1  int b=1;
       2  int foo()
       3  {
       4    int a;
       5    int c;
       6    a=0xff;
       7    for (;b;b--)
       8    {
       9      c=1;
      10      asm(""::"r"(c));
      11      c=(signed char)a;
      12    }
      13    if (c!=-1)
      14      abort();
      15    return c;
      16  }
      17  int main()
      18  {
      19    foo();
      20    return 0;
      21  }