--- a/src/hotspot/share/prims/jvmtiExport.cpp	Wed Oct 17 18:31:48 2018 +0200
+++ b/src/hotspot/share/prims/jvmtiExport.cpp	Wed Oct 17 22:26:41 2018 +0200
@@ -1044,7 +1044,7 @@
  public:
    JvmtiObjectAllocEventMark(JavaThread *thread, oop obj) : JvmtiClassEventMark(thread, oop_to_klass(obj)) {
      _jobj = (jobject)to_jobject(obj);
-     _size = obj->size() * wordSize;
+     _size = Universe::heap()->obj_size(obj) * wordSize;
    };
    jobject jni_jobject() { return _jobj; }
    jlong size() { return _size; }

--- a/src/hotspot/share/prims/jvmtiTagMap.cpp	Wed Oct 17 18:31:48 2018 +0200
+++ b/src/hotspot/share/prims/jvmtiTagMap.cpp	Wed Oct 17 22:26:41 2018 +0200
@@ -105,7 +105,7 @@
   }
 
   inline bool equals(oop object) {
-    return object == object_peek();
+    return oopDesc::equals(object, object_peek());
   }
 
   inline JvmtiTagHashmapEntry* next() const        { return _next; }
@@ -186,6 +186,7 @@
 
     // shift right to get better distribution (as these bits will be zero
     // with aligned addresses)
+    key = Access<>::resolve(key);
     unsigned int addr = (unsigned int)(cast_from_oop<intptr_t>(key));
 #ifdef _LP64
     return (addr >> 3) % size;