6817419: G1: Enable extensive verification for humongous regions

Summary: Enabled full verification for humongous regions. Also made sure that the VerifyAfterGC works with deferred updates and G1HRRSFlushLogBuffersOnVerify.
Reviewed-by: tonyp

src/share/vm/gc_implementation/g1/concurrentG1Refine.cpp

@@ -145,14 +145,9 @@ void ConcurrentG1Refine::set_pya_restart() {
   if (G1RSBarrierUseQueue) {
     DirtyCardQueueSet& dcqs = JavaThread::dirty_card_queue_set();
     dcqs.abandon_logs();
-    if (_cg1rThread->do_traversal()) {
-      _pya = PYA_restart;
-    } else {
-      _cg1rThread->set_do_traversal(true);
-      // Reset the post-yield actions.
-      _pya = PYA_continue;
-      _last_pya = PYA_continue;
-    }
+    // Reset the post-yield actions.
+    _pya = PYA_continue;
+    _last_pya = PYA_continue;
   } else {
     _pya = PYA_restart;
   }

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

@@ -961,6 +961,7 @@ void G1CollectedHeap::do_collection(bool full, bool clear_all_soft_refs,
     if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
       HandleMark hm;  // Discard invalid handles created during verification
       gclog_or_tty->print(" VerifyAfterGC:");
+      prepare_for_verify();
       Universe::verify(false);
     }
     NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
@@ -2135,15 +2136,7 @@ public:
   bool doHeapRegion(HeapRegion* r) {
     guarantee(_par || r->claim_value() == HeapRegion::InitialClaimValue,
               "Should be unclaimed at verify points.");
-    if (r->isHumongous()) {
-      if (r->startsHumongous()) {
-        // Verify the single H object.
-        oop(r->bottom())->verify();
-        size_t word_sz = oop(r->bottom())->size();
-        guarantee(r->top() == r->bottom() + word_sz,
-                  "Only one object in a humongous region");
-      }
-    } else {
+    if (!r->continuesHumongous()) {
       VerifyObjsInRegionClosure not_dead_yet_cl(r);
       r->verify(_allow_dirty);
       r->object_iterate(&not_dead_yet_cl);
@@ -2195,6 +2188,7 @@ public:
     _g1h(g1h), _allow_dirty(allow_dirty) { }
 
   void work(int worker_i) {
+    HandleMark hm;
     VerifyRegionClosure blk(_allow_dirty, true);
     _g1h->heap_region_par_iterate_chunked(&blk, worker_i,
                                           HeapRegion::ParVerifyClaimValue);
@@ -2713,6 +2707,7 @@ G1CollectedHeap::do_collection_pause_at_safepoint(HeapRegion* popular_region) {
     if (VerifyAfterGC && total_collections() >= VerifyGCStartAt) {
       HandleMark hm;  // Discard invalid handles created during verification
       gclog_or_tty->print(" VerifyAfterGC:");
+      prepare_for_verify();
       Universe::verify(false);
     }
 
@@ -2844,6 +2839,12 @@ void G1CollectedHeap::forget_alloc_region_list() {
   while (_gc_alloc_region_list != NULL) {
     HeapRegion* r = _gc_alloc_region_list;
     assert(r->is_gc_alloc_region(), "Invariant.");
+    // We need HeapRegion::oops_on_card_seq_iterate_careful() to work on
+    // newly allocated data in order to be able to apply deferred updates
+    // before the GC is done for verification purposes (i.e to allow
+    // G1HRRSFlushLogBuffersOnVerify). It's safe thing to do after the
+    // collection.
+    r->ContiguousSpace::set_saved_mark();
     _gc_alloc_region_list = r->next_gc_alloc_region();
     r->set_next_gc_alloc_region(NULL);
     r->set_is_gc_alloc_region(false);
@@ -3738,7 +3739,9 @@ protected:
   CardTableModRefBS* ctbs()                      { return _ct_bs; }
 
   void immediate_rs_update(HeapRegion* from, oop* p, int tid) {
-    _g1_rem->par_write_ref(from, p, tid);
+    if (!from->is_survivor()) {
+      _g1_rem->par_write_ref(from, p, tid);
+    }
   }
 
   void deferred_rs_update(HeapRegion* from, oop* p, int tid) {

src/share/vm/gc_implementation/g1/g1RemSet.cpp

@@ -716,8 +716,7 @@ public:
   bool doHeapRegion(HeapRegion* r) {
     if (!r->in_collection_set() &&
         !r->continuesHumongous() &&
-        !r->is_young() &&
-        !r->is_survivor()) {
+        !r->is_young()) {
       _update_rs_oop_cl.set_from(r);
       UpdateRSObjectClosure update_rs_obj_cl(&_update_rs_oop_cl);
 
@@ -854,7 +853,7 @@ void HRInto_G1RemSet::concurrentRefineOneCard(jbyte* card_ptr, int worker_i) {
   // before all the cards on the region are dirtied. This is unlikely,
   // and it doesn't happen often, but it can happen. So, the extra
   // check below filters out those cards.
-  if (r->is_young() || r->is_survivor()) {
+  if (r->is_young()) {
     return;
   }
   // While we are processing RSet buffers during the collection, we
@@ -1025,7 +1024,9 @@ void HRInto_G1RemSet::print_summary_info() {
   }
 }
 void HRInto_G1RemSet::prepare_for_verify() {
-  if (G1HRRSFlushLogBuffersOnVerify && VerifyBeforeGC && !_g1->full_collection()) {
+  if (G1HRRSFlushLogBuffersOnVerify &&
+      (VerifyBeforeGC || VerifyAfterGC)
+      &&  !_g1->full_collection()) {
     cleanupHRRS();
     _g1->set_refine_cte_cl_concurrency(false);
     if (SafepointSynchronize::is_at_safepoint()) {
@@ -1036,5 +1037,7 @@ void HRInto_G1RemSet::prepare_for_verify() {
     _cg1r->set_use_cache(false);
     updateRS(0);
     _cg1r->set_use_cache(cg1r_use_cache);
+
+    assert(JavaThread::dirty_card_queue_set().completed_buffers_num() == 0, "All should be consumed");
   }
 }