8145442: Add the facility to verify remembered sets for G1

Summary: Implement remembered sets verification for G1 with option VerifyRememberedSets
Reviewed-by: jmasa, mgerdin

src/share/vm/gc_implementation/g1/g1CollectedHeap.cpp

@@ -3839,6 +3839,16 @@ G1CollectedHeap::cleanup_surviving_young_words() {
   _surviving_young_words = NULL;
 }
 
+class VerifyRegionRemSetClosure : public HeapRegionClosure {
+  public:
+    bool doHeapRegion(HeapRegion* hr) {
+      if (!hr->continuesHumongous()) {
+        hr->verify_rem_set();
+      }
+      return false;
+    }
+};
+
 #ifdef ASSERT
 class VerifyCSetClosure: public HeapRegionClosure {
 public:
@@ -4015,6 +4025,14 @@ G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
       increment_total_collections(false /* full gc */);
       increment_gc_time_stamp();
 
+      if (VerifyRememberedSets) {
+        if (!VerifySilently) {
+          gclog_or_tty->print_cr("[Verifying RemSets before GC]");
+        }
+        VerifyRegionRemSetClosure v_cl;
+        heap_region_iterate(&v_cl);
+      }
+
       verify_before_gc();
       check_bitmaps("GC Start");
 
@@ -4246,6 +4264,14 @@ G1CollectedHeap::do_collection_pause_at_safepoint(double target_pause_time_ms) {
         // scanning cards (see CR 7039627).
         increment_gc_time_stamp();
 
+        if (VerifyRememberedSets) {
+          if (!VerifySilently) {
+            gclog_or_tty->print_cr("[Verifying RemSets after GC]");
+          }
+          VerifyRegionRemSetClosure v_cl;
+          heap_region_iterate(&v_cl);
+        }
+
         verify_after_gc();
         check_bitmaps("GC End");
 

src/share/vm/gc_implementation/g1/heapRegion.cpp

@@ -639,8 +639,8 @@ void HeapRegion::print_on(outputStream* st) const {
   G1OffsetTableContigSpace::print_on(st);
 }
 
-class VerifyLiveClosure: public OopClosure {
-private:
+class G1VerificationClosure : public OopClosure {
+protected:
   G1CollectedHeap* _g1h;
   CardTableModRefBS* _bs;
   oop _containing_obj;
@@ -651,7 +651,7 @@ public:
   // _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) :
+  G1VerificationClosure(G1CollectedHeap* g1h, VerifyOption vo) :
     _g1h(g1h), _bs(NULL), _containing_obj(NULL),
     _failures(false), _n_failures(0), _vo(vo)
   {
@@ -667,9 +667,6 @@ public:
   bool failures() { return _failures; }
   int n_failures() { return _n_failures; }
 
-  virtual void do_oop(narrowOop* p) { do_oop_work(p); }
-  virtual void do_oop(      oop* p) { do_oop_work(p); }
-
   void print_object(outputStream* out, oop obj) {
 #ifdef PRODUCT
     Klass* k = obj->klass();
@@ -679,19 +676,31 @@ public:
     obj->print_on(out);
 #endif // PRODUCT
   }
+};
+
+class VerifyLiveClosure : public G1VerificationClosure {
+public:
+  VerifyLiveClosure(G1CollectedHeap* g1h, VerifyOption vo) : G1VerificationClosure(g1h, vo) {}
+  virtual void do_oop(narrowOop* p) { do_oop_work(p); }
+  virtual void do_oop(oop* p) { do_oop_work(p); }
 
   template <class T>
   void do_oop_work(T* p) {
     assert(_containing_obj != NULL, "Precondition");
     assert(!_g1h->is_obj_dead_cond(_containing_obj, _vo),
-           "Precondition");
+      "Precondition");
+    verify_liveness(p);
+  }
+
+  template <class T>
+  void verify_liveness(T* p) {
     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, _vo)) {
         MutexLockerEx x(ParGCRareEvent_lock,
-                        Mutex::_no_safepoint_check_flag);
+          Mutex::_no_safepoint_check_flag);
 
         if (!_failures) {
           gclog_or_tty->cr();
@@ -727,50 +736,71 @@ public:
         failed = true;
         _n_failures++;
       }
+    }
+  }
+};
 
-      if (!_g1h->full_collection() || G1VerifyRSetsDuringFullGC) {
-        HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
-        HeapRegion* to   = _g1h->heap_region_containing(obj);
-        if (from != NULL && to != NULL &&
-            from != to &&
-            !to->isHumongous()) {
-          jbyte cv_obj = *_bs->byte_for_const(_containing_obj);
-          jbyte cv_field = *_bs->byte_for_const(p);
-          const jbyte dirty = CardTableModRefBS::dirty_card_val();
-
-          bool is_bad = !(from->is_young()
-                          || to->rem_set()->contains_reference(p)
-                          || !G1HRRSFlushLogBuffersOnVerify && // buffers were not flushed
-                              (_containing_obj->is_objArray() ?
-                                  cv_field == dirty
-                               : cv_obj == dirty || cv_field == dirty));
-          if (is_bad) {
-            MutexLockerEx x(ParGCRareEvent_lock,
-                            Mutex::_no_safepoint_check_flag);
-
-            if (!_failures) {
-              gclog_or_tty->cr();
-              gclog_or_tty->print_cr("----------");
-            }
-            gclog_or_tty->print_cr("Missing rem set entry:");
-            gclog_or_tty->print_cr("Field "PTR_FORMAT" "
-                                   "of obj "PTR_FORMAT", "
-                                   "in region "HR_FORMAT,
-                                   p, (void*) _containing_obj,
-                                   HR_FORMAT_PARAMS(from));
-            _containing_obj->print_on(gclog_or_tty);
-            gclog_or_tty->print_cr("points to obj "PTR_FORMAT" "
-                                   "in region "HR_FORMAT,
-                                   (void*) obj,
-                                   HR_FORMAT_PARAMS(to));
-            obj->print_on(gclog_or_tty);
-            gclog_or_tty->print_cr("Obj head CTE = %d, field CTE = %d.",
-                          cv_obj, cv_field);
+class VerifyRemSetClosure : public G1VerificationClosure {
+public:
+  VerifyRemSetClosure(G1CollectedHeap* g1h, VerifyOption vo) : G1VerificationClosure(g1h, vo) {}
+  virtual void do_oop(narrowOop* p) { do_oop_work(p); }
+  virtual void do_oop(oop* p) { do_oop_work(p); }
+
+  template <class T>
+  void do_oop_work(T* p) {
+    assert(_containing_obj != NULL, "Precondition");
+    assert(!_g1h->is_obj_dead_cond(_containing_obj, _vo),
+      "Precondition");
+    verify_remembered_set(p);
+  }
+
+  template <class T>
+  void verify_remembered_set(T* p) {
+    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;
+      HeapRegion* from = _g1h->heap_region_containing((HeapWord*)p);
+      HeapRegion* to   = _g1h->heap_region_containing(obj);
+      if (from != NULL && to != NULL &&
+          from != to &&
+          !to->isHumongous()) {
+        jbyte cv_obj = *_bs->byte_for_const(_containing_obj);
+        jbyte cv_field = *_bs->byte_for_const(p);
+        const jbyte dirty = CardTableModRefBS::dirty_card_val();
+
+        bool is_bad = !(from->is_young()
+                        || to->rem_set()->contains_reference(p)
+                        || !G1HRRSFlushLogBuffersOnVerify && // buffers were not flushed
+                            (_containing_obj->is_objArray() ?
+                                cv_field == dirty
+                             : cv_obj == dirty || cv_field == dirty));
+        if (is_bad) {
+          MutexLockerEx x(ParGCRareEvent_lock,
+                          Mutex::_no_safepoint_check_flag);
+
+          if (!_failures) {
+            gclog_or_tty->cr();
             gclog_or_tty->print_cr("----------");
-            gclog_or_tty->flush();
-            _failures = true;
-            if (!failed) _n_failures++;
           }
+          gclog_or_tty->print_cr("Missing rem set entry:");
+          gclog_or_tty->print_cr("Field "PTR_FORMAT" "
+                                 "of obj "PTR_FORMAT", "
+                                 "in region "HR_FORMAT,
+                                 p, (void*) _containing_obj,
+                                 HR_FORMAT_PARAMS(from));
+          _containing_obj->print_on(gclog_or_tty);
+          gclog_or_tty->print_cr("points to obj "PTR_FORMAT" "
+                                 "in region "HR_FORMAT,
+                                 (void*) obj,
+                                 HR_FORMAT_PARAMS(to));
+          obj->print_on(gclog_or_tty);
+          gclog_or_tty->print_cr("Obj head CTE = %d, field CTE = %d.",
+                        cv_obj, cv_field);
+          gclog_or_tty->print_cr("----------");
+          gclog_or_tty->flush();
+          _failures = true;
+          if (!failed) _n_failures++;
         }
       }
     }
@@ -787,6 +817,7 @@ void HeapRegion::verify(VerifyOption vo,
   HeapWord* p = bottom();
   HeapWord* prev_p = NULL;
   VerifyLiveClosure vl_cl(g1, vo);
+  VerifyRemSetClosure vr_cl(g1, vo);
   bool is_humongous = isHumongous();
   bool do_bot_verify = !is_young();
   size_t object_num = 0;
@@ -832,7 +863,23 @@ void HeapRegion::verify(VerifyOption vo,
           return;
         } else {
           vl_cl.set_containing_obj(obj);
-          obj->oop_iterate_no_header(&vl_cl);
+          if (!g1->full_collection() || G1VerifyRSetsDuringFullGC) {
+            // verify liveness and rem_set
+            vr_cl.set_containing_obj(obj);
+            G1Mux2Closure mux(&vl_cl, &vr_cl);
+            obj->oop_iterate_no_header(&mux);
+
+            if (vr_cl.failures()) {
+              *failures = true;
+            }
+            if (G1MaxVerifyFailures >= 0 &&
+              vr_cl.n_failures() >= G1MaxVerifyFailures) {
+              return;
+            }
+          } else {
+            // verify only liveness
+            obj->oop_iterate_no_header(&vl_cl);
+          }
           if (vl_cl.failures()) {
             *failures = true;
           }
@@ -842,7 +889,7 @@ void HeapRegion::verify(VerifyOption vo,
           }
         }
       } else {
-        gclog_or_tty->print_cr(PTR_FORMAT" no an oop", (void *)obj);
+        gclog_or_tty->print_cr(PTR_FORMAT" not an oop", (void *)obj);
         *failures = true;
         return;
       }
@@ -930,6 +977,46 @@ void HeapRegion::verify() const {
   verify(VerifyOption_G1UsePrevMarking, /* failures */ &dummy);
 }
 
+void HeapRegion::verify_rem_set(VerifyOption vo, bool* failures) const {
+  G1CollectedHeap* g1 = G1CollectedHeap::heap();
+  *failures = false;
+  HeapWord* p = bottom();
+  HeapWord* prev_p = NULL;
+  VerifyRemSetClosure vr_cl(g1, vo);
+  while (p < top()) {
+    oop obj = oop(p);
+    size_t obj_size = block_size(p);
+
+    if (!g1->is_obj_dead_cond(obj, this, vo)) {
+      if (obj->is_oop()) {
+        vr_cl.set_containing_obj(obj);
+        obj->oop_iterate_no_header(&vr_cl);
+
+        if (vr_cl.failures()) {
+          *failures = true;
+        }
+        if (G1MaxVerifyFailures >= 0 &&
+          vr_cl.n_failures() >= G1MaxVerifyFailures) {
+          return;
+        }
+      } else {
+        gclog_or_tty->print_cr(PTR_FORMAT " not an oop", p2i(obj));
+        *failures = true;
+        return;
+      }
+    }
+
+    prev_p = p;
+    p += obj_size;
+  }
+}
+
+void HeapRegion::verify_rem_set() const {
+  bool failures = false;
+  verify_rem_set(VerifyOption_G1UsePrevMarking, &failures);
+  guarantee(!failures, "HeapRegion RemSet verification failed");
+}
+
 // G1OffsetTableContigSpace code; copied from space.cpp.  Hope this can go
 // away eventually.
 

src/share/vm/gc_implementation/g1/heapRegion.hpp

@@ -779,6 +779,9 @@ class HeapRegion: public G1OffsetTableContigSpace {
 
   // Override; it uses the "prev" marking information
   virtual void verify() const;
+
+  void verify_rem_set(VerifyOption vo, bool *failures) const;
+  void verify_rem_set() const;
 };
 
 // HeapRegionClosure is used for iterating over regions.