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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - [X86] getFauxShuffleMask generates nodes on the fly"
href="https://bugs.llvm.org/show_bug.cgi?id=45974">45974</a>
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<th>Summary</th>
<td>[X86] getFauxShuffleMask generates nodes on the fly
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<th>Product</th>
<td>libraries
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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>Windows NT
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<th>Status</th>
<td>NEW
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<th>Severity</th>
<td>enhancement
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<th>Priority</th>
<td>P
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<th>Component</th>
<td>Backend: X86
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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<th>Reporter</th>
<td>llvm-dev@redking.me.uk
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<th>CC</th>
<td>craig.topper@gmail.com, llvm-bugs@lists.llvm.org, llvm-dev@redking.me.uk, spatel+llvm@rotateright.com
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<pre>getFauxShuffleMask creates DAG nodes on the fly to help shuffle combines by
trying to return shuffle sources with the same width as the result+mask.
This causes a lot of issues with combines relying on hasOneUse tests (e.g.
SimplifyDemandedBits, load combining etc.), so really we need the shuffle
combiner to be able to handle shuffles with irregular sources so that can
remove all the DAG.getNode() from getFauxShuffleMask.
This might mean that we can remove combineX86ShuffleChainWithExtract as well.</pre>
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