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