8301459: Serial: Merge KeepAliveClosure into FastKeepAliveClosure

Reviewed-by: stefank, tschatzl

src/hotspot/share/gc/serial/defNewGeneration.cpp

@@ -76,18 +76,10 @@ bool DefNewGeneration::IsAliveClosure::do_object_b(oop p) {
   return cast_from_oop<HeapWord*>(p) >= _young_gen->reserved().end() || p->is_forwarded();
 }
 
-DefNewGeneration::KeepAliveClosure::
-KeepAliveClosure(ScanWeakRefClosure* cl) : _cl(cl) {
-  _rs = GenCollectedHeap::heap()->rem_set();
-}
-
-void DefNewGeneration::KeepAliveClosure::do_oop(oop* p)       { DefNewGeneration::KeepAliveClosure::do_oop_work(p); }
-void DefNewGeneration::KeepAliveClosure::do_oop(narrowOop* p) { DefNewGeneration::KeepAliveClosure::do_oop_work(p); }
-
-
 DefNewGeneration::FastKeepAliveClosure::
 FastKeepAliveClosure(DefNewGeneration* g, ScanWeakRefClosure* cl) :
-  DefNewGeneration::KeepAliveClosure(cl) {
+  _cl(cl) {
+  _rs = GenCollectedHeap::heap()->rem_set();
   _boundary = g->reserved().end();
 }
 

src/hotspot/share/gc/serial/defNewGeneration.hpp

@@ -167,19 +167,9 @@ protected:
     bool do_object_b(oop p);
   };
 
-  class KeepAliveClosure: public OopClosure {
+  class FastKeepAliveClosure: public OopClosure {
-  protected:
     ScanWeakRefClosure* _cl;
     CardTableRS* _rs;
-    template <class T> void do_oop_work(T* p);
-  public:
-    KeepAliveClosure(ScanWeakRefClosure* cl);
-    virtual void do_oop(oop* p);
-    virtual void do_oop(narrowOop* p);
-  };
-
-  class FastKeepAliveClosure: public KeepAliveClosure {
-  protected:
     HeapWord* _boundary;
     template <class T> void do_oop_work(T* p);
   public:

src/hotspot/share/gc/serial/defNewGeneration.inline.hpp

@@ -36,37 +36,6 @@
 
 // Methods of protected closure types
 
-template <class T>
-inline void DefNewGeneration::KeepAliveClosure::do_oop_work(T* p) {
-#ifdef ASSERT
-  {
-    // We never expect to see a null reference being processed
-    // as a weak reference.
-    oop obj = RawAccess<IS_NOT_NULL>::oop_load(p);
-    assert (oopDesc::is_oop(obj), "expected an oop while scanning weak refs");
-  }
-#endif // ASSERT
-
-  Devirtualizer::do_oop(_cl, p);
-
-  // Card marking is trickier for weak refs.
-  // This oop is a 'next' field which was filled in while we
-  // were discovering weak references. While we might not need
-  // to take a special action to keep this reference alive, we
-  // will need to dirty a card as the field was modified.
-  //
-  // Alternatively, we could create a method which iterates through
-  // each generation, allowing them in turn to examine the modified
-  // field.
-  //
-  // We could check that p is also in the old generation, but
-  // dirty cards in the young gen are never scanned, so the
-  // extra check probably isn't worthwhile.
-  if (GenCollectedHeap::heap()->is_in_reserved(p)) {
-    _rs->inline_write_ref_field_gc(p);
-  }
-}
-
 template <class T>
 inline void DefNewGeneration::FastKeepAliveClosure::do_oop_work(T* p) {
 #ifdef ASSERT