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 }