Only apply special Cleaner behaviour to jdk<9

Author: gilles-duboscq

espresso/src/com.oracle.truffle.espresso/src/com/oracle/truffle/espresso/descriptors/EspressoSymbols.java

@@ -323,7 +323,6 @@ public static void ensureInitialized() {
         public static final Symbol<Type> java_lang_ref_Reference$Lock = SYMBOLS.putType("Ljava/lang/ref/Reference$Lock;");
 
         public static final Symbol<Type> sun_misc_Cleaner = SYMBOLS.putType("Lsun/misc/Cleaner;");
-        public static final Symbol<Type> jdk_internal_ref_Cleaner = SYMBOLS.putType("Ljdk/internal/ref/Cleaner;");
 
         public static final Symbol<Type> java_lang_StackTraceElement = SYMBOLS.putType("Ljava/lang/StackTraceElement;");
         public static final Symbol<Type> java_lang_StackTraceElement_array = SYMBOLS.putType("[Ljava/lang/StackTraceElement;");

espresso/src/com.oracle.truffle.espresso/src/com/oracle/truffle/espresso/meta/Meta.java

@@ -976,15 +976,12 @@ public Meta(EspressoContext context) {
                         .klass();
         sun_reflect_ConstantPool_constantPoolOop = sun_reflect_ConstantPool.requireDeclaredField(Names.constantPoolOop, Types.java_lang_Object);
 
-        sun_misc_Cleaner = diff() //
-                        .klass(VERSION_8_OR_LOWER, Types.sun_misc_Cleaner) //
-                        .klass(VERSION_9_OR_HIGHER, Types.jdk_internal_ref_Cleaner) //
-                        .klass();
-
         if (getJavaVersion().java8OrEarlier()) {
             java_lang_ref_Reference_pending = java_lang_ref_Reference.requireDeclaredField(Names.pending, Types.java_lang_ref_Reference);
+            sun_misc_Cleaner = knownKlass(Types.sun_misc_Cleaner);
         } else {
             java_lang_ref_Reference_pending = null;
+            sun_misc_Cleaner = null;
         }
         java_lang_ref_Reference_lock = diff() //
                         .field(VERSION_8_OR_LOWER, Names.lock, Types.java_lang_ref_Reference$Lock) //

espresso/src/com.oracle.truffle.espresso/src/com/oracle/truffle/espresso/runtime/EspressoReferenceDrainer.java

@@ -196,12 +196,14 @@ private void doWaitForReferencePendingList() {
 
     private void casNextIfNullAndMaybeClear(EspressoReference wrapper) {
         StaticObject ref = wrapper.getGuestReference();
-        // Cleaner references extends PhantomReference but are cleared.
-        // See HotSpot's ReferenceProcessor::process_discovered_references in referenceProcessor.cpp
-        if (InterpreterToVM.instanceOf(ref, getMeta().sun_misc_Cleaner)) {
+        Meta meta = getMeta();
+        assert meta.sun_misc_Cleaner != null || getJavaVersion().java9OrLater();
+        if (meta.sun_misc_Cleaner != null && InterpreterToVM.instanceOf(ref, meta.sun_misc_Cleaner)) {
+            // Cleaner references extends PhantomReference but are cleared.
+            // See HotSpot's ReferenceProcessor::process_discovered_references in referenceProcessor.cpp
             wrapper.clear();
         }
-        getMeta().java_lang_ref_Reference_next.compareAndSwapObject(ref, StaticObject.NULL, ref);
+        meta.java_lang_ref_Reference_next.compareAndSwapObject(ref, StaticObject.NULL, ref);
     }
 
     private static final class ExitTLA extends ThreadLocalAction {