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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * This code is free software; you can redistribute it and/or modify it
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 * published by the Free Software Foundation.
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 * 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.nodes.calc;

import static org.graalvm.compiler.nodeinfo.NodeCycles.CYCLES_0;
import static org.graalvm.compiler.nodeinfo.NodeSize.SIZE_2;
import static org.graalvm.compiler.nodes.calc.CompareNode.createCompareNode;

import org.graalvm.compiler.core.common.calc.Condition;
import org.graalvm.compiler.core.common.type.IntegerStamp;
import org.graalvm.compiler.core.common.type.Stamp;
import org.graalvm.compiler.core.common.type.StampFactory;
import org.graalvm.compiler.graph.NodeClass;
import org.graalvm.compiler.graph.spi.Canonicalizable;
import org.graalvm.compiler.graph.spi.CanonicalizerTool;
import org.graalvm.compiler.nodeinfo.InputType;
import org.graalvm.compiler.nodeinfo.NodeInfo;
import org.graalvm.compiler.nodes.ConstantNode;
import org.graalvm.compiler.nodes.LogicConstantNode;
import org.graalvm.compiler.nodes.LogicNegationNode;
import org.graalvm.compiler.nodes.LogicNode;
import org.graalvm.compiler.nodes.StructuredGraph;
import org.graalvm.compiler.nodes.ValueNode;
import org.graalvm.compiler.nodes.spi.LIRLowerable;
import org.graalvm.compiler.nodes.spi.NodeLIRBuilderTool;

import jdk.vm.ci.meta.JavaConstant;

The ConditionalNode class represents a comparison that yields one of two values. Note that these nodes are not built directly from the bytecode but are introduced by canonicalization.
/** * The {@code ConditionalNode} class represents a comparison that yields one of two values. Note * that these nodes are not built directly from the bytecode but are introduced by canonicalization. */
@NodeInfo(cycles = CYCLES_0, size = SIZE_2) public final class ConditionalNode extends FloatingNode implements Canonicalizable, LIRLowerable { public static final NodeClass<ConditionalNode> TYPE = NodeClass.create(ConditionalNode.class); @Input(InputType.Condition) LogicNode condition; @Input ValueNode trueValue; @Input ValueNode falseValue; public LogicNode condition() { return condition; } public ConditionalNode(LogicNode condition) { this(condition, ConstantNode.forInt(1, condition.graph()), ConstantNode.forInt(0, condition.graph())); } public ConditionalNode(LogicNode condition, ValueNode trueValue, ValueNode falseValue) { super(TYPE, trueValue.stamp().meet(falseValue.stamp())); assert trueValue.stamp().isCompatible(falseValue.stamp()); this.condition = condition; this.trueValue = trueValue; this.falseValue = falseValue; } public static ValueNode create(LogicNode condition) { return create(condition, ConstantNode.forInt(1, condition.graph()), ConstantNode.forInt(0, condition.graph())); } public static ValueNode create(LogicNode condition, ValueNode trueValue, ValueNode falseValue) { ValueNode synonym = findSynonym(condition, trueValue, falseValue); if (synonym != null) { return synonym; } return new ConditionalNode(condition, trueValue, falseValue); } @Override public boolean inferStamp() { Stamp valueStamp = trueValue.stamp().meet(falseValue.stamp()); if (condition instanceof IntegerLessThanNode) { IntegerLessThanNode lessThan = (IntegerLessThanNode) condition; if (lessThan.getX() == trueValue && lessThan.getY() == falseValue) { // this encodes a min operation JavaConstant constant = lessThan.getX().asJavaConstant(); if (constant == null) { constant = lessThan.getY().asJavaConstant(); } if (constant != null) { IntegerStamp bounds = StampFactory.forInteger(constant.getJavaKind(), constant.getJavaKind().getMinValue(), constant.asLong()); valueStamp = valueStamp.join(bounds); } } else if (lessThan.getX() == falseValue && lessThan.getY() == trueValue) { // this encodes a max operation JavaConstant constant = lessThan.getX().asJavaConstant(); if (constant == null) { constant = lessThan.getY().asJavaConstant(); } if (constant != null) { IntegerStamp bounds = StampFactory.forInteger(constant.getJavaKind(), constant.asLong(), constant.getJavaKind().getMaxValue()); valueStamp = valueStamp.join(bounds); } } } return updateStamp(valueStamp); } public ValueNode trueValue() { return trueValue; } public ValueNode falseValue() { return falseValue; } @Override public ValueNode canonical(CanonicalizerTool tool) { ValueNode synonym = findSynonym(condition, trueValue(), falseValue()); if (synonym != null) { return synonym; } ValueNode result = canonicalizeConditional(condition, trueValue(), falseValue(), stamp); if (result != null) { return result; } return this; } public static ValueNode canonicalizeConditional(LogicNode condition, ValueNode trueValue, ValueNode falseValue, Stamp stamp) { // this optimizes the case where a value that can only be 0 or 1 is materialized to 0 or 1 if (trueValue.isConstant() && falseValue.isConstant() && condition instanceof IntegerEqualsNode) { IntegerEqualsNode equals = (IntegerEqualsNode) condition; if (equals.getY().isConstant() && equals.getY().asConstant().equals(JavaConstant.INT_0) && equals.getX().stamp() instanceof IntegerStamp) { IntegerStamp equalsXStamp = (IntegerStamp) equals.getX().stamp(); if (equalsXStamp.upMask() == 1) { if (trueValue.asConstant().equals(JavaConstant.INT_0) && falseValue.asConstant().equals(JavaConstant.INT_1)) { return IntegerConvertNode.convertUnsigned(equals.getX(), stamp); } } } } if (condition instanceof CompareNode && ((CompareNode) condition).isIdentityComparison()) { // optimize the pattern (x == y) ? x : y CompareNode compare = (CompareNode) condition; if ((compare.getX() == trueValue && compare.getY() == falseValue) || (compare.getX() == falseValue && compare.getY() == trueValue)) { return falseValue; } } if (trueValue == falseValue) { return trueValue; } if (condition instanceof IntegerLessThanNode && trueValue.stamp() instanceof IntegerStamp) { /* * Convert a conditional add ((x < 0) ? (x + y) : x) into (x + (y & (x >> (bits - 1)))) * to avoid the test. */ IntegerLessThanNode lt = (IntegerLessThanNode) condition; if (lt.getY().isConstant() && lt.getY().asConstant().isDefaultForKind()) { if (falseValue == lt.getX()) { if (trueValue instanceof AddNode) { AddNode add = (AddNode) trueValue; if (add.getX() == falseValue) { int bits = ((IntegerStamp) trueValue.stamp()).getBits(); ValueNode shift = new RightShiftNode(lt.getX(), ConstantNode.forIntegerBits(32, bits - 1)); ValueNode and = new AndNode(shift, add.getY()); return new AddNode(add.getX(), and); } } } } } return null; } private static ValueNode findSynonym(ValueNode condition, ValueNode trueValue, ValueNode falseValue) { if (condition instanceof LogicNegationNode) { LogicNegationNode negated = (LogicNegationNode) condition; return ConditionalNode.create(negated.getValue(), falseValue, trueValue); } if (condition instanceof LogicConstantNode) { LogicConstantNode c = (LogicConstantNode) condition; if (c.getValue()) { return trueValue; } else { return falseValue; } } return null; } @Override public void generate(NodeLIRBuilderTool generator) { generator.emitConditional(this); } public ConditionalNode(StructuredGraph graph, Condition condition, ValueNode x, ValueNode y) { this(createCompareNode(graph, condition, x, y, null)); } }