[objects] Add ArrayBufferExtension class

This CL adds the ArrayBufferExtension class, which is used to track
JSArrayBuffers in a linked list. The ArrayBufferExtension is going to
replace the ArrayBufferTracker in the future but is currently behind
the v8_enable_array_buffer_extension feature flag.

When enabled, each JSArrayBuffer has a corresponding native-heap
allocated ArrayBufferExtension object. All extensions are currently
tracked in a single linked list. During marking the GC not only
marks the JSArrayBuffer but also its extension object. At the end of
mark-compact the GC iterates all extensions and removes unmarked ones.

Change-Id: I88298be255944d5ae1327c91b0d7f0fdbcd486d5
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1969791Reviewed-by: Peter Marshall <petermarshall@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Dominik Inführ <dinfuehr@chromium.org>
Cr-Commit-Position: refs/heads/master@{#65724}

BUILD.gn

@@ -128,7 +128,7 @@ declare_args() {
   v8_enable_concurrent_marking = true
 
   # Sets -dV8_ARRAY_BUFFER_EXTENSION
-  v8_enable_array_buffer_extension = true
+  v8_enable_array_buffer_extension = false
 
   # Enables various testing features.
   v8_enable_test_features = ""

src/builtins/builtins-typed-array-gen.cc

@@ -51,6 +51,7 @@ TNode<JSArrayBuffer> TypedArrayBuiltinsAssembler::AllocateEmptyOnHeapBuffer(
   //  - Set IsExternal and IsDetachable bits of BitFieldSlot.
   //  - Set the byte_length field to byte_length.
   //  - Set backing_store to null/Smi(0).
+  //  - Set extension to null.
   //  - Set all embedder fields to Smi(0).
   if (FIELD_SIZE(JSArrayBuffer::kOptionalPaddingOffset) != 0) {
     DCHECK_EQ(4, FIELD_SIZE(JSArrayBuffer::kOptionalPaddingOffset));
@@ -70,6 +71,11 @@ TNode<JSArrayBuffer> TypedArrayBuiltinsAssembler::AllocateEmptyOnHeapBuffer(
   StoreObjectFieldNoWriteBarrier(buffer, JSArrayBuffer::kBackingStoreOffset,
                                  IntPtrConstant(0),
                                  MachineType::PointerRepresentation());
+  if (V8_ARRAY_BUFFER_EXTENSION_BOOL) {
+    StoreObjectFieldNoWriteBarrier(buffer, JSArrayBuffer::kExtensionOffset,
+                                   IntPtrConstant(0),
+                                   MachineType::PointerRepresentation());
+  }
   for (int offset = JSArrayBuffer::kHeaderSize;
        offset < JSArrayBuffer::kSizeWithEmbedderFields; offset += kTaggedSize) {
     StoreObjectFieldNoWriteBarrier(buffer, offset, SmiConstant(0));

src/heap/heap-write-barrier-inl.h

@@ -29,6 +29,10 @@ V8_EXPORT_PRIVATE void Heap_GenerationalBarrierSlow(HeapObject object,
 V8_EXPORT_PRIVATE void Heap_MarkingBarrierSlow(HeapObject object, Address slot,
                                                HeapObject value);
 V8_EXPORT_PRIVATE void Heap_WriteBarrierForCodeSlow(Code host);
+
+V8_EXPORT_PRIVATE void Heap_MarkingBarrierForArrayBufferExtensionSlow(
+    HeapObject object, ArrayBufferExtension* extension);
+
 V8_EXPORT_PRIVATE void Heap_GenerationalBarrierForCodeSlow(Code host,
                                                            RelocInfo* rinfo,
                                                            HeapObject object);
@@ -144,6 +148,14 @@ inline void WriteBarrierForCode(Code host) {
   Heap_WriteBarrierForCodeSlow(host);
 }
 
+inline void MarkingBarrierForArrayBufferExtension(
+    HeapObject object, ArrayBufferExtension* extension) {
+  heap_internals::MemoryChunk* object_chunk =
+      heap_internals::MemoryChunk::FromHeapObject(object);
+  if (!extension || !object_chunk->IsMarking()) return;
+  Heap_MarkingBarrierForArrayBufferExtensionSlow(object, extension);
+}
+
 inline void GenerationalBarrier(HeapObject object, ObjectSlot slot,
                                 Object value) {
   if (V8_ENABLE_THIRD_PARTY_HEAP_BOOL) return;

src/heap/heap-write-barrier.h

@@ -11,6 +11,7 @@
 namespace v8 {
 namespace internal {
 
+class ArrayBufferExtension;
 class Code;
 class FixedArray;
 class Heap;
@@ -40,6 +41,9 @@ void MarkingBarrier(HeapObject object, ObjectSlot slot, HeapObject value);
 void MarkingBarrier(HeapObject object, MaybeObjectSlot slot, MaybeObject value);
 void MarkingBarrierForCode(Code host, RelocInfo* rinfo, HeapObject object);
 
+void MarkingBarrierForArrayBufferExtension(HeapObject object,
+                                           ArrayBufferExtension* extension);
+
 void MarkingBarrierForDescriptorArray(Heap* heap, HeapObject host,
                                       HeapObject descriptor_array,
                                       int number_of_own_descriptors);

src/heap/heap.cc

@@ -108,6 +108,11 @@ void Heap_WriteBarrierForCodeSlow(Code host) {
   Heap::WriteBarrierForCodeSlow(host);
 }
 
+void Heap_MarkingBarrierForArrayBufferExtensionSlow(
+    HeapObject object, ArrayBufferExtension* extension) {
+  Heap::MarkingBarrierForArrayBufferExtensionSlow(object, extension);
+}
+
 void Heap_GenerationalBarrierForCodeSlow(Code host, RelocInfo* rinfo,
                                          HeapObject object) {
   Heap::GenerationalBarrierForCodeSlow(host, rinfo, object);
@@ -3779,6 +3784,18 @@ void Heap::RemoveNearHeapLimitCallback(v8::NearHeapLimitCallback callback,
   UNREACHABLE();
 }
 
+void Heap::ReleaseAllArrayBufferExtensions() {
+  ArrayBufferExtension* current = array_buffer_extensions_;
+
+  while (current) {
+    ArrayBufferExtension* next = current->next();
+    delete current;
+    current = next;
+  }
+
+  array_buffer_extensions_ = nullptr;
+}
+
 void Heap::AutomaticallyRestoreInitialHeapLimit(double threshold_percent) {
   initial_max_old_generation_size_threshold_ =
       initial_max_old_generation_size_ * threshold_percent;
@@ -5246,6 +5263,8 @@ void Heap::TearDown() {
   // It's too late for Heap::Verify() here, as parts of the Isolate are
   // already gone by the time this is called.
 
+  ReleaseAllArrayBufferExtensions();
+
   UpdateMaximumCommitted();
 
   if (FLAG_verify_predictable || FLAG_fuzzer_gc_analysis) {
@@ -6234,6 +6253,16 @@ void Heap::WriteBarrierForCodeSlow(Code code) {
   }
 }
 
+void Heap::MarkingBarrierForArrayBufferExtensionSlow(
+    HeapObject object, ArrayBufferExtension* extension) {
+  if (V8_CONCURRENT_MARKING_BOOL || GetIsolateFromWritableObject(object)
+                                        ->heap()
+                                        ->incremental_marking()
+                                        ->marking_state()
+                                        ->IsBlack(object))
+    extension->Mark();
+}
+
 void Heap::GenerationalBarrierSlow(HeapObject object, Address slot,
                                    HeapObject value) {
   MemoryChunk* chunk = MemoryChunk::FromHeapObject(object);

src/heap/heap.h

@@ -24,6 +24,7 @@
 #include "src/objects/allocation-site.h"
 #include "src/objects/fixed-array.h"
 #include "src/objects/heap-object.h"
+#include "src/objects/js-array-buffer.h"
 #include "src/objects/objects.h"
 #include "src/objects/smi.h"
 #include "src/objects/string-table.h"
@@ -385,6 +386,10 @@ class Heap {
                                               TSlot end);
 
   V8_EXPORT_PRIVATE static void WriteBarrierForCodeSlow(Code host);
+
+  V8_EXPORT_PRIVATE static void MarkingBarrierForArrayBufferExtensionSlow(
+      HeapObject object, ArrayBufferExtension* extension);
+
   V8_EXPORT_PRIVATE static void GenerationalBarrierSlow(HeapObject object,
                                                         Address slot,
                                                         HeapObject value);
@@ -400,6 +405,10 @@ class Heap {
   V8_EXPORT_PRIVATE static void MarkingBarrierForCodeSlow(Code host,
                                                           RelocInfo* rinfo,
                                                           HeapObject value);
+
+  static void MarkingBarrierForArrayBufferExtension(
+      JSArrayBuffer object, ArrayBufferExtension* extension);
+
   V8_EXPORT_PRIVATE static void MarkingBarrierForDescriptorArraySlow(
       Heap* heap, HeapObject host, HeapObject descriptor_array,
       int number_of_own_descriptors);
@@ -575,6 +584,21 @@ class Heap {
   V8_EXPORT_PRIVATE void AutomaticallyRestoreInitialHeapLimit(
       double threshold_percent);
 
+  ArrayBufferExtension* array_buffer_extensions() {
+    return array_buffer_extensions_;
+  }
+
+  void set_array_buffer_extensions(ArrayBufferExtension* head) {
+    array_buffer_extensions_ = head;
+  }
+
+  void AppendArrayBufferExtension(ArrayBufferExtension* extension) {
+    extension->set_next(array_buffer_extensions_);
+    array_buffer_extensions_ = extension;
+  }
+
+  void ReleaseAllArrayBufferExtensions();
+
   V8_EXPORT_PRIVATE double MonotonicallyIncreasingTimeInMs();
 
   void RecordStats(HeapStats* stats, bool take_snapshot = false);
@@ -1896,6 +1920,9 @@ class Heap {
   // Map from the space id to the space.
   Space* space_[LAST_SPACE + 1];
 
+  // List for tracking ArrayBufferExtensions
+  ArrayBufferExtension* array_buffer_extensions_ = nullptr;
+
   // Determines whether code space is write-protected. This is essentially a
   // race-free copy of the {FLAG_write_protect_code_memory} flag.
   bool write_protect_code_memory_ = false;

src/heap/mark-compact.cc

@@ -885,6 +885,8 @@ void MarkCompactCollector::VerifyMarking() {
 void MarkCompactCollector::Finish() {
   TRACE_GC(heap()->tracer(), GCTracer::Scope::MC_FINISH);
 
+  SweepArrayBufferExtensions();
+
 #ifdef DEBUG
   heap()->VerifyCountersBeforeConcurrentSweeping();
 #endif
@@ -925,6 +927,28 @@ void MarkCompactCollector::Finish() {
   }
 }
 
+void MarkCompactCollector::SweepArrayBufferExtensions() {
+  if (!V8_ARRAY_BUFFER_EXTENSION_BOOL) return;
+  ArrayBufferExtension* current = heap_->array_buffer_extensions();
+  ArrayBufferExtension* last = nullptr;
+
+  while (current) {
+    ArrayBufferExtension* next = current->next();
+
+    if (!current->IsMarked()) {
+      delete current;
+    } else {
+      current->Unmark();
+      current->set_next(last);
+      last = current;
+    }
+
+    current = next;
+  }
+
+  heap_->set_array_buffer_extensions(last);
+}
+
 class MarkCompactCollector::RootMarkingVisitor final : public RootVisitor {
  public:
   explicit RootMarkingVisitor(MarkCompactCollector* collector)

src/heap/mark-compact.h

@@ -608,6 +608,9 @@ class MarkCompactCollector final : public MarkCompactCollectorBase {
   // Finishes GC, performs heap verification if enabled.
   void Finish();
 
+  // Free unmarked ArrayBufferExtensions.
+  void SweepArrayBufferExtensions();
+
   void MarkLiveObjects() override;
 
   // Marks the object black and adds it to the marking work list.

src/heap/marking-visitor-inl.h

@@ -234,6 +234,7 @@ int MarkingVisitorBase<ConcreteVisitor, MarkingState>::VisitJSApiObject(
 template <typename ConcreteVisitor, typename MarkingState>
 int MarkingVisitorBase<ConcreteVisitor, MarkingState>::VisitJSArrayBuffer(
     Map map, JSArrayBuffer object) {
+  object.MarkExtension();
   return VisitEmbedderTracingSubclass(map, object);
 }
 

src/objects/js-array-buffer-inl.h

@@ -44,17 +44,23 @@ void JSArrayBuffer::set_backing_store(void* value) {
   WriteField<Address>(kBackingStoreOffset, reinterpret_cast<Address>(value));
 }
 
-void* JSArrayBuffer::extension() const {
+ArrayBufferExtension* JSArrayBuffer::extension() const {
   if (V8_ARRAY_BUFFER_EXTENSION_BOOL) {
-    return reinterpret_cast<void*>(ReadField<Address>(kExtensionOffset));
+    return base::AsAtomicPointer::Acquire_Load(extension_location());
   } else {
     return nullptr;
   }
 }
 
-void JSArrayBuffer::set_extension(void* value) {
+ArrayBufferExtension** JSArrayBuffer::extension_location() const {
+  Address location = field_address(kExtensionOffset);
+  return reinterpret_cast<ArrayBufferExtension**>(location);
+}
+
+void JSArrayBuffer::set_extension(ArrayBufferExtension* value) {
   if (V8_ARRAY_BUFFER_EXTENSION_BOOL) {
-    WriteField<Address>(kExtensionOffset, reinterpret_cast<Address>(value));
+    base::AsAtomicPointer::Release_Store(extension_location(), value);
+    MarkingBarrierForArrayBufferExtension(*this, value);
   } else {
     CHECK_EQ(value, nullptr);
   }

src/objects/js-array-buffer.cc

@@ -63,7 +63,13 @@ void JSArrayBuffer::Attach(std::shared_ptr<BackingStore> backing_store) {
   set_byte_length(backing_store->byte_length());
   if (backing_store->is_wasm_memory()) set_is_detachable(false);
   if (!backing_store->free_on_destruct()) set_is_external(true);
-  GetIsolate()->heap()->RegisterBackingStore(*this, std::move(backing_store));
+  if (V8_ARRAY_BUFFER_EXTENSION_BOOL) {
+    Heap* heap = GetIsolate()->heap();
+    EnsureExtension(heap);
+    extension()->set_backing_store(std::move(backing_store));
+  } else {
+    GetIsolate()->heap()->RegisterBackingStore(*this, std::move(backing_store));
+  }
 }
 
 void JSArrayBuffer::Detach(bool force_for_wasm_memory) {
@@ -78,7 +84,12 @@ void JSArrayBuffer::Detach(bool force_for_wasm_memory) {
 
   Isolate* const isolate = GetIsolate();
   if (backing_store()) {
-    auto backing_store = isolate->heap()->UnregisterBackingStore(*this);
+    std::shared_ptr<BackingStore> backing_store;
+    if (V8_ARRAY_BUFFER_EXTENSION_BOOL) {
+      backing_store = RemoveExtension();
+    } else {
+      backing_store = isolate->heap()->UnregisterBackingStore(*this);
+    }
     CHECK_IMPLIES(force_for_wasm_memory, backing_store->is_wasm_memory());
   }
 
@@ -94,7 +105,40 @@ void JSArrayBuffer::Detach(bool force_for_wasm_memory) {
 }
 
 std::shared_ptr<BackingStore> JSArrayBuffer::GetBackingStore() {
-  return GetIsolate()->heap()->LookupBackingStore(*this);
+  if (V8_ARRAY_BUFFER_EXTENSION_BOOL) {
+    if (!extension()) return nullptr;
+    return extension()->backing_store();
+  } else {
+    return GetIsolate()->heap()->LookupBackingStore(*this);
+  }
+}
+
+ArrayBufferExtension* JSArrayBuffer::EnsureExtension(Heap* heap) {
+  DCHECK(V8_ARRAY_BUFFER_EXTENSION_BOOL);
+  if (extension() != nullptr) return extension();
+
+  ArrayBufferExtension* extension =
+      new ArrayBufferExtension(std::shared_ptr<BackingStore>());
+  set_extension(extension);
+  heap->AppendArrayBufferExtension(extension);
+  return extension;
+}
+
+std::shared_ptr<BackingStore> JSArrayBuffer::RemoveExtension() {
+  ArrayBufferExtension* extension = this->extension();
+  DCHECK_NOT_NULL(extension);
+  auto result = extension->RemoveBackingStore();
+  // Remove pointer to extension such that the next GC will free it
+  // automatically.
+  set_extension(nullptr);
+  return result;
+}
+
+void JSArrayBuffer::MarkExtension() {
+  ArrayBufferExtension* extension = this->extension();
+  if (extension) {
+    extension->Mark();
+  }
 }
 
 Handle<JSArrayBuffer> JSTypedArray::GetBuffer() {

src/objects/js-array-buffer.h

@@ -15,6 +15,8 @@
 namespace v8 {
 namespace internal {
 
+class ArrayBufferExtension;
+
 class JSArrayBuffer : public JSObject {
  public:
 // The maximum length for JSArrayBuffer's supported by V8.
@@ -34,7 +36,7 @@ class JSArrayBuffer : public JSObject {
   DECL_PRIMITIVE_ACCESSORS(backing_store, void*)
 
   // [extension]: extension object used for GC
-  DECL_PRIMITIVE_ACCESSORS(extension, void*)
+  DECL_PRIMITIVE_ACCESSORS(extension, ArrayBufferExtension*)
 
   // For non-wasm, allocation_length and allocation_base are byte_length and
   // backing_store, respectively.
@@ -103,6 +105,16 @@ class JSArrayBuffer : public JSObject {
   // or a zero-length array buffer).
   std::shared_ptr<BackingStore> GetBackingStore();
 
+  // Allocates an ArrayBufferExtension for this array buffer, unless it is
+  // already associated with an extension.
+  ArrayBufferExtension* EnsureExtension(Heap* heap);
+
+  // Frees the associated ArrayBufferExtension and returns its backing store.
+  std::shared_ptr<BackingStore> RemoveExtension();
+
+  // Marks ArrayBufferExtension
+  void MarkExtension();
+
   // Dispatched behavior.
   DECL_PRINTER(JSArrayBuffer)
   DECL_VERIFIER(JSArrayBuffer)
@@ -131,6 +143,49 @@ class JSArrayBuffer : public JSObject {
   class BodyDescriptor;
 
   OBJECT_CONSTRUCTORS(JSArrayBuffer, JSObject);
+
+ private:
+  inline ArrayBufferExtension** extension_location() const;
+};
+
+// Each JSArrayBuffer (with a backing store) has a corresponding native-heap
+// allocated ArrayBufferExtension for GC purposes and storing the backing store.
+// When marking a JSArrayBuffer, the GC also marks the native
+// extension-object. The GC periodically iterates all extensions concurrently
+// and frees unmarked ones.
+// https://docs.google.com/document/d/1-ZrLdlFX1nXT3z-FAgLbKal1gI8Auiaya_My-a0UJ28/edit
+class ArrayBufferExtension : public Malloced {
+  std::atomic<bool> marked_;
+  std::shared_ptr<BackingStore> backing_store_;
+  ArrayBufferExtension* next_;
+
+ public:
+  ArrayBufferExtension()
+      : marked_(false),
+        backing_store_(std::shared_ptr<BackingStore>()),
+        next_(nullptr) {}
+  explicit ArrayBufferExtension(std::shared_ptr<BackingStore> backing_store)
+      : marked_(false), backing_store_(backing_store), next_(nullptr) {}
+
+  void Mark() { marked_.store(true, std::memory_order_relaxed); }
+  void Unmark() { marked_.store(false, std::memory_order_relaxed); }
+  bool IsMarked() { return marked_.load(std::memory_order_relaxed); }
+
+  std::shared_ptr<BackingStore> backing_store() { return backing_store_; }
+  BackingStore* backing_store_raw() { return backing_store_.get(); }
+
+  std::shared_ptr<BackingStore> RemoveBackingStore() {
+    return std::move(backing_store_);
+  }
+
+  void set_backing_store(std::shared_ptr<BackingStore> backing_store) {
+    backing_store_ = std::move(backing_store);
+  }
+
+  void reset_backing_store() { backing_store_.reset(); }
+
+  ArrayBufferExtension* next() { return next_; }
+  void set_next(ArrayBufferExtension* extension) { next_ = extension; }
 };
 
 class JSArrayBufferView : public JSObject {

src/snapshot/deserializer.cc

@@ -301,6 +301,7 @@ HeapObject Deserializer::PostProcessNewObject(HeapObject obj,
     }
   } else if (obj.IsJSArrayBuffer()) {
     JSArrayBuffer buffer = JSArrayBuffer::cast(obj);
+    buffer.set_extension(nullptr);
     // Only fixup for the off-heap case. This may trigger GC.
     if (buffer.backing_store() != nullptr) {
       new_off_heap_array_buffers_.push_back(handle(buffer, isolate_));

test/cctest/heap/test-array-buffer-tracker.cc

@@ -30,6 +30,7 @@ namespace heap {
 // moving the objects through various spaces during GC phases.
 
 TEST(ArrayBuffer_OnlyMC) {
+  if (V8_ARRAY_BUFFER_EXTENSION_BOOL) return;
   ManualGCScope manual_gc_scope;
   CcTest::InitializeVM();
   LocalContext env;
@@ -58,6 +59,7 @@ TEST(ArrayBuffer_OnlyMC) {
 }
 
 TEST(ArrayBuffer_OnlyScavenge) {
+  if (V8_ARRAY_BUFFER_EXTENSION_BOOL) return;
   ManualGCScope manual_gc_scope;
   CcTest::InitializeVM();
   LocalContext env;
@@ -88,6 +90,7 @@ TEST(ArrayBuffer_OnlyScavenge) {
 }
 
 TEST(ArrayBuffer_ScavengeAndMC) {
+  if (V8_ARRAY_BUFFER_EXTENSION_BOOL) return;
   ManualGCScope manual_gc_scope;
   CcTest::InitializeVM();
   LocalContext env;
@@ -120,7 +123,7 @@ TEST(ArrayBuffer_ScavengeAndMC) {
 }
 
 TEST(ArrayBuffer_Compaction) {
-  if (FLAG_never_compact) return;
+  if (FLAG_never_compact || V8_ARRAY_BUFFER_EXTENSION_BOOL) return;
   ManualGCScope manual_gc_scope;
   FLAG_manual_evacuation_candidates_selection = true;
   CcTest::InitializeVM();
@@ -149,6 +152,7 @@ TEST(ArrayBuffer_Compaction) {
 }
 
 TEST(ArrayBuffer_UnregisterDuringSweep) {
+  if (V8_ARRAY_BUFFER_EXTENSION_BOOL) return;
 // Regular pages in old space (without compaction) are processed concurrently
 // in the sweeper. If we happen to unregister a buffer (either explicitly, or
 // implicitly through e.g. |Detach|) we need to sync with the sweeper
@@ -197,7 +201,7 @@ TEST(ArrayBuffer_UnregisterDuringSweep) {
 }
 
 TEST(ArrayBuffer_NonLivePromotion) {
-  if (!FLAG_incremental_marking) return;
+  if (!FLAG_incremental_marking || V8_ARRAY_BUFFER_EXTENSION_BOOL) return;
   ManualGCScope manual_gc_scope;
   // The test verifies that the marking state is preserved when promoting
   // a buffer to old space.
@@ -234,7 +238,7 @@ TEST(ArrayBuffer_NonLivePromotion) {
 }
 
 TEST(ArrayBuffer_LivePromotion) {
-  if (!FLAG_incremental_marking) return;
+  if (!FLAG_incremental_marking || V8_ARRAY_BUFFER_EXTENSION_BOOL) return;
   ManualGCScope manual_gc_scope;
   // The test verifies that the marking state is preserved when promoting
   // a buffer to old space.
@@ -270,7 +274,7 @@ TEST(ArrayBuffer_LivePromotion) {
 }
 
 TEST(ArrayBuffer_SemiSpaceCopyThenPagePromotion) {
-  if (!i::FLAG_incremental_marking) return;
+  if (!i::FLAG_incremental_marking || V8_ARRAY_BUFFER_EXTENSION_BOOL) return;
   ManualGCScope manual_gc_scope;
   // The test verifies that the marking state is preserved across semispace
   // copy.
@@ -337,6 +341,7 @@ UNINITIALIZED_TEST(ArrayBuffer_SemiSpaceCopyMultipleTasks) {
 }
 
 TEST(ArrayBuffer_ExternalBackingStoreSizeIncreases) {
+  if (V8_ARRAY_BUFFER_EXTENSION_BOOL) return;
   CcTest::InitializeVM();
   LocalContext env;
   v8::Isolate* isolate = env->GetIsolate();
@@ -378,7 +383,7 @@ TEST(ArrayBuffer_ExternalBackingStoreSizeDecreases) {
 }
 
 TEST(ArrayBuffer_ExternalBackingStoreSizeIncreasesMarkCompact) {
-  if (FLAG_never_compact) return;
+  if (FLAG_never_compact || V8_ARRAY_BUFFER_EXTENSION_BOOL) return;
   ManualGCScope manual_gc_scope;
   FLAG_manual_evacuation_candidates_selection = true;
   CcTest::InitializeVM();

test/cctest/heap/test-page-promotion.cc

@@ -167,7 +167,8 @@ UNINITIALIZED_TEST(PagePromotion_NewToNewJSArrayBuffer) {
     CHECK(heap->new_space()->ToSpaceContainsSlow(buffer->address()));
     CHECK(to_be_promoted_page->Contains(first_object->address()));
     CHECK(to_be_promoted_page->Contains(buffer->address()));
-    CHECK(ArrayBufferTracker::IsTracked(*buffer));
+    if (!V8_ARRAY_BUFFER_EXTENSION_BOOL)
+      CHECK(ArrayBufferTracker::IsTracked(*buffer));
   }
   isolate->Dispose();
 }
@@ -212,7 +213,8 @@ UNINITIALIZED_TEST(PagePromotion_NewToOldJSArrayBuffer) {
     CHECK(heap->old_space()->ContainsSlow(buffer->address()));
     CHECK(to_be_promoted_page->Contains(first_object->address()));
     CHECK(to_be_promoted_page->Contains(buffer->address()));
-    CHECK(ArrayBufferTracker::IsTracked(*buffer));
+    if (!V8_ARRAY_BUFFER_EXTENSION_BOOL)
+      CHECK(ArrayBufferTracker::IsTracked(*buffer));
   }
   isolate->Dispose();
 }