Implement a simple InstructionVisitor class.

runtime/vm/flow_graph_builder.h

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #ifndef VM_FLOW_GRAPH_BUILDER_H_
 #define VM_FLOW_GRAPH_BUILDER_H_
 
 #include "vm/allocation.h"
 #include "vm/ast.h"
 #include "vm/growable_array.h"
@@ skipping 16 matching lines @@
 
   const ParsedFunction& parsed_function() const { return parsed_function_; }
 
   bool HasBailedOut() const { return bailout_reason_ != NULL; }
   void Bailout(const char* reason) {
     // Cannot give a NULL reason because we use it to detect bailout.
     ASSERT(!HasBailedOut() && (reason != NULL));
     bailout_reason_ = reason;
   }
   void TraceBailout() const;
-  void PrintGraph() const;
 
  private:
   const ParsedFunction& parsed_function_;
   const char* bailout_reason_;
-  GrowableArray<Instruction*> postorder_block_entries_;
+  GrowableArray<BlockEntryInstr*> postorder_block_entries_;
 };
 
 
 #define DEFINE_VISIT(type, name) virtual void Visit##type(type* node);
 
 class TestGraphVisitor;
 
 // Translate an AstNode to a control-flow graph fragment for its effects
 // (e.g., a statement or an expression in an effect context).  Implements a
 // function from an AstNode and next temporary index to a graph fragment
@@ skipping 160 matching lines @@
   TargetEntryInstr** true_successor_address_;
   TargetEntryInstr** false_successor_address_;
 };
 
 #undef DEFINE_VISIT
 
 
 }  // namespace dart
 
 #endif  // VM_FLOW_GRAPH_BUILDER_H_