1 /*
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   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
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   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
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  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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  20  * or visit www.oracle.com if you need additional information or have any
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  24 
  25 #ifndef SHARE_GC_PARALLEL_PSPARALLELCOMPACT_HPP
  26 #define SHARE_GC_PARALLEL_PSPARALLELCOMPACT_HPP
  27 
  28 #include "gc/parallel/mutableSpace.hpp"
  29 #include "gc/parallel/objectStartArray.hpp"
  30 #include "gc/parallel/parMarkBitMap.hpp"
  31 #include "gc/parallel/parallelScavengeHeap.hpp"
  32 #include "gc/shared/collectedHeap.hpp"
  33 #include "gc/shared/collectorCounters.hpp"
  34 #include "oops/oop.hpp"
  35 
  36 class ParallelScavengeHeap;
  37 class PSAdaptiveSizePolicy;
  38 class PSYoungGen;
  39 class PSOldGen;
  40 class ParCompactionManager;
  41 class ParallelTaskTerminator;
  42 class PSParallelCompact;
  43 class PreGCValues;
  44 class MoveAndUpdateClosure;
  45 class RefProcTaskExecutor;
  46 class ParallelOldTracer;
  47 class STWGCTimer;
  48 
  49 // The SplitInfo class holds the information needed to 'split' a source region
  50 // so that the live data can be copied to two destination *spaces*.  Normally,
  51 // all the live data in a region is copied to a single destination space (e.g.,
  52 // everything live in a region in eden is copied entirely into the old gen).
  53 // However, when the heap is nearly full, all the live data in eden may not fit
  54 // into the old gen.  Copying only some of the regions from eden to old gen
  55 // requires finding a region that does not contain a partial object (i.e., no
  56 // live object crosses the region boundary) somewhere near the last object that
  57 // does fit into the old gen.  Since it's not always possible to find such a
  58 // region, splitting is necessary for predictable behavior.
  59 //
  60 // A region is always split at the end of the partial object.  This avoids
  61 // additional tests when calculating the new location of a pointer, which is a
  62 // very hot code path.  The partial object and everything to its left will be
  63 // copied to another space (call it dest_space_1).  The live data to the right
  64 // of the partial object will be copied either within the space itself, or to a
  65 // different destination space (distinct from dest_space_1).
  66 //
  67 // Split points are identified during the summary phase, when region
  68 // destinations are computed:  data about the split, including the
  69 // partial_object_size, is recorded in a SplitInfo record and the
  70 // partial_object_size field in the summary data is set to zero.  The zeroing is
  71 // possible (and necessary) since the partial object will move to a different
  72 // destination space than anything to its right, thus the partial object should
  73 // not affect the locations of any objects to its right.
  74 //
  75 // The recorded data is used during the compaction phase, but only rarely:  when
  76 // the partial object on the split region will be copied across a destination
  77 // region boundary.  This test is made once each time a region is filled, and is
  78 // a simple address comparison, so the overhead is negligible (see
  79 // PSParallelCompact::first_src_addr()).
  80 //
  81 // Notes:
  82 //
  83 // Only regions with partial objects are split; a region without a partial
  84 // object does not need any extra bookkeeping.
  85 //
  86 // At most one region is split per space, so the amount of data required is
  87 // constant.
  88 //
  89 // A region is split only when the destination space would overflow.  Once that
  90 // happens, the destination space is abandoned and no other data (even from
  91 // other source spaces) is targeted to that destination space.  Abandoning the
  92 // destination space may leave a somewhat large unused area at the end, if a
  93 // large object caused the overflow.
  94 //
  95 // Future work:
  96 //
  97 // More bookkeeping would be required to continue to use the destination space.
  98 // The most general solution would allow data from regions in two different
  99 // source spaces to be "joined" in a single destination region.  At the very
 100 // least, additional code would be required in next_src_region() to detect the
 101 // join and skip to an out-of-order source region.  If the join region was also
 102 // the last destination region to which a split region was copied (the most
 103 // likely case), then additional work would be needed to get fill_region() to
 104 // stop iteration and switch to a new source region at the right point.  Basic
 105 // idea would be to use a fake value for the top of the source space.  It is
 106 // doable, if a bit tricky.
 107 //
 108 // A simpler (but less general) solution would fill the remainder of the
 109 // destination region with a dummy object and continue filling the next
 110 // destination region.
 111 
 112 class SplitInfo
 113 {
 114 public:
 115   // Return true if this split info is valid (i.e., if a split has been
 116   // recorded).  The very first region cannot have a partial object and thus is
 117   // never split, so 0 is the 'invalid' value.
 118   bool is_valid() const { return _src_region_idx > 0; }
 119 
 120   // Return true if this split holds data for the specified source region.
 121   inline bool is_split(size_t source_region) const;
 122 
 123   // The index of the split region, the size of the partial object on that
 124   // region and the destination of the partial object.
 125   size_t    src_region_idx() const   { return _src_region_idx; }
 126   size_t    partial_obj_size() const { return _partial_obj_size; }
 127   HeapWord* destination() const      { return _destination; }
 128 
 129   // The destination count of the partial object referenced by this split
 130   // (either 1 or 2).  This must be added to the destination count of the
 131   // remainder of the source region.
 132   unsigned int destination_count() const { return _destination_count; }
 133 
 134   // If a word within the partial object will be written to the first word of a
 135   // destination region, this is the address of the destination region;
 136   // otherwise this is NULL.
 137   HeapWord* dest_region_addr() const     { return _dest_region_addr; }
 138 
 139   // If a word within the partial object will be written to the first word of a
 140   // destination region, this is the address of that word within the partial
 141   // object; otherwise this is NULL.
 142   HeapWord* first_src_addr() const       { return _first_src_addr; }
 143 
 144   // Record the data necessary to split the region src_region_idx.
 145   void record(size_t src_region_idx, size_t partial_obj_size,
 146               HeapWord* destination);
 147 
 148   void clear();
 149 
 150   DEBUG_ONLY(void verify_clear();)
 151 
 152 private:
 153   size_t       _src_region_idx;
 154   size_t       _partial_obj_size;
 155   HeapWord*    _destination;
 156   unsigned int _destination_count;
 157   HeapWord*    _dest_region_addr;
 158   HeapWord*    _first_src_addr;
 159 };
 160 
 161 inline bool SplitInfo::is_split(size_t region_idx) const
 162 {
 163   return _src_region_idx == region_idx && is_valid();
 164 }
 165 
 166 class SpaceInfo
 167 {
 168  public:
 169   MutableSpace* space() const { return _space; }
 170 
 171   // Where the free space will start after the collection.  Valid only after the
 172   // summary phase completes.
 173   HeapWord* new_top() const { return _new_top; }
 174 
 175   // Allows new_top to be set.
 176   HeapWord** new_top_addr() { return &_new_top; }
 177 
 178   // Where the smallest allowable dense prefix ends (used only for perm gen).
 179   HeapWord* min_dense_prefix() const { return _min_dense_prefix; }
 180 
 181   // Where the dense prefix ends, or the compacted region begins.
 182   HeapWord* dense_prefix() const { return _dense_prefix; }
 183 
 184   // The start array for the (generation containing the) space, or NULL if there
 185   // is no start array.
 186   ObjectStartArray* start_array() const { return _start_array; }
 187 
 188   SplitInfo& split_info() { return _split_info; }
 189 
 190   void set_space(MutableSpace* s)           { _space = s; }
 191   void set_new_top(HeapWord* addr)          { _new_top = addr; }
 192   void set_min_dense_prefix(HeapWord* addr) { _min_dense_prefix = addr; }
 193   void set_dense_prefix(HeapWord* addr)     { _dense_prefix = addr; }
 194   void set_start_array(ObjectStartArray* s) { _start_array = s; }
 195 
 196   void publish_new_top() const              { _space->set_top(_new_top); }
 197 
 198  private:
 199   MutableSpace*     _space;
 200   HeapWord*         _new_top;
 201   HeapWord*         _min_dense_prefix;
 202   HeapWord*         _dense_prefix;
 203   ObjectStartArray* _start_array;
 204   SplitInfo         _split_info;
 205 };
 206 
 207 class ParallelCompactData
 208 {
 209 public:
 210   // Sizes are in HeapWords, unless indicated otherwise.
 211   static const size_t Log2RegionSize;
 212   static const size_t RegionSize;
 213   static const size_t RegionSizeBytes;
 214 
 215   // Mask for the bits in a size_t to get an offset within a region.
 216   static const size_t RegionSizeOffsetMask;
 217   // Mask for the bits in a pointer to get an offset within a region.
 218   static const size_t RegionAddrOffsetMask;
 219   // Mask for the bits in a pointer to get the address of the start of a region.
 220   static const size_t RegionAddrMask;
 221 
 222   static const size_t Log2BlockSize;
 223   static const size_t BlockSize;
 224   static const size_t BlockSizeBytes;
 225 
 226   static const size_t BlockSizeOffsetMask;
 227   static const size_t BlockAddrOffsetMask;
 228   static const size_t BlockAddrMask;
 229 
 230   static const size_t BlocksPerRegion;
 231   static const size_t Log2BlocksPerRegion;
 232 
 233   class RegionData
 234   {
 235   public:
 236     // Destination address of the region.
 237     HeapWord* destination() const { return _destination; }
 238 
 239     // The first region containing data destined for this region.
 240     size_t source_region() const { return _source_region; }
 241 
 242     // The object (if any) starting in this region and ending in a different
 243     // region that could not be updated during the main (parallel) compaction
 244     // phase.  This is different from _partial_obj_addr, which is an object that
 245     // extends onto a source region.  However, the two uses do not overlap in
 246     // time, so the same field is used to save space.
 247     HeapWord* deferred_obj_addr() const { return _partial_obj_addr; }
 248 
 249     // The starting address of the partial object extending onto the region.
 250     HeapWord* partial_obj_addr() const { return _partial_obj_addr; }
 251 
 252     // Size of the partial object extending onto the region (words).
 253     size_t partial_obj_size() const { return _partial_obj_size; }
 254 
 255     // Size of live data that lies within this region due to objects that start
 256     // in this region (words).  This does not include the partial object
 257     // extending onto the region (if any), or the part of an object that extends
 258     // onto the next region (if any).
 259     size_t live_obj_size() const { return _dc_and_los & los_mask; }
 260 
 261     // Total live data that lies within the region (words).
 262     size_t data_size() const { return partial_obj_size() + live_obj_size(); }
 263 
 264     // The destination_count is the number of other regions to which data from
 265     // this region will be copied.  At the end of the summary phase, the valid
 266     // values of destination_count are
 267     //
 268     // 0 - data from the region will be compacted completely into itself, or the
 269     //     region is empty.  The region can be claimed and then filled.
 270     // 1 - data from the region will be compacted into 1 other region; some
 271     //     data from the region may also be compacted into the region itself.
 272     // 2 - data from the region will be copied to 2 other regions.
 273     //
 274     // During compaction as regions are emptied, the destination_count is
 275     // decremented (atomically) and when it reaches 0, it can be claimed and
 276     // then filled.
 277     //
 278     // A region is claimed for processing by atomically changing the
 279     // destination_count to the claimed value (dc_claimed).  After a region has
 280     // been filled, the destination_count should be set to the completed value
 281     // (dc_completed).
 282     inline uint destination_count() const;
 283     inline uint destination_count_raw() const;
 284 
 285     // Whether the block table for this region has been filled.
 286     inline bool blocks_filled() const;
 287 
 288     // Number of times the block table was filled.
 289     DEBUG_ONLY(inline size_t blocks_filled_count() const;)
 290 
 291     // The location of the java heap data that corresponds to this region.
 292     inline HeapWord* data_location() const;
 293 
 294     // The highest address referenced by objects in this region.
 295     inline HeapWord* highest_ref() const;
 296 
 297     // Whether this region is available to be claimed, has been claimed, or has
 298     // been completed.
 299     //
 300     // Minor subtlety:  claimed() returns true if the region is marked
 301     // completed(), which is desirable since a region must be claimed before it
 302     // can be completed.
 303     bool available() const { return _dc_and_los < dc_one; }
 304     bool claimed()   const { return _dc_and_los >= dc_claimed; }
 305     bool completed() const { return _dc_and_los >= dc_completed; }
 306 
 307     // These are not atomic.
 308     void set_destination(HeapWord* addr)       { _destination = addr; }
 309     void set_source_region(size_t region)      { _source_region = region; }
 310     void set_deferred_obj_addr(HeapWord* addr) { _partial_obj_addr = addr; }
 311     void set_partial_obj_addr(HeapWord* addr)  { _partial_obj_addr = addr; }
 312     void set_partial_obj_size(size_t words)    {
 313       _partial_obj_size = (region_sz_t) words;
 314     }
 315     inline void set_blocks_filled();
 316 
 317     inline void set_destination_count(uint count);
 318     inline void set_live_obj_size(size_t words);
 319     inline void set_data_location(HeapWord* addr);
 320     inline void set_completed();
 321     inline bool claim_unsafe();
 322 
 323     // These are atomic.
 324     inline void add_live_obj(size_t words);
 325     inline void set_highest_ref(HeapWord* addr);
 326     inline void decrement_destination_count();
 327     inline bool claim();
 328 
 329   private:
 330     // The type used to represent object sizes within a region.
 331     typedef uint region_sz_t;
 332 
 333     // Constants for manipulating the _dc_and_los field, which holds both the
 334     // destination count and live obj size.  The live obj size lives at the
 335     // least significant end so no masking is necessary when adding.
 336     static const region_sz_t dc_shift;           // Shift amount.
 337     static const region_sz_t dc_mask;            // Mask for destination count.
 338     static const region_sz_t dc_one;             // 1, shifted appropriately.
 339     static const region_sz_t dc_claimed;         // Region has been claimed.
 340     static const region_sz_t dc_completed;       // Region has been completed.
 341     static const region_sz_t los_mask;           // Mask for live obj size.
 342 
 343     HeapWord*            _destination;
 344     size_t               _source_region;
 345     HeapWord*            _partial_obj_addr;
 346     region_sz_t          _partial_obj_size;
 347     region_sz_t volatile _dc_and_los;
 348     bool        volatile _blocks_filled;
 349 
 350 #ifdef ASSERT
 351     size_t               _blocks_filled_count;   // Number of block table fills.
 352 
 353     // These enable optimizations that are only partially implemented.  Use
 354     // debug builds to prevent the code fragments from breaking.
 355     HeapWord*            _data_location;
 356     HeapWord*            _highest_ref;
 357 #endif  // #ifdef ASSERT
 358 
 359 #ifdef ASSERT
 360    public:
 361     uint                 _pushed;   // 0 until region is pushed onto a stack
 362    private:
 363 #endif
 364   };
 365 
 366   // "Blocks" allow shorter sections of the bitmap to be searched.  Each Block
 367   // holds an offset, which is the amount of live data in the Region to the left
 368   // of the first live object that starts in the Block.
 369   class BlockData
 370   {
 371   public:
 372     typedef unsigned short int blk_ofs_t;
 373 
 374     blk_ofs_t offset() const    { return _offset; }
 375     void set_offset(size_t val) { _offset = (blk_ofs_t)val; }
 376 
 377   private:
 378     blk_ofs_t _offset;
 379   };
 380 
 381 public:
 382   ParallelCompactData();
 383   bool initialize(MemRegion covered_region);
 384 
 385   size_t region_count() const { return _region_count; }
 386   size_t reserved_byte_size() const { return _reserved_byte_size; }
 387 
 388   // Convert region indices to/from RegionData pointers.
 389   inline RegionData* region(size_t region_idx) const;
 390   inline size_t     region(const RegionData* const region_ptr) const;
 391 
 392   size_t block_count() const { return _block_count; }
 393   inline BlockData* block(size_t block_idx) const;
 394   inline size_t     block(const BlockData* block_ptr) const;
 395 
 396   void add_obj(HeapWord* addr, size_t len);
 397   void add_obj(oop p, size_t len) { add_obj((HeapWord*)p, len); }
 398 
 399   // Fill in the regions covering [beg, end) so that no data moves; i.e., the
 400   // destination of region n is simply the start of region n.  The argument beg
 401   // must be region-aligned; end need not be.
 402   void summarize_dense_prefix(HeapWord* beg, HeapWord* end);
 403 
 404   HeapWord* summarize_split_space(size_t src_region, SplitInfo& split_info,
 405                                   HeapWord* destination, HeapWord* target_end,
 406                                   HeapWord** target_next);
 407   bool summarize(SplitInfo& split_info,
 408                  HeapWord* source_beg, HeapWord* source_end,
 409                  HeapWord** source_next,
 410                  HeapWord* target_beg, HeapWord* target_end,
 411                  HeapWord** target_next);
 412 
 413   void clear();
 414   void clear_range(size_t beg_region, size_t end_region);
 415   void clear_range(HeapWord* beg, HeapWord* end) {
 416     clear_range(addr_to_region_idx(beg), addr_to_region_idx(end));
 417   }
 418 
 419   // Return the number of words between addr and the start of the region
 420   // containing addr.
 421   inline size_t     region_offset(const HeapWord* addr) const;
 422 
 423   // Convert addresses to/from a region index or region pointer.
 424   inline size_t     addr_to_region_idx(const HeapWord* addr) const;
 425   inline RegionData* addr_to_region_ptr(const HeapWord* addr) const;
 426   inline HeapWord*  region_to_addr(size_t region) const;
 427   inline HeapWord*  region_to_addr(size_t region, size_t offset) const;
 428   inline HeapWord*  region_to_addr(const RegionData* region) const;
 429 
 430   inline HeapWord*  region_align_down(HeapWord* addr) const;
 431   inline HeapWord*  region_align_up(HeapWord* addr) const;
 432   inline bool       is_region_aligned(HeapWord* addr) const;
 433 
 434   // Analogous to region_offset() for blocks.
 435   size_t     block_offset(const HeapWord* addr) const;
 436   size_t     addr_to_block_idx(const HeapWord* addr) const;
 437   size_t     addr_to_block_idx(const oop obj) const {
 438     return addr_to_block_idx((HeapWord*) obj);
 439   }
 440   inline BlockData* addr_to_block_ptr(const HeapWord* addr) const;
 441   inline HeapWord*  block_to_addr(size_t block) const;
 442   inline size_t     region_to_block_idx(size_t region) const;
 443 
 444   inline HeapWord*  block_align_down(HeapWord* addr) const;
 445   inline HeapWord*  block_align_up(HeapWord* addr) const;
 446   inline bool       is_block_aligned(HeapWord* addr) const;
 447 
 448   // Return the address one past the end of the partial object.
 449   HeapWord* partial_obj_end(size_t region_idx) const;
 450 
 451   // Return the location of the object after compaction.
 452   HeapWord* calc_new_pointer(HeapWord* addr, ParCompactionManager* cm);
 453 
 454   HeapWord* calc_new_pointer(oop p, ParCompactionManager* cm) {
 455     return calc_new_pointer((HeapWord*) p, cm);
 456   }
 457 
 458 #ifdef  ASSERT
 459   void verify_clear(const PSVirtualSpace* vspace);
 460   void verify_clear();
 461 #endif  // #ifdef ASSERT
 462 
 463 private:
 464   bool initialize_block_data();
 465   bool initialize_region_data(size_t region_size);
 466   PSVirtualSpace* create_vspace(size_t count, size_t element_size);
 467 
 468 private:
 469   HeapWord*       _region_start;
 470 #ifdef  ASSERT
 471   HeapWord*       _region_end;
 472 #endif  // #ifdef ASSERT
 473 
 474   PSVirtualSpace* _region_vspace;
 475   size_t          _reserved_byte_size;
 476   RegionData*     _region_data;
 477   size_t          _region_count;
 478 
 479   PSVirtualSpace* _block_vspace;
 480   BlockData*      _block_data;
 481   size_t          _block_count;
 482 };
 483 
 484 inline uint
 485 ParallelCompactData::RegionData::destination_count_raw() const
 486 {
 487   return _dc_and_los & dc_mask;
 488 }
 489 
 490 inline uint
 491 ParallelCompactData::RegionData::destination_count() const
 492 {
 493   return destination_count_raw() >> dc_shift;
 494 }
 495 
 496 inline bool
 497 ParallelCompactData::RegionData::blocks_filled() const
 498 {
 499   bool result = _blocks_filled;
 500   OrderAccess::acquire();
 501   return result;
 502 }
 503 
 504 #ifdef ASSERT
 505 inline size_t
 506 ParallelCompactData::RegionData::blocks_filled_count() const
 507 {
 508   return _blocks_filled_count;
 509 }
 510 #endif // #ifdef ASSERT
 511 
 512 inline void
 513 ParallelCompactData::RegionData::set_blocks_filled()
 514 {
 515   OrderAccess::release();
 516   _blocks_filled = true;
 517   // Debug builds count the number of times the table was filled.
 518   DEBUG_ONLY(Atomic::inc(&_blocks_filled_count));
 519 }
 520 
 521 inline void
 522 ParallelCompactData::RegionData::set_destination_count(uint count)
 523 {
 524   assert(count <= (dc_completed >> dc_shift), "count too large");
 525   const region_sz_t live_sz = (region_sz_t) live_obj_size();
 526   _dc_and_los = (count << dc_shift) | live_sz;
 527 }
 528 
 529 inline void ParallelCompactData::RegionData::set_live_obj_size(size_t words)
 530 {
 531   assert(words <= los_mask, "would overflow");
 532   _dc_and_los = destination_count_raw() | (region_sz_t)words;
 533 }
 534 
 535 inline void ParallelCompactData::RegionData::decrement_destination_count()
 536 {
 537   assert(_dc_and_los < dc_claimed, "already claimed");
 538   assert(_dc_and_los >= dc_one, "count would go negative");
 539   Atomic::add(dc_mask, &_dc_and_los);
 540 }
 541 
 542 inline HeapWord* ParallelCompactData::RegionData::data_location() const
 543 {
 544   DEBUG_ONLY(return _data_location;)
 545   NOT_DEBUG(return NULL;)
 546 }
 547 
 548 inline HeapWord* ParallelCompactData::RegionData::highest_ref() const
 549 {
 550   DEBUG_ONLY(return _highest_ref;)
 551   NOT_DEBUG(return NULL;)
 552 }
 553 
 554 inline void ParallelCompactData::RegionData::set_data_location(HeapWord* addr)
 555 {
 556   DEBUG_ONLY(_data_location = addr;)
 557 }
 558 
 559 inline void ParallelCompactData::RegionData::set_completed()
 560 {
 561   assert(claimed(), "must be claimed first");
 562   _dc_and_los = dc_completed | (region_sz_t) live_obj_size();
 563 }
 564 
 565 // MT-unsafe claiming of a region.  Should only be used during single threaded
 566 // execution.
 567 inline bool ParallelCompactData::RegionData::claim_unsafe()
 568 {
 569   if (available()) {
 570     _dc_and_los |= dc_claimed;
 571     return true;
 572   }
 573   return false;
 574 }
 575 
 576 inline void ParallelCompactData::RegionData::add_live_obj(size_t words)
 577 {
 578   assert(words <= (size_t)los_mask - live_obj_size(), "overflow");
 579   Atomic::add(static_cast<region_sz_t>(words), &_dc_and_los);
 580 }
 581 
 582 inline void ParallelCompactData::RegionData::set_highest_ref(HeapWord* addr)
 583 {
 584 #ifdef ASSERT
 585   HeapWord* tmp = _highest_ref;
 586   while (addr > tmp) {
 587     tmp = Atomic::cmpxchg(addr, &_highest_ref, tmp);
 588   }
 589 #endif  // #ifdef ASSERT
 590 }
 591 
 592 inline bool ParallelCompactData::RegionData::claim()
 593 {
 594   const region_sz_t los = static_cast<region_sz_t>(live_obj_size());
 595   const region_sz_t old = Atomic::cmpxchg(dc_claimed | los, &_dc_and_los, los);
 596   return old == los;
 597 }
 598 
 599 inline ParallelCompactData::RegionData*
 600 ParallelCompactData::region(size_t region_idx) const
 601 {
 602   assert(region_idx <= region_count(), "bad arg");
 603   return _region_data + region_idx;
 604 }
 605 
 606 inline size_t
 607 ParallelCompactData::region(const RegionData* const region_ptr) const
 608 {
 609   assert(region_ptr >= _region_data, "bad arg");
 610   assert(region_ptr <= _region_data + region_count(), "bad arg");
 611   return pointer_delta(region_ptr, _region_data, sizeof(RegionData));
 612 }
 613 
 614 inline ParallelCompactData::BlockData*
 615 ParallelCompactData::block(size_t n) const {
 616   assert(n < block_count(), "bad arg");
 617   return _block_data + n;
 618 }
 619 
 620 inline size_t
 621 ParallelCompactData::region_offset(const HeapWord* addr) const
 622 {
 623   assert(addr >= _region_start, "bad addr");
 624   assert(addr <= _region_end, "bad addr");
 625   return (size_t(addr) & RegionAddrOffsetMask) >> LogHeapWordSize;
 626 }
 627 
 628 inline size_t
 629 ParallelCompactData::addr_to_region_idx(const HeapWord* addr) const
 630 {
 631   assert(addr >= _region_start, "bad addr " PTR_FORMAT " _region_start " PTR_FORMAT, p2i(addr), p2i(_region_start));
 632   assert(addr <= _region_end, "bad addr " PTR_FORMAT " _region_end " PTR_FORMAT, p2i(addr), p2i(_region_end));
 633   return pointer_delta(addr, _region_start) >> Log2RegionSize;
 634 }
 635 
 636 inline ParallelCompactData::RegionData*
 637 ParallelCompactData::addr_to_region_ptr(const HeapWord* addr) const
 638 {
 639   return region(addr_to_region_idx(addr));
 640 }
 641 
 642 inline HeapWord*
 643 ParallelCompactData::region_to_addr(size_t region) const
 644 {
 645   assert(region <= _region_count, "region out of range");
 646   return _region_start + (region << Log2RegionSize);
 647 }
 648 
 649 inline HeapWord*
 650 ParallelCompactData::region_to_addr(const RegionData* region) const
 651 {
 652   return region_to_addr(pointer_delta(region, _region_data,
 653                                       sizeof(RegionData)));
 654 }
 655 
 656 inline HeapWord*
 657 ParallelCompactData::region_to_addr(size_t region, size_t offset) const
 658 {
 659   assert(region <= _region_count, "region out of range");
 660   assert(offset < RegionSize, "offset too big");  // This may be too strict.
 661   return region_to_addr(region) + offset;
 662 }
 663 
 664 inline HeapWord*
 665 ParallelCompactData::region_align_down(HeapWord* addr) const
 666 {
 667   assert(addr >= _region_start, "bad addr");
 668   assert(addr < _region_end + RegionSize, "bad addr");
 669   return (HeapWord*)(size_t(addr) & RegionAddrMask);
 670 }
 671 
 672 inline HeapWord*
 673 ParallelCompactData::region_align_up(HeapWord* addr) const
 674 {
 675   assert(addr >= _region_start, "bad addr");
 676   assert(addr <= _region_end, "bad addr");
 677   return region_align_down(addr + RegionSizeOffsetMask);
 678 }
 679 
 680 inline bool
 681 ParallelCompactData::is_region_aligned(HeapWord* addr) const
 682 {
 683   return region_offset(addr) == 0;
 684 }
 685 
 686 inline size_t
 687 ParallelCompactData::block_offset(const HeapWord* addr) const
 688 {
 689   assert(addr >= _region_start, "bad addr");
 690   assert(addr <= _region_end, "bad addr");
 691   return (size_t(addr) & BlockAddrOffsetMask) >> LogHeapWordSize;
 692 }
 693 
 694 inline size_t
 695 ParallelCompactData::addr_to_block_idx(const HeapWord* addr) const
 696 {
 697   assert(addr >= _region_start, "bad addr");
 698   assert(addr <= _region_end, "bad addr");
 699   return pointer_delta(addr, _region_start) >> Log2BlockSize;
 700 }
 701 
 702 inline ParallelCompactData::BlockData*
 703 ParallelCompactData::addr_to_block_ptr(const HeapWord* addr) const
 704 {
 705   return block(addr_to_block_idx(addr));
 706 }
 707 
 708 inline HeapWord*
 709 ParallelCompactData::block_to_addr(size_t block) const
 710 {
 711   assert(block < _block_count, "block out of range");
 712   return _region_start + (block << Log2BlockSize);
 713 }
 714 
 715 inline size_t
 716 ParallelCompactData::region_to_block_idx(size_t region) const
 717 {
 718   return region << Log2BlocksPerRegion;
 719 }
 720 
 721 inline HeapWord*
 722 ParallelCompactData::block_align_down(HeapWord* addr) const
 723 {
 724   assert(addr >= _region_start, "bad addr");
 725   assert(addr < _region_end + RegionSize, "bad addr");
 726   return (HeapWord*)(size_t(addr) & BlockAddrMask);
 727 }
 728 
 729 inline HeapWord*
 730 ParallelCompactData::block_align_up(HeapWord* addr) const
 731 {
 732   assert(addr >= _region_start, "bad addr");
 733   assert(addr <= _region_end, "bad addr");
 734   return block_align_down(addr + BlockSizeOffsetMask);
 735 }
 736 
 737 inline bool
 738 ParallelCompactData::is_block_aligned(HeapWord* addr) const
 739 {
 740   return block_offset(addr) == 0;
 741 }
 742 
 743 // Abstract closure for use with ParMarkBitMap::iterate(), which will invoke the
 744 // do_addr() method.
 745 //
 746 // The closure is initialized with the number of heap words to process
 747 // (words_remaining()), and becomes 'full' when it reaches 0.  The do_addr()
 748 // methods in subclasses should update the total as words are processed.  Since
 749 // only one subclass actually uses this mechanism to terminate iteration, the
 750 // default initial value is > 0.  The implementation is here and not in the
 751 // single subclass that uses it to avoid making is_full() virtual, and thus
 752 // adding a virtual call per live object.
 753 
 754 class ParMarkBitMapClosure: public StackObj {
 755  public:
 756   typedef ParMarkBitMap::idx_t idx_t;
 757   typedef ParMarkBitMap::IterationStatus IterationStatus;
 758 
 759  public:
 760   inline ParMarkBitMapClosure(ParMarkBitMap* mbm, ParCompactionManager* cm,
 761                               size_t words = max_uintx);
 762 
 763   inline ParCompactionManager* compaction_manager() const;
 764   inline ParMarkBitMap*        bitmap() const;
 765   inline size_t                words_remaining() const;
 766   inline bool                  is_full() const;
 767   inline HeapWord*             source() const;
 768 
 769   inline void                  set_source(HeapWord* addr);
 770 
 771   virtual IterationStatus do_addr(HeapWord* addr, size_t words) = 0;
 772 
 773  protected:
 774   inline void decrement_words_remaining(size_t words);
 775 
 776  private:
 777   ParMarkBitMap* const        _bitmap;
 778   ParCompactionManager* const _compaction_manager;
 779   DEBUG_ONLY(const size_t     _initial_words_remaining;) // Useful in debugger.
 780   size_t                      _words_remaining; // Words left to copy.
 781 
 782  protected:
 783   HeapWord*                   _source;          // Next addr that would be read.
 784 };
 785 
 786 inline
 787 ParMarkBitMapClosure::ParMarkBitMapClosure(ParMarkBitMap* bitmap,
 788                                            ParCompactionManager* cm,
 789                                            size_t words):
 790   _bitmap(bitmap), _compaction_manager(cm)
 791 #ifdef  ASSERT
 792   , _initial_words_remaining(words)
 793 #endif
 794 {
 795   _words_remaining = words;
 796   _source = NULL;
 797 }
 798 
 799 inline ParCompactionManager* ParMarkBitMapClosure::compaction_manager() const {
 800   return _compaction_manager;
 801 }
 802 
 803 inline ParMarkBitMap* ParMarkBitMapClosure::bitmap() const {
 804   return _bitmap;
 805 }
 806 
 807 inline size_t ParMarkBitMapClosure::words_remaining() const {
 808   return _words_remaining;
 809 }
 810 
 811 inline bool ParMarkBitMapClosure::is_full() const {
 812   return words_remaining() == 0;
 813 }
 814 
 815 inline HeapWord* ParMarkBitMapClosure::source() const {
 816   return _source;
 817 }
 818 
 819 inline void ParMarkBitMapClosure::set_source(HeapWord* addr) {
 820   _source = addr;
 821 }
 822 
 823 inline void ParMarkBitMapClosure::decrement_words_remaining(size_t words) {
 824   assert(_words_remaining >= words, "processed too many words");
 825   _words_remaining -= words;
 826 }
 827 
 828 // The UseParallelOldGC collector is a stop-the-world garbage collector that
 829 // does parts of the collection using parallel threads.  The collection includes
 830 // the tenured generation and the young generation.  The permanent generation is
 831 // collected at the same time as the other two generations but the permanent
 832 // generation is collect by a single GC thread.  The permanent generation is
 833 // collected serially because of the requirement that during the processing of a
 834 // klass AAA, any objects reference by AAA must already have been processed.
 835 // This requirement is enforced by a left (lower address) to right (higher
 836 // address) sliding compaction.
 837 //
 838 // There are four phases of the collection.
 839 //
 840 //      - marking phase
 841 //      - summary phase
 842 //      - compacting phase
 843 //      - clean up phase
 844 //
 845 // Roughly speaking these phases correspond, respectively, to
 846 //      - mark all the live objects
 847 //      - calculate the destination of each object at the end of the collection
 848 //      - move the objects to their destination
 849 //      - update some references and reinitialize some variables
 850 //
 851 // These three phases are invoked in PSParallelCompact::invoke_no_policy().  The
 852 // marking phase is implemented in PSParallelCompact::marking_phase() and does a
 853 // complete marking of the heap.  The summary phase is implemented in
 854 // PSParallelCompact::summary_phase().  The move and update phase is implemented
 855 // in PSParallelCompact::compact().
 856 //
 857 // A space that is being collected is divided into regions and with each region
 858 // is associated an object of type ParallelCompactData.  Each region is of a
 859 // fixed size and typically will contain more than 1 object and may have parts
 860 // of objects at the front and back of the region.
 861 //
 862 // region            -----+---------------------+----------
 863 // objects covered   [ AAA  )[ BBB )[ CCC   )[ DDD     )
 864 //
 865 // The marking phase does a complete marking of all live objects in the heap.
 866 // The marking also compiles the size of the data for all live objects covered
 867 // by the region.  This size includes the part of any live object spanning onto
 868 // the region (part of AAA if it is live) from the front, all live objects
 869 // contained in the region (BBB and/or CCC if they are live), and the part of
 870 // any live objects covered by the region that extends off the region (part of
 871 // DDD if it is live).  The marking phase uses multiple GC threads and marking
 872 // is done in a bit array of type ParMarkBitMap.  The marking of the bit map is
 873 // done atomically as is the accumulation of the size of the live objects
 874 // covered by a region.
 875 //
 876 // The summary phase calculates the total live data to the left of each region
 877 // XXX.  Based on that total and the bottom of the space, it can calculate the
 878 // starting location of the live data in XXX.  The summary phase calculates for
 879 // each region XXX quantities such as
 880 //
 881 //      - the amount of live data at the beginning of a region from an object
 882 //        entering the region.
 883 //      - the location of the first live data on the region
 884 //      - a count of the number of regions receiving live data from XXX.
 885 //
 886 // See ParallelCompactData for precise details.  The summary phase also
 887 // calculates the dense prefix for the compaction.  The dense prefix is a
 888 // portion at the beginning of the space that is not moved.  The objects in the
 889 // dense prefix do need to have their object references updated.  See method
 890 // summarize_dense_prefix().
 891 //
 892 // The summary phase is done using 1 GC thread.
 893 //
 894 // The compaction phase moves objects to their new location and updates all
 895 // references in the object.
 896 //
 897 // A current exception is that objects that cross a region boundary are moved
 898 // but do not have their references updated.  References are not updated because
 899 // it cannot easily be determined if the klass pointer KKK for the object AAA
 900 // has been updated.  KKK likely resides in a region to the left of the region
 901 // containing AAA.  These AAA's have there references updated at the end in a
 902 // clean up phase.  See the method PSParallelCompact::update_deferred_objects().
 903 // An alternate strategy is being investigated for this deferral of updating.
 904 //
 905 // Compaction is done on a region basis.  A region that is ready to be filled is
 906 // put on a ready list and GC threads take region off the list and fill them.  A
 907 // region is ready to be filled if it empty of live objects.  Such a region may
 908 // have been initially empty (only contained dead objects) or may have had all
 909 // its live objects copied out already.  A region that compacts into itself is
 910 // also ready for filling.  The ready list is initially filled with empty
 911 // regions and regions compacting into themselves.  There is always at least 1
 912 // region that can be put on the ready list.  The regions are atomically added
 913 // and removed from the ready list.
 914 
 915 class TaskQueue;
 916 
 917 class PSParallelCompact : AllStatic {
 918  public:
 919   // Convenient access to type names.
 920   typedef ParMarkBitMap::idx_t idx_t;
 921   typedef ParallelCompactData::RegionData RegionData;
 922   typedef ParallelCompactData::BlockData BlockData;
 923 
 924   typedef enum {
 925     old_space_id, eden_space_id,
 926     from_space_id, to_space_id, last_space_id
 927   } SpaceId;
 928 
 929   struct UpdateDensePrefixTask : public CHeapObj<mtGC> {
 930     SpaceId _space_id;
 931     size_t _region_index_start;
 932     size_t _region_index_end;
 933 
 934     UpdateDensePrefixTask() :
 935         _space_id(SpaceId(0)),
 936         _region_index_start(0),
 937         _region_index_end(0) {}
 938 
 939     UpdateDensePrefixTask(SpaceId space_id,
 940                           size_t region_index_start,
 941                           size_t region_index_end) :
 942         _space_id(space_id),
 943         _region_index_start(region_index_start),
 944         _region_index_end(region_index_end) {}
 945   };
 946 
 947  public:
 948   // Inline closure decls
 949   //
 950   class IsAliveClosure: public BoolObjectClosure {
 951    public:
 952     virtual bool do_object_b(oop p);
 953   };
 954 
 955   friend class RefProcTaskProxy;
 956   friend class PSParallelCompactTest;
 957 
 958  private:
 959   static STWGCTimer           _gc_timer;
 960   static ParallelOldTracer    _gc_tracer;
 961   static elapsedTimer         _accumulated_time;
 962   static unsigned int         _total_invocations;
 963   static unsigned int         _maximum_compaction_gc_num;
 964   static jlong                _time_of_last_gc;   // ms
 965   static CollectorCounters*   _counters;
 966   static ParMarkBitMap        _mark_bitmap;
 967   static ParallelCompactData  _summary_data;
 968   static IsAliveClosure       _is_alive_closure;
 969   static SpaceInfo            _space_info[last_space_id];
 970 
 971   // Reference processing (used in ...follow_contents)
 972   static SpanSubjectToDiscoveryClosure  _span_based_discoverer;
 973   static ReferenceProcessor*  _ref_processor;
 974 
 975   // Values computed at initialization and used by dead_wood_limiter().
 976   static double _dwl_mean;
 977   static double _dwl_std_dev;
 978   static double _dwl_first_term;
 979   static double _dwl_adjustment;
 980 #ifdef  ASSERT
 981   static bool   _dwl_initialized;
 982 #endif  // #ifdef ASSERT
 983 
 984  public:
 985   static ParallelOldTracer* gc_tracer() { return &_gc_tracer; }
 986 
 987  private:
 988 
 989   static void initialize_space_info();
 990 
 991   // Clear the marking bitmap and summary data that cover the specified space.
 992   static void clear_data_covering_space(SpaceId id);
 993 
 994   static void pre_compact();
 995   static void post_compact();
 996 
 997   // Mark live objects
 998   static void marking_phase(ParCompactionManager* cm,
 999                             bool maximum_heap_compaction,
1000                             ParallelOldTracer *gc_tracer);
1001 
1002   // Compute the dense prefix for the designated space.  This is an experimental
1003   // implementation currently not used in production.
1004   static HeapWord* compute_dense_prefix_via_density(const SpaceId id,
1005                                                     bool maximum_compaction);
1006 
1007   // Methods used to compute the dense prefix.
1008 
1009   // Compute the value of the normal distribution at x = density.  The mean and
1010   // standard deviation are values saved by initialize_dead_wood_limiter().
1011   static inline double normal_distribution(double density);
1012 
1013   // Initialize the static vars used by dead_wood_limiter().
1014   static void initialize_dead_wood_limiter();
1015 
1016   // Return the percentage of space that can be treated as "dead wood" (i.e.,
1017   // not reclaimed).
1018   static double dead_wood_limiter(double density, size_t min_percent);
1019 
1020   // Find the first (left-most) region in the range [beg, end) that has at least
1021   // dead_words of dead space to the left.  The argument beg must be the first
1022   // region in the space that is not completely live.
1023   static RegionData* dead_wood_limit_region(const RegionData* beg,
1024                                             const RegionData* end,
1025                                             size_t dead_words);
1026 
1027   // Return a pointer to the first region in the range [beg, end) that is not
1028   // completely full.
1029   static RegionData* first_dead_space_region(const RegionData* beg,
1030                                              const RegionData* end);
1031 
1032   // Return a value indicating the benefit or 'yield' if the compacted region
1033   // were to start (or equivalently if the dense prefix were to end) at the
1034   // candidate region.  Higher values are better.
1035   //
1036   // The value is based on the amount of space reclaimed vs. the costs of (a)
1037   // updating references in the dense prefix plus (b) copying objects and
1038   // updating references in the compacted region.
1039   static inline double reclaimed_ratio(const RegionData* const candidate,
1040                                        HeapWord* const bottom,
1041                                        HeapWord* const top,
1042                                        HeapWord* const new_top);
1043 
1044   // Compute the dense prefix for the designated space.
1045   static HeapWord* compute_dense_prefix(const SpaceId id,
1046                                         bool maximum_compaction);
1047 
1048   // Return true if dead space crosses onto the specified Region; bit must be
1049   // the bit index corresponding to the first word of the Region.
1050   static inline bool dead_space_crosses_boundary(const RegionData* region,
1051                                                  idx_t bit);
1052 
1053   // Summary phase utility routine to fill dead space (if any) at the dense
1054   // prefix boundary.  Should only be called if the the dense prefix is
1055   // non-empty.
1056   static void fill_dense_prefix_end(SpaceId id);
1057 
1058   static void summarize_spaces_quick();
1059   static void summarize_space(SpaceId id, bool maximum_compaction);
1060   static void summary_phase(ParCompactionManager* cm, bool maximum_compaction);
1061 
1062   // Adjust addresses in roots.  Does not adjust addresses in heap.
1063   static void adjust_roots(ParCompactionManager* cm);
1064 
1065   DEBUG_ONLY(static void write_block_fill_histogram();)
1066 
1067   // Move objects to new locations.
1068   static void compact_perm(ParCompactionManager* cm);
1069   static void compact();
1070 
1071   // Add available regions to the stack and draining tasks to the task queue.
1072   static void prepare_region_draining_tasks(uint parallel_gc_threads);
1073 
1074   // Add dense prefix update tasks to the task queue.
1075   static void enqueue_dense_prefix_tasks(TaskQueue& task_queue,
1076                                          uint parallel_gc_threads);
1077 
1078   // If objects are left in eden after a collection, try to move the boundary
1079   // and absorb them into the old gen.  Returns true if eden was emptied.
1080   static bool absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
1081                                          PSYoungGen* young_gen,
1082                                          PSOldGen* old_gen);
1083 
1084   // Reset time since last full gc
1085   static void reset_millis_since_last_gc();
1086 
1087 #ifndef PRODUCT
1088   // Print generic summary data
1089   static void print_generic_summary_data(ParallelCompactData& summary_data,
1090                                          HeapWord* const beg_addr,
1091                                          HeapWord* const end_addr);
1092 #endif  // #ifndef PRODUCT
1093 
1094  public:
1095 
1096   PSParallelCompact();
1097 
1098   static void invoke(bool maximum_heap_compaction);
1099   static bool invoke_no_policy(bool maximum_heap_compaction);
1100 
1101   static void post_initialize();
1102   // Perform initialization for PSParallelCompact that requires
1103   // allocations.  This should be called during the VM initialization
1104   // at a pointer where it would be appropriate to return a JNI_ENOMEM
1105   // in the event of a failure.
1106   static bool initialize();
1107 
1108   // Closure accessors
1109   static BoolObjectClosure* is_alive_closure()     { return (BoolObjectClosure*)&_is_alive_closure; }
1110 
1111   // Public accessors
1112   static elapsedTimer* accumulated_time() { return &_accumulated_time; }
1113   static unsigned int total_invocations() { return _total_invocations; }
1114   static CollectorCounters* counters()    { return _counters; }
1115 
1116   // Marking support
1117   static inline bool mark_obj(oop obj);
1118   static inline bool is_marked(oop obj);
1119 
1120   template <class T> static inline void adjust_pointer(T* p, ParCompactionManager* cm);
1121 
1122   // Compaction support.
1123   // Return true if p is in the range [beg_addr, end_addr).
1124   static inline bool is_in(HeapWord* p, HeapWord* beg_addr, HeapWord* end_addr);
1125   static inline bool is_in(oop* p, HeapWord* beg_addr, HeapWord* end_addr);
1126 
1127   // Convenience wrappers for per-space data kept in _space_info.
1128   static inline MutableSpace*     space(SpaceId space_id);
1129   static inline HeapWord*         new_top(SpaceId space_id);
1130   static inline HeapWord*         dense_prefix(SpaceId space_id);
1131   static inline ObjectStartArray* start_array(SpaceId space_id);
1132 
1133   // Process the end of the given region range in the dense prefix.
1134   // This includes saving any object not updated.
1135   static void dense_prefix_regions_epilogue(ParCompactionManager* cm,
1136                                             size_t region_start_index,
1137                                             size_t region_end_index,
1138                                             idx_t exiting_object_offset,
1139                                             idx_t region_offset_start,
1140                                             idx_t region_offset_end);
1141 
1142   // Update a region in the dense prefix.  For each live object
1143   // in the region, update it's interior references.  For each
1144   // dead object, fill it with deadwood. Dead space at the end
1145   // of a region range will be filled to the start of the next
1146   // live object regardless of the region_index_end.  None of the
1147   // objects in the dense prefix move and dead space is dead
1148   // (holds only dead objects that don't need any processing), so
1149   // dead space can be filled in any order.
1150   static void update_and_deadwood_in_dense_prefix(ParCompactionManager* cm,
1151                                                   SpaceId space_id,
1152                                                   size_t region_index_start,
1153                                                   size_t region_index_end);
1154 
1155   // Return the address of the count + 1st live word in the range [beg, end).
1156   static HeapWord* skip_live_words(HeapWord* beg, HeapWord* end, size_t count);
1157 
1158   // Return the address of the word to be copied to dest_addr, which must be
1159   // aligned to a region boundary.
1160   static HeapWord* first_src_addr(HeapWord* const dest_addr,
1161                                   SpaceId src_space_id,
1162                                   size_t src_region_idx);
1163 
1164   // Determine the next source region, set closure.source() to the start of the
1165   // new region return the region index.  Parameter end_addr is the address one
1166   // beyond the end of source range just processed.  If necessary, switch to a
1167   // new source space and set src_space_id (in-out parameter) and src_space_top
1168   // (out parameter) accordingly.
1169   static size_t next_src_region(MoveAndUpdateClosure& closure,
1170                                 SpaceId& src_space_id,
1171                                 HeapWord*& src_space_top,
1172                                 HeapWord* end_addr);
1173 
1174   // Decrement the destination count for each non-empty source region in the
1175   // range [beg_region, region(region_align_up(end_addr))).  If the destination
1176   // count for a region goes to 0 and it needs to be filled, enqueue it.
1177   static void decrement_destination_counts(ParCompactionManager* cm,
1178                                            SpaceId src_space_id,
1179                                            size_t beg_region,
1180                                            HeapWord* end_addr);
1181 
1182   // Fill a region, copying objects from one or more source regions.
1183   static void fill_region(ParCompactionManager* cm, size_t region_idx);
1184   static void fill_and_update_region(ParCompactionManager* cm, size_t region) {
1185     fill_region(cm, region);
1186   }
1187 
1188   // Fill in the block table for the specified region.
1189   static void fill_blocks(size_t region_idx);
1190 
1191   // Update the deferred objects in the space.
1192   static void update_deferred_objects(ParCompactionManager* cm, SpaceId id);
1193 
1194   static ParMarkBitMap* mark_bitmap() { return &_mark_bitmap; }
1195   static ParallelCompactData& summary_data() { return _summary_data; }
1196 
1197   // Reference Processing
1198   static ReferenceProcessor* const ref_processor() { return _ref_processor; }
1199 
1200   static STWGCTimer* gc_timer() { return &_gc_timer; }
1201 
1202   // Return the SpaceId for the given address.
1203   static SpaceId space_id(HeapWord* addr);
1204 
1205   // Time since last full gc (in milliseconds).
1206   static jlong millis_since_last_gc();
1207 
1208   static void print_on_error(outputStream* st);
1209 
1210 #ifndef PRODUCT
1211   // Debugging support.
1212   static const char* space_names[last_space_id];
1213   static void print_region_ranges();
1214   static void print_dense_prefix_stats(const char* const algorithm,
1215                                        const SpaceId id,
1216                                        const bool maximum_compaction,
1217                                        HeapWord* const addr);
1218   static void summary_phase_msg(SpaceId dst_space_id,
1219                                 HeapWord* dst_beg, HeapWord* dst_end,
1220                                 SpaceId src_space_id,
1221                                 HeapWord* src_beg, HeapWord* src_end);
1222 #endif  // #ifndef PRODUCT
1223 
1224 #ifdef  ASSERT
1225   // Sanity check the new location of a word in the heap.
1226   static inline void check_new_location(HeapWord* old_addr, HeapWord* new_addr);
1227   // Verify that all the regions have been emptied.
1228   static void verify_complete(SpaceId space_id);
1229 #endif  // #ifdef ASSERT
1230 };
1231 
1232 class MoveAndUpdateClosure: public ParMarkBitMapClosure {
1233  public:
1234   inline MoveAndUpdateClosure(ParMarkBitMap* bitmap, ParCompactionManager* cm,
1235                               ObjectStartArray* start_array,
1236                               HeapWord* destination, size_t words);
1237 
1238   // Accessors.
1239   HeapWord* destination() const         { return _destination; }
1240 
1241   // If the object will fit (size <= words_remaining()), copy it to the current
1242   // destination, update the interior oops and the start array and return either
1243   // full (if the closure is full) or incomplete.  If the object will not fit,
1244   // return would_overflow.
1245   virtual IterationStatus do_addr(HeapWord* addr, size_t size);
1246 
1247   // Copy enough words to fill this closure, starting at source().  Interior
1248   // oops and the start array are not updated.  Return full.
1249   IterationStatus copy_until_full();
1250 
1251   // Copy enough words to fill this closure or to the end of an object,
1252   // whichever is smaller, starting at source().  Interior oops and the start
1253   // array are not updated.
1254   void copy_partial_obj();
1255 
1256  protected:
1257   // Update variables to indicate that word_count words were processed.
1258   inline void update_state(size_t word_count);
1259 
1260  protected:
1261   ObjectStartArray* const _start_array;
1262   HeapWord*               _destination;         // Next addr to be written.
1263 };
1264 
1265 inline
1266 MoveAndUpdateClosure::MoveAndUpdateClosure(ParMarkBitMap* bitmap,
1267                                            ParCompactionManager* cm,
1268                                            ObjectStartArray* start_array,
1269                                            HeapWord* destination,
1270                                            size_t words) :
1271   ParMarkBitMapClosure(bitmap, cm, words), _start_array(start_array)
1272 {
1273   _destination = destination;
1274 }
1275 
1276 inline void MoveAndUpdateClosure::update_state(size_t words)
1277 {
1278   decrement_words_remaining(words);
1279   _source += words;
1280   _destination += words;
1281 }
1282 
1283 class UpdateOnlyClosure: public ParMarkBitMapClosure {
1284  private:
1285   const PSParallelCompact::SpaceId _space_id;
1286   ObjectStartArray* const          _start_array;
1287 
1288  public:
1289   UpdateOnlyClosure(ParMarkBitMap* mbm,
1290                     ParCompactionManager* cm,
1291                     PSParallelCompact::SpaceId space_id);
1292 
1293   // Update the object.
1294   virtual IterationStatus do_addr(HeapWord* addr, size_t words);
1295 
1296   inline void do_addr(HeapWord* addr);
1297 };
1298 
1299 class FillClosure: public ParMarkBitMapClosure {
1300  public:
1301   FillClosure(ParCompactionManager* cm, PSParallelCompact::SpaceId space_id);
1302 
1303   virtual IterationStatus do_addr(HeapWord* addr, size_t size);
1304 
1305  private:
1306   ObjectStartArray* const _start_array;
1307 };
1308 
1309 #endif // SHARE_GC_PARALLEL_PSPARALLELCOMPACT_HPP