title: How many GCC optimization levels are there?
body: <p>How many <a href="http://en.wikipedia.org/wiki/GNU_Compiler_Collection" rel="noreferrer">GCC</a> optimization levels are there?</p>
  
  <p>I tried gcc -O1, gcc -O2, gcc -O3, and gcc -O4</p>
  
  <p>If I use a really large number, it won't work.</p>
  
  <p>However, I have tried</p>
  
  <pre><code>gcc -O100
  </code></pre>
  
  <p>and it compiled.</p>
  
  <p>How many optimization levels are there?</p>