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 /*

  * Copyright 1998-2008 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

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  */

 // 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.*).

 class constantPoolCacheOopDesc: public oopDesc {

   friend class VMStructs;

  private:

   int             _length;

   constantPoolOop _constant_pool;                // the corresponding constant pool

   // If true, safe for concurrent GC processing,

   // Set unconditionally in constantPoolCacheKlass::allocate()

   volatile bool        _is_conc_safe;

   // Sizing

   debug_only(friend class ClassVerifier;)

   int length() const                             { return _length; }

   void set_length(int length)                    { _length = length; }

   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; }

   // GC support

   // If the _length field has not been set, the size of the

   // constantPoolCache cannot be correctly calculated.

   bool is_conc_safe()                            { return _is_conc_safe; }

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

   // 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);

 };