test/hotspot/jtreg/compiler/arraycopy/TestArrayCopyMaskedWithZeroSrc.java

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/*
 * @test
 * @bug 8258272
 * @summary Test that LoadVectorMaskedNodes works when the source array is known to only contain zeros
 *
 * @run main/othervm -XX:-BackgroundCompilation -XX:CompileCommand=dontinline,*::testArrayCopy*
 *                   compiler.arraycopy.TestArrayCopyMaskedWithZeroSrc
 */

package compiler.arraycopy;

import java.util.*;

public class TestArrayCopyMaskedWithZeroSrc {

    public static void main(String[] args) {
        TestArrayCopyMaskedWithZeroSrc t = new TestArrayCopyMaskedWithZeroSrc();
        t.test();
    }

    void test() {
        for (int i = 0; i < 20000; i++) {
            testArrayCopy1(3);
        }
    }

    // src is allocated locally - it is known it only contains zeros.
    // The copy of will exapnd into LoadVectorMasked on AVX512 machines
    // LoadNode::value will try to replace the load from src with a zero constant.

    byte [] testArrayCopy1(int partial_len) {
        byte [] src = new byte[5];
        byte [] dest = Arrays.copyOf(src, partial_len);
        return dest;
    }
}