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 * Copyright (c) 2012, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
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 * 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.
 *
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package org.graalvm.compiler.nodes.spi;

import org.graalvm.compiler.nodes.ValueNode;
import org.graalvm.compiler.nodes.ValuePhiNode;
import org.graalvm.compiler.nodes.ValueProxyNode;
import org.graalvm.compiler.nodes.util.GraphUtil;

public interface ArrayLengthProvider {

    
The different modes that determine what the results of GraphUtil.arrayLength and ArrayLengthProvider.findLength can be used for. 
/**
     * The different modes that determine what the results of {@link GraphUtil#arrayLength} and
     * {@link ArrayLengthProvider#findLength} can be used for.
     */
    enum FindLengthMode {
        
Use the result of GraphUtil.arrayLength and ArrayLengthProvider.findLength to replace the explicit load of the array length with a node that does not involve a memory access of the array length. Values that are defined inside a loop and flow out the loop need to be proxied by ValueProxyNode. When this mode is used, new necessary proxy nodes are created base on the proxies that were found while traversing the path to the length node. In addition, new phi nodes can be created. The caller is responsible for adding these nodes to the graph, i.e., the return value can be a node that is not yet added to the graph. 
/**
         * Use the result of {@link GraphUtil#arrayLength} and
         * {@link ArrayLengthProvider#findLength} to replace the explicit load of the array length
         * with a node that does not involve a memory access of the array length.
         *
         * Values that are defined inside a loop and flow out the loop need to be proxied by
         * {@link ValueProxyNode}. When this mode is used, new necessary proxy nodes are created
         * base on the proxies that were found while traversing the path to the length node. In
         * addition, new {@link ValuePhiNode phi nodes} can be created. The caller is responsible
         * for adding these nodes to the graph, i.e., the return value can be a node that is not yet
         * added to the graph.
         */
        CANONICALIZE_READ,

        
Use the result of GraphUtil.arrayLength and ArrayLengthProvider.findLength only for decisions whether a certain optimization is possible. No new nodes are created during the search, i.e., the result is either a node that is already in the graph, or null. 
/**
         * Use the result of {@link GraphUtil#arrayLength} and
         * {@link ArrayLengthProvider#findLength} only for decisions whether a certain optimization
         * is possible. No new nodes are created during the search, i.e., the result is either a
         * node that is already in the graph, or null.
         */
        SEARCH_ONLY
    }

    
Returns the length of the array described by this node, or null if it is not available. Details of the different modes are documented in FindLengthMode. This method should not be called directly. Use GraphUtil.arrayLength instead. 
/**
     * Returns the length of the array described by this node, or null if it is not available.
     * Details of the different modes are documented in {@link FindLengthMode}.
     *
     * This method should not be called directly. Use {@link GraphUtil#arrayLength} instead.
     */
    ValueNode findLength(FindLengthMode mode);
}