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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 --- - [X86] Failure to fold v8i16 extractelement 0'th element to (v)pextrw"
href="https://llvm.org/bugs/show_bug.cgi?id=27265">27265</a>
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<th>Summary</th>
<td>[X86] Failure to fold v8i16 extractelement 0'th element to (v)pextrw
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</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>Windows NT
</td>
</tr>
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<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
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<th>Priority</th>
<td>P
</td>
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<th>Component</th>
<td>Backend: X86
</td>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
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<th>Reporter</th>
<td>llvm-dev@redking.me.uk
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>Attempting to store the 0'th element of a v8i16 fails to fold the store:
define void @str0_8i16(<8 x i16> %v, i16* %p) {
%1 = extractelement <8 x i16> %v, i32 0
store i16 %1, i16* %p
ret void
}
llc -march=btver2:
str0_8i16:
vmovd %xmm0, %eax
movw %ax, (%rdi)
retq
Storing other elements works fine:
define void @str1_8i16(<8 x i16> %v, i16* %p) {
%1 = extractelement <8 x i16> %v, i32 1
store i16 %1, i16* %p
ret void
}
llc -march=btver2:
str1_8i16:
vpextrw $1, %xmm0, (%rdi)
retq
And other types (4i32 / 16i8) don't exhibit this.</pre>
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