[turbofan] Make sure Operator is really immutable.

src/compiler/node.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_NODE_H_
 #define V8_COMPILER_NODE_H_
 
 #include <deque>
 #include <set>
 #include <vector>
 
 #include "src/compiler/generic-algorithm.h"
 #include "src/compiler/generic-node.h"
 #include "src/compiler/opcodes.h"
 #include "src/compiler/operator.h"
 #include "src/types.h"
 #include "src/zone.h"
 #include "src/zone-allocator.h"
 
 namespace v8 {
 namespace internal {
 namespace compiler {
 
 class NodeData {
  public:
-  Operator* op() const { return op_; }
-  void set_op(Operator* op) { op_ = op; }
+  const Operator* op() const { return op_; }
+  void set_op(const Operator* op) { op_ = op; }
 
   IrOpcode::Value opcode() const {
     DCHECK(op_->opcode() <= IrOpcode::kLast);
     return static_cast<IrOpcode::Value>(op_->opcode());
   }
 
   Bounds bounds() { return bounds_; }
 
  protected:
-  Operator* op_;
+  const Operator* op_;
   Bounds bounds_;
   explicit NodeData(Zone* zone) : bounds_(Bounds(Type::None(zone))) {}
 
   friend class NodeProperties;
   void set_bounds(Bounds b) { bounds_ = b; }
 };
 
 // A Node is the basic primitive of an IR graph. In addition to the members
 // inherited from Vector, Nodes only contain a mutable Operator that may change
 // during compilation, e.g. during lowering passes.  Other information that
 // needs to be associated with Nodes during compilation must be stored
 // out-of-line indexed by the Node's id.
-class Node : public GenericNode<NodeData, Node> {
+class Node FINAL : public GenericNode<NodeData, Node> {
  public:
   Node(GenericGraphBase* graph, int input_count)
       : GenericNode<NodeData, Node>(graph, input_count) {}
 
-  void Initialize(Operator* op) { set_op(op); }
+  void Initialize(const Operator* op) { set_op(op); }
   void Kill();
 
   void CollectProjections(ZoneVector<Node*>* projections);
   Node* FindProjection(int32_t projection_index);
 };
 
 OStream& operator<<(OStream& os, const Node& n);
 
 typedef GenericGraphVisit::NullNodeVisitor<NodeData, Node> NullNodeVisitor;
 
 typedef std::set<Node*, std::less<Node*>, zone_allocator<Node*> > NodeSet;
 typedef NodeSet::iterator NodeSetIter;
 typedef NodeSet::reverse_iterator NodeSetRIter;
 
 typedef ZoneVector<Node*> NodeVector;
 typedef NodeVector::iterator NodeVectorIter;
 typedef NodeVector::reverse_iterator NodeVectorRIter;
 
 typedef ZoneVector<NodeVector> NodeVectorVector;
 typedef NodeVectorVector::iterator NodeVectorVectorIter;
 typedef NodeVectorVector::reverse_iterator NodeVectorVectorRIter;
 
 typedef Node::Uses::iterator UseIter;
 typedef Node::Inputs::iterator InputIter;
 
-// Helper to extract parameters from Operator1<*> operator.
+// Helper to extract parameters from Operator1<*> nodes.
 template <typename T>
-static inline T OpParameter(Operator* op) {
-  return reinterpret_cast<Operator1<T>*>(op)->parameter();
+static inline T OpParameter(const Node* node) {
+  return OpParameter<T>(node->op());
 }
 
-
-// Helper to extract parameters from Operator1<*> nodes.
-template <typename T>
-static inline T OpParameter(Node* node) {
-  return OpParameter<T>(node->op());
-}
-}
-}
-}  // namespace v8::internal::compiler
+}  // namespace compiler
+}  // namespace internal
+}  // namespace v8
 
 #endif  // V8_COMPILER_NODE_H_