title: How to merge elements of 2 rows using NEON SIMD?
body: <p>I have a </p>
  
  <pre><code>A = a1 a2 a3 a4
      b1 b2 b3 b4
      c1 c2 c3 c4
      d1 d2 d3 d4
  </code></pre>
  
  <p>I have 2 rows with me,</p>
  
  <pre><code>float32x2_t a = a1 a2
  float32x2_t b = b1 b2
  </code></pre>
  
  <p>From these how can I get a -</p>
  
  <pre><code>float32x4_t result = b1 a1 b2 a2
  </code></pre>
  
  <p>Is there any <strong>single NEON SIMD instruction</strong> which can merge these two rows?
  Or how can I achieve this using as minimum steps as possible using intrinsics?</p>
  
  <p>I thought of using the <strong>zip/unzip</strong> intrinsics but the datatype the <strong>zip function</strong> returns, which is <code>float32x2x2_t</code>, is not suitable for me, I need a <code>float32x4_t</code> datatype.</p>
  
  <pre><code>float32x2x2_t vzip_f32 (float32x2_t, float32x2_t)
  </code></pre>