/*
* Copyright (c) 2011, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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package org.graalvm.compiler.phases.common;
import org.graalvm.compiler.nodes.FixedNode;
import org.graalvm.compiler.nodes.StructuredGraph;
import org.graalvm.compiler.nodes.ValueNode;
import org.graalvm.compiler.nodes.extended.OSRMonitorEnterNode;
import org.graalvm.compiler.nodes.java.AccessMonitorNode;
import org.graalvm.compiler.nodes.java.MonitorEnterNode;
import org.graalvm.compiler.nodes.java.MonitorExitNode;
import org.graalvm.compiler.nodes.java.MonitorIdNode;
import org.graalvm.compiler.nodes.java.RawMonitorEnterNode;
import org.graalvm.compiler.nodes.util.GraphUtil;
import org.graalvm.compiler.phases.Phase;
public class LockEliminationPhase extends Phase {
@Override
protected void run(StructuredGraph graph) {
for (MonitorExitNode monitorExitNode : graph.getNodes(MonitorExitNode.TYPE)) {
FixedNode next = monitorExitNode.next();
if ((next instanceof MonitorEnterNode || next instanceof RawMonitorEnterNode)) {
// should never happen, osr monitor enters are always direct successors of the graph
// start
assert !(next instanceof OSRMonitorEnterNode);
AccessMonitorNode monitorEnterNode = (AccessMonitorNode) next;
if (isCompatibleLock(monitorEnterNode, monitorExitNode)) {
/*
* We've coarsened the lock so use the same monitor id for the whole region,
* otherwise the monitor operations appear to be unrelated.
*/
MonitorIdNode enterId = monitorEnterNode.getMonitorId();
MonitorIdNode exitId = monitorExitNode.getMonitorId();
if (enterId != exitId) {
enterId.replaceAndDelete(exitId);
}
GraphUtil.removeFixedWithUnusedInputs(monitorEnterNode);
GraphUtil.removeFixedWithUnusedInputs(monitorExitNode);
}
}
}
}
Check that the paired operations operate on the same object at the same lock depth.
/**
* Check that the paired operations operate on the same object at the same lock depth.
*/
public static boolean isCompatibleLock(AccessMonitorNode lock1, AccessMonitorNode lock2) {
/*
* It is not always the case that sequential monitor operations on the same object have the
* same lock depth: Escape analysis can have removed a lock operation that was in between,
* leading to a mismatch in lock depth.
*/
ValueNode object1 = GraphUtil.unproxify(lock1.object());
ValueNode object2 = GraphUtil.unproxify(lock2.object());
return object1 == object2 && lock1.getMonitorId().getLockDepth() == lock2.getMonitorId().getLockDepth();
}
}