test/hotspot/jtreg/compiler/unsafe/TestMisalignedUnsafeAccess.java

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/**
 * @test
 * @bug 8250825
 * @summary "assert(field != __null) failed: missing field" in TypeOopPtr::TypeOopPt(...) with misaligned unsafe accesses
 * @library /test/lib
 * @modules java.base/jdk.internal.misc
 * @run main/othervm -XX:-TieredCompilation -Xcomp
 *                   -XX:CompileCommand=compileonly,TestMisalignedUnsafeAccess::test* TestMisalignedUnsafeAccess
 */

import java.lang.reflect.Field;
import jdk.internal.misc.Unsafe;
import jdk.test.lib.Asserts;

public class TestMisalignedUnsafeAccess {

    private static final Unsafe UNSAFE = Unsafe.getUnsafe();;

    private static short onHeapStaticMemory; // For static field testing
    private static final Object onHeapStaticMemoryBase;
    private static final long onHeapStaticMemoryOffset;

    private short onHeapInstanceMemory; // For instance field testing
    private static final long onHeapInstanceMemoryOffset;

    static {
        try {
            Field staticField = TestMisalignedUnsafeAccess.class.getDeclaredField("onHeapStaticMemory");
            onHeapStaticMemoryBase = UNSAFE.staticFieldBase(staticField);
            onHeapStaticMemoryOffset = UNSAFE.staticFieldOffset(staticField);

            Field instanceField = TestMisalignedUnsafeAccess.class.getDeclaredField("onHeapInstanceMemory");
            onHeapInstanceMemoryOffset = UNSAFE.objectFieldOffset(instanceField);
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }

    public static void testStaticField() {
        byte b1 = 0x01;
        byte b2 = 0x02;

        UNSAFE.putByte(onHeapStaticMemoryBase, onHeapStaticMemoryOffset, b1);
        UNSAFE.putByte(onHeapStaticMemoryBase, onHeapStaticMemoryOffset + 1, b2);

        Asserts.assertEquals(b1, UNSAFE.getByte(onHeapStaticMemoryBase, onHeapStaticMemoryOffset));
        Asserts.assertEquals(b2, UNSAFE.getByte(onHeapStaticMemoryBase, onHeapStaticMemoryOffset + 1));
    }

    public static void testInstanceField() {
        byte b1 = 0x03;
        byte b2 = 0x04;
        TestMisalignedUnsafeAccess obj = new TestMisalignedUnsafeAccess();

        UNSAFE.putByte(obj, onHeapInstanceMemoryOffset, b1);
        UNSAFE.putByte(obj, onHeapInstanceMemoryOffset + 1, b2);

        Asserts.assertEquals(b1, UNSAFE.getByte(obj, onHeapInstanceMemoryOffset));
        Asserts.assertEquals(b2, UNSAFE.getByte(obj, onHeapInstanceMemoryOffset + 1));
    }

    public static void main(String[] args) {
        testStaticField();
        testInstanceField();
    }
}