--- old/src/java.base/share/classes/java/lang/ref/PhantomReference.java	2019-05-23 15:39:18.441433248 -0400
+++ new/src/java.base/share/classes/java/lang/ref/PhantomReference.java	2019-05-23 15:39:18.045431284 -0400
@@ -30,6 +30,9 @@
  * Phantom reference objects, which are enqueued after the collector
  * determines that their referents may otherwise be reclaimed.  Phantom
  * references are most often used to schedule post-mortem cleanup actions.
+ * <p>
+ * The referent must not be an instance of an inline class; such a value
+ * can never have another reference to it and cannot be held in a reference type.
  *
  * <p> Suppose the garbage collector determines at a certain point in time
  * that an object is <a href="package-summary.html#reachability">
@@ -72,6 +75,8 @@
      * @param referent the object the new phantom reference will refer to
      * @param q the queue with which the reference is to be registered,
      *          or {@code null} if registration is not required
+     * @throws IllegalArgumentException if the referent is an instance of an
+     *         {@link Class#isInlineClass() inlineClass}
      */
     public PhantomReference(T referent, ReferenceQueue<? super T> q) {
         super(referent, q);
--- old/src/java.base/share/classes/java/lang/ref/Reference.java	2019-05-23 15:39:19.657439278 -0400
+++ new/src/java.base/share/classes/java/lang/ref/Reference.java	2019-05-23 15:39:19.257437294 -0400
@@ -396,6 +396,10 @@
     }
 
     Reference(T referent, ReferenceQueue<? super T> queue) {
+        if (referent != null && referent.getClass().isInlineClass()) {
+            throw new IllegalArgumentException("cannot reference an inline value of type: " +
+                    referent.getClass().getName());
+        }
         this.referent = referent;
         this.queue = (queue == null) ? ReferenceQueue.NULL : queue;
     }
--- old/src/java.base/share/classes/java/lang/ref/SoftReference.java	2019-05-23 15:39:20.833445109 -0400
+++ new/src/java.base/share/classes/java/lang/ref/SoftReference.java	2019-05-23 15:39:20.441443165 -0400
@@ -30,6 +30,9 @@
  * Soft reference objects, which are cleared at the discretion of the garbage
  * collector in response to memory demand.  Soft references are most often used
  * to implement memory-sensitive caches.
+ * <p>
+ * The referent must not be an instance of an inline class; such a value
+ * can never have another reference to it and cannot be held in a reference type.
  *
  * <p> Suppose that the garbage collector determines at a certain point in time
  * that an object is <a href="package-summary.html#reachability">softly
@@ -80,6 +83,8 @@
      * reference is not registered with any queue.
      *
      * @param referent object the new soft reference will refer to
+     * @throws IllegalArgumentException if the referent is an instance of an
+     *         {@link Class#isInlineClass() inlineClass}
      */
     public SoftReference(T referent) {
         super(referent);
@@ -93,7 +98,8 @@
      * @param referent object the new soft reference will refer to
      * @param q the queue with which the reference is to be registered,
      *          or {@code null} if registration is not required
-     *
+     * @throws IllegalArgumentException if the referent is an instance of an
+     *         {@link Class#isInlineClass() inlineClass}
      */
     public SoftReference(T referent, ReferenceQueue<? super T> q) {
         super(referent, q);
--- old/src/java.base/share/classes/java/lang/ref/WeakReference.java	2019-05-23 15:39:21.961450703 -0400
+++ new/src/java.base/share/classes/java/lang/ref/WeakReference.java	2019-05-23 15:39:21.573448779 -0400
@@ -30,6 +30,9 @@
  * Weak reference objects, which do not prevent their referents from being
  * made finalizable, finalized, and then reclaimed.  Weak references are most
  * often used to implement canonicalizing mappings.
+ * <p>
+ * The referent must not be an instance of an inline class; such a value
+ * can never have another reference to it and cannot be held in a reference type.
  *
  * <p> Suppose that the garbage collector determines at a certain point in time
  * that an object is <a href="package-summary.html#reachability">weakly
@@ -52,6 +55,8 @@
      * reference is not registered with any queue.
      *
      * @param referent object the new weak reference will refer to
+     * @throws IllegalArgumentException if the referent is an instance of an
+     *         {@link Class#isInlineClass() inlineClass}
      */
     public WeakReference(T referent) {
         super(referent);
@@ -64,6 +69,8 @@
      * @param referent object the new weak reference will refer to
      * @param q the queue with which the reference is to be registered,
      *          or {@code null} if registration is not required
+     * @throws IllegalArgumentException if the referent is an instance of an
+     *         {@link Class#isInlineClass() inlineClass}
      */
     public WeakReference(T referent, ReferenceQueue<? super T> q) {
         super(referent, q);
--- old/test/jdk/valhalla/valuetypes/Point.java	2019-05-23 15:39:23.001455860 -0400
+++ new/test/jdk/valhalla/valuetypes/Point.java	2019-05-23 15:39:22.609453916 -0400
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2017, 2019, 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
@@ -35,4 +35,9 @@
         p = __WithField(p.y, y);
         return p;
     }
+
+    public Point(int x, int y) {
+        this.x = x;
+        this.y = y;
+    }
 }
--- /dev/null	2019-05-01 12:58:11.532074540 -0400
+++ new/test/jdk/valhalla/valuetypes/InlineReferenceTest.java	2019-05-23 15:39:23.641459033 -0400
@@ -0,0 +1,53 @@
+/*
+ * Copyright (c) 2019, 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.
+ */
+
+import java.lang.ref.WeakReference;
+import java.lang.ref.ReferenceQueue;
+
+import org.testng.annotations.BeforeTest;
+import org.testng.annotations.DataProvider;
+import org.testng.annotations.Test;
+import static org.testng.Assert.*;
+
+/*
+ * @test
+ * @summary Test inline classes with Reference types
+ * @compile -XDallowWithFieldOperator Point.java
+ * @run testng/othervm -XX:+EnableValhalla InlineReferenceTest
+ */
+@Test
+public class InlineReferenceTest {
+
+    @Test(expectedExceptions = IllegalArgumentException.class)
+    static void test1() {
+        Point? p = new Point(10,20);
+        WeakReference<Point?> r = new WeakReference<>(p);
+    }
+
+    @Test(expectedExceptions = IllegalArgumentException.class)
+    static void test2() {
+        ReferenceQueue<Object> q = new ReferenceQueue<>();
+        Point? p = new Point(1,2);
+        WeakReference<Point?> r = new WeakReference<>(p, q);
+    }
+}