8264783: G1 BOT verification should not verify beyond allocation threshold

Reviewed-by: mli, ayang

Author: Thomas Schatzl

src/hotspot/share/gc/g1/g1BlockOffsetTable.cpp

@@ -327,7 +327,8 @@ void G1BlockOffsetTablePart::alloc_block_work(HeapWord** threshold_, size_t* ind
 void G1BlockOffsetTablePart::verify() const {
   assert(_hr->bottom() < _hr->top(), "Only non-empty regions should be verified.");
   size_t start_card = _bot->index_for(_hr->bottom());
-  size_t end_card = _bot->index_for(_hr->top() - 1);
+  // Do not verify beyond the BOT allocation threshold.
+  size_t end_card = MIN2(_bot->index_for(_hr->top() - 1), _next_offset_index - 1);
 
   for (size_t current_card = start_card; current_card < end_card; current_card++) {
     u_char entry = _bot->offset_array(current_card);

src/hotspot/share/gc/g1/heapRegion.cpp

@@ -721,7 +721,7 @@ void HeapRegion::verify(VerifyOption vo,
     p += obj_size;
   }
 
-  if (!is_young() && !is_empty()) {
+  if (!is_empty()) {
     _bot_part.verify();
   }