/*

 * Copyright (c) 2017, 2018, 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 TestMaybeNullUnsafeAccess

 * @summary cast before unsafe access moved in dominating null check null path causes crash

 * @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

 *                   TestMaybeNullUnsafeAccess

 *

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

 *                   -XX:+UnlockExperimentalVMOptions -XX:+UseShenandoahGC

 *                   TestMaybeNullUnsafeAccess

 *

 */

import jdk.internal.misc.Unsafe;

import java.lang.reflect.Field;

public class TestMaybeNullUnsafeAccess {

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

    static final long F_OFFSET;

    static class A {

        int f;

    }

    static {

        try {

            Field fField = A.class.getDeclaredField("f");

            F_OFFSET = UNSAFE.objectFieldOffset(fField);

        } catch (Exception e) {

            throw new RuntimeException(e);

        }

    }

    static A test_helper(Object o) {

        return (A) o;

    }

    static int test(Object o) {

        int f = 0;

        for (int i = 0; i < 100; i++) {

            A a = test_helper(o);

            f = UNSAFE.getInt(a, F_OFFSET);

        }

        return f;

    }

    static public void main(String[] args) {

        A a = new A();

        for (int i = 0; i < 20000; i++) {

            test_helper(null);

            test_helper(a);

            test(a);

        }

    }

}