When attaching to the following program you cannot print out i or j. Removing
the volatile attribute makes them visable.

#include <stdio.h>

static volatile int i;
static volatile int j;
int
main (int argc, char *argv)
{
  i = 0;
  printf("hello world\n");
  while(1)
    {
      i++;
      j = i;
      j -= 1;
    }
}