fix a case where all operands of BUILD_VECTOR are undefined



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@162214 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index e4af736..1bbd4a7 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -5180,6 +5180,10 @@
     Mask.push_back(cast<ConstantSDNode>(L2In.getOperand(1))->getZExtValue());
   }
 
+  // Quit if all operands of BUILD_VECTOR are undefined.
+  if (!VecIn.getNode())
+    return SDValue();
+
   // Fill the remaining mask as undef.
   for (unsigned i = NumElts; i < VecInVT.getVectorNumElements(); ++i)
     Mask.push_back(-1);