Squeeze the layout of variable proxy nodes.

src/ast.h

 // Copyright 2012 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_AST_H_
 #define V8_AST_H_
 
 #include "src/v8.h"
 
 #include "src/assembler.h"
@@ skipping 1618 matching lines @@
   ZoneList<Expression*>* values_;
   const BailoutId first_element_id_;
 };
 
 
 class VariableProxy FINAL : public Expression {
  public:
   DECLARE_NODE_TYPE(VariableProxy)
 
   virtual bool IsValidReferenceExpression() const OVERRIDE {
-    return var_ == NULL ? true : var_->IsValidReference();
+    return !is_resolved() || var()->IsValidReference();
   }
 
-  bool IsArguments() const { return var_ != NULL && var_->is_arguments(); }
+  bool IsArguments() const { return is_resolved() && var()->is_arguments(); }
 
-  Handle<String> name() const { return name_->string(); }
-  const AstRawString* raw_name() const { return name_; }
-  Variable* var() const { return var_; }
+  Handle<String> name() const { return raw_name()->string(); }
+  const AstRawString* raw_name() const {
+    return is_resolved() ? var_->raw_name() : raw_name_;
+  }
+
+  Variable* var() const {
+    DCHECK(is_resolved());
+    return var_;
+  }
+  void set_var(Variable* v) {
+    DCHECK(!is_resolved());
+    DCHECK_NOT_NULL(v);
+    var_ = v;
+  }
+
   bool is_this() const { return is_this_; }
-  Interface* interface() const { return interface_; }
 
   bool is_assigned() const { return is_assigned_; }
   void set_is_assigned() { is_assigned_ = true; }
 
+  bool is_resolved() const { return is_resolved_; }
+  void set_is_resolved() { is_resolved_ = true; }
+
+  Interface* interface() const { return interface_; }
+
   // Bind this proxy to the variable var. Interfaces must match.
   void BindTo(Variable* var);
 
   virtual int ComputeFeedbackSlotCount() { return FLAG_vector_ics ? 1 : 0; }
   virtual void SetFirstFeedbackSlot(int slot) {
     variable_feedback_slot_ = slot;
   }
 
   int VariableFeedbackSlot() { return variable_feedback_slot_; }
 
  protected:
   VariableProxy(Zone* zone, Variable* var, int position, IdGen* id_gen);
 
   VariableProxy(Zone* zone, const AstRawString* name, bool is_this,
                 Interface* interface, int position, IdGen* id_gen);
 
-  const AstRawString* name_;
-  Variable* var_;  // resolved variable, or NULL
-  bool is_this_;
-  bool is_assigned_;
+  union {
+    const AstRawString* raw_name_;  // if !is_resolved_
+    Variable* var_;                 // if is_resolved_
+  };
   Interface* interface_;
   int variable_feedback_slot_;
+  bool is_this_ : 1;
+  bool is_assigned_ : 1;
+  bool is_resolved_ : 1;
 };
 
 
 class Property FINAL : public Expression {
  public:
   DECLARE_NODE_TYPE(Property)
 
   virtual bool IsValidReferenceExpression() const OVERRIDE { return true; }
 
   Expression* obj() const { return obj_; }
@@ skipping 1862 matching lines @@
   Zone* zone_;
   Visitor visitor_;
   AstValueFactory* ast_value_factory_;
   AstNode::IdGen* id_gen_;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_AST_H_