Optimize loads from variables that might be shadowed by variables...

src/codegen-ia32.h

 // Copyright 2006-2008 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 249 matching lines @@
   // The following are used by class Reference.
   void LoadReference(Reference* ref);
   void UnloadReference(Reference* ref);
 
   Operand ContextOperand(Register context, int index) const {
     return Operand(context, Context::SlotOffset(index));
   }
 
   Operand SlotOperand(Slot* slot, Register tmp);
 
+  Operand ContextSlotOperandCheckExtensions(Slot* slot,
+                                            Register tmp,
+                                            Label* slow);
 
   // Expressions
   Operand GlobalObject() const {
     return ContextOperand(esi, Context::GLOBAL_INDEX);
   }
 
   void LoadCondition(Expression* x,
                      TypeofState typeof_state,
                      Label* true_target,
                      Label* false_target,
                      bool force_cc);
   void Load(Expression* x, TypeofState typeof_state = NOT_INSIDE_TYPEOF);
   void LoadGlobal();
   void LoadGlobalReceiver(Register scratch);
 
   // Read a value from a slot and leave it on top of the expression stack.
   void LoadFromSlot(Slot* slot, TypeofState typeof_state);
+  void LoadFromGlobalSlotCheckExtensions(Slot* slot,
+                                         TypeofState typeof_state,
+                                         Register tmp,
+                                         Label* slow);
 
   // Special code for typeof expressions: Unfortunately, we must
   // be careful when loading the expression in 'typeof'
   // expressions. We are not allowed to throw reference errors for
   // non-existing properties of the global object, so we must make it
   // look like an explicit property access, instead of an access
   // through the context chain.
   void LoadTypeofExpression(Expression* x);
 
   void ToBoolean(Label* true_target, Label* false_target);
@@ skipping 137 matching lines @@
   friend class VirtualFrame;
   friend class Reference;
 
   DISALLOW_COPY_AND_ASSIGN(CodeGenerator);
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_CODEGEN_IA32_H_