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<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>
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<th>Summary</th>
<td>[AVX2] Cannot select: v8i32 = X86ISD::VZEXT with old vector shuffle lowering
</td>
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<th>Product</th>
<td>libraries
</td>
</tr>
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<th>Version</th>
<td>trunk
</td>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>All
</td>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>normal
</td>
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>Backend: X86
</td>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>qcolombet@apple.com
</td>
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<th>CC</th>
<td>llvmbugs@cs.uiuc.edu
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<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>
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