From 03d992728e27bd3dcd00d1af8a7b7179281e626f Mon Sep 17 00:00:00 2001
From: Coleen Phillimore <coleenp@openjdk.org>
Date: Tue, 20 Dec 2022 13:21:50 +0000
Subject: [PATCH] 8298061:
 vmTestbase/nsk/sysdict/vm/stress/btree/btree012/btree012.java failed with
 "fatal error: refcount has gone to zero"

Reviewed-by: iklam, dholmes
---
 src/hotspot/share/classfile/placeholders.hpp | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/src/hotspot/share/classfile/placeholders.hpp b/src/hotspot/share/classfile/placeholders.hpp
index 4e05136e00b..c44e3897b39 100644
--- a/src/hotspot/share/classfile/placeholders.hpp
+++ b/src/hotspot/share/classfile/placeholders.hpp
@@ -105,9 +105,11 @@ class PlaceholderEntry {
 
   Symbol*            supername()           const { return _supername; }
   void               set_supername(Symbol* supername) {
-    Symbol::maybe_decrement_refcount(_supername);
-    _supername = supername;
-    Symbol::maybe_increment_refcount(_supername);
+    if (supername != _supername) {
+      Symbol::maybe_decrement_refcount(_supername);
+      _supername = supername;
+      Symbol::maybe_increment_refcount(_supername);
+    }
   }
   void               clear_supername() {
     Symbol::maybe_decrement_refcount(_supername);