--- old/src/hotspot/share/runtime/objectMonitor.hpp	2020-01-28 14:36:32.000000000 -0500
+++ new/src/hotspot/share/runtime/objectMonitor.hpp	2020-01-28 14:36:32.000000000 -0500
@@ -232,7 +232,17 @@
   intptr_t  is_entered(Thread* current) const;
 
   void*     owner() const;
-  void      set_owner(void* owner);
+  // Clear _owner field; current value must match old_value.
+  void      release_clear_owner(void* old_value);
+  // Simply set _owner field to new_value; current value must match old_value.
+  void      set_owner_from(void* old_value, void* new_value);
+  // Simply set _owner field to self; current value must match basic_lock_p.
+  void      set_owner_from_BasicLock(void* basic_lock_p, Thread* self);
+  // Try to set _owner field to new_value if the current value matches
+  // old_value. Otherwise, does not change the _owner field. Returns
+  // the prior value of the _owner field. try_set_owner_from() provides:
+  //   <fence> compare-and-exchange <membar StoreLoad|StoreStore>
+  void*     try_set_owner_from(void* old_value, void* new_value);
 
   jint      waiters() const;