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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Non-vectorised code slower on ARM"
href="https://llvm.org/bugs/show_bug.cgi?id=26881">26881</a>
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<th>Summary</th>
<td>Non-vectorised code slower on ARM
</td>
</tr>
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<th>Product</th>
<td>libraries
</td>
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<th>Version</th>
<td>3.8
</td>
</tr>
<tr>
<th>Hardware</th>
<td>Other
</td>
</tr>
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<th>OS</th>
<td>Linux
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>Backend: ARM
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
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<th>Reporter</th>
<td>tulipawn@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>So I thought I'd see how well code from issue #26837 was doing on ARM and
here's the result on Cortex-A5:
running 2 tests
wo/NEON
test folds1 ... bench: 3,107 ns/iter (+/- 59)
test folds2 ... bench: 2,490 ns/iter (+/- 34)
w/NEON
test folds1 ... bench: 1,293 ns/iter (+/- 25)
test folds2 ... bench: 2,493 ns/iter (+/- 28)
Judging from those x86 results, there should be no difference between the two
versions in the absence of vector instructions' availability and yet the first
ARM result seems inverted. Probably shouldn't happen.
Flags used:
-C target-cpu=cortex-a5 -C target-feature=+vfp4,-neon -C
llvm-args=-force-target-max-vector-interleave=4</pre>
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