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<base href="https://llvm.org/bugs/" />
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - [AVX-512] LLC Turns "fpext" and "fpmul" into a wrong splitting and addition."
href="https://llvm.org/bugs/show_bug.cgi?id=25289">25289</a>
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<th>Summary</th>
<td>[AVX-512] LLC Turns "fpext" and "fpmul" into a wrong splitting and addition.
</td>
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<th>Product</th>
<td>tools
</td>
</tr>
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<th>Version</th>
<td>trunk
</td>
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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>
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<th>Severity</th>
<td>normal
</td>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>llc
</td>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
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<th>Reporter</th>
<td>shishpanov2010@yandex.ru
</td>
</tr>
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<th>CC</th>
<td>llvm-bugs@lists.llvm.org
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>Created <span class=""><a href="attachment.cgi?id=15144" name="attach_15144" title="The IR sample.">attachment 15144</a> <a href="attachment.cgi?id=15144&action=edit" title="The IR sample.">[details]</a></span>
The IR sample.
LLC tries to extend each of two parts of "%ptr_masked_load.16" in the attached
file. It takes the first half of this vector twice, but, I guess, it should
take two different halves of this vector. For example, the assembly code, what
is the result of LLC:
f_f: # @f_f
vmovups (%rsi), %zmm0
vcvtps2pd %ymm0, %zmm1
vextractf64x4 $2, %zmm0, %ymm0
vcvtps2pd %ymm0, %zmm0
vaddpd %zmm0, %zmm0, %zmm2
vaddpd %zmm1, %zmm1, %zmm3
vmaxpd %zmm3, %zmm1, %zmm1
vmaxpd %zmm2, %zmm0, %zmm0
vcvtpd2ps %zmm1, %ymm1
vcvtpd2ps %zmm0, %ymm0
vinsertf64x4 $1, %ymm0, %zmm1, %zmm0
vmovups %zmm0, (%rdi)
retq
I think, the "vextractf64x4" takes the wrong half of %zmm0.
key for LLC launch: -mcpu=knl</pre>
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