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  * @summary tests on constant folding of unsafe get operations
  29  * @library /testlibrary /test/lib
  30  *
  31  * @run main/bootclasspath -XX:+UnlockDiagnosticVMOptions
  32  *                   -Xbatch -XX:-TieredCompilation
  33  *                   -XX:+FoldStableValues
  34  *                   UnsafeGetStableArrayElement
  35  *
  36  * @run main/bootclasspath -XX:+UnlockDiagnosticVMOptions
  37  *                   -Xbatch -XX:+TieredCompilation -XX:TieredStopAtLevel=1
  38  *                   -XX:+FoldStableValues
  39  *                   UnsafeGetStableArrayElement
  40  */
  41 import jdk.internal.misc.Unsafe;
  42 import jdk.internal.vm.annotation.Stable;
  43 import java.util.concurrent.Callable;
  44 
  45 import static jdk.internal.misc.Unsafe.*;
  46 import static jdk.test.lib.Asserts.*;
  47 
  48 public class UnsafeGetStableArrayElement {
  49     @Stable static final byte[] STABLE_BYTE_ARRAY = new byte[] { 0, 1, -128, 127};
  50 
  51     static final Unsafe U = Unsafe.getUnsafe();
  52 
  53     static int testChar() {
  54         return U.getChar(STABLE_BYTE_ARRAY, ARRAY_BYTE_BASE_OFFSET + 0 * ARRAY_CHAR_INDEX_SCALE) +
  55                U.getChar(STABLE_BYTE_ARRAY, ARRAY_BYTE_BASE_OFFSET + 1 * ARRAY_CHAR_INDEX_SCALE);
  56     }
  57 
  58     static void run(Callable c) throws Exception {
  59         Object first = c.call();
  60         for (int i = 0; i < 20_000; i++) {
  61             assertEQ(first, c.call());
  62         }
  63     }
  64 
  65     public static void main(String[] args) throws Exception {
  66         run(UnsafeGetStableArrayElement::testChar);
  67     }
  68 }