1 /* 2 * Copyright (c) 2012, 2018, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 */ 23 24 25 package org.graalvm.compiler.loop; 26 27 import static org.graalvm.compiler.core.common.GraalOptions.LoopMaxUnswitch; 28 import static org.graalvm.compiler.core.common.GraalOptions.MaximumDesiredSize; 29 import static org.graalvm.compiler.core.common.GraalOptions.MinimumPeelProbability; 30 31 import java.util.List; 32 33 import org.graalvm.compiler.core.common.util.UnsignedLong; 34 import org.graalvm.compiler.debug.CounterKey; 35 import org.graalvm.compiler.debug.DebugContext; 36 import org.graalvm.compiler.debug.GraalError; 37 import org.graalvm.compiler.graph.Node; 38 import org.graalvm.compiler.graph.NodeBitMap; 39 import org.graalvm.compiler.nodes.AbstractBeginNode; 40 import org.graalvm.compiler.nodes.ControlSplitNode; 41 import org.graalvm.compiler.nodes.DeoptimizeNode; 42 import org.graalvm.compiler.nodes.FixedNode; 43 import org.graalvm.compiler.nodes.FixedWithNextNode; 44 import org.graalvm.compiler.nodes.InvokeNode; 45 import org.graalvm.compiler.nodes.LoopBeginNode; 46 import org.graalvm.compiler.nodes.MergeNode; 47 import org.graalvm.compiler.nodes.StructuredGraph; 48 import org.graalvm.compiler.nodes.VirtualState; 49 import org.graalvm.compiler.nodes.VirtualState.VirtualClosure; 50 import org.graalvm.compiler.nodes.calc.CompareNode; 51 import org.graalvm.compiler.nodes.cfg.Block; 52 import org.graalvm.compiler.nodes.cfg.ControlFlowGraph; 53 import org.graalvm.compiler.nodes.debug.ControlFlowAnchorNode; 54 import org.graalvm.compiler.nodes.java.TypeSwitchNode; 55 import org.graalvm.compiler.options.Option; 56 import org.graalvm.compiler.options.OptionKey; 57 import org.graalvm.compiler.options.OptionType; 58 import org.graalvm.compiler.options.OptionValues; 59 60 import jdk.vm.ci.meta.MetaAccessProvider; 61 62 public class DefaultLoopPolicies implements LoopPolicies { 63 64 public static class Options { 65 @Option(help = "", type = OptionType.Expert) public static final OptionKey<Integer> LoopUnswitchMaxIncrease = new OptionKey<>(500); 66 @Option(help = "", type = OptionType.Expert) public static final OptionKey<Integer> LoopUnswitchTrivial = new OptionKey<>(10); 67 @Option(help = "", type = OptionType.Expert) public static final OptionKey<Double> LoopUnswitchFrequencyBoost = new OptionKey<>(10.0); 68 69 @Option(help = "", type = OptionType.Expert) public static final OptionKey<Integer> FullUnrollMaxNodes = new OptionKey<>(400); 70 @Option(help = "", type = OptionType.Expert) public static final OptionKey<Integer> FullUnrollConstantCompareBoost = new OptionKey<>(15); 71 @Option(help = "", type = OptionType.Expert) public static final OptionKey<Integer> FullUnrollMaxIterations = new OptionKey<>(600); 72 @Option(help = "", type = OptionType.Expert) public static final OptionKey<Integer> ExactFullUnrollMaxNodes = new OptionKey<>(800); 73 @Option(help = "", type = OptionType.Expert) public static final OptionKey<Integer> ExactPartialUnrollMaxNodes = new OptionKey<>(200); 74 75 @Option(help = "", type = OptionType.Expert) public static final OptionKey<Integer> UnrollMaxIterations = new OptionKey<>(16); 76 } 77 78 @Override 79 public boolean shouldPeel(LoopEx loop, ControlFlowGraph cfg, MetaAccessProvider metaAccess) { 80 LoopBeginNode loopBegin = loop.loopBegin(); 81 double entryProbability = cfg.blockFor(loopBegin.forwardEnd()).getRelativeFrequency(); 82 OptionValues options = cfg.graph.getOptions(); 83 if (entryProbability > MinimumPeelProbability.getValue(options) && loop.size() + loopBegin.graph().getNodeCount() < MaximumDesiredSize.getValue(options)) { 84 // check whether we're allowed to peel this loop 85 return loop.canDuplicateLoop(); 86 } else { 87 return false; 88 } 89 } 90 91 @Override 92 public boolean shouldFullUnroll(LoopEx loop) { 93 if (!loop.isCounted() || !loop.counted().isConstantMaxTripCount() || !loop.counted().counterNeverOverflows()) { 94 return false; 95 } 96 OptionValues options = loop.entryPoint().getOptions(); 97 CountedLoopInfo counted = loop.counted(); 98 UnsignedLong maxTrips = counted.constantMaxTripCount(); 99 if (maxTrips.equals(0)) { 100 return loop.canDuplicateLoop(); 101 } 102 if (maxTrips.isGreaterThan(Options.FullUnrollMaxIterations.getValue(options))) { 103 return false; 104 } 105 int globalMax = MaximumDesiredSize.getValue(options) - loop.loopBegin().graph().getNodeCount(); 106 if (globalMax <= 0) { 107 return false; 108 } 109 int maxNodes = counted.isExactTripCount() ? Options.ExactFullUnrollMaxNodes.getValue(options) : Options.FullUnrollMaxNodes.getValue(options); 110 for (Node usage : counted.getCounter().valueNode().usages()) { 111 if (usage instanceof CompareNode) { 112 CompareNode compare = (CompareNode) usage; 113 if (compare.getY().isConstant()) { 114 maxNodes += Options.FullUnrollConstantCompareBoost.getValue(options); 115 } 116 } 117 } 118 maxNodes = Math.min(maxNodes, globalMax); 119 int size = loop.inside().nodes().count(); 120 size -= 2; // remove the counted if and its non-exit begin 121 size -= loop.loopBegin().loopEnds().count(); 122 GraalError.guarantee(size >= 0, "Wrong size"); 123 /* @formatter:off 124 * The check below should not throw ArithmeticException because: 125 * maxTrips is guaranteed to be >= 1 by the check above 126 * - maxTrips * size can not overfow because: 127 * - maxTrips <= FullUnrollMaxIterations <= Integer.MAX_VALUE 128 * - 1 <= size <= Integer.MAX_VALUE 129 * @formatter:on 130 */ 131 if (maxTrips.minus(1).times(size).isLessOrEqualTo(maxNodes)) { 132 // check whether we're allowed to unroll this loop 133 return loop.canDuplicateLoop(); 134 } else { 135 return false; 136 } 137 } 138 139 @Override 140 public boolean shouldPartiallyUnroll(LoopEx loop) { 141 LoopBeginNode loopBegin = loop.loopBegin(); 142 if (!loop.isCounted()) { 143 loopBegin.getDebug().log(DebugContext.VERBOSE_LEVEL, "shouldPartiallyUnroll %s isn't counted", loopBegin); 144 return false; 145 } 146 OptionValues options = loop.entryPoint().getOptions(); 147 int maxNodes = Options.ExactPartialUnrollMaxNodes.getValue(options); 148 maxNodes = Math.min(maxNodes, Math.max(0, MaximumDesiredSize.getValue(options) - loop.loopBegin().graph().getNodeCount())); 149 int size = Math.max(1, loop.size() - 1 - loop.loopBegin().phis().count()); 150 int unrollFactor = loopBegin.getUnrollFactor(); 151 if (unrollFactor == 1) { 152 double loopFrequency = loopBegin.loopFrequency(); 153 if (loopBegin.isSimpleLoop() && loopFrequency < 5.0) { 154 loopBegin.getDebug().log(DebugContext.VERBOSE_LEVEL, "shouldPartiallyUnroll %s frequency too low %s ", loopBegin, loopFrequency); 155 return false; 156 } 157 loopBegin.setLoopOrigFrequency(loopFrequency); 158 } 159 int maxUnroll = Options.UnrollMaxIterations.getValue(options); 160 // Now correct size for the next unroll. UnrollMaxIterations == 1 means perform the 161 // pre/main/post transformation but don't actually unroll the main loop. 162 size += size; 163 if (maxUnroll == 1 && loopBegin.isSimpleLoop() || size <= maxNodes && unrollFactor < maxUnroll) { 164 // Will the next unroll fit? 165 if ((int) loopBegin.loopOrigFrequency() < (unrollFactor * 2)) { 166 return false; 167 } 168 // Check whether we're allowed to unroll this loop 169 for (Node node : loop.inside().nodes()) { 170 if (node instanceof ControlFlowAnchorNode) { 171 return false; 172 } 173 if (node instanceof InvokeNode) { 174 return false; 175 } 176 } 177 return true; 178 } else { 179 loopBegin.getDebug().log(DebugContext.VERBOSE_LEVEL, "shouldPartiallyUnroll %s unrolled loop is too large %s ", loopBegin, size); 180 return false; 181 } 182 } 183 184 @Override 185 public boolean shouldTryUnswitch(LoopEx loop) { 186 LoopBeginNode loopBegin = loop.loopBegin(); 187 double loopFrequency = loopBegin.loopFrequency(); 188 if (loopFrequency <= 1.0) { 189 return false; 190 } 191 OptionValues options = loop.entryPoint().getOptions(); 192 return loopBegin.unswitches() <= LoopMaxUnswitch.getValue(options); 193 } 194 195 private static final class CountingClosure implements VirtualClosure { 196 int count; 197 198 @Override 199 public void apply(VirtualState node) { 200 count++; 201 } 202 } 203 204 private static class IsolatedInitialization { 205 static final CounterKey UNSWITCH_SPLIT_WITH_PHIS = DebugContext.counter("UnswitchSplitWithPhis"); 206 } 207 208 @Override 209 public boolean shouldUnswitch(LoopEx loop, List<ControlSplitNode> controlSplits) { 210 int phis = 0; 211 StructuredGraph graph = loop.loopBegin().graph(); 212 DebugContext debug = graph.getDebug(); 213 NodeBitMap branchNodes = graph.createNodeBitMap(); 214 for (ControlSplitNode controlSplit : controlSplits) { 215 for (Node successor : controlSplit.successors()) { 216 AbstractBeginNode branch = (AbstractBeginNode) successor; 217 // this may count twice because of fall-through in switches 218 loop.nodesInLoopBranch(branchNodes, branch); 219 } 220 Block postDomBlock = loop.loopsData().getCFG().blockFor(controlSplit).getPostdominator(); 221 if (postDomBlock != null) { 222 IsolatedInitialization.UNSWITCH_SPLIT_WITH_PHIS.increment(debug); 223 phis += ((MergeNode) postDomBlock.getBeginNode()).phis().count(); 224 } 225 } 226 int inBranchTotal = branchNodes.count(); 227 228 CountingClosure stateNodesCount = new CountingClosure(); 229 double loopFrequency = loop.loopBegin().loopFrequency(); 230 OptionValues options = loop.loopBegin().getOptions(); 231 int maxDiff = Options.LoopUnswitchTrivial.getValue(options) + (int) (Options.LoopUnswitchFrequencyBoost.getValue(options) * (loopFrequency - 1.0 + phis)); 232 233 maxDiff = Math.min(maxDiff, Options.LoopUnswitchMaxIncrease.getValue(options)); 234 int remainingGraphSpace = MaximumDesiredSize.getValue(options) - graph.getNodeCount(); 235 maxDiff = Math.min(maxDiff, remainingGraphSpace); 236 237 loop.loopBegin().stateAfter().applyToVirtual(stateNodesCount); 238 int loopTotal = loop.size() - loop.loopBegin().phis().count() - stateNodesCount.count - 1; 239 int actualDiff = (loopTotal - inBranchTotal); 240 ControlSplitNode firstSplit = controlSplits.get(0); 241 if (firstSplit instanceof TypeSwitchNode) { 242 int copies = firstSplit.successors().count() - 1; 243 for (Node succ : firstSplit.successors()) { 244 FixedNode current = (FixedNode) succ; 245 while (current instanceof FixedWithNextNode) { 246 current = ((FixedWithNextNode) current).next(); 247 } 248 if (current instanceof DeoptimizeNode) { 249 copies--; 250 } 251 } 252 actualDiff = actualDiff * copies; 253 } 254 255 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, 256 loopFrequency, phis, actualDiff <= maxDiff); 257 if (actualDiff <= maxDiff) { 258 // check whether we're allowed to unswitch this loop 259 return loop.canDuplicateLoop(); 260 } else { 261 return false; 262 } 263 } 264 }