title: How to efficiently perform double/int64 conversions with SSE/AVX?
body: <p>SSE2 has instructions for converting vectors between single-precision floats and 32-bit integers.</p>
  
  <ul>
  <li><code>_mm_cvtps_epi32()</code></li>
  <li><code>_mm_cvtepi32_ps()</code></li>
  </ul>
  
  <p>But there are no equivalents for double-precision and 64-bit integers. In other words, they are missing:</p>
  
  <ul>
  <li><code>_mm_cvtpd_epi64()</code></li>
  <li><code>_mm_cvtepi64_pd()</code></li>
  </ul>
  
  <p>It seems that AVX doesn't have them either.</p>
  
  <p>What is the most efficient way to simulate these intrinsics?</p>