+static
+SDValue combineSelectAndUse(SDNode *N, SDValue Slct, SDValue OtherOp,
+ TargetLowering::DAGCombinerInfo &DCI) {
+
+ SelectionDAG &DAG = DCI.DAG;
+ const TargetLowering &TLI = DAG.getTargetLoweringInfo();
+ MVT VT = N->getValueType(0);
+ unsigned Opc = N->getOpcode();
+ bool isSlctCC = Slct.getOpcode() == ISD::SELECT_CC;
+ SDValue LHS = isSlctCC ? Slct.getOperand(2) : Slct.getOperand(1);
+ SDValue RHS = isSlctCC ? Slct.getOperand(3) : Slct.getOperand(2);
+ ISD::CondCode CC = ISD::SETCC_INVALID;
+
+ if (isSlctCC) {
+ CC = cast<CondCodeSDNode>(Slct.getOperand(4))->get();
+ } else {
+ SDValue CCOp = Slct.getOperand(0);
+ if (CCOp.getOpcode() == ISD::SETCC)
+ CC = cast<CondCodeSDNode>(CCOp.getOperand(2))->get();
+ }
+
+ bool DoXform = false;
+ bool InvCC = false;
+ assert ((Opc == ISD::ADD || (Opc == ISD::SUB && Slct == N->getOperand(1))) &&
+ "Bad input!");
+
+ if (LHS.getOpcode() == ISD::Constant &&
+ cast<ConstantSDNode>(LHS)->isNullValue()) {
+ DoXform = true;
+ } else if (CC != ISD::SETCC_INVALID &&
+ RHS.getOpcode() == ISD::Constant &&
+ cast<ConstantSDNode>(RHS)->isNullValue()) {
+ std::swap(LHS, RHS);
+ SDValue Op0 = Slct.getOperand(0);
+ MVT OpVT = isSlctCC ? Op0.getValueType() :
+ Op0.getOperand(0).getValueType();
+ bool isInt = OpVT.isInteger();
+ CC = ISD::getSetCCInverse(CC, isInt);
+
+ if (!TLI.isCondCodeLegal(CC, OpVT))
+ return SDValue(); // Inverse operator isn't legal.
+
+ DoXform = true;
+ InvCC = true;
+ }
+
+ if (DoXform) {
+ SDValue Result = DAG.getNode(Opc, RHS.getDebugLoc(), VT, OtherOp, RHS);
+ if (isSlctCC)
+ return DAG.getSelectCC(N->getDebugLoc(), OtherOp, Result,
+ Slct.getOperand(0), Slct.getOperand(1), CC);
+ SDValue CCOp = Slct.getOperand(0);
+ if (InvCC)
+ CCOp = DAG.getSetCC(Slct.getDebugLoc(), CCOp.getValueType(),
+ CCOp.getOperand(0), CCOp.getOperand(1), CC);
+ return DAG.getNode(ISD::SELECT, N->getDebugLoc(), VT,
+ CCOp, OtherOp, Result);
+ }
+ return SDValue();
+}
+
+/// PerformADDCombine - Target-specific dag combine xforms for ISD::ADD.
+static SDValue PerformADDCombine(SDNode *N,
+ TargetLowering::DAGCombinerInfo &DCI) {
+ // added by evan in r37685 with no testcase.
+ SDValue N0 = N->getOperand(0), N1 = N->getOperand(1);
+
+ // fold (add (select cc, 0, c), x) -> (select cc, x, (add, x, c))
+ if (N0.getOpcode() == ISD::SELECT && N0.getNode()->hasOneUse()) {
+ SDValue Result = combineSelectAndUse(N, N0, N1, DCI);
+ if (Result.getNode()) return Result;
+ }
+ if (N1.getOpcode() == ISD::SELECT && N1.getNode()->hasOneUse()) {
+ SDValue Result = combineSelectAndUse(N, N1, N0, DCI);
+ if (Result.getNode()) return Result;
+ }
+
+ return SDValue();
+}
+
+/// PerformSUBCombine - Target-specific dag combine xforms for ISD::SUB.
+static SDValue PerformSUBCombine(SDNode *N,
+ TargetLowering::DAGCombinerInfo &DCI) {
+ // added by evan in r37685 with no testcase.
+ SDValue N0 = N->getOperand(0), N1 = N->getOperand(1);
+
+ // fold (sub x, (select cc, 0, c)) -> (select cc, x, (sub, x, c))
+ if (N1.getOpcode() == ISD::SELECT && N1.getNode()->hasOneUse()) {
+ SDValue Result = combineSelectAndUse(N, N1, N0, DCI);
+ if (Result.getNode()) return Result;
+ }
+
+ return SDValue();
+}
+
+