hotspot/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.replacements/src/org/graalvm/compiler/replacements/nodes/BitCountNode.java

/*
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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.
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package org.graalvm.compiler.replacements.nodes;

import static org.graalvm.compiler.nodeinfo.NodeCycles.CYCLES_3;
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.core.common.type.StampFactory;
import org.graalvm.compiler.graph.NodeClass;
import org.graalvm.compiler.graph.spi.CanonicalizerTool;
import org.graalvm.compiler.lir.gen.ArithmeticLIRGeneratorTool;
import org.graalvm.compiler.nodeinfo.NodeInfo;
import org.graalvm.compiler.nodes.ConstantNode;
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 jdk.vm.ci.code.CodeUtil;
import jdk.vm.ci.meta.JavaConstant;
import jdk.vm.ci.meta.JavaKind;

@NodeInfo(cycles = CYCLES_3, size = SIZE_1)
public final class BitCountNode extends UnaryNode implements ArithmeticLIRLowerable {

    public static final NodeClass<BitCountNode> TYPE = NodeClass.create(BitCountNode.class);

    public BitCountNode(ValueNode value) {
        super(TYPE, computeStamp(value.stamp(), value), value);
        assert value.getStackKind() == JavaKind.Int || value.getStackKind() == JavaKind.Long;
    }

    @Override
    public Stamp foldStamp(Stamp newStamp) {
        ValueNode theValue = getValue();
        return computeStamp(newStamp, theValue);
    }

    static Stamp computeStamp(Stamp newStamp, ValueNode theValue) {
        assert newStamp.isCompatible(theValue.stamp());
        IntegerStamp valueStamp = (IntegerStamp) newStamp;
        assert (valueStamp.downMask() & CodeUtil.mask(valueStamp.getBits())) == valueStamp.downMask();
        assert (valueStamp.upMask() & CodeUtil.mask(valueStamp.getBits())) == valueStamp.upMask();
        return StampFactory.forInteger(JavaKind.Int, Long.bitCount(valueStamp.downMask()), Long.bitCount(valueStamp.upMask()));
    }

    @Override
    public ValueNode canonical(CanonicalizerTool tool, ValueNode forValue) {
        if (forValue.isConstant()) {
            JavaConstant c = forValue.asJavaConstant();
            return ConstantNode.forInt(forValue.getStackKind() == JavaKind.Int ? Integer.bitCount(c.asInt()) : Long.bitCount(c.asLong()));
        }
        return this;
    }

    @Override
    public void generate(NodeLIRBuilderTool builder, ArithmeticLIRGeneratorTool gen) {
        builder.setResult(this, gen.emitBitCount(builder.operand(getValue())));
    }
}