8379007: [lworld] JNI NewWeakGlobalRef should throw IdentityException for value types

Reviewed-by: liach, heidinga

Author: David Holmes

src/hotspot/share/prims/jni.cpp

@@ -2944,7 +2944,16 @@ JNI_END
 
 JNI_ENTRY(jweak, jni_NewWeakGlobalRef(JNIEnv *env, jobject ref))
   HOTSPOT_JNI_NEWWEAKGLOBALREF_ENTRY(env, ref);
+
   Handle ref_handle(thread, JNIHandles::resolve(ref));
+
+  if (!ref_handle.is_null() && ref_handle->klass()->is_inline_klass()) {
+    ResourceMark rm(THREAD);
+    stringStream ss;
+    ss.print("%s is not an identity class", ref_handle->klass()->external_name());
+    THROW_MSG_(vmSymbols::java_lang_IdentityException(), ss.as_string(), nullptr);
+  }
+
   jweak ret = JNIHandles::make_weak_global(ref_handle, AllocFailStrategy::RETURN_NULL);
   if (ret == nullptr && ref_handle.not_null()) {
     THROW_OOP_(Universe::out_of_memory_error_c_heap(), nullptr);

test/hotspot/jtreg/runtime/valhalla/inlinetypes/TestJNINewWeakGlobalRef.java

@@ -0,0 +1,66 @@
+/*
+ * Copyright (c) 2026, 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.
+ *
+ * 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 runtime.valhalla.inlinetypes;
+
+import jdk.test.lib.Asserts;
+
+/*
+ * @test
+ * @summary Test JNI NewWeakGlobalRef with inline types
+ * @library /test/lib
+ * @enablePreview
+ * @run main/othervm/native --enable-native-access=ALL-UNNAMED
+ *                          runtime.valhalla.inlinetypes.TestJNINewWeakGlobalRef
+ */
+public class TestJNINewWeakGlobalRef {
+
+    static value class Value {
+        int i;
+
+        public Value(int i) {
+            this.i = i;
+        }
+    }
+
+    native static void newWeakGlobalRef(Object target);
+
+    static {
+        System.loadLibrary("JNINewWeakGlobalRef");
+    }
+
+    public static void main(String[] args) {
+        Value v = new Value(1);
+        try {
+            newWeakGlobalRef(v);
+            Asserts.fail("Should have thrown IdentityException");
+        }
+        catch (IdentityException i) {
+            Asserts.assertTrue(i.getMessage().contains("TestJNINewWeakGlobalRef$Value is not an identity class"),
+                               "Wrong identity exception: " + i);
+        }
+
+        // Sanity check that passing null doesn't cause an error.
+        newWeakGlobalRef(null);
+    }
+}

test/hotspot/jtreg/runtime/valhalla/inlinetypes/libJNINewWeakGlobalRef.c

@@ -0,0 +1,29 @@
+/*
+ * Copyright (c) 2026, 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.
+ *
+ * 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.
+ */
+
+#include <jni.h>
+
+JNIEXPORT void JNICALL
+Java_runtime_valhalla_inlinetypes_TestJNINewWeakGlobalRef_newWeakGlobalRef(JNIEnv* env, jclass klass, jobject target) {
+  (*env)->NewWeakGlobalRef(env, target);
+}