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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - EarlyCSE MemorySSA breaks vpx_idct32x32_1024_add_neon from libvpx when targeting armv7"
href="https://bugs.llvm.org/show_bug.cgi?id=36883">36883</a>
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<th>Summary</th>
<td>EarlyCSE MemorySSA breaks vpx_idct32x32_1024_add_neon from libvpx when targeting armv7
</td>
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<th>Product</th>
<td>libraries
</td>
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<th>Version</th>
<td>5.0
</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>enhancement
</td>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>Scalar Optimizations
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
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<th>Reporter</th>
<td>martin@martin.st
</td>
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<th>CC</th>
<td>llvm-bugs@lists.llvm.org
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<p>
<div>
<pre>Since SVN r306477 of LLVM ([EarlyCSE][MemorySSA] Enable MemorySSA in
function-simplification pass of EarlyCSE.; present in the 5.0 and 6.0
releases), the vpx_idct32x32_1024_add_neon (intrinsics based) function of
libvpx gets broken/misoptimized. Not yet sure if this is an LLVM bug or some
other wrong with the function that allows the optimizer to break it.
To work around the issue, one can build with "-mllvm
-enable-npm-earlycse-memssa=false -mllvm -enable-earlycse-memssa=false".
The same issue is reported for libvpx at
<a href="https://bugs.chromium.org/p/webm/issues/detail?id=1510">https://bugs.chromium.org/p/webm/issues/detail?id=1510</a>.</pre>
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