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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 --- - Failing to vector constant fold vXi64 on 32-bit targets"
href="https://llvm.org/bugs/show_bug.cgi?id=30760">30760</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>Failing to vector constant fold vXi64 on 32-bit targets
</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>
<tr>
<th>OS</th>
<td>Windows NT
</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>llvm-dev@redking.me.uk
</td>
</tr>
<tr>
<th>CC</th>
<td>llvm-bugs@lists.llvm.org, spatel+llvm@rotateright.com
</td>
</tr>
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<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>We are failing to constant fold when have the opportunity because we are
perhaps too strict with only folding to legal scalar types.
e.g.
define <2 x i64> @foldv2i64() nounwind {
%out = call <2 x i64> @llvm.cttz.v2i64(<2 x i64> <i64 256, i64 -1>, i1 0)
ret <2 x i64> %out
}
This works fine for 64-bit targets:
llc < %s -mtriple=x86_64-unknown-unknown -mattr=+sse4.1
foldv2i64:
# BB#0:
movl $8, %eax
movd %rax, %xmm0
retq
But for 32-bit targets we fail to fold as although v2i64 is legal, i64 isn't:
llc < %s -mtriple=i686-unknown-unknown -mattr=+sse4.1
foldv2i64:
# BB#0:
movdqa {{.*#+}} xmm0 = [256,0,4294967295,4294967295]
pxor %xmm1, %xmm1
pxor %xmm2, %xmm2
psubq %xmm0, %xmm2
pand %xmm0, %xmm2
psubq {{\.LCPI.*}}, %xmm2
movdqa {{.*#+}} xmm3 = [15,15,15,15,15,15,15,15,15,15,15,15,15,15,15,15]
movdqa %xmm2, %xmm4
pand %xmm3, %xmm4
movdqa {{.*#+}} xmm0 = [0,1,1,2,1,2,2,3,1,2,2,3,2,3,3,4]
movdqa %xmm0, %xmm5
pshufb %xmm4, %xmm5
psrlw $4, %xmm2
pand %xmm3, %xmm2
pshufb %xmm2, %xmm0
paddb %xmm5, %xmm0
psadbw %xmm1, %xmm0
retl</pre>
</div>
</p>
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