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package org.graalvm.compiler.phases.common.inlining.walker;

import java.util.BitSet;
import java.util.LinkedList;
import java.util.function.ToDoubleFunction;

import jdk.internal.vm.compiler.collections.EconomicSet;
import jdk.internal.vm.compiler.collections.Equivalence;
import org.graalvm.compiler.nodes.FixedNode;
import org.graalvm.compiler.nodes.Invoke;
import org.graalvm.compiler.nodes.ParameterNode;
import org.graalvm.compiler.nodes.StructuredGraph;
import org.graalvm.compiler.nodes.ValueNode;
import org.graalvm.compiler.phases.common.inlining.policy.AbstractInliningPolicy;
import org.graalvm.compiler.phases.graph.FixedNodeRelativeFrequencyCache;

import jdk.vm.ci.meta.ResolvedJavaMethod;

 A CallsiteHolder whose graph has been copied already and thus can be modified without affecting the original (usually cached) version. 
 An instance of this class is derived from an InlineableGraph and contains a subset of the information there: just the Invoke nodes from it. Such nodes are candidates for depth-first search of further inlining opportunities (thus the adjective "explorable" given to this class) 
See Also:
InliningData.moveForward()/**
 * <p>
 * A {@link CallsiteHolder} whose graph has been copied already and thus can be modified without
 * affecting the original (usually cached) version.
 * </p>
 *
 * <p>
 * An instance of this class is derived from an
 * {@link org.graalvm.compiler.phases.common.inlining.info.elem.InlineableGraph InlineableGraph} and
 * contains a subset of the information there: just the {@link Invoke} nodes from it. Such nodes are
 * candidates for depth-first search of further inlining opportunities (thus the adjective
 * "explorable" given to this class)
 * </p>
 *
 * @see InliningData#moveForward()
 */
public final class CallsiteHolderExplorable extends CallsiteHolder {

    
Graph in which inlining may be performed at one or more of the callsites containined in remainingInvokes. /**
     * Graph in which inlining may be performed at one or more of the callsites containined in
     * {@link #remainingInvokes}.
     */
    private final StructuredGraph graph;

    private final LinkedList<Invoke> remainingInvokes;
    private final double probability;
    private final double relevance;

    
See Also:
getFixedParams()/**
     * @see #getFixedParams()
     */
    private final EconomicSet<ParameterNode> fixedParams;

    private final ToDoubleFunction<FixedNode> probabilities;
    private final ComputeInliningRelevance computeInliningRelevance;

    public CallsiteHolderExplorable(StructuredGraph graph, double probability, double relevance, BitSet freshlyInstantiatedArguments, LinkedList<Invoke> invokes) {
        assert graph != null;
        this.graph = graph;
        this.probability = probability;
        this.relevance = relevance;
        this.fixedParams = fixedParamsAt(freshlyInstantiatedArguments);
        remainingInvokes = invokes == null ? new InliningIterator(graph).apply() : invokes;
        if (remainingInvokes.isEmpty()) {
            probabilities = null;
            computeInliningRelevance = null;
        } else {
            probabilities = new FixedNodeRelativeFrequencyCache();
            computeInliningRelevance = new ComputeInliningRelevance(graph, probabilities);
            computeProbabilities();
        }
        assert repOK();
    }

    
See Also:
getFixedParams()/**
     * @see #getFixedParams()
     */
    private EconomicSet<ParameterNode> fixedParamsAt(BitSet freshlyInstantiatedArguments) {
        if (freshlyInstantiatedArguments == null || freshlyInstantiatedArguments.isEmpty()) {
            return EconomicSet.create(Equivalence.IDENTITY);
        }
        EconomicSet<ParameterNode> result = EconomicSet.create(Equivalence.IDENTITY);
        for (ParameterNode p : graph.getNodes(ParameterNode.TYPE)) {
            if (freshlyInstantiatedArguments.get(p.index())) {
                result.add(p);
            }
        }
        return result;
    }

    
 Parameters for which the callsite targeting graph() provides "fixed" arguments. That callsite isn't referenced by this instance. Instead, it belongs to the graph of the caller of this CallsiteHolderExplorable 
 Constant arguments don't contribute to fixed-params: those params have been removed already, see InlineableGraph. 

Instead, fixed-params are those receiving freshly instantiated arguments (possibly
instantiated several levels up in the call-hierarchy)

/**
     * <p>
     * Parameters for which the callsite targeting {@link #graph()} provides "fixed" arguments. That
     * callsite isn't referenced by this instance. Instead, it belongs to the graph of the caller of
     * this {@link CallsiteHolderExplorable}
     * </p>
     *
     * <p>
     * Constant arguments don't contribute to fixed-params: those params have been removed already,
     * see {@link org.graalvm.compiler.phases.common.inlining.info.elem.InlineableGraph}.
     * </p>
     *
     * <p>
     * Instead, fixed-params are those receiving freshly instantiated arguments (possibly
     * instantiated several levels up in the call-hierarchy)
     * </p>
     */
    public EconomicSet<ParameterNode> getFixedParams() {
        return fixedParams;
    }

    public boolean repOK() {
        for (Invoke invoke : remainingInvokes) {
            if (!invoke.asNode().isAlive() || !containsInvoke(invoke)) {
                assert false;
                return false;
            }
            if (!allArgsNonNull(invoke)) {
                assert false;
                return false;
            }
        }
        for (ParameterNode fixedParam : fixedParams) {
            if (!containsParam(fixedParam)) {
                assert false;
                return false;
            }
        }
        return true;
    }

    @Override
    public ResolvedJavaMethod method() {
        return graph == null ? null : graph.method();
    }

    @Override
    public boolean hasRemainingInvokes() {
        return !remainingInvokes.isEmpty();
    }

    @Override
    public StructuredGraph graph() {
        return graph;
    }

    public Invoke popInvoke() {
        return remainingInvokes.removeFirst();
    }

    public void pushInvoke(Invoke invoke) {
        remainingInvokes.push(invoke);
    }

    public static boolean allArgsNonNull(Invoke invoke) {
        for (ValueNode arg : invoke.callTarget().arguments()) {
            if (arg == null) {
                assert false;
                return false;
            }
        }
        return true;
    }

    public boolean containsInvoke(Invoke invoke) {
        for (Invoke i : graph().getInvokes()) {
            if (i == invoke) {
                return true;
            }
        }
        return false;
    }

    public boolean containsParam(ParameterNode param) {
        for (ParameterNode p : graph.getNodes(ParameterNode.TYPE)) {
            if (p == param) {
                return true;
            }
        }
        return false;
    }

    public void computeProbabilities() {
        computeInliningRelevance.compute();
    }

    public double invokeProbability(Invoke invoke) {
        return probability * probabilities.applyAsDouble(invoke.asNode());
    }

    public double invokeRelevance(Invoke invoke) {
        return Math.min(AbstractInliningPolicy.CapInheritedRelevance, relevance) * computeInliningRelevance.getRelevance(invoke);
    }

    @Override
    public String toString() {
        return (graph != null ? method().format("%H.%n(%p)") : "<null method>") + remainingInvokes;
    }
}