/*

 * 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

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

 * questions.

 */

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.graph.NodeMap;

import org.graalvm.compiler.nodes.AbstractBeginNode;

import org.graalvm.compiler.nodes.AbstractMergeNode;

import org.graalvm.compiler.nodes.LoopBeginNode;

import org.graalvm.compiler.nodes.LoopExitNode;

import org.graalvm.compiler.nodes.MemoryProxyNode;

import org.graalvm.compiler.nodes.PhiNode;

import org.graalvm.compiler.nodes.ProxyNode;

import org.graalvm.compiler.nodes.StructuredGraph;

import org.graalvm.compiler.nodes.VirtualState;

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;

/**

 * Verifies that the schedule of the graph is correct. Checks that floating reads are not killed

 * between definition and usage. Also checks that there are no usages spanning loop exits without a

 * proper proxy node.

 */

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

    private final BlockMap<List<Node>> blockToNodesMap;

    private final NodeMap<Block> nodeMap;

    private final StructuredGraph graph;

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

        ReentrantBlockIterator.apply(new ScheduleVerification(blockToNodesMap, nodeMap, startBlock.getBeginNode().graph()), startBlock);

        return true;

    }

    private ScheduleVerification(BlockMap<List<Node>> blockToNodesMap, NodeMap<Block> nodeMap, StructuredGraph graph) {

        this.blockToNodesMap = blockToNodesMap;

        this.nodeMap = nodeMap;

        this.graph = graph;

    }

    @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);

                }

            }

        }

        if (beginNode instanceof LoopExitNode) {

            LoopExitNode loopExitNode = (LoopExitNode) beginNode;

            for (ProxyNode proxy : loopExitNode.proxies()) {

                if (proxy instanceof MemoryProxyNode) {

                    MemoryProxyNode memoryProxyNode = (MemoryProxyNode) proxy;

                    addFloatingReadUsages(currentState, memoryProxyNode);

                }

            }

        }

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

            if (n instanceof MemoryCheckpoint) {

                if (n instanceof MemoryCheckpoint.Single) {

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

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

                } else if (n instanceof MemoryCheckpoint.Multi) {

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

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

                        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));

                    }

                }

            }

            assert nodeMap.get(n) == block;

            if (graph.hasValueProxies() && block.getLoop() != null && !(n instanceof VirtualState)) {

                for (Node usage : n.usages()) {

                    Node usageNode = usage;

                    if (usageNode instanceof PhiNode) {

                        PhiNode phiNode = (PhiNode) usage;

                        usageNode = phiNode.merge();

                    }

                    if (usageNode instanceof LoopExitNode) {

                        LoopExitNode loopExitNode = (LoopExitNode) usageNode;

                        if (loopExitNode.loopBegin() == n || loopExitNode.stateAfter() == n) {

                            continue;

                        }

                    }

                    Block usageBlock = nodeMap.get(usageNode);

                    Loop<Block> usageLoop = null;

                    if (usageNode instanceof ProxyNode) {

                        ProxyNode proxyNode = (ProxyNode) usageNode;

                        usageLoop = nodeMap.get(proxyNode.proxyPoint().loopBegin()).getLoop();

                    } else {

                        if (usageBlock.getBeginNode() instanceof LoopExitNode) {

                            // For nodes in the loop exit node block, we don't know for sure

                            // whether they are "in the loop" or not. It depends on whether

                            // one of their transient usages is a loop proxy node.

                            // For now, let's just assume those nodes are OK, i.e., "in the loop".

                            LoopExitNode loopExitNode = (LoopExitNode) usageBlock.getBeginNode();

                            usageLoop = nodeMap.get(loopExitNode.loopBegin()).getLoop();

                        } else {

                            usageLoop = usageBlock.getLoop();

                        }

                    }

                    assert usageLoop != null : n + ", " + nodeMap.get(n) + " / " + usageNode + ", " + nodeMap.get(usageNode);

                    while (usageLoop != block.getLoop() && usageLoop != null) {

                        usageLoop = usageLoop.getParent();

                    }

                    assert usageLoop != null : n + ", " + usageNode + ", " + usageBlock + ", " + usageBlock.getLoop() + ", " + block + ", " + block.getLoop();

                }

            }

        }

        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;

    }

}