8307392: [Lilliput] Revert deflation of dead object's monitors

Reviewed-by: shade

Author: rkennke

src/hotspot/share/gc/shared/oopStorage.inline.hpp

@@ -29,7 +29,6 @@
 
 #include "memory/allocation.hpp"
 #include "oops/oop.hpp"
-#include "runtime/objectMonitor.hpp"
 #include "runtime/safepoint.hpp"
 #include "utilities/align.hpp"
 #include "utilities/count_trailing_zeros.hpp"
@@ -263,7 +262,6 @@ class OopStorage::IfAliveFn {
       if (_is_alive->do_object_b(v)) {
         result = _f(ptr);
       } else {
-        ObjectMonitor::maybe_deflate_dead(ptr);
         *ptr = nullptr;            // Clear dead value.
       }
     }

src/hotspot/share/gc/shared/weakProcessor.inline.hpp

@@ -65,7 +65,6 @@ class WeakProcessor::CountingClosure : public Closure {
       _keep_alive->do_oop(p);
       ++_live;
     } else {
-      ObjectMonitor::maybe_deflate_dead(p);
       *p = nullptr;
       ++_new_dead;
     }

src/hotspot/share/runtime/objectMonitor.cpp

@@ -600,22 +600,6 @@ bool ObjectMonitor::deflate_monitor() {
   return true;  // Success, ObjectMonitor has been deflated.
 }
 
-// We might access the dead object headers for parsable heap walk, make sure
-// headers are in correct shape, e.g. monitors deflated.
-void ObjectMonitor::maybe_deflate_dead(oop* p) {
-  oop obj = *p;
-  assert(obj != NULL, "must not yet been cleared");
-  markWord mark = obj->mark();
-  if (mark.has_monitor()) {
-    ObjectMonitor* monitor = mark.monitor();
-    if (p == monitor->_object.ptr_raw()) {
-      assert(monitor->object_peek() == obj, "lock object must match");
-      markWord dmw = monitor->header();
-      obj->set_mark(dmw);
-    }
-  }
-}
-
 // Install the displaced mark word (dmw) of a deflating ObjectMonitor
 // into the header of the object associated with the monitor. This
 // idempotent method is called by a thread that is deflating a

src/hotspot/share/runtime/objectMonitor.hpp

@@ -343,8 +343,6 @@ class ObjectMonitor : public CHeapObj<mtObjectMonitor> {
   // Use the following at your own risk
   intx      complete_exit(JavaThread* current);
 
-  static void maybe_deflate_dead(oop* p);
-
  private:
   void      AddWaiter(ObjectWaiter* waiter);
   void      INotify(JavaThread* current);