aboutsummaryrefslogtreecommitdiffstats
path: root/docs/LangRef.html
blob: da7c7e1dea705abe538b0a5179ebfaa3c471bbf5 (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
3036
3037
3038
3039
3040
3041
3042
3043
3044
3045
3046
3047
3048
3049
3050
3051
3052
3053
3054
3055
3056
3057
3058
3059
3060
3061
3062
3063
3064
3065
3066
3067
3068
3069
3070
3071
3072
3073
3074
3075
3076
3077
3078
3079
3080
3081
3082
3083
3084
3085
3086
3087
3088
3089
3090
3091
3092
3093
3094
3095
3096
3097
3098
3099
3100
3101
3102
3103
3104
3105
3106
3107
3108
3109
3110
3111
3112
3113
3114
3115
3116
3117
3118
3119
3120
3121
3122
3123
3124
3125
3126
3127
3128
3129
3130
3131
3132
3133
3134
3135
3136
3137
3138
3139
3140
3141
3142
3143
3144
3145
3146
3147
3148
3149
3150
3151
3152
3153
3154
3155
3156
3157
3158
3159
3160
3161
3162
3163
3164
3165
3166
3167
3168
3169
3170
3171
3172
3173
3174
3175
3176
3177
3178
3179
3180
3181
3182
3183
3184
3185
3186
3187
3188
3189
3190
3191
3192
3193
3194
3195
3196
3197
3198
3199
3200
3201
3202
3203
3204
3205
3206
3207
3208
3209
3210
3211
3212
3213
3214
3215
3216
3217
3218
3219
3220
3221
3222
3223
3224
3225
3226
3227
3228
3229
3230
3231
3232
3233
3234
3235
3236
3237
3238
3239
3240
3241
3242
3243
3244
3245
3246
3247
3248
3249
3250
3251
3252
3253
3254
3255
3256
3257
3258
3259
3260
3261
3262
3263
3264
3265
3266
3267
3268
3269
3270
3271
3272
3273
3274
3275
3276
3277
3278
3279
3280
3281
3282
3283
3284
3285
3286
3287
3288
3289
3290
3291
3292
3293
3294
3295
3296
3297
3298
3299
3300
3301
3302
3303
3304
3305
3306
3307
3308
3309
3310
3311
3312
3313
3314
3315
3316
3317
3318
3319
3320
3321
3322
3323
3324
3325
3326
3327
3328
3329
3330
3331
3332
3333
3334
3335
3336
3337
3338
3339
3340
3341
3342
3343
3344
3345
3346
3347
3348
3349
3350
3351
3352
3353
3354
3355
3356
3357
3358
3359
3360
3361
3362
3363
3364
3365
3366
3367
3368
3369
3370
3371
3372
3373
3374
3375
3376
3377
3378
3379
3380
3381
3382
3383
3384
3385
3386
3387
3388
3389
3390
3391
3392
3393
3394
3395
3396
3397
3398
3399
3400
3401
3402
3403
3404
3405
3406
3407
3408
3409
3410
3411
3412
3413
3414
3415
3416
3417
3418
3419
3420
3421
3422
3423
3424
3425
3426
3427
3428
3429
3430
3431
3432
3433
3434
3435
3436
3437
3438
3439
3440
3441
3442
3443
3444
3445
3446
3447
3448
3449
3450
3451
3452
3453
3454
3455
3456
3457
3458
3459
3460
3461
3462
3463
3464
3465
3466
3467
3468
3469
3470
3471
3472
3473
3474
3475
3476
3477
3478
3479
3480
3481
3482
3483
3484
3485
3486
3487
3488
3489
3490
3491
3492
3493
3494
3495
3496
3497
3498
3499
3500
3501
3502
3503
3504
3505
3506
3507
3508
3509
3510
3511
3512
3513
3514
3515
3516
3517
3518
3519
3520
3521
3522
3523
3524
3525
3526
3527
3528
3529
3530
3531
3532
3533
3534
3535
3536
3537
3538
3539
3540
3541
3542
3543
3544
3545
3546
3547
3548
3549
3550
3551
3552
3553
3554
3555
3556
3557
3558
3559
3560
3561
3562
3563
3564
3565
3566
3567
3568
3569
3570
3571
3572
3573
3574
3575
3576
3577
3578
3579
3580
3581
3582
3583
3584
3585
3586
3587
3588
3589
3590
3591
3592
3593
3594
3595
3596
3597
3598
3599
3600
3601
3602
3603
3604
3605
3606
3607
3608
3609
3610
3611
3612
3613
3614
3615
3616
3617
3618
3619
3620
3621
3622
3623
3624
3625
3626
3627
3628
3629
3630
3631
3632
3633
3634
3635
3636
3637
3638
3639
3640
3641
3642
3643
3644
3645
3646
3647
3648
3649
3650
3651
3652
3653
3654
3655
3656
3657
3658
3659
3660
3661
3662
3663
3664
3665
3666
3667
3668
3669
3670
3671
3672
3673
3674
3675
3676
3677
3678
3679
3680
3681
3682
3683
3684
3685
3686
3687
3688
3689
3690
3691
3692
3693
3694
3695
3696
3697
3698
3699
3700
3701
3702
3703
3704
3705
3706
3707
3708
3709
3710
3711
3712
3713
3714
3715
3716
3717
3718
3719
3720
3721
3722
3723
3724
3725
3726
3727
3728
3729
3730
3731
3732
3733
3734
3735
3736
3737
3738
3739
3740
3741
3742
3743
3744
3745
3746
3747
3748
3749
3750
3751
3752
3753
3754
3755
3756
3757
3758
3759
3760
3761
3762
3763
3764
3765
3766
3767
3768
3769
3770
3771
3772
3773
3774
3775
3776
3777
3778
3779
3780
3781
3782
3783
3784
3785
3786
3787
3788
3789
3790
3791
3792
3793
3794
3795
3796
3797
3798
3799
3800
3801
3802
3803
3804
3805
3806
3807
3808
3809
3810
3811
3812
3813
3814
3815
3816
3817
3818
3819
3820
3821
3822
3823
3824
3825
3826
3827
3828
3829
3830
3831
3832
3833
3834
3835
3836
3837
3838
3839
3840
3841
3842
3843
3844
3845
3846
3847
3848
3849
3850
3851
3852
3853
3854
3855
3856
3857
3858
3859
3860
3861
3862
3863
3864
3865
3866
3867
3868
3869
3870
3871
3872
3873
3874
3875
3876
3877
3878
3879
3880
3881
3882
3883
3884
3885
3886
3887
3888
3889
3890
3891
3892
3893
3894
3895
3896
3897
3898
3899
3900
3901
3902
3903
3904
3905
3906
3907
3908
3909
3910
3911
3912
3913
3914
3915
3916
3917
3918
3919
3920
3921
3922
3923
3924
3925
3926
3927
3928
3929
3930
3931
3932
3933
3934
3935
3936
3937
3938
3939
3940
3941
3942
3943
3944
3945
3946
3947
3948
3949
3950
3951
3952
3953
3954
3955
3956
3957
3958
3959
3960
3961
3962
3963
3964
3965
3966
3967
3968
3969
3970
3971
3972
3973
3974
3975
3976
3977
3978
3979
3980
3981
3982
3983
3984
3985
3986
3987
3988
3989
3990
3991
3992
3993
3994
3995
3996
3997
3998
3999
4000
4001
4002
4003
4004
4005
4006
4007
4008
4009
4010
4011
4012
4013
4014
4015
4016
4017
4018
4019
4020
4021
4022
4023
4024
4025
4026
4027
4028
4029
4030
4031
4032
4033
4034
4035
4036
4037
4038
4039
4040
4041
4042
4043
4044
4045
4046
4047
4048
4049
4050
4051
4052
4053
4054
4055
4056
4057
4058
4059
4060
4061
4062
4063
4064
4065
4066
4067
4068
4069
4070
4071
4072
4073
4074
4075
4076
4077
4078
4079
4080
4081
4082
4083
4084
4085
4086
4087
4088
4089
4090
4091
4092
4093
4094
4095
4096
4097
4098
4099
4100
4101
4102
4103
4104
4105
4106
4107
4108
4109
4110
4111
4112
4113
4114
4115
4116
4117
4118
4119
4120
4121
4122
4123
4124
4125
4126
4127
4128
4129
4130
4131
4132
4133
4134
4135
4136
4137
4138
4139
4140
4141
4142
4143
4144
4145
4146
4147
4148
4149
4150
4151
4152
4153
4154
4155
4156
4157
4158
4159
4160
4161
4162
4163
4164
4165
4166
4167
4168
4169
4170
4171
4172
4173
4174
4175
4176
4177
4178
4179
4180
4181
4182
4183
4184
4185
4186
4187
4188
4189
4190
4191
4192
4193
4194
4195
4196
4197
4198
4199
4200
4201
4202
4203
4204
4205
4206
4207
4208
4209
4210
4211
4212
4213
4214
4215
4216
4217
4218
4219
4220
4221
4222
4223
4224
4225
4226
4227
4228
4229
4230
4231
4232
4233
4234
4235
4236
4237
4238
4239
4240
4241
4242
4243
4244
4245
4246
4247
4248
4249
4250
4251
4252
4253
4254
4255
4256
4257
4258
4259
4260
4261
4262
4263
4264
4265
4266
4267
4268
4269
4270
4271
4272
4273
4274
4275
4276
4277
4278
4279
4280
4281
4282
4283
4284
4285
4286
4287
4288
4289
4290
4291
4292
4293
4294
4295
4296
4297
4298
4299
4300
4301
4302
4303
4304
4305
4306
4307
4308
4309
4310
4311
4312
4313
4314
4315
4316
4317
4318
4319
4320
4321
4322
4323
4324
4325
4326
4327
4328
4329
4330
4331
4332
4333
4334
4335
4336
4337
4338
4339
4340
4341
4342
4343
4344
4345
4346
4347
4348
4349
4350
4351
4352
4353
4354
4355
4356
4357
4358
4359
4360
4361
4362
4363
4364
4365
4366
4367
4368
4369
4370
4371
4372
4373
4374
4375
4376
4377
4378
4379
4380
4381
4382
4383
4384
4385
4386
4387
4388
4389
4390
4391
4392
4393
4394
4395
4396
4397
4398
4399
4400
4401
4402
4403
4404
4405
4406
4407
4408
4409
4410
4411
4412
4413
4414
4415
4416
4417
4418
4419
4420
4421
4422
4423
4424
4425
4426
4427
4428
4429
4430
4431
4432
4433
4434
4435
4436
4437
4438
4439
4440
4441
4442
4443
4444
4445
4446
4447
4448
4449
4450
4451
4452
4453
4454
4455
4456
4457
4458
4459
4460
4461
4462
4463
4464
4465
4466
4467
4468
4469
4470
4471
4472
4473
4474
4475
4476
4477
4478
4479
4480
4481
4482
4483
4484
4485
4486
4487
4488
4489
4490
4491
4492
4493
4494
4495
4496
4497
4498
4499
4500
4501
4502
4503
4504
4505
4506
4507
4508
4509
4510
4511
4512
4513
4514
4515
4516
4517
4518
4519
4520
4521
4522
4523
4524
4525
4526
4527
4528
4529
4530
4531
4532
4533
4534
4535
4536
4537
4538
4539
4540
4541
4542
4543
4544
4545
4546
4547
4548
4549
4550
4551
4552
4553
4554
4555
4556
4557
4558
4559
4560
4561
4562
4563
4564
4565
4566
4567
4568
4569
4570
4571
4572
4573
4574
4575
4576
4577
4578
4579
4580
4581
4582
4583
4584
4585
4586
4587
4588
4589
4590
4591
4592
4593
4594
4595
4596
4597
4598
4599
4600
4601
4602
4603
4604
4605
4606
4607
4608
4609
4610
4611
4612
4613
4614
4615
4616
4617
4618
4619
4620
4621
4622
4623
4624
4625
4626
4627
4628
4629
4630
4631
4632
4633
4634
4635
4636
4637
4638
4639
4640
4641
4642
4643
4644
4645
4646
4647
4648
4649
4650
4651
4652
4653
4654
4655
4656
4657
4658
4659
4660
4661
4662
4663
4664
4665
4666
4667
4668
4669
4670
4671
4672
4673
4674
4675
4676
4677
4678
4679
4680
4681
4682
4683
4684
4685
4686
4687
4688
4689
4690
4691
4692
4693
4694
4695
4696
4697
4698
4699
4700
4701
4702
4703
4704
4705
4706
4707
4708
4709
4710
4711
4712
4713
4714
4715
4716
4717
4718
4719
4720
4721
4722
4723
4724
4725
4726
4727
4728
4729
4730
4731
4732
4733
4734
4735
4736
4737
4738
4739
4740
4741
4742
4743
4744
4745
4746
4747
4748
4749
4750
4751
4752
4753
4754
4755
4756
4757
4758
4759
4760
4761
4762
4763
4764
4765
4766
4767
4768
4769
4770
4771
4772
4773
4774
4775
4776
4777
4778
4779
4780
4781
4782
4783
4784
4785
4786
4787
4788
4789
4790
4791
4792
4793
4794
4795
4796
4797
4798
4799
4800
4801
4802
4803
4804
4805
4806
4807
4808
4809
4810
4811
4812
4813
4814
4815
4816
4817
4818
4819
4820
4821
4822
4823
4824
4825
4826
4827
4828
4829
4830
4831
4832
4833
4834
4835
4836
4837
4838
4839
4840
4841
4842
4843
4844
4845
4846
4847
4848
4849
4850
4851
4852
4853
4854
4855
4856
4857
4858
4859
4860
4861
4862
4863
4864
4865
4866
4867
4868
4869
4870
4871
4872
4873
4874
4875
4876
4877
4878
4879
4880
4881
4882
4883
4884
4885
4886
4887
4888
4889
4890
4891
4892
4893
4894
4895
4896
4897
4898
4899
4900
4901
4902
4903
4904
4905
4906
4907
4908
4909
4910
4911
4912
4913
4914
4915
4916
4917
4918
4919
4920
4921
4922
4923
4924
4925
4926
4927
4928
4929
4930
4931
4932
4933
4934
4935
4936
4937
4938
4939
4940
4941
4942
4943
4944
4945
4946
4947
4948
4949
4950
4951
4952
4953
4954
4955
4956
4957
4958
4959
4960
4961
4962
4963
4964
4965
4966
4967
4968
4969
4970
4971
4972
4973
4974
4975
4976
4977
4978
4979
4980
4981
4982
4983
4984
4985
4986
4987
4988
4989
4990
4991
4992
4993
4994
4995
4996
4997
4998
4999
5000
5001
5002
5003
5004
5005
5006
5007
5008
5009
5010
5011
5012
5013
5014
5015
5016
5017
5018
5019
5020
5021
5022
5023
5024
5025
5026
5027
5028
5029
5030
5031
5032
5033
5034
5035
5036
5037
5038
5039
5040
5041
5042
5043
5044
5045
5046
5047
5048
5049
5050
5051
5052
5053
5054
5055
5056
5057
5058
5059
5060
5061
5062
5063
5064
5065
5066
5067
5068
5069
5070
5071
5072
5073
5074
5075
5076
5077
5078
5079
5080
5081
5082
5083
5084
5085
5086
5087
5088
5089
5090
5091
5092
5093
5094
5095
5096
5097
5098
5099
5100
5101
5102
5103
5104
5105
5106
5107
5108
5109
5110
5111
5112
5113
5114
5115
5116
5117
5118
5119
5120
5121
5122
5123
5124
5125
5126
5127
5128
5129
5130
5131
5132
5133
5134
5135
5136
5137
5138
5139
5140
5141
5142
5143
5144
5145
5146
5147
5148
5149
5150
5151
5152
5153
5154
5155
5156
5157
5158
5159
5160
5161
5162
5163
5164
5165
5166
5167
5168
5169
5170
5171
5172
5173
5174
5175
5176
5177
5178
5179
5180
5181
5182
5183
5184
5185
5186
5187

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
                      "http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
  <title>LLVM Assembly Language Reference Manual</title>
  <meta http-equiv="Content-Type" content="text/html; charset=utf-8">
  <meta name="author" content="Chris Lattner">
  <meta name="description" 
  content="LLVM Assembly Language Reference Manual.">
  <link rel="stylesheet" href="llvm.css" type="text/css">
</head>

<body>

<div class="doc_title"> LLVM Language Reference Manual </div>
<ol>
  <li><a href="#abstract">Abstract</a></li>
  <li><a href="#introduction">Introduction</a></li>
  <li><a href="#identifiers">Identifiers</a></li>
  <li><a href="#highlevel">High Level Structure</a>
    <ol>
      <li><a href="#modulestructure">Module Structure</a></li>
      <li><a href="#linkage">Linkage Types</a></li>
      <li><a href="#callingconv">Calling Conventions</a></li>
      <li><a href="#globalvars">Global Variables</a></li>
      <li><a href="#functionstructure">Functions</a></li>
      <li><a href="#aliasstructure">Aliases</a>
      <li><a href="#paramattrs">Parameter Attributes</a></li>
      <li><a href="#moduleasm">Module-Level Inline Assembly</a></li>
      <li><a href="#datalayout">Data Layout</a></li>
    </ol>
  </li>
  <li><a href="#typesystem">Type System</a>
    <ol>
      <li><a href="#t_primitive">Primitive Types</a>    
        <ol>
          <li><a href="#t_classifications">Type Classifications</a></li>
        </ol>
      </li>
      <li><a href="#t_derived">Derived Types</a>
        <ol>
          <li><a href="#t_array">Array Type</a></li>
          <li><a href="#t_function">Function Type</a></li>
          <li><a href="#t_pointer">Pointer Type</a></li>
          <li><a href="#t_struct">Structure Type</a></li>
          <li><a href="#t_pstruct">Packed Structure Type</a></li>
          <li><a href="#t_vector">Vector Type</a></li>
          <li><a href="#t_opaque">Opaque Type</a></li>
        </ol>
      </li>
    </ol>
  </li>
  <li><a href="#constants">Constants</a>
    <ol>
      <li><a href="#simpleconstants">Simple Constants</a>
      <li><a href="#aggregateconstants">Aggregate Constants</a>
      <li><a href="#globalconstants">Global Variable and Function Addresses</a>
      <li><a href="#undefvalues">Undefined Values</a>
      <li><a href="#constantexprs">Constant Expressions</a>
    </ol>
  </li>
  <li><a href="#othervalues">Other Values</a>
    <ol>
      <li><a href="#inlineasm">Inline Assembler Expressions</a>
    </ol>
  </li>
  <li><a href="#instref">Instruction Reference</a>
    <ol>
      <li><a href="#terminators">Terminator Instructions</a>
        <ol>
          <li><a href="#i_ret">'<tt>ret</tt>' Instruction</a></li>
          <li><a href="#i_br">'<tt>br</tt>' Instruction</a></li>
          <li><a href="#i_switch">'<tt>switch</tt>' Instruction</a></li>
          <li><a href="#i_invoke">'<tt>invoke</tt>' Instruction</a></li>
          <li><a href="#i_unwind">'<tt>unwind</tt>'  Instruction</a></li>
          <li><a href="#i_unreachable">'<tt>unreachable</tt>' Instruction</a></li>
        </ol>
      </li>
      <li><a href="#binaryops">Binary Operations</a>
        <ol>
          <li><a href="#i_add">'<tt>add</tt>' Instruction</a></li>
          <li><a href="#i_sub">'<tt>sub</tt>' Instruction</a></li>
          <li><a href="#i_mul">'<tt>mul</tt>' Instruction</a></li>
          <li><a href="#i_udiv">'<tt>udiv</tt>' Instruction</a></li>
          <li><a href="#i_sdiv">'<tt>sdiv</tt>' Instruction</a></li>
          <li><a href="#i_fdiv">'<tt>fdiv</tt>' Instruction</a></li>
          <li><a href="#i_urem">'<tt>urem</tt>' Instruction</a></li>
          <li><a href="#i_srem">'<tt>srem</tt>' Instruction</a></li>
          <li><a href="#i_frem">'<tt>frem</tt>' Instruction</a></li>
        </ol>
      </li>
      <li><a href="#bitwiseops">Bitwise Binary Operations</a>
        <ol>
          <li><a href="#i_shl">'<tt>shl</tt>' Instruction</a></li>
          <li><a href="#i_lshr">'<tt>lshr</tt>' Instruction</a></li>
          <li><a href="#i_ashr">'<tt>ashr</tt>' Instruction</a></li>
          <li><a href="#i_and">'<tt>and</tt>' Instruction</a></li>
          <li><a href="#i_or">'<tt>or</tt>'  Instruction</a></li>
          <li><a href="#i_xor">'<tt>xor</tt>' Instruction</a></li>
        </ol>
      </li>
      <li><a href="#vectorops">Vector Operations</a>
        <ol>
          <li><a href="#i_extractelement">'<tt>extractelement</tt>' Instruction</a></li>
          <li><a href="#i_insertelement">'<tt>insertelement</tt>' Instruction</a></li>
          <li><a href="#i_shufflevector">'<tt>shufflevector</tt>' Instruction</a></li>
        </ol>
      </li>
      <li><a href="#memoryops">Memory Access and Addressing Operations</a>
        <ol>
          <li><a href="#i_malloc">'<tt>malloc</tt>'   Instruction</a></li>
          <li><a href="#i_free">'<tt>free</tt>'     Instruction</a></li>
          <li><a href="#i_alloca">'<tt>alloca</tt>'   Instruction</a></li>
         <li><a href="#i_load">'<tt>load</tt>'     Instruction</a></li>
         <li><a href="#i_store">'<tt>store</tt>'    Instruction</a></li>
         <li><a href="#i_getelementptr">'<tt>getelementptr</tt>' Instruction</a></li>
        </ol>
      </li>
      <li><a href="#convertops">Conversion Operations</a>
        <ol>
          <li><a href="#i_trunc">'<tt>trunc .. to</tt>' Instruction</a></li>
          <li><a href="#i_zext">'<tt>zext .. to</tt>' Instruction</a></li>
          <li><a href="#i_sext">'<tt>sext .. to</tt>' Instruction</a></li>
          <li><a href="#i_fptrunc">'<tt>fptrunc .. to</tt>' Instruction</a></li>
          <li><a href="#i_fpext">'<tt>fpext .. to</tt>' Instruction</a></li>
          <li><a href="#i_fptoui">'<tt>fptoui .. to</tt>' Instruction</a></li>
          <li><a href="#i_fptosi">'<tt>fptosi .. to</tt>' Instruction</a></li>
          <li><a href="#i_uitofp">'<tt>uitofp .. to</tt>' Instruction</a></li>
          <li><a href="#i_sitofp">'<tt>sitofp .. to</tt>' Instruction</a></li>
          <li><a href="#i_ptrtoint">'<tt>ptrtoint .. to</tt>' Instruction</a></li>
          <li><a href="#i_inttoptr">'<tt>inttoptr .. to</tt>' Instruction</a></li>
          <li><a href="#i_bitcast">'<tt>bitcast .. to</tt>' Instruction</a></li>
        </ol>
      <li><a href="#otherops">Other Operations</a>
        <ol>
          <li><a href="#i_icmp">'<tt>icmp</tt>' Instruction</a></li>
          <li><a href="#i_fcmp">'<tt>fcmp</tt>' Instruction</a></li>
          <li><a href="#i_phi">'<tt>phi</tt>'   Instruction</a></li>
          <li><a href="#i_select">'<tt>select</tt>' Instruction</a></li>
          <li><a href="#i_call">'<tt>call</tt>'  Instruction</a></li>
          <li><a href="#i_va_arg">'<tt>va_arg</tt>'  Instruction</a></li>
        </ol>
      </li>
    </ol>
  </li>
  <li><a href="#intrinsics">Intrinsic Functions</a>
    <ol>
      <li><a href="#int_varargs">Variable Argument Handling Intrinsics</a>
        <ol>
          <li><a href="#int_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a></li>
          <li><a href="#int_va_end">'<tt>llvm.va_end</tt>'   Intrinsic</a></li>
          <li><a href="#int_va_copy">'<tt>llvm.va_copy</tt>'  Intrinsic</a></li>
        </ol>
      </li>
      <li><a href="#int_gc">Accurate Garbage Collection Intrinsics</a>
        <ol>
          <li><a href="#int_gcroot">'<tt>llvm.gcroot</tt>' Intrinsic</a></li>
          <li><a href="#int_gcread">'<tt>llvm.gcread</tt>' Intrinsic</a></li>
          <li><a href="#int_gcwrite">'<tt>llvm.gcwrite</tt>' Intrinsic</a></li>
        </ol>
      </li>
      <li><a href="#int_codegen">Code Generator Intrinsics</a>
        <ol>
          <li><a href="#int_returnaddress">'<tt>llvm.returnaddress</tt>' Intrinsic</a></li>
          <li><a href="#int_frameaddress">'<tt>llvm.frameaddress</tt>'   Intrinsic</a></li>
          <li><a href="#int_stacksave">'<tt>llvm.stacksave</tt>' Intrinsic</a></li>
          <li><a href="#int_stackrestore">'<tt>llvm.stackrestore</tt>' Intrinsic</a></li>
          <li><a href="#int_prefetch">'<tt>llvm.prefetch</tt>' Intrinsic</a></li>
          <li><a href="#int_pcmarker">'<tt>llvm.pcmarker</tt>' Intrinsic</a></li>
          <li><a href="#int_readcyclecounter"><tt>llvm.readcyclecounter</tt>' Intrinsic</a></li>
        </ol>
      </li>
      <li><a href="#int_libc">Standard C Library Intrinsics</a>
        <ol>
          <li><a href="#int_memcpy">'<tt>llvm.memcpy.*</tt>' Intrinsic</a></li>
          <li><a href="#int_memmove">'<tt>llvm.memmove.*</tt>' Intrinsic</a></li>
          <li><a href="#int_memset">'<tt>llvm.memset.*</tt>' Intrinsic</a></li>
          <li><a href="#int_sqrt">'<tt>llvm.sqrt.*</tt>' Intrinsic</a></li>
          <li><a href="#int_powi">'<tt>llvm.powi.*</tt>' Intrinsic</a></li>
        </ol>
      </li>
      <li><a href="#int_manip">Bit Manipulation Intrinsics</a>
        <ol>
          <li><a href="#int_bswap">'<tt>llvm.bswap.*</tt>' Intrinsics</a></li>
          <li><a href="#int_ctpop">'<tt>llvm.ctpop.*</tt>' Intrinsic </a></li>
          <li><a href="#int_ctlz">'<tt>llvm.ctlz.*</tt>' Intrinsic </a></li>
          <li><a href="#int_cttz">'<tt>llvm.cttz.*</tt>' Intrinsic </a></li>
          <li><a href="#int_part_select">'<tt>llvm.part.select.*</tt>' Intrinsic </a></li>
          <li><a href="#int_part_set">'<tt>llvm.part.set.*</tt>' Intrinsic </a></li>
        </ol>
      </li>
      <li><a href="#int_debugger">Debugger intrinsics</a></li>
      <li><a href="#int_eh">Exception Handling intrinsics</a></li>
      <li><a href="#int_atomics">Atomic Operations and Synchronization Intrinsics</a>
        <ol>
          <li><a href="#int_lcs">'<tt>llvm.atomic.lcs.*</tt>' Intrinsic</a></li>
          <li><a href="#int_ls">'<tt>llvm.atomic.ls.*</tt>' Intrinsic</a></li>
          <li><a href="#int_las">'<tt>llvm.atomic.las.*</tt>' Intrinsic</a></li>
          <li><a href="#int_lss">'<tt>llvm.atomic.lss.*</tt>' Intrinsic</a></li>
          <li><a href="#int_memory_barrier">'<tt>llvm.memory.barrier</tt>' Intrinsic</a></li>
        </ol>
      </li>
      <li><a href="#int_general">General intrinsics</a></li>
        <ol>
          <li><a href="#int_var_annotation">'<tt>llvm.var.annotation</tt>' 
                                                              Intrinsic</a></li>
          </ol>
      </li>
    </ol>
  </li>
</ol>

<div class="doc_author">
  <p>Written by <a href="mailto:sabre@nondot.org">Chris Lattner</a>
            and <a href="mailto:vadve@cs.uiuc.edu">Vikram Adve</a></p>
</div>

<!-- *********************************************************************** -->
<div class="doc_section"> <a name="abstract">Abstract </a></div>
<!-- *********************************************************************** -->

<div class="doc_text">
<p>This document is a reference manual for the LLVM assembly language. 
LLVM is an SSA based representation that provides type safety,
low-level operations, flexibility, and the capability of representing
'all' high-level languages cleanly.  It is the common code
representation used throughout all phases of the LLVM compilation
strategy.</p>
</div>

<!-- *********************************************************************** -->
<div class="doc_section"> <a name="introduction">Introduction</a> </div>
<!-- *********************************************************************** -->

<div class="doc_text">

<p>The LLVM code representation is designed to be used in three
different forms: as an in-memory compiler IR, as an on-disk bitcode
representation (suitable for fast loading by a Just-In-Time compiler),
and as a human readable assembly language representation.  This allows
LLVM to provide a powerful intermediate representation for efficient
compiler transformations and analysis, while providing a natural means
to debug and visualize the transformations.  The three different forms
of LLVM are all equivalent.  This document describes the human readable
representation and notation.</p>

<p>The LLVM representation aims to be light-weight and low-level
while being expressive, typed, and extensible at the same time.  It
aims to be a "universal IR" of sorts, by being at a low enough level
that high-level ideas may be cleanly mapped to it (similar to how
microprocessors are "universal IR's", allowing many source languages to
be mapped to them).  By providing type information, LLVM can be used as
the target of optimizations: for example, through pointer analysis, it
can be proven that a C automatic variable is never accessed outside of
the current function... allowing it to be promoted to a simple SSA
value instead of a memory location.</p>

</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection"> <a name="wellformed">Well-Formedness</a> </div>

<div class="doc_text">

<p>It is important to note that this document describes 'well formed'
LLVM assembly language.  There is a difference between what the parser
accepts and what is considered 'well formed'.  For example, the
following instruction is syntactically okay, but not well formed:</p>

<div class="doc_code">
<pre>
%x = <a href="#i_add">add</a> i32 1, %x
</pre>
</div>

<p>...because the definition of <tt>%x</tt> does not dominate all of
its uses. The LLVM infrastructure provides a verification pass that may
be used to verify that an LLVM module is well formed.  This pass is
automatically run by the parser after parsing input assembly and by
the optimizer before it outputs bitcode.  The violations pointed out
by the verifier pass indicate bugs in transformation passes or input to
the parser.</p>
</div>

<!-- Describe the typesetting conventions here. --> </div>

<!-- *********************************************************************** -->
<div class="doc_section"> <a name="identifiers">Identifiers</a> </div>
<!-- *********************************************************************** -->

<div class="doc_text">

<p>LLVM uses three different forms of identifiers, for different
purposes:</p>

<ol>
  <li>Named values are represented as a string of characters with a '%' prefix.
  For example, %foo, %DivisionByZero, %a.really.long.identifier.  The actual
  regular expression used is '<tt>%[a-zA-Z$._][a-zA-Z$._0-9]*</tt>'.
  Identifiers which require other characters in their names can be surrounded
  with quotes.  In this way, anything except a <tt>&quot;</tt> character can be used
  in a name.</li>

  <li>Unnamed values are represented as an unsigned numeric value with a '%'
  prefix.  For example, %12, %2, %44.</li>

  <li>Constants, which are described in a <a href="#constants">section about
  constants</a>, below.</li>
</ol>

<p>LLVM requires that values start with a '%' sign for two reasons: Compilers
don't need to worry about name clashes with reserved words, and the set of
reserved words may be expanded in the future without penalty.  Additionally,
unnamed identifiers allow a compiler to quickly come up with a temporary
variable without having to avoid symbol table conflicts.</p>

<p>Reserved words in LLVM are very similar to reserved words in other
languages. There are keywords for different opcodes 
('<tt><a href="#i_add">add</a></tt>', 
 '<tt><a href="#i_bitcast">bitcast</a></tt>', 
 '<tt><a href="#i_ret">ret</a></tt>', etc...), for primitive type names ('<tt><a
href="#t_void">void</a></tt>', '<tt><a href="#t_primitive">i32</a></tt>', etc...),
and others.  These reserved words cannot conflict with variable names, because
none of them start with a '%' character.</p>

<p>Here is an example of LLVM code to multiply the integer variable
'<tt>%X</tt>' by 8:</p>

<p>The easy way:</p>

<div class="doc_code">
<pre>
%result = <a href="#i_mul">mul</a> i32 %X, 8
</pre>
</div>

<p>After strength reduction:</p>

<div class="doc_code">
<pre>
%result = <a href="#i_shl">shl</a> i32 %X, i8 3
</pre>
</div>

<p>And the hard way:</p>

<div class="doc_code">
<pre>
<a href="#i_add">add</a> i32 %X, %X           <i>; yields {i32}:%0</i>
<a href="#i_add">add</a> i32 %0, %0           <i>; yields {i32}:%1</i>
%result = <a href="#i_add">add</a> i32 %1, %1
</pre>
</div>

<p>This last way of multiplying <tt>%X</tt> by 8 illustrates several
important lexical features of LLVM:</p>

<ol>

  <li>Comments are delimited with a '<tt>;</tt>' and go until the end of
  line.</li>

  <li>Unnamed temporaries are created when the result of a computation is not
  assigned to a named value.</li>

  <li>Unnamed temporaries are numbered sequentially</li>

</ol>

<p>...and it also shows a convention that we follow in this document.  When
demonstrating instructions, we will follow an instruction with a comment that
defines the type and name of value produced.  Comments are shown in italic
text.</p>

</div>

<!-- *********************************************************************** -->
<div class="doc_section"> <a name="highlevel">High Level Structure</a> </div>
<!-- *********************************************************************** -->

<!-- ======================================================================= -->
<div class="doc_subsection"> <a name="modulestructure">Module Structure</a>
</div>

<div class="doc_text">

<p>LLVM programs are composed of "Module"s, each of which is a
translation unit of the input programs.  Each module consists of
functions, global variables, and symbol table entries.  Modules may be
combined together with the LLVM linker, which merges function (and
global variable) definitions, resolves forward declarations, and merges
symbol table entries. Here is an example of the "hello world" module:</p>

<div class="doc_code">
<pre><i>; Declare the string constant as a global constant...</i>
<a href="#identifiers">@.LC0</a> = <a href="#linkage_internal">internal</a> <a
 href="#globalvars">constant</a> <a href="#t_array">[13 x i8]</a> c"hello world\0A\00"          <i>; [13 x i8]*</i>

<i>; External declaration of the puts function</i>
<a href="#functionstructure">declare</a> i32 @puts(i8 *)                                            <i>; i32(i8 *)* </i>

<i>; Definition of main function</i>
define i32 @main() {                                                 <i>; i32()* </i>
        <i>; Convert [13x i8 ]* to i8  *...</i>
        %cast210 = <a
 href="#i_getelementptr">getelementptr</a> [13 x i8 ]* @.LC0, i64 0, i64 0 <i>; i8 *</i>

        <i>; Call puts function to write out the string to stdout...</i>
        <a
 href="#i_call">call</a> i32 @puts(i8 * %cast210)                              <i>; i32</i>
        <a
 href="#i_ret">ret</a> i32 0<br>}<br>
</pre>
</div>

<p>This example is made up of a <a href="#globalvars">global variable</a>
named "<tt>.LC0</tt>", an external declaration of the "<tt>puts</tt>"
function, and a <a href="#functionstructure">function definition</a>
for "<tt>main</tt>".</p>

<p>In general, a module is made up of a list of global values,
where both functions and global variables are global values.  Global values are
represented by a pointer to a memory location (in this case, a pointer to an
array of char, and a pointer to a function), and have one of the following <a
href="#linkage">linkage types</a>.</p>

</div>

<!-- ======================================================================= -->
<div class="doc_subsection">
  <a name="linkage">Linkage Types</a>
</div>

<div class="doc_text">

<p>
All Global Variables and Functions have one of the following types of linkage:
</p>

<dl>

  <dt><tt><b><a name="linkage_internal">internal</a></b></tt> </dt>

  <dd>Global values with internal linkage are only directly accessible by
  objects in the current module.  In particular, linking code into a module with
  an internal global value may cause the internal to be renamed as necessary to
  avoid collisions.  Because the symbol is internal to the module, all
  references can be updated.  This corresponds to the notion of the
  '<tt>static</tt>' keyword in C.
  </dd>

  <dt><tt><b><a name="linkage_linkonce">linkonce</a></b></tt>: </dt>

  <dd>Globals with "<tt>linkonce</tt>" linkage are merged with other globals of
  the same name when linkage occurs.  This is typically used to implement 
  inline functions, templates, or other code which must be generated in each 
  translation unit that uses it.  Unreferenced <tt>linkonce</tt> globals are 
  allowed to be discarded.
  </dd>

  <dt><tt><b><a name="linkage_weak">weak</a></b></tt>: </dt>

  <dd>"<tt>weak</tt>" linkage is exactly the same as <tt>linkonce</tt> linkage,
  except that unreferenced <tt>weak</tt> globals may not be discarded.  This is
  used for globals that may be emitted in multiple translation units, but that
  are not guaranteed to be emitted into every translation unit that uses them.
  One example of this are common globals in C, such as "<tt>int X;</tt>" at 
  global scope.
  </dd>

  <dt><tt><b><a name="linkage_appending">appending</a></b></tt>: </dt>

  <dd>"<tt>appending</tt>" linkage may only be applied to global variables of
  pointer to array type.  When two global variables with appending linkage are
  linked together, the two global arrays are appended together.  This is the
  LLVM, typesafe, equivalent of having the system linker append together
  "sections" with identical names when .o files are linked.
  </dd>

  <dt><tt><b><a name="linkage_externweak">extern_weak</a></b></tt>: </dt>
  <dd>The semantics of this linkage follow the ELF model: the symbol is weak
    until linked, if not linked, the symbol becomes null instead of being an
    undefined reference.
  </dd>

  <dt><tt><b><a name="linkage_external">externally visible</a></b></tt>:</dt>

  <dd>If none of the above identifiers are used, the global is externally
  visible, meaning that it participates in linkage and can be used to resolve
  external symbol references.
  </dd>
</dl>

  <p>
  The next two types of linkage are targeted for Microsoft Windows platform
  only. They are designed to support importing (exporting) symbols from (to)
  DLLs.
  </p>

  <dl>
  <dt><tt><b><a name="linkage_dllimport">dllimport</a></b></tt>: </dt>

  <dd>"<tt>dllimport</tt>" linkage causes the compiler to reference a function
    or variable via a global pointer to a pointer that is set up by the DLL
    exporting the symbol. On Microsoft Windows targets, the pointer name is
    formed by combining <code>_imp__</code> and the function or variable name.
  </dd>

  <dt><tt><b><a name="linkage_dllexport">dllexport</a></b></tt>: </dt>

  <dd>"<tt>dllexport</tt>" linkage causes the compiler to provide a global
    pointer to a pointer in a DLL, so that it can be referenced with the
    <tt>dllimport</tt> attribute. On Microsoft Windows targets, the pointer
    name is formed by combining <code>_imp__</code> and the function or variable
    name.
  </dd>

</dl>

<p><a name="linkage_external"></a>For example, since the "<tt>.LC0</tt>"
variable is defined to be internal, if another module defined a "<tt>.LC0</tt>"
variable and was linked with this one, one of the two would be renamed,
preventing a collision.  Since "<tt>main</tt>" and "<tt>puts</tt>" are
external (i.e., lacking any linkage declarations), they are accessible
outside of the current module.</p>
<p>It is illegal for a function <i>declaration</i>
to have any linkage type other than "externally visible", <tt>dllimport</tt>,
or <tt>extern_weak</tt>.</p>
<p>Aliases can have only <tt>external</tt>, <tt>internal</tt> and <tt>weak</tt>
linkages.
</div>

<!-- ======================================================================= -->
<div class="doc_subsection">
  <a name="callingconv">Calling Conventions</a>
</div>

<div class="doc_text">

<p>LLVM <a href="#functionstructure">functions</a>, <a href="#i_call">calls</a>
and <a href="#i_invoke">invokes</a> can all have an optional calling convention
specified for the call.  The calling convention of any pair of dynamic
caller/callee must match, or the behavior of the program is undefined.  The
following calling conventions are supported by LLVM, and more may be added in
the future:</p>

<dl>
  <dt><b>"<tt>ccc</tt>" - The C calling convention</b>:</dt>

  <dd>This calling convention (the default if no other calling convention is
  specified) matches the target C calling conventions.  This calling convention
  supports varargs function calls and tolerates some mismatch in the declared
  prototype and implemented declaration of the function (as does normal C). 
  </dd>

  <dt><b>"<tt>fastcc</tt>" - The fast calling convention</b>:</dt>

  <dd>This calling convention attempts to make calls as fast as possible
  (e.g. by passing things in registers).  This calling convention allows the
  target to use whatever tricks it wants to produce fast code for the target,
  without having to conform to an externally specified ABI.  Implementations of
  this convention should allow arbitrary tail call optimization to be supported.
  This calling convention does not support varargs and requires the prototype of
  all callees to exactly match the prototype of the function definition.
  </dd>

  <dt><b>"<tt>coldcc</tt>" - The cold calling convention</b>:</dt>

  <dd>This calling convention attempts to make code in the caller as efficient
  as possible under the assumption that the call is not commonly executed.  As
  such, these calls often preserve all registers so that the call does not break
  any live ranges in the caller side.  This calling convention does not support
  varargs and requires the prototype of all callees to exactly match the
  prototype of the function definition.
  </dd>

  <dt><b>"<tt>cc &lt;<em>n</em>&gt;</tt>" - Numbered convention</b>:</dt>

  <dd>Any calling convention may be specified by number, allowing
  target-specific calling conventions to be used.  Target specific calling
  conventions start at 64.
  </dd>
</dl>

<p>More calling conventions can be added/defined on an as-needed basis, to
support pascal conventions or any other well-known target-independent
convention.</p>

</div>

<!-- ======================================================================= -->
<div class="doc_subsection">
  <a name="visibility">Visibility Styles</a>
</div>

<div class="doc_text">

<p>
All Global Variables and Functions have one of the following visibility styles:
</p>

<dl>
  <dt><b>"<tt>default</tt>" - Default style</b>:</dt>

  <dd>On ELF, default visibility means that the declaration is visible to other
    modules and, in shared libraries, means that the declared entity may be
    overridden. On Darwin, default visibility means that the declaration is
    visible to other modules. Default visibility corresponds to "external
    linkage" in the language.
  </dd>

  <dt><b>"<tt>hidden</tt>" - Hidden style</b>:</dt>

  <dd>Two declarations of an object with hidden visibility refer to the same
    object if they are in the same shared object. Usually, hidden visibility
    indicates that the symbol will not be placed into the dynamic symbol table,
    so no other module (executable or shared library) can reference it
    directly.
  </dd>

  <dt><b>"<tt>protected</tt>" - Protected style</b>:</dt>

  <dd>On ELF, protected visibility indicates that the symbol will be placed in
  the dynamic symbol table, but that references within the defining module will
  bind to the local symbol. That is, the symbol cannot be overridden by another
  module.
  </dd>
</dl>

</div>

<!-- ======================================================================= -->
<div class="doc_subsection">
  <a name="globalvars">Global Variables</a>
</div>

<div class="doc_text">

<p>Global variables define regions of memory allocated at compilation time
instead of run-time.  Global variables may optionally be initialized, may have
an explicit section to be placed in, and may have an optional explicit alignment
specified.  A variable may be defined as "thread_local", which means that it
will not be shared by threads (each thread will have a separated copy of the
variable).  A variable may be defined as a global "constant," which indicates
that the contents of the variable will <b>never</b> be modified (enabling better
optimization, allowing the global data to be placed in the read-only section of
an executable, etc).  Note that variables that need runtime initialization
cannot be marked "constant" as there is a store to the variable.</p>

<p>
LLVM explicitly allows <em>declarations</em> of global variables to be marked
constant, even if the final definition of the global is not.  This capability
can be used to enable slightly better optimization of the program, but requires
the language definition to guarantee that optimizations based on the
'constantness' are valid for the translation units that do not include the
definition.
</p>

<p>As SSA values, global variables define pointer values that are in
scope (i.e. they dominate) all basic blocks in the program.  Global
variables always define a pointer to their "content" type because they
describe a region of memory, and all memory objects in LLVM are
accessed through pointers.</p>

<p>LLVM allows an explicit section to be specified for globals.  If the target
supports it, it will emit globals to the section specified.</p>

<p>An explicit alignment may be specified for a global.  If not present, or if
the alignment is set to zero, the alignment of the global is set by the target
to whatever it feels convenient.  If an explicit alignment is specified, the 
global is forced to have at least that much alignment.  All alignments must be
a power of 2.</p>

<p>For example, the following defines a global with an initializer, section,
   and alignment:</p>

<div class="doc_code">
<pre>
@G = constant float 1.0, section "foo", align 4
</pre>
</div>

</div>


<!-- ======================================================================= -->
<div class="doc_subsection">
  <a name="functionstructure">Functions</a>
</div>

<div class="doc_text">

<p>LLVM function definitions consist of the "<tt>define</tt>" keyord, 
an optional <a href="#linkage">linkage type</a>, an optional 
<a href="#visibility">visibility style</a>, an optional 
<a href="#callingconv">calling convention</a>, a return type, an optional
<a href="#paramattrs">parameter attribute</a> for the return type, a function 
name, a (possibly empty) argument list (each with optional 
<a href="#paramattrs">parameter attributes</a>), an optional section, an
optional alignment, an opening curly brace, a list of basic blocks, and a
closing curly brace.  

LLVM function declarations consist of the "<tt>declare</tt>" keyword, an
optional <a href="#linkage">linkage type</a>, an optional
<a href="#visibility">visibility style</a>, an optional 
<a href="#callingconv">calling convention</a>, a return type, an optional
<a href="#paramattrs">parameter attribute</a> for the return type, a function 
name, a possibly empty list of arguments, and an optional alignment.</p>

<p>A function definition contains a list of basic blocks, forming the CFG for
the function.  Each basic block may optionally start with a label (giving the
basic block a symbol table entry), contains a list of instructions, and ends
with a <a href="#terminators">terminator</a> instruction (such as a branch or
function return).</p>

<p>The first basic block in a function is special in two ways: it is immediately
executed on entrance to the function, and it is not allowed to have predecessor
basic blocks (i.e. there can not be any branches to the entry block of a
function).  Because the block can have no predecessors, it also cannot have any
<a href="#i_phi">PHI nodes</a>.</p>

<p>LLVM allows an explicit section to be specified for functions.  If the target
supports it, it will emit functions to the section specified.</p>

<p>An explicit alignment may be specified for a function.  If not present, or if
the alignment is set to zero, the alignment of the function is set by the target
to whatever it feels convenient.  If an explicit alignment is specified, the
function is forced to have at least that much alignment.  All alignments must be
a power of 2.</p>

</div>


<!-- ======================================================================= -->
<div class="doc_subsection">
  <a name="aliasstructure">Aliases</a>
</div>
<div class="doc_text">
  <p>Aliases act as "second name" for the aliasee value (which can be either
  function or global variable or bitcast of global value). Aliases may have an
  optional <a href="#linkage">linkage type</a>, and an
  optional <a href="#visibility">visibility style</a>.</p>

  <h5>Syntax:</h5>

<div class="doc_code">
<pre>
@&lt;Name&gt; = [Linkage] [Visibility] alias &lt;AliaseeTy&gt; @&lt;Aliasee&gt;
</pre>
</div>

</div>



<!-- ======================================================================= -->
<div class="doc_subsection"><a name="paramattrs">Parameter Attributes</a></div>
<div class="doc_text">
  <p>The return type and each parameter of a function type may have a set of
  <i>parameter attributes</i> associated with them. Parameter attributes are
  used to communicate additional information about the result or parameters of
  a function. Parameter attributes are considered to be part of the function
  type so two functions types that differ only by the parameter attributes 
  are different function types.</p>

  <p>Parameter attributes are simple keywords that follow the type specified. If
  multiple parameter attributes are needed, they are space separated. For 
  example:</p>

<div class="doc_code">
<pre>
%someFunc = i16 (i8 signext %someParam) zeroext
%someFunc = i16 (i8 zeroext %someParam) zeroext
</pre>
</div>

  <p>Note that the two function types above are unique because the parameter has
  a different attribute (<tt>signext</tt> in the first one, <tt>zeroext</tt> in
  the second).  Also note that the attribute for the function result 
  (<tt>zeroext</tt>) comes immediately after the argument list.</p>

  <p>Currently, only the following parameter attributes are defined:</p>
  <dl>
    <dt><tt>zeroext</tt></dt>
    <dd>This indicates that the parameter should be zero extended just before
    a call to this function.</dd>
    <dt><tt>signext</tt></dt>
    <dd>This indicates that the parameter should be sign extended just before
    a call to this function.</dd>
    <dt><tt>inreg</tt></dt>
    <dd>This indicates that the parameter should be placed in register (if
    possible) during assembling function call. Support for this attribute is
    target-specific</dd>
    <dt><tt>sret</tt></dt>
    <dd>This indicates that the parameter specifies the address of a structure
    that is the return value of the function in the source program.</dd>
    <dt><tt>noalias</tt></dt>
    <dd>This indicates that the parameter not alias any other object or any 
    other "noalias" objects during the function call.
    <dt><tt>noreturn</tt></dt>
    <dd>This function attribute indicates that the function never returns. This
    indicates to LLVM that every call to this function should be treated as if
    an <tt>unreachable</tt> instruction immediately followed the call.</dd> 
    <dt><tt>nounwind</tt></dt>
    <dd>This function attribute indicates that the function type does not use
    the unwind instruction and does not allow stack unwinding to propagate
    through it.</dd>
  </dl>

</div>

<!-- ======================================================================= -->
<div class="doc_subsection">
  <a name="moduleasm">Module-Level Inline Assembly</a>
</div>

<div class="doc_text">
<p>
Modules may contain "module-level inline asm" blocks, which corresponds to the
GCC "file scope inline asm" blocks.  These blocks are internally concatenated by
LLVM and treated as a single unit, but may be separated in the .ll file if
desired.  The syntax is very simple:
</p>

<div class="doc_code">
<pre>
module asm "inline asm code goes here"
module asm "more can go here"
</pre>
</div>

<p>The strings can contain any character by escaping non-printable characters.
   The escape sequence used is simply "\xx" where "xx" is the two digit hex code
   for the number.
</p>

<p>
  The inline asm code is simply printed to the machine code .s file when
  assembly code is generated.
</p>
</div>

<!-- ======================================================================= -->
<div class="doc_subsection">
  <a name="datalayout">Data Layout</a>
</div>

<div class="doc_text">
<p>A module may specify a target specific data layout string that specifies how
data is to be laid out in memory. The syntax for the data layout is simply:</p>
<pre>    target datalayout = "<i>layout specification</i>"</pre>
<p>The <i>layout specification</i> consists of a list of specifications 
separated by the minus sign character ('-').  Each specification starts with a 
letter and may include other information after the letter to define some 
aspect of the data layout.  The specifications accepted are as follows: </p>
<dl>
  <dt><tt>E</tt></dt>
  <dd>Specifies that the target lays out data in big-endian form. That is, the
  bits with the most significance have the lowest address location.</dd>
  <dt><tt>e</tt></dt>
  <dd>Specifies that hte target lays out data in little-endian form. That is,
  the bits with the least significance have the lowest address location.</dd>
  <dt><tt>p:<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
  <dd>This specifies the <i>size</i> of a pointer and its <i>abi</i> and 
  <i>preferred</i> alignments. All sizes are in bits. Specifying the <i>pref</i>
  alignment is optional. If omitted, the preceding <tt>:</tt> should be omitted
  too.</dd>
  <dt><tt>i<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
  <dd>This specifies the alignment for an integer type of a given bit
  <i>size</i>. The value of <i>size</i> must be in the range [1,2^23).</dd>
  <dt><tt>v<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
  <dd>This specifies the alignment for a vector type of a given bit 
  <i>size</i>.</dd>
  <dt><tt>f<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
  <dd>This specifies the alignment for a floating point type of a given bit 
  <i>size</i>. The value of <i>size</i> must be either 32 (float) or 64
  (double).</dd>
  <dt><tt>a<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
  <dd>This specifies the alignment for an aggregate type of a given bit
  <i>size</i>.</dd>
</dl>
<p>When constructing the data layout for a given target, LLVM starts with a
default set of specifications which are then (possibly) overriden by the
specifications in the <tt>datalayout</tt> keyword. The default specifications
are given in this list:</p>
<ul>
  <li><tt>E</tt> - big endian</li>
  <li><tt>p:32:64:64</tt> - 32-bit pointers with 64-bit alignment</li>
  <li><tt>i1:8:8</tt> - i1 is 8-bit (byte) aligned</li>
  <li><tt>i8:8:8</tt> - i8 is 8-bit (byte) aligned</li>
  <li><tt>i16:16:16</tt> - i16 is 16-bit aligned</li>
  <li><tt>i32:32:32</tt> - i32 is 32-bit aligned</li>
  <li><tt>i64:32:64</tt> - i64 has abi alignment of 32-bits but preferred
  alignment of 64-bits</li>
  <li><tt>f32:32:32</tt> - float is 32-bit aligned</li>
  <li><tt>f64:64:64</tt> - double is 64-bit aligned</li>
  <li><tt>v64:64:64</tt> - 64-bit vector is 64-bit aligned</li>
  <li><tt>v128:128:128</tt> - 128-bit vector is 128-bit aligned</li>
  <li><tt>a0:0:1</tt> - aggregates are 8-bit aligned</li>
</ul>
<p>When llvm is determining the alignment for a given type, it uses the 
following rules:
<ol>
  <li>If the type sought is an exact match for one of the specifications, that
  specification is used.</li>
  <li>If no match is found, and the type sought is an integer type, then the
  smallest integer type that is larger than the bitwidth of the sought type is
  used. If none of the specifications are larger than the bitwidth then the the
  largest integer type is used. For example, given the default specifications
  above, the i7 type will use the alignment of i8 (next largest) while both
  i65 and i256 will use the alignment of i64 (largest specified).</li>
  <li>If no match is found, and the type sought is a vector type, then the
  largest vector type that is smaller than the sought vector type will be used
  as a fall back.  This happens because <128 x double> can be implemented in 
  terms of 64 <2 x double>, for example.</li>
</ol>
</div>

<!-- *********************************************************************** -->
<div class="doc_section"> <a name="typesystem">Type System</a> </div>
<!-- *********************************************************************** -->

<div class="doc_text">

<p>The LLVM type system is one of the most important features of the
intermediate representation.  Being typed enables a number of
optimizations to be performed on the IR directly, without having to do
extra analyses on the side before the transformation.  A strong type
system makes it easier to read the generated code and enables novel
analyses and transformations that are not feasible to perform on normal
three address code representations.</p>

</div>

<!-- ======================================================================= -->
<div class="doc_subsection"> <a name="t_primitive">Primitive Types</a> </div>
<div class="doc_text">
<p>The primitive types are the fundamental building blocks of the LLVM
system. The current set of primitive types is as follows:</p>

<table class="layout">
  <tr class="layout">
    <td class="left">
      <table>
        <tbody>
        <tr><th>Type</th><th>Description</th></tr>
        <tr><td><tt><a name="t_void">void</a></tt></td><td>No value</td></tr>
        <tr><td><tt>label</tt></td><td>Branch destination</td></tr>
        </tbody>
      </table>
    </td>
    <td class="right">
      <table>
        <tbody>
          <tr><th>Type</th><th>Description</th></tr>
          <tr><td><tt>float</tt></td><td>32-bit floating point value</td></tr>
         <tr><td><tt>double</tt></td><td>64-bit floating point value</td></tr>
        </tbody>
      </table>
    </td>
  </tr>
</table>
</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection"> <a name="t_classifications">Type
Classifications</a> </div>
<div class="doc_text">
<p>These different primitive types fall into a few useful
classifications:</p>

<table border="1" cellspacing="0" cellpadding="4">
  <tbody>
    <tr><th>Classification</th><th>Types</th></tr>
    <tr>
      <td><a name="t_integer">integer</a></td>
      <td><tt>i1, i2, i3, ... i8, ... i16, ... i32, ... i64, ... </tt></td>
    </tr>
    <tr>
      <td><a name="t_floating">floating point</a></td>
      <td><tt>float, double</tt></td>
    </tr>
    <tr>
      <td><a name="t_firstclass">first class</a></td>
      <td><tt>i1, ..., float, double, <br/>
          <a href="#t_pointer">pointer</a>,<a href="#t_vector">vector</a></tt>
      </td>
    </tr>
  </tbody>
</table>

<p>The <a href="#t_firstclass">first class</a> types are perhaps the
most important.  Values of these types are the only ones which can be
produced by instructions, passed as arguments, or used as operands to
instructions.  This means that all structures and arrays must be
manipulated either by pointer or by component.</p>
</div>

<!-- ======================================================================= -->
<div class="doc_subsection"> <a name="t_derived">Derived Types</a> </div>

<div class="doc_text">

<p>The real power in LLVM comes from the derived types in the system. 
This is what allows a programmer to represent arrays, functions,
pointers, and other useful types.  Note that these derived types may be
recursive: For example, it is possible to have a two dimensional array.</p>

</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection"> <a name="t_integer">Integer Type</a> </div>

<div class="doc_text">

<h5>Overview:</h5>
<p>The integer type is a very simple derived type that simply specifies an
arbitrary bit width for the integer type desired. Any bit width from 1 bit to
2^23-1 (about 8 million) can be specified.</p>

<h5>Syntax:</h5>

<pre>
  iN
</pre>

<p>The number of bits the integer will occupy is specified by the <tt>N</tt>
value.</p>

<h5>Examples:</h5>
<table class="layout">
  <tr class="layout">
    <td class="left">
      <tt>i1</tt><br/>
      <tt>i4</tt><br/>
      <tt>i8</tt><br/>
      <tt>i16</tt><br/>
      <tt>i32</tt><br/>
      <tt>i42</tt><br/>
      <tt>i64</tt><br/>
      <tt>i1942652</tt><br/>
    </td>
    <td class="left">
      A boolean integer of 1 bit<br/>
      A nibble sized integer of 4 bits.<br/>
      A byte sized integer of 8 bits.<br/>
      A half word sized integer of 16 bits.<br/>
      A word sized integer of 32 bits.<br/>
      An integer whose bit width is the answer. <br/>
      A double word sized integer of 64 bits.<br/>
      A really big integer of over 1 million bits.<br/>
    </td>
  </tr>
</table>
</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection"> <a name="t_array">Array Type</a> </div>

<div class="doc_text">

<h5>Overview:</h5>

<p>The array type is a very simple derived type that arranges elements
sequentially in memory.  The array type requires a size (number of
elements) and an underlying data type.</p>

<h5>Syntax:</h5>

<pre>
  [&lt;# elements&gt; x &lt;elementtype&gt;]
</pre>

<p>The number of elements is a constant integer value; elementtype may
be any type with a size.</p>

<h5>Examples:</h5>
<table class="layout">
  <tr class="layout">
    <td class="left">
      <tt>[40 x i32 ]</tt><br/>
      <tt>[41 x i32 ]</tt><br/>
      <tt>[40 x i8]</tt><br/>
    </td>
    <td class="left">
      Array of 40 32-bit integer values.<br/>
      Array of 41 32-bit integer values.<br/>
      Array of 40 8-bit integer values.<br/>
    </td>
  </tr>
</table>
<p>Here are some examples of multidimensional arrays:</p>
<table class="layout">
  <tr class="layout">
    <td class="left">
      <tt>[3 x [4 x i32]]</tt><br/>
      <tt>[12 x [10 x float]]</tt><br/>
      <tt>[2 x [3 x [4 x i16]]]</tt><br/>
    </td>
    <td class="left">
      3x4 array of 32-bit integer values.<br/>
      12x10 array of single precision floating point values.<br/>
      2x3x4 array of 16-bit integer  values.<br/>
    </td>
  </tr>
</table>

<p>Note that 'variable sized arrays' can be implemented in LLVM with a zero 
length array.  Normally, accesses past the end of an array are undefined in
LLVM (e.g. it is illegal to access the 5th element of a 3 element array).
As a special case, however, zero length arrays are recognized to be variable
length.  This allows implementation of 'pascal style arrays' with the  LLVM
type "{ i32, [0 x float]}", for example.</p>

</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection"> <a name="t_function">Function Type</a> </div>
<div class="doc_text">
<h5>Overview:</h5>
<p>The function type can be thought of as a function signature.  It
consists of a return type and a list of formal parameter types. 
Function types are usually used to build virtual function tables
(which are structures of pointers to functions), for indirect function
calls, and when defining a function.</p>
<p>
The return type of a function type cannot be an aggregate type.
</p>
<h5>Syntax:</h5>
<pre>  &lt;returntype&gt; (&lt;parameter list&gt;)<br></pre>
<p>...where '<tt>&lt;parameter list&gt;</tt>' is a comma-separated list of type
specifiers.  Optionally, the parameter list may include a type <tt>...</tt>,
which indicates that the function takes a variable number of arguments.
Variable argument functions can access their arguments with the <a
 href="#int_varargs">variable argument handling intrinsic</a> functions.</p>
<h5>Examples:</h5>
<table class="layout">
  <tr class="layout">
    <td class="left"><tt>i32 (i32)</tt></td>
    <td class="left">function taking an <tt>i32</tt>, returning an <tt>i32</tt>
    </td>
  </tr><tr class="layout">
    <td class="left"><tt>float&nbsp;(i16&nbsp;signext,&nbsp;i32&nbsp;*)&nbsp;*
    </tt></td>
    <td class="left"><a href="#t_pointer">Pointer</a> to a function that takes 
      an <tt>i16</tt> that should be sign extended and a 
      <a href="#t_pointer">pointer</a> to <tt>i32</tt>, returning 
      <tt>float</tt>.
    </td>
  </tr><tr class="layout">
    <td class="left"><tt>i32 (i8*, ...)</tt></td>
    <td class="left">A vararg function that takes at least one 
      <a href="#t_pointer">pointer</a> to <tt>i8 </tt> (char in C), 
      which returns an integer.  This is the signature for <tt>printf</tt> in 
      LLVM.
    </td>
  </tr>
</table>

</div>
<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection"> <a name="t_struct">Structure Type</a> </div>
<div class="doc_text">
<h5>Overview:</h5>
<p>The structure type is used to represent a collection of data members
together in memory.  The packing of the field types is defined to match
the ABI of the underlying processor.  The elements of a structure may
be any type that has a size.</p>
<p>Structures are accessed using '<tt><a href="#i_load">load</a></tt>
and '<tt><a href="#i_store">store</a></tt>' by getting a pointer to a
field with the '<tt><a href="#i_getelementptr">getelementptr</a></tt>'
instruction.</p>
<h5>Syntax:</h5>
<pre>  { &lt;type list&gt; }<br></pre>
<h5>Examples:</h5>
<table class="layout">
  <tr class="layout">
    <td class="left"><tt>{ i32, i32, i32 }</tt></td>
    <td class="left">A triple of three <tt>i32</tt> values</td>
  </tr><tr class="layout">
    <td class="left"><tt>{&nbsp;float,&nbsp;i32&nbsp;(i32)&nbsp;*&nbsp;}</tt></td>
    <td class="left">A pair, where the first element is a <tt>float</tt> and the
      second element is a <a href="#t_pointer">pointer</a> to a
      <a href="#t_function">function</a> that takes an <tt>i32</tt>, returning
      an <tt>i32</tt>.</td>
  </tr>
</table>
</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection"> <a name="t_pstruct">Packed Structure Type</a>
</div>
<div class="doc_text">
<h5>Overview:</h5>
<p>The packed structure type is used to represent a collection of data members
together in memory.  There is no padding between fields.  Further, the alignment
of a packed structure is 1 byte.  The elements of a packed structure may
be any type that has a size.</p>
<p>Structures are accessed using '<tt><a href="#i_load">load</a></tt>
and '<tt><a href="#i_store">store</a></tt>' by getting a pointer to a
field with the '<tt><a href="#i_getelementptr">getelementptr</a></tt>'
instruction.</p>
<h5>Syntax:</h5>
<pre>  &lt; { &lt;type list&gt; } &gt; <br></pre>
<h5>Examples:</h5>
<table class="layout">
  <tr class="layout">
    <td class="left"><tt>&lt; { i32, i32, i32 } &gt;</tt></td>
    <td class="left">A triple of three <tt>i32</tt> values</td>
  </tr><tr class="layout">
  <td class="left"><tt>&lt;&nbsp;{&nbsp;float,&nbsp;i32&nbsp;(i32)&nbsp;*&nbsp;}&nbsp;&gt;</tt></td>
    <td class="left">A pair, where the first element is a <tt>float</tt> and the
      second element is a <a href="#t_pointer">pointer</a> to a
      <a href="#t_function">function</a> that takes an <tt>i32</tt>, returning
      an <tt>i32</tt>.</td>
  </tr>
</table>
</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection"> <a name="t_pointer">Pointer Type</a> </div>
<div class="doc_text">
<h5>Overview:</h5>
<p>As in many languages, the pointer type represents a pointer or
reference to another object, which must live in memory.</p>
<h5>Syntax:</h5>
<pre>  &lt;type&gt; *<br></pre>
<h5>Examples:</h5>
<table class="layout">
  <tr class="layout">
    <td class="left">
      <tt>[4x i32]*</tt><br/>
      <tt>i32 (i32 *) *</tt><br/>
    </td>
    <td class="left">
      A <a href="#t_pointer">pointer</a> to <a href="#t_array">array</a> of
      four <tt>i32</tt> values<br/>
      A <a href="#t_pointer">pointer</a> to a <a
      href="#t_function">function</a> that takes an <tt>i32*</tt>, returning an
      <tt>i32</tt>.<br/>
    </td>
  </tr>
</table>
</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection"> <a name="t_vector">Vector Type</a> </div>
<div class="doc_text">

<h5>Overview:</h5>

<p>A vector type is a simple derived type that represents a vector
of elements.  Vector types are used when multiple primitive data 
are operated in parallel using a single instruction (SIMD). 
A vector type requires a size (number of
elements) and an underlying primitive data type.  Vectors must have a power
of two length (1, 2, 4, 8, 16 ...).  Vector types are
considered <a href="#t_firstclass">first class</a>.</p>

<h5>Syntax:</h5>

<pre>
  &lt; &lt;# elements&gt; x &lt;elementtype&gt; &gt;
</pre>

<p>The number of elements is a constant integer value; elementtype may
be any integer or floating point type.</p>

<h5>Examples:</h5>

<table class="layout">
  <tr class="layout">
    <td class="left">
      <tt>&lt;4 x i32&gt;</tt><br/>
      <tt>&lt;8 x float&gt;</tt><br/>
      <tt>&lt;2 x i64&gt;</tt><br/>
    </td>
    <td class="left">
      Vector of 4 32-bit integer values.<br/>
      Vector of 8 floating-point values.<br/>
      Vector of 2 64-bit integer values.<br/>
    </td>
  </tr>
</table>
</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection"> <a name="t_opaque">Opaque Type</a> </div>
<div class="doc_text">

<h5>Overview:</h5>

<p>Opaque types are used to represent unknown types in the system.  This
corresponds (for example) to the C notion of a foward declared structure type.
In LLVM, opaque types can eventually be resolved to any type (not just a
structure type).</p>

<h5>Syntax:</h5>

<pre>
  opaque
</pre>

<h5>Examples:</h5>

<table class="layout">
  <tr class="layout">
    <td class="left">
      <tt>opaque</tt>
    </td>
    <td class="left">
      An opaque type.<br/>
    </td>
  </tr>
</table>
</div>


<!-- *********************************************************************** -->
<div class="doc_section"> <a name="constants">Constants</a> </div>
<!-- *********************************************************************** -->

<div class="doc_text">

<p>LLVM has several different basic types of constants.  This section describes
them all and their syntax.</p>

</div>

<!-- ======================================================================= -->
<div class="doc_subsection"><a name="simpleconstants">Simple Constants</a></div>

<div class="doc_text">

<dl>
  <dt><b>Boolean constants</b></dt>

  <dd>The two strings '<tt>true</tt>' and '<tt>false</tt>' are both valid
  constants of the <tt><a href="#t_primitive">i1</a></tt> type.
  </dd>

  <dt><b>Integer constants</b></dt>

  <dd>Standard integers (such as '4') are constants of the <a
  href="#t_integer">integer</a> type.  Negative numbers may be used with 
  integer types.
  </dd>

  <dt><b>Floating point constants</b></dt>

  <dd>Floating point constants use standard decimal notation (e.g. 123.421),
  exponential notation (e.g. 1.23421e+2), or a more precise hexadecimal
  notation (see below).  Floating point constants must have a <a
  href="#t_floating">floating point</a> type. </dd>

  <dt><b>Null pointer constants</b></dt>

  <dd>The identifier '<tt>null</tt>' is recognized as a null pointer constant
  and must be of <a href="#t_pointer">pointer type</a>.</dd>

</dl>

<p>The one non-intuitive notation for constants is the optional hexadecimal form
of floating point constants.  For example, the form '<tt>double
0x432ff973cafa8000</tt>' is equivalent to (but harder to read than) '<tt>double
4.5e+15</tt>'.  The only time hexadecimal floating point constants are required
(and the only time that they are generated by the disassembler) is when a 
floating point constant must be emitted but it cannot be represented as a 
decimal floating point number.  For example, NaN's, infinities, and other 
special values are represented in their IEEE hexadecimal format so that 
assembly and disassembly do not cause any bits to change in the constants.</p>

</div>

<!-- ======================================================================= -->
<div class="doc_subsection"><a name="aggregateconstants">Aggregate Constants</a>
</div>

<div class="doc_text">
<p>Aggregate constants arise from aggregation of simple constants
and smaller aggregate constants.</p>

<dl>
  <dt><b>Structure constants</b></dt>

  <dd>Structure constants are represented with notation similar to structure
  type definitions (a comma separated list of elements, surrounded by braces
  (<tt>{}</tt>)).  For example: "<tt>{ i32 4, float 17.0, i32* %G }</tt>",
  where "<tt>%G</tt>" is declared as "<tt>@G = external global i32</tt>".  Structure constants
  must have <a href="#t_struct">structure type</a>, and the number and
  types of elements must match those specified by the type.
  </dd>

  <dt><b>Array constants</b></dt>

  <dd>Array constants are represented with notation similar to array type
  definitions (a comma separated list of elements, surrounded by square brackets
  (<tt>[]</tt>)).  For example: "<tt>[ i32 42, i32 11, i32 74 ]</tt>".  Array
  constants must have <a href="#t_array">array type</a>, and the number and
  types of elements must match those specified by the type.
  </dd>

  <dt><b>Vector constants</b></dt>

  <dd>Vector constants are represented with notation similar to vector type
  definitions (a comma separated list of elements, surrounded by
  less-than/greater-than's (<tt>&lt;&gt;</tt>)).  For example: "<tt>&lt; i32 42,
  i32 11, i32 74, i32 100 &gt;</tt>".  Vector constants must have <a
  href="#t_vector">vector type</a>, and the number and types of elements must
  match those specified by the type.
  </dd>

  <dt><b>Zero initialization</b></dt>

  <dd>The string '<tt>zeroinitializer</tt>' can be used to zero initialize a
  value to zero of <em>any</em> type, including scalar and aggregate types.
  This is often used to avoid having to print large zero initializers (e.g. for
  large arrays) and is always exactly equivalent to using explicit zero
  initializers.
  </dd>
</dl>

</div>

<!-- ======================================================================= -->
<div class="doc_subsection">
  <a name="globalconstants">Global Variable and Function Addresses</a>
</div>

<div class="doc_text">

<p>The addresses of <a href="#globalvars">global variables</a> and <a
href="#functionstructure">functions</a> are always implicitly valid (link-time)
constants.  These constants are explicitly referenced when the <a
href="#identifiers">identifier for the global</a> is used and always have <a
href="#t_pointer">pointer</a> type. For example, the following is a legal LLVM
file:</p>

<div class="doc_code">
<pre>
@X = global i32 17
@Y = global i32 42
@Z = global [2 x i32*] [ i32* @X, i32* @Y ]
</pre>
</div>

</div>

<!-- ======================================================================= -->
<div class="doc_subsection"><a name="undefvalues">Undefined Values</a></div>
<div class="doc_text">
  <p>The string '<tt>undef</tt>' is recognized as a type-less constant that has 
  no specific value.  Undefined values may be of any type and be used anywhere 
  a constant is permitted.</p>

  <p>Undefined values indicate to the compiler that the program is well defined
  no matter what value is used, giving the compiler more freedom to optimize.
  </p>
</div>

<!-- ======================================================================= -->
<div class="doc_subsection"><a name="constantexprs">Constant Expressions</a>
</div>

<div class="doc_text">

<p>Constant expressions are used to allow expressions involving other constants
to be used as constants.  Constant expressions may be of any <a
href="#t_firstclass">first class</a> type and may involve any LLVM operation
that does not have side effects (e.g. load and call are not supported).  The
following is the syntax for constant expressions:</p>

<dl>
  <dt><b><tt>trunc ( CST to TYPE )</tt></b></dt>
  <dd>Truncate a constant to another type. The bit size of CST must be larger 
  than the bit size of TYPE. Both types must be integers.</dd>

  <dt><b><tt>zext ( CST to TYPE )</tt></b></dt>
  <dd>Zero extend a constant to another type. The bit size of CST must be 
  smaller or equal to the bit size of TYPE.  Both types must be integers.</dd>

  <dt><b><tt>sext ( CST to TYPE )</tt></b></dt>
  <dd>Sign extend a constant to another type. The bit size of CST must be 
  smaller or equal to the bit size of TYPE.  Both types must be integers.</dd>

  <dt><b><tt>fptrunc ( CST to TYPE )</tt></b></dt>
  <dd>Truncate a floating point constant to another floating point type. The 
  size of CST must be larger than the size of TYPE. Both types must be 
  floating point.</dd>

  <dt><b><tt>fpext ( CST to TYPE )</tt></b></dt>
  <dd>Floating point extend a constant to another type. The size of CST must be 
  smaller or equal to the size of TYPE. Both types must be floating point.</dd>

  <dt><b><tt>fp2uint ( CST to TYPE )</tt></b></dt>
  <dd>Convert a floating point constant to the corresponding unsigned integer
  constant. TYPE must be an integer type. CST must be floating point. If the 
  value won't fit in the integer type, the results are undefined.</dd>

  <dt><b><tt>fptosi ( CST to TYPE )</tt></b></dt>
  <dd>Convert a floating point constant to the corresponding signed integer
  constant. TYPE must be an integer type. CST must be floating point. If the 
  value won't fit in the integer type, the results are undefined.</dd>

  <dt><b><tt>uitofp ( CST to TYPE )</tt></b></dt>
  <dd>Convert an unsigned integer constant to the corresponding floating point
  constant. TYPE must be floating point. CST must be of integer type. If the
  value won't fit in the floating point type, the results are undefined.</dd>

  <dt><b><tt>sitofp ( CST to TYPE )</tt></b></dt>
  <dd>Convert a signed integer constant to the corresponding floating point
  constant. TYPE must be floating point. CST must be of integer type. If the
  value won't fit in the floating point type, the results are undefined.</dd>

  <dt><b><tt>ptrtoint ( CST to TYPE )</tt></b></dt>
  <dd>Convert a pointer typed constant to the corresponding integer constant
  TYPE must be an integer type. CST must be of pointer type. The CST value is
  zero extended, truncated, or unchanged to make it fit in TYPE.</dd>

  <dt><b><tt>inttoptr ( CST to TYPE )</tt></b></dt>
  <dd>Convert a integer constant to a pointer constant.  TYPE must be a
  pointer type.  CST must be of integer type. The CST value is zero extended, 
  truncated, or unchanged to make it fit in a pointer size. This one is 
  <i>really</i> dangerous!</dd>

  <dt><b><tt>bitcast ( CST to TYPE )</tt></b></dt>
  <dd>Convert a constant, CST, to another TYPE. The size of CST and TYPE must be
  identical (same number of bits). The conversion is done as if the CST value
  was stored to memory and read back as TYPE. In other words, no bits change 
  with this operator, just the type.  This can be used for conversion of
  vector types to any other type, as long as they have the same bit width. For
  pointers it is only valid to cast to another pointer type.
  </dd>

  <dt><b><tt>getelementptr ( CSTPTR, IDX0, IDX1, ... )</tt></b></dt>

  <dd>Perform the <a href="#i_getelementptr">getelementptr operation</a> on
  constants.  As with the <a href="#i_getelementptr">getelementptr</a>
  instruction, the index list may have zero or more indexes, which are required
  to make sense for the type of "CSTPTR".</dd>

  <dt><b><tt>select ( COND, VAL1, VAL2 )</tt></b></dt>

  <dd>Perform the <a href="#i_select">select operation</a> on
  constants.</dd>

  <dt><b><tt>icmp COND ( VAL1, VAL2 )</tt></b></dt>
  <dd>Performs the <a href="#i_icmp">icmp operation</a> on constants.</dd>

  <dt><b><tt>fcmp COND ( VAL1, VAL2 )</tt></b></dt>
  <dd>Performs the <a href="#i_fcmp">fcmp operation</a> on constants.</dd>

  <dt><b><tt>extractelement ( VAL, IDX )</tt></b></dt>

  <dd>Perform the <a href="#i_extractelement">extractelement
  operation</a> on constants.

  <dt><b><tt>insertelement ( VAL, ELT, IDX )</tt></b></dt>

  <dd>Perform the <a href="#i_insertelement">insertelement
    operation</a> on constants.</dd>


  <dt><b><tt>shufflevector ( VEC1, VEC2, IDXMASK )</tt></b></dt>

  <dd>Perform the <a href="#i_shufflevector">shufflevector
    operation</a> on constants.</dd>

  <dt><b><tt>OPCODE ( LHS, RHS )</tt></b></dt>

  <dd>Perform the specified operation of the LHS and RHS constants. OPCODE may 
  be any of the <a href="#binaryops">binary</a> or <a href="#bitwiseops">bitwise
  binary</a> operations.  The constraints on operands are the same as those for
  the corresponding instruction (e.g. no bitwise operations on floating point
  values are allowed).</dd>
</dl>
</div>

<!-- *********************************************************************** -->
<div class="doc_section"> <a name="othervalues">Other Values</a> </div>
<!-- *********************************************************************** -->

<!-- ======================================================================= -->
<div class="doc_subsection">
<a name="inlineasm">Inline Assembler Expressions</a>
</div>

<div class="doc_text">

<p>
LLVM supports inline assembler expressions (as opposed to <a href="#moduleasm">
Module-Level Inline Assembly</a>) through the use of a special value.  This
value represents the inline assembler as a string (containing the instructions
to emit), a list of operand constraints (stored as a string), and a flag that 
indicates whether or not the inline asm expression has side effects.  An example
inline assembler expression is:
</p>

<div class="doc_code">
<pre>
i32 (i32) asm "bswap $0", "=r,r"
</pre>
</div>

<p>
Inline assembler expressions may <b>only</b> be used as the callee operand of
a <a href="#i_call"><tt>call</tt> instruction</a>.  Thus, typically we have:
</p>

<div class="doc_code">
<pre>
%X = call i32 asm "<a href="#int_bswap">bswap</a> $0", "=r,r"(i32 %Y)
</pre>
</div>

<p>
Inline asms with side effects not visible in the constraint list must be marked
as having side effects.  This is done through the use of the
'<tt>sideeffect</tt>' keyword, like so:
</p>

<div class="doc_code">
<pre>
call void asm sideeffect "eieio", ""()
</pre>
</div>

<p>TODO: The format of the asm and constraints string still need to be
documented here.  Constraints on what can be done (e.g. duplication, moving, etc
need to be documented).
</p>

</div>

<!-- *********************************************************************** -->
<div class="doc_section"> <a name="instref">Instruction Reference</a> </div>
<!-- *********************************************************************** -->

<div class="doc_text">

<p>The LLVM instruction set consists of several different
classifications of instructions: <a href="#terminators">terminator
instructions</a>, <a href="#binaryops">binary instructions</a>,
<a href="#bitwiseops">bitwise binary instructions</a>, <a
 href="#memoryops">memory instructions</a>, and <a href="#otherops">other
instructions</a>.</p>

</div>

<!-- ======================================================================= -->
<div class="doc_subsection"> <a name="terminators">Terminator
Instructions</a> </div>

<div class="doc_text">

<p>As mentioned <a href="#functionstructure">previously</a>, every
basic block in a program ends with a "Terminator" instruction, which
indicates which block should be executed after the current block is
finished. These terminator instructions typically yield a '<tt>void</tt>'
value: they produce control flow, not values (the one exception being
the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction).</p>
<p>There are six different terminator instructions: the '<a
 href="#i_ret"><tt>ret</tt></a>' instruction, the '<a href="#i_br"><tt>br</tt></a>'
instruction, the '<a href="#i_switch"><tt>switch</tt></a>' instruction,
the '<a href="#i_invoke"><tt>invoke</tt></a>' instruction, the '<a
 href="#i_unwind"><tt>unwind</tt></a>' instruction, and the '<a
 href="#i_unreachable"><tt>unreachable</tt></a>' instruction.</p>

</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection"> <a name="i_ret">'<tt>ret</tt>'
Instruction</a> </div>
<div class="doc_text">
<h5>Syntax:</h5>
<pre>  ret &lt;type&gt; &lt;value&gt;       <i>; Return a value from a non-void function</i>
  ret void                 <i>; Return from void function</i>
</pre>
<h5>Overview:</h5>
<p>The '<tt>ret</tt>' instruction is used to return control flow (and a
value) from a function back to the caller.</p>
<p>There are two forms of the '<tt>ret</tt>' instruction: one that
returns a value and then causes control flow, and one that just causes
control flow to occur.</p>
<h5>Arguments:</h5>
<p>The '<tt>ret</tt>' instruction may return any '<a
 href="#t_firstclass">first class</a>' type.  Notice that a function is
not <a href="#wellformed">well formed</a> if there exists a '<tt>ret</tt>'
instruction inside of the function that returns a value that does not
match the return type of the function.</p>
<h5>Semantics:</h5>
<p>When the '<tt>ret</tt>' instruction is executed, control flow
returns back to the calling function's context.  If the caller is a "<a
 href="#i_call"><tt>call</tt></a>" instruction, execution continues at
the instruction after the call.  If the caller was an "<a
 href="#i_invoke"><tt>invoke</tt></a>" instruction, execution continues
at the beginning of the "normal" destination block.  If the instruction
returns a value, that value shall set the call or invoke instruction's
return value.</p>
<h5>Example:</h5>
<pre>  ret i32 5                       <i>; Return an integer value of 5</i>
  ret void                        <i>; Return from a void function</i>
</pre>
</div>
<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection"> <a name="i_br">'<tt>br</tt>' Instruction</a> </div>
<div class="doc_text">
<h5>Syntax:</h5>
<pre>  br i1 &lt;cond&gt;, label &lt;iftrue&gt;, label &lt;iffalse&gt;<br>  br label &lt;dest&gt;          <i>; Unconditional branch</i>
</pre>
<h5>Overview:</h5>
<p>The '<tt>br</tt>' instruction is used to cause control flow to
transfer to a different basic block in the current function.  There are
two forms of this instruction, corresponding to a conditional branch
and an unconditional branch.</p>
<h5>Arguments:</h5>
<p>The conditional branch form of the '<tt>br</tt>' instruction takes a
single '<tt>i1</tt>' value and two '<tt>label</tt>' values.  The
unconditional form of the '<tt>br</tt>' instruction takes a single 
'<tt>label</tt>' value as a target.</p>
<h5>Semantics:</h5>
<p>Upon execution of a conditional '<tt>br</tt>' instruction, the '<tt>i1</tt>'
argument is evaluated.  If the value is <tt>true</tt>, control flows
to the '<tt>iftrue</tt>' <tt>label</tt> argument.  If "cond" is <tt>false</tt>,
control flows to the '<tt>iffalse</tt>' <tt>label</tt> argument.</p>
<h5>Example:</h5>
<pre>Test:<br>  %cond = <a href="#i_icmp">icmp</a> eq, i32 %a, %b<br>  br i1 %cond, label %IfEqual, label %IfUnequal<br>IfEqual:<br>  <a
 href="#i_ret">ret</a> i32 1<br>IfUnequal:<br>  <a href="#i_ret">ret</a> i32 0<br></pre>
</div>
<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
   <a name="i_switch">'<tt>switch</tt>' Instruction</a>
</div>

<div class="doc_text">
<h5>Syntax:</h5>

<pre>
  switch &lt;intty&gt; &lt;value&gt;, label &lt;defaultdest&gt; [ &lt;intty&gt; &lt;val&gt;, label &lt;dest&gt; ... ]
</pre>

<h5>Overview:</h5>

<p>The '<tt>switch</tt>' instruction is used to transfer control flow to one of
several different places.  It is a generalization of the '<tt>br</tt>'
instruction, allowing a branch to occur to one of many possible
destinations.</p>


<h5>Arguments:</h5>

<p>The '<tt>switch</tt>' instruction uses three parameters: an integer
comparison value '<tt>value</tt>', a default '<tt>label</tt>' destination, and
an array of pairs of comparison value constants and '<tt>label</tt>'s.  The
table is not allowed to contain duplicate constant entries.</p>

<h5>Semantics:</h5>

<p>The <tt>switch</tt> instruction specifies a table of values and
destinations. When the '<tt>switch</tt>' instruction is executed, this
table is searched for the given value.  If the value is found, control flow is
transfered to the corresponding destination; otherwise, control flow is
transfered to the default destination.</p>

<h5>Implementation:</h5>

<p>Depending on properties of the target machine and the particular
<tt>switch</tt> instruction, this instruction may be code generated in different
ways.  For example, it could be generated as a series of chained conditional
branches or with a lookup table.</p>

<h5>Example:</h5>

<pre>
 <i>; Emulate a conditional br instruction</i>
 %Val = <a href="#i_zext">zext</a> i1 %value to i32
 switch i32 %Val, label %truedest [i32 0, label %falsedest ]

 <i>; Emulate an unconditional br instruction</i>
 switch i32 0, label %dest [ ]

 <i>; Implement a jump table:</i>
 switch i32 %val, label %otherwise [ i32 0, label %onzero 
                                      i32 1, label %onone 
                                      i32 2, label %ontwo ]
</pre>
</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
  <a name="i_invoke">'<tt>invoke</tt>' Instruction</a>
</div>

<div class="doc_text">

<h5>Syntax:</h5>

<pre>
  &lt;result&gt; = invoke [<a href="#callingconv">cconv</a>] &lt;ptr to function ty&gt; %&lt;function ptr val&gt;(&lt;function args&gt;) 
                to label &lt;normal label&gt; unwind label &lt;exception label&gt;
</pre>

<h5>Overview:</h5>

<p>The '<tt>invoke</tt>' instruction causes control to transfer to a specified
function, with the possibility of control flow transfer to either the
'<tt>normal</tt>' label or the
'<tt>exception</tt>' label.  If the callee function returns with the
"<tt><a href="#i_ret">ret</a></tt>" instruction, control flow will return to the
"normal" label.  If the callee (or any indirect callees) returns with the "<a
href="#i_unwind"><tt>unwind</tt></a>" instruction, control is interrupted and
continued at the dynamically nearest "exception" label.</p>

<h5>Arguments:</h5>

<p>This instruction requires several arguments:</p>

<ol>
  <li>
    The optional "cconv" marker indicates which <a href="#callingconv">calling
    convention</a> the call should use.  If none is specified, the call defaults
    to using C calling conventions.
  </li>
  <li>'<tt>ptr to function ty</tt>': shall be the signature of the pointer to
  function value being invoked.  In most cases, this is a direct function
  invocation, but indirect <tt>invoke</tt>s are just as possible, branching off
  an arbitrary pointer to function value.
  </li>

  <li>'<tt>function ptr val</tt>': An LLVM value containing a pointer to a
  function to be invoked. </li>

  <li>'<tt>function args</tt>': argument list whose types match the function
  signature argument types.  If the function signature indicates the function
  accepts a variable number of arguments, the extra arguments can be
  specified. </li>

  <li>'<tt>normal label</tt>': the label reached when the called function
  executes a '<tt><a href="#i_ret">ret</a></tt>' instruction. </li>

  <li>'<tt>exception label</tt>': the label reached when a callee returns with
  the <a href="#i_unwind"><tt>unwind</tt></a> instruction. </li>

</ol>

<h5>Semantics:</h5>

<p>This instruction is designed to operate as a standard '<tt><a
href="#i_call">call</a></tt>' instruction in most regards.  The primary
difference is that it establishes an association with a label, which is used by
the runtime library to unwind the stack.</p>

<p>This instruction is used in languages with destructors to ensure that proper
cleanup is performed in the case of either a <tt>longjmp</tt> or a thrown
exception.  Additionally, this is important for implementation of
'<tt>catch</tt>' clauses in high-level languages that support them.</p>

<h5>Example:</h5>
<pre>
  %retval = invoke i32 %Test(i32 15) to label %Continue
              unwind label %TestCleanup              <i>; {i32}:retval set</i>
  %retval = invoke <a href="#callingconv">coldcc</a> i32 %Test(i32 15) to label %Continue
              unwind label %TestCleanup              <i>; {i32}:retval set</i>
</pre>
</div>


<!-- _______________________________________________________________________ -->

<div class="doc_subsubsection"> <a name="i_unwind">'<tt>unwind</tt>'
Instruction</a> </div>

<div class="doc_text">

<h5>Syntax:</h5>
<pre>
  unwind
</pre>

<h5>Overview:</h5>

<p>The '<tt>unwind</tt>' instruction unwinds the stack, continuing control flow
at the first callee in the dynamic call stack which used an <a
href="#i_invoke"><tt>invoke</tt></a> instruction to perform the call.  This is
primarily used to implement exception handling.</p>

<h5>Semantics:</h5>

<p>The '<tt>unwind</tt>' intrinsic causes execution of the current function to
immediately halt.  The dynamic call stack is then searched for the first <a
href="#i_invoke"><tt>invoke</tt></a> instruction on the call stack.  Once found,
execution continues at the "exceptional" destination block specified by the
<tt>invoke</tt> instruction.  If there is no <tt>invoke</tt> instruction in the
dynamic call chain, undefined behavior results.</p>
</div>

<!-- _______________________________________________________________________ -->

<div class="doc_subsubsection"> <a name="i_unreachable">'<tt>unreachable</tt>'
Instruction</a> </div>

<div class="doc_text">

<h5>Syntax:</h5>
<pre>
  unreachable
</pre>

<h5>Overview:</h5>

<p>The '<tt>unreachable</tt>' instruction has no defined semantics.  This
instruction is used to inform the optimizer that a particular portion of the
code is not reachable.  This can be used to indicate that the code after a
no-return function cannot be reached, and other facts.</p>

<h5>Semantics:</h5>

<p>The '<tt>unreachable</tt>' instruction has no defined semantics.</p>
</div>



<!-- ======================================================================= -->
<div class="doc_subsection"> <a name="binaryops">Binary Operations</a> </div>
<div class="doc_text">
<p>Binary operators are used to do most of the computation in a
program.  They require two operands, execute an operation on them, and
produce a single value.  The operands might represent 
multiple data, as is the case with the <a href="#t_vector">vector</a> data type. 
The result value of a binary operator is not
necessarily the same type as its operands.</p>
<p>There are several different binary operators:</p>
</div>
<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection"> <a name="i_add">'<tt>add</tt>'
Instruction</a> </div>
<div class="doc_text">
<h5>Syntax:</h5>
<pre>  &lt;result&gt; = add &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt;   <i>; yields {ty}:result</i>
</pre>
<h5>Overview:</h5>
<p>The '<tt>add</tt>' instruction returns the sum of its two operands.</p>
<h5>Arguments:</h5>
<p>The two arguments to the '<tt>add</tt>' instruction must be either <a
 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a> values.
 This instruction can also take <a href="#t_vector">vector</a> versions of the values.
Both arguments must have identical types.</p>
<h5>Semantics:</h5>
<p>The value produced is the integer or floating point sum of the two
operands.</p>
<h5>Example:</h5>
<pre>  &lt;result&gt; = add i32 4, %var          <i>; yields {i32}:result = 4 + %var</i>
</pre>
</div>
<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection"> <a name="i_sub">'<tt>sub</tt>'
Instruction</a> </div>
<div class="doc_text">
<h5>Syntax:</h5>
<pre>  &lt;result&gt; = sub &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt;   <i>; yields {ty}:result</i>
</pre>
<h5>Overview:</h5>
<p>The '<tt>sub</tt>' instruction returns the difference of its two
operands.</p>
<p>Note that the '<tt>sub</tt>' instruction is used to represent the '<tt>neg</tt>'
instruction present in most other intermediate representations.</p>
<h5>Arguments:</h5>
<p>The two arguments to the '<tt>sub</tt>' instruction must be either <a
 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
values. 
This instruction can also take <a href="#t_vector">vector</a> versions of the values.
Both arguments must have identical types.</p>
<h5>Semantics:</h5>
<p>The value produced is the integer or floating point difference of
the two operands.</p>
<h5>Example:</h5>
<pre>
  &lt;result&gt; = sub i32 4, %var          <i>; yields {i32}:result = 4 - %var</i>
  &lt;result&gt; = sub i32 0, %val          <i>; yields {i32}:result = -%var</i>
</pre>
</div>
<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection"> <a name="i_mul">'<tt>mul</tt>'
Instruction</a> </div>
<div class="doc_text">
<h5>Syntax:</h5>
<pre>  &lt;result&gt; = mul &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt;   <i>; yields {ty}:result</i>
</pre>
<h5>Overview:</h5>
<p>The  '<tt>mul</tt>' instruction returns the product of its two
operands.</p>
<h5>Arguments:</h5>
<p>The two arguments to the '<tt>mul</tt>' instruction must be either <a
 href="#t_integer">integer</a> or <a href="#t_floating">floating point</a>
values. 
This instruction can also take <a href="#t_vector">vector</a> versions of the values.
Both arguments must have identical types.</p>
<h5>Semantics:</h5>
<p>The value produced is the integer or floating point product of the
two operands.</p>
<p>Because the operands are the same width, the result of an integer
multiplication is the same whether the operands should be deemed unsigned or
signed.</p>
<h5>Example:</h5>
<pre>  &lt;result&gt; = mul i32 4, %var          <i>; yields {i32}:result = 4 * %var</i>
</pre>
</div>
<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection"> <a name="i_udiv">'<tt>udiv</tt>' Instruction
</a></div>
<div class="doc_text">
<h5>Syntax:</h5>
<pre>  &lt;result&gt; = udiv &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt;   <i>; yields {ty}:result</i>
</pre>
<h5>Overview:</h5>
<p>The '<tt>udiv</tt>' instruction returns the quotient of its two
operands.</p>
<h5>Arguments:</h5>
<p>The two arguments to the '<tt>udiv</tt>' instruction must be 
<a href="#t_integer">integer</a> values. Both arguments must have identical 
types. This instruction can also take <a href="#t_vector">vector</a> versions 
of the values in which case the elements must be integers.</p>
<h5>Semantics:</h5>
<p>The value produced is the unsigned integer quotient of the two operands. This
instruction always performs an unsigned division operation, regardless of 
whether the arguments are unsigned or not.</p>
<h5>Example:</h5>
<pre>  &lt;result&gt; = udiv i32 4, %var          <i>; yields {i32}:result = 4 / %var</i>
</pre>
</div>
<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection"> <a name="i_sdiv">'<tt>sdiv</tt>' Instruction
</a> </div>
<div class="doc_text">
<h5>Syntax:</h5>
<pre>  &lt;result&gt; = sdiv &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt;   <i>; yields {ty}:result</i>
</pre>
<h5>Overview:</h5>
<p>The '<tt>sdiv</tt>' instruction returns the quotient of its two
operands.</p>
<h5>Arguments:</h5>
<p>The two arguments to the '<tt>sdiv</tt>' instruction must be
<a href="#t_integer">integer</a> values.  Both arguments must have identical 
types. This instruction can also take <a href="#t_vector">vector</a> versions 
of the values in which case the elements must be integers.</p>
<h5>Semantics:</h5>
<p>The value produced is the signed integer quotient of the two operands. This
instruction always performs a signed division operation, regardless of whether
the arguments are signed or not.</p>
<h5>Example:</h5>
<pre>  &lt;result&gt; = sdiv i32 4, %var          <i>; yields {i32}:result = 4 / %var</i>
</pre>
</div>
<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection"> <a name="i_fdiv">'<tt>fdiv</tt>'
Instruction</a> </div>
<div class="doc_text">
<h5>Syntax:</h5>
<pre>  &lt;result&gt; = fdiv &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt;   <i>; yields {ty}:result</i>
</pre>
<h5>Overview:</h5>
<p>The '<tt>fdiv</tt>' instruction returns the quotient of its two
operands.</p>
<h5>Arguments:</h5>
<p>The two arguments to the '<tt>fdiv</tt>' instruction must be
<a href="#t_floating">floating point</a> values.  Both arguments must have
identical types.  This instruction can also take <a href="#t_vector">vector</a>
versions of floating point values.</p>
<h5>Semantics:</h5>
<p>The value produced is the floating point quotient of the two operands.</p>
<h5>Example:</h5>
<pre>  &lt;result&gt; = fdiv float 4.0, %var          <i>; yields {float}:result = 4.0 / %var</i>
</pre>
</div>
<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection"> <a name="i_urem">'<tt>urem</tt>' Instruction</a>
</div>
<div class="doc_text">
<h5>Syntax:</h5>
<pre>  &lt;result&gt; = urem &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt;   <i>; yields {ty}:result</i>
</pre>
<h5>Overview:</h5>
<p>The '<tt>urem</tt>' instruction returns the remainder from the
unsigned division of its two arguments.</p>
<h5>Arguments:</h5>
<p>The two arguments to the '<tt>urem</tt>' instruction must be
<a href="#t_integer">integer</a> values. Both arguments must have identical
types.</p>
<h5>Semantics:</h5>
<p>This instruction returns the unsigned integer <i>remainder</i> of a division.
This instruction always performs an unsigned division to get the remainder,
regardless of whether the arguments are unsigned or not.</p>
<h5>Example:</h5>
<pre>  &lt;result&gt; = urem i32 4, %var          <i>; yields {i32}:result = 4 % %var</i>
</pre>

</div>
<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection"> <a name="i_srem">'<tt>srem</tt>'
Instruction</a> </div>
<div class="doc_text">
<h5>Syntax:</h5>
<pre>  &lt;result&gt; = srem &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt;   <i>; yields {ty}:result</i>
</pre>
<h5>Overview:</h5>
<p>The '<tt>srem</tt>' instruction returns the remainder from the
signed division of its two operands.</p>
<h5>Arguments:</h5>
<p>The two arguments to the '<tt>srem</tt>' instruction must be 
<a href="#t_integer">integer</a> values.  Both arguments must have identical 
types.</p>
<h5>Semantics:</h5>
<p>This instruction returns the <i>remainder</i> of a division (where the result
has the same sign as the dividend, <tt>var1</tt>), not the <i>modulo</i> 
operator (where the result has the same sign as the divisor, <tt>var2</tt>) of 
a value.  For more information about the difference, see <a
 href="http://mathforum.org/dr.math/problems/anne.4.28.99.html">The
Math Forum</a>. For a table of how this is implemented in various languages,
please see <a href="http://en.wikipedia.org/wiki/Modulo_operation">
Wikipedia: modulo operation</a>.</p>
<h5>Example:</h5>
<pre>  &lt;result&gt; = srem i32 4, %var          <i>; yields {i32}:result = 4 % %var</i>
</pre>

</div>
<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection"> <a name="i_frem">'<tt>frem</tt>'
Instruction</a> </div>
<div class="doc_text">
<h5>Syntax:</h5>
<pre>  &lt;result&gt; = frem &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt;   <i>; yields {ty}:result</i>
</pre>
<h5>Overview:</h5>
<p>The '<tt>frem</tt>' instruction returns the remainder from the
division of its two operands.</p>
<h5>Arguments:</h5>
<p>The two arguments to the '<tt>frem</tt>' instruction must be
<a href="#t_floating">floating point</a> values.  Both arguments must have 
identical types.</p>
<h5>Semantics:</h5>
<p>This instruction returns the <i>remainder</i> of a division.</p>
<h5>Example:</h5>
<pre>  &lt;result&gt; = frem float 4.0, %var          <i>; yields {float}:result = 4.0 % %var</i>
</pre>
</div>

<!-- ======================================================================= -->
<div class="doc_subsection"> <a name="bitwiseops">Bitwise Binary
Operations</a> </div>
<div class="doc_text">
<p>Bitwise binary operators are used to do various forms of
bit-twiddling in a program.  They are generally very efficient
instructions and can commonly be strength reduced from other
instructions.  They require two operands, execute an operation on them,
and produce a single value.  The resulting value of the bitwise binary
operators is always the same type as its first operand.</p>
</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection"> <a name="i_shl">'<tt>shl</tt>'
Instruction</a> </div>
<div class="doc_text">
<h5>Syntax:</h5>
<pre>  &lt;result&gt; = shl &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt;   <i>; yields {ty}:result</i>
</pre>
<h5>Overview:</h5>
<p>The '<tt>shl</tt>' instruction returns the first operand shifted to
the left a specified number of bits.</p>
<h5>Arguments:</h5>
<p>Both arguments to the '<tt>shl</tt>' instruction must be the same <a
 href="#t_integer">integer</a> type.</p>
<h5>Semantics:</h5>
<p>The value produced is <tt>var1</tt> * 2<sup><tt>var2</tt></sup>.</p>
<h5>Example:</h5><pre>
  &lt;result&gt; = shl i32 4, %var   <i>; yields {i32}: 4 &lt;&lt; %var</i>
  &lt;result&gt; = shl i32 4, 2      <i>; yields {i32}: 16</i>
  &lt;result&gt; = shl i32 1, 10     <i>; yields {i32}: 1024</i>
</pre>
</div>
<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection"> <a name="i_lshr">'<tt>lshr</tt>'
Instruction</a> </div>
<div class="doc_text">
<h5>Syntax:</h5>
<pre>  &lt;result&gt; = lshr &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt;   <i>; yields {ty}:result</i>
</pre>

<h5>Overview:</h5>
<p>The '<tt>lshr</tt>' instruction (logical shift right) returns the first 
operand shifted to the right a specified number of bits with zero fill.</p>

<h5>Arguments:</h5>
<p>Both arguments to the '<tt>lshr</tt>' instruction must be the same 
<a href="#t_integer">integer</a> type.</p>

<h5>Semantics:</h5>
<p>This instruction always performs a logical shift right operation. The most
significant bits of the result will be filled with zero bits after the 
shift.</p>

<h5>Example:</h5>
<pre>
  &lt;result&gt; = lshr i32 4, 1   <i>; yields {i32}:result = 2</i>
  &lt;result&gt; = lshr i32 4, 2   <i>; yields {i32}:result = 1</i>
  &lt;result&gt; = lshr i8  4, 3   <i>; yields {i8}:result = 0</i>
  &lt;result&gt; = lshr i8 -2, 1   <i>; yields {i8}:result = 0x7FFFFFFF </i>
</pre>
</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection"> <a name="i_ashr">'<tt>ashr</tt>'
Instruction</a> </div>
<div class="doc_text">

<h5>Syntax:</h5>
<pre>  &lt;result&gt; = ashr &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt;   <i>; yields {ty}:result</i>
</pre>

<h5>Overview:</h5>
<p>The '<tt>ashr</tt>' instruction (arithmetic shift right) returns the first 
operand shifted to the right a specified number of bits with sign extension.</p>

<h5>Arguments:</h5>
<p>Both arguments to the '<tt>ashr</tt>' instruction must be the same 
<a href="#t_integer">integer</a> type.</p>

<h5>Semantics:</h5>
<p>This instruction always performs an arithmetic shift right operation, 
The most significant bits of the result will be filled with the sign bit 
of <tt>var1</tt>.</p>

<h5>Example:</h5>
<pre>
  &lt;result&gt; = ashr i32 4, 1   <i>; yields {i32}:result = 2</i>
  &lt;result&gt; = ashr i32 4, 2   <i>; yields {i32}:result = 1</i>
  &lt;result&gt; = ashr i8  4, 3   <i>; yields {i8}:result = 0</i>
  &lt;result&gt; = ashr i8 -2, 1   <i>; yields {i8}:result = -1</i>
</pre>
</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection"> <a name="i_and">'<tt>and</tt>'
Instruction</a> </div>
<div class="doc_text">
<h5>Syntax:</h5>
<pre>  &lt;result&gt; = and &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt;   <i>; yields {ty}:result</i>
</pre>
<h5>Overview:</h5>
<p>The '<tt>and</tt>' instruction returns the bitwise logical and of
its two operands.</p>
<h5>Arguments:</h5>
<p>The two arguments to the '<tt>and</tt>' instruction must be <a
 href="#t_integer">integer</a> values.  Both arguments must have
identical types.</p>
<h5>Semantics:</h5>
<p>The truth table used for the '<tt>and</tt>' instruction is:</p>
<p> </p>
<div style="align: center">
<table border="1" cellspacing="0" cellpadding="4">
  <tbody>
    <tr>
      <td>In0</td>
      <td>In1</td>
      <td>Out</td>
    </tr>
    <tr>
      <td>0</td>
      <td>0</td>
      <td>0</td>
    </tr>
    <tr>
      <td>0</td>
      <td>1</td>
      <td>0</td>
    </tr>
    <tr>
      <td>1</td>
      <td>0</td>
      <td>0</td>
    </tr>
    <tr>
      <td>1</td>
      <td>1</td>
      <td>1</td>
    </tr>
  </tbody>
</table>
</div>
<h5>Example:</h5>
<pre>  &lt;result&gt; = and i32 4, %var         <i>; yields {i32}:result = 4 &amp; %var</i>
  &lt;result&gt; = and i32 15, 40          <i>; yields {i32}:result = 8</i>
  &lt;result&gt; = and i32 4, 8            <i>; yields {i32}:result = 0</i>
</pre>
</div>
<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection"> <a name="i_or">'<tt>or</tt>' Instruction</a> </div>
<div class="doc_text">
<h5>Syntax:</h5>
<pre>  &lt;result&gt; = or &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt;   <i>; yields {ty}:result</i>
</pre>
<h5>Overview:</h5>
<p>The '<tt>or</tt>' instruction returns the bitwise logical inclusive
or of its two operands.</p>
<h5>Arguments:</h5>
<p>The two arguments to the '<tt>or</tt>' instruction must be <a
 href="#t_integer">integer</a> values.  Both arguments must have
identical types.</p>
<h5>Semantics:</h5>
<p>The truth table used for the '<tt>or</tt>' instruction is:</p>
<p> </p>
<div style="align: center">
<table border="1" cellspacing="0" cellpadding="4">
  <tbody>
    <tr>
      <td>In0</td>
      <td>In1</td>
      <td>Out</td>
    </tr>
    <tr>
      <td>0</td>
      <td>0</td>
      <td>0</td>
    </tr>
    <tr>
      <td>0</td>
      <td>1</td>
      <td>1</td>
    </tr>
    <tr>
      <td>1</td>
      <td>0</td>
      <td>1</td>
    </tr>
    <tr>
      <td>1</td>
      <td>1</td>
      <td>1</td>
    </tr>
  </tbody>
</table>
</div>
<h5>Example:</h5>
<pre>  &lt;result&gt; = or i32 4, %var         <i>; yields {i32}:result = 4 | %var</i>
  &lt;result&gt; = or i32 15, 40          <i>; yields {i32}:result = 47</i>
  &lt;result&gt; = or i32 4, 8            <i>; yields {i32}:result = 12</i>
</pre>
</div>
<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection"> <a name="i_xor">'<tt>xor</tt>'
Instruction</a> </div>
<div class="doc_text">
<h5>Syntax:</h5>
<pre>  &lt;result&gt; = xor &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt;   <i>; yields {ty}:result</i>
</pre>
<h5>Overview:</h5>
<p>The '<tt>xor</tt>' instruction returns the bitwise logical exclusive
or of its two operands.  The <tt>xor</tt> is used to implement the
"one's complement" operation, which is the "~" operator in C.</p>
<h5>Arguments:</h5>
<p>The two arguments to the '<tt>xor</tt>' instruction must be <a
 href="#t_integer">integer</a> values.  Both arguments must have
identical types.</p>
<h5>Semantics:</h5>
<p>The truth table used for the '<tt>xor</tt>' instruction is:</p>
<p> </p>
<div style="align: center">
<table border="1" cellspacing="0" cellpadding="4">
  <tbody>
    <tr>
      <td>In0</td>
      <td>In1</td>
      <td>Out</td>
    </tr>
    <tr>
      <td>0</td>
      <td>0</td>
      <td>0</td>
    </tr>
    <tr>
      <td>0</td>
      <td>1</td>
      <td>1</td>
    </tr>
    <tr>
      <td>1</td>
      <td>0</td>
      <td>1</td>
    </tr>
    <tr>
      <td>1</td>
      <td>1</td>
      <td>0</td>
    </tr>
  </tbody>
</table>
</div>
<p> </p>
<h5>Example:</h5>
<pre>  &lt;result&gt; = xor i32 4, %var         <i>; yields {i32}:result = 4 ^ %var</i>
  &lt;result&gt; = xor i32 15, 40          <i>; yields {i32}:result = 39</i>
  &lt;result&gt; = xor i32 4, 8            <i>; yields {i32}:result = 12</i>
  &lt;result&gt; = xor i32 %V, -1          <i>; yields {i32}:result = ~%V</i>
</pre>
</div>

<!-- ======================================================================= -->
<div class="doc_subsection"> 
  <a name="vectorops">Vector Operations</a>
</div>

<div class="doc_text">

<p>LLVM supports several instructions to represent vector operations in a
target-independent manner.  These instructions cover the element-access and
vector-specific operations needed to process vectors effectively.  While LLVM
does directly support these vector operations, many sophisticated algorithms
will want to use target-specific intrinsics to take full advantage of a specific
target.</p>

</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
   <a name="i_extractelement">'<tt>extractelement</tt>' Instruction</a>
</div>

<div class="doc_text">

<h5>Syntax:</h5>

<pre>
  &lt;result&gt; = extractelement &lt;n x &lt;ty&gt;&gt; &lt;val&gt;, i32 &lt;idx&gt;    <i>; yields &lt;ty&gt;</i>
</pre>

<h5>Overview:</h5>

<p>
The '<tt>extractelement</tt>' instruction extracts a single scalar
element from a vector at a specified index.
</p>


<h5>Arguments:</h5>

<p>
The first operand of an '<tt>extractelement</tt>' instruction is a
value of <a href="#t_vector">vector</a> type.  The second operand is
an index indicating the position from which to extract the element.
The index may be a variable.</p>

<h5>Semantics:</h5>

<p>
The result is a scalar of the same type as the element type of
<tt>val</tt>.  Its value is the value at position <tt>idx</tt> of
<tt>val</tt>.  If <tt>idx</tt> exceeds the length of <tt>val</tt>, the
results are undefined.
</p>

<h5>Example:</h5>

<pre>
  %result = extractelement &lt;4 x i32&gt; %vec, i32 0    <i>; yields i32</i>
</pre>
</div>


<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
   <a name="i_insertelement">'<tt>insertelement</tt>' Instruction</a>
</div>

<div class="doc_text">

<h5>Syntax:</h5>

<pre>
  &lt;result&gt; = insertelement &lt;n x &lt;ty&gt;&gt; &lt;val&gt;, &lt;ty&gt; &lt;elt&gt, i32 &lt;idx&gt;    <i>; yields &lt;n x &lt;ty&gt;&gt;</i>
</pre>

<h5>Overview:</h5>

<p>
The '<tt>insertelement</tt>' instruction inserts a scalar
element into a vector at a specified index.
</p>


<h5>Arguments:</h5>

<p>
The first operand of an '<tt>insertelement</tt>' instruction is a
value of <a href="#t_vector">vector</a> type.  The second operand is a
scalar value whose type must equal the element type of the first
operand.  The third operand is an index indicating the position at
which to insert the value.  The index may be a variable.</p>

<h5>Semantics:</h5>

<p>
The result is a vector of the same type as <tt>val</tt>.  Its
element values are those of <tt>val</tt> except at position
<tt>idx</tt>, where it gets the value <tt>elt</tt>.  If <tt>idx</tt>
exceeds the length of <tt>val</tt>, the results are undefined.
</p>

<h5>Example:</h5>

<pre>
  %result = insertelement &lt;4 x i32&gt; %vec, i32 1, i32 0    <i>; yields &lt;4 x i32&gt;</i>
</pre>
</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
   <a name="i_shufflevector">'<tt>shufflevector</tt>' Instruction</a>
</div>

<div class="doc_text">

<h5>Syntax:</h5>

<pre>
  &lt;result&gt; = shufflevector &lt;n x &lt;ty&gt;&gt; &lt;v1&gt;, &lt;n x &lt;ty&gt;&gt; &lt;v2&gt;, &lt;n x i32&gt; &lt;mask&gt;    <i>; yields &lt;n x &lt;ty&gt;&gt;</i>
</pre>

<h5>Overview:</h5>

<p>
The '<tt>shufflevector</tt>' instruction constructs a permutation of elements
from two input vectors, returning a vector of the same type.
</p>

<h5>Arguments:</h5>

<p>
The first two operands of a '<tt>shufflevector</tt>' instruction are vectors
with types that match each other and types that match the result of the
instruction.  The third argument is a shuffle mask, which has the same number
of elements as the other vector type, but whose element type is always 'i32'.
</p>

<p>
The shuffle mask operand is required to be a constant vector with either
constant integer or undef values.
</p>

<h5>Semantics:</h5>

<p>
The elements of the two input vectors are numbered from left to right across
both of the vectors.  The shuffle mask operand specifies, for each element of
the result vector, which element of the two input registers the result element
gets.  The element selector may be undef (meaning "don't care") and the second
operand may be undef if performing a shuffle from only one vector.
</p>

<h5>Example:</h5>

<pre>
  %result = shufflevector &lt;4 x i32&gt; %v1, &lt;4 x i32&gt; %v2, 
                          &lt;4 x i32&gt; &lt;i32 0, i32 4, i32 1, i32 5&gt;  <i>; yields &lt;4 x i32&gt;</i>
  %result = shufflevector &lt;4 x i32&gt; %v1, &lt;4 x i32&gt; undef, 
                          &lt;4 x i32&gt; &lt;i32 0, i32 1, i32 2, i32 3&gt;  <i>; yields &lt;4 x i32&gt;</i> - Identity shuffle.
</pre>
</div>


<!-- ======================================================================= -->
<div class="doc_subsection"> 
  <a name="memoryops">Memory Access and Addressing Operations</a>
</div>

<div class="doc_text">

<p>A key design point of an SSA-based representation is how it
represents memory.  In LLVM, no memory locations are in SSA form, which
makes things very simple.  This section describes how to read, write,
allocate, and free memory in LLVM.</p>

</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
  <a name="i_malloc">'<tt>malloc</tt>' Instruction</a>
</div>

<div class="doc_text">

<h5>Syntax:</h5>

<pre>
  &lt;result&gt; = malloc &lt;type&gt;[, i32 &lt;NumElements&gt;][, align &lt;alignment&gt;]     <i>; yields {type*}:result</i>
</pre>

<h5>Overview:</h5>

<p>The '<tt>malloc</tt>' instruction allocates memory from the system
heap and returns a pointer to it.</p>

<h5>Arguments:</h5>

<p>The '<tt>malloc</tt>' instruction allocates
<tt>sizeof(&lt;type&gt;)*NumElements</tt>
bytes of memory from the operating system and returns a pointer of the
appropriate type to the program.  If "NumElements" is specified, it is the
number of elements allocated.  If an alignment is specified, the value result
of the allocation is guaranteed to be aligned to at least that boundary.  If
not specified, or if zero, the target can choose to align the allocation on any
convenient boundary.</p>

<p>'<tt>type</tt>' must be a sized type.</p>

<h5>Semantics:</h5>

<p>Memory is allocated using the system "<tt>malloc</tt>" function, and
a pointer is returned.</p>

<h5>Example:</h5>

<pre>
  %array  = malloc [4 x i8 ]                    <i>; yields {[%4 x i8]*}:array</i>

  %size   = <a href="#i_add">add</a> i32 2, 2                        <i>; yields {i32}:size = i32 4</i>
  %array1 = malloc i8, i32 4                    <i>; yields {i8*}:array1</i>
  %array2 = malloc [12 x i8], i32 %size         <i>; yields {[12 x i8]*}:array2</i>
  %array3 = malloc i32, i32 4, align 1024       <i>; yields {i32*}:array3</i>
  %array4 = malloc i32, align 1024              <i>; yields {i32*}:array4</i>
</pre>
</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
  <a name="i_free">'<tt>free</tt>' Instruction</a>
</div>

<div class="doc_text">

<h5>Syntax:</h5>

<pre>
  free &lt;type&gt; &lt;value&gt;                              <i>; yields {void}</i>
</pre>

<h5>Overview:</h5>

<p>The '<tt>free</tt>' instruction returns memory back to the unused
memory heap to be reallocated in the future.</p>

<h5>Arguments:</h5>

<p>'<tt>value</tt>' shall be a pointer value that points to a value
that was allocated with the '<tt><a href="#i_malloc">malloc</a></tt>'
instruction.</p>

<h5>Semantics:</h5>

<p>Access to the memory pointed to by the pointer is no longer defined
after this instruction executes.</p>

<h5>Example:</h5>

<pre>
  %array  = <a href="#i_malloc">malloc</a> [4 x i8]                    <i>; yields {[4 x i8]*}:array</i>
            free   [4 x i8]* %array
</pre>
</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
  <a name="i_alloca">'<tt>alloca</tt>' Instruction</a>
</div>

<div class="doc_text">

<h5>Syntax:</h5>

<pre>
  &lt;result&gt; = alloca &lt;type&gt;[, i32 &lt;NumElements&gt;][, align &lt;alignment&gt;]     <i>; yields {type*}:result</i>
</pre>

<h5>Overview:</h5>

<p>The '<tt>alloca</tt>' instruction allocates memory on the stack frame of the
currently executing function, to be automatically released when this function
returns to its caller.</p>

<h5>Arguments:</h5>

<p>The '<tt>alloca</tt>' instruction allocates <tt>sizeof(&lt;type&gt;)*NumElements</tt>
bytes of memory on the runtime stack, returning a pointer of the
appropriate type to the program.    If "NumElements" is specified, it is the
number of elements allocated.  If an alignment is specified, the value result
of the allocation is guaranteed to be aligned to at least that boundary.  If
not specified, or if zero, the target can choose to align the allocation on any
convenient boundary.</p>

<p>'<tt>type</tt>' may be any sized type.</p>

<h5>Semantics:</h5>

<p>Memory is allocated; a pointer is returned.  '<tt>alloca</tt>'d
memory is automatically released when the function returns.  The '<tt>alloca</tt>'
instruction is commonly used to represent automatic variables that must
have an address available.  When the function returns (either with the <tt><a
 href="#i_ret">ret</a></tt> or <tt><a href="#i_unwind">unwind</a></tt>
instructions), the memory is reclaimed.</p>

<h5>Example:</h5>

<pre>
  %ptr = alloca i32                              <i>; yields {i32*}:ptr</i>
  %ptr = alloca i32, i32 4                       <i>; yields {i32*}:ptr</i>
  %ptr = alloca i32, i32 4, align 1024           <i>; yields {i32*}:ptr</i>
  %ptr = alloca i32, align 1024                  <i>; yields {i32*}:ptr</i>
</pre>
</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection"> <a name="i_load">'<tt>load</tt>'
Instruction</a> </div>
<div class="doc_text">
<h5>Syntax:</h5>
<pre>  &lt;result&gt; = load &lt;ty&gt;* &lt;pointer&gt;[, align &lt;alignment&gt;]<br>  &lt;result&gt; = volatile load &lt;ty&gt;* &lt;pointer&gt;[, align &lt;alignment&gt;]<br></pre>
<h5>Overview:</h5>
<p>The '<tt>load</tt>' instruction is used to read from memory.</p>
<h5>Arguments:</h5>
<p>The argument to the '<tt>load</tt>' instruction specifies the memory
address from which to load.  The pointer must point to a <a
 href="#t_firstclass">first class</a> type.  If the <tt>load</tt> is
marked as <tt>volatile</tt>, then the optimizer is not allowed to modify
the number or order of execution of this <tt>load</tt> with other
volatile <tt>load</tt> and <tt><a href="#i_store">store</a></tt>
instructions. </p>
<h5>Semantics:</h5>
<p>The location of memory pointed to is loaded.</p>
<h5>Examples:</h5>
<pre>  %ptr = <a href="#i_alloca">alloca</a> i32                               <i>; yields {i32*}:ptr</i>
  <a
 href="#i_store">store</a> i32 3, i32* %ptr                          <i>; yields {void}</i>
  %val = load i32* %ptr                           <i>; yields {i32}:val = i32 3</i>
</pre>
</div>
<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection"> <a name="i_store">'<tt>store</tt>'
Instruction</a> </div>
<div class="doc_text">
<h5>Syntax:</h5>
<pre>  store &lt;ty&gt; &lt;value&gt;, &lt;ty&gt;* &lt;pointer&gt;[, align &lt;alignment&gt;]                   <i>; yields {void}</i>
  volatile store &lt;ty&gt; &lt;value&gt;, &lt;ty&gt;* &lt;pointer&gt;[, align &lt;alignment&gt;]          <i>; yields {void}</i>
</pre>
<h5>Overview:</h5>
<p>The '<tt>store</tt>' instruction is used to write to memory.</p>
<h5>Arguments:</h5>
<p>There are two arguments to the '<tt>store</tt>' instruction: a value
to store and an address at which to store it.  The type of the '<tt>&lt;pointer&gt;</tt>'
operand must be a pointer to the type of the '<tt>&lt;value&gt;</tt>'
operand. If the <tt>store</tt> is marked as <tt>volatile</tt>, then the
optimizer is not allowed to modify the number or order of execution of
this <tt>store</tt> with other volatile <tt>load</tt> and <tt><a
 href="#i_store">store</a></tt> instructions.</p>
<h5>Semantics:</h5>
<p>The contents of memory are updated to contain '<tt>&lt;value&gt;</tt>'
at the location specified by the '<tt>&lt;pointer&gt;</tt>' operand.</p>
<h5>Example:</h5>
<pre>  %ptr = <a href="#i_alloca">alloca</a> i32                               <i>; yields {i32*}:ptr</i>
  <a
 href="#i_store">store</a> i32 3, i32* %ptr                          <i>; yields {void}</i>
  %val = load i32* %ptr                           <i>; yields {i32}:val = i32 3</i>
</pre>
</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
   <a name="i_getelementptr">'<tt>getelementptr</tt>' Instruction</a>
</div>

<div class="doc_text">
<h5>Syntax:</h5>
<pre>
  &lt;result&gt; = getelementptr &lt;ty&gt;* &lt;ptrval&gt;{, &lt;ty&gt; &lt;idx&gt;}*
</pre>

<h5>Overview:</h5>

<p>
The '<tt>getelementptr</tt>' instruction is used to get the address of a
subelement of an aggregate data structure.</p>

<h5>Arguments:</h5>

<p>This instruction takes a list of integer operands that indicate what
elements of the aggregate object to index to.  The actual types of the arguments
provided depend on the type of the first pointer argument.  The
'<tt>getelementptr</tt>' instruction is used to index down through the type
levels of a structure or to a specific index in an array.  When indexing into a
structure, only <tt>i32</tt> integer constants are allowed.  When indexing 
into an array or pointer, only integers of 32 or 64 bits are allowed, and will 
be sign extended to 64-bit values.</p>

<p>For example, let's consider a C code fragment and how it gets
compiled to LLVM:</p>

<div class="doc_code">
<pre>
struct RT {
  char A;
  int B[10][20];
  char C;
};
struct ST {
  int X;
  double Y;
  struct RT Z;
};

int *foo(struct ST *s) {
  return &amp;s[1].Z.B[5][13];
}
</pre>
</div>

<p>The LLVM code generated by the GCC frontend is:</p>

<div class="doc_code">
<pre>
%RT = type { i8 , [10 x [20 x i32]], i8  }
%ST = type { i32, double, %RT }

define i32* %foo(%ST* %s) {
entry:
  %reg = getelementptr %ST* %s, i32 1, i32 2, i32 1, i32 5, i32 13
  ret i32* %reg
}
</pre>
</div>

<h5>Semantics:</h5>

<p>The index types specified for the '<tt>getelementptr</tt>' instruction depend
on the pointer type that is being indexed into. <a href="#t_pointer">Pointer</a>
and <a href="#t_array">array</a> types can use a 32-bit or 64-bit
<a href="#t_integer">integer</a> type but the value will always be sign extended
to 64-bits.  <a href="#t_struct">Structure</a> types require <tt>i32</tt>
<b>constants</b>.</p>

<p>In the example above, the first index is indexing into the '<tt>%ST*</tt>'
type, which is a pointer, yielding a '<tt>%ST</tt>' = '<tt>{ i32, double, %RT
}</tt>' type, a structure.  The second index indexes into the third element of
the structure, yielding a '<tt>%RT</tt>' = '<tt>{ i8 , [10 x [20 x i32]],
i8  }</tt>' type, another structure.  The third index indexes into the second
element of the structure, yielding a '<tt>[10 x [20 x i32]]</tt>' type, an
array.  The two dimensions of the array are subscripted into, yielding an
'<tt>i32</tt>' type.  The '<tt>getelementptr</tt>' instruction returns a pointer
to this element, thus computing a value of '<tt>i32*</tt>' type.</p>

<p>Note that it is perfectly legal to index partially through a
structure, returning a pointer to an inner element.  Because of this,
the LLVM code for the given testcase is equivalent to:</p>

<pre>
  define i32* %foo(%ST* %s) {
    %t1 = getelementptr %ST* %s, i32 1                        <i>; yields %ST*:%t1</i>
    %t2 = getelementptr %ST* %t1, i32 0, i32 2                <i>; yields %RT*:%t2</i>
    %t3 = getelementptr %RT* %t2, i32 0, i32 1                <i>; yields [10 x [20 x i32]]*:%t3</i>
    %t4 = getelementptr [10 x [20 x i32]]* %t3, i32 0, i32 5  <i>; yields [20 x i32]*:%t4</i>
    %t5 = getelementptr [20 x i32]* %t4, i32 0, i32 13        <i>; yields i32*:%t5</i>
    ret i32* %t5
  }
</pre>

<p>Note that it is undefined to access an array out of bounds: array and 
pointer indexes must always be within the defined bounds of the array type.
The one exception for this rules is zero length arrays.  These arrays are
defined to be accessible as variable length arrays, which requires access
beyond the zero'th element.</p>

<p>The getelementptr instruction is often confusing.  For some more insight
into how it works, see <a href="GetElementPtr.html">the getelementptr 
FAQ</a>.</p>

<h5>Example:</h5>

<pre>
    <i>; yields [12 x i8]*:aptr</i>
    %aptr = getelementptr {i32, [12 x i8]}* %sptr, i64 0, i32 1
</pre>
</div>

<!-- ======================================================================= -->
<div class="doc_subsection"> <a name="convertops">Conversion Operations</a>
</div>
<div class="doc_text">
<p>The instructions in this category are the conversion instructions (casting)
which all take a single operand and a type. They perform various bit conversions
on the operand.</p>
</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
   <a name="i_trunc">'<tt>trunc .. to</tt>' Instruction</a>
</div>
<div class="doc_text">

<h5>Syntax:</h5>
<pre>
  &lt;result&gt; = trunc &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt;             <i>; yields ty2</i>
</pre>

<h5>Overview:</h5>
<p>
The '<tt>trunc</tt>' instruction truncates its operand to the type <tt>ty2</tt>.
</p>

<h5>Arguments:</h5>
<p>
The '<tt>trunc</tt>' instruction takes a <tt>value</tt> to trunc, which must 
be an <a href="#t_integer">integer</a> type, and a type that specifies the size 
and type of the result, which must be an <a href="#t_integer">integer</a> 
type. The bit size of <tt>value</tt> must be larger than the bit size of 
<tt>ty2</tt>. Equal sized types are not allowed.</p>

<h5>Semantics:</h5>
<p>
The '<tt>trunc</tt>' instruction truncates the high order bits in <tt>value</tt>
and converts the remaining bits to <tt>ty2</tt>. Since the source size must be
larger than the destination size, <tt>trunc</tt> cannot be a <i>no-op cast</i>.
It will always truncate bits.</p>

<h5>Example:</h5>
<pre>
  %X = trunc i32 257 to i8              <i>; yields i8:1</i>
  %Y = trunc i32 123 to i1              <i>; yields i1:true</i>
  %Y = trunc i32 122 to i1              <i>; yields i1:false</i>
</pre>
</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
   <a name="i_zext">'<tt>zext .. to</tt>' Instruction</a>
</div>
<div class="doc_text">

<h5>Syntax:</h5>
<pre>
  &lt;result&gt; = zext &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt;             <i>; yields ty2</i>
</pre>

<h5>Overview:</h5>
<p>The '<tt>zext</tt>' instruction zero extends its operand to type 
<tt>ty2</tt>.</p>


<h5>Arguments:</h5>
<p>The '<tt>zext</tt>' instruction takes a value to cast, which must be of 
<a href="#t_integer">integer</a> type, and a type to cast it to, which must
also be of <a href="#t_integer">integer</a> type. The bit size of the
<tt>value</tt> must be smaller than the bit size of the destination type, 
<tt>ty2</tt>.</p>

<h5>Semantics:</h5>
<p>The <tt>zext</tt> fills the high order bits of the <tt>value</tt> with zero
bits until it reaches the size of the destination type, <tt>ty2</tt>.</p>

<p>When zero extending from i1, the result will always be either 0 or 1.</p>

<h5>Example:</h5>
<pre>
  %X = zext i32 257 to i64              <i>; yields i64:257</i>
  %Y = zext i1 true to i32              <i>; yields i32:1</i>
</pre>
</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
   <a name="i_sext">'<tt>sext .. to</tt>' Instruction</a>
</div>
<div class="doc_text">

<h5>Syntax:</h5>
<pre>
  &lt;result&gt; = sext &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt;             <i>; yields ty2</i>
</pre>

<h5>Overview:</h5>
<p>The '<tt>sext</tt>' sign extends <tt>value</tt> to the type <tt>ty2</tt>.</p>

<h5>Arguments:</h5>
<p>
The '<tt>sext</tt>' instruction takes a value to cast, which must be of 
<a href="#t_integer">integer</a> type, and a type to cast it to, which must
also be of <a href="#t_integer">integer</a> type.  The bit size of the
<tt>value</tt> must be smaller than the bit size of the destination type, 
<tt>ty2</tt>.</p>

<h5>Semantics:</h5>
<p>
The '<tt>sext</tt>' instruction performs a sign extension by copying the sign
bit (highest order bit) of the <tt>value</tt> until it reaches the bit size of
the type <tt>ty2</tt>.</p>

<p>When sign extending from i1, the extension always results in -1 or 0.</p>

<h5>Example:</h5>
<pre>
  %X = sext i8  -1 to i16              <i>; yields i16   :65535</i>
  %Y = sext i1 true to i32             <i>; yields i32:-1</i>
</pre>
</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
   <a name="i_fptrunc">'<tt>fptrunc .. to</tt>' Instruction</a>
</div>

<div class="doc_text">

<h5>Syntax:</h5>

<pre>
  &lt;result&gt; = fptrunc &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt;             <i>; yields ty2</i>
</pre>

<h5>Overview:</h5>
<p>The '<tt>fptrunc</tt>' instruction truncates <tt>value</tt> to type
<tt>ty2</tt>.</p>


<h5>Arguments:</h5>
<p>The '<tt>fptrunc</tt>' instruction takes a <a href="#t_floating">floating
  point</a> value to cast and a <a href="#t_floating">floating point</a> type to
cast it to. The size of <tt>value</tt> must be larger than the size of
<tt>ty2</tt>. This implies that <tt>fptrunc</tt> cannot be used to make a 
<i>no-op cast</i>.</p>

<h5>Semantics:</h5>
<p> The '<tt>fptrunc</tt>' instruction truncates a <tt>value</tt> from a larger
<a href="#t_floating">floating point</a> type to a smaller 
<a href="#t_floating">floating point</a> type.  If the value cannot fit within 
the destination type, <tt>ty2</tt>, then the results are undefined.</p>

<h5>Example:</h5>
<pre>
  %X = fptrunc double 123.0 to float         <i>; yields float:123.0</i>
  %Y = fptrunc double 1.0E+300 to float      <i>; yields undefined</i>
</pre>
</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
   <a name="i_fpext">'<tt>fpext .. to</tt>' Instruction</a>
</div>
<div class="doc_text">

<h5>Syntax:</h5>
<pre>
  &lt;result&gt; = fpext &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt;             <i>; yields ty2</i>
</pre>

<h5>Overview:</h5>
<p>The '<tt>fpext</tt>' extends a floating point <tt>value</tt> to a larger
floating point value.</p>

<h5>Arguments:</h5>
<p>The '<tt>fpext</tt>' instruction takes a 
<a href="#t_floating">floating point</a> <tt>value</tt> to cast, 
and a <a href="#t_floating">floating point</a> type to cast it to. The source
type must be smaller than the destination type.</p>

<h5>Semantics:</h5>
<p>The '<tt>fpext</tt>' instruction extends the <tt>value</tt> from a smaller
<a href="#t_floating">floating point</a> type to a larger 
<a href="#t_floating">floating point</a> type. The <tt>fpext</tt> cannot be 
used to make a <i>no-op cast</i> because it always changes bits. Use 
<tt>bitcast</tt> to make a <i>no-op cast</i> for a floating point cast.</p>

<h5>Example:</h5>
<pre>
  %X = fpext float 3.1415 to double        <i>; yields double:3.1415</i>
  %Y = fpext float 1.0 to float            <i>; yields float:1.0 (no-op)</i>
</pre>
</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
   <a name="i_fptoui">'<tt>fptoui .. to</tt>' Instruction</a>
</div>
<div class="doc_text">

<h5>Syntax:</h5>
<pre>
  &lt;result&gt; = fp2uint &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt;             <i>; yields ty2</i>
</pre>

<h5>Overview:</h5>
<p>The '<tt>fp2uint</tt>' converts a floating point <tt>value</tt> to its
unsigned integer equivalent of type <tt>ty2</tt>.
</p>

<h5>Arguments:</h5>
<p>The '<tt>fp2uint</tt>' instruction takes a value to cast, which must be a 
<a href="#t_floating">floating point</a> value, and a type to cast it to, which
must be an <a href="#t_integer">integer</a> type.</p>

<h5>Semantics:</h5>
<p> The '<tt>fp2uint</tt>' instruction converts its 
<a href="#t_floating">floating point</a> operand into the nearest (rounding
towards zero) unsigned integer value. If the value cannot fit in <tt>ty2</tt>,
the results are undefined.</p>

<p>When converting to i1, the conversion is done as a comparison against 
zero. If the <tt>value</tt> was zero, the i1 result will be <tt>false</tt>. 
If the <tt>value</tt> was non-zero, the i1 result will be <tt>true</tt>.</p>

<h5>Example:</h5>
<pre>
  %X = fp2uint double 123.0 to i32      <i>; yields i32:123</i>
  %Y = fp2uint float 1.0E+300 to i1     <i>; yields i1:true</i>
  %X = fp2uint float 1.04E+17 to i8     <i>; yields undefined:1</i>
</pre>
</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
   <a name="i_fptosi">'<tt>fptosi .. to</tt>' Instruction</a>
</div>
<div class="doc_text">

<h5>Syntax:</h5>
<pre>
  &lt;result&gt; = fptosi &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt;             <i>; yields ty2</i>
</pre>

<h5>Overview:</h5>
<p>The '<tt>fptosi</tt>' instruction converts 
<a href="#t_floating">floating point</a> <tt>value</tt> to type <tt>ty2</tt>.
</p>


<h5>Arguments:</h5>
<p> The '<tt>fptosi</tt>' instruction takes a value to cast, which must be a 
<a href="#t_floating">floating point</a> value, and a type to cast it to, which 
must also be an <a href="#t_integer">integer</a> type.</p>

<h5>Semantics:</h5>
<p>The '<tt>fptosi</tt>' instruction converts its 
<a href="#t_floating">floating point</a> operand into the nearest (rounding
towards zero) signed integer value. If the value cannot fit in <tt>ty2</tt>,
the results are undefined.</p>

<p>When converting to i1, the conversion is done as a comparison against 
zero. If the <tt>value</tt> was zero, the i1 result will be <tt>false</tt>. 
If the <tt>value</tt> was non-zero, the i1 result will be <tt>true</tt>.</p>

<h5>Example:</h5>
<pre>
  %X = fptosi double -123.0 to i32      <i>; yields i32:-123</i>
  %Y = fptosi float 1.0E-247 to i1      <i>; yields i1:true</i>
  %X = fptosi float 1.04E+17 to i8      <i>; yields undefined:1</i>
</pre>
</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
   <a name="i_uitofp">'<tt>uitofp .. to</tt>' Instruction</a>
</div>
<div class="doc_text">

<h5>Syntax:</h5>
<pre>
  &lt;result&gt; = uitofp &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt;             <i>; yields ty2</i>
</pre>

<h5>Overview:</h5>
<p>The '<tt>uitofp</tt>' instruction regards <tt>value</tt> as an unsigned
integer and converts that value to the <tt>ty2</tt> type.</p>


<h5>Arguments:</h5>
<p>The '<tt>uitofp</tt>' instruction takes a value to cast, which must be an
<a href="#t_integer">integer</a> value, and a type to cast it to, which must 
be a <a href="#t_floating">floating point</a> type.</p>

<h5>Semantics:</h5>
<p>The '<tt>uitofp</tt>' instruction interprets its operand as an unsigned
integer quantity and converts it to the corresponding floating point value. If
the value cannot fit in the floating point value, the results are undefined.</p>


<h5>Example:</h5>
<pre>
  %X = uitofp i32 257 to float         <i>; yields float:257.0</i>
  %Y = uitofp i8  -1 to double         <i>; yields double:255.0</i>
</pre>
</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
   <a name="i_sitofp">'<tt>sitofp .. to</tt>' Instruction</a>
</div>
<div class="doc_text">

<h5>Syntax:</h5>
<pre>
  &lt;result&gt; = sitofp &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt;             <i>; yields ty2</i>
</pre>

<h5>Overview:</h5>
<p>The '<tt>sitofp</tt>' instruction regards <tt>value</tt> as a signed
integer and converts that value to the <tt>ty2</tt> type.</p>

<h5>Arguments:</h5>
<p>The '<tt>sitofp</tt>' instruction takes a value to cast, which must be an
<a href="#t_integer">integer</a> value, and a type to cast it to, which must be
a <a href="#t_floating">floating point</a> type.</p>

<h5>Semantics:</h5>
<p>The '<tt>sitofp</tt>' instruction interprets its operand as a signed
integer quantity and converts it to the corresponding floating point value. If
the value cannot fit in the floating point value, the results are undefined.</p>

<h5>Example:</h5>
<pre>
  %X = sitofp i32 257 to float         <i>; yields float:257.0</i>
  %Y = sitofp i8  -1 to double         <i>; yields double:-1.0</i>
</pre>
</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
   <a name="i_ptrtoint">'<tt>ptrtoint .. to</tt>' Instruction</a>
</div>
<div class="doc_text">

<h5>Syntax:</h5>
<pre>
  &lt;result&gt; = ptrtoint &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt;             <i>; yields ty2</i>
</pre>

<h5>Overview:</h5>
<p>The '<tt>ptrtoint</tt>' instruction converts the pointer <tt>value</tt> to 
the integer type <tt>ty2</tt>.</p>

<h5>Arguments:</h5>
<p>The '<tt>ptrtoint</tt>' instruction takes a <tt>value</tt> to cast, which 
must be a <a href="#t_pointer">pointer</a> value, and a type to cast it to
<tt>ty2</tt>, which must be an <a href="#t_integer">integer</a> type. 

<h5>Semantics:</h5>
<p>The '<tt>ptrtoint</tt>' instruction converts <tt>value</tt> to integer type
<tt>ty2</tt> by interpreting the pointer value as an integer and either 
truncating or zero extending that value to the size of the integer type. If
<tt>value</tt> is smaller than <tt>ty2</tt> then a zero extension is done. If
<tt>value</tt> is larger than <tt>ty2</tt> then a truncation is done. If they
are the same size, then nothing is done (<i>no-op cast</i>) other than a type
change.</p>

<h5>Example:</h5>
<pre>
  %X = ptrtoint i32* %X to i8           <i>; yields truncation on 32-bit architecture</i>
  %Y = ptrtoint i32* %x to i64          <i>; yields zero extension on 32-bit architecture</i>
</pre>
</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
   <a name="i_inttoptr">'<tt>inttoptr .. to</tt>' Instruction</a>
</div>
<div class="doc_text">

<h5>Syntax:</h5>
<pre>
  &lt;result&gt; = inttoptr &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt;             <i>; yields ty2</i>
</pre>

<h5>Overview:</h5>
<p>The '<tt>inttoptr</tt>' instruction converts an integer <tt>value</tt> to 
a pointer type, <tt>ty2</tt>.</p>

<h5>Arguments:</h5>
<p>The '<tt>inttoptr</tt>' instruction takes an <a href="#t_integer">integer</a>
value to cast, and a type to cast it to, which must be a 
<a href="#t_pointer">pointer</a> type.

<h5>Semantics:</h5>
<p>The '<tt>inttoptr</tt>' instruction converts <tt>value</tt> to type
<tt>ty2</tt> by applying either a zero extension or a truncation depending on
the size of the integer <tt>value</tt>. If <tt>value</tt> is larger than the
size of a pointer then a truncation is done. If <tt>value</tt> is smaller than
the size of a pointer then a zero extension is done. If they are the same size,
nothing is done (<i>no-op cast</i>).</p>

<h5>Example:</h5>
<pre>
  %X = inttoptr i32 255 to i32*          <i>; yields zero extension on 64-bit architecture</i>
  %X = inttoptr i32 255 to i32*          <i>; yields no-op on 32-bit architecture</i>
  %Y = inttoptr i64 0 to i32*            <i>; yields truncation on 32-bit architecture</i>
</pre>
</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
   <a name="i_bitcast">'<tt>bitcast .. to</tt>' Instruction</a>
</div>
<div class="doc_text">

<h5>Syntax:</h5>
<pre>
  &lt;result&gt; = bitcast &lt;ty&gt; &lt;value&gt; to &lt;ty2&gt;             <i>; yields ty2</i>
</pre>

<h5>Overview:</h5>
<p>The '<tt>bitcast</tt>' instruction converts <tt>value</tt> to type
<tt>ty2</tt> without changing any bits.</p>

<h5>Arguments:</h5>
<p>The '<tt>bitcast</tt>' instruction takes a value to cast, which must be 
a first class value, and a type to cast it to, which must also be a <a
  href="#t_firstclass">first class</a> type. The bit sizes of <tt>value</tt>
and the destination type, <tt>ty2</tt>, must be identical. If the source
type is a pointer, the destination type must also be a pointer.</p>

<h5>Semantics:</h5>
<p>The '<tt>bitcast</tt>' instruction converts <tt>value</tt> to type
<tt>ty2</tt>. It is always a <i>no-op cast</i> because no bits change with 
this conversion.  The conversion is done as if the <tt>value</tt> had been 
stored to memory and read back as type <tt>ty2</tt>. Pointer types may only be
converted to other pointer types with this instruction. To convert pointers to 
other types, use the <a href="#i_inttoptr">inttoptr</a> or 
<a href="#i_ptrtoint">ptrtoint</a> instructions first.</p>

<h5>Example:</h5>
<pre>
  %X = bitcast i8 255 to i8              <i>; yields i8 :-1</i>
  %Y = bitcast i32* %x to sint*          <i>; yields sint*:%x</i>
  %Z = bitcast <2xint> %V to i64;        <i>; yields i64: %V</i>   
</pre>
</div>

<!-- ======================================================================= -->
<div class="doc_subsection"> <a name="otherops">Other Operations</a> </div>
<div class="doc_text">
<p>The instructions in this category are the "miscellaneous"
instructions, which defy better classification.</p>
</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection"><a name="i_icmp">'<tt>icmp</tt>' Instruction</a>
</div>
<div class="doc_text">
<h5>Syntax:</h5>
<pre>  &lt;result&gt; = icmp &lt;cond&gt; &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt;   <i>; yields {i1}:result</i>
</pre>
<h5>Overview:</h5>
<p>The '<tt>icmp</tt>' instruction returns a boolean value based on comparison
of its two integer operands.</p>
<h5>Arguments:</h5>
<p>The '<tt>icmp</tt>' instruction takes three operands. The first operand is
the condition code indicating the kind of comparison to perform. It is not
a value, just a keyword. The possible condition code are:
<ol>
  <li><tt>eq</tt>: equal</li>
  <li><tt>ne</tt>: not equal </li>
  <li><tt>ugt</tt>: unsigned greater than</li>
  <li><tt>uge</tt>: unsigned greater or equal</li>
  <li><tt>ult</tt>: unsigned less than</li>
  <li><tt>ule</tt>: unsigned less or equal</li>
  <li><tt>sgt</tt>: signed greater than</li>
  <li><tt>sge</tt>: signed greater or equal</li>
  <li><tt>slt</tt>: signed less than</li>
  <li><tt>sle</tt>: signed less or equal</li>
</ol>
<p>The remaining two arguments must be <a href="#t_integer">integer</a> or
<a href="#t_pointer">pointer</a> typed. They must also be identical types.</p>
<h5>Semantics:</h5>
<p>The '<tt>icmp</tt>' compares <tt>var1</tt> and <tt>var2</tt> according to 
the condition code given as <tt>cond</tt>. The comparison performed always
yields a <a href="#t_primitive">i1</a> result, as follows: 
<ol>
  <li><tt>eq</tt>: yields <tt>true</tt> if the operands are equal, 
  <tt>false</tt> otherwise. No sign interpretation is necessary or performed.
  </li>
  <li><tt>ne</tt>: yields <tt>true</tt> if the operands are unequal, 
  <tt>false</tt> otherwise. No sign interpretation is necessary or performed.
  <li><tt>ugt</tt>: interprets the operands as unsigned values and yields
  <tt>true</tt> if <tt>var1</tt> is greater than <tt>var2</tt>.</li>
  <li><tt>uge</tt>: interprets the operands as unsigned values and yields
  <tt>true</tt> if <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
  <li><tt>ult</tt>: interprets the operands as unsigned values and yields
  <tt>true</tt> if <tt>var1</tt> is less than <tt>var2</tt>.</li>
  <li><tt>ule</tt>: interprets the operands as unsigned values and yields
  <tt>true</tt> if <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
  <li><tt>sgt</tt>: interprets the operands as signed values and yields
  <tt>true</tt> if <tt>var1</tt> is greater than <tt>var2</tt>.</li>
  <li><tt>sge</tt>: interprets the operands as signed values and yields
  <tt>true</tt> if <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
  <li><tt>slt</tt>: interprets the operands as signed values and yields
  <tt>true</tt> if <tt>var1</tt> is less than <tt>var2</tt>.</li>
  <li><tt>sle</tt>: interprets the operands as signed values and yields
  <tt>true</tt> if <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
</ol>
<p>If the operands are <a href="#t_pointer">pointer</a> typed, the pointer
values are compared as if they were integers.</p>

<h5>Example:</h5>
<pre>  &lt;result&gt; = icmp eq i32 4, 5          <i>; yields: result=false</i>
  &lt;result&gt; = icmp ne float* %X, %X     <i>; yields: result=false</i>
  &lt;result&gt; = icmp ult i16  4, 5        <i>; yields: result=true</i>
  &lt;result&gt; = icmp sgt i16  4, 5        <i>; yields: result=false</i>
  &lt;result&gt; = icmp ule i16 -4, 5        <i>; yields: result=false</i>
  &lt;result&gt; = icmp sge i16  4, 5        <i>; yields: result=false</i>
</pre>
</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection"><a name="i_fcmp">'<tt>fcmp</tt>' Instruction</a>
</div>
<div class="doc_text">
<h5>Syntax:</h5>
<pre>  &lt;result&gt; = fcmp &lt;cond&gt; &lt;ty&gt; &lt;var1&gt;, &lt;var2&gt;     <i>; yields {i1}:result</i>
</pre>
<h5>Overview:</h5>
<p>The '<tt>fcmp</tt>' instruction returns a boolean value based on comparison
of its floating point operands.</p>
<h5>Arguments:</h5>
<p>The '<tt>fcmp</tt>' instruction takes three operands. The first operand is
the condition code indicating the kind of comparison to perform. It is not
a value, just a keyword. The possible condition code are:
<ol>
  <li><tt>false</tt>: no comparison, always returns false</li>
  <li><tt>oeq</tt>: ordered and equal</li>
  <li><tt>ogt</tt>: ordered and greater than </li>
  <li><tt>oge</tt>: ordered and greater than or equal</li>
  <li><tt>olt</tt>: ordered and less than </li>
  <li><tt>ole</tt>: ordered and less than or equal</li>
  <li><tt>one</tt>: ordered and not equal</li>
  <li><tt>ord</tt>: ordered (no nans)</li>
  <li><tt>ueq</tt>: unordered or equal</li>
  <li><tt>ugt</tt>: unordered or greater than </li>
  <li><tt>uge</tt>: unordered or greater than or equal</li>
  <li><tt>ult</tt>: unordered or less than </li>
  <li><tt>ule</tt>: unordered or less than or equal</li>
  <li><tt>une</tt>: unordered or not equal</li>
  <li><tt>uno</tt>: unordered (either nans)</li>
  <li><tt>true</tt>: no comparison, always returns true</li>
</ol>
<p><i>Ordered</i> means that neither operand is a QNAN while
<i>unordered</i> means that either operand may be a QNAN.</p>
<p>The <tt>val1</tt> and <tt>val2</tt> arguments must be
<a href="#t_floating">floating point</a> typed.  They must have identical 
types.</p>
<h5>Semantics:</h5>
<p>The '<tt>fcmp</tt>' compares <tt>var1</tt> and <tt>var2</tt> according to 
the condition code given as <tt>cond</tt>. The comparison performed always
yields a <a href="#t_primitive">i1</a> result, as follows: 
<ol>
  <li><tt>false</tt>: always yields <tt>false</tt>, regardless of operands.</li>
  <li><tt>oeq</tt>: yields <tt>true</tt> if both operands are not a QNAN and 
  <tt>var1</tt> is equal to <tt>var2</tt>.</li>
  <li><tt>ogt</tt>: yields <tt>true</tt> if both operands are not a QNAN and
  <tt>var1</tt> is greather than <tt>var2</tt>.</li>
  <li><tt>oge</tt>: yields <tt>true</tt> if both operands are not a QNAN and 
  <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
  <li><tt>olt</tt>: yields <tt>true</tt> if both operands are not a QNAN and 
  <tt>var1</tt> is less than <tt>var2</tt>.</li>
  <li><tt>ole</tt>: yields <tt>true</tt> if both operands are not a QNAN and 
  <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
  <li><tt>one</tt>: yields <tt>true</tt> if both operands are not a QNAN and 
  <tt>var1</tt> is not equal to <tt>var2</tt>.</li>
  <li><tt>ord</tt>: yields <tt>true</tt> if both operands are not a QNAN.</li>
  <li><tt>ueq</tt>: yields <tt>true</tt> if either operand is a QNAN or 
  <tt>var1</tt> is equal to <tt>var2</tt>.</li>
  <li><tt>ugt</tt>: yields <tt>true</tt> if either operand is a QNAN or 
  <tt>var1</tt> is greater than <tt>var2</tt>.</li>
  <li><tt>uge</tt>: yields <tt>true</tt> if either operand is a QNAN or 
  <tt>var1</tt> is greater than or equal to <tt>var2</tt>.</li>
  <li><tt>ult</tt>: yields <tt>true</tt> if either operand is a QNAN or 
  <tt>var1</tt> is less than <tt>var2</tt>.</li>
  <li><tt>ule</tt>: yields <tt>true</tt> if either operand is a QNAN or 
  <tt>var1</tt> is less than or equal to <tt>var2</tt>.</li>
  <li><tt>une</tt>: yields <tt>true</tt> if either operand is a QNAN or 
  <tt>var1</tt> is not equal to <tt>var2</tt>.</li>
  <li><tt>uno</tt>: yields <tt>true</tt> if either operand is a QNAN.</li>
  <li><tt>true</tt>: always yields <tt>true</tt>, regardless of operands.</li>
</ol>

<h5>Example:</h5>
<pre>  &lt;result&gt; = fcmp oeq float 4.0, 5.0    <i>; yields: result=false</i>
  &lt;result&gt; = icmp one float 4.0, 5.0    <i>; yields: result=true</i>
  &lt;result&gt; = icmp olt float 4.0, 5.0    <i>; yields: result=true</i>
  &lt;result&gt; = icmp ueq double 1.0, 2.0   <i>; yields: result=false</i>
</pre>
</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection"> <a name="i_phi">'<tt>phi</tt>'
Instruction</a> </div>
<div class="doc_text">
<h5>Syntax:</h5>
<pre>  &lt;result&gt; = phi &lt;ty&gt; [ &lt;val0&gt;, &lt;label0&gt;], ...<br></pre>
<h5>Overview:</h5>
<p>The '<tt>phi</tt>' instruction is used to implement the &#966; node in
the SSA graph representing the function.</p>
<h5>Arguments:</h5>
<p>The type of the incoming values is specified with the first type
field. After this, the '<tt>phi</tt>' instruction takes a list of pairs
as arguments, with one pair for each predecessor basic block of the
current block.  Only values of <a href="#t_firstclass">first class</a>
type may be used as the value arguments to the PHI node.  Only labels
may be used as the label arguments.</p>
<p>There must be no non-phi instructions between the start of a basic
block and the PHI instructions: i.e. PHI instructions must be first in
a basic block.</p>
<h5>Semantics:</h5>
<p>At runtime, the '<tt>phi</tt>' instruction logically takes on the value
specified by the pair corresponding to the predecessor basic block that executed
just prior to the current block.</p>
<h5>Example:</h5>
<pre>Loop:       ; Infinite loop that counts from 0 on up...<br>  %indvar = phi i32 [ 0, %LoopHeader ], [ %nextindvar, %Loop ]<br>  %nextindvar = add i32 %indvar, 1<br>  br label %Loop<br></pre>
</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
   <a name="i_select">'<tt>select</tt>' Instruction</a>
</div>

<div class="doc_text">

<h5>Syntax:</h5>

<pre>
  &lt;result&gt; = select i1 &lt;cond&gt;, &lt;ty&gt; &lt;val1&gt;, &lt;ty&gt; &lt;val2&gt;             <i>; yields ty</i>
</pre>

<h5>Overview:</h5>

<p>
The '<tt>select</tt>' instruction is used to choose one value based on a
condition, without branching.
</p>


<h5>Arguments:</h5>

<p>
The '<tt>select</tt>' instruction requires a boolean value indicating the condition, and two values of the same <a href="#t_firstclass">first class</a> type.
</p>

<h5>Semantics:</h5>

<p>
If the boolean condition evaluates to true, the instruction returns the first
value argument; otherwise, it returns the second value argument.
</p>

<h5>Example:</h5>

<pre>
  %X = select i1 true, i8 17, i8 42          <i>; yields i8:17</i>
</pre>
</div>


<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
  <a name="i_call">'<tt>call</tt>' Instruction</a>
</div>

<div class="doc_text">

<h5>Syntax:</h5>
<pre>
  &lt;result&gt; = [tail] call [<a href="#callingconv">cconv</a>] &lt;ty&gt;* &lt;fnptrval&gt;(&lt;param list&gt;)
</pre>

<h5>Overview:</h5>

<p>The '<tt>call</tt>' instruction represents a simple function call.</p>

<h5>Arguments:</h5>

<p>This instruction requires several arguments:</p>

<ol>
  <li>
    <p>The optional "tail" marker indicates whether the callee function accesses
    any allocas or varargs in the caller.  If the "tail" marker is present, the
    function call is eligible for tail call optimization.  Note that calls may
    be marked "tail" even if they do not occur before a <a
    href="#i_ret"><tt>ret</tt></a> instruction.
  </li>
  <li>
    <p>The optional "cconv" marker indicates which <a href="#callingconv">calling
    convention</a> the call should use.  If none is specified, the call defaults
    to using C calling conventions.
  </li>
  <li>
    <p>'<tt>ty</tt>': shall be the signature of the pointer to function value
    being invoked.  The argument types must match the types implied by this
    signature.  This type can be omitted if the function is not varargs and
    if the function type does not return a pointer to a function.</p>
  </li>
  <li>
    <p>'<tt>fnptrval</tt>': An LLVM value containing a pointer to a function to
    be invoked. In most cases, this is a direct function invocation, but
    indirect <tt>call</tt>s are just as possible, calling an arbitrary pointer
    to function value.</p>
  </li>
  <li>
    <p>'<tt>function args</tt>': argument list whose types match the
    function signature argument types. All arguments must be of 
    <a href="#t_firstclass">first class</a> type. If the function signature 
    indicates the function accepts a variable number of arguments, the extra 
    arguments can be specified.</p>
  </li>
</ol>

<h5>Semantics:</h5>

<p>The '<tt>call</tt>' instruction is used to cause control flow to
transfer to a specified function, with its incoming arguments bound to
the specified values. Upon a '<tt><a href="#i_ret">ret</a></tt>'
instruction in the called function, control flow continues with the
instruction after the function call, and the return value of the
function is bound to the result argument.  This is a simpler case of
the <a href="#i_invoke">invoke</a> instruction.</p>

<h5>Example:</h5>

<pre>
  %retval = call i32 %test(i32 %argc)
  call i32(i8 *, ...) *%printf(i8 * %msg, i32 12, i8 42);
  %X = tail call i32 %foo()
  %Y = tail call <a href="#callingconv">fastcc</a> i32 %foo()
</pre>

</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
  <a name="i_va_arg">'<tt>va_arg</tt>' Instruction</a>
</div>

<div class="doc_text">

<h5>Syntax:</h5>

<pre>
  &lt;resultval&gt; = va_arg &lt;va_list*&gt; &lt;arglist&gt;, &lt;argty&gt;
</pre>

<h5>Overview:</h5>

<p>The '<tt>va_arg</tt>' instruction is used to access arguments passed through
the "variable argument" area of a function call.  It is used to implement the
<tt>va_arg</tt> macro in C.</p>

<h5>Arguments:</h5>

<p>This instruction takes a <tt>va_list*</tt> value and the type of
the argument. It returns a value of the specified argument type and
increments the <tt>va_list</tt> to point to the next argument.  The
actual type of <tt>va_list</tt> is target specific.</p>

<h5>Semantics:</h5>

<p>The '<tt>va_arg</tt>' instruction loads an argument of the specified
type from the specified <tt>va_list</tt> and causes the
<tt>va_list</tt> to point to the next argument.  For more information,
see the variable argument handling <a href="#int_varargs">Intrinsic
Functions</a>.</p>

<p>It is legal for this instruction to be called in a function which does not
take a variable number of arguments, for example, the <tt>vfprintf</tt>
function.</p>

<p><tt>va_arg</tt> is an LLVM instruction instead of an <a
href="#intrinsics">intrinsic function</a> because it takes a type as an
argument.</p>

<h5>Example:</h5>

<p>See the <a href="#int_varargs">variable argument processing</a> section.</p>

</div>

<!-- *********************************************************************** -->
<div class="doc_section"> <a name="intrinsics">Intrinsic Functions</a> </div>
<!-- *********************************************************************** -->

<div class="doc_text">

<p>LLVM supports the notion of an "intrinsic function".  These functions have
well known names and semantics and are required to follow certain restrictions.
Overall, these intrinsics represent an extension mechanism for the LLVM 
language that does not require changing all of the transformations in LLVM when 
adding to the language (or the bitcode reader/writer, the parser, etc...).</p>

<p>Intrinsic function names must all start with an "<tt>llvm.</tt>" prefix. This
prefix is reserved in LLVM for intrinsic names; thus, function names may not
begin with this prefix.  Intrinsic functions must always be external functions:
you cannot define the body of intrinsic functions.  Intrinsic functions may
only be used in call or invoke instructions: it is illegal to take the address
of an intrinsic function.  Additionally, because intrinsic functions are part
of the LLVM language, it is required if any are added that they be documented
here.</p>

<p>Some intrinsic functions can be overloaded, i.e., the intrinsic represents
a family of functions that perform the same operation but on different data
types. This is most frequent with the integer types. Since LLVM can represent
over 8 million different integer types, there is a way to declare an intrinsic 
that can be overloaded based on its arguments. Such an intrinsic will have the
names of its argument types encoded into its function name, each
preceded by a period. For example, the <tt>llvm.ctpop</tt> function can take an
integer of any width. This leads to a family of functions such as 
<tt>i32 @llvm.ctpop.i8(i8 %val)</tt> and <tt>i32 @llvm.ctpop.i29(i29 %val)</tt>.
</p>


<p>To learn how to add an intrinsic function, please see the 
<a href="ExtendingLLVM.html">Extending LLVM Guide</a>.
</p>

</div>

<!-- ======================================================================= -->
<div class="doc_subsection">
  <a name="int_varargs">Variable Argument Handling Intrinsics</a>
</div>

<div class="doc_text">

<p>Variable argument support is defined in LLVM with the <a
 href="#i_va_arg"><tt>va_arg</tt></a> instruction and these three
intrinsic functions.  These functions are related to the similarly
named macros defined in the <tt>&lt;stdarg.h&gt;</tt> header file.</p>

<p>All of these functions operate on arguments that use a
target-specific value type "<tt>va_list</tt>".  The LLVM assembly
language reference manual does not define what this type is, so all
transformations should be prepared to handle these functions regardless of
the type used.</p>

<p>This example shows how the <a href="#i_va_arg"><tt>va_arg</tt></a>
instruction and the variable argument handling intrinsic functions are
used.</p>

<div class="doc_code">
<pre>
define i32 @test(i32 %X, ...) {
  ; Initialize variable argument processing
  %ap = alloca i8*
  %ap2 = bitcast i8** %ap to i8*
  call void @llvm.va_start(i8* %ap2)

  ; Read a single integer argument
  %tmp = va_arg i8** %ap, i32

  ; Demonstrate usage of llvm.va_copy and llvm.va_end
  %aq = alloca i8*
  %aq2 = bitcast i8** %aq to i8*
  call void @llvm.va_copy(i8* %aq2, i8* %ap2)
  call void @llvm.va_end(i8* %aq2)

  ; Stop processing of arguments.
  call void @llvm.va_end(i8* %ap2)
  ret i32 %tmp
}

declare void @llvm.va_start(i8*)
declare void @llvm.va_copy(i8*, i8*)
declare void @llvm.va_end(i8*)
</pre>
</div>

</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
  <a name="int_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a>
</div>


<div class="doc_text">
<h5>Syntax:</h5>
<pre>  declare void %llvm.va_start(i8* &lt;arglist&gt;)<br></pre>
<h5>Overview:</h5>
<P>The '<tt>llvm.va_start</tt>' intrinsic initializes
<tt>*&lt;arglist&gt;</tt> for subsequent use by <tt><a
href="#i_va_arg">va_arg</a></tt>.</p>

<h5>Arguments:</h5>

<P>The argument is a pointer to a <tt>va_list</tt> element to initialize.</p>

<h5>Semantics:</h5>

<P>The '<tt>llvm.va_start</tt>' intrinsic works just like the <tt>va_start</tt>
macro available in C.  In a target-dependent way, it initializes the
<tt>va_list</tt> element to which the argument points, so that the next call to
<tt>va_arg</tt> will produce the first variable argument passed to the function.
Unlike the C <tt>va_start</tt> macro, this intrinsic does not need to know the
last argument of the function as the compiler can figure that out.</p>

</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
 <a name="int_va_end">'<tt>llvm.va_end</tt>' Intrinsic</a>
</div>

<div class="doc_text">
<h5>Syntax:</h5>
<pre>  declare void @llvm.va_end(i8* &lt;arglist&gt;)<br></pre>
<h5>Overview:</h5>

<p>The '<tt>llvm.va_end</tt>' intrinsic destroys <tt>*&lt;arglist&gt;</tt>,
which has been initialized previously with <tt><a href="#int_va_start">llvm.va_start</a></tt>
or <tt><a href="#i_va_copy">llvm.va_copy</a></tt>.</p>

<h5>Arguments:</h5>

<p>The argument is a pointer to a <tt>va_list</tt> to destroy.</p>

<h5>Semantics:</h5>

<p>The '<tt>llvm.va_end</tt>' intrinsic works just like the <tt>va_end</tt>
macro available in C.  In a target-dependent way, it destroys the
<tt>va_list</tt> element to which the argument points.  Calls to <a
href="#int_va_start"><tt>llvm.va_start</tt></a> and <a href="#int_va_copy">
<tt>llvm.va_copy</tt></a> must be matched exactly with calls to
<tt>llvm.va_end</tt>.</p>

</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
  <a name="int_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a>
</div>

<div class="doc_text">

<h5>Syntax:</h5>

<pre>
  declare void @llvm.va_copy(i8* &lt;destarglist&gt;, i8* &lt;srcarglist&gt;)
</pre>

<h5>Overview:</h5>

<p>The '<tt>llvm.va_copy</tt>' intrinsic copies the current argument position
from the source argument list to the destination argument list.</p>

<h5>Arguments:</h5>

<p>The first argument is a pointer to a <tt>va_list</tt> element to initialize.
The second argument is a pointer to a <tt>va_list</tt> element to copy from.</p>


<h5>Semantics:</h5>

<p>The '<tt>llvm.va_copy</tt>' intrinsic works just like the <tt>va_copy</tt>
macro available in C.  In a target-dependent way, it copies the source
<tt>va_list</tt> element into the destination <tt>va_list</tt> element.  This
intrinsic is necessary because the <tt><a href="#int_va_start">
llvm.va_start</a></tt> intrinsic may be arbitrarily complex and require, for
example, memory allocation.</p>

</div>

<!-- ======================================================================= -->
<div class="doc_subsection">
  <a name="int_gc">Accurate Garbage Collection Intrinsics</a>
</div>

<div class="doc_text">

<p>
LLVM support for <a href="GarbageCollection.html">Accurate Garbage
Collection</a> requires the implementation and generation of these intrinsics.
These intrinsics allow identification of <a href="#int_gcroot">GC roots on the
stack</a>, as well as garbage collector implementations that require <a
href="#int_gcread">read</a> and <a href="#int_gcwrite">write</a> barriers.
Front-ends for type-safe garbage collected languages should generate these
intrinsics to make use of the LLVM garbage collectors.  For more details, see <a
href="GarbageCollection.html">Accurate Garbage Collection with LLVM</a>.
</p>
</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
  <a name="int_gcroot">'<tt>llvm.gcroot</tt>' Intrinsic</a>
</div>

<div class="doc_text">

<h5>Syntax:</h5>

<pre>
  declare void @llvm.gcroot(&lt;ty&gt;** %ptrloc, &lt;ty2&gt;* %metadata)
</pre>

<h5>Overview:</h5>

<p>The '<tt>llvm.gcroot</tt>' intrinsic declares the existence of a GC root to
the code generator, and allows some metadata to be associated with it.</p>

<h5>Arguments:</h5>

<p>The first argument specifies the address of a stack object that contains the
root pointer.  The second pointer (which must be either a constant or a global
value address) contains the meta-data to be associated with the root.</p>

<h5>Semantics:</h5>

<p>At runtime, a call to this intrinsics stores a null pointer into the "ptrloc"
location.  At compile-time, the code generator generates information to allow
the runtime to find the pointer at GC safe points.
</p>

</div>


<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
  <a name="int_gcread">'<tt>llvm.gcread</tt>' Intrinsic</a>
</div>

<div class="doc_text">

<h5>Syntax:</h5>

<pre>
  declare i8 * @llvm.gcread(i8 * %ObjPtr, i8 ** %Ptr)
</pre>

<h5>Overview:</h5>

<p>The '<tt>llvm.gcread</tt>' intrinsic identifies reads of references from heap
locations, allowing garbage collector implementations that require read
barriers.</p>

<h5>Arguments:</h5>

<p>The second argument is the address to read from, which should be an address
allocated from the garbage collector.  The first object is a pointer to the 
start of the referenced object, if needed by the language runtime (otherwise
null).</p>

<h5>Semantics:</h5>

<p>The '<tt>llvm.gcread</tt>' intrinsic has the same semantics as a load
instruction, but may be replaced with substantially more complex code by the
garbage collector runtime, as needed.</p>

</div>


<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
  <a name="int_gcwrite">'<tt>llvm.gcwrite</tt>' Intrinsic</a>
</div>

<div class="doc_text">

<h5>Syntax:</h5>

<pre>
  declare void @llvm.gcwrite(i8 * %P1, i8 * %Obj, i8 ** %P2)
</pre>

<h5>Overview:</h5>

<p>The '<tt>llvm.gcwrite</tt>' intrinsic identifies writes of references to heap
locations, allowing garbage collector implementations that require write
barriers (such as generational or reference counting collectors).</p>

<h5>Arguments:</h5>

<p>The first argument is the reference to store, the second is the start of the
object to store it to, and the third is the address of the field of Obj to 
store to.  If the runtime does not require a pointer to the object, Obj may be
null.</p>

<h5>Semantics:</h5>

<p>The '<tt>llvm.gcwrite</tt>' intrinsic has the same semantics as a store
instruction, but may be replaced with substantially more complex code by the
garbage collector runtime, as needed.</p>

</div>



<!-- ======================================================================= -->
<div class="doc_subsection">
  <a name="int_codegen">Code Generator Intrinsics</a>
</div>

<div class="doc_text">
<p>
These intrinsics are provided by LLVM to expose special features that may only
be implemented with code generator support.
</p>

</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
  <a name="int_returnaddress">'<tt>llvm.returnaddress</tt>' Intrinsic</a>
</div>

<div class="doc_text">

<h5>Syntax:</h5>
<pre>
  declare i8  *@llvm.returnaddress(i32 &lt;level&gt;)
</pre>

<h5>Overview:</h5>

<p>
The '<tt>llvm.returnaddress</tt>' intrinsic attempts to compute a 
target-specific value indicating the return address of the current function 
or one of its callers.
</p>

<h5>Arguments:</h5>

<p>
The argument to this intrinsic indicates which function to return the address
for.  Zero indicates the calling function, one indicates its caller, etc.  The
argument is <b>required</b> to be a constant integer value.
</p>

<h5>Semantics:</h5>

<p>
The '<tt>llvm.returnaddress</tt>' intrinsic either returns a pointer indicating
the return address of the specified call frame, or zero if it cannot be
identified.  The value returned by this intrinsic is likely to be incorrect or 0
for arguments other than zero, so it should only be used for debugging purposes.
</p>

<p>
Note that calling this intrinsic does not prevent function inlining or other
aggressive transformations, so the value returned may not be that of the obvious
source-language caller.
</p>
</div>


<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
  <a name="int_frameaddress">'<tt>llvm.frameaddress</tt>' Intrinsic</a>
</div>

<div class="doc_text">

<h5>Syntax:</h5>
<pre>
  declare i8  *@llvm.frameaddress(i32 &lt;level&gt;)
</pre>

<h5>Overview:</h5>

<p>
The '<tt>llvm.frameaddress</tt>' intrinsic attempts to return the 
target-specific frame pointer value for the specified stack frame.
</p>

<h5>Arguments:</h5>

<p>
The argument to this intrinsic indicates which function to return the frame
pointer for.  Zero indicates the calling function, one indicates its caller,
etc.  The argument is <b>required</b> to be a constant integer value.
</p>

<h5>Semantics:</h5>

<p>
The '<tt>llvm.frameaddress</tt>' intrinsic either returns a pointer indicating
the frame address of the specified call frame, or zero if it cannot be
identified.  The value returned by this intrinsic is likely to be incorrect or 0
for arguments other than zero, so it should only be used for debugging purposes.
</p>

<p>
Note that calling this intrinsic does not prevent function inlining or other
aggressive transformations, so the value returned may not be that of the obvious
source-language caller.
</p>
</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
  <a name="int_stacksave">'<tt>llvm.stacksave</tt>' Intrinsic</a>
</div>

<div class="doc_text">

<h5>Syntax:</h5>
<pre>
  declare i8  *@llvm.stacksave()
</pre>

<h5>Overview:</h5>

<p>
The '<tt>llvm.stacksave</tt>' intrinsic is used to remember the current state of
the function stack, for use with <a href="#int_stackrestore">
<tt>llvm.stackrestore</tt></a>.  This is useful for implementing language
features like scoped automatic variable sized arrays in C99.
</p>

<h5>Semantics:</h5>

<p>
This intrinsic returns a opaque pointer value that can be passed to <a
href="#int_stackrestore"><tt>llvm.stackrestore</tt></a>.  When an
<tt>llvm.stackrestore</tt> intrinsic is executed with a value saved from 
<tt>llvm.stacksave</tt>, it effectively restores the state of the stack to the
state it was in when the <tt>llvm.stacksave</tt> intrinsic executed.  In
practice, this pops any <a href="#i_alloca">alloca</a> blocks from the stack
that were allocated after the <tt>llvm.stacksave</tt> was executed.
</p>

</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
  <a name="int_stackrestore">'<tt>llvm.stackrestore</tt>' Intrinsic</a>
</div>

<div class="doc_text">

<h5>Syntax:</h5>
<pre>
  declare void @llvm.stackrestore(i8 * %ptr)
</pre>

<h5>Overview:</h5>

<p>
The '<tt>llvm.stackrestore</tt>' intrinsic is used to restore the state of
the function stack to the state it was in when the corresponding <a
href="#int_stacksave"><tt>llvm.stacksave</tt></a> intrinsic executed.  This is
useful for implementing language features like scoped automatic variable sized
arrays in C99.
</p>

<h5>Semantics:</h5>

<p>
See the description for <a href="#int_stacksave"><tt>llvm.stacksave</tt></a>.
</p>

</div>


<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
  <a name="int_prefetch">'<tt>llvm.prefetch</tt>' Intrinsic</a>
</div>

<div class="doc_text">

<h5>Syntax:</h5>
<pre>
  declare void @llvm.prefetch(i8  * &lt;address&gt;,
                                i32 &lt;rw&gt;, i32 &lt;locality&gt;)
</pre>

<h5>Overview:</h5>


<p>
The '<tt>llvm.prefetch</tt>' intrinsic is a hint to the code generator to insert
a prefetch instruction if supported; otherwise, it is a noop.  Prefetches have
no
effect on the behavior of the program but can change its performance
characteristics.
</p>

<h5>Arguments:</h5>

<p>
<tt>address</tt> is the address to be prefetched, <tt>rw</tt> is the specifier
determining if the fetch should be for a read (0) or write (1), and
<tt>locality</tt> is a temporal locality specifier ranging from (0) - no
locality, to (3) - extremely local keep in cache.  The <tt>rw</tt> and
<tt>locality</tt> arguments must be constant integers.
</p>

<h5>Semantics:</h5>

<p>
This intrinsic does not modify the behavior of the program.  In particular,
prefetches cannot trap and do not produce a value.  On targets that support this
intrinsic, the prefetch can provide hints to the processor cache for better
performance.
</p>

</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
  <a name="int_pcmarker">'<tt>llvm.pcmarker</tt>' Intrinsic</a>
</div>

<div class="doc_text">

<h5>Syntax:</h5>
<pre>
  declare void @llvm.pcmarker( i32 &lt;id&gt; )
</pre>

<h5>Overview:</h5>


<p>
The '<tt>llvm.pcmarker</tt>' intrinsic is a method to export a Program Counter
(PC) in a region of 
code to simulators and other tools.  The method is target specific, but it is 
expected that the marker will use exported symbols to transmit the PC of the marker.
The marker makes no guarantees that it will remain with any specific instruction 
after optimizations.  It is possible that the presence of a marker will inhibit 
optimizations.  The intended use is to be inserted after optimizations to allow
correlations of simulation runs.
</p>

<h5>Arguments:</h5>

<p>
<tt>id</tt> is a numerical id identifying the marker.
</p>

<h5>Semantics:</h5>

<p>
This intrinsic does not modify the behavior of the program.  Backends that do not 
support this intrinisic may ignore it.
</p>

</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
  <a name="int_readcyclecounter">'<tt>llvm.readcyclecounter</tt>' Intrinsic</a>
</div>

<div class="doc_text">

<h5>Syntax:</h5>
<pre>
  declare i64 @llvm.readcyclecounter( )
</pre>

<h5>Overview:</h5>


<p>
The '<tt>llvm.readcyclecounter</tt>' intrinsic provides access to the cycle 
counter register (or similar low latency, high accuracy clocks) on those targets
that support it.  On X86, it should map to RDTSC.  On Alpha, it should map to RPCC.
As the backing counters overflow quickly (on the order of 9 seconds on alpha), this
should only be used for small timings.  
</p>

<h5>Semantics:</h5>

<p>
When directly supported, reading the cycle counter should not modify any memory.  
Implementations are allowed to either return a application specific value or a
system wide value.  On backends without support, this is lowered to a constant 0.
</p>

</div>

<!-- ======================================================================= -->
<div class="doc_subsection">
  <a name="int_libc">Standard C Library Intrinsics</a>
</div>

<div class="doc_text">
<p>
LLVM provides intrinsics for a few important standard C library functions.
These intrinsics allow source-language front-ends to pass information about the
alignment of the pointer arguments to the code generator, providing opportunity
for more efficient code generation.
</p>

</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
  <a name="int_memcpy">'<tt>llvm.memcpy</tt>' Intrinsic</a>
</div>

<div class="doc_text">

<h5>Syntax:</h5>
<pre>
  declare void @llvm.memcpy.i32(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
                                i32 &lt;len&gt;, i32 &lt;align&gt;)
  declare void @llvm.memcpy.i64(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
                                i64 &lt;len&gt;, i32 &lt;align&gt;)
</pre>

<h5>Overview:</h5>

<p>
The '<tt>llvm.memcpy.*</tt>' intrinsics copy a block of memory from the source
location to the destination location.
</p>

<p>
Note that, unlike the standard libc function, the <tt>llvm.memcpy.*</tt> 
intrinsics do not return a value, and takes an extra alignment argument.
</p>

<h5>Arguments:</h5>

<p>
The first argument is a pointer to the destination, the second is a pointer to
the source.  The third argument is an integer argument
specifying the number of bytes to copy, and the fourth argument is the alignment
of the source and destination locations.
</p>

<p>
If the call to this intrinisic has an alignment value that is not 0 or 1, then
the caller guarantees that both the source and destination pointers are aligned
to that boundary.
</p>

<h5>Semantics:</h5>

<p>
The '<tt>llvm.memcpy.*</tt>' intrinsics copy a block of memory from the source
location to the destination location, which are not allowed to overlap.  It
copies "len" bytes of memory over.  If the argument is known to be aligned to
some boundary, this can be specified as the fourth argument, otherwise it should
be set to 0 or 1.
</p>
</div>


<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
  <a name="int_memmove">'<tt>llvm.memmove</tt>' Intrinsic</a>
</div>

<div class="doc_text">

<h5>Syntax:</h5>
<pre>
  declare void @llvm.memmove.i32(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
                                 i32 &lt;len&gt;, i32 &lt;align&gt;)
  declare void @llvm.memmove.i64(i8 * &lt;dest&gt;, i8 * &lt;src&gt;,
                                 i64 &lt;len&gt;, i32 &lt;align&gt;)
</pre>

<h5>Overview:</h5>

<p>
The '<tt>llvm.memmove.*</tt>' intrinsics move a block of memory from the source
location to the destination location. It is similar to the
'<tt>llvm.memcmp</tt>' intrinsic but allows the two memory locations to overlap.
</p>

<p>
Note that, unlike the standard libc function, the <tt>llvm.memmove.*</tt> 
intrinsics do not return a value, and takes an extra alignment argument.
</p>

<h5>Arguments:</h5>

<p>
The first argument is a pointer to the destination, the second is a pointer to
the source.  The third argument is an integer argument
specifying the number of bytes to copy, and the fourth argument is the alignment
of the source and destination locations.
</p>

<p>
If the call to this intrinisic has an alignment value that is not 0 or 1, then
the caller guarantees that the source and destination pointers are aligned to
that boundary.
</p>

<h5>Semantics:</h5>

<p>
The '<tt>llvm.memmove.*</tt>' intrinsics copy a block of memory from the source
location to the destination location, which may overlap.  It
copies "len" bytes of memory over.  If the argument is known to be aligned to
some boundary, this can be specified as the fourth argument, otherwise it should
be set to 0 or 1.
</p>
</div>


<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
  <a name="int_memset">'<tt>llvm.memset.*</tt>' Intrinsics</a>
</div>

<div class="doc_text">

<h5>Syntax:</h5>
<pre>
  declare void @llvm.memset.i32(i8 * &lt;dest&gt;, i8 &lt;val&gt;,
                                i32 &lt;len&gt;, i32 &lt;align&gt;)
  declare void @llvm.memset.i64(i8 * &lt;dest&gt;, i8 &lt;val&gt;,
                                i64 &lt;len&gt;, i32 &lt;align&gt;)
</pre>

<h5>Overview:</h5>

<p>
The '<tt>llvm.memset.*</tt>' intrinsics fill a block of memory with a particular
byte value.
</p>

<p>
Note that, unlike the standard libc function, the <tt>llvm.memset</tt> intrinsic
does not return a value, and takes an extra alignment argument.
</p>

<h5>Arguments:</h5>

<p>
The first argument is a pointer to the destination to fill, the second is the
byte value to fill it with, the third argument is an integer
argument specifying the number of bytes to fill, and the fourth argument is the
known alignment of destination location.
</p>

<p>
If the call to this intrinisic has an alignment value that is not 0 or 1, then
the caller guarantees that the destination pointer is aligned to that boundary.
</p>

<h5>Semantics:</h5>

<p>
The '<tt>llvm.memset.*</tt>' intrinsics fill "len" bytes of memory starting at
the
destination location.  If the argument is known to be aligned to some boundary,
this can be specified as the fourth argument, otherwise it should be set to 0 or
1.
</p>
</div>


<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
  <a name="int_sqrt">'<tt>llvm.sqrt.*</tt>' Intrinsic</a>
</div>

<div class="doc_text">

<h5>Syntax:</h5>
<pre>
  declare float @llvm.sqrt.f32(float %Val)
  declare double @llvm.sqrt.f64(double %Val)
</pre>

<h5>Overview:</h5>

<p>
The '<tt>llvm.sqrt</tt>' intrinsics return the sqrt of the specified operand,
returning the same value as the libm '<tt>sqrt</tt>' function would.  Unlike
<tt>sqrt</tt> in libm, however, <tt>llvm.sqrt</tt> has undefined behavior for
negative numbers (which allows for better optimization).
</p>

<h5>Arguments:</h5>

<p>
The argument and return value are floating point numbers of the same type.
</p>

<h5>Semantics:</h5>

<p>
This function returns the sqrt of the specified operand if it is a nonnegative
floating point number.
</p>
</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
  <a name="int_powi">'<tt>llvm.powi.*</tt>' Intrinsic</a>
</div>

<div class="doc_text">

<h5>Syntax:</h5>
<pre>
  declare float  @llvm.powi.f32(float  %Val, i32 %power)
  declare double @llvm.powi.f64(double %Val, i32 %power)
</pre>

<h5>Overview:</h5>

<p>
The '<tt>llvm.powi.*</tt>' intrinsics return the first operand raised to the
specified (positive or negative) power.  The order of evaluation of
multiplications is not defined.
</p>

<h5>Arguments:</h5>

<p>
The second argument is an integer power, and the first is a value to raise to
that power.
</p>

<h5>Semantics:</h5>

<p>
This function returns the first value raised to the second power with an
unspecified sequence of rounding operations.</p>
</div>


<!-- ======================================================================= -->
<div class="doc_subsection">
  <a name="int_manip">Bit Manipulation Intrinsics</a>
</div>

<div class="doc_text">
<p>
LLVM provides intrinsics for a few important bit manipulation operations.
These allow efficient code generation for some algorithms.
</p>

</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
  <a name="int_bswap">'<tt>llvm.bswap.*</tt>' Intrinsics</a>
</div>

<div class="doc_text">

<h5>Syntax:</h5>
<p>This is an overloaded intrinsic function. You can use bswap on any integer
type that is an even number of bytes (i.e. BitWidth % 16 == 0). Note the suffix
that includes the type for the result and the operand.
<pre>
  declare i16 @llvm.bswap.i16.i16(i16 &lt;id&gt;)
  declare i32 @llvm.bswap.i32.i32(i32 &lt;id&gt;)
  declare i64 @llvm.bswap.i64.i64(i64 &lt;id&gt;)
</pre>

<h5>Overview:</h5>

<p>
The '<tt>llvm.bswap</tt>' family of intrinsics is used to byte swap integer 
values with an even number of bytes (positive multiple of 16 bits).  These are 
useful for performing operations on data that is not in the target's native 
byte order.
</p>

<h5>Semantics:</h5>

<p>
The <tt>llvm.bswap.16.i16</tt> intrinsic returns an i16 value that has the high 
and low byte of the input i16 swapped.  Similarly, the <tt>llvm.bswap.i32</tt> 
intrinsic returns an i32 value that has the four bytes of the input i32 
swapped, so that if the input bytes are numbered 0, 1, 2, 3 then the returned 
i32 will have its bytes in 3, 2, 1, 0 order.  The <tt>llvm.bswap.i48.i48</tt>, 
<tt>llvm.bswap.i64.i64</tt> and other intrinsics extend this concept to
additional even-byte lengths (6 bytes, 8 bytes and more, respectively).
</p>

</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
  <a name="int_ctpop">'<tt>llvm.ctpop.*</tt>' Intrinsic</a>
</div>

<div class="doc_text">

<h5>Syntax:</h5>
<p>This is an overloaded intrinsic. You can use llvm.ctpop on any integer bit
width. Not all targets support all bit widths however.
<pre>
  declare i32 @llvm.ctpop.i8 (i8  &lt;src&gt;)
  declare i32 @llvm.ctpop.i16(i16 &lt;src&gt;)
  declare i32 @llvm.ctpop.i32(i32 &lt;src&gt;)
  declare i32 @llvm.ctpop.i64(i64 &lt;src&gt;)
  declare i32 @llvm.ctpop.i256(i256 &lt;src&gt;)
</pre>

<h5>Overview:</h5>

<p>
The '<tt>llvm.ctpop</tt>' family of intrinsics counts the number of bits set in a 
value.
</p>

<h5>Arguments:</h5>

<p>
The only argument is the value to be counted.  The argument may be of any
integer type.  The return type must match the argument type.
</p>

<h5>Semantics:</h5>

<p>
The '<tt>llvm.ctpop</tt>' intrinsic counts the 1's in a variable.
</p>
</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
  <a name="int_ctlz">'<tt>llvm.ctlz.*</tt>' Intrinsic</a>
</div>

<div class="doc_text">

<h5>Syntax:</h5>
<p>This is an overloaded intrinsic. You can use <tt>llvm.ctlz</tt> on any 
integer bit width. Not all targets support all bit widths however.
<pre>
  declare i32 @llvm.ctlz.i8 (i8  &lt;src&gt;)
  declare i32 @llvm.ctlz.i16(i16 &lt;src&gt;)
  declare i32 @llvm.ctlz.i32(i32 &lt;src&gt;)
  declare i32 @llvm.ctlz.i64(i64 &lt;src&gt;)
  declare i32 @llvm.ctlz.i256(i256 &lt;src&gt;)
</pre>

<h5>Overview:</h5>

<p>
The '<tt>llvm.ctlz</tt>' family of intrinsic functions counts the number of 
leading zeros in a variable.
</p>

<h5>Arguments:</h5>

<p>
The only argument is the value to be counted.  The argument may be of any
integer type. The return type must match the argument type.
</p>

<h5>Semantics:</h5>

<p>
The '<tt>llvm.ctlz</tt>' intrinsic counts the leading (most significant) zeros
in a variable.  If the src == 0 then the result is the size in bits of the type
of src. For example, <tt>llvm.ctlz(i32 2) = 30</tt>.
</p>
</div>



<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
  <a name="int_cttz">'<tt>llvm.cttz.*</tt>' Intrinsic</a>
</div>

<div class="doc_text">

<h5>Syntax:</h5>
<p>This is an overloaded intrinsic. You can use <tt>llvm.cttz</tt> on any 
integer bit width. Not all targets support all bit widths however.
<pre>
  declare i32 @llvm.cttz.i8 (i8  &lt;src&gt;)
  declare i32 @llvm.cttz.i16(i16 &lt;src&gt;)
  declare i32 @llvm.cttz.i32(i32 &lt;src&gt;)
  declare i32 @llvm.cttz.i64(i64 &lt;src&gt;)
  declare i32 @llvm.cttz.i256(i256 &lt;src&gt;)
</pre>

<h5>Overview:</h5>

<p>
The '<tt>llvm.cttz</tt>' family of intrinsic functions counts the number of 
trailing zeros.
</p>

<h5>Arguments:</h5>

<p>
The only argument is the value to be counted.  The argument may be of any
integer type.  The return type must match the argument type.
</p>

<h5>Semantics:</h5>

<p>
The '<tt>llvm.cttz</tt>' intrinsic counts the trailing (least significant) zeros
in a variable.  If the src == 0 then the result is the size in bits of the type
of src.  For example, <tt>llvm.cttz(2) = 1</tt>.
</p>
</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
  <a name="int_part_select">'<tt>llvm.part.select.*</tt>' Intrinsic</a>
</div>

<div class="doc_text">

<h5>Syntax:</h5>
<p>This is an overloaded intrinsic. You can use <tt>llvm.part.select</tt> 
on any integer bit width.
<pre>
  declare i17 @llvm.part.select.i17.i17 (i17 %val, i32 %loBit, i32 %hiBit)
  declare i29 @llvm.part.select.i29.i29 (i29 %val, i32 %loBit, i32 %hiBit)
</pre>

<h5>Overview:</h5>
<p>The '<tt>llvm.part.select</tt>' family of intrinsic functions selects a
range of bits from an integer value and returns them in the same bit width as
the original value.</p>

<h5>Arguments:</h5>
<p>The first argument, <tt>%val</tt> and the result may be integer types of 
any bit width but they must have the same bit width. The second and third 
arguments must be <tt>i32</tt> type since they specify only a bit index.</p>

<h5>Semantics:</h5>
<p>The operation of the '<tt>llvm.part.select</tt>' intrinsic has two modes
of operation: forwards and reverse. If <tt>%loBit</tt> is greater than
<tt>%hiBits</tt> then the intrinsic operates in reverse mode. Otherwise it
operates in forward mode.</p>
<p>In forward mode, this intrinsic is the equivalent of shifting <tt>%val</tt>
right by <tt>%loBit</tt> bits and then ANDing it with a mask with
only the <tt>%hiBit - %loBit</tt> bits set, as follows:</p>
<ol>
  <li>The <tt>%val</tt> is shifted right (LSHR) by the number of bits specified
  by <tt>%loBits</tt>. This normalizes the value to the low order bits.</li>
  <li>The <tt>%loBits</tt> value is subtracted from the <tt>%hiBits</tt> value
  to determine the number of bits to retain.</li>
  <li>A mask of the retained bits is created by shifting a -1 value.</li>
  <li>The mask is ANDed with <tt>%val</tt> to produce the result.
</ol>
<p>In reverse mode, a similar computation is made except that the bits are
returned in the reverse order. So, for example, if <tt>X</tt> has the value
<tt>i16 0x0ACF (101011001111)</tt> and we apply 
<tt>part.select(i16 X, 8, 3)</tt> to it, we get back the value 
<tt>i16 0x0026 (000000100110)</tt>.</p>
</div>

<div class="doc_subsubsection">
  <a name="int_part_set">'<tt>llvm.part.set.*</tt>' Intrinsic</a>
</div>

<div class="doc_text">

<h5>Syntax:</h5>
<p>This is an overloaded intrinsic. You can use <tt>llvm.part.set</tt> 
on any integer bit width.
<pre>
  declare i17 @llvm.part.set.i17.i17.i9 (i17 %val, i9 %repl, i32 %lo, i32 %hi)
  declare i29 @llvm.part.set.i29.i29.i9 (i29 %val, i9 %repl, i32 %lo, i32 %hi)
</pre>

<h5>Overview:</h5>
<p>The '<tt>llvm.part.set</tt>' family of intrinsic functions replaces a range
of bits in an integer value with another integer value. It returns the integer
with the replaced bits.</p>

<h5>Arguments:</h5>
<p>The first argument, <tt>%val</tt> and the result may be integer types of 
any bit width but they must have the same bit width. <tt>%val</tt> is the value
whose bits will be replaced.  The second argument, <tt>%repl</tt> may be an
integer of any bit width. The third and fourth arguments must be <tt>i32</tt> 
type since they specify only a bit index.</p>

<h5>Semantics:</h5>
<p>The operation of the '<tt>llvm.part.set</tt>' intrinsic has two modes
of operation: forwards and reverse. If <tt>%lo</tt> is greater than
<tt>%hi</tt> then the intrinsic operates in reverse mode. Otherwise it
operates in forward mode.</p>
<p>For both modes, the <tt>%repl</tt> value is prepared for use by either
truncating it down to the size of the replacement area or zero extending it 
up to that size.</p>
<p>In forward mode, the bits between <tt>%lo</tt> and <tt>%hi</tt> (inclusive)
are replaced with corresponding bits from <tt>%repl</tt>. That is the 0th bit
in <tt>%repl</tt> replaces the <tt>%lo</tt>th bit in <tt>%val</tt> and etc. up
to the <tt>%hi</tt>th bit. 
<p>In reverse mode, a similar computation is made except that the bits are
reversed.  That is, the <tt>0</tt>th bit in <tt>%repl</tt> replaces the 
<tt>%hi</tt> bit in <tt>%val</tt> and etc. down to the <tt>%lo</tt>th bit.
<h5>Examples:</h5>
<pre>
  llvm.part.set(0xFFFF, 0, 4, 7) -&gt; 0xFF0F
  llvm.part.set(0xFFFF, 0, 7, 4) -&gt; 0xFF0F
  llvm.part.set(0xFFFF, 1, 7, 4) -&gt; 0xFF8F
  llvm.part.set(0xFFFF, F, 8, 3) -&gt; 0xFFE7
  llvm.part.set(0xFFFF, 0, 3, 8) -&gt; 0xFE07
</pre>
</div>

<!-- ======================================================================= -->
<div class="doc_subsection">
  <a name="int_debugger">Debugger Intrinsics</a>
</div>

<div class="doc_text">
<p>
The LLVM debugger intrinsics (which all start with <tt>llvm.dbg.</tt> prefix),
are described in the <a
href="SourceLevelDebugging.html#format_common_intrinsics">LLVM Source Level
Debugging</a> document.
</p>
</div>


<!-- ======================================================================= -->
<div class="doc_subsection">
  <a name="int_eh">Exception Handling Intrinsics</a>
</div>

<div class="doc_text">
<p> The LLVM exception handling intrinsics (which all start with
<tt>llvm.eh.</tt> prefix), are described in the <a
href="ExceptionHandling.html#format_common_intrinsics">LLVM Exception
Handling</a> document. </p>
</div>

<!-- ======================================================================= -->
<div class="doc_subsection">
  <a name="int_atomics">Atomic Operations and Synchronization Intrinsics</a>
</div>

<div class="doc_text">
<p>
  These intrinsic functions expand the "universal IR" of LLVM to represent 
  hardware constructs for atomic operations and memory synchronization.  This 
  provides an interface to the hardware, not an interface to the programmer. It 
  is aimed at a low enough level to allow any programming models or APIs which 
  need atomic behaviors to map cleanly onto it. It is also modeled primarily on 
  hardware behavior. Just as hardware provides a "unviresal IR" for source 
  languages, it also provides a starting point for developing a "universal" 
  atomic operation and synchronization IR.
</p>
<p>
  These do <em>not</em> form an API such as high-level threading libraries, 
  software transaction memory systems, atomic primitives, and intrinsic 
  functionss as found in BSD, GNU libc, atomic_ops, APR, and other system and 
  application libraries.  The hardware interface provided by LLVM should allow 
  a clean implementation of all of these APIs and parallel programming models. 
  No one model or paradigm should be selected above others unless the hardware 
  itself ubiquitously does so.
</p>
</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
  <a name="int_lcs">'<tt>llvm.atomic.lcs.*</tt>' Intrinsic</a>
</div>
<div class="doc_text">
<h5>Syntax:</h5>
<p>
  This is an overloaded intrinsic. You can use <tt>llvm.atomic.lcs</tt> on any 
  integer bit width. Not all targets support all bit widths however.
<pre>
declare i8 @llvm.atomic.lcs.i8.i8p.i8.i8( i8* &lt;ptr&gt;, i8 &lt;cmp&gt;, i8 &lt;val&gt; )
declare i16 @llvm.atomic.lcs.i16.i16p.i16.i16( i16* &lt;ptr&gt;, i16 &lt;cmp&gt;, i16 &lt;val&gt; )
declare i32 @llvm.atomic.lcs.i32.i32p.i32.i32( i32* &lt;ptr&gt;, i32 &lt;cmp&gt;, i32 &lt;val&gt; )
declare i64 @llvm.atomic.lcs.i64.i64p.i64.i64( i64* &lt;ptr&gt;, i64 &lt;cmp&gt;, i64 &lt;val&gt; )
</pre>
</p>
<h5>Overview:</h5>
<p>
  This loads a value in shared memory and compares it to a given value. If they 
  are equal, it stores a new value into the shared memory.
</p>
<h5>Arguments:</h5>
<p>
  The <tt>llvm.atomic.lcs</tt> intrinsic takes three arguments. The result as 
  well as both <tt>cmp</tt> and <tt>val</tt> must be integer values with the 
  same bit width. The <tt>ptr</tt> argument must be a pointer to a value of 
  this integer type. While any bit width integer may be used, targets may only 
  lower representations they support in hardware.
</p>
<h5>Semantics:</h5>
<p>
  This entire intrinsic must be executed atomically. It first loads the value 
  in shared memory pointed to by <tt>ptr</tt> and compares it with the value 
  <tt>cmp</tt>. If they are equal, <tt>val</tt> is stored into the shared 
  memory. The loaded value is yielded in all cases. This provides the 
  equivalent of an atomic compare-and-swap operation within the SSA framework.
</p>
<h5>Examples:</h5>
<pre>
%ptr      = malloc i32
            store i32 4, %ptr

%val1     = add i32 4, 4
%result1  = call i32 @llvm.atomic.lcs( i32* %ptr, i32 4, %val1 )
                                          <i>; yields {i32}:result1 = 4</i>
%stored1  = icmp eq i32 %result1, 4       <i>; yields {i1}:stored1 = true</i>
%memval1  = load i32* %ptr                <i>; yields {i32}:memval1 = 8</i>

%val2     = add i32 1, 1
%result2  = call i32 @llvm.atomic.lcs( i32* %ptr, i32 5, %val2 )
                                          <i>; yields {i32}:result2 = 8</i>
%stored2  = icmp eq i32 %result2, 5       <i>; yields {i1}:stored2 = false</i>
%memval2  = load i32* %ptr                <i>; yields {i32}:memval2 = 8</i>
</pre>
</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
  <a name="int_ls">'<tt>llvm.atomic.ls.*</tt>' Intrinsic</a>
</div>
<div class="doc_text">
<h5>Syntax:</h5>
<p>
  This is an overloaded intrinsic. You can use <tt>llvm.atomic.ls</tt> on any 
  integer bit width. Not all targets support all bit widths however.
<pre>
declare i8 @llvm.atomic.ls.i8.i8p.i8( i8* &lt;ptr&gt;, i8 &lt;val&gt; )
declare i16 @llvm.atomic.ls.i16.i16p.i16( i16* &lt;ptr&gt;, i16 &lt;val&gt; )
declare i32 @llvm.atomic.ls.i32.i32p.i32( i32* &lt;ptr&gt;, i32 &lt;val&gt; )
declare i64 @llvm.atomic.ls.i64.i64p.i64( i64* &lt;ptr&gt;, i64 &lt;val&gt; )
</pre>
</p>
<h5>Overview:</h5>
<p>
  This intrinsic loads the value stored in shared memory at <tt>ptr</tt> and 
  yields the value from memory. It then stores the value in <tt>val</tt> in the 
  shared memory at <tt>ptr</tt>.
</p>
<h5>Arguments:</h5>
<p>
  The <tt>llvm.atomic.ls</tt> intrinsic takes two arguments. Both the 
  <tt>val</tt> argument and the result must be integers of the same bit width. 
  The first argument, <tt>ptr</tt>, must be a pointer to a value of this 
  integer type. The targets may only lower integer representations they 
  support.
</p>
<h5>Semantics:</h5>
<p>
  This intrinsic loads the value pointed to by <tt>ptr</tt>, yields it, and 
  stores <tt>val</tt> back into <tt>ptr</tt> atomically. This provides the 
  equivalent of an atomic swap operation within the SSA framework.
</p>
<h5>Examples:</h5>
<pre>
%ptr      = malloc i32
            store i32 4, %ptr

%val1     = add i32 4, 4
%result1  = call i32 @llvm.atomic.ls( i32* %ptr, i32 %val1 )
                                        <i>; yields {i32}:result1 = 4</i>
%stored1  = icmp eq i32 %result1, 4     <i>; yields {i1}:stored1 = true</i>
%memval1  = load i32* %ptr              <i>; yields {i32}:memval1 = 8</i>

%val2     = add i32 1, 1
%result2  = call i32 @llvm.atomic.ls( i32* %ptr, i32 %val2 )
                                        <i>; yields {i32}:result2 = 8</i>
%stored2  = icmp eq i32 %result2, 8     <i>; yields {i1}:stored2 = true</i>
%memval2  = load i32* %ptr              <i>; yields {i32}:memval2 = 2</i>
</pre>
 </div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
  <a name="int_las">'<tt>llvm.atomic.las.*</tt>' Intrinsic</a>
</div>
<div class="doc_text">
<h5>Syntax:</h5>
<p>
  This is an overloaded intrinsic. You can use <tt>llvm.atomic.las</tt> on any 
  integer bit width. Not all targets support all bit widths however.
<pre>
declare i8 @llvm.atomic.las.i8.i8p.i8( i8* &lt;ptr&gt;, i8 &lt;delta&gt; )
declare i16 @llvm.atomic.las.i16.i16p.i16( i16* &lt;ptr&gt;, i16 &lt;delta&gt; )
declare i32 @llvm.atomic.las.i32.i32p.i32( i32* &lt;ptr&gt;, i32 &lt;delta&gt; )
declare i64 @llvm.atomic.las.i64.i64p.i64( i64* &lt;ptr&gt;, i64 &lt;delta&gt; )
</pre>
</p>
<h5>Overview:</h5>
<p>
  This intrinsic adds <tt>delta</tt> to the value stored in shared memory at 
  <tt>ptr</tt>. It yields the original value at <tt>ptr</tt>.
</p>
<h5>Arguments:</h5>
<p>
  The intrinsic takes two arguments, the first a pointer to an integer value 
  and the second an integer value. The result is also an integer value. These 
  integer types can have any bit width, but they must all have the same bit 
  width. The targets may only lower integer representations they support.
</p>
<h5>Semantics:</h5>
<p>
  This intrinsic does a series of operations atomically. It first loads the 
  value stored at <tt>ptr</tt>. It then adds <tt>delta</tt>, stores the result 
  to <tt>ptr</tt>. It yields the original value stored at <tt>ptr</tt>.
</p>
<h5>Examples:</h5>
<pre>
%ptr      = malloc i32
        store i32 4, %ptr
%result1  = call i32 @llvm.atomic.las( i32* %ptr, i32 4 )
                                <i>; yields {i32}:result1 = 4</i>
%result2  = call i32 @llvm.atomic.las( i32* %ptr, i32 2 )
                                <i>; yields {i32}:result2 = 8</i>
%result3  = call i32 @llvm.atomic.las( i32* %ptr, i32 5 )
                                <i>; yields {i32}:result3 = 10</i>
%memval   = load i32* %ptr      <i>; yields {i32}:memval1 = 15</i>
</pre>
</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
  <a name="int_lss">'<tt>llvm.atomic.lss.*</tt>' Intrinsic</a>
</div>
<div class="doc_text">
<h5>Syntax:</h5>
<p>
  This is an overloaded intrinsic. You can use <tt>llvm.atomic.lss</tt> on any 
  integer bit width. Not all targets support all bit widths however.
<pre>
declare i8 @llvm.atomic.lss.i8.i8.i8( i8* &lt;ptr&gt;, i8 &lt;delta&gt; )
declare i16 @llvm.atomic.lss.i16.i16.i16( i16* &lt;ptr&gt;, i16 &lt;delta&gt; )
declare i32 @llvm.atomic.lss.i32.i32.i32( i32* &lt;ptr&gt;, i32 &lt;delta&gt; )
declare i64 @llvm.atomic.lss.i64.i64.i64( i64* &lt;ptr&gt;, i64 &lt;delta&gt; )
</pre>
</p>
<h5>Overview:</h5>
<p>
  This intrinsic subtracts <tt>delta</tt> from the value stored in shared 
  memory at <tt>ptr</tt>. It yields the original value at <tt>ptr</tt>.
</p>
<h5>Arguments:</h5>
<p>
  The intrinsic takes two arguments, the first a pointer to an integer value 
  and the second an integer value. The result is also an integer value. These 
  integer types can have any bit width, but they must all have the same bit 
  width. The targets may only lower integer representations they support.
</p>
<h5>Semantics:</h5>
<p>
  This intrinsic does a series of operations atomically. It first loads the 
  value stored at <tt>ptr</tt>. It then subtracts <tt>delta</tt>, 
  stores the result to <tt>ptr</tt>. It yields the original value stored 
  at <tt>ptr</tt>.
</p>
<h5>Examples:</h5>
<pre>
%ptr      = malloc i32
        store i32 32, %ptr
%result1  = call i32 @llvm.atomic.lss( i32* %ptr, i32 4 )
                                    <i>; yields {i32}:result1 = 32</i>
%result2  = call i32 @llvm.atomic.lss( i32* %ptr, i32 2 )
                                    <i>; yields {i32}:result2 = 28</i>
%result3  = call i32 @llvm.atomic.lss( i32* %ptr, i32 5 )
                                    <i>; yields {i32}:result3 = 26</i>
%memval   = load i32* %ptr          <i>; yields {i32}:memval1 = 21</i>
</pre>
</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
  <a name="int_memory_barrier">'<tt>llvm.memory.barrier</tt>' Intrinsic</a>
</div>
<div class="doc_text">
<h5>Syntax:</h5>
<p>
<pre>
declare void @llvm.memory.barrier( i1 &lt;ll&gt;, i1 &lt;ls&gt;, i1 &lt;sl&gt;, i1 &lt;ss&gt; )
</pre>
</p>
<h5>Overview:</h5>
<p>
  The <tt>llvm.memory.barrier</tt> intrinsic guarantees ordering between 
  specific pairs of memory access types.
</p>
<h5>Arguments:</h5>
<p>
  The <tt>llvm.memory.barrier</tt> intrinsic requires four boolean arguments. 
  Each argument enables a specific barrier as listed below.
  <ul>
    <li><tt>ll</tt>: load-load barrier</li>
    <li><tt>ls</tt>: load-store barrier</li>
    <li><tt>sl</tt>: store-load barrier</li>
    <li><tt>ss</tt>: store-store barrier</li>
  </ul>
</p>
<h5>Semantics:</h5>
<p>
  This intrinsic causes the system to enforce some ordering constraints upon 
  the loads and stores of the program. This barrier does not indicate 
  <em>when</em> any events will occur, it only enforces an <em>order</em> in 
  which they occur. For any of the specified pairs of load and store operations 
  (f.ex.  load-load, or store-load), all of the first operations preceding the 
  barrier will complete before any of the second operations succeeding the 
  barrier begin. Specifically the semantics for each pairing is as follows:
  <ul>
    <li><tt>ll</tt>: All loads before the barrier must complete before any load 
    after the barrier begins.</li>
    <li><tt>ls</tt>: All loads before the barrier must complete before any 
    store after the barrier begins.</li>
    <li><tt>ss</tt>: All stores before the barrier must complete before any 
    store after the barrier begins.</li>
    <li><tt>sl</tt>: All stores before the barrier must complete before any 
    load after the barrier begins.</li>
  </ul>
  These semantics are applied with a logical "and" behavior when more than  one 
  is enabled in a single memory barrier intrinsic.
</p>
<h5>Example:</h5>
<pre>
%ptr      = malloc i32
            store i32 4, %ptr

%result1  = load i32* %ptr      <i>; yields {i32}:result1 = 4</i>
            call void @llvm.memory.barrier( i1 false, i1 true, i1 false, i1 false )
                                <i>; guarantee the above finishes</i>
            store i32 8, %ptr   <i>; before this begins</i>
</pre>
</div>

<!-- ======================================================================= -->
<div class="doc_subsection">
  <a name="int_general">General Intrinsics</a>
</div>

<div class="doc_text">
<p> This class of intrinsics is designed to be generic and has
no specific purpose. </p>
</div>

<!-- _______________________________________________________________________ -->
<div class="doc_subsubsection">
  <a name="int_var_annotation">'<tt>llvm.var.annotation</tt>' Intrinsic</a>
</div>

<div class="doc_text">

<h5>Syntax:</h5>
<pre>
  declare void @llvm.var.annotation(i8* &lt;val&gt;, i8* &lt;str&gt;, i8* &lt;str&gt;, i32  &lt;int&gt; )
</pre>

<h5>Overview:</h5>

<p>
The '<tt>llvm.var.annotation</tt>' intrinsic
</p>

<h5>Arguments:</h5>

<p>
The first argument is a pointer to a value, the second is a pointer to a 
global string, the third is a pointer to a global string which is the source 
file name, and the last argument is the line number.
</p>

<h5>Semantics:</h5>

<p>
This intrinsic allows annotation of local variables with arbitrary strings.  
This can be useful for special purpose optimizations that want to look for these
 annotations.  These have no other defined use, they are ignored by code 
 generation and optimization.
</div>


<!-- *********************************************************************** -->
<hr>
<address>
  <a href="http://jigsaw.w3.org/css-validator/check/referer"><img
  src="http://jigsaw.w3.org/css-validator/images/vcss" alt="Valid CSS!"></a>
  <a href="http://validator.w3.org/check/referer"><img
  src="http://www.w3.org/Icons/valid-html401" alt="Valid HTML 4.01!" /></a>

  <a href="mailto:sabre@nondot.org">Chris Lattner</a><br>
  <a href="http://llvm.org">The LLVM Compiler Infrastructure</a><br>
  Last modified: $Date$
</address>
</body>
</html>
generated by cgit v1.1 at 2024-12-27 22:11:00 +0000