1 /*
   2  * Copyright (c) 2016, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.  Oracle designates this
   8  * particular file as subject to the "Classpath" exception as provided
   9  * by Oracle in the LICENSE file that accompanied this code.
  10  *
  11  * This code is distributed in the hope that it will be useful, but WITHOUT
  12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14  * version 2 for more details (a copy is included in the LICENSE file that
  15  * accompanied this code).
  16  *
  17  * You should have received a copy of the GNU General Public License version
  18  * 2 along with this work; if not, write to the Free Software Foundation,
  19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  20  *
  21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  22  * or visit www.oracle.com if you need additional information or have any
  23  * questions.
  24  */
  25 
  26 /*
  27  * @test
  28  * @bug 8155781
  29  * @modules java.base/jdk.internal.misc
  30  *
  31  * @run main/bootclasspath/othervm -XX:+IgnoreUnrecognizedVMOptions -XX:+UnlockDiagnosticVMOptions
  32  *                                 -XX:-TieredCompilation -Xbatch
  33  *                                 -XX:CompileCommand=dontinline,compiler.unsafe.OpaqueAccesses::test*
  34  *                                 compiler.unsafe.OpaqueAccesses
  35  */
  36 package compiler.unsafe;
  37 
  38 import jdk.internal.misc.Unsafe;
  39 
  40 import java.lang.reflect.Field;
  41 
  42 public class OpaqueAccesses {
  43     private static final Unsafe UNSAFE = Unsafe.getUnsafe();
  44 
  45     private static final Object INSTANCE = new OpaqueAccesses();
  46 
  47     private static final Object[] ARRAY = new Object[10];
  48 
  49     private static final long F_OFFSET;
  50     private static final long E_OFFSET;
  51 
  52     static {
  53         try {
  54             Field field = OpaqueAccesses.class.getDeclaredField("f");
  55             F_OFFSET = UNSAFE.objectFieldOffset(field);
  56 
  57             E_OFFSET = UNSAFE.arrayBaseOffset(ARRAY.getClass());
  58         } catch (NoSuchFieldException e) {
  59             throw new Error(e);
  60         }
  61     }
  62 
  63     private Object f = new Object();
  64 
  65     static Object testFixedOffsetField(Object o) {
  66         return UNSAFE.getObject(o, F_OFFSET);
  67     }
  68 
  69     static int testFixedOffsetHeader0(Object o) {
  70         return UNSAFE.getInt(o, 0);
  71     }
  72 
  73     static int testFixedOffsetHeader4(Object o) {
  74         return UNSAFE.getInt(o, 4);
  75     }
  76 
  77     static Object testFixedBase(long off) {
  78         return UNSAFE.getObject(INSTANCE, off);
  79     }
  80 
  81     static Object testOpaque(Object o, long off) {
  82         return UNSAFE.getObject(o, off);
  83     }
  84 
  85     static int testFixedOffsetHeaderArray0(Object[] arr) {
  86         return UNSAFE.getInt(arr, 0);
  87     }
  88 
  89     static int testFixedOffsetHeaderArray4(Object[] arr) {
  90         return UNSAFE.getInt(arr, 4);
  91     }
  92 
  93     static Object testFixedOffsetArray(Object[] arr) {
  94         return UNSAFE.getObject(arr, E_OFFSET);
  95     }
  96 
  97     static Object testFixedBaseArray(long off) {
  98         return UNSAFE.getObject(ARRAY, off);
  99     }
 100 
 101     static Object testOpaqueArray(Object[] o, long off) {
 102         return UNSAFE.getObject(o, off);
 103     }
 104 
 105     static final long ADDR = UNSAFE.allocateMemory(10);
 106     static boolean flag;
 107 
 108     static int testMixedAccess() {
 109         flag = !flag;
 110         Object o = (flag ? INSTANCE : null);
 111         long off = (flag ? F_OFFSET : ADDR);
 112         return UNSAFE.getInt(o, off);
 113     }
 114 
 115     public static void main(String[] args) {
 116         for (int i = 0; i < 20_000; i++) {
 117             // Instance
 118             testFixedOffsetField(INSTANCE);
 119             testFixedOffsetHeader0(INSTANCE);
 120             testFixedOffsetHeader4(INSTANCE);
 121             testFixedBase(F_OFFSET);
 122             testOpaque(INSTANCE, F_OFFSET);
 123             testMixedAccess();
 124 
 125             // Array
 126             testFixedOffsetHeaderArray0(ARRAY);
 127             testFixedOffsetHeaderArray4(ARRAY);
 128             testFixedOffsetArray(ARRAY);
 129             testFixedBaseArray(E_OFFSET);
 130             testOpaqueArray(ARRAY, E_OFFSET);
 131         }
 132         System.out.println("TEST PASSED");
 133     }
 134 }