codeIterator.hpp

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/* Copyright 1994, 1995 LongView Technologies L.L.C. $Revision: 1.32 $ */
/* Copyright (c) 2006, Sun Microsystems, Inc.
All rights reserved.

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the 
following conditions are met:

    * Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
    * Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following 
          disclaimer in the documentation and/or other materials provided with the distribution.
    * Neither the name of Sun Microsystems nor the names of its contributors may be used to endorse or promote products derived 
          from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT 
NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL 
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*/

// CodeIterator is a simple but fast iterator for
// scanning byte code instructions in a methodOop.

class CodeIterator: public StackObj {
 private:
  methodOop method;
  u_char*   current;
  u_char*   end;

  inline void    align();
  inline u_char* align(u_char* p) const                 { return (u_char*) (((int) p + 3) & (~3)); }

 public:
  // Constructor
  CodeIterator(methodOop method, int startBCI = 1);
  CodeIterator(u_char* hp);

  // Advance to next instruction
  // Returns false if we passed the end.
  bool advance() {
    current = next_hp();
    return current < end;
  }

  // accessors
  u_char        byte_at(int offset_from_instruction)    { return current[offset_from_instruction]; }
  oop           oop_at(int offset_from_instruction)     { return *aligned_oop(offset_from_instruction); }
  int           word_at(int offset_from_instruction)    { return (int) *aligned_oop(offset_from_instruction); }

  Bytecodes::Code               code() const            { return Bytecodes::Code(*current); }
  Bytecodes::CodeType           code_type() const       { return Bytecodes::code_type(code()); }
  Bytecodes::Format             format() const          { return Bytecodes::format(code()); }
  Bytecodes::SendType           send() const            { return Bytecodes::send_type(code()); }
  Bytecodes::ArgumentSpec       argumentsType() const   { return Bytecodes::argument_spec(code()); }
  bool                          pop_result() const      { return Bytecodes::pop_tos(code()); }
  Bytecodes::LoopType           loopType() const        { return Bytecodes::loop_type(code()); }
  int                           bci() const;
  int                           next_bci() const;
  u_char*                       hp() const              { return current; }
  u_char*                       next_hp() const;

  // FOR DEOPTIMIZATION
  // Returns the interpreter return point for the current byte code.
  char* interpreter_return_point(bool restore_value = false) const;

  void set_bci(int bci); 

  // returns the location of an aligned oop 
  oop* aligned_oop(int offset_from_instruction) {
    return (oop*) align(current + offset_from_instruction);
  }

  bool is_message_send()   const { return Bytecodes::code_type(code()) == Bytecodes::message_send;   }
  bool is_primitive_call() const { return Bytecodes::code_type(code()) == Bytecodes::primitive_call; }
  bool is_dll_call()       const { return Bytecodes::code_type(code()) == Bytecodes::dll_call;       }

  // Returns the address of the block method if the current butecode is a push closure, NULL otherwise.
  oop* block_method_addr();

  // Returns the block method if the current butecode is a push closure, NULL otherwise.
  methodOop block_method();

  // Customization
  void customize_class_var_code(klassOop to_klass);
  void recustomize_class_var_code(klassOop from_klass, klassOop to_klass);
  void uncustomize_class_var_code(klassOop from_klass);

  void customize_inst_var_code(klassOop to_klass);
  void recustomize_inst_var_code(klassOop from_klass, klassOop to_klass);
  void uncustomize_inst_var_code(klassOop from_klass);

  // Returns the inline cache iff the current instruction is a send
  InterpretedIC*         ic();
  InterpretedPrim_Cache* prim_cache(); 
  InterpretedDLL_Cache*  dll_cache();

  // For byte code manipulation
  void set_code(u_char code) { *current = code; }
};

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