Keep track of array buffers in new space separately

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

Review URL: https://codereview.chromium.org/1133773002

Cr-Commit-Position: refs/heads/master@{#28978}

src/api.cc

@@ -6531,7 +6531,8 @@ v8::ArrayBuffer::Contents v8::ArrayBuffer::Externalize() {
   Utils::ApiCheck(!self->is_external(), "v8::ArrayBuffer::Externalize",
                   "ArrayBuffer already externalized");
   self->set_is_external(true);
-  isolate->heap()->UnregisterArrayBuffer(self->backing_store());
+  isolate->heap()->UnregisterArrayBuffer(isolate->heap()->InNewSpace(*self),
+                                         self->backing_store());
 
   return GetContents();
 }
@@ -6738,7 +6739,8 @@ v8::SharedArrayBuffer::Contents v8::SharedArrayBuffer::Externalize() {
   Utils::ApiCheck(!self->is_external(), "v8::SharedArrayBuffer::Externalize",
                   "SharedArrayBuffer already externalized");
   self->set_is_external(true);
-  isolate->heap()->UnregisterArrayBuffer(self->backing_store());
+  isolate->heap()->UnregisterArrayBuffer(isolate->heap()->InNewSpace(*self),
+                                         self->backing_store());
   return GetContents();
 }
 

src/heap/heap.cc

@@ -1623,6 +1623,8 @@ void Heap::Scavenge() {
 
   SelectScavengingVisitorsTable();
 
+  PrepareArrayBufferDiscoveryInNewSpace();
+
   // Flip the semispaces.  After flipping, to space is empty, from space has
   // live objects.
   new_space_.Flip();
@@ -1704,6 +1706,8 @@ void Heap::Scavenge() {
   new_space_.LowerInlineAllocationLimit(
       new_space_.inline_allocation_limit_step());
 
+  FreeDeadArrayBuffers(true);
+
   // Update how much has survived scavenge.
   IncrementYoungSurvivorsCounter(static_cast<int>(
       (PromotedSpaceSizeOfObjects() - survived_watermark) + new_space_.Size()));
@@ -1797,46 +1801,118 @@ void Heap::ProcessNativeContexts(WeakObjectRetainer* retainer) {
 }
 
 
-void Heap::RegisterNewArrayBuffer(void* data, size_t length) {
+void Heap::RegisterNewArrayBufferHelper(std::map<void*, size_t>& live_buffers,
+                                        void* data, size_t length) {
+  live_buffers[data] = length;
+}
+
+
+void Heap::UnregisterArrayBufferHelper(
+    std::map<void*, size_t>& live_buffers,
+    std::map<void*, size_t>& not_yet_discovered_buffers, void* data) {
+  DCHECK(live_buffers.count(data) > 0);
+  live_buffers.erase(data);
+  not_yet_discovered_buffers.erase(data);
+}
+
+
+void Heap::RegisterLiveArrayBufferHelper(
+    std::map<void*, size_t>& not_yet_discovered_buffers, void* data) {
+  not_yet_discovered_buffers.erase(data);
+}
+
+
+size_t Heap::FreeDeadArrayBuffersHelper(
+    Isolate* isolate, std::map<void*, size_t>& live_buffers,
+    std::map<void*, size_t>& not_yet_discovered_buffers) {
+  size_t freed_memory = 0;
+  for (auto buffer = not_yet_discovered_buffers.begin();
+       buffer != not_yet_discovered_buffers.end(); ++buffer) {
+    isolate->array_buffer_allocator()->Free(buffer->first, buffer->second);
+    freed_memory += buffer->second;
+    live_buffers.erase(buffer->first);
+  }
+  not_yet_discovered_buffers = live_buffers;
+  return freed_memory;
+}
+
+
+void Heap::TearDownArrayBuffersHelper(
+    Isolate* isolate, std::map<void*, size_t>& live_buffers,
+    std::map<void*, size_t>& not_yet_discovered_buffers) {
+  for (auto buffer = live_buffers.begin(); buffer != live_buffers.end();
+       ++buffer) {
+    isolate->array_buffer_allocator()->Free(buffer->first, buffer->second);
+  }
+  live_buffers.clear();
+  not_yet_discovered_buffers.clear();
+}
+
+
+void Heap::RegisterNewArrayBuffer(bool in_new_space, void* data,
+                                  size_t length) {
   if (!data) return;
-  live_array_buffers_[data] = length;
+  RegisterNewArrayBufferHelper(
+      in_new_space ? live_new_array_buffers_ : live_array_buffers_, data,
+      length);
   reinterpret_cast<v8::Isolate*>(isolate_)
       ->AdjustAmountOfExternalAllocatedMemory(length);
 }
 
 
-void Heap::UnregisterArrayBuffer(void* data) {
+void Heap::UnregisterArrayBuffer(bool in_new_space, void* data) {
   if (!data) return;
-  DCHECK(live_array_buffers_.count(data) > 0);
-  live_array_buffers_.erase(data);
-  not_yet_discovered_array_buffers_.erase(data);
+  UnregisterArrayBufferHelper(
+      in_new_space ? live_new_array_buffers_ : live_array_buffers_,
+      in_new_space ? not_yet_discovered_new_array_buffers_
+                   : not_yet_discovered_array_buffers_,
+      data);
 }
 
 
-void Heap::RegisterLiveArrayBuffer(void* data) {
-  not_yet_discovered_array_buffers_.erase(data);
+void Heap::RegisterLiveArrayBuffer(bool in_new_space, void* data) {
+  RegisterLiveArrayBufferHelper(in_new_space
+                                    ? not_yet_discovered_new_array_buffers_
+                                    : not_yet_discovered_array_buffers_,
+                                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);
+void Heap::FreeDeadArrayBuffers(bool in_new_space) {
+  size_t freed_memory = FreeDeadArrayBuffersHelper(
+      isolate_, in_new_space ? live_new_array_buffers_ : live_array_buffers_,
+      in_new_space ? not_yet_discovered_new_array_buffers_
+                   : not_yet_discovered_array_buffers_);
+  if (freed_memory) {
+    reinterpret_cast<v8::Isolate*>(isolate_)
+        ->AdjustAmountOfExternalAllocatedMemory(
+            -static_cast<int64_t>(freed_memory));
   }
-  not_yet_discovered_array_buffers_ = live_array_buffers_;
 }
 
 
 void Heap::TearDownArrayBuffers() {
-  for (auto buffer = live_array_buffers_.begin();
-       buffer != live_array_buffers_.end(); ++buffer) {
-    isolate_->array_buffer_allocator()->Free(buffer->first, buffer->second);
+  TearDownArrayBuffersHelper(isolate_, live_array_buffers_,
+                             not_yet_discovered_array_buffers_);
+  TearDownArrayBuffersHelper(isolate_, live_new_array_buffers_,
+                             not_yet_discovered_new_array_buffers_);
 }
-  live_array_buffers_.clear();
-  not_yet_discovered_array_buffers_.clear();
+
+
+void Heap::PrepareArrayBufferDiscoveryInNewSpace() {
+  not_yet_discovered_new_array_buffers_ = live_new_array_buffers_;
+}
+
+
+void Heap::PromoteArrayBuffer(Object* obj) {
+  JSArrayBuffer* buffer = JSArrayBuffer::cast(obj);
+  if (buffer->is_external()) return;
+  void* data = buffer->backing_store();
+  if (!data) return;
+  DCHECK(live_new_array_buffers_.count(data) > 0);
+  live_array_buffers_[data] = live_new_array_buffers_[data];
+  live_new_array_buffers_.erase(data);
+  not_yet_discovered_new_array_buffers_.erase(data);
 }
 
 
@@ -2089,6 +2165,7 @@ class ScavengingVisitor : public StaticVisitorBase {
     table_.Register(kVisitFixedDoubleArray, &EvacuateFixedDoubleArray);
     table_.Register(kVisitFixedTypedArray, &EvacuateFixedTypedArray);
     table_.Register(kVisitFixedFloat64Array, &EvacuateFixedFloat64Array);
+    table_.Register(kVisitJSArrayBuffer, &EvacuateJSArrayBuffer);
 
     table_.Register(
         kVisitNativeContext,
@@ -2118,9 +2195,6 @@ class ScavengingVisitor : public StaticVisitorBase {
     table_.Register(kVisitJSWeakCollection,
                     &ObjectEvacuationStrategy<POINTER_OBJECT>::Visit);
 
-    table_.Register(kVisitJSArrayBuffer,
-                    &ObjectEvacuationStrategy<POINTER_OBJECT>::Visit);
-
     table_.Register(kVisitJSTypedArray,
                     &ObjectEvacuationStrategy<POINTER_OBJECT>::Visit);
 
@@ -2348,6 +2422,18 @@ class ScavengingVisitor : public StaticVisitorBase {
   }
 
 
+  static inline void EvacuateJSArrayBuffer(Map* map, HeapObject** slot,
+                                           HeapObject* object) {
+    ObjectEvacuationStrategy<POINTER_OBJECT>::Visit(map, slot, object);
+
+    Heap* heap = map->GetHeap();
+    MapWord map_word = object->map_word();
+    DCHECK(map_word.IsForwardingAddress());
+    HeapObject* target = map_word.ToForwardingAddress();
+    if (!heap->InNewSpace(target)) heap->PromoteArrayBuffer(target);
+  }
+
+
   static inline void EvacuateByteArray(Map* map, HeapObject** slot,
                                        HeapObject* object) {
     int object_size = reinterpret_cast<ByteArray*>(object)->ByteArraySize();

src/heap/heap.h

@@ -1567,10 +1567,28 @@ 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();
+  // The following methods are used to track raw C++ pointers to externally
+  // allocated memory used as backing store in live array buffers.
+
+  // A new ArrayBuffer was created with |data| as backing store.
+  void RegisterNewArrayBuffer(bool in_new_space, void* data, size_t length);
+
+  // The backing store |data| is no longer owned by V8.
+  void UnregisterArrayBuffer(bool in_new_space, void* data);
+
+  // A live ArrayBuffer was discovered during marking/scavenge.
+  void RegisterLiveArrayBuffer(bool in_new_space, void* data);
+
+  // Frees all backing store pointers that weren't discovered in the previous
+  // marking or scavenge phase.
+  void FreeDeadArrayBuffers(bool in_new_space);
+
+  // Prepare for a new scavenge phase. A new marking phase is implicitly
+  // prepared by finishing the previous one.
+  void PrepareArrayBufferDiscoveryInNewSpace();
+
+  // An ArrayBuffer moved from new space to old space.
+  void PromoteArrayBuffer(Object* buffer);
 
  protected:
   // Methods made available to tests.
@@ -2074,9 +2092,24 @@ class Heap {
   // the old space.
   void EvaluateOldSpaceLocalPretenuring(uint64_t size_of_objects_before_gc);
 
-  // Called on heap tear-down.
+  // Called on heap tear-down. Frees all remaining ArrayBuffer backing stores.
   void TearDownArrayBuffers();
 
+  // These correspond to the non-Helper versions.
+  void RegisterNewArrayBufferHelper(std::map<void*, size_t>& live_buffers,
+                                    void* data, size_t length);
+  void UnregisterArrayBufferHelper(
+      std::map<void*, size_t>& live_buffers,
+      std::map<void*, size_t>& not_yet_discovered_buffers, void* data);
+  void RegisterLiveArrayBufferHelper(
+      std::map<void*, size_t>& not_yet_discovered_buffers, void* data);
+  size_t FreeDeadArrayBuffersHelper(
+      Isolate* isolate, std::map<void*, size_t>& live_buffers,
+      std::map<void*, size_t>& not_yet_discovered_buffers);
+  void TearDownArrayBuffersHelper(
+      Isolate* isolate, std::map<void*, size_t>& live_buffers,
+      std::map<void*, size_t>& not_yet_discovered_buffers);
+
   // Record statistics before and after garbage collection.
   void ReportStatisticsBeforeGC();
   void ReportStatisticsAfterGC();
@@ -2319,7 +2352,9 @@ class Heap {
   bool concurrent_sweeping_enabled_;
 
   std::map<void*, size_t> live_array_buffers_;
+  std::map<void*, size_t> live_new_array_buffers_;
   std::map<void*, size_t> not_yet_discovered_array_buffers_;
+  std::map<void*, size_t> not_yet_discovered_new_array_buffers_;
 
   struct StrongRootsList;
   StrongRootsList* strong_roots_list_;

src/heap/mark-compact.cc

@@ -3041,6 +3041,10 @@ bool MarkCompactCollector::TryPromoteObject(HeapObject* object,
   AllocationResult allocation = old_space->AllocateRaw(object_size, alignment);
   if (allocation.To(&target)) {
     MigrateObject(target, object, object_size, old_space->identity());
+    // If we end up needing more special cases, we should factor this out.
+    if (V8_UNLIKELY(target->IsJSArrayBuffer())) {
+      heap()->PromoteArrayBuffer(target);
+    }
     heap()->IncrementPromotedObjectsSize(object_size);
     return true;
   }
@@ -4367,7 +4371,6 @@ void MarkCompactCollector::SweepSpaces() {
 #ifdef DEBUG
   state_ = SWEEP_SPACES;
 #endif
-  heap()->FreeDeadArrayBuffers();
 
   MoveEvacuationCandidatesToEndOfPagesList();
 
@@ -4395,6 +4398,8 @@ void MarkCompactCollector::SweepSpaces() {
 
   EvacuateNewSpaceAndCandidates();
 
+  heap()->FreeDeadArrayBuffers(false);
+
   // ClearNonLiveReferences depends on precise sweeping of map space to
   // detect whether unmarked map became dead in this collection or in one
   // of the previous ones.

src/heap/objects-visiting-inl.h

@@ -85,6 +85,10 @@ int StaticNewSpaceVisitor<StaticVisitor>::VisitJSArrayBuffer(
       heap,
       HeapObject::RawField(object, JSArrayBuffer::BodyDescriptor::kStartOffset),
       HeapObject::RawField(object, JSArrayBuffer::kSizeWithInternalFields));
+  if (!JSArrayBuffer::cast(object)->is_external()) {
+    heap->RegisterLiveArrayBuffer(true,
+                                  JSArrayBuffer::cast(object)->backing_store());
+  }
   return JSArrayBuffer::kSizeWithInternalFields;
 }
 
@@ -504,7 +508,8 @@ void StaticMarkingVisitor<StaticVisitor>::VisitJSArrayBuffer(
       HeapObject::RawField(object, JSArrayBuffer::BodyDescriptor::kStartOffset),
       HeapObject::RawField(object, JSArrayBuffer::kSizeWithInternalFields));
   if (!JSArrayBuffer::cast(object)->is_external()) {
-    heap->RegisterLiveArrayBuffer(JSArrayBuffer::cast(object)->backing_store());
+    heap->RegisterLiveArrayBuffer(heap->InNewSpace(object),
+                                  JSArrayBuffer::cast(object)->backing_store());
   }
 }
 

src/objects.cc

@@ -16481,7 +16481,8 @@ Handle<JSArrayBuffer> JSTypedArray::MaterializeArrayBuffer(
   void* backing_store =
       isolate->array_buffer_allocator()->AllocateUninitialized(
           fixed_typed_array->DataSize());
-  isolate->heap()->RegisterNewArrayBuffer(backing_store,
+  isolate->heap()->RegisterNewArrayBuffer(isolate->heap()->InNewSpace(*buffer),
+                                          backing_store,
                                           fixed_typed_array->DataSize());
   buffer->set_backing_store(backing_store);
   buffer->set_is_external(false);

src/runtime/runtime-typedarray.cc

@@ -34,7 +34,8 @@ void Runtime::SetupArrayBuffer(Isolate* isolate,
   array_buffer->set_byte_length(*byte_length);
 
   if (data && !is_external) {
-    isolate->heap()->RegisterNewArrayBuffer(data, allocated_length);
+    isolate->heap()->RegisterNewArrayBuffer(
+        isolate->heap()->InNewSpace(*array_buffer), data, allocated_length);
   }
 }
 
@@ -150,7 +151,8 @@ 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->heap()->UnregisterArrayBuffer(
+      isolate->heap()->InNewSpace(*array_buffer), backing_store);
   isolate->array_buffer_allocator()->Free(backing_store, byte_length);
   return isolate->heap()->undefined_value();
 }