1 /*
   2  * Copyright (c) 2005, 2016, 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/stringTable.hpp"
  27 #include "classfile/symbolTable.hpp"
  28 #include "classfile/systemDictionary.hpp"
  29 #include "code/codeCache.hpp"
  30 #include "gc/parallel/gcTaskManager.hpp"
  31 #include "gc/parallel/parallelScavengeHeap.inline.hpp"
  32 #include "gc/parallel/pcTasks.hpp"
  33 #include "gc/parallel/psAdaptiveSizePolicy.hpp"
  34 #include "gc/parallel/psCompactionManager.inline.hpp"
  35 #include "gc/parallel/psMarkSweep.hpp"
  36 #include "gc/parallel/psMarkSweepDecorator.hpp"
  37 #include "gc/parallel/psOldGen.hpp"
  38 #include "gc/parallel/psParallelCompact.inline.hpp"
  39 #include "gc/parallel/psPromotionManager.inline.hpp"
  40 #include "gc/parallel/psScavenge.hpp"
  41 #include "gc/parallel/psYoungGen.hpp"
  42 #include "gc/shared/gcCause.hpp"
  43 #include "gc/shared/gcHeapSummary.hpp"
  44 #include "gc/shared/gcId.hpp"
  45 #include "gc/shared/gcLocker.inline.hpp"
  46 #include "gc/shared/gcTimer.hpp"
  47 #include "gc/shared/gcTrace.hpp"
  48 #include "gc/shared/gcTraceTime.inline.hpp"
  49 #include "gc/shared/isGCActiveMark.hpp"
  50 #include "gc/shared/referencePolicy.hpp"
  51 #include "gc/shared/referenceProcessor.hpp"
  52 #include "gc/shared/spaceDecorator.hpp"
  53 #include "logging/log.hpp"
  54 #include "memory/resourceArea.hpp"
  55 #include "oops/instanceKlass.inline.hpp"
  56 #include "oops/instanceMirrorKlass.inline.hpp"
  57 #include "oops/methodData.hpp"
  58 #include "oops/objArrayKlass.inline.hpp"
  59 #include "oops/oop.inline.hpp"
  60 #include "runtime/atomic.hpp"
  61 #include "runtime/fprofiler.hpp"
  62 #include "runtime/safepoint.hpp"
  63 #include "runtime/vmThread.hpp"
  64 #include "services/management.hpp"
  65 #include "services/memTracker.hpp"
  66 #include "services/memoryService.hpp"
  67 #include "utilities/events.hpp"
  68 #include "utilities/stack.inline.hpp"
  69 
  70 #include <math.h>
  71 
  72 // All sizes are in HeapWords.
  73 const size_t ParallelCompactData::Log2RegionSize  = 16; // 64K words
  74 const size_t ParallelCompactData::RegionSize      = (size_t)1 << Log2RegionSize;
  75 const size_t ParallelCompactData::RegionSizeBytes =
  76   RegionSize << LogHeapWordSize;
  77 const size_t ParallelCompactData::RegionSizeOffsetMask = RegionSize - 1;
  78 const size_t ParallelCompactData::RegionAddrOffsetMask = RegionSizeBytes - 1;
  79 const size_t ParallelCompactData::RegionAddrMask       = ~RegionAddrOffsetMask;
  80 
  81 const size_t ParallelCompactData::Log2BlockSize   = 7; // 128 words
  82 const size_t ParallelCompactData::BlockSize       = (size_t)1 << Log2BlockSize;
  83 const size_t ParallelCompactData::BlockSizeBytes  =
  84   BlockSize << LogHeapWordSize;
  85 const size_t ParallelCompactData::BlockSizeOffsetMask = BlockSize - 1;
  86 const size_t ParallelCompactData::BlockAddrOffsetMask = BlockSizeBytes - 1;
  87 const size_t ParallelCompactData::BlockAddrMask       = ~BlockAddrOffsetMask;
  88 
  89 const size_t ParallelCompactData::BlocksPerRegion = RegionSize / BlockSize;
  90 const size_t ParallelCompactData::Log2BlocksPerRegion =
  91   Log2RegionSize - Log2BlockSize;
  92 
  93 const ParallelCompactData::RegionData::region_sz_t
  94 ParallelCompactData::RegionData::dc_shift = 27;
  95 
  96 const ParallelCompactData::RegionData::region_sz_t
  97 ParallelCompactData::RegionData::dc_mask = ~0U << dc_shift;
  98 
  99 const ParallelCompactData::RegionData::region_sz_t
 100 ParallelCompactData::RegionData::dc_one = 0x1U << dc_shift;
 101 
 102 const ParallelCompactData::RegionData::region_sz_t
 103 ParallelCompactData::RegionData::los_mask = ~dc_mask;
 104 
 105 const ParallelCompactData::RegionData::region_sz_t
 106 ParallelCompactData::RegionData::dc_claimed = 0x8U << dc_shift;
 107 
 108 const ParallelCompactData::RegionData::region_sz_t
 109 ParallelCompactData::RegionData::dc_completed = 0xcU << dc_shift;
 110 
 111 SpaceInfo PSParallelCompact::_space_info[PSParallelCompact::last_space_id];
 112 
 113 ReferenceProcessor* PSParallelCompact::_ref_processor = NULL;
 114 
 115 double PSParallelCompact::_dwl_mean;
 116 double PSParallelCompact::_dwl_std_dev;
 117 double PSParallelCompact::_dwl_first_term;
 118 double PSParallelCompact::_dwl_adjustment;
 119 #ifdef  ASSERT
 120 bool   PSParallelCompact::_dwl_initialized = false;
 121 #endif  // #ifdef ASSERT
 122 
 123 void SplitInfo::record(size_t src_region_idx, size_t partial_obj_size,
 124                        HeapWord* destination)
 125 {
 126   assert(src_region_idx != 0, "invalid src_region_idx");
 127   assert(partial_obj_size != 0, "invalid partial_obj_size argument");
 128   assert(destination != NULL, "invalid destination argument");
 129 
 130   _src_region_idx = src_region_idx;
 131   _partial_obj_size = partial_obj_size;
 132   _destination = destination;
 133 
 134   // These fields may not be updated below, so make sure they're clear.
 135   assert(_dest_region_addr == NULL, "should have been cleared");
 136   assert(_first_src_addr == NULL, "should have been cleared");
 137 
 138   // Determine the number of destination regions for the partial object.
 139   HeapWord* const last_word = destination + partial_obj_size - 1;
 140   const ParallelCompactData& sd = PSParallelCompact::summary_data();
 141   HeapWord* const beg_region_addr = sd.region_align_down(destination);
 142   HeapWord* const end_region_addr = sd.region_align_down(last_word);
 143 
 144   if (beg_region_addr == end_region_addr) {
 145     // One destination region.
 146     _destination_count = 1;
 147     if (end_region_addr == destination) {
 148       // The destination falls on a region boundary, thus the first word of the
 149       // partial object will be the first word copied to the destination region.
 150       _dest_region_addr = end_region_addr;
 151       _first_src_addr = sd.region_to_addr(src_region_idx);
 152     }
 153   } else {
 154     // Two destination regions.  When copied, the partial object will cross a
 155     // destination region boundary, so a word somewhere within the partial
 156     // object will be the first word copied to the second destination region.
 157     _destination_count = 2;
 158     _dest_region_addr = end_region_addr;
 159     const size_t ofs = pointer_delta(end_region_addr, destination);
 160     assert(ofs < _partial_obj_size, "sanity");
 161     _first_src_addr = sd.region_to_addr(src_region_idx) + ofs;
 162   }
 163 }
 164 
 165 void SplitInfo::clear()
 166 {
 167   _src_region_idx = 0;
 168   _partial_obj_size = 0;
 169   _destination = NULL;
 170   _destination_count = 0;
 171   _dest_region_addr = NULL;
 172   _first_src_addr = NULL;
 173   assert(!is_valid(), "sanity");
 174 }
 175 
 176 #ifdef  ASSERT
 177 void SplitInfo::verify_clear()
 178 {
 179   assert(_src_region_idx == 0, "not clear");
 180   assert(_partial_obj_size == 0, "not clear");
 181   assert(_destination == NULL, "not clear");
 182   assert(_destination_count == 0, "not clear");
 183   assert(_dest_region_addr == NULL, "not clear");
 184   assert(_first_src_addr == NULL, "not clear");
 185 }
 186 #endif  // #ifdef ASSERT
 187 
 188 
 189 void PSParallelCompact::print_on_error(outputStream* st) {
 190   _mark_bitmap.print_on_error(st);
 191 }
 192 
 193 #ifndef PRODUCT
 194 const char* PSParallelCompact::space_names[] = {
 195   "old ", "eden", "from", "to  "
 196 };
 197 
 198 void PSParallelCompact::print_region_ranges() {
 199   if (!log_develop_is_enabled(Trace, gc, compaction)) {
 200     return;
 201   }
 202   Log(gc, compaction) log;
 203   ResourceMark rm;
 204   Universe::print_on(log.trace_stream());
 205   log.trace("space  bottom     top        end        new_top");
 206   log.trace("------ ---------- ---------- ---------- ----------");
 207 
 208   for (unsigned int id = 0; id < last_space_id; ++id) {
 209     const MutableSpace* space = _space_info[id].space();
 210     log.trace("%u %s "
 211               SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " "
 212               SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " ",
 213               id, space_names[id],
 214               summary_data().addr_to_region_idx(space->bottom()),
 215               summary_data().addr_to_region_idx(space->top()),
 216               summary_data().addr_to_region_idx(space->end()),
 217               summary_data().addr_to_region_idx(_space_info[id].new_top()));
 218   }
 219 }
 220 
 221 void
 222 print_generic_summary_region(size_t i, const ParallelCompactData::RegionData* c)
 223 {
 224 #define REGION_IDX_FORMAT        SIZE_FORMAT_W(7)
 225 #define REGION_DATA_FORMAT       SIZE_FORMAT_W(5)
 226 
 227   ParallelCompactData& sd = PSParallelCompact::summary_data();
 228   size_t dci = c->destination() ? sd.addr_to_region_idx(c->destination()) : 0;
 229   log_develop_trace(gc, compaction)(
 230       REGION_IDX_FORMAT " " PTR_FORMAT " "
 231       REGION_IDX_FORMAT " " PTR_FORMAT " "
 232       REGION_DATA_FORMAT " " REGION_DATA_FORMAT " "
 233       REGION_DATA_FORMAT " " REGION_IDX_FORMAT " %d",
 234       i, p2i(c->data_location()), dci, p2i(c->destination()),
 235       c->partial_obj_size(), c->live_obj_size(),
 236       c->data_size(), c->source_region(), c->destination_count());
 237 
 238 #undef  REGION_IDX_FORMAT
 239 #undef  REGION_DATA_FORMAT
 240 }
 241 
 242 void
 243 print_generic_summary_data(ParallelCompactData& summary_data,
 244                            HeapWord* const beg_addr,
 245                            HeapWord* const end_addr)
 246 {
 247   size_t total_words = 0;
 248   size_t i = summary_data.addr_to_region_idx(beg_addr);
 249   const size_t last = summary_data.addr_to_region_idx(end_addr);
 250   HeapWord* pdest = 0;
 251 
 252   while (i < last) {
 253     ParallelCompactData::RegionData* c = summary_data.region(i);
 254     if (c->data_size() != 0 || c->destination() != pdest) {
 255       print_generic_summary_region(i, c);
 256       total_words += c->data_size();
 257       pdest = c->destination();
 258     }
 259     ++i;
 260   }
 261 
 262   log_develop_trace(gc, compaction)("summary_data_bytes=" SIZE_FORMAT, total_words * HeapWordSize);
 263 }
 264 
 265 void
 266 print_generic_summary_data(ParallelCompactData& summary_data,
 267                            SpaceInfo* space_info)
 268 {
 269   if (!log_develop_is_enabled(Trace, gc, compaction)) {
 270     return;
 271   }
 272 
 273   for (unsigned int id = 0; id < PSParallelCompact::last_space_id; ++id) {
 274     const MutableSpace* space = space_info[id].space();
 275     print_generic_summary_data(summary_data, space->bottom(),
 276                                MAX2(space->top(), space_info[id].new_top()));
 277   }
 278 }
 279 
 280 void
 281 print_initial_summary_data(ParallelCompactData& summary_data,
 282                            const MutableSpace* space) {
 283   if (space->top() == space->bottom()) {
 284     return;
 285   }
 286 
 287   const size_t region_size = ParallelCompactData::RegionSize;
 288   typedef ParallelCompactData::RegionData RegionData;
 289   HeapWord* const top_aligned_up = summary_data.region_align_up(space->top());
 290   const size_t end_region = summary_data.addr_to_region_idx(top_aligned_up);
 291   const RegionData* c = summary_data.region(end_region - 1);
 292   HeapWord* end_addr = c->destination() + c->data_size();
 293   const size_t live_in_space = pointer_delta(end_addr, space->bottom());
 294 
 295   // Print (and count) the full regions at the beginning of the space.
 296   size_t full_region_count = 0;
 297   size_t i = summary_data.addr_to_region_idx(space->bottom());
 298   while (i < end_region && summary_data.region(i)->data_size() == region_size) {
 299     ParallelCompactData::RegionData* c = summary_data.region(i);
 300     log_develop_trace(gc, compaction)(
 301         SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d",
 302         i, p2i(c->destination()),
 303         c->partial_obj_size(), c->live_obj_size(),
 304         c->data_size(), c->source_region(), c->destination_count());
 305     ++full_region_count;
 306     ++i;
 307   }
 308 
 309   size_t live_to_right = live_in_space - full_region_count * region_size;
 310 
 311   double max_reclaimed_ratio = 0.0;
 312   size_t max_reclaimed_ratio_region = 0;
 313   size_t max_dead_to_right = 0;
 314   size_t max_live_to_right = 0;
 315 
 316   // Print the 'reclaimed ratio' for regions while there is something live in
 317   // the region or to the right of it.  The remaining regions are empty (and
 318   // uninteresting), and computing the ratio will result in division by 0.
 319   while (i < end_region && live_to_right > 0) {
 320     c = summary_data.region(i);
 321     HeapWord* const region_addr = summary_data.region_to_addr(i);
 322     const size_t used_to_right = pointer_delta(space->top(), region_addr);
 323     const size_t dead_to_right = used_to_right - live_to_right;
 324     const double reclaimed_ratio = double(dead_to_right) / live_to_right;
 325 
 326     if (reclaimed_ratio > max_reclaimed_ratio) {
 327             max_reclaimed_ratio = reclaimed_ratio;
 328             max_reclaimed_ratio_region = i;
 329             max_dead_to_right = dead_to_right;
 330             max_live_to_right = live_to_right;
 331     }
 332 
 333     ParallelCompactData::RegionData* c = summary_data.region(i);
 334     log_develop_trace(gc, compaction)(
 335         SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d"
 336         "%12.10f " SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10),
 337         i, p2i(c->destination()),
 338         c->partial_obj_size(), c->live_obj_size(),
 339         c->data_size(), c->source_region(), c->destination_count(),
 340         reclaimed_ratio, dead_to_right, live_to_right);
 341 
 342 
 343     live_to_right -= c->data_size();
 344     ++i;
 345   }
 346 
 347   // Any remaining regions are empty.  Print one more if there is one.
 348   if (i < end_region) {
 349     ParallelCompactData::RegionData* c = summary_data.region(i);
 350     log_develop_trace(gc, compaction)(
 351         SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d",
 352          i, p2i(c->destination()),
 353          c->partial_obj_size(), c->live_obj_size(),
 354          c->data_size(), c->source_region(), c->destination_count());
 355   }
 356 
 357   log_develop_trace(gc, compaction)("max:  " SIZE_FORMAT_W(4) " d2r=" SIZE_FORMAT_W(10) " l2r=" SIZE_FORMAT_W(10) " max_ratio=%14.12f",
 358                                     max_reclaimed_ratio_region, max_dead_to_right, max_live_to_right, max_reclaimed_ratio);
 359 }
 360 
 361 void
 362 print_initial_summary_data(ParallelCompactData& summary_data,
 363                            SpaceInfo* space_info) {
 364   if (!log_develop_is_enabled(Trace, gc, compaction)) {
 365     return;
 366   }
 367 
 368   unsigned int id = PSParallelCompact::old_space_id;
 369   const MutableSpace* space;
 370   do {
 371     space = space_info[id].space();
 372     print_initial_summary_data(summary_data, space);
 373   } while (++id < PSParallelCompact::eden_space_id);
 374 
 375   do {
 376     space = space_info[id].space();
 377     print_generic_summary_data(summary_data, space->bottom(), space->top());
 378   } while (++id < PSParallelCompact::last_space_id);
 379 }
 380 
 381 void ParallelCompact_test() {
 382   if (!UseParallelOldGC) {
 383     return;
 384   }
 385   // Check that print_generic_summary_data() does not print the
 386   // end region by placing a bad value in the destination of the
 387   // end region.  The end region should not be printed because it
 388   // corresponds to the space after the end of the heap.
 389   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
 390   ParCompactionManager* const vmthread_cm =
 391     ParCompactionManager::manager_array(ParallelGCThreads);
 392   HeapWord* begin_heap =
 393     (HeapWord*) heap->old_gen()->virtual_space()->low_boundary();
 394   HeapWord* end_heap =
 395     (HeapWord*) heap->young_gen()->virtual_space()->high_boundary();
 396 
 397   print_generic_summary_data(PSParallelCompact::summary_data(),
 398     begin_heap, end_heap);
 399 }
 400 #endif  // #ifndef PRODUCT
 401 
 402 #ifdef  ASSERT
 403 size_t add_obj_count;
 404 size_t add_obj_size;
 405 size_t mark_bitmap_count;
 406 size_t mark_bitmap_size;
 407 #endif  // #ifdef ASSERT
 408 
 409 ParallelCompactData::ParallelCompactData()
 410 {
 411   _region_start = 0;
 412 
 413   _region_vspace = 0;
 414   _reserved_byte_size = 0;
 415   _region_data = 0;
 416   _region_count = 0;
 417 
 418   _block_vspace = 0;
 419   _block_data = 0;
 420   _block_count = 0;
 421 }
 422 
 423 bool ParallelCompactData::initialize(MemRegion covered_region)
 424 {
 425   _region_start = covered_region.start();
 426   const size_t region_size = covered_region.word_size();
 427   DEBUG_ONLY(_region_end = _region_start + region_size;)
 428 
 429   assert(region_align_down(_region_start) == _region_start,
 430          "region start not aligned");
 431   assert((region_size & RegionSizeOffsetMask) == 0,
 432          "region size not a multiple of RegionSize");
 433 
 434   bool result = initialize_region_data(region_size) && initialize_block_data();
 435   return result;
 436 }
 437 
 438 PSVirtualSpace*
 439 ParallelCompactData::create_vspace(size_t count, size_t element_size)
 440 {
 441   const size_t raw_bytes = count * element_size;
 442   const size_t page_sz = os::page_size_for_region_aligned(raw_bytes, 10);
 443   const size_t granularity = os::vm_allocation_granularity();
 444   _reserved_byte_size = align_size_up(raw_bytes, MAX2(page_sz, granularity));
 445 
 446   const size_t rs_align = page_sz == (size_t) os::vm_page_size() ? 0 :
 447     MAX2(page_sz, granularity);
 448   ReservedSpace rs(_reserved_byte_size, rs_align, rs_align > 0);
 449   os::trace_page_sizes("Parallel Compact Data", raw_bytes, raw_bytes, page_sz, rs.base(),
 450                        rs.size());
 451 
 452   MemTracker::record_virtual_memory_type((address)rs.base(), mtGC);
 453 
 454   PSVirtualSpace* vspace = new PSVirtualSpace(rs, page_sz);
 455   if (vspace != 0) {
 456     if (vspace->expand_by(_reserved_byte_size)) {
 457       return vspace;
 458     }
 459     delete vspace;
 460     // Release memory reserved in the space.
 461     rs.release();
 462   }
 463 
 464   return 0;
 465 }
 466 
 467 bool ParallelCompactData::initialize_region_data(size_t region_size)
 468 {
 469   const size_t count = (region_size + RegionSizeOffsetMask) >> Log2RegionSize;
 470   _region_vspace = create_vspace(count, sizeof(RegionData));
 471   if (_region_vspace != 0) {
 472     _region_data = (RegionData*)_region_vspace->reserved_low_addr();
 473     _region_count = count;
 474     return true;
 475   }
 476   return false;
 477 }
 478 
 479 bool ParallelCompactData::initialize_block_data()
 480 {
 481   assert(_region_count != 0, "region data must be initialized first");
 482   const size_t count = _region_count << Log2BlocksPerRegion;
 483   _block_vspace = create_vspace(count, sizeof(BlockData));
 484   if (_block_vspace != 0) {
 485     _block_data = (BlockData*)_block_vspace->reserved_low_addr();
 486     _block_count = count;
 487     return true;
 488   }
 489   return false;
 490 }
 491 
 492 void ParallelCompactData::clear()
 493 {
 494   memset(_region_data, 0, _region_vspace->committed_size());
 495   memset(_block_data, 0, _block_vspace->committed_size());
 496 }
 497 
 498 void ParallelCompactData::clear_range(size_t beg_region, size_t end_region) {
 499   assert(beg_region <= _region_count, "beg_region out of range");
 500   assert(end_region <= _region_count, "end_region out of range");
 501   assert(RegionSize % BlockSize == 0, "RegionSize not a multiple of BlockSize");
 502 
 503   const size_t region_cnt = end_region - beg_region;
 504   memset(_region_data + beg_region, 0, region_cnt * sizeof(RegionData));
 505 
 506   const size_t beg_block = beg_region * BlocksPerRegion;
 507   const size_t block_cnt = region_cnt * BlocksPerRegion;
 508   memset(_block_data + beg_block, 0, block_cnt * sizeof(BlockData));
 509 }
 510 
 511 HeapWord* ParallelCompactData::partial_obj_end(size_t region_idx) const
 512 {
 513   const RegionData* cur_cp = region(region_idx);
 514   const RegionData* const end_cp = region(region_count() - 1);
 515 
 516   HeapWord* result = region_to_addr(region_idx);
 517   if (cur_cp < end_cp) {
 518     do {
 519       result += cur_cp->partial_obj_size();
 520     } while (cur_cp->partial_obj_size() == RegionSize && ++cur_cp < end_cp);
 521   }
 522   return result;
 523 }
 524 
 525 void ParallelCompactData::add_obj(HeapWord* addr, size_t len)
 526 {
 527   const size_t obj_ofs = pointer_delta(addr, _region_start);
 528   const size_t beg_region = obj_ofs >> Log2RegionSize;
 529   const size_t end_region = (obj_ofs + len - 1) >> Log2RegionSize;
 530 
 531   DEBUG_ONLY(Atomic::inc_ptr(&add_obj_count);)
 532   DEBUG_ONLY(Atomic::add_ptr(len, &add_obj_size);)
 533 
 534   if (beg_region == end_region) {
 535     // All in one region.
 536     _region_data[beg_region].add_live_obj(len);
 537     return;
 538   }
 539 
 540   // First region.
 541   const size_t beg_ofs = region_offset(addr);
 542   _region_data[beg_region].add_live_obj(RegionSize - beg_ofs);
 543 
 544   Klass* klass = ((oop)addr)->klass();
 545   // Middle regions--completely spanned by this object.
 546   for (size_t region = beg_region + 1; region < end_region; ++region) {
 547     _region_data[region].set_partial_obj_size(RegionSize);
 548     _region_data[region].set_partial_obj_addr(addr);
 549   }
 550 
 551   // Last region.
 552   const size_t end_ofs = region_offset(addr + len - 1);
 553   _region_data[end_region].set_partial_obj_size(end_ofs + 1);
 554   _region_data[end_region].set_partial_obj_addr(addr);
 555 }
 556 
 557 void
 558 ParallelCompactData::summarize_dense_prefix(HeapWord* beg, HeapWord* end)
 559 {
 560   assert(region_offset(beg) == 0, "not RegionSize aligned");
 561   assert(region_offset(end) == 0, "not RegionSize aligned");
 562 
 563   size_t cur_region = addr_to_region_idx(beg);
 564   const size_t end_region = addr_to_region_idx(end);
 565   HeapWord* addr = beg;
 566   while (cur_region < end_region) {
 567     _region_data[cur_region].set_destination(addr);
 568     _region_data[cur_region].set_destination_count(0);
 569     _region_data[cur_region].set_source_region(cur_region);
 570     _region_data[cur_region].set_data_location(addr);
 571 
 572     // Update live_obj_size so the region appears completely full.
 573     size_t live_size = RegionSize - _region_data[cur_region].partial_obj_size();
 574     _region_data[cur_region].set_live_obj_size(live_size);
 575 
 576     ++cur_region;
 577     addr += RegionSize;
 578   }
 579 }
 580 
 581 // Find the point at which a space can be split and, if necessary, record the
 582 // split point.
 583 //
 584 // If the current src region (which overflowed the destination space) doesn't
 585 // have a partial object, the split point is at the beginning of the current src
 586 // region (an "easy" split, no extra bookkeeping required).
 587 //
 588 // If the current src region has a partial object, the split point is in the
 589 // region where that partial object starts (call it the split_region).  If
 590 // split_region has a partial object, then the split point is just after that
 591 // partial object (a "hard" split where we have to record the split data and
 592 // zero the partial_obj_size field).  With a "hard" split, we know that the
 593 // partial_obj ends within split_region because the partial object that caused
 594 // the overflow starts in split_region.  If split_region doesn't have a partial
 595 // obj, then the split is at the beginning of split_region (another "easy"
 596 // split).
 597 HeapWord*
 598 ParallelCompactData::summarize_split_space(size_t src_region,
 599                                            SplitInfo& split_info,
 600                                            HeapWord* destination,
 601                                            HeapWord* target_end,
 602                                            HeapWord** target_next)
 603 {
 604   assert(destination <= target_end, "sanity");
 605   assert(destination + _region_data[src_region].data_size() > target_end,
 606     "region should not fit into target space");
 607   assert(is_region_aligned(target_end), "sanity");
 608 
 609   size_t split_region = src_region;
 610   HeapWord* split_destination = destination;
 611   size_t partial_obj_size = _region_data[src_region].partial_obj_size();
 612 
 613   if (destination + partial_obj_size > target_end) {
 614     // The split point is just after the partial object (if any) in the
 615     // src_region that contains the start of the object that overflowed the
 616     // destination space.
 617     //
 618     // Find the start of the "overflow" object and set split_region to the
 619     // region containing it.
 620     HeapWord* const overflow_obj = _region_data[src_region].partial_obj_addr();
 621     split_region = addr_to_region_idx(overflow_obj);
 622 
 623     // Clear the source_region field of all destination regions whose first word
 624     // came from data after the split point (a non-null source_region field
 625     // implies a region must be filled).
 626     //
 627     // An alternative to the simple loop below:  clear during post_compact(),
 628     // which uses memcpy instead of individual stores, and is easy to
 629     // parallelize.  (The downside is that it clears the entire RegionData
 630     // object as opposed to just one field.)
 631     //
 632     // post_compact() would have to clear the summary data up to the highest
 633     // address that was written during the summary phase, which would be
 634     //
 635     //         max(top, max(new_top, clear_top))
 636     //
 637     // where clear_top is a new field in SpaceInfo.  Would have to set clear_top
 638     // to target_end.
 639     const RegionData* const sr = region(split_region);
 640     const size_t beg_idx =
 641       addr_to_region_idx(region_align_up(sr->destination() +
 642                                          sr->partial_obj_size()));
 643     const size_t end_idx = addr_to_region_idx(target_end);
 644 
 645     log_develop_trace(gc, compaction)("split:  clearing source_region field in [" SIZE_FORMAT ", " SIZE_FORMAT ")", beg_idx, end_idx);
 646     for (size_t idx = beg_idx; idx < end_idx; ++idx) {
 647       _region_data[idx].set_source_region(0);
 648     }
 649 
 650     // Set split_destination and partial_obj_size to reflect the split region.
 651     split_destination = sr->destination();
 652     partial_obj_size = sr->partial_obj_size();
 653   }
 654 
 655   // The split is recorded only if a partial object extends onto the region.
 656   if (partial_obj_size != 0) {
 657     _region_data[split_region].set_partial_obj_size(0);
 658     split_info.record(split_region, partial_obj_size, split_destination);
 659   }
 660 
 661   // Setup the continuation addresses.
 662   *target_next = split_destination + partial_obj_size;
 663   HeapWord* const source_next = region_to_addr(split_region) + partial_obj_size;
 664 
 665   if (log_develop_is_enabled(Trace, gc, compaction)) {
 666     const char * split_type = partial_obj_size == 0 ? "easy" : "hard";
 667     log_develop_trace(gc, compaction)("%s split:  src=" PTR_FORMAT " src_c=" SIZE_FORMAT " pos=" SIZE_FORMAT,
 668                                       split_type, p2i(source_next), split_region, partial_obj_size);
 669     log_develop_trace(gc, compaction)("%s split:  dst=" PTR_FORMAT " dst_c=" SIZE_FORMAT " tn=" PTR_FORMAT,
 670                                       split_type, p2i(split_destination),
 671                                       addr_to_region_idx(split_destination),
 672                                       p2i(*target_next));
 673 
 674     if (partial_obj_size != 0) {
 675       HeapWord* const po_beg = split_info.destination();
 676       HeapWord* const po_end = po_beg + split_info.partial_obj_size();
 677       log_develop_trace(gc, compaction)("%s split:  po_beg=" PTR_FORMAT " " SIZE_FORMAT " po_end=" PTR_FORMAT " " SIZE_FORMAT,
 678                                         split_type,
 679                                         p2i(po_beg), addr_to_region_idx(po_beg),
 680                                         p2i(po_end), addr_to_region_idx(po_end));
 681     }
 682   }
 683 
 684   return source_next;
 685 }
 686 
 687 bool ParallelCompactData::summarize(SplitInfo& split_info,
 688                                     HeapWord* source_beg, HeapWord* source_end,
 689                                     HeapWord** source_next,
 690                                     HeapWord* target_beg, HeapWord* target_end,
 691                                     HeapWord** target_next)
 692 {
 693   HeapWord* const source_next_val = source_next == NULL ? NULL : *source_next;
 694   log_develop_trace(gc, compaction)(
 695       "sb=" PTR_FORMAT " se=" PTR_FORMAT " sn=" PTR_FORMAT
 696       "tb=" PTR_FORMAT " te=" PTR_FORMAT " tn=" PTR_FORMAT,
 697       p2i(source_beg), p2i(source_end), p2i(source_next_val),
 698       p2i(target_beg), p2i(target_end), p2i(*target_next));
 699 
 700   size_t cur_region = addr_to_region_idx(source_beg);
 701   const size_t end_region = addr_to_region_idx(region_align_up(source_end));
 702 
 703   HeapWord *dest_addr = target_beg;
 704   while (cur_region < end_region) {
 705     // The destination must be set even if the region has no data.
 706     _region_data[cur_region].set_destination(dest_addr);
 707 
 708     size_t words = _region_data[cur_region].data_size();
 709     if (words > 0) {
 710       // If cur_region does not fit entirely into the target space, find a point
 711       // at which the source space can be 'split' so that part is copied to the
 712       // target space and the rest is copied elsewhere.
 713       if (dest_addr + words > target_end) {
 714         assert(source_next != NULL, "source_next is NULL when splitting");
 715         *source_next = summarize_split_space(cur_region, split_info, dest_addr,
 716                                              target_end, target_next);
 717         return false;
 718       }
 719 
 720       // Compute the destination_count for cur_region, and if necessary, update
 721       // source_region for a destination region.  The source_region field is
 722       // updated if cur_region is the first (left-most) region to be copied to a
 723       // destination region.
 724       //
 725       // The destination_count calculation is a bit subtle.  A region that has
 726       // data that compacts into itself does not count itself as a destination.
 727       // This maintains the invariant that a zero count means the region is
 728       // available and can be claimed and then filled.
 729       uint destination_count = 0;
 730       if (split_info.is_split(cur_region)) {
 731         // The current region has been split:  the partial object will be copied
 732         // to one destination space and the remaining data will be copied to
 733         // another destination space.  Adjust the initial destination_count and,
 734         // if necessary, set the source_region field if the partial object will
 735         // cross a destination region boundary.
 736         destination_count = split_info.destination_count();
 737         if (destination_count == 2) {
 738           size_t dest_idx = addr_to_region_idx(split_info.dest_region_addr());
 739           _region_data[dest_idx].set_source_region(cur_region);
 740         }
 741       }
 742 
 743       HeapWord* const last_addr = dest_addr + words - 1;
 744       const size_t dest_region_1 = addr_to_region_idx(dest_addr);
 745       const size_t dest_region_2 = addr_to_region_idx(last_addr);
 746 
 747       // Initially assume that the destination regions will be the same and
 748       // adjust the value below if necessary.  Under this assumption, if
 749       // cur_region == dest_region_2, then cur_region will be compacted
 750       // completely into itself.
 751       destination_count += cur_region == dest_region_2 ? 0 : 1;
 752       if (dest_region_1 != dest_region_2) {
 753         // Destination regions differ; adjust destination_count.
 754         destination_count += 1;
 755         // Data from cur_region will be copied to the start of dest_region_2.
 756         _region_data[dest_region_2].set_source_region(cur_region);
 757       } else if (region_offset(dest_addr) == 0) {
 758         // Data from cur_region will be copied to the start of the destination
 759         // region.
 760         _region_data[dest_region_1].set_source_region(cur_region);
 761       }
 762 
 763       _region_data[cur_region].set_destination_count(destination_count);
 764       _region_data[cur_region].set_data_location(region_to_addr(cur_region));
 765       dest_addr += words;
 766     }
 767 
 768     ++cur_region;
 769   }
 770 
 771   *target_next = dest_addr;
 772   return true;
 773 }
 774 
 775 HeapWord* ParallelCompactData::calc_new_pointer(HeapWord* addr, ParCompactionManager* cm) {
 776   assert(addr != NULL, "Should detect NULL oop earlier");
 777   assert(ParallelScavengeHeap::heap()->is_in(addr), "not in heap");
 778   assert(PSParallelCompact::mark_bitmap()->is_marked(addr), "not marked");
 779 
 780   // Region covering the object.
 781   RegionData* const region_ptr = addr_to_region_ptr(addr);
 782   HeapWord* result = region_ptr->destination();
 783 
 784   // If the entire Region is live, the new location is region->destination + the
 785   // offset of the object within in the Region.
 786 
 787   // Run some performance tests to determine if this special case pays off.  It
 788   // is worth it for pointers into the dense prefix.  If the optimization to
 789   // avoid pointer updates in regions that only point to the dense prefix is
 790   // ever implemented, this should be revisited.
 791   if (region_ptr->data_size() == RegionSize) {
 792     result += region_offset(addr);
 793     return result;
 794   }
 795 
 796   // Otherwise, the new location is region->destination + block offset + the
 797   // number of live words in the Block that are (a) to the left of addr and (b)
 798   // due to objects that start in the Block.
 799 
 800   // Fill in the block table if necessary.  This is unsynchronized, so multiple
 801   // threads may fill the block table for a region (harmless, since it is
 802   // idempotent).
 803   if (!region_ptr->blocks_filled()) {
 804     PSParallelCompact::fill_blocks(addr_to_region_idx(addr));
 805     region_ptr->set_blocks_filled();
 806   }
 807 
 808   HeapWord* const search_start = block_align_down(addr);
 809   const size_t block_offset = addr_to_block_ptr(addr)->offset();
 810 
 811   const ParMarkBitMap* bitmap = PSParallelCompact::mark_bitmap();
 812   const size_t live = bitmap->live_words_in_range(cm, search_start, oop(addr));
 813   result += block_offset + live;
 814   DEBUG_ONLY(PSParallelCompact::check_new_location(addr, result));
 815   return result;
 816 }
 817 
 818 #ifdef ASSERT
 819 void ParallelCompactData::verify_clear(const PSVirtualSpace* vspace)
 820 {
 821   const size_t* const beg = (const size_t*)vspace->committed_low_addr();
 822   const size_t* const end = (const size_t*)vspace->committed_high_addr();
 823   for (const size_t* p = beg; p < end; ++p) {
 824     assert(*p == 0, "not zero");
 825   }
 826 }
 827 
 828 void ParallelCompactData::verify_clear()
 829 {
 830   verify_clear(_region_vspace);
 831   verify_clear(_block_vspace);
 832 }
 833 #endif  // #ifdef ASSERT
 834 
 835 STWGCTimer          PSParallelCompact::_gc_timer;
 836 ParallelOldTracer   PSParallelCompact::_gc_tracer;
 837 elapsedTimer        PSParallelCompact::_accumulated_time;
 838 unsigned int        PSParallelCompact::_total_invocations = 0;
 839 unsigned int        PSParallelCompact::_maximum_compaction_gc_num = 0;
 840 jlong               PSParallelCompact::_time_of_last_gc = 0;
 841 CollectorCounters*  PSParallelCompact::_counters = NULL;
 842 ParMarkBitMap       PSParallelCompact::_mark_bitmap;
 843 ParallelCompactData PSParallelCompact::_summary_data;
 844 
 845 PSParallelCompact::IsAliveClosure PSParallelCompact::_is_alive_closure;
 846 
 847 bool PSParallelCompact::IsAliveClosure::do_object_b(oop p) { return mark_bitmap()->is_marked(p); }
 848 
 849 void PSParallelCompact::AdjustKlassClosure::do_klass(Klass* klass) {
 850   PSParallelCompact::AdjustPointerClosure closure(_cm);
 851   klass->oops_do(&closure);
 852 }
 853 
 854 void PSParallelCompact::post_initialize() {
 855   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
 856   MemRegion mr = heap->reserved_region();
 857   _ref_processor =
 858     new ReferenceProcessor(mr,            // span
 859                            ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing
 860                            ParallelGCThreads, // mt processing degree
 861                            true,              // mt discovery
 862                            ParallelGCThreads, // mt discovery degree
 863                            true,              // atomic_discovery
 864                            &_is_alive_closure); // non-header is alive closure
 865   _counters = new CollectorCounters("PSParallelCompact", 1);
 866 
 867   // Initialize static fields in ParCompactionManager.
 868   ParCompactionManager::initialize(mark_bitmap());
 869 }
 870 
 871 bool PSParallelCompact::initialize() {
 872   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
 873   MemRegion mr = heap->reserved_region();
 874 
 875   // Was the old gen get allocated successfully?
 876   if (!heap->old_gen()->is_allocated()) {
 877     return false;
 878   }
 879 
 880   initialize_space_info();
 881   initialize_dead_wood_limiter();
 882 
 883   if (!_mark_bitmap.initialize(mr)) {
 884     vm_shutdown_during_initialization(
 885       err_msg("Unable to allocate " SIZE_FORMAT "KB bitmaps for parallel "
 886       "garbage collection for the requested " SIZE_FORMAT "KB heap.",
 887       _mark_bitmap.reserved_byte_size()/K, mr.byte_size()/K));
 888     return false;
 889   }
 890 
 891   if (!_summary_data.initialize(mr)) {
 892     vm_shutdown_during_initialization(
 893       err_msg("Unable to allocate " SIZE_FORMAT "KB card tables for parallel "
 894       "garbage collection for the requested " SIZE_FORMAT "KB heap.",
 895       _summary_data.reserved_byte_size()/K, mr.byte_size()/K));
 896     return false;
 897   }
 898 
 899   return true;
 900 }
 901 
 902 void PSParallelCompact::initialize_space_info()
 903 {
 904   memset(&_space_info, 0, sizeof(_space_info));
 905 
 906   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
 907   PSYoungGen* young_gen = heap->young_gen();
 908 
 909   _space_info[old_space_id].set_space(heap->old_gen()->object_space());
 910   _space_info[eden_space_id].set_space(young_gen->eden_space());
 911   _space_info[from_space_id].set_space(young_gen->from_space());
 912   _space_info[to_space_id].set_space(young_gen->to_space());
 913 
 914   _space_info[old_space_id].set_start_array(heap->old_gen()->start_array());
 915 }
 916 
 917 void PSParallelCompact::initialize_dead_wood_limiter()
 918 {
 919   const size_t max = 100;
 920   _dwl_mean = double(MIN2(ParallelOldDeadWoodLimiterMean, max)) / 100.0;
 921   _dwl_std_dev = double(MIN2(ParallelOldDeadWoodLimiterStdDev, max)) / 100.0;
 922   _dwl_first_term = 1.0 / (sqrt(2.0 * M_PI) * _dwl_std_dev);
 923   DEBUG_ONLY(_dwl_initialized = true;)
 924   _dwl_adjustment = normal_distribution(1.0);
 925 }
 926 
 927 void
 928 PSParallelCompact::clear_data_covering_space(SpaceId id)
 929 {
 930   // At this point, top is the value before GC, new_top() is the value that will
 931   // be set at the end of GC.  The marking bitmap is cleared to top; nothing
 932   // should be marked above top.  The summary data is cleared to the larger of
 933   // top & new_top.
 934   MutableSpace* const space = _space_info[id].space();
 935   HeapWord* const bot = space->bottom();
 936   HeapWord* const top = space->top();
 937   HeapWord* const max_top = MAX2(top, _space_info[id].new_top());
 938 
 939   const idx_t beg_bit = _mark_bitmap.addr_to_bit(bot);
 940   const idx_t end_bit = BitMap::word_align_up(_mark_bitmap.addr_to_bit(top));
 941   _mark_bitmap.clear_range(beg_bit, end_bit);
 942 
 943   const size_t beg_region = _summary_data.addr_to_region_idx(bot);
 944   const size_t end_region =
 945     _summary_data.addr_to_region_idx(_summary_data.region_align_up(max_top));
 946   _summary_data.clear_range(beg_region, end_region);
 947 
 948   // Clear the data used to 'split' regions.
 949   SplitInfo& split_info = _space_info[id].split_info();
 950   if (split_info.is_valid()) {
 951     split_info.clear();
 952   }
 953   DEBUG_ONLY(split_info.verify_clear();)
 954 }
 955 
 956 void PSParallelCompact::pre_compact()
 957 {
 958   // Update the from & to space pointers in space_info, since they are swapped
 959   // at each young gen gc.  Do the update unconditionally (even though a
 960   // promotion failure does not swap spaces) because an unknown number of young
 961   // collections will have swapped the spaces an unknown number of times.
 962   GCTraceTime(Debug, gc, phases) tm("Pre Compact", &_gc_timer);
 963   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
 964   _space_info[from_space_id].set_space(heap->young_gen()->from_space());
 965   _space_info[to_space_id].set_space(heap->young_gen()->to_space());
 966 
 967   DEBUG_ONLY(add_obj_count = add_obj_size = 0;)
 968   DEBUG_ONLY(mark_bitmap_count = mark_bitmap_size = 0;)
 969 
 970   // Increment the invocation count
 971   heap->increment_total_collections(true);
 972 
 973   // We need to track unique mark sweep invocations as well.
 974   _total_invocations++;
 975 
 976   heap->print_heap_before_gc();
 977   heap->trace_heap_before_gc(&_gc_tracer);
 978 
 979   // Fill in TLABs
 980   heap->accumulate_statistics_all_tlabs();
 981   heap->ensure_parsability(true);  // retire TLABs
 982 
 983   if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
 984     HandleMark hm;  // Discard invalid handles created during verification
 985     Universe::verify("Before GC");
 986   }
 987 
 988   // Verify object start arrays
 989   if (VerifyObjectStartArray &&
 990       VerifyBeforeGC) {
 991     heap->old_gen()->verify_object_start_array();
 992   }
 993 
 994   DEBUG_ONLY(mark_bitmap()->verify_clear();)
 995   DEBUG_ONLY(summary_data().verify_clear();)
 996 
 997   // Have worker threads release resources the next time they run a task.
 998   gc_task_manager()->release_all_resources();
 999 
1000   ParCompactionManager::reset_all_bitmap_query_caches();
1001 }
1002 
1003 void PSParallelCompact::post_compact()
1004 {
1005   GCTraceTime(Info, gc, phases) tm("Post Compact", &_gc_timer);
1006 
1007   for (unsigned int id = old_space_id; id < last_space_id; ++id) {
1008     // Clear the marking bitmap, summary data and split info.
1009     clear_data_covering_space(SpaceId(id));
1010     // Update top().  Must be done after clearing the bitmap and summary data.
1011     _space_info[id].publish_new_top();
1012   }
1013 
1014   MutableSpace* const eden_space = _space_info[eden_space_id].space();
1015   MutableSpace* const from_space = _space_info[from_space_id].space();
1016   MutableSpace* const to_space   = _space_info[to_space_id].space();
1017 
1018   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
1019   bool eden_empty = eden_space->is_empty();
1020   if (!eden_empty) {
1021     eden_empty = absorb_live_data_from_eden(heap->size_policy(),
1022                                             heap->young_gen(), heap->old_gen());
1023   }
1024 
1025   // Update heap occupancy information which is used as input to the soft ref
1026   // clearing policy at the next gc.
1027   Universe::update_heap_info_at_gc();
1028 
1029   bool young_gen_empty = eden_empty && from_space->is_empty() &&
1030     to_space->is_empty();
1031 
1032   ModRefBarrierSet* modBS = barrier_set_cast<ModRefBarrierSet>(heap->barrier_set());
1033   MemRegion old_mr = heap->old_gen()->reserved();
1034   if (young_gen_empty) {
1035     modBS->clear(MemRegion(old_mr.start(), old_mr.end()));
1036   } else {
1037     modBS->invalidate(MemRegion(old_mr.start(), old_mr.end()));
1038   }
1039 
1040   // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1041   ClassLoaderDataGraph::purge();
1042   MetaspaceAux::verify_metrics();
1043 
1044   CodeCache::gc_epilogue();
1045   JvmtiExport::gc_epilogue();
1046 
1047 #if defined(COMPILER2) || INCLUDE_JVMCI
1048   DerivedPointerTable::update_pointers();
1049 #endif
1050 
1051   ref_processor()->enqueue_discovered_references(NULL);
1052 
1053   if (ZapUnusedHeapArea) {
1054     heap->gen_mangle_unused_area();
1055   }
1056 
1057   // Update time of last GC
1058   reset_millis_since_last_gc();
1059 }
1060 
1061 HeapWord*
1062 PSParallelCompact::compute_dense_prefix_via_density(const SpaceId id,
1063                                                     bool maximum_compaction)
1064 {
1065   const size_t region_size = ParallelCompactData::RegionSize;
1066   const ParallelCompactData& sd = summary_data();
1067 
1068   const MutableSpace* const space = _space_info[id].space();
1069   HeapWord* const top_aligned_up = sd.region_align_up(space->top());
1070   const RegionData* const beg_cp = sd.addr_to_region_ptr(space->bottom());
1071   const RegionData* const end_cp = sd.addr_to_region_ptr(top_aligned_up);
1072 
1073   // Skip full regions at the beginning of the space--they are necessarily part
1074   // of the dense prefix.
1075   size_t full_count = 0;
1076   const RegionData* cp;
1077   for (cp = beg_cp; cp < end_cp && cp->data_size() == region_size; ++cp) {
1078     ++full_count;
1079   }
1080 
1081   assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");
1082   const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;
1083   const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval;
1084   if (maximum_compaction || cp == end_cp || interval_ended) {
1085     _maximum_compaction_gc_num = total_invocations();
1086     return sd.region_to_addr(cp);
1087   }
1088 
1089   HeapWord* const new_top = _space_info[id].new_top();
1090   const size_t space_live = pointer_delta(new_top, space->bottom());
1091   const size_t space_used = space->used_in_words();
1092   const size_t space_capacity = space->capacity_in_words();
1093 
1094   const double cur_density = double(space_live) / space_capacity;
1095   const double deadwood_density =
1096     (1.0 - cur_density) * (1.0 - cur_density) * cur_density * cur_density;
1097   const size_t deadwood_goal = size_t(space_capacity * deadwood_density);
1098 
1099   if (TraceParallelOldGCDensePrefix) {
1100     tty->print_cr("cur_dens=%5.3f dw_dens=%5.3f dw_goal=" SIZE_FORMAT,
1101                   cur_density, deadwood_density, deadwood_goal);
1102     tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " "
1103                   "space_cap=" SIZE_FORMAT,
1104                   space_live, space_used,
1105                   space_capacity);
1106   }
1107 
1108   // XXX - Use binary search?
1109   HeapWord* dense_prefix = sd.region_to_addr(cp);
1110   const RegionData* full_cp = cp;
1111   const RegionData* const top_cp = sd.addr_to_region_ptr(space->top() - 1);
1112   while (cp < end_cp) {
1113     HeapWord* region_destination = cp->destination();
1114     const size_t cur_deadwood = pointer_delta(dense_prefix, region_destination);
1115     if (TraceParallelOldGCDensePrefix && Verbose) {
1116       tty->print_cr("c#=" SIZE_FORMAT_W(4) " dst=" PTR_FORMAT " "
1117                     "dp=" PTR_FORMAT " " "cdw=" SIZE_FORMAT_W(8),
1118                     sd.region(cp), p2i(region_destination),
1119                     p2i(dense_prefix), cur_deadwood);
1120     }
1121 
1122     if (cur_deadwood >= deadwood_goal) {
1123       // Found the region that has the correct amount of deadwood to the left.
1124       // This typically occurs after crossing a fairly sparse set of regions, so
1125       // iterate backwards over those sparse regions, looking for the region
1126       // that has the lowest density of live objects 'to the right.'
1127       size_t space_to_left = sd.region(cp) * region_size;
1128       size_t live_to_left = space_to_left - cur_deadwood;
1129       size_t space_to_right = space_capacity - space_to_left;
1130       size_t live_to_right = space_live - live_to_left;
1131       double density_to_right = double(live_to_right) / space_to_right;
1132       while (cp > full_cp) {
1133         --cp;
1134         const size_t prev_region_live_to_right = live_to_right -
1135           cp->data_size();
1136         const size_t prev_region_space_to_right = space_to_right + region_size;
1137         double prev_region_density_to_right =
1138           double(prev_region_live_to_right) / prev_region_space_to_right;
1139         if (density_to_right <= prev_region_density_to_right) {
1140           return dense_prefix;
1141         }
1142         if (TraceParallelOldGCDensePrefix && Verbose) {
1143           tty->print_cr("backing up from c=" SIZE_FORMAT_W(4) " d2r=%10.8f "
1144                         "pc_d2r=%10.8f", sd.region(cp), density_to_right,
1145                         prev_region_density_to_right);
1146         }
1147         dense_prefix -= region_size;
1148         live_to_right = prev_region_live_to_right;
1149         space_to_right = prev_region_space_to_right;
1150         density_to_right = prev_region_density_to_right;
1151       }
1152       return dense_prefix;
1153     }
1154 
1155     dense_prefix += region_size;
1156     ++cp;
1157   }
1158 
1159   return dense_prefix;
1160 }
1161 
1162 #ifndef PRODUCT
1163 void PSParallelCompact::print_dense_prefix_stats(const char* const algorithm,
1164                                                  const SpaceId id,
1165                                                  const bool maximum_compaction,
1166                                                  HeapWord* const addr)
1167 {
1168   const size_t region_idx = summary_data().addr_to_region_idx(addr);
1169   RegionData* const cp = summary_data().region(region_idx);
1170   const MutableSpace* const space = _space_info[id].space();
1171   HeapWord* const new_top = _space_info[id].new_top();
1172 
1173   const size_t space_live = pointer_delta(new_top, space->bottom());
1174   const size_t dead_to_left = pointer_delta(addr, cp->destination());
1175   const size_t space_cap = space->capacity_in_words();
1176   const double dead_to_left_pct = double(dead_to_left) / space_cap;
1177   const size_t live_to_right = new_top - cp->destination();
1178   const size_t dead_to_right = space->top() - addr - live_to_right;
1179 
1180   tty->print_cr("%s=" PTR_FORMAT " dpc=" SIZE_FORMAT_W(5) " "
1181                 "spl=" SIZE_FORMAT " "
1182                 "d2l=" SIZE_FORMAT " d2l%%=%6.4f "
1183                 "d2r=" SIZE_FORMAT " l2r=" SIZE_FORMAT
1184                 " ratio=%10.8f",
1185                 algorithm, p2i(addr), region_idx,
1186                 space_live,
1187                 dead_to_left, dead_to_left_pct,
1188                 dead_to_right, live_to_right,
1189                 double(dead_to_right) / live_to_right);
1190 }
1191 #endif  // #ifndef PRODUCT
1192 
1193 // Return a fraction indicating how much of the generation can be treated as
1194 // "dead wood" (i.e., not reclaimed).  The function uses a normal distribution
1195 // based on the density of live objects in the generation to determine a limit,
1196 // which is then adjusted so the return value is min_percent when the density is
1197 // 1.
1198 //
1199 // The following table shows some return values for a different values of the
1200 // standard deviation (ParallelOldDeadWoodLimiterStdDev); the mean is 0.5 and
1201 // min_percent is 1.
1202 //
1203 //                          fraction allowed as dead wood
1204 //         -----------------------------------------------------------------
1205 // density std_dev=70 std_dev=75 std_dev=80 std_dev=85 std_dev=90 std_dev=95
1206 // ------- ---------- ---------- ---------- ---------- ---------- ----------
1207 // 0.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
1208 // 0.05000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
1209 // 0.10000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
1210 // 0.15000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
1211 // 0.20000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
1212 // 0.25000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
1213 // 0.30000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
1214 // 0.35000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
1215 // 0.40000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
1216 // 0.45000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
1217 // 0.50000 0.13832410 0.11599237 0.09847664 0.08456518 0.07338887 0.06431510
1218 // 0.55000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
1219 // 0.60000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
1220 // 0.65000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
1221 // 0.70000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
1222 // 0.75000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
1223 // 0.80000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
1224 // 0.85000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
1225 // 0.90000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
1226 // 0.95000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
1227 // 1.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
1228 
1229 double PSParallelCompact::dead_wood_limiter(double density, size_t min_percent)
1230 {
1231   assert(_dwl_initialized, "uninitialized");
1232 
1233   // The raw limit is the value of the normal distribution at x = density.
1234   const double raw_limit = normal_distribution(density);
1235 
1236   // Adjust the raw limit so it becomes the minimum when the density is 1.
1237   //
1238   // First subtract the adjustment value (which is simply the precomputed value
1239   // normal_distribution(1.0)); this yields a value of 0 when the density is 1.
1240   // Then add the minimum value, so the minimum is returned when the density is
1241   // 1.  Finally, prevent negative values, which occur when the mean is not 0.5.
1242   const double min = double(min_percent) / 100.0;
1243   const double limit = raw_limit - _dwl_adjustment + min;
1244   return MAX2(limit, 0.0);
1245 }
1246 
1247 ParallelCompactData::RegionData*
1248 PSParallelCompact::first_dead_space_region(const RegionData* beg,
1249                                            const RegionData* end)
1250 {
1251   const size_t region_size = ParallelCompactData::RegionSize;
1252   ParallelCompactData& sd = summary_data();
1253   size_t left = sd.region(beg);
1254   size_t right = end > beg ? sd.region(end) - 1 : left;
1255 
1256   // Binary search.
1257   while (left < right) {
1258     // Equivalent to (left + right) / 2, but does not overflow.
1259     const size_t middle = left + (right - left) / 2;
1260     RegionData* const middle_ptr = sd.region(middle);
1261     HeapWord* const dest = middle_ptr->destination();
1262     HeapWord* const addr = sd.region_to_addr(middle);
1263     assert(dest != NULL, "sanity");
1264     assert(dest <= addr, "must move left");
1265 
1266     if (middle > left && dest < addr) {
1267       right = middle - 1;
1268     } else if (middle < right && middle_ptr->data_size() == region_size) {
1269       left = middle + 1;
1270     } else {
1271       return middle_ptr;
1272     }
1273   }
1274   return sd.region(left);
1275 }
1276 
1277 ParallelCompactData::RegionData*
1278 PSParallelCompact::dead_wood_limit_region(const RegionData* beg,
1279                                           const RegionData* end,
1280                                           size_t dead_words)
1281 {
1282   ParallelCompactData& sd = summary_data();
1283   size_t left = sd.region(beg);
1284   size_t right = end > beg ? sd.region(end) - 1 : left;
1285 
1286   // Binary search.
1287   while (left < right) {
1288     // Equivalent to (left + right) / 2, but does not overflow.
1289     const size_t middle = left + (right - left) / 2;
1290     RegionData* const middle_ptr = sd.region(middle);
1291     HeapWord* const dest = middle_ptr->destination();
1292     HeapWord* const addr = sd.region_to_addr(middle);
1293     assert(dest != NULL, "sanity");
1294     assert(dest <= addr, "must move left");
1295 
1296     const size_t dead_to_left = pointer_delta(addr, dest);
1297     if (middle > left && dead_to_left > dead_words) {
1298       right = middle - 1;
1299     } else if (middle < right && dead_to_left < dead_words) {
1300       left = middle + 1;
1301     } else {
1302       return middle_ptr;
1303     }
1304   }
1305   return sd.region(left);
1306 }
1307 
1308 // The result is valid during the summary phase, after the initial summarization
1309 // of each space into itself, and before final summarization.
1310 inline double
1311 PSParallelCompact::reclaimed_ratio(const RegionData* const cp,
1312                                    HeapWord* const bottom,
1313                                    HeapWord* const top,
1314                                    HeapWord* const new_top)
1315 {
1316   ParallelCompactData& sd = summary_data();
1317 
1318   assert(cp != NULL, "sanity");
1319   assert(bottom != NULL, "sanity");
1320   assert(top != NULL, "sanity");
1321   assert(new_top != NULL, "sanity");
1322   assert(top >= new_top, "summary data problem?");
1323   assert(new_top > bottom, "space is empty; should not be here");
1324   assert(new_top >= cp->destination(), "sanity");
1325   assert(top >= sd.region_to_addr(cp), "sanity");
1326 
1327   HeapWord* const destination = cp->destination();
1328   const size_t dense_prefix_live  = pointer_delta(destination, bottom);
1329   const size_t compacted_region_live = pointer_delta(new_top, destination);
1330   const size_t compacted_region_used = pointer_delta(top,
1331                                                      sd.region_to_addr(cp));
1332   const size_t reclaimable = compacted_region_used - compacted_region_live;
1333 
1334   const double divisor = dense_prefix_live + 1.25 * compacted_region_live;
1335   return double(reclaimable) / divisor;
1336 }
1337 
1338 // Return the address of the end of the dense prefix, a.k.a. the start of the
1339 // compacted region.  The address is always on a region boundary.
1340 //
1341 // Completely full regions at the left are skipped, since no compaction can
1342 // occur in those regions.  Then the maximum amount of dead wood to allow is
1343 // computed, based on the density (amount live / capacity) of the generation;
1344 // the region with approximately that amount of dead space to the left is
1345 // identified as the limit region.  Regions between the last completely full
1346 // region and the limit region are scanned and the one that has the best
1347 // (maximum) reclaimed_ratio() is selected.
1348 HeapWord*
1349 PSParallelCompact::compute_dense_prefix(const SpaceId id,
1350                                         bool maximum_compaction)
1351 {
1352   const size_t region_size = ParallelCompactData::RegionSize;
1353   const ParallelCompactData& sd = summary_data();
1354 
1355   const MutableSpace* const space = _space_info[id].space();
1356   HeapWord* const top = space->top();
1357   HeapWord* const top_aligned_up = sd.region_align_up(top);
1358   HeapWord* const new_top = _space_info[id].new_top();
1359   HeapWord* const new_top_aligned_up = sd.region_align_up(new_top);
1360   HeapWord* const bottom = space->bottom();
1361   const RegionData* const beg_cp = sd.addr_to_region_ptr(bottom);
1362   const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
1363   const RegionData* const new_top_cp =
1364     sd.addr_to_region_ptr(new_top_aligned_up);
1365 
1366   // Skip full regions at the beginning of the space--they are necessarily part
1367   // of the dense prefix.
1368   const RegionData* const full_cp = first_dead_space_region(beg_cp, new_top_cp);
1369   assert(full_cp->destination() == sd.region_to_addr(full_cp) ||
1370          space->is_empty(), "no dead space allowed to the left");
1371   assert(full_cp->data_size() < region_size || full_cp == new_top_cp - 1,
1372          "region must have dead space");
1373 
1374   // The gc number is saved whenever a maximum compaction is done, and used to
1375   // determine when the maximum compaction interval has expired.  This avoids
1376   // successive max compactions for different reasons.
1377   assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");
1378   const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;
1379   const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval ||
1380     total_invocations() == HeapFirstMaximumCompactionCount;
1381   if (maximum_compaction || full_cp == top_cp || interval_ended) {
1382     _maximum_compaction_gc_num = total_invocations();
1383     return sd.region_to_addr(full_cp);
1384   }
1385 
1386   const size_t space_live = pointer_delta(new_top, bottom);
1387   const size_t space_used = space->used_in_words();
1388   const size_t space_capacity = space->capacity_in_words();
1389 
1390   const double density = double(space_live) / double(space_capacity);
1391   const size_t min_percent_free = MarkSweepDeadRatio;
1392   const double limiter = dead_wood_limiter(density, min_percent_free);
1393   const size_t dead_wood_max = space_used - space_live;
1394   const size_t dead_wood_limit = MIN2(size_t(space_capacity * limiter),
1395                                       dead_wood_max);
1396 
1397   if (TraceParallelOldGCDensePrefix) {
1398     tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " "
1399                   "space_cap=" SIZE_FORMAT,
1400                   space_live, space_used,
1401                   space_capacity);
1402     tty->print_cr("dead_wood_limiter(%6.4f, " SIZE_FORMAT ")=%6.4f "
1403                   "dead_wood_max=" SIZE_FORMAT " dead_wood_limit=" SIZE_FORMAT,
1404                   density, min_percent_free, limiter,
1405                   dead_wood_max, dead_wood_limit);
1406   }
1407 
1408   // Locate the region with the desired amount of dead space to the left.
1409   const RegionData* const limit_cp =
1410     dead_wood_limit_region(full_cp, top_cp, dead_wood_limit);
1411 
1412   // Scan from the first region with dead space to the limit region and find the
1413   // one with the best (largest) reclaimed ratio.
1414   double best_ratio = 0.0;
1415   const RegionData* best_cp = full_cp;
1416   for (const RegionData* cp = full_cp; cp < limit_cp; ++cp) {
1417     double tmp_ratio = reclaimed_ratio(cp, bottom, top, new_top);
1418     if (tmp_ratio > best_ratio) {
1419       best_cp = cp;
1420       best_ratio = tmp_ratio;
1421     }
1422   }
1423 
1424   return sd.region_to_addr(best_cp);
1425 }
1426 
1427 void PSParallelCompact::summarize_spaces_quick()
1428 {
1429   for (unsigned int i = 0; i < last_space_id; ++i) {
1430     const MutableSpace* space = _space_info[i].space();
1431     HeapWord** nta = _space_info[i].new_top_addr();
1432     bool result = _summary_data.summarize(_space_info[i].split_info(),
1433                                           space->bottom(), space->top(), NULL,
1434                                           space->bottom(), space->end(), nta);
1435     assert(result, "space must fit into itself");
1436     _space_info[i].set_dense_prefix(space->bottom());
1437   }
1438 }
1439 
1440 void PSParallelCompact::fill_dense_prefix_end(SpaceId id)
1441 {
1442   HeapWord* const dense_prefix_end = dense_prefix(id);
1443   const RegionData* region = _summary_data.addr_to_region_ptr(dense_prefix_end);
1444   const idx_t dense_prefix_bit = _mark_bitmap.addr_to_bit(dense_prefix_end);
1445   if (dead_space_crosses_boundary(region, dense_prefix_bit)) {
1446     // Only enough dead space is filled so that any remaining dead space to the
1447     // left is larger than the minimum filler object.  (The remainder is filled
1448     // during the copy/update phase.)
1449     //
1450     // The size of the dead space to the right of the boundary is not a
1451     // concern, since compaction will be able to use whatever space is
1452     // available.
1453     //
1454     // Here '||' is the boundary, 'x' represents a don't care bit and a box
1455     // surrounds the space to be filled with an object.
1456     //
1457     // In the 32-bit VM, each bit represents two 32-bit words:
1458     //                              +---+
1459     // a) beg_bits:  ...  x   x   x | 0 | ||   0   x  x  ...
1460     //    end_bits:  ...  x   x   x | 0 | ||   0   x  x  ...
1461     //                              +---+
1462     //
1463     // In the 64-bit VM, each bit represents one 64-bit word:
1464     //                              +------------+
1465     // b) beg_bits:  ...  x   x   x | 0   ||   0 | x  x  ...
1466     //    end_bits:  ...  x   x   1 | 0   ||   0 | x  x  ...
1467     //                              +------------+
1468     //                          +-------+
1469     // c) beg_bits:  ...  x   x | 0   0 | ||   0   x  x  ...
1470     //    end_bits:  ...  x   1 | 0   0 | ||   0   x  x  ...
1471     //                          +-------+
1472     //                      +-----------+
1473     // d) beg_bits:  ...  x | 0   0   0 | ||   0   x  x  ...
1474     //    end_bits:  ...  1 | 0   0   0 | ||   0   x  x  ...
1475     //                      +-----------+
1476     //                          +-------+
1477     // e) beg_bits:  ...  0   0 | 0   0 | ||   0   x  x  ...
1478     //    end_bits:  ...  0   0 | 0   0 | ||   0   x  x  ...
1479     //                          +-------+
1480 
1481     // Initially assume case a, c or e will apply.
1482     size_t obj_len = CollectedHeap::min_fill_size();
1483     HeapWord* obj_beg = dense_prefix_end - obj_len;
1484 
1485 #ifdef  _LP64
1486     if (MinObjAlignment > 1) { // object alignment > heap word size
1487       // Cases a, c or e.
1488     } else if (_mark_bitmap.is_obj_end(dense_prefix_bit - 2)) {
1489       // Case b above.
1490       obj_beg = dense_prefix_end - 1;
1491     } else if (!_mark_bitmap.is_obj_end(dense_prefix_bit - 3) &&
1492                _mark_bitmap.is_obj_end(dense_prefix_bit - 4)) {
1493       // Case d above.
1494       obj_beg = dense_prefix_end - 3;
1495       obj_len = 3;
1496     }
1497 #endif  // #ifdef _LP64
1498 
1499     CollectedHeap::fill_with_object(obj_beg, obj_len);
1500     _mark_bitmap.mark_obj(obj_beg, obj_len);
1501     _summary_data.add_obj(obj_beg, obj_len);
1502     assert(start_array(id) != NULL, "sanity");
1503     start_array(id)->allocate_block(obj_beg);
1504   }
1505 }
1506 
1507 void
1508 PSParallelCompact::summarize_space(SpaceId id, bool maximum_compaction)
1509 {
1510   assert(id < last_space_id, "id out of range");
1511   assert(_space_info[id].dense_prefix() == _space_info[id].space()->bottom(),
1512          "should have been reset in summarize_spaces_quick()");
1513 
1514   const MutableSpace* space = _space_info[id].space();
1515   if (_space_info[id].new_top() != space->bottom()) {
1516     HeapWord* dense_prefix_end = compute_dense_prefix(id, maximum_compaction);
1517     _space_info[id].set_dense_prefix(dense_prefix_end);
1518 
1519 #ifndef PRODUCT
1520     if (TraceParallelOldGCDensePrefix) {
1521       print_dense_prefix_stats("ratio", id, maximum_compaction,
1522                                dense_prefix_end);
1523       HeapWord* addr = compute_dense_prefix_via_density(id, maximum_compaction);
1524       print_dense_prefix_stats("density", id, maximum_compaction, addr);
1525     }
1526 #endif  // #ifndef PRODUCT
1527 
1528     // Recompute the summary data, taking into account the dense prefix.  If
1529     // every last byte will be reclaimed, then the existing summary data which
1530     // compacts everything can be left in place.
1531     if (!maximum_compaction && dense_prefix_end != space->bottom()) {
1532       // If dead space crosses the dense prefix boundary, it is (at least
1533       // partially) filled with a dummy object, marked live and added to the
1534       // summary data.  This simplifies the copy/update phase and must be done
1535       // before the final locations of objects are determined, to prevent
1536       // leaving a fragment of dead space that is too small to fill.
1537       fill_dense_prefix_end(id);
1538 
1539       // Compute the destination of each Region, and thus each object.
1540       _summary_data.summarize_dense_prefix(space->bottom(), dense_prefix_end);
1541       _summary_data.summarize(_space_info[id].split_info(),
1542                               dense_prefix_end, space->top(), NULL,
1543                               dense_prefix_end, space->end(),
1544                               _space_info[id].new_top_addr());
1545     }
1546   }
1547 
1548   if (log_develop_is_enabled(Trace, gc, compaction)) {
1549     const size_t region_size = ParallelCompactData::RegionSize;
1550     HeapWord* const dense_prefix_end = _space_info[id].dense_prefix();
1551     const size_t dp_region = _summary_data.addr_to_region_idx(dense_prefix_end);
1552     const size_t dp_words = pointer_delta(dense_prefix_end, space->bottom());
1553     HeapWord* const new_top = _space_info[id].new_top();
1554     const HeapWord* nt_aligned_up = _summary_data.region_align_up(new_top);
1555     const size_t cr_words = pointer_delta(nt_aligned_up, dense_prefix_end);
1556     log_develop_trace(gc, compaction)(
1557         "id=%d cap=" SIZE_FORMAT " dp=" PTR_FORMAT " "
1558         "dp_region=" SIZE_FORMAT " " "dp_count=" SIZE_FORMAT " "
1559         "cr_count=" SIZE_FORMAT " " "nt=" PTR_FORMAT,
1560         id, space->capacity_in_words(), p2i(dense_prefix_end),
1561         dp_region, dp_words / region_size,
1562         cr_words / region_size, p2i(new_top));
1563   }
1564 }
1565 
1566 #ifndef PRODUCT
1567 void PSParallelCompact::summary_phase_msg(SpaceId dst_space_id,
1568                                           HeapWord* dst_beg, HeapWord* dst_end,
1569                                           SpaceId src_space_id,
1570                                           HeapWord* src_beg, HeapWord* src_end)
1571 {
1572   log_develop_trace(gc, compaction)(
1573       "Summarizing %d [%s] into %d [%s]:  "
1574       "src=" PTR_FORMAT "-" PTR_FORMAT " "
1575       SIZE_FORMAT "-" SIZE_FORMAT " "
1576       "dst=" PTR_FORMAT "-" PTR_FORMAT " "
1577       SIZE_FORMAT "-" SIZE_FORMAT,
1578       src_space_id, space_names[src_space_id],
1579       dst_space_id, space_names[dst_space_id],
1580       p2i(src_beg), p2i(src_end),
1581       _summary_data.addr_to_region_idx(src_beg),
1582       _summary_data.addr_to_region_idx(src_end),
1583       p2i(dst_beg), p2i(dst_end),
1584       _summary_data.addr_to_region_idx(dst_beg),
1585       _summary_data.addr_to_region_idx(dst_end));
1586 }
1587 #endif  // #ifndef PRODUCT
1588 
1589 void PSParallelCompact::summary_phase(ParCompactionManager* cm,
1590                                       bool maximum_compaction)
1591 {
1592   GCTraceTime(Info, gc, phases) tm("Summary Phase", &_gc_timer);
1593 
1594 #ifdef  ASSERT
1595   if (TraceParallelOldGCMarkingPhase) {
1596     tty->print_cr("add_obj_count=" SIZE_FORMAT " "
1597                   "add_obj_bytes=" SIZE_FORMAT,
1598                   add_obj_count, add_obj_size * HeapWordSize);
1599     tty->print_cr("mark_bitmap_count=" SIZE_FORMAT " "
1600                   "mark_bitmap_bytes=" SIZE_FORMAT,
1601                   mark_bitmap_count, mark_bitmap_size * HeapWordSize);
1602   }
1603 #endif  // #ifdef ASSERT
1604 
1605   // Quick summarization of each space into itself, to see how much is live.
1606   summarize_spaces_quick();
1607 
1608   log_develop_trace(gc, compaction)("summary phase:  after summarizing each space to self");
1609   NOT_PRODUCT(print_region_ranges());
1610   NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info));
1611 
1612   // The amount of live data that will end up in old space (assuming it fits).
1613   size_t old_space_total_live = 0;
1614   for (unsigned int id = old_space_id; id < last_space_id; ++id) {
1615     old_space_total_live += pointer_delta(_space_info[id].new_top(),
1616                                           _space_info[id].space()->bottom());
1617   }
1618 
1619   MutableSpace* const old_space = _space_info[old_space_id].space();
1620   const size_t old_capacity = old_space->capacity_in_words();
1621   if (old_space_total_live > old_capacity) {
1622     // XXX - should also try to expand
1623     maximum_compaction = true;
1624   }
1625 
1626   // Old generations.
1627   summarize_space(old_space_id, maximum_compaction);
1628 
1629   // Summarize the remaining spaces in the young gen.  The initial target space
1630   // is the old gen.  If a space does not fit entirely into the target, then the
1631   // remainder is compacted into the space itself and that space becomes the new
1632   // target.
1633   SpaceId dst_space_id = old_space_id;
1634   HeapWord* dst_space_end = old_space->end();
1635   HeapWord** new_top_addr = _space_info[dst_space_id].new_top_addr();
1636   for (unsigned int id = eden_space_id; id < last_space_id; ++id) {
1637     const MutableSpace* space = _space_info[id].space();
1638     const size_t live = pointer_delta(_space_info[id].new_top(),
1639                                       space->bottom());
1640     const size_t available = pointer_delta(dst_space_end, *new_top_addr);
1641 
1642     NOT_PRODUCT(summary_phase_msg(dst_space_id, *new_top_addr, dst_space_end,
1643                                   SpaceId(id), space->bottom(), space->top());)
1644     if (live > 0 && live <= available) {
1645       // All the live data will fit.
1646       bool done = _summary_data.summarize(_space_info[id].split_info(),
1647                                           space->bottom(), space->top(),
1648                                           NULL,
1649                                           *new_top_addr, dst_space_end,
1650                                           new_top_addr);
1651       assert(done, "space must fit into old gen");
1652 
1653       // Reset the new_top value for the space.
1654       _space_info[id].set_new_top(space->bottom());
1655     } else if (live > 0) {
1656       // Attempt to fit part of the source space into the target space.
1657       HeapWord* next_src_addr = NULL;
1658       bool done = _summary_data.summarize(_space_info[id].split_info(),
1659                                           space->bottom(), space->top(),
1660                                           &next_src_addr,
1661                                           *new_top_addr, dst_space_end,
1662                                           new_top_addr);
1663       assert(!done, "space should not fit into old gen");
1664       assert(next_src_addr != NULL, "sanity");
1665 
1666       // The source space becomes the new target, so the remainder is compacted
1667       // within the space itself.
1668       dst_space_id = SpaceId(id);
1669       dst_space_end = space->end();
1670       new_top_addr = _space_info[id].new_top_addr();
1671       NOT_PRODUCT(summary_phase_msg(dst_space_id,
1672                                     space->bottom(), dst_space_end,
1673                                     SpaceId(id), next_src_addr, space->top());)
1674       done = _summary_data.summarize(_space_info[id].split_info(),
1675                                      next_src_addr, space->top(),
1676                                      NULL,
1677                                      space->bottom(), dst_space_end,
1678                                      new_top_addr);
1679       assert(done, "space must fit when compacted into itself");
1680       assert(*new_top_addr <= space->top(), "usage should not grow");
1681     }
1682   }
1683 
1684   log_develop_trace(gc, compaction)("Summary_phase:  after final summarization");
1685   NOT_PRODUCT(print_region_ranges());
1686   NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info));
1687 }
1688 
1689 // This method should contain all heap-specific policy for invoking a full
1690 // collection.  invoke_no_policy() will only attempt to compact the heap; it
1691 // will do nothing further.  If we need to bail out for policy reasons, scavenge
1692 // before full gc, or any other specialized behavior, it needs to be added here.
1693 //
1694 // Note that this method should only be called from the vm_thread while at a
1695 // safepoint.
1696 //
1697 // Note that the all_soft_refs_clear flag in the collector policy
1698 // may be true because this method can be called without intervening
1699 // activity.  For example when the heap space is tight and full measure
1700 // are being taken to free space.
1701 void PSParallelCompact::invoke(bool maximum_heap_compaction) {
1702   assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
1703   assert(Thread::current() == (Thread*)VMThread::vm_thread(),
1704          "should be in vm thread");
1705 
1706   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
1707   GCCause::Cause gc_cause = heap->gc_cause();
1708   assert(!heap->is_gc_active(), "not reentrant");
1709 
1710   PSAdaptiveSizePolicy* policy = heap->size_policy();
1711   IsGCActiveMark mark;
1712 
1713   if (ScavengeBeforeFullGC) {
1714     PSScavenge::invoke_no_policy();
1715   }
1716 
1717   const bool clear_all_soft_refs =
1718     heap->collector_policy()->should_clear_all_soft_refs();
1719 
1720   PSParallelCompact::invoke_no_policy(clear_all_soft_refs ||
1721                                       maximum_heap_compaction);
1722 }
1723 
1724 // This method contains no policy. You should probably
1725 // be calling invoke() instead.
1726 bool PSParallelCompact::invoke_no_policy(bool maximum_heap_compaction) {
1727   assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
1728   assert(ref_processor() != NULL, "Sanity");
1729 
1730   if (GCLocker::check_active_before_gc()) {
1731     return false;
1732   }
1733 
1734   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
1735 
1736   GCIdMark gc_id_mark;
1737   _gc_timer.register_gc_start();
1738   _gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start());
1739 
1740   TimeStamp marking_start;
1741   TimeStamp compaction_start;
1742   TimeStamp collection_exit;
1743 
1744   GCCause::Cause gc_cause = heap->gc_cause();
1745   PSYoungGen* young_gen = heap->young_gen();
1746   PSOldGen* old_gen = heap->old_gen();
1747   PSAdaptiveSizePolicy* size_policy = heap->size_policy();
1748 
1749   // The scope of casr should end after code that can change
1750   // CollectorPolicy::_should_clear_all_soft_refs.
1751   ClearedAllSoftRefs casr(maximum_heap_compaction,
1752                           heap->collector_policy());
1753 
1754   if (ZapUnusedHeapArea) {
1755     // Save information needed to minimize mangling
1756     heap->record_gen_tops_before_GC();
1757   }
1758 
1759   // Make sure data structures are sane, make the heap parsable, and do other
1760   // miscellaneous bookkeeping.
1761   pre_compact();
1762 
1763   PreGCValues pre_gc_values(heap);
1764 
1765   // Get the compaction manager reserved for the VM thread.
1766   ParCompactionManager* const vmthread_cm =
1767     ParCompactionManager::manager_array(gc_task_manager()->workers());
1768 
1769   {
1770     ResourceMark rm;
1771     HandleMark hm;
1772 
1773     // Set the number of GC threads to be used in this collection
1774     gc_task_manager()->set_active_gang();
1775     gc_task_manager()->task_idle_workers();
1776 
1777     GCTraceCPUTime tcpu;
1778     GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause, true);
1779 
1780     heap->pre_full_gc_dump(&_gc_timer);
1781 
1782     TraceCollectorStats tcs(counters());
1783     TraceMemoryManagerStats tms(true /* Full GC */,gc_cause);
1784 
1785     if (TraceOldGenTime) accumulated_time()->start();
1786 
1787     // Let the size policy know we're starting
1788     size_policy->major_collection_begin();
1789 
1790     CodeCache::gc_prologue();
1791 
1792 #if defined(COMPILER2) || INCLUDE_JVMCI
1793     DerivedPointerTable::clear();
1794 #endif
1795 
1796     ref_processor()->enable_discovery();
1797     ref_processor()->setup_policy(maximum_heap_compaction);
1798 
1799     bool marked_for_unloading = false;
1800 
1801     marking_start.update();
1802     marking_phase(vmthread_cm, maximum_heap_compaction, &_gc_tracer);
1803 
1804     bool max_on_system_gc = UseMaximumCompactionOnSystemGC
1805       && GCCause::is_user_requested_gc(gc_cause);
1806     summary_phase(vmthread_cm, maximum_heap_compaction || max_on_system_gc);
1807 
1808 #if defined(COMPILER2) || INCLUDE_JVMCI
1809     assert(DerivedPointerTable::is_active(), "Sanity");
1810     DerivedPointerTable::set_active(false);
1811 #endif
1812 
1813     // adjust_roots() updates Universe::_intArrayKlassObj which is
1814     // needed by the compaction for filling holes in the dense prefix.
1815     adjust_roots(vmthread_cm);
1816 
1817     compaction_start.update();
1818     compact();
1819 
1820     // Reset the mark bitmap, summary data, and do other bookkeeping.  Must be
1821     // done before resizing.
1822     post_compact();
1823 
1824     // Let the size policy know we're done
1825     size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause);
1826 
1827     if (UseAdaptiveSizePolicy) {
1828       log_debug(gc, ergo)("AdaptiveSizeStart: collection: %d ", heap->total_collections());
1829       log_trace(gc, ergo)("old_gen_capacity: " SIZE_FORMAT " young_gen_capacity: " SIZE_FORMAT,
1830                           old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes());
1831 
1832       // Don't check if the size_policy is ready here.  Let
1833       // the size_policy check that internally.
1834       if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&
1835           AdaptiveSizePolicy::should_update_promo_stats(gc_cause)) {
1836         // Swap the survivor spaces if from_space is empty. The
1837         // resize_young_gen() called below is normally used after
1838         // a successful young GC and swapping of survivor spaces;
1839         // otherwise, it will fail to resize the young gen with
1840         // the current implementation.
1841         if (young_gen->from_space()->is_empty()) {
1842           young_gen->from_space()->clear(SpaceDecorator::Mangle);
1843           young_gen->swap_spaces();
1844         }
1845 
1846         // Calculate optimal free space amounts
1847         assert(young_gen->max_size() >
1848           young_gen->from_space()->capacity_in_bytes() +
1849           young_gen->to_space()->capacity_in_bytes(),
1850           "Sizes of space in young gen are out-of-bounds");
1851 
1852         size_t young_live = young_gen->used_in_bytes();
1853         size_t eden_live = young_gen->eden_space()->used_in_bytes();
1854         size_t old_live = old_gen->used_in_bytes();
1855         size_t cur_eden = young_gen->eden_space()->capacity_in_bytes();
1856         size_t max_old_gen_size = old_gen->max_gen_size();
1857         size_t max_eden_size = young_gen->max_size() -
1858           young_gen->from_space()->capacity_in_bytes() -
1859           young_gen->to_space()->capacity_in_bytes();
1860 
1861         // Used for diagnostics
1862         size_policy->clear_generation_free_space_flags();
1863 
1864         size_policy->compute_generations_free_space(young_live,
1865                                                     eden_live,
1866                                                     old_live,
1867                                                     cur_eden,
1868                                                     max_old_gen_size,
1869                                                     max_eden_size,
1870                                                     true /* full gc*/);
1871 
1872         size_policy->check_gc_overhead_limit(young_live,
1873                                              eden_live,
1874                                              max_old_gen_size,
1875                                              max_eden_size,
1876                                              true /* full gc*/,
1877                                              gc_cause,
1878                                              heap->collector_policy());
1879 
1880         size_policy->decay_supplemental_growth(true /* full gc*/);
1881 
1882         heap->resize_old_gen(
1883           size_policy->calculated_old_free_size_in_bytes());
1884 
1885         heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(),
1886                                size_policy->calculated_survivor_size_in_bytes());
1887       }
1888 
1889       log_debug(gc, ergo)("AdaptiveSizeStop: collection: %d ", heap->total_collections());
1890     }
1891 
1892     if (UsePerfData) {
1893       PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters();
1894       counters->update_counters();
1895       counters->update_old_capacity(old_gen->capacity_in_bytes());
1896       counters->update_young_capacity(young_gen->capacity_in_bytes());
1897     }
1898 
1899     heap->resize_all_tlabs();
1900 
1901     // Resize the metaspace capacity after a collection
1902     MetaspaceGC::compute_new_size();
1903 
1904     if (TraceOldGenTime) {
1905       accumulated_time()->stop();
1906     }
1907 
1908     young_gen->print_used_change(pre_gc_values.young_gen_used());
1909     old_gen->print_used_change(pre_gc_values.old_gen_used());
1910     MetaspaceAux::print_metaspace_change(pre_gc_values.metadata_used());
1911 
1912     // Track memory usage and detect low memory
1913     MemoryService::track_memory_usage();
1914     heap->update_counters();
1915     gc_task_manager()->release_idle_workers();
1916 
1917     heap->post_full_gc_dump(&_gc_timer);
1918   }
1919 
1920 #ifdef ASSERT
1921   for (size_t i = 0; i < ParallelGCThreads + 1; ++i) {
1922     ParCompactionManager* const cm =
1923       ParCompactionManager::manager_array(int(i));
1924     assert(cm->marking_stack()->is_empty(),       "should be empty");
1925     assert(cm->region_stack()->is_empty(), "Region stack " SIZE_FORMAT " is not empty", i);
1926   }
1927 #endif // ASSERT
1928 
1929   if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
1930     HandleMark hm;  // Discard invalid handles created during verification
1931     Universe::verify("After GC");
1932   }
1933 
1934   // Re-verify object start arrays
1935   if (VerifyObjectStartArray &&
1936       VerifyAfterGC) {
1937     old_gen->verify_object_start_array();
1938   }
1939 
1940   if (ZapUnusedHeapArea) {
1941     old_gen->object_space()->check_mangled_unused_area_complete();
1942   }
1943 
1944   NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
1945 
1946   collection_exit.update();
1947 
1948   heap->print_heap_after_gc();
1949   heap->trace_heap_after_gc(&_gc_tracer);
1950 
1951   log_debug(gc, task, time)("VM-Thread " JLONG_FORMAT " " JLONG_FORMAT " " JLONG_FORMAT,
1952                          marking_start.ticks(), compaction_start.ticks(),
1953                          collection_exit.ticks());
1954   gc_task_manager()->print_task_time_stamps();
1955 
1956 #ifdef TRACESPINNING
1957   ParallelTaskTerminator::print_termination_counts();
1958 #endif
1959 
1960   AdaptiveSizePolicyOutput::print(size_policy, heap->total_collections());
1961 
1962   _gc_timer.register_gc_end();
1963 
1964   _gc_tracer.report_dense_prefix(dense_prefix(old_space_id));
1965   _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions());
1966 
1967   return true;
1968 }
1969 
1970 bool PSParallelCompact::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
1971                                              PSYoungGen* young_gen,
1972                                              PSOldGen* old_gen) {
1973   MutableSpace* const eden_space = young_gen->eden_space();
1974   assert(!eden_space->is_empty(), "eden must be non-empty");
1975   assert(young_gen->virtual_space()->alignment() ==
1976          old_gen->virtual_space()->alignment(), "alignments do not match");
1977 
1978   if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) {
1979     return false;
1980   }
1981 
1982   // Both generations must be completely committed.
1983   if (young_gen->virtual_space()->uncommitted_size() != 0) {
1984     return false;
1985   }
1986   if (old_gen->virtual_space()->uncommitted_size() != 0) {
1987     return false;
1988   }
1989 
1990   // Figure out how much to take from eden.  Include the average amount promoted
1991   // in the total; otherwise the next young gen GC will simply bail out to a
1992   // full GC.
1993   const size_t alignment = old_gen->virtual_space()->alignment();
1994   const size_t eden_used = eden_space->used_in_bytes();
1995   const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average();
1996   const size_t absorb_size = align_size_up(eden_used + promoted, alignment);
1997   const size_t eden_capacity = eden_space->capacity_in_bytes();
1998 
1999   if (absorb_size >= eden_capacity) {
2000     return false; // Must leave some space in eden.
2001   }
2002 
2003   const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size;
2004   if (new_young_size < young_gen->min_gen_size()) {
2005     return false; // Respect young gen minimum size.
2006   }
2007 
2008   log_trace(heap, ergo)(" absorbing " SIZE_FORMAT "K:  "
2009                         "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K "
2010                         "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K "
2011                         "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ",
2012                         absorb_size / K,
2013                         eden_capacity / K, (eden_capacity - absorb_size) / K,
2014                         young_gen->from_space()->used_in_bytes() / K,
2015                         young_gen->to_space()->used_in_bytes() / K,
2016                         young_gen->capacity_in_bytes() / K, new_young_size / K);
2017 
2018   // Fill the unused part of the old gen.
2019   MutableSpace* const old_space = old_gen->object_space();
2020   HeapWord* const unused_start = old_space->top();
2021   size_t const unused_words = pointer_delta(old_space->end(), unused_start);
2022 
2023   if (unused_words > 0) {
2024     if (unused_words < CollectedHeap::min_fill_size()) {
2025       return false;  // If the old gen cannot be filled, must give up.
2026     }
2027     CollectedHeap::fill_with_objects(unused_start, unused_words);
2028   }
2029 
2030   // Take the live data from eden and set both top and end in the old gen to
2031   // eden top.  (Need to set end because reset_after_change() mangles the region
2032   // from end to virtual_space->high() in debug builds).
2033   HeapWord* const new_top = eden_space->top();
2034   old_gen->virtual_space()->expand_into(young_gen->virtual_space(),
2035                                         absorb_size);
2036   young_gen->reset_after_change();
2037   old_space->set_top(new_top);
2038   old_space->set_end(new_top);
2039   old_gen->reset_after_change();
2040 
2041   // Update the object start array for the filler object and the data from eden.
2042   ObjectStartArray* const start_array = old_gen->start_array();
2043   for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) {
2044     start_array->allocate_block(p);
2045   }
2046 
2047   // Could update the promoted average here, but it is not typically updated at
2048   // full GCs and the value to use is unclear.  Something like
2049   //
2050   // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc.
2051 
2052   size_policy->set_bytes_absorbed_from_eden(absorb_size);
2053   return true;
2054 }
2055 
2056 GCTaskManager* const PSParallelCompact::gc_task_manager() {
2057   assert(ParallelScavengeHeap::gc_task_manager() != NULL,
2058     "shouldn't return NULL");
2059   return ParallelScavengeHeap::gc_task_manager();
2060 }
2061 
2062 class CreateThreadRootsMarkingTasksClosure : public ThreadClosure {
2063 
2064 private:
2065   GCTaskQueue* _queue;
2066 
2067 public:
2068 
2069   CreateThreadRootsMarkingTasksClosure(GCTaskQueue* q) : _queue(q) {
2070   }
2071 
2072   void do_thread(Thread* thread) {
2073     if (thread->is_Java_thread()) {
2074       _queue->enqueue(new ThreadRootsMarkingTask((JavaThread*) thread));
2075     } else if (thread->is_VM_thread()) {
2076       _queue->enqueue(new ThreadRootsMarkingTask((VMThread*) thread));
2077     }
2078   }
2079 
2080 };
2081 
2082 void PSParallelCompact::marking_phase(ParCompactionManager* cm,
2083                                       bool maximum_heap_compaction,
2084                                       ParallelOldTracer *gc_tracer) {
2085   // Recursively traverse all live objects and mark them
2086   GCTraceTime(Info, gc, phases) tm("Marking Phase", &_gc_timer);
2087 
2088   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
2089   uint parallel_gc_threads = heap->gc_task_manager()->workers();
2090   uint active_gc_threads = heap->gc_task_manager()->active_workers();
2091   TaskQueueSetSuper* qset = ParCompactionManager::stack_array();
2092   ParallelTaskTerminator terminator(active_gc_threads, qset);
2093 
2094   ParCompactionManager::MarkAndPushClosure mark_and_push_closure(cm);
2095   ParCompactionManager::FollowStackClosure follow_stack_closure(cm);
2096 
2097   // Need new claim bits before marking starts.
2098   ClassLoaderDataGraph::clear_claimed_marks();
2099 
2100   {
2101     GCTraceTime(Debug, gc, phases) tm("Par Mark", &_gc_timer);
2102 
2103     ParallelScavengeHeap::ParStrongRootsScope psrs;
2104 
2105     GCTaskQueue* q = GCTaskQueue::create();
2106 
2107     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::universe));
2108     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jni_handles));
2109     // We scan the thread roots in parallel
2110     CreateThreadRootsMarkingTasksClosure cl(q);
2111     Threads::threads_do(&cl);
2112     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::object_synchronizer));
2113     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::flat_profiler));
2114     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::management));
2115     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::system_dictionary));
2116     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::class_loader_data));
2117     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jvmti));
2118     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::code_cache));
2119 
2120     if (active_gc_threads > 1) {
2121       for (uint j = 0; j < active_gc_threads; j++) {
2122         q->enqueue(new StealMarkingTask(&terminator));
2123       }
2124     }
2125 
2126     gc_task_manager()->execute_and_wait(q);
2127   }
2128 
2129   // Process reference objects found during marking
2130   {
2131     GCTraceTime(Debug, gc, phases) tm("Reference Processing", &_gc_timer);
2132 
2133     ReferenceProcessorStats stats;
2134     if (ref_processor()->processing_is_mt()) {
2135       RefProcTaskExecutor task_executor;
2136       stats = ref_processor()->process_discovered_references(
2137         is_alive_closure(), &mark_and_push_closure, &follow_stack_closure,
2138         &task_executor, &_gc_timer);
2139     } else {
2140       stats = ref_processor()->process_discovered_references(
2141         is_alive_closure(), &mark_and_push_closure, &follow_stack_closure, NULL,
2142         &_gc_timer);
2143     }
2144 
2145     gc_tracer->report_gc_reference_stats(stats);
2146   }
2147 
2148   // This is the point where the entire marking should have completed.
2149   assert(cm->marking_stacks_empty(), "Marking should have completed");
2150 
2151   {
2152     GCTraceTime(Debug, gc, phases) tm_m("Class Unloading", &_gc_timer);
2153 
2154     // Follow system dictionary roots and unload classes.
2155     bool purged_class = SystemDictionary::do_unloading(is_alive_closure());
2156 
2157     // Unload nmethods.
2158     CodeCache::do_unloading(is_alive_closure(), purged_class);
2159 
2160     // Prune dead klasses from subklass/sibling/implementor lists.
2161     Klass::clean_weak_klass_links(is_alive_closure());
2162   }
2163 
2164   {
2165     GCTraceTime(Debug, gc, phases) t("Scrub String Table", &_gc_timer);
2166     // Delete entries for dead interned strings.
2167     StringTable::unlink(is_alive_closure());
2168   }
2169 
2170   {
2171     GCTraceTime(Debug, gc, phases) t("Scrub Symbol Table", &_gc_timer);
2172     // Clean up unreferenced symbols in symbol table.
2173     SymbolTable::unlink();
2174   }
2175 
2176   _gc_tracer.report_object_count_after_gc(is_alive_closure());
2177 }
2178 
2179 void PSParallelCompact::adjust_roots(ParCompactionManager* cm) {
2180   // Adjust the pointers to reflect the new locations
2181   GCTraceTime(Info, gc, phases) tm("Adjust Roots", &_gc_timer);
2182 
2183   // Need new claim bits when tracing through and adjusting pointers.
2184   ClassLoaderDataGraph::clear_claimed_marks();
2185 
2186   PSParallelCompact::AdjustPointerClosure oop_closure(cm);
2187   PSParallelCompact::AdjustKlassClosure klass_closure(cm);
2188 
2189   // General strong roots.
2190   Universe::oops_do(&oop_closure);
2191   JNIHandles::oops_do(&oop_closure);   // Global (strong) JNI handles
2192   Threads::oops_do(&oop_closure, NULL);
2193   ObjectSynchronizer::oops_do(&oop_closure);
2194   FlatProfiler::oops_do(&oop_closure);
2195   Management::oops_do(&oop_closure);
2196   JvmtiExport::oops_do(&oop_closure);
2197   SystemDictionary::oops_do(&oop_closure);
2198   ClassLoaderDataGraph::oops_do(&oop_closure, &klass_closure, true);
2199 
2200   // Now adjust pointers in remaining weak roots.  (All of which should
2201   // have been cleared if they pointed to non-surviving objects.)
2202   // Global (weak) JNI handles
2203   JNIHandles::weak_oops_do(&oop_closure);
2204 
2205   CodeBlobToOopClosure adjust_from_blobs(&oop_closure, CodeBlobToOopClosure::FixRelocations);
2206   CodeCache::blobs_do(&adjust_from_blobs);
2207   StringTable::oops_do(&oop_closure);
2208   ref_processor()->weak_oops_do(&oop_closure);
2209   // Roots were visited so references into the young gen in roots
2210   // may have been scanned.  Process them also.
2211   // Should the reference processor have a span that excludes
2212   // young gen objects?
2213   PSScavenge::reference_processor()->weak_oops_do(&oop_closure);
2214 }
2215 
2216 // Helper class to print 8 region numbers per line and then print the total at the end.
2217 class FillableRegionLogger : public StackObj {
2218 private:
2219   Log(gc, compaction) log;
2220   static const int LineLength = 8;
2221   size_t _regions[LineLength];
2222   int _next_index;
2223   bool _enabled;
2224   size_t _total_regions;
2225 public:
2226   FillableRegionLogger() : _next_index(0), _total_regions(0), _enabled(log_develop_is_enabled(Trace, gc, compaction)) { }
2227   ~FillableRegionLogger() {
2228     log.trace(SIZE_FORMAT " initially fillable regions", _total_regions);
2229   }
2230 
2231   void print_line() {
2232     if (!_enabled || _next_index == 0) {
2233       return;
2234     }
2235     FormatBuffer<> line("Fillable: ");
2236     for (int i = 0; i < _next_index; i++) {
2237       line.append(" " SIZE_FORMAT_W(7), _regions[i]);
2238     }
2239     log.trace("%s", line.buffer());
2240     _next_index = 0;
2241   }
2242 
2243   void handle(size_t region) {
2244     if (!_enabled) {
2245       return;
2246     }
2247     _regions[_next_index++] = region;
2248     if (_next_index == LineLength) {
2249       print_line();
2250     }
2251     _total_regions++;
2252   }
2253 };
2254 
2255 void PSParallelCompact::prepare_region_draining_tasks(GCTaskQueue* q,
2256                                                       uint parallel_gc_threads)
2257 {
2258   GCTraceTime(Trace, gc, phases) tm("Drain Task Setup", &_gc_timer);
2259 
2260   // Find the threads that are active
2261   unsigned int which = 0;
2262 
2263   // Find all regions that are available (can be filled immediately) and
2264   // distribute them to the thread stacks.  The iteration is done in reverse
2265   // order (high to low) so the regions will be removed in ascending order.
2266 
2267   const ParallelCompactData& sd = PSParallelCompact::summary_data();
2268 
2269   which = 0;
2270   // id + 1 is used to test termination so unsigned  can
2271   // be used with an old_space_id == 0.
2272   FillableRegionLogger region_logger;
2273   for (unsigned int id = to_space_id; id + 1 > old_space_id; --id) {
2274     SpaceInfo* const space_info = _space_info + id;
2275     MutableSpace* const space = space_info->space();
2276     HeapWord* const new_top = space_info->new_top();
2277 
2278     const size_t beg_region = sd.addr_to_region_idx(space_info->dense_prefix());
2279     const size_t end_region =
2280       sd.addr_to_region_idx(sd.region_align_up(new_top));
2281 
2282     for (size_t cur = end_region - 1; cur + 1 > beg_region; --cur) {
2283       if (sd.region(cur)->claim_unsafe()) {
2284         ParCompactionManager* cm = ParCompactionManager::manager_array(which);
2285         cm->region_stack()->push(cur);
2286         region_logger.handle(cur);
2287         // Assign regions to tasks in round-robin fashion.
2288         if (++which == parallel_gc_threads) {
2289           which = 0;
2290         }
2291       }
2292     }
2293     region_logger.print_line();
2294   }
2295 }
2296 
2297 #define PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING 4
2298 
2299 void PSParallelCompact::enqueue_dense_prefix_tasks(GCTaskQueue* q,
2300                                                     uint parallel_gc_threads) {
2301   GCTraceTime(Trace, gc, phases) tm("Dense Prefix Task Setup", &_gc_timer);
2302 
2303   ParallelCompactData& sd = PSParallelCompact::summary_data();
2304 
2305   // Iterate over all the spaces adding tasks for updating
2306   // regions in the dense prefix.  Assume that 1 gc thread
2307   // will work on opening the gaps and the remaining gc threads
2308   // will work on the dense prefix.
2309   unsigned int space_id;
2310   for (space_id = old_space_id; space_id < last_space_id; ++ space_id) {
2311     HeapWord* const dense_prefix_end = _space_info[space_id].dense_prefix();
2312     const MutableSpace* const space = _space_info[space_id].space();
2313 
2314     if (dense_prefix_end == space->bottom()) {
2315       // There is no dense prefix for this space.
2316       continue;
2317     }
2318 
2319     // The dense prefix is before this region.
2320     size_t region_index_end_dense_prefix =
2321         sd.addr_to_region_idx(dense_prefix_end);
2322     RegionData* const dense_prefix_cp =
2323       sd.region(region_index_end_dense_prefix);
2324     assert(dense_prefix_end == space->end() ||
2325            dense_prefix_cp->available() ||
2326            dense_prefix_cp->claimed(),
2327            "The region after the dense prefix should always be ready to fill");
2328 
2329     size_t region_index_start = sd.addr_to_region_idx(space->bottom());
2330 
2331     // Is there dense prefix work?
2332     size_t total_dense_prefix_regions =
2333       region_index_end_dense_prefix - region_index_start;
2334     // How many regions of the dense prefix should be given to
2335     // each thread?
2336     if (total_dense_prefix_regions > 0) {
2337       uint tasks_for_dense_prefix = 1;
2338       if (total_dense_prefix_regions <=
2339           (parallel_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING)) {
2340         // Don't over partition.  This assumes that
2341         // PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING is a small integer value
2342         // so there are not many regions to process.
2343         tasks_for_dense_prefix = parallel_gc_threads;
2344       } else {
2345         // Over partition
2346         tasks_for_dense_prefix = parallel_gc_threads *
2347           PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING;
2348       }
2349       size_t regions_per_thread = total_dense_prefix_regions /
2350         tasks_for_dense_prefix;
2351       // Give each thread at least 1 region.
2352       if (regions_per_thread == 0) {
2353         regions_per_thread = 1;
2354       }
2355 
2356       for (uint k = 0; k < tasks_for_dense_prefix; k++) {
2357         if (region_index_start >= region_index_end_dense_prefix) {
2358           break;
2359         }
2360         // region_index_end is not processed
2361         size_t region_index_end = MIN2(region_index_start + regions_per_thread,
2362                                        region_index_end_dense_prefix);
2363         q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id),
2364                                              region_index_start,
2365                                              region_index_end));
2366         region_index_start = region_index_end;
2367       }
2368     }
2369     // This gets any part of the dense prefix that did not
2370     // fit evenly.
2371     if (region_index_start < region_index_end_dense_prefix) {
2372       q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id),
2373                                            region_index_start,
2374                                            region_index_end_dense_prefix));
2375     }
2376   }
2377 }
2378 
2379 void PSParallelCompact::enqueue_region_stealing_tasks(
2380                                      GCTaskQueue* q,
2381                                      ParallelTaskTerminator* terminator_ptr,
2382                                      uint parallel_gc_threads) {
2383   GCTraceTime(Trace, gc, phases) tm("Steal Task Setup", &_gc_timer);
2384 
2385   // Once a thread has drained it's stack, it should try to steal regions from
2386   // other threads.
2387   for (uint j = 0; j < parallel_gc_threads; j++) {
2388     q->enqueue(new CompactionWithStealingTask(terminator_ptr));
2389   }
2390 }
2391 
2392 #ifdef ASSERT
2393 // Write a histogram of the number of times the block table was filled for a
2394 // region.
2395 void PSParallelCompact::write_block_fill_histogram()
2396 {
2397   if (!log_develop_is_enabled(Trace, gc, compaction)) {
2398     return;
2399   }
2400 
2401   Log(gc, compaction) log;
2402   ResourceMark rm;
2403   outputStream* out = log.trace_stream();
2404 
2405   typedef ParallelCompactData::RegionData rd_t;
2406   ParallelCompactData& sd = summary_data();
2407 
2408   for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2409     MutableSpace* const spc = _space_info[id].space();
2410     if (spc->bottom() != spc->top()) {
2411       const rd_t* const beg = sd.addr_to_region_ptr(spc->bottom());
2412       HeapWord* const top_aligned_up = sd.region_align_up(spc->top());
2413       const rd_t* const end = sd.addr_to_region_ptr(top_aligned_up);
2414 
2415       size_t histo[5] = { 0, 0, 0, 0, 0 };
2416       const size_t histo_len = sizeof(histo) / sizeof(size_t);
2417       const size_t region_cnt = pointer_delta(end, beg, sizeof(rd_t));
2418 
2419       for (const rd_t* cur = beg; cur < end; ++cur) {
2420         ++histo[MIN2(cur->blocks_filled_count(), histo_len - 1)];
2421       }
2422       out->print("Block fill histogram: %u %-4s" SIZE_FORMAT_W(5), id, space_names[id], region_cnt);
2423       for (size_t i = 0; i < histo_len; ++i) {
2424         out->print(" " SIZE_FORMAT_W(5) " %5.1f%%",
2425                    histo[i], 100.0 * histo[i] / region_cnt);
2426       }
2427       out->cr();
2428     }
2429   }
2430 }
2431 #endif // #ifdef ASSERT
2432 
2433 void PSParallelCompact::compact() {
2434   GCTraceTime(Info, gc, phases) tm("Compaction Phase", &_gc_timer);
2435 
2436   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
2437   PSOldGen* old_gen = heap->old_gen();
2438   old_gen->start_array()->reset();
2439   uint parallel_gc_threads = heap->gc_task_manager()->workers();
2440   uint active_gc_threads = heap->gc_task_manager()->active_workers();
2441   TaskQueueSetSuper* qset = ParCompactionManager::region_array();
2442   ParallelTaskTerminator terminator(active_gc_threads, qset);
2443 
2444   GCTaskQueue* q = GCTaskQueue::create();
2445   prepare_region_draining_tasks(q, active_gc_threads);
2446   enqueue_dense_prefix_tasks(q, active_gc_threads);
2447   enqueue_region_stealing_tasks(q, &terminator, active_gc_threads);
2448 
2449   {
2450     GCTraceTime(Trace, gc, phases) tm("Par Compact", &_gc_timer);
2451 
2452     gc_task_manager()->execute_and_wait(q);
2453 
2454 #ifdef  ASSERT
2455     // Verify that all regions have been processed before the deferred updates.
2456     for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2457       verify_complete(SpaceId(id));
2458     }
2459 #endif
2460   }
2461 
2462   {
2463     // Update the deferred objects, if any.  Any compaction manager can be used.
2464     GCTraceTime(Trace, gc, phases) tm("Deferred Updates", &_gc_timer);
2465     ParCompactionManager* cm = ParCompactionManager::manager_array(0);
2466     for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2467       update_deferred_objects(cm, SpaceId(id));
2468     }
2469   }
2470 
2471   DEBUG_ONLY(write_block_fill_histogram());
2472 }
2473 
2474 #ifdef  ASSERT
2475 void PSParallelCompact::verify_complete(SpaceId space_id) {
2476   // All Regions between space bottom() to new_top() should be marked as filled
2477   // and all Regions between new_top() and top() should be available (i.e.,
2478   // should have been emptied).
2479   ParallelCompactData& sd = summary_data();
2480   SpaceInfo si = _space_info[space_id];
2481   HeapWord* new_top_addr = sd.region_align_up(si.new_top());
2482   HeapWord* old_top_addr = sd.region_align_up(si.space()->top());
2483   const size_t beg_region = sd.addr_to_region_idx(si.space()->bottom());
2484   const size_t new_top_region = sd.addr_to_region_idx(new_top_addr);
2485   const size_t old_top_region = sd.addr_to_region_idx(old_top_addr);
2486 
2487   bool issued_a_warning = false;
2488 
2489   size_t cur_region;
2490   for (cur_region = beg_region; cur_region < new_top_region; ++cur_region) {
2491     const RegionData* const c = sd.region(cur_region);
2492     if (!c->completed()) {
2493       log_warning(gc)("region " SIZE_FORMAT " not filled: destination_count=%u",
2494                       cur_region, c->destination_count());
2495       issued_a_warning = true;
2496     }
2497   }
2498 
2499   for (cur_region = new_top_region; cur_region < old_top_region; ++cur_region) {
2500     const RegionData* const c = sd.region(cur_region);
2501     if (!c->available()) {
2502       log_warning(gc)("region " SIZE_FORMAT " not empty: destination_count=%u",
2503                       cur_region, c->destination_count());
2504       issued_a_warning = true;
2505     }
2506   }
2507 
2508   if (issued_a_warning) {
2509     print_region_ranges();
2510   }
2511 }
2512 #endif  // #ifdef ASSERT
2513 
2514 inline void UpdateOnlyClosure::do_addr(HeapWord* addr) {
2515   _start_array->allocate_block(addr);
2516   compaction_manager()->update_contents(oop(addr));
2517 }
2518 
2519 // Update interior oops in the ranges of regions [beg_region, end_region).
2520 void
2521 PSParallelCompact::update_and_deadwood_in_dense_prefix(ParCompactionManager* cm,
2522                                                        SpaceId space_id,
2523                                                        size_t beg_region,
2524                                                        size_t end_region) {
2525   ParallelCompactData& sd = summary_data();
2526   ParMarkBitMap* const mbm = mark_bitmap();
2527 
2528   HeapWord* beg_addr = sd.region_to_addr(beg_region);
2529   HeapWord* const end_addr = sd.region_to_addr(end_region);
2530   assert(beg_region <= end_region, "bad region range");
2531   assert(end_addr <= dense_prefix(space_id), "not in the dense prefix");
2532 
2533 #ifdef  ASSERT
2534   // Claim the regions to avoid triggering an assert when they are marked as
2535   // filled.
2536   for (size_t claim_region = beg_region; claim_region < end_region; ++claim_region) {
2537     assert(sd.region(claim_region)->claim_unsafe(), "claim() failed");
2538   }
2539 #endif  // #ifdef ASSERT
2540 
2541   if (beg_addr != space(space_id)->bottom()) {
2542     // Find the first live object or block of dead space that *starts* in this
2543     // range of regions.  If a partial object crosses onto the region, skip it;
2544     // it will be marked for 'deferred update' when the object head is
2545     // processed.  If dead space crosses onto the region, it is also skipped; it
2546     // will be filled when the prior region is processed.  If neither of those
2547     // apply, the first word in the region is the start of a live object or dead
2548     // space.
2549     assert(beg_addr > space(space_id)->bottom(), "sanity");
2550     const RegionData* const cp = sd.region(beg_region);
2551     if (cp->partial_obj_size() != 0) {
2552       beg_addr = sd.partial_obj_end(beg_region);
2553     } else if (dead_space_crosses_boundary(cp, mbm->addr_to_bit(beg_addr))) {
2554       beg_addr = mbm->find_obj_beg(beg_addr, end_addr);
2555     }
2556   }
2557 
2558   if (beg_addr < end_addr) {
2559     // A live object or block of dead space starts in this range of Regions.
2560      HeapWord* const dense_prefix_end = dense_prefix(space_id);
2561 
2562     // Create closures and iterate.
2563     UpdateOnlyClosure update_closure(mbm, cm, space_id);
2564     FillClosure fill_closure(cm, space_id);
2565     ParMarkBitMap::IterationStatus status;
2566     status = mbm->iterate(&update_closure, &fill_closure, beg_addr, end_addr,
2567                           dense_prefix_end);
2568     if (status == ParMarkBitMap::incomplete) {
2569       update_closure.do_addr(update_closure.source());
2570     }
2571   }
2572 
2573   // Mark the regions as filled.
2574   RegionData* const beg_cp = sd.region(beg_region);
2575   RegionData* const end_cp = sd.region(end_region);
2576   for (RegionData* cp = beg_cp; cp < end_cp; ++cp) {
2577     cp->set_completed();
2578   }
2579 }
2580 
2581 // Return the SpaceId for the space containing addr.  If addr is not in the
2582 // heap, last_space_id is returned.  In debug mode it expects the address to be
2583 // in the heap and asserts such.
2584 PSParallelCompact::SpaceId PSParallelCompact::space_id(HeapWord* addr) {
2585   assert(ParallelScavengeHeap::heap()->is_in_reserved(addr), "addr not in the heap");
2586 
2587   for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2588     if (_space_info[id].space()->contains(addr)) {
2589       return SpaceId(id);
2590     }
2591   }
2592 
2593   assert(false, "no space contains the addr");
2594   return last_space_id;
2595 }
2596 
2597 void PSParallelCompact::update_deferred_objects(ParCompactionManager* cm,
2598                                                 SpaceId id) {
2599   assert(id < last_space_id, "bad space id");
2600 
2601   ParallelCompactData& sd = summary_data();
2602   const SpaceInfo* const space_info = _space_info + id;
2603   ObjectStartArray* const start_array = space_info->start_array();
2604 
2605   const MutableSpace* const space = space_info->space();
2606   assert(space_info->dense_prefix() >= space->bottom(), "dense_prefix not set");
2607   HeapWord* const beg_addr = space_info->dense_prefix();
2608   HeapWord* const end_addr = sd.region_align_up(space_info->new_top());
2609 
2610   const RegionData* const beg_region = sd.addr_to_region_ptr(beg_addr);
2611   const RegionData* const end_region = sd.addr_to_region_ptr(end_addr);
2612   const RegionData* cur_region;
2613   for (cur_region = beg_region; cur_region < end_region; ++cur_region) {
2614     HeapWord* const addr = cur_region->deferred_obj_addr();
2615     if (addr != NULL) {
2616       if (start_array != NULL) {
2617         start_array->allocate_block(addr);
2618       }
2619       cm->update_contents(oop(addr));
2620       assert(oop(addr)->is_oop_or_null(), "Expected an oop or NULL at " PTR_FORMAT, p2i(oop(addr)));
2621     }
2622   }
2623 }
2624 
2625 // Skip over count live words starting from beg, and return the address of the
2626 // next live word.  Unless marked, the word corresponding to beg is assumed to
2627 // be dead.  Callers must either ensure beg does not correspond to the middle of
2628 // an object, or account for those live words in some other way.  Callers must
2629 // also ensure that there are enough live words in the range [beg, end) to skip.
2630 HeapWord*
2631 PSParallelCompact::skip_live_words(HeapWord* beg, HeapWord* end, size_t count)
2632 {
2633   assert(count > 0, "sanity");
2634 
2635   ParMarkBitMap* m = mark_bitmap();
2636   idx_t bits_to_skip = m->words_to_bits(count);
2637   idx_t cur_beg = m->addr_to_bit(beg);
2638   const idx_t search_end = BitMap::word_align_up(m->addr_to_bit(end));
2639 
2640   do {
2641     cur_beg = m->find_obj_beg(cur_beg, search_end);
2642     idx_t cur_end = m->find_obj_end(cur_beg, search_end);
2643     const size_t obj_bits = cur_end - cur_beg + 1;
2644     if (obj_bits > bits_to_skip) {
2645       return m->bit_to_addr(cur_beg + bits_to_skip);
2646     }
2647     bits_to_skip -= obj_bits;
2648     cur_beg = cur_end + 1;
2649   } while (bits_to_skip > 0);
2650 
2651   // Skipping the desired number of words landed just past the end of an object.
2652   // Find the start of the next object.
2653   cur_beg = m->find_obj_beg(cur_beg, search_end);
2654   assert(cur_beg < m->addr_to_bit(end), "not enough live words to skip");
2655   return m->bit_to_addr(cur_beg);
2656 }
2657 
2658 HeapWord* PSParallelCompact::first_src_addr(HeapWord* const dest_addr,
2659                                             SpaceId src_space_id,
2660                                             size_t src_region_idx)
2661 {
2662   assert(summary_data().is_region_aligned(dest_addr), "not aligned");
2663 
2664   const SplitInfo& split_info = _space_info[src_space_id].split_info();
2665   if (split_info.dest_region_addr() == dest_addr) {
2666     // The partial object ending at the split point contains the first word to
2667     // be copied to dest_addr.
2668     return split_info.first_src_addr();
2669   }
2670 
2671   const ParallelCompactData& sd = summary_data();
2672   ParMarkBitMap* const bitmap = mark_bitmap();
2673   const size_t RegionSize = ParallelCompactData::RegionSize;
2674 
2675   assert(sd.is_region_aligned(dest_addr), "not aligned");
2676   const RegionData* const src_region_ptr = sd.region(src_region_idx);
2677   const size_t partial_obj_size = src_region_ptr->partial_obj_size();
2678   HeapWord* const src_region_destination = src_region_ptr->destination();
2679 
2680   assert(dest_addr >= src_region_destination, "wrong src region");
2681   assert(src_region_ptr->data_size() > 0, "src region cannot be empty");
2682 
2683   HeapWord* const src_region_beg = sd.region_to_addr(src_region_idx);
2684   HeapWord* const src_region_end = src_region_beg + RegionSize;
2685 
2686   HeapWord* addr = src_region_beg;
2687   if (dest_addr == src_region_destination) {
2688     // Return the first live word in the source region.
2689     if (partial_obj_size == 0) {
2690       addr = bitmap->find_obj_beg(addr, src_region_end);
2691       assert(addr < src_region_end, "no objects start in src region");
2692     }
2693     return addr;
2694   }
2695 
2696   // Must skip some live data.
2697   size_t words_to_skip = dest_addr - src_region_destination;
2698   assert(src_region_ptr->data_size() > words_to_skip, "wrong src region");
2699 
2700   if (partial_obj_size >= words_to_skip) {
2701     // All the live words to skip are part of the partial object.
2702     addr += words_to_skip;
2703     if (partial_obj_size == words_to_skip) {
2704       // Find the first live word past the partial object.
2705       addr = bitmap->find_obj_beg(addr, src_region_end);
2706       assert(addr < src_region_end, "wrong src region");
2707     }
2708     return addr;
2709   }
2710 
2711   // Skip over the partial object (if any).
2712   if (partial_obj_size != 0) {
2713     words_to_skip -= partial_obj_size;
2714     addr += partial_obj_size;
2715   }
2716 
2717   // Skip over live words due to objects that start in the region.
2718   addr = skip_live_words(addr, src_region_end, words_to_skip);
2719   assert(addr < src_region_end, "wrong src region");
2720   return addr;
2721 }
2722 
2723 void PSParallelCompact::decrement_destination_counts(ParCompactionManager* cm,
2724                                                      SpaceId src_space_id,
2725                                                      size_t beg_region,
2726                                                      HeapWord* end_addr)
2727 {
2728   ParallelCompactData& sd = summary_data();
2729 
2730 #ifdef ASSERT
2731   MutableSpace* const src_space = _space_info[src_space_id].space();
2732   HeapWord* const beg_addr = sd.region_to_addr(beg_region);
2733   assert(src_space->contains(beg_addr) || beg_addr == src_space->end(),
2734          "src_space_id does not match beg_addr");
2735   assert(src_space->contains(end_addr) || end_addr == src_space->end(),
2736          "src_space_id does not match end_addr");
2737 #endif // #ifdef ASSERT
2738 
2739   RegionData* const beg = sd.region(beg_region);
2740   RegionData* const end = sd.addr_to_region_ptr(sd.region_align_up(end_addr));
2741 
2742   // Regions up to new_top() are enqueued if they become available.
2743   HeapWord* const new_top = _space_info[src_space_id].new_top();
2744   RegionData* const enqueue_end =
2745     sd.addr_to_region_ptr(sd.region_align_up(new_top));
2746 
2747   for (RegionData* cur = beg; cur < end; ++cur) {
2748     assert(cur->data_size() > 0, "region must have live data");
2749     cur->decrement_destination_count();
2750     if (cur < enqueue_end && cur->available() && cur->claim()) {
2751       cm->push_region(sd.region(cur));
2752     }
2753   }
2754 }
2755 
2756 size_t PSParallelCompact::next_src_region(MoveAndUpdateClosure& closure,
2757                                           SpaceId& src_space_id,
2758                                           HeapWord*& src_space_top,
2759                                           HeapWord* end_addr)
2760 {
2761   typedef ParallelCompactData::RegionData RegionData;
2762 
2763   ParallelCompactData& sd = PSParallelCompact::summary_data();
2764   const size_t region_size = ParallelCompactData::RegionSize;
2765 
2766   size_t src_region_idx = 0;
2767 
2768   // Skip empty regions (if any) up to the top of the space.
2769   HeapWord* const src_aligned_up = sd.region_align_up(end_addr);
2770   RegionData* src_region_ptr = sd.addr_to_region_ptr(src_aligned_up);
2771   HeapWord* const top_aligned_up = sd.region_align_up(src_space_top);
2772   const RegionData* const top_region_ptr =
2773     sd.addr_to_region_ptr(top_aligned_up);
2774   while (src_region_ptr < top_region_ptr && src_region_ptr->data_size() == 0) {
2775     ++src_region_ptr;
2776   }
2777 
2778   if (src_region_ptr < top_region_ptr) {
2779     // The next source region is in the current space.  Update src_region_idx
2780     // and the source address to match src_region_ptr.
2781     src_region_idx = sd.region(src_region_ptr);
2782     HeapWord* const src_region_addr = sd.region_to_addr(src_region_idx);
2783     if (src_region_addr > closure.source()) {
2784       closure.set_source(src_region_addr);
2785     }
2786     return src_region_idx;
2787   }
2788 
2789   // Switch to a new source space and find the first non-empty region.
2790   unsigned int space_id = src_space_id + 1;
2791   assert(space_id < last_space_id, "not enough spaces");
2792 
2793   HeapWord* const destination = closure.destination();
2794 
2795   do {
2796     MutableSpace* space = _space_info[space_id].space();
2797     HeapWord* const bottom = space->bottom();
2798     const RegionData* const bottom_cp = sd.addr_to_region_ptr(bottom);
2799 
2800     // Iterate over the spaces that do not compact into themselves.
2801     if (bottom_cp->destination() != bottom) {
2802       HeapWord* const top_aligned_up = sd.region_align_up(space->top());
2803       const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
2804 
2805       for (const RegionData* src_cp = bottom_cp; src_cp < top_cp; ++src_cp) {
2806         if (src_cp->live_obj_size() > 0) {
2807           // Found it.
2808           assert(src_cp->destination() == destination,
2809                  "first live obj in the space must match the destination");
2810           assert(src_cp->partial_obj_size() == 0,
2811                  "a space cannot begin with a partial obj");
2812 
2813           src_space_id = SpaceId(space_id);
2814           src_space_top = space->top();
2815           const size_t src_region_idx = sd.region(src_cp);
2816           closure.set_source(sd.region_to_addr(src_region_idx));
2817           return src_region_idx;
2818         } else {
2819           assert(src_cp->data_size() == 0, "sanity");
2820         }
2821       }
2822     }
2823   } while (++space_id < last_space_id);
2824 
2825   assert(false, "no source region was found");
2826   return 0;
2827 }
2828 
2829 void PSParallelCompact::fill_region(ParCompactionManager* cm, size_t region_idx)
2830 {
2831   typedef ParMarkBitMap::IterationStatus IterationStatus;
2832   const size_t RegionSize = ParallelCompactData::RegionSize;
2833   ParMarkBitMap* const bitmap = mark_bitmap();
2834   ParallelCompactData& sd = summary_data();
2835   RegionData* const region_ptr = sd.region(region_idx);
2836 
2837   // Get the items needed to construct the closure.
2838   HeapWord* dest_addr = sd.region_to_addr(region_idx);
2839   SpaceId dest_space_id = space_id(dest_addr);
2840   ObjectStartArray* start_array = _space_info[dest_space_id].start_array();
2841   HeapWord* new_top = _space_info[dest_space_id].new_top();
2842   assert(dest_addr < new_top, "sanity");
2843   const size_t words = MIN2(pointer_delta(new_top, dest_addr), RegionSize);
2844 
2845   // Get the source region and related info.
2846   size_t src_region_idx = region_ptr->source_region();
2847   SpaceId src_space_id = space_id(sd.region_to_addr(src_region_idx));
2848   HeapWord* src_space_top = _space_info[src_space_id].space()->top();
2849 
2850   MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words);
2851   closure.set_source(first_src_addr(dest_addr, src_space_id, src_region_idx));
2852 
2853   // Adjust src_region_idx to prepare for decrementing destination counts (the
2854   // destination count is not decremented when a region is copied to itself).
2855   if (src_region_idx == region_idx) {
2856     src_region_idx += 1;
2857   }
2858 
2859   if (bitmap->is_unmarked(closure.source())) {
2860     // The first source word is in the middle of an object; copy the remainder
2861     // of the object or as much as will fit.  The fact that pointer updates were
2862     // deferred will be noted when the object header is processed.
2863     HeapWord* const old_src_addr = closure.source();
2864     closure.copy_partial_obj();
2865     if (closure.is_full()) {
2866       decrement_destination_counts(cm, src_space_id, src_region_idx,
2867                                    closure.source());
2868       region_ptr->set_deferred_obj_addr(NULL);
2869       region_ptr->set_completed();
2870       return;
2871     }
2872 
2873     HeapWord* const end_addr = sd.region_align_down(closure.source());
2874     if (sd.region_align_down(old_src_addr) != end_addr) {
2875       // The partial object was copied from more than one source region.
2876       decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
2877 
2878       // Move to the next source region, possibly switching spaces as well.  All
2879       // args except end_addr may be modified.
2880       src_region_idx = next_src_region(closure, src_space_id, src_space_top,
2881                                        end_addr);
2882     }
2883   }
2884 
2885   do {
2886     HeapWord* const cur_addr = closure.source();
2887     HeapWord* const end_addr = MIN2(sd.region_align_up(cur_addr + 1),
2888                                     src_space_top);
2889     IterationStatus status = bitmap->iterate(&closure, cur_addr, end_addr);
2890 
2891     if (status == ParMarkBitMap::incomplete) {
2892       // The last obj that starts in the source region does not end in the
2893       // region.
2894       assert(closure.source() < end_addr, "sanity");
2895       HeapWord* const obj_beg = closure.source();
2896       HeapWord* const range_end = MIN2(obj_beg + closure.words_remaining(),
2897                                        src_space_top);
2898       HeapWord* const obj_end = bitmap->find_obj_end(obj_beg, range_end);
2899       if (obj_end < range_end) {
2900         // The end was found; the entire object will fit.
2901         status = closure.do_addr(obj_beg, bitmap->obj_size(obj_beg, obj_end));
2902         assert(status != ParMarkBitMap::would_overflow, "sanity");
2903       } else {
2904         // The end was not found; the object will not fit.
2905         assert(range_end < src_space_top, "obj cannot cross space boundary");
2906         status = ParMarkBitMap::would_overflow;
2907       }
2908     }
2909 
2910     if (status == ParMarkBitMap::would_overflow) {
2911       // The last object did not fit.  Note that interior oop updates were
2912       // deferred, then copy enough of the object to fill the region.
2913       region_ptr->set_deferred_obj_addr(closure.destination());
2914       status = closure.copy_until_full(); // copies from closure.source()
2915 
2916       decrement_destination_counts(cm, src_space_id, src_region_idx,
2917                                    closure.source());
2918       region_ptr->set_completed();
2919       return;
2920     }
2921 
2922     if (status == ParMarkBitMap::full) {
2923       decrement_destination_counts(cm, src_space_id, src_region_idx,
2924                                    closure.source());
2925       region_ptr->set_deferred_obj_addr(NULL);
2926       region_ptr->set_completed();
2927       return;
2928     }
2929 
2930     decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
2931 
2932     // Move to the next source region, possibly switching spaces as well.  All
2933     // args except end_addr may be modified.
2934     src_region_idx = next_src_region(closure, src_space_id, src_space_top,
2935                                      end_addr);
2936   } while (true);
2937 }
2938 
2939 void PSParallelCompact::fill_blocks(size_t region_idx)
2940 {
2941   // Fill in the block table elements for the specified region.  Each block
2942   // table element holds the number of live words in the region that are to the
2943   // left of the first object that starts in the block.  Thus only blocks in
2944   // which an object starts need to be filled.
2945   //
2946   // The algorithm scans the section of the bitmap that corresponds to the
2947   // region, keeping a running total of the live words.  When an object start is
2948   // found, if it's the first to start in the block that contains it, the
2949   // current total is written to the block table element.
2950   const size_t Log2BlockSize = ParallelCompactData::Log2BlockSize;
2951   const size_t Log2RegionSize = ParallelCompactData::Log2RegionSize;
2952   const size_t RegionSize = ParallelCompactData::RegionSize;
2953 
2954   ParallelCompactData& sd = summary_data();
2955   const size_t partial_obj_size = sd.region(region_idx)->partial_obj_size();
2956   if (partial_obj_size >= RegionSize) {
2957     return; // No objects start in this region.
2958   }
2959 
2960   // Ensure the first loop iteration decides that the block has changed.
2961   size_t cur_block = sd.block_count();
2962 
2963   const ParMarkBitMap* const bitmap = mark_bitmap();
2964 
2965   const size_t Log2BitsPerBlock = Log2BlockSize - LogMinObjAlignment;
2966   assert((size_t)1 << Log2BitsPerBlock ==
2967          bitmap->words_to_bits(ParallelCompactData::BlockSize), "sanity");
2968 
2969   size_t beg_bit = bitmap->words_to_bits(region_idx << Log2RegionSize);
2970   const size_t range_end = beg_bit + bitmap->words_to_bits(RegionSize);
2971   size_t live_bits = bitmap->words_to_bits(partial_obj_size);
2972   beg_bit = bitmap->find_obj_beg(beg_bit + live_bits, range_end);
2973   while (beg_bit < range_end) {
2974     const size_t new_block = beg_bit >> Log2BitsPerBlock;
2975     if (new_block != cur_block) {
2976       cur_block = new_block;
2977       sd.block(cur_block)->set_offset(bitmap->bits_to_words(live_bits));
2978     }
2979 
2980     const size_t end_bit = bitmap->find_obj_end(beg_bit, range_end);
2981     if (end_bit < range_end - 1) {
2982       live_bits += end_bit - beg_bit + 1;
2983       beg_bit = bitmap->find_obj_beg(end_bit + 1, range_end);
2984     } else {
2985       return;
2986     }
2987   }
2988 }
2989 
2990 void
2991 PSParallelCompact::move_and_update(ParCompactionManager* cm, SpaceId space_id) {
2992   const MutableSpace* sp = space(space_id);
2993   if (sp->is_empty()) {
2994     return;
2995   }
2996 
2997   ParallelCompactData& sd = PSParallelCompact::summary_data();
2998   ParMarkBitMap* const bitmap = mark_bitmap();
2999   HeapWord* const dp_addr = dense_prefix(space_id);
3000   HeapWord* beg_addr = sp->bottom();
3001   HeapWord* end_addr = sp->top();
3002 
3003   assert(beg_addr <= dp_addr && dp_addr <= end_addr, "bad dense prefix");
3004 
3005   const size_t beg_region = sd.addr_to_region_idx(beg_addr);
3006   const size_t dp_region = sd.addr_to_region_idx(dp_addr);
3007   if (beg_region < dp_region) {
3008     update_and_deadwood_in_dense_prefix(cm, space_id, beg_region, dp_region);
3009   }
3010 
3011   // The destination of the first live object that starts in the region is one
3012   // past the end of the partial object entering the region (if any).
3013   HeapWord* const dest_addr = sd.partial_obj_end(dp_region);
3014   HeapWord* const new_top = _space_info[space_id].new_top();
3015   assert(new_top >= dest_addr, "bad new_top value");
3016   const size_t words = pointer_delta(new_top, dest_addr);
3017 
3018   if (words > 0) {
3019     ObjectStartArray* start_array = _space_info[space_id].start_array();
3020     MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words);
3021 
3022     ParMarkBitMap::IterationStatus status;
3023     status = bitmap->iterate(&closure, dest_addr, end_addr);
3024     assert(status == ParMarkBitMap::full, "iteration not complete");
3025     assert(bitmap->find_obj_beg(closure.source(), end_addr) == end_addr,
3026            "live objects skipped because closure is full");
3027   }
3028 }
3029 
3030 jlong PSParallelCompact::millis_since_last_gc() {
3031   // We need a monotonically non-decreasing time in ms but
3032   // os::javaTimeMillis() does not guarantee monotonicity.
3033   jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
3034   jlong ret_val = now - _time_of_last_gc;
3035   // XXX See note in genCollectedHeap::millis_since_last_gc().
3036   if (ret_val < 0) {
3037     NOT_PRODUCT(log_warning(gc)("time warp: " JLONG_FORMAT, ret_val);)
3038     return 0;
3039   }
3040   return ret_val;
3041 }
3042 
3043 void PSParallelCompact::reset_millis_since_last_gc() {
3044   // We need a monotonically non-decreasing time in ms but
3045   // os::javaTimeMillis() does not guarantee monotonicity.
3046   _time_of_last_gc = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
3047 }
3048 
3049 ParMarkBitMap::IterationStatus MoveAndUpdateClosure::copy_until_full()
3050 {
3051   if (source() != destination()) {
3052     DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3053     Copy::aligned_conjoint_words(source(), destination(), words_remaining());
3054   }
3055   update_state(words_remaining());
3056   assert(is_full(), "sanity");
3057   return ParMarkBitMap::full;
3058 }
3059 
3060 void MoveAndUpdateClosure::copy_partial_obj()
3061 {
3062   size_t words = words_remaining();
3063 
3064   HeapWord* const range_end = MIN2(source() + words, bitmap()->region_end());
3065   HeapWord* const end_addr = bitmap()->find_obj_end(source(), range_end);
3066   if (end_addr < range_end) {
3067     words = bitmap()->obj_size(source(), end_addr);
3068   }
3069 
3070   // This test is necessary; if omitted, the pointer updates to a partial object
3071   // that crosses the dense prefix boundary could be overwritten.
3072   if (source() != destination()) {
3073     DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3074     Copy::aligned_conjoint_words(source(), destination(), words);
3075   }
3076   update_state(words);
3077 }
3078 
3079 void InstanceKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) {
3080   PSParallelCompact::AdjustPointerClosure closure(cm);
3081   oop_oop_iterate_oop_maps<true>(obj, &closure);
3082 }
3083 
3084 void InstanceMirrorKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) {
3085   InstanceKlass::oop_pc_update_pointers(obj, cm);
3086 
3087   PSParallelCompact::AdjustPointerClosure closure(cm);
3088   oop_oop_iterate_statics<true>(obj, &closure);
3089 }
3090 
3091 void InstanceClassLoaderKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) {
3092   InstanceKlass::oop_pc_update_pointers(obj, cm);
3093 }
3094 
3095 #ifdef ASSERT
3096 template <class T> static void trace_reference_gc(const char *s, oop obj,
3097                                                   T* referent_addr,
3098                                                   T* next_addr,
3099                                                   T* discovered_addr) {
3100   log_develop_trace(gc, ref)("%s obj " PTR_FORMAT, s, p2i(obj));
3101   log_develop_trace(gc, ref)("     referent_addr/* " PTR_FORMAT " / " PTR_FORMAT,
3102                              p2i(referent_addr), referent_addr ? p2i(oopDesc::load_decode_heap_oop(referent_addr)) : NULL);
3103   log_develop_trace(gc, ref)("     next_addr/* " PTR_FORMAT " / " PTR_FORMAT,
3104                              p2i(next_addr), next_addr ? p2i(oopDesc::load_decode_heap_oop(next_addr)) : NULL);
3105   log_develop_trace(gc, ref)("     discovered_addr/* " PTR_FORMAT " / " PTR_FORMAT,
3106                              p2i(discovered_addr), discovered_addr ? p2i(oopDesc::load_decode_heap_oop(discovered_addr)) : NULL);
3107 }
3108 #endif
3109 
3110 template <class T>
3111 static void oop_pc_update_pointers_specialized(oop obj, ParCompactionManager* cm) {
3112   T* referent_addr = (T*)java_lang_ref_Reference::referent_addr(obj);
3113   PSParallelCompact::adjust_pointer(referent_addr, cm);
3114   T* next_addr = (T*)java_lang_ref_Reference::next_addr(obj);
3115   PSParallelCompact::adjust_pointer(next_addr, cm);
3116   T* discovered_addr = (T*)java_lang_ref_Reference::discovered_addr(obj);
3117   PSParallelCompact::adjust_pointer(discovered_addr, cm);
3118   debug_only(trace_reference_gc("InstanceRefKlass::oop_update_ptrs", obj,
3119                                 referent_addr, next_addr, discovered_addr);)
3120 }
3121 
3122 void InstanceRefKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) {
3123   InstanceKlass::oop_pc_update_pointers(obj, cm);
3124 
3125   if (UseCompressedOops) {
3126     oop_pc_update_pointers_specialized<narrowOop>(obj, cm);
3127   } else {
3128     oop_pc_update_pointers_specialized<oop>(obj, cm);
3129   }
3130 }
3131 
3132 void ObjArrayKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) {
3133   assert(obj->is_objArray(), "obj must be obj array");
3134   PSParallelCompact::AdjustPointerClosure closure(cm);
3135   oop_oop_iterate_elements<true>(objArrayOop(obj), &closure);
3136 }
3137 
3138 void TypeArrayKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) {
3139   assert(obj->is_typeArray(),"must be a type array");
3140 }
3141 
3142 ParMarkBitMapClosure::IterationStatus
3143 MoveAndUpdateClosure::do_addr(HeapWord* addr, size_t words) {
3144   assert(destination() != NULL, "sanity");
3145   assert(bitmap()->obj_size(addr) == words, "bad size");
3146 
3147   _source = addr;
3148   assert(PSParallelCompact::summary_data().calc_new_pointer(source(), compaction_manager()) ==
3149          destination(), "wrong destination");
3150 
3151   if (words > words_remaining()) {
3152     return ParMarkBitMap::would_overflow;
3153   }
3154 
3155   // The start_array must be updated even if the object is not moving.
3156   if (_start_array != NULL) {
3157     _start_array->allocate_block(destination());
3158   }
3159 
3160   if (destination() != source()) {
3161     DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3162     Copy::aligned_conjoint_words(source(), destination(), words);
3163   }
3164 
3165   oop moved_oop = (oop) destination();
3166   compaction_manager()->update_contents(moved_oop);
3167   assert(moved_oop->is_oop_or_null(), "Expected an oop or NULL at " PTR_FORMAT, p2i(moved_oop));
3168 
3169   update_state(words);
3170   assert(destination() == (HeapWord*)moved_oop + moved_oop->size(), "sanity");
3171   return is_full() ? ParMarkBitMap::full : ParMarkBitMap::incomplete;
3172 }
3173 
3174 UpdateOnlyClosure::UpdateOnlyClosure(ParMarkBitMap* mbm,
3175                                      ParCompactionManager* cm,
3176                                      PSParallelCompact::SpaceId space_id) :
3177   ParMarkBitMapClosure(mbm, cm),
3178   _space_id(space_id),
3179   _start_array(PSParallelCompact::start_array(space_id))
3180 {
3181 }
3182 
3183 // Updates the references in the object to their new values.
3184 ParMarkBitMapClosure::IterationStatus
3185 UpdateOnlyClosure::do_addr(HeapWord* addr, size_t words) {
3186   do_addr(addr);
3187   return ParMarkBitMap::incomplete;
3188 }
3189 
3190 ParMarkBitMapClosure::IterationStatus
3191 FillClosure::do_addr(HeapWord* addr, size_t size) {
3192   CollectedHeap::fill_with_objects(addr, size);
3193   HeapWord* const end = addr + size;
3194   do {
3195     _start_array->allocate_block(addr);
3196     addr += oop(addr)->size();
3197   } while (addr < end);
3198   return ParMarkBitMap::incomplete;
3199 }