/*
 * Copyright (c) 2013, 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 com.oracle.graal.truffle.nodes;

import java.lang.reflect.*;

import sun.misc.*;

import com.oracle.graal.api.meta.*;
import com.oracle.graal.graph.*;
import com.oracle.graal.graph.spi.*;
import com.oracle.graal.nodes.*;
import com.oracle.graal.nodes.java.*;
import com.oracle.graal.nodes.spi.*;
import com.oracle.graal.nodes.type.*;

/**
 * @see LoadIndexedNode
 */
public final class LoadIndexedFinalNode extends AccessIndexedNode implements Canonicalizable {

    /**
     * Creates a new {@link LoadIndexedFinalNode}.
     * 
     * @param array the instruction producing the array
     * @param index the instruction producing the index
     * @param elementKind the element type
     */
    public LoadIndexedFinalNode(ValueNode array, ValueNode index, Kind elementKind) {
        super(createStamp(array, elementKind), array, index, elementKind);
    }

    @Override
    public Node canonical(CanonicalizerTool tool) {
        if (array().isConstant() && !array().isNullConstant() && index().isConstant()) {
            Object array = array().asConstant().asObject();
            long index = index().asConstant().asLong();
            if (index >= 0 && index < Array.getLength(array)) {
                int arrayBaseOffset = Unsafe.getUnsafe().arrayBaseOffset(array.getClass());
                int arrayIndexScale = Unsafe.getUnsafe().arrayIndexScale(array.getClass());
                Constant constant = tool.runtime().readUnsafeConstant(elementKind(), array, arrayBaseOffset + index * arrayIndexScale, elementKind() == Kind.Object);
                return ConstantNode.forConstant(constant, tool.runtime(), graph());
            }
        }
        return this;
    }

    private static Stamp createStamp(ValueNode array, Kind kind) {
        ResolvedJavaType type = ObjectStamp.typeOrNull(array);
        if (kind == Kind.Object && type != null) {
            return StampFactory.declared(type.getComponentType());
        } else {
            return StampFactory.forKind(kind);
        }
    }

    @Override
    public boolean inferStamp() {
        return updateStamp(createStamp(array(), elementKind()));
    }

    @Override
    public void lower(LoweringTool tool) {
        LoadIndexedNode loadIndexedNode = graph().add(new LoadIndexedNode(array(), index(), elementKind()));
        graph().replaceFixedWithFixed(this, loadIndexedNode);
        loadIndexedNode.lower(tool);
    }
}