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/*
* Copyright (c) 2019, 2023, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
/*
* @test
* @enablePreview
* @run testng TestMemoryAlignment
*/
import java.lang.foreign.*;
import java.lang.foreign.MemoryLayout.PathElement;
import java.lang.invoke.VarHandle;
import java.nio.ByteOrder;
import java.util.stream.LongStream;
import org.testng.annotations.*;
import static org.testng.Assert.*;
public class TestMemoryAlignment {
@Test(dataProvider = "alignments")
public void testAlignedAccess(long align) {
ValueLayout layout = ValueLayout.JAVA_INT
.withOrder(ByteOrder.BIG_ENDIAN);
assertEquals(layout.byteAlignment(), 4);
ValueLayout aligned = layout.withByteAlignment(align);
assertEquals(aligned.byteAlignment(), align); //unreasonable alignment here, to make sure access throws
VarHandle vh = aligned.varHandle();
try (Arena arena = Arena.ofConfined()) {
MemorySegment segment = arena.allocate(aligned);;
vh.set(segment, -42);
int val = (int)vh.get(segment);
assertEquals(val, -42);
}
}
@Test(dataProvider = "alignments")
public void testUnalignedAccess(long align) {
ValueLayout layout = ValueLayout.JAVA_INT
.withOrder(ByteOrder.BIG_ENDIAN);
assertEquals(layout.byteAlignment(), 4);
ValueLayout aligned = layout.withByteAlignment(align);
try (Arena arena = Arena.ofConfined()) {
MemoryLayout alignedGroup = MemoryLayout.structLayout(MemoryLayout.paddingLayout(1), aligned);
assertEquals(alignedGroup.byteAlignment(), align);
VarHandle vh = aligned.varHandle();
MemorySegment segment = arena.allocate(alignedGroup);;
vh.set(segment.asSlice(1L), -42);
assertEquals(align, 8); //this is the only case where access is aligned
} catch (IllegalArgumentException ex) {
assertNotEquals(align, 8); //if align != 8, access is always unaligned
}
}
@Test(dataProvider = "alignments")
public void testUnalignedPath(long align) {
MemoryLayout layout = ValueLayout.JAVA_INT.withOrder(ByteOrder.BIG_ENDIAN);
MemoryLayout aligned = layout.withByteAlignment(align).withName("value");
try {
GroupLayout alignedGroup = MemoryLayout.structLayout(MemoryLayout.paddingLayout(1), aligned);
alignedGroup.varHandle(PathElement.groupElement("value"));
assertEquals(align, 1); //this is the only case where path is aligned
} catch (IllegalArgumentException ex) {
assertNotEquals(align, 1); //if align != 8, path is always unaligned
}
}
@Test(dataProvider = "alignments")
public void testUnalignedSequence(long align) {
try {
SequenceLayout layout = MemoryLayout.sequenceLayout(5, ValueLayout.JAVA_INT.withOrder(ByteOrder.BIG_ENDIAN).withByteAlignment(align));
VarHandle vh = layout.varHandle(PathElement.sequenceElement());
try (Arena arena = Arena.ofConfined()) {
MemorySegment segment = arena.allocate(layout);;
for (long i = 0 ; i < 5 ; i++) {
vh.set(segment, i, -42);
}
}
} catch (IllegalArgumentException ex) {
assertTrue(align > 4); //if align > 4, access is always unaligned (for some elements)
}
}
@Test
public void testPackedAccess() {
ValueLayout vChar = ValueLayout.JAVA_BYTE;
ValueLayout vShort = ValueLayout.JAVA_SHORT.withOrder(ByteOrder.BIG_ENDIAN);
ValueLayout vInt = ValueLayout.JAVA_INT.withOrder(ByteOrder.BIG_ENDIAN);
//mimic pragma pack(1)
GroupLayout g = MemoryLayout.structLayout(vChar.withByteAlignment(1).withName("a"),
vShort.withByteAlignment(1).withName("b"),
vInt.withByteAlignment(1).withName("c"));
assertEquals(g.byteAlignment(), 1);
VarHandle vh_c = g.varHandle(PathElement.groupElement("a"));
VarHandle vh_s = g.varHandle(PathElement.groupElement("b"));
VarHandle vh_i = g.varHandle(PathElement.groupElement("c"));
try (Arena arena = Arena.ofConfined()) {
MemorySegment segment = arena.allocate(g);;
vh_c.set(segment, Byte.MIN_VALUE);
assertEquals(vh_c.get(segment), Byte.MIN_VALUE);
vh_s.set(segment, Short.MIN_VALUE);
assertEquals(vh_s.get(segment), Short.MIN_VALUE);
vh_i.set(segment, Integer.MIN_VALUE);
assertEquals(vh_i.get(segment), Integer.MIN_VALUE);
}
}
@DataProvider(name = "alignments")
public Object[][] createAlignments() {
return LongStream.range(1, 20)
.mapToObj(v -> new Object[] { 1L << v })
.toArray(Object[][]::new);
}
}
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