1 /*
  2  * Copyright (c) 1999, 2021, 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 #ifndef SHARE_CI_CISTREAMS_HPP
 26 #define SHARE_CI_CISTREAMS_HPP
 27 
 28 #include "ci/ciClassList.hpp"
 29 #include "ci/ciExceptionHandler.hpp"
 30 #include "ci/ciInstanceKlass.hpp"
 31 #include "ci/ciMethod.hpp"
 32 #include "interpreter/bytecode.hpp"
 33 
 34 // ciBytecodeStream
 35 //
 36 // The class is used to iterate over the bytecodes of a method.
 37 // It hides the details of constant pool structure/access by
 38 // providing accessors for constant pool items.  It returns only pure
 39 // Java bytecodes; VM-internal _fast bytecodes are translated back to
 40 // their original form during iteration.
 41 class ciBytecodeStream : StackObj {
 42 private:
 43   // Handling for the weird bytecodes
 44   Bytecodes::Code next_wide_or_table(Bytecodes::Code); // Handle _wide & complicated inline table
 45 
 46   static Bytecodes::Code check_java(Bytecodes::Code c) {
 47     assert(Bytecodes::is_java_code(c), "should not return _fast bytecodes");
 48     return c;
 49   }
 50 
 51   static Bytecodes::Code check_defined(Bytecodes::Code c) {
 52     assert(Bytecodes::is_defined(c), "");
 53     return c;
 54   }
 55 
 56   ciMethod* _method;           // the method
 57   ciInstanceKlass* _holder;
 58   address _bc_start;            // Start of current bytecode for table
 59   address _was_wide;            // Address past last wide bytecode
 60   jint* _table_base;            // Aligned start of last table or switch
 61 
 62   address _start;                  // Start of bytecodes
 63   address _end;                    // Past end of bytecodes
 64   address _pc;                     // Current PC
 65   Bytecodes::Code _bc;             // Current bytecode
 66   Bytecodes::Code _raw_bc;         // Current bytecode, raw form
 67 
 68   void reset( address base, unsigned int size ) {
 69     _bc_start =_was_wide = 0;
 70     _start = _pc = base; _end = base + size;
 71   }
 72 
 73   Bytecode bytecode() const { return Bytecode(this, _bc_start); }
 74   Bytecode next_bytecode() const { return Bytecode(this, _pc); }
 75 
 76 public:
 77   // End-Of-Bytecodes
 78   static Bytecodes::Code EOBC() {
 79     return Bytecodes::_illegal;
 80   }
 81 
 82   ciBytecodeStream(ciMethod* m) {
 83     reset_to_method(m);
 84   }
 85 
 86   ciBytecodeStream() {
 87     reset_to_method(NULL);
 88   }
 89 
 90   ciMethod* method() const { return _method; }
 91 
 92   void reset_to_method(ciMethod* m) {
 93     _method = m;
 94     if (m == NULL) {
 95       _holder = NULL;
 96       reset(NULL, 0);
 97     } else {
 98       _holder = m->holder();
 99       reset(m->code(), m->code_size());
100     }
101   }
102 
103   void reset_to_bci( int bci );
104 
105   // Force the iterator to report a certain bci.
106   void force_bci(int bci);
107 
108   void set_max_bci( int max ) {
109     _end = _start + max;
110   }
111 
112   address cur_bcp() const       { return _bc_start; }  // Returns bcp to current instruction
113   int next_bci() const          { return _pc - _start; }
114   int cur_bci() const           { return _bc_start - _start; }
115   int instruction_size() const  { return _pc - _bc_start; }
116 
117   Bytecodes::Code cur_bc() const{ return check_java(_bc); }
118   Bytecodes::Code cur_bc_raw() const { return check_defined(_raw_bc); }
119   Bytecodes::Code next_bc()     { return Bytecodes::java_code((Bytecodes::Code)* _pc); }
120 
121   // Return current ByteCode and increment PC to next bytecode, skipping all
122   // intermediate constants.  Returns EOBC at end.
123   // Expected usage:
124   //     ciBytecodeStream iter(m);
125   //     while (iter.next() != ciBytecodeStream::EOBC()) { ... }
126   Bytecodes::Code next() {
127     _bc_start = _pc;                        // Capture start of bc
128     if( _pc >= _end ) return EOBC();        // End-Of-Bytecodes
129 
130     // Fetch Java bytecode
131     // All rewritten bytecodes maintain the size of original bytecode.
132     _bc = Bytecodes::java_code(_raw_bc = (Bytecodes::Code)*_pc);
133     int csize = Bytecodes::length_for(_bc); // Expected size
134     _pc += csize;                           // Bump PC past bytecode
135     if (csize == 0) {
136       _bc = next_wide_or_table(_bc);
137     }
138     return check_java(_bc);
139   }
140 
141   bool is_wide() const { return ( _pc == _was_wide ); }
142 
143   // Does this instruction contain an index which refes into the CP cache?
144   bool has_cache_index() const { return Bytecodes::uses_cp_cache(cur_bc_raw()); }
145 
146   int get_index_u1() const {
147     return bytecode().get_index_u1(cur_bc_raw());
148   }
149 
150   // Get a byte index following this bytecode.
151   // If prefixed with a wide bytecode, get a wide index.
152   int get_index() const {
153     assert(!has_cache_index(), "else use cpcache variant");
154     return (_pc == _was_wide)   // was widened?
155       ? get_index_u2(true)      // yes, return wide index
156       : get_index_u1();         // no, return narrow index
157   }
158 
159   // Get 2-byte index (byte swapping depending on which bytecode)
160   int get_index_u2(bool is_wide = false) const {
161     return bytecode().get_index_u2(cur_bc_raw(), is_wide);
162   }
163 
164   // Get 2-byte index in native byte order.  (Rewriter::rewrite makes these.)
165   int get_index_u2_cpcache() const {
166     return bytecode().get_index_u2_cpcache(cur_bc_raw());
167   }
168 
169   // Get 4-byte index, for invokedynamic.
170   int get_index_u4() const {
171     return bytecode().get_index_u4(cur_bc_raw());
172   }
173 
174   bool has_index_u4() const {
175     return bytecode().has_index_u4(cur_bc_raw());
176   }
177 
178   // Get dimensions byte (multinewarray)
179   int get_dimensions() const { return *(unsigned char*)(_pc-1); }
180 
181   // Sign-extended index byte/short, no widening
182   int get_constant_u1()                     const { return bytecode().get_constant_u1(instruction_size()-1, cur_bc_raw()); }
183   int get_constant_u2(bool is_wide = false) const { return bytecode().get_constant_u2(instruction_size()-2, cur_bc_raw(), is_wide); }
184 
185   // Get a byte signed constant for "iinc".  Invalid for other bytecodes.
186   // If prefixed with a wide bytecode, get a wide constant
187   int get_iinc_con() const {return (_pc==_was_wide) ? (jshort) get_constant_u2(true) : (jbyte) get_constant_u1();}
188 
189   // 2-byte branch offset from current pc
190   int get_dest() const {
191     return cur_bci() + bytecode().get_offset_s2(cur_bc_raw());
192   }
193 
194   // 2-byte branch offset from next pc
195   int next_get_dest() const {
196     assert(_pc < _end, "");
197     return next_bci() + next_bytecode().get_offset_s2(Bytecodes::_ifeq);
198   }
199 
200   // 4-byte branch offset from current pc
201   int get_far_dest() const {
202     return cur_bci() + bytecode().get_offset_s4(cur_bc_raw());
203   }
204 
205   // For a lookup or switch table, return target destination
206   int get_int_table( int index ) const {
207     return Bytes::get_Java_u4((address)&_table_base[index]); }
208 
209   int get_dest_table( int index ) const {
210     return cur_bci() + get_int_table(index); }
211 
212   // --- Constant pool access ---
213   int get_constant_raw_index() const;
214   int get_constant_pool_index() const;
215   int get_field_index();
216   int get_method_index();
217 
218   // If this bytecode is a new, newarray, multianewarray, instanceof,
219   // or checkcast, get the referenced klass.
220   ciKlass* get_klass(bool& will_link);
221   int get_klass_index() const;
222   bool has_Q_signature() const;
223 
224   // If this bytecode is one of the ldc variants, get the referenced
225   // constant.  Do not attempt to resolve it, since that would require
226   // execution of Java code.  If it is not resolved, return an unloaded
227   // object (ciConstant.as_object()->is_loaded() == false).
228   ciConstant get_constant();
229   constantTag get_constant_pool_tag(int index) const;
230 
231   // True if the klass-using bytecode points to an unresolved klass
232   bool is_unresolved_klass() const {
233     constantTag tag = get_constant_pool_tag(get_klass_index());
234     return tag.is_unresolved_klass();
235   }
236 
237   bool is_unresolved_klass_in_error() const {
238     constantTag tag = get_constant_pool_tag(get_klass_index());
239     return tag.is_unresolved_klass_in_error();
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 
249   ciMethod*     get_method(bool& will_link, ciSignature* *declared_signature_result);
250   bool          has_appendix();
251   ciObject*     get_appendix();
252   bool          has_local_signature();
253   ciKlass*      get_declared_method_holder();
254   int           get_method_holder_index();
255   int           get_method_signature_index(const constantPoolHandle& cpool);
256 
257 };
258 
259 
260 // ciSignatureStream
261 //
262 // The class is used to iterate over the elements of a method signature.
263 class ciSignatureStream : public StackObj {
264 private:
265   ciSignature* _sig;
266   int          _pos;
267   // holder is a method's holder
268   ciKlass*     _holder;
269 public:
270   ciSignatureStream(ciSignature* signature, ciKlass* holder = NULL) {
271     _sig = signature;
272     _pos = 0;
273     _holder = holder;
274   }
275 
276   bool at_return_type() { return _pos == _sig->count(); }
277 
278   bool is_done() { return _pos > _sig->count(); }
279 
280   void next() {
281     if (_pos <= _sig->count()) {
282       _pos++;
283     }
284   }
285 
286   ciType* type() {
287     if (at_return_type()) {
288       return _sig->return_type();
289     } else {
290       return _sig->type_at(_pos);
291     }
292   }
293 
294   bool is_null_free() {
295     if (at_return_type()) {
296       return _sig->returns_null_free_inline_type();
297     } else {
298       return _sig->is_null_free_at(_pos);
299     }
300   }
301 
302   // next klass in the signature
303   ciKlass* next_klass() {
304     ciKlass* sig_k;
305     if (_holder != NULL) {
306       sig_k = _holder;
307       _holder = NULL;
308     } else {
309       while (!type()->is_klass()) {
310         next();
311       }
312       assert(!at_return_type(), "passed end of signature");
313       sig_k = type()->as_klass();
314       next();
315     }
316     return sig_k;
317   }
318 };
319 
320 
321 // ciExceptionHandlerStream
322 //
323 // The class is used to iterate over the exception handlers of
324 // a method.
325 class ciExceptionHandlerStream : public StackObj {
326 private:
327   // The method whose handlers we are traversing
328   ciMethod* _method;
329 
330   // Our current position in the list of handlers
331   int        _pos;
332   int        _end;
333 
334   ciInstanceKlass*  _exception_klass;
335   int        _bci;
336   bool       _is_exact;
337 
338 public:
339   ciExceptionHandlerStream(ciMethod* method) {
340     _method = method;
341 
342     // Force loading of method code and handlers.
343     _method->code();
344 
345     _pos = 0;
346     _end = _method->_handler_count;
347     _exception_klass = NULL;
348     _bci    = -1;
349     _is_exact = false;
350   }
351 
352   ciExceptionHandlerStream(ciMethod* method, int bci,
353                            ciInstanceKlass* exception_klass = NULL,
354                            bool is_exact = false) {
355     _method = method;
356 
357     // Force loading of method code and handlers.
358     _method->code();
359 
360     _pos = -1;
361     _end = _method->_handler_count + 1; // include the rethrow handler
362     _exception_klass = (exception_klass != NULL && exception_klass->is_loaded()
363                           ? exception_klass
364                           : NULL);
365     _bci = bci;
366     assert(_bci >= 0, "bci out of range");
367     _is_exact = is_exact;
368     next();
369   }
370 
371   // These methods are currently implemented in an odd way.
372   // Count the number of handlers the iterator has ever produced
373   // or will ever produce.  Do not include the final rethrow handler.
374   // That is, a trivial exception handler stream will have a count
375   // of zero and produce just the rethrow handler.
376   int count();
377 
378   // Count the number of handlers this stream will produce from now on.
379   // Include the current handler, and the final rethrow handler.
380   // The remaining count will be zero iff is_done() is true,
381   int count_remaining();
382 
383   bool is_done() {
384     return (_pos >= _end);
385   }
386 
387   void next() {
388     _pos++;
389     if (_bci != -1) {
390       // We are not iterating over all handlers...
391       while (!is_done()) {
392         ciExceptionHandler* handler = _method->_exception_handlers[_pos];
393         if (handler->is_in_range(_bci)) {
394           if (handler->is_catch_all()) {
395             // Found final active catch block.
396             _end = _pos+1;
397             return;
398           } else if (_exception_klass == NULL || !handler->catch_klass()->is_loaded()) {
399             // We cannot do any type analysis here.  Must conservatively assume
400             // catch block is reachable.
401             return;
402           } else if (_exception_klass->is_subtype_of(handler->catch_klass())) {
403             // This catch clause will definitely catch the exception.
404             // Final candidate.
405             _end = _pos+1;
406             return;
407           } else if (!_is_exact &&
408                      handler->catch_klass()->is_subtype_of(_exception_klass)) {
409             // This catch block may be reachable.
410             return;
411           }
412         }
413 
414         // The catch block was not pertinent.  Go on.
415         _pos++;
416       }
417     } else {
418       // This is an iteration over all handlers.
419       return;
420     }
421   }
422 
423   ciExceptionHandler* handler() {
424     return _method->_exception_handlers[_pos];
425   }
426 };
427 
428 
429 
430 // Implementation for declarations in bytecode.hpp
431 Bytecode::Bytecode(const ciBytecodeStream* stream, address bcp): _bcp(bcp != NULL ? bcp : stream->cur_bcp()), _code(Bytecodes::code_at(NULL, addr_at(0))) {}
432 Bytecode_lookupswitch::Bytecode_lookupswitch(const ciBytecodeStream* stream): Bytecode(stream) { verify(); }
433 Bytecode_tableswitch::Bytecode_tableswitch(const ciBytecodeStream* stream): Bytecode(stream) { verify(); }
434 
435 #endif // SHARE_CI_CISTREAMS_HPP