title: Call gcc builtin in cython?
body: <p>I want to call the <a href="https://gcc.gnu.org/onlinedocs/gcc-4.1.2/gcc/Other-Builtins.html" rel="nofollow">gcc builtin</a> function <code>__builtin_ffs</code> inside a cython sourcefile (<code>.pyx</code>), e.g. like</p>
  
  <pre><code>cpdef int ffs(long b):
      return __builtin_ffs(b);
  </code></pre>
  
  <p>Is it possible? If so, how?</p>