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/*
* Copyright (C) 2015 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
import sun.misc.Unsafe;
import java.lang.reflect.Field;
public class Main {
long instanceField;
static long myLongField1;
static long myLongField2;
public static void main(String[] args) throws Exception {
Unsafe unsafe = getUnsafe();
Main f = new Main();
long offset = unsafe.objectFieldOffset(Main.class.getDeclaredField("instanceField"));
getUnsafe(); // spill offset
long a = myLongField1;
// We used the hinted register for the low part of b, which is EBX, as requested
// by the intrinsic below. Allocating EBX for the low part, would put ESP as the high
// part, and we did not check that ESP was blocked.
long b = myLongField2;
unsafe.compareAndSwapLong(f, offset, a, b);
}
private static Unsafe getUnsafe() throws Exception {
Field f = Unsafe.class.getDeclaredField("theUnsafe");
f.setAccessible(true);
return (Unsafe) f.get(null);
}
}
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