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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - [X86] Missed opportunities to use vcvtdq2pd %xmm0, %xmm0 under AVX"
href="https://bugs.llvm.org/show_bug.cgi?id=36761">36761</a>
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<th>Summary</th>
<td>[X86] Missed opportunities to use vcvtdq2pd %xmm0, %xmm0 under AVX
</td>
</tr>
<tr>
<th>Product</th>
<td>libraries
</td>
</tr>
<tr>
<th>Version</th>
<td>trunk
</td>
</tr>
<tr>
<th>Hardware</th>
<td>PC
</td>
</tr>
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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>enhancement
</td>
</tr>
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<th>Priority</th>
<td>P
</td>
</tr>
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<th>Component</th>
<td>Backend: X86
</td>
</tr>
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<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>craig.topper@gmail.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr></table>
<p>
<div>
<pre>For this IR under AVX, we should be able to use "vcvtdq2pd %xmm0, %xmm0".
define <2 x double> @sitofp_4i32_to_2f64(<4 x i32> %a) {
; SSE-LABEL: sitofp_4i32_to_2f64:
; SSE: # %bb.0:
; SSE-NEXT: cvtdq2pd %xmm0, %xmm0
; SSE-NEXT: retq
;
; AVX-LABEL: sitofp_4i32_to_2f64:
; AVX: # %bb.0:
; AVX-NEXT: vcvtdq2pd %xmm0, %ymm0
; AVX-NEXT: # kill: def $xmm0 killed $xmm0 killed $ymm0
; AVX-NEXT: vzeroupper
; AVX-NEXT: retq
%cvt = sitofp <4 x i32> %a to <4 x double>
%shuf = shufflevector <4 x double> %cvt, <4 x double> undef, <2 x i32> <i32
0, i32 1>
ret <2 x double> %shuf
}
We probably need a DAG combine to merge the extract_subvector we get from the
shuffle.</pre>
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