[GR-67752] Small cleanups for "Cleaner"-related code.

PullRequest: graal/21610

Author: christianhaeubl

substratevm/src/com.oracle.svm.core/src/com/oracle/svm/core/heap/ReferenceHandler.java

@@ -33,6 +33,8 @@
 import com.oracle.svm.core.stack.StackOverflowCheck;
 import com.oracle.svm.core.util.VMError;
 
+import jdk.internal.ref.CleanerFactory;
+
 public final class ReferenceHandler {
     public static boolean useDedicatedThread() {
         int automaticReferenceHandling = IsolateArgumentParser.getOptionIndex(SubstrateOptions.ConcealedOptions.AutomaticReferenceHandling);
@@ -68,7 +70,7 @@ static void processCleaners() {
         // Note: (sun.misc|jdk.internal).Cleaner objects are invoked in pending reference processing
 
         // Process the JDK's common cleaner, additional cleaners start their own threads
-        Target_java_lang_ref_Cleaner commonCleaner = Target_jdk_internal_ref_CleanerFactory.cleaner();
+        Target_java_lang_ref_Cleaner commonCleaner = SubstrateUtil.cast(CleanerFactory.cleaner(), Target_java_lang_ref_Cleaner.class);
         Reference<?> ref = commonCleaner.impl.queue.poll();
         while (ref != null) {
             try {

substratevm/src/com.oracle.svm.core/src/com/oracle/svm/core/heap/Target_java_lang_ref_Cleaner.java

@@ -44,13 +44,7 @@
 @TargetClass(className = "java.lang.ref.Cleaner")
 public final class Target_java_lang_ref_Cleaner {
     @Alias//
-    public Target_jdk_internal_ref_CleanerImpl impl;
-}
-
-@TargetClass(className = "jdk.internal.ref.CleanerFactory")
-final class Target_jdk_internal_ref_CleanerFactory {
-    @Alias
-    public static native Target_java_lang_ref_Cleaner cleaner();
+    Target_jdk_internal_ref_CleanerImpl impl;
 }
 
 @TargetClass(className = "java.lang.ref.Cleaner$Cleanable")