Introduce EmbedderReachableReferenceReporter

src/heap/heap.cc

Index: src/heap/heap.cc
diff --git a/src/heap/heap.cc b/src/heap/heap.cc
index 2472d45b7faf8eced8091f8205348530c80902b7..ce1c06b61eedcc3f022ca9dffaa11afff4b90e19 100644
--- a/src/heap/heap.cc
+++ b/src/heap/heap.cc
@@ -162,6 +162,8 @@ Heap::Heap()
       deserialization_complete_(false),
       strong_roots_list_(NULL),
       heap_iterator_depth_(0),
+      embedder_heap_tracer_(nullptr),
+      embedder_reference_reporter_(new TracePossibleWrapperReporter(this)),
       force_oom_(false) {
 // Allow build-time customization of the max semispace size. Building
 // V8 with snapshots and a non-default max semispace size is much
@@ -1615,7 +1617,7 @@ void Heap::Scavenge() {
     // Register found wrappers with embedder so it can add them to its marking
     // deque and correctly manage the case when v8 scavenger collects the
     // wrappers by either keeping wrappables alive, or cleaning marking deque.
-    mark_compact_collector()->RegisterWrappersWithEmbedderHeapTracer();
+    RegisterWrappersWithEmbedderHeapTracer();
   }
 
   // Flip the semispaces.  After flipping, to space is empty, from space has
@@ -4214,10 +4216,8 @@ void Heap::ReduceNewSpaceSize() {
 bool Heap::MarkingDequesAreEmpty() {
   return mark_compact_collector()->marking_deque()->IsEmpty() &&
          (!UsingEmbedderHeapTracer() ||
-          (mark_compact_collector()->wrappers_to_trace() == 0 &&
-           mark_compact_collector()
-                   ->embedder_heap_tracer()
-                   ->NumberOfWrappersToTrace() == 0));
+          (wrappers_to_trace() == 0 &&
+           embedder_heap_tracer()->NumberOfWrappersToTrace() == 0));
 }
 
 void Heap::FinalizeIncrementalMarkingIfComplete(
@@ -5561,15 +5561,36 @@ void Heap::NotifyDeserializationComplete() {
 }
 
 void Heap::SetEmbedderHeapTracer(EmbedderHeapTracer* tracer) {
-  mark_compact_collector()->SetEmbedderHeapTracer(tracer);
+  DCHECK_NOT_NULL(tracer);
+  CHECK_NULL(embedder_heap_tracer_);
+  embedder_heap_tracer_ = tracer;
 }
 
-bool Heap::UsingEmbedderHeapTracer() {
-  return mark_compact_collector()->UsingEmbedderHeapTracer();
+void Heap::RegisterWrappersWithEmbedderHeapTracer() {
+  DCHECK(UsingEmbedderHeapTracer());
+  if (wrappers_to_trace_.empty()) {
+    return;
+  }
+  embedder_heap_tracer()->RegisterV8References(wrappers_to_trace_);
+  wrappers_to_trace_.clear();
 }
 
 void Heap::TracePossibleWrapper(JSObject* js_object) {
-  mark_compact_collector()->TracePossibleWrapper(js_object);
+  DCHECK(js_object->WasConstructedFromApiFunction());
+  if (js_object->GetInternalFieldCount() >= 2 &&
+      js_object->GetInternalField(0) &&
+      js_object->GetInternalField(0) != undefined_value() &&
+      js_object->GetInternalField(1) != undefined_value()) {
+    DCHECK(reinterpret_cast<intptr_t>(js_object->GetInternalField(0)) % 2 == 0);
+    wrappers_to_trace_.push_back(std::pair<void*, void*>(
+        reinterpret_cast<void*>(js_object->GetInternalField(0)),
+        reinterpret_cast<void*>(js_object->GetInternalField(1))));
+  }
+}
+
+bool Heap::RequiresImmediateWrapperProcessing() {
+  const size_t kTooManyWrappers = 16000;
+  return wrappers_to_trace_.size() > kTooManyWrappers;
 }
 
 void Heap::RegisterExternallyReferencedObject(Object** object) {
@@ -5714,6 +5735,9 @@ void Heap::TearDown() {
 
   delete memory_allocator_;
   memory_allocator_ = nullptr;
+
+  delete embedder_reference_reporter_;
+  embedder_reference_reporter_ = nullptr;
 }