1 /*
2 * Copyright (c) 2019, 2023, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 */
23
24 /*
25 * @test
26 * @enablePreview
27 * @run testng TestMemoryAlignment
28 */
29
30 import java.lang.foreign.*;
31 import java.lang.foreign.MemoryLayout.PathElement;
32 import java.lang.invoke.VarHandle;
33 import java.nio.ByteOrder;
34 import java.util.stream.LongStream;
35
36 import org.testng.annotations.*;
37 import static org.testng.Assert.*;
38
39 public class TestMemoryAlignment {
40
41 @Test(dataProvider = "alignments")
42 public void testAlignedAccess(long align) {
43 ValueLayout layout = ValueLayout.JAVA_INT
44 .withOrder(ByteOrder.BIG_ENDIAN);
45 assertEquals(layout.byteAlignment(), 4);
46 ValueLayout aligned = layout.withByteAlignment(align);
47 assertEquals(aligned.byteAlignment(), align); //unreasonable alignment here, to make sure access throws
48 VarHandle vh = aligned.varHandle();
49 try (Arena arena = Arena.ofConfined()) {
50 MemorySegment segment = arena.allocate(aligned);;
51 vh.set(segment, -42);
52 int val = (int)vh.get(segment);
53 assertEquals(val, -42);
54 }
55 }
56
57 @Test(dataProvider = "alignments")
58 public void testUnalignedAccess(long align) {
59 ValueLayout layout = ValueLayout.JAVA_INT
60 .withOrder(ByteOrder.BIG_ENDIAN);
61 assertEquals(layout.byteAlignment(), 4);
62 ValueLayout aligned = layout.withByteAlignment(align);
63 try (Arena arena = Arena.ofConfined()) {
64 MemoryLayout alignedGroup = MemoryLayout.structLayout(MemoryLayout.paddingLayout(1), aligned);
65 assertEquals(alignedGroup.byteAlignment(), align);
66 VarHandle vh = aligned.varHandle();
67 MemorySegment segment = arena.allocate(alignedGroup);;
68 vh.set(segment.asSlice(1L), -42);
69 assertEquals(align, 8); //this is the only case where access is aligned
70 } catch (IllegalArgumentException ex) {
71 assertNotEquals(align, 8); //if align != 8, access is always unaligned
72 }
73 }
74
75 @Test(dataProvider = "alignments")
76 public void testUnalignedPath(long align) {
77 MemoryLayout layout = ValueLayout.JAVA_INT.withOrder(ByteOrder.BIG_ENDIAN);
78 MemoryLayout aligned = layout.withByteAlignment(align).withName("value");
79 try {
80 GroupLayout alignedGroup = MemoryLayout.structLayout(MemoryLayout.paddingLayout(1), aligned);
81 alignedGroup.varHandle(PathElement.groupElement("value"));
82 assertEquals(align, 1); //this is the only case where path is aligned
83 } catch (IllegalArgumentException ex) {
84 assertNotEquals(align, 1); //if align != 8, path is always unaligned
85 }
86 }
87
88 @Test(dataProvider = "alignments")
89 public void testUnalignedSequence(long align) {
90 try {
91 SequenceLayout layout = MemoryLayout.sequenceLayout(5, ValueLayout.JAVA_INT.withOrder(ByteOrder.BIG_ENDIAN).withByteAlignment(align));
92 VarHandle vh = layout.varHandle(PathElement.sequenceElement());
93 try (Arena arena = Arena.ofConfined()) {
94 MemorySegment segment = arena.allocate(layout);;
95 for (long i = 0 ; i < 5 ; i++) {
96 vh.set(segment, i, -42);
97 }
98 }
99 } catch (IllegalArgumentException ex) {
100 assertTrue(align > 4); //if align > 4, access is always unaligned (for some elements)
101 }
102 }
103
104 @Test
105 public void testPackedAccess() {
106 ValueLayout vChar = ValueLayout.JAVA_BYTE;
107 ValueLayout vShort = ValueLayout.JAVA_SHORT.withOrder(ByteOrder.BIG_ENDIAN);
108 ValueLayout vInt = ValueLayout.JAVA_INT.withOrder(ByteOrder.BIG_ENDIAN);
109 //mimic pragma pack(1)
110 GroupLayout g = MemoryLayout.structLayout(vChar.withByteAlignment(1).withName("a"),
111 vShort.withByteAlignment(1).withName("b"),
112 vInt.withByteAlignment(1).withName("c"));
113 assertEquals(g.byteAlignment(), 1);
114 VarHandle vh_c = g.varHandle(PathElement.groupElement("a"));
115 VarHandle vh_s = g.varHandle(PathElement.groupElement("b"));
116 VarHandle vh_i = g.varHandle(PathElement.groupElement("c"));
117 try (Arena arena = Arena.ofConfined()) {
118 MemorySegment segment = arena.allocate(g);;
119 vh_c.set(segment, Byte.MIN_VALUE);
120 assertEquals(vh_c.get(segment), Byte.MIN_VALUE);
121 vh_s.set(segment, Short.MIN_VALUE);
122 assertEquals(vh_s.get(segment), Short.MIN_VALUE);
123 vh_i.set(segment, Integer.MIN_VALUE);
124 assertEquals(vh_i.get(segment), Integer.MIN_VALUE);
125 }
126 }
127
128 @DataProvider(name = "alignments")
129 public Object[][] createAlignments() {
130 return LongStream.range(1, 20)
131 .mapToObj(v -> new Object[] { 1L << v })
132 .toArray(Object[][]::new);
133 }
134 }