1 /*
   2  * Copyright (c) 2013, 2015, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  */
  23 package org.graalvm.compiler.replacements.nodes.arithmetic;
  24 
  25 import static org.graalvm.compiler.nodeinfo.NodeCycles.CYCLES_2;
  26 import static org.graalvm.compiler.nodeinfo.NodeSize.SIZE_2;
  27 
  28 import org.graalvm.compiler.core.common.type.IntegerStamp;
  29 import org.graalvm.compiler.graph.NodeClass;
  30 import org.graalvm.compiler.graph.spi.CanonicalizerTool;
  31 import org.graalvm.compiler.nodeinfo.NodeInfo;
  32 import org.graalvm.compiler.nodes.AbstractBeginNode;
  33 import org.graalvm.compiler.nodes.ConstantNode;
  34 import org.graalvm.compiler.nodes.ValueNode;
  35 import org.graalvm.compiler.nodes.calc.SubNode;
  36 import org.graalvm.compiler.nodes.spi.LoweringTool;
  37 import org.graalvm.compiler.nodes.util.GraphUtil;
  38 
  39 import jdk.vm.ci.meta.JavaConstant;
  40 import jdk.vm.ci.meta.JavaKind;
  41 
  42 /**
  43  * Node representing an exact integer substraction that will throw an {@link ArithmeticException} in
  44  * case the addition would overflow the 32 bit range.
  45  */
  46 @NodeInfo(cycles = CYCLES_2, size = SIZE_2)
  47 public final class IntegerSubExactNode extends SubNode implements IntegerExactArithmeticNode {
  48     public static final NodeClass<IntegerSubExactNode> TYPE = NodeClass.create(IntegerSubExactNode.class);
  49 
  50     public IntegerSubExactNode(ValueNode x, ValueNode y) {
  51         super(TYPE, x, y);
  52         setStamp(x.stamp().unrestricted());
  53         assert x.stamp().isCompatible(y.stamp()) && x.stamp() instanceof IntegerStamp;
  54     }
  55 
  56     @Override
  57     public boolean inferStamp() {
  58         /*
  59          * Note: it is not allowed to use the foldStamp method of the regular sub node as we do not
  60          * know the result stamp of this node if we do not know whether we may deopt. If we know we
  61          * can never overflow we will replace this node with its non overflow checking counterpart
  62          * anyway.
  63          */
  64         return false;
  65     }
  66 
  67     @Override
  68     public ValueNode canonical(CanonicalizerTool tool, ValueNode forX, ValueNode forY) {
  69         if (GraphUtil.unproxify(forX) == GraphUtil.unproxify(forY)) {
  70             return ConstantNode.forIntegerStamp(stamp(), 0);
  71         }
  72         if (forX.isConstant() && forY.isConstant()) {
  73             return canonicalXYconstant(forX, forY);
  74         } else if (forY.isConstant()) {
  75             long c = forY.asJavaConstant().asLong();
  76             if (c == 0) {
  77                 return forX;
  78             }
  79         }
  80         if (!IntegerStamp.subtractionCanOverflow((IntegerStamp) x.stamp(), (IntegerStamp) y.stamp())) {
  81             return new SubNode(x, y).canonical(tool);
  82         }
  83         return this;
  84     }
  85 
  86     private ValueNode canonicalXYconstant(ValueNode forX, ValueNode forY) {
  87         JavaConstant xConst = forX.asJavaConstant();
  88         JavaConstant yConst = forY.asJavaConstant();
  89         assert xConst.getJavaKind() == yConst.getJavaKind();
  90         try {
  91             if (xConst.getJavaKind() == JavaKind.Int) {
  92                 return ConstantNode.forInt(Math.subtractExact(xConst.asInt(), yConst.asInt()));
  93             } else {
  94                 assert xConst.getJavaKind() == JavaKind.Long;
  95                 return ConstantNode.forLong(Math.subtractExact(xConst.asLong(), yConst.asLong()));
  96             }
  97         } catch (ArithmeticException ex) {
  98             // The operation will result in an overflow exception, so do not canonicalize.
  99         }
 100         return this;
 101     }
 102 
 103     @Override
 104     public IntegerExactArithmeticSplitNode createSplit(AbstractBeginNode next, AbstractBeginNode deopt) {
 105         return graph().add(new IntegerSubExactSplitNode(stamp(), getX(), getY(), next, deopt));
 106     }
 107 
 108     @Override
 109     public void lower(LoweringTool tool) {
 110         IntegerExactArithmeticSplitNode.lower(tool, this);
 111     }
 112 }