/*
* Copyright (c) 2014, 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
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package org.graalvm.compiler.phases.graph;
import java.util.Map;
import java.util.function.ToDoubleFunction;
import org.graalvm.compiler.debug.Debug;
import org.graalvm.compiler.debug.DebugCounter;
import org.graalvm.compiler.graph.Node;
import org.graalvm.compiler.graph.NodeInputList;
import org.graalvm.compiler.nodes.AbstractBeginNode;
import org.graalvm.compiler.nodes.AbstractEndNode;
import org.graalvm.compiler.nodes.AbstractMergeNode;
import org.graalvm.compiler.nodes.ControlSplitNode;
import org.graalvm.compiler.nodes.EndNode;
import org.graalvm.compiler.nodes.FixedNode;
import org.graalvm.compiler.nodes.LoopBeginNode;
import org.graalvm.compiler.nodes.StartNode;
/**
* Compute probabilities for fixed nodes on the fly and cache them at {@link AbstractBeginNode}s.
*/
public class FixedNodeProbabilityCache implements ToDoubleFunction
* Given a {@link FixedNode} this method finds the most immediate {@link AbstractBeginNode}
* preceding it that either:
*
*
*
* The thus found {@link AbstractBeginNode} is equi-probable with the {@link FixedNode} it was * obtained from. When computed for the first time (afterwards a cache lookup returns it) that * probability is computed as follows, again depending on the begin-node's predecessor: *
* As an exception to all the above, a probability of 1 is assumed for a {@link FixedNode} that * appears to be dead-code (ie, lacks a predecessor). *
* */ @Override public double applyAsDouble(FixedNode node) { assert node != null; computeNodeProbabilityCounter.increment(); FixedNode current = findBegin(node); if (current == null) { // this should only appear for dead code return 1D; } assert current instanceof AbstractBeginNode; Double cachedValue = cache.get(current); if (cachedValue != null) { return cachedValue; } double probability = 0.0; if (current.predecessor() == null) { if (current instanceof AbstractMergeNode) { probability = handleMerge(current, probability); } else { assert current instanceof StartNode; probability = 1D; } } else { ControlSplitNode split = (ControlSplitNode) current.predecessor(); probability = split.probability((AbstractBeginNode) current) * applyAsDouble(split); } assert !Double.isNaN(probability) && !Double.isInfinite(probability) : current + " " + probability; cache.put(current, probability); return probability; } private double handleMerge(FixedNode current, double probability) { double result = probability; AbstractMergeNode currentMerge = (AbstractMergeNode) current; NodeInputList