/*
 * Copyright (c) 2011, 2015, 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.nodes.calc;

import com.oracle.graal.api.meta.*;
import com.oracle.graal.compiler.common.type.*;
import com.oracle.graal.compiler.common.type.ArithmeticOpTable.ShiftOp.UShr;
import com.oracle.graal.graph.*;
import com.oracle.graal.graph.spi.*;
import com.oracle.graal.lir.gen.*;
import com.oracle.graal.nodeinfo.*;
import com.oracle.graal.nodes.*;
import com.oracle.graal.nodes.spi.*;

@NodeInfo(shortName = ">>>")
public final class UnsignedRightShiftNode extends ShiftNode<UShr> {

    public static final NodeClass<UnsignedRightShiftNode> TYPE = NodeClass.create(UnsignedRightShiftNode.class);

    public UnsignedRightShiftNode(ValueNode x, ValueNode y) {
        super(TYPE, ArithmeticOpTable::getUShr, x, y);
    }

    @Override
    public ValueNode canonical(CanonicalizerTool tool, ValueNode forX, ValueNode forY) {
        ValueNode ret = super.canonical(tool, forX, forY);
        if (ret != this) {
            return ret;
        }

        if (forY.isConstant()) {
            int amount = forY.asJavaConstant().asInt();
            int originalAmout = amount;
            int mask = getShiftAmountMask();
            amount &= mask;
            if (amount == 0) {
                return forX;
            }
            if (forX instanceof ShiftNode) {
                ShiftNode<?> other = (ShiftNode<?>) forX;
                if (other.getY().isConstant()) {
                    int otherAmount = other.getY().asJavaConstant().asInt() & mask;
                    if (other instanceof UnsignedRightShiftNode) {
                        int total = amount + otherAmount;
                        if (total != (total & mask)) {
                            return ConstantNode.forIntegerKind(getKind(), 0);
                        }
                        return new UnsignedRightShiftNode(other.getX(), ConstantNode.forInt(total));
                    } else if (other instanceof LeftShiftNode && otherAmount == amount) {
                        if (getKind() == Kind.Long) {
                            return new AndNode(other.getX(), ConstantNode.forLong(-1L >>> amount));
                        } else {
                            assert getKind() == Kind.Int;
                            return new AndNode(other.getX(), ConstantNode.forInt(-1 >>> amount));
                        }
                    }
                }
            }
            if (originalAmout != amount) {
                return new UnsignedRightShiftNode(forX, ConstantNode.forInt(amount));
            }
        }
        return this;
    }

    @Override
    public void generate(NodeMappableLIRBuilder builder, ArithmeticLIRGenerator gen) {
        builder.setResult(this, gen.emitUShr(builder.operand(getX()), builder.operand(getY())));
    }
}