/* * Copyright (c) 2012, 2019, 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. * * 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. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ package org.graalvm.compiler.nodes.extended; import static org.graalvm.compiler.nodeinfo.NodeCycles.CYCLES_0; import static org.graalvm.compiler.nodeinfo.NodeSize.SIZE_0; import jdk.vm.ci.meta.JavaKind; import org.graalvm.compiler.core.common.calc.CanonicalCondition; import org.graalvm.compiler.core.common.type.IntegerStamp; import org.graalvm.compiler.core.common.type.StampFactory; import org.graalvm.compiler.debug.GraalError; import org.graalvm.compiler.graph.Node; import org.graalvm.compiler.graph.NodeClass; import org.graalvm.compiler.graph.iterators.NodePredicates; import org.graalvm.compiler.graph.spi.Canonicalizable; import org.graalvm.compiler.graph.spi.CanonicalizerTool; import org.graalvm.compiler.graph.spi.Simplifiable; import org.graalvm.compiler.graph.spi.SimplifierTool; import org.graalvm.compiler.nodeinfo.NodeInfo; import org.graalvm.compiler.nodes.FixedGuardNode; import org.graalvm.compiler.nodes.IfNode; import org.graalvm.compiler.nodes.NodeView; import org.graalvm.compiler.nodes.ReturnNode; import org.graalvm.compiler.nodes.ValueNode; import org.graalvm.compiler.nodes.calc.ConditionalNode; import org.graalvm.compiler.nodes.calc.FloatingNode; import org.graalvm.compiler.nodes.calc.IntegerEqualsNode; import org.graalvm.compiler.nodes.calc.NarrowNode; import org.graalvm.compiler.nodes.calc.ZeroExtendNode; import org.graalvm.compiler.nodes.spi.Lowerable; import org.graalvm.compiler.nodes.spi.LoweringTool; /** * Instances of this node class will look for a preceding if node and put the given probability into * the if node's taken probability. Then the branch probability node will be removed. This node is * intended primarily for snippets, so that they can define their fast and slow paths. */ @NodeInfo(cycles = CYCLES_0, cyclesRationale = "Artificial Node", size = SIZE_0) public final class BranchProbabilityNode extends FloatingNode implements Simplifiable, Lowerable, Canonicalizable { public static final NodeClass TYPE = NodeClass.create(BranchProbabilityNode.class); public static final double LIKELY_PROBABILITY = 0.6; public static final double NOT_LIKELY_PROBABILITY = 1 - LIKELY_PROBABILITY; public static final double FREQUENT_PROBABILITY = 0.9; public static final double NOT_FREQUENT_PROBABILITY = 1 - FREQUENT_PROBABILITY; public static final double FAST_PATH_PROBABILITY = 0.99; public static final double SLOW_PATH_PROBABILITY = 1 - FAST_PATH_PROBABILITY; public static final double VERY_FAST_PATH_PROBABILITY = 0.999; public static final double VERY_SLOW_PATH_PROBABILITY = 1 - VERY_FAST_PATH_PROBABILITY; public static final double DEOPT_PROBABILITY = 0.0; /* * This probability may seem excessive, but it makes a difference in long running loops. Lets * say a loop is executed 100k times and it has a few null checks with probability 0.999. As * these probabilities multiply for every loop iteration, the overall loop frequency will be * calculated as approximately 30 while it should be 100k. */ public static final double LUDICROUSLY_FAST_PATH_PROBABILITY = 0.999999; public static final double LUDICROUSLY_SLOW_PATH_PROBABILITY = 1 - LUDICROUSLY_FAST_PATH_PROBABILITY; @Input ValueNode probability; @Input ValueNode condition; public BranchProbabilityNode(ValueNode probability, ValueNode condition) { super(TYPE, StampFactory.forKind(JavaKind.Boolean)); this.probability = probability; this.condition = condition; } public ValueNode getProbability() { return probability; } public ValueNode getCondition() { return condition; } @Override public Node canonical(CanonicalizerTool tool) { if (condition.isConstant()) { // fold constant conditions early during PE return condition; } return this; } @Override public void simplify(SimplifierTool tool) { if (!hasUsages()) { return; } if (probability.isConstant()) { double probabilityValue = probability.asJavaConstant().asDouble(); if (probabilityValue < 0.0) { throw new GraalError("A negative probability of " + probabilityValue + " is not allowed!"); } else if (probabilityValue > 1.0) { throw new GraalError("A probability of more than 1.0 (" + probabilityValue + ") is not allowed!"); } else if (Double.isNaN(probabilityValue)) { /* * We allow NaN if the node is in unreachable code that will eventually fall away, * or else an error will be thrown during lowering since we keep the node around. */ return; } boolean usageFound = false; for (IntegerEqualsNode node : this.usages().filter(IntegerEqualsNode.class)) { assert node.condition() == CanonicalCondition.EQ; ValueNode other = node.getX(); if (node.getX() == this) { other = node.getY(); } if (other.isConstant()) { double probabilityToSet = probabilityValue; if (other.asJavaConstant().asInt() == 0) { probabilityToSet = 1.0 - probabilityToSet; } for (IfNode ifNodeUsages : node.usages().filter(IfNode.class)) { usageFound = true; ifNodeUsages.setTrueSuccessorProbability(probabilityToSet); } if (!usageFound) { usageFound = node.usages().filter(NodePredicates.isA(FixedGuardNode.class).or(ConditionalNode.class)).isNotEmpty(); } } } if (usageFound) { ValueNode currentCondition = condition; IntegerStamp currentStamp = (IntegerStamp) currentCondition.stamp(NodeView.DEFAULT); if (currentStamp.lowerBound() < 0 || 1 < currentStamp.upperBound()) { ValueNode narrow = graph().maybeAddOrUnique(NarrowNode.create(currentCondition, 1, NodeView.DEFAULT)); currentCondition = graph().maybeAddOrUnique(ZeroExtendNode.create(narrow, 32, NodeView.DEFAULT)); } replaceAndDelete(currentCondition); if (tool != null) { tool.addToWorkList(currentCondition.usages()); } } else { if (!isSubstitutionGraph()) { throw new GraalError("Wrong usage of branch probability injection!"); } } } } private boolean isSubstitutionGraph() { return hasExactlyOneUsage() && usages().first() instanceof ReturnNode; } /** * This intrinsic should only be used for the condition of an if statement. The parameter * condition should also only denote a simple condition and not a combined condition involving * && or || operators. It injects the probability of the condition into the if * statement. * * @param probability the probability that the given condition is true as a double value between * 0.0 and 1.0. * @param condition the simple condition without any && or || operators * @return the condition */ @NodeIntrinsic public static native boolean probability(double probability, boolean condition); @Override public void lower(LoweringTool tool) { throw new GraalError("Branch probability could not be injected, because the probability value did not reduce to a constant value."); } }