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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - Improve NEON autovectorization?"
href="https://llvm.org/bugs/show_bug.cgi?id=27103">27103</a>
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<tr>
<th>Summary</th>
<td>Improve NEON autovectorization?
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
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<th>Version</th>
<td>3.8
</td>
</tr>
<tr>
<th>Hardware</th>
<td>Other
</td>
</tr>
<tr>
<th>OS</th>
<td>Linux
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<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>
<tr>
<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=16107" name="attach_16107" title="VFP assembly">attachment 16107</a> <a href="attachment.cgi?id=16107&action=edit" title="VFP assembly">[details]</a></span>
VFP assembly
Benchmarking matrix multiplication Rust code
(<a href="https://github.com/bluss/matrixmultiply/">https://github.com/bluss/matrixmultiply/</a>), we find that on Cortex-A5:
Using VFP:
test mat_mul_f32::m004 ... bench: 1,632 ns/iter (+/- 51)
test mat_mul_f32::m007 ... bench: 3,767 ns/iter (+/- 56)
test mat_mul_f32::m008 ... bench: 4,151 ns/iter (+/- 96)
test mat_mul_f32::m012 ... bench: 8,712 ns/iter (+/- 408)
Using NEON:
test mat_mul_f32::m004 ... bench: 1,588 ns/iter (+/- 89)
test mat_mul_f32::m007 ... bench: 3,307 ns/iter (+/- 94)
test mat_mul_f32::m008 ... bench: 3,056 ns/iter (+/- 62)
test mat_mul_f32::m012 ... bench: 6,197 ns/iter (+/- 181)
Starting with m>=16 the speedup finally reaches 2x. Is there room for
improvement here?</pre>
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