1/* NOCW */
2/* sgibug.c */
3/* bug found by Eric Young (eay@mincom.oz.au) May 95 */
4
5#include <stdio.h>
6
7/*
8 * This compiler bug it present on IRIX 5.3, 5.1 and 4.0.5 (these are the
9 * only versions of IRIX I have access to. defining FIXBUG removes the bug.
10 * (bug is still present in IRIX 6.3 according to Gage
11 * <agage@forgetmenot.Mines.EDU>
12 */
13
14/*-
15 * Compare the output from
16 * cc sgiccbug.c; ./a.out
17 * and
18 * cc -O sgiccbug.c; ./a.out
19 */
20
21static unsigned long a[4] =
22    { 0x01234567, 0x89ABCDEF, 0xFEDCBA98, 0x76543210 };
23static unsigned long b[4] =
24    { 0x89ABCDEF, 0xFEDCBA98, 0x76543210, 0x01234567 };
25static unsigned long c[4] =
26    { 0x77777778, 0x8ACF1357, 0x88888888, 0x7530ECA9 };
27
28main()
29{
30    unsigned long r[4];
31    sub(r, a, b);
32    fprintf(stderr, "input a= %08X %08X %08X %08X\n", a[3], a[2], a[1], a[0]);
33    fprintf(stderr, "input b= %08X %08X %08X %08X\n", b[3], b[2], b[1], b[0]);
34    fprintf(stderr, "output = %08X %08X %08X %08X\n", r[3], r[2], r[1], r[0]);
35    fprintf(stderr, "correct= %08X %08X %08X %08X\n", c[3], c[2], c[1], c[0]);
36}
37
38int sub(r, a, b)
39unsigned long *r, *a, *b;
40{
41    register unsigned long t1, t2, *ap, *bp, *rp;
42    int i, carry;
43#ifdef FIXBUG
44    unsigned long dummy;
45#endif
46
47    ap = a;
48    bp = b;
49    rp = r;
50    carry = 0;
51    for (i = 0; i < 4; i++) {
52        t1 = *(ap++);
53        t2 = *(bp++);
54        t1 = (t1 - t2);
55#ifdef FIXBUG
56        dummy = t1;
57#endif
58        *(rp++) = t1 & 0xffffffff;
59    }
60}
61