Implement sealed class support

Author: lazar-mitrovic

compiler/src/org.graalvm.compiler.core.common/src/org/graalvm/compiler/core/common/NumUtil.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2011, 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2011, 2021, 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
@@ -105,6 +105,11 @@ public static boolean is32bit(long x) {
         return -0x80000000L <= x && x < 0x80000000L;
     }
 
+    public static byte safeToUByte(int v) {
+        assert isUByte(v);
+        return (byte) v;
+    }
+
     public static byte safeToByte(int v) {
         assert isByte(v);
         return (byte) v;

substratevm/src/com.oracle.svm.core.jdk17/src/com/oracle/svm/core/jdk17/SealedClassSupportJDK17OrLater.java

@@ -0,0 +1,54 @@
+/*
+ * Copyright (c) 2021, 2021, 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
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+package com.oracle.svm.core.jdk17;
+
+// Checkstyle: allow reflection
+
+import com.oracle.svm.core.annotate.AutomaticFeature;
+import com.oracle.svm.core.jdk.SealedClassSupport;
+import org.graalvm.compiler.serviceprovider.JavaVersionUtil;
+import org.graalvm.nativeimage.ImageSingletons;
+import org.graalvm.nativeimage.hosted.Feature;
+
+final class SealedClassSupportJDK17OrLater extends SealedClassSupport {
+
+    @Override
+    public Class<?>[] getPermittedSubclasses(Class<?> clazz) {
+        return clazz.getPermittedSubclasses();
+    }
+}
+
+@AutomaticFeature
+final class SealedClassFeatureJDK17OrLater implements Feature {
+    @Override
+    public boolean isInConfiguration(IsInConfigurationAccess access) {
+        return JavaVersionUtil.JAVA_SPEC >= 17;
+    }
+
+    @Override
+    public void afterRegistration(AfterRegistrationAccess access) {
+        ImageSingletons.add(SealedClassSupport.class, new SealedClassSupportJDK17OrLater());
+    }
+}

substratevm/src/com.oracle.svm.core/src/com/oracle/svm/core/hub/DynamicHub.java

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2012, 2020, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2012, 2021, 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
@@ -276,6 +276,12 @@ public final class DynamicHub implements JavaKind.FormatWithToString, AnnotatedE
      */
     private Object annotationsEncoding;
 
+    /**
+     * Permitted subclasses for this class. This value is created during the image build by caching
+     * Class.getPermittedSubclasses() value for usage in {@link DynamicHub#getPermittedSubclasses()}
+     */
+    private Class<?>[] permittedSubclasses;
+
     /**
      * Metadata for running class initializers at run time. Refers to a singleton marker object for
      * classes/interfaces already initialized during image generation, i.e., this field is never
@@ -359,7 +365,7 @@ public DynamicHub(Class<?> hostedJavaClass, String name, HubType hubType, Refere
         this.classLoader = PredefinedClassesSupport.isPredefined(hostedJavaClass) ? NO_CLASS_LOADER : classLoader;
         this.nestHost = nestHost;
 
-        this.flags = NumUtil.safeToByte(makeFlag(IS_PRIMITIVE_FLAG_BIT, hostedJavaClass.isPrimitive()) |
+        this.flags = NumUtil.safeToUByte(makeFlag(IS_PRIMITIVE_FLAG_BIT, hostedJavaClass.isPrimitive()) |
                         makeFlag(IS_INTERFACE_FLAG_BIT, hostedJavaClass.isInterface()) |
                         makeFlag(IS_HIDDED_FLAG_BIT, isHidden) |
                         makeFlag(IS_RECORD_FLAG_BIT, isRecord) |
@@ -459,6 +465,11 @@ public Object getAnnotationsEncoding() {
         return annotationsEncoding;
     }
 
+    @Platforms(Platform.HOSTED_ONLY.class)
+    public void setPermittedSubclasses(Class<?>[] permittedSubclasses) {
+        this.permittedSubclasses = permittedSubclasses;
+    }
+
     @Platforms(Platform.HOSTED_ONLY.class)
     public boolean shouldInitEnumConstants() {
         return enumConstantsReference == null;
@@ -804,6 +815,10 @@ public boolean isRecord() {
         return isFlagSet(IS_RECORD_FLAG_BIT);
     }
 
+    @KeepOriginal
+    @TargetElement(onlyWith = JDK17OrLater.class)
+    public native boolean isSealed();
+
     @Substitute
     private boolean isLocalClass() {
         return booleanOrError(isLocalClass);
@@ -1216,6 +1231,14 @@ private Target_java_lang_reflect_RecordComponent[] getRecordComponents0() {
         return (Target_java_lang_reflect_RecordComponent[]) result;
     }
 
+    @Substitute
+    @TargetElement(onlyWith = JDK17OrLater.class)
+    private Class<?>[] getPermittedSubclasses() {
+        /* Original implementation depends on several private methods that aren't
+        * needed here, since we are only returning the cached value. */
+        return permittedSubclasses;
+    }
+
     @Substitute
     @TargetElement(name = "checkMemberAccess", onlyWith = JDK8OrEarlier.class)
     @SuppressWarnings("unused")

substratevm/src/com.oracle.svm.core/src/com/oracle/svm/core/jdk/SealedClassSupport.java

@@ -0,0 +1,74 @@
+/*
+ * Copyright (c) 2021, 2021, 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
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.  Oracle designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Oracle in the LICENSE file that accompanied this code.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+package com.oracle.svm.core.jdk;
+
+// Checkstyle: allow reflection
+
+import com.oracle.svm.core.annotate.AutomaticFeature;
+import org.graalvm.compiler.serviceprovider.JavaVersionUtil;
+import org.graalvm.nativeimage.ImageSingletons;
+import org.graalvm.nativeimage.Platform;
+import org.graalvm.nativeimage.Platforms;
+import org.graalvm.nativeimage.hosted.Feature;
+
+/**
+ * Abstracts the information about sealed classes, which are not available in Java 11 and Java 8.
+ * This class provides all information about sealed classes without exposing any JDK types and
+ * methods that are not yet present in the old JDKs.
+ */
+@Platforms(Platform.HOSTED_ONLY.class)
+public abstract class SealedClassSupport {
+
+    public static SealedClassSupport singleton() {
+        return ImageSingletons.lookup(SealedClassSupport.class);
+    }
+
+    /** Same as {@code Class.permittedSubclasses()}. */
+    public abstract Class<?>[] getPermittedSubclasses(Class<?> clazz);
+}
+
+/**
+ * Placeholder implementation for JDK versions that do not have sealed classes.
+ */
+final class SealedClassSupportJDK11OrEarlier extends SealedClassSupport {
+
+    @Override
+    public Class<?>[] getPermittedSubclasses(Class<?> clazz) {
+        return null;
+    }
+}
+
+@AutomaticFeature
+final class SealedClassFeatureBeforeJDK17 implements Feature {
+    @Override
+    public boolean isInConfiguration(IsInConfigurationAccess access) {
+        return JavaVersionUtil.JAVA_SPEC <= 11;
+    }
+
+    @Override
+    public void afterRegistration(AfterRegistrationAccess access) {
+        ImageSingletons.add(SealedClassSupport.class, new SealedClassSupportJDK11OrEarlier());
+    }
+}

substratevm/src/com.oracle.svm.hosted/src/com/oracle/svm/hosted/analysis/DynamicHubInitializer.java

@@ -43,6 +43,7 @@
 import com.oracle.svm.core.hub.AnnotatedSuperInfo;
 import com.oracle.svm.core.hub.DynamicHub;
 import com.oracle.svm.core.hub.GenericInfo;
+import com.oracle.svm.core.jdk.SealedClassSupport;
 import com.oracle.svm.core.meta.SubstrateObjectConstant;
 import com.oracle.svm.hosted.SVMHost;
 
@@ -103,6 +104,11 @@ public void initializeMetaData(AnalysisType type) {
                 fillInterfaces(type, hub);
             }
 
+            /*
+             * Support for permitted subclasses of a sealed class.
+             */
+            hub.setPermittedSubclasses(SealedClassSupport.singleton().getPermittedSubclasses(type.getJavaClass()));
+
             /*
              * Support for Java annotations.
              */