Use EmbedderHeapTracer instead of object grouping when trace_embedder_heap flag is set

src/heap/mark-compact.cc

Index: src/heap/mark-compact.cc
diff --git a/src/heap/mark-compact.cc b/src/heap/mark-compact.cc
index e537689c4a5ca4ba35530fc8d81a55f3bfd37596..914ea899053b31ce57477c2f7f67d893bbcb50d4 100644
--- a/src/heap/mark-compact.cc
+++ b/src/heap/mark-compact.cc
@@ -1961,7 +1961,6 @@ void MarkCompactCollector::ProcessMarkingDeque() {
   }
 }
 
-
 // Mark all objects reachable (transitively) from objects on the marking
 // stack including references only considered in the atomic marking pause.
 void MarkCompactCollector::ProcessEphemeralMarking(
@@ -1969,7 +1968,11 @@ void MarkCompactCollector::ProcessEphemeralMarking(
   bool work_to_do = true;
   DCHECK(marking_deque_.IsEmpty() && !marking_deque_.overflowed());
   while (work_to_do) {
-    if (!only_process_harmony_weak_collections) {
+    if (heap()->UsingEmbedderHeapTracer()) {
+      heap()->embedder_heap_tracer()->TraceWrappableFrom(
+          reinterpret_cast<v8::Isolate*>(isolate()), wrappers_to_trace_);
+      wrappers_to_trace_.clear();
+    } else if (!only_process_harmony_weak_collections) {
       isolate()->global_handles()->IterateObjectGroups(
           visitor, &IsUnmarkedHeapObjectWithHeap);
       MarkImplicitRefGroups(&MarkCompactMarkingVisitor::MarkObject);
@@ -1980,7 +1983,6 @@ void MarkCompactCollector::ProcessEphemeralMarking(
   }
 }
 
-
 void MarkCompactCollector::ProcessTopOptimizedFrame(ObjectVisitor* visitor) {
   for (StackFrameIterator it(isolate(), isolate()->thread_local_top());
        !it.done(); it.Advance()) {
@@ -2135,6 +2137,10 @@ void MarkCompactCollector::MarkLiveObjects() {
     {
       TRACE_GC(heap()->tracer(),
                GCTracer::Scope::MC_MARK_WEAK_CLOSURE_EPHEMERAL);
+      if (heap()->UsingEmbedderHeapTracer()) {

[Hannes Payer (out of office), 2016/04/07 20:38:31]

This piece of code and the code below need separate timer scopes.

[Marcel Hlopko, 2016/04/08 08:08:10]

Let's not make this method more complicated than it already is. We can do it
later if we'll need more precise numbers than what we have now.

+        heap()->embedder_heap_tracer()->TraceRoots(
+            reinterpret_cast<v8::Isolate*>(isolate()));
+      }
       ProcessEphemeralMarking(&root_visitor, false);
       ProcessMarkingDeque();
     }
@@ -2171,6 +2177,10 @@ void MarkCompactCollector::MarkLiveObjects() {
       TRACE_GC(heap()->tracer(), GCTracer::Scope::MC_MARK_WEAK_CLOSURE_HARMONY);
       ProcessEphemeralMarking(&root_visitor, true);
       ProcessMarkingDeque();
+      if (heap()->UsingEmbedderHeapTracer()) {
+        heap()->embedder_heap_tracer()->ClearTracingMarks(
+            reinterpret_cast<v8::Isolate*>(isolate()));
+      }
     }
   }