1 /*
2 * Copyright 1999-2009 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any questions.
22 *
23 */
24
25 // ciBytecodeStream
26 //
27 // The class is used to iterate over the bytecodes of a method.
28 // It hides the details of constant pool structure/access by
29 // providing accessors for constant pool items. It returns only pure
30 // Java bytecodes; VM-internal _fast bytecodes are translated back to
31 // their original form during iteration.
32 class ciBytecodeStream : StackObj {
33 private:
34 // Handling for the weird bytecodes
35 Bytecodes::Code wide(); // Handle wide bytecode
36 Bytecodes::Code table(Bytecodes::Code); // Handle complicated inline table
37
38 static Bytecodes::Code check_java(Bytecodes::Code c) {
39 assert(Bytecodes::is_java_code(c), "should not return _fast bytecodes");
40 return c;
41 }
42
43 ciMethod* _method; // the method
44 ciInstanceKlass* _holder;
45 address _bc_start; // Start of current bytecode for table
46 address _was_wide; // Address past last wide bytecode
47 jint* _table_base; // Aligned start of last table or switch
48
49 address _start; // Start of bytecodes
50 address _end; // Past end of bytecodes
51 address _pc; // Current PC
52 Bytecodes::Code _bc; // Current bytecode
53
54 void reset( address base, unsigned int size ) {
55 _bc_start =_was_wide = 0;
56 _start = _pc = base; _end = base + size; }
57
58 public:
59 // End-Of-Bytecodes
60 static Bytecodes::Code EOBC() {
61 return Bytecodes::_illegal;
62 }
63
64 ciBytecodeStream(ciMethod* m) {
65 reset_to_method(m);
66 }
67
68 ciBytecodeStream() {
69 reset_to_method(NULL);
70 }
71
72 ciMethod* method() const { return _method; }
73
74 void reset_to_method(ciMethod* m) {
75 _method = m;
76 if (m == NULL) {
77 _holder = NULL;
78 reset(NULL, 0);
79 } else {
80 _holder = m->holder();
81 reset(m->code(), m->code_size());
82 }
83 }
84
85 void reset_to_bci( int bci );
86
87 // Force the iterator to report a certain bci.
88 void force_bci(int bci);
89
90 void set_max_bci( int max ) {
91 _end = _start + max;
92 }
93
94 address cur_bcp() const { return _bc_start; } // Returns bcp to current instruction
95 int next_bci() const { return _pc -_start; }
96 int cur_bci() const { return _bc_start - _start; }
97 int instruction_size() const { return _pc - _bc_start; }
98
99 Bytecodes::Code cur_bc() const{ return check_java(_bc); }
100 Bytecodes::Code next_bc() { return Bytecodes::java_code((Bytecodes::Code)* _pc); }
101
102 // Return current ByteCode and increment PC to next bytecode, skipping all
103 // intermediate constants. Returns EOBC at end.
104 // Expected usage:
105 // while( (bc = iter.next()) != EOBC() ) { ... }
106 Bytecodes::Code next() {
107 _bc_start = _pc; // Capture start of bc
108 if( _pc >= _end ) return EOBC(); // End-Of-Bytecodes
109
110 // Fetch Java bytecode
111 // All rewritten bytecodes maintain the size of original bytecode.
112 _bc = Bytecodes::java_code((Bytecodes::Code)*_pc);
113 int csize = Bytecodes::length_for(_bc); // Expected size
114
115 if( _bc == Bytecodes::_wide ) {
116 _bc=wide(); // Handle wide bytecode
117 } else if( csize == 0 ) {
118 _bc=table(_bc); // Handle inline tables
119 } else {
120 _pc += csize; // Bump PC past bytecode
121 }
122 return check_java(_bc);
123 }
124
125 bool is_wide() const { return ( _pc == _was_wide ); }
126
127 // Get a byte index following this bytecode.
128 // If prefixed with a wide bytecode, get a wide index.
129 int get_index() const {
130 assert_index_size(is_wide() ? 2 : 1);
131 return (_pc == _was_wide) // was widened?
132 ? Bytes::get_Java_u2(_bc_start+2) // yes, return wide index
133 : _bc_start[1]; // no, return narrow index
134 }
135
136 // Get 2-byte index (getfield/putstatic/etc)
137 int get_index_big() const {
138 assert_index_size(2);
139 return Bytes::get_Java_u2(_bc_start+1);
140 }
141
142 // Get 2-byte index (or 4-byte, for invokedynamic)
143 int get_index_int() const {
144 return has_giant_index() ? get_index_giant() : get_index_big();
145 }
146
147 // Get 4-byte index, for invokedynamic.
148 int get_index_giant() const {
149 assert_index_size(4);
150 return Bytes::get_native_u4(_bc_start+1);
151 }
152
153 bool has_giant_index() const { return (cur_bc() == Bytecodes::_invokedynamic); }
154
155 // Get dimensions byte (multinewarray)
156 int get_dimensions() const { return *(unsigned char*)(_pc-1); }
157
158 // Sign-extended index byte/short, no widening
159 int get_byte() const { return (int8_t)(_pc[-1]); }
160 int get_short() const { return (int16_t)Bytes::get_Java_u2(_pc-2); }
161 int get_long() const { return (int32_t)Bytes::get_Java_u4(_pc-4); }
162
163 // Get a byte signed constant for "iinc". Invalid for other bytecodes.
164 // If prefixed with a wide bytecode, get a wide constant
165 int get_iinc_con() const {return (_pc==_was_wide) ? get_short() :get_byte();}
166
167 // 2-byte branch offset from current pc
168 int get_dest( ) const {
169 assert( Bytecodes::length_at(_bc_start) == sizeof(jshort)+1, "get_dest called with bad bytecode" );
170 return _bc_start-_start + (short)Bytes::get_Java_u2(_pc-2);
171 }
172
173 // 2-byte branch offset from next pc
174 int next_get_dest( ) const {
175 address next_bc_start = _pc;
176 assert( _pc < _end, "" );
177 Bytecodes::Code next_bc = (Bytecodes::Code)*_pc;
178 assert( next_bc != Bytecodes::_wide, "");
179 int next_csize = Bytecodes::length_for(next_bc);
180 assert( next_csize != 0, "" );
181 assert( next_bc <= Bytecodes::_jsr_w, "");
182 address next_pc = _pc + next_csize;
183 assert( Bytecodes::length_at(next_bc_start) == sizeof(jshort)+1, "next_get_dest called with bad bytecode" );
184 return next_bc_start-_start + (short)Bytes::get_Java_u2(next_pc-2);
185 }
186
187 // 4-byte branch offset from current pc
188 int get_far_dest( ) const {
189 assert( Bytecodes::length_at(_bc_start) == sizeof(jint)+1, "dest4 called with bad bytecode" );
190 return _bc_start-_start + (int)Bytes::get_Java_u4(_pc-4);
191 }
192
193 // For a lookup or switch table, return target destination
194 int get_int_table( int index ) const {
195 return Bytes::get_Java_u4((address)&_table_base[index]); }
196
197 // For tableswitch - get length of offset part
198 int get_tableswitch_length() { return get_int_table(2)-get_int_table(1)+1; }
199
200 int get_dest_table( int index ) const {
201 return cur_bci() + get_int_table(index); }
202
203 // --- Constant pool access ---
204 int get_constant_index() const;
205 int get_field_index();
206 int get_method_index();
207
208 // If this bytecode is a new, newarray, multianewarray, instanceof,
209 // or checkcast, get the referenced klass.
210 ciKlass* get_klass(bool& will_link);
211 int get_klass_index() const;
212
213 // If this bytecode is one of the ldc variants, get the referenced
214 // constant
215 ciConstant get_constant();
216 // True if the ldc variant points to an unresolved string
217 bool is_unresolved_string() const;
218 // True if the ldc variant points to an unresolved klass
219 bool is_unresolved_klass() const;
220
221 // If this bytecode is one of get_field, get_static, put_field,
222 // or put_static, get the referenced field.
223 ciField* get_field(bool& will_link);
224
225 ciInstanceKlass* get_declared_field_holder();
226 int get_field_holder_index();
227 int get_field_signature_index();
228
229 // If this is a method invocation bytecode, get the invoked method.
230 ciMethod* get_method(bool& will_link);
231 ciKlass* get_declared_method_holder();
232 int get_method_holder_index();
233 int get_method_signature_index();
234
235 ciCPCache* get_cpcache();
236
237 private:
238 void assert_index_size(int required_size) const {
239 #ifdef ASSERT
240 int isize = instruction_size() - (is_wide() ? 1 : 0) - 1;
241 if (isize == 2 && cur_bc() == Bytecodes::_iinc)
242 isize = 1;
243 else if (isize <= 2)
244 ; // no change
245 else if (has_giant_index())
246 isize = 4;
247 else
248 isize = 2;
249 assert(isize = required_size, "wrong index size");
250 #endif
251 }
252 };
253
254
255 // ciSignatureStream
256 //
257 // The class is used to iterate over the elements of a method signature.
258 class ciSignatureStream : public StackObj {
259 private:
260 ciSignature* _sig;
261 int _pos;
262 public:
263 ciSignatureStream(ciSignature* signature) {
264 _sig = signature;
265 _pos = 0;
266 }
267
268 bool at_return_type() { return _pos == _sig->count(); }
269
270 bool is_done() { return _pos > _sig->count(); }
271
272 void next() {
273 if (_pos <= _sig->count()) {
274 _pos++;
275 }
276 }
277
278 ciType* type() {
279 if (at_return_type()) {
280 return _sig->return_type();
281 } else {
282 return _sig->type_at(_pos);
283 }
284 }
285 };
286
287
288 // ciExceptionHandlerStream
289 //
290 // The class is used to iterate over the exception handlers of
291 // a method.
292 class ciExceptionHandlerStream : public StackObj {
293 private:
294 // The method whose handlers we are traversing
295 ciMethod* _method;
296
297 // Our current position in the list of handlers
298 int _pos;
299 int _end;
300
301 ciInstanceKlass* _exception_klass;
302 int _bci;
303 bool _is_exact;
304
305 public:
306 ciExceptionHandlerStream(ciMethod* method) {
307 _method = method;
308
309 // Force loading of method code and handlers.
310 _method->code();
311
312 _pos = 0;
313 _end = _method->_handler_count;
314 _exception_klass = NULL;
315 _bci = -1;
316 _is_exact = false;
317 }
318
319 ciExceptionHandlerStream(ciMethod* method, int bci,
320 ciInstanceKlass* exception_klass = NULL,
321 bool is_exact = false) {
322 _method = method;
323
324 // Force loading of method code and handlers.
325 _method->code();
326
327 _pos = -1;
328 _end = _method->_handler_count + 1; // include the rethrow handler
329 _exception_klass = (exception_klass != NULL && exception_klass->is_loaded()
330 ? exception_klass
331 : NULL);
332 _bci = bci;
333 assert(_bci >= 0, "bci out of range");
334 _is_exact = is_exact;
335 next();
336 }
337
338 // These methods are currently implemented in an odd way.
339 // Count the number of handlers the iterator has ever produced
340 // or will ever produce. Do not include the final rethrow handler.
341 // That is, a trivial exception handler stream will have a count
342 // of zero and produce just the rethrow handler.
343 int count();
344
345 // Count the number of handlers this stream will produce from now on.
346 // Include the current handler, and the final rethrow handler.
347 // The remaining count will be zero iff is_done() is true,
348 int count_remaining();
349
350 bool is_done() {
351 return (_pos >= _end);
352 }
353
354 void next() {
355 _pos++;
356 if (_bci != -1) {
357 // We are not iterating over all handlers...
358 while (!is_done()) {
359 ciExceptionHandler* handler = _method->_exception_handlers[_pos];
360 if (handler->is_in_range(_bci)) {
361 if (handler->is_catch_all()) {
362 // Found final active catch block.
363 _end = _pos+1;
364 return;
365 } else if (_exception_klass == NULL || !handler->catch_klass()->is_loaded()) {
366 // We cannot do any type analysis here. Must conservatively assume
367 // catch block is reachable.
368 return;
369 } else if (_exception_klass->is_subtype_of(handler->catch_klass())) {
370 // This catch clause will definitely catch the exception.
371 // Final candidate.
372 _end = _pos+1;
373 return;
374 } else if (!_is_exact &&
375 handler->catch_klass()->is_subtype_of(_exception_klass)) {
376 // This catch block may be reachable.
377 return;
378 }
379 }
380
381 // The catch block was not pertinent. Go on.
382 _pos++;
383 }
384 } else {
385 // This is an iteration over all handlers.
386 return;
387 }
388 }
389
390 ciExceptionHandler* handler() {
391 return _method->_exception_handlers[_pos];
392 }
393 };