First step in letting Crankshaft inline functions with a different context.

src/hydrogen.h

 // Copyright 2011 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 304 matching lines @@
                Scope* scope,
                Handle<JSFunction> closure);
 
   // Simple accessors.
   Handle<JSFunction> closure() const { return closure_; }
   const ZoneList<HValue*>* values() const { return &values_; }
   const ZoneList<int>* assigned_variables() const {
     return &assigned_variables_;
   }
   int parameter_count() const { return parameter_count_; }
+  int specials_count() const { return specials_count_; }
   int local_count() const { return local_count_; }
   HEnvironment* outer() const { return outer_; }
   int pop_count() const { return pop_count_; }
   int push_count() const { return push_count_; }
 
   int ast_id() const { return ast_id_; }
   void set_ast_id(int id) { ast_id_ = id; }
 
   int length() const { return values_.length(); }
+  bool is_special_index(int i) const {
+    return i >= parameter_count() && i < parameter_count() + specials_count();
+  }
 
   void Bind(Variable* variable, HValue* value) {
     Bind(IndexFor(variable), value);
   }
 
   void Bind(int index, HValue* value);
 
+  void BindContext(HValue* value) {
+    Bind(parameter_count(), value);
+  }
+
   HValue* Lookup(Variable* variable) const {
     return Lookup(IndexFor(variable));
   }
 
   HValue* Lookup(int index) const {
     HValue* result = values_[index];
     ASSERT(result != NULL);
     return result;
   }
 
+  HValue* LookupContext() const {
+    // Return first special.
+    return Lookup(parameter_count());
+  }
+
   void Push(HValue* value) {
     ASSERT(value != NULL);
     ++push_count_;
     values_.Add(value);
   }
 
   HValue* Pop() {
     ASSERT(!ExpressionStackIsEmpty());
     if (push_count_ > 0) {
       --push_count_;
     } else {
       ++pop_count_;
     }
     return values_.RemoveLast();
   }
 
   void Drop(int count);
 
   HValue* Top() const { return ExpressionStackAt(0); }
 
+  bool ExpressionStackIsEmpty() const;
+
   HValue* ExpressionStackAt(int index_from_top) const {
     int index = length() - index_from_top - 1;
     ASSERT(HasExpressionAt(index));
     return values_[index];
   }
 
   void SetExpressionStackAt(int index_from_top, HValue* value);
 
   HEnvironment* Copy() const;
   HEnvironment* CopyWithoutHistory() const;
@@ skipping 24 matching lines @@
 
   void PrintTo(StringStream* stream);
   void PrintToStd();
 
  private:
   explicit HEnvironment(const HEnvironment* other);
 
   // True if index is included in the expression stack part of the environment.
   bool HasExpressionAt(int index) const;
 
-  bool ExpressionStackIsEmpty() const;
-
   void Initialize(int parameter_count, int local_count, int stack_height);
   void Initialize(const HEnvironment* other);
 
   // Map a variable to an environment index.  Parameter indices are shifted
   // by 1 (receiver is parameter index -1 but environment index 0).
   // Stack-allocated local indices are shifted by the number of parameters.
   int IndexFor(Variable* variable) const {
     Slot* slot = variable->AsSlot();
     ASSERT(slot != NULL && slot->IsStackAllocated());
-    int shift = (slot->type() == Slot::PARAMETER) ? 1 : parameter_count_;
+    int shift = (slot->type() == Slot::PARAMETER)
+        ? 1
+        : parameter_count_ + specials_count_;
     return slot->index() + shift;
   }
 
   Handle<JSFunction> closure_;
-  // Value array [parameters] [locals] [temporaries].
+  // Value array [parameters] [specials] [locals] [temporaries].
   ZoneList<HValue*> values_;
   ZoneList<int> assigned_variables_;
   int parameter_count_;
+  int specials_count_;
   int local_count_;
   HEnvironment* outer_;
   int pop_count_;
   int push_count_;
   int ast_id_;
 };
 
 
 class HGraphBuilder;
 
@@ skipping 713 matching lines @@
   const char* filename_;
   HeapStringAllocator string_allocator_;
   StringStream trace_;
   int indent_;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_HYDROGEN_H_