/*

 * 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.virtual.phases.ea;

import java.util.Iterator;

import org.graalvm.compiler.nodes.ValueNode;

import org.graalvm.word.LocationIdentity;

/**

 * This class maintains a set of known values, identified by base object, locations and offset.

 */

public final class ReadEliminationBlockState extends EffectsBlockState<ReadEliminationBlockState> {

    final EconomicMap<CacheEntry<?>, ValueNode> readCache;

    abstract static class CacheEntry<T> {

        public final ValueNode object;

        public final T identity;

        CacheEntry(ValueNode object, T identity) {

            this.object = object;

            this.identity = identity;

        }

        public abstract CacheEntry<T> duplicateWithObject(ValueNode newObject);

        @Override

        public int hashCode() {

            int result = 31 + ((identity == null) ? 0 : identity.hashCode());

            return 31 * result + ((object == null) ? 0 : object.hashCode());

        }

        @Override

        public boolean equals(Object obj) {

            if (!(obj instanceof CacheEntry<?>)) {

                return false;

            }

            CacheEntry<?> other = (CacheEntry<?>) obj;

            return identity.equals(other.identity) && object == other.object;

        }

        @Override

        public String toString() {

            return object + ":" + identity;

        }

        public abstract boolean conflicts(LocationIdentity other);

        public abstract LocationIdentity getIdentity();

    }

    static final class LoadCacheEntry extends CacheEntry<LocationIdentity> {

        LoadCacheEntry(ValueNode object, LocationIdentity identity) {

            super(object, identity);

        }

        @Override

        public CacheEntry<LocationIdentity> duplicateWithObject(ValueNode newObject) {

            return new LoadCacheEntry(newObject, identity);

        }

        @Override

        public boolean conflicts(LocationIdentity other) {

            return identity.equals(other);

        }

        @Override

        public LocationIdentity getIdentity() {

            return identity;

        }

    }

    /**

     * CacheEntry describing an Unsafe memory reference. The memory location and the location

     * identity are separate so both must be considered when looking for optimizable memory

     * accesses.

     */

    static final class UnsafeLoadCacheEntry extends CacheEntry<ValueNode> {

        private final LocationIdentity locationIdentity;

        UnsafeLoadCacheEntry(ValueNode object, ValueNode location, LocationIdentity locationIdentity) {

            super(object, location);

            assert locationIdentity != null;

            this.locationIdentity = locationIdentity;

        }

        @Override

        public CacheEntry<ValueNode> duplicateWithObject(ValueNode newObject) {

            return new UnsafeLoadCacheEntry(newObject, identity, locationIdentity);

        }

        @Override

        public boolean conflicts(LocationIdentity other) {

            return locationIdentity.equals(other);

        }

        @Override

        public int hashCode() {

            return 31 * super.hashCode() + locationIdentity.hashCode();

        }

        @Override

        public boolean equals(Object obj) {

            if (obj instanceof UnsafeLoadCacheEntry) {

                UnsafeLoadCacheEntry other = (UnsafeLoadCacheEntry) obj;

                return super.equals(other) && locationIdentity.equals(other.locationIdentity);

            }

            return false;

        }

        @Override

        public LocationIdentity getIdentity() {

            return locationIdentity;

        }

        @Override

        public String toString() {

            return "UNSAFE:" + super.toString() + " location:" + locationIdentity;

        }

    }

    public ReadEliminationBlockState() {

        readCache = EconomicMap.create(Equivalence.DEFAULT);

    }

    public ReadEliminationBlockState(ReadEliminationBlockState other) {

        readCache = EconomicMap.create(Equivalence.DEFAULT, other.readCache);

    }

    @Override

    public String toString() {

        return super.toString() + " " + readCache;

    }

    @Override

    public boolean equivalentTo(ReadEliminationBlockState other) {

        return isSubMapOf(readCache, other.readCache);

    }

    public void addCacheEntry(CacheEntry<?> identifier, ValueNode value) {

        readCache.put(identifier, value);

    }

    public ValueNode getCacheEntry(CacheEntry<?> identifier) {

        return readCache.get(identifier);

    }

    public void killReadCache() {

        readCache.clear();

    }

    public void killReadCache(LocationIdentity identity) {

        Iterator<CacheEntry<?>> iterator = readCache.getKeys().iterator();

        while (iterator.hasNext()) {

            CacheEntry<?> entry = iterator.next();

            if (entry.conflicts(identity)) {

                iterator.remove();

            }

        }

    }

    public EconomicMap<CacheEntry<?>, ValueNode> getReadCache() {

        return readCache;

    }

}