Fix several places to handle vector operands properly.
Based on a patch by Micah Villmow for PR6438.

llvm-svn: 97538
diff --git a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
index eca9f3f..0e54ca4 100644
--- a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -1608,7 +1608,7 @@
 
   // Fall back to ComputeMaskedBits to catch other known cases.
   EVT OpVT = Val.getValueType();
-  unsigned BitWidth = OpVT.getSizeInBits();
+  unsigned BitWidth = OpVT.getScalarType().getSizeInBits();
   APInt Mask = APInt::getAllOnesValue(BitWidth);
   APInt KnownZero, KnownOne;
   DAG.ComputeMaskedBits(Val, Mask, KnownZero, KnownOne);