Introduce with scope and rework variable resolution.

Review URL: http://codereview.chromium.org/7904008

git-svn-id: http://v8.googlecode.com/svn/branches/bleeding_edge@9650 ce2b1a6d-e550-0410-aec6-3dcde31c8c00

src/arm/full-codegen-arm.cc

@@ -1141,7 +1141,7 @@ void FullCodeGenerator::EmitLoadGlobalCheckExtensions(Variable* var,
     }
     // If no outer scope calls eval, we do not need to check more
     // context extensions.
-    if (!s->outer_scope_calls_eval() || s->is_eval_scope()) break;
+    if (!s->outer_scope_calls_non_strict_eval() || s->is_eval_scope()) break;
     s = s->outer_scope();
   }
 

src/ast.cc

@@ -66,7 +66,6 @@ VariableProxy::VariableProxy(Isolate* isolate, Variable* var)
       name_(var->name()),
       var_(NULL),  // Will be set by the call to BindTo.
       is_this_(var->is_this()),
-      inside_with_(false),
       is_trivial_(false),
       position_(RelocInfo::kNoPosition) {
   BindTo(var);
@@ -76,13 +75,11 @@ VariableProxy::VariableProxy(Isolate* isolate, Variable* var)
 VariableProxy::VariableProxy(Isolate* isolate,
                              Handle<String> name,
                              bool is_this,
-                             bool inside_with,
                              int position)
     : Expression(isolate),
       name_(name),
       var_(NULL),
       is_this_(is_this),
-      inside_with_(inside_with),
       is_trivial_(false),
       position_(position) {
   // Names must be canonicalized for fast equality checks.

src/ast.h

@@ -1128,7 +1128,6 @@ class VariableProxy: public Expression {
   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_; }
   int position() const { return position_; }
 
   void MarkAsTrivial() { is_trivial_ = true; }
@@ -1140,14 +1139,12 @@ class VariableProxy: public Expression {
   Handle<String> name_;
   Variable* var_;  // resolved variable, or NULL
   bool is_this_;
-  bool inside_with_;
   bool is_trivial_;
   int position_;
 
   VariableProxy(Isolate* isolate,
                 Handle<String> name,
                 bool is_this,
-                bool inside_with,
                 int position = RelocInfo::kNoPosition);
 
   friend class Scope;

src/contexts.cc

@@ -266,8 +266,7 @@ bool Context::GlobalIfNotShadowedByEval(Handle<String> name) {
 }
 
 
-void Context::ComputeEvalScopeInfo(bool* outer_scope_calls_eval,
-                                   bool* outer_scope_calls_non_strict_eval) {
+void Context::ComputeEvalScopeInfo(bool* outer_scope_calls_non_strict_eval) {
   // Skip up the context chain checking all the function contexts to see
   // whether they call eval.
   Context* context = this;
@@ -275,14 +274,11 @@ void Context::ComputeEvalScopeInfo(bool* outer_scope_calls_eval,
     if (context->IsFunctionContext()) {
       Handle<SerializedScopeInfo> scope_info(
           context->closure()->shared()->scope_info());
-      if (scope_info->CallsEval()) {
-        *outer_scope_calls_eval = true;
-        if (!scope_info->IsStrictMode()) {
-          // No need to go further since the answers will not change from
-          // here.
-          *outer_scope_calls_non_strict_eval = true;
-          return;
-        }
+      if (scope_info->CallsEval() && !scope_info->IsStrictMode()) {
+        // No need to go further since the answers will not change from
+        // here.
+        *outer_scope_calls_non_strict_eval = true;
+        return;
       }
     }
     context = context->previous();

src/contexts.h

@@ -385,8 +385,7 @@ class Context: public FixedArray {
 
   // Determine if any function scope in the context call eval and if
   // any of those calls are in non-strict mode.
-  void ComputeEvalScopeInfo(bool* outer_scope_calls_eval,
-                            bool* outer_scope_calls_non_strict_eval);
+  void ComputeEvalScopeInfo(bool* outer_scope_calls_non_strict_eval);
 
   // Code generation support.
   static int SlotOffset(int index) {

src/ia32/full-codegen-ia32.cc

@@ -1123,7 +1123,7 @@ void FullCodeGenerator::EmitLoadGlobalCheckExtensions(Variable* var,
     // If no outer scope calls eval, we do not need to check more
     // context extensions.  If we have reached an eval scope, we check
     // all extensions from this point.
-    if (!s->outer_scope_calls_eval() || s->is_eval_scope()) break;
+    if (!s->outer_scope_calls_non_strict_eval() || s->is_eval_scope()) break;
     s = s->outer_scope();
   }
 

src/mips/full-codegen-mips.cc

@@ -1149,7 +1149,7 @@ void FullCodeGenerator::EmitLoadGlobalCheckExtensions(Variable* var,
     }
     // If no outer scope calls eval, we do not need to check more
     // context extensions.
-    if (!s->outer_scope_calls_eval() || s->is_eval_scope()) break;
+    if (!s->outer_scope_calls_non_strict_eval() || s->is_eval_scope()) break;
     s = s->outer_scope();
   }
 

src/parser.cc

@@ -407,9 +407,9 @@ unsigned* ScriptDataImpl::ReadAddress(int position) {
 }
 
 
-Scope* Parser::NewScope(Scope* parent, Scope::Type type, bool inside_with) {
+Scope* Parser::NewScope(Scope* parent, Scope::Type type) {
   Scope* result = new(zone()) Scope(parent, type);
-  result->Initialize(inside_with);
+  result->Initialize();
   return result;
 }
 
@@ -459,13 +459,31 @@ class TargetScope BASE_EMBEDDED {
 
 
 // ----------------------------------------------------------------------------
-// LexicalScope is a support class to facilitate manipulation of the
-// Parser's scope stack. The constructor sets the parser's top scope
-// to the incoming scope, and the destructor resets it.
-//
-// Additionally, it stores transient information used during parsing.
-// These scopes are not kept around after parsing or referenced by syntax
-// trees so they can be stack-allocated and hence used by the pre-parser.
+// LexicalScope and SaveScope are stack allocated support classes to facilitate
+// anipulation of the Parser's scope stack. The constructor sets the parser's
+// top scope to the incoming scope, and the destructor resets it. Additionally,
+// LexicalScope stores transient information used during parsing.
+
+
+class SaveScope BASE_EMBEDDED {
+ public:
+  SaveScope(Parser* parser, Scope* scope)
+      : parser_(parser),
+        previous_top_scope_(parser->top_scope_) {
+    parser->top_scope_ = scope;
+  }
+
+  ~SaveScope() {
+    parser_->top_scope_ = previous_top_scope_;
+  }
+
+ private:
+  // Bookkeeping
+  Parser* parser_;
+  // Previous values
+  Scope* previous_top_scope_;
+};
+
 
 class LexicalScope BASE_EMBEDDED {
  public:
@@ -516,7 +534,6 @@ class LexicalScope BASE_EMBEDDED {
   // Previous values
   LexicalScope* lexical_scope_parent_;
   Scope* previous_scope_;
-  int previous_with_nesting_level_;
   unsigned previous_ast_node_id_;
 };
 
@@ -529,11 +546,9 @@ LexicalScope::LexicalScope(Parser* parser, Scope* scope, Isolate* isolate)
     parser_(parser),
     lexical_scope_parent_(parser->lexical_scope_),
     previous_scope_(parser->top_scope_),
-    previous_with_nesting_level_(parser->with_nesting_level_),
     previous_ast_node_id_(isolate->ast_node_id()) {
   parser->top_scope_ = scope;
   parser->lexical_scope_ = this;
-  parser->with_nesting_level_ = 0;
   isolate->set_ast_node_id(AstNode::kDeclarationsId + 1);
 }
 
@@ -541,7 +556,6 @@ LexicalScope::LexicalScope(Parser* parser, Scope* scope, Isolate* isolate)
 LexicalScope::~LexicalScope() {
   parser_->top_scope_ = previous_scope_;
   parser_->lexical_scope_ = lexical_scope_parent_;
-  parser_->with_nesting_level_ = previous_with_nesting_level_;
   parser_->isolate()->set_ast_node_id(previous_ast_node_id_);
 }
 
@@ -578,7 +592,6 @@ Parser::Parser(Handle<Script> script,
       script_(script),
       scanner_(isolate_->unicode_cache()),
       top_scope_(NULL),
-      with_nesting_level_(0),
       lexical_scope_(NULL),
       target_stack_(NULL),
       allow_natives_syntax_(allow_natives_syntax),
@@ -637,7 +650,7 @@ FunctionLiteral* Parser::DoParseProgram(Handle<String> source,
   Handle<String> no_name = isolate()->factory()->empty_symbol();
 
   FunctionLiteral* result = NULL;
-  { Scope* scope = NewScope(top_scope_, type, inside_with());
+  { Scope* scope = NewScope(top_scope_, type);
     LexicalScope lexical_scope(this, scope, isolate());
     if (strict_mode == kStrictMode) {
       top_scope_->EnableStrictMode();
@@ -727,7 +740,7 @@ FunctionLiteral* Parser::ParseLazy(CompilationInfo* info,
 
   {
     // Parse the function literal.
-    Scope* scope = NewScope(top_scope_, Scope::GLOBAL_SCOPE, inside_with());
+    Scope* scope = NewScope(top_scope_, Scope::GLOBAL_SCOPE);
     if (!info->closure().is_null()) {
       scope = Scope::DeserializeScopeChain(info, scope);
     }
@@ -1429,7 +1442,7 @@ VariableProxy* Parser::Declare(Handle<String> name,
   // a performance issue since it may lead to repeated
   // Runtime::DeclareContextSlot() calls.
   VariableProxy* proxy = declaration_scope->NewUnresolved(
-      name, false, scanner().location().beg_pos);
+      name, scanner().location().beg_pos);
   declaration_scope->AddDeclaration(
       new(zone()) Declaration(proxy, mode, fun, top_scope_));
 
@@ -1582,20 +1595,16 @@ Block* Parser::ParseScopedBlock(ZoneStringList* labels, bool* ok) {
 
   // Construct block expecting 16 statements.
   Block* body = new(zone()) Block(isolate(), labels, 16, false);
-  Scope* saved_scope = top_scope_;
-  Scope* block_scope = NewScope(top_scope_,
-                                Scope::BLOCK_SCOPE,
-                                inside_with());
+  Scope* block_scope = NewScope(top_scope_, Scope::BLOCK_SCOPE);
   if (top_scope_->is_strict_mode()) {
     block_scope->EnableStrictMode();
   }
-  top_scope_ = block_scope;
 
   // Parse the statements and collect escaping labels.
-  TargetCollector collector;
-  Target target(&this->target_stack_, &collector);
   Expect(Token::LBRACE, CHECK_OK);
-  {
+  { SaveScope save_scope(this, block_scope);
+    TargetCollector collector;
+    Target target(&this->target_stack_, &collector);
     Target target_body(&this->target_stack_, body);
     InitializationBlockFinder block_finder(top_scope_, target_stack_);
 
@@ -1608,7 +1617,6 @@ Block* Parser::ParseScopedBlock(ZoneStringList* labels, bool* ok) {
     }
   }
   Expect(Token::RBRACE, CHECK_OK);
-  top_scope_ = saved_scope;
 
   block_scope = block_scope->FinalizeBlockScope();
   body->set_block_scope(block_scope);
@@ -1875,14 +1883,10 @@ Block* Parser::ParseVariableDeclarations(VariableDeclarationContext var_context,
     // as the declaration. Thus dynamic lookups are unnecessary even if the
     // block scope is inside a with.
     if (value != NULL) {
-      bool in_with = (mode == VAR) ? inside_with() : false;
-      VariableProxy* proxy =
-          initialization_scope->NewUnresolved(name, in_with);
+      VariableProxy* proxy = initialization_scope->NewUnresolved(name);
       Assignment* assignment =
           new(zone()) Assignment(isolate(), init_op, proxy, value, position);
-      if (block) {
-        block->AddStatement(new(zone()) ExpressionStatement(assignment));
-      }
+      block->AddStatement(new(zone()) ExpressionStatement(assignment));
     }
 
     if (fni_ != NULL) fni_->Leave();
@@ -2105,10 +2109,12 @@ Statement* Parser::ParseWithStatement(ZoneStringList* labels, bool* ok) {
   Expression* expr = ParseExpression(true, CHECK_OK);
   Expect(Token::RPAREN, CHECK_OK);
 
-  ++with_nesting_level_;
   top_scope_->DeclarationScope()->RecordWithStatement();
-  Statement* stmt = ParseStatement(labels, CHECK_OK);
-  --with_nesting_level_;
+  Scope* with_scope = NewScope(top_scope_, Scope::WITH_SCOPE);
+  Statement* stmt;
+  { SaveScope save_scope(this, with_scope);
+    stmt = ParseStatement(labels, CHECK_OK);
+  }
   return new(zone()) WithStatement(expr, stmt);
 }
 
@@ -2245,17 +2251,15 @@ TryStatement* Parser::ParseTryStatement(bool* ok) {
 
     if (peek() == Token::LBRACE) {
       Target target(&this->target_stack_, &catch_collector);
-      catch_scope = NewScope(top_scope_, Scope::CATCH_SCOPE, inside_with());
+      catch_scope = NewScope(top_scope_, Scope::CATCH_SCOPE);
       if (top_scope_->is_strict_mode()) {
         catch_scope->EnableStrictMode();
       }
       VariableMode mode = harmony_scoping_ ? LET : VAR;
       catch_variable = catch_scope->DeclareLocal(name, mode);
 
-      Scope* saved_scope = top_scope_;
-      top_scope_ = catch_scope;
+      SaveScope save_scope(this, catch_scope);
       catch_block = ParseBlock(NULL, CHECK_OK);
-      top_scope_ = saved_scope;
     } else {
       Expect(Token::LBRACE, CHECK_OK);
     }
@@ -2374,7 +2378,7 @@ Statement* Parser::ParseForStatement(ZoneStringList* labels, bool* ok) {
           ParseVariableDeclarations(kForStatement, &name, CHECK_OK);
 
       if (peek() == Token::IN && !name.is_null()) {
-        VariableProxy* each = top_scope_->NewUnresolved(name, inside_with());
+        VariableProxy* each = top_scope_->NewUnresolved(name);
         ForInStatement* loop = new(zone()) ForInStatement(isolate(), labels);
         Target target(&this->target_stack_, loop);
 
@@ -3065,9 +3069,7 @@ Expression* Parser::ParsePrimaryExpression(bool* ok) {
     case Token::FUTURE_STRICT_RESERVED_WORD: {
       Handle<String> name = ParseIdentifier(CHECK_OK);
       if (fni_ != NULL) fni_->PushVariableName(name);
-      result = top_scope_->NewUnresolved(name,
-                                         inside_with(),
-                                         scanner().location().beg_pos);
+      result = top_scope_->NewUnresolved(name, scanner().location().beg_pos);
       break;
     }
 
@@ -3714,9 +3716,10 @@ FunctionLiteral* Parser::ParseFunctionLiteral(Handle<String> function_name,
   // Function declarations are function scoped in normal mode, so they are
   // hoisted. In harmony block scoping mode they are block scoped, so they
   // are not hoisted.
-  Scope* scope = (type == FunctionLiteral::DECLARATION && !harmony_scoping_)
-      ? NewScope(top_scope_->DeclarationScope(), Scope::FUNCTION_SCOPE, false)
-      : NewScope(top_scope_, Scope::FUNCTION_SCOPE, inside_with());
+  Scope* scope = (type == FunctionLiteral::DECLARATION &&
+                  !harmony_scoping_)
+      ? NewScope(top_scope_->DeclarationScope(), Scope::FUNCTION_SCOPE)
+      : NewScope(top_scope_, Scope::FUNCTION_SCOPE);
   ZoneList<Statement*>* body = new(zone()) ZoneList<Statement*>(8);
   int materialized_literal_count;
   int expected_property_count;
@@ -3779,8 +3782,7 @@ FunctionLiteral* Parser::ParseFunctionLiteral(Handle<String> function_name,
     // instead of Variables and Proxis as is the case now.
     if (type == FunctionLiteral::NAMED_EXPRESSION) {
       Variable* fvar = top_scope_->DeclareFunctionVar(function_name);
-      VariableProxy* fproxy =
-          top_scope_->NewUnresolved(function_name, inside_with());
+      VariableProxy* fproxy = top_scope_->NewUnresolved(function_name);
       fproxy->BindTo(fvar);
       body->Add(new(zone()) ExpressionStatement(
           new(zone()) Assignment(isolate(),

src/parser.h

@@ -43,6 +43,7 @@ class ParserLog;
 class PositionStack;
 class Target;
 class LexicalScope;
+class SaveScope;
 
 template <typename T> class ZoneListWrapper;
 
@@ -473,7 +474,7 @@ class Parser {
   void ReportInvalidPreparseData(Handle<String> name, bool* ok);
   void ReportMessage(const char* message, Vector<const char*> args);
 
-  bool inside_with() const { return with_nesting_level_ > 0; }
+  bool inside_with() const { return top_scope_->inside_with(); }
   JavaScriptScanner& scanner()  { return scanner_; }
   Mode mode() const { return mode_; }
   ScriptDataImpl* pre_data() const { return pre_data_; }
@@ -669,7 +670,7 @@ class Parser {
     return &empty;
   }
 
-  Scope* NewScope(Scope* parent, Scope::Type type, bool inside_with);
+  Scope* NewScope(Scope* parent, Scope::Type type);
 
   Handle<String> LookupSymbol(int symbol_id);
 
@@ -714,7 +715,6 @@ class Parser {
   JavaScriptScanner scanner_;
 
   Scope* top_scope_;
-  int with_nesting_level_;
 
   LexicalScope* lexical_scope_;
   Mode mode_;
@@ -734,6 +734,7 @@ class Parser {
   bool harmony_scoping_;
 
   friend class LexicalScope;
+  friend class SaveScope;
 };
 
 

src/scopes.h

@@ -94,7 +94,8 @@ class Scope: public ZoneObject {
     FUNCTION_SCOPE,  // The top-level scope for a function.
     GLOBAL_SCOPE,    // The top-level scope for a program or a top-level eval.
     CATCH_SCOPE,     // The scope introduced by catch.
-    BLOCK_SCOPE      // The scope introduced by a new block.
+    BLOCK_SCOPE,     // The scope introduced by a new block.
+    WITH_SCOPE       // The scope introduced by with.
   };
 
   Scope(Scope* outer_scope, Type type);
@@ -110,7 +111,7 @@ class Scope: public ZoneObject {
   // The scope name is only used for printing/debugging.
   void SetScopeName(Handle<String> scope_name) { scope_name_ = scope_name; }
 
-  void Initialize(bool inside_with);
+  void Initialize();
 
   // Checks if the block scope is redundant, i.e. it does not contain any
   // block scoped declarations. In that case it is removed from the scope
@@ -149,7 +150,6 @@ class Scope: public ZoneObject {
 
   // Create a new unresolved variable.
   VariableProxy* NewUnresolved(Handle<String> name,
-                               bool inside_with,
                                int position = RelocInfo::kNoPosition);
 
   // Remove a unresolved variable. During parsing, an unresolved variable
@@ -199,7 +199,7 @@ class Scope: public ZoneObject {
   void RecordWithStatement() { scope_contains_with_ = true; }
 
   // Inform the scope that the corresponding code contains an eval call.
-  void RecordEvalCall() { scope_calls_eval_ = true; }
+  void RecordEvalCall() { if (!is_global_scope()) scope_calls_eval_ = true; }
 
   // Enable strict mode for the scope (unless disabled by a global flag).
   void EnableStrictMode() {
@@ -215,6 +215,10 @@ class Scope: public ZoneObject {
   bool is_global_scope() const { return type_ == GLOBAL_SCOPE; }
   bool is_catch_scope() const { return type_ == CATCH_SCOPE; }
   bool is_block_scope() const { return type_ == BLOCK_SCOPE; }
+  bool is_with_scope() const { return type_ == WITH_SCOPE; }
+  bool is_declaration_scope() const {
+    return is_eval_scope() || is_function_scope() || is_global_scope();
+  }
   bool is_strict_mode() const { return strict_mode_; }
   bool is_strict_mode_eval_scope() const {
     return is_eval_scope() && is_strict_mode();
@@ -222,7 +226,9 @@ class Scope: public ZoneObject {
 
   // Information about which scopes calls eval.
   bool calls_eval() const { return scope_calls_eval_; }
-  bool outer_scope_calls_eval() const { return outer_scope_calls_eval_; }
+  bool calls_non_strict_eval() {
+    return scope_calls_eval_ && !is_strict_mode();
+  }
   bool outer_scope_calls_non_strict_eval() const {
     return outer_scope_calls_non_strict_eval_;
   }
@@ -383,10 +389,8 @@ class Scope: public ZoneObject {
   bool strict_mode_;
 
   // Computed via PropagateScopeInfo.
-  bool outer_scope_calls_eval_;
   bool outer_scope_calls_non_strict_eval_;
   bool inner_scope_calls_eval_;
-  bool outer_scope_is_eval_scope_;
   bool force_eager_compilation_;
 
   // True if it doesn't need scope resolution (e.g., if the scope was
@@ -396,7 +400,7 @@ class Scope: public ZoneObject {
   // Computed as variables are declared.
   int num_var_or_const_;
 
-  // Computed via AllocateVariables; function scopes only.
+  // Computed via AllocateVariables; function, block and catch scopes only.
   int num_stack_slots_;
   int num_heap_slots_;
 
@@ -409,9 +413,57 @@ class Scope: public ZoneObject {
   Variable* NonLocal(Handle<String> name, VariableMode mode);
 
   // Variable resolution.
+  // Possible results of a recursive variable lookup telling if and how a
+  // variable is bound. These are returned in the output parameter *binding_kind
+  // of the LookupRecursive function.
+  enum BindingKind {
+    // The variable reference could be statically resolved to a variable binding
+    // which is returned. There is no 'with' statement between the reference and
+    // the binding and no scope between the reference scope (inclusive) and
+    // binding scope (exclusive) makes a non-strict 'eval' call.
+    BOUND,
+
+    // The variable reference could be statically resolved to a variable binding
+    // which is returned. There is no 'with' statement between the reference and
+    // the binding, but some scope between the reference scope (inclusive) and
+    // binding scope (exclusive) makes a non-strict 'eval' call, that might
+    // possibly introduce variable bindings shadowing the found one. Thus the
+    // found variable binding is just a guess.
+    BOUND_EVAL_SHADOWED,
+
+    // The variable reference could not be statically resolved to any binding
+    // and thus should be considered referencing a global variable. NULL is
+    // returned. The variable reference is not inside any 'with' statement and
+    // no scope between the reference scope (inclusive) and global scope
+    // (exclusive) makes a non-strict 'eval' call.
+    UNBOUND,
+
+    // The variable reference could not be statically resolved to any binding
+    // NULL is returned. The variable reference is not inside any 'with'
+    // statement, but some scope between the reference scope (inclusive) and
+    // global scope (exclusive) makes a non-strict 'eval' call, that might
+    // possibly introduce a variable binding. Thus the reference should be
+    // considered referencing a global variable unless it is shadowed by an
+    // 'eval' introduced binding.
+    UNBOUND_EVAL_SHADOWED,
+
+    // The variable could not be statically resolved and needs to be looked up
+    // dynamically. NULL is returned. There are two possible reasons:
+    // * A 'with' statement has been encountered and there is no variable
+    //   binding for the name between the variable reference and the 'with'.
+    //   The variable potentially references a property of the 'with' object.
+    // * The code is being executed as part of a call to 'eval' and the calling
+    //   context chain contains either a variable binding for the name or it
+    //   contains a 'with' context.
+    DYNAMIC_LOOKUP
+  };
+
+  // Lookup a variable reference given by name recursively starting with this
+  // scope. If the code is executed because of a call to 'eval', the context
+  // parameter should be set to the calling context of 'eval'.
   Variable* LookupRecursive(Handle<String> name,
-                            bool from_inner_function,
-                            Variable** invalidated_local);
+                            Handle<Context> context,
+                            BindingKind* binding_kind);
   void ResolveVariable(Scope* global_scope,
                        Handle<Context> context,
                        VariableProxy* proxy);
@@ -419,9 +471,7 @@ class Scope: public ZoneObject {
                                    Handle<Context> context);
 
   // Scope analysis.
-  bool PropagateScopeInfo(bool outer_scope_calls_eval,
-                          bool outer_scope_calls_non_strict_eval,
-                          bool outer_scope_is_eval_scope);
+  bool PropagateScopeInfo(bool outer_scope_calls_non_strict_eval);
   bool HasTrivialContext() const;
 
   // Predicates.
@@ -438,7 +488,7 @@ class Scope: public ZoneObject {
   void AllocateVariablesRecursively();
 
  private:
-  // Construct a function or block scope based on the scope info.
+  // Construct a scope based on the scope info.
   Scope(Scope* inner_scope, Type type, Handle<SerializedScopeInfo> scope_info);
 
   // Construct a catch scope with a binding for the name.

src/variables.h

@@ -154,6 +154,10 @@ class Variable: public ZoneObject {
   Location location_;
   int index_;
 
+  // If this field is set, this variable references the stored locally bound
+  // variable, but it might be shadowed by variable bindings introduced by
+  // non-strict 'eval' calls between the reference scope (inclusive) and the
+  // binding scope (exclusive).
   Variable* local_if_not_shadowed_;
 
   // Valid as a LHS? (const and this are not valid LHS, for example)

src/x64/full-codegen-x64.cc

@@ -1099,7 +1099,7 @@ void FullCodeGenerator::EmitLoadGlobalCheckExtensions(Variable* var,
     // If no outer scope calls eval, we do not need to check more
     // context extensions.  If we have reached an eval scope, we check
     // all extensions from this point.
-    if (!s->outer_scope_calls_eval() || s->is_eval_scope()) break;
+    if (!s->outer_scope_calls_non_strict_eval() || s->is_eval_scope()) break;
     s = s->outer_scope();
   }