8330981: ZGC: Should not dedup strings in the finalizer graph

Backport-of: 2f2dc2289bce47d8071a86215218f345cce71dba

Author: shipilev

src/hotspot/share/gc/x/xMark.cpp

@@ -367,8 +367,10 @@ void XMark::mark_and_follow(XMarkContext* context, XMarkStackEntry entry) {
       const oop obj = XOop::from_address(addr);
       follow_object(obj, finalizable);
 
-      // Try deduplicate
-      try_deduplicate(context, obj);
+      if (!finalizable) {
+        // Try deduplicate
+        try_deduplicate(context, obj);
+      }
     }
   }
 }

src/hotspot/share/gc/z/zMark.cpp

@@ -457,8 +457,10 @@ void ZMark::mark_and_follow(ZMarkContext* context, ZMarkStackEntry entry) {
       const oop obj = to_oop(addr);
       follow_object(obj, finalizable);
 
-      // Try deduplicate
-      try_deduplicate(context, obj);
+      if (!finalizable) {
+        // Try deduplicate
+        try_deduplicate(context, obj);
+      }
     }
   }
 }