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src/hotspot/share/gc/shenandoah/shenandoahVerifier.cpp

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*** 25,16 ***
--- 25,19 ---
  #include "precompiled.hpp"
  #include "gc/shared/tlab_globals.hpp"
  #include "gc/shenandoah/shenandoahAsserts.hpp"
  #include "gc/shenandoah/shenandoahForwarding.inline.hpp"
  #include "gc/shenandoah/shenandoahPhaseTimings.hpp"
+ #include "gc/shenandoah/shenandoahGeneration.hpp"
  #include "gc/shenandoah/shenandoahHeap.inline.hpp"
  #include "gc/shenandoah/shenandoahHeapRegion.inline.hpp"
+ #include "gc/shenandoah/shenandoahOldGeneration.hpp"
  #include "gc/shenandoah/shenandoahRootProcessor.hpp"
  #include "gc/shenandoah/shenandoahTaskqueue.inline.hpp"
  #include "gc/shenandoah/shenandoahUtils.hpp"
  #include "gc/shenandoah/shenandoahVerifier.hpp"
+ #include "gc/shenandoah/shenandoahYoungGeneration.hpp"
  #include "memory/allocation.hpp"
  #include "memory/iterator.inline.hpp"
  #include "memory/resourceArea.hpp"
  #include "oops/compressedOops.inline.hpp"
  #include "runtime/atomic.hpp"

*** 65,10 ***
--- 68,11 ---
    ShenandoahHeap* _heap;
    MarkBitMap* _map;
    ShenandoahLivenessData* _ld;
    void* _interior_loc;
    oop _loc;
+   ShenandoahGeneration* _generation;
  
  public:
    ShenandoahVerifyOopClosure(ShenandoahVerifierStack* stack, MarkBitMap* map, ShenandoahLivenessData* ld,
                               const char* phase, ShenandoahVerifier::VerifyOptions options) :
      _phase(phase),

*** 76,15 ***
      _stack(stack),
      _heap(ShenandoahHeap::heap()),
      _map(map),
      _ld(ld),
      _interior_loc(NULL),
!     _loc(NULL) {
      if (options._verify_marked == ShenandoahVerifier::_verify_marked_complete_except_references ||
          options._verify_marked == ShenandoahVerifier::_verify_marked_disable) {
        set_ref_discoverer_internal(new ShenandoahIgnoreReferenceDiscoverer());
      }
    }
  
  private:
    void check(ShenandoahAsserts::SafeLevel level, oop obj, bool test, const char* label) {
      if (!test) {
--- 80,21 ---
      _stack(stack),
      _heap(ShenandoahHeap::heap()),
      _map(map),
      _ld(ld),
      _interior_loc(NULL),
!     _loc(NULL),
+     _generation(NULL) {
      if (options._verify_marked == ShenandoahVerifier::_verify_marked_complete_except_references ||
          options._verify_marked == ShenandoahVerifier::_verify_marked_disable) {
        set_ref_discoverer_internal(new ShenandoahIgnoreReferenceDiscoverer());
      }
+ 
+     if (_heap->mode()->is_generational()) {
+       _generation = _heap->active_generation();
+       assert(_generation != NULL, "Expected active generation in this mode");
+     }
    }
  
  private:
    void check(ShenandoahAsserts::SafeLevel level, oop obj, bool test, const char* label) {
      if (!test) {

*** 104,39 ***
        // methods.
        //
        // For performance reasons, only fully verify non-marked field values.
        // We are here when the host object for *p is already marked.
  
!       if (_map->par_mark(obj)) {
          verify_oop_at(p, obj);
          _stack->push(ShenandoahVerifierTask(obj));
        }
      }
    }
  
    void verify_oop(oop obj) {
      // Perform consistency checks with gradually decreasing safety level. This guarantees
      // that failure report would not try to touch something that was not yet verified to be
      // safe to process.
  
      check(ShenandoahAsserts::_safe_unknown, obj, _heap->is_in(obj),
                "oop must be in heap");
      check(ShenandoahAsserts::_safe_unknown, obj, is_object_aligned(obj),
                "oop must be aligned");
  
!     ShenandoahHeapRegion *obj_reg = _heap->heap_region_containing(obj);
      Klass* obj_klass = obj->klass_or_null();
  
      // Verify that obj is not in dead space:
      {
        // Do this before touching obj->size()
        check(ShenandoahAsserts::_safe_unknown, obj, obj_klass != NULL,
               "Object klass pointer should not be NULL");
        check(ShenandoahAsserts::_safe_unknown, obj, Metaspace::contains(obj_klass),
               "Object klass pointer must go to metaspace");
  
!       HeapWord *obj_addr = cast_from_oop<HeapWord*>(obj);
        check(ShenandoahAsserts::_safe_unknown, obj, obj_addr < obj_reg->top(),
               "Object start should be within the region");
  
        if (!obj_reg->is_humongous()) {
          check(ShenandoahAsserts::_safe_unknown, obj, (obj_addr + obj->size()) <= obj_reg->top(),
--- 114,48 ---
        // methods.
        //
        // For performance reasons, only fully verify non-marked field values.
        // We are here when the host object for *p is already marked.
  
!       if ( in_generation(obj) && _map->par_mark(obj)) {
          verify_oop_at(p, obj);
          _stack->push(ShenandoahVerifierTask(obj));
        }
      }
    }
  
+   bool in_generation(oop obj) {
+     if (_generation == NULL) {
+       return true;
+     }
+ 
+     ShenandoahHeapRegion* region = _heap->heap_region_containing(obj);
+     return _generation->contains(region);
+   }
+ 
    void verify_oop(oop obj) {
      // Perform consistency checks with gradually decreasing safety level. This guarantees
      // that failure report would not try to touch something that was not yet verified to be
      // safe to process.
  
      check(ShenandoahAsserts::_safe_unknown, obj, _heap->is_in(obj),
                "oop must be in heap");
      check(ShenandoahAsserts::_safe_unknown, obj, is_object_aligned(obj),
                "oop must be aligned");
  
!     ShenandoahHeapRegion* obj_reg = _heap->heap_region_containing(obj);
      Klass* obj_klass = obj->klass_or_null();
  
      // Verify that obj is not in dead space:
      {
        // Do this before touching obj->size()
        check(ShenandoahAsserts::_safe_unknown, obj, obj_klass != NULL,
               "Object klass pointer should not be NULL");
        check(ShenandoahAsserts::_safe_unknown, obj, Metaspace::contains(obj_klass),
               "Object klass pointer must go to metaspace");
  
!       HeapWord* obj_addr = cast_from_oop<HeapWord*>(obj);
        check(ShenandoahAsserts::_safe_unknown, obj, obj_addr < obj_reg->top(),
               "Object start should be within the region");
  
        if (!obj_reg->is_humongous()) {
          check(ShenandoahAsserts::_safe_unknown, obj, (obj_addr + obj->size()) <= obj_reg->top(),

*** 161,11 ***
            break;
          case ShenandoahVerifier::_verify_liveness_complete:
            Atomic::add(&_ld[obj_reg->index()], (uint) obj->size(), memory_order_relaxed);
            // fallthrough for fast failure for un-live regions:
          case ShenandoahVerifier::_verify_liveness_conservative:
!           check(ShenandoahAsserts::_safe_oop, obj, obj_reg->has_live(),
                     "Object must belong to region with live data");
            break;
          default:
            assert(false, "Unhandled liveness verification");
        }
--- 180,12 ---
            break;
          case ShenandoahVerifier::_verify_liveness_complete:
            Atomic::add(&_ld[obj_reg->index()], (uint) obj->size(), memory_order_relaxed);
            // fallthrough for fast failure for un-live regions:
          case ShenandoahVerifier::_verify_liveness_conservative:
!           check(ShenandoahAsserts::_safe_oop, obj, obj_reg->has_live() ||
+                 (obj_reg->is_old() && ShenandoahHeap::heap()->is_gc_generation_young()),
                     "Object must belong to region with live data");
            break;
          default:
            assert(false, "Unhandled liveness verification");
        }

*** 196,11 ***
  
        // Verify that forwardee is not in the dead space:
        check(ShenandoahAsserts::_safe_oop, obj, !fwd_reg->is_humongous(),
               "Should have no humongous forwardees");
  
!       HeapWord *fwd_addr = cast_from_oop<HeapWord *>(fwd);
        check(ShenandoahAsserts::_safe_oop, obj, fwd_addr < fwd_reg->top(),
               "Forwardee start should be within the region");
        check(ShenandoahAsserts::_safe_oop, obj, (fwd_addr + fwd->size()) <= fwd_reg->top(),
               "Forwardee end should be within the region");
  
--- 216,11 ---
  
        // Verify that forwardee is not in the dead space:
        check(ShenandoahAsserts::_safe_oop, obj, !fwd_reg->is_humongous(),
               "Should have no humongous forwardees");
  
!       HeapWord* fwd_addr = cast_from_oop<HeapWord* >(fwd);
        check(ShenandoahAsserts::_safe_oop, obj, fwd_addr < fwd_reg->top(),
               "Forwardee start should be within the region");
        check(ShenandoahAsserts::_safe_oop, obj, (fwd_addr + fwd->size()) <= fwd_reg->top(),
               "Forwardee end should be within the region");
  

*** 210,25 ***
      } else {
        fwd_reg = obj_reg;
      }
  
      // ------------ obj and fwd are safe at this point --------------
! 
      switch (_options._verify_marked) {
        case ShenandoahVerifier::_verify_marked_disable:
          // skip
          break;
        case ShenandoahVerifier::_verify_marked_incomplete:
!         check(ShenandoahAsserts::_safe_all, obj, _heap->marking_context()->is_marked(obj),
                 "Must be marked in incomplete bitmap");
          break;
        case ShenandoahVerifier::_verify_marked_complete:
!         check(ShenandoahAsserts::_safe_all, obj, _heap->complete_marking_context()->is_marked(obj),
                 "Must be marked in complete bitmap");
          break;
        case ShenandoahVerifier::_verify_marked_complete_except_references:
!         check(ShenandoahAsserts::_safe_all, obj, _heap->complete_marking_context()->is_marked(obj),
                "Must be marked in complete bitmap, except j.l.r.Reference referents");
          break;
        default:
          assert(false, "Unhandled mark verification");
      }
--- 230,32 ---
      } else {
        fwd_reg = obj_reg;
      }
  
      // ------------ obj and fwd are safe at this point --------------
!     // We allow for marked or old here for two reasons:
+     //  1. If this is a young collect, old objects wouldn't be marked. We've
+     //     recently change the verifier traversal to only follow young objects
+     //     during a young collect so this _shouldn't_ be necessary.
+     //  2. At present, we do not clear dead objects from the remembered set.
+     //     Everything in the remembered set is old (ipso facto), so allowing for
+     //     'marked_or_old' covers the case of stale objects in rset.
+     // TODO: Just use 'is_marked' here.
      switch (_options._verify_marked) {
        case ShenandoahVerifier::_verify_marked_disable:
          // skip
          break;
        case ShenandoahVerifier::_verify_marked_incomplete:
!         check(ShenandoahAsserts::_safe_all, obj, _heap->marking_context()->is_marked_or_old(obj),
                 "Must be marked in incomplete bitmap");
          break;
        case ShenandoahVerifier::_verify_marked_complete:
!         check(ShenandoahAsserts::_safe_all, obj, _heap->complete_marking_context()->is_marked_or_old(obj),
                 "Must be marked in complete bitmap");
          break;
        case ShenandoahVerifier::_verify_marked_complete_except_references:
!         check(ShenandoahAsserts::_safe_all, obj, _heap->complete_marking_context()->is_marked_or_old(obj),
                "Must be marked in complete bitmap, except j.l.r.Reference referents");
          break;
        default:
          assert(false, "Unhandled mark verification");
      }

*** 318,19 ***
--- 345,59 ---
  public:
    ShenandoahCalculateRegionStatsClosure() : _used(0), _committed(0), _garbage(0) {};
  
    void heap_region_do(ShenandoahHeapRegion* r) {
      _used += r->used();
+     log_debug(gc)("ShenandoahCalculatRegionStatsClosure added " SIZE_FORMAT " for %s Region " SIZE_FORMAT ", yielding: " SIZE_FORMAT,
+                   r->used(), r->is_humongous()? "humongous": "regular", r->index(), _used);
      _garbage += r->garbage();
      _committed += r->is_committed() ? ShenandoahHeapRegion::region_size_bytes() : 0;
    }
  
    size_t used() { return _used; }
    size_t committed() { return _committed; }
    size_t garbage() { return _garbage; }
  };
  
+ class ShenandoahGenerationStatsClosure : public ShenandoahHeapRegionClosure {
+  public:
+   ShenandoahCalculateRegionStatsClosure old;
+   ShenandoahCalculateRegionStatsClosure young;
+   ShenandoahCalculateRegionStatsClosure global;
+ 
+   void heap_region_do(ShenandoahHeapRegion* r) override {
+     switch (r->affiliation()) {
+       default:
+         ShouldNotReachHere();
+         return;
+       case FREE: return;
+       case YOUNG_GENERATION:
+         young.heap_region_do(r);
+         break;
+       case OLD_GENERATION:
+         old.heap_region_do(r);
+         break;
+     }
+     global.heap_region_do(r);
+   }
+ 
+   static void log_usage(ShenandoahGeneration* generation, ShenandoahCalculateRegionStatsClosure& stats) {
+     log_debug(gc)("Safepoint verification: %s verified usage: " SIZE_FORMAT "%s, recorded usage: " SIZE_FORMAT "%s",
+                   generation->name(),
+                   byte_size_in_proper_unit(generation->used()), proper_unit_for_byte_size(generation->used()),
+                   byte_size_in_proper_unit(stats.used()), proper_unit_for_byte_size(stats.used()));
+   }
+ 
+   static void validate_usage(const char* label, ShenandoahGeneration* generation, ShenandoahCalculateRegionStatsClosure& stats) {
+     guarantee(stats.used() == generation->used(),
+               "%s: generation (%s) used size must be consistent: generation-used = " SIZE_FORMAT "%s, regions-used = " SIZE_FORMAT "%s",
+               label, generation->name(),
+               byte_size_in_proper_unit(generation->used()), proper_unit_for_byte_size(generation->used()),
+               byte_size_in_proper_unit(stats.used()), proper_unit_for_byte_size(stats.used()));
+   }
+ };
+ 
  class ShenandoahVerifyHeapRegionClosure : public ShenandoahHeapRegionClosure {
  private:
    ShenandoahHeap* _heap;
    const char* _phase;
    ShenandoahVerifier::VerifyRegions _regions;

*** 408,12 ***
             "TLAB alloc count should not be larger than capacity");
  
      verify(r, r->get_gclab_allocs() <= r->capacity(),
             "GCLAB alloc count should not be larger than capacity");
  
!     verify(r, r->get_shared_allocs() + r->get_tlab_allocs() + r->get_gclab_allocs() == r->used(),
!            "Accurate accounting: shared + TLAB + GCLAB = used");
  
      verify(r, !r->is_empty() || !r->has_live(),
             "Empty regions should not have live data");
  
      verify(r, r->is_cset() == _heap->collection_set()->is_in(r),
--- 475,15 ---
             "TLAB alloc count should not be larger than capacity");
  
      verify(r, r->get_gclab_allocs() <= r->capacity(),
             "GCLAB alloc count should not be larger than capacity");
  
!     verify(r, r->get_plab_allocs() <= r->capacity(),
!            "PLAB alloc count should not be larger than capacity");
+ 
+     verify(r, r->get_shared_allocs() + r->get_tlab_allocs() + r->get_gclab_allocs() + r->get_plab_allocs() == r->used(),
+            "Accurate accounting: shared + TLAB + GCLAB + PLAB = used");
  
      verify(r, !r->is_empty() || !r->has_live(),
             "Empty regions should not have live data");
  
      verify(r, r->is_cset() == _heap->collection_set()->is_in(r),

*** 486,15 ***
  
  class ShenandoahVerifierMarkedRegionTask : public AbstractGangTask {
  private:
    const char* _label;
    ShenandoahVerifier::VerifyOptions _options;
!   ShenandoahHeap *_heap;
    MarkBitMap* _bitmap;
    ShenandoahLivenessData* _ld;
    volatile size_t _claimed;
    volatile size_t _processed;
  
  public:
    ShenandoahVerifierMarkedRegionTask(MarkBitMap* bitmap,
                                       ShenandoahLivenessData* ld,
                                       const char* label,
--- 556,16 ---
  
  class ShenandoahVerifierMarkedRegionTask : public AbstractGangTask {
  private:
    const char* _label;
    ShenandoahVerifier::VerifyOptions _options;
!   ShenandoahHeap* _heap;
    MarkBitMap* _bitmap;
    ShenandoahLivenessData* _ld;
    volatile size_t _claimed;
    volatile size_t _processed;
+   ShenandoahGeneration* _generation;
  
  public:
    ShenandoahVerifierMarkedRegionTask(MarkBitMap* bitmap,
                                       ShenandoahLivenessData* ld,
                                       const char* label,

*** 504,11 ***
            _options(options),
            _heap(ShenandoahHeap::heap()),
            _bitmap(bitmap),
            _ld(ld),
            _claimed(0),
!           _processed(0) {};
  
    size_t processed() {
      return Atomic::load(&_processed);
    }
  
--- 575,17 ---
            _options(options),
            _heap(ShenandoahHeap::heap()),
            _bitmap(bitmap),
            _ld(ld),
            _claimed(0),
!           _processed(0),
+           _generation(NULL) {
+     if (_heap->mode()->is_generational()) {
+       _generation = _heap->active_generation();
+       assert(_generation != NULL, "Expected active generation in this mode.");
+     }
+   };
  
    size_t processed() {
      return Atomic::load(&_processed);
    }
  

*** 520,10 ***
--- 597,14 ---
  
      while (true) {
        size_t v = Atomic::fetch_and_add(&_claimed, 1u, memory_order_relaxed);
        if (v < _heap->num_regions()) {
          ShenandoahHeapRegion* r = _heap->get_region(v);
+         if (!in_generation(r)) {
+           continue;
+         }
+ 
          if (!r->is_humongous() && !r->is_trash()) {
            work_regular(r, stack, cl);
          } else if (r->is_humongous_start()) {
            work_humongous(r, stack, cl);
          }

*** 531,20 ***
          break;
        }
      }
    }
  
!   virtual void work_humongous(ShenandoahHeapRegion *r, ShenandoahVerifierStack& stack, ShenandoahVerifyOopClosure& cl) {
      size_t processed = 0;
      HeapWord* obj = r->bottom();
      if (_heap->complete_marking_context()->is_marked(cast_to_oop(obj))) {
        verify_and_follow(obj, stack, cl, &processed);
      }
      Atomic::add(&_processed, processed, memory_order_relaxed);
    }
  
!   virtual void work_regular(ShenandoahHeapRegion *r, ShenandoahVerifierStack &stack, ShenandoahVerifyOopClosure &cl) {
      size_t processed = 0;
      ShenandoahMarkingContext* ctx = _heap->complete_marking_context();
      HeapWord* tams = ctx->top_at_mark_start(r);
  
      // Bitmaps, before TAMS
--- 612,24 ---
          break;
        }
      }
    }
  
!   bool in_generation(ShenandoahHeapRegion* r) {
+     return _generation == NULL || _generation->contains(r);
+   }
+ 
+   virtual void work_humongous(ShenandoahHeapRegion* r, ShenandoahVerifierStack& stack, ShenandoahVerifyOopClosure& cl) {
      size_t processed = 0;
      HeapWord* obj = r->bottom();
      if (_heap->complete_marking_context()->is_marked(cast_to_oop(obj))) {
        verify_and_follow(obj, stack, cl, &processed);
      }
      Atomic::add(&_processed, processed, memory_order_relaxed);
    }
  
!   virtual void work_regular(ShenandoahHeapRegion* r, ShenandoahVerifierStack &stack, ShenandoahVerifyOopClosure &cl) {
      size_t processed = 0;
      ShenandoahMarkingContext* ctx = _heap->complete_marking_context();
      HeapWord* tams = ctx->top_at_mark_start(r);
  
      // Bitmaps, before TAMS

*** 573,11 ***
      }
  
      Atomic::add(&_processed, processed, memory_order_relaxed);
    }
  
!   void verify_and_follow(HeapWord *addr, ShenandoahVerifierStack &stack, ShenandoahVerifyOopClosure &cl, size_t *processed) {
      if (!_bitmap->par_mark(addr)) return;
  
      // Verify the object itself:
      oop obj = cast_to_oop(addr);
      cl.verify_oop_standalone(obj);
--- 658,11 ---
      }
  
      Atomic::add(&_processed, processed, memory_order_relaxed);
    }
  
!   void verify_and_follow(HeapWord* addr, ShenandoahVerifierStack &stack, ShenandoahVerifyOopClosure &cl, size_t* processed) {
      if (!_bitmap->par_mark(addr)) return;
  
      // Verify the object itself:
      oop obj = cast_to_oop(addr);
      cl.verify_oop_standalone(obj);

*** 603,17 ***
  
  public:
    VerifyThreadGCState(const char* label, char expected) : _label(label), _expected(expected) {}
    void do_thread(Thread* t) {
      char actual = ShenandoahThreadLocalData::gc_state(t);
!     if (actual != _expected) {
        fatal("%s: Thread %s: expected gc-state %d, actual %d", _label, t->name(), _expected, actual);
      }
    }
  };
  
! void ShenandoahVerifier::verify_at_safepoint(const char *label,
                                               VerifyForwarded forwarded, VerifyMarked marked,
                                               VerifyCollectionSet cset,
                                               VerifyLiveness liveness, VerifyRegions regions,
                                               VerifyGCState gcstate) {
    guarantee(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "only when nothing else happens");
--- 688,18 ---
  
  public:
    VerifyThreadGCState(const char* label, char expected) : _label(label), _expected(expected) {}
    void do_thread(Thread* t) {
      char actual = ShenandoahThreadLocalData::gc_state(t);
!     if (actual != _expected && !(actual & ShenandoahHeap::OLD_MARKING)) {
        fatal("%s: Thread %s: expected gc-state %d, actual %d", _label, t->name(), _expected, actual);
      }
    }
  };
  
! void ShenandoahVerifier::verify_at_safepoint(const char* label,
+                                              VerifyRememberedSet remembered,
                                               VerifyForwarded forwarded, VerifyMarked marked,
                                               VerifyCollectionSet cset,
                                               VerifyLiveness liveness, VerifyRegions regions,
                                               VerifyGCState gcstate) {
    guarantee(ShenandoahSafepoint::is_at_shenandoah_safepoint(), "only when nothing else happens");

*** 642,10 ***
--- 728,14 ---
          if (!_heap->is_stw_gc_in_progress()) {
            // Only concurrent GC sets this.
            expected |= ShenandoahHeap::WEAK_ROOTS;
          }
          break;
+       case _verify_gcstate_updating:
+         enabled = true;
+         expected = ShenandoahHeap::HAS_FORWARDED | ShenandoahHeap::UPDATEREFS;
+         break;
        case _verify_gcstate_stable:
          enabled = true;
          expected = ShenandoahHeap::STABLE;
          break;
        case _verify_gcstate_stable_weakroots:

*** 661,11 ***
          assert(false, "Unhandled gc-state verification");
      }
  
      if (enabled) {
        char actual = _heap->gc_state();
!       if (actual != expected) {
          fatal("%s: Global gc-state: expected %d, actual %d", label, expected, actual);
        }
  
        VerifyThreadGCState vtgcs(label, expected);
        Threads::java_threads_do(&vtgcs);
--- 751,12 ---
          assert(false, "Unhandled gc-state verification");
      }
  
      if (enabled) {
        char actual = _heap->gc_state();
!       // Old generation marking is allowed in all states.
+       if (actual != expected && !(actual & ShenandoahHeap::OLD_MARKING)) {
          fatal("%s: Global gc-state: expected %d, actual %d", label, expected, actual);
        }
  
        VerifyThreadGCState vtgcs(label, expected);
        Threads::java_threads_do(&vtgcs);

*** 679,10 ***
--- 770,11 ---
    {
      ShenandoahHeapLocker lock(_heap->lock());
  
      ShenandoahCalculateRegionStatsClosure cl;
      _heap->heap_region_iterate(&cl);
+ 
      size_t heap_used = _heap->used();
      guarantee(cl.used() == heap_used,
                "%s: heap used size must be consistent: heap-used = " SIZE_FORMAT "%s, regions-used = " SIZE_FORMAT "%s",
                label,
                byte_size_in_proper_unit(heap_used), proper_unit_for_byte_size(heap_used),

*** 694,16 ***
                label,
                byte_size_in_proper_unit(heap_committed), proper_unit_for_byte_size(heap_committed),
                byte_size_in_proper_unit(cl.committed()), proper_unit_for_byte_size(cl.committed()));
    }
  
    // Internal heap region checks
    if (ShenandoahVerifyLevel >= 1) {
      ShenandoahVerifyHeapRegionClosure cl(label, regions);
!     _heap->heap_region_iterate(&cl);
    }
  
    OrderAccess::fence();
  
    if (UseTLAB) {
      _heap->labs_make_parsable();
    }
--- 786,67 ---
                label,
                byte_size_in_proper_unit(heap_committed), proper_unit_for_byte_size(heap_committed),
                byte_size_in_proper_unit(cl.committed()), proper_unit_for_byte_size(cl.committed()));
    }
  
+   log_debug(gc)("Safepoint verification finished heap usage verification");
+ 
+   ShenandoahGeneration* generation;
+   if (_heap->mode()->is_generational()) {
+     generation = _heap->active_generation();
+     guarantee(generation != NULL, "Need to know which generation to verify.");
+   } else {
+     generation = NULL;
+   }
+ 
+   if (generation != NULL) {
+     ShenandoahHeapLocker lock(_heap->lock());
+ 
+     if (remembered == _verify_remembered_for_marking) {
+       log_debug(gc)("Safepoint verification of remembered set at mark");
+     } else if (remembered == _verify_remembered_for_updating_references) {
+       log_debug(gc)("Safepoint verification of remembered set at update ref");
+     } else if (remembered == _verify_remembered_after_full_gc) {
+       log_debug(gc)("Safepoint verification of remembered set after full gc");
+     }
+ 
+     if (remembered == _verify_remembered_for_marking) {
+       _heap->verify_rem_set_at_mark();
+     } else if (remembered == _verify_remembered_for_updating_references) {
+       _heap->verify_rem_set_at_update_ref();
+     } else if (remembered == _verify_remembered_after_full_gc) {
+       _heap->verify_rem_set_after_full_gc();
+     }
+ 
+     ShenandoahGenerationStatsClosure cl;
+     _heap->heap_region_iterate(&cl);
+ 
+     if (LogTarget(Debug, gc)::is_enabled()) {
+       ShenandoahGenerationStatsClosure::log_usage(_heap->old_generation(), cl.old);
+       ShenandoahGenerationStatsClosure::log_usage(_heap->young_generation(), cl.young);
+       ShenandoahGenerationStatsClosure::log_usage(_heap->global_generation(), cl.global);
+     }
+ 
+     ShenandoahGenerationStatsClosure::validate_usage(label, _heap->old_generation(), cl.old);
+     ShenandoahGenerationStatsClosure::validate_usage(label, _heap->young_generation(), cl.young);
+     ShenandoahGenerationStatsClosure::validate_usage(label, _heap->global_generation(), cl.global);
+   }
+ 
+   log_debug(gc)("Safepoint verification finished remembered set verification");
+ 
    // Internal heap region checks
    if (ShenandoahVerifyLevel >= 1) {
      ShenandoahVerifyHeapRegionClosure cl(label, regions);
!     if (generation != NULL) {
+       generation->heap_region_iterate(&cl);
+     } else {
+       _heap->heap_region_iterate(&cl);
+     }
    }
  
+   log_debug(gc)("Safepoint verification finished heap region closure verification");
+ 
    OrderAccess::fence();
  
    if (UseTLAB) {
      _heap->labs_make_parsable();
    }

*** 724,10 ***
--- 867,12 ---
      ShenandoahVerifierReachableTask task(_verification_bit_map, ld, label, options);
      _heap->workers()->run_task(&task);
      count_reachable = task.processed();
    }
  
+   log_debug(gc)("Safepoint verification finished getting initial reachable set");
+ 
    // Step 3. Walk marked objects. Marked objects might be unreachable. This verifies what collector,
    // not the application, can see during the region scans. There is no reason to process the objects
    // that were already verified, e.g. those marked in verification bitmap. There is interaction with TAMS:
    // before TAMS, we verify the bitmaps, if available; after TAMS, we walk until the top(). It mimics
    // what marked_object_iterate is doing, without calling into that optimized (and possibly incorrect)

*** 741,16 ***
--- 886,21 ---
      count_marked = task.processed();
    } else {
      guarantee(ShenandoahVerifyLevel < 4 || marked == _verify_marked_incomplete || marked == _verify_marked_disable, "Should be");
    }
  
+   log_debug(gc)("Safepoint verification finished walking marked objects");
+ 
    // Step 4. Verify accumulated liveness data, if needed. Only reliable if verification level includes
    // marked objects.
  
    if (ShenandoahVerifyLevel >= 4 && marked == _verify_marked_complete && liveness == _verify_liveness_complete) {
      for (size_t i = 0; i < _heap->num_regions(); i++) {
        ShenandoahHeapRegion* r = _heap->get_region(i);
+       if (generation != NULL && !generation->contains(r)) {
+         continue;
+       }
  
        juint verf_live = 0;
        if (r->is_humongous()) {
          // For humongous objects, test if start region is marked live, and if so,
          // all humongous regions in that chain have live data equal to their "used".

*** 771,19 ***
--- 921,23 ---
                label, reg_live, verf_live, ss.as_string());
        }
      }
    }
  
+   log_debug(gc)("Safepoint verification finished accumulation of liveness data");
+ 
+ 
    log_info(gc)("Verify %s, Level " INTX_FORMAT " (" SIZE_FORMAT " reachable, " SIZE_FORMAT " marked)",
                 label, ShenandoahVerifyLevel, count_reachable, count_marked);
  
    FREE_C_HEAP_ARRAY(ShenandoahLivenessData, ld);
  }
  
  void ShenandoahVerifier::verify_generic(VerifyOption vo) {
    verify_at_safepoint(
            "Generic Verification",
+           _verify_remembered_disable,  // do not verify remembered set
            _verify_forwarded_allow,     // conservatively allow forwarded
            _verify_marked_disable,      // do not verify marked: lots ot time wasted checking dead allocations
            _verify_cset_disable,        // cset may be inconsistent
            _verify_liveness_disable,    // no reliable liveness data
            _verify_regions_disable,     // no reliable region data

*** 792,10 ***
--- 946,11 ---
  }
  
  void ShenandoahVerifier::verify_before_concmark() {
      verify_at_safepoint(
            "Before Mark",
+           _verify_remembered_for_marking,  // verify read-only remembered set from bottom() to top()
            _verify_forwarded_none,      // UR should have fixed up
            _verify_marked_disable,      // do not verify marked: lots ot time wasted checking dead allocations
            _verify_cset_none,           // UR should have fixed this
            _verify_liveness_disable,    // no reliable liveness data
            _verify_regions_notrash,     // no trash regions

*** 804,10 ***
--- 959,11 ---
  }
  
  void ShenandoahVerifier::verify_after_concmark() {
    verify_at_safepoint(
            "After Mark",
+           _verify_remembered_disable,  // do not verify remembered set
            _verify_forwarded_none,      // no forwarded references
            _verify_marked_complete_except_references, // bitmaps as precise as we can get, except dangling j.l.r.Refs
            _verify_cset_none,           // no references to cset anymore
            _verify_liveness_complete,   // liveness data must be complete here
            _verify_regions_disable,     // trash regions not yet recycled

*** 816,10 ***
--- 972,11 ---
  }
  
  void ShenandoahVerifier::verify_before_evacuation() {
    verify_at_safepoint(
            "Before Evacuation",
+           _verify_remembered_disable,                // do not verify remembered set
            _verify_forwarded_none,                    // no forwarded references
            _verify_marked_complete_except_references, // walk over marked objects too
            _verify_cset_disable,                      // non-forwarded references to cset expected
            _verify_liveness_complete,                 // liveness data must be complete here
            _verify_regions_disable,                   // trash regions not yet recycled

*** 828,10 ***
--- 985,11 ---
  }
  
  void ShenandoahVerifier::verify_during_evacuation() {
    verify_at_safepoint(
            "During Evacuation",
+           _verify_remembered_disable, // do not verify remembered set
            _verify_forwarded_allow,    // some forwarded references are allowed
            _verify_marked_disable,     // walk only roots
            _verify_cset_disable,       // some cset references are not forwarded yet
            _verify_liveness_disable,   // liveness data might be already stale after pre-evacs
            _verify_regions_disable,    // trash regions not yet recycled

*** 840,10 ***
--- 998,11 ---
  }
  
  void ShenandoahVerifier::verify_after_evacuation() {
    verify_at_safepoint(
            "After Evacuation",
+           _verify_remembered_disable,  // do not verify remembered set
            _verify_forwarded_allow,     // objects are still forwarded
            _verify_marked_complete,     // bitmaps might be stale, but alloc-after-mark should be well
            _verify_cset_forwarded,      // all cset refs are fully forwarded
            _verify_liveness_disable,    // no reliable liveness data anymore
            _verify_regions_notrash,     // trash regions have been recycled already

*** 852,22 ***
  }
  
  void ShenandoahVerifier::verify_before_updaterefs() {
    verify_at_safepoint(
            "Before Updating References",
!           _verify_forwarded_allow,     // forwarded references allowed
!           _verify_marked_complete,     // bitmaps might be stale, but alloc-after-mark should be well
!           _verify_cset_forwarded,      // all cset refs are fully forwarded
!           _verify_liveness_disable,    // no reliable liveness data anymore
!           _verify_regions_notrash,     // trash regions have been recycled already
!           _verify_gcstate_forwarded    // evacuation should have produced some forwarded objects
    );
  }
  
  void ShenandoahVerifier::verify_after_updaterefs() {
    verify_at_safepoint(
            "After Updating References",
            _verify_forwarded_none,      // no forwarded references
            _verify_marked_complete,     // bitmaps might be stale, but alloc-after-mark should be well
            _verify_cset_none,           // no cset references, all updated
            _verify_liveness_disable,    // no reliable liveness data anymore
            _verify_regions_nocset,      // no cset regions, trash regions have appeared
--- 1011,24 ---
  }
  
  void ShenandoahVerifier::verify_before_updaterefs() {
    verify_at_safepoint(
            "Before Updating References",
!           _verify_remembered_for_updating_references,  // verify read-write remembered set
!           _verify_forwarded_allow,                     // forwarded references allowed
!           _verify_marked_complete,                     // bitmaps might be stale, but alloc-after-mark should be well
!           _verify_cset_forwarded,                      // all cset refs are fully forwarded
!           _verify_liveness_disable,                    // no reliable liveness data anymore
!           _verify_regions_notrash,                     // trash regions have been recycled already
+           _verify_gcstate_updating                     // evacuation should have produced some forwarded objects
    );
  }
  
  void ShenandoahVerifier::verify_after_updaterefs() {
    verify_at_safepoint(
            "After Updating References",
+           _verify_remembered_disable,  // do not verify remembered set
            _verify_forwarded_none,      // no forwarded references
            _verify_marked_complete,     // bitmaps might be stale, but alloc-after-mark should be well
            _verify_cset_none,           // no cset references, all updated
            _verify_liveness_disable,    // no reliable liveness data anymore
            _verify_regions_nocset,      // no cset regions, trash regions have appeared

*** 876,10 ***
--- 1037,11 ---
  }
  
  void ShenandoahVerifier::verify_after_degenerated() {
    verify_at_safepoint(
            "After Degenerated GC",
+           _verify_remembered_disable,  // do not verify remembered set
            _verify_forwarded_none,      // all objects are non-forwarded
            _verify_marked_complete,     // all objects are marked in complete bitmap
            _verify_cset_none,           // no cset references
            _verify_liveness_disable,    // no reliable liveness data anymore
            _verify_regions_notrash_nocset, // no trash, no cset

*** 888,32 ***
  }
  
  void ShenandoahVerifier::verify_before_fullgc() {
    verify_at_safepoint(
            "Before Full GC",
            _verify_forwarded_allow,     // can have forwarded objects
            _verify_marked_disable,      // do not verify marked: lots ot time wasted checking dead allocations
            _verify_cset_disable,        // cset might be foobared
            _verify_liveness_disable,    // no reliable liveness data anymore
            _verify_regions_disable,     // no reliable region data here
            _verify_gcstate_disable      // no reliable gcstate data
    );
  }
  
  void ShenandoahVerifier::verify_after_fullgc() {
    verify_at_safepoint(
            "After Full GC",
            _verify_forwarded_none,      // all objects are non-forwarded
            _verify_marked_complete,     // all objects are marked in complete bitmap
            _verify_cset_none,           // no cset references
            _verify_liveness_disable,    // no reliable liveness data anymore
            _verify_regions_notrash_nocset, // no trash, no cset
            _verify_gcstate_stable        // full gc cleaned up everything
    );
  }
  
! class ShenandoahVerifyNoForwared : public OopClosure {
  private:
    template <class T>
    void do_oop_work(T* p) {
      T o = RawAccess<>::oop_load(p);
      if (!CompressedOops::is_null(o)) {
--- 1050,47 ---
  }
  
  void ShenandoahVerifier::verify_before_fullgc() {
    verify_at_safepoint(
            "Before Full GC",
+           _verify_remembered_disable,  // do not verify remembered set
            _verify_forwarded_allow,     // can have forwarded objects
            _verify_marked_disable,      // do not verify marked: lots ot time wasted checking dead allocations
            _verify_cset_disable,        // cset might be foobared
            _verify_liveness_disable,    // no reliable liveness data anymore
            _verify_regions_disable,     // no reliable region data here
            _verify_gcstate_disable      // no reliable gcstate data
    );
  }
  
+ void ShenandoahVerifier::verify_after_generational_fullgc() {
+   verify_at_safepoint(
+           "After Full Generational GC",
+           _verify_remembered_after_full_gc,  // verify read-write remembered set
+           _verify_forwarded_none,      // all objects are non-forwarded
+           _verify_marked_complete,     // all objects are marked in complete bitmap
+           _verify_cset_none,           // no cset references
+           _verify_liveness_disable,    // no reliable liveness data anymore
+           _verify_regions_notrash_nocset, // no trash, no cset
+           _verify_gcstate_stable       // full gc cleaned up everything
+   );
+ }
+ 
  void ShenandoahVerifier::verify_after_fullgc() {
    verify_at_safepoint(
            "After Full GC",
+           _verify_remembered_disable,  // do not verify remembered set
            _verify_forwarded_none,      // all objects are non-forwarded
            _verify_marked_complete,     // all objects are marked in complete bitmap
            _verify_cset_none,           // no cset references
            _verify_liveness_disable,    // no reliable liveness data anymore
            _verify_regions_notrash_nocset, // no trash, no cset
            _verify_gcstate_stable        // full gc cleaned up everything
    );
  }
  
! class ShenandoahVerifyNoForwared : public BasicOopIterateClosure {
  private:
    template <class T>
    void do_oop_work(T* p) {
      T o = RawAccess<>::oop_load(p);
      if (!CompressedOops::is_null(o)) {

*** 929,20 ***
  public:
    void do_oop(narrowOop* p) { do_oop_work(p); }
    void do_oop(oop* p)       { do_oop_work(p); }
  };
  
! class ShenandoahVerifyInToSpaceClosure : public OopClosure {
  private:
    template <class T>
    void do_oop_work(T* p) {
      T o = RawAccess<>::oop_load(p);
      if (!CompressedOops::is_null(o)) {
        oop obj = CompressedOops::decode_not_null(o);
        ShenandoahHeap* heap = ShenandoahHeap::heap();
  
!       if (!heap->marking_context()->is_marked(obj)) {
          ShenandoahAsserts::print_failure(ShenandoahAsserts::_safe_all, obj, p, NULL,
                  "Verify Roots In To-Space", "Should be marked", __FILE__, __LINE__);
        }
  
        if (heap->in_collection_set(obj)) {
--- 1106,20 ---
  public:
    void do_oop(narrowOop* p) { do_oop_work(p); }
    void do_oop(oop* p)       { do_oop_work(p); }
  };
  
! class ShenandoahVerifyInToSpaceClosure : public BasicOopIterateClosure {
  private:
    template <class T>
    void do_oop_work(T* p) {
      T o = RawAccess<>::oop_load(p);
      if (!CompressedOops::is_null(o)) {
        oop obj = CompressedOops::decode_not_null(o);
        ShenandoahHeap* heap = ShenandoahHeap::heap();
  
!       if (!heap->marking_context()->is_marked_or_old(obj)) {
          ShenandoahAsserts::print_failure(ShenandoahAsserts::_safe_all, obj, p, NULL,
                  "Verify Roots In To-Space", "Should be marked", __FILE__, __LINE__);
        }
  
        if (heap->in_collection_set(obj)) {
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