/*

 * Copyright 1998-2006 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 ConstantPoolCacheEntry describes an individual entry of the constant

// pool cache. There's 2 principal kinds of entries: field entries for in-

// stance & static field access, and method entries for invokes. Some of

// the entry layout is shared and looks as follows:

//

// bit number |31                0|

// bit length |-8--|-8--|---16----|

// --------------------------------

// _indices   [ b2 | b1 |  index  ]

// _f1        [  entry specific   ]

// _f2        [  entry specific   ]

// _flags     [t|f|vf|v|m|h|unused|field_index] (for field entries)

// bit length |4|1|1 |1|1|0|---7--|----16-----]

// _flags     [t|f|vf|v|m|h|unused|eidx|psze] (for method entries)

// bit length |4|1|1 |1|1|1|---7--|-8--|-8--]

// --------------------------------

//

// with:

// index  = original constant pool index

// b1     = bytecode 1

// b2     = bytecode 2

// psze   = parameters size (method entries only)

// eidx   = interpreter entry index (method entries only)

// field_index = index into field information in holder instanceKlass

//          The index max is 0xffff (max number of fields in constant pool)

//          and is multiplied by (instanceKlass::next_offset) when accessing.

// t      = TosState (see below)

// f      = field is marked final (see below)

// vf     = virtual, final (method entries only : is_vfinal())

// v      = field is volatile (see below)

// m      = invokeinterface used for method in class Object (see below)

// h      = RedefineClasses/Hotswap bit (see below)

//

// The flags after TosState have the following interpretation:

// bit 27: f flag  true if field is marked final

// bit 26: vf flag true if virtual final method

// bit 25: v flag true if field is volatile (only for fields)

// bit 24: m flag true if invokeinterface used for method in class Object

// bit 23: 0 for fields, 1 for methods

//

// The flags 31, 30, 29, 28 together build a 4 bit number 0 to 8 with the

// following mapping to the TosState states:

//

// btos: 0

// ctos: 1

// stos: 2

// itos: 3

// ltos: 4

// ftos: 5

// dtos: 6

// atos: 7

// vtos: 8

//

// Entry specific: field entries:

// _indices = get (b1 section) and put (b2 section) bytecodes, original constant pool index

// _f1      = field holder

// _f2      = field offset in words

// _flags   = field type information, original field index in field holder

//            (field_index section)

//

// Entry specific: method entries:

// _indices = invoke code for f1 (b1 section), invoke code for f2 (b2 section),

//            original constant pool index

// _f1      = method for all but virtual calls, unused by virtual calls

//            (note: for interface calls, which are essentially virtual,

//             contains klassOop for the corresponding interface.

// _f2      = method/vtable index for virtual calls only, unused by all other

//            calls.  The vf flag indicates this is a method pointer not an

//            index.

// _flags   = field type info (f section),

//            virtual final entry (vf),

//            interpreter entry index (eidx section),

//            parameter size (psze section)

//

// Note: invokevirtual & invokespecial bytecodes can share the same constant

//       pool entry and thus the same constant pool cache entry. All invoke

//       bytecodes but invokevirtual use only _f1 and the corresponding b1

//       bytecode, while invokevirtual uses only _f2 and the corresponding

//       b2 bytecode.  The value of _flags is shared for both types of entries.

//

// The fields are volatile so that they are stored in the order written in the

// source code.  The _indices field with the bytecode must be written last.

class ConstantPoolCacheEntry VALUE_OBJ_CLASS_SPEC {

  friend class VMStructs;

 private:

  volatile intx     _indices;  // constant pool index & rewrite bytecodes

  volatile oop      _f1;       // entry specific oop field

  volatile intx     _f2;       // entry specific int/oop field

  volatile intx     _flags;    // flags

#ifdef ASSERT

  bool same_methodOop(oop cur_f1, oop f1);

#endif

  void set_bytecode_1(Bytecodes::Code code);

  void set_bytecode_2(Bytecodes::Code code);

  void set_f1(oop f1)                            {

    oop existing_f1 = _f1; // read once

    assert(existing_f1 == NULL || existing_f1 == f1, "illegal field change");

    oop_store(&_f1, f1);

  }

  void set_f2(intx f2)                           { assert(_f2 == 0    || _f2 == f2, "illegal field change"); _f2 = f2; }

  int as_flags(TosState state, bool is_final, bool is_vfinal, bool is_volatile,

               bool is_method_interface, bool is_method);

  void set_flags(intx flags)                     { _flags = flags; }

 public:

  // specific bit values in flag field

  // Note: the interpreter knows this layout!

  enum FlagBitValues {

    hotSwapBit    = 23,

    methodInterface = 24,

    volatileField = 25,

    vfinalMethod  = 26,

    finalField    = 27

  };

  enum { field_index_mask = 0xFFFF };

  // start of type bits in flags

  // Note: the interpreter knows this layout!

  enum FlagValues {

    tosBits      = 28

  };

  // Initialization

  void set_initial_state(int index);             // sets entry to initial state

  void set_field(                                // sets entry to resolved field state

    Bytecodes::Code get_code,                    // the bytecode used for reading the field

    Bytecodes::Code put_code,                    // the bytecode used for writing the field

    KlassHandle     field_holder,                // the object/klass holding the field

    int             orig_field_index,            // the original field index in the field holder

    int             field_offset,                // the field offset in words in the field holder

    TosState        field_type,                  // the (machine) field type

    bool            is_final,                     // the field is final

    bool            is_volatile                  // the field is volatile

  );

  void set_method(                               // sets entry to resolved method entry

    Bytecodes::Code invoke_code,                 // the bytecode used for invoking the method

    methodHandle    method,                      // the method/prototype if any (NULL, otherwise)

    int             vtable_index                 // the vtable index if any, else negative

  );

  void set_interface_call(

    methodHandle method,                         // Resolved method

    int index                                    // Method index into interface

  );

  void set_parameter_size(int value) {

    assert(parameter_size() == 0 || parameter_size() == value,

           "size must not change");

    // Setting the parameter size by itself is only safe if the

    // current value of _flags is 0, otherwise another thread may have

    // updated it and we don't want to overwrite that value.  Don't

    // bother trying to update it once it's nonzero but always make

    // sure that the final parameter size agrees with what was passed.

    if (_flags == 0) {

      Atomic::cmpxchg_ptr((value & 0xFF), &_flags, 0);

    }

    guarantee(parameter_size() == value, "size must not change");

  }

  // Which bytecode number (1 or 2) in the index field is valid for this bytecode?

  // Returns -1 if neither is valid.

  static int bytecode_number(Bytecodes::Code code) {

    switch (code) {

      case Bytecodes::_getstatic       :    // fall through

      case Bytecodes::_getfield        :    // fall through

      case Bytecodes::_invokespecial   :    // fall through

      case Bytecodes::_invokestatic    :    // fall through

      case Bytecodes::_invokeinterface : return 1;

      case Bytecodes::_putstatic       :    // fall through

      case Bytecodes::_putfield        :    // fall through

      case Bytecodes::_invokevirtual   : return 2;

      default                          : break;

    }

    return -1;

  }

  // Has this bytecode been resolved? Only valid for invokes and get/put field/static.

  bool is_resolved(Bytecodes::Code code) const {

    switch (bytecode_number(code)) {

      case 1:  return (bytecode_1() == code);

      case 2:  return (bytecode_2() == code);

    }

    return false;      // default: not resolved

  }

  // Accessors

  int constant_pool_index() const                { return _indices & 0xFFFF; }

  Bytecodes::Code bytecode_1() const             { return Bytecodes::cast((_indices >> 16) & 0xFF); }

  Bytecodes::Code bytecode_2() const             { return Bytecodes::cast((_indices >> 24) & 0xFF); }

  volatile oop  f1() const                       { return _f1; }

  intx f2() const                                { return _f2; }

  int  field_index() const;

  int  parameter_size() const                    { return _flags & 0xFF; }

  bool is_vfinal() const                         { return ((_flags & (1 << vfinalMethod)) == (1 << vfinalMethod)); }

  bool is_volatile() const                       { return ((_flags & (1 << volatileField)) == (1 << volatileField)); }

  bool is_methodInterface() const                { return ((_flags & (1 << methodInterface)) == (1 << methodInterface)); }

  bool is_byte() const                           { return (((uintx) _flags >> tosBits) == btos); }

  bool is_char() const                           { return (((uintx) _flags >> tosBits) == ctos); }

  bool is_short() const                          { return (((uintx) _flags >> tosBits) == stos); }

  bool is_int() const                            { return (((uintx) _flags >> tosBits) == itos); }

  bool is_long() const                           { return (((uintx) _flags >> tosBits) == ltos); }

  bool is_float() const                          { return (((uintx) _flags >> tosBits) == ftos); }

  bool is_double() const                         { return (((uintx) _flags >> tosBits) == dtos); }

  bool is_object() const                         { return (((uintx) _flags >> tosBits) == atos); }

  TosState flag_state() const                    { assert( ( (_flags >> tosBits) & 0x0F ) < number_of_states, "Invalid state in as_flags");

                                                   return (TosState)((_flags >> tosBits) & 0x0F); }

  // Code generation support

  static WordSize size()                         { return in_WordSize(sizeof(ConstantPoolCacheEntry) / HeapWordSize); }

  static ByteSize indices_offset()               { return byte_offset_of(ConstantPoolCacheEntry, _indices); }

  static ByteSize f1_offset()                    { return byte_offset_of(ConstantPoolCacheEntry, _f1); }

  static ByteSize f2_offset()                    { return byte_offset_of(ConstantPoolCacheEntry, _f2); }

  static ByteSize flags_offset()                 { return byte_offset_of(ConstantPoolCacheEntry, _flags); }

  // GC Support

  void oops_do(void f(oop*));

  void oop_iterate(OopClosure* blk);

  void oop_iterate_m(OopClosure* blk, MemRegion mr);

  void follow_contents();

  void adjust_pointers();

#ifndef SERIALGC

  // Parallel Old

  void follow_contents(ParCompactionManager* cm);

#endif // SERIALGC

  void update_pointers();

  void update_pointers(HeapWord* beg_addr, HeapWord* end_addr);

  // RedefineClasses() API support:

  // If this constantPoolCacheEntry refers to old_method then update it

  // to refer to new_method.

  // trace_name_printed is set to true if the current call has

  // printed the klass name so that other routines in the adjust_*

  // group don't print the klass name.

  bool adjust_method_entry(methodOop old_method, methodOop new_method,

         bool * trace_name_printed);

  bool is_interesting_method_entry(klassOop k);

  bool is_field_entry() const                    { return (_flags & (1 << hotSwapBit)) == 0; }

  bool is_method_entry() const                   { return (_flags & (1 << hotSwapBit)) != 0; }

  // Debugging & Printing

  void print (outputStream* st, int index) const;

  void verify(outputStream* st) const;

  static void verify_tosBits() {

    assert(tosBits == 28, "interpreter now assumes tosBits is 28");

  }

};

// A constant pool cache is a runtime data structure set aside to a constant pool. The cache

// holds interpreter runtime information for all field access and invoke bytecodes. The cache

// is created and initialized before a class is actively used (i.e., initialized), the indivi-

// dual cache entries are filled at resolution (i.e., "link") time (see also: rewriter.*).

  friend class VMStructs;

 private:

  constantPoolOop _constant_pool;                // the corresponding constant pool

  // Sizing

  static int header_size()                       { return sizeof(constantPoolCacheOopDesc) / HeapWordSize; }

  static int object_size(int length)             { return align_object_size(header_size() + length * in_words(ConstantPoolCacheEntry::size())); }

  int object_size()                              { return object_size(length()); }

  // Helpers

  constantPoolOop*        constant_pool_addr()   { return &_constant_pool; }

  ConstantPoolCacheEntry* base() const           { return (ConstantPoolCacheEntry*)((address)this + in_bytes(base_offset())); }

  friend class constantPoolCacheKlass;

 public:

  // Initialization

  void initialize(intArray& inverse_index_map);

  // Accessors

  void set_constant_pool(constantPoolOop pool)   { oop_store_without_check((oop*)&_constant_pool, (oop)pool); }

  constantPoolOop constant_pool() const          { return _constant_pool; }

  ConstantPoolCacheEntry* entry_at(int i) const  { assert(0 <= i && i < length(), "index out of bounds"); return base() + i; }

  // Code generation

  static ByteSize base_offset()                  { return in_ByteSize(sizeof(constantPoolCacheOopDesc)); }

  // RedefineClasses() API support:

  // If any entry of this constantPoolCache points to any of

  // old_methods, replace it with the corresponding new_method.

  // trace_name_printed is set to true if the current call has

  // printed the klass name so that other routines in the adjust_*

  // group don't print the klass name.

  void adjust_method_entries(methodOop* old_methods, methodOop* new_methods,

                             int methods_length, bool * trace_name_printed);

};