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      */
BytecodePosition(BytecodePosition caller, ResolvedJavaMethod method, int bci)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
toString()67     public String toString() {
68         return CodeUtil.append(new StringBuilder(100), this).toString();
69     }
70 
71     /**
72      * Deep equality test.
73      */
74     @Override
equals(Object obj)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
hashCode()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      */
getBCI()102     public int getBCI() {
103         return bci;
104     }
105 
106     /**
107      * @return The runtime interface method for this position.
108      */
getMethod()109     public ResolvedJavaMethod getMethod() {
110         return method;
111     }
112 
113     /**
114      * The position where this position has been called, {@code null} if none.
115      */
getCaller()116     public BytecodePosition getCaller() {
117         return caller;
118     }
119 
120     /**
121      * Adds a caller to the current position returning the new position.
122      */
addCaller(BytecodePosition link)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 }
131