bugs/ultrixcc.c

   1 #include <stdio.h>
   2
   3 /*-
   4  * This is a cc optimiser bug for ultrix 4.3, mips CPU.
   5  * What happens is that the compiler, due to the (a)&7,
   6  * does
   7  * i=a&7;
   8  * i--;
   9  * i*=4;
  10  * Then uses i as the offset into a jump table.
  11  * The problem is that a value of 0 generates an offset of
  12  * 0xfffffffc.
  13  */
  14
  15 main()
  16 {
  17     f(5);
  18     f(0);
  19 }
  20
  21 int f(a)
  22 int a;
  23 {
  24     switch (a & 7) {
  25     case 7:
  26         printf("7\n");
  27     case 6:
  28         printf("6\n");
  29     case 5:
  30         printf("5\n");
  31     case 4:
  32         printf("4\n");
  33     case 3:
  34         printf("3\n");
  35     case 2:
  36         printf("2\n");
  37     case 1:
  38         printf("1\n");
  39 #ifdef FIX_BUG
  40     case 0:
  41         ;
  42 #endif
  43     }
  44 }