1 /*
2 * Copyright (c) 1999, 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 // 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 next_wide_or_table(Bytecodes::Code); // Handle _wide & complicated inline table
36
37 static Bytecodes::Code check_java(Bytecodes::Code c) {
38 assert(Bytecodes::is_java_code(c), "should not return _fast bytecodes");
39 return c;
40 }
41
42 static Bytecodes::Code check_defined(Bytecodes::Code c) {
43 assert(Bytecodes::is_defined(c), "");
44 return c;
45 }
46
47 ciMethod* _method; // the method
48 ciInstanceKlass* _holder;
49 ciCPCache* _cpcache;
50 address _bc_start; // Start of current bytecode for table
51 address _was_wide; // Address past last wide bytecode
52 jint* _table_base; // Aligned start of last table or switch
53
54 address _start; // Start of bytecodes
55 address _end; // Past end of bytecodes
56 address _pc; // Current PC
57 Bytecodes::Code _bc; // Current bytecode
58 Bytecodes::Code _raw_bc; // Current bytecode, raw form
59
60 void reset( address base, unsigned int size ) {
61 _bc_start =_was_wide = 0;
62 _start = _pc = base; _end = base + size;
63 _cpcache = NULL;
64 }
65
66 void assert_wide(bool require_wide) const {
67 if (require_wide)
68 { assert(is_wide(), "must be a wide instruction"); }
69 else { assert(!is_wide(), "must not be a wide instruction"); }
70 }
71
72 Bytecode* bytecode() const { return Bytecode_at(_bc_start); }
73 Bytecode* next_bytecode() const { return Bytecode_at(_pc); }
74
75 public:
76 // End-Of-Bytecodes
77 static Bytecodes::Code EOBC() {
78 return Bytecodes::_illegal;
79 }
80
81 ciBytecodeStream(ciMethod* m) {
82 reset_to_method(m);
83 }
84
85 ciBytecodeStream() {
86 reset_to_method(NULL);
87 }
88
89 ciMethod* method() const { return _method; }
90
91 void reset_to_method(ciMethod* m) {
92 _method = m;
93 if (m == NULL) {
94 _holder = NULL;
95 reset(NULL, 0);
96 } else {
97 _holder = m->holder();
98 reset(m->code(), m->code_size());
99 }
100 }
101
102 void reset_to_bci( int bci );
103
104 // Force the iterator to report a certain bci.
105 void force_bci(int bci);
106
107 void set_max_bci( int max ) {
108 _end = _start + max;
109 }
110
111 address cur_bcp() const { return _bc_start; } // Returns bcp to current instruction
112 int next_bci() const { return _pc - _start; }
113 int cur_bci() const { return _bc_start - _start; }
114 int instruction_size() const { return _pc - _bc_start; }
115
116 Bytecodes::Code cur_bc() const{ return check_java(_bc); }
117 Bytecodes::Code cur_bc_raw() const { return check_defined(_raw_bc); }
118 Bytecodes::Code next_bc() { return Bytecodes::java_code((Bytecodes::Code)* _pc); }
119
120 // Return current ByteCode and increment PC to next bytecode, skipping all
121 // intermediate constants. Returns EOBC at end.
122 // Expected usage:
123 // while( (bc = iter.next()) != EOBC() ) { ... }
124 Bytecodes::Code next() {
125 _bc_start = _pc; // Capture start of bc
126 if( _pc >= _end ) return EOBC(); // End-Of-Bytecodes
127
128 // Fetch Java bytecode
129 // All rewritten bytecodes maintain the size of original bytecode.
130 _bc = Bytecodes::java_code(_raw_bc = (Bytecodes::Code)*_pc);
131 int csize = Bytecodes::length_for(_bc); // Expected size
132 _pc += csize; // Bump PC past bytecode
133 if (csize == 0) {
134 _bc = next_wide_or_table(_bc);
135 }
136 return check_java(_bc);
137 }
138
139 bool is_wide() const { return ( _pc == _was_wide ); }
140
141 // Does this instruction contain an index which refes into the CP cache?
142 bool has_cache_index() const { return Bytecodes::uses_cp_cache(cur_bc_raw()); }
143
144 int get_index_u1() const {
145 return bytecode()->get_index_u1(cur_bc_raw());
146 }
147
148 int get_index_u1_cpcache() const {
149 return bytecode()->get_index_u1_cpcache(cur_bc_raw());
150 }
151
152 // Get a byte index following this bytecode.
153 // If prefixed with a wide bytecode, get a wide index.
154 int get_index() const {
155 assert(!has_cache_index(), "else use cpcache variant");
156 return (_pc == _was_wide) // was widened?
157 ? get_index_u2(true) // yes, return wide index
158 : get_index_u1(); // no, return narrow index
159 }
160
161 // Get 2-byte index (byte swapping depending on which bytecode)
162 int get_index_u2(bool is_wide = false) const {
163 return bytecode()->get_index_u2(cur_bc_raw(), is_wide);
164 }
165
166 // Get 2-byte index in native byte order. (Rewriter::rewrite makes these.)
167 int get_index_u2_cpcache() const {
168 return bytecode()->get_index_u2_cpcache(cur_bc_raw());
169 }
170
171 // Get 4-byte index, for invokedynamic.
172 int get_index_u4() const {
173 return bytecode()->get_index_u4(cur_bc_raw());
174 }
175
176 bool has_index_u4() const {
177 return bytecode()->has_index_u4(cur_bc_raw());
178 }
179
180 // Get dimensions byte (multinewarray)
181 int get_dimensions() const { return *(unsigned char*)(_pc-1); }
182
183 // Sign-extended index byte/short, no widening
184 int get_constant_u1() const { return bytecode()->get_constant_u1(instruction_size()-1, cur_bc_raw()); }
185 int get_constant_u2(bool is_wide = false) const { return bytecode()->get_constant_u2(instruction_size()-2, cur_bc_raw(), is_wide); }
186
187 // Get a byte signed constant for "iinc". Invalid for other bytecodes.
188 // If prefixed with a wide bytecode, get a wide constant
189 int get_iinc_con() const {return (_pc==_was_wide) ? (jshort) get_constant_u2(true) : (jbyte) get_constant_u1();}
190
191 // 2-byte branch offset from current pc
192 int get_dest() const {
193 return cur_bci() + bytecode()->get_offset_s2(cur_bc_raw());
194 }
195
196 // 2-byte branch offset from next pc
197 int next_get_dest() const {
198 assert(_pc < _end, "");
199 return next_bci() + next_bytecode()->get_offset_s2(Bytecodes::_ifeq);
200 }
201
202 // 4-byte branch offset from current pc
203 int get_far_dest() const {
204 return cur_bci() + bytecode()->get_offset_s4(cur_bc_raw());
205 }
206
207 // For a lookup or switch table, return target destination
208 int get_int_table( int index ) const {
209 return Bytes::get_Java_u4((address)&_table_base[index]); }
210
211 // For tableswitch - get length of offset part
212 int get_tableswitch_length() { return get_int_table(2)-get_int_table(1)+1; }
213
214 int get_dest_table( int index ) const {
215 return cur_bci() + get_int_table(index); }
216
217 // --- Constant pool access ---
218 int get_constant_raw_index() const;
219 int get_constant_pool_index() const;
220 int get_constant_cache_index() const;
221 int get_field_index();
222 int get_method_index();
223
224 // If this bytecode is a new, newarray, multianewarray, instanceof,
225 // or checkcast, get the referenced klass.
226 ciKlass* get_klass(bool& will_link);
227 int get_klass_index() const;
228
229 // If this bytecode is one of the ldc variants, get the referenced
230 // constant. Do not attempt to resolve it, since that would require
231 // execution of Java code. If it is not resolved, return an unloaded
232 // object (ciConstant.as_object()->is_loaded() == false).
233 ciConstant get_constant();
234 constantTag get_constant_pool_tag(int index) const;
235
236 // True if the klass-using bytecode points to an unresolved klass
237 bool is_unresolved_klass() const {
238 constantTag tag = get_constant_pool_tag(get_klass_index());
239 return tag.is_unresolved_klass();
240 }
241
242 // If this bytecode is one of get_field, get_static, put_field,
243 // or put_static, get the referenced field.
244 ciField* get_field(bool& will_link);
245
246 ciInstanceKlass* get_declared_field_holder();
247 int get_field_holder_index();
248 int get_field_signature_index();
249
250 // If this is a method invocation bytecode, get the invoked method.
251 ciMethod* get_method(bool& will_link);
252 ciKlass* get_declared_method_holder();
253 int get_method_holder_index();
254 int get_method_signature_index();
255
256 ciCPCache* get_cpcache() const;
257 ciCallSite* get_call_site();
258 };
259
260
261 // ciSignatureStream
262 //
263 // The class is used to iterate over the elements of a method signature.
264 class ciSignatureStream : public StackObj {
265 private:
266 ciSignature* _sig;
267 int _pos;
268 public:
269 ciSignatureStream(ciSignature* signature) {
270 _sig = signature;
271 _pos = 0;
272 }
273
274 bool at_return_type() { return _pos == _sig->count(); }
275
276 bool is_done() { return _pos > _sig->count(); }
277
278 void next() {
279 if (_pos <= _sig->count()) {
280 _pos++;
281 }
282 }
283
284 ciType* type() {
285 if (at_return_type()) {
286 return _sig->return_type();
287 } else {
288 return _sig->type_at(_pos);
289 }
290 }
291 };
292
293
294 // ciExceptionHandlerStream
295 //
296 // The class is used to iterate over the exception handlers of
297 // a method.
298 class ciExceptionHandlerStream : public StackObj {
299 private:
300 // The method whose handlers we are traversing
301 ciMethod* _method;
302
303 // Our current position in the list of handlers
304 int _pos;
305 int _end;
306
307 ciInstanceKlass* _exception_klass;
308 int _bci;
309 bool _is_exact;
310
311 public:
312 ciExceptionHandlerStream(ciMethod* method) {
313 _method = method;
314
315 // Force loading of method code and handlers.
316 _method->code();
317
318 _pos = 0;
319 _end = _method->_handler_count;
320 _exception_klass = NULL;
321 _bci = -1;
322 _is_exact = false;
323 }
324
325 ciExceptionHandlerStream(ciMethod* method, int bci,
326 ciInstanceKlass* exception_klass = NULL,
327 bool is_exact = false) {
328 _method = method;
329
330 // Force loading of method code and handlers.
331 _method->code();
332
333 _pos = -1;
334 _end = _method->_handler_count + 1; // include the rethrow handler
335 _exception_klass = (exception_klass != NULL && exception_klass->is_loaded()
336 ? exception_klass
337 : NULL);
338 _bci = bci;
339 assert(_bci >= 0, "bci out of range");
340 _is_exact = is_exact;
341 next();
342 }
343
344 // These methods are currently implemented in an odd way.
345 // Count the number of handlers the iterator has ever produced
346 // or will ever produce. Do not include the final rethrow handler.
347 // That is, a trivial exception handler stream will have a count
348 // of zero and produce just the rethrow handler.
349 int count();
350
351 // Count the number of handlers this stream will produce from now on.
352 // Include the current handler, and the final rethrow handler.
353 // The remaining count will be zero iff is_done() is true,
354 int count_remaining();
355
356 bool is_done() {
357 return (_pos >= _end);
358 }
359
360 void next() {
361 _pos++;
362 if (_bci != -1) {
363 // We are not iterating over all handlers...
364 while (!is_done()) {
365 ciExceptionHandler* handler = _method->_exception_handlers[_pos];
366 if (handler->is_in_range(_bci)) {
367 if (handler->is_catch_all()) {
368 // Found final active catch block.
369 _end = _pos+1;
370 return;
371 } else if (_exception_klass == NULL || !handler->catch_klass()->is_loaded()) {
372 // We cannot do any type analysis here. Must conservatively assume
373 // catch block is reachable.
374 return;
375 } else if (_exception_klass->is_subtype_of(handler->catch_klass())) {
376 // This catch clause will definitely catch the exception.
377 // Final candidate.
378 _end = _pos+1;
379 return;
380 } else if (!_is_exact &&
381 handler->catch_klass()->is_subtype_of(_exception_klass)) {
382 // This catch block may be reachable.
383 return;
384 }
385 }
386
387 // The catch block was not pertinent. Go on.
388 _pos++;
389 }
390 } else {
391 // This is an iteration over all handlers.
392 return;
393 }
394 }
395
396 ciExceptionHandler* handler() {
397 return _method->_exception_handlers[_pos];
398 }
399 };