/*

 * 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;

import static org.graalvm.compiler.nodeinfo.InputType.Association;

import static org.graalvm.compiler.nodeinfo.NodeCycles.CYCLES_0;

import static org.graalvm.compiler.nodeinfo.NodeSize.SIZE_0;

import org.graalvm.compiler.graph.IterableNodeType;

import org.graalvm.compiler.graph.Node;

import org.graalvm.compiler.graph.NodeClass;

import org.graalvm.compiler.graph.iterators.NodeIterable;

import org.graalvm.compiler.graph.spi.Simplifiable;

import org.graalvm.compiler.graph.spi.SimplifierTool;

import org.graalvm.compiler.nodeinfo.NodeInfo;

import org.graalvm.compiler.nodes.util.GraphUtil;

@NodeInfo(allowedUsageTypes = {Association}, cycles = CYCLES_0, size = SIZE_0)

public final class LoopExitNode extends BeginStateSplitNode implements IterableNodeType, Simplifiable {

    public static final NodeClass<LoopExitNode> TYPE = NodeClass.create(LoopExitNode.class);

    /*

     * The declared type of the field cannot be LoopBeginNode, because loop explosion during partial

     * evaluation can temporarily assign a non-loop begin. This node will then be deleted shortly

     * after - but we still must not have type system violations for that short amount of time.

     */

    @Input(Association) AbstractBeginNode loopBegin;

    public LoopExitNode(LoopBeginNode loop) {

        super(TYPE);

        assert loop != null;

        loopBegin = loop;

    }

    public LoopBeginNode loopBegin() {

        return (LoopBeginNode) loopBegin;

    }

    @Override

    public NodeIterable<Node> anchored() {

        return super.anchored().filter(n -> {

            if (n instanceof ProxyNode) {

                ProxyNode proxyNode = (ProxyNode) n;

                return proxyNode.proxyPoint() != this;

            }

            return true;

        });

    }

    @Override

    public void prepareDelete(FixedNode evacuateFrom) {

        removeProxies();

        super.prepareDelete(evacuateFrom);

    }

    public void removeProxies() {

        if (this.hasUsages()) {

            outer: while (true) {

                for (ProxyNode vpn : proxies().snapshot()) {

                    ValueNode value = vpn.value();

                    vpn.replaceAtUsagesAndDelete(value);

                    if (value == this) {

                        // Guard proxy could have this input as value.

                        continue outer;

                    }

                }

                break;

            }

        }

    }

    @SuppressWarnings({"unchecked", "rawtypes"})

    public NodeIterable<ProxyNode> proxies() {

        return (NodeIterable) usages().filter(n -> {

            if (n instanceof ProxyNode) {

                ProxyNode proxyNode = (ProxyNode) n;

                return proxyNode.proxyPoint() == this;

            }

            return false;

        });

    }

    public void removeExit() {

        this.removeProxies();

        FrameState loopStateAfter = this.stateAfter();

        graph().replaceFixedWithFixed(this, graph().add(new BeginNode()));

        if (loopStateAfter != null) {

            GraphUtil.tryKillUnused(loopStateAfter);

        }

    }

    @Override

    public void simplify(SimplifierTool tool) {

        Node prev = this.predecessor();

        while (tool.allUsagesAvailable() && prev instanceof BeginNode && prev.hasNoUsages()) {

            AbstractBeginNode begin = (AbstractBeginNode) prev;

            this.setNodeSourcePosition(begin.getNodeSourcePosition());

            prev = prev.predecessor();

            graph().removeFixed(begin);

        }

    }

}