title: What are GCC’s expensive optimizations?
body: <p><a href="http://gcc.gnu.org/onlinedocs/gcc/Optimize-Options.html" rel="noreferrer">GCC documentation</a> is not particularly verbose about it. What it says is:</p>
  
  <blockquote>
    <p>-fexpensive-optimizations:</p>
  
  <pre><code>     Perform a number of minor optimizations that are relatively expensive.
  </code></pre>
  </blockquote>
  
  <p>Which kind of optimizations are these? Any example?</p>