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 * 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

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 *

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package org.graalvm.compiler.phases.schedule;

import java.util.List;

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

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

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

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

import org.graalvm.compiler.debug.DebugContext;

import org.graalvm.compiler.graph.Node;

import org.graalvm.compiler.nodes.AbstractBeginNode;

import org.graalvm.compiler.nodes.AbstractMergeNode;

import org.graalvm.compiler.nodes.LoopBeginNode;

import org.graalvm.compiler.nodes.PhiNode;

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

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

import org.graalvm.compiler.nodes.memory.FloatingReadNode;

import org.graalvm.compiler.nodes.memory.MemoryCheckpoint;

import org.graalvm.compiler.nodes.memory.MemoryNode;

import org.graalvm.compiler.nodes.memory.MemoryPhiNode;

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

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

import jdk.internal.vm.compiler.word.LocationIdentity;

public final class MemoryScheduleVerification extends BlockIteratorClosure<EconomicSet<FloatingReadNode>> {

    private final BlockMap<List<Node>> blockToNodesMap;

    public static boolean check(Block startBlock, BlockMap<List<Node>> blockToNodesMap) {

        ReentrantBlockIterator.apply(new MemoryScheduleVerification(blockToNodesMap), startBlock);

        return true;

    }

    private MemoryScheduleVerification(BlockMap<List<Node>> blockToNodesMap) {

        this.blockToNodesMap = blockToNodesMap;

    }

    @Override

    protected EconomicSet<FloatingReadNode> getInitialState() {

        return EconomicSet.create(Equivalence.IDENTITY);

    }

    @Override

    protected EconomicSet<FloatingReadNode> processBlock(Block block, EconomicSet<FloatingReadNode> currentState) {

        AbstractBeginNode beginNode = block.getBeginNode();

        if (beginNode instanceof AbstractMergeNode) {

            AbstractMergeNode abstractMergeNode = (AbstractMergeNode) beginNode;

            for (PhiNode phi : abstractMergeNode.phis()) {

                if (phi instanceof MemoryPhiNode) {

                    MemoryPhiNode memoryPhiNode = (MemoryPhiNode) phi;

                    addFloatingReadUsages(currentState, memoryPhiNode);

                }

            }

        }

        for (Node n : blockToNodesMap.get(block)) {

            if (n instanceof MemoryCheckpoint) {

                if (n instanceof MemoryCheckpoint.Single) {

                    MemoryCheckpoint.Single single = (MemoryCheckpoint.Single) n;

                    processLocation(n, single.getLocationIdentity(), currentState);

                } else if (n instanceof MemoryCheckpoint.Multi) {

                    MemoryCheckpoint.Multi multi = (MemoryCheckpoint.Multi) n;

                    for (LocationIdentity location : multi.getLocationIdentities()) {

                        processLocation(n, location, currentState);

                    }

                }

                addFloatingReadUsages(currentState, n);

            } else if (n instanceof MemoryNode) {

                addFloatingReadUsages(currentState, n);

            } else if (n instanceof FloatingReadNode) {

                FloatingReadNode floatingReadNode = (FloatingReadNode) n;

                if (floatingReadNode.getLastLocationAccess() != null && floatingReadNode.getLocationIdentity().isMutable()) {

                    if (currentState.contains(floatingReadNode)) {

                        // Floating read was found in the state.

                        currentState.remove(floatingReadNode);

                    } else {

                        throw new RuntimeException("Floating read node " + n + " was not found in the state, i.e., it was killed by a memory check point before its place in the schedule. Block=" +

                                        block + ", block begin: " + block.getBeginNode() + " block loop: " + block.getLoop() + ", " + blockToNodesMap.get(block).get(0));

                    }

                }

            }

        }

        return currentState;

    }

    private static void addFloatingReadUsages(EconomicSet<FloatingReadNode> currentState, Node n) {

        for (FloatingReadNode read : n.usages().filter(FloatingReadNode.class)) {

            if (read.getLastLocationAccess() == n && read.getLocationIdentity().isMutable()) {

                currentState.add(read);

            }

        }

    }

    private void processLocation(Node n, LocationIdentity location, EconomicSet<FloatingReadNode> currentState) {

        assert n != null;

        if (location.isImmutable()) {

            return;

        }

        for (FloatingReadNode r : cloneState(currentState)) {

            if (r.getLocationIdentity().overlaps(location)) {

                // This read is killed by this location.

                r.getDebug().log(DebugContext.VERBOSE_LEVEL, "%s removing %s from state", n, r);

                currentState.remove(r);

            }

        }

    }

    @Override

    protected EconomicSet<FloatingReadNode> merge(Block merge, List<EconomicSet<FloatingReadNode>> states) {

        EconomicSet<FloatingReadNode> result = states.get(0);

        for (int i = 1; i < states.size(); ++i) {

            result.retainAll(states.get(i));

        }

        return result;

    }

    @Override

    protected EconomicSet<FloatingReadNode> cloneState(EconomicSet<FloatingReadNode> oldState) {

        EconomicSet<FloatingReadNode> result = EconomicSet.create(Equivalence.IDENTITY);

        if (oldState != null) {

            result.addAll(oldState);

        }

        return result;

    }

    @Override

    protected List<EconomicSet<FloatingReadNode>> processLoop(Loop<Block> loop, EconomicSet<FloatingReadNode> initialState) {

        HIRLoop l = (HIRLoop) loop;

        for (MemoryPhiNode memoryPhi : ((LoopBeginNode) l.getHeader().getBeginNode()).memoryPhis()) {

            for (FloatingReadNode r : cloneState(initialState)) {

                if (r.getLocationIdentity().overlaps(memoryPhi.getLocationIdentity())) {

                    initialState.remove(r);

                }

            }

        }

        return ReentrantBlockIterator.processLoop(this, loop, initialState).exitStates;

    }

}