aboutsummaryrefslogtreecommitdiff
path: root/gcc/bitmap.cc
blob: 0905cde696fd90d80b1bfe0100167fb2b2e5f21f (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
2867
2868
2869
2870
2871
2872
2873
2874
2875
2876
2877
2878
2879
2880
2881
2882
2883
2884
2885
2886
2887
2888
2889
2890
2891
2892
2893
2894
2895
2896
2897
2898
2899
2900
2901
2902
2903
2904
2905
2906
2907
2908
2909
2910
2911
2912
2913
2914
2915
2916
2917
2918
2919
2920
2921
2922
2923
2924
2925
2926
2927
2928
2929
2930
2931
2932
2933
2934
2935
2936
2937
2938
2939
2940
2941
2942
2943
2944
2945
2946
2947
2948
2949
2950
2951
2952
2953
2954
2955
2956
2957
2958
2959
2960
2961
2962
2963
2964
2965
2966
2967
2968
2969
2970
2971
2972
2973
2974
2975
2976
2977
2978
2979
2980
2981
2982
2983
2984
2985
2986
2987
2988
2989
2990
2991
2992
2993
2994
2995
2996
2997
2998
2999
3000
3001
3002
3003
3004
3005
3006
3007
3008
3009
3010
3011
3012
3013
3014
3015
3016
3017
3018
3019
3020
3021
3022
3023
3024
3025
3026
3027
3028
3029
3030
3031
/* Functions to support general ended bitmaps.
   Copyright (C) 1997-2024 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 "bitmap.h"
#include "selftest.h"

/* Memory allocation statistics purpose instance.  */
mem_alloc_description<bitmap_usage> bitmap_mem_desc;

/* Static zero-initialized bitmap obstack used for default initialization
   of bitmap_head.  */
bitmap_obstack bitmap_head::crashme;

static bitmap_element *bitmap_tree_listify_from (bitmap, bitmap_element *);

/* Register new bitmap.  */
void
bitmap_register (bitmap b MEM_STAT_DECL)
{
  static unsigned alloc_descriptor_max_uid = 1;
  gcc_assert (b->alloc_descriptor == 0);
  b->alloc_descriptor = alloc_descriptor_max_uid++;

  bitmap_mem_desc.register_descriptor (b->get_descriptor (), BITMAP_ORIGIN,
				       false FINAL_PASS_MEM_STAT);
}

/* Account the overhead.  */
static void
register_overhead (bitmap b, size_t amount)
{
  unsigned *d = b->get_descriptor ();
  if (bitmap_mem_desc.contains_descriptor_for_instance (d))
    bitmap_mem_desc.register_instance_overhead (amount, d);
}

/* Release the overhead.  */
static void
release_overhead (bitmap b, size_t amount, bool remove_from_map)
{
  unsigned *d = b->get_descriptor ();
  if (bitmap_mem_desc.contains_descriptor_for_instance (d))
    bitmap_mem_desc.release_instance_overhead (d, amount, remove_from_map);
}


/* Global data */
bitmap_element bitmap_zero_bits;  /* An element of all zero bits.  */
bitmap_obstack bitmap_default_obstack;    /* The default bitmap obstack.  */
static int bitmap_default_obstack_depth;
static GTY((deletable)) bitmap_element *bitmap_ggc_free; /* Freelist of
							    GC'd elements.  */


/* Bitmap memory management.  */

/* Add ELT to the appropriate freelist.  */
static inline void
bitmap_elem_to_freelist (bitmap head, bitmap_element *elt)
{
  bitmap_obstack *bit_obstack = head->obstack;

  if (GATHER_STATISTICS)
    release_overhead (head, sizeof (bitmap_element), false);

  elt->next = NULL;
  elt->indx = -1;
  if (bit_obstack)
    {
      elt->prev = bit_obstack->elements;
      bit_obstack->elements = elt;
    }
  else
    {
      elt->prev = bitmap_ggc_free;
      bitmap_ggc_free = elt;
    }
}

/* Allocate a bitmap element.  The bits are cleared, but nothing else is.  */

static inline bitmap_element *
bitmap_element_allocate (bitmap head)
{
  bitmap_element *element;
  bitmap_obstack *bit_obstack = head->obstack;

  if (bit_obstack)
    {
      element = bit_obstack->elements;

      if (element)
	/* Use up the inner list first before looking at the next
	   element of the outer list.  */
	if (element->next)
	  {
	    bit_obstack->elements = element->next;
	    bit_obstack->elements->prev = element->prev;
	  }
	else
	  /*  Inner list was just a singleton.  */
	  bit_obstack->elements = element->prev;
      else
	element = XOBNEW (&bit_obstack->obstack, bitmap_element);
    }
  else
    {
      element = bitmap_ggc_free;
      if (element)
	/* Use up the inner list first before looking at the next
	   element of the outer list.  */
	if (element->next)
	  {
	    bitmap_ggc_free = element->next;
	    bitmap_ggc_free->prev = element->prev;
	  }
	else
	  /*  Inner list was just a singleton.  */
	  bitmap_ggc_free = element->prev;
      else
	element = ggc_alloc<bitmap_element> ();
    }

  if (GATHER_STATISTICS)
    register_overhead (head, sizeof (bitmap_element));

  memset (element->bits, 0, sizeof (element->bits));

  return element;
}

/* Remove ELT and all following elements from bitmap HEAD.
   Put the released elements in the freelist for HEAD.  */

void
bitmap_elt_clear_from (bitmap head, bitmap_element *elt)
{
  bitmap_element *prev;
  bitmap_obstack *bit_obstack = head->obstack;

  if (!elt)
    return;

  if (head->tree_form)
    elt = bitmap_tree_listify_from (head, elt);

  if (GATHER_STATISTICS)
    {
      int n = 0;
      for (prev = elt; prev; prev = prev->next)
	n++;
      release_overhead (head, sizeof (bitmap_element) * n, false);
    }

  prev = elt->prev;
  if (prev)
    {
      prev->next = NULL;
      if (head->current->indx > prev->indx)
	{
	  head->current = prev;
	  head->indx = prev->indx;
	}
    }
  else
    {
      head->first = NULL;
      head->current = NULL;
      head->indx = 0;
    }

  /* Put the entire list onto the freelist in one operation. */
  if (bit_obstack)
    {
      elt->prev = bit_obstack->elements;
      bit_obstack->elements = elt;
    }
  else
    {
      elt->prev = bitmap_ggc_free;
      bitmap_ggc_free = elt;
    }
}

/* Linked-list view of bitmaps.

   In this representation, the bitmap elements form a double-linked list
   with elements sorted by increasing index.  */

/* Link the bitmap element into the current bitmap linked list.  */

static inline void
bitmap_list_link_element (bitmap head, bitmap_element *element)
{
  unsigned int indx = element->indx;
  bitmap_element *ptr;

  gcc_checking_assert (!head->tree_form);

  /* If this is the first and only element, set it in.  */
  if (head->first == 0)
    {
      element->next = element->prev = 0;
      head->first = element;
    }

  /* If this index is less than that of the current element, it goes someplace
     before the current element.  */
  else if (indx < head->indx)
    {
      for (ptr = head->current;
	   ptr->prev != 0 && ptr->prev->indx > indx;
	   ptr = ptr->prev)
	;

      if (ptr->prev)
	ptr->prev->next = element;
      else
	head->first = element;

      element->prev = ptr->prev;
      element->next = ptr;
      ptr->prev = element;
    }

  /* Otherwise, it must go someplace after the current element.  */
  else
    {
      for (ptr = head->current;
	   ptr->next != 0 && ptr->next->indx < indx;
	   ptr = ptr->next)
	;

      if (ptr->next)
	ptr->next->prev = element;

      element->next = ptr->next;
      element->prev = ptr;
      ptr->next = element;
    }

  /* Set up so this is the first element searched.  */
  head->current = element;
  head->indx = indx;
}

/* Unlink the bitmap element from the current bitmap linked list,
   and return it to the freelist.  */

static inline void
bitmap_list_unlink_element (bitmap head, bitmap_element *element,
			    bool to_freelist = true)
{
  bitmap_element *next = element->next;
  bitmap_element *prev = element->prev;

  gcc_checking_assert (!head->tree_form);

  if (prev)
    prev->next = next;

  if (next)
    next->prev = prev;

  if (head->first == element)
    head->first = next;

  /* Since the first thing we try is to insert before current,
     make current the next entry in preference to the previous.  */
  if (head->current == element)
    {
      head->current = next != 0 ? next : prev;
      if (head->current)
	head->indx = head->current->indx;
      else
	head->indx = 0;
    }

  if (to_freelist)
    bitmap_elem_to_freelist (head, element);
}

/* Insert a new uninitialized element (or NODE if not NULL) into bitmap
   HEAD after element ELT.  If ELT is NULL, insert the element at the start.
   Return the new element.  */

static bitmap_element *
bitmap_list_insert_element_after (bitmap head,
				  bitmap_element *elt, unsigned int indx,
				  bitmap_element *node = NULL)
{
  if (!node)
    node = bitmap_element_allocate (head);
  node->indx = indx;

  gcc_checking_assert (!head->tree_form);

  if (!elt)
    {
      if (!head->current)
	{
	  head->current = node;
	  head->indx = indx;
	}
      node->next = head->first;
      if (node->next)
	node->next->prev = node;
      head->first = node;
      node->prev = NULL;
    }
  else
    {
      gcc_checking_assert (head->current);
      node->next = elt->next;
      if (node->next)
	node->next->prev = node;
      elt->next = node;
      node->prev = elt;
    }
  return node;
}

/* Return the element for INDX, or NULL if the element doesn't exist.
   Update the `current' field even if we can't find an element that  
   would hold the bitmap's bit to make eventual allocation
   faster.  */

static inline bitmap_element *
bitmap_list_find_element (bitmap head, unsigned int indx)
{
  bitmap_element *element;

  if (head->current == NULL
      || head->indx == indx)
    return head->current;

  if (head->current == head->first
      && head->first->next == NULL)
    return NULL;

  /* Usage can be NULL due to allocated bitmaps for which we do not
     call initialize function.  */
  bitmap_usage *usage = NULL;
  if (GATHER_STATISTICS)
    usage = bitmap_mem_desc.get_descriptor_for_instance (head);

  /* This bitmap has more than one element, and we're going to look
     through the elements list.  Count that as a search.  */
  if (GATHER_STATISTICS && usage)
    usage->m_nsearches++;

  if (head->indx < indx)
    /* INDX is beyond head->indx.  Search from head->current
       forward.  */
    for (element = head->current;
	 element->next != 0 && element->indx < indx;
	 element = element->next)
      {
	if (GATHER_STATISTICS && usage)
	  usage->m_search_iter++;
      }

  else if (head->indx / 2 < indx)
    /* INDX is less than head->indx and closer to head->indx than to
       0.  Search from head->current backward.  */
    for (element = head->current;
	 element->prev != 0 && element->indx > indx;
	 element = element->prev)
      {
	if (GATHER_STATISTICS && usage)
	  usage->m_search_iter++;
      }

  else
    /* INDX is less than head->indx and closer to 0 than to
       head->indx.  Search from head->first forward.  */
    for (element = head->first;
	 element->next != 0 && element->indx < indx;
	 element = element->next)
      {
	if (GATHER_STATISTICS && usage)
	  usage->m_search_iter++;
      }

  /* `element' is the nearest to the one we want.  If it's not the one we
     want, the one we want doesn't exist.  */
  gcc_checking_assert (element != NULL);
  head->current = element;
  head->indx = element->indx;
  if (element->indx != indx)
    element = 0;
  return element;
}


/* Splay-tree view of bitmaps.

   This is an almost one-to-one the implementatin of the simple top-down
   splay tree in Sleator and Tarjan's "Self-adjusting Binary Search Trees".
   It is probably not the most efficient form of splay trees, but it should
   be good enough to experiment with this idea of bitmaps-as-trees.
   
   For all functions below, the variable or function argument "t" is a node
   in the tree, and "e" is a temporary or new node in the tree.  The rest
   is sufficiently straigh-forward (and very well explained in the paper)
   that comment would only clutter things.  */

static inline void
bitmap_tree_link_left (bitmap_element * &t, bitmap_element * &l)
{
  l->next = t;
  l = t;
  t = t->next;
}

static inline void
bitmap_tree_link_right (bitmap_element * &t, bitmap_element * &r)
{
  r->prev = t;
  r = t;
  t = t->prev;
}

static inline void
bitmap_tree_rotate_left (bitmap_element * &t)
{
  bitmap_element *e = t->next;
  t->next = t->next->prev;
  e->prev = t;
  t = e;
}

static inline void
bitmap_tree_rotate_right (bitmap_element * &t)
{
  bitmap_element *e = t->prev;
  t->prev = t->prev->next;
  e->next = t;
  t = e;
}

static bitmap_element *
bitmap_tree_splay (bitmap head, bitmap_element *t, unsigned int indx)
{
  bitmap_element N, *l, *r;

  if (t == NULL)
    return NULL;

  bitmap_usage *usage = NULL;
  if (GATHER_STATISTICS)
    usage = bitmap_mem_desc.get_descriptor_for_instance (head);

  N.prev = N.next = NULL;
  l = r = &N;

  while (indx != t->indx)
    {
      if (GATHER_STATISTICS && usage)
	usage->m_search_iter++;

      if (indx < t->indx)
	{
	  if (t->prev != NULL && indx < t->prev->indx)
	    bitmap_tree_rotate_right (t);
	  if (t->prev == NULL)
	    break;
	  bitmap_tree_link_right (t, r);
	}
      else if (indx > t->indx)
	{
	  if (t->next != NULL && indx > t->next->indx)
	    bitmap_tree_rotate_left (t);
	  if (t->next == NULL)
	    break;
	  bitmap_tree_link_left (t, l);
	}
    }

  l->next = t->prev;
  r->prev = t->next;
  t->prev = N.next;
  t->next = N.prev;
  return t;
}

/* Link bitmap element E into the current bitmap splay tree.  */

static inline void
bitmap_tree_link_element (bitmap head, bitmap_element *e)
{
  if (head->first == NULL)
    e->prev = e->next = NULL;
  else
    {
      bitmap_element *t = bitmap_tree_splay (head, head->first, e->indx);
      if (e->indx < t->indx)
	{
	  e->prev = t->prev;
	  e->next = t;
	  t->prev = NULL;
	}
      else if (e->indx > t->indx)
	{
	  e->next = t->next;
	  e->prev = t;
	  t->next = NULL;
	}
      else
	gcc_unreachable ();
    }
  head->first = e;
  head->current = e;
  head->indx = e->indx;
}

/* Unlink bitmap element E from the current bitmap splay tree,
   and return it to the freelist.  */

static void
bitmap_tree_unlink_element (bitmap head, bitmap_element *e)
{
  bitmap_element *t = bitmap_tree_splay (head, head->first, e->indx);

  gcc_checking_assert (t == e);

  if (e->prev == NULL)
    t = e->next;
  else
    {
      t = bitmap_tree_splay (head, e->prev, e->indx);
      t->next = e->next;
    }
  head->first = t;
  head->current = t;
  head->indx = (t != NULL) ? t->indx : 0;

  bitmap_elem_to_freelist (head, e);
}

/* Return the element for INDX, or NULL if the element doesn't exist.  */

static inline bitmap_element *
bitmap_tree_find_element (bitmap head, unsigned int indx)
{
  if (head->current == NULL
      || head->indx == indx)
    return head->current;

  /* Usage can be NULL due to allocated bitmaps for which we do not
     call initialize function.  */
  bitmap_usage *usage = NULL;
  if (GATHER_STATISTICS)
    usage = bitmap_mem_desc.get_descriptor_for_instance (head);

  /* This bitmap has more than one element, and we're going to look
     through the elements list.  Count that as a search.  */
  if (GATHER_STATISTICS && usage)
    usage->m_nsearches++;

  bitmap_element *element = bitmap_tree_splay (head, head->first, indx);
  gcc_checking_assert (element != NULL);
  head->first = element;
  head->current = element;
  head->indx = element->indx;
  if (element->indx != indx)
    element = 0;
  return element;
}

/* Converting bitmap views from linked-list to tree and vice versa.  */

/* Splice element E and all elements with a larger index from
   bitmap HEAD, convert the spliced elements to the linked-list
   view, and return the head of the list (which should be E again),  */

static bitmap_element *
bitmap_tree_listify_from (bitmap head, bitmap_element *e)
{
  bitmap_element *t, *erb;

  /* Detach the right branch from E (all elements with indx > E->indx),
     and splay E to the root.  */
  erb = e->next;
  e->next = NULL;
  t = bitmap_tree_splay (head, head->first, e->indx);
  gcc_checking_assert (t == e);

  /* Because E has no right branch, and we rotated it to the root,
     the left branch is the new root.  */
  t = e->prev;
  head->first = t;
  head->current = t;
  head->indx = (t != NULL) ? t->indx : 0;

  /* Detach the tree from E, and re-attach the right branch of E.  */
  e->prev = NULL;
  e->next = erb;

  /* The tree is now valid again.  Now we need to "un-tree" E.
     It is imperative that a non-recursive implementation is used
     for this, because splay trees have a worst case depth of O(N)
     for a tree with N nodes.  A recursive implementation could
     result in a stack overflow for a sufficiently large, unbalanced
     bitmap tree.  */

  auto_vec<bitmap_element *, 32> stack;
  auto_vec<bitmap_element *, 32> sorted_elements;
  bitmap_element *n = e;

  while (true)
    {
      while (n != NULL)
	{
	  stack.safe_push (n);
	  n = n->prev;
	}

      if (stack.is_empty ())
	break;

      n = stack.pop ();
      sorted_elements.safe_push (n);
      n = n->next;
    }

  gcc_assert (sorted_elements[0] == e);

  bitmap_element *prev = NULL;
  unsigned ix;
  FOR_EACH_VEC_ELT (sorted_elements, ix, n)
    {
      if (prev != NULL)
        prev->next = n;
      n->prev = prev;
      n->next = NULL;
      prev = n;
    }

  return e;
}

/* Convert bitmap HEAD from splay-tree view to linked-list view.  */

void
bitmap_list_view (bitmap head)
{
  bitmap_element *ptr;

  gcc_assert (head->tree_form);

  ptr = head->first;
  if (ptr)
    {
      while (ptr->prev)
	bitmap_tree_rotate_right (ptr);
      head->first = ptr;
      head->first = bitmap_tree_listify_from (head, ptr);
    }

  head->tree_form = false;
  if (!head->current)
    {
      head->current = head->first;
      head->indx = head->current ? head->current->indx : 0;
    }
}

/* Convert bitmap HEAD from linked-list view to splay-tree view.
   This is simply a matter of dropping the prev or next pointers
   and setting the tree_form flag.  The tree will balance itself
   if and when it is used.  */

void
bitmap_tree_view (bitmap head)
{
  bitmap_element *ptr;

  gcc_assert (! head->tree_form);

  ptr = head->first;
  while (ptr)
    {
      ptr->prev = NULL;
      ptr = ptr->next;
    }

  head->tree_form = true;
}

/* Clear a bitmap by freeing all its elements.  */

void
bitmap_clear (bitmap head)
{
  if (head->first == NULL)
    return;
  if (head->tree_form)
    {
      bitmap_element *e, *t;
      for (e = head->first; e->prev; e = e->prev)
	/* Loop to find the element with the smallest index.  */ ;
      t = bitmap_tree_splay (head, head->first, e->indx);
      gcc_checking_assert (t == e);
      head->first = t;
    }
  bitmap_elt_clear_from (head, head->first);
}

/* Initialize a bitmap obstack.  If BIT_OBSTACK is NULL, initialize
   the default bitmap obstack.  */

void
bitmap_obstack_initialize (bitmap_obstack *bit_obstack)
{
  if (!bit_obstack)
    {
      if (bitmap_default_obstack_depth++)
	return;
      bit_obstack = &bitmap_default_obstack;
    }

#if !defined(__GNUC__) || (__GNUC__ < 2)
#define __alignof__(type) 0
#endif

  bit_obstack->elements = NULL;
  bit_obstack->heads = NULL;
  obstack_specify_allocation (&bit_obstack->obstack, OBSTACK_CHUNK_SIZE,
			      __alignof__ (bitmap_element),
			      obstack_chunk_alloc,
			      obstack_chunk_free);
}

/* Release the memory from a bitmap obstack.  If BIT_OBSTACK is NULL,
   release the default bitmap obstack.  */

void
bitmap_obstack_release (bitmap_obstack *bit_obstack)
{
  if (!bit_obstack)
    {
      if (--bitmap_default_obstack_depth)
	{
	  gcc_assert (bitmap_default_obstack_depth > 0);
	  return;
	}
      bit_obstack = &bitmap_default_obstack;
    }

  bit_obstack->elements = NULL;
  bit_obstack->heads = NULL;
  obstack_free (&bit_obstack->obstack, NULL);
}

/* Create a new bitmap on an obstack.  If BIT_OBSTACK is NULL, create
   it on the default bitmap obstack.  */

bitmap
bitmap_alloc (bitmap_obstack *bit_obstack MEM_STAT_DECL)
{
  bitmap map;

  if (!bit_obstack)
    {
      gcc_assert (bitmap_default_obstack_depth > 0);
      bit_obstack = &bitmap_default_obstack;
    }
  map = bit_obstack->heads;
  if (map)
    bit_obstack->heads = (class bitmap_head *) map->first;
  else
    map = XOBNEW (&bit_obstack->obstack, bitmap_head);
  bitmap_initialize (map, bit_obstack PASS_MEM_STAT);

  if (GATHER_STATISTICS)
    register_overhead (map, sizeof (bitmap_head));

  return map;
}

/* Create a new GCd bitmap.  */

bitmap
bitmap_gc_alloc (ALONE_MEM_STAT_DECL)
{
  bitmap map;

  map = ggc_alloc<bitmap_head> ();
  bitmap_initialize (map, NULL PASS_MEM_STAT);

  if (GATHER_STATISTICS)
    register_overhead (map, sizeof (bitmap_head));

  return map;
}

/* Release an obstack allocated bitmap.  */

void
bitmap_obstack_free (bitmap map)
{
  if (map)
    {
      bitmap_clear (map);
      map->first = (bitmap_element *) map->obstack->heads;

      if (GATHER_STATISTICS)
	release_overhead (map, sizeof (bitmap_head), true);

      map->obstack->heads = map;
    }
}


/* Return nonzero if all bits in an element are zero.  */

static inline int
bitmap_element_zerop (const bitmap_element *element)
{
#if BITMAP_ELEMENT_WORDS == 2
  return (element->bits[0] | element->bits[1]) == 0;
#else
  unsigned i;

  for (i = 0; i < BITMAP_ELEMENT_WORDS; i++)
    if (element->bits[i] != 0)
      return 0;

  return 1;
#endif
}

/* Copy a bitmap to another bitmap.  */

void
bitmap_copy (bitmap to, const_bitmap from)
{
  const bitmap_element *from_ptr;
  bitmap_element *to_ptr = 0;

  gcc_checking_assert (!to->tree_form && !from->tree_form);

  bitmap_clear (to);

  /* Copy elements in forward direction one at a time.  */
  for (from_ptr = from->first; from_ptr; from_ptr = from_ptr->next)
    {
      bitmap_element *to_elt = bitmap_element_allocate (to);

      to_elt->indx = from_ptr->indx;
      memcpy (to_elt->bits, from_ptr->bits, sizeof (to_elt->bits));

      /* Here we have a special case of bitmap_list_link_element,
         for the case where we know the links are being entered
	 in sequence.  */
      if (to_ptr == 0)
	{
	  to->first = to->current = to_elt;
	  to->indx = from_ptr->indx;
	  to_elt->next = to_elt->prev = 0;
	}
      else
	{
	  to_elt->prev = to_ptr;
	  to_elt->next = 0;
	  to_ptr->next = to_elt;
	}

      to_ptr = to_elt;
    }
}

/* Move a bitmap to another bitmap.  */

void
bitmap_move (bitmap to, bitmap from)
{
  gcc_assert (to->obstack == from->obstack);

  bitmap_clear (to);

  size_t sz = 0;
  if (GATHER_STATISTICS)
    {
      for (bitmap_element *e = to->first; e; e = e->next)
	sz += sizeof (bitmap_element);
      register_overhead (to, sz);
    }

  *to = *from;

  if (GATHER_STATISTICS)
    release_overhead (from, sz, false);
}

/* Clear a single bit in a bitmap.  Return true if the bit changed.  */

bool
bitmap_clear_bit (bitmap head, int bit)
{
  unsigned int indx = bit / BITMAP_ELEMENT_ALL_BITS;
  bitmap_element *ptr;

  if (!head->tree_form)
    ptr = bitmap_list_find_element (head, indx);
  else
    ptr = bitmap_tree_find_element (head, indx);
  if (ptr != 0)
    {
      unsigned bit_num  = bit % BITMAP_WORD_BITS;
      unsigned word_num = bit / BITMAP_WORD_BITS % BITMAP_ELEMENT_WORDS;
      BITMAP_WORD bit_val = ((BITMAP_WORD) 1) << bit_num;
      bool res = (ptr->bits[word_num] & bit_val) != 0;
      if (res)
	{
	  ptr->bits[word_num] &= ~bit_val;
	  /* If we cleared the entire word, free up the element.  */
	  if (!ptr->bits[word_num]
	      && bitmap_element_zerop (ptr))
	    {
	      if (!head->tree_form)
		bitmap_list_unlink_element (head, ptr);
	      else
		bitmap_tree_unlink_element (head, ptr);
	    }
	}

      return res;
    }

  return false;
}

/* Set a single bit in a bitmap.  Return true if the bit changed.  */

bool
bitmap_set_bit (bitmap head, int bit)
{
  unsigned indx = bit / BITMAP_ELEMENT_ALL_BITS;
  bitmap_element *ptr;
  if (!head->tree_form)
    ptr = bitmap_list_find_element (head, indx);
  else
    ptr = bitmap_tree_find_element (head, indx);
  unsigned word_num = bit / BITMAP_WORD_BITS % BITMAP_ELEMENT_WORDS;
  unsigned bit_num  = bit % BITMAP_WORD_BITS;
  BITMAP_WORD bit_val = ((BITMAP_WORD) 1) << bit_num;

  if (ptr != 0)
    {
      bool res = (ptr->bits[word_num] & bit_val) == 0;
      if (res)
	ptr->bits[word_num] |= bit_val;
      return res;
    }

  ptr = bitmap_element_allocate (head);
  ptr->indx = bit / BITMAP_ELEMENT_ALL_BITS;
  ptr->bits[word_num] = bit_val;
  if (!head->tree_form)
    bitmap_list_link_element (head, ptr);
  else
    bitmap_tree_link_element (head, ptr);
  return true;
}

/* Return whether a bit is set within a bitmap.  */

bool
bitmap_bit_p (const_bitmap head, int bit)
{
  unsigned int indx = bit / BITMAP_ELEMENT_ALL_BITS;
  const bitmap_element *ptr;
  unsigned bit_num;
  unsigned word_num;

  if (!head->tree_form)
    ptr = bitmap_list_find_element (const_cast<bitmap> (head), indx);
  else
    ptr = bitmap_tree_find_element (const_cast<bitmap> (head), indx);
  if (ptr == 0)
    return 0;

  bit_num = bit % BITMAP_WORD_BITS;
  word_num = bit / BITMAP_WORD_BITS % BITMAP_ELEMENT_WORDS;

  return (ptr->bits[word_num] >> bit_num) & 1;
}

/* Set CHUNK_SIZE bits at a time in bitmap HEAD.
   Store CHUNK_VALUE starting at bits CHUNK * chunk_size.
   This is the set routine for viewing bitmap as a multi-bit sparse array.  */

void
bitmap_set_aligned_chunk (bitmap head, unsigned int chunk,
			  unsigned int chunk_size, BITMAP_WORD chunk_value)
{
  // Ensure chunk size is a power of 2 and fits in BITMAP_WORD.
  gcc_checking_assert (pow2p_hwi (chunk_size));
  gcc_checking_assert (chunk_size < (sizeof (BITMAP_WORD) * CHAR_BIT));

  // Ensure chunk_value is within range of chunk_size bits.
  BITMAP_WORD max_value = (1 << chunk_size) - 1;
  gcc_checking_assert (chunk_value <= max_value);

  unsigned bit = chunk * chunk_size;
  unsigned indx = bit / BITMAP_ELEMENT_ALL_BITS;
  bitmap_element *ptr;
  if (!head->tree_form)
    ptr = bitmap_list_find_element (head, indx);
  else
    ptr = bitmap_tree_find_element (head, indx);
  unsigned word_num = bit / BITMAP_WORD_BITS % BITMAP_ELEMENT_WORDS;
  unsigned bit_num  = bit % BITMAP_WORD_BITS;
  BITMAP_WORD bit_val = chunk_value << bit_num;
  BITMAP_WORD mask = ~(max_value << bit_num);

  if (ptr != 0)
    {
      ptr->bits[word_num] &= mask;
      ptr->bits[word_num] |= bit_val;
      return;
    }

  ptr = bitmap_element_allocate (head);
  ptr->indx = bit / BITMAP_ELEMENT_ALL_BITS;
  ptr->bits[word_num] = bit_val;
  if (!head->tree_form)
    bitmap_list_link_element (head, ptr);
  else
    bitmap_tree_link_element (head, ptr);
}

/* This is the get routine for viewing bitmap as a multi-bit sparse array.
   Return a set of CHUNK_SIZE consecutive bits from HEAD, starting at bit
   CHUNK * chunk_size.   */

BITMAP_WORD
bitmap_get_aligned_chunk (const_bitmap head, unsigned int chunk,
			  unsigned int chunk_size)
{
  // Ensure chunk size is a power of 2, fits in BITMAP_WORD and is in range.
  gcc_checking_assert (pow2p_hwi (chunk_size));
  gcc_checking_assert (chunk_size < (sizeof (BITMAP_WORD) * CHAR_BIT));

  BITMAP_WORD max_value = (1 << chunk_size) - 1;
  unsigned bit = chunk * chunk_size;
  unsigned int indx = bit / BITMAP_ELEMENT_ALL_BITS;
  const bitmap_element *ptr;
  unsigned bit_num;
  unsigned word_num;

  if (!head->tree_form)
    ptr = bitmap_list_find_element (const_cast<bitmap> (head), indx);
  else
    ptr = bitmap_tree_find_element (const_cast<bitmap> (head), indx);
  if (ptr == 0)
    return 0;

  bit_num = bit % BITMAP_WORD_BITS;
  word_num = bit / BITMAP_WORD_BITS % BITMAP_ELEMENT_WORDS;

  // Return 4 bits.
  return (ptr->bits[word_num] >> bit_num) & max_value;
}

#if GCC_VERSION < 3400
/* Table of number of set bits in a character, indexed by value of char.  */
static const unsigned char popcount_table[] =
{
    0,1,1,2,1,2,2,3,1,2,2,3,2,3,3,4,1,2,2,3,2,3,3,4,2,3,3,4,3,4,4,5,
    1,2,2,3,2,3,3,4,2,3,3,4,3,4,4,5,2,3,3,4,3,4,4,5,3,4,4,5,4,5,5,6,
    1,2,2,3,2,3,3,4,2,3,3,4,3,4,4,5,2,3,3,4,3,4,4,5,3,4,4,5,4,5,5,6,
    2,3,3,4,3,4,4,5,3,4,4,5,4,5,5,6,3,4,4,5,4,5,5,6,4,5,5,6,5,6,6,7,
    1,2,2,3,2,3,3,4,2,3,3,4,3,4,4,5,2,3,3,4,3,4,4,5,3,4,4,5,4,5,5,6,
    2,3,3,4,3,4,4,5,3,4,4,5,4,5,5,6,3,4,4,5,4,5,5,6,4,5,5,6,5,6,6,7,
    2,3,3,4,3,4,4,5,3,4,4,5,4,5,5,6,3,4,4,5,4,5,5,6,4,5,5,6,5,6,6,7,
    3,4,4,5,4,5,5,6,4,5,5,6,5,6,6,7,4,5,5,6,5,6,6,7,5,6,6,7,6,7,7,8,
};

static unsigned long
bitmap_popcount (BITMAP_WORD a)
{
  unsigned long ret = 0;
  unsigned i;

  /* Just do this the table way for now  */
  for (i = 0; i < BITMAP_WORD_BITS; i+= 8)
    ret += popcount_table[(a >> i) & 0xff];
  return ret;
}
#endif

/* Count and return the number of bits set in the bitmap word BITS.  */
static unsigned long
bitmap_count_bits_in_word (const BITMAP_WORD *bits)
{
  unsigned long count = 0;

  for (unsigned ix = 0; ix != BITMAP_ELEMENT_WORDS; ix++)
    {
#if GCC_VERSION >= 3400
      /* Note that popcountl matches BITMAP_WORD in type, so the actual size
	 of BITMAP_WORD is not material.  */
      count += __builtin_popcountl (bits[ix]);
#else
      count += bitmap_popcount (bits[ix]);
#endif
    }
  return count;
}

/* Count the number of bits set in the bitmap, and return it.  */

unsigned long
bitmap_count_bits (const_bitmap a)
{
  unsigned long count = 0;
  const bitmap_element *elt;

  gcc_checking_assert (!a->tree_form);
  for (elt = a->first; elt; elt = elt->next)
    count += bitmap_count_bits_in_word (elt->bits);

  return count;
}

/* Count the number of unique bits set in A and B and return it.  */

unsigned long
bitmap_count_unique_bits (const_bitmap a, const_bitmap b)
{
  unsigned long count = 0;
  const bitmap_element *elt_a, *elt_b;

  for (elt_a = a->first, elt_b = b->first; elt_a && elt_b; )
    {
      /* If we're at different indices, then count all the bits
	 in the lower element.  If we're at the same index, then
	 count the bits in the IOR of the two elements.  */
      if (elt_a->indx < elt_b->indx)
	{
	  count += bitmap_count_bits_in_word (elt_a->bits);
	  elt_a = elt_a->next;
	}
      else if (elt_b->indx < elt_a->indx)
	{
	  count += bitmap_count_bits_in_word (elt_b->bits);
	  elt_b = elt_b->next;
	}
      else
	{
	  BITMAP_WORD bits[BITMAP_ELEMENT_WORDS];
	  for (unsigned ix = 0; ix != BITMAP_ELEMENT_WORDS; ix++)
	    bits[ix] = elt_a->bits[ix] | elt_b->bits[ix];
	  count += bitmap_count_bits_in_word (bits);
	  elt_a = elt_a->next;
	  elt_b = elt_b->next;
	}
    }
  return count;
}

/* Return true if the bitmap has a single bit set.  Otherwise return
   false.  */

bool
bitmap_single_bit_set_p (const_bitmap a)
{
  unsigned long count = 0;
  const bitmap_element *elt;
  unsigned ix;

  if (bitmap_empty_p (a))
    return false;

  elt = a->first;

  /* As there are no completely empty bitmap elements, a second one
     means we have more than one bit set.  */
  if (elt->next != NULL
      && (!a->tree_form || elt->prev != NULL))
    return false;

  for (ix = 0; ix != BITMAP_ELEMENT_WORDS; ix++)
    {
#if GCC_VERSION >= 3400
      /* Note that popcountl matches BITMAP_WORD in type, so the actual size
	 of BITMAP_WORD is not material.  */
      count += __builtin_popcountl (elt->bits[ix]);
#else
      count += bitmap_popcount (elt->bits[ix]);
#endif
      if (count > 1)
	return false;
    }

  return count == 1;
}


/* Return the bit number of the first set bit in the bitmap.  The
   bitmap must be non-empty.  When CLEAR is true it clears the bit.  */

static unsigned
bitmap_first_set_bit_worker (bitmap a, bool clear)
{
  bitmap_element *elt = a->first;
  unsigned bit_no;
  BITMAP_WORD word;
  unsigned ix;

  gcc_checking_assert (elt);

  if (a->tree_form)
    while (elt->prev)
      elt = elt->prev;

  bit_no = elt->indx * BITMAP_ELEMENT_ALL_BITS;
  for (ix = 0; ix != BITMAP_ELEMENT_WORDS; ix++)
    {
      word = elt->bits[ix];
      if (word)
	goto found_bit;
    }
  gcc_unreachable ();
 found_bit:
  bit_no += ix * BITMAP_WORD_BITS;

#if GCC_VERSION >= 3004
  gcc_assert (sizeof (long) == sizeof (word));
  bit_no += __builtin_ctzl (word);
#else
  /* Binary search for the first set bit.  */
#if BITMAP_WORD_BITS > 64
#error "Fill out the table."
#endif
#if BITMAP_WORD_BITS > 32
  if (!(word & 0xffffffff))
    word >>= 32, bit_no += 32;
#endif
  if (!(word & 0xffff))
    word >>= 16, bit_no += 16;
  if (!(word & 0xff))
    word >>= 8, bit_no += 8;
  if (!(word & 0xf))
    word >>= 4, bit_no += 4;
  if (!(word & 0x3))
    word >>= 2, bit_no += 2;
  if (!(word & 0x1))
    word >>= 1, bit_no += 1;

 gcc_checking_assert (word & 1);
#endif

 if (clear)
   {
     elt->bits[ix] &= ~((BITMAP_WORD) 1 << (bit_no % BITMAP_WORD_BITS));
     /* If we cleared the entire word, free up the element.  */
     if (!elt->bits[ix]
	 && bitmap_element_zerop (elt))
       {
	 if (!a->tree_form)
	   bitmap_list_unlink_element (a, elt);
	 else
	   bitmap_tree_unlink_element (a, elt);
       }
   }

 return bit_no;
}

/* Return the bit number of the first set bit in the bitmap.  The
   bitmap must be non-empty.  */

unsigned
bitmap_first_set_bit (const_bitmap a)
{
  return bitmap_first_set_bit_worker (const_cast<bitmap> (a), false);
}

/* Return and clear the bit number of the first set bit in the bitmap.  The
   bitmap must be non-empty.  */

unsigned
bitmap_clear_first_set_bit (bitmap a)
{
  return bitmap_first_set_bit_worker (a, true);
}

/* Return the bit number of the first set bit in the bitmap.  The
   bitmap must be non-empty.  */

unsigned
bitmap_last_set_bit (const_bitmap a)
{
  const bitmap_element *elt;
  unsigned bit_no;
  BITMAP_WORD word;
  int ix;

  if (a->tree_form)
    elt = a->first;
  else
    elt = a->current ? a->current : a->first;
  gcc_checking_assert (elt);

  while (elt->next)
    elt = elt->next;

  bit_no = elt->indx * BITMAP_ELEMENT_ALL_BITS;
  for (ix = BITMAP_ELEMENT_WORDS - 1; ix >= 1; ix--)
    {
      word = elt->bits[ix];
      if (word)
	goto found_bit;
    }
  gcc_assert (elt->bits[ix] != 0);
 found_bit:
  bit_no += ix * BITMAP_WORD_BITS;
#if GCC_VERSION >= 3004
  gcc_assert (sizeof (long) == sizeof (word));
  bit_no += BITMAP_WORD_BITS - __builtin_clzl (word) - 1;
#else
  /* Hopefully this is a twos-complement host...  */
  BITMAP_WORD x = word;
  x |= (x >> 1);
  x |= (x >> 2);
  x |= (x >> 4);
  x |= (x >> 8);
  x |= (x >> 16);
#if BITMAP_WORD_BITS > 32
  x |= (x >> 32);
#endif
  bit_no += bitmap_popcount (x) - 1;
#endif

  return bit_no;
}


/* DST = A & B.  */

void
bitmap_and (bitmap dst, const_bitmap a, const_bitmap b)
{
  bitmap_element *dst_elt = dst->first;
  const bitmap_element *a_elt = a->first;
  const bitmap_element *b_elt = b->first;
  bitmap_element *dst_prev = NULL;

  gcc_checking_assert (!dst->tree_form && !a->tree_form && !b->tree_form);
  gcc_assert (dst != a && dst != b);

  if (a == b)
    {
      bitmap_copy (dst, a);
      return;
    }

  while (a_elt && b_elt)
    {
      if (a_elt->indx < b_elt->indx)
	a_elt = a_elt->next;
      else if (b_elt->indx < a_elt->indx)
	b_elt = b_elt->next;
      else
	{
	  /* Matching elts, generate A & B.  */
	  unsigned ix;
	  BITMAP_WORD ior = 0;

	  if (!dst_elt)
	    dst_elt = bitmap_list_insert_element_after (dst, dst_prev,
							a_elt->indx);
	  else
	    dst_elt->indx = a_elt->indx;
	  for (ix = 0; ix < BITMAP_ELEMENT_WORDS; ix++)
	    {
	      BITMAP_WORD r = a_elt->bits[ix] & b_elt->bits[ix];

	      dst_elt->bits[ix] = r;
	      ior |= r;
	    }
	  if (ior)
	    {
	      dst_prev = dst_elt;
	      dst_elt = dst_elt->next;
	    }
	  a_elt = a_elt->next;
	  b_elt = b_elt->next;
	}
    }
  /* Ensure that dst->current is valid.  */
  dst->current = dst->first;
  bitmap_elt_clear_from (dst, dst_elt);
  gcc_checking_assert (!dst->current == !dst->first);
  if (dst->current)
    dst->indx = dst->current->indx;
}

/* A &= B.  Return true if A changed.  */

bool
bitmap_and_into (bitmap a, const_bitmap b)
{
  bitmap_element *a_elt = a->first;
  const bitmap_element *b_elt = b->first;
  bitmap_element *next;
  bool changed = false;

  gcc_checking_assert (!a->tree_form && !b->tree_form);

  if (a == b)
    return false;

  while (a_elt && b_elt)
    {
      if (a_elt->indx < b_elt->indx)
	{
	  next = a_elt->next;
	  bitmap_list_unlink_element (a, a_elt);
	  a_elt = next;
	  changed = true;
	}
      else if (b_elt->indx < a_elt->indx)
	b_elt = b_elt->next;
      else
	{
	  /* Matching elts, generate A &= B.  */
	  unsigned ix;
	  BITMAP_WORD ior = 0;

	  for (ix = 0; ix < BITMAP_ELEMENT_WORDS; ix++)
	    {
	      BITMAP_WORD r = a_elt->bits[ix] & b_elt->bits[ix];
	      if (a_elt->bits[ix] != r)
		changed = true;
	      a_elt->bits[ix] = r;
	      ior |= r;
	    }
	  next = a_elt->next;
	  if (!ior)
	    bitmap_list_unlink_element (a, a_elt);
	  a_elt = next;
	  b_elt = b_elt->next;
	}
    }

  if (a_elt)
    {
      changed = true;
      bitmap_elt_clear_from (a, a_elt);
    }

  gcc_checking_assert (!a->current == !a->first
		       && (!a->current || a->indx == a->current->indx));

  return changed;
}


/* Insert an element equal to SRC_ELT after DST_PREV, overwriting DST_ELT
   if non-NULL.  CHANGED is true if the destination bitmap had already been
   changed; the new value of CHANGED is returned.  */

static inline bool
bitmap_elt_copy (bitmap dst, bitmap_element *dst_elt, bitmap_element *dst_prev,
		 const bitmap_element *src_elt, bool changed)
{
  if (!changed && dst_elt && dst_elt->indx == src_elt->indx)
    {
      unsigned ix;

      for (ix = 0; ix < BITMAP_ELEMENT_WORDS; ix++)
	if (src_elt->bits[ix] != dst_elt->bits[ix])
	  {
	    dst_elt->bits[ix] = src_elt->bits[ix];
	    changed = true;
	  }
    }
  else
    {
      changed = true;
      if (!dst_elt)
	dst_elt = bitmap_list_insert_element_after (dst, dst_prev,
						    src_elt->indx);
      else
	dst_elt->indx = src_elt->indx;
      memcpy (dst_elt->bits, src_elt->bits, sizeof (dst_elt->bits));
    }
  return changed;
}



/* DST = A & ~B  */

bool
bitmap_and_compl (bitmap dst, const_bitmap a, const_bitmap b)
{
  bitmap_element *dst_elt = dst->first;
  const bitmap_element *a_elt = a->first;
  const bitmap_element *b_elt = b->first;
  bitmap_element *dst_prev = NULL;
  bitmap_element **dst_prev_pnext = &dst->first;
  bool changed = false;

  gcc_checking_assert (!dst->tree_form && !a->tree_form && !b->tree_form);
  gcc_assert (dst != a && dst != b);

  if (a == b)
    {
      changed = !bitmap_empty_p (dst);
      bitmap_clear (dst);
      return changed;
    }

  while (a_elt)
    {
      while (b_elt && b_elt->indx < a_elt->indx)
	b_elt = b_elt->next;

      if (!b_elt || b_elt->indx > a_elt->indx)
	{
	  changed = bitmap_elt_copy (dst, dst_elt, dst_prev, a_elt, changed);
	  dst_prev = *dst_prev_pnext;
	  dst_prev_pnext = &dst_prev->next;
	  dst_elt = *dst_prev_pnext;
	  a_elt = a_elt->next;
	}

      else
	{
	  /* Matching elts, generate A & ~B.  */
	  unsigned ix;
	  BITMAP_WORD ior = 0;

	  if (!changed && dst_elt && dst_elt->indx == a_elt->indx)
	    {
	      for (ix = 0; ix < BITMAP_ELEMENT_WORDS; ix++)
		{
		  BITMAP_WORD r = a_elt->bits[ix] & ~b_elt->bits[ix];

		  if (dst_elt->bits[ix] != r)
		    {
		      changed = true;
		      dst_elt->bits[ix] = r;
		    }
		  ior |= r;
		}
	    }
	  else
	    {
	      bool new_element;
	      if (!dst_elt || dst_elt->indx > a_elt->indx)
		{
		  dst_elt = bitmap_list_insert_element_after (dst, dst_prev,
							      a_elt->indx);
		  new_element = true;
		}
	      else
		{
		  dst_elt->indx = a_elt->indx;
		  new_element = false;
		}

	      for (ix = 0; ix < BITMAP_ELEMENT_WORDS; ix++)
		{
		  BITMAP_WORD r = a_elt->bits[ix] & ~b_elt->bits[ix];

		  dst_elt->bits[ix] = r;
		  ior |= r;
		}

	      if (ior)
	        changed = true;
	      else
	        {
	          changed |= !new_element;
		  bitmap_list_unlink_element (dst, dst_elt);
		  dst_elt = *dst_prev_pnext;
		}
	    }

	  if (ior)
	    {
	      dst_prev = *dst_prev_pnext;
	      dst_prev_pnext = &dst_prev->next;
	      dst_elt = *dst_prev_pnext;
	    }
	  a_elt = a_elt->next;
	  b_elt = b_elt->next;
	}
    }

  /* Ensure that dst->current is valid.  */
  dst->current = dst->first;

  if (dst_elt)
    {
      changed = true;
      bitmap_elt_clear_from (dst, dst_elt);
    }
  gcc_checking_assert (!dst->current == !dst->first);
  if (dst->current)
    dst->indx = dst->current->indx;

  return changed;
}

/* A &= ~B. Returns true if A changes */

bool
bitmap_and_compl_into (bitmap a, const_bitmap b)
{
  bitmap_element *a_elt = a->first;
  const bitmap_element *b_elt = b->first;
  bitmap_element *next;
  BITMAP_WORD changed = 0;

  gcc_checking_assert (!a->tree_form && !b->tree_form);

  if (a == b)
    {
      if (bitmap_empty_p (a))
	return false;
      else
	{
	  bitmap_clear (a);
	  return true;
	}
    }

  while (a_elt && b_elt)
    {
      if (a_elt->indx < b_elt->indx)
	a_elt = a_elt->next;
      else if (b_elt->indx < a_elt->indx)
	b_elt = b_elt->next;
      else
	{
	  /* Matching elts, generate A &= ~B.  */
	  unsigned ix;
	  BITMAP_WORD ior = 0;

	  for (ix = 0; ix < BITMAP_ELEMENT_WORDS; ix++)
	    {
	      BITMAP_WORD cleared = a_elt->bits[ix] & b_elt->bits[ix];
	      BITMAP_WORD r = a_elt->bits[ix] ^ cleared;

	      a_elt->bits[ix] = r;
	      changed |= cleared;
	      ior |= r;
	    }
	  next = a_elt->next;
	  if (!ior)
	    bitmap_list_unlink_element (a, a_elt);
	  a_elt = next;
	  b_elt = b_elt->next;
	}
    }
  gcc_checking_assert (!a->current == !a->first
		       && (!a->current || a->indx == a->current->indx));
  return changed != 0;
}

/* Set COUNT bits from START in HEAD.  */
void
bitmap_set_range (bitmap head, unsigned int start, unsigned int count)
{
  unsigned int first_index, end_bit_plus1, last_index;
  bitmap_element *elt, *elt_prev;
  unsigned int i;

  gcc_checking_assert (!head->tree_form);

  if (!count)
    return;

  if (count == 1)
    {
      bitmap_set_bit (head, start);
      return;
    }

  first_index = start / BITMAP_ELEMENT_ALL_BITS;
  end_bit_plus1 = start + count;
  last_index = (end_bit_plus1 - 1) / BITMAP_ELEMENT_ALL_BITS;
  elt = bitmap_list_find_element (head, first_index);

  /* If bitmap_list_find_element returns zero, the current is the closest block
     to the result.  Otherwise, just use bitmap_element_allocate to
     ensure ELT is set; in the loop below, ELT == NULL means "insert
     at the end of the bitmap".  */
  if (!elt)
    {
      elt = bitmap_element_allocate (head);
      elt->indx = first_index;
      bitmap_list_link_element (head, elt);
    }

  gcc_checking_assert (elt->indx == first_index);
  elt_prev = elt->prev;
  for (i = first_index; i <= last_index; i++)
    {
      unsigned elt_start_bit = i * BITMAP_ELEMENT_ALL_BITS;
      unsigned elt_end_bit_plus1 = elt_start_bit + BITMAP_ELEMENT_ALL_BITS;

      unsigned int first_word_to_mod;
      BITMAP_WORD first_mask;
      unsigned int last_word_to_mod;
      BITMAP_WORD last_mask;
      unsigned int ix;

      if (!elt || elt->indx != i)
	elt = bitmap_list_insert_element_after (head, elt_prev, i);

      if (elt_start_bit <= start)
	{
	  /* The first bit to turn on is somewhere inside this
	     elt.  */
	  first_word_to_mod = (start - elt_start_bit) / BITMAP_WORD_BITS;

	  /* This mask should have 1s in all bits >= start position. */
	  first_mask =
	    (((BITMAP_WORD) 1) << ((start % BITMAP_WORD_BITS))) - 1;
	  first_mask = ~first_mask;
	}
      else
	{
	  /* The first bit to turn on is below this start of this elt.  */
	  first_word_to_mod = 0;
	  first_mask = ~(BITMAP_WORD) 0;
	}

      if (elt_end_bit_plus1 <= end_bit_plus1)
	{
	  /* The last bit to turn on is beyond this elt.  */
	  last_word_to_mod = BITMAP_ELEMENT_WORDS - 1;
	  last_mask = ~(BITMAP_WORD) 0;
	}
      else
	{
	  /* The last bit to turn on is inside to this elt.  */
	  last_word_to_mod =
	    (end_bit_plus1 - elt_start_bit) / BITMAP_WORD_BITS;

	  /* The last mask should have 1s below the end bit.  */
	  last_mask =
	    (((BITMAP_WORD) 1) << ((end_bit_plus1 % BITMAP_WORD_BITS))) - 1;
	}

      if (first_word_to_mod == last_word_to_mod)
	{
	  BITMAP_WORD mask = first_mask & last_mask;
	  elt->bits[first_word_to_mod] |= mask;
	}
      else
	{
	  elt->bits[first_word_to_mod] |= first_mask;
	  if (BITMAP_ELEMENT_WORDS > 2)
	    for (ix = first_word_to_mod + 1; ix < last_word_to_mod; ix++)
	      elt->bits[ix] = ~(BITMAP_WORD) 0;
	  elt->bits[last_word_to_mod] |= last_mask;
	}

      elt_prev = elt;
      elt = elt->next;
    }

  head->current = elt ? elt : elt_prev;
  head->indx = head->current->indx;
}

/* Clear COUNT bits from START in HEAD.  */
void
bitmap_clear_range (bitmap head, unsigned int start, unsigned int count)
{
  unsigned int first_index, end_bit_plus1, last_index;
  bitmap_element *elt;

  gcc_checking_assert (!head->tree_form);

  if (!count)
    return;

  if (count == 1)
    {
      bitmap_clear_bit (head, start);
      return;
    }

  first_index = start / BITMAP_ELEMENT_ALL_BITS;
  end_bit_plus1 = start + count;
  last_index = (end_bit_plus1 - 1) / BITMAP_ELEMENT_ALL_BITS;
  elt = bitmap_list_find_element (head, first_index);

  /* If bitmap_list_find_element returns zero, the current is the closest block
     to the result.  If the current is less than first index, find the
     next one.  Otherwise, just set elt to be current.  */
  if (!elt)
    {
      if (head->current)
	{
	  if (head->indx < first_index)
	    {
	      elt = head->current->next;
	      if (!elt)
		return;
	    }
	  else
	    elt = head->current;
	}
      else
	return;
    }

  while (elt && (elt->indx <= last_index))
    {
      bitmap_element * next_elt = elt->next;
      unsigned elt_start_bit = (elt->indx) * BITMAP_ELEMENT_ALL_BITS;
      unsigned elt_end_bit_plus1 = elt_start_bit + BITMAP_ELEMENT_ALL_BITS;


      if (elt_start_bit >= start && elt_end_bit_plus1 <= end_bit_plus1)
	/* Get rid of the entire elt and go to the next one.  */
	bitmap_list_unlink_element (head, elt);
      else
	{
	  /* Going to have to knock out some bits in this elt.  */
	  unsigned int first_word_to_mod;
	  BITMAP_WORD first_mask;
	  unsigned int last_word_to_mod;
	  BITMAP_WORD last_mask;
	  unsigned int i;
	  bool clear = true;

	  if (elt_start_bit <= start)
	    {
	      /* The first bit to turn off is somewhere inside this
		 elt.  */
	      first_word_to_mod = (start - elt_start_bit) / BITMAP_WORD_BITS;

	      /* This mask should have 1s in all bits >= start position. */
	      first_mask =
		(((BITMAP_WORD) 1) << ((start % BITMAP_WORD_BITS))) - 1;
	      first_mask = ~first_mask;
	    }
	  else
	    {
	      /* The first bit to turn off is below this start of this elt.  */
	      first_word_to_mod = 0;
	      first_mask = 0;
	      first_mask = ~first_mask;
	    }

	  if (elt_end_bit_plus1 <= end_bit_plus1)
	    {
	      /* The last bit to turn off is beyond this elt.  */
	      last_word_to_mod = BITMAP_ELEMENT_WORDS - 1;
	      last_mask = 0;
	      last_mask = ~last_mask;
	    }
	  else
	    {
	      /* The last bit to turn off is inside to this elt.  */
	      last_word_to_mod =
		(end_bit_plus1 - elt_start_bit) / BITMAP_WORD_BITS;

	      /* The last mask should have 1s below the end bit.  */
	      last_mask =
		(((BITMAP_WORD) 1) << (((end_bit_plus1) % BITMAP_WORD_BITS))) - 1;
	    }


	  if (first_word_to_mod == last_word_to_mod)
	    {
	      BITMAP_WORD mask = first_mask & last_mask;
	      elt->bits[first_word_to_mod] &= ~mask;
	    }
	  else
	    {
	      elt->bits[first_word_to_mod] &= ~first_mask;
	      if (BITMAP_ELEMENT_WORDS > 2)
	        for (i = first_word_to_mod + 1; i < last_word_to_mod; i++)
		  elt->bits[i] = 0;
	      elt->bits[last_word_to_mod] &= ~last_mask;
	    }
	  for (i = 0; i < BITMAP_ELEMENT_WORDS; i++)
	    if (elt->bits[i])
	      {
		clear = false;
		break;
	      }
	  /* Check to see if there are any bits left.  */
	  if (clear)
	    bitmap_list_unlink_element (head, elt);
	}
      elt = next_elt;
    }

  if (elt)
    {
      head->current = elt;
      head->indx = head->current->indx;
    }
}

/* A = ~A & B. */

void
bitmap_compl_and_into (bitmap a, const_bitmap b)
{
  bitmap_element *a_elt = a->first;
  const bitmap_element *b_elt = b->first;
  bitmap_element *a_prev = NULL;
  bitmap_element *next;

  gcc_checking_assert (!a->tree_form && !b->tree_form);
  gcc_assert (a != b);

  if (bitmap_empty_p (a))
    {
      bitmap_copy (a, b);
      return;
    }
  if (bitmap_empty_p (b))
    {
      bitmap_clear (a);
      return;
    }

  while (a_elt || b_elt)
    {
      if (!b_elt || (a_elt && a_elt->indx < b_elt->indx))
	{
	  /* A is before B.  Remove A */
	  next = a_elt->next;
	  a_prev = a_elt->prev;
	  bitmap_list_unlink_element (a, a_elt);
	  a_elt = next;
	}
      else if (!a_elt || b_elt->indx < a_elt->indx)
	{
	  /* B is before A.  Copy B. */
	  next = bitmap_list_insert_element_after (a, a_prev, b_elt->indx);
	  memcpy (next->bits, b_elt->bits, sizeof (next->bits));
	  a_prev = next;
	  b_elt = b_elt->next;
	}
      else
	{
	  /* Matching elts, generate A = ~A & B.  */
	  unsigned ix;
	  BITMAP_WORD ior = 0;

	  for (ix = 0; ix < BITMAP_ELEMENT_WORDS; ix++)
	    {
	      BITMAP_WORD cleared = a_elt->bits[ix] & b_elt->bits[ix];
	      BITMAP_WORD r = b_elt->bits[ix] ^ cleared;

	      a_elt->bits[ix] = r;
	      ior |= r;
	    }
	  next = a_elt->next;
	  if (!ior)
	    bitmap_list_unlink_element (a, a_elt);
	  else
	    a_prev = a_elt;
	  a_elt = next;
	  b_elt = b_elt->next;
	}
    }
  gcc_checking_assert (!a->current == !a->first
		       && (!a->current || a->indx == a->current->indx));
  return;
}


/* Insert an element corresponding to A_ELT | B_ELT after DST_PREV,
   overwriting DST_ELT if non-NULL.  CHANGED is true if the destination bitmap
   had already been changed; the new value of CHANGED is returned.  */

static inline bool
bitmap_elt_ior (bitmap dst, bitmap_element *dst_elt, bitmap_element *dst_prev,
		const bitmap_element *a_elt, const bitmap_element *b_elt,
		bool changed)
{
  gcc_assert (a_elt || b_elt);

  if (a_elt && b_elt && a_elt->indx == b_elt->indx)
    {
      /* Matching elts, generate A | B.  */
      unsigned ix;

      if (!changed && dst_elt && dst_elt->indx == a_elt->indx)
	{
	  for (ix = 0; ix < BITMAP_ELEMENT_WORDS; ix++)
	    {
	      BITMAP_WORD r = a_elt->bits[ix] | b_elt->bits[ix];
	      if (r != dst_elt->bits[ix])
		{
		  dst_elt->bits[ix] = r;
		  changed = true;
		}
	    }
	}
      else
	{
	  changed = true;
	  if (!dst_elt)
	    dst_elt = bitmap_list_insert_element_after (dst, dst_prev,
							a_elt->indx);
	  else
	    dst_elt->indx = a_elt->indx;
	  for (ix = 0; ix < BITMAP_ELEMENT_WORDS; ix++)
	    {
	      BITMAP_WORD r = a_elt->bits[ix] | b_elt->bits[ix];
	      dst_elt->bits[ix] = r;
	    }
	}
    }
  else
    {
      /* Copy a single element.  */
      const bitmap_element *src;

      if (!b_elt || (a_elt && a_elt->indx < b_elt->indx))
	src = a_elt;
      else
	src = b_elt;

      gcc_checking_assert (src);
      changed = bitmap_elt_copy (dst, dst_elt, dst_prev, src, changed);
    }
  return changed;
}


/* DST = A | B.  Return true if DST changes.  */

bool
bitmap_ior (bitmap dst, const_bitmap a, const_bitmap b)
{
  bitmap_element *dst_elt = dst->first;
  const bitmap_element *a_elt = a->first;
  const bitmap_element *b_elt = b->first;
  bitmap_element *dst_prev = NULL;
  bitmap_element **dst_prev_pnext = &dst->first;
  bool changed = false;

  gcc_checking_assert (!dst->tree_form && !a->tree_form && !b->tree_form);
  gcc_assert (dst != a && dst != b);

  while (a_elt || b_elt)
    {
      changed = bitmap_elt_ior (dst, dst_elt, dst_prev, a_elt, b_elt, changed);

      if (a_elt && b_elt && a_elt->indx == b_elt->indx)
	{
	  a_elt = a_elt->next;
	  b_elt = b_elt->next;
	}
      else
	{
	  if (a_elt && (!b_elt || a_elt->indx <= b_elt->indx))
            a_elt = a_elt->next;
          else if (b_elt && (!a_elt || b_elt->indx <= a_elt->indx))
            b_elt = b_elt->next;
	}

      dst_prev = *dst_prev_pnext;
      dst_prev_pnext = &dst_prev->next;
      dst_elt = *dst_prev_pnext;
    }

  if (dst_elt)
    {
      changed = true;
      /* Ensure that dst->current is valid.  */
      dst->current = dst->first;
      bitmap_elt_clear_from (dst, dst_elt);
    }
  gcc_checking_assert (!dst->current == !dst->first);
  if (dst->current)
    dst->indx = dst->current->indx;
  return changed;
}

/* A |= B.  Return true if A changes.  */

bool
bitmap_ior_into (bitmap a, const_bitmap b)
{
  bitmap_element *a_elt = a->first;
  const bitmap_element *b_elt = b->first;
  bitmap_element *a_prev = NULL;
  bitmap_element **a_prev_pnext = &a->first;
  bool changed = false;

  gcc_checking_assert (!a->tree_form && !b->tree_form);
  if (a == b)
    return false;

  while (b_elt)
    {
      /* If A lags behind B, just advance it.  */
      if (!a_elt || a_elt->indx == b_elt->indx)
	{
	  changed = bitmap_elt_ior (a, a_elt, a_prev, a_elt, b_elt, changed);
	  b_elt = b_elt->next;
	}
      else if (a_elt->indx > b_elt->indx)
	{
          changed = bitmap_elt_copy (a, NULL, a_prev, b_elt, changed);
	  b_elt = b_elt->next;
	}

      a_prev = *a_prev_pnext;
      a_prev_pnext = &a_prev->next;
      a_elt = *a_prev_pnext;
    }

  gcc_checking_assert (!a->current == !a->first);
  if (a->current)
    a->indx = a->current->indx;
  return changed;
}

/* A |= B.  Return true if A changes.  Free B (re-using its storage
   for the result).  */

bool
bitmap_ior_into_and_free (bitmap a, bitmap *b_)
{
  bitmap b = *b_;
  bitmap_element *a_elt = a->first;
  bitmap_element *b_elt = b->first;
  bitmap_element *a_prev = NULL;
  bitmap_element **a_prev_pnext = &a->first;
  bool changed = false;

  gcc_checking_assert (!a->tree_form && !b->tree_form);
  gcc_assert (a->obstack == b->obstack);
  if (a == b)
    return false;

  while (b_elt)
    {
      /* If A lags behind B, just advance it.  */
      if (!a_elt || a_elt->indx == b_elt->indx)
	{
	  changed = bitmap_elt_ior (a, a_elt, a_prev, a_elt, b_elt, changed);
	  b_elt = b_elt->next;
	}
      else if (a_elt->indx > b_elt->indx)
	{
	  bitmap_element *b_elt_next = b_elt->next;
	  bitmap_list_unlink_element (b, b_elt, false);
	  bitmap_list_insert_element_after (a, a_prev, b_elt->indx, b_elt);
	  b_elt = b_elt_next;
	}

      a_prev = *a_prev_pnext;
      a_prev_pnext = &a_prev->next;
      a_elt = *a_prev_pnext;
    }

  gcc_checking_assert (!a->current == !a->first);
  if (a->current)
    a->indx = a->current->indx;

  if (b->obstack)
    BITMAP_FREE (*b_);
  else
    bitmap_clear (b);
  return changed;
}

/* DST = A ^ B  */

void
bitmap_xor (bitmap dst, const_bitmap a, const_bitmap b)
{
  bitmap_element *dst_elt = dst->first;
  const bitmap_element *a_elt = a->first;
  const bitmap_element *b_elt = b->first;
  bitmap_element *dst_prev = NULL;

  gcc_checking_assert (!dst->tree_form && !a->tree_form && !b->tree_form);
  gcc_assert (dst != a && dst != b);

  if (a == b)
    {
      bitmap_clear (dst);
      return;
    }

  while (a_elt || b_elt)
    {
      if (a_elt && b_elt && a_elt->indx == b_elt->indx)
	{
	  /* Matching elts, generate A ^ B.  */
	  unsigned ix;
	  BITMAP_WORD ior = 0;

	  if (!dst_elt)
	    dst_elt = bitmap_list_insert_element_after (dst, dst_prev,
							a_elt->indx);
	  else
	    dst_elt->indx = a_elt->indx;
	  for (ix = 0; ix < BITMAP_ELEMENT_WORDS; ix++)
	    {
	      BITMAP_WORD r = a_elt->bits[ix] ^ b_elt->bits[ix];

	      ior |= r;
	      dst_elt->bits[ix] = r;
	    }
	  a_elt = a_elt->next;
	  b_elt = b_elt->next;
	  if (ior)
	    {
	      dst_prev = dst_elt;
	      dst_elt = dst_elt->next;
	    }
	}
      else
	{
	  /* Copy a single element.  */
	  const bitmap_element *src;

	  if (!b_elt || (a_elt && a_elt->indx < b_elt->indx))
	    {
	      src = a_elt;
	      a_elt = a_elt->next;
	    }
	  else
	    {
	      src = b_elt;
	      b_elt = b_elt->next;
	    }

	  if (!dst_elt)
	    dst_elt = bitmap_list_insert_element_after (dst, dst_prev,
							src->indx);
	  else
	    dst_elt->indx = src->indx;
	  memcpy (dst_elt->bits, src->bits, sizeof (dst_elt->bits));
	  dst_prev = dst_elt;
	  dst_elt = dst_elt->next;
	}
    }
  /* Ensure that dst->current is valid.  */
  dst->current = dst->first;
  bitmap_elt_clear_from (dst, dst_elt);
  gcc_checking_assert (!dst->current == !dst->first);
  if (dst->current)
    dst->indx = dst->current->indx;
}

/* A ^= B */

void
bitmap_xor_into (bitmap a, const_bitmap b)
{
  bitmap_element *a_elt = a->first;
  const bitmap_element *b_elt = b->first;
  bitmap_element *a_prev = NULL;

  gcc_checking_assert (!a->tree_form && !b->tree_form);

  if (a == b)
    {
      bitmap_clear (a);
      return;
    }

  while (b_elt)
    {
      if (!a_elt || b_elt->indx < a_elt->indx)
	{
	  /* Copy b_elt.  */
	  bitmap_element *dst = bitmap_list_insert_element_after (a, a_prev,
								  b_elt->indx);
	  memcpy (dst->bits, b_elt->bits, sizeof (dst->bits));
	  a_prev = dst;
	  b_elt = b_elt->next;
	}
      else if (a_elt->indx < b_elt->indx)
	{
	  a_prev = a_elt;
	  a_elt = a_elt->next;
	}
      else
	{
	  /* Matching elts, generate A ^= B.  */
	  unsigned ix;
	  BITMAP_WORD ior = 0;
	  bitmap_element *next = a_elt->next;

	  for (ix = 0; ix < BITMAP_ELEMENT_WORDS; ix++)
	    {
	      BITMAP_WORD r = a_elt->bits[ix] ^ b_elt->bits[ix];

	      ior |= r;
	      a_elt->bits[ix] = r;
	    }
	  b_elt = b_elt->next;
	  if (ior)
	    a_prev = a_elt;
	  else
	    bitmap_list_unlink_element (a, a_elt);
	  a_elt = next;
	}
    }
  gcc_checking_assert (!a->current == !a->first);
  if (a->current)
    a->indx = a->current->indx;
}

/* Return true if two bitmaps are identical.
   We do not bother with a check for pointer equality, as that never
   occurs in practice.  */

bool
bitmap_equal_p (const_bitmap a, const_bitmap b)
{
  const bitmap_element *a_elt;
  const bitmap_element *b_elt;
  unsigned ix;

  gcc_checking_assert (!a->tree_form && !b->tree_form);

  for (a_elt = a->first, b_elt = b->first;
       a_elt && b_elt;
       a_elt = a_elt->next, b_elt = b_elt->next)
    {
      if (a_elt->indx != b_elt->indx)
	return false;
      for (ix = 0; ix < BITMAP_ELEMENT_WORDS; ix++)
	if (a_elt->bits[ix] != b_elt->bits[ix])
	  return false;
    }
  return !a_elt && !b_elt;
}

/* Return true if A AND B is not empty.  */

bool
bitmap_intersect_p (const_bitmap a, const_bitmap b)
{
  const bitmap_element *a_elt;
  const bitmap_element *b_elt;
  unsigned ix;

  gcc_checking_assert (!a->tree_form && !b->tree_form);

  for (a_elt = a->first, b_elt = b->first;
       a_elt && b_elt;)
    {
      if (a_elt->indx < b_elt->indx)
	a_elt = a_elt->next;
      else if (b_elt->indx < a_elt->indx)
	b_elt = b_elt->next;
      else
	{
	  for (ix = 0; ix < BITMAP_ELEMENT_WORDS; ix++)
	    if (a_elt->bits[ix] & b_elt->bits[ix])
	      return true;
	  a_elt = a_elt->next;
	  b_elt = b_elt->next;
	}
    }
  return false;
}

/* Return true if A AND NOT B is not empty.  */

bool
bitmap_intersect_compl_p (const_bitmap a, const_bitmap b)
{
  const bitmap_element *a_elt;
  const bitmap_element *b_elt;
  unsigned ix;

  gcc_checking_assert (!a->tree_form && !b->tree_form);

  for (a_elt = a->first, b_elt = b->first;
       a_elt && b_elt;)
    {
      if (a_elt->indx < b_elt->indx)
	return true;
      else if (b_elt->indx < a_elt->indx)
	b_elt = b_elt->next;
      else
	{
	  for (ix = 0; ix < BITMAP_ELEMENT_WORDS; ix++)
	    if (a_elt->bits[ix] & ~b_elt->bits[ix])
	      return true;
	  a_elt = a_elt->next;
	  b_elt = b_elt->next;
	}
    }
  return a_elt != NULL;
}


/* DST = A | (FROM1 & ~FROM2).  Return true if DST changes.  */

bool
bitmap_ior_and_compl (bitmap dst, const_bitmap a, const_bitmap b, const_bitmap kill)
{
  bool changed = false;

  bitmap_element *dst_elt = dst->first;
  const bitmap_element *a_elt = a->first;
  const bitmap_element *b_elt = b->first;
  const bitmap_element *kill_elt = kill->first;
  bitmap_element *dst_prev = NULL;
  bitmap_element **dst_prev_pnext = &dst->first;

  gcc_checking_assert (!dst->tree_form && !a->tree_form && !b->tree_form
		       && !kill->tree_form);
  gcc_assert (dst != a && dst != b && dst != kill);

  /* Special cases.  We don't bother checking for bitmap_equal_p (b, kill).  */
  if (b == kill || bitmap_empty_p (b))
    {
      changed = !bitmap_equal_p (dst, a);
      if (changed)
	bitmap_copy (dst, a);
      return changed;
    }
  if (bitmap_empty_p (kill))
    return bitmap_ior (dst, a, b);
  if (bitmap_empty_p (a))
    return bitmap_and_compl (dst, b, kill);

  while (a_elt || b_elt)
    {
      bool new_element = false;

      if (b_elt)
	while (kill_elt && kill_elt->indx < b_elt->indx)
	  kill_elt = kill_elt->next;

      if (b_elt && kill_elt && kill_elt->indx == b_elt->indx
	  && (!a_elt || a_elt->indx >= b_elt->indx))
        {
	  bitmap_element tmp_elt;
	  unsigned ix;

	  BITMAP_WORD ior = 0;
	  tmp_elt.indx = b_elt->indx;
	  for (ix = 0; ix < BITMAP_ELEMENT_WORDS; ix++)
            {
              BITMAP_WORD r = b_elt->bits[ix] & ~kill_elt->bits[ix];
              ior |= r;
              tmp_elt.bits[ix] = r;
            }

	  if (ior)
	    {
	      changed = bitmap_elt_ior (dst, dst_elt, dst_prev,
				        a_elt, &tmp_elt, changed);
	      new_element = true;
	      if (a_elt && a_elt->indx == b_elt->indx)
                a_elt = a_elt->next;
	    }

	  b_elt = b_elt->next;
	  kill_elt = kill_elt->next;
	}
      else
	{
	  changed = bitmap_elt_ior (dst, dst_elt, dst_prev,
				    a_elt, b_elt, changed);
	  new_element = true;

          if (a_elt && b_elt && a_elt->indx == b_elt->indx)
	    {
	      a_elt = a_elt->next;
	      b_elt = b_elt->next;
	    }
          else
	    {
	      if (a_elt && (!b_elt || a_elt->indx <= b_elt->indx))
                a_elt = a_elt->next;
              else if (b_elt && (!a_elt || b_elt->indx <= a_elt->indx))
                b_elt = b_elt->next;
	    }
	}

      if (new_element)
	{
	  dst_prev = *dst_prev_pnext;
	  dst_prev_pnext = &dst_prev->next;
	  dst_elt = *dst_prev_pnext;
	}
    }

  if (dst_elt)
    {
      changed = true;
      /* Ensure that dst->current is valid.  */
      dst->current = dst->first;
      bitmap_elt_clear_from (dst, dst_elt);
    }
  gcc_checking_assert (!dst->current == !dst->first);
  if (dst->current)
    dst->indx = dst->current->indx;

  return changed;
}

/* A |= (B & ~C).  Return true if A changes.  */

bool
bitmap_ior_and_compl_into (bitmap a, const_bitmap b, const_bitmap c)
{
  bitmap_element *a_elt = a->first;
  const bitmap_element *b_elt = b->first;
  const bitmap_element *c_elt = c->first;
  bitmap_element and_elt;
  bitmap_element *a_prev = NULL;
  bitmap_element **a_prev_pnext = &a->first;
  bool changed = false;
  unsigned ix;

  gcc_checking_assert (!a->tree_form && !b->tree_form && !c->tree_form);

  if (a == b)
    return false;
  if (bitmap_empty_p (c))
    return bitmap_ior_into (a, b);
  else if (bitmap_empty_p (a))
    return bitmap_and_compl (a, b, c);

  and_elt.indx = -1;
  while (b_elt)
    {
      /* Advance C.  */
      while (c_elt && c_elt->indx < b_elt->indx)
	c_elt = c_elt->next;

      const bitmap_element *and_elt_ptr;
      if (c_elt && c_elt->indx == b_elt->indx)
	{
	  BITMAP_WORD overall = 0;
	  and_elt_ptr = &and_elt;
	  and_elt.indx = b_elt->indx;
	  for (ix = 0; ix < BITMAP_ELEMENT_WORDS; ix++)
	    {
	      and_elt.bits[ix] = b_elt->bits[ix] & ~c_elt->bits[ix];
	      overall |= and_elt.bits[ix];
	    }
	  if (!overall)
	    {
	      b_elt = b_elt->next;
	      continue;
	    }
	}
      else
	and_elt_ptr = b_elt;

      b_elt = b_elt->next;

      /* Now find a place to insert AND_ELT.  */
      do
	{
	  ix = a_elt ? a_elt->indx : and_elt_ptr->indx;
          if (ix == and_elt_ptr->indx)
	    changed = bitmap_elt_ior (a, a_elt, a_prev, a_elt,
				      and_elt_ptr, changed);
          else if (ix > and_elt_ptr->indx)
	    changed = bitmap_elt_copy (a, NULL, a_prev, and_elt_ptr, changed);

          a_prev = *a_prev_pnext;
          a_prev_pnext = &a_prev->next;
          a_elt = *a_prev_pnext;

          /* If A lagged behind B/C, we advanced it so loop once more.  */
	}
      while (ix < and_elt_ptr->indx);
    }

  gcc_checking_assert (!a->current == !a->first);
  if (a->current)
    a->indx = a->current->indx;
  return changed;
}

/* A |= (B & C).  Return true if A changes.  */

bool
bitmap_ior_and_into (bitmap a, const_bitmap b, const_bitmap c)
{
  bitmap_element *a_elt = a->first;
  const bitmap_element *b_elt = b->first;
  const bitmap_element *c_elt = c->first;
  bitmap_element and_elt;
  bitmap_element *a_prev = NULL;
  bitmap_element **a_prev_pnext = &a->first;
  bool changed = false;
  unsigned ix;

  gcc_checking_assert (!a->tree_form && !b->tree_form && !c->tree_form);

  if (b == c)
    return bitmap_ior_into (a, b);
  if (bitmap_empty_p (b) || bitmap_empty_p (c))
    return false;

  and_elt.indx = -1;
  while (b_elt && c_elt)
    {
      BITMAP_WORD overall;

      /* Find a common item of B and C.  */
      while (b_elt->indx != c_elt->indx)
	{
          if (b_elt->indx < c_elt->indx)
	    {
	      b_elt = b_elt->next;
	      if (!b_elt)
		goto done;
	    }
          else
	    {
	      c_elt = c_elt->next;
	      if (!c_elt)
		goto done;
	    }
	}

      overall = 0;
      and_elt.indx = b_elt->indx;
      for (ix = 0; ix < BITMAP_ELEMENT_WORDS; ix++)
	{
	  and_elt.bits[ix] = b_elt->bits[ix] & c_elt->bits[ix];
	  overall |= and_elt.bits[ix];
	}

      b_elt = b_elt->next;
      c_elt = c_elt->next;
      if (!overall)
	continue;

      /* Now find a place to insert AND_ELT.  */
      do
	{
	  ix = a_elt ? a_elt->indx : and_elt.indx;
          if (ix == and_elt.indx)
	    changed = bitmap_elt_ior (a, a_elt, a_prev, a_elt, &and_elt, changed);
          else if (ix > and_elt.indx)
	    changed = bitmap_elt_copy (a, NULL, a_prev, &and_elt, changed);

          a_prev = *a_prev_pnext;
          a_prev_pnext = &a_prev->next;
          a_elt = *a_prev_pnext;

          /* If A lagged behind B/C, we advanced it so loop once more.  */
	}
      while (ix < and_elt.indx);
    }

 done:
  gcc_checking_assert (!a->current == !a->first);
  if (a->current)
    a->indx = a->current->indx;
  return changed;
}

/* Compute hash of bitmap (for purposes of hashing).  */

hashval_t
bitmap_hash (const_bitmap head)
{
  const bitmap_element *ptr;
  BITMAP_WORD hash = 0;
  int ix;

  gcc_checking_assert (!head->tree_form);

  for (ptr = head->first; ptr; ptr = ptr->next)
    {
      hash ^= ptr->indx;
      for (ix = 0; ix != BITMAP_ELEMENT_WORDS; ix++)
	hash ^= ptr->bits[ix];
    }
  return iterative_hash (&hash, sizeof (hash), 0);
}


/* Function to obtain a vector of bitmap elements in bit order from
   HEAD in tree view.  */

static void
bitmap_tree_to_vec (vec<bitmap_element *> &elts, const_bitmap head)
{
  gcc_checking_assert (head->tree_form);
  auto_vec<bitmap_element *, 32> stack;
  bitmap_element *e = head->first;
  while (true)
    {
      while (e != NULL)
	{
	  stack.safe_push (e);
	  e = e->prev;
	}
      if (stack.is_empty ())
	break;

      e = stack.pop ();
      elts.safe_push (e);
      e = e->next;
    }
}

/* Debugging function to print out the contents of a bitmap element.  */

DEBUG_FUNCTION void
debug_bitmap_elt_file (FILE *file, const bitmap_element *ptr)
{
  unsigned int i, j, col = 26;

  fprintf (file, "\t" HOST_PTR_PRINTF " next = " HOST_PTR_PRINTF
	   " prev = " HOST_PTR_PRINTF " indx = %u\n\t\tbits = {",
	   (const void*) ptr, (const void*) ptr->next,
	   (const void*) ptr->prev, ptr->indx);

  for (i = 0; i < BITMAP_ELEMENT_WORDS; i++)
    for (j = 0; j < BITMAP_WORD_BITS; j++)
      if ((ptr->bits[i] >> j) & 1)
	{
	  if (col > 70)
	    {
	      fprintf (file, "\n\t\t\t");
	      col = 24;
	    }

	  fprintf (file, " %u", (ptr->indx * BITMAP_ELEMENT_ALL_BITS
				 + i * BITMAP_WORD_BITS + j));
	  col += 4;
	}

  fprintf (file, " }\n");
}

/* Debugging function to print out the contents of a bitmap.  */

DEBUG_FUNCTION void
debug_bitmap_file (FILE *file, const_bitmap head)
{
  const bitmap_element *ptr;

  fprintf (file, "\nfirst = " HOST_PTR_PRINTF
	   " current = " HOST_PTR_PRINTF " indx = %u\n",
	   (void *) head->first, (void *) head->current, head->indx);

  if (head->tree_form)
    {
      auto_vec<bitmap_element *, 32> elts;
      bitmap_tree_to_vec (elts, head);
      for (unsigned i = 0; i < elts.length (); ++i)
	debug_bitmap_elt_file (file, elts[i]);
    }
  else
    for (ptr = head->first; ptr; ptr = ptr->next)
      debug_bitmap_elt_file (file, ptr);
}

/* Function to be called from the debugger to print the contents
   of a bitmap.  */

DEBUG_FUNCTION void
debug_bitmap (const_bitmap head)
{
  debug_bitmap_file (stderr, head);
}

/* Function to print out the contents of a bitmap.  Unlike debug_bitmap_file,
   it does not print anything but the bits.  */

DEBUG_FUNCTION void
bitmap_print (FILE *file, const_bitmap head, const char *prefix,
	      const char *suffix)
{
  const char *comma = "";
  unsigned i;

  fputs (prefix, file);
  if (head->tree_form)
    {
      auto_vec<bitmap_element *, 32> elts;
      bitmap_tree_to_vec (elts, head);
      for (i = 0; i < elts.length (); ++i)
	for (unsigned ix = 0; ix != BITMAP_ELEMENT_WORDS; ++ix)
	  {
	    BITMAP_WORD word = elts[i]->bits[ix];
	    for (unsigned bit = 0; bit != BITMAP_WORD_BITS; ++bit)
	      if (word & ((BITMAP_WORD)1 << bit))
		{
		  fprintf (file, "%s%d", comma,
			   (bit + BITMAP_WORD_BITS * ix
			    + elts[i]->indx * BITMAP_ELEMENT_ALL_BITS));
		  comma = ", ";
		}
	  }
    }
  else
    {
      bitmap_iterator bi;
      EXECUTE_IF_SET_IN_BITMAP (head, 0, i, bi)
	{
	  fprintf (file, "%s%d", comma, i);
	  comma = ", ";
	}
    }
  fputs (suffix, file);
}

/* Output per-bitmap memory usage statistics.  */
void
dump_bitmap_statistics (void)
{
  if (!GATHER_STATISTICS)
    return;

  bitmap_mem_desc.dump (BITMAP_ORIGIN);
}

DEBUG_FUNCTION void
debug (const bitmap_head &ref)
{
  dump_bitmap (stderr, &ref);
}

DEBUG_FUNCTION void
debug (const bitmap_head *ptr)
{
  if (ptr)
    debug (*ptr);
  else
    fprintf (stderr, "<nil>\n");
}

DEBUG_FUNCTION void
debug (const auto_bitmap &ref)
{
  debug ((const bitmap_head &) ref);
}

DEBUG_FUNCTION void
debug (const auto_bitmap *ptr)
{
  debug ((const bitmap_head *) ptr);
}

void
bitmap_head::dump ()
{
  debug (this);
}

#if CHECKING_P

namespace selftest {

/* Selftests for bitmaps.  */

/* Freshly-created bitmaps ought to be empty.  */

static void
test_gc_alloc ()
{
  bitmap b = bitmap_gc_alloc ();
  ASSERT_TRUE (bitmap_empty_p (b));
}

/* Verify bitmap_set_range.  */

static void
test_set_range ()
{
  bitmap b = bitmap_gc_alloc ();
  ASSERT_TRUE (bitmap_empty_p (b));

  bitmap_set_range (b, 7, 5);
  ASSERT_FALSE (bitmap_empty_p (b));
  ASSERT_EQ (5, bitmap_count_bits (b));

  /* Verify bitmap_bit_p at the boundaries.  */
  ASSERT_FALSE (bitmap_bit_p (b, 6));
  ASSERT_TRUE (bitmap_bit_p (b, 7));
  ASSERT_TRUE (bitmap_bit_p (b, 11));
  ASSERT_FALSE (bitmap_bit_p (b, 12));
}

/* Verify splitting a range into two pieces using bitmap_clear_bit.  */

static void
test_clear_bit_in_middle ()
{
  bitmap b = bitmap_gc_alloc ();

  /* Set b to [100..200].  */
  bitmap_set_range (b, 100, 100);
  ASSERT_EQ (100, bitmap_count_bits (b));

  /* Clear a bit in the middle.  */
  bool changed = bitmap_clear_bit (b, 150);
  ASSERT_TRUE (changed);
  ASSERT_EQ (99, bitmap_count_bits (b));
  ASSERT_TRUE (bitmap_bit_p (b, 149));
  ASSERT_FALSE (bitmap_bit_p (b, 150));
  ASSERT_TRUE (bitmap_bit_p (b, 151));
}

/* Verify bitmap_copy.  */

static void
test_copying ()
{
  bitmap src = bitmap_gc_alloc ();
  bitmap_set_range (src, 40, 10);

  bitmap dst = bitmap_gc_alloc ();
  ASSERT_FALSE (bitmap_equal_p (src, dst));
  bitmap_copy (dst, src);
  ASSERT_TRUE (bitmap_equal_p (src, dst));

  /* Verify that we can make them unequal again...  */
  bitmap_set_range (src, 70, 5);
  ASSERT_FALSE (bitmap_equal_p (src, dst));

  /* ...and that changing src after the copy didn't affect
     the other: */
  ASSERT_FALSE (bitmap_bit_p (dst, 70));
}

/* Verify bitmap_single_bit_set_p.  */

static void
test_bitmap_single_bit_set_p ()
{
  bitmap b = bitmap_gc_alloc ();

  ASSERT_FALSE (bitmap_single_bit_set_p (b));

  bitmap_set_range (b, 42, 1);
  ASSERT_TRUE (bitmap_single_bit_set_p (b));
  ASSERT_EQ (42, bitmap_first_set_bit (b));

  bitmap_set_range (b, 1066, 1);
  ASSERT_FALSE (bitmap_single_bit_set_p (b));
  ASSERT_EQ (42, bitmap_first_set_bit (b));

  bitmap_clear_range (b, 0, 100);
  ASSERT_TRUE (bitmap_single_bit_set_p (b));
  ASSERT_EQ (1066, bitmap_first_set_bit (b));
}

/* Verify accessing aligned bit chunks works as expected.  */

static void
test_aligned_chunk (unsigned num_bits)
{
  bitmap b = bitmap_gc_alloc ();
  int limit = 2 ^ num_bits;

  int index = 3;
  for (int x = 0; x < limit; x++)
    {
      bitmap_set_aligned_chunk (b, index, num_bits, (BITMAP_WORD) x);
      ASSERT_TRUE ((int) bitmap_get_aligned_chunk (b, index, num_bits) == x);
      ASSERT_TRUE ((int) bitmap_get_aligned_chunk (b, index + 1,
						   num_bits) == 0);
      ASSERT_TRUE ((int) bitmap_get_aligned_chunk (b, index - 1,
						   num_bits) == 0);
      index += 3;
    }
  index = 3;
  for (int x = 0; x < limit ; x++)
    {
      ASSERT_TRUE ((int) bitmap_get_aligned_chunk (b, index, num_bits) == x);
      index += 3;
    }
}

/* Run all of the selftests within this file.  */

void
bitmap_cc_tests ()
{
  test_gc_alloc ();
  test_set_range ();
  test_clear_bit_in_middle ();
  test_copying ();
  test_bitmap_single_bit_set_p ();
  /* Test 2, 4 and 8 bit aligned chunks.  */
  test_aligned_chunk (2);
  test_aligned_chunk (4);
  test_aligned_chunk (8);
}

} // namespace selftest
#endif /* CHECKING_P */

#include "gt-bitmap.h"