Infer whether a variable is assigned

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 1613 matching lines @@
   virtual bool IsValidReferenceExpression() const V8_OVERRIDE {
     return var_ == NULL ? true : var_->IsValidReference();
   }
 
   bool IsVariable(Handle<String> n) const {
     return !is_this() && name().is_identical_to(n);
   }
 
   bool IsArguments() const { return var_ != NULL && var_->is_arguments(); }
 
-  bool IsLValue() const { return is_lvalue_; }
-
   Handle<String> name() const { return name_; }
   Variable* var() const { return var_; }
   bool is_this() const { return is_this_; }
   Interface* interface() const { return interface_; }
 
-
-  void MarkAsTrivial() { is_trivial_ = true; }
-  void MarkAsLValue() { is_lvalue_ = true; }
+  bool is_assigned() const { return is_assigned_; }
+  void set_is_assigned() { is_assigned_ = true; }
 
   // Bind this proxy to the variable var. Interfaces must match.
   void BindTo(Variable* var);
 
  protected:
   VariableProxy(Zone* zone, Variable* var, int position);
 
   VariableProxy(Zone* zone,
                 Handle<String> name,
                 bool is_this,
                 Interface* interface,
                 int position);
 
   Handle<String> name_;
   Variable* var_;  // resolved variable, or NULL
   bool is_this_;
-  bool is_trivial_;
-  // True if this variable proxy is being used in an assignment
-  // or with a increment/decrement operator.
-  bool is_lvalue_;
+  bool is_assigned_;
   Interface* interface_;
 };
 
 
 class Property V8_FINAL : public Expression {
  public:
   DECLARE_NODE_TYPE(Property)
 
   virtual bool IsValidReferenceExpression() const V8_OVERRIDE { return true; }
 
@@ skipping 1678 matching lines @@
 
  private:
   Zone* zone_;
   Visitor visitor_;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_AST_H_