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<base href="https://bugs.llvm.org/">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - AVX-512: Extractelement is not optimal for i1 vectors"
href="https://bugs.llvm.org/show_bug.cgi?id=33692">33692</a>
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<th>Summary</th>
<td>AVX-512: Extractelement is not optimal for i1 vectors
</td>
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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>
</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>elena.demikhovsky@intel.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
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<p>
<div>
<pre>operation extractelement <16 x i1> %vec, i32 const // Not only 16
can generate more optimal code:
; This code in loop preheader
%v_mask = icmp slt <16 x i32> %a, %b
; This code inside the loop vector body
%s_mask = extractelement <16 x i1> %v_mask, i32 5
br i1 %s_mask, label %pred.if, label %pred.continue
pred.if:
..
pred.continue:
vpcmpgtd %zmm0, %zmm1, %k0
#The instructions bellow are inside the loop body
kshiftlw $10, %k0, %k0
kshiftrw $15, %k0, %k0
kmovd %k0, %eax
testb $1, %al
je .LBB0_2
More optimal code:
vpcmpgtd %zmm0, %zmm1, %k0
vpmovm2b %k0, %xmm2
#The instructions bellow will be inside the loop body
vpextrb %xmm2, %eax
testb $1, %al
je .LBB0_2</pre>
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