[offthread] Add off-thread class boilerplate allocation

Add off-thread support for class boilerplate allocation, removing a
previously "unreachable" overload. Notably, this requires support for
off-thread allocation of Dictionaries and DescriptorArrays. Due to
template fun, the off-thread allocation of Dictionaries in particular
requires some amount of boilerplate (no pun intended).

Bug: chromium:1011762
Change-Id: I37139d924858e31e45d369742329826784a8f614
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2080370
Commit-Queue: Igor Sheludko <ishell@chromium.org>
Auto-Submit: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Igor Sheludko <ishell@chromium.org>
Reviewed-by: Toon Verwaest <verwaest@chromium.org>
Cr-Commit-Position: refs/heads/master@{#66580}

src/execution/off-thread-isolate.h

@@ -14,7 +14,6 @@ namespace v8 {
 namespace internal {
 
 class Isolate;
-class OffThreadIsolate;
 class OffThreadLogger;
 
 // HiddenOffThreadFactory parallels Isolate's HiddenFactory

src/handles/handles-inl.h

@@ -196,6 +196,13 @@ inline SealHandleScope::~SealHandleScope() {
 
 #endif
 
+template <typename T>
+Handle<T> OffThreadHandleScope::CloseAndEscape(Handle<T> handle_value) {
+  // At the moment, off-thread handle scopes do nothing on close, so we can
+  // safely return the same handle value.
+  return handle_value;
+}
+
 }  // namespace internal
 }  // namespace v8
 

src/handles/handles.h

@@ -368,6 +368,9 @@ class OffThreadHandleScope {
   // Off-thread Handles are allocated in the parse/compile zone, and not
   // cleared out, so the scope doesn't have to do anything
   explicit OffThreadHandleScope(OffThreadIsolate* isolate) {}
+
+  template <typename T>
+  inline Handle<T> CloseAndEscape(Handle<T> handle_value);
 };
 
 }  // namespace internal

src/heap/factory-base.cc

@@ -55,6 +55,15 @@ Handle<Struct> FactoryBase<Impl>::NewStruct(InstanceType type,
   return str;
 }
 
+template <typename Impl>
+Handle<AccessorPair> FactoryBase<Impl>::NewAccessorPair() {
+  Handle<AccessorPair> accessors = Handle<AccessorPair>::cast(
+      NewStruct(ACCESSOR_PAIR_TYPE, AllocationType::kOld));
+  accessors->set_getter(read_only_roots().null_value(), SKIP_WRITE_BARRIER);
+  accessors->set_setter(read_only_roots().null_value(), SKIP_WRITE_BARRIER);
+  return accessors;
+}
+
 template <typename Impl>
 Handle<FixedArray> FactoryBase<Impl>::NewFixedArray(int length,
                                                     AllocationType allocation) {
@@ -637,6 +646,32 @@ Handle<SharedFunctionInfo> FactoryBase<Impl>::NewSharedFunctionInfo() {
   return shared;
 }
 
+template <typename Impl>
+Handle<DescriptorArray> FactoryBase<Impl>::NewDescriptorArray(
+    int number_of_descriptors, int slack, AllocationType allocation) {
+  int number_of_all_descriptors = number_of_descriptors + slack;
+  // Zero-length case must be handled outside.
+  DCHECK_LT(0, number_of_all_descriptors);
+  int size = DescriptorArray::SizeFor(number_of_all_descriptors);
+  HeapObject obj = AllocateRawWithImmortalMap(
+      size, AllocationType::kYoung, read_only_roots().descriptor_array_map());
+  DescriptorArray array = DescriptorArray::cast(obj);
+  array.Initialize(read_only_roots().empty_enum_cache(),
+                   read_only_roots().undefined_value(), number_of_descriptors,
+                   slack);
+  return handle(array, isolate());
+}
+
+template <typename Impl>
+Handle<ClassPositions> FactoryBase<Impl>::NewClassPositions(int start,
+                                                            int end) {
+  Handle<ClassPositions> class_positions = Handle<ClassPositions>::cast(
+      NewStruct(CLASS_POSITIONS_TYPE, AllocationType::kOld));
+  class_positions->set_start(start);
+  class_positions->set_end(end);
+  return class_positions;
+}
+
 template <typename Impl>
 Handle<SeqOneByteString>
 FactoryBase<Impl>::AllocateRawOneByteInternalizedString(int length,

src/heap/factory-base.h

@@ -29,6 +29,7 @@ class UncompiledDataWithoutPreparseData;
 class UncompiledDataWithPreparseData;
 class BytecodeArray;
 class CoverageInfo;
+class ClassPositions;
 struct SourceRange;
 template <typename T>
 class ZoneVector;
@@ -64,6 +65,9 @@ class EXPORT_TEMPLATE_DECLARE(V8_EXPORT_PRIVATE) FactoryBase {
   Handle<Struct> NewStruct(InstanceType type,
                            AllocationType allocation = AllocationType::kYoung);
 
+  // Create a pre-tenured empty AccessorPair.
+  Handle<AccessorPair> NewAccessorPair();
+
   // Allocates a fixed array initialized with undefined values.
   Handle<FixedArray> NewFixedArray(
       int length, AllocationType allocation = AllocationType::kYoung);
@@ -175,6 +179,12 @@ class EXPORT_TEMPLATE_DECLARE(V8_EXPORT_PRIVATE) FactoryBase {
 
   Handle<SourceTextModuleInfo> NewSourceTextModuleInfo();
 
+  Handle<DescriptorArray> NewDescriptorArray(
+      int number_of_entries, int slack = 0,
+      AllocationType allocation = AllocationType::kYoung);
+
+  Handle<ClassPositions> NewClassPositions(int start, int end);
+
  protected:
   // Allocate memory for an uninitialized array (e.g., a FixedArray or similar).
   HeapObject AllocateRawArray(int size, AllocationType allocation);

src/heap/factory.cc

@@ -501,14 +501,6 @@ Handle<OrderedNameDictionary> Factory::NewOrderedNameDictionary() {
       .ToHandleChecked();
 }
 
-Handle<AccessorPair> Factory::NewAccessorPair() {
-  Handle<AccessorPair> accessors = Handle<AccessorPair>::cast(
-      NewStruct(ACCESSOR_PAIR_TYPE, AllocationType::kOld));
-  accessors->set_getter(*null_value(), SKIP_WRITE_BARRIER);
-  accessors->set_setter(*null_value(), SKIP_WRITE_BARRIER);
-  return accessors;
-}
-
 Handle<PropertyDescriptorObject> Factory::NewPropertyDescriptorObject() {
   Handle<PropertyDescriptorObject> object =
       Handle<PropertyDescriptorObject>::cast(
@@ -1361,21 +1353,6 @@ Handle<PropertyCell> Factory::NewPropertyCell(Handle<Name> name,
   return cell;
 }
 
-Handle<DescriptorArray> Factory::NewDescriptorArray(int number_of_descriptors,
-                                                    int slack) {
-  int number_of_all_descriptors = number_of_descriptors + slack;
-  // Zero-length case must be handled outside.
-  DCHECK_LT(0, number_of_all_descriptors);
-  int size = DescriptorArray::SizeFor(number_of_all_descriptors);
-  HeapObject obj = isolate()->heap()->AllocateRawWith<Heap::kRetryOrFail>(
-      size, AllocationType::kYoung);
-  obj.set_map_after_allocation(*descriptor_array_map(), SKIP_WRITE_BARRIER);
-  DescriptorArray array = DescriptorArray::cast(obj);
-  array.Initialize(*empty_enum_cache(), *undefined_value(),
-                   number_of_descriptors, slack);
-  return Handle<DescriptorArray>(array, isolate());
-}
-
 Handle<TransitionArray> Factory::NewTransitionArray(int number_of_transitions,
                                                     int slack) {
   int capacity = TransitionArray::LengthFor(number_of_transitions + slack);
@@ -3019,14 +2996,6 @@ Handle<String> Factory::SizeToString(size_t value, bool check_cache) {
   return result;
 }
 
-Handle<ClassPositions> Factory::NewClassPositions(int start, int end) {
-  Handle<ClassPositions> class_positions = Handle<ClassPositions>::cast(
-      NewStruct(CLASS_POSITIONS_TYPE, AllocationType::kOld));
-  class_positions->set_start(start);
-  class_positions->set_end(end);
-  return class_positions;
-}
-
 Handle<DebugInfo> Factory::NewDebugInfo(Handle<SharedFunctionInfo> shared) {
   DCHECK(!shared->HasDebugInfo());
   Heap* heap = isolate()->heap();

src/heap/factory.h

@@ -167,9 +167,6 @@ class V8_EXPORT_PRIVATE Factory : public FactoryBase<Factory> {
   Handle<Tuple2> NewTuple2(Handle<Object> value1, Handle<Object> value2,
                            AllocationType allocation);
 
-  // Create a pre-tenured empty AccessorPair.
-  Handle<AccessorPair> NewAccessorPair();
-
   // Create a new PropertyDescriptorObject struct.
   Handle<PropertyDescriptorObject> NewPropertyDescriptorObject();
 
@@ -381,8 +378,6 @@ class V8_EXPORT_PRIVATE Factory : public FactoryBase<Factory> {
   Handle<FeedbackCell> NewOneClosureCell(Handle<HeapObject> value);
   Handle<FeedbackCell> NewManyClosuresCell(Handle<HeapObject> value);
 
-  Handle<DescriptorArray> NewDescriptorArray(int number_of_entries,
-                                             int slack = 0);
   Handle<TransitionArray> NewTransitionArray(int number_of_transitions,
                                              int slack = 0);
 
@@ -730,7 +725,6 @@ class V8_EXPORT_PRIVATE Factory : public FactoryBase<Factory> {
       int end_position, Handle<SharedFunctionInfo> shared_info,
       int bytecode_offset, Handle<Script> script, Handle<Object> stack_frames);
 
-  Handle<ClassPositions> NewClassPositions(int start, int end);
   Handle<DebugInfo> NewDebugInfo(Handle<SharedFunctionInfo> shared);
 
   // Return a map for given number of properties using the map cache in the

src/objects/descriptor-array.h

@@ -5,6 +5,7 @@
 #ifndef V8_OBJECTS_DESCRIPTOR_ARRAY_H_
 #define V8_OBJECTS_DESCRIPTOR_ARRAY_H_
 
+#include "src/common/globals.h"
 #include "src/objects/fixed-array.h"
 // TODO(jkummerow): Consider forward-declaring instead.
 #include "src/base/bit-field.h"
@@ -126,9 +127,10 @@ class DescriptorArray : public HeapObject {
 
   // Allocates a DescriptorArray, but returns the singleton
   // empty descriptor array object if number_of_descriptors is 0.
-  V8_EXPORT_PRIVATE static Handle<DescriptorArray> Allocate(Isolate* isolate,
-                                                            int nof_descriptors,
-                                                            int slack);
+  template <typename LocalIsolate>
+  V8_EXPORT_PRIVATE static Handle<DescriptorArray> Allocate(
+      LocalIsolate* isolate, int nof_descriptors, int slack,
+      AllocationType allocation = AllocationType::kYoung);
 
   void Initialize(EnumCache enum_cache, HeapObject undefined_value,
                   int nof_descriptors, int slack);

src/objects/dictionary-inl.h

@@ -264,6 +264,11 @@ Handle<Object> NumberDictionaryBaseShape::AsHandle(Isolate* isolate,
   return isolate->factory()->NewNumberFromUint(key);
 }
 
+Handle<Object> NumberDictionaryBaseShape::AsHandle(OffThreadIsolate* isolate,
+                                                   uint32_t key) {
+  return isolate->factory()->NewNumberFromUint<AllocationType::kOld>(key);
+}
+
 Handle<Map> NumberDictionaryShape::GetMap(ReadOnlyRoots roots) {
   return roots.number_dictionary_map_handle();
 }
@@ -302,6 +307,12 @@ Handle<Object> NameDictionaryShape::AsHandle(Isolate* isolate,
   return key;
 }
 
+Handle<Object> NameDictionaryShape::AsHandle(OffThreadIsolate* isolate,
+                                             Handle<Name> key) {
+  DCHECK(key->IsUniqueName());
+  return key;
+}
+
 template <typename Dictionary>
 PropertyDetails GlobalDictionaryShape::DetailsAt(Dictionary dict,
                                                  InternalIndex entry) {

src/objects/dictionary.h

@@ -72,8 +72,9 @@ class EXPORT_TEMPLATE_DECLARE(V8_EXPORT_PRIVATE) Dictionary
   // Garbage collection support.
   inline ObjectSlot RawFieldOfValueAt(InternalIndex entry);
 
+  template <typename LocalIsolate>
   V8_WARN_UNUSED_RESULT static Handle<Derived> Add(
-      Isolate* isolate, Handle<Derived> dictionary, Key key,
+      LocalIsolate* isolate, Handle<Derived> dictionary, Key key,
       Handle<Object> value, PropertyDetails details,
       InternalIndex* entry_out = nullptr);
 
@@ -111,6 +112,8 @@ class NameDictionaryShape : public BaseDictionaryShape<Handle<Name>> {
   static inline uint32_t Hash(ReadOnlyRoots roots, Handle<Name> key);
   static inline uint32_t HashForObject(ReadOnlyRoots roots, Object object);
   static inline Handle<Object> AsHandle(Isolate* isolate, Handle<Name> key);
+  static inline Handle<Object> AsHandle(OffThreadIsolate* isolate,
+                                        Handle<Name> key);
   static inline Handle<Map> GetMap(ReadOnlyRoots roots);
   static const int kPrefixSize = 2;
   static const int kEntrySize = 3;
@@ -133,8 +136,9 @@ class EXPORT_TEMPLATE_DECLARE(V8_EXPORT_PRIVATE) BaseNameDictionary
   inline int Hash() const;
 
   // Creates a new dictionary.
+  template <typename LocalIsolate>
   V8_WARN_UNUSED_RESULT static Handle<Derived> New(
-      Isolate* isolate, int at_least_space_for,
+      LocalIsolate* isolate, int at_least_space_for,
       AllocationType allocation = AllocationType::kYoung,
       MinimumCapacity capacity_option = USE_DEFAULT_MINIMUM_CAPACITY);
 
@@ -161,8 +165,9 @@ class EXPORT_TEMPLATE_DECLARE(V8_EXPORT_PRIVATE) BaseNameDictionary
                              Handle<FixedArray> storage, KeyCollectionMode mode,
                              KeyAccumulator* accumulator);
 
+  template <typename LocalIsolate>
   V8_WARN_UNUSED_RESULT static Handle<Derived> AddNoUpdateNextEnumerationIndex(
-      Isolate* isolate, Handle<Derived> dictionary, Key key,
+      LocalIsolate* isolate, Handle<Derived> dictionary, Key key,
       Handle<Object> value, PropertyDetails details,
       InternalIndex* entry_out = nullptr);
 
@@ -246,6 +251,8 @@ class NumberDictionaryBaseShape : public BaseDictionaryShape<uint32_t> {
  public:
   static inline bool IsMatch(uint32_t key, Object other);
   static inline Handle<Object> AsHandle(Isolate* isolate, uint32_t key);
+  static inline Handle<Object> AsHandle(OffThreadIsolate* isolate,
+                                        uint32_t key);
 
   static inline uint32_t Hash(ReadOnlyRoots roots, uint32_t key);
   static inline uint32_t HashForObject(ReadOnlyRoots roots, Object object);

src/objects/elements.cc

@@ -2723,14 +2723,12 @@ class FastSealedObjectElementsAccessor
 class FastPackedSealedObjectElementsAccessor
     : public FastSealedObjectElementsAccessor<
           FastPackedSealedObjectElementsAccessor,
-          ElementsKindTraits<PACKED_SEALED_ELEMENTS>> {
-};
+          ElementsKindTraits<PACKED_SEALED_ELEMENTS>> {};
 
 class FastHoleySealedObjectElementsAccessor
     : public FastSealedObjectElementsAccessor<
           FastHoleySealedObjectElementsAccessor,
-          ElementsKindTraits<HOLEY_SEALED_ELEMENTS>> {
-};
+          ElementsKindTraits<HOLEY_SEALED_ELEMENTS>> {};
 
 template <typename Subclass, typename KindTraits>
 class FastFrozenObjectElementsAccessor
@@ -2802,14 +2800,12 @@ class FastFrozenObjectElementsAccessor
 class FastPackedFrozenObjectElementsAccessor
     : public FastFrozenObjectElementsAccessor<
           FastPackedFrozenObjectElementsAccessor,
-          ElementsKindTraits<PACKED_FROZEN_ELEMENTS>> {
-};
+          ElementsKindTraits<PACKED_FROZEN_ELEMENTS>> {};
 
 class FastHoleyFrozenObjectElementsAccessor
     : public FastFrozenObjectElementsAccessor<
           FastHoleyFrozenObjectElementsAccessor,
-          ElementsKindTraits<HOLEY_FROZEN_ELEMENTS>> {
-};
+          ElementsKindTraits<HOLEY_FROZEN_ELEMENTS>> {};
 
 class FastHoleyObjectElementsAccessor
     : public FastSmiOrObjectElementsAccessor<

src/objects/hash-table.h

@@ -129,8 +129,9 @@ class EXPORT_TEMPLATE_DECLARE(V8_EXPORT_PRIVATE) HashTable
   using Key = typename Shape::Key;
 
   // Returns a new HashTable object.
+  template <typename LocalIsolate>
   V8_WARN_UNUSED_RESULT static Handle<Derived> New(
-      Isolate* isolate, int at_least_space_for,
+      LocalIsolate* isolate, int at_least_space_for,
       AllocationType allocation = AllocationType::kYoung,
       MinimumCapacity capacity_option = USE_DEFAULT_MINIMUM_CAPACITY);
 
@@ -192,8 +193,9 @@ class EXPORT_TEMPLATE_DECLARE(V8_EXPORT_PRIVATE) HashTable
   }
 
   // Ensure enough space for n additional elements.
+  template <typename LocalIsolate>
   V8_WARN_UNUSED_RESULT static Handle<Derived> EnsureCapacity(
-      Isolate* isolate, Handle<Derived> table, int n = 1,
+      LocalIsolate* isolate, Handle<Derived> table, int n = 1,
       AllocationType allocation = AllocationType::kYoung);
 
   // Returns true if this table has sufficient capacity for adding n elements.
@@ -202,8 +204,9 @@ class EXPORT_TEMPLATE_DECLARE(V8_EXPORT_PRIVATE) HashTable
  protected:
   friend class ObjectHashTable;
 
+  template <typename LocalIsolate>
   V8_WARN_UNUSED_RESULT static Handle<Derived> NewInternal(
-      Isolate* isolate, int capacity, AllocationType allocation);
+      LocalIsolate* isolate, int capacity, AllocationType allocation);
 
   // Find the entry at which to insert element with the given key that
   // has the given hash value.
@@ -244,9 +247,23 @@ class EXPORT_TEMPLATE_DECLARE(V8_EXPORT_PRIVATE) HashTable
   OBJECT_CONSTRUCTORS(HashTable, HashTableBase);
 };
 
-#define EXTERN_DECLARE_HASH_TABLE(DERIVED, SHAPE)                  \
-  extern template class EXPORT_TEMPLATE_DECLARE(V8_EXPORT_PRIVATE) \
-      HashTable<class DERIVED, SHAPE>;
+#define EXTERN_DECLARE_HASH_TABLE(DERIVED, SHAPE)                            \
+  extern template class EXPORT_TEMPLATE_DECLARE(V8_EXPORT_PRIVATE)           \
+      HashTable<class DERIVED, SHAPE>;                                       \
+                                                                             \
+  extern template EXPORT_TEMPLATE_DECLARE(V8_EXPORT_PRIVATE) Handle<DERIVED> \
+  HashTable<DERIVED, SHAPE>::New(Isolate*, int, AllocationType,              \
+                                 MinimumCapacity);                           \
+  extern template EXPORT_TEMPLATE_DECLARE(V8_EXPORT_PRIVATE) Handle<DERIVED> \
+  HashTable<DERIVED, SHAPE>::New(OffThreadIsolate*, int, AllocationType,     \
+                                 MinimumCapacity);                           \
+                                                                             \
+  extern template EXPORT_TEMPLATE_DECLARE(V8_EXPORT_PRIVATE) Handle<DERIVED> \
+  HashTable<DERIVED, SHAPE>::EnsureCapacity(Isolate*, Handle<DERIVED>, int,  \
+                                            AllocationType);                 \
+  extern template EXPORT_TEMPLATE_DECLARE(V8_EXPORT_PRIVATE) Handle<DERIVED> \
+  HashTable<DERIVED, SHAPE>::EnsureCapacity(                                 \
+      OffThreadIsolate*, Handle<DERIVED>, int, AllocationType);
 
 // HashTableKey is an abstract superclass for virtual key behavior.
 class HashTableKey {

src/objects/literal-objects.cc

@@ -7,8 +7,11 @@
 #include "src/ast/ast.h"
 #include "src/base/logging.h"
 #include "src/builtins/accessors.h"
+#include "src/common/globals.h"
 #include "src/execution/isolate.h"
 #include "src/heap/factory.h"
+#include "src/heap/off-thread-factory-inl.h"
+#include "src/objects/dictionary.h"
 #include "src/objects/hash-table-inl.h"
 #include "src/objects/literal-objects-inl.h"
 #include "src/objects/objects-inl.h"
@@ -28,8 +31,9 @@ inline int EncodeComputedEntry(ClassBoilerplate::ValueKind value_kind,
   return flags;
 }
 
+template <typename LocalIsolate>
 void AddToDescriptorArrayTemplate(
-    Isolate* isolate, Handle<DescriptorArray> descriptor_array_template,
+    LocalIsolate* isolate, Handle<DescriptorArray> descriptor_array_template,
     Handle<Name> name, ClassBoilerplate::ValueKind value_kind,
     Handle<Object> value) {
   InternalIndex entry = descriptor_array_template->Search(
@@ -80,17 +84,19 @@ void AddToDescriptorArrayTemplate(
   }
 }
 
+template <typename LocalIsolate>
 Handle<NameDictionary> DictionaryAddNoUpdateNextEnumerationIndex(
-    Isolate* isolate, Handle<NameDictionary> dictionary, Handle<Name> name,
+    LocalIsolate* isolate, Handle<NameDictionary> dictionary, Handle<Name> name,
     Handle<Object> value, PropertyDetails details,
     InternalIndex* entry_out = nullptr) {
   return NameDictionary::AddNoUpdateNextEnumerationIndex(
       isolate, dictionary, name, value, details, entry_out);
 }
 
+template <typename LocalIsolate>
 Handle<NumberDictionary> DictionaryAddNoUpdateNextEnumerationIndex(
-    Isolate* isolate, Handle<NumberDictionary> dictionary, uint32_t element,
-    Handle<Object> value, PropertyDetails details,
+    LocalIsolate* isolate, Handle<NumberDictionary> dictionary,
+    uint32_t element, Handle<Object> value, PropertyDetails details,
     InternalIndex* entry_out = nullptr) {
   // NumberDictionary does not maintain the enumeration order, so it's
   // a normal Add().
@@ -121,9 +127,10 @@ inline int GetExistingValueIndex(Object value) {
   return value.IsSmi() ? Smi::ToInt(value) : -1;
 }
 
-template <typename Dictionary, typename Key>
-void AddToDictionaryTemplate(Isolate* isolate, Handle<Dictionary> dictionary,
-                             Key key, int key_index,
+template <typename LocalIsolate, typename Dictionary, typename Key>
+void AddToDictionaryTemplate(LocalIsolate* isolate,
+                             Handle<Dictionary> dictionary, Key key,
+                             int key_index,
                              ClassBoilerplate::ValueKind value_kind,
                              Smi value) {
   InternalIndex entry = dictionary->FindEntry(ReadOnlyRoots(isolate), key);
@@ -253,6 +260,7 @@ void AddToDictionaryTemplate(Isolate* isolate, Handle<Dictionary> dictionary,
 
 // Helper class that eases building of a properties, elements and computed
 // properties templates.
+template <typename LocalIsolate>
 class ObjectDescriptor {
  public:
   void IncComputedCount() { ++computed_count_; }
@@ -281,14 +289,16 @@ class ObjectDescriptor {
     return computed_properties_;
   }
 
-  void CreateTemplates(Isolate* isolate) {
-    Factory* factory = isolate->factory();
+  void CreateTemplates(LocalIsolate* isolate) {
+    auto* factory = isolate->factory();
     descriptor_array_template_ = factory->empty_descriptor_array();
-    properties_dictionary_template_ = factory->empty_property_dictionary();
+    properties_dictionary_template_ =
+        Handle<NameDictionary>::cast(factory->empty_property_dictionary());
     if (property_count_ || computed_count_ || property_slack_) {
       if (HasDictionaryProperties()) {
         properties_dictionary_template_ = NameDictionary::New(
-            isolate, property_count_ + computed_count_ + property_slack_);
+            isolate, property_count_ + computed_count_ + property_slack_,
+            AllocationType::kOld);
       } else {
         descriptor_array_template_ = DescriptorArray::Allocate(
             isolate, 0, property_count_ + property_slack_);
@@ -306,8 +316,8 @@ class ObjectDescriptor {
     temp_handle_ = handle(Smi::zero(), isolate);
   }
 
-  void AddConstant(Isolate* isolate, Handle<Name> name, Handle<Object> value,
-                   PropertyAttributes attribs) {
+  void AddConstant(LocalIsolate* isolate, Handle<Name> name,
+                   Handle<Object> value, PropertyAttributes attribs) {
     bool is_accessor = value->IsAccessorInfo();
     DCHECK(!value->IsAccessorPair());
     if (HasDictionaryProperties()) {
@@ -325,7 +335,7 @@ class ObjectDescriptor {
     }
   }
 
-  void AddNamedProperty(Isolate* isolate, Handle<Name> name,
+  void AddNamedProperty(LocalIsolate* isolate, Handle<Name> name,
                         ClassBoilerplate::ValueKind value_kind,
                         int value_index) {
     Smi value = Smi::FromInt(value_index);
@@ -340,7 +350,7 @@ class ObjectDescriptor {
     }
   }
 
-  void AddIndexedProperty(Isolate* isolate, uint32_t element,
+  void AddIndexedProperty(LocalIsolate* isolate, uint32_t element,
                           ClassBoilerplate::ValueKind value_kind,
                           int value_index) {
     Smi value = Smi::FromInt(value_index);
@@ -362,7 +372,7 @@ class ObjectDescriptor {
     next_enumeration_index_ = next_index;
   }
 
-  void Finalize(Isolate* isolate) {
+  void Finalize(LocalIsolate* isolate) {
     if (HasDictionaryProperties()) {
       DCHECK_EQ(current_computed_index_, computed_properties_->length());
       properties_dictionary_template_->set_next_enumeration_index(
@@ -388,33 +398,51 @@ class ObjectDescriptor {
   Handle<Object> temp_handle_;
 };
 
+template <typename LocalIsolate>
 void ClassBoilerplate::AddToPropertiesTemplate(
-    Isolate* isolate, Handle<NameDictionary> dictionary, Handle<Name> name,
+    LocalIsolate* isolate, Handle<NameDictionary> dictionary, Handle<Name> name,
     int key_index, ClassBoilerplate::ValueKind value_kind, Smi value) {
   AddToDictionaryTemplate(isolate, dictionary, name, key_index, value_kind,
                           value);
 }
+template void ClassBoilerplate::AddToPropertiesTemplate(
+    Isolate* isolate, Handle<NameDictionary> dictionary, Handle<Name> name,
+    int key_index, ClassBoilerplate::ValueKind value_kind, Smi value);
+template void ClassBoilerplate::AddToPropertiesTemplate(
+    OffThreadIsolate* isolate, Handle<NameDictionary> dictionary,
+    Handle<Name> name, int key_index, ClassBoilerplate::ValueKind value_kind,
+    Smi value);
 
+template <typename LocalIsolate>
 void ClassBoilerplate::AddToElementsTemplate(
-    Isolate* isolate, Handle<NumberDictionary> dictionary, uint32_t key,
+    LocalIsolate* isolate, Handle<NumberDictionary> dictionary, uint32_t key,
     int key_index, ClassBoilerplate::ValueKind value_kind, Smi value) {
   AddToDictionaryTemplate(isolate, dictionary, key, key_index, value_kind,
                           value);
 }
+template void ClassBoilerplate::AddToElementsTemplate(
+    Isolate* isolate, Handle<NumberDictionary> dictionary, uint32_t key,
+    int key_index, ClassBoilerplate::ValueKind value_kind, Smi value);
+template void ClassBoilerplate::AddToElementsTemplate(
+    OffThreadIsolate* isolate, Handle<NumberDictionary> dictionary,
+    uint32_t key, int key_index, ClassBoilerplate::ValueKind value_kind,
+    Smi value);
 
+template <typename LocalIsolate>
 Handle<ClassBoilerplate> ClassBoilerplate::BuildClassBoilerplate(
-    Isolate* isolate, ClassLiteral* expr) {
+    LocalIsolate* isolate, ClassLiteral* expr) {
   // Create a non-caching handle scope to ensure that the temporary handle used
   // by ObjectDescriptor for passing Smis around does not corrupt handle cache
   // in CanonicalHandleScope.
-  HandleScope scope(isolate);
-  Factory* factory = isolate->factory();
-  ObjectDescriptor static_desc(kMinimumClassPropertiesCount);
-  ObjectDescriptor instance_desc(kMinimumPrototypePropertiesCount);
+  typename LocalIsolate::HandleScopeType scope(isolate);
+  auto* factory = isolate->factory();
+  ObjectDescriptor<LocalIsolate> static_desc(kMinimumClassPropertiesCount);
+  ObjectDescriptor<LocalIsolate> instance_desc(
+      kMinimumPrototypePropertiesCount);
 
   for (int i = 0; i < expr->public_members()->length(); i++) {
     ClassLiteral::Property* property = expr->public_members()->at(i);
-    ObjectDescriptor& desc =
+    ObjectDescriptor<LocalIsolate>& desc =
         property->is_static() ? static_desc : instance_desc;
     if (property->is_computed_name()) {
       if (property->kind() != ClassLiteral::Property::FIELD) {
@@ -500,7 +528,7 @@ Handle<ClassBoilerplate> ClassBoilerplate::BuildClassBoilerplate(
         continue;
     }
 
-    ObjectDescriptor& desc =
+    ObjectDescriptor<LocalIsolate>& desc =
         property->is_static() ? static_desc : instance_desc;
     if (property->is_computed_name()) {
       int computed_name_index = dynamic_argument_index;
@@ -567,11 +595,10 @@ Handle<ClassBoilerplate> ClassBoilerplate::BuildClassBoilerplate(
   return scope.CloseAndEscape(class_boilerplate);
 }
 
-Handle<ClassBoilerplate> ClassBoilerplate::BuildClassBoilerplate(
-    OffThreadIsolate* isolate, ClassLiteral* expr) {
-  // TODO(leszeks): Add class boilerplate support to off-thread finalization.
-  UNREACHABLE();
-}
+template Handle<ClassBoilerplate> ClassBoilerplate::BuildClassBoilerplate(
+    Isolate* isolate, ClassLiteral* expr);
+template Handle<ClassBoilerplate> ClassBoilerplate::BuildClassBoilerplate(
+    OffThreadIsolate* isolate, ClassLiteral* expr);
 
 }  // namespace internal
 }  // namespace v8

src/objects/literal-objects.h

@@ -117,22 +117,22 @@ class ClassBoilerplate : public FixedArray {
   DECL_ACCESSORS(instance_elements_template, Object)
   DECL_ACCESSORS(instance_computed_properties, FixedArray)
 
-  static void AddToPropertiesTemplate(Isolate* isolate,
+  template <typename LocalIsolate>
+  static void AddToPropertiesTemplate(LocalIsolate* isolate,
                                       Handle<NameDictionary> dictionary,
                                       Handle<Name> name, int key_index,
                                       ValueKind value_kind, Smi value);
 
-  static void AddToElementsTemplate(Isolate* isolate,
+  template <typename LocalIsolate>
+  static void AddToElementsTemplate(LocalIsolate* isolate,
                                     Handle<NumberDictionary> dictionary,
                                     uint32_t key, int key_index,
                                     ValueKind value_kind, Smi value);
 
-  static Handle<ClassBoilerplate> BuildClassBoilerplate(Isolate* isolate,
+  template <typename LocalIsolate>
+  static Handle<ClassBoilerplate> BuildClassBoilerplate(LocalIsolate* isolate,
                                                         ClassLiteral* expr);
 
-  static Handle<ClassBoilerplate> BuildClassBoilerplate(
-      OffThreadIsolate* isolate, ClassLiteral* expr);
-
   enum {
     kFlagsIndex,
     kClassPropertiesTemplateIndex,