Revert "Resolve references to "this" the same way as normal variables"

... and the following two
"PPC: Resolve references to "this" the same way as normal variables"
"Remove Scope::scope_uses_this_ flag"

R=hablich@chromium.org
BUG=chromium:487289
LOG=N

Review URL: https://codereview.chromium.org/1134003003

Cr-Commit-Position: refs/heads/master@{#28395}

src/arm/full-codegen-arm.cc

@@ -127,7 +127,7 @@ void FullCodeGenerator::Generate() {
   // global proxy when called as functions (without an explicit receiver
   // object).
   if (is_sloppy(info->language_mode()) && !info->is_native() &&
-      info->MayUseThis() && info->scope()->has_this_declaration()) {
+      info->MayUseThis()) {
     Label ok;
     int receiver_offset = info->scope()->num_parameters() * kPointerSize;
     __ ldr(r2, MemOperand(sp, receiver_offset));
@@ -216,9 +216,8 @@ void FullCodeGenerator::Generate() {
     __ str(r0, MemOperand(fp, StandardFrameConstants::kContextOffset));
     // Copy any necessary parameters into the context.
     int num_parameters = info->scope()->num_parameters();
-    int first_parameter = info->scope()->has_this_declaration() ? -1 : 0;
+    for (int i = 0; i < num_parameters; i++) {
-    for (int i = first_parameter; i < num_parameters; i++) {
+      Variable* var = scope()->parameter(i);
-      Variable* var = (i == -1) ? scope()->receiver() : scope()->parameter(i);
       if (var->IsContextSlot()) {
         int parameter_offset = StandardFrameConstants::kCallerSPOffset +
             (num_parameters - 1 - i) * kPointerSize;
@@ -3068,9 +3067,8 @@ void FullCodeGenerator::EmitResolvePossiblyDirectEval(int arg_count) {
   __ ldr(r4, MemOperand(fp, JavaScriptFrameConstants::kFunctionOffset));
 
   // r3: the receiver of the enclosing function.
-  Variable* this_var = scope()->LookupThis();
+  int receiver_offset = 2 + info_->scope()->num_parameters();
-  DCHECK_NOT_NULL(this_var);
+  __ ldr(r3, MemOperand(fp, receiver_offset * kPointerSize));
-  __ ldr(r3, VarOperand(this_var, r3));
 
   // r2: language mode.
   __ mov(r2, Operand(Smi::FromInt(language_mode())));

src/arm/lithium-codegen-arm.cc

@@ -121,7 +121,7 @@ bool LCodeGen::GeneratePrologue() {
     // global proxy when called as functions (without an explicit receiver
     // object).
     if (is_sloppy(info_->language_mode()) && info()->MayUseThis() &&
-        !info_->is_native() && info_->scope()->has_this_declaration()) {
+        !info_->is_native()) {
       Label ok;
       int receiver_offset = info_->scope()->num_parameters() * kPointerSize;
       __ ldr(r2, MemOperand(sp, receiver_offset));
@@ -197,9 +197,8 @@ bool LCodeGen::GeneratePrologue() {
     __ str(r0, MemOperand(fp, StandardFrameConstants::kContextOffset));
     // Copy any necessary parameters into the context.
     int num_parameters = scope()->num_parameters();
-    int first_parameter = scope()->has_this_declaration() ? -1 : 0;
+    for (int i = 0; i < num_parameters; i++) {
-    for (int i = first_parameter; i < num_parameters; i++) {
+      Variable* var = scope()->parameter(i);
-      Variable* var = (i == -1) ? scope()->receiver() : scope()->parameter(i);
       if (var->IsContextSlot()) {
         int parameter_offset = StandardFrameConstants::kCallerSPOffset +
             (num_parameters - 1 - i) * kPointerSize;

src/arm64/full-codegen-arm64.cc

@@ -125,7 +125,7 @@ void FullCodeGenerator::Generate() {
   // global proxy when called as functions (without an explicit receiver
   // object).
   if (is_sloppy(info->language_mode()) && !info->is_native() &&
-      info->MayUseThis() && info->scope()->has_this_declaration()) {
+      info->MayUseThis()) {
     Label ok;
     int receiver_offset = info->scope()->num_parameters() * kXRegSize;
     __ Peek(x10, receiver_offset);
@@ -217,9 +217,8 @@ void FullCodeGenerator::Generate() {
     __ Str(x0, MemOperand(fp, StandardFrameConstants::kContextOffset));
     // Copy any necessary parameters into the context.
     int num_parameters = info->scope()->num_parameters();
-    int first_parameter = info->scope()->has_this_declaration() ? -1 : 0;
+    for (int i = 0; i < num_parameters; i++) {
-    for (int i = first_parameter; i < num_parameters; i++) {
+      Variable* var = scope()->parameter(i);
-      Variable* var = (i == -1) ? scope()->receiver() : scope()->parameter(i);
       if (var->IsContextSlot()) {
         int parameter_offset = StandardFrameConstants::kCallerSPOffset +
             (num_parameters - 1 - i) * kPointerSize;
@@ -2753,9 +2752,8 @@ void FullCodeGenerator::EmitResolvePossiblyDirectEval(int arg_count) {
 
   __ Ldr(x10, MemOperand(fp, JavaScriptFrameConstants::kFunctionOffset));
   // Prepare to push the receiver of the enclosing function.
-  Variable* this_var = scope()->LookupThis();
+  int receiver_offset = 2 + info_->scope()->num_parameters();
-  DCHECK_NOT_NULL(this_var);
+  __ Ldr(x11, MemOperand(fp, receiver_offset * kPointerSize));
-  __ Ldr(x11, VarOperand(this_var, x11));
 
   // Prepare to push the language mode.
   __ Mov(x12, Smi::FromInt(language_mode()));

src/arm64/lithium-codegen-arm64.cc

@@ -669,7 +669,7 @@ bool LCodeGen::GeneratePrologue() {
     // global proxy when called as functions (without an explicit receiver
     // object).
     if (is_sloppy(info_->language_mode()) && info()->MayUseThis() &&
-        !info()->is_native() && info()->scope()->has_this_declaration()) {
+        !info_->is_native()) {
       Label ok;
       int receiver_offset = info_->scope()->num_parameters() * kXRegSize;
       __ Peek(x10, receiver_offset);
@@ -728,9 +728,8 @@ bool LCodeGen::GeneratePrologue() {
     __ Str(x0, MemOperand(fp, StandardFrameConstants::kContextOffset));
     // Copy any necessary parameters into the context.
     int num_parameters = scope()->num_parameters();
-    int first_parameter = scope()->has_this_declaration() ? -1 : 0;
+    for (int i = 0; i < num_parameters; i++) {
-    for (int i = first_parameter; i < num_parameters; i++) {
+      Variable* var = scope()->parameter(i);
-      Variable* var = (i == -1) ? scope()->receiver() : scope()->parameter(i);
       if (var->IsContextSlot()) {
         Register value = x0;
         Register scratch = x3;

src/compiler.cc

@@ -223,7 +223,8 @@ bool CompilationInfo::is_simple_parameter_list() {
 
 
 bool CompilationInfo::MayUseThis() const {
-  return scope()->has_this_declaration() && scope()->receiver()->is_used();
+  return scope()->uses_this() || scope()->inner_uses_this() ||
+         scope()->calls_sloppy_eval();
 }
 
 

src/compiler/ast-graph-builder.cc

@@ -512,21 +512,15 @@ bool AstGraphBuilder::CreateGraph(bool constant_context, bool stack_check) {
 
   // Build receiver check for sloppy mode if necessary.
   // TODO(mstarzinger/verwaest): Should this be moved back into the CallIC?
-  Node* patched_receiver = nullptr;
+  Node* original_receiver = env.Lookup(scope->receiver());
-  if (scope->has_this_declaration()) {
+  Node* patched_receiver = BuildPatchReceiverToGlobalProxy(original_receiver);
-    Node* original_receiver = NewNode(common()->Parameter(0), graph()->start());
+  env.Bind(scope->receiver(), patched_receiver);
-    patched_receiver = BuildPatchReceiverToGlobalProxy(original_receiver);
-    if (scope->receiver()->IsStackAllocated()) {
-      env.Bind(scope->receiver(), patched_receiver);
-    }
-  }
 
   // Build function context only if there are context allocated variables.
   int heap_slots = info()->num_heap_slots() - Context::MIN_CONTEXT_SLOTS;
   if (heap_slots > 0) {
     // Push a new inner context scope for the function.
-    Node* inner_context =
+    Node* inner_context = BuildLocalFunctionContext(function_context_.get());
-        BuildLocalFunctionContext(function_context_.get(), patched_receiver);
     ContextScope top_context(this, scope, inner_context);
     CreateGraphBody(stack_check);
   } else {
@@ -2256,23 +2250,7 @@ void AstGraphBuilder::VisitCall(Call* expr) {
     // Create node to ask for help resolving potential eval call. This will
     // provide a fully resolved callee and the corresponding receiver.
     Node* function = GetFunctionClosure();
-    // TODO(wingo): ResolvePossibleDirectEval doesn't really need a receiver,
+    Node* receiver = environment()->Lookup(info()->scope()->receiver());
-    // now that eval scopes don't have "this" declarations.  Remove this hack
-    // once ResolvePossibleDirectEval changes.
-    Node* receiver;
-    {
-      Variable* variable = info()->scope()->LookupThis();
-      if (variable->IsStackAllocated()) {
-        receiver = environment()->Lookup(variable);
-      } else {
-        DCHECK(variable->IsContextSlot());
-        int depth = current_scope()->ContextChainLength(variable->scope());
-        bool immutable = variable->maybe_assigned() == kNotAssigned;
-        const Operator* op =
-            javascript()->LoadContext(depth, variable->index(), immutable);
-        receiver = NewNode(op, current_context());
-      }
-    }
     Node* language = jsgraph()->Constant(language_mode());
     Node* position = jsgraph()->Constant(info()->scope()->start_position());
     const Operator* op =
@@ -2752,7 +2730,9 @@ Node* AstGraphBuilder::BuildPatchReceiverToGlobalProxy(Node* receiver) {
   // object). Otherwise there is nothing left to do here.
   if (is_strict(language_mode()) || info()->is_native()) return receiver;
 
-  // There is no need to perform patching if the receiver will never be used.
+  // There is no need to perform patching if the receiver is never used. Note
+  // that scope predicates are purely syntactical, a call to eval might still
+  // inspect the receiver value.
   if (!info()->MayUseThis()) return receiver;
 
   IfBuilder receiver_check(this);
@@ -2769,36 +2749,25 @@ Node* AstGraphBuilder::BuildPatchReceiverToGlobalProxy(Node* receiver) {
 }
 
 
-Node* AstGraphBuilder::BuildLocalFunctionContext(Node* context,
+Node* AstGraphBuilder::BuildLocalFunctionContext(Node* context) {
-                                                 Node* patched_receiver) {
-  Scope* scope = info()->scope();
   Node* closure = GetFunctionClosure();
 
   // Allocate a new local context.
   Node* local_context =
-      scope->is_script_scope()
+      info()->scope()->is_script_scope()
-          ? BuildLocalScriptContext(scope)
+          ? BuildLocalScriptContext(info()->scope())
           : NewNode(javascript()->CreateFunctionContext(), closure);
 
-  if (scope->has_this_declaration() && scope->receiver()->IsContextSlot()) {
-    DCHECK_NOT_NULL(patched_receiver);
-    // Context variable (at bottom of the context chain).
-    Variable* variable = scope->receiver();
-    DCHECK_EQ(0, scope->ContextChainLength(variable->scope()));
-    const Operator* op = javascript()->StoreContext(0, variable->index());
-    NewNode(op, local_context, patched_receiver);
-  }
-
   // Copy parameters into context if necessary.
-  int num_parameters = scope->num_parameters();
+  int num_parameters = info()->scope()->num_parameters();
   for (int i = 0; i < num_parameters; i++) {
-    Variable* variable = scope->parameter(i);
+    Variable* variable = info()->scope()->parameter(i);
     if (!variable->IsContextSlot()) continue;
     // Temporary parameter node. The parameter indices are shifted by 1
     // (receiver is parameter index -1 but environment index 0).
     Node* parameter = NewNode(common()->Parameter(i + 1), graph()->start());
     // Context variable (at bottom of the context chain).
-    DCHECK_EQ(0, scope->ContextChainLength(variable->scope()));
+    DCHECK_EQ(0, info()->scope()->ContextChainLength(variable->scope()));
     const Operator* op = javascript()->StoreContext(0, variable->index());
     NewNode(op, local_context, parameter);
   }

src/compiler/ast-graph-builder.h

@@ -244,7 +244,7 @@ class AstGraphBuilder : public AstVisitor {
   Node* BuildPatchReceiverToGlobalProxy(Node* receiver);
 
   // Builders to create local function, script and block contexts.
-  Node* BuildLocalFunctionContext(Node* context, Node* patched_receiver);
+  Node* BuildLocalFunctionContext(Node* context);
   Node* BuildLocalScriptContext(Scope* scope);
   Node* BuildLocalBlockContext(Scope* scope);
 

src/contexts.cc

@@ -258,13 +258,8 @@ Handle<Object> Context::Lookup(Handle<String> name,
           object->IsJSContextExtensionObject()) {
         maybe = JSReceiver::GetOwnPropertyAttributes(object, name);
       } else if (context->IsWithContext()) {
-        // A with context will never bind "this".
+        LookupIterator it(object, name);
-        if (name->Equals(*isolate->factory()->this_string())) {
+        maybe = UnscopableLookup(&it);
-          maybe = Just(ABSENT);
-        } else {
-          LookupIterator it(object, name);
-          maybe = UnscopableLookup(&it);
-        }
       } else {
         maybe = JSReceiver::GetPropertyAttributes(object, name);
       }

src/heap/heap.h

@@ -232,7 +232,6 @@ namespace internal {
   V(source_string, "source")                                   \
   V(source_url_string, "source_url")                           \
   V(source_mapping_url_string, "source_mapping_url")           \
-  V(this_string, "this")                                       \
   V(global_string, "global")                                   \
   V(ignore_case_string, "ignoreCase")                          \
   V(multiline_string, "multiline")                             \

src/ia32/full-codegen-ia32.cc

@@ -210,9 +210,8 @@ void FullCodeGenerator::Generate() {
 
     // Copy parameters into context if necessary.
     int num_parameters = info->scope()->num_parameters();
-    int first_parameter = info->scope()->has_this_declaration() ? -1 : 0;
+    for (int i = 0; i < num_parameters; i++) {
-    for (int i = first_parameter; i < num_parameters; i++) {
+      Variable* var = scope()->parameter(i);
-      Variable* var = (i == -1) ? scope()->receiver() : scope()->parameter(i);
       if (var->IsContextSlot()) {
         int parameter_offset = StandardFrameConstants::kCallerSPOffset +
             (num_parameters - 1 - i) * kPointerSize;
@@ -2961,9 +2960,7 @@ void FullCodeGenerator::EmitResolvePossiblyDirectEval(int arg_count) {
   // Push the enclosing function.
   __ push(Operand(ebp, JavaScriptFrameConstants::kFunctionOffset));
   // Push the receiver of the enclosing function.
-  Variable* this_var = scope()->LookupThis();
+  __ push(Operand(ebp, (2 + info_->scope()->num_parameters()) * kPointerSize));
-  DCHECK_NOT_NULL(this_var);
-  __ push(VarOperand(this_var, ecx));
   // Push the language mode.
   __ push(Immediate(Smi::FromInt(language_mode())));
 

src/ia32/lithium-codegen-ia32.cc

@@ -141,8 +141,8 @@ bool LCodeGen::GeneratePrologue() {
     // Sloppy mode functions and builtins need to replace the receiver with the
     // global proxy when called as functions (without an explicit receiver
     // object).
-    if (is_sloppy(info()->language_mode()) && info()->MayUseThis() &&
+    if (is_sloppy(info_->language_mode()) && info()->MayUseThis() &&
-        !info()->is_native() && info()->scope()->has_this_declaration()) {
+        !info_->is_native()) {
       Label ok;
       // +1 for return address.
       int receiver_offset = (scope()->num_parameters() + 1) * kPointerSize;
@@ -275,9 +275,8 @@ bool LCodeGen::GeneratePrologue() {
 
     // Copy parameters into context if necessary.
     int num_parameters = scope()->num_parameters();
-    int first_parameter = scope()->has_this_declaration() ? -1 : 0;
+    for (int i = 0; i < num_parameters; i++) {
-    for (int i = first_parameter; i < num_parameters; i++) {
+      Variable* var = scope()->parameter(i);
-      Variable* var = (i == -1) ? scope()->receiver() : scope()->parameter(i);
       if (var->IsContextSlot()) {
         int parameter_offset = StandardFrameConstants::kCallerSPOffset +
             (num_parameters - 1 - i) * kPointerSize;

src/mips/full-codegen-mips.cc

@@ -135,7 +135,7 @@ void FullCodeGenerator::Generate() {
   // global proxy when called as functions (without an explicit receiver
   // object).
   if (is_sloppy(info->language_mode()) && !info->is_native() &&
-      info->MayUseThis() && info->scope()->has_this_declaration()) {
+      info->MayUseThis()) {
     Label ok;
     int receiver_offset = info->scope()->num_parameters() * kPointerSize;
     __ lw(at, MemOperand(sp, receiver_offset));
@@ -225,9 +225,8 @@ void FullCodeGenerator::Generate() {
     __ sw(v0, MemOperand(fp, StandardFrameConstants::kContextOffset));
     // Copy any necessary parameters into the context.
     int num_parameters = info->scope()->num_parameters();
-    int first_parameter = info->scope()->has_this_declaration() ? -1 : 0;
+    for (int i = 0; i < num_parameters; i++) {
-    for (int i = first_parameter; i < num_parameters; i++) {
+      Variable* var = scope()->parameter(i);
-      Variable* var = (i == -1) ? scope()->receiver() : scope()->parameter(i);
       if (var->IsContextSlot()) {
         int parameter_offset = StandardFrameConstants::kCallerSPOffset +
                                  (num_parameters - 1 - i) * kPointerSize;
@@ -3039,9 +3038,8 @@ void FullCodeGenerator::EmitResolvePossiblyDirectEval(int arg_count) {
   __ lw(t2, MemOperand(fp, JavaScriptFrameConstants::kFunctionOffset));
 
   // t1: the receiver of the enclosing function.
-  Variable* this_var = scope()->LookupThis();
+  int receiver_offset = 2 + info_->scope()->num_parameters();
-  DCHECK_NOT_NULL(this_var);
+  __ lw(t1, MemOperand(fp, receiver_offset * kPointerSize));
-  __ lw(t1, VarOperand(this_var, t1));
 
   // t0: the language mode.
   __ li(t0, Operand(Smi::FromInt(language_mode())));

src/mips/lithium-codegen-mips.cc

@@ -143,8 +143,8 @@ bool LCodeGen::GeneratePrologue() {
     // Sloppy mode functions and builtins need to replace the receiver with the
     // global proxy when called as functions (without an explicit receiver
     // object).
-    if (is_sloppy(info()->language_mode()) && info()->MayUseThis() &&
+    if (is_sloppy(info_->language_mode()) && info()->MayUseThis() &&
-        !info()->is_native() && info()->scope()->has_this_declaration()) {
+        !info_->is_native()) {
       Label ok;
       int receiver_offset = info_->scope()->num_parameters() * kPointerSize;
       __ LoadRoot(at, Heap::kUndefinedValueRootIndex);
@@ -217,9 +217,8 @@ bool LCodeGen::GeneratePrologue() {
     __ sw(v0, MemOperand(fp, StandardFrameConstants::kContextOffset));
     // Copy any necessary parameters into the context.
     int num_parameters = scope()->num_parameters();
-    int first_parameter = scope()->has_this_declaration() ? -1 : 0;
+    for (int i = 0; i < num_parameters; i++) {
-    for (int i = first_parameter; i < num_parameters; i++) {
+      Variable* var = scope()->parameter(i);
-      Variable* var = (i == -1) ? scope()->receiver() : scope()->parameter(i);
       if (var->IsContextSlot()) {
         int parameter_offset = StandardFrameConstants::kCallerSPOffset +
             (num_parameters - 1 - i) * kPointerSize;

src/mips64/full-codegen-mips64.cc

@@ -135,7 +135,7 @@ void FullCodeGenerator::Generate() {
   // global proxy when called as functions (without an explicit receiver
   // object).
   if (is_sloppy(info->language_mode()) && !info->is_native() &&
-      info->MayUseThis() && info->scope()->has_this_declaration()) {
+      info->MayUseThis()) {
     Label ok;
     int receiver_offset = info->scope()->num_parameters() * kPointerSize;
     __ ld(at, MemOperand(sp, receiver_offset));
@@ -222,9 +222,8 @@ void FullCodeGenerator::Generate() {
     __ sd(v0, MemOperand(fp, StandardFrameConstants::kContextOffset));
     // Copy any necessary parameters into the context.
     int num_parameters = info->scope()->num_parameters();
-    int first_parameter = info->scope()->has_this_declaration() ? -1 : 0;
+    for (int i = 0; i < num_parameters; i++) {
-    for (int i = first_parameter; i < num_parameters; i++) {
+      Variable* var = scope()->parameter(i);
-      Variable* var = (i == -1) ? scope()->receiver() : scope()->parameter(i);
       if (var->IsContextSlot()) {
         int parameter_offset = StandardFrameConstants::kCallerSPOffset +
                                  (num_parameters - 1 - i) * kPointerSize;
@@ -3041,9 +3040,8 @@ void FullCodeGenerator::EmitResolvePossiblyDirectEval(int arg_count) {
   __ ld(a6, MemOperand(fp, JavaScriptFrameConstants::kFunctionOffset));
 
   // a5: the receiver of the enclosing function.
-  Variable* this_var = scope()->LookupThis();
+  int receiver_offset = 2 + info_->scope()->num_parameters();
-  DCHECK_NOT_NULL(this_var);
+  __ ld(a5, MemOperand(fp, receiver_offset * kPointerSize));
-  __ ld(a5, VarOperand(this_var, a5));
 
   // a4: the language mode.
   __ li(a4, Operand(Smi::FromInt(language_mode())));

src/mips64/lithium-codegen-mips64.cc

@@ -118,8 +118,8 @@ bool LCodeGen::GeneratePrologue() {
     // Sloppy mode functions and builtins need to replace the receiver with the
     // global proxy when called as functions (without an explicit receiver
     // object).
-    if (is_sloppy(info()->language_mode()) && info()->MayUseThis() &&
+    if (is_sloppy(info_->language_mode()) && info()->MayUseThis() &&
-        !info()->is_native() && info()->scope()->has_this_declaration()) {
+        !info_->is_native()) {
       Label ok;
       int receiver_offset = info_->scope()->num_parameters() * kPointerSize;
       __ LoadRoot(at, Heap::kUndefinedValueRootIndex);
@@ -192,9 +192,8 @@ bool LCodeGen::GeneratePrologue() {
     __ sd(v0, MemOperand(fp, StandardFrameConstants::kContextOffset));
     // Copy any necessary parameters into the context.
     int num_parameters = scope()->num_parameters();
-    int first_parameter = scope()->has_this_declaration() ? -1 : 0;
+    for (int i = 0; i < num_parameters; i++) {
-    for (int i = first_parameter; i < num_parameters; i++) {
+      Variable* var = scope()->parameter(i);
-      Variable* var = (i == -1) ? scope()->receiver() : scope()->parameter(i);
       if (var->IsContextSlot()) {
         int parameter_offset = StandardFrameConstants::kCallerSPOffset +
             (num_parameters - 1 - i) * kPointerSize;

src/parser.cc

@@ -741,9 +741,7 @@ const AstRawString* ParserTraits::GetNextSymbol(Scanner* scanner) {
 
 Expression* ParserTraits::ThisExpression(Scope* scope, AstNodeFactory* factory,
                                          int pos) {
-  return scope->NewUnresolved(factory,
+  return factory->NewVariableProxy(scope->receiver(), pos);
-                              parser_->ast_value_factory()->this_string(),
-                              Variable::THIS, pos, pos + 4);
 }
 
 Expression* ParserTraits::SuperReference(Scope* scope, AstNodeFactory* factory,
@@ -791,8 +789,7 @@ Expression* ParserTraits::ExpressionFromIdentifier(const AstRawString* name,
                                                    Scope* scope,
                                                    AstNodeFactory* factory) {
   if (parser_->fni_ != NULL) parser_->fni_->PushVariableName(name);
-  return scope->NewUnresolved(factory, name, Variable::NORMAL, start_position,
+  return scope->NewUnresolved(factory, name, start_position, end_position);
-                              end_position);
 }
 
 
@@ -971,8 +968,6 @@ FunctionLiteral* Parser::DoParseProgram(ParseInfo* info) {
 
   FunctionLiteral* result = NULL;
   {
-    // TODO(wingo): Add an outer GLOBAL_SCOPE corresponding to the native
-    // context, which will have the "this" binding for script scopes.
     Scope* scope = NewScope(scope_, SCRIPT_SCOPE);
     info->set_script_scope(scope);
     if (!info->context().is_null() && !info->context()->IsNativeContext()) {
@@ -1923,9 +1918,9 @@ VariableProxy* Parser::NewUnresolved(const AstRawString* name,
   // scope.
   // Let/const variables in harmony mode are always added to the immediately
   // enclosing scope.
-  return DeclarationScope(mode)->NewUnresolved(
+  return DeclarationScope(mode)->NewUnresolved(factory(), name,
-      factory(), name, Variable::NORMAL, scanner()->location().beg_pos,
+                                               scanner()->location().beg_pos,
-      scanner()->location().end_pos);
+                                               scanner()->location().end_pos);
 }
 
 
@@ -3438,8 +3433,8 @@ Statement* Parser::ParseForStatement(ZoneList<const AstRawString*>* labels,
         Expression* enumerable = ParseExpression(true, CHECK_OK);
         Expect(Token::RPAREN, CHECK_OK);
 
-        VariableProxy* each = scope_->NewUnresolved(
+        VariableProxy* each =
-            factory(), name, Variable::NORMAL, each_beg_pos, each_end_pos);
+            scope_->NewUnresolved(factory(), name, each_beg_pos, each_end_pos);
         Statement* body = ParseSubStatement(NULL, CHECK_OK);
         InitializeForEachStatement(loop, each, enumerable, body);
         Block* result =
@@ -3520,8 +3515,8 @@ Statement* Parser::ParseForStatement(ZoneList<const AstRawString*>* labels,
         scope_ = for_scope;
         Expect(Token::RPAREN, CHECK_OK);
 
-        VariableProxy* each = scope_->NewUnresolved(
+        VariableProxy* each =
-            factory(), name, Variable::NORMAL, each_beg_pos, each_end_pos);
+            scope_->NewUnresolved(factory(), name, each_beg_pos, each_end_pos);
         Statement* body = ParseSubStatement(NULL, CHECK_OK);
         Block* body_block =
             factory()->NewBlock(NULL, 3, false, RelocInfo::kNoPosition);

src/ppc/full-codegen-ppc.cc

@@ -124,7 +124,7 @@ void FullCodeGenerator::Generate() {
   // global proxy when called as functions (without an explicit receiver
   // object).
   if (is_sloppy(info->language_mode()) && !info->is_native() &&
-      info->MayUseThis() && info->scope()->has_this_declaration()) {
+      info->MayUseThis()) {
     Label ok;
     int receiver_offset = info->scope()->num_parameters() * kPointerSize;
     __ LoadP(r5, MemOperand(sp, receiver_offset), r0);
@@ -221,9 +221,8 @@ void FullCodeGenerator::Generate() {
     __ StoreP(r3, MemOperand(fp, StandardFrameConstants::kContextOffset));
     // Copy any necessary parameters into the context.
     int num_parameters = info->scope()->num_parameters();
-    int first_parameter = info->scope()->has_this_declaration() ? -1 : 0;
+    for (int i = 0; i < num_parameters; i++) {
-    for (int i = first_parameter; i < num_parameters; i++) {
+      Variable* var = scope()->parameter(i);
-      Variable* var = (i == -1) ? scope()->receiver() : scope()->parameter(i);
       if (var->IsContextSlot()) {
         int parameter_offset = StandardFrameConstants::kCallerSPOffset +
                                (num_parameters - 1 - i) * kPointerSize;
@@ -3051,9 +3050,8 @@ void FullCodeGenerator::EmitResolvePossiblyDirectEval(int arg_count) {
   __ LoadP(r7, MemOperand(fp, JavaScriptFrameConstants::kFunctionOffset));
 
   // r6: the receiver of the enclosing function.
-  Variable* this_var = scope()->LookupThis();
+  int receiver_offset = 2 + info_->scope()->num_parameters();
-  DCHECK_NOT_NULL(this_var);
+  __ LoadP(r6, MemOperand(fp, receiver_offset * kPointerSize), r0);
-  GetVar(r6, this_var);
 
   // r5: language mode.
   __ LoadSmiLiteral(r5, Smi::FromInt(language_mode()));

src/ppc/lithium-codegen-ppc.cc

@@ -118,8 +118,8 @@ bool LCodeGen::GeneratePrologue() {
     // Sloppy mode functions and builtins need to replace the receiver with the
     // global proxy when called as functions (without an explicit receiver
     // object).
-    if (is_sloppy(info_->language_mode()) && info_->MayUseThis() &&
+    if (is_sloppy(info_->language_mode()) && info()->MayUseThis() &&
-        !info_->is_native() && info_->scope()->has_this_declaration()) {
+        !info_->is_native()) {
       Label ok;
       int receiver_offset = info_->scope()->num_parameters() * kPointerSize;
       __ LoadP(r5, MemOperand(sp, receiver_offset));
@@ -199,9 +199,8 @@ bool LCodeGen::GeneratePrologue() {
     __ StoreP(r3, MemOperand(fp, StandardFrameConstants::kContextOffset));
     // Copy any necessary parameters into the context.
     int num_parameters = scope()->num_parameters();
-    int first_parameter = scope()->has_this_declaration() ? -1 : 0;
+    for (int i = 0; i < num_parameters; i++) {
-    for (int i = first_parameter; i < num_parameters; i++) {
+      Variable* var = scope()->parameter(i);
-      Variable* var = (i == -1) ? scope()->receiver() : scope()->parameter(i);
       if (var->IsContextSlot()) {
         int parameter_offset = StandardFrameConstants::kCallerSPOffset +
                                (num_parameters - 1 - i) * kPointerSize;

src/preparser.h

@@ -2282,6 +2282,7 @@ ParserBase<Traits>::ParsePrimaryExpression(ExpressionClassifier* classifier,
           break;
         }
       }
+      scope_->RecordThisUsage();
       result = this->ThisExpression(scope_, factory(), beg_pos);
       break;
     }
@@ -3354,6 +3355,7 @@ ParserBase<Traits>::ParseStrongInitializationExpression(
   Consume(Token::THIS);
   int pos = position();
   function_state_->set_this_location(scanner()->location());
+  scope_->RecordThisUsage();
   ExpressionT this_expr = this->ThisExpression(scope_, factory(), pos);
 
   ExpressionT left = this->EmptyExpression();

src/runtime/runtime-debug.cc

@@ -1475,21 +1475,16 @@ class ScopeIterator {
       context_ = Handle<Context>();
       return;
     }
-    if (scope_type == ScopeTypeScript) {
+    if (scope_type == ScopeTypeScript) seen_script_scope_ = true;
-      seen_script_scope_ = true;
+    if (nested_scope_chain_.is_empty()) {
-      if (context_->IsScriptContext()) {
+      if (scope_type == ScopeTypeScript) {
+        if (context_->IsScriptContext()) {
+          context_ = Handle<Context>(context_->previous(), isolate_);
+        }
+        CHECK(context_->IsNativeContext());
+      } else {
         context_ = Handle<Context>(context_->previous(), isolate_);
       }
-      if (!nested_scope_chain_.is_empty()) {
-        DCHECK_EQ(nested_scope_chain_.last()->scope_type(), SCRIPT_SCOPE);
-        nested_scope_chain_.RemoveLast();
-        DCHECK(nested_scope_chain_.is_empty());
-      }
-      CHECK(context_->IsNativeContext());
-      return;
-    }
-    if (nested_scope_chain_.is_empty()) {
-      context_ = Handle<Context>(context_->previous(), isolate_);
     } else {
       if (nested_scope_chain_.last()->HasContext()) {
         DCHECK(context_->previous() != NULL);

src/runtime/runtime-scopes.cc

@@ -248,12 +248,6 @@ RUNTIME_FUNCTION(Runtime_DeclareLookupSlot) {
         JSGlobalObject::cast(context_arg->extension()), isolate);
     return DeclareGlobals(isolate, global, name, value, attr, is_var, is_const,
                           is_function);
-  } else if (context->IsScriptContext()) {
-    DCHECK(context->global_object()->IsJSGlobalObject());
-    Handle<JSGlobalObject> global(
-        JSGlobalObject::cast(context->global_object()), isolate);
-    return DeclareGlobals(isolate, global, name, value, attr, is_var, is_const,
-                          is_function);
   }
 
   if (attributes != ABSENT) {
@@ -329,12 +323,8 @@ RUNTIME_FUNCTION(Runtime_InitializeLegacyConstLookupSlot) {
   // meanwhile. If so, re-introduce the variable in the context extension.
   if (attributes == ABSENT) {
     Handle<Context> declaration_context(context_arg->declaration_context());
-    if (declaration_context->IsScriptContext()) {
+    DCHECK(declaration_context->has_extension());
-      holder = handle(declaration_context->global_object(), isolate);
+    holder = handle(declaration_context->extension(), isolate);
-    } else {
-      DCHECK(declaration_context->has_extension());
-      holder = handle(declaration_context->extension(), isolate);
-    }
     CHECK(holder->IsJSObject());
   } else {
     // For JSContextExtensionObjects, the initializer can be run multiple times
@@ -638,12 +628,8 @@ RUNTIME_FUNCTION(Runtime_NewScriptContext) {
       FindNameClash(scope_info, global_object, script_context_table);
   if (isolate->has_pending_exception()) return name_clash_result;
 
-  // Script contexts have a canonical empty function as their closure, not the
-  // anonymous closure containing the global code.  See
-  // FullCodeGenerator::PushFunctionArgumentForContextAllocation.
-  Handle<JSFunction> closure(native_context->closure());
   Handle<Context> result =
-      isolate->factory()->NewScriptContext(closure, scope_info);
+      isolate->factory()->NewScriptContext(function, scope_info);
 
   DCHECK(function->context() == isolate->context());
   DCHECK(function->context()->global_object() == result->global_object());

src/scopeinfo.cc

@@ -317,8 +317,7 @@ bool ScopeInfo::LocalIsSynthetic(int var) {
   // with user declarations, the current temporaries like .generator_object and
   // .result start with a dot, so we can use that as a flag. It's a hack!
   Handle<String> name(LocalName(var));
-  return (name->length() > 0 && name->Get(0) == '.') ||
+  return name->length() > 0 && name->Get(0) == '.';
-         name->Equals(*GetIsolate()->factory()->this_string());
 }
 
 

src/scopes.cc

@@ -165,6 +165,7 @@ void Scope::SetDefaults(ScopeType scope_type, Scope* outer_scope,
   scope_calls_eval_ = false;
   scope_uses_arguments_ = false;
   scope_uses_super_property_ = false;
+  scope_uses_this_ = false;
   asm_module_ = false;
   asm_function_ = outer_scope != NULL && outer_scope->asm_module_;
   // Inherit the language mode from the parent scope.
@@ -172,6 +173,7 @@ void Scope::SetDefaults(ScopeType scope_type, Scope* outer_scope,
   outer_scope_calls_sloppy_eval_ = false;
   inner_scope_calls_eval_ = false;
   inner_scope_uses_arguments_ = false;
+  inner_scope_uses_this_ = false;
   inner_scope_uses_super_property_ = false;
   force_eager_compilation_ = false;
   force_context_allocation_ = (outer_scope != NULL && !is_function_scope())
@@ -307,16 +309,22 @@ void Scope::Initialize() {
     scope_inside_with_ = is_with_scope();
   }
 
-  // Declare convenience variables and the receiver.
+  // Declare convenience variables.
+  // Declare and allocate receiver (even for the script scope, and even
+  // if naccesses_ == 0).
+  // NOTE: When loading parameters in the script scope, we must take
+  // care not to access them as properties of the global object, but
+  // instead load them directly from the stack. Currently, the only
+  // such parameter is 'this' which is passed on the stack when
+  // invoking scripts
   if (is_declaration_scope()) {
     DCHECK(!subclass_constructor || is_function_scope());
-    if (has_this_declaration()) {
+    Variable* var = variables_.Declare(
-      Variable* var = variables_.Declare(
+        this, ast_value_factory_->this_string(),
-          this, ast_value_factory_->this_string(),
+        subclass_constructor ? CONST : VAR, Variable::THIS,
-          subclass_constructor ? CONST : VAR, Variable::THIS,
+        subclass_constructor ? kNeedsInitialization : kCreatedInitialized);
-          subclass_constructor ? kNeedsInitialization : kCreatedInitialized);
+    var->AllocateTo(Variable::PARAMETER, -1);
-      receiver_ = var;
+    receiver_ = var;
-    }
 
     if (subclass_constructor) {
       new_target_ =
@@ -325,6 +333,9 @@ void Scope::Initialize() {
       new_target_->AllocateTo(Variable::PARAMETER, -2);
       new_target_->set_is_used();
     }
+  } else {
+    DCHECK(outer_scope() != NULL);
+    receiver_ = outer_scope()->receiver();
   }
 
   if (is_function_scope() && !is_arrow_scope()) {
@@ -369,6 +380,7 @@ Scope* Scope::FinalizeBlockScope() {
   // Propagate usage flags to outer scope.
   if (uses_arguments()) outer_scope_->RecordArgumentsUsage();
   if (uses_super_property()) outer_scope_->RecordSuperPropertyUsage();
+  if (uses_this()) outer_scope_->RecordThisUsage();
   if (scope_calls_eval_) outer_scope_->RecordEvalCall();
 
   return NULL;
@@ -918,11 +930,13 @@ void Scope::Print(int n) {
   if (scope_uses_arguments_) Indent(n1, "// scope uses 'arguments'\n");
   if (scope_uses_super_property_)
     Indent(n1, "// scope uses 'super' property\n");
+  if (scope_uses_this_) Indent(n1, "// scope uses 'this'\n");
   if (inner_scope_uses_arguments_) {
     Indent(n1, "// inner scope uses 'arguments'\n");
   }
   if (inner_scope_uses_super_property_)
     Indent(n1, "// inner scope uses 'super' property\n");
+  if (inner_scope_uses_this_) Indent(n1, "// inner scope uses 'this'\n");
   if (outer_scope_calls_sloppy_eval_) {
     Indent(n1, "// outer scope calls 'eval' in sloppy context\n");
   }
@@ -1035,11 +1049,7 @@ Variable* Scope::LookupRecursive(VariableProxy* proxy,
     DCHECK(is_script_scope());
   }
 
-  // "this" can't be shadowed by "eval"-introduced bindings or by "with" scopes.
+  if (is_with_scope()) {
-  // TODO(wingo): There are other variables in this category; add them.
-  bool name_can_be_shadowed = var == nullptr || !var->is_this();
-
-  if (is_with_scope() && name_can_be_shadowed) {
     DCHECK(!already_resolved());
     // The current scope is a with scope, so the variable binding can not be
     // statically resolved. However, note that it was necessary to do a lookup
@@ -1050,7 +1060,7 @@ Variable* Scope::LookupRecursive(VariableProxy* proxy,
     if (var != NULL && proxy->is_assigned()) var->set_maybe_assigned();
     *binding_kind = DYNAMIC_LOOKUP;
     return NULL;
-  } else if (calls_sloppy_eval() && name_can_be_shadowed) {
+  } else if (calls_sloppy_eval()) {
     // A variable binding may have been found in an outer scope, but the current
     // scope makes a sloppy 'eval' call, so the found variable may not be
     // the correct one (the 'eval' may introduce a binding with the same name).
@@ -1282,6 +1292,9 @@ void Scope::PropagateScopeInfo(bool outer_scope_calls_sloppy_eval ) {
           inner->inner_scope_uses_super_property_) {
         inner_scope_uses_super_property_ = true;
       }
+      if (inner->scope_uses_this_ || inner->inner_scope_uses_this_) {
+        inner_scope_uses_this_ = true;
+      }
     }
     if (inner->force_eager_compilation_) {
       force_eager_compilation_ = true;
@@ -1402,40 +1415,24 @@ void Scope::AllocateParameterLocals(Isolate* isolate) {
       // Force context allocation of the parameter.
       var->ForceContextAllocation();
     }
-    AllocateParameter(var, i);
-  }
-}
 
-
+    if (MustAllocate(var)) {
-void Scope::AllocateParameter(Variable* var, int index) {
+      if (MustAllocateInContext(var)) {
-  if (MustAllocate(var)) {
+        DCHECK(var->IsUnallocated() || var->IsContextSlot());
-    if (MustAllocateInContext(var)) {
+        if (var->IsUnallocated()) {
-      DCHECK(var->IsUnallocated() || var->IsContextSlot());
+          AllocateHeapSlot(var);
-      if (var->IsUnallocated()) {
+        }
-        AllocateHeapSlot(var);
+      } else {
-      }
+        DCHECK(var->IsUnallocated() || var->IsParameter());
-    } else {
+        if (var->IsUnallocated()) {
-      DCHECK(var->IsUnallocated() || var->IsParameter());
+          var->AllocateTo(Variable::PARAMETER, i);
-      if (var->IsUnallocated()) {
+        }
-        var->AllocateTo(Variable::PARAMETER, index);
       }
     }
   }
 }
 
 
-void Scope::AllocateReceiver() {
-  DCHECK_NOT_NULL(receiver());
-  DCHECK_EQ(receiver()->scope(), this);
-
-  if (has_forced_context_allocation()) {
-    // Force context allocation of the receiver.
-    receiver()->ForceContextAllocation();
-  }
-  AllocateParameter(receiver(), -1);
-}
-
-
 void Scope::AllocateNonParameterLocal(Isolate* isolate, Variable* var) {
   DCHECK(var->scope() == this);
   DCHECK(!var->IsVariable(isolate->factory()->dot_result_string()) ||
@@ -1505,7 +1502,6 @@ void Scope::AllocateVariablesRecursively(Isolate* isolate) {
   // Allocate variables for this scope.
   // Parameters must be allocated first, if any.
   if (is_function_scope()) AllocateParameterLocals(isolate);
-  if (has_this_declaration()) AllocateReceiver();
   AllocateNonParameterLocals(isolate);
 
   // Force allocation of a context for this scope if necessary. For a 'with'

src/scopes.h

@@ -144,15 +144,14 @@ class Scope: public ZoneObject {
   // Create a new unresolved variable.
   VariableProxy* NewUnresolved(AstNodeFactory* factory,
                                const AstRawString* name,
-                               Variable::Kind kind = Variable::NORMAL,
                                int start_position = RelocInfo::kNoPosition,
                                int end_position = RelocInfo::kNoPosition) {
     // Note that we must not share the unresolved variables with
     // the same name because they may be removed selectively via
     // RemoveUnresolved().
     DCHECK(!already_resolved());
-    VariableProxy* proxy =
+    VariableProxy* proxy = factory->NewVariableProxy(
-        factory->NewVariableProxy(name, kind, start_position, end_position);
+        name, Variable::NORMAL, start_position, end_position);
     unresolved_.Add(proxy, zone_);
     return proxy;
   }
@@ -218,6 +217,9 @@ class Scope: public ZoneObject {
   // Inform the scope that the corresponding code uses "super".
   void RecordSuperPropertyUsage() { scope_uses_super_property_ = true; }
 
+  // Inform the scope that the corresponding code uses "this".
+  void RecordThisUsage() { scope_uses_this_ = true; }
+
   // Set the language mode flag (unless disabled by a global flag).
   void SetLanguageMode(LanguageMode language_mode) {
     language_mode_ = language_mode;
@@ -321,6 +323,10 @@ class Scope: public ZoneObject {
   bool inner_uses_super_property() const {
     return inner_scope_uses_super_property_;
   }
+  // Does this scope access "this".
+  bool uses_this() const { return scope_uses_this_; }
+  // Does any inner scope access "this".
+  bool inner_uses_this() const { return inner_scope_uses_this_; }
 
   const Scope* NearestOuterEvalScope() const {
     if (is_eval_scope()) return this;
@@ -340,21 +346,7 @@ class Scope: public ZoneObject {
   LanguageMode language_mode() const { return language_mode_; }
 
   // The variable corresponding to the 'this' value.
-  Variable* receiver() {
+  Variable* receiver() { return receiver_; }
-    DCHECK(has_this_declaration());
-    DCHECK_NOT_NULL(receiver_);
-    return receiver_;
-  }
-
-  Variable* LookupThis() { return Lookup(ast_value_factory_->this_string()); }
-
-  // TODO(wingo): Add a GLOBAL_SCOPE scope type which will lexically allocate
-  // "this" (and no other variable) on the native context.  Script scopes then
-  // will not have a "this" declaration.
-  bool has_this_declaration() const {
-    return (is_function_scope() && !is_arrow_scope()) || is_module_scope() ||
-           is_script_scope();
-  }
 
   // The variable corresponding to the 'new.target' value.
   Variable* new_target_var() { return new_target_; }
@@ -585,6 +577,8 @@ class Scope: public ZoneObject {
   bool scope_uses_arguments_;
   // This scope uses "super" property ('super.foo').
   bool scope_uses_super_property_;
+  // This scope uses "this".
+  bool scope_uses_this_;
   // This scope contains an "use asm" annotation.
   bool asm_module_;
   // This scope's outer context is an asm module.
@@ -600,6 +594,7 @@ class Scope: public ZoneObject {
   bool inner_scope_calls_eval_;
   bool inner_scope_uses_arguments_;
   bool inner_scope_uses_super_property_;
+  bool inner_scope_uses_this_;
   bool force_eager_compilation_;
   bool force_context_allocation_;
 
@@ -711,8 +706,6 @@ class Scope: public ZoneObject {
   void AllocateNonParameterLocal(Isolate* isolate, Variable* var);
   void AllocateNonParameterLocals(Isolate* isolate);
   void AllocateVariablesRecursively(Isolate* isolate);
-  void AllocateParameter(Variable* var, int index);
-  void AllocateReceiver();
   void AllocateModules();
 
   // Resolve and fill in the allocation information for all variables

src/variables.cc

@@ -59,8 +59,8 @@ bool Variable::IsGlobalObjectProperty() const {
   // Temporaries are never global, they must always be allocated in the
   // activation frame.
   return (IsDynamicVariableMode(mode_) ||
-          (IsDeclaredVariableMode(mode_) && !IsLexicalVariableMode(mode_))) &&
+          (IsDeclaredVariableMode(mode_) && !IsLexicalVariableMode(mode_)))
-         scope_ != NULL && scope_->is_script_scope() && !is_this();
+      && scope_ != NULL && scope_->is_script_scope();
 }
 
 

src/x64/full-codegen-x64.cc

@@ -115,7 +115,7 @@ void FullCodeGenerator::Generate() {
   // global proxy when called as functions (without an explicit receiver
   // object).
   if (is_sloppy(info->language_mode()) && !info->is_native() &&
-      info->MayUseThis() && info->scope()->has_this_declaration()) {
+      info->MayUseThis()) {
     Label ok;
     // +1 for return address.
     StackArgumentsAccessor args(rsp, info->scope()->num_parameters());
@@ -209,9 +209,8 @@ void FullCodeGenerator::Generate() {
 
     // Copy any necessary parameters into the context.
     int num_parameters = info->scope()->num_parameters();
-    int first_parameter = info->scope()->has_this_declaration() ? -1 : 0;
+    for (int i = 0; i < num_parameters; i++) {
-    for (int i = first_parameter; i < num_parameters; i++) {
+      Variable* var = scope()->parameter(i);
-      Variable* var = (i == -1) ? scope()->receiver() : scope()->parameter(i);
       if (var->IsContextSlot()) {
         int parameter_offset = StandardFrameConstants::kCallerSPOffset +
             (num_parameters - 1 - i) * kPointerSize;
@@ -2962,9 +2961,8 @@ void FullCodeGenerator::EmitResolvePossiblyDirectEval(int arg_count) {
   __ Push(Operand(rbp, JavaScriptFrameConstants::kFunctionOffset));
 
   // Push the receiver of the enclosing function and do runtime call.
-  Variable* this_var = scope()->LookupThis();
+  StackArgumentsAccessor args(rbp, info_->scope()->num_parameters());
-  DCHECK_NOT_NULL(this_var);
+  __ Push(args.GetReceiverOperand());
-  __ Push(VarOperand(this_var, rcx));
 
   // Push the language mode.
   __ Push(Smi::FromInt(language_mode()));

src/x64/lithium-codegen-x64.cc

@@ -129,8 +129,8 @@ bool LCodeGen::GeneratePrologue() {
 
     // Sloppy mode functions need to replace the receiver with the global proxy
     // when called as functions (without an explicit receiver object).
-    if (is_sloppy(info()->language_mode()) && info()->MayUseThis() &&
+    if (is_sloppy(info_->language_mode()) && info()->MayUseThis() &&
-        !info()->is_native() && info()->scope()->has_this_declaration()) {
+        !info_->is_native()) {
       Label ok;
       StackArgumentsAccessor args(rsp, scope()->num_parameters());
       __ movp(rcx, args.GetReceiverOperand());
@@ -213,9 +213,8 @@ bool LCodeGen::GeneratePrologue() {
 
     // Copy any necessary parameters into the context.
     int num_parameters = scope()->num_parameters();
-    int first_parameter = scope()->has_this_declaration() ? -1 : 0;
+    for (int i = 0; i < num_parameters; i++) {
-    for (int i = first_parameter; i < num_parameters; i++) {
+      Variable* var = scope()->parameter(i);
-      Variable* var = (i == -1) ? scope()->receiver() : scope()->parameter(i);
       if (var->IsContextSlot()) {
         int parameter_offset = StandardFrameConstants::kCallerSPOffset +
             (num_parameters - 1 - i) * kPointerSize;

test/cctest/test-parsing.cc

@@ -962,6 +962,7 @@ TEST(ScopeUsesArgumentsSuperThis) {
     THIS = 1 << 2,
     INNER_ARGUMENTS = 1 << 3,
     INNER_SUPER_PROPERTY = 1 << 4,
+    INNER_THIS = 1 << 5
   };
 
   static const struct {
@@ -976,7 +977,7 @@ TEST(ScopeUsesArgumentsSuperThis) {
     {"return this + arguments[0]", ARGUMENTS | THIS},
     {"return this + arguments[0] + super.x",
      ARGUMENTS | SUPER_PROPERTY | THIS},
-    {"return x => this + x", THIS},
+    {"return x => this + x", INNER_THIS},
     {"return x => super.f() + x", INNER_SUPER_PROPERTY},
     {"this.foo = 42;", THIS},
     {"this.foo();", THIS},
@@ -990,7 +991,9 @@ TEST(ScopeUsesArgumentsSuperThis) {
     {"while (true) { while (true) { while (true) return this } }", THIS},
     {"while (true) { while (true) { while (true) return super.f() } }",
      SUPER_PROPERTY},
-    {"if (1) { return () => { while (true) new this() } }", THIS},
+    {"if (1) { return () => { while (true) new this() } }", INNER_THIS},
+    // Note that propagation of the inner_uses_this() value does not
+    // cross boundaries of normal functions onto parent scopes.
     {"return function (x) { return this + x }", NONE},
     {"return { m(x) { return super.m() + x } }", NONE},
     {"var x = function () { this.foo = 42 };", NONE},
@@ -1001,10 +1004,10 @@ TEST(ScopeUsesArgumentsSuperThis) {
     {"return { m(x) { return () => super.m() } }", NONE},
     // Flags must be correctly set when using block scoping.
     {"\"use strict\"; while (true) { let x; this, arguments; }",
-     INNER_ARGUMENTS | THIS},
+     INNER_ARGUMENTS | INNER_THIS},
     {"\"use strict\"; while (true) { let x; this, super.f(), arguments; }",
-     INNER_ARGUMENTS | INNER_SUPER_PROPERTY | THIS},
+     INNER_ARGUMENTS | INNER_SUPER_PROPERTY | INNER_THIS},
-    {"\"use strict\"; if (foo()) { let x; this.f() }", THIS},
+    {"\"use strict\"; if (foo()) { let x; this.f() }", INNER_THIS},
     {"\"use strict\"; if (foo()) { let x; super.f() }",
      INNER_SUPER_PROPERTY},
     {"\"use strict\"; if (1) {"
@@ -1068,15 +1071,13 @@ TEST(ScopeUsesArgumentsSuperThis) {
                scope->uses_arguments());
       CHECK_EQ((source_data[i].expected & SUPER_PROPERTY) != 0,
                scope->uses_super_property());
-      if ((source_data[i].expected & THIS) != 0) {
+      CHECK_EQ((source_data[i].expected & THIS) != 0, scope->uses_this());
-        // Currently the is_used() flag is conservative; all variables in a
-        // script scope are marked as used.
-        CHECK(scope->LookupThis()->is_used());
-      }
       CHECK_EQ((source_data[i].expected & INNER_ARGUMENTS) != 0,
                scope->inner_uses_arguments());
       CHECK_EQ((source_data[i].expected & INNER_SUPER_PROPERTY) != 0,
                scope->inner_uses_super_property());
+      CHECK_EQ((source_data[i].expected & INNER_THIS) != 0,
+               scope->inner_uses_this());
     }
   }
 }

test/cctest/test-serialize.cc

@@ -628,7 +628,7 @@ UNINITIALIZED_DEPENDENT_TEST(CustomContextDeserialization,
       root =
           deserializer.DeserializePartial(isolate, global_proxy,
                                           &outdated_contexts).ToHandleChecked();
-      CHECK_EQ(3, outdated_contexts->length());
+      CHECK_EQ(2, outdated_contexts->length());
       CHECK(root->IsContext());
       Handle<Context> context = Handle<Context>::cast(root);
       CHECK(context->global_proxy() == *global_proxy);

test/mjsunit/debug-scopes.js

@@ -167,10 +167,6 @@ function CheckScopeContent(content, number, exec_state) {
   if (!scope.scopeObject().property('arguments').isUndefined()) {
     scope_size--;
   }
-  // Ditto for 'this'.
-  if (!scope.scopeObject().property('this').isUndefined()) {
-    scope_size--;
-  }
   // Skip property with empty name.
   if (!scope.scopeObject().property('').isUndefined()) {
     scope_size--;

test/mjsunit/harmony/arrow-functions-this.js

@@ -1,81 +0,0 @@
-// Copyright 2015 the V8 project authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-// Flags: --harmony-arrow-functions
-
-var object = {};
-var global = this;
-var call = Function.call.bind(Function.call);
-
-var globalSloppyArrow = () => this;
-var globalStrictArrow = () => { "use strict"; return this; };
-var globalSloppyArrowEval = (s) => eval(s);
-var globalStrictArrowEval = (s) => { "use strict"; return eval(s); };
-
-var sloppyFunctionArrow = function() {
-  return (() => this)();
-};
-var strictFunctionArrow = function() {
-  "use strict";
-  return (() => this)();
-};
-var sloppyFunctionEvalArrow = function() {
-  return eval("(() => this)()");
-};
-var strictFunctionEvalArrow = function() {
-  "use strict";
-  return eval("(() => this)()");
-};
-var sloppyFunctionArrowEval = function(s) {
-  return (() => eval(s))();
-};
-var strictFunctionArrowEval = function(s) {
-  "use strict";
-  return (() => eval(s))();
-};
-
-var withObject = { 'this': object }
-var arrowInsideWith, arrowInsideWithEval;
-with (withObject) {
-  arrowInsideWith = () => this;
-  arrowInsideWithEval = (s) => eval(s);
-}
-
-assertEquals(global, call(globalSloppyArrow, object));
-assertEquals(global, call(globalStrictArrow, object));
-assertEquals(global, call(globalSloppyArrowEval, object, "this"));
-assertEquals(global, call(globalStrictArrowEval, object, "this"));
-assertEquals(global, call(globalSloppyArrowEval, object, "(() => this)()"));
-assertEquals(global, call(globalStrictArrowEval, object, "(() => this)()"));
-
-assertEquals(object, call(sloppyFunctionArrow, object));
-assertEquals(global, call(sloppyFunctionArrow, undefined));
-assertEquals(object, call(strictFunctionArrow, object));
-assertEquals(undefined, call(strictFunctionArrow, undefined));
-
-assertEquals(object, call(sloppyFunctionEvalArrow, object));
-assertEquals(global, call(sloppyFunctionEvalArrow, undefined));
-assertEquals(object, call(strictFunctionEvalArrow, object));
-assertEquals(undefined, call(strictFunctionEvalArrow, undefined));
-
-assertEquals(object, call(sloppyFunctionArrowEval, object, "this"));
-assertEquals(global, call(sloppyFunctionArrowEval, undefined, "this"));
-assertEquals(object, call(strictFunctionArrowEval, object, "this"));
-assertEquals(undefined, call(strictFunctionArrowEval, undefined, "this"));
-
-assertEquals(object,
-             call(sloppyFunctionArrowEval, object, "(() => this)()"));
-assertEquals(global,
-             call(sloppyFunctionArrowEval, undefined, "(() => this)()"));
-assertEquals(object,
-             call(strictFunctionArrowEval, object, "(() => this)()"));
-assertEquals(undefined,
-             call(strictFunctionArrowEval, undefined, "(() => this)()"));
-
-assertEquals(global, call(arrowInsideWith, undefined));
-assertEquals(global, call(arrowInsideWith, object));
-assertEquals(global, call(arrowInsideWithEval, undefined, "this"));
-assertEquals(global, call(arrowInsideWithEval, object, "this"));
-assertEquals(global, call(arrowInsideWithEval, undefined, "(() => this)()"));
-assertEquals(global, call(arrowInsideWithEval, object, "(() => this)()"));

test/mjsunit/testcfg.py

@@ -35,7 +35,6 @@ FLAGS_PATTERN = re.compile(r"//\s+Flags:(.*)")
 FILES_PATTERN = re.compile(r"//\s+Files:(.*)")
 SELF_SCRIPT_PATTERN = re.compile(r"//\s+Env: TEST_FILE_NAME")
 MODULE_PATTERN = re.compile(r"^// MODULE$", flags=re.MULTILINE)
-NO_HARNESS_PATTERN = re.compile(r"^// NO HARNESS$", flags=re.MULTILINE)
 
 
 class MjsunitTestSuite(testsuite.TestSuite):
@@ -80,7 +79,7 @@ class MjsunitTestSuite(testsuite.TestSuite):
       env = ["-e", "TEST_FILE_NAME=\"%s\"" % testfilename.replace("\\", "\\\\")]
       files = env + files
 
-    if not context.no_harness and not NO_HARNESS_PATTERN.search(source):
+    if not context.no_harness:
       files.append(os.path.join(self.root, "mjsunit.js"))
 
     if MODULE_PATTERN.search(source):

test/mjsunit/this-dynamic-lookup.js

@@ -1,10 +0,0 @@
-// Copyright 2015 the V8 project authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-// Flags: --harmony-arrow-functions
-// NO HARNESS
-
-var globalEval = eval;
-globalEval("this; eval('42')");
-globalEval("eval('42'); this");