1 /*
   2  * Copyright (c) 2015, 2016, 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.loop;
  24 
  25 import org.graalvm.compiler.core.common.type.IntegerStamp;
  26 import org.graalvm.compiler.nodes.FixedNode;
  27 import org.graalvm.compiler.nodes.StructuredGraph;
  28 import org.graalvm.compiler.nodes.ValueNode;
  29 import org.graalvm.compiler.nodes.calc.BinaryArithmeticNode;
  30 import org.graalvm.compiler.nodes.calc.SignedDivNode;
  31 
  32 /**
  33  * Utility methods to perform integer math with some obvious constant folding first.
  34  */
  35 public class MathUtil {
  36     private static boolean isConstantOne(ValueNode v1) {
  37         return v1.isConstant() && v1.stamp() instanceof IntegerStamp && v1.asJavaConstant().asLong() == 1;
  38     }
  39 
  40     private static boolean isConstantZero(ValueNode v1) {
  41         return v1.isConstant() && v1.stamp() instanceof IntegerStamp && v1.asJavaConstant().asLong() == 0;
  42     }
  43 
  44     public static ValueNode add(StructuredGraph graph, ValueNode v1, ValueNode v2) {
  45         if (isConstantZero(v1)) {
  46             return v2;
  47         }
  48         if (isConstantZero(v2)) {
  49             return v1;
  50         }
  51         return BinaryArithmeticNode.add(graph, v1, v2);
  52     }
  53 
  54     public static ValueNode mul(StructuredGraph graph, ValueNode v1, ValueNode v2) {
  55         if (isConstantOne(v1)) {
  56             return v2;
  57         }
  58         if (isConstantOne(v2)) {
  59             return v1;
  60         }
  61         return BinaryArithmeticNode.mul(graph, v1, v2);
  62     }
  63 
  64     public static ValueNode sub(StructuredGraph graph, ValueNode v1, ValueNode v2) {
  65         if (isConstantZero(v2)) {
  66             return v1;
  67         }
  68         return BinaryArithmeticNode.sub(graph, v1, v2);
  69     }
  70 
  71     public static ValueNode divBefore(StructuredGraph graph, FixedNode before, ValueNode dividend, ValueNode divisor) {
  72         if (isConstantOne(divisor)) {
  73             return dividend;
  74         }
  75         SignedDivNode div = graph.add(new SignedDivNode(dividend, divisor));
  76         graph.addBeforeFixed(before, div);
  77         return div;
  78     }
  79 }