Optimizes 'as' operation in similar way as 'instanceof': collect type feedback in unoptimized mode…

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 300 matching lines @@
 
   Value* BuildNullValue();
 
  private:
   // Specify a definition of the final result.  Adds the definition to
   // the graph, but normally overridden in subclasses.
   virtual void ReturnDefinition(Definition* definition) {
     Do(definition);
   }
 
+ protected:
   // Returns true if the run-time type check can be eliminated.
   bool CanSkipTypeCheck(intptr_t token_pos,
                         Value* value,
                         const AbstractType& dst_type,
                         const String& dst_name);
 
+ private:
   // Shared global state.
   FlowGraphBuilder* owner_;
 
   // Input parameters.
   intptr_t temp_index_;
 
   // Output parameters.
   Instruction* entry_;
   Instruction* exit_;
 };
@@ skipping 108 matching lines @@
   // Output parameters.
   GrowableArray<TargetEntryInstr**> true_successor_addresses_;
   GrowableArray<TargetEntryInstr**> false_successor_addresses_;
 
   intptr_t condition_token_pos_;
 };
 
 }  // namespace dart
 
 #endif  // VM_FLOW_GRAPH_BUILDER_H_