From 2091df3d09bba0705fc62d020e5177a246d67978 Mon Sep 17 00:00:00 2001
From: Craig Topper <craig.topper@gmail.com>
Date: Tue, 17 Apr 2012 05:54:54 +0000
Subject: [PATCH] Don't decode vperm2i128 or vperm2f128 into a shuffle if bit 3
 or 7 of the immediate is set.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@154907 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Target/X86/Utils/X86ShuffleDecode.cpp | 3 +++
 lib/Target/X86/X86ISelLowering.cpp        | 1 +
 2 files changed, 4 insertions(+)

diff --git a/lib/Target/X86/Utils/X86ShuffleDecode.cpp b/lib/Target/X86/Utils/X86ShuffleDecode.cpp
index 32c722acc43..a802333002d 100644
--- a/lib/Target/X86/Utils/X86ShuffleDecode.cpp
+++ b/lib/Target/X86/Utils/X86ShuffleDecode.cpp
@@ -169,6 +169,9 @@ void DecodeUNPCKLMask(EVT VT, SmallVectorImpl<int> &ShuffleMask) {
 
 void DecodeVPERM2X128Mask(EVT VT, unsigned Imm,
                           SmallVectorImpl<int> &ShuffleMask) {
+  if (Imm & 0x88)
+    return; // Not a shuffle
+
   unsigned HalfSize = VT.getVectorNumElements()/2;
   unsigned FstHalfBegin = (Imm & 0x3) * HalfSize;
   unsigned SndHalfBegin = ((Imm >> 4) & 0x3) * HalfSize;
diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 8418bb12b99..1ff60dc4368 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -4430,6 +4430,7 @@ static bool getTargetShuffleMask(SDNode *N, EVT VT,
   case X86ISD::VPERM2X128:
     ImmN = N->getOperand(N->getNumOperands()-1);
     DecodeVPERM2X128Mask(VT, cast<ConstantSDNode>(ImmN)->getZExtValue(), Mask);
+    if (Mask.empty()) return false;
     break;
   case X86ISD::MOVDDUP:
   case X86ISD::MOVLHPD: