8340838: Clean up MutableCallSite to use explicit release fence instead of AtomicInteger

Reviewed-by: jrose, redestad, shade

Author: liach

src/java.base/share/classes/java/lang/invoke/MutableCallSite.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2008, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2008, 2024, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -26,7 +26,8 @@
 package java.lang.invoke;
 
 import java.util.Objects;
-import java.util.concurrent.atomic.AtomicInteger;
+
+import static java.lang.invoke.MethodHandleStatics.UNSAFE;
 
 /**
  * A {@code MutableCallSite} is a {@link CallSite} whose target variable
@@ -274,11 +275,10 @@ public final MethodHandle dynamicInvoker() {
      */
     public static void syncAll(MutableCallSite[] sites) {
         if (sites.length == 0)  return;
-        STORE_BARRIER.lazySet(0);
+        UNSAFE.storeFence();
         for (MutableCallSite site : sites) {
             Objects.requireNonNull(site); // trigger NPE on first null
         }
         // FIXME: NYI
     }
-    private static final AtomicInteger STORE_BARRIER = new AtomicInteger();
 }