cppgc: Refactor visitation 1/3

Split off MarkingState from MarkingVisitor.

With this CL the marking implementation is moved to "MarkingState"
which is the new bottleneck for marking a single object.
MarkingVisitor merely forwards to MarkingState, which knows how to set
the markbit and add the object to the worklist accordingly. This
allows to have a "UnifiedHeapMarkingVisitor" in future which can
easily reuse Marking to provide C++ marking.

Change-Id: I87ebbe37e8e8cd841e872cae9dc3490e2b55c4dd
Bug: chromium:1056170
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2270172Reviewed-by: Omer Katz <omerkatz@chromium.org>
Reviewed-by: Anton Bikineev <bikineev@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#68660}

BUILD.gn

@@ -4212,6 +4212,7 @@ v8_source_set("cppgc_base") {
     "src/heap/cppgc/logging.cc",
     "src/heap/cppgc/marker.cc",
     "src/heap/cppgc/marker.h",
+    "src/heap/cppgc/marking-state.h",
     "src/heap/cppgc/marking-visitor.cc",
     "src/heap/cppgc/marking-visitor.h",
     "src/heap/cppgc/object-allocator.cc",

src/heap/cppgc-js/cpp-heap.cc

@@ -14,6 +14,7 @@
 #include "src/heap/cppgc/heap-base.h"
 #include "src/heap/cppgc/heap-object-header.h"
 #include "src/heap/cppgc/marker.h"
+#include "src/heap/cppgc/marking-state.h"
 #include "src/heap/cppgc/marking-visitor.h"
 #include "src/heap/cppgc/object-allocator.h"
 #include "src/heap/cppgc/prefinalizer-handler.h"
@@ -72,8 +73,8 @@ UnifiedHeapMarker::UnifiedHeapMarker(cppgc::internal::HeapBase& heap)
     : cppgc::internal::Marker(heap) {}
 
 void UnifiedHeapMarker::AddObject(void* object) {
-  auto& header = cppgc::internal::HeapObjectHeader::FromPayload(object);
-  marking_visitor_->MarkObject(header);
+  mutator_marking_state_->MarkAndPush(
+      cppgc::internal::HeapObjectHeader::FromPayload(object));
 }
 
 }  // namespace

src/heap/cppgc/marker.cc

@@ -4,12 +4,15 @@
 
 #include "src/heap/cppgc/marker.h"
 
+#include <memory>
+
 #include "include/cppgc/internal/process-heap.h"
 #include "src/heap/cppgc/heap-object-header.h"
 #include "src/heap/cppgc/heap-page.h"
 #include "src/heap/cppgc/heap-visitor.h"
 #include "src/heap/cppgc/heap.h"
 #include "src/heap/cppgc/liveness-broker.h"
+#include "src/heap/cppgc/marking-state.h"
 #include "src/heap/cppgc/marking-visitor.h"
 #include "src/heap/cppgc/stats-collector.h"
 
@@ -99,7 +102,11 @@ bool DrainWorklistWithDeadline(v8::base::TimeTicks deadline, Worklist* worklist,
 constexpr int Marker::kMutatorThreadId;
 
 Marker::Marker(HeapBase& heap)
-    : heap_(heap), marking_visitor_(CreateMutatorThreadMarkingVisitor()) {}
+    : heap_(heap),
+      mutator_marking_state_(std::make_unique<MarkingState>(
+          heap, &marking_worklist_, &not_fully_constructed_worklist_,
+          &weak_callback_worklist_, Marker::kMutatorThreadId)),
+      marking_visitor_(CreateMutatorThreadMarkingVisitor()) {}
 
 Marker::~Marker() {
   // The fixed point iteration may have found not-fully-constructed objects.
@@ -147,7 +154,7 @@ void Marker::EnterAtomicPause(MarkingConfig config) {
 void Marker::LeaveAtomicPause() {
   ResetRememberedSet(heap());
   heap().stats_collector()->NotifyMarkingCompleted(
-      marking_visitor_->marked_bytes());
+      mutator_marking_state_->marked_bytes());
 }
 
 void Marker::FinishMarking(MarkingConfig config) {
@@ -199,8 +206,8 @@ bool Marker::AdvanceMarkingWithDeadline(v8::base::TimeDelta duration) {
     // callbacks.
     if (!DrainWorklistWithDeadline(
             deadline, &previously_not_fully_constructed_worklist_,
-            [visitor](NotFullyConstructedItem& item) {
-              visitor->DynamicallyMarkAddress(
+            [this](NotFullyConstructedItem& item) {
+              mutator_marking_state_->DynamicallyMarkAddress(
                   reinterpret_cast<ConstAddress>(item));
             },
             kMutatorThreadId))
@@ -208,25 +215,27 @@ bool Marker::AdvanceMarkingWithDeadline(v8::base::TimeDelta duration) {
 
     if (!DrainWorklistWithDeadline(
             deadline, &marking_worklist_,
-            [visitor](const MarkingItem& item) {
+            [this, visitor](const MarkingItem& item) {
               const HeapObjectHeader& header =
                   HeapObjectHeader::FromPayload(item.base_object_payload);
-              DCHECK(!MutatorThreadMarkingVisitor::IsInConstruction(header));
+              DCHECK(!header.IsInConstruction<
+                      HeapObjectHeader::AccessMode::kNonAtomic>());
               item.callback(visitor, item.base_object_payload);
-              visitor->AccountMarkedBytes(header);
+              mutator_marking_state_->AccountMarkedBytes(header);
             },
             kMutatorThreadId))
       return false;
 
     if (!DrainWorklistWithDeadline(
             deadline, &write_barrier_worklist_,
-            [visitor](HeapObjectHeader* header) {
+            [this, visitor](HeapObjectHeader* header) {
               DCHECK(header);
-              DCHECK(!MutatorThreadMarkingVisitor::IsInConstruction(*header));
+              DCHECK(!header->IsInConstruction<
+                      HeapObjectHeader::AccessMode::kNonAtomic>());
               const GCInfo& gcinfo =
                   GlobalGCInfoTable::GCInfoFromIndex(header->GetGCInfoIndex());
               gcinfo.trace(visitor, header->Payload());
-              visitor->AccountMarkedBytes(*header);
+              mutator_marking_state_->AccountMarkedBytes(*header);
             },
             kMutatorThreadId))
       return false;

src/heap/cppgc/marker.h

@@ -18,6 +18,7 @@ namespace internal {
 
 class HeapBase;
 class HeapObjectHeader;
+class MarkingState;
 class MutatorThreadMarkingVisitor;
 
 // Marking algorithm. Example for a valid call sequence creating the marking
@@ -115,6 +116,7 @@ class V8_EXPORT_PRIVATE Marker {
   WeakCallbackWorklist* weak_callback_worklist() {
     return &weak_callback_worklist_;
   }
+  MarkingState& marking_state() const { return *mutator_marking_state_.get(); }
 
   void ClearAllWorklistsForTesting();
 
@@ -134,6 +136,7 @@ class V8_EXPORT_PRIVATE Marker {
   HeapBase& heap_;
   MarkingConfig config_ = MarkingConfig::Default();
 
+  std::unique_ptr<MarkingState> mutator_marking_state_;
   std::unique_ptr<MutatorThreadMarkingVisitor> marking_visitor_;
 
   MarkingWorklist marking_worklist_;

src/heap/cppgc/marking-state.h

+// Copyright 2020 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.
+
+#ifndef V8_HEAP_CPPGC_MARKING_STATE_H_
+#define V8_HEAP_CPPGC_MARKING_STATE_H_
+
+#include "include/cppgc/trace-trait.h"
+#include "src/heap/cppgc/globals.h"
+#include "src/heap/cppgc/heap-object-header.h"
+#include "src/heap/cppgc/heap-page.h"
+#include "src/heap/cppgc/liveness-broker.h"
+#include "src/heap/cppgc/marker.h"
+
+namespace cppgc {
+namespace internal {
+
+// C++ marking implementation.
+class MarkingState {
+ public:
+  inline MarkingState(HeapBase& heap, Marker::MarkingWorklist*,
+                      Marker::NotFullyConstructedWorklist*,
+                      Marker::WeakCallbackWorklist*, int);
+
+  MarkingState(const MarkingState&) = delete;
+  MarkingState& operator=(const MarkingState&) = delete;
+
+  inline void MarkAndPush(const void*, TraceDescriptor);
+  inline void MarkAndPush(HeapObjectHeader&, TraceDescriptor);
+  inline void MarkAndPush(HeapObjectHeader&);
+
+  inline bool MarkNoPush(HeapObjectHeader&);
+
+  inline void DynamicallyMarkAddress(ConstAddress);
+
+  inline void RegisterWeakReferenceIfNeeded(const void*, TraceDescriptor,
+                                            WeakCallback, const void*);
+  inline void RegisterWeakCallback(WeakCallback, const void*);
+  inline void InvokeWeakRootsCallbackIfNeeded(const void*, TraceDescriptor,
+                                              WeakCallback, const void*);
+
+  inline void AccountMarkedBytes(const HeapObjectHeader&);
+  size_t marked_bytes() const { return marked_bytes_; }
+
+ private:
+#ifdef DEBUG
+  HeapBase& heap_;
+#endif  // DEBUG
+
+  Marker::MarkingWorklist::View marking_worklist_;
+  Marker::NotFullyConstructedWorklist::View not_fully_constructed_worklist_;
+  Marker::WeakCallbackWorklist::View weak_callback_worklist_;
+
+  size_t marked_bytes_ = 0;
+};
+
+MarkingState::MarkingState(
+    HeapBase& heap, Marker::MarkingWorklist* marking_worklist,
+    Marker::NotFullyConstructedWorklist* not_fully_constructed_worklist,
+    Marker::WeakCallbackWorklist* weak_callback_worklist, int task_id)
+    :
+#ifdef DEBUG
+      heap_(heap),
+#endif  // DEBUG
+      marking_worklist_(marking_worklist, task_id),
+      not_fully_constructed_worklist_(not_fully_constructed_worklist, task_id),
+      weak_callback_worklist_(weak_callback_worklist, task_id) {
+}
+
+void MarkingState::MarkAndPush(const void* object, TraceDescriptor desc) {
+  DCHECK_NOT_NULL(object);
+  if (desc.base_object_payload ==
+      cppgc::GarbageCollectedMixin::kNotFullyConstructedObject) {
+    // This means that the objects are not-yet-fully-constructed. See comments
+    // on GarbageCollectedMixin for how those objects are handled.
+    not_fully_constructed_worklist_.Push(object);
+    return;
+  }
+  MarkAndPush(HeapObjectHeader::FromPayload(
+                  const_cast<void*>(desc.base_object_payload)),
+              desc);
+}
+
+void MarkingState::MarkAndPush(HeapObjectHeader& header, TraceDescriptor desc) {
+  DCHECK_NOT_NULL(desc.callback);
+
+  if (header.IsInConstruction<HeapObjectHeader::AccessMode::kNonAtomic>()) {
+    not_fully_constructed_worklist_.Push(header.Payload());
+  } else if (MarkNoPush(header)) {
+    marking_worklist_.Push(desc);
+  }
+}
+
+bool MarkingState::MarkNoPush(HeapObjectHeader& header) {
+  // A GC should only mark the objects that belong in its heap.
+  DCHECK_EQ(&heap_, BasePage::FromPayload(&header)->heap());
+  // Never mark free space objects. This would e.g. hint to marking a promptly
+  // freed backing store.
+  DCHECK(!header.IsFree());
+  return header.TryMarkAtomic();
+}
+
+void MarkingState::DynamicallyMarkAddress(ConstAddress address) {
+  HeapObjectHeader& header =
+      BasePage::FromPayload(address)->ObjectHeaderFromInnerAddress(
+          const_cast<Address>(address));
+  DCHECK(!header.IsInConstruction<HeapObjectHeader::AccessMode::kNonAtomic>());
+  if (MarkNoPush(header)) {
+    marking_worklist_.Push(
+        {reinterpret_cast<void*>(header.Payload()),
+         GlobalGCInfoTable::GCInfoFromIndex(header.GetGCInfoIndex()).trace});
+  }
+}
+
+void MarkingState::MarkAndPush(HeapObjectHeader& header) {
+  MarkAndPush(
+      header,
+      {header.Payload(),
+       GlobalGCInfoTable::GCInfoFromIndex(header.GetGCInfoIndex()).trace});
+}
+
+void MarkingState::RegisterWeakReferenceIfNeeded(const void* object,
+                                                 TraceDescriptor desc,
+                                                 WeakCallback weak_callback,
+                                                 const void* parameter) {
+  // Filter out already marked values. The write barrier for WeakMember
+  // ensures that any newly set value after this point is kept alive and does
+  // not require the callback.
+  if (desc.base_object_payload !=
+          cppgc::GarbageCollectedMixin::kNotFullyConstructedObject &&
+      HeapObjectHeader::FromPayload(desc.base_object_payload)
+          .IsMarked<HeapObjectHeader::AccessMode::kAtomic>())
+    return;
+  RegisterWeakCallback(weak_callback, parameter);
+}
+
+void MarkingState::InvokeWeakRootsCallbackIfNeeded(const void* object,
+                                                   TraceDescriptor desc,
+                                                   WeakCallback weak_callback,
+                                                   const void* parameter) {
+  if (desc.base_object_payload ==
+      cppgc::GarbageCollectedMixin::kNotFullyConstructedObject) {
+    // This method is only called at the end of marking. If the object is in
+    // construction, then it should be reachable from the stack.
+    return;
+  }
+  // Since weak roots are only traced at the end of marking, we can execute
+  // the callback instead of registering it.
+  weak_callback(LivenessBrokerFactory::Create(), parameter);
+}
+
+void MarkingState::RegisterWeakCallback(WeakCallback callback,
+                                        const void* object) {
+  weak_callback_worklist_.Push({callback, object});
+}
+
+void MarkingState::AccountMarkedBytes(const HeapObjectHeader& header) {
+  marked_bytes_ +=
+      header.IsLargeObject()
+          ? reinterpret_cast<const LargePage*>(BasePage::FromPayload(&header))
+                ->PayloadSize()
+          : header.GetSize();
+}
+
+}  // namespace internal
+}  // namespace cppgc
+
+#endif  // V8_HEAP_CPPGC_MARKING_STATE_H_

src/heap/cppgc/marking-visitor.cc

@@ -9,58 +9,24 @@
 #include "src/heap/cppgc/heap-page.h"
 #include "src/heap/cppgc/heap.h"
 #include "src/heap/cppgc/liveness-broker.h"
+#include "src/heap/cppgc/marking-state.h"
 
 namespace cppgc {
 namespace internal {
 
-// static
-bool MarkingVisitor::IsInConstruction(const HeapObjectHeader& header) {
-  return header.IsInConstruction<HeapObjectHeader::AccessMode::kNonAtomic>();
-}
-
-MarkingVisitor::MarkingVisitor(
-    HeapBase& heap, Marker::MarkingWorklist* marking_worklist,
-    Marker::NotFullyConstructedWorklist* not_fully_constructed_worklist,
-    Marker::WeakCallbackWorklist* weak_callback_worklist, int task_id)
+MarkingVisitor::MarkingVisitor(HeapBase& heap, MarkingState& marking_state)
     : ConservativeTracingVisitor(heap, *heap.page_backend()),
-      marking_worklist_(marking_worklist, task_id),
-      not_fully_constructed_worklist_(not_fully_constructed_worklist, task_id),
-      weak_callback_worklist_(weak_callback_worklist, task_id) {}
-
-void MarkingVisitor::AccountMarkedBytes(const HeapObjectHeader& header) {
-  marked_bytes_ +=
-      header.IsLargeObject()
-          ? reinterpret_cast<const LargePage*>(BasePage::FromPayload(&header))
-                ->PayloadSize()
-          : header.GetSize();
-}
+      marking_state_(marking_state) {}
 
 void MarkingVisitor::Visit(const void* object, TraceDescriptor desc) {
-  DCHECK_NOT_NULL(object);
-  if (desc.base_object_payload ==
-      cppgc::GarbageCollectedMixin::kNotFullyConstructedObject) {
-    // This means that the objects are not-yet-fully-constructed. See comments
-    // on GarbageCollectedMixin for how those objects are handled.
-    not_fully_constructed_worklist_.Push(object);
-    return;
-  }
-  MarkHeader(&HeapObjectHeader::FromPayload(
-                 const_cast<void*>(desc.base_object_payload)),
-             desc);
+  marking_state_.MarkAndPush(object, desc);
 }
 
 void MarkingVisitor::VisitWeak(const void* object, TraceDescriptor desc,
                                WeakCallback weak_callback,
                                const void* weak_member) {
-  // Filter out already marked values. The write barrier for WeakMember
-  // ensures that any newly set value after this point is kept alive and does
-  // not require the callback.
-  if (desc.base_object_payload !=
-          cppgc::GarbageCollectedMixin::kNotFullyConstructedObject &&
-      HeapObjectHeader::FromPayload(desc.base_object_payload)
-          .IsMarked<HeapObjectHeader::AccessMode::kAtomic>())
-    return;
-  RegisterWeakCallback(weak_callback, weak_member);
+  marking_state_.RegisterWeakReferenceIfNeeded(object, desc, weak_callback,
+                                               weak_member);
 }
 
 void MarkingVisitor::VisitRoot(const void* object, TraceDescriptor desc) {
@@ -70,15 +36,8 @@ void MarkingVisitor::VisitRoot(const void* object, TraceDescriptor desc) {
 void MarkingVisitor::VisitWeakRoot(const void* object, TraceDescriptor desc,
                                    WeakCallback weak_callback,
                                    const void* weak_root) {
-  if (desc.base_object_payload ==
-      cppgc::GarbageCollectedMixin::kNotFullyConstructedObject) {
-    // This method is only called at the end of marking. If the object is in
-    // construction, then it should be reachable from the stack.
-    return;
-  }
-  // Since weak roots are only traced at the end of marking, we can execute
-  // the callback instead of registering it.
-  weak_callback(LivenessBrokerFactory::Create(), weak_root);
+  marking_state_.InvokeWeakRootsCallbackIfNeeded(object, desc, weak_callback,
+                                                 weak_root);
 }
 
 void MarkingVisitor::VisitPointer(const void* address) {
@@ -87,69 +46,18 @@ void MarkingVisitor::VisitPointer(const void* address) {
 
 void MarkingVisitor::VisitConservatively(HeapObjectHeader& header,
                                          TraceConservativelyCallback callback) {
-  MarkHeaderNoTracing(&header);
+  marking_state_.MarkNoPush(header);
   callback(this, header);
-  AccountMarkedBytes(header);
-}
-
-void MarkingVisitor::MarkHeader(HeapObjectHeader* header,
-                                TraceDescriptor desc) {
-  DCHECK(header);
-  DCHECK_NOT_NULL(desc.callback);
-
-  if (IsInConstruction(*header)) {
-    not_fully_constructed_worklist_.Push(header->Payload());
-  } else if (MarkHeaderNoTracing(header)) {
-    marking_worklist_.Push(desc);
-  }
-}
-
-bool MarkingVisitor::MarkHeaderNoTracing(HeapObjectHeader* header) {
-  DCHECK(header);
-  // A GC should only mark the objects that belong in its heap.
-  DCHECK_EQ(&heap_, BasePage::FromPayload(header)->heap());
-  // Never mark free space objects. This would e.g. hint to marking a promptly
-  // freed backing store.
-  DCHECK(!header->IsFree());
-
-  return header->TryMarkAtomic();
+  marking_state_.AccountMarkedBytes(header);
 }
 
 void MarkingVisitor::RegisterWeakCallback(WeakCallback callback,
                                           const void* object) {
-  weak_callback_worklist_.Push({callback, object});
-}
-
-void MarkingVisitor::FlushWorklists() {
-  marking_worklist_.FlushToGlobal();
-  not_fully_constructed_worklist_.FlushToGlobal();
-  weak_callback_worklist_.FlushToGlobal();
-}
-
-void MarkingVisitor::DynamicallyMarkAddress(ConstAddress address) {
-  HeapObjectHeader& header =
-      BasePage::FromPayload(address)->ObjectHeaderFromInnerAddress(
-          const_cast<Address>(address));
-  DCHECK(!IsInConstruction(header));
-  if (MarkHeaderNoTracing(&header)) {
-    marking_worklist_.Push(
-        {reinterpret_cast<void*>(header.Payload()),
-         GlobalGCInfoTable::GCInfoFromIndex(header.GetGCInfoIndex()).trace});
-  }
-}
-
-void MarkingVisitor::MarkObject(HeapObjectHeader& header) {
-  MarkHeader(
-      &header,
-      {header.Payload(),
-       GlobalGCInfoTable::GCInfoFromIndex(header.GetGCInfoIndex()).trace});
+  marking_state_.RegisterWeakCallback(callback, object);
 }
 
 MutatorThreadMarkingVisitor::MutatorThreadMarkingVisitor(Marker* marker)
-    : MarkingVisitor(marker->heap(), marker->marking_worklist(),
-                     marker->not_fully_constructed_worklist(),
-                     marker->weak_callback_worklist(),
-                     Marker::kMutatorThreadId) {}
+    : MarkingVisitor(marker->heap(), marker->marking_state()) {}
 
 }  // namespace internal
 }  // namespace cppgc

src/heap/cppgc/marking-visitor.h

@@ -5,66 +5,42 @@
 #ifndef V8_HEAP_CPPGC_MARKING_VISITOR_H_
 #define V8_HEAP_CPPGC_MARKING_VISITOR_H_
 
-#include "include/cppgc/source-location.h"
 #include "include/cppgc/trace-trait.h"
-#include "include/v8config.h"
 #include "src/base/macros.h"
 #include "src/heap/base/stack.h"
-#include "src/heap/cppgc/globals.h"
-#include "src/heap/cppgc/heap.h"
-#include "src/heap/cppgc/marker.h"
 #include "src/heap/cppgc/visitor.h"
 
 namespace cppgc {
 namespace internal {
 
-class BasePage;
+class HeapBase;
 class HeapObjectHeader;
+class Marker;
+class MarkingState;
 
 class MarkingVisitor : public ConservativeTracingVisitor,
                        public heap::base::StackVisitor {
  public:
-  MarkingVisitor(HeapBase&, Marker::MarkingWorklist*,
-                 Marker::NotFullyConstructedWorklist*,
-                 Marker::WeakCallbackWorklist*, int);
+  MarkingVisitor(HeapBase&, MarkingState&);
   virtual ~MarkingVisitor() = default;
 
   MarkingVisitor(const MarkingVisitor&) = delete;
   MarkingVisitor& operator=(const MarkingVisitor&) = delete;
 
-  void FlushWorklists();
-
-  void DynamicallyMarkAddress(ConstAddress);
-  void MarkObject(HeapObjectHeader&);
-
-  void AccountMarkedBytes(const HeapObjectHeader&);
-  size_t marked_bytes() const { return marked_bytes_; }
-
-  static bool IsInConstruction(const HeapObjectHeader&);
-
- protected:
-  void Visit(const void*, TraceDescriptor) override;
-  void VisitWeak(const void*, TraceDescriptor, WeakCallback,
-                 const void*) override;
-  void VisitRoot(const void*, TraceDescriptor) override;
+ private:
+  void Visit(const void*, TraceDescriptor) final;
+  void VisitWeak(const void*, TraceDescriptor, WeakCallback, const void*) final;
+  void VisitRoot(const void*, TraceDescriptor) final;
   void VisitWeakRoot(const void*, TraceDescriptor, WeakCallback,
-                     const void*) override;
+                     const void*) final;
   void VisitConservatively(HeapObjectHeader&,
-                           TraceConservativelyCallback) override;
+                           TraceConservativelyCallback) final;
+  void RegisterWeakCallback(WeakCallback, const void*) final;
 
   // StackMarker interface.
   void VisitPointer(const void*) override;
 
- private:
-  void MarkHeader(HeapObjectHeader*, TraceDescriptor);
-  bool MarkHeaderNoTracing(HeapObjectHeader*);
-  void RegisterWeakCallback(WeakCallback, const void*) override;
-
-  Marker::MarkingWorklist::View marking_worklist_;
-  Marker::NotFullyConstructedWorklist::View not_fully_constructed_worklist_;
-  Marker::WeakCallbackWorklist::View weak_callback_worklist_;
-
-  size_t marked_bytes_ = 0;
+  MarkingState& marking_state_;
 };
 
 class V8_EXPORT_PRIVATE MutatorThreadMarkingVisitor : public MarkingVisitor {

src/heap/cppgc/write-barrier.cc

@@ -34,7 +34,9 @@ void MarkValue(const BasePage* page, Marker* marker, const void* value) {
 
   DCHECK(marker);
 
-  if (V8_UNLIKELY(MutatorThreadMarkingVisitor::IsInConstruction(header))) {
+  if (V8_UNLIKELY(
+          header
+              .IsInConstruction<HeapObjectHeader::AccessMode::kNonAtomic>())) {
     // It is assumed that objects on not_fully_constructed_worklist_ are not
     // marked.
     header.Unmark();

test/unittests/heap/cppgc/marking-visitor-unittest.cc

@@ -11,6 +11,7 @@
 #include "src/heap/cppgc/globals.h"
 #include "src/heap/cppgc/heap-object-header.h"
 #include "src/heap/cppgc/marker.h"
+#include "src/heap/cppgc/marking-state.h"
 #include "test/unittests/heap/cppgc/tests.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ -47,11 +48,10 @@ class GCedWithMixin : public GarbageCollected<GCedWithMixin>, public Mixin {
 }  // namespace
 
 TEST_F(MarkingVisitorTest, MarkedBytesAreInitiallyZero) {
-  MutatorThreadMarkingVisitor visitor(GetMarker());
-  EXPECT_EQ(0u, visitor.marked_bytes());
+  EXPECT_EQ(0u, GetMarker()->marking_state().marked_bytes());
 }
 
-// Strong refernces are marked.
+// Strong references are marked.
 
 TEST_F(MarkingVisitorTest, MarkMember) {
   Member<GCed> object(MakeGarbageCollected<GCed>(GetAllocationHandle()));