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
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "classfile/symbolTable.hpp"
  27 #include "classfile/systemDictionary.hpp"
  28 #include "code/codeCache.hpp"
  29 #include "gc_implementation/parallelScavenge/gcTaskManager.hpp"
  30 #include "gc_implementation/parallelScavenge/generationSizer.hpp"
  31 #include "gc_implementation/parallelScavenge/parallelScavengeHeap.inline.hpp"
  32 #include "gc_implementation/parallelScavenge/pcTasks.hpp"
  33 #include "gc_implementation/parallelScavenge/psAdaptiveSizePolicy.hpp"
  34 #include "gc_implementation/parallelScavenge/psCompactionManager.inline.hpp"
  35 #include "gc_implementation/parallelScavenge/psMarkSweep.hpp"
  36 #include "gc_implementation/parallelScavenge/psMarkSweepDecorator.hpp"
  37 #include "gc_implementation/parallelScavenge/psOldGen.hpp"
  38 #include "gc_implementation/parallelScavenge/psParallelCompact.hpp"
  39 #include "gc_implementation/parallelScavenge/psPromotionManager.inline.hpp"
  40 #include "gc_implementation/parallelScavenge/psScavenge.hpp"
  41 #include "gc_implementation/parallelScavenge/psYoungGen.hpp"
  42 #include "gc_implementation/shared/isGCActiveMark.hpp"
  43 #include "gc_interface/gcCause.hpp"
  44 #include "memory/gcLocker.inline.hpp"
  45 #include "memory/referencePolicy.hpp"
  46 #include "memory/referenceProcessor.hpp"
  47 #include "oops/methodData.hpp"
  48 #include "oops/oop.inline.hpp"
  49 #include "oops/oop.pcgc.inline.hpp"
  50 #include "runtime/fprofiler.hpp"
  51 #include "runtime/safepoint.hpp"
  52 #include "runtime/vmThread.hpp"
  53 #include "services/management.hpp"
  54 #include "services/memoryService.hpp"
  55 #include "services/memTracker.hpp"
  56 #include "utilities/events.hpp"
  57 #include "utilities/stack.inline.hpp"
  58 
  59 #include <math.h>
  60 
  61 // All sizes are in HeapWords.
  62 const size_t ParallelCompactData::Log2RegionSize  = 9; // 512 words
  63 const size_t ParallelCompactData::RegionSize      = (size_t)1 << Log2RegionSize;
  64 const size_t ParallelCompactData::RegionSizeBytes =
  65   RegionSize << LogHeapWordSize;
  66 const size_t ParallelCompactData::RegionSizeOffsetMask = RegionSize - 1;
  67 const size_t ParallelCompactData::RegionAddrOffsetMask = RegionSizeBytes - 1;
  68 const size_t ParallelCompactData::RegionAddrMask  = ~RegionAddrOffsetMask;
  69 
  70 const ParallelCompactData::RegionData::region_sz_t
  71 ParallelCompactData::RegionData::dc_shift = 27;
  72 
  73 const ParallelCompactData::RegionData::region_sz_t
  74 ParallelCompactData::RegionData::dc_mask = ~0U << dc_shift;
  75 
  76 const ParallelCompactData::RegionData::region_sz_t
  77 ParallelCompactData::RegionData::dc_one = 0x1U << dc_shift;
  78 
  79 const ParallelCompactData::RegionData::region_sz_t
  80 ParallelCompactData::RegionData::los_mask = ~dc_mask;
  81 
  82 const ParallelCompactData::RegionData::region_sz_t
  83 ParallelCompactData::RegionData::dc_claimed = 0x8U << dc_shift;
  84 
  85 const ParallelCompactData::RegionData::region_sz_t
  86 ParallelCompactData::RegionData::dc_completed = 0xcU << dc_shift;
  87 
  88 SpaceInfo PSParallelCompact::_space_info[PSParallelCompact::last_space_id];
  89 bool      PSParallelCompact::_print_phases = false;
  90 
  91 ReferenceProcessor* PSParallelCompact::_ref_processor = NULL;
  92 Klass*              PSParallelCompact::_updated_int_array_klass_obj = NULL;
  93 
  94 double PSParallelCompact::_dwl_mean;
  95 double PSParallelCompact::_dwl_std_dev;
  96 double PSParallelCompact::_dwl_first_term;
  97 double PSParallelCompact::_dwl_adjustment;
  98 #ifdef  ASSERT
  99 bool   PSParallelCompact::_dwl_initialized = false;
 100 #endif  // #ifdef ASSERT
 101 
 102 void SplitInfo::record(size_t src_region_idx, size_t partial_obj_size,
 103                        HeapWord* destination)
 104 {
 105   assert(src_region_idx != 0, "invalid src_region_idx");
 106   assert(partial_obj_size != 0, "invalid partial_obj_size argument");
 107   assert(destination != NULL, "invalid destination argument");
 108 
 109   _src_region_idx = src_region_idx;
 110   _partial_obj_size = partial_obj_size;
 111   _destination = destination;
 112 
 113   // These fields may not be updated below, so make sure they're clear.
 114   assert(_dest_region_addr == NULL, "should have been cleared");
 115   assert(_first_src_addr == NULL, "should have been cleared");
 116 
 117   // Determine the number of destination regions for the partial object.
 118   HeapWord* const last_word = destination + partial_obj_size - 1;
 119   const ParallelCompactData& sd = PSParallelCompact::summary_data();
 120   HeapWord* const beg_region_addr = sd.region_align_down(destination);
 121   HeapWord* const end_region_addr = sd.region_align_down(last_word);
 122 
 123   if (beg_region_addr == end_region_addr) {
 124     // One destination region.
 125     _destination_count = 1;
 126     if (end_region_addr == destination) {
 127       // The destination falls on a region boundary, thus the first word of the
 128       // partial object will be the first word copied to the destination region.
 129       _dest_region_addr = end_region_addr;
 130       _first_src_addr = sd.region_to_addr(src_region_idx);
 131     }
 132   } else {
 133     // Two destination regions.  When copied, the partial object will cross a
 134     // destination region boundary, so a word somewhere within the partial
 135     // object will be the first word copied to the second destination region.
 136     _destination_count = 2;
 137     _dest_region_addr = end_region_addr;
 138     const size_t ofs = pointer_delta(end_region_addr, destination);
 139     assert(ofs < _partial_obj_size, "sanity");
 140     _first_src_addr = sd.region_to_addr(src_region_idx) + ofs;
 141   }
 142 }
 143 
 144 void SplitInfo::clear()
 145 {
 146   _src_region_idx = 0;
 147   _partial_obj_size = 0;
 148   _destination = NULL;
 149   _destination_count = 0;
 150   _dest_region_addr = NULL;
 151   _first_src_addr = NULL;
 152   assert(!is_valid(), "sanity");
 153 }
 154 
 155 #ifdef  ASSERT
 156 void SplitInfo::verify_clear()
 157 {
 158   assert(_src_region_idx == 0, "not clear");
 159   assert(_partial_obj_size == 0, "not clear");
 160   assert(_destination == NULL, "not clear");
 161   assert(_destination_count == 0, "not clear");
 162   assert(_dest_region_addr == NULL, "not clear");
 163   assert(_first_src_addr == NULL, "not clear");
 164 }
 165 #endif  // #ifdef ASSERT
 166 
 167 
 168 void PSParallelCompact::print_on_error(outputStream* st) {
 169   _mark_bitmap.print_on_error(st);
 170 }
 171 
 172 #ifndef PRODUCT
 173 const char* PSParallelCompact::space_names[] = {
 174   "old ", "eden", "from", "to  "
 175 };
 176 
 177 void PSParallelCompact::print_region_ranges()
 178 {
 179   tty->print_cr("space  bottom     top        end        new_top");
 180   tty->print_cr("------ ---------- ---------- ---------- ----------");
 181 
 182   for (unsigned int id = 0; id < last_space_id; ++id) {
 183     const MutableSpace* space = _space_info[id].space();
 184     tty->print_cr("%u %s "
 185                   SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " "
 186                   SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " ",
 187                   id, space_names[id],
 188                   summary_data().addr_to_region_idx(space->bottom()),
 189                   summary_data().addr_to_region_idx(space->top()),
 190                   summary_data().addr_to_region_idx(space->end()),
 191                   summary_data().addr_to_region_idx(_space_info[id].new_top()));
 192   }
 193 }
 194 
 195 void
 196 print_generic_summary_region(size_t i, const ParallelCompactData::RegionData* c)
 197 {
 198 #define REGION_IDX_FORMAT        SIZE_FORMAT_W(7)
 199 #define REGION_DATA_FORMAT       SIZE_FORMAT_W(5)
 200 
 201   ParallelCompactData& sd = PSParallelCompact::summary_data();
 202   size_t dci = c->destination() ? sd.addr_to_region_idx(c->destination()) : 0;
 203   tty->print_cr(REGION_IDX_FORMAT " " PTR_FORMAT " "
 204                 REGION_IDX_FORMAT " " PTR_FORMAT " "
 205                 REGION_DATA_FORMAT " " REGION_DATA_FORMAT " "
 206                 REGION_DATA_FORMAT " " REGION_IDX_FORMAT " %d",
 207                 i, c->data_location(), dci, c->destination(),
 208                 c->partial_obj_size(), c->live_obj_size(),
 209                 c->data_size(), c->source_region(), c->destination_count());
 210 
 211 #undef  REGION_IDX_FORMAT
 212 #undef  REGION_DATA_FORMAT
 213 }
 214 
 215 void
 216 print_generic_summary_data(ParallelCompactData& summary_data,
 217                            HeapWord* const beg_addr,
 218                            HeapWord* const end_addr)
 219 {
 220   size_t total_words = 0;
 221   size_t i = summary_data.addr_to_region_idx(beg_addr);
 222   const size_t last = summary_data.addr_to_region_idx(end_addr);
 223   HeapWord* pdest = 0;
 224 
 225   while (i <= last) {
 226     ParallelCompactData::RegionData* c = summary_data.region(i);
 227     if (c->data_size() != 0 || c->destination() != pdest) {
 228       print_generic_summary_region(i, c);
 229       total_words += c->data_size();
 230       pdest = c->destination();
 231     }
 232     ++i;
 233   }
 234 
 235   tty->print_cr("summary_data_bytes=" SIZE_FORMAT, total_words * HeapWordSize);
 236 }
 237 
 238 void
 239 print_generic_summary_data(ParallelCompactData& summary_data,
 240                            SpaceInfo* space_info)
 241 {
 242   for (unsigned int id = 0; id < PSParallelCompact::last_space_id; ++id) {
 243     const MutableSpace* space = space_info[id].space();
 244     print_generic_summary_data(summary_data, space->bottom(),
 245                                MAX2(space->top(), space_info[id].new_top()));
 246   }
 247 }
 248 
 249 void
 250 print_initial_summary_region(size_t i,
 251                              const ParallelCompactData::RegionData* c,
 252                              bool newline = true)
 253 {
 254   tty->print(SIZE_FORMAT_W(5) " " PTR_FORMAT " "
 255              SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " "
 256              SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d",
 257              i, c->destination(),
 258              c->partial_obj_size(), c->live_obj_size(),
 259              c->data_size(), c->source_region(), c->destination_count());
 260   if (newline) tty->cr();
 261 }
 262 
 263 void
 264 print_initial_summary_data(ParallelCompactData& summary_data,
 265                            const MutableSpace* space) {
 266   if (space->top() == space->bottom()) {
 267     return;
 268   }
 269 
 270   const size_t region_size = ParallelCompactData::RegionSize;
 271   typedef ParallelCompactData::RegionData RegionData;
 272   HeapWord* const top_aligned_up = summary_data.region_align_up(space->top());
 273   const size_t end_region = summary_data.addr_to_region_idx(top_aligned_up);
 274   const RegionData* c = summary_data.region(end_region - 1);
 275   HeapWord* end_addr = c->destination() + c->data_size();
 276   const size_t live_in_space = pointer_delta(end_addr, space->bottom());
 277 
 278   // Print (and count) the full regions at the beginning of the space.
 279   size_t full_region_count = 0;
 280   size_t i = summary_data.addr_to_region_idx(space->bottom());
 281   while (i < end_region && summary_data.region(i)->data_size() == region_size) {
 282     print_initial_summary_region(i, summary_data.region(i));
 283     ++full_region_count;
 284     ++i;
 285   }
 286 
 287   size_t live_to_right = live_in_space - full_region_count * region_size;
 288 
 289   double max_reclaimed_ratio = 0.0;
 290   size_t max_reclaimed_ratio_region = 0;
 291   size_t max_dead_to_right = 0;
 292   size_t max_live_to_right = 0;
 293 
 294   // Print the 'reclaimed ratio' for regions while there is something live in
 295   // the region or to the right of it.  The remaining regions are empty (and
 296   // uninteresting), and computing the ratio will result in division by 0.
 297   while (i < end_region && live_to_right > 0) {
 298     c = summary_data.region(i);
 299     HeapWord* const region_addr = summary_data.region_to_addr(i);
 300     const size_t used_to_right = pointer_delta(space->top(), region_addr);
 301     const size_t dead_to_right = used_to_right - live_to_right;
 302     const double reclaimed_ratio = double(dead_to_right) / live_to_right;
 303 
 304     if (reclaimed_ratio > max_reclaimed_ratio) {
 305             max_reclaimed_ratio = reclaimed_ratio;
 306             max_reclaimed_ratio_region = i;
 307             max_dead_to_right = dead_to_right;
 308             max_live_to_right = live_to_right;
 309     }
 310 
 311     print_initial_summary_region(i, c, false);
 312     tty->print_cr(" %12.10f " SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10),
 313                   reclaimed_ratio, dead_to_right, live_to_right);
 314 
 315     live_to_right -= c->data_size();
 316     ++i;
 317   }
 318 
 319   // Any remaining regions are empty.  Print one more if there is one.
 320   if (i < end_region) {
 321     print_initial_summary_region(i, summary_data.region(i));
 322   }
 323 
 324   tty->print_cr("max:  " SIZE_FORMAT_W(4) " d2r=" SIZE_FORMAT_W(10) " "
 325                 "l2r=" SIZE_FORMAT_W(10) " max_ratio=%14.12f",
 326                 max_reclaimed_ratio_region, max_dead_to_right,
 327                 max_live_to_right, max_reclaimed_ratio);
 328 }
 329 
 330 void
 331 print_initial_summary_data(ParallelCompactData& summary_data,
 332                            SpaceInfo* space_info) {
 333   unsigned int id = PSParallelCompact::old_space_id;
 334   const MutableSpace* space;
 335   do {
 336     space = space_info[id].space();
 337     print_initial_summary_data(summary_data, space);
 338   } while (++id < PSParallelCompact::eden_space_id);
 339 
 340   do {
 341     space = space_info[id].space();
 342     print_generic_summary_data(summary_data, space->bottom(), space->top());
 343   } while (++id < PSParallelCompact::last_space_id);
 344 }
 345 #endif  // #ifndef PRODUCT
 346 
 347 #ifdef  ASSERT
 348 size_t add_obj_count;
 349 size_t add_obj_size;
 350 size_t mark_bitmap_count;
 351 size_t mark_bitmap_size;
 352 #endif  // #ifdef ASSERT
 353 
 354 ParallelCompactData::ParallelCompactData()
 355 {
 356   _region_start = 0;
 357 
 358   _region_vspace = 0;
 359   _region_data = 0;
 360   _region_count = 0;
 361 }
 362 
 363 bool ParallelCompactData::initialize(MemRegion covered_region)
 364 {
 365   _region_start = covered_region.start();
 366   const size_t region_size = covered_region.word_size();
 367   DEBUG_ONLY(_region_end = _region_start + region_size;)
 368 
 369   assert(region_align_down(_region_start) == _region_start,
 370          "region start not aligned");
 371   assert((region_size & RegionSizeOffsetMask) == 0,
 372          "region size not a multiple of RegionSize");
 373 
 374   bool result = initialize_region_data(region_size);
 375 
 376   return result;
 377 }
 378 
 379 PSVirtualSpace*
 380 ParallelCompactData::create_vspace(size_t count, size_t element_size)
 381 {
 382   const size_t raw_bytes = count * element_size;
 383   const size_t page_sz = os::page_size_for_region(raw_bytes, raw_bytes, 10);
 384   const size_t granularity = os::vm_allocation_granularity();
 385   const size_t bytes = align_size_up(raw_bytes, MAX2(page_sz, granularity));
 386 
 387   const size_t rs_align = page_sz == (size_t) os::vm_page_size() ? 0 :
 388     MAX2(page_sz, granularity);
 389   ReservedSpace rs(bytes, rs_align, rs_align > 0);
 390   os::trace_page_sizes("par compact", raw_bytes, raw_bytes, page_sz, rs.base(),
 391                        rs.size());
 392 
 393   MemTracker::record_virtual_memory_type((address)rs.base(), mtGC);
 394 
 395   PSVirtualSpace* vspace = new PSVirtualSpace(rs, page_sz);
 396   if (vspace != 0) {
 397     if (vspace->expand_by(bytes)) {
 398       return vspace;
 399     }
 400     delete vspace;
 401     // Release memory reserved in the space.
 402     rs.release();
 403   }
 404 
 405   return 0;
 406 }
 407 
 408 bool ParallelCompactData::initialize_region_data(size_t region_size)
 409 {
 410   const size_t count = (region_size + RegionSizeOffsetMask) >> Log2RegionSize;
 411   _region_vspace = create_vspace(count, sizeof(RegionData));
 412   if (_region_vspace != 0) {
 413     _region_data = (RegionData*)_region_vspace->reserved_low_addr();
 414     _region_count = count;
 415     return true;
 416   }
 417   return false;
 418 }
 419 
 420 void ParallelCompactData::clear()
 421 {
 422   memset(_region_data, 0, _region_vspace->committed_size());
 423 }
 424 
 425 void ParallelCompactData::clear_range(size_t beg_region, size_t end_region) {
 426   assert(beg_region <= _region_count, "beg_region out of range");
 427   assert(end_region <= _region_count, "end_region out of range");
 428 
 429   const size_t region_cnt = end_region - beg_region;
 430   memset(_region_data + beg_region, 0, region_cnt * sizeof(RegionData));
 431 }
 432 
 433 HeapWord* ParallelCompactData::partial_obj_end(size_t region_idx) const
 434 {
 435   const RegionData* cur_cp = region(region_idx);
 436   const RegionData* const end_cp = region(region_count() - 1);
 437 
 438   HeapWord* result = region_to_addr(region_idx);
 439   if (cur_cp < end_cp) {
 440     do {
 441       result += cur_cp->partial_obj_size();
 442     } while (cur_cp->partial_obj_size() == RegionSize && ++cur_cp < end_cp);
 443   }
 444   return result;
 445 }
 446 
 447 void ParallelCompactData::add_obj(HeapWord* addr, size_t len)
 448 {
 449   const size_t obj_ofs = pointer_delta(addr, _region_start);
 450   const size_t beg_region = obj_ofs >> Log2RegionSize;
 451   const size_t end_region = (obj_ofs + len - 1) >> Log2RegionSize;
 452 
 453   DEBUG_ONLY(Atomic::inc_ptr(&add_obj_count);)
 454   DEBUG_ONLY(Atomic::add_ptr(len, &add_obj_size);)
 455 
 456   if (beg_region == end_region) {
 457     // All in one region.
 458     _region_data[beg_region].add_live_obj(len);
 459     return;
 460   }
 461 
 462   // First region.
 463   const size_t beg_ofs = region_offset(addr);
 464   _region_data[beg_region].add_live_obj(RegionSize - beg_ofs);
 465 
 466   Klass* klass = ((oop)addr)->klass();
 467   // Middle regions--completely spanned by this object.
 468   for (size_t region = beg_region + 1; region < end_region; ++region) {
 469     _region_data[region].set_partial_obj_size(RegionSize);
 470     _region_data[region].set_partial_obj_addr(addr);
 471   }
 472 
 473   // Last region.
 474   const size_t end_ofs = region_offset(addr + len - 1);
 475   _region_data[end_region].set_partial_obj_size(end_ofs + 1);
 476   _region_data[end_region].set_partial_obj_addr(addr);
 477 }
 478 
 479 void
 480 ParallelCompactData::summarize_dense_prefix(HeapWord* beg, HeapWord* end)
 481 {
 482   assert(region_offset(beg) == 0, "not RegionSize aligned");
 483   assert(region_offset(end) == 0, "not RegionSize aligned");
 484 
 485   size_t cur_region = addr_to_region_idx(beg);
 486   const size_t end_region = addr_to_region_idx(end);
 487   HeapWord* addr = beg;
 488   while (cur_region < end_region) {
 489     _region_data[cur_region].set_destination(addr);
 490     _region_data[cur_region].set_destination_count(0);
 491     _region_data[cur_region].set_source_region(cur_region);
 492     _region_data[cur_region].set_data_location(addr);
 493 
 494     // Update live_obj_size so the region appears completely full.
 495     size_t live_size = RegionSize - _region_data[cur_region].partial_obj_size();
 496     _region_data[cur_region].set_live_obj_size(live_size);
 497 
 498     ++cur_region;
 499     addr += RegionSize;
 500   }
 501 }
 502 
 503 // Find the point at which a space can be split and, if necessary, record the
 504 // split point.
 505 //
 506 // If the current src region (which overflowed the destination space) doesn't
 507 // have a partial object, the split point is at the beginning of the current src
 508 // region (an "easy" split, no extra bookkeeping required).
 509 //
 510 // If the current src region has a partial object, the split point is in the
 511 // region where that partial object starts (call it the split_region).  If
 512 // split_region has a partial object, then the split point is just after that
 513 // partial object (a "hard" split where we have to record the split data and
 514 // zero the partial_obj_size field).  With a "hard" split, we know that the
 515 // partial_obj ends within split_region because the partial object that caused
 516 // the overflow starts in split_region.  If split_region doesn't have a partial
 517 // obj, then the split is at the beginning of split_region (another "easy"
 518 // split).
 519 HeapWord*
 520 ParallelCompactData::summarize_split_space(size_t src_region,
 521                                            SplitInfo& split_info,
 522                                            HeapWord* destination,
 523                                            HeapWord* target_end,
 524                                            HeapWord** target_next)
 525 {
 526   assert(destination <= target_end, "sanity");
 527   assert(destination + _region_data[src_region].data_size() > target_end,
 528     "region should not fit into target space");
 529   assert(is_region_aligned(target_end), "sanity");
 530 
 531   size_t split_region = src_region;
 532   HeapWord* split_destination = destination;
 533   size_t partial_obj_size = _region_data[src_region].partial_obj_size();
 534 
 535   if (destination + partial_obj_size > target_end) {
 536     // The split point is just after the partial object (if any) in the
 537     // src_region that contains the start of the object that overflowed the
 538     // destination space.
 539     //
 540     // Find the start of the "overflow" object and set split_region to the
 541     // region containing it.
 542     HeapWord* const overflow_obj = _region_data[src_region].partial_obj_addr();
 543     split_region = addr_to_region_idx(overflow_obj);
 544 
 545     // Clear the source_region field of all destination regions whose first word
 546     // came from data after the split point (a non-null source_region field
 547     // implies a region must be filled).
 548     //
 549     // An alternative to the simple loop below:  clear during post_compact(),
 550     // which uses memcpy instead of individual stores, and is easy to
 551     // parallelize.  (The downside is that it clears the entire RegionData
 552     // object as opposed to just one field.)
 553     //
 554     // post_compact() would have to clear the summary data up to the highest
 555     // address that was written during the summary phase, which would be
 556     //
 557     //         max(top, max(new_top, clear_top))
 558     //
 559     // where clear_top is a new field in SpaceInfo.  Would have to set clear_top
 560     // to target_end.
 561     const RegionData* const sr = region(split_region);
 562     const size_t beg_idx =
 563       addr_to_region_idx(region_align_up(sr->destination() +
 564                                          sr->partial_obj_size()));
 565     const size_t end_idx = addr_to_region_idx(target_end);
 566 
 567     if (TraceParallelOldGCSummaryPhase) {
 568         gclog_or_tty->print_cr("split:  clearing source_region field in ["
 569                                SIZE_FORMAT ", " SIZE_FORMAT ")",
 570                                beg_idx, end_idx);
 571     }
 572     for (size_t idx = beg_idx; idx < end_idx; ++idx) {
 573       _region_data[idx].set_source_region(0);
 574     }
 575 
 576     // Set split_destination and partial_obj_size to reflect the split region.
 577     split_destination = sr->destination();
 578     partial_obj_size = sr->partial_obj_size();
 579   }
 580 
 581   // The split is recorded only if a partial object extends onto the region.
 582   if (partial_obj_size != 0) {
 583     _region_data[split_region].set_partial_obj_size(0);
 584     split_info.record(split_region, partial_obj_size, split_destination);
 585   }
 586 
 587   // Setup the continuation addresses.
 588   *target_next = split_destination + partial_obj_size;
 589   HeapWord* const source_next = region_to_addr(split_region) + partial_obj_size;
 590 
 591   if (TraceParallelOldGCSummaryPhase) {
 592     const char * split_type = partial_obj_size == 0 ? "easy" : "hard";
 593     gclog_or_tty->print_cr("%s split:  src=" PTR_FORMAT " src_c=" SIZE_FORMAT
 594                            " pos=" SIZE_FORMAT,
 595                            split_type, source_next, split_region,
 596                            partial_obj_size);
 597     gclog_or_tty->print_cr("%s split:  dst=" PTR_FORMAT " dst_c=" SIZE_FORMAT
 598                            " tn=" PTR_FORMAT,
 599                            split_type, split_destination,
 600                            addr_to_region_idx(split_destination),
 601                            *target_next);
 602 
 603     if (partial_obj_size != 0) {
 604       HeapWord* const po_beg = split_info.destination();
 605       HeapWord* const po_end = po_beg + split_info.partial_obj_size();
 606       gclog_or_tty->print_cr("%s split:  "
 607                              "po_beg=" PTR_FORMAT " " SIZE_FORMAT " "
 608                              "po_end=" PTR_FORMAT " " SIZE_FORMAT,
 609                              split_type,
 610                              po_beg, addr_to_region_idx(po_beg),
 611                              po_end, addr_to_region_idx(po_end));
 612     }
 613   }
 614 
 615   return source_next;
 616 }
 617 
 618 bool ParallelCompactData::summarize(SplitInfo& split_info,
 619                                     HeapWord* source_beg, HeapWord* source_end,
 620                                     HeapWord** source_next,
 621                                     HeapWord* target_beg, HeapWord* target_end,
 622                                     HeapWord** target_next)
 623 {
 624   if (TraceParallelOldGCSummaryPhase) {
 625     HeapWord* const source_next_val = source_next == NULL ? NULL : *source_next;
 626     tty->print_cr("sb=" PTR_FORMAT " se=" PTR_FORMAT " sn=" PTR_FORMAT
 627                   "tb=" PTR_FORMAT " te=" PTR_FORMAT " tn=" PTR_FORMAT,
 628                   source_beg, source_end, source_next_val,
 629                   target_beg, target_end, *target_next);
 630   }
 631 
 632   size_t cur_region = addr_to_region_idx(source_beg);
 633   const size_t end_region = addr_to_region_idx(region_align_up(source_end));
 634 
 635   HeapWord *dest_addr = target_beg;
 636   while (cur_region < end_region) {
 637     // The destination must be set even if the region has no data.
 638     _region_data[cur_region].set_destination(dest_addr);
 639 
 640     size_t words = _region_data[cur_region].data_size();
 641     if (words > 0) {
 642       // If cur_region does not fit entirely into the target space, find a point
 643       // at which the source space can be 'split' so that part is copied to the
 644       // target space and the rest is copied elsewhere.
 645       if (dest_addr + words > target_end) {
 646         assert(source_next != NULL, "source_next is NULL when splitting");
 647         *source_next = summarize_split_space(cur_region, split_info, dest_addr,
 648                                              target_end, target_next);
 649         return false;
 650       }
 651 
 652       // Compute the destination_count for cur_region, and if necessary, update
 653       // source_region for a destination region.  The source_region field is
 654       // updated if cur_region is the first (left-most) region to be copied to a
 655       // destination region.
 656       //
 657       // The destination_count calculation is a bit subtle.  A region that has
 658       // data that compacts into itself does not count itself as a destination.
 659       // This maintains the invariant that a zero count means the region is
 660       // available and can be claimed and then filled.
 661       uint destination_count = 0;
 662       if (split_info.is_split(cur_region)) {
 663         // The current region has been split:  the partial object will be copied
 664         // to one destination space and the remaining data will be copied to
 665         // another destination space.  Adjust the initial destination_count and,
 666         // if necessary, set the source_region field if the partial object will
 667         // cross a destination region boundary.
 668         destination_count = split_info.destination_count();
 669         if (destination_count == 2) {
 670           size_t dest_idx = addr_to_region_idx(split_info.dest_region_addr());
 671           _region_data[dest_idx].set_source_region(cur_region);
 672         }
 673       }
 674 
 675       HeapWord* const last_addr = dest_addr + words - 1;
 676       const size_t dest_region_1 = addr_to_region_idx(dest_addr);
 677       const size_t dest_region_2 = addr_to_region_idx(last_addr);
 678 
 679       // Initially assume that the destination regions will be the same and
 680       // adjust the value below if necessary.  Under this assumption, if
 681       // cur_region == dest_region_2, then cur_region will be compacted
 682       // completely into itself.
 683       destination_count += cur_region == dest_region_2 ? 0 : 1;
 684       if (dest_region_1 != dest_region_2) {
 685         // Destination regions differ; adjust destination_count.
 686         destination_count += 1;
 687         // Data from cur_region will be copied to the start of dest_region_2.
 688         _region_data[dest_region_2].set_source_region(cur_region);
 689       } else if (region_offset(dest_addr) == 0) {
 690         // Data from cur_region will be copied to the start of the destination
 691         // region.
 692         _region_data[dest_region_1].set_source_region(cur_region);
 693       }
 694 
 695       _region_data[cur_region].set_destination_count(destination_count);
 696       _region_data[cur_region].set_data_location(region_to_addr(cur_region));
 697       dest_addr += words;
 698     }
 699 
 700     ++cur_region;
 701   }
 702 
 703   *target_next = dest_addr;
 704   return true;
 705 }
 706 
 707 HeapWord* ParallelCompactData::calc_new_pointer(HeapWord* addr) {
 708   assert(addr != NULL, "Should detect NULL oop earlier");
 709   assert(PSParallelCompact::gc_heap()->is_in(addr), "addr not in heap");
 710 #ifdef ASSERT
 711   if (PSParallelCompact::mark_bitmap()->is_unmarked(addr)) {
 712     gclog_or_tty->print_cr("calc_new_pointer:: addr " PTR_FORMAT, addr);
 713   }
 714 #endif
 715   assert(PSParallelCompact::mark_bitmap()->is_marked(addr), "obj not marked");
 716 
 717   // Region covering the object.
 718   size_t region_index = addr_to_region_idx(addr);
 719   const RegionData* const region_ptr = region(region_index);
 720   HeapWord* const region_addr = region_align_down(addr);
 721 
 722   assert(addr < region_addr + RegionSize, "Region does not cover object");
 723   assert(addr_to_region_ptr(region_addr) == region_ptr, "sanity check");
 724 
 725   HeapWord* result = region_ptr->destination();
 726 
 727   // If all the data in the region is live, then the new location of the object
 728   // can be calculated from the destination of the region plus the offset of the
 729   // object in the region.
 730   if (region_ptr->data_size() == RegionSize) {
 731     result += pointer_delta(addr, region_addr);
 732     DEBUG_ONLY(PSParallelCompact::check_new_location(addr, result);)
 733     return result;
 734   }
 735 
 736   // The new location of the object is
 737   //    region destination +
 738   //    size of the partial object extending onto the region +
 739   //    sizes of the live objects in the Region that are to the left of addr
 740   const size_t partial_obj_size = region_ptr->partial_obj_size();
 741   HeapWord* const search_start = region_addr + partial_obj_size;
 742 
 743   const ParMarkBitMap* bitmap = PSParallelCompact::mark_bitmap();
 744   size_t live_to_left = bitmap->live_words_in_range(search_start, oop(addr));
 745 
 746   result += partial_obj_size + live_to_left;
 747   DEBUG_ONLY(PSParallelCompact::check_new_location(addr, result);)
 748   return result;
 749 }
 750 
 751 #ifdef  ASSERT
 752 void ParallelCompactData::verify_clear(const PSVirtualSpace* vspace)
 753 {
 754   const size_t* const beg = (const size_t*)vspace->committed_low_addr();
 755   const size_t* const end = (const size_t*)vspace->committed_high_addr();
 756   for (const size_t* p = beg; p < end; ++p) {
 757     assert(*p == 0, "not zero");
 758   }
 759 }
 760 
 761 void ParallelCompactData::verify_clear()
 762 {
 763   verify_clear(_region_vspace);
 764 }
 765 #endif  // #ifdef ASSERT
 766 
 767 #ifdef NOT_PRODUCT
 768 ParallelCompactData::RegionData* debug_region(size_t region_index) {
 769   ParallelCompactData& sd = PSParallelCompact::summary_data();
 770   return sd.region(region_index);
 771 }
 772 #endif
 773 
 774 elapsedTimer        PSParallelCompact::_accumulated_time;
 775 unsigned int        PSParallelCompact::_total_invocations = 0;
 776 unsigned int        PSParallelCompact::_maximum_compaction_gc_num = 0;
 777 jlong               PSParallelCompact::_time_of_last_gc = 0;
 778 CollectorCounters*  PSParallelCompact::_counters = NULL;
 779 ParMarkBitMap       PSParallelCompact::_mark_bitmap;
 780 ParallelCompactData PSParallelCompact::_summary_data;
 781 
 782 PSParallelCompact::IsAliveClosure PSParallelCompact::_is_alive_closure;
 783 
 784 void PSParallelCompact::IsAliveClosure::do_object(oop p)   { ShouldNotReachHere(); }
 785 bool PSParallelCompact::IsAliveClosure::do_object_b(oop p) { return mark_bitmap()->is_marked(p); }
 786 
 787 void PSParallelCompact::KeepAliveClosure::do_oop(oop* p)       { PSParallelCompact::KeepAliveClosure::do_oop_work(p); }
 788 void PSParallelCompact::KeepAliveClosure::do_oop(narrowOop* p) { PSParallelCompact::KeepAliveClosure::do_oop_work(p); }
 789 
 790 PSParallelCompact::AdjustPointerClosure PSParallelCompact::_adjust_pointer_closure;
 791 PSParallelCompact::AdjustKlassClosure PSParallelCompact::_adjust_klass_closure;
 792 
 793 void PSParallelCompact::AdjustPointerClosure::do_oop(oop* p)       { adjust_pointer(p); }
 794 void PSParallelCompact::AdjustPointerClosure::do_oop(narrowOop* p) { adjust_pointer(p); }
 795 
 796 void PSParallelCompact::FollowStackClosure::do_void() { _compaction_manager->follow_marking_stacks(); }
 797 
 798 void PSParallelCompact::MarkAndPushClosure::do_oop(oop* p)       {
 799   mark_and_push(_compaction_manager, p);
 800 }
 801 void PSParallelCompact::MarkAndPushClosure::do_oop(narrowOop* p) { mark_and_push(_compaction_manager, p); }
 802 
 803 void PSParallelCompact::FollowKlassClosure::do_klass(Klass* klass) {
 804   klass->oops_do(_mark_and_push_closure);
 805 }
 806 void PSParallelCompact::AdjustKlassClosure::do_klass(Klass* klass) {
 807   klass->oops_do(&PSParallelCompact::_adjust_pointer_closure);
 808 }
 809 
 810 void PSParallelCompact::post_initialize() {
 811   ParallelScavengeHeap* heap = gc_heap();
 812   assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
 813 
 814   MemRegion mr = heap->reserved_region();
 815   _ref_processor =
 816     new ReferenceProcessor(mr,            // span
 817                            ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing
 818                            (int) ParallelGCThreads, // mt processing degree
 819                            true,          // mt discovery
 820                            (int) ParallelGCThreads, // mt discovery degree
 821                            true,          // atomic_discovery
 822                            &_is_alive_closure, // non-header is alive closure
 823                            false);        // write barrier for next field updates
 824   _counters = new CollectorCounters("PSParallelCompact", 1);
 825 
 826   // Initialize static fields in ParCompactionManager.
 827   ParCompactionManager::initialize(mark_bitmap());
 828 }
 829 
 830 bool PSParallelCompact::initialize() {
 831   ParallelScavengeHeap* heap = gc_heap();
 832   assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
 833   MemRegion mr = heap->reserved_region();
 834 
 835   // Was the old gen get allocated successfully?
 836   if (!heap->old_gen()->is_allocated()) {
 837     return false;
 838   }
 839 
 840   initialize_space_info();
 841   initialize_dead_wood_limiter();
 842 
 843   if (!_mark_bitmap.initialize(mr)) {
 844     vm_shutdown_during_initialization("Unable to allocate bit map for "
 845       "parallel garbage collection for the requested heap size.");
 846     return false;
 847   }
 848 
 849   if (!_summary_data.initialize(mr)) {
 850     vm_shutdown_during_initialization("Unable to allocate tables for "
 851       "parallel garbage collection for the requested heap size.");
 852     return false;
 853   }
 854 
 855   return true;
 856 }
 857 
 858 void PSParallelCompact::initialize_space_info()
 859 {
 860   memset(&_space_info, 0, sizeof(_space_info));
 861 
 862   ParallelScavengeHeap* heap = gc_heap();
 863   PSYoungGen* young_gen = heap->young_gen();
 864 
 865   _space_info[old_space_id].set_space(heap->old_gen()->object_space());
 866   _space_info[eden_space_id].set_space(young_gen->eden_space());
 867   _space_info[from_space_id].set_space(young_gen->from_space());
 868   _space_info[to_space_id].set_space(young_gen->to_space());
 869 
 870   _space_info[old_space_id].set_start_array(heap->old_gen()->start_array());
 871 }
 872 
 873 void PSParallelCompact::initialize_dead_wood_limiter()
 874 {
 875   const size_t max = 100;
 876   _dwl_mean = double(MIN2(ParallelOldDeadWoodLimiterMean, max)) / 100.0;
 877   _dwl_std_dev = double(MIN2(ParallelOldDeadWoodLimiterStdDev, max)) / 100.0;
 878   _dwl_first_term = 1.0 / (sqrt(2.0 * M_PI) * _dwl_std_dev);
 879   DEBUG_ONLY(_dwl_initialized = true;)
 880   _dwl_adjustment = normal_distribution(1.0);
 881 }
 882 
 883 // Simple class for storing info about the heap at the start of GC, to be used
 884 // after GC for comparison/printing.
 885 class PreGCValues {
 886 public:
 887   PreGCValues() { }
 888   PreGCValues(ParallelScavengeHeap* heap) { fill(heap); }
 889 
 890   void fill(ParallelScavengeHeap* heap) {
 891     _heap_used      = heap->used();
 892     _young_gen_used = heap->young_gen()->used_in_bytes();
 893     _old_gen_used   = heap->old_gen()->used_in_bytes();
 894     _metadata_used  = MetaspaceAux::allocated_used_bytes();
 895   };
 896 
 897   size_t heap_used() const      { return _heap_used; }
 898   size_t young_gen_used() const { return _young_gen_used; }
 899   size_t old_gen_used() const   { return _old_gen_used; }
 900   size_t metadata_used() const  { return _metadata_used; }
 901 
 902 private:
 903   size_t _heap_used;
 904   size_t _young_gen_used;
 905   size_t _old_gen_used;
 906   size_t _metadata_used;
 907 };
 908 
 909 void
 910 PSParallelCompact::clear_data_covering_space(SpaceId id)
 911 {
 912   // At this point, top is the value before GC, new_top() is the value that will
 913   // be set at the end of GC.  The marking bitmap is cleared to top; nothing
 914   // should be marked above top.  The summary data is cleared to the larger of
 915   // top & new_top.
 916   MutableSpace* const space = _space_info[id].space();
 917   HeapWord* const bot = space->bottom();
 918   HeapWord* const top = space->top();
 919   HeapWord* const max_top = MAX2(top, _space_info[id].new_top());
 920 
 921   const idx_t beg_bit = _mark_bitmap.addr_to_bit(bot);
 922   const idx_t end_bit = BitMap::word_align_up(_mark_bitmap.addr_to_bit(top));
 923   _mark_bitmap.clear_range(beg_bit, end_bit);
 924 
 925   const size_t beg_region = _summary_data.addr_to_region_idx(bot);
 926   const size_t end_region =
 927     _summary_data.addr_to_region_idx(_summary_data.region_align_up(max_top));
 928   _summary_data.clear_range(beg_region, end_region);
 929 
 930   // Clear the data used to 'split' regions.
 931   SplitInfo& split_info = _space_info[id].split_info();
 932   if (split_info.is_valid()) {
 933     split_info.clear();
 934   }
 935   DEBUG_ONLY(split_info.verify_clear();)
 936 }
 937 
 938 void PSParallelCompact::pre_compact(PreGCValues* pre_gc_values)
 939 {
 940   // Update the from & to space pointers in space_info, since they are swapped
 941   // at each young gen gc.  Do the update unconditionally (even though a
 942   // promotion failure does not swap spaces) because an unknown number of minor
 943   // collections will have swapped the spaces an unknown number of times.
 944   TraceTime tm("pre compact", print_phases(), true, gclog_or_tty);
 945   ParallelScavengeHeap* heap = gc_heap();
 946   _space_info[from_space_id].set_space(heap->young_gen()->from_space());
 947   _space_info[to_space_id].set_space(heap->young_gen()->to_space());
 948 
 949   pre_gc_values->fill(heap);
 950 
 951   DEBUG_ONLY(add_obj_count = add_obj_size = 0;)
 952   DEBUG_ONLY(mark_bitmap_count = mark_bitmap_size = 0;)
 953 
 954   // Increment the invocation count
 955   heap->increment_total_collections(true);
 956 
 957   // We need to track unique mark sweep invocations as well.
 958   _total_invocations++;
 959 
 960   heap->print_heap_before_gc();
 961 
 962   // Fill in TLABs
 963   heap->accumulate_statistics_all_tlabs();
 964   heap->ensure_parsability(true);  // retire TLABs
 965 
 966   if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
 967     HandleMark hm;  // Discard invalid handles created during verification
 968     Universe::verify(" VerifyBeforeGC:");
 969   }
 970 
 971   // Verify object start arrays
 972   if (VerifyObjectStartArray &&
 973       VerifyBeforeGC) {
 974     heap->old_gen()->verify_object_start_array();
 975   }
 976 
 977   DEBUG_ONLY(mark_bitmap()->verify_clear();)
 978   DEBUG_ONLY(summary_data().verify_clear();)
 979 
 980   // Have worker threads release resources the next time they run a task.
 981   gc_task_manager()->release_all_resources();
 982 }
 983 
 984 void PSParallelCompact::post_compact()
 985 {
 986   TraceTime tm("post compact", print_phases(), true, gclog_or_tty);
 987 
 988   for (unsigned int id = old_space_id; id < last_space_id; ++id) {
 989     // Clear the marking bitmap, summary data and split info.
 990     clear_data_covering_space(SpaceId(id));
 991     // Update top().  Must be done after clearing the bitmap and summary data.
 992     _space_info[id].publish_new_top();
 993   }
 994 
 995   MutableSpace* const eden_space = _space_info[eden_space_id].space();
 996   MutableSpace* const from_space = _space_info[from_space_id].space();
 997   MutableSpace* const to_space   = _space_info[to_space_id].space();
 998 
 999   ParallelScavengeHeap* heap = gc_heap();
1000   bool eden_empty = eden_space->is_empty();
1001   if (!eden_empty) {
1002     eden_empty = absorb_live_data_from_eden(heap->size_policy(),
1003                                             heap->young_gen(), heap->old_gen());
1004   }
1005 
1006   // Update heap occupancy information which is used as input to the soft ref
1007   // clearing policy at the next gc.
1008   Universe::update_heap_info_at_gc();
1009 
1010   bool young_gen_empty = eden_empty && from_space->is_empty() &&
1011     to_space->is_empty();
1012 
1013   BarrierSet* bs = heap->barrier_set();
1014   if (bs->is_a(BarrierSet::ModRef)) {
1015     ModRefBarrierSet* modBS = (ModRefBarrierSet*)bs;
1016     MemRegion old_mr = heap->old_gen()->reserved();
1017 
1018     if (young_gen_empty) {
1019       modBS->clear(MemRegion(old_mr.start(), old_mr.end()));
1020     } else {
1021       modBS->invalidate(MemRegion(old_mr.start(), old_mr.end()));
1022     }
1023   }
1024 
1025   // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1026   ClassLoaderDataGraph::purge();
1027   MetaspaceAux::verify_metrics();
1028 
1029   Threads::gc_epilogue();
1030   CodeCache::gc_epilogue();
1031   JvmtiExport::gc_epilogue();
1032 
1033   COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1034 
1035   ref_processor()->enqueue_discovered_references(NULL);
1036 
1037   if (ZapUnusedHeapArea) {
1038     heap->gen_mangle_unused_area();
1039   }
1040 
1041   // Update time of last GC
1042   reset_millis_since_last_gc();
1043 }
1044 
1045 HeapWord*
1046 PSParallelCompact::compute_dense_prefix_via_density(const SpaceId id,
1047                                                     bool maximum_compaction)
1048 {
1049   const size_t region_size = ParallelCompactData::RegionSize;
1050   const ParallelCompactData& sd = summary_data();
1051 
1052   const MutableSpace* const space = _space_info[id].space();
1053   HeapWord* const top_aligned_up = sd.region_align_up(space->top());
1054   const RegionData* const beg_cp = sd.addr_to_region_ptr(space->bottom());
1055   const RegionData* const end_cp = sd.addr_to_region_ptr(top_aligned_up);
1056 
1057   // Skip full regions at the beginning of the space--they are necessarily part
1058   // of the dense prefix.
1059   size_t full_count = 0;
1060   const RegionData* cp;
1061   for (cp = beg_cp; cp < end_cp && cp->data_size() == region_size; ++cp) {
1062     ++full_count;
1063   }
1064 
1065   assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");
1066   const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;
1067   const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval;
1068   if (maximum_compaction || cp == end_cp || interval_ended) {
1069     _maximum_compaction_gc_num = total_invocations();
1070     return sd.region_to_addr(cp);
1071   }
1072 
1073   HeapWord* const new_top = _space_info[id].new_top();
1074   const size_t space_live = pointer_delta(new_top, space->bottom());
1075   const size_t space_used = space->used_in_words();
1076   const size_t space_capacity = space->capacity_in_words();
1077 
1078   const double cur_density = double(space_live) / space_capacity;
1079   const double deadwood_density =
1080     (1.0 - cur_density) * (1.0 - cur_density) * cur_density * cur_density;
1081   const size_t deadwood_goal = size_t(space_capacity * deadwood_density);
1082 
1083   if (TraceParallelOldGCDensePrefix) {
1084     tty->print_cr("cur_dens=%5.3f dw_dens=%5.3f dw_goal=" SIZE_FORMAT,
1085                   cur_density, deadwood_density, deadwood_goal);
1086     tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " "
1087                   "space_cap=" SIZE_FORMAT,
1088                   space_live, space_used,
1089                   space_capacity);
1090   }
1091 
1092   // XXX - Use binary search?
1093   HeapWord* dense_prefix = sd.region_to_addr(cp);
1094   const RegionData* full_cp = cp;
1095   const RegionData* const top_cp = sd.addr_to_region_ptr(space->top() - 1);
1096   while (cp < end_cp) {
1097     HeapWord* region_destination = cp->destination();
1098     const size_t cur_deadwood = pointer_delta(dense_prefix, region_destination);
1099     if (TraceParallelOldGCDensePrefix && Verbose) {
1100       tty->print_cr("c#=" SIZE_FORMAT_W(4) " dst=" PTR_FORMAT " "
1101                     "dp=" SIZE_FORMAT_W(8) " " "cdw=" SIZE_FORMAT_W(8),
1102                     sd.region(cp), region_destination,
1103                     dense_prefix, cur_deadwood);
1104     }
1105 
1106     if (cur_deadwood >= deadwood_goal) {
1107       // Found the region that has the correct amount of deadwood to the left.
1108       // This typically occurs after crossing a fairly sparse set of regions, so
1109       // iterate backwards over those sparse regions, looking for the region
1110       // that has the lowest density of live objects 'to the right.'
1111       size_t space_to_left = sd.region(cp) * region_size;
1112       size_t live_to_left = space_to_left - cur_deadwood;
1113       size_t space_to_right = space_capacity - space_to_left;
1114       size_t live_to_right = space_live - live_to_left;
1115       double density_to_right = double(live_to_right) / space_to_right;
1116       while (cp > full_cp) {
1117         --cp;
1118         const size_t prev_region_live_to_right = live_to_right -
1119           cp->data_size();
1120         const size_t prev_region_space_to_right = space_to_right + region_size;
1121         double prev_region_density_to_right =
1122           double(prev_region_live_to_right) / prev_region_space_to_right;
1123         if (density_to_right <= prev_region_density_to_right) {
1124           return dense_prefix;
1125         }
1126         if (TraceParallelOldGCDensePrefix && Verbose) {
1127           tty->print_cr("backing up from c=" SIZE_FORMAT_W(4) " d2r=%10.8f "
1128                         "pc_d2r=%10.8f", sd.region(cp), density_to_right,
1129                         prev_region_density_to_right);
1130         }
1131         dense_prefix -= region_size;
1132         live_to_right = prev_region_live_to_right;
1133         space_to_right = prev_region_space_to_right;
1134         density_to_right = prev_region_density_to_right;
1135       }
1136       return dense_prefix;
1137     }
1138 
1139     dense_prefix += region_size;
1140     ++cp;
1141   }
1142 
1143   return dense_prefix;
1144 }
1145 
1146 #ifndef PRODUCT
1147 void PSParallelCompact::print_dense_prefix_stats(const char* const algorithm,
1148                                                  const SpaceId id,
1149                                                  const bool maximum_compaction,
1150                                                  HeapWord* const addr)
1151 {
1152   const size_t region_idx = summary_data().addr_to_region_idx(addr);
1153   RegionData* const cp = summary_data().region(region_idx);
1154   const MutableSpace* const space = _space_info[id].space();
1155   HeapWord* const new_top = _space_info[id].new_top();
1156 
1157   const size_t space_live = pointer_delta(new_top, space->bottom());
1158   const size_t dead_to_left = pointer_delta(addr, cp->destination());
1159   const size_t space_cap = space->capacity_in_words();
1160   const double dead_to_left_pct = double(dead_to_left) / space_cap;
1161   const size_t live_to_right = new_top - cp->destination();
1162   const size_t dead_to_right = space->top() - addr - live_to_right;
1163 
1164   tty->print_cr("%s=" PTR_FORMAT " dpc=" SIZE_FORMAT_W(5) " "
1165                 "spl=" SIZE_FORMAT " "
1166                 "d2l=" SIZE_FORMAT " d2l%%=%6.4f "
1167                 "d2r=" SIZE_FORMAT " l2r=" SIZE_FORMAT
1168                 " ratio=%10.8f",
1169                 algorithm, addr, region_idx,
1170                 space_live,
1171                 dead_to_left, dead_to_left_pct,
1172                 dead_to_right, live_to_right,
1173                 double(dead_to_right) / live_to_right);
1174 }
1175 #endif  // #ifndef PRODUCT
1176 
1177 // Return a fraction indicating how much of the generation can be treated as
1178 // "dead wood" (i.e., not reclaimed).  The function uses a normal distribution
1179 // based on the density of live objects in the generation to determine a limit,
1180 // which is then adjusted so the return value is min_percent when the density is
1181 // 1.
1182 //
1183 // The following table shows some return values for a different values of the
1184 // standard deviation (ParallelOldDeadWoodLimiterStdDev); the mean is 0.5 and
1185 // min_percent is 1.
1186 //
1187 //                          fraction allowed as dead wood
1188 //         -----------------------------------------------------------------
1189 // density std_dev=70 std_dev=75 std_dev=80 std_dev=85 std_dev=90 std_dev=95
1190 // ------- ---------- ---------- ---------- ---------- ---------- ----------
1191 // 0.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
1192 // 0.05000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
1193 // 0.10000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
1194 // 0.15000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
1195 // 0.20000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
1196 // 0.25000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
1197 // 0.30000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
1198 // 0.35000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
1199 // 0.40000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
1200 // 0.45000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
1201 // 0.50000 0.13832410 0.11599237 0.09847664 0.08456518 0.07338887 0.06431510
1202 // 0.55000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
1203 // 0.60000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
1204 // 0.65000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
1205 // 0.70000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
1206 // 0.75000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
1207 // 0.80000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
1208 // 0.85000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
1209 // 0.90000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
1210 // 0.95000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
1211 // 1.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
1212 
1213 double PSParallelCompact::dead_wood_limiter(double density, size_t min_percent)
1214 {
1215   assert(_dwl_initialized, "uninitialized");
1216 
1217   // The raw limit is the value of the normal distribution at x = density.
1218   const double raw_limit = normal_distribution(density);
1219 
1220   // Adjust the raw limit so it becomes the minimum when the density is 1.
1221   //
1222   // First subtract the adjustment value (which is simply the precomputed value
1223   // normal_distribution(1.0)); this yields a value of 0 when the density is 1.
1224   // Then add the minimum value, so the minimum is returned when the density is
1225   // 1.  Finally, prevent negative values, which occur when the mean is not 0.5.
1226   const double min = double(min_percent) / 100.0;
1227   const double limit = raw_limit - _dwl_adjustment + min;
1228   return MAX2(limit, 0.0);
1229 }
1230 
1231 ParallelCompactData::RegionData*
1232 PSParallelCompact::first_dead_space_region(const RegionData* beg,
1233                                            const RegionData* end)
1234 {
1235   const size_t region_size = ParallelCompactData::RegionSize;
1236   ParallelCompactData& sd = summary_data();
1237   size_t left = sd.region(beg);
1238   size_t right = end > beg ? sd.region(end) - 1 : left;
1239 
1240   // Binary search.
1241   while (left < right) {
1242     // Equivalent to (left + right) / 2, but does not overflow.
1243     const size_t middle = left + (right - left) / 2;
1244     RegionData* const middle_ptr = sd.region(middle);
1245     HeapWord* const dest = middle_ptr->destination();
1246     HeapWord* const addr = sd.region_to_addr(middle);
1247     assert(dest != NULL, "sanity");
1248     assert(dest <= addr, "must move left");
1249 
1250     if (middle > left && dest < addr) {
1251       right = middle - 1;
1252     } else if (middle < right && middle_ptr->data_size() == region_size) {
1253       left = middle + 1;
1254     } else {
1255       return middle_ptr;
1256     }
1257   }
1258   return sd.region(left);
1259 }
1260 
1261 ParallelCompactData::RegionData*
1262 PSParallelCompact::dead_wood_limit_region(const RegionData* beg,
1263                                           const RegionData* end,
1264                                           size_t dead_words)
1265 {
1266   ParallelCompactData& sd = summary_data();
1267   size_t left = sd.region(beg);
1268   size_t right = end > beg ? sd.region(end) - 1 : left;
1269 
1270   // Binary search.
1271   while (left < right) {
1272     // Equivalent to (left + right) / 2, but does not overflow.
1273     const size_t middle = left + (right - left) / 2;
1274     RegionData* const middle_ptr = sd.region(middle);
1275     HeapWord* const dest = middle_ptr->destination();
1276     HeapWord* const addr = sd.region_to_addr(middle);
1277     assert(dest != NULL, "sanity");
1278     assert(dest <= addr, "must move left");
1279 
1280     const size_t dead_to_left = pointer_delta(addr, dest);
1281     if (middle > left && dead_to_left > dead_words) {
1282       right = middle - 1;
1283     } else if (middle < right && dead_to_left < dead_words) {
1284       left = middle + 1;
1285     } else {
1286       return middle_ptr;
1287     }
1288   }
1289   return sd.region(left);
1290 }
1291 
1292 // The result is valid during the summary phase, after the initial summarization
1293 // of each space into itself, and before final summarization.
1294 inline double
1295 PSParallelCompact::reclaimed_ratio(const RegionData* const cp,
1296                                    HeapWord* const bottom,
1297                                    HeapWord* const top,
1298                                    HeapWord* const new_top)
1299 {
1300   ParallelCompactData& sd = summary_data();
1301 
1302   assert(cp != NULL, "sanity");
1303   assert(bottom != NULL, "sanity");
1304   assert(top != NULL, "sanity");
1305   assert(new_top != NULL, "sanity");
1306   assert(top >= new_top, "summary data problem?");
1307   assert(new_top > bottom, "space is empty; should not be here");
1308   assert(new_top >= cp->destination(), "sanity");
1309   assert(top >= sd.region_to_addr(cp), "sanity");
1310 
1311   HeapWord* const destination = cp->destination();
1312   const size_t dense_prefix_live  = pointer_delta(destination, bottom);
1313   const size_t compacted_region_live = pointer_delta(new_top, destination);
1314   const size_t compacted_region_used = pointer_delta(top,
1315                                                      sd.region_to_addr(cp));
1316   const size_t reclaimable = compacted_region_used - compacted_region_live;
1317 
1318   const double divisor = dense_prefix_live + 1.25 * compacted_region_live;
1319   return double(reclaimable) / divisor;
1320 }
1321 
1322 // Return the address of the end of the dense prefix, a.k.a. the start of the
1323 // compacted region.  The address is always on a region boundary.
1324 //
1325 // Completely full regions at the left are skipped, since no compaction can
1326 // occur in those regions.  Then the maximum amount of dead wood to allow is
1327 // computed, based on the density (amount live / capacity) of the generation;
1328 // the region with approximately that amount of dead space to the left is
1329 // identified as the limit region.  Regions between the last completely full
1330 // region and the limit region are scanned and the one that has the best
1331 // (maximum) reclaimed_ratio() is selected.
1332 HeapWord*
1333 PSParallelCompact::compute_dense_prefix(const SpaceId id,
1334                                         bool maximum_compaction)
1335 {
1336   if (ParallelOldGCSplitALot) {
1337     if (_space_info[id].dense_prefix() != _space_info[id].space()->bottom()) {
1338       // The value was chosen to provoke splitting a young gen space; use it.
1339       return _space_info[id].dense_prefix();
1340     }
1341   }
1342 
1343   const size_t region_size = ParallelCompactData::RegionSize;
1344   const ParallelCompactData& sd = summary_data();
1345 
1346   const MutableSpace* const space = _space_info[id].space();
1347   HeapWord* const top = space->top();
1348   HeapWord* const top_aligned_up = sd.region_align_up(top);
1349   HeapWord* const new_top = _space_info[id].new_top();
1350   HeapWord* const new_top_aligned_up = sd.region_align_up(new_top);
1351   HeapWord* const bottom = space->bottom();
1352   const RegionData* const beg_cp = sd.addr_to_region_ptr(bottom);
1353   const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
1354   const RegionData* const new_top_cp =
1355     sd.addr_to_region_ptr(new_top_aligned_up);
1356 
1357   // Skip full regions at the beginning of the space--they are necessarily part
1358   // of the dense prefix.
1359   const RegionData* const full_cp = first_dead_space_region(beg_cp, new_top_cp);
1360   assert(full_cp->destination() == sd.region_to_addr(full_cp) ||
1361          space->is_empty(), "no dead space allowed to the left");
1362   assert(full_cp->data_size() < region_size || full_cp == new_top_cp - 1,
1363          "region must have dead space");
1364 
1365   // The gc number is saved whenever a maximum compaction is done, and used to
1366   // determine when the maximum compaction interval has expired.  This avoids
1367   // successive max compactions for different reasons.
1368   assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");
1369   const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;
1370   const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval ||
1371     total_invocations() == HeapFirstMaximumCompactionCount;
1372   if (maximum_compaction || full_cp == top_cp || interval_ended) {
1373     _maximum_compaction_gc_num = total_invocations();
1374     return sd.region_to_addr(full_cp);
1375   }
1376 
1377   const size_t space_live = pointer_delta(new_top, bottom);
1378   const size_t space_used = space->used_in_words();
1379   const size_t space_capacity = space->capacity_in_words();
1380 
1381   const double density = double(space_live) / double(space_capacity);
1382   const size_t min_percent_free = MarkSweepDeadRatio;
1383   const double limiter = dead_wood_limiter(density, min_percent_free);
1384   const size_t dead_wood_max = space_used - space_live;
1385   const size_t dead_wood_limit = MIN2(size_t(space_capacity * limiter),
1386                                       dead_wood_max);
1387 
1388   if (TraceParallelOldGCDensePrefix) {
1389     tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " "
1390                   "space_cap=" SIZE_FORMAT,
1391                   space_live, space_used,
1392                   space_capacity);
1393     tty->print_cr("dead_wood_limiter(%6.4f, %d)=%6.4f "
1394                   "dead_wood_max=" SIZE_FORMAT " dead_wood_limit=" SIZE_FORMAT,
1395                   density, min_percent_free, limiter,
1396                   dead_wood_max, dead_wood_limit);
1397   }
1398 
1399   // Locate the region with the desired amount of dead space to the left.
1400   const RegionData* const limit_cp =
1401     dead_wood_limit_region(full_cp, top_cp, dead_wood_limit);
1402 
1403   // Scan from the first region with dead space to the limit region and find the
1404   // one with the best (largest) reclaimed ratio.
1405   double best_ratio = 0.0;
1406   const RegionData* best_cp = full_cp;
1407   for (const RegionData* cp = full_cp; cp < limit_cp; ++cp) {
1408     double tmp_ratio = reclaimed_ratio(cp, bottom, top, new_top);
1409     if (tmp_ratio > best_ratio) {
1410       best_cp = cp;
1411       best_ratio = tmp_ratio;
1412     }
1413   }
1414 
1415 #if     0
1416   // Something to consider:  if the region with the best ratio is 'close to' the
1417   // first region w/free space, choose the first region with free space
1418   // ("first-free").  The first-free region is usually near the start of the
1419   // heap, which means we are copying most of the heap already, so copy a bit
1420   // more to get complete compaction.
1421   if (pointer_delta(best_cp, full_cp, sizeof(RegionData)) < 4) {
1422     _maximum_compaction_gc_num = total_invocations();
1423     best_cp = full_cp;
1424   }
1425 #endif  // #if 0
1426 
1427   return sd.region_to_addr(best_cp);
1428 }
1429 
1430 #ifndef PRODUCT
1431 void
1432 PSParallelCompact::fill_with_live_objects(SpaceId id, HeapWord* const start,
1433                                           size_t words)
1434 {
1435   if (TraceParallelOldGCSummaryPhase) {
1436     tty->print_cr("fill_with_live_objects [" PTR_FORMAT " " PTR_FORMAT ") "
1437                   SIZE_FORMAT, start, start + words, words);
1438   }
1439 
1440   ObjectStartArray* const start_array = _space_info[id].start_array();
1441   CollectedHeap::fill_with_objects(start, words);
1442   for (HeapWord* p = start; p < start + words; p += oop(p)->size()) {
1443     _mark_bitmap.mark_obj(p, words);
1444     _summary_data.add_obj(p, words);
1445     start_array->allocate_block(p);
1446   }
1447 }
1448 
1449 void
1450 PSParallelCompact::summarize_new_objects(SpaceId id, HeapWord* start)
1451 {
1452   ParallelCompactData& sd = summary_data();
1453   MutableSpace* space = _space_info[id].space();
1454 
1455   // Find the source and destination start addresses.
1456   HeapWord* const src_addr = sd.region_align_down(start);
1457   HeapWord* dst_addr;
1458   if (src_addr < start) {
1459     dst_addr = sd.addr_to_region_ptr(src_addr)->destination();
1460   } else if (src_addr > space->bottom()) {
1461     // The start (the original top() value) is aligned to a region boundary so
1462     // the associated region does not have a destination.  Compute the
1463     // destination from the previous region.
1464     RegionData* const cp = sd.addr_to_region_ptr(src_addr) - 1;
1465     dst_addr = cp->destination() + cp->data_size();
1466   } else {
1467     // Filling the entire space.
1468     dst_addr = space->bottom();
1469   }
1470   assert(dst_addr != NULL, "sanity");
1471 
1472   // Update the summary data.
1473   bool result = _summary_data.summarize(_space_info[id].split_info(),
1474                                         src_addr, space->top(), NULL,
1475                                         dst_addr, space->end(),
1476                                         _space_info[id].new_top_addr());
1477   assert(result, "should not fail:  bad filler object size");
1478 }
1479 
1480 void
1481 PSParallelCompact::provoke_split_fill_survivor(SpaceId id)
1482 {
1483   if (total_invocations() % (ParallelOldGCSplitInterval * 3) != 0) {
1484     return;
1485   }
1486 
1487   MutableSpace* const space = _space_info[id].space();
1488   if (space->is_empty()) {
1489     HeapWord* b = space->bottom();
1490     HeapWord* t = b + space->capacity_in_words() / 2;
1491     space->set_top(t);
1492     if (ZapUnusedHeapArea) {
1493       space->set_top_for_allocations();
1494     }
1495 
1496     size_t min_size = CollectedHeap::min_fill_size();
1497     size_t obj_len = min_size;
1498     while (b + obj_len <= t) {
1499       CollectedHeap::fill_with_object(b, obj_len);
1500       mark_bitmap()->mark_obj(b, obj_len);
1501       summary_data().add_obj(b, obj_len);
1502       b += obj_len;
1503       obj_len = (obj_len & (min_size*3)) + min_size; // 8 16 24 32 8 16 24 32 ...
1504     }
1505     if (b < t) {
1506       // The loop didn't completely fill to t (top); adjust top downward.
1507       space->set_top(b);
1508       if (ZapUnusedHeapArea) {
1509         space->set_top_for_allocations();
1510       }
1511     }
1512 
1513     HeapWord** nta = _space_info[id].new_top_addr();
1514     bool result = summary_data().summarize(_space_info[id].split_info(),
1515                                            space->bottom(), space->top(), NULL,
1516                                            space->bottom(), space->end(), nta);
1517     assert(result, "space must fit into itself");
1518   }
1519 }
1520 
1521 void
1522 PSParallelCompact::provoke_split(bool & max_compaction)
1523 {
1524   if (total_invocations() % ParallelOldGCSplitInterval != 0) {
1525     return;
1526   }
1527 
1528   const size_t region_size = ParallelCompactData::RegionSize;
1529   ParallelCompactData& sd = summary_data();
1530 
1531   MutableSpace* const eden_space = _space_info[eden_space_id].space();
1532   MutableSpace* const from_space = _space_info[from_space_id].space();
1533   const size_t eden_live = pointer_delta(eden_space->top(),
1534                                          _space_info[eden_space_id].new_top());
1535   const size_t from_live = pointer_delta(from_space->top(),
1536                                          _space_info[from_space_id].new_top());
1537 
1538   const size_t min_fill_size = CollectedHeap::min_fill_size();
1539   const size_t eden_free = pointer_delta(eden_space->end(), eden_space->top());
1540   const size_t eden_fillable = eden_free >= min_fill_size ? eden_free : 0;
1541   const size_t from_free = pointer_delta(from_space->end(), from_space->top());
1542   const size_t from_fillable = from_free >= min_fill_size ? from_free : 0;
1543 
1544   // Choose the space to split; need at least 2 regions live (or fillable).
1545   SpaceId id;
1546   MutableSpace* space;
1547   size_t live_words;
1548   size_t fill_words;
1549   if (eden_live + eden_fillable >= region_size * 2) {
1550     id = eden_space_id;
1551     space = eden_space;
1552     live_words = eden_live;
1553     fill_words = eden_fillable;
1554   } else if (from_live + from_fillable >= region_size * 2) {
1555     id = from_space_id;
1556     space = from_space;
1557     live_words = from_live;
1558     fill_words = from_fillable;
1559   } else {
1560     return; // Give up.
1561   }
1562   assert(fill_words == 0 || fill_words >= min_fill_size, "sanity");
1563 
1564   if (live_words < region_size * 2) {
1565     // Fill from top() to end() w/live objects of mixed sizes.
1566     HeapWord* const fill_start = space->top();
1567     live_words += fill_words;
1568 
1569     space->set_top(fill_start + fill_words);
1570     if (ZapUnusedHeapArea) {
1571       space->set_top_for_allocations();
1572     }
1573 
1574     HeapWord* cur_addr = fill_start;
1575     while (fill_words > 0) {
1576       const size_t r = (size_t)os::random() % (region_size / 2) + min_fill_size;
1577       size_t cur_size = MIN2(align_object_size_(r), fill_words);
1578       if (fill_words - cur_size < min_fill_size) {
1579         cur_size = fill_words; // Avoid leaving a fragment too small to fill.
1580       }
1581 
1582       CollectedHeap::fill_with_object(cur_addr, cur_size);
1583       mark_bitmap()->mark_obj(cur_addr, cur_size);
1584       sd.add_obj(cur_addr, cur_size);
1585 
1586       cur_addr += cur_size;
1587       fill_words -= cur_size;
1588     }
1589 
1590     summarize_new_objects(id, fill_start);
1591   }
1592 
1593   max_compaction = false;
1594 
1595   // Manipulate the old gen so that it has room for about half of the live data
1596   // in the target young gen space (live_words / 2).
1597   id = old_space_id;
1598   space = _space_info[id].space();
1599   const size_t free_at_end = space->free_in_words();
1600   const size_t free_target = align_object_size(live_words / 2);
1601   const size_t dead = pointer_delta(space->top(), _space_info[id].new_top());
1602 
1603   if (free_at_end >= free_target + min_fill_size) {
1604     // Fill space above top() and set the dense prefix so everything survives.
1605     HeapWord* const fill_start = space->top();
1606     const size_t fill_size = free_at_end - free_target;
1607     space->set_top(space->top() + fill_size);
1608     if (ZapUnusedHeapArea) {
1609       space->set_top_for_allocations();
1610     }
1611     fill_with_live_objects(id, fill_start, fill_size);
1612     summarize_new_objects(id, fill_start);
1613     _space_info[id].set_dense_prefix(sd.region_align_down(space->top()));
1614   } else if (dead + free_at_end > free_target) {
1615     // Find a dense prefix that makes the right amount of space available.
1616     HeapWord* cur = sd.region_align_down(space->top());
1617     HeapWord* cur_destination = sd.addr_to_region_ptr(cur)->destination();
1618     size_t dead_to_right = pointer_delta(space->end(), cur_destination);
1619     while (dead_to_right < free_target) {
1620       cur -= region_size;
1621       cur_destination = sd.addr_to_region_ptr(cur)->destination();
1622       dead_to_right = pointer_delta(space->end(), cur_destination);
1623     }
1624     _space_info[id].set_dense_prefix(cur);
1625   }
1626 }
1627 #endif // #ifndef PRODUCT
1628 
1629 void PSParallelCompact::summarize_spaces_quick()
1630 {
1631   for (unsigned int i = 0; i < last_space_id; ++i) {
1632     const MutableSpace* space = _space_info[i].space();
1633     HeapWord** nta = _space_info[i].new_top_addr();
1634     bool result = _summary_data.summarize(_space_info[i].split_info(),
1635                                           space->bottom(), space->top(), NULL,
1636                                           space->bottom(), space->end(), nta);
1637     assert(result, "space must fit into itself");
1638     _space_info[i].set_dense_prefix(space->bottom());
1639   }
1640 
1641 #ifndef PRODUCT
1642   if (ParallelOldGCSplitALot) {
1643     provoke_split_fill_survivor(to_space_id);
1644   }
1645 #endif // #ifndef PRODUCT
1646 }
1647 
1648 void PSParallelCompact::fill_dense_prefix_end(SpaceId id)
1649 {
1650   HeapWord* const dense_prefix_end = dense_prefix(id);
1651   const RegionData* region = _summary_data.addr_to_region_ptr(dense_prefix_end);
1652   const idx_t dense_prefix_bit = _mark_bitmap.addr_to_bit(dense_prefix_end);
1653   if (dead_space_crosses_boundary(region, dense_prefix_bit)) {
1654     // Only enough dead space is filled so that any remaining dead space to the
1655     // left is larger than the minimum filler object.  (The remainder is filled
1656     // during the copy/update phase.)
1657     //
1658     // The size of the dead space to the right of the boundary is not a
1659     // concern, since compaction will be able to use whatever space is
1660     // available.
1661     //
1662     // Here '||' is the boundary, 'x' represents a don't care bit and a box
1663     // surrounds the space to be filled with an object.
1664     //
1665     // In the 32-bit VM, each bit represents two 32-bit words:
1666     //                              +---+
1667     // a) beg_bits:  ...  x   x   x | 0 | ||   0   x  x  ...
1668     //    end_bits:  ...  x   x   x | 0 | ||   0   x  x  ...
1669     //                              +---+
1670     //
1671     // In the 64-bit VM, each bit represents one 64-bit word:
1672     //                              +------------+
1673     // b) beg_bits:  ...  x   x   x | 0   ||   0 | x  x  ...
1674     //    end_bits:  ...  x   x   1 | 0   ||   0 | x  x  ...
1675     //                              +------------+
1676     //                          +-------+
1677     // c) beg_bits:  ...  x   x | 0   0 | ||   0   x  x  ...
1678     //    end_bits:  ...  x   1 | 0   0 | ||   0   x  x  ...
1679     //                          +-------+
1680     //                      +-----------+
1681     // d) beg_bits:  ...  x | 0   0   0 | ||   0   x  x  ...
1682     //    end_bits:  ...  1 | 0   0   0 | ||   0   x  x  ...
1683     //                      +-----------+
1684     //                          +-------+
1685     // e) beg_bits:  ...  0   0 | 0   0 | ||   0   x  x  ...
1686     //    end_bits:  ...  0   0 | 0   0 | ||   0   x  x  ...
1687     //                          +-------+
1688 
1689     // Initially assume case a, c or e will apply.
1690     size_t obj_len = CollectedHeap::min_fill_size();
1691     HeapWord* obj_beg = dense_prefix_end - obj_len;
1692 
1693 #ifdef  _LP64
1694     if (MinObjAlignment > 1) { // object alignment > heap word size
1695       // Cases a, c or e.
1696     } else if (_mark_bitmap.is_obj_end(dense_prefix_bit - 2)) {
1697       // Case b above.
1698       obj_beg = dense_prefix_end - 1;
1699     } else if (!_mark_bitmap.is_obj_end(dense_prefix_bit - 3) &&
1700                _mark_bitmap.is_obj_end(dense_prefix_bit - 4)) {
1701       // Case d above.
1702       obj_beg = dense_prefix_end - 3;
1703       obj_len = 3;
1704     }
1705 #endif  // #ifdef _LP64
1706 
1707     CollectedHeap::fill_with_object(obj_beg, obj_len);
1708     _mark_bitmap.mark_obj(obj_beg, obj_len);
1709     _summary_data.add_obj(obj_beg, obj_len);
1710     assert(start_array(id) != NULL, "sanity");
1711     start_array(id)->allocate_block(obj_beg);
1712   }
1713 }
1714 
1715 void
1716 PSParallelCompact::clear_source_region(HeapWord* beg_addr, HeapWord* end_addr)
1717 {
1718   RegionData* const beg_ptr = _summary_data.addr_to_region_ptr(beg_addr);
1719   HeapWord* const end_aligned_up = _summary_data.region_align_up(end_addr);
1720   RegionData* const end_ptr = _summary_data.addr_to_region_ptr(end_aligned_up);
1721   for (RegionData* cur = beg_ptr; cur < end_ptr; ++cur) {
1722     cur->set_source_region(0);
1723   }
1724 }
1725 
1726 void
1727 PSParallelCompact::summarize_space(SpaceId id, bool maximum_compaction)
1728 {
1729   assert(id < last_space_id, "id out of range");
1730   assert(_space_info[id].dense_prefix() == _space_info[id].space()->bottom() ||
1731          ParallelOldGCSplitALot && id == old_space_id,
1732          "should have been reset in summarize_spaces_quick()");
1733 
1734   const MutableSpace* space = _space_info[id].space();
1735   if (_space_info[id].new_top() != space->bottom()) {
1736     HeapWord* dense_prefix_end = compute_dense_prefix(id, maximum_compaction);
1737     _space_info[id].set_dense_prefix(dense_prefix_end);
1738 
1739 #ifndef PRODUCT
1740     if (TraceParallelOldGCDensePrefix) {
1741       print_dense_prefix_stats("ratio", id, maximum_compaction,
1742                                dense_prefix_end);
1743       HeapWord* addr = compute_dense_prefix_via_density(id, maximum_compaction);
1744       print_dense_prefix_stats("density", id, maximum_compaction, addr);
1745     }
1746 #endif  // #ifndef PRODUCT
1747 
1748     // Recompute the summary data, taking into account the dense prefix.  If
1749     // every last byte will be reclaimed, then the existing summary data which
1750     // compacts everything can be left in place.
1751     if (!maximum_compaction && dense_prefix_end != space->bottom()) {
1752       // If dead space crosses the dense prefix boundary, it is (at least
1753       // partially) filled with a dummy object, marked live and added to the
1754       // summary data.  This simplifies the copy/update phase and must be done
1755       // before the final locations of objects are determined, to prevent
1756       // leaving a fragment of dead space that is too small to fill.
1757       fill_dense_prefix_end(id);
1758 
1759       // Compute the destination of each Region, and thus each object.
1760       _summary_data.summarize_dense_prefix(space->bottom(), dense_prefix_end);
1761       _summary_data.summarize(_space_info[id].split_info(),
1762                               dense_prefix_end, space->top(), NULL,
1763                               dense_prefix_end, space->end(),
1764                               _space_info[id].new_top_addr());
1765     }
1766   }
1767 
1768   if (TraceParallelOldGCSummaryPhase) {
1769     const size_t region_size = ParallelCompactData::RegionSize;
1770     HeapWord* const dense_prefix_end = _space_info[id].dense_prefix();
1771     const size_t dp_region = _summary_data.addr_to_region_idx(dense_prefix_end);
1772     const size_t dp_words = pointer_delta(dense_prefix_end, space->bottom());
1773     HeapWord* const new_top = _space_info[id].new_top();
1774     const HeapWord* nt_aligned_up = _summary_data.region_align_up(new_top);
1775     const size_t cr_words = pointer_delta(nt_aligned_up, dense_prefix_end);
1776     tty->print_cr("id=%d cap=" SIZE_FORMAT " dp=" PTR_FORMAT " "
1777                   "dp_region=" SIZE_FORMAT " " "dp_count=" SIZE_FORMAT " "
1778                   "cr_count=" SIZE_FORMAT " " "nt=" PTR_FORMAT,
1779                   id, space->capacity_in_words(), dense_prefix_end,
1780                   dp_region, dp_words / region_size,
1781                   cr_words / region_size, new_top);
1782   }
1783 }
1784 
1785 #ifndef PRODUCT
1786 void PSParallelCompact::summary_phase_msg(SpaceId dst_space_id,
1787                                           HeapWord* dst_beg, HeapWord* dst_end,
1788                                           SpaceId src_space_id,
1789                                           HeapWord* src_beg, HeapWord* src_end)
1790 {
1791   if (TraceParallelOldGCSummaryPhase) {
1792     tty->print_cr("summarizing %d [%s] into %d [%s]:  "
1793                   "src=" PTR_FORMAT "-" PTR_FORMAT " "
1794                   SIZE_FORMAT "-" SIZE_FORMAT " "
1795                   "dst=" PTR_FORMAT "-" PTR_FORMAT " "
1796                   SIZE_FORMAT "-" SIZE_FORMAT,
1797                   src_space_id, space_names[src_space_id],
1798                   dst_space_id, space_names[dst_space_id],
1799                   src_beg, src_end,
1800                   _summary_data.addr_to_region_idx(src_beg),
1801                   _summary_data.addr_to_region_idx(src_end),
1802                   dst_beg, dst_end,
1803                   _summary_data.addr_to_region_idx(dst_beg),
1804                   _summary_data.addr_to_region_idx(dst_end));
1805   }
1806 }
1807 #endif  // #ifndef PRODUCT
1808 
1809 void PSParallelCompact::summary_phase(ParCompactionManager* cm,
1810                                       bool maximum_compaction)
1811 {
1812   TraceTime tm("summary phase", print_phases(), true, gclog_or_tty);
1813   // trace("2");
1814 
1815 #ifdef  ASSERT
1816   if (TraceParallelOldGCMarkingPhase) {
1817     tty->print_cr("add_obj_count=" SIZE_FORMAT " "
1818                   "add_obj_bytes=" SIZE_FORMAT,
1819                   add_obj_count, add_obj_size * HeapWordSize);
1820     tty->print_cr("mark_bitmap_count=" SIZE_FORMAT " "
1821                   "mark_bitmap_bytes=" SIZE_FORMAT,
1822                   mark_bitmap_count, mark_bitmap_size * HeapWordSize);
1823   }
1824 #endif  // #ifdef ASSERT
1825 
1826   // Quick summarization of each space into itself, to see how much is live.
1827   summarize_spaces_quick();
1828 
1829   if (TraceParallelOldGCSummaryPhase) {
1830     tty->print_cr("summary_phase:  after summarizing each space to self");
1831     Universe::print();
1832     NOT_PRODUCT(print_region_ranges());
1833     if (Verbose) {
1834       NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info));
1835     }
1836   }
1837 
1838   // The amount of live data that will end up in old space (assuming it fits).
1839   size_t old_space_total_live = 0;
1840   for (unsigned int id = old_space_id; id < last_space_id; ++id) {
1841     old_space_total_live += pointer_delta(_space_info[id].new_top(),
1842                                           _space_info[id].space()->bottom());
1843   }
1844 
1845   MutableSpace* const old_space = _space_info[old_space_id].space();
1846   const size_t old_capacity = old_space->capacity_in_words();
1847   if (old_space_total_live > old_capacity) {
1848     // XXX - should also try to expand
1849     maximum_compaction = true;
1850   }
1851 #ifndef PRODUCT
1852   if (ParallelOldGCSplitALot && old_space_total_live < old_capacity) {
1853     provoke_split(maximum_compaction);
1854   }
1855 #endif // #ifndef PRODUCT
1856 
1857   // Old generations.
1858   summarize_space(old_space_id, maximum_compaction);
1859 
1860   // Summarize the remaining spaces in the young gen.  The initial target space
1861   // is the old gen.  If a space does not fit entirely into the target, then the
1862   // remainder is compacted into the space itself and that space becomes the new
1863   // target.
1864   SpaceId dst_space_id = old_space_id;
1865   HeapWord* dst_space_end = old_space->end();
1866   HeapWord** new_top_addr = _space_info[dst_space_id].new_top_addr();
1867   for (unsigned int id = eden_space_id; id < last_space_id; ++id) {
1868     const MutableSpace* space = _space_info[id].space();
1869     const size_t live = pointer_delta(_space_info[id].new_top(),
1870                                       space->bottom());
1871     const size_t available = pointer_delta(dst_space_end, *new_top_addr);
1872 
1873     NOT_PRODUCT(summary_phase_msg(dst_space_id, *new_top_addr, dst_space_end,
1874                                   SpaceId(id), space->bottom(), space->top());)
1875     if (live > 0 && live <= available) {
1876       // All the live data will fit.
1877       bool done = _summary_data.summarize(_space_info[id].split_info(),
1878                                           space->bottom(), space->top(),
1879                                           NULL,
1880                                           *new_top_addr, dst_space_end,
1881                                           new_top_addr);
1882       assert(done, "space must fit into old gen");
1883 
1884       // Reset the new_top value for the space.
1885       _space_info[id].set_new_top(space->bottom());
1886     } else if (live > 0) {
1887       // Attempt to fit part of the source space into the target space.
1888       HeapWord* next_src_addr = NULL;
1889       bool done = _summary_data.summarize(_space_info[id].split_info(),
1890                                           space->bottom(), space->top(),
1891                                           &next_src_addr,
1892                                           *new_top_addr, dst_space_end,
1893                                           new_top_addr);
1894       assert(!done, "space should not fit into old gen");
1895       assert(next_src_addr != NULL, "sanity");
1896 
1897       // The source space becomes the new target, so the remainder is compacted
1898       // within the space itself.
1899       dst_space_id = SpaceId(id);
1900       dst_space_end = space->end();
1901       new_top_addr = _space_info[id].new_top_addr();
1902       NOT_PRODUCT(summary_phase_msg(dst_space_id,
1903                                     space->bottom(), dst_space_end,
1904                                     SpaceId(id), next_src_addr, space->top());)
1905       done = _summary_data.summarize(_space_info[id].split_info(),
1906                                      next_src_addr, space->top(),
1907                                      NULL,
1908                                      space->bottom(), dst_space_end,
1909                                      new_top_addr);
1910       assert(done, "space must fit when compacted into itself");
1911       assert(*new_top_addr <= space->top(), "usage should not grow");
1912     }
1913   }
1914 
1915   if (TraceParallelOldGCSummaryPhase) {
1916     tty->print_cr("summary_phase:  after final summarization");
1917     Universe::print();
1918     NOT_PRODUCT(print_region_ranges());
1919     if (Verbose) {
1920       NOT_PRODUCT(print_generic_summary_data(_summary_data, _space_info));
1921     }
1922   }
1923 }
1924 
1925 // This method should contain all heap-specific policy for invoking a full
1926 // collection.  invoke_no_policy() will only attempt to compact the heap; it
1927 // will do nothing further.  If we need to bail out for policy reasons, scavenge
1928 // before full gc, or any other specialized behavior, it needs to be added here.
1929 //
1930 // Note that this method should only be called from the vm_thread while at a
1931 // safepoint.
1932 //
1933 // Note that the all_soft_refs_clear flag in the collector policy
1934 // may be true because this method can be called without intervening
1935 // activity.  For example when the heap space is tight and full measure
1936 // are being taken to free space.
1937 void PSParallelCompact::invoke(bool maximum_heap_compaction) {
1938   assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
1939   assert(Thread::current() == (Thread*)VMThread::vm_thread(),
1940          "should be in vm thread");
1941 
1942   ParallelScavengeHeap* heap = gc_heap();
1943   GCCause::Cause gc_cause = heap->gc_cause();
1944   assert(!heap->is_gc_active(), "not reentrant");
1945 
1946   PSAdaptiveSizePolicy* policy = heap->size_policy();
1947   IsGCActiveMark mark;
1948 
1949   if (ScavengeBeforeFullGC) {
1950     PSScavenge::invoke_no_policy();
1951   }
1952 
1953   const bool clear_all_soft_refs =
1954     heap->collector_policy()->should_clear_all_soft_refs();
1955 
1956   PSParallelCompact::invoke_no_policy(clear_all_soft_refs ||
1957                                       maximum_heap_compaction);
1958 }
1959 
1960 bool ParallelCompactData::region_contains(size_t region_index, HeapWord* addr) {
1961   size_t addr_region_index = addr_to_region_idx(addr);
1962   return region_index == addr_region_index;
1963 }
1964 
1965 // This method contains no policy. You should probably
1966 // be calling invoke() instead.
1967 bool PSParallelCompact::invoke_no_policy(bool maximum_heap_compaction) {
1968   assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
1969   assert(ref_processor() != NULL, "Sanity");
1970 
1971   if (GC_locker::check_active_before_gc()) {
1972     return false;
1973   }
1974 
1975   TimeStamp marking_start;
1976   TimeStamp compaction_start;
1977   TimeStamp collection_exit;
1978 
1979   ParallelScavengeHeap* heap = gc_heap();
1980   GCCause::Cause gc_cause = heap->gc_cause();
1981   PSYoungGen* young_gen = heap->young_gen();
1982   PSOldGen* old_gen = heap->old_gen();
1983   PSAdaptiveSizePolicy* size_policy = heap->size_policy();
1984 
1985   // The scope of casr should end after code that can change
1986   // CollectorPolicy::_should_clear_all_soft_refs.
1987   ClearedAllSoftRefs casr(maximum_heap_compaction,
1988                           heap->collector_policy());
1989 
1990   if (ZapUnusedHeapArea) {
1991     // Save information needed to minimize mangling
1992     heap->record_gen_tops_before_GC();
1993   }
1994 
1995   heap->pre_full_gc_dump();
1996 
1997   _print_phases = PrintGCDetails && PrintParallelOldGCPhaseTimes;
1998 
1999   // Make sure data structures are sane, make the heap parsable, and do other
2000   // miscellaneous bookkeeping.
2001   PreGCValues pre_gc_values;
2002   pre_compact(&pre_gc_values);
2003 
2004   // Get the compaction manager reserved for the VM thread.
2005   ParCompactionManager* const vmthread_cm =
2006     ParCompactionManager::manager_array(gc_task_manager()->workers());
2007 
2008   // Place after pre_compact() where the number of invocations is incremented.
2009   AdaptiveSizePolicyOutput(size_policy, heap->total_collections());
2010 
2011   {
2012     ResourceMark rm;
2013     HandleMark hm;
2014 
2015     // Set the number of GC threads to be used in this collection
2016     gc_task_manager()->set_active_gang();
2017     gc_task_manager()->task_idle_workers();
2018     heap->set_par_threads(gc_task_manager()->active_workers());
2019 
2020     gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
2021     TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
2022     TraceTime t1(GCCauseString("Full GC", gc_cause), PrintGC, !PrintGCDetails, gclog_or_tty);
2023     TraceCollectorStats tcs(counters());
2024     TraceMemoryManagerStats tms(true /* Full GC */,gc_cause);
2025 
2026     if (TraceGen1Time) accumulated_time()->start();
2027 
2028     // Let the size policy know we're starting
2029     size_policy->major_collection_begin();
2030 
2031     CodeCache::gc_prologue();
2032     Threads::gc_prologue();
2033 
2034     COMPILER2_PRESENT(DerivedPointerTable::clear());
2035 
2036     ref_processor()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
2037     ref_processor()->setup_policy(maximum_heap_compaction);
2038 
2039     bool marked_for_unloading = false;
2040 
2041     marking_start.update();
2042     marking_phase(vmthread_cm, maximum_heap_compaction);
2043 
2044     bool max_on_system_gc = UseMaximumCompactionOnSystemGC
2045       && gc_cause == GCCause::_java_lang_system_gc;
2046     summary_phase(vmthread_cm, maximum_heap_compaction || max_on_system_gc);
2047 
2048     COMPILER2_PRESENT(assert(DerivedPointerTable::is_active(), "Sanity"));
2049     COMPILER2_PRESENT(DerivedPointerTable::set_active(false));
2050 
2051     // adjust_roots() updates Universe::_intArrayKlassObj which is
2052     // needed by the compaction for filling holes in the dense prefix.
2053     adjust_roots();
2054 
2055     compaction_start.update();
2056     compact();
2057 
2058     // Reset the mark bitmap, summary data, and do other bookkeeping.  Must be
2059     // done before resizing.
2060     post_compact();
2061 
2062     // Let the size policy know we're done
2063     size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause);
2064 
2065     if (UseAdaptiveSizePolicy) {
2066       if (PrintAdaptiveSizePolicy) {
2067         gclog_or_tty->print("AdaptiveSizeStart: ");
2068         gclog_or_tty->stamp();
2069         gclog_or_tty->print_cr(" collection: %d ",
2070                        heap->total_collections());
2071         if (Verbose) {
2072           gclog_or_tty->print("old_gen_capacity: %d young_gen_capacity: %d",
2073             old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes());
2074         }
2075       }
2076 
2077       // Don't check if the size_policy is ready here.  Let
2078       // the size_policy check that internally.
2079       if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&
2080           ((gc_cause != GCCause::_java_lang_system_gc) ||
2081             UseAdaptiveSizePolicyWithSystemGC)) {
2082         // Calculate optimal free space amounts
2083         assert(young_gen->max_size() >
2084           young_gen->from_space()->capacity_in_bytes() +
2085           young_gen->to_space()->capacity_in_bytes(),
2086           "Sizes of space in young gen are out-of-bounds");
2087         size_t max_eden_size = young_gen->max_size() -
2088           young_gen->from_space()->capacity_in_bytes() -
2089           young_gen->to_space()->capacity_in_bytes();
2090         size_policy->compute_generation_free_space(
2091                               young_gen->used_in_bytes(),
2092                               young_gen->eden_space()->used_in_bytes(),
2093                               old_gen->used_in_bytes(),
2094                               young_gen->eden_space()->capacity_in_bytes(),
2095                               old_gen->max_gen_size(),
2096                               max_eden_size,
2097                               true /* full gc*/,
2098                               gc_cause,
2099                               heap->collector_policy());
2100 
2101         heap->resize_old_gen(
2102           size_policy->calculated_old_free_size_in_bytes());
2103 
2104         // Don't resize the young generation at an major collection.  A
2105         // desired young generation size may have been calculated but
2106         // resizing the young generation complicates the code because the
2107         // resizing of the old generation may have moved the boundary
2108         // between the young generation and the old generation.  Let the
2109         // young generation resizing happen at the minor collections.
2110       }
2111       if (PrintAdaptiveSizePolicy) {
2112         gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ",
2113                        heap->total_collections());
2114       }
2115     }
2116 
2117     if (UsePerfData) {
2118       PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters();
2119       counters->update_counters();
2120       counters->update_old_capacity(old_gen->capacity_in_bytes());
2121       counters->update_young_capacity(young_gen->capacity_in_bytes());
2122     }
2123 
2124     heap->resize_all_tlabs();
2125 
2126     // Resize the metaspace capactiy after a collection
2127     MetaspaceGC::compute_new_size();
2128 
2129     if (TraceGen1Time) accumulated_time()->stop();
2130 
2131     if (PrintGC) {
2132       if (PrintGCDetails) {
2133         // No GC timestamp here.  This is after GC so it would be confusing.
2134         young_gen->print_used_change(pre_gc_values.young_gen_used());
2135         old_gen->print_used_change(pre_gc_values.old_gen_used());
2136         heap->print_heap_change(pre_gc_values.heap_used());
2137         MetaspaceAux::print_metaspace_change(pre_gc_values.metadata_used());
2138       } else {
2139         heap->print_heap_change(pre_gc_values.heap_used());
2140       }
2141     }
2142 
2143     // Track memory usage and detect low memory
2144     MemoryService::track_memory_usage();
2145     heap->update_counters();
2146     gc_task_manager()->release_idle_workers();
2147   }
2148 
2149 #ifdef ASSERT
2150   for (size_t i = 0; i < ParallelGCThreads + 1; ++i) {
2151     ParCompactionManager* const cm =
2152       ParCompactionManager::manager_array(int(i));
2153     assert(cm->marking_stack()->is_empty(),       "should be empty");
2154     assert(ParCompactionManager::region_list(int(i))->is_empty(), "should be empty");
2155   }
2156 #endif // ASSERT
2157 
2158   if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
2159     HandleMark hm;  // Discard invalid handles created during verification
2160     Universe::verify(" VerifyAfterGC:");
2161   }
2162 
2163   // Re-verify object start arrays
2164   if (VerifyObjectStartArray &&
2165       VerifyAfterGC) {
2166     old_gen->verify_object_start_array();
2167   }
2168 
2169   if (ZapUnusedHeapArea) {
2170     old_gen->object_space()->check_mangled_unused_area_complete();
2171   }
2172 
2173   NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
2174 
2175   collection_exit.update();
2176 
2177   heap->print_heap_after_gc();
2178   if (PrintGCTaskTimeStamps) {
2179     gclog_or_tty->print_cr("VM-Thread " INT64_FORMAT " " INT64_FORMAT " "
2180                            INT64_FORMAT,
2181                            marking_start.ticks(), compaction_start.ticks(),
2182                            collection_exit.ticks());
2183     gc_task_manager()->print_task_time_stamps();
2184   }
2185 
2186   heap->post_full_gc_dump();
2187 
2188 #ifdef TRACESPINNING
2189   ParallelTaskTerminator::print_termination_counts();
2190 #endif
2191 
2192   return true;
2193 }
2194 
2195 bool PSParallelCompact::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
2196                                              PSYoungGen* young_gen,
2197                                              PSOldGen* old_gen) {
2198   MutableSpace* const eden_space = young_gen->eden_space();
2199   assert(!eden_space->is_empty(), "eden must be non-empty");
2200   assert(young_gen->virtual_space()->alignment() ==
2201          old_gen->virtual_space()->alignment(), "alignments do not match");
2202 
2203   if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) {
2204     return false;
2205   }
2206 
2207   // Both generations must be completely committed.
2208   if (young_gen->virtual_space()->uncommitted_size() != 0) {
2209     return false;
2210   }
2211   if (old_gen->virtual_space()->uncommitted_size() != 0) {
2212     return false;
2213   }
2214 
2215   // Figure out how much to take from eden.  Include the average amount promoted
2216   // in the total; otherwise the next young gen GC will simply bail out to a
2217   // full GC.
2218   const size_t alignment = old_gen->virtual_space()->alignment();
2219   const size_t eden_used = eden_space->used_in_bytes();
2220   const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average();
2221   const size_t absorb_size = align_size_up(eden_used + promoted, alignment);
2222   const size_t eden_capacity = eden_space->capacity_in_bytes();
2223 
2224   if (absorb_size >= eden_capacity) {
2225     return false; // Must leave some space in eden.
2226   }
2227 
2228   const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size;
2229   if (new_young_size < young_gen->min_gen_size()) {
2230     return false; // Respect young gen minimum size.
2231   }
2232 
2233   if (TraceAdaptiveGCBoundary && Verbose) {
2234     gclog_or_tty->print(" absorbing " SIZE_FORMAT "K:  "
2235                         "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K "
2236                         "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K "
2237                         "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ",
2238                         absorb_size / K,
2239                         eden_capacity / K, (eden_capacity - absorb_size) / K,
2240                         young_gen->from_space()->used_in_bytes() / K,
2241                         young_gen->to_space()->used_in_bytes() / K,
2242                         young_gen->capacity_in_bytes() / K, new_young_size / K);
2243   }
2244 
2245   // Fill the unused part of the old gen.
2246   MutableSpace* const old_space = old_gen->object_space();
2247   HeapWord* const unused_start = old_space->top();
2248   size_t const unused_words = pointer_delta(old_space->end(), unused_start);
2249 
2250   if (unused_words > 0) {
2251     if (unused_words < CollectedHeap::min_fill_size()) {
2252       return false;  // If the old gen cannot be filled, must give up.
2253     }
2254     CollectedHeap::fill_with_objects(unused_start, unused_words);
2255   }
2256 
2257   // Take the live data from eden and set both top and end in the old gen to
2258   // eden top.  (Need to set end because reset_after_change() mangles the region
2259   // from end to virtual_space->high() in debug builds).
2260   HeapWord* const new_top = eden_space->top();
2261   old_gen->virtual_space()->expand_into(young_gen->virtual_space(),
2262                                         absorb_size);
2263   young_gen->reset_after_change();
2264   old_space->set_top(new_top);
2265   old_space->set_end(new_top);
2266   old_gen->reset_after_change();
2267 
2268   // Update the object start array for the filler object and the data from eden.
2269   ObjectStartArray* const start_array = old_gen->start_array();
2270   for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) {
2271     start_array->allocate_block(p);
2272   }
2273 
2274   // Could update the promoted average here, but it is not typically updated at
2275   // full GCs and the value to use is unclear.  Something like
2276   //
2277   // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc.
2278 
2279   size_policy->set_bytes_absorbed_from_eden(absorb_size);
2280   return true;
2281 }
2282 
2283 GCTaskManager* const PSParallelCompact::gc_task_manager() {
2284   assert(ParallelScavengeHeap::gc_task_manager() != NULL,
2285     "shouldn't return NULL");
2286   return ParallelScavengeHeap::gc_task_manager();
2287 }
2288 
2289 void PSParallelCompact::marking_phase(ParCompactionManager* cm,
2290                                       bool maximum_heap_compaction) {
2291   // Recursively traverse all live objects and mark them
2292   TraceTime tm("marking phase", print_phases(), true, gclog_or_tty);
2293 
2294   ParallelScavengeHeap* heap = gc_heap();
2295   uint parallel_gc_threads = heap->gc_task_manager()->workers();
2296   uint active_gc_threads = heap->gc_task_manager()->active_workers();
2297   TaskQueueSetSuper* qset = ParCompactionManager::region_array();
2298   ParallelTaskTerminator terminator(active_gc_threads, qset);
2299 
2300   PSParallelCompact::MarkAndPushClosure mark_and_push_closure(cm);
2301   PSParallelCompact::FollowStackClosure follow_stack_closure(cm);
2302 
2303   // Need new claim bits before marking starts.
2304   ClassLoaderDataGraph::clear_claimed_marks();
2305 
2306   {
2307     TraceTime tm_m("par mark", print_phases(), true, gclog_or_tty);
2308     ParallelScavengeHeap::ParStrongRootsScope psrs;
2309 
2310     GCTaskQueue* q = GCTaskQueue::create();
2311 
2312     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::universe));
2313     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jni_handles));
2314     // We scan the thread roots in parallel
2315     Threads::create_thread_roots_marking_tasks(q);
2316     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::object_synchronizer));
2317     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::flat_profiler));
2318     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::management));
2319     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::system_dictionary));
2320     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jvmti));
2321     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::code_cache));
2322 
2323     if (active_gc_threads > 1) {
2324       for (uint j = 0; j < active_gc_threads; j++) {
2325         q->enqueue(new StealMarkingTask(&terminator));
2326       }
2327     }
2328 
2329     gc_task_manager()->execute_and_wait(q);
2330   }
2331 
2332   // Process reference objects found during marking
2333   {
2334     TraceTime tm_r("reference processing", print_phases(), true, gclog_or_tty);
2335     if (ref_processor()->processing_is_mt()) {
2336       RefProcTaskExecutor task_executor;
2337       ref_processor()->process_discovered_references(
2338         is_alive_closure(), &mark_and_push_closure, &follow_stack_closure,
2339         &task_executor);
2340     } else {
2341       ref_processor()->process_discovered_references(
2342         is_alive_closure(), &mark_and_push_closure, &follow_stack_closure, NULL);
2343     }
2344   }
2345 
2346   TraceTime tm_c("class unloading", print_phases(), true, gclog_or_tty);
2347 
2348   // This is the point where the entire marking should have completed.
2349   assert(cm->marking_stacks_empty(), "Marking should have completed");
2350 
2351   // Follow system dictionary roots and unload classes.
2352   bool purged_class = SystemDictionary::do_unloading(is_alive_closure());
2353 
2354   // Unload nmethods.
2355   CodeCache::do_unloading(is_alive_closure(), purged_class);
2356 
2357   // Prune dead klasses from subklass/sibling/implementor lists.
2358   Klass::clean_weak_klass_links(is_alive_closure());
2359 
2360   // Delete entries for dead interned strings.
2361   StringTable::unlink(is_alive_closure());
2362 
2363   // Clean up unreferenced symbols in symbol table.
2364   SymbolTable::unlink();
2365 }
2366 
2367 void PSParallelCompact::follow_klass(ParCompactionManager* cm, Klass* klass) {
2368   ClassLoaderData* cld = klass->class_loader_data();
2369   // The actual processing of the klass is done when we
2370   // traverse the list of Klasses in the class loader data.
2371   PSParallelCompact::follow_class_loader(cm, cld);
2372 }
2373 
2374 void PSParallelCompact::adjust_klass(ParCompactionManager* cm, Klass* klass) {
2375   ClassLoaderData* cld = klass->class_loader_data();
2376   // The actual processing of the klass is done when we
2377   // traverse the list of Klasses in the class loader data.
2378   PSParallelCompact::adjust_class_loader(cm, cld);
2379 }
2380 
2381 void PSParallelCompact::follow_class_loader(ParCompactionManager* cm,
2382                                             ClassLoaderData* cld) {
2383   PSParallelCompact::MarkAndPushClosure mark_and_push_closure(cm);
2384   PSParallelCompact::FollowKlassClosure follow_klass_closure(&mark_and_push_closure);
2385 
2386   cld->oops_do(&mark_and_push_closure, &follow_klass_closure, true);
2387 }
2388 
2389 void PSParallelCompact::adjust_class_loader(ParCompactionManager* cm,
2390                                             ClassLoaderData* cld) {
2391   cld->oops_do(PSParallelCompact::adjust_pointer_closure(),
2392                PSParallelCompact::adjust_klass_closure(),
2393                true);
2394 }
2395 
2396 // This should be moved to the shared markSweep code!
2397 class PSAlwaysTrueClosure: public BoolObjectClosure {
2398 public:
2399   void do_object(oop p) { ShouldNotReachHere(); }
2400   bool do_object_b(oop p) { return true; }
2401 };
2402 static PSAlwaysTrueClosure always_true;
2403 
2404 void PSParallelCompact::adjust_roots() {
2405   // Adjust the pointers to reflect the new locations
2406   TraceTime tm("adjust roots", print_phases(), true, gclog_or_tty);
2407 
2408   // Need new claim bits when tracing through and adjusting pointers.
2409   ClassLoaderDataGraph::clear_claimed_marks();
2410 
2411   // General strong roots.
2412   Universe::oops_do(adjust_pointer_closure());
2413   JNIHandles::oops_do(adjust_pointer_closure());   // Global (strong) JNI handles
2414   CLDToOopClosure adjust_from_cld(adjust_pointer_closure());
2415   Threads::oops_do(adjust_pointer_closure(), &adjust_from_cld, NULL);
2416   ObjectSynchronizer::oops_do(adjust_pointer_closure());
2417   FlatProfiler::oops_do(adjust_pointer_closure());
2418   Management::oops_do(adjust_pointer_closure());
2419   JvmtiExport::oops_do(adjust_pointer_closure());
2420   // SO_AllClasses
2421   SystemDictionary::oops_do(adjust_pointer_closure());
2422   ClassLoaderDataGraph::oops_do(adjust_pointer_closure(), adjust_klass_closure(), true);
2423 
2424   // Now adjust pointers in remaining weak roots.  (All of which should
2425   // have been cleared if they pointed to non-surviving objects.)
2426   // Global (weak) JNI handles
2427   JNIHandles::weak_oops_do(&always_true, adjust_pointer_closure());
2428 
2429   CodeCache::oops_do(adjust_pointer_closure());
2430   StringTable::oops_do(adjust_pointer_closure());
2431   ref_processor()->weak_oops_do(adjust_pointer_closure());
2432   // Roots were visited so references into the young gen in roots
2433   // may have been scanned.  Process them also.
2434   // Should the reference processor have a span that excludes
2435   // young gen objects?
2436   PSScavenge::reference_processor()->weak_oops_do(adjust_pointer_closure());
2437 }
2438 
2439 void PSParallelCompact::enqueue_region_draining_tasks(GCTaskQueue* q,
2440                                                       uint parallel_gc_threads)
2441 {
2442   TraceTime tm("drain task setup", print_phases(), true, gclog_or_tty);
2443 
2444   // Find the threads that are active
2445   unsigned int which = 0;
2446 
2447   const uint task_count = MAX2(parallel_gc_threads, 1U);
2448   for (uint j = 0; j < task_count; j++) {
2449     q->enqueue(new DrainStacksCompactionTask(j));
2450     ParCompactionManager::verify_region_list_empty(j);
2451     // Set the region stacks variables to "no" region stack values
2452     // so that they will be recognized and needing a region stack
2453     // in the stealing tasks if they do not get one by executing
2454     // a draining stack.
2455     ParCompactionManager* cm = ParCompactionManager::manager_array(j);
2456     cm->set_region_stack(NULL);
2457     cm->set_region_stack_index((uint)max_uintx);
2458   }
2459   ParCompactionManager::reset_recycled_stack_index();
2460 
2461   // Find all regions that are available (can be filled immediately) and
2462   // distribute them to the thread stacks.  The iteration is done in reverse
2463   // order (high to low) so the regions will be removed in ascending order.
2464 
2465   const ParallelCompactData& sd = PSParallelCompact::summary_data();
2466 
2467   size_t fillable_regions = 0;   // A count for diagnostic purposes.
2468   // A region index which corresponds to the tasks created above.
2469   // "which" must be 0 <= which < task_count
2470 
2471   which = 0;
2472   // id + 1 is used to test termination so unsigned  can
2473   // be used with an old_space_id == 0.
2474   for (unsigned int id = to_space_id; id + 1 > old_space_id; --id) {
2475     SpaceInfo* const space_info = _space_info + id;
2476     MutableSpace* const space = space_info->space();
2477     HeapWord* const new_top = space_info->new_top();
2478 
2479     const size_t beg_region = sd.addr_to_region_idx(space_info->dense_prefix());
2480     const size_t end_region =
2481       sd.addr_to_region_idx(sd.region_align_up(new_top));
2482 
2483     for (size_t cur = end_region - 1; cur + 1 > beg_region; --cur) {
2484       if (sd.region(cur)->claim_unsafe()) {
2485         ParCompactionManager::region_list_push(which, cur);
2486 
2487         if (TraceParallelOldGCCompactionPhase && Verbose) {
2488           const size_t count_mod_8 = fillable_regions & 7;
2489           if (count_mod_8 == 0) gclog_or_tty->print("fillable: ");
2490           gclog_or_tty->print(" " SIZE_FORMAT_W(7), cur);
2491           if (count_mod_8 == 7) gclog_or_tty->cr();
2492         }
2493 
2494         NOT_PRODUCT(++fillable_regions;)
2495 
2496         // Assign regions to tasks in round-robin fashion.
2497         if (++which == task_count) {
2498           assert(which <= parallel_gc_threads,
2499             "Inconsistent number of workers");
2500           which = 0;
2501         }
2502       }
2503     }
2504   }
2505 
2506   if (TraceParallelOldGCCompactionPhase) {
2507     if (Verbose && (fillable_regions & 7) != 0) gclog_or_tty->cr();
2508     gclog_or_tty->print_cr("%u initially fillable regions", fillable_regions);
2509   }
2510 }
2511 
2512 #define PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING 4
2513 
2514 void PSParallelCompact::enqueue_dense_prefix_tasks(GCTaskQueue* q,
2515                                                     uint parallel_gc_threads) {
2516   TraceTime tm("dense prefix task setup", print_phases(), true, gclog_or_tty);
2517 
2518   ParallelCompactData& sd = PSParallelCompact::summary_data();
2519 
2520   // Iterate over all the spaces adding tasks for updating
2521   // regions in the dense prefix.  Assume that 1 gc thread
2522   // will work on opening the gaps and the remaining gc threads
2523   // will work on the dense prefix.
2524   unsigned int space_id;
2525   for (space_id = old_space_id; space_id < last_space_id; ++ space_id) {
2526     HeapWord* const dense_prefix_end = _space_info[space_id].dense_prefix();
2527     const MutableSpace* const space = _space_info[space_id].space();
2528 
2529     if (dense_prefix_end == space->bottom()) {
2530       // There is no dense prefix for this space.
2531       continue;
2532     }
2533 
2534     // The dense prefix is before this region.
2535     size_t region_index_end_dense_prefix =
2536         sd.addr_to_region_idx(dense_prefix_end);
2537     RegionData* const dense_prefix_cp =
2538       sd.region(region_index_end_dense_prefix);
2539     assert(dense_prefix_end == space->end() ||
2540            dense_prefix_cp->available() ||
2541            dense_prefix_cp->claimed(),
2542            "The region after the dense prefix should always be ready to fill");
2543 
2544     size_t region_index_start = sd.addr_to_region_idx(space->bottom());
2545 
2546     // Is there dense prefix work?
2547     size_t total_dense_prefix_regions =
2548       region_index_end_dense_prefix - region_index_start;
2549     // How many regions of the dense prefix should be given to
2550     // each thread?
2551     if (total_dense_prefix_regions > 0) {
2552       uint tasks_for_dense_prefix = 1;
2553       if (total_dense_prefix_regions <=
2554           (parallel_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING)) {
2555         // Don't over partition.  This assumes that
2556         // PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING is a small integer value
2557         // so there are not many regions to process.
2558         tasks_for_dense_prefix = parallel_gc_threads;
2559       } else {
2560         // Over partition
2561         tasks_for_dense_prefix = parallel_gc_threads *
2562           PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING;
2563       }
2564       size_t regions_per_thread = total_dense_prefix_regions /
2565         tasks_for_dense_prefix;
2566       // Give each thread at least 1 region.
2567       if (regions_per_thread == 0) {
2568         regions_per_thread = 1;
2569       }
2570 
2571       for (uint k = 0; k < tasks_for_dense_prefix; k++) {
2572         if (region_index_start >= region_index_end_dense_prefix) {
2573           break;
2574         }
2575         // region_index_end is not processed
2576         size_t region_index_end = MIN2(region_index_start + regions_per_thread,
2577                                        region_index_end_dense_prefix);
2578         q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id),
2579                                              region_index_start,
2580                                              region_index_end));
2581         region_index_start = region_index_end;
2582       }
2583     }
2584     // This gets any part of the dense prefix that did not
2585     // fit evenly.
2586     if (region_index_start < region_index_end_dense_prefix) {
2587       q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id),
2588                                            region_index_start,
2589                                            region_index_end_dense_prefix));
2590     }
2591   }
2592 }
2593 
2594 void PSParallelCompact::enqueue_region_stealing_tasks(
2595                                      GCTaskQueue* q,
2596                                      ParallelTaskTerminator* terminator_ptr,
2597                                      uint parallel_gc_threads) {
2598   TraceTime tm("steal task setup", print_phases(), true, gclog_or_tty);
2599 
2600   // Once a thread has drained it's stack, it should try to steal regions from
2601   // other threads.
2602   if (parallel_gc_threads > 1) {
2603     for (uint j = 0; j < parallel_gc_threads; j++) {
2604       q->enqueue(new StealRegionCompactionTask(terminator_ptr));
2605     }
2606   }
2607 }
2608 
2609 void PSParallelCompact::compact() {
2610   // trace("5");
2611   TraceTime tm("compaction phase", print_phases(), true, gclog_or_tty);
2612 
2613   ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
2614   assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
2615   PSOldGen* old_gen = heap->old_gen();
2616   old_gen->start_array()->reset();
2617   uint parallel_gc_threads = heap->gc_task_manager()->workers();
2618   uint active_gc_threads = heap->gc_task_manager()->active_workers();
2619   TaskQueueSetSuper* qset = ParCompactionManager::region_array();
2620   ParallelTaskTerminator terminator(active_gc_threads, qset);
2621 
2622   GCTaskQueue* q = GCTaskQueue::create();
2623   enqueue_region_draining_tasks(q, active_gc_threads);
2624   enqueue_dense_prefix_tasks(q, active_gc_threads);
2625   enqueue_region_stealing_tasks(q, &terminator, active_gc_threads);
2626 
2627   {
2628     TraceTime tm_pc("par compact", print_phases(), true, gclog_or_tty);
2629 
2630     gc_task_manager()->execute_and_wait(q);
2631 
2632 #ifdef  ASSERT
2633     // Verify that all regions have been processed before the deferred updates.
2634     for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2635       verify_complete(SpaceId(id));
2636     }
2637 #endif
2638   }
2639 
2640   {
2641     // Update the deferred objects, if any.  Any compaction manager can be used.
2642     TraceTime tm_du("deferred updates", print_phases(), true, gclog_or_tty);
2643     ParCompactionManager* cm = ParCompactionManager::manager_array(0);
2644     for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2645       update_deferred_objects(cm, SpaceId(id));
2646     }
2647   }
2648 }
2649 
2650 #ifdef  ASSERT
2651 void PSParallelCompact::verify_complete(SpaceId space_id) {
2652   // All Regions between space bottom() to new_top() should be marked as filled
2653   // and all Regions between new_top() and top() should be available (i.e.,
2654   // should have been emptied).
2655   ParallelCompactData& sd = summary_data();
2656   SpaceInfo si = _space_info[space_id];
2657   HeapWord* new_top_addr = sd.region_align_up(si.new_top());
2658   HeapWord* old_top_addr = sd.region_align_up(si.space()->top());
2659   const size_t beg_region = sd.addr_to_region_idx(si.space()->bottom());
2660   const size_t new_top_region = sd.addr_to_region_idx(new_top_addr);
2661   const size_t old_top_region = sd.addr_to_region_idx(old_top_addr);
2662 
2663   bool issued_a_warning = false;
2664 
2665   size_t cur_region;
2666   for (cur_region = beg_region; cur_region < new_top_region; ++cur_region) {
2667     const RegionData* const c = sd.region(cur_region);
2668     if (!c->completed()) {
2669       warning("region " SIZE_FORMAT " not filled:  "
2670               "destination_count=" SIZE_FORMAT,
2671               cur_region, c->destination_count());
2672       issued_a_warning = true;
2673     }
2674   }
2675 
2676   for (cur_region = new_top_region; cur_region < old_top_region; ++cur_region) {
2677     const RegionData* const c = sd.region(cur_region);
2678     if (!c->available()) {
2679       warning("region " SIZE_FORMAT " not empty:   "
2680               "destination_count=" SIZE_FORMAT,
2681               cur_region, c->destination_count());
2682       issued_a_warning = true;
2683     }
2684   }
2685 
2686   if (issued_a_warning) {
2687     print_region_ranges();
2688   }
2689 }
2690 #endif  // #ifdef ASSERT
2691 
2692 // Update interior oops in the ranges of regions [beg_region, end_region).
2693 void
2694 PSParallelCompact::update_and_deadwood_in_dense_prefix(ParCompactionManager* cm,
2695                                                        SpaceId space_id,
2696                                                        size_t beg_region,
2697                                                        size_t end_region) {
2698   ParallelCompactData& sd = summary_data();
2699   ParMarkBitMap* const mbm = mark_bitmap();
2700 
2701   HeapWord* beg_addr = sd.region_to_addr(beg_region);
2702   HeapWord* const end_addr = sd.region_to_addr(end_region);
2703   assert(beg_region <= end_region, "bad region range");
2704   assert(end_addr <= dense_prefix(space_id), "not in the dense prefix");
2705 
2706 #ifdef  ASSERT
2707   // Claim the regions to avoid triggering an assert when they are marked as
2708   // filled.
2709   for (size_t claim_region = beg_region; claim_region < end_region; ++claim_region) {
2710     assert(sd.region(claim_region)->claim_unsafe(), "claim() failed");
2711   }
2712 #endif  // #ifdef ASSERT
2713 
2714   if (beg_addr != space(space_id)->bottom()) {
2715     // Find the first live object or block of dead space that *starts* in this
2716     // range of regions.  If a partial object crosses onto the region, skip it;
2717     // it will be marked for 'deferred update' when the object head is
2718     // processed.  If dead space crosses onto the region, it is also skipped; it
2719     // will be filled when the prior region is processed.  If neither of those
2720     // apply, the first word in the region is the start of a live object or dead
2721     // space.
2722     assert(beg_addr > space(space_id)->bottom(), "sanity");
2723     const RegionData* const cp = sd.region(beg_region);
2724     if (cp->partial_obj_size() != 0) {
2725       beg_addr = sd.partial_obj_end(beg_region);
2726     } else if (dead_space_crosses_boundary(cp, mbm->addr_to_bit(beg_addr))) {
2727       beg_addr = mbm->find_obj_beg(beg_addr, end_addr);
2728     }
2729   }
2730 
2731   if (beg_addr < end_addr) {
2732     // A live object or block of dead space starts in this range of Regions.
2733      HeapWord* const dense_prefix_end = dense_prefix(space_id);
2734 
2735     // Create closures and iterate.
2736     UpdateOnlyClosure update_closure(mbm, cm, space_id);
2737     FillClosure fill_closure(cm, space_id);
2738     ParMarkBitMap::IterationStatus status;
2739     status = mbm->iterate(&update_closure, &fill_closure, beg_addr, end_addr,
2740                           dense_prefix_end);
2741     if (status == ParMarkBitMap::incomplete) {
2742       update_closure.do_addr(update_closure.source());
2743     }
2744   }
2745 
2746   // Mark the regions as filled.
2747   RegionData* const beg_cp = sd.region(beg_region);
2748   RegionData* const end_cp = sd.region(end_region);
2749   for (RegionData* cp = beg_cp; cp < end_cp; ++cp) {
2750     cp->set_completed();
2751   }
2752 }
2753 
2754 // Return the SpaceId for the space containing addr.  If addr is not in the
2755 // heap, last_space_id is returned.  In debug mode it expects the address to be
2756 // in the heap and asserts such.
2757 PSParallelCompact::SpaceId PSParallelCompact::space_id(HeapWord* addr) {
2758   assert(Universe::heap()->is_in_reserved(addr), "addr not in the heap");
2759 
2760   for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2761     if (_space_info[id].space()->contains(addr)) {
2762       return SpaceId(id);
2763     }
2764   }
2765 
2766   assert(false, "no space contains the addr");
2767   return last_space_id;
2768 }
2769 
2770 void PSParallelCompact::update_deferred_objects(ParCompactionManager* cm,
2771                                                 SpaceId id) {
2772   assert(id < last_space_id, "bad space id");
2773 
2774   ParallelCompactData& sd = summary_data();
2775   const SpaceInfo* const space_info = _space_info + id;
2776   ObjectStartArray* const start_array = space_info->start_array();
2777 
2778   const MutableSpace* const space = space_info->space();
2779   assert(space_info->dense_prefix() >= space->bottom(), "dense_prefix not set");
2780   HeapWord* const beg_addr = space_info->dense_prefix();
2781   HeapWord* const end_addr = sd.region_align_up(space_info->new_top());
2782 
2783   const RegionData* const beg_region = sd.addr_to_region_ptr(beg_addr);
2784   const RegionData* const end_region = sd.addr_to_region_ptr(end_addr);
2785   const RegionData* cur_region;
2786   for (cur_region = beg_region; cur_region < end_region; ++cur_region) {
2787     HeapWord* const addr = cur_region->deferred_obj_addr();
2788     if (addr != NULL) {
2789       if (start_array != NULL) {
2790         start_array->allocate_block(addr);
2791       }
2792       oop(addr)->update_contents(cm);
2793       assert(oop(addr)->is_oop_or_null(), "should be an oop now");
2794     }
2795   }
2796 }
2797 
2798 // Skip over count live words starting from beg, and return the address of the
2799 // next live word.  Unless marked, the word corresponding to beg is assumed to
2800 // be dead.  Callers must either ensure beg does not correspond to the middle of
2801 // an object, or account for those live words in some other way.  Callers must
2802 // also ensure that there are enough live words in the range [beg, end) to skip.
2803 HeapWord*
2804 PSParallelCompact::skip_live_words(HeapWord* beg, HeapWord* end, size_t count)
2805 {
2806   assert(count > 0, "sanity");
2807 
2808   ParMarkBitMap* m = mark_bitmap();
2809   idx_t bits_to_skip = m->words_to_bits(count);
2810   idx_t cur_beg = m->addr_to_bit(beg);
2811   const idx_t search_end = BitMap::word_align_up(m->addr_to_bit(end));
2812 
2813   do {
2814     cur_beg = m->find_obj_beg(cur_beg, search_end);
2815     idx_t cur_end = m->find_obj_end(cur_beg, search_end);
2816     const size_t obj_bits = cur_end - cur_beg + 1;
2817     if (obj_bits > bits_to_skip) {
2818       return m->bit_to_addr(cur_beg + bits_to_skip);
2819     }
2820     bits_to_skip -= obj_bits;
2821     cur_beg = cur_end + 1;
2822   } while (bits_to_skip > 0);
2823 
2824   // Skipping the desired number of words landed just past the end of an object.
2825   // Find the start of the next object.
2826   cur_beg = m->find_obj_beg(cur_beg, search_end);
2827   assert(cur_beg < m->addr_to_bit(end), "not enough live words to skip");
2828   return m->bit_to_addr(cur_beg);
2829 }
2830 
2831 HeapWord* PSParallelCompact::first_src_addr(HeapWord* const dest_addr,
2832                                             SpaceId src_space_id,
2833                                             size_t src_region_idx)
2834 {
2835   assert(summary_data().is_region_aligned(dest_addr), "not aligned");
2836 
2837   const SplitInfo& split_info = _space_info[src_space_id].split_info();
2838   if (split_info.dest_region_addr() == dest_addr) {
2839     // The partial object ending at the split point contains the first word to
2840     // be copied to dest_addr.
2841     return split_info.first_src_addr();
2842   }
2843 
2844   const ParallelCompactData& sd = summary_data();
2845   ParMarkBitMap* const bitmap = mark_bitmap();
2846   const size_t RegionSize = ParallelCompactData::RegionSize;
2847 
2848   assert(sd.is_region_aligned(dest_addr), "not aligned");
2849   const RegionData* const src_region_ptr = sd.region(src_region_idx);
2850   const size_t partial_obj_size = src_region_ptr->partial_obj_size();
2851   HeapWord* const src_region_destination = src_region_ptr->destination();
2852 
2853   assert(dest_addr >= src_region_destination, "wrong src region");
2854   assert(src_region_ptr->data_size() > 0, "src region cannot be empty");
2855 
2856   HeapWord* const src_region_beg = sd.region_to_addr(src_region_idx);
2857   HeapWord* const src_region_end = src_region_beg + RegionSize;
2858 
2859   HeapWord* addr = src_region_beg;
2860   if (dest_addr == src_region_destination) {
2861     // Return the first live word in the source region.
2862     if (partial_obj_size == 0) {
2863       addr = bitmap->find_obj_beg(addr, src_region_end);
2864       assert(addr < src_region_end, "no objects start in src region");
2865     }
2866     return addr;
2867   }
2868 
2869   // Must skip some live data.
2870   size_t words_to_skip = dest_addr - src_region_destination;
2871   assert(src_region_ptr->data_size() > words_to_skip, "wrong src region");
2872 
2873   if (partial_obj_size >= words_to_skip) {
2874     // All the live words to skip are part of the partial object.
2875     addr += words_to_skip;
2876     if (partial_obj_size == words_to_skip) {
2877       // Find the first live word past the partial object.
2878       addr = bitmap->find_obj_beg(addr, src_region_end);
2879       assert(addr < src_region_end, "wrong src region");
2880     }
2881     return addr;
2882   }
2883 
2884   // Skip over the partial object (if any).
2885   if (partial_obj_size != 0) {
2886     words_to_skip -= partial_obj_size;
2887     addr += partial_obj_size;
2888   }
2889 
2890   // Skip over live words due to objects that start in the region.
2891   addr = skip_live_words(addr, src_region_end, words_to_skip);
2892   assert(addr < src_region_end, "wrong src region");
2893   return addr;
2894 }
2895 
2896 void PSParallelCompact::decrement_destination_counts(ParCompactionManager* cm,
2897                                                      SpaceId src_space_id,
2898                                                      size_t beg_region,
2899                                                      HeapWord* end_addr)
2900 {
2901   ParallelCompactData& sd = summary_data();
2902 
2903 #ifdef ASSERT
2904   MutableSpace* const src_space = _space_info[src_space_id].space();
2905   HeapWord* const beg_addr = sd.region_to_addr(beg_region);
2906   assert(src_space->contains(beg_addr) || beg_addr == src_space->end(),
2907          "src_space_id does not match beg_addr");
2908   assert(src_space->contains(end_addr) || end_addr == src_space->end(),
2909          "src_space_id does not match end_addr");
2910 #endif // #ifdef ASSERT
2911 
2912   RegionData* const beg = sd.region(beg_region);
2913   RegionData* const end = sd.addr_to_region_ptr(sd.region_align_up(end_addr));
2914 
2915   // Regions up to new_top() are enqueued if they become available.
2916   HeapWord* const new_top = _space_info[src_space_id].new_top();
2917   RegionData* const enqueue_end =
2918     sd.addr_to_region_ptr(sd.region_align_up(new_top));
2919 
2920   for (RegionData* cur = beg; cur < end; ++cur) {
2921     assert(cur->data_size() > 0, "region must have live data");
2922     cur->decrement_destination_count();
2923     if (cur < enqueue_end && cur->available() && cur->claim()) {
2924       cm->push_region(sd.region(cur));
2925     }
2926   }
2927 }
2928 
2929 size_t PSParallelCompact::next_src_region(MoveAndUpdateClosure& closure,
2930                                           SpaceId& src_space_id,
2931                                           HeapWord*& src_space_top,
2932                                           HeapWord* end_addr)
2933 {
2934   typedef ParallelCompactData::RegionData RegionData;
2935 
2936   ParallelCompactData& sd = PSParallelCompact::summary_data();
2937   const size_t region_size = ParallelCompactData::RegionSize;
2938 
2939   size_t src_region_idx = 0;
2940 
2941   // Skip empty regions (if any) up to the top of the space.
2942   HeapWord* const src_aligned_up = sd.region_align_up(end_addr);
2943   RegionData* src_region_ptr = sd.addr_to_region_ptr(src_aligned_up);
2944   HeapWord* const top_aligned_up = sd.region_align_up(src_space_top);
2945   const RegionData* const top_region_ptr =
2946     sd.addr_to_region_ptr(top_aligned_up);
2947   while (src_region_ptr < top_region_ptr && src_region_ptr->data_size() == 0) {
2948     ++src_region_ptr;
2949   }
2950 
2951   if (src_region_ptr < top_region_ptr) {
2952     // The next source region is in the current space.  Update src_region_idx
2953     // and the source address to match src_region_ptr.
2954     src_region_idx = sd.region(src_region_ptr);
2955     HeapWord* const src_region_addr = sd.region_to_addr(src_region_idx);
2956     if (src_region_addr > closure.source()) {
2957       closure.set_source(src_region_addr);
2958     }
2959     return src_region_idx;
2960   }
2961 
2962   // Switch to a new source space and find the first non-empty region.
2963   unsigned int space_id = src_space_id + 1;
2964   assert(space_id < last_space_id, "not enough spaces");
2965 
2966   HeapWord* const destination = closure.destination();
2967 
2968   do {
2969     MutableSpace* space = _space_info[space_id].space();
2970     HeapWord* const bottom = space->bottom();
2971     const RegionData* const bottom_cp = sd.addr_to_region_ptr(bottom);
2972 
2973     // Iterate over the spaces that do not compact into themselves.
2974     if (bottom_cp->destination() != bottom) {
2975       HeapWord* const top_aligned_up = sd.region_align_up(space->top());
2976       const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
2977 
2978       for (const RegionData* src_cp = bottom_cp; src_cp < top_cp; ++src_cp) {
2979         if (src_cp->live_obj_size() > 0) {
2980           // Found it.
2981           assert(src_cp->destination() == destination,
2982                  "first live obj in the space must match the destination");
2983           assert(src_cp->partial_obj_size() == 0,
2984                  "a space cannot begin with a partial obj");
2985 
2986           src_space_id = SpaceId(space_id);
2987           src_space_top = space->top();
2988           const size_t src_region_idx = sd.region(src_cp);
2989           closure.set_source(sd.region_to_addr(src_region_idx));
2990           return src_region_idx;
2991         } else {
2992           assert(src_cp->data_size() == 0, "sanity");
2993         }
2994       }
2995     }
2996   } while (++space_id < last_space_id);
2997 
2998   assert(false, "no source region was found");
2999   return 0;
3000 }
3001 
3002 void PSParallelCompact::fill_region(ParCompactionManager* cm, size_t region_idx)
3003 {
3004   typedef ParMarkBitMap::IterationStatus IterationStatus;
3005   const size_t RegionSize = ParallelCompactData::RegionSize;
3006   ParMarkBitMap* const bitmap = mark_bitmap();
3007   ParallelCompactData& sd = summary_data();
3008   RegionData* const region_ptr = sd.region(region_idx);
3009 
3010   // Get the items needed to construct the closure.
3011   HeapWord* dest_addr = sd.region_to_addr(region_idx);
3012   SpaceId dest_space_id = space_id(dest_addr);
3013   ObjectStartArray* start_array = _space_info[dest_space_id].start_array();
3014   HeapWord* new_top = _space_info[dest_space_id].new_top();
3015   assert(dest_addr < new_top, "sanity");
3016   const size_t words = MIN2(pointer_delta(new_top, dest_addr), RegionSize);
3017 
3018   // Get the source region and related info.
3019   size_t src_region_idx = region_ptr->source_region();
3020   SpaceId src_space_id = space_id(sd.region_to_addr(src_region_idx));
3021   HeapWord* src_space_top = _space_info[src_space_id].space()->top();
3022 
3023   MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words);
3024   closure.set_source(first_src_addr(dest_addr, src_space_id, src_region_idx));
3025 
3026   // Adjust src_region_idx to prepare for decrementing destination counts (the
3027   // destination count is not decremented when a region is copied to itself).
3028   if (src_region_idx == region_idx) {
3029     src_region_idx += 1;
3030   }
3031 
3032   if (bitmap->is_unmarked(closure.source())) {
3033     // The first source word is in the middle of an object; copy the remainder
3034     // of the object or as much as will fit.  The fact that pointer updates were
3035     // deferred will be noted when the object header is processed.
3036     HeapWord* const old_src_addr = closure.source();
3037     closure.copy_partial_obj();
3038     if (closure.is_full()) {
3039       decrement_destination_counts(cm, src_space_id, src_region_idx,
3040                                    closure.source());
3041       region_ptr->set_deferred_obj_addr(NULL);
3042       region_ptr->set_completed();
3043       return;
3044     }
3045 
3046     HeapWord* const end_addr = sd.region_align_down(closure.source());
3047     if (sd.region_align_down(old_src_addr) != end_addr) {
3048       // The partial object was copied from more than one source region.
3049       decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
3050 
3051       // Move to the next source region, possibly switching spaces as well.  All
3052       // args except end_addr may be modified.
3053       src_region_idx = next_src_region(closure, src_space_id, src_space_top,
3054                                        end_addr);
3055     }
3056   }
3057 
3058   do {
3059     HeapWord* const cur_addr = closure.source();
3060     HeapWord* const end_addr = MIN2(sd.region_align_up(cur_addr + 1),
3061                                     src_space_top);
3062     IterationStatus status = bitmap->iterate(&closure, cur_addr, end_addr);
3063 
3064     if (status == ParMarkBitMap::incomplete) {
3065       // The last obj that starts in the source region does not end in the
3066       // region.
3067       assert(closure.source() < end_addr, "sanity");
3068       HeapWord* const obj_beg = closure.source();
3069       HeapWord* const range_end = MIN2(obj_beg + closure.words_remaining(),
3070                                        src_space_top);
3071       HeapWord* const obj_end = bitmap->find_obj_end(obj_beg, range_end);
3072       if (obj_end < range_end) {
3073         // The end was found; the entire object will fit.
3074         status = closure.do_addr(obj_beg, bitmap->obj_size(obj_beg, obj_end));
3075         assert(status != ParMarkBitMap::would_overflow, "sanity");
3076       } else {
3077         // The end was not found; the object will not fit.
3078         assert(range_end < src_space_top, "obj cannot cross space boundary");
3079         status = ParMarkBitMap::would_overflow;
3080       }
3081     }
3082 
3083     if (status == ParMarkBitMap::would_overflow) {
3084       // The last object did not fit.  Note that interior oop updates were
3085       // deferred, then copy enough of the object to fill the region.
3086       region_ptr->set_deferred_obj_addr(closure.destination());
3087       status = closure.copy_until_full(); // copies from closure.source()
3088 
3089       decrement_destination_counts(cm, src_space_id, src_region_idx,
3090                                    closure.source());
3091       region_ptr->set_completed();
3092       return;
3093     }
3094 
3095     if (status == ParMarkBitMap::full) {
3096       decrement_destination_counts(cm, src_space_id, src_region_idx,
3097                                    closure.source());
3098       region_ptr->set_deferred_obj_addr(NULL);
3099       region_ptr->set_completed();
3100       return;
3101     }
3102 
3103     decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
3104 
3105     // Move to the next source region, possibly switching spaces as well.  All
3106     // args except end_addr may be modified.
3107     src_region_idx = next_src_region(closure, src_space_id, src_space_top,
3108                                      end_addr);
3109   } while (true);
3110 }
3111 
3112 void
3113 PSParallelCompact::move_and_update(ParCompactionManager* cm, SpaceId space_id) {
3114   const MutableSpace* sp = space(space_id);
3115   if (sp->is_empty()) {
3116     return;
3117   }
3118 
3119   ParallelCompactData& sd = PSParallelCompact::summary_data();
3120   ParMarkBitMap* const bitmap = mark_bitmap();
3121   HeapWord* const dp_addr = dense_prefix(space_id);
3122   HeapWord* beg_addr = sp->bottom();
3123   HeapWord* end_addr = sp->top();
3124 
3125   assert(beg_addr <= dp_addr && dp_addr <= end_addr, "bad dense prefix");
3126 
3127   const size_t beg_region = sd.addr_to_region_idx(beg_addr);
3128   const size_t dp_region = sd.addr_to_region_idx(dp_addr);
3129   if (beg_region < dp_region) {
3130     update_and_deadwood_in_dense_prefix(cm, space_id, beg_region, dp_region);
3131   }
3132 
3133   // The destination of the first live object that starts in the region is one
3134   // past the end of the partial object entering the region (if any).
3135   HeapWord* const dest_addr = sd.partial_obj_end(dp_region);
3136   HeapWord* const new_top = _space_info[space_id].new_top();
3137   assert(new_top >= dest_addr, "bad new_top value");
3138   const size_t words = pointer_delta(new_top, dest_addr);
3139 
3140   if (words > 0) {
3141     ObjectStartArray* start_array = _space_info[space_id].start_array();
3142     MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words);
3143 
3144     ParMarkBitMap::IterationStatus status;
3145     status = bitmap->iterate(&closure, dest_addr, end_addr);
3146     assert(status == ParMarkBitMap::full, "iteration not complete");
3147     assert(bitmap->find_obj_beg(closure.source(), end_addr) == end_addr,
3148            "live objects skipped because closure is full");
3149   }
3150 }
3151 
3152 jlong PSParallelCompact::millis_since_last_gc() {
3153   // We need a monotonically non-deccreasing time in ms but
3154   // os::javaTimeMillis() does not guarantee monotonicity.
3155   jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
3156   jlong ret_val = now - _time_of_last_gc;
3157   // XXX See note in genCollectedHeap::millis_since_last_gc().
3158   if (ret_val < 0) {
3159     NOT_PRODUCT(warning("time warp: "INT64_FORMAT, ret_val);)
3160     return 0;
3161   }
3162   return ret_val;
3163 }
3164 
3165 void PSParallelCompact::reset_millis_since_last_gc() {
3166   // We need a monotonically non-deccreasing time in ms but
3167   // os::javaTimeMillis() does not guarantee monotonicity.
3168   _time_of_last_gc = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
3169 }
3170 
3171 ParMarkBitMap::IterationStatus MoveAndUpdateClosure::copy_until_full()
3172 {
3173   if (source() != destination()) {
3174     DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3175     Copy::aligned_conjoint_words(source(), destination(), words_remaining());
3176   }
3177   update_state(words_remaining());
3178   assert(is_full(), "sanity");
3179   return ParMarkBitMap::full;
3180 }
3181 
3182 void MoveAndUpdateClosure::copy_partial_obj()
3183 {
3184   size_t words = words_remaining();
3185 
3186   HeapWord* const range_end = MIN2(source() + words, bitmap()->region_end());
3187   HeapWord* const end_addr = bitmap()->find_obj_end(source(), range_end);
3188   if (end_addr < range_end) {
3189     words = bitmap()->obj_size(source(), end_addr);
3190   }
3191 
3192   // This test is necessary; if omitted, the pointer updates to a partial object
3193   // that crosses the dense prefix boundary could be overwritten.
3194   if (source() != destination()) {
3195     DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3196     Copy::aligned_conjoint_words(source(), destination(), words);
3197   }
3198   update_state(words);
3199 }
3200 
3201 ParMarkBitMapClosure::IterationStatus
3202 MoveAndUpdateClosure::do_addr(HeapWord* addr, size_t words) {
3203   assert(destination() != NULL, "sanity");
3204   assert(bitmap()->obj_size(addr) == words, "bad size");
3205 
3206   _source = addr;
3207   assert(PSParallelCompact::summary_data().calc_new_pointer(source()) ==
3208          destination(), "wrong destination");
3209 
3210   if (words > words_remaining()) {
3211     return ParMarkBitMap::would_overflow;
3212   }
3213 
3214   // The start_array must be updated even if the object is not moving.
3215   if (_start_array != NULL) {
3216     _start_array->allocate_block(destination());
3217   }
3218 
3219   if (destination() != source()) {
3220     DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3221     Copy::aligned_conjoint_words(source(), destination(), words);
3222   }
3223 
3224   oop moved_oop = (oop) destination();
3225   moved_oop->update_contents(compaction_manager());
3226   assert(moved_oop->is_oop_or_null(), "Object should be whole at this point");
3227 
3228   update_state(words);
3229   assert(destination() == (HeapWord*)moved_oop + moved_oop->size(), "sanity");
3230   return is_full() ? ParMarkBitMap::full : ParMarkBitMap::incomplete;
3231 }
3232 
3233 UpdateOnlyClosure::UpdateOnlyClosure(ParMarkBitMap* mbm,
3234                                      ParCompactionManager* cm,
3235                                      PSParallelCompact::SpaceId space_id) :
3236   ParMarkBitMapClosure(mbm, cm),
3237   _space_id(space_id),
3238   _start_array(PSParallelCompact::start_array(space_id))
3239 {
3240 }
3241 
3242 // Updates the references in the object to their new values.
3243 ParMarkBitMapClosure::IterationStatus
3244 UpdateOnlyClosure::do_addr(HeapWord* addr, size_t words) {
3245   do_addr(addr);
3246   return ParMarkBitMap::incomplete;
3247 }