--- /dev/null 2017-02-26 20:56:26.359175879 +0100 +++ new/test/compiler/c1/UnsafeVolatileGuardTest.java 2017-03-03 18:45:45.734629538 +0100 @@ -0,0 +1,72 @@ +/* + * Copyright (c) 2017, Red Hat Inc. 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.reflect.Field; + +/** + * @test + * @bug 8175887 + * @summary C1 value numbering handling of Unsafe.get*Volatile is incorrect + * @run main/othervm -XX:+IgnoreUnrecognizedVMOptions -XX:TieredStopAtLevel=1 UnsafeVolatileGuardTest + */ +public class UnsafeVolatileGuardTest { + volatile static private int a; + static private int b; + + static final sun.misc.Unsafe UNSAFE; + + static final Object BASE; + static final long OFFSET; + + static { + try { + Field uf = sun.misc.Unsafe.class.getDeclaredField("theUnsafe"); + uf.setAccessible(true); + UNSAFE = (sun.misc.Unsafe)uf.get(null); + + Field f = UnsafeVolatileGuardTest.class.getDeclaredField("a"); + BASE = UNSAFE.staticFieldBase(f); + OFFSET = UNSAFE.staticFieldOffset(f); + } catch (Exception e) { + throw new RuntimeException(e); + } + } + + static void test() { + int tt = b; // makes the JVM CSE the value of b + + while (UNSAFE.getIntVolatile(BASE, OFFSET) == 0) {} // burn + if (b == 0) { + System.err.println("wrong value of b"); + System.exit(1); // fail hard to report the error + } + } + + public static void main(String [] args) throws Exception { + for (int i = 0; i < 10; i++) { + new Thread(UnsafeVolatileGuardTest::test).start(); + } + b = 1; + a = 1; + } +}