/*

 * Copyright (c) 2009, 2016, 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.nodes.cfg;

import java.util.ArrayList;

import java.util.Iterator;

import org.graalvm.compiler.core.common.LocationIdentity;

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

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

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

import org.graalvm.compiler.graph.Node;

import org.graalvm.compiler.nodes.AbstractBeginNode;

import org.graalvm.compiler.nodes.FixedNode;

import org.graalvm.compiler.nodes.FixedWithNextNode;

import org.graalvm.compiler.nodes.InvokeWithExceptionNode;

import org.graalvm.compiler.nodes.LoopBeginNode;

import org.graalvm.compiler.nodes.LoopEndNode;

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

public final class Block extends AbstractBlockBase<Block> {

    public static final Block[] EMPTY_ARRAY = new Block[0];

    protected final AbstractBeginNode beginNode;

    protected FixedNode endNode;

    protected double probability;

    protected Loop<Block> loop;

    protected Block postdominator;

    protected Block distancedDominatorCache;

    private LocationSet killLocations;

    private LocationSet killLocationsBetweenThisAndDominator;

    protected Block(AbstractBeginNode node) {

        this.beginNode = node;

    }

    public AbstractBeginNode getBeginNode() {

        return beginNode;

    }

    public FixedNode getEndNode() {

        return endNode;

    }

    @Override

    public Loop<Block> getLoop() {

        return loop;

    }

    public void setLoop(Loop<Block> loop) {

        this.loop = loop;

    }

    @Override

    public int getLoopDepth() {

        return loop == null ? 0 : loop.getDepth();

    }

    @Override

    public boolean isLoopHeader() {

        return getBeginNode() instanceof LoopBeginNode;

    }

    @Override

    public boolean isLoopEnd() {

        return getEndNode() instanceof LoopEndNode;

    }

    @Override

    public boolean isExceptionEntry() {

        Node predecessor = getBeginNode().predecessor();

        return predecessor != null && predecessor instanceof InvokeWithExceptionNode && getBeginNode() == ((InvokeWithExceptionNode) predecessor).exceptionEdge();

    }

    public Block getFirstPredecessor() {

        return getPredecessors()[0];

    }

    public Block getFirstSuccessor() {

        return getSuccessors()[0];

    }

    public Block getEarliestPostDominated() {

        Block b = this;

        while (true) {

            Block dom = b.getDominator();

            if (dom != null && dom.getPostdominator() == b) {

                b = dom;

            } else {

                break;

            }

        }

        return b;

    }

    @Override

    public Block getPostdominator() {

        return postdominator;

    }

    private class NodeIterator implements Iterator<FixedNode> {

        private FixedNode cur;

        NodeIterator() {

            cur = getBeginNode();

        }

        @Override

        public boolean hasNext() {

            return cur != null;

        }

        @Override

        public FixedNode next() {

            FixedNode result = cur;

            if (result instanceof FixedWithNextNode) {

                FixedWithNextNode fixedWithNextNode = (FixedWithNextNode) result;

                FixedNode next = fixedWithNextNode.next();

                if (next instanceof AbstractBeginNode) {

                    next = null;

                }

                cur = next;

            } else {

                cur = null;

            }

            assert !(cur instanceof AbstractBeginNode);

            return result;

        }

        @Override

        public void remove() {

            throw new UnsupportedOperationException();

        }

    }

    public Iterable<FixedNode> getNodes() {

        return new Iterable<FixedNode>() {

            @Override

            public Iterator<FixedNode> iterator() {

                return new NodeIterator();

            }

            @Override

            public String toString() {

                StringBuilder str = new StringBuilder().append('[');

                for (FixedNode node : this) {

                    str.append(node).append(", ");

                }

                if (str.length() > 1) {

                    str.setLength(str.length() - 2);

                }

                return str.append(']').toString();

            }

        };

    }

    @Override

    public String toString() {

        return "B" + id;

    }

    @Override

    public double probability() {

        return probability;

    }

    public void setProbability(double probability) {

        assert probability >= 0 && Double.isFinite(probability);

        this.probability = probability;

    }

    @Override

    public Block getDominator(int distance) {

        Block result = this;

        for (int i = 0; i < distance; ++i) {

            result = result.getDominator();

        }

        return result;

    }

    public boolean canKill(LocationIdentity location) {

        if (location.isImmutable()) {

            return false;

        }

        return getKillLocations().contains(location);

    }

    public LocationSet getKillLocations() {

        if (killLocations == null) {

            killLocations = calcKillLocations();

        }

        return killLocations;

    }

    private LocationSet calcKillLocations() {

        LocationSet result = new LocationSet();

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

            if (node instanceof MemoryCheckpoint.Single) {

                LocationIdentity identity = ((MemoryCheckpoint.Single) node).getLocationIdentity();

                result.add(identity);

            } else if (node instanceof MemoryCheckpoint.Multi) {

                for (LocationIdentity identity : ((MemoryCheckpoint.Multi) node).getLocationIdentities()) {

                    result.add(identity);

                }

            }

            if (result.isAny()) {

                break;

            }

        }

        return result;

    }

    public boolean canKillBetweenThisAndDominator(LocationIdentity location) {

        if (location.isImmutable()) {

            return false;

        }

        return this.getKillLocationsBetweenThisAndDominator().contains(location);

    }

    private LocationSet getKillLocationsBetweenThisAndDominator() {

        if (this.killLocationsBetweenThisAndDominator == null) {

            LocationSet dominatorResult = new LocationSet();

            Block stopBlock = getDominator();

            if (this.isLoopHeader()) {

                assert stopBlock.getLoopDepth() < this.getLoopDepth();

                dominatorResult.addAll(((HIRLoop) this.getLoop()).getKillLocations());

            } else {

                for (Block b : this.getPredecessors()) {

                    assert !this.isLoopHeader();

                    if (b != stopBlock) {

                        dominatorResult.addAll(b.getKillLocations());

                        if (dominatorResult.isAny()) {

                            break;

                        }

                        b.calcKillLocationsBetweenThisAndTarget(dominatorResult, stopBlock);

                        if (dominatorResult.isAny()) {

                            break;

                        }

                    }

                }

            }

            this.killLocationsBetweenThisAndDominator = dominatorResult;

        }

        return this.killLocationsBetweenThisAndDominator;

    }

    private void calcKillLocationsBetweenThisAndTarget(LocationSet result, Block stopBlock) {

        assert AbstractControlFlowGraph.dominates(stopBlock, this);

        if (stopBlock == this || result.isAny()) {

            // We reached the stop block => nothing to do.

            return;

        } else {

            if (stopBlock == this.getDominator()) {

                result.addAll(this.getKillLocationsBetweenThisAndDominator());

            } else {

                // Divide and conquer: Aggregate kill locations from this to the dominator and then

                // from the dominator onwards.

                calcKillLocationsBetweenThisAndTarget(result, this.getDominator());

                result.addAll(this.getDominator().getKillLocations());

                if (result.isAny()) {

                    return;

                }

                this.getDominator().calcKillLocationsBetweenThisAndTarget(result, stopBlock);

            }

        }

    }

    @Override

    public void delete() {

        // adjust successor and predecessor lists

        Block next = getSuccessors()[0];

        for (Block pred : getPredecessors()) {

            Block[] predSuccs = pred.successors;

            Block[] newPredSuccs = new Block[predSuccs.length];

            for (int i = 0; i < predSuccs.length; ++i) {

                if (predSuccs[i] == this) {

                    newPredSuccs[i] = next;

                } else {

                    newPredSuccs[i] = predSuccs[i];

                }

            }

            pred.setSuccessors(newPredSuccs);

        }

        ArrayList<Block> newPreds = new ArrayList<>();

        for (int i = 0; i < next.getPredecessorCount(); i++) {

            Block curPred = next.getPredecessors()[i];

            if (curPred == this) {

                for (Block b : getPredecessors()) {

                    newPreds.add(b);

                }

            } else {

                newPreds.add(curPred);

            }

        }

        next.setPredecessors(newPreds.toArray(new Block[0]));

    }

}