1 /* 2 * Copyright (c) 2012, 2012, 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.Stamp; 26 import org.graalvm.compiler.debug.GraalError; 27 import org.graalvm.compiler.nodes.StructuredGraph; 28 import org.graalvm.compiler.nodes.ValueNode; 29 30 /** 31 * This class describes a value node that is an induction variable in a counted loop. 32 */ 33 public abstract class InductionVariable { 34 35 public enum Direction { 36 Up, 37 Down; 38 39 public Direction opposite() { 40 switch (this) { 41 case Up: 42 return Down; 43 case Down: 44 return Up; 45 default: 46 throw GraalError.shouldNotReachHere(); 47 } 48 } 49 } 50 51 public abstract StructuredGraph graph(); 52 53 protected final LoopEx loop; 54 55 public InductionVariable(LoopEx loop) { 56 this.loop = loop; 57 } 58 59 public LoopEx getLoop() { 60 return loop; 61 } 62 63 public abstract Direction direction(); 64 65 /** 66 * Returns the value node that is described by this induction variable. 67 */ 68 public abstract ValueNode valueNode(); 69 70 /** 71 * Returns the node that gives the initial value of this induction variable. 72 */ 73 public abstract ValueNode initNode(); 74 75 /** 76 * Returns the stride of the induction variable. The stride is the value that is added to the 77 * induction variable at each iteration. 78 */ 79 public abstract ValueNode strideNode(); 80 81 public abstract boolean isConstantInit(); 82 83 public abstract boolean isConstantStride(); 84 85 public abstract long constantInit(); 86 87 public abstract long constantStride(); 88 89 /** 90 * Returns the extremum value of the induction variable. The extremum value is the value of the 91 * induction variable in the loop body of the last iteration, only taking into account the main 92 * loop limit test. It's possible for the loop to exit before this value if 93 * {@link CountedLoopInfo#isExactTripCount()} returns false for the containing loop. 94 */ 95 public ValueNode extremumNode() { 96 return extremumNode(false, valueNode().stamp()); 97 } 98 99 public abstract ValueNode extremumNode(boolean assumePositiveTripCount, Stamp stamp); 100 101 public abstract boolean isConstantExtremum(); 102 103 public abstract long constantExtremum(); 104 105 /** 106 * Returns the exit value of the induction variable. The exit value is the value of the 107 * induction variable at the loop exit. 108 */ 109 public abstract ValueNode exitValueNode(); 110 111 /** 112 * Deletes any nodes created within the scope of this object that have no usages. 113 */ 114 public abstract void deleteUnusedNodes(); 115 }