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/*
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* Copyright (c) 2012, 2016, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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package org.graalvm.compiler.loop;
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import static org.graalvm.compiler.core.common.GraalOptions.LoopMaxUnswitch;
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import static org.graalvm.compiler.core.common.GraalOptions.MaximumDesiredSize;
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import static org.graalvm.compiler.core.common.GraalOptions.MinimumPeelProbability;
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import java.util.List;
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import org.graalvm.compiler.core.common.util.UnsignedLong;
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import org.graalvm.compiler.debug.CounterKey;
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import org.graalvm.compiler.debug.DebugContext;
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import org.graalvm.compiler.graph.Node;
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import org.graalvm.compiler.graph.NodeBitMap;
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import org.graalvm.compiler.nodes.AbstractBeginNode;
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import org.graalvm.compiler.nodes.ControlSplitNode;
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import org.graalvm.compiler.nodes.DeoptimizeNode;
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import org.graalvm.compiler.nodes.FixedNode;
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import org.graalvm.compiler.nodes.FixedWithNextNode;
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import org.graalvm.compiler.nodes.InvokeNode;
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import org.graalvm.compiler.nodes.LoopBeginNode;
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import org.graalvm.compiler.nodes.MergeNode;
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import org.graalvm.compiler.nodes.StructuredGraph;
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import org.graalvm.compiler.nodes.VirtualState;
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import org.graalvm.compiler.nodes.VirtualState.VirtualClosure;
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import org.graalvm.compiler.nodes.cfg.Block;
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import org.graalvm.compiler.nodes.cfg.ControlFlowGraph;
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import org.graalvm.compiler.nodes.debug.ControlFlowAnchorNode;
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import org.graalvm.compiler.nodes.java.TypeSwitchNode;
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import org.graalvm.compiler.options.Option;
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import org.graalvm.compiler.options.OptionKey;
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import org.graalvm.compiler.options.OptionType;
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import org.graalvm.compiler.options.OptionValues;
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import jdk.vm.ci.meta.MetaAccessProvider;
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public class DefaultLoopPolicies implements LoopPolicies {
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public static class Options {
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@Option(help = "", type = OptionType.Expert) public static final OptionKey<Integer> LoopUnswitchMaxIncrease = new OptionKey<>(500);
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@Option(help = "", type = OptionType.Expert) public static final OptionKey<Integer> LoopUnswitchTrivial = new OptionKey<>(10);
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@Option(help = "", type = OptionType.Expert) public static final OptionKey<Double> LoopUnswitchFrequencyBoost = new OptionKey<>(10.0);
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@Option(help = "", type = OptionType.Expert) public static final OptionKey<Integer> FullUnrollMaxNodes = new OptionKey<>(300);
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@Option(help = "", type = OptionType.Expert) public static final OptionKey<Integer> FullUnrollMaxIterations = new OptionKey<>(600);
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@Option(help = "", type = OptionType.Expert) public static final OptionKey<Integer> ExactFullUnrollMaxNodes = new OptionKey<>(1200);
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@Option(help = "", type = OptionType.Expert) public static final OptionKey<Integer> ExactPartialUnrollMaxNodes = new OptionKey<>(200);
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@Option(help = "", type = OptionType.Expert) public static final OptionKey<Integer> UnrollMaxIterations = new OptionKey<>(16);
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}
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@Override
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public boolean shouldPeel(LoopEx loop, ControlFlowGraph cfg, MetaAccessProvider metaAccess) {
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LoopBeginNode loopBegin = loop.loopBegin();
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double entryProbability = cfg.blockFor(loopBegin.forwardEnd()).probability();
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OptionValues options = cfg.graph.getOptions();
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if (entryProbability > MinimumPeelProbability.getValue(options) && loop.size() + loopBegin.graph().getNodeCount() < MaximumDesiredSize.getValue(options)) {
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// check whether we're allowed to peel this loop
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return loop.canDuplicateLoop();
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} else {
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return false;
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}
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}
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@Override
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public boolean shouldFullUnroll(LoopEx loop) {
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if (!loop.isCounted() || !loop.counted().isConstantMaxTripCount()) {
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return false;
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}
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OptionValues options = loop.entryPoint().getOptions();
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CountedLoopInfo counted = loop.counted();
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UnsignedLong maxTrips = counted.constantMaxTripCount();
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if (maxTrips.equals(0)) {
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return loop.canDuplicateLoop();
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}
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int maxNodes = (counted.isExactTripCount() && counted.isConstantExactTripCount()) ? Options.ExactFullUnrollMaxNodes.getValue(options) : Options.FullUnrollMaxNodes.getValue(options);
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maxNodes = Math.min(maxNodes, Math.max(0, MaximumDesiredSize.getValue(options) - loop.loopBegin().graph().getNodeCount()));
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int size = Math.max(1, loop.size() - 1 - loop.loopBegin().phis().count());
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/* @formatter:off
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* The check below should not throw ArithmeticException because:
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* maxTrips is guaranteed to be >= 1 by the check above
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* - maxTrips * size can not overfow because:
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* - maxTrips <= FullUnrollMaxIterations <= Integer.MAX_VALUE
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* - 1 <= size <= Integer.MAX_VALUE
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* @formatter:on
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*/
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if (maxTrips.isLessOrEqualTo(Options.FullUnrollMaxIterations.getValue(options)) && maxTrips.minus(1).times(size).isLessOrEqualTo(maxNodes)) {
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// check whether we're allowed to unroll this loop
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return loop.canDuplicateLoop();
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} else {
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return false;
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}
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}
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@Override
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public boolean shouldPartiallyUnroll(LoopEx loop) {
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LoopBeginNode loopBegin = loop.loopBegin();
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if (!loop.isCounted()) {
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loopBegin.getDebug().log(DebugContext.VERBOSE_LEVEL, "shouldPartiallyUnroll %s isn't counted", loopBegin);
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return false;
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}
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OptionValues options = loop.entryPoint().getOptions();
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int maxNodes = Options.ExactPartialUnrollMaxNodes.getValue(options);
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maxNodes = Math.min(maxNodes, Math.max(0, MaximumDesiredSize.getValue(options) - loop.loopBegin().graph().getNodeCount()));
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int size = Math.max(1, loop.size() - 1 - loop.loopBegin().phis().count());
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int unrollFactor = loopBegin.getUnrollFactor();
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if (unrollFactor == 1) {
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double loopFrequency = loopBegin.loopFrequency();
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if (loopBegin.isSimpleLoop() && loopFrequency < 5.0) {
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loopBegin.getDebug().log(DebugContext.VERBOSE_LEVEL, "shouldPartiallyUnroll %s frequency too low %s ", loopBegin, loopFrequency);
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return false;
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}
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loopBegin.setLoopOrigFrequency(loopFrequency);
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}
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int maxUnroll = Options.UnrollMaxIterations.getValue(options);
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// Now correct size for the next unroll. UnrollMaxIterations == 1 means perform the
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// pre/main/post transformation but don't actually unroll the main loop.
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size += size;
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if (maxUnroll == 1 && loopBegin.isSimpleLoop() || size <= maxNodes && unrollFactor < maxUnroll) {
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// Will the next unroll fit?
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if ((int) loopBegin.loopOrigFrequency() < (unrollFactor * 2)) {
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return false;
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}
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// Check whether we're allowed to unroll this loop
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for (Node node : loop.inside().nodes()) {
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if (node instanceof ControlFlowAnchorNode) {
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return false;
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}
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if (node instanceof InvokeNode) {
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return false;
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}
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}
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return true;
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} else {
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loopBegin.getDebug().log(DebugContext.VERBOSE_LEVEL, "shouldPartiallyUnroll %s unrolled loop is too large %s ", loopBegin, size);
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return false;
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}
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}
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@Override
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public boolean shouldTryUnswitch(LoopEx loop) {
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LoopBeginNode loopBegin = loop.loopBegin();
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double loopFrequency = loopBegin.loopFrequency();
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if (loopFrequency <= 1.0) {
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return false;
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}
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OptionValues options = loop.entryPoint().getOptions();
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return loopBegin.unswitches() <= LoopMaxUnswitch.getValue(options);
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}
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private static final class CountingClosure implements VirtualClosure {
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int count;
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@Override
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public void apply(VirtualState node) {
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count++;
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}
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}
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private static class IsolatedInitialization {
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static final CounterKey UNSWITCH_SPLIT_WITH_PHIS = DebugContext.counter("UnswitchSplitWithPhis");
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}
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@Override
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public boolean shouldUnswitch(LoopEx loop, List<ControlSplitNode> controlSplits) {
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int phis = 0;
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StructuredGraph graph = loop.loopBegin().graph();
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DebugContext debug = graph.getDebug();
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NodeBitMap branchNodes = graph.createNodeBitMap();
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for (ControlSplitNode controlSplit : controlSplits) {
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for (Node successor : controlSplit.successors()) {
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AbstractBeginNode branch = (AbstractBeginNode) successor;
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// this may count twice because of fall-through in switches
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loop.nodesInLoopBranch(branchNodes, branch);
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}
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Block postDomBlock = loop.loopsData().getCFG().blockFor(controlSplit).getPostdominator();
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if (postDomBlock != null) {
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IsolatedInitialization.UNSWITCH_SPLIT_WITH_PHIS.increment(debug);
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phis += ((MergeNode) postDomBlock.getBeginNode()).phis().count();
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}
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}
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int inBranchTotal = branchNodes.count();
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CountingClosure stateNodesCount = new CountingClosure();
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double loopFrequency = loop.loopBegin().loopFrequency();
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OptionValues options = loop.loopBegin().getOptions();
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int maxDiff = Options.LoopUnswitchTrivial.getValue(options) + (int) (Options.LoopUnswitchFrequencyBoost.getValue(options) * (loopFrequency - 1.0 + phis));
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maxDiff = Math.min(maxDiff, Options.LoopUnswitchMaxIncrease.getValue(options));
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int remainingGraphSpace = MaximumDesiredSize.getValue(options) - graph.getNodeCount();
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maxDiff = Math.min(maxDiff, remainingGraphSpace);
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loop.loopBegin().stateAfter().applyToVirtual(stateNodesCount);
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int loopTotal = loop.size() - loop.loopBegin().phis().count() - stateNodesCount.count - 1;
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int actualDiff = (loopTotal - inBranchTotal);
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ControlSplitNode firstSplit = controlSplits.get(0);
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if (firstSplit instanceof TypeSwitchNode) {
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int copies = firstSplit.successors().count() - 1;
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for (Node succ : firstSplit.successors()) {
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FixedNode current = (FixedNode) succ;
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while (current instanceof FixedWithNextNode) {
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current = ((FixedWithNextNode) current).next();
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}
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if (current instanceof DeoptimizeNode) {
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copies--;
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}
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}
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actualDiff = actualDiff * copies;
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}
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debug.log("shouldUnswitch(%s, %s) : delta=%d (%.2f%% inside of branches), max=%d, f=%.2f, phis=%d -> %b", loop, controlSplits, actualDiff, (double) (inBranchTotal) / loopTotal * 100, maxDiff,
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loopFrequency, phis, actualDiff <= maxDiff);
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if (actualDiff <= maxDiff) {
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// check whether we're allowed to unswitch this loop
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return loop.canDuplicateLoop();
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} else {
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return false;
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}
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}
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}
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