--- a/hotspot/src/share/vm/gc_implementation/g1/heapRegion.inline.hpp	Mon Jul 07 10:12:40 2014 +0200
+++ b/hotspot/src/share/vm/gc_implementation/g1/heapRegion.inline.hpp	Mon Jul 07 12:37:11 2014 +0200
@@ -93,27 +93,18 @@
 
 inline bool
 HeapRegion::block_is_obj(const HeapWord* p) const {
-  G1CollectedHeap* g1h = G1CollectedHeap::heap();
-  return !g1h->is_obj_dead(oop(p), this);
+  return p < top();
 }
 
 inline size_t
 HeapRegion::block_size(const HeapWord *addr) const {
-  // Old regions' dead objects may have dead classes
-  // We need to find the next live object in some other
-  // manner than getting the oop size
-  G1CollectedHeap* g1h = G1CollectedHeap::heap();
-  if (g1h->is_obj_dead(oop(addr), this)) {
-    HeapWord* next = g1h->concurrent_mark()->prevMarkBitMap()->
-        getNextMarkedWordAddress(addr, prev_top_at_mark_start());
-
-    assert(next > addr, "must get the next live object");
-
-    return pointer_delta(next, addr);
-  } else if (addr == top()) {
+  const HeapWord* current_top = top();
+  if (addr < current_top) {
+    return oop(addr)->size();
+  } else {
+    assert(addr == current_top, "just checking");
     return pointer_delta(end(), addr);
   }
-  return oop(addr)->size();
 }
 
 inline HeapWord* HeapRegion::par_allocate_no_bot_updates(size_t word_size) {