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 * Copyright (c) 2011, 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.
 *
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package org.graalvm.compiler.nodes;

import java.util.EnumMap;

import jdk.internal.vm.compiler.collections.EconomicSet;
import jdk.internal.vm.compiler.collections.Equivalence;
import jdk.internal.vm.compiler.word.LocationIdentity;

import jdk.vm.ci.meta.JavaKind;
import jdk.vm.ci.meta.JavaKind.FormatWithToString;

A LocationIdentity with a name. /**
 * A {@link LocationIdentity} with a name.
 */
public class NamedLocationIdentity extends LocationIdentity implements FormatWithToString {

    
Map for asserting all NamedLocationIdentity instances have a unique name. /**
     * Map for asserting all {@link NamedLocationIdentity} instances have a unique name.
     */
    static class DB {
        private static final EconomicSet<String> map = EconomicSet.create(Equivalence.DEFAULT);

        static boolean checkUnique(String name) {
            if (!map.add(name)) {
                throw new AssertionError("identity " + name + " already exists");
            }
            return true;
        }
    }

    
Denotes the location of a value that is guaranteed to be unchanging.
/**
     * Denotes the location of a value that is guaranteed to be unchanging.
     */
    public static final LocationIdentity FINAL_LOCATION = NamedLocationIdentity.immutable("FINAL_LOCATION");

    
Denotes the location of the length field of a Java array.
/**
     * Denotes the location of the length field of a Java array.
     */
    public static final LocationIdentity ARRAY_LENGTH_LOCATION = NamedLocationIdentity.immutable("[].length");

    
Denotes an off-heap address.
/**
     * Denotes an off-heap address.
     */
    public static final LocationIdentity OFF_HEAP_LOCATION = NamedLocationIdentity.mutable("OFF_HEAP_LOCATION");

    private final String name;
    private final boolean immutable;

    protected NamedLocationIdentity(String name, boolean immutable) {
        this.name = name;
        this.immutable = immutable;
        assert DB.checkUnique(name);
    }

    
Creates a named unique location identity for read and write operations against mutable
memory.
Params:
name – the name of the new location identity/**
     * Creates a named unique location identity for read and write operations against mutable
     * memory.
     *
     * @param name the name of the new location identity
     */
    public static NamedLocationIdentity mutable(String name) {
        return create(name, false);
    }

    
Creates a named unique location identity for read operations against immutable memory.
Immutable memory will never have a visible write in the graph, which is more restrictive than
Java final.
Params:
name – the name of the new location identity/**
     * Creates a named unique location identity for read operations against immutable memory.
     * Immutable memory will never have a visible write in the graph, which is more restrictive than
     * Java final.
     *
     * @param name the name of the new location identity
     */
    public static NamedLocationIdentity immutable(String name) {
        return create(name, true);
    }

    
Creates a named unique location identity for read and write operations.
Params:
name – the name of the new location identity
immutable – true if the location is immutable/**
     * Creates a named unique location identity for read and write operations.
     *
     * @param name the name of the new location identity
     * @param immutable true if the location is immutable
     */
    private static NamedLocationIdentity create(String name, boolean immutable) {
        return new NamedLocationIdentity(name, immutable);
    }

    @Override
    public boolean isImmutable() {
        return immutable;
    }

    @Override
    public String toString() {
        return name + (isImmutable() ? ":final" : "");
    }

    
Returns the named location identity for an array of the given element kind. Array accesses of
the same kind must have the same location identity unless an alias analysis guarantees that
two distinct arrays are accessed.
/**
     * Returns the named location identity for an array of the given element kind. Array accesses of
     * the same kind must have the same location identity unless an alias analysis guarantees that
     * two distinct arrays are accessed.
     */
    public static LocationIdentity getArrayLocation(JavaKind elementKind) {
        return ARRAY_LOCATIONS.get(elementKind);
    }

    private static final EnumMap<JavaKind, LocationIdentity> ARRAY_LOCATIONS = initArrayLocations();

    private static EnumMap<JavaKind, LocationIdentity> initArrayLocations() {
        EnumMap<JavaKind, LocationIdentity> result = new EnumMap<>(JavaKind.class);
        for (JavaKind kind : JavaKind.values()) {
            result.put(kind, NamedLocationIdentity.mutable("Array: " + kind.getJavaName()));
        }
        return result;
    }
}