1 /*
2 * Copyright (c) 2012, 2016, 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 package org.graalvm.compiler.loop;
24
25 import static org.graalvm.compiler.core.common.GraalOptions.LoopMaxUnswitch;
26 import static org.graalvm.compiler.core.common.GraalOptions.MaximumDesiredSize;
27 import static org.graalvm.compiler.core.common.GraalOptions.MinimumPeelProbability;
28
29 import java.util.List;
30
31 import org.graalvm.compiler.debug.CounterKey;
32 import org.graalvm.compiler.debug.DebugContext;
33 import org.graalvm.compiler.graph.Node;
34 import org.graalvm.compiler.graph.NodeBitMap;
35 import org.graalvm.compiler.nodes.AbstractBeginNode;
36 import org.graalvm.compiler.nodes.ControlSplitNode;
37 import org.graalvm.compiler.nodes.DeoptimizeNode;
38 import org.graalvm.compiler.nodes.FixedNode;
39 import org.graalvm.compiler.nodes.FixedWithNextNode;
40 import org.graalvm.compiler.nodes.InvokeNode;
41 import org.graalvm.compiler.nodes.LoopBeginNode;
42 import org.graalvm.compiler.nodes.MergeNode;
43 import org.graalvm.compiler.nodes.StructuredGraph;
44 import org.graalvm.compiler.nodes.VirtualState;
45 import org.graalvm.compiler.nodes.VirtualState.VirtualClosure;
46 import org.graalvm.compiler.nodes.cfg.Block;
47 import org.graalvm.compiler.nodes.cfg.ControlFlowGraph;
48 import org.graalvm.compiler.nodes.debug.ControlFlowAnchorNode;
49 import org.graalvm.compiler.nodes.java.TypeSwitchNode;
50 import org.graalvm.compiler.options.Option;
51 import org.graalvm.compiler.options.OptionKey;
52 import org.graalvm.compiler.options.OptionType;
53 import org.graalvm.compiler.options.OptionValues;
54
55 import jdk.vm.ci.meta.MetaAccessProvider;
56
57 public class DefaultLoopPolicies implements LoopPolicies {
58
59 public static class Options {
60 @Option(help = "", type = OptionType.Expert) public static final OptionKey<Integer> LoopUnswitchMaxIncrease = new OptionKey<>(500);
61 @Option(help = "", type = OptionType.Expert) public static final OptionKey<Integer> LoopUnswitchTrivial = new OptionKey<>(10);
62 @Option(help = "", type = OptionType.Expert) public static final OptionKey<Double> LoopUnswitchFrequencyBoost = new OptionKey<>(10.0);
63
64 @Option(help = "", type = OptionType.Expert) public static final OptionKey<Integer> FullUnrollMaxNodes = new OptionKey<>(300);
65 @Option(help = "", type = OptionType.Expert) public static final OptionKey<Integer> FullUnrollMaxIterations = new OptionKey<>(600);
66 @Option(help = "", type = OptionType.Expert) public static final OptionKey<Integer> ExactFullUnrollMaxNodes = new OptionKey<>(1200);
67 @Option(help = "", type = OptionType.Expert) public static final OptionKey<Integer> ExactPartialUnrollMaxNodes = new OptionKey<>(200);
68
69 @Option(help = "", type = OptionType.Expert) public static final OptionKey<Integer> UnrollMaxIterations = new OptionKey<>(16);
70 }
71
72 @Override
73 public boolean shouldPeel(LoopEx loop, ControlFlowGraph cfg, MetaAccessProvider metaAccess) {
74 LoopBeginNode loopBegin = loop.loopBegin();
75 double entryProbability = cfg.blockFor(loopBegin.forwardEnd()).probability();
76 OptionValues options = cfg.graph.getOptions();
77 if (entryProbability > MinimumPeelProbability.getValue(options) && loop.size() + loopBegin.graph().getNodeCount() < MaximumDesiredSize.getValue(options)) {
78 // check whether we're allowed to peel this loop
79 return loop.canDuplicateLoop();
80 } else {
81 return false;
82 }
83 }
84
85 @Override
86 public boolean shouldFullUnroll(LoopEx loop) {
87 if (!loop.isCounted() || !loop.counted().isConstantMaxTripCount()) {
88 return false;
89 }
90 OptionValues options = loop.entryPoint().getOptions();
91 CountedLoopInfo counted = loop.counted();
92 long maxTrips = counted.constantMaxTripCount();
93 int maxNodes = (counted.isExactTripCount() && counted.isConstantExactTripCount()) ? Options.ExactFullUnrollMaxNodes.getValue(options) : Options.FullUnrollMaxNodes.getValue(options);
94 maxNodes = Math.min(maxNodes, Math.max(0, MaximumDesiredSize.getValue(options) - loop.loopBegin().graph().getNodeCount()));
95 int size = Math.max(1, loop.size() - 1 - loop.loopBegin().phis().count());
96 if (maxTrips <= Options.FullUnrollMaxIterations.getValue(options) && size * (maxTrips - 1) <= maxNodes) {
97 // check whether we're allowed to unroll this loop
98 return loop.canDuplicateLoop();
99 } else {
100 return false;
101 }
102 }
103
104 @Override
105 public boolean shouldPartiallyUnroll(LoopEx loop) {
106 LoopBeginNode loopBegin = loop.loopBegin();
107 if (!loop.isCounted()) {
108 loopBegin.getDebug().log(DebugContext.VERBOSE_LEVEL, "shouldPartiallyUnroll %s isn't counted", loopBegin);
109 return false;
110 }
111 OptionValues options = loop.entryPoint().getOptions();
112 int maxNodes = Options.ExactPartialUnrollMaxNodes.getValue(options);
113 maxNodes = Math.min(maxNodes, Math.max(0, MaximumDesiredSize.getValue(options) - loop.loopBegin().graph().getNodeCount()));
114 int size = Math.max(1, loop.size() - 1 - loop.loopBegin().phis().count());
115 int unrollFactor = loopBegin.getUnrollFactor();
116 if (unrollFactor == 1) {
117 double loopFrequency = loopBegin.loopFrequency();
118 if (loopBegin.isSimpleLoop() && loopFrequency < 5.0) {
119 loopBegin.getDebug().log(DebugContext.VERBOSE_LEVEL, "shouldPartiallyUnroll %s frequency too low %s ", loopBegin, loopFrequency);
120 return false;
121 }
122 loopBegin.setLoopOrigFrequency(loopFrequency);
123 }
124 int maxUnroll = Options.UnrollMaxIterations.getValue(options);
125 // Now correct size for the next unroll. UnrollMaxIterations == 1 means perform the
126 // pre/main/post transformation but don't actually unroll the main loop.
127 size += size;
128 if (maxUnroll == 1 && loopBegin.isSimpleLoop() || size <= maxNodes && unrollFactor < maxUnroll) {
129 // Will the next unroll fit?
130 if ((int) loopBegin.loopOrigFrequency() < (unrollFactor * 2)) {
131 return false;
132 }
133 // Check whether we're allowed to unroll this loop
134 for (Node node : loop.inside().nodes()) {
135 if (node instanceof ControlFlowAnchorNode) {
136 return false;
137 }
138 if (node instanceof InvokeNode) {
139 return false;
140 }
141 }
142 return true;
143 } else {
144 loopBegin.getDebug().log(DebugContext.VERBOSE_LEVEL, "shouldPartiallyUnroll %s unrolled loop is too large %s ", loopBegin, size);
145 return false;
146 }
147 }
148
149 @Override
150 public boolean shouldTryUnswitch(LoopEx loop) {
151 LoopBeginNode loopBegin = loop.loopBegin();
152 double loopFrequency = loopBegin.loopFrequency();
153 if (loopFrequency <= 1.0) {
154 return false;
155 }
156 OptionValues options = loop.entryPoint().getOptions();
157 return loopBegin.unswitches() <= LoopMaxUnswitch.getValue(options);
158 }
159
160 private static final class CountingClosure implements VirtualClosure {
161 int count;
162
163 @Override
164 public void apply(VirtualState node) {
165 count++;
166 }
167 }
168
169 private static class IsolatedInitialization {
170 static final CounterKey UNSWITCH_SPLIT_WITH_PHIS = DebugContext.counter("UnswitchSplitWithPhis");
171 }
172
173 @Override
174 public boolean shouldUnswitch(LoopEx loop, List<ControlSplitNode> controlSplits) {
175 int phis = 0;
176 StructuredGraph graph = loop.loopBegin().graph();
177 DebugContext debug = graph.getDebug();
178 NodeBitMap branchNodes = graph.createNodeBitMap();
179 for (ControlSplitNode controlSplit : controlSplits) {
180 for (Node successor : controlSplit.successors()) {
181 AbstractBeginNode branch = (AbstractBeginNode) successor;
182 // this may count twice because of fall-through in switches
183 loop.nodesInLoopBranch(branchNodes, branch);
184 }
185 Block postDomBlock = loop.loopsData().getCFG().blockFor(controlSplit).getPostdominator();
186 if (postDomBlock != null) {
187 IsolatedInitialization.UNSWITCH_SPLIT_WITH_PHIS.increment(debug);
188 phis += ((MergeNode) postDomBlock.getBeginNode()).phis().count();
189 }
190 }
191 int inBranchTotal = branchNodes.count();
192
193 CountingClosure stateNodesCount = new CountingClosure();
194 double loopFrequency = loop.loopBegin().loopFrequency();
195 OptionValues options = loop.loopBegin().getOptions();
196 int maxDiff = Options.LoopUnswitchTrivial.getValue(options) + (int) (Options.LoopUnswitchFrequencyBoost.getValue(options) * (loopFrequency - 1.0 + phis));
197
198 maxDiff = Math.min(maxDiff, Options.LoopUnswitchMaxIncrease.getValue(options));
199 int remainingGraphSpace = MaximumDesiredSize.getValue(options) - graph.getNodeCount();
200 maxDiff = Math.min(maxDiff, remainingGraphSpace);
201
202 loop.loopBegin().stateAfter().applyToVirtual(stateNodesCount);
203 int loopTotal = loop.size() - loop.loopBegin().phis().count() - stateNodesCount.count - 1;
204 int actualDiff = (loopTotal - inBranchTotal);
205 ControlSplitNode firstSplit = controlSplits.get(0);
206 if (firstSplit instanceof TypeSwitchNode) {
207 int copies = firstSplit.successors().count() - 1;
208 for (Node succ : firstSplit.successors()) {
209 FixedNode current = (FixedNode) succ;
210 while (current instanceof FixedWithNextNode) {
211 current = ((FixedWithNextNode) current).next();
212 }
213 if (current instanceof DeoptimizeNode) {
214 copies--;
215 }
216 }
217 actualDiff = actualDiff * copies;
218 }
219
220 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,
221 loopFrequency, phis, actualDiff <= maxDiff);
222 if (actualDiff <= maxDiff) {
223 // check whether we're allowed to unswitch this loop
224 return loop.canDuplicateLoop();
225 } else {
226 return false;
227 }
228 }
229
230 }