<html>
<head>
<base href="https://llvm.org/bugs/" />
</head>
<body><table border="1" cellspacing="0" cellpadding="8">
<tr>
<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW --- - [X86] recognize vperm2 with zero masks"
href="https://llvm.org/bugs/show_bug.cgi?id=22984">22984</a>
</td>
</tr>
<tr>
<th>Summary</th>
<td>[X86] recognize vperm2 with zero masks
</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>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>llvmbugs@cs.uiuc.edu
</td>
</tr>
<tr>
<th>Classification</th>
<td>Unclassified
</td>
</tr></table>
<p>
<div>
<pre>We're not matching shuffles that correspond to vperm2*128 instructions with a
zero operand. Note that in some cases, this is already lowered to xor + blend,
and that would be preferred to a vperm2 because xor is free and blends are
always better than or equal to permutes; but if -Oz, then choose vperm2 for the
size savings.
Also, we should be canonicalizing shuffles with one constant vector input to
make life easier for backends to match patterns like this.
Here's the complete list of vperm2 with zero possibilities:
define <4 x double> @vperm2z_0x08(<4 x double> %a) {
%s = shufflevector <4 x double> %a, <4 x double> <double 0.0, double 0.0,
double undef, double undef>, <4 x i32> <i32 4, i32 5, i32 0, i32 1>
ret <4 x double> %s
}
define <4 x double> @vperm2z_0x18(<4 x double> %a) {
%s = shufflevector <4 x double> %a, <4 x double> <double 0.0, double 0.0,
double undef, double undef>, <4 x i32> <i32 4, i32 5, i32 2, i32 3>
ret <4 x double> %s
}
define <4 x double> @vperm2z_0x28(<4 x double> %a) {
%s = shufflevector <4 x double> <double 0.0, double 0.0, double undef, double
undef>, <4 x double> %a, <4 x i32> <i32 0, i32 1, i32 4, i32 5>
ret <4 x double> %s
}
define <4 x double> @vperm2z_0x38(<4 x double> %a) {
%s = shufflevector <4 x double> <double 0.0, double 0.0, double undef, double
undef>, <4 x double> %a, <4 x i32> <i32 0, i32 1, i32 6, i32 7>
ret <4 x double> %s
}
define <4 x double> @vperm2z_0x80(<4 x double> %a) {
%s = shufflevector <4 x double> %a, <4 x double> <double 0.0, double 0.0,
double undef, double undef>, <4 x i32> <i32 0, i32 1, i32 4, i32 5>
ret <4 x double> %s
}
define <4 x double> @vperm2z_0x81(<4 x double> %a) {
%s = shufflevector <4 x double> %a, <4 x double> <double 0.0, double 0.0,
double undef, double undef>, <4 x i32> <i32 2, i32 3, i32 4, i32 5>
ret <4 x double> %s
}
define <4 x double> @vperm2z_0x82(<4 x double> %a) {
%s = shufflevector <4 x double> <double 0.0, double 0.0, double undef, double
undef>, <4 x double> %a, <4 x i32> <i32 4, i32 5, i32 0, i32 1>
ret <4 x double> %s
}
define <4 x double> @vperm2z_0x83(<4 x double> %a) {
%s = shufflevector <4 x double> <double 0.0, double 0.0, double undef, double
undef>, <4 x double> %a, <4 x i32> <i32 6, i32 7, i32 0, i32 1>
ret <4 x double> %s
}
$ llc vpz.ll -mattr=avx -o -
_vperm2z_0x08:
vxorps %ymm1, %ymm1, %ymm1
vinsertf128 $1, %xmm0, %ymm1, %ymm0
retq
_vperm2z_0x18:
vxorpd %ymm1, %ymm1, %ymm1
vblendpd $12, %ymm0, %ymm1, %ymm0 ## ymm0 = ymm1[0,1],ymm0[2,3]
retq
_vperm2z_0x28:
vxorps %ymm1, %ymm1, %ymm1
vinsertf128 $1, %xmm0, %ymm1, %ymm0
retq
_vperm2z_0x38:
vxorpd %ymm1, %ymm1, %ymm1
vblendpd $12, %ymm0, %ymm1, %ymm0 ## ymm0 = ymm1[0,1],ymm0[2,3]
retq
_vperm2z_0x80:
vxorps %ymm1, %ymm1, %ymm1
vinsertf128 $1, %xmm1, %ymm0, %ymm0
retq
_vperm2z_0x81:
vxorps %ymm1, %ymm1, %ymm1
vperm2f128 $33, %ymm1, %ymm0, %ymm0 ## ymm0 = ymm0[2,3],ymm1[0,1]
retq
_vperm2z_0x82:
vxorps %ymm1, %ymm1, %ymm1
vinsertf128 $1, %xmm1, %ymm0, %ymm0
retq
_vperm2z_0x83:
vxorps %ymm1, %ymm1, %ymm1
vperm2f128 $33, %ymm1, %ymm0, %ymm0 ## ymm0 = ymm0[2,3],ymm1[0,1]
retq</pre>
</div>
</p>
<hr>
<span>You are receiving this mail because:</span>
<ul>
<li>You are on the CC list for the bug.</li>
</ul>
</body>
</html>