test/hotspot/jtreg/gc/shenandoah/compiler/TestMaybeNullUnsafeAccess.java

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * version 2 for more details (a copy is included in the LICENSE file that
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 * 2 along with this work; if not, write to the Free Software Foundation,
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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
 * @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);
        }
    }

}