1 /*
   2  * Copyright (c) 2005, 2012, 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
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  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_IMPLEMENTATION_PARALLELSCAVENGE_PSPARALLELCOMPACT_HPP
  26 #define SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_PSPARALLELCOMPACT_HPP
  27 
  28 #include "gc_implementation/parallelScavenge/objectStartArray.hpp"
  29 #include "gc_implementation/parallelScavenge/parMarkBitMap.hpp"
  30 #include "gc_implementation/parallelScavenge/psCompactionManager.hpp"
  31 #include "gc_implementation/shared/collectorCounters.hpp"
  32 #include "gc_implementation/shared/markSweep.hpp"
  33 #include "gc_implementation/shared/mutableSpace.hpp"
  34 #include "memory/sharedHeap.hpp"
  35 #include "oops/oop.hpp"
  36 
  37 class ParallelScavengeHeap;
  38 class PSAdaptiveSizePolicy;
  39 class PSYoungGen;
  40 class PSOldGen;
  41 class PSPermGen;
  42 class ParCompactionManager;
  43 class ParallelTaskTerminator;
  44 class PSParallelCompact;
  45 class GCTaskManager;
  46 class GCTaskQueue;
  47 class PreGCValues;
  48 class MoveAndUpdateClosure;
  49 class RefProcTaskExecutor;
  50 class ParallelOldTracer;
  51 class STWGCTimer;
  52 
  53 // The SplitInfo class holds the information needed to 'split' a source region
  54 // so that the live data can be copied to two destination *spaces*.  Normally,
  55 // all the live data in a region is copied to a single destination space (e.g.,
  56 // everything live in a region in eden is copied entirely into the old gen).
  57 // However, when the heap is nearly full, all the live data in eden may not fit
  58 // into the old gen.  Copying only some of the regions from eden to old gen
  59 // requires finding a region that does not contain a partial object (i.e., no
  60 // live object crosses the region boundary) somewhere near the last object that
  61 // does fit into the old gen.  Since it's not always possible to find such a
  62 // region, splitting is necessary for predictable behavior.
  63 //
  64 // A region is always split at the end of the partial object.  This avoids
  65 // additional tests when calculating the new location of a pointer, which is a
  66 // very hot code path.  The partial object and everything to its left will be
  67 // copied to another space (call it dest_space_1).  The live data to the right
  68 // of the partial object will be copied either within the space itself, or to a
  69 // different destination space (distinct from dest_space_1).
  70 //
  71 // Split points are identified during the summary phase, when region
  72 // destinations are computed:  data about the split, including the
  73 // partial_object_size, is recorded in a SplitInfo record and the
  74 // partial_object_size field in the summary data is set to zero.  The zeroing is
  75 // possible (and necessary) since the partial object will move to a different
  76 // destination space than anything to its right, thus the partial object should
  77 // not affect the locations of any objects to its right.
  78 //
  79 // The recorded data is used during the compaction phase, but only rarely:  when
  80 // the partial object on the split region will be copied across a destination
  81 // region boundary.  This test is made once each time a region is filled, and is
  82 // a simple address comparison, so the overhead is negligible (see
  83 // PSParallelCompact::first_src_addr()).
  84 //
  85 // Notes:
  86 //
  87 // Only regions with partial objects are split; a region without a partial
  88 // object does not need any extra bookkeeping.
  89 //
  90 // At most one region is split per space, so the amount of data required is
  91 // constant.
  92 //
  93 // A region is split only when the destination space would overflow.  Once that
  94 // happens, the destination space is abandoned and no other data (even from
  95 // other source spaces) is targeted to that destination space.  Abandoning the
  96 // destination space may leave a somewhat large unused area at the end, if a
  97 // large object caused the overflow.
  98 //
  99 // Future work:
 100 //
 101 // More bookkeeping would be required to continue to use the destination space.
 102 // The most general solution would allow data from regions in two different
 103 // source spaces to be "joined" in a single destination region.  At the very
 104 // least, additional code would be required in next_src_region() to detect the
 105 // join and skip to an out-of-order source region.  If the join region was also
 106 // the last destination region to which a split region was copied (the most
 107 // likely case), then additional work would be needed to get fill_region() to
 108 // stop iteration and switch to a new source region at the right point.  Basic
 109 // idea would be to use a fake value for the top of the source space.  It is
 110 // doable, if a bit tricky.
 111 //
 112 // A simpler (but less general) solution would fill the remainder of the
 113 // destination region with a dummy object and continue filling the next
 114 // destination region.
 115 
 116 class SplitInfo
 117 {
 118 public:
 119   // Return true if this split info is valid (i.e., if a split has been
 120   // recorded).  The very first region cannot have a partial object and thus is
 121   // never split, so 0 is the 'invalid' value.
 122   bool is_valid() const { return _src_region_idx > 0; }
 123 
 124   // Return true if this split holds data for the specified source region.
 125   inline bool is_split(size_t source_region) const;
 126 
 127   // The index of the split region, the size of the partial object on that
 128   // region and the destination of the partial object.
 129   size_t    src_region_idx() const   { return _src_region_idx; }
 130   size_t    partial_obj_size() const { return _partial_obj_size; }
 131   HeapWord* destination() const      { return _destination; }
 132 
 133   // The destination count of the partial object referenced by this split
 134   // (either 1 or 2).  This must be added to the destination count of the
 135   // remainder of the source region.
 136   unsigned int destination_count() const { return _destination_count; }
 137 
 138   // If a word within the partial object will be written to the first word of a
 139   // destination region, this is the address of the destination region;
 140   // otherwise this is NULL.
 141   HeapWord* dest_region_addr() const     { return _dest_region_addr; }
 142 
 143   // If a word within the partial object will be written to the first word of a
 144   // destination region, this is the address of that word within the partial
 145   // object; otherwise this is NULL.
 146   HeapWord* first_src_addr() const       { return _first_src_addr; }
 147 
 148   // Record the data necessary to split the region src_region_idx.
 149   void record(size_t src_region_idx, size_t partial_obj_size,
 150               HeapWord* destination);
 151 
 152   void clear();
 153 
 154   DEBUG_ONLY(void verify_clear();)
 155 
 156 private:
 157   size_t       _src_region_idx;
 158   size_t       _partial_obj_size;
 159   HeapWord*    _destination;
 160   unsigned int _destination_count;
 161   HeapWord*    _dest_region_addr;
 162   HeapWord*    _first_src_addr;
 163 };
 164 
 165 inline bool SplitInfo::is_split(size_t region_idx) const
 166 {
 167   return _src_region_idx == region_idx && is_valid();
 168 }
 169 
 170 class SpaceInfo
 171 {
 172  public:
 173   MutableSpace* space() const { return _space; }
 174 
 175   // Where the free space will start after the collection.  Valid only after the
 176   // summary phase completes.
 177   HeapWord* new_top() const { return _new_top; }
 178 
 179   // Allows new_top to be set.
 180   HeapWord** new_top_addr() { return &_new_top; }
 181 
 182   // Where the smallest allowable dense prefix ends (used only for perm gen).
 183   HeapWord* min_dense_prefix() const { return _min_dense_prefix; }
 184 
 185   // Where the dense prefix ends, or the compacted region begins.
 186   HeapWord* dense_prefix() const { return _dense_prefix; }
 187 
 188   // The start array for the (generation containing the) space, or NULL if there
 189   // is no start array.
 190   ObjectStartArray* start_array() const { return _start_array; }
 191 
 192   SplitInfo& split_info() { return _split_info; }
 193 
 194   void set_space(MutableSpace* s)           { _space = s; }
 195   void set_new_top(HeapWord* addr)          { _new_top = addr; }
 196   void set_min_dense_prefix(HeapWord* addr) { _min_dense_prefix = addr; }
 197   void set_dense_prefix(HeapWord* addr)     { _dense_prefix = addr; }
 198   void set_start_array(ObjectStartArray* s) { _start_array = s; }
 199 
 200   void publish_new_top() const              { _space->set_top(_new_top); }
 201 
 202  private:
 203   MutableSpace*     _space;
 204   HeapWord*         _new_top;
 205   HeapWord*         _min_dense_prefix;
 206   HeapWord*         _dense_prefix;
 207   ObjectStartArray* _start_array;
 208   SplitInfo         _split_info;
 209 };
 210 
 211 class ParallelCompactData
 212 {
 213 public:
 214   // Sizes are in HeapWords, unless indicated otherwise.
 215   static const size_t Log2RegionSize;
 216   static const size_t RegionSize;
 217   static const size_t RegionSizeBytes;
 218 
 219   // Mask for the bits in a size_t to get an offset within a region.
 220   static const size_t RegionSizeOffsetMask;
 221   // Mask for the bits in a pointer to get an offset within a region.
 222   static const size_t RegionAddrOffsetMask;
 223   // Mask for the bits in a pointer to get the address of the start of a region.
 224   static const size_t RegionAddrMask;
 225 
 226   class RegionData
 227   {
 228   public:
 229     // Destination address of the region.
 230     HeapWord* destination() const { return _destination; }
 231 
 232     // The first region containing data destined for this region.
 233     size_t source_region() const { return _source_region; }
 234 
 235     // The object (if any) starting in this region and ending in a different
 236     // region that could not be updated during the main (parallel) compaction
 237     // phase.  This is different from _partial_obj_addr, which is an object that
 238     // extends onto a source region.  However, the two uses do not overlap in
 239     // time, so the same field is used to save space.
 240     HeapWord* deferred_obj_addr() const { return _partial_obj_addr; }
 241 
 242     // The starting address of the partial object extending onto the region.
 243     HeapWord* partial_obj_addr() const { return _partial_obj_addr; }
 244 
 245     // Size of the partial object extending onto the region (words).
 246     size_t partial_obj_size() const { return _partial_obj_size; }
 247 
 248     // Size of live data that lies within this region due to objects that start
 249     // in this region (words).  This does not include the partial object
 250     // extending onto the region (if any), or the part of an object that extends
 251     // onto the next region (if any).
 252     size_t live_obj_size() const { return _dc_and_los & los_mask; }
 253 
 254     // Total live data that lies within the region (words).
 255     size_t data_size() const { return partial_obj_size() + live_obj_size(); }
 256 
 257     // The destination_count is the number of other regions to which data from
 258     // this region will be copied.  At the end of the summary phase, the valid
 259     // values of destination_count are
 260     //
 261     // 0 - data from the region will be compacted completely into itself, or the
 262     //     region is empty.  The region can be claimed and then filled.
 263     // 1 - data from the region will be compacted into 1 other region; some
 264     //     data from the region may also be compacted into the region itself.
 265     // 2 - data from the region will be copied to 2 other regions.
 266     //
 267     // During compaction as regions are emptied, the destination_count is
 268     // decremented (atomically) and when it reaches 0, it can be claimed and
 269     // then filled.
 270     //
 271     // A region is claimed for processing by atomically changing the
 272     // destination_count to the claimed value (dc_claimed).  After a region has
 273     // been filled, the destination_count should be set to the completed value
 274     // (dc_completed).
 275     inline uint destination_count() const;
 276     inline uint destination_count_raw() const;
 277 
 278     // The location of the java heap data that corresponds to this region.
 279     inline HeapWord* data_location() const;
 280 
 281     // The highest address referenced by objects in this region.
 282     inline HeapWord* highest_ref() const;
 283 
 284     // Whether this region is available to be claimed, has been claimed, or has
 285     // been completed.
 286     //
 287     // Minor subtlety:  claimed() returns true if the region is marked
 288     // completed(), which is desirable since a region must be claimed before it
 289     // can be completed.
 290     bool available() const { return _dc_and_los < dc_one; }
 291     bool claimed() const   { return _dc_and_los >= dc_claimed; }
 292     bool completed() const { return _dc_and_los >= dc_completed; }
 293 
 294     // These are not atomic.
 295     void set_destination(HeapWord* addr)       { _destination = addr; }
 296     void set_source_region(size_t region)      { _source_region = region; }
 297     void set_deferred_obj_addr(HeapWord* addr) { _partial_obj_addr = addr; }
 298     void set_partial_obj_addr(HeapWord* addr)  { _partial_obj_addr = addr; }
 299     void set_partial_obj_size(size_t words)    {
 300       _partial_obj_size = (region_sz_t) words;
 301     }
 302 
 303     inline void set_destination_count(uint count);
 304     inline void set_live_obj_size(size_t words);
 305     inline void set_data_location(HeapWord* addr);
 306     inline void set_completed();
 307     inline bool claim_unsafe();
 308 
 309     // These are atomic.
 310     inline void add_live_obj(size_t words);
 311     inline void set_highest_ref(HeapWord* addr);
 312     inline void decrement_destination_count();
 313     inline bool claim();
 314 
 315   private:
 316     // The type used to represent object sizes within a region.
 317     typedef uint region_sz_t;
 318 
 319     // Constants for manipulating the _dc_and_los field, which holds both the
 320     // destination count and live obj size.  The live obj size lives at the
 321     // least significant end so no masking is necessary when adding.
 322     static const region_sz_t dc_shift;           // Shift amount.
 323     static const region_sz_t dc_mask;            // Mask for destination count.
 324     static const region_sz_t dc_one;             // 1, shifted appropriately.
 325     static const region_sz_t dc_claimed;         // Region has been claimed.
 326     static const region_sz_t dc_completed;       // Region has been completed.
 327     static const region_sz_t los_mask;           // Mask for live obj size.
 328 
 329     HeapWord*            _destination;
 330     size_t               _source_region;
 331     HeapWord*            _partial_obj_addr;
 332     region_sz_t          _partial_obj_size;
 333     region_sz_t volatile _dc_and_los;
 334 #ifdef ASSERT
 335     // These enable optimizations that are only partially implemented.  Use
 336     // debug builds to prevent the code fragments from breaking.
 337     HeapWord*            _data_location;
 338     HeapWord*            _highest_ref;
 339 #endif  // #ifdef ASSERT
 340 
 341 #ifdef ASSERT
 342    public:
 343     uint            _pushed;   // 0 until region is pushed onto a worker's stack
 344    private:
 345 #endif
 346   };
 347 
 348 public:
 349   ParallelCompactData();
 350   bool initialize(MemRegion covered_region);
 351 
 352   size_t region_count() const { return _region_count; }
 353 
 354   // Convert region indices to/from RegionData pointers.
 355   inline RegionData* region(size_t region_idx) const;
 356   inline size_t     region(const RegionData* const region_ptr) const;
 357 
 358   // Returns true if the given address is contained within the region
 359   bool region_contains(size_t region_index, HeapWord* addr);
 360 
 361   void add_obj(HeapWord* addr, size_t len);
 362   void add_obj(oop p, size_t len) { add_obj((HeapWord*)p, len); }
 363 
 364   // Fill in the regions covering [beg, end) so that no data moves; i.e., the
 365   // destination of region n is simply the start of region n.  The argument beg
 366   // must be region-aligned; end need not be.
 367   void summarize_dense_prefix(HeapWord* beg, HeapWord* end);
 368 
 369   HeapWord* summarize_split_space(size_t src_region, SplitInfo& split_info,
 370                                   HeapWord* destination, HeapWord* target_end,
 371                                   HeapWord** target_next);
 372   bool summarize(SplitInfo& split_info,
 373                  HeapWord* source_beg, HeapWord* source_end,
 374                  HeapWord** source_next,
 375                  HeapWord* target_beg, HeapWord* target_end,
 376                  HeapWord** target_next);
 377 
 378   void clear();
 379   void clear_range(size_t beg_region, size_t end_region);
 380   void clear_range(HeapWord* beg, HeapWord* end) {
 381     clear_range(addr_to_region_idx(beg), addr_to_region_idx(end));
 382   }
 383 
 384   // Return the number of words between addr and the start of the region
 385   // containing addr.
 386   inline size_t     region_offset(const HeapWord* addr) const;
 387 
 388   // Convert addresses to/from a region index or region pointer.
 389   inline size_t     addr_to_region_idx(const HeapWord* addr) const;
 390   inline RegionData* addr_to_region_ptr(const HeapWord* addr) const;
 391   inline HeapWord*  region_to_addr(size_t region) const;
 392   inline HeapWord*  region_to_addr(size_t region, size_t offset) const;
 393   inline HeapWord*  region_to_addr(const RegionData* region) const;
 394 
 395   inline HeapWord*  region_align_down(HeapWord* addr) const;
 396   inline HeapWord*  region_align_up(HeapWord* addr) const;
 397   inline bool       is_region_aligned(HeapWord* addr) const;
 398 
 399   // Return the address one past the end of the partial object.
 400   HeapWord* partial_obj_end(size_t region_idx) const;
 401 
 402   // Return the new location of the object p after the
 403   // the compaction.
 404   HeapWord* calc_new_pointer(HeapWord* addr);
 405 
 406   HeapWord* calc_new_pointer(oop p) {
 407     return calc_new_pointer((HeapWord*) p);
 408   }
 409 
 410   // Return the updated address for the given klass
 411   klassOop calc_new_klass(klassOop);
 412 
 413 #ifdef  ASSERT
 414   void verify_clear(const PSVirtualSpace* vspace);
 415   void verify_clear();
 416 #endif  // #ifdef ASSERT
 417 
 418 private:
 419   bool initialize_region_data(size_t region_size);
 420   PSVirtualSpace* create_vspace(size_t count, size_t element_size);
 421 
 422 private:
 423   HeapWord*       _region_start;
 424 #ifdef  ASSERT
 425   HeapWord*       _region_end;
 426 #endif  // #ifdef ASSERT
 427 
 428   PSVirtualSpace* _region_vspace;
 429   RegionData*     _region_data;
 430   size_t          _region_count;
 431 };
 432 
 433 inline uint
 434 ParallelCompactData::RegionData::destination_count_raw() const
 435 {
 436   return _dc_and_los & dc_mask;
 437 }
 438 
 439 inline uint
 440 ParallelCompactData::RegionData::destination_count() const
 441 {
 442   return destination_count_raw() >> dc_shift;
 443 }
 444 
 445 inline void
 446 ParallelCompactData::RegionData::set_destination_count(uint count)
 447 {
 448   assert(count <= (dc_completed >> dc_shift), "count too large");
 449   const region_sz_t live_sz = (region_sz_t) live_obj_size();
 450   _dc_and_los = (count << dc_shift) | live_sz;
 451 }
 452 
 453 inline void ParallelCompactData::RegionData::set_live_obj_size(size_t words)
 454 {
 455   assert(words <= los_mask, "would overflow");
 456   _dc_and_los = destination_count_raw() | (region_sz_t)words;
 457 }
 458 
 459 inline void ParallelCompactData::RegionData::decrement_destination_count()
 460 {
 461   assert(_dc_and_los < dc_claimed, "already claimed");
 462   assert(_dc_and_los >= dc_one, "count would go negative");
 463   Atomic::add((int)dc_mask, (volatile int*)&_dc_and_los);
 464 }
 465 
 466 inline HeapWord* ParallelCompactData::RegionData::data_location() const
 467 {
 468   DEBUG_ONLY(return _data_location;)
 469   NOT_DEBUG(return NULL;)
 470 }
 471 
 472 inline HeapWord* ParallelCompactData::RegionData::highest_ref() const
 473 {
 474   DEBUG_ONLY(return _highest_ref;)
 475   NOT_DEBUG(return NULL;)
 476 }
 477 
 478 inline void ParallelCompactData::RegionData::set_data_location(HeapWord* addr)
 479 {
 480   DEBUG_ONLY(_data_location = addr;)
 481 }
 482 
 483 inline void ParallelCompactData::RegionData::set_completed()
 484 {
 485   assert(claimed(), "must be claimed first");
 486   _dc_and_los = dc_completed | (region_sz_t) live_obj_size();
 487 }
 488 
 489 // MT-unsafe claiming of a region.  Should only be used during single threaded
 490 // execution.
 491 inline bool ParallelCompactData::RegionData::claim_unsafe()
 492 {
 493   if (available()) {
 494     _dc_and_los |= dc_claimed;
 495     return true;
 496   }
 497   return false;
 498 }
 499 
 500 inline void ParallelCompactData::RegionData::add_live_obj(size_t words)
 501 {
 502   assert(words <= (size_t)los_mask - live_obj_size(), "overflow");
 503   Atomic::add((int) words, (volatile int*) &_dc_and_los);
 504 }
 505 
 506 inline void ParallelCompactData::RegionData::set_highest_ref(HeapWord* addr)
 507 {
 508 #ifdef ASSERT
 509   HeapWord* tmp = _highest_ref;
 510   while (addr > tmp) {
 511     tmp = (HeapWord*)Atomic::cmpxchg_ptr(addr, &_highest_ref, tmp);
 512   }
 513 #endif  // #ifdef ASSERT
 514 }
 515 
 516 inline bool ParallelCompactData::RegionData::claim()
 517 {
 518   const int los = (int) live_obj_size();
 519   const int old = Atomic::cmpxchg(dc_claimed | los,
 520                                   (volatile int*) &_dc_and_los, los);
 521   return old == los;
 522 }
 523 
 524 inline ParallelCompactData::RegionData*
 525 ParallelCompactData::region(size_t region_idx) const
 526 {
 527   assert(region_idx <= region_count(), "bad arg");
 528   return _region_data + region_idx;
 529 }
 530 
 531 inline size_t
 532 ParallelCompactData::region(const RegionData* const region_ptr) const
 533 {
 534   assert(region_ptr >= _region_data, "bad arg");
 535   assert(region_ptr <= _region_data + region_count(), "bad arg");
 536   return pointer_delta(region_ptr, _region_data, sizeof(RegionData));
 537 }
 538 
 539 inline size_t
 540 ParallelCompactData::region_offset(const HeapWord* addr) const
 541 {
 542   assert(addr >= _region_start, "bad addr");
 543   assert(addr <= _region_end, "bad addr");
 544   return (size_t(addr) & RegionAddrOffsetMask) >> LogHeapWordSize;
 545 }
 546 
 547 inline size_t
 548 ParallelCompactData::addr_to_region_idx(const HeapWord* addr) const
 549 {
 550   assert(addr >= _region_start, "bad addr");
 551   assert(addr <= _region_end, "bad addr");
 552   return pointer_delta(addr, _region_start) >> Log2RegionSize;
 553 }
 554 
 555 inline ParallelCompactData::RegionData*
 556 ParallelCompactData::addr_to_region_ptr(const HeapWord* addr) const
 557 {
 558   return region(addr_to_region_idx(addr));
 559 }
 560 
 561 inline HeapWord*
 562 ParallelCompactData::region_to_addr(size_t region) const
 563 {
 564   assert(region <= _region_count, "region out of range");
 565   return _region_start + (region << Log2RegionSize);
 566 }
 567 
 568 inline HeapWord*
 569 ParallelCompactData::region_to_addr(const RegionData* region) const
 570 {
 571   return region_to_addr(pointer_delta(region, _region_data,
 572                                       sizeof(RegionData)));
 573 }
 574 
 575 inline HeapWord*
 576 ParallelCompactData::region_to_addr(size_t region, size_t offset) const
 577 {
 578   assert(region <= _region_count, "region out of range");
 579   assert(offset < RegionSize, "offset too big");  // This may be too strict.
 580   return region_to_addr(region) + offset;
 581 }
 582 
 583 inline HeapWord*
 584 ParallelCompactData::region_align_down(HeapWord* addr) const
 585 {
 586   assert(addr >= _region_start, "bad addr");
 587   assert(addr < _region_end + RegionSize, "bad addr");
 588   return (HeapWord*)(size_t(addr) & RegionAddrMask);
 589 }
 590 
 591 inline HeapWord*
 592 ParallelCompactData::region_align_up(HeapWord* addr) const
 593 {
 594   assert(addr >= _region_start, "bad addr");
 595   assert(addr <= _region_end, "bad addr");
 596   return region_align_down(addr + RegionSizeOffsetMask);
 597 }
 598 
 599 inline bool
 600 ParallelCompactData::is_region_aligned(HeapWord* addr) const
 601 {
 602   return region_offset(addr) == 0;
 603 }
 604 
 605 // Abstract closure for use with ParMarkBitMap::iterate(), which will invoke the
 606 // do_addr() method.
 607 //
 608 // The closure is initialized with the number of heap words to process
 609 // (words_remaining()), and becomes 'full' when it reaches 0.  The do_addr()
 610 // methods in subclasses should update the total as words are processed.  Since
 611 // only one subclass actually uses this mechanism to terminate iteration, the
 612 // default initial value is > 0.  The implementation is here and not in the
 613 // single subclass that uses it to avoid making is_full() virtual, and thus
 614 // adding a virtual call per live object.
 615 
 616 class ParMarkBitMapClosure: public StackObj {
 617  public:
 618   typedef ParMarkBitMap::idx_t idx_t;
 619   typedef ParMarkBitMap::IterationStatus IterationStatus;
 620 
 621  public:
 622   inline ParMarkBitMapClosure(ParMarkBitMap* mbm, ParCompactionManager* cm,
 623                               size_t words = max_uintx);
 624 
 625   inline ParCompactionManager* compaction_manager() const;
 626   inline ParMarkBitMap*        bitmap() const;
 627   inline size_t                words_remaining() const;
 628   inline bool                  is_full() const;
 629   inline HeapWord*             source() const;
 630 
 631   inline void                  set_source(HeapWord* addr);
 632 
 633   virtual IterationStatus do_addr(HeapWord* addr, size_t words) = 0;
 634 
 635  protected:
 636   inline void decrement_words_remaining(size_t words);
 637 
 638  private:
 639   ParMarkBitMap* const        _bitmap;
 640   ParCompactionManager* const _compaction_manager;
 641   DEBUG_ONLY(const size_t     _initial_words_remaining;) // Useful in debugger.
 642   size_t                      _words_remaining; // Words left to copy.
 643 
 644  protected:
 645   HeapWord*                   _source;          // Next addr that would be read.
 646 };
 647 
 648 inline
 649 ParMarkBitMapClosure::ParMarkBitMapClosure(ParMarkBitMap* bitmap,
 650                                            ParCompactionManager* cm,
 651                                            size_t words):
 652   _bitmap(bitmap), _compaction_manager(cm)
 653 #ifdef  ASSERT
 654   , _initial_words_remaining(words)
 655 #endif
 656 {
 657   _words_remaining = words;
 658   _source = NULL;
 659 }
 660 
 661 inline ParCompactionManager* ParMarkBitMapClosure::compaction_manager() const {
 662   return _compaction_manager;
 663 }
 664 
 665 inline ParMarkBitMap* ParMarkBitMapClosure::bitmap() const {
 666   return _bitmap;
 667 }
 668 
 669 inline size_t ParMarkBitMapClosure::words_remaining() const {
 670   return _words_remaining;
 671 }
 672 
 673 inline bool ParMarkBitMapClosure::is_full() const {
 674   return words_remaining() == 0;
 675 }
 676 
 677 inline HeapWord* ParMarkBitMapClosure::source() const {
 678   return _source;
 679 }
 680 
 681 inline void ParMarkBitMapClosure::set_source(HeapWord* addr) {
 682   _source = addr;
 683 }
 684 
 685 inline void ParMarkBitMapClosure::decrement_words_remaining(size_t words) {
 686   assert(_words_remaining >= words, "processed too many words");
 687   _words_remaining -= words;
 688 }
 689 
 690 // The UseParallelOldGC collector is a stop-the-world garbage collector that
 691 // does parts of the collection using parallel threads.  The collection includes
 692 // the tenured generation and the young generation.  The permanent generation is
 693 // collected at the same time as the other two generations but the permanent
 694 // generation is collect by a single GC thread.  The permanent generation is
 695 // collected serially because of the requirement that during the processing of a
 696 // klass AAA, any objects reference by AAA must already have been processed.
 697 // This requirement is enforced by a left (lower address) to right (higher
 698 // address) sliding compaction.
 699 //
 700 // There are four phases of the collection.
 701 //
 702 //      - marking phase
 703 //      - summary phase
 704 //      - compacting phase
 705 //      - clean up phase
 706 //
 707 // Roughly speaking these phases correspond, respectively, to
 708 //      - mark all the live objects
 709 //      - calculate the destination of each object at the end of the collection
 710 //      - move the objects to their destination
 711 //      - update some references and reinitialize some variables
 712 //
 713 // These three phases are invoked in PSParallelCompact::invoke_no_policy().  The
 714 // marking phase is implemented in PSParallelCompact::marking_phase() and does a
 715 // complete marking of the heap.  The summary phase is implemented in
 716 // PSParallelCompact::summary_phase().  The move and update phase is implemented
 717 // in PSParallelCompact::compact().
 718 //
 719 // A space that is being collected is divided into regions and with each region
 720 // is associated an object of type ParallelCompactData.  Each region is of a
 721 // fixed size and typically will contain more than 1 object and may have parts
 722 // of objects at the front and back of the region.
 723 //
 724 // region            -----+---------------------+----------
 725 // objects covered   [ AAA  )[ BBB )[ CCC   )[ DDD     )
 726 //
 727 // The marking phase does a complete marking of all live objects in the heap.
 728 // The marking also compiles the size of the data for all live objects covered
 729 // by the region.  This size includes the part of any live object spanning onto
 730 // the region (part of AAA if it is live) from the front, all live objects
 731 // contained in the region (BBB and/or CCC if they are live), and the part of
 732 // any live objects covered by the region that extends off the region (part of
 733 // DDD if it is live).  The marking phase uses multiple GC threads and marking
 734 // is done in a bit array of type ParMarkBitMap.  The marking of the bit map is
 735 // done atomically as is the accumulation of the size of the live objects
 736 // covered by a region.
 737 //
 738 // The summary phase calculates the total live data to the left of each region
 739 // XXX.  Based on that total and the bottom of the space, it can calculate the
 740 // starting location of the live data in XXX.  The summary phase calculates for
 741 // each region XXX quantites such as
 742 //
 743 //      - the amount of live data at the beginning of a region from an object
 744 //        entering the region.
 745 //      - the location of the first live data on the region
 746 //      - a count of the number of regions receiving live data from XXX.
 747 //
 748 // See ParallelCompactData for precise details.  The summary phase also
 749 // calculates the dense prefix for the compaction.  The dense prefix is a
 750 // portion at the beginning of the space that is not moved.  The objects in the
 751 // dense prefix do need to have their object references updated.  See method
 752 // summarize_dense_prefix().
 753 //
 754 // The summary phase is done using 1 GC thread.
 755 //
 756 // The compaction phase moves objects to their new location and updates all
 757 // references in the object.
 758 //
 759 // A current exception is that objects that cross a region boundary are moved
 760 // but do not have their references updated.  References are not updated because
 761 // it cannot easily be determined if the klass pointer KKK for the object AAA
 762 // has been updated.  KKK likely resides in a region to the left of the region
 763 // containing AAA.  These AAA's have there references updated at the end in a
 764 // clean up phase.  See the method PSParallelCompact::update_deferred_objects().
 765 // An alternate strategy is being investigated for this deferral of updating.
 766 //
 767 // Compaction is done on a region basis.  A region that is ready to be filled is
 768 // put on a ready list and GC threads take region off the list and fill them.  A
 769 // region is ready to be filled if it empty of live objects.  Such a region may
 770 // have been initially empty (only contained dead objects) or may have had all
 771 // its live objects copied out already.  A region that compacts into itself is
 772 // also ready for filling.  The ready list is initially filled with empty
 773 // regions and regions compacting into themselves.  There is always at least 1
 774 // region that can be put on the ready list.  The regions are atomically added
 775 // and removed from the ready list.
 776 
 777 class PSParallelCompact : AllStatic {
 778  public:
 779   // Convenient access to type names.
 780   typedef ParMarkBitMap::idx_t idx_t;
 781   typedef ParallelCompactData::RegionData RegionData;
 782 
 783   typedef enum {
 784     perm_space_id, old_space_id, eden_space_id,
 785     from_space_id, to_space_id, last_space_id
 786   } SpaceId;
 787 
 788  public:
 789   // Inline closure decls
 790   //
 791   class IsAliveClosure: public BoolObjectClosure {
 792    public:
 793     virtual void do_object(oop p);
 794     virtual bool do_object_b(oop p);
 795   };
 796 
 797   class KeepAliveClosure: public OopClosure {
 798    private:
 799     ParCompactionManager* _compaction_manager;
 800    protected:
 801     template <class T> inline void do_oop_work(T* p);
 802    public:
 803     KeepAliveClosure(ParCompactionManager* cm) : _compaction_manager(cm) { }
 804     virtual void do_oop(oop* p);
 805     virtual void do_oop(narrowOop* p);
 806   };
 807 
 808   // Current unused
 809   class FollowRootClosure: public OopsInGenClosure {
 810    private:
 811     ParCompactionManager* _compaction_manager;
 812    public:
 813     FollowRootClosure(ParCompactionManager* cm) : _compaction_manager(cm) { }
 814     virtual void do_oop(oop* p);
 815     virtual void do_oop(narrowOop* p);
 816  };
 817 
 818   class FollowStackClosure: public VoidClosure {
 819    private:
 820     ParCompactionManager* _compaction_manager;
 821    public:
 822     FollowStackClosure(ParCompactionManager* cm) : _compaction_manager(cm) { }
 823     virtual void do_void();
 824   };
 825 
 826   class AdjustPointerClosure: public OopsInGenClosure {
 827    private:
 828     bool _is_root;
 829    public:
 830     AdjustPointerClosure(bool is_root) : _is_root(is_root) { }
 831     virtual void do_oop(oop* p);
 832     virtual void do_oop(narrowOop* p);
 833     // do not walk from thread stacks to the code cache on this phase
 834     virtual void do_code_blob(CodeBlob* cb) const { }
 835   };
 836 
 837   friend class KeepAliveClosure;
 838   friend class FollowStackClosure;
 839   friend class AdjustPointerClosure;
 840   friend class FollowRootClosure;
 841   friend class instanceKlassKlass;
 842   friend class RefProcTaskProxy;
 843 
 844  private:
 845   static STWGCTimer           _gc_timer;
 846   static ParallelOldTracer    _gc_tracer;
 847   static elapsedTimer         _accumulated_time;
 848   static unsigned int         _total_invocations;
 849   static unsigned int         _maximum_compaction_gc_num;
 850   static jlong                _time_of_last_gc;   // ms
 851   static CollectorCounters*   _counters;
 852   static ParMarkBitMap        _mark_bitmap;
 853   static ParallelCompactData  _summary_data;
 854   static IsAliveClosure       _is_alive_closure;
 855   static SpaceInfo            _space_info[last_space_id];
 856   static bool                 _print_phases;
 857   static AdjustPointerClosure _adjust_root_pointer_closure;
 858   static AdjustPointerClosure _adjust_pointer_closure;
 859 
 860   // Reference processing (used in ...follow_contents)
 861   static ReferenceProcessor*  _ref_processor;
 862 
 863   // Updated location of intArrayKlassObj.
 864   static klassOop _updated_int_array_klass_obj;
 865 
 866   // Values computed at initialization and used by dead_wood_limiter().
 867   static double _dwl_mean;
 868   static double _dwl_std_dev;
 869   static double _dwl_first_term;
 870   static double _dwl_adjustment;
 871 #ifdef  ASSERT
 872   static bool   _dwl_initialized;
 873 #endif  // #ifdef ASSERT
 874 
 875  private:
 876   // Closure accessors
 877   static OopClosure* adjust_pointer_closure()      { return (OopClosure*)&_adjust_pointer_closure; }
 878   static OopClosure* adjust_root_pointer_closure() { return (OopClosure*)&_adjust_root_pointer_closure; }
 879   static BoolObjectClosure* is_alive_closure()     { return (BoolObjectClosure*)&_is_alive_closure; }
 880 
 881   static void initialize_space_info();
 882 
 883   // Return true if details about individual phases should be printed.
 884   static inline bool print_phases();
 885 
 886   // Clear the marking bitmap and summary data that cover the specified space.
 887   static void clear_data_covering_space(SpaceId id);
 888 
 889   static void pre_compact(PreGCValues* pre_gc_values);
 890   static void post_compact();
 891 
 892   // Mark live objects
 893   static void marking_phase(ParCompactionManager* cm,
 894                             bool maximum_heap_compaction,
 895                             ParallelOldTracer *gc_tracer);
 896   static void follow_weak_klass_links();
 897   static void follow_mdo_weak_refs();
 898 
 899   template <class T> static inline void adjust_pointer(T* p, bool is_root);
 900   static void adjust_root_pointer(oop* p) { adjust_pointer(p, true); }
 901 
 902   template <class T>
 903   static inline void follow_root(ParCompactionManager* cm, T* p);
 904 
 905   // Compute the dense prefix for the designated space.  This is an experimental
 906   // implementation currently not used in production.
 907   static HeapWord* compute_dense_prefix_via_density(const SpaceId id,
 908                                                     bool maximum_compaction);
 909 
 910   // Methods used to compute the dense prefix.
 911 
 912   // Compute the value of the normal distribution at x = density.  The mean and
 913   // standard deviation are values saved by initialize_dead_wood_limiter().
 914   static inline double normal_distribution(double density);
 915 
 916   // Initialize the static vars used by dead_wood_limiter().
 917   static void initialize_dead_wood_limiter();
 918 
 919   // Return the percentage of space that can be treated as "dead wood" (i.e.,
 920   // not reclaimed).
 921   static double dead_wood_limiter(double density, size_t min_percent);
 922 
 923   // Find the first (left-most) region in the range [beg, end) that has at least
 924   // dead_words of dead space to the left.  The argument beg must be the first
 925   // region in the space that is not completely live.
 926   static RegionData* dead_wood_limit_region(const RegionData* beg,
 927                                             const RegionData* end,
 928                                             size_t dead_words);
 929 
 930   // Return a pointer to the first region in the range [beg, end) that is not
 931   // completely full.
 932   static RegionData* first_dead_space_region(const RegionData* beg,
 933                                              const RegionData* end);
 934 
 935   // Return a value indicating the benefit or 'yield' if the compacted region
 936   // were to start (or equivalently if the dense prefix were to end) at the
 937   // candidate region.  Higher values are better.
 938   //
 939   // The value is based on the amount of space reclaimed vs. the costs of (a)
 940   // updating references in the dense prefix plus (b) copying objects and
 941   // updating references in the compacted region.
 942   static inline double reclaimed_ratio(const RegionData* const candidate,
 943                                        HeapWord* const bottom,
 944                                        HeapWord* const top,
 945                                        HeapWord* const new_top);
 946 
 947   // Compute the dense prefix for the designated space.
 948   static HeapWord* compute_dense_prefix(const SpaceId id,
 949                                         bool maximum_compaction);
 950 
 951   // Return true if dead space crosses onto the specified Region; bit must be
 952   // the bit index corresponding to the first word of the Region.
 953   static inline bool dead_space_crosses_boundary(const RegionData* region,
 954                                                  idx_t bit);
 955 
 956   // Summary phase utility routine to fill dead space (if any) at the dense
 957   // prefix boundary.  Should only be called if the the dense prefix is
 958   // non-empty.
 959   static void fill_dense_prefix_end(SpaceId id);
 960 
 961   // Clear the summary data source_region field for the specified addresses.
 962   static void clear_source_region(HeapWord* beg_addr, HeapWord* end_addr);
 963 
 964 #ifndef PRODUCT
 965   // Routines to provoke splitting a young gen space (ParallelOldGCSplitALot).
 966 
 967   // Fill the region [start, start + words) with live object(s).  Only usable
 968   // for the old and permanent generations.
 969   static void fill_with_live_objects(SpaceId id, HeapWord* const start,
 970                                      size_t words);
 971   // Include the new objects in the summary data.
 972   static void summarize_new_objects(SpaceId id, HeapWord* start);
 973 
 974   // Add live objects to a survivor space since it's rare that both survivors
 975   // are non-empty.
 976   static void provoke_split_fill_survivor(SpaceId id);
 977 
 978   // Add live objects and/or choose the dense prefix to provoke splitting.
 979   static void provoke_split(bool & maximum_compaction);
 980 #endif
 981 
 982   static void summarize_spaces_quick();
 983   static void summarize_space(SpaceId id, bool maximum_compaction);
 984   static void summary_phase(ParCompactionManager* cm, bool maximum_compaction);
 985 
 986   // Adjust addresses in roots.  Does not adjust addresses in heap.
 987   static void adjust_roots();
 988 
 989   // Serial code executed in preparation for the compaction phase.
 990   static void compact_prologue();
 991 
 992   // Move objects to new locations.
 993   static void compact_perm(ParCompactionManager* cm);
 994   static void compact();
 995 
 996   // Add available regions to the stack and draining tasks to the task queue.
 997   static void enqueue_region_draining_tasks(GCTaskQueue* q,
 998                                             uint parallel_gc_threads);
 999 
1000   // Add dense prefix update tasks to the task queue.
1001   static void enqueue_dense_prefix_tasks(GCTaskQueue* q,
1002                                          uint parallel_gc_threads);
1003 
1004   // Add region stealing tasks to the task queue.
1005   static void enqueue_region_stealing_tasks(
1006                                        GCTaskQueue* q,
1007                                        ParallelTaskTerminator* terminator_ptr,
1008                                        uint parallel_gc_threads);
1009 
1010   // If objects are left in eden after a collection, try to move the boundary
1011   // and absorb them into the old gen.  Returns true if eden was emptied.
1012   static bool absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
1013                                          PSYoungGen* young_gen,
1014                                          PSOldGen* old_gen);
1015 
1016   // Reset time since last full gc
1017   static void reset_millis_since_last_gc();
1018 
1019  protected:
1020 #ifdef VALIDATE_MARK_SWEEP
1021   static GrowableArray<void*>*           _root_refs_stack;
1022   static GrowableArray<oop> *            _live_oops;
1023   static GrowableArray<oop> *            _live_oops_moved_to;
1024   static GrowableArray<size_t>*          _live_oops_size;
1025   static size_t                          _live_oops_index;
1026   static size_t                          _live_oops_index_at_perm;
1027   static GrowableArray<void*>*           _other_refs_stack;
1028   static GrowableArray<void*>*           _adjusted_pointers;
1029   static bool                            _pointer_tracking;
1030   static bool                            _root_tracking;
1031 
1032   // The following arrays are saved since the time of the last GC and
1033   // assist in tracking down problems where someone has done an errant
1034   // store into the heap, usually to an oop that wasn't properly
1035   // handleized across a GC. If we crash or otherwise fail before the
1036   // next GC, we can query these arrays to find out the object we had
1037   // intended to do the store to (assuming it is still alive) and the
1038   // offset within that object. Covered under RecordMarkSweepCompaction.
1039   static GrowableArray<HeapWord*> *      _cur_gc_live_oops;
1040   static GrowableArray<HeapWord*> *      _cur_gc_live_oops_moved_to;
1041   static GrowableArray<size_t>*          _cur_gc_live_oops_size;
1042   static GrowableArray<HeapWord*> *      _last_gc_live_oops;
1043   static GrowableArray<HeapWord*> *      _last_gc_live_oops_moved_to;
1044   static GrowableArray<size_t>*          _last_gc_live_oops_size;
1045 #endif
1046 
1047  public:
1048   class MarkAndPushClosure: public OopClosure {
1049    private:
1050     ParCompactionManager* _compaction_manager;
1051    public:
1052     MarkAndPushClosure(ParCompactionManager* cm) : _compaction_manager(cm) { }
1053     virtual void do_oop(oop* p);
1054     virtual void do_oop(narrowOop* p);
1055   };
1056 
1057   PSParallelCompact();
1058 
1059   // Convenient accessor for Universe::heap().
1060   static ParallelScavengeHeap* gc_heap() {
1061     return (ParallelScavengeHeap*)Universe::heap();
1062   }
1063 
1064   static void invoke(bool maximum_heap_compaction);
1065   static bool invoke_no_policy(bool maximum_heap_compaction);
1066 
1067   static void post_initialize();
1068   // Perform initialization for PSParallelCompact that requires
1069   // allocations.  This should be called during the VM initialization
1070   // at a pointer where it would be appropriate to return a JNI_ENOMEM
1071   // in the event of a failure.
1072   static bool initialize();
1073 
1074   // Public accessors
1075   static elapsedTimer* accumulated_time() { return &_accumulated_time; }
1076   static unsigned int total_invocations() { return _total_invocations; }
1077   static CollectorCounters* counters()    { return _counters; }
1078 
1079   // Used to add tasks
1080   static GCTaskManager* const gc_task_manager();
1081   static klassOop updated_int_array_klass_obj() {
1082     return _updated_int_array_klass_obj;
1083   }
1084 
1085   // Marking support
1086   static inline bool mark_obj(oop obj);
1087   // Check mark and maybe push on marking stack
1088   template <class T> static inline void mark_and_push(ParCompactionManager* cm,
1089                                                       T* p);
1090 
1091   // Compaction support.
1092   // Return true if p is in the range [beg_addr, end_addr).
1093   static inline bool is_in(HeapWord* p, HeapWord* beg_addr, HeapWord* end_addr);
1094   static inline bool is_in(oop* p, HeapWord* beg_addr, HeapWord* end_addr);
1095 
1096   // Convenience wrappers for per-space data kept in _space_info.
1097   static inline MutableSpace*     space(SpaceId space_id);
1098   static inline HeapWord*         new_top(SpaceId space_id);
1099   static inline HeapWord*         dense_prefix(SpaceId space_id);
1100   static inline ObjectStartArray* start_array(SpaceId space_id);
1101 
1102   // Return true if the klass should be updated.
1103   static inline bool should_update_klass(klassOop k);
1104 
1105   // Move and update the live objects in the specified space.
1106   static void move_and_update(ParCompactionManager* cm, SpaceId space_id);
1107 
1108   // Process the end of the given region range in the dense prefix.
1109   // This includes saving any object not updated.
1110   static void dense_prefix_regions_epilogue(ParCompactionManager* cm,
1111                                             size_t region_start_index,
1112                                             size_t region_end_index,
1113                                             idx_t exiting_object_offset,
1114                                             idx_t region_offset_start,
1115                                             idx_t region_offset_end);
1116 
1117   // Update a region in the dense prefix.  For each live object
1118   // in the region, update it's interior references.  For each
1119   // dead object, fill it with deadwood. Dead space at the end
1120   // of a region range will be filled to the start of the next
1121   // live object regardless of the region_index_end.  None of the
1122   // objects in the dense prefix move and dead space is dead
1123   // (holds only dead objects that don't need any processing), so
1124   // dead space can be filled in any order.
1125   static void update_and_deadwood_in_dense_prefix(ParCompactionManager* cm,
1126                                                   SpaceId space_id,
1127                                                   size_t region_index_start,
1128                                                   size_t region_index_end);
1129 
1130   // Return the address of the count + 1st live word in the range [beg, end).
1131   static HeapWord* skip_live_words(HeapWord* beg, HeapWord* end, size_t count);
1132 
1133   // Return the address of the word to be copied to dest_addr, which must be
1134   // aligned to a region boundary.
1135   static HeapWord* first_src_addr(HeapWord* const dest_addr,
1136                                   SpaceId src_space_id,
1137                                   size_t src_region_idx);
1138 
1139   // Determine the next source region, set closure.source() to the start of the
1140   // new region return the region index.  Parameter end_addr is the address one
1141   // beyond the end of source range just processed.  If necessary, switch to a
1142   // new source space and set src_space_id (in-out parameter) and src_space_top
1143   // (out parameter) accordingly.
1144   static size_t next_src_region(MoveAndUpdateClosure& closure,
1145                                 SpaceId& src_space_id,
1146                                 HeapWord*& src_space_top,
1147                                 HeapWord* end_addr);
1148 
1149   // Decrement the destination count for each non-empty source region in the
1150   // range [beg_region, region(region_align_up(end_addr))).  If the destination
1151   // count for a region goes to 0 and it needs to be filled, enqueue it.
1152   static void decrement_destination_counts(ParCompactionManager* cm,
1153                                            SpaceId src_space_id,
1154                                            size_t beg_region,
1155                                            HeapWord* end_addr);
1156 
1157   // Fill a region, copying objects from one or more source regions.
1158   static void fill_region(ParCompactionManager* cm, size_t region_idx);
1159   static void fill_and_update_region(ParCompactionManager* cm, size_t region) {
1160     fill_region(cm, region);
1161   }
1162 
1163   // Update the deferred objects in the space.
1164   static void update_deferred_objects(ParCompactionManager* cm, SpaceId id);
1165 
1166   static ParMarkBitMap* mark_bitmap() { return &_mark_bitmap; }
1167   static ParallelCompactData& summary_data() { return _summary_data; }
1168 
1169   static inline void adjust_pointer(oop* p)       { adjust_pointer(p, false); }
1170   static inline void adjust_pointer(narrowOop* p) { adjust_pointer(p, false); }
1171 
1172   // Reference Processing
1173   static ReferenceProcessor* const ref_processor() { return _ref_processor; }
1174 
1175   static STWGCTimer* gc_timer() { return &_gc_timer; }
1176 
1177   // Return the SpaceId for the given address.
1178   static SpaceId space_id(HeapWord* addr);
1179 
1180   // Time since last full gc (in milliseconds).
1181   static jlong millis_since_last_gc();
1182 
1183 #ifdef VALIDATE_MARK_SWEEP
1184   static void track_adjusted_pointer(void* p, bool isroot);
1185   static void check_adjust_pointer(void* p);
1186   static void track_interior_pointers(oop obj);
1187   static void check_interior_pointers();
1188 
1189   static void reset_live_oop_tracking(bool at_perm);
1190   static void register_live_oop(oop p, size_t size);
1191   static void validate_live_oop(oop p, size_t size);
1192   static void live_oop_moved_to(HeapWord* q, size_t size, HeapWord* compaction_top);
1193   static void compaction_complete();
1194 
1195   // Querying operation of RecordMarkSweepCompaction results.
1196   // Finds and prints the current base oop and offset for a word
1197   // within an oop that was live during the last GC. Helpful for
1198   // tracking down heap stomps.
1199   static void print_new_location_of_heap_address(HeapWord* q);
1200 #endif  // #ifdef VALIDATE_MARK_SWEEP
1201 
1202   // Call backs for class unloading
1203   // Update subklass/sibling/implementor links at end of marking.
1204   static void revisit_weak_klass_link(ParCompactionManager* cm, Klass* k);
1205 
1206   // Clear unmarked oops in MDOs at the end of marking.
1207   static void revisit_mdo(ParCompactionManager* cm, DataLayout* p);
1208 
1209 #ifndef PRODUCT
1210   // Debugging support.
1211   static const char* space_names[last_space_id];
1212   static void print_region_ranges();
1213   static void print_dense_prefix_stats(const char* const algorithm,
1214                                        const SpaceId id,
1215                                        const bool maximum_compaction,
1216                                        HeapWord* const addr);
1217   static void summary_phase_msg(SpaceId dst_space_id,
1218                                 HeapWord* dst_beg, HeapWord* dst_end,
1219                                 SpaceId src_space_id,
1220                                 HeapWord* src_beg, HeapWord* src_end);
1221 #endif  // #ifndef PRODUCT
1222 
1223 #ifdef  ASSERT
1224   // Sanity check the new location of a word in the heap.
1225   static inline void check_new_location(HeapWord* old_addr, HeapWord* new_addr);
1226   // Verify that all the regions have been emptied.
1227   static void verify_complete(SpaceId space_id);
1228 #endif  // #ifdef ASSERT
1229 };
1230 
1231 inline bool PSParallelCompact::mark_obj(oop obj) {
1232   const int obj_size = obj->size();
1233   if (mark_bitmap()->mark_obj(obj, obj_size)) {
1234     _summary_data.add_obj(obj, obj_size);
1235     return true;
1236   } else {
1237     return false;
1238   }
1239 }
1240 
1241 template <class T>
1242 inline void PSParallelCompact::follow_root(ParCompactionManager* cm, T* p) {
1243   assert(!Universe::heap()->is_in_reserved(p),
1244          "roots shouldn't be things within the heap");
1245 #ifdef VALIDATE_MARK_SWEEP
1246   if (ValidateMarkSweep) {
1247     guarantee(!_root_refs_stack->contains(p), "should only be in here once");
1248     _root_refs_stack->push(p);
1249   }
1250 #endif
1251   T heap_oop = oopDesc::load_heap_oop(p);
1252   if (!oopDesc::is_null(heap_oop)) {
1253     oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
1254     if (mark_bitmap()->is_unmarked(obj)) {
1255       if (mark_obj(obj)) {
1256         obj->follow_contents(cm);
1257       }
1258     }
1259   }
1260   cm->follow_marking_stacks();
1261 }
1262 
1263 template <class T>
1264 inline void PSParallelCompact::mark_and_push(ParCompactionManager* cm, T* p) {
1265   T heap_oop = oopDesc::load_heap_oop(p);
1266   if (!oopDesc::is_null(heap_oop)) {
1267     oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
1268     if (mark_bitmap()->is_unmarked(obj) && mark_obj(obj)) {
1269       cm->push(obj);
1270     }
1271   }
1272 }
1273 
1274 template <class T>
1275 inline void PSParallelCompact::adjust_pointer(T* p, bool isroot) {
1276   T heap_oop = oopDesc::load_heap_oop(p);
1277   if (!oopDesc::is_null(heap_oop)) {
1278     oop obj     = oopDesc::decode_heap_oop_not_null(heap_oop);
1279     oop new_obj = (oop)summary_data().calc_new_pointer(obj);
1280     assert(new_obj != NULL ||                     // is forwarding ptr?
1281            obj->is_shared(),                      // never forwarded?
1282            "should be forwarded");
1283     // Just always do the update unconditionally?
1284     if (new_obj != NULL) {
1285       assert(Universe::heap()->is_in_reserved(new_obj),
1286              "should be in object space");
1287       oopDesc::encode_store_heap_oop_not_null(p, new_obj);
1288     }
1289   }
1290   VALIDATE_MARK_SWEEP_ONLY(track_adjusted_pointer(p, isroot));
1291 }
1292 
1293 template <class T>
1294 inline void PSParallelCompact::KeepAliveClosure::do_oop_work(T* p) {
1295 #ifdef VALIDATE_MARK_SWEEP
1296   if (ValidateMarkSweep) {
1297     if (!Universe::heap()->is_in_reserved(p)) {
1298       _root_refs_stack->push(p);
1299     } else {
1300       _other_refs_stack->push(p);
1301     }
1302   }
1303 #endif
1304   mark_and_push(_compaction_manager, p);
1305 }
1306 
1307 inline bool PSParallelCompact::print_phases() {
1308   return _print_phases;
1309 }
1310 
1311 inline double PSParallelCompact::normal_distribution(double density) {
1312   assert(_dwl_initialized, "uninitialized");
1313   const double squared_term = (density - _dwl_mean) / _dwl_std_dev;
1314   return _dwl_first_term * exp(-0.5 * squared_term * squared_term);
1315 }
1316 
1317 inline bool
1318 PSParallelCompact::dead_space_crosses_boundary(const RegionData* region,
1319                                                idx_t bit)
1320 {
1321   assert(bit > 0, "cannot call this for the first bit/region");
1322   assert(_summary_data.region_to_addr(region) == _mark_bitmap.bit_to_addr(bit),
1323          "sanity check");
1324 
1325   // Dead space crosses the boundary if (1) a partial object does not extend
1326   // onto the region, (2) an object does not start at the beginning of the
1327   // region, and (3) an object does not end at the end of the prior region.
1328   return region->partial_obj_size() == 0 &&
1329     !_mark_bitmap.is_obj_beg(bit) &&
1330     !_mark_bitmap.is_obj_end(bit - 1);
1331 }
1332 
1333 inline bool
1334 PSParallelCompact::is_in(HeapWord* p, HeapWord* beg_addr, HeapWord* end_addr) {
1335   return p >= beg_addr && p < end_addr;
1336 }
1337 
1338 inline bool
1339 PSParallelCompact::is_in(oop* p, HeapWord* beg_addr, HeapWord* end_addr) {
1340   return is_in((HeapWord*)p, beg_addr, end_addr);
1341 }
1342 
1343 inline MutableSpace* PSParallelCompact::space(SpaceId id) {
1344   assert(id < last_space_id, "id out of range");
1345   return _space_info[id].space();
1346 }
1347 
1348 inline HeapWord* PSParallelCompact::new_top(SpaceId id) {
1349   assert(id < last_space_id, "id out of range");
1350   return _space_info[id].new_top();
1351 }
1352 
1353 inline HeapWord* PSParallelCompact::dense_prefix(SpaceId id) {
1354   assert(id < last_space_id, "id out of range");
1355   return _space_info[id].dense_prefix();
1356 }
1357 
1358 inline ObjectStartArray* PSParallelCompact::start_array(SpaceId id) {
1359   assert(id < last_space_id, "id out of range");
1360   return _space_info[id].start_array();
1361 }
1362 
1363 inline bool PSParallelCompact::should_update_klass(klassOop k) {
1364   return ((HeapWord*) k) >= dense_prefix(perm_space_id);
1365 }
1366 
1367 #ifdef ASSERT
1368 inline void
1369 PSParallelCompact::check_new_location(HeapWord* old_addr, HeapWord* new_addr)
1370 {
1371   assert(old_addr >= new_addr || space_id(old_addr) != space_id(new_addr),
1372          "must move left or to a different space");
1373   assert(is_object_aligned((intptr_t)old_addr) && is_object_aligned((intptr_t)new_addr),
1374          "checking alignment");
1375 }
1376 #endif // ASSERT
1377 
1378 class MoveAndUpdateClosure: public ParMarkBitMapClosure {
1379  public:
1380   inline MoveAndUpdateClosure(ParMarkBitMap* bitmap, ParCompactionManager* cm,
1381                               ObjectStartArray* start_array,
1382                               HeapWord* destination, size_t words);
1383 
1384   // Accessors.
1385   HeapWord* destination() const         { return _destination; }
1386 
1387   // If the object will fit (size <= words_remaining()), copy it to the current
1388   // destination, update the interior oops and the start array and return either
1389   // full (if the closure is full) or incomplete.  If the object will not fit,
1390   // return would_overflow.
1391   virtual IterationStatus do_addr(HeapWord* addr, size_t size);
1392 
1393   // Copy enough words to fill this closure, starting at source().  Interior
1394   // oops and the start array are not updated.  Return full.
1395   IterationStatus copy_until_full();
1396 
1397   // Copy enough words to fill this closure or to the end of an object,
1398   // whichever is smaller, starting at source().  Interior oops and the start
1399   // array are not updated.
1400   void copy_partial_obj();
1401 
1402  protected:
1403   // Update variables to indicate that word_count words were processed.
1404   inline void update_state(size_t word_count);
1405 
1406  protected:
1407   ObjectStartArray* const _start_array;
1408   HeapWord*               _destination;         // Next addr to be written.
1409 };
1410 
1411 inline
1412 MoveAndUpdateClosure::MoveAndUpdateClosure(ParMarkBitMap* bitmap,
1413                                            ParCompactionManager* cm,
1414                                            ObjectStartArray* start_array,
1415                                            HeapWord* destination,
1416                                            size_t words) :
1417   ParMarkBitMapClosure(bitmap, cm, words), _start_array(start_array)
1418 {
1419   _destination = destination;
1420 }
1421 
1422 inline void MoveAndUpdateClosure::update_state(size_t words)
1423 {
1424   decrement_words_remaining(words);
1425   _source += words;
1426   _destination += words;
1427 }
1428 
1429 class UpdateOnlyClosure: public ParMarkBitMapClosure {
1430  private:
1431   const PSParallelCompact::SpaceId _space_id;
1432   ObjectStartArray* const          _start_array;
1433 
1434  public:
1435   UpdateOnlyClosure(ParMarkBitMap* mbm,
1436                     ParCompactionManager* cm,
1437                     PSParallelCompact::SpaceId space_id);
1438 
1439   // Update the object.
1440   virtual IterationStatus do_addr(HeapWord* addr, size_t words);
1441 
1442   inline void do_addr(HeapWord* addr);
1443 };
1444 
1445 inline void UpdateOnlyClosure::do_addr(HeapWord* addr)
1446 {
1447   _start_array->allocate_block(addr);
1448   oop(addr)->update_contents(compaction_manager());
1449 }
1450 
1451 class FillClosure: public ParMarkBitMapClosure
1452 {
1453 public:
1454   FillClosure(ParCompactionManager* cm, PSParallelCompact::SpaceId space_id) :
1455     ParMarkBitMapClosure(PSParallelCompact::mark_bitmap(), cm),
1456     _start_array(PSParallelCompact::start_array(space_id))
1457   {
1458     assert(space_id == PSParallelCompact::perm_space_id ||
1459            space_id == PSParallelCompact::old_space_id,
1460            "cannot use FillClosure in the young gen");
1461   }
1462 
1463   virtual IterationStatus do_addr(HeapWord* addr, size_t size) {
1464     CollectedHeap::fill_with_objects(addr, size);
1465     HeapWord* const end = addr + size;
1466     do {
1467       _start_array->allocate_block(addr);
1468       addr += oop(addr)->size();
1469     } while (addr < end);
1470     return ParMarkBitMap::incomplete;
1471   }
1472 
1473 private:
1474   ObjectStartArray* const _start_array;
1475 };
1476 
1477 #endif // SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_PSPARALLELCOMPACT_HPP