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 * @run testng TestMemoryAlignment
27 */
28
29 import java.lang.foreign.*;
30 import java.lang.foreign.MemoryLayout.PathElement;
31 import java.lang.invoke.VarHandle;
32 import java.nio.ByteOrder;
33 import java.util.stream.LongStream;
34
35 import org.testng.annotations.*;
36 import static org.testng.Assert.*;
37
38 public class TestMemoryAlignment {
39
40 @Test(dataProvider = "alignments")
41 public void testAlignedAccess(long align) {
42 ValueLayout layout = ValueLayout.JAVA_INT
43 .withOrder(ByteOrder.BIG_ENDIAN);
44 assertEquals(layout.byteAlignment(), 4);
45 ValueLayout aligned = layout.withByteAlignment(align);
46 assertEquals(aligned.byteAlignment(), align); //unreasonable alignment here, to make sure access throws
47 VarHandle vh = aligned.varHandle();
48 try (Arena arena = Arena.ofConfined()) {
49 MemorySegment segment = arena.allocate(aligned);;
50 vh.set(segment, 0L, -42);
51 int val = (int)vh.get(segment, 0L);
52 assertEquals(val, -42);
53 }
54 }
55
56 @Test(dataProvider = "alignments")
57 public void testUnalignedAccess(long align) {
58 ValueLayout layout = ValueLayout.JAVA_INT
59 .withOrder(ByteOrder.BIG_ENDIAN);
60 assertEquals(layout.byteAlignment(), 4);
61 ValueLayout aligned = layout.withByteAlignment(align);
62 try (Arena arena = Arena.ofConfined()) {
63 MemoryLayout alignedGroup = MemoryLayout.structLayout(MemoryLayout.paddingLayout(1), aligned);
64 assertEquals(alignedGroup.byteAlignment(), align);
65 VarHandle vh = aligned.varHandle();
66 MemorySegment segment = arena.allocate(alignedGroup);;
67 vh.set(segment.asSlice(1L), 0L, -42);
68 assertEquals(align, 8); //this is the only case where access is aligned
69 } catch (IllegalArgumentException ex) {
70 assertNotEquals(align, 8); //if align != 8, access is always unaligned
71 }
72 }
73
74 @Test(dataProvider = "alignments")
75 public void testUnalignedPath(long align) {
76 MemoryLayout layout = ValueLayout.JAVA_INT.withOrder(ByteOrder.BIG_ENDIAN);
77 MemoryLayout aligned = layout.withByteAlignment(align).withName("value");
78 try {
79 GroupLayout alignedGroup = MemoryLayout.structLayout(MemoryLayout.paddingLayout(1), aligned);
80 alignedGroup.varHandle(PathElement.groupElement("value"));
81 assertEquals(align, 1); //this is the only case where path is aligned
82 } catch (IllegalArgumentException ex) {
83 assertNotEquals(align, 1); //if align != 8, path is always unaligned
84 }
85 }
86
87 @Test(dataProvider = "alignments")
88 public void testUnalignedSequence(long align) {
89 try {
90 SequenceLayout layout = MemoryLayout.sequenceLayout(5, ValueLayout.JAVA_INT.withOrder(ByteOrder.BIG_ENDIAN).withByteAlignment(align));
91 VarHandle vh = layout.varHandle(PathElement.sequenceElement());
92 try (Arena arena = Arena.ofConfined()) {
93 MemorySegment segment = arena.allocate(layout);;
94 for (long i = 0 ; i < 5 ; i++) {
95 vh.set(segment, 0L, i, -42);
96 }
97 }
98 } catch (IllegalArgumentException ex) {
99 assertTrue(align > 4); //if align > 4, access is always unaligned (for some elements)
100 }
101 }
102
103 @Test
104 public void testPackedAccess() {
105 ValueLayout vChar = ValueLayout.JAVA_BYTE;
106 ValueLayout vShort = ValueLayout.JAVA_SHORT.withOrder(ByteOrder.BIG_ENDIAN);
107 ValueLayout vInt = ValueLayout.JAVA_INT.withOrder(ByteOrder.BIG_ENDIAN);
108 //mimic pragma pack(1)
109 GroupLayout g = MemoryLayout.structLayout(vChar.withByteAlignment(1).withName("a"),
110 vShort.withByteAlignment(1).withName("b"),
111 vInt.withByteAlignment(1).withName("c"));
112 assertEquals(g.byteAlignment(), 1);
113 VarHandle vh_c = g.varHandle(PathElement.groupElement("a"));
114 VarHandle vh_s = g.varHandle(PathElement.groupElement("b"));
115 VarHandle vh_i = g.varHandle(PathElement.groupElement("c"));
116 try (Arena arena = Arena.ofConfined()) {
117 MemorySegment segment = arena.allocate(g);;
118 vh_c.set(segment, 0L, Byte.MIN_VALUE);
119 assertEquals(vh_c.get(segment, 0L), Byte.MIN_VALUE);
120 vh_s.set(segment, 0L, Short.MIN_VALUE);
121 assertEquals(vh_s.get(segment, 0L), Short.MIN_VALUE);
122 vh_i.set(segment, 0L, Integer.MIN_VALUE);
123 assertEquals(vh_i.get(segment, 0L), Integer.MIN_VALUE);
124 }
125 }
126
127 @DataProvider(name = "alignments")
128 public Object[][] createAlignments() {
129 return LongStream.range(1, 20)
130 .mapToObj(v -> new Object[] { 1L << v })
131 .toArray(Object[][]::new);
132 }
133 }