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 LoopBeginNode loopBegin = loop.loopBegin();
104 if (!loop.isCounted()) {
105 loopBegin.getDebug().log(DebugContext.VERBOSE_LEVEL, "shouldPartiallyUnroll %s isn't counted", loopBegin);
106 return false;
107 }
108 OptionValues options = loop.entryPoint().getOptions();
109 int maxNodes = ExactPartialUnrollMaxNodes.getValue(options);
110 maxNodes = Math.min(maxNodes, Math.max(0, MaximumDesiredSize.getValue(options) - loop.loopBegin().graph().getNodeCount()));
111 int size = Math.max(1, loop.size() - 1 - loop.loopBegin().phis().count());
112 int unrollFactor = loopBegin.getUnrollFactor();
113 if (unrollFactor == 1) {
114 double loopFrequency = loopBegin.loopFrequency();
115 if (loopBegin.isSimpleLoop() && loopFrequency < 5.0) {
116 loopBegin.getDebug().log(DebugContext.VERBOSE_LEVEL, "shouldPartiallyUnroll %s frequency too low %s ", loopBegin, loopFrequency);
117 return false;
118 }
119 loopBegin.setLoopOrigFrequency(loopFrequency);
120 }
121 int maxUnroll = UnrollMaxIterations.getValue(options);
122 // Now correct size for the next unroll. UnrollMaxIterations == 1 means perform the
123 // pre/main/post transformation but don't actually unroll the main loop.
124 size += size;
125 if (maxUnroll == 1 && loopBegin.isSimpleLoop() || size <= maxNodes && unrollFactor < maxUnroll) {
126 // Will the next unroll fit?
127 if ((int) loopBegin.loopOrigFrequency() < (unrollFactor * 2)) {
128 return false;
129 }
130 // Check whether we're allowed to unroll this loop
131 for (Node node : loop.inside().nodes()) {
132 if (node instanceof ControlFlowAnchorNode) {
133 return false;
134 }
135 if (node instanceof InvokeNode) {
136 return false;
137 }
138 }
139 return true;
140 } else {
141 loopBegin.getDebug().log(DebugContext.VERBOSE_LEVEL, "shouldPartiallyUnroll %s unrolled loop is too large %s ", loopBegin, size);
142 return false;
143 }
144 }
145
146 @Override
147 public boolean shouldTryUnswitch(LoopEx loop) {
148 LoopBeginNode loopBegin = loop.loopBegin();
149 double loopFrequency = loopBegin.loopFrequency();
150 if (loopFrequency <= 1.0) {
151 return false;
152 }
153 OptionValues options = loop.entryPoint().getOptions();
154 return loopBegin.unswitches() <= LoopMaxUnswitch.getValue(options);
155 }
156
157 private static final class CountingClosure implements VirtualClosure {
158 int count;
159
160 @Override
161 public void apply(VirtualState node) {
162 count++;
163 }
164 }
165
166 private static class IsolatedInitialization {
167 static final CounterKey UNSWITCH_SPLIT_WITH_PHIS = DebugContext.counter("UnswitchSplitWithPhis");
168 }
169
170 @Override
171 public boolean shouldUnswitch(LoopEx loop, List<ControlSplitNode> controlSplits) {
172 int phis = 0;
173 StructuredGraph graph = loop.loopBegin().graph();
174 DebugContext debug = graph.getDebug();
175 NodeBitMap branchNodes = graph.createNodeBitMap();
176 for (ControlSplitNode controlSplit : controlSplits) {
177 for (Node successor : controlSplit.successors()) {
178 AbstractBeginNode branch = (AbstractBeginNode) successor;
179 // this may count twice because of fall-through in switches
180 loop.nodesInLoopBranch(branchNodes, branch);
181 }
182 Block postDomBlock = loop.loopsData().getCFG().blockFor(controlSplit).getPostdominator();
183 if (postDomBlock != null) {
184 IsolatedInitialization.UNSWITCH_SPLIT_WITH_PHIS.increment(debug);
185 phis += ((MergeNode) postDomBlock.getBeginNode()).phis().count();
186 }
187 }
188 int inBranchTotal = branchNodes.count();
189
190 CountingClosure stateNodesCount = new CountingClosure();
191 double loopFrequency = loop.loopBegin().loopFrequency();
192 OptionValues options = loop.loopBegin().getOptions();
193 int maxDiff = LoopUnswitchTrivial.getValue(options) + (int) (LoopUnswitchFrequencyBoost.getValue(options) * (loopFrequency - 1.0 + phis));
194
195 maxDiff = Math.min(maxDiff, LoopUnswitchMaxIncrease.getValue(options));
196 int remainingGraphSpace = MaximumDesiredSize.getValue(options) - graph.getNodeCount();
197 maxDiff = Math.min(maxDiff, remainingGraphSpace);
198
199 loop.loopBegin().stateAfter().applyToVirtual(stateNodesCount);
200 int loopTotal = loop.size() - loop.loopBegin().phis().count() - stateNodesCount.count - 1;
201 int actualDiff = (loopTotal - inBranchTotal);
202 ControlSplitNode firstSplit = controlSplits.get(0);
203 if (firstSplit instanceof TypeSwitchNode) {
204 int copies = firstSplit.successors().count() - 1;
205 for (Node succ : firstSplit.successors()) {
206 FixedNode current = (FixedNode) succ;
207 while (current instanceof FixedWithNextNode) {
208 current = ((FixedWithNextNode) current).next();
209 }
210 if (current instanceof DeoptimizeNode) {
211 copies--;
212 }
213 }
214 actualDiff = actualDiff * copies;
215 }
216
217 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,
218 loopFrequency, phis, actualDiff <= maxDiff);
219 if (actualDiff <= maxDiff) {
220 // check whether we're allowed to unswitch this loop
221 return loop.canDuplicateLoop();
222 } else {
223 return false;
224 }
225 }
226
227 }