8031776: Remove the unnecessary enum GenRemSet::Name

Reviewed-by: stefank, tschatzl, jwilhelm

hotspot/src/share/vm/gc_implementation/g1/g1CollectorPolicy.cpp

@@ -318,7 +318,7 @@ G1CollectorPolicy::G1CollectorPolicy() :
 
 void G1CollectorPolicy::initialize_alignments() {
   _space_alignment = HeapRegion::GrainBytes;
-  size_t card_table_alignment = GenRemSet::max_alignment_constraint(GenRemSet::CardTable);
+  size_t card_table_alignment = GenRemSet::max_alignment_constraint();
   size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
   _heap_alignment = MAX3(card_table_alignment, _space_alignment, page_size);
 }

hotspot/src/share/vm/memory/cardTableRS.hpp

@@ -105,8 +105,6 @@ public:
   ~CardTableRS();
 
   // *** GenRemSet functions.
-  GenRemSet::Name rs_kind() { return GenRemSet::CardTable; }
-
   CardTableRS* as_CardTableRS() { return this; }
 
   CardTableModRefBS* ct_bs() { return _ct_bs; }

hotspot/src/share/vm/memory/collectorPolicy.cpp

@@ -178,10 +178,7 @@ size_t CollectorPolicy::compute_heap_alignment() {
   // byte entry and the os page size is 4096, the maximum heap size should
   // be 512*4096 = 2MB aligned.
 
-  // There is only the GenRemSet in Hotspot and only the GenRemSet::CardTable
-  // is supported.
-  // Requirements of any new remembered set implementations must be added here.
-  size_t alignment = GenRemSet::max_alignment_constraint(GenRemSet::CardTable);
+  size_t alignment = GenRemSet::max_alignment_constraint();
 
   // Parallel GC does its own alignment of the generations to avoid requiring a
   // large page (256M on some platforms) for the permanent generation.  The

hotspot/src/share/vm/memory/defNewGeneration.cpp

@@ -61,7 +61,6 @@ bool DefNewGeneration::IsAliveClosure::do_object_b(oop p) {
 DefNewGeneration::KeepAliveClosure::
 KeepAliveClosure(ScanWeakRefClosure* cl) : _cl(cl) {
   GenRemSet* rs = GenCollectedHeap::heap()->rem_set();
-  assert(rs->rs_kind() == GenRemSet::CardTable, "Wrong rem set kind.");
   _rs = (CardTableRS*)rs;
 }
 

hotspot/src/share/vm/memory/genOopClosures.inline.hpp

@@ -45,7 +45,6 @@ inline void OopsInGenClosure::set_generation(Generation* gen) {
   // Barrier set for the heap, must be set after heap is initialized
   if (_rs == NULL) {
     GenRemSet* rs = SharedHeap::heap()->rem_set();
-    assert(rs->rs_kind() == GenRemSet::CardTable, "Wrong rem set kind");
     _rs = (CardTableRS*)rs;
   }
 }

hotspot/src/share/vm/memory/genRemSet.cpp

@@ -31,8 +31,7 @@
 // enumerate ref fields that have been modified (since the last
 // enumeration.)
 
-uintx GenRemSet::max_alignment_constraint(Name nm) {
-  assert(nm == GenRemSet::CardTable, "Unrecognized GenRemSet type.");
+uintx GenRemSet::max_alignment_constraint() {
   return CardTableRS::ct_max_alignment_constraint();
 }
 

hotspot/src/share/vm/memory/genRemSet.hpp

@@ -53,16 +53,9 @@ class GenRemSet: public CHeapObj<mtGC> {
   KlassRemSet _klass_rem_set;
 
 public:
-  enum Name {
-    CardTable,
-    Other
-  };
-
   GenRemSet(BarrierSet * bs) : _bs(bs) {}
   GenRemSet() : _bs(NULL) {}
 
-  virtual Name rs_kind() = 0;
-
   // These are for dynamic downcasts.  Unfortunately that it names the
   // possible subtypes (but not that they are subtypes!)  Return NULL if
   // the cast is invalide.
@@ -106,10 +99,9 @@ public:
   // within the heap, this function tells whether they are met.
   virtual bool is_aligned(HeapWord* addr) = 0;
 
-  // If the RS (or BS) imposes an aligment constraint on maximum heap size.
-  // (This must be static, and dispatch on "nm", because it is called
-  // before an RS is created.)
-  static uintx max_alignment_constraint(Name nm);
+  // Returns any alignment constraint that the remembered set imposes upon the
+  // heap.
+  static uintx max_alignment_constraint();
 
   virtual void verify() = 0;