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 jdk.vm.ci.code; 24 25 import java.util.Objects; 26 27 import jdk.vm.ci.meta.ResolvedJavaMethod; 28 29 /** 30 * Represents a code position, that is, a chain of inlined methods with bytecode locations, that is 31 * communicated from the compiler to the runtime system. A code position can be used by the runtime 32 * system to reconstruct a source-level stack trace for exceptions and to create 33 * {@linkplain BytecodeFrame frames} for deoptimization. 34 */ 35 public class BytecodePosition { 36 37 private final BytecodePosition caller; 38 private final ResolvedJavaMethod method; 39 private final int bci; 40 41 /** 42 * Constructs a new object representing a given parent/caller, a given method, and a given BCI. 43 * 44 * @param caller the parent position 45 * @param method the method 46 * @param bci a BCI within the method 47 */ 48 public BytecodePosition(BytecodePosition caller, ResolvedJavaMethod method, int bci) { 49 assert method != null; 50 this.caller = caller; 51 this.method = method; 52 this.bci = bci; 53 } 54 55 /** 56 * Converts this code position to a string representation. 57 * 58 * @return a string representation of this code position 59 */ 60 @Override 61 public String toString() { 62 return CodeUtil.append(new StringBuilder(100), this).toString(); 63 } 64 65 /** 66 * Deep equality test. 67 */ 68 @Override 69 public boolean equals(Object obj) { 70 if (obj == this) { 71 return true; 72 } 73 if (obj != null && getClass() == obj.getClass()) { 74 BytecodePosition that = (BytecodePosition) obj; 75 if (this.bci == that.bci && Objects.equals(this.getMethod(), that.getMethod()) && Objects.equals(this.caller, that.caller)) { 76 return true; 77 } 78 } 79 return false; 80 } 81 82 @Override 83 public int hashCode() { 84 return getBCI(); 85 } 86 87 /** 88 * @return The location within the method, as a bytecode index. The constant {@code -1} may be 89 * used to indicate the location is unknown, for example within code synthesized by the 90 * compiler. 91 */ 92 public int getBCI() { 93 return bci; 94 } 95 96 /** 97 * @return The runtime interface method for this position. 98 */ 99 public ResolvedJavaMethod getMethod() { 100 return method; 101 } 102 103 /** 104 * The position where this position has been called, {@code null} if none. 105 */ 106 public BytecodePosition getCaller() { 107 return caller; 108 } 109 110 /** 111 * Adds a caller to the current position returning the new position. 112 */ 113 public BytecodePosition addCaller(BytecodePosition link) { 114 if (getCaller() == null) { 115 return new BytecodePosition(link, getMethod(), getBCI()); 116 } else { 117 return new BytecodePosition(getCaller().addCaller(link), getMethod(), getBCI()); 118 } 119 } 120 }