[GR-52917] Correctness problem when System.arraycopy a byte array

[liyuheng55555]

Steps to reproduce the issue
Run the code below with GraalVm to reproceduce the problem.

import java.nio.ByteBuffer;
import java.util.Arrays;

public class GraalVM {
    public static void main(String[] args) {
        for (int j = 0; j < 10000000; j++) {
            byte[] array1 = ByteBuffer.allocate(8).putLong(0).array();
            byte[] array2 = new byte[6];
            System.arraycopy(array1, 2, array2, 0, array1.length - 2);
            if (!Arrays.toString(array2).equals("[0, 0, 0, 0, 0, 0]")) {
                System.out.println(j);
                System.out.println(Arrays.toString(array1));
                System.out.println(Arrays.toString(array2));
            }
        }
    }
}

If everything goes right, the program won't print anything. Actually it will print something like:

2283065
[0, 0, 0, 0, 0, 0, 0, 0]
[61, -38, -82, -31, 0, 0]
2283066
[0, 0, 0, 0, 0, 0, 0, 0]
[1, 0, 0, 0, 0, 0]
2283067
[0, 0, 0, 0, 0, 0, 0, 0]
[-67, -38, -82, -31, 0, 0]

Describe GraalVM and your environment:

• java version "21.0.1" 2023-10-17
• Java(TM) SE Runtime Environment Oracle GraalVM 21.0.1+12.1 (build 21.0.1+12-jvmci-23.1-b19)
• Java HotSpot(TM) 64-Bit Server VM Oracle GraalVM 21.0.1+12.1 (build 21.0.1+12-jvmci-23.1-b19, mixed mode, sharing)

Also meet this problem in mac(arm verion) + GraalVM 17.0.10

[fniephaus]

Thanks for raising this and the concise reproducer. We'll look into it!

[davleopo]

@liyuheng55555 thanks for the nice reproducer. This was fixed by 2bb5ad0 - I also ensured the fix will be present in the upcoming April CPU releases of GraalVM.