+ // If we found that truncation is beneficial, perform the truncation and
+ // update 'Op'.
+ if (NeedTruncation) {
+ EVT VT = Op.getValueType();
+ SDValue WideVal = Op->getOperand(0);
+ EVT WideVT = WideVal.getValueType();
+ unsigned ConvertedOp = 0;
+ // Use a target machine opcode to prevent further DAGCombine
+ // optimizations that may separate the arithmetic operations
+ // from the setcc node.
+ switch (WideVal.getOpcode()) {
+ default: break;
+ case ISD::ADD: ConvertedOp = X86ISD::ADD; break;
+ case ISD::SUB: ConvertedOp = X86ISD::SUB; break;
+ case ISD::AND: ConvertedOp = X86ISD::AND; break;
+ case ISD::OR: ConvertedOp = X86ISD::OR; break;
+ case ISD::XOR: ConvertedOp = X86ISD::XOR; break;
+ }
+
+ if (ConvertedOp) {
+ const TargetLowering &TLI = DAG.getTargetLoweringInfo();
+ if (TLI.isOperationLegal(WideVal.getOpcode(), WideVT)) {
+ SDValue V0 = DAG.getNode(ISD::TRUNCATE, dl, VT, WideVal.getOperand(0));
+ SDValue V1 = DAG.getNode(ISD::TRUNCATE, dl, VT, WideVal.getOperand(1));
+ Op = DAG.getNode(ConvertedOp, dl, VT, V0, V1);
+ }
+ }
+ }
+