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
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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
BytecodeStream(Method method)44   public BytecodeStream(Method method) {
45     _method = method;
46     setInterval(0, (int) method.getCodeSize());
47   }
48 
49   // Iteration control
setInterval(int beg_bci, int end_bci)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 
setStart(int beg_bci)61   public void setStart(int beg_bci) {
62     setInterval(beg_bci, (int) _method.getCodeSize());
63   }
64 
65   // Iteration
next()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 }
146