Revert "[gc][static-roots] Don't access markbits on R/O pages"

This reverts commit a2f63f1886.

Reason for revert: It breaks chromium integration tests https://ci.chromium.org/ui/p/v8/builders/ci/V8%20Blink%20Linux/22574/overview

Original change's description:
> [gc][static-roots] Don't access markbits on R/O pages
>
> Markbits on read only pages are initialized BLACK and never change. For
> any practical purposes they are unused.
>
> This CL prevents any access to the markbits of these pages. This is a
> precursor to removing them entirely from the page to make room for
> static roots.
>
> Bug: v8:13466
> Change-Id: I61d3f6d9bbca750d0f34475859b34ff44f7fec1e
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/4212397
> Reviewed-by: Dominik Inführ <dinfuehr@chromium.org>
> Auto-Submit: Olivier Flückiger <olivf@chromium.org>
> Commit-Queue: Olivier Flückiger <olivf@chromium.org>
> Cr-Commit-Position: refs/heads/main@{#85665}

Bug: v8:13466
Change-Id: Icda4be38da984fdefd40301238c361a86f912141
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/4225673
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Auto-Submit: Ilya Rezvov <irezvov@chromium.org>
Owners-Override: Ilya Rezvov <irezvov@chromium.org>
Commit-Queue: Ilya Rezvov <irezvov@chromium.org>
Cr-Commit-Position: refs/heads/main@{#85695}

src/heap/basic-memory-chunk.cc

@@ -64,10 +64,8 @@ BasicMemoryChunk::BasicMemoryChunk(Heap* heap, BaseSpace* space,
       high_water_mark_(area_start - reinterpret_cast<Address>(this)),
       owner_(space),
       reservation_(std::move(reservation)) {
-  if (space->identity() != RO_SPACE) {
   marking_bitmap<AccessMode::NON_ATOMIC>()->Clear();
 }
-}
 
 bool BasicMemoryChunk::InOldSpace() const {
   return owner()->identity() == OLD_SPACE;

src/heap/basic-memory-chunk.h

@@ -306,8 +306,6 @@ class BasicMemoryChunk {
 
   template <AccessMode mode>
   ConcurrentBitmap<mode>* marking_bitmap() const {
-    // TODO(olivf) Change to DCHECK once we have some coverage
-    CHECK(!InReadOnlySpace());
     return static_cast<ConcurrentBitmap<mode>*>(
         Bitmap::FromAddress(address() + kMarkingBitmapOffset));
   }

src/heap/concurrent-marking.cc

@@ -263,7 +263,7 @@ class YoungGenerationConcurrentMarkingVisitor final
         marking_state_(heap->isolate(), memory_chunk_data) {}
 
   bool ShouldMarkObject(HeapObject object) const {
-    return !object.InSharedHeap() && !object.InReadOnlySpace();
+    return !object.InSharedHeap();
   }
 
   void SynchronizePageAccess(HeapObject heap_object) {
@@ -787,7 +787,6 @@ void ConcurrentMarking::RunMajor(JobDelegate* delegate,
           done = true;
           break;
         }
-        DCHECK(!object.InReadOnlySpace());
         objects_processed++;
 
         Address new_space_top = kNullAddress;

src/heap/mark-compact-inl.h

@@ -86,7 +86,6 @@ void MarkCompactCollector::AddTransitionArray(TransitionArray array) {
 }
 
 bool MarkCompactCollector::ShouldMarkObject(HeapObject object) const {
-  if (object.InReadOnlySpace()) return false;
   if (V8_LIKELY(!uses_shared_heap_)) return true;
   if (v8_flags.shared_space) {
     if (is_shared_heap_isolate_) return true;

src/heap/mark-compact.cc

@@ -293,8 +293,7 @@ class FullMarkingVerifier : public MarkingVerifier {
       CHECK(heap_->SharedHeapContains(heap_object));
     }
 
-    CHECK(heap_object.InReadOnlySpace() ||
-          marking_state_->IsBlack(heap_object));
+    CHECK(marking_state_->IsBlack(heap_object));
   }
 
   V8_INLINE bool ShouldVerifyObject(HeapObject heap_object) {
@@ -627,6 +626,14 @@ void MarkCompactCollector::CollectGarbage() {
 }
 
 #ifdef VERIFY_HEAP
+void MarkCompactCollector::VerifyMarkbitsAreDirty(ReadOnlySpace* space) {
+  ReadOnlyHeapObjectIterator iterator(space);
+  for (HeapObject object = iterator.Next(); !object.is_null();
+       object = iterator.Next()) {
+    CHECK(non_atomic_marking_state()->IsBlack(object));
+  }
+}
+
 void MarkCompactCollector::VerifyMarkbitsAreClean(PagedSpaceBase* space) {
   for (Page* p : *space) {
     CHECK(non_atomic_marking_state()->bitmap(p)->IsClean());
@@ -660,6 +667,9 @@ void MarkCompactCollector::VerifyMarkbitsAreClean() {
   VerifyMarkbitsAreClean(heap_->old_space());
   VerifyMarkbitsAreClean(heap_->code_space());
   VerifyMarkbitsAreClean(heap_->new_space());
+  // Read-only space should always be black since we never collect any objects
+  // in it or linked from it.
+  VerifyMarkbitsAreDirty(heap_->read_only_space());
   VerifyMarkbitsAreClean(heap_->lo_space());
   VerifyMarkbitsAreClean(heap_->code_lo_space());
   VerifyMarkbitsAreClean(heap_->new_lo_space());
@@ -1328,8 +1338,7 @@ class InternalizedStringTableCleaner final : public RootVisitor {
       if (o.IsHeapObject()) {
         HeapObject heap_object = HeapObject::cast(o);
         DCHECK(!Heap::InYoungGeneration(heap_object));
-        if (!heap_object.InReadOnlySpace() &&
-            marking_state->IsWhite(heap_object)) {
+        if (marking_state->IsWhite(heap_object)) {
           pointers_removed_++;
           // Set the entry to the_hole_value (as deleted).
           p.store(StringTable::deleted_element());
@@ -2721,8 +2730,7 @@ bool ShouldRetainMap(MarkingState* marking_state, Map map, int age) {
   }
   Object constructor = map.GetConstructor();
   if (!constructor.IsHeapObject() ||
-      (!HeapObject::cast(constructor).InReadOnlySpace() &&
-       marking_state->IsWhite(HeapObject::cast(constructor)))) {
+      marking_state->IsWhite(HeapObject::cast(constructor))) {
     // The constructor is dead, no new objects with this map can
     // be created. Do not retain this map.
     return false;
@@ -2761,8 +2769,7 @@ void MarkCompactCollector::RetainMaps() {
         }
         Object prototype = map.prototype();
         if (age > 0 && prototype.IsHeapObject() &&
-            (!HeapObject::cast(prototype).InReadOnlySpace() &&
-             marking_state()->IsWhite(HeapObject::cast(prototype)))) {
+            marking_state()->IsWhite(HeapObject::cast(prototype))) {
           // The prototype is not marked, age the map.
           new_age = age - 1;
         } else {
@@ -2974,10 +2981,7 @@ class StringForwardingTableCleaner final {
     String original_string = String::cast(original);
     if (marking_state_->IsBlack(original_string)) {
       Object forward = record->ForwardStringObjectOrHash(isolate_);
-      if (!forward.IsHeapObject() ||
-          HeapObject::cast(forward).InReadOnlySpace()) {
-        return;
-      }
+      if (!forward.IsHeapObject()) return;
       marking_state_->WhiteToBlack(HeapObject::cast(forward));
     } else {
       DisposeExternalResource(record);
@@ -3033,15 +3037,11 @@ class StringForwardingTableCleaner final {
                       StringForwardingTable::Record* record) {
     if (original_string.IsInternalizedString()) return;
     Object forward = record->ForwardStringObjectOrHash(isolate_);
-    if (!forward.IsHeapObject()) {
-      return;
-    }
+    if (!forward.IsHeapObject()) return;
     String forward_string = String::cast(forward);
 
     // Mark the forwarded string to keep it alive.
-    if (!forward_string.InReadOnlySpace()) {
     marking_state_->WhiteToBlack(forward_string);
-    }
     // Transition the original string to a ThinString and override the
     // forwarding index with the correct hash.
     original_string.MakeThin(isolate_, forward_string);
@@ -3680,8 +3680,7 @@ void MarkCompactCollector::ClearJSWeakRefs() {
   JSWeakRef weak_ref;
   while (local_weak_objects()->js_weak_refs_local.Pop(&weak_ref)) {
     HeapObject target = HeapObject::cast(weak_ref.target());
-    if (!target.InReadOnlySpace() &&
-        !non_atomic_marking_state()->IsBlackOrGrey(target)) {
+    if (!non_atomic_marking_state()->IsBlackOrGrey(target)) {
       weak_ref.set_target(ReadOnlyRoots(isolate()).undefined_value());
     } else {
       // The value of the JSWeakRef is alive.
@@ -3698,8 +3697,7 @@ void MarkCompactCollector::ClearJSWeakRefs() {
       }
     };
     HeapObject target = HeapObject::cast(weak_cell.target());
-    if (!target.InReadOnlySpace() &&
-        !non_atomic_marking_state()->IsBlackOrGrey(target)) {
+    if (!non_atomic_marking_state()->IsBlackOrGrey(target)) {
       DCHECK(target.CanBeHeldWeakly());
       // The value of the WeakCell is dead.
       JSFinalizationRegistry finalization_registry =
@@ -3721,8 +3719,7 @@ void MarkCompactCollector::ClearJSWeakRefs() {
     }
 
     HeapObject unregister_token = weak_cell.unregister_token();
-    if (!unregister_token.InReadOnlySpace() &&
-        !non_atomic_marking_state()->IsBlackOrGrey(unregister_token)) {
+    if (!non_atomic_marking_state()->IsBlackOrGrey(unregister_token)) {
       DCHECK(unregister_token.CanBeHeldWeakly());
       // The unregister token is dead. Remove any corresponding entries in the
       // key map. Multiple WeakCell with the same token will have all their

src/heap/mark-compact.h

@@ -422,6 +422,7 @@ class MarkCompactCollector final : public CollectorBase {
   void VerifyMarking();
 #ifdef VERIFY_HEAP
   void VerifyMarkbitsAreClean();
+  void VerifyMarkbitsAreDirty(ReadOnlySpace* space);
   void VerifyMarkbitsAreClean(PagedSpaceBase* space);
   void VerifyMarkbitsAreClean(NewSpace* space);
   void VerifyMarkbitsAreClean(LargeObjectSpace* space);

src/heap/marking-barrier-inl.h

@@ -14,8 +14,6 @@ namespace v8 {
 namespace internal {
 
 void MarkingBarrier::MarkValue(HeapObject host, HeapObject value) {
-  if (value.InReadOnlySpace()) return;
-
   DCHECK(IsCurrentMarkingBarrier(host));
   DCHECK(is_activated_ || shared_heap_worklist_.has_value());
 

src/heap/marking-visitor-inl.h

@@ -257,7 +257,6 @@ int MarkingVisitorBase<ConcreteVisitor, MarkingState>::
     if (end < size) {
       // The object can be pushed back onto the marking worklist only after
       // progress bar was updated.
-      DCHECK(ShouldMarkObject(object));
       local_marking_worklists_->Push(object);
     }
   }
@@ -373,8 +372,7 @@ int MarkingVisitorBase<ConcreteVisitor, MarkingState>::VisitEphemeronHashTable(
     // WeakMaps and WeakSets and therefore cannot be ephemeron keys. See also
     // MarkCompactCollector::ProcessEphemeron.
     DCHECK(!key.InSharedWritableHeap());
-    if (key.InReadOnlySpace() ||
-        concrete_visitor()->marking_state()->IsBlackOrGrey(key)) {
+    if (concrete_visitor()->marking_state()->IsBlackOrGrey(key)) {
       VisitPointer(table, value_slot);
     } else {
       Object value_obj = table.ValueAt(i);
@@ -407,8 +405,7 @@ int MarkingVisitorBase<ConcreteVisitor, MarkingState>::VisitJSWeakRef(
   if (weak_ref.target().IsHeapObject()) {
     HeapObject target = HeapObject::cast(weak_ref.target());
     SynchronizePageAccess(target);
-    if (target.InReadOnlySpace() ||
-        concrete_visitor()->marking_state()->IsBlackOrGrey(target)) {
+    if (concrete_visitor()->marking_state()->IsBlackOrGrey(target)) {
       // Record the slot inside the JSWeakRef, since the
       // VisitJSObjectSubclass above didn't visit it.
       ObjectSlot slot = weak_ref.RawField(JSWeakRef::kTargetOffset);
@@ -435,10 +432,8 @@ int MarkingVisitorBase<ConcreteVisitor, MarkingState>::VisitWeakCell(
   HeapObject unregister_token = weak_cell.relaxed_unregister_token();
   SynchronizePageAccess(target);
   SynchronizePageAccess(unregister_token);
-  if ((target.InReadOnlySpace() ||
-       concrete_visitor()->marking_state()->IsBlackOrGrey(target)) &&
-      (unregister_token.InReadOnlySpace() ||
-       concrete_visitor()->marking_state()->IsBlackOrGrey(unregister_token))) {
+  if (concrete_visitor()->marking_state()->IsBlackOrGrey(target) &&
+      concrete_visitor()->marking_state()->IsBlackOrGrey(unregister_token)) {
     // Record the slots inside the WeakCell, since the IterateBody above
     // didn't visit it.
     ObjectSlot slot = weak_cell.RawField(WeakCell::kTargetOffset);
@@ -463,7 +458,6 @@ int MarkingVisitorBase<ConcreteVisitor, MarkingState>::VisitWeakCell(
 template <typename ConcreteVisitor, typename MarkingState>
 int MarkingVisitorBase<ConcreteVisitor, MarkingState>::MarkDescriptorArrayBlack(
     DescriptorArray descriptors) {
-  if (descriptors.InReadOnlySpace()) return 0;
   concrete_visitor()->marking_state()->WhiteToGrey(descriptors);
   if (concrete_visitor()->marking_state()->GreyToBlack(descriptors)) {
     VisitMapPointer(descriptors);

src/heap/marking-visitor.h

@@ -122,7 +122,6 @@ class MarkingVisitorBase : public HeapVisitor<int, ConcreteVisitor> {
   }
 
   bool ShouldMarkObject(HeapObject object) const {
-    if (object.InReadOnlySpace()) return false;
     if (should_mark_shared_heap_) return true;
     return !object.InSharedHeap();
   }

src/heap/object-stats.cc

@@ -846,12 +846,8 @@ bool ObjectStatsCollectorImpl::IsCowArray(FixedArrayBase array) {
 }
 
 bool ObjectStatsCollectorImpl::SameLiveness(HeapObject obj1, HeapObject obj2) {
-  if (obj1.is_null() || obj2.is_null()) return true;
-  auto col1 = obj1.InReadOnlySpace() ? Marking::ObjectColor::BLACK_OBJECT
-                                     : marking_state_->Color(obj1);
-  auto col2 = obj2.InReadOnlySpace() ? Marking::ObjectColor::BLACK_OBJECT
-                                     : marking_state_->Color(obj2);
-  return col1 == col2;
+  return obj1.is_null() || obj2.is_null() ||
+         marking_state_->Color(obj1) == marking_state_->Color(obj2);
 }
 
 void ObjectStatsCollectorImpl::RecordVirtualMapDetails(Map map) {
@@ -1097,7 +1093,7 @@ class ObjectStatsVisitor {
         phase_(phase) {}
 
   void Visit(HeapObject obj) {
-    if (obj.InReadOnlySpace() || marking_state_->IsBlack(obj)) {
+    if (marking_state_->IsBlack(obj)) {
       live_collector_->CollectStatistics(
           obj, phase_, ObjectStatsCollectorImpl::CollectFieldStats::kYes);
     } else {

src/heap/read-only-spaces.cc

@@ -338,6 +338,7 @@ ReadOnlyPage::ReadOnlyPage(Heap* heap, BaseSpace* space, size_t chunk_size,
                        std::move(reservation)) {
   allocated_bytes_ = 0;
   SetFlags(Flag::NEVER_EVACUATE | Flag::READ_ONLY_HEAP);
+  heap->non_atomic_marking_state()->bitmap(this)->MarkAllBits();
 }
 
 void ReadOnlyPage::MakeHeaderRelocatable() {
@@ -544,6 +545,11 @@ void ReadOnlySpace::FreeLinearAllocationArea() {
     return;
   }
 
+  // Clear the bits in the unused black area.
+  ReadOnlyPage* page = pages_.back();
+  heap()->marking_state()->bitmap(page)->ClearRange(
+      page->AddressToMarkbitIndex(top_), page->AddressToMarkbitIndex(limit_));
+
   heap()->CreateFillerObjectAt(top_, static_cast<int>(limit_ - top_));
 
   BasicMemoryChunk::UpdateHighWaterMark(top_);
@@ -656,9 +662,15 @@ AllocationResult ReadOnlySpace::AllocateRawUnaligned(int size_in_bytes) {
 
 AllocationResult ReadOnlySpace::AllocateRaw(int size_in_bytes,
                                             AllocationAlignment alignment) {
-  return USE_ALLOCATION_ALIGNMENT_BOOL && alignment != kTaggedAligned
+  AllocationResult result =
+      USE_ALLOCATION_ALIGNMENT_BOOL && alignment != kTaggedAligned
           ? AllocateRawAligned(size_in_bytes, alignment)
           : AllocateRawUnaligned(size_in_bytes);
+  HeapObject heap_obj;
+  if (result.To(&heap_obj)) {
+    DCHECK(heap()->marking_state()->IsBlack(heap_obj));
+  }
+  return result;
 }
 
 size_t ReadOnlyPage::ShrinkToHighWaterMark() {

src/objects/heap-object.h

@@ -95,8 +95,6 @@ class HeapObject : public Object {
 
   V8_INLINE bool InSharedWritableHeap() const;
 
-  V8_INLINE bool InReadOnlySpace() const;
-
 #define IS_TYPE_FUNCTION_DECL(Type) \
   V8_INLINE bool Is##Type() const;  \
   V8_INLINE bool Is##Type(PtrComprCageBase cage_base) const;

src/objects/objects-inl.h

@@ -207,8 +207,6 @@ bool HeapObject::InSharedWritableHeap() const {
   return BasicMemoryChunk::FromHeapObject(*this)->InSharedHeap();
 }
 
-bool HeapObject::InReadOnlySpace() const { return IsReadOnlyHeapObject(*this); }
-
 bool HeapObject::IsJSObjectThatCanBeTrackedAsPrototype() const {
   // Do not optimize objects in the shared heap because it is not
   // threadsafe. Objects in the shared heap have fixed layouts and their maps

test/cctest/heap/test-concurrent-marking.cc

@@ -26,11 +26,6 @@ void PublishSegment(MarkingWorklist& worklist, HeapObject object) {
   local.Publish();
 }
 
-HeapObject ObjectForTesting(i::Isolate* isolate) {
-  return HeapObject::cast(
-      isolate->roots_table().slot(RootIndex::kFirstStrongRoot).load(isolate));
-}
-
 TEST(ConcurrentMarking) {
   if (!i::v8_flags.concurrent_marking) return;
   CcTest::InitializeVM();
@@ -47,7 +42,7 @@ TEST(ConcurrentMarking) {
       new ConcurrentMarking(heap, &weak_objects);
   MarkCompactCollector* collector = CcTest::heap()->mark_compact_collector();
   PublishSegment(*collector->marking_worklists()->shared(),
-                 ObjectForTesting(heap->isolate()));
+                 ReadOnlyRoots(heap).undefined_value());
   concurrent_marking->ScheduleJob(GarbageCollector::MARK_COMPACTOR);
   concurrent_marking->Join();
   delete concurrent_marking;
@@ -69,11 +64,11 @@ TEST(ConcurrentMarkingReschedule) {
       new ConcurrentMarking(heap, &weak_objects);
   MarkCompactCollector* collector = CcTest::heap()->mark_compact_collector();
   PublishSegment(*collector->marking_worklists()->shared(),
-                 ObjectForTesting(heap->isolate()));
+                 ReadOnlyRoots(heap).undefined_value());
   concurrent_marking->ScheduleJob(GarbageCollector::MARK_COMPACTOR);
   concurrent_marking->Join();
   PublishSegment(*collector->marking_worklists()->shared(),
-                 ObjectForTesting(heap->isolate()));
+                 ReadOnlyRoots(heap).undefined_value());
   concurrent_marking->RescheduleJobIfNeeded(GarbageCollector::MARK_COMPACTOR);
   concurrent_marking->Join();
   delete concurrent_marking;
@@ -96,12 +91,12 @@ TEST(ConcurrentMarkingPreemptAndReschedule) {
   MarkCompactCollector* collector = CcTest::heap()->mark_compact_collector();
   for (int i = 0; i < 5000; i++)
     PublishSegment(*collector->marking_worklists()->shared(),
-                   ObjectForTesting(heap->isolate()));
+                   ReadOnlyRoots(heap).undefined_value());
   concurrent_marking->ScheduleJob(GarbageCollector::MARK_COMPACTOR);
   concurrent_marking->Pause();
   for (int i = 0; i < 5000; i++)
     PublishSegment(*collector->marking_worklists()->shared(),
-                   ObjectForTesting(heap->isolate()));
+                   ReadOnlyRoots(heap).undefined_value());
   concurrent_marking->RescheduleJobIfNeeded(GarbageCollector::MARK_COMPACTOR);
   concurrent_marking->Join();
   delete concurrent_marking;

test/cctest/heap/test-heap.cc

@@ -5811,7 +5811,7 @@ TEST(Regress598319) {
   // progress bar, we would fail here.
   for (int i = 0; i < arr.get().length(); i++) {
     HeapObject arr_value = HeapObject::cast(arr.get().get(i));
-    CHECK(arr_value.InReadOnlySpace() || marking_state->IsBlack(arr_value));
+    CHECK(marking_state->IsBlack(arr_value));
   }
 }
 

test/unittests/heap/marking-worklist-unittest.cc

@@ -22,10 +22,7 @@ TEST_F(MarkingWorklistTest, PushPop) {
   MarkingWorklists holder;
   MarkingWorklists::Local worklists(&holder);
   HeapObject pushed_object =
-      HeapObject::cast(i_isolate()
-                           ->roots_table()
-                           .slot(RootIndex::kFirstStrongRoot)
-                           .load(i_isolate()));
+      ReadOnlyRoots(i_isolate()->heap()).undefined_value();
   worklists.Push(pushed_object);
   HeapObject popped_object;
   EXPECT_TRUE(worklists.Pop(&popped_object));
@@ -36,10 +33,7 @@ TEST_F(MarkingWorklistTest, PushPopOnHold) {
   MarkingWorklists holder;
   MarkingWorklists::Local worklists(&holder);
   HeapObject pushed_object =
-      HeapObject::cast(i_isolate()
-                           ->roots_table()
-                           .slot(RootIndex::kFirstStrongRoot)
-                           .load(i_isolate()));
+      ReadOnlyRoots(i_isolate()->heap()).undefined_value();
   worklists.PushOnHold(pushed_object);
   HeapObject popped_object;
   EXPECT_TRUE(worklists.PopOnHold(&popped_object));
@@ -51,10 +45,7 @@ TEST_F(MarkingWorklistTest, MergeOnHold) {
   MarkingWorklists::Local main_worklists(&holder);
   MarkingWorklists::Local worker_worklists(&holder);
   HeapObject pushed_object =
-      HeapObject::cast(i_isolate()
-                           ->roots_table()
-                           .slot(RootIndex::kFirstStrongRoot)
-                           .load(i_isolate()));
+      ReadOnlyRoots(i_isolate()->heap()).undefined_value();
   worker_worklists.PushOnHold(pushed_object);
   worker_worklists.Publish();
   main_worklists.MergeOnHold();
@@ -68,10 +59,7 @@ TEST_F(MarkingWorklistTest, ShareWorkIfGlobalPoolIsEmpty) {
   MarkingWorklists::Local main_worklists(&holder);
   MarkingWorklists::Local worker_worklists(&holder);
   HeapObject pushed_object =
-      HeapObject::cast(i_isolate()
-                           ->roots_table()
-                           .slot(RootIndex::kFirstStrongRoot)
-                           .load(i_isolate()));
+      ReadOnlyRoots(i_isolate()->heap()).undefined_value();
   main_worklists.Push(pushed_object);
   main_worklists.ShareWork();
   HeapObject popped_object;
@@ -85,10 +73,7 @@ TEST_F(MarkingWorklistTest, ContextWorklistsPushPop) {
   holder.CreateContextWorklists({context});
   MarkingWorklists::Local worklists(&holder);
   HeapObject pushed_object =
-      HeapObject::cast(i_isolate()
-                           ->roots_table()
-                           .slot(RootIndex::kFirstStrongRoot)
-                           .load(i_isolate()));
+      ReadOnlyRoots(i_isolate()->heap()).undefined_value();
   worklists.SwitchToContext(context);
   worklists.Push(pushed_object);
   worklists.SwitchToSharedForTesting();
@@ -104,10 +89,7 @@ TEST_F(MarkingWorklistTest, ContextWorklistsEmpty) {
   holder.CreateContextWorklists({context});
   MarkingWorklists::Local worklists(&holder);
   HeapObject pushed_object =
-      HeapObject::cast(i_isolate()
-                           ->roots_table()
-                           .slot(RootIndex::kFirstStrongRoot)
-                           .load(i_isolate()));
+      ReadOnlyRoots(i_isolate()->heap()).undefined_value();
   worklists.SwitchToContext(context);
   worklists.Push(pushed_object);
   EXPECT_FALSE(worklists.IsEmpty());
@@ -128,10 +110,7 @@ TEST_F(MarkingWorklistTest, ContextWorklistCrossTask) {
   MarkingWorklists::Local main_worklists(&holder);
   MarkingWorklists::Local worker_worklists(&holder);
   HeapObject pushed_object =
-      HeapObject::cast(i_isolate()
-                           ->roots_table()
-                           .slot(RootIndex::kFirstStrongRoot)
-                           .load(i_isolate()));
+      ReadOnlyRoots(i_isolate()->heap()).undefined_value();
   main_worklists.SwitchToContext(context1);
   main_worklists.Push(pushed_object);
   main_worklists.ShareWork();