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<base href="https://llvm.org/bugs/" />
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<body><table border="1" cellspacing="0" cellpadding="8">
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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - [x86, SSE] recognize that pcmp produces bitmask results"
href="https://llvm.org/bugs/show_bug.cgi?id=28484">28484</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>[x86, SSE] recognize that pcmp produces bitmask results
</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>All
</td>
</tr>
<tr>
<th>Status</th>
<td>NEW
</td>
</tr>
<tr>
<th>Severity</th>
<td>normal
</td>
</tr>
<tr>
<th>Priority</th>
<td>P
</td>
</tr>
<tr>
<th>Component</th>
<td>Backend: X86
</td>
</tr>
<tr>
<th>Assignee</th>
<td>unassignedbugs@nondot.org
</td>
</tr>
<tr>
<th>Reporter</th>
<td>spatel+llvm@rotateright.com
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org
</td>
</tr>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>define <4 x i32> @foo(<4 x i32> %a, <4 x i32> %b) {
%cmp = icmp eq <4 x i32> %a, %b
%zext = zext <4 x i1> %cmp to <4 x i32> ; "wrong" extend for SSE
ret <4 x i32> %zext
}
$ ./llc -o - boolvec2.ll
LCPI2_0:
.long 1 ## 0x1
.long 1 ## 0x1
.long 1 ## 0x1
.long 1 ## 0x1
...
pcmpeqd %xmm1, %xmm0
pand LCPI2_0(%rip), %xmm0 <--- load + logic
retq
----------------------------------------------------------------------------
Instead of and'ing, we could shift right logical (psrld 31, %xmm0) and not need
to load the constant.</pre>
</div>
</p>
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