[VP][DAGCombiner] Remove unused-private-field VPMatchContext.Root

[DamonFool]

Summary

LLVM fails to build after D141891 due to -Wunused-private-field of VPMatchContext.Root
llvm-project/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp:870:11: error: private field 'Root' is not used [-Werror,-Wunused-private-field]

SDNode *Root;
        ^

1 error generated.

[fakepaper56]

LGTM. Thank you.

[DamonFool]

Thanks @fakepaper56 for your review.
It had been fixed by @MaskRay .
So just close it.

llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp

public:
   // Same as SelectionDAG::getNode().
   template <typename... ArgT> SDValue getNode(ArgT &&...Args) {
     return DAG.getNode(std::forward<ArgT>(Args)...);
   }
 };
 
 class VPMatchContext {
   SelectionDAG &DAG;
-  SDNode *Root;
   SDValue RootMaskOp;
   SDValue RootVectorLenOp;
 
 public:
   VPMatchContext(SelectionDAG &DAG, SDNode *Root)
-      : DAG(DAG), Root(Root), RootMaskOp(), RootVectorLenOp() {
+      : DAG(DAG), RootMaskOp(), RootVectorLenOp() {
     assert(Root->isVPOpcode());
     if (auto RootMaskPos = ISD::getVPMaskIdx(Root->getOpcode()))
       RootMaskOp = Root->getOperand(*RootMaskPos);
 
     if (auto RootVLenPos =
             ISD::getVPExplicitVectorLengthIdx(Root->getOpcode()))
       RootVectorLenOp = Root->getOperand(*RootVLenPos);
   }