/*

 * 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 org.graalvm.compiler.nodes.calc;

import org.graalvm.compiler.core.common.type.ArithmeticOpTable;

import org.graalvm.compiler.core.common.type.ArithmeticOpTable.BinaryOp;

import org.graalvm.compiler.core.common.type.ArithmeticOpTable.BinaryOp.Sub;

import org.graalvm.compiler.core.common.type.IntegerStamp;

import org.graalvm.compiler.core.common.type.Stamp;

import org.graalvm.compiler.core.common.type.StampFactory;

import org.graalvm.compiler.graph.NodeClass;

import org.graalvm.compiler.graph.spi.CanonicalizerTool;

import org.graalvm.compiler.lir.gen.ArithmeticLIRGeneratorTool;

import org.graalvm.compiler.nodeinfo.NodeInfo;

import org.graalvm.compiler.nodes.ConstantNode;

import org.graalvm.compiler.nodes.ValueNode;

import org.graalvm.compiler.nodes.spi.NodeLIRBuilderTool;

import org.graalvm.compiler.nodes.util.GraphUtil;

import jdk.vm.ci.meta.Constant;

import jdk.vm.ci.meta.PrimitiveConstant;

@NodeInfo(shortName = "-")

public class SubNode extends BinaryArithmeticNode<Sub> implements NarrowableArithmeticNode {

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

    public SubNode(ValueNode x, ValueNode y) {

        this(TYPE, x, y);

    }

    protected SubNode(NodeClass<? extends SubNode> c, ValueNode x, ValueNode y) {

        super(c, ArithmeticOpTable::getSub, x, y);

    }

    public static ValueNode create(ValueNode x, ValueNode y) {

        BinaryOp<Sub> op = ArithmeticOpTable.forStamp(x.stamp()).getSub();

        Stamp stamp = op.foldStamp(x.stamp(), y.stamp());

        ConstantNode tryConstantFold = tryConstantFold(op, x, y, stamp);

        if (tryConstantFold != null) {

            return tryConstantFold;

        }

        return canonical(null, op, stamp, x, y);

    }

    private static ValueNode canonical(SubNode subNode, BinaryOp<Sub> op, Stamp stamp, ValueNode forX, ValueNode forY) {

        SubNode self = subNode;

        if (GraphUtil.unproxify(forX) == GraphUtil.unproxify(forY)) {

            Constant zero = op.getZero(forX.stamp());

            if (zero != null) {

                return ConstantNode.forPrimitive(stamp, zero);

            }

        }

        boolean associative = op.isAssociative();

        if (associative) {

            if (forX instanceof AddNode) {

                AddNode x = (AddNode) forX;

                if (x.getY() == forY) {

                    // (a + b) - b

                    return x.getX();

                }

                if (x.getX() == forY) {

                    // (a + b) - a

                    return x.getY();

                }

            } else if (forX instanceof SubNode) {

                SubNode x = (SubNode) forX;

                if (x.getX() == forY) {

                    // (a - b) - a

                    return NegateNode.create(x.getY());

                }

            }

            if (forY instanceof AddNode) {

                AddNode y = (AddNode) forY;

                if (y.getX() == forX) {

                    // a - (a + b)

                    return NegateNode.create(y.getY());

                }

                if (y.getY() == forX) {

                    // b - (a + b)

                    return NegateNode.create(y.getX());

                }

            } else if (forY instanceof SubNode) {

                SubNode y = (SubNode) forY;

                if (y.getX() == forX) {

                    // a - (a - b)

                    return y.getY();

                }

            }

        }

        if (forY.isConstant()) {

            Constant c = forY.asConstant();

            if (op.isNeutral(c)) {

                return forX;

            }

            if (associative && self != null) {

                ValueNode reassociated = reassociate(self, ValueNode.isConstantPredicate(), forX, forY);

                if (reassociated != self) {

                    return reassociated;

                }

            }

            if (c instanceof PrimitiveConstant && ((PrimitiveConstant) c).getJavaKind().isNumericInteger()) {

                long i = ((PrimitiveConstant) c).asLong();

                if (i < 0 || ((IntegerStamp) StampFactory.forKind(forY.getStackKind())).contains(-i)) {

                    // Adding a negative is more friendly to the backend since adds are

                    // commutative, so prefer add when it fits.

                    return BinaryArithmeticNode.add(forX, ConstantNode.forIntegerStamp(stamp, -i));

                }

            }

        } else if (forX.isConstant()) {

            Constant c = forX.asConstant();

            if (ArithmeticOpTable.forStamp(stamp).getAdd().isNeutral(c)) {

                /*

                 * Note that for floating point numbers, + and - have different neutral elements. We

                 * have to test for the neutral element of +, because we are doing this

                 * transformation: 0 - x == (-x) + 0 == -x.

                 */

                return NegateNode.create(forY);

            }

            if (associative && self != null) {

                return reassociate(self, ValueNode.isConstantPredicate(), forX, forY);

            }

        }

        if (forY instanceof NegateNode) {

            return BinaryArithmeticNode.add(forX, ((NegateNode) forY).getValue());

        }

        if (self == null) {

            self = new SubNode(forX, forY);

        }

        return self;

    }

    @Override

    public ValueNode canonical(CanonicalizerTool tool, ValueNode forX, ValueNode forY) {

        ValueNode ret = super.canonical(tool, forX, forY);

        if (ret != this) {

            return ret;

        }

        BinaryOp<Sub> op = getOp(forX, forY);

        return canonical(this, op, stamp, forX, forY);

    }

    @Override

    public void generate(NodeLIRBuilderTool nodeValueMap, ArithmeticLIRGeneratorTool gen) {

        nodeValueMap.setResult(this, gen.emitSub(nodeValueMap.operand(getX()), nodeValueMap.operand(getY()), false));

    }

}