--- a/hotspot/src/share/vm/gc_implementation/g1/concurrentMark.cpp	Tue Jun 14 10:33:43 2011 -0400
+++ b/hotspot/src/share/vm/gc_implementation/g1/concurrentMark.cpp	Tue Jun 14 11:01:10 2011 -0700
@@ -782,7 +782,7 @@
 #ifndef PRODUCT
   if (G1PrintReachableAtInitialMark) {
     print_reachable("at-cycle-start",
-                    true /* use_prev_marking */, true /* all */);
+                    VerifyOption_G1UsePrevMarking, true /* all */);
   }
 #endif
 
@@ -1200,7 +1200,9 @@
     HandleMark hm;  // handle scope
     gclog_or_tty->print(" VerifyDuringGC:(before)");
     Universe::heap()->prepare_for_verify();
-    Universe::verify(true, false, true);
+    Universe::verify(/* allow dirty */ true,
+                     /* silent      */ false,
+                     /* option      */ VerifyOption_G1UsePrevMarking);
   }
 
   G1CollectorPolicy* g1p = g1h->g1_policy();
@@ -1233,9 +1235,9 @@
       HandleMark hm;  // handle scope
       gclog_or_tty->print(" VerifyDuringGC:(after)");
       Universe::heap()->prepare_for_verify();
-      Universe::heap()->verify(/* allow_dirty */      true,
-                               /* silent */           false,
-                               /* use_prev_marking */ false);
+      Universe::verify(/* allow dirty */ true,
+                       /* silent      */ false,
+                       /* option      */ VerifyOption_G1UseNextMarking);
     }
     assert(!restart_for_overflow(), "sanity");
   }
@@ -1725,9 +1727,9 @@
     HandleMark hm;  // handle scope
     gclog_or_tty->print(" VerifyDuringGC:(before)");
     Universe::heap()->prepare_for_verify();
-    Universe::verify(/* allow dirty  */ true,
-                     /* silent       */ false,
-                     /* prev marking */ true);
+    Universe::verify(/* allow dirty */ true,
+                     /* silent      */ false,
+                     /* option      */ VerifyOption_G1UsePrevMarking);
   }
 
   G1CollectorPolicy* g1p = G1CollectedHeap::heap()->g1_policy();
@@ -1873,9 +1875,9 @@
     HandleMark hm;  // handle scope
     gclog_or_tty->print(" VerifyDuringGC:(after)");
     Universe::heap()->prepare_for_verify();
-    Universe::verify(/* allow dirty  */ true,
-                     /* silent       */ false,
-                     /* prev marking */ true);
+    Universe::verify(/* allow dirty */ true,
+                     /* silent      */ false,
+                     /* option      */ VerifyOption_G1UsePrevMarking);
   }
 
   g1h->verify_region_sets_optional();
@@ -2344,18 +2346,16 @@
 class PrintReachableOopClosure: public OopClosure {
 private:
   G1CollectedHeap* _g1h;
-  CMBitMapRO*      _bitmap;
   outputStream*    _out;
-  bool             _use_prev_marking;
+  VerifyOption     _vo;
   bool             _all;
 
 public:
-  PrintReachableOopClosure(CMBitMapRO*   bitmap,
-                           outputStream* out,
-                           bool          use_prev_marking,
+  PrintReachableOopClosure(outputStream* out,
+                           VerifyOption  vo,
                            bool          all) :
     _g1h(G1CollectedHeap::heap()),
-    _bitmap(bitmap), _out(out), _use_prev_marking(use_prev_marking), _all(all) { }
+    _out(out), _vo(vo), _all(all) { }
 
   void do_oop(narrowOop* p) { do_oop_work(p); }
   void do_oop(      oop* p) { do_oop_work(p); }
@@ -2373,12 +2373,23 @@
       HeapRegion* hr  = _g1h->heap_region_containing(obj);
       guarantee(hr != NULL, "invariant");
       bool over_tams = false;
-      if (_use_prev_marking) {
-        over_tams = hr->obj_allocated_since_prev_marking(obj);
-      } else {
-        over_tams = hr->obj_allocated_since_next_marking(obj);
+      bool marked = false;
+
+      switch (_vo) {
+        case VerifyOption_G1UsePrevMarking:
+          over_tams = hr->obj_allocated_since_prev_marking(obj);
+          marked = _g1h->isMarkedPrev(obj);
+          break;
+        case VerifyOption_G1UseNextMarking:
+          over_tams = hr->obj_allocated_since_next_marking(obj);
+          marked = _g1h->isMarkedNext(obj);
+          break;
+        case VerifyOption_G1UseMarkWord:
+          marked = obj->is_gc_marked();
+          break;
+        default:
+          ShouldNotReachHere();
       }
-      bool marked = _bitmap->isMarked((HeapWord*) obj);
 
       if (over_tams) {
         str = " >";
@@ -2399,35 +2410,45 @@
 
 class PrintReachableObjectClosure : public ObjectClosure {
 private:
-  CMBitMapRO*   _bitmap;
-  outputStream* _out;
-  bool          _use_prev_marking;
-  bool          _all;
-  HeapRegion*   _hr;
+  G1CollectedHeap* _g1h;
+  outputStream*    _out;
+  VerifyOption     _vo;
+  bool             _all;
+  HeapRegion*      _hr;
 
 public:
-  PrintReachableObjectClosure(CMBitMapRO*   bitmap,
-                              outputStream* out,
-                              bool          use_prev_marking,
+  PrintReachableObjectClosure(outputStream* out,
+                              VerifyOption  vo,
                               bool          all,
                               HeapRegion*   hr) :
-    _bitmap(bitmap), _out(out),
-    _use_prev_marking(use_prev_marking), _all(all), _hr(hr) { }
+    _g1h(G1CollectedHeap::heap()),
+    _out(out), _vo(vo), _all(all), _hr(hr) { }
 
   void do_object(oop o) {
-    bool over_tams;
-    if (_use_prev_marking) {
-      over_tams = _hr->obj_allocated_since_prev_marking(o);
-    } else {
-      over_tams = _hr->obj_allocated_since_next_marking(o);
+    bool over_tams = false;
+    bool marked = false;
+
+    switch (_vo) {
+      case VerifyOption_G1UsePrevMarking:
+        over_tams = _hr->obj_allocated_since_prev_marking(o);
+        marked = _g1h->isMarkedPrev(o);
+        break;
+      case VerifyOption_G1UseNextMarking:
+        over_tams = _hr->obj_allocated_since_next_marking(o);
+        marked = _g1h->isMarkedNext(o);
+        break;
+      case VerifyOption_G1UseMarkWord:
+        marked = o->is_gc_marked();
+        break;
+      default:
+        ShouldNotReachHere();
     }
-    bool marked = _bitmap->isMarked((HeapWord*) o);
     bool print_it = _all || over_tams || marked;
 
     if (print_it) {
       _out->print_cr(" "PTR_FORMAT"%s",
                      o, (over_tams) ? " >" : (marked) ? " M" : "");
-      PrintReachableOopClosure oopCl(_bitmap, _out, _use_prev_marking, _all);
+      PrintReachableOopClosure oopCl(_out, _vo, _all);
       o->oop_iterate(&oopCl);
     }
   }
@@ -2435,9 +2456,8 @@
 
 class PrintReachableRegionClosure : public HeapRegionClosure {
 private:
-  CMBitMapRO*   _bitmap;
   outputStream* _out;
-  bool          _use_prev_marking;
+  VerifyOption  _vo;
   bool          _all;
 
 public:
@@ -2446,10 +2466,21 @@
     HeapWord* e = hr->end();
     HeapWord* t = hr->top();
     HeapWord* p = NULL;
-    if (_use_prev_marking) {
-      p = hr->prev_top_at_mark_start();
-    } else {
-      p = hr->next_top_at_mark_start();
+
+    switch (_vo) {
+      case VerifyOption_G1UsePrevMarking:
+        p = hr->prev_top_at_mark_start();
+        break;
+      case VerifyOption_G1UseNextMarking:
+        p = hr->next_top_at_mark_start();
+        break;
+      case VerifyOption_G1UseMarkWord:
+        // When we are verifying marking using the mark word
+        // TAMS has no relevance.
+        assert(p == NULL, "post-condition");
+        break;
+      default:
+        ShouldNotReachHere();
     }
     _out->print_cr("** ["PTR_FORMAT", "PTR_FORMAT"] top: "PTR_FORMAT" "
                    "TAMS: "PTR_FORMAT, b, e, t, p);
@@ -2461,8 +2492,7 @@
     if (to > from) {
       _out->print_cr("Objects in ["PTR_FORMAT", "PTR_FORMAT"]", from, to);
       _out->cr();
-      PrintReachableObjectClosure ocl(_bitmap, _out,
-                                      _use_prev_marking, _all, hr);
+      PrintReachableObjectClosure ocl(_out, _vo, _all, hr);
       hr->object_iterate_mem_careful(MemRegion(from, to), &ocl);
       _out->cr();
     }
@@ -2470,15 +2500,25 @@
     return false;
   }
 
-  PrintReachableRegionClosure(CMBitMapRO*   bitmap,
-                              outputStream* out,
-                              bool          use_prev_marking,
+  PrintReachableRegionClosure(outputStream* out,
+                              VerifyOption  vo,
                               bool          all) :
-    _bitmap(bitmap), _out(out), _use_prev_marking(use_prev_marking), _all(all) { }
+    _out(out), _vo(vo), _all(all) { }
 };
 
+static const char* verify_option_to_tams(VerifyOption vo) {
+  switch (vo) {
+    case VerifyOption_G1UsePrevMarking:
+      return "PTAMS";
+    case VerifyOption_G1UseNextMarking:
+      return "NTAMS";
+    default:
+      return "NONE";
+  }
+}
+
 void ConcurrentMark::print_reachable(const char* str,
-                                     bool use_prev_marking,
+                                     VerifyOption vo,
                                      bool all) {
   gclog_or_tty->cr();
   gclog_or_tty->print_cr("== Doing heap dump... ");
@@ -2505,20 +2545,12 @@
   }
 
   outputStream* out = &fout;
-
-  CMBitMapRO* bitmap = NULL;
-  if (use_prev_marking) {
-    bitmap = _prevMarkBitMap;
-  } else {
-    bitmap = _nextMarkBitMap;
-  }
-
-  out->print_cr("-- USING %s", (use_prev_marking) ? "PTAMS" : "NTAMS");
+  out->print_cr("-- USING %s", verify_option_to_tams(vo));
   out->cr();
 
   out->print_cr("--- ITERATING OVER REGIONS");
   out->cr();
-  PrintReachableRegionClosure rcl(bitmap, out, use_prev_marking, all);
+  PrintReachableRegionClosure rcl(out, vo, all);
   _g1h->heap_region_iterate(&rcl);
   out->cr();
 

--- a/hotspot/src/share/vm/gc_implementation/g1/concurrentMark.hpp	Tue Jun 14 10:33:43 2011 -0400
+++ b/hotspot/src/share/vm/gc_implementation/g1/concurrentMark.hpp	Tue Jun 14 11:01:10 2011 -0700
@@ -736,12 +736,14 @@
   // will dump the contents of its reference fields, as well as
   // liveness information for the object and its referents. The dump
   // will be written to a file with the following name:
-  // G1PrintReachableBaseFile + "." + str. use_prev_marking decides
-  // whether the prev (use_prev_marking == true) or next
-  // (use_prev_marking == false) marking information will be used to
-  // determine the liveness of each object / referent. If all is true,
-  // all objects in the heap will be dumped, otherwise only the live
-  // ones. In the dump the following symbols / abbreviations are used:
+  // G1PrintReachableBaseFile + "." + str.
+  // vo decides whether the prev (vo == UsePrevMarking), the next
+  // (vo == UseNextMarking) marking information, or the mark word
+  // (vo == UseMarkWord) will be used to determine the liveness of
+  // each object / referent.
+  // If all is true, all objects in the heap will be dumped, otherwise
+  // only the live ones. In the dump the following symbols / breviations
+  // are used:
   //   M : an explicitly live object (its bitmap bit is set)
   //   > : an implicitly live object (over tams)
   //   O : an object outside the G1 heap (typically: in the perm gen)
@@ -749,7 +751,7 @@
   //   AND MARKED : indicates that an object is both explicitly and
   //   implicitly live (it should be one or the other, not both)
   void print_reachable(const char* str,
-                       bool use_prev_marking, bool all) PRODUCT_RETURN;
+                       VerifyOption vo, bool all) PRODUCT_RETURN;
 
   // Clear the next marking bitmap (will be called concurrently).
   void clearNextBitmap();

--- a/hotspot/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp	Tue Jun 14 10:33:43 2011 -0400
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp	Tue Jun 14 11:01:10 2011 -0700
@@ -1211,7 +1211,10 @@
       HandleMark hm;  // Discard invalid handles created during verification
       gclog_or_tty->print(" VerifyBeforeGC:");
       prepare_for_verify();
-      Universe::verify(true);
+      Universe::verify(/* allow dirty */ true,
+                       /* silent      */ false,
+                       /* option      */ VerifyOption_G1UsePrevMarking);
+
     }
 
     COMPILER2_PRESENT(DerivedPointerTable::clear());
@@ -1263,7 +1266,6 @@
 
     ref_processor()->enable_discovery();
     ref_processor()->setup_policy(do_clear_all_soft_refs);
-
     // Do collection work
     {
       HandleMark hm;  // Discard invalid handles created during gc
@@ -1284,7 +1286,10 @@
       HandleMark hm;  // Discard invalid handles created during verification
       gclog_or_tty->print(" VerifyAfterGC:");
       prepare_for_verify();
-      Universe::verify(false);
+      Universe::verify(/* allow dirty */ false,
+                       /* silent      */ false,
+                       /* option      */ VerifyOption_G1UsePrevMarking);
+
     }
     NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
 
@@ -2639,17 +2644,18 @@
 }
 
 class VerifyLivenessOopClosure: public OopClosure {
-  G1CollectedHeap* g1h;
+  G1CollectedHeap* _g1h;
+  VerifyOption _vo;
 public:
-  VerifyLivenessOopClosure(G1CollectedHeap* _g1h) {
-    g1h = _g1h;
-  }
+  VerifyLivenessOopClosure(G1CollectedHeap* g1h, VerifyOption vo):
+    _g1h(g1h), _vo(vo)
+  { }
   void do_oop(narrowOop *p) { do_oop_work(p); }
   void do_oop(      oop *p) { do_oop_work(p); }
 
   template <class T> void do_oop_work(T *p) {
     oop obj = oopDesc::load_decode_heap_oop(p);
-    guarantee(obj == NULL || !g1h->is_obj_dead(obj),
+    guarantee(obj == NULL || !_g1h->is_obj_dead_cond(obj, _vo),
               "Dead object referenced by a not dead object");
   }
 };
@@ -2659,18 +2665,30 @@
   G1CollectedHeap* _g1h;
   size_t _live_bytes;
   HeapRegion *_hr;
-  bool _use_prev_marking;
+  VerifyOption _vo;
 public:
-  // use_prev_marking == true  -> use "prev" marking information,
-  // use_prev_marking == false -> use "next" marking information
-  VerifyObjsInRegionClosure(HeapRegion *hr, bool use_prev_marking)
-    : _live_bytes(0), _hr(hr), _use_prev_marking(use_prev_marking) {
+  // _vo == UsePrevMarking -> use "prev" marking information,
+  // _vo == UseNextMarking -> use "next" marking information,
+  // _vo == UseMarkWord    -> use mark word from object header.
+  VerifyObjsInRegionClosure(HeapRegion *hr, VerifyOption vo)
+    : _live_bytes(0), _hr(hr), _vo(vo) {
     _g1h = G1CollectedHeap::heap();
   }
   void do_object(oop o) {
-    VerifyLivenessOopClosure isLive(_g1h);
+    VerifyLivenessOopClosure isLive(_g1h, _vo);
     assert(o != NULL, "Huh?");
-    if (!_g1h->is_obj_dead_cond(o, _use_prev_marking)) {
+    if (!_g1h->is_obj_dead_cond(o, _vo)) {
+      // If the object is alive according to the mark word,
+      // then verify that the marking information agrees.
+      // Note we can't verify the contra-positive of the
+      // above: if the object is dead (according to the mark
+      // word), it may not be marked, or may have been marked
+      // but has since became dead, or may have been allocated
+      // since the last marking.
+      if (_vo == VerifyOption_G1UseMarkWord) {
+        guarantee(!_g1h->is_obj_dead(o), "mark word and concurrent mark mismatch");
+      }
+
       o->oop_iterate(&isLive);
       if (!_hr->obj_allocated_since_prev_marking(o)) {
         size_t obj_size = o->size();    // Make sure we don't overflow
@@ -2712,17 +2730,18 @@
 
 class VerifyRegionClosure: public HeapRegionClosure {
 private:
-  bool _allow_dirty;
-  bool _par;
-  bool _use_prev_marking;
-  bool _failures;
+  bool         _allow_dirty;
+  bool         _par;
+  VerifyOption _vo;
+  bool         _failures;
 public:
-  // use_prev_marking == true  -> use "prev" marking information,
-  // use_prev_marking == false -> use "next" marking information
-  VerifyRegionClosure(bool allow_dirty, bool par, bool use_prev_marking)
+  // _vo == UsePrevMarking -> use "prev" marking information,
+  // _vo == UseNextMarking -> use "next" marking information,
+  // _vo == UseMarkWord    -> use mark word from object header.
+  VerifyRegionClosure(bool allow_dirty, bool par, VerifyOption vo)
     : _allow_dirty(allow_dirty),
       _par(par),
-      _use_prev_marking(use_prev_marking),
+      _vo(vo),
       _failures(false) {}
 
   bool failures() {
@@ -2734,11 +2753,11 @@
               "Should be unclaimed at verify points.");
     if (!r->continuesHumongous()) {
       bool failures = false;
-      r->verify(_allow_dirty, _use_prev_marking, &failures);
+      r->verify(_allow_dirty, _vo, &failures);
       if (failures) {
         _failures = true;
       } else {
-        VerifyObjsInRegionClosure not_dead_yet_cl(r, _use_prev_marking);
+        VerifyObjsInRegionClosure not_dead_yet_cl(r, _vo);
         r->object_iterate(&not_dead_yet_cl);
         if (r->max_live_bytes() < not_dead_yet_cl.live_bytes()) {
           gclog_or_tty->print_cr("["PTR_FORMAT","PTR_FORMAT"] "
@@ -2758,14 +2777,15 @@
 class VerifyRootsClosure: public OopsInGenClosure {
 private:
   G1CollectedHeap* _g1h;
-  bool             _use_prev_marking;
+  VerifyOption     _vo;
   bool             _failures;
 public:
-  // use_prev_marking == true  -> use "prev" marking information,
-  // use_prev_marking == false -> use "next" marking information
-  VerifyRootsClosure(bool use_prev_marking) :
+  // _vo == UsePrevMarking -> use "prev" marking information,
+  // _vo == UseNextMarking -> use "next" marking information,
+  // _vo == UseMarkWord    -> use mark word from object header.
+  VerifyRootsClosure(VerifyOption vo) :
     _g1h(G1CollectedHeap::heap()),
-    _use_prev_marking(use_prev_marking),
+    _vo(vo),
     _failures(false) { }
 
   bool failures() { return _failures; }
@@ -2774,9 +2794,12 @@
     T heap_oop = oopDesc::load_heap_oop(p);
     if (!oopDesc::is_null(heap_oop)) {
       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
-      if (_g1h->is_obj_dead_cond(obj, _use_prev_marking)) {
+      if (_g1h->is_obj_dead_cond(obj, _vo)) {
         gclog_or_tty->print_cr("Root location "PTR_FORMAT" "
                               "points to dead obj "PTR_FORMAT, p, (void*) obj);
+        if (_vo == VerifyOption_G1UseMarkWord) {
+          gclog_or_tty->print_cr("  Mark word: "PTR_FORMAT, (void*)(obj->mark()));
+        }
         obj->print_on(gclog_or_tty);
         _failures = true;
       }
@@ -2792,19 +2815,19 @@
 class G1ParVerifyTask: public AbstractGangTask {
 private:
   G1CollectedHeap* _g1h;
-  bool _allow_dirty;
-  bool _use_prev_marking;
-  bool _failures;
+  bool             _allow_dirty;
+  VerifyOption     _vo;
+  bool             _failures;
 
 public:
-  // use_prev_marking == true  -> use "prev" marking information,
-  // use_prev_marking == false -> use "next" marking information
-  G1ParVerifyTask(G1CollectedHeap* g1h, bool allow_dirty,
-                  bool use_prev_marking) :
+  // _vo == UsePrevMarking -> use "prev" marking information,
+  // _vo == UseNextMarking -> use "next" marking information,
+  // _vo == UseMarkWord    -> use mark word from object header.
+  G1ParVerifyTask(G1CollectedHeap* g1h, bool allow_dirty, VerifyOption vo) :
     AbstractGangTask("Parallel verify task"),
     _g1h(g1h),
     _allow_dirty(allow_dirty),
-    _use_prev_marking(use_prev_marking),
+    _vo(vo),
     _failures(false) { }
 
   bool failures() {
@@ -2813,7 +2836,7 @@
 
   void work(int worker_i) {
     HandleMark hm;
-    VerifyRegionClosure blk(_allow_dirty, true, _use_prev_marking);
+    VerifyRegionClosure blk(_allow_dirty, true, _vo);
     _g1h->heap_region_par_iterate_chunked(&blk, worker_i,
                                           HeapRegion::ParVerifyClaimValue);
     if (blk.failures()) {
@@ -2823,19 +2846,21 @@
 };
 
 void G1CollectedHeap::verify(bool allow_dirty, bool silent) {
-  verify(allow_dirty, silent, /* use_prev_marking */ true);
+  verify(allow_dirty, silent, VerifyOption_G1UsePrevMarking);
 }
 
 void G1CollectedHeap::verify(bool allow_dirty,
                              bool silent,
-                             bool use_prev_marking) {
+                             VerifyOption vo) {
   if (SafepointSynchronize::is_at_safepoint() || ! UseTLAB) {
     if (!silent) { gclog_or_tty->print("Roots (excluding permgen) "); }
-    VerifyRootsClosure rootsCl(use_prev_marking);
+    VerifyRootsClosure rootsCl(vo);
     CodeBlobToOopClosure blobsCl(&rootsCl, /*do_marking=*/ false);
+
     // We apply the relevant closures to all the oops in the
     // system dictionary, the string table and the code cache.
     const int so = SharedHeap::SO_AllClasses | SharedHeap::SO_Strings | SharedHeap::SO_CodeCache;
+
     process_strong_roots(true,      // activate StrongRootsScope
                          true,      // we set "collecting perm gen" to true,
                                     // so we don't reset the dirty cards in the perm gen.
@@ -2843,21 +2868,37 @@
                          &rootsCl,
                          &blobsCl,
                          &rootsCl);
-    // Since we used "collecting_perm_gen" == true above, we will not have
-    // checked the refs from perm into the G1-collected heap. We check those
-    // references explicitly below. Whether the relevant cards are dirty
-    // is checked further below in the rem set verification.
-    if (!silent) { gclog_or_tty->print("Permgen roots "); }
-    perm_gen()->oop_iterate(&rootsCl);
+
+    // If we're verifying after the marking phase of a Full GC then we can't
+    // treat the perm gen as roots into the G1 heap. Some of the objects in
+    // the perm gen may be dead and hence not marked. If one of these dead
+    // objects is considered to be a root then we may end up with a false
+    // "Root location <x> points to dead ob <y>" failure.
+    if (vo != VerifyOption_G1UseMarkWord) {
+      // Since we used "collecting_perm_gen" == true above, we will not have
+      // checked the refs from perm into the G1-collected heap. We check those
+      // references explicitly below. Whether the relevant cards are dirty
+      // is checked further below in the rem set verification.
+      if (!silent) { gclog_or_tty->print("Permgen roots "); }
+      perm_gen()->oop_iterate(&rootsCl);
+    }
     bool failures = rootsCl.failures();
-    if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
-    verify_region_sets();
+
+    if (vo != VerifyOption_G1UseMarkWord) {
+      // If we're verifying during a full GC then the region sets
+      // will have been torn down at the start of the GC. Therefore
+      // verifying the region sets will fail. So we only verify
+      // the region sets when not in a full GC.
+      if (!silent) { gclog_or_tty->print("HeapRegionSets "); }
+      verify_region_sets();
+    }
+
     if (!silent) { gclog_or_tty->print("HeapRegions "); }
     if (GCParallelVerificationEnabled && ParallelGCThreads > 1) {
       assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
              "sanity check");
 
-      G1ParVerifyTask task(this, allow_dirty, use_prev_marking);
+      G1ParVerifyTask task(this, allow_dirty, vo);
       int n_workers = workers()->total_workers();
       set_par_threads(n_workers);
       workers()->run_task(&task);
@@ -2874,7 +2915,7 @@
       assert(check_heap_region_claim_values(HeapRegion::InitialClaimValue),
              "sanity check");
     } else {
-      VerifyRegionClosure blk(allow_dirty, false, use_prev_marking);
+      VerifyRegionClosure blk(allow_dirty, false, vo);
       heap_region_iterate(&blk);
       if (blk.failures()) {
         failures = true;
@@ -2890,7 +2931,7 @@
 #ifndef PRODUCT
       if (VerifyDuringGC && G1VerifyDuringGCPrintReachable) {
         concurrent_mark()->print_reachable("at-verification-failure",
-                                           use_prev_marking, false /* all */);
+                                           vo, false /* all */);
       }
 #endif
       gclog_or_tty->flush();
@@ -3038,24 +3079,6 @@
   }
 }
 
-class VerifyMarkedObjsClosure: public ObjectClosure {
-    G1CollectedHeap* _g1h;
-    public:
-    VerifyMarkedObjsClosure(G1CollectedHeap* g1h) : _g1h(g1h) {}
-    void do_object(oop obj) {
-      assert(obj->mark()->is_marked() ? !_g1h->is_obj_dead(obj) : true,
-             "markandsweep mark should agree with concurrent deadness");
-    }
-};
-
-void
-G1CollectedHeap::checkConcurrentMark() {
-    VerifyMarkedObjsClosure verifycl(this);
-    //    MutexLockerEx x(getMarkBitMapLock(),
-    //              Mutex::_no_safepoint_check_flag);
-    object_iterate(&verifycl, false);
-}
-
 void G1CollectedHeap::do_sync_mark() {
   _cm->checkpointRootsInitial();
   _cm->markFromRoots();
@@ -3252,7 +3275,10 @@
         HandleMark hm;  // Discard invalid handles created during verification
         gclog_or_tty->print(" VerifyBeforeGC:");
         prepare_for_verify();
-        Universe::verify(false);
+        Universe::verify(/* allow dirty */ false,
+                         /* silent      */ false,
+                         /* option      */ VerifyOption_G1UsePrevMarking);
+
       }
 
       COMPILER2_PRESENT(DerivedPointerTable::clear());
@@ -3424,7 +3450,9 @@
         HandleMark hm;  // Discard invalid handles created during verification
         gclog_or_tty->print(" VerifyAfterGC:");
         prepare_for_verify();
-        Universe::verify(false);
+        Universe::verify(/* allow dirty */ true,
+                         /* silent      */ false,
+                         /* option      */ VerifyOption_G1UsePrevMarking);
       }
 
       if (was_enabled) ref_processor()->enable_discovery();

--- a/hotspot/src/share/vm/gc_implementation/g1/g1CollectedHeap.hpp	Tue Jun 14 10:33:43 2011 -0400
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1CollectedHeap.hpp	Tue Jun 14 11:01:10 2011 -0700
@@ -1347,14 +1347,20 @@
 
   // Perform verification.
 
-  // use_prev_marking == true  -> use "prev" marking information,
-  // use_prev_marking == false -> use "next" marking information
+  // vo == UsePrevMarking  -> use "prev" marking information,
+  // vo == UseNextMarking -> use "next" marking information
+  // vo == UseMarkWord    -> use the mark word in the object header
+  //
   // NOTE: Only the "prev" marking information is guaranteed to be
   // consistent most of the time, so most calls to this should use
-  // use_prev_marking == true. Currently, there is only one case where
-  // this is called with use_prev_marking == false, which is to verify
-  // the "next" marking information at the end of remark.
-  void verify(bool allow_dirty, bool silent, bool use_prev_marking);
+  // vo == UsePrevMarking.
+  // Currently, there is only one case where this is called with
+  // vo == UseNextMarking, which is to verify the "next" marking
+  // information at the end of remark.
+  // Currently there is only one place where this is called with
+  // vo == UseMarkWord, which is to verify the marking during a
+  // full GC.
+  void verify(bool allow_dirty, bool silent, VerifyOption vo);
 
   // Override; it uses the "prev" marking information
   virtual void verify(bool allow_dirty, bool silent);
@@ -1402,24 +1408,27 @@
   // bitmap off to the side.
   void doConcurrentMark();
 
-  // This is called from the marksweep collector which then does
-  // a concurrent mark and verifies that the results agree with
-  // the stop the world marking.
-  void checkConcurrentMark();
+  // Do a full concurrent marking, synchronously.
   void do_sync_mark();
 
   bool isMarkedPrev(oop obj) const;
   bool isMarkedNext(oop obj) const;
 
-  // use_prev_marking == true  -> use "prev" marking information,
-  // use_prev_marking == false -> use "next" marking information
+  // vo == UsePrevMarking -> use "prev" marking information,
+  // vo == UseNextMarking -> use "next" marking information,
+  // vo == UseMarkWord    -> use mark word from object header
   bool is_obj_dead_cond(const oop obj,
                         const HeapRegion* hr,
-                        const bool use_prev_marking) const {
-    if (use_prev_marking) {
-      return is_obj_dead(obj, hr);
-    } else {
-      return is_obj_ill(obj, hr);
+                        const VerifyOption vo) const {
+
+    switch (vo) {
+      case VerifyOption_G1UsePrevMarking:
+        return is_obj_dead(obj, hr);
+      case VerifyOption_G1UseNextMarking:
+        return is_obj_ill(obj, hr);
+      default:
+        assert(vo == VerifyOption_G1UseMarkWord, "must be");
+        return !obj->is_gc_marked();
     }
   }
 
@@ -1460,18 +1469,24 @@
   // Added if it is in permanent gen it isn't dead.
   // Added if it is NULL it isn't dead.
 
-  // use_prev_marking == true  -> use "prev" marking information,
-  // use_prev_marking == false -> use "next" marking information
+  // vo == UsePrevMarking -> use "prev" marking information,
+  // vo == UseNextMarking -> use "next" marking information,
+  // vo == UseMarkWord    -> use mark word from object header
   bool is_obj_dead_cond(const oop obj,
-                        const bool use_prev_marking) {
-    if (use_prev_marking) {
-      return is_obj_dead(obj);
-    } else {
-      return is_obj_ill(obj);
+                        const VerifyOption vo) const {
+
+    switch (vo) {
+      case VerifyOption_G1UsePrevMarking:
+        return is_obj_dead(obj);
+      case VerifyOption_G1UseNextMarking:
+        return is_obj_ill(obj);
+      default:
+        assert(vo == VerifyOption_G1UseMarkWord, "must be");
+        return !obj->is_gc_marked();
     }
   }
 
-  bool is_obj_dead(const oop obj) {
+  bool is_obj_dead(const oop obj) const {
     const HeapRegion* hr = heap_region_containing(obj);
     if (hr == NULL) {
       if (Universe::heap()->is_in_permanent(obj))
@@ -1482,7 +1497,7 @@
     else return is_obj_dead(obj, hr);
   }
 
-  bool is_obj_ill(const oop obj) {
+  bool is_obj_ill(const oop obj) const {
     const HeapRegion* hr = heap_region_containing(obj);
     if (hr == NULL) {
       if (Universe::heap()->is_in_permanent(obj))

--- a/hotspot/src/share/vm/gc_implementation/g1/g1MarkSweep.cpp	Tue Jun 14 10:33:43 2011 -0400
+++ b/hotspot/src/share/vm/gc_implementation/g1/g1MarkSweep.cpp	Tue Jun 14 11:01:10 2011 -0700
@@ -84,11 +84,6 @@
 
   mark_sweep_phase1(marked_for_unloading, clear_all_softrefs);
 
-  if (VerifyDuringGC) {
-      G1CollectedHeap* g1h = G1CollectedHeap::heap();
-      g1h->checkConcurrentMark();
-  }
-
   mark_sweep_phase2();
 
   // Don't add any more derived pointers during phase3
@@ -179,6 +174,29 @@
 
   assert(GenMarkSweep::_marking_stack.is_empty(),
          "stack should be empty by now");
+
+  if (VerifyDuringGC) {
+    HandleMark hm;  // handle scope
+    COMPILER2_PRESENT(DerivedPointerTableDeactivate dpt_deact);
+    gclog_or_tty->print(" VerifyDuringGC:(full)[Verifying ");
+    Universe::heap()->prepare_for_verify();
+    // Note: we can verify only the heap here. When an object is
+    // marked, the previous value of the mark word (including
+    // identity hash values, ages, etc) is preserved, and the mark
+    // word is set to markOop::marked_value - effectively removing
+    // any hash values from the mark word. These hash values are
+    // used when verifying the dictionaries and so removing them
+    // from the mark word can make verification of the dictionaries
+    // fail. At the end of the GC, the orginal mark word values
+    // (including hash values) are restored to the appropriate
+    // objects.
+    Universe::heap()->verify(/* allow dirty */ true,
+                             /* silent      */ false,
+                             /* option      */ VerifyOption_G1UseMarkWord);
+
+    G1CollectedHeap* g1h = G1CollectedHeap::heap();
+    gclog_or_tty->print_cr("]");
+  }
 }
 
 class G1PrepareCompactClosure: public HeapRegionClosure {

--- a/hotspot/src/share/vm/gc_implementation/g1/heapRegion.cpp	Tue Jun 14 10:33:43 2011 -0400
+++ b/hotspot/src/share/vm/gc_implementation/g1/heapRegion.cpp	Tue Jun 14 11:01:10 2011 -0700
@@ -60,13 +60,14 @@
   oop _containing_obj;
   bool _failures;
   int _n_failures;
-  bool _use_prev_marking;
+  VerifyOption _vo;
 public:
-  // use_prev_marking == true  -> use "prev" marking information,
-  // use_prev_marking == false -> use "next" marking information
-  VerifyLiveClosure(G1CollectedHeap* g1h, bool use_prev_marking) :
+  // _vo == UsePrevMarking -> use "prev" marking information,
+  // _vo == UseNextMarking -> use "next" marking information,
+  // _vo == UseMarkWord    -> use mark word from object header.
+  VerifyLiveClosure(G1CollectedHeap* g1h, VerifyOption vo) :
     _g1h(g1h), _bs(NULL), _containing_obj(NULL),
-    _failures(false), _n_failures(0), _use_prev_marking(use_prev_marking)
+    _failures(false), _n_failures(0), _vo(vo)
   {
     BarrierSet* bs = _g1h->barrier_set();
     if (bs->is_a(BarrierSet::CardTableModRef))
@@ -95,14 +96,14 @@
 
   template <class T> void do_oop_work(T* p) {
     assert(_containing_obj != NULL, "Precondition");
-    assert(!_g1h->is_obj_dead_cond(_containing_obj, _use_prev_marking),
+    assert(!_g1h->is_obj_dead_cond(_containing_obj, _vo),
            "Precondition");
     T heap_oop = oopDesc::load_heap_oop(p);
     if (!oopDesc::is_null(heap_oop)) {
       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
       bool failed = false;
       if (!_g1h->is_in_closed_subset(obj) ||
-          _g1h->is_obj_dead_cond(obj, _use_prev_marking)) {
+          _g1h->is_obj_dead_cond(obj, _vo)) {
         if (!_failures) {
           gclog_or_tty->print_cr("");
           gclog_or_tty->print_cr("----------");
@@ -735,20 +736,20 @@
 
 void HeapRegion::verify(bool allow_dirty) const {
   bool dummy = false;
-  verify(allow_dirty, /* use_prev_marking */ true, /* failures */ &dummy);
+  verify(allow_dirty, VerifyOption_G1UsePrevMarking, /* failures */ &dummy);
 }
 
 // This really ought to be commoned up into OffsetTableContigSpace somehow.
 // We would need a mechanism to make that code skip dead objects.
 
 void HeapRegion::verify(bool allow_dirty,
-                        bool use_prev_marking,
+                        VerifyOption vo,
                         bool* failures) const {
   G1CollectedHeap* g1 = G1CollectedHeap::heap();
   *failures = false;
   HeapWord* p = bottom();
   HeapWord* prev_p = NULL;
-  VerifyLiveClosure vl_cl(g1, use_prev_marking);
+  VerifyLiveClosure vl_cl(g1, vo);
   bool is_humongous = isHumongous();
   bool do_bot_verify = !is_young();
   size_t object_num = 0;
@@ -773,7 +774,7 @@
       return;
     }
 
-    if (!g1->is_obj_dead_cond(obj, this, use_prev_marking)) {
+    if (!g1->is_obj_dead_cond(obj, this, vo)) {
       if (obj->is_oop()) {
         klassOop klass = obj->klass();
         if (!klass->is_perm()) {

--- a/hotspot/src/share/vm/gc_implementation/g1/heapRegion.hpp	Tue Jun 14 10:33:43 2011 -0400
+++ b/hotspot/src/share/vm/gc_implementation/g1/heapRegion.hpp	Tue Jun 14 11:01:10 2011 -0700
@@ -855,14 +855,20 @@
   void print() const;
   void print_on(outputStream* st) const;
 
-  // use_prev_marking == true  -> use "prev" marking information,
-  // use_prev_marking == false -> use "next" marking information
+  // vo == UsePrevMarking  -> use "prev" marking information,
+  // vo == UseNextMarking -> use "next" marking information
+  // vo == UseMarkWord    -> use the mark word in the object header
+  //
   // NOTE: Only the "prev" marking information is guaranteed to be
   // consistent most of the time, so most calls to this should use
-  // use_prev_marking == true. Currently, there is only one case where
-  // this is called with use_prev_marking == false, which is to verify
-  // the "next" marking information at the end of remark.
-  void verify(bool allow_dirty, bool use_prev_marking, bool *failures) const;
+  // vo == UsePrevMarking.
+  // Currently, there is only one case where this is called with
+  // vo == UseNextMarking, which is to verify the "next" marking
+  // information at the end of remark.
+  // Currently there is only one place where this is called with
+  // vo == UseMarkWord, which is to verify the marking during a
+  // full GC.
+  void verify(bool allow_dirty, VerifyOption vo, bool *failures) const;
 
   // Override; it uses the "prev" marking information
   virtual void verify(bool allow_dirty) const;

--- a/hotspot/src/share/vm/gc_implementation/parallelScavenge/parallelScavengeHeap.cpp	Tue Jun 14 10:33:43 2011 -0400
+++ b/hotspot/src/share/vm/gc_implementation/parallelScavenge/parallelScavengeHeap.cpp	Tue Jun 14 11:01:10 2011 -0700
@@ -901,7 +901,7 @@
 }
 
 
-void ParallelScavengeHeap::verify(bool allow_dirty, bool silent, bool option /* ignored */) {
+void ParallelScavengeHeap::verify(bool allow_dirty, bool silent, VerifyOption option /* ignored */) {
   // Why do we need the total_collections()-filter below?
   if (total_collections() > 0) {
     if (!silent) {

--- a/hotspot/src/share/vm/gc_implementation/parallelScavenge/parallelScavengeHeap.hpp	Tue Jun 14 10:33:43 2011 -0400
+++ b/hotspot/src/share/vm/gc_implementation/parallelScavenge/parallelScavengeHeap.hpp	Tue Jun 14 11:01:10 2011 -0700
@@ -253,7 +253,7 @@
   virtual void gc_threads_do(ThreadClosure* tc) const;
   virtual void print_tracing_info() const;
 
-  void verify(bool allow_dirty, bool silent, bool /* option */);
+  void verify(bool allow_dirty, bool silent, VerifyOption option /* ignored */);
 
   void print_heap_change(size_t prev_used);
 

--- a/hotspot/src/share/vm/gc_interface/collectedHeap.hpp	Tue Jun 14 10:33:43 2011 -0400
+++ b/hotspot/src/share/vm/gc_interface/collectedHeap.hpp	Tue Jun 14 11:01:10 2011 -0700
@@ -606,7 +606,7 @@
   virtual void print_tracing_info() const = 0;
 
   // Heap verification
-  virtual void verify(bool allow_dirty, bool silent, bool option) = 0;
+  virtual void verify(bool allow_dirty, bool silent, VerifyOption option) = 0;
 
   // Non product verification and debugging.
 #ifndef PRODUCT

--- a/hotspot/src/share/vm/memory/genCollectedHeap.cpp	Tue Jun 14 10:33:43 2011 -0400
+++ b/hotspot/src/share/vm/memory/genCollectedHeap.cpp	Tue Jun 14 11:01:10 2011 -0700
@@ -1260,7 +1260,7 @@
   return _gens[level]->gc_stats();
 }
 
-void GenCollectedHeap::verify(bool allow_dirty, bool silent, bool option /* ignored */) {
+void GenCollectedHeap::verify(bool allow_dirty, bool silent, VerifyOption option /* ignored */) {
   if (!silent) {
     gclog_or_tty->print("permgen ");
   }

--- a/hotspot/src/share/vm/memory/genCollectedHeap.hpp	Tue Jun 14 10:33:43 2011 -0400
+++ b/hotspot/src/share/vm/memory/genCollectedHeap.hpp	Tue Jun 14 11:01:10 2011 -0700
@@ -361,7 +361,7 @@
   void prepare_for_verify();
 
   // Override.
-  void verify(bool allow_dirty, bool silent, bool /* option */);
+  void verify(bool allow_dirty, bool silent, VerifyOption option);
 
   // Override.
   void print() const;

--- a/hotspot/src/share/vm/memory/universe.cpp	Tue Jun 14 10:33:43 2011 -0400
+++ b/hotspot/src/share/vm/memory/universe.cpp	Tue Jun 14 11:01:10 2011 -0700
@@ -1278,7 +1278,7 @@
   st->print_cr("}");
 }
 
-void Universe::verify(bool allow_dirty, bool silent, bool option) {
+void Universe::verify(bool allow_dirty, bool silent, VerifyOption option) {
   if (SharedSkipVerify) {
     return;
   }

--- a/hotspot/src/share/vm/memory/universe.hpp	Tue Jun 14 10:33:43 2011 -0400
+++ b/hotspot/src/share/vm/memory/universe.hpp	Tue Jun 14 11:01:10 2011 -0700
@@ -109,6 +109,14 @@
   bool    _use_implicit_null_checks;
 };
 
+enum VerifyOption {
+      VerifyOption_Default = 0,
+
+      // G1
+      VerifyOption_G1UsePrevMarking = VerifyOption_Default,
+      VerifyOption_G1UseNextMarking = VerifyOption_G1UsePrevMarking + 1,
+      VerifyOption_G1UseMarkWord    = VerifyOption_G1UseNextMarking + 1
+};
 
 class Universe: AllStatic {
   // Ugh.  Universe is much too friendly.
@@ -404,7 +412,8 @@
 
   // Debugging
   static bool verify_in_progress() { return _verify_in_progress; }
-  static void verify(bool allow_dirty = true, bool silent = false, bool option = true);
+  static void verify(bool allow_dirty = true, bool silent = false,
+                     VerifyOption option = VerifyOption_Default );
   static int  verify_count()                  { return _verify_count; }
   static void print();
   static void print_on(outputStream* st);