1 /*
   2  * Copyright (c) 2005, 2018, 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 "aot/aotLoader.hpp"
  27 #include "classfile/classLoaderDataGraph.hpp"
  28 #include "classfile/javaClasses.inline.hpp"
  29 #include "classfile/stringTable.hpp"
  30 #include "classfile/symbolTable.hpp"
  31 #include "classfile/systemDictionary.hpp"
  32 #include "code/codeCache.hpp"
  33 #include "gc/parallel/gcTaskManager.hpp"
  34 #include "gc/parallel/parallelScavengeHeap.inline.hpp"
  35 #include "gc/parallel/parMarkBitMap.inline.hpp"
  36 #include "gc/parallel/pcTasks.hpp"
  37 #include "gc/parallel/psAdaptiveSizePolicy.hpp"
  38 #include "gc/parallel/psCompactionManager.inline.hpp"
  39 #include "gc/parallel/psOldGen.hpp"
  40 #include "gc/parallel/psParallelCompact.inline.hpp"
  41 #include "gc/parallel/psPromotionManager.inline.hpp"
  42 #include "gc/parallel/psScavenge.hpp"
  43 #include "gc/parallel/psYoungGen.hpp"
  44 #include "gc/shared/gcCause.hpp"
  45 #include "gc/shared/gcHeapSummary.hpp"
  46 #include "gc/shared/gcId.hpp"
  47 #include "gc/shared/gcLocker.hpp"
  48 #include "gc/shared/gcTimer.hpp"
  49 #include "gc/shared/gcTrace.hpp"
  50 #include "gc/shared/gcTraceTime.inline.hpp"
  51 #include "gc/shared/isGCActiveMark.hpp"
  52 #include "gc/shared/referencePolicy.hpp"
  53 #include "gc/shared/referenceProcessor.hpp"
  54 #include "gc/shared/referenceProcessorPhaseTimes.hpp"
  55 #include "gc/shared/spaceDecorator.hpp"
  56 #include "gc/shared/weakProcessor.hpp"
  57 #include "logging/log.hpp"
  58 #include "memory/iterator.inline.hpp"
  59 #include "memory/resourceArea.hpp"
  60 #include "oops/access.inline.hpp"
  61 #include "oops/instanceClassLoaderKlass.inline.hpp"
  62 #include "oops/instanceKlass.inline.hpp"
  63 #include "oops/instanceMirrorKlass.inline.hpp"
  64 #include "oops/methodData.hpp"
  65 #include "oops/objArrayKlass.inline.hpp"
  66 #include "oops/oop.inline.hpp"
  67 #include "runtime/atomic.hpp"
  68 #include "runtime/handles.inline.hpp"
  69 #include "runtime/safepoint.hpp"
  70 #include "runtime/vmThread.hpp"
  71 #include "services/management.hpp"
  72 #include "services/memTracker.hpp"
  73 #include "services/memoryService.hpp"
  74 #include "utilities/align.hpp"
  75 #include "utilities/debug.hpp"
  76 #include "utilities/events.hpp"
  77 #include "utilities/formatBuffer.hpp"
  78 #include "utilities/macros.hpp"
  79 #include "utilities/stack.inline.hpp"
  80 
  81 #include <math.h>
  82 
  83 // All sizes are in HeapWords.
  84 const size_t ParallelCompactData::Log2RegionSize  = 16; // 64K words
  85 const size_t ParallelCompactData::RegionSize      = (size_t)1 << Log2RegionSize;
  86 const size_t ParallelCompactData::RegionSizeBytes =
  87   RegionSize << LogHeapWordSize;
  88 const size_t ParallelCompactData::RegionSizeOffsetMask = RegionSize - 1;
  89 const size_t ParallelCompactData::RegionAddrOffsetMask = RegionSizeBytes - 1;
  90 const size_t ParallelCompactData::RegionAddrMask       = ~RegionAddrOffsetMask;
  91 
  92 const size_t ParallelCompactData::Log2BlockSize   = 7; // 128 words
  93 const size_t ParallelCompactData::BlockSize       = (size_t)1 << Log2BlockSize;
  94 const size_t ParallelCompactData::BlockSizeBytes  =
  95   BlockSize << LogHeapWordSize;
  96 const size_t ParallelCompactData::BlockSizeOffsetMask = BlockSize - 1;
  97 const size_t ParallelCompactData::BlockAddrOffsetMask = BlockSizeBytes - 1;
  98 const size_t ParallelCompactData::BlockAddrMask       = ~BlockAddrOffsetMask;
  99 
 100 const size_t ParallelCompactData::BlocksPerRegion = RegionSize / BlockSize;
 101 const size_t ParallelCompactData::Log2BlocksPerRegion =
 102   Log2RegionSize - Log2BlockSize;
 103 
 104 const ParallelCompactData::RegionData::region_sz_t
 105 ParallelCompactData::RegionData::dc_shift = 27;
 106 
 107 const ParallelCompactData::RegionData::region_sz_t
 108 ParallelCompactData::RegionData::dc_mask = ~0U << dc_shift;
 109 
 110 const ParallelCompactData::RegionData::region_sz_t
 111 ParallelCompactData::RegionData::dc_one = 0x1U << dc_shift;
 112 
 113 const ParallelCompactData::RegionData::region_sz_t
 114 ParallelCompactData::RegionData::los_mask = ~dc_mask;
 115 
 116 const ParallelCompactData::RegionData::region_sz_t
 117 ParallelCompactData::RegionData::dc_claimed = 0x8U << dc_shift;
 118 
 119 const ParallelCompactData::RegionData::region_sz_t
 120 ParallelCompactData::RegionData::dc_completed = 0xcU << dc_shift;
 121 
 122 SpaceInfo PSParallelCompact::_space_info[PSParallelCompact::last_space_id];
 123 
 124 SpanSubjectToDiscoveryClosure PSParallelCompact::_span_based_discoverer;
 125 ReferenceProcessor* PSParallelCompact::_ref_processor = NULL;
 126 
 127 double PSParallelCompact::_dwl_mean;
 128 double PSParallelCompact::_dwl_std_dev;
 129 double PSParallelCompact::_dwl_first_term;
 130 double PSParallelCompact::_dwl_adjustment;
 131 #ifdef  ASSERT
 132 bool   PSParallelCompact::_dwl_initialized = false;
 133 #endif  // #ifdef ASSERT
 134 
 135 void SplitInfo::record(size_t src_region_idx, size_t partial_obj_size,
 136                        HeapWord* destination)
 137 {
 138   assert(src_region_idx != 0, "invalid src_region_idx");
 139   assert(partial_obj_size != 0, "invalid partial_obj_size argument");
 140   assert(destination != NULL, "invalid destination argument");
 141 
 142   _src_region_idx = src_region_idx;
 143   _partial_obj_size = partial_obj_size;
 144   _destination = destination;
 145 
 146   // These fields may not be updated below, so make sure they're clear.
 147   assert(_dest_region_addr == NULL, "should have been cleared");
 148   assert(_first_src_addr == NULL, "should have been cleared");
 149 
 150   // Determine the number of destination regions for the partial object.
 151   HeapWord* const last_word = destination + partial_obj_size - 1;
 152   const ParallelCompactData& sd = PSParallelCompact::summary_data();
 153   HeapWord* const beg_region_addr = sd.region_align_down(destination);
 154   HeapWord* const end_region_addr = sd.region_align_down(last_word);
 155 
 156   if (beg_region_addr == end_region_addr) {
 157     // One destination region.
 158     _destination_count = 1;
 159     if (end_region_addr == destination) {
 160       // The destination falls on a region boundary, thus the first word of the
 161       // partial object will be the first word copied to the destination region.
 162       _dest_region_addr = end_region_addr;
 163       _first_src_addr = sd.region_to_addr(src_region_idx);
 164     }
 165   } else {
 166     // Two destination regions.  When copied, the partial object will cross a
 167     // destination region boundary, so a word somewhere within the partial
 168     // object will be the first word copied to the second destination region.
 169     _destination_count = 2;
 170     _dest_region_addr = end_region_addr;
 171     const size_t ofs = pointer_delta(end_region_addr, destination);
 172     assert(ofs < _partial_obj_size, "sanity");
 173     _first_src_addr = sd.region_to_addr(src_region_idx) + ofs;
 174   }
 175 }
 176 
 177 void SplitInfo::clear()
 178 {
 179   _src_region_idx = 0;
 180   _partial_obj_size = 0;
 181   _destination = NULL;
 182   _destination_count = 0;
 183   _dest_region_addr = NULL;
 184   _first_src_addr = NULL;
 185   assert(!is_valid(), "sanity");
 186 }
 187 
 188 #ifdef  ASSERT
 189 void SplitInfo::verify_clear()
 190 {
 191   assert(_src_region_idx == 0, "not clear");
 192   assert(_partial_obj_size == 0, "not clear");
 193   assert(_destination == NULL, "not clear");
 194   assert(_destination_count == 0, "not clear");
 195   assert(_dest_region_addr == NULL, "not clear");
 196   assert(_first_src_addr == NULL, "not clear");
 197 }
 198 #endif  // #ifdef ASSERT
 199 
 200 
 201 void PSParallelCompact::print_on_error(outputStream* st) {
 202   _mark_bitmap.print_on_error(st);
 203 }
 204 
 205 #ifndef PRODUCT
 206 const char* PSParallelCompact::space_names[] = {
 207   "old ", "eden", "from", "to  "
 208 };
 209 
 210 void PSParallelCompact::print_region_ranges() {
 211   if (!log_develop_is_enabled(Trace, gc, compaction)) {
 212     return;
 213   }
 214   Log(gc, compaction) log;
 215   ResourceMark rm;
 216   LogStream ls(log.trace());
 217   Universe::print_on(&ls);
 218   log.trace("space  bottom     top        end        new_top");
 219   log.trace("------ ---------- ---------- ---------- ----------");
 220 
 221   for (unsigned int id = 0; id < last_space_id; ++id) {
 222     const MutableSpace* space = _space_info[id].space();
 223     log.trace("%u %s "
 224               SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " "
 225               SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " ",
 226               id, space_names[id],
 227               summary_data().addr_to_region_idx(space->bottom()),
 228               summary_data().addr_to_region_idx(space->top()),
 229               summary_data().addr_to_region_idx(space->end()),
 230               summary_data().addr_to_region_idx(_space_info[id].new_top()));
 231   }
 232 }
 233 
 234 void
 235 print_generic_summary_region(size_t i, const ParallelCompactData::RegionData* c)
 236 {
 237 #define REGION_IDX_FORMAT        SIZE_FORMAT_W(7)
 238 #define REGION_DATA_FORMAT       SIZE_FORMAT_W(5)
 239 
 240   ParallelCompactData& sd = PSParallelCompact::summary_data();
 241   size_t dci = c->destination() ? sd.addr_to_region_idx(c->destination()) : 0;
 242   log_develop_trace(gc, compaction)(
 243       REGION_IDX_FORMAT " " PTR_FORMAT " "
 244       REGION_IDX_FORMAT " " PTR_FORMAT " "
 245       REGION_DATA_FORMAT " " REGION_DATA_FORMAT " "
 246       REGION_DATA_FORMAT " " REGION_IDX_FORMAT " %d",
 247       i, p2i(c->data_location()), dci, p2i(c->destination()),
 248       c->partial_obj_size(), c->live_obj_size(),
 249       c->data_size(), c->source_region(), c->destination_count());
 250 
 251 #undef  REGION_IDX_FORMAT
 252 #undef  REGION_DATA_FORMAT
 253 }
 254 
 255 void
 256 print_generic_summary_data(ParallelCompactData& summary_data,
 257                            HeapWord* const beg_addr,
 258                            HeapWord* const end_addr)
 259 {
 260   size_t total_words = 0;
 261   size_t i = summary_data.addr_to_region_idx(beg_addr);
 262   const size_t last = summary_data.addr_to_region_idx(end_addr);
 263   HeapWord* pdest = 0;
 264 
 265   while (i < last) {
 266     ParallelCompactData::RegionData* c = summary_data.region(i);
 267     if (c->data_size() != 0 || c->destination() != pdest) {
 268       print_generic_summary_region(i, c);
 269       total_words += c->data_size();
 270       pdest = c->destination();
 271     }
 272     ++i;
 273   }
 274 
 275   log_develop_trace(gc, compaction)("summary_data_bytes=" SIZE_FORMAT, total_words * HeapWordSize);
 276 }
 277 
 278 void
 279 PSParallelCompact::print_generic_summary_data(ParallelCompactData& summary_data,
 280                                               HeapWord* const beg_addr,
 281                                               HeapWord* const end_addr) {
 282   ::print_generic_summary_data(summary_data,beg_addr, end_addr);
 283 }
 284 
 285 void
 286 print_generic_summary_data(ParallelCompactData& summary_data,
 287                            SpaceInfo* space_info)
 288 {
 289   if (!log_develop_is_enabled(Trace, gc, compaction)) {
 290     return;
 291   }
 292 
 293   for (unsigned int id = 0; id < PSParallelCompact::last_space_id; ++id) {
 294     const MutableSpace* space = space_info[id].space();
 295     print_generic_summary_data(summary_data, space->bottom(),
 296                                MAX2(space->top(), space_info[id].new_top()));
 297   }
 298 }
 299 
 300 void
 301 print_initial_summary_data(ParallelCompactData& summary_data,
 302                            const MutableSpace* space) {
 303   if (space->top() == space->bottom()) {
 304     return;
 305   }
 306 
 307   const size_t region_size = ParallelCompactData::RegionSize;
 308   typedef ParallelCompactData::RegionData RegionData;
 309   HeapWord* const top_aligned_up = summary_data.region_align_up(space->top());
 310   const size_t end_region = summary_data.addr_to_region_idx(top_aligned_up);
 311   const RegionData* c = summary_data.region(end_region - 1);
 312   HeapWord* end_addr = c->destination() + c->data_size();
 313   const size_t live_in_space = pointer_delta(end_addr, space->bottom());
 314 
 315   // Print (and count) the full regions at the beginning of the space.
 316   size_t full_region_count = 0;
 317   size_t i = summary_data.addr_to_region_idx(space->bottom());
 318   while (i < end_region && summary_data.region(i)->data_size() == region_size) {
 319     ParallelCompactData::RegionData* c = summary_data.region(i);
 320     log_develop_trace(gc, compaction)(
 321         SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d",
 322         i, p2i(c->destination()),
 323         c->partial_obj_size(), c->live_obj_size(),
 324         c->data_size(), c->source_region(), c->destination_count());
 325     ++full_region_count;
 326     ++i;
 327   }
 328 
 329   size_t live_to_right = live_in_space - full_region_count * region_size;
 330 
 331   double max_reclaimed_ratio = 0.0;
 332   size_t max_reclaimed_ratio_region = 0;
 333   size_t max_dead_to_right = 0;
 334   size_t max_live_to_right = 0;
 335 
 336   // Print the 'reclaimed ratio' for regions while there is something live in
 337   // the region or to the right of it.  The remaining regions are empty (and
 338   // uninteresting), and computing the ratio will result in division by 0.
 339   while (i < end_region && live_to_right > 0) {
 340     c = summary_data.region(i);
 341     HeapWord* const region_addr = summary_data.region_to_addr(i);
 342     const size_t used_to_right = pointer_delta(space->top(), region_addr);
 343     const size_t dead_to_right = used_to_right - live_to_right;
 344     const double reclaimed_ratio = double(dead_to_right) / live_to_right;
 345 
 346     if (reclaimed_ratio > max_reclaimed_ratio) {
 347             max_reclaimed_ratio = reclaimed_ratio;
 348             max_reclaimed_ratio_region = i;
 349             max_dead_to_right = dead_to_right;
 350             max_live_to_right = live_to_right;
 351     }
 352 
 353     ParallelCompactData::RegionData* c = summary_data.region(i);
 354     log_develop_trace(gc, compaction)(
 355         SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d"
 356         "%12.10f " SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10),
 357         i, p2i(c->destination()),
 358         c->partial_obj_size(), c->live_obj_size(),
 359         c->data_size(), c->source_region(), c->destination_count(),
 360         reclaimed_ratio, dead_to_right, live_to_right);
 361 
 362 
 363     live_to_right -= c->data_size();
 364     ++i;
 365   }
 366 
 367   // Any remaining regions are empty.  Print one more if there is one.
 368   if (i < end_region) {
 369     ParallelCompactData::RegionData* c = summary_data.region(i);
 370     log_develop_trace(gc, compaction)(
 371         SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d",
 372          i, p2i(c->destination()),
 373          c->partial_obj_size(), c->live_obj_size(),
 374          c->data_size(), c->source_region(), c->destination_count());
 375   }
 376 
 377   log_develop_trace(gc, compaction)("max:  " SIZE_FORMAT_W(4) " d2r=" SIZE_FORMAT_W(10) " l2r=" SIZE_FORMAT_W(10) " max_ratio=%14.12f",
 378                                     max_reclaimed_ratio_region, max_dead_to_right, max_live_to_right, max_reclaimed_ratio);
 379 }
 380 
 381 void
 382 print_initial_summary_data(ParallelCompactData& summary_data,
 383                            SpaceInfo* space_info) {
 384   if (!log_develop_is_enabled(Trace, gc, compaction)) {
 385     return;
 386   }
 387 
 388   unsigned int id = PSParallelCompact::old_space_id;
 389   const MutableSpace* space;
 390   do {
 391     space = space_info[id].space();
 392     print_initial_summary_data(summary_data, space);
 393   } while (++id < PSParallelCompact::eden_space_id);
 394 
 395   do {
 396     space = space_info[id].space();
 397     print_generic_summary_data(summary_data, space->bottom(), space->top());
 398   } while (++id < PSParallelCompact::last_space_id);
 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_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(&add_obj_count);)
 532   DEBUG_ONLY(Atomic::add(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::post_initialize() {
 850   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
 851   _span_based_discoverer.set_span(heap->reserved_region());
 852   _ref_processor =
 853     new ReferenceProcessor(&_span_based_discoverer,
 854                            ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing
 855                            ParallelGCThreads,   // mt processing degree
 856                            true,                // mt discovery
 857                            ParallelGCThreads,   // mt discovery degree
 858                            true,                // atomic_discovery
 859                            &_is_alive_closure,  // non-header is alive closure
 860                            false);              // disable adjusting number of processing threads
 861   _counters = new CollectorCounters("PSParallelCompact", 1);
 862 
 863   // Initialize static fields in ParCompactionManager.
 864   ParCompactionManager::initialize(mark_bitmap());
 865 }
 866 
 867 bool PSParallelCompact::initialize() {
 868   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
 869   MemRegion mr = heap->reserved_region();
 870 
 871   // Was the old gen get allocated successfully?
 872   if (!heap->old_gen()->is_allocated()) {
 873     return false;
 874   }
 875 
 876   initialize_space_info();
 877   initialize_dead_wood_limiter();
 878 
 879   if (!_mark_bitmap.initialize(mr)) {
 880     vm_shutdown_during_initialization(
 881       err_msg("Unable to allocate " SIZE_FORMAT "KB bitmaps for parallel "
 882       "garbage collection for the requested " SIZE_FORMAT "KB heap.",
 883       _mark_bitmap.reserved_byte_size()/K, mr.byte_size()/K));
 884     return false;
 885   }
 886 
 887   if (!_summary_data.initialize(mr)) {
 888     vm_shutdown_during_initialization(
 889       err_msg("Unable to allocate " SIZE_FORMAT "KB card tables for parallel "
 890       "garbage collection for the requested " SIZE_FORMAT "KB heap.",
 891       _summary_data.reserved_byte_size()/K, mr.byte_size()/K));
 892     return false;
 893   }
 894 
 895   return true;
 896 }
 897 
 898 void PSParallelCompact::initialize_space_info()
 899 {
 900   memset(&_space_info, 0, sizeof(_space_info));
 901 
 902   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
 903   PSYoungGen* young_gen = heap->young_gen();
 904 
 905   _space_info[old_space_id].set_space(heap->old_gen()->object_space());
 906   _space_info[eden_space_id].set_space(young_gen->eden_space());
 907   _space_info[from_space_id].set_space(young_gen->from_space());
 908   _space_info[to_space_id].set_space(young_gen->to_space());
 909 
 910   _space_info[old_space_id].set_start_array(heap->old_gen()->start_array());
 911 }
 912 
 913 void PSParallelCompact::initialize_dead_wood_limiter()
 914 {
 915   const size_t max = 100;
 916   _dwl_mean = double(MIN2(ParallelOldDeadWoodLimiterMean, max)) / 100.0;
 917   _dwl_std_dev = double(MIN2(ParallelOldDeadWoodLimiterStdDev, max)) / 100.0;
 918   _dwl_first_term = 1.0 / (sqrt(2.0 * M_PI) * _dwl_std_dev);
 919   DEBUG_ONLY(_dwl_initialized = true;)
 920   _dwl_adjustment = normal_distribution(1.0);
 921 }
 922 
 923 void
 924 PSParallelCompact::clear_data_covering_space(SpaceId id)
 925 {
 926   // At this point, top is the value before GC, new_top() is the value that will
 927   // be set at the end of GC.  The marking bitmap is cleared to top; nothing
 928   // should be marked above top.  The summary data is cleared to the larger of
 929   // top & new_top.
 930   MutableSpace* const space = _space_info[id].space();
 931   HeapWord* const bot = space->bottom();
 932   HeapWord* const top = space->top();
 933   HeapWord* const max_top = MAX2(top, _space_info[id].new_top());
 934 
 935   const idx_t beg_bit = _mark_bitmap.addr_to_bit(bot);
 936   const idx_t end_bit = BitMap::word_align_up(_mark_bitmap.addr_to_bit(top));
 937   _mark_bitmap.clear_range(beg_bit, end_bit);
 938 
 939   const size_t beg_region = _summary_data.addr_to_region_idx(bot);
 940   const size_t end_region =
 941     _summary_data.addr_to_region_idx(_summary_data.region_align_up(max_top));
 942   _summary_data.clear_range(beg_region, end_region);
 943 
 944   // Clear the data used to 'split' regions.
 945   SplitInfo& split_info = _space_info[id].split_info();
 946   if (split_info.is_valid()) {
 947     split_info.clear();
 948   }
 949   DEBUG_ONLY(split_info.verify_clear();)
 950 }
 951 
 952 void PSParallelCompact::pre_compact()
 953 {
 954   // Update the from & to space pointers in space_info, since they are swapped
 955   // at each young gen gc.  Do the update unconditionally (even though a
 956   // promotion failure does not swap spaces) because an unknown number of young
 957   // collections will have swapped the spaces an unknown number of times.
 958   GCTraceTime(Debug, gc, phases) tm("Pre Compact", &_gc_timer);
 959   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
 960   _space_info[from_space_id].set_space(heap->young_gen()->from_space());
 961   _space_info[to_space_id].set_space(heap->young_gen()->to_space());
 962 
 963   DEBUG_ONLY(add_obj_count = add_obj_size = 0;)
 964   DEBUG_ONLY(mark_bitmap_count = mark_bitmap_size = 0;)
 965 
 966   // Increment the invocation count
 967   heap->increment_total_collections(true);
 968 
 969   // We need to track unique mark sweep invocations as well.
 970   _total_invocations++;
 971 
 972   heap->print_heap_before_gc();
 973   heap->trace_heap_before_gc(&_gc_tracer);
 974 
 975   // Fill in TLABs
 976   heap->ensure_parsability(true);  // retire TLABs
 977 
 978   if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
 979     HandleMark hm;  // Discard invalid handles created during verification
 980     Universe::verify("Before GC");
 981   }
 982 
 983   // Verify object start arrays
 984   if (VerifyObjectStartArray &&
 985       VerifyBeforeGC) {
 986     heap->old_gen()->verify_object_start_array();
 987   }
 988 
 989   DEBUG_ONLY(mark_bitmap()->verify_clear();)
 990   DEBUG_ONLY(summary_data().verify_clear();)
 991 
 992   // Have worker threads release resources the next time they run a task.
 993   gc_task_manager()->release_all_resources();
 994 
 995   ParCompactionManager::reset_all_bitmap_query_caches();
 996 }
 997 
 998 void PSParallelCompact::post_compact()
 999 {
1000   GCTraceTime(Info, gc, phases) tm("Post Compact", &_gc_timer);
1001 
1002   for (unsigned int id = old_space_id; id < last_space_id; ++id) {
1003     // Clear the marking bitmap, summary data and split info.
1004     clear_data_covering_space(SpaceId(id));
1005     // Update top().  Must be done after clearing the bitmap and summary data.
1006     _space_info[id].publish_new_top();
1007   }
1008 
1009   MutableSpace* const eden_space = _space_info[eden_space_id].space();
1010   MutableSpace* const from_space = _space_info[from_space_id].space();
1011   MutableSpace* const to_space   = _space_info[to_space_id].space();
1012 
1013   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
1014   bool eden_empty = eden_space->is_empty();
1015   if (!eden_empty) {
1016     eden_empty = absorb_live_data_from_eden(heap->size_policy(),
1017                                             heap->young_gen(), heap->old_gen());
1018   }
1019 
1020   // Update heap occupancy information which is used as input to the soft ref
1021   // clearing policy at the next gc.
1022   Universe::update_heap_info_at_gc();
1023 
1024   bool young_gen_empty = eden_empty && from_space->is_empty() &&
1025     to_space->is_empty();
1026 
1027   PSCardTable* ct = heap->card_table();
1028   MemRegion old_mr = heap->old_gen()->reserved();
1029   if (young_gen_empty) {
1030     ct->clear(MemRegion(old_mr.start(), old_mr.end()));
1031   } else {
1032     ct->invalidate(MemRegion(old_mr.start(), old_mr.end()));
1033   }
1034 
1035   // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1036   ClassLoaderDataGraph::purge();
1037   MetaspaceUtils::verify_metrics();
1038 
1039   CodeCache::gc_epilogue();
1040   JvmtiExport::gc_epilogue();
1041 
1042 #if COMPILER2_OR_JVMCI
1043   DerivedPointerTable::update_pointers();
1044 #endif
1045 
1046   if (ZapUnusedHeapArea) {
1047     heap->gen_mangle_unused_area();
1048   }
1049 
1050   // Update time of last GC
1051   reset_millis_since_last_gc();
1052 }
1053 
1054 HeapWord*
1055 PSParallelCompact::compute_dense_prefix_via_density(const SpaceId id,
1056                                                     bool maximum_compaction)
1057 {
1058   const size_t region_size = ParallelCompactData::RegionSize;
1059   const ParallelCompactData& sd = summary_data();
1060 
1061   const MutableSpace* const space = _space_info[id].space();
1062   HeapWord* const top_aligned_up = sd.region_align_up(space->top());
1063   const RegionData* const beg_cp = sd.addr_to_region_ptr(space->bottom());
1064   const RegionData* const end_cp = sd.addr_to_region_ptr(top_aligned_up);
1065 
1066   // Skip full regions at the beginning of the space--they are necessarily part
1067   // of the dense prefix.
1068   size_t full_count = 0;
1069   const RegionData* cp;
1070   for (cp = beg_cp; cp < end_cp && cp->data_size() == region_size; ++cp) {
1071     ++full_count;
1072   }
1073 
1074   assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");
1075   const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;
1076   const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval;
1077   if (maximum_compaction || cp == end_cp || interval_ended) {
1078     _maximum_compaction_gc_num = total_invocations();
1079     return sd.region_to_addr(cp);
1080   }
1081 
1082   HeapWord* const new_top = _space_info[id].new_top();
1083   const size_t space_live = pointer_delta(new_top, space->bottom());
1084   const size_t space_used = space->used_in_words();
1085   const size_t space_capacity = space->capacity_in_words();
1086 
1087   const double cur_density = double(space_live) / space_capacity;
1088   const double deadwood_density =
1089     (1.0 - cur_density) * (1.0 - cur_density) * cur_density * cur_density;
1090   const size_t deadwood_goal = size_t(space_capacity * deadwood_density);
1091 
1092   if (TraceParallelOldGCDensePrefix) {
1093     tty->print_cr("cur_dens=%5.3f dw_dens=%5.3f dw_goal=" SIZE_FORMAT,
1094                   cur_density, deadwood_density, deadwood_goal);
1095     tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " "
1096                   "space_cap=" SIZE_FORMAT,
1097                   space_live, space_used,
1098                   space_capacity);
1099   }
1100 
1101   // XXX - Use binary search?
1102   HeapWord* dense_prefix = sd.region_to_addr(cp);
1103   const RegionData* full_cp = cp;
1104   const RegionData* const top_cp = sd.addr_to_region_ptr(space->top() - 1);
1105   while (cp < end_cp) {
1106     HeapWord* region_destination = cp->destination();
1107     const size_t cur_deadwood = pointer_delta(dense_prefix, region_destination);
1108     if (TraceParallelOldGCDensePrefix && Verbose) {
1109       tty->print_cr("c#=" SIZE_FORMAT_W(4) " dst=" PTR_FORMAT " "
1110                     "dp=" PTR_FORMAT " " "cdw=" SIZE_FORMAT_W(8),
1111                     sd.region(cp), p2i(region_destination),
1112                     p2i(dense_prefix), cur_deadwood);
1113     }
1114 
1115     if (cur_deadwood >= deadwood_goal) {
1116       // Found the region that has the correct amount of deadwood to the left.
1117       // This typically occurs after crossing a fairly sparse set of regions, so
1118       // iterate backwards over those sparse regions, looking for the region
1119       // that has the lowest density of live objects 'to the right.'
1120       size_t space_to_left = sd.region(cp) * region_size;
1121       size_t live_to_left = space_to_left - cur_deadwood;
1122       size_t space_to_right = space_capacity - space_to_left;
1123       size_t live_to_right = space_live - live_to_left;
1124       double density_to_right = double(live_to_right) / space_to_right;
1125       while (cp > full_cp) {
1126         --cp;
1127         const size_t prev_region_live_to_right = live_to_right -
1128           cp->data_size();
1129         const size_t prev_region_space_to_right = space_to_right + region_size;
1130         double prev_region_density_to_right =
1131           double(prev_region_live_to_right) / prev_region_space_to_right;
1132         if (density_to_right <= prev_region_density_to_right) {
1133           return dense_prefix;
1134         }
1135         if (TraceParallelOldGCDensePrefix && Verbose) {
1136           tty->print_cr("backing up from c=" SIZE_FORMAT_W(4) " d2r=%10.8f "
1137                         "pc_d2r=%10.8f", sd.region(cp), density_to_right,
1138                         prev_region_density_to_right);
1139         }
1140         dense_prefix -= region_size;
1141         live_to_right = prev_region_live_to_right;
1142         space_to_right = prev_region_space_to_right;
1143         density_to_right = prev_region_density_to_right;
1144       }
1145       return dense_prefix;
1146     }
1147 
1148     dense_prefix += region_size;
1149     ++cp;
1150   }
1151 
1152   return dense_prefix;
1153 }
1154 
1155 #ifndef PRODUCT
1156 void PSParallelCompact::print_dense_prefix_stats(const char* const algorithm,
1157                                                  const SpaceId id,
1158                                                  const bool maximum_compaction,
1159                                                  HeapWord* const addr)
1160 {
1161   const size_t region_idx = summary_data().addr_to_region_idx(addr);
1162   RegionData* const cp = summary_data().region(region_idx);
1163   const MutableSpace* const space = _space_info[id].space();
1164   HeapWord* const new_top = _space_info[id].new_top();
1165 
1166   const size_t space_live = pointer_delta(new_top, space->bottom());
1167   const size_t dead_to_left = pointer_delta(addr, cp->destination());
1168   const size_t space_cap = space->capacity_in_words();
1169   const double dead_to_left_pct = double(dead_to_left) / space_cap;
1170   const size_t live_to_right = new_top - cp->destination();
1171   const size_t dead_to_right = space->top() - addr - live_to_right;
1172 
1173   tty->print_cr("%s=" PTR_FORMAT " dpc=" SIZE_FORMAT_W(5) " "
1174                 "spl=" SIZE_FORMAT " "
1175                 "d2l=" SIZE_FORMAT " d2l%%=%6.4f "
1176                 "d2r=" SIZE_FORMAT " l2r=" SIZE_FORMAT
1177                 " ratio=%10.8f",
1178                 algorithm, p2i(addr), region_idx,
1179                 space_live,
1180                 dead_to_left, dead_to_left_pct,
1181                 dead_to_right, live_to_right,
1182                 double(dead_to_right) / live_to_right);
1183 }
1184 #endif  // #ifndef PRODUCT
1185 
1186 // Return a fraction indicating how much of the generation can be treated as
1187 // "dead wood" (i.e., not reclaimed).  The function uses a normal distribution
1188 // based on the density of live objects in the generation to determine a limit,
1189 // which is then adjusted so the return value is min_percent when the density is
1190 // 1.
1191 //
1192 // The following table shows some return values for a different values of the
1193 // standard deviation (ParallelOldDeadWoodLimiterStdDev); the mean is 0.5 and
1194 // min_percent is 1.
1195 //
1196 //                          fraction allowed as dead wood
1197 //         -----------------------------------------------------------------
1198 // density std_dev=70 std_dev=75 std_dev=80 std_dev=85 std_dev=90 std_dev=95
1199 // ------- ---------- ---------- ---------- ---------- ---------- ----------
1200 // 0.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
1201 // 0.05000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
1202 // 0.10000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
1203 // 0.15000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
1204 // 0.20000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
1205 // 0.25000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
1206 // 0.30000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
1207 // 0.35000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
1208 // 0.40000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
1209 // 0.45000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
1210 // 0.50000 0.13832410 0.11599237 0.09847664 0.08456518 0.07338887 0.06431510
1211 // 0.55000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
1212 // 0.60000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
1213 // 0.65000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
1214 // 0.70000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
1215 // 0.75000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
1216 // 0.80000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
1217 // 0.85000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
1218 // 0.90000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
1219 // 0.95000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
1220 // 1.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
1221 
1222 double PSParallelCompact::dead_wood_limiter(double density, size_t min_percent)
1223 {
1224   assert(_dwl_initialized, "uninitialized");
1225 
1226   // The raw limit is the value of the normal distribution at x = density.
1227   const double raw_limit = normal_distribution(density);
1228 
1229   // Adjust the raw limit so it becomes the minimum when the density is 1.
1230   //
1231   // First subtract the adjustment value (which is simply the precomputed value
1232   // normal_distribution(1.0)); this yields a value of 0 when the density is 1.
1233   // Then add the minimum value, so the minimum is returned when the density is
1234   // 1.  Finally, prevent negative values, which occur when the mean is not 0.5.
1235   const double min = double(min_percent) / 100.0;
1236   const double limit = raw_limit - _dwl_adjustment + min;
1237   return MAX2(limit, 0.0);
1238 }
1239 
1240 ParallelCompactData::RegionData*
1241 PSParallelCompact::first_dead_space_region(const RegionData* beg,
1242                                            const RegionData* end)
1243 {
1244   const size_t region_size = ParallelCompactData::RegionSize;
1245   ParallelCompactData& sd = summary_data();
1246   size_t left = sd.region(beg);
1247   size_t right = end > beg ? sd.region(end) - 1 : left;
1248 
1249   // Binary search.
1250   while (left < right) {
1251     // Equivalent to (left + right) / 2, but does not overflow.
1252     const size_t middle = left + (right - left) / 2;
1253     RegionData* const middle_ptr = sd.region(middle);
1254     HeapWord* const dest = middle_ptr->destination();
1255     HeapWord* const addr = sd.region_to_addr(middle);
1256     assert(dest != NULL, "sanity");
1257     assert(dest <= addr, "must move left");
1258 
1259     if (middle > left && dest < addr) {
1260       right = middle - 1;
1261     } else if (middle < right && middle_ptr->data_size() == region_size) {
1262       left = middle + 1;
1263     } else {
1264       return middle_ptr;
1265     }
1266   }
1267   return sd.region(left);
1268 }
1269 
1270 ParallelCompactData::RegionData*
1271 PSParallelCompact::dead_wood_limit_region(const RegionData* beg,
1272                                           const RegionData* end,
1273                                           size_t dead_words)
1274 {
1275   ParallelCompactData& sd = summary_data();
1276   size_t left = sd.region(beg);
1277   size_t right = end > beg ? sd.region(end) - 1 : left;
1278 
1279   // Binary search.
1280   while (left < right) {
1281     // Equivalent to (left + right) / 2, but does not overflow.
1282     const size_t middle = left + (right - left) / 2;
1283     RegionData* const middle_ptr = sd.region(middle);
1284     HeapWord* const dest = middle_ptr->destination();
1285     HeapWord* const addr = sd.region_to_addr(middle);
1286     assert(dest != NULL, "sanity");
1287     assert(dest <= addr, "must move left");
1288 
1289     const size_t dead_to_left = pointer_delta(addr, dest);
1290     if (middle > left && dead_to_left > dead_words) {
1291       right = middle - 1;
1292     } else if (middle < right && dead_to_left < dead_words) {
1293       left = middle + 1;
1294     } else {
1295       return middle_ptr;
1296     }
1297   }
1298   return sd.region(left);
1299 }
1300 
1301 // The result is valid during the summary phase, after the initial summarization
1302 // of each space into itself, and before final summarization.
1303 inline double
1304 PSParallelCompact::reclaimed_ratio(const RegionData* const cp,
1305                                    HeapWord* const bottom,
1306                                    HeapWord* const top,
1307                                    HeapWord* const new_top)
1308 {
1309   ParallelCompactData& sd = summary_data();
1310 
1311   assert(cp != NULL, "sanity");
1312   assert(bottom != NULL, "sanity");
1313   assert(top != NULL, "sanity");
1314   assert(new_top != NULL, "sanity");
1315   assert(top >= new_top, "summary data problem?");
1316   assert(new_top > bottom, "space is empty; should not be here");
1317   assert(new_top >= cp->destination(), "sanity");
1318   assert(top >= sd.region_to_addr(cp), "sanity");
1319 
1320   HeapWord* const destination = cp->destination();
1321   const size_t dense_prefix_live  = pointer_delta(destination, bottom);
1322   const size_t compacted_region_live = pointer_delta(new_top, destination);
1323   const size_t compacted_region_used = pointer_delta(top,
1324                                                      sd.region_to_addr(cp));
1325   const size_t reclaimable = compacted_region_used - compacted_region_live;
1326 
1327   const double divisor = dense_prefix_live + 1.25 * compacted_region_live;
1328   return double(reclaimable) / divisor;
1329 }
1330 
1331 // Return the address of the end of the dense prefix, a.k.a. the start of the
1332 // compacted region.  The address is always on a region boundary.
1333 //
1334 // Completely full regions at the left are skipped, since no compaction can
1335 // occur in those regions.  Then the maximum amount of dead wood to allow is
1336 // computed, based on the density (amount live / capacity) of the generation;
1337 // the region with approximately that amount of dead space to the left is
1338 // identified as the limit region.  Regions between the last completely full
1339 // region and the limit region are scanned and the one that has the best
1340 // (maximum) reclaimed_ratio() is selected.
1341 HeapWord*
1342 PSParallelCompact::compute_dense_prefix(const SpaceId id,
1343                                         bool maximum_compaction)
1344 {
1345   const size_t region_size = ParallelCompactData::RegionSize;
1346   const ParallelCompactData& sd = summary_data();
1347 
1348   const MutableSpace* const space = _space_info[id].space();
1349   HeapWord* const top = space->top();
1350   HeapWord* const top_aligned_up = sd.region_align_up(top);
1351   HeapWord* const new_top = _space_info[id].new_top();
1352   HeapWord* const new_top_aligned_up = sd.region_align_up(new_top);
1353   HeapWord* const bottom = space->bottom();
1354   const RegionData* const beg_cp = sd.addr_to_region_ptr(bottom);
1355   const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
1356   const RegionData* const new_top_cp =
1357     sd.addr_to_region_ptr(new_top_aligned_up);
1358 
1359   // Skip full regions at the beginning of the space--they are necessarily part
1360   // of the dense prefix.
1361   const RegionData* const full_cp = first_dead_space_region(beg_cp, new_top_cp);
1362   assert(full_cp->destination() == sd.region_to_addr(full_cp) ||
1363          space->is_empty(), "no dead space allowed to the left");
1364   assert(full_cp->data_size() < region_size || full_cp == new_top_cp - 1,
1365          "region must have dead space");
1366 
1367   // The gc number is saved whenever a maximum compaction is done, and used to
1368   // determine when the maximum compaction interval has expired.  This avoids
1369   // successive max compactions for different reasons.
1370   assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");
1371   const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;
1372   const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval ||
1373     total_invocations() == HeapFirstMaximumCompactionCount;
1374   if (maximum_compaction || full_cp == top_cp || interval_ended) {
1375     _maximum_compaction_gc_num = total_invocations();
1376     return sd.region_to_addr(full_cp);
1377   }
1378 
1379   const size_t space_live = pointer_delta(new_top, bottom);
1380   const size_t space_used = space->used_in_words();
1381   const size_t space_capacity = space->capacity_in_words();
1382 
1383   const double density = double(space_live) / double(space_capacity);
1384   const size_t min_percent_free = MarkSweepDeadRatio;
1385   const double limiter = dead_wood_limiter(density, min_percent_free);
1386   const size_t dead_wood_max = space_used - space_live;
1387   const size_t dead_wood_limit = MIN2(size_t(space_capacity * limiter),
1388                                       dead_wood_max);
1389 
1390   if (TraceParallelOldGCDensePrefix) {
1391     tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " "
1392                   "space_cap=" SIZE_FORMAT,
1393                   space_live, space_used,
1394                   space_capacity);
1395     tty->print_cr("dead_wood_limiter(%6.4f, " SIZE_FORMAT ")=%6.4f "
1396                   "dead_wood_max=" SIZE_FORMAT " dead_wood_limit=" SIZE_FORMAT,
1397                   density, min_percent_free, limiter,
1398                   dead_wood_max, dead_wood_limit);
1399   }
1400 
1401   // Locate the region with the desired amount of dead space to the left.
1402   const RegionData* const limit_cp =
1403     dead_wood_limit_region(full_cp, top_cp, dead_wood_limit);
1404 
1405   // Scan from the first region with dead space to the limit region and find the
1406   // one with the best (largest) reclaimed ratio.
1407   double best_ratio = 0.0;
1408   const RegionData* best_cp = full_cp;
1409   for (const RegionData* cp = full_cp; cp < limit_cp; ++cp) {
1410     double tmp_ratio = reclaimed_ratio(cp, bottom, top, new_top);
1411     if (tmp_ratio > best_ratio) {
1412       best_cp = cp;
1413       best_ratio = tmp_ratio;
1414     }
1415   }
1416 
1417   return sd.region_to_addr(best_cp);
1418 }
1419 
1420 void PSParallelCompact::summarize_spaces_quick()
1421 {
1422   for (unsigned int i = 0; i < last_space_id; ++i) {
1423     const MutableSpace* space = _space_info[i].space();
1424     HeapWord** nta = _space_info[i].new_top_addr();
1425     bool result = _summary_data.summarize(_space_info[i].split_info(),
1426                                           space->bottom(), space->top(), NULL,
1427                                           space->bottom(), space->end(), nta);
1428     assert(result, "space must fit into itself");
1429     _space_info[i].set_dense_prefix(space->bottom());
1430   }
1431 }
1432 
1433 void PSParallelCompact::fill_dense_prefix_end(SpaceId id)
1434 {
1435   HeapWord* const dense_prefix_end = dense_prefix(id);
1436   const RegionData* region = _summary_data.addr_to_region_ptr(dense_prefix_end);
1437   const idx_t dense_prefix_bit = _mark_bitmap.addr_to_bit(dense_prefix_end);
1438   if (dead_space_crosses_boundary(region, dense_prefix_bit)) {
1439     // Only enough dead space is filled so that any remaining dead space to the
1440     // left is larger than the minimum filler object.  (The remainder is filled
1441     // during the copy/update phase.)
1442     //
1443     // The size of the dead space to the right of the boundary is not a
1444     // concern, since compaction will be able to use whatever space is
1445     // available.
1446     //
1447     // Here '||' is the boundary, 'x' represents a don't care bit and a box
1448     // surrounds the space to be filled with an object.
1449     //
1450     // In the 32-bit VM, each bit represents two 32-bit words:
1451     //                              +---+
1452     // a) beg_bits:  ...  x   x   x | 0 | ||   0   x  x  ...
1453     //    end_bits:  ...  x   x   x | 0 | ||   0   x  x  ...
1454     //                              +---+
1455     //
1456     // In the 64-bit VM, each bit represents one 64-bit word:
1457     //                              +------------+
1458     // b) beg_bits:  ...  x   x   x | 0   ||   0 | x  x  ...
1459     //    end_bits:  ...  x   x   1 | 0   ||   0 | x  x  ...
1460     //                              +------------+
1461     //                          +-------+
1462     // c) beg_bits:  ...  x   x | 0   0 | ||   0   x  x  ...
1463     //    end_bits:  ...  x   1 | 0   0 | ||   0   x  x  ...
1464     //                          +-------+
1465     //                      +-----------+
1466     // d) beg_bits:  ...  x | 0   0   0 | ||   0   x  x  ...
1467     //    end_bits:  ...  1 | 0   0   0 | ||   0   x  x  ...
1468     //                      +-----------+
1469     //                          +-------+
1470     // e) beg_bits:  ...  0   0 | 0   0 | ||   0   x  x  ...
1471     //    end_bits:  ...  0   0 | 0   0 | ||   0   x  x  ...
1472     //                          +-------+
1473 
1474     // Initially assume case a, c or e will apply.
1475     size_t obj_len = CollectedHeap::min_fill_size();
1476     HeapWord* obj_beg = dense_prefix_end - obj_len;
1477 
1478 #ifdef  _LP64
1479     if (MinObjAlignment > 1) { // object alignment > heap word size
1480       // Cases a, c or e.
1481     } else if (_mark_bitmap.is_obj_end(dense_prefix_bit - 2)) {
1482       // Case b above.
1483       obj_beg = dense_prefix_end - 1;
1484     } else if (!_mark_bitmap.is_obj_end(dense_prefix_bit - 3) &&
1485                _mark_bitmap.is_obj_end(dense_prefix_bit - 4)) {
1486       // Case d above.
1487       obj_beg = dense_prefix_end - 3;
1488       obj_len = 3;
1489     }
1490 #endif  // #ifdef _LP64
1491 
1492     CollectedHeap::fill_with_object(obj_beg, obj_len);
1493     _mark_bitmap.mark_obj(obj_beg, obj_len);
1494     _summary_data.add_obj(obj_beg, obj_len);
1495     assert(start_array(id) != NULL, "sanity");
1496     start_array(id)->allocate_block(obj_beg);
1497   }
1498 }
1499 
1500 void
1501 PSParallelCompact::summarize_space(SpaceId id, bool maximum_compaction)
1502 {
1503   assert(id < last_space_id, "id out of range");
1504   assert(_space_info[id].dense_prefix() == _space_info[id].space()->bottom(),
1505          "should have been reset in summarize_spaces_quick()");
1506 
1507   const MutableSpace* space = _space_info[id].space();
1508   if (_space_info[id].new_top() != space->bottom()) {
1509     HeapWord* dense_prefix_end = compute_dense_prefix(id, maximum_compaction);
1510     _space_info[id].set_dense_prefix(dense_prefix_end);
1511 
1512 #ifndef PRODUCT
1513     if (TraceParallelOldGCDensePrefix) {
1514       print_dense_prefix_stats("ratio", id, maximum_compaction,
1515                                dense_prefix_end);
1516       HeapWord* addr = compute_dense_prefix_via_density(id, maximum_compaction);
1517       print_dense_prefix_stats("density", id, maximum_compaction, addr);
1518     }
1519 #endif  // #ifndef PRODUCT
1520 
1521     // Recompute the summary data, taking into account the dense prefix.  If
1522     // every last byte will be reclaimed, then the existing summary data which
1523     // compacts everything can be left in place.
1524     if (!maximum_compaction && dense_prefix_end != space->bottom()) {
1525       // If dead space crosses the dense prefix boundary, it is (at least
1526       // partially) filled with a dummy object, marked live and added to the
1527       // summary data.  This simplifies the copy/update phase and must be done
1528       // before the final locations of objects are determined, to prevent
1529       // leaving a fragment of dead space that is too small to fill.
1530       fill_dense_prefix_end(id);
1531 
1532       // Compute the destination of each Region, and thus each object.
1533       _summary_data.summarize_dense_prefix(space->bottom(), dense_prefix_end);
1534       _summary_data.summarize(_space_info[id].split_info(),
1535                               dense_prefix_end, space->top(), NULL,
1536                               dense_prefix_end, space->end(),
1537                               _space_info[id].new_top_addr());
1538     }
1539   }
1540 
1541   if (log_develop_is_enabled(Trace, gc, compaction)) {
1542     const size_t region_size = ParallelCompactData::RegionSize;
1543     HeapWord* const dense_prefix_end = _space_info[id].dense_prefix();
1544     const size_t dp_region = _summary_data.addr_to_region_idx(dense_prefix_end);
1545     const size_t dp_words = pointer_delta(dense_prefix_end, space->bottom());
1546     HeapWord* const new_top = _space_info[id].new_top();
1547     const HeapWord* nt_aligned_up = _summary_data.region_align_up(new_top);
1548     const size_t cr_words = pointer_delta(nt_aligned_up, dense_prefix_end);
1549     log_develop_trace(gc, compaction)(
1550         "id=%d cap=" SIZE_FORMAT " dp=" PTR_FORMAT " "
1551         "dp_region=" SIZE_FORMAT " " "dp_count=" SIZE_FORMAT " "
1552         "cr_count=" SIZE_FORMAT " " "nt=" PTR_FORMAT,
1553         id, space->capacity_in_words(), p2i(dense_prefix_end),
1554         dp_region, dp_words / region_size,
1555         cr_words / region_size, p2i(new_top));
1556   }
1557 }
1558 
1559 #ifndef PRODUCT
1560 void PSParallelCompact::summary_phase_msg(SpaceId dst_space_id,
1561                                           HeapWord* dst_beg, HeapWord* dst_end,
1562                                           SpaceId src_space_id,
1563                                           HeapWord* src_beg, HeapWord* src_end)
1564 {
1565   log_develop_trace(gc, compaction)(
1566       "Summarizing %d [%s] into %d [%s]:  "
1567       "src=" PTR_FORMAT "-" PTR_FORMAT " "
1568       SIZE_FORMAT "-" SIZE_FORMAT " "
1569       "dst=" PTR_FORMAT "-" PTR_FORMAT " "
1570       SIZE_FORMAT "-" SIZE_FORMAT,
1571       src_space_id, space_names[src_space_id],
1572       dst_space_id, space_names[dst_space_id],
1573       p2i(src_beg), p2i(src_end),
1574       _summary_data.addr_to_region_idx(src_beg),
1575       _summary_data.addr_to_region_idx(src_end),
1576       p2i(dst_beg), p2i(dst_end),
1577       _summary_data.addr_to_region_idx(dst_beg),
1578       _summary_data.addr_to_region_idx(dst_end));
1579 }
1580 #endif  // #ifndef PRODUCT
1581 
1582 void PSParallelCompact::summary_phase(ParCompactionManager* cm,
1583                                       bool maximum_compaction)
1584 {
1585   GCTraceTime(Info, gc, phases) tm("Summary Phase", &_gc_timer);
1586 
1587 #ifdef  ASSERT
1588   if (TraceParallelOldGCMarkingPhase) {
1589     tty->print_cr("add_obj_count=" SIZE_FORMAT " "
1590                   "add_obj_bytes=" SIZE_FORMAT,
1591                   add_obj_count, add_obj_size * HeapWordSize);
1592     tty->print_cr("mark_bitmap_count=" SIZE_FORMAT " "
1593                   "mark_bitmap_bytes=" SIZE_FORMAT,
1594                   mark_bitmap_count, mark_bitmap_size * HeapWordSize);
1595   }
1596 #endif  // #ifdef ASSERT
1597 
1598   // Quick summarization of each space into itself, to see how much is live.
1599   summarize_spaces_quick();
1600 
1601   log_develop_trace(gc, compaction)("summary phase:  after summarizing each space to self");
1602   NOT_PRODUCT(print_region_ranges());
1603   NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info));
1604 
1605   // The amount of live data that will end up in old space (assuming it fits).
1606   size_t old_space_total_live = 0;
1607   for (unsigned int id = old_space_id; id < last_space_id; ++id) {
1608     old_space_total_live += pointer_delta(_space_info[id].new_top(),
1609                                           _space_info[id].space()->bottom());
1610   }
1611 
1612   MutableSpace* const old_space = _space_info[old_space_id].space();
1613   const size_t old_capacity = old_space->capacity_in_words();
1614   if (old_space_total_live > old_capacity) {
1615     // XXX - should also try to expand
1616     maximum_compaction = true;
1617   }
1618 
1619   // Old generations.
1620   summarize_space(old_space_id, maximum_compaction);
1621 
1622   // Summarize the remaining spaces in the young gen.  The initial target space
1623   // is the old gen.  If a space does not fit entirely into the target, then the
1624   // remainder is compacted into the space itself and that space becomes the new
1625   // target.
1626   SpaceId dst_space_id = old_space_id;
1627   HeapWord* dst_space_end = old_space->end();
1628   HeapWord** new_top_addr = _space_info[dst_space_id].new_top_addr();
1629   for (unsigned int id = eden_space_id; id < last_space_id; ++id) {
1630     const MutableSpace* space = _space_info[id].space();
1631     const size_t live = pointer_delta(_space_info[id].new_top(),
1632                                       space->bottom());
1633     const size_t available = pointer_delta(dst_space_end, *new_top_addr);
1634 
1635     NOT_PRODUCT(summary_phase_msg(dst_space_id, *new_top_addr, dst_space_end,
1636                                   SpaceId(id), space->bottom(), space->top());)
1637     if (live > 0 && live <= available) {
1638       // All the live data will fit.
1639       bool done = _summary_data.summarize(_space_info[id].split_info(),
1640                                           space->bottom(), space->top(),
1641                                           NULL,
1642                                           *new_top_addr, dst_space_end,
1643                                           new_top_addr);
1644       assert(done, "space must fit into old gen");
1645 
1646       // Reset the new_top value for the space.
1647       _space_info[id].set_new_top(space->bottom());
1648     } else if (live > 0) {
1649       // Attempt to fit part of the source space into the target space.
1650       HeapWord* next_src_addr = NULL;
1651       bool done = _summary_data.summarize(_space_info[id].split_info(),
1652                                           space->bottom(), space->top(),
1653                                           &next_src_addr,
1654                                           *new_top_addr, dst_space_end,
1655                                           new_top_addr);
1656       assert(!done, "space should not fit into old gen");
1657       assert(next_src_addr != NULL, "sanity");
1658 
1659       // The source space becomes the new target, so the remainder is compacted
1660       // within the space itself.
1661       dst_space_id = SpaceId(id);
1662       dst_space_end = space->end();
1663       new_top_addr = _space_info[id].new_top_addr();
1664       NOT_PRODUCT(summary_phase_msg(dst_space_id,
1665                                     space->bottom(), dst_space_end,
1666                                     SpaceId(id), next_src_addr, space->top());)
1667       done = _summary_data.summarize(_space_info[id].split_info(),
1668                                      next_src_addr, space->top(),
1669                                      NULL,
1670                                      space->bottom(), dst_space_end,
1671                                      new_top_addr);
1672       assert(done, "space must fit when compacted into itself");
1673       assert(*new_top_addr <= space->top(), "usage should not grow");
1674     }
1675   }
1676 
1677   log_develop_trace(gc, compaction)("Summary_phase:  after final summarization");
1678   NOT_PRODUCT(print_region_ranges());
1679   NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info));
1680 }
1681 
1682 // This method should contain all heap-specific policy for invoking a full
1683 // collection.  invoke_no_policy() will only attempt to compact the heap; it
1684 // will do nothing further.  If we need to bail out for policy reasons, scavenge
1685 // before full gc, or any other specialized behavior, it needs to be added here.
1686 //
1687 // Note that this method should only be called from the vm_thread while at a
1688 // safepoint.
1689 //
1690 // Note that the all_soft_refs_clear flag in the collector policy
1691 // may be true because this method can be called without intervening
1692 // activity.  For example when the heap space is tight and full measure
1693 // are being taken to free space.
1694 void PSParallelCompact::invoke(bool maximum_heap_compaction) {
1695   assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
1696   assert(Thread::current() == (Thread*)VMThread::vm_thread(),
1697          "should be in vm thread");
1698 
1699   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
1700   GCCause::Cause gc_cause = heap->gc_cause();
1701   assert(!heap->is_gc_active(), "not reentrant");
1702 
1703   PSAdaptiveSizePolicy* policy = heap->size_policy();
1704   IsGCActiveMark mark;
1705 
1706   if (ScavengeBeforeFullGC) {
1707     PSScavenge::invoke_no_policy();
1708   }
1709 
1710   const bool clear_all_soft_refs =
1711     heap->soft_ref_policy()->should_clear_all_soft_refs();
1712 
1713   PSParallelCompact::invoke_no_policy(clear_all_soft_refs ||
1714                                       maximum_heap_compaction);
1715 }
1716 
1717 // This method contains no policy. You should probably
1718 // be calling invoke() instead.
1719 bool PSParallelCompact::invoke_no_policy(bool maximum_heap_compaction) {
1720   assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
1721   assert(ref_processor() != NULL, "Sanity");
1722 
1723   if (GCLocker::check_active_before_gc()) {
1724     return false;
1725   }
1726 
1727   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
1728 
1729   GCIdMark gc_id_mark;
1730   _gc_timer.register_gc_start();
1731   _gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start());
1732 
1733   TimeStamp marking_start;
1734   TimeStamp compaction_start;
1735   TimeStamp collection_exit;
1736 
1737   GCCause::Cause gc_cause = heap->gc_cause();
1738   PSYoungGen* young_gen = heap->young_gen();
1739   PSOldGen* old_gen = heap->old_gen();
1740   PSAdaptiveSizePolicy* size_policy = heap->size_policy();
1741 
1742   // The scope of casr should end after code that can change
1743   // CollectorPolicy::_should_clear_all_soft_refs.
1744   ClearedAllSoftRefs casr(maximum_heap_compaction,
1745                           heap->soft_ref_policy());
1746 
1747   if (ZapUnusedHeapArea) {
1748     // Save information needed to minimize mangling
1749     heap->record_gen_tops_before_GC();
1750   }
1751 
1752   // Make sure data structures are sane, make the heap parsable, and do other
1753   // miscellaneous bookkeeping.
1754   pre_compact();
1755 
1756   PreGCValues pre_gc_values(heap);
1757 
1758   // Get the compaction manager reserved for the VM thread.
1759   ParCompactionManager* const vmthread_cm =
1760     ParCompactionManager::manager_array(gc_task_manager()->workers());
1761 
1762   {
1763     ResourceMark rm;
1764     HandleMark hm;
1765 
1766     // Set the number of GC threads to be used in this collection
1767     gc_task_manager()->set_active_gang();
1768     gc_task_manager()->task_idle_workers();
1769 
1770     GCTraceCPUTime tcpu;
1771     GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause, true);
1772 
1773     heap->pre_full_gc_dump(&_gc_timer);
1774 
1775     TraceCollectorStats tcs(counters());
1776     TraceMemoryManagerStats tms(heap->old_gc_manager(), gc_cause);
1777 
1778     if (log_is_enabled(Debug, gc, heap, exit)) {
1779       accumulated_time()->start();
1780     }
1781 
1782     // Let the size policy know we're starting
1783     size_policy->major_collection_begin();
1784 
1785     CodeCache::gc_prologue();
1786 
1787 #if COMPILER2_OR_JVMCI
1788     DerivedPointerTable::clear();
1789 #endif
1790 
1791     ref_processor()->enable_discovery();
1792     ref_processor()->setup_policy(maximum_heap_compaction);
1793 
1794     bool marked_for_unloading = false;
1795 
1796     marking_start.update();
1797     marking_phase(vmthread_cm, maximum_heap_compaction, &_gc_tracer);
1798 
1799     bool max_on_system_gc = UseMaximumCompactionOnSystemGC
1800       && GCCause::is_user_requested_gc(gc_cause);
1801     summary_phase(vmthread_cm, maximum_heap_compaction || max_on_system_gc);
1802 
1803 #if COMPILER2_OR_JVMCI
1804     assert(DerivedPointerTable::is_active(), "Sanity");
1805     DerivedPointerTable::set_active(false);
1806 #endif
1807 
1808     // adjust_roots() updates Universe::_intArrayKlassObj which is
1809     // needed by the compaction for filling holes in the dense prefix.
1810     adjust_roots(vmthread_cm);
1811 
1812     compaction_start.update();
1813     compact();
1814 
1815     // Reset the mark bitmap, summary data, and do other bookkeeping.  Must be
1816     // done before resizing.
1817     post_compact();
1818 
1819     // Let the size policy know we're done
1820     size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause);
1821 
1822     if (UseAdaptiveSizePolicy) {
1823       log_debug(gc, ergo)("AdaptiveSizeStart: collection: %d ", heap->total_collections());
1824       log_trace(gc, ergo)("old_gen_capacity: " SIZE_FORMAT " young_gen_capacity: " SIZE_FORMAT,
1825                           old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes());
1826 
1827       // Don't check if the size_policy is ready here.  Let
1828       // the size_policy check that internally.
1829       if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&
1830           AdaptiveSizePolicy::should_update_promo_stats(gc_cause)) {
1831         // Swap the survivor spaces if from_space is empty. The
1832         // resize_young_gen() called below is normally used after
1833         // a successful young GC and swapping of survivor spaces;
1834         // otherwise, it will fail to resize the young gen with
1835         // the current implementation.
1836         if (young_gen->from_space()->is_empty()) {
1837           young_gen->from_space()->clear(SpaceDecorator::Mangle);
1838           young_gen->swap_spaces();
1839         }
1840 
1841         // Calculate optimal free space amounts
1842         assert(young_gen->max_size() >
1843           young_gen->from_space()->capacity_in_bytes() +
1844           young_gen->to_space()->capacity_in_bytes(),
1845           "Sizes of space in young gen are out-of-bounds");
1846 
1847         size_t young_live = young_gen->used_in_bytes();
1848         size_t eden_live = young_gen->eden_space()->used_in_bytes();
1849         size_t old_live = old_gen->used_in_bytes();
1850         size_t cur_eden = young_gen->eden_space()->capacity_in_bytes();
1851         size_t max_old_gen_size = old_gen->max_gen_size();
1852         size_t max_eden_size = young_gen->max_size() -
1853           young_gen->from_space()->capacity_in_bytes() -
1854           young_gen->to_space()->capacity_in_bytes();
1855 
1856         // Used for diagnostics
1857         size_policy->clear_generation_free_space_flags();
1858 
1859         size_policy->compute_generations_free_space(young_live,
1860                                                     eden_live,
1861                                                     old_live,
1862                                                     cur_eden,
1863                                                     max_old_gen_size,
1864                                                     max_eden_size,
1865                                                     true /* full gc*/);
1866 
1867         size_policy->check_gc_overhead_limit(young_live,
1868                                              eden_live,
1869                                              max_old_gen_size,
1870                                              max_eden_size,
1871                                              true /* full gc*/,
1872                                              gc_cause,
1873                                              heap->soft_ref_policy());
1874 
1875         size_policy->decay_supplemental_growth(true /* full gc*/);
1876 
1877         heap->resize_old_gen(
1878           size_policy->calculated_old_free_size_in_bytes());
1879 
1880         heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(),
1881                                size_policy->calculated_survivor_size_in_bytes());
1882       }
1883 
1884       log_debug(gc, ergo)("AdaptiveSizeStop: collection: %d ", heap->total_collections());
1885     }
1886 
1887     if (UsePerfData) {
1888       PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters();
1889       counters->update_counters();
1890       counters->update_old_capacity(old_gen->capacity_in_bytes());
1891       counters->update_young_capacity(young_gen->capacity_in_bytes());
1892     }
1893 
1894     heap->resize_all_tlabs();
1895 
1896     // Resize the metaspace capacity after a collection
1897     MetaspaceGC::compute_new_size();
1898 
1899     if (log_is_enabled(Debug, gc, heap, exit)) {
1900       accumulated_time()->stop();
1901     }
1902 
1903     young_gen->print_used_change(pre_gc_values.young_gen_used());
1904     old_gen->print_used_change(pre_gc_values.old_gen_used());
1905     MetaspaceUtils::print_metaspace_change(pre_gc_values.metadata_used());
1906 
1907     // Track memory usage and detect low memory
1908     MemoryService::track_memory_usage();
1909     heap->update_counters();
1910     gc_task_manager()->release_idle_workers();
1911 
1912     heap->post_full_gc_dump(&_gc_timer);
1913   }
1914 
1915 #ifdef ASSERT
1916   for (size_t i = 0; i < ParallelGCThreads + 1; ++i) {
1917     ParCompactionManager* const cm =
1918       ParCompactionManager::manager_array(int(i));
1919     assert(cm->marking_stack()->is_empty(),       "should be empty");
1920     assert(cm->region_stack()->is_empty(), "Region stack " SIZE_FORMAT " is not empty", i);
1921   }
1922 #endif // ASSERT
1923 
1924   if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
1925     HandleMark hm;  // Discard invalid handles created during verification
1926     Universe::verify("After GC");
1927   }
1928 
1929   // Re-verify object start arrays
1930   if (VerifyObjectStartArray &&
1931       VerifyAfterGC) {
1932     old_gen->verify_object_start_array();
1933   }
1934 
1935   if (ZapUnusedHeapArea) {
1936     old_gen->object_space()->check_mangled_unused_area_complete();
1937   }
1938 
1939   NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
1940 
1941   collection_exit.update();
1942 
1943   heap->print_heap_after_gc();
1944   heap->trace_heap_after_gc(&_gc_tracer);
1945 
1946   log_debug(gc, task, time)("VM-Thread " JLONG_FORMAT " " JLONG_FORMAT " " JLONG_FORMAT,
1947                          marking_start.ticks(), compaction_start.ticks(),
1948                          collection_exit.ticks());
1949   gc_task_manager()->print_task_time_stamps();
1950 
1951 #ifdef TRACESPINNING
1952   ParallelTaskTerminator::print_termination_counts();
1953 #endif
1954 
1955   AdaptiveSizePolicyOutput::print(size_policy, heap->total_collections());
1956 
1957   _gc_timer.register_gc_end();
1958 
1959   _gc_tracer.report_dense_prefix(dense_prefix(old_space_id));
1960   _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions());
1961 
1962   return true;
1963 }
1964 
1965 bool PSParallelCompact::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
1966                                              PSYoungGen* young_gen,
1967                                              PSOldGen* old_gen) {
1968   MutableSpace* const eden_space = young_gen->eden_space();
1969   assert(!eden_space->is_empty(), "eden must be non-empty");
1970   assert(young_gen->virtual_space()->alignment() ==
1971          old_gen->virtual_space()->alignment(), "alignments do not match");
1972 
1973   if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) {
1974     return false;
1975   }
1976 
1977   // Both generations must be completely committed.
1978   if (young_gen->virtual_space()->uncommitted_size() != 0) {
1979     return false;
1980   }
1981   if (old_gen->virtual_space()->uncommitted_size() != 0) {
1982     return false;
1983   }
1984 
1985   // Figure out how much to take from eden.  Include the average amount promoted
1986   // in the total; otherwise the next young gen GC will simply bail out to a
1987   // full GC.
1988   const size_t alignment = old_gen->virtual_space()->alignment();
1989   const size_t eden_used = eden_space->used_in_bytes();
1990   const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average();
1991   const size_t absorb_size = align_up(eden_used + promoted, alignment);
1992   const size_t eden_capacity = eden_space->capacity_in_bytes();
1993 
1994   if (absorb_size >= eden_capacity) {
1995     return false; // Must leave some space in eden.
1996   }
1997 
1998   const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size;
1999   if (new_young_size < young_gen->min_gen_size()) {
2000     return false; // Respect young gen minimum size.
2001   }
2002 
2003   log_trace(heap, ergo)(" absorbing " SIZE_FORMAT "K:  "
2004                         "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K "
2005                         "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K "
2006                         "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ",
2007                         absorb_size / K,
2008                         eden_capacity / K, (eden_capacity - absorb_size) / K,
2009                         young_gen->from_space()->used_in_bytes() / K,
2010                         young_gen->to_space()->used_in_bytes() / K,
2011                         young_gen->capacity_in_bytes() / K, new_young_size / K);
2012 
2013   // Fill the unused part of the old gen.
2014   MutableSpace* const old_space = old_gen->object_space();
2015   HeapWord* const unused_start = old_space->top();
2016   size_t const unused_words = pointer_delta(old_space->end(), unused_start);
2017 
2018   if (unused_words > 0) {
2019     if (unused_words < CollectedHeap::min_fill_size()) {
2020       return false;  // If the old gen cannot be filled, must give up.
2021     }
2022     CollectedHeap::fill_with_objects(unused_start, unused_words);
2023   }
2024 
2025   // Take the live data from eden and set both top and end in the old gen to
2026   // eden top.  (Need to set end because reset_after_change() mangles the region
2027   // from end to virtual_space->high() in debug builds).
2028   HeapWord* const new_top = eden_space->top();
2029   old_gen->virtual_space()->expand_into(young_gen->virtual_space(),
2030                                         absorb_size);
2031   young_gen->reset_after_change();
2032   old_space->set_top(new_top);
2033   old_space->set_end(new_top);
2034   old_gen->reset_after_change();
2035 
2036   // Update the object start array for the filler object and the data from eden.
2037   ObjectStartArray* const start_array = old_gen->start_array();
2038   for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) {
2039     start_array->allocate_block(p);
2040   }
2041 
2042   // Could update the promoted average here, but it is not typically updated at
2043   // full GCs and the value to use is unclear.  Something like
2044   //
2045   // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc.
2046 
2047   size_policy->set_bytes_absorbed_from_eden(absorb_size);
2048   return true;
2049 }
2050 
2051 GCTaskManager* const PSParallelCompact::gc_task_manager() {
2052   assert(ParallelScavengeHeap::gc_task_manager() != NULL,
2053     "shouldn't return NULL");
2054   return ParallelScavengeHeap::gc_task_manager();
2055 }
2056 
2057 class PCAddThreadRootsMarkingTaskClosure : public ThreadClosure {
2058 private:
2059   GCTaskQueue* _q;
2060 
2061 public:
2062   PCAddThreadRootsMarkingTaskClosure(GCTaskQueue* q) : _q(q) { }
2063   void do_thread(Thread* t) {
2064     _q->enqueue(new ThreadRootsMarkingTask(t));
2065   }
2066 };
2067 
2068 void PSParallelCompact::marking_phase(ParCompactionManager* cm,
2069                                       bool maximum_heap_compaction,
2070                                       ParallelOldTracer *gc_tracer) {
2071   // Recursively traverse all live objects and mark them
2072   GCTraceTime(Info, gc, phases) tm("Marking Phase", &_gc_timer);
2073 
2074   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
2075   uint parallel_gc_threads = heap->gc_task_manager()->workers();
2076   uint active_gc_threads = heap->gc_task_manager()->active_workers();
2077   TaskQueueSetSuper* qset = ParCompactionManager::stack_array();
2078   ParallelTaskTerminator terminator(active_gc_threads, qset);
2079 
2080   ParCompactionManager::MarkAndPushClosure mark_and_push_closure(cm);
2081   ParCompactionManager::FollowStackClosure follow_stack_closure(cm);
2082 
2083   // Need new claim bits before marking starts.
2084   ClassLoaderDataGraph::clear_claimed_marks();
2085 
2086   {
2087     GCTraceTime(Debug, gc, phases) tm("Par Mark", &_gc_timer);
2088 
2089     ParallelScavengeHeap::ParStrongRootsScope psrs;
2090 
2091     GCTaskQueue* q = GCTaskQueue::create();
2092 
2093     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::universe));
2094     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jni_handles));
2095     // We scan the thread roots in parallel
2096     PCAddThreadRootsMarkingTaskClosure cl(q);
2097     Threads::java_threads_and_vm_thread_do(&cl);
2098     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::object_synchronizer));
2099     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::management));
2100     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::system_dictionary));
2101     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::class_loader_data));
2102     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jvmti));
2103     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::code_cache));
2104 
2105     if (active_gc_threads > 1) {
2106       for (uint j = 0; j < active_gc_threads; j++) {
2107         q->enqueue(new StealMarkingTask(&terminator));
2108       }
2109     }
2110 
2111     gc_task_manager()->execute_and_wait(q);
2112   }
2113 
2114   // Process reference objects found during marking
2115   {
2116     GCTraceTime(Debug, gc, phases) tm("Reference Processing", &_gc_timer);
2117 
2118     ReferenceProcessorStats stats;
2119     ReferenceProcessorPhaseTimes pt(&_gc_timer, ref_processor()->max_num_queues());
2120 
2121     if (ref_processor()->processing_is_mt()) {
2122       ref_processor()->set_active_mt_degree(active_gc_threads);
2123 
2124       RefProcTaskExecutor task_executor;
2125       stats = ref_processor()->process_discovered_references(
2126         is_alive_closure(), &mark_and_push_closure, &follow_stack_closure,
2127         &task_executor, &pt);
2128     } else {
2129       stats = ref_processor()->process_discovered_references(
2130         is_alive_closure(), &mark_and_push_closure, &follow_stack_closure, NULL,
2131         &pt);
2132     }
2133 
2134     gc_tracer->report_gc_reference_stats(stats);
2135     pt.print_all_references();
2136   }
2137 
2138   // This is the point where the entire marking should have completed.
2139   assert(cm->marking_stacks_empty(), "Marking should have completed");
2140 
2141   {
2142     GCTraceTime(Debug, gc, phases) tm("Weak Processing", &_gc_timer);
2143     WeakProcessor::weak_oops_do(is_alive_closure(), &do_nothing_cl);
2144   }
2145 
2146   {
2147     GCTraceTime(Debug, gc, phases) tm_m("Class Unloading", &_gc_timer);
2148 
2149     // Follow system dictionary roots and unload classes.
2150     bool purged_class = SystemDictionary::do_unloading(&_gc_timer);
2151 
2152     // Unload nmethods.
2153     CodeCache::do_unloading(is_alive_closure(), purged_class);
2154 
2155     // Prune dead klasses from subklass/sibling/implementor lists.
2156     Klass::clean_weak_klass_links(purged_class);
2157   }
2158 
2159   {
2160     GCTraceTime(Debug, gc, phases) t("Scrub String Table", &_gc_timer);
2161     // Delete entries for dead interned strings.
2162     StringTable::unlink(is_alive_closure());
2163   }
2164 
2165   {
2166     GCTraceTime(Debug, gc, phases) t("Scrub Symbol Table", &_gc_timer);
2167     // Clean up unreferenced symbols in symbol table.
2168     SymbolTable::unlink();
2169   }
2170 
2171   _gc_tracer.report_object_count_after_gc(is_alive_closure());
2172 }
2173 
2174 void PSParallelCompact::adjust_roots(ParCompactionManager* cm) {
2175   // Adjust the pointers to reflect the new locations
2176   GCTraceTime(Info, gc, phases) tm("Adjust Roots", &_gc_timer);
2177 
2178   // Need new claim bits when tracing through and adjusting pointers.
2179   ClassLoaderDataGraph::clear_claimed_marks();
2180 
2181   PSParallelCompact::AdjustPointerClosure oop_closure(cm);
2182 
2183   // General strong roots.
2184   Universe::oops_do(&oop_closure);
2185   JNIHandles::oops_do(&oop_closure);   // Global (strong) JNI handles
2186   Threads::oops_do(&oop_closure, NULL);
2187   ObjectSynchronizer::oops_do(&oop_closure);
2188   Management::oops_do(&oop_closure);
2189   JvmtiExport::oops_do(&oop_closure);
2190   SystemDictionary::oops_do(&oop_closure);
2191   CLDToOopClosure cld_closure(&oop_closure);
2192   ClassLoaderDataGraph::cld_do(&cld_closure);
2193 
2194   // Now adjust pointers in remaining weak roots.  (All of which should
2195   // have been cleared if they pointed to non-surviving objects.)
2196   WeakProcessor::oops_do(&oop_closure);
2197 
2198   CodeBlobToOopClosure adjust_from_blobs(&oop_closure, CodeBlobToOopClosure::FixRelocations);
2199   CodeCache::blobs_do(&adjust_from_blobs);
2200   AOTLoader::oops_do(&oop_closure);
2201   StringTable::oops_do(&oop_closure);
2202   ref_processor()->weak_oops_do(&oop_closure);
2203   // Roots were visited so references into the young gen in roots
2204   // may have been scanned.  Process them also.
2205   // Should the reference processor have a span that excludes
2206   // young gen objects?
2207   PSScavenge::reference_processor()->weak_oops_do(&oop_closure);
2208 }
2209 
2210 // Helper class to print 8 region numbers per line and then print the total at the end.
2211 class FillableRegionLogger : public StackObj {
2212 private:
2213   Log(gc, compaction) log;
2214   static const int LineLength = 8;
2215   size_t _regions[LineLength];
2216   int _next_index;
2217   bool _enabled;
2218   size_t _total_regions;
2219 public:
2220   FillableRegionLogger() : _next_index(0), _enabled(log_develop_is_enabled(Trace, gc, compaction)), _total_regions(0) { }
2221   ~FillableRegionLogger() {
2222     log.trace(SIZE_FORMAT " initially fillable regions", _total_regions);
2223   }
2224 
2225   void print_line() {
2226     if (!_enabled || _next_index == 0) {
2227       return;
2228     }
2229     FormatBuffer<> line("Fillable: ");
2230     for (int i = 0; i < _next_index; i++) {
2231       line.append(" " SIZE_FORMAT_W(7), _regions[i]);
2232     }
2233     log.trace("%s", line.buffer());
2234     _next_index = 0;
2235   }
2236 
2237   void handle(size_t region) {
2238     if (!_enabled) {
2239       return;
2240     }
2241     _regions[_next_index++] = region;
2242     if (_next_index == LineLength) {
2243       print_line();
2244     }
2245     _total_regions++;
2246   }
2247 };
2248 
2249 void PSParallelCompact::prepare_region_draining_tasks(GCTaskQueue* q,
2250                                                       uint parallel_gc_threads)
2251 {
2252   GCTraceTime(Trace, gc, phases) tm("Drain Task Setup", &_gc_timer);
2253 
2254   // Find the threads that are active
2255   unsigned int which = 0;
2256 
2257   // Find all regions that are available (can be filled immediately) and
2258   // distribute them to the thread stacks.  The iteration is done in reverse
2259   // order (high to low) so the regions will be removed in ascending order.
2260 
2261   const ParallelCompactData& sd = PSParallelCompact::summary_data();
2262 
2263   which = 0;
2264   // id + 1 is used to test termination so unsigned  can
2265   // be used with an old_space_id == 0.
2266   FillableRegionLogger region_logger;
2267   for (unsigned int id = to_space_id; id + 1 > old_space_id; --id) {
2268     SpaceInfo* const space_info = _space_info + id;
2269     MutableSpace* const space = space_info->space();
2270     HeapWord* const new_top = space_info->new_top();
2271 
2272     const size_t beg_region = sd.addr_to_region_idx(space_info->dense_prefix());
2273     const size_t end_region =
2274       sd.addr_to_region_idx(sd.region_align_up(new_top));
2275 
2276     for (size_t cur = end_region - 1; cur + 1 > beg_region; --cur) {
2277       if (sd.region(cur)->claim_unsafe()) {
2278         ParCompactionManager* cm = ParCompactionManager::manager_array(which);
2279         cm->region_stack()->push(cur);
2280         region_logger.handle(cur);
2281         // Assign regions to tasks in round-robin fashion.
2282         if (++which == parallel_gc_threads) {
2283           which = 0;
2284         }
2285       }
2286     }
2287     region_logger.print_line();
2288   }
2289 }
2290 
2291 #define PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING 4
2292 
2293 void PSParallelCompact::enqueue_dense_prefix_tasks(GCTaskQueue* q,
2294                                                     uint parallel_gc_threads) {
2295   GCTraceTime(Trace, gc, phases) tm("Dense Prefix Task Setup", &_gc_timer);
2296 
2297   ParallelCompactData& sd = PSParallelCompact::summary_data();
2298 
2299   // Iterate over all the spaces adding tasks for updating
2300   // regions in the dense prefix.  Assume that 1 gc thread
2301   // will work on opening the gaps and the remaining gc threads
2302   // will work on the dense prefix.
2303   unsigned int space_id;
2304   for (space_id = old_space_id; space_id < last_space_id; ++ space_id) {
2305     HeapWord* const dense_prefix_end = _space_info[space_id].dense_prefix();
2306     const MutableSpace* const space = _space_info[space_id].space();
2307 
2308     if (dense_prefix_end == space->bottom()) {
2309       // There is no dense prefix for this space.
2310       continue;
2311     }
2312 
2313     // The dense prefix is before this region.
2314     size_t region_index_end_dense_prefix =
2315         sd.addr_to_region_idx(dense_prefix_end);
2316     RegionData* const dense_prefix_cp =
2317       sd.region(region_index_end_dense_prefix);
2318     assert(dense_prefix_end == space->end() ||
2319            dense_prefix_cp->available() ||
2320            dense_prefix_cp->claimed(),
2321            "The region after the dense prefix should always be ready to fill");
2322 
2323     size_t region_index_start = sd.addr_to_region_idx(space->bottom());
2324 
2325     // Is there dense prefix work?
2326     size_t total_dense_prefix_regions =
2327       region_index_end_dense_prefix - region_index_start;
2328     // How many regions of the dense prefix should be given to
2329     // each thread?
2330     if (total_dense_prefix_regions > 0) {
2331       uint tasks_for_dense_prefix = 1;
2332       if (total_dense_prefix_regions <=
2333           (parallel_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING)) {
2334         // Don't over partition.  This assumes that
2335         // PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING is a small integer value
2336         // so there are not many regions to process.
2337         tasks_for_dense_prefix = parallel_gc_threads;
2338       } else {
2339         // Over partition
2340         tasks_for_dense_prefix = parallel_gc_threads *
2341           PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING;
2342       }
2343       size_t regions_per_thread = total_dense_prefix_regions /
2344         tasks_for_dense_prefix;
2345       // Give each thread at least 1 region.
2346       if (regions_per_thread == 0) {
2347         regions_per_thread = 1;
2348       }
2349 
2350       for (uint k = 0; k < tasks_for_dense_prefix; k++) {
2351         if (region_index_start >= region_index_end_dense_prefix) {
2352           break;
2353         }
2354         // region_index_end is not processed
2355         size_t region_index_end = MIN2(region_index_start + regions_per_thread,
2356                                        region_index_end_dense_prefix);
2357         q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id),
2358                                              region_index_start,
2359                                              region_index_end));
2360         region_index_start = region_index_end;
2361       }
2362     }
2363     // This gets any part of the dense prefix that did not
2364     // fit evenly.
2365     if (region_index_start < region_index_end_dense_prefix) {
2366       q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id),
2367                                            region_index_start,
2368                                            region_index_end_dense_prefix));
2369     }
2370   }
2371 }
2372 
2373 void PSParallelCompact::enqueue_region_stealing_tasks(
2374                                      GCTaskQueue* q,
2375                                      ParallelTaskTerminator* terminator_ptr,
2376                                      uint parallel_gc_threads) {
2377   GCTraceTime(Trace, gc, phases) tm("Steal Task Setup", &_gc_timer);
2378 
2379   // Once a thread has drained it's stack, it should try to steal regions from
2380   // other threads.
2381   for (uint j = 0; j < parallel_gc_threads; j++) {
2382     q->enqueue(new CompactionWithStealingTask(terminator_ptr));
2383   }
2384 }
2385 
2386 #ifdef ASSERT
2387 // Write a histogram of the number of times the block table was filled for a
2388 // region.
2389 void PSParallelCompact::write_block_fill_histogram()
2390 {
2391   if (!log_develop_is_enabled(Trace, gc, compaction)) {
2392     return;
2393   }
2394 
2395   Log(gc, compaction) log;
2396   ResourceMark rm;
2397   LogStream ls(log.trace());
2398   outputStream* out = &ls;
2399 
2400   typedef ParallelCompactData::RegionData rd_t;
2401   ParallelCompactData& sd = summary_data();
2402 
2403   for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2404     MutableSpace* const spc = _space_info[id].space();
2405     if (spc->bottom() != spc->top()) {
2406       const rd_t* const beg = sd.addr_to_region_ptr(spc->bottom());
2407       HeapWord* const top_aligned_up = sd.region_align_up(spc->top());
2408       const rd_t* const end = sd.addr_to_region_ptr(top_aligned_up);
2409 
2410       size_t histo[5] = { 0, 0, 0, 0, 0 };
2411       const size_t histo_len = sizeof(histo) / sizeof(size_t);
2412       const size_t region_cnt = pointer_delta(end, beg, sizeof(rd_t));
2413 
2414       for (const rd_t* cur = beg; cur < end; ++cur) {
2415         ++histo[MIN2(cur->blocks_filled_count(), histo_len - 1)];
2416       }
2417       out->print("Block fill histogram: %u %-4s" SIZE_FORMAT_W(5), id, space_names[id], region_cnt);
2418       for (size_t i = 0; i < histo_len; ++i) {
2419         out->print(" " SIZE_FORMAT_W(5) " %5.1f%%",
2420                    histo[i], 100.0 * histo[i] / region_cnt);
2421       }
2422       out->cr();
2423     }
2424   }
2425 }
2426 #endif // #ifdef ASSERT
2427 
2428 void PSParallelCompact::compact() {
2429   GCTraceTime(Info, gc, phases) tm("Compaction Phase", &_gc_timer);
2430 
2431   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
2432   PSOldGen* old_gen = heap->old_gen();
2433   old_gen->start_array()->reset();
2434   uint parallel_gc_threads = heap->gc_task_manager()->workers();
2435   uint active_gc_threads = heap->gc_task_manager()->active_workers();
2436   TaskQueueSetSuper* qset = ParCompactionManager::region_array();
2437   ParallelTaskTerminator terminator(active_gc_threads, qset);
2438 
2439   GCTaskQueue* q = GCTaskQueue::create();
2440   prepare_region_draining_tasks(q, active_gc_threads);
2441   enqueue_dense_prefix_tasks(q, active_gc_threads);
2442   enqueue_region_stealing_tasks(q, &terminator, active_gc_threads);
2443 
2444   {
2445     GCTraceTime(Trace, gc, phases) tm("Par Compact", &_gc_timer);
2446 
2447     gc_task_manager()->execute_and_wait(q);
2448 
2449 #ifdef  ASSERT
2450     // Verify that all regions have been processed before the deferred updates.
2451     for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2452       verify_complete(SpaceId(id));
2453     }
2454 #endif
2455   }
2456 
2457   {
2458     // Update the deferred objects, if any.  Any compaction manager can be used.
2459     GCTraceTime(Trace, gc, phases) tm("Deferred Updates", &_gc_timer);
2460     ParCompactionManager* cm = ParCompactionManager::manager_array(0);
2461     for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2462       update_deferred_objects(cm, SpaceId(id));
2463     }
2464   }
2465 
2466   DEBUG_ONLY(write_block_fill_histogram());
2467 }
2468 
2469 #ifdef  ASSERT
2470 void PSParallelCompact::verify_complete(SpaceId space_id) {
2471   // All Regions between space bottom() to new_top() should be marked as filled
2472   // and all Regions between new_top() and top() should be available (i.e.,
2473   // should have been emptied).
2474   ParallelCompactData& sd = summary_data();
2475   SpaceInfo si = _space_info[space_id];
2476   HeapWord* new_top_addr = sd.region_align_up(si.new_top());
2477   HeapWord* old_top_addr = sd.region_align_up(si.space()->top());
2478   const size_t beg_region = sd.addr_to_region_idx(si.space()->bottom());
2479   const size_t new_top_region = sd.addr_to_region_idx(new_top_addr);
2480   const size_t old_top_region = sd.addr_to_region_idx(old_top_addr);
2481 
2482   bool issued_a_warning = false;
2483 
2484   size_t cur_region;
2485   for (cur_region = beg_region; cur_region < new_top_region; ++cur_region) {
2486     const RegionData* const c = sd.region(cur_region);
2487     if (!c->completed()) {
2488       log_warning(gc)("region " SIZE_FORMAT " not filled: destination_count=%u",
2489                       cur_region, c->destination_count());
2490       issued_a_warning = true;
2491     }
2492   }
2493 
2494   for (cur_region = new_top_region; cur_region < old_top_region; ++cur_region) {
2495     const RegionData* const c = sd.region(cur_region);
2496     if (!c->available()) {
2497       log_warning(gc)("region " SIZE_FORMAT " not empty: destination_count=%u",
2498                       cur_region, c->destination_count());
2499       issued_a_warning = true;
2500     }
2501   }
2502 
2503   if (issued_a_warning) {
2504     print_region_ranges();
2505   }
2506 }
2507 #endif  // #ifdef ASSERT
2508 
2509 inline void UpdateOnlyClosure::do_addr(HeapWord* addr) {
2510   _start_array->allocate_block(addr);
2511   compaction_manager()->update_contents(oop(addr));
2512 }
2513 
2514 // Update interior oops in the ranges of regions [beg_region, end_region).
2515 void
2516 PSParallelCompact::update_and_deadwood_in_dense_prefix(ParCompactionManager* cm,
2517                                                        SpaceId space_id,
2518                                                        size_t beg_region,
2519                                                        size_t end_region) {
2520   ParallelCompactData& sd = summary_data();
2521   ParMarkBitMap* const mbm = mark_bitmap();
2522 
2523   HeapWord* beg_addr = sd.region_to_addr(beg_region);
2524   HeapWord* const end_addr = sd.region_to_addr(end_region);
2525   assert(beg_region <= end_region, "bad region range");
2526   assert(end_addr <= dense_prefix(space_id), "not in the dense prefix");
2527 
2528 #ifdef  ASSERT
2529   // Claim the regions to avoid triggering an assert when they are marked as
2530   // filled.
2531   for (size_t claim_region = beg_region; claim_region < end_region; ++claim_region) {
2532     assert(sd.region(claim_region)->claim_unsafe(), "claim() failed");
2533   }
2534 #endif  // #ifdef ASSERT
2535 
2536   if (beg_addr != space(space_id)->bottom()) {
2537     // Find the first live object or block of dead space that *starts* in this
2538     // range of regions.  If a partial object crosses onto the region, skip it;
2539     // it will be marked for 'deferred update' when the object head is
2540     // processed.  If dead space crosses onto the region, it is also skipped; it
2541     // will be filled when the prior region is processed.  If neither of those
2542     // apply, the first word in the region is the start of a live object or dead
2543     // space.
2544     assert(beg_addr > space(space_id)->bottom(), "sanity");
2545     const RegionData* const cp = sd.region(beg_region);
2546     if (cp->partial_obj_size() != 0) {
2547       beg_addr = sd.partial_obj_end(beg_region);
2548     } else if (dead_space_crosses_boundary(cp, mbm->addr_to_bit(beg_addr))) {
2549       beg_addr = mbm->find_obj_beg(beg_addr, end_addr);
2550     }
2551   }
2552 
2553   if (beg_addr < end_addr) {
2554     // A live object or block of dead space starts in this range of Regions.
2555      HeapWord* const dense_prefix_end = dense_prefix(space_id);
2556 
2557     // Create closures and iterate.
2558     UpdateOnlyClosure update_closure(mbm, cm, space_id);
2559     FillClosure fill_closure(cm, space_id);
2560     ParMarkBitMap::IterationStatus status;
2561     status = mbm->iterate(&update_closure, &fill_closure, beg_addr, end_addr,
2562                           dense_prefix_end);
2563     if (status == ParMarkBitMap::incomplete) {
2564       update_closure.do_addr(update_closure.source());
2565     }
2566   }
2567 
2568   // Mark the regions as filled.
2569   RegionData* const beg_cp = sd.region(beg_region);
2570   RegionData* const end_cp = sd.region(end_region);
2571   for (RegionData* cp = beg_cp; cp < end_cp; ++cp) {
2572     cp->set_completed();
2573   }
2574 }
2575 
2576 // Return the SpaceId for the space containing addr.  If addr is not in the
2577 // heap, last_space_id is returned.  In debug mode it expects the address to be
2578 // in the heap and asserts such.
2579 PSParallelCompact::SpaceId PSParallelCompact::space_id(HeapWord* addr) {
2580   assert(ParallelScavengeHeap::heap()->is_in_reserved(addr), "addr not in the heap");
2581 
2582   for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2583     if (_space_info[id].space()->contains(addr)) {
2584       return SpaceId(id);
2585     }
2586   }
2587 
2588   assert(false, "no space contains the addr");
2589   return last_space_id;
2590 }
2591 
2592 void PSParallelCompact::update_deferred_objects(ParCompactionManager* cm,
2593                                                 SpaceId id) {
2594   assert(id < last_space_id, "bad space id");
2595 
2596   ParallelCompactData& sd = summary_data();
2597   const SpaceInfo* const space_info = _space_info + id;
2598   ObjectStartArray* const start_array = space_info->start_array();
2599 
2600   const MutableSpace* const space = space_info->space();
2601   assert(space_info->dense_prefix() >= space->bottom(), "dense_prefix not set");
2602   HeapWord* const beg_addr = space_info->dense_prefix();
2603   HeapWord* const end_addr = sd.region_align_up(space_info->new_top());
2604 
2605   const RegionData* const beg_region = sd.addr_to_region_ptr(beg_addr);
2606   const RegionData* const end_region = sd.addr_to_region_ptr(end_addr);
2607   const RegionData* cur_region;
2608   for (cur_region = beg_region; cur_region < end_region; ++cur_region) {
2609     HeapWord* const addr = cur_region->deferred_obj_addr();
2610     if (addr != NULL) {
2611       if (start_array != NULL) {
2612         start_array->allocate_block(addr);
2613       }
2614       cm->update_contents(oop(addr));
2615       assert(oopDesc::is_oop_or_null(oop(addr)), "Expected an oop or NULL at " PTR_FORMAT, p2i(oop(addr)));
2616     }
2617   }
2618 }
2619 
2620 // Skip over count live words starting from beg, and return the address of the
2621 // next live word.  Unless marked, the word corresponding to beg is assumed to
2622 // be dead.  Callers must either ensure beg does not correspond to the middle of
2623 // an object, or account for those live words in some other way.  Callers must
2624 // also ensure that there are enough live words in the range [beg, end) to skip.
2625 HeapWord*
2626 PSParallelCompact::skip_live_words(HeapWord* beg, HeapWord* end, size_t count)
2627 {
2628   assert(count > 0, "sanity");
2629 
2630   ParMarkBitMap* m = mark_bitmap();
2631   idx_t bits_to_skip = m->words_to_bits(count);
2632   idx_t cur_beg = m->addr_to_bit(beg);
2633   const idx_t search_end = BitMap::word_align_up(m->addr_to_bit(end));
2634 
2635   do {
2636     cur_beg = m->find_obj_beg(cur_beg, search_end);
2637     idx_t cur_end = m->find_obj_end(cur_beg, search_end);
2638     const size_t obj_bits = cur_end - cur_beg + 1;
2639     if (obj_bits > bits_to_skip) {
2640       return m->bit_to_addr(cur_beg + bits_to_skip);
2641     }
2642     bits_to_skip -= obj_bits;
2643     cur_beg = cur_end + 1;
2644   } while (bits_to_skip > 0);
2645 
2646   // Skipping the desired number of words landed just past the end of an object.
2647   // Find the start of the next object.
2648   cur_beg = m->find_obj_beg(cur_beg, search_end);
2649   assert(cur_beg < m->addr_to_bit(end), "not enough live words to skip");
2650   return m->bit_to_addr(cur_beg);
2651 }
2652 
2653 HeapWord* PSParallelCompact::first_src_addr(HeapWord* const dest_addr,
2654                                             SpaceId src_space_id,
2655                                             size_t src_region_idx)
2656 {
2657   assert(summary_data().is_region_aligned(dest_addr), "not aligned");
2658 
2659   const SplitInfo& split_info = _space_info[src_space_id].split_info();
2660   if (split_info.dest_region_addr() == dest_addr) {
2661     // The partial object ending at the split point contains the first word to
2662     // be copied to dest_addr.
2663     return split_info.first_src_addr();
2664   }
2665 
2666   const ParallelCompactData& sd = summary_data();
2667   ParMarkBitMap* const bitmap = mark_bitmap();
2668   const size_t RegionSize = ParallelCompactData::RegionSize;
2669 
2670   assert(sd.is_region_aligned(dest_addr), "not aligned");
2671   const RegionData* const src_region_ptr = sd.region(src_region_idx);
2672   const size_t partial_obj_size = src_region_ptr->partial_obj_size();
2673   HeapWord* const src_region_destination = src_region_ptr->destination();
2674 
2675   assert(dest_addr >= src_region_destination, "wrong src region");
2676   assert(src_region_ptr->data_size() > 0, "src region cannot be empty");
2677 
2678   HeapWord* const src_region_beg = sd.region_to_addr(src_region_idx);
2679   HeapWord* const src_region_end = src_region_beg + RegionSize;
2680 
2681   HeapWord* addr = src_region_beg;
2682   if (dest_addr == src_region_destination) {
2683     // Return the first live word in the source region.
2684     if (partial_obj_size == 0) {
2685       addr = bitmap->find_obj_beg(addr, src_region_end);
2686       assert(addr < src_region_end, "no objects start in src region");
2687     }
2688     return addr;
2689   }
2690 
2691   // Must skip some live data.
2692   size_t words_to_skip = dest_addr - src_region_destination;
2693   assert(src_region_ptr->data_size() > words_to_skip, "wrong src region");
2694 
2695   if (partial_obj_size >= words_to_skip) {
2696     // All the live words to skip are part of the partial object.
2697     addr += words_to_skip;
2698     if (partial_obj_size == words_to_skip) {
2699       // Find the first live word past the partial object.
2700       addr = bitmap->find_obj_beg(addr, src_region_end);
2701       assert(addr < src_region_end, "wrong src region");
2702     }
2703     return addr;
2704   }
2705 
2706   // Skip over the partial object (if any).
2707   if (partial_obj_size != 0) {
2708     words_to_skip -= partial_obj_size;
2709     addr += partial_obj_size;
2710   }
2711 
2712   // Skip over live words due to objects that start in the region.
2713   addr = skip_live_words(addr, src_region_end, words_to_skip);
2714   assert(addr < src_region_end, "wrong src region");
2715   return addr;
2716 }
2717 
2718 void PSParallelCompact::decrement_destination_counts(ParCompactionManager* cm,
2719                                                      SpaceId src_space_id,
2720                                                      size_t beg_region,
2721                                                      HeapWord* end_addr)
2722 {
2723   ParallelCompactData& sd = summary_data();
2724 
2725 #ifdef ASSERT
2726   MutableSpace* const src_space = _space_info[src_space_id].space();
2727   HeapWord* const beg_addr = sd.region_to_addr(beg_region);
2728   assert(src_space->contains(beg_addr) || beg_addr == src_space->end(),
2729          "src_space_id does not match beg_addr");
2730   assert(src_space->contains(end_addr) || end_addr == src_space->end(),
2731          "src_space_id does not match end_addr");
2732 #endif // #ifdef ASSERT
2733 
2734   RegionData* const beg = sd.region(beg_region);
2735   RegionData* const end = sd.addr_to_region_ptr(sd.region_align_up(end_addr));
2736 
2737   // Regions up to new_top() are enqueued if they become available.
2738   HeapWord* const new_top = _space_info[src_space_id].new_top();
2739   RegionData* const enqueue_end =
2740     sd.addr_to_region_ptr(sd.region_align_up(new_top));
2741 
2742   for (RegionData* cur = beg; cur < end; ++cur) {
2743     assert(cur->data_size() > 0, "region must have live data");
2744     cur->decrement_destination_count();
2745     if (cur < enqueue_end && cur->available() && cur->claim()) {
2746       cm->push_region(sd.region(cur));
2747     }
2748   }
2749 }
2750 
2751 size_t PSParallelCompact::next_src_region(MoveAndUpdateClosure& closure,
2752                                           SpaceId& src_space_id,
2753                                           HeapWord*& src_space_top,
2754                                           HeapWord* end_addr)
2755 {
2756   typedef ParallelCompactData::RegionData RegionData;
2757 
2758   ParallelCompactData& sd = PSParallelCompact::summary_data();
2759   const size_t region_size = ParallelCompactData::RegionSize;
2760 
2761   size_t src_region_idx = 0;
2762 
2763   // Skip empty regions (if any) up to the top of the space.
2764   HeapWord* const src_aligned_up = sd.region_align_up(end_addr);
2765   RegionData* src_region_ptr = sd.addr_to_region_ptr(src_aligned_up);
2766   HeapWord* const top_aligned_up = sd.region_align_up(src_space_top);
2767   const RegionData* const top_region_ptr =
2768     sd.addr_to_region_ptr(top_aligned_up);
2769   while (src_region_ptr < top_region_ptr && src_region_ptr->data_size() == 0) {
2770     ++src_region_ptr;
2771   }
2772 
2773   if (src_region_ptr < top_region_ptr) {
2774     // The next source region is in the current space.  Update src_region_idx
2775     // and the source address to match src_region_ptr.
2776     src_region_idx = sd.region(src_region_ptr);
2777     HeapWord* const src_region_addr = sd.region_to_addr(src_region_idx);
2778     if (src_region_addr > closure.source()) {
2779       closure.set_source(src_region_addr);
2780     }
2781     return src_region_idx;
2782   }
2783 
2784   // Switch to a new source space and find the first non-empty region.
2785   unsigned int space_id = src_space_id + 1;
2786   assert(space_id < last_space_id, "not enough spaces");
2787 
2788   HeapWord* const destination = closure.destination();
2789 
2790   do {
2791     MutableSpace* space = _space_info[space_id].space();
2792     HeapWord* const bottom = space->bottom();
2793     const RegionData* const bottom_cp = sd.addr_to_region_ptr(bottom);
2794 
2795     // Iterate over the spaces that do not compact into themselves.
2796     if (bottom_cp->destination() != bottom) {
2797       HeapWord* const top_aligned_up = sd.region_align_up(space->top());
2798       const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
2799 
2800       for (const RegionData* src_cp = bottom_cp; src_cp < top_cp; ++src_cp) {
2801         if (src_cp->live_obj_size() > 0) {
2802           // Found it.
2803           assert(src_cp->destination() == destination,
2804                  "first live obj in the space must match the destination");
2805           assert(src_cp->partial_obj_size() == 0,
2806                  "a space cannot begin with a partial obj");
2807 
2808           src_space_id = SpaceId(space_id);
2809           src_space_top = space->top();
2810           const size_t src_region_idx = sd.region(src_cp);
2811           closure.set_source(sd.region_to_addr(src_region_idx));
2812           return src_region_idx;
2813         } else {
2814           assert(src_cp->data_size() == 0, "sanity");
2815         }
2816       }
2817     }
2818   } while (++space_id < last_space_id);
2819 
2820   assert(false, "no source region was found");
2821   return 0;
2822 }
2823 
2824 void PSParallelCompact::fill_region(ParCompactionManager* cm, size_t region_idx)
2825 {
2826   typedef ParMarkBitMap::IterationStatus IterationStatus;
2827   const size_t RegionSize = ParallelCompactData::RegionSize;
2828   ParMarkBitMap* const bitmap = mark_bitmap();
2829   ParallelCompactData& sd = summary_data();
2830   RegionData* const region_ptr = sd.region(region_idx);
2831 
2832   // Get the items needed to construct the closure.
2833   HeapWord* dest_addr = sd.region_to_addr(region_idx);
2834   SpaceId dest_space_id = space_id(dest_addr);
2835   ObjectStartArray* start_array = _space_info[dest_space_id].start_array();
2836   HeapWord* new_top = _space_info[dest_space_id].new_top();
2837   assert(dest_addr < new_top, "sanity");
2838   const size_t words = MIN2(pointer_delta(new_top, dest_addr), RegionSize);
2839 
2840   // Get the source region and related info.
2841   size_t src_region_idx = region_ptr->source_region();
2842   SpaceId src_space_id = space_id(sd.region_to_addr(src_region_idx));
2843   HeapWord* src_space_top = _space_info[src_space_id].space()->top();
2844 
2845   MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words);
2846   closure.set_source(first_src_addr(dest_addr, src_space_id, src_region_idx));
2847 
2848   // Adjust src_region_idx to prepare for decrementing destination counts (the
2849   // destination count is not decremented when a region is copied to itself).
2850   if (src_region_idx == region_idx) {
2851     src_region_idx += 1;
2852   }
2853 
2854   if (bitmap->is_unmarked(closure.source())) {
2855     // The first source word is in the middle of an object; copy the remainder
2856     // of the object or as much as will fit.  The fact that pointer updates were
2857     // deferred will be noted when the object header is processed.
2858     HeapWord* const old_src_addr = closure.source();
2859     closure.copy_partial_obj();
2860     if (closure.is_full()) {
2861       decrement_destination_counts(cm, src_space_id, src_region_idx,
2862                                    closure.source());
2863       region_ptr->set_deferred_obj_addr(NULL);
2864       region_ptr->set_completed();
2865       return;
2866     }
2867 
2868     HeapWord* const end_addr = sd.region_align_down(closure.source());
2869     if (sd.region_align_down(old_src_addr) != end_addr) {
2870       // The partial object was copied from more than one source region.
2871       decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
2872 
2873       // Move to the next source region, possibly switching spaces as well.  All
2874       // args except end_addr may be modified.
2875       src_region_idx = next_src_region(closure, src_space_id, src_space_top,
2876                                        end_addr);
2877     }
2878   }
2879 
2880   do {
2881     HeapWord* const cur_addr = closure.source();
2882     HeapWord* const end_addr = MIN2(sd.region_align_up(cur_addr + 1),
2883                                     src_space_top);
2884     IterationStatus status = bitmap->iterate(&closure, cur_addr, end_addr);
2885 
2886     if (status == ParMarkBitMap::incomplete) {
2887       // The last obj that starts in the source region does not end in the
2888       // region.
2889       assert(closure.source() < end_addr, "sanity");
2890       HeapWord* const obj_beg = closure.source();
2891       HeapWord* const range_end = MIN2(obj_beg + closure.words_remaining(),
2892                                        src_space_top);
2893       HeapWord* const obj_end = bitmap->find_obj_end(obj_beg, range_end);
2894       if (obj_end < range_end) {
2895         // The end was found; the entire object will fit.
2896         status = closure.do_addr(obj_beg, bitmap->obj_size(obj_beg, obj_end));
2897         assert(status != ParMarkBitMap::would_overflow, "sanity");
2898       } else {
2899         // The end was not found; the object will not fit.
2900         assert(range_end < src_space_top, "obj cannot cross space boundary");
2901         status = ParMarkBitMap::would_overflow;
2902       }
2903     }
2904 
2905     if (status == ParMarkBitMap::would_overflow) {
2906       // The last object did not fit.  Note that interior oop updates were
2907       // deferred, then copy enough of the object to fill the region.
2908       region_ptr->set_deferred_obj_addr(closure.destination());
2909       status = closure.copy_until_full(); // copies from closure.source()
2910 
2911       decrement_destination_counts(cm, src_space_id, src_region_idx,
2912                                    closure.source());
2913       region_ptr->set_completed();
2914       return;
2915     }
2916 
2917     if (status == ParMarkBitMap::full) {
2918       decrement_destination_counts(cm, src_space_id, src_region_idx,
2919                                    closure.source());
2920       region_ptr->set_deferred_obj_addr(NULL);
2921       region_ptr->set_completed();
2922       return;
2923     }
2924 
2925     decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
2926 
2927     // Move to the next source region, possibly switching spaces as well.  All
2928     // args except end_addr may be modified.
2929     src_region_idx = next_src_region(closure, src_space_id, src_space_top,
2930                                      end_addr);
2931   } while (true);
2932 }
2933 
2934 void PSParallelCompact::fill_blocks(size_t region_idx)
2935 {
2936   // Fill in the block table elements for the specified region.  Each block
2937   // table element holds the number of live words in the region that are to the
2938   // left of the first object that starts in the block.  Thus only blocks in
2939   // which an object starts need to be filled.
2940   //
2941   // The algorithm scans the section of the bitmap that corresponds to the
2942   // region, keeping a running total of the live words.  When an object start is
2943   // found, if it's the first to start in the block that contains it, the
2944   // current total is written to the block table element.
2945   const size_t Log2BlockSize = ParallelCompactData::Log2BlockSize;
2946   const size_t Log2RegionSize = ParallelCompactData::Log2RegionSize;
2947   const size_t RegionSize = ParallelCompactData::RegionSize;
2948 
2949   ParallelCompactData& sd = summary_data();
2950   const size_t partial_obj_size = sd.region(region_idx)->partial_obj_size();
2951   if (partial_obj_size >= RegionSize) {
2952     return; // No objects start in this region.
2953   }
2954 
2955   // Ensure the first loop iteration decides that the block has changed.
2956   size_t cur_block = sd.block_count();
2957 
2958   const ParMarkBitMap* const bitmap = mark_bitmap();
2959 
2960   const size_t Log2BitsPerBlock = Log2BlockSize - LogMinObjAlignment;
2961   assert((size_t)1 << Log2BitsPerBlock ==
2962          bitmap->words_to_bits(ParallelCompactData::BlockSize), "sanity");
2963 
2964   size_t beg_bit = bitmap->words_to_bits(region_idx << Log2RegionSize);
2965   const size_t range_end = beg_bit + bitmap->words_to_bits(RegionSize);
2966   size_t live_bits = bitmap->words_to_bits(partial_obj_size);
2967   beg_bit = bitmap->find_obj_beg(beg_bit + live_bits, range_end);
2968   while (beg_bit < range_end) {
2969     const size_t new_block = beg_bit >> Log2BitsPerBlock;
2970     if (new_block != cur_block) {
2971       cur_block = new_block;
2972       sd.block(cur_block)->set_offset(bitmap->bits_to_words(live_bits));
2973     }
2974 
2975     const size_t end_bit = bitmap->find_obj_end(beg_bit, range_end);
2976     if (end_bit < range_end - 1) {
2977       live_bits += end_bit - beg_bit + 1;
2978       beg_bit = bitmap->find_obj_beg(end_bit + 1, range_end);
2979     } else {
2980       return;
2981     }
2982   }
2983 }
2984 
2985 void
2986 PSParallelCompact::move_and_update(ParCompactionManager* cm, SpaceId space_id) {
2987   const MutableSpace* sp = space(space_id);
2988   if (sp->is_empty()) {
2989     return;
2990   }
2991 
2992   ParallelCompactData& sd = PSParallelCompact::summary_data();
2993   ParMarkBitMap* const bitmap = mark_bitmap();
2994   HeapWord* const dp_addr = dense_prefix(space_id);
2995   HeapWord* beg_addr = sp->bottom();
2996   HeapWord* end_addr = sp->top();
2997 
2998   assert(beg_addr <= dp_addr && dp_addr <= end_addr, "bad dense prefix");
2999 
3000   const size_t beg_region = sd.addr_to_region_idx(beg_addr);
3001   const size_t dp_region = sd.addr_to_region_idx(dp_addr);
3002   if (beg_region < dp_region) {
3003     update_and_deadwood_in_dense_prefix(cm, space_id, beg_region, dp_region);
3004   }
3005 
3006   // The destination of the first live object that starts in the region is one
3007   // past the end of the partial object entering the region (if any).
3008   HeapWord* const dest_addr = sd.partial_obj_end(dp_region);
3009   HeapWord* const new_top = _space_info[space_id].new_top();
3010   assert(new_top >= dest_addr, "bad new_top value");
3011   const size_t words = pointer_delta(new_top, dest_addr);
3012 
3013   if (words > 0) {
3014     ObjectStartArray* start_array = _space_info[space_id].start_array();
3015     MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words);
3016 
3017     ParMarkBitMap::IterationStatus status;
3018     status = bitmap->iterate(&closure, dest_addr, end_addr);
3019     assert(status == ParMarkBitMap::full, "iteration not complete");
3020     assert(bitmap->find_obj_beg(closure.source(), end_addr) == end_addr,
3021            "live objects skipped because closure is full");
3022   }
3023 }
3024 
3025 jlong PSParallelCompact::millis_since_last_gc() {
3026   // We need a monotonically non-decreasing time in ms but
3027   // os::javaTimeMillis() does not guarantee monotonicity.
3028   jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
3029   jlong ret_val = now - _time_of_last_gc;
3030   // XXX See note in genCollectedHeap::millis_since_last_gc().
3031   if (ret_val < 0) {
3032     NOT_PRODUCT(log_warning(gc)("time warp: " JLONG_FORMAT, ret_val);)
3033     return 0;
3034   }
3035   return ret_val;
3036 }
3037 
3038 void PSParallelCompact::reset_millis_since_last_gc() {
3039   // We need a monotonically non-decreasing time in ms but
3040   // os::javaTimeMillis() does not guarantee monotonicity.
3041   _time_of_last_gc = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
3042 }
3043 
3044 ParMarkBitMap::IterationStatus MoveAndUpdateClosure::copy_until_full()
3045 {
3046   if (source() != destination()) {
3047     DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3048     Copy::aligned_conjoint_words(source(), destination(), words_remaining());
3049   }
3050   update_state(words_remaining());
3051   assert(is_full(), "sanity");
3052   return ParMarkBitMap::full;
3053 }
3054 
3055 void MoveAndUpdateClosure::copy_partial_obj()
3056 {
3057   size_t words = words_remaining();
3058 
3059   HeapWord* const range_end = MIN2(source() + words, bitmap()->region_end());
3060   HeapWord* const end_addr = bitmap()->find_obj_end(source(), range_end);
3061   if (end_addr < range_end) {
3062     words = bitmap()->obj_size(source(), end_addr);
3063   }
3064 
3065   // This test is necessary; if omitted, the pointer updates to a partial object
3066   // that crosses the dense prefix boundary could be overwritten.
3067   if (source() != destination()) {
3068     DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3069     Copy::aligned_conjoint_words(source(), destination(), words);
3070   }
3071   update_state(words);
3072 }
3073 
3074 void InstanceKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) {
3075   PSParallelCompact::AdjustPointerClosure closure(cm);
3076   if (UseCompressedOops) {
3077     oop_oop_iterate_oop_maps<narrowOop>(obj, &closure);
3078   } else {
3079     oop_oop_iterate_oop_maps<oop>(obj, &closure);
3080   }
3081 }
3082 
3083 void InstanceMirrorKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) {
3084   InstanceKlass::oop_pc_update_pointers(obj, cm);
3085 
3086   PSParallelCompact::AdjustPointerClosure closure(cm);
3087   if (UseCompressedOops) {
3088     oop_oop_iterate_statics<narrowOop>(obj, &closure);
3089   } else {
3090     oop_oop_iterate_statics<oop>(obj, &closure);
3091   }
3092 }
3093 
3094 void InstanceClassLoaderKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) {
3095   InstanceKlass::oop_pc_update_pointers(obj, cm);
3096 }
3097 
3098 #ifdef ASSERT
3099 template <class T> static void trace_reference_gc(const char *s, oop obj,
3100                                                   T* referent_addr,
3101                                                   T* discovered_addr) {
3102   log_develop_trace(gc, ref)("%s obj " PTR_FORMAT, s, p2i(obj));
3103   log_develop_trace(gc, ref)("     referent_addr/* " PTR_FORMAT " / " PTR_FORMAT,
3104                              p2i(referent_addr), referent_addr ? p2i((oop)RawAccess<>::oop_load(referent_addr)) : NULL);
3105   log_develop_trace(gc, ref)("     discovered_addr/* " PTR_FORMAT " / " PTR_FORMAT,
3106                              p2i(discovered_addr), discovered_addr ? p2i((oop)RawAccess<>::oop_load(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_raw(obj);
3113   PSParallelCompact::adjust_pointer(referent_addr, cm);
3114   T* discovered_addr = (T*)java_lang_ref_Reference::discovered_addr_raw(obj);
3115   PSParallelCompact::adjust_pointer(discovered_addr, cm);
3116   debug_only(trace_reference_gc("InstanceRefKlass::oop_update_ptrs", obj,
3117                                 referent_addr, discovered_addr);)
3118 }
3119 
3120 void InstanceRefKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) {
3121   InstanceKlass::oop_pc_update_pointers(obj, cm);
3122 
3123   if (UseCompressedOops) {
3124     oop_pc_update_pointers_specialized<narrowOop>(obj, cm);
3125   } else {
3126     oop_pc_update_pointers_specialized<oop>(obj, cm);
3127   }
3128 }
3129 
3130 void ObjArrayKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) {
3131   assert(obj->is_objArray(), "obj must be obj array");
3132   PSParallelCompact::AdjustPointerClosure closure(cm);
3133   if (UseCompressedOops) {
3134     oop_oop_iterate_elements<narrowOop>(objArrayOop(obj), &closure);
3135   } else {
3136     oop_oop_iterate_elements<oop>(objArrayOop(obj), &closure);
3137   }
3138 }
3139 
3140 void TypeArrayKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) {
3141   assert(obj->is_typeArray(),"must be a type array");
3142 }
3143 
3144 ParMarkBitMapClosure::IterationStatus
3145 MoveAndUpdateClosure::do_addr(HeapWord* addr, size_t words) {
3146   assert(destination() != NULL, "sanity");
3147   assert(bitmap()->obj_size(addr) == words, "bad size");
3148 
3149   _source = addr;
3150   assert(PSParallelCompact::summary_data().calc_new_pointer(source(), compaction_manager()) ==
3151          destination(), "wrong destination");
3152 
3153   if (words > words_remaining()) {
3154     return ParMarkBitMap::would_overflow;
3155   }
3156 
3157   // The start_array must be updated even if the object is not moving.
3158   if (_start_array != NULL) {
3159     _start_array->allocate_block(destination());
3160   }
3161 
3162   if (destination() != source()) {
3163     DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3164     Copy::aligned_conjoint_words(source(), destination(), words);
3165   }
3166 
3167   oop moved_oop = (oop) destination();
3168   compaction_manager()->update_contents(moved_oop);
3169   assert(oopDesc::is_oop_or_null(moved_oop), "Expected an oop or NULL at " PTR_FORMAT, p2i(moved_oop));
3170 
3171   update_state(words);
3172   assert(destination() == (HeapWord*)moved_oop + moved_oop->size(), "sanity");
3173   return is_full() ? ParMarkBitMap::full : ParMarkBitMap::incomplete;
3174 }
3175 
3176 UpdateOnlyClosure::UpdateOnlyClosure(ParMarkBitMap* mbm,
3177                                      ParCompactionManager* cm,
3178                                      PSParallelCompact::SpaceId space_id) :
3179   ParMarkBitMapClosure(mbm, cm),
3180   _space_id(space_id),
3181   _start_array(PSParallelCompact::start_array(space_id))
3182 {
3183 }
3184 
3185 // Updates the references in the object to their new values.
3186 ParMarkBitMapClosure::IterationStatus
3187 UpdateOnlyClosure::do_addr(HeapWord* addr, size_t words) {
3188   do_addr(addr);
3189   return ParMarkBitMap::incomplete;
3190 }
3191 
3192 FillClosure::FillClosure(ParCompactionManager* cm, PSParallelCompact::SpaceId space_id) :
3193   ParMarkBitMapClosure(PSParallelCompact::mark_bitmap(), cm),
3194   _start_array(PSParallelCompact::start_array(space_id))
3195 {
3196   assert(space_id == PSParallelCompact::old_space_id,
3197          "cannot use FillClosure in the young gen");
3198 }
3199 
3200 ParMarkBitMapClosure::IterationStatus
3201 FillClosure::do_addr(HeapWord* addr, size_t size) {
3202   CollectedHeap::fill_with_objects(addr, size);
3203   HeapWord* const end = addr + size;
3204   do {
3205     _start_array->allocate_block(addr);
3206     addr += oop(addr)->size();
3207   } while (addr < end);
3208   return ParMarkBitMap::incomplete;
3209 }