zation ()
             (labels ((sum-aux (acc x)
                        (if (zerop x)
                            acc
                            (sum-aux (+ acc x) (- x 1))))
                      (sum (n)
                        (sum-aux 0 n)))
               (sum 1000000)))
500000500000 (39 bits, #x746A5A2920)</code></pre><p>This macro gets expanded into:</p>
<pre><code class='lisp'>(let ()
  (declare (optimize (speed 3)))
  (labels ((sum-aux (acc x)
             (if (zerop x)
                 acc
     