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      <base href="http://llvm.org/bugs/" />
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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 --- - [AVX2] Cannot select: v8i32 = X86ISD::VZEXT with old vector shuffle lowering"
   href="http://llvm.org/bugs/show_bug.cgi?id=21876">21876</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>[AVX2] Cannot select: v8i32 = X86ISD::VZEXT with old vector shuffle lowering
          </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>All
          </td>
        </tr>

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

        <tr>
          <th>Severity</th>
          <td>normal
          </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>qcolombet@apple.com
          </td>
        </tr>

        <tr>
          <th>CC</th>
          <td>llvmbugs@cs.uiuc.edu
          </td>
        </tr>

        <tr>
          <th>Classification</th>
          <td>Unclassified
          </td>
        </tr></table>
      <p>
        <div>
        <pre>Created <span class=""><a href="attachment.cgi?id=13515" name="attach_13515" title="IR to reproduce the problem.">attachment 13515</a> <a href="attachment.cgi?id=13515&action=edit" title="IR to reproduce the problem.">[details]</a></span>
IR to reproduce the problem.

While trying to compare the performance of the old vector shuffle lowering
against the new one, I ran into this cannot select error.
This used to work until fairly recently, I think, r223304, but it is now broken
with r223979.

To reproduce:
llc -mtriple=x86_64-apple-macosx
-x86-experimental-vector-shuffle-lowering=false  -mattr=+avx2 tmp3.ll

Removing avx2 or using the new vector shuffle lowering works.

Until the old vector shuffle lowering is official dead, we should fix that to
ease comparison.</pre>
        </div>
      </p>
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