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 /*

  * Copyright (c) 1997, 2016, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

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 #ifndef SHARE_VM_INTERPRETER_BYTECODESTREAM_HPP

 #define SHARE_VM_INTERPRETER_BYTECODESTREAM_HPP

 #include "interpreter/bytecode.hpp"

 #include "memory/allocation.hpp"

 #include "oops/method.hpp"

 #include "runtime/handles.inline.hpp"

 #ifdef TARGET_ARCH_x86

 # include "bytes_x86.hpp"

 #endif

 #ifdef TARGET_ARCH_sparc

 # include "bytes_sparc.hpp"

 #endif

 #ifdef TARGET_ARCH_zero

 # include "bytes_zero.hpp"

 #endif

 #ifdef TARGET_ARCH_arm

 # include "bytes_arm.hpp"

 #endif

 #ifdef TARGET_ARCH_ppc

 # include "bytes_ppc.hpp"

 #endif

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

 // of a Method*.

 //

 // 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.

 // Here is the common base class for both RawBytecodeStream and BytecodeStream:

 class BaseBytecodeStream: 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 _raw_code;

   bool            _is_wide;

   bool            _is_raw;                       // false in 'cooked' BytecodeStream

   // Construction

   BaseBytecodeStream(methodHandle method) : _method(method) {

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

     _is_raw = false;

   }

  public:

   // 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());

   }

   bool is_raw() const { return _is_raw; }

   // 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 raw_code() const               { return _raw_code; }

   bool            is_wide() const                { return _is_wide; }

   int             instruction_size() const       { return (_next_bci - _bci); }

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

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

   Bytecode        bytecode() const               { return Bytecode(_method(), bcp()); }

   // 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() + bytecode().get_offset_s2(raw_code()); }

   int             dest_w() const                 { return bci() + bytecode().get_offset_s4(raw_code()); }

   // One-byte indices.

   int             get_index_u1() const           { assert_raw_index_size(1); return *(jubyte*)(bcp()+1); }

  protected:

   void assert_raw_index_size(int size) const NOT_DEBUG_RETURN;

   void assert_raw_stream(bool want_raw) const NOT_DEBUG_RETURN;

 };

 class RawBytecodeStream: public BaseBytecodeStream {

  public:

   // Construction

   RawBytecodeStream(methodHandle method) : BaseBytecodeStream(method) {

     _is_raw = true;

   }

  public:

   // 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 = this->bcp();

     code        = Bytecodes::code_or_bp_at(bcp);

     // set next bytecode position

     int len = Bytecodes::length_for(code);

     if (len > 0 && (_bci <= _end_bci - len)) {

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

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

       _is_wide = false;

       _next_bci += len;

       if (_next_bci <= _bci) { // Check for integer overflow

         code = Bytecodes::_illegal;

       }

       _raw_code = code;

       return code;

     } else {

       return raw_next_special(code);

     }

   }

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

   // Unsigned indices, widening, with no swapping of bytes

   int             get_index() const          { return (is_wide()) ? get_index_u2_raw(bcp() + 2) : get_index_u1(); }

   // Get an unsigned 2-byte index, with no swapping of bytes.

   int             get_index_u2() const       { assert(!is_wide(), ""); return get_index_u2_raw(bcp() + 1);  }

  private:

   int get_index_u2_raw(address p) const {

     assert_raw_index_size(2); assert_raw_stream(true);

     return Bytes::get_Java_u2(p);

   }

 };

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

 // corresponding java bytecodes.

 class BytecodeStream: public BaseBytecodeStream {

   Bytecodes::Code _code;

  public:

   // Construction

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

   // Iteration

   Bytecodes::Code next() {

     Bytecodes::Code raw_code, code;

     // set reading position

     _bci = _next_bci;

     if (is_last_bytecode()) {

       // indicate end of bytecode stream

       raw_code = code = Bytecodes::_illegal;

     } else {

       // get bytecode

       address bcp = this->bcp();

       raw_code = Bytecodes::code_at(_method(), bcp);

       code = Bytecodes::java_code(raw_code);

       // 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 len = Bytecodes::length_for(code);

       if (len == 0) len = Bytecodes::length_at(_method(), bcp);

       if (len <= 0 || (_bci > _end_bci - len) || (_bci - len >= _next_bci)) {

         raw_code = code = Bytecodes::_illegal;

       } else {

         _next_bci  += len;

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

         // set attributes

         _is_wide      = false;

         // check for special (uncommon) cases

         if (code == Bytecodes::_wide) {

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

           code = raw_code;  // wide BCs are always Java-normal

           _is_wide = true;

         }

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

       }

     }

     _raw_code = raw_code;

     _code = code;

     return _code;

   }

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

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

   // Unsigned indices, widening

   int             get_index() const              { return is_wide() ? bytecode().get_index_u2(raw_code(), true) : get_index_u1(); }

   // Get an unsigned 2-byte index, swapping the bytes if necessary.

   int             get_index_u2() const           { assert_raw_stream(false);

                                                    return bytecode().get_index_u2(raw_code(), false); }

   // Get an unsigned 2-byte index in native order.

   int             get_index_u2_cpcache() const   { assert_raw_stream(false);

                                                    return bytecode().get_index_u2_cpcache(raw_code()); }

   int             get_index_u4() const           { assert_raw_stream(false);

                                                    return bytecode().get_index_u4(raw_code()); }

   bool            has_index_u4() const           { return bytecode().has_index_u4(raw_code()); }

 };

 #endif // SHARE_VM_INTERPRETER_BYTECODESTREAM_HPP