--- a/src/hotspot/share/gc/shared/cardTableRS.cpp	Fri Jan 24 09:15:08 2020 +0100
+++ b/src/hotspot/share/gc/shared/cardTableRS.cpp	Fri Jan 24 09:24:46 2020 +0100
@@ -244,40 +244,6 @@
   }
 }
 
-// clean (by dirty->clean before) ==> cur_younger_gen
-// dirty                          ==> cur_youngergen_and_prev_nonclean_card
-// precleaned                     ==> cur_youngergen_and_prev_nonclean_card
-// prev-younger-gen               ==> cur_youngergen_and_prev_nonclean_card
-// cur-younger-gen                ==> cur_younger_gen
-// cur_youngergen_and_prev_nonclean_card ==> no change.
-void CardTableRS::write_ref_field_gc_par(void* field, oop new_val) {
-  volatile CardValue* entry = byte_for(field);
-  do {
-    CardValue entry_val = *entry;
-    // We put this first because it's probably the most common case.
-    if (entry_val == clean_card_val()) {
-      // No threat of contention with cleaning threads.
-      *entry = cur_youngergen_card_val();
-      return;
-    } else if (card_is_dirty_wrt_gen_iter(entry_val)
-               || is_prev_youngergen_card_val(entry_val)) {
-      // Mark it as both cur and prev youngergen; card cleaning thread will
-      // eventually remove the previous stuff.
-      CardValue new_val = cur_youngergen_and_prev_nonclean_card;
-      CardValue res = Atomic::cmpxchg(entry, entry_val, new_val);
-      // Did the CAS succeed?
-      if (res == entry_val) return;
-      // Otherwise, retry, to see the new value.
-      continue;
-    } else {
-      assert(entry_val == cur_youngergen_and_prev_nonclean_card
-             || entry_val == cur_youngergen_card_val(),
-             "should be only possibilities.");
-      return;
-    }
-  } while (true);
-}
-
 void CardTableRS::younger_refs_in_space_iterate(Space* sp,
                                                 OopsInGenClosure* cl,
                                                 uint n_threads) {

--- a/src/hotspot/share/gc/shared/cardTableRS.hpp	Fri Jan 24 09:15:08 2020 +0100
+++ b/src/hotspot/share/gc/shared/cardTableRS.hpp	Fri Jan 24 09:24:46 2020 +0100
@@ -124,11 +124,6 @@
     inline_write_ref_field_gc(field, new_val);
   }
 
-  // Override.  Might want to devirtualize this in the same fashion as
-  // above.  Ensures that the value of the card for field says that it's
-  // a younger card in the current collection.
-  virtual void write_ref_field_gc_par(void* field, oop new_val);
-
   bool is_aligned(HeapWord* addr) {
     return is_card_aligned(addr);
   }

--- a/src/hotspot/share/gc/shared/genOopClosures.hpp	Fri Jan 24 09:15:08 2020 +0100
+++ b/src/hotspot/share/gc/shared/genOopClosures.hpp	Fri Jan 24 09:24:46 2020 +0100
@@ -57,9 +57,6 @@
   // pointers must call the method below.
   template <class T> void do_barrier(T* p);
 
-  // Version for use by closures that may be called in parallel code.
-  template <class T> void par_do_barrier(T* p);
-
  public:
   OopsInGenClosure() : OopIterateClosure(NULL),
     _orig_gen(NULL), _gen(NULL), _gen_boundary(NULL), _rs(NULL) {};

--- a/src/hotspot/share/gc/shared/genOopClosures.inline.hpp	Fri Jan 24 09:15:08 2020 +0100
+++ b/src/hotspot/share/gc/shared/genOopClosures.inline.hpp	Fri Jan 24 09:24:46 2020 +0100
@@ -62,17 +62,6 @@
   }
 }
 
-template <class T> inline void OopsInGenClosure::par_do_barrier(T* p) {
-  assert(generation()->is_in_reserved(p), "expected ref in generation");
-  T heap_oop = RawAccess<>::oop_load(p);
-  assert(!CompressedOops::is_null(heap_oop), "expected non-null oop");
-  oop obj = CompressedOops::decode_not_null(heap_oop);
-  // If p points to a younger generation, mark the card.
-  if ((HeapWord*)obj < gen_boundary()) {
-    rs()->write_ref_field_gc_par(p, obj);
-  }
-}
-
 inline BasicOopsInGenClosure::BasicOopsInGenClosure(Generation* gen) : OopsInGenClosure(gen) {
 }