test/jdk/java/foreign/TestVarHandleCombinators.java

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/*
 * @test
 * @run testng TestVarHandleCombinators
 */

import java.lang.foreign.Arena;
import java.lang.foreign.ValueLayout;

import org.testng.annotations.Test;

import java.lang.foreign.MemorySegment;
import java.lang.invoke.MethodHandles;
import java.lang.invoke.VarHandle;
import java.nio.ByteOrder;

import static org.testng.Assert.assertEquals;

public class TestVarHandleCombinators {

    @Test
    public void testElementAccess() {
        VarHandle vh = ValueLayout.JAVA_BYTE.varHandle();

        byte[] arr = { 0, 0, -1, 0 };
        MemorySegment segment = MemorySegment.ofArray(arr);
        assertEquals((byte) vh.get(segment, 2), (byte) -1);
    }

    @Test(expectedExceptions = IllegalArgumentException.class)
    public void testUnalignedElement() {
        VarHandle vh = ValueLayout.JAVA_BYTE.withByteAlignment(4).varHandle();
        MemorySegment segment = MemorySegment.ofArray(new byte[4]);
        vh.get(segment, 2L); //should throw
        //FIXME: the VH only checks the alignment of the segment, which is fine if the VH is derived from layouts,
        //FIXME: but not if the VH is just created from scratch - we need a VH variable to govern this property,
        //FIXME: at least until the VM is fixed
    }

    @Test
    public void testAlign() {
        VarHandle vh = ValueLayout.JAVA_BYTE.withByteAlignment(2).varHandle();

        Arena scope = Arena.ofAuto();
        MemorySegment segment = scope.allocate(1L, 2);
        vh.set(segment, 0L, (byte) 10); // fine, memory region is aligned
        assertEquals((byte) vh.get(segment, 0L), (byte) 10);
    }

    @Test
    public void testByteOrderLE() {
        VarHandle vh = ValueLayout.JAVA_SHORT_UNALIGNED.withOrder(ByteOrder.LITTLE_ENDIAN).varHandle();
        byte[] arr = new byte[2];
        MemorySegment segment = MemorySegment.ofArray(arr);
        vh.set(segment, 0L, (short) 0xFF);
        assertEquals(arr[0], (byte) 0xFF);
        assertEquals(arr[1], (byte) 0);
    }

    @Test
    public void testByteOrderBE() {
        VarHandle vh = ValueLayout.JAVA_SHORT_UNALIGNED.withOrder(ByteOrder.BIG_ENDIAN).varHandle();
        byte[] arr = new byte[2];
        MemorySegment segment = MemorySegment.ofArray(arr);
        vh.set(segment, 0L, (short) 0xFF);
        assertEquals(arr[0], (byte) 0);
        assertEquals(arr[1], (byte) 0xFF);
    }

    @Test
    public void testNestedSequenceAccess() {
        int outer_size = 10;
        int inner_size = 5;

        //[10 : [5 : [x32 i32]]]

        VarHandle vh = ValueLayout.JAVA_INT.varHandle();
        int count = 0;
        try (Arena arena = Arena.ofConfined()) {
            MemorySegment segment = arena.allocate(inner_size * outer_size * 8, 4);
            for (long i = 0; i < outer_size; i++) {
                for (long j = 0; j < inner_size; j++) {
                    vh.set(segment, i * 40 + j * 8, count);
                    assertEquals(
                            (int)vh.get(segment.asSlice(i * inner_size * 8), j * 8),
                            count);
                    count++;
                }
            }
        }
    }
}