Mercurial > jdk8-mips64-public > hotspot / file revision

 /*

  * Copyright 2005-2007 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.

  *

  */

 class ParallelScavengeHeap;

 class PSAdaptiveSizePolicy;

 class PSYoungGen;

 class PSOldGen;

 class PSPermGen;

 class ParCompactionManager;

 class ParallelTaskTerminator;

 class PSParallelCompact;

 class GCTaskManager;

 class GCTaskQueue;

 class PreGCValues;

 class MoveAndUpdateClosure;

 class RefProcTaskExecutor;

 class SpaceInfo

 {

  public:

   MutableSpace* space() const { return _space; }

   // Where the free space will start after the collection.  Valid only after the

   // summary phase completes.

   HeapWord* new_top() const { return _new_top; }

   // Allows new_top to be set.

   HeapWord** new_top_addr() { return &_new_top; }

   // Where the smallest allowable dense prefix ends (used only for perm gen).

   HeapWord* min_dense_prefix() const { return _min_dense_prefix; }

   // Where the dense prefix ends, or the compacted region begins.

   HeapWord* dense_prefix() const { return _dense_prefix; }

   // The start array for the (generation containing the) space, or NULL if there

   // is no start array.

   ObjectStartArray* start_array() const { return _start_array; }

   void set_space(MutableSpace* s)           { _space = s; }

   void set_new_top(HeapWord* addr)          { _new_top = addr; }

   void set_min_dense_prefix(HeapWord* addr) { _min_dense_prefix = addr; }

   void set_dense_prefix(HeapWord* addr)     { _dense_prefix = addr; }

   void set_start_array(ObjectStartArray* s) { _start_array = s; }

  private:

   MutableSpace*     _space;

   HeapWord*         _new_top;

   HeapWord*         _min_dense_prefix;

   HeapWord*         _dense_prefix;

   ObjectStartArray* _start_array;

 };

 class ParallelCompactData

 {

 public:

   // Sizes are in HeapWords, unless indicated otherwise.

   static const size_t Log2ChunkSize;

   static const size_t ChunkSize;

   static const size_t ChunkSizeBytes;

  // Mask for the bits in a size_t to get an offset within a chunk.

   static const size_t ChunkSizeOffsetMask;

  // Mask for the bits in a pointer to get an offset within a chunk.

   static const size_t ChunkAddrOffsetMask;

  // Mask for the bits in a pointer to get the address of the start of a chunk.

   static const size_t ChunkAddrMask;

   static const size_t Log2BlockSize;

   static const size_t BlockSize;

   static const size_t BlockOffsetMask;

   static const size_t BlockMask;

   static const size_t BlocksPerChunk;

   class ChunkData

   {

   public:

     // Destination address of the chunk.

     HeapWord* destination() const { return _destination; }

     // The first chunk containing data destined for this chunk.

     size_t source_chunk() const { return _source_chunk; }

     // The object (if any) starting in this chunk and ending in a different

     // chunk that could not be updated during the main (parallel) compaction

     // phase.  This is different from _partial_obj_addr, which is an object that

     // extends onto a source chunk.  However, the two uses do not overlap in

     // time, so the same field is used to save space.

     HeapWord* deferred_obj_addr() const { return _partial_obj_addr; }

     // The starting address of the partial object extending onto the chunk.

     HeapWord* partial_obj_addr() const { return _partial_obj_addr; }

     // Size of the partial object extending onto the chunk (words).

     size_t partial_obj_size() const { return _partial_obj_size; }

     // Size of live data that lies within this chunk due to objects that start

     // in this chunk (words).  This does not include the partial object

     // extending onto the chunk (if any), or the part of an object that extends

     // onto the next chunk (if any).

     size_t live_obj_size() const { return _dc_and_los & los_mask; }

     // Total live data that lies within the chunk (words).

     size_t data_size() const { return partial_obj_size() + live_obj_size(); }

     // The destination_count is the number of other chunks to which data from

     // this chunk will be copied.  At the end of the summary phase, the valid

     // values of destination_count are

     //

     // 0 - data from the chunk will be compacted completely into itself, or the

     //     chunk is empty.  The chunk can be claimed and then filled.

     // 1 - data from the chunk will be compacted into 1 other chunk; some

     //     data from the chunk may also be compacted into the chunk itself.

     // 2 - data from the chunk will be copied to 2 other chunks.

     //

     // During compaction as chunks are emptied, the destination_count is

     // decremented (atomically) and when it reaches 0, it can be claimed and

     // then filled.

     //

     // A chunk is claimed for processing by atomically changing the

     // destination_count to the claimed value (dc_claimed).  After a chunk has

     // been filled, the destination_count should be set to the completed value

     // (dc_completed).

     inline uint destination_count() const;

     inline uint destination_count_raw() const;

     // The location of the java heap data that corresponds to this chunk.

     inline HeapWord* data_location() const;

     // The highest address referenced by objects in this chunk.

     inline HeapWord* highest_ref() const;

     // Whether this chunk is available to be claimed, has been claimed, or has

     // been completed.

     //

     // Minor subtlety:  claimed() returns true if the chunk is marked

     // completed(), which is desirable since a chunk must be claimed before it

     // can be completed.

     bool available() const { return _dc_and_los < dc_one; }

     bool claimed() const   { return _dc_and_los >= dc_claimed; }

     bool completed() const { return _dc_and_los >= dc_completed; }

     // These are not atomic.

     void set_destination(HeapWord* addr)       { _destination = addr; }

     void set_source_chunk(size_t chunk)        { _source_chunk = chunk; }

     void set_deferred_obj_addr(HeapWord* addr) { _partial_obj_addr = addr; }

     void set_partial_obj_addr(HeapWord* addr)  { _partial_obj_addr = addr; }

     void set_partial_obj_size(size_t words)    {

       _partial_obj_size = (chunk_sz_t) words;

     }

     inline void set_destination_count(uint count);

     inline void set_live_obj_size(size_t words);

     inline void set_data_location(HeapWord* addr);

     inline void set_completed();

     inline bool claim_unsafe();

     // These are atomic.

     inline void add_live_obj(size_t words);

     inline void set_highest_ref(HeapWord* addr);

     inline void decrement_destination_count();

     inline bool claim();

   private:

     // The type used to represent object sizes within a chunk.

     typedef uint chunk_sz_t;

     // Constants for manipulating the _dc_and_los field, which holds both the

     // destination count and live obj size.  The live obj size lives at the

     // least significant end so no masking is necessary when adding.

     static const chunk_sz_t dc_shift;           // Shift amount.

     static const chunk_sz_t dc_mask;            // Mask for destination count.

     static const chunk_sz_t dc_one;             // 1, shifted appropriately.

     static const chunk_sz_t dc_claimed;         // Chunk has been claimed.

     static const chunk_sz_t dc_completed;       // Chunk has been completed.

     static const chunk_sz_t los_mask;           // Mask for live obj size.

     HeapWord*           _destination;

     size_t              _source_chunk;

     HeapWord*           _partial_obj_addr;

     chunk_sz_t          _partial_obj_size;

     chunk_sz_t volatile _dc_and_los;

 #ifdef ASSERT

     // These enable optimizations that are only partially implemented.  Use

     // debug builds to prevent the code fragments from breaking.

     HeapWord*           _data_location;

     HeapWord*           _highest_ref;

 #endif  // #ifdef ASSERT

 #ifdef ASSERT

    public:

     uint            _pushed;    // 0 until chunk is pushed onto a worker's stack

    private:

 #endif

   };

   // 'Blocks' allow shorter sections of the bitmap to be searched.  Each Block

   // holds an offset, which is the amount of live data in the Chunk to the left

   // of the first live object in the Block.  This amount of live data will

   // include any object extending into the block. The first block in

   // a chunk does not include any partial object extending into the

   // the chunk.

   //

   // The offset also encodes the

   // 'parity' of the first 1 bit in the Block:  a positive offset means the

   // first 1 bit marks the start of an object, a negative offset means the first

   // 1 bit marks the end of an object.

   class BlockData

   {

   public:

     typedef short int blk_ofs_t;

     blk_ofs_t offset() const { return _offset >= 0 ? _offset : -_offset; }

     blk_ofs_t raw_offset() const { return _offset; }

     void set_first_is_start_bit(bool v) { _first_is_start_bit = v; }

 #if 0

     // The need for this method was anticipated but it is

     // never actually used.  Do not include it for now.  If

     // it is needed, consider the problem of what is passed

     // as "v".  To avoid warning errors the method set_start_bit_offset()

     // was changed to take a size_t as the parameter and to do the

     // check for the possible overflow.  Doing the cast in these

     // methods better limits the potential problems because of

     // the size of the field to this class.

     void set_raw_offset(blk_ofs_t v) { _offset = v; }

 #endif

     void set_start_bit_offset(size_t val) {

       assert(val >= 0, "sanity");

       _offset = (blk_ofs_t) val;

       assert(val == (size_t) _offset, "Value is too large");

       _first_is_start_bit = true;

     }

     void set_end_bit_offset(size_t val) {

       assert(val >= 0, "sanity");

       _offset = (blk_ofs_t) val;

       assert(val == (size_t) _offset, "Value is too large");

       _offset = - _offset;

       _first_is_start_bit = false;

     }

     bool first_is_start_bit() {

       assert(_set_phase > 0, "Not initialized");

       return _first_is_start_bit;

     }

     bool first_is_end_bit() {

       assert(_set_phase > 0, "Not initialized");

       return !_first_is_start_bit;

     }

   private:

     blk_ofs_t _offset;

     // This is temporary until the mark_bitmap is separated into

     // a start bit array and an end bit array.

     bool      _first_is_start_bit;

 #ifdef ASSERT

     short     _set_phase;

     static short _cur_phase;

   public:

     static void set_cur_phase(short v) { _cur_phase = v; }

 #endif

   };

 public:

   ParallelCompactData();

   bool initialize(MemRegion covered_region);

   size_t chunk_count() const { return _chunk_count; }

   // Convert chunk indices to/from ChunkData pointers.

   inline ChunkData* chunk(size_t chunk_idx) const;

   inline size_t     chunk(const ChunkData* const chunk_ptr) const;

   // Returns true if the given address is contained within the chunk

   bool chunk_contains(size_t chunk_index, HeapWord* addr);

   size_t block_count() const { return _block_count; }

   inline BlockData* block(size_t n) const;

   // Returns true if the given block is in the given chunk.

   static bool chunk_contains_block(size_t chunk_index, size_t block_index);

   void add_obj(HeapWord* addr, size_t len);

   void add_obj(oop p, size_t len) { add_obj((HeapWord*)p, len); }

   // Fill in the chunks covering [beg, end) so that no data moves; i.e., the

   // destination of chunk n is simply the start of chunk n.  The argument beg

   // must be chunk-aligned; end need not be.

   void summarize_dense_prefix(HeapWord* beg, HeapWord* end);

   bool summarize(HeapWord* target_beg, HeapWord* target_end,

                  HeapWord* source_beg, HeapWord* source_end,

                  HeapWord** target_next, HeapWord** source_next = 0);

   void clear();

   void clear_range(size_t beg_chunk, size_t end_chunk);

   void clear_range(HeapWord* beg, HeapWord* end) {

     clear_range(addr_to_chunk_idx(beg), addr_to_chunk_idx(end));

   }

   // Return the number of words between addr and the start of the chunk

   // containing addr.

   inline size_t     chunk_offset(const HeapWord* addr) const;

   // Convert addresses to/from a chunk index or chunk pointer.

   inline size_t     addr_to_chunk_idx(const HeapWord* addr) const;

   inline ChunkData* addr_to_chunk_ptr(const HeapWord* addr) const;

   inline HeapWord*  chunk_to_addr(size_t chunk) const;

   inline HeapWord*  chunk_to_addr(size_t chunk, size_t offset) const;

   inline HeapWord*  chunk_to_addr(const ChunkData* chunk) const;

   inline HeapWord*  chunk_align_down(HeapWord* addr) const;

   inline HeapWord*  chunk_align_up(HeapWord* addr) const;

   inline bool       is_chunk_aligned(HeapWord* addr) const;

   // Analogous to chunk_offset() for blocks.

   size_t     block_offset(const HeapWord* addr) const;

   size_t     addr_to_block_idx(const HeapWord* addr) const;

   size_t     addr_to_block_idx(const oop obj) const {

     return addr_to_block_idx((HeapWord*) obj);

   }

   inline BlockData* addr_to_block_ptr(const HeapWord* addr) const;

   inline HeapWord*  block_to_addr(size_t block) const;

   // Return the address one past the end of the partial object.

   HeapWord* partial_obj_end(size_t chunk_idx) const;

   // Return the new location of the object p after the

   // the compaction.

   HeapWord* calc_new_pointer(HeapWord* addr);

   // Same as calc_new_pointer() using blocks.

   HeapWord* block_calc_new_pointer(HeapWord* addr);

   // Same as calc_new_pointer() using chunks.

   HeapWord* chunk_calc_new_pointer(HeapWord* addr);

   HeapWord* calc_new_pointer(oop p) {

     return calc_new_pointer((HeapWord*) p);

   }

   // Return the updated address for the given klass

   klassOop calc_new_klass(klassOop);

   // Given a block returns true if the partial object for the

   // corresponding chunk ends in the block.  Returns false, otherwise

   // If there is no partial object, returns false.

   bool partial_obj_ends_in_block(size_t block_index);

   // Returns the block index for the block

   static size_t block_idx(BlockData* block);

 #ifdef  ASSERT

   void verify_clear(const PSVirtualSpace* vspace);

   void verify_clear();

 #endif  // #ifdef ASSERT

 private:

   bool initialize_block_data(size_t region_size);

   bool initialize_chunk_data(size_t region_size);

   PSVirtualSpace* create_vspace(size_t count, size_t element_size);

 private:

   HeapWord*       _region_start;

 #ifdef  ASSERT

   HeapWord*       _region_end;

 #endif  // #ifdef ASSERT

   PSVirtualSpace* _chunk_vspace;

   ChunkData*      _chunk_data;

   size_t          _chunk_count;

   PSVirtualSpace* _block_vspace;

   BlockData*      _block_data;

   size_t          _block_count;

 };

 inline uint

 ParallelCompactData::ChunkData::destination_count_raw() const

 {

   return _dc_and_los & dc_mask;

 }

 inline uint

 ParallelCompactData::ChunkData::destination_count() const

 {

   return destination_count_raw() >> dc_shift;

 }

 inline void

 ParallelCompactData::ChunkData::set_destination_count(uint count)

 {

   assert(count <= (dc_completed >> dc_shift), "count too large");

   const chunk_sz_t live_sz = (chunk_sz_t) live_obj_size();

   _dc_and_los = (count << dc_shift) | live_sz;

 }

 inline void ParallelCompactData::ChunkData::set_live_obj_size(size_t words)

 {

   assert(words <= los_mask, "would overflow");

   _dc_and_los = destination_count_raw() | (chunk_sz_t)words;

 }

 inline void ParallelCompactData::ChunkData::decrement_destination_count()

 {

   assert(_dc_and_los < dc_claimed, "already claimed");

   assert(_dc_and_los >= dc_one, "count would go negative");

   Atomic::add((int)dc_mask, (volatile int*)&_dc_and_los);

 }

 inline HeapWord* ParallelCompactData::ChunkData::data_location() const

 {

   DEBUG_ONLY(return _data_location;)

   NOT_DEBUG(return NULL;)

 }

 inline HeapWord* ParallelCompactData::ChunkData::highest_ref() const

 {

   DEBUG_ONLY(return _highest_ref;)

   NOT_DEBUG(return NULL;)

 }

 inline void ParallelCompactData::ChunkData::set_data_location(HeapWord* addr)

 {

   DEBUG_ONLY(_data_location = addr;)

 }

 inline void ParallelCompactData::ChunkData::set_completed()

 {

   assert(claimed(), "must be claimed first");

   _dc_and_los = dc_completed | (chunk_sz_t) live_obj_size();

 }

 // MT-unsafe claiming of a chunk.  Should only be used during single threaded

 // execution.

 inline bool ParallelCompactData::ChunkData::claim_unsafe()

 {

   if (available()) {

     _dc_and_los |= dc_claimed;

     return true;

   }

   return false;

 }

 inline void ParallelCompactData::ChunkData::add_live_obj(size_t words)

 {

   assert(words <= (size_t)los_mask - live_obj_size(), "overflow");

   Atomic::add((int) words, (volatile int*) &_dc_and_los);

 }

 inline void ParallelCompactData::ChunkData::set_highest_ref(HeapWord* addr)

 {

 #ifdef ASSERT

   HeapWord* tmp = _highest_ref;

   while (addr > tmp) {

     tmp = (HeapWord*)Atomic::cmpxchg_ptr(addr, &_highest_ref, tmp);

   }

 #endif  // #ifdef ASSERT

 }

 inline bool ParallelCompactData::ChunkData::claim()

 {

   const int los = (int) live_obj_size();

   const int old = Atomic::cmpxchg(dc_claimed | los,

                                   (volatile int*) &_dc_and_los, los);

   return old == los;

 }

 inline ParallelCompactData::ChunkData*

 ParallelCompactData::chunk(size_t chunk_idx) const

 {

   assert(chunk_idx <= chunk_count(), "bad arg");

   return _chunk_data + chunk_idx;

 }

 inline size_t

 ParallelCompactData::chunk(const ChunkData* const chunk_ptr) const

 {

   assert(chunk_ptr >= _chunk_data, "bad arg");

   assert(chunk_ptr <= _chunk_data + chunk_count(), "bad arg");

   return pointer_delta(chunk_ptr, _chunk_data, sizeof(ChunkData));

 }

 inline ParallelCompactData::BlockData*

 ParallelCompactData::block(size_t n) const {

   assert(n < block_count(), "bad arg");

   return _block_data + n;

 }

 inline size_t

 ParallelCompactData::chunk_offset(const HeapWord* addr) const

 {

   assert(addr >= _region_start, "bad addr");

   assert(addr <= _region_end, "bad addr");

   return (size_t(addr) & ChunkAddrOffsetMask) >> LogHeapWordSize;

 }

 inline size_t

 ParallelCompactData::addr_to_chunk_idx(const HeapWord* addr) const

 {

   assert(addr >= _region_start, "bad addr");

   assert(addr <= _region_end, "bad addr");

   return pointer_delta(addr, _region_start) >> Log2ChunkSize;

 }

 inline ParallelCompactData::ChunkData*

 ParallelCompactData::addr_to_chunk_ptr(const HeapWord* addr) const

 {

   return chunk(addr_to_chunk_idx(addr));

 }

 inline HeapWord*

 ParallelCompactData::chunk_to_addr(size_t chunk) const

 {

   assert(chunk <= _chunk_count, "chunk out of range");

   return _region_start + (chunk << Log2ChunkSize);

 }

 inline HeapWord*

 ParallelCompactData::chunk_to_addr(const ChunkData* chunk) const

 {

   return chunk_to_addr(pointer_delta(chunk, _chunk_data, sizeof(ChunkData)));

 }

 inline HeapWord*

 ParallelCompactData::chunk_to_addr(size_t chunk, size_t offset) const

 {

   assert(chunk <= _chunk_count, "chunk out of range");

   assert(offset < ChunkSize, "offset too big");  // This may be too strict.

   return chunk_to_addr(chunk) + offset;

 }

 inline HeapWord*

 ParallelCompactData::chunk_align_down(HeapWord* addr) const

 {

   assert(addr >= _region_start, "bad addr");

   assert(addr < _region_end + ChunkSize, "bad addr");

   return (HeapWord*)(size_t(addr) & ChunkAddrMask);

 }

 inline HeapWord*

 ParallelCompactData::chunk_align_up(HeapWord* addr) const

 {

   assert(addr >= _region_start, "bad addr");

   assert(addr <= _region_end, "bad addr");

   return chunk_align_down(addr + ChunkSizeOffsetMask);

 }

 inline bool

 ParallelCompactData::is_chunk_aligned(HeapWord* addr) const

 {

   return chunk_offset(addr) == 0;

 }

 inline size_t

 ParallelCompactData::block_offset(const HeapWord* addr) const

 {

   assert(addr >= _region_start, "bad addr");

   assert(addr <= _region_end, "bad addr");

   return pointer_delta(addr, _region_start) & BlockOffsetMask;

 }

 inline size_t

 ParallelCompactData::addr_to_block_idx(const HeapWord* addr) const

 {

   assert(addr >= _region_start, "bad addr");

   assert(addr <= _region_end, "bad addr");

   return pointer_delta(addr, _region_start) >> Log2BlockSize;

 }

 inline ParallelCompactData::BlockData*

 ParallelCompactData::addr_to_block_ptr(const HeapWord* addr) const

 {

   return block(addr_to_block_idx(addr));

 }

 inline HeapWord*

 ParallelCompactData::block_to_addr(size_t block) const

 {

   assert(block < _block_count, "block out of range");

   return _region_start + (block << Log2BlockSize);

 }

 // Abstract closure for use with ParMarkBitMap::iterate(), which will invoke the

 // do_addr() method.

 //

 // The closure is initialized with the number of heap words to process

 // (words_remaining()), and becomes 'full' when it reaches 0.  The do_addr()

 // methods in subclasses should update the total as words are processed.  Since

 // only one subclass actually uses this mechanism to terminate iteration, the

 // default initial value is > 0.  The implementation is here and not in the

 // single subclass that uses it to avoid making is_full() virtual, and thus

 // adding a virtual call per live object.

 class ParMarkBitMapClosure: public StackObj {

  public:

   typedef ParMarkBitMap::idx_t idx_t;

   typedef ParMarkBitMap::IterationStatus IterationStatus;

  public:

   inline ParMarkBitMapClosure(ParMarkBitMap* mbm, ParCompactionManager* cm,

                               size_t words = max_uintx);

   inline ParCompactionManager* compaction_manager() const;

   inline ParMarkBitMap*        bitmap() const;

   inline size_t                words_remaining() const;

   inline bool                  is_full() const;

   inline HeapWord*             source() const;

   inline void                  set_source(HeapWord* addr);

   virtual IterationStatus do_addr(HeapWord* addr, size_t words) = 0;

  protected:

   inline void decrement_words_remaining(size_t words);

  private:

   ParMarkBitMap* const        _bitmap;

   ParCompactionManager* const _compaction_manager;

   DEBUG_ONLY(const size_t     _initial_words_remaining;) // Useful in debugger.

   size_t                      _words_remaining; // Words left to copy.

  protected:

   HeapWord*                   _source;          // Next addr that would be read.

 };

 inline

 ParMarkBitMapClosure::ParMarkBitMapClosure(ParMarkBitMap* bitmap,

                                            ParCompactionManager* cm,

                                            size_t words):

   _bitmap(bitmap), _compaction_manager(cm)

 #ifdef  ASSERT

   , _initial_words_remaining(words)

 #endif

 {

   _words_remaining = words;

   _source = NULL;

 }

 inline ParCompactionManager* ParMarkBitMapClosure::compaction_manager() const {

   return _compaction_manager;

 }

 inline ParMarkBitMap* ParMarkBitMapClosure::bitmap() const {

   return _bitmap;

 }

 inline size_t ParMarkBitMapClosure::words_remaining() const {

   return _words_remaining;

 }

 inline bool ParMarkBitMapClosure::is_full() const {

   return words_remaining() == 0;

 }

 inline HeapWord* ParMarkBitMapClosure::source() const {

   return _source;

 }

 inline void ParMarkBitMapClosure::set_source(HeapWord* addr) {

   _source = addr;

 }

 inline void ParMarkBitMapClosure::decrement_words_remaining(size_t words) {

   assert(_words_remaining >= words, "processed too many words");

   _words_remaining -= words;

 }

 // Closure for updating the block data during the summary phase.

 class BitBlockUpdateClosure: public ParMarkBitMapClosure {

   // ParallelCompactData::BlockData::blk_ofs_t _live_data_left;

   size_t    _live_data_left;

   size_t    _cur_block;

   HeapWord* _chunk_start;

   HeapWord* _chunk_end;

   size_t    _chunk_index;

  public:

   BitBlockUpdateClosure(ParMarkBitMap* mbm,

                         ParCompactionManager* cm,

                         size_t chunk_index);

   size_t cur_block() { return _cur_block; }

   size_t chunk_index() { return _chunk_index; }

   size_t live_data_left() { return _live_data_left; }

   // Returns true the first bit in the current block (cur_block) is

   // a start bit.

   // Returns true if the current block is within the chunk for the closure;

   bool chunk_contains_cur_block();

   // Set the chunk index and related chunk values for

   // a new chunk.

   void reset_chunk(size_t chunk_index);

   virtual IterationStatus do_addr(HeapWord* addr, size_t words);

 };

 class PSParallelCompact : AllStatic {

  public:

   // Convenient access to type names.

   typedef ParMarkBitMap::idx_t idx_t;

   typedef ParallelCompactData::ChunkData ChunkData;

   typedef ParallelCompactData::BlockData BlockData;

   typedef enum {

     perm_space_id, old_space_id, eden_space_id,

     from_space_id, to_space_id, last_space_id

   } SpaceId;

  public:

   // In line closure decls

   //

   class IsAliveClosure: public BoolObjectClosure {

    public:

     void do_object(oop p) { assert(false, "don't call"); }

     bool do_object_b(oop p) { return mark_bitmap()->is_marked(p); }

   };

   class KeepAliveClosure: public OopClosure {

     ParCompactionManager* _compaction_manager;

    public:

     KeepAliveClosure(ParCompactionManager* cm) {

       _compaction_manager = cm;

     }

     void do_oop(oop* p);

   };

   class FollowRootClosure: public OopsInGenClosure{

     ParCompactionManager* _compaction_manager;

    public:

     FollowRootClosure(ParCompactionManager* cm) {

       _compaction_manager = cm;

     }

     void do_oop(oop* p) { follow_root(_compaction_manager, p); }

     virtual const bool do_nmethods() const { return true; }

   };

   class FollowStackClosure: public VoidClosure {

     ParCompactionManager* _compaction_manager;

    public:

     FollowStackClosure(ParCompactionManager* cm) {

       _compaction_manager = cm;

     }

     void do_void() { follow_stack(_compaction_manager); }

   };

   class AdjustPointerClosure: public OopsInGenClosure {

     bool _is_root;

    public:

     AdjustPointerClosure(bool is_root) : _is_root(is_root) {}

     void do_oop(oop* p) { adjust_pointer(p, _is_root); }

   };

   // Closure for verifying update of pointers.  Does not

   // have any side effects.

   class VerifyUpdateClosure: public ParMarkBitMapClosure {

     const MutableSpace* _space; // Is this ever used?

    public:

     VerifyUpdateClosure(ParCompactionManager* cm, const MutableSpace* sp) :

       ParMarkBitMapClosure(PSParallelCompact::mark_bitmap(), cm), _space(sp)

     { }

     virtual IterationStatus do_addr(HeapWord* addr, size_t words);

     const MutableSpace* space() { return _space; }

   };

   // Closure for updating objects altered for debug checking

   class ResetObjectsClosure: public ParMarkBitMapClosure {

    public:

     ResetObjectsClosure(ParCompactionManager* cm):

       ParMarkBitMapClosure(PSParallelCompact::mark_bitmap(), cm)

     { }

     virtual IterationStatus do_addr(HeapWord* addr, size_t words);

   };

   friend class KeepAliveClosure;

   friend class FollowStackClosure;

   friend class AdjustPointerClosure;

   friend class FollowRootClosure;

   friend class instanceKlassKlass;

   friend class RefProcTaskProxy;

   static void mark_and_push_internal(ParCompactionManager* cm, oop* p);

  private:

   static elapsedTimer         _accumulated_time;

   static unsigned int         _total_invocations;

   static unsigned int         _maximum_compaction_gc_num;

   static jlong                _time_of_last_gc;   // ms

   static CollectorCounters*   _counters;

   static ParMarkBitMap        _mark_bitmap;

   static ParallelCompactData  _summary_data;

   static IsAliveClosure       _is_alive_closure;

   static SpaceInfo            _space_info[last_space_id];

   static bool                 _print_phases;

   static AdjustPointerClosure _adjust_root_pointer_closure;

   static AdjustPointerClosure _adjust_pointer_closure;

   // Reference processing (used in ...follow_contents)

   static ReferenceProcessor*  _ref_processor;

   // Updated location of intArrayKlassObj.

   static klassOop _updated_int_array_klass_obj;

   // Values computed at initialization and used by dead_wood_limiter().

   static double _dwl_mean;

   static double _dwl_std_dev;

   static double _dwl_first_term;

   static double _dwl_adjustment;

 #ifdef  ASSERT

   static bool   _dwl_initialized;

 #endif  // #ifdef ASSERT

  private:

   // Closure accessors

   static OopClosure* adjust_pointer_closure() { return (OopClosure*)&_adjust_pointer_closure; }

   static OopClosure* adjust_root_pointer_closure() { return (OopClosure*)&_adjust_root_pointer_closure; }

   static BoolObjectClosure* is_alive_closure() { return (BoolObjectClosure*)&_is_alive_closure; }

   static void initialize_space_info();

   // Return true if details about individual phases should be printed.

   static inline bool print_phases();

   // Clear the marking bitmap and summary data that cover the specified space.

   static void clear_data_covering_space(SpaceId id);

   static void pre_compact(PreGCValues* pre_gc_values);

   static void post_compact();

   // Mark live objects

   static void marking_phase(ParCompactionManager* cm,

                             bool maximum_heap_compaction);

   static void follow_stack(ParCompactionManager* cm);

   static void follow_weak_klass_links(ParCompactionManager* cm);

   static void adjust_pointer(oop* p, bool is_root);

   static void adjust_root_pointer(oop* p) { adjust_pointer(p, true); }

   static void follow_root(ParCompactionManager* cm, oop* p);

   // Compute the dense prefix for the designated space.  This is an experimental

   // implementation currently not used in production.

   static HeapWord* compute_dense_prefix_via_density(const SpaceId id,

                                                     bool maximum_compaction);

   // Methods used to compute the dense prefix.

   // Compute the value of the normal distribution at x = density.  The mean and

   // standard deviation are values saved by initialize_dead_wood_limiter().

   static inline double normal_distribution(double density);

   // Initialize the static vars used by dead_wood_limiter().

   static void initialize_dead_wood_limiter();

   // Return the percentage of space that can be treated as "dead wood" (i.e.,

   // not reclaimed).

   static double dead_wood_limiter(double density, size_t min_percent);

   // Find the first (left-most) chunk in the range [beg, end) that has at least

   // dead_words of dead space to the left.  The argument beg must be the first

   // chunk in the space that is not completely live.

   static ChunkData* dead_wood_limit_chunk(const ChunkData* beg,

                                           const ChunkData* end,

                                           size_t dead_words);

   // Return a pointer to the first chunk in the range [beg, end) that is not

   // completely full.

   static ChunkData* first_dead_space_chunk(const ChunkData* beg,

                                            const ChunkData* end);

   // Return a value indicating the benefit or 'yield' if the compacted region

   // were to start (or equivalently if the dense prefix were to end) at the

   // candidate chunk.  Higher values are better.

   //

   // The value is based on the amount of space reclaimed vs. the costs of (a)

   // updating references in the dense prefix plus (b) copying objects and

   // updating references in the compacted region.

   static inline double reclaimed_ratio(const ChunkData* const candidate,

                                        HeapWord* const bottom,

                                        HeapWord* const top,

                                        HeapWord* const new_top);

   // Compute the dense prefix for the designated space.

   static HeapWord* compute_dense_prefix(const SpaceId id,

                                         bool maximum_compaction);

   // Return true if dead space crosses onto the specified Chunk; bit must be the

   // bit index corresponding to the first word of the Chunk.

   static inline bool dead_space_crosses_boundary(const ChunkData* chunk,

                                                  idx_t bit);

   // Summary phase utility routine to fill dead space (if any) at the dense

   // prefix boundary.  Should only be called if the the dense prefix is

   // non-empty.

   static void fill_dense_prefix_end(SpaceId id);

   static void summarize_spaces_quick();

   static void summarize_space(SpaceId id, bool maximum_compaction);

   static void summary_phase(ParCompactionManager* cm, bool maximum_compaction);

   static bool block_first_offset(size_t block_index, idx_t* block_offset_ptr);

   // Fill in the BlockData

   static void summarize_blocks(ParCompactionManager* cm,

                                SpaceId first_compaction_space_id);

   // The space that is compacted after space_id.

   static SpaceId next_compaction_space_id(SpaceId space_id);

   // Adjust addresses in roots.  Does not adjust addresses in heap.

   static void adjust_roots();

   // Serial code executed in preparation for the compaction phase.

   static void compact_prologue();

   // Move objects to new locations.

   static void compact_perm(ParCompactionManager* cm);

   static void compact();

   // Add available chunks to the stack and draining tasks to the task queue.

   static void enqueue_chunk_draining_tasks(GCTaskQueue* q,

                                            uint parallel_gc_threads);

   // Add dense prefix update tasks to the task queue.

   static void enqueue_dense_prefix_tasks(GCTaskQueue* q,

                                          uint parallel_gc_threads);

   // Add chunk stealing tasks to the task queue.

   static void enqueue_chunk_stealing_tasks(

                                        GCTaskQueue* q,

                                        ParallelTaskTerminator* terminator_ptr,

                                        uint parallel_gc_threads);

   // For debugging only - compacts the old gen serially

   static void compact_serial(ParCompactionManager* cm);

   // If objects are left in eden after a collection, try to move the boundary

   // and absorb them into the old gen.  Returns true if eden was emptied.

   static bool absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,

                                          PSYoungGen* young_gen,

                                          PSOldGen* old_gen);

   // Reset time since last full gc

   static void reset_millis_since_last_gc();

  protected:

 #ifdef VALIDATE_MARK_SWEEP

   static GrowableArray<oop*>*            _root_refs_stack;

   static GrowableArray<oop> *            _live_oops;

   static GrowableArray<oop> *            _live_oops_moved_to;

   static GrowableArray<size_t>*          _live_oops_size;

   static size_t                          _live_oops_index;

   static size_t                          _live_oops_index_at_perm;

   static GrowableArray<oop*>*            _other_refs_stack;

   static GrowableArray<oop*>*            _adjusted_pointers;

   static bool                            _pointer_tracking;

   static bool                            _root_tracking;

   // The following arrays are saved since the time of the last GC and

   // assist in tracking down problems where someone has done an errant

   // store into the heap, usually to an oop that wasn't properly

   // handleized across a GC. If we crash or otherwise fail before the

   // next GC, we can query these arrays to find out the object we had

   // intended to do the store to (assuming it is still alive) and the

   // offset within that object. Covered under RecordMarkSweepCompaction.

   static GrowableArray<HeapWord*> *      _cur_gc_live_oops;

   static GrowableArray<HeapWord*> *      _cur_gc_live_oops_moved_to;

   static GrowableArray<size_t>*          _cur_gc_live_oops_size;

   static GrowableArray<HeapWord*> *      _last_gc_live_oops;

   static GrowableArray<HeapWord*> *      _last_gc_live_oops_moved_to;

   static GrowableArray<size_t>*          _last_gc_live_oops_size;

 #endif

  public:

   class MarkAndPushClosure: public OopClosure {

     ParCompactionManager* _compaction_manager;

    public:

     MarkAndPushClosure(ParCompactionManager* cm) {

       _compaction_manager = cm;

     }

     void do_oop(oop* p) { mark_and_push(_compaction_manager, p); }

     virtual const bool do_nmethods() const { return true; }

   };

   PSParallelCompact();

   // Convenient accessor for Universe::heap().

   static ParallelScavengeHeap* gc_heap() {

     return (ParallelScavengeHeap*)Universe::heap();

   }

   static void invoke(bool maximum_heap_compaction);

   static void invoke_no_policy(bool maximum_heap_compaction);

   static void post_initialize();

   // Perform initialization for PSParallelCompact that requires

   // allocations.  This should be called during the VM initialization

   // at a pointer where it would be appropriate to return a JNI_ENOMEM

   // in the event of a failure.

   static bool initialize();

   // Public accessors

   static elapsedTimer* accumulated_time() { return &_accumulated_time; }

   static unsigned int total_invocations() { return _total_invocations; }

   static CollectorCounters* counters()    { return _counters; }

   // Used to add tasks

   static GCTaskManager* const gc_task_manager();

   static klassOop updated_int_array_klass_obj() {

     return _updated_int_array_klass_obj;

   }

   // Marking support

   static inline bool mark_obj(oop obj);

   static bool mark_obj(oop* p)  {

     if (*p != NULL) {

       return mark_obj(*p);

     } else {

       return false;

     }

   }

   static void mark_and_push(ParCompactionManager* cm, oop* p) {

                                           // Check mark and maybe push on

                                           // marking stack

     oop m = *p;

     if (m != NULL && mark_bitmap()->is_unmarked(m)) {

       mark_and_push_internal(cm, p);

     }

   }

   // Compaction support.

   // Return true if p is in the range [beg_addr, end_addr).

   static inline bool is_in(HeapWord* p, HeapWord* beg_addr, HeapWord* end_addr);

   static inline bool is_in(oop* p, HeapWord* beg_addr, HeapWord* end_addr);

   // Convenience wrappers for per-space data kept in _space_info.

   static inline MutableSpace*     space(SpaceId space_id);

   static inline HeapWord*         new_top(SpaceId space_id);

   static inline HeapWord*         dense_prefix(SpaceId space_id);

   static inline ObjectStartArray* start_array(SpaceId space_id);

   // Return true if the klass should be updated.

   static inline bool should_update_klass(klassOop k);

   // Move and update the live objects in the specified space.

   static void move_and_update(ParCompactionManager* cm, SpaceId space_id);

   // Process the end of the given chunk range in the dense prefix.

   // This includes saving any object not updated.

   static void dense_prefix_chunks_epilogue(ParCompactionManager* cm,

                                            size_t chunk_start_index,

                                            size_t chunk_end_index,

                                            idx_t exiting_object_offset,

                                            idx_t chunk_offset_start,

                                            idx_t chunk_offset_end);

   // Update a chunk in the dense prefix.  For each live object

   // in the chunk, update it's interior references.  For each

   // dead object, fill it with deadwood. Dead space at the end

   // of a chunk range will be filled to the start of the next

   // live object regardless of the chunk_index_end.  None of the

   // objects in the dense prefix move and dead space is dead

   // (holds only dead objects that don't need any processing), so

   // dead space can be filled in any order.

   static void update_and_deadwood_in_dense_prefix(ParCompactionManager* cm,

                                                   SpaceId space_id,

                                                   size_t chunk_index_start,

                                                   size_t chunk_index_end);

   // Return the address of the count + 1st live word in the range [beg, end).

   static HeapWord* skip_live_words(HeapWord* beg, HeapWord* end, size_t count);

   // Return the address of the word to be copied to dest_addr, which must be

   // aligned to a chunk boundary.

   static HeapWord* first_src_addr(HeapWord* const dest_addr,

                                   size_t src_chunk_idx);

   // Determine the next source chunk, set closure.source() to the start of the

   // new chunk return the chunk index.  Parameter end_addr is the address one

   // beyond the end of source range just processed.  If necessary, switch to a

   // new source space and set src_space_id (in-out parameter) and src_space_top

   // (out parameter) accordingly.

   static size_t next_src_chunk(MoveAndUpdateClosure& closure,

                                SpaceId& src_space_id,

                                HeapWord*& src_space_top,

                                HeapWord* end_addr);

   // Decrement the destination count for each non-empty source chunk in the

   // range [beg_chunk, chunk(chunk_align_up(end_addr))).

   static void decrement_destination_counts(ParCompactionManager* cm,

                                            size_t beg_chunk,

                                            HeapWord* end_addr);

   // Fill a chunk, copying objects from one or more source chunks.

   static void fill_chunk(ParCompactionManager* cm, size_t chunk_idx);

   static void fill_and_update_chunk(ParCompactionManager* cm, size_t chunk) {

     fill_chunk(cm, chunk);

   }

   // Update the deferred objects in the space.

   static void update_deferred_objects(ParCompactionManager* cm, SpaceId id);

   // Mark pointer and follow contents.

   static void mark_and_follow(ParCompactionManager* cm, oop* p);

   static ParMarkBitMap* mark_bitmap() { return &_mark_bitmap; }

   static ParallelCompactData& summary_data() { return _summary_data; }

   static inline void adjust_pointer(oop* p) { adjust_pointer(p, false); }

   static inline void adjust_pointer(oop* p,

                                     HeapWord* beg_addr,

                                     HeapWord* end_addr);

   // Reference Processing

   static ReferenceProcessor* const ref_processor() { return _ref_processor; }

   // Return the SpaceId for the given address.

   static SpaceId space_id(HeapWord* addr);

   // Time since last full gc (in milliseconds).

   static jlong millis_since_last_gc();

 #ifdef VALIDATE_MARK_SWEEP

   static void track_adjusted_pointer(oop* p, oop newobj, bool isroot);

   static void check_adjust_pointer(oop* p);     // Adjust this pointer

   static void track_interior_pointers(oop obj);

   static void check_interior_pointers();

   static void reset_live_oop_tracking(bool at_perm);

   static void register_live_oop(oop p, size_t size);

   static void validate_live_oop(oop p, size_t size);

   static void live_oop_moved_to(HeapWord* q, size_t size, HeapWord* compaction_top);

   static void compaction_complete();

   // Querying operation of RecordMarkSweepCompaction results.

   // Finds and prints the current base oop and offset for a word

   // within an oop that was live during the last GC. Helpful for

   // tracking down heap stomps.

   static void print_new_location_of_heap_address(HeapWord* q);

 #endif  // #ifdef VALIDATE_MARK_SWEEP

   // Call backs for class unloading

   // Update subklass/sibling/implementor links at end of marking.

   static void revisit_weak_klass_link(ParCompactionManager* cm, Klass* k);

 #ifndef PRODUCT

   // Debugging support.

   static const char* space_names[last_space_id];

   static void print_chunk_ranges();

   static void print_dense_prefix_stats(const char* const algorithm,

                                        const SpaceId id,

                                        const bool maximum_compaction,

                                        HeapWord* const addr);

 #endif  // #ifndef PRODUCT

 #ifdef  ASSERT

   // Verify that all the chunks have been emptied.

   static void verify_complete(SpaceId space_id);

 #endif  // #ifdef ASSERT

 };

 bool PSParallelCompact::mark_obj(oop obj) {

   const int obj_size = obj->size();

   if (mark_bitmap()->mark_obj(obj, obj_size)) {

     _summary_data.add_obj(obj, obj_size);

     return true;

   } else {

     return false;

   }

 }

 inline bool PSParallelCompact::print_phases()

 {

   return _print_phases;

 }

 inline double PSParallelCompact::normal_distribution(double density)

 {

   assert(_dwl_initialized, "uninitialized");

   const double squared_term = (density - _dwl_mean) / _dwl_std_dev;

   return _dwl_first_term * exp(-0.5 * squared_term * squared_term);

 }

 inline bool

 PSParallelCompact::dead_space_crosses_boundary(const ChunkData* chunk,

                                                idx_t bit)

 {

   assert(bit > 0, "cannot call this for the first bit/chunk");

   assert(_summary_data.chunk_to_addr(chunk) == _mark_bitmap.bit_to_addr(bit),

          "sanity check");

   // Dead space crosses the boundary if (1) a partial object does not extend

   // onto the chunk, (2) an object does not start at the beginning of the chunk,

   // and (3) an object does not end at the end of the prior chunk.

   return chunk->partial_obj_size() == 0 &&

     !_mark_bitmap.is_obj_beg(bit) &&

     !_mark_bitmap.is_obj_end(bit - 1);

 }

 inline bool

 PSParallelCompact::is_in(HeapWord* p, HeapWord* beg_addr, HeapWord* end_addr) {

   return p >= beg_addr && p < end_addr;

 }

 inline bool

 PSParallelCompact::is_in(oop* p, HeapWord* beg_addr, HeapWord* end_addr) {

   return is_in((HeapWord*)p, beg_addr, end_addr);

 }

 inline MutableSpace* PSParallelCompact::space(SpaceId id) {

   assert(id < last_space_id, "id out of range");

   return _space_info[id].space();

 }

 inline HeapWord* PSParallelCompact::new_top(SpaceId id) {

   assert(id < last_space_id, "id out of range");

   return _space_info[id].new_top();

 }

 inline HeapWord* PSParallelCompact::dense_prefix(SpaceId id) {

   assert(id < last_space_id, "id out of range");

   return _space_info[id].dense_prefix();

 }

 inline ObjectStartArray* PSParallelCompact::start_array(SpaceId id) {

   assert(id < last_space_id, "id out of range");

   return _space_info[id].start_array();

 }

 inline bool PSParallelCompact::should_update_klass(klassOop k) {

   return ((HeapWord*) k) >= dense_prefix(perm_space_id);

 }

 inline void PSParallelCompact::adjust_pointer(oop* p,

                                               HeapWord* beg_addr,

                                               HeapWord* end_addr) {

   if (is_in(p, beg_addr, end_addr)) {

     adjust_pointer(p);

   }

 }

 class MoveAndUpdateClosure: public ParMarkBitMapClosure {

  public:

   inline MoveAndUpdateClosure(ParMarkBitMap* bitmap, ParCompactionManager* cm,

                               ObjectStartArray* start_array,

                               HeapWord* destination, size_t words);

   // Accessors.

   HeapWord* destination() const         { return _destination; }

   // If the object will fit (size <= words_remaining()), copy it to the current

   // destination, update the interior oops and the start array and return either

   // full (if the closure is full) or incomplete.  If the object will not fit,

   // return would_overflow.

   virtual IterationStatus do_addr(HeapWord* addr, size_t size);

   // Copy enough words to fill this closure, starting at source().  Interior

   // oops and the start array are not updated.  Return full.

   IterationStatus copy_until_full();

   // Copy enough words to fill this closure or to the end of an object,

   // whichever is smaller, starting at source().  Interior oops and the start

   // array are not updated.

   void copy_partial_obj();

  protected:

   // Update variables to indicate that word_count words were processed.

   inline void update_state(size_t word_count);

  protected:

   ObjectStartArray* const _start_array;

   HeapWord*               _destination;         // Next addr to be written.

 };

 inline

 MoveAndUpdateClosure::MoveAndUpdateClosure(ParMarkBitMap* bitmap,

                                            ParCompactionManager* cm,

                                            ObjectStartArray* start_array,

                                            HeapWord* destination,

                                            size_t words) :

   ParMarkBitMapClosure(bitmap, cm, words), _start_array(start_array)

 {

   _destination = destination;

 }

 inline void MoveAndUpdateClosure::update_state(size_t words)

 {

   decrement_words_remaining(words);

   _source += words;

   _destination += words;

 }

 class UpdateOnlyClosure: public ParMarkBitMapClosure {

  private:

   const PSParallelCompact::SpaceId _space_id;

   ObjectStartArray* const          _start_array;

  public:

   UpdateOnlyClosure(ParMarkBitMap* mbm,

                     ParCompactionManager* cm,

                     PSParallelCompact::SpaceId space_id);

   // Update the object.

   virtual IterationStatus do_addr(HeapWord* addr, size_t words);

   inline void do_addr(HeapWord* addr);

 };

 inline void UpdateOnlyClosure::do_addr(HeapWord* addr) {

   _start_array->allocate_block(addr);

   oop(addr)->update_contents(compaction_manager());

 }

 class FillClosure: public ParMarkBitMapClosure {

 public:

   FillClosure(ParCompactionManager* cm, PSParallelCompact::SpaceId space_id):

     ParMarkBitMapClosure(PSParallelCompact::mark_bitmap(), cm),

     _space_id(space_id),

     _start_array(PSParallelCompact::start_array(space_id))

   {

     assert(_space_id == PSParallelCompact::perm_space_id ||

            _space_id == PSParallelCompact::old_space_id,

            "cannot use FillClosure in the young gen");

     assert(bitmap() != NULL, "need a bitmap");

     assert(_start_array != NULL, "need a start array");

   }

   void fill_region(HeapWord* addr, size_t size) {

     MemRegion region(addr, size);

     SharedHeap::fill_region_with_object(region);

     _start_array->allocate_block(addr);

   }

   virtual IterationStatus do_addr(HeapWord* addr, size_t size) {

     fill_region(addr, size);

     return ParMarkBitMap::incomplete;

   }

 private:

   const PSParallelCompact::SpaceId _space_id;

   ObjectStartArray* const          _start_array;

 };