Simple BlinkGC heap compaction.

third_party/WebKit/Source/platform/heap/InlinedGlobalMarkingVisitor.h

Index: third_party/WebKit/Source/platform/heap/InlinedGlobalMarkingVisitor.h
diff --git a/third_party/WebKit/Source/platform/heap/InlinedGlobalMarkingVisitor.h b/third_party/WebKit/Source/platform/heap/InlinedGlobalMarkingVisitor.h
index cfe134730d90e5f26d6f899c7ed14f3a13edf67c..5f10556eb7376e8caeaca72f5d71c3ae2cc19fbb 100644
--- a/third_party/WebKit/Source/platform/heap/InlinedGlobalMarkingVisitor.h
+++ b/third_party/WebKit/Source/platform/heap/InlinedGlobalMarkingVisitor.h
@@ -18,8 +18,9 @@ class InlinedGlobalMarkingVisitor final
   friend class MarkingVisitorImpl<InlinedGlobalMarkingVisitor>;
   using Impl = MarkingVisitorImpl<InlinedGlobalMarkingVisitor>;
 
-  explicit InlinedGlobalMarkingVisitor(ThreadState* state)
-      : VisitorHelper(state) {}
+  InlinedGlobalMarkingVisitor(ThreadState* state,
+                              Visitor::MarkingMode markingMode)
+      : VisitorHelper(state), m_markingMode(markingMode) {}
 
   // Hack to unify interface to visitor->trace().
   // Without this hack, we need to use visitor.trace() for
@@ -54,14 +55,14 @@ class InlinedGlobalMarkingVisitor final
     return true;
   }
 
-  inline Visitor::MarkingMode getMarkingMode() const {
-    return Visitor::GlobalMarking;
-  }
+  inline Visitor::MarkingMode getMarkingMode() const { return m_markingMode; }
 
  private:
   static InlinedGlobalMarkingVisitor fromHelper(Helper* helper) {
     return *static_cast<InlinedGlobalMarkingVisitor*>(helper);
   }
+
+  const Visitor::MarkingMode m_markingMode;

[haraken, 2016/12/02 12:43:20]

Would you help me understand why you need to add this member whereas Visitor
already has m_markingMode?

[sof, 2016/12/04 14:55:38]

InlinedGlobalMarkingVisitor isn't a Visitor, and the marking mode is needed to
correctly implement MarkingVisitorImpl::registerMoving*().

[haraken, 2016/12/09 07:25:54]

Maybe can we move m_markingMode to VisitorHelper? Then we won't need to
duplicate m_markingMode in two classes.

[sof, 2016/12/09 21:44:03]

Possibly, but it's a more complex than that given that we also need to
accommodate MarkingVisitor<Mode> const-Mode visitors. I've added a TODO.

 };
 
 inline void GarbageCollectedMixin::trace(InlinedGlobalMarkingVisitor) {}