--- a/hotspot/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp	Tue Jun 24 15:50:50 2014 +0200
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp	Tue Sep 16 10:28:15 2014 +0200
@@ -1481,9 +1481,7 @@
 
       // Discard all rset updates
       JavaThread::dirty_card_queue_set().abandon_logs();
-      assert(!G1DeferredRSUpdate
-             || (G1DeferredRSUpdate &&
-                (dirty_card_queue_set().completed_buffers_num() == 0)), "Should not be any");
+      assert(dirty_card_queue_set().completed_buffers_num() == 0, "DCQS should be empty");
 
       _young_list->reset_sampled_info();
       // At this point there should be no regions in the
@@ -2094,15 +2092,13 @@
                                                 concurrent_g1_refine()->red_zone(),
                                                 Shared_DirtyCardQ_lock);
 
-  if (G1DeferredRSUpdate) {
-    dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
-                                      DirtyCardQ_CBL_mon,
-                                      DirtyCardQ_FL_lock,
-                                      -1, // never trigger processing
-                                      -1, // no limit on length
-                                      Shared_DirtyCardQ_lock,
-                                      &JavaThread::dirty_card_queue_set());
-  }
+  dirty_card_queue_set().initialize(NULL, // Should never be called by the Java code
+                                    DirtyCardQ_CBL_mon,
+                                    DirtyCardQ_FL_lock,
+                                    -1, // never trigger processing
+                                    -1, // no limit on length
+                                    Shared_DirtyCardQ_lock,
+                                    &JavaThread::dirty_card_queue_set());
 
   // Initialize the card queue set used to hold cards containing
   // references into the collection set.
@@ -5389,7 +5385,6 @@
 };
 
 void G1CollectedHeap::redirty_logged_cards() {
-  guarantee(G1DeferredRSUpdate, "Must only be called when using deferred RS updates.");
   double redirty_logged_cards_start = os::elapsedTime();
 
   uint n_workers = (G1CollectedHeap::use_parallel_gc_threads() ?
@@ -6049,9 +6044,7 @@
   // RSets.
   enqueue_discovered_references(n_workers);
 
-  if (G1DeferredRSUpdate) {
-    redirty_logged_cards();
-  }
+  redirty_logged_cards();
   COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
 }
 

--- a/hotspot/src/share/vm/gc_implementation/g1/g1EvacFailure.hpp	Tue Jun 24 15:50:50 2014 +0200
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1EvacFailure.hpp	Tue Sep 16 10:28:15 2014 +0200
@@ -176,15 +176,17 @@
 class RemoveSelfForwardPtrHRClosure: public HeapRegionClosure {
   G1CollectedHeap* _g1h;
   ConcurrentMark* _cm;
-  OopsInHeapRegionClosure *_update_rset_cl;
   uint _worker_id;
 
+  DirtyCardQueue _dcq;
+  UpdateRSetDeferred _update_rset_cl;
+
 public:
   RemoveSelfForwardPtrHRClosure(G1CollectedHeap* g1h,
-                                OopsInHeapRegionClosure* update_rset_cl,
                                 uint worker_id) :
-    _g1h(g1h), _update_rset_cl(update_rset_cl),
-    _worker_id(worker_id), _cm(_g1h->concurrent_mark()) { }
+    _g1h(g1h), _dcq(&g1h->dirty_card_queue_set()), _update_rset_cl(g1h, &_dcq),
+    _worker_id(worker_id), _cm(_g1h->concurrent_mark()) {
+    }
 
   bool doHeapRegion(HeapRegion *hr) {
     bool during_initial_mark = _g1h->g1_policy()->during_initial_mark_pause();
@@ -195,7 +197,7 @@
 
     if (hr->claimHeapRegion(HeapRegion::ParEvacFailureClaimValue)) {
       if (hr->evacuation_failed()) {
-        RemoveSelfForwardPtrObjClosure rspc(_g1h, _cm, hr, _update_rset_cl,
+        RemoveSelfForwardPtrObjClosure rspc(_g1h, _cm, hr, &_update_rset_cl,
                                             during_initial_mark,
                                             during_conc_mark,
                                             _worker_id);
@@ -214,7 +216,7 @@
         // whenever this might be required in the future.
         hr->rem_set()->reset_for_par_iteration();
         hr->reset_bot();
-        _update_rset_cl->set_region(hr);
+        _update_rset_cl.set_region(hr);
         hr->object_iterate(&rspc);
 
         hr->rem_set()->clean_strong_code_roots(hr);
@@ -238,16 +240,7 @@
     _g1h(g1h) { }
 
   void work(uint worker_id) {
-    UpdateRSetImmediate immediate_update(_g1h->g1_rem_set());
-    DirtyCardQueue dcq(&_g1h->dirty_card_queue_set());
-    UpdateRSetDeferred deferred_update(_g1h, &dcq);
-
-    OopsInHeapRegionClosure *update_rset_cl = &deferred_update;
-    if (!G1DeferredRSUpdate) {
-      update_rset_cl = &immediate_update;
-    }
-
-    RemoveSelfForwardPtrHRClosure rsfp_cl(_g1h, update_rset_cl, worker_id);
+    RemoveSelfForwardPtrHRClosure rsfp_cl(_g1h, worker_id);
 
     HeapRegion* hr = _g1h->start_cset_region_for_worker(worker_id);
     _g1h->collection_set_iterate_from(hr, &rsfp_cl);

--- a/hotspot/src/share/vm/gc_implementation/g1/g1GCPhaseTimes.cpp	Tue Jun 24 15:50:50 2014 +0200
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1GCPhaseTimes.cpp	Tue Sep 16 10:28:15 2014 +0200
@@ -237,10 +237,8 @@
   _last_gc_worker_times_ms.verify();
   _last_gc_worker_other_times_ms.verify();
 
-  if (G1DeferredRSUpdate) {
-    _last_redirty_logged_cards_time_ms.verify();
-    _last_redirty_logged_cards_processed_cards.verify();
-  }
+  _last_redirty_logged_cards_time_ms.verify();
+  _last_redirty_logged_cards_processed_cards.verify();
 }
 
 void G1GCPhaseTimes::note_string_dedup_fixup_start() {
@@ -352,12 +350,10 @@
     _recorded_non_young_cset_choice_time_ms));
   print_stats(2, "Ref Proc", _cur_ref_proc_time_ms);
   print_stats(2, "Ref Enq", _cur_ref_enq_time_ms);
-  if (G1DeferredRSUpdate) {
-    print_stats(2, "Redirty Cards", _recorded_redirty_logged_cards_time_ms);
-    if (G1Log::finest()) {
-      _last_redirty_logged_cards_time_ms.print(3, "Parallel Redirty");
-      _last_redirty_logged_cards_processed_cards.print(3, "Redirtied Cards");
-    }
+  print_stats(2, "Redirty Cards", _recorded_redirty_logged_cards_time_ms);
+  if (G1Log::finest()) {
+    _last_redirty_logged_cards_time_ms.print(3, "Parallel Redirty");
+    _last_redirty_logged_cards_processed_cards.print(3, "Redirtied Cards");
   }
   if (G1ReclaimDeadHumongousObjectsAtYoungGC) {
     print_stats(2, "Humongous Reclaim", _cur_fast_reclaim_humongous_time_ms);

--- a/hotspot/src/share/vm/gc_implementation/g1/g1ParScanThreadState.hpp	Tue Jun 24 15:50:50 2014 +0200
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1ParScanThreadState.hpp	Tue Sep 16 10:28:15 2014 +0200
@@ -84,20 +84,6 @@
   DirtyCardQueue& dirty_card_queue()             { return _dcq;  }
   G1SATBCardTableModRefBS* ctbs()                { return _ct_bs; }
 
-  template <class T> inline void immediate_rs_update(HeapRegion* from, T* p, int tid);
-
-  template <class T> void deferred_rs_update(HeapRegion* from, T* p, int tid) {
-    // If the new value of the field points to the same region or
-    // is the to-space, we don't need to include it in the Rset updates.
-    if (!from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) && !from->is_survivor()) {
-      size_t card_index = ctbs()->index_for(p);
-      // If the card hasn't been added to the buffer, do it.
-      if (ctbs()->mark_card_deferred(card_index)) {
-        dirty_card_queue().enqueue((jbyte*)ctbs()->byte_for_index(card_index));
-      }
-    }
-  }
-
  public:
   G1ParScanThreadState(G1CollectedHeap* g1h, uint queue_num, ReferenceProcessor* rp);
   ~G1ParScanThreadState();
@@ -124,8 +110,17 @@
     _refs->push(ref);
   }
 
-  template <class T> inline void update_rs(HeapRegion* from, T* p, int tid);
-
+  template <class T> void update_rs(HeapRegion* from, T* p, int tid) {
+    // If the new value of the field points to the same region or
+    // is the to-space, we don't need to include it in the Rset updates.
+    if (!from->is_in_reserved(oopDesc::load_decode_heap_oop(p)) && !from->is_survivor()) {
+      size_t card_index = ctbs()->index_for(p);
+      // If the card hasn't been added to the buffer, do it.
+      if (ctbs()->mark_card_deferred(card_index)) {
+        dirty_card_queue().enqueue((jbyte*)ctbs()->byte_for_index(card_index));
+      }
+    }
+  }
  private:
 
   inline HeapWord* allocate(GCAllocPurpose purpose, size_t word_sz);

--- a/hotspot/src/share/vm/gc_implementation/g1/g1ParScanThreadState.inline.hpp	Tue Jun 24 15:50:50 2014 +0200
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1ParScanThreadState.inline.hpp	Tue Sep 16 10:28:15 2014 +0200
@@ -29,20 +29,6 @@
 #include "gc_implementation/g1/g1RemSet.inline.hpp"
 #include "oops/oop.inline.hpp"
 
-template <class T> inline void G1ParScanThreadState::immediate_rs_update(HeapRegion* from, T* p, int tid) {
-  if (!from->is_survivor()) {
-    _g1_rem->par_write_ref(from, p, tid);
-  }
-}
-
-template <class T> void G1ParScanThreadState::update_rs(HeapRegion* from, T* p, int tid) {
-  if (G1DeferredRSUpdate) {
-    deferred_rs_update(from, p, tid);
-  } else {
-    immediate_rs_update(from, p, tid);
-  }
-}
-
 template <class T> void G1ParScanThreadState::do_oop_evac(T* p, HeapRegion* from) {
   assert(!oopDesc::is_null(oopDesc::load_decode_heap_oop(p)),
          "Reference should not be NULL here as such are never pushed to the task queue.");

--- a/hotspot/src/share/vm/gc_implementation/g1/g1RemSet.cpp	Tue Jun 24 15:50:50 2014 +0200
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1RemSet.cpp	Tue Sep 16 10:28:15 2014 +0200
@@ -339,12 +339,8 @@
   // are just discarded (there's no need to update the RSets of regions
   // that were in the collection set - after the pause these regions
   // are wholly 'free' of live objects. In the event of an evacuation
-  // failure the cards/buffers in this queue set are:
-  // * passed to the DirtyCardQueueSet that is used to manage deferred
-  //   RSet updates, or
-  // * scanned for references that point into the collection set
-  //   and the RSet of the corresponding region in the collection set
-  //   is updated immediately.
+  // failure the cards/buffers in this queue set are passed to the
+  // DirtyCardQueueSet that is used to manage RSet updates
   DirtyCardQueue into_cset_dcq(&_g1->into_cset_dirty_card_queue_set());
 
   assert((ParallelGCThreads > 0) || worker_i == 0, "invariant");
@@ -358,7 +354,6 @@
 
 void G1RemSet::prepare_for_oops_into_collection_set_do() {
   cleanupHRRS();
-  ConcurrentG1Refine* cg1r = _g1->concurrent_g1_refine();
   _g1->set_refine_cte_cl_concurrency(false);
   DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
   dcqs.concatenate_logs();
@@ -371,66 +366,6 @@
   _total_cards_scanned = 0;
 }
 
-
-// This closure, applied to a DirtyCardQueueSet, is used to immediately
-// update the RSets for the regions in the CSet. For each card it iterates
-// through the oops which coincide with that card. It scans the reference
-// fields in each oop; when it finds an oop that points into the collection
-// set, the RSet for the region containing the referenced object is updated.
-class UpdateRSetCardTableEntryIntoCSetClosure: public CardTableEntryClosure {
-  G1CollectedHeap* _g1;
-  CardTableModRefBS* _ct_bs;
-public:
-  UpdateRSetCardTableEntryIntoCSetClosure(G1CollectedHeap* g1,
-                                          CardTableModRefBS* bs):
-    _g1(g1), _ct_bs(bs)
-  { }
-
-  bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
-    // Construct the region representing the card.
-    HeapWord* start = _ct_bs->addr_for(card_ptr);
-    // And find the region containing it.
-    HeapRegion* r = _g1->heap_region_containing(start);
-
-    // Scan oops in the card looking for references into the collection set
-    // Don't use addr_for(card_ptr + 1) which can ask for
-    // a card beyond the heap.  This is not safe without a perm
-    // gen.
-    HeapWord* end   = start + CardTableModRefBS::card_size_in_words;
-    MemRegion scanRegion(start, end);
-
-    UpdateRSetImmediate update_rs_cl(_g1->g1_rem_set());
-    FilterIntoCSClosure update_rs_cset_oop_cl(NULL, _g1, &update_rs_cl);
-    FilterOutOfRegionClosure filter_then_update_rs_cset_oop_cl(r, &update_rs_cset_oop_cl);
-
-    // We can pass false as the "filter_young" parameter here as:
-    // * we should be in a STW pause,
-    // * the DCQS to which this closure is applied is used to hold
-    //   references that point into the collection set from the prior
-    //   RSet updating,
-    // * the post-write barrier shouldn't be logging updates to young
-    //   regions (but there is a situation where this can happen - see
-    //   the comment in G1RemSet::refine_card() below -
-    //   that should not be applicable here), and
-    // * during actual RSet updating, the filtering of cards in young
-    //   regions in HeapRegion::oops_on_card_seq_iterate_careful is
-    //   employed.
-    // As a result, when this closure is applied to "refs into cset"
-    // DCQS, we shouldn't see any cards in young regions.
-    update_rs_cl.set_region(r);
-    HeapWord* stop_point =
-      r->oops_on_card_seq_iterate_careful(scanRegion,
-                                          &filter_then_update_rs_cset_oop_cl,
-                                          false /* filter_young */,
-                                          NULL  /* card_ptr */);
-
-    // Since this is performed in the event of an evacuation failure, we
-    // we shouldn't see a non-null stop point
-    assert(stop_point == NULL, "saw an unallocated region");
-    return true;
-  }
-};
-
 void G1RemSet::cleanup_after_oops_into_collection_set_do() {
   guarantee( _cards_scanned != NULL, "invariant" );
   _total_cards_scanned = 0;
@@ -451,25 +386,10 @@
     double restore_remembered_set_start = os::elapsedTime();
 
     // Restore remembered sets for the regions pointing into the collection set.
-    if (G1DeferredRSUpdate) {
-      // If deferred RS updates are enabled then we just need to transfer
-      // the completed buffers from (a) the DirtyCardQueueSet used to hold
-      // cards that contain references that point into the collection set
-      // to (b) the DCQS used to hold the deferred RS updates
-      _g1->dirty_card_queue_set().merge_bufferlists(&into_cset_dcqs);
-    } else {
-
-      CardTableModRefBS* bs = (CardTableModRefBS*)_g1->barrier_set();
-      UpdateRSetCardTableEntryIntoCSetClosure update_rs_cset_immediate(_g1, bs);
-
-      int n_completed_buffers = 0;
-      while (into_cset_dcqs.apply_closure_to_completed_buffer(&update_rs_cset_immediate,
-                                                    0, 0, true)) {
-        n_completed_buffers++;
-      }
-      assert(n_completed_buffers == into_cset_n_buffers, "missed some buffers");
-    }
-
+    // We just need to transfer the completed buffers from the DirtyCardQueueSet
+    // used to hold cards that contain references that point into the collection set
+    // to the DCQS used to hold the deferred RS updates.
+    _g1->dirty_card_queue_set().merge_bufferlists(&into_cset_dcqs);
     _g1->g1_policy()->phase_times()->record_evac_fail_restore_remsets((os::elapsedTime() - restore_remembered_set_start) * 1000.0);
   }
 

--- a/hotspot/src/share/vm/gc_implementation/g1/g1RemSet.hpp	Tue Jun 24 15:50:50 2014 +0200
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1RemSet.hpp	Tue Sep 16 10:28:15 2014 +0200
@@ -193,18 +193,4 @@
   bool apply_to_weak_ref_discovered_field() { return true; }
 };
 
-class UpdateRSetImmediate: public OopsInHeapRegionClosure {
-private:
-  G1RemSet* _g1_rem_set;
-
-  template <class T> void do_oop_work(T* p);
-public:
-  UpdateRSetImmediate(G1RemSet* rs) :
-    _g1_rem_set(rs) {}
-
-  virtual void do_oop(narrowOop* p) { do_oop_work(p); }
-  virtual void do_oop(      oop* p) { do_oop_work(p); }
-};
-
-
 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1REMSET_HPP

--- a/hotspot/src/share/vm/gc_implementation/g1/g1RemSet.inline.hpp	Tue Jun 24 15:50:50 2014 +0200
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1RemSet.inline.hpp	Tue Sep 16 10:28:15 2014 +0200
@@ -79,13 +79,4 @@
   _rs->par_write_ref(_from, p, _worker_i);
 }
 
-template <class T>
-inline void UpdateRSetImmediate::do_oop_work(T* p) {
-  assert(_from->is_in_reserved(p), "paranoia");
-  T heap_oop = oopDesc::load_heap_oop(p);
-  if (!oopDesc::is_null(heap_oop) && !_from->is_survivor()) {
-    _g1_rem_set->par_write_ref(_from, p, 0);
-  }
-}
-
 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1REMSET_INLINE_HPP

--- a/hotspot/src/share/vm/gc_implementation/g1/g1_globals.hpp	Tue Jun 24 15:50:50 2014 +0200
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1_globals.hpp	Tue Sep 16 10:28:15 2014 +0200
@@ -108,9 +108,6 @@
   develop(bool, G1RSBarrierRegionFilter, true,                              \
           "If true, generate region filtering code in RS barrier")          \
                                                                             \
-  develop(bool, G1DeferredRSUpdate, true,                                   \
-          "If true, use deferred RS updates")                               \
-                                                                            \
   develop(bool, G1RSLogCheckCardTable, false,                               \
           "If true, verify that no dirty cards remain after RS log "        \
           "processing.")                                                    \

--- a/hotspot/test/gc/g1/TestDeferredRSUpdate.java	Tue Jun 24 15:50:50 2014 +0200
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,79 +0,0 @@
-/*
- * Copyright (c) 2014, 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
- * under the terms of the GNU General Public License version 2 only, as
- * published by the Free Software Foundation.
- *
- * This code is distributed in the hope that it will be useful, but WITHOUT
- * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
- * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
- * version 2 for more details (a copy is included in the LICENSE file that
- * accompanied this code).
- *
- * You should have received a copy of the GNU General Public License version
- * 2 along with this work; if not, write to the Free Software Foundation,
- * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
- *
- * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
- * or visit www.oracle.com if you need additional information or have any
- * questions.
- */
-
-/*
- * @test TestDeferredRSUpdate
- * @bug 8040977 8052170
- * @summary Ensure that running with -XX:-G1DeferredRSUpdate does not crash the VM
- * @key gc
- * @library /testlibrary
- */
-
-import com.oracle.java.testlibrary.ProcessTools;
-import com.oracle.java.testlibrary.OutputAnalyzer;
-
-public class TestDeferredRSUpdate {
-  public static void main(String[] args) throws Exception {
-    GCTest.main(args);
-
-    ProcessBuilder pb = ProcessTools.createJavaProcessBuilder("-XX:+UseG1GC",
-                                                              "-Xmx10M",
-                                                              "-XX:+PrintGCDetails",
-                                                              // G1DeferredRSUpdate is a develop option, but we cannot limit execution of this test to only debug VMs.
-                                                              "-XX:+IgnoreUnrecognizedVMOptions",
-                                                              "-XX:-G1DeferredRSUpdate",
-                                                              GCTest.class.getName());
-
-    OutputAnalyzer output = new OutputAnalyzer(pb.start());
-    output.shouldHaveExitValue(0);
-  }
-
-  static class GCTest {
-    private static Object[] garbage = new Object[32];
-
-    public static void main(String [] args) {
-      System.out.println("Creating garbage");
-      // Create 128MB of garbage. This should result in at least one minor GC, with
-      // some objects copied to old gen. As references from old to young are installed,
-      // the crash due to the use before initialize occurs.
-      Object prev = null;
-      Object prevPrev = null;
-      for (int i = 0; i < 1024; i++) {
-        Object[] next = new Object[32 * 1024];
-        next[0] = prev;
-        next[1] = prevPrev;
-
-        Object[] cur = (Object[]) garbage[i % garbage.length];
-        if (cur != null) {
-          cur[0] = null;
-          cur[1] = null;
-        }
-        garbage[i % garbage.length] = next;
-
-        prevPrev = prev;
-        prev = next;
-      }
-      System.out.println("Done");
-    }
-  }
-}