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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

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package org.graalvm.compiler.virtual.phases.ea;

import static org.graalvm.compiler.phases.common.DeadCodeEliminationPhase.Optionality.Required;

import jdk.internal.vm.compiler.collections.EconomicSet;

import org.graalvm.compiler.core.common.util.CompilationAlarm;

import org.graalvm.compiler.debug.DebugContext;

import org.graalvm.compiler.graph.Graph.NodeEventScope;

import org.graalvm.compiler.graph.Node;

import org.graalvm.compiler.graph.spi.Simplifiable;

import org.graalvm.compiler.nodes.StructuredGraph;

import org.graalvm.compiler.nodes.StructuredGraph.ScheduleResult;

import org.graalvm.compiler.nodes.cfg.ControlFlowGraph;

import org.graalvm.compiler.phases.BasePhase;

import org.graalvm.compiler.phases.common.CanonicalizerPhase;

import org.graalvm.compiler.phases.common.DeadCodeEliminationPhase;

import org.graalvm.compiler.phases.common.util.EconomicSetNodeEventListener;

import org.graalvm.compiler.phases.graph.ReentrantBlockIterator;

import org.graalvm.compiler.phases.schedule.SchedulePhase;

import org.graalvm.compiler.phases.tiers.PhaseContext;

public abstract class EffectsPhase<PhaseContextT extends PhaseContext> extends BasePhase<PhaseContextT> {

    public abstract static class Closure<T> extends ReentrantBlockIterator.BlockIteratorClosure<T> {

        public abstract boolean hasChanged();

        public abstract boolean needsApplyEffects();

        public abstract void applyEffects();

    }

    private final int maxIterations;

    protected final CanonicalizerPhase canonicalizer;

    private final boolean unscheduled;

    protected EffectsPhase(int maxIterations, CanonicalizerPhase canonicalizer) {

        this(maxIterations, canonicalizer, false);

    }

    protected EffectsPhase(int maxIterations, CanonicalizerPhase canonicalizer, boolean unscheduled) {

        this.maxIterations = maxIterations;

        this.canonicalizer = canonicalizer;

        this.unscheduled = unscheduled;

    }

    @Override

    protected void run(StructuredGraph graph, PhaseContextT context) {

        runAnalysis(graph, context);

    }

    @SuppressWarnings("try")

    public boolean runAnalysis(StructuredGraph graph, PhaseContextT context) {

        boolean changed = false;

        CompilationAlarm compilationAlarm = CompilationAlarm.current();

        DebugContext debug = graph.getDebug();

        for (int iteration = 0; iteration < maxIterations && !compilationAlarm.hasExpired(); iteration++) {

            try (DebugContext.Scope s = debug.scope(debug.areScopesEnabled() ? "iteration " + iteration : null)) {

                ScheduleResult schedule;

                ControlFlowGraph cfg;

                if (unscheduled) {

                    schedule = null;

                    cfg = ControlFlowGraph.compute(graph, true, true, false, false);

                } else {

                    new SchedulePhase(SchedulePhase.SchedulingStrategy.EARLIEST).apply(graph, false);

                    schedule = graph.getLastSchedule();

                    cfg = schedule.getCFG();

                }

                try (DebugContext.Scope scheduleScope = debug.scope("EffectsPhaseWithSchedule", schedule)) {

                    Closure<?> closure = createEffectsClosure(context, schedule, cfg);

                    ReentrantBlockIterator.apply(closure, cfg.getStartBlock());

                    if (closure.needsApplyEffects()) {

                        // apply the effects collected during this iteration

                        EconomicSetNodeEventListener listener = new EconomicSetNodeEventListener();

                        try (NodeEventScope nes = graph.trackNodeEvents(listener)) {

                            closure.applyEffects();

                        }

                        if (debug.isDumpEnabled(DebugContext.VERBOSE_LEVEL)) {

                            debug.dump(DebugContext.VERBOSE_LEVEL, graph, "%s iteration", getName());

                        }

                        new DeadCodeEliminationPhase(Required).apply(graph);

                        EconomicSet<Node> changedNodes = listener.getNodes();

                        for (Node node : graph.getNodes()) {

                            if (node instanceof Simplifiable) {

                                changedNodes.add(node);

                            }

                        }

                        postIteration(graph, context, changedNodes);

                    }

                    if (closure.hasChanged()) {

                        changed = true;

                    } else {

                        break;

                    }

                } catch (Throwable t) {

                    throw debug.handle(t);

                }

            }

        }

        return changed;

    }

    protected void postIteration(final StructuredGraph graph, final PhaseContextT context, EconomicSet<Node> changedNodes) {

        if (canonicalizer != null) {

            canonicalizer.applyIncremental(graph, context, changedNodes);

        }

    }

    protected abstract Closure<?> createEffectsClosure(PhaseContextT context, ScheduleResult schedule, ControlFlowGraph cfg);

}