title: How to add 3 large integers efficiently using GMP
body: <p>I want to do x = a + b + c on ~2048 bit signed integers. Currently my code looks like</p>
  
  <pre><code>mpz_add(x, a, b);
  mpz_add(x, x, c);
  </code></pre>
  
  <p>Is there a single function to do this? This happens many many times in my application. I have profiled my code and the 3-way add step is taking up a significant portion of the runtime. If there's an alternative way to do this in a single pass that might help.</p>