/*

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

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 *

 * 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 org.graalvm.compiler.loop.phases;

import org.graalvm.compiler.loop.LoopEx;

import org.graalvm.compiler.loop.LoopsData;

import org.graalvm.compiler.nodes.FixedNode;

import org.graalvm.compiler.nodes.Invoke;

import org.graalvm.compiler.nodes.LoopEndNode;

import org.graalvm.compiler.nodes.StructuredGraph;

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

import org.graalvm.compiler.nodes.extended.ForeignCallNode;

import org.graalvm.compiler.phases.BasePhase;

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

public class LoopSafepointEliminationPhase extends BasePhase<MidTierContext> {

    @Override

    protected void run(StructuredGraph graph, MidTierContext context) {

        LoopsData loops = new LoopsData(graph);

        if (context.getOptimisticOptimizations().useLoopLimitChecks() && graph.getGuardsStage().allowsFloatingGuards()) {

            loops.detectedCountedLoops();

            for (LoopEx loop : loops.countedLoops()) {

                if (loop.loop().getChildren().isEmpty() && loop.counted().getStamp().getBits() <= 32) {

                    boolean hasSafepoint = false;

                    for (LoopEndNode loopEnd : loop.loopBegin().loopEnds()) {

                        hasSafepoint |= loopEnd.canSafepoint();

                    }

                    if (hasSafepoint) {

                        loop.counted().createOverFlowGuard();

                        loop.loopBegin().disableSafepoint();

                    }

                }

            }

        }

        for (LoopEx loop : loops.loops()) {

            for (LoopEndNode loopEnd : loop.loopBegin().loopEnds()) {

                Block b = loops.getCFG().blockFor(loopEnd);

                blocks: while (b != loop.loop().getHeader()) {

                    assert b != null;

                    for (FixedNode node : b.getNodes()) {

                        if (node instanceof Invoke || (node instanceof ForeignCallNode && ((ForeignCallNode) node).isGuaranteedSafepoint())) {

                            loopEnd.disableSafepoint();

                            break blocks;

                        }

                    }

                    b = b.getDominator();

                }

            }

        }

        loops.deleteUnusedNodes();

    }

}