title: Which way is better to get lower 32 bits of a 64 bits integer
body: <p>I found that in some answers they recommended using </p>
  
  <p><code>lower = (some_var &lt;&lt; 32) &gt;&gt; 32;</code></p>
  
  <p>But I tested and found the following is faster:</p>
  
  <p><code>lower = some_var &amp; 0xffffffff;</code></p>
  
  <p>So which is better? Is the former safer in some cases or faster after compiler optimized?</p>