<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">No, but we don’t seem to have a hard rule that VECTOR_SHUFFLE can only use (-1) to define undefined mask elements - AFAICT it can be any negative value. This is preventing us from sharing a number of chunks of x86 shuffle matching code that current use Mask[i] < 0 to match all undefineds. <div class=""><br class=""><div class="">Simon.<div class=""><br class=""><div><blockquote type="cite" class=""><div class="">On 7 Aug 2016, at 16:56, Craig Topper <<a href="mailto:craig.topper@gmail.com" class="">craig.topper@gmail.com</a>> wrote:</div><br class="Apple-interchange-newline"><div class="">I don't quite understand this. Does combining come through lowerVectorShuffle? Or when would a VECTOR_SHUFFLE come through where this wasn't true?<span class=""></span><br class=""><br class="">On Sunday, August 7, 2016, Simon Pilgrim via llvm-commits <<a href="mailto:llvm-commits@lists.llvm.org" class="">llvm-commits@lists.llvm.org</a>> wrote:<br class=""><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">Author: rksimon<br class="">
Date: Sun Aug 7 10:29:12 2016<br class="">
New Revision: 277959<br class="">
<br class="">
URL: <a href="http://llvm.org/viewvc/llvm-project?rev=277959&view=rev" target="_blank" class="">http://llvm.org/viewvc/llvm-<wbr class="">project?rev=277959&view=rev</a><br class="">
Log:<br class="">
[X86] lowerVectorShuffle - ensure that undefined mask elements only use SM_SentinelUndef<br class="">
<br class="">
Help lowering and combining (which can specify SM_SentinelZero mask elements) share more shuffle matching code.<br class="">
<br class="">
Modified:<br class="">
llvm/trunk/lib/Target/X86/<wbr class="">X86ISelLowering.cpp<br class="">
<br class="">
Modified: llvm/trunk/lib/Target/X86/<wbr class="">X86ISelLowering.cpp<br class="">
URL: <a href="http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86ISelLowering.cpp?rev=277959&r1=277958&r2=277959&view=diff" target="_blank" class="">http://llvm.org/viewvc/llvm-<wbr class="">project/llvm/trunk/lib/Target/<wbr class="">X86/X86ISelLowering.cpp?rev=<wbr class="">277959&r1=277958&r2=277959&<wbr class="">view=diff</a><br class="">
==============================<wbr class="">==============================<wbr class="">==================<br class="">
--- llvm/trunk/lib/Target/X86/<wbr class="">X86ISelLowering.cpp (original)<br class="">
+++ llvm/trunk/lib/Target/X86/<wbr class="">X86ISelLowering.cpp Sun Aug 7 10:29:12 2016<br class="">
@@ -12281,6 +12281,15 @@ static SDValue lowerVectorShuffle(SDValu<br class="">
return DAG.getVectorShuffle(VT, DL, V1, V2, NewMask);<br class="">
}<br class="">
<br class="">
+ // Ensure that undefined mask elements only use SM_SentinelUndef.<br class="">
+ if (llvm::any_of(Mask, [](int M) { return M < SM_SentinelUndef; })) {<br class="">
+ SmallVector<int, 8> NewMask(Mask.begin(), Mask.end());<br class="">
+ for (int &M : NewMask)<br class="">
+ if (M < SM_SentinelUndef)<br class="">
+ M = SM_SentinelUndef;<br class="">
+ return DAG.getVectorShuffle(VT, DL, V1, V2, NewMask);<br class="">
+ }<br class="">
+<br class="">
// We actually see shuffles that are entirely re-arrangements of a set of<br class="">
// zero inputs. This mostly happens while decomposing complex shuffles into<br class="">
// simple ones. Directly lower these as a buildvector of zeros.<br class="">
<br class="">
<br class="">
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</blockquote><br class=""><br class="">-- <br class="">~Craig<br class="">
</div></blockquote></div><br class=""></div></div></div></body></html>