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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Slowdown on x86 due to r310260"
href="https://bugs.llvm.org/show_bug.cgi?id=34361">34361</a>
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<th>Summary</th>
<td>Slowdown on x86 due to r310260
</td>
</tr>
<tr>
<th>Product</th>
<td>new-bugs
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>Linux
</td>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Severity</th>
<td>enhancement
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>new bugs
</td>
</tr>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
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</tr>
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<th>Reporter</th>
<td>saher.odeh@intel.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>After the above commit, the compiler now decides to vectorize additional code.
However, in spec2017/525 (avx2-x86_64 Linux), the vectorization of
x264_pixel_satd_8x4() causes a ~12% slow-down - presumably due to heavy use of
port 5 (shuffles?).
the following is the breakdown of the resulting instructions and their count:
Count "Instruction
--------------------
50 "vmovd
32 "vpmovzxdq
32 "vpmovzxbd
32 "movzxw
30 "vpsubq
17 "vpaddq
14 "vpextrd
13 "add
12 "sub
11 "vpinsrd
10 "vpshufd
10 "leal
8 "vpsllq
8 "vpblendd
6 "pushq
6 "popq
5 "vpaddd
4 "leaq
2 "vpxor
2 "vpsrld
2 "vpmulld
2 "vpbroadcastdl
2 "vpand
please let me know if more information is needed.</pre>
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</p>
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