[GR-70158] JVMCI: add ResolvedJavaType#isHidden

src/jdk.internal.vm.ci/share/classes/jdk/vm/ci/hotspot/HotSpotResolvedObjectTypeImpl.java

@@ -185,6 +185,11 @@ public ResolvedJavaType getComponentType() {
         return this.equals(componentType) ? null : componentType;
     }
 
+    @Override
+    public boolean isHidden() {
+        return (getMiscFlags() & config().jvmAccIsHiddenClass) != 0;
+    }
+
     @Override
     public List<JavaType> getPermittedSubclasses() {
         if (isArray() || isPrimitive()) {

src/jdk.internal.vm.ci/share/classes/jdk/vm/ci/hotspot/HotSpotResolvedPrimitiveType.java

@@ -102,6 +102,11 @@ public ResolvedJavaType getElementalType() {
         return this;
     }
 
+    @Override
+    public boolean isHidden() {
+        return false;
+    }
+
     @Override
     public List<JavaType> getPermittedSubclasses() {
         return null;

src/jdk.internal.vm.ci/share/classes/jdk/vm/ci/hotspot/HotSpotVMConfig.java

@@ -116,6 +116,7 @@ static String getHostArchitectureName() {
     final int arrayJUShortDataOffset = getFieldOffset("Array<jushort>::_data", Integer.class);
     final int arrayJUShortLengthOffset = getFieldOffset("Array<jushort>::_length", Integer.class, "int");
 
+    final int jvmAccIsHiddenClass = getConstant("KlassFlags::_misc_is_hidden_class", Integer.class);
     final int jvmAccHasFinalizer = getConstant("KlassFlags::_misc_has_finalizer", Integer.class);
     final int jvmFieldFlagInternalShift = getConstant("FieldInfo::FieldFlags::_ff_injected", Integer.class);
     final int jvmFieldFlagStableShift = getConstant("FieldInfo::FieldFlags::_ff_stable", Integer.class);

src/jdk.internal.vm.ci/share/classes/jdk/vm/ci/meta/ResolvedJavaType.java

@@ -247,6 +247,15 @@ default ResolvedJavaType getElementalType() {
     @Override
     ResolvedJavaType getArrayClass();
 
+    /**
+     * Returns {@code true} if and only if the underlying class is a hidden class.
+     *
+     * @return {@code true} if and only if this class is a hidden class
+     *
+     * @see Class#isHidden()
+     */
+    boolean isHidden();
+
     /**
      * Returns an unmodifiable list of {@link JavaType} objects representing the subclasses or
      * subinterfaces that are explicitly permitted to extend or implement this sealed class or

test/hotspot/jtreg/compiler/jvmci/jdk.vm.ci.runtime.test/src/jdk/vm/ci/runtime/test/TestResolvedJavaType.java

@@ -61,10 +61,12 @@
 import static org.junit.Assert.assertTrue;
 import static org.junit.Assert.fail;
 
+import java.io.ByteArrayOutputStream;
 import java.io.DataInputStream;
 import java.io.IOException;
 import java.io.InputStream;
 import java.lang.annotation.Annotation;
+import java.lang.invoke.MethodHandles;
 import java.lang.invoke.MethodHandles.Lookup;
 import java.lang.reflect.AccessibleObject;
 import java.lang.reflect.AnnotatedElement;
@@ -709,6 +711,36 @@ public void getArrayClassTest() {
         }
     }
 
+    static class HiddenPrototype {}
+
+    @Test
+    public void isHiddenTest() throws IllegalAccessException {
+        // non-hidden class
+        assertFalse(TestResolvedJavaType.class.isHidden());
+        assertFalse(metaAccess.lookupJavaType(TestResolvedJavaType.class).isHidden());
+        // hidden class
+        Lookup lookup = MethodHandles.lookup();
+        byte[] bytes = getClassBytes(HiddenPrototype.class);
+        Class<?> c = lookup.defineHiddenClass(bytes, true).lookupClass();
+        assertTrue(c.isHidden());
+        assertTrue(metaAccess.lookupJavaType(c).isHidden());
+    }
+
+    static byte[] getClassBytes(Class<?> originalClass) {
+        try (InputStream classFile = originalClass.getResourceAsStream("TestResolvedJavaType$HiddenPrototype.class")) {
+            ByteArrayOutputStream buffer = new ByteArrayOutputStream();
+            int nRead;
+            byte[] data = new byte[16384];
+
+            while ((nRead = classFile.read(data, 0, data.length)) != -1) {
+                buffer.write(data, 0, nRead);
+            }
+            return buffer.toByteArray();
+        } catch (IOException e) {
+            throw new AssertionError(e);
+        }
+    }
+
     private static sealed class SealedTestClass
       permits PermittedTestClass1, PermittedTestClass3 {
     }