From beb66de0f926dba66a4d0a248a975df427e841f2 Mon Sep 17 00:00:00 2001
From: Elena Demikhovsky <elena.demikhovsky@intel.com>
Date: Thu, 12 Jan 2012 20:33:10 +0000
Subject: [PATCH] Fixed a bug in LowerVECTOR_SHUFFLE caused assertion failure 
 lc: X86ISelLowering.cpp:6480: llvm::SDValue
 llvm::X86TargetLowering::LowerVECTOR_SHUFFLE(llvm::SDValue,
 llvm::SelectionDAG&) const: Assertion `V1.getOpcode() != ISD::UNDEF&&  "Op 1
 of shuffle should not be undef"' failed. Added a test.

llvm-svn: 148044
---
 lib/Target/X86/X86ISelLowering.cpp |  6 +++++-
 test/CodeGen/X86/avx-shuffle.ll    | 10 +++++++++-
 2 files changed, 14 insertions(+), 2 deletions(-)

diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index c643cefb6c0..6a5e6f5f240 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -6464,6 +6464,7 @@ X86TargetLowering::LowerVECTOR_SHUFFLE(SDValue Op, SelectionDAG &DAG) const {
   EVT VT = Op.getValueType();
   DebugLoc dl = Op.getDebugLoc();
   unsigned NumElems = VT.getVectorNumElements();
+  bool V1IsUndef = V1.getOpcode() == ISD::UNDEF;
   bool V2IsUndef = V2.getOpcode() == ISD::UNDEF;
   bool V1IsSplat = false;
   bool V2IsSplat = false;
@@ -6475,7 +6476,10 @@ X86TargetLowering::LowerVECTOR_SHUFFLE(SDValue Op, SelectionDAG &DAG) const {
 
   assert(VT.getSizeInBits() != 64 && "Can't lower MMX shuffles");
 
-  assert(V1.getOpcode() != ISD::UNDEF && "Op 1 of shuffle should not be undef");
+  if (V1IsUndef && V2IsUndef)
+    return DAG.getUNDEF(VT);
+
+  assert(!V1IsUndef && "Op 1 of shuffle should not be undef");
 
   // Vector shuffle lowering takes 3 steps:
   //
diff --git a/test/CodeGen/X86/avx-shuffle.ll b/test/CodeGen/X86/avx-shuffle.ll
index ad611fc1b53..bb55ab6acdb 100644
--- a/test/CodeGen/X86/avx-shuffle.ll
+++ b/test/CodeGen/X86/avx-shuffle.ll
@@ -54,4 +54,12 @@ entry:
 ; CHECK-NOT: vinsertf128
   %shuffle.i = shufflevector <2 x double> %1, <2 x double> <double 0.000000e+00, double undef>, <4 x i32> <i32 0, i32 1, i32 2, i32 2>
   ret <4 x double> %shuffle.i
-}
\ No newline at end of file
+}
+
+define <16 x i16> @test7(<4 x i16> %a) nounwind {
+; CHECK: test7
+
+  %b = shufflevector <4 x i16> %a, <4 x i16> undef, <16 x i32> <i32 1, i32 1, i32 undef, i32 undef, i32 undef, i32 undef, i32 undef, i32 undef, i32 undef, i32 undef, i32 undef, i32 undef, i32 undef, i32 undef, i32 undef, i32 undef>
+  ret <16 x i16> %b
+}
+