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The GraalVM compiler and the Graal-truffle optimizer.
/*
* Copyright (c) 2013, 2023, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
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package org.graalvm.compiler.phases.common;
import java.util.Optional;
import org.graalvm.compiler.core.common.type.Stamp;
import org.graalvm.compiler.debug.DebugCloseable;
import org.graalvm.compiler.debug.DebugContext;
import org.graalvm.compiler.debug.GraalError;
import org.graalvm.compiler.graph.Graph;
import org.graalvm.compiler.graph.Node;
import org.graalvm.compiler.nodes.AbstractBeginNode;
import org.graalvm.compiler.nodes.AbstractMergeNode;
import org.graalvm.compiler.nodes.BeginNode;
import org.graalvm.compiler.nodes.ConstantNode;
import org.graalvm.compiler.nodes.EndNode;
import org.graalvm.compiler.nodes.GraphState;
import org.graalvm.compiler.nodes.GraphState.StageFlag;
import org.graalvm.compiler.nodes.GuardPhiNode;
import org.graalvm.compiler.nodes.IfNode;
import org.graalvm.compiler.nodes.LogicNode;
import org.graalvm.compiler.nodes.MergeNode;
import org.graalvm.compiler.nodes.NodeView;
import org.graalvm.compiler.nodes.ShortCircuitOrNode;
import org.graalvm.compiler.nodes.StructuredGraph;
import org.graalvm.compiler.nodes.ValueNode;
import org.graalvm.compiler.nodes.calc.AbstractNormalizeCompareNode;
import org.graalvm.compiler.nodes.calc.ConditionalNode;
import org.graalvm.compiler.nodes.spi.CoreProviders;
public class ExpandLogicPhase extends PostRunCanonicalizationPhase {
private static final double EPSILON = 1E-6;
public ExpandLogicPhase(CanonicalizerPhase canonicalizer) {
super(canonicalizer);
}
@Override
public Optional notApplicableTo(GraphState graphState) {
return NotApplicable.ifAny(
super.notApplicableTo(graphState),
NotApplicable.ifApplied(this, StageFlag.EXPAND_LOGIC, graphState),
NotApplicable.unlessRunAfter(this, StageFlag.LOW_TIER_LOWERING, graphState));
}
@Override
protected void run(StructuredGraph graph, CoreProviders context) {
expandLogic(graph);
}
@SuppressWarnings("try")
public static void expandLogic(StructuredGraph graph) {
for (ShortCircuitOrNode logic : graph.getNodes(ShortCircuitOrNode.TYPE)) {
expandBinary(logic);
}
assert graph.getNodes(ShortCircuitOrNode.TYPE).isEmpty();
for (AbstractNormalizeCompareNode logic : graph.getNodes(AbstractNormalizeCompareNode.TYPE)) {
try (DebugCloseable s = logic.withNodeSourcePosition()) {
processNormalizeCompareNode(logic);
}
}
}
@Override
public void updateGraphState(GraphState graphState) {
super.updateGraphState(graphState);
graphState.setAfterStage(StageFlag.EXPAND_LOGIC);
}
private static void processNormalizeCompareNode(AbstractNormalizeCompareNode normalize) {
StructuredGraph graph = normalize.graph();
LogicNode equalComp = graph.addOrUniqueWithInputs(normalize.createEqualComparison());
LogicNode lessComp = graph.addOrUniqueWithInputs(normalize.createLowerComparison());
Stamp stamp = normalize.stamp(NodeView.DEFAULT);
ConditionalNode equalValue = graph.unique(new ConditionalNode(equalComp, ConstantNode.forIntegerStamp(stamp, 0, graph), ConstantNode.forIntegerStamp(stamp, 1, graph)));
ConditionalNode value = graph.unique(new ConditionalNode(lessComp, ConstantNode.forIntegerStamp(stamp, -1, graph), equalValue));
normalize.replaceAtUsagesAndDelete(value);
}
@SuppressWarnings("try")
private static void expandBinary(ShortCircuitOrNode binary) {
while (binary.usages().isNotEmpty()) {
Node usage = binary.usages().first();
try (DebugCloseable nsp = usage.withNodeSourcePosition()) {
if (usage instanceof ShortCircuitOrNode) {
expandBinary((ShortCircuitOrNode) usage);
} else if (usage instanceof IfNode) {
processIf(binary.getX(), binary.isXNegated(), binary.getY(), binary.isYNegated(), (IfNode) usage, binary.getShortCircuitProbability().getDesignatedSuccessorProbability());
} else if (usage instanceof ConditionalNode) {
processConditional(binary.getX(), binary.isXNegated(), binary.getY(), binary.isYNegated(), (ConditionalNode) usage);
} else {
throw GraalError.shouldNotReachHereUnexpectedValue(usage); // ExcludeFromJacocoGeneratedReport
}
}
}
binary.safeDelete();
}
private static void processIf(LogicNode x, boolean xNegated, LogicNode y, boolean yNegated, IfNode ifNode, double shortCircuitProbability) {
processIf(x, xNegated, y, yNegated, ifNode, shortCircuitProbability, false);
}
/**
* Expand the given logic {@code or} node represented by {@code x} and {@code y} to actual
* control flow at the given {@code ifNode} original usage.
*
* For example the code shape
*
*
* if (x || y) {
* a();
* } else {
* b();
* }
*
*
* will be expanded to
*
*
* if(x){
* goto trueMerge;
* } else {
* if(y) {
* goto trueMerge;
* }else {
* goto falseMerge;
* }
* }
* trueMerge:
* a();
* falseMerge:
* b();
*
*
* If {@code createGuardPhi == true} this method will return a {@code GuardPhiNode} on the
* {@code trueMerge} with the two true successor branches as guard inputs.
*/
public static GuardPhiNode processIf(LogicNode x, boolean xNegated, LogicNode y, boolean yNegated, IfNode ifNode, double shortCircuitProbability, boolean createGuardPhi) {
/*
* this method splits an IfNode, which has a ShortCircuitOrNode as its condition, into two
* separate IfNodes: if(X) and if(Y)
*
* for computing the probabilities P(X) and P(Y), we use two different approaches. The first
* one assumes that the shortCircuitProbability and the probability on the IfNode were
* created with each other in mind. If this assumption does not hold, we fall back to
* another mechanism for computing the probabilities.
*/
AbstractBeginNode trueTarget = ifNode.trueSuccessor();
AbstractBeginNode falseTarget = ifNode.falseSuccessor();
GuardPhiNode guardPhi = null;
// 1st approach
// assumption: P(originalIf.trueSuccessor) == P(X) + ((1 - P(X)) * P(Y))
double firstIfTrueProbability = shortCircuitProbability;
double secondIfTrueProbability = sanitizeProbability((ifNode.getTrueSuccessorProbability() - shortCircuitProbability) / (1 - shortCircuitProbability));
double expectedOriginalIfTrueProbability = firstIfTrueProbability + (1 - firstIfTrueProbability) * secondIfTrueProbability;
if (!doubleEquals(ifNode.getTrueSuccessorProbability(), expectedOriginalIfTrueProbability)) {
/*
* 2nd approach
*
* the assumption above did not hold, so we either used an artificial probability as
* shortCircuitProbability or the ShortCircuitOrNode was moved to some other IfNode.
*
* so, we distribute the if's trueSuccessorProbability between the newly generated if
* nodes according to the shortCircuitProbability. the following invariant is always
* true in this case: P(originalIf.trueSuccessor) == P(X) + ((1 - P(X)) * P(Y))
*/
firstIfTrueProbability = ifNode.getTrueSuccessorProbability() * shortCircuitProbability;
secondIfTrueProbability = sanitizeProbability(1 - (ifNode.probability(falseTarget) / (1 - firstIfTrueProbability)));
}
ifNode.clearSuccessors();
Graph graph = ifNode.graph();
AbstractMergeNode trueTargetMerge = graph.add(new MergeNode());
trueTargetMerge.setNext(trueTarget);
EndNode firstTrueEnd = graph.add(new EndNode());
EndNode secondTrueEnd = graph.add(new EndNode());
trueTargetMerge.addForwardEnd(firstTrueEnd);
trueTargetMerge.addForwardEnd(secondTrueEnd);
AbstractBeginNode firstTrueTarget = BeginNode.begin(firstTrueEnd);
firstTrueTarget.setNodeSourcePosition(trueTarget.getNodeSourcePosition());
AbstractBeginNode secondTrueTarget = BeginNode.begin(secondTrueEnd);
secondTrueTarget.setNodeSourcePosition(trueTarget.getNodeSourcePosition());
if (yNegated) {
secondIfTrueProbability = 1.0 - secondIfTrueProbability;
}
if (xNegated) {
firstIfTrueProbability = 1.0 - firstIfTrueProbability;
}
IfNode secondIf = new IfNode(y, yNegated ? falseTarget : secondTrueTarget, yNegated ? secondTrueTarget : falseTarget, ifNode.getProfileData().copy(secondIfTrueProbability));
secondIf.setNodeSourcePosition(ifNode.getNodeSourcePosition());
AbstractBeginNode secondIfBegin = BeginNode.begin(graph.add(secondIf));
secondIfBegin.setNodeSourcePosition(falseTarget.getNodeSourcePosition());
IfNode firstIf = graph.add(new IfNode(x, xNegated ? secondIfBegin : firstTrueTarget, xNegated ? firstTrueTarget : secondIfBegin, ifNode.getProfileData().copy(firstIfTrueProbability)));
firstIf.setNodeSourcePosition(ifNode.getNodeSourcePosition());
ifNode.replaceAtPredecessor(firstIf);
ifNode.safeDelete();
graph.getDebug().dump(DebugContext.VERY_DETAILED_LEVEL, graph, "After processing if %s", ifNode);
if (createGuardPhi) {
guardPhi = graph.addWithoutUnique(new GuardPhiNode(trueTargetMerge));
guardPhi.addInput(firstIf.trueSuccessor());
guardPhi.addInput(secondIf.trueSuccessor());
}
return guardPhi;
}
private static boolean doubleEquals(double a, double b) {
assert !Double.isNaN(a) && !Double.isNaN(b) && !Double.isInfinite(a) && !Double.isInfinite(b);
return a - EPSILON < b && a + EPSILON > b;
}
private static double sanitizeProbability(double value) {
double newValue = Math.min(1.0, Math.max(0.0, value));
if (Double.isNaN(newValue)) {
newValue = 0.5;
}
return newValue;
}
@SuppressWarnings("try")
private static void processConditional(LogicNode x, boolean xNegated, LogicNode y, boolean yNegated, ConditionalNode conditional) {
try (DebugCloseable context = conditional.withNodeSourcePosition()) {
ValueNode trueTarget = conditional.trueValue();
ValueNode falseTarget = conditional.falseValue();
Graph graph = conditional.graph();
ConditionalNode secondConditional = graph.unique(new ConditionalNode(y, yNegated ? falseTarget : trueTarget, yNegated ? trueTarget : falseTarget));
ConditionalNode firstConditional = graph.unique(new ConditionalNode(x, xNegated ? secondConditional : trueTarget, xNegated ? trueTarget : secondConditional));
conditional.replaceAndDelete(firstConditional);
graph.getDebug().dump(DebugContext.VERY_DETAILED_LEVEL, graph, "After processing conditional %s", conditional);
}
}
@Override
public boolean checkContract() {
return false;
}
}
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