hotspot/src/jdk.internal.vm.compiler/share/classes/org.graalvm.compiler.replacements/src/org/graalvm/compiler/replacements/nodes/ExplodeLoopNode.java

/*
 * Copyright (c) 2012, 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
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package org.graalvm.compiler.replacements.nodes;

import static org.graalvm.compiler.nodeinfo.NodeCycles.CYCLES_0;
import static org.graalvm.compiler.nodeinfo.NodeSize.SIZE_0;

import java.util.ArrayList;

import org.graalvm.compiler.api.replacements.Snippet.VarargsParameter;
import org.graalvm.compiler.core.common.type.StampFactory;
import org.graalvm.compiler.graph.Node;
import org.graalvm.compiler.graph.NodeClass;
import org.graalvm.compiler.nodeinfo.NodeInfo;
import org.graalvm.compiler.nodes.FixedWithNextNode;
import org.graalvm.compiler.nodes.LoopBeginNode;

/**
 * Placeholder node to denote to snippet preparation that the following loop must be completely
 * unrolled.
 *
 * @see VarargsParameter
 */
@NodeInfo(cycles = CYCLES_0, size = SIZE_0)
public final class ExplodeLoopNode extends FixedWithNextNode {
    public static final NodeClass<ExplodeLoopNode> TYPE = NodeClass.create(ExplodeLoopNode.class);

    public ExplodeLoopNode() {
        super(TYPE, StampFactory.forVoid());
    }

    public LoopBeginNode findLoopBegin() {
        Node currentNext = next();
        ArrayList<Node> succs = new ArrayList<>();
        while (!(currentNext instanceof LoopBeginNode)) {
            assert currentNext != null : "cannot find loop after " + this;
            for (Node n : currentNext.cfgSuccessors()) {
                succs.add(n);
            }
            if (succs.size() == 1) {
                currentNext = succs.get(0);
            } else {
                return null;
            }
        }
        return (LoopBeginNode) currentNext;
    }

    /**
     * A call to this method must be placed immediately prior to the loop that is to be exploded.
     */
    @NodeIntrinsic
    public static native void explodeLoop();
}