPERAND (ref, 2);

      force_move_till_op (step, fmt_data->orig_loop, fmt_data->loop);
      force_move_till_op (lbound, fmt_data->orig_loop, fmt_data->loop);
    }

  force_move_till_op (*index, fmt_data->orig_loop, fmt_data->loop);

  return true;
}

/* A function to free the mem_ref object OBJ.  */

static void
memref_free (struct im_mem_ref *mem)
{
  mem->accesses_in_loop.release ();
}

/* Allocates and returns a memory reference description for MEM whose hash
   value is HASH and id is ID.  */

static mem_ref_p
mem_ref_alloc (tree mem, unsigned hash, unsigned id)
{
  mem_ref_p ref = XOBNEW (&mem_ref_obstack, struct im_mem_ref);
  ao_ref_init (&ref->mem, mem);
  ref->id = id;
  ref->hash = hash;
  ref->stored = NULL;
  bitmap_initialize (&ref->indep_loop, &lim_bitmap_obstack);
  bitmap_initialize (&ref->dep_loop, &lim_bitmap_obstack);
  ref->accesses_in_loop.create (1);

  return ref;
}

/* Records memory reference location *LOC in LOOP to the memory reference
   description REF.  The reference occurs in statement STMT.  */

static void
record_mem_ref_loc (mem_ref_p ref, gimple stmt, tree *loc)
{
  mem_ref_loc aref;
  aref.stmt = stmt;
  aref.ref = loc;
  ref->accesses_in_loop.safe_push (aref);
}

/* Set the LOOP bit in REF stored bitmap and allocate that if
   necessary.  Return whether a bit was changed.  */

static bool
set_ref_stored_in_loop (mem_ref_p ref, struct loop *loop)
{
  if (!ref->stored)
    ref->stored = BITMAP_ALLOC (&lim_bitmap_obstack);
  return bitmap_set_bit (ref->stored, loop->num);
}

/* Marks reference REF as stored in LOOP.  */

static void
mark_ref_stored (mem_ref_p ref, struct loop *loop)
{
  while (loop != current_loops->tree_root
	 && set_ref_stored_in_loop (ref, loop))
    loop = loop_outer (loop);
}

/* Gathers memory references in statement STMT in LOOP, storing the
   information about them in the memory_accesses structure.  Marks
   the vops accessed through unrecognized statements there as
   well.  */

static void
gather_mem_refs_stmt (struct loop *loop, gimple stmt)
{
  tree *mem = NULL;
  hashval_t hash;
  im_mem_ref **slot;
  mem_ref_p ref;
  bool is_stored;
  unsigned id;

  if (!gimple_vuse (stmt))
    return;

  mem = simple_mem_ref_in_stmt (stmt, &is_stored);
  if (!mem)
    {
      /* We use the shared mem_ref for all unanalyzable refs.  */
      id = UNANALYZABLE_MEM_ID;
      ref = memory_accesses.refs_list[id];
      if (dump_file && (dump_flags & TDF_DETAILS))
	{
	  fprintf (dump_file, "Unanalyzed memory reference %u: ", id);
	  print_gimple_stmt (dump_file, stmt, 0, TDF_SLIM);
	}
      is_stored = gimple_vdef (stmt);
    }
  else
    {
      hash = iterative_hash_expr (*mem, 0);
      slot = memory_accesses.refs->find_slot_with_hash (*mem, hash, INSERT);
      if (*slot)
	{
	  ref = (mem_ref_p) *slot;
	  id = ref->id;
	}
      else
	{
	  id = memory_accesses.refs_list.length ();
	  ref = mem_ref_alloc (*mem, hash, id);
	  memory_accesses.refs_list.safe_push (ref);
	  *slot = ref;

	  if (dump_file && (dump_flags & TDF_DETAILS))
	    {
	      fprintf (dump_file, "Memory reference %u: ", id);
	      print_generic_expr (dump_file, ref->mem.ref, TDF_SLIM);
	      fprintf (dump_file, "\n");
	    }
	}

      record_mem_ref_loc (ref, stmt, mem);
    }
  bitmap_set_bit (&memory_accesses.refs_in_loop[loop->num], ref->id);
  if (is_stored)
    {
      bitmap_set_bit (&memory_accesses.refs_stored_in_loop[loop->num], ref->id);
      mark_ref_stored (ref, loop);
    }
  return;
}

static unsigned *bb_loop_postorder;

/* qsort sort function to sort blocks after their loop fathers postorder.  */

static int
sort_bbs_in_loop_postorder_cmp (const void *bb1_, const void *bb2_)
{
  basic_block bb1 = *(basic_block *)const_cast<void *>(bb1_);
  basic_block bb2 = *(basic_block *)const_cast<void *>(bb2_);
  struct loop *loop1 = bb1->loop_father;
  struct loop *loop2 = bb2->loop_father;
  if (loop1->num == loop2->num)
    return 0;
  return bb_loop_postorder[loop1->num] < bb_loop_postorder[loop2->num] ? -1 : 1;
}

/* qsort sort function to sort ref locs after their loop fathers postorder.  */

static int
sort_locs_in_loop_postorder_cmp (const void *loc1_, const void *loc2_)
{
  mem_ref_loc *loc1 = (mem_ref_loc *)const_cast<void *>(loc1_);
  mem_ref_loc *loc2 = (mem_ref_loc *)const_cast<void *>(loc2_);
  struct loop *loop1 = gimple_bb (loc1->stmt)->loop_father;
  struct loop *loop2 = gimple_bb (loc2->stmt)->loop_father;
  if (loop1->num == loop2->num)
    return 0;
  return bb_loop_postorder[loop1->num] < bb_loop_postorder[loop2->num] ? -1 : 1;
}

/* Gathers memory references in loops.  */

static void
analyze_memory_references (void)
{
  gimple_stmt_iterator bsi;
  basic_block bb, *bbs;
  struct loop *loop, *outer;
  unsigned i, n;

  /* Collect all basic-blocks in loops and sort them after their
     loops postorder.  */
  i = 0;
  bbs = XNEWVEC (basic_block, n_basic_blocks_for_fn (cfun) - NUM_FIXED_BLOCKS);
  FOR_EACH_BB_FN (bb, cfun)
    if (bb->loop_father != current_loops->tree_root)
      bbs[i++] = bb;
  n = i;
  qsort (bbs, n, sizeof (basic_block), sort_bbs_in_loop_postorder_cmp);

  /* Visit blocks in loop postorder and assign mem-ref IDs in that order.
     That results in better locality for all the bitmaps.  */
  for (i = 0; i < n; ++i)
    {
      basic_block bb = bbs[i];
      for (bsi = gsi_start_bb (bb); !gsi_end_p (bsi); gsi_next (&bsi))
        gather_mem_refs_stmt (bb->loop_father, gsi_stmt (bsi));
    }

  /* Sort the location list of gathered memory references after their
     loop postorder number.  */
  im_mem_ref *ref;
  FOR_EACH_VEC_ELT (memory_accesses.refs_list, i, ref)
    ref->accesses_in_loop.qsort (sort_locs_in_loop_postorder_cmp);

  free (bbs);
//  free (bb_loop_postorder);

  /* Propagate the information about accessed memory references up
     the loop hierarchy.  */
  FOR_EACH_LOOP (loop, LI_FROM_INNERMOST)
    {
      /* Finalize the overall touched references (including subloops).  */
      bitmap_ior_into (&memory_accesses.all_refs_stored_in_loop[loop->num],
		       &memory_accesses.refs_stored_in_loop[loop->num]);

      /* Propagate the information about accessed memory references up
	 the loop hierarchy.  */
      outer = loop_outer (loop);
      if (outer == current_loops->tree_root)
	continue;

      bitmap_ior_into (&memory_accesses.all_refs_stored_in_loop[outer->num],
		       &memory_accesses.all_refs_stored_in_loop[loop->num]);
    }
}

/* Returns true if MEM1 and MEM2 may alias.  TTAE_CACHE is used as a cache in
   tree_to_aff_combination_expand.  */

static bool
mem_refs_may_alias_p (mem_ref_p mem1, mem_ref_p mem2,
		      hash_map<tree, name_expansion *> **ttae_cache)
{
  /* Perform BASE + OFFSET analysis -- if MEM1 and MEM2 are based on the same
     object and their offset differ in such a way that the locations cannot
     overlap, then they cannot alias.  */
  widest_int size1, size2;
  aff_tree off1, off2;

  /* Perform basic offset and type-based disambiguation.  */
  if (!refs_may_alias_p_1 (&mem1->mem, &mem2->mem, true))
    return false;

  /* The expansion of addresses may be a bit expensive, thus we only do
     the check at -O2 and higher optimization levels.  */
  if (optimize < 2)
    return true;

  get_inner_reference_aff (mem1->mem.ref, &off1, &size1);
  get_inner_reference_aff (mem2->mem.ref, &off2, &size2);
  aff_combination_expand (&off1, ttae_cache);
  aff_combination_expand (&off2, ttae_cache);
  aff_combination_scale (&off1, -1);
  aff_combination_add (&off2, &off1);

  if (aff_comb_cannot_overlap_p (&off2, size1, size2))
    return false;

  return true;
}

/* Compare function for bsearch searching for reference locations
   in a loop.  */

static int
find_ref_loc_in_loop_cmp (const void *loop_, const void *loc_)
{
  struct loop *loop = (struct loop *)const_cast<void *>(loop_);
  mem_ref_loc *loc = (mem_ref_loc *)const_cast<void *>(loc_);
  struct loop *loc_loop = gimple_bb (loc->stmt)->loop_father;
  if (loop->num  == loc_loop->num
      || flow_loop_nested_p (loop, loc_loop))
    return 0;
  return (bb_loop_postorder[loop->num] < bb_loop_postorder[loc_loop->num]
	  ? -1 : 1);
}

/* Iterates over all locations of REF in LOOP and its subloops calling
   fn.operator() with the location as argument.  When that operator
   returns true the iteration is stopped and true is returned.
   Otherwise false is returned.  */

template <typename FN>
static bool
for_all_locs_in_loop (struct loop *loop, mem_ref_p ref, FN fn)
{
  unsigned i;
  mem_ref_loc_p loc;

  /* Search for the cluster of locs in the accesses_in_loop vector
     which is sorted after postorder index of the loop father.  */
  loc = ref->accesses_in_loop.bsearch (loop, find_ref_loc_in_loop_cmp);
  if (!loc)
    return false;

  /* We have found one location inside loop or its sub-loops.  Iterate
     both forward and backward to cover the whole cluster.  */
  i = loc - ref->accesses_in_loop.address ();
  while (i > 0)
    {
      --i;
      mem_ref_loc_p l = &ref->accesses_in_loop[i];
      if (!flow_bb_inside_loop_p (loop, gimple_bb (l->stmt)))
	break;
      if (fn (l))
	return true;
    }
  for (i = loc - ref->accesses_in_loop.address ();
       i < ref->accesses_in_loop.length (); ++i)
    {
      mem_ref_loc_p l = &ref->accesses_in_loop[i];
      if (!flow_bb_inside_loop_p (loop, gimple_bb (l->stmt)))
	break;
      if (fn (l))
	return true;
    }

  return false;
}

/* Rewrites location LOC by TMP_VAR.  */

struct rewrite_mem_ref_loc
{
  rewrite_mem_ref_loc (tree tmp_var_) : tmp_var (tmp_var_) {}
  bool operator () (mem_ref_loc_p loc);
  tree tmp_var;
};

bool
rewrite_mem_ref_loc::operator () (mem_ref_loc_p loc)
{
  *loc->ref = tmp_var;
  update_stmt (loc->stmt);
  return false;
}

/* Rewrites all references to REF in LOOP by variable TMP_VAR.  */

static void
rewrite_mem_refs (struct loop *loop, mem_ref_p ref, tree tmp_var)
{
  for_all_locs_in_loop (loop, ref, rewrite_mem_ref_loc (tmp_var));
}

/* Stores the first reference location in LOCP.  */

struct first_mem_ref_loc_1
{
  first_mem_ref_loc_1 (mem_ref_loc_p *locp_) : locp (locp_) {}
  bool operator () (mem_ref_loc_p loc);
  mem_ref_loc_p *locp;
};

bool
first_mem_ref_loc_1::operator () (mem_ref_loc_p loc)
{
  *locp = loc;
  return true;
}

/* Returns the first reference location to REF in LOOP.  */

static mem_ref_loc_p
first_mem_ref_loc (struct loop *loop, mem_ref_p ref)
{
  mem_ref_loc_p locp = NULL;
  for_all_locs_in_loop (loop, ref, first_mem_ref_loc_1 (&locp));
  return locp;
}

struct prev_flag_edges {
  /* Edge to insert new flag comparison code.  */
  edge append_cond_position;

  /* Edge for fall through from previous flag comparison.  */
  edge last_cond_fallthru;
};

/* Helper function for execute_sm.  Emit code to store TMP_VAR into
   MEM along edge EX.

   The store is only done if MEM has changed.  We do this so no
   changes to MEM occur on code paths that did not originally store
   into it.

   The common case for execute_sm will transform:

     for (...) {
       if (foo)
         stuff;
       else
         MEM = TMP_VAR;
     }

   into:

     lsm = MEM;
     for (...) {
       if (foo)
         stuff;
       else
         lsm = TMP_VAR;
     }
     MEM = lsm;

  This function will generate:

     lsm = MEM;

     lsm_flag = false;
     ...
     for (...) {
       if (foo)
         stuff;
       else {
         lsm = TMP_VAR;
         lsm_flag = true;
       }
     }
     if (lsm_flag)	<--
       MEM = lsm;	<--
*/

static void
execute_sm_if_changed (edge ex, tree mem, tree tmp_var, tree flag)
{
  basic_block new_bb, then_bb, old_dest;
  bool loop_has_only_one_exit;
  edge then_old_edge, orig_ex = ex;
  gimple_stmt_iterator gsi;
  gimple stmt;
  struct prev_flag_edges *prev_edges = (struct prev_flag_edges *) ex->aux;
  bool irr = ex->flags & EDGE_IRREDUCIBLE_LOOP;

  /* ?? Insert store after previous store if applicable.  See note
     below.  */
  if (prev_edges)
    ex = prev_edges->append_cond_position;

  loop_has_only_one_exit = single_pred_p (ex->dest);

  if (loop_has_only_one_exit)
    ex = split_block_after_labels (ex->dest);

  old_dest = ex->dest;
  new_bb = split_edge (ex);
  then_bb = create_empty_bb (new_bb);
  if (irr)
    then_bb->flags = BB_IRREDUCIBLE_LOOP;
  add_bb_to_loop (then_bb, new_bb->loop_father);

  gsi = gsi_start_bb (new_bb);
  stmt = gimple_build_cond (NE_EXPR, flag, boolean_false_node,
			    NULL_TREE, NULL_TREE);
  gsi_insert_after (&gsi, stmt, GSI_CONTINUE_LINKING);

  gsi = gsi_start_bb (then_bb);
  /* Insert actual store.  */
  stmt = gimple_build_assign (unshare_expr (mem), tmp_var);
  gsi_insert_after (&gsi, stmt, GSI_CONTINUE_LINKING);

  make_edge (new_bb, then_bb,
	     EDGE_TRUE_VALUE | (irr ? EDGE_IRREDUCIBLE_LOOP : 0));
  make_edge (new_bb, old_dest,
	     EDGE_FALSE_VALUE | (irr ? EDGE_IRREDUCIBLE_LOOP : 0));
  then_old_edge = make_edge (then_bb, old_dest,
			     EDGE_FALLTHRU | (irr ? EDGE_IRREDUCIBLE_LOOP : 0));

  set_immediate_dominator (CDI_DOMINATORS, then_bb, new_bb);

  if (prev_edges)
    {
      basic_block prevbb = prev_edges->last_cond_fallthru->src;
      redirect_edge_succ (prev_edges->last_cond_fallthru, new_bb);
      set_immediate_dominator (CDI_DOMINATORS, new_bb, prevbb);
      set_immediate_dominator (CDI_DOMINATORS, old_dest,
			       recompute_dominator (CDI_DOMINATORS, old_dest));
    }

  /* ?? Because stores may alias, they must happen in the exact
     sequence they originally happened.  Save the position right after
     the (_lsm) store we just created so we can continue appending after
     it and maintain the original order.  */
  {
    struct prev_flag_edges *p;

    if (orig_ex->aux)
      orig_ex->aux = NULL;
    alloc_aux_for_edge (orig_ex, sizeof (struct prev_flag_edges));
    p = (struct prev_flag_edges *) orig_ex->aux;
    p->append_cond_position = then_old_edge;
    p->last_cond_fallthru = find_edge (new_bb, old_dest);
    orig_ex->aux = (void *) p;
  }

  if (!loop_has_only_one_exit)
    for (gsi = gsi_start_phis (old_dest); !gsi_end_p (gsi); gsi_next (&gsi))
      {
	gimple phi = gsi_stmt (gsi);
	unsigned i;

	for (i = 0; i < gimple_phi_num_args (phi); i++)
	  if (gimple_phi_arg_edge (phi, i)->src == new_bb)
	    {
	      tree arg = gimple_phi_arg_def (phi, i);
	      add_phi_arg (phi, arg, then_old_edge, UNKNOWN_LOCATION);
	      update_stmt (phi);
	    }
      }
  /* Remove the original fall through edge.  This was the
     single_succ_edge (new_bb).  */
  EDGE_SUCC (new_bb, 0)->flags &= ~EDGE_FALLTHRU;
}

/* When REF is set on the location, set flag indicating the store.  */

struct sm_set_flag_if_changed
{
  sm_set_flag_if_changed (tree flag_) : flag (flag_) {}
  bool operator () (mem_ref_loc_p loc);
  tree flag;
};

bool
sm_set_flag_if_changed::operator () (mem_ref_loc_p loc)
{
  /* Only set the flag for writes.  */
  if (is_gimple_assign (loc->stmt)
      && gimple_assign_lhs_ptr (loc->stmt) == loc->ref)
    {
      gimple_stmt_iterator gsi = gsi_for_stmt (loc->stmt);
      gimple stmt = gimple_build_assign (flag, boolean_true_node);
      gsi_insert_after (&gsi, stmt, GSI_CONTINUE_LINKING);
    }
  return false;
}

/* Helper function for execute_sm.  On every location where REF is
   set, set an appropriate flag indicating the store.  */

static tree
execute_sm_if_changed_flag_set (struct loop *loop, mem_ref_p ref)
{
  tree flag;
  char *str = get_lsm_tmp_name (ref->mem.ref, ~0, "_flag");
  flag = create_tmp_reg (boolean_type_node, str);
  for_all_locs_in_loop (loop, ref, sm_set_flag_if_changed (flag));
  return flag;
}

/* Executes store motion of memory reference REF from LOOP.
   Exits from the LOOP are stored in EXITS.  The initialization of the
   temporary variable is put to the preheader of the loop, and assignments
   to the reference from the temporary variable are emitted to exits.  */

static void
execute_sm (struct loop *loop, vec<edge> exits, mem_ref_p ref)
{
  tree tmp_var, store_flag = NULL_TREE;
  unsigned i;
  gimple load;
  struct fmt_data fmt_data;
  edge ex;
  struct lim_aux_data *lim_data;
  bool multi_threaded_model_p = false;
  gimple_stmt_iterator gsi;

  if (dump_file && (dump_flags & TDF_DETAILS))
    {
      fprintf (dump_file, "Executing store motion of ");
      print_generic_expr (dump_file, ref->mem.ref, 0);
      fprintf (dump_file, " from loop %d\n", loop->num);
    }

  tmp_var = create_tmp_reg (TREE_TYPE (ref->mem.ref),
			    get_lsm_tmp_name (ref->mem.ref, ~0));

  fmt_data.loop = loop;
  fmt_data.orig_loop = loop;
  for_each_index (&ref->mem.ref, force_move_till, &fmt_data);

  if (bb_in_transaction (loop_preheader_edge (loop)->src)
      || !PARAM_VALUE (PARAM_ALLOW_STORE_DATA_RACES))
    multi_threaded_model_p = true;

  if (multi_threaded_model_p)
    store_flag = execute_sm_if_changed_flag_set (loop, ref);

  rewrite_mem_refs (loop, ref, tmp_var);

  /* Emit the load code on a random exit edge or into the latch if
     the loop does not exit, so that we are sure it will be processed
     by move_computations after all dependencies.  */
  gsi = gsi_for_stmt (first_mem_ref_loc (loop, ref)->stmt);

  /* FIXME/TODO: For the multi-threaded variant, we could avoid this
     load altogether, since the store is predicated by a flag.  We
     could, do the load only if it was originally in the loop.  */
  load = gimple_build_assign (tmp_var, unshare_expr (ref->mem.ref));
  lim_data = init_lim_data (load);
  lim_data->max_loop = loop;
  lim_data->tgt_loop = loop;
  gsi_insert_before (&gsi, load, GSI_SAME_STMT);

  if (multi_threaded_model_p)
    {
      load = gimple_build_assign (store_flag, boolean_false_node);
      lim_data = init_lim_data (load);
      lim_data->max_loop = loop;
      lim_data->tgt_loop = loop;
      gsi_insert_before (&gsi, load, GSI_SAME_STMT);
    }

  /* Sink the store to every exit from the loop.  */
  FOR_EACH_VEC_ELT (exits, i, ex)
    if (!multi_threaded_model_p)
      {
	gimple store;
	store = gimple_build_assign (unshare_expr (ref->mem.ref), tmp_var);
	gsi_insert_on_edge (ex, store);
      }
    else
      execute_sm_if_changed (ex, ref->mem.ref, tmp_var, store_flag);
}

/* Hoists memory references MEM_REFS out of LOOP.  EXITS is the list of exit
   edges of the LOOP.  */

static void
hoist_memory_references (struct loop *loop, bitmap mem_refs,
			 vec<edge> exits)
{
  mem_ref_p ref;
  unsigned  i;
  bitmap_iterator bi;

  EXECUTE_IF_SET_IN_BITMAP (mem_refs, 0, i, bi)
    {
      ref = memory_accesses.refs_list[i];
      execute_sm (loop, exits, ref);
    }
}

struct ref_always_accessed
{
  ref_always_accessed (struct loop *loop_, bool stored_p_)
      : loop (loop_), stored_p (stored_p_) {}
  bool operator () (mem_ref_loc_p loc);
  struct loop *loop;
  bool stored_p;
};

bool
ref_always_accessed::operator () (mem_ref_loc_p loc)
{
  struct loop *must_exec;

  if (!get_lim_data (loc->stmt))
    return false;

  /* If we require an always executed store make sure the statement
     stores to the reference.  */
  if (stored_p)
    {
      tree lhs = gimple_get_lhs (loc->stmt);
      if (!lhs
	  || lhs != *loc->ref)
	return false;
    }

  must_exec = get_lim_data (loc->stmt)->always_executed_in;
  if (!must_exec)
    return false;

  if (must_exec == loop
      || flow_loop_nested_p (must_exec, loop))
    return true;

  return false;
}

/* Returns true if REF is always accessed in LOOP.  If STORED_P is true
   make sure REF is always stored to in LOOP.  */

static bool
ref_always_accessed_p (struct loop *loop, mem_ref_p ref, bool stored_p)
{
  return for_all_locs_in_loop (loop, ref,
			       ref_always_accessed (loop, stored_p));
}

/* Returns true if REF1 and REF2 are independent.  */

static bool
refs_independent_p (mem_ref_p ref1, mem_ref_p ref2)
{
  if (ref1 == ref2)
    return true;

  if (dump_file && (dump_flags & TDF_DETAILS))
    fprintf (dump_file, "Querying dependency of refs %u and %u: ",
	     ref1->id, ref2->id);

  if (mem_refs_may_alias_p (ref1, ref2, &memory_accesses.ttae_cache))
    {
      if (dump_file && (dump_flags & TDF_DETAILS))
	fprintf (dump_file, "dependent.\n");
      return false;
    }
  else
    {
      if (dump_file && (dump_flags & TDF_DETAILS))
	fprintf (dump_file, "independent.\n");
      return true;
    }
}

/* Mark REF dependent on stores or loads (according to STORED_P) in LOOP
   and its super-loops.  */

static void
record_dep_loop (struct loop *loop, mem_ref_p ref, bool stored_p)
{
  /* We can propagate dependent-in-loop bits up the loop
     hierarchy to all outer loops.  */
  while (loop != current_loops->tree_root
	 && bitmap_set_bit (&ref->dep_loop, LOOP_DEP_BIT (loop->num, stored_p)))
    loop = loop_outer (loop);
}

/* Returns true if REF is independent on all other memory references in
   LOOP.  */

static bool
ref_indep_loop_p_1 (struct loop *loop, mem_ref_p ref, bool stored_p)
{
  bitmap refs_to_check;
  unsigned i;
  bitmap_iterator bi;
  mem_ref_p aref;

  if (stored_p)
    refs_to_check = &memory_accesses.refs_in_loop[loop->num];
  else
    refs_to_check = &memory_accesses.refs_stored_in_loop[loop->num];

  if (bitmap_bit_p (refs_to_check, UNANALYZABLE_MEM_ID))
    return false;

  EXECUTE_IF_SET_IN_BITMAP (refs_to_check, 0, i, bi)
    {
      aref = memory_accesses.refs_list[i];
      if (!refs_independent_p (ref, aref))
	return false;
    }

  return true;
}

/* Returns true if REF is independent on all other memory references in
   LOOP.  Wrapper over ref_indep_loop_p_1, caching its results.  */

static bool
ref_indep_loop_p_2 (struct loop *loop, mem_ref_p ref, bool stored_p)
{
  stored_p |= (ref->stored && bitmap_bit_p (ref->stored, loop->num));

  if (bitmap_bit_p (&ref->indep_loop, LOOP_DEP_BIT (loop->num, stored_p)))
    return true;
  if (bitmap_bit_p (&ref->dep_loop, LOOP_DEP_BIT (loop->num, stored_p)))
    return false;

  struct loop *inner = loop->inner;
  while (inner)
    {
      if (!ref_indep_loop_p_2 (inner, ref, stored_p))
	return false;
      inner = inner->next;
    }

  bool indep_p = ref_indep_loop_p_1 (loop, ref, stored_p);

  if (dump_file && (dump_flags & TDF_DETAILS))
    fprintf (dump_file, "Querying dependencies of ref %u in loop %d: %s\n",
	     ref->id, loop->num, indep_p ? "independent" : "dependent");

  /* Record the computed result in the cache.  */
  if (indep_p)
    {
      if (bitmap_set_bit (&ref->indep_loop, LOOP_DEP_BIT (loop->num, stored_p))
	  && stored_p)
	{
	  /* If it's independend against all refs then it's independent
	     against stores, too.  */
	  bitmap_set_bit (&ref->indep_loop, LOOP_DEP_BIT (loop->num, false));
	}
    }
  else
    {
      record_dep_loop (loop, ref, stored_p);
      if (!stored_p)
	{
	  /* If it's dependent against stores it's dependent against
	     all refs, too.  */
	  record_dep_loop (loop, ref, true);
	}
    }

  return indep_p;
}

/* Returns true if REF is independent on all other memory references in
   LOOP.  */

static bool
ref_indep_loop_p (struct loop *loop, mem_ref_p ref)
{
  gcc_checking_assert (MEM_ANALYZABLE (ref));

  return ref_indep_loop_p_2 (loop, ref, false);
}

/* Returns true if we can perform store motion of REF from LOOP.  */

static bool
can_sm_ref_p (struct loop *loop, mem_ref_p ref)
{
  tree base;

  /* Can't hoist unanalyzable refs.  */
  if (!MEM_ANALYZABLE (ref))
    return false;

  /* It should be movable.  */
  if (!is_gimple_reg_type (TREE_TYPE (ref->mem.ref))
      || TREE_THIS_VOLATILE (ref->mem.ref)
      || !for_each_index (&ref->mem.ref, may_move_till, loop))
    return false;

  /* If it can throw fail, we do not properly update EH info.  */
  if (tree_could_throw_p (ref->mem.ref))
    return false;

  /* If it can trap, it must be always executed in LOOP.
     Readonly memory locations may trap when storing to them, but
     tree_could_trap_p is a predicate for rvalues, so check that
     explicitly.  */
  base = get_base_address (ref->mem.ref);
  if ((tree_could_trap_p (ref->mem.ref)
       || (DECL_P (base) && TREE_READONLY (base)))
      && !ref_always_accessed_p (loop, ref, true))
    return false;

  /* And it must be independent on all other memory references
     in LOOP.  */
  if (!ref_indep_loop_p (loop, ref))
    return false;

  return true;
}

/* Marks the references in LOOP for that store motion should be performed
   in REFS_TO_SM.  SM_EXECUTED is the set of references for that store
   motion was performed in one of the outer loops.  */

static void
find_refs_for_sm (struct loop *loop, bitmap sm_executed, bitmap refs_to_sm)
{
  bitmap refs = &memory_accesses.all_refs_stored_in_loop[loop->num];
  unsigned i;
  bitmap_iterator bi;
  mem_ref_p ref;

  EXECUTE_IF_AND_COMPL_IN_BITMAP (refs, sm_executed, 0, i, bi)
    {
      ref = memory_accesses.refs_list[i];
      if (can_sm_ref_p (loop, ref))
	bitmap_set_bit (refs_to_sm, i);
    }
}

/* Checks whether LOOP (with exits stored in EXITS array) is suitable
   for a store motion optimization (i.e. whether we can insert statement
   on its exits).  */

static bool
loop_suitable_for_sm (struct loop *loop ATTRIBUTE_UNUSED,
		      vec<edge> exits)
{
  unsigned i;
  edge ex;

  FOR_EACH_VEC_ELT (exits, i, ex)
    if (ex->flags & (EDGE_ABNORMAL | EDGE_EH))
      return false;

  return true;
}

/* Try to perform store motion for all memory references modified inside
   LOOP.  SM_EXECUTED is the bitmap of the memory references for that
   store motion was executed in one of the outer loops.  */

static void
store_motion_loop (struct loop *loop, bitmap sm_executed)
{
  vec<edge> exits = get_loop_exit_edges (loop);
  struct loop *subloop;
  bitmap sm_in_loop = BITMAP_ALLOC (&lim_bitmap_obstack);

  if (loop_suitable_for_sm (loop, exits))
    {
      find_refs_for_sm (loop, sm_executed, sm_in_loop);
      hoist_memory_references (loop, sm_in_loop, exits);
    }
  exits.release ();

  bitmap_ior_into (sm_executed, sm_in_loop);
  for (subloop = loop->inner; subloop != NULL; subloop = subloop->next)
    store_motion_loop (subloop, sm_executed);
  bitmap_and_compl_into (sm_executed, sm_in_loop);
  BITMAP_FREE (sm_in_loop);
}

/* Try to perform store motion for all memory references modified inside
   loops.  */

static void
store_motion (void)
{
  struct loop *loop;
  bitmap sm_executed = BITMAP_ALLOC (&lim_bitmap_obstack);

  for (loop = current_loops->tree_root->inner; loop != NULL; loop = loop->next)
    store_motion_loop (loop, sm_executed);

  BITMAP_FREE (sm_executed);
  gsi_commit_edge_inserts ();
}

/* Fills ALWAYS_EXECUTED_IN information for basic blocks of LOOP, i.e.
   for each such basic block bb records the outermost loop for that execution
   of its header implies execution of bb.  CONTAINS_CALL is the bitmap of
   blocks that contain a nonpure call.  */

static void
fill_always_executed_in_1 (struct loop *loop, sbitmap contains_call)
{
  basic_block bb = NULL, *bbs, last = NULL;
  unsigned i;
  edge e;
  struct loop *inn_loop = loop;

  if (ALWAYS_EXECUTED_IN (loop->header) == NULL)
    {
      bbs = get_loop_body_in_dom_order (loop);

      for (i = 0; i < loop->num_nodes; i++)
	{
	  edge_iterator ei;
	  bb = bbs[i];

	  if (dominated_by_p (CDI_DOMINATORS, loop->latch, bb))
	    last = bb;

	  if (bitmap_bit_p (contains_call, bb->index))
	    break;

	  FOR_EACH_EDGE (e, ei, bb->succs)
	    if (!flow_bb_inside_loop_p (loop, e->dest))
	      break;
	  if (e)
	    break;

	  /* A loop might be infinite (TODO use simple loop analysis
	     to disprove this if possible).  */
	  if (bb->flags & BB_IRREDUCIBLE_LOOP)
	    break;

	  if (!flow_bb_inside_loop_p (inn_loop, bb))
	    break;

	  if (bb->loop_father->header == bb)
	    {
	      if (!dominated_by_p (CDI_DOMINATORS, loop->latch, bb))
		break;

	      /* In a loop that is always entered we may proceed anyway.
		 But record that we entered it and stop once we leave it.  */
	      inn_loop = bb->loop_father;
	    }
	}

      while (1)
	{
	  SET_ALWAYS_EXECUTED_IN (last, loop);
	  if (last == loop->header)
	    break;
	  last = get_immediate_dominator (CDI_DOMINATORS, last);
	}

      free (bbs);
    }

  for (loop = loop->inner; loop; loop = loop->next)
    fill_always_executed_in_1 (loop, contains_call);
}

/* Fills ALWAYS_EXECUTED_IN information for basic blocks, i.e.
   for each such basic block bb records the outermost loop for that execution
   of its header implies execution of bb.  */

static void
fill_always_executed_in (void)
{
  sbitmap contains_call = sbitmap_alloc (last_basic_block_for_fn (cfun));
  basic_block bb;
  struct loop *loop;

  bitmap_clear (contains_call);
  FOR_EACH_BB_FN (bb, cfun)
    {
      gimple_stmt_iterator gsi;
      for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
	{
	  if (nonpure_call_p (gsi_stmt (gsi)))
	    break;
	}

      if (!gsi_end_p (gsi))
	bitmap_set_bit (contains_call, bb->index);
    }

  for (loop = current_loops->tree_root->inner; loop; loop = loop->next)
    fill_always_executed_in_1 (loop, contains_call);

  sbitmap_free (contains_call);
}


/* Compute the global information needed by the loop invariant motion pass.  */

static void
tree_ssa_lim_initialize (void)
{
  struct loop *loop;
  unsigned i;

  bitmap_obstack_initialize (&lim_bitmap_obstack);
  gcc_obstack_init (&mem_ref_obstack);
  lim_aux_data_map = new hash_map<gimple, lim_aux_data *>;

  if (flag_tm)
    compute_transaction_bits ();

  alloc_aux_for_edges (0);

  memory_accesses.refs = new hash_table<mem_ref_hasher> (100);
  memory_accesses.refs_list.create (100);
  /* Allocate a special, unanalyzable mem-ref with ID zero.  */
  memory_accesses.refs_list.quick_push
    (mem_ref_alloc (error_mark_node, 0, UNANALYZABLE_MEM_ID));

  memory_accesses.refs_in_loop.create (number_of_loops (cfun));
  memory_accesses.refs_in_loop.quick_grow (number_of_loops (cfun));
  memory_accesses.refs_stored_in_loop.create (number_of_loops (cfun));
  memory_accesses.refs_stored_in_loop.quick_grow (number_of_loops (cfun));
  memory_accesses.all_refs_stored_in_loop.create (number_of_loops (cfun));
  memory_accesses.all_refs_stored_in_loop.quick_grow (number_of_loops (cfun));

  for (i = 0; i < number_of_loops (cfun); i++)
    {
      bitmap_initialize (&memory_accesses.refs_in_loop[i],
			 &lim_bitmap_obstack);
      bitmap_initialize (&memory_accesses.refs_stored_in_loop[i],
			 &lim_bitmap_obstack);
      bitmap_initialize (&memory_accesses.all_refs_stored_in_loop[i],
			 &lim_bitmap_obstack);
    }

  memory_accesses.ttae_cache = NULL;

  /* Initialize bb_loop_postorder with a mapping from loop->num to
     its postorder index.  */
  i = 0;
  bb_loop_postorder = XNEWVEC (unsigned, number_of_loops (cfun));
  FOR_EACH_LOOP (loop, LI_FROM_INNERMOST)
    bb_loop_postorder[loop->num] = i++;
}

/* Cleans up after the invariant motion pass.  */

static void
tree_ssa_lim_finalize (void)
{
  basic_block bb;
  unsigned i;
  mem_ref_p ref;

  free_aux_for_edges ();

  FOR_EACH_BB_FN (bb, cfun)
    SET_ALWAYS_EXECUTED_IN (bb, NULL);

  bitmap_obstack_release (&lim_bitmap_obstack);
  delete lim_aux_data_map;

  delete memory_accesses.refs;
  memory_accesses.refs = NULL;

  FOR_EACH_VEC_ELT (memory_accesses.refs_list, i, ref)
    memref_free (ref);
  memory_accesses.refs_list.release ();
  obstack_free (&mem_ref_obstack, NULL);

  memory_accesses.refs_in_loop.release ();
  memory_accesses.refs_stored_in_loop.release ();
  memory_accesses.all_refs_stored_in_loop.release ();

  if (memory_accesses.ttae_cache)
    free_affine_expand_cache (&memory_accesses.ttae_cache);

  free (bb_loop_postorder);
}

/* Moves invariants from loops.  Only "expensive" invariants are moved out --
   i.e. those that are likely to be win regardless of the register pressure.  */

unsigned int
tree_ssa_lim (void)
{
  unsigned int todo;

  tree_ssa_lim_initialize ();

  /* Gathers information about memory accesses in the loops.  */
  analyze_memory_references ();

  /* Fills ALWAYS_EXECUTED_IN information for basic blocks.  */
  fill_always_executed_in ();

  /* For each statement determine the outermost loop in that it is
     invariant and cost for computing the invariant.  */
  invariantness_dom_walker (CDI_DOMINATORS)
    .walk (cfun->cfg->x_entry_block_ptr);

  /* Execute store motion.  Force the necessary invariants to be moved
     out of the loops as well.  */
  store_motion ();

  /* Move the expressions that are expensive enough.  */
  todo = move_computations ();

  tree_ssa_lim_finalize ();

  return todo;
}

/* Loop invariant motion pass.  */

namespace {

const pass_data pass_data_lim =
{
  GIMPLE_PASS, /* type */
  "lim", /* name */
  OPTGROUP_LOOP, /* optinfo_flags */
  TV_LIM, /* tv_id */
  PROP_cfg, /* properties_required */
  0, /* properties_provided */
  0, /* properties_destroyed */
  0, /* todo_flags_start */
  0, /* todo_flags_finish */
};

class pass_lim : public gimple_opt_pass
{
public:
  pass_lim (gcc::context *ctxt)
    : gimple_opt_pass (pass_data_lim, ctxt)
  {}

  /* opt_pass methods: */
  opt_pass * clone () { return new pass_lim (m_ctxt); }
  virtual bool gate (function *) { return flag_tree_loop_im != 0; }
  virtual unsigned int execute (function *);

}; // class pass_lim

unsigned int
pass_lim::execute (function *fun)
{
  if (number_of_loops (fun) <= 1)
    return 0;

  return tree_ssa_lim ();
}

} // anon namespace

gimple_opt_pass *
make_pass_lim (gcc::context *ctxt)
{
  return new pass_lim (ctxt);
}