<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/86068>86068</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            missed fold, shuffle(shuffle(v1, m0), v2, m1) => shuffle(v1, v2, m2)
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            missed-optimization
      </td>
    </tr>

    <tr>
      <th>Assignees</th>
      <td>
      </td>
    </tr>

    <tr>
      <th>Reporter</th>
      <td>
          zhengyang92
      </td>
    </tr>
</table>

<pre>
    https://alive2.llvm.org/ce/z/4BPEz9
https://godbolt.org/z/qExEGvbfn (see the subpar codegen)

```
define <2 x float> @src(<2 x float> %0, <2 x float> %1) {
entry:
  %3 = shufflevector <2 x float> %1, <2 x float> poison, <2 x i32> <i32 1, i32 poison>
  %4 = shufflevector <2 x float> %3, <2 x float> %0, <2 x i32> <i32 0, i32 3>
  ret <2 x float> %4

}
define <2 x float> @tgt(<2 x float> %0, <2 x float> %1) {
entry:
  %sv = shufflevector <2 x float> %0, <2 x float> %1, <2 x i32> <i32 3, i32 1>
  ret <2 x float> %sv

}
```
@regehr @dtcxzyw @nikic @efriedma-quic @RKSimon @topperc 


</pre>
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