--- old/src/hotspot/share/classfile/fieldLayoutBuilder.cpp	2019-11-22 16:13:25.000000000 -0500
+++ new/src/hotspot/share/classfile/fieldLayoutBuilder.cpp	2019-11-22 16:13:24.000000000 -0500
@@ -561,8 +561,10 @@
                 _cfp->_protection_domain, true, CHECK);
         assert(klass != NULL, "Sanity check");
         ValueKlass* vk = ValueKlass::cast(klass);
-        bool flattened = (ValueFieldMaxFlatSize < 0)
+        bool has_flattenable_size = (ValueFieldMaxFlatSize < 0)
                          || (vk->size_helper() * HeapWordSize) <= ValueFieldMaxFlatSize;
+        // volatile fields are currently never flattened, this could change in the future
+        bool flattened = !fs.access_flags().is_volatile() && has_flattenable_size;
         if (flattened) {
           group->add_flattened_field(fs, vk);
           _nonstatic_oopmap_count += vk->nonstatic_oop_map_count();
--- /dev/null	2019-11-22 16:13:26.000000000 -0500
+++ new/test/hotspot/jtreg/runtime/valhalla/valuetypes/VolatileTest.java	2019-11-22 16:13:25.000000000 -0500
@@ -0,0 +1,66 @@
+/*
+ * Copyright (c) 2019, 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.
+ */
+
+package runtime.valhalla.valuetypes;
+
+/*
+ * @test VolatileTest
+ * @summary check effect of volatile keyword on flattenable fields
+ * @modules java.base/jdk.internal.misc
+ * @library /test/lib
+ * @run main/othervm runtime.valhalla.valuetypes.VolatileTest
+ */
+
+import jdk.internal.misc.Unsafe;
+
+import java.lang.reflect.*;
+import jdk.test.lib.Asserts;
+
+public class VolatileTest {
+    static final Unsafe U = Unsafe.getUnsafe();
+
+    static inline class MyValue {
+	int i = 0;
+	int j = 0;
+    }
+
+    static class MyContainer {
+	MyValue mv0;
+	volatile MyValue mv1;
+    }
+
+    static public void main (String[] args) {
+	Class<?> c = MyContainer.class;
+	Field f0 = null;
+	Field f1 = null;
+	try {
+	    f0 = c.getDeclaredField("mv0");
+	    f1 = c.getDeclaredField("mv1");
+	} catch(NoSuchFieldException e) {
+	    e.printStackTrace();
+	    return;
+	}
+	Asserts.assertTrue(U.isFlattened(f0), "mv0 should be flattened");
+	Asserts.assertFalse(U.isFlattened(f1), "mv1 should not be flattened");
+    }
+}