/*

 * 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.

 *

 * 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 java.util.EnumMap;

import org.graalvm.word.LocationIdentity;

import jdk.vm.ci.meta.JavaKind;

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

/**

 * A {@link LocationIdentity} with a name.

 */

public class NamedLocationIdentity extends LocationIdentity implements FormatWithToString {

    /**

     * 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.

     */

    public static final LocationIdentity FINAL_LOCATION = NamedLocationIdentity.immutable("FINAL_LOCATION");

    /**

     * 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.

     */

    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.

     *

     * @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.

     *

     * @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.

     *

     * @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.

     */

    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;

    }

}