1 /*
2 * Copyright (c) 1997, 2010, 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 // A BytecodeStream is used for fast iteration over the bytecodes
26 // of a methodOop.
27 //
28 // Usage:
29 //
30 // BytecodeStream s(method);
31 // Bytecodes::Code c;
32 // while ((c = s.next()) >= 0) {
33 // ...
34 // }
35
36 // A RawBytecodeStream is a simple version of BytecodeStream.
37 // It is used ONLY when we know the bytecodes haven't been rewritten
38 // yet, such as in the rewriter or the verifier.
39
40 // Here is the common base class for both RawBytecodeStream and BytecodeStream:
41 class BaseBytecodeStream: StackObj {
42 protected:
43 // stream buffer
44 methodHandle _method; // read from method directly
45
46 // reading position
47 int _bci; // bci if current bytecode
48 int _next_bci; // bci of next bytecode
49 int _end_bci; // bci after the current iteration interval
50
51 // last bytecode read
52 Bytecodes::Code _raw_code;
53 bool _is_wide;
54 bool _is_raw; // false in 'cooked' BytecodeStream
55
56 // Construction
57 BaseBytecodeStream(methodHandle method) : _method(method) {
58 set_interval(0, _method->code_size());
59 _is_raw = false;
60 }
61
62 public:
63 // Iteration control
64 void set_interval(int beg_bci, int end_bci) {
65 // iterate over the interval [beg_bci, end_bci)
66 assert(0 <= beg_bci && beg_bci <= method()->code_size(), "illegal beg_bci");
67 assert(0 <= end_bci && end_bci <= method()->code_size(), "illegal end_bci");
68 // setup of iteration pointers
69 _bci = beg_bci;
70 _next_bci = beg_bci;
71 _end_bci = end_bci;
72 }
73 void set_start (int beg_bci) {
74 set_interval(beg_bci, _method->code_size());
75 }
76
77 bool is_raw() const { return _is_raw; }
78
79 // Stream attributes
80 methodHandle method() const { return _method; }
81
82 int bci() const { return _bci; }
83 int next_bci() const { return _next_bci; }
84 int end_bci() const { return _end_bci; }
85
86 Bytecodes::Code raw_code() const { return _raw_code; }
87 bool is_wide() const { return _is_wide; }
88 int instruction_size() const { return (_next_bci - _bci); }
89 bool is_last_bytecode() const { return _next_bci >= _end_bci; }
90
91 address bcp() const { return method()->code_base() + _bci; }
92 Bytecode* bytecode() const { return Bytecode_at(bcp()); }
93
94 // State changes
95 void set_next_bci(int bci) { assert(0 <= bci && bci <= method()->code_size(), "illegal bci"); _next_bci = bci; }
96
97 // Bytecode-specific attributes
98 int dest() const { return bci() + bytecode()->get_offset_s2(raw_code()); }
99 int dest_w() const { return bci() + bytecode()->get_offset_s4(raw_code()); }
100
101 // One-byte indices.
102 int get_index_u1() const { assert_raw_index_size(1); return *(jubyte*)(bcp()+1); }
103
104 protected:
105 void assert_raw_index_size(int size) const NOT_DEBUG_RETURN;
106 void assert_raw_stream(bool want_raw) const NOT_DEBUG_RETURN;
107 };
108
109 class RawBytecodeStream: public BaseBytecodeStream {
110 public:
111 // Construction
112 RawBytecodeStream(methodHandle method) : BaseBytecodeStream(method) {
113 _is_raw = true;
114 }
115
116 public:
117 // Iteration
118 // Use raw_next() rather than next() for faster method reference
119 Bytecodes::Code raw_next() {
120 Bytecodes::Code code;
121 // set reading position
122 _bci = _next_bci;
123 assert(!is_last_bytecode(), "caller should check is_last_bytecode()");
124
125 address bcp = this->bcp();
126 code = Bytecodes::code_or_bp_at(bcp);
127
128 // set next bytecode position
129 int l = Bytecodes::length_for(code);
130 if (l > 0 && (_bci + l) <= _end_bci) {
131 assert(code != Bytecodes::_wide && code != Bytecodes::_tableswitch
132 && code != Bytecodes::_lookupswitch, "can't be special bytecode");
133 _is_wide = false;
134 _next_bci += l;
135 _raw_code = code;
136 return code;
137 } else {
138 return raw_next_special(code);
139 }
140 }
141 Bytecodes::Code raw_next_special(Bytecodes::Code code);
142
143 // Unsigned indices, widening, with no swapping of bytes
144 int get_index() const { return (is_wide()) ? get_index_u2_raw(bcp() + 2) : get_index_u1(); }
145 // Get an unsigned 2-byte index, with no swapping of bytes.
146 int get_index_u2() const { assert(!is_wide(), ""); return get_index_u2_raw(bcp() + 1); }
147
148 private:
149 int get_index_u2_raw(address p) const {
150 assert_raw_index_size(2); assert_raw_stream(true);
151 return Bytes::get_Java_u2(p);
152 }
153 };
154
155 // In BytecodeStream, non-java bytecodes will be translated into the
156 // corresponding java bytecodes.
157
158 class BytecodeStream: public BaseBytecodeStream {
159 Bytecodes::Code _code;
160
161 public:
162 // Construction
163 BytecodeStream(methodHandle method) : BaseBytecodeStream(method) { }
164
165 // Iteration
166 Bytecodes::Code next() {
167 Bytecodes::Code raw_code, code;
168 // set reading position
169 _bci = _next_bci;
170 if (is_last_bytecode()) {
171 // indicate end of bytecode stream
172 raw_code = code = Bytecodes::_illegal;
173 } else {
174 // get bytecode
175 address bcp = this->bcp();
176 raw_code = Bytecodes::code_at(bcp);
177 code = Bytecodes::java_code(raw_code);
178 // set next bytecode position
179 //
180 // note that we cannot advance before having the
181 // tty bytecode otherwise the stepping is wrong!
182 // (carefull: length_for(...) must be used first!)
183 int l = Bytecodes::length_for(code);
184 if (l == 0) l = Bytecodes::length_at(bcp);
185 _next_bci += l;
186 assert(_bci < _next_bci, "length must be > 0");
187 // set attributes
188 _is_wide = false;
189 // check for special (uncommon) cases
190 if (code == Bytecodes::_wide) {
191 raw_code = (Bytecodes::Code)bcp[1];
192 code = raw_code; // wide BCs are always Java-normal
193 _is_wide = true;
194 }
195 assert(Bytecodes::is_java_code(code), "sanity check");
196 }
197 _raw_code = raw_code;
198 _code = code;
199 return _code;
200 }
201
202 bool is_active_breakpoint() const { return Bytecodes::is_active_breakpoint_at(bcp()); }
203 Bytecodes::Code code() const { return _code; }
204
205 // Unsigned indices, widening
206 int get_index() const { return is_wide() ? bytecode()->get_index_u2(raw_code(), true) : get_index_u1(); }
207 // Get an unsigned 2-byte index, swapping the bytes if necessary.
208 int get_index_u2() const { assert_raw_stream(false);
209 return bytecode()->get_index_u2(raw_code(), false); }
210 // Get an unsigned 2-byte index in native order.
211 int get_index_u2_cpcache() const { assert_raw_stream(false);
212 return bytecode()->get_index_u2_cpcache(raw_code()); }
213 int get_index_u4() const { assert_raw_stream(false);
214 return bytecode()->get_index_u4(raw_code()); }
215 bool has_index_u4() const { return bytecode()->has_index_u4(raw_code()); }
216 };