1 /* 2 * Copyright (c) 2009, 2019, 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 such that {@code method.codeSize() == 0 || bci < method.getCodeSize()}. That 47 * is, if code size is 0 then allow any value, otherwise the bci must be less than 48 * the code size. 49 */ 50 public BytecodePosition(BytecodePosition caller, ResolvedJavaMethod method, int bci) { 51 assert method != null; 52 this.caller = caller; 53 this.method = method; 54 this.bci = bci; 55 int codeSize = method.getCodeSize(); 56 if (codeSize != 0 && bci >= codeSize) { 57 throw new IllegalArgumentException(String.format("bci %d is out of range for %s %d bytes", bci, method.format("%H.%n(%p)"), codeSize)); 58 } 59 } 60 61 /** 62 * Converts this code position to a string representation. 63 * 64 * @return a string representation of this code position 65 */ 66 @Override 67 public String toString() { 68 return CodeUtil.append(new StringBuilder(100), this).toString(); 69 } 70 71 /** 72 * Deep equality test. 73 */ 74 @Override 75 public boolean equals(Object obj) { 76 if (obj == this) { 77 return true; 78 } 79 if (obj != null && getClass() == obj.getClass()) { 80 BytecodePosition that = (BytecodePosition) obj; 81 if (this.bci == that.bci && Objects.equals(this.getMethod(), that.getMethod()) && Objects.equals(this.caller, that.caller)) { 82 return true; 83 } 84 } 85 return false; 86 } 87 88 @Override 89 public int hashCode() { 90 int hc = method.hashCode() * 31 + bci; 91 if (caller != null) { 92 hc = (hc * 31) + caller.hashCode(); 93 } 94 return hc; 95 } 96 97 /** 98 * @return The location within the method, as a bytecode index. The constant {@code -1} may be 99 * used to indicate the location is unknown, for example within code synthesized by the 100 * compiler. 101 */ 102 public int getBCI() { 103 return bci; 104 } 105 106 /** 107 * @return The runtime interface method for this position. 108 */ 109 public ResolvedJavaMethod getMethod() { 110 return method; 111 } 112 113 /** 114 * The position where this position has been called, {@code null} if none. 115 */ 116 public BytecodePosition getCaller() { 117 return caller; 118 } 119 120 /** 121 * Adds a caller to the current position returning the new position. 122 */ 123 public BytecodePosition addCaller(BytecodePosition link) { 124 if (getCaller() == null) { 125 return new BytecodePosition(link, getMethod(), getBCI()); 126 } else { 127 return new BytecodePosition(getCaller().addCaller(link), getMethod(), getBCI()); 128 } 129 } 130 }