<html>
    <head>
      <base href="https://bugs.llvm.org/">
    </head>
    <body><table border="1" cellspacing="0" cellpadding="8">
        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - Redundant vmov{q,d} before 32-bit splat"
   href="https://bugs.llvm.org/show_bug.cgi?id=45314">45314</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>Redundant vmov{q,d} before 32-bit splat
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>libraries
          </td>
        </tr>

        <tr>
          <th>Version</th>
          <td>trunk
          </td>
        </tr>

        <tr>
          <th>Hardware</th>
          <td>PC
          </td>
        </tr>

        <tr>
          <th>OS</th>
          <td>Windows NT
          </td>
        </tr>

        <tr>
          <th>Status</th>
          <td>NEW
          </td>
        </tr>

        <tr>
          <th>Severity</th>
          <td>enhancement
          </td>
        </tr>

        <tr>
          <th>Priority</th>
          <td>P
          </td>
        </tr>

        <tr>
          <th>Component</th>
          <td>Backend: X86
          </td>
        </tr>

        <tr>
          <th>Assignee</th>
          <td>unassignedbugs@nondot.org
          </td>
        </tr>

        <tr>
          <th>Reporter</th>
          <td>daan@dsprenkels.com
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>craig.topper@gmail.com, llvm-bugs@lists.llvm.org, llvm-dev@redking.me.uk, spatel+llvm@rotateright.com
          </td>
        </tr></table>
      <p>
        <div>
        <pre>The following code:

```
#include <immintrin.h>

__m256i broadcast(const __m256i x) {
    return _mm256_set_epi32(x[0], x[0], x[0], x[0], x[0], x[0], x[0], x[0]);
}
```

is compiled to:

```
broadcast:                              # @broadcast
        vmovq   rax, xmm0
        vmovd   xmm0, eax
        vpbroadcastd    ymm0, xmm0
        ret
```

These two vmov operations are redundant.

GCC already omits these operations:

```
broadcast:
        vpbroadcastd    ymm0, xmm0
        ret
```

Godbolt link: <a href="https://c.godbolt.org/z/bkVDWj">https://c.godbolt.org/z/bkVDWj</a></pre>
        </div>
      </p>


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