Merge bleeding_edge from version 2.1.3 up to revision 4205...

src/ast.h

 // Copyright 2010 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 85 matching lines @@
 
 #define AST_NODE_LIST(V)                        \
   V(Declaration)                                \
   STATEMENT_NODE_LIST(V)                        \
   EXPRESSION_NODE_LIST(V)
 
 // Forward declarations
 class TargetCollector;
 class MaterializedLiteral;
 class DefinitionInfo;
+class BitVector;
 
 #define DEF_FORWARD_DECLARATION(type) class type;
 AST_NODE_LIST(DEF_FORWARD_DECLARATION)
 #undef DEF_FORWARD_DECLARATION
 
 
 // Typedef only introduced to avoid unreadable code.
 // Please do appreciate the required space in "> >".
 typedef ZoneList<Handle<String> > ZoneStringList;
 typedef ZoneList<Handle<Object> > ZoneObjectList;
 
 
 class AstNode: public ZoneObject {
  public:
   static const int kNoNumber = -1;
 
   AstNode() : num_(kNoNumber) {}
+
+  explicit AstNode(AstNode* other);
+
   virtual ~AstNode() { }
   virtual void Accept(AstVisitor* v) = 0;
 
   // Type testing & conversion.
   virtual Statement* AsStatement() { return NULL; }
+  virtual Block* AsBlock() { return NULL; }
   virtual ExpressionStatement* AsExpressionStatement() { return NULL; }
   virtual EmptyStatement* AsEmptyStatement() { return NULL; }
   virtual Expression* AsExpression() { return NULL; }
   virtual Literal* AsLiteral() { return NULL; }
   virtual Slot* AsSlot() { return NULL; }
   virtual VariableProxy* AsVariableProxy() { return NULL; }
   virtual Property* AsProperty() { return NULL; }
   virtual Call* AsCall() { return NULL; }
   virtual TargetCollector* AsTargetCollector() { return NULL; }
   virtual BreakableStatement* AsBreakableStatement() { return NULL; }
   virtual IterationStatement* AsIterationStatement() { return NULL; }
+  virtual ForStatement* AsForStatement() { return NULL; }
   virtual UnaryOperation* AsUnaryOperation() { return NULL; }
+  virtual CountOperation* AsCountOperation() { return NULL; }
   virtual BinaryOperation* AsBinaryOperation() { return NULL; }
   virtual Assignment* AsAssignment() { return NULL; }
   virtual FunctionLiteral* AsFunctionLiteral() { return NULL; }
   virtual MaterializedLiteral* AsMaterializedLiteral() { return NULL; }
   virtual ObjectLiteral* AsObjectLiteral() { return NULL; }
   virtual ArrayLiteral* AsArrayLiteral() { return NULL; }
   virtual CompareOperation* AsCompareOperation() { return NULL; }
 
   int num() { return num_; }
   void set_num(int n) { num_ = n; }
 
  private:
   // Support for ast node numbering.
   int num_;
 };
 
 
 class Statement: public AstNode {
  public:
   Statement() : statement_pos_(RelocInfo::kNoPosition) {}
 
+  explicit Statement(Statement* other);
+
   virtual Statement* AsStatement()  { return this; }
   virtual ReturnStatement* AsReturnStatement() { return NULL; }
 
+  virtual Assignment* StatementAsSimpleAssignment() { return NULL; }
+  virtual CountOperation* StatementAsCountOperation() { return NULL; }
+
   bool IsEmpty() { return AsEmptyStatement() != NULL; }
 
   void set_statement_pos(int statement_pos) { statement_pos_ = statement_pos; }
   int statement_pos() const { return statement_pos_; }
 
  private:
   int statement_pos_;
 };
 
 
@@ skipping 10 matching lines @@
     // Evaluated for control flow (and side effects).
     kTest,
     // Evaluated for control flow and side effects.  Value is also
     // needed if true.
     kValueTest,
     // Evaluated for control flow and side effects.  Value is also
     // needed if false.
     kTestValue
   };
 
-  Expression()
-      : bitfields_(0),
-        def_(NULL),
-        defined_vars_(NULL) {}
+  Expression() : bitfields_(0) {}
+
+  explicit Expression(Expression* other);
 
   virtual Expression* AsExpression()  { return this; }
 
   virtual bool IsValidLeftHandSide() { return false; }
 
+  virtual Variable* AssignedVar() { return NULL; }
+
   // Symbols that cannot be parsed as array indices are considered property
   // names.  We do not treat symbols that can be array indexes as property
   // names because [] for string objects is handled only by keyed ICs.
   virtual bool IsPropertyName() { return false; }
 
   // True if the expression does not have (evaluated) subexpressions.
   // Function literals are leaves because their subexpressions are not
   // evaluated.
   virtual bool IsLeaf() { return false; }
 
   // True if the expression has no side effects and is safe to
   // evaluate out of order.
   virtual bool IsTrivial() { return false; }
 
+  // True if the expression always has one of the non-Object JS types
+  // (Undefined, Null, Boolean, String, or Number).
+  virtual bool IsPrimitive() = 0;
+
   // Mark the expression as being compiled as an expression
   // statement. This is used to transform postfix increments to
   // (faster) prefix increments.
   virtual void MarkAsStatement() { /* do nothing */ }
 
   // Static type information for this expression.
   StaticType* type() { return &type_; }
 
-  // Data flow information.
-  DefinitionInfo* var_def() { return def_; }
-  void set_var_def(DefinitionInfo* def) { def_ = def; }
-
-  ZoneList<DefinitionInfo*>* defined_vars() { return defined_vars_; }
-  void set_defined_vars(ZoneList<DefinitionInfo*>* defined_vars) {
-    defined_vars_ = defined_vars;
-  }
-
   // AST analysis results
 
   // True if the expression rooted at this node can be compiled by the
   // side-effect free compiler.
   bool side_effect_free() { return SideEffectFreeField::decode(bitfields_); }
   void set_side_effect_free(bool is_side_effect_free) {
     bitfields_ &= ~SideEffectFreeField::mask();
     bitfields_ |= SideEffectFreeField::encode(is_side_effect_free);
   }
 
+  // Will the use of this expression treat -0 the same as 0 in all cases?
+  // If so, we can return 0 instead of -0 if we want to, to optimize code.
+  bool no_negative_zero() { return NoNegativeZeroField::decode(bitfields_); }
+  void set_no_negative_zero(bool no_negative_zero) {
+    bitfields_ &= ~NoNegativeZeroField::mask();
+    bitfields_ |= NoNegativeZeroField::encode(no_negative_zero);
+  }
+
   // Will ToInt32 (ECMA 262-3 9.5) or ToUint32 (ECMA 262-3 9.6)
   // be applied to the value of this expression?
   // If so, we may be able to optimize the calculation of the value.
   bool to_int32() { return ToInt32Field::decode(bitfields_); }
   void set_to_int32(bool to_int32) {
     bitfields_ &= ~ToInt32Field::mask();
     bitfields_ |= ToInt32Field::encode(to_int32);
   }
 
+  // How many bitwise logical or shift operators are used in this expression?
+  int num_bit_ops() { return NumBitOpsField::decode(bitfields_); }
+  void set_num_bit_ops(int num_bit_ops) {
+    bitfields_ &= ~NumBitOpsField::mask();
+    num_bit_ops = Min(num_bit_ops, kMaxNumBitOps);
+    bitfields_ |= NumBitOpsField::encode(num_bit_ops);
+  }
 
  private:
+  static const int kMaxNumBitOps = (1 << 5) - 1;
+
   uint32_t bitfields_;
   StaticType type_;
 
-  DefinitionInfo* def_;
-  ZoneList<DefinitionInfo*>* defined_vars_;
-
   // Using template BitField<type, start, size>.
   class SideEffectFreeField : public BitField<bool, 0, 1> {};
-  class ToInt32Field : public BitField<bool, 1, 1> {};
+  class NoNegativeZeroField : public BitField<bool, 1, 1> {};
+  class ToInt32Field : public BitField<bool, 2, 1> {};
+  class NumBitOpsField : public BitField<int, 3, 5> {};
 };
 
 
 /**
  * A sentinel used during pre parsing that represents some expression
  * that is a valid left hand side without having to actually build
  * the expression.
  */
 class ValidLeftHandSideSentinel: public Expression {
  public:
   virtual bool IsValidLeftHandSide() { return true; }
   virtual void Accept(AstVisitor* v) { UNREACHABLE(); }
   static ValidLeftHandSideSentinel* instance() { return &instance_; }
+
+  virtual bool IsPrimitive() {
+    UNREACHABLE();
+    return false;
+  }
+
  private:
   static ValidLeftHandSideSentinel instance_;
 };
 
 
 class BreakableStatement: public Statement {
  public:
   enum Type {
     TARGET_FOR_ANONYMOUS,
     TARGET_FOR_NAMED_ONLY
@@ skipping 11 matching lines @@
 
   // Testers.
   bool is_target_for_anonymous() const { return type_ == TARGET_FOR_ANONYMOUS; }
 
  protected:
   BreakableStatement(ZoneStringList* labels, Type type)
       : labels_(labels), type_(type) {
     ASSERT(labels == NULL || labels->length() > 0);
   }
 
+  explicit BreakableStatement(BreakableStatement* other);
+
  private:
   ZoneStringList* labels_;
   Type type_;
   BreakTarget break_target_;
 };
 
 
 class Block: public BreakableStatement {
  public:
   Block(ZoneStringList* labels, int capacity, bool is_initializer_block)
       : BreakableStatement(labels, TARGET_FOR_NAMED_ONLY),
         statements_(capacity),
         is_initializer_block_(is_initializer_block) { }
 
+  // Construct a clone initialized from the original block and
+  // a deep copy of all statements of the original block.
+  Block(Block* other, ZoneList<Statement*>* statements);
+
   virtual void Accept(AstVisitor* v);
 
+  virtual Block* AsBlock() { return this; }
+
+  virtual Assignment* StatementAsSimpleAssignment() {
+    if (statements_.length() != 1) return NULL;
+    return statements_[0]->StatementAsSimpleAssignment();
+  }
+
+  virtual CountOperation* StatementAsCountOperation() {
+    if (statements_.length() != 1) return NULL;
+    return statements_[0]->StatementAsCountOperation();
+  }
+
   void AddStatement(Statement* statement) { statements_.Add(statement); }
 
   ZoneList<Statement*>* statements() { return &statements_; }
   bool is_initializer_block() const  { return is_initializer_block_; }
 
  private:
   ZoneList<Statement*> statements_;
   bool is_initializer_block_;
 };
 
@@ skipping 21 matching lines @@
   FunctionLiteral* fun_;
 };
 
 
 class IterationStatement: public BreakableStatement {
  public:
   // Type testing & conversion.
   virtual IterationStatement* AsIterationStatement() { return this; }
 
   Statement* body() const { return body_; }
+  void set_body(Statement* stmt) { body_ = stmt; }
 
   // Code generation
   BreakTarget* continue_target()  { return &continue_target_; }
 
  protected:
   explicit IterationStatement(ZoneStringList* labels)
       : BreakableStatement(labels, TARGET_FOR_ANONYMOUS), body_(NULL) { }
 
+  // Construct a clone initialized from  original and
+  // a deep copy of the original body.
+  IterationStatement(IterationStatement* other, Statement* body);
+
   void Initialize(Statement* body) {
     body_ = body;
   }
 
  private:
   Statement* body_;
   BreakTarget continue_target_;
 };
 
 
@@ skipping 52 matching lines @@
 };
 
 
 class ForStatement: public IterationStatement {
  public:
   explicit ForStatement(ZoneStringList* labels)
       : IterationStatement(labels),
         init_(NULL),
         cond_(NULL),
         next_(NULL),
-        may_have_function_literal_(true) {
-  }
+        may_have_function_literal_(true),
+        loop_variable_(NULL),
+        peel_this_loop_(false) {}
+
+  // Construct a for-statement initialized from another for-statement
+  // and deep copies of all parts of the original statement.
+  ForStatement(ForStatement* other,
+               Statement* init,
+               Expression* cond,
+               Statement* next,
+               Statement* body);
+
+  virtual ForStatement* AsForStatement() { return this; }
 
   void Initialize(Statement* init,
                   Expression* cond,
                   Statement* next,
                   Statement* body) {
     IterationStatement::Initialize(body);
     init_ = init;
     cond_ = cond;
     next_ = next;
   }
 
   virtual void Accept(AstVisitor* v);
 
   Statement* init() const  { return init_; }
+  void set_init(Statement* stmt) { init_ = stmt; }
   Expression* cond() const  { return cond_; }
+  void set_cond(Expression* expr) { cond_ = expr; }
   Statement* next() const  { return next_; }
+  void set_next(Statement* stmt) { next_ = stmt; }
   bool may_have_function_literal() const {
     return may_have_function_literal_;
   }
 
+  bool is_fast_smi_loop() { return loop_variable_ != NULL; }
+  Variable* loop_variable() { return loop_variable_; }
+  void set_loop_variable(Variable* var) { loop_variable_ = var; }
+
+  bool peel_this_loop() { return peel_this_loop_; }
+  void set_peel_this_loop(bool b) { peel_this_loop_ = b; }
+
  private:
   Statement* init_;
   Expression* cond_;
   Statement* next_;
   // True if there is a function literal subexpression in the condition.
   bool may_have_function_literal_;
+  Variable* loop_variable_;
+  bool peel_this_loop_;
 
   friend class AstOptimizer;
 };
 
 
 class ForInStatement: public IterationStatement {
  public:
   explicit ForInStatement(ZoneStringList* labels)
       : IterationStatement(labels), each_(NULL), enumerable_(NULL) { }
 
@@ skipping 12 matching lines @@
   Expression* each_;
   Expression* enumerable_;
 };
 
 
 class ExpressionStatement: public Statement {
  public:
   explicit ExpressionStatement(Expression* expression)
       : expression_(expression) { }
 
+  // Construct an expression statement initialized from another
+  // expression statement and a deep copy of the original expression.
+  ExpressionStatement(ExpressionStatement* other, Expression* expression);
+
   virtual void Accept(AstVisitor* v);
 
   // Type testing & conversion.
   virtual ExpressionStatement* AsExpressionStatement() { return this; }
 
+  virtual Assignment* StatementAsSimpleAssignment();
+  virtual CountOperation* StatementAsCountOperation();
+
   void set_expression(Expression* e) { expression_ = e; }
   Expression* expression() { return expression_; }
 
  private:
   Expression* expression_;
 };
 
 
 class ContinueStatement: public Statement {
  public:
@@ skipping 114 matching lines @@
 // given if-statement has a then- or an else-part containing code.
 class IfStatement: public Statement {
  public:
   IfStatement(Expression* condition,
               Statement* then_statement,
               Statement* else_statement)
       : condition_(condition),
         then_statement_(then_statement),
         else_statement_(else_statement) { }
 
+  // Construct an if-statement initialized from another if-statement
+  // and deep copies of all parts of the original.
+  IfStatement(IfStatement* other,
+              Expression* condition,
+              Statement* then_statement,
+              Statement* else_statement);
+
   virtual void Accept(AstVisitor* v);
 
   bool HasThenStatement() const { return !then_statement()->IsEmpty(); }
   bool HasElseStatement() const { return !else_statement()->IsEmpty(); }
 
   Expression* condition() const { return condition_; }
   Statement* then_statement() const { return then_statement_; }
+  void set_then_statement(Statement* stmt) { then_statement_ = stmt; }
   Statement* else_statement() const { return else_statement_; }
+  void set_else_statement(Statement* stmt) { else_statement_ = stmt; }
 
  private:
   Expression* condition_;
   Statement* then_statement_;
   Statement* else_statement_;
 };
 
 
 // NOTE: TargetCollectors are represented as nodes to fit in the target
 // stack in the compiler; this should probably be reworked.
@@ skipping 74 matching lines @@
 
 
 class DebuggerStatement: public Statement {
  public:
   virtual void Accept(AstVisitor* v);
 };
 
 
 class EmptyStatement: public Statement {
  public:
+  EmptyStatement() {}
+
+  explicit EmptyStatement(EmptyStatement* other);
+
   virtual void Accept(AstVisitor* v);
 
   // Type testing & conversion.
   virtual EmptyStatement* AsEmptyStatement() { return this; }
 };
 
 
 class Literal: public Expression {
  public:
   explicit Literal(Handle<Object> handle) : handle_(handle) { }
@@ skipping 11 matching lines @@
   virtual bool IsPropertyName() {
     if (handle_->IsSymbol()) {
       uint32_t ignored;
       return !String::cast(*handle_)->AsArrayIndex(&ignored);
     }
     return false;
   }
 
   virtual bool IsLeaf() { return true; }
   virtual bool IsTrivial() { return true; }
+  virtual bool IsPrimitive();
 
   // Identity testers.
   bool IsNull() const { return handle_.is_identical_to(Factory::null_value()); }
   bool IsTrue() const { return handle_.is_identical_to(Factory::true_value()); }
   bool IsFalse() const {
     return handle_.is_identical_to(Factory::false_value());
   }
 
   Handle<Object> handle() const { return handle_; }
 
@@ skipping 55 matching lines @@
    private:
     Literal* key_;
     Expression* value_;
     Kind kind_;
   };
 
   ObjectLiteral(Handle<FixedArray> constant_properties,
                 ZoneList<Property*>* properties,
                 int literal_index,
                 bool is_simple,
+                bool fast_elements,
                 int depth)
       : MaterializedLiteral(literal_index, is_simple, depth),
         constant_properties_(constant_properties),
-        properties_(properties) {}
+        properties_(properties),
+        fast_elements_(fast_elements) {}
 
   virtual ObjectLiteral* AsObjectLiteral() { return this; }
   virtual void Accept(AstVisitor* v);
 
   virtual bool IsLeaf() { return properties()->is_empty(); }
 
+  virtual bool IsPrimitive();
+
   Handle<FixedArray> constant_properties() const {
     return constant_properties_;
   }
   ZoneList<Property*>* properties() const { return properties_; }
 
+  bool fast_elements() const { return fast_elements_; }
+
  private:
   Handle<FixedArray> constant_properties_;
   ZoneList<Property*>* properties_;
+  bool fast_elements_;
 };
 
 
 // Node for capturing a regexp literal.
 class RegExpLiteral: public MaterializedLiteral {
  public:
   RegExpLiteral(Handle<String> pattern,
                 Handle<String> flags,
                 int literal_index)
       : MaterializedLiteral(literal_index, false, 1),
         pattern_(pattern),
         flags_(flags) {}
 
   virtual void Accept(AstVisitor* v);
 
   virtual bool IsLeaf() { return true; }
 
+  virtual bool IsPrimitive();
+
   Handle<String> pattern() const { return pattern_; }
   Handle<String> flags() const { return flags_; }
 
  private:
   Handle<String> pattern_;
   Handle<String> flags_;
 };
 
 // An array literal has a literals object that is used
 // for minimizing the work when constructing it at runtime.
 class ArrayLiteral: public MaterializedLiteral {
  public:
   ArrayLiteral(Handle<FixedArray> constant_elements,
                ZoneList<Expression*>* values,
                int literal_index,
                bool is_simple,
                int depth)
       : MaterializedLiteral(literal_index, is_simple, depth),
         constant_elements_(constant_elements),
         values_(values) {}
 
   virtual void Accept(AstVisitor* v);
   virtual ArrayLiteral* AsArrayLiteral() { return this; }
 
   virtual bool IsLeaf() { return values()->is_empty(); }
 
+  virtual bool IsPrimitive();
+
   Handle<FixedArray> constant_elements() const { return constant_elements_; }
   ZoneList<Expression*>* values() const { return values_; }
 
  private:
   Handle<FixedArray> constant_elements_;
   ZoneList<Expression*>* values_;
 };
 
 
 // Node for constructing a context extension object for a catch block.
 // The catch context extension object has one property, the catch
 // variable, which should be DontDelete.
 class CatchExtensionObject: public Expression {
  public:
   CatchExtensionObject(Literal* key, VariableProxy* value)
       : key_(key), value_(value) {
   }
 
   virtual void Accept(AstVisitor* v);
 
+  virtual bool IsPrimitive();
+
   Literal* key() const { return key_; }
   VariableProxy* value() const { return value_; }
 
  private:
   Literal* key_;
   VariableProxy* value_;
 };
 
 
 class VariableProxy: public Expression {
@@ skipping 14 matching lines @@
     return var_ == NULL ? true : var_->IsValidLeftHandSide();
   }
 
   virtual bool IsLeaf() {
     ASSERT(var_ != NULL);  // Variable must be resolved.
     return var()->is_global() || var()->rewrite()->IsLeaf();
   }
 
   // Reading from a mutable variable is a side effect, but 'this' is
   // immutable.
-  virtual bool IsTrivial() { return is_this(); }
+  virtual bool IsTrivial() { return is_trivial_; }
+
+  virtual bool IsPrimitive();
 
   bool IsVariable(Handle<String> n) {
     return !is_this() && name().is_identical_to(n);
   }
 
   bool IsArguments() {
     Variable* variable = AsVariable();
     return (variable == NULL) ? false : variable->is_arguments();
   }
 
   Handle<String> name() const  { return name_; }
   Variable* var() const  { return var_; }
   bool is_this() const  { return is_this_; }
   bool inside_with() const  { return inside_with_; }
+  bool is_trivial() { return is_trivial_; }
+  void set_is_trivial(bool b) { is_trivial_ = b; }
+
+  BitVector* reaching_definitions() { return reaching_definitions_; }
+  void set_reaching_definitions(BitVector* rd) { reaching_definitions_ = rd; }
 
   // Bind this proxy to the variable var.
   void BindTo(Variable* var);
 
  protected:
   Handle<String> name_;
   Variable* var_;  // resolved variable, or NULL
   bool is_this_;
   bool inside_with_;
+  bool is_trivial_;
+  BitVector* reaching_definitions_;
 
   VariableProxy(Handle<String> name, bool is_this, bool inside_with);
   explicit VariableProxy(bool is_this);
 
   friend class Scope;
 };
 
 
 class VariableProxySentinel: public VariableProxy {
  public:
   virtual bool IsValidLeftHandSide() { return !is_this(); }
   static VariableProxySentinel* this_proxy() { return &this_proxy_; }
   static VariableProxySentinel* identifier_proxy() {
     return &identifier_proxy_;
   }
 
+  virtual bool IsPrimitive() {
+    UNREACHABLE();
+    return false;
+  }
+
  private:
   explicit VariableProxySentinel(bool is_this) : VariableProxy(is_this) { }
   static VariableProxySentinel this_proxy_;
   static VariableProxySentinel identifier_proxy_;
 };
 
 
 class Slot: public Expression {
  public:
   enum Type {
@@ skipping 23 matching lines @@
     ASSERT(var != NULL);
   }
 
   virtual void Accept(AstVisitor* v);
 
   // Type testing & conversion
   virtual Slot* AsSlot() { return this; }
 
   virtual bool IsLeaf() { return true; }
 
+  virtual bool IsPrimitive() {
+    UNREACHABLE();
+    return false;
+  }
+
   bool IsStackAllocated() { return type_ == PARAMETER || type_ == LOCAL; }
 
   // Accessors
   Variable* var() const { return var_; }
   Type type() const { return type_; }
   int index() const { return index_; }
   bool is_arguments() const { return var_->is_arguments(); }
 
  private:
   Variable* var_;
   Type type_;
   int index_;
 };
 
 
 class Property: public Expression {
  public:
   // Synthetic properties are property lookups introduced by the system,
   // to objects that aren't visible to the user. Function calls to synthetic
   // properties should use the global object as receiver, not the base object
   // of the resolved Reference.
   enum Type { NORMAL, SYNTHETIC };
   Property(Expression* obj, Expression* key, int pos, Type type = NORMAL)
       : obj_(obj), key_(key), pos_(pos), type_(type) { }
 
+  Property(Property* other, Expression* obj, Expression* key);
+
   virtual void Accept(AstVisitor* v);
 
   // Type testing & conversion
   virtual Property* AsProperty() { return this; }
 
   virtual bool IsValidLeftHandSide() { return true; }
 
+  virtual bool IsPrimitive();
+
   Expression* obj() const { return obj_; }
   Expression* key() const { return key_; }
   int position() const { return pos_; }
   bool is_synthetic() const { return type_ == SYNTHETIC; }
 
   // Returns a property singleton property access on 'this'.  Used
   // during preparsing.
   static Property* this_property() { return &this_property_; }
 
  private:
   Expression* obj_;
   Expression* key_;
   int pos_;
   Type type_;
 
   // Dummy property used during preparsing.
   static Property this_property_;
 };
 
 
 class Call: public Expression {
  public:
   Call(Expression* expression, ZoneList<Expression*>* arguments, int pos)
       : expression_(expression), arguments_(arguments), pos_(pos) { }
 
+  Call(Call* other, Expression* expression, ZoneList<Expression*>* arguments);
+
   virtual void Accept(AstVisitor* v);
 
   // Type testing and conversion.
   virtual Call* AsCall() { return this; }
 
+  virtual bool IsPrimitive();
+
   Expression* expression() const { return expression_; }
   ZoneList<Expression*>* arguments() const { return arguments_; }
   int position() { return pos_; }
 
   static Call* sentinel() { return &sentinel_; }
 
  private:
   Expression* expression_;
   ZoneList<Expression*>* arguments_;
   int pos_;
 
   static Call sentinel_;
 };
 
 
 class CallNew: public Expression {
  public:
   CallNew(Expression* expression, ZoneList<Expression*>* arguments, int pos)
       : expression_(expression), arguments_(arguments), pos_(pos) { }
 
   virtual void Accept(AstVisitor* v);
 
+  virtual bool IsPrimitive();
+
   Expression* expression() const { return expression_; }
   ZoneList<Expression*>* arguments() const { return arguments_; }
   int position() { return pos_; }
 
  private:
   Expression* expression_;
   ZoneList<Expression*>* arguments_;
   int pos_;
 };
 
 
 // The CallRuntime class does not represent any official JavaScript
 // language construct. Instead it is used to call a C or JS function
 // with a set of arguments. This is used from the builtins that are
 // implemented in JavaScript (see "v8natives.js").
 class CallRuntime: public Expression {
  public:
   CallRuntime(Handle<String> name,
               Runtime::Function* function,
               ZoneList<Expression*>* arguments)
       : name_(name), function_(function), arguments_(arguments) { }
 
   virtual void Accept(AstVisitor* v);
 
+  virtual bool IsPrimitive();
+
   Handle<String> name() const { return name_; }
   Runtime::Function* function() const { return function_; }
   ZoneList<Expression*>* arguments() const { return arguments_; }
   bool is_jsruntime() const { return function_ == NULL; }
 
  private:
   Handle<String> name_;
   Runtime::Function* function_;
   ZoneList<Expression*>* arguments_;
 };
 
 
 class UnaryOperation: public Expression {
  public:
   UnaryOperation(Token::Value op, Expression* expression)
       : op_(op), expression_(expression) {
     ASSERT(Token::IsUnaryOp(op));
   }
 
+  UnaryOperation(UnaryOperation* other, Expression* expression);
+
   virtual void Accept(AstVisitor* v);
 
   // Type testing & conversion
   virtual UnaryOperation* AsUnaryOperation() { return this; }
 
+  virtual bool IsPrimitive();
+
   Token::Value op() const { return op_; }
   Expression* expression() const { return expression_; }
 
  private:
   Token::Value op_;
   Expression* expression_;
 };
 
 
 class BinaryOperation: public Expression {
  public:
   BinaryOperation(Token::Value op, Expression* left, Expression* right)
       : op_(op), left_(left), right_(right) {
     ASSERT(Token::IsBinaryOp(op));
   }
 
+  BinaryOperation(BinaryOperation* other, Expression* left, Expression* right);
+
   virtual void Accept(AstVisitor* v);
 
   // Type testing & conversion
   virtual BinaryOperation* AsBinaryOperation() { return this; }
 
+  virtual bool IsPrimitive();
+
   // True iff the result can be safely overwritten (to avoid allocation).
   // False for operations that can return one of their operands.
   bool ResultOverwriteAllowed() {
     switch (op_) {
       case Token::COMMA:
       case Token::OR:
       case Token::AND:
         return false;
       case Token::BIT_OR:
       case Token::BIT_XOR:
@@ skipping 24 matching lines @@
 };
 
 
 class CountOperation: public Expression {
  public:
   CountOperation(bool is_prefix, Token::Value op, Expression* expression)
       : is_prefix_(is_prefix), op_(op), expression_(expression) {
     ASSERT(Token::IsCountOp(op));
   }
 
+  CountOperation(CountOperation* other, Expression* expression);
+
   virtual void Accept(AstVisitor* v);
 
+  virtual CountOperation* AsCountOperation() { return this; }
+
+  virtual Variable* AssignedVar() {
+    return expression()->AsVariableProxy()->AsVariable();
+  }
+
+  virtual bool IsPrimitive();
+
   bool is_prefix() const { return is_prefix_; }
   bool is_postfix() const { return !is_prefix_; }
   Token::Value op() const { return op_; }
   Token::Value binary_op() {
     return op_ == Token::INC ? Token::ADD : Token::SUB;
   }
   Expression* expression() const { return expression_; }
 
   virtual void MarkAsStatement() { is_prefix_ = true; }
 
  private:
   bool is_prefix_;
   Token::Value op_;
   Expression* expression_;
 };
 
 
 class CompareOperation: public Expression {
  public:
   CompareOperation(Token::Value op, Expression* left, Expression* right)
       : op_(op), left_(left), right_(right), is_for_loop_condition_(false) {
     ASSERT(Token::IsCompareOp(op));
   }
 
+  CompareOperation(CompareOperation* other,
+                   Expression* left,
+                   Expression* right);
+
   virtual void Accept(AstVisitor* v);
 
+  virtual bool IsPrimitive();
+
   Token::Value op() const { return op_; }
   Expression* left() const { return left_; }
   Expression* right() const { return right_; }
 
   // Accessors for flag whether this compare operation is hanging of a for loop.
   bool is_for_loop_condition() const { return is_for_loop_condition_; }
   void set_is_for_loop_condition() { is_for_loop_condition_ = true; }
 
   // Type testing & conversion
   virtual CompareOperation* AsCompareOperation() { return this; }
@@ skipping 10 matching lines @@
  public:
   Conditional(Expression* condition,
               Expression* then_expression,
               Expression* else_expression)
       : condition_(condition),
         then_expression_(then_expression),
         else_expression_(else_expression) { }
 
   virtual void Accept(AstVisitor* v);
 
+  virtual bool IsPrimitive();
+
   Expression* condition() const { return condition_; }
   Expression* then_expression() const { return then_expression_; }
   Expression* else_expression() const { return else_expression_; }
 
  private:
   Expression* condition_;
   Expression* then_expression_;
   Expression* else_expression_;
 };
 
 
 class Assignment: public Expression {
  public:
   Assignment(Token::Value op, Expression* target, Expression* value, int pos)
       : op_(op), target_(target), value_(value), pos_(pos),
         block_start_(false), block_end_(false) {
     ASSERT(Token::IsAssignmentOp(op));
   }
 
+  Assignment(Assignment* other, Expression* target, Expression* value);
+
   virtual void Accept(AstVisitor* v);
   virtual Assignment* AsAssignment() { return this; }
 
+  virtual bool IsPrimitive();
+
+  Assignment* AsSimpleAssignment() { return !is_compound() ? this : NULL; }
+
+  virtual Variable* AssignedVar() {
+    return target()->AsVariableProxy()->AsVariable();
+  }
+
   Token::Value binary_op() const;
 
   Token::Value op() const { return op_; }
   Expression* target() const { return target_; }
   Expression* value() const { return value_; }
   int position() { return pos_; }
   // This check relies on the definition order of token in token.h.
   bool is_compound() const { return op() > Token::ASSIGN; }
 
   // An initialization block is a series of statments of the form
@@ skipping 14 matching lines @@
   bool block_end_;
 };
 
 
 class Throw: public Expression {
  public:
   Throw(Expression* exception, int pos)
       : exception_(exception), pos_(pos) {}
 
   virtual void Accept(AstVisitor* v);
+
+  virtual bool IsPrimitive();
+
   Expression* exception() const { return exception_; }
   int position() const { return pos_; }
 
  private:
   Expression* exception_;
   int pos_;
 };
 
 
 class FunctionLiteral: public Expression {
@@ skipping 29 matching lines @@
 #endif
   }
 
   virtual void Accept(AstVisitor* v);
 
   // Type testing & conversion
   virtual FunctionLiteral* AsFunctionLiteral()  { return this; }
 
   virtual bool IsLeaf() { return true; }
 
+  virtual bool IsPrimitive();
+
   Handle<String> name() const  { return name_; }
   Scope* scope() const  { return scope_; }
   ZoneList<Statement*>* body() const  { return body_; }
   void set_function_token_position(int pos) { function_token_position_ = pos; }
   int function_token_position() const { return function_token_position_; }
   int start_position() const { return start_position_; }
   int end_position() const { return end_position_; }
   bool is_expression() const { return is_expression_; }
 
   int materialized_literal_count() { return materialized_literal_count_; }
@@ skipping 50 matching lines @@
       : boilerplate_(boilerplate) {
     ASSERT(boilerplate->IsBoilerplate());
   }
 
   Handle<JSFunction> boilerplate() const { return boilerplate_; }
 
   virtual bool IsLeaf() { return true; }
 
   virtual void Accept(AstVisitor* v);
 
+  virtual bool IsPrimitive();
+
  private:
   Handle<JSFunction> boilerplate_;
 };
 
 
 class ThisFunction: public Expression {
  public:
   virtual void Accept(AstVisitor* v);
   virtual bool IsLeaf() { return true; }
+  virtual bool IsPrimitive();
 };
 
 
 // ----------------------------------------------------------------------------
 // Regular expressions
 
 
 class RegExpVisitor BASE_EMBEDDED {
  public:
   virtual ~RegExpVisitor() { }
@@ skipping 374 matching lines @@
 #define DEF_VISIT(type)                         \
   virtual void Visit##type(type* node) = 0;
   AST_NODE_LIST(DEF_VISIT)
 #undef DEF_VISIT
 
  private:
   bool stack_overflow_;
 };
 
 
+class CopyAstVisitor : public AstVisitor {
+ public:
+  Expression* DeepCopyExpr(Expression* expr);
+
+  Statement* DeepCopyStmt(Statement* stmt);
+
+ private:
+  ZoneList<Expression*>* DeepCopyExprList(ZoneList<Expression*>* expressions);
+
+  ZoneList<Statement*>* DeepCopyStmtList(ZoneList<Statement*>* statements);
+
+  // AST node visit functions.
+#define DECLARE_VISIT(type) virtual void Visit##type(type* node);
+  AST_NODE_LIST(DECLARE_VISIT)
+#undef DECLARE_VISIT
+
+  // Holds the result of copying an expression.
+  Expression* expr_;
+  // Holds the result of copying a statement.
+  Statement* stmt_;
+};
+
 } }  // namespace v8::internal
 
 #endif  // V8_AST_H_