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  private:
 236   void assert_index_size(int required_size) const {
 237 #ifdef ASSERT
 238     int isize = instruction_size() - (is_wide() ? 1 : 0) - 1;
 239     if (isize == 2 &&  cur_bc() == Bytecodes::_iinc)
 240       isize = 1;
 241     else if (isize <= 2)
 242       ;                         // no change
 243     else if (has_giant_index())
 244       isize = 4;
 245     else
 246       isize = 2;
 247     assert(isize = required_size, "wrong index size");
 248 #endif
 249   }
 250 };
 251 
 252 
 253 // ciSignatureStream
 254 //
 255 // The class is used to iterate over the elements of a method signature.
 256 class ciSignatureStream : public StackObj {
 257 private:
 258   ciSignature* _sig;
 259   int    _pos;
 260 public:
 261   ciSignatureStream(ciSignature* signature) {
 262     _sig = signature;
 263     _pos = 0;
 264   }
 265 
 266   bool at_return_type() { return _pos == _sig->count(); }
 267 
 268   bool is_done() { return _pos > _sig->count(); }
 269 
 270   void next() {
 271     if (_pos <= _sig->count()) {
 272       _pos++;
 273     }
 274   }
 275 
 276   ciType* type() {
 277     if (at_return_type()) {
 278       return _sig->return_type();
 279     } else {
 280       return _sig->type_at(_pos);
 281     }
 282   }
 283 };
 284 
 285 
 286 // ciExceptionHandlerStream
 287 //
 288 // The class is used to iterate over the exception handlers of
 289 // a method.
 290 class ciExceptionHandlerStream : public StackObj {
 291 private:
 292   // The method whose handlers we are traversing
 293   ciMethod* _method;
 294 
 295   // Our current position in the list of handlers
 296   int        _pos;
 297   int        _end;
 298 
 299   ciInstanceKlass*  _exception_klass;
 300   int        _bci;
 301   bool       _is_exact;
 302 
 303 public:
 304   ciExceptionHandlerStream(ciMethod* method) {
 305     _method = method;
 306 
 307     // Force loading of method code and handlers.
 308     _method->code();
 309 
 310     _pos = 0;
 311     _end = _method->_handler_count;
 312     _exception_klass = NULL;
 313     _bci    = -1;
 314     _is_exact = false;
 315   }
 316 
 317   ciExceptionHandlerStream(ciMethod* method, int bci,
 318                            ciInstanceKlass* exception_klass = NULL,
 319                            bool is_exact = false) {
 320     _method = method;
 321 
 322     // Force loading of method code and handlers.
 323     _method->code();
 324 
 325     _pos = -1;
 326     _end = _method->_handler_count + 1; // include the rethrow handler
 327     _exception_klass = (exception_klass != NULL && exception_klass->is_loaded()
 328                           ? exception_klass
 329                           : NULL);
 330     _bci = bci;
 331     assert(_bci >= 0, "bci out of range");
 332     _is_exact = is_exact;
 333     next();
 334   }
 335 
 336   // These methods are currently implemented in an odd way.
 337   // Count the number of handlers the iterator has ever produced
 338   // or will ever produce.  Do not include the final rethrow handler.
 339   // That is, a trivial exception handler stream will have a count
 340   // of zero and produce just the rethrow handler.
 341   int count();
 342 
 343   // Count the number of handlers this stream will produce from now on.
 344   // Include the current handler, and the final rethrow handler.
 345   // The remaining count will be zero iff is_done() is true,
 346   int count_remaining();
 347 
 348   bool is_done() {
 349     return (_pos >= _end);
 350   }
 351 
 352   void next() {
 353     _pos++;
 354     if (_bci != -1) {
 355       // We are not iterating over all handlers...
 356       while (!is_done()) {
 357         ciExceptionHandler* handler = _method->_exception_handlers[_pos];
 358         if (handler->is_in_range(_bci)) {
 359           if (handler->is_catch_all()) {
 360             // Found final active catch block.
 361             _end = _pos+1;
 362             return;
 363           } else if (_exception_klass == NULL || !handler->catch_klass()->is_loaded()) {
 364             // We cannot do any type analysis here.  Must conservatively assume
 365             // catch block is reachable.
 366             return;
 367           } else if (_exception_klass->is_subtype_of(handler->catch_klass())) {
 368             // This catch clause will definitely catch the exception.
 369             // Final candidate.
 370             _end = _pos+1;
 371             return;
 372           } else if (!_is_exact &&
 373                      handler->catch_klass()->is_subtype_of(_exception_klass)) {
 374             // This catch block may be reachable.
 375             return;
 376           }
 377         }
 378 
 379         // The catch block was not pertinent.  Go on.
 380         _pos++;
 381       }
 382     } else {
 383       // This is an iteration over all handlers.
 384       return;
 385     }
 386   }
 387 
 388   ciExceptionHandler* handler() {
 389     return _method->_exception_handlers[_pos];
 390   }
 391 };