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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * 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).
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 * 2 along with this work; if not, write to the Free Software Foundation,
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package org.graalvm.compiler.replacements.amd64;

import static org.graalvm.compiler.nodeinfo.NodeCycles.CYCLES_2;
import static org.graalvm.compiler.nodeinfo.NodeSize.SIZE_1;

import org.graalvm.compiler.core.common.type.IntegerStamp;
import org.graalvm.compiler.core.common.type.Stamp;
import org.graalvm.compiler.graph.NodeClass;
import org.graalvm.compiler.graph.spi.CanonicalizerTool;
import org.graalvm.compiler.lir.amd64.AMD64ArithmeticLIRGeneratorTool;
import org.graalvm.compiler.lir.gen.ArithmeticLIRGeneratorTool;
import org.graalvm.compiler.nodeinfo.NodeInfo;
import org.graalvm.compiler.nodes.ConstantNode;
import org.graalvm.compiler.nodes.NodeView;
import org.graalvm.compiler.nodes.ValueNode;
import org.graalvm.compiler.nodes.calc.UnaryNode;
import org.graalvm.compiler.nodes.spi.ArithmeticLIRLowerable;
import org.graalvm.compiler.nodes.spi.NodeLIRBuilderTool;
import org.graalvm.compiler.nodes.type.StampTool;

import jdk.vm.ci.meta.JavaConstant;
import jdk.vm.ci.meta.JavaKind;

Count the number of leading zeros using the lzcntq or lzcntl instructions.
/** * Count the number of leading zeros using the {@code lzcntq} or {@code lzcntl} instructions. */
@NodeInfo(cycles = CYCLES_2, size = SIZE_1) public final class AMD64CountLeadingZerosNode extends UnaryNode implements ArithmeticLIRLowerable { public static final NodeClass<AMD64CountLeadingZerosNode> TYPE = NodeClass.create(AMD64CountLeadingZerosNode.class); public AMD64CountLeadingZerosNode(ValueNode value) { super(TYPE, computeStamp(value.stamp(NodeView.DEFAULT), value), value); assert value.getStackKind() == JavaKind.Int || value.getStackKind() == JavaKind.Long; } @Override public Stamp foldStamp(Stamp newStamp) { return computeStamp(newStamp, getValue()); } private static Stamp computeStamp(Stamp newStamp, ValueNode theValue) { assert newStamp.isCompatible(theValue.stamp(NodeView.DEFAULT)); assert theValue.getStackKind() == JavaKind.Int || theValue.getStackKind() == JavaKind.Long; return StampTool.stampForLeadingZeros((IntegerStamp) newStamp); } public static ValueNode tryFold(ValueNode value) { if (value.isConstant()) { JavaConstant c = value.asJavaConstant(); if (value.getStackKind() == JavaKind.Int) { return ConstantNode.forInt(Integer.numberOfLeadingZeros(c.asInt())); } else { return ConstantNode.forInt(Long.numberOfLeadingZeros(c.asLong())); } } return null; } @Override public ValueNode canonical(CanonicalizerTool tool, ValueNode forValue) { ValueNode folded = tryFold(forValue); return folded != null ? folded : this; } @Override public void generate(NodeLIRBuilderTool builder, ArithmeticLIRGeneratorTool gen) { builder.setResult(this, ((AMD64ArithmeticLIRGeneratorTool) gen).emitCountLeadingZeros(builder.operand(getValue()))); } }