summaryrefslogtreecommitdiffstats
path: root/contrib/gcc/var-tracking.c
blob: c392b2ed7997d882264596a0bca8d6c5e3c43053 (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
3032
3033
3034
3035
/* Variable tracking routines for the GNU compiler.
   Copyright (C) 2002, 2003, 2004, 2005 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 2, 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 COPYING.  If not, write to the Free
   Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
   02110-1301, USA.  */

/* This file contains the variable tracking pass.  It computes where
   variables are located (which registers or where in memory) at each position
   in instruction stream and emits notes describing the locations.
   Debug information (DWARF2 location lists) is finally generated from
   these notes.
   With this debug information, it is possible to show variables
   even when debugging optimized code.

   How does the variable tracking pass work?

   First, it scans RTL code for uses, stores and clobbers (register/memory
   references in instructions), for call insns and for stack adjustments
   separately for each basic block and saves them to an array of micro
   operations.
   The micro operations of one instruction are ordered so that
   pre-modifying stack adjustment < use < use with no var < call insn <
     < set < clobber < post-modifying stack adjustment

   Then, a forward dataflow analysis is performed to find out how locations
   of variables change through code and to propagate the variable locations
   along control flow graph.
   The IN set for basic block BB is computed as a union of OUT sets of BB's
   predecessors, the OUT set for BB is copied from the IN set for BB and
   is changed according to micro operations in BB.

   The IN and OUT sets for basic blocks consist of a current stack adjustment
   (used for adjusting offset of variables addressed using stack pointer),
   the table of structures describing the locations of parts of a variable
   and for each physical register a linked list for each physical register.
   The linked list is a list of variable parts stored in the register,
   i.e. it is a list of triplets (reg, decl, offset) where decl is
   REG_EXPR (reg) and offset is REG_OFFSET (reg).  The linked list is used for
   effective deleting appropriate variable parts when we set or clobber the
   register.

   There may be more than one variable part in a register.  The linked lists
   should be pretty short so it is a good data structure here.
   For example in the following code, register allocator may assign same
   register to variables A and B, and both of them are stored in the same
   register in CODE:

     if (cond)
       set A;
     else
       set B;
     CODE;
     if (cond)
       use A;
     else
       use B;

   Finally, the NOTE_INSN_VAR_LOCATION notes describing the variable locations
   are emitted to appropriate positions in RTL code.  Each such a note describes
   the location of one variable at the point in instruction stream where the
   note is.  There is no need to emit a note for each variable before each
   instruction, we only emit these notes where the location of variable changes
   (this means that we also emit notes for changes between the OUT set of the
   previous block and the IN set of the current block).

   The notes consist of two parts:
   1. the declaration (from REG_EXPR or MEM_EXPR)
   2. the location of a variable - it is either a simple register/memory
      reference (for simple variables, for example int),
      or a parallel of register/memory references (for a large variables
      which consist of several parts, for example long long).

*/

#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"
#include "rtl.h"
#include "tree.h"
#include "hard-reg-set.h"
#include "basic-block.h"
#include "flags.h"
#include "output.h"
#include "insn-config.h"
#include "reload.h"
#include "sbitmap.h"
#include "alloc-pool.h"
#include "fibheap.h"
#include "hashtab.h"
#include "regs.h"
#include "expr.h"
#include "timevar.h"
#include "tree-pass.h"

/* Type of micro operation.  */
enum micro_operation_type
{
  MO_USE,	/* Use location (REG or MEM).  */
  MO_USE_NO_VAR,/* Use location which is not associated with a variable
		   or the variable is not trackable.  */
  MO_SET,	/* Set location.  */
  MO_COPY,	/* Copy the same portion of a variable from one
		   location to another.  */
  MO_CLOBBER,	/* Clobber location.  */
  MO_CALL,	/* Call insn.  */
  MO_ADJUST	/* Adjust stack pointer.  */
};

/* Where shall the note be emitted?  BEFORE or AFTER the instruction.  */
enum emit_note_where
{
  EMIT_NOTE_BEFORE_INSN,
  EMIT_NOTE_AFTER_INSN
};

/* Structure holding information about micro operation.  */
typedef struct micro_operation_def
{
  /* Type of micro operation.  */
  enum micro_operation_type type;

  union {
    /* Location.  */
    rtx loc;

    /* Stack adjustment.  */
    HOST_WIDE_INT adjust;
  } u;

  /* The instruction which the micro operation is in, for MO_USE,
     MO_USE_NO_VAR, MO_CALL and MO_ADJUST, or the subsequent
     instruction or note in the original flow (before any var-tracking
     notes are inserted, to simplify emission of notes), for MO_SET
     and MO_CLOBBER.  */
  rtx insn;
} micro_operation;

/* Structure for passing some other parameters to function
   emit_note_insn_var_location.  */
typedef struct emit_note_data_def
{
  /* The instruction which the note will be emitted before/after.  */
  rtx insn;

  /* Where the note will be emitted (before/after insn)?  */
  enum emit_note_where where;
} emit_note_data;

/* Description of location of a part of a variable.  The content of a physical
   register is described by a chain of these structures.
   The chains are pretty short (usually 1 or 2 elements) and thus
   chain is the best data structure.  */
typedef struct attrs_def
{
  /* Pointer to next member of the list.  */
  struct attrs_def *next;

  /* The rtx of register.  */
  rtx loc;

  /* The declaration corresponding to LOC.  */
  tree decl;

  /* Offset from start of DECL.  */
  HOST_WIDE_INT offset;
} *attrs;

/* Structure holding the IN or OUT set for a basic block.  */
typedef struct dataflow_set_def
{
  /* Adjustment of stack offset.  */
  HOST_WIDE_INT stack_adjust;

  /* Attributes for registers (lists of attrs).  */
  attrs regs[FIRST_PSEUDO_REGISTER];

  /* Variable locations.  */
  htab_t vars;
} dataflow_set;

/* The structure (one for each basic block) containing the information
   needed for variable tracking.  */
typedef struct variable_tracking_info_def
{
  /* Number of micro operations stored in the MOS array.  */
  int n_mos;

  /* The array of micro operations.  */
  micro_operation *mos;

  /* The IN and OUT set for dataflow analysis.  */
  dataflow_set in;
  dataflow_set out;

  /* Has the block been visited in DFS?  */
  bool visited;
} *variable_tracking_info;

/* Structure for chaining the locations.  */
typedef struct location_chain_def
{
  /* Next element in the chain.  */
  struct location_chain_def *next;

  /* The location (REG or MEM).  */
  rtx loc;
} *location_chain;

/* Structure describing one part of variable.  */
typedef struct variable_part_def
{
  /* Chain of locations of the part.  */
  location_chain loc_chain;

  /* Location which was last emitted to location list.  */
  rtx cur_loc;

  /* The offset in the variable.  */
  HOST_WIDE_INT offset;
} variable_part;

/* Maximum number of location parts.  */
#define MAX_VAR_PARTS 16

/* Structure describing where the variable is located.  */
typedef struct variable_def
{
  /* The declaration of the variable.  */
  tree decl;

  /* Reference count.  */
  int refcount;

  /* Number of variable parts.  */
  int n_var_parts;

  /* The variable parts.  */
  variable_part var_part[MAX_VAR_PARTS];
} *variable;

/* Hash function for DECL for VARIABLE_HTAB.  */
#define VARIABLE_HASH_VAL(decl) (DECL_UID (decl))

/* Pointer to the BB's information specific to variable tracking pass.  */
#define VTI(BB) ((variable_tracking_info) (BB)->aux)

/* Macro to access MEM_OFFSET as an HOST_WIDE_INT.  Evaluates MEM twice.  */
#define INT_MEM_OFFSET(mem) (MEM_OFFSET (mem) ? INTVAL (MEM_OFFSET (mem)) : 0)

/* Alloc pool for struct attrs_def.  */
static alloc_pool attrs_pool;

/* Alloc pool for struct variable_def.  */
static alloc_pool var_pool;

/* Alloc pool for struct location_chain_def.  */
static alloc_pool loc_chain_pool;

/* Changed variables, notes will be emitted for them.  */
static htab_t changed_variables;

/* Shall notes be emitted?  */
static bool emit_notes;

/* Local function prototypes.  */
static void stack_adjust_offset_pre_post (rtx, HOST_WIDE_INT *,
					  HOST_WIDE_INT *);
static void insn_stack_adjust_offset_pre_post (rtx, HOST_WIDE_INT *,
					       HOST_WIDE_INT *);
static void bb_stack_adjust_offset (basic_block);
static bool vt_stack_adjustments (void);
static rtx adjust_stack_reference (rtx, HOST_WIDE_INT);
static hashval_t variable_htab_hash (const void *);
static int variable_htab_eq (const void *, const void *);
static void variable_htab_free (void *);

static void init_attrs_list_set (attrs *);
static void attrs_list_clear (attrs *);
static attrs attrs_list_member (attrs, tree, HOST_WIDE_INT);
static void attrs_list_insert (attrs *, tree, HOST_WIDE_INT, rtx);
static void attrs_list_copy (attrs *, attrs);
static void attrs_list_union (attrs *, attrs);

static void vars_clear (htab_t);
static variable unshare_variable (dataflow_set *set, variable var);
static int vars_copy_1 (void **, void *);
static void vars_copy (htab_t, htab_t);
static tree var_debug_decl (tree);
static void var_reg_set (dataflow_set *, rtx);
static void var_reg_delete_and_set (dataflow_set *, rtx, bool);
static void var_reg_delete (dataflow_set *, rtx, bool);
static void var_regno_delete (dataflow_set *, int);
static void var_mem_set (dataflow_set *, rtx);
static void var_mem_delete_and_set (dataflow_set *, rtx, bool);
static void var_mem_delete (dataflow_set *, rtx, bool);

static void dataflow_set_init (dataflow_set *, int);
static void dataflow_set_clear (dataflow_set *);
static void dataflow_set_copy (dataflow_set *, dataflow_set *);
static int variable_union_info_cmp_pos (const void *, const void *);
static int variable_union (void **, void *);
static void dataflow_set_union (dataflow_set *, dataflow_set *);
static bool variable_part_different_p (variable_part *, variable_part *);
static bool variable_different_p (variable, variable, bool);
static int dataflow_set_different_1 (void **, void *);
static int dataflow_set_different_2 (void **, void *);
static bool dataflow_set_different (dataflow_set *, dataflow_set *);
static void dataflow_set_destroy (dataflow_set *);

static bool contains_symbol_ref (rtx);
static bool track_expr_p (tree);
static bool same_variable_part_p (rtx, tree, HOST_WIDE_INT);
static int count_uses (rtx *, void *);
static void count_uses_1 (rtx *, void *);
static void count_stores (rtx, rtx, void *);
static int add_uses (rtx *, void *);
static void add_uses_1 (rtx *, void *);
static void add_stores (rtx, rtx, void *);
static bool compute_bb_dataflow (basic_block);
static void vt_find_locations (void);

static void dump_attrs_list (attrs);
static int dump_variable (void **, void *);
static void dump_vars (htab_t);
static void dump_dataflow_set (dataflow_set *);
static void dump_dataflow_sets (void);

static void variable_was_changed (variable, htab_t);
static void set_variable_part (dataflow_set *, rtx, tree, HOST_WIDE_INT);
static void clobber_variable_part (dataflow_set *, rtx, tree, HOST_WIDE_INT);
static void delete_variable_part (dataflow_set *, rtx, tree, HOST_WIDE_INT);
static int emit_note_insn_var_location (void **, void *);
static void emit_notes_for_changes (rtx, enum emit_note_where);
static int emit_notes_for_differences_1 (void **, void *);
static int emit_notes_for_differences_2 (void **, void *);
static void emit_notes_for_differences (rtx, dataflow_set *, dataflow_set *);
static void emit_notes_in_bb (basic_block);
static void vt_emit_notes (void);

static bool vt_get_decl_and_offset (rtx, tree *, HOST_WIDE_INT *);
static void vt_add_function_parameters (void);
static void vt_initialize (void);
static void vt_finalize (void);

/* Given a SET, calculate the amount of stack adjustment it contains
   PRE- and POST-modifying stack pointer.
   This function is similar to stack_adjust_offset.  */

static void
stack_adjust_offset_pre_post (rtx pattern, HOST_WIDE_INT *pre,
			      HOST_WIDE_INT *post)
{
  rtx src = SET_SRC (pattern);
  rtx dest = SET_DEST (pattern);
  enum rtx_code code;

  if (dest == stack_pointer_rtx)
    {
      /* (set (reg sp) (plus (reg sp) (const_int))) */
      code = GET_CODE (src);
      if (! (code == PLUS || code == MINUS)
	  || XEXP (src, 0) != stack_pointer_rtx
	  || GET_CODE (XEXP (src, 1)) != CONST_INT)
	return;

      if (code == MINUS)
	*post += INTVAL (XEXP (src, 1));
      else
	*post -= INTVAL (XEXP (src, 1));
    }
  else if (MEM_P (dest))
    {
      /* (set (mem (pre_dec (reg sp))) (foo)) */
      src = XEXP (dest, 0);
      code = GET_CODE (src);

      switch (code)
	{
	case PRE_MODIFY:
	case POST_MODIFY:
	  if (XEXP (src, 0) == stack_pointer_rtx)
	    {
	      rtx val = XEXP (XEXP (src, 1), 1);
	      /* We handle only adjustments by constant amount.  */
	      gcc_assert (GET_CODE (XEXP (src, 1)) == PLUS &&
			  GET_CODE (val) == CONST_INT);
	      
	      if (code == PRE_MODIFY)
		*pre -= INTVAL (val);
	      else
		*post -= INTVAL (val);
	      break;
	    }
	  return;

	case PRE_DEC:
	  if (XEXP (src, 0) == stack_pointer_rtx)
	    {
	      *pre += GET_MODE_SIZE (GET_MODE (dest));
	      break;
	    }
	  return;

	case POST_DEC:
	  if (XEXP (src, 0) == stack_pointer_rtx)
	    {
	      *post += GET_MODE_SIZE (GET_MODE (dest));
	      break;
	    }
	  return;

	case PRE_INC:
	  if (XEXP (src, 0) == stack_pointer_rtx)
	    {
	      *pre -= GET_MODE_SIZE (GET_MODE (dest));
	      break;
	    }
	  return;

	case POST_INC:
	  if (XEXP (src, 0) == stack_pointer_rtx)
	    {
	      *post -= GET_MODE_SIZE (GET_MODE (dest));
	      break;
	    }
	  return;

	default:
	  return;
	}
    }
}

/* Given an INSN, calculate the amount of stack adjustment it contains
   PRE- and POST-modifying stack pointer.  */

static void
insn_stack_adjust_offset_pre_post (rtx insn, HOST_WIDE_INT *pre,
				   HOST_WIDE_INT *post)
{
  *pre = 0;
  *post = 0;

  if (GET_CODE (PATTERN (insn)) == SET)
    stack_adjust_offset_pre_post (PATTERN (insn), pre, post);
  else if (GET_CODE (PATTERN (insn)) == PARALLEL
	   || GET_CODE (PATTERN (insn)) == SEQUENCE)
    {
      int i;

      /* There may be stack adjustments inside compound insns.  Search
	 for them.  */
      for ( i = XVECLEN (PATTERN (insn), 0) - 1; i >= 0; i--)
	if (GET_CODE (XVECEXP (PATTERN (insn), 0, i)) == SET)
	  stack_adjust_offset_pre_post (XVECEXP (PATTERN (insn), 0, i),
					pre, post);
    }
}

/* Compute stack adjustment in basic block BB.  */

static void
bb_stack_adjust_offset (basic_block bb)
{
  HOST_WIDE_INT offset;
  int i;

  offset = VTI (bb)->in.stack_adjust;
  for (i = 0; i < VTI (bb)->n_mos; i++)
    {
      if (VTI (bb)->mos[i].type == MO_ADJUST)
	offset += VTI (bb)->mos[i].u.adjust;
      else if (VTI (bb)->mos[i].type != MO_CALL)
	{
	  if (MEM_P (VTI (bb)->mos[i].u.loc))
	    {
	      VTI (bb)->mos[i].u.loc
		= adjust_stack_reference (VTI (bb)->mos[i].u.loc, -offset);
	    }
	}
    }
  VTI (bb)->out.stack_adjust = offset;
}

/* Compute stack adjustments for all blocks by traversing DFS tree.
   Return true when the adjustments on all incoming edges are consistent.
   Heavily borrowed from pre_and_rev_post_order_compute.  */

static bool
vt_stack_adjustments (void)
{
  edge_iterator *stack;
  int sp;

  /* Initialize entry block.  */
  VTI (ENTRY_BLOCK_PTR)->visited = true;
  VTI (ENTRY_BLOCK_PTR)->out.stack_adjust = INCOMING_FRAME_SP_OFFSET;

  /* Allocate stack for back-tracking up CFG.  */
  stack = XNEWVEC (edge_iterator, n_basic_blocks + 1);
  sp = 0;

  /* Push the first edge on to the stack.  */
  stack[sp++] = ei_start (ENTRY_BLOCK_PTR->succs);

  while (sp)
    {
      edge_iterator ei;
      basic_block src;
      basic_block dest;

      /* Look at the edge on the top of the stack.  */
      ei = stack[sp - 1];
      src = ei_edge (ei)->src;
      dest = ei_edge (ei)->dest;

      /* Check if the edge destination has been visited yet.  */
      if (!VTI (dest)->visited)
	{
	  VTI (dest)->visited = true;
	  VTI (dest)->in.stack_adjust = VTI (src)->out.stack_adjust;
	  bb_stack_adjust_offset (dest);

	  if (EDGE_COUNT (dest->succs) > 0)
	    /* Since the DEST node has been visited for the first
	       time, check its successors.  */
	    stack[sp++] = ei_start (dest->succs);
	}
      else
	{
	  /* Check whether the adjustments on the edges are the same.  */
	  if (VTI (dest)->in.stack_adjust != VTI (src)->out.stack_adjust)
	    {
	      free (stack);
	      return false;
	    }

	  if (! ei_one_before_end_p (ei))
	    /* Go to the next edge.  */
	    ei_next (&stack[sp - 1]);
	  else
	    /* Return to previous level if there are no more edges.  */
	    sp--;
	}
    }

  free (stack);
  return true;
}

/* Adjust stack reference MEM by ADJUSTMENT bytes and make it relative
   to the argument pointer.  Return the new rtx.  */

static rtx
adjust_stack_reference (rtx mem, HOST_WIDE_INT adjustment)
{
  rtx addr, cfa, tmp;

#ifdef FRAME_POINTER_CFA_OFFSET
  adjustment -= FRAME_POINTER_CFA_OFFSET (current_function_decl);
  cfa = plus_constant (frame_pointer_rtx, adjustment);
#else
  adjustment -= ARG_POINTER_CFA_OFFSET (current_function_decl);
  cfa = plus_constant (arg_pointer_rtx, adjustment);
#endif

  addr = replace_rtx (copy_rtx (XEXP (mem, 0)), stack_pointer_rtx, cfa);
  tmp = simplify_rtx (addr);
  if (tmp)
    addr = tmp;

  return replace_equiv_address_nv (mem, addr);
}

/* The hash function for variable_htab, computes the hash value
   from the declaration of variable X.  */

static hashval_t
variable_htab_hash (const void *x)
{
  const variable v = (const variable) x;

  return (VARIABLE_HASH_VAL (v->decl));
}

/* Compare the declaration of variable X with declaration Y.  */

static int
variable_htab_eq (const void *x, const void *y)
{
  const variable v = (const variable) x;
  const tree decl = (const tree) y;

  return (VARIABLE_HASH_VAL (v->decl) == VARIABLE_HASH_VAL (decl));
}

/* Free the element of VARIABLE_HTAB (its type is struct variable_def).  */

static void
variable_htab_free (void *elem)
{
  int i;
  variable var = (variable) elem;
  location_chain node, next;

  gcc_assert (var->refcount > 0);

  var->refcount--;
  if (var->refcount > 0)
    return;

  for (i = 0; i < var->n_var_parts; i++)
    {
      for (node = var->var_part[i].loc_chain; node; node = next)
	{
	  next = node->next;
	  pool_free (loc_chain_pool, node);
	}
      var->var_part[i].loc_chain = NULL;
    }
  pool_free (var_pool, var);
}

/* Initialize the set (array) SET of attrs to empty lists.  */

static void
init_attrs_list_set (attrs *set)
{
  int i;

  for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
    set[i] = NULL;
}

/* Make the list *LISTP empty.  */

static void
attrs_list_clear (attrs *listp)
{
  attrs list, next;

  for (list = *listp; list; list = next)
    {
      next = list->next;
      pool_free (attrs_pool, list);
    }
  *listp = NULL;
}

/* Return true if the pair of DECL and OFFSET is the member of the LIST.  */

static attrs
attrs_list_member (attrs list, tree decl, HOST_WIDE_INT offset)
{
  for (; list; list = list->next)
    if (list->decl == decl && list->offset == offset)
      return list;
  return NULL;
}

/* Insert the triplet DECL, OFFSET, LOC to the list *LISTP.  */

static void
attrs_list_insert (attrs *listp, tree decl, HOST_WIDE_INT offset, rtx loc)
{
  attrs list;

  list = pool_alloc (attrs_pool);
  list->loc = loc;
  list->decl = decl;
  list->offset = offset;
  list->next = *listp;
  *listp = list;
}

/* Copy all nodes from SRC and create a list *DSTP of the copies.  */

static void
attrs_list_copy (attrs *dstp, attrs src)
{
  attrs n;

  attrs_list_clear (dstp);
  for (; src; src = src->next)
    {
      n = pool_alloc (attrs_pool);
      n->loc = src->loc;
      n->decl = src->decl;
      n->offset = src->offset;
      n->next = *dstp;
      *dstp = n;
    }
}

/* Add all nodes from SRC which are not in *DSTP to *DSTP.  */

static void
attrs_list_union (attrs *dstp, attrs src)
{
  for (; src; src = src->next)
    {
      if (!attrs_list_member (*dstp, src->decl, src->offset))
	attrs_list_insert (dstp, src->decl, src->offset, src->loc);
    }
}

/* Delete all variables from hash table VARS.  */

static void
vars_clear (htab_t vars)
{
  htab_empty (vars);
}

/* Return a copy of a variable VAR and insert it to dataflow set SET.  */

static variable
unshare_variable (dataflow_set *set, variable var)
{
  void **slot;
  variable new_var;
  int i;

  new_var = pool_alloc (var_pool);
  new_var->decl = var->decl;
  new_var->refcount = 1;
  var->refcount--;
  new_var->n_var_parts = var->n_var_parts;

  for (i = 0; i < var->n_var_parts; i++)
    {
      location_chain node;
      location_chain *nextp;

      new_var->var_part[i].offset = var->var_part[i].offset;
      nextp = &new_var->var_part[i].loc_chain;
      for (node = var->var_part[i].loc_chain; node; node = node->next)
	{
	  location_chain new_lc;

	  new_lc = pool_alloc (loc_chain_pool);
	  new_lc->next = NULL;
	  new_lc->loc = node->loc;

	  *nextp = new_lc;
	  nextp = &new_lc->next;
	}

      /* We are at the basic block boundary when copying variable description
	 so set the CUR_LOC to be the first element of the chain.  */
      if (new_var->var_part[i].loc_chain)
	new_var->var_part[i].cur_loc = new_var->var_part[i].loc_chain->loc;
      else
	new_var->var_part[i].cur_loc = NULL;
    }

  slot = htab_find_slot_with_hash (set->vars, new_var->decl,
				   VARIABLE_HASH_VAL (new_var->decl),
				   INSERT);
  *slot = new_var;
  return new_var;
}

/* Add a variable from *SLOT to hash table DATA and increase its reference
   count.  */

static int
vars_copy_1 (void **slot, void *data)
{
  htab_t dst = (htab_t) data;
  variable src, *dstp;

  src = *(variable *) slot;
  src->refcount++;

  dstp = (variable *) htab_find_slot_with_hash (dst, src->decl,
						VARIABLE_HASH_VAL (src->decl),
						INSERT);
  *dstp = src;

  /* Continue traversing the hash table.  */
  return 1;
}

/* Copy all variables from hash table SRC to hash table DST.  */

static void
vars_copy (htab_t dst, htab_t src)
{
  vars_clear (dst);
  htab_traverse (src, vars_copy_1, dst);
}

/* Map a decl to its main debug decl.  */

static inline tree
var_debug_decl (tree decl)
{
  if (decl && DECL_P (decl)
      && DECL_DEBUG_EXPR_IS_FROM (decl) && DECL_DEBUG_EXPR (decl)
      && DECL_P (DECL_DEBUG_EXPR (decl)))
    decl = DECL_DEBUG_EXPR (decl);

  return decl;
}

/* Set the register to contain REG_EXPR (LOC), REG_OFFSET (LOC).  */

static void
var_reg_set (dataflow_set *set, rtx loc)
{
  tree decl = REG_EXPR (loc);
  HOST_WIDE_INT offset = REG_OFFSET (loc);
  attrs node;

  decl = var_debug_decl (decl);

  for (node = set->regs[REGNO (loc)]; node; node = node->next)
    if (node->decl == decl && node->offset == offset)
      break;
  if (!node)
    attrs_list_insert (&set->regs[REGNO (loc)], decl, offset, loc);
  set_variable_part (set, loc, decl, offset);
}

/* Delete current content of register LOC in dataflow set SET and set
   the register to contain REG_EXPR (LOC), REG_OFFSET (LOC).  If
   MODIFY is true, any other live copies of the same variable part are
   also deleted from the dataflow set, otherwise the variable part is
   assumed to be copied from another location holding the same
   part.  */

static void
var_reg_delete_and_set (dataflow_set *set, rtx loc, bool modify)
{
  tree decl = REG_EXPR (loc);
  HOST_WIDE_INT offset = REG_OFFSET (loc);
  attrs node, next;
  attrs *nextp;

  decl = var_debug_decl (decl);

  nextp = &set->regs[REGNO (loc)];
  for (node = *nextp; node; node = next)
    {
      next = node->next;
      if (node->decl != decl || node->offset != offset)
	{
	  delete_variable_part (set, node->loc, node->decl, node->offset);
	  pool_free (attrs_pool, node);
	  *nextp = next;
	}
      else
	{
	  node->loc = loc;
	  nextp = &node->next;
	}
    }
  if (modify)
    clobber_variable_part (set, loc, decl, offset);
  var_reg_set (set, loc);
}

/* Delete current content of register LOC in dataflow set SET.  If
   CLOBBER is true, also delete any other live copies of the same
   variable part.  */

static void
var_reg_delete (dataflow_set *set, rtx loc, bool clobber)
{
  attrs *reg = &set->regs[REGNO (loc)];
  attrs node, next;

  if (clobber)
    {
      tree decl = REG_EXPR (loc);
      HOST_WIDE_INT offset = REG_OFFSET (loc);

      decl = var_debug_decl (decl);

      clobber_variable_part (set, NULL, decl, offset);
    }

  for (node = *reg; node; node = next)
    {
      next = node->next;
      delete_variable_part (set, node->loc, node->decl, node->offset);
      pool_free (attrs_pool, node);
    }
  *reg = NULL;
}

/* Delete content of register with number REGNO in dataflow set SET.  */

static void
var_regno_delete (dataflow_set *set, int regno)
{
  attrs *reg = &set->regs[regno];
  attrs node, next;

  for (node = *reg; node; node = next)
    {
      next = node->next;
      delete_variable_part (set, node->loc, node->decl, node->offset);
      pool_free (attrs_pool, node);
    }
  *reg = NULL;
}

/* Set the location part of variable MEM_EXPR (LOC) in dataflow set
   SET to LOC.
   Adjust the address first if it is stack pointer based.  */

static void
var_mem_set (dataflow_set *set, rtx loc)
{
  tree decl = MEM_EXPR (loc);
  HOST_WIDE_INT offset = INT_MEM_OFFSET (loc);

  decl = var_debug_decl (decl);

  set_variable_part (set, loc, decl, offset);
}

/* Delete and set the location part of variable MEM_EXPR (LOC) in
   dataflow set SET to LOC.  If MODIFY is true, any other live copies
   of the same variable part are also deleted from the dataflow set,
   otherwise the variable part is assumed to be copied from another
   location holding the same part.
   Adjust the address first if it is stack pointer based.  */

static void
var_mem_delete_and_set (dataflow_set *set, rtx loc, bool modify)
{
  tree decl = MEM_EXPR (loc);
  HOST_WIDE_INT offset = INT_MEM_OFFSET (loc);

  decl = var_debug_decl (decl);

  if (modify)
    clobber_variable_part (set, NULL, decl, offset);
  var_mem_set (set, loc);
}

/* Delete the location part LOC from dataflow set SET.  If CLOBBER is
   true, also delete any other live copies of the same variable part.
   Adjust the address first if it is stack pointer based.  */

static void
var_mem_delete (dataflow_set *set, rtx loc, bool clobber)
{
  tree decl = MEM_EXPR (loc);
  HOST_WIDE_INT offset = INT_MEM_OFFSET (loc);

  decl = var_debug_decl (decl);
  if (clobber)
    clobber_variable_part (set, NULL, decl, offset);
  delete_variable_part (set, loc, decl, offset);
}

/* Initialize dataflow set SET to be empty. 
   VARS_SIZE is the initial size of hash table VARS.  */

static void
dataflow_set_init (dataflow_set *set, int vars_size)
{
  init_attrs_list_set (set->regs);
  set->vars = htab_create (vars_size, variable_htab_hash, variable_htab_eq,
			   variable_htab_free);
  set->stack_adjust = 0;
}

/* Delete the contents of dataflow set SET.  */

static void
dataflow_set_clear (dataflow_set *set)
{
  int i;

  for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
    attrs_list_clear (&set->regs[i]);

  vars_clear (set->vars);
}

/* Copy the contents of dataflow set SRC to DST.  */

static void
dataflow_set_copy (dataflow_set *dst, dataflow_set *src)
{
  int i;

  for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
    attrs_list_copy (&dst->regs[i], src->regs[i]);

  vars_copy (dst->vars, src->vars);
  dst->stack_adjust = src->stack_adjust;
}

/* Information for merging lists of locations for a given offset of variable.
 */
struct variable_union_info
{
  /* Node of the location chain.  */
  location_chain lc;

  /* The sum of positions in the input chains.  */
  int pos;

  /* The position in the chains of SRC and DST dataflow sets.  */
  int pos_src;
  int pos_dst;
};

/* Compare function for qsort, order the structures by POS element.  */

static int
variable_union_info_cmp_pos (const void *n1, const void *n2)
{
  const struct variable_union_info *i1 = n1;
  const struct variable_union_info *i2 = n2;

  if (i1->pos != i2->pos)
    return i1->pos - i2->pos;
  
  return (i1->pos_dst - i2->pos_dst);
}

/* Compute union of location parts of variable *SLOT and the same variable
   from hash table DATA.  Compute "sorted" union of the location chains
   for common offsets, i.e. the locations of a variable part are sorted by
   a priority where the priority is the sum of the positions in the 2 chains
   (if a location is only in one list the position in the second list is
   defined to be larger than the length of the chains).
   When we are updating the location parts the newest location is in the
   beginning of the chain, so when we do the described "sorted" union
   we keep the newest locations in the beginning.  */

static int
variable_union (void **slot, void *data)
{
  variable src, dst, *dstp;
  dataflow_set *set = (dataflow_set *) data;
  int i, j, k;

  src = *(variable *) slot;
  dstp = (variable *) htab_find_slot_with_hash (set->vars, src->decl,
						VARIABLE_HASH_VAL (src->decl),
						INSERT);
  if (!*dstp)
    {
      src->refcount++;

      /* If CUR_LOC of some variable part is not the first element of
	 the location chain we are going to change it so we have to make
	 a copy of the variable.  */
      for (k = 0; k < src->n_var_parts; k++)
	{
	  gcc_assert (!src->var_part[k].loc_chain
		      == !src->var_part[k].cur_loc);
	  if (src->var_part[k].loc_chain)
	    {
	      gcc_assert (src->var_part[k].cur_loc);
	      if (src->var_part[k].cur_loc != src->var_part[k].loc_chain->loc)
		break;
	    }
	}
      if (k < src->n_var_parts)
	unshare_variable (set, src);
      else
	*dstp = src;

      /* Continue traversing the hash table.  */
      return 1;
    }
  else
    dst = *dstp;

  gcc_assert (src->n_var_parts);

  /* Count the number of location parts, result is K.  */
  for (i = 0, j = 0, k = 0;
       i < src->n_var_parts && j < dst->n_var_parts; k++)
    {
      if (src->var_part[i].offset == dst->var_part[j].offset)
	{
	  i++;
	  j++;
	}
      else if (src->var_part[i].offset < dst->var_part[j].offset)
	i++;
      else
	j++;
    }
  k += src->n_var_parts - i;
  k += dst->n_var_parts - j;

  /* We track only variables whose size is <= MAX_VAR_PARTS bytes
     thus there are at most MAX_VAR_PARTS different offsets.  */
  gcc_assert (k <= MAX_VAR_PARTS);

  if (dst->refcount > 1 && dst->n_var_parts != k)
    dst = unshare_variable (set, dst);

  i = src->n_var_parts - 1;
  j = dst->n_var_parts - 1;
  dst->n_var_parts = k;

  for (k--; k >= 0; k--)
    {
      location_chain node, node2;

      if (i >= 0 && j >= 0
	  && src->var_part[i].offset == dst->var_part[j].offset)
	{
	  /* Compute the "sorted" union of the chains, i.e. the locations which
	     are in both chains go first, they are sorted by the sum of
	     positions in the chains.  */
	  int dst_l, src_l;
	  int ii, jj, n;
	  struct variable_union_info *vui;

	  /* If DST is shared compare the location chains.
	     If they are different we will modify the chain in DST with
	     high probability so make a copy of DST.  */
	  if (dst->refcount > 1)
	    {
	      for (node = src->var_part[i].loc_chain,
		   node2 = dst->var_part[j].loc_chain; node && node2;
		   node = node->next, node2 = node2->next)
		{
		  if (!((REG_P (node2->loc)
			 && REG_P (node->loc)
			 && REGNO (node2->loc) == REGNO (node->loc))
			|| rtx_equal_p (node2->loc, node->loc)))
		    break;
		}
	      if (node || node2)
		dst = unshare_variable (set, dst);
	    }

	  src_l = 0;
	  for (node = src->var_part[i].loc_chain; node; node = node->next)
	    src_l++;
	  dst_l = 0;
	  for (node = dst->var_part[j].loc_chain; node; node = node->next)
	    dst_l++;
	  vui = XCNEWVEC (struct variable_union_info, src_l + dst_l);

	  /* Fill in the locations from DST.  */
	  for (node = dst->var_part[j].loc_chain, jj = 0; node;
	       node = node->next, jj++)
	    {
	      vui[jj].lc = node;
	      vui[jj].pos_dst = jj;

	      /* Value larger than a sum of 2 valid positions.  */
	      vui[jj].pos_src = src_l + dst_l;
	    }

	  /* Fill in the locations from SRC.  */
	  n = dst_l;
	  for (node = src->var_part[i].loc_chain, ii = 0; node;
	       node = node->next, ii++)
	    {
	      /* Find location from NODE.  */
	      for (jj = 0; jj < dst_l; jj++)
		{
		  if ((REG_P (vui[jj].lc->loc)
		       && REG_P (node->loc)
		       && REGNO (vui[jj].lc->loc) == REGNO (node->loc))
		      || rtx_equal_p (vui[jj].lc->loc, node->loc))
		    {
		      vui[jj].pos_src = ii;
		      break;
		    }
		}
	      if (jj >= dst_l)	/* The location has not been found.  */
		{
		  location_chain new_node;

		  /* Copy the location from SRC.  */
		  new_node = pool_alloc (loc_chain_pool);
		  new_node->loc = node->loc;
		  vui[n].lc = new_node;
		  vui[n].pos_src = ii;
		  vui[n].pos_dst = src_l + dst_l;
		  n++;
		}
	    }

	  for (ii = 0; ii < src_l + dst_l; ii++)
	    vui[ii].pos = vui[ii].pos_src + vui[ii].pos_dst;

	  qsort (vui, n, sizeof (struct variable_union_info),
		 variable_union_info_cmp_pos);

	  /* Reconnect the nodes in sorted order.  */
	  for (ii = 1; ii < n; ii++)
	    vui[ii - 1].lc->next = vui[ii].lc;
	  vui[n - 1].lc->next = NULL;

	  dst->var_part[k].loc_chain = vui[0].lc;
	  dst->var_part[k].offset = dst->var_part[j].offset;

	  free (vui);
	  i--;
	  j--;
	}
      else if ((i >= 0 && j >= 0
		&& src->var_part[i].offset < dst->var_part[j].offset)
	       || i < 0)
	{
	  dst->var_part[k] = dst->var_part[j];
	  j--;
	}
      else if ((i >= 0 && j >= 0
		&& src->var_part[i].offset > dst->var_part[j].offset)
	       || j < 0)
	{
	  location_chain *nextp;

	  /* Copy the chain from SRC.  */
	  nextp = &dst->var_part[k].loc_chain;
	  for (node = src->var_part[i].loc_chain; node; node = node->next)
	    {
	      location_chain new_lc;

	      new_lc = pool_alloc (loc_chain_pool);
	      new_lc->next = NULL;
	      new_lc->loc = node->loc;

	      *nextp = new_lc;
	      nextp = &new_lc->next;
	    }

	  dst->var_part[k].offset = src->var_part[i].offset;
	  i--;
	}

      /* We are at the basic block boundary when computing union
	 so set the CUR_LOC to be the first element of the chain.  */
      if (dst->var_part[k].loc_chain)
	dst->var_part[k].cur_loc = dst->var_part[k].loc_chain->loc;
      else
	dst->var_part[k].cur_loc = NULL;
    }

  /* Continue traversing the hash table.  */
  return 1;
}

/* Compute union of dataflow sets SRC and DST and store it to DST.  */

static void
dataflow_set_union (dataflow_set *dst, dataflow_set *src)
{
  int i;

  for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
    attrs_list_union (&dst->regs[i], src->regs[i]);

  htab_traverse (src->vars, variable_union, dst);
}

/* Flag whether two dataflow sets being compared contain different data.  */
static bool
dataflow_set_different_value;

static bool
variable_part_different_p (variable_part *vp1, variable_part *vp2)
{
  location_chain lc1, lc2;

  for (lc1 = vp1->loc_chain; lc1; lc1 = lc1->next)
    {
      for (lc2 = vp2->loc_chain; lc2; lc2 = lc2->next)
	{
	  if (REG_P (lc1->loc) && REG_P (lc2->loc))
	    {
	      if (REGNO (lc1->loc) == REGNO (lc2->loc))
		break;
	    }
	  if (rtx_equal_p (lc1->loc, lc2->loc))
	    break;
	}
      if (!lc2)
	return true;
    }
  return false;
}

/* Return true if variables VAR1 and VAR2 are different.
   If COMPARE_CURRENT_LOCATION is true compare also the cur_loc of each
   variable part.  */

static bool
variable_different_p (variable var1, variable var2,
		      bool compare_current_location)
{
  int i;

  if (var1 == var2)
    return false;

  if (var1->n_var_parts != var2->n_var_parts)
    return true;

  for (i = 0; i < var1->n_var_parts; i++)
    {
      if (var1->var_part[i].offset != var2->var_part[i].offset)
	return true;
      if (compare_current_location)
	{
	  if (!((REG_P (var1->var_part[i].cur_loc)
		 && REG_P (var2->var_part[i].cur_loc)
		 && (REGNO (var1->var_part[i].cur_loc)
		     == REGNO (var2->var_part[i].cur_loc)))
		|| rtx_equal_p (var1->var_part[i].cur_loc,
				var2->var_part[i].cur_loc)))
	    return true;
	}
      if (variable_part_different_p (&var1->var_part[i], &var2->var_part[i]))
	return true;
      if (variable_part_different_p (&var2->var_part[i], &var1->var_part[i]))
	return true;
    }
  return false;
}

/* Compare variable *SLOT with the same variable in hash table DATA
   and set DATAFLOW_SET_DIFFERENT_VALUE if they are different.  */

static int
dataflow_set_different_1 (void **slot, void *data)
{
  htab_t htab = (htab_t) data;
  variable var1, var2;

  var1 = *(variable *) slot;
  var2 = htab_find_with_hash (htab, var1->decl,
			      VARIABLE_HASH_VAL (var1->decl));
  if (!var2)
    {
      dataflow_set_different_value = true;

      /* Stop traversing the hash table.  */
      return 0;
    }

  if (variable_different_p (var1, var2, false))
    {
      dataflow_set_different_value = true;

      /* Stop traversing the hash table.  */
      return 0;
    }

  /* Continue traversing the hash table.  */
  return 1;
}

/* Compare variable *SLOT with the same variable in hash table DATA
   and set DATAFLOW_SET_DIFFERENT_VALUE if they are different.  */

static int
dataflow_set_different_2 (void **slot, void *data)
{
  htab_t htab = (htab_t) data;
  variable var1, var2;

  var1 = *(variable *) slot;
  var2 = htab_find_with_hash (htab, var1->decl,
			      VARIABLE_HASH_VAL (var1->decl));
  if (!var2)
    {
      dataflow_set_different_value = true;

      /* Stop traversing the hash table.  */
      return 0;
    }

  /* If both variables are defined they have been already checked for
     equivalence.  */
  gcc_assert (!variable_different_p (var1, var2, false));

  /* Continue traversing the hash table.  */
  return 1;
}

/* Return true if dataflow sets OLD_SET and NEW_SET differ.  */

static bool
dataflow_set_different (dataflow_set *old_set, dataflow_set *new_set)
{
  dataflow_set_different_value = false;

  htab_traverse (old_set->vars, dataflow_set_different_1, new_set->vars);
  if (!dataflow_set_different_value)
    {
      /* We have compared the variables which are in both hash tables
	 so now only check whether there are some variables in NEW_SET->VARS
	 which are not in OLD_SET->VARS.  */
      htab_traverse (new_set->vars, dataflow_set_different_2, old_set->vars);
    }
  return dataflow_set_different_value;
}

/* Free the contents of dataflow set SET.  */

static void
dataflow_set_destroy (dataflow_set *set)
{
  int i;

  for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
    attrs_list_clear (&set->regs[i]);

  htab_delete (set->vars);
  set->vars = NULL;
}

/* Return true if RTL X contains a SYMBOL_REF.  */

static bool
contains_symbol_ref (rtx x)
{
  const char *fmt;
  RTX_CODE code;
  int i;

  if (!x)
    return false;

  code = GET_CODE (x);
  if (code == SYMBOL_REF)
    return true;

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

  return false;
}

/* Shall EXPR be tracked?  */

static bool
track_expr_p (tree expr)
{
  rtx decl_rtl;
  tree realdecl;

  /* If EXPR is not a parameter or a variable do not track it.  */
  if (TREE_CODE (expr) != VAR_DECL && TREE_CODE (expr) != PARM_DECL)
    return 0;

  /* It also must have a name...  */
  if (!DECL_NAME (expr))
    return 0;

  /* ... and a RTL assigned to it.  */
  decl_rtl = DECL_RTL_IF_SET (expr);
  if (!decl_rtl)
    return 0;
  
  /* If this expression is really a debug alias of some other declaration, we 
     don't need to track this expression if the ultimate declaration is
     ignored.  */
  realdecl = expr;
  if (DECL_DEBUG_EXPR_IS_FROM (realdecl) && DECL_DEBUG_EXPR (realdecl))
    {
      realdecl = DECL_DEBUG_EXPR (realdecl);
      /* ??? We don't yet know how to emit DW_OP_piece for variable
	 that has been SRA'ed.  */
      if (!DECL_P (realdecl))
	return 0;
    }

  /* Do not track EXPR if REALDECL it should be ignored for debugging
     purposes.  */ 
  if (DECL_IGNORED_P (realdecl))
    return 0;

  /* Do not track global variables until we are able to emit correct location
     list for them.  */
  if (TREE_STATIC (realdecl))
    return 0;

  /* When the EXPR is a DECL for alias of some variable (see example)
     the TREE_STATIC flag is not used.  Disable tracking all DECLs whose
     DECL_RTL contains SYMBOL_REF.

     Example:
     extern char **_dl_argv_internal __attribute__ ((alias ("_dl_argv")));
     char **_dl_argv;
  */
  if (MEM_P (decl_rtl)
      && contains_symbol_ref (XEXP (decl_rtl, 0)))
    return 0;

  /* If RTX is a memory it should not be very large (because it would be
     an array or struct).  */
  if (MEM_P (decl_rtl))
    {
      /* Do not track structures and arrays.  */
      if (GET_MODE (decl_rtl) == BLKmode
	  || AGGREGATE_TYPE_P (TREE_TYPE (realdecl)))
	return 0;
      if (MEM_SIZE (decl_rtl)
	  && INTVAL (MEM_SIZE (decl_rtl)) > MAX_VAR_PARTS)
	return 0;
    }

  return 1;
}

/* Return true if OFFSET is a valid offset for a register or memory
   access we want to track.  This is used to reject out-of-bounds
   accesses that can cause assertions to fail later.  Note that we
   don't reject negative offsets because they can be generated for
   paradoxical subregs on big-endian architectures.  */

static inline bool
offset_valid_for_tracked_p (HOST_WIDE_INT offset)
{
  return (-MAX_VAR_PARTS < offset) && (offset < MAX_VAR_PARTS);
}

/* Determine whether a given LOC refers to the same variable part as
   EXPR+OFFSET.  */

static bool
same_variable_part_p (rtx loc, tree expr, HOST_WIDE_INT offset)
{
  tree expr2;
  HOST_WIDE_INT offset2;

  if (! DECL_P (expr))
    return false;

  if (REG_P (loc))
    {
      expr2 = REG_EXPR (loc);
      offset2 = REG_OFFSET (loc);
    }
  else if (MEM_P (loc))
    {
      expr2 = MEM_EXPR (loc);
      offset2 = INT_MEM_OFFSET (loc);
    }
  else
    return false;

  if (! expr2 || ! DECL_P (expr2))
    return false;

  expr = var_debug_decl (expr);
  expr2 = var_debug_decl (expr2);

  return (expr == expr2 && offset == offset2);
}


/* Count uses (register and memory references) LOC which will be tracked.
   INSN is instruction which the LOC is part of.  */

static int
count_uses (rtx *loc, void *insn)
{
  basic_block bb = BLOCK_FOR_INSN ((rtx) insn);

  if (REG_P (*loc))
    {
      gcc_assert (REGNO (*loc) < FIRST_PSEUDO_REGISTER);
      VTI (bb)->n_mos++;
    }
  else if (MEM_P (*loc)
	   && MEM_EXPR (*loc)
	   && track_expr_p (MEM_EXPR (*loc))
	   && offset_valid_for_tracked_p (INT_MEM_OFFSET (*loc)))
    {
      VTI (bb)->n_mos++;
    }

  return 0;
}

/* Helper function for finding all uses of REG/MEM in X in insn INSN.  */

static void
count_uses_1 (rtx *x, void *insn)
{
  for_each_rtx (x, count_uses, insn);
}

/* Count stores (register and memory references) LOC which will be tracked.
   INSN is instruction which the LOC is part of.  */

static void
count_stores (rtx loc, rtx expr ATTRIBUTE_UNUSED, void *insn)
{
  count_uses (&loc, insn);
}

/* Add uses (register and memory references) LOC which will be tracked
   to VTI (bb)->mos.  INSN is instruction which the LOC is part of.  */

static int
add_uses (rtx *loc, void *insn)
{
  if (REG_P (*loc))
    {
      basic_block bb = BLOCK_FOR_INSN ((rtx) insn);
      micro_operation *mo = VTI (bb)->mos + VTI (bb)->n_mos++;

      if (REG_EXPR (*loc)
	  && track_expr_p (REG_EXPR (*loc))
	  && offset_valid_for_tracked_p (REG_OFFSET (*loc)))
	mo->type = MO_USE;
      else
	mo->type = MO_USE_NO_VAR;
      mo->u.loc = *loc;
      mo->insn = (rtx) insn;
    }
  else if (MEM_P (*loc)
	   && MEM_EXPR (*loc)
	   && track_expr_p (MEM_EXPR (*loc))
	   && offset_valid_for_tracked_p (INT_MEM_OFFSET (*loc)))
    {
      basic_block bb = BLOCK_FOR_INSN ((rtx) insn);
      micro_operation *mo = VTI (bb)->mos + VTI (bb)->n_mos++;

      mo->type = MO_USE;
      mo->u.loc = *loc;
      mo->insn = (rtx) insn;
    }

  return 0;
}

/* Helper function for finding all uses of REG/MEM in X in insn INSN.  */

static void
add_uses_1 (rtx *x, void *insn)
{
  for_each_rtx (x, add_uses, insn);
}

/* Add stores (register and memory references) LOC which will be tracked
   to VTI (bb)->mos. EXPR is the RTL expression containing the store.
   INSN is instruction which the LOC is part of.  */

static void
add_stores (rtx loc, rtx expr, void *insn)
{
  if (REG_P (loc))
    {
      basic_block bb = BLOCK_FOR_INSN ((rtx) insn);
      micro_operation *mo = VTI (bb)->mos + VTI (bb)->n_mos++;

      if (GET_CODE (expr) == CLOBBER
	  || !(REG_EXPR (loc)
	       && track_expr_p (REG_EXPR (loc))
	       && offset_valid_for_tracked_p (REG_OFFSET (loc))))
	mo->type = MO_CLOBBER;
      else if (GET_CODE (expr) == SET
	       && SET_DEST (expr) == loc
	       && same_variable_part_p (SET_SRC (expr),
					REG_EXPR (loc),
					REG_OFFSET (loc)))
	mo->type = MO_COPY;
      else
	mo->type = MO_SET;
      mo->u.loc = loc;
      mo->insn = NEXT_INSN ((rtx) insn);
    }
  else if (MEM_P (loc)
	   && MEM_EXPR (loc)
	   && track_expr_p (MEM_EXPR (loc))
	   && offset_valid_for_tracked_p (INT_MEM_OFFSET (loc)))
    {
      basic_block bb = BLOCK_FOR_INSN ((rtx) insn);
      micro_operation *mo = VTI (bb)->mos + VTI (bb)->n_mos++;

      if (GET_CODE (expr) == CLOBBER)
	mo->type = MO_CLOBBER;
      else if (GET_CODE (expr) == SET
	       && SET_DEST (expr) == loc
	       && same_variable_part_p (SET_SRC (expr),
					MEM_EXPR (loc),
					INT_MEM_OFFSET (loc)))
	mo->type = MO_COPY;
      else
	mo->type = MO_SET;
      mo->u.loc = loc;
      mo->insn = NEXT_INSN ((rtx) insn);
    }
}

/* Compute the changes of variable locations in the basic block BB.  */

static bool
compute_bb_dataflow (basic_block bb)
{
  int i, n, r;
  bool changed;
  dataflow_set old_out;
  dataflow_set *in = &VTI (bb)->in;
  dataflow_set *out = &VTI (bb)->out;

  dataflow_set_init (&old_out, htab_elements (VTI (bb)->out.vars) + 3);
  dataflow_set_copy (&old_out, out);
  dataflow_set_copy (out, in);

  n = VTI (bb)->n_mos;
  for (i = 0; i < n; i++)
    {
      switch (VTI (bb)->mos[i].type)
	{
	  case MO_CALL:
	    for (r = 0; r < FIRST_PSEUDO_REGISTER; r++)
	      if (TEST_HARD_REG_BIT (call_used_reg_set, r))
		var_regno_delete (out, r);
	    break;

	  case MO_USE:
	    {
	      rtx loc = VTI (bb)->mos[i].u.loc;

	      if (GET_CODE (loc) == REG)
		var_reg_set (out, loc);
	      else if (GET_CODE (loc) == MEM)
		var_mem_set (out, loc);
	    }
	    break;

	  case MO_SET:
	    {
	      rtx loc = VTI (bb)->mos[i].u.loc;

	      if (REG_P (loc))
		var_reg_delete_and_set (out, loc, true);
	      else if (MEM_P (loc))
		var_mem_delete_and_set (out, loc, true);
	    }
	    break;

	  case MO_COPY:
	    {
	      rtx loc = VTI (bb)->mos[i].u.loc;

	      if (REG_P (loc))
		var_reg_delete_and_set (out, loc, false);
	      else if (MEM_P (loc))
		var_mem_delete_and_set (out, loc, false);
	    }
	    break;

	  case MO_USE_NO_VAR:
	    {
	      rtx loc = VTI (bb)->mos[i].u.loc;

	      if (REG_P (loc))
		var_reg_delete (out, loc, false);
	      else if (MEM_P (loc))
		var_mem_delete (out, loc, false);
	    }
	    break;

	  case MO_CLOBBER:
	    {
	      rtx loc = VTI (bb)->mos[i].u.loc;

	      if (REG_P (loc))
		var_reg_delete (out, loc, true);
	      else if (MEM_P (loc))
		var_mem_delete (out, loc, true);
	    }
	    break;

	  case MO_ADJUST:
	    out->stack_adjust += VTI (bb)->mos[i].u.adjust;
	    break;
	}
    }

  changed = dataflow_set_different (&old_out, out);
  dataflow_set_destroy (&old_out);
  return changed;
}

/* Find the locations of variables in the whole function.  */

static void
vt_find_locations (void)
{
  fibheap_t worklist, pending, fibheap_swap;
  sbitmap visited, in_worklist, in_pending, sbitmap_swap;
  basic_block bb;
  edge e;
  int *bb_order;
  int *rc_order;
  int i;

  /* Compute reverse completion order of depth first search of the CFG
     so that the data-flow runs faster.  */
  rc_order = XNEWVEC (int, n_basic_blocks - NUM_FIXED_BLOCKS);
  bb_order = XNEWVEC (int, last_basic_block);
  pre_and_rev_post_order_compute (NULL, rc_order, false);
  for (i = 0; i < n_basic_blocks - NUM_FIXED_BLOCKS; i++)
    bb_order[rc_order[i]] = i;
  free (rc_order);

  worklist = fibheap_new ();
  pending = fibheap_new ();
  visited = sbitmap_alloc (last_basic_block);
  in_worklist = sbitmap_alloc (last_basic_block);
  in_pending = sbitmap_alloc (last_basic_block);
  sbitmap_zero (in_worklist);

  FOR_EACH_BB (bb)
    fibheap_insert (pending, bb_order[bb->index], bb);
  sbitmap_ones (in_pending);

  while (!fibheap_empty (pending))
    {
      fibheap_swap = pending;
      pending = worklist;
      worklist = fibheap_swap;
      sbitmap_swap = in_pending;
      in_pending = in_worklist;
      in_worklist = sbitmap_swap;

      sbitmap_zero (visited);

      while (!fibheap_empty (worklist))
	{
	  bb = fibheap_extract_min (worklist);
	  RESET_BIT (in_worklist, bb->index);
	  if (!TEST_BIT (visited, bb->index))
	    {
	      bool changed;
	      edge_iterator ei;

	      SET_BIT (visited, bb->index);

	      /* Calculate the IN set as union of predecessor OUT sets.  */
	      dataflow_set_clear (&VTI (bb)->in);
	      FOR_EACH_EDGE (e, ei, bb->preds)
		{
		  dataflow_set_union (&VTI (bb)->in, &VTI (e->src)->out);
		}

	      changed = compute_bb_dataflow (bb);
	      if (changed)
		{
		  FOR_EACH_EDGE (e, ei, bb->succs)
		    {
		      if (e->dest == EXIT_BLOCK_PTR)
			continue;

		      if (e->dest == bb)
			continue;

		      if (TEST_BIT (visited, e->dest->index))
			{
			  if (!TEST_BIT (in_pending, e->dest->index))
			    {
			      /* Send E->DEST to next round.  */
			      SET_BIT (in_pending, e->dest->index);
			      fibheap_insert (pending,
					      bb_order[e->dest->index],
					      e->dest);
			    }
			}
		      else if (!TEST_BIT (in_worklist, e->dest->index))
			{
			  /* Add E->DEST to current round.  */
			  SET_BIT (in_worklist, e->dest->index);
			  fibheap_insert (worklist, bb_order[e->dest->index],
					  e->dest);
			}
		    }
		}
	    }
	}
    }

  free (bb_order);
  fibheap_delete (worklist);
  fibheap_delete (pending);
  sbitmap_free (visited);
  sbitmap_free (in_worklist);
  sbitmap_free (in_pending);
}

/* Print the content of the LIST to dump file.  */

static void
dump_attrs_list (attrs list)
{
  for (; list; list = list->next)
    {
      print_mem_expr (dump_file, list->decl);
      fprintf (dump_file, "+" HOST_WIDE_INT_PRINT_DEC, list->offset);
    }
  fprintf (dump_file, "\n");
}

/* Print the information about variable *SLOT to dump file.  */

static int
dump_variable (void **slot, void *data ATTRIBUTE_UNUSED)
{
  variable var = *(variable *) slot;
  int i;
  location_chain node;

  fprintf (dump_file, "  name: %s\n",
	   IDENTIFIER_POINTER (DECL_NAME (var->decl)));
  for (i = 0; i < var->n_var_parts; i++)
    {
      fprintf (dump_file, "    offset %ld\n",
	       (long) var->var_part[i].offset);
      for (node = var->var_part[i].loc_chain; node; node = node->next)
	{
	  fprintf (dump_file, "      ");
	  print_rtl_single (dump_file, node->loc);
	}
    }

  /* Continue traversing the hash table.  */
  return 1;
}

/* Print the information about variables from hash table VARS to dump file.  */

static void
dump_vars (htab_t vars)
{
  if (htab_elements (vars) > 0)
    {
      fprintf (dump_file, "Variables:\n");
      htab_traverse (vars, dump_variable, NULL);
    }
}

/* Print the dataflow set SET to dump file.  */

static void
dump_dataflow_set (dataflow_set *set)
{
  int i;

  fprintf (dump_file, "Stack adjustment: " HOST_WIDE_INT_PRINT_DEC "\n",
	   set->stack_adjust);
  for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
    {
      if (set->regs[i])
	{
	  fprintf (dump_file, "Reg %d:", i);
	  dump_attrs_list (set->regs[i]);
	}
    }
  dump_vars (set->vars);
  fprintf (dump_file, "\n");
}

/* Print the IN and OUT sets for each basic block to dump file.  */

static void
dump_dataflow_sets (void)
{
  basic_block bb;

  FOR_EACH_BB (bb)
    {
      fprintf (dump_file, "\nBasic block %d:\n", bb->index);
      fprintf (dump_file, "IN:\n");
      dump_dataflow_set (&VTI (bb)->in);
      fprintf (dump_file, "OUT:\n");
      dump_dataflow_set (&VTI (bb)->out);
    }
}

/* Add variable VAR to the hash table of changed variables and
   if it has no locations delete it from hash table HTAB.  */

static void
variable_was_changed (variable var, htab_t htab)
{
  hashval_t hash = VARIABLE_HASH_VAL (var->decl);

  if (emit_notes)
    {
      variable *slot;

      slot = (variable *) htab_find_slot_with_hash (changed_variables,
						    var->decl, hash, INSERT);

      if (htab && var->n_var_parts == 0)
	{
	  variable empty_var;
	  void **old;

	  empty_var = pool_alloc (var_pool);
	  empty_var->decl = var->decl;
	  empty_var->refcount = 1;
	  empty_var->n_var_parts = 0;
	  *slot = empty_var;

	  old = htab_find_slot_with_hash (htab, var->decl, hash,
					  NO_INSERT);
	  if (old)
	    htab_clear_slot (htab, old);
	}
      else
	{
	  *slot = var;
	}
    }
  else
    {
      gcc_assert (htab);
      if (var->n_var_parts == 0)
	{
	  void **slot = htab_find_slot_with_hash (htab, var->decl, hash,
						  NO_INSERT);
	  if (slot)
	    htab_clear_slot (htab, slot);
	}
    }
}

/* Look for the index in VAR->var_part corresponding to OFFSET.
   Return -1 if not found.  If INSERTION_POINT is non-NULL, the
   referenced int will be set to the index that the part has or should
   have, if it should be inserted.  */

static inline int
find_variable_location_part (variable var, HOST_WIDE_INT offset,
			     int *insertion_point)
{
  int pos, low, high;

  /* Find the location part.  */
  low = 0;
  high = var->n_var_parts;
  while (low != high)
    {
      pos = (low + high) / 2;
      if (var->var_part[pos].offset < offset)
	low = pos + 1;
      else
	high = pos;
    }
  pos = low;

  if (insertion_point)
    *insertion_point = pos;

  if (pos < var->n_var_parts && var->var_part[pos].offset == offset)
    return pos;

  return -1;
}

/* Set the part of variable's location in the dataflow set SET.  The variable
   part is specified by variable's declaration DECL and offset OFFSET and the
   part's location by LOC.  */

static void
set_variable_part (dataflow_set *set, rtx loc, tree decl, HOST_WIDE_INT offset)
{
  int pos;
  location_chain node, next;
  location_chain *nextp;
  variable var;
  void **slot;
  
  slot = htab_find_slot_with_hash (set->vars, decl,
				   VARIABLE_HASH_VAL (decl), INSERT);
  if (!*slot)
    {
      /* Create new variable information.  */
      var = pool_alloc (var_pool);
      var->decl = decl;
      var->refcount = 1;
      var->n_var_parts = 1;
      var->var_part[0].offset = offset;
      var->var_part[0].loc_chain = NULL;
      var->var_part[0].cur_loc = NULL;
      *slot = var;
      pos = 0;
    }
  else
    {
      int inspos = 0;

      var = (variable) *slot;

      pos = find_variable_location_part (var, offset, &inspos);

      if (pos >= 0)
	{
	  node = var->var_part[pos].loc_chain;

	  if (node
	      && ((REG_P (node->loc) && REG_P (loc)
		   && REGNO (node->loc) == REGNO (loc))
		  || rtx_equal_p (node->loc, loc)))
	    {
	      /* LOC is in the beginning of the chain so we have nothing
		 to do.  */
	      return;
	    }
	  else
	    {
	      /* We have to make a copy of a shared variable.  */
	      if (var->refcount > 1)
		var = unshare_variable (set, var);
	    }
	}
      else
	{
	  /* We have not found the location part, new one will be created.  */

	  /* We have to make a copy of the shared variable.  */
	  if (var->refcount > 1)
	    var = unshare_variable (set, var);

	  /* We track only variables whose size is <= MAX_VAR_PARTS bytes
	     thus there are at most MAX_VAR_PARTS different offsets.  */
	  gcc_assert (var->n_var_parts < MAX_VAR_PARTS);

	  /* We have to move the elements of array starting at index
	     inspos to the next position.  */
	  for (pos = var->n_var_parts; pos > inspos; pos--)
	    var->var_part[pos] = var->var_part[pos - 1];

	  var->n_var_parts++;
	  var->var_part[pos].offset = offset;
	  var->var_part[pos].loc_chain = NULL;
	  var->var_part[pos].cur_loc = NULL;
	}
    }

  /* Delete the location from the list.  */
  nextp = &var->var_part[pos].loc_chain;
  for (node = var->var_part[pos].loc_chain; node; node = next)
    {
      next = node->next;
      if ((REG_P (node->loc) && REG_P (loc)
	   && REGNO (node->loc) == REGNO (loc))
	  || rtx_equal_p (node->loc, loc))
	{
	  pool_free (loc_chain_pool, node);
	  *nextp = next;
	  break;
	}
      else
	nextp = &node->next;
    }

  /* Add the location to the beginning.  */
  node = pool_alloc (loc_chain_pool);
  node->loc = loc;
  node->next = var->var_part[pos].loc_chain;
  var->var_part[pos].loc_chain = node;

  /* If no location was emitted do so.  */
  if (var->var_part[pos].cur_loc == NULL)
    {
      var->var_part[pos].cur_loc = loc;
      variable_was_changed (var, set->vars);
    }
}

/* Remove all recorded register locations for the given variable part
   from dataflow set SET, except for those that are identical to loc.
   The variable part is specified by variable's declaration DECL and
   offset OFFSET.  */

static void
clobber_variable_part (dataflow_set *set, rtx loc, tree decl,
		      HOST_WIDE_INT offset)
{
  void **slot;

  if (! decl || ! DECL_P (decl))
    return;

  slot = htab_find_slot_with_hash (set->vars, decl, VARIABLE_HASH_VAL (decl),
				   NO_INSERT);
  if (slot)
    {
      variable var = (variable) *slot;
      int pos = find_variable_location_part (var, offset, NULL);

      if (pos >= 0)
	{
	  location_chain node, next;

	  /* Remove the register locations from the dataflow set.  */
	  next = var->var_part[pos].loc_chain;
	  for (node = next; node; node = next)
	    {
	      next = node->next;
	      if (node->loc != loc)
		{
		  if (REG_P (node->loc))
		    {
		      attrs anode, anext;
		      attrs *anextp;

		      /* Remove the variable part from the register's
			 list, but preserve any other variable parts
			 that might be regarded as live in that same
			 register.  */
		      anextp = &set->regs[REGNO (node->loc)];
		      for (anode = *anextp; anode; anode = anext)
			{
			  anext = anode->next;
			  if (anode->decl == decl
			      && anode->offset == offset)
			    {
			      pool_free (attrs_pool, anode);
			      *anextp = anext;
			    }
			}
		    }

		  delete_variable_part (set, node->loc, decl, offset);
		}
	    }
	}
    }
}

/* Delete the part of variable's location from dataflow set SET.  The variable
   part is specified by variable's declaration DECL and offset OFFSET and the
   part's location by LOC.  */

static void
delete_variable_part (dataflow_set *set, rtx loc, tree decl,
		      HOST_WIDE_INT offset)
{
  void **slot;
    
  slot = htab_find_slot_with_hash (set->vars, decl, VARIABLE_HASH_VAL (decl),
				   NO_INSERT);
  if (slot)
    {
      variable var = (variable) *slot;
      int pos = find_variable_location_part (var, offset, NULL);

      if (pos >= 0)
	{
	  location_chain node, next;
	  location_chain *nextp;
	  bool changed;

	  if (var->refcount > 1)
	    {
	      /* If the variable contains the location part we have to
		 make a copy of the variable.  */
	      for (node = var->var_part[pos].loc_chain; node;
		   node = node->next)
		{
		  if ((REG_P (node->loc) && REG_P (loc)
		       && REGNO (node->loc) == REGNO (loc))
		      || rtx_equal_p (node->loc, loc))
		    {
		      var = unshare_variable (set, var);
		      break;
		    }
		}
	    }

	  /* Delete the location part.  */
	  nextp = &var->var_part[pos].loc_chain;
	  for (node = *nextp; node; node = next)
	    {
	      next = node->next;
	      if ((REG_P (node->loc) && REG_P (loc)
		   && REGNO (node->loc) == REGNO (loc))
		  || rtx_equal_p (node->loc, loc))
		{
		  pool_free (loc_chain_pool, node);
		  *nextp = next;
		  break;
		}
	      else
		nextp = &node->next;
	    }

	  /* If we have deleted the location which was last emitted
	     we have to emit new location so add the variable to set
	     of changed variables.  */
	  if (var->var_part[pos].cur_loc
	      && ((REG_P (loc)
		   && REG_P (var->var_part[pos].cur_loc)
		   && REGNO (loc) == REGNO (var->var_part[pos].cur_loc))
		  || rtx_equal_p (loc, var->var_part[pos].cur_loc)))
	    {
	      changed = true;
	      if (var->var_part[pos].loc_chain)
		var->var_part[pos].cur_loc = var->var_part[pos].loc_chain->loc;
	    }
	  else
	    changed = false;

	  if (var->var_part[pos].loc_chain == NULL)
	    {
	      var->n_var_parts--;
	      while (pos < var->n_var_parts)
		{
		  var->var_part[pos] = var->var_part[pos + 1];
		  pos++;
		}
	    }
	  if (changed)
	    variable_was_changed (var, set->vars);
	}
    }
}

/* Emit the NOTE_INSN_VAR_LOCATION for variable *VARP.  DATA contains
   additional parameters: WHERE specifies whether the note shall be emitted
   before of after instruction INSN.  */

static int
emit_note_insn_var_location (void **varp, void *data)
{
  variable var = *(variable *) varp;
  rtx insn = ((emit_note_data *)data)->insn;
  enum emit_note_where where = ((emit_note_data *)data)->where;
  rtx note;
  int i, j, n_var_parts;
  bool complete;
  HOST_WIDE_INT last_limit;
  tree type_size_unit;
  HOST_WIDE_INT offsets[MAX_VAR_PARTS];
  rtx loc[MAX_VAR_PARTS];

  gcc_assert (var->decl);

  complete = true;
  last_limit = 0;
  n_var_parts = 0;
  for (i = 0; i < var->n_var_parts; i++)
    {
      enum machine_mode mode, wider_mode;

      if (last_limit < var->var_part[i].offset)
	{
	  complete = false;
	  break;
	}
      else if (last_limit > var->var_part[i].offset)
	continue;
      offsets[n_var_parts] = var->var_part[i].offset;
      loc[n_var_parts] = var->var_part[i].loc_chain->loc;
      mode = GET_MODE (loc[n_var_parts]);
      last_limit = offsets[n_var_parts] + GET_MODE_SIZE (mode);

      /* Attempt to merge adjacent registers or memory.  */
      wider_mode = GET_MODE_WIDER_MODE (mode);
      for (j = i + 1; j < var->n_var_parts; j++)
	if (last_limit <= var->var_part[j].offset)
	  break;
      if (j < var->n_var_parts
	  && wider_mode != VOIDmode
	  && GET_CODE (loc[n_var_parts])
	     == GET_CODE (var->var_part[j].loc_chain->loc)
	  && mode == GET_MODE (var->var_part[j].loc_chain->loc)
	  && last_limit == var->var_part[j].offset)
	{
	  rtx new_loc = NULL;
	  rtx loc2 = var->var_part[j].loc_chain->loc;

	  if (REG_P (loc[n_var_parts])
	      && hard_regno_nregs[REGNO (loc[n_var_parts])][mode] * 2
		 == hard_regno_nregs[REGNO (loc[n_var_parts])][wider_mode]
	      && REGNO (loc[n_var_parts])
		 + hard_regno_nregs[REGNO (loc[n_var_parts])][mode]
		 == REGNO (loc2))
	    {
	      if (! WORDS_BIG_ENDIAN && ! BYTES_BIG_ENDIAN)
		new_loc = simplify_subreg (wider_mode, loc[n_var_parts],
					   mode, 0);
	      else if (WORDS_BIG_ENDIAN && BYTES_BIG_ENDIAN)
		new_loc = simplify_subreg (wider_mode, loc2, mode, 0);
	      if (new_loc)
		{
		  if (!REG_P (new_loc)
		      || REGNO (new_loc) != REGNO (loc[n_var_parts]))
		    new_loc = NULL;
		  else
		    REG_ATTRS (new_loc) = REG_ATTRS (loc[n_var_parts]);
		}
	    }
	  else if (MEM_P (loc[n_var_parts])
		   && GET_CODE (XEXP (loc2, 0)) == PLUS
		   && GET_CODE (XEXP (XEXP (loc2, 0), 0)) == REG
		   && GET_CODE (XEXP (XEXP (loc2, 0), 1)) == CONST_INT)
	    {
	      if ((GET_CODE (XEXP (loc[n_var_parts], 0)) == REG
		   && rtx_equal_p (XEXP (loc[n_var_parts], 0),
				   XEXP (XEXP (loc2, 0), 0))
		   && INTVAL (XEXP (XEXP (loc2, 0), 1))
		      == GET_MODE_SIZE (mode))
		  || (GET_CODE (XEXP (loc[n_var_parts], 0)) == PLUS
		      && GET_CODE (XEXP (XEXP (loc[n_var_parts], 0), 1))
			 == CONST_INT
		      && rtx_equal_p (XEXP (XEXP (loc[n_var_parts], 0), 0),
				      XEXP (XEXP (loc2, 0), 0))
		      && INTVAL (XEXP (XEXP (loc[n_var_parts], 0), 1))
			 + GET_MODE_SIZE (mode)
			 == INTVAL (XEXP (XEXP (loc2, 0), 1))))
		new_loc = adjust_address_nv (loc[n_var_parts],
					     wider_mode, 0);
	    }

	  if (new_loc)
	    {
	      loc[n_var_parts] = new_loc;
	      mode = wider_mode;
	      last_limit = offsets[n_var_parts] + GET_MODE_SIZE (mode);
	      i = j;
	    }
	}
      ++n_var_parts;
    }
  type_size_unit = TYPE_SIZE_UNIT (TREE_TYPE (var->decl));
  if ((unsigned HOST_WIDE_INT) last_limit < TREE_INT_CST_LOW (type_size_unit))
    complete = false;

  if (where == EMIT_NOTE_AFTER_INSN)
    note = emit_note_after (NOTE_INSN_VAR_LOCATION, insn);
  else
    note = emit_note_before (NOTE_INSN_VAR_LOCATION, insn);

  if (!complete)
    {
      NOTE_VAR_LOCATION (note) = gen_rtx_VAR_LOCATION (VOIDmode, var->decl,
						       NULL_RTX);
    }
  else if (n_var_parts == 1)
    {
      rtx expr_list
	= gen_rtx_EXPR_LIST (VOIDmode, loc[0], GEN_INT (offsets[0]));

      NOTE_VAR_LOCATION (note) = gen_rtx_VAR_LOCATION (VOIDmode, var->decl,
						       expr_list);
    }
  else if (n_var_parts)
    {
      rtx parallel;

      for (i = 0; i < n_var_parts; i++)
	loc[i]
	  = gen_rtx_EXPR_LIST (VOIDmode, loc[i], GEN_INT (offsets[i]));

      parallel = gen_rtx_PARALLEL (VOIDmode,
				   gen_rtvec_v (n_var_parts, loc));
      NOTE_VAR_LOCATION (note) = gen_rtx_VAR_LOCATION (VOIDmode, var->decl,
						       parallel);
    }

  htab_clear_slot (changed_variables, varp);

  /* When there are no location parts the variable has been already
     removed from hash table and a new empty variable was created.
     Free the empty variable.  */
  if (var->n_var_parts == 0)
    {
      pool_free (var_pool, var);
    }

  /* Continue traversing the hash table.  */
  return 1;
}

/* Emit NOTE_INSN_VAR_LOCATION note for each variable from a chain
   CHANGED_VARIABLES and delete this chain.  WHERE specifies whether the notes
   shall be emitted before of after instruction INSN.  */

static void
emit_notes_for_changes (rtx insn, enum emit_note_where where)
{
  emit_note_data data;

  data.insn = insn;
  data.where = where;
  htab_traverse (changed_variables, emit_note_insn_var_location, &data);
}

/* Add variable *SLOT to the chain CHANGED_VARIABLES if it differs from the
   same variable in hash table DATA or is not there at all.  */

static int
emit_notes_for_differences_1 (void **slot, void *data)
{
  htab_t new_vars = (htab_t) data;
  variable old_var, new_var;

  old_var = *(variable *) slot;
  new_var = htab_find_with_hash (new_vars, old_var->decl,
				 VARIABLE_HASH_VAL (old_var->decl));

  if (!new_var)
    {
      /* Variable has disappeared.  */
      variable empty_var;

      empty_var = pool_alloc (var_pool);
      empty_var->decl = old_var->decl;
      empty_var->refcount = 1;
      empty_var->n_var_parts = 0;
      variable_was_changed (empty_var, NULL);
    }
  else if (variable_different_p (old_var, new_var, true))
    {
      variable_was_changed (new_var, NULL);
    }

  /* Continue traversing the hash table.  */
  return 1;
}

/* Add variable *SLOT to the chain CHANGED_VARIABLES if it is not in hash
   table DATA.  */

static int
emit_notes_for_differences_2 (void **slot, void *data)
{
  htab_t old_vars = (htab_t) data;
  variable old_var, new_var;

  new_var = *(variable *) slot;
  old_var = htab_find_with_hash (old_vars, new_var->decl,
				 VARIABLE_HASH_VAL (new_var->decl));
  if (!old_var)
    {
      /* Variable has appeared.  */
      variable_was_changed (new_var, NULL);
    }

  /* Continue traversing the hash table.  */
  return 1;
}

/* Emit notes before INSN for differences between dataflow sets OLD_SET and
   NEW_SET.  */

static void
emit_notes_for_differences (rtx insn, dataflow_set *old_set,
			    dataflow_set *new_set)
{
  htab_traverse (old_set->vars, emit_notes_for_differences_1, new_set->vars);
  htab_traverse (new_set->vars, emit_notes_for_differences_2, old_set->vars);
  emit_notes_for_changes (insn, EMIT_NOTE_BEFORE_INSN);
}

/* Emit the notes for changes of location parts in the basic block BB.  */

static void
emit_notes_in_bb (basic_block bb)
{
  int i;
  dataflow_set set;

  dataflow_set_init (&set, htab_elements (VTI (bb)->in.vars) + 3);
  dataflow_set_copy (&set, &VTI (bb)->in);

  for (i = 0; i < VTI (bb)->n_mos; i++)
    {
      rtx insn = VTI (bb)->mos[i].insn;

      switch (VTI (bb)->mos[i].type)
	{
	  case MO_CALL:
	    {
	      int r;

	      for (r = 0; r < FIRST_PSEUDO_REGISTER; r++)
		if (TEST_HARD_REG_BIT (call_used_reg_set, r))
		  {
		    var_regno_delete (&set, r);
		  }
	      emit_notes_for_changes (insn, EMIT_NOTE_AFTER_INSN);
	    }
	    break;

	  case MO_USE:
	    {
	      rtx loc = VTI (bb)->mos[i].u.loc;

	      if (GET_CODE (loc) == REG)
		var_reg_set (&set, loc);
	      else
		var_mem_set (&set, loc);

	      emit_notes_for_changes (insn, EMIT_NOTE_AFTER_INSN);
	    }
	    break;

	  case MO_SET:
	    {
	      rtx loc = VTI (bb)->mos[i].u.loc;

	      if (REG_P (loc))
		var_reg_delete_and_set (&set, loc, true);
	      else
		var_mem_delete_and_set (&set, loc, true);

	      emit_notes_for_changes (insn, EMIT_NOTE_BEFORE_INSN);
	    }
	    break;

	  case MO_COPY:
	    {
	      rtx loc = VTI (bb)->mos[i].u.loc;

	      if (REG_P (loc))
		var_reg_delete_and_set (&set, loc, false);
	      else
		var_mem_delete_and_set (&set, loc, false);

	      emit_notes_for_changes (insn, EMIT_NOTE_BEFORE_INSN);
	    }
	    break;

	  case MO_USE_NO_VAR:
	    {
	      rtx loc = VTI (bb)->mos[i].u.loc;

	      if (REG_P (loc))
		var_reg_delete (&set, loc, false);
	      else
		var_mem_delete (&set, loc, false);

	      emit_notes_for_changes (insn, EMIT_NOTE_AFTER_INSN);
	    }
	    break;

	  case MO_CLOBBER:
	    {
	      rtx loc = VTI (bb)->mos[i].u.loc;

	      if (REG_P (loc))
		var_reg_delete (&set, loc, true);
	      else
		var_mem_delete (&set, loc, true);

	      emit_notes_for_changes (insn, EMIT_NOTE_BEFORE_INSN);
	    }
	    break;

	  case MO_ADJUST:
	    set.stack_adjust += VTI (bb)->mos[i].u.adjust;
	    break;
	}
    }
  dataflow_set_destroy (&set);
}

/* Emit notes for the whole function.  */

static void
vt_emit_notes (void)
{
  basic_block bb;
  dataflow_set *last_out;
  dataflow_set empty;

  gcc_assert (!htab_elements (changed_variables));

  /* Enable emitting notes by functions (mainly by set_variable_part and
     delete_variable_part).  */
  emit_notes = true;

  dataflow_set_init (&empty, 7);
  last_out = &empty;

  FOR_EACH_BB (bb)
    {
      /* Emit the notes for changes of variable locations between two
	 subsequent basic blocks.  */
      emit_notes_for_differences (BB_HEAD (bb), last_out, &VTI (bb)->in);

      /* Emit the notes for the changes in the basic block itself.  */
      emit_notes_in_bb (bb);

      last_out = &VTI (bb)->out;
    }
  dataflow_set_destroy (&empty);
  emit_notes = false;
}

/* If there is a declaration and offset associated with register/memory RTL
   assign declaration to *DECLP and offset to *OFFSETP, and return true.  */

static bool
vt_get_decl_and_offset (rtx rtl, tree *declp, HOST_WIDE_INT *offsetp)
{
  if (REG_P (rtl))
    {
      if (REG_ATTRS (rtl))
	{
	  *declp = REG_EXPR (rtl);
	  *offsetp = REG_OFFSET (rtl);
	  return true;
	}
    }
  else if (MEM_P (rtl))
    {
      if (MEM_ATTRS (rtl))
	{
	  *declp = MEM_EXPR (rtl);
	  *offsetp = INT_MEM_OFFSET (rtl);
	  return true;
	}
    }
  return false;
}

/* Insert function parameters to IN and OUT sets of ENTRY_BLOCK.  */

static void
vt_add_function_parameters (void)
{
  tree parm;
  
  for (parm = DECL_ARGUMENTS (current_function_decl);
       parm; parm = TREE_CHAIN (parm))
    {
      rtx decl_rtl = DECL_RTL_IF_SET (parm);
      rtx incoming = DECL_INCOMING_RTL (parm);
      tree decl;
      HOST_WIDE_INT offset;
      dataflow_set *out;

      if (TREE_CODE (parm) != PARM_DECL)
	continue;

      if (!DECL_NAME (parm))
	continue;

      if (!decl_rtl || !incoming)
	continue;

      if (GET_MODE (decl_rtl) == BLKmode || GET_MODE (incoming) == BLKmode)
	continue;

      if (!vt_get_decl_and_offset (incoming, &decl, &offset))
	if (!vt_get_decl_and_offset (decl_rtl, &decl, &offset))
	  continue;

      if (!decl)
	continue;

      gcc_assert (parm == decl);

      out = &VTI (ENTRY_BLOCK_PTR)->out;

      if (REG_P (incoming))
	{
	  gcc_assert (REGNO (incoming) < FIRST_PSEUDO_REGISTER);
	  attrs_list_insert (&out->regs[REGNO (incoming)],
			     parm, offset, incoming);
	  set_variable_part (out, incoming, parm, offset);
	}
      else if (MEM_P (incoming))
	set_variable_part (out, incoming, parm, offset);
    }
}

/* Allocate and initialize the data structures for variable tracking
   and parse the RTL to get the micro operations.  */

static void
vt_initialize (void)
{
  basic_block bb;

  alloc_aux_for_blocks (sizeof (struct variable_tracking_info_def));

  FOR_EACH_BB (bb)
    {
      rtx insn;
      HOST_WIDE_INT pre, post = 0;

      /* Count the number of micro operations.  */
      VTI (bb)->n_mos = 0;
      for (insn = BB_HEAD (bb); insn != NEXT_INSN (BB_END (bb));
	   insn = NEXT_INSN (insn))
	{
	  if (INSN_P (insn))
	    {
	      if (!frame_pointer_needed)
		{
		  insn_stack_adjust_offset_pre_post (insn, &pre, &post);
		  if (pre)
		    VTI (bb)->n_mos++;
		  if (post)
		    VTI (bb)->n_mos++;
		}
	      note_uses (&PATTERN (insn), count_uses_1, insn);
	      note_stores (PATTERN (insn), count_stores, insn);
	      if (CALL_P (insn))
		VTI (bb)->n_mos++;
	    }
	}

      /* Add the micro-operations to the array.  */
      VTI (bb)->mos = XNEWVEC (micro_operation, VTI (bb)->n_mos);
      VTI (bb)->n_mos = 0;
      for (insn = BB_HEAD (bb); insn != NEXT_INSN (BB_END (bb));
	   insn = NEXT_INSN (insn))
	{
	  if (INSN_P (insn))
	    {
	      int n1, n2;

	      if (!frame_pointer_needed)
		{
		  insn_stack_adjust_offset_pre_post (insn, &pre, &post);
		  if (pre)
		    {
		      micro_operation *mo = VTI (bb)->mos + VTI (bb)->n_mos++;

		      mo->type = MO_ADJUST;
		      mo->u.adjust = pre;
		      mo->insn = insn;
		    }
		}

	      n1 = VTI (bb)->n_mos;
	      note_uses (&PATTERN (insn), add_uses_1, insn);
	      n2 = VTI (bb)->n_mos - 1;

	      /* Order the MO_USEs to be before MO_USE_NO_VARs.  */
	      while (n1 < n2)
		{
		  while (n1 < n2 && VTI (bb)->mos[n1].type == MO_USE)
		    n1++;
		  while (n1 < n2 && VTI (bb)->mos[n2].type == MO_USE_NO_VAR)
		    n2--;
		  if (n1 < n2)
		    {
		      micro_operation sw;

		      sw = VTI (bb)->mos[n1];
		      VTI (bb)->mos[n1] = VTI (bb)->mos[n2];
		      VTI (bb)->mos[n2] = sw;
		    }
		}

	      if (CALL_P (insn))
		{
		  micro_operation *mo = VTI (bb)->mos + VTI (bb)->n_mos++;

		  mo->type = MO_CALL;
		  mo->insn = insn;
		}

	      n1 = VTI (bb)->n_mos;
	      /* This will record NEXT_INSN (insn), such that we can
		 insert notes before it without worrying about any
		 notes that MO_USEs might emit after the insn.  */
	      note_stores (PATTERN (insn), add_stores, insn);
	      n2 = VTI (bb)->n_mos - 1;

	      /* Order the MO_CLOBBERs to be before MO_SETs.  */
	      while (n1 < n2)
		{
		  while (n1 < n2 && VTI (bb)->mos[n1].type == MO_CLOBBER)
		    n1++;
		  while (n1 < n2 && (VTI (bb)->mos[n2].type == MO_SET
				     || VTI (bb)->mos[n2].type == MO_COPY))
		    n2--;
		  if (n1 < n2)
		    {
		      micro_operation sw;

		      sw = VTI (bb)->mos[n1];
		      VTI (bb)->mos[n1] = VTI (bb)->mos[n2];
		      VTI (bb)->mos[n2] = sw;
		    }
		}

	      if (!frame_pointer_needed && post)
		{
		  micro_operation *mo = VTI (bb)->mos + VTI (bb)->n_mos++;

		  mo->type = MO_ADJUST;
		  mo->u.adjust = post;
		  mo->insn = insn;
		}
	    }
	}
    }

  /* Init the IN and OUT sets.  */
  FOR_ALL_BB (bb)
    {
      VTI (bb)->visited = false;
      dataflow_set_init (&VTI (bb)->in, 7);
      dataflow_set_init (&VTI (bb)->out, 7);
    }

  attrs_pool = create_alloc_pool ("attrs_def pool",
				  sizeof (struct attrs_def), 1024);
  var_pool = create_alloc_pool ("variable_def pool",
				sizeof (struct variable_def), 64);
  loc_chain_pool = create_alloc_pool ("location_chain_def pool",
				      sizeof (struct location_chain_def),
				      1024);
  changed_variables = htab_create (10, variable_htab_hash, variable_htab_eq,
				   NULL);
  vt_add_function_parameters ();
}

/* Free the data structures needed for variable tracking.  */

static void
vt_finalize (void)
{
  basic_block bb;

  FOR_EACH_BB (bb)
    {
      free (VTI (bb)->mos);
    }

  FOR_ALL_BB (bb)
    {
      dataflow_set_destroy (&VTI (bb)->in);
      dataflow_set_destroy (&VTI (bb)->out);
    }
  free_aux_for_blocks ();
  free_alloc_pool (attrs_pool);
  free_alloc_pool (var_pool);
  free_alloc_pool (loc_chain_pool);
  htab_delete (changed_variables);
}

/* The entry point to variable tracking pass.  */

unsigned int
variable_tracking_main (void)
{
  if (n_basic_blocks > 500 && n_edges / n_basic_blocks >= 20)
    return 0;

  mark_dfs_back_edges ();
  vt_initialize ();
  if (!frame_pointer_needed)
    {
      if (!vt_stack_adjustments ())
	{
	  vt_finalize ();
	  return 0;
	}
    }

  vt_find_locations ();
  vt_emit_notes ();

  if (dump_file && (dump_flags & TDF_DETAILS))
    {
      dump_dataflow_sets ();
      dump_flow_info (dump_file, dump_flags);
    }

  vt_finalize ();
  return 0;
}

static bool
gate_handle_var_tracking (void)
{
  return (flag_var_tracking);
}



struct tree_opt_pass pass_variable_tracking =
{
  "vartrack",                           /* name */
  gate_handle_var_tracking,             /* gate */
  variable_tracking_main,               /* execute */
  NULL,                                 /* sub */
  NULL,                                 /* next */
  0,                                    /* static_pass_number */
  TV_VAR_TRACKING,                      /* tv_id */
  0,                                    /* properties_required */
  0,                                    /* properties_provided */
  0,                                    /* properties_destroyed */
  0,                                    /* todo_flags_start */
  TODO_dump_func,                       /* todo_flags_finish */
  'V'                                   /* letter */
};

OpenPOWER on IntegriCloud