001/*
002 * Copyright (c) 2013, 2015, Oracle and/or its affiliates. All rights reserved.
003 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
004 *
005 * This code is free software; you can redistribute it and/or modify it
006 * under the terms of the GNU General Public License version 2 only, as
007 * published by the Free Software Foundation.
008 *
009 * This code is distributed in the hope that it will be useful, but WITHOUT
010 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
011 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
012 * version 2 for more details (a copy is included in the LICENSE file that
013 * accompanied this code).
014 *
015 * You should have received a copy of the GNU General Public License version
016 * 2 along with this work; if not, write to the Free Software Foundation,
017 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
018 *
019 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
020 * or visit www.oracle.com if you need additional information or have any
021 * questions.
022 */
023package com.oracle.graal.replacements.nodes.arithmetic;
024
025import jdk.internal.jvmci.code.*;
026import jdk.internal.jvmci.meta.*;
027
028import com.oracle.graal.compiler.common.type.*;
029import com.oracle.graal.graph.*;
030import com.oracle.graal.graph.spi.*;
031import com.oracle.graal.nodeinfo.*;
032import com.oracle.graal.nodes.*;
033import com.oracle.graal.nodes.calc.*;
034import com.oracle.graal.nodes.spi.*;
035
036import static com.oracle.graal.compiler.common.type.IntegerStamp.*;
037
038/**
039 * Node representing an exact integer addition that will throw an {@link ArithmeticException} in
040 * case the addition would overflow the 32 bit range.
041 */
042@NodeInfo
043public final class IntegerAddExactNode extends AddNode implements IntegerExactArithmeticNode {
044    public static final NodeClass<IntegerAddExactNode> TYPE = NodeClass.create(IntegerAddExactNode.class);
045
046    public IntegerAddExactNode(ValueNode x, ValueNode y) {
047        super(TYPE, x, y);
048        setStamp(foldStamp(x.stamp(), y.stamp()));
049        assert x.stamp().isCompatible(y.stamp()) && x.stamp() instanceof IntegerStamp;
050    }
051
052    @Override
053    public boolean inferStamp() {
054        return updateStamp(foldStamp(x.stamp(), y.stamp()));
055    }
056
057    private static Stamp foldStamp(Stamp stamp1, Stamp stamp2) {
058        IntegerStamp a = (IntegerStamp) stamp1;
059        IntegerStamp b = (IntegerStamp) stamp2;
060
061        int bits = a.getBits();
062        assert bits == b.getBits();
063
064        long defaultMask = CodeUtil.mask(bits);
065        long variableBits = (a.downMask() ^ a.upMask()) | (b.downMask() ^ b.upMask());
066        long variableBitsWithCarry = variableBits | (carryBits(a.downMask(), b.downMask()) ^ carryBits(a.upMask(), b.upMask()));
067        long newDownMask = (a.downMask() + b.downMask()) & ~variableBitsWithCarry;
068        long newUpMask = (a.downMask() + b.downMask()) | variableBitsWithCarry;
069
070        newDownMask &= defaultMask;
071        newUpMask &= defaultMask;
072
073        long newLowerBound;
074        long newUpperBound;
075        boolean lowerOverflowsPositively = addOverflowsPositively(a.lowerBound(), b.lowerBound(), bits);
076        boolean upperOverflowsPositively = addOverflowsPositively(a.upperBound(), b.upperBound(), bits);
077        boolean lowerOverflowsNegatively = addOverflowsNegatively(a.lowerBound(), b.lowerBound(), bits);
078        boolean upperOverflowsNegatively = addOverflowsNegatively(a.upperBound(), b.upperBound(), bits);
079        if (lowerOverflowsPositively) {
080            newLowerBound = CodeUtil.maxValue(bits);
081        } else if (lowerOverflowsNegatively) {
082            newLowerBound = CodeUtil.minValue(bits);
083        } else {
084            newLowerBound = CodeUtil.signExtend((a.lowerBound() + b.lowerBound()) & defaultMask, bits);
085        }
086
087        if (upperOverflowsPositively) {
088            newUpperBound = CodeUtil.maxValue(bits);
089        } else if (upperOverflowsNegatively) {
090            newUpperBound = CodeUtil.minValue(bits);
091        } else {
092            newUpperBound = CodeUtil.signExtend((a.upperBound() + b.upperBound()) & defaultMask, bits);
093        }
094
095        IntegerStamp limit = StampFactory.forInteger(bits, newLowerBound, newUpperBound);
096        newUpMask &= limit.upMask();
097        newUpperBound = CodeUtil.signExtend(newUpperBound & newUpMask, bits);
098        newDownMask |= limit.downMask();
099        newLowerBound |= newDownMask;
100        return new IntegerStamp(bits, newLowerBound, newUpperBound, newDownMask, newUpMask);
101    }
102
103    @Override
104    public ValueNode canonical(CanonicalizerTool tool, ValueNode forX, ValueNode forY) {
105        ValueNode result = findSynonym(forX, forY);
106        if (result == null) {
107            return this;
108        } else {
109            return result;
110        }
111    }
112
113    private static ValueNode findSynonym(ValueNode forX, ValueNode forY) {
114        if (forX.isConstant() && !forY.isConstant()) {
115            return new IntegerAddExactNode(forY, forX);
116        }
117        if (forX.isConstant()) {
118            ConstantNode constantNode = canonicalXconstant(forX, forY);
119            if (constantNode != null) {
120                return constantNode;
121            }
122        } else if (forY.isConstant()) {
123            long c = forY.asJavaConstant().asLong();
124            if (c == 0) {
125                return forX;
126            }
127        }
128        return null;
129    }
130
131    private static ConstantNode canonicalXconstant(ValueNode forX, ValueNode forY) {
132        JavaConstant xConst = forX.asJavaConstant();
133        JavaConstant yConst = forY.asJavaConstant();
134        if (xConst != null && yConst != null) {
135            assert xConst.getKind() == yConst.getKind();
136            try {
137                if (xConst.getKind() == Kind.Int) {
138                    return ConstantNode.forInt(Math.addExact(xConst.asInt(), yConst.asInt()));
139                } else {
140                    assert xConst.getKind() == Kind.Long;
141                    return ConstantNode.forLong(Math.addExact(xConst.asLong(), yConst.asLong()));
142                }
143            } catch (ArithmeticException ex) {
144                // The operation will result in an overflow exception, so do not canonicalize.
145            }
146        }
147        return null;
148    }
149
150    @Override
151    public IntegerExactArithmeticSplitNode createSplit(AbstractBeginNode next, AbstractBeginNode deopt) {
152        return graph().add(new IntegerAddExactSplitNode(stamp(), getX(), getY(), next, deopt));
153    }
154
155    @Override
156    public void lower(LoweringTool tool) {
157        IntegerExactArithmeticSplitNode.lower(tool, this);
158    }
159}