1 /*
   2  * Copyright (c) 2005, 2016, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 #include "classfile/stringTable.hpp"
  27 #include "classfile/symbolTable.hpp"
  28 #include "classfile/systemDictionary.hpp"
  29 #include "code/codeCache.hpp"
  30 #include "gc/parallel/gcTaskManager.hpp"
  31 #include "gc/parallel/parallelScavengeHeap.inline.hpp"
  32 #include "gc/parallel/pcTasks.hpp"
  33 #include "gc/parallel/psAdaptiveSizePolicy.hpp"
  34 #include "gc/parallel/psCompactionManager.inline.hpp"
  35 #include "gc/parallel/psMarkSweep.hpp"
  36 #include "gc/parallel/psMarkSweepDecorator.hpp"
  37 #include "gc/parallel/psOldGen.hpp"
  38 #include "gc/parallel/psParallelCompact.inline.hpp"
  39 #include "gc/parallel/psPromotionManager.inline.hpp"
  40 #include "gc/parallel/psScavenge.hpp"
  41 #include "gc/parallel/psYoungGen.hpp"
  42 #include "gc/shared/gcCause.hpp"
  43 #include "gc/shared/gcHeapSummary.hpp"
  44 #include "gc/shared/gcId.hpp"
  45 #include "gc/shared/gcLocker.inline.hpp"
  46 #include "gc/shared/gcTimer.hpp"
  47 #include "gc/shared/gcTrace.hpp"
  48 #include "gc/shared/gcTraceTime.inline.hpp"
  49 #include "gc/shared/isGCActiveMark.hpp"
  50 #include "gc/shared/referencePolicy.hpp"
  51 #include "gc/shared/referenceProcessor.hpp"
  52 #include "gc/shared/spaceDecorator.hpp"
  53 #include "logging/log.hpp"
  54 #include "oops/instanceKlass.inline.hpp"
  55 #include "oops/instanceMirrorKlass.inline.hpp"
  56 #include "oops/methodData.hpp"
  57 #include "oops/objArrayKlass.inline.hpp"
  58 #include "oops/oop.inline.hpp"
  59 #include "runtime/atomic.inline.hpp"
  60 #include "runtime/fprofiler.hpp"
  61 #include "runtime/safepoint.hpp"
  62 #include "runtime/vmThread.hpp"
  63 #include "services/management.hpp"
  64 #include "services/memTracker.hpp"
  65 #include "services/memoryService.hpp"
  66 #include "utilities/events.hpp"
  67 #include "utilities/stack.inline.hpp"
  68 
  69 #include <math.h>
  70 
  71 // All sizes are in HeapWords.
  72 const size_t ParallelCompactData::Log2RegionSize  = 16; // 64K words
  73 const size_t ParallelCompactData::RegionSize      = (size_t)1 << Log2RegionSize;
  74 const size_t ParallelCompactData::RegionSizeBytes =
  75   RegionSize << LogHeapWordSize;
  76 const size_t ParallelCompactData::RegionSizeOffsetMask = RegionSize - 1;
  77 const size_t ParallelCompactData::RegionAddrOffsetMask = RegionSizeBytes - 1;
  78 const size_t ParallelCompactData::RegionAddrMask       = ~RegionAddrOffsetMask;
  79 
  80 const size_t ParallelCompactData::Log2BlockSize   = 7; // 128 words
  81 const size_t ParallelCompactData::BlockSize       = (size_t)1 << Log2BlockSize;
  82 const size_t ParallelCompactData::BlockSizeBytes  =
  83   BlockSize << LogHeapWordSize;
  84 const size_t ParallelCompactData::BlockSizeOffsetMask = BlockSize - 1;
  85 const size_t ParallelCompactData::BlockAddrOffsetMask = BlockSizeBytes - 1;
  86 const size_t ParallelCompactData::BlockAddrMask       = ~BlockAddrOffsetMask;
  87 
  88 const size_t ParallelCompactData::BlocksPerRegion = RegionSize / BlockSize;
  89 const size_t ParallelCompactData::Log2BlocksPerRegion =
  90   Log2RegionSize - Log2BlockSize;
  91 
  92 const ParallelCompactData::RegionData::region_sz_t
  93 ParallelCompactData::RegionData::dc_shift = 27;
  94 
  95 const ParallelCompactData::RegionData::region_sz_t
  96 ParallelCompactData::RegionData::dc_mask = ~0U << dc_shift;
  97 
  98 const ParallelCompactData::RegionData::region_sz_t
  99 ParallelCompactData::RegionData::dc_one = 0x1U << dc_shift;
 100 
 101 const ParallelCompactData::RegionData::region_sz_t
 102 ParallelCompactData::RegionData::los_mask = ~dc_mask;
 103 
 104 const ParallelCompactData::RegionData::region_sz_t
 105 ParallelCompactData::RegionData::dc_claimed = 0x8U << dc_shift;
 106 
 107 const ParallelCompactData::RegionData::region_sz_t
 108 ParallelCompactData::RegionData::dc_completed = 0xcU << dc_shift;
 109 
 110 SpaceInfo PSParallelCompact::_space_info[PSParallelCompact::last_space_id];
 111 
 112 ReferenceProcessor* PSParallelCompact::_ref_processor = NULL;
 113 
 114 double PSParallelCompact::_dwl_mean;
 115 double PSParallelCompact::_dwl_std_dev;
 116 double PSParallelCompact::_dwl_first_term;
 117 double PSParallelCompact::_dwl_adjustment;
 118 #ifdef  ASSERT
 119 bool   PSParallelCompact::_dwl_initialized = false;
 120 #endif  // #ifdef ASSERT
 121 
 122 void SplitInfo::record(size_t src_region_idx, size_t partial_obj_size,
 123                        HeapWord* destination)
 124 {
 125   assert(src_region_idx != 0, "invalid src_region_idx");
 126   assert(partial_obj_size != 0, "invalid partial_obj_size argument");
 127   assert(destination != NULL, "invalid destination argument");
 128 
 129   _src_region_idx = src_region_idx;
 130   _partial_obj_size = partial_obj_size;
 131   _destination = destination;
 132 
 133   // These fields may not be updated below, so make sure they're clear.
 134   assert(_dest_region_addr == NULL, "should have been cleared");
 135   assert(_first_src_addr == NULL, "should have been cleared");
 136 
 137   // Determine the number of destination regions for the partial object.
 138   HeapWord* const last_word = destination + partial_obj_size - 1;
 139   const ParallelCompactData& sd = PSParallelCompact::summary_data();
 140   HeapWord* const beg_region_addr = sd.region_align_down(destination);
 141   HeapWord* const end_region_addr = sd.region_align_down(last_word);
 142 
 143   if (beg_region_addr == end_region_addr) {
 144     // One destination region.
 145     _destination_count = 1;
 146     if (end_region_addr == destination) {
 147       // The destination falls on a region boundary, thus the first word of the
 148       // partial object will be the first word copied to the destination region.
 149       _dest_region_addr = end_region_addr;
 150       _first_src_addr = sd.region_to_addr(src_region_idx);
 151     }
 152   } else {
 153     // Two destination regions.  When copied, the partial object will cross a
 154     // destination region boundary, so a word somewhere within the partial
 155     // object will be the first word copied to the second destination region.
 156     _destination_count = 2;
 157     _dest_region_addr = end_region_addr;
 158     const size_t ofs = pointer_delta(end_region_addr, destination);
 159     assert(ofs < _partial_obj_size, "sanity");
 160     _first_src_addr = sd.region_to_addr(src_region_idx) + ofs;
 161   }
 162 }
 163 
 164 void SplitInfo::clear()
 165 {
 166   _src_region_idx = 0;
 167   _partial_obj_size = 0;
 168   _destination = NULL;
 169   _destination_count = 0;
 170   _dest_region_addr = NULL;
 171   _first_src_addr = NULL;
 172   assert(!is_valid(), "sanity");
 173 }
 174 
 175 #ifdef  ASSERT
 176 void SplitInfo::verify_clear()
 177 {
 178   assert(_src_region_idx == 0, "not clear");
 179   assert(_partial_obj_size == 0, "not clear");
 180   assert(_destination == NULL, "not clear");
 181   assert(_destination_count == 0, "not clear");
 182   assert(_dest_region_addr == NULL, "not clear");
 183   assert(_first_src_addr == NULL, "not clear");
 184 }
 185 #endif  // #ifdef ASSERT
 186 
 187 
 188 void PSParallelCompact::print_on_error(outputStream* st) {
 189   _mark_bitmap.print_on_error(st);
 190 }
 191 
 192 #ifndef PRODUCT
 193 const char* PSParallelCompact::space_names[] = {
 194   "old ", "eden", "from", "to  "
 195 };
 196 
 197 void PSParallelCompact::print_region_ranges() {
 198   if (!log_develop_is_enabled(Trace, gc, compaction, phases)) {
 199     return;
 200   }
 201   LogHandle(gc, compaction, phases) log;
 202   ResourceMark rm;
 203   Universe::print_on(log.trace_stream());
 204   log.trace("space  bottom     top        end        new_top");
 205   log.trace("------ ---------- ---------- ---------- ----------");
 206 
 207   for (unsigned int id = 0; id < last_space_id; ++id) {
 208     const MutableSpace* space = _space_info[id].space();
 209     log.trace("%u %s "
 210               SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " "
 211               SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " ",
 212               id, space_names[id],
 213               summary_data().addr_to_region_idx(space->bottom()),
 214               summary_data().addr_to_region_idx(space->top()),
 215               summary_data().addr_to_region_idx(space->end()),
 216               summary_data().addr_to_region_idx(_space_info[id].new_top()));
 217   }
 218 }
 219 
 220 void
 221 print_generic_summary_region(size_t i, const ParallelCompactData::RegionData* c)
 222 {
 223 #define REGION_IDX_FORMAT        SIZE_FORMAT_W(7)
 224 #define REGION_DATA_FORMAT       SIZE_FORMAT_W(5)
 225 
 226   ParallelCompactData& sd = PSParallelCompact::summary_data();
 227   size_t dci = c->destination() ? sd.addr_to_region_idx(c->destination()) : 0;
 228   log_develop_trace(gc, compaction, phases)(
 229       REGION_IDX_FORMAT " " PTR_FORMAT " "
 230       REGION_IDX_FORMAT " " PTR_FORMAT " "
 231       REGION_DATA_FORMAT " " REGION_DATA_FORMAT " "
 232       REGION_DATA_FORMAT " " REGION_IDX_FORMAT " %d",
 233       i, p2i(c->data_location()), dci, p2i(c->destination()),
 234       c->partial_obj_size(), c->live_obj_size(),
 235       c->data_size(), c->source_region(), c->destination_count());
 236 
 237 #undef  REGION_IDX_FORMAT
 238 #undef  REGION_DATA_FORMAT
 239 }
 240 
 241 void
 242 print_generic_summary_data(ParallelCompactData& summary_data,
 243                            HeapWord* const beg_addr,
 244                            HeapWord* const end_addr)
 245 {
 246   size_t total_words = 0;
 247   size_t i = summary_data.addr_to_region_idx(beg_addr);
 248   const size_t last = summary_data.addr_to_region_idx(end_addr);
 249   HeapWord* pdest = 0;
 250 
 251   while (i <= last) {
 252     ParallelCompactData::RegionData* c = summary_data.region(i);
 253     if (c->data_size() != 0 || c->destination() != pdest) {
 254       print_generic_summary_region(i, c);
 255       total_words += c->data_size();
 256       pdest = c->destination();
 257     }
 258     ++i;
 259   }
 260 
 261   log_develop_trace(gc, compaction, phases)("summary_data_bytes=" SIZE_FORMAT, total_words * HeapWordSize);
 262 }
 263 
 264 void
 265 print_generic_summary_data(ParallelCompactData& summary_data,
 266                            SpaceInfo* space_info)
 267 {
 268   if (!log_develop_is_enabled(Trace, gc, compaction, phases)) {
 269     return;
 270   }
 271 
 272   for (unsigned int id = 0; id < PSParallelCompact::last_space_id; ++id) {
 273     const MutableSpace* space = space_info[id].space();
 274     print_generic_summary_data(summary_data, space->bottom(),
 275                                MAX2(space->top(), space_info[id].new_top()));
 276   }
 277 }
 278 
 279 void
 280 print_initial_summary_data(ParallelCompactData& summary_data,
 281                            const MutableSpace* space) {
 282   if (space->top() == space->bottom()) {
 283     return;
 284   }
 285 
 286   const size_t region_size = ParallelCompactData::RegionSize;
 287   typedef ParallelCompactData::RegionData RegionData;
 288   HeapWord* const top_aligned_up = summary_data.region_align_up(space->top());
 289   const size_t end_region = summary_data.addr_to_region_idx(top_aligned_up);
 290   const RegionData* c = summary_data.region(end_region - 1);
 291   HeapWord* end_addr = c->destination() + c->data_size();
 292   const size_t live_in_space = pointer_delta(end_addr, space->bottom());
 293 
 294   // Print (and count) the full regions at the beginning of the space.
 295   size_t full_region_count = 0;
 296   size_t i = summary_data.addr_to_region_idx(space->bottom());
 297   while (i < end_region && summary_data.region(i)->data_size() == region_size) {
 298     ParallelCompactData::RegionData* c = summary_data.region(i);
 299     log_develop_trace(gc, compaction, phases)(
 300         SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d",
 301         i, p2i(c->destination()),
 302         c->partial_obj_size(), c->live_obj_size(),
 303         c->data_size(), c->source_region(), c->destination_count());
 304     ++full_region_count;
 305     ++i;
 306   }
 307 
 308   size_t live_to_right = live_in_space - full_region_count * region_size;
 309 
 310   double max_reclaimed_ratio = 0.0;
 311   size_t max_reclaimed_ratio_region = 0;
 312   size_t max_dead_to_right = 0;
 313   size_t max_live_to_right = 0;
 314 
 315   // Print the 'reclaimed ratio' for regions while there is something live in
 316   // the region or to the right of it.  The remaining regions are empty (and
 317   // uninteresting), and computing the ratio will result in division by 0.
 318   while (i < end_region && live_to_right > 0) {
 319     c = summary_data.region(i);
 320     HeapWord* const region_addr = summary_data.region_to_addr(i);
 321     const size_t used_to_right = pointer_delta(space->top(), region_addr);
 322     const size_t dead_to_right = used_to_right - live_to_right;
 323     const double reclaimed_ratio = double(dead_to_right) / live_to_right;
 324 
 325     if (reclaimed_ratio > max_reclaimed_ratio) {
 326             max_reclaimed_ratio = reclaimed_ratio;
 327             max_reclaimed_ratio_region = i;
 328             max_dead_to_right = dead_to_right;
 329             max_live_to_right = live_to_right;
 330     }
 331 
 332     ParallelCompactData::RegionData* c = summary_data.region(i);
 333     log_develop_trace(gc, compaction, phases)(
 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         "%12.10f " SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10),
 336         i, p2i(c->destination()),
 337         c->partial_obj_size(), c->live_obj_size(),
 338         c->data_size(), c->source_region(), c->destination_count(),
 339         reclaimed_ratio, dead_to_right, live_to_right);
 340 
 341 
 342     live_to_right -= c->data_size();
 343     ++i;
 344   }
 345 
 346   // Any remaining regions are empty.  Print one more if there is one.
 347   if (i < end_region) {
 348     ParallelCompactData::RegionData* c = summary_data.region(i);
 349     log_develop_trace(gc, compaction, phases)(
 350         SIZE_FORMAT_W(5) " " PTR_FORMAT " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d",
 351          i, p2i(c->destination()),
 352          c->partial_obj_size(), c->live_obj_size(),
 353          c->data_size(), c->source_region(), c->destination_count());
 354   }
 355 
 356   log_develop_trace(gc, compaction, phases)("max:  " SIZE_FORMAT_W(4) " d2r=" SIZE_FORMAT_W(10) " l2r=" SIZE_FORMAT_W(10) " max_ratio=%14.12f",
 357                                             max_reclaimed_ratio_region, max_dead_to_right, max_live_to_right, max_reclaimed_ratio);
 358 }
 359 
 360 void
 361 print_initial_summary_data(ParallelCompactData& summary_data,
 362                            SpaceInfo* space_info) {
 363   if (!log_develop_is_enabled(Trace, gc, compaction, phases)) {
 364     return;
 365   }
 366 
 367   unsigned int id = PSParallelCompact::old_space_id;
 368   const MutableSpace* space;
 369   do {
 370     space = space_info[id].space();
 371     print_initial_summary_data(summary_data, space);
 372   } while (++id < PSParallelCompact::eden_space_id);
 373 
 374   do {
 375     space = space_info[id].space();
 376     print_generic_summary_data(summary_data, space->bottom(), space->top());
 377   } while (++id < PSParallelCompact::last_space_id);
 378 }
 379 #endif  // #ifndef PRODUCT
 380 
 381 #ifdef  ASSERT
 382 size_t add_obj_count;
 383 size_t add_obj_size;
 384 size_t mark_bitmap_count;
 385 size_t mark_bitmap_size;
 386 #endif  // #ifdef ASSERT
 387 
 388 ParallelCompactData::ParallelCompactData()
 389 {
 390   _region_start = 0;
 391 
 392   _region_vspace = 0;
 393   _reserved_byte_size = 0;
 394   _region_data = 0;
 395   _region_count = 0;
 396 
 397   _block_vspace = 0;
 398   _block_data = 0;
 399   _block_count = 0;
 400 }
 401 
 402 bool ParallelCompactData::initialize(MemRegion covered_region)
 403 {
 404   _region_start = covered_region.start();
 405   const size_t region_size = covered_region.word_size();
 406   DEBUG_ONLY(_region_end = _region_start + region_size;)
 407 
 408   assert(region_align_down(_region_start) == _region_start,
 409          "region start not aligned");
 410   assert((region_size & RegionSizeOffsetMask) == 0,
 411          "region size not a multiple of RegionSize");
 412 
 413   bool result = initialize_region_data(region_size) && initialize_block_data();
 414   return result;
 415 }
 416 
 417 PSVirtualSpace*
 418 ParallelCompactData::create_vspace(size_t count, size_t element_size)
 419 {
 420   const size_t raw_bytes = count * element_size;
 421   const size_t page_sz = os::page_size_for_region_aligned(raw_bytes, 10);
 422   const size_t granularity = os::vm_allocation_granularity();
 423   _reserved_byte_size = align_size_up(raw_bytes, MAX2(page_sz, granularity));
 424 
 425   const size_t rs_align = page_sz == (size_t) os::vm_page_size() ? 0 :
 426     MAX2(page_sz, granularity);
 427   ReservedSpace rs(_reserved_byte_size, rs_align, rs_align > 0);
 428   os::trace_page_sizes("par compact", raw_bytes, raw_bytes, page_sz, rs.base(),
 429                        rs.size());
 430 
 431   MemTracker::record_virtual_memory_type((address)rs.base(), mtGC);
 432 
 433   PSVirtualSpace* vspace = new PSVirtualSpace(rs, page_sz);
 434   if (vspace != 0) {
 435     if (vspace->expand_by(_reserved_byte_size)) {
 436       return vspace;
 437     }
 438     delete vspace;
 439     // Release memory reserved in the space.
 440     rs.release();
 441   }
 442 
 443   return 0;
 444 }
 445 
 446 bool ParallelCompactData::initialize_region_data(size_t region_size)
 447 {
 448   const size_t count = (region_size + RegionSizeOffsetMask) >> Log2RegionSize;
 449   _region_vspace = create_vspace(count, sizeof(RegionData));
 450   if (_region_vspace != 0) {
 451     _region_data = (RegionData*)_region_vspace->reserved_low_addr();
 452     _region_count = count;
 453     return true;
 454   }
 455   return false;
 456 }
 457 
 458 bool ParallelCompactData::initialize_block_data()
 459 {
 460   assert(_region_count != 0, "region data must be initialized first");
 461   const size_t count = _region_count << Log2BlocksPerRegion;
 462   _block_vspace = create_vspace(count, sizeof(BlockData));
 463   if (_block_vspace != 0) {
 464     _block_data = (BlockData*)_block_vspace->reserved_low_addr();
 465     _block_count = count;
 466     return true;
 467   }
 468   return false;
 469 }
 470 
 471 void ParallelCompactData::clear()
 472 {
 473   memset(_region_data, 0, _region_vspace->committed_size());
 474   memset(_block_data, 0, _block_vspace->committed_size());
 475 }
 476 
 477 void ParallelCompactData::clear_range(size_t beg_region, size_t end_region) {
 478   assert(beg_region <= _region_count, "beg_region out of range");
 479   assert(end_region <= _region_count, "end_region out of range");
 480   assert(RegionSize % BlockSize == 0, "RegionSize not a multiple of BlockSize");
 481 
 482   const size_t region_cnt = end_region - beg_region;
 483   memset(_region_data + beg_region, 0, region_cnt * sizeof(RegionData));
 484 
 485   const size_t beg_block = beg_region * BlocksPerRegion;
 486   const size_t block_cnt = region_cnt * BlocksPerRegion;
 487   memset(_block_data + beg_block, 0, block_cnt * sizeof(BlockData));
 488 }
 489 
 490 HeapWord* ParallelCompactData::partial_obj_end(size_t region_idx) const
 491 {
 492   const RegionData* cur_cp = region(region_idx);
 493   const RegionData* const end_cp = region(region_count() - 1);
 494 
 495   HeapWord* result = region_to_addr(region_idx);
 496   if (cur_cp < end_cp) {
 497     do {
 498       result += cur_cp->partial_obj_size();
 499     } while (cur_cp->partial_obj_size() == RegionSize && ++cur_cp < end_cp);
 500   }
 501   return result;
 502 }
 503 
 504 void ParallelCompactData::add_obj(HeapWord* addr, size_t len)
 505 {
 506   const size_t obj_ofs = pointer_delta(addr, _region_start);
 507   const size_t beg_region = obj_ofs >> Log2RegionSize;
 508   const size_t end_region = (obj_ofs + len - 1) >> Log2RegionSize;
 509 
 510   DEBUG_ONLY(Atomic::inc_ptr(&add_obj_count);)
 511   DEBUG_ONLY(Atomic::add_ptr(len, &add_obj_size);)
 512 
 513   if (beg_region == end_region) {
 514     // All in one region.
 515     _region_data[beg_region].add_live_obj(len);
 516     return;
 517   }
 518 
 519   // First region.
 520   const size_t beg_ofs = region_offset(addr);
 521   _region_data[beg_region].add_live_obj(RegionSize - beg_ofs);
 522 
 523   Klass* klass = ((oop)addr)->klass();
 524   // Middle regions--completely spanned by this object.
 525   for (size_t region = beg_region + 1; region < end_region; ++region) {
 526     _region_data[region].set_partial_obj_size(RegionSize);
 527     _region_data[region].set_partial_obj_addr(addr);
 528   }
 529 
 530   // Last region.
 531   const size_t end_ofs = region_offset(addr + len - 1);
 532   _region_data[end_region].set_partial_obj_size(end_ofs + 1);
 533   _region_data[end_region].set_partial_obj_addr(addr);
 534 }
 535 
 536 void
 537 ParallelCompactData::summarize_dense_prefix(HeapWord* beg, HeapWord* end)
 538 {
 539   assert(region_offset(beg) == 0, "not RegionSize aligned");
 540   assert(region_offset(end) == 0, "not RegionSize aligned");
 541 
 542   size_t cur_region = addr_to_region_idx(beg);
 543   const size_t end_region = addr_to_region_idx(end);
 544   HeapWord* addr = beg;
 545   while (cur_region < end_region) {
 546     _region_data[cur_region].set_destination(addr);
 547     _region_data[cur_region].set_destination_count(0);
 548     _region_data[cur_region].set_source_region(cur_region);
 549     _region_data[cur_region].set_data_location(addr);
 550 
 551     // Update live_obj_size so the region appears completely full.
 552     size_t live_size = RegionSize - _region_data[cur_region].partial_obj_size();
 553     _region_data[cur_region].set_live_obj_size(live_size);
 554 
 555     ++cur_region;
 556     addr += RegionSize;
 557   }
 558 }
 559 
 560 // Find the point at which a space can be split and, if necessary, record the
 561 // split point.
 562 //
 563 // If the current src region (which overflowed the destination space) doesn't
 564 // have a partial object, the split point is at the beginning of the current src
 565 // region (an "easy" split, no extra bookkeeping required).
 566 //
 567 // If the current src region has a partial object, the split point is in the
 568 // region where that partial object starts (call it the split_region).  If
 569 // split_region has a partial object, then the split point is just after that
 570 // partial object (a "hard" split where we have to record the split data and
 571 // zero the partial_obj_size field).  With a "hard" split, we know that the
 572 // partial_obj ends within split_region because the partial object that caused
 573 // the overflow starts in split_region.  If split_region doesn't have a partial
 574 // obj, then the split is at the beginning of split_region (another "easy"
 575 // split).
 576 HeapWord*
 577 ParallelCompactData::summarize_split_space(size_t src_region,
 578                                            SplitInfo& split_info,
 579                                            HeapWord* destination,
 580                                            HeapWord* target_end,
 581                                            HeapWord** target_next)
 582 {
 583   assert(destination <= target_end, "sanity");
 584   assert(destination + _region_data[src_region].data_size() > target_end,
 585     "region should not fit into target space");
 586   assert(is_region_aligned(target_end), "sanity");
 587 
 588   size_t split_region = src_region;
 589   HeapWord* split_destination = destination;
 590   size_t partial_obj_size = _region_data[src_region].partial_obj_size();
 591 
 592   if (destination + partial_obj_size > target_end) {
 593     // The split point is just after the partial object (if any) in the
 594     // src_region that contains the start of the object that overflowed the
 595     // destination space.
 596     //
 597     // Find the start of the "overflow" object and set split_region to the
 598     // region containing it.
 599     HeapWord* const overflow_obj = _region_data[src_region].partial_obj_addr();
 600     split_region = addr_to_region_idx(overflow_obj);
 601 
 602     // Clear the source_region field of all destination regions whose first word
 603     // came from data after the split point (a non-null source_region field
 604     // implies a region must be filled).
 605     //
 606     // An alternative to the simple loop below:  clear during post_compact(),
 607     // which uses memcpy instead of individual stores, and is easy to
 608     // parallelize.  (The downside is that it clears the entire RegionData
 609     // object as opposed to just one field.)
 610     //
 611     // post_compact() would have to clear the summary data up to the highest
 612     // address that was written during the summary phase, which would be
 613     //
 614     //         max(top, max(new_top, clear_top))
 615     //
 616     // where clear_top is a new field in SpaceInfo.  Would have to set clear_top
 617     // to target_end.
 618     const RegionData* const sr = region(split_region);
 619     const size_t beg_idx =
 620       addr_to_region_idx(region_align_up(sr->destination() +
 621                                          sr->partial_obj_size()));
 622     const size_t end_idx = addr_to_region_idx(target_end);
 623 
 624     log_develop_trace(gc, compaction, phases)("split:  clearing source_region field in [" SIZE_FORMAT ", " SIZE_FORMAT ")", beg_idx, end_idx);
 625     for (size_t idx = beg_idx; idx < end_idx; ++idx) {
 626       _region_data[idx].set_source_region(0);
 627     }
 628 
 629     // Set split_destination and partial_obj_size to reflect the split region.
 630     split_destination = sr->destination();
 631     partial_obj_size = sr->partial_obj_size();
 632   }
 633 
 634   // The split is recorded only if a partial object extends onto the region.
 635   if (partial_obj_size != 0) {
 636     _region_data[split_region].set_partial_obj_size(0);
 637     split_info.record(split_region, partial_obj_size, split_destination);
 638   }
 639 
 640   // Setup the continuation addresses.
 641   *target_next = split_destination + partial_obj_size;
 642   HeapWord* const source_next = region_to_addr(split_region) + partial_obj_size;
 643 
 644   if (log_develop_is_enabled(Trace, gc, compaction, phases)) {
 645     const char * split_type = partial_obj_size == 0 ? "easy" : "hard";
 646     log_develop_trace(gc, compaction, phases)("%s split:  src=" PTR_FORMAT " src_c=" SIZE_FORMAT " pos=" SIZE_FORMAT,
 647                                               split_type, p2i(source_next), split_region, partial_obj_size);
 648     log_develop_trace(gc, compaction, phases)("%s split:  dst=" PTR_FORMAT " dst_c=" SIZE_FORMAT " tn=" PTR_FORMAT,
 649                                               split_type, p2i(split_destination),
 650                                               addr_to_region_idx(split_destination),
 651                                               p2i(*target_next));
 652 
 653     if (partial_obj_size != 0) {
 654       HeapWord* const po_beg = split_info.destination();
 655       HeapWord* const po_end = po_beg + split_info.partial_obj_size();
 656       log_develop_trace(gc, compaction, phases)("%s split:  po_beg=" PTR_FORMAT " " SIZE_FORMAT " po_end=" PTR_FORMAT " " SIZE_FORMAT,
 657                                                 split_type,
 658                                                 p2i(po_beg), addr_to_region_idx(po_beg),
 659                                                 p2i(po_end), addr_to_region_idx(po_end));
 660     }
 661   }
 662 
 663   return source_next;
 664 }
 665 
 666 bool ParallelCompactData::summarize(SplitInfo& split_info,
 667                                     HeapWord* source_beg, HeapWord* source_end,
 668                                     HeapWord** source_next,
 669                                     HeapWord* target_beg, HeapWord* target_end,
 670                                     HeapWord** target_next)
 671 {
 672   HeapWord* const source_next_val = source_next == NULL ? NULL : *source_next;
 673   log_develop_trace(gc, compaction, phases)(
 674       "sb=" PTR_FORMAT " se=" PTR_FORMAT " sn=" PTR_FORMAT
 675       "tb=" PTR_FORMAT " te=" PTR_FORMAT " tn=" PTR_FORMAT,
 676       p2i(source_beg), p2i(source_end), p2i(source_next_val),
 677       p2i(target_beg), p2i(target_end), p2i(*target_next));
 678 
 679   size_t cur_region = addr_to_region_idx(source_beg);
 680   const size_t end_region = addr_to_region_idx(region_align_up(source_end));
 681 
 682   HeapWord *dest_addr = target_beg;
 683   while (cur_region < end_region) {
 684     // The destination must be set even if the region has no data.
 685     _region_data[cur_region].set_destination(dest_addr);
 686 
 687     size_t words = _region_data[cur_region].data_size();
 688     if (words > 0) {
 689       // If cur_region does not fit entirely into the target space, find a point
 690       // at which the source space can be 'split' so that part is copied to the
 691       // target space and the rest is copied elsewhere.
 692       if (dest_addr + words > target_end) {
 693         assert(source_next != NULL, "source_next is NULL when splitting");
 694         *source_next = summarize_split_space(cur_region, split_info, dest_addr,
 695                                              target_end, target_next);
 696         return false;
 697       }
 698 
 699       // Compute the destination_count for cur_region, and if necessary, update
 700       // source_region for a destination region.  The source_region field is
 701       // updated if cur_region is the first (left-most) region to be copied to a
 702       // destination region.
 703       //
 704       // The destination_count calculation is a bit subtle.  A region that has
 705       // data that compacts into itself does not count itself as a destination.
 706       // This maintains the invariant that a zero count means the region is
 707       // available and can be claimed and then filled.
 708       uint destination_count = 0;
 709       if (split_info.is_split(cur_region)) {
 710         // The current region has been split:  the partial object will be copied
 711         // to one destination space and the remaining data will be copied to
 712         // another destination space.  Adjust the initial destination_count and,
 713         // if necessary, set the source_region field if the partial object will
 714         // cross a destination region boundary.
 715         destination_count = split_info.destination_count();
 716         if (destination_count == 2) {
 717           size_t dest_idx = addr_to_region_idx(split_info.dest_region_addr());
 718           _region_data[dest_idx].set_source_region(cur_region);
 719         }
 720       }
 721 
 722       HeapWord* const last_addr = dest_addr + words - 1;
 723       const size_t dest_region_1 = addr_to_region_idx(dest_addr);
 724       const size_t dest_region_2 = addr_to_region_idx(last_addr);
 725 
 726       // Initially assume that the destination regions will be the same and
 727       // adjust the value below if necessary.  Under this assumption, if
 728       // cur_region == dest_region_2, then cur_region will be compacted
 729       // completely into itself.
 730       destination_count += cur_region == dest_region_2 ? 0 : 1;
 731       if (dest_region_1 != dest_region_2) {
 732         // Destination regions differ; adjust destination_count.
 733         destination_count += 1;
 734         // Data from cur_region will be copied to the start of dest_region_2.
 735         _region_data[dest_region_2].set_source_region(cur_region);
 736       } else if (region_offset(dest_addr) == 0) {
 737         // Data from cur_region will be copied to the start of the destination
 738         // region.
 739         _region_data[dest_region_1].set_source_region(cur_region);
 740       }
 741 
 742       _region_data[cur_region].set_destination_count(destination_count);
 743       _region_data[cur_region].set_data_location(region_to_addr(cur_region));
 744       dest_addr += words;
 745     }
 746 
 747     ++cur_region;
 748   }
 749 
 750   *target_next = dest_addr;
 751   return true;
 752 }
 753 
 754 HeapWord* ParallelCompactData::calc_new_pointer(HeapWord* addr, ParCompactionManager* cm) {
 755   assert(addr != NULL, "Should detect NULL oop earlier");
 756   assert(ParallelScavengeHeap::heap()->is_in(addr), "not in heap");
 757   assert(PSParallelCompact::mark_bitmap()->is_marked(addr), "not marked");
 758 
 759   // Region covering the object.
 760   RegionData* const region_ptr = addr_to_region_ptr(addr);
 761   HeapWord* result = region_ptr->destination();
 762 
 763   // If the entire Region is live, the new location is region->destination + the
 764   // offset of the object within in the Region.
 765 
 766   // Run some performance tests to determine if this special case pays off.  It
 767   // is worth it for pointers into the dense prefix.  If the optimization to
 768   // avoid pointer updates in regions that only point to the dense prefix is
 769   // ever implemented, this should be revisited.
 770   if (region_ptr->data_size() == RegionSize) {
 771     result += region_offset(addr);
 772     return result;
 773   }
 774 
 775   // Otherwise, the new location is region->destination + block offset + the
 776   // number of live words in the Block that are (a) to the left of addr and (b)
 777   // due to objects that start in the Block.
 778 
 779   // Fill in the block table if necessary.  This is unsynchronized, so multiple
 780   // threads may fill the block table for a region (harmless, since it is
 781   // idempotent).
 782   if (!region_ptr->blocks_filled()) {
 783     PSParallelCompact::fill_blocks(addr_to_region_idx(addr));
 784     region_ptr->set_blocks_filled();
 785   }
 786 
 787   HeapWord* const search_start = block_align_down(addr);
 788   const size_t block_offset = addr_to_block_ptr(addr)->offset();
 789 
 790   const ParMarkBitMap* bitmap = PSParallelCompact::mark_bitmap();
 791   const size_t live = bitmap->live_words_in_range(cm, search_start, oop(addr));
 792   result += block_offset + live;
 793   DEBUG_ONLY(PSParallelCompact::check_new_location(addr, result));
 794   return result;
 795 }
 796 
 797 #ifdef ASSERT
 798 void ParallelCompactData::verify_clear(const PSVirtualSpace* vspace)
 799 {
 800   const size_t* const beg = (const size_t*)vspace->committed_low_addr();
 801   const size_t* const end = (const size_t*)vspace->committed_high_addr();
 802   for (const size_t* p = beg; p < end; ++p) {
 803     assert(*p == 0, "not zero");
 804   }
 805 }
 806 
 807 void ParallelCompactData::verify_clear()
 808 {
 809   verify_clear(_region_vspace);
 810   verify_clear(_block_vspace);
 811 }
 812 #endif  // #ifdef ASSERT
 813 
 814 STWGCTimer          PSParallelCompact::_gc_timer;
 815 ParallelOldTracer   PSParallelCompact::_gc_tracer;
 816 elapsedTimer        PSParallelCompact::_accumulated_time;
 817 unsigned int        PSParallelCompact::_total_invocations = 0;
 818 unsigned int        PSParallelCompact::_maximum_compaction_gc_num = 0;
 819 jlong               PSParallelCompact::_time_of_last_gc = 0;
 820 CollectorCounters*  PSParallelCompact::_counters = NULL;
 821 ParMarkBitMap       PSParallelCompact::_mark_bitmap;
 822 ParallelCompactData PSParallelCompact::_summary_data;
 823 
 824 PSParallelCompact::IsAliveClosure PSParallelCompact::_is_alive_closure;
 825 
 826 bool PSParallelCompact::IsAliveClosure::do_object_b(oop p) { return mark_bitmap()->is_marked(p); }
 827 
 828 void PSParallelCompact::AdjustKlassClosure::do_klass(Klass* klass) {
 829   PSParallelCompact::AdjustPointerClosure closure(_cm);
 830   klass->oops_do(&closure);
 831 }
 832 
 833 void PSParallelCompact::post_initialize() {
 834   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
 835   MemRegion mr = heap->reserved_region();
 836   _ref_processor =
 837     new ReferenceProcessor(mr,            // span
 838                            ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing
 839                            ParallelGCThreads, // mt processing degree
 840                            true,              // mt discovery
 841                            ParallelGCThreads, // mt discovery degree
 842                            true,              // atomic_discovery
 843                            &_is_alive_closure); // non-header is alive closure
 844   _counters = new CollectorCounters("PSParallelCompact", 1);
 845 
 846   // Initialize static fields in ParCompactionManager.
 847   ParCompactionManager::initialize(mark_bitmap());
 848 }
 849 
 850 bool PSParallelCompact::initialize() {
 851   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
 852   MemRegion mr = heap->reserved_region();
 853 
 854   // Was the old gen get allocated successfully?
 855   if (!heap->old_gen()->is_allocated()) {
 856     return false;
 857   }
 858 
 859   initialize_space_info();
 860   initialize_dead_wood_limiter();
 861 
 862   if (!_mark_bitmap.initialize(mr)) {
 863     vm_shutdown_during_initialization(
 864       err_msg("Unable to allocate " SIZE_FORMAT "KB bitmaps for parallel "
 865       "garbage collection for the requested " SIZE_FORMAT "KB heap.",
 866       _mark_bitmap.reserved_byte_size()/K, mr.byte_size()/K));
 867     return false;
 868   }
 869 
 870   if (!_summary_data.initialize(mr)) {
 871     vm_shutdown_during_initialization(
 872       err_msg("Unable to allocate " SIZE_FORMAT "KB card tables for parallel "
 873       "garbage collection for the requested " SIZE_FORMAT "KB heap.",
 874       _summary_data.reserved_byte_size()/K, mr.byte_size()/K));
 875     return false;
 876   }
 877 
 878   return true;
 879 }
 880 
 881 void PSParallelCompact::initialize_space_info()
 882 {
 883   memset(&_space_info, 0, sizeof(_space_info));
 884 
 885   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
 886   PSYoungGen* young_gen = heap->young_gen();
 887 
 888   _space_info[old_space_id].set_space(heap->old_gen()->object_space());
 889   _space_info[eden_space_id].set_space(young_gen->eden_space());
 890   _space_info[from_space_id].set_space(young_gen->from_space());
 891   _space_info[to_space_id].set_space(young_gen->to_space());
 892 
 893   _space_info[old_space_id].set_start_array(heap->old_gen()->start_array());
 894 }
 895 
 896 void PSParallelCompact::initialize_dead_wood_limiter()
 897 {
 898   const size_t max = 100;
 899   _dwl_mean = double(MIN2(ParallelOldDeadWoodLimiterMean, max)) / 100.0;
 900   _dwl_std_dev = double(MIN2(ParallelOldDeadWoodLimiterStdDev, max)) / 100.0;
 901   _dwl_first_term = 1.0 / (sqrt(2.0 * M_PI) * _dwl_std_dev);
 902   DEBUG_ONLY(_dwl_initialized = true;)
 903   _dwl_adjustment = normal_distribution(1.0);
 904 }
 905 
 906 void
 907 PSParallelCompact::clear_data_covering_space(SpaceId id)
 908 {
 909   // At this point, top is the value before GC, new_top() is the value that will
 910   // be set at the end of GC.  The marking bitmap is cleared to top; nothing
 911   // should be marked above top.  The summary data is cleared to the larger of
 912   // top & new_top.
 913   MutableSpace* const space = _space_info[id].space();
 914   HeapWord* const bot = space->bottom();
 915   HeapWord* const top = space->top();
 916   HeapWord* const max_top = MAX2(top, _space_info[id].new_top());
 917 
 918   const idx_t beg_bit = _mark_bitmap.addr_to_bit(bot);
 919   const idx_t end_bit = BitMap::word_align_up(_mark_bitmap.addr_to_bit(top));
 920   _mark_bitmap.clear_range(beg_bit, end_bit);
 921 
 922   const size_t beg_region = _summary_data.addr_to_region_idx(bot);
 923   const size_t end_region =
 924     _summary_data.addr_to_region_idx(_summary_data.region_align_up(max_top));
 925   _summary_data.clear_range(beg_region, end_region);
 926 
 927   // Clear the data used to 'split' regions.
 928   SplitInfo& split_info = _space_info[id].split_info();
 929   if (split_info.is_valid()) {
 930     split_info.clear();
 931   }
 932   DEBUG_ONLY(split_info.verify_clear();)
 933 }
 934 
 935 void PSParallelCompact::pre_compact()
 936 {
 937   // Update the from & to space pointers in space_info, since they are swapped
 938   // at each young gen gc.  Do the update unconditionally (even though a
 939   // promotion failure does not swap spaces) because an unknown number of young
 940   // collections will have swapped the spaces an unknown number of times.
 941   GCTraceTime(Trace, gc, phases) tm("Pre Compact", &_gc_timer);
 942   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
 943   _space_info[from_space_id].set_space(heap->young_gen()->from_space());
 944   _space_info[to_space_id].set_space(heap->young_gen()->to_space());
 945 
 946   DEBUG_ONLY(add_obj_count = add_obj_size = 0;)
 947   DEBUG_ONLY(mark_bitmap_count = mark_bitmap_size = 0;)
 948 
 949   // Increment the invocation count
 950   heap->increment_total_collections(true);
 951 
 952   // We need to track unique mark sweep invocations as well.
 953   _total_invocations++;
 954 
 955   heap->print_heap_before_gc();
 956   heap->trace_heap_before_gc(&_gc_tracer);
 957 
 958   // Fill in TLABs
 959   heap->accumulate_statistics_all_tlabs();
 960   heap->ensure_parsability(true);  // retire TLABs
 961 
 962   if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
 963     HandleMark hm;  // Discard invalid handles created during verification
 964     Universe::verify("Before GC");
 965   }
 966 
 967   // Verify object start arrays
 968   if (VerifyObjectStartArray &&
 969       VerifyBeforeGC) {
 970     heap->old_gen()->verify_object_start_array();
 971   }
 972 
 973   DEBUG_ONLY(mark_bitmap()->verify_clear();)
 974   DEBUG_ONLY(summary_data().verify_clear();)
 975 
 976   // Have worker threads release resources the next time they run a task.
 977   gc_task_manager()->release_all_resources();
 978 
 979   ParCompactionManager::reset_all_bitmap_query_caches();
 980 }
 981 
 982 void PSParallelCompact::post_compact()
 983 {
 984   GCTraceTime(Trace, gc, phases) tm("Post Compact", &_gc_timer);
 985 
 986   for (unsigned int id = old_space_id; id < last_space_id; ++id) {
 987     // Clear the marking bitmap, summary data and split info.
 988     clear_data_covering_space(SpaceId(id));
 989     // Update top().  Must be done after clearing the bitmap and summary data.
 990     _space_info[id].publish_new_top();
 991   }
 992 
 993   MutableSpace* const eden_space = _space_info[eden_space_id].space();
 994   MutableSpace* const from_space = _space_info[from_space_id].space();
 995   MutableSpace* const to_space   = _space_info[to_space_id].space();
 996 
 997   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
 998   bool eden_empty = eden_space->is_empty();
 999   if (!eden_empty) {
1000     eden_empty = absorb_live_data_from_eden(heap->size_policy(),
1001                                             heap->young_gen(), heap->old_gen());
1002   }
1003 
1004   // Update heap occupancy information which is used as input to the soft ref
1005   // clearing policy at the next gc.
1006   Universe::update_heap_info_at_gc();
1007 
1008   bool young_gen_empty = eden_empty && from_space->is_empty() &&
1009     to_space->is_empty();
1010 
1011   ModRefBarrierSet* modBS = barrier_set_cast<ModRefBarrierSet>(heap->barrier_set());
1012   MemRegion old_mr = heap->old_gen()->reserved();
1013   if (young_gen_empty) {
1014     modBS->clear(MemRegion(old_mr.start(), old_mr.end()));
1015   } else {
1016     modBS->invalidate(MemRegion(old_mr.start(), old_mr.end()));
1017   }
1018 
1019   // Delete metaspaces for unloaded class loaders and clean up loader_data graph
1020   ClassLoaderDataGraph::purge();
1021   MetaspaceAux::verify_metrics();
1022 
1023   CodeCache::gc_epilogue();
1024   JvmtiExport::gc_epilogue();
1025 
1026 #if defined(COMPILER2) || INCLUDE_JVMCI
1027   DerivedPointerTable::update_pointers();
1028 #endif
1029 
1030   ref_processor()->enqueue_discovered_references(NULL);
1031 
1032   if (ZapUnusedHeapArea) {
1033     heap->gen_mangle_unused_area();
1034   }
1035 
1036   // Update time of last GC
1037   reset_millis_since_last_gc();
1038 }
1039 
1040 HeapWord*
1041 PSParallelCompact::compute_dense_prefix_via_density(const SpaceId id,
1042                                                     bool maximum_compaction)
1043 {
1044   const size_t region_size = ParallelCompactData::RegionSize;
1045   const ParallelCompactData& sd = summary_data();
1046 
1047   const MutableSpace* const space = _space_info[id].space();
1048   HeapWord* const top_aligned_up = sd.region_align_up(space->top());
1049   const RegionData* const beg_cp = sd.addr_to_region_ptr(space->bottom());
1050   const RegionData* const end_cp = sd.addr_to_region_ptr(top_aligned_up);
1051 
1052   // Skip full regions at the beginning of the space--they are necessarily part
1053   // of the dense prefix.
1054   size_t full_count = 0;
1055   const RegionData* cp;
1056   for (cp = beg_cp; cp < end_cp && cp->data_size() == region_size; ++cp) {
1057     ++full_count;
1058   }
1059 
1060   assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");
1061   const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;
1062   const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval;
1063   if (maximum_compaction || cp == end_cp || interval_ended) {
1064     _maximum_compaction_gc_num = total_invocations();
1065     return sd.region_to_addr(cp);
1066   }
1067 
1068   HeapWord* const new_top = _space_info[id].new_top();
1069   const size_t space_live = pointer_delta(new_top, space->bottom());
1070   const size_t space_used = space->used_in_words();
1071   const size_t space_capacity = space->capacity_in_words();
1072 
1073   const double cur_density = double(space_live) / space_capacity;
1074   const double deadwood_density =
1075     (1.0 - cur_density) * (1.0 - cur_density) * cur_density * cur_density;
1076   const size_t deadwood_goal = size_t(space_capacity * deadwood_density);
1077 
1078   if (TraceParallelOldGCDensePrefix) {
1079     tty->print_cr("cur_dens=%5.3f dw_dens=%5.3f dw_goal=" SIZE_FORMAT,
1080                   cur_density, deadwood_density, deadwood_goal);
1081     tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " "
1082                   "space_cap=" SIZE_FORMAT,
1083                   space_live, space_used,
1084                   space_capacity);
1085   }
1086 
1087   // XXX - Use binary search?
1088   HeapWord* dense_prefix = sd.region_to_addr(cp);
1089   const RegionData* full_cp = cp;
1090   const RegionData* const top_cp = sd.addr_to_region_ptr(space->top() - 1);
1091   while (cp < end_cp) {
1092     HeapWord* region_destination = cp->destination();
1093     const size_t cur_deadwood = pointer_delta(dense_prefix, region_destination);
1094     if (TraceParallelOldGCDensePrefix && Verbose) {
1095       tty->print_cr("c#=" SIZE_FORMAT_W(4) " dst=" PTR_FORMAT " "
1096                     "dp=" PTR_FORMAT " " "cdw=" SIZE_FORMAT_W(8),
1097                     sd.region(cp), p2i(region_destination),
1098                     p2i(dense_prefix), cur_deadwood);
1099     }
1100 
1101     if (cur_deadwood >= deadwood_goal) {
1102       // Found the region that has the correct amount of deadwood to the left.
1103       // This typically occurs after crossing a fairly sparse set of regions, so
1104       // iterate backwards over those sparse regions, looking for the region
1105       // that has the lowest density of live objects 'to the right.'
1106       size_t space_to_left = sd.region(cp) * region_size;
1107       size_t live_to_left = space_to_left - cur_deadwood;
1108       size_t space_to_right = space_capacity - space_to_left;
1109       size_t live_to_right = space_live - live_to_left;
1110       double density_to_right = double(live_to_right) / space_to_right;
1111       while (cp > full_cp) {
1112         --cp;
1113         const size_t prev_region_live_to_right = live_to_right -
1114           cp->data_size();
1115         const size_t prev_region_space_to_right = space_to_right + region_size;
1116         double prev_region_density_to_right =
1117           double(prev_region_live_to_right) / prev_region_space_to_right;
1118         if (density_to_right <= prev_region_density_to_right) {
1119           return dense_prefix;
1120         }
1121         if (TraceParallelOldGCDensePrefix && Verbose) {
1122           tty->print_cr("backing up from c=" SIZE_FORMAT_W(4) " d2r=%10.8f "
1123                         "pc_d2r=%10.8f", sd.region(cp), density_to_right,
1124                         prev_region_density_to_right);
1125         }
1126         dense_prefix -= region_size;
1127         live_to_right = prev_region_live_to_right;
1128         space_to_right = prev_region_space_to_right;
1129         density_to_right = prev_region_density_to_right;
1130       }
1131       return dense_prefix;
1132     }
1133 
1134     dense_prefix += region_size;
1135     ++cp;
1136   }
1137 
1138   return dense_prefix;
1139 }
1140 
1141 #ifndef PRODUCT
1142 void PSParallelCompact::print_dense_prefix_stats(const char* const algorithm,
1143                                                  const SpaceId id,
1144                                                  const bool maximum_compaction,
1145                                                  HeapWord* const addr)
1146 {
1147   const size_t region_idx = summary_data().addr_to_region_idx(addr);
1148   RegionData* const cp = summary_data().region(region_idx);
1149   const MutableSpace* const space = _space_info[id].space();
1150   HeapWord* const new_top = _space_info[id].new_top();
1151 
1152   const size_t space_live = pointer_delta(new_top, space->bottom());
1153   const size_t dead_to_left = pointer_delta(addr, cp->destination());
1154   const size_t space_cap = space->capacity_in_words();
1155   const double dead_to_left_pct = double(dead_to_left) / space_cap;
1156   const size_t live_to_right = new_top - cp->destination();
1157   const size_t dead_to_right = space->top() - addr - live_to_right;
1158 
1159   tty->print_cr("%s=" PTR_FORMAT " dpc=" SIZE_FORMAT_W(5) " "
1160                 "spl=" SIZE_FORMAT " "
1161                 "d2l=" SIZE_FORMAT " d2l%%=%6.4f "
1162                 "d2r=" SIZE_FORMAT " l2r=" SIZE_FORMAT
1163                 " ratio=%10.8f",
1164                 algorithm, p2i(addr), region_idx,
1165                 space_live,
1166                 dead_to_left, dead_to_left_pct,
1167                 dead_to_right, live_to_right,
1168                 double(dead_to_right) / live_to_right);
1169 }
1170 #endif  // #ifndef PRODUCT
1171 
1172 // Return a fraction indicating how much of the generation can be treated as
1173 // "dead wood" (i.e., not reclaimed).  The function uses a normal distribution
1174 // based on the density of live objects in the generation to determine a limit,
1175 // which is then adjusted so the return value is min_percent when the density is
1176 // 1.
1177 //
1178 // The following table shows some return values for a different values of the
1179 // standard deviation (ParallelOldDeadWoodLimiterStdDev); the mean is 0.5 and
1180 // min_percent is 1.
1181 //
1182 //                          fraction allowed as dead wood
1183 //         -----------------------------------------------------------------
1184 // density std_dev=70 std_dev=75 std_dev=80 std_dev=85 std_dev=90 std_dev=95
1185 // ------- ---------- ---------- ---------- ---------- ---------- ----------
1186 // 0.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
1187 // 0.05000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
1188 // 0.10000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
1189 // 0.15000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
1190 // 0.20000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
1191 // 0.25000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
1192 // 0.30000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
1193 // 0.35000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
1194 // 0.40000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
1195 // 0.45000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
1196 // 0.50000 0.13832410 0.11599237 0.09847664 0.08456518 0.07338887 0.06431510
1197 // 0.55000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
1198 // 0.60000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
1199 // 0.65000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
1200 // 0.70000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
1201 // 0.75000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
1202 // 0.80000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
1203 // 0.85000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
1204 // 0.90000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
1205 // 0.95000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
1206 // 1.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
1207 
1208 double PSParallelCompact::dead_wood_limiter(double density, size_t min_percent)
1209 {
1210   assert(_dwl_initialized, "uninitialized");
1211 
1212   // The raw limit is the value of the normal distribution at x = density.
1213   const double raw_limit = normal_distribution(density);
1214 
1215   // Adjust the raw limit so it becomes the minimum when the density is 1.
1216   //
1217   // First subtract the adjustment value (which is simply the precomputed value
1218   // normal_distribution(1.0)); this yields a value of 0 when the density is 1.
1219   // Then add the minimum value, so the minimum is returned when the density is
1220   // 1.  Finally, prevent negative values, which occur when the mean is not 0.5.
1221   const double min = double(min_percent) / 100.0;
1222   const double limit = raw_limit - _dwl_adjustment + min;
1223   return MAX2(limit, 0.0);
1224 }
1225 
1226 ParallelCompactData::RegionData*
1227 PSParallelCompact::first_dead_space_region(const RegionData* beg,
1228                                            const RegionData* end)
1229 {
1230   const size_t region_size = ParallelCompactData::RegionSize;
1231   ParallelCompactData& sd = summary_data();
1232   size_t left = sd.region(beg);
1233   size_t right = end > beg ? sd.region(end) - 1 : left;
1234 
1235   // Binary search.
1236   while (left < right) {
1237     // Equivalent to (left + right) / 2, but does not overflow.
1238     const size_t middle = left + (right - left) / 2;
1239     RegionData* const middle_ptr = sd.region(middle);
1240     HeapWord* const dest = middle_ptr->destination();
1241     HeapWord* const addr = sd.region_to_addr(middle);
1242     assert(dest != NULL, "sanity");
1243     assert(dest <= addr, "must move left");
1244 
1245     if (middle > left && dest < addr) {
1246       right = middle - 1;
1247     } else if (middle < right && middle_ptr->data_size() == region_size) {
1248       left = middle + 1;
1249     } else {
1250       return middle_ptr;
1251     }
1252   }
1253   return sd.region(left);
1254 }
1255 
1256 ParallelCompactData::RegionData*
1257 PSParallelCompact::dead_wood_limit_region(const RegionData* beg,
1258                                           const RegionData* end,
1259                                           size_t dead_words)
1260 {
1261   ParallelCompactData& sd = summary_data();
1262   size_t left = sd.region(beg);
1263   size_t right = end > beg ? sd.region(end) - 1 : left;
1264 
1265   // Binary search.
1266   while (left < right) {
1267     // Equivalent to (left + right) / 2, but does not overflow.
1268     const size_t middle = left + (right - left) / 2;
1269     RegionData* const middle_ptr = sd.region(middle);
1270     HeapWord* const dest = middle_ptr->destination();
1271     HeapWord* const addr = sd.region_to_addr(middle);
1272     assert(dest != NULL, "sanity");
1273     assert(dest <= addr, "must move left");
1274 
1275     const size_t dead_to_left = pointer_delta(addr, dest);
1276     if (middle > left && dead_to_left > dead_words) {
1277       right = middle - 1;
1278     } else if (middle < right && dead_to_left < dead_words) {
1279       left = middle + 1;
1280     } else {
1281       return middle_ptr;
1282     }
1283   }
1284   return sd.region(left);
1285 }
1286 
1287 // The result is valid during the summary phase, after the initial summarization
1288 // of each space into itself, and before final summarization.
1289 inline double
1290 PSParallelCompact::reclaimed_ratio(const RegionData* const cp,
1291                                    HeapWord* const bottom,
1292                                    HeapWord* const top,
1293                                    HeapWord* const new_top)
1294 {
1295   ParallelCompactData& sd = summary_data();
1296 
1297   assert(cp != NULL, "sanity");
1298   assert(bottom != NULL, "sanity");
1299   assert(top != NULL, "sanity");
1300   assert(new_top != NULL, "sanity");
1301   assert(top >= new_top, "summary data problem?");
1302   assert(new_top > bottom, "space is empty; should not be here");
1303   assert(new_top >= cp->destination(), "sanity");
1304   assert(top >= sd.region_to_addr(cp), "sanity");
1305 
1306   HeapWord* const destination = cp->destination();
1307   const size_t dense_prefix_live  = pointer_delta(destination, bottom);
1308   const size_t compacted_region_live = pointer_delta(new_top, destination);
1309   const size_t compacted_region_used = pointer_delta(top,
1310                                                      sd.region_to_addr(cp));
1311   const size_t reclaimable = compacted_region_used - compacted_region_live;
1312 
1313   const double divisor = dense_prefix_live + 1.25 * compacted_region_live;
1314   return double(reclaimable) / divisor;
1315 }
1316 
1317 // Return the address of the end of the dense prefix, a.k.a. the start of the
1318 // compacted region.  The address is always on a region boundary.
1319 //
1320 // Completely full regions at the left are skipped, since no compaction can
1321 // occur in those regions.  Then the maximum amount of dead wood to allow is
1322 // computed, based on the density (amount live / capacity) of the generation;
1323 // the region with approximately that amount of dead space to the left is
1324 // identified as the limit region.  Regions between the last completely full
1325 // region and the limit region are scanned and the one that has the best
1326 // (maximum) reclaimed_ratio() is selected.
1327 HeapWord*
1328 PSParallelCompact::compute_dense_prefix(const SpaceId id,
1329                                         bool maximum_compaction)
1330 {
1331   const size_t region_size = ParallelCompactData::RegionSize;
1332   const ParallelCompactData& sd = summary_data();
1333 
1334   const MutableSpace* const space = _space_info[id].space();
1335   HeapWord* const top = space->top();
1336   HeapWord* const top_aligned_up = sd.region_align_up(top);
1337   HeapWord* const new_top = _space_info[id].new_top();
1338   HeapWord* const new_top_aligned_up = sd.region_align_up(new_top);
1339   HeapWord* const bottom = space->bottom();
1340   const RegionData* const beg_cp = sd.addr_to_region_ptr(bottom);
1341   const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
1342   const RegionData* const new_top_cp =
1343     sd.addr_to_region_ptr(new_top_aligned_up);
1344 
1345   // Skip full regions at the beginning of the space--they are necessarily part
1346   // of the dense prefix.
1347   const RegionData* const full_cp = first_dead_space_region(beg_cp, new_top_cp);
1348   assert(full_cp->destination() == sd.region_to_addr(full_cp) ||
1349          space->is_empty(), "no dead space allowed to the left");
1350   assert(full_cp->data_size() < region_size || full_cp == new_top_cp - 1,
1351          "region must have dead space");
1352 
1353   // The gc number is saved whenever a maximum compaction is done, and used to
1354   // determine when the maximum compaction interval has expired.  This avoids
1355   // successive max compactions for different reasons.
1356   assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");
1357   const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;
1358   const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval ||
1359     total_invocations() == HeapFirstMaximumCompactionCount;
1360   if (maximum_compaction || full_cp == top_cp || interval_ended) {
1361     _maximum_compaction_gc_num = total_invocations();
1362     return sd.region_to_addr(full_cp);
1363   }
1364 
1365   const size_t space_live = pointer_delta(new_top, bottom);
1366   const size_t space_used = space->used_in_words();
1367   const size_t space_capacity = space->capacity_in_words();
1368 
1369   const double density = double(space_live) / double(space_capacity);
1370   const size_t min_percent_free = MarkSweepDeadRatio;
1371   const double limiter = dead_wood_limiter(density, min_percent_free);
1372   const size_t dead_wood_max = space_used - space_live;
1373   const size_t dead_wood_limit = MIN2(size_t(space_capacity * limiter),
1374                                       dead_wood_max);
1375 
1376   if (TraceParallelOldGCDensePrefix) {
1377     tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " "
1378                   "space_cap=" SIZE_FORMAT,
1379                   space_live, space_used,
1380                   space_capacity);
1381     tty->print_cr("dead_wood_limiter(%6.4f, " SIZE_FORMAT ")=%6.4f "
1382                   "dead_wood_max=" SIZE_FORMAT " dead_wood_limit=" SIZE_FORMAT,
1383                   density, min_percent_free, limiter,
1384                   dead_wood_max, dead_wood_limit);
1385   }
1386 
1387   // Locate the region with the desired amount of dead space to the left.
1388   const RegionData* const limit_cp =
1389     dead_wood_limit_region(full_cp, top_cp, dead_wood_limit);
1390 
1391   // Scan from the first region with dead space to the limit region and find the
1392   // one with the best (largest) reclaimed ratio.
1393   double best_ratio = 0.0;
1394   const RegionData* best_cp = full_cp;
1395   for (const RegionData* cp = full_cp; cp < limit_cp; ++cp) {
1396     double tmp_ratio = reclaimed_ratio(cp, bottom, top, new_top);
1397     if (tmp_ratio > best_ratio) {
1398       best_cp = cp;
1399       best_ratio = tmp_ratio;
1400     }
1401   }
1402 
1403   return sd.region_to_addr(best_cp);
1404 }
1405 
1406 void PSParallelCompact::summarize_spaces_quick()
1407 {
1408   for (unsigned int i = 0; i < last_space_id; ++i) {
1409     const MutableSpace* space = _space_info[i].space();
1410     HeapWord** nta = _space_info[i].new_top_addr();
1411     bool result = _summary_data.summarize(_space_info[i].split_info(),
1412                                           space->bottom(), space->top(), NULL,
1413                                           space->bottom(), space->end(), nta);
1414     assert(result, "space must fit into itself");
1415     _space_info[i].set_dense_prefix(space->bottom());
1416   }
1417 }
1418 
1419 void PSParallelCompact::fill_dense_prefix_end(SpaceId id)
1420 {
1421   HeapWord* const dense_prefix_end = dense_prefix(id);
1422   const RegionData* region = _summary_data.addr_to_region_ptr(dense_prefix_end);
1423   const idx_t dense_prefix_bit = _mark_bitmap.addr_to_bit(dense_prefix_end);
1424   if (dead_space_crosses_boundary(region, dense_prefix_bit)) {
1425     // Only enough dead space is filled so that any remaining dead space to the
1426     // left is larger than the minimum filler object.  (The remainder is filled
1427     // during the copy/update phase.)
1428     //
1429     // The size of the dead space to the right of the boundary is not a
1430     // concern, since compaction will be able to use whatever space is
1431     // available.
1432     //
1433     // Here '||' is the boundary, 'x' represents a don't care bit and a box
1434     // surrounds the space to be filled with an object.
1435     //
1436     // In the 32-bit VM, each bit represents two 32-bit words:
1437     //                              +---+
1438     // a) beg_bits:  ...  x   x   x | 0 | ||   0   x  x  ...
1439     //    end_bits:  ...  x   x   x | 0 | ||   0   x  x  ...
1440     //                              +---+
1441     //
1442     // In the 64-bit VM, each bit represents one 64-bit word:
1443     //                              +------------+
1444     // b) beg_bits:  ...  x   x   x | 0   ||   0 | x  x  ...
1445     //    end_bits:  ...  x   x   1 | 0   ||   0 | x  x  ...
1446     //                              +------------+
1447     //                          +-------+
1448     // c) beg_bits:  ...  x   x | 0   0 | ||   0   x  x  ...
1449     //    end_bits:  ...  x   1 | 0   0 | ||   0   x  x  ...
1450     //                          +-------+
1451     //                      +-----------+
1452     // d) beg_bits:  ...  x | 0   0   0 | ||   0   x  x  ...
1453     //    end_bits:  ...  1 | 0   0   0 | ||   0   x  x  ...
1454     //                      +-----------+
1455     //                          +-------+
1456     // e) beg_bits:  ...  0   0 | 0   0 | ||   0   x  x  ...
1457     //    end_bits:  ...  0   0 | 0   0 | ||   0   x  x  ...
1458     //                          +-------+
1459 
1460     // Initially assume case a, c or e will apply.
1461     size_t obj_len = CollectedHeap::min_fill_size();
1462     HeapWord* obj_beg = dense_prefix_end - obj_len;
1463 
1464 #ifdef  _LP64
1465     if (MinObjAlignment > 1) { // object alignment > heap word size
1466       // Cases a, c or e.
1467     } else if (_mark_bitmap.is_obj_end(dense_prefix_bit - 2)) {
1468       // Case b above.
1469       obj_beg = dense_prefix_end - 1;
1470     } else if (!_mark_bitmap.is_obj_end(dense_prefix_bit - 3) &&
1471                _mark_bitmap.is_obj_end(dense_prefix_bit - 4)) {
1472       // Case d above.
1473       obj_beg = dense_prefix_end - 3;
1474       obj_len = 3;
1475     }
1476 #endif  // #ifdef _LP64
1477 
1478     CollectedHeap::fill_with_object(obj_beg, obj_len);
1479     _mark_bitmap.mark_obj(obj_beg, obj_len);
1480     _summary_data.add_obj(obj_beg, obj_len);
1481     assert(start_array(id) != NULL, "sanity");
1482     start_array(id)->allocate_block(obj_beg);
1483   }
1484 }
1485 
1486 void











1487 PSParallelCompact::summarize_space(SpaceId id, bool maximum_compaction)
1488 {
1489   assert(id < last_space_id, "id out of range");
1490   assert(_space_info[id].dense_prefix() == _space_info[id].space()->bottom(),
1491          "should have been reset in summarize_spaces_quick()");
1492 
1493   const MutableSpace* space = _space_info[id].space();
1494   if (_space_info[id].new_top() != space->bottom()) {
1495     HeapWord* dense_prefix_end = compute_dense_prefix(id, maximum_compaction);
1496     _space_info[id].set_dense_prefix(dense_prefix_end);
1497 
1498 #ifndef PRODUCT
1499     if (TraceParallelOldGCDensePrefix) {
1500       print_dense_prefix_stats("ratio", id, maximum_compaction,
1501                                dense_prefix_end);
1502       HeapWord* addr = compute_dense_prefix_via_density(id, maximum_compaction);
1503       print_dense_prefix_stats("density", id, maximum_compaction, addr);
1504     }
1505 #endif  // #ifndef PRODUCT
1506 
1507     // Recompute the summary data, taking into account the dense prefix.  If
1508     // every last byte will be reclaimed, then the existing summary data which
1509     // compacts everything can be left in place.
1510     if (!maximum_compaction && dense_prefix_end != space->bottom()) {
1511       // If dead space crosses the dense prefix boundary, it is (at least
1512       // partially) filled with a dummy object, marked live and added to the
1513       // summary data.  This simplifies the copy/update phase and must be done
1514       // before the final locations of objects are determined, to prevent
1515       // leaving a fragment of dead space that is too small to fill.
1516       fill_dense_prefix_end(id);
1517 
1518       // Compute the destination of each Region, and thus each object.
1519       _summary_data.summarize_dense_prefix(space->bottom(), dense_prefix_end);
1520       _summary_data.summarize(_space_info[id].split_info(),
1521                               dense_prefix_end, space->top(), NULL,
1522                               dense_prefix_end, space->end(),
1523                               _space_info[id].new_top_addr());
1524     }
1525   }
1526 
1527   if (log_develop_is_enabled(Trace, gc, compaction, phases)) {
1528     const size_t region_size = ParallelCompactData::RegionSize;
1529     HeapWord* const dense_prefix_end = _space_info[id].dense_prefix();
1530     const size_t dp_region = _summary_data.addr_to_region_idx(dense_prefix_end);
1531     const size_t dp_words = pointer_delta(dense_prefix_end, space->bottom());
1532     HeapWord* const new_top = _space_info[id].new_top();
1533     const HeapWord* nt_aligned_up = _summary_data.region_align_up(new_top);
1534     const size_t cr_words = pointer_delta(nt_aligned_up, dense_prefix_end);
1535     log_develop_trace(gc, compaction, phases)(
1536         "id=%d cap=" SIZE_FORMAT " dp=" PTR_FORMAT " "
1537         "dp_region=" SIZE_FORMAT " " "dp_count=" SIZE_FORMAT " "
1538         "cr_count=" SIZE_FORMAT " " "nt=" PTR_FORMAT,
1539         id, space->capacity_in_words(), p2i(dense_prefix_end),
1540         dp_region, dp_words / region_size,
1541         cr_words / region_size, p2i(new_top));
1542   }
1543 }
1544 
1545 #ifndef PRODUCT
1546 void PSParallelCompact::summary_phase_msg(SpaceId dst_space_id,
1547                                           HeapWord* dst_beg, HeapWord* dst_end,
1548                                           SpaceId src_space_id,
1549                                           HeapWord* src_beg, HeapWord* src_end)
1550 {
1551   log_develop_trace(gc, compaction, phases)(
1552       "Summarizing %d [%s] into %d [%s]:  "
1553       "src=" PTR_FORMAT "-" PTR_FORMAT " "
1554       SIZE_FORMAT "-" SIZE_FORMAT " "
1555       "dst=" PTR_FORMAT "-" PTR_FORMAT " "
1556       SIZE_FORMAT "-" SIZE_FORMAT,
1557       src_space_id, space_names[src_space_id],
1558       dst_space_id, space_names[dst_space_id],
1559       p2i(src_beg), p2i(src_end),
1560       _summary_data.addr_to_region_idx(src_beg),
1561       _summary_data.addr_to_region_idx(src_end),
1562       p2i(dst_beg), p2i(dst_end),
1563       _summary_data.addr_to_region_idx(dst_beg),
1564       _summary_data.addr_to_region_idx(dst_end));
1565 }
1566 #endif  // #ifndef PRODUCT
1567 
1568 void PSParallelCompact::summary_phase(ParCompactionManager* cm,
1569                                       bool maximum_compaction)
1570 {
1571   GCTraceTime(Trace, gc, phases) tm("Summary Phase", &_gc_timer);
1572 
1573 #ifdef  ASSERT
1574   if (TraceParallelOldGCMarkingPhase) {
1575     tty->print_cr("add_obj_count=" SIZE_FORMAT " "
1576                   "add_obj_bytes=" SIZE_FORMAT,
1577                   add_obj_count, add_obj_size * HeapWordSize);
1578     tty->print_cr("mark_bitmap_count=" SIZE_FORMAT " "
1579                   "mark_bitmap_bytes=" SIZE_FORMAT,
1580                   mark_bitmap_count, mark_bitmap_size * HeapWordSize);
1581   }
1582 #endif  // #ifdef ASSERT
1583 
1584   // Quick summarization of each space into itself, to see how much is live.
1585   summarize_spaces_quick();
1586 
1587   log_develop_trace(gc, compaction, phases)("summary phase:  after summarizing each space to self");
1588   NOT_PRODUCT(print_region_ranges());
1589   NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info));
1590 
1591   // The amount of live data that will end up in old space (assuming it fits).
1592   size_t old_space_total_live = 0;
1593   for (unsigned int id = old_space_id; id < last_space_id; ++id) {
1594     old_space_total_live += pointer_delta(_space_info[id].new_top(),
1595                                           _space_info[id].space()->bottom());
1596   }
1597 
1598   MutableSpace* const old_space = _space_info[old_space_id].space();
1599   const size_t old_capacity = old_space->capacity_in_words();
1600   if (old_space_total_live > old_capacity) {
1601     // XXX - should also try to expand
1602     maximum_compaction = true;
1603   }
1604 
1605   // Old generations.
1606   summarize_space(old_space_id, maximum_compaction);
1607 
1608   // Summarize the remaining spaces in the young gen.  The initial target space
1609   // is the old gen.  If a space does not fit entirely into the target, then the
1610   // remainder is compacted into the space itself and that space becomes the new
1611   // target.
1612   SpaceId dst_space_id = old_space_id;
1613   HeapWord* dst_space_end = old_space->end();
1614   HeapWord** new_top_addr = _space_info[dst_space_id].new_top_addr();
1615   for (unsigned int id = eden_space_id; id < last_space_id; ++id) {
1616     const MutableSpace* space = _space_info[id].space();
1617     const size_t live = pointer_delta(_space_info[id].new_top(),
1618                                       space->bottom());
1619     const size_t available = pointer_delta(dst_space_end, *new_top_addr);
1620 
1621     NOT_PRODUCT(summary_phase_msg(dst_space_id, *new_top_addr, dst_space_end,
1622                                   SpaceId(id), space->bottom(), space->top());)
1623     if (live > 0 && live <= available) {
1624       // All the live data will fit.
1625       bool done = _summary_data.summarize(_space_info[id].split_info(),
1626                                           space->bottom(), space->top(),
1627                                           NULL,
1628                                           *new_top_addr, dst_space_end,
1629                                           new_top_addr);
1630       assert(done, "space must fit into old gen");
1631 
1632       // Reset the new_top value for the space.
1633       _space_info[id].set_new_top(space->bottom());
1634     } else if (live > 0) {
1635       // Attempt to fit part of the source space into the target space.
1636       HeapWord* next_src_addr = NULL;
1637       bool done = _summary_data.summarize(_space_info[id].split_info(),
1638                                           space->bottom(), space->top(),
1639                                           &next_src_addr,
1640                                           *new_top_addr, dst_space_end,
1641                                           new_top_addr);
1642       assert(!done, "space should not fit into old gen");
1643       assert(next_src_addr != NULL, "sanity");
1644 
1645       // The source space becomes the new target, so the remainder is compacted
1646       // within the space itself.
1647       dst_space_id = SpaceId(id);
1648       dst_space_end = space->end();
1649       new_top_addr = _space_info[id].new_top_addr();
1650       NOT_PRODUCT(summary_phase_msg(dst_space_id,
1651                                     space->bottom(), dst_space_end,
1652                                     SpaceId(id), next_src_addr, space->top());)
1653       done = _summary_data.summarize(_space_info[id].split_info(),
1654                                      next_src_addr, space->top(),
1655                                      NULL,
1656                                      space->bottom(), dst_space_end,
1657                                      new_top_addr);
1658       assert(done, "space must fit when compacted into itself");
1659       assert(*new_top_addr <= space->top(), "usage should not grow");
1660     }
1661   }
1662 
1663   log_develop_trace(gc, compaction, phases)("Summary_phase:  after final summarization");
1664   NOT_PRODUCT(print_region_ranges());
1665   NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info));
1666 }
1667 
1668 // This method should contain all heap-specific policy for invoking a full
1669 // collection.  invoke_no_policy() will only attempt to compact the heap; it
1670 // will do nothing further.  If we need to bail out for policy reasons, scavenge
1671 // before full gc, or any other specialized behavior, it needs to be added here.
1672 //
1673 // Note that this method should only be called from the vm_thread while at a
1674 // safepoint.
1675 //
1676 // Note that the all_soft_refs_clear flag in the collector policy
1677 // may be true because this method can be called without intervening
1678 // activity.  For example when the heap space is tight and full measure
1679 // are being taken to free space.
1680 void PSParallelCompact::invoke(bool maximum_heap_compaction) {
1681   assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
1682   assert(Thread::current() == (Thread*)VMThread::vm_thread(),
1683          "should be in vm thread");
1684 
1685   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
1686   GCCause::Cause gc_cause = heap->gc_cause();
1687   assert(!heap->is_gc_active(), "not reentrant");
1688 
1689   PSAdaptiveSizePolicy* policy = heap->size_policy();
1690   IsGCActiveMark mark;
1691 
1692   if (ScavengeBeforeFullGC) {
1693     PSScavenge::invoke_no_policy();
1694   }
1695 
1696   const bool clear_all_soft_refs =
1697     heap->collector_policy()->should_clear_all_soft_refs();
1698 
1699   PSParallelCompact::invoke_no_policy(clear_all_soft_refs ||
1700                                       maximum_heap_compaction);
1701 }
1702 
1703 // This method contains no policy. You should probably
1704 // be calling invoke() instead.
1705 bool PSParallelCompact::invoke_no_policy(bool maximum_heap_compaction) {
1706   assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
1707   assert(ref_processor() != NULL, "Sanity");
1708 
1709   if (GCLocker::check_active_before_gc()) {
1710     return false;
1711   }
1712 
1713   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
1714 
1715   GCIdMark gc_id_mark;
1716   _gc_timer.register_gc_start();
1717   _gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start());
1718 
1719   TimeStamp marking_start;
1720   TimeStamp compaction_start;
1721   TimeStamp collection_exit;
1722 
1723   GCCause::Cause gc_cause = heap->gc_cause();
1724   PSYoungGen* young_gen = heap->young_gen();
1725   PSOldGen* old_gen = heap->old_gen();
1726   PSAdaptiveSizePolicy* size_policy = heap->size_policy();
1727 
1728   // The scope of casr should end after code that can change
1729   // CollectorPolicy::_should_clear_all_soft_refs.
1730   ClearedAllSoftRefs casr(maximum_heap_compaction,
1731                           heap->collector_policy());
1732 
1733   if (ZapUnusedHeapArea) {
1734     // Save information needed to minimize mangling
1735     heap->record_gen_tops_before_GC();
1736   }
1737 
1738   // Make sure data structures are sane, make the heap parsable, and do other
1739   // miscellaneous bookkeeping.
1740   pre_compact();
1741 
1742   PreGCValues pre_gc_values(heap);
1743 
1744   // Get the compaction manager reserved for the VM thread.
1745   ParCompactionManager* const vmthread_cm =
1746     ParCompactionManager::manager_array(gc_task_manager()->workers());
1747 
1748   {
1749     ResourceMark rm;
1750     HandleMark hm;
1751 
1752     // Set the number of GC threads to be used in this collection
1753     gc_task_manager()->set_active_gang();
1754     gc_task_manager()->task_idle_workers();
1755 
1756     GCTraceCPUTime tcpu;
1757     GCTraceTime(Info, gc) tm("Pause Full", NULL, gc_cause, true);
1758 
1759     heap->pre_full_gc_dump(&_gc_timer);
1760 
1761     TraceCollectorStats tcs(counters());
1762     TraceMemoryManagerStats tms(true /* Full GC */,gc_cause);
1763 
1764     if (TraceOldGenTime) accumulated_time()->start();
1765 
1766     // Let the size policy know we're starting
1767     size_policy->major_collection_begin();
1768 
1769     CodeCache::gc_prologue();
1770 
1771 #if defined(COMPILER2) || INCLUDE_JVMCI
1772     DerivedPointerTable::clear();
1773 #endif
1774 
1775     ref_processor()->enable_discovery();
1776     ref_processor()->setup_policy(maximum_heap_compaction);
1777 
1778     bool marked_for_unloading = false;
1779 
1780     marking_start.update();
1781     marking_phase(vmthread_cm, maximum_heap_compaction, &_gc_tracer);
1782 
1783     bool max_on_system_gc = UseMaximumCompactionOnSystemGC
1784       && GCCause::is_user_requested_gc(gc_cause);
1785     summary_phase(vmthread_cm, maximum_heap_compaction || max_on_system_gc);
1786 
1787 #if defined(COMPILER2) || INCLUDE_JVMCI
1788     assert(DerivedPointerTable::is_active(), "Sanity");
1789     DerivedPointerTable::set_active(false);
1790 #endif
1791 
1792     // adjust_roots() updates Universe::_intArrayKlassObj which is
1793     // needed by the compaction for filling holes in the dense prefix.
1794     adjust_roots(vmthread_cm);
1795 
1796     compaction_start.update();
1797     compact();
1798 
1799     // Reset the mark bitmap, summary data, and do other bookkeeping.  Must be
1800     // done before resizing.
1801     post_compact();
1802 
1803     // Let the size policy know we're done
1804     size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause);
1805 
1806     if (UseAdaptiveSizePolicy) {
1807       log_debug(gc, ergo)("AdaptiveSizeStart: collection: %d ", heap->total_collections());
1808       log_trace(gc, ergo)("old_gen_capacity: " SIZE_FORMAT " young_gen_capacity: " SIZE_FORMAT,
1809                           old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes());
1810 
1811       // Don't check if the size_policy is ready here.  Let
1812       // the size_policy check that internally.
1813       if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&
1814           AdaptiveSizePolicy::should_update_promo_stats(gc_cause)) {
1815         // Swap the survivor spaces if from_space is empty. The
1816         // resize_young_gen() called below is normally used after
1817         // a successful young GC and swapping of survivor spaces;
1818         // otherwise, it will fail to resize the young gen with
1819         // the current implementation.
1820         if (young_gen->from_space()->is_empty()) {
1821           young_gen->from_space()->clear(SpaceDecorator::Mangle);
1822           young_gen->swap_spaces();
1823         }
1824 
1825         // Calculate optimal free space amounts
1826         assert(young_gen->max_size() >
1827           young_gen->from_space()->capacity_in_bytes() +
1828           young_gen->to_space()->capacity_in_bytes(),
1829           "Sizes of space in young gen are out-of-bounds");
1830 
1831         size_t young_live = young_gen->used_in_bytes();
1832         size_t eden_live = young_gen->eden_space()->used_in_bytes();
1833         size_t old_live = old_gen->used_in_bytes();
1834         size_t cur_eden = young_gen->eden_space()->capacity_in_bytes();
1835         size_t max_old_gen_size = old_gen->max_gen_size();
1836         size_t max_eden_size = young_gen->max_size() -
1837           young_gen->from_space()->capacity_in_bytes() -
1838           young_gen->to_space()->capacity_in_bytes();
1839 
1840         // Used for diagnostics
1841         size_policy->clear_generation_free_space_flags();
1842 
1843         size_policy->compute_generations_free_space(young_live,
1844                                                     eden_live,
1845                                                     old_live,
1846                                                     cur_eden,
1847                                                     max_old_gen_size,
1848                                                     max_eden_size,
1849                                                     true /* full gc*/);
1850 
1851         size_policy->check_gc_overhead_limit(young_live,
1852                                              eden_live,
1853                                              max_old_gen_size,
1854                                              max_eden_size,
1855                                              true /* full gc*/,
1856                                              gc_cause,
1857                                              heap->collector_policy());
1858 
1859         size_policy->decay_supplemental_growth(true /* full gc*/);
1860 
1861         heap->resize_old_gen(
1862           size_policy->calculated_old_free_size_in_bytes());
1863 
1864         heap->resize_young_gen(size_policy->calculated_eden_size_in_bytes(),
1865                                size_policy->calculated_survivor_size_in_bytes());
1866       }
1867 
1868       log_debug(gc, ergo)("AdaptiveSizeStop: collection: %d ", heap->total_collections());
1869     }
1870 
1871     if (UsePerfData) {
1872       PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters();
1873       counters->update_counters();
1874       counters->update_old_capacity(old_gen->capacity_in_bytes());
1875       counters->update_young_capacity(young_gen->capacity_in_bytes());
1876     }
1877 
1878     heap->resize_all_tlabs();
1879 
1880     // Resize the metaspace capacity after a collection
1881     MetaspaceGC::compute_new_size();
1882 
1883     if (TraceOldGenTime) {
1884       accumulated_time()->stop();
1885     }
1886 
1887     young_gen->print_used_change(pre_gc_values.young_gen_used());
1888     old_gen->print_used_change(pre_gc_values.old_gen_used());
1889     MetaspaceAux::print_metaspace_change(pre_gc_values.metadata_used());
1890 
1891     // Track memory usage and detect low memory
1892     MemoryService::track_memory_usage();
1893     heap->update_counters();
1894     gc_task_manager()->release_idle_workers();
1895 
1896     heap->post_full_gc_dump(&_gc_timer);
1897   }
1898 
1899 #ifdef ASSERT
1900   for (size_t i = 0; i < ParallelGCThreads + 1; ++i) {
1901     ParCompactionManager* const cm =
1902       ParCompactionManager::manager_array(int(i));
1903     assert(cm->marking_stack()->is_empty(),       "should be empty");
1904     assert(ParCompactionManager::region_list(int(i))->is_empty(), "should be empty");
1905   }
1906 #endif // ASSERT
1907 
1908   if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
1909     HandleMark hm;  // Discard invalid handles created during verification
1910     Universe::verify("After GC");
1911   }
1912 
1913   // Re-verify object start arrays
1914   if (VerifyObjectStartArray &&
1915       VerifyAfterGC) {
1916     old_gen->verify_object_start_array();
1917   }
1918 
1919   if (ZapUnusedHeapArea) {
1920     old_gen->object_space()->check_mangled_unused_area_complete();
1921   }
1922 
1923   NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
1924 
1925   collection_exit.update();
1926 
1927   heap->print_heap_after_gc();
1928   heap->trace_heap_after_gc(&_gc_tracer);
1929 
1930   log_debug(gc, task, time)("VM-Thread " JLONG_FORMAT " " JLONG_FORMAT " " JLONG_FORMAT,
1931                          marking_start.ticks(), compaction_start.ticks(),
1932                          collection_exit.ticks());
1933   gc_task_manager()->print_task_time_stamps();
1934 
1935 #ifdef TRACESPINNING
1936   ParallelTaskTerminator::print_termination_counts();
1937 #endif
1938 
1939   AdaptiveSizePolicyOutput::print(size_policy, heap->total_collections());
1940 
1941   _gc_timer.register_gc_end();
1942 
1943   _gc_tracer.report_dense_prefix(dense_prefix(old_space_id));
1944   _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions());
1945 
1946   return true;
1947 }
1948 
1949 bool PSParallelCompact::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
1950                                              PSYoungGen* young_gen,
1951                                              PSOldGen* old_gen) {
1952   MutableSpace* const eden_space = young_gen->eden_space();
1953   assert(!eden_space->is_empty(), "eden must be non-empty");
1954   assert(young_gen->virtual_space()->alignment() ==
1955          old_gen->virtual_space()->alignment(), "alignments do not match");
1956 
1957   if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) {
1958     return false;
1959   }
1960 
1961   // Both generations must be completely committed.
1962   if (young_gen->virtual_space()->uncommitted_size() != 0) {
1963     return false;
1964   }
1965   if (old_gen->virtual_space()->uncommitted_size() != 0) {
1966     return false;
1967   }
1968 
1969   // Figure out how much to take from eden.  Include the average amount promoted
1970   // in the total; otherwise the next young gen GC will simply bail out to a
1971   // full GC.
1972   const size_t alignment = old_gen->virtual_space()->alignment();
1973   const size_t eden_used = eden_space->used_in_bytes();
1974   const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average();
1975   const size_t absorb_size = align_size_up(eden_used + promoted, alignment);
1976   const size_t eden_capacity = eden_space->capacity_in_bytes();
1977 
1978   if (absorb_size >= eden_capacity) {
1979     return false; // Must leave some space in eden.
1980   }
1981 
1982   const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size;
1983   if (new_young_size < young_gen->min_gen_size()) {
1984     return false; // Respect young gen minimum size.
1985   }
1986 
1987   log_trace(heap, ergo)(" absorbing " SIZE_FORMAT "K:  "
1988                         "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K "
1989                         "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K "
1990                         "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ",
1991                         absorb_size / K,
1992                         eden_capacity / K, (eden_capacity - absorb_size) / K,
1993                         young_gen->from_space()->used_in_bytes() / K,
1994                         young_gen->to_space()->used_in_bytes() / K,
1995                         young_gen->capacity_in_bytes() / K, new_young_size / K);
1996 
1997   // Fill the unused part of the old gen.
1998   MutableSpace* const old_space = old_gen->object_space();
1999   HeapWord* const unused_start = old_space->top();
2000   size_t const unused_words = pointer_delta(old_space->end(), unused_start);
2001 
2002   if (unused_words > 0) {
2003     if (unused_words < CollectedHeap::min_fill_size()) {
2004       return false;  // If the old gen cannot be filled, must give up.
2005     }
2006     CollectedHeap::fill_with_objects(unused_start, unused_words);
2007   }
2008 
2009   // Take the live data from eden and set both top and end in the old gen to
2010   // eden top.  (Need to set end because reset_after_change() mangles the region
2011   // from end to virtual_space->high() in debug builds).
2012   HeapWord* const new_top = eden_space->top();
2013   old_gen->virtual_space()->expand_into(young_gen->virtual_space(),
2014                                         absorb_size);
2015   young_gen->reset_after_change();
2016   old_space->set_top(new_top);
2017   old_space->set_end(new_top);
2018   old_gen->reset_after_change();
2019 
2020   // Update the object start array for the filler object and the data from eden.
2021   ObjectStartArray* const start_array = old_gen->start_array();
2022   for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) {
2023     start_array->allocate_block(p);
2024   }
2025 
2026   // Could update the promoted average here, but it is not typically updated at
2027   // full GCs and the value to use is unclear.  Something like
2028   //
2029   // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc.
2030 
2031   size_policy->set_bytes_absorbed_from_eden(absorb_size);
2032   return true;
2033 }
2034 
2035 GCTaskManager* const PSParallelCompact::gc_task_manager() {
2036   assert(ParallelScavengeHeap::gc_task_manager() != NULL,
2037     "shouldn't return NULL");
2038   return ParallelScavengeHeap::gc_task_manager();
2039 }
2040 
2041 void PSParallelCompact::marking_phase(ParCompactionManager* cm,
2042                                       bool maximum_heap_compaction,
2043                                       ParallelOldTracer *gc_tracer) {
2044   // Recursively traverse all live objects and mark them
2045   GCTraceTime(Trace, gc, phases) tm("Marking Phase", &_gc_timer);
2046 
2047   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
2048   uint parallel_gc_threads = heap->gc_task_manager()->workers();
2049   uint active_gc_threads = heap->gc_task_manager()->active_workers();
2050   TaskQueueSetSuper* qset = ParCompactionManager::region_array();
2051   ParallelTaskTerminator terminator(active_gc_threads, qset);
2052 
2053   ParCompactionManager::MarkAndPushClosure mark_and_push_closure(cm);
2054   ParCompactionManager::FollowStackClosure follow_stack_closure(cm);
2055 
2056   // Need new claim bits before marking starts.
2057   ClassLoaderDataGraph::clear_claimed_marks();
2058 
2059   {
2060     GCTraceTime(Trace, gc, phases) tm("Par Mark", &_gc_timer);
2061 
2062     ParallelScavengeHeap::ParStrongRootsScope psrs;
2063 
2064     GCTaskQueue* q = GCTaskQueue::create();
2065 
2066     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::universe));
2067     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jni_handles));
2068     // We scan the thread roots in parallel
2069     Threads::create_thread_roots_marking_tasks(q);
2070     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::object_synchronizer));
2071     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::flat_profiler));
2072     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::management));
2073     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::system_dictionary));
2074     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::class_loader_data));
2075     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jvmti));
2076     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::code_cache));
2077 
2078     if (active_gc_threads > 1) {
2079       for (uint j = 0; j < active_gc_threads; j++) {
2080         q->enqueue(new StealMarkingTask(&terminator));
2081       }
2082     }
2083 
2084     gc_task_manager()->execute_and_wait(q);
2085   }
2086 
2087   // Process reference objects found during marking
2088   {
2089     GCTraceTime(Trace, gc, phases) tm("Reference Processing", &_gc_timer);
2090 
2091     ReferenceProcessorStats stats;
2092     if (ref_processor()->processing_is_mt()) {
2093       RefProcTaskExecutor task_executor;
2094       stats = ref_processor()->process_discovered_references(
2095         is_alive_closure(), &mark_and_push_closure, &follow_stack_closure,
2096         &task_executor, &_gc_timer);
2097     } else {
2098       stats = ref_processor()->process_discovered_references(
2099         is_alive_closure(), &mark_and_push_closure, &follow_stack_closure, NULL,
2100         &_gc_timer);
2101     }
2102 
2103     gc_tracer->report_gc_reference_stats(stats);
2104   }
2105 
2106   GCTraceTime(Trace, gc) tm_m("Class Unloading", &_gc_timer);
2107 
2108   // This is the point where the entire marking should have completed.
2109   assert(cm->marking_stacks_empty(), "Marking should have completed");
2110 
2111   // Follow system dictionary roots and unload classes.
2112   bool purged_class = SystemDictionary::do_unloading(is_alive_closure());
2113 
2114   // Unload nmethods.
2115   CodeCache::do_unloading(is_alive_closure(), purged_class);
2116 
2117   // Prune dead klasses from subklass/sibling/implementor lists.
2118   Klass::clean_weak_klass_links(is_alive_closure());
2119 
2120   // Delete entries for dead interned strings.
2121   StringTable::unlink(is_alive_closure());
2122 
2123   // Clean up unreferenced symbols in symbol table.
2124   SymbolTable::unlink();
2125   _gc_tracer.report_object_count_after_gc(is_alive_closure());
2126 }
2127 
2128 // This should be moved to the shared markSweep code!
2129 class PSAlwaysTrueClosure: public BoolObjectClosure {
2130 public:
2131   bool do_object_b(oop p) { return true; }
2132 };
2133 static PSAlwaysTrueClosure always_true;
2134 
2135 void PSParallelCompact::adjust_roots(ParCompactionManager* cm) {
2136   // Adjust the pointers to reflect the new locations
2137   GCTraceTime(Trace, gc, phases) tm("Adjust Roots", &_gc_timer);
2138 
2139   // Need new claim bits when tracing through and adjusting pointers.
2140   ClassLoaderDataGraph::clear_claimed_marks();
2141 
2142   PSParallelCompact::AdjustPointerClosure oop_closure(cm);
2143   PSParallelCompact::AdjustKlassClosure klass_closure(cm);
2144 
2145   // General strong roots.
2146   Universe::oops_do(&oop_closure);
2147   JNIHandles::oops_do(&oop_closure);   // Global (strong) JNI handles
2148   CLDToOopClosure adjust_from_cld(&oop_closure);
2149   Threads::oops_do(&oop_closure, &adjust_from_cld, NULL);
2150   ObjectSynchronizer::oops_do(&oop_closure);
2151   FlatProfiler::oops_do(&oop_closure);
2152   Management::oops_do(&oop_closure);
2153   JvmtiExport::oops_do(&oop_closure);
2154   SystemDictionary::oops_do(&oop_closure);
2155   ClassLoaderDataGraph::oops_do(&oop_closure, &klass_closure, true);
2156 
2157   // Now adjust pointers in remaining weak roots.  (All of which should
2158   // have been cleared if they pointed to non-surviving objects.)
2159   // Global (weak) JNI handles
2160   JNIHandles::weak_oops_do(&always_true, &oop_closure);
2161 
2162   CodeBlobToOopClosure adjust_from_blobs(&oop_closure, CodeBlobToOopClosure::FixRelocations);
2163   CodeCache::blobs_do(&adjust_from_blobs);
2164   StringTable::oops_do(&oop_closure);
2165   ref_processor()->weak_oops_do(&oop_closure);
2166   // Roots were visited so references into the young gen in roots
2167   // may have been scanned.  Process them also.
2168   // Should the reference processor have a span that excludes
2169   // young gen objects?
2170   PSScavenge::reference_processor()->weak_oops_do(&oop_closure);
2171 }
2172 
2173 // Helper class to print 8 region numbers per line and then print the total at the end.
2174 class FillableRegionLogger : public StackObj {
2175 private:
2176   LogHandle(gc, compaction) log;
2177   static const int LineLength = 8;
2178   size_t _regions[LineLength];
2179   int _next_index;
2180   bool _enabled;
2181   size_t _total_regions;
2182 public:
2183   FillableRegionLogger() : _next_index(0), _total_regions(0), _enabled(log_develop_is_enabled(Trace, gc, compaction)) { }
2184   ~FillableRegionLogger() {
2185     log.trace(SIZE_FORMAT " initially fillable regions", _total_regions);
2186   }
2187 
2188   void print_line() {
2189     if (!_enabled || _next_index == 0) {
2190       return;
2191     }
2192     FormatBuffer<> line("Fillable: ");
2193     for (int i = 0; i < _next_index; i++) {
2194       line.append(" " SIZE_FORMAT_W(7), _regions[i]);
2195     }
2196     log.trace("%s", line.buffer());
2197     _next_index = 0;
2198   }
2199 
2200   void handle(size_t region) {
2201     if (!_enabled) {
2202       return;
2203     }
2204     _regions[_next_index++] = region;
2205     if (_next_index == LineLength) {
2206       print_line();
2207     }
2208     _total_regions++;
2209   }
2210 };
2211 
2212 void PSParallelCompact::enqueue_region_draining_tasks(GCTaskQueue* q,
2213                                                       uint parallel_gc_threads)
2214 {
2215   GCTraceTime(Trace, gc, phases) tm("Drain Task Setup", &_gc_timer);
2216 
2217   // Find the threads that are active
2218   unsigned int which = 0;
2219 
2220   const uint task_count = MAX2(parallel_gc_threads, 1U);
2221   for (uint j = 0; j < task_count; j++) {
2222     q->enqueue(new DrainStacksCompactionTask(j));
2223     ParCompactionManager::verify_region_list_empty(j);
2224     // Set the region stacks variables to "no" region stack values
2225     // so that they will be recognized and needing a region stack
2226     // in the stealing tasks if they do not get one by executing
2227     // a draining stack.
2228     ParCompactionManager* cm = ParCompactionManager::manager_array(j);
2229     cm->set_region_stack(NULL);
2230     cm->set_region_stack_index((uint)max_uintx);
2231   }
2232   ParCompactionManager::reset_recycled_stack_index();
2233 
2234   // Find all regions that are available (can be filled immediately) and
2235   // distribute them to the thread stacks.  The iteration is done in reverse
2236   // order (high to low) so the regions will be removed in ascending order.
2237 
2238   const ParallelCompactData& sd = PSParallelCompact::summary_data();
2239 
2240   // A region index which corresponds to the tasks created above.
2241   // "which" must be 0 <= which < task_count
2242 
2243   which = 0;
2244   // id + 1 is used to test termination so unsigned  can
2245   // be used with an old_space_id == 0.
2246   FillableRegionLogger region_logger;
2247   for (unsigned int id = to_space_id; id + 1 > old_space_id; --id) {
2248     SpaceInfo* const space_info = _space_info + id;
2249     MutableSpace* const space = space_info->space();
2250     HeapWord* const new_top = space_info->new_top();
2251 
2252     const size_t beg_region = sd.addr_to_region_idx(space_info->dense_prefix());
2253     const size_t end_region =
2254       sd.addr_to_region_idx(sd.region_align_up(new_top));
2255 
2256     for (size_t cur = end_region - 1; cur + 1 > beg_region; --cur) {
2257       if (sd.region(cur)->claim_unsafe()) {
2258         ParCompactionManager::region_list_push(which, cur);
2259         region_logger.handle(cur);
2260         // Assign regions to tasks in round-robin fashion.
2261         if (++which == task_count) {
2262           assert(which <= parallel_gc_threads,
2263             "Inconsistent number of workers");
2264           which = 0;
2265         }
2266       }
2267     }
2268     region_logger.print_line();
2269   }
2270 }
2271 
2272 #define PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING 4
2273 
2274 void PSParallelCompact::enqueue_dense_prefix_tasks(GCTaskQueue* q,
2275                                                     uint parallel_gc_threads) {
2276   GCTraceTime(Trace, gc, phases) tm("Dense Prefix Task Setup", &_gc_timer);
2277 
2278   ParallelCompactData& sd = PSParallelCompact::summary_data();
2279 
2280   // Iterate over all the spaces adding tasks for updating
2281   // regions in the dense prefix.  Assume that 1 gc thread
2282   // will work on opening the gaps and the remaining gc threads
2283   // will work on the dense prefix.
2284   unsigned int space_id;
2285   for (space_id = old_space_id; space_id < last_space_id; ++ space_id) {
2286     HeapWord* const dense_prefix_end = _space_info[space_id].dense_prefix();
2287     const MutableSpace* const space = _space_info[space_id].space();
2288 
2289     if (dense_prefix_end == space->bottom()) {
2290       // There is no dense prefix for this space.
2291       continue;
2292     }
2293 
2294     // The dense prefix is before this region.
2295     size_t region_index_end_dense_prefix =
2296         sd.addr_to_region_idx(dense_prefix_end);
2297     RegionData* const dense_prefix_cp =
2298       sd.region(region_index_end_dense_prefix);
2299     assert(dense_prefix_end == space->end() ||
2300            dense_prefix_cp->available() ||
2301            dense_prefix_cp->claimed(),
2302            "The region after the dense prefix should always be ready to fill");
2303 
2304     size_t region_index_start = sd.addr_to_region_idx(space->bottom());
2305 
2306     // Is there dense prefix work?
2307     size_t total_dense_prefix_regions =
2308       region_index_end_dense_prefix - region_index_start;
2309     // How many regions of the dense prefix should be given to
2310     // each thread?
2311     if (total_dense_prefix_regions > 0) {
2312       uint tasks_for_dense_prefix = 1;
2313       if (total_dense_prefix_regions <=
2314           (parallel_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING)) {
2315         // Don't over partition.  This assumes that
2316         // PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING is a small integer value
2317         // so there are not many regions to process.
2318         tasks_for_dense_prefix = parallel_gc_threads;
2319       } else {
2320         // Over partition
2321         tasks_for_dense_prefix = parallel_gc_threads *
2322           PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING;
2323       }
2324       size_t regions_per_thread = total_dense_prefix_regions /
2325         tasks_for_dense_prefix;
2326       // Give each thread at least 1 region.
2327       if (regions_per_thread == 0) {
2328         regions_per_thread = 1;
2329       }
2330 
2331       for (uint k = 0; k < tasks_for_dense_prefix; k++) {
2332         if (region_index_start >= region_index_end_dense_prefix) {
2333           break;
2334         }
2335         // region_index_end is not processed
2336         size_t region_index_end = MIN2(region_index_start + regions_per_thread,
2337                                        region_index_end_dense_prefix);
2338         q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id),
2339                                              region_index_start,
2340                                              region_index_end));
2341         region_index_start = region_index_end;
2342       }
2343     }
2344     // This gets any part of the dense prefix that did not
2345     // fit evenly.
2346     if (region_index_start < region_index_end_dense_prefix) {
2347       q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id),
2348                                            region_index_start,
2349                                            region_index_end_dense_prefix));
2350     }
2351   }
2352 }
2353 
2354 void PSParallelCompact::enqueue_region_stealing_tasks(
2355                                      GCTaskQueue* q,
2356                                      ParallelTaskTerminator* terminator_ptr,
2357                                      uint parallel_gc_threads) {
2358   GCTraceTime(Trace, gc, phases) tm("Steal Task Setup", &_gc_timer);
2359 
2360   // Once a thread has drained it's stack, it should try to steal regions from
2361   // other threads.
2362   if (parallel_gc_threads > 1) {
2363     for (uint j = 0; j < parallel_gc_threads; j++) {
2364       q->enqueue(new StealRegionCompactionTask(terminator_ptr));
2365     }
2366   }
2367 }
2368 
2369 #ifdef ASSERT
2370 // Write a histogram of the number of times the block table was filled for a
2371 // region.
2372 void PSParallelCompact::write_block_fill_histogram()
2373 {
2374   if (!log_develop_is_enabled(Trace, gc, compaction)) {
2375     return;
2376   }
2377 
2378   LogHandle(gc, compaction) log;
2379   ResourceMark rm;
2380   outputStream* out = log.trace_stream();
2381 
2382   typedef ParallelCompactData::RegionData rd_t;
2383   ParallelCompactData& sd = summary_data();
2384 
2385   for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2386     MutableSpace* const spc = _space_info[id].space();
2387     if (spc->bottom() != spc->top()) {
2388       const rd_t* const beg = sd.addr_to_region_ptr(spc->bottom());
2389       HeapWord* const top_aligned_up = sd.region_align_up(spc->top());
2390       const rd_t* const end = sd.addr_to_region_ptr(top_aligned_up);
2391 
2392       size_t histo[5] = { 0, 0, 0, 0, 0 };
2393       const size_t histo_len = sizeof(histo) / sizeof(size_t);
2394       const size_t region_cnt = pointer_delta(end, beg, sizeof(rd_t));
2395 
2396       for (const rd_t* cur = beg; cur < end; ++cur) {
2397         ++histo[MIN2(cur->blocks_filled_count(), histo_len - 1)];
2398       }
2399       out->print("Block fill histogram: %u %-4s" SIZE_FORMAT_W(5), id, space_names[id], region_cnt);
2400       for (size_t i = 0; i < histo_len; ++i) {
2401         out->print(" " SIZE_FORMAT_W(5) " %5.1f%%",
2402                    histo[i], 100.0 * histo[i] / region_cnt);
2403       }
2404       out->cr();
2405     }
2406   }
2407 }
2408 #endif // #ifdef ASSERT
2409 
2410 void PSParallelCompact::compact() {
2411   GCTraceTime(Trace, gc, phases) tm("Compaction Phase", &_gc_timer);
2412 
2413   ParallelScavengeHeap* heap = ParallelScavengeHeap::heap();
2414   PSOldGen* old_gen = heap->old_gen();
2415   old_gen->start_array()->reset();
2416   uint parallel_gc_threads = heap->gc_task_manager()->workers();
2417   uint active_gc_threads = heap->gc_task_manager()->active_workers();
2418   TaskQueueSetSuper* qset = ParCompactionManager::region_array();
2419   ParallelTaskTerminator terminator(active_gc_threads, qset);
2420 
2421   GCTaskQueue* q = GCTaskQueue::create();
2422   enqueue_region_draining_tasks(q, active_gc_threads);
2423   enqueue_dense_prefix_tasks(q, active_gc_threads);
2424   enqueue_region_stealing_tasks(q, &terminator, active_gc_threads);
2425 
2426   {
2427     GCTraceTime(Trace, gc, phases) tm("Par Compact", &_gc_timer);
2428 
2429     gc_task_manager()->execute_and_wait(q);
2430 
2431 #ifdef  ASSERT
2432     // Verify that all regions have been processed before the deferred updates.
2433     for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2434       verify_complete(SpaceId(id));
2435     }
2436 #endif
2437   }
2438 
2439   {
2440     // Update the deferred objects, if any.  Any compaction manager can be used.
2441     GCTraceTime(Trace, gc, phases) tm("Deferred Updates", &_gc_timer);
2442     ParCompactionManager* cm = ParCompactionManager::manager_array(0);
2443     for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2444       update_deferred_objects(cm, SpaceId(id));
2445     }
2446   }
2447 
2448   DEBUG_ONLY(write_block_fill_histogram());
2449 }
2450 
2451 #ifdef  ASSERT
2452 void PSParallelCompact::verify_complete(SpaceId space_id) {
2453   // All Regions between space bottom() to new_top() should be marked as filled
2454   // and all Regions between new_top() and top() should be available (i.e.,
2455   // should have been emptied).
2456   ParallelCompactData& sd = summary_data();
2457   SpaceInfo si = _space_info[space_id];
2458   HeapWord* new_top_addr = sd.region_align_up(si.new_top());
2459   HeapWord* old_top_addr = sd.region_align_up(si.space()->top());
2460   const size_t beg_region = sd.addr_to_region_idx(si.space()->bottom());
2461   const size_t new_top_region = sd.addr_to_region_idx(new_top_addr);
2462   const size_t old_top_region = sd.addr_to_region_idx(old_top_addr);
2463 
2464   bool issued_a_warning = false;
2465 
2466   size_t cur_region;
2467   for (cur_region = beg_region; cur_region < new_top_region; ++cur_region) {
2468     const RegionData* const c = sd.region(cur_region);
2469     if (!c->completed()) {
2470       warning("region " SIZE_FORMAT " not filled:  "
2471               "destination_count=%u",
2472               cur_region, c->destination_count());
2473       issued_a_warning = true;
2474     }
2475   }
2476 
2477   for (cur_region = new_top_region; cur_region < old_top_region; ++cur_region) {
2478     const RegionData* const c = sd.region(cur_region);
2479     if (!c->available()) {
2480       warning("region " SIZE_FORMAT " not empty:   "
2481               "destination_count=%u",
2482               cur_region, c->destination_count());
2483       issued_a_warning = true;
2484     }
2485   }
2486 
2487   if (issued_a_warning) {
2488     print_region_ranges();
2489   }
2490 }
2491 #endif  // #ifdef ASSERT
2492 
2493 inline void UpdateOnlyClosure::do_addr(HeapWord* addr) {
2494   _start_array->allocate_block(addr);
2495   compaction_manager()->update_contents(oop(addr));
2496 }
2497 
2498 // Update interior oops in the ranges of regions [beg_region, end_region).
2499 void
2500 PSParallelCompact::update_and_deadwood_in_dense_prefix(ParCompactionManager* cm,
2501                                                        SpaceId space_id,
2502                                                        size_t beg_region,
2503                                                        size_t end_region) {
2504   ParallelCompactData& sd = summary_data();
2505   ParMarkBitMap* const mbm = mark_bitmap();
2506 
2507   HeapWord* beg_addr = sd.region_to_addr(beg_region);
2508   HeapWord* const end_addr = sd.region_to_addr(end_region);
2509   assert(beg_region <= end_region, "bad region range");
2510   assert(end_addr <= dense_prefix(space_id), "not in the dense prefix");
2511 
2512 #ifdef  ASSERT
2513   // Claim the regions to avoid triggering an assert when they are marked as
2514   // filled.
2515   for (size_t claim_region = beg_region; claim_region < end_region; ++claim_region) {
2516     assert(sd.region(claim_region)->claim_unsafe(), "claim() failed");
2517   }
2518 #endif  // #ifdef ASSERT
2519 
2520   if (beg_addr != space(space_id)->bottom()) {
2521     // Find the first live object or block of dead space that *starts* in this
2522     // range of regions.  If a partial object crosses onto the region, skip it;
2523     // it will be marked for 'deferred update' when the object head is
2524     // processed.  If dead space crosses onto the region, it is also skipped; it
2525     // will be filled when the prior region is processed.  If neither of those
2526     // apply, the first word in the region is the start of a live object or dead
2527     // space.
2528     assert(beg_addr > space(space_id)->bottom(), "sanity");
2529     const RegionData* const cp = sd.region(beg_region);
2530     if (cp->partial_obj_size() != 0) {
2531       beg_addr = sd.partial_obj_end(beg_region);
2532     } else if (dead_space_crosses_boundary(cp, mbm->addr_to_bit(beg_addr))) {
2533       beg_addr = mbm->find_obj_beg(beg_addr, end_addr);
2534     }
2535   }
2536 
2537   if (beg_addr < end_addr) {
2538     // A live object or block of dead space starts in this range of Regions.
2539      HeapWord* const dense_prefix_end = dense_prefix(space_id);
2540 
2541     // Create closures and iterate.
2542     UpdateOnlyClosure update_closure(mbm, cm, space_id);
2543     FillClosure fill_closure(cm, space_id);
2544     ParMarkBitMap::IterationStatus status;
2545     status = mbm->iterate(&update_closure, &fill_closure, beg_addr, end_addr,
2546                           dense_prefix_end);
2547     if (status == ParMarkBitMap::incomplete) {
2548       update_closure.do_addr(update_closure.source());
2549     }
2550   }
2551 
2552   // Mark the regions as filled.
2553   RegionData* const beg_cp = sd.region(beg_region);
2554   RegionData* const end_cp = sd.region(end_region);
2555   for (RegionData* cp = beg_cp; cp < end_cp; ++cp) {
2556     cp->set_completed();
2557   }
2558 }
2559 
2560 // Return the SpaceId for the space containing addr.  If addr is not in the
2561 // heap, last_space_id is returned.  In debug mode it expects the address to be
2562 // in the heap and asserts such.
2563 PSParallelCompact::SpaceId PSParallelCompact::space_id(HeapWord* addr) {
2564   assert(ParallelScavengeHeap::heap()->is_in_reserved(addr), "addr not in the heap");
2565 
2566   for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2567     if (_space_info[id].space()->contains(addr)) {
2568       return SpaceId(id);
2569     }
2570   }
2571 
2572   assert(false, "no space contains the addr");
2573   return last_space_id;
2574 }
2575 
2576 void PSParallelCompact::update_deferred_objects(ParCompactionManager* cm,
2577                                                 SpaceId id) {
2578   assert(id < last_space_id, "bad space id");
2579 
2580   ParallelCompactData& sd = summary_data();
2581   const SpaceInfo* const space_info = _space_info + id;
2582   ObjectStartArray* const start_array = space_info->start_array();
2583 
2584   const MutableSpace* const space = space_info->space();
2585   assert(space_info->dense_prefix() >= space->bottom(), "dense_prefix not set");
2586   HeapWord* const beg_addr = space_info->dense_prefix();
2587   HeapWord* const end_addr = sd.region_align_up(space_info->new_top());
2588 
2589   const RegionData* const beg_region = sd.addr_to_region_ptr(beg_addr);
2590   const RegionData* const end_region = sd.addr_to_region_ptr(end_addr);
2591   const RegionData* cur_region;
2592   for (cur_region = beg_region; cur_region < end_region; ++cur_region) {
2593     HeapWord* const addr = cur_region->deferred_obj_addr();
2594     if (addr != NULL) {
2595       if (start_array != NULL) {
2596         start_array->allocate_block(addr);
2597       }
2598       cm->update_contents(oop(addr));
2599       assert(oop(addr)->is_oop_or_null(), "Expected an oop or NULL at " PTR_FORMAT, p2i(oop(addr)));
2600     }
2601   }
2602 }
2603 
2604 // Skip over count live words starting from beg, and return the address of the
2605 // next live word.  Unless marked, the word corresponding to beg is assumed to
2606 // be dead.  Callers must either ensure beg does not correspond to the middle of
2607 // an object, or account for those live words in some other way.  Callers must
2608 // also ensure that there are enough live words in the range [beg, end) to skip.
2609 HeapWord*
2610 PSParallelCompact::skip_live_words(HeapWord* beg, HeapWord* end, size_t count)
2611 {
2612   assert(count > 0, "sanity");
2613 
2614   ParMarkBitMap* m = mark_bitmap();
2615   idx_t bits_to_skip = m->words_to_bits(count);
2616   idx_t cur_beg = m->addr_to_bit(beg);
2617   const idx_t search_end = BitMap::word_align_up(m->addr_to_bit(end));
2618 
2619   do {
2620     cur_beg = m->find_obj_beg(cur_beg, search_end);
2621     idx_t cur_end = m->find_obj_end(cur_beg, search_end);
2622     const size_t obj_bits = cur_end - cur_beg + 1;
2623     if (obj_bits > bits_to_skip) {
2624       return m->bit_to_addr(cur_beg + bits_to_skip);
2625     }
2626     bits_to_skip -= obj_bits;
2627     cur_beg = cur_end + 1;
2628   } while (bits_to_skip > 0);
2629 
2630   // Skipping the desired number of words landed just past the end of an object.
2631   // Find the start of the next object.
2632   cur_beg = m->find_obj_beg(cur_beg, search_end);
2633   assert(cur_beg < m->addr_to_bit(end), "not enough live words to skip");
2634   return m->bit_to_addr(cur_beg);
2635 }
2636 
2637 HeapWord* PSParallelCompact::first_src_addr(HeapWord* const dest_addr,
2638                                             SpaceId src_space_id,
2639                                             size_t src_region_idx)
2640 {
2641   assert(summary_data().is_region_aligned(dest_addr), "not aligned");
2642 
2643   const SplitInfo& split_info = _space_info[src_space_id].split_info();
2644   if (split_info.dest_region_addr() == dest_addr) {
2645     // The partial object ending at the split point contains the first word to
2646     // be copied to dest_addr.
2647     return split_info.first_src_addr();
2648   }
2649 
2650   const ParallelCompactData& sd = summary_data();
2651   ParMarkBitMap* const bitmap = mark_bitmap();
2652   const size_t RegionSize = ParallelCompactData::RegionSize;
2653 
2654   assert(sd.is_region_aligned(dest_addr), "not aligned");
2655   const RegionData* const src_region_ptr = sd.region(src_region_idx);
2656   const size_t partial_obj_size = src_region_ptr->partial_obj_size();
2657   HeapWord* const src_region_destination = src_region_ptr->destination();
2658 
2659   assert(dest_addr >= src_region_destination, "wrong src region");
2660   assert(src_region_ptr->data_size() > 0, "src region cannot be empty");
2661 
2662   HeapWord* const src_region_beg = sd.region_to_addr(src_region_idx);
2663   HeapWord* const src_region_end = src_region_beg + RegionSize;
2664 
2665   HeapWord* addr = src_region_beg;
2666   if (dest_addr == src_region_destination) {
2667     // Return the first live word in the source region.
2668     if (partial_obj_size == 0) {
2669       addr = bitmap->find_obj_beg(addr, src_region_end);
2670       assert(addr < src_region_end, "no objects start in src region");
2671     }
2672     return addr;
2673   }
2674 
2675   // Must skip some live data.
2676   size_t words_to_skip = dest_addr - src_region_destination;
2677   assert(src_region_ptr->data_size() > words_to_skip, "wrong src region");
2678 
2679   if (partial_obj_size >= words_to_skip) {
2680     // All the live words to skip are part of the partial object.
2681     addr += words_to_skip;
2682     if (partial_obj_size == words_to_skip) {
2683       // Find the first live word past the partial object.
2684       addr = bitmap->find_obj_beg(addr, src_region_end);
2685       assert(addr < src_region_end, "wrong src region");
2686     }
2687     return addr;
2688   }
2689 
2690   // Skip over the partial object (if any).
2691   if (partial_obj_size != 0) {
2692     words_to_skip -= partial_obj_size;
2693     addr += partial_obj_size;
2694   }
2695 
2696   // Skip over live words due to objects that start in the region.
2697   addr = skip_live_words(addr, src_region_end, words_to_skip);
2698   assert(addr < src_region_end, "wrong src region");
2699   return addr;
2700 }
2701 
2702 void PSParallelCompact::decrement_destination_counts(ParCompactionManager* cm,
2703                                                      SpaceId src_space_id,
2704                                                      size_t beg_region,
2705                                                      HeapWord* end_addr)
2706 {
2707   ParallelCompactData& sd = summary_data();
2708 
2709 #ifdef ASSERT
2710   MutableSpace* const src_space = _space_info[src_space_id].space();
2711   HeapWord* const beg_addr = sd.region_to_addr(beg_region);
2712   assert(src_space->contains(beg_addr) || beg_addr == src_space->end(),
2713          "src_space_id does not match beg_addr");
2714   assert(src_space->contains(end_addr) || end_addr == src_space->end(),
2715          "src_space_id does not match end_addr");
2716 #endif // #ifdef ASSERT
2717 
2718   RegionData* const beg = sd.region(beg_region);
2719   RegionData* const end = sd.addr_to_region_ptr(sd.region_align_up(end_addr));
2720 
2721   // Regions up to new_top() are enqueued if they become available.
2722   HeapWord* const new_top = _space_info[src_space_id].new_top();
2723   RegionData* const enqueue_end =
2724     sd.addr_to_region_ptr(sd.region_align_up(new_top));
2725 
2726   for (RegionData* cur = beg; cur < end; ++cur) {
2727     assert(cur->data_size() > 0, "region must have live data");
2728     cur->decrement_destination_count();
2729     if (cur < enqueue_end && cur->available() && cur->claim()) {
2730       cm->push_region(sd.region(cur));
2731     }
2732   }
2733 }
2734 
2735 size_t PSParallelCompact::next_src_region(MoveAndUpdateClosure& closure,
2736                                           SpaceId& src_space_id,
2737                                           HeapWord*& src_space_top,
2738                                           HeapWord* end_addr)
2739 {
2740   typedef ParallelCompactData::RegionData RegionData;
2741 
2742   ParallelCompactData& sd = PSParallelCompact::summary_data();
2743   const size_t region_size = ParallelCompactData::RegionSize;
2744 
2745   size_t src_region_idx = 0;
2746 
2747   // Skip empty regions (if any) up to the top of the space.
2748   HeapWord* const src_aligned_up = sd.region_align_up(end_addr);
2749   RegionData* src_region_ptr = sd.addr_to_region_ptr(src_aligned_up);
2750   HeapWord* const top_aligned_up = sd.region_align_up(src_space_top);
2751   const RegionData* const top_region_ptr =
2752     sd.addr_to_region_ptr(top_aligned_up);
2753   while (src_region_ptr < top_region_ptr && src_region_ptr->data_size() == 0) {
2754     ++src_region_ptr;
2755   }
2756 
2757   if (src_region_ptr < top_region_ptr) {
2758     // The next source region is in the current space.  Update src_region_idx
2759     // and the source address to match src_region_ptr.
2760     src_region_idx = sd.region(src_region_ptr);
2761     HeapWord* const src_region_addr = sd.region_to_addr(src_region_idx);
2762     if (src_region_addr > closure.source()) {
2763       closure.set_source(src_region_addr);
2764     }
2765     return src_region_idx;
2766   }
2767 
2768   // Switch to a new source space and find the first non-empty region.
2769   unsigned int space_id = src_space_id + 1;
2770   assert(space_id < last_space_id, "not enough spaces");
2771 
2772   HeapWord* const destination = closure.destination();
2773 
2774   do {
2775     MutableSpace* space = _space_info[space_id].space();
2776     HeapWord* const bottom = space->bottom();
2777     const RegionData* const bottom_cp = sd.addr_to_region_ptr(bottom);
2778 
2779     // Iterate over the spaces that do not compact into themselves.
2780     if (bottom_cp->destination() != bottom) {
2781       HeapWord* const top_aligned_up = sd.region_align_up(space->top());
2782       const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
2783 
2784       for (const RegionData* src_cp = bottom_cp; src_cp < top_cp; ++src_cp) {
2785         if (src_cp->live_obj_size() > 0) {
2786           // Found it.
2787           assert(src_cp->destination() == destination,
2788                  "first live obj in the space must match the destination");
2789           assert(src_cp->partial_obj_size() == 0,
2790                  "a space cannot begin with a partial obj");
2791 
2792           src_space_id = SpaceId(space_id);
2793           src_space_top = space->top();
2794           const size_t src_region_idx = sd.region(src_cp);
2795           closure.set_source(sd.region_to_addr(src_region_idx));
2796           return src_region_idx;
2797         } else {
2798           assert(src_cp->data_size() == 0, "sanity");
2799         }
2800       }
2801     }
2802   } while (++space_id < last_space_id);
2803 
2804   assert(false, "no source region was found");
2805   return 0;
2806 }
2807 
2808 void PSParallelCompact::fill_region(ParCompactionManager* cm, size_t region_idx)
2809 {
2810   typedef ParMarkBitMap::IterationStatus IterationStatus;
2811   const size_t RegionSize = ParallelCompactData::RegionSize;
2812   ParMarkBitMap* const bitmap = mark_bitmap();
2813   ParallelCompactData& sd = summary_data();
2814   RegionData* const region_ptr = sd.region(region_idx);
2815 
2816   // Get the items needed to construct the closure.
2817   HeapWord* dest_addr = sd.region_to_addr(region_idx);
2818   SpaceId dest_space_id = space_id(dest_addr);
2819   ObjectStartArray* start_array = _space_info[dest_space_id].start_array();
2820   HeapWord* new_top = _space_info[dest_space_id].new_top();
2821   assert(dest_addr < new_top, "sanity");
2822   const size_t words = MIN2(pointer_delta(new_top, dest_addr), RegionSize);
2823 
2824   // Get the source region and related info.
2825   size_t src_region_idx = region_ptr->source_region();
2826   SpaceId src_space_id = space_id(sd.region_to_addr(src_region_idx));
2827   HeapWord* src_space_top = _space_info[src_space_id].space()->top();
2828 
2829   MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words);
2830   closure.set_source(first_src_addr(dest_addr, src_space_id, src_region_idx));
2831 
2832   // Adjust src_region_idx to prepare for decrementing destination counts (the
2833   // destination count is not decremented when a region is copied to itself).
2834   if (src_region_idx == region_idx) {
2835     src_region_idx += 1;
2836   }
2837 
2838   if (bitmap->is_unmarked(closure.source())) {
2839     // The first source word is in the middle of an object; copy the remainder
2840     // of the object or as much as will fit.  The fact that pointer updates were
2841     // deferred will be noted when the object header is processed.
2842     HeapWord* const old_src_addr = closure.source();
2843     closure.copy_partial_obj();
2844     if (closure.is_full()) {
2845       decrement_destination_counts(cm, src_space_id, src_region_idx,
2846                                    closure.source());
2847       region_ptr->set_deferred_obj_addr(NULL);
2848       region_ptr->set_completed();
2849       return;
2850     }
2851 
2852     HeapWord* const end_addr = sd.region_align_down(closure.source());
2853     if (sd.region_align_down(old_src_addr) != end_addr) {
2854       // The partial object was copied from more than one source region.
2855       decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
2856 
2857       // Move to the next source region, possibly switching spaces as well.  All
2858       // args except end_addr may be modified.
2859       src_region_idx = next_src_region(closure, src_space_id, src_space_top,
2860                                        end_addr);
2861     }
2862   }
2863 
2864   do {
2865     HeapWord* const cur_addr = closure.source();
2866     HeapWord* const end_addr = MIN2(sd.region_align_up(cur_addr + 1),
2867                                     src_space_top);
2868     IterationStatus status = bitmap->iterate(&closure, cur_addr, end_addr);
2869 
2870     if (status == ParMarkBitMap::incomplete) {
2871       // The last obj that starts in the source region does not end in the
2872       // region.
2873       assert(closure.source() < end_addr, "sanity");
2874       HeapWord* const obj_beg = closure.source();
2875       HeapWord* const range_end = MIN2(obj_beg + closure.words_remaining(),
2876                                        src_space_top);
2877       HeapWord* const obj_end = bitmap->find_obj_end(obj_beg, range_end);
2878       if (obj_end < range_end) {
2879         // The end was found; the entire object will fit.
2880         status = closure.do_addr(obj_beg, bitmap->obj_size(obj_beg, obj_end));
2881         assert(status != ParMarkBitMap::would_overflow, "sanity");
2882       } else {
2883         // The end was not found; the object will not fit.
2884         assert(range_end < src_space_top, "obj cannot cross space boundary");
2885         status = ParMarkBitMap::would_overflow;
2886       }
2887     }
2888 
2889     if (status == ParMarkBitMap::would_overflow) {
2890       // The last object did not fit.  Note that interior oop updates were
2891       // deferred, then copy enough of the object to fill the region.
2892       region_ptr->set_deferred_obj_addr(closure.destination());
2893       status = closure.copy_until_full(); // copies from closure.source()
2894 
2895       decrement_destination_counts(cm, src_space_id, src_region_idx,
2896                                    closure.source());
2897       region_ptr->set_completed();
2898       return;
2899     }
2900 
2901     if (status == ParMarkBitMap::full) {
2902       decrement_destination_counts(cm, src_space_id, src_region_idx,
2903                                    closure.source());
2904       region_ptr->set_deferred_obj_addr(NULL);
2905       region_ptr->set_completed();
2906       return;
2907     }
2908 
2909     decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
2910 
2911     // Move to the next source region, possibly switching spaces as well.  All
2912     // args except end_addr may be modified.
2913     src_region_idx = next_src_region(closure, src_space_id, src_space_top,
2914                                      end_addr);
2915   } while (true);
2916 }
2917 
2918 void PSParallelCompact::fill_blocks(size_t region_idx)
2919 {
2920   // Fill in the block table elements for the specified region.  Each block
2921   // table element holds the number of live words in the region that are to the
2922   // left of the first object that starts in the block.  Thus only blocks in
2923   // which an object starts need to be filled.
2924   //
2925   // The algorithm scans the section of the bitmap that corresponds to the
2926   // region, keeping a running total of the live words.  When an object start is
2927   // found, if it's the first to start in the block that contains it, the
2928   // current total is written to the block table element.
2929   const size_t Log2BlockSize = ParallelCompactData::Log2BlockSize;
2930   const size_t Log2RegionSize = ParallelCompactData::Log2RegionSize;
2931   const size_t RegionSize = ParallelCompactData::RegionSize;
2932 
2933   ParallelCompactData& sd = summary_data();
2934   const size_t partial_obj_size = sd.region(region_idx)->partial_obj_size();
2935   if (partial_obj_size >= RegionSize) {
2936     return; // No objects start in this region.
2937   }
2938 
2939   // Ensure the first loop iteration decides that the block has changed.
2940   size_t cur_block = sd.block_count();
2941 
2942   const ParMarkBitMap* const bitmap = mark_bitmap();
2943 
2944   const size_t Log2BitsPerBlock = Log2BlockSize - LogMinObjAlignment;
2945   assert((size_t)1 << Log2BitsPerBlock ==
2946          bitmap->words_to_bits(ParallelCompactData::BlockSize), "sanity");
2947 
2948   size_t beg_bit = bitmap->words_to_bits(region_idx << Log2RegionSize);
2949   const size_t range_end = beg_bit + bitmap->words_to_bits(RegionSize);
2950   size_t live_bits = bitmap->words_to_bits(partial_obj_size);
2951   beg_bit = bitmap->find_obj_beg(beg_bit + live_bits, range_end);
2952   while (beg_bit < range_end) {
2953     const size_t new_block = beg_bit >> Log2BitsPerBlock;
2954     if (new_block != cur_block) {
2955       cur_block = new_block;
2956       sd.block(cur_block)->set_offset(bitmap->bits_to_words(live_bits));
2957     }
2958 
2959     const size_t end_bit = bitmap->find_obj_end(beg_bit, range_end);
2960     if (end_bit < range_end - 1) {
2961       live_bits += end_bit - beg_bit + 1;
2962       beg_bit = bitmap->find_obj_beg(end_bit + 1, range_end);
2963     } else {
2964       return;
2965     }
2966   }
2967 }
2968 
2969 void
2970 PSParallelCompact::move_and_update(ParCompactionManager* cm, SpaceId space_id) {
2971   const MutableSpace* sp = space(space_id);
2972   if (sp->is_empty()) {
2973     return;
2974   }
2975 
2976   ParallelCompactData& sd = PSParallelCompact::summary_data();
2977   ParMarkBitMap* const bitmap = mark_bitmap();
2978   HeapWord* const dp_addr = dense_prefix(space_id);
2979   HeapWord* beg_addr = sp->bottom();
2980   HeapWord* end_addr = sp->top();
2981 
2982   assert(beg_addr <= dp_addr && dp_addr <= end_addr, "bad dense prefix");
2983 
2984   const size_t beg_region = sd.addr_to_region_idx(beg_addr);
2985   const size_t dp_region = sd.addr_to_region_idx(dp_addr);
2986   if (beg_region < dp_region) {
2987     update_and_deadwood_in_dense_prefix(cm, space_id, beg_region, dp_region);
2988   }
2989 
2990   // The destination of the first live object that starts in the region is one
2991   // past the end of the partial object entering the region (if any).
2992   HeapWord* const dest_addr = sd.partial_obj_end(dp_region);
2993   HeapWord* const new_top = _space_info[space_id].new_top();
2994   assert(new_top >= dest_addr, "bad new_top value");
2995   const size_t words = pointer_delta(new_top, dest_addr);
2996 
2997   if (words > 0) {
2998     ObjectStartArray* start_array = _space_info[space_id].start_array();
2999     MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words);
3000 
3001     ParMarkBitMap::IterationStatus status;
3002     status = bitmap->iterate(&closure, dest_addr, end_addr);
3003     assert(status == ParMarkBitMap::full, "iteration not complete");
3004     assert(bitmap->find_obj_beg(closure.source(), end_addr) == end_addr,
3005            "live objects skipped because closure is full");
3006   }
3007 }
3008 
3009 jlong PSParallelCompact::millis_since_last_gc() {
3010   // We need a monotonically non-decreasing time in ms but
3011   // os::javaTimeMillis() does not guarantee monotonicity.
3012   jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
3013   jlong ret_val = now - _time_of_last_gc;
3014   // XXX See note in genCollectedHeap::millis_since_last_gc().
3015   if (ret_val < 0) {
3016     NOT_PRODUCT(warning("time warp: " JLONG_FORMAT, ret_val);)
3017     return 0;
3018   }
3019   return ret_val;
3020 }
3021 
3022 void PSParallelCompact::reset_millis_since_last_gc() {
3023   // We need a monotonically non-decreasing time in ms but
3024   // os::javaTimeMillis() does not guarantee monotonicity.
3025   _time_of_last_gc = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
3026 }
3027 
3028 ParMarkBitMap::IterationStatus MoveAndUpdateClosure::copy_until_full()
3029 {
3030   if (source() != destination()) {
3031     DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3032     Copy::aligned_conjoint_words(source(), destination(), words_remaining());
3033   }
3034   update_state(words_remaining());
3035   assert(is_full(), "sanity");
3036   return ParMarkBitMap::full;
3037 }
3038 
3039 void MoveAndUpdateClosure::copy_partial_obj()
3040 {
3041   size_t words = words_remaining();
3042 
3043   HeapWord* const range_end = MIN2(source() + words, bitmap()->region_end());
3044   HeapWord* const end_addr = bitmap()->find_obj_end(source(), range_end);
3045   if (end_addr < range_end) {
3046     words = bitmap()->obj_size(source(), end_addr);
3047   }
3048 
3049   // This test is necessary; if omitted, the pointer updates to a partial object
3050   // that crosses the dense prefix boundary could be overwritten.
3051   if (source() != destination()) {
3052     DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3053     Copy::aligned_conjoint_words(source(), destination(), words);
3054   }
3055   update_state(words);
3056 }
3057 
3058 void InstanceKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) {
3059   PSParallelCompact::AdjustPointerClosure closure(cm);
3060   oop_oop_iterate_oop_maps<true>(obj, &closure);
3061 }
3062 
3063 void InstanceMirrorKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) {
3064   InstanceKlass::oop_pc_update_pointers(obj, cm);
3065 
3066   PSParallelCompact::AdjustPointerClosure closure(cm);
3067   oop_oop_iterate_statics<true>(obj, &closure);
3068 }
3069 
3070 void InstanceClassLoaderKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) {
3071   InstanceKlass::oop_pc_update_pointers(obj, cm);
3072 }
3073 
3074 #ifdef ASSERT
3075 template <class T> static void trace_reference_gc(const char *s, oop obj,
3076                                                   T* referent_addr,
3077                                                   T* next_addr,
3078                                                   T* discovered_addr) {
3079   log_develop_trace(gc, ref)("%s obj " PTR_FORMAT, s, p2i(obj));
3080   log_develop_trace(gc, ref)("     referent_addr/* " PTR_FORMAT " / " PTR_FORMAT,
3081                              p2i(referent_addr), referent_addr ? p2i(oopDesc::load_decode_heap_oop(referent_addr)) : NULL);
3082   log_develop_trace(gc, ref)("     next_addr/* " PTR_FORMAT " / " PTR_FORMAT,
3083                              p2i(next_addr), next_addr ? p2i(oopDesc::load_decode_heap_oop(next_addr)) : NULL);
3084   log_develop_trace(gc, ref)("     discovered_addr/* " PTR_FORMAT " / " PTR_FORMAT,
3085                              p2i(discovered_addr), discovered_addr ? p2i(oopDesc::load_decode_heap_oop(discovered_addr)) : NULL);
3086 }
3087 #endif
3088 
3089 template <class T>
3090 static void oop_pc_update_pointers_specialized(oop obj, ParCompactionManager* cm) {
3091   T* referent_addr = (T*)java_lang_ref_Reference::referent_addr(obj);
3092   PSParallelCompact::adjust_pointer(referent_addr, cm);
3093   T* next_addr = (T*)java_lang_ref_Reference::next_addr(obj);
3094   PSParallelCompact::adjust_pointer(next_addr, cm);
3095   T* discovered_addr = (T*)java_lang_ref_Reference::discovered_addr(obj);
3096   PSParallelCompact::adjust_pointer(discovered_addr, cm);
3097   debug_only(trace_reference_gc("InstanceRefKlass::oop_update_ptrs", obj,
3098                                 referent_addr, next_addr, discovered_addr);)
3099 }
3100 
3101 void InstanceRefKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) {
3102   InstanceKlass::oop_pc_update_pointers(obj, cm);
3103 
3104   if (UseCompressedOops) {
3105     oop_pc_update_pointers_specialized<narrowOop>(obj, cm);
3106   } else {
3107     oop_pc_update_pointers_specialized<oop>(obj, cm);
3108   }
3109 }
3110 
3111 void ObjArrayKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) {
3112   assert(obj->is_objArray(), "obj must be obj array");
3113   PSParallelCompact::AdjustPointerClosure closure(cm);
3114   oop_oop_iterate_elements<true>(objArrayOop(obj), &closure);
3115 }
3116 
3117 void TypeArrayKlass::oop_pc_update_pointers(oop obj, ParCompactionManager* cm) {
3118   assert(obj->is_typeArray(),"must be a type array");
3119 }
3120 
3121 ParMarkBitMapClosure::IterationStatus
3122 MoveAndUpdateClosure::do_addr(HeapWord* addr, size_t words) {
3123   assert(destination() != NULL, "sanity");
3124   assert(bitmap()->obj_size(addr) == words, "bad size");
3125 
3126   _source = addr;
3127   assert(PSParallelCompact::summary_data().calc_new_pointer(source(), compaction_manager()) ==
3128          destination(), "wrong destination");
3129 
3130   if (words > words_remaining()) {
3131     return ParMarkBitMap::would_overflow;
3132   }
3133 
3134   // The start_array must be updated even if the object is not moving.
3135   if (_start_array != NULL) {
3136     _start_array->allocate_block(destination());
3137   }
3138 
3139   if (destination() != source()) {
3140     DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3141     Copy::aligned_conjoint_words(source(), destination(), words);
3142   }
3143 
3144   oop moved_oop = (oop) destination();
3145   compaction_manager()->update_contents(moved_oop);
3146   assert(moved_oop->is_oop_or_null(), "Expected an oop or NULL at " PTR_FORMAT, p2i(moved_oop));
3147 
3148   update_state(words);
3149   assert(destination() == (HeapWord*)moved_oop + moved_oop->size(), "sanity");
3150   return is_full() ? ParMarkBitMap::full : ParMarkBitMap::incomplete;
3151 }
3152 
3153 UpdateOnlyClosure::UpdateOnlyClosure(ParMarkBitMap* mbm,
3154                                      ParCompactionManager* cm,
3155                                      PSParallelCompact::SpaceId space_id) :
3156   ParMarkBitMapClosure(mbm, cm),
3157   _space_id(space_id),
3158   _start_array(PSParallelCompact::start_array(space_id))
3159 {
3160 }
3161 
3162 // Updates the references in the object to their new values.
3163 ParMarkBitMapClosure::IterationStatus
3164 UpdateOnlyClosure::do_addr(HeapWord* addr, size_t words) {
3165   do_addr(addr);
3166   return ParMarkBitMap::incomplete;
3167 }
3168 
3169 ParMarkBitMapClosure::IterationStatus
3170 FillClosure::do_addr(HeapWord* addr, size_t size) {
3171   CollectedHeap::fill_with_objects(addr, size);
3172   HeapWord* const end = addr + size;
3173   do {
3174     _start_array->allocate_block(addr);
3175     addr += oop(addr)->size();
3176   } while (addr < end);
3177   return ParMarkBitMap::incomplete;
3178 }
--- EOF ---