1 /*
2 * Copyright (c) 2001, 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 */
24
25 package sun.jvm.hotspot.interpreter;
26
27 import sun.jvm.hotspot.oops.*;
28 import sun.jvm.hotspot.runtime.*;
29 import sun.jvm.hotspot.utilities.*;
30
31 public class BytecodeStream {
32 private Method _method;
33
34 // reading position
35 private int _bci; // bci if current bytecode
36 private int _next_bci; // bci of next bytecode
37 private int _end_bci; // bci after the current iteration interval
38
39 // last bytecode read
40 private int _code;
41 private boolean _is_wide;
42
43 // Construction
44 public BytecodeStream(Method method) {
45 _method = method;
46 setInterval(0, (int) method.getCodeSize());
47 }
48
49 // Iteration control
50 public void setInterval(int beg_bci, int end_bci) {
51 if (Assert.ASSERTS_ENABLED) {
52 Assert.that(0 <= beg_bci && beg_bci <= _method.getCodeSize(), "illegal beg_bci");
53 Assert.that(0 <= end_bci && end_bci <= _method.getCodeSize(), "illegal end_bci");
54 }
55 // setup of iteration pointers
56 _bci = beg_bci;
57 _next_bci = beg_bci;
58 _end_bci = end_bci;
59 }
60
61 public void setStart(int beg_bci) {
62 setInterval(beg_bci, (int) _method.getCodeSize());
63 }
64
65 // Iteration
66 public int next() {
67 int code;
68 // set reading position
69 _bci = _next_bci;
70 if (isLastBytecode()) {
71 // indicate end of bytecode stream
72 code = Bytecodes._illegal;
73 } else {
74 // get bytecode
75 int rawCode = Bytecodes.codeAt(_method, _bci);
76 code = 0; // Make javac happy
77 try {
78 code = Bytecodes.javaCode(rawCode);
79 } catch (AssertionFailure e) {
80 e.printStackTrace();
81 Assert.that(false, "Failure occurred at bci " + _bci + " in method " + _method.externalNameAndSignature());
82 }
83
84 // set next bytecode position
85 //
86 int l = Bytecodes.lengthFor(code);
87 if (l == 0) l = Bytecodes.lengthAt(_method, _bci);
88 _next_bci += l;
89 if (Assert.ASSERTS_ENABLED) {
90 Assert.that(_bci < _next_bci, "length must be > 0");
91 }
92 // set attributes
93 _is_wide = false;
94 // check for special (uncommon) cases
95 if (code == Bytecodes._wide) {
96 code = _method.getBytecodeOrBPAt(_bci + 1);
97 _is_wide = true;
98 }
99 if (Assert.ASSERTS_ENABLED) {
100 Assert.that(Bytecodes.isJavaCode(code), "sanity check");
101 }
102 }
103 _code = code;
104 return _code;
105 }
106
107 // Stream attributes
108 public Method method() { return _method; }
109 public int bci() { return _bci; }
110 public int nextBCI() { return _next_bci; }
111 public int endBCI() { return _end_bci; }
112 public int code() { return _code; }
113 public boolean isWide() { return _is_wide; }
114 public boolean isActiveBreakpoint() { return Bytecodes.isActiveBreakpointAt(_method, _bci); }
115 public boolean isLastBytecode() { return _next_bci >= _end_bci; }
116
117 // State changes
118 public void setNextBCI(int bci) {
119 if (Assert.ASSERTS_ENABLED) {
120 Assert.that(0 <= bci && bci <= _method.getCodeSize(), "illegal bci");
121 }
122 _next_bci = bci;
123 }
124
125 // Bytecode-specific attributes
126 public int dest() { return bci() + _method.getBytecodeShortArg(bci() + 1); }
127 public int dest_w() { return bci() + _method.getBytecodeIntArg(bci() + 1); }
128
129 // Unsigned indices, widening
130 public int getIndex() { return (isWide())
131 ? (_method.getBytecodeShortArg(bci() + 2) & 0xFFFF)
132 : (_method.getBytecodeOrBPAt(bci() + 1) & 0xFF); }
133 public int getIndexU1() { return _method.getBytecodeOrBPAt(bci() + 1) & 0xFF; }
134 public int getIndexU2() { return _method.getBytecodeShortArg(bci() + 1) & 0xFFFF; }
135 public int getIndexU4() { return _method.getNativeIntArg(bci() + 1); }
136 public boolean hasIndexU4() { return code() == Bytecodes._invokedynamic; }
137
138 public int getIndexU1Cpcache() { return _method.getBytecodeOrBPAt(bci() + 1) & 0xFF; }
139 public int getIndexU2Cpcache() { return _method.getNativeShortArg(bci() + 1) & 0xFFFF; }
140
141 // Fetch at absolute BCI (for manual parsing of certain bytecodes)
142 public int codeAt(int bci) {
143 return _method.getBytecodeOrBPAt(bci);
144 }
145 }