Implement sealed class support

Change flags field in DynamicHub to short

Author: lazar-mitrovic

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

@@ -0,0 +1,59 @@
+/*
+ * 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 boolean isSealed(Class<?> clazz) {
+        return clazz.isSealed();
+    }
+
+    @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
@@ -165,7 +165,7 @@ public final class DynamicHub implements JavaKind.FormatWithToString, AnnotatedE
      * field is final, so that various methods are constant folded for constant classes already
      * before the static analysis.
      */
-    private final byte flags;
+    private final short flags;
 
     /** Is this a primitive type. */
     private static final int IS_PRIMITIVE_FLAG_BIT = 0;
@@ -190,6 +190,11 @@ public final class DynamicHub implements JavaKind.FormatWithToString, AnnotatedE
      */
     private static final int DECLARES_DEFAULT_METHODS_FLAG_BIT = 6;
 
+    /**
+     * Is this a sealed Class.
+     */
+    private static final int IS_SEALED_FLAG_BIT = 7;
+
     /**
      * Has the type been discovered as instantiated by the static analysis?
      */
@@ -276,6 +281,12 @@ 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
@@ -344,7 +355,7 @@ public void setModule(Object module) {
 
     @Platforms(Platform.HOSTED_ONLY.class)
     public DynamicHub(Class<?> hostedJavaClass, String name, HubType hubType, ReferenceType referenceType, Object isLocalClass, Object isAnonymousClass, DynamicHub superType, DynamicHub componentHub,
-                    String sourceFileName, int modifiers, ClassLoader classLoader, boolean isHidden, boolean isRecord, Class<?> nestHost, boolean assertionStatus,
+                    String sourceFileName, int modifiers, ClassLoader classLoader, boolean isHidden, boolean isRecord,  boolean isSealed, Class<?> nestHost, boolean assertionStatus,
                     boolean hasDefaultMethods, boolean declaresDefaultMethods) {
         this.hostedJavaClass = hostedJavaClass;
         this.name = name;
@@ -359,13 +370,14 @@ 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.safeToShort(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) |
                         makeFlag(ASSERTION_STATUS_FLAG_BIT, assertionStatus) |
                         makeFlag(HAS_DEFAULT_METHODS_FLAG_BIT, hasDefaultMethods) |
-                        makeFlag(DECLARES_DEFAULT_METHODS_FLAG_BIT, declaresDefaultMethods));
+                        makeFlag(DECLARES_DEFAULT_METHODS_FLAG_BIT, declaresDefaultMethods) |
+                        makeFlag(IS_SEALED_FLAG_BIT, isSealed));
     }
 
     @Platforms(Platform.HOSTED_ONLY.class)
@@ -459,6 +471,11 @@ 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 +821,12 @@ public boolean isRecord() {
         return isFlagSet(IS_RECORD_FLAG_BIT);
     }
 
+    @Substitute
+    @TargetElement(onlyWith = JDK17OrLater.class)
+    public boolean isSealed() {
+        return isFlagSet(IS_SEALED_FLAG_BIT);
+    }
+
     @Substitute
     private boolean isLocalClass() {
         return booleanOrError(isLocalClass);
@@ -1216,6 +1239,12 @@ private Target_java_lang_reflect_RecordComponent[] getRecordComponents0() {
         return (Target_java_lang_reflect_RecordComponent[]) result;
     }
 
+    @Substitute
+    @TargetElement(onlyWith = JDK17OrLater.class)
+    private Class<?>[] getPermittedSubclasses() {
+        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 +1,81 @@
+/*
+ * 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.isSealed()}. */
+    public abstract boolean isSealed(Class<?> clazz);
+
+    /** 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 boolean isSealed(Class<?> clazz) {
+        return false;
+    }
+
+    @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/SVMHost.java

@@ -45,6 +45,7 @@
 import java.util.concurrent.CopyOnWriteArrayList;
 import java.util.function.BiConsumer;
 
+import com.oracle.svm.core.jdk.SealedClassSupport;
 import org.graalvm.compiler.core.common.spi.ForeignCallDescriptor;
 import org.graalvm.compiler.core.common.spi.ForeignCallsProvider;
 import org.graalvm.compiler.debug.MethodFilter;
@@ -402,11 +403,12 @@ private DynamicHub createHub(AnalysisType type) {
 
         boolean isHidden = SubstrateUtil.isHiddenClass(javaClass);
         boolean isRecord = RecordSupport.singleton().isRecord(javaClass);
+        boolean isSealed = SealedClassSupport.singleton().isSealed(javaClass);
         boolean assertionStatus = RuntimeAssertionsSupport.singleton().desiredAssertionStatus(javaClass);
 
         final DynamicHub dynamicHub = new DynamicHub(javaClass, className, computeHubType(type), computeReferenceType(type),
                         isLocalClass(javaClass), isAnonymousClass(javaClass), superHub, componentHub, sourceFileName,
-                        modifiers, hubClassLoader, isHidden, isRecord, nestHost, assertionStatus, type.hasDefaultMethods(), type.declaresDefaultMethods());
+                        modifiers, hubClassLoader, isHidden, isRecord, isSealed, nestHost, assertionStatus, type.hasDefaultMethods(), type.declaresDefaultMethods());
         if (JavaVersionUtil.JAVA_SPEC > 8) {
             ModuleAccess.extractAndSetModule(dynamicHub, javaClass);
         }

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.
              */