title: What does "code motion" mean for "loop-invariant code motion"?
body: <p>In compilers, the phrase <a href="http://en.wikipedia.org/wiki/Loop-invariant_code_motion" rel="noreferrer">"loop-invariant code motion"</a> describes expressions or statements of code in a loop that don't change from iteration to iteration and hence can be moved outside of the loop to be computed once.  </p>
  
  <p>I understand the "loop-invariant" piece of the phrase, but what does the "code motion" mean?</p>