/*

 * Copyright (c) 2015, 2019, Oracle and/or its affiliates. All rights reserved.

 * 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.core.phases;

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

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

import org.graalvm.compiler.debug.DebugContext;

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

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

import org.graalvm.compiler.graph.Node;

import org.graalvm.compiler.nodes.LogicConstantNode;

import org.graalvm.compiler.nodes.StructuredGraph;

import org.graalvm.compiler.nodes.spi.CoreProviders;

import org.graalvm.compiler.phases.BasePhase;

import org.graalvm.compiler.phases.PhaseSuite;

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

/**

 * A utility phase for detecting when a phase would change the graph and reporting extra information

 * about the effects. The phase is first run on a copy of the graph and if a change in that graph is

 * detected then it's rerun on the original graph inside a new debug scope under

 * GraphChangeMonitoringPhase. The message argument can be used to distinguish between the same

 * phase run at different points.

 *

 * @param <C>

 */

public class GraphChangeMonitoringPhase<C extends CoreProviders> extends PhaseSuite<C> {

    private final String message;

    public GraphChangeMonitoringPhase(String message, BasePhase<C> phase) {

        super();

        this.message = message;

        appendPhase(phase);

    }

    public GraphChangeMonitoringPhase(String message) {

        super();

        this.message = message;

    }

    @Override

    @SuppressWarnings("try")

    protected void run(StructuredGraph graph, C context) {

        /*

         * Phase may add nodes but not end up using them so ignore additions. Nodes going dead and

         * having their inputs change are the main interesting differences.

         */

        EconomicSetNodeEventListener listener = new EconomicSetNodeEventListener().exclude(NodeEvent.NODE_ADDED);

        StructuredGraph graphCopy = (StructuredGraph) graph.copy(graph.getDebug());

        DebugContext debug = graph.getDebug();

        try (NodeEventScope s = graphCopy.trackNodeEvents(listener)) {

            try (DebugContext.Scope s2 = debug.sandbox("WithoutMonitoring", null)) {

                super.run(graphCopy, context);

            } catch (Throwable t) {

                debug.handle(t);

            }

        }

        EconomicSet<Node> filteredNodes = EconomicSet.create(Equivalence.IDENTITY);

        for (Node n : listener.getNodes()) {

            if (n instanceof LogicConstantNode) {

                // Ignore LogicConstantNode since those are sometimes created and deleted as part of

                // running a phase.

            } else {

                filteredNodes.add(n);

            }

        }

        if (!filteredNodes.isEmpty()) {

            /* rerun it on the real graph in a new Debug scope so Dump and Log can find it. */

            listener = new EconomicSetNodeEventListener();

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

                try (DebugContext.Scope s2 = debug.scope("WithGraphChangeMonitoring")) {

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

                        debug.dump(DebugContext.DETAILED_LEVEL, graph, "*** Before phase %s", getName());

                    }

                    super.run(graph, context);

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

                        debug.dump(DebugContext.DETAILED_LEVEL, graph, "*** After phase %s %s", getName(), filteredNodes);

                    }

                    debug.log("*** %s %s %s\n", message, graph, filteredNodes);

                }

            }

        } else {

            // Go ahead and run it normally even though it should have no effect

            super.run(graph, context);

        }

    }

}