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 * 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

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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 {@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())));

    }

}