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* version 2 for more details (a copy is included in the LICENSE file that
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package org.graalvm.compiler.loop;
import static org.graalvm.compiler.core.common.GraalOptions.LoopMaxUnswitch;
import static org.graalvm.compiler.core.common.GraalOptions.MaximumDesiredSize;
import static org.graalvm.compiler.core.common.GraalOptions.MinimumPeelProbability;
import java.util.List;
import org.graalvm.compiler.debug.Debug;
import org.graalvm.compiler.debug.DebugCounter;
import org.graalvm.compiler.graph.Node;
import org.graalvm.compiler.graph.NodeBitMap;
import org.graalvm.compiler.nodes.AbstractBeginNode;
import org.graalvm.compiler.nodes.ControlSplitNode;
import org.graalvm.compiler.nodes.DeoptimizeNode;
import org.graalvm.compiler.nodes.FixedNode;
import org.graalvm.compiler.nodes.FixedWithNextNode;
import org.graalvm.compiler.nodes.LoopBeginNode;
import org.graalvm.compiler.nodes.MergeNode;
import org.graalvm.compiler.nodes.VirtualState;
import org.graalvm.compiler.nodes.VirtualState.VirtualClosure;
import org.graalvm.compiler.nodes.cfg.Block;
import org.graalvm.compiler.nodes.cfg.ControlFlowGraph;
import org.graalvm.compiler.nodes.java.TypeSwitchNode;
import org.graalvm.compiler.options.Option;
import org.graalvm.compiler.options.OptionType;
import org.graalvm.compiler.options.OptionValues;
import org.graalvm.compiler.options.OptionKey;
import jdk.vm.ci.meta.MetaAccessProvider;
public class DefaultLoopPolicies implements LoopPolicies {
@Option(help = "", type = OptionType.Expert) public static final OptionKey<Integer> LoopUnswitchMaxIncrease = new OptionKey<>(500);
@Option(help = "", type = OptionType.Expert) public static final OptionKey<Integer> LoopUnswitchTrivial = new OptionKey<>(10);
@Option(help = "", type = OptionType.Expert) public static final OptionKey<Double> LoopUnswitchFrequencyBoost = new OptionKey<>(10.0);
@Option(help = "", type = OptionType.Expert) public static final OptionKey<Integer> FullUnrollMaxNodes = new OptionKey<>(300);
@Option(help = "", type = OptionType.Expert) public static final OptionKey<Integer> FullUnrollMaxIterations = new OptionKey<>(600);
@Option(help = "", type = OptionType.Expert) public static final OptionKey<Integer> ExactFullUnrollMaxNodes = new OptionKey<>(1200);
@Override
public boolean shouldPeel(LoopEx loop, ControlFlowGraph cfg, MetaAccessProvider metaAccess) {
LoopBeginNode loopBegin = loop.loopBegin();
double entryProbability = cfg.blockFor(loopBegin.forwardEnd()).probability();
OptionValues options = cfg.graph.getOptions();
if (entryProbability > MinimumPeelProbability.getValue(options) && loop.size() + loopBegin.graph().getNodeCount() < MaximumDesiredSize.getValue(options)) {
// check whether we're allowed to peel this loop
return loop.canDuplicateLoop();
} else {
return false;
}
}
@Override
public boolean shouldFullUnroll(LoopEx loop) {
if (!loop.isCounted() || !loop.counted().isConstantMaxTripCount()) {
return false;
}
OptionValues options = loop.entryPoint().getOptions();
CountedLoopInfo counted = loop.counted();
long maxTrips = counted.constantMaxTripCount();
int maxNodes = (counted.isExactTripCount() && counted.isConstantExactTripCount()) ? ExactFullUnrollMaxNodes.getValue(options) : FullUnrollMaxNodes.getValue(options);
maxNodes = Math.min(maxNodes, Math.max(0, MaximumDesiredSize.getValue(options) - loop.loopBegin().graph().getNodeCount()));
int size = Math.max(1, loop.size() - 1 - loop.loopBegin().phis().count());
if (maxTrips <= FullUnrollMaxIterations.getValue(options) && size * (maxTrips - 1) <= maxNodes) {
// check whether we're allowed to unroll this loop
return loop.canDuplicateLoop();
} else {
return false;
}
}
@Override
public boolean shouldTryUnswitch(LoopEx loop) {
LoopBeginNode loopBegin = loop.loopBegin();
double loopFrequency = loopBegin.loopFrequency();
if (loopFrequency <= 1.0) {
return false;
}
OptionValues options = loop.entryPoint().getOptions();
return loopBegin.unswitches() <= LoopMaxUnswitch.getValue(options);
}
private static final class CountingClosure implements VirtualClosure {
int count;
@Override
public void apply(VirtualState node) {
count++;
}
}
private static class IsolatedInitialization {
static final DebugCounter UNSWITCH_SPLIT_WITH_PHIS = Debug.counter("UnswitchSplitWithPhis");
}
@Override
public boolean shouldUnswitch(LoopEx loop, List<ControlSplitNode> controlSplits) {
int phis = 0;
NodeBitMap branchNodes = loop.loopBegin().graph().createNodeBitMap();
for (ControlSplitNode controlSplit : controlSplits) {
for (Node successor : controlSplit.successors()) {
AbstractBeginNode branch = (AbstractBeginNode) successor;
// this may count twice because of fall-through in switches
loop.nodesInLoopBranch(branchNodes, branch);
}
Block postDomBlock = loop.loopsData().getCFG().blockFor(controlSplit).getPostdominator();
if (postDomBlock != null) {
IsolatedInitialization.UNSWITCH_SPLIT_WITH_PHIS.increment();
phis += ((MergeNode) postDomBlock.getBeginNode()).phis().count();
}
}
int inBranchTotal = branchNodes.count();
CountingClosure stateNodesCount = new CountingClosure();
double loopFrequency = loop.loopBegin().loopFrequency();
OptionValues options = loop.loopBegin().getOptions();
int maxDiff = LoopUnswitchTrivial.getValue(options) + (int) (LoopUnswitchFrequencyBoost.getValue(options) * (loopFrequency - 1.0 + phis));
maxDiff = Math.min(maxDiff, LoopUnswitchMaxIncrease.getValue(options));
int remainingGraphSpace = MaximumDesiredSize.getValue(options) - loop.loopBegin().graph().getNodeCount();
maxDiff = Math.min(maxDiff, remainingGraphSpace);
loop.loopBegin().stateAfter().applyToVirtual(stateNodesCount);
int loopTotal = loop.size() - loop.loopBegin().phis().count() - stateNodesCount.count - 1;
int actualDiff = (loopTotal - inBranchTotal);
ControlSplitNode firstSplit = controlSplits.get(0);
if (firstSplit instanceof TypeSwitchNode) {
int copies = firstSplit.successors().count() - 1;
for (Node succ : firstSplit.successors()) {
FixedNode current = (FixedNode) succ;
while (current instanceof FixedWithNextNode) {
current = ((FixedWithNextNode) current).next();
}
if (current instanceof DeoptimizeNode) {
copies--;
}
}
actualDiff = actualDiff * copies;
}
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,
loopFrequency, phis, actualDiff <= maxDiff);
if (actualDiff <= maxDiff) {
// check whether we're allowed to unswitch this loop
return loop.canDuplicateLoop();
} else {
return false;
}
}
}