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 /*

  * Copyright (c) 2010, 2012, 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_GC_IMPLEMENTATION_CONCURRENTMARKSWEEP_PROMOTIONINFO_HPP

 #define SHARE_VM_GC_IMPLEMENTATION_CONCURRENTMARKSWEEP_PROMOTIONINFO_HPP

 #include "gc_implementation/concurrentMarkSweep/freeChunk.hpp"

 #include "memory/allocation.hpp"

 // Forward declarations

 class CompactibleFreeListSpace;

 class PromotedObject VALUE_OBJ_CLASS_SPEC {

  private:

   enum {

     promoted_mask  = right_n_bits(2),   // i.e. 0x3

     displaced_mark = nth_bit(2),        // i.e. 0x4

     next_mask      = ~(right_n_bits(3)) // i.e. ~(0x7)

   };

   // Below, we want _narrow_next in the "higher" 32 bit slot,

   // whose position will depend on endian-ness of the platform.

   // This is so that there is no interference with the

   // cms_free_bit occupying bit position 7 (lsb == 0)

   // when we are using compressed oops; see FreeChunk::is_free().

   // We cannot move the cms_free_bit down because currently

   // biased locking code assumes that age bits are contiguous

   // with the lock bits. Even if that assumption were relaxed,

   // the least position we could move this bit to would be

   // to bit position 3, which would require 16 byte alignment.

   typedef struct {

 #ifdef VM_LITTLE_ENDIAN

     LP64_ONLY(narrowOop _pad;)

               narrowOop _narrow_next;

 #else

               narrowOop _narrow_next;

     LP64_ONLY(narrowOop _pad;)

 #endif

   } Data;

   union {

     intptr_t _next;

     Data     _data;

   };

  public:

   inline PromotedObject* next() const {

     assert(!((FreeChunk*)this)->is_free(), "Error");

     PromotedObject* res;

     if (UseCompressedOops) {

       // The next pointer is a compressed oop stored in the top 32 bits

       res = (PromotedObject*)oopDesc::decode_heap_oop(_data._narrow_next);

     } else {

       res = (PromotedObject*)(_next & next_mask);

     }

     assert(oop(res)->is_oop_or_null(true /* ignore mark word */), "Not an oop?");

     return res;

   }

   inline void setNext(PromotedObject* x) {

     assert(((intptr_t)x & ~next_mask) == 0, "Conflict in bit usage, "

            "or insufficient alignment of objects");

     if (UseCompressedOops) {

       assert(_data._narrow_next == 0, "Overwrite?");

       _data._narrow_next = oopDesc::encode_heap_oop(oop(x));

     } else {

       _next |= (intptr_t)x;

     }

     assert(!((FreeChunk*)this)->is_free(), "Error");

   }

   inline void setPromotedMark() {

     _next |= promoted_mask;

     assert(!((FreeChunk*)this)->is_free(), "Error");

   }

   inline bool hasPromotedMark() const {

     assert(!((FreeChunk*)this)->is_free(), "Error");

     return (_next & promoted_mask) == promoted_mask;

   }

   inline void setDisplacedMark() {

     _next |= displaced_mark;

     assert(!((FreeChunk*)this)->is_free(), "Error");

   }

   inline bool hasDisplacedMark() const {

     assert(!((FreeChunk*)this)->is_free(), "Error");

     return (_next & displaced_mark) != 0;

   }

   inline void clear_next()        {

     _next = 0;

     assert(!((FreeChunk*)this)->is_free(), "Error");

   }

   debug_only(void *next_addr() { return (void *) &_next; })

 };

 class SpoolBlock: public FreeChunk {

   friend class PromotionInfo;

  protected:

   SpoolBlock*  nextSpoolBlock;

   size_t       bufferSize;        // number of usable words in this block

   markOop*     displacedHdr;      // the displaced headers start here

   // Note about bufferSize: it denotes the number of entries available plus 1;

   // legal indices range from 1 through BufferSize - 1.  See the verification

   // code verify() that counts the number of displaced headers spooled.

   size_t computeBufferSize() {

     return (size() * sizeof(HeapWord) - sizeof(*this)) / sizeof(markOop);

   }

  public:

   void init() {

     bufferSize = computeBufferSize();

     displacedHdr = (markOop*)&displacedHdr;

     nextSpoolBlock = NULL;

   }

   void print_on(outputStream* st) const;

   void print() const { print_on(gclog_or_tty); }

 };

 class PromotionInfo VALUE_OBJ_CLASS_SPEC {

   bool            _tracking;      // set if tracking

   CompactibleFreeListSpace* _space; // the space to which this belongs

   PromotedObject* _promoHead;     // head of list of promoted objects

   PromotedObject* _promoTail;     // tail of list of promoted objects

   SpoolBlock*     _spoolHead;     // first spooling block

   SpoolBlock*     _spoolTail;     // last  non-full spooling block or null

   SpoolBlock*     _splice_point;  // when _spoolTail is null, holds list tail

   SpoolBlock*     _spareSpool;    // free spool buffer

   size_t          _firstIndex;    // first active index in

                                   // first spooling block (_spoolHead)

   size_t          _nextIndex;     // last active index + 1 in last

                                   // spooling block (_spoolTail)

  private:

   // ensure that spooling space exists; return true if there is spooling space

   bool ensure_spooling_space_work();

  public:

   PromotionInfo() :

     _tracking(0), _space(NULL),

     _promoHead(NULL), _promoTail(NULL),

     _spoolHead(NULL), _spoolTail(NULL),

     _spareSpool(NULL), _firstIndex(1),

     _nextIndex(1) {}

   bool noPromotions() const {

     assert(_promoHead != NULL || _promoTail == NULL, "list inconsistency");

     return _promoHead == NULL;

   }

   void startTrackingPromotions();

   void stopTrackingPromotions(uint worker_id = 0);

   bool tracking() const          { return _tracking;  }

   void track(PromotedObject* trackOop);      // keep track of a promoted oop

   // The following variant must be used when trackOop is not fully

   // initialized and has a NULL klass:

   void track(PromotedObject* trackOop, Klass* klassOfOop); // keep track of a promoted oop

   void setSpace(CompactibleFreeListSpace* sp) { _space = sp; }

   CompactibleFreeListSpace* space() const     { return _space; }

   markOop nextDisplacedHeader(); // get next header & forward spool pointer

   void    saveDisplacedHeader(markOop hdr);

                                  // save header and forward spool

   inline size_t refillSize() const;

   SpoolBlock* getSpoolBlock();   // return a free spooling block

   inline bool has_spooling_space() {

     return _spoolTail != NULL && _spoolTail->bufferSize > _nextIndex;

   }

   // ensure that spooling space exists

   bool ensure_spooling_space() {

     return has_spooling_space() || ensure_spooling_space_work();

   }

   #define PROMOTED_OOPS_ITERATE_DECL(OopClosureType, nv_suffix)  \

     void promoted_oops_iterate##nv_suffix(OopClosureType* cl);

   ALL_SINCE_SAVE_MARKS_CLOSURES(PROMOTED_OOPS_ITERATE_DECL)

   #undef PROMOTED_OOPS_ITERATE_DECL

   void promoted_oops_iterate(OopsInGenClosure* cl) {

     promoted_oops_iterate_v(cl);

   }

   void verify()  const;

   void reset() {

     _promoHead = NULL;

     _promoTail = NULL;

     _spoolHead = NULL;

     _spoolTail = NULL;

     _spareSpool = NULL;

     _firstIndex = 0;

     _nextIndex = 0;

   }

   void print_on(outputStream* st) const;

   void print_statistics(uint worker_id) const;

 };

 #endif // SHARE_VM_GC_IMPLEMENTATION_CONCURRENTMARKSWEEP_PROMOTIONINFO_HPP