[heap] Introduce old-to-new invalidation set

Introduce list of invalidated objects for old-to-new slots. Objects
are registered as invalidated in NotifyObjectLayoutChange, however
no slots are filtered right now. Slots are still deleted, so all
recorded slots are valid.

Always treat old-to-new slots in free space as valid. With
old-to-new slots, invalid ones are still cleared.

Bug: v8:9454
Change-Id: I18c65fdaccdb651f4124d36861105ce4e8af0fad
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1768357Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#63396}

src/heap/heap.cc

@@ -1108,6 +1108,15 @@ void Heap::GarbageCollectionEpilogue() {
   AllowHeapAllocation for_the_rest_of_the_epilogue;
 
 #ifdef DEBUG
+  // Old-to-new slot sets must be empty after each collection.
+  for (SpaceIterator it(this); it.HasNext();) {
+    Space* space = it.Next();
+
+    for (MemoryChunk* chunk = space->first_page(); chunk != space->last_page();
+         chunk = chunk->list_node().next())
+      DCHECK_NULL(chunk->invalidated_slots<OLD_TO_NEW>());
+  }
+
   if (FLAG_print_global_handles) isolate_->global_handles()->Print();
   if (FLAG_print_handles) PrintHandles();
   if (FLAG_gc_verbose) Print();
@@ -2998,13 +3007,20 @@ FixedArrayBase Heap::LeftTrimFixedArray(FixedArrayBase object,
   FixedArrayBase new_object =
       FixedArrayBase::cast(HeapObject::FromAddress(new_start));
 
+#ifdef DEBUG
+  if (MayContainRecordedSlots(object)) {
+    MemoryChunk* chunk = MemoryChunk::FromHeapObject(object);
+    DCHECK(!chunk->RegisteredObjectWithInvalidatedSlots<OLD_TO_NEW>(object));
+  }
+#endif
+
   // Handle invalidated old-to-old slots.
   if (incremental_marking()->IsCompacting() &&
       MayContainRecordedSlots(new_object)) {
     // If the array was right-trimmed before, then it is registered in
     // the invalidated_slots.
     MemoryChunk::FromHeapObject(new_object)
-        ->MoveObjectWithInvalidatedSlots(filler, new_object);
+        ->MoveObjectWithInvalidatedSlots<OLD_TO_OLD>(filler, new_object);
     // We have to clear slots in the free space to avoid stale old-to-old slots.
     // Note we cannot use ClearFreedMemoryMode of CreateFillerObjectAt because
     // we need pointer granularity writes to avoid race with the concurrent
@@ -3083,6 +3099,13 @@ void Heap::CreateFillerForArray(T object, int elements_to_trim,
   Address old_end = object.address() + old_size;
   Address new_end = old_end - bytes_to_trim;
 
+#ifdef DEBUG
+  if (MayContainRecordedSlots(object)) {
+    MemoryChunk* chunk = MemoryChunk::FromHeapObject(object);
+    DCHECK(!chunk->RegisteredObjectWithInvalidatedSlots<OLD_TO_NEW>(object));
+  }
+#endif
+
   // Register the array as an object with invalidated old-to-old slots. We
   // cannot use NotifyObjectLayoutChange as it would mark the array black,
   // which is not safe for left-trimming because left-trimming re-pushes
@@ -3092,8 +3115,8 @@ void Heap::CreateFillerForArray(T object, int elements_to_trim,
     // Ensure that the object survives because the InvalidatedSlotsFilter will
     // compute its size from its map during pointers updating phase.
     incremental_marking()->WhiteToGreyAndPush(object);
-    MemoryChunk::FromHeapObject(object)->RegisterObjectWithInvalidatedSlots(
-        object, old_size);
+    MemoryChunk* chunk = MemoryChunk::FromHeapObject(object);
+    chunk->RegisterObjectWithInvalidatedSlots<OLD_TO_OLD>(object, old_size);
   }
 
   // Technically in new space this write might be omitted (except for
@@ -3385,9 +3408,13 @@ void Heap::NotifyObjectLayoutChange(HeapObject object, int size,
     incremental_marking()->MarkBlackAndVisitObjectDueToLayoutChange(object);
     if (incremental_marking()->IsCompacting() &&
         MayContainRecordedSlots(object)) {
-      MemoryChunk::FromHeapObject(object)->RegisterObjectWithInvalidatedSlots(
-          object, size);
+      MemoryChunk::FromHeapObject(object)
+          ->RegisterObjectWithInvalidatedSlots<OLD_TO_OLD>(object, size);
+    }
   }
+  if (MayContainRecordedSlots(object)) {
+    MemoryChunk::FromHeapObject(object)
+        ->RegisterObjectWithInvalidatedSlots<OLD_TO_NEW>(object, size);
   }
 #ifdef VERIFY_HEAP
   if (FLAG_verify_heap) {
@@ -5537,7 +5564,7 @@ void Heap::VerifyClearedSlot(HeapObject object, ObjectSlot slot) {
   CHECK(!RememberedSet<OLD_TO_NEW>::Contains(page, slot.address()));
   // Old to old slots are filtered with invalidated slots.
   CHECK_IMPLIES(RememberedSet<OLD_TO_OLD>::Contains(page, slot.address()),
-                page->RegisteredObjectWithInvalidatedSlots(object));
+                page->RegisteredObjectWithInvalidatedSlots<OLD_TO_OLD>(object));
 }
 #endif
 

src/heap/invalidated-slots-inl.h

@@ -62,6 +62,53 @@ bool InvalidatedSlotsFilter::IsValid(Address slot) {
   return invalidated_object_.IsValidSlot(invalidated_object_.map(), offset);
 }
 
+void InvalidatedSlotsCleanup::Free(Address free_start, Address free_end) {
+#ifdef DEBUG
+  DCHECK_LT(free_start, free_end);
+  // Free regions should come in increasing order and do not overlap
+  DCHECK_LE(last_free_, free_start);
+  last_free_ = free_start;
+#endif
+
+  if (iterator_ == iterator_end_) return;
+
+  // Ignore invalidated objects before free region
+  while (free_start >= invalidated_end_) {
+    ++iterator_;
+    NextInvalidatedObject();
+  }
+
+  // Loop here: Free region might contain multiple invalidated objects
+  while (free_end > invalidated_start_) {
+    // Case: Free region starts before current invalidated object
+    if (free_start <= invalidated_start_) {
+      CHECK(invalidated_end_ <= free_end);
+      iterator_ = invalidated_slots_->erase(iterator_);
+
+    } else {
+      // Case: Free region starts within current invalidated object
+      // (Can happen for right-trimmed objects)
+      iterator_->second =
+          static_cast<int>(free_start - iterator_->first.address());
+
+      CHECK(free_end >= invalidated_end_);
+      iterator_++;
+    }
+
+    NextInvalidatedObject();
+  }
+}
+
+void InvalidatedSlotsCleanup::NextInvalidatedObject() {
+  if (iterator_ != iterator_end_) {
+    invalidated_start_ = iterator_->first.address();
+    invalidated_end_ = invalidated_start_ + iterator_->second;
+  } else {
+    invalidated_start_ = sentinel_;
+    invalidated_end_ = sentinel_;
+  }
+}
+
 }  // namespace internal
 }  // namespace v8
 

src/heap/invalidated-slots.cc

@@ -8,18 +8,35 @@
 namespace v8 {
 namespace internal {
 
-InvalidatedSlotsFilter::InvalidatedSlotsFilter(MemoryChunk* chunk) {
-  // Adjust slots_in_free_space_are_valid_ if more spaces are added.
-  DCHECK_IMPLIES(chunk->invalidated_slots() != nullptr,
-                 chunk->InOldSpace() || chunk->InLargeObjectSpace());
+InvalidatedSlotsFilter InvalidatedSlotsFilter::OldToOld(MemoryChunk* chunk) {
   // The sweeper removes invalid slots and makes free space available for
   // allocation. Slots for new objects can be recorded in the free space.
   // Note that we cannot simply check for SweepingDone because pages in large
   // object space are not swept but have SweepingDone() == true.
-  slots_in_free_space_are_valid_ = chunk->SweepingDone() && chunk->InOldSpace();
+  bool slots_in_free_space_are_valid =
+      chunk->SweepingDone() && chunk->InOldSpace();
+  return InvalidatedSlotsFilter(chunk, chunk->invalidated_slots<OLD_TO_OLD>(),
+                                slots_in_free_space_are_valid);
+}
+
+InvalidatedSlotsFilter InvalidatedSlotsFilter::OldToNew(MemoryChunk* chunk) {
+  // Always treat these slots as valid for old-to-new for now. Invalid
+  // old-to-new slots are always cleared.
+  bool slots_in_free_space_are_valid = true;
+  return InvalidatedSlotsFilter(chunk, chunk->invalidated_slots<OLD_TO_NEW>(),
+                                slots_in_free_space_are_valid);
+}
+
+InvalidatedSlotsFilter::InvalidatedSlotsFilter(
+    MemoryChunk* chunk, InvalidatedSlots* invalidated_slots,
+    bool slots_in_free_space_are_valid) {
+  // Adjust slots_in_free_space_are_valid_ if more spaces are added.
+  DCHECK_IMPLIES(invalidated_slots != nullptr,
+                 chunk->InOldSpace() || chunk->InLargeObjectSpace());
+
+  slots_in_free_space_are_valid_ = slots_in_free_space_are_valid;
+  invalidated_slots = invalidated_slots ? invalidated_slots : &empty_;
 
-  InvalidatedSlots* invalidated_slots =
-      chunk->invalidated_slots() ? chunk->invalidated_slots() : &empty_;
   iterator_ = invalidated_slots->begin();
   iterator_end_ = invalidated_slots->end();
   sentinel_ = chunk->area_end();
@@ -37,5 +54,33 @@ InvalidatedSlotsFilter::InvalidatedSlotsFilter(MemoryChunk* chunk) {
 #endif
 }
 
+InvalidatedSlotsCleanup InvalidatedSlotsCleanup::OldToNew(MemoryChunk* chunk) {
+  return InvalidatedSlotsCleanup(chunk, chunk->invalidated_slots<OLD_TO_NEW>());
+}
+
+InvalidatedSlotsCleanup InvalidatedSlotsCleanup::NoCleanup(MemoryChunk* chunk) {
+  return InvalidatedSlotsCleanup(chunk, nullptr);
+}
+
+InvalidatedSlotsCleanup::InvalidatedSlotsCleanup(
+    MemoryChunk* chunk, InvalidatedSlots* invalidated_slots) {
+  invalidated_slots_ = invalidated_slots ? invalidated_slots : &empty_;
+  iterator_ = invalidated_slots_->begin();
+  iterator_end_ = invalidated_slots_->end();
+  sentinel_ = chunk->area_end();
+
+  if (iterator_ != iterator_end_) {
+    invalidated_start_ = iterator_->first.address();
+    invalidated_end_ = invalidated_start_ + iterator_->second;
+  } else {
+    invalidated_start_ = sentinel_;
+    invalidated_end_ = sentinel_;
+  }
+
+#ifdef DEBUG
+  last_free_ = chunk->area_start();
+#endif
+}
+
 }  // namespace internal
 }  // namespace v8

src/heap/invalidated-slots.h

@@ -30,7 +30,12 @@ using InvalidatedSlots = std::map<HeapObject, int, Object::Comparer>;
 // n is the number of IsValid queries.
 class V8_EXPORT_PRIVATE InvalidatedSlotsFilter {
  public:
-  explicit InvalidatedSlotsFilter(MemoryChunk* chunk);
+  static InvalidatedSlotsFilter OldToOld(MemoryChunk* chunk);
+  static InvalidatedSlotsFilter OldToNew(MemoryChunk* chunk);
+
+  explicit InvalidatedSlotsFilter(MemoryChunk* chunk,
+                                  InvalidatedSlots* invalidated_slots,
+                                  bool slots_in_free_space_are_valid);
   inline bool IsValid(Address slot);
 
  private:
@@ -48,6 +53,32 @@ class V8_EXPORT_PRIVATE InvalidatedSlotsFilter {
 #endif
 };
 
+class V8_EXPORT_PRIVATE InvalidatedSlotsCleanup {
+ public:
+  static InvalidatedSlotsCleanup OldToNew(MemoryChunk* chunk);
+  static InvalidatedSlotsCleanup NoCleanup(MemoryChunk* chunk);
+
+  explicit InvalidatedSlotsCleanup(MemoryChunk* chunk,
+                                   InvalidatedSlots* invalidated_slots);
+
+  inline void Free(Address free_start, Address free_end);
+
+ private:
+  InvalidatedSlots::iterator iterator_;
+  InvalidatedSlots::iterator iterator_end_;
+  InvalidatedSlots* invalidated_slots_;
+  InvalidatedSlots empty_;
+
+  Address sentinel_;
+  Address invalidated_start_;
+  Address invalidated_end_;
+
+  inline void NextInvalidatedObject();
+#ifdef DEBUG
+  Address last_free_;
+#endif
+};
+
 }  // namespace internal
 }  // namespace v8
 

src/heap/mark-compact.cc

@@ -2689,7 +2689,8 @@ void MarkCompactCollector::EvacuateEpilogue() {
   for (Page* p : *heap()->old_space()) {
     DCHECK_NULL((p->slot_set<OLD_TO_OLD, AccessMode::ATOMIC>()));
     DCHECK_NULL((p->typed_slot_set<OLD_TO_OLD, AccessMode::ATOMIC>()));
-    DCHECK_NULL(p->invalidated_slots());
+    DCHECK_NULL(p->invalidated_slots<OLD_TO_OLD>());
+    DCHECK_NULL(p->invalidated_slots<OLD_TO_NEW>());
   }
 #endif
 }
@@ -3410,16 +3411,32 @@ class RememberedSetUpdatingItem : public UpdatingItem {
 
   void UpdateUntypedPointers() {
     if (chunk_->slot_set<OLD_TO_NEW, AccessMode::NON_ATOMIC>() != nullptr) {
+      InvalidatedSlotsFilter filter = InvalidatedSlotsFilter::OldToNew(chunk_);
       RememberedSet<OLD_TO_NEW>::Iterate(
           chunk_,
-          [this](MaybeObjectSlot slot) {
+          [this, &filter](MaybeObjectSlot slot) {
+            if (!filter.IsValid(slot.address())) return REMOVE_SLOT;
             return CheckAndUpdateOldToNewSlot(slot);
           },
           SlotSet::PREFREE_EMPTY_BUCKETS);
     }
+
+    if (chunk_->invalidated_slots<OLD_TO_NEW>() != nullptr) {
+#ifdef DEBUG
+      for (auto object_size : *chunk_->invalidated_slots<OLD_TO_NEW>()) {
+        HeapObject object = object_size.first;
+        int size = object_size.second;
+        DCHECK_LE(object.SizeFromMap(object.map()), size);
+      }
+#endif
+      // The invalidated slots are not needed after old-to-new slots were
+      // processed.
+      chunk_->ReleaseInvalidatedSlots<OLD_TO_NEW>();
+    }
+
     if ((updating_mode_ == RememberedSetUpdatingMode::ALL) &&
         (chunk_->slot_set<OLD_TO_OLD, AccessMode::NON_ATOMIC>() != nullptr)) {
-      InvalidatedSlotsFilter filter(chunk_);
+      InvalidatedSlotsFilter filter = InvalidatedSlotsFilter::OldToOld(chunk_);
       RememberedSet<OLD_TO_OLD>::Iterate(
           chunk_,
           [&filter](MaybeObjectSlot slot) {
@@ -3429,9 +3446,9 @@ class RememberedSetUpdatingItem : public UpdatingItem {
           SlotSet::PREFREE_EMPTY_BUCKETS);
     }
     if ((updating_mode_ == RememberedSetUpdatingMode::ALL) &&
-        chunk_->invalidated_slots() != nullptr) {
+        chunk_->invalidated_slots<OLD_TO_OLD>() != nullptr) {
 #ifdef DEBUG
-      for (auto object_size : *chunk_->invalidated_slots()) {
+      for (auto object_size : *chunk_->invalidated_slots<OLD_TO_OLD>()) {
         HeapObject object = object_size.first;
         int size = object_size.second;
         DCHECK_LE(object.SizeFromMap(object.map()), size);
@@ -3439,7 +3456,7 @@ class RememberedSetUpdatingItem : public UpdatingItem {
 #endif
       // The invalidated slots are not needed after old-to-old slots were
       // processsed.
-      chunk_->ReleaseInvalidatedSlots();
+      chunk_->ReleaseInvalidatedSlots<OLD_TO_OLD>();
     }
   }
 
@@ -3553,13 +3570,17 @@ int MarkCompactCollectorBase::CollectRememberedSetUpdatingItems(
     const bool contains_old_to_new_slots =
         chunk->slot_set<OLD_TO_NEW>() != nullptr ||
         chunk->typed_slot_set<OLD_TO_NEW>() != nullptr;
-    const bool contains_invalidated_slots =
-        chunk->invalidated_slots() != nullptr;
+    const bool contains_old_to_old_invalidated_slots =
+        chunk->invalidated_slots<OLD_TO_OLD>() != nullptr;
+    const bool contains_old_to_new_invalidated_slots =
+        chunk->invalidated_slots<OLD_TO_NEW>() != nullptr;
     if (!contains_old_to_new_slots && !contains_old_to_old_slots &&
-        !contains_invalidated_slots)
+        !contains_old_to_old_invalidated_slots &&
+        !contains_old_to_new_invalidated_slots)
       continue;
     if (mode == RememberedSetUpdatingMode::ALL || contains_old_to_new_slots ||
-        contains_invalidated_slots) {
+        contains_old_to_old_invalidated_slots ||
+        contains_old_to_new_invalidated_slots) {
       job->AddItem(CreateRememberedSetUpdatingItem(chunk, mode));
       pages++;
     }
@@ -4636,9 +4657,11 @@ class PageMarkingItem : public MarkingItem {
   inline Heap* heap() { return chunk_->heap(); }
 
   void MarkUntypedPointers(YoungGenerationMarkingTask* task) {
+    InvalidatedSlotsFilter filter = InvalidatedSlotsFilter::OldToNew(chunk_);
     RememberedSet<OLD_TO_NEW>::Iterate(
         chunk_,
-        [this, task](MaybeObjectSlot slot) {
+        [this, task, &filter](MaybeObjectSlot slot) {
+          if (!filter.IsValid(slot.address())) return REMOVE_SLOT;
           return CheckAndMarkObject(task, slot);
         },
         SlotSet::PREFREE_EMPTY_BUCKETS);

src/heap/remembered-set.h

@@ -122,7 +122,7 @@ class RememberedSet : public AllStatic {
       SlotSet* slots = chunk->slot_set<type>();
       TypedSlotSet* typed_slots = chunk->typed_slot_set<type>();
       if (slots != nullptr || typed_slots != nullptr ||
-          chunk->invalidated_slots() != nullptr) {
+          chunk->invalidated_slots<type>() != nullptr) {
         callback(chunk);
       }
     }
@@ -256,7 +256,7 @@ class RememberedSet : public AllStatic {
     while ((chunk = it.next()) != nullptr) {
       chunk->ReleaseSlotSet<OLD_TO_OLD>();
       chunk->ReleaseTypedSlotSet<OLD_TO_OLD>();
-      chunk->ReleaseInvalidatedSlots();
+      chunk->ReleaseInvalidatedSlots<OLD_TO_OLD>();
     }
   }
 

src/heap/scavenger.cc

@@ -8,6 +8,7 @@
 #include "src/heap/barrier.h"
 #include "src/heap/gc-tracer.h"
 #include "src/heap/heap-inl.h"
+#include "src/heap/invalidated-slots-inl.h"
 #include "src/heap/item-parallel-job.h"
 #include "src/heap/mark-compact-inl.h"
 #include "src/heap/objects-visiting-inl.h"
@@ -431,12 +432,28 @@ void Scavenger::AddPageToSweeperIfNecessary(MemoryChunk* page) {
 
 void Scavenger::ScavengePage(MemoryChunk* page) {
   CodePageMemoryModificationScope memory_modification_scope(page);
+  InvalidatedSlotsFilter filter = InvalidatedSlotsFilter::OldToNew(page);
   RememberedSet<OLD_TO_NEW>::Iterate(
       page,
-      [this](MaybeObjectSlot addr) {
+      [this, &filter](MaybeObjectSlot addr) {
+        if (!filter.IsValid(addr.address())) return REMOVE_SLOT;
         return CheckAndScavengeObject(heap_, addr);
       },
       SlotSet::KEEP_EMPTY_BUCKETS);
+
+  if (page->invalidated_slots<OLD_TO_NEW>() != nullptr) {
+#ifdef DEBUG
+    for (auto object_size : *page->invalidated_slots<OLD_TO_NEW>()) {
+      HeapObject object = object_size.first;
+      int size = object_size.second;
+      DCHECK_LE(object.SizeFromMap(object.map()), size);
+    }
+#endif
+    // The invalidated slots are not needed after old-to-new slots were
+    // processed.
+    page->ReleaseInvalidatedSlots<OLD_TO_NEW>();
+  }
+
   RememberedSet<OLD_TO_NEW>::IterateTyped(
       page, [=](SlotType type, Address addr) {
         return UpdateTypedSlotHelper::UpdateTypedSlot(

src/heap/spaces.cc

@@ -703,7 +703,8 @@ MemoryChunk* MemoryChunk::Initialize(Heap* heap, Address base, size_t size,
                                        nullptr);
   base::AsAtomicPointer::Release_Store(&chunk->typed_slot_set_[OLD_TO_OLD],
                                        nullptr);
-  chunk->invalidated_slots_ = nullptr;
+  chunk->invalidated_slots_[OLD_TO_NEW] = nullptr;
+  chunk->invalidated_slots_[OLD_TO_OLD] = nullptr;
   chunk->progress_bar_ = 0;
   chunk->high_water_mark_ = static_cast<intptr_t>(area_start - base);
   chunk->set_concurrent_sweeping_state(kSweepingDone);
@@ -1379,7 +1380,8 @@ void MemoryChunk::ReleaseAllocatedMemoryNeededForWritableChunk() {
   ReleaseSlotSet<OLD_TO_OLD>();
   ReleaseTypedSlotSet<OLD_TO_NEW>();
   ReleaseTypedSlotSet<OLD_TO_OLD>();
-  ReleaseInvalidatedSlots();
+  ReleaseInvalidatedSlots<OLD_TO_NEW>();
+  ReleaseInvalidatedSlots<OLD_TO_OLD>();
 
   if (local_tracker_ != nullptr) ReleaseLocalTracker();
   if (young_generation_bitmap_ != nullptr) ReleaseYoungGenerationBitmap();
@@ -1461,53 +1463,107 @@ void MemoryChunk::ReleaseTypedSlotSet() {
   }
 }
 
+template InvalidatedSlots* MemoryChunk::AllocateInvalidatedSlots<OLD_TO_NEW>();
+template InvalidatedSlots* MemoryChunk::AllocateInvalidatedSlots<OLD_TO_OLD>();
+
+template <RememberedSetType type>
 InvalidatedSlots* MemoryChunk::AllocateInvalidatedSlots() {
-  DCHECK_NULL(invalidated_slots_);
-  invalidated_slots_ = new InvalidatedSlots();
-  return invalidated_slots_;
+  DCHECK_NULL(invalidated_slots_[type]);
+  invalidated_slots_[type] = new InvalidatedSlots();
+  return invalidated_slots_[type];
 }
 
+template void MemoryChunk::ReleaseInvalidatedSlots<OLD_TO_NEW>();
+template void MemoryChunk::ReleaseInvalidatedSlots<OLD_TO_OLD>();
+
+template <RememberedSetType type>
 void MemoryChunk::ReleaseInvalidatedSlots() {
-  if (invalidated_slots_) {
-    delete invalidated_slots_;
-    invalidated_slots_ = nullptr;
+  if (invalidated_slots_[type]) {
+    delete invalidated_slots_[type];
+    invalidated_slots_[type] = nullptr;
   }
 }
 
+template V8_EXPORT_PRIVATE void
+MemoryChunk::RegisterObjectWithInvalidatedSlots<OLD_TO_NEW>(HeapObject object,
+                                                            int size);
+template V8_EXPORT_PRIVATE void
+MemoryChunk::RegisterObjectWithInvalidatedSlots<OLD_TO_OLD>(HeapObject object,
+                                                            int size);
+
+template <RememberedSetType type>
 void MemoryChunk::RegisterObjectWithInvalidatedSlots(HeapObject object,
                                                      int size) {
-  if (!ShouldSkipEvacuationSlotRecording()) {
-    if (invalidated_slots() == nullptr) {
-      AllocateInvalidatedSlots();
+  bool skip_slot_recording;
+
+  if (type == OLD_TO_NEW) {
+    skip_slot_recording = InYoungGeneration();
+  } else {
+    skip_slot_recording = ShouldSkipEvacuationSlotRecording();
+  }
+
+  if (skip_slot_recording) {
+    return;
+  }
+
+  if (invalidated_slots<type>() == nullptr) {
+    AllocateInvalidatedSlots<type>();
+  }
+
+  InvalidatedSlots* invalidated_slots = this->invalidated_slots<type>();
+  InvalidatedSlots::iterator it = invalidated_slots->lower_bound(object);
+
+  if (it != invalidated_slots->end() && it->first == object) {
+    // object was already inserted
+    CHECK_LE(size, it->second);
+    return;
+  }
+
+  it = invalidated_slots->insert(it, std::make_pair(object, size));
+
+  // prevent overlapping invalidated objects for old-to-new.
+  if (type == OLD_TO_NEW && it != invalidated_slots->begin()) {
+    HeapObject pred = (--it)->first;
+    int pred_size = it->second;
+    DCHECK_LT(pred.address(), object.address());
+
+    if (pred.address() + pred_size > object.address()) {
+      it->second = static_cast<int>(object.address() - pred.address());
     }
-    int old_size = (*invalidated_slots())[object];
-    (*invalidated_slots())[object] = std::max(old_size, size);
   }
 }
 
+template bool MemoryChunk::RegisteredObjectWithInvalidatedSlots<OLD_TO_NEW>(
+    HeapObject object);
+template bool MemoryChunk::RegisteredObjectWithInvalidatedSlots<OLD_TO_OLD>(
+    HeapObject object);
+
+template <RememberedSetType type>
 bool MemoryChunk::RegisteredObjectWithInvalidatedSlots(HeapObject object) {
-  if (ShouldSkipEvacuationSlotRecording()) {
-    // Invalidated slots do not matter if we are not recording slots.
-    return true;
-  }
-  if (invalidated_slots() == nullptr) {
+  if (invalidated_slots<type>() == nullptr) {
     return false;
   }
-  return invalidated_slots()->find(object) != invalidated_slots()->end();
+  return invalidated_slots<type>()->find(object) !=
+         invalidated_slots<type>()->end();
 }
 
+template void MemoryChunk::MoveObjectWithInvalidatedSlots<OLD_TO_OLD>(
+    HeapObject old_start, HeapObject new_start);
+
+template <RememberedSetType type>
 void MemoryChunk::MoveObjectWithInvalidatedSlots(HeapObject old_start,
                                                  HeapObject new_start) {
   DCHECK_LT(old_start, new_start);
   DCHECK_EQ(MemoryChunk::FromHeapObject(old_start),
             MemoryChunk::FromHeapObject(new_start));
-  if (!ShouldSkipEvacuationSlotRecording() && invalidated_slots()) {
-    auto it = invalidated_slots()->find(old_start);
-    if (it != invalidated_slots()->end()) {
+  static_assert(type == OLD_TO_OLD, "only use this for old-to-old slots");
+  if (!ShouldSkipEvacuationSlotRecording() && invalidated_slots<type>()) {
+    auto it = invalidated_slots<type>()->find(old_start);
+    if (it != invalidated_slots<type>()->end()) {
       int old_size = it->second;
       int delta = static_cast<int>(new_start.address() - old_start.address());
-      invalidated_slots()->erase(it);
-      (*invalidated_slots())[new_start] = old_size - delta;
+      invalidated_slots<type>()->erase(it);
+      (*invalidated_slots<type>())[new_start] = old_size - delta;
     }
   }
 }
@@ -3693,9 +3749,17 @@ bool PagedSpace::RawSlowRefillLinearAllocationArea(int size_in_bytes,
             static_cast<size_t>(size_in_bytes), origin))
       return true;
 
+    // Cleanup invalidated old-to-new refs for compaction space in the
+    // final atomic pause.
+    Sweeper::FreeSpaceMayContainInvalidatedSlots
+        invalidated_slots_in_free_space =
+            is_local() ? Sweeper::FreeSpaceMayContainInvalidatedSlots::kYes
+                       : Sweeper::FreeSpaceMayContainInvalidatedSlots::kNo;
+
     // If sweeping is still in progress try to sweep pages.
     int max_freed = collector->sweeper()->ParallelSweepSpace(
-        identity(), size_in_bytes, kMaxPagesToSweep);
+        identity(), size_in_bytes, kMaxPagesToSweep,
+        invalidated_slots_in_free_space);
     RefillFreeList();
     if (max_freed >= size_in_bytes) {
       if (RefillLinearAllocationAreaFromFreeList(

src/heap/spaces.h

@@ -636,7 +636,8 @@ class MemoryChunk : public BasicMemoryChunk {
       + kSystemPointerSize * NUMBER_OF_REMEMBERED_SET_TYPES  // SlotSet* array
       + kSystemPointerSize *
             NUMBER_OF_REMEMBERED_SET_TYPES  // TypedSlotSet* array
-      + kSystemPointerSize  // InvalidatedSlots* invalidated_slots_
+      + kSystemPointerSize *
+            NUMBER_OF_REMEMBERED_SET_TYPES  // InvalidatedSlots* array
       + kSystemPointerSize  // std::atomic<intptr_t> high_water_mark_
       + kSystemPointerSize  // base::Mutex* mutex_
       + kSystemPointerSize  // std::atomic<ConcurrentSweepingState>
@@ -722,7 +723,7 @@ class MemoryChunk : public BasicMemoryChunk {
   template <RememberedSetType type>
   bool ContainsSlots() {
     return slot_set<type>() != nullptr || typed_slot_set<type>() != nullptr ||
-           invalidated_slots() != nullptr;
+           invalidated_slots<type>() != nullptr;
   }
 
   template <RememberedSetType type, AccessMode access_mode = AccessMode::ATOMIC>
@@ -750,15 +751,23 @@ class MemoryChunk : public BasicMemoryChunk {
   template <RememberedSetType type>
   void ReleaseTypedSlotSet();
 
+  template <RememberedSetType type>
   InvalidatedSlots* AllocateInvalidatedSlots();
+  template <RememberedSetType type>
   void ReleaseInvalidatedSlots();
+  template <RememberedSetType type>
   V8_EXPORT_PRIVATE void RegisterObjectWithInvalidatedSlots(HeapObject object,
                                                             int size);
   // Updates invalidated_slots after array left-trimming.
+  template <RememberedSetType type>
   void MoveObjectWithInvalidatedSlots(HeapObject old_start,
                                       HeapObject new_start);
+  template <RememberedSetType type>
   bool RegisteredObjectWithInvalidatedSlots(HeapObject object);
-  InvalidatedSlots* invalidated_slots() { return invalidated_slots_; }
+  template <RememberedSetType type>
+  InvalidatedSlots* invalidated_slots() {
+    return invalidated_slots_[type];
+  }
 
   void ReleaseLocalTracker();
 
@@ -934,7 +943,7 @@ class MemoryChunk : public BasicMemoryChunk {
   // is ceil(size() / kPageSize).
   SlotSet* slot_set_[NUMBER_OF_REMEMBERED_SET_TYPES];
   TypedSlotSet* typed_slot_set_[NUMBER_OF_REMEMBERED_SET_TYPES];
-  InvalidatedSlots* invalidated_slots_;
+  InvalidatedSlots* invalidated_slots_[NUMBER_OF_REMEMBERED_SET_TYPES];
 
   // Assuming the initial allocation on a page is sequential,
   // count highest number of bytes ever allocated on the page.

src/heap/sweeper.cc

@@ -8,6 +8,7 @@
 #include "src/execution/vm-state-inl.h"
 #include "src/heap/array-buffer-tracker-inl.h"
 #include "src/heap/gc-tracer.h"
+#include "src/heap/invalidated-slots-inl.h"
 #include "src/heap/mark-compact-inl.h"
 #include "src/heap/remembered-set.h"
 #include "src/objects/objects-inl.h"
@@ -250,8 +251,10 @@ void Sweeper::EnsureCompleted() {
 
 bool Sweeper::AreSweeperTasksRunning() { return num_sweeping_tasks_ != 0; }
 
-int Sweeper::RawSweep(Page* p, FreeListRebuildingMode free_list_mode,
-                      FreeSpaceTreatmentMode free_space_mode) {
+int Sweeper::RawSweep(
+    Page* p, FreeListRebuildingMode free_list_mode,
+    FreeSpaceTreatmentMode free_space_mode,
+    FreeSpaceMayContainInvalidatedSlots invalidated_slots_in_free_space) {
   Space* space = p->owner();
   DCHECK_NOT_NULL(space);
   DCHECK(free_list_mode == IGNORE_FREE_LIST || space->identity() == OLD_SPACE ||
@@ -274,6 +277,15 @@ int Sweeper::RawSweep(Page* p, FreeListRebuildingMode free_list_mode,
   ArrayBufferTracker::FreeDead(p, marking_state_);
 
   Address free_start = p->area_start();
+  InvalidatedSlotsCleanup old_to_new_cleanup =
+      InvalidatedSlotsCleanup::NoCleanup(p);
+
+  // Clean invalidated slots during the final atomic pause. After resuming
+  // execution this isn't necessary, invalid old-to-new refs were already
+  // removed by mark compact's update pointers phase.
+  if (invalidated_slots_in_free_space ==
+      FreeSpaceMayContainInvalidatedSlots::kYes)
+    old_to_new_cleanup = InvalidatedSlotsCleanup::OldToNew(p);
 
   intptr_t live_bytes = 0;
   intptr_t freed_bytes = 0;
@@ -318,6 +330,8 @@ int Sweeper::RawSweep(Page* p, FreeListRebuildingMode free_list_mode,
             static_cast<uint32_t>(free_start - p->address()),
             static_cast<uint32_t>(free_end - p->address())));
       }
+
+      old_to_new_cleanup.Free(free_start, free_end);
     }
     Map map = object.synchronized_map();
     int size = object.SizeFromMap(map);
@@ -350,6 +364,8 @@ int Sweeper::RawSweep(Page* p, FreeListRebuildingMode free_list_mode,
           static_cast<uint32_t>(free_start - p->address()),
           static_cast<uint32_t>(p->area_end() - p->address())));
     }
+
+    old_to_new_cleanup.Free(free_start, p->area_end());
   }
 
   // Clear invalid typed slots after collection all free ranges.
@@ -399,13 +415,15 @@ bool Sweeper::SweepSpaceIncrementallyFromTask(AllocationSpace identity) {
   return sweeping_list_[GetSweepSpaceIndex(identity)].empty();
 }
 
-int Sweeper::ParallelSweepSpace(AllocationSpace identity,
-                                int required_freed_bytes, int max_pages) {
+int Sweeper::ParallelSweepSpace(
+    AllocationSpace identity, int required_freed_bytes, int max_pages,
+    FreeSpaceMayContainInvalidatedSlots invalidated_slots_in_free_space) {
   int max_freed = 0;
   int pages_freed = 0;
   Page* page = nullptr;
   while ((page = GetSweepingPageSafe(identity)) != nullptr) {
-    int freed = ParallelSweepPage(page, identity);
+    int freed =
+        ParallelSweepPage(page, identity, invalidated_slots_in_free_space);
     if (page->IsFlagSet(Page::NEVER_ALLOCATE_ON_PAGE)) {
       // Free list of a never-allocate page will be dropped later on.
       continue;
@@ -419,7 +437,9 @@ int Sweeper::ParallelSweepSpace(AllocationSpace identity,
   return max_freed;
 }
 
-int Sweeper::ParallelSweepPage(Page* page, AllocationSpace identity) {
+int Sweeper::ParallelSweepPage(
+    Page* page, AllocationSpace identity,
+    FreeSpaceMayContainInvalidatedSlots invalidated_slots_in_free_space) {
   // Early bailout for pages that are swept outside of the regular sweeping
   // path. This check here avoids taking the lock first, avoiding deadlocks.
   if (page->SweepingDone()) return 0;
@@ -439,7 +459,8 @@ int Sweeper::ParallelSweepPage(Page* page, AllocationSpace identity) {
     page->set_concurrent_sweeping_state(Page::kSweepingInProgress);
     const FreeSpaceTreatmentMode free_space_mode =
         Heap::ShouldZapGarbage() ? ZAP_FREE_SPACE : IGNORE_FREE_SPACE;
-    max_freed = RawSweep(page, REBUILD_FREE_LIST, free_space_mode);
+    max_freed = RawSweep(page, REBUILD_FREE_LIST, free_space_mode,
+                         invalidated_slots_in_free_space);
     DCHECK(page->SweepingDone());
 
     // After finishing sweeping of a page we clean up its remembered set.
@@ -595,7 +616,8 @@ void Sweeper::MakeIterable(Page* page) {
   DCHECK(IsValidIterabilitySpace(page->owner_identity()));
   const FreeSpaceTreatmentMode free_space_mode =
       Heap::ShouldZapGarbage() ? ZAP_FREE_SPACE : IGNORE_FREE_SPACE;
-  RawSweep(page, IGNORE_FREE_LIST, free_space_mode);
+  RawSweep(page, IGNORE_FREE_LIST, free_space_mode,
+           FreeSpaceMayContainInvalidatedSlots::kNo);
 }
 
 }  // namespace internal

src/heap/sweeper.h

@@ -70,12 +70,8 @@ class Sweeper {
   };
 
   enum FreeListRebuildingMode { REBUILD_FREE_LIST, IGNORE_FREE_LIST };
-  enum ClearOldToNewSlotsMode {
-    DO_NOT_CLEAR,
-    CLEAR_REGULAR_SLOTS,
-    CLEAR_TYPED_SLOTS
-  };
   enum AddPageMode { REGULAR, READD_TEMPORARY_REMOVED_PAGE };
+  enum class FreeSpaceMayContainInvalidatedSlots { kYes, kNo };
 
   Sweeper(Heap* heap, MajorNonAtomicMarkingState* marking_state);
 
@@ -83,14 +79,21 @@ class Sweeper {
 
   void AddPage(AllocationSpace space, Page* page, AddPageMode mode);
 
-  int ParallelSweepSpace(AllocationSpace identity, int required_freed_bytes,
-                         int max_pages = 0);
-  int ParallelSweepPage(Page* page, AllocationSpace identity);
+  int ParallelSweepSpace(
+      AllocationSpace identity, int required_freed_bytes, int max_pages = 0,
+      FreeSpaceMayContainInvalidatedSlots invalidated_slots_in_free_space =
+          FreeSpaceMayContainInvalidatedSlots::kNo);
+  int ParallelSweepPage(
+      Page* page, AllocationSpace identity,
+      FreeSpaceMayContainInvalidatedSlots invalidated_slots_in_free_space =
+          FreeSpaceMayContainInvalidatedSlots::kNo);
 
   void ScheduleIncrementalSweepingTask();
 
-  int RawSweep(Page* p, FreeListRebuildingMode free_list_mode,
-               FreeSpaceTreatmentMode free_space_mode);
+  int RawSweep(
+      Page* p, FreeListRebuildingMode free_list_mode,
+      FreeSpaceTreatmentMode free_space_mode,
+      FreeSpaceMayContainInvalidatedSlots invalidated_slots_in_free_space);
 
   // After calling this function sweeping is considered to be in progress
   // and the main thread can sweep lazily, but the background sweeper tasks

test/cctest/heap/heap-tester.h

@@ -19,6 +19,10 @@
   V(CompactionSpaceDivideSinglePage)                      \
   V(InvalidatedSlotsAfterTrimming)                        \
   V(InvalidatedSlotsAllInvalidatedRanges)                 \
+  V(InvalidatedSlotsCleanupEachObject)                    \
+  V(InvalidatedSlotsCleanupFull)                          \
+  V(InvalidatedSlotsCleanupRightTrim)                     \
+  V(InvalidatedSlotsCleanupOverlapRight)                  \
   V(InvalidatedSlotsEvacuationCandidate)                  \
   V(InvalidatedSlotsNoInvalidatedRanges)                  \
   V(InvalidatedSlotsResetObjectRegression)                \

test/cctest/heap/test-invalidated-slots.cc

@@ -44,7 +44,7 @@ Page* HeapTester::AllocateByteArraysOnPage(
       CHECK_EQ(page, Page::FromHeapObject(byte_array));
     }
   }
-  CHECK_NULL(page->invalidated_slots());
+  CHECK_NULL(page->invalidated_slots<OLD_TO_OLD>());
   return page;
 }
 
@@ -53,7 +53,7 @@ HEAP_TEST(InvalidatedSlotsNoInvalidatedRanges) {
   Heap* heap = CcTest::heap();
   std::vector<ByteArray> byte_arrays;
   Page* page = AllocateByteArraysOnPage(heap, &byte_arrays);
-  InvalidatedSlotsFilter filter(page);
+  InvalidatedSlotsFilter filter = InvalidatedSlotsFilter::OldToOld(page);
   for (ByteArray byte_array : byte_arrays) {
     Address start = byte_array.address() + ByteArray::kHeaderSize;
     Address end = byte_array.address() + byte_array.Size();
@@ -70,10 +70,10 @@ HEAP_TEST(InvalidatedSlotsSomeInvalidatedRanges) {
   Page* page = AllocateByteArraysOnPage(heap, &byte_arrays);
   // Register every second byte arrays as invalidated.
   for (size_t i = 0; i < byte_arrays.size(); i += 2) {
-    page->RegisterObjectWithInvalidatedSlots(byte_arrays[i],
+    page->RegisterObjectWithInvalidatedSlots<OLD_TO_OLD>(byte_arrays[i],
                                                          byte_arrays[i].Size());
   }
-  InvalidatedSlotsFilter filter(page);
+  InvalidatedSlotsFilter filter = InvalidatedSlotsFilter::OldToOld(page);
   for (size_t i = 0; i < byte_arrays.size(); i++) {
     ByteArray byte_array = byte_arrays[i];
     Address start = byte_array.address() + ByteArray::kHeaderSize;
@@ -95,10 +95,10 @@ HEAP_TEST(InvalidatedSlotsAllInvalidatedRanges) {
   Page* page = AllocateByteArraysOnPage(heap, &byte_arrays);
   // Register the all byte arrays as invalidated.
   for (size_t i = 0; i < byte_arrays.size(); i++) {
-    page->RegisterObjectWithInvalidatedSlots(byte_arrays[i],
+    page->RegisterObjectWithInvalidatedSlots<OLD_TO_OLD>(byte_arrays[i],
                                                          byte_arrays[i].Size());
   }
-  InvalidatedSlotsFilter filter(page);
+  InvalidatedSlotsFilter filter = InvalidatedSlotsFilter::OldToOld(page);
   for (size_t i = 0; i < byte_arrays.size(); i++) {
     ByteArray byte_array = byte_arrays[i];
     Address start = byte_array.address() + ByteArray::kHeaderSize;
@@ -117,12 +117,12 @@ HEAP_TEST(InvalidatedSlotsAfterTrimming) {
   Page* page = AllocateByteArraysOnPage(heap, &byte_arrays);
   // Register the all byte arrays as invalidated.
   for (size_t i = 0; i < byte_arrays.size(); i++) {
-    page->RegisterObjectWithInvalidatedSlots(byte_arrays[i],
+    page->RegisterObjectWithInvalidatedSlots<OLD_TO_OLD>(byte_arrays[i],
                                                          byte_arrays[i].Size());
   }
   // Trim byte arrays and check that the slots outside the byte arrays are
   // considered invalid if the old space page was swept.
-  InvalidatedSlotsFilter filter(page);
+  InvalidatedSlotsFilter filter = InvalidatedSlotsFilter::OldToOld(page);
   for (size_t i = 0; i < byte_arrays.size(); i++) {
     ByteArray byte_array = byte_arrays[i];
     Address start = byte_array.address() + ByteArray::kHeaderSize;
@@ -145,11 +145,11 @@ HEAP_TEST(InvalidatedSlotsEvacuationCandidate) {
   // This should be no-op because the page is marked as evacuation
   // candidate.
   for (size_t i = 0; i < byte_arrays.size(); i++) {
-    page->RegisterObjectWithInvalidatedSlots(byte_arrays[i],
+    page->RegisterObjectWithInvalidatedSlots<OLD_TO_OLD>(byte_arrays[i],
                                                          byte_arrays[i].Size());
   }
   // All slots must still be valid.
-  InvalidatedSlotsFilter filter(page);
+  InvalidatedSlotsFilter filter = InvalidatedSlotsFilter::OldToOld(page);
   for (size_t i = 0; i < byte_arrays.size(); i++) {
     ByteArray byte_array = byte_arrays[i];
     Address start = byte_array.address() + ByteArray::kHeaderSize;
@@ -169,11 +169,11 @@ HEAP_TEST(InvalidatedSlotsResetObjectRegression) {
   heap->RightTrimFixedArray(byte_arrays[0], byte_arrays[0].length() - 8);
   // Register the all byte arrays as invalidated.
   for (size_t i = 0; i < byte_arrays.size(); i++) {
-    page->RegisterObjectWithInvalidatedSlots(byte_arrays[i],
+    page->RegisterObjectWithInvalidatedSlots<OLD_TO_OLD>(byte_arrays[i],
                                                          byte_arrays[i].Size());
   }
   // All slots must still be invalid.
-  InvalidatedSlotsFilter filter(page);
+  InvalidatedSlotsFilter filter = InvalidatedSlotsFilter::OldToOld(page);
   for (size_t i = 0; i < byte_arrays.size(); i++) {
     ByteArray byte_array = byte_arrays[i];
     Address start = byte_array.address() + ByteArray::kHeaderSize;
@@ -351,6 +351,78 @@ HEAP_TEST(InvalidatedSlotsFastToSlow) {
   CcTest::CollectGarbage(i::OLD_SPACE);
 }
 
+HEAP_TEST(InvalidatedSlotsCleanupFull) {
+  ManualGCScope manual_gc_scope;
+  CcTest::InitializeVM();
+  Heap* heap = CcTest::heap();
+  std::vector<ByteArray> byte_arrays;
+  Page* page = AllocateByteArraysOnPage(heap, &byte_arrays);
+  // Register all byte arrays as invalidated.
+  for (size_t i = 0; i < byte_arrays.size(); i++) {
+    page->RegisterObjectWithInvalidatedSlots<OLD_TO_NEW>(byte_arrays[i],
+                                                         byte_arrays[i].Size());
+  }
+
+  // Mark full page as free
+  InvalidatedSlotsCleanup cleanup = InvalidatedSlotsCleanup::OldToNew(page);
+  cleanup.Free(page->area_start(), page->area_end());
+
+  // After cleanup there should be no invalidated objects on page left
+  CHECK(page->invalidated_slots<OLD_TO_NEW>()->empty());
+}
+
+HEAP_TEST(InvalidatedSlotsCleanupEachObject) {
+  ManualGCScope manual_gc_scope;
+  CcTest::InitializeVM();
+  Heap* heap = CcTest::heap();
+  std::vector<ByteArray> byte_arrays;
+  Page* page = AllocateByteArraysOnPage(heap, &byte_arrays);
+  // Register all byte arrays as invalidated.
+  for (size_t i = 0; i < byte_arrays.size(); i++) {
+    page->RegisterObjectWithInvalidatedSlots<OLD_TO_NEW>(byte_arrays[i],
+                                                         byte_arrays[i].Size());
+  }
+
+  // Mark each object as free on page
+  InvalidatedSlotsCleanup cleanup = InvalidatedSlotsCleanup::OldToNew(page);
+
+  for (size_t i = 0; i < byte_arrays.size(); i++) {
+    Address free_start = byte_arrays[i].address();
+    Address free_end = free_start + byte_arrays[i].Size();
+    cleanup.Free(free_start, free_end);
+  }
+
+  // After cleanup there should be no invalidated objects on page left
+  CHECK(page->invalidated_slots<OLD_TO_NEW>()->empty());
+}
+
+HEAP_TEST(InvalidatedSlotsCleanupRightTrim) {
+  ManualGCScope manual_gc_scope;
+  CcTest::InitializeVM();
+  Heap* heap = CcTest::heap();
+  std::vector<ByteArray> byte_arrays;
+  Page* page = AllocateByteArraysOnPage(heap, &byte_arrays);
+
+  CHECK_GT(byte_arrays.size(), 1);
+  ByteArray& invalidated = byte_arrays[1];
+  int invalidated_size = invalidated.Size();
+
+  heap->RightTrimFixedArray(invalidated, invalidated.length() - 8);
+  page->RegisterObjectWithInvalidatedSlots<OLD_TO_NEW>(invalidated,
+                                                       invalidated_size);
+
+  // Free memory at end of invalidated object
+  InvalidatedSlotsCleanup cleanup = InvalidatedSlotsCleanup::OldToNew(page);
+  Address free_start = invalidated.address() + invalidated.Size();
+  cleanup.Free(free_start, page->area_end());
+
+  // After cleanup the invalidated object should be smaller
+  InvalidatedSlots* invalidated_slots = page->invalidated_slots<OLD_TO_NEW>();
+  CHECK_EQ((*invalidated_slots)[HeapObject::FromAddress(invalidated.address())],
+           invalidated.Size());
+  CHECK_EQ(invalidated_slots->size(), 1);
+}
+
 }  // namespace heap
 }  // namespace internal
 }  // namespace v8