--- old/src/share/vm/gc_implementation/shenandoah/shenandoahOopClosures.hpp	2019-11-11 16:10:00.619342684 +0100
+++ new/src/share/vm/gc_implementation/shenandoah/shenandoahOopClosures.hpp	2019-11-11 16:10:00.538342688 +0100
@@ -24,11 +24,14 @@
 #ifndef SHARE_VM_GC_SHENANDOAH_SHENANDOAHOOPCLOSURES_HPP
 #define SHARE_VM_GC_SHENANDOAH_SHENANDOAHOOPCLOSURES_HPP
 
+#include "memory/iterator.hpp"
 #include "gc_implementation/shenandoah/shenandoahTaskqueue.hpp"
 
 class ShenandoahHeap;
 class ShenandoahStrDedupQueue;
 class ShenandoahMarkingContext;
+class ShenandoahTraversalGC;
+class OopClosure;
 
 enum UpdateRefsMode {
   NONE,       // No reference updating
@@ -200,4 +203,154 @@
   virtual void do_oop(oop* p)       { do_oop_nv(p); }
 };
 
+class ShenandoahTraversalSuperClosure : public MetadataAwareOopClosure {
+private:
+  ShenandoahTraversalGC* const _traversal_gc;
+  ShenandoahStrDedupQueue* const _dedup_queue;
+  Thread* const _thread;
+  ShenandoahObjToScanQueue* const _queue;
+  ShenandoahMarkingContext* const _mark_context;
+protected:
+  ShenandoahTraversalSuperClosure(ShenandoahObjToScanQueue* q, ReferenceProcessor* rp, ShenandoahStrDedupQueue* dq = NULL);
+
+  template <class T, bool STRING_DEDUP, bool DEGEN, bool ATOMIC_UPDATE>
+  void work(T* p);
+
+};
+
+class ShenandoahTraversalRootsClosure : public ShenandoahTraversalSuperClosure {
+private:
+  template <class T>
+  inline void do_oop_work(T* p)     { work<T, false, false, false>(p); }
+
+public:
+  ShenandoahTraversalRootsClosure(ShenandoahObjToScanQueue* q, ReferenceProcessor* rp) :
+    ShenandoahTraversalSuperClosure(q, rp) {}
+
+  virtual void do_oop(narrowOop* p) { do_oop_work(p); }
+  virtual void do_oop(oop* p)       { do_oop_work(p); }
+
+  virtual bool do_metadata()        { return false; }
+};
+
+class ShenandoahTraversalClosure : public ShenandoahTraversalSuperClosure {
+private:
+  template <class T>
+  inline void do_oop_work(T* p)     { work<T, false, false, true>(p); }
+
+public:
+  ShenandoahTraversalClosure(ShenandoahObjToScanQueue* q, ReferenceProcessor* rp) :
+    ShenandoahTraversalSuperClosure(q, rp) {}
+
+  virtual void do_oop(narrowOop* p) { do_oop_work(p); }
+  virtual void do_oop(oop* p)       { do_oop_work(p); }
+
+  virtual bool do_metadata()        { return false; }
+};
+
+class ShenandoahTraversalMetadataClosure : public ShenandoahTraversalSuperClosure {
+private:
+  template <class T>
+  inline void do_oop_work(T* p)     { work<T, false, false, true>(p); }
+
+public:
+  ShenandoahTraversalMetadataClosure(ShenandoahObjToScanQueue* q, ReferenceProcessor* rp) :
+    ShenandoahTraversalSuperClosure(q, rp) {}
+
+  virtual void do_oop(narrowOop* p) { do_oop_work(p); }
+  virtual void do_oop(oop* p)       { do_oop_work(p); }
+
+  virtual bool do_metadata()        { return true; }
+};
+
+class ShenandoahTraversalDedupClosure : public ShenandoahTraversalSuperClosure {
+private:
+  template <class T>
+  inline void do_oop_work(T* p)     { work<T, true, false, true>(p); }
+
+public:
+  ShenandoahTraversalDedupClosure(ShenandoahObjToScanQueue* q, ReferenceProcessor* rp, ShenandoahStrDedupQueue* dq) :
+    ShenandoahTraversalSuperClosure(q, rp, dq) {}
+
+  virtual void do_oop(narrowOop* p) { do_oop_work(p); }
+  virtual void do_oop(oop* p)       { do_oop_work(p); }
+
+  virtual bool do_metadata()        { return false; }
+};
+
+class ShenandoahTraversalMetadataDedupClosure : public ShenandoahTraversalSuperClosure {
+private:
+  template <class T>
+  inline void do_oop_work(T* p)     { work<T, true, false, true>(p); }
+
+public:
+  ShenandoahTraversalMetadataDedupClosure(ShenandoahObjToScanQueue* q, ReferenceProcessor* rp, ShenandoahStrDedupQueue* dq) :
+    ShenandoahTraversalSuperClosure(q, rp, dq) {}
+
+  virtual void do_oop(narrowOop* p) { do_oop_work(p); }
+  virtual void do_oop(oop* p)       { do_oop_work(p); }
+
+  virtual bool do_metadata()        { return true; }
+};
+
+class ShenandoahTraversalDegenClosure : public ShenandoahTraversalSuperClosure {
+private:
+  template <class T>
+  inline void do_oop_work(T* p)     { work<T, false, true, false>(p); }
+
+public:
+  ShenandoahTraversalDegenClosure(ShenandoahObjToScanQueue* q, ReferenceProcessor* rp) :
+    ShenandoahTraversalSuperClosure(q, rp) {}
+
+  virtual void do_oop(narrowOop* p) { do_oop_work(p); }
+  virtual void do_oop(oop* p)       { do_oop_work(p); }
+
+  virtual bool do_metadata()        { return false; }
+};
+
+class ShenandoahTraversalMetadataDegenClosure : public ShenandoahTraversalSuperClosure {
+private:
+  template <class T>
+  inline void do_oop_work(T* p)     { work<T, false, true, false>(p); }
+
+public:
+  ShenandoahTraversalMetadataDegenClosure(ShenandoahObjToScanQueue* q, ReferenceProcessor* rp) :
+    ShenandoahTraversalSuperClosure(q, rp) {}
+
+  virtual void do_oop(narrowOop* p) { do_oop_work(p); }
+  virtual void do_oop(oop* p)       { do_oop_work(p); }
+
+  virtual bool do_metadata()        { return true; }
+};
+
+class ShenandoahTraversalDedupDegenClosure : public ShenandoahTraversalSuperClosure {
+private:
+  template <class T>
+  inline void do_oop_work(T* p)     { work<T, true, true, false>(p); }
+
+public:
+  ShenandoahTraversalDedupDegenClosure(ShenandoahObjToScanQueue* q, ReferenceProcessor* rp, ShenandoahStrDedupQueue* dq) :
+    ShenandoahTraversalSuperClosure(q, rp, dq) {}
+
+  virtual void do_oop(narrowOop* p) { do_oop_work(p); }
+  virtual void do_oop(oop* p)       { do_oop_work(p); }
+
+  virtual bool do_metadata()        { return false; }
+};
+
+class ShenandoahTraversalMetadataDedupDegenClosure : public ShenandoahTraversalSuperClosure {
+private:
+  template <class T>
+  inline void do_oop_work(T* p)     { work<T, true, true, false>(p); }
+
+public:
+  ShenandoahTraversalMetadataDedupDegenClosure(ShenandoahObjToScanQueue* q, ReferenceProcessor* rp, ShenandoahStrDedupQueue* dq) :
+    ShenandoahTraversalSuperClosure(q, rp, dq) {}
+
+  virtual void do_oop(narrowOop* p) { do_oop_work(p); }
+  virtual void do_oop(oop* p)       { do_oop_work(p); }
+
+  virtual bool do_metadata()        { return true; }
+};
+
 #endif // SHARE_VM_GC_SHENANDOAH_SHENANDOAHOOPCLOSURES_HPP