8233214: Remove runtime code not needed with CMS removed

Reviewed-by: shade, stefank, tschatzl

src/hotspot/share/classfile/classLoaderData.cpp

@@ -133,7 +133,7 @@ ClassLoaderData::ClassLoaderData(Handle h_class_loader, bool has_class_mirror_ho
   _metaspace_lock(new Mutex(Mutex::leaf+1, "Metaspace allocation lock", true,
                             Mutex::_safepoint_check_never)),
   _unloading(false), _has_class_mirror_holder(has_class_mirror_holder),
-  _modified_oops(true), _accumulated_modified_oops(false),
+  _modified_oops(true),
   // An unsafe anonymous class loader data doesn't have anything to keep
   // it from being unloaded during parsing of the unsafe anonymous class.
   // The null-class-loader should always be kept alive.

src/hotspot/share/classfile/classLoaderData.hpp

@@ -123,8 +123,7 @@ class ClassLoaderData : public CHeapObj<mtClass> {
                                  // to these class loader datas.
 
   // Remembered sets support for the oops in the class loader data.
-  bool _modified_oops;             // Card Table Equivalent (YC/CMS support)
-  bool _accumulated_modified_oops; // Mod Union Equivalent (CMS support)
+  bool _modified_oops;     // Card Table Equivalent
 
   int _keep_alive;         // if this CLD is kept alive.
                            // Used for non-strong hidden classes, unsafe anonymous classes and the
@@ -176,9 +175,6 @@ class ClassLoaderData : public CHeapObj<mtClass> {
   void record_modified_oops()            { _modified_oops = true; }
   bool has_modified_oops()               { return _modified_oops; }
 
-  void accumulate_modified_oops()        { if (has_modified_oops()) _accumulated_modified_oops = true; }
-  void clear_accumulated_modified_oops() { _accumulated_modified_oops = false; }
-  bool has_accumulated_modified_oops()   { return _accumulated_modified_oops; }
   oop holder_no_keepalive() const;
   oop holder_phantom() const;
 

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

@@ -115,9 +115,6 @@ void CLDScanClosure::do_cld(ClassLoaderData* cld) {
   // If the cld has not been dirtied we know that there's
   // no references into  the young gen and we can skip it.
   if (cld->has_modified_oops()) {
-    if (_accumulate_modified_oops) {
-      cld->accumulate_modified_oops();
-    }
 
     // Tell the closure which CLD is being scanned so that it can be dirtied
     // if oops are left pointing into the young gen.
@@ -567,8 +564,7 @@ void DefNewGeneration::collect(bool   full,
   DefNewScanClosure       scan_closure(this);
   DefNewYoungerGenClosure younger_gen_closure(this, _old_gen);
 
-  CLDScanClosure cld_scan_closure(&scan_closure,
-                                  heap->rem_set()->cld_rem_set()->accumulate_modified_oops());
+  CLDScanClosure cld_scan_closure(&scan_closure);
 
   set_promo_failure_scan_stack_closure(&scan_closure);
   FastEvacuateFollowersClosure evacuate_followers(heap,

src/hotspot/share/gc/shared/cardTableRS.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 2020, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -38,46 +38,6 @@
 #include "runtime/os.hpp"
 #include "utilities/macros.hpp"
 
-class HasAccumulatedModifiedOopsClosure : public CLDClosure {
-  bool _found;
- public:
-  HasAccumulatedModifiedOopsClosure() : _found(false) {}
-  void do_cld(ClassLoaderData* cld) {
-    if (_found) {
-      return;
-    }
-
-    if (cld->has_accumulated_modified_oops()) {
-      _found = true;
-    }
-  }
-  bool found() {
-    return _found;
-  }
-};
-
-bool CLDRemSet::mod_union_is_clear() {
-  HasAccumulatedModifiedOopsClosure closure;
-  ClassLoaderDataGraph::cld_do(&closure);
-
-  return !closure.found();
-}
-
-
-class ClearCLDModUnionClosure : public CLDClosure {
- public:
-  void do_cld(ClassLoaderData* cld) {
-    if (cld->has_accumulated_modified_oops()) {
-      cld->clear_accumulated_modified_oops();
-    }
-  }
-};
-
-void CLDRemSet::clear_mod_union() {
-  ClearCLDModUnionClosure closure;
-  ClassLoaderDataGraph::cld_do(&closure);
-}
-
 CardTable::CardValue CardTableRS::find_unused_youngergenP_card_value() {
   for (CardValue v = youngergenP1_card;
        v < cur_youngergen_and_prev_nonclean_card;

src/hotspot/share/gc/shared/cardTableRS.hpp

@@ -33,17 +33,6 @@ class DirtyCardToOopClosure;
 class Generation;
 class Space;
 
-// Helper to remember modified oops in all clds.
-class CLDRemSet {
-  bool _accumulate_modified_oops;
- public:
-  CLDRemSet() : _accumulate_modified_oops(false) {}
-  void set_accumulate_modified_oops(bool value) { _accumulate_modified_oops = value; }
-  bool accumulate_modified_oops() { return _accumulate_modified_oops; }
-  bool mod_union_is_clear();
-  void clear_mod_union();
-};
-
 // This RemSet uses a card table both as shared data structure
 // for a mod ref barrier set and for the rem set information.
 
@@ -53,8 +42,6 @@ class CardTableRS: public CardTable {
   friend class VerifyCTSpaceClosure;
   friend class ClearNoncleanCardWrapper;
 
-  CLDRemSet _cld_rem_set;
-
   void verify_space(Space* s, HeapWord* gen_start);
 
   enum ExtendedCardValue {
@@ -101,8 +88,6 @@ public:
   CardTableRS(MemRegion whole_heap, bool scanned_concurrently);
   ~CardTableRS();
 
-  CLDRemSet* cld_rem_set() { return &_cld_rem_set; }
-
   void younger_refs_in_space_iterate(Space* sp, HeapWord* gen_boundary, OopIterateClosure* cl, uint n_threads);
 
   virtual void verify_used_region_at_save_marks(Space* sp) const NOT_DEBUG_RETURN;

src/hotspot/share/gc/shared/genOopClosures.hpp

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2001, 2019, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2001, 2020, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -93,12 +93,9 @@ public:
 
 class CLDScanClosure: public CLDClosure {
   DefNewScanClosure* _scavenge_closure;
-  // true if the the modified oops state should be saved.
-  bool               _accumulate_modified_oops;
  public:
-  CLDScanClosure(DefNewScanClosure* scavenge_closure,
-                 bool accumulate_modified_oops) :
-       _scavenge_closure(scavenge_closure), _accumulate_modified_oops(accumulate_modified_oops) {}
+  CLDScanClosure(DefNewScanClosure* scavenge_closure) :
+       _scavenge_closure(scavenge_closure) {}
   void do_cld(ClassLoaderData* cld);
 };