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