[SelectionDAG] Propogate Disjoint flag.

Author: fengfeng09

llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp

@@ -9530,6 +9530,8 @@ static SDValue combineShiftOfShiftedLogic(SDNode *Shift, SelectionDAG &DAG) {
   SDValue ShiftSumC = DAG.getConstant(*C0Val + C1Val, DL, ShiftAmtVT);
   SDValue NewShift1 = DAG.getNode(ShiftOpcode, DL, VT, X, ShiftSumC);
   SDValue NewShift2 = DAG.getNode(ShiftOpcode, DL, VT, Y, C1);
+  // Propogate flags.
+  SelectionDAG::FlagInserter FlagsInserter(DAG, LogicOp->getFlags());
   return DAG.getNode(LogicOpcode, DL, VT, NewShift1, NewShift2);
 }
 

llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp

@@ -544,6 +544,8 @@ bool TargetLowering::ShrinkDemandedConstant(SDValue Op,
     if (!C.isSubsetOf(DemandedBits)) {
       EVT VT = Op.getValueType();
       SDValue NewC = TLO.DAG.getConstant(DemandedBits & C, DL, VT);
+      // Propogate flags.
+      SelectionDAG::FlagInserter FlagsInserter(TLO.DAG, Op->getFlags());
       SDValue NewOp = TLO.DAG.getNode(Opcode, DL, VT, Op.getOperand(0), NewC);
       return TLO.CombineTo(Op, NewOp);
     }