int sum(int x, int y)               sum:                               
{                                     pushl   %ebp             
  return x + y;                       movl    %esp, %ebp     
}                                     movl    12(%ebp), %eax ; y in %eax
                                      addl    8(%ebp), %eax  ; add  x to %eax
                                      popl    %ebp             
                                      ret                    ; return %eax