72 lines
2.8 KiB
Java
72 lines
2.8 KiB
Java
/*
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* Copyright (c) 2017, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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/*
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* @test
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* @bug 8178047
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* @run main/othervm -XX:CompileCommand=exclude,*.main -XX:-TieredCompilation -XX:-BackgroundCompilation compiler.unsafe.TestRawAliasing
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* @modules java.base/jdk.internal.misc:+open
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*/
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package compiler.unsafe;
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import java.lang.reflect.Field;
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public class TestRawAliasing {
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static private final jdk.internal.misc.Unsafe UNSAFE;
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static {
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try {
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Field f = jdk.internal.misc.Unsafe.class.getDeclaredField("theUnsafe");
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f.setAccessible(true);
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UNSAFE = (jdk.internal.misc.Unsafe) f.get(null);
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} catch (Exception e) {
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throw new RuntimeException("Unable to get Unsafe instance.", e);
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}
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}
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static private final int OFFSET_X = 50;
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static private final int OFFSET_Y = 100;
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private static int test(long base_plus_offset_x, long base_plus_offset_y, int magic_value) {
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// write 0 to a location
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UNSAFE.putByte(base_plus_offset_x - OFFSET_X, (byte)0);
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// write unfoldable value to really the same location with another base
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UNSAFE.putByte(base_plus_offset_y - OFFSET_Y, (byte)magic_value);
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// read the value back, should be equal to "unfoldable_value"
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return UNSAFE.getByte(base_plus_offset_x - OFFSET_X);
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}
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private static final int OFF_HEAP_AREA_SIZE = 128;
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private static final byte MAGIC = 123;
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// main is excluded from compilation since we don't want the test method to inline and make base values fold
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public static void main(String... args) {
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long base = UNSAFE.allocateMemory(OFF_HEAP_AREA_SIZE);
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for (int i = 0; i < 100_000; i++) {
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if (test(base + OFFSET_X, base + OFFSET_Y, MAGIC) != MAGIC) {
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throw new RuntimeException("Unexpected magic value");
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}
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}
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}
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}
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