1 /*
   2  * Copyright (c) 2005, 2013, 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   _reserved_byte_size = 0;
 360   _region_data = 0;
 361   _region_count = 0;
 362 }
 363 
 364 bool ParallelCompactData::initialize(MemRegion covered_region)
 365 {
 366   _region_start = covered_region.start();
 367   const size_t region_size = covered_region.word_size();
 368   DEBUG_ONLY(_region_end = _region_start + region_size;)
 369 
 370   assert(region_align_down(_region_start) == _region_start,
 371          "region start not aligned");
 372   assert((region_size & RegionSizeOffsetMask) == 0,
 373          "region size not a multiple of RegionSize");
 374 
 375   bool result = initialize_region_data(region_size);
 376 
 377   return result;
 378 }
 379 
 380 PSVirtualSpace*
 381 ParallelCompactData::create_vspace(size_t count, size_t element_size)
 382 {
 383   const size_t raw_bytes = count * element_size;
 384   const size_t page_sz = os::page_size_for_region(raw_bytes, raw_bytes, 10);
 385   const size_t granularity = os::vm_allocation_granularity();
 386   _reserved_byte_size = align_size_up(raw_bytes, MAX2(page_sz, granularity));
 387 
 388   const size_t rs_align = page_sz == (size_t) os::vm_page_size() ? 0 :
 389     MAX2(page_sz, granularity);
 390   ReservedSpace rs(_reserved_byte_size, rs_align, rs_align > 0);
 391   os::trace_page_sizes("par compact", raw_bytes, raw_bytes, page_sz, rs.base(),
 392                        rs.size());
 393 
 394   MemTracker::record_virtual_memory_type((address)rs.base(), mtGC);
 395 
 396   PSVirtualSpace* vspace = new PSVirtualSpace(rs, page_sz);
 397   if (vspace != 0) {
 398     if (vspace->expand_by(_reserved_byte_size)) {
 399       return vspace;
 400     }
 401     delete vspace;
 402     // Release memory reserved in the space.
 403     rs.release();
 404   }
 405 
 406   return 0;
 407 }
 408 
 409 bool ParallelCompactData::initialize_region_data(size_t region_size)
 410 {
 411   const size_t count = (region_size + RegionSizeOffsetMask) >> Log2RegionSize;
 412   _region_vspace = create_vspace(count, sizeof(RegionData));
 413   if (_region_vspace != 0) {
 414     _region_data = (RegionData*)_region_vspace->reserved_low_addr();
 415     _region_count = count;
 416     return true;
 417   }
 418   return false;
 419 }
 420 
 421 void ParallelCompactData::clear()
 422 {
 423   memset(_region_data, 0, _region_vspace->committed_size());
 424 }
 425 
 426 void ParallelCompactData::clear_range(size_t beg_region, size_t end_region) {
 427   assert(beg_region <= _region_count, "beg_region out of range");
 428   assert(end_region <= _region_count, "end_region out of range");
 429 
 430   const size_t region_cnt = end_region - beg_region;
 431   memset(_region_data + beg_region, 0, region_cnt * sizeof(RegionData));
 432 }
 433 
 434 HeapWord* ParallelCompactData::partial_obj_end(size_t region_idx) const
 435 {
 436   const RegionData* cur_cp = region(region_idx);
 437   const RegionData* const end_cp = region(region_count() - 1);
 438 
 439   HeapWord* result = region_to_addr(region_idx);
 440   if (cur_cp < end_cp) {
 441     do {
 442       result += cur_cp->partial_obj_size();
 443     } while (cur_cp->partial_obj_size() == RegionSize && ++cur_cp < end_cp);
 444   }
 445   return result;
 446 }
 447 
 448 void ParallelCompactData::add_obj(HeapWord* addr, size_t len)
 449 {
 450   const size_t obj_ofs = pointer_delta(addr, _region_start);
 451   const size_t beg_region = obj_ofs >> Log2RegionSize;
 452   const size_t end_region = (obj_ofs + len - 1) >> Log2RegionSize;
 453 
 454   DEBUG_ONLY(Atomic::inc_ptr(&add_obj_count);)
 455   DEBUG_ONLY(Atomic::add_ptr(len, &add_obj_size);)
 456 
 457   if (beg_region == end_region) {
 458     // All in one region.
 459     _region_data[beg_region].add_live_obj(len);
 460     return;
 461   }
 462 
 463   // First region.
 464   const size_t beg_ofs = region_offset(addr);
 465   _region_data[beg_region].add_live_obj(RegionSize - beg_ofs);
 466 
 467   Klass* klass = ((oop)addr)->klass();
 468   // Middle regions--completely spanned by this object.
 469   for (size_t region = beg_region + 1; region < end_region; ++region) {
 470     _region_data[region].set_partial_obj_size(RegionSize);
 471     _region_data[region].set_partial_obj_addr(addr);
 472   }
 473 
 474   // Last region.
 475   const size_t end_ofs = region_offset(addr + len - 1);
 476   _region_data[end_region].set_partial_obj_size(end_ofs + 1);
 477   _region_data[end_region].set_partial_obj_addr(addr);
 478 }
 479 
 480 void
 481 ParallelCompactData::summarize_dense_prefix(HeapWord* beg, HeapWord* end)
 482 {
 483   assert(region_offset(beg) == 0, "not RegionSize aligned");
 484   assert(region_offset(end) == 0, "not RegionSize aligned");
 485 
 486   size_t cur_region = addr_to_region_idx(beg);
 487   const size_t end_region = addr_to_region_idx(end);
 488   HeapWord* addr = beg;
 489   while (cur_region < end_region) {
 490     _region_data[cur_region].set_destination(addr);
 491     _region_data[cur_region].set_destination_count(0);
 492     _region_data[cur_region].set_source_region(cur_region);
 493     _region_data[cur_region].set_data_location(addr);
 494 
 495     // Update live_obj_size so the region appears completely full.
 496     size_t live_size = RegionSize - _region_data[cur_region].partial_obj_size();
 497     _region_data[cur_region].set_live_obj_size(live_size);
 498 
 499     ++cur_region;
 500     addr += RegionSize;
 501   }
 502 }
 503 
 504 // Find the point at which a space can be split and, if necessary, record the
 505 // split point.
 506 //
 507 // If the current src region (which overflowed the destination space) doesn't
 508 // have a partial object, the split point is at the beginning of the current src
 509 // region (an "easy" split, no extra bookkeeping required).
 510 //
 511 // If the current src region has a partial object, the split point is in the
 512 // region where that partial object starts (call it the split_region).  If
 513 // split_region has a partial object, then the split point is just after that
 514 // partial object (a "hard" split where we have to record the split data and
 515 // zero the partial_obj_size field).  With a "hard" split, we know that the
 516 // partial_obj ends within split_region because the partial object that caused
 517 // the overflow starts in split_region.  If split_region doesn't have a partial
 518 // obj, then the split is at the beginning of split_region (another "easy"
 519 // split).
 520 HeapWord*
 521 ParallelCompactData::summarize_split_space(size_t src_region,
 522                                            SplitInfo& split_info,
 523                                            HeapWord* destination,
 524                                            HeapWord* target_end,
 525                                            HeapWord** target_next)
 526 {
 527   assert(destination <= target_end, "sanity");
 528   assert(destination + _region_data[src_region].data_size() > target_end,
 529     "region should not fit into target space");
 530   assert(is_region_aligned(target_end), "sanity");
 531 
 532   size_t split_region = src_region;
 533   HeapWord* split_destination = destination;
 534   size_t partial_obj_size = _region_data[src_region].partial_obj_size();
 535 
 536   if (destination + partial_obj_size > target_end) {
 537     // The split point is just after the partial object (if any) in the
 538     // src_region that contains the start of the object that overflowed the
 539     // destination space.
 540     //
 541     // Find the start of the "overflow" object and set split_region to the
 542     // region containing it.
 543     HeapWord* const overflow_obj = _region_data[src_region].partial_obj_addr();
 544     split_region = addr_to_region_idx(overflow_obj);
 545 
 546     // Clear the source_region field of all destination regions whose first word
 547     // came from data after the split point (a non-null source_region field
 548     // implies a region must be filled).
 549     //
 550     // An alternative to the simple loop below:  clear during post_compact(),
 551     // which uses memcpy instead of individual stores, and is easy to
 552     // parallelize.  (The downside is that it clears the entire RegionData
 553     // object as opposed to just one field.)
 554     //
 555     // post_compact() would have to clear the summary data up to the highest
 556     // address that was written during the summary phase, which would be
 557     //
 558     //         max(top, max(new_top, clear_top))
 559     //
 560     // where clear_top is a new field in SpaceInfo.  Would have to set clear_top
 561     // to target_end.
 562     const RegionData* const sr = region(split_region);
 563     const size_t beg_idx =
 564       addr_to_region_idx(region_align_up(sr->destination() +
 565                                          sr->partial_obj_size()));
 566     const size_t end_idx = addr_to_region_idx(target_end);
 567 
 568     if (TraceParallelOldGCSummaryPhase) {
 569         gclog_or_tty->print_cr("split:  clearing source_region field in ["
 570                                SIZE_FORMAT ", " SIZE_FORMAT ")",
 571                                beg_idx, end_idx);
 572     }
 573     for (size_t idx = beg_idx; idx < end_idx; ++idx) {
 574       _region_data[idx].set_source_region(0);
 575     }
 576 
 577     // Set split_destination and partial_obj_size to reflect the split region.
 578     split_destination = sr->destination();
 579     partial_obj_size = sr->partial_obj_size();
 580   }
 581 
 582   // The split is recorded only if a partial object extends onto the region.
 583   if (partial_obj_size != 0) {
 584     _region_data[split_region].set_partial_obj_size(0);
 585     split_info.record(split_region, partial_obj_size, split_destination);
 586   }
 587 
 588   // Setup the continuation addresses.
 589   *target_next = split_destination + partial_obj_size;
 590   HeapWord* const source_next = region_to_addr(split_region) + partial_obj_size;
 591 
 592   if (TraceParallelOldGCSummaryPhase) {
 593     const char * split_type = partial_obj_size == 0 ? "easy" : "hard";
 594     gclog_or_tty->print_cr("%s split:  src=" PTR_FORMAT " src_c=" SIZE_FORMAT
 595                            " pos=" SIZE_FORMAT,
 596                            split_type, source_next, split_region,
 597                            partial_obj_size);
 598     gclog_or_tty->print_cr("%s split:  dst=" PTR_FORMAT " dst_c=" SIZE_FORMAT
 599                            " tn=" PTR_FORMAT,
 600                            split_type, split_destination,
 601                            addr_to_region_idx(split_destination),
 602                            *target_next);
 603 
 604     if (partial_obj_size != 0) {
 605       HeapWord* const po_beg = split_info.destination();
 606       HeapWord* const po_end = po_beg + split_info.partial_obj_size();
 607       gclog_or_tty->print_cr("%s split:  "
 608                              "po_beg=" PTR_FORMAT " " SIZE_FORMAT " "
 609                              "po_end=" PTR_FORMAT " " SIZE_FORMAT,
 610                              split_type,
 611                              po_beg, addr_to_region_idx(po_beg),
 612                              po_end, addr_to_region_idx(po_end));
 613     }
 614   }
 615 
 616   return source_next;
 617 }
 618 
 619 bool ParallelCompactData::summarize(SplitInfo& split_info,
 620                                     HeapWord* source_beg, HeapWord* source_end,
 621                                     HeapWord** source_next,
 622                                     HeapWord* target_beg, HeapWord* target_end,
 623                                     HeapWord** target_next)
 624 {
 625   if (TraceParallelOldGCSummaryPhase) {
 626     HeapWord* const source_next_val = source_next == NULL ? NULL : *source_next;
 627     tty->print_cr("sb=" PTR_FORMAT " se=" PTR_FORMAT " sn=" PTR_FORMAT
 628                   "tb=" PTR_FORMAT " te=" PTR_FORMAT " tn=" PTR_FORMAT,
 629                   source_beg, source_end, source_next_val,
 630                   target_beg, target_end, *target_next);
 631   }
 632 
 633   size_t cur_region = addr_to_region_idx(source_beg);
 634   const size_t end_region = addr_to_region_idx(region_align_up(source_end));
 635 
 636   HeapWord *dest_addr = target_beg;
 637   while (cur_region < end_region) {
 638     // The destination must be set even if the region has no data.
 639     _region_data[cur_region].set_destination(dest_addr);
 640 
 641     size_t words = _region_data[cur_region].data_size();
 642     if (words > 0) {
 643       // If cur_region does not fit entirely into the target space, find a point
 644       // at which the source space can be 'split' so that part is copied to the
 645       // target space and the rest is copied elsewhere.
 646       if (dest_addr + words > target_end) {
 647         assert(source_next != NULL, "source_next is NULL when splitting");
 648         *source_next = summarize_split_space(cur_region, split_info, dest_addr,
 649                                              target_end, target_next);
 650         return false;
 651       }
 652 
 653       // Compute the destination_count for cur_region, and if necessary, update
 654       // source_region for a destination region.  The source_region field is
 655       // updated if cur_region is the first (left-most) region to be copied to a
 656       // destination region.
 657       //
 658       // The destination_count calculation is a bit subtle.  A region that has
 659       // data that compacts into itself does not count itself as a destination.
 660       // This maintains the invariant that a zero count means the region is
 661       // available and can be claimed and then filled.
 662       uint destination_count = 0;
 663       if (split_info.is_split(cur_region)) {
 664         // The current region has been split:  the partial object will be copied
 665         // to one destination space and the remaining data will be copied to
 666         // another destination space.  Adjust the initial destination_count and,
 667         // if necessary, set the source_region field if the partial object will
 668         // cross a destination region boundary.
 669         destination_count = split_info.destination_count();
 670         if (destination_count == 2) {
 671           size_t dest_idx = addr_to_region_idx(split_info.dest_region_addr());
 672           _region_data[dest_idx].set_source_region(cur_region);
 673         }
 674       }
 675 
 676       HeapWord* const last_addr = dest_addr + words - 1;
 677       const size_t dest_region_1 = addr_to_region_idx(dest_addr);
 678       const size_t dest_region_2 = addr_to_region_idx(last_addr);
 679 
 680       // Initially assume that the destination regions will be the same and
 681       // adjust the value below if necessary.  Under this assumption, if
 682       // cur_region == dest_region_2, then cur_region will be compacted
 683       // completely into itself.
 684       destination_count += cur_region == dest_region_2 ? 0 : 1;
 685       if (dest_region_1 != dest_region_2) {
 686         // Destination regions differ; adjust destination_count.
 687         destination_count += 1;
 688         // Data from cur_region will be copied to the start of dest_region_2.
 689         _region_data[dest_region_2].set_source_region(cur_region);
 690       } else if (region_offset(dest_addr) == 0) {
 691         // Data from cur_region will be copied to the start of the destination
 692         // region.
 693         _region_data[dest_region_1].set_source_region(cur_region);
 694       }
 695 
 696       _region_data[cur_region].set_destination_count(destination_count);
 697       _region_data[cur_region].set_data_location(region_to_addr(cur_region));
 698       dest_addr += words;
 699     }
 700 
 701     ++cur_region;
 702   }
 703 
 704   *target_next = dest_addr;
 705   return true;
 706 }
 707 
 708 HeapWord* ParallelCompactData::calc_new_pointer(HeapWord* addr) {
 709   assert(addr != NULL, "Should detect NULL oop earlier");
 710   assert(PSParallelCompact::gc_heap()->is_in(addr), "addr not in heap");
 711 #ifdef ASSERT
 712   if (PSParallelCompact::mark_bitmap()->is_unmarked(addr)) {
 713     gclog_or_tty->print_cr("calc_new_pointer:: addr " PTR_FORMAT, addr);
 714   }
 715 #endif
 716   assert(PSParallelCompact::mark_bitmap()->is_marked(addr), "obj not marked");
 717 
 718   // Region covering the object.
 719   size_t region_index = addr_to_region_idx(addr);
 720   const RegionData* const region_ptr = region(region_index);
 721   HeapWord* const region_addr = region_align_down(addr);
 722 
 723   assert(addr < region_addr + RegionSize, "Region does not cover object");
 724   assert(addr_to_region_ptr(region_addr) == region_ptr, "sanity check");
 725 
 726   HeapWord* result = region_ptr->destination();
 727 
 728   // If all the data in the region is live, then the new location of the object
 729   // can be calculated from the destination of the region plus the offset of the
 730   // object in the region.
 731   if (region_ptr->data_size() == RegionSize) {
 732     result += pointer_delta(addr, region_addr);
 733     DEBUG_ONLY(PSParallelCompact::check_new_location(addr, result);)
 734     return result;
 735   }
 736 
 737   // The new location of the object is
 738   //    region destination +
 739   //    size of the partial object extending onto the region +
 740   //    sizes of the live objects in the Region that are to the left of addr
 741   const size_t partial_obj_size = region_ptr->partial_obj_size();
 742   HeapWord* const search_start = region_addr + partial_obj_size;
 743 
 744   const ParMarkBitMap* bitmap = PSParallelCompact::mark_bitmap();
 745   size_t live_to_left = bitmap->live_words_in_range(search_start, oop(addr));
 746 
 747   result += partial_obj_size + live_to_left;
 748   DEBUG_ONLY(PSParallelCompact::check_new_location(addr, result);)
 749   return result;
 750 }
 751 
 752 #ifdef  ASSERT
 753 void ParallelCompactData::verify_clear(const PSVirtualSpace* vspace)
 754 {
 755   const size_t* const beg = (const size_t*)vspace->committed_low_addr();
 756   const size_t* const end = (const size_t*)vspace->committed_high_addr();
 757   for (const size_t* p = beg; p < end; ++p) {
 758     assert(*p == 0, "not zero");
 759   }
 760 }
 761 
 762 void ParallelCompactData::verify_clear()
 763 {
 764   verify_clear(_region_vspace);
 765 }
 766 #endif  // #ifdef ASSERT
 767 
 768 #ifdef NOT_PRODUCT
 769 ParallelCompactData::RegionData* debug_region(size_t region_index) {
 770   ParallelCompactData& sd = PSParallelCompact::summary_data();
 771   return sd.region(region_index);
 772 }
 773 #endif
 774 
 775 elapsedTimer        PSParallelCompact::_accumulated_time;
 776 unsigned int        PSParallelCompact::_total_invocations = 0;
 777 unsigned int        PSParallelCompact::_maximum_compaction_gc_num = 0;
 778 jlong               PSParallelCompact::_time_of_last_gc = 0;
 779 CollectorCounters*  PSParallelCompact::_counters = NULL;
 780 ParMarkBitMap       PSParallelCompact::_mark_bitmap;
 781 ParallelCompactData PSParallelCompact::_summary_data;
 782 
 783 PSParallelCompact::IsAliveClosure PSParallelCompact::_is_alive_closure;
 784 
 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(
 845       err_msg("Unable to allocate " SIZE_FORMAT "KB bitmaps for parallel "
 846       "garbage collection for the requested " SIZE_FORMAT "KB heap.",
 847       _mark_bitmap.reserved_byte_size()/K, mr.byte_size()/K));
 848     return false;
 849   }
 850 
 851   if (!_summary_data.initialize(mr)) {
 852     vm_shutdown_during_initialization(
 853       err_msg("Unable to allocate " SIZE_FORMAT "KB card tables for parallel "
 854       "garbage collection for the requested " SIZE_FORMAT "KB heap.",
 855       _summary_data.reserved_byte_size()/K, mr.byte_size()/K));
 856     return false;
 857   }
 858 
 859   return true;
 860 }
 861 
 862 void PSParallelCompact::initialize_space_info()
 863 {
 864   memset(&_space_info, 0, sizeof(_space_info));
 865 
 866   ParallelScavengeHeap* heap = gc_heap();
 867   PSYoungGen* young_gen = heap->young_gen();
 868 
 869   _space_info[old_space_id].set_space(heap->old_gen()->object_space());
 870   _space_info[eden_space_id].set_space(young_gen->eden_space());
 871   _space_info[from_space_id].set_space(young_gen->from_space());
 872   _space_info[to_space_id].set_space(young_gen->to_space());
 873 
 874   _space_info[old_space_id].set_start_array(heap->old_gen()->start_array());
 875 }
 876 
 877 void PSParallelCompact::initialize_dead_wood_limiter()
 878 {
 879   const size_t max = 100;
 880   _dwl_mean = double(MIN2(ParallelOldDeadWoodLimiterMean, max)) / 100.0;
 881   _dwl_std_dev = double(MIN2(ParallelOldDeadWoodLimiterStdDev, max)) / 100.0;
 882   _dwl_first_term = 1.0 / (sqrt(2.0 * M_PI) * _dwl_std_dev);
 883   DEBUG_ONLY(_dwl_initialized = true;)
 884   _dwl_adjustment = normal_distribution(1.0);
 885 }
 886 
 887 // Simple class for storing info about the heap at the start of GC, to be used
 888 // after GC for comparison/printing.
 889 class PreGCValues {
 890 public:
 891   PreGCValues() { }
 892   PreGCValues(ParallelScavengeHeap* heap) { fill(heap); }
 893 
 894   void fill(ParallelScavengeHeap* heap) {
 895     _heap_used      = heap->used();
 896     _young_gen_used = heap->young_gen()->used_in_bytes();
 897     _old_gen_used   = heap->old_gen()->used_in_bytes();
 898     _metadata_used  = MetaspaceAux::allocated_used_bytes();
 899   };
 900 
 901   size_t heap_used() const      { return _heap_used; }
 902   size_t young_gen_used() const { return _young_gen_used; }
 903   size_t old_gen_used() const   { return _old_gen_used; }
 904   size_t metadata_used() const  { return _metadata_used; }
 905 
 906 private:
 907   size_t _heap_used;
 908   size_t _young_gen_used;
 909   size_t _old_gen_used;
 910   size_t _metadata_used;
 911 };
 912 
 913 void
 914 PSParallelCompact::clear_data_covering_space(SpaceId id)
 915 {
 916   // At this point, top is the value before GC, new_top() is the value that will
 917   // be set at the end of GC.  The marking bitmap is cleared to top; nothing
 918   // should be marked above top.  The summary data is cleared to the larger of
 919   // top & new_top.
 920   MutableSpace* const space = _space_info[id].space();
 921   HeapWord* const bot = space->bottom();
 922   HeapWord* const top = space->top();
 923   HeapWord* const max_top = MAX2(top, _space_info[id].new_top());
 924 
 925   const idx_t beg_bit = _mark_bitmap.addr_to_bit(bot);
 926   const idx_t end_bit = BitMap::word_align_up(_mark_bitmap.addr_to_bit(top));
 927   _mark_bitmap.clear_range(beg_bit, end_bit);
 928 
 929   const size_t beg_region = _summary_data.addr_to_region_idx(bot);
 930   const size_t end_region =
 931     _summary_data.addr_to_region_idx(_summary_data.region_align_up(max_top));
 932   _summary_data.clear_range(beg_region, end_region);
 933 
 934   // Clear the data used to 'split' regions.
 935   SplitInfo& split_info = _space_info[id].split_info();
 936   if (split_info.is_valid()) {
 937     split_info.clear();
 938   }
 939   DEBUG_ONLY(split_info.verify_clear();)
 940 }
 941 
 942 void PSParallelCompact::pre_compact(PreGCValues* pre_gc_values)
 943 {
 944   // Update the from & to space pointers in space_info, since they are swapped
 945   // at each young gen gc.  Do the update unconditionally (even though a
 946   // promotion failure does not swap spaces) because an unknown number of minor
 947   // collections will have swapped the spaces an unknown number of times.
 948   TraceTime tm("pre compact", print_phases(), true, gclog_or_tty);
 949   ParallelScavengeHeap* heap = gc_heap();
 950   _space_info[from_space_id].set_space(heap->young_gen()->from_space());
 951   _space_info[to_space_id].set_space(heap->young_gen()->to_space());
 952 
 953   pre_gc_values->fill(heap);
 954 
 955   DEBUG_ONLY(add_obj_count = add_obj_size = 0;)
 956   DEBUG_ONLY(mark_bitmap_count = mark_bitmap_size = 0;)
 957 
 958   // Increment the invocation count
 959   heap->increment_total_collections(true);
 960 
 961   // We need to track unique mark sweep invocations as well.
 962   _total_invocations++;
 963 
 964   heap->print_heap_before_gc();
 965 
 966   // Fill in TLABs
 967   heap->accumulate_statistics_all_tlabs();
 968   heap->ensure_parsability(true);  // retire TLABs
 969 
 970   if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
 971     HandleMark hm;  // Discard invalid handles created during verification
 972     Universe::verify(" VerifyBeforeGC:");
 973   }
 974 
 975   // Verify object start arrays
 976   if (VerifyObjectStartArray &&
 977       VerifyBeforeGC) {
 978     heap->old_gen()->verify_object_start_array();
 979   }
 980 
 981   DEBUG_ONLY(mark_bitmap()->verify_clear();)
 982   DEBUG_ONLY(summary_data().verify_clear();)
 983 
 984   // Have worker threads release resources the next time they run a task.
 985   gc_task_manager()->release_all_resources();
 986 }
 987 
 988 void PSParallelCompact::post_compact()
 989 {
 990   TraceTime tm("post compact", print_phases(), true, gclog_or_tty);
 991 
 992   for (unsigned int id = old_space_id; id < last_space_id; ++id) {
 993     // Clear the marking bitmap, summary data and split info.
 994     clear_data_covering_space(SpaceId(id));
 995     // Update top().  Must be done after clearing the bitmap and summary data.
 996     _space_info[id].publish_new_top();
 997   }
 998 
 999   MutableSpace* const eden_space = _space_info[eden_space_id].space();
1000   MutableSpace* const from_space = _space_info[from_space_id].space();
1001   MutableSpace* const to_space   = _space_info[to_space_id].space();
1002 
1003   ParallelScavengeHeap* heap = gc_heap();
1004   bool eden_empty = eden_space->is_empty();
1005   if (!eden_empty) {
1006     eden_empty = absorb_live_data_from_eden(heap->size_policy(),
1007                                             heap->young_gen(), heap->old_gen());
1008   }
1009 
1010   // Update heap occupancy information which is used as input to the soft ref
1011   // clearing policy at the next gc.
1012   Universe::update_heap_info_at_gc();
1013 
1014   bool young_gen_empty = eden_empty && from_space->is_empty() &&
1015     to_space->is_empty();
1016 
1017   BarrierSet* bs = heap->barrier_set();
1018   if (bs->is_a(BarrierSet::ModRef)) {
1019     ModRefBarrierSet* modBS = (ModRefBarrierSet*)bs;
1020     MemRegion old_mr = heap->old_gen()->reserved();
1021 
1022     if (young_gen_empty) {
1023       modBS->clear(MemRegion(old_mr.start(), old_mr.end()));
1024     } else {
1025       modBS->invalidate(MemRegion(old_mr.start(), old_mr.end()));
1026     }
1027   }
1028 
1029   // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1030   ClassLoaderDataGraph::purge();
1031   MetaspaceAux::verify_metrics();
1032 
1033   Threads::gc_epilogue();
1034   CodeCache::gc_epilogue();
1035   JvmtiExport::gc_epilogue();
1036 
1037   COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1038 
1039   ref_processor()->enqueue_discovered_references(NULL);
1040 
1041   if (ZapUnusedHeapArea) {
1042     heap->gen_mangle_unused_area();
1043   }
1044 
1045   // Update time of last GC
1046   reset_millis_since_last_gc();
1047 }
1048 
1049 HeapWord*
1050 PSParallelCompact::compute_dense_prefix_via_density(const SpaceId id,
1051                                                     bool maximum_compaction)
1052 {
1053   const size_t region_size = ParallelCompactData::RegionSize;
1054   const ParallelCompactData& sd = summary_data();
1055 
1056   const MutableSpace* const space = _space_info[id].space();
1057   HeapWord* const top_aligned_up = sd.region_align_up(space->top());
1058   const RegionData* const beg_cp = sd.addr_to_region_ptr(space->bottom());
1059   const RegionData* const end_cp = sd.addr_to_region_ptr(top_aligned_up);
1060 
1061   // Skip full regions at the beginning of the space--they are necessarily part
1062   // of the dense prefix.
1063   size_t full_count = 0;
1064   const RegionData* cp;
1065   for (cp = beg_cp; cp < end_cp && cp->data_size() == region_size; ++cp) {
1066     ++full_count;
1067   }
1068 
1069   assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");
1070   const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;
1071   const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval;
1072   if (maximum_compaction || cp == end_cp || interval_ended) {
1073     _maximum_compaction_gc_num = total_invocations();
1074     return sd.region_to_addr(cp);
1075   }
1076 
1077   HeapWord* const new_top = _space_info[id].new_top();
1078   const size_t space_live = pointer_delta(new_top, space->bottom());
1079   const size_t space_used = space->used_in_words();
1080   const size_t space_capacity = space->capacity_in_words();
1081 
1082   const double cur_density = double(space_live) / space_capacity;
1083   const double deadwood_density =
1084     (1.0 - cur_density) * (1.0 - cur_density) * cur_density * cur_density;
1085   const size_t deadwood_goal = size_t(space_capacity * deadwood_density);
1086 
1087   if (TraceParallelOldGCDensePrefix) {
1088     tty->print_cr("cur_dens=%5.3f dw_dens=%5.3f dw_goal=" SIZE_FORMAT,
1089                   cur_density, deadwood_density, deadwood_goal);
1090     tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " "
1091                   "space_cap=" SIZE_FORMAT,
1092                   space_live, space_used,
1093                   space_capacity);
1094   }
1095 
1096   // XXX - Use binary search?
1097   HeapWord* dense_prefix = sd.region_to_addr(cp);
1098   const RegionData* full_cp = cp;
1099   const RegionData* const top_cp = sd.addr_to_region_ptr(space->top() - 1);
1100   while (cp < end_cp) {
1101     HeapWord* region_destination = cp->destination();
1102     const size_t cur_deadwood = pointer_delta(dense_prefix, region_destination);
1103     if (TraceParallelOldGCDensePrefix && Verbose) {
1104       tty->print_cr("c#=" SIZE_FORMAT_W(4) " dst=" PTR_FORMAT " "
1105                     "dp=" SIZE_FORMAT_W(8) " " "cdw=" SIZE_FORMAT_W(8),
1106                     sd.region(cp), region_destination,
1107                     dense_prefix, cur_deadwood);
1108     }
1109 
1110     if (cur_deadwood >= deadwood_goal) {
1111       // Found the region that has the correct amount of deadwood to the left.
1112       // This typically occurs after crossing a fairly sparse set of regions, so
1113       // iterate backwards over those sparse regions, looking for the region
1114       // that has the lowest density of live objects 'to the right.'
1115       size_t space_to_left = sd.region(cp) * region_size;
1116       size_t live_to_left = space_to_left - cur_deadwood;
1117       size_t space_to_right = space_capacity - space_to_left;
1118       size_t live_to_right = space_live - live_to_left;
1119       double density_to_right = double(live_to_right) / space_to_right;
1120       while (cp > full_cp) {
1121         --cp;
1122         const size_t prev_region_live_to_right = live_to_right -
1123           cp->data_size();
1124         const size_t prev_region_space_to_right = space_to_right + region_size;
1125         double prev_region_density_to_right =
1126           double(prev_region_live_to_right) / prev_region_space_to_right;
1127         if (density_to_right <= prev_region_density_to_right) {
1128           return dense_prefix;
1129         }
1130         if (TraceParallelOldGCDensePrefix && Verbose) {
1131           tty->print_cr("backing up from c=" SIZE_FORMAT_W(4) " d2r=%10.8f "
1132                         "pc_d2r=%10.8f", sd.region(cp), density_to_right,
1133                         prev_region_density_to_right);
1134         }
1135         dense_prefix -= region_size;
1136         live_to_right = prev_region_live_to_right;
1137         space_to_right = prev_region_space_to_right;
1138         density_to_right = prev_region_density_to_right;
1139       }
1140       return dense_prefix;
1141     }
1142 
1143     dense_prefix += region_size;
1144     ++cp;
1145   }
1146 
1147   return dense_prefix;
1148 }
1149 
1150 #ifndef PRODUCT
1151 void PSParallelCompact::print_dense_prefix_stats(const char* const algorithm,
1152                                                  const SpaceId id,
1153                                                  const bool maximum_compaction,
1154                                                  HeapWord* const addr)
1155 {
1156   const size_t region_idx = summary_data().addr_to_region_idx(addr);
1157   RegionData* const cp = summary_data().region(region_idx);
1158   const MutableSpace* const space = _space_info[id].space();
1159   HeapWord* const new_top = _space_info[id].new_top();
1160 
1161   const size_t space_live = pointer_delta(new_top, space->bottom());
1162   const size_t dead_to_left = pointer_delta(addr, cp->destination());
1163   const size_t space_cap = space->capacity_in_words();
1164   const double dead_to_left_pct = double(dead_to_left) / space_cap;
1165   const size_t live_to_right = new_top - cp->destination();
1166   const size_t dead_to_right = space->top() - addr - live_to_right;
1167 
1168   tty->print_cr("%s=" PTR_FORMAT " dpc=" SIZE_FORMAT_W(5) " "
1169                 "spl=" SIZE_FORMAT " "
1170                 "d2l=" SIZE_FORMAT " d2l%%=%6.4f "
1171                 "d2r=" SIZE_FORMAT " l2r=" SIZE_FORMAT
1172                 " ratio=%10.8f",
1173                 algorithm, addr, region_idx,
1174                 space_live,
1175                 dead_to_left, dead_to_left_pct,
1176                 dead_to_right, live_to_right,
1177                 double(dead_to_right) / live_to_right);
1178 }
1179 #endif  // #ifndef PRODUCT
1180 
1181 // Return a fraction indicating how much of the generation can be treated as
1182 // "dead wood" (i.e., not reclaimed).  The function uses a normal distribution
1183 // based on the density of live objects in the generation to determine a limit,
1184 // which is then adjusted so the return value is min_percent when the density is
1185 // 1.
1186 //
1187 // The following table shows some return values for a different values of the
1188 // standard deviation (ParallelOldDeadWoodLimiterStdDev); the mean is 0.5 and
1189 // min_percent is 1.
1190 //
1191 //                          fraction allowed as dead wood
1192 //         -----------------------------------------------------------------
1193 // density std_dev=70 std_dev=75 std_dev=80 std_dev=85 std_dev=90 std_dev=95
1194 // ------- ---------- ---------- ---------- ---------- ---------- ----------
1195 // 0.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
1196 // 0.05000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
1197 // 0.10000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
1198 // 0.15000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
1199 // 0.20000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
1200 // 0.25000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
1201 // 0.30000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
1202 // 0.35000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
1203 // 0.40000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
1204 // 0.45000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
1205 // 0.50000 0.13832410 0.11599237 0.09847664 0.08456518 0.07338887 0.06431510
1206 // 0.55000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
1207 // 0.60000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
1208 // 0.65000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
1209 // 0.70000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
1210 // 0.75000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
1211 // 0.80000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
1212 // 0.85000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
1213 // 0.90000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
1214 // 0.95000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
1215 // 1.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
1216 
1217 double PSParallelCompact::dead_wood_limiter(double density, size_t min_percent)
1218 {
1219   assert(_dwl_initialized, "uninitialized");
1220 
1221   // The raw limit is the value of the normal distribution at x = density.
1222   const double raw_limit = normal_distribution(density);
1223 
1224   // Adjust the raw limit so it becomes the minimum when the density is 1.
1225   //
1226   // First subtract the adjustment value (which is simply the precomputed value
1227   // normal_distribution(1.0)); this yields a value of 0 when the density is 1.
1228   // Then add the minimum value, so the minimum is returned when the density is
1229   // 1.  Finally, prevent negative values, which occur when the mean is not 0.5.
1230   const double min = double(min_percent) / 100.0;
1231   const double limit = raw_limit - _dwl_adjustment + min;
1232   return MAX2(limit, 0.0);
1233 }
1234 
1235 ParallelCompactData::RegionData*
1236 PSParallelCompact::first_dead_space_region(const RegionData* beg,
1237                                            const RegionData* end)
1238 {
1239   const size_t region_size = ParallelCompactData::RegionSize;
1240   ParallelCompactData& sd = summary_data();
1241   size_t left = sd.region(beg);
1242   size_t right = end > beg ? sd.region(end) - 1 : left;
1243 
1244   // Binary search.
1245   while (left < right) {
1246     // Equivalent to (left + right) / 2, but does not overflow.
1247     const size_t middle = left + (right - left) / 2;
1248     RegionData* const middle_ptr = sd.region(middle);
1249     HeapWord* const dest = middle_ptr->destination();
1250     HeapWord* const addr = sd.region_to_addr(middle);
1251     assert(dest != NULL, "sanity");
1252     assert(dest <= addr, "must move left");
1253 
1254     if (middle > left && dest < addr) {
1255       right = middle - 1;
1256     } else if (middle < right && middle_ptr->data_size() == region_size) {
1257       left = middle + 1;
1258     } else {
1259       return middle_ptr;
1260     }
1261   }
1262   return sd.region(left);
1263 }
1264 
1265 ParallelCompactData::RegionData*
1266 PSParallelCompact::dead_wood_limit_region(const RegionData* beg,
1267                                           const RegionData* end,
1268                                           size_t dead_words)
1269 {
1270   ParallelCompactData& sd = summary_data();
1271   size_t left = sd.region(beg);
1272   size_t right = end > beg ? sd.region(end) - 1 : left;
1273 
1274   // Binary search.
1275   while (left < right) {
1276     // Equivalent to (left + right) / 2, but does not overflow.
1277     const size_t middle = left + (right - left) / 2;
1278     RegionData* const middle_ptr = sd.region(middle);
1279     HeapWord* const dest = middle_ptr->destination();
1280     HeapWord* const addr = sd.region_to_addr(middle);
1281     assert(dest != NULL, "sanity");
1282     assert(dest <= addr, "must move left");
1283 
1284     const size_t dead_to_left = pointer_delta(addr, dest);
1285     if (middle > left && dead_to_left > dead_words) {
1286       right = middle - 1;
1287     } else if (middle < right && dead_to_left < dead_words) {
1288       left = middle + 1;
1289     } else {
1290       return middle_ptr;
1291     }
1292   }
1293   return sd.region(left);
1294 }
1295 
1296 // The result is valid during the summary phase, after the initial summarization
1297 // of each space into itself, and before final summarization.
1298 inline double
1299 PSParallelCompact::reclaimed_ratio(const RegionData* const cp,
1300                                    HeapWord* const bottom,
1301                                    HeapWord* const top,
1302                                    HeapWord* const new_top)
1303 {
1304   ParallelCompactData& sd = summary_data();
1305 
1306   assert(cp != NULL, "sanity");
1307   assert(bottom != NULL, "sanity");
1308   assert(top != NULL, "sanity");
1309   assert(new_top != NULL, "sanity");
1310   assert(top >= new_top, "summary data problem?");
1311   assert(new_top > bottom, "space is empty; should not be here");
1312   assert(new_top >= cp->destination(), "sanity");
1313   assert(top >= sd.region_to_addr(cp), "sanity");
1314 
1315   HeapWord* const destination = cp->destination();
1316   const size_t dense_prefix_live  = pointer_delta(destination, bottom);
1317   const size_t compacted_region_live = pointer_delta(new_top, destination);
1318   const size_t compacted_region_used = pointer_delta(top,
1319                                                      sd.region_to_addr(cp));
1320   const size_t reclaimable = compacted_region_used - compacted_region_live;
1321 
1322   const double divisor = dense_prefix_live + 1.25 * compacted_region_live;
1323   return double(reclaimable) / divisor;
1324 }
1325 
1326 // Return the address of the end of the dense prefix, a.k.a. the start of the
1327 // compacted region.  The address is always on a region boundary.
1328 //
1329 // Completely full regions at the left are skipped, since no compaction can
1330 // occur in those regions.  Then the maximum amount of dead wood to allow is
1331 // computed, based on the density (amount live / capacity) of the generation;
1332 // the region with approximately that amount of dead space to the left is
1333 // identified as the limit region.  Regions between the last completely full
1334 // region and the limit region are scanned and the one that has the best
1335 // (maximum) reclaimed_ratio() is selected.
1336 HeapWord*
1337 PSParallelCompact::compute_dense_prefix(const SpaceId id,
1338                                         bool maximum_compaction)
1339 {
1340   if (ParallelOldGCSplitALot) {
1341     if (_space_info[id].dense_prefix() != _space_info[id].space()->bottom()) {
1342       // The value was chosen to provoke splitting a young gen space; use it.
1343       return _space_info[id].dense_prefix();
1344     }
1345   }
1346 
1347   const size_t region_size = ParallelCompactData::RegionSize;
1348   const ParallelCompactData& sd = summary_data();
1349 
1350   const MutableSpace* const space = _space_info[id].space();
1351   HeapWord* const top = space->top();
1352   HeapWord* const top_aligned_up = sd.region_align_up(top);
1353   HeapWord* const new_top = _space_info[id].new_top();
1354   HeapWord* const new_top_aligned_up = sd.region_align_up(new_top);
1355   HeapWord* const bottom = space->bottom();
1356   const RegionData* const beg_cp = sd.addr_to_region_ptr(bottom);
1357   const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
1358   const RegionData* const new_top_cp =
1359     sd.addr_to_region_ptr(new_top_aligned_up);
1360 
1361   // Skip full regions at the beginning of the space--they are necessarily part
1362   // of the dense prefix.
1363   const RegionData* const full_cp = first_dead_space_region(beg_cp, new_top_cp);
1364   assert(full_cp->destination() == sd.region_to_addr(full_cp) ||
1365          space->is_empty(), "no dead space allowed to the left");
1366   assert(full_cp->data_size() < region_size || full_cp == new_top_cp - 1,
1367          "region must have dead space");
1368 
1369   // The gc number is saved whenever a maximum compaction is done, and used to
1370   // determine when the maximum compaction interval has expired.  This avoids
1371   // successive max compactions for different reasons.
1372   assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");
1373   const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;
1374   const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval ||
1375     total_invocations() == HeapFirstMaximumCompactionCount;
1376   if (maximum_compaction || full_cp == top_cp || interval_ended) {
1377     _maximum_compaction_gc_num = total_invocations();
1378     return sd.region_to_addr(full_cp);
1379   }
1380 
1381   const size_t space_live = pointer_delta(new_top, bottom);
1382   const size_t space_used = space->used_in_words();
1383   const size_t space_capacity = space->capacity_in_words();
1384 
1385   const double density = double(space_live) / double(space_capacity);
1386   const size_t min_percent_free = MarkSweepDeadRatio;
1387   const double limiter = dead_wood_limiter(density, min_percent_free);
1388   const size_t dead_wood_max = space_used - space_live;
1389   const size_t dead_wood_limit = MIN2(size_t(space_capacity * limiter),
1390                                       dead_wood_max);
1391 
1392   if (TraceParallelOldGCDensePrefix) {
1393     tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " "
1394                   "space_cap=" SIZE_FORMAT,
1395                   space_live, space_used,
1396                   space_capacity);
1397     tty->print_cr("dead_wood_limiter(%6.4f, %d)=%6.4f "
1398                   "dead_wood_max=" SIZE_FORMAT " dead_wood_limit=" SIZE_FORMAT,
1399                   density, min_percent_free, limiter,
1400                   dead_wood_max, dead_wood_limit);
1401   }
1402 
1403   // Locate the region with the desired amount of dead space to the left.
1404   const RegionData* const limit_cp =
1405     dead_wood_limit_region(full_cp, top_cp, dead_wood_limit);
1406 
1407   // Scan from the first region with dead space to the limit region and find the
1408   // one with the best (largest) reclaimed ratio.
1409   double best_ratio = 0.0;
1410   const RegionData* best_cp = full_cp;
1411   for (const RegionData* cp = full_cp; cp < limit_cp; ++cp) {
1412     double tmp_ratio = reclaimed_ratio(cp, bottom, top, new_top);
1413     if (tmp_ratio > best_ratio) {
1414       best_cp = cp;
1415       best_ratio = tmp_ratio;
1416     }
1417   }
1418 
1419 #if     0
1420   // Something to consider:  if the region with the best ratio is 'close to' the
1421   // first region w/free space, choose the first region with free space
1422   // ("first-free").  The first-free region is usually near the start of the
1423   // heap, which means we are copying most of the heap already, so copy a bit
1424   // more to get complete compaction.
1425   if (pointer_delta(best_cp, full_cp, sizeof(RegionData)) < 4) {
1426     _maximum_compaction_gc_num = total_invocations();
1427     best_cp = full_cp;
1428   }
1429 #endif  // #if 0
1430 
1431   return sd.region_to_addr(best_cp);
1432 }
1433 
1434 #ifndef PRODUCT
1435 void
1436 PSParallelCompact::fill_with_live_objects(SpaceId id, HeapWord* const start,
1437                                           size_t words)
1438 {
1439   if (TraceParallelOldGCSummaryPhase) {
1440     tty->print_cr("fill_with_live_objects [" PTR_FORMAT " " PTR_FORMAT ") "
1441                   SIZE_FORMAT, start, start + words, words);
1442   }
1443 
1444   ObjectStartArray* const start_array = _space_info[id].start_array();
1445   CollectedHeap::fill_with_objects(start, words);
1446   for (HeapWord* p = start; p < start + words; p += oop(p)->size()) {
1447     _mark_bitmap.mark_obj(p, words);
1448     _summary_data.add_obj(p, words);
1449     start_array->allocate_block(p);
1450   }
1451 }
1452 
1453 void
1454 PSParallelCompact::summarize_new_objects(SpaceId id, HeapWord* start)
1455 {
1456   ParallelCompactData& sd = summary_data();
1457   MutableSpace* space = _space_info[id].space();
1458 
1459   // Find the source and destination start addresses.
1460   HeapWord* const src_addr = sd.region_align_down(start);
1461   HeapWord* dst_addr;
1462   if (src_addr < start) {
1463     dst_addr = sd.addr_to_region_ptr(src_addr)->destination();
1464   } else if (src_addr > space->bottom()) {
1465     // The start (the original top() value) is aligned to a region boundary so
1466     // the associated region does not have a destination.  Compute the
1467     // destination from the previous region.
1468     RegionData* const cp = sd.addr_to_region_ptr(src_addr) - 1;
1469     dst_addr = cp->destination() + cp->data_size();
1470   } else {
1471     // Filling the entire space.
1472     dst_addr = space->bottom();
1473   }
1474   assert(dst_addr != NULL, "sanity");
1475 
1476   // Update the summary data.
1477   bool result = _summary_data.summarize(_space_info[id].split_info(),
1478                                         src_addr, space->top(), NULL,
1479                                         dst_addr, space->end(),
1480                                         _space_info[id].new_top_addr());
1481   assert(result, "should not fail:  bad filler object size");
1482 }
1483 
1484 void
1485 PSParallelCompact::provoke_split_fill_survivor(SpaceId id)
1486 {
1487   if (total_invocations() % (ParallelOldGCSplitInterval * 3) != 0) {
1488     return;
1489   }
1490 
1491   MutableSpace* const space = _space_info[id].space();
1492   if (space->is_empty()) {
1493     HeapWord* b = space->bottom();
1494     HeapWord* t = b + space->capacity_in_words() / 2;
1495     space->set_top(t);
1496     if (ZapUnusedHeapArea) {
1497       space->set_top_for_allocations();
1498     }
1499 
1500     size_t min_size = CollectedHeap::min_fill_size();
1501     size_t obj_len = min_size;
1502     while (b + obj_len <= t) {
1503       CollectedHeap::fill_with_object(b, obj_len);
1504       mark_bitmap()->mark_obj(b, obj_len);
1505       summary_data().add_obj(b, obj_len);
1506       b += obj_len;
1507       obj_len = (obj_len & (min_size*3)) + min_size; // 8 16 24 32 8 16 24 32 ...
1508     }
1509     if (b < t) {
1510       // The loop didn't completely fill to t (top); adjust top downward.
1511       space->set_top(b);
1512       if (ZapUnusedHeapArea) {
1513         space->set_top_for_allocations();
1514       }
1515     }
1516 
1517     HeapWord** nta = _space_info[id].new_top_addr();
1518     bool result = summary_data().summarize(_space_info[id].split_info(),
1519                                            space->bottom(), space->top(), NULL,
1520                                            space->bottom(), space->end(), nta);
1521     assert(result, "space must fit into itself");
1522   }
1523 }
1524 
1525 void
1526 PSParallelCompact::provoke_split(bool & max_compaction)
1527 {
1528   if (total_invocations() % ParallelOldGCSplitInterval != 0) {
1529     return;
1530   }
1531 
1532   const size_t region_size = ParallelCompactData::RegionSize;
1533   ParallelCompactData& sd = summary_data();
1534 
1535   MutableSpace* const eden_space = _space_info[eden_space_id].space();
1536   MutableSpace* const from_space = _space_info[from_space_id].space();
1537   const size_t eden_live = pointer_delta(eden_space->top(),
1538                                          _space_info[eden_space_id].new_top());
1539   const size_t from_live = pointer_delta(from_space->top(),
1540                                          _space_info[from_space_id].new_top());
1541 
1542   const size_t min_fill_size = CollectedHeap::min_fill_size();
1543   const size_t eden_free = pointer_delta(eden_space->end(), eden_space->top());
1544   const size_t eden_fillable = eden_free >= min_fill_size ? eden_free : 0;
1545   const size_t from_free = pointer_delta(from_space->end(), from_space->top());
1546   const size_t from_fillable = from_free >= min_fill_size ? from_free : 0;
1547 
1548   // Choose the space to split; need at least 2 regions live (or fillable).
1549   SpaceId id;
1550   MutableSpace* space;
1551   size_t live_words;
1552   size_t fill_words;
1553   if (eden_live + eden_fillable >= region_size * 2) {
1554     id = eden_space_id;
1555     space = eden_space;
1556     live_words = eden_live;
1557     fill_words = eden_fillable;
1558   } else if (from_live + from_fillable >= region_size * 2) {
1559     id = from_space_id;
1560     space = from_space;
1561     live_words = from_live;
1562     fill_words = from_fillable;
1563   } else {
1564     return; // Give up.
1565   }
1566   assert(fill_words == 0 || fill_words >= min_fill_size, "sanity");
1567 
1568   if (live_words < region_size * 2) {
1569     // Fill from top() to end() w/live objects of mixed sizes.
1570     HeapWord* const fill_start = space->top();
1571     live_words += fill_words;
1572 
1573     space->set_top(fill_start + fill_words);
1574     if (ZapUnusedHeapArea) {
1575       space->set_top_for_allocations();
1576     }
1577 
1578     HeapWord* cur_addr = fill_start;
1579     while (fill_words > 0) {
1580       const size_t r = (size_t)os::random() % (region_size / 2) + min_fill_size;
1581       size_t cur_size = MIN2(align_object_size_(r), fill_words);
1582       if (fill_words - cur_size < min_fill_size) {
1583         cur_size = fill_words; // Avoid leaving a fragment too small to fill.
1584       }
1585 
1586       CollectedHeap::fill_with_object(cur_addr, cur_size);
1587       mark_bitmap()->mark_obj(cur_addr, cur_size);
1588       sd.add_obj(cur_addr, cur_size);
1589 
1590       cur_addr += cur_size;
1591       fill_words -= cur_size;
1592     }
1593 
1594     summarize_new_objects(id, fill_start);
1595   }
1596 
1597   max_compaction = false;
1598 
1599   // Manipulate the old gen so that it has room for about half of the live data
1600   // in the target young gen space (live_words / 2).
1601   id = old_space_id;
1602   space = _space_info[id].space();
1603   const size_t free_at_end = space->free_in_words();
1604   const size_t free_target = align_object_size(live_words / 2);
1605   const size_t dead = pointer_delta(space->top(), _space_info[id].new_top());
1606 
1607   if (free_at_end >= free_target + min_fill_size) {
1608     // Fill space above top() and set the dense prefix so everything survives.
1609     HeapWord* const fill_start = space->top();
1610     const size_t fill_size = free_at_end - free_target;
1611     space->set_top(space->top() + fill_size);
1612     if (ZapUnusedHeapArea) {
1613       space->set_top_for_allocations();
1614     }
1615     fill_with_live_objects(id, fill_start, fill_size);
1616     summarize_new_objects(id, fill_start);
1617     _space_info[id].set_dense_prefix(sd.region_align_down(space->top()));
1618   } else if (dead + free_at_end > free_target) {
1619     // Find a dense prefix that makes the right amount of space available.
1620     HeapWord* cur = sd.region_align_down(space->top());
1621     HeapWord* cur_destination = sd.addr_to_region_ptr(cur)->destination();
1622     size_t dead_to_right = pointer_delta(space->end(), cur_destination);
1623     while (dead_to_right < free_target) {
1624       cur -= region_size;
1625       cur_destination = sd.addr_to_region_ptr(cur)->destination();
1626       dead_to_right = pointer_delta(space->end(), cur_destination);
1627     }
1628     _space_info[id].set_dense_prefix(cur);
1629   }
1630 }
1631 #endif // #ifndef PRODUCT
1632 
1633 void PSParallelCompact::summarize_spaces_quick()
1634 {
1635   for (unsigned int i = 0; i < last_space_id; ++i) {
1636     const MutableSpace* space = _space_info[i].space();
1637     HeapWord** nta = _space_info[i].new_top_addr();
1638     bool result = _summary_data.summarize(_space_info[i].split_info(),
1639                                           space->bottom(), space->top(), NULL,
1640                                           space->bottom(), space->end(), nta);
1641     assert(result, "space must fit into itself");
1642     _space_info[i].set_dense_prefix(space->bottom());
1643   }
1644 
1645 #ifndef PRODUCT
1646   if (ParallelOldGCSplitALot) {
1647     provoke_split_fill_survivor(to_space_id);
1648   }
1649 #endif // #ifndef PRODUCT
1650 }
1651 
1652 void PSParallelCompact::fill_dense_prefix_end(SpaceId id)
1653 {
1654   HeapWord* const dense_prefix_end = dense_prefix(id);
1655   const RegionData* region = _summary_data.addr_to_region_ptr(dense_prefix_end);
1656   const idx_t dense_prefix_bit = _mark_bitmap.addr_to_bit(dense_prefix_end);
1657   if (dead_space_crosses_boundary(region, dense_prefix_bit)) {
1658     // Only enough dead space is filled so that any remaining dead space to the
1659     // left is larger than the minimum filler object.  (The remainder is filled
1660     // during the copy/update phase.)
1661     //
1662     // The size of the dead space to the right of the boundary is not a
1663     // concern, since compaction will be able to use whatever space is
1664     // available.
1665     //
1666     // Here '||' is the boundary, 'x' represents a don't care bit and a box
1667     // surrounds the space to be filled with an object.
1668     //
1669     // In the 32-bit VM, each bit represents two 32-bit words:
1670     //                              +---+
1671     // a) beg_bits:  ...  x   x   x | 0 | ||   0   x  x  ...
1672     //    end_bits:  ...  x   x   x | 0 | ||   0   x  x  ...
1673     //                              +---+
1674     //
1675     // In the 64-bit VM, each bit represents one 64-bit word:
1676     //                              +------------+
1677     // b) beg_bits:  ...  x   x   x | 0   ||   0 | x  x  ...
1678     //    end_bits:  ...  x   x   1 | 0   ||   0 | x  x  ...
1679     //                              +------------+
1680     //                          +-------+
1681     // c) beg_bits:  ...  x   x | 0   0 | ||   0   x  x  ...
1682     //    end_bits:  ...  x   1 | 0   0 | ||   0   x  x  ...
1683     //                          +-------+
1684     //                      +-----------+
1685     // d) beg_bits:  ...  x | 0   0   0 | ||   0   x  x  ...
1686     //    end_bits:  ...  1 | 0   0   0 | ||   0   x  x  ...
1687     //                      +-----------+
1688     //                          +-------+
1689     // e) beg_bits:  ...  0   0 | 0   0 | ||   0   x  x  ...
1690     //    end_bits:  ...  0   0 | 0   0 | ||   0   x  x  ...
1691     //                          +-------+
1692 
1693     // Initially assume case a, c or e will apply.
1694     size_t obj_len = CollectedHeap::min_fill_size();
1695     HeapWord* obj_beg = dense_prefix_end - obj_len;
1696 
1697 #ifdef  _LP64
1698     if (MinObjAlignment > 1) { // object alignment > heap word size
1699       // Cases a, c or e.
1700     } else if (_mark_bitmap.is_obj_end(dense_prefix_bit - 2)) {
1701       // Case b above.
1702       obj_beg = dense_prefix_end - 1;
1703     } else if (!_mark_bitmap.is_obj_end(dense_prefix_bit - 3) &&
1704                _mark_bitmap.is_obj_end(dense_prefix_bit - 4)) {
1705       // Case d above.
1706       obj_beg = dense_prefix_end - 3;
1707       obj_len = 3;
1708     }
1709 #endif  // #ifdef _LP64
1710 
1711     CollectedHeap::fill_with_object(obj_beg, obj_len);
1712     _mark_bitmap.mark_obj(obj_beg, obj_len);
1713     _summary_data.add_obj(obj_beg, obj_len);
1714     assert(start_array(id) != NULL, "sanity");
1715     start_array(id)->allocate_block(obj_beg);
1716   }
1717 }
1718 
1719 void
1720 PSParallelCompact::clear_source_region(HeapWord* beg_addr, HeapWord* end_addr)
1721 {
1722   RegionData* const beg_ptr = _summary_data.addr_to_region_ptr(beg_addr);
1723   HeapWord* const end_aligned_up = _summary_data.region_align_up(end_addr);
1724   RegionData* const end_ptr = _summary_data.addr_to_region_ptr(end_aligned_up);
1725   for (RegionData* cur = beg_ptr; cur < end_ptr; ++cur) {
1726     cur->set_source_region(0);
1727   }
1728 }
1729 
1730 void
1731 PSParallelCompact::summarize_space(SpaceId id, bool maximum_compaction)
1732 {
1733   assert(id < last_space_id, "id out of range");
1734   assert(_space_info[id].dense_prefix() == _space_info[id].space()->bottom() ||
1735          ParallelOldGCSplitALot && id == old_space_id,
1736          "should have been reset in summarize_spaces_quick()");
1737 
1738   const MutableSpace* space = _space_info[id].space();
1739   if (_space_info[id].new_top() != space->bottom()) {
1740     HeapWord* dense_prefix_end = compute_dense_prefix(id, maximum_compaction);
1741     _space_info[id].set_dense_prefix(dense_prefix_end);
1742 
1743 #ifndef PRODUCT
1744     if (TraceParallelOldGCDensePrefix) {
1745       print_dense_prefix_stats("ratio", id, maximum_compaction,
1746                                dense_prefix_end);
1747       HeapWord* addr = compute_dense_prefix_via_density(id, maximum_compaction);
1748       print_dense_prefix_stats("density", id, maximum_compaction, addr);
1749     }
1750 #endif  // #ifndef PRODUCT
1751 
1752     // Recompute the summary data, taking into account the dense prefix.  If
1753     // every last byte will be reclaimed, then the existing summary data which
1754     // compacts everything can be left in place.
1755     if (!maximum_compaction && dense_prefix_end != space->bottom()) {
1756       // If dead space crosses the dense prefix boundary, it is (at least
1757       // partially) filled with a dummy object, marked live and added to the
1758       // summary data.  This simplifies the copy/update phase and must be done
1759       // before the final locations of objects are determined, to prevent
1760       // leaving a fragment of dead space that is too small to fill.
1761       fill_dense_prefix_end(id);
1762 
1763       // Compute the destination of each Region, and thus each object.
1764       _summary_data.summarize_dense_prefix(space->bottom(), dense_prefix_end);
1765       _summary_data.summarize(_space_info[id].split_info(),
1766                               dense_prefix_end, space->top(), NULL,
1767                               dense_prefix_end, space->end(),
1768                               _space_info[id].new_top_addr());
1769     }
1770   }
1771 
1772   if (TraceParallelOldGCSummaryPhase) {
1773     const size_t region_size = ParallelCompactData::RegionSize;
1774     HeapWord* const dense_prefix_end = _space_info[id].dense_prefix();
1775     const size_t dp_region = _summary_data.addr_to_region_idx(dense_prefix_end);
1776     const size_t dp_words = pointer_delta(dense_prefix_end, space->bottom());
1777     HeapWord* const new_top = _space_info[id].new_top();
1778     const HeapWord* nt_aligned_up = _summary_data.region_align_up(new_top);
1779     const size_t cr_words = pointer_delta(nt_aligned_up, dense_prefix_end);
1780     tty->print_cr("id=%d cap=" SIZE_FORMAT " dp=" PTR_FORMAT " "
1781                   "dp_region=" SIZE_FORMAT " " "dp_count=" SIZE_FORMAT " "
1782                   "cr_count=" SIZE_FORMAT " " "nt=" PTR_FORMAT,
1783                   id, space->capacity_in_words(), dense_prefix_end,
1784                   dp_region, dp_words / region_size,
1785                   cr_words / region_size, new_top);
1786   }
1787 }
1788 
1789 #ifndef PRODUCT
1790 void PSParallelCompact::summary_phase_msg(SpaceId dst_space_id,
1791                                           HeapWord* dst_beg, HeapWord* dst_end,
1792                                           SpaceId src_space_id,
1793                                           HeapWord* src_beg, HeapWord* src_end)
1794 {
1795   if (TraceParallelOldGCSummaryPhase) {
1796     tty->print_cr("summarizing %d [%s] into %d [%s]:  "
1797                   "src=" PTR_FORMAT "-" PTR_FORMAT " "
1798                   SIZE_FORMAT "-" SIZE_FORMAT " "
1799                   "dst=" PTR_FORMAT "-" PTR_FORMAT " "
1800                   SIZE_FORMAT "-" SIZE_FORMAT,
1801                   src_space_id, space_names[src_space_id],
1802                   dst_space_id, space_names[dst_space_id],
1803                   src_beg, src_end,
1804                   _summary_data.addr_to_region_idx(src_beg),
1805                   _summary_data.addr_to_region_idx(src_end),
1806                   dst_beg, dst_end,
1807                   _summary_data.addr_to_region_idx(dst_beg),
1808                   _summary_data.addr_to_region_idx(dst_end));
1809   }
1810 }
1811 #endif  // #ifndef PRODUCT
1812 
1813 void PSParallelCompact::summary_phase(ParCompactionManager* cm,
1814                                       bool maximum_compaction)
1815 {
1816   TraceTime tm("summary phase", print_phases(), true, gclog_or_tty);
1817   // trace("2");
1818 
1819 #ifdef  ASSERT
1820   if (TraceParallelOldGCMarkingPhase) {
1821     tty->print_cr("add_obj_count=" SIZE_FORMAT " "
1822                   "add_obj_bytes=" SIZE_FORMAT,
1823                   add_obj_count, add_obj_size * HeapWordSize);
1824     tty->print_cr("mark_bitmap_count=" SIZE_FORMAT " "
1825                   "mark_bitmap_bytes=" SIZE_FORMAT,
1826                   mark_bitmap_count, mark_bitmap_size * HeapWordSize);
1827   }
1828 #endif  // #ifdef ASSERT
1829 
1830   // Quick summarization of each space into itself, to see how much is live.
1831   summarize_spaces_quick();
1832 
1833   if (TraceParallelOldGCSummaryPhase) {
1834     tty->print_cr("summary_phase:  after summarizing each space to self");
1835     Universe::print();
1836     NOT_PRODUCT(print_region_ranges());
1837     if (Verbose) {
1838       NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info));
1839     }
1840   }
1841 
1842   // The amount of live data that will end up in old space (assuming it fits).
1843   size_t old_space_total_live = 0;
1844   for (unsigned int id = old_space_id; id < last_space_id; ++id) {
1845     old_space_total_live += pointer_delta(_space_info[id].new_top(),
1846                                           _space_info[id].space()->bottom());
1847   }
1848 
1849   MutableSpace* const old_space = _space_info[old_space_id].space();
1850   const size_t old_capacity = old_space->capacity_in_words();
1851   if (old_space_total_live > old_capacity) {
1852     // XXX - should also try to expand
1853     maximum_compaction = true;
1854   }
1855 #ifndef PRODUCT
1856   if (ParallelOldGCSplitALot && old_space_total_live < old_capacity) {
1857     provoke_split(maximum_compaction);
1858   }
1859 #endif // #ifndef PRODUCT
1860 
1861   // Old generations.
1862   summarize_space(old_space_id, maximum_compaction);
1863 
1864   // Summarize the remaining spaces in the young gen.  The initial target space
1865   // is the old gen.  If a space does not fit entirely into the target, then the
1866   // remainder is compacted into the space itself and that space becomes the new
1867   // target.
1868   SpaceId dst_space_id = old_space_id;
1869   HeapWord* dst_space_end = old_space->end();
1870   HeapWord** new_top_addr = _space_info[dst_space_id].new_top_addr();
1871   for (unsigned int id = eden_space_id; id < last_space_id; ++id) {
1872     const MutableSpace* space = _space_info[id].space();
1873     const size_t live = pointer_delta(_space_info[id].new_top(),
1874                                       space->bottom());
1875     const size_t available = pointer_delta(dst_space_end, *new_top_addr);
1876 
1877     NOT_PRODUCT(summary_phase_msg(dst_space_id, *new_top_addr, dst_space_end,
1878                                   SpaceId(id), space->bottom(), space->top());)
1879     if (live > 0 && live <= available) {
1880       // All the live data will fit.
1881       bool done = _summary_data.summarize(_space_info[id].split_info(),
1882                                           space->bottom(), space->top(),
1883                                           NULL,
1884                                           *new_top_addr, dst_space_end,
1885                                           new_top_addr);
1886       assert(done, "space must fit into old gen");
1887 
1888       // Reset the new_top value for the space.
1889       _space_info[id].set_new_top(space->bottom());
1890     } else if (live > 0) {
1891       // Attempt to fit part of the source space into the target space.
1892       HeapWord* next_src_addr = NULL;
1893       bool done = _summary_data.summarize(_space_info[id].split_info(),
1894                                           space->bottom(), space->top(),
1895                                           &next_src_addr,
1896                                           *new_top_addr, dst_space_end,
1897                                           new_top_addr);
1898       assert(!done, "space should not fit into old gen");
1899       assert(next_src_addr != NULL, "sanity");
1900 
1901       // The source space becomes the new target, so the remainder is compacted
1902       // within the space itself.
1903       dst_space_id = SpaceId(id);
1904       dst_space_end = space->end();
1905       new_top_addr = _space_info[id].new_top_addr();
1906       NOT_PRODUCT(summary_phase_msg(dst_space_id,
1907                                     space->bottom(), dst_space_end,
1908                                     SpaceId(id), next_src_addr, space->top());)
1909       done = _summary_data.summarize(_space_info[id].split_info(),
1910                                      next_src_addr, space->top(),
1911                                      NULL,
1912                                      space->bottom(), dst_space_end,
1913                                      new_top_addr);
1914       assert(done, "space must fit when compacted into itself");
1915       assert(*new_top_addr <= space->top(), "usage should not grow");
1916     }
1917   }
1918 
1919   if (TraceParallelOldGCSummaryPhase) {
1920     tty->print_cr("summary_phase:  after final summarization");
1921     Universe::print();
1922     NOT_PRODUCT(print_region_ranges());
1923     if (Verbose) {
1924       NOT_PRODUCT(print_generic_summary_data(_summary_data, _space_info));
1925     }
1926   }
1927 }
1928 
1929 // This method should contain all heap-specific policy for invoking a full
1930 // collection.  invoke_no_policy() will only attempt to compact the heap; it
1931 // will do nothing further.  If we need to bail out for policy reasons, scavenge
1932 // before full gc, or any other specialized behavior, it needs to be added here.
1933 //
1934 // Note that this method should only be called from the vm_thread while at a
1935 // safepoint.
1936 //
1937 // Note that the all_soft_refs_clear flag in the collector policy
1938 // may be true because this method can be called without intervening
1939 // activity.  For example when the heap space is tight and full measure
1940 // are being taken to free space.
1941 void PSParallelCompact::invoke(bool maximum_heap_compaction) {
1942   assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
1943   assert(Thread::current() == (Thread*)VMThread::vm_thread(),
1944          "should be in vm thread");
1945 
1946   ParallelScavengeHeap* heap = gc_heap();
1947   GCCause::Cause gc_cause = heap->gc_cause();
1948   assert(!heap->is_gc_active(), "not reentrant");
1949 
1950   PSAdaptiveSizePolicy* policy = heap->size_policy();
1951   IsGCActiveMark mark;
1952 
1953   if (ScavengeBeforeFullGC) {
1954     PSScavenge::invoke_no_policy();
1955   }
1956 
1957   const bool clear_all_soft_refs =
1958     heap->collector_policy()->should_clear_all_soft_refs();
1959 
1960   PSParallelCompact::invoke_no_policy(clear_all_soft_refs ||
1961                                       maximum_heap_compaction);
1962 }
1963 
1964 bool ParallelCompactData::region_contains(size_t region_index, HeapWord* addr) {
1965   size_t addr_region_index = addr_to_region_idx(addr);
1966   return region_index == addr_region_index;
1967 }
1968 
1969 // This method contains no policy. You should probably
1970 // be calling invoke() instead.
1971 bool PSParallelCompact::invoke_no_policy(bool maximum_heap_compaction) {
1972   assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
1973   assert(ref_processor() != NULL, "Sanity");
1974 
1975   if (GC_locker::check_active_before_gc()) {
1976     return false;
1977   }
1978 
1979   TimeStamp marking_start;
1980   TimeStamp compaction_start;
1981   TimeStamp collection_exit;
1982 
1983   ParallelScavengeHeap* heap = gc_heap();
1984   GCCause::Cause gc_cause = heap->gc_cause();
1985   PSYoungGen* young_gen = heap->young_gen();
1986   PSOldGen* old_gen = heap->old_gen();
1987   PSAdaptiveSizePolicy* size_policy = heap->size_policy();
1988 
1989   // The scope of casr should end after code that can change
1990   // CollectorPolicy::_should_clear_all_soft_refs.
1991   ClearedAllSoftRefs casr(maximum_heap_compaction,
1992                           heap->collector_policy());
1993 
1994   if (ZapUnusedHeapArea) {
1995     // Save information needed to minimize mangling
1996     heap->record_gen_tops_before_GC();
1997   }
1998 
1999   heap->pre_full_gc_dump();
2000 
2001   _print_phases = PrintGCDetails && PrintParallelOldGCPhaseTimes;
2002 
2003   // Make sure data structures are sane, make the heap parsable, and do other
2004   // miscellaneous bookkeeping.
2005   PreGCValues pre_gc_values;
2006   pre_compact(&pre_gc_values);
2007 
2008   // Get the compaction manager reserved for the VM thread.
2009   ParCompactionManager* const vmthread_cm =
2010     ParCompactionManager::manager_array(gc_task_manager()->workers());
2011 
2012   // Place after pre_compact() where the number of invocations is incremented.
2013   AdaptiveSizePolicyOutput(size_policy, heap->total_collections());
2014 
2015   {
2016     ResourceMark rm;
2017     HandleMark hm;
2018 
2019     // Set the number of GC threads to be used in this collection
2020     gc_task_manager()->set_active_gang();
2021     gc_task_manager()->task_idle_workers();
2022     heap->set_par_threads(gc_task_manager()->active_workers());
2023 
2024     gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
2025     TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
2026     TraceTime t1(GCCauseString("Full GC", gc_cause), PrintGC, !PrintGCDetails, gclog_or_tty);
2027     TraceCollectorStats tcs(counters());
2028     TraceMemoryManagerStats tms(true /* Full GC */,gc_cause);
2029 
2030     if (TraceGen1Time) accumulated_time()->start();
2031 
2032     // Let the size policy know we're starting
2033     size_policy->major_collection_begin();
2034 
2035     CodeCache::gc_prologue();
2036     Threads::gc_prologue();
2037 
2038     COMPILER2_PRESENT(DerivedPointerTable::clear());
2039 
2040     ref_processor()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
2041     ref_processor()->setup_policy(maximum_heap_compaction);
2042 
2043     bool marked_for_unloading = false;
2044 
2045     marking_start.update();
2046     marking_phase(vmthread_cm, maximum_heap_compaction);
2047 
2048     bool max_on_system_gc = UseMaximumCompactionOnSystemGC
2049       && gc_cause == GCCause::_java_lang_system_gc;
2050     summary_phase(vmthread_cm, maximum_heap_compaction || max_on_system_gc);
2051 
2052     COMPILER2_PRESENT(assert(DerivedPointerTable::is_active(), "Sanity"));
2053     COMPILER2_PRESENT(DerivedPointerTable::set_active(false));
2054 
2055     // adjust_roots() updates Universe::_intArrayKlassObj which is
2056     // needed by the compaction for filling holes in the dense prefix.
2057     adjust_roots();
2058 
2059     compaction_start.update();
2060     compact();
2061 
2062     // Reset the mark bitmap, summary data, and do other bookkeeping.  Must be
2063     // done before resizing.
2064     post_compact();
2065 
2066     // Let the size policy know we're done
2067     size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause);
2068 
2069     if (UseAdaptiveSizePolicy) {
2070       if (PrintAdaptiveSizePolicy) {
2071         gclog_or_tty->print("AdaptiveSizeStart: ");
2072         gclog_or_tty->stamp();
2073         gclog_or_tty->print_cr(" collection: %d ",
2074                        heap->total_collections());
2075         if (Verbose) {
2076           gclog_or_tty->print("old_gen_capacity: %d young_gen_capacity: %d",
2077             old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes());
2078         }
2079       }
2080 
2081       // Don't check if the size_policy is ready here.  Let
2082       // the size_policy check that internally.
2083       if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&
2084           ((gc_cause != GCCause::_java_lang_system_gc) ||
2085             UseAdaptiveSizePolicyWithSystemGC)) {
2086         // Calculate optimal free space amounts
2087         assert(young_gen->max_size() >
2088           young_gen->from_space()->capacity_in_bytes() +
2089           young_gen->to_space()->capacity_in_bytes(),
2090           "Sizes of space in young gen are out-of-bounds");
2091 
2092         size_t young_live = young_gen->used_in_bytes();
2093         size_t eden_live = young_gen->eden_space()->used_in_bytes();
2094         size_t old_live = old_gen->used_in_bytes();
2095         size_t cur_eden = young_gen->eden_space()->capacity_in_bytes();
2096         size_t max_old_gen_size = old_gen->max_gen_size();
2097         size_t max_eden_size = young_gen->max_size() -
2098           young_gen->from_space()->capacity_in_bytes() -
2099           young_gen->to_space()->capacity_in_bytes();
2100 
2101         // Used for diagnostics
2102         size_policy->clear_generation_free_space_flags();
2103 
2104         size_policy->compute_generations_free_space(young_live,
2105                                                     eden_live,
2106                                                     old_live,
2107                                                     cur_eden,
2108                                                     max_old_gen_size,
2109                                                     max_eden_size,
2110                                                     true /* full gc*/);
2111 
2112         size_policy->check_gc_overhead_limit(young_live,
2113                                              eden_live,
2114                                              max_old_gen_size,
2115                                              max_eden_size,
2116                                              true /* full gc*/,
2117                                              gc_cause,
2118                                              heap->collector_policy());
2119 
2120         size_policy->decay_supplemental_growth(true /* full gc*/);
2121 
2122         heap->resize_old_gen(
2123           size_policy->calculated_old_free_size_in_bytes());
2124 
2125         // Don't resize the young generation at an major collection.  A
2126         // desired young generation size may have been calculated but
2127         // resizing the young generation complicates the code because the
2128         // resizing of the old generation may have moved the boundary
2129         // between the young generation and the old generation.  Let the
2130         // young generation resizing happen at the minor collections.
2131       }
2132       if (PrintAdaptiveSizePolicy) {
2133         gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ",
2134                        heap->total_collections());
2135       }
2136     }
2137 
2138     if (UsePerfData) {
2139       PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters();
2140       counters->update_counters();
2141       counters->update_old_capacity(old_gen->capacity_in_bytes());
2142       counters->update_young_capacity(young_gen->capacity_in_bytes());
2143     }
2144 
2145     heap->resize_all_tlabs();
2146 
2147     // Resize the metaspace capactiy after a collection
2148     MetaspaceGC::compute_new_size();
2149 
2150     if (TraceGen1Time) accumulated_time()->stop();
2151 
2152     if (PrintGC) {
2153       if (PrintGCDetails) {
2154         // No GC timestamp here.  This is after GC so it would be confusing.
2155         young_gen->print_used_change(pre_gc_values.young_gen_used());
2156         old_gen->print_used_change(pre_gc_values.old_gen_used());
2157         heap->print_heap_change(pre_gc_values.heap_used());
2158         MetaspaceAux::print_metaspace_change(pre_gc_values.metadata_used());
2159       } else {
2160         heap->print_heap_change(pre_gc_values.heap_used());
2161       }
2162     }
2163 
2164     // Track memory usage and detect low memory
2165     MemoryService::track_memory_usage();
2166     heap->update_counters();
2167     gc_task_manager()->release_idle_workers();
2168   }
2169 
2170 #ifdef ASSERT
2171   for (size_t i = 0; i < ParallelGCThreads + 1; ++i) {
2172     ParCompactionManager* const cm =
2173       ParCompactionManager::manager_array(int(i));
2174     assert(cm->marking_stack()->is_empty(),       "should be empty");
2175     assert(ParCompactionManager::region_list(int(i))->is_empty(), "should be empty");
2176   }
2177 #endif // ASSERT
2178 
2179   if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
2180     HandleMark hm;  // Discard invalid handles created during verification
2181     Universe::verify(" VerifyAfterGC:");
2182   }
2183 
2184   // Re-verify object start arrays
2185   if (VerifyObjectStartArray &&
2186       VerifyAfterGC) {
2187     old_gen->verify_object_start_array();
2188   }
2189 
2190   if (ZapUnusedHeapArea) {
2191     old_gen->object_space()->check_mangled_unused_area_complete();
2192   }
2193 
2194   NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
2195 
2196   collection_exit.update();
2197 
2198   heap->print_heap_after_gc();
2199   if (PrintGCTaskTimeStamps) {
2200     gclog_or_tty->print_cr("VM-Thread " INT64_FORMAT " " INT64_FORMAT " "
2201                            INT64_FORMAT,
2202                            marking_start.ticks(), compaction_start.ticks(),
2203                            collection_exit.ticks());
2204     gc_task_manager()->print_task_time_stamps();
2205   }
2206 
2207   heap->post_full_gc_dump();
2208 
2209 #ifdef TRACESPINNING
2210   ParallelTaskTerminator::print_termination_counts();
2211 #endif
2212 
2213   return true;
2214 }
2215 
2216 bool PSParallelCompact::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
2217                                              PSYoungGen* young_gen,
2218                                              PSOldGen* old_gen) {
2219   MutableSpace* const eden_space = young_gen->eden_space();
2220   assert(!eden_space->is_empty(), "eden must be non-empty");
2221   assert(young_gen->virtual_space()->alignment() ==
2222          old_gen->virtual_space()->alignment(), "alignments do not match");
2223 
2224   if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) {
2225     return false;
2226   }
2227 
2228   // Both generations must be completely committed.
2229   if (young_gen->virtual_space()->uncommitted_size() != 0) {
2230     return false;
2231   }
2232   if (old_gen->virtual_space()->uncommitted_size() != 0) {
2233     return false;
2234   }
2235 
2236   // Figure out how much to take from eden.  Include the average amount promoted
2237   // in the total; otherwise the next young gen GC will simply bail out to a
2238   // full GC.
2239   const size_t alignment = old_gen->virtual_space()->alignment();
2240   const size_t eden_used = eden_space->used_in_bytes();
2241   const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average();
2242   const size_t absorb_size = align_size_up(eden_used + promoted, alignment);
2243   const size_t eden_capacity = eden_space->capacity_in_bytes();
2244 
2245   if (absorb_size >= eden_capacity) {
2246     return false; // Must leave some space in eden.
2247   }
2248 
2249   const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size;
2250   if (new_young_size < young_gen->min_gen_size()) {
2251     return false; // Respect young gen minimum size.
2252   }
2253 
2254   if (TraceAdaptiveGCBoundary && Verbose) {
2255     gclog_or_tty->print(" absorbing " SIZE_FORMAT "K:  "
2256                         "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K "
2257                         "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K "
2258                         "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ",
2259                         absorb_size / K,
2260                         eden_capacity / K, (eden_capacity - absorb_size) / K,
2261                         young_gen->from_space()->used_in_bytes() / K,
2262                         young_gen->to_space()->used_in_bytes() / K,
2263                         young_gen->capacity_in_bytes() / K, new_young_size / K);
2264   }
2265 
2266   // Fill the unused part of the old gen.
2267   MutableSpace* const old_space = old_gen->object_space();
2268   HeapWord* const unused_start = old_space->top();
2269   size_t const unused_words = pointer_delta(old_space->end(), unused_start);
2270 
2271   if (unused_words > 0) {
2272     if (unused_words < CollectedHeap::min_fill_size()) {
2273       return false;  // If the old gen cannot be filled, must give up.
2274     }
2275     CollectedHeap::fill_with_objects(unused_start, unused_words);
2276   }
2277 
2278   // Take the live data from eden and set both top and end in the old gen to
2279   // eden top.  (Need to set end because reset_after_change() mangles the region
2280   // from end to virtual_space->high() in debug builds).
2281   HeapWord* const new_top = eden_space->top();
2282   old_gen->virtual_space()->expand_into(young_gen->virtual_space(),
2283                                         absorb_size);
2284   young_gen->reset_after_change();
2285   old_space->set_top(new_top);
2286   old_space->set_end(new_top);
2287   old_gen->reset_after_change();
2288 
2289   // Update the object start array for the filler object and the data from eden.
2290   ObjectStartArray* const start_array = old_gen->start_array();
2291   for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) {
2292     start_array->allocate_block(p);
2293   }
2294 
2295   // Could update the promoted average here, but it is not typically updated at
2296   // full GCs and the value to use is unclear.  Something like
2297   //
2298   // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc.
2299 
2300   size_policy->set_bytes_absorbed_from_eden(absorb_size);
2301   return true;
2302 }
2303 
2304 GCTaskManager* const PSParallelCompact::gc_task_manager() {
2305   assert(ParallelScavengeHeap::gc_task_manager() != NULL,
2306     "shouldn't return NULL");
2307   return ParallelScavengeHeap::gc_task_manager();
2308 }
2309 
2310 void PSParallelCompact::marking_phase(ParCompactionManager* cm,
2311                                       bool maximum_heap_compaction) {
2312   // Recursively traverse all live objects and mark them
2313   TraceTime tm("marking phase", print_phases(), true, gclog_or_tty);
2314 
2315   ParallelScavengeHeap* heap = gc_heap();
2316   uint parallel_gc_threads = heap->gc_task_manager()->workers();
2317   uint active_gc_threads = heap->gc_task_manager()->active_workers();
2318   TaskQueueSetSuper* qset = ParCompactionManager::region_array();
2319   ParallelTaskTerminator terminator(active_gc_threads, qset);
2320 
2321   PSParallelCompact::MarkAndPushClosure mark_and_push_closure(cm);
2322   PSParallelCompact::FollowStackClosure follow_stack_closure(cm);
2323 
2324   // Need new claim bits before marking starts.
2325   ClassLoaderDataGraph::clear_claimed_marks();
2326 
2327   {
2328     TraceTime tm_m("par mark", print_phases(), true, gclog_or_tty);
2329     ParallelScavengeHeap::ParStrongRootsScope psrs;
2330 
2331     GCTaskQueue* q = GCTaskQueue::create();
2332 
2333     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::universe));
2334     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jni_handles));
2335     // We scan the thread roots in parallel
2336     Threads::create_thread_roots_marking_tasks(q);
2337     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::object_synchronizer));
2338     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::flat_profiler));
2339     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::management));
2340     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::system_dictionary));
2341     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::class_loader_data));
2342     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jvmti));
2343     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::code_cache));
2344 
2345     if (active_gc_threads > 1) {
2346       for (uint j = 0; j < active_gc_threads; j++) {
2347         q->enqueue(new StealMarkingTask(&terminator));
2348       }
2349     }
2350 
2351     gc_task_manager()->execute_and_wait(q);
2352   }
2353 
2354   // Process reference objects found during marking
2355   {
2356     TraceTime tm_r("reference processing", print_phases(), true, gclog_or_tty);
2357     if (ref_processor()->processing_is_mt()) {
2358       RefProcTaskExecutor task_executor;
2359       ref_processor()->process_discovered_references(
2360         is_alive_closure(), &mark_and_push_closure, &follow_stack_closure,
2361         &task_executor);
2362     } else {
2363       ref_processor()->process_discovered_references(
2364         is_alive_closure(), &mark_and_push_closure, &follow_stack_closure, NULL);
2365     }
2366   }
2367 
2368   TraceTime tm_c("class unloading", print_phases(), true, gclog_or_tty);
2369 
2370   // This is the point where the entire marking should have completed.
2371   assert(cm->marking_stacks_empty(), "Marking should have completed");
2372 
2373   // Follow system dictionary roots and unload classes.
2374   bool purged_class = SystemDictionary::do_unloading(is_alive_closure());
2375 
2376   // Unload nmethods.
2377   CodeCache::do_unloading(is_alive_closure(), purged_class);
2378 
2379   // Prune dead klasses from subklass/sibling/implementor lists.
2380   Klass::clean_weak_klass_links(is_alive_closure());
2381 
2382   // Delete entries for dead interned strings.
2383   StringTable::unlink(is_alive_closure());
2384 
2385   // Clean up unreferenced symbols in symbol table.
2386   SymbolTable::unlink();
2387 }
2388 
2389 void PSParallelCompact::follow_klass(ParCompactionManager* cm, Klass* klass) {
2390   ClassLoaderData* cld = klass->class_loader_data();
2391   // The actual processing of the klass is done when we
2392   // traverse the list of Klasses in the class loader data.
2393   PSParallelCompact::follow_class_loader(cm, cld);
2394 }
2395 
2396 void PSParallelCompact::adjust_klass(ParCompactionManager* cm, Klass* klass) {
2397   ClassLoaderData* cld = klass->class_loader_data();
2398   // The actual processing of the klass is done when we
2399   // traverse the list of Klasses in the class loader data.
2400   PSParallelCompact::adjust_class_loader(cm, cld);
2401 }
2402 
2403 void PSParallelCompact::follow_class_loader(ParCompactionManager* cm,
2404                                             ClassLoaderData* cld) {
2405   PSParallelCompact::MarkAndPushClosure mark_and_push_closure(cm);
2406   PSParallelCompact::FollowKlassClosure follow_klass_closure(&mark_and_push_closure);
2407 
2408   cld->oops_do(&mark_and_push_closure, &follow_klass_closure, true);
2409 }
2410 
2411 void PSParallelCompact::adjust_class_loader(ParCompactionManager* cm,
2412                                             ClassLoaderData* cld) {
2413   cld->oops_do(PSParallelCompact::adjust_pointer_closure(),
2414                PSParallelCompact::adjust_klass_closure(),
2415                true);
2416 }
2417 
2418 // This should be moved to the shared markSweep code!
2419 class PSAlwaysTrueClosure: public BoolObjectClosure {
2420 public:
2421   bool do_object_b(oop p) { return true; }
2422 };
2423 static PSAlwaysTrueClosure always_true;
2424 
2425 void PSParallelCompact::adjust_roots() {
2426   // Adjust the pointers to reflect the new locations
2427   TraceTime tm("adjust roots", print_phases(), true, gclog_or_tty);
2428 
2429   // Need new claim bits when tracing through and adjusting pointers.
2430   ClassLoaderDataGraph::clear_claimed_marks();
2431 
2432   // General strong roots.
2433   Universe::oops_do(adjust_pointer_closure());
2434   JNIHandles::oops_do(adjust_pointer_closure());   // Global (strong) JNI handles
2435   CLDToOopClosure adjust_from_cld(adjust_pointer_closure());
2436   Threads::oops_do(adjust_pointer_closure(), &adjust_from_cld, NULL);
2437   ObjectSynchronizer::oops_do(adjust_pointer_closure());
2438   FlatProfiler::oops_do(adjust_pointer_closure());
2439   Management::oops_do(adjust_pointer_closure());
2440   JvmtiExport::oops_do(adjust_pointer_closure());
2441   // SO_AllClasses
2442   SystemDictionary::oops_do(adjust_pointer_closure());
2443   ClassLoaderDataGraph::oops_do(adjust_pointer_closure(), adjust_klass_closure(), true);
2444 
2445   // Now adjust pointers in remaining weak roots.  (All of which should
2446   // have been cleared if they pointed to non-surviving objects.)
2447   // Global (weak) JNI handles
2448   JNIHandles::weak_oops_do(&always_true, adjust_pointer_closure());
2449 
2450   CodeCache::oops_do(adjust_pointer_closure());
2451   StringTable::oops_do(adjust_pointer_closure());
2452   ref_processor()->weak_oops_do(adjust_pointer_closure());
2453   // Roots were visited so references into the young gen in roots
2454   // may have been scanned.  Process them also.
2455   // Should the reference processor have a span that excludes
2456   // young gen objects?
2457   PSScavenge::reference_processor()->weak_oops_do(adjust_pointer_closure());
2458 }
2459 
2460 void PSParallelCompact::enqueue_region_draining_tasks(GCTaskQueue* q,
2461                                                       uint parallel_gc_threads)
2462 {
2463   TraceTime tm("drain task setup", print_phases(), true, gclog_or_tty);
2464 
2465   // Find the threads that are active
2466   unsigned int which = 0;
2467 
2468   const uint task_count = MAX2(parallel_gc_threads, 1U);
2469   for (uint j = 0; j < task_count; j++) {
2470     q->enqueue(new DrainStacksCompactionTask(j));
2471     ParCompactionManager::verify_region_list_empty(j);
2472     // Set the region stacks variables to "no" region stack values
2473     // so that they will be recognized and needing a region stack
2474     // in the stealing tasks if they do not get one by executing
2475     // a draining stack.
2476     ParCompactionManager* cm = ParCompactionManager::manager_array(j);
2477     cm->set_region_stack(NULL);
2478     cm->set_region_stack_index((uint)max_uintx);
2479   }
2480   ParCompactionManager::reset_recycled_stack_index();
2481 
2482   // Find all regions that are available (can be filled immediately) and
2483   // distribute them to the thread stacks.  The iteration is done in reverse
2484   // order (high to low) so the regions will be removed in ascending order.
2485 
2486   const ParallelCompactData& sd = PSParallelCompact::summary_data();
2487 
2488   size_t fillable_regions = 0;   // A count for diagnostic purposes.
2489   // A region index which corresponds to the tasks created above.
2490   // "which" must be 0 <= which < task_count
2491 
2492   which = 0;
2493   // id + 1 is used to test termination so unsigned  can
2494   // be used with an old_space_id == 0.
2495   for (unsigned int id = to_space_id; id + 1 > old_space_id; --id) {
2496     SpaceInfo* const space_info = _space_info + id;
2497     MutableSpace* const space = space_info->space();
2498     HeapWord* const new_top = space_info->new_top();
2499 
2500     const size_t beg_region = sd.addr_to_region_idx(space_info->dense_prefix());
2501     const size_t end_region =
2502       sd.addr_to_region_idx(sd.region_align_up(new_top));
2503 
2504     for (size_t cur = end_region - 1; cur + 1 > beg_region; --cur) {
2505       if (sd.region(cur)->claim_unsafe()) {
2506         ParCompactionManager::region_list_push(which, cur);
2507 
2508         if (TraceParallelOldGCCompactionPhase && Verbose) {
2509           const size_t count_mod_8 = fillable_regions & 7;
2510           if (count_mod_8 == 0) gclog_or_tty->print("fillable: ");
2511           gclog_or_tty->print(" " SIZE_FORMAT_W(7), cur);
2512           if (count_mod_8 == 7) gclog_or_tty->cr();
2513         }
2514 
2515         NOT_PRODUCT(++fillable_regions;)
2516 
2517         // Assign regions to tasks in round-robin fashion.
2518         if (++which == task_count) {
2519           assert(which <= parallel_gc_threads,
2520             "Inconsistent number of workers");
2521           which = 0;
2522         }
2523       }
2524     }
2525   }
2526 
2527   if (TraceParallelOldGCCompactionPhase) {
2528     if (Verbose && (fillable_regions & 7) != 0) gclog_or_tty->cr();
2529     gclog_or_tty->print_cr("%u initially fillable regions", fillable_regions);
2530   }
2531 }
2532 
2533 #define PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING 4
2534 
2535 void PSParallelCompact::enqueue_dense_prefix_tasks(GCTaskQueue* q,
2536                                                     uint parallel_gc_threads) {
2537   TraceTime tm("dense prefix task setup", print_phases(), true, gclog_or_tty);
2538 
2539   ParallelCompactData& sd = PSParallelCompact::summary_data();
2540 
2541   // Iterate over all the spaces adding tasks for updating
2542   // regions in the dense prefix.  Assume that 1 gc thread
2543   // will work on opening the gaps and the remaining gc threads
2544   // will work on the dense prefix.
2545   unsigned int space_id;
2546   for (space_id = old_space_id; space_id < last_space_id; ++ space_id) {
2547     HeapWord* const dense_prefix_end = _space_info[space_id].dense_prefix();
2548     const MutableSpace* const space = _space_info[space_id].space();
2549 
2550     if (dense_prefix_end == space->bottom()) {
2551       // There is no dense prefix for this space.
2552       continue;
2553     }
2554 
2555     // The dense prefix is before this region.
2556     size_t region_index_end_dense_prefix =
2557         sd.addr_to_region_idx(dense_prefix_end);
2558     RegionData* const dense_prefix_cp =
2559       sd.region(region_index_end_dense_prefix);
2560     assert(dense_prefix_end == space->end() ||
2561            dense_prefix_cp->available() ||
2562            dense_prefix_cp->claimed(),
2563            "The region after the dense prefix should always be ready to fill");
2564 
2565     size_t region_index_start = sd.addr_to_region_idx(space->bottom());
2566 
2567     // Is there dense prefix work?
2568     size_t total_dense_prefix_regions =
2569       region_index_end_dense_prefix - region_index_start;
2570     // How many regions of the dense prefix should be given to
2571     // each thread?
2572     if (total_dense_prefix_regions > 0) {
2573       uint tasks_for_dense_prefix = 1;
2574       if (total_dense_prefix_regions <=
2575           (parallel_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING)) {
2576         // Don't over partition.  This assumes that
2577         // PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING is a small integer value
2578         // so there are not many regions to process.
2579         tasks_for_dense_prefix = parallel_gc_threads;
2580       } else {
2581         // Over partition
2582         tasks_for_dense_prefix = parallel_gc_threads *
2583           PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING;
2584       }
2585       size_t regions_per_thread = total_dense_prefix_regions /
2586         tasks_for_dense_prefix;
2587       // Give each thread at least 1 region.
2588       if (regions_per_thread == 0) {
2589         regions_per_thread = 1;
2590       }
2591 
2592       for (uint k = 0; k < tasks_for_dense_prefix; k++) {
2593         if (region_index_start >= region_index_end_dense_prefix) {
2594           break;
2595         }
2596         // region_index_end is not processed
2597         size_t region_index_end = MIN2(region_index_start + regions_per_thread,
2598                                        region_index_end_dense_prefix);
2599         q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id),
2600                                              region_index_start,
2601                                              region_index_end));
2602         region_index_start = region_index_end;
2603       }
2604     }
2605     // This gets any part of the dense prefix that did not
2606     // fit evenly.
2607     if (region_index_start < region_index_end_dense_prefix) {
2608       q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id),
2609                                            region_index_start,
2610                                            region_index_end_dense_prefix));
2611     }
2612   }
2613 }
2614 
2615 void PSParallelCompact::enqueue_region_stealing_tasks(
2616                                      GCTaskQueue* q,
2617                                      ParallelTaskTerminator* terminator_ptr,
2618                                      uint parallel_gc_threads) {
2619   TraceTime tm("steal task setup", print_phases(), true, gclog_or_tty);
2620 
2621   // Once a thread has drained it's stack, it should try to steal regions from
2622   // other threads.
2623   if (parallel_gc_threads > 1) {
2624     for (uint j = 0; j < parallel_gc_threads; j++) {
2625       q->enqueue(new StealRegionCompactionTask(terminator_ptr));
2626     }
2627   }
2628 }
2629 
2630 void PSParallelCompact::compact() {
2631   // trace("5");
2632   TraceTime tm("compaction phase", print_phases(), true, gclog_or_tty);
2633 
2634   ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
2635   assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
2636   PSOldGen* old_gen = heap->old_gen();
2637   old_gen->start_array()->reset();
2638   uint parallel_gc_threads = heap->gc_task_manager()->workers();
2639   uint active_gc_threads = heap->gc_task_manager()->active_workers();
2640   TaskQueueSetSuper* qset = ParCompactionManager::region_array();
2641   ParallelTaskTerminator terminator(active_gc_threads, qset);
2642 
2643   GCTaskQueue* q = GCTaskQueue::create();
2644   enqueue_region_draining_tasks(q, active_gc_threads);
2645   enqueue_dense_prefix_tasks(q, active_gc_threads);
2646   enqueue_region_stealing_tasks(q, &terminator, active_gc_threads);
2647 
2648   {
2649     TraceTime tm_pc("par compact", print_phases(), true, gclog_or_tty);
2650 
2651     gc_task_manager()->execute_and_wait(q);
2652 
2653 #ifdef  ASSERT
2654     // Verify that all regions have been processed before the deferred updates.
2655     for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2656       verify_complete(SpaceId(id));
2657     }
2658 #endif
2659   }
2660 
2661   {
2662     // Update the deferred objects, if any.  Any compaction manager can be used.
2663     TraceTime tm_du("deferred updates", print_phases(), true, gclog_or_tty);
2664     ParCompactionManager* cm = ParCompactionManager::manager_array(0);
2665     for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2666       update_deferred_objects(cm, SpaceId(id));
2667     }
2668   }
2669 }
2670 
2671 #ifdef  ASSERT
2672 void PSParallelCompact::verify_complete(SpaceId space_id) {
2673   // All Regions between space bottom() to new_top() should be marked as filled
2674   // and all Regions between new_top() and top() should be available (i.e.,
2675   // should have been emptied).
2676   ParallelCompactData& sd = summary_data();
2677   SpaceInfo si = _space_info[space_id];
2678   HeapWord* new_top_addr = sd.region_align_up(si.new_top());
2679   HeapWord* old_top_addr = sd.region_align_up(si.space()->top());
2680   const size_t beg_region = sd.addr_to_region_idx(si.space()->bottom());
2681   const size_t new_top_region = sd.addr_to_region_idx(new_top_addr);
2682   const size_t old_top_region = sd.addr_to_region_idx(old_top_addr);
2683 
2684   bool issued_a_warning = false;
2685 
2686   size_t cur_region;
2687   for (cur_region = beg_region; cur_region < new_top_region; ++cur_region) {
2688     const RegionData* const c = sd.region(cur_region);
2689     if (!c->completed()) {
2690       warning("region " SIZE_FORMAT " not filled:  "
2691               "destination_count=" SIZE_FORMAT,
2692               cur_region, c->destination_count());
2693       issued_a_warning = true;
2694     }
2695   }
2696 
2697   for (cur_region = new_top_region; cur_region < old_top_region; ++cur_region) {
2698     const RegionData* const c = sd.region(cur_region);
2699     if (!c->available()) {
2700       warning("region " SIZE_FORMAT " not empty:   "
2701               "destination_count=" SIZE_FORMAT,
2702               cur_region, c->destination_count());
2703       issued_a_warning = true;
2704     }
2705   }
2706 
2707   if (issued_a_warning) {
2708     print_region_ranges();
2709   }
2710 }
2711 #endif  // #ifdef ASSERT
2712 
2713 // Update interior oops in the ranges of regions [beg_region, end_region).
2714 void
2715 PSParallelCompact::update_and_deadwood_in_dense_prefix(ParCompactionManager* cm,
2716                                                        SpaceId space_id,
2717                                                        size_t beg_region,
2718                                                        size_t end_region) {
2719   ParallelCompactData& sd = summary_data();
2720   ParMarkBitMap* const mbm = mark_bitmap();
2721 
2722   HeapWord* beg_addr = sd.region_to_addr(beg_region);
2723   HeapWord* const end_addr = sd.region_to_addr(end_region);
2724   assert(beg_region <= end_region, "bad region range");
2725   assert(end_addr <= dense_prefix(space_id), "not in the dense prefix");
2726 
2727 #ifdef  ASSERT
2728   // Claim the regions to avoid triggering an assert when they are marked as
2729   // filled.
2730   for (size_t claim_region = beg_region; claim_region < end_region; ++claim_region) {
2731     assert(sd.region(claim_region)->claim_unsafe(), "claim() failed");
2732   }
2733 #endif  // #ifdef ASSERT
2734 
2735   if (beg_addr != space(space_id)->bottom()) {
2736     // Find the first live object or block of dead space that *starts* in this
2737     // range of regions.  If a partial object crosses onto the region, skip it;
2738     // it will be marked for 'deferred update' when the object head is
2739     // processed.  If dead space crosses onto the region, it is also skipped; it
2740     // will be filled when the prior region is processed.  If neither of those
2741     // apply, the first word in the region is the start of a live object or dead
2742     // space.
2743     assert(beg_addr > space(space_id)->bottom(), "sanity");
2744     const RegionData* const cp = sd.region(beg_region);
2745     if (cp->partial_obj_size() != 0) {
2746       beg_addr = sd.partial_obj_end(beg_region);
2747     } else if (dead_space_crosses_boundary(cp, mbm->addr_to_bit(beg_addr))) {
2748       beg_addr = mbm->find_obj_beg(beg_addr, end_addr);
2749     }
2750   }
2751 
2752   if (beg_addr < end_addr) {
2753     // A live object or block of dead space starts in this range of Regions.
2754      HeapWord* const dense_prefix_end = dense_prefix(space_id);
2755 
2756     // Create closures and iterate.
2757     UpdateOnlyClosure update_closure(mbm, cm, space_id);
2758     FillClosure fill_closure(cm, space_id);
2759     ParMarkBitMap::IterationStatus status;
2760     status = mbm->iterate(&update_closure, &fill_closure, beg_addr, end_addr,
2761                           dense_prefix_end);
2762     if (status == ParMarkBitMap::incomplete) {
2763       update_closure.do_addr(update_closure.source());
2764     }
2765   }
2766 
2767   // Mark the regions as filled.
2768   RegionData* const beg_cp = sd.region(beg_region);
2769   RegionData* const end_cp = sd.region(end_region);
2770   for (RegionData* cp = beg_cp; cp < end_cp; ++cp) {
2771     cp->set_completed();
2772   }
2773 }
2774 
2775 // Return the SpaceId for the space containing addr.  If addr is not in the
2776 // heap, last_space_id is returned.  In debug mode it expects the address to be
2777 // in the heap and asserts such.
2778 PSParallelCompact::SpaceId PSParallelCompact::space_id(HeapWord* addr) {
2779   assert(Universe::heap()->is_in_reserved(addr), "addr not in the heap");
2780 
2781   for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2782     if (_space_info[id].space()->contains(addr)) {
2783       return SpaceId(id);
2784     }
2785   }
2786 
2787   assert(false, "no space contains the addr");
2788   return last_space_id;
2789 }
2790 
2791 void PSParallelCompact::update_deferred_objects(ParCompactionManager* cm,
2792                                                 SpaceId id) {
2793   assert(id < last_space_id, "bad space id");
2794 
2795   ParallelCompactData& sd = summary_data();
2796   const SpaceInfo* const space_info = _space_info + id;
2797   ObjectStartArray* const start_array = space_info->start_array();
2798 
2799   const MutableSpace* const space = space_info->space();
2800   assert(space_info->dense_prefix() >= space->bottom(), "dense_prefix not set");
2801   HeapWord* const beg_addr = space_info->dense_prefix();
2802   HeapWord* const end_addr = sd.region_align_up(space_info->new_top());
2803 
2804   const RegionData* const beg_region = sd.addr_to_region_ptr(beg_addr);
2805   const RegionData* const end_region = sd.addr_to_region_ptr(end_addr);
2806   const RegionData* cur_region;
2807   for (cur_region = beg_region; cur_region < end_region; ++cur_region) {
2808     HeapWord* const addr = cur_region->deferred_obj_addr();
2809     if (addr != NULL) {
2810       if (start_array != NULL) {
2811         start_array->allocate_block(addr);
2812       }
2813       oop(addr)->update_contents(cm);
2814       assert(oop(addr)->is_oop_or_null(), "should be an oop now");
2815     }
2816   }
2817 }
2818 
2819 // Skip over count live words starting from beg, and return the address of the
2820 // next live word.  Unless marked, the word corresponding to beg is assumed to
2821 // be dead.  Callers must either ensure beg does not correspond to the middle of
2822 // an object, or account for those live words in some other way.  Callers must
2823 // also ensure that there are enough live words in the range [beg, end) to skip.
2824 HeapWord*
2825 PSParallelCompact::skip_live_words(HeapWord* beg, HeapWord* end, size_t count)
2826 {
2827   assert(count > 0, "sanity");
2828 
2829   ParMarkBitMap* m = mark_bitmap();
2830   idx_t bits_to_skip = m->words_to_bits(count);
2831   idx_t cur_beg = m->addr_to_bit(beg);
2832   const idx_t search_end = BitMap::word_align_up(m->addr_to_bit(end));
2833 
2834   do {
2835     cur_beg = m->find_obj_beg(cur_beg, search_end);
2836     idx_t cur_end = m->find_obj_end(cur_beg, search_end);
2837     const size_t obj_bits = cur_end - cur_beg + 1;
2838     if (obj_bits > bits_to_skip) {
2839       return m->bit_to_addr(cur_beg + bits_to_skip);
2840     }
2841     bits_to_skip -= obj_bits;
2842     cur_beg = cur_end + 1;
2843   } while (bits_to_skip > 0);
2844 
2845   // Skipping the desired number of words landed just past the end of an object.
2846   // Find the start of the next object.
2847   cur_beg = m->find_obj_beg(cur_beg, search_end);
2848   assert(cur_beg < m->addr_to_bit(end), "not enough live words to skip");
2849   return m->bit_to_addr(cur_beg);
2850 }
2851 
2852 HeapWord* PSParallelCompact::first_src_addr(HeapWord* const dest_addr,
2853                                             SpaceId src_space_id,
2854                                             size_t src_region_idx)
2855 {
2856   assert(summary_data().is_region_aligned(dest_addr), "not aligned");
2857 
2858   const SplitInfo& split_info = _space_info[src_space_id].split_info();
2859   if (split_info.dest_region_addr() == dest_addr) {
2860     // The partial object ending at the split point contains the first word to
2861     // be copied to dest_addr.
2862     return split_info.first_src_addr();
2863   }
2864 
2865   const ParallelCompactData& sd = summary_data();
2866   ParMarkBitMap* const bitmap = mark_bitmap();
2867   const size_t RegionSize = ParallelCompactData::RegionSize;
2868 
2869   assert(sd.is_region_aligned(dest_addr), "not aligned");
2870   const RegionData* const src_region_ptr = sd.region(src_region_idx);
2871   const size_t partial_obj_size = src_region_ptr->partial_obj_size();
2872   HeapWord* const src_region_destination = src_region_ptr->destination();
2873 
2874   assert(dest_addr >= src_region_destination, "wrong src region");
2875   assert(src_region_ptr->data_size() > 0, "src region cannot be empty");
2876 
2877   HeapWord* const src_region_beg = sd.region_to_addr(src_region_idx);
2878   HeapWord* const src_region_end = src_region_beg + RegionSize;
2879 
2880   HeapWord* addr = src_region_beg;
2881   if (dest_addr == src_region_destination) {
2882     // Return the first live word in the source region.
2883     if (partial_obj_size == 0) {
2884       addr = bitmap->find_obj_beg(addr, src_region_end);
2885       assert(addr < src_region_end, "no objects start in src region");
2886     }
2887     return addr;
2888   }
2889 
2890   // Must skip some live data.
2891   size_t words_to_skip = dest_addr - src_region_destination;
2892   assert(src_region_ptr->data_size() > words_to_skip, "wrong src region");
2893 
2894   if (partial_obj_size >= words_to_skip) {
2895     // All the live words to skip are part of the partial object.
2896     addr += words_to_skip;
2897     if (partial_obj_size == words_to_skip) {
2898       // Find the first live word past the partial object.
2899       addr = bitmap->find_obj_beg(addr, src_region_end);
2900       assert(addr < src_region_end, "wrong src region");
2901     }
2902     return addr;
2903   }
2904 
2905   // Skip over the partial object (if any).
2906   if (partial_obj_size != 0) {
2907     words_to_skip -= partial_obj_size;
2908     addr += partial_obj_size;
2909   }
2910 
2911   // Skip over live words due to objects that start in the region.
2912   addr = skip_live_words(addr, src_region_end, words_to_skip);
2913   assert(addr < src_region_end, "wrong src region");
2914   return addr;
2915 }
2916 
2917 void PSParallelCompact::decrement_destination_counts(ParCompactionManager* cm,
2918                                                      SpaceId src_space_id,
2919                                                      size_t beg_region,
2920                                                      HeapWord* end_addr)
2921 {
2922   ParallelCompactData& sd = summary_data();
2923 
2924 #ifdef ASSERT
2925   MutableSpace* const src_space = _space_info[src_space_id].space();
2926   HeapWord* const beg_addr = sd.region_to_addr(beg_region);
2927   assert(src_space->contains(beg_addr) || beg_addr == src_space->end(),
2928          "src_space_id does not match beg_addr");
2929   assert(src_space->contains(end_addr) || end_addr == src_space->end(),
2930          "src_space_id does not match end_addr");
2931 #endif // #ifdef ASSERT
2932 
2933   RegionData* const beg = sd.region(beg_region);
2934   RegionData* const end = sd.addr_to_region_ptr(sd.region_align_up(end_addr));
2935 
2936   // Regions up to new_top() are enqueued if they become available.
2937   HeapWord* const new_top = _space_info[src_space_id].new_top();
2938   RegionData* const enqueue_end =
2939     sd.addr_to_region_ptr(sd.region_align_up(new_top));
2940 
2941   for (RegionData* cur = beg; cur < end; ++cur) {
2942     assert(cur->data_size() > 0, "region must have live data");
2943     cur->decrement_destination_count();
2944     if (cur < enqueue_end && cur->available() && cur->claim()) {
2945       cm->push_region(sd.region(cur));
2946     }
2947   }
2948 }
2949 
2950 size_t PSParallelCompact::next_src_region(MoveAndUpdateClosure& closure,
2951                                           SpaceId& src_space_id,
2952                                           HeapWord*& src_space_top,
2953                                           HeapWord* end_addr)
2954 {
2955   typedef ParallelCompactData::RegionData RegionData;
2956 
2957   ParallelCompactData& sd = PSParallelCompact::summary_data();
2958   const size_t region_size = ParallelCompactData::RegionSize;
2959 
2960   size_t src_region_idx = 0;
2961 
2962   // Skip empty regions (if any) up to the top of the space.
2963   HeapWord* const src_aligned_up = sd.region_align_up(end_addr);
2964   RegionData* src_region_ptr = sd.addr_to_region_ptr(src_aligned_up);
2965   HeapWord* const top_aligned_up = sd.region_align_up(src_space_top);
2966   const RegionData* const top_region_ptr =
2967     sd.addr_to_region_ptr(top_aligned_up);
2968   while (src_region_ptr < top_region_ptr && src_region_ptr->data_size() == 0) {
2969     ++src_region_ptr;
2970   }
2971 
2972   if (src_region_ptr < top_region_ptr) {
2973     // The next source region is in the current space.  Update src_region_idx
2974     // and the source address to match src_region_ptr.
2975     src_region_idx = sd.region(src_region_ptr);
2976     HeapWord* const src_region_addr = sd.region_to_addr(src_region_idx);
2977     if (src_region_addr > closure.source()) {
2978       closure.set_source(src_region_addr);
2979     }
2980     return src_region_idx;
2981   }
2982 
2983   // Switch to a new source space and find the first non-empty region.
2984   unsigned int space_id = src_space_id + 1;
2985   assert(space_id < last_space_id, "not enough spaces");
2986 
2987   HeapWord* const destination = closure.destination();
2988 
2989   do {
2990     MutableSpace* space = _space_info[space_id].space();
2991     HeapWord* const bottom = space->bottom();
2992     const RegionData* const bottom_cp = sd.addr_to_region_ptr(bottom);
2993 
2994     // Iterate over the spaces that do not compact into themselves.
2995     if (bottom_cp->destination() != bottom) {
2996       HeapWord* const top_aligned_up = sd.region_align_up(space->top());
2997       const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
2998 
2999       for (const RegionData* src_cp = bottom_cp; src_cp < top_cp; ++src_cp) {
3000         if (src_cp->live_obj_size() > 0) {
3001           // Found it.
3002           assert(src_cp->destination() == destination,
3003                  "first live obj in the space must match the destination");
3004           assert(src_cp->partial_obj_size() == 0,
3005                  "a space cannot begin with a partial obj");
3006 
3007           src_space_id = SpaceId(space_id);
3008           src_space_top = space->top();
3009           const size_t src_region_idx = sd.region(src_cp);
3010           closure.set_source(sd.region_to_addr(src_region_idx));
3011           return src_region_idx;
3012         } else {
3013           assert(src_cp->data_size() == 0, "sanity");
3014         }
3015       }
3016     }
3017   } while (++space_id < last_space_id);
3018 
3019   assert(false, "no source region was found");
3020   return 0;
3021 }
3022 
3023 void PSParallelCompact::fill_region(ParCompactionManager* cm, size_t region_idx)
3024 {
3025   typedef ParMarkBitMap::IterationStatus IterationStatus;
3026   const size_t RegionSize = ParallelCompactData::RegionSize;
3027   ParMarkBitMap* const bitmap = mark_bitmap();
3028   ParallelCompactData& sd = summary_data();
3029   RegionData* const region_ptr = sd.region(region_idx);
3030 
3031   // Get the items needed to construct the closure.
3032   HeapWord* dest_addr = sd.region_to_addr(region_idx);
3033   SpaceId dest_space_id = space_id(dest_addr);
3034   ObjectStartArray* start_array = _space_info[dest_space_id].start_array();
3035   HeapWord* new_top = _space_info[dest_space_id].new_top();
3036   assert(dest_addr < new_top, "sanity");
3037   const size_t words = MIN2(pointer_delta(new_top, dest_addr), RegionSize);
3038 
3039   // Get the source region and related info.
3040   size_t src_region_idx = region_ptr->source_region();
3041   SpaceId src_space_id = space_id(sd.region_to_addr(src_region_idx));
3042   HeapWord* src_space_top = _space_info[src_space_id].space()->top();
3043 
3044   MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words);
3045   closure.set_source(first_src_addr(dest_addr, src_space_id, src_region_idx));
3046 
3047   // Adjust src_region_idx to prepare for decrementing destination counts (the
3048   // destination count is not decremented when a region is copied to itself).
3049   if (src_region_idx == region_idx) {
3050     src_region_idx += 1;
3051   }
3052 
3053   if (bitmap->is_unmarked(closure.source())) {
3054     // The first source word is in the middle of an object; copy the remainder
3055     // of the object or as much as will fit.  The fact that pointer updates were
3056     // deferred will be noted when the object header is processed.
3057     HeapWord* const old_src_addr = closure.source();
3058     closure.copy_partial_obj();
3059     if (closure.is_full()) {
3060       decrement_destination_counts(cm, src_space_id, src_region_idx,
3061                                    closure.source());
3062       region_ptr->set_deferred_obj_addr(NULL);
3063       region_ptr->set_completed();
3064       return;
3065     }
3066 
3067     HeapWord* const end_addr = sd.region_align_down(closure.source());
3068     if (sd.region_align_down(old_src_addr) != end_addr) {
3069       // The partial object was copied from more than one source region.
3070       decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
3071 
3072       // Move to the next source region, possibly switching spaces as well.  All
3073       // args except end_addr may be modified.
3074       src_region_idx = next_src_region(closure, src_space_id, src_space_top,
3075                                        end_addr);
3076     }
3077   }
3078 
3079   do {
3080     HeapWord* const cur_addr = closure.source();
3081     HeapWord* const end_addr = MIN2(sd.region_align_up(cur_addr + 1),
3082                                     src_space_top);
3083     IterationStatus status = bitmap->iterate(&closure, cur_addr, end_addr);
3084 
3085     if (status == ParMarkBitMap::incomplete) {
3086       // The last obj that starts in the source region does not end in the
3087       // region.
3088       assert(closure.source() < end_addr, "sanity");
3089       HeapWord* const obj_beg = closure.source();
3090       HeapWord* const range_end = MIN2(obj_beg + closure.words_remaining(),
3091                                        src_space_top);
3092       HeapWord* const obj_end = bitmap->find_obj_end(obj_beg, range_end);
3093       if (obj_end < range_end) {
3094         // The end was found; the entire object will fit.
3095         status = closure.do_addr(obj_beg, bitmap->obj_size(obj_beg, obj_end));
3096         assert(status != ParMarkBitMap::would_overflow, "sanity");
3097       } else {
3098         // The end was not found; the object will not fit.
3099         assert(range_end < src_space_top, "obj cannot cross space boundary");
3100         status = ParMarkBitMap::would_overflow;
3101       }
3102     }
3103 
3104     if (status == ParMarkBitMap::would_overflow) {
3105       // The last object did not fit.  Note that interior oop updates were
3106       // deferred, then copy enough of the object to fill the region.
3107       region_ptr->set_deferred_obj_addr(closure.destination());
3108       status = closure.copy_until_full(); // copies from closure.source()
3109 
3110       decrement_destination_counts(cm, src_space_id, src_region_idx,
3111                                    closure.source());
3112       region_ptr->set_completed();
3113       return;
3114     }
3115 
3116     if (status == ParMarkBitMap::full) {
3117       decrement_destination_counts(cm, src_space_id, src_region_idx,
3118                                    closure.source());
3119       region_ptr->set_deferred_obj_addr(NULL);
3120       region_ptr->set_completed();
3121       return;
3122     }
3123 
3124     decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
3125 
3126     // Move to the next source region, possibly switching spaces as well.  All
3127     // args except end_addr may be modified.
3128     src_region_idx = next_src_region(closure, src_space_id, src_space_top,
3129                                      end_addr);
3130   } while (true);
3131 }
3132 
3133 void
3134 PSParallelCompact::move_and_update(ParCompactionManager* cm, SpaceId space_id) {
3135   const MutableSpace* sp = space(space_id);
3136   if (sp->is_empty()) {
3137     return;
3138   }
3139 
3140   ParallelCompactData& sd = PSParallelCompact::summary_data();
3141   ParMarkBitMap* const bitmap = mark_bitmap();
3142   HeapWord* const dp_addr = dense_prefix(space_id);
3143   HeapWord* beg_addr = sp->bottom();
3144   HeapWord* end_addr = sp->top();
3145 
3146   assert(beg_addr <= dp_addr && dp_addr <= end_addr, "bad dense prefix");
3147 
3148   const size_t beg_region = sd.addr_to_region_idx(beg_addr);
3149   const size_t dp_region = sd.addr_to_region_idx(dp_addr);
3150   if (beg_region < dp_region) {
3151     update_and_deadwood_in_dense_prefix(cm, space_id, beg_region, dp_region);
3152   }
3153 
3154   // The destination of the first live object that starts in the region is one
3155   // past the end of the partial object entering the region (if any).
3156   HeapWord* const dest_addr = sd.partial_obj_end(dp_region);
3157   HeapWord* const new_top = _space_info[space_id].new_top();
3158   assert(new_top >= dest_addr, "bad new_top value");
3159   const size_t words = pointer_delta(new_top, dest_addr);
3160 
3161   if (words > 0) {
3162     ObjectStartArray* start_array = _space_info[space_id].start_array();
3163     MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words);
3164 
3165     ParMarkBitMap::IterationStatus status;
3166     status = bitmap->iterate(&closure, dest_addr, end_addr);
3167     assert(status == ParMarkBitMap::full, "iteration not complete");
3168     assert(bitmap->find_obj_beg(closure.source(), end_addr) == end_addr,
3169            "live objects skipped because closure is full");
3170   }
3171 }
3172 
3173 jlong PSParallelCompact::millis_since_last_gc() {
3174   // We need a monotonically non-deccreasing time in ms but
3175   // os::javaTimeMillis() does not guarantee monotonicity.
3176   jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
3177   jlong ret_val = now - _time_of_last_gc;
3178   // XXX See note in genCollectedHeap::millis_since_last_gc().
3179   if (ret_val < 0) {
3180     NOT_PRODUCT(warning("time warp: "INT64_FORMAT, ret_val);)
3181     return 0;
3182   }
3183   return ret_val;
3184 }
3185 
3186 void PSParallelCompact::reset_millis_since_last_gc() {
3187   // We need a monotonically non-deccreasing time in ms but
3188   // os::javaTimeMillis() does not guarantee monotonicity.
3189   _time_of_last_gc = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
3190 }
3191 
3192 ParMarkBitMap::IterationStatus MoveAndUpdateClosure::copy_until_full()
3193 {
3194   if (source() != destination()) {
3195     DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3196     Copy::aligned_conjoint_words(source(), destination(), words_remaining());
3197   }
3198   update_state(words_remaining());
3199   assert(is_full(), "sanity");
3200   return ParMarkBitMap::full;
3201 }
3202 
3203 void MoveAndUpdateClosure::copy_partial_obj()
3204 {
3205   size_t words = words_remaining();
3206 
3207   HeapWord* const range_end = MIN2(source() + words, bitmap()->region_end());
3208   HeapWord* const end_addr = bitmap()->find_obj_end(source(), range_end);
3209   if (end_addr < range_end) {
3210     words = bitmap()->obj_size(source(), end_addr);
3211   }
3212 
3213   // This test is necessary; if omitted, the pointer updates to a partial object
3214   // that crosses the dense prefix boundary could be overwritten.
3215   if (source() != destination()) {
3216     DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3217     Copy::aligned_conjoint_words(source(), destination(), words);
3218   }
3219   update_state(words);
3220 }
3221 
3222 ParMarkBitMapClosure::IterationStatus
3223 MoveAndUpdateClosure::do_addr(HeapWord* addr, size_t words) {
3224   assert(destination() != NULL, "sanity");
3225   assert(bitmap()->obj_size(addr) == words, "bad size");
3226 
3227   _source = addr;
3228   assert(PSParallelCompact::summary_data().calc_new_pointer(source()) ==
3229          destination(), "wrong destination");
3230 
3231   if (words > words_remaining()) {
3232     return ParMarkBitMap::would_overflow;
3233   }
3234 
3235   // The start_array must be updated even if the object is not moving.
3236   if (_start_array != NULL) {
3237     _start_array->allocate_block(destination());
3238   }
3239 
3240   if (destination() != source()) {
3241     DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3242     Copy::aligned_conjoint_words(source(), destination(), words);
3243   }
3244 
3245   oop moved_oop = (oop) destination();
3246   moved_oop->update_contents(compaction_manager());
3247   assert(moved_oop->is_oop_or_null(), "Object should be whole at this point");
3248 
3249   update_state(words);
3250   assert(destination() == (HeapWord*)moved_oop + moved_oop->size(), "sanity");
3251   return is_full() ? ParMarkBitMap::full : ParMarkBitMap::incomplete;
3252 }
3253 
3254 UpdateOnlyClosure::UpdateOnlyClosure(ParMarkBitMap* mbm,
3255                                      ParCompactionManager* cm,
3256                                      PSParallelCompact::SpaceId space_id) :
3257   ParMarkBitMapClosure(mbm, cm),
3258   _space_id(space_id),
3259   _start_array(PSParallelCompact::start_array(space_id))
3260 {
3261 }
3262 
3263 // Updates the references in the object to their new values.
3264 ParMarkBitMapClosure::IterationStatus
3265 UpdateOnlyClosure::do_addr(HeapWord* addr, size_t words) {
3266   do_addr(addr);
3267   return ParMarkBitMap::incomplete;
3268 }