--- old/src/hotspot/share/runtime/objectMonitor.hpp	2019-04-18 22:07:22.696307022 -0400
+++ new/src/hotspot/share/runtime/objectMonitor.hpp	2019-04-18 22:07:21.892307035 -0400
@@ -150,7 +150,7 @@
                         sizeof(volatile markOop) + sizeof(void * volatile) +
                         sizeof(ObjectMonitor *));
  protected:                         // protected for JvmtiRawMonitor
-  // Used by async monitor deflation as a marker in the _owner field:
+  // Used by async deflation as a marker in the _owner field:
   #define DEFLATER_MARKER reinterpret_cast<void*>(-1)
   void *  volatile _owner;          // pointer to owning thread OR BasicLock
   volatile jlong _previous_owner_tid;  // thread id of the previous owner of the monitor
@@ -349,7 +349,7 @@
   int       TrySpin(Thread * Self);
   void      ExitEpilog(Thread * Self, ObjectWaiter * Wakee);
   bool      ExitSuspendEquivalent(JavaThread * Self);
-  void      install_displaced_markword_in_object();
+  void      install_displaced_markword_in_object(const oop obj);
 };
 
 // A helper object for managing an ObjectMonitor*'s ref_count. There
@@ -372,4 +372,15 @@
   void set_om_ptr(ObjectMonitor * om_ptr);
 };
 
+// Macro to use guarantee() for more strict AsyncDeflateIdleMonitors
+// checks and assert() otherwise.
+#define ADIM_guarantee(p, ...)       \
+  do {                               \
+    if (AsyncDeflateIdleMonitors) {  \
+      guarantee(p, __VA_ARGS__);     \
+    } else {                         \
+      assert(p, __VA_ARGS__);        \
+    }                                \
+  } while (0)
+
 #endif // SHARE_RUNTIME_OBJECTMONITOR_HPP