[async-await] (simpler) fix for Return in try/finally in async functions

src/ast/scopes.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/ast/scopes.h"
 
 #include <set>
 
 #include "src/accessors.h"
 #include "src/ast/ast.h"
@@ skipping 279 matching lines @@
   asm_module_ = false;
   asm_function_ = false;
   force_eager_compilation_ = false;
   has_arguments_parameter_ = false;
   scope_uses_super_property_ = false;
   has_rest_ = false;
   receiver_ = nullptr;
   new_target_ = nullptr;
   function_ = nullptr;
   arguments_ = nullptr;
-  this_function_ = nullptr;
+  rare_data_ = nullptr;
   should_eager_compile_ = false;
   was_lazily_parsed_ = false;
 #ifdef DEBUG
   DeclarationScope* outer_declaration_scope =
       outer_scope_ ? outer_scope_->GetDeclarationScope() : nullptr;
   is_being_lazily_parsed_ =
       outer_declaration_scope ? outer_declaration_scope->is_being_lazily_parsed_
                               : false;
 #endif
 }
@@ skipping 364 matching lines @@
 void DeclarationScope::DeclareDefaultFunctionVariables(
     AstValueFactory* ast_value_factory) {
   DCHECK(is_function_scope());
   DCHECK(!is_arrow_scope());
 
   DeclareThis(ast_value_factory);
   new_target_ = Declare(zone(), ast_value_factory->new_target_string(), CONST);
 
   if (IsConciseMethod(function_kind_) || IsClassConstructor(function_kind_) ||
       IsAccessorFunction(function_kind_)) {
-    this_function_ =
+    EnsureRareData()->this_function =
         Declare(zone(), ast_value_factory->this_function_string(), CONST);
   }
 }
 
 Variable* DeclarationScope::DeclareFunctionVar(const AstRawString* name) {
   DCHECK(is_function_scope());
   DCHECK_NULL(function_);
   DCHECK_NULL(variables_.Lookup(name));
   VariableKind kind = is_sloppy(language_mode()) ? SLOPPY_FUNCTION_NAME_VARIABLE
                                                  : NORMAL_VARIABLE;
   function_ =
       new (zone()) Variable(this, name, CONST, kind, kCreatedInitialized);
   if (calls_sloppy_eval()) {
     NonLocal(name, DYNAMIC);
   } else {
     variables_.Add(zone(), function_);
   }
   return function_;
 }
 
+Variable* DeclarationScope::DeclareGeneratorObjectVar(
+    const AstRawString* name) {
+  DCHECK(is_function_scope() || is_module_scope());
+  DCHECK_NULL(generator_object_var());
+
+  Variable* result = EnsureRareData()->generator_object = NewTemporary(name);
+  result->set_is_used();
+  return result;
+}
+
+Variable* DeclarationScope::DeclarePromiseVar(const AstRawString* name) {
+  DCHECK(is_function_scope());
+  DCHECK_NULL(promise_var());
+  Variable* result = EnsureRareData()->promise = NewTemporary(name);
+  result->set_is_used();
+  return result;
+}
+
 bool Scope::HasBeenRemoved() const {
   if (sibling() == this) {
     DCHECK_NULL(inner_scope_);
     DCHECK(is_block_scope());
     return true;
   }
   return false;
 }
 
 Scope* Scope::GetUnremovedScope() {
@@ skipping 1387 matching lines @@
     AllocateNonParameterLocal(function_);
   }
 
   DCHECK(!has_rest_ || !MustAllocate(rest_parameter()) ||
          !rest_parameter()->IsUnallocated());
 
   if (new_target_ != nullptr && !MustAllocate(new_target_)) {
     new_target_ = nullptr;
   }
 
-  if (this_function_ != nullptr && !MustAllocate(this_function_)) {
-    this_function_ = nullptr;
-  }
+  NullifyRareVariableIf(RareVariable::kThisFunction,
+                        [=](Variable* var) { return !MustAllocate(var); });
 }
 
 void ModuleScope::AllocateModuleVariables() {
   for (const auto& it : module()->regular_imports()) {
     Variable* var = LookupLocal(it.first);
     var->AllocateTo(VariableLocation::MODULE, it.second->cell_index);
     DCHECK(!var->IsExport());
   }
 
   for (const auto& it : module()->regular_exports()) {
@@ skipping 106 matching lines @@
   Variable* function =
       is_function_scope() ? AsDeclarationScope()->function_var() : nullptr;
   bool is_function_var_in_context =
       function != nullptr && function->IsContextSlot();
   return num_heap_slots() - Context::MIN_CONTEXT_SLOTS -
          (is_function_var_in_context ? 1 : 0);
 }
 
 }  // namespace internal
 }  // namespace v8