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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * This code is free software; you can redistribute it and/or modify it
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 * 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.
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package com.oracle.graal.loop;

import com.oracle.graal.api.code.*;
import com.oracle.graal.api.meta.*;
import com.oracle.graal.graph.*;
import com.oracle.graal.graph.NodeClass.NodeClassIterator;
import com.oracle.graal.graph.NodeClass.Position;
import com.oracle.graal.nodes.*;
import com.oracle.graal.nodes.extended.*;
import com.oracle.graal.phases.*;
import com.oracle.graal.phases.common.*;

public abstract class LoopTransformations {

    private static final int UNROLL_LIMIT = GraalOptions.FullUnrollMaxNodes * 2;

    private LoopTransformations() {
        // does not need to be instantiated
    }

    public static void invert(LoopEx loop, FixedNode point) {
        LoopFragmentInsideBefore head = loop.insideBefore(point);
        LoopFragmentInsideBefore duplicate = head.duplicate();
        head.disconnect();
        head.insertBefore(loop);
        duplicate.appendInside(loop);
    }

    public static void peel(LoopEx loop) {
        loop.inside().duplicate().insertBefore(loop);
    }

    public static void fullUnroll(LoopEx loop, MetaAccessProvider runtime, Assumptions assumptions) {
        // assert loop.isCounted(); //TODO (gd) strenghten : counted with known trip count
        int iterations = 0;
        LoopBeginNode loopBegin = loop.loopBegin();
        StructuredGraph graph = (StructuredGraph) loopBegin.graph();
        while (!loopBegin.isDeleted()) {
            int mark = graph.getMark();
            peel(loop);
            new CanonicalizerPhase(null, runtime, assumptions, mark, null).apply(graph);
            if (iterations++ > UNROLL_LIMIT || graph.getNodeCount() > GraalOptions.MaximumDesiredSize * 3) {
                throw new BailoutException("FullUnroll : Graph seems to grow out of proportion");
            }
        }
    }

    public static void unswitch(LoopEx loop, ControlSplitNode controlSplitNode) {
        LoopFragmentWhole originalLoop = loop.whole();
        // create new control split out of loop
        ControlSplitNode newControlSplit = (ControlSplitNode) controlSplitNode.copyWithInputs();
        originalLoop.entryPoint().replaceAtPredecessor(newControlSplit);

        NodeClassIterator successors = controlSplitNode.successors().iterator();
        assert successors.hasNext();
        // original loop is used as first successor
        Position firstPosition = successors.nextPosition();
        NodeClass controlSplitClass = controlSplitNode.getNodeClass();
        controlSplitClass.set(newControlSplit, firstPosition, BeginNode.begin(originalLoop.entryPoint()));

        StructuredGraph graph = (StructuredGraph) controlSplitNode.graph();
        while (successors.hasNext()) {
            Position position = successors.nextPosition();
            // create a new loop duplicate, connect it and simplify it
            LoopFragmentWhole duplicateLoop = originalLoop.duplicate();
            controlSplitClass.set(newControlSplit, position, BeginNode.begin(duplicateLoop.entryPoint()));
            ControlSplitNode duplicatedControlSplit = duplicateLoop.getDuplicatedNode(controlSplitNode);
            graph.removeSplitPropagate(duplicatedControlSplit, (BeginNode) controlSplitClass.get(duplicatedControlSplit, position));
        }
        // original loop is simplified last to avoid deleting controlSplitNode too early
        graph.removeSplitPropagate(controlSplitNode, (BeginNode) controlSplitClass.get(controlSplitNode, firstPosition));
        // TODO (gd) probabilities need some amount of fixup.. (probably also in other transforms)
    }

    public static void unroll(LoopEx loop, int factor) {
        assert loop.isCounted();
        if (factor > 0) {
            throw new UnsupportedOperationException();
        }
        // TODO (gd) implement counted loop
        LoopFragmentWhole main = loop.whole();
        LoopFragmentWhole prologue = main.duplicate();
        prologue.insertBefore(loop);
        // CountedLoopBeginNode counted = prologue.countedLoop();
        // StructuredGraph graph = (StructuredGraph) counted.graph();
        // ValueNode tripCountPrologue = counted.tripCount();
        // ValueNode tripCountMain = counted.tripCount();
        // graph.replaceFloating(tripCountPrologue, "tripCountPrologue % factor");
        // graph.replaceFloating(tripCountMain, "tripCountMain - (tripCountPrologue % factor)");
        LoopFragmentInside inside = loop.inside();
        for (int i = 0; i < factor; i++) {
            inside.duplicate().appendInside(loop);
        }
    }

    public static ControlSplitNode findUnswitchable(LoopEx loop) {
        for (IfNode ifNode : loop.whole().nodes().filter(IfNode.class)) {
            if (loop.isOutsideLoop(ifNode.condition())) {
                return ifNode;
            }
        }
        for (SwitchNode switchNode : loop.whole().nodes().filter(SwitchNode.class)) {
            if (switchNode.successors().count() > 1 && loop.isOutsideLoop(switchNode.value())) {
                return switchNode;
            }
        }
        return null;
    }
}