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.Debug;
32 import org.graalvm.compiler.debug.DebugCounter;
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.LoopBeginNode;
41 import org.graalvm.compiler.nodes.MergeNode;
42 import org.graalvm.compiler.nodes.VirtualState;
43 import org.graalvm.compiler.nodes.VirtualState.VirtualClosure;
44 import org.graalvm.compiler.nodes.cfg.Block;
45 import org.graalvm.compiler.nodes.cfg.ControlFlowGraph;
46 import org.graalvm.compiler.nodes.java.TypeSwitchNode;
47 import org.graalvm.compiler.options.Option;
48 import org.graalvm.compiler.options.OptionType;
49 import org.graalvm.compiler.options.OptionValue;
50
51 import jdk.vm.ci.meta.MetaAccessProvider;
52
53 public class DefaultLoopPolicies implements LoopPolicies {
54 @Option(help = "", type = OptionType.Expert) public static final OptionValue<Integer> LoopUnswitchMaxIncrease = new OptionValue<>(500);
55 @Option(help = "", type = OptionType.Expert) public static final OptionValue<Integer> LoopUnswitchTrivial = new OptionValue<>(10);
56 @Option(help = "", type = OptionType.Expert) public static final OptionValue<Double> LoopUnswitchFrequencyBoost = new OptionValue<>(10.0);
57
58 @Option(help = "", type = OptionType.Expert) public static final OptionValue<Integer> FullUnrollMaxNodes = new OptionValue<>(300);
59 @Option(help = "", type = OptionType.Expert) public static final OptionValue<Integer> FullUnrollMaxIterations = new OptionValue<>(600);
60 @Option(help = "", type = OptionType.Expert) public static final OptionValue<Integer> ExactFullUnrollMaxNodes = new OptionValue<>(1200);
61
62 @Override
63 public boolean shouldPeel(LoopEx loop, ControlFlowGraph cfg, MetaAccessProvider metaAccess) {
64 LoopBeginNode loopBegin = loop.loopBegin();
65 double entryProbability = cfg.blockFor(loopBegin.forwardEnd()).probability();
66 if (entryProbability > MinimumPeelProbability.getValue() && loop.size() + loopBegin.graph().getNodeCount() < MaximumDesiredSize.getValue()) {
67 // check whether we're allowed to peel this loop
68 return loop.canDuplicateLoop();
69 } else {
70 return false;
71 }
72 }
73
74 @Override
75 public boolean shouldFullUnroll(LoopEx loop) {
76 if (!loop.isCounted() || !loop.counted().isConstantMaxTripCount()) {
77 return false;
78 }
79 CountedLoopInfo counted = loop.counted();
80 long maxTrips = counted.constantMaxTripCount();
81 int maxNodes = (counted.isExactTripCount() && counted.isConstantExactTripCount()) ? ExactFullUnrollMaxNodes.getValue() : FullUnrollMaxNodes.getValue();
82 maxNodes = Math.min(maxNodes, Math.max(0, MaximumDesiredSize.getValue() - loop.loopBegin().graph().getNodeCount()));
83 int size = Math.max(1, loop.size() - 1 - loop.loopBegin().phis().count());
84 if (maxTrips <= FullUnrollMaxIterations.getValue() && size * (maxTrips - 1) <= maxNodes) {
85 // check whether we're allowed to unroll this loop
86 return loop.canDuplicateLoop();
87 } else {
88 return false;
89 }
90 }
91
92 @Override
93 public boolean shouldTryUnswitch(LoopEx loop) {
94 LoopBeginNode loopBegin = loop.loopBegin();
95 double loopFrequency = loopBegin.loopFrequency();
96 if (loopFrequency <= 1.0) {
97 return false;
98 }
99 return loopBegin.unswitches() <= LoopMaxUnswitch.getValue();
100 }
101
102 private static final class CountingClosure implements VirtualClosure {
103 int count;
104
105 @Override
106 public void apply(VirtualState node) {
107 count++;
108 }
109 }
110
111 private static class IsolatedInitialization {
112 static final DebugCounter UNSWITCH_SPLIT_WITH_PHIS = Debug.counter("UnswitchSplitWithPhis");
113 }
114
115 @Override
116 public boolean shouldUnswitch(LoopEx loop, List<ControlSplitNode> controlSplits) {
117 int phis = 0;
118 NodeBitMap branchNodes = loop.loopBegin().graph().createNodeBitMap();
119 for (ControlSplitNode controlSplit : controlSplits) {
120 for (Node successor : controlSplit.successors()) {
121 AbstractBeginNode branch = (AbstractBeginNode) successor;
122 // this may count twice because of fall-through in switches
123 loop.nodesInLoopBranch(branchNodes, branch);
124 }
125 Block postDomBlock = loop.loopsData().getCFG().blockFor(controlSplit).getPostdominator();
126 if (postDomBlock != null) {
127 IsolatedInitialization.UNSWITCH_SPLIT_WITH_PHIS.increment();
128 phis += ((MergeNode) postDomBlock.getBeginNode()).phis().count();
129 }
130 }
131 int inBranchTotal = branchNodes.count();
132
133 CountingClosure stateNodesCount = new CountingClosure();
134 double loopFrequency = loop.loopBegin().loopFrequency();
135 int maxDiff = LoopUnswitchTrivial.getValue() + (int) (LoopUnswitchFrequencyBoost.getValue() * (loopFrequency - 1.0 + phis));
136
137 maxDiff = Math.min(maxDiff, LoopUnswitchMaxIncrease.getValue());
138 int remainingGraphSpace = MaximumDesiredSize.getValue() - loop.loopBegin().graph().getNodeCount();
139 maxDiff = Math.min(maxDiff, remainingGraphSpace);
140
141 loop.loopBegin().stateAfter().applyToVirtual(stateNodesCount);
142 int loopTotal = loop.size() - loop.loopBegin().phis().count() - stateNodesCount.count - 1;
143 int actualDiff = (loopTotal - inBranchTotal);
144 ControlSplitNode firstSplit = controlSplits.get(0);
145 if (firstSplit instanceof TypeSwitchNode) {
146 int copies = firstSplit.successors().count() - 1;
147 for (Node succ : firstSplit.successors()) {
148 FixedNode current = (FixedNode) succ;
149 while (current instanceof FixedWithNextNode) {
150 current = ((FixedWithNextNode) current).next();
151 }
152 if (current instanceof DeoptimizeNode) {
153 copies--;
154 }
155 }
156 actualDiff = actualDiff * copies;
157 }
158
159 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,
160 loopFrequency, phis, actualDiff <= maxDiff);
161 if (actualDiff <= maxDiff) {
162 // check whether we're allowed to unswitch this loop
163 return loop.canDuplicateLoop();
164 } else {
165 return false;
166 }
167 }
168
169 }