Add subtyping to @AutomaticallyRegisteredImageSingleton-generated Fea…

…tures

The hierarchy of the generated InternalFeature classes now
mirrors the hierarchy of the singleton classes themselves.

substratevm/src/com.oracle.svm.core.posix/src/com/oracle/svm/core/posix/linux/LinuxThreadCpuTimeSupport.java

@@ -42,7 +42,7 @@
 import com.oracle.svm.core.util.TimeUtils;
 
 @AutomaticallyRegisteredImageSingleton(ThreadCpuTimeSupport.class)
-final class LinuxThreadCpuTimeSupport implements ThreadCpuTimeSupport {
+public class LinuxThreadCpuTimeSupport implements ThreadCpuTimeSupport {
 
     @Override
     @Uninterruptible(reason = "Called from uninterruptible code.", mayBeInlined = true)

substratevm/src/com.oracle.svm.core/src/com/oracle/svm/core/feature/AutomaticallyRegisteredImageSingleton.java

@@ -45,6 +45,10 @@
  * annotated class must not rely on other features being registered already, or other image
  * singletons being present already.
  *
+ * If both a class and a subclass are annotated with {@link AutomaticallyRegisteredImageSingleton}
+ * (and the subclass is not disabled by {@link #onlyWith}), only the subclass will be registered as
+ * an image singleton.
+ *
  * The requirements and restrictions of {@link AutomaticallyRegisteredFeature} apply also to this
  * annotation.
  */
@@ -54,14 +58,17 @@
 public @interface AutomaticallyRegisteredImageSingleton {
 
     /**
-     * The keys under which the singleton is registered in {@link ImageSingletons}. If no keys are
-     * specified, the annotated class itself is used as the key.
+     * The keys under which the singleton is registered in {@link ImageSingletons}. If the annotated
+     * class extends another annotated class, keys from the base class are inherited. If no keys are
+     * specified (or inherited), the annotated class itself is used as the key.
      */
     Class<?>[] value() default {};
 
     /**
      * Register only if all provided {@link BooleanSupplier} objects evaluate to true. If there are
      * no suppliers, the singleton is registered unconditionally.
+     *
+     * The values of this attribute are not inherited; a subclass may have fewer restrictions.
      */
     Class<? extends BooleanSupplier>[] onlyWith() default {};
 }

substratevm/src/com.oracle.svm.hosted/src/com/oracle/svm/hosted/jdk/JDKLibDirectoryFeature.java → substratevm/src/com.oracle.svm.hosted/src/com/oracle/svm/hosted/jdk/HostJDKLibDirectoryProvider.java

@@ -26,30 +26,19 @@
 
 import java.nio.file.Path;
 
-import org.graalvm.nativeimage.ImageSingletons;
 import org.graalvm.nativeimage.Platform;
 import org.graalvm.nativeimage.Platforms;
 import org.graalvm.nativeimage.impl.InternalPlatform;
 
-import com.oracle.svm.core.feature.AutomaticallyRegisteredFeature;
-import com.oracle.svm.core.feature.InternalFeature;
+import com.oracle.svm.core.feature.AutomaticallyRegisteredImageSingleton;
 
 @Platforms(InternalPlatform.PLATFORM_JNI.class)
-@AutomaticallyRegisteredFeature
-public final class JDKLibDirectoryFeature implements InternalFeature {
+@AutomaticallyRegisteredImageSingleton(JDKLibDirectoryProvider.class)
+public class HostJDKLibDirectoryProvider implements JDKLibDirectoryProvider {
     @Override
-    public void duringSetup(DuringSetupAccess access) {
-        if (!ImageSingletons.contains(JDKLibDirectoryProvider.class)) {
-            ImageSingletons.add(JDKLibDirectoryProvider.class, new HostJDKLibDirectoryProvider());
-        }
-    }
-
-    private static final class HostJDKLibDirectoryProvider implements JDKLibDirectoryProvider {
-        @Override
-        public Path getJDKLibDirectory() {
-            /* On Windows, JDK libraries are in `<java.home>\bin` directory. */
-            boolean isWindows = Platform.includedIn(Platform.WINDOWS.class);
-            return Path.of(System.getProperty("java.home"), isWindows ? "bin" : "lib");
-        }
+    public Path getJDKLibDirectory() {
+        /* On Windows, JDK libraries are in `<java.home>\bin` directory. */
+        boolean isWindows = Platform.includedIn(Platform.WINDOWS.class);
+        return Path.of(System.getProperty("java.home"), isWindows ? "bin" : "lib");
     }
 }

substratevm/src/com.oracle.svm.processor/src/com/oracle/svm/processor/AutomaticallyRegisteredImageSingletonProcessor.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2022, 2022, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2022, 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
@@ -25,6 +25,7 @@
 package com.oracle.svm.processor;
 
 import java.io.PrintWriter;
+import java.util.ArrayList;
 import java.util.HashSet;
 import java.util.List;
 import java.util.Set;
@@ -35,6 +36,8 @@
 import javax.lang.model.element.AnnotationMirror;
 import javax.lang.model.element.Element;
 import javax.lang.model.element.TypeElement;
+import javax.lang.model.type.DeclaredType;
+import javax.lang.model.type.TypeKind;
 import javax.lang.model.type.TypeMirror;
 
 import jdk.graal.compiler.processor.AbstractProcessor;
@@ -83,21 +86,32 @@ private void processElement(TypeElement annotatedType) {
                 out.println("@Platforms({" + platforms + "})");
             }
             out.println("@" + getSimpleName(AutomaticallyRegisteredFeatureProcessor.ANNOTATION_CLASS_NAME));
-            out.println("public final class " + featureClassName + " implements " +
-                            String.join(", ", new String[]{AutomaticallyRegisteredFeatureProcessor.FEATURE_INTERFACE_CLASS_NAME, FEATURE_SINGLETON_NAME, UNSAVED_SINGLETON_NAME}) + " {");
+            List<TypeElement> singletonSuperclasses = getSingletonSuperclasses(annotatedType);
+            String supertypes = singletonSuperclasses.isEmpty()
+                            ? " implements " + String.join(", ", new String[]{AutomaticallyRegisteredFeatureProcessor.FEATURE_INTERFACE_CLASS_NAME, FEATURE_SINGLETON_NAME, UNSAVED_SINGLETON_NAME})
+                            : " extends " + getPackage(singletonSuperclasses.get(0)).getQualifiedName().toString() + "." + getTypeNameWithEnclosingClasses(singletonSuperclasses.get(0), "Feature");
+            out.println("public class " + featureClassName + supertypes + " {");
             out.println("    @Override");
             out.println("    public void afterRegistration(AfterRegistrationAccess access) {");
 
             List<TypeMirror> onlyWithList = getAnnotationValueList(singletonAnnotation, "onlyWith", TypeMirror.class);
             if (!onlyWithList.isEmpty()) {
                 for (var onlyWith : onlyWithList) {
                     out.println("        if (!new " + onlyWith + "().getAsBoolean()) {");
+                    if (!singletonSuperclasses.isEmpty()) {
+                        out.println("            super.afterRegistration(access);");
+                    }
                     out.println("            return;");
                     out.println("        }");
                 }
             }
 
             List<TypeMirror> keysFromAnnotation = getAnnotationValueList(singletonAnnotation, "value", TypeMirror.class);
+            for (var superclass : singletonSuperclasses) {
+                AnnotationMirror superclassAnnotation = getAnnotation(superclass, getType(ANNOTATION_CLASS_NAME));
+                keysFromAnnotation.addAll(getAnnotationValueList(superclassAnnotation, "value", TypeMirror.class));
+            }
+
             if (keysFromAnnotation.isEmpty()) {
                 String keyname = "" + annotatedType + ".class";
                 out.println("        if (ImageSingletons.lookup(" + LAYERED_SINGLETON_INFO + ".class).handledDuringLoading(" + keyname + ")){");
@@ -130,6 +144,29 @@ private void processElement(TypeElement annotatedType) {
         }
     }
 
+    /**
+     * Get the inheritance chain from {@code annotatedType} up to (excluding) the first
+     * non-{@code @AutomaticallyRegisteredImageSingleton} type.
+     *
+     * @return a list ordered from the most specific to the least specific, empty if not even the
+     *         direct superclass is annotated
+     */
+    private List<TypeElement> getSingletonSuperclasses(TypeElement annotatedType) {
+        List<TypeElement> list = new ArrayList<>();
+        for (TypeElement curr = annotatedType;;) {
+            TypeMirror next = curr.getSuperclass();
+            if (next.getKind() != TypeKind.DECLARED) {
+                break;
+            }
+            curr = (TypeElement) ((DeclaredType) next).asElement();
+            if (getAnnotation(curr, getType(ANNOTATION_CLASS_NAME)) == null) {
+                break;
+            }
+            list.add(curr);
+        }
+        return list;
+    }
+
     /**
      * We allow inner classes to be annotated. To make the generated service name unique, we need to
      * concatenate the simple names of all outer classes.