webkitgtk-2.12.3webkitgtk-2.12.3

1 files changed, 680 insertions, 234 deletions

diff --git a/Source/JavaScriptCore/parser/Nodes.h b/Source/JavaScriptCore/parser/Nodes.h
index d779a178d..53519db6d 100644
--- a/Source/JavaScriptCore/parser/Nodes.h
+++ b/Source/JavaScriptCore/parser/Nodes.h
@@ -1,7 +1,7 @@
 /*
  *  Copyright (C) 1999-2000 Harri Porten (porten@kde.org)
  *  Copyright (C) 2001 Peter Kelly (pmk@post.com)
- *  Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2013 Apple Inc. All rights reserved.
+ *  Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2013, 2015 Apple Inc. All rights reserved.
  *  Copyright (C) 2007 Cameron Zwarich (cwzwarich@uwaterloo.ca)
  *  Copyright (C) 2007 Maks Orlovich
  *  Copyright (C) 2007 Eric Seidel <eric@webkit.org>
@@ -34,19 +34,22 @@
 #include "ResultType.h"
 #include "SourceCode.h"
 #include "SymbolTable.h"
+#include "VariableEnvironment.h"
 #include <wtf/MathExtras.h>
 
 namespace JSC {
 
     class ArgumentListNode;
     class BytecodeGenerator;
-    class FunctionBodyNode;
+    class FunctionMetadataNode;
+    class FunctionParameters;
     class Label;
     class PropertyListNode;
     class ReadModifyResolveNode;
     class RegisterID;
     class JSScope;
     class ScopeNode;
+    class ModuleAnalyzer;
 
     enum Operator {
         OpEqual,
@@ -76,12 +79,8 @@ namespace JSC {
     };
     inline FallThroughMode invert(FallThroughMode fallThroughMode) { return static_cast<FallThroughMode>(!fallThroughMode); }
 
-    typedef HashSet<RefPtr<StringImpl>, IdentifierRepHash> IdentifierSet;
-
     namespace DeclarationStacks {
-        enum VarAttrs { IsConstant = 1, HasInitializer = 2 };
-        typedef Vector<std::pair<Identifier, unsigned>> VarStack;
-        typedef Vector<FunctionBodyNode*> FunctionStack;
+        typedef Vector<FunctionMetadataNode*> FunctionStack;
     }
 
     struct SwitchInfo {
@@ -90,11 +89,17 @@ namespace JSC {
         SwitchType switchType;
     };
 
+    enum class AssignmentContext { 
+        DeclarationStatement, 
+        ConstDeclarationStatement, 
+        AssignmentExpression 
+    };
+
     class ParserArenaFreeable {
     public:
         // ParserArenaFreeable objects are are freed when the arena is deleted.
         // Destructors are not called. Clients must not call delete on such objects.
-        void* operator new(size_t, VM*);
+        void* operator new(size_t, ParserArena&);
     };
 
     class ParserArenaDeletable {
@@ -103,24 +108,20 @@ namespace JSC {
 
         // ParserArenaDeletable objects are deleted when the arena is deleted.
         // Clients must not call delete directly on such objects.
-        void* operator new(size_t, VM*);
+        void* operator new(size_t, ParserArena&);
     };
 
-    template <typename T>
-    struct ParserArenaData : ParserArenaDeletable {
-        T data;
-    };
-
-    class ParserArenaRefCounted : public RefCounted<ParserArenaRefCounted> {
-        WTF_FASTMALLOC_OPERATORS;
+    class ParserArenaRoot {
+        WTF_MAKE_FAST_ALLOCATED;
     protected:
-        ParserArenaRefCounted(VM*);
+        ParserArenaRoot(ParserArena&);
 
     public:
-        virtual ~ParserArenaRefCounted()
-        {
-            ASSERT(deletionHasBegun());
-        }
+        ParserArena& parserArena() { return m_arena; }
+        virtual ~ParserArenaRoot() { }
+
+    protected:
+        ParserArena m_arena;
     };
 
     class Node : public ParserArenaFreeable {
@@ -130,13 +131,17 @@ namespace JSC {
     public:
         virtual ~Node() { }
 
-        int lineNo() const { return m_position.line; }
+        int firstLine() const { return m_position.line; }
         int startOffset() const { return m_position.offset; }
+        int endOffset() const { return m_endOffset; }
         int lineStartOffset() const { return m_position.lineStartOffset; }
         const JSTextPosition& position() const { return m_position; }
+        void setEndOffset(int offset) { m_endOffset = offset; }
+        void setStartOffset(int offset) { m_position.offset = offset; }
 
     protected:
         JSTextPosition m_position;
+        int m_endOffset;
     };
 
     class ExpressionNode : public Node {
@@ -148,21 +153,27 @@ namespace JSC {
 
         virtual bool isNumber() const { return false; }
         virtual bool isString() const { return false; }
+        virtual bool isObjectLiteral() const { return false; }
+        virtual bool isArrayLiteral() const { return false; }
         virtual bool isNull() const { return false; }
         virtual bool isPure(BytecodeGenerator&) const { return false; }        
         virtual bool isConstant() const { return false; }
         virtual bool isLocation() const { return false; }
+        virtual bool isAssignmentLocation() const { return isLocation(); }
         virtual bool isResolveNode() const { return false; }
         virtual bool isBracketAccessorNode() const { return false; }
         virtual bool isDotAccessorNode() const { return false; }
-        virtual bool isDeconstructionNode() const { return false; }
+        virtual bool isDestructuringNode() const { return false; }
         virtual bool isFuncExprNode() const { return false; }
+        virtual bool isArrowFuncExprNode() const { return false; }
         virtual bool isCommaNode() const { return false; }
         virtual bool isSimpleArray() const { return false; }
         virtual bool isAdd() const { return false; }
         virtual bool isSubtract() const { return false; }
         virtual bool isBoolean() const { return false; }
         virtual bool isSpreadExpression() const { return false; }
+        virtual bool isSuperNode() const { return false; }
+        virtual bool isBytecodeIntrinsicNode() const { return false; }
 
         virtual void emitBytecodeInConditionContext(BytecodeGenerator&, Label*, Label*, FallThroughMode);
 
@@ -182,20 +193,39 @@ namespace JSC {
         virtual void emitBytecode(BytecodeGenerator&, RegisterID* destination = 0) = 0;
 
         void setLoc(unsigned firstLine, unsigned lastLine, int startOffset, int lineStartOffset);
-        unsigned firstLine() const { return lineNo(); }
         unsigned lastLine() const { return m_lastLine; }
 
+        StatementNode* next() { return m_next; }
+        void setNext(StatementNode* next) { m_next = next; }
+
         virtual bool isEmptyStatement() const { return false; }
         virtual bool isReturnNode() const { return false; }
         virtual bool isExprStatement() const { return false; }
         virtual bool isBreak() const { return false; }
         virtual bool isContinue() const { return false; }
         virtual bool isBlock() const { return false; }
+        virtual bool isFuncDeclNode() const { return false; }
+        virtual bool isModuleDeclarationNode() const { return false; }
 
     protected:
+        StatementNode* m_next;
         int m_lastLine;
     };
 
+    class VariableEnvironmentNode : public ParserArenaDeletable {
+    public:
+        VariableEnvironmentNode()
+        {
+        }
+
+        VariableEnvironmentNode(VariableEnvironment& lexicalDeclaredVariables);
+
+        VariableEnvironment& lexicalVariables() { return m_lexicalVariables; }
+
+    protected:
+        VariableEnvironment m_lexicalVariables;
+    };
+
     class ConstantNode : public ExpressionNode {
     public:
         ConstantNode(const JSTokenLocation&, ResultType);
@@ -231,16 +261,32 @@ namespace JSC {
     class NumberNode : public ConstantNode {
     public:
         NumberNode(const JSTokenLocation&, double value);
-        double value() { return m_value; }
-        void setValue(double value) { m_value = value; }
+        double value() const { return m_value; }
+        virtual bool isIntegerNode() const = 0;
+        virtual RegisterID* emitBytecode(BytecodeGenerator&, RegisterID* = 0) override final;
 
     private:
-        virtual bool isNumber() const override { return true; }
+        virtual bool isNumber() const override final { return true; }
         virtual JSValue jsValue(BytecodeGenerator&) const override { return jsNumber(m_value); }
 
         double m_value;
     };
 
+    class DoubleNode : public NumberNode {
+    public:
+        DoubleNode(const JSTokenLocation&, double value);
+
+    private:
+        virtual bool isIntegerNode() const override { return false; }
+    };
+
+    // An integer node represent a number represented as an integer (e.g. 42 instead of 42., 42.0, 42e0)
+    class IntegerNode : public DoubleNode {
+    public:
+        IntegerNode(const JSTokenLocation&, double value);
+        virtual bool isIntegerNode() const override final { return true; }
+    };
+
     class StringNode : public ConstantNode {
     public:
         StringNode(const JSTokenLocation&, const Identifier&);
@@ -252,7 +298,7 @@ namespace JSC {
 
         const Identifier& m_value;
     };
-    
+
     class ThrowableExpressionData {
     public:
         ThrowableExpressionData()
@@ -405,6 +451,74 @@ namespace JSC {
         uint16_t m_subexpressionLineStartOffset;
     };
 
+    class TemplateExpressionListNode : public ParserArenaFreeable {
+    public:
+        TemplateExpressionListNode(ExpressionNode*);
+        TemplateExpressionListNode(TemplateExpressionListNode*, ExpressionNode*);
+
+        ExpressionNode* value() { return m_node; }
+        TemplateExpressionListNode* next() { return m_next; }
+
+    private:
+        TemplateExpressionListNode* m_next { nullptr };
+        ExpressionNode* m_node { nullptr };
+    };
+
+    class TemplateStringNode : public ExpressionNode {
+    public:
+        TemplateStringNode(const JSTokenLocation&, const Identifier& cooked, const Identifier& raw);
+
+        const Identifier& cooked() { return m_cooked; }
+        const Identifier& raw() { return m_raw; }
+
+    private:
+        virtual RegisterID* emitBytecode(BytecodeGenerator&, RegisterID* = 0) override;
+
+        const Identifier& m_cooked;
+        const Identifier& m_raw;
+    };
+
+    class TemplateStringListNode : public ParserArenaFreeable {
+    public:
+        TemplateStringListNode(TemplateStringNode*);
+        TemplateStringListNode(TemplateStringListNode*, TemplateStringNode*);
+
+        TemplateStringNode* value() { return m_node; }
+        TemplateStringListNode* next() { return m_next; }
+
+    private:
+        TemplateStringListNode* m_next { nullptr };
+        TemplateStringNode* m_node { nullptr };
+    };
+
+    class TemplateLiteralNode : public ExpressionNode {
+    public:
+        TemplateLiteralNode(const JSTokenLocation&, TemplateStringListNode*);
+        TemplateLiteralNode(const JSTokenLocation&, TemplateStringListNode*, TemplateExpressionListNode*);
+
+        TemplateStringListNode* templateStrings() const { return m_templateStrings; }
+        TemplateExpressionListNode* templateExpressions() const { return m_templateExpressions; }
+
+    private:
+        virtual RegisterID* emitBytecode(BytecodeGenerator&, RegisterID* = 0) override;
+
+        TemplateStringListNode* m_templateStrings;
+        TemplateExpressionListNode* m_templateExpressions;
+    };
+
+    class TaggedTemplateNode : public ExpressionNode, public ThrowableExpressionData {
+    public:
+        TaggedTemplateNode(const JSTokenLocation&, ExpressionNode*, TemplateLiteralNode*);
+
+        TemplateLiteralNode* templateLiteral() const { return m_templateLiteral; }
+
+    private:
+        virtual RegisterID* emitBytecode(BytecodeGenerator&, RegisterID* = 0) override;
+
+        ExpressionNode* m_tag;
+        TemplateLiteralNode* m_templateLiteral;
+    };
+
     class RegExpNode : public ExpressionNode, public ThrowableExpressionData {
     public:
         RegExpNode(const JSTokenLocation&, const Identifier& pattern, const Identifier& flags);
@@ -418,7 +532,26 @@ namespace JSC {
 
     class ThisNode : public ExpressionNode {
     public:
-        ThisNode(const JSTokenLocation&);
+        ThisNode(const JSTokenLocation&, ThisTDZMode);
+
+    private:
+        virtual RegisterID* emitBytecode(BytecodeGenerator&, RegisterID* = 0) override;
+
+        bool m_shouldAlwaysEmitTDZCheck;
+    };
+
+    class SuperNode final : public ExpressionNode {
+    public:
+        SuperNode(const JSTokenLocation&);
+
+    private:
+        virtual bool isSuperNode() const override { return true; }
+        virtual RegisterID* emitBytecode(BytecodeGenerator&, RegisterID* = 0) override;
+    };
+
+    class NewTargetNode final : public ExpressionNode {
+    public:
+        NewTargetNode(const JSTokenLocation&);
 
     private:
         virtual RegisterID* emitBytecode(BytecodeGenerator&, RegisterID* = 0) override;
@@ -462,7 +595,9 @@ namespace JSC {
         ArrayNode(const JSTokenLocation&, ElementNode*);
         ArrayNode(const JSTokenLocation&, int elision, ElementNode*);
 
-        ArgumentListNode* toArgumentList(VM*, int, int) const;
+        virtual bool isArrayLiteral() const override { return true; }
+
+        ArgumentListNode* toArgumentList(ParserArena&, int, int) const;
 
         ElementNode* elements() const { ASSERT(isSimpleArray()); return m_element; }
     private:
@@ -477,23 +612,27 @@ namespace JSC {
 
     class PropertyNode : public ParserArenaFreeable {
     public:
-        enum Type { Constant = 1, Getter = 2, Setter = 4 };
+        enum Type { Constant = 1, Getter = 2, Setter = 4, Computed = 8, Shorthand = 16 };
+        enum PutType { Unknown, KnownDirect };
+
+        PropertyNode(const Identifier&, ExpressionNode*, Type, PutType, SuperBinding);
+        PropertyNode(ExpressionNode* propertyName, ExpressionNode*, Type, PutType, SuperBinding);
 
-        PropertyNode(VM*, const Identifier&, ExpressionNode*, Type);
-        PropertyNode(VM*, double, ExpressionNode*, Type);
-        PropertyNode(VM*, ExpressionNode* propertyName, ExpressionNode*, Type);
-        
         ExpressionNode* expressionName() const { return m_expression; }
         const Identifier* name() const { return m_name; }
 
-        Type type() const { return m_type; }
+        Type type() const { return static_cast<Type>(m_type); }
+        bool needsSuperBinding() const { return m_needsSuperBinding; }
+        PutType putType() const { return static_cast<PutType>(m_putType); }
 
     private:
         friend class PropertyListNode;
         const Identifier* m_name;
         ExpressionNode* m_expression;
         ExpressionNode* m_assign;
-        Type m_type;
+        unsigned m_type : 5;
+        unsigned m_needsSuperBinding : 1;
+        unsigned m_putType : 1;
     };
 
     class PropertyListNode : public ExpressionNode {
@@ -501,9 +640,10 @@ namespace JSC {
         PropertyListNode(const JSTokenLocation&, PropertyNode*);
         PropertyListNode(const JSTokenLocation&, PropertyNode*, PropertyListNode*);
 
+    private:
         virtual RegisterID* emitBytecode(BytecodeGenerator&, RegisterID* = 0) override;
+        void emitPutConstantProperty(BytecodeGenerator&, RegisterID*, PropertyNode&);
 
-    private:
         PropertyNode* m_node;
         PropertyListNode* m_next;
     };
@@ -512,6 +652,7 @@ namespace JSC {
     public:
         ObjectLiteralNode(const JSTokenLocation&);
         ObjectLiteralNode(const JSTokenLocation&, PropertyListNode*);
+        virtual bool isObjectLiteral() const override { return true; }
 
     private:
         virtual RegisterID* emitBytecode(BytecodeGenerator&, RegisterID* = 0) override;
@@ -635,7 +776,7 @@ namespace JSC {
     
     class FunctionCallBracketNode : public ExpressionNode, public ThrowableSubExpressionData {
     public:
-        FunctionCallBracketNode(const JSTokenLocation&, ExpressionNode* base, ExpressionNode* subscript, ArgumentsNode*, const JSTextPosition& divot, const JSTextPosition& divotStart, const JSTextPosition& divotEnd);
+        FunctionCallBracketNode(const JSTokenLocation&, ExpressionNode* base, ExpressionNode* subscript, bool subscriptHasAssignments, ArgumentsNode*, const JSTextPosition& divot, const JSTextPosition& divotStart, const JSTextPosition& divotEnd);
 
     private:
         virtual RegisterID* emitBytecode(BytecodeGenerator&, RegisterID* = 0) override;
@@ -643,6 +784,7 @@ namespace JSC {
         ExpressionNode* m_base;
         ExpressionNode* m_subscript;
         ArgumentsNode* m_args;
+        bool m_subscriptHasAssignments;
     };
 
     class FunctionCallDotNode : public ExpressionNode, public ThrowableSubExpressionData {
@@ -658,6 +800,37 @@ namespace JSC {
         ArgumentsNode* m_args;
     };
 
+    class BytecodeIntrinsicNode : public ExpressionNode, public ThrowableExpressionData {
+    public:
+        enum class Type {
+            Constant,
+            Function
+        };
+
+        typedef RegisterID* (BytecodeIntrinsicNode::* EmitterType)(BytecodeGenerator&, RegisterID*);
+
+        BytecodeIntrinsicNode(Type, const JSTokenLocation&, EmitterType, const Identifier&, ArgumentsNode*, const JSTextPosition& divot, const JSTextPosition& divotStart, const JSTextPosition& divotEnd);
+
+        virtual bool isBytecodeIntrinsicNode() const override { return true; }
+
+        Type type() const { return m_type; }
+        EmitterType emitter() const { return m_emitter; }
+        const Identifier& identifier() const { return m_ident; }
+
+#define JSC_DECLARE_BYTECODE_INTRINSIC_FUNCTIONS(name) RegisterID* emit_intrinsic_##name(BytecodeGenerator&, RegisterID*);
+        JSC_COMMON_BYTECODE_INTRINSIC_FUNCTIONS_EACH_NAME(JSC_DECLARE_BYTECODE_INTRINSIC_FUNCTIONS)
+        JSC_COMMON_BYTECODE_INTRINSIC_CONSTANTS_EACH_NAME(JSC_DECLARE_BYTECODE_INTRINSIC_FUNCTIONS)
+#undef JSC_DECLARE_BYTECODE_INTRINSIC_FUNCTIONS
+
+    private:
+        virtual RegisterID* emitBytecode(BytecodeGenerator&, RegisterID* = 0) override;
+
+        Type m_type;
+        EmitterType m_emitter;
+        const Identifier& m_ident;
+        ArgumentsNode* m_args;
+    };
+
     class CallFunctionCallDotNode : public FunctionCallDotNode {
     public:
         CallFunctionCallDotNode(const JSTokenLocation&, ExpressionNode* base, const Identifier&, ArgumentsNode*, const JSTextPosition& divot, const JSTextPosition& divotStart, const JSTextPosition& divotEnd);
@@ -1020,13 +1193,14 @@ namespace JSC {
 
     class AssignResolveNode : public ExpressionNode, public ThrowableExpressionData {
     public:
-        AssignResolveNode(const JSTokenLocation&, const Identifier&, ExpressionNode* right);
+        AssignResolveNode(const JSTokenLocation&, const Identifier&, ExpressionNode* right, AssignmentContext);
 
     private:
         virtual RegisterID* emitBytecode(BytecodeGenerator&, RegisterID* = 0) override;
 
         const Identifier& m_ident;
         ExpressionNode* m_right;
+        AssignmentContext m_assignmentContext;
     };
 
     class ReadModifyBracketNode : public ExpressionNode, public ThrowableSubExpressionData {
@@ -1039,7 +1213,7 @@ namespace JSC {
         ExpressionNode* m_base;
         ExpressionNode* m_subscript;
         ExpressionNode* m_right;
-        Operator m_operator : 30;
+        unsigned m_operator : 30;
         bool m_subscriptHasAssignments : 1;
         bool m_rightHasAssignments : 1;
     };
@@ -1081,7 +1255,7 @@ namespace JSC {
         ExpressionNode* m_base;
         const Identifier& m_ident;
         ExpressionNode* m_right;
-        Operator m_operator : 31;
+        unsigned m_operator : 31;
         bool m_rightHasAssignments : 1;
     };
 
@@ -1093,54 +1267,22 @@ namespace JSC {
         virtual RegisterID* emitBytecode(BytecodeGenerator&, RegisterID* = 0) override;
     };
     
-    typedef Vector<ExpressionNode*, 8> ExpressionVector;
-
-    class CommaNode : public ExpressionNode, public ParserArenaDeletable {
+    class CommaNode final : public ExpressionNode {
     public:
-        CommaNode(const JSTokenLocation&, ExpressionNode* expr1, ExpressionNode* expr2);
-
-        using ParserArenaDeletable::operator new;
+        CommaNode(const JSTokenLocation&, ExpressionNode*);
 
-        void append(ExpressionNode* expr) { ASSERT(expr); m_expressions.append(expr); }
+        void setNext(CommaNode* next) { m_next = next; }
+        CommaNode* next() { return m_next; }
 
     private:
         virtual bool isCommaNode() const override { return true; }
         virtual RegisterID* emitBytecode(BytecodeGenerator&, RegisterID* = 0) override;
 
-        ExpressionVector m_expressions;
+        ExpressionNode* m_expr;
+        CommaNode* m_next;
     };
     
-    class ConstDeclNode : public ExpressionNode {
-    public:
-        ConstDeclNode(const JSTokenLocation&, const Identifier&, ExpressionNode*);
-
-        bool hasInitializer() const { return m_init; }
-        const Identifier& ident() { return m_ident; }
-
-    private:
-        virtual RegisterID* emitBytecode(BytecodeGenerator&, RegisterID* = 0) override;
-        virtual RegisterID* emitCodeSingle(BytecodeGenerator&);
-
-        const Identifier& m_ident;
-
-    public:
-        ConstDeclNode* m_next;
-
-    private:
-        ExpressionNode* m_init;
-    };
-
-    class ConstStatementNode : public StatementNode {
-    public:
-        ConstStatementNode(const JSTokenLocation&, ConstDeclNode* next);
-
-    private:
-        virtual void emitBytecode(BytecodeGenerator&, RegisterID* = 0) override;
-
-        ConstDeclNode* m_next;
-    };
-
-    class SourceElements : public ParserArenaDeletable {
+    class SourceElements final : public ParserArenaFreeable {
     public:
         SourceElements();
 
@@ -1150,14 +1292,18 @@ namespace JSC {
         StatementNode* lastStatement() const;
 
         void emitBytecode(BytecodeGenerator&, RegisterID* destination);
+        void analyzeModule(ModuleAnalyzer&);
 
     private:
-        Vector<StatementNode*> m_statements;
+        StatementNode* m_head;
+        StatementNode* m_tail;
     };
 
-    class BlockNode : public StatementNode {
+    class BlockNode : public StatementNode, public VariableEnvironmentNode {
     public:
-        BlockNode(const JSTokenLocation&, SourceElements* = 0);
+        using ParserArenaDeletable::operator new;
+
+        BlockNode(const JSTokenLocation&, SourceElements*, VariableEnvironment&);
 
         StatementNode* singleStatement() const;
         StatementNode* lastStatement() const;
@@ -1202,15 +1348,35 @@ namespace JSC {
         ExpressionNode* m_expr;
     };
 
-    class VarStatementNode : public StatementNode {
+    class DeclarationStatement : public StatementNode {
     public:
-        VarStatementNode(const JSTokenLocation&, ExpressionNode*);
+        DeclarationStatement(const JSTokenLocation&, ExpressionNode*);
     private:
         virtual void emitBytecode(BytecodeGenerator&, RegisterID* = 0) override;
 
         ExpressionNode* m_expr;
     };
 
+    class EmptyVarExpression : public ExpressionNode {
+    public:
+        EmptyVarExpression(const JSTokenLocation&, const Identifier&);
+
+    private:
+        virtual RegisterID* emitBytecode(BytecodeGenerator&, RegisterID* = 0) override;
+
+        const Identifier& m_ident;
+    };
+
+    class EmptyLetExpression : public ExpressionNode {
+    public:
+        EmptyLetExpression(const JSTokenLocation&, const Identifier&);
+
+    private:
+        virtual RegisterID* emitBytecode(BytecodeGenerator&, RegisterID* = 0) override;
+
+        const Identifier& m_ident;
+    };
+
     class IfElseNode : public StatementNode {
     public:
         IfElseNode(const JSTokenLocation&, ExpressionNode* condition, StatementNode* ifBlock, StatementNode* elseBlock);
@@ -1247,9 +1413,11 @@ namespace JSC {
         StatementNode* m_statement;
     };
 
-    class ForNode : public StatementNode {
+    class ForNode : public StatementNode, public VariableEnvironmentNode {
     public:
-        ForNode(const JSTokenLocation&, ExpressionNode* expr1, ExpressionNode* expr2, ExpressionNode* expr3, StatementNode*);
+        using ParserArenaDeletable::operator new;
+
+        ForNode(const JSTokenLocation&, ExpressionNode* expr1, ExpressionNode* expr2, ExpressionNode* expr3, StatementNode*, VariableEnvironment&);
 
     private:
         virtual void emitBytecode(BytecodeGenerator&, RegisterID* = 0) override;
@@ -1260,12 +1428,13 @@ namespace JSC {
         StatementNode* m_statement;
     };
     
-    class DeconstructionPatternNode;
+    class DestructuringPatternNode;
     
-    class EnumerationNode : public StatementNode, public ThrowableExpressionData {
+    class EnumerationNode : public StatementNode, public ThrowableExpressionData, public VariableEnvironmentNode {
     public:
-        EnumerationNode(const JSTokenLocation&, ExpressionNode*, ExpressionNode*, StatementNode*);
-        EnumerationNode(VM*, const JSTokenLocation&, DeconstructionPatternNode*, ExpressionNode*, StatementNode*);
+        using ParserArenaDeletable::operator new;
+
+        EnumerationNode(const JSTokenLocation&, ExpressionNode*, ExpressionNode*, StatementNode*, VariableEnvironment&);
         
     protected:
         ExpressionNode* m_lexpr;
@@ -1275,17 +1444,19 @@ namespace JSC {
     
     class ForInNode : public EnumerationNode {
     public:
-        ForInNode(const JSTokenLocation&, ExpressionNode*, ExpressionNode*, StatementNode*);
-        ForInNode(VM*, const JSTokenLocation&, DeconstructionPatternNode*, ExpressionNode*, StatementNode*);
+        ForInNode(const JSTokenLocation&, ExpressionNode*, ExpressionNode*, StatementNode*, VariableEnvironment&);
 
     private:
+        RegisterID* tryGetBoundLocal(BytecodeGenerator&);
+        void emitLoopHeader(BytecodeGenerator&, RegisterID* propertyName);
+        void emitMultiLoopBytecode(BytecodeGenerator&, RegisterID* dst);
+
         virtual void emitBytecode(BytecodeGenerator&, RegisterID* = 0) override;
     };
     
     class ForOfNode : public EnumerationNode {
     public:
-        ForOfNode(const JSTokenLocation&, ExpressionNode*, ExpressionNode*, StatementNode*);
-        ForOfNode(VM*, const JSTokenLocation&, DeconstructionPatternNode*, ExpressionNode*, StatementNode*);
+        ForOfNode(const JSTokenLocation&, ExpressionNode*, ExpressionNode*, StatementNode*, VariableEnvironment&);
         
     private:
         virtual void emitBytecode(BytecodeGenerator&, RegisterID* = 0) override;
@@ -1293,7 +1464,6 @@ namespace JSC {
 
     class ContinueNode : public StatementNode, public ThrowableExpressionData {
     public:
-        ContinueNode(VM*, const JSTokenLocation&);
         ContinueNode(const JSTokenLocation&, const Identifier&);
         Label* trivialTarget(BytecodeGenerator&);
         
@@ -1306,7 +1476,6 @@ namespace JSC {
 
     class BreakNode : public StatementNode, public ThrowableExpressionData {
     public:
-        BreakNode(VM*, const JSTokenLocation&);
         BreakNode(const JSTokenLocation&, const Identifier&);
         Label* trivialTarget(BytecodeGenerator&);
         
@@ -1365,50 +1534,29 @@ namespace JSC {
         ExpressionNode* m_expr;
     };
 
-    class TryNode : public StatementNode {
+    class TryNode : public StatementNode, public VariableEnvironmentNode {
     public:
-        TryNode(const JSTokenLocation&, StatementNode* tryBlock, const Identifier& exceptionIdent, StatementNode* catchBlock, StatementNode* finallyBlock);
+        using ParserArenaDeletable::operator new;
+
+        TryNode(const JSTokenLocation&, StatementNode* tryBlock, DestructuringPatternNode* catchPattern, StatementNode* catchBlock, VariableEnvironment& catchEnvironment, StatementNode* finallyBlock);
 
     private:
         virtual void emitBytecode(BytecodeGenerator&, RegisterID* = 0) override;
 
         StatementNode* m_tryBlock;
-        const Identifier& m_exceptionIdent;
+        DestructuringPatternNode* m_catchPattern;
         StatementNode* m_catchBlock;
         StatementNode* m_finallyBlock;
     };
 
-    class ParameterNode : public ParserArenaDeletable {
-    public:
-        ParameterNode(PassRefPtr<DeconstructionPatternNode>);
-        ParameterNode(ParameterNode*, PassRefPtr<DeconstructionPatternNode>);
-
-        DeconstructionPatternNode* pattern() const { return m_pattern.get(); }
-        ParameterNode* nextParam() const { return m_next; }
-
-    private:
-        RefPtr<DeconstructionPatternNode> m_pattern;
-        ParameterNode* m_next;
-    };
-
-    class ScopeNode : public StatementNode, public ParserArenaRefCounted {
+    class ScopeNode : public StatementNode, public ParserArenaRoot, public VariableEnvironmentNode {
     public:
-        typedef DeclarationStacks::VarStack VarStack;
         typedef DeclarationStacks::FunctionStack FunctionStack;
 
-        ScopeNode(VM*, const JSTokenLocation& start, const JSTokenLocation& end, bool inStrictContext);
-        ScopeNode(VM*, const JSTokenLocation& start, const JSTokenLocation& end, const SourceCode&, SourceElements*, VarStack*, FunctionStack*, IdentifierSet&, CodeFeatures, int numConstants);
-
-        using ParserArenaRefCounted::operator new;
+        ScopeNode(ParserArena&, const JSTokenLocation& start, const JSTokenLocation& end, bool inStrictContext);
+        ScopeNode(ParserArena&, const JSTokenLocation& start, const JSTokenLocation& end, const SourceCode&, SourceElements*, VariableEnvironment&, FunctionStack&, VariableEnvironment&, CodeFeatures, int numConstants);
 
-        void destroyData()
-        {
-            m_arena.reset();
-            m_varStack.clear();
-            m_functionStack.clear();
-            m_statements = 0;
-            m_capturedVariables.clear();
-        }
+        using ParserArenaRoot::operator new;
 
         const SourceCode& source() const { return m_source; }
         const String& sourceURL() const { return m_source.provider()->url(); }
@@ -1423,17 +1571,18 @@ namespace JSC {
 
         bool usesEval() const { return m_features & EvalFeature; }
         bool usesArguments() const { return (m_features & ArgumentsFeature) && !(m_features & ShadowsArgumentsFeature); }
+        bool usesArrowFunction() const { return m_features & ArrowFunctionFeature; }
         bool modifiesParameter() const { return m_features & ModifiedParameterFeature; }
+        bool modifiesArguments() const { return m_features & (EvalFeature | ModifiedArgumentsFeature); }
         bool isStrictMode() const { return m_features & StrictModeFeature; }
         void setUsesArguments() { m_features |= ArgumentsFeature; }
         bool usesThis() const { return m_features & ThisFeature; }
-        bool needsActivationForMoreThanVariables() const { return m_features & (EvalFeature | WithFeature | CatchFeature); }
-        bool needsActivation() const { return (hasCapturedVariables()) || (m_features & (EvalFeature | WithFeature | CatchFeature)); }
-        bool hasCapturedVariables() const { return !!m_capturedVariables.size(); }
-        size_t capturedVariableCount() const { return m_capturedVariables.size(); }
-        bool captures(const Identifier& ident) { return m_capturedVariables.contains(ident.impl()); }
+        bool needsActivation() const { return (hasCapturedVariables()) || (m_features & (EvalFeature | WithFeature)); }
+        bool hasCapturedVariables() const { return m_varDeclarations.hasCapturedVariables(); }
+        bool captures(UniquedStringImpl* uid) { return m_varDeclarations.captures(uid); }
+        bool captures(const Identifier& ident) { return captures(ident.impl()); }
 
-        VarStack& varStack() { return m_varStack; }
+        VariableEnvironment& varDeclarations() { return m_varDeclarations; }
         FunctionStack& functionStack() { return m_functionStack; }
 
         int neededConstants()
@@ -1446,11 +1595,10 @@ namespace JSC {
         StatementNode* singleStatement() const;
 
         void emitStatementsBytecode(BytecodeGenerator&, RegisterID* destination);
+        
+        void analyzeModule(ModuleAnalyzer&);
 
     protected:
-        void setSource(const SourceCode& source) { m_source = source; }
-        ParserArena m_arena;
-
         int m_startLineNumber;
         unsigned m_startStartOffset;
         unsigned m_startLineStartOffset;
@@ -1458,17 +1606,15 @@ namespace JSC {
     private:
         CodeFeatures m_features;
         SourceCode m_source;
-        VarStack m_varStack;
+        VariableEnvironment m_varDeclarations;
         FunctionStack m_functionStack;
         int m_numConstants;
         SourceElements* m_statements;
-        IdentifierSet m_capturedVariables;
     };
 
     class ProgramNode : public ScopeNode {
     public:
-        static const bool isFunctionNode = false;
-        static PassRefPtr<ProgramNode> create(VM*, const JSTokenLocation& start, const JSTokenLocation& end, unsigned startColumn, unsigned endColumn, SourceElements*, VarStack*, FunctionStack*, IdentifierSet&, const SourceCode&, CodeFeatures, int numConstants);
+        ProgramNode(ParserArena&, const JSTokenLocation& start, const JSTokenLocation& end, unsigned startColumn, unsigned endColumn, SourceElements*, VariableEnvironment&, FunctionStack&, VariableEnvironment&, FunctionParameters*, const SourceCode&, CodeFeatures, int numConstants);
 
         unsigned startColumn() const { return m_startColumn; }
         unsigned endColumn() const { return m_endColumn; }
@@ -1476,18 +1622,14 @@ namespace JSC {
         static const bool scopeIsFunction = false;
 
     private:
-        ProgramNode(VM*, const JSTokenLocation& start, const JSTokenLocation& end, unsigned startColumn, unsigned endColumn, SourceElements*, VarStack*, FunctionStack*, IdentifierSet&, const SourceCode&, CodeFeatures, int numConstants);
-
         virtual void emitBytecode(BytecodeGenerator&, RegisterID* = 0) override;
-
         unsigned m_startColumn;
         unsigned m_endColumn;
     };
 
     class EvalNode : public ScopeNode {
     public:
-        static const bool isFunctionNode = false;
-        static PassRefPtr<EvalNode> create(VM*, const JSTokenLocation& start, const JSTokenLocation& end, unsigned, unsigned endColumn, SourceElements*, VarStack*, FunctionStack*, IdentifierSet&, const SourceCode&, CodeFeatures, int numConstants);
+        EvalNode(ParserArena&, const JSTokenLocation& start, const JSTokenLocation& end, unsigned startColumn, unsigned endColumn, SourceElements*, VariableEnvironment&, FunctionStack&, VariableEnvironment&, FunctionParameters*, const SourceCode&, CodeFeatures, int numConstants);
 
         ALWAYS_INLINE unsigned startColumn() const { return 0; }
         unsigned endColumn() const { return m_endColumn; }
@@ -1495,163 +1637,424 @@ namespace JSC {
         static const bool scopeIsFunction = false;
 
     private:
-        EvalNode(VM*, const JSTokenLocation& start, const JSTokenLocation& end, unsigned endColumn, SourceElements*, VarStack*, FunctionStack*, IdentifierSet&, const SourceCode&, CodeFeatures, int numConstants);
-
         virtual void emitBytecode(BytecodeGenerator&, RegisterID* = 0) override;
 
         unsigned m_endColumn;
     };
 
-    class FunctionParameters : public RefCounted<FunctionParameters> {
-        WTF_MAKE_FAST_ALLOCATED;
-        WTF_MAKE_NONCOPYABLE(FunctionParameters);
+    class ModuleProgramNode : public ScopeNode {
     public:
-        static PassRefPtr<FunctionParameters> create(ParameterNode*);
-        ~FunctionParameters();
+        ModuleProgramNode(ParserArena&, const JSTokenLocation& start, const JSTokenLocation& end, unsigned startColumn, unsigned endColumn, SourceElements*, VariableEnvironment&, FunctionStack&, VariableEnvironment&, FunctionParameters*, const SourceCode&, CodeFeatures, int numConstants);
 
-        unsigned size() const { return m_size; }
-        DeconstructionPatternNode* at(unsigned index) { ASSERT(index < m_size); return patterns()[index]; }
+        unsigned startColumn() const { return m_startColumn; }
+        unsigned endColumn() const { return m_endColumn; }
+
+        static const bool scopeIsFunction = false;
 
     private:
-        FunctionParameters(ParameterNode*, unsigned size);
+        virtual void emitBytecode(BytecodeGenerator&, RegisterID* = 0) override;
+        unsigned m_startColumn;
+        unsigned m_endColumn;
+    };
+
+    class ModuleNameNode : public Node {
+    public:
+        ModuleNameNode(const JSTokenLocation&, const Identifier& moduleName);
 
-        DeconstructionPatternNode** patterns() { return &m_storage; }
+        const Identifier& moduleName() { return m_moduleName; }
 
-        unsigned m_size;
-        DeconstructionPatternNode* m_storage;
+    private:
+        const Identifier& m_moduleName;
     };
 
-    class FunctionBodyNode : public ScopeNode {
+    class ImportSpecifierNode : public Node {
     public:
-        static const bool isFunctionNode = true;
-        static FunctionBodyNode* create(VM*, const JSTokenLocation& start, const JSTokenLocation& end, unsigned startColumn, unsigned endColumn, bool isStrictMode);
-        static PassRefPtr<FunctionBodyNode> create(VM*, const JSTokenLocation& start, const JSTokenLocation& end, unsigned startColumn, unsigned endColumn, SourceElements*, VarStack*, FunctionStack*, IdentifierSet&, const SourceCode&, CodeFeatures, int numConstants);
+        ImportSpecifierNode(const JSTokenLocation&, const Identifier& importedName, const Identifier& localName);
 
-        FunctionParameters* parameters() const { return m_parameters.get(); }
-        size_t parameterCount() const { return m_parameters->size(); }
+        const Identifier& importedName() { return m_importedName; }
+        const Identifier& localName() { return m_localName; }
 
+    private:
+        const Identifier& m_importedName;
+        const Identifier& m_localName;
+    };
+
+    class ImportSpecifierListNode : public ParserArenaDeletable {
+    public:
+        typedef Vector<ImportSpecifierNode*, 3> Specifiers;
+
+        const Specifiers& specifiers() const { return m_specifiers; }
+        void append(ImportSpecifierNode* specifier)
+        {
+            m_specifiers.append(specifier);
+        }
+
+    private:
+        Specifiers m_specifiers;
+    };
+
+    class ModuleDeclarationNode : public StatementNode {
+    public:
+        virtual void analyzeModule(ModuleAnalyzer&) = 0;
+        virtual bool isModuleDeclarationNode() const { return true; }
+
+    protected:
+        ModuleDeclarationNode(const JSTokenLocation&);
+    };
+
+    class ImportDeclarationNode : public ModuleDeclarationNode {
+    public:
+        ImportDeclarationNode(const JSTokenLocation&, ImportSpecifierListNode*, ModuleNameNode*);
+
+        ImportSpecifierListNode* specifierList() const { return m_specifierList; }
+        ModuleNameNode* moduleName() const { return m_moduleName; }
+
+    private:
+        virtual void emitBytecode(BytecodeGenerator&, RegisterID* = 0) override;
+        virtual void analyzeModule(ModuleAnalyzer&) override;
+
+        ImportSpecifierListNode* m_specifierList;
+        ModuleNameNode* m_moduleName;
+    };
+
+    class ExportAllDeclarationNode : public ModuleDeclarationNode {
+    public:
+        ExportAllDeclarationNode(const JSTokenLocation&, ModuleNameNode*);
+
+        ModuleNameNode* moduleName() const { return m_moduleName; }
+
+    private:
+        virtual void emitBytecode(BytecodeGenerator&, RegisterID* = 0) override;
+        virtual void analyzeModule(ModuleAnalyzer&) override;
+
+        ModuleNameNode* m_moduleName;
+    };
+
+    class ExportDefaultDeclarationNode : public ModuleDeclarationNode {
+    public:
+        ExportDefaultDeclarationNode(const JSTokenLocation&, StatementNode*, const Identifier& localName);
+
+        const StatementNode& declaration() const { return *m_declaration; }
+        const Identifier& localName() const { return m_localName; }
+
+    private:
+        virtual void emitBytecode(BytecodeGenerator&, RegisterID* = 0) override;
+        virtual void analyzeModule(ModuleAnalyzer&) override;
+        StatementNode* m_declaration;
+        const Identifier& m_localName;
+    };
+
+    class ExportLocalDeclarationNode : public ModuleDeclarationNode {
+    public:
+        ExportLocalDeclarationNode(const JSTokenLocation&, StatementNode*);
+
+        const StatementNode& declaration() const { return *m_declaration; }
+
+    private:
         virtual void emitBytecode(BytecodeGenerator&, RegisterID* = 0) override;
+        virtual void analyzeModule(ModuleAnalyzer&) override;
+        StatementNode* m_declaration;
+    };
+
+    class ExportSpecifierNode : public Node {
+    public:
+        ExportSpecifierNode(const JSTokenLocation&, const Identifier& localName, const Identifier& exportedName);
+
+        const Identifier& exportedName() { return m_exportedName; }
+        const Identifier& localName() { return m_localName; }
+
+    private:
+        const Identifier& m_localName;
+        const Identifier& m_exportedName;
+    };
+
+    class ExportSpecifierListNode : public ParserArenaDeletable {
+    public:
+        typedef Vector<ExportSpecifierNode*, 3> Specifiers;
 
-        void finishParsing(const SourceCode&, ParameterNode*, const Identifier&, FunctionNameIsInScopeToggle);
-        void finishParsing(PassRefPtr<FunctionParameters>, const Identifier&, FunctionNameIsInScopeToggle);
+        const Specifiers& specifiers() const { return m_specifiers; }
+        void append(ExportSpecifierNode* specifier)
+        {
+            m_specifiers.append(specifier);
+        }
+
+    private:
+        Specifiers m_specifiers;
+    };
+
+    class ExportNamedDeclarationNode : public ModuleDeclarationNode {
+    public:
+        ExportNamedDeclarationNode(const JSTokenLocation&, ExportSpecifierListNode*, ModuleNameNode*);
+
+        ExportSpecifierListNode* specifierList() const { return m_specifierList; }
+        ModuleNameNode* moduleName() const { return m_moduleName; }
+
+    private:
+        virtual void emitBytecode(BytecodeGenerator&, RegisterID* = 0) override;
+        virtual void analyzeModule(ModuleAnalyzer&) override;
+        ExportSpecifierListNode* m_specifierList;
+        ModuleNameNode* m_moduleName { nullptr };
+    };
+
+    class FunctionParameters : public ParserArenaDeletable {
+    public:
+        FunctionParameters();
+        ALWAYS_INLINE unsigned size() const { return m_patterns.size(); }
+        ALWAYS_INLINE std::pair<DestructuringPatternNode*, ExpressionNode*> at(unsigned index) { return m_patterns[index]; }
+        bool hasDefaultParameterValues() const { return m_hasDefaultParameterValues; }
+        ALWAYS_INLINE void append(DestructuringPatternNode* pattern, ExpressionNode* defaultValue) 
+        { 
+            ASSERT(pattern); 
+            m_patterns.append(std::make_pair(pattern, defaultValue));
+            if (defaultValue)
+                m_hasDefaultParameterValues = true;
+        }
+
+    private:
+
+        Vector<std::pair<DestructuringPatternNode*, ExpressionNode*>, 3> m_patterns;
+        bool m_hasDefaultParameterValues { false };
+    };
+
+    class FunctionMetadataNode final : public Node, public ParserArenaDeletable {
+    public:
+        using ParserArenaDeletable::operator new;
+
+        FunctionMetadataNode(
+            ParserArena&, const JSTokenLocation& start, const JSTokenLocation& end, 
+            unsigned startColumn, unsigned endColumn, int functionKeywordStart, 
+            int functionNameStart, int parametersStart, bool isInStrictContext, 
+            ConstructorKind, SuperBinding, unsigned, SourceParseMode, bool isArrowFunctionBodyExpression);
+
+        void finishParsing(const SourceCode&, const Identifier&, FunctionMode);
         
+        void overrideName(const Identifier& ident) { m_ident = ident; }
         const Identifier& ident() { return m_ident; }
         void setInferredName(const Identifier& inferredName) { ASSERT(!inferredName.isNull()); m_inferredName = inferredName; }
         const Identifier& inferredName() { return m_inferredName.isEmpty() ? m_ident : m_inferredName; }
 
-        bool functionNameIsInScope() { return m_functionNameIsInScopeToggle == FunctionNameIsInScope; }
-        FunctionNameIsInScopeToggle functionNameIsInScopeToggle() { return m_functionNameIsInScopeToggle; }
+        FunctionMode functionMode() { return m_functionMode; }
 
-        void setFunctionNameStart(int functionNameStart) { m_functionNameStart = functionNameStart; }
         int functionNameStart() const { return m_functionNameStart; }
+        int functionKeywordStart() const { return m_functionKeywordStart; }
+        int parametersStart() const { return m_parametersStart; }
         unsigned startColumn() const { return m_startColumn; }
         unsigned endColumn() const { return m_endColumn; }
+        unsigned parameterCount() const { return m_parameterCount; }
+        SourceParseMode parseMode() const { return m_parseMode; }
 
         void setEndPosition(JSTextPosition);
 
-        static const bool scopeIsFunction = true;
+        const SourceCode& source() const { return m_source; }
 
-    private:
-        FunctionBodyNode(VM*, const JSTokenLocation& start, const JSTokenLocation& end, unsigned startColumn, unsigned endColumn, bool inStrictContext);
-        FunctionBodyNode(VM*, const JSTokenLocation& start, const JSTokenLocation& end, unsigned startColumn, unsigned endColumn, SourceElements*, VarStack*, FunctionStack*, IdentifierSet&, const SourceCode&, CodeFeatures, int numConstants);
+        int startStartOffset() const { return m_startStartOffset; }
+        bool isInStrictContext() const { return m_isInStrictContext; }
+        SuperBinding superBinding() { return static_cast<SuperBinding>(m_superBinding); }
+        ConstructorKind constructorKind() { return static_cast<ConstructorKind>(m_constructorKind); }
+        bool isArrowFunctionBodyExpression() const { return m_isArrowFunctionBodyExpression; }
 
+        void setLoc(unsigned firstLine, unsigned lastLine, int startOffset, int lineStartOffset)
+        {
+            m_lastLine = lastLine;
+            m_position = JSTextPosition(firstLine, startOffset, lineStartOffset);
+            ASSERT(m_position.offset >= m_position.lineStartOffset);
+        }
+        unsigned lastLine() const { return m_lastLine; }
+
+    protected:
         Identifier m_ident;
         Identifier m_inferredName;
-        FunctionNameIsInScopeToggle m_functionNameIsInScopeToggle;
-        RefPtr<FunctionParameters> m_parameters;
+        FunctionMode m_functionMode;
+        unsigned m_startColumn;
+        unsigned m_endColumn;
+        int m_functionKeywordStart;
         int m_functionNameStart;
+        int m_parametersStart;
+        SourceCode m_source;
+        int m_startStartOffset;
+        unsigned m_parameterCount;
+        int m_lastLine;
+        SourceParseMode m_parseMode;
+        unsigned m_isInStrictContext : 1;
+        unsigned m_superBinding : 1;
+        unsigned m_constructorKind : 2;
+        unsigned m_isArrowFunctionBodyExpression : 1;
+    };
+
+    class FunctionNode final : public ScopeNode {
+    public:
+        FunctionNode(ParserArena&, const JSTokenLocation& start, const JSTokenLocation& end, unsigned startColumn, unsigned endColumn, SourceElements*, VariableEnvironment&, FunctionStack&, VariableEnvironment&, FunctionParameters*, const SourceCode&, CodeFeatures, int numConstants);
+
+        FunctionParameters* parameters() const { return m_parameters; }
+
+        virtual void emitBytecode(BytecodeGenerator&, RegisterID* = 0) override;
+
+        void finishParsing(const Identifier&, FunctionMode);
+        
+        const Identifier& ident() { return m_ident; }
+
+        FunctionMode functionMode() { return m_functionMode; }
+
+        unsigned startColumn() const { return m_startColumn; }
+        unsigned endColumn() const { return m_endColumn; }
+
+        static const bool scopeIsFunction = true;
+
+    private:
+        Identifier m_ident;
+        FunctionMode m_functionMode;
+        FunctionParameters* m_parameters;
         unsigned m_startColumn;
         unsigned m_endColumn;
     };
 
-    class FuncExprNode : public ExpressionNode {
+    class BaseFuncExprNode : public ExpressionNode {
     public:
-        FuncExprNode(const JSTokenLocation&, const Identifier&, FunctionBodyNode*, const SourceCode&, ParameterNode* = 0);
+        BaseFuncExprNode(const JSTokenLocation&, const Identifier&, FunctionMetadataNode*, const SourceCode&);
+
+        FunctionMetadataNode* metadata() { return m_metadata; }
+
+    protected:
+        FunctionMetadataNode* m_metadata;
+    };
+
 
-        FunctionBodyNode* body() { return m_body; }
+    class FuncExprNode : public BaseFuncExprNode {
+    public:
+        FuncExprNode(const JSTokenLocation&, const Identifier&, FunctionMetadataNode*, const SourceCode&);
 
     private:
         virtual RegisterID* emitBytecode(BytecodeGenerator&, RegisterID* = 0) override;
 
         virtual bool isFuncExprNode() const override { return true; }
+    };
+
+    class ArrowFuncExprNode : public BaseFuncExprNode {
+    public:
+        ArrowFuncExprNode(const JSTokenLocation&, const Identifier&, FunctionMetadataNode*, const SourceCode&);
 
-        FunctionBodyNode* m_body;
+    private:
+        virtual RegisterID* emitBytecode(BytecodeGenerator&, RegisterID* = 0) override;
+
+        virtual bool isArrowFuncExprNode() const override { return true; }
     };
 
-    class DeconstructionPatternNode : public RefCounted<DeconstructionPatternNode> {
-        WTF_MAKE_NONCOPYABLE(DeconstructionPatternNode);
-        WTF_MAKE_FAST_ALLOCATED;
+    class YieldExprNode final : public ExpressionNode, public ThrowableExpressionData {
+    public:
+        YieldExprNode(const JSTokenLocation&, ExpressionNode* argument, bool delegate);
+
+        ExpressionNode* argument() const { return m_argument; }
+        bool delegate() const { return m_delegate; }
 
+    private:
+        virtual RegisterID* emitBytecode(BytecodeGenerator&, RegisterID* = 0) override;
+
+        ExpressionNode* m_argument;
+        bool m_delegate;
+    };
+
+    class ClassExprNode final : public ExpressionNode, public VariableEnvironmentNode {
     public:
+        using ParserArenaDeletable::operator new;
+
+        ClassExprNode(const JSTokenLocation&, const Identifier&, VariableEnvironment& classEnvironment, ExpressionNode* constructorExpresssion,
+            ExpressionNode* parentClass, PropertyListNode* instanceMethods, PropertyListNode* staticMethods);
+
+        const Identifier& name() { return m_name; }
+
+    private:
+        virtual RegisterID* emitBytecode(BytecodeGenerator&, RegisterID* = 0) override;
+
+        const Identifier& m_name;
+        ExpressionNode* m_constructorExpression;
+        ExpressionNode* m_classHeritage;
+        PropertyListNode* m_instanceMethods;
+        PropertyListNode* m_staticMethods;
+    };
+
+    class DestructuringPatternNode : public ParserArenaFreeable {
+    public:
+        virtual ~DestructuringPatternNode() { }
         virtual void collectBoundIdentifiers(Vector<Identifier>&) const = 0;
         virtual void bindValue(BytecodeGenerator&, RegisterID* source) const = 0;
         virtual void toString(StringBuilder&) const = 0;
 
         virtual bool isBindingNode() const { return false; }
+        virtual bool isRestParameter() const { return false; }
         virtual RegisterID* emitDirectBinding(BytecodeGenerator&, RegisterID*, ExpressionNode*) { return 0; }
         
-        virtual ~DeconstructionPatternNode() = 0;
-        
     protected:
-        DeconstructionPatternNode(VM*);
+        DestructuringPatternNode();
     };
 
-    class ArrayPatternNode : public DeconstructionPatternNode {
+    class ArrayPatternNode : public DestructuringPatternNode, public ThrowableExpressionData, public ParserArenaDeletable {
     public:
-        static PassRefPtr<ArrayPatternNode> create(VM*);
-        void appendIndex(const JSTokenLocation&, DeconstructionPatternNode* node)
+        using ParserArenaDeletable::operator new;
+
+        ArrayPatternNode();
+        enum class BindingType {
+            Elision,
+            Element,
+            RestElement
+        };
+
+        void appendIndex(BindingType bindingType, const JSTokenLocation&, DestructuringPatternNode* node, ExpressionNode* defaultValue)
         {
-            m_targetPatterns.append(node);
+            m_targetPatterns.append({ bindingType, node, defaultValue });
         }
 
     private:
-        ArrayPatternNode(VM*);
+        struct Entry {
+            BindingType bindingType;
+            DestructuringPatternNode* pattern;
+            ExpressionNode* defaultValue;
+        };
         virtual void collectBoundIdentifiers(Vector<Identifier>&) const override;
         virtual void bindValue(BytecodeGenerator&, RegisterID*) const override;
         virtual RegisterID* emitDirectBinding(BytecodeGenerator&, RegisterID* dst, ExpressionNode*) override;
         virtual void toString(StringBuilder&) const override;
 
-        Vector<RefPtr<DeconstructionPatternNode>> m_targetPatterns;
+        Vector<Entry> m_targetPatterns;
     };
     
-    class ObjectPatternNode : public DeconstructionPatternNode {
+    class ObjectPatternNode : public DestructuringPatternNode, public ParserArenaDeletable {
     public:
-        static PassRefPtr<ObjectPatternNode> create(VM*);
-        void appendEntry(const JSTokenLocation&, const Identifier& identifier, bool wasString, DeconstructionPatternNode* pattern)
+        using ParserArenaDeletable::operator new;
+        
+        ObjectPatternNode();
+        void appendEntry(const JSTokenLocation&, const Identifier& identifier, bool wasString, DestructuringPatternNode* pattern, ExpressionNode* defaultValue)
         {
-            m_targetPatterns.append(Entry(identifier, wasString, pattern));
+            m_targetPatterns.append(Entry{ identifier, nullptr, wasString, pattern, defaultValue });
         }
-        
+
+        void appendEntry(const JSTokenLocation&, ExpressionNode* propertyExpression, DestructuringPatternNode* pattern, ExpressionNode* defaultValue)
+        {
+            m_targetPatterns.append(Entry{ Identifier(), propertyExpression, false, pattern, defaultValue });
+        }
+
     private:
-        ObjectPatternNode(VM*);
         virtual void collectBoundIdentifiers(Vector<Identifier>&) const override;
         virtual void bindValue(BytecodeGenerator&, RegisterID*) const override;
         virtual void toString(StringBuilder&) const override;
         struct Entry {
-            Entry(const Identifier& propertyName, bool wasString, DeconstructionPatternNode* pattern)
-                : propertyName(propertyName)
-                , wasString(wasString)
-                , pattern(pattern)
-            {
-            }
-            Identifier propertyName;
+            const Identifier& propertyName;
+            ExpressionNode* propertyExpression;
             bool wasString;
-            RefPtr<DeconstructionPatternNode> pattern;
+            DestructuringPatternNode* pattern;
+            ExpressionNode* defaultValue;
         };
         Vector<Entry> m_targetPatterns;
     };
 
-    class BindingNode : public DeconstructionPatternNode {
+    class BindingNode : public DestructuringPatternNode {
     public:
-        static PassRefPtr<BindingNode> create(VM*, const Identifier& boundProperty, const JSTextPosition& start, const JSTextPosition& end);
+        BindingNode(const Identifier& boundProperty, const JSTextPosition& start, const JSTextPosition& end, AssignmentContext);
         const Identifier& boundProperty() const { return m_boundProperty; }
 
         const JSTextPosition& divotStart() const { return m_divotStart; }
         const JSTextPosition& divotEnd() const { return m_divotEnd; }
         
     private:
-        BindingNode(VM*, const Identifier& boundProperty, const JSTextPosition& start, const JSTextPosition& end);
-
         virtual void collectBoundIdentifiers(Vector<Identifier>&) const override;
         virtual void bindValue(BytecodeGenerator&, RegisterID*) const override;
         virtual void toString(StringBuilder&) const override;
@@ -1660,35 +2063,84 @@ namespace JSC {
 
         JSTextPosition m_divotStart;
         JSTextPosition m_divotEnd;
-        Identifier m_boundProperty;
+        const Identifier& m_boundProperty;
+        AssignmentContext m_bindingContext;
     };
 
-    class DeconstructingAssignmentNode : public ExpressionNode, public ParserArenaDeletable {
+    class RestParameterNode : public DestructuringPatternNode {
     public:
-        DeconstructingAssignmentNode(const JSTokenLocation&, PassRefPtr<DeconstructionPatternNode>, ExpressionNode*);
-        DeconstructionPatternNode* bindings() { return m_bindings.get(); }
-        
-        using ParserArenaDeletable::operator new;
+        RestParameterNode(const Identifier& boundProperty, unsigned numParametersToSkip, const JSTextPosition& start, const JSTextPosition& end);
+
+        bool isRestParameter() const override { return true; }
+
+        void emit(BytecodeGenerator&);
+
+        const Identifier& name() const { return m_name; }
 
     private:
-        virtual bool isLocation() const override { return true; }
-        virtual bool isDeconstructionNode() const override { return true; }
+        virtual void collectBoundIdentifiers(Vector<Identifier>&) const override;
+        virtual void bindValue(BytecodeGenerator&, RegisterID*) const override;
+        virtual void toString(StringBuilder&) const override;
+
+        const Identifier& m_name;
+        unsigned m_numParametersToSkip;
+        JSTextPosition m_divotStart; // "f" in "...foo"
+        JSTextPosition m_divotEnd;
+    };
+
+    class AssignmentElementNode : public DestructuringPatternNode {
+    public:
+        AssignmentElementNode(ExpressionNode* assignmentTarget, const JSTextPosition& start, const JSTextPosition& end);
+        const ExpressionNode* assignmentTarget() { return m_assignmentTarget; }
+
+        const JSTextPosition& divotStart() const { return m_divotStart; }
+        const JSTextPosition& divotEnd() const { return m_divotEnd; }
+
+    private:
+        virtual void collectBoundIdentifiers(Vector<Identifier>&) const override;
+        virtual void bindValue(BytecodeGenerator&, RegisterID*) const override;
+        virtual void toString(StringBuilder&) const override;
+
+        JSTextPosition m_divotStart;
+        JSTextPosition m_divotEnd;
+        ExpressionNode* m_assignmentTarget;
+    };
+
+    class DestructuringAssignmentNode : public ExpressionNode {
+    public:
+        DestructuringAssignmentNode(const JSTokenLocation&, DestructuringPatternNode*, ExpressionNode*);
+        DestructuringPatternNode* bindings() { return m_bindings; }
+        
+    private:
+        virtual bool isAssignmentLocation() const override { return true; }
+        virtual bool isDestructuringNode() const override { return true; }
         virtual RegisterID* emitBytecode(BytecodeGenerator&, RegisterID* = 0) override;
 
-        RefPtr<DeconstructionPatternNode> m_bindings;
+        DestructuringPatternNode* m_bindings;
         ExpressionNode* m_initializer;
     };
 
     class FuncDeclNode : public StatementNode {
     public:
-        FuncDeclNode(const JSTokenLocation&, const Identifier&, FunctionBodyNode*, const SourceCode&, ParameterNode* = 0);
+        FuncDeclNode(const JSTokenLocation&, const Identifier&, FunctionMetadataNode*, const SourceCode&);
 
-        FunctionBodyNode* body() { return m_body; }
+        virtual bool isFuncDeclNode() const override { return true; }
+        FunctionMetadataNode* metadata() { return m_metadata; }
 
     private:
         virtual void emitBytecode(BytecodeGenerator&, RegisterID* = 0) override;
 
-        FunctionBodyNode* m_body;
+        FunctionMetadataNode* m_metadata;
+    };
+
+    class ClassDeclNode final : public StatementNode {
+    public:
+        ClassDeclNode(const JSTokenLocation&, ExpressionNode* classExpression);
+
+    private:
+        virtual void emitBytecode(BytecodeGenerator&, RegisterID* = 0) override;
+
+        ExpressionNode* m_classDeclaration;
     };
 
     class CaseClauseNode : public ParserArenaFreeable {
@@ -1698,10 +2150,12 @@ namespace JSC {
         ExpressionNode* expr() const { return m_expr; }
 
         void emitBytecode(BytecodeGenerator&, RegisterID* destination);
+        void setStartOffset(int offset) { m_startOffset = offset; }
 
     private:
         ExpressionNode* m_expr;
         SourceElements* m_statements;
+        int m_startOffset;
     };
 
     class ClauseListNode : public ParserArenaFreeable {
@@ -1731,9 +2185,11 @@ namespace JSC {
         ClauseListNode* m_list2;
     };
 
-    class SwitchNode : public StatementNode {
+    class SwitchNode : public StatementNode, public VariableEnvironmentNode {
     public:
-        SwitchNode(const JSTokenLocation&, ExpressionNode*, CaseBlockNode*);
+        using ParserArenaDeletable::operator new;
+
+        SwitchNode(const JSTokenLocation&, ExpressionNode*, CaseBlockNode*, VariableEnvironment&);
 
     private:
         virtual void emitBytecode(BytecodeGenerator&, RegisterID* = 0) override;
@@ -1757,16 +2213,6 @@ namespace JSC {
         ArgumentListNode* tail;
     };
 
-    struct ConstDeclList {
-        ConstDeclNode* head;
-        ConstDeclNode* tail;
-    };
-
-    struct ParameterList {
-        ParameterNode* head;
-        ParameterNode* tail;
-    };
-
     struct ClauseList {
         ClauseListNode* head;
         ClauseListNode* tail;