Add type propagation phase in optimizing compiler (work in progress).

runtime/vm/flow_graph_optimizer.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_OPTIMIZER_H_
 #define VM_FLOW_GRAPH_OPTIMIZER_H_
 
 #include "vm/intermediate_language.h"
 
 namespace dart {
@@ skipping 50 matching lines @@
 
   bool is_leaf() const { return is_leaf_; }
 
  private:
   const GrowableArray<BlockEntryInstr*>& blocks_;
   bool is_leaf_;
 
   DISALLOW_COPY_AND_ASSIGN(FlowGraphAnalyzer);
 };
 
+
+class ParsedFunction;
+
+
+class FlowGraphTypePropagator : public FlowGraphVisitor {
+ public:
+  FlowGraphTypePropagator(const ParsedFunction& parsed_function,
+                          const GrowableArray<BlockEntryInstr*>& blocks)
+      : FlowGraphVisitor(blocks),
+        parsed_function_(parsed_function) { }
+  virtual ~FlowGraphTypePropagator() {}
+
+  const ParsedFunction& parsed_function() const { return parsed_function_; }
+
+  void PropagateTypes();
+
+  virtual void VisitAssertAssignable(AssertAssignableComp* comp,
+                                     BindInstr* instr);
+
+  virtual void VisitBind(BindInstr* instr);
+
+ private:
+  const ParsedFunction& parsed_function_;
+  DISALLOW_COPY_AND_ASSIGN(FlowGraphTypePropagator);
+};
+
 }  // namespace dart
 
 #endif  // VM_FLOW_GRAPH_OPTIMIZER_H_