address comment

Author: RolandF77

llvm/lib/Target/PowerPC/PPCISelLowering.cpp

@@ -9802,6 +9802,7 @@ SDValue PPCTargetLowering::LowerBUILD_VECTOR(SDValue Op,
                                   dl);
 
   // If the sign extended value is in the range [-16,15], use VSPLTI[bhw].
+  // Use VSPLTIW/VUPKLSW for v2i64 in range [-16,15].
   if (SextVal >= -16 && SextVal <= 15) {
     unsigned UseSize = SplatSize == 8 ? 4 : SplatSize;
     SDValue Res =