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
5188
5189
5190
5191
5192
5193
5194
5195
5196
5197
5198
5199
5200
5201
5202
5203
5204
5205
5206
5207
5208
5209
5210
5211
5212
5213
5214
5215
5216
5217
5218
5219
5220
5221
5222
5223
5224
5225
5226
5227
5228
5229
5230
5231
5232
5233
5234
5235
5236
5237
5238
5239
5240
5241
5242
5243
5244
5245
5246
5247
5248
5249
5250
5251
5252
5253
5254
5255
5256
5257
5258
5259
5260
5261
5262
5263
5264
5265
5266
5267
5268
5269
5270
5271
5272
5273
5274
5275
5276
5277
5278
5279
5280
5281
5282
5283
5284
5285
5286
5287
5288
5289
5290
5291
5292
5293
5294
5295
5296
5297
5298
5299
5300
5301
5302
5303
5304
5305
5306
5307
5308
5309
5310
5311
5312
5313
5314
5315
5316
5317
5318
5319
5320
5321
5322
5323
5324
5325
5326
5327
5328
5329
5330
5331
5332
5333
5334
5335
5336
5337
5338
5339
5340
5341
5342
5343
5344
5345
5346
5347
5348
5349
5350
5351
5352
5353
5354
5355
5356
5357
5358
5359
5360
5361
5362
5363
5364
5365
5366
5367
5368
5369
5370
5371
5372
5373
5374
5375
5376
5377
5378
5379
5380
5381
5382
5383
5384
5385
5386
5387
5388
5389
5390
5391
5392
5393
5394
5395
5396
5397
5398
5399
5400
5401
5402
5403
5404
5405
5406
5407
5408
5409
5410
5411
5412
5413
5414
5415
5416
5417
5418
5419
5420
5421
5422
5423
5424
5425
5426
5427
5428
5429
5430
5431
5432
5433
5434
5435
5436
5437
5438
5439
5440
5441
5442
5443
5444
5445
5446
5447
5448
5449
5450
5451
5452
5453
5454
5455
5456
5457
5458
5459
5460
5461
5462
5463
5464
5465
5466
5467
5468
5469
5470
5471
5472
5473
5474
5475
5476
5477
5478
5479
5480
5481
5482
5483
5484
5485
5486
5487
5488
5489
5490
5491
5492
5493
5494
5495
5496
5497
5498
5499
5500
5501
5502
5503
5504
5505
5506
5507
5508
5509
5510
5511
5512
5513
5514
5515
5516
5517
5518
5519
5520
5521
5522
5523
5524
5525
5526
5527
5528
5529
5530
5531
5532
5533
5534
5535
5536
5537
5538
5539
5540
5541
5542
5543
5544
5545
5546
5547
5548
5549
5550
5551
5552
5553
5554
5555
5556
5557
5558
5559
5560
5561
5562
5563
5564
5565
5566
5567
5568
5569
5570
5571
5572
5573
5574
5575
5576
5577
5578
5579
5580
5581
5582
5583
5584
5585
5586
5587
5588
5589
5590
5591
5592
5593
5594
5595
5596
5597
5598
5599
5600
5601
5602
5603
5604
5605
5606
5607
5608
5609
5610
5611
5612
5613
5614
5615
5616
5617
5618
5619
5620
5621
5622
5623
5624
5625
5626
5627
5628
5629
5630
5631
5632
5633
5634
5635
5636
5637
5638
5639
5640
5641
5642
5643
5644
5645
5646
5647
5648
5649
5650
5651
5652
5653
5654
5655
5656
5657
5658
5659
5660
5661
5662
5663
5664
5665
5666
5667
5668
5669
5670
5671
5672
5673
5674
5675
5676
5677
5678
5679
5680
5681
5682
5683
5684
5685
5686
5687
5688
5689
5690
5691
5692
5693
5694
5695
5696
5697
5698
5699
5700
5701
5702
5703
5704
5705
5706
5707
5708
5709
5710
5711
5712
5713
5714
5715
5716
5717
5718
5719
5720
5721
5722
5723
5724
5725
5726
5727
5728
5729
5730
5731
5732
5733
5734
5735
5736
5737
5738
5739
5740
5741
5742
5743
5744
5745
5746
5747
5748
5749
5750
5751
5752
5753
5754
5755
5756
5757
5758
5759
5760
5761
5762
5763
5764
5765
5766
5767
5768
5769
5770
5771
5772
5773
5774
5775
5776
5777
5778
5779
5780
5781
5782
5783
5784
5785
5786
5787
5788
5789
5790
5791
5792
5793
5794
5795
5796
5797
5798
5799
5800
5801
5802
5803
5804
5805
5806
5807
5808
5809
5810
5811
5812
5813
5814
5815
5816
5817
5818
5819
5820
5821
5822
5823
5824
5825
5826
5827
5828
5829
5830
5831
5832
5833
5834
5835
5836
5837
5838
5839
5840
5841
5842
5843
5844
5845
5846
5847
5848
5849
5850
5851
5852
5853
5854
5855
5856
5857
5858
5859
5860
5861
5862
5863
5864
5865
5866
5867
5868
5869
5870
5871
5872
5873
5874
5875
5876
5877
5878
5879
5880
5881
5882
5883
5884
5885
5886
5887
5888
5889
5890
5891
5892
5893
5894
5895
5896
5897
5898
5899
5900
5901
5902
5903
5904
5905
5906
5907
5908
5909
5910
5911
5912
5913
5914
5915
5916
5917
5918
5919
5920
5921
5922
5923
5924
5925
5926
5927
5928
5929
5930
5931
5932
5933
5934
5935
5936
5937
5938
5939
5940
5941
5942
5943
5944
5945
5946
5947
5948
5949
5950
5951
5952
5953
5954
5955
5956
5957
5958
5959
5960
5961
5962
5963
5964
5965
5966
5967
5968
5969
5970
5971
5972
5973
5974
5975
5976
5977
5978
5979
5980
5981
5982
5983
5984
5985
5986
5987
5988
5989
5990
5991
5992
5993
5994
5995
5996
5997
5998
5999
6000
6001
6002
6003
6004
6005
6006
6007
6008
6009
6010
6011
6012
6013
6014
6015
6016
6017
6018
6019
6020
6021
6022
6023
6024
6025
6026
6027
6028
6029
6030
6031
6032
6033
6034
6035
6036
6037
6038
6039
6040
6041
6042
6043
6044
6045
6046
6047
6048
6049
6050
6051
6052
6053
6054
6055
6056
6057
6058
6059
6060
6061
6062
6063
6064
6065
6066
6067
6068
6069
6070
6071
6072
6073
6074
6075
6076
6077
6078
6079
6080
6081
6082
6083
6084
6085
6086
6087
6088
6089
6090
6091
6092
6093
6094
6095
6096
6097
6098
6099
6100
6101
6102
6103
6104
6105
6106
6107
6108
6109
6110
6111
6112
6113
6114
6115
6116
6117
6118
6119
6120
6121
6122
6123
6124
6125
6126
6127
6128
6129
6130
6131
6132
6133
6134
6135
6136
6137
6138
6139
6140
6141
6142
6143
6144
6145
6146
6147
6148
6149
6150
6151
6152
6153
6154
6155
6156
6157
6158
6159
6160
6161
6162
6163
6164
6165
6166
6167
6168
6169
6170
6171
6172
6173
6174
6175
6176
6177
6178
6179
6180
6181
6182
6183
6184
6185
6186
6187
6188
6189
6190
6191
6192
6193
6194
6195
6196
6197
6198
6199
6200
6201
6202
6203
6204
6205
6206
6207
6208
6209
6210
6211
6212
6213
6214
6215
6216
6217
6218
6219
6220
6221
6222
6223
6224
6225
6226
6227
6228
6229
6230
6231
6232
6233
6234
6235
6236
6237
6238
6239
6240
6241
6242
6243
6244
6245
6246
6247
6248
6249
6250
6251
6252
6253
6254
6255
6256
6257
6258
6259
6260
6261
6262
6263
6264
6265
6266
6267
6268
6269
6270
6271
6272
6273
6274
6275
6276
6277
6278
6279
6280
6281
6282
6283
6284
6285
6286
6287
6288
6289
6290
6291
6292
6293
6294
6295
6296
6297
6298
6299
6300
6301
6302
6303
6304
6305
6306
6307
6308
6309
6310
6311
6312
6313
6314
6315
6316
6317
6318
6319
6320
6321
6322
6323
6324
6325
6326
6327
6328
6329
6330
6331
6332
6333
6334
6335
6336
6337
6338
6339
6340
6341
6342
6343
6344
6345
6346
6347
6348
6349
6350
6351
6352
6353
6354
6355
6356
6357
6358
6359
6360
6361
6362
6363
6364
6365
6366
6367
6368
6369
6370
6371
6372
6373
6374
6375
6376
6377
6378
6379
6380
6381
6382
6383
6384
6385
6386
6387
6388
6389
6390
6391
6392
6393
6394
6395
6396
6397
6398
6399
6400
6401
6402
6403
6404
6405
6406
6407
6408
6409
6410
6411
6412
6413
6414
6415
6416
6417
6418
6419
6420
6421
6422
6423
6424
6425
6426
6427
6428
6429
6430
6431
6432
6433
6434
6435
6436
6437
6438
6439
6440
6441
6442
6443
6444
6445
6446
6447
6448
6449
6450
6451
6452
6453
6454
6455
6456
6457
6458
6459
6460
6461
6462
6463
6464
6465
6466
6467
6468
6469
6470
6471
6472
6473
6474
6475
6476
6477
6478
6479
6480
6481
6482
6483
6484
6485
6486
6487
6488
6489
6490
6491
6492
6493
6494
6495
6496
6497
6498
6499
6500
6501
6502
6503
6504
6505
6506
6507
6508
6509
6510
6511
6512
6513
6514
6515
6516
6517
6518
6519
6520
6521
6522
6523
6524
6525
6526
6527
6528
6529
6530
6531
6532
6533
6534
6535
6536
6537
6538
6539
6540
6541
6542
6543
6544
6545
6546
6547
6548
6549
6550
6551
6552
6553
6554
6555
6556
6557
6558
6559
6560
6561
6562
6563
6564
6565
6566
6567
6568
6569
6570
6571
6572
6573
6574
6575
6576
6577
6578
6579
6580
6581
6582
6583
6584
6585
6586
6587
6588
6589
6590
6591
6592
6593
6594
6595
6596
6597
6598
6599
6600
6601
6602
6603
6604
6605
6606
6607
6608
6609
6610
6611
6612
6613
6614
6615
6616
6617
6618
6619
6620
6621
6622
6623
6624
6625
6626
6627
6628
6629
6630
6631
6632
6633
6634
6635
6636
6637
6638
6639
6640
6641
6642
6643
6644
6645
6646
6647
6648
6649
6650
6651
6652
6653
6654
6655
6656
6657
6658
6659
6660
6661
6662
6663
6664
6665
6666
6667
6668
6669
6670
6671
6672
6673
6674
6675
6676
6677
6678
6679
6680
6681
6682
6683
6684
6685
6686
6687
6688
6689
6690
6691
6692
6693
6694
6695
6696
6697
6698
6699
6700
6701
6702
6703
6704
6705
6706
6707
6708
6709
6710
6711
6712
6713
6714
6715
6716
6717
6718
6719
6720
6721
6722
6723
6724
6725
6726
6727
6728
6729
6730
6731
6732
6733
6734
6735
6736
6737
6738
6739
6740
6741
6742
6743
6744
6745
6746
6747
6748
6749
6750
6751
6752
6753
6754
6755
6756
6757
6758
6759
6760
6761
6762
6763
6764
6765
6766
6767
6768
6769
6770
6771
6772
6773
6774
6775
6776
6777
6778
6779
6780
6781
6782
6783
6784
6785
6786
6787
6788
6789
6790
6791
6792
6793
6794
6795
6796
6797
6798
6799
6800
6801
6802
6803
6804
6805
6806
6807
6808
6809
6810
6811
6812
6813
6814
6815
6816
6817
6818
6819
6820
6821
6822
6823
6824
6825
6826
6827
6828
6829
6830
6831
6832
6833
6834
6835
6836
6837
6838
6839
6840
6841
6842
6843
6844
6845
6846
6847
6848
6849
6850
6851
6852
6853
6854
6855
6856
6857
6858
6859
6860
6861
6862
6863
6864
6865
6866
6867
6868
6869
6870
6871
6872
6873
6874
6875
6876
6877
6878
6879
6880
6881
6882
6883
6884
6885
6886
6887
6888
6889
6890
6891
6892
6893
6894
6895
6896
6897
6898
6899
6900
6901
6902
6903
6904
6905
6906
6907
6908
6909
6910
6911
6912
6913
6914
6915
6916
6917
6918
6919
6920
6921
6922
6923
6924
6925
6926
6927
6928
6929
6930
6931
6932
6933
6934
6935
6936
6937
6938
6939
6940
6941
6942
6943
6944
6945
6946
6947
6948
6949
6950
6951
6952
6953
6954
6955
6956
6957
6958
6959
6960
6961
6962
6963
6964
6965
6966
6967
6968
6969
6970
6971
6972
6973
6974
6975
6976
6977
6978
6979
6980
6981
6982
6983
6984
6985
6986
6987
6988
6989
6990
6991
6992
6993
6994
6995
6996
6997
6998
6999
7000
7001
7002
7003
7004
7005
7006
7007
7008
7009
7010
7011
7012
7013
7014
7015
7016
7017
7018
7019
7020
7021
7022
7023
7024
7025
7026
7027
7028
7029
7030
7031
7032
7033
7034
7035
7036
7037
7038
7039
7040
7041
7042
7043
7044
7045
7046
7047
7048
7049
7050
7051
7052
7053
7054
7055
7056
7057
7058
7059
7060
7061
7062
7063
7064
7065
7066
7067
7068
7069
7070
7071
7072
7073
7074
7075
7076
7077
7078
7079
7080
7081
7082
7083
7084
7085
7086
7087
7088
7089
7090
7091
7092
7093
7094
7095
7096
7097
7098
7099
7100
7101
7102
7103
7104
7105
7106
7107
7108
7109
7110
7111
7112
7113
7114
7115
7116
7117
7118
7119
7120
7121
7122
7123
7124
7125
7126
7127
7128
7129
7130
7131
7132
7133
7134
7135
7136
7137
7138
7139
7140
7141
7142
7143
7144
7145
7146
7147
7148
7149
7150
7151
7152
7153
7154
7155
7156
7157
7158
7159
7160
7161
7162
7163
7164
7165
7166
7167
7168
7169
7170
7171
7172
7173
7174
7175
7176
7177
7178
7179
7180
7181
7182
7183
7184
7185
7186
7187
7188
7189
7190
7191
7192
7193
7194
7195
7196
7197
7198
7199
7200
7201
7202
7203
7204
7205
7206
7207
7208
7209
7210
7211
7212
7213
7214
7215
7216
7217
7218
7219
7220
7221
7222
7223
7224
7225
7226
7227
7228
7229
7230
7231
7232
7233
7234
7235
7236
7237
7238
7239
7240
7241
7242
7243
7244
7245
7246
7247
7248
7249
7250
7251
7252
7253
7254
7255
7256
7257
7258
7259
7260
7261
7262
7263
7264
7265
7266
7267
7268
7269
7270
7271
7272
7273
7274
7275
7276
7277
7278
7279
7280
7281
7282
7283
7284
7285
7286
7287
7288
7289
7290
7291
7292
7293
7294
7295
7296
7297
7298
7299
7300
7301
7302
7303
7304
7305
7306
7307
7308
7309
7310
7311
7312
7313
7314
7315
7316
7317
7318
7319
7320
7321
7322
7323
7324
7325
7326
7327
7328
7329
7330
7331
7332
7333
7334
7335
7336
7337
7338
7339
7340
7341
7342
7343
7344
7345
7346
7347
7348
7349
7350
7351
7352
7353
7354
7355
7356
7357
7358
7359
7360
7361
7362
7363
7364
7365
7366
7367
7368
7369
7370
7371
7372
7373
7374
7375
7376
7377
7378
7379
7380
7381
7382
7383
7384
7385
7386
7387
7388
7389
7390
7391
7392
7393
7394
7395
7396
7397
7398
7399
7400
7401
7402
7403
7404
7405
7406
7407
7408
7409
7410
7411
7412
7413
7414
7415
7416
7417
7418
7419
7420
7421
7422
7423
7424
7425
7426
7427
7428
7429
7430
7431
7432
7433
7434
7435
7436
7437
7438
7439
7440
7441
7442
7443
7444
7445
7446
7447
7448
7449
7450
7451
7452
7453
7454
7455
7456
7457
7458
7459
7460
7461
7462
7463
7464
7465
7466
7467
7468
7469
7470
7471
7472
7473
7474
7475
7476
7477
7478
7479
7480
7481
7482
7483
7484
7485
7486
7487
7488
7489
7490
7491
7492
7493
7494
7495
7496
7497
7498
7499
7500
7501
7502
7503
7504
7505
7506
7507
7508
7509
7510
7511
7512
7513
7514
7515
7516
7517
7518
7519
7520
7521
7522
7523
7524
7525
7526
7527
7528
7529
7530
7531
7532
7533
7534
7535
7536
7537
7538
7539
7540
7541
7542
7543
7544
7545
7546
7547
7548
7549
7550
7551
7552
7553
7554
7555
7556
7557
7558
7559
7560
7561
7562
7563
7564
7565
7566
7567
7568
7569
7570
7571
7572
7573
7574
7575
7576
7577
7578
7579
7580
7581
7582
7583
7584
7585
7586
7587
7588
7589
7590
7591
7592
7593
7594
7595
7596
7597
7598
7599
7600
7601
7602
7603
7604
7605
7606
7607
7608
7609
7610
7611
7612
7613
7614
7615
7616
7617
7618
7619
7620
7621
7622
7623
7624
7625
7626
7627
7628
7629
7630
7631
7632
7633
7634
7635
7636
7637
7638
7639
7640
7641
7642
7643
7644
7645
7646
7647
7648
7649
7650
7651
7652
7653
7654
7655
7656
7657
7658
7659
7660
7661
7662
7663
7664
7665
7666
7667
7668
7669
7670
7671
7672
7673
7674
7675
7676
7677
7678
7679
7680
7681
7682
7683
7684
7685
7686
7687
7688
7689
7690
7691
7692
7693
7694
7695
7696
7697
7698
7699
7700
7701
7702
7703
7704
7705
7706
7707
7708
7709
7710
7711
7712
7713
7714
7715
7716
7717
7718
7719
7720
7721
7722
7723
7724
7725
7726
7727
7728
7729
7730
7731
7732
7733
7734
7735
7736
7737
7738
7739
7740
7741
7742
7743
7744
7745
7746
7747
7748
7749
7750
7751
7752
7753
7754
7755
7756
7757
7758
7759
7760
7761
7762
7763
7764
7765
7766
7767
7768
7769
7770
7771
7772
7773
7774
7775
7776
7777
7778
7779
7780
7781
7782
7783
7784
7785
7786
7787
7788
7789
7790
7791
7792
7793
7794
7795
7796
7797
7798
7799
7800
7801
7802
7803
7804
7805
7806
7807
7808
7809
7810
7811
7812
7813
7814
7815
7816
7817
7818
7819
7820
7821
7822
7823
7824
7825
7826
7827
7828
7829
7830
7831
7832
7833
7834
7835
7836
7837
7838
7839
7840
7841
7842
7843
7844
7845
7846
7847
7848
7849
7850
7851
7852
7853
7854
7855
7856
7857
7858
7859
7860
7861
7862
7863
7864
7865
7866
7867
7868
7869
7870
7871
7872
7873
7874
7875
7876
7877
7878
7879
7880
7881
7882
7883
7884
7885
7886
7887
7888
7889
7890
7891
7892
7893
7894
7895
7896
7897
7898
7899
7900
7901
7902
7903
7904
7905
7906
7907
7908
7909
7910
7911
7912
7913
7914
7915
7916
7917
7918
7919
7920
7921
7922
7923
7924
7925
7926
7927
7928
7929
7930
7931
7932
7933
7934
7935
7936
7937
7938
7939
7940
7941
7942
7943
7944
7945
7946
7947
7948
7949
7950
7951
7952
7953
7954
7955
7956
7957
7958
7959
7960
7961
7962
7963
7964
7965
7966
7967
7968
7969
7970
7971
7972
7973
7974
7975
7976
7977
7978
7979
7980
7981
7982
7983
7984
7985
7986
7987
7988
7989
7990
7991
7992
7993
7994
7995
7996
7997
7998
7999
8000
8001
8002
8003
8004
8005
8006
8007
8008
8009
8010
8011
8012
8013
8014
8015
8016
8017
8018
8019
8020
8021
8022
8023
8024
8025
8026
8027
8028
8029
8030
8031
8032
8033
8034
8035
8036
8037
8038
8039
8040
8041
8042
8043
8044
8045
8046
8047
8048
8049
8050
8051
8052
8053
8054
8055
8056
8057
8058
8059
8060
8061
8062
8063
8064
8065
8066
8067
8068
8069
8070
8071
8072
8073
8074
8075
8076
8077
8078
8079
8080
8081
8082
8083
8084
8085
8086
8087
8088
8089
8090
8091
8092
8093
8094
8095
8096
8097
8098
8099
8100
8101
8102
8103
8104
8105
8106
8107
8108
8109
8110
8111
8112
8113
8114
8115
8116
8117
8118
8119
8120
8121
8122
8123
8124
8125
8126
8127
8128
8129
8130
8131
8132
8133
8134
8135
8136
8137
8138
8139
8140
8141
8142
8143
8144
8145
8146
8147
8148
8149
8150
8151
8152
8153
8154
8155
8156
8157
8158
8159
8160
8161
8162
8163
8164
8165
8166
8167
8168
8169
8170
8171
8172
8173
8174
8175
8176
8177
8178
8179
8180
8181
8182
8183
8184
8185
8186
8187
8188
8189
8190
8191
8192
8193
8194
8195
8196
8197
8198
8199
8200
8201
8202
8203
8204
8205
8206
8207
8208
8209
8210
8211
8212
8213
8214
8215
8216
8217
8218
8219
8220
8221
8222
8223
8224
8225
8226
8227
8228
8229
8230
8231
8232
8233
8234
8235
8236
8237
8238
8239
8240
8241
8242
8243
8244
8245
8246
8247
8248
8249
8250
8251
8252
8253
8254
8255
8256
8257
8258
8259
8260
8261
8262
8263
8264
8265
8266
8267
8268
8269
8270
8271
8272
8273
8274
8275
8276
8277
8278
8279
8280
8281
8282
8283
8284
8285
8286
8287
8288
8289
8290
8291
8292
8293
8294
8295
8296
8297
8298
8299
8300
8301
8302
8303
8304
8305
8306
8307
8308
8309
8310
8311
8312
8313
8314
8315
8316
8317
8318
8319
8320
8321
8322
8323
8324
8325
8326
8327
8328
8329
8330
8331
8332
8333
8334
8335
8336
8337
8338
8339
8340
8341
8342
8343
8344
8345
8346
8347
8348
8349
8350
8351
8352
8353
8354
8355
8356
8357
8358
8359
8360
8361
8362
8363
8364
8365
8366
8367
8368
8369
8370
8371
8372
8373
8374
8375
8376
8377
8378
8379
8380
8381
8382
8383
8384
8385
8386
8387
8388
8389
8390
8391
8392
8393
8394
8395
8396
8397
8398
8399
8400
8401
8402
8403
8404
8405
8406
8407
8408
8409
8410
8411
8412
8413
8414
8415
8416
8417
8418
8419
8420
8421
8422
8423
8424
8425
8426
8427
8428
8429
8430
8431
8432
8433
8434
8435
8436
8437
8438
8439
8440
8441
8442
8443
8444
8445
8446
8447
8448
8449
8450
8451
8452
8453
8454
8455
8456
8457
8458
8459
8460
8461
8462
8463
8464
8465
8466
8467
8468
8469
8470
8471
8472
8473
8474
8475
8476
8477
8478
8479
8480
8481
8482
8483
8484
8485
8486
8487
8488
8489
8490
8491
8492
8493
8494
8495
8496
8497
8498
8499
8500
8501
8502
8503
8504
8505
8506
8507
8508
8509
8510
8511
8512
8513
8514
8515
8516
8517
8518
8519
8520
8521
8522
8523
8524
8525
8526
8527
8528
8529
8530
8531
8532
8533
8534
8535
8536
8537
8538
8539
8540
8541
8542
8543
8544
8545
8546
8547
8548
8549
8550
8551
8552
8553
8554
8555
8556
8557
8558
8559
8560
8561
8562
8563
8564
8565
8566
8567
8568
8569
8570
8571
8572
8573
8574
8575
8576
8577
8578
8579
8580
8581
8582
8583
8584
8585
8586
8587
8588
8589
8590
8591
8592
8593
8594
8595
8596
8597
8598
8599
8600
8601
8602
8603
8604
8605
8606
8607
8608
8609
8610
8611
8612
8613
8614
8615
8616
8617
8618
8619
8620
8621
8622
8623
8624
8625
8626
8627
8628
8629
8630
8631
8632
8633
8634
8635
8636
8637
8638
8639
8640
8641
8642
8643
8644
8645
8646
8647
8648
8649
8650
8651
8652
8653
8654
8655
8656
8657
8658
8659
8660
8661
8662
8663
8664
8665
8666
8667
8668
8669
8670
8671
8672
8673
8674
8675
8676
8677
8678
8679
8680
8681
8682
8683
8684
8685
8686
8687
8688
8689
8690
8691
8692
8693
8694
8695
8696
8697
8698
8699
8700
8701
8702
8703
8704
8705
8706
8707
8708
8709
8710
8711
8712
8713
8714
8715
8716
8717
8718
8719
8720
8721
8722
8723
8724
8725
8726
8727
8728
8729
8730
8731
|
<!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="_static/llvm.css" type="text/css">
</head>
<body>
<h1>LLVM Language Reference Manual</h1>
<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>
<ol>
<li><a href="#linkage_private">'<tt>private</tt>' Linkage</a></li>
<li><a href="#linkage_linker_private">'<tt>linker_private</tt>' Linkage</a></li>
<li><a href="#linkage_linker_private_weak">'<tt>linker_private_weak</tt>' Linkage</a></li>
<li><a href="#linkage_internal">'<tt>internal</tt>' Linkage</a></li>
<li><a href="#linkage_available_externally">'<tt>available_externally</tt>' Linkage</a></li>
<li><a href="#linkage_linkonce">'<tt>linkonce</tt>' Linkage</a></li>
<li><a href="#linkage_common">'<tt>common</tt>' Linkage</a></li>
<li><a href="#linkage_weak">'<tt>weak</tt>' Linkage</a></li>
<li><a href="#linkage_appending">'<tt>appending</tt>' Linkage</a></li>
<li><a href="#linkage_externweak">'<tt>extern_weak</tt>' Linkage</a></li>
<li><a href="#linkage_linkonce_odr">'<tt>linkonce_odr</tt>' Linkage</a></li>
<li><a href="#linkage_linkonce_odr_auto_hide">'<tt>linkonce_odr_auto_hide</tt>' Linkage</a></li>
<li><a href="#linkage_weak">'<tt>weak_odr</tt>' Linkage</a></li>
<li><a href="#linkage_external">'<tt>external</tt>' Linkage</a></li>
<li><a href="#linkage_dllimport">'<tt>dllimport</tt>' Linkage</a></li>
<li><a href="#linkage_dllexport">'<tt>dllexport</tt>' Linkage</a></li>
</ol>
</li>
<li><a href="#callingconv">Calling Conventions</a></li>
<li><a href="#namedtypes">Named Types</a></li>
<li><a href="#globalvars">Global Variables</a></li>
<li><a href="#functionstructure">Functions</a></li>
<li><a href="#aliasstructure">Aliases</a></li>
<li><a href="#namedmetadatastructure">Named Metadata</a></li>
<li><a href="#paramattrs">Parameter Attributes</a></li>
<li><a href="#fnattrs">Function Attributes</a></li>
<li><a href="#gc">Garbage Collector Names</a></li>
<li><a href="#moduleasm">Module-Level Inline Assembly</a></li>
<li><a href="#datalayout">Data Layout</a></li>
<li><a href="#pointeraliasing">Pointer Aliasing Rules</a></li>
<li><a href="#volatile">Volatile Memory Accesses</a></li>
<li><a href="#memmodel">Memory Model for Concurrent Operations</a></li>
<li><a href="#ordering">Atomic Memory Ordering Constraints</a></li>
</ol>
</li>
<li><a href="#typesystem">Type System</a>
<ol>
<li><a href="#t_classifications">Type Classifications</a></li>
<li><a href="#t_primitive">Primitive Types</a>
<ol>
<li><a href="#t_integer">Integer Type</a></li>
<li><a href="#t_floating">Floating Point Types</a></li>
<li><a href="#t_x86mmx">X86mmx Type</a></li>
<li><a href="#t_void">Void Type</a></li>
<li><a href="#t_label">Label Type</a></li>
<li><a href="#t_metadata">Metadata Type</a></li>
</ol>
</li>
<li><a href="#t_derived">Derived Types</a>
<ol>
<li><a href="#t_aggregate">Aggregate Types</a>
<ol>
<li><a href="#t_array">Array Type</a></li>
<li><a href="#t_struct">Structure Type</a></li>
<li><a href="#t_opaque">Opaque Structure Types</a></li>
<li><a href="#t_vector">Vector Type</a></li>
</ol>
</li>
<li><a href="#t_function">Function Type</a></li>
<li><a href="#t_pointer">Pointer Type</a></li>
</ol>
</li>
</ol>
</li>
<li><a href="#constants">Constants</a>
<ol>
<li><a href="#simpleconstants">Simple Constants</a></li>
<li><a href="#complexconstants">Complex Constants</a></li>
<li><a href="#globalconstants">Global Variable and Function Addresses</a></li>
<li><a href="#undefvalues">Undefined Values</a></li>
<li><a href="#poisonvalues">Poison Values</a></li>
<li><a href="#blockaddress">Addresses of Basic Blocks</a></li>
<li><a href="#constantexprs">Constant Expressions</a></li>
</ol>
</li>
<li><a href="#othervalues">Other Values</a>
<ol>
<li><a href="#inlineasm">Inline Assembler Expressions</a></li>
<li><a href="#metadata">Metadata Nodes and Metadata Strings</a>
<ol>
<li><a href="#tbaa">'<tt>tbaa</tt>' Metadata</a></li>
<li><a href="#fpmath">'<tt>fpmath</tt>' Metadata</a></li>
<li><a href="#range">'<tt>range</tt>' Metadata</a></li>
</ol>
</li>
</ol>
</li>
<li><a href="#module_flags">Module Flags Metadata</a>
<ol>
<li><a href="#objc_gc_flags">Objective-C Garbage Collection Module Flags Metadata</a></li>
</ol>
</li>
<li><a href="#intrinsic_globals">Intrinsic Global Variables</a>
<ol>
<li><a href="#intg_used">The '<tt>llvm.used</tt>' Global Variable</a></li>
<li><a href="#intg_compiler_used">The '<tt>llvm.compiler.used</tt>'
Global Variable</a></li>
<li><a href="#intg_global_ctors">The '<tt>llvm.global_ctors</tt>'
Global Variable</a></li>
<li><a href="#intg_global_dtors">The '<tt>llvm.global_dtors</tt>'
Global Variable</a></li>
</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_indirectbr">'<tt>indirectbr</tt>' Instruction</a></li>
<li><a href="#i_invoke">'<tt>invoke</tt>' Instruction</a></li>
<li><a href="#i_resume">'<tt>resume</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_fadd">'<tt>fadd</tt>' Instruction</a></li>
<li><a href="#i_sub">'<tt>sub</tt>' Instruction</a></li>
<li><a href="#i_fsub">'<tt>fsub</tt>' Instruction</a></li>
<li><a href="#i_mul">'<tt>mul</tt>' Instruction</a></li>
<li><a href="#i_fmul">'<tt>fmul</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="#aggregateops">Aggregate Operations</a>
<ol>
<li><a href="#i_extractvalue">'<tt>extractvalue</tt>' Instruction</a></li>
<li><a href="#i_insertvalue">'<tt>insertvalue</tt>' Instruction</a></li>
</ol>
</li>
<li><a href="#memoryops">Memory Access and Addressing Operations</a>
<ol>
<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_fence">'<tt>fence</tt>' Instruction</a></li>
<li><a href="#i_cmpxchg">'<tt>cmpxchg</tt>' Instruction</a></li>
<li><a href="#i_atomicrmw">'<tt>atomicrmw</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>
<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>
<li><a href="#i_landingpad">'<tt>landingpad</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>
<li><a href="#int_sin">'<tt>llvm.sin.*</tt>' Intrinsic</a></li>
<li><a href="#int_cos">'<tt>llvm.cos.*</tt>' Intrinsic</a></li>
<li><a href="#int_pow">'<tt>llvm.pow.*</tt>' Intrinsic</a></li>
<li><a href="#int_exp">'<tt>llvm.exp.*</tt>' Intrinsic</a></li>
<li><a href="#int_log">'<tt>llvm.log.*</tt>' Intrinsic</a></li>
<li><a href="#int_fma">'<tt>llvm.fma.*</tt>' Intrinsic</a></li>
<li><a href="#int_fabs">'<tt>llvm.fabs.*</tt>' Intrinsic</a></li>
<li><a href="#int_floor">'<tt>llvm.floor.*</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>
</ol>
</li>
<li><a href="#int_overflow">Arithmetic with Overflow Intrinsics</a>
<ol>
<li><a href="#int_sadd_overflow">'<tt>llvm.sadd.with.overflow.*</tt> Intrinsics</a></li>
<li><a href="#int_uadd_overflow">'<tt>llvm.uadd.with.overflow.*</tt> Intrinsics</a></li>
<li><a href="#int_ssub_overflow">'<tt>llvm.ssub.with.overflow.*</tt> Intrinsics</a></li>
<li><a href="#int_usub_overflow">'<tt>llvm.usub.with.overflow.*</tt> Intrinsics</a></li>
<li><a href="#int_smul_overflow">'<tt>llvm.smul.with.overflow.*</tt> Intrinsics</a></li>
<li><a href="#int_umul_overflow">'<tt>llvm.umul.with.overflow.*</tt> Intrinsics</a></li>
</ol>
</li>
<li><a href="#spec_arithmetic">Specialised Arithmetic Intrinsics</a>
<ol>
<li><a href="#fmuladd">'<tt>llvm.fmuladd</tt> Intrinsic</a></li>
</ol>
</li>
<li><a href="#int_fp16">Half Precision Floating Point Intrinsics</a>
<ol>
<li><a href="#int_convert_to_fp16">'<tt>llvm.convert.to.fp16</tt>' Intrinsic</a></li>
<li><a href="#int_convert_from_fp16">'<tt>llvm.convert.from.fp16</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_trampoline">Trampoline Intrinsics</a>
<ol>
<li><a href="#int_it">'<tt>llvm.init.trampoline</tt>' Intrinsic</a></li>
<li><a href="#int_at">'<tt>llvm.adjust.trampoline</tt>' Intrinsic</a></li>
</ol>
</li>
<li><a href="#int_memorymarkers">Memory Use Markers</a>
<ol>
<li><a href="#int_lifetime_start">'<tt>llvm.lifetime.start</tt>' Intrinsic</a></li>
<li><a href="#int_lifetime_end">'<tt>llvm.lifetime.end</tt>' Intrinsic</a></li>
<li><a href="#int_invariant_start">'<tt>llvm.invariant.start</tt>' Intrinsic</a></li>
<li><a href="#int_invariant_end">'<tt>llvm.invariant.end</tt>' Intrinsic</a></li>
</ol>
</li>
<li><a href="#int_general">General intrinsics</a>
<ol>
<li><a href="#int_var_annotation">
'<tt>llvm.var.annotation</tt>' Intrinsic</a></li>
<li><a href="#int_annotation">
'<tt>llvm.annotation.*</tt>' Intrinsic</a></li>
<li><a href="#int_trap">
'<tt>llvm.trap</tt>' Intrinsic</a></li>
<li><a href="#int_debugtrap">
'<tt>llvm.debugtrap</tt>' Intrinsic</a></li>
<li><a href="#int_stackprotector">
'<tt>llvm.stackprotector</tt>' Intrinsic</a></li>
<li><a href="#int_objectsize">
'<tt>llvm.objectsize</tt>' Intrinsic</a></li>
<li><a href="#int_expect">
'<tt>llvm.expect</tt>' Intrinsic</a></li>
<li><a href="#int_donothing">
'<tt>llvm.donothing</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>
<!-- *********************************************************************** -->
<h2><a name="abstract">Abstract</a></h2>
<!-- *********************************************************************** -->
<div>
<p>This document is a reference manual for the LLVM assembly language. LLVM is
a Static Single Assignment (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>
<!-- *********************************************************************** -->
<h2><a name="introduction">Introduction</a></h2>
<!-- *********************************************************************** -->
<div>
<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>
<!-- _______________________________________________________________________ -->
<h4>
<a name="wellformed">Well-Formedness</a>
</h4>
<div>
<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>
<pre class="doc_code">
%x = <a href="#i_add">add</a> i32 1, %x
</pre>
<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>
</div>
<!-- Describe the typesetting conventions here. -->
<!-- *********************************************************************** -->
<h2><a name="identifiers">Identifiers</a></h2>
<!-- *********************************************************************** -->
<div>
<p>LLVM identifiers come in two basic types: global and local. Global
identifiers (functions, global variables) begin with the <tt>'@'</tt>
character. Local identifiers (register names, types) begin with
the <tt>'%'</tt> character. Additionally, there are three different formats
for identifiers, for different purposes:</p>
<ol>
<li>Named values are represented as a string of characters with their prefix.
For example, <tt>%foo</tt>, <tt>@DivisionByZero</tt>,
<tt>%a.really.long.identifier</tt>. 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. Special
characters may be escaped using <tt>"\xx"</tt> where <tt>xx</tt> is the
ASCII code for the character in hexadecimal. In this way, any character
can be used in a name value, even quotes themselves.</li>
<li>Unnamed values are represented as an unsigned numeric value with their
prefix. For example, <tt>%12</tt>, <tt>@2</tt>, <tt>%44</tt>.</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 prefix 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 prefix character (<tt>'%'</tt> or <tt>'@'</tt>).</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>
<pre class="doc_code">
%result = <a href="#i_mul">mul</a> i32 %X, 8
</pre>
<p>After strength reduction:</p>
<pre class="doc_code">
%result = <a href="#i_shl">shl</a> i32 %X, i8 3
</pre>
<p>And the hard way:</p>
<pre class="doc_code">
%0 = <a href="#i_add">add</a> i32 %X, %X <i>; yields {i32}:%0</i>
%1 = <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>
<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>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>
<!-- *********************************************************************** -->
<h2><a name="highlevel">High Level Structure</a></h2>
<!-- *********************************************************************** -->
<div>
<!-- ======================================================================= -->
<h3>
<a name="modulestructure">Module Structure</a>
</h3>
<div>
<p>LLVM programs are composed of <tt>Module</tt>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>
<pre class="doc_code">
<i>; Declare the string constant as a global constant.</i>
<a href="#identifiers">@.str</a> = <a href="#linkage_private">private</a> <a href="#globalvars">unnamed_addr</a> <a href="#globalvars">constant</a> <a href="#t_array">[13 x i8]</a> c"hello world\0A\00"
<i>; External declaration of the puts function</i>
<a href="#functionstructure">declare</a> i32 @puts(i8* <a href="#nocapture">nocapture</a>) <a href="#fnattrs">nounwind</a>
<i>; Definition of main function</i>
define i32 @main() { <i>; i32()* </i>
<i>; Convert [13 x i8]* to i8 *...</i>
%cast210 = <a href="#i_getelementptr">getelementptr</a> [13 x i8]* @.str, i64 0, i64 0
<i>; Call puts function to write out the string to stdout.</i>
<a href="#i_call">call</a> i32 @puts(i8* %cast210)
<a href="#i_ret">ret</a> i32 0
}
<i>; Named metadata</i>
!1 = metadata !{i32 42}
!foo = !{!1, null}
</pre>
<p>This example is made up of a <a href="#globalvars">global variable</a> named
"<tt>.str</tt>", an external declaration of the "<tt>puts</tt>" function,
a <a href="#functionstructure">function definition</a> for
"<tt>main</tt>" and <a href="#namedmetadatastructure">named metadata</a>
"<tt>foo</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>
<!-- ======================================================================= -->
<h3>
<a name="linkage">Linkage Types</a>
</h3>
<div>
<p>All Global Variables and Functions have one of the following types of
linkage:</p>
<dl>
<dt><tt><b><a name="linkage_private">private</a></b></tt></dt>
<dd>Global values with "<tt>private</tt>" linkage are only directly accessible
by objects in the current module. In particular, linking code into a
module with an private global value may cause the private to be renamed as
necessary to avoid collisions. Because the symbol is private to the
module, all references can be updated. This doesn't show up in any symbol
table in the object file.</dd>
<dt><tt><b><a name="linkage_linker_private">linker_private</a></b></tt></dt>
<dd>Similar to <tt>private</tt>, but the symbol is passed through the
assembler and evaluated by the linker. Unlike normal strong symbols, they
are removed by the linker from the final linked image (executable or
dynamic library).</dd>
<dt><tt><b><a name="linkage_linker_private_weak">linker_private_weak</a></b></tt></dt>
<dd>Similar to "<tt>linker_private</tt>", but the symbol is weak. Note that
<tt>linker_private_weak</tt> symbols are subject to coalescing by the
linker. The symbols are removed by the linker from the final linked image
(executable or dynamic library).</dd>
<dt><tt><b><a name="linkage_internal">internal</a></b></tt></dt>
<dd>Similar to private, but the value shows as a local symbol
(<tt>STB_LOCAL</tt> in the case of ELF) in the object file. This
corresponds to the notion of the '<tt>static</tt>' keyword in C.</dd>
<dt><tt><b><a name="linkage_available_externally">available_externally</a></b></tt></dt>
<dd>Globals with "<tt>available_externally</tt>" linkage are never emitted
into the object file corresponding to the LLVM module. They exist to
allow inlining and other optimizations to take place given knowledge of
the definition of the global, which is known to be somewhere outside the
module. Globals with <tt>available_externally</tt> linkage are allowed to
be discarded at will, and are otherwise the same as <tt>linkonce_odr</tt>.
This linkage type is only allowed on definitions, not declarations.</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 can be used to implement
some forms of inline functions, templates, or other code which must be
generated in each translation unit that uses it, but where the body may
be overridden with a more definitive definition later. Unreferenced
<tt>linkonce</tt> globals are allowed to be discarded. Note that
<tt>linkonce</tt> linkage does not actually allow the optimizer to
inline the body of this function into callers because it doesn't know if
this definition of the function is the definitive definition within the
program or whether it will be overridden by a stronger definition.
To enable inlining and other optimizations, use "<tt>linkonce_odr</tt>"
linkage.</dd>
<dt><tt><b><a name="linkage_weak">weak</a></b></tt></dt>
<dd>"<tt>weak</tt>" linkage has the same merging semantics as
<tt>linkonce</tt> linkage, except that unreferenced globals with
<tt>weak</tt> linkage may not be discarded. This is used for globals that
are declared "weak" in C source code.</dd>
<dt><tt><b><a name="linkage_common">common</a></b></tt></dt>
<dd>"<tt>common</tt>" linkage is most similar to "<tt>weak</tt>" linkage, but
they are used for tentative definitions in C, such as "<tt>int X;</tt>" at
global scope.
Symbols with "<tt>common</tt>" linkage are merged in the same way as
<tt>weak symbols</tt>, and they may not be deleted if unreferenced.
<tt>common</tt> symbols may not have an explicit section,
must have a zero initializer, and may not be marked '<a
href="#globalvars"><tt>constant</tt></a>'. Functions and aliases may not
have common linkage.</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 object file 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_linkonce_odr">linkonce_odr</a></b></tt></dt>
<dt><tt><b><a name="linkage_weak_odr">weak_odr</a></b></tt></dt>
<dd>Some languages allow differing globals to be merged, such as two functions
with different semantics. Other languages, such as <tt>C++</tt>, ensure
that only equivalent globals are ever merged (the "one definition rule"
— "ODR"). Such languages can use the <tt>linkonce_odr</tt>
and <tt>weak_odr</tt> linkage types to indicate that the global will only
be merged with equivalent globals. These linkage types are otherwise the
same as their non-<tt>odr</tt> versions.</dd>
<dt><tt><b><a name="linkage_linkonce_odr_auto_hide">linkonce_odr_auto_hide</a></b></tt></dt>
<dd>Similar to "<tt>linkonce_odr</tt>", but nothing in the translation unit
takes the address of this definition. For instance, functions that had an
inline definition, but the compiler decided not to inline it.
<tt>linkonce_odr_auto_hide</tt> may have only <tt>default</tt> visibility.
The symbols are removed by the linker from the final linked image
(executable or dynamic library).</dd>
<dt><tt><b><a name="linkage_external">external</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 (Dynamic Link Libraries).</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>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 <tt>external</tt>, <tt>dllimport</tt>
or <tt>extern_weak</tt>.</p>
<p>Aliases can have only <tt>external</tt>, <tt>internal</tt>, <tt>weak</tt>
or <tt>weak_odr</tt> linkages.</p>
</div>
<!-- ======================================================================= -->
<h3>
<a name="callingconv">Calling Conventions</a>
</h3>
<div>
<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
(Application Binary Interface).
<a href="CodeGenerator.html#tailcallopt">Tail calls can only be optimized
when this or the GHC convention is used.</a> 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 <em>10</em></tt>" - GHC convention</b>:</dt>
<dd>This calling convention has been implemented specifically for use by the
<a href="http://www.haskell.org/ghc">Glasgow Haskell Compiler (GHC)</a>.
It passes everything in registers, going to extremes to achieve this by
disabling callee save registers. This calling convention should not be
used lightly but only for specific situations such as an alternative to
the <em>register pinning</em> performance technique often used when
implementing functional programming languages.At the moment only X86
supports this convention and it has the following limitations:
<ul>
<li>On <em>X86-32</em> only supports up to 4 bit type parameters. No
floating point types are supported.</li>
<li>On <em>X86-64</em> only supports up to 10 bit type parameters and
6 floating point parameters.</li>
</ul>
This calling convention supports
<a href="CodeGenerator.html#tailcallopt">tail call optimization</a> but
requires both the caller and callee are using it.
</dd>
<dt><b>"<tt>cc <<em>n</em>></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>
<!-- ======================================================================= -->
<h3>
<a name="visibility">Visibility Styles</a>
</h3>
<div>
<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 targets that use the ELF object file format, 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>
<!-- ======================================================================= -->
<h3>
<a name="namedtypes">Named Types</a>
</h3>
<div>
<p>LLVM IR allows you to specify name aliases for certain types. This can make
it easier to read the IR and make the IR more condensed (particularly when
recursive types are involved). An example of a name specification is:</p>
<pre class="doc_code">
%mytype = type { %mytype*, i32 }
</pre>
<p>You may give a name to any <a href="#typesystem">type</a> except
"<a href="#t_void">void</a>". Type name aliases may be used anywhere a type
is expected with the syntax "%mytype".</p>
<p>Note that type names are aliases for the structural type that they indicate,
and that you can therefore specify multiple names for the same type. This
often leads to confusing behavior when dumping out a .ll file. Since LLVM IR
uses structural typing, the name is not part of the type. When printing out
LLVM IR, the printer will pick <em>one name</em> to render all types of a
particular shape. This means that if you have code where two different
source types end up having the same LLVM type, that the dumper will sometimes
print the "wrong" or unexpected type. This is an important design point and
isn't going to change.</p>
</div>
<!-- ======================================================================= -->
<h3>
<a name="globalvars">Global Variables</a>
</h3>
<div>
<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.</p>
<p>A variable may be defined as <tt>thread_local</tt>, which
means that it will not be shared by threads (each thread will have a
separated copy of the variable). Not all targets support thread-local
variables. Optionally, a TLS model may be specified:</p>
<dl>
<dt><b><tt>localdynamic</tt></b>:</dt>
<dd>For variables that are only used within the current shared library.</dd>
<dt><b><tt>initialexec</tt></b>:</dt>
<dd>For variables in modules that will not be loaded dynamically.</dd>
<dt><b><tt>localexec</tt></b>:</dt>
<dd>For variables defined in the executable and only used within it.</dd>
</dl>
<p>The models correspond to the ELF TLS models; see
<a href="http://people.redhat.com/drepper/tls.pdf">ELF
Handling For Thread-Local Storage</a> for more information on under which
circumstances the different models may be used. The target may choose a
different TLS model if the specified model is not supported, or if a better
choice of model can be made.</p>
<p>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>Global variables can be marked with <tt>unnamed_addr</tt> which indicates
that the address is not significant, only the content. Constants marked
like this can be merged with other constants if they have the same
initializer. Note that a constant with significant address <em>can</em>
be merged with a <tt>unnamed_addr</tt> constant, the result being a
constant whose address is significant.</p>
<p>A global variable may be declared to reside in a target-specific numbered
address space. For targets that support them, address spaces may affect how
optimizations are performed and/or what target instructions are used to
access the variable. The default address space is zero. The address space
qualifier must precede any other attributes.</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, which must be a power
of 2. 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 exactly that
alignment. Targets and optimizers are not allowed to over-align the global
if the global has an assigned section. In this case, the extra alignment
could be observable: for example, code could assume that the globals are
densely packed in their section and try to iterate over them as an array,
alignment padding would break this iteration.</p>
<p>For example, the following defines a global in a numbered address space with
an initializer, section, and alignment:</p>
<pre class="doc_code">
@G = addrspace(5) constant float 1.0, section "foo", align 4
</pre>
<p>The following example defines a thread-local global with
the <tt>initialexec</tt> TLS model:</p>
<pre class="doc_code">
@G = thread_local(initialexec) global i32 0, align 4
</pre>
</div>
<!-- ======================================================================= -->
<h3>
<a name="functionstructure">Functions</a>
</h3>
<div>
<p>LLVM function definitions consist of the "<tt>define</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>,
an optional <tt>unnamed_addr</tt> attribute, 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>), optional
<a href="#fnattrs">function attributes</a>, an optional section, an optional
alignment, an optional <a href="#gc">garbage collector name</a>, an opening
curly brace, a list of basic blocks, and a closing curly brace.</p>
<p>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>,
an optional <tt>unnamed_addr</tt> attribute, a return type, an optional
<a href="#paramattrs">parameter attribute</a> for the return type, a function
name, a possibly empty list of arguments, an optional alignment, and an
optional <a href="#gc">garbage collector name</a>.</p>
<p>A function definition contains a list of basic blocks, forming the CFG
(Control Flow Graph) 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>
<p>If the <tt>unnamed_addr</tt> attribute is given, the address is know to not
be significant and two identical functions can be merged.</p>
<h5>Syntax:</h5>
<pre class="doc_code">
define [<a href="#linkage">linkage</a>] [<a href="#visibility">visibility</a>]
[<a href="#callingconv">cconv</a>] [<a href="#paramattrs">ret attrs</a>]
<ResultType> @<FunctionName> ([argument list])
[<a href="#fnattrs">fn Attrs</a>] [section "name"] [align N]
[<a href="#gc">gc</a>] { ... }
</pre>
</div>
<!-- ======================================================================= -->
<h3>
<a name="aliasstructure">Aliases</a>
</h3>
<div>
<p>Aliases act as "second name" for the aliasee value (which can be either
function, global variable, another alias 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>
<pre class="doc_code">
@<Name> = alias [Linkage] [Visibility] <AliaseeTy> @<Aliasee>
</pre>
</div>
<!-- ======================================================================= -->
<h3>
<a name="namedmetadatastructure">Named Metadata</a>
</h3>
<div>
<p>Named metadata is a collection of metadata. <a href="#metadata">Metadata
nodes</a> (but not metadata strings) are the only valid operands for
a named metadata.</p>
<h5>Syntax:</h5>
<pre class="doc_code">
; Some unnamed metadata nodes, which are referenced by the named metadata.
!0 = metadata !{metadata !"zero"}
!1 = metadata !{metadata !"one"}
!2 = metadata !{metadata !"two"}
; A named metadata.
!name = !{!0, !1, !2}
</pre>
</div>
<!-- ======================================================================= -->
<h3>
<a name="paramattrs">Parameter Attributes</a>
</h3>
<div>
<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,
not of the function type, so functions with different parameter attributes
can have the same function type.</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>
<pre class="doc_code">
declare i32 @printf(i8* noalias nocapture, ...)
declare i32 @atoi(i8 zeroext)
declare signext i8 @returns_signed_char()
</pre>
<p>Note that any attributes for the function result (<tt>nounwind</tt>,
<tt>readonly</tt>) come immediately after the argument list.</p>
<p>Currently, only the following parameter attributes are defined:</p>
<dl>
<dt><tt><b>zeroext</b></tt></dt>
<dd>This indicates to the code generator that the parameter or return value
should be zero-extended to the extent required by the target's ABI (which
is usually 32-bits, but is 8-bits for a i1 on x86-64) by the caller (for a
parameter) or the callee (for a return value).</dd>
<dt><tt><b>signext</b></tt></dt>
<dd>This indicates to the code generator that the parameter or return value
should be sign-extended to the extent required by the target's ABI (which
is usually 32-bits) by the caller (for a parameter) or the callee (for a
return value).</dd>
<dt><tt><b>inreg</b></tt></dt>
<dd>This indicates that this parameter or return value should be treated in a
special target-dependent fashion during while emitting code for a function
call or return (usually, by putting it in a register as opposed to memory,
though some targets use it to distinguish between two different kinds of
registers). Use of this attribute is target-specific.</dd>
<dt><tt><b><a name="byval">byval</a></b></tt></dt>
<dd><p>This indicates that the pointer parameter should really be passed by
value to the function. The attribute implies that a hidden copy of the
pointee
is made between the caller and the callee, so the callee is unable to
modify the value in the caller. This attribute is only valid on LLVM
pointer arguments. It is generally used to pass structs and arrays by
value, but is also valid on pointers to scalars. The copy is considered
to belong to the caller not the callee (for example,
<tt><a href="#readonly">readonly</a></tt> functions should not write to
<tt>byval</tt> parameters). This is not a valid attribute for return
values.</p>
<p>The byval attribute also supports specifying an alignment with
the align attribute. It indicates the alignment of the stack slot to
form and the known alignment of the pointer specified to the call site. If
the alignment is not specified, then the code generator makes a
target-specific assumption.</p></dd>
<dt><tt><b><a name="sret">sret</a></b></tt></dt>
<dd>This indicates that the pointer parameter specifies the address of a
structure that is the return value of the function in the source program.
This pointer must be guaranteed by the caller to be valid: loads and
stores to the structure may be assumed by the callee to not to trap. This
may only be applied to the first parameter. This is not a valid attribute
for return values. </dd>
<dt><tt><b><a name="noalias">noalias</a></b></tt></dt>
<dd>This indicates that pointer values
<a href="#pointeraliasing"><i>based</i></a> on the argument or return
value do not alias pointer values which are not <i>based</i> on it,
ignoring certain "irrelevant" dependencies.
For a call to the parent function, dependencies between memory
references from before or after the call and from those during the call
are "irrelevant" to the <tt>noalias</tt> keyword for the arguments and
return value used in that call.
The caller shares the responsibility with the callee for ensuring that
these requirements are met.
For further details, please see the discussion of the NoAlias response in
<a href="AliasAnalysis.html#MustMayNo">alias analysis</a>.<br>
<br>
Note that this definition of <tt>noalias</tt> is intentionally
similar to the definition of <tt>restrict</tt> in C99 for function
arguments, though it is slightly weaker.
<br>
For function return values, C99's <tt>restrict</tt> is not meaningful,
while LLVM's <tt>noalias</tt> is.
</dd>
<dt><tt><b><a name="nocapture">nocapture</a></b></tt></dt>
<dd>This indicates that the callee does not make any copies of the pointer
that outlive the callee itself. This is not a valid attribute for return
values.</dd>
<dt><tt><b><a name="nest">nest</a></b></tt></dt>
<dd>This indicates that the pointer parameter can be excised using the
<a href="#int_trampoline">trampoline intrinsics</a>. This is not a valid
attribute for return values.</dd>
</dl>
</div>
<!-- ======================================================================= -->
<h3>
<a name="gc">Garbage Collector Names</a>
</h3>
<div>
<p>Each function may specify a garbage collector name, which is simply a
string:</p>
<pre class="doc_code">
define void @f() gc "name" { ... }
</pre>
<p>The compiler declares the supported values of <i>name</i>. Specifying a
collector which will cause the compiler to alter its output in order to
support the named garbage collection algorithm.</p>
</div>
<!-- ======================================================================= -->
<h3>
<a name="fnattrs">Function Attributes</a>
</h3>
<div>
<p>Function attributes are set to communicate additional information about a
function. Function attributes are considered to be part of the function, not
of the function type, so functions with different parameter attributes can
have the same function type.</p>
<p>Function attributes are simple keywords that follow the type specified. If
multiple attributes are needed, they are space separated. For example:</p>
<pre class="doc_code">
define void @f() noinline { ... }
define void @f() alwaysinline { ... }
define void @f() alwaysinline optsize { ... }
define void @f() optsize { ... }
</pre>
<dl>
<dt><tt><b>address_safety</b></tt></dt>
<dd>This attribute indicates that the address safety analysis
is enabled for this function. </dd>
<dt><tt><b>alignstack(<<em>n</em>>)</b></tt></dt>
<dd>This attribute indicates that, when emitting the prologue and epilogue,
the backend should forcibly align the stack pointer. Specify the
desired alignment, which must be a power of two, in parentheses.
<dt><tt><b>alwaysinline</b></tt></dt>
<dd>This attribute indicates that the inliner should attempt to inline this
function into callers whenever possible, ignoring any active inlining size
threshold for this caller.</dd>
<dt><tt><b>nonlazybind</b></tt></dt>
<dd>This attribute suppresses lazy symbol binding for the function. This
may make calls to the function faster, at the cost of extra program
startup time if the function is not called during program startup.</dd>
<dt><tt><b>inlinehint</b></tt></dt>
<dd>This attribute indicates that the source code contained a hint that inlining
this function is desirable (such as the "inline" keyword in C/C++). It
is just a hint; it imposes no requirements on the inliner.</dd>
<dt><tt><b>naked</b></tt></dt>
<dd>This attribute disables prologue / epilogue emission for the function.
This can have very system-specific consequences.</dd>
<dt><tt><b>noimplicitfloat</b></tt></dt>
<dd>This attributes disables implicit floating point instructions.</dd>
<dt><tt><b>noinline</b></tt></dt>
<dd>This attribute indicates that the inliner should never inline this
function in any situation. This attribute may not be used together with
the <tt>alwaysinline</tt> attribute.</dd>
<dt><tt><b>noredzone</b></tt></dt>
<dd>This attribute indicates that the code generator should not use a red
zone, even if the target-specific ABI normally permits it.</dd>
<dt><tt><b>noreturn</b></tt></dt>
<dd>This function attribute indicates that the function never returns
normally. This produces undefined behavior at runtime if the function
ever does dynamically return.</dd>
<dt><tt><b>nounwind</b></tt></dt>
<dd>This function attribute indicates that the function never returns with an
unwind or exceptional control flow. If the function does unwind, its
runtime behavior is undefined.</dd>
<dt><tt><b>optsize</b></tt></dt>
<dd>This attribute suggests that optimization passes and code generator passes
make choices that keep the code size of this function low, and otherwise
do optimizations specifically to reduce code size.</dd>
<dt><tt><b>readnone</b></tt></dt>
<dd>This attribute indicates that the function computes its result (or decides
to unwind an exception) based strictly on its arguments, without
dereferencing any pointer arguments or otherwise accessing any mutable
state (e.g. memory, control registers, etc) visible to caller functions.
It does not write through any pointer arguments
(including <tt><a href="#byval">byval</a></tt> arguments) and never
changes any state visible to callers. This means that it cannot unwind
exceptions by calling the <tt>C++</tt> exception throwing methods.</dd>
<dt><tt><b><a name="readonly">readonly</a></b></tt></dt>
<dd>This attribute indicates that the function does not write through any
pointer arguments (including <tt><a href="#byval">byval</a></tt>
arguments) or otherwise modify any state (e.g. memory, control registers,
etc) visible to caller functions. It may dereference pointer arguments
and read state that may be set in the caller. A readonly function always
returns the same value (or unwinds an exception identically) when called
with the same set of arguments and global state. It cannot unwind an
exception by calling the <tt>C++</tt> exception throwing methods.</dd>
<dt><tt><b><a name="returns_twice">returns_twice</a></b></tt></dt>
<dd>This attribute indicates that this function can return twice. The
C <code>setjmp</code> is an example of such a function. The compiler
disables some optimizations (like tail calls) in the caller of these
functions.</dd>
<dt><tt><b><a name="ssp">ssp</a></b></tt></dt>
<dd>This attribute indicates that the function should emit a stack smashing
protector. It is in the form of a "canary"—a random value placed on
the stack before the local variables that's checked upon return from the
function to see if it has been overwritten. A heuristic is used to
determine if a function needs stack protectors or not.<br>
<br>
If a function that has an <tt>ssp</tt> attribute is inlined into a
function that doesn't have an <tt>ssp</tt> attribute, then the resulting
function will have an <tt>ssp</tt> attribute.</dd>
<dt><tt><b>sspreq</b></tt></dt>
<dd>This attribute indicates that the function should <em>always</em> emit a
stack smashing protector. This overrides
the <tt><a href="#ssp">ssp</a></tt> function attribute.<br>
<br>
If a function that has an <tt>sspreq</tt> attribute is inlined into a
function that doesn't have an <tt>sspreq</tt> attribute or which has
an <tt>ssp</tt> attribute, then the resulting function will have
an <tt>sspreq</tt> attribute.</dd>
<dt><tt><b><a name="uwtable">uwtable</a></b></tt></dt>
<dd>This attribute indicates that the ABI being targeted requires that
an unwind table entry be produce for this function even if we can
show that no exceptions passes by it. This is normally the case for
the ELF x86-64 abi, but it can be disabled for some compilation
units.</dd>
</dl>
</div>
<!-- ======================================================================= -->
<h3>
<a name="moduleasm">Module-Level Inline Assembly</a>
</h3>
<div>
<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 <tt>.ll</tt> file if desired. The syntax is very simple:</p>
<pre class="doc_code">
module asm "inline asm code goes here"
module asm "more can go here"
</pre>
<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>
<!-- ======================================================================= -->
<h3>
<a name="datalayout">Data Layout</a>
</h3>
<div>
<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 class="doc_code">
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 the target lays out data in little-endian form. That is,
the bits with the least significance have the lowest address
location.</dd>
<dt><tt>S<i>size</i></tt></dt>
<dd>Specifies the natural alignment of the stack in bits. Alignment promotion
of stack variables is limited to the natural stack alignment to avoid
dynamic stack realignment. The stack alignment must be a multiple of
8-bits. If omitted, the natural stack alignment defaults to "unspecified",
which does not prevent any alignment promotions.</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>. Only values of <i>size</i> that are supported by the target
will work. 32 (float) and 64 (double) are supported on all targets;
80 or 128 (different flavors of long double) are also supported on some
targets.
<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>
<dt><tt>s<i>size</i>:<i>abi</i>:<i>pref</i></tt></dt>
<dd>This specifies the alignment for a stack object of a given bit
<i>size</i>.</dd>
<dt><tt>n<i>size1</i>:<i>size2</i>:<i>size3</i>...</tt></dt>
<dd>This specifies a set of native integer widths for the target CPU
in bits. For example, it might contain "n32" for 32-bit PowerPC,
"n32:64" for PowerPC 64, or "n8:16:32:64" for X86-64. Elements of
this set are considered to support most general arithmetic
operations efficiently.</dd>
</dl>
<p>When constructing the data layout for a given target, LLVM starts with a
default set of specifications which are then (possibly) overridden 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:64:64:64</tt> - 64-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>
<li><tt>s0:64:64</tt> - stack objects are 64-bit aligned</li>
</ul>
<p>When LLVM is determining the alignment for a given type, it uses the
following rules:</p>
<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 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>
<p>The function of the data layout string may not be what you expect. Notably,
this is not a specification from the frontend of what alignment the code
generator should use.</p>
<p>Instead, if specified, the target data layout is required to match what the
ultimate <em>code generator</em> expects. This string is used by the
mid-level optimizers to
improve code, and this only works if it matches what the ultimate code
generator uses. If you would like to generate IR that does not embed this
target-specific detail into the IR, then you don't have to specify the
string. This will disable some optimizations that require precise layout
information, but this also prevents those optimizations from introducing
target specificity into the IR.</p>
</div>
<!-- ======================================================================= -->
<h3>
<a name="pointeraliasing">Pointer Aliasing Rules</a>
</h3>
<div>
<p>Any memory access must be done through a pointer value associated
with an address range of the memory access, otherwise the behavior
is undefined. Pointer values are associated with address ranges
according to the following rules:</p>
<ul>
<li>A pointer value is associated with the addresses associated with
any value it is <i>based</i> on.
<li>An address of a global variable is associated with the address
range of the variable's storage.</li>
<li>The result value of an allocation instruction is associated with
the address range of the allocated storage.</li>
<li>A null pointer in the default address-space is associated with
no address.</li>
<li>An integer constant other than zero or a pointer value returned
from a function not defined within LLVM may be associated with address
ranges allocated through mechanisms other than those provided by
LLVM. Such ranges shall not overlap with any ranges of addresses
allocated by mechanisms provided by LLVM.</li>
</ul>
<p>A pointer value is <i>based</i> on another pointer value according
to the following rules:</p>
<ul>
<li>A pointer value formed from a
<tt><a href="#i_getelementptr">getelementptr</a></tt> operation
is <i>based</i> on the first operand of the <tt>getelementptr</tt>.</li>
<li>The result value of a
<tt><a href="#i_bitcast">bitcast</a></tt> is <i>based</i> on the operand
of the <tt>bitcast</tt>.</li>
<li>A pointer value formed by an
<tt><a href="#i_inttoptr">inttoptr</a></tt> is <i>based</i> on all
pointer values that contribute (directly or indirectly) to the
computation of the pointer's value.</li>
<li>The "<i>based</i> on" relationship is transitive.</li>
</ul>
<p>Note that this definition of <i>"based"</i> is intentionally
similar to the definition of <i>"based"</i> in C99, though it is
slightly weaker.</p>
<p>LLVM IR does not associate types with memory. The result type of a
<tt><a href="#i_load">load</a></tt> merely indicates the size and
alignment of the memory from which to load, as well as the
interpretation of the value. The first operand type of a
<tt><a href="#i_store">store</a></tt> similarly only indicates the size
and alignment of the store.</p>
<p>Consequently, type-based alias analysis, aka TBAA, aka
<tt>-fstrict-aliasing</tt>, is not applicable to general unadorned
LLVM IR. <a href="#metadata">Metadata</a> may be used to encode
additional information which specialized optimization passes may use
to implement type-based alias analysis.</p>
</div>
<!-- ======================================================================= -->
<h3>
<a name="volatile">Volatile Memory Accesses</a>
</h3>
<div>
<p>Certain memory accesses, such as <a href="#i_load"><tt>load</tt></a>s, <a
href="#i_store"><tt>store</tt></a>s, and <a
href="#int_memcpy"><tt>llvm.memcpy</tt></a>s may be marked <tt>volatile</tt>.
The optimizers must not change the number of volatile operations or change their
order of execution relative to other volatile operations. The optimizers
<i>may</i> change the order of volatile operations relative to non-volatile
operations. This is not Java's "volatile" and has no cross-thread
synchronization behavior.</p>
</div>
<!-- ======================================================================= -->
<h3>
<a name="memmodel">Memory Model for Concurrent Operations</a>
</h3>
<div>
<p>The LLVM IR does not define any way to start parallel threads of execution
or to register signal handlers. Nonetheless, there are platform-specific
ways to create them, and we define LLVM IR's behavior in their presence. This
model is inspired by the C++0x memory model.</p>
<p>For a more informal introduction to this model, see the
<a href="Atomics.html">LLVM Atomic Instructions and Concurrency Guide</a>.
<p>We define a <i>happens-before</i> partial order as the least partial order
that</p>
<ul>
<li>Is a superset of single-thread program order, and</li>
<li>When a <i>synchronizes-with</i> <tt>b</tt>, includes an edge from
<tt>a</tt> to <tt>b</tt>. <i>Synchronizes-with</i> pairs are introduced
by platform-specific techniques, like pthread locks, thread
creation, thread joining, etc., and by atomic instructions.
(See also <a href="#ordering">Atomic Memory Ordering Constraints</a>).
</li>
</ul>
<p>Note that program order does not introduce <i>happens-before</i> edges
between a thread and signals executing inside that thread.</p>
<p>Every (defined) read operation (load instructions, memcpy, atomic
loads/read-modify-writes, etc.) <var>R</var> reads a series of bytes written by
(defined) write operations (store instructions, atomic
stores/read-modify-writes, memcpy, etc.). For the purposes of this section,
initialized globals are considered to have a write of the initializer which is
atomic and happens before any other read or write of the memory in question.
For each byte of a read <var>R</var>, <var>R<sub>byte</sub></var> may see
any write to the same byte, except:</p>
<ul>
<li>If <var>write<sub>1</sub></var> happens before
<var>write<sub>2</sub></var>, and <var>write<sub>2</sub></var> happens
before <var>R<sub>byte</sub></var>, then <var>R<sub>byte</sub></var>
does not see <var>write<sub>1</sub></var>.
<li>If <var>R<sub>byte</sub></var> happens before
<var>write<sub>3</sub></var>, then <var>R<sub>byte</sub></var> does not
see <var>write<sub>3</sub></var>.
</ul>
<p>Given that definition, <var>R<sub>byte</sub></var> is defined as follows:
<ul>
<li>If <var>R</var> is volatile, the result is target-dependent. (Volatile
is supposed to give guarantees which can support
<code>sig_atomic_t</code> in C/C++, and may be used for accesses to
addresses which do not behave like normal memory. It does not generally
provide cross-thread synchronization.)
<li>Otherwise, if there is no write to the same byte that happens before
<var>R<sub>byte</sub></var>, <var>R<sub>byte</sub></var> returns
<tt>undef</tt> for that byte.
<li>Otherwise, if <var>R<sub>byte</sub></var> may see exactly one write,
<var>R<sub>byte</sub></var> returns the value written by that
write.</li>
<li>Otherwise, if <var>R</var> is atomic, and all the writes
<var>R<sub>byte</sub></var> may see are atomic, it chooses one of the
values written. See the <a href="#ordering">Atomic Memory Ordering
Constraints</a> section for additional constraints on how the choice
is made.
<li>Otherwise <var>R<sub>byte</sub></var> returns <tt>undef</tt>.</li>
</ul>
<p><var>R</var> returns the value composed of the series of bytes it read.
This implies that some bytes within the value may be <tt>undef</tt>
<b>without</b> the entire value being <tt>undef</tt>. Note that this only
defines the semantics of the operation; it doesn't mean that targets will
emit more than one instruction to read the series of bytes.</p>
<p>Note that in cases where none of the atomic intrinsics are used, this model
places only one restriction on IR transformations on top of what is required
for single-threaded execution: introducing a store to a byte which might not
otherwise be stored is not allowed in general. (Specifically, in the case
where another thread might write to and read from an address, introducing a
store can change a load that may see exactly one write into a load that may
see multiple writes.)</p>
<!-- FIXME: This model assumes all targets where concurrency is relevant have
a byte-size store which doesn't affect adjacent bytes. As far as I can tell,
none of the backends currently in the tree fall into this category; however,
there might be targets which care. If there are, we want a paragraph
like the following:
Targets may specify that stores narrower than a certain width are not
available; on such a target, for the purposes of this model, treat any
non-atomic write with an alignment or width less than the minimum width
as if it writes to the relevant surrounding bytes.
-->
</div>
<!-- ======================================================================= -->
<h3>
<a name="ordering">Atomic Memory Ordering Constraints</a>
</h3>
<div>
<p>Atomic instructions (<a href="#i_cmpxchg"><code>cmpxchg</code></a>,
<a href="#i_atomicrmw"><code>atomicrmw</code></a>,
<a href="#i_fence"><code>fence</code></a>,
<a href="#i_load"><code>atomic load</code></a>, and
<a href="#i_store"><code>atomic store</code></a>) take an ordering parameter
that determines which other atomic instructions on the same address they
<i>synchronize with</i>. These semantics are borrowed from Java and C++0x,
but are somewhat more colloquial. If these descriptions aren't precise enough,
check those specs (see spec references in the
<a href="Atomics.html#introduction">atomics guide</a>).
<a href="#i_fence"><code>fence</code></a> instructions
treat these orderings somewhat differently since they don't take an address.
See that instruction's documentation for details.</p>
<p>For a simpler introduction to the ordering constraints, see the
<a href="Atomics.html">LLVM Atomic Instructions and Concurrency Guide</a>.</p>
<dl>
<dt><code>unordered</code></dt>
<dd>The set of values that can be read is governed by the happens-before
partial order. A value cannot be read unless some operation wrote it.
This is intended to provide a guarantee strong enough to model Java's
non-volatile shared variables. This ordering cannot be specified for
read-modify-write operations; it is not strong enough to make them atomic
in any interesting way.</dd>
<dt><code>monotonic</code></dt>
<dd>In addition to the guarantees of <code>unordered</code>, there is a single
total order for modifications by <code>monotonic</code> operations on each
address. All modification orders must be compatible with the happens-before
order. There is no guarantee that the modification orders can be combined to
a global total order for the whole program (and this often will not be
possible). The read in an atomic read-modify-write operation
(<a href="#i_cmpxchg"><code>cmpxchg</code></a> and
<a href="#i_atomicrmw"><code>atomicrmw</code></a>)
reads the value in the modification order immediately before the value it
writes. If one atomic read happens before another atomic read of the same
address, the later read must see the same value or a later value in the
address's modification order. This disallows reordering of
<code>monotonic</code> (or stronger) operations on the same address. If an
address is written <code>monotonic</code>ally by one thread, and other threads
<code>monotonic</code>ally read that address repeatedly, the other threads must
eventually see the write. This corresponds to the C++0x/C1x
<code>memory_order_relaxed</code>.</dd>
<dt><code>acquire</code></dt>
<dd>In addition to the guarantees of <code>monotonic</code>,
a <i>synchronizes-with</i> edge may be formed with a <code>release</code>
operation. This is intended to model C++'s <code>memory_order_acquire</code>.</dd>
<dt><code>release</code></dt>
<dd>In addition to the guarantees of <code>monotonic</code>, if this operation
writes a value which is subsequently read by an <code>acquire</code> operation,
it <i>synchronizes-with</i> that operation. (This isn't a complete
description; see the C++0x definition of a release sequence.) This corresponds
to the C++0x/C1x <code>memory_order_release</code>.</dd>
<dt><code>acq_rel</code> (acquire+release)</dt><dd>Acts as both an
<code>acquire</code> and <code>release</code> operation on its address.
This corresponds to the C++0x/C1x <code>memory_order_acq_rel</code>.</dd>
<dt><code>seq_cst</code> (sequentially consistent)</dt><dd>
<dd>In addition to the guarantees of <code>acq_rel</code>
(<code>acquire</code> for an operation which only reads, <code>release</code>
for an operation which only writes), there is a global total order on all
sequentially-consistent operations on all addresses, which is consistent with
the <i>happens-before</i> partial order and with the modification orders of
all the affected addresses. Each sequentially-consistent read sees the last
preceding write to the same address in this global order. This corresponds
to the C++0x/C1x <code>memory_order_seq_cst</code> and Java volatile.</dd>
</dl>
<p id="singlethread">If an atomic operation is marked <code>singlethread</code>,
it only <i>synchronizes with</i> or participates in modification and seq_cst
total orderings with other operations running in the same thread (for example,
in signal handlers).</p>
</div>
</div>
<!-- *********************************************************************** -->
<h2><a name="typesystem">Type System</a></h2>
<!-- *********************************************************************** -->
<div>
<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 intermediate representation 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>
<!-- ======================================================================= -->
<h3>
<a name="t_classifications">Type Classifications</a>
</h3>
<div>
<p>The 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 href="#t_integer">integer</a></td>
<td><tt>i1, i2, i3, ... i8, ... i16, ... i32, ... i64, ... </tt></td>
</tr>
<tr>
<td><a href="#t_floating">floating point</a></td>
<td><tt>half, float, double, x86_fp80, fp128, ppc_fp128</tt></td>
</tr>
<tr>
<td><a name="t_firstclass">first class</a></td>
<td><a href="#t_integer">integer</a>,
<a href="#t_floating">floating point</a>,
<a href="#t_pointer">pointer</a>,
<a href="#t_vector">vector</a>,
<a href="#t_struct">structure</a>,
<a href="#t_array">array</a>,
<a href="#t_label">label</a>,
<a href="#t_metadata">metadata</a>.
</td>
</tr>
<tr>
<td><a href="#t_primitive">primitive</a></td>
<td><a href="#t_label">label</a>,
<a href="#t_void">void</a>,
<a href="#t_integer">integer</a>,
<a href="#t_floating">floating point</a>,
<a href="#t_x86mmx">x86mmx</a>,
<a href="#t_metadata">metadata</a>.</td>
</tr>
<tr>
<td><a href="#t_derived">derived</a></td>
<td><a href="#t_array">array</a>,
<a href="#t_function">function</a>,
<a href="#t_pointer">pointer</a>,
<a href="#t_struct">structure</a>,
<a href="#t_vector">vector</a>,
<a href="#t_opaque">opaque</a>.
</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.</p>
</div>
<!-- ======================================================================= -->
<h3>
<a name="t_primitive">Primitive Types</a>
</h3>
<div>
<p>The primitive types are the fundamental building blocks of the LLVM
system.</p>
<!-- _______________________________________________________________________ -->
<h4>
<a name="t_integer">Integer Type</a>
</h4>
<div>
<h5>Overview:</h5>
<p>The integer type is a very simple type that simply specifies an arbitrary
bit width for the integer type desired. Any bit width from 1 bit to
2<sup>23</sup>-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></td>
<td class="left">a single-bit integer.</td>
</tr>
<tr class="layout">
<td class="left"><tt>i32</tt></td>
<td class="left">a 32-bit integer.</td>
</tr>
<tr class="layout">
<td class="left"><tt>i1942652</tt></td>
<td class="left">a really big integer of over 1 million bits.</td>
</tr>
</table>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="t_floating">Floating Point Types</a>
</h4>
<div>
<table>
<tbody>
<tr><th>Type</th><th>Description</th></tr>
<tr><td><tt>half</tt></td><td>16-bit floating point value</td></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>
<tr><td><tt>fp128</tt></td><td>128-bit floating point value (112-bit mantissa)</td></tr>
<tr><td><tt>x86_fp80</tt></td><td>80-bit floating point value (X87)</td></tr>
<tr><td><tt>ppc_fp128</tt></td><td>128-bit floating point value (two 64-bits)</td></tr>
</tbody>
</table>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="t_x86mmx">X86mmx Type</a>
</h4>
<div>
<h5>Overview:</h5>
<p>The x86mmx type represents a value held in an MMX register on an x86 machine. The operations allowed on it are quite limited: parameters and return values, load and store, and bitcast. User-specified MMX instructions are represented as intrinsic or asm calls with arguments and/or results of this type. There are no arrays, vectors or constants of this type.</p>
<h5>Syntax:</h5>
<pre>
x86mmx
</pre>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="t_void">Void Type</a>
</h4>
<div>
<h5>Overview:</h5>
<p>The void type does not represent any value and has no size.</p>
<h5>Syntax:</h5>
<pre>
void
</pre>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="t_label">Label Type</a>
</h4>
<div>
<h5>Overview:</h5>
<p>The label type represents code labels.</p>
<h5>Syntax:</h5>
<pre>
label
</pre>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="t_metadata">Metadata Type</a>
</h4>
<div>
<h5>Overview:</h5>
<p>The metadata type represents embedded metadata. No derived types may be
created from metadata except for <a href="#t_function">function</a>
arguments.
<h5>Syntax:</h5>
<pre>
metadata
</pre>
</div>
</div>
<!-- ======================================================================= -->
<h3>
<a name="t_derived">Derived Types</a>
</h3>
<div>
<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. Each of these types contain one or more element types which
may be a primitive type, or another derived type. For example, it is
possible to have a two dimensional array, using an array as the element type
of another array.</p>
<!-- _______________________________________________________________________ -->
<h4>
<a name="t_aggregate">Aggregate Types</a>
</h4>
<div>
<p>Aggregate Types are a subset of derived types that can contain multiple
member types. <a href="#t_array">Arrays</a> and
<a href="#t_struct">structs</a> are aggregate types.
<a href="#t_vector">Vectors</a> are not considered to be aggregate types.</p>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="t_array">Array Type</a>
</h4>
<div>
<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>
[<# elements> x <elementtype>]
</pre>
<p>The number of elements is a constant integer value; <tt>elementtype</tt> 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></td>
<td class="left">Array of 40 32-bit integer values.</td>
</tr>
<tr class="layout">
<td class="left"><tt>[41 x i32]</tt></td>
<td class="left">Array of 41 32-bit integer values.</td>
</tr>
<tr class="layout">
<td class="left"><tt>[4 x i8]</tt></td>
<td class="left">Array of 4 8-bit integer values.</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></td>
<td class="left">3x4 array of 32-bit integer values.</td>
</tr>
<tr class="layout">
<td class="left"><tt>[12 x [10 x float]]</tt></td>
<td class="left">12x10 array of single precision floating point values.</td>
</tr>
<tr class="layout">
<td class="left"><tt>[2 x [3 x [4 x i16]]]</tt></td>
<td class="left">2x3x4 array of 16-bit integer values.</td>
</tr>
</table>
<p>There is no restriction on indexing beyond the end of the array implied by
a static type (though there are restrictions on indexing beyond the bounds
of an allocated object in some cases). This means that single-dimension
'variable sized array' addressing can be implemented in LLVM with a zero
length array type. An implementation of 'pascal style arrays' in LLVM could
use the type "<tt>{ i32, [0 x float]}</tt>", for example.</p>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="t_function">Function Type</a>
</h4>
<div>
<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. The return type of a
function type is a first class type or a void type.</p>
<h5>Syntax:</h5>
<pre>
<returntype> (<parameter list>)
</pre>
<p>...where '<tt><parameter list></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. '<tt><returntype></tt>' is any type except
<a href="#t_label">label</a>.</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 (i16, i32 *) *
</tt></td>
<td class="left"><a href="#t_pointer">Pointer</a> to a function that takes
an <tt>i16</tt> 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><tr class="layout">
<td class="left"><tt>{i32, i32} (i32)</tt></td>
<td class="left">A function taking an <tt>i32</tt>, returning a
<a href="#t_struct">structure</a> containing two <tt>i32</tt> values
</td>
</tr>
</table>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="t_struct">Structure Type</a>
</h4>
<div>
<h5>Overview:</h5>
<p>The structure type is used to represent a collection of data members together
in memory. The elements of a structure may be any type that has a size.</p>
<p>Structures in memory 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.
Structures in registers are accessed using the
'<tt><a href="#i_extractvalue">extractvalue</a></tt>' and
'<tt><a href="#i_insertvalue">insertvalue</a></tt>' instructions.</p>
<p>Structures may optionally be "packed" structures, which indicate that the
alignment of the struct is one byte, and that there is no padding between
the elements. In non-packed structs, padding between field types is inserted
as defined by the TargetData string in the module, which is required to match
what the underlying code generator expects.</p>
<p>Structures can either be "literal" or "identified". A literal structure is
defined inline with other types (e.g. <tt>{i32, i32}*</tt>) whereas identified
types are always defined at the top level with a name. Literal types are
uniqued by their contents and can never be recursive or opaque since there is
no way to write one. Identified types can be recursive, can be opaqued, and are
never uniqued.
</p>
<h5>Syntax:</h5>
<pre>
%T1 = type { <type list> } <i>; Identified normal struct type</i>
%T2 = type <{ <type list> }> <i>; Identified packed struct type</i>
</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>{ float, i32 (i32) * }</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>
<tr class="layout">
<td class="left"><tt><{ i8, i32 }></tt></td>
<td class="left">A packed struct known to be 5 bytes in size.</td>
</tr>
</table>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="t_opaque">Opaque Structure Types</a>
</h4>
<div>
<h5>Overview:</h5>
<p>Opaque structure types are used to represent named structure types that do
not have a body specified. This corresponds (for example) to the C notion of
a forward declared structure.</p>
<h5>Syntax:</h5>
<pre>
%X = type opaque
%52 = type opaque
</pre>
<h5>Examples:</h5>
<table class="layout">
<tr class="layout">
<td class="left"><tt>opaque</tt></td>
<td class="left">An opaque type.</td>
</tr>
</table>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="t_pointer">Pointer Type</a>
</h4>
<div>
<h5>Overview:</h5>
<p>The pointer type is used to specify memory locations.
Pointers are commonly used to reference objects in memory.</p>
<p>Pointer types may have an optional address space attribute defining the
numbered address space where the pointed-to object resides. The default
address space is number zero. The semantics of non-zero address
spaces are target-specific.</p>
<p>Note that LLVM does not permit pointers to void (<tt>void*</tt>) nor does it
permit pointers to labels (<tt>label*</tt>). Use <tt>i8*</tt> instead.</p>
<h5>Syntax:</h5>
<pre>
<type> *
</pre>
<h5>Examples:</h5>
<table class="layout">
<tr class="layout">
<td class="left"><tt>[4 x i32]*</tt></td>
<td class="left">A <a href="#t_pointer">pointer</a> to <a
href="#t_array">array</a> of four <tt>i32</tt> values.</td>
</tr>
<tr class="layout">
<td class="left"><tt>i32 (i32*) *</tt></td>
<td class="left"> 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>
<tr class="layout">
<td class="left"><tt>i32 addrspace(5)*</tt></td>
<td class="left">A <a href="#t_pointer">pointer</a> to an <tt>i32</tt> value
that resides in address space #5.</td>
</tr>
</table>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="t_vector">Vector Type</a>
</h4>
<div>
<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. Vector types are considered
<a href="#t_firstclass">first class</a>.</p>
<h5>Syntax:</h5>
<pre>
< <# elements> x <elementtype> >
</pre>
<p>The number of elements is a constant integer value larger than 0; elementtype
may be any integer or floating point type, or a pointer to these types.
Vectors of size zero are not allowed. </p>
<h5>Examples:</h5>
<table class="layout">
<tr class="layout">
<td class="left"><tt><4 x i32></tt></td>
<td class="left">Vector of 4 32-bit integer values.</td>
</tr>
<tr class="layout">
<td class="left"><tt><8 x float></tt></td>
<td class="left">Vector of 8 32-bit floating-point values.</td>
</tr>
<tr class="layout">
<td class="left"><tt><2 x i64></tt></td>
<td class="left">Vector of 2 64-bit integer values.</td>
</tr>
<tr class="layout">
<td class="left"><tt><4 x i64*></tt></td>
<td class="left">Vector of 4 pointers to 64-bit integer values.</td>
</tr>
</table>
</div>
</div>
</div>
<!-- *********************************************************************** -->
<h2><a name="constants">Constants</a></h2>
<!-- *********************************************************************** -->
<div>
<p>LLVM has several different basic types of constants. This section describes
them all and their syntax.</p>
<!-- ======================================================================= -->
<h3>
<a name="simpleconstants">Simple Constants</a>
</h3>
<div>
<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_integer">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). The assembler requires the exact decimal value of a
floating-point constant. For example, the assembler accepts 1.25 but
rejects 1.3 because 1.3 is a repeating decimal in binary. 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 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 in a reasonable number of
digits. 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>
<p>When using the hexadecimal form, constants of types half, float, and double are
represented using the 16-digit form shown above (which matches the IEEE754
representation for double); half and float values must, however, be exactly
representable as IEE754 half and single precision, respectively.
Hexadecimal format is always used
for long double, and there are three forms of long double. The 80-bit format
used by x86 is represented as <tt>0xK</tt> followed by 20 hexadecimal digits.
The 128-bit format used by PowerPC (two adjacent doubles) is represented
by <tt>0xM</tt> followed by 32 hexadecimal digits. The IEEE 128-bit format
is represented by <tt>0xL</tt> followed by 32 hexadecimal digits; no
currently supported target uses this format. Long doubles will only work if
they match the long double format on your target. The IEEE 16-bit format
(half precision) is represented by <tt>0xH</tt> followed by 4 hexadecimal
digits. All hexadecimal formats are big-endian (sign bit at the left).</p>
<p>There are no constants of type x86mmx.</p>
</div>
<!-- ======================================================================= -->
<h3>
<a name="aggregateconstants"></a> <!-- old anchor -->
<a name="complexconstants">Complex Constants</a>
</h3>
<div>
<p>Complex constants are a (potentially recursive) combination of simple
constants and smaller complex 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><></tt>)). For example: "<tt>< i32
42, i32 11, i32 74, i32 100 ></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
<a href="#t_aggregate">aggregate</a> 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>
<dt><b>Metadata node</b></dt>
<dd>A metadata node is a structure-like constant with
<a href="#t_metadata">metadata type</a>. For example: "<tt>metadata !{
i32 0, metadata !"test" }</tt>". Unlike other constants that are meant to
be interpreted as part of the instruction stream, metadata is a place to
attach additional information such as debug info.</dd>
</dl>
</div>
<!-- ======================================================================= -->
<h3>
<a name="globalconstants">Global Variable and Function Addresses</a>
</h3>
<div>
<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>
<pre class="doc_code">
@X = global i32 17
@Y = global i32 42
@Z = global [2 x i32*] [ i32* @X, i32* @Y ]
</pre>
</div>
<!-- ======================================================================= -->
<h3>
<a name="undefvalues">Undefined Values</a>
</h3>
<div>
<p>The string '<tt>undef</tt>' can be used anywhere a constant is expected, and
indicates that the user of the value may receive an unspecified bit-pattern.
Undefined values may be of any type (other than '<tt>label</tt>'
or '<tt>void</tt>') and be used anywhere a constant is permitted.</p>
<p>Undefined values are useful because they indicate to the compiler that the
program is well defined no matter what value is used. This gives the
compiler more freedom to optimize. Here are some examples of (potentially
surprising) transformations that are valid (in pseudo IR):</p>
<pre class="doc_code">
%A = add %X, undef
%B = sub %X, undef
%C = xor %X, undef
Safe:
%A = undef
%B = undef
%C = undef
</pre>
<p>This is safe because all of the output bits are affected by the undef bits.
Any output bit can have a zero or one depending on the input bits.</p>
<pre class="doc_code">
%A = or %X, undef
%B = and %X, undef
Safe:
%A = -1
%B = 0
Unsafe:
%A = undef
%B = undef
</pre>
<p>These logical operations have bits that are not always affected by the input.
For example, if <tt>%X</tt> has a zero bit, then the output of the
'<tt>and</tt>' operation will always be a zero for that bit, no matter what
the corresponding bit from the '<tt>undef</tt>' is. As such, it is unsafe to
optimize or assume that the result of the '<tt>and</tt>' is '<tt>undef</tt>'.
However, it is safe to assume that all bits of the '<tt>undef</tt>' could be
0, and optimize the '<tt>and</tt>' to 0. Likewise, it is safe to assume that
all the bits of the '<tt>undef</tt>' operand to the '<tt>or</tt>' could be
set, allowing the '<tt>or</tt>' to be folded to -1.</p>
<pre class="doc_code">
%A = select undef, %X, %Y
%B = select undef, 42, %Y
%C = select %X, %Y, undef
Safe:
%A = %X (or %Y)
%B = 42 (or %Y)
%C = %Y
Unsafe:
%A = undef
%B = undef
%C = undef
</pre>
<p>This set of examples shows that undefined '<tt>select</tt>' (and conditional
branch) conditions can go <em>either way</em>, but they have to come from one
of the two operands. In the <tt>%A</tt> example, if <tt>%X</tt> and
<tt>%Y</tt> were both known to have a clear low bit, then <tt>%A</tt> would
have to have a cleared low bit. However, in the <tt>%C</tt> example, the
optimizer is allowed to assume that the '<tt>undef</tt>' operand could be the
same as <tt>%Y</tt>, allowing the whole '<tt>select</tt>' to be
eliminated.</p>
<pre class="doc_code">
%A = xor undef, undef
%B = undef
%C = xor %B, %B
%D = undef
%E = icmp lt %D, 4
%F = icmp gte %D, 4
Safe:
%A = undef
%B = undef
%C = undef
%D = undef
%E = undef
%F = undef
</pre>
<p>This example points out that two '<tt>undef</tt>' operands are not
necessarily the same. This can be surprising to people (and also matches C
semantics) where they assume that "<tt>X^X</tt>" is always zero, even
if <tt>X</tt> is undefined. This isn't true for a number of reasons, but the
short answer is that an '<tt>undef</tt>' "variable" can arbitrarily change
its value over its "live range". This is true because the variable doesn't
actually <em>have a live range</em>. Instead, the value is logically read
from arbitrary registers that happen to be around when needed, so the value
is not necessarily consistent over time. In fact, <tt>%A</tt> and <tt>%C</tt>
need to have the same semantics or the core LLVM "replace all uses with"
concept would not hold.</p>
<pre class="doc_code">
%A = fdiv undef, %X
%B = fdiv %X, undef
Safe:
%A = undef
b: unreachable
</pre>
<p>These examples show the crucial difference between an <em>undefined
value</em> and <em>undefined behavior</em>. An undefined value (like
'<tt>undef</tt>') is allowed to have an arbitrary bit-pattern. This means that
the <tt>%A</tt> operation can be constant folded to '<tt>undef</tt>', because
the '<tt>undef</tt>' could be an SNaN, and <tt>fdiv</tt> is not (currently)
defined on SNaN's. However, in the second example, we can make a more
aggressive assumption: because the <tt>undef</tt> is allowed to be an
arbitrary value, we are allowed to assume that it could be zero. Since a
divide by zero has <em>undefined behavior</em>, we are allowed to assume that
the operation does not execute at all. This allows us to delete the divide and
all code after it. Because the undefined operation "can't happen", the
optimizer can assume that it occurs in dead code.</p>
<pre class="doc_code">
a: store undef -> %X
b: store %X -> undef
Safe:
a: <deleted>
b: unreachable
</pre>
<p>These examples reiterate the <tt>fdiv</tt> example: a store <em>of</em> an
undefined value can be assumed to not have any effect; we can assume that the
value is overwritten with bits that happen to match what was already there.
However, a store <em>to</em> an undefined location could clobber arbitrary
memory, therefore, it has undefined behavior.</p>
</div>
<!-- ======================================================================= -->
<h3>
<a name="poisonvalues">Poison Values</a>
</h3>
<div>
<p>Poison values are similar to <a href="#undefvalues">undef values</a>, however
they also represent the fact that an instruction or constant expression which
cannot evoke side effects has nevertheless detected a condition which results
in undefined behavior.</p>
<p>There is currently no way of representing a poison value in the IR; they
only exist when produced by operations such as
<a href="#i_add"><tt>add</tt></a> with the <tt>nsw</tt> flag.</p>
<p>Poison value behavior is defined in terms of value <i>dependence</i>:</p>
<ul>
<li>Values other than <a href="#i_phi"><tt>phi</tt></a> nodes depend on
their operands.</li>
<li><a href="#i_phi"><tt>Phi</tt></a> nodes depend on the operand corresponding
to their dynamic predecessor basic block.</li>
<li>Function arguments depend on the corresponding actual argument values in
the dynamic callers of their functions.</li>
<li><a href="#i_call"><tt>Call</tt></a> instructions depend on the
<a href="#i_ret"><tt>ret</tt></a> instructions that dynamically transfer
control back to them.</li>
<li><a href="#i_invoke"><tt>Invoke</tt></a> instructions depend on the
<a href="#i_ret"><tt>ret</tt></a>, <a href="#i_resume"><tt>resume</tt></a>,
or exception-throwing call instructions that dynamically transfer control
back to them.</li>
<li>Non-volatile loads and stores depend on the most recent stores to all of the
referenced memory addresses, following the order in the IR
(including loads and stores implied by intrinsics such as
<a href="#int_memcpy"><tt>@llvm.memcpy</tt></a>.)</li>
<!-- TODO: In the case of multiple threads, this only applies if the store
"happens-before" the load or store. -->
<!-- TODO: floating-point exception state -->
<li>An instruction with externally visible side effects depends on the most
recent preceding instruction with externally visible side effects, following
the order in the IR. (This includes
<a href="#volatile">volatile operations</a>.)</li>
<li>An instruction <i>control-depends</i> on a
<a href="#terminators">terminator instruction</a>
if the terminator instruction has multiple successors and the instruction
is always executed when control transfers to one of the successors, and
may not be executed when control is transferred to another.</li>
<li>Additionally, an instruction also <i>control-depends</i> on a terminator
instruction if the set of instructions it otherwise depends on would be
different if the terminator had transferred control to a different
successor.</li>
<li>Dependence is transitive.</li>
</ul>
<p>Poison Values have the same behavior as <a href="#undefvalues">undef values</a>,
with the additional affect that any instruction which has a <i>dependence</i>
on a poison value has undefined behavior.</p>
<p>Here are some examples:</p>
<pre class="doc_code">
entry:
%poison = sub nuw i32 0, 1 ; Results in a poison value.
%still_poison = and i32 %poison, 0 ; 0, but also poison.
%poison_yet_again = getelementptr i32* @h, i32 %still_poison
store i32 0, i32* %poison_yet_again ; memory at @h[0] is poisoned
store i32 %poison, i32* @g ; Poison value stored to memory.
%poison2 = load i32* @g ; Poison value loaded back from memory.
store volatile i32 %poison, i32* @g ; External observation; undefined behavior.
%narrowaddr = bitcast i32* @g to i16*
%wideaddr = bitcast i32* @g to i64*
%poison3 = load i16* %narrowaddr ; Returns a poison value.
%poison4 = load i64* %wideaddr ; Returns a poison value.
%cmp = icmp slt i32 %poison, 0 ; Returns a poison value.
br i1 %cmp, label %true, label %end ; Branch to either destination.
true:
store volatile i32 0, i32* @g ; This is control-dependent on %cmp, so
; it has undefined behavior.
br label %end
end:
%p = phi i32 [ 0, %entry ], [ 1, %true ]
; Both edges into this PHI are
; control-dependent on %cmp, so this
; always results in a poison value.
store volatile i32 0, i32* @g ; This would depend on the store in %true
; if %cmp is true, or the store in %entry
; otherwise, so this is undefined behavior.
br i1 %cmp, label %second_true, label %second_end
; The same branch again, but this time the
; true block doesn't have side effects.
second_true:
; No side effects!
ret void
second_end:
store volatile i32 0, i32* @g ; This time, the instruction always depends
; on the store in %end. Also, it is
; control-equivalent to %end, so this is
; well-defined (ignoring earlier undefined
; behavior in this example).
</pre>
</div>
<!-- ======================================================================= -->
<h3>
<a name="blockaddress">Addresses of Basic Blocks</a>
</h3>
<div>
<p><b><tt>blockaddress(@function, %block)</tt></b></p>
<p>The '<tt>blockaddress</tt>' constant computes the address of the specified
basic block in the specified function, and always has an i8* type. Taking
the address of the entry block is illegal.</p>
<p>This value only has defined behavior when used as an operand to the
'<a href="#i_indirectbr"><tt>indirectbr</tt></a>' instruction, or for
comparisons against null. Pointer equality tests between labels addresses
results in undefined behavior — though, again, comparison against null
is ok, and no label is equal to the null pointer. This may be passed around
as an opaque pointer sized value as long as the bits are not inspected. This
allows <tt>ptrtoint</tt> and arithmetic to be performed on these values so
long as the original value is reconstituted before the <tt>indirectbr</tt>
instruction.</p>
<p>Finally, some targets may provide defined semantics when using the value as
the operand to an inline assembly, but that is target specific.</p>
</div>
<!-- ======================================================================= -->
<h3>
<a name="constantexprs">Constant Expressions</a>
</h3>
<div>
<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 than 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 than 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>fptoui (CST to TYPE)</tt></b></dt>
<dd>Convert a floating point constant to the corresponding unsigned integer
constant. TYPE must be a scalar or vector integer type. CST must be of
scalar or vector floating point type. Both CST and TYPE must be scalars,
or vectors of the same number of elements. 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 a scalar or vector integer type. CST must be of
scalar or vector floating point type. Both CST and TYPE must be scalars,
or vectors of the same number of elements. 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 a scalar or vector floating point type. CST must be
of scalar or vector integer type. Both CST and TYPE must be scalars, or
vectors of the same number of elements. 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 a scalar or vector floating point type. CST must be
of scalar or vector integer type. Both CST and TYPE must be scalars, or
vectors of the same number of elements. 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
<tt>TYPE</tt> must be an integer type. <tt>CST</tt> must be of pointer
type. The <tt>CST</tt> value is zero extended, truncated, or unchanged to
make it fit in <tt>TYPE</tt>.</dd>
<dt><b><tt>inttoptr (CST to TYPE)</tt></b></dt>
<dd>Convert an 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 constraints of the operands
are the same as those for the <a href="#i_bitcast">bitcast
instruction</a>.</dd>
<dt><b><tt>getelementptr (CSTPTR, IDX0, IDX1, ...)</tt></b></dt>
<dt><b><tt>getelementptr inbounds (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.</dd>
<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>extractvalue (VAL, IDX0, IDX1, ...)</tt></b></dt>
<dd>Perform the <a href="#i_extractvalue">extractvalue operation</a> on
constants. The index list is interpreted in a similar manner as indices in
a '<a href="#i_getelementptr">getelementptr</a>' operation. At least one
index value must be specified.</dd>
<dt><b><tt>insertvalue (VAL, ELT, IDX0, IDX1, ...)</tt></b></dt>
<dd>Perform the <a href="#i_insertvalue">insertvalue operation</a> on
constants. The index list is interpreted in a similar manner as indices in
a '<a href="#i_getelementptr">getelementptr</a>' operation. At least one
index value must be specified.</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>
<!-- *********************************************************************** -->
<h2><a name="othervalues">Other Values</a></h2>
<!-- *********************************************************************** -->
<div>
<!-- ======================================================================= -->
<h3>
<a name="inlineasm">Inline Assembler Expressions</a>
</h3>
<div>
<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), a flag that indicates whether or not the inline asm
expression has side effects, and a flag indicating whether the function
containing the asm needs to align its stack conservatively. An example
inline assembler expression is:</p>
<pre class="doc_code">
i32 (i32) asm "bswap $0", "=r,r"
</pre>
<p>Inline assembler expressions may <b>only</b> be used as the callee operand of
a <a href="#i_call"><tt>call</tt></a> or an
<a href="#i_invoke"><tt>invoke</tt></a> instruction.
Thus, typically we have:</p>
<pre class="doc_code">
%X = call i32 asm "<a href="#int_bswap">bswap</a> $0", "=r,r"(i32 %Y)
</pre>
<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>
<pre class="doc_code">
call void asm sideeffect "eieio", ""()
</pre>
<p>In some cases inline asms will contain code that will not work unless the
stack is aligned in some way, such as calls or SSE instructions on x86,
yet will not contain code that does that alignment within the asm.
The compiler should make conservative assumptions about what the asm might
contain and should generate its usual stack alignment code in the prologue
if the '<tt>alignstack</tt>' keyword is present:</p>
<pre class="doc_code">
call void asm alignstack "eieio", ""()
</pre>
<p>Inline asms also support using non-standard assembly dialects. The assumed
dialect is ATT. When the '<tt>inteldialect</tt>' keyword is present, the
inline asm is using the Intel dialect. Currently, ATT and Intel are the
only supported dialects. An example is:</p>
<pre class="doc_code">
call void asm inteldialect "eieio", ""()
</pre>
<p>If multiple keywords appear the '<tt>sideeffect</tt>' keyword must come
first, the '<tt>alignstack</tt>' keyword second and the
'<tt>inteldialect</tt>' keyword last.</p>
<!--
<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). This is probably best done by reference to
another document that covers inline asm from a holistic perspective.</p>
-->
<!-- _______________________________________________________________________ -->
<h4>
<a name="inlineasm_md">Inline Asm Metadata</a>
</h4>
<div>
<p>The call instructions that wrap inline asm nodes may have a
"<tt>!srcloc</tt>" MDNode attached to it that contains a list of constant
integers. If present, the code generator will use the integer as the
location cookie value when report errors through the <tt>LLVMContext</tt>
error reporting mechanisms. This allows a front-end to correlate backend
errors that occur with inline asm back to the source code that produced it.
For example:</p>
<pre class="doc_code">
call void asm sideeffect "something bad", ""()<b>, !srcloc !42</b>
...
!42 = !{ i32 1234567 }
</pre>
<p>It is up to the front-end to make sense of the magic numbers it places in the
IR. If the MDNode contains multiple constants, the code generator will use
the one that corresponds to the line of the asm that the error occurs on.</p>
</div>
</div>
<!-- ======================================================================= -->
<h3>
<a name="metadata">Metadata Nodes and Metadata Strings</a>
</h3>
<div>
<p>LLVM IR allows metadata to be attached to instructions in the program that
can convey extra information about the code to the optimizers and code
generator. One example application of metadata is source-level debug
information. There are two metadata primitives: strings and nodes. All
metadata has the <tt>metadata</tt> type and is identified in syntax by a
preceding exclamation point ('<tt>!</tt>').</p>
<p>A metadata string is a string surrounded by double quotes. It can contain
any character by escaping non-printable characters with "<tt>\xx</tt>" where
"<tt>xx</tt>" is the two digit hex code. For example:
"<tt>!"test\00"</tt>".</p>
<p>Metadata nodes are represented with notation similar to structure constants
(a comma separated list of elements, surrounded by braces and preceded by an
exclamation point). Metadata nodes can have any values as their operand. For
example:</p>
<div class="doc_code">
<pre>
!{ metadata !"test\00", i32 10}
</pre>
</div>
<p>A <a href="#namedmetadatastructure">named metadata</a> is a collection of
metadata nodes, which can be looked up in the module symbol table. For
example:</p>
<div class="doc_code">
<pre>
!foo = metadata !{!4, !3}
</pre>
</div>
<p>Metadata can be used as function arguments. Here <tt>llvm.dbg.value</tt>
function is using two metadata arguments:</p>
<div class="doc_code">
<pre>
call void @llvm.dbg.value(metadata !24, i64 0, metadata !25)
</pre>
</div>
<p>Metadata can be attached with an instruction. Here metadata <tt>!21</tt> is
attached to the <tt>add</tt> instruction using the <tt>!dbg</tt>
identifier:</p>
<div class="doc_code">
<pre>
%indvar.next = add i64 %indvar, 1, !dbg !21
</pre>
</div>
<p>More information about specific metadata nodes recognized by the optimizers
and code generator is found below.</p>
<!-- _______________________________________________________________________ -->
<h4>
<a name="tbaa">'<tt>tbaa</tt>' Metadata</a>
</h4>
<div>
<p>In LLVM IR, memory does not have types, so LLVM's own type system is not
suitable for doing TBAA. Instead, metadata is added to the IR to describe
a type system of a higher level language. This can be used to implement
typical C/C++ TBAA, but it can also be used to implement custom alias
analysis behavior for other languages.</p>
<p>The current metadata format is very simple. TBAA metadata nodes have up to
three fields, e.g.:</p>
<div class="doc_code">
<pre>
!0 = metadata !{ metadata !"an example type tree" }
!1 = metadata !{ metadata !"int", metadata !0 }
!2 = metadata !{ metadata !"float", metadata !0 }
!3 = metadata !{ metadata !"const float", metadata !2, i64 1 }
</pre>
</div>
<p>The first field is an identity field. It can be any value, usually
a metadata string, which uniquely identifies the type. The most important
name in the tree is the name of the root node. Two trees with
different root node names are entirely disjoint, even if they
have leaves with common names.</p>
<p>The second field identifies the type's parent node in the tree, or
is null or omitted for a root node. A type is considered to alias
all of its descendants and all of its ancestors in the tree. Also,
a type is considered to alias all types in other trees, so that
bitcode produced from multiple front-ends is handled conservatively.</p>
<p>If the third field is present, it's an integer which if equal to 1
indicates that the type is "constant" (meaning
<tt>pointsToConstantMemory</tt> should return true; see
<a href="AliasAnalysis.html#OtherItfs">other useful
<tt>AliasAnalysis</tt> methods</a>).</p>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="fpmath">'<tt>fpmath</tt>' Metadata</a>
</h4>
<div>
<p><tt>fpmath</tt> metadata may be attached to any instruction of floating point
type. It can be used to express the maximum acceptable error in the result of
that instruction, in ULPs, thus potentially allowing the compiler to use a
more efficient but less accurate method of computing it. ULP is defined as
follows:</p>
<blockquote>
<p>If <tt>x</tt> is a real number that lies between two finite consecutive
floating-point numbers <tt>a</tt> and <tt>b</tt>, without being equal to one
of them, then <tt>ulp(x) = |b - a|</tt>, otherwise <tt>ulp(x)</tt> is the
distance between the two non-equal finite floating-point numbers nearest
<tt>x</tt>. Moreover, <tt>ulp(NaN)</tt> is <tt>NaN</tt>.</p>
</blockquote>
<p>The metadata node shall consist of a single positive floating point number
representing the maximum relative error, for example:</p>
<div class="doc_code">
<pre>
!0 = metadata !{ float 2.5 } ; maximum acceptable inaccuracy is 2.5 ULPs
</pre>
</div>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="range">'<tt>range</tt>' Metadata</a>
</h4>
<div>
<p><tt>range</tt> metadata may be attached only to loads of integer types. It
expresses the possible ranges the loaded value is in. The ranges are
represented with a flattened list of integers. The loaded value is known to
be in the union of the ranges defined by each consecutive pair. Each pair
has the following properties:</p>
<ul>
<li>The type must match the type loaded by the instruction.</li>
<li>The pair <tt>a,b</tt> represents the range <tt>[a,b)</tt>.</li>
<li>Both <tt>a</tt> and <tt>b</tt> are constants.</li>
<li>The range is allowed to wrap.</li>
<li>The range should not represent the full or empty set. That is,
<tt>a!=b</tt>. </li>
</ul>
<p> In addition, the pairs must be in signed order of the lower bound and
they must be non-contiguous.</p>
<p>Examples:</p>
<div class="doc_code">
<pre>
%a = load i8* %x, align 1, !range !0 ; Can only be 0 or 1
%b = load i8* %y, align 1, !range !1 ; Can only be 255 (-1), 0 or 1
%c = load i8* %z, align 1, !range !2 ; Can only be 0, 1, 3, 4 or 5
%d = load i8* %z, align 1, !range !3 ; Can only be -2, -1, 3, 4 or 5
...
!0 = metadata !{ i8 0, i8 2 }
!1 = metadata !{ i8 255, i8 2 }
!2 = metadata !{ i8 0, i8 2, i8 3, i8 6 }
!3 = metadata !{ i8 -2, i8 0, i8 3, i8 6 }
</pre>
</div>
</div>
</div>
</div>
<!-- *********************************************************************** -->
<h2>
<a name="module_flags">Module Flags Metadata</a>
</h2>
<!-- *********************************************************************** -->
<div>
<p>Information about the module as a whole is difficult to convey to LLVM's
subsystems. The LLVM IR isn't sufficient to transmit this
information. The <tt>llvm.module.flags</tt> named metadata exists in order to
facilitate this. These flags are in the form of key / value pairs —
much like a dictionary — making it easy for any subsystem who cares
about a flag to look it up.</p>
<p>The <tt>llvm.module.flags</tt> metadata contains a list of metadata
triplets. Each triplet has the following form:</p>
<ul>
<li>The first element is a <i>behavior</i> flag, which specifies the behavior
when two (or more) modules are merged together, and it encounters two (or
more) metadata with the same ID. The supported behaviors are described
below.</li>
<li>The second element is a metadata string that is a unique ID for the
metadata. How each ID is interpreted is documented below.</li>
<li>The third element is the value of the flag.</li>
</ul>
<p>When two (or more) modules are merged together, the resulting
<tt>llvm.module.flags</tt> metadata is the union of the
modules' <tt>llvm.module.flags</tt> metadata. The only exception being a flag
with the <i>Override</i> behavior, which may override another flag's value
(see below).</p>
<p>The following behaviors are supported:</p>
<table border="1" cellspacing="0" cellpadding="4">
<tbody>
<tr>
<th>Value</th>
<th>Behavior</th>
</tr>
<tr>
<td>1</td>
<td align="left">
<dl>
<dt><b>Error</b></dt>
<dd>Emits an error if two values disagree. It is an error to have an ID
with both an Error and a Warning behavior.</dd>
</dl>
</td>
</tr>
<tr>
<td>2</td>
<td align="left">
<dl>
<dt><b>Warning</b></dt>
<dd>Emits a warning if two values disagree.</dd>
</dl>
</td>
</tr>
<tr>
<td>3</td>
<td align="left">
<dl>
<dt><b>Require</b></dt>
<dd>Emits an error when the specified value is not present or doesn't
have the specified value. It is an error for two (or more)
<tt>llvm.module.flags</tt> with the same ID to have the Require
behavior but different values. There may be multiple Require flags
per ID.</dd>
</dl>
</td>
</tr>
<tr>
<td>4</td>
<td align="left">
<dl>
<dt><b>Override</b></dt>
<dd>Uses the specified value if the two values disagree. It is an
error for two (or more) <tt>llvm.module.flags</tt> with the same
ID to have the Override behavior but different values.</dd>
</dl>
</td>
</tr>
</tbody>
</table>
<p>An example of module flags:</p>
<pre class="doc_code">
!0 = metadata !{ i32 1, metadata !"foo", i32 1 }
!1 = metadata !{ i32 4, metadata !"bar", i32 37 }
!2 = metadata !{ i32 2, metadata !"qux", i32 42 }
!3 = metadata !{ i32 3, metadata !"qux",
metadata !{
metadata !"foo", i32 1
}
}
!llvm.module.flags = !{ !0, !1, !2, !3 }
</pre>
<ul>
<li><p>Metadata <tt>!0</tt> has the ID <tt>!"foo"</tt> and the value '1'. The
behavior if two or more <tt>!"foo"</tt> flags are seen is to emit an
error if their values are not equal.</p></li>
<li><p>Metadata <tt>!1</tt> has the ID <tt>!"bar"</tt> and the value '37'. The
behavior if two or more <tt>!"bar"</tt> flags are seen is to use the
value '37' if their values are not equal.</p></li>
<li><p>Metadata <tt>!2</tt> has the ID <tt>!"qux"</tt> and the value '42'. The
behavior if two or more <tt>!"qux"</tt> flags are seen is to emit a
warning if their values are not equal.</p></li>
<li><p>Metadata <tt>!3</tt> has the ID <tt>!"qux"</tt> and the value:</p>
<pre class="doc_code">
metadata !{ metadata !"foo", i32 1 }
</pre>
<p>The behavior is to emit an error if the <tt>llvm.module.flags</tt> does
not contain a flag with the ID <tt>!"foo"</tt> that has the value
'1'. If two or more <tt>!"qux"</tt> flags exist, then they must have
the same value or an error will be issued.</p></li>
</ul>
<!-- ======================================================================= -->
<h3>
<a name="objc_gc_flags">Objective-C Garbage Collection Module Flags Metadata</a>
</h3>
<div>
<p>On the Mach-O platform, Objective-C stores metadata about garbage collection
in a special section called "image info". The metadata consists of a version
number and a bitmask specifying what types of garbage collection are
supported (if any) by the file. If two or more modules are linked together
their garbage collection metadata needs to be merged rather than appended
together.</p>
<p>The Objective-C garbage collection module flags metadata consists of the
following key-value pairs:</p>
<table border="1" cellspacing="0" cellpadding="4">
<col width="30%">
<tbody>
<tr>
<th>Key</th>
<th>Value</th>
</tr>
<tr>
<td><tt>Objective-C Version</tt></td>
<td align="left"><b>[Required]</b> — The Objective-C ABI
version. Valid values are 1 and 2.</td>
</tr>
<tr>
<td><tt>Objective-C Image Info Version</tt></td>
<td align="left"><b>[Required]</b> — The version of the image info
section. Currently always 0.</td>
</tr>
<tr>
<td><tt>Objective-C Image Info Section</tt></td>
<td align="left"><b>[Required]</b> — The section to place the
metadata. Valid values are <tt>"__OBJC, __image_info, regular"</tt> for
Objective-C ABI version 1, and <tt>"__DATA,__objc_imageinfo, regular,
no_dead_strip"</tt> for Objective-C ABI version 2.</td>
</tr>
<tr>
<td><tt>Objective-C Garbage Collection</tt></td>
<td align="left"><b>[Required]</b> — Specifies whether garbage
collection is supported or not. Valid values are 0, for no garbage
collection, and 2, for garbage collection supported.</td>
</tr>
<tr>
<td><tt>Objective-C GC Only</tt></td>
<td align="left"><b>[Optional]</b> — Specifies that only garbage
collection is supported. If present, its value must be 6. This flag
requires that the <tt>Objective-C Garbage Collection</tt> flag have the
value 2.</td>
</tr>
</tbody>
</table>
<p>Some important flag interactions:</p>
<ul>
<li>If a module with <tt>Objective-C Garbage Collection</tt> set to 0 is
merged with a module with <tt>Objective-C Garbage Collection</tt> set to
2, then the resulting module has the <tt>Objective-C Garbage
Collection</tt> flag set to 0.</li>
<li>A module with <tt>Objective-C Garbage Collection</tt> set to 0 cannot be
merged with a module with <tt>Objective-C GC Only</tt> set to 6.</li>
</ul>
</div>
</div>
<!-- *********************************************************************** -->
<h2>
<a name="intrinsic_globals">Intrinsic Global Variables</a>
</h2>
<!-- *********************************************************************** -->
<div>
<p>LLVM has a number of "magic" global variables that contain data that affect
code generation or other IR semantics. These are documented here. All globals
of this sort should have a section specified as "<tt>llvm.metadata</tt>". This
section and all globals that start with "<tt>llvm.</tt>" are reserved for use
by LLVM.</p>
<!-- ======================================================================= -->
<h3>
<a name="intg_used">The '<tt>llvm.used</tt>' Global Variable</a>
</h3>
<div>
<p>The <tt>@llvm.used</tt> global is an array with i8* element type which has <a
href="#linkage_appending">appending linkage</a>. This array contains a list of
pointers to global variables and functions which may optionally have a pointer
cast formed of bitcast or getelementptr. For example, a legal use of it is:</p>
<div class="doc_code">
<pre>
@X = global i8 4
@Y = global i32 123
@llvm.used = appending global [2 x i8*] [
i8* @X,
i8* bitcast (i32* @Y to i8*)
], section "llvm.metadata"
</pre>
</div>
<p>If a global variable appears in the <tt>@llvm.used</tt> list, then the
compiler, assembler, and linker are required to treat the symbol as if there
is a reference to the global that it cannot see. For example, if a variable
has internal linkage and no references other than that from
the <tt>@llvm.used</tt> list, it cannot be deleted. This is commonly used to
represent references from inline asms and other things the compiler cannot
"see", and corresponds to "<tt>attribute((used))</tt>" in GNU C.</p>
<p>On some targets, the code generator must emit a directive to the assembler or
object file to prevent the assembler and linker from molesting the
symbol.</p>
</div>
<!-- ======================================================================= -->
<h3>
<a name="intg_compiler_used">
The '<tt>llvm.compiler.used</tt>' Global Variable
</a>
</h3>
<div>
<p>The <tt>@llvm.compiler.used</tt> directive is the same as the
<tt>@llvm.used</tt> directive, except that it only prevents the compiler from
touching the symbol. On targets that support it, this allows an intelligent
linker to optimize references to the symbol without being impeded as it would
be by <tt>@llvm.used</tt>.</p>
<p>This is a rare construct that should only be used in rare circumstances, and
should not be exposed to source languages.</p>
</div>
<!-- ======================================================================= -->
<h3>
<a name="intg_global_ctors">The '<tt>llvm.global_ctors</tt>' Global Variable</a>
</h3>
<div>
<div class="doc_code">
<pre>
%0 = type { i32, void ()* }
@llvm.global_ctors = appending global [1 x %0] [%0 { i32 65535, void ()* @ctor }]
</pre>
</div>
<p>The <tt>@llvm.global_ctors</tt> array contains a list of constructor
functions and associated priorities. The functions referenced by this array
will be called in ascending order of priority (i.e. lowest first) when the
module is loaded. The order of functions with the same priority is not
defined.</p>
</div>
<!-- ======================================================================= -->
<h3>
<a name="intg_global_dtors">The '<tt>llvm.global_dtors</tt>' Global Variable</a>
</h3>
<div>
<div class="doc_code">
<pre>
%0 = type { i32, void ()* }
@llvm.global_dtors = appending global [1 x %0] [%0 { i32 65535, void ()* @dtor }]
</pre>
</div>
<p>The <tt>@llvm.global_dtors</tt> array contains a list of destructor functions
and associated priorities. The functions referenced by this array will be
called in descending order of priority (i.e. highest first) when the module
is loaded. The order of functions with the same priority is not defined.</p>
</div>
</div>
<!-- *********************************************************************** -->
<h2><a name="instref">Instruction Reference</a></h2>
<!-- *********************************************************************** -->
<div>
<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>
<!-- ======================================================================= -->
<h3>
<a name="terminators">Terminator Instructions</a>
</h3>
<div>
<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>The terminator instructions are:
'<a href="#i_ret"><tt>ret</tt></a>',
'<a href="#i_br"><tt>br</tt></a>',
'<a href="#i_switch"><tt>switch</tt></a>',
'<a href="#i_indirectbr"><tt>indirectbr</tt></a>',
'<a href="#i_invoke"><tt>invoke</tt></a>',
'<a href="#i_resume"><tt>resume</tt></a>', and
'<a href="#i_unreachable"><tt>unreachable</tt></a>'.</p>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_ret">'<tt>ret</tt>' Instruction</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
ret <type> <value> <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 optionally
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 optionally accepts a single argument, the
return value. The type of the return value must be a
'<a href="#t_firstclass">first class</a>' type.</p>
<p>A function is not <a href="#wellformed">well formed</a> if it it has a
non-void return type and contains a '<tt>ret</tt>' instruction with no return
value or a return value with a type that does not match its type, or if it
has a void return type and contains a '<tt>ret</tt>' instruction with a
return value.</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>
ret { i32, i8 } { i32 4, i8 2 } <i>; Return a struct of values 4 and 2</i>
</pre>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_br">'<tt>br</tt>' Instruction</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
br i1 <cond>, label <iftrue>, label <iffalse>
br label <dest> <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:
%cond = <a href="#i_icmp">icmp</a> eq i32 %a, %b
br i1 %cond, label %IfEqual, label %IfUnequal
IfEqual:
<a href="#i_ret">ret</a> i32 1
IfUnequal:
<a href="#i_ret">ret</a> i32 0
</pre>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_switch">'<tt>switch</tt>' Instruction</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
switch <intty> <value>, label <defaultdest> [ <intty> <val>, label <dest> ... ]
</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
transferred to the corresponding destination; otherwise, control flow is
transferred 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>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_indirectbr">'<tt>indirectbr</tt>' Instruction</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
indirectbr <somety>* <address>, [ label <dest1>, label <dest2>, ... ]
</pre>
<h5>Overview:</h5>
<p>The '<tt>indirectbr</tt>' instruction implements an indirect branch to a label
within the current function, whose address is specified by
"<tt>address</tt>". Address must be derived from a <a
href="#blockaddress">blockaddress</a> constant.</p>
<h5>Arguments:</h5>
<p>The '<tt>address</tt>' argument is the address of the label to jump to. The
rest of the arguments indicate the full set of possible destinations that the
address may point to. Blocks are allowed to occur multiple times in the
destination list, though this isn't particularly useful.</p>
<p>This destination list is required so that dataflow analysis has an accurate
understanding of the CFG.</p>
<h5>Semantics:</h5>
<p>Control transfers to the block specified in the address argument. All
possible destination blocks must be listed in the label list, otherwise this
instruction has undefined behavior. This implies that jumps to labels
defined in other functions have undefined behavior as well.</p>
<h5>Implementation:</h5>
<p>This is typically implemented with a jump through a register.</p>
<h5>Example:</h5>
<pre>
indirectbr i8* %Addr, [ label %bb1, label %bb2, label %bb3 ]
</pre>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_invoke">'<tt>invoke</tt>' Instruction</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
<result> = invoke [<a href="#callingconv">cconv</a>] [<a href="#paramattrs">ret attrs</a>] <ptr to function ty> <function ptr val>(<function args>) [<a href="#fnattrs">fn attrs</a>]
to label <normal label> unwind label <exception label>
</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 via the "<a href="#i_resume"><tt>resume</tt></a>"
instruction or other exception handling mechanism, control is interrupted and
continued at the dynamically nearest "exception" label.</p>
<p>The '<tt>exception</tt>' label is a
<i><a href="ExceptionHandling.html#overview">landing pad</a></i> for the
exception. As such, '<tt>exception</tt>' label is required to have the
"<a href="#i_landingpad"><tt>landingpad</tt></a>" instruction, which contains
the information about the behavior of the program after unwinding
happens, as its first non-PHI instruction. The restrictions on the
"<tt>landingpad</tt>" instruction's tightly couples it to the
"<tt>invoke</tt>" instruction, so that the important information contained
within the "<tt>landingpad</tt>" instruction can't be lost through normal
code motion.</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>The optional <a href="#paramattrs">Parameter Attributes</a> list for
return values. Only '<tt>zeroext</tt>', '<tt>signext</tt>', and
'<tt>inreg</tt>' attributes are valid here.</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 and parameter attributes. 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.</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 via
the <a href="#i_resume"><tt>resume</tt></a> instruction or other exception
handling mechanism.</li>
<li>The optional <a href="#fnattrs">function attributes</a> list. Only
'<tt>noreturn</tt>', '<tt>nounwind</tt>', '<tt>readonly</tt>' and
'<tt>readnone</tt>' attributes are valid here.</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>
<p>For the purposes of the SSA form, the definition of the value returned by the
'<tt>invoke</tt>' instruction is deemed to occur on the edge from the current
block to the "normal" label. If the callee unwinds then no return value is
available.</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 %Testfnptr(i32 15) to label %Continue
unwind label %TestCleanup <i>; {i32}:retval set</i>
</pre>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_resume">'<tt>resume</tt>' Instruction</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
resume <type> <value>
</pre>
<h5>Overview:</h5>
<p>The '<tt>resume</tt>' instruction is a terminator instruction that has no
successors.</p>
<h5>Arguments:</h5>
<p>The '<tt>resume</tt>' instruction requires one argument, which must have the
same type as the result of any '<tt>landingpad</tt>' instruction in the same
function.</p>
<h5>Semantics:</h5>
<p>The '<tt>resume</tt>' instruction resumes propagation of an existing
(in-flight) exception whose unwinding was interrupted with
a <a href="#i_landingpad"><tt>landingpad</tt></a> instruction.</p>
<h5>Example:</h5>
<pre>
resume { i8*, i32 } %exn
</pre>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_unreachable">'<tt>unreachable</tt>' Instruction</a>
</h4>
<div>
<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>
<!-- ======================================================================= -->
<h3>
<a name="binaryops">Binary Operations</a>
</h3>
<div>
<p>Binary operators are used to do most of the computation in a program. They
require two operands of the same type, 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
has the same type as its operands.</p>
<p>There are several different binary operators:</p>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_add">'<tt>add</tt>' Instruction</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
<result> = add <ty> <op1>, <op2> <i>; yields {ty}:result</i>
<result> = add nuw <ty> <op1>, <op2> <i>; yields {ty}:result</i>
<result> = add nsw <ty> <op1>, <op2> <i>; yields {ty}:result</i>
<result> = add nuw nsw <ty> <op1>, <op2> <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 <a href="#t_integer">integer</a> or <a href="#t_vector">vector</a> of
integer values. Both arguments must have identical types.</p>
<h5>Semantics:</h5>
<p>The value produced is the integer sum of the two operands.</p>
<p>If the sum has unsigned overflow, the result returned is the mathematical
result modulo 2<sup>n</sup>, where n is the bit width of the result.</p>
<p>Because LLVM integers use a two's complement representation, this instruction
is appropriate for both signed and unsigned integers.</p>
<p><tt>nuw</tt> and <tt>nsw</tt> stand for "No Unsigned Wrap"
and "No Signed Wrap", respectively. If the <tt>nuw</tt> and/or
<tt>nsw</tt> keywords are present, the result value of the <tt>add</tt>
is a <a href="#poisonvalues">poison value</a> if unsigned and/or signed overflow,
respectively, occurs.</p>
<h5>Example:</h5>
<pre>
<result> = add i32 4, %var <i>; yields {i32}:result = 4 + %var</i>
</pre>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_fadd">'<tt>fadd</tt>' Instruction</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
<result> = fadd <ty> <op1>, <op2> <i>; yields {ty}:result</i>
</pre>
<h5>Overview:</h5>
<p>The '<tt>fadd</tt>' instruction returns the sum of its two operands.</p>
<h5>Arguments:</h5>
<p>The two arguments to the '<tt>fadd</tt>' instruction must be
<a href="#t_floating">floating point</a> or <a href="#t_vector">vector</a> of
floating point values. Both arguments must have identical types.</p>
<h5>Semantics:</h5>
<p>The value produced is the floating point sum of the two operands.</p>
<h5>Example:</h5>
<pre>
<result> = fadd float 4.0, %var <i>; yields {float}:result = 4.0 + %var</i>
</pre>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_sub">'<tt>sub</tt>' Instruction</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
<result> = sub <ty> <op1>, <op2> <i>; yields {ty}:result</i>
<result> = sub nuw <ty> <op1>, <op2> <i>; yields {ty}:result</i>
<result> = sub nsw <ty> <op1>, <op2> <i>; yields {ty}:result</i>
<result> = sub nuw nsw <ty> <op1>, <op2> <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 <a href="#t_integer">integer</a> or <a href="#t_vector">vector</a> of
integer values. Both arguments must have identical types.</p>
<h5>Semantics:</h5>
<p>The value produced is the integer difference of the two operands.</p>
<p>If the difference has unsigned overflow, the result returned is the
mathematical result modulo 2<sup>n</sup>, where n is the bit width of the
result.</p>
<p>Because LLVM integers use a two's complement representation, this instruction
is appropriate for both signed and unsigned integers.</p>
<p><tt>nuw</tt> and <tt>nsw</tt> stand for "No Unsigned Wrap"
and "No Signed Wrap", respectively. If the <tt>nuw</tt> and/or
<tt>nsw</tt> keywords are present, the result value of the <tt>sub</tt>
is a <a href="#poisonvalues">poison value</a> if unsigned and/or signed overflow,
respectively, occurs.</p>
<h5>Example:</h5>
<pre>
<result> = sub i32 4, %var <i>; yields {i32}:result = 4 - %var</i>
<result> = sub i32 0, %val <i>; yields {i32}:result = -%var</i>
</pre>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_fsub">'<tt>fsub</tt>' Instruction</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
<result> = fsub <ty> <op1>, <op2> <i>; yields {ty}:result</i>
</pre>
<h5>Overview:</h5>
<p>The '<tt>fsub</tt>' instruction returns the difference of its two
operands.</p>
<p>Note that the '<tt>fsub</tt>' instruction is used to represent the
'<tt>fneg</tt>' instruction present in most other intermediate
representations.</p>
<h5>Arguments:</h5>
<p>The two arguments to the '<tt>fsub</tt>' instruction must be
<a href="#t_floating">floating point</a> or <a href="#t_vector">vector</a> of
floating point values. Both arguments must have identical types.</p>
<h5>Semantics:</h5>
<p>The value produced is the floating point difference of the two operands.</p>
<h5>Example:</h5>
<pre>
<result> = fsub float 4.0, %var <i>; yields {float}:result = 4.0 - %var</i>
<result> = fsub float -0.0, %val <i>; yields {float}:result = -%var</i>
</pre>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_mul">'<tt>mul</tt>' Instruction</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
<result> = mul <ty> <op1>, <op2> <i>; yields {ty}:result</i>
<result> = mul nuw <ty> <op1>, <op2> <i>; yields {ty}:result</i>
<result> = mul nsw <ty> <op1>, <op2> <i>; yields {ty}:result</i>
<result> = mul nuw nsw <ty> <op1>, <op2> <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 <a href="#t_integer">integer</a> or <a href="#t_vector">vector</a> of
integer values. Both arguments must have identical types.</p>
<h5>Semantics:</h5>
<p>The value produced is the integer product of the two operands.</p>
<p>If the result of the multiplication has unsigned overflow, the result
returned is the mathematical result modulo 2<sup>n</sup>, where n is the bit
width of the result.</p>
<p>Because LLVM integers use a two's complement representation, and the result
is the same width as the operands, this instruction returns the correct
result for both signed and unsigned integers. If a full product
(e.g. <tt>i32</tt>x<tt>i32</tt>-><tt>i64</tt>) is needed, the operands should
be sign-extended or zero-extended as appropriate to the width of the full
product.</p>
<p><tt>nuw</tt> and <tt>nsw</tt> stand for "No Unsigned Wrap"
and "No Signed Wrap", respectively. If the <tt>nuw</tt> and/or
<tt>nsw</tt> keywords are present, the result value of the <tt>mul</tt>
is a <a href="#poisonvalues">poison value</a> if unsigned and/or signed overflow,
respectively, occurs.</p>
<h5>Example:</h5>
<pre>
<result> = mul i32 4, %var <i>; yields {i32}:result = 4 * %var</i>
</pre>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_fmul">'<tt>fmul</tt>' Instruction</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
<result> = fmul <ty> <op1>, <op2> <i>; yields {ty}:result</i>
</pre>
<h5>Overview:</h5>
<p>The '<tt>fmul</tt>' instruction returns the product of its two operands.</p>
<h5>Arguments:</h5>
<p>The two arguments to the '<tt>fmul</tt>' instruction must be
<a href="#t_floating">floating point</a> or <a href="#t_vector">vector</a> of
floating point values. Both arguments must have identical types.</p>
<h5>Semantics:</h5>
<p>The value produced is the floating point product of the two operands.</p>
<h5>Example:</h5>
<pre>
<result> = fmul float 4.0, %var <i>; yields {float}:result = 4.0 * %var</i>
</pre>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_udiv">'<tt>udiv</tt>' Instruction</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
<result> = udiv <ty> <op1>, <op2> <i>; yields {ty}:result</i>
<result> = udiv exact <ty> <op1>, <op2> <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> or <a href="#t_vector">vector</a> of integer
values. Both arguments must have identical types.</p>
<h5>Semantics:</h5>
<p>The value produced is the unsigned integer quotient of the two operands.</p>
<p>Note that unsigned integer division and signed integer division are distinct
operations; for signed integer division, use '<tt>sdiv</tt>'.</p>
<p>Division by zero leads to undefined behavior.</p>
<p>If the <tt>exact</tt> keyword is present, the result value of the
<tt>udiv</tt> is a <a href="#poisonvalues">poison value</a> if %op1 is not a
multiple of %op2 (as such, "((a udiv exact b) mul b) == a").</p>
<h5>Example:</h5>
<pre>
<result> = udiv i32 4, %var <i>; yields {i32}:result = 4 / %var</i>
</pre>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_sdiv">'<tt>sdiv</tt>' Instruction</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
<result> = sdiv <ty> <op1>, <op2> <i>; yields {ty}:result</i>
<result> = sdiv exact <ty> <op1>, <op2> <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> or <a href="#t_vector">vector</a> of integer
values. Both arguments must have identical types.</p>
<h5>Semantics:</h5>
<p>The value produced is the signed integer quotient of the two operands rounded
towards zero.</p>
<p>Note that signed integer division and unsigned integer division are distinct
operations; for unsigned integer division, use '<tt>udiv</tt>'.</p>
<p>Division by zero leads to undefined behavior. Overflow also leads to
undefined behavior; this is a rare case, but can occur, for example, by doing
a 32-bit division of -2147483648 by -1.</p>
<p>If the <tt>exact</tt> keyword is present, the result value of the
<tt>sdiv</tt> is a <a href="#poisonvalues">poison value</a> if the result would
be rounded.</p>
<h5>Example:</h5>
<pre>
<result> = sdiv i32 4, %var <i>; yields {i32}:result = 4 / %var</i>
</pre>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_fdiv">'<tt>fdiv</tt>' Instruction</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
<result> = fdiv <ty> <op1>, <op2> <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> or <a href="#t_vector">vector</a> of
floating point values. Both arguments must have identical types.</p>
<h5>Semantics:</h5>
<p>The value produced is the floating point quotient of the two operands.</p>
<h5>Example:</h5>
<pre>
<result> = fdiv float 4.0, %var <i>; yields {float}:result = 4.0 / %var</i>
</pre>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_urem">'<tt>urem</tt>' Instruction</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
<result> = urem <ty> <op1>, <op2> <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> or <a href="#t_vector">vector</a> of integer
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.</p>
<p>Note that unsigned integer remainder and signed integer remainder are
distinct operations; for signed integer remainder, use '<tt>srem</tt>'.</p>
<p>Taking the remainder of a division by zero leads to undefined behavior.</p>
<h5>Example:</h5>
<pre>
<result> = urem i32 4, %var <i>; yields {i32}:result = 4 % %var</i>
</pre>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_srem">'<tt>srem</tt>' Instruction</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
<result> = srem <ty> <op1>, <op2> <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. 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>Arguments:</h5>
<p>The two arguments to the '<tt>srem</tt>' instruction must be
<a href="#t_integer">integer</a> or <a href="#t_vector">vector</a> of integer
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
is either zero or has the same sign as the dividend, <tt>op1</tt>), not the
<i>modulo</i> operator (where the result is either zero or has the same sign
as the divisor, <tt>op2</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>
<p>Note that signed integer remainder and unsigned integer remainder are
distinct operations; for unsigned integer remainder, use '<tt>urem</tt>'.</p>
<p>Taking the remainder of a division by zero leads to undefined behavior.
Overflow also leads to undefined behavior; this is a rare case, but can
occur, for example, by taking the remainder of a 32-bit division of
-2147483648 by -1. (The remainder doesn't actually overflow, but this rule
lets srem be implemented using instructions that return both the result of
the division and the remainder.)</p>
<h5>Example:</h5>
<pre>
<result> = srem i32 4, %var <i>; yields {i32}:result = 4 % %var</i>
</pre>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_frem">'<tt>frem</tt>' Instruction</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
<result> = frem <ty> <op1>, <op2> <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> or <a href="#t_vector">vector</a> of
floating point values. Both arguments must have identical types.</p>
<h5>Semantics:</h5>
<p>This instruction returns the <i>remainder</i> of a division. The remainder
has the same sign as the dividend.</p>
<h5>Example:</h5>
<pre>
<result> = frem float 4.0, %var <i>; yields {float}:result = 4.0 % %var</i>
</pre>
</div>
</div>
<!-- ======================================================================= -->
<h3>
<a name="bitwiseops">Bitwise Binary Operations</a>
</h3>
<div>
<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 of the
same type, execute an operation on them, and produce a single value. The
resulting value is the same type as its operands.</p>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_shl">'<tt>shl</tt>' Instruction</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
<result> = shl <ty> <op1>, <op2> <i>; yields {ty}:result</i>
<result> = shl nuw <ty> <op1>, <op2> <i>; yields {ty}:result</i>
<result> = shl nsw <ty> <op1>, <op2> <i>; yields {ty}:result</i>
<result> = shl nuw nsw <ty> <op1>, <op2> <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> or <a href="#t_vector">vector</a> of
integer type. '<tt>op2</tt>' is treated as an unsigned value.</p>
<h5>Semantics:</h5>
<p>The value produced is <tt>op1</tt> * 2<sup><tt>op2</tt></sup> mod
2<sup>n</sup>, where <tt>n</tt> is the width of the result. If <tt>op2</tt>
is (statically or dynamically) negative or equal to or larger than the number
of bits in <tt>op1</tt>, the result is undefined. If the arguments are
vectors, each vector element of <tt>op1</tt> is shifted by the corresponding
shift amount in <tt>op2</tt>.</p>
<p>If the <tt>nuw</tt> keyword is present, then the shift produces a
<a href="#poisonvalues">poison value</a> if it shifts out any non-zero bits. If
the <tt>nsw</tt> keyword is present, then the shift produces a
<a href="#poisonvalues">poison value</a> if it shifts out any bits that disagree
with the resultant sign bit. As such, NUW/NSW have the same semantics as
they would if the shift were expressed as a mul instruction with the same
nsw/nuw bits in (mul %op1, (shl 1, %op2)).</p>
<h5>Example:</h5>
<pre>
<result> = shl i32 4, %var <i>; yields {i32}: 4 << %var</i>
<result> = shl i32 4, 2 <i>; yields {i32}: 16</i>
<result> = shl i32 1, 10 <i>; yields {i32}: 1024</i>
<result> = shl i32 1, 32 <i>; undefined</i>
<result> = shl <2 x i32> < i32 1, i32 1>, < i32 1, i32 2> <i>; yields: result=<2 x i32> < i32 2, i32 4></i>
</pre>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_lshr">'<tt>lshr</tt>' Instruction</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
<result> = lshr <ty> <op1>, <op2> <i>; yields {ty}:result</i>
<result> = lshr exact <ty> <op1>, <op2> <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> or <a href="#t_vector">vector</a> of integer
type. '<tt>op2</tt>' is treated as an unsigned value.</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.
If <tt>op2</tt> is (statically or dynamically) equal to or larger than the
number of bits in <tt>op1</tt>, the result is undefined. If the arguments are
vectors, each vector element of <tt>op1</tt> is shifted by the corresponding
shift amount in <tt>op2</tt>.</p>
<p>If the <tt>exact</tt> keyword is present, the result value of the
<tt>lshr</tt> is a <a href="#poisonvalues">poison value</a> if any of the bits
shifted out are non-zero.</p>
<h5>Example:</h5>
<pre>
<result> = lshr i32 4, 1 <i>; yields {i32}:result = 2</i>
<result> = lshr i32 4, 2 <i>; yields {i32}:result = 1</i>
<result> = lshr i8 4, 3 <i>; yields {i8}:result = 0</i>
<result> = lshr i8 -2, 1 <i>; yields {i8}:result = 0x7FFFFFFF </i>
<result> = lshr i32 1, 32 <i>; undefined</i>
<result> = lshr <2 x i32> < i32 -2, i32 4>, < i32 1, i32 2> <i>; yields: result=<2 x i32> < i32 0x7FFFFFFF, i32 1></i>
</pre>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_ashr">'<tt>ashr</tt>' Instruction</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
<result> = ashr <ty> <op1>, <op2> <i>; yields {ty}:result</i>
<result> = ashr exact <ty> <op1>, <op2> <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> or <a href="#t_vector">vector</a> of integer
type. '<tt>op2</tt>' is treated as an unsigned value.</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>op1</tt>. If <tt>op2</tt> is (statically or dynamically) equal to or
larger than the number of bits in <tt>op1</tt>, the result is undefined. If
the arguments are vectors, each vector element of <tt>op1</tt> is shifted by
the corresponding shift amount in <tt>op2</tt>.</p>
<p>If the <tt>exact</tt> keyword is present, the result value of the
<tt>ashr</tt> is a <a href="#poisonvalues">poison value</a> if any of the bits
shifted out are non-zero.</p>
<h5>Example:</h5>
<pre>
<result> = ashr i32 4, 1 <i>; yields {i32}:result = 2</i>
<result> = ashr i32 4, 2 <i>; yields {i32}:result = 1</i>
<result> = ashr i8 4, 3 <i>; yields {i8}:result = 0</i>
<result> = ashr i8 -2, 1 <i>; yields {i8}:result = -1</i>
<result> = ashr i32 1, 32 <i>; undefined</i>
<result> = ashr <2 x i32> < i32 -2, i32 4>, < i32 1, i32 3> <i>; yields: result=<2 x i32> < i32 -1, i32 0></i>
</pre>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_and">'<tt>and</tt>' Instruction</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
<result> = and <ty> <op1>, <op2> <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> or <a href="#t_vector">vector</a> of integer
values. Both arguments must have identical types.</p>
<h5>Semantics:</h5>
<p>The truth table used for the '<tt>and</tt>' instruction is:</p>
<table border="1" cellspacing="0" cellpadding="4">
<tbody>
<tr>
<th>In0</th>
<th>In1</th>
<th>Out</th>
</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>
<h5>Example:</h5>
<pre>
<result> = and i32 4, %var <i>; yields {i32}:result = 4 & %var</i>
<result> = and i32 15, 40 <i>; yields {i32}:result = 8</i>
<result> = and i32 4, 8 <i>; yields {i32}:result = 0</i>
</pre>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_or">'<tt>or</tt>' Instruction</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
<result> = or <ty> <op1>, <op2> <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> or <a href="#t_vector">vector</a> of integer
values. Both arguments must have identical types.</p>
<h5>Semantics:</h5>
<p>The truth table used for the '<tt>or</tt>' instruction is:</p>
<table border="1" cellspacing="0" cellpadding="4">
<tbody>
<tr>
<th>In0</th>
<th>In1</th>
<th>Out</th>
</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>
<h5>Example:</h5>
<pre>
<result> = or i32 4, %var <i>; yields {i32}:result = 4 | %var</i>
<result> = or i32 15, 40 <i>; yields {i32}:result = 47</i>
<result> = or i32 4, 8 <i>; yields {i32}:result = 12</i>
</pre>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_xor">'<tt>xor</tt>' Instruction</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
<result> = xor <ty> <op1>, <op2> <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> or <a href="#t_vector">vector</a> of integer
values. Both arguments must have identical types.</p>
<h5>Semantics:</h5>
<p>The truth table used for the '<tt>xor</tt>' instruction is:</p>
<table border="1" cellspacing="0" cellpadding="4">
<tbody>
<tr>
<th>In0</th>
<th>In1</th>
<th>Out</th>
</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>
<h5>Example:</h5>
<pre>
<result> = xor i32 4, %var <i>; yields {i32}:result = 4 ^ %var</i>
<result> = xor i32 15, 40 <i>; yields {i32}:result = 39</i>
<result> = xor i32 4, 8 <i>; yields {i32}:result = 12</i>
<result> = xor i32 %V, -1 <i>; yields {i32}:result = ~%V</i>
</pre>
</div>
</div>
<!-- ======================================================================= -->
<h3>
<a name="vectorops">Vector Operations</a>
</h3>
<div>
<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>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_extractelement">'<tt>extractelement</tt>' Instruction</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
<result> = extractelement <n x <ty>> <val>, i32 <idx> <i>; yields <ty></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 <4 x i32> %vec, i32 0 <i>; yields i32</i>
</pre>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_insertelement">'<tt>insertelement</tt>' Instruction</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
<result> = insertelement <n x <ty>> <val>, <ty> <elt>, i32 <idx> <i>; yields <n x <ty>></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 <4 x i32> %vec, i32 1, i32 0 <i>; yields <4 x i32></i>
</pre>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_shufflevector">'<tt>shufflevector</tt>' Instruction</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
<result> = shufflevector <n x <ty>> <v1>, <n x <ty>> <v2>, <m x i32> <mask> <i>; yields <m x <ty>></i>
</pre>
<h5>Overview:</h5>
<p>The '<tt>shufflevector</tt>' instruction constructs a permutation of elements
from two input vectors, returning a vector with the same element type as the
input and length that is the same as the shuffle mask.</p>
<h5>Arguments:</h5>
<p>The first two operands of a '<tt>shufflevector</tt>' instruction are vectors
with the same type. The third argument is a shuffle mask whose
element type is always 'i32'. The result of the instruction is a vector
whose length is the same as the shuffle mask and whose element type is the
same as the element type of the first two operands.</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 vectors 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 <4 x i32> %v1, <4 x i32> %v2,
<4 x i32> <i32 0, i32 4, i32 1, i32 5> <i>; yields <4 x i32></i>
<result> = shufflevector <4 x i32> %v1, <4 x i32> undef,
<4 x i32> <i32 0, i32 1, i32 2, i32 3> <i>; yields <4 x i32></i> - Identity shuffle.
<result> = shufflevector <8 x i32> %v1, <8 x i32> undef,
<4 x i32> <i32 0, i32 1, i32 2, i32 3> <i>; yields <4 x i32></i>
<result> = shufflevector <4 x i32> %v1, <4 x i32> %v2,
<8 x i32> <i32 0, i32 1, i32 2, i32 3, i32 4, i32 5, i32 6, i32 7 > <i>; yields <8 x i32></i>
</pre>
</div>
</div>
<!-- ======================================================================= -->
<h3>
<a name="aggregateops">Aggregate Operations</a>
</h3>
<div>
<p>LLVM supports several instructions for working with
<a href="#t_aggregate">aggregate</a> values.</p>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_extractvalue">'<tt>extractvalue</tt>' Instruction</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
<result> = extractvalue <aggregate type> <val>, <idx>{, <idx>}*
</pre>
<h5>Overview:</h5>
<p>The '<tt>extractvalue</tt>' instruction extracts the value of a member field
from an <a href="#t_aggregate">aggregate</a> value.</p>
<h5>Arguments:</h5>
<p>The first operand of an '<tt>extractvalue</tt>' instruction is a value
of <a href="#t_struct">struct</a> or
<a href="#t_array">array</a> type. The operands are constant indices to
specify which value to extract in a similar manner as indices in a
'<tt><a href="#i_getelementptr">getelementptr</a></tt>' instruction.</p>
<p>The major differences to <tt>getelementptr</tt> indexing are:</p>
<ul>
<li>Since the value being indexed is not a pointer, the first index is
omitted and assumed to be zero.</li>
<li>At least one index must be specified.</li>
<li>Not only struct indices but also array indices must be in
bounds.</li>
</ul>
<h5>Semantics:</h5>
<p>The result is the value at the position in the aggregate specified by the
index operands.</p>
<h5>Example:</h5>
<pre>
<result> = extractvalue {i32, float} %agg, 0 <i>; yields i32</i>
</pre>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_insertvalue">'<tt>insertvalue</tt>' Instruction</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
<result> = insertvalue <aggregate type> <val>, <ty> <elt>, <idx>{, <idx>}* <i>; yields <aggregate type></i>
</pre>
<h5>Overview:</h5>
<p>The '<tt>insertvalue</tt>' instruction inserts a value into a member field
in an <a href="#t_aggregate">aggregate</a> value.</p>
<h5>Arguments:</h5>
<p>The first operand of an '<tt>insertvalue</tt>' instruction is a value
of <a href="#t_struct">struct</a> or
<a href="#t_array">array</a> type. The second operand is a first-class
value to insert. The following operands are constant indices indicating
the position at which to insert the value in a similar manner as indices in a
'<tt><a href="#i_extractvalue">extractvalue</a></tt>' instruction. The
value to insert must have the same type as the value identified by the
indices.</p>
<h5>Semantics:</h5>
<p>The result is an aggregate of the same type as <tt>val</tt>. Its value is
that of <tt>val</tt> except that the value at the position specified by the
indices is that of <tt>elt</tt>.</p>
<h5>Example:</h5>
<pre>
%agg1 = insertvalue {i32, float} undef, i32 1, 0 <i>; yields {i32 1, float undef}</i>
%agg2 = insertvalue {i32, float} %agg1, float %val, 1 <i>; yields {i32 1, float %val}</i>
%agg3 = insertvalue {i32, {float}} %agg1, float %val, 1, 0 <i>; yields {i32 1, float %val}</i>
</pre>
</div>
</div>
<!-- ======================================================================= -->
<h3>
<a name="memoryops">Memory Access and Addressing Operations</a>
</h3>
<div>
<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, and allocate
memory in LLVM.</p>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_alloca">'<tt>alloca</tt>' Instruction</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
<result> = alloca <type>[, <ty> <NumElements>][, align <alignment>] <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. The object is always allocated in the generic address
space (address space zero).</p>
<h5>Arguments:</h5>
<p>The '<tt>alloca</tt>' instruction
allocates <tt>sizeof(<type>)*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,
otherwise "NumElements" is defaulted to be one. If a constant 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 compatible with the
type.</p>
<p>'<tt>type</tt>' may be any sized type.</p>
<h5>Semantics:</h5>
<p>Memory is allocated; a pointer is returned. The operation is undefined if
there is insufficient stack space for the allocation. '<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_resume">resume</a></tt> instructions), the memory is
reclaimed. Allocating zero bytes is legal, but the result is undefined.
The order in which memory is allocated (ie., which way the stack grows) is
not specified.</p>
<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>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_load">'<tt>load</tt>' Instruction</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
<result> = load [volatile] <ty>* <pointer>[, align <alignment>][, !nontemporal !<index>][, !invariant.load !<index>]
<result> = load atomic [volatile] <ty>* <pointer> [singlethread] <ordering>, align <alignment>
!<index> = !{ i32 1 }
</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 <a
href="#volatile">volatile operations</a>.</p>
<p>If the <code>load</code> is marked as <code>atomic</code>, it takes an extra
<a href="#ordering">ordering</a> and optional <code>singlethread</code>
argument. The <code>release</code> and <code>acq_rel</code> orderings are
not valid on <code>load</code> instructions. Atomic loads produce <a
href="#memorymodel">defined</a> results when they may see multiple atomic
stores. The type of the pointee must be an integer type whose bit width
is a power of two greater than or equal to eight and less than or equal
to a target-specific size limit. <code>align</code> must be explicitly
specified on atomic loads, and the load has undefined behavior if the
alignment is not set to a value which is at least the size in bytes of
the pointee. <code>!nontemporal</code> does not have any defined semantics
for atomic loads.</p>
<p>The optional constant <tt>align</tt> argument specifies the alignment of the
operation (that is, the alignment of the memory address). A value of 0 or an
omitted <tt>align</tt> argument means that the operation has the preferential
alignment for the target. It is the responsibility of the code emitter to
ensure that the alignment information is correct. Overestimating the
alignment results in undefined behavior. Underestimating the alignment may
produce less efficient code. An alignment of 1 is always safe.</p>
<p>The optional <tt>!nontemporal</tt> metadata must reference a single
metatadata name <index> corresponding to a metadata node with
one <tt>i32</tt> entry of value 1. The existence of
the <tt>!nontemporal</tt> metatadata on the instruction tells the optimizer
and code generator that this load is not expected to be reused in the cache.
The code generator may select special instructions to save cache bandwidth,
such as the <tt>MOVNT</tt> instruction on x86.</p>
<p>The optional <tt>!invariant.load</tt> metadata must reference a single
metatadata name <index> corresponding to a metadata node with no
entries. The existence of the <tt>!invariant.load</tt> metatadata on the
instruction tells the optimizer and code generator that this load address
points to memory which does not change value during program execution.
The optimizer may then move this load around, for example, by hoisting it
out of loops using loop invariant code motion.</p>
<h5>Semantics:</h5>
<p>The location of memory pointed to is loaded. If the value being loaded is of
scalar type then the number of bytes read does not exceed the minimum number
of bytes needed to hold all bits of the type. For example, loading an
<tt>i24</tt> reads at most three bytes. When loading a value of a type like
<tt>i20</tt> with a size that is not an integral number of bytes, the result
is undefined if the value was not originally written using a store of the
same type.</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>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_store">'<tt>store</tt>' Instruction</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
store [volatile] <ty> <value>, <ty>* <pointer>[, align <alignment>][, !nontemporal !<index>] <i>; yields {void}</i>
store atomic [volatile] <ty> <value>, <ty>* <pointer> [singlethread] <ordering>, align <alignment> <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><pointer></tt>' operand must be a pointer to
the <a href="#t_firstclass">first class</a> type of the
'<tt><value></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 <a
href="#volatile">volatile operations</a>.</p>
<p>If the <code>store</code> is marked as <code>atomic</code>, it takes an extra
<a href="#ordering">ordering</a> and optional <code>singlethread</code>
argument. The <code>acquire</code> and <code>acq_rel</code> orderings aren't
valid on <code>store</code> instructions. Atomic loads produce <a
href="#memorymodel">defined</a> results when they may see multiple atomic
stores. The type of the pointee must be an integer type whose bit width
is a power of two greater than or equal to eight and less than or equal
to a target-specific size limit. <code>align</code> must be explicitly
specified on atomic stores, and the store has undefined behavior if the
alignment is not set to a value which is at least the size in bytes of
the pointee. <code>!nontemporal</code> does not have any defined semantics
for atomic stores.</p>
<p>The optional constant "align" argument specifies the alignment of the
operation (that is, the alignment of the memory address). A value of 0 or an
omitted "align" argument means that the operation has the preferential
alignment for the target. It is the responsibility of the code emitter to
ensure that the alignment information is correct. Overestimating the
alignment results in an undefined behavior. Underestimating the alignment may
produce less efficient code. An alignment of 1 is always safe.</p>
<p>The optional !nontemporal metadata must reference a single metatadata
name <index> corresponding to a metadata node with one i32 entry of
value 1. The existence of the !nontemporal metatadata on the
instruction tells the optimizer and code generator that this load is
not expected to be reused in the cache. The code generator may
select special instructions to save cache bandwidth, such as the
MOVNT instruction on x86.</p>
<h5>Semantics:</h5>
<p>The contents of memory are updated to contain '<tt><value></tt>' at the
location specified by the '<tt><pointer></tt>' operand. If
'<tt><value></tt>' is of scalar type then the number of bytes written
does not exceed the minimum number of bytes needed to hold all bits of the
type. For example, storing an <tt>i24</tt> writes at most three bytes. When
writing a value of a type like <tt>i20</tt> with a size that is not an
integral number of bytes, it is unspecified what happens to the extra bits
that do not belong to the type, but they will typically be overwritten.</p>
<h5>Example:</h5>
<pre>
%ptr = <a href="#i_alloca">alloca</a> i32 <i>; yields {i32*}:ptr</i>
store i32 3, i32* %ptr <i>; yields {void}</i>
%val = <a href="#i_load">load</a> i32* %ptr <i>; yields {i32}:val = i32 3</i>
</pre>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_fence">'<tt>fence</tt>' Instruction</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
fence [singlethread] <ordering> <i>; yields {void}</i>
</pre>
<h5>Overview:</h5>
<p>The '<tt>fence</tt>' instruction is used to introduce happens-before edges
between operations.</p>
<h5>Arguments:</h5> <p>'<code>fence</code>' instructions take an <a
href="#ordering">ordering</a> argument which defines what
<i>synchronizes-with</i> edges they add. They can only be given
<code>acquire</code>, <code>release</code>, <code>acq_rel</code>, and
<code>seq_cst</code> orderings.</p>
<h5>Semantics:</h5>
<p>A fence <var>A</var> which has (at least) <code>release</code> ordering
semantics <i>synchronizes with</i> a fence <var>B</var> with (at least)
<code>acquire</code> ordering semantics if and only if there exist atomic
operations <var>X</var> and <var>Y</var>, both operating on some atomic object
<var>M</var>, such that <var>A</var> is sequenced before <var>X</var>,
<var>X</var> modifies <var>M</var> (either directly or through some side effect
of a sequence headed by <var>X</var>), <var>Y</var> is sequenced before
<var>B</var>, and <var>Y</var> observes <var>M</var>. This provides a
<i>happens-before</i> dependency between <var>A</var> and <var>B</var>. Rather
than an explicit <code>fence</code>, one (but not both) of the atomic operations
<var>X</var> or <var>Y</var> might provide a <code>release</code> or
<code>acquire</code> (resp.) ordering constraint and still
<i>synchronize-with</i> the explicit <code>fence</code> and establish the
<i>happens-before</i> edge.</p>
<p>A <code>fence</code> which has <code>seq_cst</code> ordering, in addition to
having both <code>acquire</code> and <code>release</code> semantics specified
above, participates in the global program order of other <code>seq_cst</code>
operations and/or fences.</p>
<p>The optional "<a href="#singlethread"><code>singlethread</code></a>" argument
specifies that the fence only synchronizes with other fences in the same
thread. (This is useful for interacting with signal handlers.)</p>
<h5>Example:</h5>
<pre>
fence acquire <i>; yields {void}</i>
fence singlethread seq_cst <i>; yields {void}</i>
</pre>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_cmpxchg">'<tt>cmpxchg</tt>' Instruction</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
cmpxchg [volatile] <ty>* <pointer>, <ty> <cmp>, <ty> <new> [singlethread] <ordering> <i>; yields {ty}</i>
</pre>
<h5>Overview:</h5>
<p>The '<tt>cmpxchg</tt>' instruction is used to atomically modify memory.
It loads a value in memory and compares it to a given value. If they are
equal, it stores a new value into the memory.</p>
<h5>Arguments:</h5>
<p>There are three arguments to the '<code>cmpxchg</code>' instruction: an
address to operate on, a value to compare to the value currently be at that
address, and a new value to place at that address if the compared values are
equal. The type of '<var><cmp></var>' must be an integer type whose
bit width is a power of two greater than or equal to eight and less than
or equal to a target-specific size limit. '<var><cmp></var>' and
'<var><new></var>' must have the same type, and the type of
'<var><pointer></var>' must be a pointer to that type. If the
<code>cmpxchg</code> is marked as <code>volatile</code>, then the
optimizer is not allowed to modify the number or order of execution
of this <code>cmpxchg</code> with other <a href="#volatile">volatile
operations</a>.</p>
<!-- FIXME: Extend allowed types. -->
<p>The <a href="#ordering"><var>ordering</var></a> argument specifies how this
<code>cmpxchg</code> synchronizes with other atomic operations.</p>
<p>The optional "<code>singlethread</code>" argument declares that the
<code>cmpxchg</code> is only atomic with respect to code (usually signal
handlers) running in the same thread as the <code>cmpxchg</code>. Otherwise the
cmpxchg is atomic with respect to all other code in the system.</p>
<p>The pointer passed into cmpxchg must have alignment greater than or equal to
the size in memory of the operand.
<h5>Semantics:</h5>
<p>The contents of memory at the location specified by the
'<tt><pointer></tt>' operand is read and compared to
'<tt><cmp></tt>'; if the read value is the equal,
'<tt><new></tt>' is written. The original value at the location
is returned.
<p>A successful <code>cmpxchg</code> is a read-modify-write instruction for the
purpose of identifying <a href="#release_sequence">release sequences</a>. A
failed <code>cmpxchg</code> is equivalent to an atomic load with an ordering
parameter determined by dropping any <code>release</code> part of the
<code>cmpxchg</code>'s ordering.</p>
<!--
FIXME: Is compare_exchange_weak() necessary? (Consider after we've done
optimization work on ARM.)
FIXME: Is a weaker ordering constraint on failure helpful in practice?
-->
<h5>Example:</h5>
<pre>
entry:
%orig = atomic <a href="#i_load">load</a> i32* %ptr unordered <i>; yields {i32}</i>
<a href="#i_br">br</a> label %loop
loop:
%cmp = <a href="#i_phi">phi</a> i32 [ %orig, %entry ], [%old, %loop]
%squared = <a href="#i_mul">mul</a> i32 %cmp, %cmp
%old = cmpxchg i32* %ptr, i32 %cmp, i32 %squared <i>; yields {i32}</i>
%success = <a href="#i_icmp">icmp</a> eq i32 %cmp, %old
<a href="#i_br">br</a> i1 %success, label %done, label %loop
done:
...
</pre>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_atomicrmw">'<tt>atomicrmw</tt>' Instruction</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
atomicrmw [volatile] <operation> <ty>* <pointer>, <ty> <value> [singlethread] <ordering> <i>; yields {ty}</i>
</pre>
<h5>Overview:</h5>
<p>The '<tt>atomicrmw</tt>' instruction is used to atomically modify memory.</p>
<h5>Arguments:</h5>
<p>There are three arguments to the '<code>atomicrmw</code>' instruction: an
operation to apply, an address whose value to modify, an argument to the
operation. The operation must be one of the following keywords:</p>
<ul>
<li>xchg</li>
<li>add</li>
<li>sub</li>
<li>and</li>
<li>nand</li>
<li>or</li>
<li>xor</li>
<li>max</li>
<li>min</li>
<li>umax</li>
<li>umin</li>
</ul>
<p>The type of '<var><value></var>' must be an integer type whose
bit width is a power of two greater than or equal to eight and less than
or equal to a target-specific size limit. The type of the
'<code><pointer></code>' operand must be a pointer to that type.
If the <code>atomicrmw</code> is marked as <code>volatile</code>, then the
optimizer is not allowed to modify the number or order of execution of this
<code>atomicrmw</code> with other <a href="#volatile">volatile
operations</a>.</p>
<!-- FIXME: Extend allowed types. -->
<h5>Semantics:</h5>
<p>The contents of memory at the location specified by the
'<tt><pointer></tt>' operand are atomically read, modified, and written
back. The original value at the location is returned. The modification is
specified by the <var>operation</var> argument:</p>
<ul>
<li>xchg: <code>*ptr = val</code></li>
<li>add: <code>*ptr = *ptr + val</code></li>
<li>sub: <code>*ptr = *ptr - val</code></li>
<li>and: <code>*ptr = *ptr & val</code></li>
<li>nand: <code>*ptr = ~(*ptr & val)</code></li>
<li>or: <code>*ptr = *ptr | val</code></li>
<li>xor: <code>*ptr = *ptr ^ val</code></li>
<li>max: <code>*ptr = *ptr > val ? *ptr : val</code> (using a signed comparison)</li>
<li>min: <code>*ptr = *ptr < val ? *ptr : val</code> (using a signed comparison)</li>
<li>umax: <code>*ptr = *ptr > val ? *ptr : val</code> (using an unsigned comparison)</li>
<li>umin: <code>*ptr = *ptr < val ? *ptr : val</code> (using an unsigned comparison)</li>
</ul>
<h5>Example:</h5>
<pre>
%old = atomicrmw add i32* %ptr, i32 1 acquire <i>; yields {i32}</i>
</pre>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_getelementptr">'<tt>getelementptr</tt>' Instruction</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
<result> = getelementptr <pty>* <ptrval>{, <ty> <idx>}*
<result> = getelementptr inbounds <pty>* <ptrval>{, <ty> <idx>}*
<result> = getelementptr <ptr vector> ptrval, <vector index type> idx
</pre>
<h5>Overview:</h5>
<p>The '<tt>getelementptr</tt>' instruction is used to get the address of a
subelement of an <a href="#t_aggregate">aggregate</a> data structure.
It performs address calculation only and does not access memory.</p>
<h5>Arguments:</h5>
<p>The first argument is always a pointer or a vector of pointers,
and forms the basis of the
calculation. The remaining arguments are indices that indicate which of the
elements of the aggregate object are indexed. The interpretation of each
index is dependent on the type being indexed into. The first index always
indexes the pointer value given as the first argument, the second index
indexes a value of the type pointed to (not necessarily the value directly
pointed to, since the first index can be non-zero), etc. The first type
indexed into must be a pointer value, subsequent types can be arrays,
vectors, and structs. Note that subsequent types being indexed into
can never be pointers, since that would require loading the pointer before
continuing calculation.</p>
<p>The type of each index argument depends on the type it is indexing into.
When indexing into a (optionally packed) structure, only <tt>i32</tt>
integer <b>constants</b> are allowed. When indexing into an array, pointer
or vector, integers of any width are allowed, and they are not required to be
constant. These integers are treated as signed values where relevant.</p>
<p>For example, let's consider a C code fragment and how it gets compiled to
LLVM:</p>
<pre class="doc_code">
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 &s[1].Z.B[5][13];
}
</pre>
<p>The LLVM code generated by Clang is:</p>
<pre class="doc_code">
%struct.RT = <a href="#namedtypes">type</a> { i8, [10 x [20 x i32]], i8 }
%struct.ST = <a href="#namedtypes">type</a> { i32, double, %struct.RT }
define i32* @foo(%struct.ST* %s) nounwind uwtable readnone optsize ssp {
entry:
%arrayidx = getelementptr inbounds %struct.ST* %s, i64 1, i32 2, i32 1, i64 5, i64 13
ret i32* %arrayidx
}
</pre>
<h5>Semantics:</h5>
<p>In the example above, the first index is indexing into the
'<tt>%struct.ST*</tt>' type, which is a pointer, yielding a
'<tt>%struct.ST</tt>' = '<tt>{ i32, double, %struct.RT }</tt>' type, a
structure. The second index indexes into the third element of the structure,
yielding a '<tt>%struct.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 class="doc_code">
define i32* @foo(%struct.ST* %s) {
%t1 = getelementptr %struct.ST* %s, i32 1 <i>; yields %struct.ST*:%t1</i>
%t2 = getelementptr %struct.ST* %t1, i32 0, i32 2 <i>; yields %struct.RT*:%t2</i>
%t3 = getelementptr %struct.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>If the <tt>inbounds</tt> keyword is present, the result value of the
<tt>getelementptr</tt> is a <a href="#poisonvalues">poison value</a> if the
base pointer is not an <i>in bounds</i> address of an allocated object,
or if any of the addresses that would be formed by successive addition of
the offsets implied by the indices to the base address with infinitely
precise signed arithmetic are not an <i>in bounds</i> address of that
allocated object. The <i>in bounds</i> addresses for an allocated object
are all the addresses that point into the object, plus the address one
byte past the end.
In cases where the base is a vector of pointers the <tt>inbounds</tt> keyword
applies to each of the computations element-wise. </p>
<p>If the <tt>inbounds</tt> keyword is not present, the offsets are added to
the base address with silently-wrapping two's complement arithmetic. If the
offsets have a different width from the pointer, they are sign-extended or
truncated to the width of the pointer. The result value of the
<tt>getelementptr</tt> may be outside the object pointed to by the base
pointer. The result value may not necessarily be used to access memory
though, even if it happens to point into allocated storage. See the
<a href="#pointeraliasing">Pointer Aliasing Rules</a> section for more
information.</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]}* %saptr, i64 0, i32 1
<i>; yields i8*:vptr</i>
%vptr = getelementptr {i32, <2 x i8>}* %svptr, i64 0, i32 1, i32 1
<i>; yields i8*:eptr</i>
%eptr = getelementptr [12 x i8]* %aptr, i64 0, i32 1
<i>; yields i32*:iptr</i>
%iptr = getelementptr [10 x i32]* @arr, i16 0, i16 0
</pre>
<p>In cases where the pointer argument is a vector of pointers, only a
single index may be used, and the number of vector elements has to be
the same. For example: </p>
<pre class="doc_code">
%A = getelementptr <4 x i8*> %ptrs, <4 x i64> %offsets,
</pre>
</div>
</div>
<!-- ======================================================================= -->
<h3>
<a name="convertops">Conversion Operations</a>
</h3>
<div>
<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>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_trunc">'<tt>trunc .. to</tt>' Instruction</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
<result> = trunc <ty> <value> to <ty2> <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 value to trunc, and a type to trunc it to.
Both types must be of <a href="#t_integer">integer</a> types, or vectors
of the same number of integers.
The bit size of the <tt>value</tt> must be larger than
the bit size of the destination type, <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>
%Z = trunc i32 122 to i1 <i>; yields i1:false</i>
%W = trunc <2 x i16> <i16 8, i16 7> to <2 x i8> <i>; yields <i8 8, i8 7></i>
</pre>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_zext">'<tt>zext .. to</tt>' Instruction</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
<result> = zext <ty> <value> to <ty2> <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, and a type to cast it to.
Both types must be of <a href="#t_integer">integer</a> types, or vectors
of the same number of integers.
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>
%Z = zext <2 x i16> <i16 8, i16 7> to <2 x i32> <i>; yields <i32 8, i32 7></i>
</pre>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_sext">'<tt>sext .. to</tt>' Instruction</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
<result> = sext <ty> <value> to <ty2> <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, and a type to cast it to.
Both types must be of <a href="#t_integer">integer</a> types, or vectors
of the same number of integers.
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>
%Z = sext <2 x i16> <i16 8, i16 7> to <2 x i32> <i>; yields <i32 8, i32 7></i>
</pre>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_fptrunc">'<tt>fptrunc .. to</tt>' Instruction</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
<result> = fptrunc <ty> <value> to <ty2> <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>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_fpext">'<tt>fpext .. to</tt>' Instruction</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
<result> = fpext <ty> <value> to <ty2> <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 3.125 to double <i>; yields double:3.125000e+00</i>
%Y = fpext double %X to fp128 <i>; yields fp128:0xL00000000000000004000900000000000</i>
</pre>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_fptoui">'<tt>fptoui .. to</tt>' Instruction</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
<result> = fptoui <ty> <value> to <ty2> <i>; yields ty2</i>
</pre>
<h5>Overview:</h5>
<p>The '<tt>fptoui</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>fptoui</tt>' instruction takes a value to cast, which must be a
scalar or vector <a href="#t_floating">floating point</a> value, and a type
to cast it to <tt>ty2</tt>, which must be an <a href="#t_integer">integer</a>
type. If <tt>ty</tt> is a vector floating point type, <tt>ty2</tt> must be a
vector integer type with the same number of elements as <tt>ty</tt></p>
<h5>Semantics:</h5>
<p>The '<tt>fptoui</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>
<h5>Example:</h5>
<pre>
%X = fptoui double 123.0 to i32 <i>; yields i32:123</i>
%Y = fptoui float 1.0E+300 to i1 <i>; yields undefined:1</i>
%Z = fptoui float 1.04E+17 to i8 <i>; yields undefined:1</i>
</pre>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_fptosi">'<tt>fptosi .. to</tt>' Instruction</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
<result> = fptosi <ty> <value> to <ty2> <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
scalar or vector <a href="#t_floating">floating point</a> value, and a type
to cast it to <tt>ty2</tt>, which must be an <a href="#t_integer">integer</a>
type. If <tt>ty</tt> is a vector floating point type, <tt>ty2</tt> must be a
vector integer type with the same number of elements as <tt>ty</tt></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>
<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 undefined:1</i>
%Z = fptosi float 1.04E+17 to i8 <i>; yields undefined:1</i>
</pre>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_uitofp">'<tt>uitofp .. to</tt>' Instruction</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
<result> = uitofp <ty> <value> to <ty2> <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 a
scalar or vector <a href="#t_integer">integer</a> value, and a type to cast
it to <tt>ty2</tt>, which must be an <a href="#t_floating">floating point</a>
type. If <tt>ty</tt> is a vector integer type, <tt>ty2</tt> must be a vector
floating point type with the same number of elements as <tt>ty</tt></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>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_sitofp">'<tt>sitofp .. to</tt>' Instruction</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
<result> = sitofp <ty> <value> to <ty2> <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 a
scalar or vector <a href="#t_integer">integer</a> value, and a type to cast
it to <tt>ty2</tt>, which must be an <a href="#t_floating">floating point</a>
type. If <tt>ty</tt> is a vector integer type, <tt>ty2</tt> must be a vector
floating point type with the same number of elements as <tt>ty</tt></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>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_ptrtoint">'<tt>ptrtoint .. to</tt>' Instruction</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
<result> = ptrtoint <ty> <value> to <ty2> <i>; yields ty2</i>
</pre>
<h5>Overview:</h5>
<p>The '<tt>ptrtoint</tt>' instruction converts the pointer or a vector of
pointers <tt>value</tt> to
the integer (or vector of integers) 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 value of type <a href="#t_pointer">pointer</a> or a vector of
pointers, and a type to cast it to
<tt>ty2</tt>, which must be an <a href="#t_integer">integer</a> or a vector
of integers type.</p>
<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* %P to i8 <i>; yields truncation on 32-bit architecture</i>
%Y = ptrtoint i32* %P to i64 <i>; yields zero extension on 32-bit architecture</i>
%Z = ptrtoint <4 x i32*> %P to <4 x i64><i>; yields vector zero extension for a vector of addresses on 32-bit architecture</i>
</pre>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_inttoptr">'<tt>inttoptr .. to</tt>' Instruction</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
<result> = inttoptr <ty> <value> to <ty2> <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.</p>
<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>
%Y = inttoptr i32 255 to i32* <i>; yields no-op on 32-bit architecture</i>
%Z = inttoptr i64 0 to i32* <i>; yields truncation on 32-bit architecture</i>
%Z = inttoptr <4 x i32> %G to <4 x i8*><i>; yields truncation of vector G to four pointers</i>
</pre>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_bitcast">'<tt>bitcast .. to</tt>' Instruction</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
<result> = bitcast <ty> <value> to <ty2> <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
non-aggregate first class value, and a type to cast it to, which must also be
a non-aggregate <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. This instruction supports bitwise conversion of vectors to
integers and to vectors of other types (as long as they have the same
size).</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 (or vector of pointers) types may only be converted to other pointer
(or vector of pointers) 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 <2 x int> %V to i64; <i>; yields i64: %V</i>
%Z = bitcast <2 x i32*> %V to <2 x i64*> <i>; yields <2 x i64*></i>
</pre>
</div>
</div>
<!-- ======================================================================= -->
<h3>
<a name="otherops">Other Operations</a>
</h3>
<div>
<p>The instructions in this category are the "miscellaneous" instructions, which
defy better classification.</p>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_icmp">'<tt>icmp</tt>' Instruction</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
<result> = icmp <cond> <ty> <op1>, <op2> <i>; yields {i1} or {<N x i1>}:result</i>
</pre>
<h5>Overview:</h5>
<p>The '<tt>icmp</tt>' instruction returns a boolean value or a vector of
boolean values based on comparison of its two integer, integer vector,
pointer, or pointer vector 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:</p>
<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> or integer <a href="#t_vector">vector</a>
typed. They must also be identical types.</p>
<h5>Semantics:</h5>
<p>The '<tt>icmp</tt>' compares <tt>op1</tt> and <tt>op2</tt> according to the
condition code given as <tt>cond</tt>. The comparison performed always yields
either an <a href="#t_integer"><tt>i1</tt></a> or vector of <tt>i1</tt>
result, as follows:</p>
<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>
<li><tt>ugt</tt>: interprets the operands as unsigned values and yields
<tt>true</tt> if <tt>op1</tt> is greater than <tt>op2</tt>.</li>
<li><tt>uge</tt>: interprets the operands as unsigned values and yields
<tt>true</tt> if <tt>op1</tt> is greater than or equal
to <tt>op2</tt>.</li>
<li><tt>ult</tt>: interprets the operands as unsigned values and yields
<tt>true</tt> if <tt>op1</tt> is less than <tt>op2</tt>.</li>
<li><tt>ule</tt>: interprets the operands as unsigned values and yields
<tt>true</tt> if <tt>op1</tt> is less than or equal to <tt>op2</tt>.</li>
<li><tt>sgt</tt>: interprets the operands as signed values and yields
<tt>true</tt> if <tt>op1</tt> is greater than <tt>op2</tt>.</li>
<li><tt>sge</tt>: interprets the operands as signed values and yields
<tt>true</tt> if <tt>op1</tt> is greater than or equal
to <tt>op2</tt>.</li>
<li><tt>slt</tt>: interprets the operands as signed values and yields
<tt>true</tt> if <tt>op1</tt> is less than <tt>op2</tt>.</li>
<li><tt>sle</tt>: interprets the operands as signed values and yields
<tt>true</tt> if <tt>op1</tt> is less than or equal to <tt>op2</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>
<p>If the operands are integer vectors, then they are compared element by
element. The result is an <tt>i1</tt> vector with the same number of elements
as the values being compared. Otherwise, the result is an <tt>i1</tt>.</p>
<h5>Example:</h5>
<pre>
<result> = icmp eq i32 4, 5 <i>; yields: result=false</i>
<result> = icmp ne float* %X, %X <i>; yields: result=false</i>
<result> = icmp ult i16 4, 5 <i>; yields: result=true</i>
<result> = icmp sgt i16 4, 5 <i>; yields: result=false</i>
<result> = icmp ule i16 -4, 5 <i>; yields: result=false</i>
<result> = icmp sge i16 4, 5 <i>; yields: result=false</i>
</pre>
<p>Note that the code generator does not yet support vector types with
the <tt>icmp</tt> instruction.</p>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_fcmp">'<tt>fcmp</tt>' Instruction</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
<result> = fcmp <cond> <ty> <op1>, <op2> <i>; yields {i1} or {<N x i1>}:result</i>
</pre>
<h5>Overview:</h5>
<p>The '<tt>fcmp</tt>' instruction returns a boolean value or vector of boolean
values based on comparison of its operands.</p>
<p>If the operands are floating point scalars, then the result type is a boolean
(<a href="#t_integer"><tt>i1</tt></a>).</p>
<p>If the operands are floating point vectors, then the result type is a vector
of boolean with the same number of elements as the operands being
compared.</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:</p>
<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>Each of <tt>val1</tt> and <tt>val2</tt> arguments must be either
a <a href="#t_floating">floating point</a> type or
a <a href="#t_vector">vector</a> of floating point type. They must have
identical types.</p>
<h5>Semantics:</h5>
<p>The '<tt>fcmp</tt>' instruction compares <tt>op1</tt> and <tt>op2</tt>
according to the condition code given as <tt>cond</tt>. If the operands are
vectors, then the vectors are compared element by element. Each comparison
performed always yields an <a href="#t_integer">i1</a> result, as
follows:</p>
<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>op1</tt> is equal to <tt>op2</tt>.</li>
<li><tt>ogt</tt>: yields <tt>true</tt> if both operands are not a QNAN and
<tt>op1</tt> is greater than <tt>op2</tt>.</li>
<li><tt>oge</tt>: yields <tt>true</tt> if both operands are not a QNAN and
<tt>op1</tt> is greater than or equal to <tt>op2</tt>.</li>
<li><tt>olt</tt>: yields <tt>true</tt> if both operands are not a QNAN and
<tt>op1</tt> is less than <tt>op2</tt>.</li>
<li><tt>ole</tt>: yields <tt>true</tt> if both operands are not a QNAN and
<tt>op1</tt> is less than or equal to <tt>op2</tt>.</li>
<li><tt>one</tt>: yields <tt>true</tt> if both operands are not a QNAN and
<tt>op1</tt> is not equal to <tt>op2</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>op1</tt> is equal to <tt>op2</tt>.</li>
<li><tt>ugt</tt>: yields <tt>true</tt> if either operand is a QNAN or
<tt>op1</tt> is greater than <tt>op2</tt>.</li>
<li><tt>uge</tt>: yields <tt>true</tt> if either operand is a QNAN or
<tt>op1</tt> is greater than or equal to <tt>op2</tt>.</li>
<li><tt>ult</tt>: yields <tt>true</tt> if either operand is a QNAN or
<tt>op1</tt> is less than <tt>op2</tt>.</li>
<li><tt>ule</tt>: yields <tt>true</tt> if either operand is a QNAN or
<tt>op1</tt> is less than or equal to <tt>op2</tt>.</li>
<li><tt>une</tt>: yields <tt>true</tt> if either operand is a QNAN or
<tt>op1</tt> is not equal to <tt>op2</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>
<result> = fcmp oeq float 4.0, 5.0 <i>; yields: result=false</i>
<result> = fcmp one float 4.0, 5.0 <i>; yields: result=true</i>
<result> = fcmp olt float 4.0, 5.0 <i>; yields: result=true</i>
<result> = fcmp ueq double 1.0, 2.0 <i>; yields: result=false</i>
</pre>
<p>Note that the code generator does not yet support vector types with
the <tt>fcmp</tt> instruction.</p>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_phi">'<tt>phi</tt>' Instruction</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
<result> = phi <ty> [ <val0>, <label0>], ...
</pre>
<h5>Overview:</h5>
<p>The '<tt>phi</tt>' instruction is used to implement the φ 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>
<p>For the purposes of the SSA form, the use of each incoming value is deemed to
occur on the edge from the corresponding predecessor block to the current
block (but after any definition of an '<tt>invoke</tt>' instruction's return
value on the same edge).</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...
%indvar = phi i32 [ 0, %LoopHeader ], [ %nextindvar, %Loop ]
%nextindvar = add i32 %indvar, 1
br label %Loop
</pre>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_select">'<tt>select</tt>' Instruction</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
<result> = select <i>selty</i> <cond>, <ty> <val1>, <ty> <val2> <i>; yields ty</i>
<i>selty</i> is either i1 or {<N x i1>}
</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 an 'i1' value or a vector of 'i1'
values indicating the condition, and two values of the
same <a href="#t_firstclass">first class</a> type. If the val1/val2 are
vectors and the condition is a scalar, then entire vectors are selected, not
individual elements.</p>
<h5>Semantics:</h5>
<p>If the condition is an i1 and it evaluates to 1, the instruction returns the
first value argument; otherwise, it returns the second value argument.</p>
<p>If the condition is a vector of i1, then the value arguments must be vectors
of the same size, and the selection is done element by element.</p>
<h5>Example:</h5>
<pre>
%X = select i1 true, i8 17, i8 42 <i>; yields i8:17</i>
</pre>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_call">'<tt>call</tt>' Instruction</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
<result> = [tail] call [<a href="#callingconv">cconv</a>] [<a href="#paramattrs">ret attrs</a>] <ty> [<fnty>*] <fnptrval>(<function args>) [<a href="#fnattrs">fn attrs</a>]
</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>The optional "tail" marker indicates that the callee function does not
access any allocas or varargs in the caller. Note that calls may be
marked "tail" even if they do not occur before
a <a href="#i_ret"><tt>ret</tt></a> instruction. If the "tail" marker is
present, the function call is eligible for tail call optimization,
but <a href="CodeGenerator.html#tailcallopt">might not in fact be
optimized into a jump</a>. The code generator may optimize calls marked
"tail" with either 1) automatic <a href="CodeGenerator.html#sibcallopt">
sibling call optimization</a> when the caller and callee have
matching signatures, or 2) forced tail call optimization when the
following extra requirements are met:
<ul>
<li>Caller and callee both have the calling
convention <tt>fastcc</tt>.</li>
<li>The call is in tail position (ret immediately follows call and ret
uses value of call or is void).</li>
<li>Option <tt>-tailcallopt</tt> is enabled,
or <code>llvm::GuaranteedTailCallOpt</code> is <code>true</code>.</li>
<li><a href="CodeGenerator.html#tailcallopt">Platform specific
constraints are met.</a></li>
</ul>
</li>
<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. The calling convention of the
call must match the calling convention of the target function, or else the
behavior is undefined.</li>
<li>The optional <a href="#paramattrs">Parameter Attributes</a> list for
return values. Only '<tt>zeroext</tt>', '<tt>signext</tt>', and
'<tt>inreg</tt>' attributes are valid here.</li>
<li>'<tt>ty</tt>': the type of the call instruction itself which is also the
type of the return value. Functions that return no value are marked
<tt><a href="#t_void">void</a></tt>.</li>
<li>'<tt>fnty</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.</li>
<li>'<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.</li>
<li>'<tt>function args</tt>': argument list whose types match the function
signature argument types and parameter attributes. 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.</li>
<li>The optional <a href="#fnattrs">function attributes</a> list. Only
'<tt>noreturn</tt>', '<tt>nounwind</tt>', '<tt>readonly</tt>' and
'<tt>readnone</tt>' attributes are valid here.</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.</p>
<h5>Example:</h5>
<pre>
%retval = call i32 @test(i32 %argc)
call i32 (i8*, ...)* @printf(i8* %msg, i32 12, i8 42) <i>; yields i32</i>
%X = tail call i32 @foo() <i>; yields i32</i>
%Y = tail call <a href="#callingconv">fastcc</a> i32 @foo() <i>; yields i32</i>
call void %foo(i8 97 signext)
%struct.A = type { i32, i8 }
%r = call %struct.A @foo() <i>; yields { 32, i8 }</i>
%gr = extractvalue %struct.A %r, 0 <i>; yields i32</i>
%gr1 = extractvalue %struct.A %r, 1 <i>; yields i8</i>
%Z = call void @foo() noreturn <i>; indicates that %foo never returns normally</i>
%ZZ = call zeroext i32 @bar() <i>; Return value is %zero extended</i>
</pre>
<p>llvm treats calls to some functions with names and arguments that match the
standard C99 library as being the C99 library functions, and may perform
optimizations or generate code for them under that assumption. This is
something we'd like to change in the future to provide better support for
freestanding environments and non-C-based languages.</p>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_va_arg">'<tt>va_arg</tt>' Instruction</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
<resultval> = va_arg <va_list*> <arglist>, <argty>
</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>
<p>Note that the code generator does not yet fully support va_arg on many
targets. Also, it does not currently support va_arg with aggregate types on
any target.</p>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="i_landingpad">'<tt>landingpad</tt>' Instruction</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
<resultval> = landingpad <resultty> personality <type> <pers_fn> <clause>+
<resultval> = landingpad <resultty> personality <type> <pers_fn> cleanup <clause>*
<clause> := catch <type> <value>
<clause> := filter <array constant type> <array constant>
</pre>
<h5>Overview:</h5>
<p>The '<tt>landingpad</tt>' instruction is used by
<a href="ExceptionHandling.html#overview">LLVM's exception handling
system</a> to specify that a basic block is a landing pad — one where
the exception lands, and corresponds to the code found in the
<i><tt>catch</tt></i> portion of a <i><tt>try/catch</tt></i> sequence. It
defines values supplied by the personality function (<tt>pers_fn</tt>) upon
re-entry to the function. The <tt>resultval</tt> has the
type <tt>resultty</tt>.</p>
<h5>Arguments:</h5>
<p>This instruction takes a <tt>pers_fn</tt> value. This is the personality
function associated with the unwinding mechanism. The optional
<tt>cleanup</tt> flag indicates that the landing pad block is a cleanup.</p>
<p>A <tt>clause</tt> begins with the clause type — <tt>catch</tt>
or <tt>filter</tt> — and contains the global variable representing the
"type" that may be caught or filtered respectively. Unlike the
<tt>catch</tt> clause, the <tt>filter</tt> clause takes an array constant as
its argument. Use "<tt>[0 x i8**] undef</tt>" for a filter which cannot
throw. The '<tt>landingpad</tt>' instruction must contain <em>at least</em>
one <tt>clause</tt> or the <tt>cleanup</tt> flag.</p>
<h5>Semantics:</h5>
<p>The '<tt>landingpad</tt>' instruction defines the values which are set by the
personality function (<tt>pers_fn</tt>) upon re-entry to the function, and
therefore the "result type" of the <tt>landingpad</tt> instruction. As with
calling conventions, how the personality function results are represented in
LLVM IR is target specific.</p>
<p>The clauses are applied in order from top to bottom. If two
<tt>landingpad</tt> instructions are merged together through inlining, the
clauses from the calling function are appended to the list of clauses.
When the call stack is being unwound due to an exception being thrown, the
exception is compared against each <tt>clause</tt> in turn. If it doesn't
match any of the clauses, and the <tt>cleanup</tt> flag is not set, then
unwinding continues further up the call stack.</p>
<p>The <tt>landingpad</tt> instruction has several restrictions:</p>
<ul>
<li>A landing pad block is a basic block which is the unwind destination of an
'<tt>invoke</tt>' instruction.</li>
<li>A landing pad block must have a '<tt>landingpad</tt>' instruction as its
first non-PHI instruction.</li>
<li>There can be only one '<tt>landingpad</tt>' instruction within the landing
pad block.</li>
<li>A basic block that is not a landing pad block may not include a
'<tt>landingpad</tt>' instruction.</li>
<li>All '<tt>landingpad</tt>' instructions in a function must have the same
personality function.</li>
</ul>
<h5>Example:</h5>
<pre>
;; A landing pad which can catch an integer.
%res = landingpad { i8*, i32 } personality i32 (...)* @__gxx_personality_v0
catch i8** @_ZTIi
;; A landing pad that is a cleanup.
%res = landingpad { i8*, i32 } personality i32 (...)* @__gxx_personality_v0
cleanup
;; A landing pad which can catch an integer and can only throw a double.
%res = landingpad { i8*, i32 } personality i32 (...)* @__gxx_personality_v0
catch i8** @_ZTIi
filter [1 x i8**] [@_ZTId]
</pre>
</div>
</div>
</div>
<!-- *********************************************************************** -->
<h2><a name="intrinsics">Intrinsic Functions</a></h2>
<!-- *********************************************************************** -->
<div>
<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. Because LLVM can represent over 8 million different integer types,
overloading is used commonly to allow an intrinsic function to operate on any
integer type. One or more of the argument types or the result type can be
overloaded to accept any integer type. Argument types may also be defined as
exactly matching a previous argument's type or the result type. This allows
an intrinsic function which accepts multiple arguments, but needs all of them
to be of the same type, to only be overloaded with respect to a single
argument or the result.</p>
<p>Overloaded intrinsics will have the names of its overloaded argument types
encoded into its function name, each preceded by a period. Only those types
which are overloaded result in a name suffix. Arguments whose type is matched
against another type do not. For example, the <tt>llvm.ctpop</tt> function
can take an integer of any width and returns an integer of exactly the same
integer width. This leads to a family of functions such as
<tt>i8 @llvm.ctpop.i8(i8 %val)</tt> and <tt>i29 @llvm.ctpop.i29(i29
%val)</tt>. Only one type, the return type, is overloaded, and only one type
suffix is required. Because the argument's type is matched against the return
type, it does not require its own name suffix.</p>
<p>To learn how to add an intrinsic function, please see the
<a href="ExtendingLLVM.html">Extending LLVM Guide</a>.</p>
<!-- ======================================================================= -->
<h3>
<a name="int_varargs">Variable Argument Handling Intrinsics</a>
</h3>
<div>
<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><stdarg.h></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>
<pre class="doc_code">
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>
<!-- _______________________________________________________________________ -->
<h4>
<a name="int_va_start">'<tt>llvm.va_start</tt>' Intrinsic</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
declare void %llvm.va_start(i8* <arglist>)
</pre>
<h5>Overview:</h5>
<p>The '<tt>llvm.va_start</tt>' intrinsic initializes <tt>*<arglist></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>
<!-- _______________________________________________________________________ -->
<h4>
<a name="int_va_end">'<tt>llvm.va_end</tt>' Intrinsic</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
declare void @llvm.va_end(i8* <arglist>)
</pre>
<h5>Overview:</h5>
<p>The '<tt>llvm.va_end</tt>' intrinsic destroys <tt>*<arglist></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>
<!-- _______________________________________________________________________ -->
<h4>
<a name="int_va_copy">'<tt>llvm.va_copy</tt>' Intrinsic</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
declare void @llvm.va_copy(i8* <destarglist>, i8* <srcarglist>)
</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>
<!-- ======================================================================= -->
<h3>
<a name="int_gc">Accurate Garbage Collection Intrinsics</a>
</h3>
<div>
<p>LLVM support for <a href="GarbageCollection.html">Accurate Garbage
Collection</a> (GC) 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>
<p>The garbage collection intrinsics only operate on objects in the generic
address space (address space zero).</p>
<!-- _______________________________________________________________________ -->
<h4>
<a name="int_gcroot">'<tt>llvm.gcroot</tt>' Intrinsic</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
declare void @llvm.gcroot(i8** %ptrloc, i8* %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 intrinsic 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. The '<tt>llvm.gcroot</tt>'
intrinsic may only be used in a function which <a href="#gc">specifies a GC
algorithm</a>.</p>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="int_gcread">'<tt>llvm.gcread</tt>' Intrinsic</a>
</h4>
<div>
<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. The '<tt>llvm.gcread</tt>' intrinsic
may only be used in a function which <a href="#gc">specifies a GC
algorithm</a>.</p>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="int_gcwrite">'<tt>llvm.gcwrite</tt>' Intrinsic</a>
</h4>
<div>
<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. The '<tt>llvm.gcwrite</tt>' intrinsic
may only be used in a function which <a href="#gc">specifies a GC
algorithm</a>.</p>
</div>
</div>
<!-- ======================================================================= -->
<h3>
<a name="int_codegen">Code Generator Intrinsics</a>
</h3>
<div>
<p>These intrinsics are provided by LLVM to expose special features that may
only be implemented with code generator support.</p>
<!-- _______________________________________________________________________ -->
<h4>
<a name="int_returnaddress">'<tt>llvm.returnaddress</tt>' Intrinsic</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
declare i8 *@llvm.returnaddress(i32 <level>)
</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>
<!-- _______________________________________________________________________ -->
<h4>
<a name="int_frameaddress">'<tt>llvm.frameaddress</tt>' Intrinsic</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
declare i8* @llvm.frameaddress(i32 <level>)
</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>
<!-- _______________________________________________________________________ -->
<h4>
<a name="int_stacksave">'<tt>llvm.stacksave</tt>' Intrinsic</a>
</h4>
<div>
<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>
<!-- _______________________________________________________________________ -->
<h4>
<a name="int_stackrestore">'<tt>llvm.stackrestore</tt>' Intrinsic</a>
</h4>
<div>
<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>
<!-- _______________________________________________________________________ -->
<h4>
<a name="int_prefetch">'<tt>llvm.prefetch</tt>' Intrinsic</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
declare void @llvm.prefetch(i8* <address>, i32 <rw>, i32 <locality>, i32 <cache type>)
</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>cache type</tt>
specifies whether the prefetch is performed on the data (1) or instruction (0)
cache. The <tt>rw</tt>, <tt>locality</tt> and <tt>cache type</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>
<!-- _______________________________________________________________________ -->
<h4>
<a name="int_pcmarker">'<tt>llvm.pcmarker</tt>' Intrinsic</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
declare void @llvm.pcmarker(i32 <id>)
</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 intrinsic may ignore it.</p>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="int_readcyclecounter">'<tt>llvm.readcyclecounter</tt>' Intrinsic</a>
</h4>
<div>
<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>
<!-- ======================================================================= -->
<h3>
<a name="int_libc">Standard C Library Intrinsics</a>
</h3>
<div>
<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>
<!-- _______________________________________________________________________ -->
<h4>
<a name="int_memcpy">'<tt>llvm.memcpy</tt>' Intrinsic</a>
</h4>
<div>
<h5>Syntax:</h5>
<p>This is an overloaded intrinsic. You can use <tt>llvm.memcpy</tt> on any
integer bit width and for different address spaces. Not all targets support
all bit widths however.</p>
<pre>
declare void @llvm.memcpy.p0i8.p0i8.i32(i8* <dest>, i8* <src>,
i32 <len>, i32 <align>, i1 <isvolatile>)
declare void @llvm.memcpy.p0i8.p0i8.i64(i8* <dest>, i8* <src>,
i64 <len>, i32 <align>, i1 <isvolatile>)
</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, takes extra alignment/isvolatile arguments
and the pointers can be in specified address spaces.</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, the fourth argument is the alignment of the
source and destination locations, and the fifth is a boolean indicating a
volatile access.</p>
<p>If the call to this intrinsic 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>
<p>If the <tt>isvolatile</tt> parameter is <tt>true</tt>, the
<tt>llvm.memcpy</tt> call is a <a href="#volatile">volatile operation</a>.
The detailed access behavior is not very cleanly specified and it is unwise
to depend on it.</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>
<!-- _______________________________________________________________________ -->
<h4>
<a name="int_memmove">'<tt>llvm.memmove</tt>' Intrinsic</a>
</h4>
<div>
<h5>Syntax:</h5>
<p>This is an overloaded intrinsic. You can use llvm.memmove on any integer bit
width and for different address space. Not all targets support all bit
widths however.</p>
<pre>
declare void @llvm.memmove.p0i8.p0i8.i32(i8* <dest>, i8* <src>,
i32 <len>, i32 <align>, i1 <isvolatile>)
declare void @llvm.memmove.p0i8.p0i8.i64(i8* <dest>, i8* <src>,
i64 <len>, i32 <align>, i1 <isvolatile>)
</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.memcpy</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, takes extra alignment/isvolatile arguments
and the pointers can be in specified address spaces.</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, the fourth argument is the alignment of the
source and destination locations, and the fifth is a boolean indicating a
volatile access.</p>
<p>If the call to this intrinsic 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>
<p>If the <tt>isvolatile</tt> parameter is <tt>true</tt>, the
<tt>llvm.memmove</tt> call is a <a href="#volatile">volatile operation</a>.
The detailed access behavior is not very cleanly specified and it is unwise
to depend on it.</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>
<!-- _______________________________________________________________________ -->
<h4>
<a name="int_memset">'<tt>llvm.memset.*</tt>' Intrinsics</a>
</h4>
<div>
<h5>Syntax:</h5>
<p>This is an overloaded intrinsic. You can use llvm.memset on any integer bit
width and for different address spaces. However, not all targets support all
bit widths.</p>
<pre>
declare void @llvm.memset.p0i8.i32(i8* <dest>, i8 <val>,
i32 <len>, i32 <align>, i1 <isvolatile>)
declare void @llvm.memset.p0i8.i64(i8* <dest>, i8 <val>,
i64 <len>, i32 <align>, i1 <isvolatile>)
</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 extra alignment/volatile
arguments. Also, the destination can be in an arbitrary address space.</p>
<h5>Arguments:</h5>
<p>The first argument is a pointer to the destination to fill, the second is the
byte value with which to fill it, the third argument is an integer argument
specifying the number of bytes to fill, and the fourth argument is the known
alignment of the destination location.</p>
<p>If the call to this intrinsic has an alignment value that is not 0 or 1,
then the caller guarantees that the destination pointer is aligned to that
boundary.</p>
<p>If the <tt>isvolatile</tt> parameter is <tt>true</tt>, the
<tt>llvm.memset</tt> call is a <a href="#volatile">volatile operation</a>.
The detailed access behavior is not very cleanly specified and it is unwise
to depend on it.</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>
<!-- _______________________________________________________________________ -->
<h4>
<a name="int_sqrt">'<tt>llvm.sqrt.*</tt>' Intrinsic</a>
</h4>
<div>
<h5>Syntax:</h5>
<p>This is an overloaded intrinsic. You can use <tt>llvm.sqrt</tt> on any
floating point or vector of floating point type. Not all targets support all
types however.</p>
<pre>
declare float @llvm.sqrt.f32(float %Val)
declare double @llvm.sqrt.f64(double %Val)
declare x86_fp80 @llvm.sqrt.f80(x86_fp80 %Val)
declare fp128 @llvm.sqrt.f128(fp128 %Val)
declare ppc_fp128 @llvm.sqrt.ppcf128(ppc_fp128 %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>' functions would.
Unlike <tt>sqrt</tt> in libm, however, <tt>llvm.sqrt</tt> has undefined
behavior for negative numbers other than -0.0 (which allows for better
optimization, because there is no need to worry about errno being
set). <tt>llvm.sqrt(-0.0)</tt> is defined to return -0.0 like IEEE sqrt.</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>
<!-- _______________________________________________________________________ -->
<h4>
<a name="int_powi">'<tt>llvm.powi.*</tt>' Intrinsic</a>
</h4>
<div>
<h5>Syntax:</h5>
<p>This is an overloaded intrinsic. You can use <tt>llvm.powi</tt> on any
floating point or vector of floating point type. Not all targets support all
types however.</p>
<pre>
declare float @llvm.powi.f32(float %Val, i32 %power)
declare double @llvm.powi.f64(double %Val, i32 %power)
declare x86_fp80 @llvm.powi.f80(x86_fp80 %Val, i32 %power)
declare fp128 @llvm.powi.f128(fp128 %Val, i32 %power)
declare ppc_fp128 @llvm.powi.ppcf128(ppc_fp128 %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. When a vector of floating point type is
used, the second argument remains a scalar integer value.</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>
<!-- _______________________________________________________________________ -->
<h4>
<a name="int_sin">'<tt>llvm.sin.*</tt>' Intrinsic</a>
</h4>
<div>
<h5>Syntax:</h5>
<p>This is an overloaded intrinsic. You can use <tt>llvm.sin</tt> on any
floating point or vector of floating point type. Not all targets support all
types however.</p>
<pre>
declare float @llvm.sin.f32(float %Val)
declare double @llvm.sin.f64(double %Val)
declare x86_fp80 @llvm.sin.f80(x86_fp80 %Val)
declare fp128 @llvm.sin.f128(fp128 %Val)
declare ppc_fp128 @llvm.sin.ppcf128(ppc_fp128 %Val)
</pre>
<h5>Overview:</h5>
<p>The '<tt>llvm.sin.*</tt>' intrinsics return the sine of the operand.</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 sine of the specified operand, returning the same
values as the libm <tt>sin</tt> functions would, and handles error conditions
in the same way.</p>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="int_cos">'<tt>llvm.cos.*</tt>' Intrinsic</a>
</h4>
<div>
<h5>Syntax:</h5>
<p>This is an overloaded intrinsic. You can use <tt>llvm.cos</tt> on any
floating point or vector of floating point type. Not all targets support all
types however.</p>
<pre>
declare float @llvm.cos.f32(float %Val)
declare double @llvm.cos.f64(double %Val)
declare x86_fp80 @llvm.cos.f80(x86_fp80 %Val)
declare fp128 @llvm.cos.f128(fp128 %Val)
declare ppc_fp128 @llvm.cos.ppcf128(ppc_fp128 %Val)
</pre>
<h5>Overview:</h5>
<p>The '<tt>llvm.cos.*</tt>' intrinsics return the cosine of the operand.</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 cosine of the specified operand, returning the same
values as the libm <tt>cos</tt> functions would, and handles error conditions
in the same way.</p>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="int_pow">'<tt>llvm.pow.*</tt>' Intrinsic</a>
</h4>
<div>
<h5>Syntax:</h5>
<p>This is an overloaded intrinsic. You can use <tt>llvm.pow</tt> on any
floating point or vector of floating point type. Not all targets support all
types however.</p>
<pre>
declare float @llvm.pow.f32(float %Val, float %Power)
declare double @llvm.pow.f64(double %Val, double %Power)
declare x86_fp80 @llvm.pow.f80(x86_fp80 %Val, x86_fp80 %Power)
declare fp128 @llvm.pow.f128(fp128 %Val, fp128 %Power)
declare ppc_fp128 @llvm.pow.ppcf128(ppc_fp128 %Val, ppc_fp128 Power)
</pre>
<h5>Overview:</h5>
<p>The '<tt>llvm.pow.*</tt>' intrinsics return the first operand raised to the
specified (positive or negative) power.</p>
<h5>Arguments:</h5>
<p>The second argument is a floating point 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, returning
the same values as the libm <tt>pow</tt> functions would, and handles error
conditions in the same way.</p>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="int_exp">'<tt>llvm.exp.*</tt>' Intrinsic</a>
</h4>
<div>
<h5>Syntax:</h5>
<p>This is an overloaded intrinsic. You can use <tt>llvm.exp</tt> on any
floating point or vector of floating point type. Not all targets support all
types however.</p>
<pre>
declare float @llvm.exp.f32(float %Val)
declare double @llvm.exp.f64(double %Val)
declare x86_fp80 @llvm.exp.f80(x86_fp80 %Val)
declare fp128 @llvm.exp.f128(fp128 %Val)
declare ppc_fp128 @llvm.exp.ppcf128(ppc_fp128 %Val)
</pre>
<h5>Overview:</h5>
<p>The '<tt>llvm.exp.*</tt>' intrinsics perform the exp function.</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 same values as the libm <tt>exp</tt> functions
would, and handles error conditions in the same way.</p>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="int_log">'<tt>llvm.log.*</tt>' Intrinsic</a>
</h4>
<div>
<h5>Syntax:</h5>
<p>This is an overloaded intrinsic. You can use <tt>llvm.log</tt> on any
floating point or vector of floating point type. Not all targets support all
types however.</p>
<pre>
declare float @llvm.log.f32(float %Val)
declare double @llvm.log.f64(double %Val)
declare x86_fp80 @llvm.log.f80(x86_fp80 %Val)
declare fp128 @llvm.log.f128(fp128 %Val)
declare ppc_fp128 @llvm.log.ppcf128(ppc_fp128 %Val)
</pre>
<h5>Overview:</h5>
<p>The '<tt>llvm.log.*</tt>' intrinsics perform the log function.</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 same values as the libm <tt>log</tt> functions
would, and handles error conditions in the same way.</p>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="int_fma">'<tt>llvm.fma.*</tt>' Intrinsic</a>
</h4>
<div>
<h5>Syntax:</h5>
<p>This is an overloaded intrinsic. You can use <tt>llvm.fma</tt> on any
floating point or vector of floating point type. Not all targets support all
types however.</p>
<pre>
declare float @llvm.fma.f32(float %a, float %b, float %c)
declare double @llvm.fma.f64(double %a, double %b, double %c)
declare x86_fp80 @llvm.fma.f80(x86_fp80 %a, x86_fp80 %b, x86_fp80 %c)
declare fp128 @llvm.fma.f128(fp128 %a, fp128 %b, fp128 %c)
declare ppc_fp128 @llvm.fma.ppcf128(ppc_fp128 %a, ppc_fp128 %b, ppc_fp128 %c)
</pre>
<h5>Overview:</h5>
<p>The '<tt>llvm.fma.*</tt>' intrinsics perform the fused multiply-add
operation.</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 same values as the libm <tt>fma</tt> functions
would.</p>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="int_fabs">'<tt>llvm.fabs.*</tt>' Intrinsic</a>
</h4>
<div>
<h5>Syntax:</h5>
<p>This is an overloaded intrinsic. You can use <tt>llvm.fabs</tt> on any
floating point or vector of floating point type. Not all targets support all
types however.</p>
<pre>
declare float @llvm.fabs.f32(float %Val)
declare double @llvm.fabs.f64(double %Val)
declare x86_fp80 @llvm.fabs.f80(x86_fp80 %Val)
declare fp128 @llvm.fabs.f128(fp128 %Val)
declare ppc_fp128 @llvm.fabs.ppcf128(ppc_fp128 %Val)
</pre>
<h5>Overview:</h5>
<p>The '<tt>llvm.fabs.*</tt>' intrinsics return the absolute value of
the operand.</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 same values as the libm <tt>fabs</tt> functions
would, and handles error conditions in the same way.</p>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="int_floor">'<tt>llvm.floor.*</tt>' Intrinsic</a>
</h4>
<div>
<h5>Syntax:</h5>
<p>This is an overloaded intrinsic. You can use <tt>llvm.floor</tt> on any
floating point or vector of floating point type. Not all targets support all
types however.</p>
<pre>
declare float @llvm.floor.f32(float %Val)
declare double @llvm.floor.f64(double %Val)
declare x86_fp80 @llvm.floor.f80(x86_fp80 %Val)
declare fp128 @llvm.floor.f128(fp128 %Val)
declare ppc_fp128 @llvm.floor.ppcf128(ppc_fp128 %Val)
</pre>
<h5>Overview:</h5>
<p>The '<tt>llvm.floor.*</tt>' intrinsics return the floor of
the operand.</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 same values as the libm <tt>floor</tt> functions
would, and handles error conditions in the same way.</p>
</div>
</div>
<!-- ======================================================================= -->
<h3>
<a name="int_manip">Bit Manipulation Intrinsics</a>
</h3>
<div>
<p>LLVM provides intrinsics for a few important bit manipulation operations.
These allow efficient code generation for some algorithms.</p>
<!-- _______________________________________________________________________ -->
<h4>
<a name="int_bswap">'<tt>llvm.bswap.*</tt>' Intrinsics</a>
</h4>
<div>
<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).</p>
<pre>
declare i16 @llvm.bswap.i16(i16 <id>)
declare i32 @llvm.bswap.i32(i32 <id>)
declare i64 @llvm.bswap.i64(i64 <id>)
</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.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</tt>, <tt>llvm.bswap.i64</tt> and other intrinsics
extend this concept to additional even-byte lengths (6 bytes, 8 bytes and
more, respectively).</p>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="int_ctpop">'<tt>llvm.ctpop.*</tt>' Intrinsic</a>
</h4>
<div>
<h5>Syntax:</h5>
<p>This is an overloaded intrinsic. You can use llvm.ctpop on any integer bit
width, or on any vector with integer elements. Not all targets support all
bit widths or vector types, however.</p>
<pre>
declare i8 @llvm.ctpop.i8(i8 <src>)
declare i16 @llvm.ctpop.i16(i16 <src>)
declare i32 @llvm.ctpop.i32(i32 <src>)
declare i64 @llvm.ctpop.i64(i64 <src>)
declare i256 @llvm.ctpop.i256(i256 <src>)
declare <2 x i32> @llvm.ctpop.v2i32(<2 x i32> <src>)
</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, or a vector with integer elements.
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, or within each
element of a vector.</p>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="int_ctlz">'<tt>llvm.ctlz.*</tt>' Intrinsic</a>
</h4>
<div>
<h5>Syntax:</h5>
<p>This is an overloaded intrinsic. You can use <tt>llvm.ctlz</tt> on any
integer bit width, or any vector whose elements are integers. Not all
targets support all bit widths or vector types, however.</p>
<pre>
declare i8 @llvm.ctlz.i8 (i8 <src>, i1 <is_zero_undef>)
declare i16 @llvm.ctlz.i16 (i16 <src>, i1 <is_zero_undef>)
declare i32 @llvm.ctlz.i32 (i32 <src>, i1 <is_zero_undef>)
declare i64 @llvm.ctlz.i64 (i64 <src>, i1 <is_zero_undef>)
declare i256 @llvm.ctlz.i256(i256 <src>, i1 <is_zero_undef>)
declase <2 x i32> @llvm.ctlz.v2i32(<2 x i32> <src>, i1 <is_zero_undef>)
</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 first argument is the value to be counted. This argument may be of any
integer type, or a vectory with integer element type. The return type
must match the first argument type.</p>
<p>The second argument must be a constant and is a flag to indicate whether the
intrinsic should ensure that a zero as the first argument produces a defined
result. Historically some architectures did not provide a defined result for
zero values as efficiently, and many algorithms are now predicated on
avoiding zero-value inputs.</p>
<h5>Semantics:</h5>
<p>The '<tt>llvm.ctlz</tt>' intrinsic counts the leading (most significant)
zeros in a variable, or within each element of the vector.
If <tt>src == 0</tt> then the result is the size in bits of the type of
<tt>src</tt> if <tt>is_zero_undef == 0</tt> and <tt>undef</tt> otherwise.
For example, <tt>llvm.ctlz(i32 2) = 30</tt>.</p>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="int_cttz">'<tt>llvm.cttz.*</tt>' Intrinsic</a>
</h4>
<div>
<h5>Syntax:</h5>
<p>This is an overloaded intrinsic. You can use <tt>llvm.cttz</tt> on any
integer bit width, or any vector of integer elements. Not all targets
support all bit widths or vector types, however.</p>
<pre>
declare i8 @llvm.cttz.i8 (i8 <src>, i1 <is_zero_undef>)
declare i16 @llvm.cttz.i16 (i16 <src>, i1 <is_zero_undef>)
declare i32 @llvm.cttz.i32 (i32 <src>, i1 <is_zero_undef>)
declare i64 @llvm.cttz.i64 (i64 <src>, i1 <is_zero_undef>)
declare i256 @llvm.cttz.i256(i256 <src>, i1 <is_zero_undef>)
declase <2 x i32> @llvm.cttz.v2i32(<2 x i32> <src>, i1 <is_zero_undef>)
</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 first argument is the value to be counted. This argument may be of any
integer type, or a vectory with integer element type. The return type
must match the first argument type.</p>
<p>The second argument must be a constant and is a flag to indicate whether the
intrinsic should ensure that a zero as the first argument produces a defined
result. Historically some architectures did not provide a defined result for
zero values as efficiently, and many algorithms are now predicated on
avoiding zero-value inputs.</p>
<h5>Semantics:</h5>
<p>The '<tt>llvm.cttz</tt>' intrinsic counts the trailing (least significant)
zeros in a variable, or within each element of a vector.
If <tt>src == 0</tt> then the result is the size in bits of the type of
<tt>src</tt> if <tt>is_zero_undef == 0</tt> and <tt>undef</tt> otherwise.
For example, <tt>llvm.cttz(2) = 1</tt>.</p>
</div>
</div>
<!-- ======================================================================= -->
<h3>
<a name="int_overflow">Arithmetic with Overflow Intrinsics</a>
</h3>
<div>
<p>LLVM provides intrinsics for some arithmetic with overflow operations.</p>
<!-- _______________________________________________________________________ -->
<h4>
<a name="int_sadd_overflow">
'<tt>llvm.sadd.with.overflow.*</tt>' Intrinsics
</a>
</h4>
<div>
<h5>Syntax:</h5>
<p>This is an overloaded intrinsic. You can use <tt>llvm.sadd.with.overflow</tt>
on any integer bit width.</p>
<pre>
declare {i16, i1} @llvm.sadd.with.overflow.i16(i16 %a, i16 %b)
declare {i32, i1} @llvm.sadd.with.overflow.i32(i32 %a, i32 %b)
declare {i64, i1} @llvm.sadd.with.overflow.i64(i64 %a, i64 %b)
</pre>
<h5>Overview:</h5>
<p>The '<tt>llvm.sadd.with.overflow</tt>' family of intrinsic functions perform
a signed addition of the two arguments, and indicate whether an overflow
occurred during the signed summation.</p>
<h5>Arguments:</h5>
<p>The arguments (%a and %b) and the first element of the result structure may
be of integer types of any bit width, but they must have the same bit
width. The second element of the result structure must be of
type <tt>i1</tt>. <tt>%a</tt> and <tt>%b</tt> are the two values that will
undergo signed addition.</p>
<h5>Semantics:</h5>
<p>The '<tt>llvm.sadd.with.overflow</tt>' family of intrinsic functions perform
a signed addition of the two variables. They return a structure — the
first element of which is the signed summation, and the second element of
which is a bit specifying if the signed summation resulted in an
overflow.</p>
<h5>Examples:</h5>
<pre>
%res = call {i32, i1} @llvm.sadd.with.overflow.i32(i32 %a, i32 %b)
%sum = extractvalue {i32, i1} %res, 0
%obit = extractvalue {i32, i1} %res, 1
br i1 %obit, label %overflow, label %normal
</pre>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="int_uadd_overflow">
'<tt>llvm.uadd.with.overflow.*</tt>' Intrinsics
</a>
</h4>
<div>
<h5>Syntax:</h5>
<p>This is an overloaded intrinsic. You can use <tt>llvm.uadd.with.overflow</tt>
on any integer bit width.</p>
<pre>
declare {i16, i1} @llvm.uadd.with.overflow.i16(i16 %a, i16 %b)
declare {i32, i1} @llvm.uadd.with.overflow.i32(i32 %a, i32 %b)
declare {i64, i1} @llvm.uadd.with.overflow.i64(i64 %a, i64 %b)
</pre>
<h5>Overview:</h5>
<p>The '<tt>llvm.uadd.with.overflow</tt>' family of intrinsic functions perform
an unsigned addition of the two arguments, and indicate whether a carry
occurred during the unsigned summation.</p>
<h5>Arguments:</h5>
<p>The arguments (%a and %b) and the first element of the result structure may
be of integer types of any bit width, but they must have the same bit
width. The second element of the result structure must be of
type <tt>i1</tt>. <tt>%a</tt> and <tt>%b</tt> are the two values that will
undergo unsigned addition.</p>
<h5>Semantics:</h5>
<p>The '<tt>llvm.uadd.with.overflow</tt>' family of intrinsic functions perform
an unsigned addition of the two arguments. They return a structure —
the first element of which is the sum, and the second element of which is a
bit specifying if the unsigned summation resulted in a carry.</p>
<h5>Examples:</h5>
<pre>
%res = call {i32, i1} @llvm.uadd.with.overflow.i32(i32 %a, i32 %b)
%sum = extractvalue {i32, i1} %res, 0
%obit = extractvalue {i32, i1} %res, 1
br i1 %obit, label %carry, label %normal
</pre>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="int_ssub_overflow">
'<tt>llvm.ssub.with.overflow.*</tt>' Intrinsics
</a>
</h4>
<div>
<h5>Syntax:</h5>
<p>This is an overloaded intrinsic. You can use <tt>llvm.ssub.with.overflow</tt>
on any integer bit width.</p>
<pre>
declare {i16, i1} @llvm.ssub.with.overflow.i16(i16 %a, i16 %b)
declare {i32, i1} @llvm.ssub.with.overflow.i32(i32 %a, i32 %b)
declare {i64, i1} @llvm.ssub.with.overflow.i64(i64 %a, i64 %b)
</pre>
<h5>Overview:</h5>
<p>The '<tt>llvm.ssub.with.overflow</tt>' family of intrinsic functions perform
a signed subtraction of the two arguments, and indicate whether an overflow
occurred during the signed subtraction.</p>
<h5>Arguments:</h5>
<p>The arguments (%a and %b) and the first element of the result structure may
be of integer types of any bit width, but they must have the same bit
width. The second element of the result structure must be of
type <tt>i1</tt>. <tt>%a</tt> and <tt>%b</tt> are the two values that will
undergo signed subtraction.</p>
<h5>Semantics:</h5>
<p>The '<tt>llvm.ssub.with.overflow</tt>' family of intrinsic functions perform
a signed subtraction of the two arguments. They return a structure —
the first element of which is the subtraction, and the second element of
which is a bit specifying if the signed subtraction resulted in an
overflow.</p>
<h5>Examples:</h5>
<pre>
%res = call {i32, i1} @llvm.ssub.with.overflow.i32(i32 %a, i32 %b)
%sum = extractvalue {i32, i1} %res, 0
%obit = extractvalue {i32, i1} %res, 1
br i1 %obit, label %overflow, label %normal
</pre>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="int_usub_overflow">
'<tt>llvm.usub.with.overflow.*</tt>' Intrinsics
</a>
</h4>
<div>
<h5>Syntax:</h5>
<p>This is an overloaded intrinsic. You can use <tt>llvm.usub.with.overflow</tt>
on any integer bit width.</p>
<pre>
declare {i16, i1} @llvm.usub.with.overflow.i16(i16 %a, i16 %b)
declare {i32, i1} @llvm.usub.with.overflow.i32(i32 %a, i32 %b)
declare {i64, i1} @llvm.usub.with.overflow.i64(i64 %a, i64 %b)
</pre>
<h5>Overview:</h5>
<p>The '<tt>llvm.usub.with.overflow</tt>' family of intrinsic functions perform
an unsigned subtraction of the two arguments, and indicate whether an
overflow occurred during the unsigned subtraction.</p>
<h5>Arguments:</h5>
<p>The arguments (%a and %b) and the first element of the result structure may
be of integer types of any bit width, but they must have the same bit
width. The second element of the result structure must be of
type <tt>i1</tt>. <tt>%a</tt> and <tt>%b</tt> are the two values that will
undergo unsigned subtraction.</p>
<h5>Semantics:</h5>
<p>The '<tt>llvm.usub.with.overflow</tt>' family of intrinsic functions perform
an unsigned subtraction of the two arguments. They return a structure —
the first element of which is the subtraction, and the second element of
which is a bit specifying if the unsigned subtraction resulted in an
overflow.</p>
<h5>Examples:</h5>
<pre>
%res = call {i32, i1} @llvm.usub.with.overflow.i32(i32 %a, i32 %b)
%sum = extractvalue {i32, i1} %res, 0
%obit = extractvalue {i32, i1} %res, 1
br i1 %obit, label %overflow, label %normal
</pre>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="int_smul_overflow">
'<tt>llvm.smul.with.overflow.*</tt>' Intrinsics
</a>
</h4>
<div>
<h5>Syntax:</h5>
<p>This is an overloaded intrinsic. You can use <tt>llvm.smul.with.overflow</tt>
on any integer bit width.</p>
<pre>
declare {i16, i1} @llvm.smul.with.overflow.i16(i16 %a, i16 %b)
declare {i32, i1} @llvm.smul.with.overflow.i32(i32 %a, i32 %b)
declare {i64, i1} @llvm.smul.with.overflow.i64(i64 %a, i64 %b)
</pre>
<h5>Overview:</h5>
<p>The '<tt>llvm.smul.with.overflow</tt>' family of intrinsic functions perform
a signed multiplication of the two arguments, and indicate whether an
overflow occurred during the signed multiplication.</p>
<h5>Arguments:</h5>
<p>The arguments (%a and %b) and the first element of the result structure may
be of integer types of any bit width, but they must have the same bit
width. The second element of the result structure must be of
type <tt>i1</tt>. <tt>%a</tt> and <tt>%b</tt> are the two values that will
undergo signed multiplication.</p>
<h5>Semantics:</h5>
<p>The '<tt>llvm.smul.with.overflow</tt>' family of intrinsic functions perform
a signed multiplication of the two arguments. They return a structure —
the first element of which is the multiplication, and the second element of
which is a bit specifying if the signed multiplication resulted in an
overflow.</p>
<h5>Examples:</h5>
<pre>
%res = call {i32, i1} @llvm.smul.with.overflow.i32(i32 %a, i32 %b)
%sum = extractvalue {i32, i1} %res, 0
%obit = extractvalue {i32, i1} %res, 1
br i1 %obit, label %overflow, label %normal
</pre>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="int_umul_overflow">
'<tt>llvm.umul.with.overflow.*</tt>' Intrinsics
</a>
</h4>
<div>
<h5>Syntax:</h5>
<p>This is an overloaded intrinsic. You can use <tt>llvm.umul.with.overflow</tt>
on any integer bit width.</p>
<pre>
declare {i16, i1} @llvm.umul.with.overflow.i16(i16 %a, i16 %b)
declare {i32, i1} @llvm.umul.with.overflow.i32(i32 %a, i32 %b)
declare {i64, i1} @llvm.umul.with.overflow.i64(i64 %a, i64 %b)
</pre>
<h5>Overview:</h5>
<p>The '<tt>llvm.umul.with.overflow</tt>' family of intrinsic functions perform
a unsigned multiplication of the two arguments, and indicate whether an
overflow occurred during the unsigned multiplication.</p>
<h5>Arguments:</h5>
<p>The arguments (%a and %b) and the first element of the result structure may
be of integer types of any bit width, but they must have the same bit
width. The second element of the result structure must be of
type <tt>i1</tt>. <tt>%a</tt> and <tt>%b</tt> are the two values that will
undergo unsigned multiplication.</p>
<h5>Semantics:</h5>
<p>The '<tt>llvm.umul.with.overflow</tt>' family of intrinsic functions perform
an unsigned multiplication of the two arguments. They return a structure
— the first element of which is the multiplication, and the second
element of which is a bit specifying if the unsigned multiplication resulted
in an overflow.</p>
<h5>Examples:</h5>
<pre>
%res = call {i32, i1} @llvm.umul.with.overflow.i32(i32 %a, i32 %b)
%sum = extractvalue {i32, i1} %res, 0
%obit = extractvalue {i32, i1} %res, 1
br i1 %obit, label %overflow, label %normal
</pre>
</div>
</div>
<!-- ======================================================================= -->
<h3>
<a name="spec_arithmetic">Specialised Arithmetic Intrinsics</a>
</h3>
<!-- _______________________________________________________________________ -->
<h4>
<a name="fmuladd">'<tt>llvm.fmuladd.*</tt>' Intrinsic</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
declare float @llvm.fmuladd.f32(float %a, float %b, float %c)
declare double @llvm.fmuladd.f64(double %a, double %b, double %c)
</pre>
<h5>Overview:</h5>
<p>The '<tt>llvm.fmuladd.*</tt>' intrinsic functions represent multiply-add
expressions that can be fused if the code generator determines that the fused
expression would be legal and efficient.</p>
<h5>Arguments:</h5>
<p>The '<tt>llvm.fmuladd.*</tt>' intrinsics each take three arguments: two
multiplicands, a and b, and an addend c.</p>
<h5>Semantics:</h5>
<p>The expression:</p>
<pre>
%0 = call float @llvm.fmuladd.f32(%a, %b, %c)
</pre>
<p>is equivalent to the expression a * b + c, except that rounding will not be
performed between the multiplication and addition steps if the code generator
fuses the operations. Fusion is not guaranteed, even if the target platform
supports it. If a fused multiply-add is required the corresponding llvm.fma.*
intrinsic function should be used instead.</p>
<h5>Examples:</h5>
<pre>
%r2 = call float @llvm.fmuladd.f32(float %a, float %b, float %c) ; yields {float}:r2 = (a * b) + c
</pre>
</div>
<!-- ======================================================================= -->
<h3>
<a name="int_fp16">Half Precision Floating Point Intrinsics</a>
</h3>
<div>
<p>For most target platforms, half precision floating point is a storage-only
format. This means that it is
a dense encoding (in memory) but does not support computation in the
format.</p>
<p>This means that code must first load the half-precision floating point
value as an i16, then convert it to float with <a
href="#int_convert_from_fp16"><tt>llvm.convert.from.fp16</tt></a>.
Computation can then be performed on the float value (including extending to
double etc). To store the value back to memory, it is first converted to
float if needed, then converted to i16 with
<a href="#int_convert_to_fp16"><tt>llvm.convert.to.fp16</tt></a>, then
storing as an i16 value.</p>
<!-- _______________________________________________________________________ -->
<h4>
<a name="int_convert_to_fp16">
'<tt>llvm.convert.to.fp16</tt>' Intrinsic
</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
declare i16 @llvm.convert.to.fp16(f32 %a)
</pre>
<h5>Overview:</h5>
<p>The '<tt>llvm.convert.to.fp16</tt>' intrinsic function performs
a conversion from single precision floating point format to half precision
floating point format.</p>
<h5>Arguments:</h5>
<p>The intrinsic function contains single argument - the value to be
converted.</p>
<h5>Semantics:</h5>
<p>The '<tt>llvm.convert.to.fp16</tt>' intrinsic function performs
a conversion from single precision floating point format to half precision
floating point format. The return value is an <tt>i16</tt> which
contains the converted number.</p>
<h5>Examples:</h5>
<pre>
%res = call i16 @llvm.convert.to.fp16(f32 %a)
store i16 %res, i16* @x, align 2
</pre>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="int_convert_from_fp16">
'<tt>llvm.convert.from.fp16</tt>' Intrinsic
</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
declare f32 @llvm.convert.from.fp16(i16 %a)
</pre>
<h5>Overview:</h5>
<p>The '<tt>llvm.convert.from.fp16</tt>' intrinsic function performs
a conversion from half precision floating point format to single precision
floating point format.</p>
<h5>Arguments:</h5>
<p>The intrinsic function contains single argument - the value to be
converted.</p>
<h5>Semantics:</h5>
<p>The '<tt>llvm.convert.from.fp16</tt>' intrinsic function performs a
conversion from half single precision floating point format to single
precision floating point format. The input half-float value is represented by
an <tt>i16</tt> value.</p>
<h5>Examples:</h5>
<pre>
%a = load i16* @x, align 2
%res = call f32 @llvm.convert.from.fp16(i16 %a)
</pre>
</div>
</div>
<!-- ======================================================================= -->
<h3>
<a name="int_debugger">Debugger Intrinsics</a>
</h3>
<div>
<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>
<!-- ======================================================================= -->
<h3>
<a name="int_eh">Exception Handling Intrinsics</a>
</h3>
<div>
<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>
<!-- ======================================================================= -->
<h3>
<a name="int_trampoline">Trampoline Intrinsics</a>
</h3>
<div>
<p>These intrinsics make it possible to excise one parameter, marked with
the <a href="#nest"><tt>nest</tt></a> attribute, from a function.
The result is a callable
function pointer lacking the nest parameter - the caller does not need to
provide a value for it. Instead, the value to use is stored in advance in a
"trampoline", a block of memory usually allocated on the stack, which also
contains code to splice the nest value into the argument list. This is used
to implement the GCC nested function address extension.</p>
<p>For example, if the function is
<tt>i32 f(i8* nest %c, i32 %x, i32 %y)</tt> then the resulting function
pointer has signature <tt>i32 (i32, i32)*</tt>. It can be created as
follows:</p>
<pre class="doc_code">
%tramp = alloca [10 x i8], align 4 ; size and alignment only correct for X86
%tramp1 = getelementptr [10 x i8]* %tramp, i32 0, i32 0
call i8* @llvm.init.trampoline(i8* %tramp1, i8* bitcast (i32 (i8*, i32, i32)* @f to i8*), i8* %nval)
%p = call i8* @llvm.adjust.trampoline(i8* %tramp1)
%fp = bitcast i8* %p to i32 (i32, i32)*
</pre>
<p>The call <tt>%val = call i32 %fp(i32 %x, i32 %y)</tt> is then equivalent
to <tt>%val = call i32 %f(i8* %nval, i32 %x, i32 %y)</tt>.</p>
<!-- _______________________________________________________________________ -->
<h4>
<a name="int_it">
'<tt>llvm.init.trampoline</tt>' Intrinsic
</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
declare void @llvm.init.trampoline(i8* <tramp>, i8* <func>, i8* <nval>)
</pre>
<h5>Overview:</h5>
<p>This fills the memory pointed to by <tt>tramp</tt> with executable code,
turning it into a trampoline.</p>
<h5>Arguments:</h5>
<p>The <tt>llvm.init.trampoline</tt> intrinsic takes three arguments, all
pointers. The <tt>tramp</tt> argument must point to a sufficiently large and
sufficiently aligned block of memory; this memory is written to by the
intrinsic. Note that the size and the alignment are target-specific - LLVM
currently provides no portable way of determining them, so a front-end that
generates this intrinsic needs to have some target-specific knowledge.
The <tt>func</tt> argument must hold a function bitcast to
an <tt>i8*</tt>.</p>
<h5>Semantics:</h5>
<p>The block of memory pointed to by <tt>tramp</tt> is filled with target
dependent code, turning it into a function. Then <tt>tramp</tt> needs to be
passed to <a href="#int_at">llvm.adjust.trampoline</a> to get a pointer
which can be <a href="#int_trampoline">bitcast (to a new function) and
called</a>. The new function's signature is the same as that of
<tt>func</tt> with any arguments marked with the <tt>nest</tt> attribute
removed. At most one such <tt>nest</tt> argument is allowed, and it must be of
pointer type. Calling the new function is equivalent to calling <tt>func</tt>
with the same argument list, but with <tt>nval</tt> used for the missing
<tt>nest</tt> argument. If, after calling <tt>llvm.init.trampoline</tt>, the
memory pointed to by <tt>tramp</tt> is modified, then the effect of any later call
to the returned function pointer is undefined.</p>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="int_at">
'<tt>llvm.adjust.trampoline</tt>' Intrinsic
</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
declare i8* @llvm.adjust.trampoline(i8* <tramp>)
</pre>
<h5>Overview:</h5>
<p>This performs any required machine-specific adjustment to the address of a
trampoline (passed as <tt>tramp</tt>).</p>
<h5>Arguments:</h5>
<p><tt>tramp</tt> must point to a block of memory which already has trampoline code
filled in by a previous call to <a href="#int_it"><tt>llvm.init.trampoline</tt>
</a>.</p>
<h5>Semantics:</h5>
<p>On some architectures the address of the code to be executed needs to be
different to the address where the trampoline is actually stored. This
intrinsic returns the executable address corresponding to <tt>tramp</tt>
after performing the required machine specific adjustments.
The pointer returned can then be <a href="#int_trampoline"> bitcast and
executed</a>.
</p>
</div>
</div>
<!-- ======================================================================= -->
<h3>
<a name="int_memorymarkers">Memory Use Markers</a>
</h3>
<div>
<p>This class of intrinsics exists to information about the lifetime of memory
objects and ranges where variables are immutable.</p>
<!-- _______________________________________________________________________ -->
<h4>
<a name="int_lifetime_start">'<tt>llvm.lifetime.start</tt>' Intrinsic</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
declare void @llvm.lifetime.start(i64 <size>, i8* nocapture <ptr>)
</pre>
<h5>Overview:</h5>
<p>The '<tt>llvm.lifetime.start</tt>' intrinsic specifies the start of a memory
object's lifetime.</p>
<h5>Arguments:</h5>
<p>The first argument is a constant integer representing the size of the
object, or -1 if it is variable sized. The second argument is a pointer to
the object.</p>
<h5>Semantics:</h5>
<p>This intrinsic indicates that before this point in the code, the value of the
memory pointed to by <tt>ptr</tt> is dead. This means that it is known to
never be used and has an undefined value. A load from the pointer that
precedes this intrinsic can be replaced with
<tt>'<a href="#undefvalues">undef</a>'</tt>.</p>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="int_lifetime_end">'<tt>llvm.lifetime.end</tt>' Intrinsic</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
declare void @llvm.lifetime.end(i64 <size>, i8* nocapture <ptr>)
</pre>
<h5>Overview:</h5>
<p>The '<tt>llvm.lifetime.end</tt>' intrinsic specifies the end of a memory
object's lifetime.</p>
<h5>Arguments:</h5>
<p>The first argument is a constant integer representing the size of the
object, or -1 if it is variable sized. The second argument is a pointer to
the object.</p>
<h5>Semantics:</h5>
<p>This intrinsic indicates that after this point in the code, the value of the
memory pointed to by <tt>ptr</tt> is dead. This means that it is known to
never be used and has an undefined value. Any stores into the memory object
following this intrinsic may be removed as dead.
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="int_invariant_start">'<tt>llvm.invariant.start</tt>' Intrinsic</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
declare {}* @llvm.invariant.start(i64 <size>, i8* nocapture <ptr>)
</pre>
<h5>Overview:</h5>
<p>The '<tt>llvm.invariant.start</tt>' intrinsic specifies that the contents of
a memory object will not change.</p>
<h5>Arguments:</h5>
<p>The first argument is a constant integer representing the size of the
object, or -1 if it is variable sized. The second argument is a pointer to
the object.</p>
<h5>Semantics:</h5>
<p>This intrinsic indicates that until an <tt>llvm.invariant.end</tt> that uses
the return value, the referenced memory location is constant and
unchanging.</p>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="int_invariant_end">'<tt>llvm.invariant.end</tt>' Intrinsic</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
declare void @llvm.invariant.end({}* <start>, i64 <size>, i8* nocapture <ptr>)
</pre>
<h5>Overview:</h5>
<p>The '<tt>llvm.invariant.end</tt>' intrinsic specifies that the contents of
a memory object are mutable.</p>
<h5>Arguments:</h5>
<p>The first argument is the matching <tt>llvm.invariant.start</tt> intrinsic.
The second argument is a constant integer representing the size of the
object, or -1 if it is variable sized and the third argument is a pointer
to the object.</p>
<h5>Semantics:</h5>
<p>This intrinsic indicates that the memory is mutable again.</p>
</div>
</div>
<!-- ======================================================================= -->
<h3>
<a name="int_general">General Intrinsics</a>
</h3>
<div>
<p>This class of intrinsics is designed to be generic and has no specific
purpose.</p>
<!-- _______________________________________________________________________ -->
<h4>
<a name="int_var_annotation">'<tt>llvm.var.annotation</tt>' Intrinsic</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
declare void @llvm.var.annotation(i8* <val>, i8* <str>, i8* <str>, i32 <int>)
</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.</p>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="int_annotation">'<tt>llvm.annotation.*</tt>' Intrinsic</a>
</h4>
<div>
<h5>Syntax:</h5>
<p>This is an overloaded intrinsic. You can use '<tt>llvm.annotation</tt>' on
any integer bit width.</p>
<pre>
declare i8 @llvm.annotation.i8(i8 <val>, i8* <str>, i8* <str>, i32 <int>)
declare i16 @llvm.annotation.i16(i16 <val>, i8* <str>, i8* <str>, i32 <int>)
declare i32 @llvm.annotation.i32(i32 <val>, i8* <str>, i8* <str>, i32 <int>)
declare i64 @llvm.annotation.i64(i64 <val>, i8* <str>, i8* <str>, i32 <int>)
declare i256 @llvm.annotation.i256(i256 <val>, i8* <str>, i8* <str>, i32 <int>)
</pre>
<h5>Overview:</h5>
<p>The '<tt>llvm.annotation</tt>' intrinsic.</p>
<h5>Arguments:</h5>
<p>The first argument is an integer value (result of some expression), 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. It returns the value of the first argument.</p>
<h5>Semantics:</h5>
<p>This intrinsic allows annotations to be put on arbitrary expressions 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.</p>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="int_trap">'<tt>llvm.trap</tt>' Intrinsic</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
declare void @llvm.trap() noreturn nounwind
</pre>
<h5>Overview:</h5>
<p>The '<tt>llvm.trap</tt>' intrinsic.</p>
<h5>Arguments:</h5>
<p>None.</p>
<h5>Semantics:</h5>
<p>This intrinsic is lowered to the target dependent trap instruction. If the
target does not have a trap instruction, this intrinsic will be lowered to
a call of the <tt>abort()</tt> function.</p>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="int_debugtrap">'<tt>llvm.debugtrap</tt>' Intrinsic</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
declare void @llvm.debugtrap() nounwind
</pre>
<h5>Overview:</h5>
<p>The '<tt>llvm.debugtrap</tt>' intrinsic.</p>
<h5>Arguments:</h5>
<p>None.</p>
<h5>Semantics:</h5>
<p>This intrinsic is lowered to code which is intended to cause an execution
trap with the intention of requesting the attention of a debugger.</p>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="int_stackprotector">'<tt>llvm.stackprotector</tt>' Intrinsic</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
declare void @llvm.stackprotector(i8* <guard>, i8** <slot>)
</pre>
<h5>Overview:</h5>
<p>The <tt>llvm.stackprotector</tt> intrinsic takes the <tt>guard</tt> and
stores it onto the stack at <tt>slot</tt>. The stack slot is adjusted to
ensure that it is placed on the stack before local variables.</p>
<h5>Arguments:</h5>
<p>The <tt>llvm.stackprotector</tt> intrinsic requires two pointer
arguments. The first argument is the value loaded from the stack
guard <tt>@__stack_chk_guard</tt>. The second variable is an <tt>alloca</tt>
that has enough space to hold the value of the guard.</p>
<h5>Semantics:</h5>
<p>This intrinsic causes the prologue/epilogue inserter to force the position of
the <tt>AllocaInst</tt> stack slot to be before local variables on the
stack. This is to ensure that if a local variable on the stack is
overwritten, it will destroy the value of the guard. When the function exits,
the guard on the stack is checked against the original guard. If they are
different, then the program aborts by calling the <tt>__stack_chk_fail()</tt>
function.</p>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="int_objectsize">'<tt>llvm.objectsize</tt>' Intrinsic</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
declare i32 @llvm.objectsize.i32(i8* <object>, i1 <min>)
declare i64 @llvm.objectsize.i64(i8* <object>, i1 <min>)
</pre>
<h5>Overview:</h5>
<p>The <tt>llvm.objectsize</tt> intrinsic is designed to provide information to
the optimizers to determine at compile time whether a) an operation (like
memcpy) will overflow a buffer that corresponds to an object, or b) that a
runtime check for overflow isn't necessary. An object in this context means
an allocation of a specific class, structure, array, or other object.</p>
<h5>Arguments:</h5>
<p>The <tt>llvm.objectsize</tt> intrinsic takes two arguments. The first
argument is a pointer to or into the <tt>object</tt>. The second argument
is a boolean and determines whether <tt>llvm.objectsize</tt> returns 0 (if
true) or -1 (if false) when the object size is unknown.
The second argument only accepts constants.</p>
<h5>Semantics:</h5>
<p>The <tt>llvm.objectsize</tt> intrinsic is lowered to a constant representing
the size of the object concerned. If the size cannot be determined at compile
time, <tt>llvm.objectsize</tt> returns <tt>i32/i64 -1 or 0</tt>
(depending on the <tt>min</tt> argument).</p>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="int_expect">'<tt>llvm.expect</tt>' Intrinsic</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
declare i32 @llvm.expect.i32(i32 <val>, i32 <expected_val>)
declare i64 @llvm.expect.i64(i64 <val>, i64 <expected_val>)
</pre>
<h5>Overview:</h5>
<p>The <tt>llvm.expect</tt> intrinsic provides information about expected (the
most probable) value of <tt>val</tt>, which can be used by optimizers.</p>
<h5>Arguments:</h5>
<p>The <tt>llvm.expect</tt> intrinsic takes two arguments. The first
argument is a value. The second argument is an expected value, this needs to
be a constant value, variables are not allowed.</p>
<h5>Semantics:</h5>
<p>This intrinsic is lowered to the <tt>val</tt>.</p>
</div>
<!-- _______________________________________________________________________ -->
<h4>
<a name="int_donothing">'<tt>llvm.donothing</tt>' Intrinsic</a>
</h4>
<div>
<h5>Syntax:</h5>
<pre>
declare void @llvm.donothing() nounwind readnone
</pre>
<h5>Overview:</h5>
<p>The <tt>llvm.donothing</tt> intrinsic doesn't perform any operation. It's the
only intrinsic that can be called with an invoke instruction.</p>
<h5>Arguments:</h5>
<p>None.</p>
<h5>Semantics:</h5>
<p>This intrinsic does nothing, and it's removed by optimizers and ignored by
codegen.</p>
</div>
</div>
</div>
<!-- *********************************************************************** -->
<hr>
<address>
<a href="http://jigsaw.w3.org/css-validator/check/referer"><img
src="http://jigsaw.w3.org/css-validator/images/vcss-blue" alt="Valid CSS"></a>
<a href="http://validator.w3.org/check/referer"><img
src="http://www.w3.org/Icons/valid-html401-blue" 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>
|
