1 /*
   2  * Copyright (c) 2005, 2017, Oracle and/or its affiliates. All rights reserved.
   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.
   8  *
   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  *
  15  * You should have received a copy of the GNU General Public License version
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  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
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  24 
  25 #ifndef SHARE_VM_GC_PARALLEL_PSPARALLELCOMPACT_HPP
  26 #define SHARE_VM_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 GCTaskManager;
  44 class GCTaskQueue;
  45 class PreGCValues;
  46 class MoveAndUpdateClosure;
  47 class RefProcTaskExecutor;
  48 class ParallelOldTracer;
  49 class STWGCTimer;
  50 
  51 // The SplitInfo class holds the information needed to 'split' a source region
  52 // so that the live data can be copied to two destination *spaces*.  Normally,
  53 // all the live data in a region is copied to a single destination space (e.g.,
  54 // everything live in a region in eden is copied entirely into the old gen).
  55 // However, when the heap is nearly full, all the live data in eden may not fit
  56 // into the old gen.  Copying only some of the regions from eden to old gen
  57 // requires finding a region that does not contain a partial object (i.e., no
  58 // live object crosses the region boundary) somewhere near the last object that
  59 // does fit into the old gen.  Since it's not always possible to find such a
  60 // region, splitting is necessary for predictable behavior.
  61 //
  62 // A region is always split at the end of the partial object.  This avoids
  63 // additional tests when calculating the new location of a pointer, which is a
  64 // very hot code path.  The partial object and everything to its left will be
  65 // copied to another space (call it dest_space_1).  The live data to the right
  66 // of the partial object will be copied either within the space itself, or to a
  67 // different destination space (distinct from dest_space_1).
  68 //
  69 // Split points are identified during the summary phase, when region
  70 // destinations are computed:  data about the split, including the
  71 // partial_object_size, is recorded in a SplitInfo record and the
  72 // partial_object_size field in the summary data is set to zero.  The zeroing is
  73 // possible (and necessary) since the partial object will move to a different
  74 // destination space than anything to its right, thus the partial object should
  75 // not affect the locations of any objects to its right.
  76 //
  77 // The recorded data is used during the compaction phase, but only rarely:  when
  78 // the partial object on the split region will be copied across a destination
  79 // region boundary.  This test is made once each time a region is filled, and is
  80 // a simple address comparison, so the overhead is negligible (see
  81 // PSParallelCompact::first_src_addr()).
  82 //
  83 // Notes:
  84 //
  85 // Only regions with partial objects are split; a region without a partial
  86 // object does not need any extra bookkeeping.
  87 //
  88 // At most one region is split per space, so the amount of data required is
  89 // constant.
  90 //
  91 // A region is split only when the destination space would overflow.  Once that
  92 // happens, the destination space is abandoned and no other data (even from
  93 // other source spaces) is targeted to that destination space.  Abandoning the
  94 // destination space may leave a somewhat large unused area at the end, if a
  95 // large object caused the overflow.
  96 //
  97 // Future work:
  98 //
  99 // More bookkeeping would be required to continue to use the destination space.
 100 // The most general solution would allow data from regions in two different
 101 // source spaces to be "joined" in a single destination region.  At the very
 102 // least, additional code would be required in next_src_region() to detect the
 103 // join and skip to an out-of-order source region.  If the join region was also
 104 // the last destination region to which a split region was copied (the most
 105 // likely case), then additional work would be needed to get fill_region() to
 106 // stop iteration and switch to a new source region at the right point.  Basic
 107 // idea would be to use a fake value for the top of the source space.  It is
 108 // doable, if a bit tricky.
 109 //
 110 // A simpler (but less general) solution would fill the remainder of the
 111 // destination region with a dummy object and continue filling the next
 112 // destination region.
 113 
 114 class SplitInfo
 115 {
 116 public:
 117   // Return true if this split info is valid (i.e., if a split has been
 118   // recorded).  The very first region cannot have a partial object and thus is
 119   // never split, so 0 is the 'invalid' value.
 120   bool is_valid() const { return _src_region_idx > 0; }
 121 
 122   // Return true if this split holds data for the specified source region.
 123   inline bool is_split(size_t source_region) const;
 124 
 125   // The index of the split region, the size of the partial object on that
 126   // region and the destination of the partial object.
 127   size_t    src_region_idx() const   { return _src_region_idx; }
 128   size_t    partial_obj_size() const { return _partial_obj_size; }
 129   HeapWord* destination() const      { return _destination; }
 130 
 131   // The destination count of the partial object referenced by this split
 132   // (either 1 or 2).  This must be added to the destination count of the
 133   // remainder of the source region.
 134   unsigned int destination_count() const { return _destination_count; }
 135 
 136   // If a word within the partial object will be written to the first word of a
 137   // destination region, this is the address of the destination region;
 138   // otherwise this is NULL.
 139   HeapWord* dest_region_addr() const     { return _dest_region_addr; }
 140 
 141   // If a word within the partial object will be written to the first word of a
 142   // destination region, this is the address of that word within the partial
 143   // object; otherwise this is NULL.
 144   HeapWord* first_src_addr() const       { return _first_src_addr; }
 145 
 146   // Record the data necessary to split the region src_region_idx.
 147   void record(size_t src_region_idx, size_t partial_obj_size,
 148               HeapWord* destination);
 149 
 150   void clear();
 151 
 152   DEBUG_ONLY(void verify_clear();)
 153 
 154 private:
 155   size_t       _src_region_idx;
 156   size_t       _partial_obj_size;
 157   HeapWord*    _destination;
 158   unsigned int _destination_count;
 159   HeapWord*    _dest_region_addr;
 160   HeapWord*    _first_src_addr;
 161 };
 162 
 163 inline bool SplitInfo::is_split(size_t region_idx) const
 164 {
 165   return _src_region_idx == region_idx && is_valid();
 166 }
 167 
 168 class SpaceInfo
 169 {
 170  public:
 171   MutableSpace* space() const { return _space; }
 172 
 173   // Where the free space will start after the collection.  Valid only after the
 174   // summary phase completes.
 175   HeapWord* new_top() const { return _new_top; }
 176 
 177   // Allows new_top to be set.
 178   HeapWord** new_top_addr() { return &_new_top; }
 179 
 180   // Where the smallest allowable dense prefix ends (used only for perm gen).
 181   HeapWord* min_dense_prefix() const { return _min_dense_prefix; }
 182 
 183   // Where the dense prefix ends, or the compacted region begins.
 184   HeapWord* dense_prefix() const { return _dense_prefix; }
 185 
 186   // The start array for the (generation containing the) space, or NULL if there
 187   // is no start array.
 188   ObjectStartArray* start_array() const { return _start_array; }
 189 
 190   SplitInfo& split_info() { return _split_info; }
 191 
 192   void set_space(MutableSpace* s)           { _space = s; }
 193   void set_new_top(HeapWord* addr)          { _new_top = addr; }
 194   void set_min_dense_prefix(HeapWord* addr) { _min_dense_prefix = addr; }
 195   void set_dense_prefix(HeapWord* addr)     { _dense_prefix = addr; }
 196   void set_start_array(ObjectStartArray* s) { _start_array = s; }
 197 
 198   void publish_new_top() const              { _space->set_top(_new_top); }
 199 
 200  private:
 201   MutableSpace*     _space;
 202   HeapWord*         _new_top;
 203   HeapWord*         _min_dense_prefix;
 204   HeapWord*         _dense_prefix;
 205   ObjectStartArray* _start_array;
 206   SplitInfo         _split_info;
 207 };
 208 
 209 class ParallelCompactData
 210 {
 211 public:
 212   // Sizes are in HeapWords, unless indicated otherwise.
 213   static const size_t Log2RegionSize;
 214   static const size_t RegionSize;
 215   static const size_t RegionSizeBytes;
 216 
 217   // Mask for the bits in a size_t to get an offset within a region.
 218   static const size_t RegionSizeOffsetMask;
 219   // Mask for the bits in a pointer to get an offset within a region.
 220   static const size_t RegionAddrOffsetMask;
 221   // Mask for the bits in a pointer to get the address of the start of a region.
 222   static const size_t RegionAddrMask;
 223 
 224   static const size_t Log2BlockSize;
 225   static const size_t BlockSize;
 226   static const size_t BlockSizeBytes;
 227 
 228   static const size_t BlockSizeOffsetMask;
 229   static const size_t BlockAddrOffsetMask;
 230   static const size_t BlockAddrMask;
 231 
 232   static const size_t BlocksPerRegion;
 233   static const size_t Log2BlocksPerRegion;
 234 
 235   class RegionData
 236   {
 237   public:
 238     // Destination address of the region.
 239     HeapWord* destination() const { return _destination; }
 240 
 241     // The first region containing data destined for this region.
 242     size_t source_region() const { return _source_region; }
 243 
 244     // The object (if any) starting in this region and ending in a different
 245     // region that could not be updated during the main (parallel) compaction
 246     // phase.  This is different from _partial_obj_addr, which is an object that
 247     // extends onto a source region.  However, the two uses do not overlap in
 248     // time, so the same field is used to save space.
 249     HeapWord* deferred_obj_addr() const { return _partial_obj_addr; }
 250 
 251     // The starting address of the partial object extending onto the region.
 252     HeapWord* partial_obj_addr() const { return _partial_obj_addr; }
 253 
 254     // Size of the partial object extending onto the region (words).
 255     size_t partial_obj_size() const { return _partial_obj_size; }
 256 
 257     // Size of live data that lies within this region due to objects that start
 258     // in this region (words).  This does not include the partial object
 259     // extending onto the region (if any), or the part of an object that extends
 260     // onto the next region (if any).
 261     size_t live_obj_size() const { return _dc_and_los & los_mask; }
 262 
 263     // Total live data that lies within the region (words).
 264     size_t data_size() const { return partial_obj_size() + live_obj_size(); }
 265 
 266     // The destination_count is the number of other regions to which data from
 267     // this region will be copied.  At the end of the summary phase, the valid
 268     // values of destination_count are
 269     //
 270     // 0 - data from the region will be compacted completely into itself, or the
 271     //     region is empty.  The region can be claimed and then filled.
 272     // 1 - data from the region will be compacted into 1 other region; some
 273     //     data from the region may also be compacted into the region itself.
 274     // 2 - data from the region will be copied to 2 other regions.
 275     //
 276     // During compaction as regions are emptied, the destination_count is
 277     // decremented (atomically) and when it reaches 0, it can be claimed and
 278     // then filled.
 279     //
 280     // A region is claimed for processing by atomically changing the
 281     // destination_count to the claimed value (dc_claimed).  After a region has
 282     // been filled, the destination_count should be set to the completed value
 283     // (dc_completed).
 284     inline uint destination_count() const;
 285     inline uint destination_count_raw() const;
 286 
 287     // Whether the block table for this region has been filled.
 288     inline bool blocks_filled() const;
 289 
 290     // Number of times the block table was filled.
 291     DEBUG_ONLY(inline size_t blocks_filled_count() const;)
 292 
 293     // The location of the java heap data that corresponds to this region.
 294     inline HeapWord* data_location() const;
 295 
 296     // The highest address referenced by objects in this region.
 297     inline HeapWord* highest_ref() const;
 298 
 299     // Whether this region is available to be claimed, has been claimed, or has
 300     // been completed.
 301     //
 302     // Minor subtlety:  claimed() returns true if the region is marked
 303     // completed(), which is desirable since a region must be claimed before it
 304     // can be completed.
 305     bool available() const { return _dc_and_los < dc_one; }
 306     bool claimed()   const { return _dc_and_los >= dc_claimed; }
 307     bool completed() const { return _dc_and_los >= dc_completed; }
 308 
 309     // These are not atomic.
 310     void set_destination(HeapWord* addr)       { _destination = addr; }
 311     void set_source_region(size_t region)      { _source_region = region; }
 312     void set_deferred_obj_addr(HeapWord* addr) { _partial_obj_addr = addr; }
 313     void set_partial_obj_addr(HeapWord* addr)  { _partial_obj_addr = addr; }
 314     void set_partial_obj_size(size_t words)    {
 315       _partial_obj_size = (region_sz_t) words;
 316     }
 317     inline void set_blocks_filled();
 318 
 319     inline void set_destination_count(uint count);
 320     inline void set_live_obj_size(size_t words);
 321     inline void set_data_location(HeapWord* addr);
 322     inline void set_completed();
 323     inline bool claim_unsafe();
 324 
 325     // These are atomic.
 326     inline void add_live_obj(size_t words);
 327     inline void set_highest_ref(HeapWord* addr);
 328     inline void decrement_destination_count();
 329     inline bool claim();
 330 
 331   private:
 332     // The type used to represent object sizes within a region.
 333     typedef uint region_sz_t;
 334 
 335     // Constants for manipulating the _dc_and_los field, which holds both the
 336     // destination count and live obj size.  The live obj size lives at the
 337     // least significant end so no masking is necessary when adding.
 338     static const region_sz_t dc_shift;           // Shift amount.
 339     static const region_sz_t dc_mask;            // Mask for destination count.
 340     static const region_sz_t dc_one;             // 1, shifted appropriately.
 341     static const region_sz_t dc_claimed;         // Region has been claimed.
 342     static const region_sz_t dc_completed;       // Region has been completed.
 343     static const region_sz_t los_mask;           // Mask for live obj size.
 344 
 345     HeapWord*            _destination;
 346     size_t               _source_region;
 347     HeapWord*            _partial_obj_addr;
 348     region_sz_t          _partial_obj_size;
 349     region_sz_t volatile _dc_and_los;
 350     bool        volatile _blocks_filled;
 351 
 352 #ifdef ASSERT
 353     size_t               _blocks_filled_count;   // Number of block table fills.
 354 
 355     // These enable optimizations that are only partially implemented.  Use
 356     // debug builds to prevent the code fragments from breaking.
 357     HeapWord*            _data_location;
 358     HeapWord*            _highest_ref;
 359 #endif  // #ifdef ASSERT
 360 
 361 #ifdef ASSERT
 362    public:
 363     uint                 _pushed;   // 0 until region is pushed onto a stack
 364    private:
 365 #endif
 366   };
 367 
 368   // "Blocks" allow shorter sections of the bitmap to be searched.  Each Block
 369   // holds an offset, which is the amount of live data in the Region to the left
 370   // of the first live object that starts in the Block.
 371   class BlockData
 372   {
 373   public:
 374     typedef unsigned short int blk_ofs_t;
 375 
 376     blk_ofs_t offset() const    { return _offset; }
 377     void set_offset(size_t val) { _offset = (blk_ofs_t)val; }
 378 
 379   private:
 380     blk_ofs_t _offset;
 381   };
 382 
 383 public:
 384   ParallelCompactData();
 385   bool initialize(MemRegion covered_region);
 386 
 387   size_t region_count() const { return _region_count; }
 388   size_t reserved_byte_size() const { return _reserved_byte_size; }
 389 
 390   // Convert region indices to/from RegionData pointers.
 391   inline RegionData* region(size_t region_idx) const;
 392   inline size_t     region(const RegionData* const region_ptr) const;
 393 
 394   size_t block_count() const { return _block_count; }
 395   inline BlockData* block(size_t block_idx) const;
 396   inline size_t     block(const BlockData* block_ptr) const;
 397 
 398   void add_obj(HeapWord* addr, size_t len);
 399   void add_obj(oop p, size_t len) { add_obj((HeapWord*)p, len); }
 400 
 401   // Fill in the regions covering [beg, end) so that no data moves; i.e., the
 402   // destination of region n is simply the start of region n.  The argument beg
 403   // must be region-aligned; end need not be.
 404   void summarize_dense_prefix(HeapWord* beg, HeapWord* end);
 405 
 406   HeapWord* summarize_split_space(size_t src_region, SplitInfo& split_info,
 407                                   HeapWord* destination, HeapWord* target_end,
 408                                   HeapWord** target_next);
 409   bool summarize(SplitInfo& split_info,
 410                  HeapWord* source_beg, HeapWord* source_end,
 411                  HeapWord** source_next,
 412                  HeapWord* target_beg, HeapWord* target_end,
 413                  HeapWord** target_next);
 414 
 415   void clear();
 416   void clear_range(size_t beg_region, size_t end_region);
 417   void clear_range(HeapWord* beg, HeapWord* end) {
 418     clear_range(addr_to_region_idx(beg), addr_to_region_idx(end));
 419   }
 420 
 421   // Return the number of words between addr and the start of the region
 422   // containing addr.
 423   inline size_t     region_offset(const HeapWord* addr) const;
 424 
 425   // Convert addresses to/from a region index or region pointer.
 426   inline size_t     addr_to_region_idx(const HeapWord* addr) const;
 427   inline RegionData* addr_to_region_ptr(const HeapWord* addr) const;
 428   inline HeapWord*  region_to_addr(size_t region) const;
 429   inline HeapWord*  region_to_addr(size_t region, size_t offset) const;
 430   inline HeapWord*  region_to_addr(const RegionData* region) const;
 431 
 432   inline HeapWord*  region_align_down(HeapWord* addr) const;
 433   inline HeapWord*  region_align_up(HeapWord* addr) const;
 434   inline bool       is_region_aligned(HeapWord* addr) const;
 435 
 436   // Analogous to region_offset() for blocks.
 437   size_t     block_offset(const HeapWord* addr) const;
 438   size_t     addr_to_block_idx(const HeapWord* addr) const;
 439   size_t     addr_to_block_idx(const oop obj) const {
 440     return addr_to_block_idx((HeapWord*) obj);
 441   }
 442   inline BlockData* addr_to_block_ptr(const HeapWord* addr) const;
 443   inline HeapWord*  block_to_addr(size_t block) const;
 444   inline size_t     region_to_block_idx(size_t region) const;
 445 
 446   inline HeapWord*  block_align_down(HeapWord* addr) const;
 447   inline HeapWord*  block_align_up(HeapWord* addr) const;
 448   inline bool       is_block_aligned(HeapWord* addr) const;
 449 
 450   // Return the address one past the end of the partial object.
 451   HeapWord* partial_obj_end(size_t region_idx) const;
 452 
 453   // Return the location of the object after compaction.
 454   HeapWord* calc_new_pointer(HeapWord* addr, ParCompactionManager* cm);
 455 
 456   HeapWord* calc_new_pointer(oop p, ParCompactionManager* cm) {
 457     return calc_new_pointer((HeapWord*) p, cm);
 458   }
 459 
 460 #ifdef  ASSERT
 461   void verify_clear(const PSVirtualSpace* vspace);
 462   void verify_clear();
 463 #endif  // #ifdef ASSERT
 464 
 465 private:
 466   bool initialize_block_data();
 467   bool initialize_region_data(size_t region_size);
 468   PSVirtualSpace* create_vspace(size_t count, size_t element_size);
 469 
 470 private:
 471   HeapWord*       _region_start;
 472 #ifdef  ASSERT
 473   HeapWord*       _region_end;
 474 #endif  // #ifdef ASSERT
 475 
 476   PSVirtualSpace* _region_vspace;
 477   size_t          _reserved_byte_size;
 478   RegionData*     _region_data;
 479   size_t          _region_count;
 480 
 481   PSVirtualSpace* _block_vspace;
 482   BlockData*      _block_data;
 483   size_t          _block_count;
 484 };
 485 
 486 inline uint
 487 ParallelCompactData::RegionData::destination_count_raw() const
 488 {
 489   return _dc_and_los & dc_mask;
 490 }
 491 
 492 inline uint
 493 ParallelCompactData::RegionData::destination_count() const
 494 {
 495   return destination_count_raw() >> dc_shift;
 496 }
 497 
 498 inline bool
 499 ParallelCompactData::RegionData::blocks_filled() const
 500 {
 501   bool result = _blocks_filled;
 502   OrderAccess::acquire();
 503   return result;
 504 }
 505 
 506 #ifdef ASSERT
 507 inline size_t
 508 ParallelCompactData::RegionData::blocks_filled_count() const
 509 {
 510   return _blocks_filled_count;
 511 }
 512 #endif // #ifdef ASSERT
 513 
 514 inline void
 515 ParallelCompactData::RegionData::set_blocks_filled()
 516 {
 517   OrderAccess::release();
 518   _blocks_filled = true;
 519   // Debug builds count the number of times the table was filled.
 520   DEBUG_ONLY(Atomic::inc(&_blocks_filled_count));
 521 }
 522 
 523 inline void
 524 ParallelCompactData::RegionData::set_destination_count(uint count)
 525 {
 526   assert(count <= (dc_completed >> dc_shift), "count too large");
 527   const region_sz_t live_sz = (region_sz_t) live_obj_size();
 528   _dc_and_los = (count << dc_shift) | live_sz;
 529 }
 530 
 531 inline void ParallelCompactData::RegionData::set_live_obj_size(size_t words)
 532 {
 533   assert(words <= los_mask, "would overflow");
 534   _dc_and_los = destination_count_raw() | (region_sz_t)words;
 535 }
 536 
 537 inline void ParallelCompactData::RegionData::decrement_destination_count()
 538 {
 539   assert(_dc_and_los < dc_claimed, "already claimed");
 540   assert(_dc_and_los >= dc_one, "count would go negative");
 541   Atomic::add((int)dc_mask, (volatile int*)&_dc_and_los);
 542 }
 543 
 544 inline HeapWord* ParallelCompactData::RegionData::data_location() const
 545 {
 546   DEBUG_ONLY(return _data_location;)
 547   NOT_DEBUG(return NULL;)
 548 }
 549 
 550 inline HeapWord* ParallelCompactData::RegionData::highest_ref() const
 551 {
 552   DEBUG_ONLY(return _highest_ref;)
 553   NOT_DEBUG(return NULL;)
 554 }
 555 
 556 inline void ParallelCompactData::RegionData::set_data_location(HeapWord* addr)
 557 {
 558   DEBUG_ONLY(_data_location = addr;)
 559 }
 560 
 561 inline void ParallelCompactData::RegionData::set_completed()
 562 {
 563   assert(claimed(), "must be claimed first");
 564   _dc_and_los = dc_completed | (region_sz_t) live_obj_size();
 565 }
 566 
 567 // MT-unsafe claiming of a region.  Should only be used during single threaded
 568 // execution.
 569 inline bool ParallelCompactData::RegionData::claim_unsafe()
 570 {
 571   if (available()) {
 572     _dc_and_los |= dc_claimed;
 573     return true;
 574   }
 575   return false;
 576 }
 577 
 578 inline void ParallelCompactData::RegionData::add_live_obj(size_t words)
 579 {
 580   assert(words <= (size_t)los_mask - live_obj_size(), "overflow");
 581   Atomic::add((int) words, (volatile int*) &_dc_and_los);
 582 }
 583 
 584 inline void ParallelCompactData::RegionData::set_highest_ref(HeapWord* addr)
 585 {
 586 #ifdef ASSERT
 587   HeapWord* tmp = _highest_ref;
 588   while (addr > tmp) {
 589     tmp = Atomic::cmpxchg(addr, &_highest_ref, tmp);
 590   }
 591 #endif  // #ifdef ASSERT
 592 }
 593 
 594 inline bool ParallelCompactData::RegionData::claim()
 595 {
 596   const region_sz_t los = static_cast<region_sz_t>(live_obj_size());
 597   const region_sz_t old = Atomic::cmpxchg(dc_claimed | los, &_dc_and_los, los);
 598   return old == los;
 599 }
 600 
 601 inline ParallelCompactData::RegionData*
 602 ParallelCompactData::region(size_t region_idx) const
 603 {
 604   assert(region_idx <= region_count(), "bad arg");
 605   return _region_data + region_idx;
 606 }
 607 
 608 inline size_t
 609 ParallelCompactData::region(const RegionData* const region_ptr) const
 610 {
 611   assert(region_ptr >= _region_data, "bad arg");
 612   assert(region_ptr <= _region_data + region_count(), "bad arg");
 613   return pointer_delta(region_ptr, _region_data, sizeof(RegionData));
 614 }
 615 
 616 inline ParallelCompactData::BlockData*
 617 ParallelCompactData::block(size_t n) const {
 618   assert(n < block_count(), "bad arg");
 619   return _block_data + n;
 620 }
 621 
 622 inline size_t
 623 ParallelCompactData::region_offset(const HeapWord* addr) const
 624 {
 625   assert(addr >= _region_start, "bad addr");
 626   assert(addr <= _region_end, "bad addr");
 627   return (size_t(addr) & RegionAddrOffsetMask) >> LogHeapWordSize;
 628 }
 629 
 630 inline size_t
 631 ParallelCompactData::addr_to_region_idx(const HeapWord* addr) const
 632 {
 633   assert(addr >= _region_start, "bad addr " PTR_FORMAT " _region_start " PTR_FORMAT, p2i(addr), p2i(_region_start));
 634   assert(addr <= _region_end, "bad addr " PTR_FORMAT " _region_end " PTR_FORMAT, p2i(addr), p2i(_region_end));
 635   return pointer_delta(addr, _region_start) >> Log2RegionSize;
 636 }
 637 
 638 inline ParallelCompactData::RegionData*
 639 ParallelCompactData::addr_to_region_ptr(const HeapWord* addr) const
 640 {
 641   return region(addr_to_region_idx(addr));
 642 }
 643 
 644 inline HeapWord*
 645 ParallelCompactData::region_to_addr(size_t region) const
 646 {
 647   assert(region <= _region_count, "region out of range");
 648   return _region_start + (region << Log2RegionSize);
 649 }
 650 
 651 inline HeapWord*
 652 ParallelCompactData::region_to_addr(const RegionData* region) const
 653 {
 654   return region_to_addr(pointer_delta(region, _region_data,
 655                                       sizeof(RegionData)));
 656 }
 657 
 658 inline HeapWord*
 659 ParallelCompactData::region_to_addr(size_t region, size_t offset) const
 660 {
 661   assert(region <= _region_count, "region out of range");
 662   assert(offset < RegionSize, "offset too big");  // This may be too strict.
 663   return region_to_addr(region) + offset;
 664 }
 665 
 666 inline HeapWord*
 667 ParallelCompactData::region_align_down(HeapWord* addr) const
 668 {
 669   assert(addr >= _region_start, "bad addr");
 670   assert(addr < _region_end + RegionSize, "bad addr");
 671   return (HeapWord*)(size_t(addr) & RegionAddrMask);
 672 }
 673 
 674 inline HeapWord*
 675 ParallelCompactData::region_align_up(HeapWord* addr) const
 676 {
 677   assert(addr >= _region_start, "bad addr");
 678   assert(addr <= _region_end, "bad addr");
 679   return region_align_down(addr + RegionSizeOffsetMask);
 680 }
 681 
 682 inline bool
 683 ParallelCompactData::is_region_aligned(HeapWord* addr) const
 684 {
 685   return region_offset(addr) == 0;
 686 }
 687 
 688 inline size_t
 689 ParallelCompactData::block_offset(const HeapWord* addr) const
 690 {
 691   assert(addr >= _region_start, "bad addr");
 692   assert(addr <= _region_end, "bad addr");
 693   return (size_t(addr) & BlockAddrOffsetMask) >> LogHeapWordSize;
 694 }
 695 
 696 inline size_t
 697 ParallelCompactData::addr_to_block_idx(const HeapWord* addr) const
 698 {
 699   assert(addr >= _region_start, "bad addr");
 700   assert(addr <= _region_end, "bad addr");
 701   return pointer_delta(addr, _region_start) >> Log2BlockSize;
 702 }
 703 
 704 inline ParallelCompactData::BlockData*
 705 ParallelCompactData::addr_to_block_ptr(const HeapWord* addr) const
 706 {
 707   return block(addr_to_block_idx(addr));
 708 }
 709 
 710 inline HeapWord*
 711 ParallelCompactData::block_to_addr(size_t block) const
 712 {
 713   assert(block < _block_count, "block out of range");
 714   return _region_start + (block << Log2BlockSize);
 715 }
 716 
 717 inline size_t
 718 ParallelCompactData::region_to_block_idx(size_t region) const
 719 {
 720   return region << Log2BlocksPerRegion;
 721 }
 722 
 723 inline HeapWord*
 724 ParallelCompactData::block_align_down(HeapWord* addr) const
 725 {
 726   assert(addr >= _region_start, "bad addr");
 727   assert(addr < _region_end + RegionSize, "bad addr");
 728   return (HeapWord*)(size_t(addr) & BlockAddrMask);
 729 }
 730 
 731 inline HeapWord*
 732 ParallelCompactData::block_align_up(HeapWord* addr) const
 733 {
 734   assert(addr >= _region_start, "bad addr");
 735   assert(addr <= _region_end, "bad addr");
 736   return block_align_down(addr + BlockSizeOffsetMask);
 737 }
 738 
 739 inline bool
 740 ParallelCompactData::is_block_aligned(HeapWord* addr) const
 741 {
 742   return block_offset(addr) == 0;
 743 }
 744 
 745 // Abstract closure for use with ParMarkBitMap::iterate(), which will invoke the
 746 // do_addr() method.
 747 //
 748 // The closure is initialized with the number of heap words to process
 749 // (words_remaining()), and becomes 'full' when it reaches 0.  The do_addr()
 750 // methods in subclasses should update the total as words are processed.  Since
 751 // only one subclass actually uses this mechanism to terminate iteration, the
 752 // default initial value is > 0.  The implementation is here and not in the
 753 // single subclass that uses it to avoid making is_full() virtual, and thus
 754 // adding a virtual call per live object.
 755 
 756 class ParMarkBitMapClosure: public StackObj {
 757  public:
 758   typedef ParMarkBitMap::idx_t idx_t;
 759   typedef ParMarkBitMap::IterationStatus IterationStatus;
 760 
 761  public:
 762   inline ParMarkBitMapClosure(ParMarkBitMap* mbm, ParCompactionManager* cm,
 763                               size_t words = max_uintx);
 764 
 765   inline ParCompactionManager* compaction_manager() const;
 766   inline ParMarkBitMap*        bitmap() const;
 767   inline size_t                words_remaining() const;
 768   inline bool                  is_full() const;
 769   inline HeapWord*             source() const;
 770 
 771   inline void                  set_source(HeapWord* addr);
 772 
 773   virtual IterationStatus do_addr(HeapWord* addr, size_t words) = 0;
 774 
 775  protected:
 776   inline void decrement_words_remaining(size_t words);
 777 
 778  private:
 779   ParMarkBitMap* const        _bitmap;
 780   ParCompactionManager* const _compaction_manager;
 781   DEBUG_ONLY(const size_t     _initial_words_remaining;) // Useful in debugger.
 782   size_t                      _words_remaining; // Words left to copy.
 783 
 784  protected:
 785   HeapWord*                   _source;          // Next addr that would be read.
 786 };
 787 
 788 inline
 789 ParMarkBitMapClosure::ParMarkBitMapClosure(ParMarkBitMap* bitmap,
 790                                            ParCompactionManager* cm,
 791                                            size_t words):
 792   _bitmap(bitmap), _compaction_manager(cm)
 793 #ifdef  ASSERT
 794   , _initial_words_remaining(words)
 795 #endif
 796 {
 797   _words_remaining = words;
 798   _source = NULL;
 799 }
 800 
 801 inline ParCompactionManager* ParMarkBitMapClosure::compaction_manager() const {
 802   return _compaction_manager;
 803 }
 804 
 805 inline ParMarkBitMap* ParMarkBitMapClosure::bitmap() const {
 806   return _bitmap;
 807 }
 808 
 809 inline size_t ParMarkBitMapClosure::words_remaining() const {
 810   return _words_remaining;
 811 }
 812 
 813 inline bool ParMarkBitMapClosure::is_full() const {
 814   return words_remaining() == 0;
 815 }
 816 
 817 inline HeapWord* ParMarkBitMapClosure::source() const {
 818   return _source;
 819 }
 820 
 821 inline void ParMarkBitMapClosure::set_source(HeapWord* addr) {
 822   _source = addr;
 823 }
 824 
 825 inline void ParMarkBitMapClosure::decrement_words_remaining(size_t words) {
 826   assert(_words_remaining >= words, "processed too many words");
 827   _words_remaining -= words;
 828 }
 829 
 830 // The UseParallelOldGC collector is a stop-the-world garbage collector that
 831 // does parts of the collection using parallel threads.  The collection includes
 832 // the tenured generation and the young generation.  The permanent generation is
 833 // collected at the same time as the other two generations but the permanent
 834 // generation is collect by a single GC thread.  The permanent generation is
 835 // collected serially because of the requirement that during the processing of a
 836 // klass AAA, any objects reference by AAA must already have been processed.
 837 // This requirement is enforced by a left (lower address) to right (higher
 838 // address) sliding compaction.
 839 //
 840 // There are four phases of the collection.
 841 //
 842 //      - marking phase
 843 //      - summary phase
 844 //      - compacting phase
 845 //      - clean up phase
 846 //
 847 // Roughly speaking these phases correspond, respectively, to
 848 //      - mark all the live objects
 849 //      - calculate the destination of each object at the end of the collection
 850 //      - move the objects to their destination
 851 //      - update some references and reinitialize some variables
 852 //
 853 // These three phases are invoked in PSParallelCompact::invoke_no_policy().  The
 854 // marking phase is implemented in PSParallelCompact::marking_phase() and does a
 855 // complete marking of the heap.  The summary phase is implemented in
 856 // PSParallelCompact::summary_phase().  The move and update phase is implemented
 857 // in PSParallelCompact::compact().
 858 //
 859 // A space that is being collected is divided into regions and with each region
 860 // is associated an object of type ParallelCompactData.  Each region is of a
 861 // fixed size and typically will contain more than 1 object and may have parts
 862 // of objects at the front and back of the region.
 863 //
 864 // region            -----+---------------------+----------
 865 // objects covered   [ AAA  )[ BBB )[ CCC   )[ DDD     )
 866 //
 867 // The marking phase does a complete marking of all live objects in the heap.
 868 // The marking also compiles the size of the data for all live objects covered
 869 // by the region.  This size includes the part of any live object spanning onto
 870 // the region (part of AAA if it is live) from the front, all live objects
 871 // contained in the region (BBB and/or CCC if they are live), and the part of
 872 // any live objects covered by the region that extends off the region (part of
 873 // DDD if it is live).  The marking phase uses multiple GC threads and marking
 874 // is done in a bit array of type ParMarkBitMap.  The marking of the bit map is
 875 // done atomically as is the accumulation of the size of the live objects
 876 // covered by a region.
 877 //
 878 // The summary phase calculates the total live data to the left of each region
 879 // XXX.  Based on that total and the bottom of the space, it can calculate the
 880 // starting location of the live data in XXX.  The summary phase calculates for
 881 // each region XXX quantities such as
 882 //
 883 //      - the amount of live data at the beginning of a region from an object
 884 //        entering the region.
 885 //      - the location of the first live data on the region
 886 //      - a count of the number of regions receiving live data from XXX.
 887 //
 888 // See ParallelCompactData for precise details.  The summary phase also
 889 // calculates the dense prefix for the compaction.  The dense prefix is a
 890 // portion at the beginning of the space that is not moved.  The objects in the
 891 // dense prefix do need to have their object references updated.  See method
 892 // summarize_dense_prefix().
 893 //
 894 // The summary phase is done using 1 GC thread.
 895 //
 896 // The compaction phase moves objects to their new location and updates all
 897 // references in the object.
 898 //
 899 // A current exception is that objects that cross a region boundary are moved
 900 // but do not have their references updated.  References are not updated because
 901 // it cannot easily be determined if the klass pointer KKK for the object AAA
 902 // has been updated.  KKK likely resides in a region to the left of the region
 903 // containing AAA.  These AAA's have there references updated at the end in a
 904 // clean up phase.  See the method PSParallelCompact::update_deferred_objects().
 905 // An alternate strategy is being investigated for this deferral of updating.
 906 //
 907 // Compaction is done on a region basis.  A region that is ready to be filled is
 908 // put on a ready list and GC threads take region off the list and fill them.  A
 909 // region is ready to be filled if it empty of live objects.  Such a region may
 910 // have been initially empty (only contained dead objects) or may have had all
 911 // its live objects copied out already.  A region that compacts into itself is
 912 // also ready for filling.  The ready list is initially filled with empty
 913 // regions and regions compacting into themselves.  There is always at least 1
 914 // region that can be put on the ready list.  The regions are atomically added
 915 // and removed from the ready list.
 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  public:
 930   // Inline closure decls
 931   //
 932   class IsAliveClosure: public BoolObjectClosure {
 933    public:
 934     virtual bool do_object_b(oop p);
 935   };
 936 
 937   class AdjustPointerClosure: public ExtendedOopClosure {
 938    public:
 939     AdjustPointerClosure(ParCompactionManager* cm) {
 940       assert(cm != NULL, "associate ParCompactionManage should not be NULL");
 941       _cm = cm;
 942     }
 943     template <typename T> void do_oop_nv(T* p);
 944     virtual void do_oop(oop* p);
 945     virtual void do_oop(narrowOop* p);
 946 
 947     // This closure provides its own oop verification code.
 948     debug_only(virtual bool should_verify_oops() { return false; })
 949    private:
 950     ParCompactionManager* _cm;
 951   };
 952 
 953   class AdjustKlassClosure : public KlassClosure {
 954    public:
 955     AdjustKlassClosure(ParCompactionManager* cm) {
 956       assert(cm != NULL, "associate ParCompactionManage should not be NULL");
 957       _cm = cm;
 958     }
 959     void do_klass(Klass* klass);
 960    private:
 961     ParCompactionManager* _cm;
 962   };
 963 
 964   friend class AdjustPointerClosure;
 965   friend class AdjustKlassClosure;
 966   friend class RefProcTaskProxy;
 967   friend class PSParallelCompactTest;
 968 
 969  private:
 970   static STWGCTimer           _gc_timer;
 971   static ParallelOldTracer    _gc_tracer;
 972   static elapsedTimer         _accumulated_time;
 973   static unsigned int         _total_invocations;
 974   static unsigned int         _maximum_compaction_gc_num;
 975   static jlong                _time_of_last_gc;   // ms
 976   static CollectorCounters*   _counters;
 977   static ParMarkBitMap        _mark_bitmap;
 978   static ParallelCompactData  _summary_data;
 979   static IsAliveClosure       _is_alive_closure;
 980   static SpaceInfo            _space_info[last_space_id];
 981 
 982   // Reference processing (used in ...follow_contents)
 983   static ReferenceProcessor*  _ref_processor;
 984 
 985   // Values computed at initialization and used by dead_wood_limiter().
 986   static double _dwl_mean;
 987   static double _dwl_std_dev;
 988   static double _dwl_first_term;
 989   static double _dwl_adjustment;
 990 #ifdef  ASSERT
 991   static bool   _dwl_initialized;
 992 #endif  // #ifdef ASSERT
 993 
 994  public:
 995   static ParallelOldTracer* gc_tracer() { return &_gc_tracer; }
 996 
 997  private:
 998 
 999   static void initialize_space_info();
1000 
1001   // Clear the marking bitmap and summary data that cover the specified space.
1002   static void clear_data_covering_space(SpaceId id);
1003 
1004   static void pre_compact();
1005   static void post_compact();
1006 
1007   // Mark live objects
1008   static void marking_phase(ParCompactionManager* cm,
1009                             bool maximum_heap_compaction,
1010                             ParallelOldTracer *gc_tracer);
1011 
1012   // Compute the dense prefix for the designated space.  This is an experimental
1013   // implementation currently not used in production.
1014   static HeapWord* compute_dense_prefix_via_density(const SpaceId id,
1015                                                     bool maximum_compaction);
1016 
1017   // Methods used to compute the dense prefix.
1018 
1019   // Compute the value of the normal distribution at x = density.  The mean and
1020   // standard deviation are values saved by initialize_dead_wood_limiter().
1021   static inline double normal_distribution(double density);
1022 
1023   // Initialize the static vars used by dead_wood_limiter().
1024   static void initialize_dead_wood_limiter();
1025 
1026   // Return the percentage of space that can be treated as "dead wood" (i.e.,
1027   // not reclaimed).
1028   static double dead_wood_limiter(double density, size_t min_percent);
1029 
1030   // Find the first (left-most) region in the range [beg, end) that has at least
1031   // dead_words of dead space to the left.  The argument beg must be the first
1032   // region in the space that is not completely live.
1033   static RegionData* dead_wood_limit_region(const RegionData* beg,
1034                                             const RegionData* end,
1035                                             size_t dead_words);
1036 
1037   // Return a pointer to the first region in the range [beg, end) that is not
1038   // completely full.
1039   static RegionData* first_dead_space_region(const RegionData* beg,
1040                                              const RegionData* end);
1041 
1042   // Return a value indicating the benefit or 'yield' if the compacted region
1043   // were to start (or equivalently if the dense prefix were to end) at the
1044   // candidate region.  Higher values are better.
1045   //
1046   // The value is based on the amount of space reclaimed vs. the costs of (a)
1047   // updating references in the dense prefix plus (b) copying objects and
1048   // updating references in the compacted region.
1049   static inline double reclaimed_ratio(const RegionData* const candidate,
1050                                        HeapWord* const bottom,
1051                                        HeapWord* const top,
1052                                        HeapWord* const new_top);
1053 
1054   // Compute the dense prefix for the designated space.
1055   static HeapWord* compute_dense_prefix(const SpaceId id,
1056                                         bool maximum_compaction);
1057 
1058   // Return true if dead space crosses onto the specified Region; bit must be
1059   // the bit index corresponding to the first word of the Region.
1060   static inline bool dead_space_crosses_boundary(const RegionData* region,
1061                                                  idx_t bit);
1062 
1063   // Summary phase utility routine to fill dead space (if any) at the dense
1064   // prefix boundary.  Should only be called if the the dense prefix is
1065   // non-empty.
1066   static void fill_dense_prefix_end(SpaceId id);
1067 
1068   static void summarize_spaces_quick();
1069   static void summarize_space(SpaceId id, bool maximum_compaction);
1070   static void summary_phase(ParCompactionManager* cm, bool maximum_compaction);
1071 
1072   // Adjust addresses in roots.  Does not adjust addresses in heap.
1073   static void adjust_roots(ParCompactionManager* cm);
1074 
1075   DEBUG_ONLY(static void write_block_fill_histogram();)
1076 
1077   // Move objects to new locations.
1078   static void compact_perm(ParCompactionManager* cm);
1079   static void compact();
1080 
1081   // Add available regions to the stack and draining tasks to the task queue.
1082   static void prepare_region_draining_tasks(GCTaskQueue* q,
1083                                             uint parallel_gc_threads);
1084 
1085   // Add dense prefix update tasks to the task queue.
1086   static void enqueue_dense_prefix_tasks(GCTaskQueue* q,
1087                                          uint parallel_gc_threads);
1088 
1089   // Add region stealing tasks to the task queue.
1090   static void enqueue_region_stealing_tasks(
1091                                        GCTaskQueue* q,
1092                                        ParallelTaskTerminator* terminator_ptr,
1093                                        uint parallel_gc_threads);
1094 
1095   // If objects are left in eden after a collection, try to move the boundary
1096   // and absorb them into the old gen.  Returns true if eden was emptied.
1097   static bool absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
1098                                          PSYoungGen* young_gen,
1099                                          PSOldGen* old_gen);
1100 
1101   // Reset time since last full gc
1102   static void reset_millis_since_last_gc();
1103 
1104 #ifndef PRODUCT
1105   // Print generic summary data
1106   static void print_generic_summary_data(ParallelCompactData& summary_data,
1107                                          HeapWord* const beg_addr,
1108                                          HeapWord* const end_addr);
1109 #endif  // #ifndef PRODUCT
1110 
1111  public:
1112 
1113   PSParallelCompact();
1114 
1115   static void invoke(bool maximum_heap_compaction);
1116   static bool invoke_no_policy(bool maximum_heap_compaction);
1117 
1118   static void post_initialize();
1119   // Perform initialization for PSParallelCompact that requires
1120   // allocations.  This should be called during the VM initialization
1121   // at a pointer where it would be appropriate to return a JNI_ENOMEM
1122   // in the event of a failure.
1123   static bool initialize();
1124 
1125   // Closure accessors
1126   static BoolObjectClosure* is_alive_closure()     { return (BoolObjectClosure*)&_is_alive_closure; }
1127 
1128   // Public accessors
1129   static elapsedTimer* accumulated_time() { return &_accumulated_time; }
1130   static unsigned int total_invocations() { return _total_invocations; }
1131   static CollectorCounters* counters()    { return _counters; }
1132 
1133   // Used to add tasks
1134   static GCTaskManager* const gc_task_manager();
1135 
1136   // Marking support
1137   static inline bool mark_obj(oop obj);
1138   static inline bool is_marked(oop obj);
1139 
1140   template <class T> static inline void adjust_pointer(T* p, ParCompactionManager* cm);
1141 
1142   // Compaction support.
1143   // Return true if p is in the range [beg_addr, end_addr).
1144   static inline bool is_in(HeapWord* p, HeapWord* beg_addr, HeapWord* end_addr);
1145   static inline bool is_in(oop* p, HeapWord* beg_addr, HeapWord* end_addr);
1146 
1147   // Convenience wrappers for per-space data kept in _space_info.
1148   static inline MutableSpace*     space(SpaceId space_id);
1149   static inline HeapWord*         new_top(SpaceId space_id);
1150   static inline HeapWord*         dense_prefix(SpaceId space_id);
1151   static inline ObjectStartArray* start_array(SpaceId space_id);
1152 
1153   // Move and update the live objects in the specified space.
1154   static void move_and_update(ParCompactionManager* cm, SpaceId space_id);
1155 
1156   // Process the end of the given region range in the dense prefix.
1157   // This includes saving any object not updated.
1158   static void dense_prefix_regions_epilogue(ParCompactionManager* cm,
1159                                             size_t region_start_index,
1160                                             size_t region_end_index,
1161                                             idx_t exiting_object_offset,
1162                                             idx_t region_offset_start,
1163                                             idx_t region_offset_end);
1164 
1165   // Update a region in the dense prefix.  For each live object
1166   // in the region, update it's interior references.  For each
1167   // dead object, fill it with deadwood. Dead space at the end
1168   // of a region range will be filled to the start of the next
1169   // live object regardless of the region_index_end.  None of the
1170   // objects in the dense prefix move and dead space is dead
1171   // (holds only dead objects that don't need any processing), so
1172   // dead space can be filled in any order.
1173   static void update_and_deadwood_in_dense_prefix(ParCompactionManager* cm,
1174                                                   SpaceId space_id,
1175                                                   size_t region_index_start,
1176                                                   size_t region_index_end);
1177 
1178   // Return the address of the count + 1st live word in the range [beg, end).
1179   static HeapWord* skip_live_words(HeapWord* beg, HeapWord* end, size_t count);
1180 
1181   // Return the address of the word to be copied to dest_addr, which must be
1182   // aligned to a region boundary.
1183   static HeapWord* first_src_addr(HeapWord* const dest_addr,
1184                                   SpaceId src_space_id,
1185                                   size_t src_region_idx);
1186 
1187   // Determine the next source region, set closure.source() to the start of the
1188   // new region return the region index.  Parameter end_addr is the address one
1189   // beyond the end of source range just processed.  If necessary, switch to a
1190   // new source space and set src_space_id (in-out parameter) and src_space_top
1191   // (out parameter) accordingly.
1192   static size_t next_src_region(MoveAndUpdateClosure& closure,
1193                                 SpaceId& src_space_id,
1194                                 HeapWord*& src_space_top,
1195                                 HeapWord* end_addr);
1196 
1197   // Decrement the destination count for each non-empty source region in the
1198   // range [beg_region, region(region_align_up(end_addr))).  If the destination
1199   // count for a region goes to 0 and it needs to be filled, enqueue it.
1200   static void decrement_destination_counts(ParCompactionManager* cm,
1201                                            SpaceId src_space_id,
1202                                            size_t beg_region,
1203                                            HeapWord* end_addr);
1204 
1205   // Fill a region, copying objects from one or more source regions.
1206   static void fill_region(ParCompactionManager* cm, size_t region_idx);
1207   static void fill_and_update_region(ParCompactionManager* cm, size_t region) {
1208     fill_region(cm, region);
1209   }
1210 
1211   // Fill in the block table for the specified region.
1212   static void fill_blocks(size_t region_idx);
1213 
1214   // Update the deferred objects in the space.
1215   static void update_deferred_objects(ParCompactionManager* cm, SpaceId id);
1216 
1217   static ParMarkBitMap* mark_bitmap() { return &_mark_bitmap; }
1218   static ParallelCompactData& summary_data() { return _summary_data; }
1219 
1220   // Reference Processing
1221   static ReferenceProcessor* const ref_processor() { return _ref_processor; }
1222 
1223   static STWGCTimer* gc_timer() { return &_gc_timer; }
1224 
1225   // Return the SpaceId for the given address.
1226   static SpaceId space_id(HeapWord* addr);
1227 
1228   // Time since last full gc (in milliseconds).
1229   static jlong millis_since_last_gc();
1230 
1231   static void print_on_error(outputStream* st);
1232 
1233 #ifndef PRODUCT
1234   // Debugging support.
1235   static const char* space_names[last_space_id];
1236   static void print_region_ranges();
1237   static void print_dense_prefix_stats(const char* const algorithm,
1238                                        const SpaceId id,
1239                                        const bool maximum_compaction,
1240                                        HeapWord* const addr);
1241   static void summary_phase_msg(SpaceId dst_space_id,
1242                                 HeapWord* dst_beg, HeapWord* dst_end,
1243                                 SpaceId src_space_id,
1244                                 HeapWord* src_beg, HeapWord* src_end);
1245 #endif  // #ifndef PRODUCT
1246 
1247 #ifdef  ASSERT
1248   // Sanity check the new location of a word in the heap.
1249   static inline void check_new_location(HeapWord* old_addr, HeapWord* new_addr);
1250   // Verify that all the regions have been emptied.
1251   static void verify_complete(SpaceId space_id);
1252 #endif  // #ifdef ASSERT
1253 };
1254 
1255 class MoveAndUpdateClosure: public ParMarkBitMapClosure {
1256  public:
1257   inline MoveAndUpdateClosure(ParMarkBitMap* bitmap, ParCompactionManager* cm,
1258                               ObjectStartArray* start_array,
1259                               HeapWord* destination, size_t words);
1260 
1261   // Accessors.
1262   HeapWord* destination() const         { return _destination; }
1263 
1264   // If the object will fit (size <= words_remaining()), copy it to the current
1265   // destination, update the interior oops and the start array and return either
1266   // full (if the closure is full) or incomplete.  If the object will not fit,
1267   // return would_overflow.
1268   virtual IterationStatus do_addr(HeapWord* addr, size_t size);
1269 
1270   // Copy enough words to fill this closure, starting at source().  Interior
1271   // oops and the start array are not updated.  Return full.
1272   IterationStatus copy_until_full();
1273 
1274   // Copy enough words to fill this closure or to the end of an object,
1275   // whichever is smaller, starting at source().  Interior oops and the start
1276   // array are not updated.
1277   void copy_partial_obj();
1278 
1279  protected:
1280   // Update variables to indicate that word_count words were processed.
1281   inline void update_state(size_t word_count);
1282 
1283  protected:
1284   ObjectStartArray* const _start_array;
1285   HeapWord*               _destination;         // Next addr to be written.
1286 };
1287 
1288 inline
1289 MoveAndUpdateClosure::MoveAndUpdateClosure(ParMarkBitMap* bitmap,
1290                                            ParCompactionManager* cm,
1291                                            ObjectStartArray* start_array,
1292                                            HeapWord* destination,
1293                                            size_t words) :
1294   ParMarkBitMapClosure(bitmap, cm, words), _start_array(start_array)
1295 {
1296   _destination = destination;
1297 }
1298 
1299 inline void MoveAndUpdateClosure::update_state(size_t words)
1300 {
1301   decrement_words_remaining(words);
1302   _source += words;
1303   _destination += words;
1304 }
1305 
1306 class UpdateOnlyClosure: public ParMarkBitMapClosure {
1307  private:
1308   const PSParallelCompact::SpaceId _space_id;
1309   ObjectStartArray* const          _start_array;
1310 
1311  public:
1312   UpdateOnlyClosure(ParMarkBitMap* mbm,
1313                     ParCompactionManager* cm,
1314                     PSParallelCompact::SpaceId space_id);
1315 
1316   // Update the object.
1317   virtual IterationStatus do_addr(HeapWord* addr, size_t words);
1318 
1319   inline void do_addr(HeapWord* addr);
1320 };
1321 
1322 class FillClosure: public ParMarkBitMapClosure {
1323  public:
1324   FillClosure(ParCompactionManager* cm, PSParallelCompact::SpaceId space_id);
1325 
1326   virtual IterationStatus do_addr(HeapWord* addr, size_t size);
1327 
1328  private:
1329   ObjectStartArray* const _start_array;
1330 };
1331 
1332 #endif // SHARE_VM_GC_PARALLEL_PSPARALLELCOMPACT_HPP