1 /* 2 * Copyright (c) 2012, 2018, 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 24 25 package org.graalvm.compiler.loop; 26 27 import org.graalvm.compiler.core.common.type.Stamp; 28 import org.graalvm.compiler.debug.GraalError; 29 import org.graalvm.compiler.nodes.NodeView; 30 import org.graalvm.compiler.nodes.StructuredGraph; 31 import org.graalvm.compiler.nodes.ValueNode; 32 33 /** 34 * This class describes a value node that is an induction variable in a counted loop. 35 */ 36 public abstract class InductionVariable { 37 38 public enum Direction { 39 Up, 40 Down; 41 42 public Direction opposite() { 43 switch (this) { 44 case Up: 45 return Down; 46 case Down: 47 return Up; 48 default: 49 throw GraalError.shouldNotReachHere(); 50 } 51 } 52 } 53 54 public abstract StructuredGraph graph(); 55 56 protected final LoopEx loop; 57 58 public InductionVariable(LoopEx loop) { 59 this.loop = loop; 60 } 61 62 public LoopEx getLoop() { 63 return loop; 64 } 65 66 public abstract Direction direction(); 67 68 /** 69 * Returns the value node that is described by this induction variable. 70 */ 71 public abstract ValueNode valueNode(); 72 73 /** 74 * Returns the node that gives the initial value of this induction variable. 75 */ 76 public abstract ValueNode initNode(); 77 78 /** 79 * Returns the stride of the induction variable. The stride is the value that is added to the 80 * induction variable at each iteration. 81 */ 82 public abstract ValueNode strideNode(); 83 84 public abstract boolean isConstantInit(); 85 86 public abstract boolean isConstantStride(); 87 88 public abstract long constantInit(); 89 90 public abstract long constantStride(); 91 92 /** 93 * Returns the extremum value of the induction variable. The extremum value is the value of the 94 * induction variable in the loop body of the last iteration, only taking into account the main 95 * loop limit test. It's possible for the loop to exit before this value if 96 * {@link CountedLoopInfo#isExactTripCount()} returns false for the containing loop. 97 */ 98 public ValueNode extremumNode() { 99 return extremumNode(false, valueNode().stamp(NodeView.DEFAULT)); 100 } 101 102 public abstract ValueNode extremumNode(boolean assumePositiveTripCount, Stamp stamp); 103 104 public abstract boolean isConstantExtremum(); 105 106 public abstract long constantExtremum(); 107 108 /** 109 * Returns the exit value of the induction variable. The exit value is the value of the 110 * induction variable at the loop exit. 111 */ 112 public abstract ValueNode exitValueNode(); 113 114 /** 115 * Deletes any nodes created within the scope of this object that have no usages. 116 */ 117 public abstract void deleteUnusedNodes(); 118 }