| /* |
| * Copyright (c) 2011, 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.java; |
| |
| import java.util.List; |
| import java.util.Map; |
| import java.util.stream.Collectors; |
| |
| import org.graalvm.compiler.nodes.AbstractBeginNode; |
| import org.graalvm.compiler.nodes.AbstractMergeNode; |
| import org.graalvm.compiler.nodes.ControlSplitNode; |
| import org.graalvm.compiler.nodes.FixedNode; |
| import org.graalvm.compiler.nodes.LoopBeginNode; |
| import org.graalvm.compiler.nodes.LoopExitNode; |
| import org.graalvm.compiler.nodes.StructuredGraph; |
| import org.graalvm.compiler.nodes.cfg.ControlFlowGraph; |
| import org.graalvm.compiler.phases.Phase; |
| import org.graalvm.compiler.phases.graph.ReentrantNodeIterator; |
| |
| public final class ComputeLoopFrequenciesClosure extends ReentrantNodeIterator.NodeIteratorClosure<Double> { |
| |
| private static final ComputeLoopFrequenciesClosure INSTANCE = new ComputeLoopFrequenciesClosure(); |
| |
| private ComputeLoopFrequenciesClosure() { |
| // nothing to do |
| } |
| |
| @Override |
| protected Double processNode(FixedNode node, Double currentState) { |
| // normal nodes never change the probability of a path |
| return currentState; |
| } |
| |
| @Override |
| protected Double merge(AbstractMergeNode merge, List<Double> states) { |
| // a merge has the sum of all predecessor probabilities |
| return states.stream().collect(Collectors.summingDouble(d -> d)); |
| } |
| |
| @Override |
| protected Double afterSplit(AbstractBeginNode node, Double oldState) { |
| // a control split splits up the probability |
| ControlSplitNode split = (ControlSplitNode) node.predecessor(); |
| return oldState * split.probability(node); |
| } |
| |
| @Override |
| protected Map<LoopExitNode, Double> processLoop(LoopBeginNode loop, Double initialState) { |
| Map<LoopExitNode, Double> exitStates = ReentrantNodeIterator.processLoop(this, loop, 1D).exitStates; |
| |
| double exitProbability = exitStates.values().stream().mapToDouble(d -> d).sum(); |
| exitProbability = Math.min(1D, exitProbability); |
| if (exitProbability < ControlFlowGraph.MIN_PROBABILITY) { |
| exitProbability = ControlFlowGraph.MIN_PROBABILITY; |
| } |
| assert exitProbability <= 1D && exitProbability >= 0D; |
| double loopFrequency = 1D / exitProbability; |
| loop.setLoopFrequency(loopFrequency); |
| |
| double adjustmentFactor = initialState * loopFrequency; |
| exitStates.replaceAll((exitNode, probability) -> multiplySaturate(probability, adjustmentFactor)); |
| |
| return exitStates; |
| } |
| |
| /** |
| * Multiplies a and b and saturates the result to {@link ControlFlowGraph#MAX_PROBABILITY}. |
| */ |
| public static double multiplySaturate(double a, double b) { |
| double r = a * b; |
| if (r > ControlFlowGraph.MAX_PROBABILITY) { |
| return ControlFlowGraph.MAX_PROBABILITY; |
| } |
| return r; |
| } |
| |
| /** |
| * Computes the frequencies of all loops in the given graph. This is done by performing a |
| * reverse postorder iteration and computing the probability of all fixed nodes. The combined |
| * probability of all exits of a loop can be used to compute the loop's expected frequency. |
| */ |
| public static void compute(StructuredGraph graph) { |
| if (graph.hasLoops()) { |
| ReentrantNodeIterator.apply(INSTANCE, graph.start(), 1D); |
| } |
| } |
| |
| public static class ComputeLoopFrequencyPhase extends Phase { |
| |
| @Override |
| protected void run(StructuredGraph graph) { |
| compute(graph); |
| } |
| } |
| |
| public static final ComputeLoopFrequencyPhase PHASE_INSTANCE = new ComputeLoopFrequencyPhase(); |
| |
| } |