20020716-1.c

this is a gcc file, you can download it and learn its usetility, for further detail please look at t

extern void abort (void);
extern void exit (int);

int sub1 (int val)
{
  return val;
}

int testcond (int val)
{
  int flag1;

    {
      int t1 = val;
        {
          int t2 = t1;
            {
              flag1 = sub1 (t2) ==0;
              goto lab1;
            };
        }
      lab1: ;
    }

  if (flag1 != 0)
    return 0x4d0000;
  else
    return 0;
}

int main (void)
{
  if (testcond (1))
    abort ();
  exit (0);
}