[turbofan] Use appropriate type for NodeId.

src/compiler/graph.h

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_COMPILER_GRAPH_H_
 #define V8_COMPILER_GRAPH_H_
 
 #include "src/zone.h"
 #include "src/zone-containers.h"
 
 namespace v8 {
 namespace internal {
 namespace compiler {
 
 // Forward declarations.
 class GraphDecorator;
 class Node;
 class Operator;
 
 
 // Marks are used during traversal of the graph to distinguish states of nodes.
 // Each node has a mark which is a monotonically increasing integer, and a
 // {NodeMarker} has a range of values that indicate states of a node.
 typedef uint32_t Mark;
 
 
 // NodeIds are identifying numbers for nodes that can be used to index auxiliary
 // out-of-line data associated with each node.
-typedef int32_t NodeId;
+typedef uint32_t NodeId;
 
 
 class Graph : public ZoneObject {
  public:
   explicit Graph(Zone* zone);
 
   // Base implementation used by all factory methods.
   Node* NewNode(const Operator* op, int input_count, Node** inputs,
                 bool incomplete = false);
 
@@ skipping 43 matching lines @@
   template <class Visitor>
   inline void VisitNodeInputsFromEnd(Visitor* visitor);
 
   Zone* zone() const { return zone_; }
   Node* start() const { return start_; }
   Node* end() const { return end_; }
 
   void SetStart(Node* start) { start_ = start; }
   void SetEnd(Node* end) { end_ = end; }
 
-  int NodeCount() const { return next_node_id_; }
+  size_t NodeCount() const { return next_node_id_; }
 
   void Decorate(Node* node, bool incomplete);
   void AddDecorator(GraphDecorator* decorator);
   void RemoveDecorator(GraphDecorator* decorator);
 
  private:
   friend class NodeMarkerBase;
 
   inline NodeId NextNodeId();
 
@@ skipping 14 matching lines @@
  public:
   virtual ~GraphDecorator() {}
   virtual void Decorate(Node* node, bool incomplete) = 0;
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_GRAPH_H_