1 /* 2 * Copyright (c) 2009, 2011, 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.bytecode; 24 25 /** 26 * An abstract class that provides the state and methods common to {@link Bytecodes#LOOKUPSWITCH} 27 * and {@link Bytecodes#TABLESWITCH} instructions. 28 */ 29 public abstract class BytecodeSwitch { 30 31 /** 32 * The {@link BytecodeStream} containing the bytecode array. 33 */ 34 protected final BytecodeStream stream; 35 /** 36 * Index of start of switch instruction. 37 */ 38 protected final int bci; 39 /** 40 * Index of the start of the additional data for the switch instruction, aligned to a multiple 41 * of four from the method start. 42 */ 43 protected final int alignedBci; 44 45 /** 46 * Constructor for a {@link BytecodeStream}. 47 * 48 * @param stream the {@code BytecodeStream} containing the switch instruction 49 * @param bci the index in the stream of the switch instruction 50 */ 51 public BytecodeSwitch(BytecodeStream stream, int bci) { 52 this.stream = stream; 53 this.bci = bci; 54 this.alignedBci = (bci + 4) & 0xfffffffc; 55 } 56 57 /** 58 * Gets the current bytecode index. 59 * 60 * @return the current bytecode index 61 */ 62 public int bci() { 63 return bci; 64 } 65 66 /** 67 * Gets the index of the instruction denoted by the {@code i}'th switch target. 68 * 69 * @param i index of the switch target 70 * @return the index of the instruction denoted by the {@code i}'th switch target 71 */ 72 public int targetAt(int i) { 73 return bci + offsetAt(i); 74 } 75 76 /** 77 * Gets the index of the instruction for the default switch target. 78 * 79 * @return the index of the instruction for the default switch target 80 */ 81 public int defaultTarget() { 82 return bci + defaultOffset(); 83 } 84 85 /** 86 * Gets the offset from the start of the switch instruction to the default switch target. 87 * 88 * @return the offset to the default switch target 89 */ 90 public int defaultOffset() { 91 return stream.readInt(alignedBci); 92 } 93 94 /** 95 * Gets the key at {@code i}'th switch target index. 96 * 97 * @param i the switch target index 98 * @return the key at {@code i}'th switch target index 99 */ 100 public abstract int keyAt(int i); 101 102 /** 103 * Gets the offset from the start of the switch instruction for the {@code i}'th switch target. 104 * 105 * @param i the switch target index 106 * @return the offset to the {@code i}'th switch target 107 */ 108 public abstract int offsetAt(int i); 109 110 /** 111 * Gets the number of switch targets. 112 * 113 * @return the number of switch targets 114 */ 115 public abstract int numberOfCases(); 116 117 /** 118 * Gets the total size in bytes of the switch instruction. 119 * 120 * @return the total size in bytes of the switch instruction 121 */ 122 public abstract int size(); 123 124 }