<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/155390>155390</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [Clang] VectorExprEvaluator::VisitCallExpr - add MMX/SSE/AVX/AVX512 AVG intrinsics to be used in constexpr
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            good first issue,
            backend:X86,
            clang:frontend,
            constexpr
      </td>
    </tr>

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

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

<pre>
    The PAVGB/PAVGW intrinsics can all be used in constexpr with suitable handling of the __builtin_ia32_pavg builtins inside VectorExprEvaluator::VisitCallExpr similar to #152540
```
_mm_avg_pu8
_mm_avg_epu8 _mm256_avg_epu8 _mm512_avg_epu8
_mm_mask_avg_epu8 _mm256_mask_avg_epu8 _mm512_mask_avg_epu8
_mm_maskz_avg_epu8 _mm256_maskz_avg_epu8 _mm512_maskz_avg_epu8

_mm_avg_pu16
_mm_avg_epu16 _mm256_avg_epu16 _mm512_avg_epu16
_mm_mask_avg_epu16 _mm256_mask_avg_epu16 _mm512_mask_avg_epu16
_mm_maskz_avg_epu16 _mm256_maskz_avg_epu16 _mm512_maskz_avg_epu16
```
These all just need to call APIntOps::avgCeilU - and the builtin types should probably be converted to unsigned.
</pre>
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