[compiler] Replace ScopeInfoData with direct reads

As part of this, introduce a new ObjectData kind for objects that we
want to read directly from the background thread rather than serialize.
ScopeInfoRef is the first user of that.

For details, see:
https://docs.google.com/document/d/1U6x6Q2bpylfxS55nxSe17yyBW0bQG-ycoBhVA82VmS0/edit?usp=sharing

Bug: v8:7790
Change-Id: Ia3cda4f67d3922367afa4a5da2aeaae7160cf1f2
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2346405
Auto-Submit: Georg Neis <neis@chromium.org>
Commit-Queue: Georg Neis <neis@chromium.org>
Reviewed-by: Nico Hartmann <nicohartmann@chromium.org>
Reviewed-by: Santiago Aboy Solanes <solanes@chromium.org>
Cr-Commit-Position: refs/heads/master@{#69473}

src/ast/scopes.h

@@ -705,8 +705,6 @@ class V8_EXPORT_PRIVATE Scope : public NON_EXPORTED_BASE(ZoneObject) {
 
   void SetDefaults();
 
-  void set_scope_info(Handle<ScopeInfo> scope_info);
-
   friend class DeclarationScope;
   friend class ClassScope;
   friend class ScopeTestHelper;

src/codegen/compiler.cc

@@ -596,7 +596,7 @@ void UpdateSharedFunctionFlagsAfterCompilation(FunctionLiteral* literal,
   shared_info.set_has_static_private_methods_or_accessors(
       literal->has_static_private_methods_or_accessors());
 
-  shared_info.set_scope_info(*literal->scope()->scope_info());
+  shared_info.SetScopeInfo(*literal->scope()->scope_info());
 }
 
 // Finalize a single compilation job. This function can return

src/compiler/bytecode-graph-builder.cc

@@ -1785,7 +1785,7 @@ BytecodeGraphBuilder::Environment* BytecodeGraphBuilder::CheckContextExtensions(
   // in the same scope as the variable itself has no way of shadowing it.
   Environment* slow_environment = nullptr;
   for (uint32_t d = 0; d < depth; d++) {
-    if (scope_info.HasContextExtension()) {
+    if (scope_info.HasContextExtensionSlot()) {
       slow_environment = CheckContextExtensionAtDepth(slow_environment, d);
     }
     DCHECK_IMPLIES(!scope_info.HasOuterScopeInfo(), d + 1 == depth);

src/compiler/heap-refs.h

@@ -49,57 +49,58 @@ enum class OddballType : uint8_t {
 
 // This list is sorted such that subtypes appear before their supertypes.
 // DO NOT VIOLATE THIS PROPERTY!
-#define HEAP_BROKER_OBJECT_LIST(V) \
-  /* Subtypes of JSObject */       \
-  V(JSArray)                       \
-  V(JSBoundFunction)               \
-  V(JSDataView)                    \
-  V(JSFunction)                    \
-  V(JSGlobalObject)                \
-  V(JSGlobalProxy)                 \
-  V(JSRegExp)                      \
-  V(JSTypedArray)                  \
-  /* Subtypes of Context */        \
-  V(NativeContext)                 \
-  /* Subtypes of FixedArray */     \
-  V(Context)                       \
-  V(ObjectBoilerplateDescription)  \
-  V(ScopeInfo)                     \
-  V(ScriptContextTable)            \
-  /* Subtypes of FixedArrayBase */ \
-  V(BytecodeArray)                 \
-  V(FixedArray)                    \
-  V(FixedDoubleArray)              \
-  /* Subtypes of Name */           \
-  V(InternalizedString)            \
-  V(String)                        \
-  V(Symbol)                        \
-  /* Subtypes of JSReceiver */     \
-  V(JSObject)                      \
-  /* Subtypes of HeapObject */     \
-  V(AccessorInfo)                  \
-  V(AllocationSite)                \
-  V(ArrayBoilerplateDescription)   \
-  V(BigInt)                        \
-  V(CallHandlerInfo)               \
-  V(Cell)                          \
-  V(Code)                          \
-  V(DescriptorArray)               \
-  V(FeedbackCell)                  \
-  V(FeedbackVector)                \
-  V(FixedArrayBase)                \
-  V(FunctionTemplateInfo)          \
-  V(HeapNumber)                    \
-  V(JSReceiver)                    \
-  V(Map)                           \
-  V(Name)                          \
-  V(PropertyCell)                  \
-  V(SharedFunctionInfo)            \
-  V(SourceTextModule)              \
-  V(TemplateObjectDescription)     \
-  /* Subtypes of Object */         \
+#define HEAP_BROKER_SERIALIZED_OBJECT_LIST(V) \
+  /* Subtypes of JSObject */                  \
+  V(JSArray)                                  \
+  V(JSBoundFunction)                          \
+  V(JSDataView)                               \
+  V(JSFunction)                               \
+  V(JSGlobalObject)                           \
+  V(JSGlobalProxy)                            \
+  V(JSRegExp)                                 \
+  V(JSTypedArray)                             \
+  /* Subtypes of Context */                   \
+  V(NativeContext)                            \
+  /* Subtypes of FixedArray */                \
+  V(Context)                                  \
+  V(ObjectBoilerplateDescription)             \
+  V(ScriptContextTable)                       \
+  /* Subtypes of FixedArrayBase */            \
+  V(BytecodeArray)                            \
+  V(FixedArray)                               \
+  V(FixedDoubleArray)                         \
+  /* Subtypes of Name */                      \
+  V(InternalizedString)                       \
+  V(String)                                   \
+  V(Symbol)                                   \
+  /* Subtypes of JSReceiver */                \
+  V(JSObject)                                 \
+  /* Subtypes of HeapObject */                \
+  V(AccessorInfo)                             \
+  V(AllocationSite)                           \
+  V(ArrayBoilerplateDescription)              \
+  V(BigInt)                                   \
+  V(CallHandlerInfo)                          \
+  V(Cell)                                     \
+  V(Code)                                     \
+  V(DescriptorArray)                          \
+  V(FeedbackCell)                             \
+  V(FeedbackVector)                           \
+  V(FixedArrayBase)                           \
+  V(FunctionTemplateInfo)                     \
+  V(HeapNumber)                               \
+  V(JSReceiver)                               \
+  V(Map)                                      \
+  V(Name)                                     \
+  V(PropertyCell)                             \
+  V(SharedFunctionInfo)                       \
+  V(SourceTextModule)                         \
+  V(TemplateObjectDescription)                \
+  /* Subtypes of Object */                    \
   V(HeapObject)
 
+#define HEAP_BROKER_NEVER_SERIALIZED_OBJECT_LIST(V) V(ScopeInfo)
+
 class CompilationDependencies;
 struct FeedbackSource;
 class JSHeapBroker;
@@ -107,7 +108,8 @@ class ObjectData;
 class PerIsolateCompilerCache;
 class PropertyAccessInfo;
 #define FORWARD_DECL(Name) class Name##Ref;
-HEAP_BROKER_OBJECT_LIST(FORWARD_DECL)
+HEAP_BROKER_SERIALIZED_OBJECT_LIST(FORWARD_DECL)
+HEAP_BROKER_NEVER_SERIALIZED_OBJECT_LIST(FORWARD_DECL)
 #undef FORWARD_DECL
 
 class V8_EXPORT_PRIVATE ObjectRef {
@@ -127,11 +129,13 @@ class V8_EXPORT_PRIVATE ObjectRef {
   int AsSmi() const;
 
 #define HEAP_IS_METHOD_DECL(Name) bool Is##Name() const;
-  HEAP_BROKER_OBJECT_LIST(HEAP_IS_METHOD_DECL)
+  HEAP_BROKER_SERIALIZED_OBJECT_LIST(HEAP_IS_METHOD_DECL)
+  HEAP_BROKER_NEVER_SERIALIZED_OBJECT_LIST(HEAP_IS_METHOD_DECL)
 #undef HEAP_IS_METHOD_DECL
 
 #define HEAP_AS_METHOD_DECL(Name) Name##Ref As##Name() const;
-  HEAP_BROKER_OBJECT_LIST(HEAP_AS_METHOD_DECL)
+  HEAP_BROKER_SERIALIZED_OBJECT_LIST(HEAP_AS_METHOD_DECL)
+  HEAP_BROKER_NEVER_SERIALIZED_OBJECT_LIST(HEAP_AS_METHOD_DECL)
 #undef HEAP_AS_METHOD_DECL
 
   bool IsNullOrUndefined() const;
@@ -760,8 +764,7 @@ class ScopeInfoRef : public HeapObjectRef {
 
   int ContextLength() const;
   bool HasOuterScopeInfo() const;
-  int Flags() const;
-  bool HasContextExtension() const;
+  bool HasContextExtensionSlot() const;
 
   // Only serialized via SerializeScopeInfoChain.
   ScopeInfoRef OuterScopeInfo() const;

src/compiler/js-heap-broker.cc

@@ -45,7 +45,7 @@ namespace compiler {
 #define TRACE_MISSING(broker, x) TRACE_BROKER_MISSING(broker, x)
 
 #define FORWARD_DECL(Name) class Name##Data;
-HEAP_BROKER_OBJECT_LIST(FORWARD_DECL)
+HEAP_BROKER_SERIALIZED_OBJECT_LIST(FORWARD_DECL)
 #undef FORWARD_DECL
 
 // There are three kinds of ObjectData values.
@@ -71,6 +71,7 @@ enum ObjectDataKind {
   kSmi,
   kSerializedHeapObject,
   kUnserializedHeapObject,
+  kNeverSerializedHeapObject,
   kUnserializedReadOnlyHeapObject
 };
 
@@ -79,7 +80,8 @@ class AllowHandleAllocationIf {
   explicit AllowHandleAllocationIf(ObjectDataKind kind,
                                    JSHeapBroker::BrokerMode mode) {
     DCHECK_IMPLIES(mode == JSHeapBroker::BrokerMode::kSerialized,
-                   kind == kUnserializedReadOnlyHeapObject);
+                   kind == kUnserializedReadOnlyHeapObject ||
+                       kind == kNeverSerializedHeapObject);
     if (kind == kUnserializedHeapObject) maybe_allow_handle_.emplace();
   }
 
@@ -90,16 +92,15 @@ class AllowHandleAllocationIf {
 class AllowHandleDereferenceIf {
  public:
   explicit AllowHandleDereferenceIf(ObjectDataKind kind,
-                                    JSHeapBroker::BrokerMode mode) {
+                                    JSHeapBroker::BrokerMode mode)
+      : AllowHandleDereferenceIf(kind) {
     DCHECK_IMPLIES(mode == JSHeapBroker::BrokerMode::kSerialized,
-                   kind == kUnserializedReadOnlyHeapObject);
-    if (kind == kUnserializedHeapObject ||
-        kind == kUnserializedReadOnlyHeapObject)
-      maybe_allow_handle_.emplace();
+                   kind == kUnserializedReadOnlyHeapObject ||
+                       kind == kNeverSerializedHeapObject);
   }
 
   explicit AllowHandleDereferenceIf(ObjectDataKind kind) {
-    if (kind == kUnserializedHeapObject ||
+    if (kind == kUnserializedHeapObject || kind == kNeverSerializedHeapObject ||
         kind == kUnserializedReadOnlyHeapObject)
       maybe_allow_handle_.emplace();
   }
@@ -154,20 +155,26 @@ class ObjectData : public ZoneObject {
             broker->mode() == JSHeapBroker::kSerializing,
         broker->isolate()->handle_scope_data()->canonical_scope != nullptr);
     CHECK_IMPLIES(broker->mode() == JSHeapBroker::kSerialized,
-                  IsReadOnlyHeapObject(*object));
+                  (kind == kUnserializedReadOnlyHeapObject &&
+                   IsReadOnlyHeapObject(*object)) ||
+                      kind == kNeverSerializedHeapObject);
   }
 
-#define DECLARE_IS_AND_AS(Name) \
-  bool Is##Name() const;        \
-  Name##Data* As##Name();
-  HEAP_BROKER_OBJECT_LIST(DECLARE_IS_AND_AS)
-#undef DECLARE_IS_AND_AS
+#define DECLARE_IS(Name) bool Is##Name() const;
+  HEAP_BROKER_SERIALIZED_OBJECT_LIST(DECLARE_IS)
+  HEAP_BROKER_NEVER_SERIALIZED_OBJECT_LIST(DECLARE_IS)
+#undef DECLARE_IS
+
+#define DECLARE_AS(Name) Name##Data* As##Name();
+  HEAP_BROKER_SERIALIZED_OBJECT_LIST(DECLARE_AS)
+#undef DECLARE_AS
 
   Handle<Object> object() const { return object_; }
   ObjectDataKind kind() const { return kind_; }
   bool is_smi() const { return kind_ == kSmi; }
   bool should_access_heap() const {
     return kind_ == kUnserializedHeapObject ||
+           kind_ == kNeverSerializedHeapObject ||
            kind_ == kUnserializedReadOnlyHeapObject;
   }
 
@@ -772,7 +779,7 @@ class NativeContextData : public ContextData {
     return function_maps_;
   }
 
-  ScopeInfoData* scope_info() const {
+  ObjectData* scope_info() const {
     CHECK(serialized_);
     return scope_info_;
   }
@@ -787,7 +794,7 @@ class NativeContextData : public ContextData {
   BROKER_NATIVE_CONTEXT_FIELDS(DECL_MEMBER)
 #undef DECL_MEMBER
   ZoneVector<MapData*> function_maps_;
-  ScopeInfoData* scope_info_ = nullptr;
+  ObjectData* scope_info_ = nullptr;
 };
 
 class NameData : public HeapObjectData {
@@ -1662,45 +1669,6 @@ ObjectData* JSArrayData::GetOwnElement(JSHeapBroker* broker, uint32_t index,
   return result;
 }
 
-class ScopeInfoData : public HeapObjectData {
- public:
-  ScopeInfoData(JSHeapBroker* broker, ObjectData** storage,
-                Handle<ScopeInfo> object);
-
-  int context_length() const { return context_length_; }
-  bool has_outer_scope_info() const { return has_outer_scope_info_; }
-  int flags() const { return flags_; }
-
-  ScopeInfoData* outer_scope_info() const { return outer_scope_info_; }
-  void SerializeScopeInfoChain(JSHeapBroker* broker);
-
- private:
-  int const context_length_;
-  bool const has_outer_scope_info_;
-  int const flags_;
-
-  // Only serialized via SerializeScopeInfoChain.
-  ScopeInfoData* outer_scope_info_;
-};
-
-ScopeInfoData::ScopeInfoData(JSHeapBroker* broker, ObjectData** storage,
-                             Handle<ScopeInfo> object)
-    : HeapObjectData(broker, storage, object),
-      context_length_(object->ContextLength()),
-      has_outer_scope_info_(object->HasOuterScopeInfo()),
-      flags_(object->Flags()),
-      outer_scope_info_(nullptr) {}
-
-void ScopeInfoData::SerializeScopeInfoChain(JSHeapBroker* broker) {
-  if (outer_scope_info_) return;
-  if (!has_outer_scope_info_) return;
-  outer_scope_info_ =
-      broker
-          ->GetOrCreateData(Handle<ScopeInfo>::cast(object())->OuterScopeInfo())
-          ->AsScopeInfo();
-  outer_scope_info_->SerializeScopeInfoChain(broker);
-}
-
 class SharedFunctionInfoData : public HeapObjectData {
  public:
   SharedFunctionInfoData(JSHeapBroker* broker, ObjectData** storage,
@@ -1710,7 +1678,7 @@ class SharedFunctionInfoData : public HeapObjectData {
   int context_header_size() const { return context_header_size_; }
   BytecodeArrayData* GetBytecodeArray() const { return GetBytecodeArray_; }
   void SerializeFunctionTemplateInfo(JSHeapBroker* broker);
-  ScopeInfoData* scope_info() const { return scope_info_; }
+  ObjectData* scope_info() const { return scope_info_; }
   void SerializeScopeInfoChain(JSHeapBroker* broker);
   FunctionTemplateInfoData* function_template_info() const {
     return function_template_info_;
@@ -1741,7 +1709,7 @@ class SharedFunctionInfoData : public HeapObjectData {
 #undef DECL_MEMBER
   FunctionTemplateInfoData* function_template_info_;
   ZoneMap<int, JSArrayData*> template_objects_;
-  ScopeInfoData* scope_info_;
+  ObjectData* scope_info_;
 };
 
 SharedFunctionInfoData::SharedFunctionInfoData(
@@ -1781,12 +1749,8 @@ void SharedFunctionInfoData::SerializeFunctionTemplateInfo(
 
 void SharedFunctionInfoData::SerializeScopeInfoChain(JSHeapBroker* broker) {
   if (scope_info_) return;
-  scope_info_ =
-      broker
-          ->GetOrCreateData(
-              Handle<SharedFunctionInfo>::cast(object())->scope_info())
-          ->AsScopeInfo();
-  scope_info_->SerializeScopeInfoChain(broker);
+  scope_info_ = broker->GetOrCreateData(
+      Handle<SharedFunctionInfo>::cast(object())->synchronized_scope_info());
 }
 
 class SourceTextModuleData : public HeapObjectData {
@@ -1993,7 +1957,7 @@ class CodeData : public HeapObjectData {
   unsigned const inlined_bytecode_size_;
 };
 
-#define DEFINE_IS_AND_AS(Name)                                          \
+#define DEFINE_IS(Name)                                                 \
   bool ObjectData::Is##Name() const {                                   \
     if (should_access_heap()) {                                         \
       AllowHandleDereferenceIf allow_handle_dereference(kind());        \
@@ -2003,13 +1967,18 @@ class CodeData : public HeapObjectData {
     InstanceType instance_type =                                        \
         static_cast<const HeapObjectData*>(this)->GetMapInstanceType(); \
     return InstanceTypeChecker::Is##Name(instance_type);                \
-  }                                                                     \
-  Name##Data* ObjectData::As##Name() {                                  \
-    CHECK(Is##Name());                                                  \
-    return static_cast<Name##Data*>(this);                              \
   }
-HEAP_BROKER_OBJECT_LIST(DEFINE_IS_AND_AS)
-#undef DEFINE_IS_AND_AS
+HEAP_BROKER_SERIALIZED_OBJECT_LIST(DEFINE_IS)
+HEAP_BROKER_NEVER_SERIALIZED_OBJECT_LIST(DEFINE_IS)
+#undef DEFINE_IS
+
+#define DEFINE_AS(Name)                    \
+  Name##Data* ObjectData::As##Name() {     \
+    CHECK(Is##Name());                     \
+    return static_cast<Name##Data*>(this); \
+  }
+HEAP_BROKER_SERIALIZED_OBJECT_LIST(DEFINE_AS)
+#undef DEFINE_AS
 
 const JSObjectField& JSObjectData::GetInobjectField(int property_index) const {
   CHECK_LT(static_cast<size_t>(property_index), inobject_fields_.size());
@@ -2683,15 +2652,20 @@ ObjectData* JSHeapBroker::GetOrCreateData(Handle<Object> object) {
     } else if (IsReadOnlyHeapObject(*object)) {
       object_data = zone()->New<ObjectData>(this, data_storage, object,
                                             kUnserializedReadOnlyHeapObject);
-#define CREATE_DATA_IF_MATCH(name)                              \
+#define CREATE_DATA_FOR_DIRECT_READ(name)    \
+    } else if (object->Is##name()) {         \
+      object_data = zone()->New<ObjectData>( \
+          this, data_storage, object, kNeverSerializedHeapObject);
+    HEAP_BROKER_NEVER_SERIALIZED_OBJECT_LIST(CREATE_DATA_FOR_DIRECT_READ)
+#undef CREATE_DATA_FOR_DIRECT_READ
+#define CREATE_DATA_FOR_SERIALIZATION(name)                     \
     } else if (object->Is##name()) {                            \
       CHECK(SerializingAllowed());                              \
       AllowHandleAllocation handle_allocation;                  \
       object_data = zone()->New<name##Data>(this, data_storage, \
                                             Handle<name>::cast(object));
-
-      HEAP_BROKER_OBJECT_LIST(CREATE_DATA_IF_MATCH)
-#undef CREATE_DATA_IF_MATCH
+    HEAP_BROKER_SERIALIZED_OBJECT_LIST(CREATE_DATA_FOR_SERIALIZATION)
+#undef CREATE_DATA_FOR_SERIALIZATION
     } else {
       UNREACHABLE();
     }
@@ -2704,7 +2678,7 @@ ObjectData* JSHeapBroker::GetOrCreateData(Handle<Object> object) {
 // clang-format on
 
 ObjectData* JSHeapBroker::GetOrCreateData(Object object) {
-  return GetOrCreateData(handle(object, isolate()));
+  return GetOrCreateData(CanonicalPersistentHandle(object));
 }
 
 #define DEFINE_IS_AND_AS(Name)                                    \
@@ -2713,7 +2687,8 @@ ObjectData* JSHeapBroker::GetOrCreateData(Object object) {
     DCHECK(Is##Name());                                           \
     return Name##Ref(broker(), data());                           \
   }
-HEAP_BROKER_OBJECT_LIST(DEFINE_IS_AND_AS)
+HEAP_BROKER_SERIALIZED_OBJECT_LIST(DEFINE_IS_AND_AS)
+HEAP_BROKER_NEVER_SERIALIZED_OBJECT_LIST(DEFINE_IS_AND_AS)
 #undef DEFINE_IS_AND_AS
 
 bool ObjectRef::IsSmi() const { return data()->is_smi(); }
@@ -3257,8 +3232,6 @@ Handle<Object> JSHeapBroker::GetRootHandle(Object object) {
 
 #define IF_ACCESS_FROM_HEAP_C(holder, name)                              \
   if (data_->should_access_heap()) {                                     \
-    CHECK(broker()->mode() == JSHeapBroker::kDisabled ||                 \
-          ReadOnlyHeap::Contains(HeapObject::cast(*object())));          \
     AllowHandleAllocationIf handle_allocation(data_->kind(),             \
                                               broker()->mode());         \
     AllowHandleDereferenceIf allow_handle_dereference(data_->kind(),     \
@@ -3266,19 +3239,22 @@ Handle<Object> JSHeapBroker::GetRootHandle(Object object) {
     return object()->name();                                             \
   }
 
-#define IF_ACCESS_FROM_HEAP(holder, result, name)                            \
-  if (data_->kind() == ObjectDataKind::kUnserializedHeapObject) {            \
-    AllowHandleAllocationIf handle_allocation(data_->kind(),                 \
-                                              broker()->mode());             \
-    AllowHandleDereferenceIf handle_dereference(data_->kind(),               \
-                                                broker()->mode());           \
-    return result##Ref(broker(),                                             \
-                       handle(object()->name(), broker()->isolate()));       \
-  } else if (data_->kind() ==                                                \
-             ObjectDataKind::kUnserializedReadOnlyHeapObject) {              \
-    AllowHandleDereferenceIf handle_dereference(data_->kind(),               \
-                                                broker()->mode());           \
-    return result##Ref(broker(), broker()->GetRootHandle(object()->name())); \
+#define IF_ACCESS_FROM_HEAP(holder, result, name)                              \
+  if (data_->kind() == ObjectDataKind::kUnserializedHeapObject) {              \
+    AllowHandleAllocationIf handle_allocation(data_->kind(),                   \
+                                              broker()->mode());               \
+    AllowHandleDereferenceIf handle_dereference(data_->kind(),                 \
+                                                broker()->mode());             \
+    return result##Ref(broker(),                                               \
+                       handle(object()->name(), broker()->isolate()));         \
+  } else if (data_->kind() ==                                                  \
+             ObjectDataKind::kUnserializedReadOnlyHeapObject) {                \
+    AllowHandleDereferenceIf handle_dereference(data_->kind(),                 \
+                                                broker()->mode());             \
+    return result##Ref(broker(), broker()->GetRootHandle(object()->name()));   \
+  } else if (data_->kind() == ObjectDataKind::kNeverSerializedHeapObject) {    \
+    return result##Ref(broker(),                                               \
+                       broker()->CanonicalPersistentHandle(object()->name())); \
   }
 
 // Macros for definining a const getter that, depending on the broker mode,
@@ -3613,39 +3589,22 @@ int MapRef::GetInObjectProperties() const {
 
 int ScopeInfoRef::ContextLength() const {
   IF_ACCESS_FROM_HEAP_C(ScopeInfo, ContextLength);
-  return data()->AsScopeInfo()->context_length();
-}
-
-int ScopeInfoRef::Flags() const {
-  IF_ACCESS_FROM_HEAP_C(ScopeInfo, Flags);
-  return data()->AsScopeInfo()->flags();
+  UNREACHABLE();
 }
 
-bool ScopeInfoRef::HasContextExtension() const {
-  return ScopeInfo::HasContextExtensionSlotBit::decode(Flags());
+bool ScopeInfoRef::HasContextExtensionSlot() const {
+  IF_ACCESS_FROM_HEAP_C(ScopeInfo, HasContextExtensionSlot);
+  UNREACHABLE();
 }
 
 bool ScopeInfoRef::HasOuterScopeInfo() const {
   IF_ACCESS_FROM_HEAP_C(ScopeInfo, HasOuterScopeInfo);
-  return data()->AsScopeInfo()->has_outer_scope_info();
+  UNREACHABLE();
 }
 
 ScopeInfoRef ScopeInfoRef::OuterScopeInfo() const {
-  if (data_->should_access_heap()) {
-    DCHECK(data_->kind() != ObjectDataKind::kUnserializedReadOnlyHeapObject);
-    AllowHandleAllocationIf allow_handle_allocation(data()->kind(),
-                                                    broker()->mode());
-    AllowHandleDereferenceIf allow_handle_dereference(data()->kind(),
-                                                      broker()->mode());
-    return ScopeInfoRef(
-        broker(), handle(object()->OuterScopeInfo(), broker()->isolate()));
-  }
-  return ScopeInfoRef(broker(), data()->AsScopeInfo()->outer_scope_info());
-}
-
-void ScopeInfoRef::SerializeScopeInfoChain() {
-  CHECK_EQ(broker()->mode(), JSHeapBroker::kSerializing);
-  data()->AsScopeInfo()->SerializeScopeInfoChain(broker());
+  IF_ACCESS_FROM_HEAP(ScopeInfo, ScopeInfo, OuterScopeInfo);
+  UNREACHABLE();
 }
 
 bool StringRef::IsExternalString() const {
@@ -3686,8 +3645,8 @@ ScopeInfoRef NativeContextRef::scope_info() const {
                                                     broker()->mode());
     AllowHandleDereferenceIf allow_handle_dereference(data()->kind(),
                                                       broker()->mode());
-    return ScopeInfoRef(broker(),
-                        handle(object()->scope_info(), broker()->isolate()));
+    return ScopeInfoRef(
+        broker(), broker()->CanonicalPersistentHandle(object()->scope_info()));
   }
   return ScopeInfoRef(broker(), data()->AsNativeContext()->scope_info());
 }
@@ -4122,7 +4081,8 @@ Handle<Object> ObjectRef::object() const {
   }
 #endif  // DEBUG
 
-HEAP_BROKER_OBJECT_LIST(DEF_OBJECT_GETTER)
+HEAP_BROKER_SERIALIZED_OBJECT_LIST(DEF_OBJECT_GETTER)
+HEAP_BROKER_NEVER_SERIALIZED_OBJECT_LIST(DEF_OBJECT_GETTER)
 #undef DEF_OBJECT_GETTER
 
 JSHeapBroker* ObjectRef::broker() const { return broker_; }
@@ -4188,7 +4148,7 @@ void NativeContextData::Serialize(JSHeapBroker* broker) {
     function_maps_.push_back(broker->GetOrCreateData(context->get(i))->AsMap());
   }
 
-  scope_info_ = broker->GetOrCreateData(context->scope_info())->AsScopeInfo();
+  scope_info_ = broker->GetOrCreateData(context->scope_info());
 }
 
 void JSFunctionRef::Serialize() {
@@ -4291,8 +4251,8 @@ ScopeInfoRef SharedFunctionInfoRef::scope_info() const {
                                                     broker()->mode());
     AllowHandleDereferenceIf allow_handle_dereference(data()->kind(),
                                                       broker()->mode());
-    return ScopeInfoRef(broker(),
-                        handle(object()->scope_info(), broker()->isolate()));
+    return ScopeInfoRef(
+        broker(), broker()->CanonicalPersistentHandle(object()->scope_info()));
   }
   return ScopeInfoRef(broker(), data()->AsSharedFunctionInfo()->scope_info());
 }

src/compiler/pipeline.cc

@@ -1508,6 +1508,9 @@ struct TyperPhase {
     roots.push_back(data->jsgraph()->TrueConstant());
     roots.push_back(data->jsgraph()->FalseConstant());
 
+    // The typer inspects heap objects, so we need to unpark the local heap.
+    UnparkedScopeIfNeeded scope(data->broker());
+
     LoopVariableOptimizer induction_vars(data->jsgraph()->graph(),
                                          data->common(), temp_zone);
     if (FLAG_turbo_loop_variable) induction_vars.Run();

src/compiler/serializer-for-background-compilation.cc

@@ -1775,12 +1775,6 @@ void SerializerForBackgroundCompilation::VisitForInPrepare(
 
 void SerializerForBackgroundCompilation::ProcessCreateContext(
     interpreter::BytecodeArrayIterator* iterator, int scopeinfo_operand_index) {
-  Handle<ScopeInfo> scope_info =
-      Handle<ScopeInfo>::cast(iterator->GetConstantForIndexOperand(
-          scopeinfo_operand_index, broker()->isolate()));
-  ScopeInfoRef scope_info_ref(broker(), scope_info);
-  scope_info_ref.SerializeScopeInfoChain();
-
   Hints const& current_context_hints = environment()->current_context_hints();
   Hints result_hints;
 

src/objects/object-macros.h

@@ -79,6 +79,11 @@
 #define DECL_SYNCHRONIZED_INT_ACCESSORS(name) \
   DECL_SYNCHRONIZED_PRIMITIVE_ACCESSORS(name, int)
 
+#define DECL_SYNCHRONIZED_ACCESSORS(name, type) \
+  DECL_GETTER(synchronized_##name, type)        \
+  inline void set_synchronized_##name(          \
+      type value, WriteBarrierMode mode = UPDATE_WRITE_BARRIER);
+
 #define DECL_INT32_ACCESSORS(name) DECL_PRIMITIVE_ACCESSORS(name, int32_t)
 
 #define DECL_UINT16_ACCESSORS(name) \

src/objects/shared-function-info-inl.h

@@ -101,6 +101,8 @@ SYNCHRONIZED_ACCESSORS(SharedFunctionInfo, function_data, Object,
                        kFunctionDataOffset)
 ACCESSORS(SharedFunctionInfo, name_or_scope_info, Object,
           kNameOrScopeInfoOffset)
+SYNCHRONIZED_ACCESSORS(SharedFunctionInfo, synchronized_name_or_scope_info,
+                       Object, kNameOrScopeInfoOffset)
 ACCESSORS(SharedFunctionInfo, script_or_debug_info, HeapObject,
           kScriptOrDebugInfoOffset)
 
@@ -338,8 +340,16 @@ ScopeInfo SharedFunctionInfo::scope_info() const {
   return GetReadOnlyRoots().empty_scope_info();
 }
 
-void SharedFunctionInfo::set_scope_info(ScopeInfo scope_info,
-                                        WriteBarrierMode mode) {
+ScopeInfo SharedFunctionInfo::synchronized_scope_info() const {
+  Object maybe_scope_info = synchronized_name_or_scope_info();
+  if (maybe_scope_info.IsScopeInfo()) {
+    return ScopeInfo::cast(maybe_scope_info);
+  }
+  return GetReadOnlyRoots().empty_scope_info();
+}
+
+void SharedFunctionInfo::SetScopeInfo(ScopeInfo scope_info,
+                                      WriteBarrierMode mode) {
   // Move the existing name onto the ScopeInfo.
   Object name = name_or_scope_info();
   if (name.IsScopeInfo()) {
@@ -351,7 +361,7 @@ void SharedFunctionInfo::set_scope_info(ScopeInfo scope_info,
   if (HasInferredName() && inferred_name().length() != 0) {
     scope_info.SetInferredFunctionName(inferred_name());
   }
-  set_raw_scope_info(scope_info, mode);
+  set_synchronized_name_or_scope_info(scope_info, mode);
 }
 
 void SharedFunctionInfo::set_raw_scope_info(ScopeInfo scope_info,

src/objects/shared-function-info.h

@@ -216,12 +216,16 @@ class SharedFunctionInfo : public HeapObject {
   static const int kNotFound = -1;
 
   // [scope_info]: Scope info.
-  DECL_ACCESSORS(scope_info, ScopeInfo)
+  DECL_GETTER(scope_info, ScopeInfo)
+  DECL_GETTER(synchronized_scope_info, ScopeInfo)
 
   // Set scope_info without moving the existing name onto the ScopeInfo.
   inline void set_raw_scope_info(ScopeInfo scope_info,
                                  WriteBarrierMode mode = UPDATE_WRITE_BARRIER);
 
+  inline void SetScopeInfo(ScopeInfo scope_info,
+                           WriteBarrierMode mode = UPDATE_WRITE_BARRIER);
+
   inline bool is_script() const;
   inline bool needs_script_context() const;
 
@@ -662,6 +666,7 @@ class SharedFunctionInfo : public HeapObject {
   // [name_or_scope_info]: Function name string, kNoSharedNameSentinel or
   // ScopeInfo.
   DECL_ACCESSORS(name_or_scope_info, Object)
+  DECL_SYNCHRONIZED_ACCESSORS(name_or_scope_info, Object)
 
   // [outer scope info] The outer scope info, needed to lazily parse this
   // function.