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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 - Can't remove insertelement undef"
   href="https://bugs.llvm.org/show_bug.cgi?id=45481">45481</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>Can't remove insertelement undef
          </td>
        </tr>

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

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

        <tr>
          <th>Hardware</th>
          <td>All
          </td>
        </tr>

        <tr>
          <th>OS</th>
          <td>All
          </td>
        </tr>

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

        <tr>
          <th>Keywords</th>
          <td>miscompilation
          </td>
        </tr>

        <tr>
          <th>Severity</th>
          <td>normal
          </td>
        </tr>

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

        <tr>
          <th>Component</th>
          <td>Scalar Optimizations
          </td>
        </tr>

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

        <tr>
          <th>Reporter</th>
          <td>nunoplopes@sapo.pt
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>lebedev.ri@gmail.com, llvm-bugs@lists.llvm.org, regehr@cs.utah.edu, spatel+llvm@rotateright.com
          </td>
        </tr></table>
      <p>
        <div>
        <pre>Test: Transforms/InstSimplify/insertelement.ll
Summary: We can't remove insertelement undef to a vector, since it may be
replacing a poison value.

define <4 x i32> @PR1286(<4 x i32> %A) {
  %B = insertelement <4 x i32> %A, i32 undef, i32 1
  ret <4 x i32> %B
}
=>
define <4 x i32> @PR1286(<4 x i32> %A) {
  ret <4 x i32> %A
}
Transformation doesn't verify!
ERROR: Target is more poisonous than source

Example:
<4 x i32> %A = < poison, poison, poison, poison >

Source:
<4 x i32> %B = < poison, undef, poison, poison >

Target:
Source value: < poison, undef, poison, poison >
Target value: < poison, poison, poison, poison >


Report:
<a href="https://web.ist.utl.pt/nuno.lopes/alive2/index.php?hash=ed3ac07d4817b221&test=Transforms%2FInstSimplify%2Finsertelement.ll">https://web.ist.utl.pt/nuno.lopes/alive2/index.php?hash=ed3ac07d4817b221&test=Transforms%2FInstSimplify%2Finsertelement.ll</a></pre>
        </div>
      </p>


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