bugs/sgiccbug.c

   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  */
  11
  12 /* Compare the output from
  13  * cc sgiccbug.c; ./a.out
  14  * and
  15  * cc -O sgiccbug.c; ./a.out
  16  */
  17
  18 static unsigned long a[4]={0x01234567,0x89ABCDEF,0xFEDCBA98,0x76543210};
  19 static unsigned long b[4]={0x89ABCDEF,0xFEDCBA98,0x76543210,0x01234567};
  20 static unsigned long c[4]={0x77777778,0x8ACF1357,0x88888888,0x7530ECA9};
  21
  22 main()
  23         {
  24         unsigned long r[4];
  25         sub(r,a,b);
  26         fprintf(stderr,"input a= %08X %08X %08X %08X\n",a[3],a[2],a[1],a[0]);
  27         fprintf(stderr,"input b= %08X %08X %08X %08X\n",b[3],b[2],b[1],b[0]);
  28         fprintf(stderr,"output = %08X %08X %08X %08X\n",r[3],r[2],r[1],r[0]);
  29         fprintf(stderr,"correct= %08X %08X %08X %08X\n",c[3],c[2],c[1],c[0]);
  30         }
  31
  32 int sub(r,a,b)
  33 unsigned long *r,*a,*b;
  34         {
  35         register unsigned long t1,t2,*ap,*bp,*rp;
  36         int i,carry;
  37 #ifdef FIXBUG
  38         unsigned long dummy;
  39 #endif
  40
  41         ap=a;
  42         bp=b;
  43         rp=r;
  44         carry=0;
  45         for (i=0; i<4; i++)
  46                 {
  47                 t1= *(ap++);
  48                 t2= *(bp++);
  49                 t1=(t1-t2);
  50 #ifdef FIXBUG
  51                 dummy=t1;
  52 #endif
  53                 *(rp++)=t1&0xffffffff;
  54                 }
  55         }