/*

 * Copyright (c) 2013, 2013, 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

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package org.graalvm.compiler.phases.common;

import java.util.LinkedList;

import java.util.List;

import org.graalvm.compiler.core.common.cfg.Loop;

import org.graalvm.compiler.core.common.type.StampFactory;

import org.graalvm.compiler.nodes.AbstractDeoptimizeNode;

import org.graalvm.compiler.nodes.AbstractMergeNode;

import org.graalvm.compiler.nodes.DynamicDeoptimizeNode;

import org.graalvm.compiler.nodes.EndNode;

import org.graalvm.compiler.nodes.FixedNode;

import org.graalvm.compiler.nodes.FrameState;

import org.graalvm.compiler.nodes.LoopBeginNode;

import org.graalvm.compiler.nodes.LoopExitNode;

import org.graalvm.compiler.nodes.MergeNode;

import org.graalvm.compiler.nodes.PhiNode;

import org.graalvm.compiler.nodes.StructuredGraph;

import org.graalvm.compiler.nodes.ValueNode;

import org.graalvm.compiler.nodes.ValuePhiNode;

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

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

import org.graalvm.compiler.phases.BasePhase;

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

/**

 * This phase tries to find {@link AbstractDeoptimizeNode DeoptimizeNodes} which use the same

 * {@link FrameState} and merges them together.

 */

public class DeoptimizationGroupingPhase extends BasePhase<MidTierContext> {

    @Override

    protected void run(StructuredGraph graph, MidTierContext context) {

        ControlFlowGraph cfg = null;

        for (FrameState fs : graph.getNodes(FrameState.TYPE)) {

            FixedNode target = null;

            PhiNode reasonActionPhi = null;

            PhiNode speculationPhi = null;

            List<AbstractDeoptimizeNode> obsoletes = null;

            for (AbstractDeoptimizeNode deopt : fs.usages().filter(AbstractDeoptimizeNode.class)) {

                if (target == null) {

                    target = deopt;

                } else {

                    if (cfg == null) {

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

                    }

                    AbstractMergeNode merge;

                    if (target instanceof AbstractDeoptimizeNode) {

                        merge = graph.add(new MergeNode());

                        EndNode firstEnd = graph.add(new EndNode());

                        ValueNode actionAndReason = ((AbstractDeoptimizeNode) target).getActionAndReason(context.getMetaAccess());

                        ValueNode speculation = ((AbstractDeoptimizeNode) target).getSpeculation(context.getMetaAccess());

                        reasonActionPhi = graph.addWithoutUnique(new ValuePhiNode(StampFactory.forKind(actionAndReason.getStackKind()), merge));

                        speculationPhi = graph.addWithoutUnique(new ValuePhiNode(StampFactory.forKind(speculation.getStackKind()), merge));

                        merge.addForwardEnd(firstEnd);

                        reasonActionPhi.addInput(actionAndReason);

                        speculationPhi.addInput(speculation);

                        target.replaceAtPredecessor(firstEnd);

                        exitLoops((AbstractDeoptimizeNode) target, firstEnd, cfg);

                        obsoletes = new LinkedList<>();

                        obsoletes.add((AbstractDeoptimizeNode) target);

                        target = merge;

                    } else {

                        merge = (AbstractMergeNode) target;

                    }

                    EndNode newEnd = graph.add(new EndNode());

                    merge.addForwardEnd(newEnd);

                    reasonActionPhi.addInput(deopt.getActionAndReason(context.getMetaAccess()));

                    speculationPhi.addInput(deopt.getSpeculation(context.getMetaAccess()));

                    deopt.replaceAtPredecessor(newEnd);

                    exitLoops(deopt, newEnd, cfg);

                    obsoletes.add(deopt);

                }

            }

            if (obsoletes != null) {

                ((DynamicDeoptimizeNode) ((AbstractMergeNode) target).next()).setStateBefore(fs);

                for (AbstractDeoptimizeNode obsolete : obsoletes) {

                    obsolete.safeDelete();

                }

            }

        }

    }

    private static void exitLoops(AbstractDeoptimizeNode deopt, EndNode end, ControlFlowGraph cfg) {

        Block block = cfg.blockFor(deopt);

        Loop<Block> loop = block.getLoop();

        while (loop != null) {

            end.graph().addBeforeFixed(end, end.graph().add(new LoopExitNode((LoopBeginNode) loop.getHeader().getBeginNode())));

            loop = loop.getParent();

        }

    }

    @Override

    public float codeSizeIncrease() {

        return 2.5f;

    }

}