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
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.graph.Node;
37 import org.graalvm.compiler.graph.NodeBitMap;
38 import org.graalvm.compiler.nodes.AbstractBeginNode;
39 import org.graalvm.compiler.nodes.ControlSplitNode;
40 import org.graalvm.compiler.nodes.DeoptimizeNode;
41 import org.graalvm.compiler.nodes.FixedNode;
42 import org.graalvm.compiler.nodes.FixedWithNextNode;
43 import org.graalvm.compiler.nodes.InvokeNode;
44 import org.graalvm.compiler.nodes.LoopBeginNode;
45 import org.graalvm.compiler.nodes.MergeNode;
46 import org.graalvm.compiler.nodes.StructuredGraph;
47 import org.graalvm.compiler.nodes.VirtualState;
48 import org.graalvm.compiler.nodes.VirtualState.VirtualClosure;
49 import org.graalvm.compiler.nodes.cfg.Block;
50 import org.graalvm.compiler.nodes.cfg.ControlFlowGraph;
51 import org.graalvm.compiler.nodes.debug.ControlFlowAnchorNode;
52 import org.graalvm.compiler.nodes.java.TypeSwitchNode;
53 import org.graalvm.compiler.options.Option;
54 import org.graalvm.compiler.options.OptionKey;
55 import org.graalvm.compiler.options.OptionType;
56 import org.graalvm.compiler.options.OptionValues;
57
58 import jdk.vm.ci.meta.MetaAccessProvider;
59
60 public class DefaultLoopPolicies implements LoopPolicies {
61
62 public static class Options {
63 @Option(help = "", type = OptionType.Expert) public static final OptionKey<Integer> LoopUnswitchMaxIncrease = new OptionKey<>(500);
64 @Option(help = "", type = OptionType.Expert) public static final OptionKey<Integer> LoopUnswitchTrivial = new OptionKey<>(10);
65 @Option(help = "", type = OptionType.Expert) public static final OptionKey<Double> LoopUnswitchFrequencyBoost = new OptionKey<>(10.0);
66
67 @Option(help = "", type = OptionType.Expert) public static final OptionKey<Integer> FullUnrollMaxNodes = new OptionKey<>(300);
68 @Option(help = "", type = OptionType.Expert) public static final OptionKey<Integer> FullUnrollMaxIterations = new OptionKey<>(600);
69 @Option(help = "", type = OptionType.Expert) public static final OptionKey<Integer> ExactFullUnrollMaxNodes = new OptionKey<>(1200);
70 @Option(help = "", type = OptionType.Expert) public static final OptionKey<Integer> ExactPartialUnrollMaxNodes = new OptionKey<>(200);
71
72 @Option(help = "", type = OptionType.Expert) public static final OptionKey<Integer> UnrollMaxIterations = new OptionKey<>(16);
73 }
74
75 @Override
76 public boolean shouldPeel(LoopEx loop, ControlFlowGraph cfg, MetaAccessProvider metaAccess) {
77 LoopBeginNode loopBegin = loop.loopBegin();
78 double entryProbability = cfg.blockFor(loopBegin.forwardEnd()).getRelativeFrequency();
79 OptionValues options = cfg.graph.getOptions();
80 if (entryProbability > MinimumPeelProbability.getValue(options) && loop.size() + loopBegin.graph().getNodeCount() < MaximumDesiredSize.getValue(options)) {
81 // check whether we're allowed to peel this loop
82 return loop.canDuplicateLoop();
83 } else {
84 return false;
85 }
86 }
87
88 @Override
89 public boolean shouldFullUnroll(LoopEx loop) {
90 if (!loop.isCounted() || !loop.counted().isConstantMaxTripCount()) {
91 return false;
92 }
93 OptionValues options = loop.entryPoint().getOptions();
94 CountedLoopInfo counted = loop.counted();
95 UnsignedLong maxTrips = counted.constantMaxTripCount();
96 if (maxTrips.equals(0)) {
97 return loop.canDuplicateLoop();
98 }
99 int maxNodes = (counted.isExactTripCount() && counted.isConstantExactTripCount()) ? Options.ExactFullUnrollMaxNodes.getValue(options) : Options.FullUnrollMaxNodes.getValue(options);
100 maxNodes = Math.min(maxNodes, Math.max(0, MaximumDesiredSize.getValue(options) - loop.loopBegin().graph().getNodeCount()));
101 int size = Math.max(1, loop.size() - 1 - loop.loopBegin().phis().count());
102 /* @formatter:off
103 * The check below should not throw ArithmeticException because:
104 * maxTrips is guaranteed to be >= 1 by the check above
105 * - maxTrips * size can not overfow because:
106 * - maxTrips <= FullUnrollMaxIterations <= Integer.MAX_VALUE
107 * - 1 <= size <= Integer.MAX_VALUE
108 * @formatter:on
109 */
110 if (maxTrips.isLessOrEqualTo(Options.FullUnrollMaxIterations.getValue(options)) && maxTrips.minus(1).times(size).isLessOrEqualTo(maxNodes)) {
111 // check whether we're allowed to unroll this loop
112 return loop.canDuplicateLoop();
113 } else {
114 return false;
115 }
116 }
117
118 @Override
119 public boolean shouldPartiallyUnroll(LoopEx loop) {
120 LoopBeginNode loopBegin = loop.loopBegin();
121 if (!loop.isCounted()) {
122 loopBegin.getDebug().log(DebugContext.VERBOSE_LEVEL, "shouldPartiallyUnroll %s isn't counted", loopBegin);
123 return false;
124 }
125 OptionValues options = loop.entryPoint().getOptions();
126 int maxNodes = Options.ExactPartialUnrollMaxNodes.getValue(options);
127 maxNodes = Math.min(maxNodes, Math.max(0, MaximumDesiredSize.getValue(options) - loop.loopBegin().graph().getNodeCount()));
128 int size = Math.max(1, loop.size() - 1 - loop.loopBegin().phis().count());
129 int unrollFactor = loopBegin.getUnrollFactor();
130 if (unrollFactor == 1) {
131 double loopFrequency = loopBegin.loopFrequency();
132 if (loopBegin.isSimpleLoop() && loopFrequency < 5.0) {
133 loopBegin.getDebug().log(DebugContext.VERBOSE_LEVEL, "shouldPartiallyUnroll %s frequency too low %s ", loopBegin, loopFrequency);
134 return false;
135 }
136 loopBegin.setLoopOrigFrequency(loopFrequency);
137 }
138 int maxUnroll = Options.UnrollMaxIterations.getValue(options);
139 // Now correct size for the next unroll. UnrollMaxIterations == 1 means perform the
140 // pre/main/post transformation but don't actually unroll the main loop.
141 size += size;
142 if (maxUnroll == 1 && loopBegin.isSimpleLoop() || size <= maxNodes && unrollFactor < maxUnroll) {
143 // Will the next unroll fit?
144 if ((int) loopBegin.loopOrigFrequency() < (unrollFactor * 2)) {
145 return false;
146 }
147 // Check whether we're allowed to unroll this loop
148 for (Node node : loop.inside().nodes()) {
149 if (node instanceof ControlFlowAnchorNode) {
150 return false;
151 }
152 if (node instanceof InvokeNode) {
153 return false;
154 }
155 }
156 return true;
157 } else {
158 loopBegin.getDebug().log(DebugContext.VERBOSE_LEVEL, "shouldPartiallyUnroll %s unrolled loop is too large %s ", loopBegin, size);
159 return false;
160 }
161 }
162
163 @Override
164 public boolean shouldTryUnswitch(LoopEx loop) {
165 LoopBeginNode loopBegin = loop.loopBegin();
166 double loopFrequency = loopBegin.loopFrequency();
167 if (loopFrequency <= 1.0) {
168 return false;
169 }
170 OptionValues options = loop.entryPoint().getOptions();
171 return loopBegin.unswitches() <= LoopMaxUnswitch.getValue(options);
172 }
173
174 private static final class CountingClosure implements VirtualClosure {
175 int count;
176
177 @Override
178 public void apply(VirtualState node) {
179 count++;
180 }
181 }
182
183 private static class IsolatedInitialization {
184 static final CounterKey UNSWITCH_SPLIT_WITH_PHIS = DebugContext.counter("UnswitchSplitWithPhis");
185 }
186
187 @Override
188 public boolean shouldUnswitch(LoopEx loop, List<ControlSplitNode> controlSplits) {
189 int phis = 0;
190 StructuredGraph graph = loop.loopBegin().graph();
191 DebugContext debug = graph.getDebug();
192 NodeBitMap branchNodes = graph.createNodeBitMap();
193 for (ControlSplitNode controlSplit : controlSplits) {
194 for (Node successor : controlSplit.successors()) {
195 AbstractBeginNode branch = (AbstractBeginNode) successor;
196 // this may count twice because of fall-through in switches
197 loop.nodesInLoopBranch(branchNodes, branch);
198 }
199 Block postDomBlock = loop.loopsData().getCFG().blockFor(controlSplit).getPostdominator();
200 if (postDomBlock != null) {
201 IsolatedInitialization.UNSWITCH_SPLIT_WITH_PHIS.increment(debug);
202 phis += ((MergeNode) postDomBlock.getBeginNode()).phis().count();
203 }
204 }
205 int inBranchTotal = branchNodes.count();
206
207 CountingClosure stateNodesCount = new CountingClosure();
208 double loopFrequency = loop.loopBegin().loopFrequency();
209 OptionValues options = loop.loopBegin().getOptions();
210 int maxDiff = Options.LoopUnswitchTrivial.getValue(options) + (int) (Options.LoopUnswitchFrequencyBoost.getValue(options) * (loopFrequency - 1.0 + phis));
211
212 maxDiff = Math.min(maxDiff, Options.LoopUnswitchMaxIncrease.getValue(options));
213 int remainingGraphSpace = MaximumDesiredSize.getValue(options) - graph.getNodeCount();
214 maxDiff = Math.min(maxDiff, remainingGraphSpace);
215
216 loop.loopBegin().stateAfter().applyToVirtual(stateNodesCount);
217 int loopTotal = loop.size() - loop.loopBegin().phis().count() - stateNodesCount.count - 1;
218 int actualDiff = (loopTotal - inBranchTotal);
219 ControlSplitNode firstSplit = controlSplits.get(0);
220 if (firstSplit instanceof TypeSwitchNode) {
221 int copies = firstSplit.successors().count() - 1;
222 for (Node succ : firstSplit.successors()) {
223 FixedNode current = (FixedNode) succ;
224 while (current instanceof FixedWithNextNode) {
225 current = ((FixedWithNextNode) current).next();
226 }
227 if (current instanceof DeoptimizeNode) {
228 copies--;
229 }
230 }
231 actualDiff = actualDiff * copies;
232 }
233
234 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,
235 loopFrequency, phis, actualDiff <= maxDiff);
236 if (actualDiff <= maxDiff) {
237 // check whether we're allowed to unswitch this loop
238 return loop.canDuplicateLoop();
239 } else {
240 return false;
241 }
242 }
243
244 }