/*
* Copyright (C) 2016 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 java.lang.reflect.Field;
import java.util.concurrent.atomic.AtomicBoolean;
import sun.misc.Unsafe;
/**
* Checker test on the 1.8 unsafe operations. Note, this is by no means an
* exhaustive unit test for these CAS (compare-and-swap) and fence operations.
* Instead, this test ensures the methods are recognized as intrinsic and behave
* as expected.
*/
public class Main {
private static final Unsafe unsafe = getUnsafe();
private static Thread[] sThreads = new Thread[10];
//
// Fields accessed by setters and adders, and by memory fence tests.
//
public int i = 0;
public long l = 0;
public Object o = null;
public int x_value;
public int y_value;
public volatile boolean running;
//
// Setters.
//
/// CHECK-START: int Main.set32(java.lang.Object, long, int) intrinsics_recognition (after)
/// CHECK-DAG: <<Result:i\d+>> InvokeVirtual intrinsic:UnsafeGetAndSetInt
/// CHECK-DAG: Return [<<Result>>]
private static int set32(Object o, long offset, int newValue) {
return unsafe.getAndSetInt(o, offset, newValue);
}
/// CHECK-START: long Main.set64(java.lang.Object, long, long) intrinsics_recognition (after)
/// CHECK-DAG: <<Result:j\d+>> InvokeVirtual intrinsic:UnsafeGetAndSetLong
/// CHECK-DAG: Return [<<Result>>]
private static long set64(Object o, long offset, long newValue) {
return unsafe.getAndSetLong(o, offset, newValue);
}
/// CHECK-START: java.lang.Object Main.setObj(java.lang.Object, long, java.lang.Object) intrinsics_recognition (after)
/// CHECK-DAG: <<Result:l\d+>> InvokeVirtual intrinsic:UnsafeGetAndSetObject
/// CHECK-DAG: Return [<<Result>>]
private static Object setObj(Object o, long offset, Object newValue) {
return unsafe.getAndSetObject(o, offset, newValue);
}
//
// Adders.
//
/// CHECK-START: int Main.add32(java.lang.Object, long, int) intrinsics_recognition (after)
/// CHECK-DAG: <<Result:i\d+>> InvokeVirtual intrinsic:UnsafeGetAndAddInt
/// CHECK-DAG: Return [<<Result>>]
private static int add32(Object o, long offset, int delta) {
return unsafe.getAndAddInt(o, offset, delta);
}
/// CHECK-START: long Main.add64(java.lang.Object, long, long) intrinsics_recognition (after)
/// CHECK-DAG: <<Result:j\d+>> InvokeVirtual intrinsic:UnsafeGetAndAddLong
/// CHECK-DAG: Return [<<Result>>]
private static long add64(Object o, long offset, long delta) {
return unsafe.getAndAddLong(o, offset, delta);
}
//
// Fences (native).
//
/// CHECK-START: void Main.load() intrinsics_recognition (after)
/// CHECK-DAG: InvokeVirtual intrinsic:UnsafeLoadFence
//
/// CHECK-START: void Main.load() instruction_simplifier (after)
/// CHECK-NOT: InvokeVirtual intrinsic:UnsafeLoadFence
//
/// CHECK-START: void Main.load() instruction_simplifier (after)
/// CHECK-DAG: MemoryBarrier kind:LoadAny
private static void load() {
unsafe.loadFence();
}
/// CHECK-START: void Main.store() intrinsics_recognition (after)
/// CHECK-DAG: InvokeVirtual intrinsic:UnsafeStoreFence
//
/// CHECK-START: void Main.store() instruction_simplifier (after)
/// CHECK-NOT: InvokeVirtual intrinsic:UnsafeStoreFence
//
/// CHECK-START: void Main.store() instruction_simplifier (after)
/// CHECK-DAG: MemoryBarrier kind:AnyStore
private static void store() {
unsafe.storeFence();
}
/// CHECK-START: void Main.full() intrinsics_recognition (after)
/// CHECK-DAG: InvokeVirtual intrinsic:UnsafeFullFence
//
/// CHECK-START: void Main.full() instruction_simplifier (after)
/// CHECK-NOT: InvokeVirtual intrinsic:UnsafeFullFence
//
/// CHECK-START: void Main.full() instruction_simplifier (after)
/// CHECK-DAG: MemoryBarrier kind:AnyAny
private static void full() {
unsafe.fullFence();
}
//
// Thread fork/join.
//
private static void fork(Runnable r) {
for (int i = 0; i < 10; i++) {
sThreads[i] = new Thread(r);
}
// Start the threads only after the full array has been written with new threads,
// because one test relies on the contents of this array to be consistent.
for (int i = 0; i < 10; i++) {
sThreads[i].start();
}
}
private static void join() {
try {
for (int i = 0; i < 10; i++) {
sThreads[i].join();
}
} catch (InterruptedException e) {
throw new Error("Failed join: " + e);
}
}
//
// Driver.
//
public static void main(String[] args) {
System.out.println("starting");
final Main m = new Main();
// Get the offsets.
final long intOffset, longOffset, objOffset;
try {
Field intField = Main.class.getDeclaredField("i");
Field longField = Main.class.getDeclaredField("l");
Field objField = Main.class.getDeclaredField("o");
intOffset = unsafe.objectFieldOffset(intField);
longOffset = unsafe.objectFieldOffset(longField);
objOffset = unsafe.objectFieldOffset(objField);
} catch (NoSuchFieldException e) {
throw new Error("No offset: " + e);
}
// Some sanity on setters and adders within same thread.
set32(m, intOffset, 3);
expectEqual32(3, m.i);
set64(m, longOffset, 7L);
expectEqual64(7L, m.l);
setObj(m, objOffset, m);
expectEqualObj(m, m.o);
add32(m, intOffset, 11);
expectEqual32(14, m.i);
add64(m, longOffset, 13L);
expectEqual64(20L, m.l);
// Some sanity on setters within different threads.
fork(new Runnable() {
public void run() {
for (int i = 0; i < 10; i++)
set32(m, intOffset, i);
}
});
join();
expectEqual32(9, m.i); // one thread's last value wins
fork(new Runnable() {
public void run() {
for (int i = 0; i < 10; i++)
set64(m, longOffset, (long) (100 + i));
}
});
join();
expectEqual64(109L, m.l); // one thread's last value wins
fork(new Runnable() {
public void run() {
for (int i = 0; i < 10; i++)
setObj(m, objOffset, sThreads[i]);
}
});
join();
expectEqualObj(sThreads[9], m.o); // one thread's last value wins
// Some sanity on adders within different threads.
fork(new Runnable() {
public void run() {
for (int i = 0; i < 10; i++)
add32(m, intOffset, i + 1);
}
});
join();
expectEqual32(559, m.i); // all values accounted for
fork(new Runnable() {
public void run() {
for (int i = 0; i < 10; i++)
add64(m, longOffset, (long) (i + 1));
}
});
join();
expectEqual64(659L, m.l); // all values accounted for
// Some sanity on fences within same thread. Note that memory fences within one
// thread make little sense, but the sanity check ensures nothing bad happens.
m.i = -1;
m.l = -2L;
m.o = null;
load();
store();
full();
expectEqual32(-1, m.i);
expectEqual64(-2L, m.l);
expectEqualObj(null, m.o);
// Some sanity on full fence within different threads. We write the non-volatile m.l after
// the fork(), which means there is no happens-before relation in the Java memory model
// with respect to the read in the threads. This relation is enforced by the memory fences
// and the weak-set() -> get() guard. Note that the guard semantics used here are actually
// too strong and already enforce total memory visibility, but this test illustrates what
// should still happen if Java had a true relaxed memory guard.
final AtomicBoolean guard1 = new AtomicBoolean();
m.l = 0L;
fork(new Runnable() {
public void run() {
while (!guard1.get()); // busy-waiting
full();
expectEqual64(-123456789L, m.l);
}
});
m.l = -123456789L;
full();
while (!guard1.weakCompareAndSet(false, true)); // relaxed memory order
join();
// Some sanity on release/acquire fences within different threads. We write the non-volatile
// m.l after the fork(), which means there is no happens-before relation in the Java memory
// model with respect to the read in the threads. This relation is enforced by the memory fences
// and the weak-set() -> get() guard. Note that the guard semantics used here are actually
// too strong and already enforce total memory visibility, but this test illustrates what
// should still happen if Java had a true relaxed memory guard.
final AtomicBoolean guard2 = new AtomicBoolean();
m.l = 0L;
fork(new Runnable() {
public void run() {
while (!guard2.get()); // busy-waiting
load();
expectEqual64(-987654321L, m.l);
}
});
m.l = -987654321L;
store();
while (!guard2.weakCompareAndSet(false, true)); // relaxed memory order
join();
// Some sanity on release/acquire fences within different threads using a test suggested by
// Hans Boehm. Even this test remains with the realm of sanity only, since having the threads
// read the same value consistently would be a valid outcome.
m.x_value = -1;
m.y_value = -1;
m.running = true;
fork(new Runnable() {
public void run() {
while (m.running) {
for (int few_times = 0; few_times < 1000; few_times++) {
// Read y first, then load fence, then read x.
// They should appear in order, if seen at all.
int local_y = m.y_value;
load();
int local_x = m.x_value;
expectLessThanOrEqual32(local_y, local_x);
}
}
}
});
for (int many_times = 0; many_times < 100000; many_times++) {
m.x_value = many_times;
store();
m.y_value = many_times;
}
m.running = false;
join();
// All done!
System.out.println("passed");
}
// Use reflection to implement "Unsafe.getUnsafe()";
private static Unsafe getUnsafe() {
try {
Class<?> unsafeClass = Unsafe.class;
Field f = unsafeClass.getDeclaredField("theUnsafe");
f.setAccessible(true);
return (Unsafe) f.get(null);
} catch (Exception e) {
throw new Error("Cannot get Unsafe instance");
}
}
private static void expectEqual32(int expected, int result) {
if (expected != result) {
throw new Error("Expected: " + expected + ", found: " + result);
}
}
private static void expectLessThanOrEqual32(int val1, int val2) {
if (val1 > val2) {
throw new Error("Expected: " + val1 + " <= " + val2);
}
}
private static void expectEqual64(long expected, long result) {
if (expected != result) {
throw new Error("Expected: " + expected + ", found: " + result);
}
}
private static void expectEqualObj(Object expected, Object result) {
if (expected != result) {
throw new Error("Expected: " + expected + ", found: " + result);
}
}
}