/*

 * Copyright (c) 2019, 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.

 *

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/**

 * @test TestUnsafeOffheapSwap

 * @summary Miscompilation in Unsafe off-heap swap routines

 * @key gc

 * @requires vm.gc.Shenandoah & !vm.graal.enabled

 * @modules java.base/jdk.internal.misc:+open

 *

 * @run main/othervm -XX:-UseOnStackReplacement -XX:-BackgroundCompilation -XX:-TieredCompilation

 *                   -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC

 *                   TestUnsafeOffheapSwap

 */

import java.util.*;

import jdk.internal.misc.Unsafe;

public class TestUnsafeOffheapSwap {

    static final int SIZE = 10000;

    static final long SEED = 1;

    static final jdk.internal.misc.Unsafe UNSAFE = Unsafe.getUnsafe();

    static final int SCALE = UNSAFE.ARRAY_INT_INDEX_SCALE;

    static Memory mem;

    static int[] arr;

    public static void main(String[] args) throws Exception {

        // Bug is exposed when memory.addr is not known statically

        mem = new Memory(SIZE*SCALE);

        arr = new int[SIZE];

        for (int i = 0; i < 10; i++) {

            test();

        }

    }

    static void test() {

        Random rnd = new Random(SEED);

        for (int i = 0; i < SIZE; i++) {

            int value = rnd.nextInt();

            mem.setInt(i, value);

            arr[i] = value;

        }

        for (int i = 0; i < SIZE; i++) {

            if (arr[i] != mem.getInt(i)) {

                throw new IllegalStateException("TESTBUG: Values mismatch before swaps");

            }

        }

        for (int i = 1; i < SIZE; i++) {

            mem.swap(i - 1, i);

            int tmp = arr[i - 1];

            arr[i - 1] = arr[i];

            arr[i] = tmp;

        }

        for (int i = 0; i < SIZE; i++) {

            if (arr[i] != mem.getInt(i)) {

                throw new IllegalStateException("Values mismatch after swaps");

            }

        }

    }

    static class Memory {

        private final long addr;

        Memory(int size) {

            addr = UNSAFE.allocateMemory(size);

        }

        public int getInt(int idx) {

            return UNSAFE.getInt(addr + idx*SCALE);

        }

        public void setInt(int idx, int val) {

            UNSAFE.putInt(addr + idx*SCALE, val);

        }

        public void swap(int a, int b) {

            int tmp = getInt(a);

            setInt(a, getInt(b));

            setInt(b, tmp);

        }

    }

}