<div dir="ltr"><br><div class="gmail_extra"><br><div class="gmail_quote">On Sun, Aug 13, 2017 at 10:40 AM, Craig Topper via llvm-commits <span dir="ltr"><<a href="mailto:llvm-commits@lists.llvm.org" target="_blank">llvm-commits@lists.llvm.org</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">Author: ctopper<br>
Date: Sun Aug 13 10:40:02 2017<br>
New Revision: 310794<br>
<br>
URL: <a href="http://llvm.org/viewvc/llvm-project?rev=310794&view=rev" rel="noreferrer" target="_blank">http://llvm.org/viewvc/llvm-<wbr>project?rev=310794&view=rev</a><br>
Log:<br>
[AVX512] Correct isExtractSubvectorCheap so that it will return the correct answers for extracting 128-bits from a 512-bit vector and for mask registers.<br>
<br>
Previously it would not return true for extracting either of the upper quarters of a 512-bit registers.<br>
<br>
For mask registers we support extracting anything from index 0. And otherwise we only support extracting the upper half of a register.<br>
<br>
Differential Revision: <a href="https://reviews.llvm.org/D36638" rel="noreferrer" target="_blank">https://reviews.llvm.org/<wbr>D36638</a><br>
<br>
Modified:<br>
    llvm/trunk/lib/Target/X86/<wbr>X86ISelLowering.cpp<br>
<br>
Modified: llvm/trunk/lib/Target/X86/<wbr>X86ISelLowering.cpp<br>
URL: <a href="http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86ISelLowering.cpp?rev=310794&r1=310793&r2=310794&view=diff" rel="noreferrer" target="_blank">http://llvm.org/viewvc/llvm-<wbr>project/llvm/trunk/lib/Target/<wbr>X86/X86ISelLowering.cpp?rev=<wbr>310794&r1=310793&r2=310794&<wbr>view=diff</a><br>
==============================<wbr>==============================<wbr>==================<br>
--- llvm/trunk/lib/Target/X86/<wbr>X86ISelLowering.cpp (original)<br>
+++ llvm/trunk/lib/Target/X86/<wbr>X86ISelLowering.cpp Sun Aug 13 10:40:02 2017<br>
@@ -4579,7 +4579,13 @@ bool X86TargetLowering::<wbr>isExtractSubvect<br>
   if (!isOperationLegalOrCustom(<wbr>ISD::EXTRACT_SUBVECTOR, ResVT))<br>
     return false;<br>
<br>
-  return (Index == 0 || Index == ResVT.getVectorNumElements());<br>
+  // Mask vectors support all subregister combinations and operations that<br>
+  // extract half of vector.<br>
+  if (ResVT.getVectorElementType() == MVT::i1)<br>
+    return Index = 0 || ((ResVT.getSizeInBits() == SrcVT.getSizeInBits() * 2) &&<br>
+                         (Index == ResVT.getVectorNumElements()))<wbr>;<br></blockquote><div><br></div><div><br></div><div>Is this supposed to be `Index == 0`?</div><div><br></div><div>I'm getting this warning (`gcc version 5.4.0 20160609 (Ubuntu 5.4.0-6ubuntu1~16.04.4) `):</div><div><br></div><div><div>/home/sean/pg/llvm/llvm/lib/Target/X86/X86ISelLowering.cpp: In member function ‘virtual bool llvm::X86TargetLowering::isExtractSubvectorCheap(llvm::EVT, llvm::EVT, unsigned int) const’:</div><div>/home/sean/pg/llvm/llvm/lib/Target/X86/X86ISelLowering.cpp:4586:65: warning: suggest parentheses around assignment used as truth value [-Wparentheses]</div><div>                          (Index == ResVT.getVectorNumElements()));</div><div>                                                                 ^</div></div><div><br></div><div><br></div><div>-- Sean Silva</div><div> </div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
+<br>
+  return (Index % ResVT.getVectorNumElements()) == 0;<br>
 }<br>
<br>
 bool X86TargetLowering::<wbr>isCheapToSpeculateCttz() const {<br>
<br>
<br>
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</blockquote></div><br></div></div>