1 /*
   2  * Copyright (c) 1999, 2012, 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_VM_CI_CISTREAMS_HPP
  26 #define SHARE_VM_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   void assert_wide(bool require_wide) const {
  74     if (require_wide)
  75          { assert(is_wide(),  "must be a wide instruction"); }
  76     else { assert(!is_wide(), "must not be a wide instruction"); }
  77   }
  78 
  79   Bytecode bytecode() const { return Bytecode(this, _bc_start); }
  80   Bytecode next_bytecode() const { return Bytecode(this, _pc); }
  81 
  82 public:
  83   // End-Of-Bytecodes
  84   static Bytecodes::Code EOBC() {
  85     return Bytecodes::_illegal;
  86   }
  87 
  88   ciBytecodeStream(ciMethod* m) {
  89     reset_to_method(m);
  90   }
  91 
  92   ciBytecodeStream() {
  93     reset_to_method(NULL);
  94   }
  95 
  96   ciMethod* method() const { return _method; }
  97 
  98   void reset_to_method(ciMethod* m) {
  99     _method = m;
 100     if (m == NULL) {
 101       _holder = NULL;
 102       reset(NULL, 0);
 103     } else {
 104       _holder = m->holder();
 105       reset(m->code(), m->code_size());
 106     }
 107   }
 108 
 109   void reset_to_bci( int bci );
 110 
 111   // Force the iterator to report a certain bci.
 112   void force_bci(int bci);
 113 
 114   void set_max_bci( int max ) {
 115     _end = _start + max;
 116   }
 117 
 118   address cur_bcp() const       { return _bc_start; }  // Returns bcp to current instruction
 119   int next_bci() const          { return _pc - _start; }
 120   int cur_bci() const           { return _bc_start - _start; }
 121   int instruction_size() const  { return _pc - _bc_start; }
 122 
 123   Bytecodes::Code cur_bc() const{ return check_java(_bc); }
 124   Bytecodes::Code cur_bc_raw() const { return check_defined(_raw_bc); }
 125   Bytecodes::Code next_bc()     { return Bytecodes::java_code((Bytecodes::Code)* _pc); }
 126 
 127   // Return current ByteCode and increment PC to next bytecode, skipping all
 128   // intermediate constants.  Returns EOBC at end.
 129   // Expected usage:
 130   //     ciBytecodeStream iter(m);
 131   //     while (iter.next() != ciBytecodeStream::EOBC()) { ... }
 132   Bytecodes::Code next() {
 133     _bc_start = _pc;                        // Capture start of bc
 134     if( _pc >= _end ) return EOBC();        // End-Of-Bytecodes
 135 
 136     // Fetch Java bytecode
 137     // All rewritten bytecodes maintain the size of original bytecode.
 138     _bc = Bytecodes::java_code(_raw_bc = (Bytecodes::Code)*_pc);
 139     int csize = Bytecodes::length_for(_bc); // Expected size
 140     _pc += csize;                           // Bump PC past bytecode
 141     if (csize == 0) {
 142       _bc = next_wide_or_table(_bc);
 143     }
 144     return check_java(_bc);
 145   }
 146 
 147   bool is_wide() const { return ( _pc == _was_wide ); }
 148 
 149   // Does this instruction contain an index which refes into the CP cache?
 150   bool has_cache_index() const { return Bytecodes::uses_cp_cache(cur_bc_raw()); }
 151 
 152   bool has_optional_appendix() { return Bytecodes::has_optional_appendix(cur_bc_raw()); }
 153 
 154   int get_index_u1() const {
 155     return bytecode().get_index_u1(cur_bc_raw());
 156   }
 157 
 158   int get_index_u1_cpcache() const {
 159     return bytecode().get_index_u1_cpcache(cur_bc_raw());
 160   }
 161 
 162   // Get a byte index following this bytecode.
 163   // If prefixed with a wide bytecode, get a wide index.
 164   int get_index() const {
 165     assert(!has_cache_index(), "else use cpcache variant");
 166     return (_pc == _was_wide)   // was widened?
 167       ? get_index_u2(true)      // yes, return wide index
 168       : get_index_u1();         // no, return narrow index
 169   }
 170 
 171   // Get 2-byte index (byte swapping depending on which bytecode)
 172   int get_index_u2(bool is_wide = false) const {
 173     return bytecode().get_index_u2(cur_bc_raw(), is_wide);
 174   }
 175 
 176   // Get 2-byte index in native byte order.  (Rewriter::rewrite makes these.)
 177   int get_index_u2_cpcache() const {
 178     return bytecode().get_index_u2_cpcache(cur_bc_raw());
 179   }
 180 
 181   // Get 4-byte index, for invokedynamic.
 182   int get_index_u4() const {
 183     return bytecode().get_index_u4(cur_bc_raw());
 184   }
 185 
 186   bool has_index_u4() const {
 187     return bytecode().has_index_u4(cur_bc_raw());
 188   }
 189 
 190   // Get dimensions byte (multinewarray)
 191   int get_dimensions() const { return *(unsigned char*)(_pc-1); }
 192 
 193   // Sign-extended index byte/short, no widening
 194   int get_constant_u1()                     const { return bytecode().get_constant_u1(instruction_size()-1, cur_bc_raw()); }
 195   int get_constant_u2(bool is_wide = false) const { return bytecode().get_constant_u2(instruction_size()-2, cur_bc_raw(), is_wide); }
 196 
 197   // Get a byte signed constant for "iinc".  Invalid for other bytecodes.
 198   // If prefixed with a wide bytecode, get a wide constant
 199   int get_iinc_con() const {return (_pc==_was_wide) ? (jshort) get_constant_u2(true) : (jbyte) get_constant_u1();}
 200 
 201   // 2-byte branch offset from current pc
 202   int get_dest() const {
 203     return cur_bci() + bytecode().get_offset_s2(cur_bc_raw());
 204   }
 205 
 206   // 2-byte branch offset from next pc
 207   int next_get_dest() const {
 208     assert(_pc < _end, "");
 209     return next_bci() + next_bytecode().get_offset_s2(Bytecodes::_ifeq);
 210   }
 211 
 212   // 4-byte branch offset from current pc
 213   int get_far_dest() const {
 214     return cur_bci() + bytecode().get_offset_s4(cur_bc_raw());
 215   }
 216 
 217   // For a lookup or switch table, return target destination
 218   int get_int_table( int index ) const {
 219     return Bytes::get_Java_u4((address)&_table_base[index]); }
 220 
 221   // For tableswitch - get length of offset part
 222   int get_tableswitch_length()  { return get_int_table(2)-get_int_table(1)+1; }
 223 
 224   int get_dest_table( int index ) const {
 225     return cur_bci() + get_int_table(index); }
 226 
 227   // --- Constant pool access ---
 228   int get_constant_raw_index() const;
 229   int get_constant_pool_index() const;
 230   int get_constant_cache_index() const;
 231   int get_field_index();
 232   int get_method_index();
 233 
 234   // If this bytecode is a new, newarray, multianewarray, instanceof,
 235   // or checkcast, get the referenced klass.
 236   ciKlass* get_klass(bool& will_link);
 237   int get_klass_index() const;
 238 
 239   // If this bytecode is one of the ldc variants, get the referenced
 240   // constant.  Do not attempt to resolve it, since that would require
 241   // execution of Java code.  If it is not resolved, return an unloaded
 242   // object (ciConstant.as_object()->is_loaded() == false).
 243   ciConstant get_constant();
 244   constantTag get_constant_pool_tag(int index) const;
 245 
 246   // True if the klass-using bytecode points to an unresolved klass
 247   bool is_unresolved_klass() const {
 248     constantTag tag = get_constant_pool_tag(get_klass_index());
 249     return tag.is_unresolved_klass();
 250   }
 251 
 252   // If this bytecode is one of get_field, get_static, put_field,
 253   // or put_static, get the referenced field.
 254   ciField* get_field(bool& will_link);
 255 
 256   ciInstanceKlass* get_declared_field_holder();
 257   int      get_field_holder_index();
 258   int      get_field_signature_index();
 259 
 260   ciMethod*     get_method(bool& will_link, ciSignature* *declared_signature_result);
 261   bool          has_appendix();
 262   ciObject*     get_appendix();
 263   bool          has_method_type();
 264   ciMethodType* get_method_type();
 265   ciKlass*      get_declared_method_holder();
 266   int           get_method_holder_index();
 267   int           get_method_signature_index();
 268 
 269   // Get the resolved references arrays from the constant pool
 270   ciObjArray* get_resolved_references();
 271 };
 272 
 273 
 274 // ciSignatureStream
 275 //
 276 // The class is used to iterate over the elements of a method signature.
 277 class ciSignatureStream : public StackObj {
 278 private:
 279   ciSignature* _sig;
 280   int          _pos;
 281   // holder is a method's holder
 282   ciKlass*     _holder;
 283 public:
 284   ciSignatureStream(ciSignature* signature, ciKlass* holder = NULL) {
 285     _sig = signature;
 286     _pos = 0;
 287     _holder = holder;
 288   }
 289 
 290   bool at_return_type() { return _pos == _sig->count(); }
 291 
 292   bool is_done() { return _pos > _sig->count(); }
 293 
 294   void next() {
 295     if (_pos <= _sig->count()) {
 296       _pos++;
 297     }
 298   }
 299 
 300   ciType* type() {
 301     if (at_return_type()) {
 302       return _sig->return_type();
 303     } else {
 304       return _sig->type_at(_pos);
 305     }
 306   }
 307 
 308   // next klass in the signature
 309   ciKlass* next_klass() {
 310     ciKlass* sig_k;
 311     if (_holder != NULL) {
 312       sig_k = _holder;
 313       _holder = NULL;
 314     } else {
 315       while (!type()->is_klass()) {
 316         next();
 317       }
 318       assert(!at_return_type(), "passed end of signature");
 319       sig_k = type()->as_klass();
 320       next();
 321     }
 322     return sig_k;
 323   }
 324 };
 325 
 326 
 327 // ciExceptionHandlerStream
 328 //
 329 // The class is used to iterate over the exception handlers of
 330 // a method.
 331 class ciExceptionHandlerStream : public StackObj {
 332 private:
 333   // The method whose handlers we are traversing
 334   ciMethod* _method;
 335 
 336   // Our current position in the list of handlers
 337   int        _pos;
 338   int        _end;
 339 
 340   ciInstanceKlass*  _exception_klass;
 341   int        _bci;
 342   bool       _is_exact;
 343 
 344 public:
 345   ciExceptionHandlerStream(ciMethod* method) {
 346     _method = method;
 347 
 348     // Force loading of method code and handlers.
 349     _method->code();
 350 
 351     _pos = 0;
 352     _end = _method->_handler_count;
 353     _exception_klass = NULL;
 354     _bci    = -1;
 355     _is_exact = false;
 356   }
 357 
 358   ciExceptionHandlerStream(ciMethod* method, int bci,
 359                            ciInstanceKlass* exception_klass = NULL,
 360                            bool is_exact = false) {
 361     _method = method;
 362 
 363     // Force loading of method code and handlers.
 364     _method->code();
 365 
 366     _pos = -1;
 367     _end = _method->_handler_count + 1; // include the rethrow handler
 368     _exception_klass = (exception_klass != NULL && exception_klass->is_loaded()
 369                           ? exception_klass
 370                           : NULL);
 371     _bci = bci;
 372     assert(_bci >= 0, "bci out of range");
 373     _is_exact = is_exact;
 374     next();
 375   }
 376 
 377   // These methods are currently implemented in an odd way.
 378   // Count the number of handlers the iterator has ever produced
 379   // or will ever produce.  Do not include the final rethrow handler.
 380   // That is, a trivial exception handler stream will have a count
 381   // of zero and produce just the rethrow handler.
 382   int count();
 383 
 384   // Count the number of handlers this stream will produce from now on.
 385   // Include the current handler, and the final rethrow handler.
 386   // The remaining count will be zero iff is_done() is true,
 387   int count_remaining();
 388 
 389   bool is_done() {
 390     return (_pos >= _end);
 391   }
 392 
 393   void next() {
 394     _pos++;
 395     if (_bci != -1) {
 396       // We are not iterating over all handlers...
 397       while (!is_done()) {
 398         ciExceptionHandler* handler = _method->_exception_handlers[_pos];
 399         if (handler->is_in_range(_bci)) {
 400           if (handler->is_catch_all()) {
 401             // Found final active catch block.
 402             _end = _pos+1;
 403             return;
 404           } else if (_exception_klass == NULL || !handler->catch_klass()->is_loaded()) {
 405             // We cannot do any type analysis here.  Must conservatively assume
 406             // catch block is reachable.
 407             return;
 408           } else if (_exception_klass->is_subtype_of(handler->catch_klass())) {
 409             // This catch clause will definitely catch the exception.
 410             // Final candidate.
 411             _end = _pos+1;
 412             return;
 413           } else if (!_is_exact &&
 414                      handler->catch_klass()->is_subtype_of(_exception_klass)) {
 415             // This catch block may be reachable.
 416             return;
 417           }
 418         }
 419 
 420         // The catch block was not pertinent.  Go on.
 421         _pos++;
 422       }
 423     } else {
 424       // This is an iteration over all handlers.
 425       return;
 426     }
 427   }
 428 
 429   ciExceptionHandler* handler() {
 430     return _method->_exception_handlers[_pos];
 431   }
 432 };
 433 
 434 
 435 
 436 // Implementation for declarations in bytecode.hpp
 437 Bytecode::Bytecode(const ciBytecodeStream* stream, address bcp): _bcp(bcp != NULL ? bcp : stream->cur_bcp()), _code(Bytecodes::code_at(NULL, addr_at(0))) {}
 438 Bytecode_lookupswitch::Bytecode_lookupswitch(const ciBytecodeStream* stream): Bytecode(stream) { verify(); }
 439 Bytecode_tableswitch::Bytecode_tableswitch(const ciBytecodeStream* stream): Bytecode(stream) { verify(); }
 440 
 441 #endif // SHARE_VM_CI_CISTREAMS_HPP