Remove the weak list of array buffers
authorjochen <jochen@chromium.org>
Wed, 29 Apr 2015 13:04:43 +0000 (06:04 -0700)
committerCommit bot <commit-bot@chromium.org>
Wed, 29 Apr 2015 13:04:55 +0000 (13:04 +0000)
Instead, collect live array buffers during marking and free pointers we
no longer found.

BUG=v8:3996
R=hpayer@chromium.org
LOG=n

Review URL: https://codereview.chromium.org/1114563002

Cr-Commit-Position: refs/heads/master@{#28132}

15 files changed:
src/api.cc
src/heap-snapshot-generator.cc
src/heap/heap.cc
src/heap/heap.h
src/heap/mark-compact.cc
src/heap/objects-visiting-inl.h
src/heap/objects-visiting.cc
src/heap/objects-visiting.h
src/objects-inl.h
src/objects.h
src/runtime/runtime-typedarray.cc
src/runtime/runtime.h
src/snapshot/serialize.cc
test/cctest/cctest.gyp
test/cctest/test-weaktypedarrays.cc [deleted file]

index de0b007..c42cab6 100644 (file)
@@ -6254,9 +6254,12 @@ bool v8::ArrayBuffer::IsNeuterable() const {
 
 v8::ArrayBuffer::Contents v8::ArrayBuffer::Externalize() {
   i::Handle<i::JSArrayBuffer> self = Utils::OpenHandle(this);
+  i::Isolate* isolate = self->GetIsolate();
   Utils::ApiCheck(!self->is_external(), "v8::ArrayBuffer::Externalize",
                   "ArrayBuffer already externalized");
   self->set_is_external(true);
+  isolate->heap()->UnregisterArrayBuffer(self->backing_store());
+
   return GetContents();
 }
 
index 654cda4..34db11b 100644 (file)
@@ -1566,8 +1566,6 @@ class JSArrayBufferDataEntryAllocator : public HeapEntriesAllocator {
 
 void V8HeapExplorer::ExtractJSArrayBufferReferences(
     int entry, JSArrayBuffer* buffer) {
-  SetWeakReference(buffer, entry, "weak_next", buffer->weak_next(),
-                   JSArrayBuffer::kWeakNextOffset);
   // Setup a reference to a native memory backing_store object.
   if (!buffer->backing_store())
     return;
index 8d34738..fac9535 100644 (file)
@@ -154,8 +154,6 @@ Heap::Heap()
 
   memset(roots_, 0, sizeof(roots_[0]) * kRootListLength);
   set_native_contexts_list(NULL);
-  set_array_buffers_list(Smi::FromInt(0));
-  set_last_array_buffer_in_list(Smi::FromInt(0));
   set_allocation_sites_list(Smi::FromInt(0));
   set_encountered_weak_collections(Smi::FromInt(0));
   set_encountered_weak_cells(Smi::FromInt(0));
@@ -1705,64 +1703,67 @@ void Heap::UpdateReferencesInExternalStringTable(
 
 
 void Heap::ProcessAllWeakReferences(WeakObjectRetainer* retainer) {
-  ProcessArrayBuffers(retainer, false);
   ProcessNativeContexts(retainer);
   ProcessAllocationSites(retainer);
 }
 
 
 void Heap::ProcessYoungWeakReferences(WeakObjectRetainer* retainer) {
-  ProcessArrayBuffers(retainer, true);
   ProcessNativeContexts(retainer);
 }
 
 
 void Heap::ProcessNativeContexts(WeakObjectRetainer* retainer) {
-  Object* head = VisitWeakList<Context>(this, native_contexts_list(), retainer,
-                                        false, NULL);
+  Object* head = VisitWeakList<Context>(this, native_contexts_list(), retainer);
   // Update the head of the list of contexts.
   set_native_contexts_list(head);
 }
 
 
-void Heap::ProcessArrayBuffers(WeakObjectRetainer* retainer,
-                               bool stop_after_young) {
-  Object* last_array_buffer = undefined_value();
-  Object* array_buffer_obj =
-      VisitWeakList<JSArrayBuffer>(this, array_buffers_list(), retainer,
-                                   stop_after_young, &last_array_buffer);
-  set_array_buffers_list(array_buffer_obj);
-  set_last_array_buffer_in_list(last_array_buffer);
-
-  // Verify invariant that young array buffers come before old array buffers
-  // in array buffers list if there was no promotion failure.
-  Object* undefined = undefined_value();
-  Object* next = array_buffers_list();
-  bool old_objects_recorded = false;
-  while (next != undefined) {
-    if (!old_objects_recorded) {
-      old_objects_recorded = !InNewSpace(next);
-    }
-    CHECK((InNewSpace(next) && !old_objects_recorded) || !InNewSpace(next));
-    next = JSArrayBuffer::cast(next)->weak_next();
+void Heap::RegisterNewArrayBuffer(void* data, size_t length) {
+  live_array_buffers_[data] = length;
+  reinterpret_cast<v8::Isolate*>(isolate_)
+      ->AdjustAmountOfExternalAllocatedMemory(length);
+}
+
+
+void Heap::UnregisterArrayBuffer(void* data) {
+  DCHECK(live_array_buffers_.count(data) > 0);
+  live_array_buffers_.erase(data);
+  not_yet_discovered_array_buffers_.erase(data);
+}
+
+
+void Heap::RegisterLiveArrayBuffer(void* data) {
+  not_yet_discovered_array_buffers_.erase(data);
+}
+
+
+void Heap::FreeDeadArrayBuffers() {
+  for (auto buffer = not_yet_discovered_array_buffers_.begin();
+       buffer != not_yet_discovered_array_buffers_.end(); ++buffer) {
+    isolate_->array_buffer_allocator()->Free(buffer->first, buffer->second);
+    // Don't use the API method here since this could trigger another GC.
+    amount_of_external_allocated_memory_ -= buffer->second;
+    live_array_buffers_.erase(buffer->first);
   }
+  not_yet_discovered_array_buffers_ = live_array_buffers_;
 }
 
 
 void Heap::TearDownArrayBuffers() {
-  Object* undefined = undefined_value();
-  for (Object* o = array_buffers_list(); o != undefined;) {
-    JSArrayBuffer* buffer = JSArrayBuffer::cast(o);
-    Runtime::FreeArrayBuffer(isolate(), buffer);
-    o = buffer->weak_next();
+  for (auto buffer = live_array_buffers_.begin();
+       buffer != live_array_buffers_.end(); ++buffer) {
+    isolate_->array_buffer_allocator()->Free(buffer->first, buffer->second);
   }
-  set_array_buffers_list(undefined);
+  live_array_buffers_.clear();
+  not_yet_discovered_array_buffers_.clear();
 }
 
 
 void Heap::ProcessAllocationSites(WeakObjectRetainer* retainer) {
-  Object* allocation_site_obj = VisitWeakList<AllocationSite>(
-      this, allocation_sites_list(), retainer, false, NULL);
+  Object* allocation_site_obj =
+      VisitWeakList<AllocationSite>(this, allocation_sites_list(), retainer);
   set_allocation_sites_list(allocation_site_obj);
 }
 
@@ -5407,8 +5408,6 @@ bool Heap::CreateHeapObjects() {
   CHECK_EQ(0u, gc_count_);
 
   set_native_contexts_list(undefined_value());
-  set_array_buffers_list(undefined_value());
-  set_last_array_buffer_in_list(undefined_value());
   set_allocation_sites_list(undefined_value());
   return true;
 }
index d019293..75e47ea 100644 (file)
@@ -6,6 +6,7 @@
 #define V8_HEAP_HEAP_H_
 
 #include <cmath>
+#include <map>
 
 #include "src/allocation.h"
 #include "src/assert-scope.h"
@@ -874,16 +875,6 @@ class Heap {
   }
   Object* native_contexts_list() const { return native_contexts_list_; }
 
-  void set_array_buffers_list(Object* object) { array_buffers_list_ = object; }
-  Object* array_buffers_list() const { return array_buffers_list_; }
-
-  void set_last_array_buffer_in_list(Object* object) {
-    last_array_buffer_in_list_ = object;
-  }
-  Object* last_array_buffer_in_list() const {
-    return last_array_buffer_in_list_;
-  }
-
   void set_allocation_sites_list(Object* object) {
     allocation_sites_list_ = object;
   }
@@ -1490,6 +1481,11 @@ class Heap {
 
   bool deserialization_complete() const { return deserialization_complete_; }
 
+  void RegisterNewArrayBuffer(void* data, size_t length);
+  void UnregisterArrayBuffer(void* data);
+  void RegisterLiveArrayBuffer(void* data);
+  void FreeDeadArrayBuffers();
+
  protected:
   // Methods made available to tests.
 
@@ -1660,8 +1656,6 @@ class Heap {
   // Weak list heads, threaded through the objects.
   // List heads are initialized lazily and contain the undefined_value at start.
   Object* native_contexts_list_;
-  Object* array_buffers_list_;
-  Object* last_array_buffer_in_list_;
   Object* allocation_sites_list_;
 
   // List of encountered weak collections (JSWeakMap and JSWeakSet) during
@@ -1995,7 +1989,6 @@ class Heap {
   void MarkCompactEpilogue();
 
   void ProcessNativeContexts(WeakObjectRetainer* retainer);
-  void ProcessArrayBuffers(WeakObjectRetainer* retainer, bool stop_after_young);
   void ProcessAllocationSites(WeakObjectRetainer* retainer);
 
   // Deopts all code that contains allocation instruction which are tenured or
@@ -2156,6 +2149,9 @@ class Heap {
 
   bool concurrent_sweeping_enabled_;
 
+  std::map<void*, size_t> live_array_buffers_;
+  std::map<void*, size_t> not_yet_discovered_array_buffers_;
+
   friend class AlwaysAllocateScope;
   friend class Deserializer;
   friend class Factory;
index 17190c6..ac0499a 100644 (file)
@@ -4386,6 +4386,8 @@ void MarkCompactCollector::SweepSpaces() {
 #ifdef DEBUG
   state_ = SWEEP_SPACES;
 #endif
+  heap()->FreeDeadArrayBuffers();
+
   MoveEvacuationCandidatesToEndOfPagesList();
 
   // Noncompacting collections simply sweep the spaces to clear the mark
index 39803b1..6afee26 100644 (file)
@@ -80,12 +80,9 @@ int StaticNewSpaceVisitor<StaticVisitor>::VisitJSArrayBuffer(
     Map* map, HeapObject* object) {
   Heap* heap = map->GetHeap();
 
-  VisitPointers(heap, HeapObject::RawField(
-                          object, JSArrayBuffer::BodyDescriptor::kStartOffset),
-                HeapObject::RawField(object, JSArrayBuffer::kWeakNextOffset));
   VisitPointers(
-      heap, HeapObject::RawField(object,
-                                 JSArrayBuffer::kWeakNextOffset + kPointerSize),
+      heap,
+      HeapObject::RawField(object, JSArrayBuffer::BodyDescriptor::kStartOffset),
       HeapObject::RawField(object, JSArrayBuffer::kSizeWithInternalFields));
   return JSArrayBuffer::kSizeWithInternalFields;
 }
@@ -533,11 +530,10 @@ void StaticMarkingVisitor<StaticVisitor>::VisitJSArrayBuffer(
   StaticVisitor::VisitPointers(
       heap,
       HeapObject::RawField(object, JSArrayBuffer::BodyDescriptor::kStartOffset),
-      HeapObject::RawField(object, JSArrayBuffer::kWeakNextOffset));
-  StaticVisitor::VisitPointers(
-      heap, HeapObject::RawField(object,
-                                 JSArrayBuffer::kWeakNextOffset + kPointerSize),
       HeapObject::RawField(object, JSArrayBuffer::kSizeWithInternalFields));
+  if (!JSArrayBuffer::cast(object)->is_external()) {
+    heap->RegisterLiveArrayBuffer(JSArrayBuffer::cast(object)->backing_store());
+  }
 }
 
 
index 8c2f198..de2cfdd 100644 (file)
@@ -191,8 +191,7 @@ struct WeakListVisitor;
 
 
 template <class T>
-Object* VisitWeakList(Heap* heap, Object* list, WeakObjectRetainer* retainer,
-                      bool stop_after_young, Object** list_tail) {
+Object* VisitWeakList(Heap* heap, Object* list, WeakObjectRetainer* retainer) {
   Object* undefined = heap->undefined_value();
   Object* head = undefined;
   T* tail = NULL;
@@ -235,10 +234,7 @@ Object* VisitWeakList(Heap* heap, Object* list, WeakObjectRetainer* retainer,
   }
 
   // Terminate the list if there is one or more elements.
-  if (tail != NULL) {
-    WeakListVisitor<T>::SetWeakNext(tail, undefined);
-    if (list_tail) *list_tail = tail;
-  }
+  if (tail != NULL) WeakListVisitor<T>::SetWeakNext(tail, undefined);
   return head;
 }
 
@@ -320,8 +316,7 @@ struct WeakListVisitor<Context> {
   static void DoWeakList(Heap* heap, Context* context,
                          WeakObjectRetainer* retainer, int index) {
     // Visit the weak list, removing dead intermediate elements.
-    Object* list_head =
-        VisitWeakList<T>(heap, context->get(index), retainer, false, NULL);
+    Object* list_head = VisitWeakList<T>(heap, context->get(index), retainer);
 
     // Update the list head.
     context->set(index, list_head, UPDATE_WRITE_BARRIER);
@@ -345,26 +340,6 @@ struct WeakListVisitor<Context> {
 
 
 template <>
-struct WeakListVisitor<JSArrayBuffer> {
-  static void SetWeakNext(JSArrayBuffer* obj, Object* next) {
-    obj->set_weak_next(next);
-  }
-
-  static Object* WeakNext(JSArrayBuffer* obj) { return obj->weak_next(); }
-
-  static int WeakNextOffset() { return JSArrayBuffer::kWeakNextOffset; }
-
-  static void VisitLiveObject(Heap* heap, JSArrayBuffer* array_buffer,
-                              WeakObjectRetainer* retainer) {
-  }
-
-  static void VisitPhantomObject(Heap* heap, JSArrayBuffer* phantom) {
-    Runtime::FreeArrayBuffer(heap->isolate(), phantom);
-  }
-};
-
-
-template <>
 struct WeakListVisitor<AllocationSite> {
   static void SetWeakNext(AllocationSite* obj, Object* next) {
     obj->set_weak_next(next);
@@ -381,19 +356,9 @@ struct WeakListVisitor<AllocationSite> {
 
 
 template Object* VisitWeakList<Context>(Heap* heap, Object* list,
-                                        WeakObjectRetainer* retainer,
-                                        bool stop_after_young,
-                                        Object** list_tail);
-
-
-template Object* VisitWeakList<JSArrayBuffer>(Heap* heap, Object* list,
-                                              WeakObjectRetainer* retainer,
-                                              bool stop_after_young,
-                                              Object** list_tail);
+                                        WeakObjectRetainer* retainer);
 
 template Object* VisitWeakList<AllocationSite>(Heap* heap, Object* list,
-                                               WeakObjectRetainer* retainer,
-                                               bool stop_after_young,
-                                               Object** list_tail);
+                                               WeakObjectRetainer* retainer);
 }
 }  // namespace v8::internal
index 12da9e9..87785e5 100644 (file)
@@ -490,10 +490,7 @@ class WeakObjectRetainer;
 // pointers. The template parameter T is a WeakListVisitor that defines how to
 // access the next-element pointers.
 template <class T>
-Object* VisitWeakList(Heap* heap, Object* list, WeakObjectRetainer* retainer,
-                      bool stop_after_young, Object** list_tail);
-Object* VisitNewArrayBufferViewsWeakList(Heap* heap, Object* list,
-                                         WeakObjectRetainer* retainer);
+Object* VisitWeakList(Heap* heap, Object* list, WeakObjectRetainer* retainer);
 }
 }  // namespace v8::internal
 
index 6f97245..39f5bf0 100644 (file)
@@ -6470,9 +6470,6 @@ void JSArrayBuffer::set_was_neutered(bool value) {
 }
 
 
-ACCESSORS(JSArrayBuffer, weak_next, Object, kWeakNextOffset)
-
-
 Object* JSArrayBufferView::byte_offset() const {
   if (WasNeutered()) return Smi::FromInt(0);
   return Object::cast(READ_FIELD(this, kByteOffsetOffset));
index 7244d17..fef2d77 100644 (file)
@@ -10258,9 +10258,6 @@ class JSArrayBuffer: public JSObject {
   inline bool was_neutered();
   inline void set_was_neutered(bool value);
 
-  // [weak_next]: linked list of array buffers.
-  DECL_ACCESSORS(weak_next, Object)
-
   DECLARE_CAST(JSArrayBuffer)
 
   void Neuter();
@@ -10277,8 +10274,7 @@ class JSArrayBuffer: public JSObject {
 #else
   static const int kBitFieldOffset = kBitFieldSlot + kIntSize;
 #endif
-  static const int kWeakNextOffset = kBitFieldSlot + kPointerSize;
-  static const int kSize = kWeakNextOffset + kPointerSize;
+  static const int kSize = kBitFieldSlot + kPointerSize;
 
   static const int kSizeWithInternalFields =
       kSize + v8::ArrayBuffer::kInternalFieldCount * kPointerSize;
index 036ee41..b95d20f 100644 (file)
 namespace v8 {
 namespace internal {
 
-void Runtime::FreeArrayBuffer(Isolate* isolate,
-                              JSArrayBuffer* phantom_array_buffer) {
-  if (phantom_array_buffer->is_external()) return;
-
-  size_t allocated_length =
-      NumberToSize(isolate, phantom_array_buffer->byte_length());
-
-  reinterpret_cast<v8::Isolate*>(isolate)
-      ->AdjustAmountOfExternalAllocatedMemory(
-          -static_cast<int64_t>(allocated_length));
-  CHECK(isolate->array_buffer_allocator() != NULL);
-  isolate->array_buffer_allocator()->Free(phantom_array_buffer->backing_store(),
-                                          allocated_length);
-}
-
-
 void Runtime::SetupArrayBuffer(Isolate* isolate,
                                Handle<JSArrayBuffer> array_buffer,
                                bool is_external, void* data,
@@ -47,17 +31,8 @@ void Runtime::SetupArrayBuffer(Isolate* isolate,
   CHECK(byte_length->IsSmi() || byte_length->IsHeapNumber());
   array_buffer->set_byte_length(*byte_length);
 
-  if (isolate->heap()->InNewSpace(*array_buffer) ||
-      isolate->heap()->array_buffers_list()->IsUndefined()) {
-    array_buffer->set_weak_next(isolate->heap()->array_buffers_list());
-    isolate->heap()->set_array_buffers_list(*array_buffer);
-    if (isolate->heap()->last_array_buffer_in_list()->IsUndefined()) {
-      isolate->heap()->set_last_array_buffer_in_list(*array_buffer);
-    }
-  } else {
-    JSArrayBuffer::cast(isolate->heap()->last_array_buffer_in_list())
-        ->set_weak_next(*array_buffer);
-    isolate->heap()->set_last_array_buffer_in_list(*array_buffer);
+  if (data && !is_external) {
+    isolate->heap()->RegisterNewArrayBuffer(data, allocated_length);
   }
 }
 
@@ -83,10 +58,6 @@ bool Runtime::SetupArrayBufferAllocatingData(Isolate* isolate,
   }
 
   SetupArrayBuffer(isolate, array_buffer, false, data, allocated_length);
-
-  reinterpret_cast<v8::Isolate*>(isolate)
-      ->AdjustAmountOfExternalAllocatedMemory(allocated_length);
-
   return true;
 }
 
@@ -173,6 +144,7 @@ RUNTIME_FUNCTION(Runtime_ArrayBufferNeuter) {
   size_t byte_length = NumberToSize(isolate, array_buffer->byte_length());
   array_buffer->set_is_external(true);
   Runtime::NeuterArrayBuffer(array_buffer);
+  isolate->heap()->UnregisterArrayBuffer(backing_store);
   isolate->array_buffer_allocator()->Free(backing_store, byte_length);
   return isolate->heap()->undefined_value();
 }
index eeaa873..af3e135 100644 (file)
@@ -817,9 +817,6 @@ class Runtime : public AllStatic {
 
   static void NeuterArrayBuffer(Handle<JSArrayBuffer> array_buffer);
 
-  static void FreeArrayBuffer(Isolate* isolate,
-                              JSArrayBuffer* phantom_array_buffer);
-
   static int FindIndexedNonNativeFrame(JavaScriptFrameIterator* it, int index);
 
   enum TypedArrayId {
index 26f8da3..dbe92a6 100644 (file)
@@ -563,10 +563,6 @@ void Deserializer::Deserialize(Isolate* isolate) {
 
   isolate_->heap()->set_native_contexts_list(
       isolate_->heap()->undefined_value());
-  isolate_->heap()->set_array_buffers_list(
-      isolate_->heap()->undefined_value());
-  isolate_->heap()->set_last_array_buffer_in_list(
-      isolate_->heap()->undefined_value());
 
   // The allocation site list is build during root iteration, but if no sites
   // were encountered then it needs to be initialized to undefined.
index 1603275..0b73e15 100644 (file)
         'test-version.cc',
         'test-weakmaps.cc',
         'test-weaksets.cc',
-        'test-weaktypedarrays.cc',
         'trace-extension.cc',
         '../../src/startup-data-util.h',
         '../../src/startup-data-util.cc'
diff --git a/test/cctest/test-weaktypedarrays.cc b/test/cctest/test-weaktypedarrays.cc
deleted file mode 100644 (file)
index c0d2950..0000000
+++ /dev/null
@@ -1,124 +0,0 @@
-// Copyright 2013 the V8 project authors. All rights reserved.
-// Redistribution and use in source and binary forms, with or without
-// modification, are permitted provided that the following conditions are
-// met:
-//
-//     * Redistributions of source code must retain the above copyright
-//       notice, this list of conditions and the following disclaimer.
-//     * Redistributions in binary form must reproduce the above
-//       copyright notice, this list of conditions and the following
-//       disclaimer in the documentation and/or other materials provided
-//       with the distribution.
-//     * Neither the name of Google Inc. nor the names of its
-//       contributors may be used to endorse or promote products derived
-//       from this software without specific prior written permission.
-//
-// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-
-#include <stdlib.h>
-
-#include "src/v8.h"
-#include "test/cctest/cctest.h"
-
-#include "src/api.h"
-#include "src/heap/heap.h"
-#include "src/objects.h"
-
-using namespace v8::internal;
-
-static Isolate* GetIsolateFrom(LocalContext* context) {
-  return reinterpret_cast<Isolate*>((*context)->GetIsolate());
-}
-
-
-static int CountArrayBuffersInWeakList(Heap* heap) {
-  int count = 0;
-  for (Object* o = heap->array_buffers_list();
-       !o->IsUndefined();
-       o = JSArrayBuffer::cast(o)->weak_next()) {
-    count++;
-  }
-  return count;
-}
-
-
-static bool HasArrayBufferInWeakList(Heap* heap, JSArrayBuffer* ab) {
-  for (Object* o = heap->array_buffers_list();
-       !o->IsUndefined();
-       o = JSArrayBuffer::cast(o)->weak_next()) {
-    if (ab == o) return true;
-  }
-  return false;
-}
-
-
-TEST(WeakArrayBuffersFromScript) {
-  v8::V8::Initialize();
-  LocalContext context;
-  Isolate* isolate = GetIsolateFrom(&context);
-  int start = CountArrayBuffersInWeakList(isolate->heap());
-
-  for (int i = 1; i <= 3; i++) {
-    // Create 3 array buffers, make i-th of them garbage,
-    // validate correct state of array buffer weak list.
-    CHECK_EQ(start, CountArrayBuffersInWeakList(isolate->heap()));
-    {
-      v8::HandleScope scope(context->GetIsolate());
-
-      {
-        v8::HandleScope s1(context->GetIsolate());
-        CompileRun("var ab1 = new ArrayBuffer(256);"
-                   "var ab2 = new ArrayBuffer(256);"
-                   "var ab3 = new ArrayBuffer(256);");
-        v8::Handle<v8::ArrayBuffer> ab1 =
-            v8::Handle<v8::ArrayBuffer>::Cast(CompileRun("ab1"));
-        v8::Handle<v8::ArrayBuffer> ab2 =
-            v8::Handle<v8::ArrayBuffer>::Cast(CompileRun("ab2"));
-        v8::Handle<v8::ArrayBuffer> ab3 =
-            v8::Handle<v8::ArrayBuffer>::Cast(CompileRun("ab3"));
-
-        CHECK_EQ(3, CountArrayBuffersInWeakList(isolate->heap()) - start);
-        CHECK(HasArrayBufferInWeakList(isolate->heap(),
-              *v8::Utils::OpenHandle(*ab1)));
-        CHECK(HasArrayBufferInWeakList(isolate->heap(),
-              *v8::Utils::OpenHandle(*ab2)));
-        CHECK(HasArrayBufferInWeakList(isolate->heap(),
-              *v8::Utils::OpenHandle(*ab3)));
-      }
-
-      i::ScopedVector<char> source(1024);
-      i::SNPrintF(source, "ab%d = null;", i);
-      CompileRun(source.start());
-      isolate->heap()->CollectAllGarbage();
-
-      CHECK_EQ(2, CountArrayBuffersInWeakList(isolate->heap()) - start);
-
-      {
-        v8::HandleScope s2(context->GetIsolate());
-        for (int j = 1; j <= 3; j++) {
-          if (j == i) continue;
-          i::SNPrintF(source, "ab%d", j);
-          v8::Handle<v8::ArrayBuffer> ab =
-              v8::Handle<v8::ArrayBuffer>::Cast(CompileRun(source.start()));
-          CHECK(HasArrayBufferInWeakList(isolate->heap(),
-                *v8::Utils::OpenHandle(*ab)));
-          }
-      }
-
-      CompileRun("ab1 = null; ab2 = null; ab3 = null;");
-    }
-
-    isolate->heap()->CollectAllGarbage();
-    CHECK_EQ(start, CountArrayBuffersInWeakList(isolate->heap()));
-  }
-}