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