1 /*
   2  * Copyright (c) 2005, 2021, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "classfile/classLoaderDataGraph.hpp"
  27 #include "classfile/javaClasses.inline.hpp"
  28 #include "classfile/stringTable.hpp"
  29 #include "classfile/symbolTable.hpp"
  30 #include "classfile/systemDictionary.hpp"
  31 #include "code/codeCache.hpp"
  32 #include "compiler/oopMap.hpp"
  33 #include "gc/parallel/parallelArguments.hpp"
  34 #include "gc/parallel/parallelScavengeHeap.inline.hpp"
  35 #include "gc/parallel/parMarkBitMap.inline.hpp"
  36 #include "gc/parallel/psAdaptiveSizePolicy.hpp"
  37 #include "gc/parallel/psCompactionManager.inline.hpp"
  38 #include "gc/parallel/psOldGen.hpp"
  39 #include "gc/parallel/psParallelCompact.inline.hpp"
  40 #include "gc/parallel/psPromotionManager.inline.hpp"
  41 #include "gc/parallel/psRootType.hpp"
  42 #include "gc/parallel/psScavenge.hpp"
  43 #include "gc/parallel/psStringDedup.hpp"
  44 #include "gc/parallel/psYoungGen.hpp"
  45 #include "gc/shared/gcCause.hpp"
  46 #include "gc/shared/gcHeapSummary.hpp"
  47 #include "gc/shared/gcId.hpp"
  48 #include "gc/shared/gcLocker.hpp"
  49 #include "gc/shared/gcTimer.hpp"
  50 #include "gc/shared/gcTrace.hpp"
  51 #include "gc/shared/gcTraceTime.inline.hpp"
  52 #include "gc/shared/isGCActiveMark.hpp"
  53 #include "gc/shared/oopStorage.inline.hpp"
  54 #include "gc/shared/oopStorageSet.inline.hpp"
  55 #include "gc/shared/oopStorageSetParState.inline.hpp"
  56 #include "gc/shared/referencePolicy.hpp"
  57 #include "gc/shared/referenceProcessor.hpp"
  58 #include "gc/shared/referenceProcessorPhaseTimes.hpp"
  59 #include "gc/shared/spaceDecorator.inline.hpp"
  60 #include "gc/shared/taskTerminator.hpp"
  61 #include "gc/shared/weakProcessor.inline.hpp"
  62 #include "gc/shared/workerPolicy.hpp"
  63 #include "gc/shared/workgroup.hpp"
  64 #include "logging/log.hpp"
  65 #include "memory/iterator.inline.hpp"
  66 #include "memory/metaspaceUtils.hpp"
  67 #include "memory/resourceArea.hpp"
  68 #include "memory/universe.hpp"
  69 #include "oops/access.inline.hpp"
  70 #include "oops/flatArrayKlass.inline.hpp"
  71 #include "oops/instanceClassLoaderKlass.inline.hpp"
  72 #include "oops/instanceKlass.inline.hpp"
  73 #include "oops/instanceMirrorKlass.inline.hpp"
  74 #include "oops/methodData.hpp"
  75 #include "oops/objArrayKlass.inline.hpp"
  76 #include "oops/oop.inline.hpp"
  77 #include "runtime/atomic.hpp"
  78 #include "runtime/handles.inline.hpp"
  79 #include "runtime/java.hpp"
  80 #include "runtime/safepoint.hpp"
  81 #include "runtime/vmThread.hpp"
  82 #include "services/memTracker.hpp"
  83 #include "services/memoryService.hpp"
  84 #include "utilities/align.hpp"
  85 #include "utilities/debug.hpp"
  86 #include "utilities/events.hpp"
  87 #include "utilities/formatBuffer.hpp"
  88 #include "utilities/macros.hpp"
  89 #include "utilities/stack.inline.hpp"
  90 #if INCLUDE_JVMCI
  91 #include "jvmci/jvmci.hpp"
  92 #endif
  93 
  94 #include <math.h>
  95 
  96 // All sizes are in HeapWords.
  97 const size_t ParallelCompactData::Log2RegionSize  = 16; // 64K words
  98 const size_t ParallelCompactData::RegionSize      = (size_t)1 << Log2RegionSize;
  99 const size_t ParallelCompactData::RegionSizeBytes =
 100   RegionSize << LogHeapWordSize;
 101 const size_t ParallelCompactData::RegionSizeOffsetMask = RegionSize - 1;
 102 const size_t ParallelCompactData::RegionAddrOffsetMask = RegionSizeBytes - 1;
 103 const size_t ParallelCompactData::RegionAddrMask       = ~RegionAddrOffsetMask;
 104 
 105 const size_t ParallelCompactData::Log2BlockSize   = 7; // 128 words
 106 const size_t ParallelCompactData::BlockSize       = (size_t)1 << Log2BlockSize;
 107 const size_t ParallelCompactData::BlockSizeBytes  =
 108   BlockSize << LogHeapWordSize;
 109 const size_t ParallelCompactData::BlockSizeOffsetMask = BlockSize - 1;
 110 const size_t ParallelCompactData::BlockAddrOffsetMask = BlockSizeBytes - 1;
 111 const size_t ParallelCompactData::BlockAddrMask       = ~BlockAddrOffsetMask;
 112 
 113 const size_t ParallelCompactData::BlocksPerRegion = RegionSize / BlockSize;
 114 const size_t ParallelCompactData::Log2BlocksPerRegion =
 115   Log2RegionSize - Log2BlockSize;
 116 
 117 const ParallelCompactData::RegionData::region_sz_t
 118 ParallelCompactData::RegionData::dc_shift = 27;
 119 
 120 const ParallelCompactData::RegionData::region_sz_t
 121 ParallelCompactData::RegionData::dc_mask = ~0U << dc_shift;
 122 
 123 const ParallelCompactData::RegionData::region_sz_t
 124 ParallelCompactData::RegionData::dc_one = 0x1U << dc_shift;
 125 
 126 const ParallelCompactData::RegionData::region_sz_t
 127 ParallelCompactData::RegionData::los_mask = ~dc_mask;
 128 
 129 const ParallelCompactData::RegionData::region_sz_t
 130 ParallelCompactData::RegionData::dc_claimed = 0x8U << dc_shift;
 131 
 132 const ParallelCompactData::RegionData::region_sz_t
 133 ParallelCompactData::RegionData::dc_completed = 0xcU << dc_shift;
 134 
 135 SpaceInfo PSParallelCompact::_space_info[PSParallelCompact::last_space_id];
 136 
 137 SpanSubjectToDiscoveryClosure PSParallelCompact::_span_based_discoverer;
 138 ReferenceProcessor* PSParallelCompact::_ref_processor = NULL;
 139 
 140 double PSParallelCompact::_dwl_mean;
 141 double PSParallelCompact::_dwl_std_dev;
 142 double PSParallelCompact::_dwl_first_term;
 143 double PSParallelCompact::_dwl_adjustment;
 144 #ifdef  ASSERT
 145 bool   PSParallelCompact::_dwl_initialized = false;
 146 #endif  // #ifdef ASSERT
 147 
 148 void SplitInfo::record(size_t src_region_idx, size_t partial_obj_size,
 149                        HeapWord* destination)
 150 {
 151   assert(src_region_idx != 0, "invalid src_region_idx");
 152   assert(partial_obj_size != 0, "invalid partial_obj_size argument");
 153   assert(destination != NULL, "invalid destination argument");
 154 
 155   _src_region_idx = src_region_idx;
 156   _partial_obj_size = partial_obj_size;
 157   _destination = destination;
 158 
 159   // These fields may not be updated below, so make sure they're clear.
 160   assert(_dest_region_addr == NULL, "should have been cleared");
 161   assert(_first_src_addr == NULL, "should have been cleared");
 162 
 163   // Determine the number of destination regions for the partial object.
 164   HeapWord* const last_word = destination + partial_obj_size - 1;
 165   const ParallelCompactData& sd = PSParallelCompact::summary_data();
 166   HeapWord* const beg_region_addr = sd.region_align_down(destination);
 167   HeapWord* const end_region_addr = sd.region_align_down(last_word);
 168 
 169   if (beg_region_addr == end_region_addr) {
 170     // One destination region.
 171     _destination_count = 1;
 172     if (end_region_addr == destination) {
 173       // The destination falls on a region boundary, thus the first word of the
 174       // partial object will be the first word copied to the destination region.
 175       _dest_region_addr = end_region_addr;
 176       _first_src_addr = sd.region_to_addr(src_region_idx);
 177     }
 178   } else {
 179     // Two destination regions.  When copied, the partial object will cross a
 180     // destination region boundary, so a word somewhere within the partial
 181     // object will be the first word copied to the second destination region.
 182     _destination_count = 2;
 183     _dest_region_addr = end_region_addr;
 184     const size_t ofs = pointer_delta(end_region_addr, destination);
 185     assert(ofs < _partial_obj_size, "sanity");
 186     _first_src_addr = sd.region_to_addr(src_region_idx) + ofs;
 187   }
 188 }
 189 
 190 void SplitInfo::clear()
 191 {
 192   _src_region_idx = 0;
 193   _partial_obj_size = 0;
 194   _destination = NULL;
 195   _destination_count = 0;
 196   _dest_region_addr = NULL;
 197   _first_src_addr = NULL;
 198   assert(!is_valid(), "sanity");
 199 }
 200 
 201 #ifdef  ASSERT
 202 void SplitInfo::verify_clear()
 203 {
 204   assert(_src_region_idx == 0, "not clear");
 205   assert(_partial_obj_size == 0, "not clear");
 206   assert(_destination == NULL, "not clear");
 207   assert(_destination_count == 0, "not clear");
 208   assert(_dest_region_addr == NULL, "not clear");
 209   assert(_first_src_addr == NULL, "not clear");
 210 }
 211 #endif  // #ifdef ASSERT
 212 
 213 
 214 void PSParallelCompact::print_on_error(outputStream* st) {
 215   _mark_bitmap.print_on_error(st);
 216 }
 217 
 218 #ifndef PRODUCT
 219 const char* PSParallelCompact::space_names[] = {
 220   "old ", "eden", "from", "to  "
 221 };
 222 
 223 void PSParallelCompact::print_region_ranges() {
 224   if (!log_develop_is_enabled(Trace, gc, compaction)) {
 225     return;
 226   }
 227   Log(gc, compaction) log;
 228   ResourceMark rm;
 229   LogStream ls(log.trace());
 230   Universe::print_on(&ls);
 231   log.trace("space  bottom     top        end        new_top");
 232   log.trace("------ ---------- ---------- ---------- ----------");
 233 
 234   for (unsigned int id = 0; id < last_space_id; ++id) {
 235     const MutableSpace* space = _space_info[id].space();
 236     log.trace("%u %s "
 237               SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " "
 238               SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " ",
 239               id, space_names[id],
 240               summary_data().addr_to_region_idx(space->bottom()),
 241               summary_data().addr_to_region_idx(space->top()),
 242               summary_data().addr_to_region_idx(space->end()),
 243               summary_data().addr_to_region_idx(_space_info[id].new_top()));
 244   }
 245 }
 246 
 247 void
 248 print_generic_summary_region(size_t i, const ParallelCompactData::RegionData* c)
 249 {
 250 #define REGION_IDX_FORMAT        SIZE_FORMAT_W(7)
 251 #define REGION_DATA_FORMAT       SIZE_FORMAT_W(5)
 252 
 253   ParallelCompactData& sd = PSParallelCompact::summary_data();
 254   size_t dci = c->destination() ? sd.addr_to_region_idx(c->destination()) : 0;
 255   log_develop_trace(gc, compaction)(
 256       REGION_IDX_FORMAT " " PTR_FORMAT " "
 257       REGION_IDX_FORMAT " " PTR_FORMAT " "
 258       REGION_DATA_FORMAT " " REGION_DATA_FORMAT " "
 259       REGION_DATA_FORMAT " " REGION_IDX_FORMAT " %d",
 260       i, p2i(c->data_location()), dci, p2i(c->destination()),
 261       c->partial_obj_size(), c->live_obj_size(),
 262       c->data_size(), c->source_region(), c->destination_count());
 263 
 264 #undef  REGION_IDX_FORMAT
 265 #undef  REGION_DATA_FORMAT
 266 }
 267 
 268 void
 269 print_generic_summary_data(ParallelCompactData& summary_data,
 270                            HeapWord* const beg_addr,
 271                            HeapWord* const end_addr)
 272 {
 273   size_t total_words = 0;
 274   size_t i = summary_data.addr_to_region_idx(beg_addr);
 275   const size_t last = summary_data.addr_to_region_idx(end_addr);
 276   HeapWord* pdest = 0;
 277 
 278   while (i < last) {
 279     ParallelCompactData::RegionData* c = summary_data.region(i);
 280     if (c->data_size() != 0 || c->destination() != pdest) {
 281       print_generic_summary_region(i, c);
 282       total_words += c->data_size();
 283       pdest = c->destination();
 284     }
 285     ++i;
 286   }
 287 
 288   log_develop_trace(gc, compaction)("summary_data_bytes=" SIZE_FORMAT, total_words * HeapWordSize);
 289 }
 290 
 291 void
 292 PSParallelCompact::print_generic_summary_data(ParallelCompactData& summary_data,
 293                                               HeapWord* const beg_addr,
 294                                               HeapWord* const end_addr) {
 295   ::print_generic_summary_data(summary_data,beg_addr, end_addr);
 296 }
 297 
 298 void
 299 print_generic_summary_data(ParallelCompactData& summary_data,
 300                            SpaceInfo* space_info)
 301 {
 302   if (!log_develop_is_enabled(Trace, gc, compaction)) {
 303     return;
 304   }
 305 
 306   for (unsigned int id = 0; id < PSParallelCompact::last_space_id; ++id) {
 307     const MutableSpace* space = space_info[id].space();
 308     print_generic_summary_data(summary_data, space->bottom(),
 309                                MAX2(space->top(), space_info[id].new_top()));
 310   }
 311 }
 312 
 313 void
 314 print_initial_summary_data(ParallelCompactData& summary_data,
 315                            const MutableSpace* space) {
 316   if (space->top() == space->bottom()) {
 317     return;
 318   }
 319 
 320   const size_t region_size = ParallelCompactData::RegionSize;
 321   typedef ParallelCompactData::RegionData RegionData;
 322   HeapWord* const top_aligned_up = summary_data.region_align_up(space->top());
 323   const size_t end_region = summary_data.addr_to_region_idx(top_aligned_up);
 324   const RegionData* c = summary_data.region(end_region - 1);
 325   HeapWord* end_addr = c->destination() + c->data_size();
 326   const size_t live_in_space = pointer_delta(end_addr, space->bottom());
 327 
 328   // Print (and count) the full regions at the beginning of the space.
 329   size_t full_region_count = 0;
 330   size_t i = summary_data.addr_to_region_idx(space->bottom());
 331   while (i < end_region && summary_data.region(i)->data_size() == region_size) {
 332     ParallelCompactData::RegionData* c = summary_data.region(i);
 333     log_develop_trace(gc, compaction)(
 334         SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d",
 335         i, p2i(c->destination()),
 336         c->partial_obj_size(), c->live_obj_size(),
 337         c->data_size(), c->source_region(), c->destination_count());
 338     ++full_region_count;
 339     ++i;
 340   }
 341 
 342   size_t live_to_right = live_in_space - full_region_count * region_size;
 343 
 344   double max_reclaimed_ratio = 0.0;
 345   size_t max_reclaimed_ratio_region = 0;
 346   size_t max_dead_to_right = 0;
 347   size_t max_live_to_right = 0;
 348 
 349   // Print the 'reclaimed ratio' for regions while there is something live in
 350   // the region or to the right of it.  The remaining regions are empty (and
 351   // uninteresting), and computing the ratio will result in division by 0.
 352   while (i < end_region && live_to_right > 0) {
 353     c = summary_data.region(i);
 354     HeapWord* const region_addr = summary_data.region_to_addr(i);
 355     const size_t used_to_right = pointer_delta(space->top(), region_addr);
 356     const size_t dead_to_right = used_to_right - live_to_right;
 357     const double reclaimed_ratio = double(dead_to_right) / live_to_right;
 358 
 359     if (reclaimed_ratio > max_reclaimed_ratio) {
 360             max_reclaimed_ratio = reclaimed_ratio;
 361             max_reclaimed_ratio_region = i;
 362             max_dead_to_right = dead_to_right;
 363             max_live_to_right = live_to_right;
 364     }
 365 
 366     ParallelCompactData::RegionData* c = summary_data.region(i);
 367     log_develop_trace(gc, compaction)(
 368         SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d"
 369         "%12.10f " SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10),
 370         i, p2i(c->destination()),
 371         c->partial_obj_size(), c->live_obj_size(),
 372         c->data_size(), c->source_region(), c->destination_count(),
 373         reclaimed_ratio, dead_to_right, live_to_right);
 374 
 375 
 376     live_to_right -= c->data_size();
 377     ++i;
 378   }
 379 
 380   // Any remaining regions are empty.  Print one more if there is one.
 381   if (i < end_region) {
 382     ParallelCompactData::RegionData* c = summary_data.region(i);
 383     log_develop_trace(gc, compaction)(
 384         SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d",
 385          i, p2i(c->destination()),
 386          c->partial_obj_size(), c->live_obj_size(),
 387          c->data_size(), c->source_region(), c->destination_count());
 388   }
 389 
 390   log_develop_trace(gc, compaction)("max:  " SIZE_FORMAT_W(4) " d2r=" SIZE_FORMAT_W(10) " l2r=" SIZE_FORMAT_W(10) " max_ratio=%14.12f",
 391                                     max_reclaimed_ratio_region, max_dead_to_right, max_live_to_right, max_reclaimed_ratio);
 392 }
 393 
 394 void
 395 print_initial_summary_data(ParallelCompactData& summary_data,
 396                            SpaceInfo* space_info) {
 397   if (!log_develop_is_enabled(Trace, gc, compaction)) {
 398     return;
 399   }
 400 
 401   unsigned int id = PSParallelCompact::old_space_id;
 402   const MutableSpace* space;
 403   do {
 404     space = space_info[id].space();
 405     print_initial_summary_data(summary_data, space);
 406   } while (++id < PSParallelCompact::eden_space_id);
 407 
 408   do {
 409     space = space_info[id].space();
 410     print_generic_summary_data(summary_data, space->bottom(), space->top());
 411   } while (++id < PSParallelCompact::last_space_id);
 412 }
 413 #endif  // #ifndef PRODUCT
 414 
 415 ParallelCompactData::ParallelCompactData() :
 416   _region_start(NULL),
 417   DEBUG_ONLY(_region_end(NULL) COMMA)
 418   _region_vspace(NULL),
 419   _reserved_byte_size(0),
 420   _region_data(NULL),
 421   _region_count(0),
 422   _block_vspace(NULL),
 423   _block_data(NULL),
 424   _block_count(0) {}
 425 
 426 bool ParallelCompactData::initialize(MemRegion covered_region)
 427 {
 428   _region_start = covered_region.start();
 429   const size_t region_size = covered_region.word_size();
 430   DEBUG_ONLY(_region_end = _region_start + region_size;)
 431 
 432   assert(region_align_down(_region_start) == _region_start,
 433          "region start not aligned");
 434   assert((region_size & RegionSizeOffsetMask) == 0,
 435          "region size not a multiple of RegionSize");
 436 
 437   bool result = initialize_region_data(region_size) && initialize_block_data();
 438   return result;
 439 }
 440 
 441 PSVirtualSpace*
 442 ParallelCompactData::create_vspace(size_t count, size_t element_size)
 443 {
 444   const size_t raw_bytes = count * element_size;
 445   const size_t page_sz = os::page_size_for_region_aligned(raw_bytes, 10);
 446   const size_t granularity = os::vm_allocation_granularity();
 447   _reserved_byte_size = align_up(raw_bytes, MAX2(page_sz, granularity));
 448 
 449   const size_t rs_align = page_sz == (size_t) os::vm_page_size() ? 0 :
 450     MAX2(page_sz, granularity);
 451   ReservedSpace rs(_reserved_byte_size, rs_align, page_sz);
 452   os::trace_page_sizes("Parallel Compact Data", raw_bytes, raw_bytes, page_sz, rs.base(),
 453                        rs.size());
 454 
 455   MemTracker::record_virtual_memory_type((address)rs.base(), mtGC);
 456 
 457   PSVirtualSpace* vspace = new PSVirtualSpace(rs, page_sz);
 458   if (vspace != 0) {
 459     if (vspace->expand_by(_reserved_byte_size)) {
 460       return vspace;
 461     }
 462     delete vspace;
 463     // Release memory reserved in the space.
 464     rs.release();
 465   }
 466 
 467   return 0;
 468 }
 469 
 470 bool ParallelCompactData::initialize_region_data(size_t region_size)
 471 {
 472   const size_t count = (region_size + RegionSizeOffsetMask) >> Log2RegionSize;
 473   _region_vspace = create_vspace(count, sizeof(RegionData));
 474   if (_region_vspace != 0) {
 475     _region_data = (RegionData*)_region_vspace->reserved_low_addr();
 476     _region_count = count;
 477     return true;
 478   }
 479   return false;
 480 }
 481 
 482 bool ParallelCompactData::initialize_block_data()
 483 {
 484   assert(_region_count != 0, "region data must be initialized first");
 485   const size_t count = _region_count << Log2BlocksPerRegion;
 486   _block_vspace = create_vspace(count, sizeof(BlockData));
 487   if (_block_vspace != 0) {
 488     _block_data = (BlockData*)_block_vspace->reserved_low_addr();
 489     _block_count = count;
 490     return true;
 491   }
 492   return false;
 493 }
 494 
 495 void ParallelCompactData::clear()
 496 {
 497   memset(_region_data, 0, _region_vspace->committed_size());
 498   memset(_block_data, 0, _block_vspace->committed_size());
 499 }
 500 
 501 void ParallelCompactData::clear_range(size_t beg_region, size_t end_region) {
 502   assert(beg_region <= _region_count, "beg_region out of range");
 503   assert(end_region <= _region_count, "end_region out of range");
 504   assert(RegionSize % BlockSize == 0, "RegionSize not a multiple of BlockSize");
 505 
 506   const size_t region_cnt = end_region - beg_region;
 507   memset(_region_data + beg_region, 0, region_cnt * sizeof(RegionData));
 508 
 509   const size_t beg_block = beg_region * BlocksPerRegion;
 510   const size_t block_cnt = region_cnt * BlocksPerRegion;
 511   memset(_block_data + beg_block, 0, block_cnt * sizeof(BlockData));
 512 }
 513 
 514 HeapWord* ParallelCompactData::partial_obj_end(size_t region_idx) const
 515 {
 516   const RegionData* cur_cp = region(region_idx);
 517   const RegionData* const end_cp = region(region_count() - 1);
 518 
 519   HeapWord* result = region_to_addr(region_idx);
 520   if (cur_cp < end_cp) {
 521     do {
 522       result += cur_cp->partial_obj_size();
 523     } while (cur_cp->partial_obj_size() == RegionSize && ++cur_cp < end_cp);
 524   }
 525   return result;
 526 }
 527 
 528 void ParallelCompactData::add_obj(HeapWord* addr, size_t len)
 529 {
 530   const size_t obj_ofs = pointer_delta(addr, _region_start);
 531   const size_t beg_region = obj_ofs >> Log2RegionSize;
 532   // end_region is inclusive
 533   const size_t end_region = (obj_ofs + len - 1) >> Log2RegionSize;
 534 
 535   if (beg_region == end_region) {
 536     // All in one region.
 537     _region_data[beg_region].add_live_obj(len);
 538     return;
 539   }
 540 
 541   // First region.
 542   const size_t beg_ofs = region_offset(addr);
 543   _region_data[beg_region].add_live_obj(RegionSize - beg_ofs);
 544 
 545   // Middle regions--completely spanned by this object.
 546   for (size_t region = beg_region + 1; region < end_region; ++region) {
 547     _region_data[region].set_partial_obj_size(RegionSize);
 548     _region_data[region].set_partial_obj_addr(addr);
 549   }
 550 
 551   // Last region.
 552   const size_t end_ofs = region_offset(addr + len - 1);
 553   _region_data[end_region].set_partial_obj_size(end_ofs + 1);
 554   _region_data[end_region].set_partial_obj_addr(addr);
 555 }
 556 
 557 void
 558 ParallelCompactData::summarize_dense_prefix(HeapWord* beg, HeapWord* end)
 559 {
 560   assert(is_region_aligned(beg), "not RegionSize aligned");
 561   assert(is_region_aligned(end), "not RegionSize aligned");
 562 
 563   size_t cur_region = addr_to_region_idx(beg);
 564   const size_t end_region = addr_to_region_idx(end);
 565   HeapWord* addr = beg;
 566   while (cur_region < end_region) {
 567     _region_data[cur_region].set_destination(addr);
 568     _region_data[cur_region].set_destination_count(0);
 569     _region_data[cur_region].set_source_region(cur_region);
 570     _region_data[cur_region].set_data_location(addr);
 571 
 572     // Update live_obj_size so the region appears completely full.
 573     size_t live_size = RegionSize - _region_data[cur_region].partial_obj_size();
 574     _region_data[cur_region].set_live_obj_size(live_size);
 575 
 576     ++cur_region;
 577     addr += RegionSize;
 578   }
 579 }
 580 
 581 // Find the point at which a space can be split and, if necessary, record the
 582 // split point.
 583 //
 584 // If the current src region (which overflowed the destination space) doesn't
 585 // have a partial object, the split point is at the beginning of the current src
 586 // region (an "easy" split, no extra bookkeeping required).
 587 //
 588 // If the current src region has a partial object, the split point is in the
 589 // region where that partial object starts (call it the split_region).  If
 590 // split_region has a partial object, then the split point is just after that
 591 // partial object (a "hard" split where we have to record the split data and
 592 // zero the partial_obj_size field).  With a "hard" split, we know that the
 593 // partial_obj ends within split_region because the partial object that caused
 594 // the overflow starts in split_region.  If split_region doesn't have a partial
 595 // obj, then the split is at the beginning of split_region (another "easy"
 596 // split).
 597 HeapWord*
 598 ParallelCompactData::summarize_split_space(size_t src_region,
 599                                            SplitInfo& split_info,
 600                                            HeapWord* destination,
 601                                            HeapWord* target_end,
 602                                            HeapWord** target_next)
 603 {
 604   assert(destination <= target_end, "sanity");
 605   assert(destination + _region_data[src_region].data_size() > target_end,
 606     "region should not fit into target space");
 607   assert(is_region_aligned(target_end), "sanity");
 608 
 609   size_t split_region = src_region;
 610   HeapWord* split_destination = destination;
 611   size_t partial_obj_size = _region_data[src_region].partial_obj_size();
 612 
 613   if (destination + partial_obj_size > target_end) {
 614     // The split point is just after the partial object (if any) in the
 615     // src_region that contains the start of the object that overflowed the
 616     // destination space.
 617     //
 618     // Find the start of the "overflow" object and set split_region to the
 619     // region containing it.
 620     HeapWord* const overflow_obj = _region_data[src_region].partial_obj_addr();
 621     split_region = addr_to_region_idx(overflow_obj);
 622 
 623     // Clear the source_region field of all destination regions whose first word
 624     // came from data after the split point (a non-null source_region field
 625     // implies a region must be filled).
 626     //
 627     // An alternative to the simple loop below:  clear during post_compact(),
 628     // which uses memcpy instead of individual stores, and is easy to
 629     // parallelize.  (The downside is that it clears the entire RegionData
 630     // object as opposed to just one field.)
 631     //
 632     // post_compact() would have to clear the summary data up to the highest
 633     // address that was written during the summary phase, which would be
 634     //
 635     //         max(top, max(new_top, clear_top))
 636     //
 637     // where clear_top is a new field in SpaceInfo.  Would have to set clear_top
 638     // to target_end.
 639     const RegionData* const sr = region(split_region);
 640     const size_t beg_idx =
 641       addr_to_region_idx(region_align_up(sr->destination() +
 642                                          sr->partial_obj_size()));
 643     const size_t end_idx = addr_to_region_idx(target_end);
 644 
 645     log_develop_trace(gc, compaction)("split:  clearing source_region field in [" SIZE_FORMAT ", " SIZE_FORMAT ")", beg_idx, end_idx);
 646     for (size_t idx = beg_idx; idx < end_idx; ++idx) {
 647       _region_data[idx].set_source_region(0);
 648     }
 649 
 650     // Set split_destination and partial_obj_size to reflect the split region.
 651     split_destination = sr->destination();
 652     partial_obj_size = sr->partial_obj_size();
 653   }
 654 
 655   // The split is recorded only if a partial object extends onto the region.
 656   if (partial_obj_size != 0) {
 657     _region_data[split_region].set_partial_obj_size(0);
 658     split_info.record(split_region, partial_obj_size, split_destination);
 659   }
 660 
 661   // Setup the continuation addresses.
 662   *target_next = split_destination + partial_obj_size;
 663   HeapWord* const source_next = region_to_addr(split_region) + partial_obj_size;
 664 
 665   if (log_develop_is_enabled(Trace, gc, compaction)) {
 666     const char * split_type = partial_obj_size == 0 ? "easy" : "hard";
 667     log_develop_trace(gc, compaction)("%s split:  src=" PTR_FORMAT " src_c=" SIZE_FORMAT " pos=" SIZE_FORMAT,
 668                                       split_type, p2i(source_next), split_region, partial_obj_size);
 669     log_develop_trace(gc, compaction)("%s split:  dst=" PTR_FORMAT " dst_c=" SIZE_FORMAT " tn=" PTR_FORMAT,
 670                                       split_type, p2i(split_destination),
 671                                       addr_to_region_idx(split_destination),
 672                                       p2i(*target_next));
 673 
 674     if (partial_obj_size != 0) {
 675       HeapWord* const po_beg = split_info.destination();
 676       HeapWord* const po_end = po_beg + split_info.partial_obj_size();
 677       log_develop_trace(gc, compaction)("%s split:  po_beg=" PTR_FORMAT " " SIZE_FORMAT " po_end=" PTR_FORMAT " " SIZE_FORMAT,
 678                                         split_type,
 679                                         p2i(po_beg), addr_to_region_idx(po_beg),
 680                                         p2i(po_end), addr_to_region_idx(po_end));
 681     }
 682   }
 683 
 684   return source_next;
 685 }
 686 
 687 bool ParallelCompactData::summarize(SplitInfo& split_info,
 688                                     HeapWord* source_beg, HeapWord* source_end,
 689                                     HeapWord** source_next,
 690                                     HeapWord* target_beg, HeapWord* target_end,
 691                                     HeapWord** target_next)
 692 {
 693   HeapWord* const source_next_val = source_next == NULL ? NULL : *source_next;
 694   log_develop_trace(gc, compaction)(
 695       "sb=" PTR_FORMAT " se=" PTR_FORMAT " sn=" PTR_FORMAT
 696       "tb=" PTR_FORMAT " te=" PTR_FORMAT " tn=" PTR_FORMAT,
 697       p2i(source_beg), p2i(source_end), p2i(source_next_val),
 698       p2i(target_beg), p2i(target_end), p2i(*target_next));
 699 
 700   size_t cur_region = addr_to_region_idx(source_beg);
 701   const size_t end_region = addr_to_region_idx(region_align_up(source_end));
 702 
 703   HeapWord *dest_addr = target_beg;
 704   while (cur_region < end_region) {
 705     // The destination must be set even if the region has no data.
 706     _region_data[cur_region].set_destination(dest_addr);
 707 
 708     size_t words = _region_data[cur_region].data_size();
 709     if (words > 0) {
 710       // If cur_region does not fit entirely into the target space, find a point
 711       // at which the source space can be 'split' so that part is copied to the
 712       // target space and the rest is copied elsewhere.
 713       if (dest_addr + words > target_end) {
 714         assert(source_next != NULL, "source_next is NULL when splitting");
 715         *source_next = summarize_split_space(cur_region, split_info, dest_addr,
 716                                              target_end, target_next);
 717         return false;
 718       }
 719 
 720       // Compute the destination_count for cur_region, and if necessary, update
 721       // source_region for a destination region.  The source_region field is
 722       // updated if cur_region is the first (left-most) region to be copied to a
 723       // destination region.
 724       //
 725       // The destination_count calculation is a bit subtle.  A region that has
 726       // data that compacts into itself does not count itself as a destination.
 727       // This maintains the invariant that a zero count means the region is
 728       // available and can be claimed and then filled.
 729       uint destination_count = 0;
 730       if (split_info.is_split(cur_region)) {
 731         // The current region has been split:  the partial object will be copied
 732         // to one destination space and the remaining data will be copied to
 733         // another destination space.  Adjust the initial destination_count and,
 734         // if necessary, set the source_region field if the partial object will
 735         // cross a destination region boundary.
 736         destination_count = split_info.destination_count();
 737         if (destination_count == 2) {
 738           size_t dest_idx = addr_to_region_idx(split_info.dest_region_addr());
 739           _region_data[dest_idx].set_source_region(cur_region);
 740         }
 741       }
 742 
 743       HeapWord* const last_addr = dest_addr + words - 1;
 744       const size_t dest_region_1 = addr_to_region_idx(dest_addr);
 745       const size_t dest_region_2 = addr_to_region_idx(last_addr);
 746 
 747       // Initially assume that the destination regions will be the same and
 748       // adjust the value below if necessary.  Under this assumption, if
 749       // cur_region == dest_region_2, then cur_region will be compacted
 750       // completely into itself.
 751       destination_count += cur_region == dest_region_2 ? 0 : 1;
 752       if (dest_region_1 != dest_region_2) {
 753         // Destination regions differ; adjust destination_count.
 754         destination_count += 1;
 755         // Data from cur_region will be copied to the start of dest_region_2.
 756         _region_data[dest_region_2].set_source_region(cur_region);
 757       } else if (is_region_aligned(dest_addr)) {
 758         // Data from cur_region will be copied to the start of the destination
 759         // region.
 760         _region_data[dest_region_1].set_source_region(cur_region);
 761       }
 762 
 763       _region_data[cur_region].set_destination_count(destination_count);
 764       _region_data[cur_region].set_data_location(region_to_addr(cur_region));
 765       dest_addr += words;
 766     }
 767 
 768     ++cur_region;
 769   }
 770 
 771   *target_next = dest_addr;
 772   return true;
 773 }
 774 
 775 HeapWord* ParallelCompactData::calc_new_pointer(HeapWord* addr, ParCompactionManager* cm) const {
 776   assert(addr != NULL, "Should detect NULL oop earlier");
 777   assert(ParallelScavengeHeap::heap()->is_in(addr), "not in heap");
 778   assert(PSParallelCompact::mark_bitmap()->is_marked(addr), "not marked");
 779 
 780   // Region covering the object.
 781   RegionData* const region_ptr = addr_to_region_ptr(addr);
 782   HeapWord* result = region_ptr->destination();
 783 
 784   // If the entire Region is live, the new location is region->destination + the
 785   // offset of the object within in the Region.
 786 
 787   // Run some performance tests to determine if this special case pays off.  It
 788   // is worth it for pointers into the dense prefix.  If the optimization to
 789   // avoid pointer updates in regions that only point to the dense prefix is
 790   // ever implemented, this should be revisited.
 791   if (region_ptr->data_size() == RegionSize) {
 792     result += region_offset(addr);
 793     return result;
 794   }
 795 
 796   // Otherwise, the new location is region->destination + block offset + the
 797   // number of live words in the Block that are (a) to the left of addr and (b)
 798   // due to objects that start in the Block.
 799 
 800   // Fill in the block table if necessary.  This is unsynchronized, so multiple
 801   // threads may fill the block table for a region (harmless, since it is
 802   // idempotent).
 803   if (!region_ptr->blocks_filled()) {
 804     PSParallelCompact::fill_blocks(addr_to_region_idx(addr));
 805     region_ptr->set_blocks_filled();
 806   }
 807 
 808   HeapWord* const search_start = block_align_down(addr);
 809   const size_t block_offset = addr_to_block_ptr(addr)->offset();
 810 
 811   const ParMarkBitMap* bitmap = PSParallelCompact::mark_bitmap();
 812   const size_t live = bitmap->live_words_in_range(cm, search_start, cast_to_oop(addr));
 813   result += block_offset + live;
 814   DEBUG_ONLY(PSParallelCompact::check_new_location(addr, result));
 815   return result;
 816 }
 817 
 818 #ifdef ASSERT
 819 void ParallelCompactData::verify_clear(const PSVirtualSpace* vspace)
 820 {
 821   const size_t* const beg = (const size_t*)vspace->committed_low_addr();
 822   const size_t* const end = (const size_t*)vspace->committed_high_addr();
 823   for (const size_t* p = beg; p < end; ++p) {
 824     assert(*p == 0, "not zero");
 825   }
 826 }
 827 
 828 void ParallelCompactData::verify_clear()
 829 {
 830   verify_clear(_region_vspace);
 831   verify_clear(_block_vspace);
 832 }
 833 #endif  // #ifdef ASSERT
 834 
 835 STWGCTimer          PSParallelCompact::_gc_timer;
 836 ParallelOldTracer   PSParallelCompact::_gc_tracer;
 837 elapsedTimer        PSParallelCompact::_accumulated_time;
 838 unsigned int        PSParallelCompact::_total_invocations = 0;
 839 unsigned int        PSParallelCompact::_maximum_compaction_gc_num = 0;
 840 CollectorCounters*  PSParallelCompact::_counters = NULL;
 841 ParMarkBitMap       PSParallelCompact::_mark_bitmap;
 842 ParallelCompactData PSParallelCompact::_summary_data;
 843 
 844 PSParallelCompact::IsAliveClosure PSParallelCompact::_is_alive_closure;
 845 
 846 bool PSParallelCompact::IsAliveClosure::do_object_b(oop p) { return mark_bitmap()->is_marked(p); }
 847 
 848 class PCReferenceProcessor: public ReferenceProcessor {
 849 public:
 850   PCReferenceProcessor(
 851     BoolObjectClosure* is_subject_to_discovery,
 852     BoolObjectClosure* is_alive_non_header) :
 853       ReferenceProcessor(is_subject_to_discovery,
 854       ParallelGCThreads,   // mt processing degree
 855       true,                // mt discovery
 856       ParallelGCThreads,   // mt discovery degree
 857       true,                // atomic_discovery
 858       is_alive_non_header) {
 859   }
 860 
 861   template<typename T> bool discover(oop obj, ReferenceType type) {
 862     T* referent_addr = (T*) java_lang_ref_Reference::referent_addr_raw(obj);
 863     T heap_oop = RawAccess<>::oop_load(referent_addr);
 864     oop referent = CompressedOops::decode_not_null(heap_oop);
 865     return PSParallelCompact::mark_bitmap()->is_unmarked(referent)
 866         && ReferenceProcessor::discover_reference(obj, type);
 867   }
 868   virtual bool discover_reference(oop obj, ReferenceType type) {
 869     if (UseCompressedOops) {
 870       return discover<narrowOop>(obj, type);
 871     } else {
 872       return discover<oop>(obj, type);
 873     }
 874   }
 875 };
 876 
 877 void PSParallelCompact::post_initialize() {
 878   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
 879   _span_based_discoverer.set_span(heap->reserved_region());
 880   _ref_processor =
 881     new PCReferenceProcessor(&_span_based_discoverer,
 882                              &_is_alive_closure); // non-header is alive closure
 883 
 884   _counters = new CollectorCounters("Parallel full collection pauses", 1);
 885 
 886   // Initialize static fields in ParCompactionManager.
 887   ParCompactionManager::initialize(mark_bitmap());
 888 }
 889 
 890 bool PSParallelCompact::initialize() {
 891   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
 892   MemRegion mr = heap->reserved_region();
 893 
 894   // Was the old gen get allocated successfully?
 895   if (!heap->old_gen()->is_allocated()) {
 896     return false;
 897   }
 898 
 899   initialize_space_info();
 900   initialize_dead_wood_limiter();
 901 
 902   if (!_mark_bitmap.initialize(mr)) {
 903     vm_shutdown_during_initialization(
 904       err_msg("Unable to allocate " SIZE_FORMAT "KB bitmaps for parallel "
 905       "garbage collection for the requested " SIZE_FORMAT "KB heap.",
 906       _mark_bitmap.reserved_byte_size()/K, mr.byte_size()/K));
 907     return false;
 908   }
 909 
 910   if (!_summary_data.initialize(mr)) {
 911     vm_shutdown_during_initialization(
 912       err_msg("Unable to allocate " SIZE_FORMAT "KB card tables for parallel "
 913       "garbage collection for the requested " SIZE_FORMAT "KB heap.",
 914       _summary_data.reserved_byte_size()/K, mr.byte_size()/K));
 915     return false;
 916   }
 917 
 918   return true;
 919 }
 920 
 921 void PSParallelCompact::initialize_space_info()
 922 {
 923   memset(&_space_info, 0, sizeof(_space_info));
 924 
 925   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
 926   PSYoungGen* young_gen = heap->young_gen();
 927 
 928   _space_info[old_space_id].set_space(heap->old_gen()->object_space());
 929   _space_info[eden_space_id].set_space(young_gen->eden_space());
 930   _space_info[from_space_id].set_space(young_gen->from_space());
 931   _space_info[to_space_id].set_space(young_gen->to_space());
 932 
 933   _space_info[old_space_id].set_start_array(heap->old_gen()->start_array());
 934 }
 935 
 936 void PSParallelCompact::initialize_dead_wood_limiter()
 937 {
 938   const size_t max = 100;
 939   _dwl_mean = double(MIN2(ParallelOldDeadWoodLimiterMean, max)) / 100.0;
 940   _dwl_std_dev = double(MIN2(ParallelOldDeadWoodLimiterStdDev, max)) / 100.0;
 941   _dwl_first_term = 1.0 / (sqrt(2.0 * M_PI) * _dwl_std_dev);
 942   DEBUG_ONLY(_dwl_initialized = true;)
 943   _dwl_adjustment = normal_distribution(1.0);
 944 }
 945 
 946 void
 947 PSParallelCompact::clear_data_covering_space(SpaceId id)
 948 {
 949   // At this point, top is the value before GC, new_top() is the value that will
 950   // be set at the end of GC.  The marking bitmap is cleared to top; nothing
 951   // should be marked above top.  The summary data is cleared to the larger of
 952   // top & new_top.
 953   MutableSpace* const space = _space_info[id].space();
 954   HeapWord* const bot = space->bottom();
 955   HeapWord* const top = space->top();
 956   HeapWord* const max_top = MAX2(top, _space_info[id].new_top());
 957 
 958   const idx_t beg_bit = _mark_bitmap.addr_to_bit(bot);
 959   const idx_t end_bit = _mark_bitmap.align_range_end(_mark_bitmap.addr_to_bit(top));
 960   _mark_bitmap.clear_range(beg_bit, end_bit);
 961 
 962   const size_t beg_region = _summary_data.addr_to_region_idx(bot);
 963   const size_t end_region =
 964     _summary_data.addr_to_region_idx(_summary_data.region_align_up(max_top));
 965   _summary_data.clear_range(beg_region, end_region);
 966 
 967   // Clear the data used to 'split' regions.
 968   SplitInfo& split_info = _space_info[id].split_info();
 969   if (split_info.is_valid()) {
 970     split_info.clear();
 971   }
 972   DEBUG_ONLY(split_info.verify_clear();)
 973 }
 974 
 975 void PSParallelCompact::pre_compact()
 976 {
 977   // Update the from & to space pointers in space_info, since they are swapped
 978   // at each young gen gc.  Do the update unconditionally (even though a
 979   // promotion failure does not swap spaces) because an unknown number of young
 980   // collections will have swapped the spaces an unknown number of times.
 981   GCTraceTime(Debug, gc, phases) tm("Pre Compact", &_gc_timer);
 982   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
 983   _space_info[from_space_id].set_space(heap->young_gen()->from_space());
 984   _space_info[to_space_id].set_space(heap->young_gen()->to_space());
 985 
 986   // Increment the invocation count
 987   heap->increment_total_collections(true);
 988 
 989   // We need to track unique mark sweep invocations as well.
 990   _total_invocations++;
 991 
 992   heap->print_heap_before_gc();
 993   heap->trace_heap_before_gc(&_gc_tracer);
 994 
 995   // Fill in TLABs
 996   heap->ensure_parsability(true);  // retire TLABs
 997 
 998   if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
 999     Universe::verify("Before GC");
1000   }
1001 
1002   // Verify object start arrays
1003   if (VerifyObjectStartArray &&
1004       VerifyBeforeGC) {
1005     heap->old_gen()->verify_object_start_array();
1006   }
1007 
1008   DEBUG_ONLY(mark_bitmap()->verify_clear();)
1009   DEBUG_ONLY(summary_data().verify_clear();)
1010 
1011   ParCompactionManager::reset_all_bitmap_query_caches();
1012 }
1013 
1014 void PSParallelCompact::post_compact()
1015 {
1016   GCTraceTime(Info, gc, phases) tm("Post Compact", &_gc_timer);
1017   ParCompactionManager::remove_all_shadow_regions();
1018 
1019   for (unsigned int id = old_space_id; id < last_space_id; ++id) {
1020     // Clear the marking bitmap, summary data and split info.
1021     clear_data_covering_space(SpaceId(id));
1022     // Update top().  Must be done after clearing the bitmap and summary data.
1023     _space_info[id].publish_new_top();
1024   }
1025 
1026   ParCompactionManager::flush_all_string_dedup_requests();
1027 
1028   MutableSpace* const eden_space = _space_info[eden_space_id].space();
1029   MutableSpace* const from_space = _space_info[from_space_id].space();
1030   MutableSpace* const to_space   = _space_info[to_space_id].space();
1031 
1032   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
1033   bool eden_empty = eden_space->is_empty();
1034 
1035   // Update heap occupancy information which is used as input to the soft ref
1036   // clearing policy at the next gc.
1037   Universe::heap()->update_capacity_and_used_at_gc();
1038 
1039   bool young_gen_empty = eden_empty && from_space->is_empty() &&
1040     to_space->is_empty();
1041 
1042   PSCardTable* ct = heap->card_table();
1043   MemRegion old_mr = heap->old_gen()->reserved();
1044   if (young_gen_empty) {
1045     ct->clear(MemRegion(old_mr.start(), old_mr.end()));
1046   } else {
1047     ct->invalidate(MemRegion(old_mr.start(), old_mr.end()));
1048   }
1049 
1050   // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1051   ClassLoaderDataGraph::purge(/*at_safepoint*/true);
1052   DEBUG_ONLY(MetaspaceUtils::verify();)
1053 
1054   heap->prune_scavengable_nmethods();
1055 
1056 #if COMPILER2_OR_JVMCI
1057   DerivedPointerTable::update_pointers();
1058 #endif
1059 
1060   if (ZapUnusedHeapArea) {
1061     heap->gen_mangle_unused_area();
1062   }
1063 
1064   // Signal that we have completed a visit to all live objects.
1065   Universe::heap()->record_whole_heap_examined_timestamp();
1066 }
1067 
1068 HeapWord*
1069 PSParallelCompact::compute_dense_prefix_via_density(const SpaceId id,
1070                                                     bool maximum_compaction)
1071 {
1072   const size_t region_size = ParallelCompactData::RegionSize;
1073   const ParallelCompactData& sd = summary_data();
1074 
1075   const MutableSpace* const space = _space_info[id].space();
1076   HeapWord* const top_aligned_up = sd.region_align_up(space->top());
1077   const RegionData* const beg_cp = sd.addr_to_region_ptr(space->bottom());
1078   const RegionData* const end_cp = sd.addr_to_region_ptr(top_aligned_up);
1079 
1080   // Skip full regions at the beginning of the space--they are necessarily part
1081   // of the dense prefix.
1082   size_t full_count = 0;
1083   const RegionData* cp;
1084   for (cp = beg_cp; cp < end_cp && cp->data_size() == region_size; ++cp) {
1085     ++full_count;
1086   }
1087 
1088   assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");
1089   const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;
1090   const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval;
1091   if (maximum_compaction || cp == end_cp || interval_ended) {
1092     _maximum_compaction_gc_num = total_invocations();
1093     return sd.region_to_addr(cp);
1094   }
1095 
1096   HeapWord* const new_top = _space_info[id].new_top();
1097   const size_t space_live = pointer_delta(new_top, space->bottom());
1098   const size_t space_used = space->used_in_words();
1099   const size_t space_capacity = space->capacity_in_words();
1100 
1101   const double cur_density = double(space_live) / space_capacity;
1102   const double deadwood_density =
1103     (1.0 - cur_density) * (1.0 - cur_density) * cur_density * cur_density;
1104   const size_t deadwood_goal = size_t(space_capacity * deadwood_density);
1105 
1106   log_develop_debug(gc, compaction)(
1107       "cur_dens=%5.3f dw_dens=%5.3f dw_goal=" SIZE_FORMAT,
1108       cur_density, deadwood_density, deadwood_goal);
1109   log_develop_debug(gc, compaction)(
1110       "space_live=" SIZE_FORMAT " space_used=" SIZE_FORMAT " "
1111       "space_cap=" SIZE_FORMAT,
1112       space_live, space_used,
1113       space_capacity);
1114 
1115   // XXX - Use binary search?
1116   HeapWord* dense_prefix = sd.region_to_addr(cp);
1117   const RegionData* full_cp = cp;
1118   const RegionData* const top_cp = sd.addr_to_region_ptr(space->top() - 1);
1119   while (cp < end_cp) {
1120     HeapWord* region_destination = cp->destination();
1121     const size_t cur_deadwood = pointer_delta(dense_prefix, region_destination);
1122 
1123     log_develop_trace(gc, compaction)(
1124         "c#=" SIZE_FORMAT_W(4) " dst=" PTR_FORMAT " "
1125         "dp=" PTR_FORMAT " cdw=" SIZE_FORMAT_W(8),
1126         sd.region(cp), p2i(region_destination),
1127         p2i(dense_prefix), cur_deadwood);
1128 
1129     if (cur_deadwood >= deadwood_goal) {
1130       // Found the region that has the correct amount of deadwood to the left.
1131       // This typically occurs after crossing a fairly sparse set of regions, so
1132       // iterate backwards over those sparse regions, looking for the region
1133       // that has the lowest density of live objects 'to the right.'
1134       size_t space_to_left = sd.region(cp) * region_size;
1135       size_t live_to_left = space_to_left - cur_deadwood;
1136       size_t space_to_right = space_capacity - space_to_left;
1137       size_t live_to_right = space_live - live_to_left;
1138       double density_to_right = double(live_to_right) / space_to_right;
1139       while (cp > full_cp) {
1140         --cp;
1141         const size_t prev_region_live_to_right = live_to_right -
1142           cp->data_size();
1143         const size_t prev_region_space_to_right = space_to_right + region_size;
1144         double prev_region_density_to_right =
1145           double(prev_region_live_to_right) / prev_region_space_to_right;
1146         if (density_to_right <= prev_region_density_to_right) {
1147           return dense_prefix;
1148         }
1149 
1150         log_develop_trace(gc, compaction)(
1151             "backing up from c=" SIZE_FORMAT_W(4) " d2r=%10.8f "
1152             "pc_d2r=%10.8f",
1153             sd.region(cp), density_to_right,
1154             prev_region_density_to_right);
1155 
1156         dense_prefix -= region_size;
1157         live_to_right = prev_region_live_to_right;
1158         space_to_right = prev_region_space_to_right;
1159         density_to_right = prev_region_density_to_right;
1160       }
1161       return dense_prefix;
1162     }
1163 
1164     dense_prefix += region_size;
1165     ++cp;
1166   }
1167 
1168   return dense_prefix;
1169 }
1170 
1171 #ifndef PRODUCT
1172 void PSParallelCompact::print_dense_prefix_stats(const char* const algorithm,
1173                                                  const SpaceId id,
1174                                                  const bool maximum_compaction,
1175                                                  HeapWord* const addr)
1176 {
1177   const size_t region_idx = summary_data().addr_to_region_idx(addr);
1178   RegionData* const cp = summary_data().region(region_idx);
1179   const MutableSpace* const space = _space_info[id].space();
1180   HeapWord* const new_top = _space_info[id].new_top();
1181 
1182   const size_t space_live = pointer_delta(new_top, space->bottom());
1183   const size_t dead_to_left = pointer_delta(addr, cp->destination());
1184   const size_t space_cap = space->capacity_in_words();
1185   const double dead_to_left_pct = double(dead_to_left) / space_cap;
1186   const size_t live_to_right = new_top - cp->destination();
1187   const size_t dead_to_right = space->top() - addr - live_to_right;
1188 
1189   log_develop_debug(gc, compaction)(
1190       "%s=" PTR_FORMAT " dpc=" SIZE_FORMAT_W(5) " "
1191       "spl=" SIZE_FORMAT " "
1192       "d2l=" SIZE_FORMAT " d2l%%=%6.4f "
1193       "d2r=" SIZE_FORMAT " l2r=" SIZE_FORMAT " "
1194       "ratio=%10.8f",
1195       algorithm, p2i(addr), region_idx,
1196       space_live,
1197       dead_to_left, dead_to_left_pct,
1198       dead_to_right, live_to_right,
1199       double(dead_to_right) / live_to_right);
1200 }
1201 #endif  // #ifndef PRODUCT
1202 
1203 // Return a fraction indicating how much of the generation can be treated as
1204 // "dead wood" (i.e., not reclaimed).  The function uses a normal distribution
1205 // based on the density of live objects in the generation to determine a limit,
1206 // which is then adjusted so the return value is min_percent when the density is
1207 // 1.
1208 //
1209 // The following table shows some return values for a different values of the
1210 // standard deviation (ParallelOldDeadWoodLimiterStdDev); the mean is 0.5 and
1211 // min_percent is 1.
1212 //
1213 //                          fraction allowed as dead wood
1214 //         -----------------------------------------------------------------
1215 // density std_dev=70 std_dev=75 std_dev=80 std_dev=85 std_dev=90 std_dev=95
1216 // ------- ---------- ---------- ---------- ---------- ---------- ----------
1217 // 0.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
1218 // 0.05000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
1219 // 0.10000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
1220 // 0.15000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
1221 // 0.20000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
1222 // 0.25000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
1223 // 0.30000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
1224 // 0.35000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
1225 // 0.40000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
1226 // 0.45000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
1227 // 0.50000 0.13832410 0.11599237 0.09847664 0.08456518 0.07338887 0.06431510
1228 // 0.55000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
1229 // 0.60000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
1230 // 0.65000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
1231 // 0.70000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
1232 // 0.75000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
1233 // 0.80000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
1234 // 0.85000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
1235 // 0.90000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
1236 // 0.95000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
1237 // 1.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
1238 
1239 double PSParallelCompact::dead_wood_limiter(double density, size_t min_percent)
1240 {
1241   assert(_dwl_initialized, "uninitialized");
1242 
1243   // The raw limit is the value of the normal distribution at x = density.
1244   const double raw_limit = normal_distribution(density);
1245 
1246   // Adjust the raw limit so it becomes the minimum when the density is 1.
1247   //
1248   // First subtract the adjustment value (which is simply the precomputed value
1249   // normal_distribution(1.0)); this yields a value of 0 when the density is 1.
1250   // Then add the minimum value, so the minimum is returned when the density is
1251   // 1.  Finally, prevent negative values, which occur when the mean is not 0.5.
1252   const double min = double(min_percent) / 100.0;
1253   const double limit = raw_limit - _dwl_adjustment + min;
1254   return MAX2(limit, 0.0);
1255 }
1256 
1257 ParallelCompactData::RegionData*
1258 PSParallelCompact::first_dead_space_region(const RegionData* beg,
1259                                            const RegionData* end)
1260 {
1261   const size_t region_size = ParallelCompactData::RegionSize;
1262   ParallelCompactData& sd = summary_data();
1263   size_t left = sd.region(beg);
1264   size_t right = end > beg ? sd.region(end) - 1 : left;
1265 
1266   // Binary search.
1267   while (left < right) {
1268     // Equivalent to (left + right) / 2, but does not overflow.
1269     const size_t middle = left + (right - left) / 2;
1270     RegionData* const middle_ptr = sd.region(middle);
1271     HeapWord* const dest = middle_ptr->destination();
1272     HeapWord* const addr = sd.region_to_addr(middle);
1273     assert(dest != NULL, "sanity");
1274     assert(dest <= addr, "must move left");
1275 
1276     if (middle > left && dest < addr) {
1277       right = middle - 1;
1278     } else if (middle < right && middle_ptr->data_size() == region_size) {
1279       left = middle + 1;
1280     } else {
1281       return middle_ptr;
1282     }
1283   }
1284   return sd.region(left);
1285 }
1286 
1287 ParallelCompactData::RegionData*
1288 PSParallelCompact::dead_wood_limit_region(const RegionData* beg,
1289                                           const RegionData* end,
1290                                           size_t dead_words)
1291 {
1292   ParallelCompactData& sd = summary_data();
1293   size_t left = sd.region(beg);
1294   size_t right = end > beg ? sd.region(end) - 1 : left;
1295 
1296   // Binary search.
1297   while (left < right) {
1298     // Equivalent to (left + right) / 2, but does not overflow.
1299     const size_t middle = left + (right - left) / 2;
1300     RegionData* const middle_ptr = sd.region(middle);
1301     HeapWord* const dest = middle_ptr->destination();
1302     HeapWord* const addr = sd.region_to_addr(middle);
1303     assert(dest != NULL, "sanity");
1304     assert(dest <= addr, "must move left");
1305 
1306     const size_t dead_to_left = pointer_delta(addr, dest);
1307     if (middle > left && dead_to_left > dead_words) {
1308       right = middle - 1;
1309     } else if (middle < right && dead_to_left < dead_words) {
1310       left = middle + 1;
1311     } else {
1312       return middle_ptr;
1313     }
1314   }
1315   return sd.region(left);
1316 }
1317 
1318 // The result is valid during the summary phase, after the initial summarization
1319 // of each space into itself, and before final summarization.
1320 inline double
1321 PSParallelCompact::reclaimed_ratio(const RegionData* const cp,
1322                                    HeapWord* const bottom,
1323                                    HeapWord* const top,
1324                                    HeapWord* const new_top)
1325 {
1326   ParallelCompactData& sd = summary_data();
1327 
1328   assert(cp != NULL, "sanity");
1329   assert(bottom != NULL, "sanity");
1330   assert(top != NULL, "sanity");
1331   assert(new_top != NULL, "sanity");
1332   assert(top >= new_top, "summary data problem?");
1333   assert(new_top > bottom, "space is empty; should not be here");
1334   assert(new_top >= cp->destination(), "sanity");
1335   assert(top >= sd.region_to_addr(cp), "sanity");
1336 
1337   HeapWord* const destination = cp->destination();
1338   const size_t dense_prefix_live  = pointer_delta(destination, bottom);
1339   const size_t compacted_region_live = pointer_delta(new_top, destination);
1340   const size_t compacted_region_used = pointer_delta(top,
1341                                                      sd.region_to_addr(cp));
1342   const size_t reclaimable = compacted_region_used - compacted_region_live;
1343 
1344   const double divisor = dense_prefix_live + 1.25 * compacted_region_live;
1345   return double(reclaimable) / divisor;
1346 }
1347 
1348 // Return the address of the end of the dense prefix, a.k.a. the start of the
1349 // compacted region.  The address is always on a region boundary.
1350 //
1351 // Completely full regions at the left are skipped, since no compaction can
1352 // occur in those regions.  Then the maximum amount of dead wood to allow is
1353 // computed, based on the density (amount live / capacity) of the generation;
1354 // the region with approximately that amount of dead space to the left is
1355 // identified as the limit region.  Regions between the last completely full
1356 // region and the limit region are scanned and the one that has the best
1357 // (maximum) reclaimed_ratio() is selected.
1358 HeapWord*
1359 PSParallelCompact::compute_dense_prefix(const SpaceId id,
1360                                         bool maximum_compaction)
1361 {
1362   const size_t region_size = ParallelCompactData::RegionSize;
1363   const ParallelCompactData& sd = summary_data();
1364 
1365   const MutableSpace* const space = _space_info[id].space();
1366   HeapWord* const top = space->top();
1367   HeapWord* const top_aligned_up = sd.region_align_up(top);
1368   HeapWord* const new_top = _space_info[id].new_top();
1369   HeapWord* const new_top_aligned_up = sd.region_align_up(new_top);
1370   HeapWord* const bottom = space->bottom();
1371   const RegionData* const beg_cp = sd.addr_to_region_ptr(bottom);
1372   const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
1373   const RegionData* const new_top_cp =
1374     sd.addr_to_region_ptr(new_top_aligned_up);
1375 
1376   // Skip full regions at the beginning of the space--they are necessarily part
1377   // of the dense prefix.
1378   const RegionData* const full_cp = first_dead_space_region(beg_cp, new_top_cp);
1379   assert(full_cp->destination() == sd.region_to_addr(full_cp) ||
1380          space->is_empty(), "no dead space allowed to the left");
1381   assert(full_cp->data_size() < region_size || full_cp == new_top_cp - 1,
1382          "region must have dead space");
1383 
1384   // The gc number is saved whenever a maximum compaction is done, and used to
1385   // determine when the maximum compaction interval has expired.  This avoids
1386   // successive max compactions for different reasons.
1387   assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");
1388   const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;
1389   const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval ||
1390     total_invocations() == HeapFirstMaximumCompactionCount;
1391   if (maximum_compaction || full_cp == top_cp || interval_ended) {
1392     _maximum_compaction_gc_num = total_invocations();
1393     return sd.region_to_addr(full_cp);
1394   }
1395 
1396   const size_t space_live = pointer_delta(new_top, bottom);
1397   const size_t space_used = space->used_in_words();
1398   const size_t space_capacity = space->capacity_in_words();
1399 
1400   const double density = double(space_live) / double(space_capacity);
1401   const size_t min_percent_free = MarkSweepDeadRatio;
1402   const double limiter = dead_wood_limiter(density, min_percent_free);
1403   const size_t dead_wood_max = space_used - space_live;
1404   const size_t dead_wood_limit = MIN2(size_t(space_capacity * limiter),
1405                                       dead_wood_max);
1406 
1407   log_develop_debug(gc, compaction)(
1408       "space_live=" SIZE_FORMAT " space_used=" SIZE_FORMAT " "
1409       "space_cap=" SIZE_FORMAT,
1410       space_live, space_used,
1411       space_capacity);
1412   log_develop_debug(gc, compaction)(
1413       "dead_wood_limiter(%6.4f, " SIZE_FORMAT ")=%6.4f "
1414       "dead_wood_max=" SIZE_FORMAT " dead_wood_limit=" SIZE_FORMAT,
1415       density, min_percent_free, limiter,
1416       dead_wood_max, dead_wood_limit);
1417 
1418   // Locate the region with the desired amount of dead space to the left.
1419   const RegionData* const limit_cp =
1420     dead_wood_limit_region(full_cp, top_cp, dead_wood_limit);
1421 
1422   // Scan from the first region with dead space to the limit region and find the
1423   // one with the best (largest) reclaimed ratio.
1424   double best_ratio = 0.0;
1425   const RegionData* best_cp = full_cp;
1426   for (const RegionData* cp = full_cp; cp < limit_cp; ++cp) {
1427     double tmp_ratio = reclaimed_ratio(cp, bottom, top, new_top);
1428     if (tmp_ratio > best_ratio) {
1429       best_cp = cp;
1430       best_ratio = tmp_ratio;
1431     }
1432   }
1433 
1434   return sd.region_to_addr(best_cp);
1435 }
1436 
1437 void PSParallelCompact::summarize_spaces_quick()
1438 {
1439   for (unsigned int i = 0; i < last_space_id; ++i) {
1440     const MutableSpace* space = _space_info[i].space();
1441     HeapWord** nta = _space_info[i].new_top_addr();
1442     bool result = _summary_data.summarize(_space_info[i].split_info(),
1443                                           space->bottom(), space->top(), NULL,
1444                                           space->bottom(), space->end(), nta);
1445     assert(result, "space must fit into itself");
1446     _space_info[i].set_dense_prefix(space->bottom());
1447   }
1448 }
1449 
1450 void PSParallelCompact::fill_dense_prefix_end(SpaceId id)
1451 {
1452   HeapWord* const dense_prefix_end = dense_prefix(id);
1453   const RegionData* region = _summary_data.addr_to_region_ptr(dense_prefix_end);
1454   const idx_t dense_prefix_bit = _mark_bitmap.addr_to_bit(dense_prefix_end);
1455   if (dead_space_crosses_boundary(region, dense_prefix_bit)) {
1456     // Only enough dead space is filled so that any remaining dead space to the
1457     // left is larger than the minimum filler object.  (The remainder is filled
1458     // during the copy/update phase.)
1459     //
1460     // The size of the dead space to the right of the boundary is not a
1461     // concern, since compaction will be able to use whatever space is
1462     // available.
1463     //
1464     // Here '||' is the boundary, 'x' represents a don't care bit and a box
1465     // surrounds the space to be filled with an object.
1466     //
1467     // In the 32-bit VM, each bit represents two 32-bit words:
1468     //                              +---+
1469     // a) beg_bits:  ...  x   x   x | 0 | ||   0   x  x  ...
1470     //    end_bits:  ...  x   x   x | 0 | ||   0   x  x  ...
1471     //                              +---+
1472     //
1473     // In the 64-bit VM, each bit represents one 64-bit word:
1474     //                              +------------+
1475     // b) beg_bits:  ...  x   x   x | 0   ||   0 | x  x  ...
1476     //    end_bits:  ...  x   x   1 | 0   ||   0 | x  x  ...
1477     //                              +------------+
1478     //                          +-------+
1479     // c) beg_bits:  ...  x   x | 0   0 | ||   0   x  x  ...
1480     //    end_bits:  ...  x   1 | 0   0 | ||   0   x  x  ...
1481     //                          +-------+
1482     //                      +-----------+
1483     // d) beg_bits:  ...  x | 0   0   0 | ||   0   x  x  ...
1484     //    end_bits:  ...  1 | 0   0   0 | ||   0   x  x  ...
1485     //                      +-----------+
1486     //                          +-------+
1487     // e) beg_bits:  ...  0   0 | 0   0 | ||   0   x  x  ...
1488     //    end_bits:  ...  0   0 | 0   0 | ||   0   x  x  ...
1489     //                          +-------+
1490 
1491     // Initially assume case a, c or e will apply.
1492     size_t obj_len = CollectedHeap::min_fill_size();
1493     HeapWord* obj_beg = dense_prefix_end - obj_len;
1494 
1495 #ifdef  _LP64
1496     if (MinObjAlignment > 1) { // object alignment > heap word size
1497       // Cases a, c or e.
1498     } else if (_mark_bitmap.is_obj_end(dense_prefix_bit - 2)) {
1499       // Case b above.
1500       obj_beg = dense_prefix_end - 1;
1501     } else if (!_mark_bitmap.is_obj_end(dense_prefix_bit - 3) &&
1502                _mark_bitmap.is_obj_end(dense_prefix_bit - 4)) {
1503       // Case d above.
1504       obj_beg = dense_prefix_end - 3;
1505       obj_len = 3;
1506     }
1507 #endif  // #ifdef _LP64
1508 
1509     CollectedHeap::fill_with_object(obj_beg, obj_len);
1510     _mark_bitmap.mark_obj(obj_beg, obj_len);
1511     _summary_data.add_obj(obj_beg, obj_len);
1512     assert(start_array(id) != NULL, "sanity");
1513     start_array(id)->allocate_block(obj_beg);
1514   }
1515 }
1516 
1517 void
1518 PSParallelCompact::summarize_space(SpaceId id, bool maximum_compaction)
1519 {
1520   assert(id < last_space_id, "id out of range");
1521   assert(_space_info[id].dense_prefix() == _space_info[id].space()->bottom(),
1522          "should have been reset in summarize_spaces_quick()");
1523 
1524   const MutableSpace* space = _space_info[id].space();
1525   if (_space_info[id].new_top() != space->bottom()) {
1526     HeapWord* dense_prefix_end = compute_dense_prefix(id, maximum_compaction);
1527     _space_info[id].set_dense_prefix(dense_prefix_end);
1528 
1529 #ifndef PRODUCT
1530     if (log_is_enabled(Debug, gc, compaction)) {
1531       print_dense_prefix_stats("ratio", id, maximum_compaction,
1532                                dense_prefix_end);
1533       HeapWord* addr = compute_dense_prefix_via_density(id, maximum_compaction);
1534       print_dense_prefix_stats("density", id, maximum_compaction, addr);
1535     }
1536 #endif  // #ifndef PRODUCT
1537 
1538     // Recompute the summary data, taking into account the dense prefix.  If
1539     // every last byte will be reclaimed, then the existing summary data which
1540     // compacts everything can be left in place.
1541     if (!maximum_compaction && dense_prefix_end != space->bottom()) {
1542       // If dead space crosses the dense prefix boundary, it is (at least
1543       // partially) filled with a dummy object, marked live and added to the
1544       // summary data.  This simplifies the copy/update phase and must be done
1545       // before the final locations of objects are determined, to prevent
1546       // leaving a fragment of dead space that is too small to fill.
1547       fill_dense_prefix_end(id);
1548 
1549       // Compute the destination of each Region, and thus each object.
1550       _summary_data.summarize_dense_prefix(space->bottom(), dense_prefix_end);
1551       _summary_data.summarize(_space_info[id].split_info(),
1552                               dense_prefix_end, space->top(), NULL,
1553                               dense_prefix_end, space->end(),
1554                               _space_info[id].new_top_addr());
1555     }
1556   }
1557 
1558   if (log_develop_is_enabled(Trace, gc, compaction)) {
1559     const size_t region_size = ParallelCompactData::RegionSize;
1560     HeapWord* const dense_prefix_end = _space_info[id].dense_prefix();
1561     const size_t dp_region = _summary_data.addr_to_region_idx(dense_prefix_end);
1562     const size_t dp_words = pointer_delta(dense_prefix_end, space->bottom());
1563     HeapWord* const new_top = _space_info[id].new_top();
1564     const HeapWord* nt_aligned_up = _summary_data.region_align_up(new_top);
1565     const size_t cr_words = pointer_delta(nt_aligned_up, dense_prefix_end);
1566     log_develop_trace(gc, compaction)(
1567         "id=%d cap=" SIZE_FORMAT " dp=" PTR_FORMAT " "
1568         "dp_region=" SIZE_FORMAT " " "dp_count=" SIZE_FORMAT " "
1569         "cr_count=" SIZE_FORMAT " " "nt=" PTR_FORMAT,
1570         id, space->capacity_in_words(), p2i(dense_prefix_end),
1571         dp_region, dp_words / region_size,
1572         cr_words / region_size, p2i(new_top));
1573   }
1574 }
1575 
1576 #ifndef PRODUCT
1577 void PSParallelCompact::summary_phase_msg(SpaceId dst_space_id,
1578                                           HeapWord* dst_beg, HeapWord* dst_end,
1579                                           SpaceId src_space_id,
1580                                           HeapWord* src_beg, HeapWord* src_end)
1581 {
1582   log_develop_trace(gc, compaction)(
1583       "Summarizing %d [%s] into %d [%s]:  "
1584       "src=" PTR_FORMAT "-" PTR_FORMAT " "
1585       SIZE_FORMAT "-" SIZE_FORMAT " "
1586       "dst=" PTR_FORMAT "-" PTR_FORMAT " "
1587       SIZE_FORMAT "-" SIZE_FORMAT,
1588       src_space_id, space_names[src_space_id],
1589       dst_space_id, space_names[dst_space_id],
1590       p2i(src_beg), p2i(src_end),
1591       _summary_data.addr_to_region_idx(src_beg),
1592       _summary_data.addr_to_region_idx(src_end),
1593       p2i(dst_beg), p2i(dst_end),
1594       _summary_data.addr_to_region_idx(dst_beg),
1595       _summary_data.addr_to_region_idx(dst_end));
1596 }
1597 #endif  // #ifndef PRODUCT
1598 
1599 void PSParallelCompact::summary_phase(ParCompactionManager* cm,
1600                                       bool maximum_compaction)
1601 {
1602   GCTraceTime(Info, gc, phases) tm("Summary Phase", &_gc_timer);
1603 
1604   // Quick summarization of each space into itself, to see how much is live.
1605   summarize_spaces_quick();
1606 
1607   log_develop_trace(gc, compaction)("summary phase:  after summarizing each space to self");
1608   NOT_PRODUCT(print_region_ranges());
1609   NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info));
1610 
1611   // The amount of live data that will end up in old space (assuming it fits).
1612   size_t old_space_total_live = 0;
1613   for (unsigned int id = old_space_id; id < last_space_id; ++id) {
1614     old_space_total_live += pointer_delta(_space_info[id].new_top(),
1615                                           _space_info[id].space()->bottom());
1616   }
1617 
1618   MutableSpace* const old_space = _space_info[old_space_id].space();
1619   const size_t old_capacity = old_space->capacity_in_words();
1620   if (old_space_total_live > old_capacity) {
1621     // XXX - should also try to expand
1622     maximum_compaction = true;
1623   }
1624 
1625   // Old generations.
1626   summarize_space(old_space_id, maximum_compaction);
1627 
1628   // Summarize the remaining spaces in the young gen.  The initial target space
1629   // is the old gen.  If a space does not fit entirely into the target, then the
1630   // remainder is compacted into the space itself and that space becomes the new
1631   // target.
1632   SpaceId dst_space_id = old_space_id;
1633   HeapWord* dst_space_end = old_space->end();
1634   HeapWord** new_top_addr = _space_info[dst_space_id].new_top_addr();
1635   for (unsigned int id = eden_space_id; id < last_space_id; ++id) {
1636     const MutableSpace* space = _space_info[id].space();
1637     const size_t live = pointer_delta(_space_info[id].new_top(),
1638                                       space->bottom());
1639     const size_t available = pointer_delta(dst_space_end, *new_top_addr);
1640 
1641     NOT_PRODUCT(summary_phase_msg(dst_space_id, *new_top_addr, dst_space_end,
1642                                   SpaceId(id), space->bottom(), space->top());)
1643     if (live > 0 && live <= available) {
1644       // All the live data will fit.
1645       bool done = _summary_data.summarize(_space_info[id].split_info(),
1646                                           space->bottom(), space->top(),
1647                                           NULL,
1648                                           *new_top_addr, dst_space_end,
1649                                           new_top_addr);
1650       assert(done, "space must fit into old gen");
1651 
1652       // Reset the new_top value for the space.
1653       _space_info[id].set_new_top(space->bottom());
1654     } else if (live > 0) {
1655       // Attempt to fit part of the source space into the target space.
1656       HeapWord* next_src_addr = NULL;
1657       bool done = _summary_data.summarize(_space_info[id].split_info(),
1658                                           space->bottom(), space->top(),
1659                                           &next_src_addr,
1660                                           *new_top_addr, dst_space_end,
1661                                           new_top_addr);
1662       assert(!done, "space should not fit into old gen");
1663       assert(next_src_addr != NULL, "sanity");
1664 
1665       // The source space becomes the new target, so the remainder is compacted
1666       // within the space itself.
1667       dst_space_id = SpaceId(id);
1668       dst_space_end = space->end();
1669       new_top_addr = _space_info[id].new_top_addr();
1670       NOT_PRODUCT(summary_phase_msg(dst_space_id,
1671                                     space->bottom(), dst_space_end,
1672                                     SpaceId(id), next_src_addr, space->top());)
1673       done = _summary_data.summarize(_space_info[id].split_info(),
1674                                      next_src_addr, space->top(),
1675                                      NULL,
1676                                      space->bottom(), dst_space_end,
1677                                      new_top_addr);
1678       assert(done, "space must fit when compacted into itself");
1679       assert(*new_top_addr <= space->top(), "usage should not grow");
1680     }
1681   }
1682 
1683   log_develop_trace(gc, compaction)("Summary_phase:  after final summarization");
1684   NOT_PRODUCT(print_region_ranges());
1685   NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info));
1686 }
1687 
1688 // This method should contain all heap-specific policy for invoking a full
1689 // collection.  invoke_no_policy() will only attempt to compact the heap; it
1690 // will do nothing further.  If we need to bail out for policy reasons, scavenge
1691 // before full gc, or any other specialized behavior, it needs to be added here.
1692 //
1693 // Note that this method should only be called from the vm_thread while at a
1694 // safepoint.
1695 //
1696 // Note that the all_soft_refs_clear flag in the soft ref policy
1697 // may be true because this method can be called without intervening
1698 // activity.  For example when the heap space is tight and full measure
1699 // are being taken to free space.
1700 void PSParallelCompact::invoke(bool maximum_heap_compaction) {
1701   assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
1702   assert(Thread::current() == (Thread*)VMThread::vm_thread(),
1703          "should be in vm thread");
1704 
1705   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
1706   GCCause::Cause gc_cause = heap->gc_cause();
1707   assert(!heap->is_gc_active(), "not reentrant");
1708 
1709   PSAdaptiveSizePolicy* policy = heap->size_policy();
1710   IsGCActiveMark mark;
1711 
1712   if (ScavengeBeforeFullGC) {
1713     PSScavenge::invoke_no_policy();
1714   }
1715 
1716   const bool clear_all_soft_refs =
1717     heap->soft_ref_policy()->should_clear_all_soft_refs();
1718 
1719   PSParallelCompact::invoke_no_policy(clear_all_soft_refs ||
1720                                       maximum_heap_compaction);
1721 }
1722 
1723 // This method contains no policy. You should probably
1724 // be calling invoke() instead.
1725 bool PSParallelCompact::invoke_no_policy(bool maximum_heap_compaction) {
1726   assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
1727   assert(ref_processor() != NULL, "Sanity");
1728 
1729   if (GCLocker::check_active_before_gc()) {
1730     return false;
1731   }
1732 
1733   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
1734 
1735   GCIdMark gc_id_mark;
1736   _gc_timer.register_gc_start();
1737   _gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start());
1738 
1739   TimeStamp marking_start;
1740   TimeStamp compaction_start;
1741   TimeStamp collection_exit;
1742 
1743   GCCause::Cause gc_cause = heap->gc_cause();
1744   PSYoungGen* young_gen = heap->young_gen();
1745   PSOldGen* old_gen = heap->old_gen();
1746   PSAdaptiveSizePolicy* size_policy = heap->size_policy();
1747 
1748   // The scope of casr should end after code that can change
1749   // SoftRefPolicy::_should_clear_all_soft_refs.
1750   ClearedAllSoftRefs casr(maximum_heap_compaction,
1751                           heap->soft_ref_policy());
1752 
1753   if (ZapUnusedHeapArea) {
1754     // Save information needed to minimize mangling
1755     heap->record_gen_tops_before_GC();
1756   }
1757 
1758   // Make sure data structures are sane, make the heap parsable, and do other
1759   // miscellaneous bookkeeping.
1760   pre_compact();
1761 
1762   const PreGenGCValues pre_gc_values = heap->get_pre_gc_values();
1763 
1764   // Get the compaction manager reserved for the VM thread.
1765   ParCompactionManager* const vmthread_cm = ParCompactionManager::get_vmthread_cm();
1766 
1767   {
1768     const uint active_workers =
1769       WorkerPolicy::calc_active_workers(ParallelScavengeHeap::heap()->workers().total_workers(),
1770                                         ParallelScavengeHeap::heap()->workers().active_workers(),
1771                                         Threads::number_of_non_daemon_threads());
1772     ParallelScavengeHeap::heap()->workers().update_active_workers(active_workers);
1773 
1774     GCTraceCPUTime tcpu;
1775     GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause, true);
1776 
1777     heap->pre_full_gc_dump(&_gc_timer);
1778 
1779     TraceCollectorStats tcs(counters());
1780     TraceMemoryManagerStats tms(heap->old_gc_manager(), gc_cause);
1781 
1782     if (log_is_enabled(Debug, gc, heap, exit)) {
1783       accumulated_time()->start();
1784     }
1785 
1786     // Let the size policy know we're starting
1787     size_policy->major_collection_begin();
1788 
1789 #if COMPILER2_OR_JVMCI
1790     DerivedPointerTable::clear();
1791 #endif
1792 
1793     ref_processor()->start_discovery(maximum_heap_compaction);
1794 
1795     marking_start.update();
1796     marking_phase(vmthread_cm, &_gc_tracer);
1797 
1798     bool max_on_system_gc = UseMaximumCompactionOnSystemGC
1799       && GCCause::is_user_requested_gc(gc_cause);
1800     summary_phase(vmthread_cm, maximum_heap_compaction || max_on_system_gc);
1801 
1802 #if COMPILER2_OR_JVMCI
1803     assert(DerivedPointerTable::is_active(), "Sanity");
1804     DerivedPointerTable::set_active(false);
1805 #endif
1806 
1807     // adjust_roots() updates Universe::_intArrayKlassObj which is
1808     // needed by the compaction for filling holes in the dense prefix.
1809     adjust_roots();
1810 
1811     compaction_start.update();
1812     compact();
1813 
1814     ParCompactionManager::verify_all_region_stack_empty();
1815 
1816     // Reset the mark bitmap, summary data, and do other bookkeeping.  Must be
1817     // done before resizing.
1818     post_compact();
1819 
1820     // Let the size policy know we're done
1821     size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause);
1822 
1823     if (UseAdaptiveSizePolicy) {
1824       log_debug(gc, ergo)("AdaptiveSizeStart: collection: %d ", heap->total_collections());
1825       log_trace(gc, ergo)("old_gen_capacity: " SIZE_FORMAT " young_gen_capacity: " SIZE_FORMAT,
1826                           old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes());
1827 
1828       // Don't check if the size_policy is ready here.  Let
1829       // the size_policy check that internally.
1830       if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&
1831           AdaptiveSizePolicy::should_update_promo_stats(gc_cause)) {
1832         // Swap the survivor spaces if from_space is empty. The
1833         // resize_young_gen() called below is normally used after
1834         // a successful young GC and swapping of survivor spaces;
1835         // otherwise, it will fail to resize the young gen with
1836         // the current implementation.
1837         if (young_gen->from_space()->is_empty()) {
1838           young_gen->from_space()->clear(SpaceDecorator::Mangle);
1839           young_gen->swap_spaces();
1840         }
1841 
1842         // Calculate optimal free space amounts
1843         assert(young_gen->max_gen_size() >
1844           young_gen->from_space()->capacity_in_bytes() +
1845           young_gen->to_space()->capacity_in_bytes(),
1846           "Sizes of space in young gen are out-of-bounds");
1847 
1848         size_t young_live = young_gen->used_in_bytes();
1849         size_t eden_live = young_gen->eden_space()->used_in_bytes();
1850         size_t old_live = old_gen->used_in_bytes();
1851         size_t cur_eden = young_gen->eden_space()->capacity_in_bytes();
1852         size_t max_old_gen_size = old_gen->max_gen_size();
1853         size_t max_eden_size = young_gen->max_gen_size() -
1854           young_gen->from_space()->capacity_in_bytes() -
1855           young_gen->to_space()->capacity_in_bytes();
1856 
1857         // Used for diagnostics
1858         size_policy->clear_generation_free_space_flags();
1859 
1860         size_policy->compute_generations_free_space(young_live,
1861                                                     eden_live,
1862                                                     old_live,
1863                                                     cur_eden,
1864                                                     max_old_gen_size,
1865                                                     max_eden_size,
1866                                                     true /* full gc*/);
1867 
1868         size_policy->check_gc_overhead_limit(eden_live,
1869                                              max_old_gen_size,
1870                                              max_eden_size,
1871                                              true /* full gc*/,
1872                                              gc_cause,
1873                                              heap->soft_ref_policy());
1874 
1875         size_policy->decay_supplemental_growth(true /* full gc*/);
1876 
1877         heap->resize_old_gen(
1878           size_policy->calculated_old_free_size_in_bytes());
1879 
1880         heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(),
1881                                size_policy->calculated_survivor_size_in_bytes());
1882       }
1883 
1884       log_debug(gc, ergo)("AdaptiveSizeStop: collection: %d ", heap->total_collections());
1885     }
1886 
1887     if (UsePerfData) {
1888       PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters();
1889       counters->update_counters();
1890       counters->update_old_capacity(old_gen->capacity_in_bytes());
1891       counters->update_young_capacity(young_gen->capacity_in_bytes());
1892     }
1893 
1894     heap->resize_all_tlabs();
1895 
1896     // Resize the metaspace capacity after a collection
1897     MetaspaceGC::compute_new_size();
1898 
1899     if (log_is_enabled(Debug, gc, heap, exit)) {
1900       accumulated_time()->stop();
1901     }
1902 
1903     heap->print_heap_change(pre_gc_values);
1904 
1905     // Track memory usage and detect low memory
1906     MemoryService::track_memory_usage();
1907     heap->update_counters();
1908 
1909     heap->post_full_gc_dump(&_gc_timer);
1910   }
1911 
1912   if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
1913     Universe::verify("After GC");
1914   }
1915 
1916   // Re-verify object start arrays
1917   if (VerifyObjectStartArray &&
1918       VerifyAfterGC) {
1919     old_gen->verify_object_start_array();
1920   }
1921 
1922   if (ZapUnusedHeapArea) {
1923     old_gen->object_space()->check_mangled_unused_area_complete();
1924   }
1925 
1926   NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
1927 
1928   collection_exit.update();
1929 
1930   heap->print_heap_after_gc();
1931   heap->trace_heap_after_gc(&_gc_tracer);
1932 
1933   log_debug(gc, task, time)("VM-Thread " JLONG_FORMAT " " JLONG_FORMAT " " JLONG_FORMAT,
1934                          marking_start.ticks(), compaction_start.ticks(),
1935                          collection_exit.ticks());
1936 
1937   AdaptiveSizePolicyOutput::print(size_policy, heap->total_collections());
1938 
1939   _gc_timer.register_gc_end();
1940 
1941   _gc_tracer.report_dense_prefix(dense_prefix(old_space_id));
1942   _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions());
1943 
1944   return true;
1945 }
1946 
1947 class PCAddThreadRootsMarkingTaskClosure : public ThreadClosure {
1948 private:
1949   uint _worker_id;
1950 
1951 public:
1952   PCAddThreadRootsMarkingTaskClosure(uint worker_id) : _worker_id(worker_id) { }
1953   void do_thread(Thread* thread) {
1954     assert(ParallelScavengeHeap::heap()->is_gc_active(), "called outside gc");
1955 
1956     ResourceMark rm;
1957 
1958     ParCompactionManager* cm = ParCompactionManager::gc_thread_compaction_manager(_worker_id);
1959 
1960     PCMarkAndPushClosure mark_and_push_closure(cm);
1961     MarkingCodeBlobClosure mark_and_push_in_blobs(&mark_and_push_closure, !CodeBlobToOopClosure::FixRelocations);
1962 
1963     thread->oops_do(&mark_and_push_closure, &mark_and_push_in_blobs);
1964 
1965     // Do the real work
1966     cm->follow_marking_stacks();
1967   }
1968 };
1969 
1970 static void mark_from_roots_work(ParallelRootType::Value root_type, uint worker_id) {
1971   assert(ParallelScavengeHeap::heap()->is_gc_active(), "called outside gc");
1972 
1973   ParCompactionManager* cm =
1974     ParCompactionManager::gc_thread_compaction_manager(worker_id);
1975   PCMarkAndPushClosure mark_and_push_closure(cm);
1976 
1977   switch (root_type) {
1978     case ParallelRootType::class_loader_data:
1979       {
1980         CLDToOopClosure cld_closure(&mark_and_push_closure, ClassLoaderData::_claim_strong);
1981         ClassLoaderDataGraph::always_strong_cld_do(&cld_closure);
1982       }
1983       break;
1984 
1985     case ParallelRootType::code_cache:
1986       // Do not treat nmethods as strong roots for mark/sweep, since we can unload them.
1987       //ScavengableNMethods::scavengable_nmethods_do(CodeBlobToOopClosure(&mark_and_push_closure));
1988       break;
1989 
1990     case ParallelRootType::sentinel:
1991     DEBUG_ONLY(default:) // DEBUG_ONLY hack will create compile error on release builds (-Wswitch) and runtime check on debug builds
1992       fatal("Bad enumeration value: %u", root_type);
1993       break;
1994   }
1995 
1996   // Do the real work
1997   cm->follow_marking_stacks();
1998 }
1999 
2000 void steal_marking_work(TaskTerminator& terminator, uint worker_id) {
2001   assert(ParallelScavengeHeap::heap()->is_gc_active(), "called outside gc");
2002 
2003   ParCompactionManager* cm =
2004     ParCompactionManager::gc_thread_compaction_manager(worker_id);
2005 
2006   oop obj = NULL;
2007   ObjArrayTask task;
2008   do {
2009     while (ParCompactionManager::steal_objarray(worker_id,  task)) {
2010       cm->follow_array((objArrayOop)task.obj(), task.index());
2011       cm->follow_marking_stacks();
2012     }
2013     while (ParCompactionManager::steal(worker_id, obj)) {
2014       cm->follow_contents(obj);
2015       cm->follow_marking_stacks();
2016     }
2017   } while (!terminator.offer_termination());
2018 }
2019 
2020 class MarkFromRootsTask : public AbstractGangTask {
2021   StrongRootsScope _strong_roots_scope; // needed for Threads::possibly_parallel_threads_do
2022   OopStorageSetStrongParState<false /* concurrent */, false /* is_const */> _oop_storage_set_par_state;
2023   SequentialSubTasksDone _subtasks;
2024   TaskTerminator _terminator;
2025   uint _active_workers;
2026 
2027 public:
2028   MarkFromRootsTask(uint active_workers) :
2029       AbstractGangTask("MarkFromRootsTask"),
2030       _strong_roots_scope(active_workers),
2031       _subtasks(ParallelRootType::sentinel),
2032       _terminator(active_workers, ParCompactionManager::oop_task_queues()),
2033       _active_workers(active_workers) {
2034   }
2035 
2036   virtual void work(uint worker_id) {
2037     for (uint task = 0; _subtasks.try_claim_task(task); /*empty*/ ) {
2038       mark_from_roots_work(static_cast<ParallelRootType::Value>(task), worker_id);
2039     }
2040 
2041     PCAddThreadRootsMarkingTaskClosure closure(worker_id);
2042     Threads::possibly_parallel_threads_do(true /*parallel */, &closure);
2043 
2044     // Mark from OopStorages
2045     {
2046       ParCompactionManager* cm = ParCompactionManager::gc_thread_compaction_manager(worker_id);
2047       PCMarkAndPushClosure closure(cm);
2048       _oop_storage_set_par_state.oops_do(&closure);
2049       // Do the real work
2050       cm->follow_marking_stacks();
2051     }
2052 
2053     if (_active_workers > 1) {
2054       steal_marking_work(_terminator, worker_id);
2055     }
2056   }
2057 };
2058 
2059 class ParallelCompactRefProcProxyTask : public RefProcProxyTask {
2060   TaskTerminator _terminator;
2061 
2062 public:
2063   ParallelCompactRefProcProxyTask(uint max_workers)
2064     : RefProcProxyTask("ParallelCompactRefProcProxyTask", max_workers),
2065       _terminator(_max_workers, ParCompactionManager::oop_task_queues()) {}
2066 
2067   void work(uint worker_id) override {
2068     assert(worker_id < _max_workers, "sanity");
2069     ParCompactionManager* cm = (_tm == RefProcThreadModel::Single) ? ParCompactionManager::get_vmthread_cm() : ParCompactionManager::gc_thread_compaction_manager(worker_id);
2070     PCMarkAndPushClosure keep_alive(cm);
2071     BarrierEnqueueDiscoveredFieldClosure enqueue;
2072     ParCompactionManager::FollowStackClosure complete_gc(cm, (_tm == RefProcThreadModel::Single) ? nullptr : &_terminator, worker_id);
2073     _rp_task->rp_work(worker_id, PSParallelCompact::is_alive_closure(), &keep_alive, &enqueue, &complete_gc);
2074   }
2075 
2076   void prepare_run_task_hook() override {
2077     _terminator.reset_for_reuse(_queue_count);
2078   }
2079 };
2080 
2081 void PSParallelCompact::marking_phase(ParCompactionManager* cm,
2082                                       ParallelOldTracer *gc_tracer) {
2083   // Recursively traverse all live objects and mark them
2084   GCTraceTime(Info, gc, phases) tm("Marking Phase", &_gc_timer);
2085 
2086   uint active_gc_threads = ParallelScavengeHeap::heap()->workers().active_workers();
2087 
2088   // Need new claim bits before marking starts.
2089   ClassLoaderDataGraph::clear_claimed_marks();
2090 
2091   {
2092     GCTraceTime(Debug, gc, phases) tm("Par Mark", &_gc_timer);
2093 
2094     MarkFromRootsTask task(active_gc_threads);
2095     ParallelScavengeHeap::heap()->workers().run_task(&task);
2096   }
2097 
2098   // Process reference objects found during marking
2099   {
2100     GCTraceTime(Debug, gc, phases) tm("Reference Processing", &_gc_timer);
2101 
2102     ReferenceProcessorStats stats;
2103     ReferenceProcessorPhaseTimes pt(&_gc_timer, ref_processor()->max_num_queues());
2104 
2105     ref_processor()->set_active_mt_degree(active_gc_threads);
2106     ParallelCompactRefProcProxyTask task(ref_processor()->max_num_queues());
2107     stats = ref_processor()->process_discovered_references(task, pt);
2108 
2109     gc_tracer->report_gc_reference_stats(stats);
2110     pt.print_all_references();
2111   }
2112 
2113   // This is the point where the entire marking should have completed.
2114   ParCompactionManager::verify_all_marking_stack_empty();
2115 
2116   {
2117     GCTraceTime(Debug, gc, phases) tm("Weak Processing", &_gc_timer);
2118     WeakProcessor::weak_oops_do(&ParallelScavengeHeap::heap()->workers(),
2119                                 is_alive_closure(),
2120                                 &do_nothing_cl,
2121                                 1);
2122   }
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(&_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(purged_class);
2135 
2136     // Clean JVMCI metadata handles.
2137     JVMCI_ONLY(JVMCI::do_unloading(purged_class));
2138   }
2139 
2140   _gc_tracer.report_object_count_after_gc(is_alive_closure());
2141 }
2142 
2143 #ifdef ASSERT
2144 void PCAdjustPointerClosure::verify_cm(ParCompactionManager* cm) {
2145   assert(cm != NULL, "associate ParCompactionManage should not be NULL");
2146   auto vmthread_cm = ParCompactionManager::get_vmthread_cm();
2147   if (Thread::current()->is_VM_thread()) {
2148     assert(cm == vmthread_cm, "VM threads should use ParCompactionManager from get_vmthread_cm()");
2149   } else {
2150     assert(Thread::current()->is_Worker_thread(), "Must be a GC thread");
2151     assert(cm != vmthread_cm, "GC threads should use ParCompactionManager from gc_thread_compaction_manager()");
2152   }
2153 }
2154 #endif
2155 
2156 class PSAdjustTask final : public AbstractGangTask {
2157   SubTasksDone                               _sub_tasks;
2158   WeakProcessor::Task                        _weak_proc_task;
2159   OopStorageSetStrongParState<false, false>  _oop_storage_iter;
2160   uint                                       _nworkers;
2161 
2162   enum PSAdjustSubTask {
2163     PSAdjustSubTask_code_cache,
2164     PSAdjustSubTask_old_ref_process,
2165     PSAdjustSubTask_young_ref_process,
2166 
2167     PSAdjustSubTask_num_elements
2168   };
2169 
2170 public:
2171   PSAdjustTask(uint nworkers) :
2172     AbstractGangTask("PSAdjust task"),
2173     _sub_tasks(PSAdjustSubTask_num_elements),
2174     _weak_proc_task(nworkers),
2175     _nworkers(nworkers) {
2176     // Need new claim bits when tracing through and adjusting pointers.
2177     ClassLoaderDataGraph::clear_claimed_marks();
2178     if (nworkers > 1) {
2179       Threads::change_thread_claim_token();
2180     }
2181   }
2182 
2183   ~PSAdjustTask() {
2184     Threads::assert_all_threads_claimed();
2185   }
2186 
2187   void work(uint worker_id) {
2188     ParCompactionManager* cm = ParCompactionManager::gc_thread_compaction_manager(worker_id);
2189     PCAdjustPointerClosure adjust(cm);
2190     {
2191       ResourceMark rm;
2192       Threads::possibly_parallel_oops_do(_nworkers > 1, &adjust, nullptr);
2193     }
2194     _oop_storage_iter.oops_do(&adjust);
2195     {
2196       CLDToOopClosure cld_closure(&adjust, ClassLoaderData::_claim_strong);
2197       ClassLoaderDataGraph::cld_do(&cld_closure);
2198     }
2199     {
2200       AlwaysTrueClosure always_alive;
2201       _weak_proc_task.work(worker_id, &always_alive, &adjust);
2202     }
2203     if (_sub_tasks.try_claim_task(PSAdjustSubTask_code_cache)) {
2204       CodeBlobToOopClosure adjust_code(&adjust, CodeBlobToOopClosure::FixRelocations);
2205       CodeCache::blobs_do(&adjust_code);
2206     }
2207     if (_sub_tasks.try_claim_task(PSAdjustSubTask_old_ref_process)) {
2208       PSParallelCompact::ref_processor()->weak_oops_do(&adjust);
2209     }
2210     if (_sub_tasks.try_claim_task(PSAdjustSubTask_young_ref_process)) {
2211       // Roots were visited so references into the young gen in roots
2212       // may have been scanned.  Process them also.
2213       // Should the reference processor have a span that excludes
2214       // young gen objects?
2215       PSScavenge::reference_processor()->weak_oops_do(&adjust);
2216     }
2217     _sub_tasks.all_tasks_claimed();
2218   }
2219 };
2220 
2221 void PSParallelCompact::adjust_roots() {
2222   // Adjust the pointers to reflect the new locations
2223   GCTraceTime(Info, gc, phases) tm("Adjust Roots", &_gc_timer);
2224   uint nworkers = ParallelScavengeHeap::heap()->workers().active_workers();
2225   PSAdjustTask task(nworkers);
2226   ParallelScavengeHeap::heap()->workers().run_task(&task);
2227 }
2228 
2229 // Helper class to print 8 region numbers per line and then print the total at the end.
2230 class FillableRegionLogger : public StackObj {
2231 private:
2232   Log(gc, compaction) log;
2233   static const int LineLength = 8;
2234   size_t _regions[LineLength];
2235   int _next_index;
2236   bool _enabled;
2237   size_t _total_regions;
2238 public:
2239   FillableRegionLogger() : _next_index(0), _enabled(log_develop_is_enabled(Trace, gc, compaction)), _total_regions(0) { }
2240   ~FillableRegionLogger() {
2241     log.trace(SIZE_FORMAT " initially fillable regions", _total_regions);
2242   }
2243 
2244   void print_line() {
2245     if (!_enabled || _next_index == 0) {
2246       return;
2247     }
2248     FormatBuffer<> line("Fillable: ");
2249     for (int i = 0; i < _next_index; i++) {
2250       line.append(" " SIZE_FORMAT_W(7), _regions[i]);
2251     }
2252     log.trace("%s", line.buffer());
2253     _next_index = 0;
2254   }
2255 
2256   void handle(size_t region) {
2257     if (!_enabled) {
2258       return;
2259     }
2260     _regions[_next_index++] = region;
2261     if (_next_index == LineLength) {
2262       print_line();
2263     }
2264     _total_regions++;
2265   }
2266 };
2267 
2268 void PSParallelCompact::prepare_region_draining_tasks(uint parallel_gc_threads)
2269 {
2270   GCTraceTime(Trace, gc, phases) tm("Drain Task Setup", &_gc_timer);
2271 
2272   // Find the threads that are active
2273   uint worker_id = 0;
2274 
2275   // Find all regions that are available (can be filled immediately) and
2276   // distribute them to the thread stacks.  The iteration is done in reverse
2277   // order (high to low) so the regions will be removed in ascending order.
2278 
2279   const ParallelCompactData& sd = PSParallelCompact::summary_data();
2280 
2281   // id + 1 is used to test termination so unsigned  can
2282   // be used with an old_space_id == 0.
2283   FillableRegionLogger region_logger;
2284   for (unsigned int id = to_space_id; id + 1 > old_space_id; --id) {
2285     SpaceInfo* const space_info = _space_info + id;
2286     HeapWord* const new_top = space_info->new_top();
2287 
2288     const size_t beg_region = sd.addr_to_region_idx(space_info->dense_prefix());
2289     const size_t end_region =
2290       sd.addr_to_region_idx(sd.region_align_up(new_top));
2291 
2292     for (size_t cur = end_region - 1; cur + 1 > beg_region; --cur) {
2293       if (sd.region(cur)->claim_unsafe()) {
2294         ParCompactionManager* cm = ParCompactionManager::gc_thread_compaction_manager(worker_id);
2295         bool result = sd.region(cur)->mark_normal();
2296         assert(result, "Must succeed at this point.");
2297         cm->region_stack()->push(cur);
2298         region_logger.handle(cur);
2299         // Assign regions to tasks in round-robin fashion.
2300         if (++worker_id == parallel_gc_threads) {
2301           worker_id = 0;
2302         }
2303       }
2304     }
2305     region_logger.print_line();
2306   }
2307 }
2308 
2309 class TaskQueue : StackObj {
2310   volatile uint _counter;
2311   uint _size;
2312   uint _insert_index;
2313   PSParallelCompact::UpdateDensePrefixTask* _backing_array;
2314 public:
2315   explicit TaskQueue(uint size) : _counter(0), _size(size), _insert_index(0), _backing_array(NULL) {
2316     _backing_array = NEW_C_HEAP_ARRAY(PSParallelCompact::UpdateDensePrefixTask, _size, mtGC);
2317   }
2318   ~TaskQueue() {
2319     assert(_counter >= _insert_index, "not all queue elements were claimed");
2320     FREE_C_HEAP_ARRAY(T, _backing_array);
2321   }
2322 
2323   void push(const PSParallelCompact::UpdateDensePrefixTask& value) {
2324     assert(_insert_index < _size, "too small backing array");
2325     _backing_array[_insert_index++] = value;
2326   }
2327 
2328   bool try_claim(PSParallelCompact::UpdateDensePrefixTask& reference) {
2329     uint claimed = Atomic::fetch_and_add(&_counter, 1u);
2330     if (claimed < _insert_index) {
2331       reference = _backing_array[claimed];
2332       return true;
2333     } else {
2334       return false;
2335     }
2336   }
2337 };
2338 
2339 #define PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING 4
2340 
2341 void PSParallelCompact::enqueue_dense_prefix_tasks(TaskQueue& task_queue,
2342                                                    uint parallel_gc_threads) {
2343   GCTraceTime(Trace, gc, phases) tm("Dense Prefix Task Setup", &_gc_timer);
2344 
2345   ParallelCompactData& sd = PSParallelCompact::summary_data();
2346 
2347   // Iterate over all the spaces adding tasks for updating
2348   // regions in the dense prefix.  Assume that 1 gc thread
2349   // will work on opening the gaps and the remaining gc threads
2350   // will work on the dense prefix.
2351   unsigned int space_id;
2352   for (space_id = old_space_id; space_id < last_space_id; ++ space_id) {
2353     HeapWord* const dense_prefix_end = _space_info[space_id].dense_prefix();
2354     const MutableSpace* const space = _space_info[space_id].space();
2355 
2356     if (dense_prefix_end == space->bottom()) {
2357       // There is no dense prefix for this space.
2358       continue;
2359     }
2360 
2361     // The dense prefix is before this region.
2362     size_t region_index_end_dense_prefix =
2363         sd.addr_to_region_idx(dense_prefix_end);
2364     RegionData* const dense_prefix_cp =
2365       sd.region(region_index_end_dense_prefix);
2366     assert(dense_prefix_end == space->end() ||
2367            dense_prefix_cp->available() ||
2368            dense_prefix_cp->claimed(),
2369            "The region after the dense prefix should always be ready to fill");
2370 
2371     size_t region_index_start = sd.addr_to_region_idx(space->bottom());
2372 
2373     // Is there dense prefix work?
2374     size_t total_dense_prefix_regions =
2375       region_index_end_dense_prefix - region_index_start;
2376     // How many regions of the dense prefix should be given to
2377     // each thread?
2378     if (total_dense_prefix_regions > 0) {
2379       uint tasks_for_dense_prefix = 1;
2380       if (total_dense_prefix_regions <=
2381           (parallel_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING)) {
2382         // Don't over partition.  This assumes that
2383         // PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING is a small integer value
2384         // so there are not many regions to process.
2385         tasks_for_dense_prefix = parallel_gc_threads;
2386       } else {
2387         // Over partition
2388         tasks_for_dense_prefix = parallel_gc_threads *
2389           PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING;
2390       }
2391       size_t regions_per_thread = total_dense_prefix_regions /
2392         tasks_for_dense_prefix;
2393       // Give each thread at least 1 region.
2394       if (regions_per_thread == 0) {
2395         regions_per_thread = 1;
2396       }
2397 
2398       for (uint k = 0; k < tasks_for_dense_prefix; k++) {
2399         if (region_index_start >= region_index_end_dense_prefix) {
2400           break;
2401         }
2402         // region_index_end is not processed
2403         size_t region_index_end = MIN2(region_index_start + regions_per_thread,
2404                                        region_index_end_dense_prefix);
2405         task_queue.push(UpdateDensePrefixTask(SpaceId(space_id),
2406                                               region_index_start,
2407                                               region_index_end));
2408         region_index_start = region_index_end;
2409       }
2410     }
2411     // This gets any part of the dense prefix that did not
2412     // fit evenly.
2413     if (region_index_start < region_index_end_dense_prefix) {
2414       task_queue.push(UpdateDensePrefixTask(SpaceId(space_id),
2415                                             region_index_start,
2416                                             region_index_end_dense_prefix));
2417     }
2418   }
2419 }
2420 
2421 #ifdef ASSERT
2422 // Write a histogram of the number of times the block table was filled for a
2423 // region.
2424 void PSParallelCompact::write_block_fill_histogram()
2425 {
2426   if (!log_develop_is_enabled(Trace, gc, compaction)) {
2427     return;
2428   }
2429 
2430   Log(gc, compaction) log;
2431   ResourceMark rm;
2432   LogStream ls(log.trace());
2433   outputStream* out = &ls;
2434 
2435   typedef ParallelCompactData::RegionData rd_t;
2436   ParallelCompactData& sd = summary_data();
2437 
2438   for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2439     MutableSpace* const spc = _space_info[id].space();
2440     if (spc->bottom() != spc->top()) {
2441       const rd_t* const beg = sd.addr_to_region_ptr(spc->bottom());
2442       HeapWord* const top_aligned_up = sd.region_align_up(spc->top());
2443       const rd_t* const end = sd.addr_to_region_ptr(top_aligned_up);
2444 
2445       size_t histo[5] = { 0, 0, 0, 0, 0 };
2446       const size_t histo_len = sizeof(histo) / sizeof(size_t);
2447       const size_t region_cnt = pointer_delta(end, beg, sizeof(rd_t));
2448 
2449       for (const rd_t* cur = beg; cur < end; ++cur) {
2450         ++histo[MIN2(cur->blocks_filled_count(), histo_len - 1)];
2451       }
2452       out->print("Block fill histogram: %u %-4s" SIZE_FORMAT_W(5), id, space_names[id], region_cnt);
2453       for (size_t i = 0; i < histo_len; ++i) {
2454         out->print(" " SIZE_FORMAT_W(5) " %5.1f%%",
2455                    histo[i], 100.0 * histo[i] / region_cnt);
2456       }
2457       out->cr();
2458     }
2459   }
2460 }
2461 #endif // #ifdef ASSERT
2462 
2463 static void compaction_with_stealing_work(TaskTerminator* terminator, uint worker_id) {
2464   assert(ParallelScavengeHeap::heap()->is_gc_active(), "called outside gc");
2465 
2466   ParCompactionManager* cm =
2467     ParCompactionManager::gc_thread_compaction_manager(worker_id);
2468 
2469   // Drain the stacks that have been preloaded with regions
2470   // that are ready to fill.
2471 
2472   cm->drain_region_stacks();
2473 
2474   guarantee(cm->region_stack()->is_empty(), "Not empty");
2475 
2476   size_t region_index = 0;
2477 
2478   while (true) {
2479     if (ParCompactionManager::steal(worker_id, region_index)) {
2480       PSParallelCompact::fill_and_update_region(cm, region_index);
2481       cm->drain_region_stacks();
2482     } else if (PSParallelCompact::steal_unavailable_region(cm, region_index)) {
2483       // Fill and update an unavailable region with the help of a shadow region
2484       PSParallelCompact::fill_and_update_shadow_region(cm, region_index);
2485       cm->drain_region_stacks();
2486     } else {
2487       if (terminator->offer_termination()) {
2488         break;
2489       }
2490       // Go around again.
2491     }
2492   }
2493 }
2494 
2495 class UpdateDensePrefixAndCompactionTask: public AbstractGangTask {
2496   TaskQueue& _tq;
2497   TaskTerminator _terminator;
2498   uint _active_workers;
2499 
2500 public:
2501   UpdateDensePrefixAndCompactionTask(TaskQueue& tq, uint active_workers) :
2502       AbstractGangTask("UpdateDensePrefixAndCompactionTask"),
2503       _tq(tq),
2504       _terminator(active_workers, ParCompactionManager::region_task_queues()),
2505       _active_workers(active_workers) {
2506   }
2507   virtual void work(uint worker_id) {
2508     ParCompactionManager* cm = ParCompactionManager::gc_thread_compaction_manager(worker_id);
2509 
2510     for (PSParallelCompact::UpdateDensePrefixTask task; _tq.try_claim(task); /* empty */) {
2511       PSParallelCompact::update_and_deadwood_in_dense_prefix(cm,
2512                                                              task._space_id,
2513                                                              task._region_index_start,
2514                                                              task._region_index_end);
2515     }
2516 
2517     // Once a thread has drained it's stack, it should try to steal regions from
2518     // other threads.
2519     compaction_with_stealing_work(&_terminator, worker_id);
2520   }
2521 };
2522 
2523 void PSParallelCompact::compact() {
2524   GCTraceTime(Info, gc, phases) tm("Compaction Phase", &_gc_timer);
2525 
2526   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
2527   PSOldGen* old_gen = heap->old_gen();
2528   old_gen->start_array()->reset();
2529   uint active_gc_threads = ParallelScavengeHeap::heap()->workers().active_workers();
2530 
2531   // for [0..last_space_id)
2532   //     for [0..active_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING)
2533   //         push
2534   //     push
2535   //
2536   // max push count is thus: last_space_id * (active_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING + 1)
2537   TaskQueue task_queue(last_space_id * (active_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING + 1));
2538   initialize_shadow_regions(active_gc_threads);
2539   prepare_region_draining_tasks(active_gc_threads);
2540   enqueue_dense_prefix_tasks(task_queue, active_gc_threads);
2541 
2542   {
2543     GCTraceTime(Trace, gc, phases) tm("Par Compact", &_gc_timer);
2544 
2545     UpdateDensePrefixAndCompactionTask task(task_queue, active_gc_threads);
2546     ParallelScavengeHeap::heap()->workers().run_task(&task);
2547 
2548 #ifdef  ASSERT
2549     // Verify that all regions have been processed before the deferred updates.
2550     for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2551       verify_complete(SpaceId(id));
2552     }
2553 #endif
2554   }
2555 
2556   {
2557     GCTraceTime(Trace, gc, phases) tm("Deferred Updates", &_gc_timer);
2558     // Update the deferred objects, if any. In principle, any compaction
2559     // manager can be used. However, since the current thread is VM thread, we
2560     // use the rightful one to keep the verification logic happy.
2561     ParCompactionManager* cm = ParCompactionManager::get_vmthread_cm();
2562     for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2563       update_deferred_objects(cm, SpaceId(id));
2564     }
2565   }
2566 
2567   DEBUG_ONLY(write_block_fill_histogram());
2568 }
2569 
2570 #ifdef  ASSERT
2571 void PSParallelCompact::verify_complete(SpaceId space_id) {
2572   // All Regions between space bottom() to new_top() should be marked as filled
2573   // and all Regions between new_top() and top() should be available (i.e.,
2574   // should have been emptied).
2575   ParallelCompactData& sd = summary_data();
2576   SpaceInfo si = _space_info[space_id];
2577   HeapWord* new_top_addr = sd.region_align_up(si.new_top());
2578   HeapWord* old_top_addr = sd.region_align_up(si.space()->top());
2579   const size_t beg_region = sd.addr_to_region_idx(si.space()->bottom());
2580   const size_t new_top_region = sd.addr_to_region_idx(new_top_addr);
2581   const size_t old_top_region = sd.addr_to_region_idx(old_top_addr);
2582 
2583   bool issued_a_warning = false;
2584 
2585   size_t cur_region;
2586   for (cur_region = beg_region; cur_region < new_top_region; ++cur_region) {
2587     const RegionData* const c = sd.region(cur_region);
2588     if (!c->completed()) {
2589       log_warning(gc)("region " SIZE_FORMAT " not filled: destination_count=%u",
2590                       cur_region, c->destination_count());
2591       issued_a_warning = true;
2592     }
2593   }
2594 
2595   for (cur_region = new_top_region; cur_region < old_top_region; ++cur_region) {
2596     const RegionData* const c = sd.region(cur_region);
2597     if (!c->available()) {
2598       log_warning(gc)("region " SIZE_FORMAT " not empty: destination_count=%u",
2599                       cur_region, c->destination_count());
2600       issued_a_warning = true;
2601     }
2602   }
2603 
2604   if (issued_a_warning) {
2605     print_region_ranges();
2606   }
2607 }
2608 #endif  // #ifdef ASSERT
2609 
2610 inline void UpdateOnlyClosure::do_addr(HeapWord* addr) {
2611   _start_array->allocate_block(addr);
2612   compaction_manager()->update_contents(cast_to_oop(addr));
2613 }
2614 
2615 // Update interior oops in the ranges of regions [beg_region, end_region).
2616 void
2617 PSParallelCompact::update_and_deadwood_in_dense_prefix(ParCompactionManager* cm,
2618                                                        SpaceId space_id,
2619                                                        size_t beg_region,
2620                                                        size_t end_region) {
2621   ParallelCompactData& sd = summary_data();
2622   ParMarkBitMap* const mbm = mark_bitmap();
2623 
2624   HeapWord* beg_addr = sd.region_to_addr(beg_region);
2625   HeapWord* const end_addr = sd.region_to_addr(end_region);
2626   assert(beg_region <= end_region, "bad region range");
2627   assert(end_addr <= dense_prefix(space_id), "not in the dense prefix");
2628 
2629 #ifdef  ASSERT
2630   // Claim the regions to avoid triggering an assert when they are marked as
2631   // filled.
2632   for (size_t claim_region = beg_region; claim_region < end_region; ++claim_region) {
2633     assert(sd.region(claim_region)->claim_unsafe(), "claim() failed");
2634   }
2635 #endif  // #ifdef ASSERT
2636 
2637   if (beg_addr != space(space_id)->bottom()) {
2638     // Find the first live object or block of dead space that *starts* in this
2639     // range of regions.  If a partial object crosses onto the region, skip it;
2640     // it will be marked for 'deferred update' when the object head is
2641     // processed.  If dead space crosses onto the region, it is also skipped; it
2642     // will be filled when the prior region is processed.  If neither of those
2643     // apply, the first word in the region is the start of a live object or dead
2644     // space.
2645     assert(beg_addr > space(space_id)->bottom(), "sanity");
2646     const RegionData* const cp = sd.region(beg_region);
2647     if (cp->partial_obj_size() != 0) {
2648       beg_addr = sd.partial_obj_end(beg_region);
2649     } else if (dead_space_crosses_boundary(cp, mbm->addr_to_bit(beg_addr))) {
2650       beg_addr = mbm->find_obj_beg(beg_addr, end_addr);
2651     }
2652   }
2653 
2654   if (beg_addr < end_addr) {
2655     // A live object or block of dead space starts in this range of Regions.
2656      HeapWord* const dense_prefix_end = dense_prefix(space_id);
2657 
2658     // Create closures and iterate.
2659     UpdateOnlyClosure update_closure(mbm, cm, space_id);
2660     FillClosure fill_closure(cm, space_id);
2661     ParMarkBitMap::IterationStatus status;
2662     status = mbm->iterate(&update_closure, &fill_closure, beg_addr, end_addr,
2663                           dense_prefix_end);
2664     if (status == ParMarkBitMap::incomplete) {
2665       update_closure.do_addr(update_closure.source());
2666     }
2667   }
2668 
2669   // Mark the regions as filled.
2670   RegionData* const beg_cp = sd.region(beg_region);
2671   RegionData* const end_cp = sd.region(end_region);
2672   for (RegionData* cp = beg_cp; cp < end_cp; ++cp) {
2673     cp->set_completed();
2674   }
2675 }
2676 
2677 // Return the SpaceId for the space containing addr.  If addr is not in the
2678 // heap, last_space_id is returned.  In debug mode it expects the address to be
2679 // in the heap and asserts such.
2680 PSParallelCompact::SpaceId PSParallelCompact::space_id(HeapWord* addr) {
2681   assert(ParallelScavengeHeap::heap()->is_in_reserved(addr), "addr not in the heap");
2682 
2683   for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2684     if (_space_info[id].space()->contains(addr)) {
2685       return SpaceId(id);
2686     }
2687   }
2688 
2689   assert(false, "no space contains the addr");
2690   return last_space_id;
2691 }
2692 
2693 void PSParallelCompact::update_deferred_objects(ParCompactionManager* cm,
2694                                                 SpaceId id) {
2695   assert(id < last_space_id, "bad space id");
2696 
2697   ParallelCompactData& sd = summary_data();
2698   const SpaceInfo* const space_info = _space_info + id;
2699   ObjectStartArray* const start_array = space_info->start_array();
2700 
2701   const MutableSpace* const space = space_info->space();
2702   assert(space_info->dense_prefix() >= space->bottom(), "dense_prefix not set");
2703   HeapWord* const beg_addr = space_info->dense_prefix();
2704   HeapWord* const end_addr = sd.region_align_up(space_info->new_top());
2705 
2706   const RegionData* const beg_region = sd.addr_to_region_ptr(beg_addr);
2707   const RegionData* const end_region = sd.addr_to_region_ptr(end_addr);
2708   const RegionData* cur_region;
2709   for (cur_region = beg_region; cur_region < end_region; ++cur_region) {
2710     HeapWord* const addr = cur_region->deferred_obj_addr();
2711     if (addr != NULL) {
2712       if (start_array != NULL) {
2713         start_array->allocate_block(addr);
2714       }
2715       cm->update_contents(cast_to_oop(addr));
2716       assert(oopDesc::is_oop_or_null(cast_to_oop(addr)), "Expected an oop or NULL at " PTR_FORMAT, p2i(cast_to_oop(addr)));
2717     }
2718   }
2719 }
2720 
2721 // Skip over count live words starting from beg, and return the address of the
2722 // next live word.  Unless marked, the word corresponding to beg is assumed to
2723 // be dead.  Callers must either ensure beg does not correspond to the middle of
2724 // an object, or account for those live words in some other way.  Callers must
2725 // also ensure that there are enough live words in the range [beg, end) to skip.
2726 HeapWord*
2727 PSParallelCompact::skip_live_words(HeapWord* beg, HeapWord* end, size_t count)
2728 {
2729   assert(count > 0, "sanity");
2730 
2731   ParMarkBitMap* m = mark_bitmap();
2732   idx_t bits_to_skip = m->words_to_bits(count);
2733   idx_t cur_beg = m->addr_to_bit(beg);
2734   const idx_t search_end = m->align_range_end(m->addr_to_bit(end));
2735 
2736   do {
2737     cur_beg = m->find_obj_beg(cur_beg, search_end);
2738     idx_t cur_end = m->find_obj_end(cur_beg, search_end);
2739     const size_t obj_bits = cur_end - cur_beg + 1;
2740     if (obj_bits > bits_to_skip) {
2741       return m->bit_to_addr(cur_beg + bits_to_skip);
2742     }
2743     bits_to_skip -= obj_bits;
2744     cur_beg = cur_end + 1;
2745   } while (bits_to_skip > 0);
2746 
2747   // Skipping the desired number of words landed just past the end of an object.
2748   // Find the start of the next object.
2749   cur_beg = m->find_obj_beg(cur_beg, search_end);
2750   assert(cur_beg < m->addr_to_bit(end), "not enough live words to skip");
2751   return m->bit_to_addr(cur_beg);
2752 }
2753 
2754 HeapWord* PSParallelCompact::first_src_addr(HeapWord* const dest_addr,
2755                                             SpaceId src_space_id,
2756                                             size_t src_region_idx)
2757 {
2758   assert(summary_data().is_region_aligned(dest_addr), "not aligned");
2759 
2760   const SplitInfo& split_info = _space_info[src_space_id].split_info();
2761   if (split_info.dest_region_addr() == dest_addr) {
2762     // The partial object ending at the split point contains the first word to
2763     // be copied to dest_addr.
2764     return split_info.first_src_addr();
2765   }
2766 
2767   const ParallelCompactData& sd = summary_data();
2768   ParMarkBitMap* const bitmap = mark_bitmap();
2769   const size_t RegionSize = ParallelCompactData::RegionSize;
2770 
2771   assert(sd.is_region_aligned(dest_addr), "not aligned");
2772   const RegionData* const src_region_ptr = sd.region(src_region_idx);
2773   const size_t partial_obj_size = src_region_ptr->partial_obj_size();
2774   HeapWord* const src_region_destination = src_region_ptr->destination();
2775 
2776   assert(dest_addr >= src_region_destination, "wrong src region");
2777   assert(src_region_ptr->data_size() > 0, "src region cannot be empty");
2778 
2779   HeapWord* const src_region_beg = sd.region_to_addr(src_region_idx);
2780   HeapWord* const src_region_end = src_region_beg + RegionSize;
2781 
2782   HeapWord* addr = src_region_beg;
2783   if (dest_addr == src_region_destination) {
2784     // Return the first live word in the source region.
2785     if (partial_obj_size == 0) {
2786       addr = bitmap->find_obj_beg(addr, src_region_end);
2787       assert(addr < src_region_end, "no objects start in src region");
2788     }
2789     return addr;
2790   }
2791 
2792   // Must skip some live data.
2793   size_t words_to_skip = dest_addr - src_region_destination;
2794   assert(src_region_ptr->data_size() > words_to_skip, "wrong src region");
2795 
2796   if (partial_obj_size >= words_to_skip) {
2797     // All the live words to skip are part of the partial object.
2798     addr += words_to_skip;
2799     if (partial_obj_size == words_to_skip) {
2800       // Find the first live word past the partial object.
2801       addr = bitmap->find_obj_beg(addr, src_region_end);
2802       assert(addr < src_region_end, "wrong src region");
2803     }
2804     return addr;
2805   }
2806 
2807   // Skip over the partial object (if any).
2808   if (partial_obj_size != 0) {
2809     words_to_skip -= partial_obj_size;
2810     addr += partial_obj_size;
2811   }
2812 
2813   // Skip over live words due to objects that start in the region.
2814   addr = skip_live_words(addr, src_region_end, words_to_skip);
2815   assert(addr < src_region_end, "wrong src region");
2816   return addr;
2817 }
2818 
2819 void PSParallelCompact::decrement_destination_counts(ParCompactionManager* cm,
2820                                                      SpaceId src_space_id,
2821                                                      size_t beg_region,
2822                                                      HeapWord* end_addr)
2823 {
2824   ParallelCompactData& sd = summary_data();
2825 
2826 #ifdef ASSERT
2827   MutableSpace* const src_space = _space_info[src_space_id].space();
2828   HeapWord* const beg_addr = sd.region_to_addr(beg_region);
2829   assert(src_space->contains(beg_addr) || beg_addr == src_space->end(),
2830          "src_space_id does not match beg_addr");
2831   assert(src_space->contains(end_addr) || end_addr == src_space->end(),
2832          "src_space_id does not match end_addr");
2833 #endif // #ifdef ASSERT
2834 
2835   RegionData* const beg = sd.region(beg_region);
2836   RegionData* const end = sd.addr_to_region_ptr(sd.region_align_up(end_addr));
2837 
2838   // Regions up to new_top() are enqueued if they become available.
2839   HeapWord* const new_top = _space_info[src_space_id].new_top();
2840   RegionData* const enqueue_end =
2841     sd.addr_to_region_ptr(sd.region_align_up(new_top));
2842 
2843   for (RegionData* cur = beg; cur < end; ++cur) {
2844     assert(cur->data_size() > 0, "region must have live data");
2845     cur->decrement_destination_count();
2846     if (cur < enqueue_end && cur->available() && cur->claim()) {
2847       if (cur->mark_normal()) {
2848         cm->push_region(sd.region(cur));
2849       } else if (cur->mark_copied()) {
2850         // Try to copy the content of the shadow region back to its corresponding
2851         // heap region if the shadow region is filled. Otherwise, the GC thread
2852         // fills the shadow region will copy the data back (see
2853         // MoveAndUpdateShadowClosure::complete_region).
2854         copy_back(sd.region_to_addr(cur->shadow_region()), sd.region_to_addr(cur));
2855         ParCompactionManager::push_shadow_region_mt_safe(cur->shadow_region());
2856         cur->set_completed();
2857       }
2858     }
2859   }
2860 }
2861 
2862 size_t PSParallelCompact::next_src_region(MoveAndUpdateClosure& closure,
2863                                           SpaceId& src_space_id,
2864                                           HeapWord*& src_space_top,
2865                                           HeapWord* end_addr)
2866 {
2867   typedef ParallelCompactData::RegionData RegionData;
2868 
2869   ParallelCompactData& sd = PSParallelCompact::summary_data();
2870   const size_t region_size = ParallelCompactData::RegionSize;
2871 
2872   size_t src_region_idx = 0;
2873 
2874   // Skip empty regions (if any) up to the top of the space.
2875   HeapWord* const src_aligned_up = sd.region_align_up(end_addr);
2876   RegionData* src_region_ptr = sd.addr_to_region_ptr(src_aligned_up);
2877   HeapWord* const top_aligned_up = sd.region_align_up(src_space_top);
2878   const RegionData* const top_region_ptr =
2879     sd.addr_to_region_ptr(top_aligned_up);
2880   while (src_region_ptr < top_region_ptr && src_region_ptr->data_size() == 0) {
2881     ++src_region_ptr;
2882   }
2883 
2884   if (src_region_ptr < top_region_ptr) {
2885     // The next source region is in the current space.  Update src_region_idx
2886     // and the source address to match src_region_ptr.
2887     src_region_idx = sd.region(src_region_ptr);
2888     HeapWord* const src_region_addr = sd.region_to_addr(src_region_idx);
2889     if (src_region_addr > closure.source()) {
2890       closure.set_source(src_region_addr);
2891     }
2892     return src_region_idx;
2893   }
2894 
2895   // Switch to a new source space and find the first non-empty region.
2896   unsigned int space_id = src_space_id + 1;
2897   assert(space_id < last_space_id, "not enough spaces");
2898 
2899   HeapWord* const destination = closure.destination();
2900 
2901   do {
2902     MutableSpace* space = _space_info[space_id].space();
2903     HeapWord* const bottom = space->bottom();
2904     const RegionData* const bottom_cp = sd.addr_to_region_ptr(bottom);
2905 
2906     // Iterate over the spaces that do not compact into themselves.
2907     if (bottom_cp->destination() != bottom) {
2908       HeapWord* const top_aligned_up = sd.region_align_up(space->top());
2909       const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
2910 
2911       for (const RegionData* src_cp = bottom_cp; src_cp < top_cp; ++src_cp) {
2912         if (src_cp->live_obj_size() > 0) {
2913           // Found it.
2914           assert(src_cp->destination() == destination,
2915                  "first live obj in the space must match the destination");
2916           assert(src_cp->partial_obj_size() == 0,
2917                  "a space cannot begin with a partial obj");
2918 
2919           src_space_id = SpaceId(space_id);
2920           src_space_top = space->top();
2921           const size_t src_region_idx = sd.region(src_cp);
2922           closure.set_source(sd.region_to_addr(src_region_idx));
2923           return src_region_idx;
2924         } else {
2925           assert(src_cp->data_size() == 0, "sanity");
2926         }
2927       }
2928     }
2929   } while (++space_id < last_space_id);
2930 
2931   assert(false, "no source region was found");
2932   return 0;
2933 }
2934 
2935 void PSParallelCompact::fill_region(ParCompactionManager* cm, MoveAndUpdateClosure& closure, size_t region_idx)
2936 {
2937   typedef ParMarkBitMap::IterationStatus IterationStatus;
2938   ParMarkBitMap* const bitmap = mark_bitmap();
2939   ParallelCompactData& sd = summary_data();
2940   RegionData* const region_ptr = sd.region(region_idx);
2941 
2942   // Get the source region and related info.
2943   size_t src_region_idx = region_ptr->source_region();
2944   SpaceId src_space_id = space_id(sd.region_to_addr(src_region_idx));
2945   HeapWord* src_space_top = _space_info[src_space_id].space()->top();
2946   HeapWord* dest_addr = sd.region_to_addr(region_idx);
2947 
2948   closure.set_source(first_src_addr(dest_addr, src_space_id, src_region_idx));
2949 
2950   // Adjust src_region_idx to prepare for decrementing destination counts (the
2951   // destination count is not decremented when a region is copied to itself).
2952   if (src_region_idx == region_idx) {
2953     src_region_idx += 1;
2954   }
2955 
2956   if (bitmap->is_unmarked(closure.source())) {
2957     // The first source word is in the middle of an object; copy the remainder
2958     // of the object or as much as will fit.  The fact that pointer updates were
2959     // deferred will be noted when the object header is processed.
2960     HeapWord* const old_src_addr = closure.source();
2961     closure.copy_partial_obj();
2962     if (closure.is_full()) {
2963       decrement_destination_counts(cm, src_space_id, src_region_idx,
2964                                    closure.source());
2965       region_ptr->set_deferred_obj_addr(NULL);
2966       closure.complete_region(cm, dest_addr, region_ptr);
2967       return;
2968     }
2969 
2970     HeapWord* const end_addr = sd.region_align_down(closure.source());
2971     if (sd.region_align_down(old_src_addr) != end_addr) {
2972       // The partial object was copied from more than one source region.
2973       decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
2974 
2975       // Move to the next source region, possibly switching spaces as well.  All
2976       // args except end_addr may be modified.
2977       src_region_idx = next_src_region(closure, src_space_id, src_space_top,
2978                                        end_addr);
2979     }
2980   }
2981 
2982   do {
2983     HeapWord* const cur_addr = closure.source();
2984     HeapWord* const end_addr = MIN2(sd.region_align_up(cur_addr + 1),
2985                                     src_space_top);
2986     IterationStatus status = bitmap->iterate(&closure, cur_addr, end_addr);
2987 
2988     if (status == ParMarkBitMap::incomplete) {
2989       // The last obj that starts in the source region does not end in the
2990       // region.
2991       assert(closure.source() < end_addr, "sanity");
2992       HeapWord* const obj_beg = closure.source();
2993       HeapWord* const range_end = MIN2(obj_beg + closure.words_remaining(),
2994                                        src_space_top);
2995       HeapWord* const obj_end = bitmap->find_obj_end(obj_beg, range_end);
2996       if (obj_end < range_end) {
2997         // The end was found; the entire object will fit.
2998         status = closure.do_addr(obj_beg, bitmap->obj_size(obj_beg, obj_end));
2999         assert(status != ParMarkBitMap::would_overflow, "sanity");
3000       } else {
3001         // The end was not found; the object will not fit.
3002         assert(range_end < src_space_top, "obj cannot cross space boundary");
3003         status = ParMarkBitMap::would_overflow;
3004       }
3005     }
3006 
3007     if (status == ParMarkBitMap::would_overflow) {
3008       // The last object did not fit.  Note that interior oop updates were
3009       // deferred, then copy enough of the object to fill the region.
3010       region_ptr->set_deferred_obj_addr(closure.destination());
3011       status = closure.copy_until_full(); // copies from closure.source()
3012 
3013       decrement_destination_counts(cm, src_space_id, src_region_idx,
3014                                    closure.source());
3015       closure.complete_region(cm, dest_addr, region_ptr);
3016       return;
3017     }
3018 
3019     if (status == ParMarkBitMap::full) {
3020       decrement_destination_counts(cm, src_space_id, src_region_idx,
3021                                    closure.source());
3022       region_ptr->set_deferred_obj_addr(NULL);
3023       closure.complete_region(cm, dest_addr, region_ptr);
3024       return;
3025     }
3026 
3027     decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
3028 
3029     // Move to the next source region, possibly switching spaces as well.  All
3030     // args except end_addr may be modified.
3031     src_region_idx = next_src_region(closure, src_space_id, src_space_top,
3032                                      end_addr);
3033   } while (true);
3034 }
3035 
3036 void PSParallelCompact::fill_and_update_region(ParCompactionManager* cm, size_t region_idx)
3037 {
3038   MoveAndUpdateClosure cl(mark_bitmap(), cm, region_idx);
3039   fill_region(cm, cl, region_idx);
3040 }
3041 
3042 void PSParallelCompact::fill_and_update_shadow_region(ParCompactionManager* cm, size_t region_idx)
3043 {
3044   // Get a shadow region first
3045   ParallelCompactData& sd = summary_data();
3046   RegionData* const region_ptr = sd.region(region_idx);
3047   size_t shadow_region = ParCompactionManager::pop_shadow_region_mt_safe(region_ptr);
3048   // The InvalidShadow return value indicates the corresponding heap region is available,
3049   // so use MoveAndUpdateClosure to fill the normal region. Otherwise, use
3050   // MoveAndUpdateShadowClosure to fill the acquired shadow region.
3051   if (shadow_region == ParCompactionManager::InvalidShadow) {
3052     MoveAndUpdateClosure cl(mark_bitmap(), cm, region_idx);
3053     region_ptr->shadow_to_normal();
3054     return fill_region(cm, cl, region_idx);
3055   } else {
3056     MoveAndUpdateShadowClosure cl(mark_bitmap(), cm, region_idx, shadow_region);
3057     return fill_region(cm, cl, region_idx);
3058   }
3059 }
3060 
3061 void PSParallelCompact::copy_back(HeapWord *shadow_addr, HeapWord *region_addr)
3062 {
3063   Copy::aligned_conjoint_words(shadow_addr, region_addr, _summary_data.RegionSize);
3064 }
3065 
3066 bool PSParallelCompact::steal_unavailable_region(ParCompactionManager* cm, size_t &region_idx)
3067 {
3068   size_t next = cm->next_shadow_region();
3069   ParallelCompactData& sd = summary_data();
3070   size_t old_new_top = sd.addr_to_region_idx(_space_info[old_space_id].new_top());
3071   uint active_gc_threads = ParallelScavengeHeap::heap()->workers().active_workers();
3072 
3073   while (next < old_new_top) {
3074     if (sd.region(next)->mark_shadow()) {
3075       region_idx = next;
3076       return true;
3077     }
3078     next = cm->move_next_shadow_region_by(active_gc_threads);
3079   }
3080 
3081   return false;
3082 }
3083 
3084 // The shadow region is an optimization to address region dependencies in full GC. The basic
3085 // idea is making more regions available by temporally storing their live objects in empty
3086 // shadow regions to resolve dependencies between them and the destination regions. Therefore,
3087 // GC threads need not wait destination regions to be available before processing sources.
3088 //
3089 // A typical workflow would be:
3090 // After draining its own stack and failing to steal from others, a GC worker would pick an
3091 // unavailable region (destination count > 0) and get a shadow region. Then the worker fills
3092 // the shadow region by copying live objects from source regions of the unavailable one. Once
3093 // the unavailable region becomes available, the data in the shadow region will be copied back.
3094 // Shadow regions are empty regions in the to-space and regions between top and end of other spaces.
3095 void PSParallelCompact::initialize_shadow_regions(uint parallel_gc_threads)
3096 {
3097   const ParallelCompactData& sd = PSParallelCompact::summary_data();
3098 
3099   for (unsigned int id = old_space_id; id < last_space_id; ++id) {
3100     SpaceInfo* const space_info = _space_info + id;
3101     MutableSpace* const space = space_info->space();
3102 
3103     const size_t beg_region =
3104       sd.addr_to_region_idx(sd.region_align_up(MAX2(space_info->new_top(), space->top())));
3105     const size_t end_region =
3106       sd.addr_to_region_idx(sd.region_align_down(space->end()));
3107 
3108     for (size_t cur = beg_region; cur < end_region; ++cur) {
3109       ParCompactionManager::push_shadow_region(cur);
3110     }
3111   }
3112 
3113   size_t beg_region = sd.addr_to_region_idx(_space_info[old_space_id].dense_prefix());
3114   for (uint i = 0; i < parallel_gc_threads; i++) {
3115     ParCompactionManager *cm = ParCompactionManager::gc_thread_compaction_manager(i);
3116     cm->set_next_shadow_region(beg_region + i);
3117   }
3118 }
3119 
3120 void PSParallelCompact::fill_blocks(size_t region_idx)
3121 {
3122   // Fill in the block table elements for the specified region.  Each block
3123   // table element holds the number of live words in the region that are to the
3124   // left of the first object that starts in the block.  Thus only blocks in
3125   // which an object starts need to be filled.
3126   //
3127   // The algorithm scans the section of the bitmap that corresponds to the
3128   // region, keeping a running total of the live words.  When an object start is
3129   // found, if it's the first to start in the block that contains it, the
3130   // current total is written to the block table element.
3131   const size_t Log2BlockSize = ParallelCompactData::Log2BlockSize;
3132   const size_t Log2RegionSize = ParallelCompactData::Log2RegionSize;
3133   const size_t RegionSize = ParallelCompactData::RegionSize;
3134 
3135   ParallelCompactData& sd = summary_data();
3136   const size_t partial_obj_size = sd.region(region_idx)->partial_obj_size();
3137   if (partial_obj_size >= RegionSize) {
3138     return; // No objects start in this region.
3139   }
3140 
3141   // Ensure the first loop iteration decides that the block has changed.
3142   size_t cur_block = sd.block_count();
3143 
3144   const ParMarkBitMap* const bitmap = mark_bitmap();
3145 
3146   const size_t Log2BitsPerBlock = Log2BlockSize - LogMinObjAlignment;
3147   assert((size_t)1 << Log2BitsPerBlock ==
3148          bitmap->words_to_bits(ParallelCompactData::BlockSize), "sanity");
3149 
3150   size_t beg_bit = bitmap->words_to_bits(region_idx << Log2RegionSize);
3151   const size_t range_end = beg_bit + bitmap->words_to_bits(RegionSize);
3152   size_t live_bits = bitmap->words_to_bits(partial_obj_size);
3153   beg_bit = bitmap->find_obj_beg(beg_bit + live_bits, range_end);
3154   while (beg_bit < range_end) {
3155     const size_t new_block = beg_bit >> Log2BitsPerBlock;
3156     if (new_block != cur_block) {
3157       cur_block = new_block;
3158       sd.block(cur_block)->set_offset(bitmap->bits_to_words(live_bits));
3159     }
3160 
3161     const size_t end_bit = bitmap->find_obj_end(beg_bit, range_end);
3162     if (end_bit < range_end - 1) {
3163       live_bits += end_bit - beg_bit + 1;
3164       beg_bit = bitmap->find_obj_beg(end_bit + 1, range_end);
3165     } else {
3166       return;
3167     }
3168   }
3169 }
3170 
3171 ParMarkBitMap::IterationStatus MoveAndUpdateClosure::copy_until_full()
3172 {
3173   if (source() != copy_destination()) {
3174     DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3175     Copy::aligned_conjoint_words(source(), copy_destination(), words_remaining());
3176   }
3177   update_state(words_remaining());
3178   assert(is_full(), "sanity");
3179   return ParMarkBitMap::full;
3180 }
3181 
3182 void MoveAndUpdateClosure::copy_partial_obj()
3183 {
3184   size_t words = words_remaining();
3185 
3186   HeapWord* const range_end = MIN2(source() + words, bitmap()->region_end());
3187   HeapWord* const end_addr = bitmap()->find_obj_end(source(), range_end);
3188   if (end_addr < range_end) {
3189     words = bitmap()->obj_size(source(), end_addr);
3190   }
3191 
3192   // This test is necessary; if omitted, the pointer updates to a partial object
3193   // that crosses the dense prefix boundary could be overwritten.
3194   if (source() != copy_destination()) {
3195     DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3196     Copy::aligned_conjoint_words(source(), copy_destination(), words);
3197   }
3198   update_state(words);
3199 }
3200 
3201 void MoveAndUpdateClosure::complete_region(ParCompactionManager *cm, HeapWord *dest_addr,
3202                                            PSParallelCompact::RegionData *region_ptr) {
3203   assert(region_ptr->shadow_state() == ParallelCompactData::RegionData::NormalRegion, "Region should be finished");
3204   region_ptr->set_completed();
3205 }
3206 
3207 ParMarkBitMapClosure::IterationStatus
3208 MoveAndUpdateClosure::do_addr(HeapWord* addr, size_t words) {
3209   assert(destination() != NULL, "sanity");
3210   assert(bitmap()->obj_size(addr) == words, "bad size");
3211 
3212   _source = addr;
3213   assert(PSParallelCompact::summary_data().calc_new_pointer(source(), compaction_manager()) ==
3214          destination(), "wrong destination");
3215 
3216   if (words > words_remaining()) {
3217     return ParMarkBitMap::would_overflow;
3218   }
3219 
3220   // The start_array must be updated even if the object is not moving.
3221   if (_start_array != NULL) {
3222     _start_array->allocate_block(destination());
3223   }
3224 
3225   if (copy_destination() != source()) {
3226     DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3227     Copy::aligned_conjoint_words(source(), copy_destination(), words);
3228   }
3229 
3230   oop moved_oop = cast_to_oop(copy_destination());
3231   compaction_manager()->update_contents(moved_oop);
3232   assert(oopDesc::is_oop_or_null(moved_oop), "Expected an oop or NULL at " PTR_FORMAT, p2i(moved_oop));
3233 
3234   update_state(words);
3235   assert(copy_destination() == cast_from_oop<HeapWord*>(moved_oop) + moved_oop->size(), "sanity");
3236   return is_full() ? ParMarkBitMap::full : ParMarkBitMap::incomplete;
3237 }
3238 
3239 void MoveAndUpdateShadowClosure::complete_region(ParCompactionManager *cm, HeapWord *dest_addr,
3240                                                  PSParallelCompact::RegionData *region_ptr) {
3241   assert(region_ptr->shadow_state() == ParallelCompactData::RegionData::ShadowRegion, "Region should be shadow");
3242   // Record the shadow region index
3243   region_ptr->set_shadow_region(_shadow);
3244   // Mark the shadow region as filled to indicate the data is ready to be
3245   // copied back
3246   region_ptr->mark_filled();
3247   // Try to copy the content of the shadow region back to its corresponding
3248   // heap region if available; the GC thread that decreases the destination
3249   // count to zero will do the copying otherwise (see
3250   // PSParallelCompact::decrement_destination_counts).
3251   if (((region_ptr->available() && region_ptr->claim()) || region_ptr->claimed()) && region_ptr->mark_copied()) {
3252     region_ptr->set_completed();
3253     PSParallelCompact::copy_back(PSParallelCompact::summary_data().region_to_addr(_shadow), dest_addr);
3254     ParCompactionManager::push_shadow_region_mt_safe(_shadow);
3255   }
3256 }
3257 
3258 UpdateOnlyClosure::UpdateOnlyClosure(ParMarkBitMap* mbm,
3259                                      ParCompactionManager* cm,
3260                                      PSParallelCompact::SpaceId space_id) :
3261   ParMarkBitMapClosure(mbm, cm),
3262   _space_id(space_id),
3263   _start_array(PSParallelCompact::start_array(space_id))
3264 {
3265 }
3266 
3267 // Updates the references in the object to their new values.
3268 ParMarkBitMapClosure::IterationStatus
3269 UpdateOnlyClosure::do_addr(HeapWord* addr, size_t words) {
3270   do_addr(addr);
3271   return ParMarkBitMap::incomplete;
3272 }
3273 
3274 FillClosure::FillClosure(ParCompactionManager* cm, PSParallelCompact::SpaceId space_id) :
3275   ParMarkBitMapClosure(PSParallelCompact::mark_bitmap(), cm),
3276   _start_array(PSParallelCompact::start_array(space_id))
3277 {
3278   assert(space_id == PSParallelCompact::old_space_id,
3279          "cannot use FillClosure in the young gen");
3280 }
3281 
3282 ParMarkBitMapClosure::IterationStatus
3283 FillClosure::do_addr(HeapWord* addr, size_t size) {
3284   CollectedHeap::fill_with_objects(addr, size);
3285   HeapWord* const end = addr + size;
3286   do {
3287     _start_array->allocate_block(addr);
3288     addr += cast_to_oop(addr)->size();
3289   } while (addr < end);
3290   return ParMarkBitMap::incomplete;
3291 }