Mercurial > jdk8-mips64-public > hotspot / file revision

 /*

  * Copyright 1997-2005 Sun Microsystems, Inc.  All Rights Reserved.

  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

  *

  * This code is free software; you can redistribute it and/or modify it

  * under the terms of the GNU General Public License version 2 only, as

  * published by the Free Software Foundation.

  *

  * This code is distributed in the hope that it will be useful, but WITHOUT

  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

  * version 2 for more details (a copy is included in the LICENSE file that

  * accompanied this code).

  *

  * You should have received a copy of the GNU General Public License version

  * 2 along with this work; if not, write to the Free Software Foundation,

  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

  *

  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

  * CA 95054 USA or visit www.sun.com if you need additional information or

  * have any questions.

  *

  */

 // A BytecodeStream is used for fast iteration over the bytecodes

 // of a methodOop.

 //

 // Usage:

 //

 // BytecodeStream s(method);

 // Bytecodes::Code c;

 // while ((c = s.next()) >= 0) {

 //   ...

 // }

 //

 // A RawBytecodeStream is a simple version of BytecodeStream.

 // It is used ONLY when we know the bytecodes haven't been rewritten

 // yet, such as in the rewriter or the verifier. Currently only the

 // verifier uses this class.

 class RawBytecodeStream: StackObj {

  protected:

   // stream buffer

   methodHandle    _method;                       // read from method directly

   // reading position

   int             _bci;                          // bci if current bytecode

   int             _next_bci;                     // bci of next bytecode

   int             _end_bci;                      // bci after the current iteration interval

   // last bytecode read

   Bytecodes::Code _code;

   bool            _is_wide;

  public:

   // Construction

   RawBytecodeStream(methodHandle method) : _method(method) {

     set_interval(0, _method->code_size());

   }

   // Iteration control

   void set_interval(int beg_bci, int end_bci) {

     // iterate over the interval [beg_bci, end_bci)

     assert(0 <= beg_bci && beg_bci <= method()->code_size(), "illegal beg_bci");

     assert(0 <= end_bci && end_bci <= method()->code_size(), "illegal end_bci");

     // setup of iteration pointers

     _bci      = beg_bci;

     _next_bci = beg_bci;

     _end_bci  = end_bci;

   }

   void set_start   (int beg_bci) {

     set_interval(beg_bci, _method->code_size());

   }

   // Iteration

   // Use raw_next() rather than next() for faster method reference

   Bytecodes::Code raw_next() {

     Bytecodes::Code code;

     // set reading position

     _bci = _next_bci;

     assert(!is_last_bytecode(), "caller should check is_last_bytecode()");

     address bcp = RawBytecodeStream::bcp();

     code        = Bytecodes::code_or_bp_at(bcp);

     // set next bytecode position

     int l = Bytecodes::length_for(code);

     if (l > 0 && (_bci + l) <= _end_bci) {

       assert(code != Bytecodes::_wide && code != Bytecodes::_tableswitch

              && code != Bytecodes::_lookupswitch, "can't be special bytecode");

       _is_wide = false;

       _next_bci += l;

       _code = code;

       return code;

     } else if (code == Bytecodes::_wide && _bci + 1 >= _end_bci) {

       return Bytecodes::_illegal;

     } else {

       return raw_next_special(code);

     }

   }

   Bytecodes::Code raw_next_special(Bytecodes::Code code);

   // Stream attributes

   methodHandle    method() const                 { return _method; }

   int             bci() const                    { return _bci; }

   int             next_bci() const               { return _next_bci; }

   int             end_bci() const                { return _end_bci; }

   Bytecodes::Code code() const                   { return _code; }

   bool            is_wide() const                { return _is_wide; }

   bool            is_last_bytecode() const       { return _next_bci >= _end_bci; }

   address         bcp() const                    { return method()->code_base() + _bci; }

   address         next_bcp()                     { return method()->code_base() + _next_bci; }

   // State changes

   void            set_next_bci(int bci)          { assert(0 <= bci && bci <= method()->code_size(), "illegal bci"); _next_bci = bci; }

   // Bytecode-specific attributes

   int             dest() const                   { return bci() + (short)Bytes::get_Java_u2(bcp() + 1); }

   int             dest_w() const                 { return bci() + (int  )Bytes::get_Java_u4(bcp() + 1); }

   // Unsigned indices, widening

   int             get_index() const              { return (is_wide()) ? Bytes::get_Java_u2(bcp() + 2) : bcp()[1]; }

   int             get_index_big() const          { return (int)Bytes::get_Java_u2(bcp() + 1);  }

 };

 // In BytecodeStream, non-java bytecodes will be translated into the

 // corresponding java bytecodes.

 class BytecodeStream: public RawBytecodeStream {

  public:

   // Construction

   BytecodeStream(methodHandle method) : RawBytecodeStream(method) { }

   // Iteration

   Bytecodes::Code next() {

     Bytecodes::Code code;

     // set reading position

     _bci = _next_bci;

     if (is_last_bytecode()) {

       // indicate end of bytecode stream

       code = Bytecodes::_illegal;

     } else {

       // get bytecode

       address bcp = BytecodeStream::bcp();

       code        = Bytecodes::java_code_at(bcp);

       // set next bytecode position

       //

       // note that we cannot advance before having the

       // tty bytecode otherwise the stepping is wrong!

       // (carefull: length_for(...) must be used first!)

       int l = Bytecodes::length_for(code);

       if (l == 0) l = Bytecodes::length_at(bcp);

       _next_bci  += l;

       assert(_bci < _next_bci, "length must be > 0");

       // set attributes

       _is_wide      = false;

       // check for special (uncommon) cases

       if (code == Bytecodes::_wide) {

         code = (Bytecodes::Code)bcp[1];

         _is_wide = true;

       }

       assert(Bytecodes::is_java_code(code), "sanity check");

     }

     _code = code;

     return _code;

   }

   bool            is_active_breakpoint() const   { return Bytecodes::is_active_breakpoint_at(bcp()); }

 };