title: How does a modern compiler go about optimizing this code
body: <p>How would a modern compiler optimize this code:</p>
  <pre><code>int fn (int a, int b)
  {
      int sum = 0;
      for(int i=4*a; i&gt;0; i--)
      {
          sum += b*i*i;
      }
      return sum;
  }
  </code></pre>