1 /*
2 * Copyright (c) 1997, 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.
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23 */
24
25 #ifndef SHARE_INTERPRETER_BYTECODESTREAM_HPP
26 #define SHARE_INTERPRETER_BYTECODESTREAM_HPP
27
28 #include "interpreter/bytecode.hpp"
29 #include "memory/allocation.hpp"
30 #include "oops/method.hpp"
31 #include "utilities/bytes.hpp"
32
33 // A BytecodeStream is used for fast iteration over the bytecodes
34 // of a Method*.
35 //
36 // Usage:
37 //
38 // BytecodeStream s(method);
39 // Bytecodes::Code c;
40 // while ((c = s.next()) >= 0) {
41 // ...
42 // }
43
44 // A RawBytecodeStream is a simple version of BytecodeStream.
45 // It is used ONLY when we know the bytecodes haven't been rewritten
46 // yet, such as in the rewriter or the verifier.
47
48 // Here is the common base class for both RawBytecodeStream and BytecodeStream:
49 class BaseBytecodeStream: StackObj {
50 protected:
51 // stream buffer
52 methodHandle _method; // read from method directly
53
54 // reading position
55 int _bci; // bci if current bytecode
56 int _next_bci; // bci of next bytecode
57 int _end_bci; // bci after the current iteration interval
58
59 // last bytecode read
60 Bytecodes::Code _raw_code;
61 bool _is_wide;
62 bool _is_raw; // false in 'cooked' BytecodeStream
63
64 // Construction
65 BaseBytecodeStream(const methodHandle& method);
66
67 public:
68 // Iteration control
69 void set_interval(int beg_bci, int end_bci) {
70 // iterate over the interval [beg_bci, end_bci)
71 assert(0 <= beg_bci && beg_bci <= method()->code_size(), "illegal beg_bci");
72 assert(0 <= end_bci && end_bci <= method()->code_size(), "illegal end_bci");
73 // setup of iteration pointers
74 _bci = beg_bci;
75 _next_bci = beg_bci;
76 _end_bci = end_bci;
77 }
78 void set_start (int beg_bci) {
79 set_interval(beg_bci, _method->code_size());
80 }
81
82 bool is_raw() const { return _is_raw; }
83
84 // Stream attributes
85 const methodHandle& method() const { return _method; }
86
87 int bci() const { return _bci; }
88 int next_bci() const { return _next_bci; }
89 int end_bci() const { return _end_bci; }
90
91 Bytecodes::Code raw_code() const { return _raw_code; }
92 bool is_wide() const { return _is_wide; }
93 int instruction_size() const { return (_next_bci - _bci); }
94 bool is_last_bytecode() const { return _next_bci >= _end_bci; }
95
96 address bcp() const { return method()->code_base() + _bci; }
97 Bytecode bytecode() const { return Bytecode(_method(), bcp()); }
98
99 // State changes
100 void set_next_bci(int bci) { assert(0 <= bci && bci <= method()->code_size(), "illegal bci"); _next_bci = bci; }
101
102 // Bytecode-specific attributes
103 int dest() const { return bci() + bytecode().get_offset_s2(raw_code()); }
104 int dest_w() const { return bci() + bytecode().get_offset_s4(raw_code()); }
105
106 // One-byte indices.
107 int get_index_u1() const { assert_raw_index_size(1); return *(jubyte*)(bcp()+1); }
108
109 protected:
110 void assert_raw_index_size(int size) const NOT_DEBUG_RETURN;
111 void assert_raw_stream(bool want_raw) const NOT_DEBUG_RETURN;
112 };
113
114 class RawBytecodeStream: public BaseBytecodeStream {
115 public:
116 // Construction
117 RawBytecodeStream(const methodHandle& method) : BaseBytecodeStream(method) {
118 _is_raw = true;
119 }
120
121 public:
122 // Iteration
123 // Use raw_next() rather than next() for faster method reference
124 Bytecodes::Code raw_next() {
125 Bytecodes::Code code;
126 // set reading position
127 _bci = _next_bci;
128 assert(!is_last_bytecode(), "caller should check is_last_bytecode()");
129
130 address bcp = this->bcp();
131 code = Bytecodes::code_or_bp_at(bcp);
132
133 // set next bytecode position
134 int len = Bytecodes::length_for(code);
135 if (len > 0 && (_bci <= _end_bci - len)) {
136 assert(code != Bytecodes::_wide && code != Bytecodes::_tableswitch
137 && code != Bytecodes::_lookupswitch, "can't be special bytecode");
138 _is_wide = false;
139 _next_bci += len;
140 if (_next_bci <= _bci) { // Check for integer overflow
141 code = Bytecodes::_illegal;
142 }
143 _raw_code = code;
144 return code;
145 } else {
146 return raw_next_special(code);
147 }
148 }
149 Bytecodes::Code raw_next_special(Bytecodes::Code code);
150
151 // Unsigned indices, widening, with no swapping of bytes
152 int get_index() const { return (is_wide()) ? get_index_u2_raw(bcp() + 2) : get_index_u1(); }
153 // Get an unsigned 2-byte index, with no swapping of bytes.
154 int get_index_u2() const { assert(!is_wide(), ""); return get_index_u2_raw(bcp() + 1); }
155
156 private:
157 int get_index_u2_raw(address p) const {
158 assert_raw_index_size(2); assert_raw_stream(true);
159 return Bytes::get_Java_u2(p);
160 }
161 };
162
163 // In BytecodeStream, non-java bytecodes will be translated into the
164 // corresponding java bytecodes.
165
166 class BytecodeStream: public BaseBytecodeStream {
167 Bytecodes::Code _code;
168
169 public:
170 // Construction
171 BytecodeStream(const methodHandle& method) : BaseBytecodeStream(method) { }
172
173 BytecodeStream(const methodHandle& method, int bci) : BaseBytecodeStream(method) {
174 set_start(bci);
175 }
176
177 // Iteration
178 Bytecodes::Code next() {
179 Bytecodes::Code raw_code, code;
180 // set reading position
181 _bci = _next_bci;
182 if (is_last_bytecode()) {
183 // indicate end of bytecode stream
184 raw_code = code = Bytecodes::_illegal;
185 } else {
186 // get bytecode
187 address bcp = this->bcp();
188 raw_code = Bytecodes::code_at(_method(), bcp);
189 code = Bytecodes::java_code(raw_code);
190 // set next bytecode position
191 //
192 // note that we cannot advance before having the
193 // tty bytecode otherwise the stepping is wrong!
194 // (carefull: length_for(...) must be used first!)
195 int len = Bytecodes::length_for(code);
196 if (len == 0) len = Bytecodes::length_at(_method(), bcp);
197 if (len <= 0 || (_bci > _end_bci - len) || (_bci - len >= _next_bci)) {
198 raw_code = code = Bytecodes::_illegal;
199 } else {
200 _next_bci += len;
201 assert(_bci < _next_bci, "length must be > 0");
202 // set attributes
203 _is_wide = false;
204 // check for special (uncommon) cases
205 if (code == Bytecodes::_wide) {
206 raw_code = (Bytecodes::Code)bcp[1];
207 code = raw_code; // wide BCs are always Java-normal
208 _is_wide = true;
209 }
210 assert(Bytecodes::is_java_code(code), "sanity check");
211 }
212 }
213 _raw_code = raw_code;
214 _code = code;
215 return _code;
216 }
217
218 Bytecodes::Code code() const { return _code; }
219
220 // Unsigned indices, widening
221 int get_index() const { return is_wide() ? bytecode().get_index_u2(raw_code(), true) : get_index_u1(); }
222 // Get an unsigned 2-byte index, swapping the bytes if necessary.
223 int get_index_u2() const { assert_raw_stream(false);
224 return bytecode().get_index_u2(raw_code(), false); }
225 // Get an unsigned 2-byte index in native order.
226 int get_index_u2_cpcache() const { assert_raw_stream(false);
227 return bytecode().get_index_u2_cpcache(raw_code()); }
228 int get_index_u4() const { assert_raw_stream(false);
229 return bytecode().get_index_u4(raw_code()); }
230 bool has_index_u4() const { return bytecode().has_index_u4(raw_code()); }
231 };
232
233 #endif // SHARE_INTERPRETER_BYTECODESTREAM_HPP