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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.hotspot.nodes.profiling;

import static org.graalvm.compiler.nodeinfo.NodeCycles.CYCLES_IGNORED;
import static org.graalvm.compiler.nodeinfo.NodeSize.SIZE_IGNORED;
import static org.graalvm.compiler.nodes.util.GraphUtil.removeFixedWithUnusedInputs;

import org.graalvm.compiler.core.common.type.StampFactory;
import org.graalvm.compiler.graph.Node;
import org.graalvm.compiler.graph.NodeClass;
import org.graalvm.compiler.graph.iterators.NodeIterable;
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.AbstractMergeNode;
import org.graalvm.compiler.nodes.ControlSplitNode;
import org.graalvm.compiler.nodes.DeoptimizingFixedWithNextNode;
import org.graalvm.compiler.nodes.StructuredGraph;
import org.graalvm.compiler.nodes.ValueNode;
import org.graalvm.compiler.nodes.spi.Lowerable;
import org.graalvm.compiler.nodes.spi.LoweringTool;
import org.graalvm.compiler.options.Option;
import org.graalvm.compiler.options.OptionKey;
import org.graalvm.compiler.options.OptionType;

import jdk.vm.ci.meta.ResolvedJavaMethod;

@NodeInfo(cycles = CYCLES_IGNORED, cyclesRationale = "profiling should be ignored", size = SIZE_IGNORED, sizeRationale = "profiling should be ignored")
public abstract class ProfileNode extends DeoptimizingFixedWithNextNode implements Simplifiable, Lowerable {
    public static class Options {
        @Option(help = "Control probabilistic profiling on AMD64", type = OptionType.Expert)//
        public static final OptionKey<Boolean> ProbabilisticProfiling = new OptionKey<>(true);
    }

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

    protected ResolvedJavaMethod method;

    // Only used if ProbabilisticProfiling == true and may be ignored by lowerer.
    @OptionalInput protected ValueNode random;

    // Logarithm base 2 of the profile probability.
    protected int probabilityLog;

    // Step value to add to the profile counter.
    protected int step;

    protected ProfileNode(NodeClass<? extends DeoptimizingFixedWithNextNode> c, ResolvedJavaMethod method, int probabilityLog) {
        super(c, StampFactory.forVoid());
        this.method = method;
        this.probabilityLog = probabilityLog;
        this.step = 1;
    }

    public ProfileNode(ResolvedJavaMethod method, int probabilityLog) {
        this(TYPE, method, probabilityLog);
    }

    @Override
    public boolean canDeoptimize() {
        return true;
    }

    @Override
    public void lower(LoweringTool tool) {
        tool.getLowerer().lower(this, tool);
    }

    public ResolvedJavaMethod getProfiledMethod() {
        return method;
    }

    public ValueNode getRandom() {
        return random;
    }

    public void setRandom(ValueNode r) {
        updateUsages(random, r);
        this.random = r;
    }

    public int getStep() {
        return step;
    }

    public void setStep(int s) {
        step = s;
    }

    
Get the logarithm base 2 of the profile probability.
/**
     * Get the logarithm base 2 of the profile probability.
     */
    public int getProbabilityLog() {
        return probabilityLog;
    }

    
Gathers all the ProfileNodes that are inputs to the live nodes in a given graph. /**
     * Gathers all the {@link ProfileNode}s that are inputs to the
     * {@linkplain StructuredGraph#getNodes() live nodes} in a given graph.
     */
    public static NodeIterable<ProfileNode> getProfileNodes(StructuredGraph graph) {
        return graph.getNodes().filter(ProfileNode.class);
    }

    protected abstract boolean canBeMergedWith(ProfileNode p);

    @Override
    public void simplify(SimplifierTool tool) {
        for (Node p = predecessor(); p != null; p = p.predecessor()) {
            // Terminate search when we hit a control split or merge.
            if (p instanceof ControlSplitNode || p instanceof AbstractMergeNode) {
                break;
            }
            if (p instanceof ProfileNode) {
                ProfileNode that = (ProfileNode) p;
                if (this.canBeMergedWith(that)) {
                    that.setStep(this.getStep() + that.getStep());
                    removeFixedWithUnusedInputs(this);
                    tool.addToWorkList(that);
                    break;
                }
            }
        }
    }
}