<table border="1" cellspacing="0" cellpadding="8">
    <tr>
        <th>Issue</th>
        <td>
            <a href=https://github.com/llvm/llvm-project/issues/89414>89414</a>
        </td>
    </tr>

    <tr>
        <th>Summary</th>
        <td>
            [DAG] SelectionDAG.computeKnownBits - add NSW/NUW flags support to ISD::SHL handling
        </td>
    </tr>

    <tr>
      <th>Labels</th>
      <td>
            good first issue,
            llvm:SelectionDAG
      </td>
    </tr>

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

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

<pre>
    The call to KnownBits::shl is currently not handling nodes that have the NSW/NUW flags (or a known non zero shift amount).

https://github.com/llvm/llvm-project/blob/e553ac4d8148291914526f4f66f09e362ce0a63f/llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp#L3497-L3506

This task will mainly involve adding test coverage - my advice would be to disable the equivalent handling in ValueTracking, run `check-llvm-transforms` to see what tests start failing and see what equivalent tests can be created for CodeGen/X86

https://github.com/llvm/llvm-project/blob/e553ac4d8148291914526f4f66f09e362ce0a63f/llvm/lib/Analysis/ValueTracking.cpp#L1168-L1182
</pre>
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