Mercurial > hg > graal-compiler
view graal/com.oracle.graal.java/src/com/oracle/graal/java/ComputeLoopFrequenciesClosure.java @ 18993:480bd3b1adcd
Rename BeginNode => AbstractBeginNode.
author | Thomas Wuerthinger <thomas.wuerthinger@oracle.com> |
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date | Wed, 28 Jan 2015 00:50:31 +0100 |
parents | c88ab4f1f04a |
children | a2cb19764970 |
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/* * 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 com.oracle.graal.java; import static com.oracle.graal.nodes.cfg.ControlFlowGraph.*; import java.util.*; import java.util.stream.*; import com.oracle.graal.nodes.*; import com.oracle.graal.phases.graph.*; 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(MergeNode 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(); assert exitProbability <= 1D && exitProbability >= 0D; if (exitProbability < MIN_PROBABILITY) { exitProbability = MIN_PROBABILITY; } 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 1/{@link #MIN_PROBABILITY}. * * @return a times b saturated to 1/{@link #MIN_PROBABILITY} */ public static double multiplySaturate(double a, double b) { double r = a * b; if (r > 1 / MIN_PROBABILITY) { return 1 / MIN_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); } } }