summaryrefslogtreecommitdiff
path: root/gcc/cselib.c
blob: a35dca8d79e458e65df3663f9d741de2f9cc6bce (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
2600
2601
2602
2603
2604
2605
2606
2607
2608
2609
2610
2611
2612
2613
2614
2615
2616
2617
2618
2619
2620
2621
2622
2623
2624
2625
2626
2627
2628
2629
2630
2631
2632
2633
2634
2635
2636
2637
2638
2639
2640
2641
2642
2643
2644
2645
2646
2647
2648
2649
2650
2651
2652
2653
2654
2655
2656
2657
2658
2659
2660
2661
2662
2663
2664
2665
2666
2667
2668
2669
2670
2671
2672
2673
2674
2675
2676
2677
2678
2679
2680
2681
2682
2683
2684
2685
2686
2687
2688
2689
2690
2691
2692
2693
2694
2695
2696
2697
2698
2699
2700
2701
2702
2703
2704
2705
2706
2707
2708
2709
2710
2711
2712
2713
2714
2715
2716
2717
2718
2719
2720
2721
2722
2723
2724
2725
2726
2727
2728
2729
2730
2731
2732
2733
2734
2735
2736
2737
2738
2739
2740
2741
2742
2743
2744
2745
2746
2747
2748
2749
2750
2751
2752
2753
2754
2755
2756
2757
2758
2759
2760
2761
2762
2763
2764
2765
2766
2767
2768
2769
2770
2771
2772
2773
2774
2775
2776
2777
2778
2779
2780
2781
2782
2783
2784
2785
2786
2787
2788
2789
2790
2791
2792
2793
2794
2795
2796
2797
2798
2799
2800
2801
2802
2803
2804
2805
2806
2807
2808
2809
2810
2811
2812
2813
2814
2815
2816
2817
2818
2819
2820
2821
2822
2823
2824
2825
2826
2827
2828
2829
2830
2831
2832
2833
2834
2835
2836
2837
2838
2839
2840
2841
2842
2843
2844
2845
2846
2847
2848
2849
2850
2851
2852
2853
2854
2855
2856
2857
2858
2859
2860
2861
2862
2863
2864
2865
2866
/* Common subexpression elimination library for GNU compiler.
   Copyright (C) 1987-2016 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 "backend.h"
#include "target.h"
#include "rtl.h"
#include "tree.h"
#include "df.h"
#include "memmodel.h"
#include "tm_p.h"
#include "regs.h"
#include "emit-rtl.h"
#include "dumpfile.h"
#include "cselib.h"
#include "params.h"

/* A list of cselib_val structures.  */
struct elt_list
{
  struct elt_list *next;
  cselib_val *elt;
};

static bool cselib_record_memory;
static bool cselib_preserve_constants;
static bool cselib_any_perm_equivs;
static inline void promote_debug_loc (struct elt_loc_list *l);
static struct elt_list *new_elt_list (struct elt_list *, cselib_val *);
static void new_elt_loc_list (cselib_val *, rtx);
static void unchain_one_value (cselib_val *);
static void unchain_one_elt_list (struct elt_list **);
static void unchain_one_elt_loc_list (struct elt_loc_list **);
static void remove_useless_values (void);
static unsigned int cselib_hash_rtx (rtx, int, machine_mode);
static cselib_val *new_cselib_val (unsigned int, machine_mode, rtx);
static void add_mem_for_addr (cselib_val *, cselib_val *, rtx);
static cselib_val *cselib_lookup_mem (rtx, int);
static void cselib_invalidate_regno (unsigned int, machine_mode);
static void cselib_invalidate_mem (rtx);
static void cselib_record_set (rtx, cselib_val *, cselib_val *);
static void cselib_record_sets (rtx_insn *);

struct expand_value_data
{
  bitmap regs_active;
  cselib_expand_callback callback;
  void *callback_arg;
  bool dummy;
};

static rtx cselib_expand_value_rtx_1 (rtx, struct expand_value_data *, int);

/* There are three ways in which cselib can look up an rtx:
   - for a REG, the reg_values table (which is indexed by regno) is used
   - for a MEM, we recursively look up its address and then follow the
     addr_list of that value
   - for everything else, we compute a hash value and go through the hash
     table.  Since different rtx's can still have the same hash value,
     this involves walking the table entries for a given value and comparing
     the locations of the entries with the rtx we are looking up.  */

struct cselib_hasher : nofree_ptr_hash <cselib_val>
{
  struct key {
    /* The rtx value and its mode (needed separately for constant
       integers).  */
    machine_mode mode;
    rtx x;
    /* The mode of the contaning MEM, if any, otherwise VOIDmode.  */
    machine_mode memmode;
  };
  typedef key *compare_type;
  static inline hashval_t hash (const cselib_val *);
  static inline bool equal (const cselib_val *, const key *);
};

/* The hash function for our hash table.  The value is always computed with
   cselib_hash_rtx when adding an element; this function just extracts the
   hash value from a cselib_val structure.  */

inline hashval_t
cselib_hasher::hash (const cselib_val *v)
{
  return v->hash;
}

/* The equality test for our hash table.  The first argument V is a table
   element (i.e. a cselib_val), while the second arg X is an rtx.  We know
   that all callers of htab_find_slot_with_hash will wrap CONST_INTs into a
   CONST of an appropriate mode.  */

inline bool
cselib_hasher::equal (const cselib_val *v, const key *x_arg)
{
  struct elt_loc_list *l;
  rtx x = x_arg->x;
  machine_mode mode = x_arg->mode;
  machine_mode memmode = x_arg->memmode;

  if (mode != GET_MODE (v->val_rtx))
    return false;

  if (GET_CODE (x) == VALUE)
    return x == v->val_rtx;

  /* We don't guarantee that distinct rtx's have different hash values,
     so we need to do a comparison.  */
  for (l = v->locs; l; l = l->next)
    if (rtx_equal_for_cselib_1 (l->loc, x, memmode))
      {
	promote_debug_loc (l);
	return true;
      }

  return false;
}

/* A table that enables us to look up elts by their value.  */
static hash_table<cselib_hasher> *cselib_hash_table;

/* A table to hold preserved values.  */
static hash_table<cselib_hasher> *cselib_preserved_hash_table;

/* This is a global so we don't have to pass this through every function.
   It is used in new_elt_loc_list to set SETTING_INSN.  */
static rtx_insn *cselib_current_insn;

/* The unique id that the next create value will take.  */
static unsigned int next_uid;

/* The number of registers we had when the varrays were last resized.  */
static unsigned int cselib_nregs;

/* Count values without known locations, or with only locations that
   wouldn't have been known except for debug insns.  Whenever this
   grows too big, we remove these useless values from the table.

   Counting values with only debug values is a bit tricky.  We don't
   want to increment n_useless_values when we create a value for a
   debug insn, for this would get n_useless_values out of sync, but we
   want increment it if all locs in the list that were ever referenced
   in nondebug insns are removed from the list.

   In the general case, once we do that, we'd have to stop accepting
   nondebug expressions in the loc list, to avoid having two values
   equivalent that, without debug insns, would have been made into
   separate values.  However, because debug insns never introduce
   equivalences themselves (no assignments), the only means for
   growing loc lists is through nondebug assignments.  If the locs
   also happen to be referenced in debug insns, it will work just fine.

   A consequence of this is that there's at most one debug-only loc in
   each loc list.  If we keep it in the first entry, testing whether
   we have a debug-only loc list takes O(1).

   Furthermore, since any additional entry in a loc list containing a
   debug loc would have to come from an assignment (nondebug) that
   references both the initial debug loc and the newly-equivalent loc,
   the initial debug loc would be promoted to a nondebug loc, and the
   loc list would not contain debug locs any more.

   So the only case we have to be careful with in order to keep
   n_useless_values in sync between debug and nondebug compilations is
   to avoid incrementing n_useless_values when removing the single loc
   from a value that turns out to not appear outside debug values.  We
   increment n_useless_debug_values instead, and leave such values
   alone until, for other reasons, we garbage-collect useless
   values.  */
static int n_useless_values;
static int n_useless_debug_values;

/* Count values whose locs have been taken exclusively from debug
   insns for the entire life of the value.  */
static int n_debug_values;

/* Number of useless values before we remove them from the hash table.  */
#define MAX_USELESS_VALUES 32

/* This table maps from register number to values.  It does not
   contain pointers to cselib_val structures, but rather elt_lists.
   The purpose is to be able to refer to the same register in
   different modes.  The first element of the list defines the mode in
   which the register was set; if the mode is unknown or the value is
   no longer valid in that mode, ELT will be NULL for the first
   element.  */
static struct elt_list **reg_values;
static unsigned int reg_values_size;
#define REG_VALUES(i) reg_values[i]

/* The largest number of hard regs used by any entry added to the
   REG_VALUES table.  Cleared on each cselib_clear_table() invocation.  */
static unsigned int max_value_regs;

/* Here the set of indices I with REG_VALUES(I) != 0 is saved.  This is used
   in cselib_clear_table() for fast emptying.  */
static unsigned int *used_regs;
static unsigned int n_used_regs;

/* We pass this to cselib_invalidate_mem to invalidate all of
   memory for a non-const call instruction.  */
static GTY(()) rtx callmem;

/* Set by discard_useless_locs if it deleted the last location of any
   value.  */
static int values_became_useless;

/* Used as stop element of the containing_mem list so we can check
   presence in the list by checking the next pointer.  */
static cselib_val dummy_val;

/* If non-NULL, value of the eliminated arg_pointer_rtx or frame_pointer_rtx
   that is constant through the whole function and should never be
   eliminated.  */
static cselib_val *cfa_base_preserved_val;
static unsigned int cfa_base_preserved_regno = INVALID_REGNUM;

/* Used to list all values that contain memory reference.
   May or may not contain the useless values - the list is compacted
   each time memory is invalidated.  */
static cselib_val *first_containing_mem = &dummy_val;

static object_allocator<elt_list> elt_list_pool ("elt_list");
static object_allocator<elt_loc_list> elt_loc_list_pool ("elt_loc_list");
static object_allocator<cselib_val> cselib_val_pool ("cselib_val_list");

static pool_allocator value_pool ("value", RTX_CODE_SIZE (VALUE));

/* If nonnull, cselib will call this function before freeing useless
   VALUEs.  A VALUE is deemed useless if its "locs" field is null.  */
void (*cselib_discard_hook) (cselib_val *);

/* If nonnull, cselib will call this function before recording sets or
   even clobbering outputs of INSN.  All the recorded sets will be
   represented in the array sets[n_sets].  new_val_min can be used to
   tell whether values present in sets are introduced by this
   instruction.  */
void (*cselib_record_sets_hook) (rtx_insn *insn, struct cselib_set *sets,
				 int n_sets);

#define PRESERVED_VALUE_P(RTX) \
  (RTL_FLAG_CHECK1 ("PRESERVED_VALUE_P", (RTX), VALUE)->unchanging)

#define SP_BASED_VALUE_P(RTX) \
  (RTL_FLAG_CHECK1 ("SP_BASED_VALUE_P", (RTX), VALUE)->jump)



/* Allocate a struct elt_list and fill in its two elements with the
   arguments.  */

static inline struct elt_list *
new_elt_list (struct elt_list *next, cselib_val *elt)
{
  elt_list *el = elt_list_pool.allocate ();
  el->next = next;
  el->elt = elt;
  return el;
}

/* Allocate a struct elt_loc_list with LOC and prepend it to VAL's loc
   list.  */

static inline void
new_elt_loc_list (cselib_val *val, rtx loc)
{
  struct elt_loc_list *el, *next = val->locs;

  gcc_checking_assert (!next || !next->setting_insn
		       || !DEBUG_INSN_P (next->setting_insn)
		       || cselib_current_insn == next->setting_insn);

  /* If we're creating the first loc in a debug insn context, we've
     just created a debug value.  Count it.  */
  if (!next && cselib_current_insn && DEBUG_INSN_P (cselib_current_insn))
    n_debug_values++;

  val = canonical_cselib_val (val);
  next = val->locs;

  if (GET_CODE (loc) == VALUE)
    {
      loc = canonical_cselib_val (CSELIB_VAL_PTR (loc))->val_rtx;

      gcc_checking_assert (PRESERVED_VALUE_P (loc)
			   == PRESERVED_VALUE_P (val->val_rtx));

      if (val->val_rtx == loc)
	return;
      else if (val->uid > CSELIB_VAL_PTR (loc)->uid)
	{
	  /* Reverse the insertion.  */
	  new_elt_loc_list (CSELIB_VAL_PTR (loc), val->val_rtx);
	  return;
	}

      gcc_checking_assert (val->uid < CSELIB_VAL_PTR (loc)->uid);

      if (CSELIB_VAL_PTR (loc)->locs)
	{
	  /* Bring all locs from LOC to VAL.  */
	  for (el = CSELIB_VAL_PTR (loc)->locs; el->next; el = el->next)
	    {
	      /* Adjust values that have LOC as canonical so that VAL
		 becomes their canonical.  */
	      if (el->loc && GET_CODE (el->loc) == VALUE)
		{
		  gcc_checking_assert (CSELIB_VAL_PTR (el->loc)->locs->loc
				       == loc);
		  CSELIB_VAL_PTR (el->loc)->locs->loc = val->val_rtx;
		}
	    }
	  el->next = val->locs;
	  next = val->locs = CSELIB_VAL_PTR (loc)->locs;
	}

      if (CSELIB_VAL_PTR (loc)->addr_list)
	{
	  /* Bring in addr_list into canonical node.  */
	  struct elt_list *last = CSELIB_VAL_PTR (loc)->addr_list;
	  while (last->next)
	    last = last->next;
	  last->next = val->addr_list;
	  val->addr_list = CSELIB_VAL_PTR (loc)->addr_list;
	  CSELIB_VAL_PTR (loc)->addr_list = NULL;
	}

      if (CSELIB_VAL_PTR (loc)->next_containing_mem != NULL
	  && val->next_containing_mem == NULL)
	{
	  /* Add VAL to the containing_mem list after LOC.  LOC will
	     be removed when we notice it doesn't contain any
	     MEMs.  */
	  val->next_containing_mem = CSELIB_VAL_PTR (loc)->next_containing_mem;
	  CSELIB_VAL_PTR (loc)->next_containing_mem = val;
	}

      /* Chain LOC back to VAL.  */
      el = elt_loc_list_pool.allocate ();
      el->loc = val->val_rtx;
      el->setting_insn = cselib_current_insn;
      el->next = NULL;
      CSELIB_VAL_PTR (loc)->locs = el;
    }

  el = elt_loc_list_pool.allocate ();
  el->loc = loc;
  el->setting_insn = cselib_current_insn;
  el->next = next;
  val->locs = el;
}

/* Promote loc L to a nondebug cselib_current_insn if L is marked as
   originating from a debug insn, maintaining the debug values
   count.  */

static inline void
promote_debug_loc (struct elt_loc_list *l)
{
  if (l && l->setting_insn && DEBUG_INSN_P (l->setting_insn)
      && (!cselib_current_insn || !DEBUG_INSN_P (cselib_current_insn)))
    {
      n_debug_values--;
      l->setting_insn = cselib_current_insn;
      if (cselib_preserve_constants && l->next)
	{
	  gcc_assert (l->next->setting_insn
		      && DEBUG_INSN_P (l->next->setting_insn)
		      && !l->next->next);
	  l->next->setting_insn = cselib_current_insn;
	}
      else
	gcc_assert (!l->next);
    }
}

/* The elt_list at *PL is no longer needed.  Unchain it and free its
   storage.  */

static inline void
unchain_one_elt_list (struct elt_list **pl)
{
  struct elt_list *l = *pl;

  *pl = l->next;
  elt_list_pool.remove (l);
}

/* Likewise for elt_loc_lists.  */

static void
unchain_one_elt_loc_list (struct elt_loc_list **pl)
{
  struct elt_loc_list *l = *pl;

  *pl = l->next;
  elt_loc_list_pool.remove (l);
}

/* Likewise for cselib_vals.  This also frees the addr_list associated with
   V.  */

static void
unchain_one_value (cselib_val *v)
{
  while (v->addr_list)
    unchain_one_elt_list (&v->addr_list);

  cselib_val_pool.remove (v);
}

/* Remove all entries from the hash table.  Also used during
   initialization.  */

void
cselib_clear_table (void)
{
  cselib_reset_table (1);
}

/* Return TRUE if V is a constant, a function invariant or a VALUE
   equivalence; FALSE otherwise.  */

static bool
invariant_or_equiv_p (cselib_val *v)
{
  struct elt_loc_list *l;

  if (v == cfa_base_preserved_val)
    return true;

  /* Keep VALUE equivalences around.  */
  for (l = v->locs; l; l = l->next)
    if (GET_CODE (l->loc) == VALUE)
      return true;

  if (v->locs != NULL
      && v->locs->next == NULL)
    {
      if (CONSTANT_P (v->locs->loc)
	  && (GET_CODE (v->locs->loc) != CONST
	      || !references_value_p (v->locs->loc, 0)))
	return true;
      /* Although a debug expr may be bound to different expressions,
	 we can preserve it as if it was constant, to get unification
	 and proper merging within var-tracking.  */
      if (GET_CODE (v->locs->loc) == DEBUG_EXPR
	  || GET_CODE (v->locs->loc) == DEBUG_IMPLICIT_PTR
	  || GET_CODE (v->locs->loc) == ENTRY_VALUE
	  || GET_CODE (v->locs->loc) == DEBUG_PARAMETER_REF)
	return true;

      /* (plus (value V) (const_int C)) is invariant iff V is invariant.  */
      if (GET_CODE (v->locs->loc) == PLUS
	  && CONST_INT_P (XEXP (v->locs->loc, 1))
	  && GET_CODE (XEXP (v->locs->loc, 0)) == VALUE
	  && invariant_or_equiv_p (CSELIB_VAL_PTR (XEXP (v->locs->loc, 0))))
	return true;
    }

  return false;
}

/* Remove from hash table all VALUEs except constants, function
   invariants and VALUE equivalences.  */

int
preserve_constants_and_equivs (cselib_val **x, void *info ATTRIBUTE_UNUSED)
{
  cselib_val *v = *x;

  if (invariant_or_equiv_p (v))
    {
      cselib_hasher::key lookup = {
	GET_MODE (v->val_rtx), v->val_rtx, VOIDmode
      };
      cselib_val **slot
	= cselib_preserved_hash_table->find_slot_with_hash (&lookup,
							   v->hash, INSERT);
      gcc_assert (!*slot);
      *slot = v;
    }

  cselib_hash_table->clear_slot (x);

  return 1;
}

/* Remove all entries from the hash table, arranging for the next
   value to be numbered NUM.  */

void
cselib_reset_table (unsigned int num)
{
  unsigned int i;

  max_value_regs = 0;

  if (cfa_base_preserved_val)
    {
      unsigned int regno = cfa_base_preserved_regno;
      unsigned int new_used_regs = 0;
      for (i = 0; i < n_used_regs; i++)
	if (used_regs[i] == regno)
	  {
	    new_used_regs = 1;
	    continue;
	  }
	else
	  REG_VALUES (used_regs[i]) = 0;
      gcc_assert (new_used_regs == 1);
      n_used_regs = new_used_regs;
      used_regs[0] = regno;
      max_value_regs
	= hard_regno_nregs[regno][GET_MODE (cfa_base_preserved_val->locs->loc)];
    }
  else
    {
      for (i = 0; i < n_used_regs; i++)
	REG_VALUES (used_regs[i]) = 0;
      n_used_regs = 0;
    }

  if (cselib_preserve_constants)
    cselib_hash_table->traverse <void *, preserve_constants_and_equivs>
      (NULL);
  else
    {
      cselib_hash_table->empty ();
      gcc_checking_assert (!cselib_any_perm_equivs);
    }

  n_useless_values = 0;
  n_useless_debug_values = 0;
  n_debug_values = 0;

  next_uid = num;

  first_containing_mem = &dummy_val;
}

/* Return the number of the next value that will be generated.  */

unsigned int
cselib_get_next_uid (void)
{
  return next_uid;
}

/* Search for X, whose hashcode is HASH, in CSELIB_HASH_TABLE,
   INSERTing if requested.  When X is part of the address of a MEM,
   MEMMODE should specify the mode of the MEM.  */

static cselib_val **
cselib_find_slot (machine_mode mode, rtx x, hashval_t hash,
		  enum insert_option insert, machine_mode memmode)
{
  cselib_val **slot = NULL;
  cselib_hasher::key lookup = { mode, x, memmode };
  if (cselib_preserve_constants)
    slot = cselib_preserved_hash_table->find_slot_with_hash (&lookup, hash,
							     NO_INSERT);
  if (!slot)
    slot = cselib_hash_table->find_slot_with_hash (&lookup, hash, insert);
  return slot;
}

/* Return true if X contains a VALUE rtx.  If ONLY_USELESS is set, we
   only return true for values which point to a cselib_val whose value
   element has been set to zero, which implies the cselib_val will be
   removed.  */

int
references_value_p (const_rtx x, int only_useless)
{
  const enum rtx_code code = GET_CODE (x);
  const char *fmt = GET_RTX_FORMAT (code);
  int i, j;

  if (GET_CODE (x) == VALUE
      && (! only_useless ||
	  (CSELIB_VAL_PTR (x)->locs == 0 && !PRESERVED_VALUE_P (x))))
    return 1;

  for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
    {
      if (fmt[i] == 'e' && references_value_p (XEXP (x, i), only_useless))
	return 1;
      else if (fmt[i] == 'E')
	for (j = 0; j < XVECLEN (x, i); j++)
	  if (references_value_p (XVECEXP (x, i, j), only_useless))
	    return 1;
    }

  return 0;
}

/* For all locations found in X, delete locations that reference useless
   values (i.e. values without any location).  Called through
   htab_traverse.  */

int
discard_useless_locs (cselib_val **x, void *info ATTRIBUTE_UNUSED)
{
  cselib_val *v = *x;
  struct elt_loc_list **p = &v->locs;
  bool had_locs = v->locs != NULL;
  rtx_insn *setting_insn = v->locs ? v->locs->setting_insn : NULL;

  while (*p)
    {
      if (references_value_p ((*p)->loc, 1))
	unchain_one_elt_loc_list (p);
      else
	p = &(*p)->next;
    }

  if (had_locs && v->locs == 0 && !PRESERVED_VALUE_P (v->val_rtx))
    {
      if (setting_insn && DEBUG_INSN_P (setting_insn))
	n_useless_debug_values++;
      else
	n_useless_values++;
      values_became_useless = 1;
    }
  return 1;
}

/* If X is a value with no locations, remove it from the hashtable.  */

int
discard_useless_values (cselib_val **x, void *info ATTRIBUTE_UNUSED)
{
  cselib_val *v = *x;

  if (v->locs == 0 && !PRESERVED_VALUE_P (v->val_rtx))
    {
      if (cselib_discard_hook)
	cselib_discard_hook (v);

      CSELIB_VAL_PTR (v->val_rtx) = NULL;
      cselib_hash_table->clear_slot (x);
      unchain_one_value (v);
      n_useless_values--;
    }

  return 1;
}

/* Clean out useless values (i.e. those which no longer have locations
   associated with them) from the hash table.  */

static void
remove_useless_values (void)
{
  cselib_val **p, *v;

  /* First pass: eliminate locations that reference the value.  That in
     turn can make more values useless.  */
  do
    {
      values_became_useless = 0;
      cselib_hash_table->traverse <void *, discard_useless_locs> (NULL);
    }
  while (values_became_useless);

  /* Second pass: actually remove the values.  */

  p = &first_containing_mem;
  for (v = *p; v != &dummy_val; v = v->next_containing_mem)
    if (v->locs && v == canonical_cselib_val (v))
      {
	*p = v;
	p = &(*p)->next_containing_mem;
      }
  *p = &dummy_val;

  n_useless_values += n_useless_debug_values;
  n_debug_values -= n_useless_debug_values;
  n_useless_debug_values = 0;

  cselib_hash_table->traverse <void *, discard_useless_values> (NULL);

  gcc_assert (!n_useless_values);
}

/* Arrange for a value to not be removed from the hash table even if
   it becomes useless.  */

void
cselib_preserve_value (cselib_val *v)
{
  PRESERVED_VALUE_P (v->val_rtx) = 1;
}

/* Test whether a value is preserved.  */

bool
cselib_preserved_value_p (cselib_val *v)
{
  return PRESERVED_VALUE_P (v->val_rtx);
}

/* Arrange for a REG value to be assumed constant through the whole function,
   never invalidated and preserved across cselib_reset_table calls.  */

void
cselib_preserve_cfa_base_value (cselib_val *v, unsigned int regno)
{
  if (cselib_preserve_constants
      && v->locs
      && REG_P (v->locs->loc))
    {
      cfa_base_preserved_val = v;
      cfa_base_preserved_regno = regno;
    }
}

/* Clean all non-constant expressions in the hash table, but retain
   their values.  */

void
cselib_preserve_only_values (void)
{
  int i;

  for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
    cselib_invalidate_regno (i, reg_raw_mode[i]);

  cselib_invalidate_mem (callmem);

  remove_useless_values ();

  gcc_assert (first_containing_mem == &dummy_val);
}

/* Arrange for a value to be marked as based on stack pointer
   for find_base_term purposes.  */

void
cselib_set_value_sp_based (cselib_val *v)
{
  SP_BASED_VALUE_P (v->val_rtx) = 1;
}

/* Test whether a value is based on stack pointer for
   find_base_term purposes.  */

bool
cselib_sp_based_value_p (cselib_val *v)
{
  return SP_BASED_VALUE_P (v->val_rtx);
}

/* Return the mode in which a register was last set.  If X is not a
   register, return its mode.  If the mode in which the register was
   set is not known, or the value was already clobbered, return
   VOIDmode.  */

machine_mode
cselib_reg_set_mode (const_rtx x)
{
  if (!REG_P (x))
    return GET_MODE (x);

  if (REG_VALUES (REGNO (x)) == NULL
      || REG_VALUES (REGNO (x))->elt == NULL)
    return VOIDmode;

  return GET_MODE (REG_VALUES (REGNO (x))->elt->val_rtx);
}

/* If x is a PLUS or an autoinc operation, expand the operation,
   storing the offset, if any, in *OFF.  */

static rtx
autoinc_split (rtx x, rtx *off, machine_mode memmode)
{
  switch (GET_CODE (x))
    {
    case PLUS:
      *off = XEXP (x, 1);
      return XEXP (x, 0);

    case PRE_DEC:
      if (memmode == VOIDmode)
	return x;

      *off = GEN_INT (-GET_MODE_SIZE (memmode));
      return XEXP (x, 0);

    case PRE_INC:
      if (memmode == VOIDmode)
	return x;

      *off = GEN_INT (GET_MODE_SIZE (memmode));
      return XEXP (x, 0);

    case PRE_MODIFY:
      return XEXP (x, 1);

    case POST_DEC:
    case POST_INC:
    case POST_MODIFY:
      return XEXP (x, 0);

    default:
      return x;
    }
}

/* Return nonzero if we can prove that X and Y contain the same value,
   taking our gathered information into account.  MEMMODE holds the
   mode of the enclosing MEM, if any, as required to deal with autoinc
   addressing modes.  If X and Y are not (known to be) part of
   addresses, MEMMODE should be VOIDmode.  */

int
rtx_equal_for_cselib_1 (rtx x, rtx y, machine_mode memmode)
{
  enum rtx_code code;
  const char *fmt;
  int i;

  if (REG_P (x) || MEM_P (x))
    {
      cselib_val *e = cselib_lookup (x, GET_MODE (x), 0, memmode);

      if (e)
	x = e->val_rtx;
    }

  if (REG_P (y) || MEM_P (y))
    {
      cselib_val *e = cselib_lookup (y, GET_MODE (y), 0, memmode);

      if (e)
	y = e->val_rtx;
    }

  if (x == y)
    return 1;

  if (GET_CODE (x) == VALUE)
    {
      cselib_val *e = canonical_cselib_val (CSELIB_VAL_PTR (x));
      struct elt_loc_list *l;

      if (GET_CODE (y) == VALUE)
	return e == canonical_cselib_val (CSELIB_VAL_PTR (y));

      for (l = e->locs; l; l = l->next)
	{
	  rtx t = l->loc;

	  /* Avoid infinite recursion.  We know we have the canonical
	     value, so we can just skip any values in the equivalence
	     list.  */
	  if (REG_P (t) || MEM_P (t) || GET_CODE (t) == VALUE)
	    continue;
	  else if (rtx_equal_for_cselib_1 (t, y, memmode))
	    return 1;
	}

      return 0;
    }
  else if (GET_CODE (y) == VALUE)
    {
      cselib_val *e = canonical_cselib_val (CSELIB_VAL_PTR (y));
      struct elt_loc_list *l;

      for (l = e->locs; l; l = l->next)
	{
	  rtx t = l->loc;

	  if (REG_P (t) || MEM_P (t) || GET_CODE (t) == VALUE)
	    continue;
	  else if (rtx_equal_for_cselib_1 (x, t, memmode))
	    return 1;
	}

      return 0;
    }

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

  if (GET_CODE (x) != GET_CODE (y))
    {
      rtx xorig = x, yorig = y;
      rtx xoff = NULL, yoff = NULL;

      x = autoinc_split (x, &xoff, memmode);
      y = autoinc_split (y, &yoff, memmode);

      if (!xoff != !yoff)
	return 0;

      if (xoff && !rtx_equal_for_cselib_1 (xoff, yoff, memmode))
	return 0;

      /* Don't recurse if nothing changed.  */
      if (x != xorig || y != yorig)
	return rtx_equal_for_cselib_1 (x, y, memmode);

      return 0;
    }

  /* These won't be handled correctly by the code below.  */
  switch (GET_CODE (x))
    {
    CASE_CONST_UNIQUE:
    case DEBUG_EXPR:
      return 0;

    case DEBUG_IMPLICIT_PTR:
      return DEBUG_IMPLICIT_PTR_DECL (x)
	     == DEBUG_IMPLICIT_PTR_DECL (y);

    case DEBUG_PARAMETER_REF:
      return DEBUG_PARAMETER_REF_DECL (x)
	     == DEBUG_PARAMETER_REF_DECL (y);

    case ENTRY_VALUE:
      /* ENTRY_VALUEs are function invariant, it is thus undesirable to
	 use rtx_equal_for_cselib_1 to compare the operands.  */
      return rtx_equal_p (ENTRY_VALUE_EXP (x), ENTRY_VALUE_EXP (y));

    case LABEL_REF:
      return label_ref_label (x) == label_ref_label (y);

    case REG:
      return REGNO (x) == REGNO (y);

    case MEM:
      /* We have to compare any autoinc operations in the addresses
	 using this MEM's mode.  */
      return rtx_equal_for_cselib_1 (XEXP (x, 0), XEXP (y, 0), GET_MODE (x));

    default:
      break;
    }

  code = GET_CODE (x);
  fmt = GET_RTX_FORMAT (code);

  for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
    {
      int j;

      switch (fmt[i])
	{
	case 'w':
	  if (XWINT (x, i) != XWINT (y, i))
	    return 0;
	  break;

	case 'n':
	case 'i':
	  if (XINT (x, i) != XINT (y, i))
	    return 0;
	  break;

	case 'V':
	case 'E':
	  /* Two vectors must have the same length.  */
	  if (XVECLEN (x, i) != XVECLEN (y, i))
	    return 0;

	  /* And the corresponding elements must match.  */
	  for (j = 0; j < XVECLEN (x, i); j++)
	    if (! rtx_equal_for_cselib_1 (XVECEXP (x, i, j),
					  XVECEXP (y, i, j), memmode))
	      return 0;
	  break;

	case 'e':
	  if (i == 1
	      && targetm.commutative_p (x, UNKNOWN)
	      && rtx_equal_for_cselib_1 (XEXP (x, 1), XEXP (y, 0), memmode)
	      && rtx_equal_for_cselib_1 (XEXP (x, 0), XEXP (y, 1), memmode))
	    return 1;
	  if (! rtx_equal_for_cselib_1 (XEXP (x, i), XEXP (y, i), memmode))
	    return 0;
	  break;

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

	case 'u':
	  /* These are just backpointers, so they don't matter.  */
	  break;

	case '0':
	case 't':
	  break;

	  /* It is believed that rtx's at this level will never
	     contain anything but integers and other rtx's,
	     except for within LABEL_REFs and SYMBOL_REFs.  */
	default:
	  gcc_unreachable ();
	}
    }
  return 1;
}

/* Hash an rtx.  Return 0 if we couldn't hash the rtx.
   For registers and memory locations, we look up their cselib_val structure
   and return its VALUE element.
   Possible reasons for return 0 are: the object is volatile, or we couldn't
   find a register or memory location in the table and CREATE is zero.  If
   CREATE is nonzero, table elts are created for regs and mem.
   N.B. this hash function returns the same hash value for RTXes that
   differ only in the order of operands, thus it is suitable for comparisons
   that take commutativity into account.
   If we wanted to also support associative rules, we'd have to use a different
   strategy to avoid returning spurious 0, e.g. return ~(~0U >> 1) .
   MEMMODE indicates the mode of an enclosing MEM, and it's only
   used to compute autoinc values.
   We used to have a MODE argument for hashing for CONST_INTs, but that
   didn't make sense, since it caused spurious hash differences between
    (set (reg:SI 1) (const_int))
    (plus:SI (reg:SI 2) (reg:SI 1))
   and
    (plus:SI (reg:SI 2) (const_int))
   If the mode is important in any context, it must be checked specifically
   in a comparison anyway, since relying on hash differences is unsafe.  */

static unsigned int
cselib_hash_rtx (rtx x, int create, machine_mode memmode)
{
  cselib_val *e;
  int i, j;
  enum rtx_code code;
  const char *fmt;
  unsigned int hash = 0;

  code = GET_CODE (x);
  hash += (unsigned) code + (unsigned) GET_MODE (x);

  switch (code)
    {
    case VALUE:
      e = CSELIB_VAL_PTR (x);
      return e->hash;

    case MEM:
    case REG:
      e = cselib_lookup (x, GET_MODE (x), create, memmode);
      if (! e)
	return 0;

      return e->hash;

    case DEBUG_EXPR:
      hash += ((unsigned) DEBUG_EXPR << 7)
	      + DEBUG_TEMP_UID (DEBUG_EXPR_TREE_DECL (x));
      return hash ? hash : (unsigned int) DEBUG_EXPR;

    case DEBUG_IMPLICIT_PTR:
      hash += ((unsigned) DEBUG_IMPLICIT_PTR << 7)
	      + DECL_UID (DEBUG_IMPLICIT_PTR_DECL (x));
      return hash ? hash : (unsigned int) DEBUG_IMPLICIT_PTR;

    case DEBUG_PARAMETER_REF:
      hash += ((unsigned) DEBUG_PARAMETER_REF << 7)
	      + DECL_UID (DEBUG_PARAMETER_REF_DECL (x));
      return hash ? hash : (unsigned int) DEBUG_PARAMETER_REF;

    case ENTRY_VALUE:
      /* ENTRY_VALUEs are function invariant, thus try to avoid
	 recursing on argument if ENTRY_VALUE is one of the
	 forms emitted by expand_debug_expr, otherwise
	 ENTRY_VALUE hash would depend on the current value
	 in some register or memory.  */
      if (REG_P (ENTRY_VALUE_EXP (x)))
	hash += (unsigned int) REG
		+ (unsigned int) GET_MODE (ENTRY_VALUE_EXP (x))
		+ (unsigned int) REGNO (ENTRY_VALUE_EXP (x));
      else if (MEM_P (ENTRY_VALUE_EXP (x))
	       && REG_P (XEXP (ENTRY_VALUE_EXP (x), 0)))
	hash += (unsigned int) MEM
		+ (unsigned int) GET_MODE (XEXP (ENTRY_VALUE_EXP (x), 0))
		+ (unsigned int) REGNO (XEXP (ENTRY_VALUE_EXP (x), 0));
      else
	hash += cselib_hash_rtx (ENTRY_VALUE_EXP (x), create, memmode);
      return hash ? hash : (unsigned int) ENTRY_VALUE;

    case CONST_INT:
      hash += ((unsigned) CONST_INT << 7) + UINTVAL (x);
      return hash ? hash : (unsigned int) CONST_INT;

    case CONST_WIDE_INT:
      for (i = 0; i < CONST_WIDE_INT_NUNITS (x); i++)
	hash += CONST_WIDE_INT_ELT (x, i);
      return hash;

    case CONST_DOUBLE:
      /* This is like the general case, except that it only counts
	 the integers representing the constant.  */
      hash += (unsigned) code + (unsigned) GET_MODE (x);
      if (TARGET_SUPPORTS_WIDE_INT == 0 && GET_MODE (x) == VOIDmode)
	hash += ((unsigned) CONST_DOUBLE_LOW (x)
		 + (unsigned) CONST_DOUBLE_HIGH (x));
      else
	hash += real_hash (CONST_DOUBLE_REAL_VALUE (x));
      return hash ? hash : (unsigned int) CONST_DOUBLE;

    case CONST_FIXED:
      hash += (unsigned int) code + (unsigned int) GET_MODE (x);
      hash += fixed_hash (CONST_FIXED_VALUE (x));
      return hash ? hash : (unsigned int) CONST_FIXED;

    case CONST_VECTOR:
      {
	int units;
	rtx elt;

	units = CONST_VECTOR_NUNITS (x);

	for (i = 0; i < units; ++i)
	  {
	    elt = CONST_VECTOR_ELT (x, i);
	    hash += cselib_hash_rtx (elt, 0, memmode);
	  }

	return hash;
      }

      /* Assume there is only one rtx object for any given label.  */
    case LABEL_REF:
      /* We don't hash on the address of the CODE_LABEL to avoid bootstrap
	 differences and differences between each stage's debugging dumps.  */
      hash += (((unsigned int) LABEL_REF << 7)
	       + CODE_LABEL_NUMBER (label_ref_label (x)));
      return hash ? hash : (unsigned int) LABEL_REF;

    case SYMBOL_REF:
      {
	/* Don't hash on the symbol's address to avoid bootstrap differences.
	   Different hash values may cause expressions to be recorded in
	   different orders and thus different registers to be used in the
	   final assembler.  This also avoids differences in the dump files
	   between various stages.  */
	unsigned int h = 0;
	const unsigned char *p = (const unsigned char *) XSTR (x, 0);

	while (*p)
	  h += (h << 7) + *p++; /* ??? revisit */

	hash += ((unsigned int) SYMBOL_REF << 7) + h;
	return hash ? hash : (unsigned int) SYMBOL_REF;
      }

    case PRE_DEC:
    case PRE_INC:
      /* We can't compute these without knowing the MEM mode.  */
      gcc_assert (memmode != VOIDmode);
      i = GET_MODE_SIZE (memmode);
      if (code == PRE_DEC)
	i = -i;
      /* Adjust the hash so that (mem:MEMMODE (pre_* (reg))) hashes
	 like (mem:MEMMODE (plus (reg) (const_int I))).  */
      hash += (unsigned) PLUS - (unsigned)code
	+ cselib_hash_rtx (XEXP (x, 0), create, memmode)
	+ cselib_hash_rtx (GEN_INT (i), create, memmode);
      return hash ? hash : 1 + (unsigned) PLUS;

    case PRE_MODIFY:
      gcc_assert (memmode != VOIDmode);
      return cselib_hash_rtx (XEXP (x, 1), create, memmode);

    case POST_DEC:
    case POST_INC:
    case POST_MODIFY:
      gcc_assert (memmode != VOIDmode);
      return cselib_hash_rtx (XEXP (x, 0), create, memmode);

    case PC:
    case CC0:
    case CALL:
    case UNSPEC_VOLATILE:
      return 0;

    case ASM_OPERANDS:
      if (MEM_VOLATILE_P (x))
	return 0;

      break;

    default:
      break;
    }

  i = GET_RTX_LENGTH (code) - 1;
  fmt = GET_RTX_FORMAT (code);
  for (; i >= 0; i--)
    {
      switch (fmt[i])
	{
	case 'e':
	  {
	    rtx tem = XEXP (x, i);
	    unsigned int tem_hash = cselib_hash_rtx (tem, create, memmode);

	    if (tem_hash == 0)
	      return 0;

	    hash += tem_hash;
	  }
	  break;
	case 'E':
	  for (j = 0; j < XVECLEN (x, i); j++)
	    {
	      unsigned int tem_hash
		= cselib_hash_rtx (XVECEXP (x, i, j), create, memmode);

	      if (tem_hash == 0)
		return 0;

	      hash += tem_hash;
	    }
	  break;

	case 's':
	  {
	    const unsigned char *p = (const unsigned char *) XSTR (x, i);

	    if (p)
	      while (*p)
		hash += *p++;
	    break;
	  }

	case 'i':
	  hash += XINT (x, i);
	  break;

	case '0':
	case 't':
	  /* unused */
	  break;

	default:
	  gcc_unreachable ();
	}
    }

  return hash ? hash : 1 + (unsigned int) GET_CODE (x);
}

/* Create a new value structure for VALUE and initialize it.  The mode of the
   value is MODE.  */

static inline cselib_val *
new_cselib_val (unsigned int hash, machine_mode mode, rtx x)
{
  cselib_val *e = cselib_val_pool.allocate ();

  gcc_assert (hash);
  gcc_assert (next_uid);

  e->hash = hash;
  e->uid = next_uid++;
  /* We use an alloc pool to allocate this RTL construct because it
     accounts for about 8% of the overall memory usage.  We know
     precisely when we can have VALUE RTXen (when cselib is active)
     so we don't need to put them in garbage collected memory.
     ??? Why should a VALUE be an RTX in the first place?  */
  e->val_rtx = (rtx_def*) value_pool.allocate ();
  memset (e->val_rtx, 0, RTX_HDR_SIZE);
  PUT_CODE (e->val_rtx, VALUE);
  PUT_MODE (e->val_rtx, mode);
  CSELIB_VAL_PTR (e->val_rtx) = e;
  e->addr_list = 0;
  e->locs = 0;
  e->next_containing_mem = 0;

  if (dump_file && (dump_flags & TDF_CSELIB))
    {
      fprintf (dump_file, "cselib value %u:%u ", e->uid, hash);
      if (flag_dump_noaddr || flag_dump_unnumbered)
	fputs ("# ", dump_file);
      else
	fprintf (dump_file, "%p ", (void*)e);
      print_rtl_single (dump_file, x);
      fputc ('\n', dump_file);
    }

  return e;
}

/* ADDR_ELT is a value that is used as address.  MEM_ELT is the value that
   contains the data at this address.  X is a MEM that represents the
   value.  Update the two value structures to represent this situation.  */

static void
add_mem_for_addr (cselib_val *addr_elt, cselib_val *mem_elt, rtx x)
{
  addr_elt = canonical_cselib_val (addr_elt);
  mem_elt = canonical_cselib_val (mem_elt);

  /* Avoid duplicates.  */
  addr_space_t as = MEM_ADDR_SPACE (x);
  for (elt_loc_list *l = mem_elt->locs; l; l = l->next)
    if (MEM_P (l->loc)
	&& CSELIB_VAL_PTR (XEXP (l->loc, 0)) == addr_elt
        && MEM_ADDR_SPACE (l->loc) == as)
      {
	promote_debug_loc (l);
	return;
      }

  addr_elt->addr_list = new_elt_list (addr_elt->addr_list, mem_elt);
  new_elt_loc_list (mem_elt,
		    replace_equiv_address_nv (x, addr_elt->val_rtx));
  if (mem_elt->next_containing_mem == NULL)
    {
      mem_elt->next_containing_mem = first_containing_mem;
      first_containing_mem = mem_elt;
    }
}

/* Subroutine of cselib_lookup.  Return a value for X, which is a MEM rtx.
   If CREATE, make a new one if we haven't seen it before.  */

static cselib_val *
cselib_lookup_mem (rtx x, int create)
{
  machine_mode mode = GET_MODE (x);
  machine_mode addr_mode;
  cselib_val **slot;
  cselib_val *addr;
  cselib_val *mem_elt;

  if (MEM_VOLATILE_P (x) || mode == BLKmode
      || !cselib_record_memory
      || (FLOAT_MODE_P (mode) && flag_float_store))
    return 0;

  addr_mode = GET_MODE (XEXP (x, 0));
  if (addr_mode == VOIDmode)
    addr_mode = Pmode;

  /* Look up the value for the address.  */
  addr = cselib_lookup (XEXP (x, 0), addr_mode, create, mode);
  if (! addr)
    return 0;
  addr = canonical_cselib_val (addr);

  /* Find a value that describes a value of our mode at that address.  */
  addr_space_t as = MEM_ADDR_SPACE (x);
  for (elt_list *l = addr->addr_list; l; l = l->next)
    if (GET_MODE (l->elt->val_rtx) == mode)
      {
	for (elt_loc_list *l2 = l->elt->locs; l2; l2 = l2->next)
	  if (MEM_P (l2->loc) && MEM_ADDR_SPACE (l2->loc) == as)
	    {
	      promote_debug_loc (l->elt->locs);
	      return l->elt;
	    }
      }

  if (! create)
    return 0;

  mem_elt = new_cselib_val (next_uid, mode, x);
  add_mem_for_addr (addr, mem_elt, x);
  slot = cselib_find_slot (mode, x, mem_elt->hash, INSERT, VOIDmode);
  *slot = mem_elt;
  return mem_elt;
}

/* Search through the possible substitutions in P.  We prefer a non reg
   substitution because this allows us to expand the tree further.  If
   we find, just a reg, take the lowest regno.  There may be several
   non-reg results, we just take the first one because they will all
   expand to the same place.  */

static rtx
expand_loc (struct elt_loc_list *p, struct expand_value_data *evd,
	    int max_depth)
{
  rtx reg_result = NULL;
  unsigned int regno = UINT_MAX;
  struct elt_loc_list *p_in = p;

  for (; p; p = p->next)
    {
      /* Return these right away to avoid returning stack pointer based
	 expressions for frame pointer and vice versa, which is something
	 that would confuse DSE.  See the comment in cselib_expand_value_rtx_1
	 for more details.  */
      if (REG_P (p->loc)
	  && (REGNO (p->loc) == STACK_POINTER_REGNUM
	      || REGNO (p->loc) == FRAME_POINTER_REGNUM
	      || REGNO (p->loc) == HARD_FRAME_POINTER_REGNUM
	      || REGNO (p->loc) == cfa_base_preserved_regno))
	return p->loc;
      /* Avoid infinite recursion trying to expand a reg into a
	 the same reg.  */
      if ((REG_P (p->loc))
	  && (REGNO (p->loc) < regno)
	  && !bitmap_bit_p (evd->regs_active, REGNO (p->loc)))
	{
	  reg_result = p->loc;
	  regno = REGNO (p->loc);
	}
      /* Avoid infinite recursion and do not try to expand the
	 value.  */
      else if (GET_CODE (p->loc) == VALUE
	       && CSELIB_VAL_PTR (p->loc)->locs == p_in)
	continue;
      else if (!REG_P (p->loc))
	{
	  rtx result, note;
	  if (dump_file && (dump_flags & TDF_CSELIB))
	    {
	      print_inline_rtx (dump_file, p->loc, 0);
	      fprintf (dump_file, "\n");
	    }
	  if (GET_CODE (p->loc) == LO_SUM
	      && GET_CODE (XEXP (p->loc, 1)) == SYMBOL_REF
	      && p->setting_insn
	      && (note = find_reg_note (p->setting_insn, REG_EQUAL, NULL_RTX))
	      && XEXP (note, 0) == XEXP (p->loc, 1))
	    return XEXP (p->loc, 1);
	  result = cselib_expand_value_rtx_1 (p->loc, evd, max_depth - 1);
	  if (result)
	    return result;
	}

    }

  if (regno != UINT_MAX)
    {
      rtx result;
      if (dump_file && (dump_flags & TDF_CSELIB))
	fprintf (dump_file, "r%d\n", regno);

      result = cselib_expand_value_rtx_1 (reg_result, evd, max_depth - 1);
      if (result)
	return result;
    }

  if (dump_file && (dump_flags & TDF_CSELIB))
    {
      if (reg_result)
	{
	  print_inline_rtx (dump_file, reg_result, 0);
	  fprintf (dump_file, "\n");
	}
      else
	fprintf (dump_file, "NULL\n");
    }
  return reg_result;
}


/* Forward substitute and expand an expression out to its roots.
   This is the opposite of common subexpression.  Because local value
   numbering is such a weak optimization, the expanded expression is
   pretty much unique (not from a pointer equals point of view but
   from a tree shape point of view.

   This function returns NULL if the expansion fails.  The expansion
   will fail if there is no value number for one of the operands or if
   one of the operands has been overwritten between the current insn
   and the beginning of the basic block.  For instance x has no
   expansion in:

   r1 <- r1 + 3
   x <- r1 + 8

   REGS_ACTIVE is a scratch bitmap that should be clear when passing in.
   It is clear on return.  */

rtx
cselib_expand_value_rtx (rtx orig, bitmap regs_active, int max_depth)
{
  struct expand_value_data evd;

  evd.regs_active = regs_active;
  evd.callback = NULL;
  evd.callback_arg = NULL;
  evd.dummy = false;

  return cselib_expand_value_rtx_1 (orig, &evd, max_depth);
}

/* Same as cselib_expand_value_rtx, but using a callback to try to
   resolve some expressions.  The CB function should return ORIG if it
   can't or does not want to deal with a certain RTX.  Any other
   return value, including NULL, will be used as the expansion for
   VALUE, without any further changes.  */

rtx
cselib_expand_value_rtx_cb (rtx orig, bitmap regs_active, int max_depth,
			    cselib_expand_callback cb, void *data)
{
  struct expand_value_data evd;

  evd.regs_active = regs_active;
  evd.callback = cb;
  evd.callback_arg = data;
  evd.dummy = false;

  return cselib_expand_value_rtx_1 (orig, &evd, max_depth);
}

/* Similar to cselib_expand_value_rtx_cb, but no rtxs are actually copied
   or simplified.  Useful to find out whether cselib_expand_value_rtx_cb
   would return NULL or non-NULL, without allocating new rtx.  */

bool
cselib_dummy_expand_value_rtx_cb (rtx orig, bitmap regs_active, int max_depth,
				  cselib_expand_callback cb, void *data)
{
  struct expand_value_data evd;

  evd.regs_active = regs_active;
  evd.callback = cb;
  evd.callback_arg = data;
  evd.dummy = true;

  return cselib_expand_value_rtx_1 (orig, &evd, max_depth) != NULL;
}

/* Internal implementation of cselib_expand_value_rtx and
   cselib_expand_value_rtx_cb.  */

static rtx
cselib_expand_value_rtx_1 (rtx orig, struct expand_value_data *evd,
			   int max_depth)
{
  rtx copy, scopy;
  int i, j;
  RTX_CODE code;
  const char *format_ptr;
  machine_mode mode;

  code = GET_CODE (orig);

  /* For the context of dse, if we end up expand into a huge tree, we
     will not have a useful address, so we might as well just give up
     quickly.  */
  if (max_depth <= 0)
    return NULL;

  switch (code)
    {
    case REG:
      {
	struct elt_list *l = REG_VALUES (REGNO (orig));

	if (l && l->elt == NULL)
	  l = l->next;
	for (; l; l = l->next)
	  if (GET_MODE (l->elt->val_rtx) == GET_MODE (orig))
	    {
	      rtx result;
	      unsigned regno = REGNO (orig);

	      /* The only thing that we are not willing to do (this
		 is requirement of dse and if others potential uses
		 need this function we should add a parm to control
		 it) is that we will not substitute the
		 STACK_POINTER_REGNUM, FRAME_POINTER or the
		 HARD_FRAME_POINTER.

		 These expansions confuses the code that notices that
		 stores into the frame go dead at the end of the
		 function and that the frame is not effected by calls
		 to subroutines.  If you allow the
		 STACK_POINTER_REGNUM substitution, then dse will
		 think that parameter pushing also goes dead which is
		 wrong.  If you allow the FRAME_POINTER or the
		 HARD_FRAME_POINTER then you lose the opportunity to
		 make the frame assumptions.  */
	      if (regno == STACK_POINTER_REGNUM
		  || regno == FRAME_POINTER_REGNUM
		  || regno == HARD_FRAME_POINTER_REGNUM
		  || regno == cfa_base_preserved_regno)
		return orig;

	      bitmap_set_bit (evd->regs_active, regno);

	      if (dump_file && (dump_flags & TDF_CSELIB))
		fprintf (dump_file, "expanding: r%d into: ", regno);

	      result = expand_loc (l->elt->locs, evd, max_depth);
	      bitmap_clear_bit (evd->regs_active, regno);

	      if (result)
		return result;
	      else
		return orig;
	    }
	return orig;
      }

    CASE_CONST_ANY:
    case SYMBOL_REF:
    case CODE_LABEL:
    case PC:
    case CC0:
    case SCRATCH:
      /* SCRATCH must be shared because they represent distinct values.  */
      return orig;
    case CLOBBER:
      if (REG_P (XEXP (orig, 0)) && HARD_REGISTER_NUM_P (REGNO (XEXP (orig, 0))))
	return orig;
      break;

    case CONST:
      if (shared_const_p (orig))
	return orig;
      break;

    case SUBREG:
      {
	rtx subreg;

	if (evd->callback)
	  {
	    subreg = evd->callback (orig, evd->regs_active, max_depth,
				    evd->callback_arg);
	    if (subreg != orig)
	      return subreg;
	  }

	subreg = cselib_expand_value_rtx_1 (SUBREG_REG (orig), evd,
					    max_depth - 1);
	if (!subreg)
	  return NULL;
	scopy = simplify_gen_subreg (GET_MODE (orig), subreg,
				     GET_MODE (SUBREG_REG (orig)),
				     SUBREG_BYTE (orig));
	if (scopy == NULL
	    || (GET_CODE (scopy) == SUBREG
		&& !REG_P (SUBREG_REG (scopy))
		&& !MEM_P (SUBREG_REG (scopy))))
	  return NULL;

	return scopy;
      }

    case VALUE:
      {
	rtx result;

	if (dump_file && (dump_flags & TDF_CSELIB))
	  {
	    fputs ("\nexpanding ", dump_file);
	    print_rtl_single (dump_file, orig);
	    fputs (" into...", dump_file);
	  }

	if (evd->callback)
	  {
	    result = evd->callback (orig, evd->regs_active, max_depth,
				    evd->callback_arg);

	    if (result != orig)
	      return result;
	  }

	result = expand_loc (CSELIB_VAL_PTR (orig)->locs, evd, max_depth);
	return result;
      }

    case DEBUG_EXPR:
      if (evd->callback)
	return evd->callback (orig, evd->regs_active, max_depth,
			      evd->callback_arg);
      return orig;

    default:
      break;
    }

  /* Copy the various flags, fields, and other information.  We assume
     that all fields need copying, and then clear the fields that should
     not be copied.  That is the sensible default behavior, and forces
     us to explicitly document why we are *not* copying a flag.  */
  if (evd->dummy)
    copy = NULL;
  else
    copy = shallow_copy_rtx (orig);

  format_ptr = GET_RTX_FORMAT (code);

  for (i = 0; i < GET_RTX_LENGTH (code); i++)
    switch (*format_ptr++)
      {
      case 'e':
	if (XEXP (orig, i) != NULL)
	  {
	    rtx result = cselib_expand_value_rtx_1 (XEXP (orig, i), evd,
						    max_depth - 1);
	    if (!result)
	      return NULL;
	    if (copy)
	      XEXP (copy, i) = result;
	  }
	break;

      case 'E':
      case 'V':
	if (XVEC (orig, i) != NULL)
	  {
	    if (copy)
	      XVEC (copy, i) = rtvec_alloc (XVECLEN (orig, i));
	    for (j = 0; j < XVECLEN (orig, i); j++)
	      {
		rtx result = cselib_expand_value_rtx_1 (XVECEXP (orig, i, j),
							evd, max_depth - 1);
		if (!result)
		  return NULL;
		if (copy)
		  XVECEXP (copy, i, j) = result;
	      }
	  }
	break;

      case 't':
      case 'w':
      case 'i':
      case 's':
      case 'S':
      case 'T':
      case 'u':
      case 'B':
      case '0':
	/* These are left unchanged.  */
	break;

      default:
	gcc_unreachable ();
      }

  if (evd->dummy)
    return orig;

  mode = GET_MODE (copy);
  /* If an operand has been simplified into CONST_INT, which doesn't
     have a mode and the mode isn't derivable from whole rtx's mode,
     try simplify_*_operation first with mode from original's operand
     and as a fallback wrap CONST_INT into gen_rtx_CONST.  */
  scopy = copy;
  switch (GET_RTX_CLASS (code))
    {
    case RTX_UNARY:
      if (CONST_INT_P (XEXP (copy, 0))
	  && GET_MODE (XEXP (orig, 0)) != VOIDmode)
	{
	  scopy = simplify_unary_operation (code, mode, XEXP (copy, 0),
					    GET_MODE (XEXP (orig, 0)));
	  if (scopy)
	    return scopy;
	}
      break;
    case RTX_COMM_ARITH:
    case RTX_BIN_ARITH:
      /* These expressions can derive operand modes from the whole rtx's mode.  */
      break;
    case RTX_TERNARY:
    case RTX_BITFIELD_OPS:
      if (CONST_INT_P (XEXP (copy, 0))
	  && GET_MODE (XEXP (orig, 0)) != VOIDmode)
	{
	  scopy = simplify_ternary_operation (code, mode,
					      GET_MODE (XEXP (orig, 0)),
					      XEXP (copy, 0), XEXP (copy, 1),
					      XEXP (copy, 2));
	  if (scopy)
	    return scopy;
	}
      break;
    case RTX_COMPARE:
    case RTX_COMM_COMPARE:
      if (CONST_INT_P (XEXP (copy, 0))
	  && GET_MODE (XEXP (copy, 1)) == VOIDmode
	  && (GET_MODE (XEXP (orig, 0)) != VOIDmode
	      || GET_MODE (XEXP (orig, 1)) != VOIDmode))
	{
	  scopy = simplify_relational_operation (code, mode,
						 (GET_MODE (XEXP (orig, 0))
						  != VOIDmode)
						 ? GET_MODE (XEXP (orig, 0))
						 : GET_MODE (XEXP (orig, 1)),
						 XEXP (copy, 0),
						 XEXP (copy, 1));
	  if (scopy)
	    return scopy;
	}
      break;
    default:
      break;
    }
  scopy = simplify_rtx (copy);
  if (scopy)
    return scopy;
  return copy;
}

/* Walk rtx X and replace all occurrences of REG and MEM subexpressions
   with VALUE expressions.  This way, it becomes independent of changes
   to registers and memory.
   X isn't actually modified; if modifications are needed, new rtl is
   allocated.  However, the return value can share rtl with X.
   If X is within a MEM, MEMMODE must be the mode of the MEM.  */

rtx
cselib_subst_to_values (rtx x, machine_mode memmode)
{
  enum rtx_code code = GET_CODE (x);
  const char *fmt = GET_RTX_FORMAT (code);
  cselib_val *e;
  struct elt_list *l;
  rtx copy = x;
  int i;

  switch (code)
    {
    case REG:
      l = REG_VALUES (REGNO (x));
      if (l && l->elt == NULL)
	l = l->next;
      for (; l; l = l->next)
	if (GET_MODE (l->elt->val_rtx) == GET_MODE (x))
	  return l->elt->val_rtx;

      gcc_unreachable ();

    case MEM:
      e = cselib_lookup_mem (x, 0);
      /* This used to happen for autoincrements, but we deal with them
	 properly now.  Remove the if stmt for the next release.  */
      if (! e)
	{
	  /* Assign a value that doesn't match any other.  */
	  e = new_cselib_val (next_uid, GET_MODE (x), x);
	}
      return e->val_rtx;

    case ENTRY_VALUE:
      e = cselib_lookup (x, GET_MODE (x), 0, memmode);
      if (! e)
	break;
      return e->val_rtx;

    CASE_CONST_ANY:
      return x;

    case PRE_DEC:
    case PRE_INC:
      gcc_assert (memmode != VOIDmode);
      i = GET_MODE_SIZE (memmode);
      if (code == PRE_DEC)
	i = -i;
      return cselib_subst_to_values (plus_constant (GET_MODE (x),
						    XEXP (x, 0), i),
				     memmode);

    case PRE_MODIFY:
      gcc_assert (memmode != VOIDmode);
      return cselib_subst_to_values (XEXP (x, 1), memmode);

    case POST_DEC:
    case POST_INC:
    case POST_MODIFY:
      gcc_assert (memmode != VOIDmode);
      return cselib_subst_to_values (XEXP (x, 0), memmode);

    default:
      break;
    }

  for (i = GET_RTX_LENGTH (code) - 1; i >= 0; i--)
    {
      if (fmt[i] == 'e')
	{
	  rtx t = cselib_subst_to_values (XEXP (x, i), memmode);

	  if (t != XEXP (x, i))
	    {
	      if (x == copy)
		copy = shallow_copy_rtx (x);
	      XEXP (copy, i) = t;
	    }
	}
      else if (fmt[i] == 'E')
	{
	  int j;

	  for (j = 0; j < XVECLEN (x, i); j++)
	    {
	      rtx t = cselib_subst_to_values (XVECEXP (x, i, j), memmode);

	      if (t != XVECEXP (x, i, j))
		{
		  if (XVEC (x, i) == XVEC (copy, i))
		    {
		      if (x == copy)
			copy = shallow_copy_rtx (x);
		      XVEC (copy, i) = shallow_copy_rtvec (XVEC (x, i));
		    }
		  XVECEXP (copy, i, j) = t;
		}
	    }
	}
    }

  return copy;
}

/* Wrapper for cselib_subst_to_values, that indicates X is in INSN.  */

rtx
cselib_subst_to_values_from_insn (rtx x, machine_mode memmode, rtx_insn *insn)
{
  rtx ret;
  gcc_assert (!cselib_current_insn);
  cselib_current_insn = insn;
  ret = cselib_subst_to_values (x, memmode);
  cselib_current_insn = NULL;
  return ret;
}

/* Look up the rtl expression X in our tables and return the value it
   has.  If CREATE is zero, we return NULL if we don't know the value.
   Otherwise, we create a new one if possible, using mode MODE if X
   doesn't have a mode (i.e. because it's a constant).  When X is part
   of an address, MEMMODE should be the mode of the enclosing MEM if
   we're tracking autoinc expressions.  */

static cselib_val *
cselib_lookup_1 (rtx x, machine_mode mode,
		 int create, machine_mode memmode)
{
  cselib_val **slot;
  cselib_val *e;
  unsigned int hashval;

  if (GET_MODE (x) != VOIDmode)
    mode = GET_MODE (x);

  if (GET_CODE (x) == VALUE)
    return CSELIB_VAL_PTR (x);

  if (REG_P (x))
    {
      struct elt_list *l;
      unsigned int i = REGNO (x);

      l = REG_VALUES (i);
      if (l && l->elt == NULL)
	l = l->next;
      for (; l; l = l->next)
	if (mode == GET_MODE (l->elt->val_rtx))
	  {
	    promote_debug_loc (l->elt->locs);
	    return l->elt;
	  }

      if (! create)
	return 0;

      if (i < FIRST_PSEUDO_REGISTER)
	{
	  unsigned int n = hard_regno_nregs[i][mode];

	  if (n > max_value_regs)
	    max_value_regs = n;
	}

      e = new_cselib_val (next_uid, GET_MODE (x), x);
      new_elt_loc_list (e, x);
      if (REG_VALUES (i) == 0)
	{
	  /* Maintain the invariant that the first entry of
	     REG_VALUES, if present, must be the value used to set the
	     register, or NULL.  */
	  used_regs[n_used_regs++] = i;
	  REG_VALUES (i) = new_elt_list (REG_VALUES (i), NULL);
	}
      else if (cselib_preserve_constants
	       && GET_MODE_CLASS (mode) == MODE_INT)
	{
	  /* During var-tracking, try harder to find equivalences
	     for SUBREGs.  If a setter sets say a DImode register
	     and user uses that register only in SImode, add a lowpart
	     subreg location.  */
	  struct elt_list *lwider = NULL;
	  l = REG_VALUES (i);
	  if (l && l->elt == NULL)
	    l = l->next;
	  for (; l; l = l->next)
	    if (GET_MODE_CLASS (GET_MODE (l->elt->val_rtx)) == MODE_INT
		&& GET_MODE_SIZE (GET_MODE (l->elt->val_rtx))
		   > GET_MODE_SIZE (mode)
		&& (lwider == NULL
		    || GET_MODE_SIZE (GET_MODE (l->elt->val_rtx))
		       < GET_MODE_SIZE (GET_MODE (lwider->elt->val_rtx))))
	      {
		struct elt_loc_list *el;
		if (i < FIRST_PSEUDO_REGISTER
		    && hard_regno_nregs[i][GET_MODE (l->elt->val_rtx)] != 1)
		  continue;
		for (el = l->elt->locs; el; el = el->next)
		  if (!REG_P (el->loc))
		    break;
		if (el)
		  lwider = l;
	      }
	  if (lwider)
	    {
	      rtx sub = lowpart_subreg (mode, lwider->elt->val_rtx,
					GET_MODE (lwider->elt->val_rtx));
	      if (sub)
		new_elt_loc_list (e, sub);
	    }
	}
      REG_VALUES (i)->next = new_elt_list (REG_VALUES (i)->next, e);
      slot = cselib_find_slot (mode, x, e->hash, INSERT, memmode);
      *slot = e;
      return e;
    }

  if (MEM_P (x))
    return cselib_lookup_mem (x, create);

  hashval = cselib_hash_rtx (x, create, memmode);
  /* Can't even create if hashing is not possible.  */
  if (! hashval)
    return 0;

  slot = cselib_find_slot (mode, x, hashval,
			   create ? INSERT : NO_INSERT, memmode);
  if (slot == 0)
    return 0;

  e = (cselib_val *) *slot;
  if (e)
    return e;

  e = new_cselib_val (hashval, mode, x);

  /* We have to fill the slot before calling cselib_subst_to_values:
     the hash table is inconsistent until we do so, and
     cselib_subst_to_values will need to do lookups.  */
  *slot = e;
  new_elt_loc_list (e, cselib_subst_to_values (x, memmode));
  return e;
}

/* Wrapper for cselib_lookup, that indicates X is in INSN.  */

cselib_val *
cselib_lookup_from_insn (rtx x, machine_mode mode,
			 int create, machine_mode memmode, rtx_insn *insn)
{
  cselib_val *ret;

  gcc_assert (!cselib_current_insn);
  cselib_current_insn = insn;

  ret = cselib_lookup (x, mode, create, memmode);

  cselib_current_insn = NULL;

  return ret;
}

/* Wrapper for cselib_lookup_1, that logs the lookup result and
   maintains invariants related with debug insns.  */

cselib_val *
cselib_lookup (rtx x, machine_mode mode,
	       int create, machine_mode memmode)
{
  cselib_val *ret = cselib_lookup_1 (x, mode, create, memmode);

  /* ??? Should we return NULL if we're not to create an entry, the
     found loc is a debug loc and cselib_current_insn is not DEBUG?
     If so, we should also avoid converting val to non-DEBUG; probably
     easiest setting cselib_current_insn to NULL before the call
     above.  */

  if (dump_file && (dump_flags & TDF_CSELIB))
    {
      fputs ("cselib lookup ", dump_file);
      print_inline_rtx (dump_file, x, 2);
      fprintf (dump_file, " => %u:%u\n",
	       ret ? ret->uid : 0,
	       ret ? ret->hash : 0);
    }

  return ret;
}

/* Invalidate any entries in reg_values that overlap REGNO.  This is called
   if REGNO is changing.  MODE is the mode of the assignment to REGNO, which
   is used to determine how many hard registers are being changed.  If MODE
   is VOIDmode, then only REGNO is being changed; this is used when
   invalidating call clobbered registers across a call.  */

static void
cselib_invalidate_regno (unsigned int regno, machine_mode mode)
{
  unsigned int endregno;
  unsigned int i;

  /* If we see pseudos after reload, something is _wrong_.  */
  gcc_assert (!reload_completed || regno < FIRST_PSEUDO_REGISTER
	      || reg_renumber[regno] < 0);

  /* Determine the range of registers that must be invalidated.  For
     pseudos, only REGNO is affected.  For hard regs, we must take MODE
     into account, and we must also invalidate lower register numbers
     if they contain values that overlap REGNO.  */
  if (regno < FIRST_PSEUDO_REGISTER)
    {
      gcc_assert (mode != VOIDmode);

      if (regno < max_value_regs)
	i = 0;
      else
	i = regno - max_value_regs;

      endregno = end_hard_regno (mode, regno);
    }
  else
    {
      i = regno;
      endregno = regno + 1;
    }

  for (; i < endregno; i++)
    {
      struct elt_list **l = &REG_VALUES (i);

      /* Go through all known values for this reg; if it overlaps the range
	 we're invalidating, remove the value.  */
      while (*l)
	{
	  cselib_val *v = (*l)->elt;
	  bool had_locs;
	  rtx_insn *setting_insn;
	  struct elt_loc_list **p;
	  unsigned int this_last = i;

	  if (i < FIRST_PSEUDO_REGISTER && v != NULL)
	    this_last = end_hard_regno (GET_MODE (v->val_rtx), i) - 1;

	  if (this_last < regno || v == NULL
	      || (v == cfa_base_preserved_val
		  && i == cfa_base_preserved_regno))
	    {
	      l = &(*l)->next;
	      continue;
	    }

	  /* We have an overlap.  */
	  if (*l == REG_VALUES (i))
	    {
	      /* Maintain the invariant that the first entry of
		 REG_VALUES, if present, must be the value used to set
		 the register, or NULL.  This is also nice because
		 then we won't push the same regno onto user_regs
		 multiple times.  */
	      (*l)->elt = NULL;
	      l = &(*l)->next;
	    }
	  else
	    unchain_one_elt_list (l);

	  v = canonical_cselib_val (v);

	  had_locs = v->locs != NULL;
	  setting_insn = v->locs ? v->locs->setting_insn : NULL;

	  /* Now, we clear the mapping from value to reg.  It must exist, so
	     this code will crash intentionally if it doesn't.  */
	  for (p = &v->locs; ; p = &(*p)->next)
	    {
	      rtx x = (*p)->loc;

	      if (REG_P (x) && REGNO (x) == i)
		{
		  unchain_one_elt_loc_list (p);
		  break;
		}
	    }

	  if (had_locs && v->locs == 0 && !PRESERVED_VALUE_P (v->val_rtx))
	    {
	      if (setting_insn && DEBUG_INSN_P (setting_insn))
		n_useless_debug_values++;
	      else
		n_useless_values++;
	    }
	}
    }
}

/* Invalidate any locations in the table which are changed because of a
   store to MEM_RTX.  If this is called because of a non-const call
   instruction, MEM_RTX is (mem:BLK const0_rtx).  */

static void
cselib_invalidate_mem (rtx mem_rtx)
{
  cselib_val **vp, *v, *next;
  int num_mems = 0;
  rtx mem_addr;

  mem_addr = canon_rtx (get_addr (XEXP (mem_rtx, 0)));
  mem_rtx = canon_rtx (mem_rtx);

  vp = &first_containing_mem;
  for (v = *vp; v != &dummy_val; v = next)
    {
      bool has_mem = false;
      struct elt_loc_list **p = &v->locs;
      bool had_locs = v->locs != NULL;
      rtx_insn *setting_insn = v->locs ? v->locs->setting_insn : NULL;

      while (*p)
	{
	  rtx x = (*p)->loc;
	  cselib_val *addr;
	  struct elt_list **mem_chain;

	  /* MEMs may occur in locations only at the top level; below
	     that every MEM or REG is substituted by its VALUE.  */
	  if (!MEM_P (x))
	    {
	      p = &(*p)->next;
	      continue;
	    }
	  if (num_mems < PARAM_VALUE (PARAM_MAX_CSELIB_MEMORY_LOCATIONS)
	      && ! canon_anti_dependence (x, false, mem_rtx,
					  GET_MODE (mem_rtx), mem_addr))
	    {
	      has_mem = true;
	      num_mems++;
	      p = &(*p)->next;
	      continue;
	    }

	  /* This one overlaps.  */
	  /* We must have a mapping from this MEM's address to the
	     value (E).  Remove that, too.  */
	  addr = cselib_lookup (XEXP (x, 0), VOIDmode, 0, GET_MODE (x));
	  addr = canonical_cselib_val (addr);
	  gcc_checking_assert (v == canonical_cselib_val (v));
	  mem_chain = &addr->addr_list;
	  for (;;)
	    {
	      cselib_val *canon = canonical_cselib_val ((*mem_chain)->elt);

	      if (canon == v)
		{
		  unchain_one_elt_list (mem_chain);
		  break;
		}

	      /* Record canonicalized elt.  */
	      (*mem_chain)->elt = canon;

	      mem_chain = &(*mem_chain)->next;
	    }

	  unchain_one_elt_loc_list (p);
	}

      if (had_locs && v->locs == 0 && !PRESERVED_VALUE_P (v->val_rtx))
	{
	  if (setting_insn && DEBUG_INSN_P (setting_insn))
	    n_useless_debug_values++;
	  else
	    n_useless_values++;
	}

      next = v->next_containing_mem;
      if (has_mem)
	{
	  *vp = v;
	  vp = &(*vp)->next_containing_mem;
	}
      else
	v->next_containing_mem = NULL;
    }
  *vp = &dummy_val;
}

/* Invalidate DEST, which is being assigned to or clobbered.  */

void
cselib_invalidate_rtx (rtx dest)
{
  while (GET_CODE (dest) == SUBREG
	 || GET_CODE (dest) == ZERO_EXTRACT
	 || GET_CODE (dest) == STRICT_LOW_PART)
    dest = XEXP (dest, 0);

  if (REG_P (dest))
    cselib_invalidate_regno (REGNO (dest), GET_MODE (dest));
  else if (MEM_P (dest))
    cselib_invalidate_mem (dest);
}

/* A wrapper for cselib_invalidate_rtx to be called via note_stores.  */

static void
cselib_invalidate_rtx_note_stores (rtx dest, const_rtx ignore ATTRIBUTE_UNUSED,
				   void *data ATTRIBUTE_UNUSED)
{
  cselib_invalidate_rtx (dest);
}

/* Record the result of a SET instruction.  DEST is being set; the source
   contains the value described by SRC_ELT.  If DEST is a MEM, DEST_ADDR_ELT
   describes its address.  */

static void
cselib_record_set (rtx dest, cselib_val *src_elt, cselib_val *dest_addr_elt)
{
  if (src_elt == 0 || side_effects_p (dest))
    return;

  if (REG_P (dest))
    {
      unsigned int dreg = REGNO (dest);
      if (dreg < FIRST_PSEUDO_REGISTER)
	{
	  unsigned int n = REG_NREGS (dest);

	  if (n > max_value_regs)
	    max_value_regs = n;
	}

      if (REG_VALUES (dreg) == 0)
	{
	  used_regs[n_used_regs++] = dreg;
	  REG_VALUES (dreg) = new_elt_list (REG_VALUES (dreg), src_elt);
	}
      else
	{
	  /* The register should have been invalidated.  */
	  gcc_assert (REG_VALUES (dreg)->elt == 0);
	  REG_VALUES (dreg)->elt = src_elt;
	}

      if (src_elt->locs == 0 && !PRESERVED_VALUE_P (src_elt->val_rtx))
	n_useless_values--;
      new_elt_loc_list (src_elt, dest);
    }
  else if (MEM_P (dest) && dest_addr_elt != 0
	   && cselib_record_memory)
    {
      if (src_elt->locs == 0 && !PRESERVED_VALUE_P (src_elt->val_rtx))
	n_useless_values--;
      add_mem_for_addr (dest_addr_elt, src_elt, dest);
    }
}

/* Make ELT and X's VALUE equivalent to each other at INSN.  */

void
cselib_add_permanent_equiv (cselib_val *elt, rtx x, rtx_insn *insn)
{
  cselib_val *nelt;
  rtx_insn *save_cselib_current_insn = cselib_current_insn;

  gcc_checking_assert (elt);
  gcc_checking_assert (PRESERVED_VALUE_P (elt->val_rtx));
  gcc_checking_assert (!side_effects_p (x));

  cselib_current_insn = insn;

  nelt = cselib_lookup (x, GET_MODE (elt->val_rtx), 1, VOIDmode);

  if (nelt != elt)
    {
      cselib_any_perm_equivs = true;

      if (!PRESERVED_VALUE_P (nelt->val_rtx))
	cselib_preserve_value (nelt);

      new_elt_loc_list (nelt, elt->val_rtx);
    }

  cselib_current_insn = save_cselib_current_insn;
}

/* Return TRUE if any permanent equivalences have been recorded since
   the table was last initialized.  */
bool
cselib_have_permanent_equivalences (void)
{
  return cselib_any_perm_equivs;
}

/* There is no good way to determine how many elements there can be
   in a PARALLEL.  Since it's fairly cheap, use a really large number.  */
#define MAX_SETS (FIRST_PSEUDO_REGISTER * 2)

struct cselib_record_autoinc_data
{
  struct cselib_set *sets;
  int n_sets;
};

/* Callback for for_each_inc_dec.  Records in ARG the SETs implied by
   autoinc RTXs: SRC plus SRCOFF if non-NULL is stored in DEST.  */

static int
cselib_record_autoinc_cb (rtx mem ATTRIBUTE_UNUSED, rtx op ATTRIBUTE_UNUSED,
			  rtx dest, rtx src, rtx srcoff, void *arg)
{
  struct cselib_record_autoinc_data *data;
  data = (struct cselib_record_autoinc_data *)arg;

  data->sets[data->n_sets].dest = dest;

  if (srcoff)
    data->sets[data->n_sets].src = gen_rtx_PLUS (GET_MODE (src), src, srcoff);
  else
    data->sets[data->n_sets].src = src;

  data->n_sets++;

  return 0;
}

/* Record the effects of any sets and autoincs in INSN.  */
static void
cselib_record_sets (rtx_insn *insn)
{
  int n_sets = 0;
  int i;
  struct cselib_set sets[MAX_SETS];
  rtx body = PATTERN (insn);
  rtx cond = 0;
  int n_sets_before_autoinc;
  struct cselib_record_autoinc_data data;

  body = PATTERN (insn);
  if (GET_CODE (body) == COND_EXEC)
    {
      cond = COND_EXEC_TEST (body);
      body = COND_EXEC_CODE (body);
    }

  /* Find all sets.  */
  if (GET_CODE (body) == SET)
    {
      sets[0].src = SET_SRC (body);
      sets[0].dest = SET_DEST (body);
      n_sets = 1;
    }
  else if (GET_CODE (body) == PARALLEL)
    {
      /* Look through the PARALLEL and record the values being
	 set, if possible.  Also handle any CLOBBERs.  */
      for (i = XVECLEN (body, 0) - 1; i >= 0; --i)
	{
	  rtx x = XVECEXP (body, 0, i);

	  if (GET_CODE (x) == SET)
	    {
	      sets[n_sets].src = SET_SRC (x);
	      sets[n_sets].dest = SET_DEST (x);
	      n_sets++;
	    }
	}
    }

  if (n_sets == 1
      && MEM_P (sets[0].src)
      && !cselib_record_memory
      && MEM_READONLY_P (sets[0].src))
    {
      rtx note = find_reg_equal_equiv_note (insn);

      if (note && CONSTANT_P (XEXP (note, 0)))
	sets[0].src = XEXP (note, 0);
    }

  data.sets = sets;
  data.n_sets = n_sets_before_autoinc = n_sets;
  for_each_inc_dec (PATTERN (insn), cselib_record_autoinc_cb, &data);
  n_sets = data.n_sets;

  /* Look up the values that are read.  Do this before invalidating the
     locations that are written.  */
  for (i = 0; i < n_sets; i++)
    {
      rtx dest = sets[i].dest;

      /* A STRICT_LOW_PART can be ignored; we'll record the equivalence for
         the low part after invalidating any knowledge about larger modes.  */
      if (GET_CODE (sets[i].dest) == STRICT_LOW_PART)
	sets[i].dest = dest = XEXP (dest, 0);

      /* We don't know how to record anything but REG or MEM.  */
      if (REG_P (dest)
	  || (MEM_P (dest) && cselib_record_memory))
        {
	  rtx src = sets[i].src;
	  if (cond)
	    src = gen_rtx_IF_THEN_ELSE (GET_MODE (dest), cond, src, dest);
	  sets[i].src_elt = cselib_lookup (src, GET_MODE (dest), 1, VOIDmode);
	  if (MEM_P (dest))
	    {
	      machine_mode address_mode = get_address_mode (dest);

	      sets[i].dest_addr_elt = cselib_lookup (XEXP (dest, 0),
						     address_mode, 1,
						     GET_MODE (dest));
	    }
	  else
	    sets[i].dest_addr_elt = 0;
	}
    }

  if (cselib_record_sets_hook)
    cselib_record_sets_hook (insn, sets, n_sets);

  /* Invalidate all locations written by this insn.  Note that the elts we
     looked up in the previous loop aren't affected, just some of their
     locations may go away.  */
  note_stores (body, cselib_invalidate_rtx_note_stores, NULL);

  for (i = n_sets_before_autoinc; i < n_sets; i++)
    cselib_invalidate_rtx (sets[i].dest);

  /* If this is an asm, look for duplicate sets.  This can happen when the
     user uses the same value as an output multiple times.  This is valid
     if the outputs are not actually used thereafter.  Treat this case as
     if the value isn't actually set.  We do this by smashing the destination
     to pc_rtx, so that we won't record the value later.  */
  if (n_sets >= 2 && asm_noperands (body) >= 0)
    {
      for (i = 0; i < n_sets; i++)
	{
	  rtx dest = sets[i].dest;
	  if (REG_P (dest) || MEM_P (dest))
	    {
	      int j;
	      for (j = i + 1; j < n_sets; j++)
		if (rtx_equal_p (dest, sets[j].dest))
		  {
		    sets[i].dest = pc_rtx;
		    sets[j].dest = pc_rtx;
		  }
	    }
	}
    }

  /* Now enter the equivalences in our tables.  */
  for (i = 0; i < n_sets; i++)
    {
      rtx dest = sets[i].dest;
      if (REG_P (dest)
	  || (MEM_P (dest) && cselib_record_memory))
	cselib_record_set (dest, sets[i].src_elt, sets[i].dest_addr_elt);
    }
}

/* Return true if INSN in the prologue initializes hard_frame_pointer_rtx.  */

bool
fp_setter_insn (rtx_insn *insn)
{
  rtx expr, pat = NULL_RTX;

  if (!RTX_FRAME_RELATED_P (insn))
    return false;

  expr = find_reg_note (insn, REG_FRAME_RELATED_EXPR, NULL_RTX);
  if (expr)
    pat = XEXP (expr, 0);
  if (!modified_in_p (hard_frame_pointer_rtx, pat ? pat : insn))
    return false;

  /* Don't return true for frame pointer restores in the epilogue.  */
  if (find_reg_note (insn, REG_CFA_RESTORE, hard_frame_pointer_rtx))
    return false;
  return true;
}

/* Record the effects of INSN.  */

void
cselib_process_insn (rtx_insn *insn)
{
  int i;
  rtx x;

  cselib_current_insn = insn;

  /* Forget everything at a CODE_LABEL or a setjmp.  */
  if ((LABEL_P (insn)
       || (CALL_P (insn)
	   && find_reg_note (insn, REG_SETJMP, NULL)))
      && !cselib_preserve_constants)
    {
      cselib_reset_table (next_uid);
      cselib_current_insn = NULL;
      return;
    }

  if (! INSN_P (insn))
    {
      cselib_current_insn = NULL;
      return;
    }

  /* If this is a call instruction, forget anything stored in a
     call clobbered register, or, if this is not a const call, in
     memory.  */
  if (CALL_P (insn))
    {
      for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
	if (call_used_regs[i]
	    || (REG_VALUES (i) && REG_VALUES (i)->elt
		&& HARD_REGNO_CALL_PART_CLOBBERED (i,
		      GET_MODE (REG_VALUES (i)->elt->val_rtx))))
	  cselib_invalidate_regno (i, reg_raw_mode[i]);

      /* Since it is not clear how cselib is going to be used, be
	 conservative here and treat looping pure or const functions
	 as if they were regular functions.  */
      if (RTL_LOOPING_CONST_OR_PURE_CALL_P (insn)
	  || !(RTL_CONST_OR_PURE_CALL_P (insn)))
	cselib_invalidate_mem (callmem);
      else
	/* For const/pure calls, invalidate any argument slots because
	   they are owned by the callee.  */
	for (x = CALL_INSN_FUNCTION_USAGE (insn); x; x = XEXP (x, 1))
	  if (GET_CODE (XEXP (x, 0)) == USE
	      && MEM_P (XEXP (XEXP (x, 0), 0)))
	    cselib_invalidate_mem (XEXP (XEXP (x, 0), 0));
    }

  cselib_record_sets (insn);

  /* Look for any CLOBBERs in CALL_INSN_FUNCTION_USAGE, but only
     after we have processed the insn.  */
  if (CALL_P (insn))
    {
      for (x = CALL_INSN_FUNCTION_USAGE (insn); x; x = XEXP (x, 1))
	if (GET_CODE (XEXP (x, 0)) == CLOBBER)
	  cselib_invalidate_rtx (XEXP (XEXP (x, 0), 0));
      /* Flush evertything on setjmp.  */
      if (cselib_preserve_constants
	  && find_reg_note (insn, REG_SETJMP, NULL))
	{
	  cselib_preserve_only_values ();
	  cselib_reset_table (next_uid);
	}
    }

  /* On setter of the hard frame pointer if frame_pointer_needed,
     invalidate stack_pointer_rtx, so that sp and {,h}fp based
     VALUEs are distinct.  */
  if (reload_completed
      && frame_pointer_needed
      && fp_setter_insn (insn))
    cselib_invalidate_rtx (stack_pointer_rtx);

  cselib_current_insn = NULL;

  if (n_useless_values > MAX_USELESS_VALUES
      /* remove_useless_values is linear in the hash table size.  Avoid
         quadratic behavior for very large hashtables with very few
	 useless elements.  */
      && ((unsigned int)n_useless_values
	  > (cselib_hash_table->elements () - n_debug_values) / 4))
    remove_useless_values ();
}

/* Initialize cselib for one pass.  The caller must also call
   init_alias_analysis.  */

void
cselib_init (int record_what)
{
  cselib_record_memory = record_what & CSELIB_RECORD_MEMORY;
  cselib_preserve_constants = record_what & CSELIB_PRESERVE_CONSTANTS;
  cselib_any_perm_equivs = false;

  /* (mem:BLK (scratch)) is a special mechanism to conflict with everything,
     see canon_true_dependence.  This is only created once.  */
  if (! callmem)
    callmem = gen_rtx_MEM (BLKmode, gen_rtx_SCRATCH (VOIDmode));

  cselib_nregs = max_reg_num ();

  /* We preserve reg_values to allow expensive clearing of the whole thing.
     Reallocate it however if it happens to be too large.  */
  if (!reg_values || reg_values_size < cselib_nregs
      || (reg_values_size > 10 && reg_values_size > cselib_nregs * 4))
    {
      free (reg_values);
      /* Some space for newly emit instructions so we don't end up
	 reallocating in between passes.  */
      reg_values_size = cselib_nregs + (63 + cselib_nregs) / 16;
      reg_values = XCNEWVEC (struct elt_list *, reg_values_size);
    }
  used_regs = XNEWVEC (unsigned int, cselib_nregs);
  n_used_regs = 0;
  cselib_hash_table = new hash_table<cselib_hasher> (31);
  if (cselib_preserve_constants)
    cselib_preserved_hash_table = new hash_table<cselib_hasher> (31);
  next_uid = 1;
}

/* Called when the current user is done with cselib.  */

void
cselib_finish (void)
{
  bool preserved = cselib_preserve_constants;
  cselib_discard_hook = NULL;
  cselib_preserve_constants = false;
  cselib_any_perm_equivs = false;
  cfa_base_preserved_val = NULL;
  cfa_base_preserved_regno = INVALID_REGNUM;
  elt_list_pool.release ();
  elt_loc_list_pool.release ();
  cselib_val_pool.release ();
  value_pool.release ();
  cselib_clear_table ();
  delete cselib_hash_table;
  cselib_hash_table = NULL;
  if (preserved)
    delete cselib_preserved_hash_table;
  cselib_preserved_hash_table = NULL;
  free (used_regs);
  used_regs = 0;
  n_useless_values = 0;
  n_useless_debug_values = 0;
  n_debug_values = 0;
  next_uid = 0;
}

/* Dump the cselib_val *X to FILE *OUT.  */

int
dump_cselib_val (cselib_val **x, FILE *out)
{
  cselib_val *v = *x;
  bool need_lf = true;

  print_inline_rtx (out, v->val_rtx, 0);

  if (v->locs)
    {
      struct elt_loc_list *l = v->locs;
      if (need_lf)
	{
	  fputc ('\n', out);
	  need_lf = false;
	}
      fputs (" locs:", out);
      do
	{
	  if (l->setting_insn)
	    fprintf (out, "\n  from insn %i ",
		     INSN_UID (l->setting_insn));
	  else
	    fprintf (out, "\n   ");
	  print_inline_rtx (out, l->loc, 4);
	}
      while ((l = l->next));
      fputc ('\n', out);
    }
  else
    {
      fputs (" no locs", out);
      need_lf = true;
    }

  if (v->addr_list)
    {
      struct elt_list *e = v->addr_list;
      if (need_lf)
	{
	  fputc ('\n', out);
	  need_lf = false;
	}
      fputs (" addr list:", out);
      do
	{
	  fputs ("\n  ", out);
	  print_inline_rtx (out, e->elt->val_rtx, 2);
	}
      while ((e = e->next));
      fputc ('\n', out);
    }
  else
    {
      fputs (" no addrs", out);
      need_lf = true;
    }

  if (v->next_containing_mem == &dummy_val)
    fputs (" last mem\n", out);
  else if (v->next_containing_mem)
    {
      fputs (" next mem ", out);
      print_inline_rtx (out, v->next_containing_mem->val_rtx, 2);
      fputc ('\n', out);
    }
  else if (need_lf)
    fputc ('\n', out);

  return 1;
}

/* Dump to OUT everything in the CSELIB table.  */

void
dump_cselib_table (FILE *out)
{
  fprintf (out, "cselib hash table:\n");
  cselib_hash_table->traverse <FILE *, dump_cselib_val> (out);
  fprintf (out, "cselib preserved hash table:\n");
  cselib_preserved_hash_table->traverse <FILE *, dump_cselib_val> (out);
  if (first_containing_mem != &dummy_val)
    {
      fputs ("first mem ", out);
      print_inline_rtx (out, first_containing_mem->val_rtx, 2);
      fputc ('\n', out);
    }
  fprintf (out, "next uid %i\n", next_uid);
}

#include "gt-cselib.h"