[turbofan] Smartify the GraphReducer.

src/compiler/graph-reducer.h

Index: src/compiler/graph-reducer.h
diff --git a/src/compiler/graph-reducer.h b/src/compiler/graph-reducer.h
index e0e4f7a3d30b14b53f246efe8b3f5d221be17052..fe156b3a1590ccd1678a01284307570c567fadbc 100644
--- a/src/compiler/graph-reducer.h
+++ b/src/compiler/graph-reducer.h
@@ -56,19 +56,39 @@ class Reducer {
 class GraphReducer FINAL {
  public:
   explicit GraphReducer(Graph* graph);
+  GraphReducer(Graph* graph, Zone* zone);
 
   Graph* graph() const { return graph_; }
 
-  void AddReducer(Reducer* reducer) { reducers_.push_back(reducer); }
+  void AddReducer(Reducer* reducer);
 
   // Reduce a single node.
-  void ReduceNode(Node* node);
+  void ReduceNode(Node* const);
   // Reduce the whole graph.
   void ReduceGraph();
 
  private:
+  enum class State : uint8_t;
+
+  // Reduce a single node.
+  Reduction Reduce(Node* const);
+  // Reduce the node on top of the stack.
+  void ReduceTop();
+
+  // Node stack operations.
+  void Pop();
+  void Push(Node* const);
+  Node* Top() const;
+
+  // Revisit queue operations.
+  bool Recurse(Node* const);
+  void Revisit(Node* const);
+
   Graph* graph_;
   ZoneVector<Reducer*> reducers_;
+  ZoneStack<Node*> revisit_;
+  ZoneStack<Node*> stack_;
+  ZoneDeque<State> state_;
 
   DISALLOW_COPY_AND_ASSIGN(GraphReducer);
 };