Implement loop variable assignment analysis.

src/compiler/control-builders.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_CONTROL_BUILDERS_H_
 #define V8_COMPILER_CONTROL_BUILDERS_H_
 
 #include "src/v8.h"
 
 #include "src/compiler/graph-builder.h"
@@ skipping 52 matching lines @@
 // Tracks control flow for an iteration statement.
 class LoopBuilder : public ControlBuilder {
  public:
   explicit LoopBuilder(StructuredGraphBuilder* builder)
       : ControlBuilder(builder),
         loop_environment_(NULL),
         continue_environment_(NULL),
         break_environment_(NULL) {}
 
   // Primitive control commands.
-  void BeginLoop();
+  void BeginLoop(BitVector* assigned);
   void EndBody();
   void EndLoop();
 
   // Primitive support for break and continue.
   virtual void Continue();
   virtual void Break();
 
   // Compound control command for conditional break.
   void BreakUnless(Node* condition);
 
@@ skipping 51 matching lines @@
   virtual void Break();
 
  private:
   Environment* break_environment_;  // Environment after the block exits.
 };
 }
 }
 }  // namespace v8::internal::compiler
 
 #endif  // V8_COMPILER_CONTROL_BUILDERS_H_