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      <base href="https://bugs.llvm.org/">
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    <body><table border="1" cellspacing="0" cellpadding="8">
        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - [SelectionDAG] Rename/refactor isBuildVectorAllZeros isBuildVectorAllOnes to make undef handling more obvious"
   href="https://bugs.llvm.org/show_bug.cgi?id=43177">43177</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>[SelectionDAG] Rename/refactor isBuildVectorAllZeros isBuildVectorAllOnes to make undef handling more obvious
          </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>Common Code Generator Code
          </td>
        </tr>

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

        <tr>
          <th>Reporter</th>
          <td>llvm-dev@redking.me.uk
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>craig.topper@gmail.com, lebedev.ri@gmail.com, llvm-bugs@lists.llvm.org, spatel+llvm@rotateright.com
          </td>
        </tr></table>
      <p>
        <div>
        <pre>We keep hitting issues with people not realising that these predicates can
contain some (but not all) elements that are undef. e.g. [<a class="bz_bug_link 
          bz_status_RESOLVED  bz_closed"
   title="RESOLVED FIXED - Bug in TargetLowering::SimplifyDemandedBits causing miscompile"
   href="show_bug.cgi?id=43159">Bug #43159</a>]

These keep getting used in patterns like:

// fold (mul x, 0) -> 0
if (ISD::isBuildVectorAllZeros(N0.getNode())
  return N0;

Should we rename these to isBuildVectorAllZerosOrUndefs or similar? Or is there
something else we can do to help avoid this?</pre>
        </div>
      </p>


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