8319778: Remove unreachable code in ObjectSynchronizer::exit

Reviewed-by: rkennke, dholmes, pchilanomate, dcubed

src/hotspot/share/runtime/lockStack.hpp

@@ -81,9 +81,6 @@ public:
   // Pushes an oop on this lock-stack.
   inline void push(oop o);
 
-  // Pops an oop from this lock-stack.
-  inline oop pop();
-
   // Removes an oop from an arbitrary location of this lock-stack.
   inline void remove(oop o);
 

src/hotspot/share/runtime/lockStack.inline.hpp

@@ -68,19 +68,6 @@ inline void LockStack::push(oop o) {
   verify("post-push");
 }
 
-inline oop LockStack::pop() {
-  verify("pre-pop");
-  assert(to_index(_top) > 0, "underflow, probably unbalanced push/pop");
-  _top -= oopSize;
-  oop o = _base[to_index(_top)];
-#ifdef ASSERT
-  _base[to_index(_top)] = nullptr;
-#endif
-  assert(!contains(o), "entries must be unique: " PTR_FORMAT, p2i(o));
-  verify("post-pop");
-  return o;
-}
-
 inline void LockStack::remove(oop o) {
   verify("pre-remove");
   assert(contains(o), "entry must be present: " PTR_FORMAT, p2i(o));

src/hotspot/share/runtime/synchronizer.cpp

@@ -599,13 +599,7 @@ void ObjectSynchronizer::exit(oop object, BasicLock* lock, JavaThread* current)
   // The ObjectMonitor* can't be async deflated until ownership is
   // dropped inside exit() and the ObjectMonitor* must be !is_busy().
   ObjectMonitor* monitor = inflate(current, object, inflate_cause_vm_internal);
-  if (LockingMode == LM_LIGHTWEIGHT && monitor->is_owner_anonymous()) {
+  assert(!monitor->is_owner_anonymous(), "must not be");
-    // It must be owned by us. Pop lock object from lock stack.
-    LockStack& lock_stack = current->lock_stack();
-    oop popped = lock_stack.pop();
-    assert(popped == object, "must be owned by this thread");
-    monitor->set_owner_from_anonymous(current);
-  }
   monitor->exit(current);
 }