/*

 * 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.

 *

 *

 */

// An constMethodOop represents portions of a Java method which

// do not vary.

//

// Memory layout (each line represents a word). Note that most

// applications load thousands of methods, so keeping the size of this

// structure small has a big impact on footprint.

//

// |------------------------------------------------------|

// | header                                               |

// | klass                                                |

// |------------------------------------------------------|

// | fingerprint 1                                        |

// | fingerprint 2                                        |

// | method                         (oop)                 |

// | stackmap_data                  (oop)                 |

// | exception_table                (oop)                 |

// | constMethod_size                                     |

// | interp_kind  | flags    | code_size                  |

// | name index              | signature index            |

// | method_idnum            | generic_signature_index    |

// |------------------------------------------------------|

// |                                                      |

// | byte codes                                           |

// |                                                      |

// |------------------------------------------------------|

// | compressed linenumber table                          |

// |  (see class CompressedLineNumberReadStream)          |

// |  (note that length is unknown until decompressed)    |

// |  (access flags bit tells whether table is present)   |

// |  (indexed from start of constMethodOop)              |

// |  (elements not necessarily sorted!)                  |

// |------------------------------------------------------|

// | localvariable table elements + length (length last)  |

// |  (length is u2, elements are 6-tuples of u2)         |

// |  (see class LocalVariableTableElement)               |

// |  (access flags bit tells whether table is present)   |

// |  (indexed from end of contMethodOop)                 |

// |------------------------------------------------------|

// | checked exceptions elements + length (length last)   |

// |  (length is u2, elements are u2)                     |

// |  (see class CheckedExceptionElement)                 |

// |  (access flags bit tells whether table is present)   |

// |  (indexed from end of constMethodOop)                |

// |------------------------------------------------------|

// Utitily class decribing elements in checked exceptions table inlined in methodOop.

class CheckedExceptionElement VALUE_OBJ_CLASS_SPEC {

 public:

  u2 class_cp_index;

};

// Utitily class decribing elements in local variable table inlined in methodOop.

class LocalVariableTableElement VALUE_OBJ_CLASS_SPEC {

 public:

  u2 start_bci;

  u2 length;

  u2 name_cp_index;

  u2 descriptor_cp_index;

  u2 signature_cp_index;

  u2 slot;

};

class constMethodOopDesc : public oopDesc {

  friend class constMethodKlass;

  friend class VMStructs;

private:

  enum {

    _has_linenumber_table = 1,

    _has_checked_exceptions = 2,

    _has_localvariable_table = 4

  };

  // Bit vector of signature

  // Callers interpret 0=not initialized yet and

  // -1=too many args to fix, must parse the slow way.

  // The real initial value is special to account for nonatomicity of 64 bit

  // loads and stores.  This value may updated and read without a lock by

  // multiple threads, so is volatile.

  volatile uint64_t _fingerprint;

  volatile bool     _is_conc_safe; // if true, safe for concurrent GC processing

public:

  oop* oop_block_beg() const { return adr_method(); }

  oop* oop_block_end() const { return adr_exception_table() + 1; }

private:

  //

  // The oop block.  See comment in klass.hpp before making changes.

  //

  // Backpointer to non-const methodOop (needed for some JVMTI operations)

  methodOop         _method;

  // Raw stackmap data for the method

  typeArrayOop      _stackmap_data;

  // The exception handler table. 4-tuples of ints [start_pc, end_pc,

  // handler_pc, catch_type index] For methods with no exceptions the

  // table is pointing to Universe::the_empty_int_array

  typeArrayOop      _exception_table;

  //

  // End of the oop block.

  //

  int               _constMethod_size;

  jbyte             _interpreter_kind;

  jbyte             _flags;

  // Size of Java bytecodes allocated immediately after methodOop.

  u2                _code_size;

  u2                _name_index;                 // Method name (index in constant pool)

  u2                _signature_index;            // Method signature (index in constant pool)

  u2                _method_idnum;               // unique identification number for the method within the class

                                                 // initially corresponds to the index into the methods array.

                                                 // but this may change with redefinition

  u2                _generic_signature_index;    // Generic signature (index in constant pool, 0 if absent)

public:

  // Inlined tables

  void set_inlined_tables_length(int checked_exceptions_len,

                                 int compressed_line_number_size,

                                 int localvariable_table_len);

  bool has_linenumber_table() const

    { return (_flags & _has_linenumber_table) != 0; }

  bool has_checked_exceptions() const

    { return (_flags & _has_checked_exceptions) != 0; }

  bool has_localvariable_table() const

    { return (_flags & _has_localvariable_table) != 0; }

  void set_interpreter_kind(int kind)      { _interpreter_kind = kind; }

  int  interpreter_kind(void) const        { return _interpreter_kind; }

  // backpointer to non-const methodOop

  methodOop method() const                 { return _method; }

  void set_method(methodOop m)             { oop_store_without_check((oop*)&_method, (oop) m); }

  // stackmap table data

  typeArrayOop stackmap_data() const { return _stackmap_data; }

  void set_stackmap_data(typeArrayOop sd) {

    oop_store_without_check((oop*)&_stackmap_data, (oop)sd);

  }

  bool has_stackmap_table() const { return _stackmap_data != NULL; }

  // exception handler table

  typeArrayOop exception_table() const           { return _exception_table; }

  void set_exception_table(typeArrayOop e)       { oop_store_without_check((oop*) &_exception_table, (oop) e); }

  bool has_exception_handler() const             { return exception_table() != NULL && exception_table()->length() > 0; }

  void init_fingerprint() {

    const uint64_t initval = CONST64(0x8000000000000000);

    _fingerprint = initval;

  }

  uint64_t fingerprint() const                   {

    // Since reads aren't atomic for 64 bits, if any of the high or low order

    // word is the initial value, return 0.  See init_fingerprint for initval.

    uint high_fp = (uint)(_fingerprint >> 32);

    if ((int) _fingerprint == 0 || high_fp == 0x80000000) {

      return 0L;

    } else {

      return _fingerprint;

    }

  }

  uint64_t set_fingerprint(uint64_t new_fingerprint) {

#ifdef ASSERT

    // Assert only valid if complete/valid 64 bit _fingerprint value is read.

    uint64_t oldfp = fingerprint();

#endif // ASSERT

    _fingerprint = new_fingerprint;

    assert(oldfp == 0L || new_fingerprint == oldfp,

           "fingerprint cannot change");

    assert(((new_fingerprint >> 32) != 0x80000000) && (int)new_fingerprint !=0,

           "fingerprint should call init to set initial value");

    return new_fingerprint;

  }

  // name

  int name_index() const                         { return _name_index; }

  void set_name_index(int index)                 { _name_index = index; }

  // signature

  int signature_index() const                    { return _signature_index; }

  void set_signature_index(int index)            { _signature_index = index; }

  // generics support

  int generic_signature_index() const            { return _generic_signature_index; }

  void set_generic_signature_index(int index)    { _generic_signature_index = index; }

  // Sizing

  static int header_size() {

    return sizeof(constMethodOopDesc)/HeapWordSize;

  }

  // Object size needed

  static int object_size(int code_size, int compressed_line_number_size,

                         int local_variable_table_length,

                         int checked_exceptions_length);

  int object_size() const                 { return _constMethod_size; }

  void set_constMethod_size(int size)     { _constMethod_size = size; }

  // Is object parsable by gc

  bool object_is_parsable()               { return object_size() > 0; }

  // code size

  int code_size() const                          { return _code_size; }

  void set_code_size(int size) {

    assert(max_method_code_size < (1 << 16),

           "u2 is too small to hold method code size in general");

    assert(0 <= size && size <= max_method_code_size, "invalid code size");

    _code_size = size;

  }

  // linenumber table - note that length is unknown until decompression,

  // see class CompressedLineNumberReadStream.

  u_char* compressed_linenumber_table() const;         // not preserved by gc

  u2* checked_exceptions_length_addr() const;

  u2* localvariable_table_length_addr() const;

  // checked exceptions

  int checked_exceptions_length() const;

  CheckedExceptionElement* checked_exceptions_start() const;

  // localvariable table

  int localvariable_table_length() const;

  LocalVariableTableElement* localvariable_table_start() const;

  // byte codes

  void    set_code(address code) {

    if (code_size() > 0) {

      memcpy(code_base(), code, code_size());

    }

  }

  address code_base() const            { return (address) (this+1); }

  address code_end() const             { return code_base() + code_size(); }

  bool    contains(address bcp) const  { return code_base() <= bcp

                                                     && bcp < code_end(); }

  // Offset to bytecodes

  static ByteSize codes_offset()

                            { return in_ByteSize(sizeof(constMethodOopDesc)); }

  // interpreter support

  static ByteSize exception_table_offset()

               { return byte_offset_of(constMethodOopDesc, _exception_table); }

  // Garbage collection support

  oop*  adr_method() const             { return (oop*)&_method;          }

  oop*  adr_stackmap_data() const      { return (oop*)&_stackmap_data;   }

  oop*  adr_exception_table() const    { return (oop*)&_exception_table; }

  bool is_conc_safe() { return _is_conc_safe; }

  void set_is_conc_safe(bool v) { _is_conc_safe = v; }

  // Unique id for the method

  static const u2 MAX_IDNUM;

  static const u2 UNSET_IDNUM;

  u2 method_idnum() const                        { return _method_idnum; }

  void set_method_idnum(u2 idnum)                { _method_idnum = idnum; }

private:

  // Since the size of the compressed line number table is unknown, the

  // offsets of the other variable sized sections are computed backwards

  // from the end of the constMethodOop.

  // First byte after constMethodOop

  address constMethod_end() const

                          { return (address)((oop*)this + _constMethod_size); }

  // Last short in constMethodOop

  u2* last_u2_element() const

                                         { return (u2*)constMethod_end() - 1; }

};