dbuck@8879: /*
dbuck@8879:  * Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved.
dbuck@8879:  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
dbuck@8879:  *
dbuck@8879:  * This code is free software; you can redistribute it and/or modify it
dbuck@8879:  * under the terms of the GNU General Public License version 2 only, as
dbuck@8879:  * published by the Free Software Foundation.
dbuck@8879:  *
dbuck@8879:  * This code is distributed in the hope that it will be useful, but WITHOUT
dbuck@8879:  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
dbuck@8879:  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
dbuck@8879:  * version 2 for more details (a copy is included in the LICENSE file that
dbuck@8879:  * accompanied this code).
dbuck@8879:  *
dbuck@8879:  * You should have received a copy of the GNU General Public License version
dbuck@8879:  * 2 along with this work; if not, write to the Free Software Foundation,
dbuck@8879:  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
dbuck@8879:  *
dbuck@8879:  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
dbuck@8879:  * or visit www.oracle.com if you need additional information or have any
dbuck@8879:  * questions.
dbuck@8879:  */
dbuck@8879: 
dbuck@8879: /*
dbuck@8879:  * @test
dbuck@8879:  * @bug 8178047
dbuck@8879:  * @run main/othervm -XX:CompileCommand=exclude,*.main -XX:-TieredCompilation -XX:-BackgroundCompilation compiler.unsafe.TestRawAliasing
dbuck@8879:  */
dbuck@8879: 
dbuck@8879: package compiler.unsafe;
dbuck@8879: 
dbuck@8879: import java.lang.reflect.Field;
dbuck@8879: 
dbuck@8879: public class TestRawAliasing {
dbuck@8879:     static private final sun.misc.Unsafe UNSAFE;
dbuck@8879:     static {
dbuck@8879:         try {
dbuck@8879:             Field f = sun.misc.Unsafe.class.getDeclaredField("theUnsafe");
dbuck@8879:             f.setAccessible(true);
dbuck@8879:             UNSAFE = (sun.misc.Unsafe) f.get(null);
dbuck@8879:         } catch (Exception e) {
dbuck@8879:             throw new RuntimeException("Unable to get Unsafe instance.", e);
dbuck@8879:         }
dbuck@8879:     }
dbuck@8879: 
dbuck@8879:     static private final int OFFSET_X = 50;
dbuck@8879:     static private final int OFFSET_Y = 100;
dbuck@8879: 
dbuck@8879:     private static int test(long base_plus_offset_x, long base_plus_offset_y, int magic_value) {
dbuck@8879:         // write 0 to a location
dbuck@8879:         UNSAFE.putByte(base_plus_offset_x - OFFSET_X, (byte)0);
dbuck@8879:         // write unfoldable value to really the same location with another base
dbuck@8879:         UNSAFE.putByte(base_plus_offset_y - OFFSET_Y, (byte)magic_value);
dbuck@8879:         // read the value back, should be equal to "unfoldable_value"
dbuck@8879:         return UNSAFE.getByte(base_plus_offset_x - OFFSET_X);
dbuck@8879:     }
dbuck@8879: 
dbuck@8879:     private static final int OFF_HEAP_AREA_SIZE = 128;
dbuck@8879:     private static final byte MAGIC = 123;
dbuck@8879: 
dbuck@8879:     // main is excluded from compilation since we don't want the test method to inline and make base values fold
dbuck@8879:     public static void main(String... args) {
dbuck@8879:         long base = UNSAFE.allocateMemory(OFF_HEAP_AREA_SIZE);
dbuck@8879:         for (int i = 0; i < 100_000; i++) {
dbuck@8879:             if (test(base + OFFSET_X, base + OFFSET_Y, MAGIC) != MAGIC) {
dbuck@8879:                 throw new RuntimeException("Unexpected magic value");
dbuck@8879:             }
dbuck@8879:         }
dbuck@8879:     }
dbuck@8879: }