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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - AVX-512: Horizontal add pattern match does not work on <16 x i32> vectors"
href="https://bugs.llvm.org/show_bug.cgi?id=33758">33758</a>
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<th>Summary</th>
<td>AVX-512: Horizontal add pattern match does not work on <16 x i32> vectors
</td>
</tr>
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<th>Product</th>
<td>libraries
</td>
</tr>
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<th>Version</th>
<td>trunk
</td>
</tr>
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<th>Hardware</th>
<td>PC
</td>
</tr>
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<th>OS</th>
<td>Windows NT
</td>
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<th>Status</th>
<td>NEW
</td>
</tr>
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<th>Severity</th>
<td>enhancement
</td>
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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
</td>
</tr>
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<th>Reporter</th>
<td>elena.demikhovsky@intel.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
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<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=18782" name="attach_18782" title="Hadd example for <8 x i32> and <16 x i32> cases">attachment 18782</a> <a href="attachment.cgi?id=18782&action=edit" title="Hadd example for <8 x i32> and <16 x i32> cases">[details]</a></span>
Hadd example for <8 x i32> and <16 x i32> cases
The phadd instruction is not chosen from <16 x i32> shuffles+add combination.
This affects reduction tail code.
The same pattern generates better sequence on <8 x i32> code and on AVX2
target.
vpshufd $238, %zmm0, %zmm1
vpaddd %zmm1, %zmm0, %zmm0
vpshufd $229, %zmm0, %zmm1
vpaddd %zmm1, %zmm0, %zmm0
vmovd %xmm0, %eax
better sequence:
vpshufd $238, %zmm0, %zmm1
vpaddd %zmm1, %zmm0, %zmm0
vphadd %zmm0, %zmm0, %zmm0
vmovd %xmm0, %eax
run llc -skx < hadd.ll to reproduce</pre>
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