1 /*
   2  * Copyright (c) 2005, 2012, 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/symbolTable.hpp"
  27 #include "classfile/systemDictionary.hpp"
  28 #include "code/codeCache.hpp"
  29 #include "gc_implementation/parallelScavenge/gcTaskManager.hpp"
  30 #include "gc_implementation/parallelScavenge/generationSizer.hpp"
  31 #include "gc_implementation/parallelScavenge/parallelScavengeHeap.inline.hpp"
  32 #include "gc_implementation/parallelScavenge/pcTasks.hpp"
  33 #include "gc_implementation/parallelScavenge/psAdaptiveSizePolicy.hpp"
  34 #include "gc_implementation/parallelScavenge/psCompactionManager.inline.hpp"
  35 #include "gc_implementation/parallelScavenge/psMarkSweep.hpp"
  36 #include "gc_implementation/parallelScavenge/psMarkSweepDecorator.hpp"
  37 #include "gc_implementation/parallelScavenge/psOldGen.hpp"
  38 #include "gc_implementation/parallelScavenge/psParallelCompact.hpp"
  39 #include "gc_implementation/parallelScavenge/psPermGen.hpp"
  40 #include "gc_implementation/parallelScavenge/psPromotionManager.inline.hpp"
  41 #include "gc_implementation/parallelScavenge/psScavenge.hpp"
  42 #include "gc_implementation/parallelScavenge/psYoungGen.hpp"
  43 #include "gc_implementation/shared/gcHeapSummary.hpp"
  44 #include "gc_implementation/shared/gcTimer.hpp"
  45 #include "gc_implementation/shared/gcTrace.hpp"
  46 #include "gc_implementation/shared/gcTraceTime.hpp"
  47 #include "gc_implementation/shared/isGCActiveMark.hpp"
  48 #include "gc_interface/gcCause.hpp"
  49 #include "memory/gcLocker.inline.hpp"
  50 #include "memory/referencePolicy.hpp"
  51 #include "memory/referenceProcessor.hpp"
  52 #include "oops/methodDataOop.hpp"
  53 #include "oops/oop.inline.hpp"
  54 #include "oops/oop.pcgc.inline.hpp"
  55 #include "runtime/fprofiler.hpp"
  56 #include "runtime/safepoint.hpp"
  57 #include "runtime/vmThread.hpp"
  58 #include "services/management.hpp"
  59 #include "services/memoryService.hpp"
  60 #include "services/memTracker.hpp"
  61 #include "utilities/events.hpp"
  62 #include "utilities/stack.inline.hpp"
  63 
  64 #include <math.h>
  65 
  66 // All sizes are in HeapWords.
  67 const size_t ParallelCompactData::Log2RegionSize  = 9; // 512 words
  68 const size_t ParallelCompactData::RegionSize      = (size_t)1 << Log2RegionSize;
  69 const size_t ParallelCompactData::RegionSizeBytes =
  70   RegionSize << LogHeapWordSize;
  71 const size_t ParallelCompactData::RegionSizeOffsetMask = RegionSize - 1;
  72 const size_t ParallelCompactData::RegionAddrOffsetMask = RegionSizeBytes - 1;
  73 const size_t ParallelCompactData::RegionAddrMask  = ~RegionAddrOffsetMask;
  74 
  75 const ParallelCompactData::RegionData::region_sz_t
  76 ParallelCompactData::RegionData::dc_shift = 27;
  77 
  78 const ParallelCompactData::RegionData::region_sz_t
  79 ParallelCompactData::RegionData::dc_mask = ~0U << dc_shift;
  80 
  81 const ParallelCompactData::RegionData::region_sz_t
  82 ParallelCompactData::RegionData::dc_one = 0x1U << dc_shift;
  83 
  84 const ParallelCompactData::RegionData::region_sz_t
  85 ParallelCompactData::RegionData::los_mask = ~dc_mask;
  86 
  87 const ParallelCompactData::RegionData::region_sz_t
  88 ParallelCompactData::RegionData::dc_claimed = 0x8U << dc_shift;
  89 
  90 const ParallelCompactData::RegionData::region_sz_t
  91 ParallelCompactData::RegionData::dc_completed = 0xcU << dc_shift;
  92 
  93 SpaceInfo PSParallelCompact::_space_info[PSParallelCompact::last_space_id];
  94 bool      PSParallelCompact::_print_phases = false;
  95 
  96 ReferenceProcessor* PSParallelCompact::_ref_processor = NULL;
  97 klassOop            PSParallelCompact::_updated_int_array_klass_obj = NULL;
  98 
  99 double PSParallelCompact::_dwl_mean;
 100 double PSParallelCompact::_dwl_std_dev;
 101 double PSParallelCompact::_dwl_first_term;
 102 double PSParallelCompact::_dwl_adjustment;
 103 #ifdef  ASSERT
 104 bool   PSParallelCompact::_dwl_initialized = false;
 105 #endif  // #ifdef ASSERT
 106 
 107 #ifdef VALIDATE_MARK_SWEEP
 108 GrowableArray<void*>*   PSParallelCompact::_root_refs_stack = NULL;
 109 GrowableArray<oop> *    PSParallelCompact::_live_oops = NULL;
 110 GrowableArray<oop> *    PSParallelCompact::_live_oops_moved_to = NULL;
 111 GrowableArray<size_t>*  PSParallelCompact::_live_oops_size = NULL;
 112 size_t                  PSParallelCompact::_live_oops_index = 0;
 113 size_t                  PSParallelCompact::_live_oops_index_at_perm = 0;
 114 GrowableArray<void*>*   PSParallelCompact::_other_refs_stack = NULL;
 115 GrowableArray<void*>*   PSParallelCompact::_adjusted_pointers = NULL;
 116 bool                    PSParallelCompact::_pointer_tracking = false;
 117 bool                    PSParallelCompact::_root_tracking = true;
 118 
 119 GrowableArray<HeapWord*>* PSParallelCompact::_cur_gc_live_oops = NULL;
 120 GrowableArray<HeapWord*>* PSParallelCompact::_cur_gc_live_oops_moved_to = NULL;
 121 GrowableArray<size_t>   * PSParallelCompact::_cur_gc_live_oops_size = NULL;
 122 GrowableArray<HeapWord*>* PSParallelCompact::_last_gc_live_oops = NULL;
 123 GrowableArray<HeapWord*>* PSParallelCompact::_last_gc_live_oops_moved_to = NULL;
 124 GrowableArray<size_t>   * PSParallelCompact::_last_gc_live_oops_size = NULL;
 125 #endif
 126 
 127 void SplitInfo::record(size_t src_region_idx, size_t partial_obj_size,
 128                        HeapWord* destination)
 129 {
 130   assert(src_region_idx != 0, "invalid src_region_idx");
 131   assert(partial_obj_size != 0, "invalid partial_obj_size argument");
 132   assert(destination != NULL, "invalid destination argument");
 133 
 134   _src_region_idx = src_region_idx;
 135   _partial_obj_size = partial_obj_size;
 136   _destination = destination;
 137 
 138   // These fields may not be updated below, so make sure they're clear.
 139   assert(_dest_region_addr == NULL, "should have been cleared");
 140   assert(_first_src_addr == NULL, "should have been cleared");
 141 
 142   // Determine the number of destination regions for the partial object.
 143   HeapWord* const last_word = destination + partial_obj_size - 1;
 144   const ParallelCompactData& sd = PSParallelCompact::summary_data();
 145   HeapWord* const beg_region_addr = sd.region_align_down(destination);
 146   HeapWord* const end_region_addr = sd.region_align_down(last_word);
 147 
 148   if (beg_region_addr == end_region_addr) {
 149     // One destination region.
 150     _destination_count = 1;
 151     if (end_region_addr == destination) {
 152       // The destination falls on a region boundary, thus the first word of the
 153       // partial object will be the first word copied to the destination region.
 154       _dest_region_addr = end_region_addr;
 155       _first_src_addr = sd.region_to_addr(src_region_idx);
 156     }
 157   } else {
 158     // Two destination regions.  When copied, the partial object will cross a
 159     // destination region boundary, so a word somewhere within the partial
 160     // object will be the first word copied to the second destination region.
 161     _destination_count = 2;
 162     _dest_region_addr = end_region_addr;
 163     const size_t ofs = pointer_delta(end_region_addr, destination);
 164     assert(ofs < _partial_obj_size, "sanity");
 165     _first_src_addr = sd.region_to_addr(src_region_idx) + ofs;
 166   }
 167 }
 168 
 169 void SplitInfo::clear()
 170 {
 171   _src_region_idx = 0;
 172   _partial_obj_size = 0;
 173   _destination = NULL;
 174   _destination_count = 0;
 175   _dest_region_addr = NULL;
 176   _first_src_addr = NULL;
 177   assert(!is_valid(), "sanity");
 178 }
 179 
 180 #ifdef  ASSERT
 181 void SplitInfo::verify_clear()
 182 {
 183   assert(_src_region_idx == 0, "not clear");
 184   assert(_partial_obj_size == 0, "not clear");
 185   assert(_destination == NULL, "not clear");
 186   assert(_destination_count == 0, "not clear");
 187   assert(_dest_region_addr == NULL, "not clear");
 188   assert(_first_src_addr == NULL, "not clear");
 189 }
 190 #endif  // #ifdef ASSERT
 191 
 192 
 193 #ifndef PRODUCT
 194 const char* PSParallelCompact::space_names[] = {
 195   "perm", "old ", "eden", "from", "to  "
 196 };
 197 
 198 void PSParallelCompact::print_region_ranges()
 199 {
 200   tty->print_cr("space  bottom     top        end        new_top");
 201   tty->print_cr("------ ---------- ---------- ---------- ----------");
 202 
 203   for (unsigned int id = 0; id < last_space_id; ++id) {
 204     const MutableSpace* space = _space_info[id].space();
 205     tty->print_cr("%u %s "
 206                   SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " "
 207                   SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " ",
 208                   id, space_names[id],
 209                   summary_data().addr_to_region_idx(space->bottom()),
 210                   summary_data().addr_to_region_idx(space->top()),
 211                   summary_data().addr_to_region_idx(space->end()),
 212                   summary_data().addr_to_region_idx(_space_info[id].new_top()));
 213   }
 214 }
 215 
 216 void
 217 print_generic_summary_region(size_t i, const ParallelCompactData::RegionData* c)
 218 {
 219 #define REGION_IDX_FORMAT        SIZE_FORMAT_W(7)
 220 #define REGION_DATA_FORMAT       SIZE_FORMAT_W(5)
 221 
 222   ParallelCompactData& sd = PSParallelCompact::summary_data();
 223   size_t dci = c->destination() ? sd.addr_to_region_idx(c->destination()) : 0;
 224   tty->print_cr(REGION_IDX_FORMAT " " PTR_FORMAT " "
 225                 REGION_IDX_FORMAT " " PTR_FORMAT " "
 226                 REGION_DATA_FORMAT " " REGION_DATA_FORMAT " "
 227                 REGION_DATA_FORMAT " " REGION_IDX_FORMAT " %d",
 228                 i, c->data_location(), dci, c->destination(),
 229                 c->partial_obj_size(), c->live_obj_size(),
 230                 c->data_size(), c->source_region(), c->destination_count());
 231 
 232 #undef  REGION_IDX_FORMAT
 233 #undef  REGION_DATA_FORMAT
 234 }
 235 
 236 void
 237 print_generic_summary_data(ParallelCompactData& summary_data,
 238                            HeapWord* const beg_addr,
 239                            HeapWord* const end_addr)
 240 {
 241   size_t total_words = 0;
 242   size_t i = summary_data.addr_to_region_idx(beg_addr);
 243   const size_t last = summary_data.addr_to_region_idx(end_addr);
 244   HeapWord* pdest = 0;
 245 
 246   while (i <= last) {
 247     ParallelCompactData::RegionData* c = summary_data.region(i);
 248     if (c->data_size() != 0 || c->destination() != pdest) {
 249       print_generic_summary_region(i, c);
 250       total_words += c->data_size();
 251       pdest = c->destination();
 252     }
 253     ++i;
 254   }
 255 
 256   tty->print_cr("summary_data_bytes=" SIZE_FORMAT, total_words * HeapWordSize);
 257 }
 258 
 259 void
 260 print_generic_summary_data(ParallelCompactData& summary_data,
 261                            SpaceInfo* space_info)
 262 {
 263   for (unsigned int id = 0; id < PSParallelCompact::last_space_id; ++id) {
 264     const MutableSpace* space = space_info[id].space();
 265     print_generic_summary_data(summary_data, space->bottom(),
 266                                MAX2(space->top(), space_info[id].new_top()));
 267   }
 268 }
 269 
 270 void
 271 print_initial_summary_region(size_t i,
 272                              const ParallelCompactData::RegionData* c,
 273                              bool newline = true)
 274 {
 275   tty->print(SIZE_FORMAT_W(5) " " PTR_FORMAT " "
 276              SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " "
 277              SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d",
 278              i, c->destination(),
 279              c->partial_obj_size(), c->live_obj_size(),
 280              c->data_size(), c->source_region(), c->destination_count());
 281   if (newline) tty->cr();
 282 }
 283 
 284 void
 285 print_initial_summary_data(ParallelCompactData& summary_data,
 286                            const MutableSpace* space) {
 287   if (space->top() == space->bottom()) {
 288     return;
 289   }
 290 
 291   const size_t region_size = ParallelCompactData::RegionSize;
 292   typedef ParallelCompactData::RegionData RegionData;
 293   HeapWord* const top_aligned_up = summary_data.region_align_up(space->top());
 294   const size_t end_region = summary_data.addr_to_region_idx(top_aligned_up);
 295   const RegionData* c = summary_data.region(end_region - 1);
 296   HeapWord* end_addr = c->destination() + c->data_size();
 297   const size_t live_in_space = pointer_delta(end_addr, space->bottom());
 298 
 299   // Print (and count) the full regions at the beginning of the space.
 300   size_t full_region_count = 0;
 301   size_t i = summary_data.addr_to_region_idx(space->bottom());
 302   while (i < end_region && summary_data.region(i)->data_size() == region_size) {
 303     print_initial_summary_region(i, summary_data.region(i));
 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     print_initial_summary_region(i, c, false);
 333     tty->print_cr(" %12.10f " SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10),
 334                   reclaimed_ratio, dead_to_right, live_to_right);
 335 
 336     live_to_right -= c->data_size();
 337     ++i;
 338   }
 339 
 340   // Any remaining regions are empty.  Print one more if there is one.
 341   if (i < end_region) {
 342     print_initial_summary_region(i, summary_data.region(i));
 343   }
 344 
 345   tty->print_cr("max:  " SIZE_FORMAT_W(4) " d2r=" SIZE_FORMAT_W(10) " "
 346                 "l2r=" SIZE_FORMAT_W(10) " max_ratio=%14.12f",
 347                 max_reclaimed_ratio_region, max_dead_to_right,
 348                 max_live_to_right, max_reclaimed_ratio);
 349 }
 350 
 351 void
 352 print_initial_summary_data(ParallelCompactData& summary_data,
 353                            SpaceInfo* space_info) {
 354   unsigned int id = PSParallelCompact::perm_space_id;
 355   const MutableSpace* space;
 356   do {
 357     space = space_info[id].space();
 358     print_initial_summary_data(summary_data, space);
 359   } while (++id < PSParallelCompact::eden_space_id);
 360 
 361   do {
 362     space = space_info[id].space();
 363     print_generic_summary_data(summary_data, space->bottom(), space->top());
 364   } while (++id < PSParallelCompact::last_space_id);
 365 }
 366 #endif  // #ifndef PRODUCT
 367 
 368 #ifdef  ASSERT
 369 size_t add_obj_count;
 370 size_t add_obj_size;
 371 size_t mark_bitmap_count;
 372 size_t mark_bitmap_size;
 373 #endif  // #ifdef ASSERT
 374 
 375 ParallelCompactData::ParallelCompactData()
 376 {
 377   _region_start = 0;
 378 
 379   _region_vspace = 0;
 380   _region_data = 0;
 381   _region_count = 0;
 382 }
 383 
 384 bool ParallelCompactData::initialize(MemRegion covered_region)
 385 {
 386   _region_start = covered_region.start();
 387   const size_t region_size = covered_region.word_size();
 388   DEBUG_ONLY(_region_end = _region_start + region_size;)
 389 
 390   assert(region_align_down(_region_start) == _region_start,
 391          "region start not aligned");
 392   assert((region_size & RegionSizeOffsetMask) == 0,
 393          "region size not a multiple of RegionSize");
 394 
 395   bool result = initialize_region_data(region_size);
 396 
 397   return result;
 398 }
 399 
 400 PSVirtualSpace*
 401 ParallelCompactData::create_vspace(size_t count, size_t element_size)
 402 {
 403   const size_t raw_bytes = count * element_size;
 404   const size_t page_sz = os::page_size_for_region(raw_bytes, raw_bytes, 10);
 405   const size_t granularity = os::vm_allocation_granularity();
 406   const size_t bytes = align_size_up(raw_bytes, MAX2(page_sz, granularity));
 407 
 408   const size_t rs_align = page_sz == (size_t) os::vm_page_size() ? 0 :
 409     MAX2(page_sz, granularity);
 410   ReservedSpace rs(bytes, rs_align, rs_align > 0);
 411   os::trace_page_sizes("par compact", raw_bytes, raw_bytes, page_sz, rs.base(),
 412                        rs.size());
 413 
 414   MemTracker::record_virtual_memory_type((address)rs.base(), mtGC);
 415 
 416   PSVirtualSpace* vspace = new PSVirtualSpace(rs, page_sz);
 417   if (vspace != 0) {
 418     if (vspace->expand_by(bytes)) {
 419       return vspace;
 420     }
 421     delete vspace;
 422     // Release memory reserved in the space.
 423     rs.release();
 424   }
 425 
 426   return 0;
 427 }
 428 
 429 bool ParallelCompactData::initialize_region_data(size_t region_size)
 430 {
 431   const size_t count = (region_size + RegionSizeOffsetMask) >> Log2RegionSize;
 432   _region_vspace = create_vspace(count, sizeof(RegionData));
 433   if (_region_vspace != 0) {
 434     _region_data = (RegionData*)_region_vspace->reserved_low_addr();
 435     _region_count = count;
 436     return true;
 437   }
 438   return false;
 439 }
 440 
 441 void ParallelCompactData::clear()
 442 {
 443   memset(_region_data, 0, _region_vspace->committed_size());
 444 }
 445 
 446 void ParallelCompactData::clear_range(size_t beg_region, size_t end_region) {
 447   assert(beg_region <= _region_count, "beg_region out of range");
 448   assert(end_region <= _region_count, "end_region out of range");
 449 
 450   const size_t region_cnt = end_region - beg_region;
 451   memset(_region_data + beg_region, 0, region_cnt * sizeof(RegionData));
 452 }
 453 
 454 HeapWord* ParallelCompactData::partial_obj_end(size_t region_idx) const
 455 {
 456   const RegionData* cur_cp = region(region_idx);
 457   const RegionData* const end_cp = region(region_count() - 1);
 458 
 459   HeapWord* result = region_to_addr(region_idx);
 460   if (cur_cp < end_cp) {
 461     do {
 462       result += cur_cp->partial_obj_size();
 463     } while (cur_cp->partial_obj_size() == RegionSize && ++cur_cp < end_cp);
 464   }
 465   return result;
 466 }
 467 
 468 void ParallelCompactData::add_obj(HeapWord* addr, size_t len)
 469 {
 470   const size_t obj_ofs = pointer_delta(addr, _region_start);
 471   const size_t beg_region = obj_ofs >> Log2RegionSize;
 472   const size_t end_region = (obj_ofs + len - 1) >> Log2RegionSize;
 473 
 474   DEBUG_ONLY(Atomic::inc_ptr(&add_obj_count);)
 475   DEBUG_ONLY(Atomic::add_ptr(len, &add_obj_size);)
 476 
 477   if (beg_region == end_region) {
 478     // All in one region.
 479     _region_data[beg_region].add_live_obj(len);
 480     return;
 481   }
 482 
 483   // First region.
 484   const size_t beg_ofs = region_offset(addr);
 485   _region_data[beg_region].add_live_obj(RegionSize - beg_ofs);
 486 
 487   klassOop klass = ((oop)addr)->klass();
 488   // Middle regions--completely spanned by this object.
 489   for (size_t region = beg_region + 1; region < end_region; ++region) {
 490     _region_data[region].set_partial_obj_size(RegionSize);
 491     _region_data[region].set_partial_obj_addr(addr);
 492   }
 493 
 494   // Last region.
 495   const size_t end_ofs = region_offset(addr + len - 1);
 496   _region_data[end_region].set_partial_obj_size(end_ofs + 1);
 497   _region_data[end_region].set_partial_obj_addr(addr);
 498 }
 499 
 500 void
 501 ParallelCompactData::summarize_dense_prefix(HeapWord* beg, HeapWord* end)
 502 {
 503   assert(region_offset(beg) == 0, "not RegionSize aligned");
 504   assert(region_offset(end) == 0, "not RegionSize aligned");
 505 
 506   size_t cur_region = addr_to_region_idx(beg);
 507   const size_t end_region = addr_to_region_idx(end);
 508   HeapWord* addr = beg;
 509   while (cur_region < end_region) {
 510     _region_data[cur_region].set_destination(addr);
 511     _region_data[cur_region].set_destination_count(0);
 512     _region_data[cur_region].set_source_region(cur_region);
 513     _region_data[cur_region].set_data_location(addr);
 514 
 515     // Update live_obj_size so the region appears completely full.
 516     size_t live_size = RegionSize - _region_data[cur_region].partial_obj_size();
 517     _region_data[cur_region].set_live_obj_size(live_size);
 518 
 519     ++cur_region;
 520     addr += RegionSize;
 521   }
 522 }
 523 
 524 // Find the point at which a space can be split and, if necessary, record the
 525 // split point.
 526 //
 527 // If the current src region (which overflowed the destination space) doesn't
 528 // have a partial object, the split point is at the beginning of the current src
 529 // region (an "easy" split, no extra bookkeeping required).
 530 //
 531 // If the current src region has a partial object, the split point is in the
 532 // region where that partial object starts (call it the split_region).  If
 533 // split_region has a partial object, then the split point is just after that
 534 // partial object (a "hard" split where we have to record the split data and
 535 // zero the partial_obj_size field).  With a "hard" split, we know that the
 536 // partial_obj ends within split_region because the partial object that caused
 537 // the overflow starts in split_region.  If split_region doesn't have a partial
 538 // obj, then the split is at the beginning of split_region (another "easy"
 539 // split).
 540 HeapWord*
 541 ParallelCompactData::summarize_split_space(size_t src_region,
 542                                            SplitInfo& split_info,
 543                                            HeapWord* destination,
 544                                            HeapWord* target_end,
 545                                            HeapWord** target_next)
 546 {
 547   assert(destination <= target_end, "sanity");
 548   assert(destination + _region_data[src_region].data_size() > target_end,
 549     "region should not fit into target space");
 550   assert(is_region_aligned(target_end), "sanity");
 551 
 552   size_t split_region = src_region;
 553   HeapWord* split_destination = destination;
 554   size_t partial_obj_size = _region_data[src_region].partial_obj_size();
 555 
 556   if (destination + partial_obj_size > target_end) {
 557     // The split point is just after the partial object (if any) in the
 558     // src_region that contains the start of the object that overflowed the
 559     // destination space.
 560     //
 561     // Find the start of the "overflow" object and set split_region to the
 562     // region containing it.
 563     HeapWord* const overflow_obj = _region_data[src_region].partial_obj_addr();
 564     split_region = addr_to_region_idx(overflow_obj);
 565 
 566     // Clear the source_region field of all destination regions whose first word
 567     // came from data after the split point (a non-null source_region field
 568     // implies a region must be filled).
 569     //
 570     // An alternative to the simple loop below:  clear during post_compact(),
 571     // which uses memcpy instead of individual stores, and is easy to
 572     // parallelize.  (The downside is that it clears the entire RegionData
 573     // object as opposed to just one field.)
 574     //
 575     // post_compact() would have to clear the summary data up to the highest
 576     // address that was written during the summary phase, which would be
 577     //
 578     //         max(top, max(new_top, clear_top))
 579     //
 580     // where clear_top is a new field in SpaceInfo.  Would have to set clear_top
 581     // to target_end.
 582     const RegionData* const sr = region(split_region);
 583     const size_t beg_idx =
 584       addr_to_region_idx(region_align_up(sr->destination() +
 585                                          sr->partial_obj_size()));
 586     const size_t end_idx = addr_to_region_idx(target_end);
 587 
 588     if (TraceParallelOldGCSummaryPhase) {
 589         gclog_or_tty->print_cr("split:  clearing source_region field in ["
 590                                SIZE_FORMAT ", " SIZE_FORMAT ")",
 591                                beg_idx, end_idx);
 592     }
 593     for (size_t idx = beg_idx; idx < end_idx; ++idx) {
 594       _region_data[idx].set_source_region(0);
 595     }
 596 
 597     // Set split_destination and partial_obj_size to reflect the split region.
 598     split_destination = sr->destination();
 599     partial_obj_size = sr->partial_obj_size();
 600   }
 601 
 602   // The split is recorded only if a partial object extends onto the region.
 603   if (partial_obj_size != 0) {
 604     _region_data[split_region].set_partial_obj_size(0);
 605     split_info.record(split_region, partial_obj_size, split_destination);
 606   }
 607 
 608   // Setup the continuation addresses.
 609   *target_next = split_destination + partial_obj_size;
 610   HeapWord* const source_next = region_to_addr(split_region) + partial_obj_size;
 611 
 612   if (TraceParallelOldGCSummaryPhase) {
 613     const char * split_type = partial_obj_size == 0 ? "easy" : "hard";
 614     gclog_or_tty->print_cr("%s split:  src=" PTR_FORMAT " src_c=" SIZE_FORMAT
 615                            " pos=" SIZE_FORMAT,
 616                            split_type, source_next, split_region,
 617                            partial_obj_size);
 618     gclog_or_tty->print_cr("%s split:  dst=" PTR_FORMAT " dst_c=" SIZE_FORMAT
 619                            " tn=" PTR_FORMAT,
 620                            split_type, split_destination,
 621                            addr_to_region_idx(split_destination),
 622                            *target_next);
 623 
 624     if (partial_obj_size != 0) {
 625       HeapWord* const po_beg = split_info.destination();
 626       HeapWord* const po_end = po_beg + split_info.partial_obj_size();
 627       gclog_or_tty->print_cr("%s split:  "
 628                              "po_beg=" PTR_FORMAT " " SIZE_FORMAT " "
 629                              "po_end=" PTR_FORMAT " " SIZE_FORMAT,
 630                              split_type,
 631                              po_beg, addr_to_region_idx(po_beg),
 632                              po_end, addr_to_region_idx(po_end));
 633     }
 634   }
 635 
 636   return source_next;
 637 }
 638 
 639 bool ParallelCompactData::summarize(SplitInfo& split_info,
 640                                     HeapWord* source_beg, HeapWord* source_end,
 641                                     HeapWord** source_next,
 642                                     HeapWord* target_beg, HeapWord* target_end,
 643                                     HeapWord** target_next)
 644 {
 645   if (TraceParallelOldGCSummaryPhase) {
 646     HeapWord* const source_next_val = source_next == NULL ? NULL : *source_next;
 647     tty->print_cr("sb=" PTR_FORMAT " se=" PTR_FORMAT " sn=" PTR_FORMAT
 648                   "tb=" PTR_FORMAT " te=" PTR_FORMAT " tn=" PTR_FORMAT,
 649                   source_beg, source_end, source_next_val,
 650                   target_beg, target_end, *target_next);
 651   }
 652 
 653   size_t cur_region = addr_to_region_idx(source_beg);
 654   const size_t end_region = addr_to_region_idx(region_align_up(source_end));
 655 
 656   HeapWord *dest_addr = target_beg;
 657   while (cur_region < end_region) {
 658     // The destination must be set even if the region has no data.
 659     _region_data[cur_region].set_destination(dest_addr);
 660 
 661     size_t words = _region_data[cur_region].data_size();
 662     if (words > 0) {
 663       // If cur_region does not fit entirely into the target space, find a point
 664       // at which the source space can be 'split' so that part is copied to the
 665       // target space and the rest is copied elsewhere.
 666       if (dest_addr + words > target_end) {
 667         assert(source_next != NULL, "source_next is NULL when splitting");
 668         *source_next = summarize_split_space(cur_region, split_info, dest_addr,
 669                                              target_end, target_next);
 670         return false;
 671       }
 672 
 673       // Compute the destination_count for cur_region, and if necessary, update
 674       // source_region for a destination region.  The source_region field is
 675       // updated if cur_region is the first (left-most) region to be copied to a
 676       // destination region.
 677       //
 678       // The destination_count calculation is a bit subtle.  A region that has
 679       // data that compacts into itself does not count itself as a destination.
 680       // This maintains the invariant that a zero count means the region is
 681       // available and can be claimed and then filled.
 682       uint destination_count = 0;
 683       if (split_info.is_split(cur_region)) {
 684         // The current region has been split:  the partial object will be copied
 685         // to one destination space and the remaining data will be copied to
 686         // another destination space.  Adjust the initial destination_count and,
 687         // if necessary, set the source_region field if the partial object will
 688         // cross a destination region boundary.
 689         destination_count = split_info.destination_count();
 690         if (destination_count == 2) {
 691           size_t dest_idx = addr_to_region_idx(split_info.dest_region_addr());
 692           _region_data[dest_idx].set_source_region(cur_region);
 693         }
 694       }
 695 
 696       HeapWord* const last_addr = dest_addr + words - 1;
 697       const size_t dest_region_1 = addr_to_region_idx(dest_addr);
 698       const size_t dest_region_2 = addr_to_region_idx(last_addr);
 699 
 700       // Initially assume that the destination regions will be the same and
 701       // adjust the value below if necessary.  Under this assumption, if
 702       // cur_region == dest_region_2, then cur_region will be compacted
 703       // completely into itself.
 704       destination_count += cur_region == dest_region_2 ? 0 : 1;
 705       if (dest_region_1 != dest_region_2) {
 706         // Destination regions differ; adjust destination_count.
 707         destination_count += 1;
 708         // Data from cur_region will be copied to the start of dest_region_2.
 709         _region_data[dest_region_2].set_source_region(cur_region);
 710       } else if (region_offset(dest_addr) == 0) {
 711         // Data from cur_region will be copied to the start of the destination
 712         // region.
 713         _region_data[dest_region_1].set_source_region(cur_region);
 714       }
 715 
 716       _region_data[cur_region].set_destination_count(destination_count);
 717       _region_data[cur_region].set_data_location(region_to_addr(cur_region));
 718       dest_addr += words;
 719     }
 720 
 721     ++cur_region;
 722   }
 723 
 724   *target_next = dest_addr;
 725   return true;
 726 }
 727 
 728 HeapWord* ParallelCompactData::calc_new_pointer(HeapWord* addr) {
 729   assert(addr != NULL, "Should detect NULL oop earlier");
 730   assert(PSParallelCompact::gc_heap()->is_in(addr), "addr not in heap");
 731 #ifdef ASSERT
 732   if (PSParallelCompact::mark_bitmap()->is_unmarked(addr)) {
 733     gclog_or_tty->print_cr("calc_new_pointer:: addr " PTR_FORMAT, addr);
 734   }
 735 #endif
 736   assert(PSParallelCompact::mark_bitmap()->is_marked(addr), "obj not marked");
 737 
 738   // Region covering the object.
 739   size_t region_index = addr_to_region_idx(addr);
 740   const RegionData* const region_ptr = region(region_index);
 741   HeapWord* const region_addr = region_align_down(addr);
 742 
 743   assert(addr < region_addr + RegionSize, "Region does not cover object");
 744   assert(addr_to_region_ptr(region_addr) == region_ptr, "sanity check");
 745 
 746   HeapWord* result = region_ptr->destination();
 747 
 748   // If all the data in the region is live, then the new location of the object
 749   // can be calculated from the destination of the region plus the offset of the
 750   // object in the region.
 751   if (region_ptr->data_size() == RegionSize) {
 752     result += pointer_delta(addr, region_addr);
 753     DEBUG_ONLY(PSParallelCompact::check_new_location(addr, result);)
 754     return result;
 755   }
 756 
 757   // The new location of the object is
 758   //    region destination +
 759   //    size of the partial object extending onto the region +
 760   //    sizes of the live objects in the Region that are to the left of addr
 761   const size_t partial_obj_size = region_ptr->partial_obj_size();
 762   HeapWord* const search_start = region_addr + partial_obj_size;
 763 
 764   const ParMarkBitMap* bitmap = PSParallelCompact::mark_bitmap();
 765   size_t live_to_left = bitmap->live_words_in_range(search_start, oop(addr));
 766 
 767   result += partial_obj_size + live_to_left;
 768   DEBUG_ONLY(PSParallelCompact::check_new_location(addr, result);)
 769   return result;
 770 }
 771 
 772 klassOop ParallelCompactData::calc_new_klass(klassOop old_klass) {
 773   klassOop updated_klass;
 774   if (PSParallelCompact::should_update_klass(old_klass)) {
 775     updated_klass = (klassOop) calc_new_pointer(old_klass);
 776   } else {
 777     updated_klass = old_klass;
 778   }
 779 
 780   return updated_klass;
 781 }
 782 
 783 #ifdef  ASSERT
 784 void ParallelCompactData::verify_clear(const PSVirtualSpace* vspace)
 785 {
 786   const size_t* const beg = (const size_t*)vspace->committed_low_addr();
 787   const size_t* const end = (const size_t*)vspace->committed_high_addr();
 788   for (const size_t* p = beg; p < end; ++p) {
 789     assert(*p == 0, "not zero");
 790   }
 791 }
 792 
 793 void ParallelCompactData::verify_clear()
 794 {
 795   verify_clear(_region_vspace);
 796 }
 797 #endif  // #ifdef ASSERT
 798 
 799 #ifdef NOT_PRODUCT
 800 ParallelCompactData::RegionData* debug_region(size_t region_index) {
 801   ParallelCompactData& sd = PSParallelCompact::summary_data();
 802   return sd.region(region_index);
 803 }
 804 #endif
 805 
 806 STWGCTimer          PSParallelCompact::_gc_timer;
 807 ParallelOldTracer   PSParallelCompact::_gc_tracer;
 808 elapsedTimer        PSParallelCompact::_accumulated_time;
 809 unsigned int        PSParallelCompact::_total_invocations = 0;
 810 unsigned int        PSParallelCompact::_maximum_compaction_gc_num = 0;
 811 jlong               PSParallelCompact::_time_of_last_gc = 0;
 812 CollectorCounters*  PSParallelCompact::_counters = NULL;
 813 ParMarkBitMap       PSParallelCompact::_mark_bitmap;
 814 ParallelCompactData PSParallelCompact::_summary_data;
 815 
 816 PSParallelCompact::IsAliveClosure PSParallelCompact::_is_alive_closure;
 817 
 818 void PSParallelCompact::IsAliveClosure::do_object(oop p)   { ShouldNotReachHere(); }
 819 bool PSParallelCompact::IsAliveClosure::do_object_b(oop p) { return mark_bitmap()->is_marked(p); }
 820 
 821 void PSParallelCompact::KeepAliveClosure::do_oop(oop* p)       { PSParallelCompact::KeepAliveClosure::do_oop_work(p); }
 822 void PSParallelCompact::KeepAliveClosure::do_oop(narrowOop* p) { PSParallelCompact::KeepAliveClosure::do_oop_work(p); }
 823 
 824 PSParallelCompact::AdjustPointerClosure PSParallelCompact::_adjust_root_pointer_closure(true);
 825 PSParallelCompact::AdjustPointerClosure PSParallelCompact::_adjust_pointer_closure(false);
 826 
 827 void PSParallelCompact::AdjustPointerClosure::do_oop(oop* p)       { adjust_pointer(p, _is_root); }
 828 void PSParallelCompact::AdjustPointerClosure::do_oop(narrowOop* p) { adjust_pointer(p, _is_root); }
 829 
 830 void PSParallelCompact::FollowStackClosure::do_void() { _compaction_manager->follow_marking_stacks(); }
 831 
 832 void PSParallelCompact::MarkAndPushClosure::do_oop(oop* p)       { mark_and_push(_compaction_manager, p); }
 833 void PSParallelCompact::MarkAndPushClosure::do_oop(narrowOop* p) { mark_and_push(_compaction_manager, p); }
 834 
 835 void PSParallelCompact::post_initialize() {
 836   ParallelScavengeHeap* heap = gc_heap();
 837   assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
 838 
 839   MemRegion mr = heap->reserved_region();
 840   _ref_processor =
 841     new ReferenceProcessor(mr,            // span
 842                            ParallelRefProcEnabled && (ParallelGCThreads > 1), // mt processing
 843                            (int) ParallelGCThreads, // mt processing degree
 844                            true,          // mt discovery
 845                            (int) ParallelGCThreads, // mt discovery degree
 846                            true,          // atomic_discovery
 847                            &_is_alive_closure, // non-header is alive closure
 848                            false);        // write barrier for next field updates
 849   _counters = new CollectorCounters("PSParallelCompact", 1);
 850 
 851   // Initialize static fields in ParCompactionManager.
 852   ParCompactionManager::initialize(mark_bitmap());
 853 }
 854 
 855 bool PSParallelCompact::initialize() {
 856   ParallelScavengeHeap* heap = gc_heap();
 857   assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
 858   MemRegion mr = heap->reserved_region();
 859 
 860   // Was the old gen get allocated successfully?
 861   if (!heap->old_gen()->is_allocated()) {
 862     return false;
 863   }
 864 
 865   initialize_space_info();
 866   initialize_dead_wood_limiter();
 867 
 868   if (!_mark_bitmap.initialize(mr)) {
 869     vm_shutdown_during_initialization("Unable to allocate bit map for "
 870       "parallel garbage collection for the requested heap size.");
 871     return false;
 872   }
 873 
 874   if (!_summary_data.initialize(mr)) {
 875     vm_shutdown_during_initialization("Unable to allocate tables for "
 876       "parallel garbage collection for the requested heap size.");
 877     return false;
 878   }
 879 
 880   return true;
 881 }
 882 
 883 void PSParallelCompact::initialize_space_info()
 884 {
 885   memset(&_space_info, 0, sizeof(_space_info));
 886 
 887   ParallelScavengeHeap* heap = gc_heap();
 888   PSYoungGen* young_gen = heap->young_gen();
 889   MutableSpace* perm_space = heap->perm_gen()->object_space();
 890 
 891   _space_info[perm_space_id].set_space(perm_space);
 892   _space_info[old_space_id].set_space(heap->old_gen()->object_space());
 893   _space_info[eden_space_id].set_space(young_gen->eden_space());
 894   _space_info[from_space_id].set_space(young_gen->from_space());
 895   _space_info[to_space_id].set_space(young_gen->to_space());
 896 
 897   _space_info[perm_space_id].set_start_array(heap->perm_gen()->start_array());
 898   _space_info[old_space_id].set_start_array(heap->old_gen()->start_array());
 899 
 900   _space_info[perm_space_id].set_min_dense_prefix(perm_space->top());
 901   if (TraceParallelOldGCDensePrefix) {
 902     tty->print_cr("perm min_dense_prefix=" PTR_FORMAT,
 903                   _space_info[perm_space_id].min_dense_prefix());
 904   }
 905 }
 906 
 907 void PSParallelCompact::initialize_dead_wood_limiter()
 908 {
 909   const size_t max = 100;
 910   _dwl_mean = double(MIN2(ParallelOldDeadWoodLimiterMean, max)) / 100.0;
 911   _dwl_std_dev = double(MIN2(ParallelOldDeadWoodLimiterStdDev, max)) / 100.0;
 912   _dwl_first_term = 1.0 / (sqrt(2.0 * M_PI) * _dwl_std_dev);
 913   DEBUG_ONLY(_dwl_initialized = true;)
 914   _dwl_adjustment = normal_distribution(1.0);
 915 }
 916 
 917 // Simple class for storing info about the heap at the start of GC, to be used
 918 // after GC for comparison/printing.
 919 class PreGCValues {
 920 public:
 921   PreGCValues() { }
 922   PreGCValues(ParallelScavengeHeap* heap) { fill(heap); }
 923 
 924   void fill(ParallelScavengeHeap* heap) {
 925     _heap_used      = heap->used();
 926     _young_gen_used = heap->young_gen()->used_in_bytes();
 927     _old_gen_used   = heap->old_gen()->used_in_bytes();
 928     _perm_gen_used  = heap->perm_gen()->used_in_bytes();
 929   };
 930 
 931   size_t heap_used() const      { return _heap_used; }
 932   size_t young_gen_used() const { return _young_gen_used; }
 933   size_t old_gen_used() const   { return _old_gen_used; }
 934   size_t perm_gen_used() const  { return _perm_gen_used; }
 935 
 936 private:
 937   size_t _heap_used;
 938   size_t _young_gen_used;
 939   size_t _old_gen_used;
 940   size_t _perm_gen_used;
 941 };
 942 
 943 void
 944 PSParallelCompact::clear_data_covering_space(SpaceId id)
 945 {
 946   // At this point, top is the value before GC, new_top() is the value that will
 947   // be set at the end of GC.  The marking bitmap is cleared to top; nothing
 948   // should be marked above top.  The summary data is cleared to the larger of
 949   // top & new_top.
 950   MutableSpace* const space = _space_info[id].space();
 951   HeapWord* const bot = space->bottom();
 952   HeapWord* const top = space->top();
 953   HeapWord* const max_top = MAX2(top, _space_info[id].new_top());
 954 
 955   const idx_t beg_bit = _mark_bitmap.addr_to_bit(bot);
 956   const idx_t end_bit = BitMap::word_align_up(_mark_bitmap.addr_to_bit(top));
 957   _mark_bitmap.clear_range(beg_bit, end_bit);
 958 
 959   const size_t beg_region = _summary_data.addr_to_region_idx(bot);
 960   const size_t end_region =
 961     _summary_data.addr_to_region_idx(_summary_data.region_align_up(max_top));
 962   _summary_data.clear_range(beg_region, end_region);
 963 
 964   // Clear the data used to 'split' regions.
 965   SplitInfo& split_info = _space_info[id].split_info();
 966   if (split_info.is_valid()) {
 967     split_info.clear();
 968   }
 969   DEBUG_ONLY(split_info.verify_clear();)
 970 }
 971 
 972 void PSParallelCompact::pre_compact(PreGCValues* pre_gc_values)
 973 {
 974   // Update the from & to space pointers in space_info, since they are swapped
 975   // at each young gen gc.  Do the update unconditionally (even though a
 976   // promotion failure does not swap spaces) because an unknown number of minor
 977   // collections will have swapped the spaces an unknown number of times.
 978   GCTraceTime tm("pre compact", print_phases(), true, &_gc_timer);
 979   ParallelScavengeHeap* heap = gc_heap();
 980   _space_info[from_space_id].set_space(heap->young_gen()->from_space());
 981   _space_info[to_space_id].set_space(heap->young_gen()->to_space());
 982 
 983   pre_gc_values->fill(heap);
 984 
 985   ParCompactionManager::reset();
 986   NOT_PRODUCT(_mark_bitmap.reset_counters());
 987   DEBUG_ONLY(add_obj_count = add_obj_size = 0;)
 988   DEBUG_ONLY(mark_bitmap_count = mark_bitmap_size = 0;)
 989 
 990   // Increment the invocation count
 991   heap->increment_total_collections(true);
 992 
 993   // We need to track unique mark sweep invocations as well.
 994   _total_invocations++;
 995 
 996   heap->print_heap_before_gc();
 997   heap->trace_heap_before_gc(&_gc_tracer);
 998 
 999   // Fill in TLABs
1000   heap->accumulate_statistics_all_tlabs();
1001   heap->ensure_parsability(true);  // retire TLABs
1002 
1003   if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
1004     HandleMark hm;  // Discard invalid handles created during verification
1005     gclog_or_tty->print(" VerifyBeforeGC:");
1006     Universe::verify();
1007   }
1008 
1009   // Verify object start arrays
1010   if (VerifyObjectStartArray &&
1011       VerifyBeforeGC) {
1012     heap->old_gen()->verify_object_start_array();
1013     heap->perm_gen()->verify_object_start_array();
1014   }
1015 
1016   DEBUG_ONLY(mark_bitmap()->verify_clear();)
1017   DEBUG_ONLY(summary_data().verify_clear();)
1018 
1019   // Have worker threads release resources the next time they run a task.
1020   gc_task_manager()->release_all_resources();
1021 }
1022 
1023 void PSParallelCompact::post_compact()
1024 {
1025   GCTraceTime tm("post compact", print_phases(), true, &_gc_timer);
1026 
1027   for (unsigned int id = perm_space_id; id < last_space_id; ++id) {
1028     // Clear the marking bitmap, summary data and split info.
1029     clear_data_covering_space(SpaceId(id));
1030     // Update top().  Must be done after clearing the bitmap and summary data.
1031     _space_info[id].publish_new_top();
1032   }
1033 
1034   MutableSpace* const eden_space = _space_info[eden_space_id].space();
1035   MutableSpace* const from_space = _space_info[from_space_id].space();
1036   MutableSpace* const to_space   = _space_info[to_space_id].space();
1037 
1038   ParallelScavengeHeap* heap = gc_heap();
1039   bool eden_empty = eden_space->is_empty();
1040   if (!eden_empty) {
1041     eden_empty = absorb_live_data_from_eden(heap->size_policy(),
1042                                             heap->young_gen(), heap->old_gen());
1043   }
1044 
1045   // Update heap occupancy information which is used as input to the soft ref
1046   // clearing policy at the next gc.
1047   Universe::update_heap_info_at_gc();
1048 
1049   bool young_gen_empty = eden_empty && from_space->is_empty() &&
1050     to_space->is_empty();
1051 
1052   BarrierSet* bs = heap->barrier_set();
1053   if (bs->is_a(BarrierSet::ModRef)) {
1054     ModRefBarrierSet* modBS = (ModRefBarrierSet*)bs;
1055     MemRegion old_mr = heap->old_gen()->reserved();
1056     MemRegion perm_mr = heap->perm_gen()->reserved();
1057     assert(perm_mr.end() <= old_mr.start(), "Generations out of order");
1058 
1059     if (young_gen_empty) {
1060       modBS->clear(MemRegion(perm_mr.start(), old_mr.end()));
1061     } else {
1062       modBS->invalidate(MemRegion(perm_mr.start(), old_mr.end()));
1063     }
1064   }
1065 
1066   Threads::gc_epilogue();
1067   CodeCache::gc_epilogue();
1068   JvmtiExport::gc_epilogue();
1069 
1070   COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1071 
1072   ref_processor()->enqueue_discovered_references(NULL);
1073 
1074   if (ZapUnusedHeapArea) {
1075     heap->gen_mangle_unused_area();
1076   }
1077 
1078   // Update time of last GC
1079   reset_millis_since_last_gc();
1080 }
1081 
1082 HeapWord*
1083 PSParallelCompact::compute_dense_prefix_via_density(const SpaceId id,
1084                                                     bool maximum_compaction)
1085 {
1086   const size_t region_size = ParallelCompactData::RegionSize;
1087   const ParallelCompactData& sd = summary_data();
1088 
1089   const MutableSpace* const space = _space_info[id].space();
1090   HeapWord* const top_aligned_up = sd.region_align_up(space->top());
1091   const RegionData* const beg_cp = sd.addr_to_region_ptr(space->bottom());
1092   const RegionData* const end_cp = sd.addr_to_region_ptr(top_aligned_up);
1093 
1094   // Skip full regions at the beginning of the space--they are necessarily part
1095   // of the dense prefix.
1096   size_t full_count = 0;
1097   const RegionData* cp;
1098   for (cp = beg_cp; cp < end_cp && cp->data_size() == region_size; ++cp) {
1099     ++full_count;
1100   }
1101 
1102   assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");
1103   const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;
1104   const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval;
1105   if (maximum_compaction || cp == end_cp || interval_ended) {
1106     _maximum_compaction_gc_num = total_invocations();
1107     return sd.region_to_addr(cp);
1108   }
1109 
1110   HeapWord* const new_top = _space_info[id].new_top();
1111   const size_t space_live = pointer_delta(new_top, space->bottom());
1112   const size_t space_used = space->used_in_words();
1113   const size_t space_capacity = space->capacity_in_words();
1114 
1115   const double cur_density = double(space_live) / space_capacity;
1116   const double deadwood_density =
1117     (1.0 - cur_density) * (1.0 - cur_density) * cur_density * cur_density;
1118   const size_t deadwood_goal = size_t(space_capacity * deadwood_density);
1119 
1120   if (TraceParallelOldGCDensePrefix) {
1121     tty->print_cr("cur_dens=%5.3f dw_dens=%5.3f dw_goal=" SIZE_FORMAT,
1122                   cur_density, deadwood_density, deadwood_goal);
1123     tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " "
1124                   "space_cap=" SIZE_FORMAT,
1125                   space_live, space_used,
1126                   space_capacity);
1127   }
1128 
1129   // XXX - Use binary search?
1130   HeapWord* dense_prefix = sd.region_to_addr(cp);
1131   const RegionData* full_cp = cp;
1132   const RegionData* const top_cp = sd.addr_to_region_ptr(space->top() - 1);
1133   while (cp < end_cp) {
1134     HeapWord* region_destination = cp->destination();
1135     const size_t cur_deadwood = pointer_delta(dense_prefix, region_destination);
1136     if (TraceParallelOldGCDensePrefix && Verbose) {
1137       tty->print_cr("c#=" SIZE_FORMAT_W(4) " dst=" PTR_FORMAT " "
1138                     "dp=" SIZE_FORMAT_W(8) " " "cdw=" SIZE_FORMAT_W(8),
1139                     sd.region(cp), region_destination,
1140                     dense_prefix, cur_deadwood);
1141     }
1142 
1143     if (cur_deadwood >= deadwood_goal) {
1144       // Found the region that has the correct amount of deadwood to the left.
1145       // This typically occurs after crossing a fairly sparse set of regions, so
1146       // iterate backwards over those sparse regions, looking for the region
1147       // that has the lowest density of live objects 'to the right.'
1148       size_t space_to_left = sd.region(cp) * region_size;
1149       size_t live_to_left = space_to_left - cur_deadwood;
1150       size_t space_to_right = space_capacity - space_to_left;
1151       size_t live_to_right = space_live - live_to_left;
1152       double density_to_right = double(live_to_right) / space_to_right;
1153       while (cp > full_cp) {
1154         --cp;
1155         const size_t prev_region_live_to_right = live_to_right -
1156           cp->data_size();
1157         const size_t prev_region_space_to_right = space_to_right + region_size;
1158         double prev_region_density_to_right =
1159           double(prev_region_live_to_right) / prev_region_space_to_right;
1160         if (density_to_right <= prev_region_density_to_right) {
1161           return dense_prefix;
1162         }
1163         if (TraceParallelOldGCDensePrefix && Verbose) {
1164           tty->print_cr("backing up from c=" SIZE_FORMAT_W(4) " d2r=%10.8f "
1165                         "pc_d2r=%10.8f", sd.region(cp), density_to_right,
1166                         prev_region_density_to_right);
1167         }
1168         dense_prefix -= region_size;
1169         live_to_right = prev_region_live_to_right;
1170         space_to_right = prev_region_space_to_right;
1171         density_to_right = prev_region_density_to_right;
1172       }
1173       return dense_prefix;
1174     }
1175 
1176     dense_prefix += region_size;
1177     ++cp;
1178   }
1179 
1180   return dense_prefix;
1181 }
1182 
1183 #ifndef PRODUCT
1184 void PSParallelCompact::print_dense_prefix_stats(const char* const algorithm,
1185                                                  const SpaceId id,
1186                                                  const bool maximum_compaction,
1187                                                  HeapWord* const addr)
1188 {
1189   const size_t region_idx = summary_data().addr_to_region_idx(addr);
1190   RegionData* const cp = summary_data().region(region_idx);
1191   const MutableSpace* const space = _space_info[id].space();
1192   HeapWord* const new_top = _space_info[id].new_top();
1193 
1194   const size_t space_live = pointer_delta(new_top, space->bottom());
1195   const size_t dead_to_left = pointer_delta(addr, cp->destination());
1196   const size_t space_cap = space->capacity_in_words();
1197   const double dead_to_left_pct = double(dead_to_left) / space_cap;
1198   const size_t live_to_right = new_top - cp->destination();
1199   const size_t dead_to_right = space->top() - addr - live_to_right;
1200 
1201   tty->print_cr("%s=" PTR_FORMAT " dpc=" SIZE_FORMAT_W(5) " "
1202                 "spl=" SIZE_FORMAT " "
1203                 "d2l=" SIZE_FORMAT " d2l%%=%6.4f "
1204                 "d2r=" SIZE_FORMAT " l2r=" SIZE_FORMAT
1205                 " ratio=%10.8f",
1206                 algorithm, addr, region_idx,
1207                 space_live,
1208                 dead_to_left, dead_to_left_pct,
1209                 dead_to_right, live_to_right,
1210                 double(dead_to_right) / live_to_right);
1211 }
1212 #endif  // #ifndef PRODUCT
1213 
1214 // Return a fraction indicating how much of the generation can be treated as
1215 // "dead wood" (i.e., not reclaimed).  The function uses a normal distribution
1216 // based on the density of live objects in the generation to determine a limit,
1217 // which is then adjusted so the return value is min_percent when the density is
1218 // 1.
1219 //
1220 // The following table shows some return values for a different values of the
1221 // standard deviation (ParallelOldDeadWoodLimiterStdDev); the mean is 0.5 and
1222 // min_percent is 1.
1223 //
1224 //                          fraction allowed as dead wood
1225 //         -----------------------------------------------------------------
1226 // density std_dev=70 std_dev=75 std_dev=80 std_dev=85 std_dev=90 std_dev=95
1227 // ------- ---------- ---------- ---------- ---------- ---------- ----------
1228 // 0.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
1229 // 0.05000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
1230 // 0.10000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
1231 // 0.15000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
1232 // 0.20000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
1233 // 0.25000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
1234 // 0.30000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
1235 // 0.35000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
1236 // 0.40000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
1237 // 0.45000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
1238 // 0.50000 0.13832410 0.11599237 0.09847664 0.08456518 0.07338887 0.06431510
1239 // 0.55000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
1240 // 0.60000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
1241 // 0.65000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
1242 // 0.70000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
1243 // 0.75000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
1244 // 0.80000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
1245 // 0.85000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
1246 // 0.90000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
1247 // 0.95000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
1248 // 1.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
1249 
1250 double PSParallelCompact::dead_wood_limiter(double density, size_t min_percent)
1251 {
1252   assert(_dwl_initialized, "uninitialized");
1253 
1254   // The raw limit is the value of the normal distribution at x = density.
1255   const double raw_limit = normal_distribution(density);
1256 
1257   // Adjust the raw limit so it becomes the minimum when the density is 1.
1258   //
1259   // First subtract the adjustment value (which is simply the precomputed value
1260   // normal_distribution(1.0)); this yields a value of 0 when the density is 1.
1261   // Then add the minimum value, so the minimum is returned when the density is
1262   // 1.  Finally, prevent negative values, which occur when the mean is not 0.5.
1263   const double min = double(min_percent) / 100.0;
1264   const double limit = raw_limit - _dwl_adjustment + min;
1265   return MAX2(limit, 0.0);
1266 }
1267 
1268 ParallelCompactData::RegionData*
1269 PSParallelCompact::first_dead_space_region(const RegionData* beg,
1270                                            const RegionData* end)
1271 {
1272   const size_t region_size = ParallelCompactData::RegionSize;
1273   ParallelCompactData& sd = summary_data();
1274   size_t left = sd.region(beg);
1275   size_t right = end > beg ? sd.region(end) - 1 : left;
1276 
1277   // Binary search.
1278   while (left < right) {
1279     // Equivalent to (left + right) / 2, but does not overflow.
1280     const size_t middle = left + (right - left) / 2;
1281     RegionData* const middle_ptr = sd.region(middle);
1282     HeapWord* const dest = middle_ptr->destination();
1283     HeapWord* const addr = sd.region_to_addr(middle);
1284     assert(dest != NULL, "sanity");
1285     assert(dest <= addr, "must move left");
1286 
1287     if (middle > left && dest < addr) {
1288       right = middle - 1;
1289     } else if (middle < right && middle_ptr->data_size() == region_size) {
1290       left = middle + 1;
1291     } else {
1292       return middle_ptr;
1293     }
1294   }
1295   return sd.region(left);
1296 }
1297 
1298 ParallelCompactData::RegionData*
1299 PSParallelCompact::dead_wood_limit_region(const RegionData* beg,
1300                                           const RegionData* end,
1301                                           size_t dead_words)
1302 {
1303   ParallelCompactData& sd = summary_data();
1304   size_t left = sd.region(beg);
1305   size_t right = end > beg ? sd.region(end) - 1 : left;
1306 
1307   // Binary search.
1308   while (left < right) {
1309     // Equivalent to (left + right) / 2, but does not overflow.
1310     const size_t middle = left + (right - left) / 2;
1311     RegionData* const middle_ptr = sd.region(middle);
1312     HeapWord* const dest = middle_ptr->destination();
1313     HeapWord* const addr = sd.region_to_addr(middle);
1314     assert(dest != NULL, "sanity");
1315     assert(dest <= addr, "must move left");
1316 
1317     const size_t dead_to_left = pointer_delta(addr, dest);
1318     if (middle > left && dead_to_left > dead_words) {
1319       right = middle - 1;
1320     } else if (middle < right && dead_to_left < dead_words) {
1321       left = middle + 1;
1322     } else {
1323       return middle_ptr;
1324     }
1325   }
1326   return sd.region(left);
1327 }
1328 
1329 // The result is valid during the summary phase, after the initial summarization
1330 // of each space into itself, and before final summarization.
1331 inline double
1332 PSParallelCompact::reclaimed_ratio(const RegionData* const cp,
1333                                    HeapWord* const bottom,
1334                                    HeapWord* const top,
1335                                    HeapWord* const new_top)
1336 {
1337   ParallelCompactData& sd = summary_data();
1338 
1339   assert(cp != NULL, "sanity");
1340   assert(bottom != NULL, "sanity");
1341   assert(top != NULL, "sanity");
1342   assert(new_top != NULL, "sanity");
1343   assert(top >= new_top, "summary data problem?");
1344   assert(new_top > bottom, "space is empty; should not be here");
1345   assert(new_top >= cp->destination(), "sanity");
1346   assert(top >= sd.region_to_addr(cp), "sanity");
1347 
1348   HeapWord* const destination = cp->destination();
1349   const size_t dense_prefix_live  = pointer_delta(destination, bottom);
1350   const size_t compacted_region_live = pointer_delta(new_top, destination);
1351   const size_t compacted_region_used = pointer_delta(top,
1352                                                      sd.region_to_addr(cp));
1353   const size_t reclaimable = compacted_region_used - compacted_region_live;
1354 
1355   const double divisor = dense_prefix_live + 1.25 * compacted_region_live;
1356   return double(reclaimable) / divisor;
1357 }
1358 
1359 // Return the address of the end of the dense prefix, a.k.a. the start of the
1360 // compacted region.  The address is always on a region boundary.
1361 //
1362 // Completely full regions at the left are skipped, since no compaction can
1363 // occur in those regions.  Then the maximum amount of dead wood to allow is
1364 // computed, based on the density (amount live / capacity) of the generation;
1365 // the region with approximately that amount of dead space to the left is
1366 // identified as the limit region.  Regions between the last completely full
1367 // region and the limit region are scanned and the one that has the best
1368 // (maximum) reclaimed_ratio() is selected.
1369 HeapWord*
1370 PSParallelCompact::compute_dense_prefix(const SpaceId id,
1371                                         bool maximum_compaction)
1372 {
1373   if (ParallelOldGCSplitALot) {
1374     if (_space_info[id].dense_prefix() != _space_info[id].space()->bottom()) {
1375       // The value was chosen to provoke splitting a young gen space; use it.
1376       return _space_info[id].dense_prefix();
1377     }
1378   }
1379 
1380   const size_t region_size = ParallelCompactData::RegionSize;
1381   const ParallelCompactData& sd = summary_data();
1382 
1383   const MutableSpace* const space = _space_info[id].space();
1384   HeapWord* const top = space->top();
1385   HeapWord* const top_aligned_up = sd.region_align_up(top);
1386   HeapWord* const new_top = _space_info[id].new_top();
1387   HeapWord* const new_top_aligned_up = sd.region_align_up(new_top);
1388   HeapWord* const bottom = space->bottom();
1389   const RegionData* const beg_cp = sd.addr_to_region_ptr(bottom);
1390   const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
1391   const RegionData* const new_top_cp =
1392     sd.addr_to_region_ptr(new_top_aligned_up);
1393 
1394   // Skip full regions at the beginning of the space--they are necessarily part
1395   // of the dense prefix.
1396   const RegionData* const full_cp = first_dead_space_region(beg_cp, new_top_cp);
1397   assert(full_cp->destination() == sd.region_to_addr(full_cp) ||
1398          space->is_empty(), "no dead space allowed to the left");
1399   assert(full_cp->data_size() < region_size || full_cp == new_top_cp - 1,
1400          "region must have dead space");
1401 
1402   // The gc number is saved whenever a maximum compaction is done, and used to
1403   // determine when the maximum compaction interval has expired.  This avoids
1404   // successive max compactions for different reasons.
1405   assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");
1406   const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;
1407   const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval ||
1408     total_invocations() == HeapFirstMaximumCompactionCount;
1409   if (maximum_compaction || full_cp == top_cp || interval_ended) {
1410     _maximum_compaction_gc_num = total_invocations();
1411     return sd.region_to_addr(full_cp);
1412   }
1413 
1414   const size_t space_live = pointer_delta(new_top, bottom);
1415   const size_t space_used = space->used_in_words();
1416   const size_t space_capacity = space->capacity_in_words();
1417 
1418   const double density = double(space_live) / double(space_capacity);
1419   const size_t min_percent_free =
1420           id == perm_space_id ? PermMarkSweepDeadRatio : MarkSweepDeadRatio;
1421   const double limiter = dead_wood_limiter(density, min_percent_free);
1422   const size_t dead_wood_max = space_used - space_live;
1423   const size_t dead_wood_limit = MIN2(size_t(space_capacity * limiter),
1424                                       dead_wood_max);
1425 
1426   if (TraceParallelOldGCDensePrefix) {
1427     tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " "
1428                   "space_cap=" SIZE_FORMAT,
1429                   space_live, space_used,
1430                   space_capacity);
1431     tty->print_cr("dead_wood_limiter(%6.4f, %d)=%6.4f "
1432                   "dead_wood_max=" SIZE_FORMAT " dead_wood_limit=" SIZE_FORMAT,
1433                   density, min_percent_free, limiter,
1434                   dead_wood_max, dead_wood_limit);
1435   }
1436 
1437   // Locate the region with the desired amount of dead space to the left.
1438   const RegionData* const limit_cp =
1439     dead_wood_limit_region(full_cp, top_cp, dead_wood_limit);
1440 
1441   // Scan from the first region with dead space to the limit region and find the
1442   // one with the best (largest) reclaimed ratio.
1443   double best_ratio = 0.0;
1444   const RegionData* best_cp = full_cp;
1445   for (const RegionData* cp = full_cp; cp < limit_cp; ++cp) {
1446     double tmp_ratio = reclaimed_ratio(cp, bottom, top, new_top);
1447     if (tmp_ratio > best_ratio) {
1448       best_cp = cp;
1449       best_ratio = tmp_ratio;
1450     }
1451   }
1452 
1453 #if     0
1454   // Something to consider:  if the region with the best ratio is 'close to' the
1455   // first region w/free space, choose the first region with free space
1456   // ("first-free").  The first-free region is usually near the start of the
1457   // heap, which means we are copying most of the heap already, so copy a bit
1458   // more to get complete compaction.
1459   if (pointer_delta(best_cp, full_cp, sizeof(RegionData)) < 4) {
1460     _maximum_compaction_gc_num = total_invocations();
1461     best_cp = full_cp;
1462   }
1463 #endif  // #if 0
1464 
1465   return sd.region_to_addr(best_cp);
1466 }
1467 
1468 #ifndef PRODUCT
1469 void
1470 PSParallelCompact::fill_with_live_objects(SpaceId id, HeapWord* const start,
1471                                           size_t words)
1472 {
1473   if (TraceParallelOldGCSummaryPhase) {
1474     tty->print_cr("fill_with_live_objects [" PTR_FORMAT " " PTR_FORMAT ") "
1475                   SIZE_FORMAT, start, start + words, words);
1476   }
1477 
1478   ObjectStartArray* const start_array = _space_info[id].start_array();
1479   CollectedHeap::fill_with_objects(start, words);
1480   for (HeapWord* p = start; p < start + words; p += oop(p)->size()) {
1481     _mark_bitmap.mark_obj(p, words);
1482     _summary_data.add_obj(p, words);
1483     start_array->allocate_block(p);
1484   }
1485 }
1486 
1487 void
1488 PSParallelCompact::summarize_new_objects(SpaceId id, HeapWord* start)
1489 {
1490   ParallelCompactData& sd = summary_data();
1491   MutableSpace* space = _space_info[id].space();
1492 
1493   // Find the source and destination start addresses.
1494   HeapWord* const src_addr = sd.region_align_down(start);
1495   HeapWord* dst_addr;
1496   if (src_addr < start) {
1497     dst_addr = sd.addr_to_region_ptr(src_addr)->destination();
1498   } else if (src_addr > space->bottom()) {
1499     // The start (the original top() value) is aligned to a region boundary so
1500     // the associated region does not have a destination.  Compute the
1501     // destination from the previous region.
1502     RegionData* const cp = sd.addr_to_region_ptr(src_addr) - 1;
1503     dst_addr = cp->destination() + cp->data_size();
1504   } else {
1505     // Filling the entire space.
1506     dst_addr = space->bottom();
1507   }
1508   assert(dst_addr != NULL, "sanity");
1509 
1510   // Update the summary data.
1511   bool result = _summary_data.summarize(_space_info[id].split_info(),
1512                                         src_addr, space->top(), NULL,
1513                                         dst_addr, space->end(),
1514                                         _space_info[id].new_top_addr());
1515   assert(result, "should not fail:  bad filler object size");
1516 }
1517 
1518 void
1519 PSParallelCompact::provoke_split_fill_survivor(SpaceId id)
1520 {
1521   if (total_invocations() % (ParallelOldGCSplitInterval * 3) != 0) {
1522     return;
1523   }
1524 
1525   MutableSpace* const space = _space_info[id].space();
1526   if (space->is_empty()) {
1527     HeapWord* b = space->bottom();
1528     HeapWord* t = b + space->capacity_in_words() / 2;
1529     space->set_top(t);
1530     if (ZapUnusedHeapArea) {
1531       space->set_top_for_allocations();
1532     }
1533 
1534     size_t min_size = CollectedHeap::min_fill_size();
1535     size_t obj_len = min_size;
1536     while (b + obj_len <= t) {
1537       CollectedHeap::fill_with_object(b, obj_len);
1538       mark_bitmap()->mark_obj(b, obj_len);
1539       summary_data().add_obj(b, obj_len);
1540       b += obj_len;
1541       obj_len = (obj_len & (min_size*3)) + min_size; // 8 16 24 32 8 16 24 32 ...
1542     }
1543     if (b < t) {
1544       // The loop didn't completely fill to t (top); adjust top downward.
1545       space->set_top(b);
1546       if (ZapUnusedHeapArea) {
1547         space->set_top_for_allocations();
1548       }
1549     }
1550 
1551     HeapWord** nta = _space_info[id].new_top_addr();
1552     bool result = summary_data().summarize(_space_info[id].split_info(),
1553                                            space->bottom(), space->top(), NULL,
1554                                            space->bottom(), space->end(), nta);
1555     assert(result, "space must fit into itself");
1556   }
1557 }
1558 
1559 void
1560 PSParallelCompact::provoke_split(bool & max_compaction)
1561 {
1562   if (total_invocations() % ParallelOldGCSplitInterval != 0) {
1563     return;
1564   }
1565 
1566   const size_t region_size = ParallelCompactData::RegionSize;
1567   ParallelCompactData& sd = summary_data();
1568 
1569   MutableSpace* const eden_space = _space_info[eden_space_id].space();
1570   MutableSpace* const from_space = _space_info[from_space_id].space();
1571   const size_t eden_live = pointer_delta(eden_space->top(),
1572                                          _space_info[eden_space_id].new_top());
1573   const size_t from_live = pointer_delta(from_space->top(),
1574                                          _space_info[from_space_id].new_top());
1575 
1576   const size_t min_fill_size = CollectedHeap::min_fill_size();
1577   const size_t eden_free = pointer_delta(eden_space->end(), eden_space->top());
1578   const size_t eden_fillable = eden_free >= min_fill_size ? eden_free : 0;
1579   const size_t from_free = pointer_delta(from_space->end(), from_space->top());
1580   const size_t from_fillable = from_free >= min_fill_size ? from_free : 0;
1581 
1582   // Choose the space to split; need at least 2 regions live (or fillable).
1583   SpaceId id;
1584   MutableSpace* space;
1585   size_t live_words;
1586   size_t fill_words;
1587   if (eden_live + eden_fillable >= region_size * 2) {
1588     id = eden_space_id;
1589     space = eden_space;
1590     live_words = eden_live;
1591     fill_words = eden_fillable;
1592   } else if (from_live + from_fillable >= region_size * 2) {
1593     id = from_space_id;
1594     space = from_space;
1595     live_words = from_live;
1596     fill_words = from_fillable;
1597   } else {
1598     return; // Give up.
1599   }
1600   assert(fill_words == 0 || fill_words >= min_fill_size, "sanity");
1601 
1602   if (live_words < region_size * 2) {
1603     // Fill from top() to end() w/live objects of mixed sizes.
1604     HeapWord* const fill_start = space->top();
1605     live_words += fill_words;
1606 
1607     space->set_top(fill_start + fill_words);
1608     if (ZapUnusedHeapArea) {
1609       space->set_top_for_allocations();
1610     }
1611 
1612     HeapWord* cur_addr = fill_start;
1613     while (fill_words > 0) {
1614       const size_t r = (size_t)os::random() % (region_size / 2) + min_fill_size;
1615       size_t cur_size = MIN2(align_object_size_(r), fill_words);
1616       if (fill_words - cur_size < min_fill_size) {
1617         cur_size = fill_words; // Avoid leaving a fragment too small to fill.
1618       }
1619 
1620       CollectedHeap::fill_with_object(cur_addr, cur_size);
1621       mark_bitmap()->mark_obj(cur_addr, cur_size);
1622       sd.add_obj(cur_addr, cur_size);
1623 
1624       cur_addr += cur_size;
1625       fill_words -= cur_size;
1626     }
1627 
1628     summarize_new_objects(id, fill_start);
1629   }
1630 
1631   max_compaction = false;
1632 
1633   // Manipulate the old gen so that it has room for about half of the live data
1634   // in the target young gen space (live_words / 2).
1635   id = old_space_id;
1636   space = _space_info[id].space();
1637   const size_t free_at_end = space->free_in_words();
1638   const size_t free_target = align_object_size(live_words / 2);
1639   const size_t dead = pointer_delta(space->top(), _space_info[id].new_top());
1640 
1641   if (free_at_end >= free_target + min_fill_size) {
1642     // Fill space above top() and set the dense prefix so everything survives.
1643     HeapWord* const fill_start = space->top();
1644     const size_t fill_size = free_at_end - free_target;
1645     space->set_top(space->top() + fill_size);
1646     if (ZapUnusedHeapArea) {
1647       space->set_top_for_allocations();
1648     }
1649     fill_with_live_objects(id, fill_start, fill_size);
1650     summarize_new_objects(id, fill_start);
1651     _space_info[id].set_dense_prefix(sd.region_align_down(space->top()));
1652   } else if (dead + free_at_end > free_target) {
1653     // Find a dense prefix that makes the right amount of space available.
1654     HeapWord* cur = sd.region_align_down(space->top());
1655     HeapWord* cur_destination = sd.addr_to_region_ptr(cur)->destination();
1656     size_t dead_to_right = pointer_delta(space->end(), cur_destination);
1657     while (dead_to_right < free_target) {
1658       cur -= region_size;
1659       cur_destination = sd.addr_to_region_ptr(cur)->destination();
1660       dead_to_right = pointer_delta(space->end(), cur_destination);
1661     }
1662     _space_info[id].set_dense_prefix(cur);
1663   }
1664 }
1665 #endif // #ifndef PRODUCT
1666 
1667 void PSParallelCompact::summarize_spaces_quick()
1668 {
1669   for (unsigned int i = 0; i < last_space_id; ++i) {
1670     const MutableSpace* space = _space_info[i].space();
1671     HeapWord** nta = _space_info[i].new_top_addr();
1672     bool result = _summary_data.summarize(_space_info[i].split_info(),
1673                                           space->bottom(), space->top(), NULL,
1674                                           space->bottom(), space->end(), nta);
1675     assert(result, "space must fit into itself");
1676     _space_info[i].set_dense_prefix(space->bottom());
1677   }
1678 
1679 #ifndef PRODUCT
1680   if (ParallelOldGCSplitALot) {
1681     provoke_split_fill_survivor(to_space_id);
1682   }
1683 #endif // #ifndef PRODUCT
1684 }
1685 
1686 void PSParallelCompact::fill_dense_prefix_end(SpaceId id)
1687 {
1688   HeapWord* const dense_prefix_end = dense_prefix(id);
1689   const RegionData* region = _summary_data.addr_to_region_ptr(dense_prefix_end);
1690   const idx_t dense_prefix_bit = _mark_bitmap.addr_to_bit(dense_prefix_end);
1691   if (dead_space_crosses_boundary(region, dense_prefix_bit)) {
1692     // Only enough dead space is filled so that any remaining dead space to the
1693     // left is larger than the minimum filler object.  (The remainder is filled
1694     // during the copy/update phase.)
1695     //
1696     // The size of the dead space to the right of the boundary is not a
1697     // concern, since compaction will be able to use whatever space is
1698     // available.
1699     //
1700     // Here '||' is the boundary, 'x' represents a don't care bit and a box
1701     // surrounds the space to be filled with an object.
1702     //
1703     // In the 32-bit VM, each bit represents two 32-bit words:
1704     //                              +---+
1705     // a) beg_bits:  ...  x   x   x | 0 | ||   0   x  x  ...
1706     //    end_bits:  ...  x   x   x | 0 | ||   0   x  x  ...
1707     //                              +---+
1708     //
1709     // In the 64-bit VM, each bit represents one 64-bit word:
1710     //                              +------------+
1711     // b) beg_bits:  ...  x   x   x | 0   ||   0 | x  x  ...
1712     //    end_bits:  ...  x   x   1 | 0   ||   0 | x  x  ...
1713     //                              +------------+
1714     //                          +-------+
1715     // c) beg_bits:  ...  x   x | 0   0 | ||   0   x  x  ...
1716     //    end_bits:  ...  x   1 | 0   0 | ||   0   x  x  ...
1717     //                          +-------+
1718     //                      +-----------+
1719     // d) beg_bits:  ...  x | 0   0   0 | ||   0   x  x  ...
1720     //    end_bits:  ...  1 | 0   0   0 | ||   0   x  x  ...
1721     //                      +-----------+
1722     //                          +-------+
1723     // e) beg_bits:  ...  0   0 | 0   0 | ||   0   x  x  ...
1724     //    end_bits:  ...  0   0 | 0   0 | ||   0   x  x  ...
1725     //                          +-------+
1726 
1727     // Initially assume case a, c or e will apply.
1728     size_t obj_len = CollectedHeap::min_fill_size();
1729     HeapWord* obj_beg = dense_prefix_end - obj_len;
1730 
1731 #ifdef  _LP64
1732     if (MinObjAlignment > 1) { // object alignment > heap word size
1733       // Cases a, c or e.
1734     } else if (_mark_bitmap.is_obj_end(dense_prefix_bit - 2)) {
1735       // Case b above.
1736       obj_beg = dense_prefix_end - 1;
1737     } else if (!_mark_bitmap.is_obj_end(dense_prefix_bit - 3) &&
1738                _mark_bitmap.is_obj_end(dense_prefix_bit - 4)) {
1739       // Case d above.
1740       obj_beg = dense_prefix_end - 3;
1741       obj_len = 3;
1742     }
1743 #endif  // #ifdef _LP64
1744 
1745     CollectedHeap::fill_with_object(obj_beg, obj_len);
1746     _mark_bitmap.mark_obj(obj_beg, obj_len);
1747     _summary_data.add_obj(obj_beg, obj_len);
1748     assert(start_array(id) != NULL, "sanity");
1749     start_array(id)->allocate_block(obj_beg);
1750   }
1751 }
1752 
1753 void
1754 PSParallelCompact::clear_source_region(HeapWord* beg_addr, HeapWord* end_addr)
1755 {
1756   RegionData* const beg_ptr = _summary_data.addr_to_region_ptr(beg_addr);
1757   HeapWord* const end_aligned_up = _summary_data.region_align_up(end_addr);
1758   RegionData* const end_ptr = _summary_data.addr_to_region_ptr(end_aligned_up);
1759   for (RegionData* cur = beg_ptr; cur < end_ptr; ++cur) {
1760     cur->set_source_region(0);
1761   }
1762 }
1763 
1764 void
1765 PSParallelCompact::summarize_space(SpaceId id, bool maximum_compaction)
1766 {
1767   assert(id < last_space_id, "id out of range");
1768   assert(_space_info[id].dense_prefix() == _space_info[id].space()->bottom() ||
1769          ParallelOldGCSplitALot && id == old_space_id,
1770          "should have been reset in summarize_spaces_quick()");
1771 
1772   const MutableSpace* space = _space_info[id].space();
1773   if (_space_info[id].new_top() != space->bottom()) {
1774     HeapWord* dense_prefix_end = compute_dense_prefix(id, maximum_compaction);
1775     _space_info[id].set_dense_prefix(dense_prefix_end);
1776 
1777 #ifndef PRODUCT
1778     if (TraceParallelOldGCDensePrefix) {
1779       print_dense_prefix_stats("ratio", id, maximum_compaction,
1780                                dense_prefix_end);
1781       HeapWord* addr = compute_dense_prefix_via_density(id, maximum_compaction);
1782       print_dense_prefix_stats("density", id, maximum_compaction, addr);
1783     }
1784 #endif  // #ifndef PRODUCT
1785 
1786     // Recompute the summary data, taking into account the dense prefix.  If
1787     // every last byte will be reclaimed, then the existing summary data which
1788     // compacts everything can be left in place.
1789     if (!maximum_compaction && dense_prefix_end != space->bottom()) {
1790       // If dead space crosses the dense prefix boundary, it is (at least
1791       // partially) filled with a dummy object, marked live and added to the
1792       // summary data.  This simplifies the copy/update phase and must be done
1793       // before the final locations of objects are determined, to prevent
1794       // leaving a fragment of dead space that is too small to fill.
1795       fill_dense_prefix_end(id);
1796 
1797       // Compute the destination of each Region, and thus each object.
1798       _summary_data.summarize_dense_prefix(space->bottom(), dense_prefix_end);
1799       _summary_data.summarize(_space_info[id].split_info(),
1800                               dense_prefix_end, space->top(), NULL,
1801                               dense_prefix_end, space->end(),
1802                               _space_info[id].new_top_addr());
1803     }
1804   }
1805 
1806   if (TraceParallelOldGCSummaryPhase) {
1807     const size_t region_size = ParallelCompactData::RegionSize;
1808     HeapWord* const dense_prefix_end = _space_info[id].dense_prefix();
1809     const size_t dp_region = _summary_data.addr_to_region_idx(dense_prefix_end);
1810     const size_t dp_words = pointer_delta(dense_prefix_end, space->bottom());
1811     HeapWord* const new_top = _space_info[id].new_top();
1812     const HeapWord* nt_aligned_up = _summary_data.region_align_up(new_top);
1813     const size_t cr_words = pointer_delta(nt_aligned_up, dense_prefix_end);
1814     tty->print_cr("id=%d cap=" SIZE_FORMAT " dp=" PTR_FORMAT " "
1815                   "dp_region=" SIZE_FORMAT " " "dp_count=" SIZE_FORMAT " "
1816                   "cr_count=" SIZE_FORMAT " " "nt=" PTR_FORMAT,
1817                   id, space->capacity_in_words(), dense_prefix_end,
1818                   dp_region, dp_words / region_size,
1819                   cr_words / region_size, new_top);
1820   }
1821 }
1822 
1823 #ifndef PRODUCT
1824 void PSParallelCompact::summary_phase_msg(SpaceId dst_space_id,
1825                                           HeapWord* dst_beg, HeapWord* dst_end,
1826                                           SpaceId src_space_id,
1827                                           HeapWord* src_beg, HeapWord* src_end)
1828 {
1829   if (TraceParallelOldGCSummaryPhase) {
1830     tty->print_cr("summarizing %d [%s] into %d [%s]:  "
1831                   "src=" PTR_FORMAT "-" PTR_FORMAT " "
1832                   SIZE_FORMAT "-" SIZE_FORMAT " "
1833                   "dst=" PTR_FORMAT "-" PTR_FORMAT " "
1834                   SIZE_FORMAT "-" SIZE_FORMAT,
1835                   src_space_id, space_names[src_space_id],
1836                   dst_space_id, space_names[dst_space_id],
1837                   src_beg, src_end,
1838                   _summary_data.addr_to_region_idx(src_beg),
1839                   _summary_data.addr_to_region_idx(src_end),
1840                   dst_beg, dst_end,
1841                   _summary_data.addr_to_region_idx(dst_beg),
1842                   _summary_data.addr_to_region_idx(dst_end));
1843   }
1844 }
1845 #endif  // #ifndef PRODUCT
1846 
1847 void PSParallelCompact::summary_phase(ParCompactionManager* cm,
1848                                       bool maximum_compaction)
1849 {
1850   GCTraceTime tm("summary phase", print_phases(), true, &_gc_timer);
1851   // trace("2");
1852 
1853 #ifdef  ASSERT
1854   if (TraceParallelOldGCMarkingPhase) {
1855     tty->print_cr("add_obj_count=" SIZE_FORMAT " "
1856                   "add_obj_bytes=" SIZE_FORMAT,
1857                   add_obj_count, add_obj_size * HeapWordSize);
1858     tty->print_cr("mark_bitmap_count=" SIZE_FORMAT " "
1859                   "mark_bitmap_bytes=" SIZE_FORMAT,
1860                   mark_bitmap_count, mark_bitmap_size * HeapWordSize);
1861   }
1862 #endif  // #ifdef ASSERT
1863 
1864   // Quick summarization of each space into itself, to see how much is live.
1865   summarize_spaces_quick();
1866 
1867   if (TraceParallelOldGCSummaryPhase) {
1868     tty->print_cr("summary_phase:  after summarizing each space to self");
1869     Universe::print();
1870     NOT_PRODUCT(print_region_ranges());
1871     if (Verbose) {
1872       NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info));
1873     }
1874   }
1875 
1876   // The amount of live data that will end up in old space (assuming it fits).
1877   size_t old_space_total_live = 0;
1878   assert(perm_space_id < old_space_id, "should not count perm data here");
1879   for (unsigned int id = old_space_id; id < last_space_id; ++id) {
1880     old_space_total_live += pointer_delta(_space_info[id].new_top(),
1881                                           _space_info[id].space()->bottom());
1882   }
1883 
1884   MutableSpace* const old_space = _space_info[old_space_id].space();
1885   const size_t old_capacity = old_space->capacity_in_words();
1886   if (old_space_total_live > old_capacity) {
1887     // XXX - should also try to expand
1888     maximum_compaction = true;
1889   }
1890 #ifndef PRODUCT
1891   if (ParallelOldGCSplitALot && old_space_total_live < old_capacity) {
1892     provoke_split(maximum_compaction);
1893   }
1894 #endif // #ifndef PRODUCT
1895 
1896   // Permanent and Old generations.
1897   summarize_space(perm_space_id, maximum_compaction);
1898   summarize_space(old_space_id, maximum_compaction);
1899 
1900   // Summarize the remaining spaces in the young gen.  The initial target space
1901   // is the old gen.  If a space does not fit entirely into the target, then the
1902   // remainder is compacted into the space itself and that space becomes the new
1903   // target.
1904   SpaceId dst_space_id = old_space_id;
1905   HeapWord* dst_space_end = old_space->end();
1906   HeapWord** new_top_addr = _space_info[dst_space_id].new_top_addr();
1907   for (unsigned int id = eden_space_id; id < last_space_id; ++id) {
1908     const MutableSpace* space = _space_info[id].space();
1909     const size_t live = pointer_delta(_space_info[id].new_top(),
1910                                       space->bottom());
1911     const size_t available = pointer_delta(dst_space_end, *new_top_addr);
1912 
1913     NOT_PRODUCT(summary_phase_msg(dst_space_id, *new_top_addr, dst_space_end,
1914                                   SpaceId(id), space->bottom(), space->top());)
1915     if (live > 0 && live <= available) {
1916       // All the live data will fit.
1917       bool done = _summary_data.summarize(_space_info[id].split_info(),
1918                                           space->bottom(), space->top(),
1919                                           NULL,
1920                                           *new_top_addr, dst_space_end,
1921                                           new_top_addr);
1922       assert(done, "space must fit into old gen");
1923 
1924       // Reset the new_top value for the space.
1925       _space_info[id].set_new_top(space->bottom());
1926     } else if (live > 0) {
1927       // Attempt to fit part of the source space into the target space.
1928       HeapWord* next_src_addr = NULL;
1929       bool done = _summary_data.summarize(_space_info[id].split_info(),
1930                                           space->bottom(), space->top(),
1931                                           &next_src_addr,
1932                                           *new_top_addr, dst_space_end,
1933                                           new_top_addr);
1934       assert(!done, "space should not fit into old gen");
1935       assert(next_src_addr != NULL, "sanity");
1936 
1937       // The source space becomes the new target, so the remainder is compacted
1938       // within the space itself.
1939       dst_space_id = SpaceId(id);
1940       dst_space_end = space->end();
1941       new_top_addr = _space_info[id].new_top_addr();
1942       NOT_PRODUCT(summary_phase_msg(dst_space_id,
1943                                     space->bottom(), dst_space_end,
1944                                     SpaceId(id), next_src_addr, space->top());)
1945       done = _summary_data.summarize(_space_info[id].split_info(),
1946                                      next_src_addr, space->top(),
1947                                      NULL,
1948                                      space->bottom(), dst_space_end,
1949                                      new_top_addr);
1950       assert(done, "space must fit when compacted into itself");
1951       assert(*new_top_addr <= space->top(), "usage should not grow");
1952     }
1953   }
1954 
1955   if (TraceParallelOldGCSummaryPhase) {
1956     tty->print_cr("summary_phase:  after final summarization");
1957     Universe::print();
1958     NOT_PRODUCT(print_region_ranges());
1959     if (Verbose) {
1960       NOT_PRODUCT(print_generic_summary_data(_summary_data, _space_info));
1961     }
1962   }
1963 }
1964 
1965 // This method should contain all heap-specific policy for invoking a full
1966 // collection.  invoke_no_policy() will only attempt to compact the heap; it
1967 // will do nothing further.  If we need to bail out for policy reasons, scavenge
1968 // before full gc, or any other specialized behavior, it needs to be added here.
1969 //
1970 // Note that this method should only be called from the vm_thread while at a
1971 // safepoint.
1972 //
1973 // Note that the all_soft_refs_clear flag in the collector policy
1974 // may be true because this method can be called without intervening
1975 // activity.  For example when the heap space is tight and full measure
1976 // are being taken to free space.
1977 void PSParallelCompact::invoke(bool maximum_heap_compaction) {
1978   assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
1979   assert(Thread::current() == (Thread*)VMThread::vm_thread(),
1980          "should be in vm thread");
1981 
1982   ParallelScavengeHeap* heap = gc_heap();
1983   GCCause::Cause gc_cause = heap->gc_cause();
1984   assert(!heap->is_gc_active(), "not reentrant");
1985 
1986   PSAdaptiveSizePolicy* policy = heap->size_policy();
1987   IsGCActiveMark mark;
1988 
1989   if (ScavengeBeforeFullGC) {
1990     PSScavenge::invoke_no_policy();
1991   }
1992 
1993   const bool clear_all_soft_refs =
1994     heap->collector_policy()->should_clear_all_soft_refs();
1995 
1996   PSParallelCompact::invoke_no_policy(clear_all_soft_refs ||
1997                                       maximum_heap_compaction);
1998 }
1999 
2000 bool ParallelCompactData::region_contains(size_t region_index, HeapWord* addr) {
2001   size_t addr_region_index = addr_to_region_idx(addr);
2002   return region_index == addr_region_index;
2003 }
2004 
2005 // This method contains no policy. You should probably
2006 // be calling invoke() instead.
2007 bool PSParallelCompact::invoke_no_policy(bool maximum_heap_compaction) {
2008   assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
2009   assert(ref_processor() != NULL, "Sanity");
2010 
2011   if (GC_locker::check_active_before_gc()) {
2012     return false;
2013   }
2014 
2015   ParallelScavengeHeap* heap = gc_heap();
2016 
2017   _gc_timer.register_gc_start(os::elapsed_counter());
2018   _gc_tracer.report_gc_start(heap->gc_cause(), _gc_timer.gc_start());
2019 
2020   TimeStamp marking_start;
2021   TimeStamp compaction_start;
2022   TimeStamp collection_exit;
2023 
2024   GCCause::Cause gc_cause = heap->gc_cause();
2025   PSYoungGen* young_gen = heap->young_gen();
2026   PSOldGen* old_gen = heap->old_gen();
2027   PSPermGen* perm_gen = heap->perm_gen();
2028   PSAdaptiveSizePolicy* size_policy = heap->size_policy();
2029 
2030   // The scope of casr should end after code that can change
2031   // CollectorPolicy::_should_clear_all_soft_refs.
2032   ClearedAllSoftRefs casr(maximum_heap_compaction,
2033                           heap->collector_policy());
2034 
2035   if (ZapUnusedHeapArea) {
2036     // Save information needed to minimize mangling
2037     heap->record_gen_tops_before_GC();
2038   }
2039 
2040   heap->pre_full_gc_dump(&_gc_timer);
2041 
2042   _print_phases = PrintGCDetails && PrintParallelOldGCPhaseTimes;
2043 
2044   // Make sure data structures are sane, make the heap parsable, and do other
2045   // miscellaneous bookkeeping.
2046   PreGCValues pre_gc_values;
2047   pre_compact(&pre_gc_values);
2048 
2049   // Get the compaction manager reserved for the VM thread.
2050   ParCompactionManager* const vmthread_cm =
2051     ParCompactionManager::manager_array(gc_task_manager()->workers());
2052 
2053   // Place after pre_compact() where the number of invocations is incremented.
2054   AdaptiveSizePolicyOutput(size_policy, heap->total_collections());
2055 
2056   {
2057     ResourceMark rm;
2058     HandleMark hm;
2059 
2060     // Set the number of GC threads to be used in this collection
2061     gc_task_manager()->set_active_gang();
2062     gc_task_manager()->task_idle_workers();
2063     heap->set_par_threads(gc_task_manager()->active_workers());
2064 
2065     gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
2066     TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
2067     GCTraceTime t1(GCCauseString("Full GC", gc_cause), PrintGC, !PrintGCDetails, NULL);
2068     TraceCollectorStats tcs(counters());
2069     TraceMemoryManagerStats tms(true /* Full GC */,gc_cause);
2070 
2071     if (TraceGen1Time) accumulated_time()->start();
2072 
2073     // Let the size policy know we're starting
2074     size_policy->major_collection_begin();
2075 
2076     // When collecting the permanent generation methodOops may be moving,
2077     // so we either have to flush all bcp data or convert it into bci.
2078     CodeCache::gc_prologue();
2079     Threads::gc_prologue();
2080 
2081     COMPILER2_PRESENT(DerivedPointerTable::clear());
2082 
2083     ref_processor()->enable_discovery(true /*verify_disabled*/, true /*verify_no_refs*/);
2084     ref_processor()->setup_policy(maximum_heap_compaction);
2085 
2086     bool marked_for_unloading = false;
2087 
2088     marking_start.update();
2089     marking_phase(vmthread_cm, maximum_heap_compaction, &_gc_tracer);
2090 
2091 #ifndef PRODUCT
2092     if (TraceParallelOldGCMarkingPhase) {
2093       gclog_or_tty->print_cr("marking_phase: cas_tries %d  cas_retries %d "
2094         "cas_by_another %d",
2095         mark_bitmap()->cas_tries(), mark_bitmap()->cas_retries(),
2096         mark_bitmap()->cas_by_another());
2097     }
2098 #endif  // #ifndef PRODUCT
2099 
2100     bool max_on_system_gc = UseMaximumCompactionOnSystemGC
2101       && gc_cause == GCCause::_java_lang_system_gc;
2102     summary_phase(vmthread_cm, maximum_heap_compaction || max_on_system_gc);
2103 
2104     COMPILER2_PRESENT(assert(DerivedPointerTable::is_active(), "Sanity"));
2105     COMPILER2_PRESENT(DerivedPointerTable::set_active(false));
2106 
2107     // adjust_roots() updates Universe::_intArrayKlassObj which is
2108     // needed by the compaction for filling holes in the dense prefix.
2109     adjust_roots();
2110 
2111     compaction_start.update();
2112     // Does the perm gen always have to be done serially because
2113     // klasses are used in the update of an object?
2114     compact_perm(vmthread_cm);
2115 
2116     compact();
2117 
2118     // Reset the mark bitmap, summary data, and do other bookkeeping.  Must be
2119     // done before resizing.
2120     post_compact();
2121 
2122     // Let the size policy know we're done
2123     size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause);
2124 
2125     if (UseAdaptiveSizePolicy) {
2126       if (PrintAdaptiveSizePolicy) {
2127         gclog_or_tty->print("AdaptiveSizeStart: ");
2128         gclog_or_tty->stamp();
2129         gclog_or_tty->print_cr(" collection: %d ",
2130                        heap->total_collections());
2131         if (Verbose) {
2132           gclog_or_tty->print("old_gen_capacity: %d young_gen_capacity: %d"
2133             " perm_gen_capacity: %d ",
2134             old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes(),
2135             perm_gen->capacity_in_bytes());
2136         }
2137       }
2138 
2139       // Don't check if the size_policy is ready here.  Let
2140       // the size_policy check that internally.
2141       if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&
2142           ((gc_cause != GCCause::_java_lang_system_gc) ||
2143             UseAdaptiveSizePolicyWithSystemGC)) {
2144         // Calculate optimal free space amounts
2145         assert(young_gen->max_size() >
2146           young_gen->from_space()->capacity_in_bytes() +
2147           young_gen->to_space()->capacity_in_bytes(),
2148           "Sizes of space in young gen are out-of-bounds");
2149         size_t max_eden_size = young_gen->max_size() -
2150           young_gen->from_space()->capacity_in_bytes() -
2151           young_gen->to_space()->capacity_in_bytes();
2152         size_policy->compute_generation_free_space(
2153                               young_gen->used_in_bytes(),
2154                               young_gen->eden_space()->used_in_bytes(),
2155                               old_gen->used_in_bytes(),
2156                               perm_gen->used_in_bytes(),
2157                               young_gen->eden_space()->capacity_in_bytes(),
2158                               old_gen->max_gen_size(),
2159                               max_eden_size,
2160                               true /* full gc*/,
2161                               gc_cause,
2162                               heap->collector_policy());
2163 
2164         heap->resize_old_gen(
2165           size_policy->calculated_old_free_size_in_bytes());
2166 
2167         // Don't resize the young generation at an major collection.  A
2168         // desired young generation size may have been calculated but
2169         // resizing the young generation complicates the code because the
2170         // resizing of the old generation may have moved the boundary
2171         // between the young generation and the old generation.  Let the
2172         // young generation resizing happen at the minor collections.
2173       }
2174       if (PrintAdaptiveSizePolicy) {
2175         gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ",
2176                        heap->total_collections());
2177       }
2178     }
2179 
2180     if (UsePerfData) {
2181       PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters();
2182       counters->update_counters();
2183       counters->update_old_capacity(old_gen->capacity_in_bytes());
2184       counters->update_young_capacity(young_gen->capacity_in_bytes());
2185     }
2186 
2187     heap->resize_all_tlabs();
2188 
2189     // We collected the perm gen, so we'll resize it here.
2190     perm_gen->compute_new_size(pre_gc_values.perm_gen_used());
2191 
2192     if (TraceGen1Time) accumulated_time()->stop();
2193 
2194     if (PrintGC) {
2195       if (PrintGCDetails) {
2196         // No GC timestamp here.  This is after GC so it would be confusing.
2197         young_gen->print_used_change(pre_gc_values.young_gen_used());
2198         old_gen->print_used_change(pre_gc_values.old_gen_used());
2199         heap->print_heap_change(pre_gc_values.heap_used());
2200         // Print perm gen last (print_heap_change() excludes the perm gen).
2201         perm_gen->print_used_change(pre_gc_values.perm_gen_used());
2202       } else {
2203         heap->print_heap_change(pre_gc_values.heap_used());
2204       }
2205     }
2206 
2207     // Track memory usage and detect low memory
2208     MemoryService::track_memory_usage();
2209     heap->update_counters();
2210     gc_task_manager()->release_idle_workers();
2211   }
2212 
2213 #ifdef ASSERT
2214   for (size_t i = 0; i < ParallelGCThreads + 1; ++i) {
2215     ParCompactionManager* const cm =
2216       ParCompactionManager::manager_array(int(i));
2217     assert(cm->marking_stack()->is_empty(),       "should be empty");
2218     assert(ParCompactionManager::region_list(int(i))->is_empty(), "should be empty");
2219     assert(cm->revisit_klass_stack()->is_empty(), "should be empty");
2220   }
2221 #endif // ASSERT
2222 
2223   if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
2224     HandleMark hm;  // Discard invalid handles created during verification
2225     gclog_or_tty->print(" VerifyAfterGC:");
2226     Universe::verify();
2227   }
2228 
2229   // Re-verify object start arrays
2230   if (VerifyObjectStartArray &&
2231       VerifyAfterGC) {
2232     old_gen->verify_object_start_array();
2233     perm_gen->verify_object_start_array();
2234   }
2235 
2236   if (ZapUnusedHeapArea) {
2237     old_gen->object_space()->check_mangled_unused_area_complete();
2238     perm_gen->object_space()->check_mangled_unused_area_complete();
2239   }
2240 
2241   NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
2242 
2243   collection_exit.update();
2244 
2245   heap->print_heap_after_gc();
2246   heap->trace_heap_after_gc(&_gc_tracer);
2247 
2248   if (PrintGCTaskTimeStamps) {
2249     gclog_or_tty->print_cr("VM-Thread " INT64_FORMAT " " INT64_FORMAT " "
2250                            INT64_FORMAT,
2251                            marking_start.ticks(), compaction_start.ticks(),
2252                            collection_exit.ticks());
2253     gc_task_manager()->print_task_time_stamps();
2254   }
2255 
2256   heap->post_full_gc_dump(&_gc_timer);
2257 
2258 #ifdef TRACESPINNING
2259   ParallelTaskTerminator::print_termination_counts();
2260 #endif
2261 
2262   _gc_timer.register_gc_end(os::elapsed_counter());
2263 
2264   _gc_tracer.report_dense_prefix(dense_prefix(old_space_id));
2265   _gc_tracer.report_gc_end(_gc_timer.gc_end(), _gc_timer.time_partitions());
2266 
2267   return true;
2268 }
2269 
2270 bool PSParallelCompact::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
2271                                              PSYoungGen* young_gen,
2272                                              PSOldGen* old_gen) {
2273   MutableSpace* const eden_space = young_gen->eden_space();
2274   assert(!eden_space->is_empty(), "eden must be non-empty");
2275   assert(young_gen->virtual_space()->alignment() ==
2276          old_gen->virtual_space()->alignment(), "alignments do not match");
2277 
2278   if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) {
2279     return false;
2280   }
2281 
2282   // Both generations must be completely committed.
2283   if (young_gen->virtual_space()->uncommitted_size() != 0) {
2284     return false;
2285   }
2286   if (old_gen->virtual_space()->uncommitted_size() != 0) {
2287     return false;
2288   }
2289 
2290   // Figure out how much to take from eden.  Include the average amount promoted
2291   // in the total; otherwise the next young gen GC will simply bail out to a
2292   // full GC.
2293   const size_t alignment = old_gen->virtual_space()->alignment();
2294   const size_t eden_used = eden_space->used_in_bytes();
2295   const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average();
2296   const size_t absorb_size = align_size_up(eden_used + promoted, alignment);
2297   const size_t eden_capacity = eden_space->capacity_in_bytes();
2298 
2299   if (absorb_size >= eden_capacity) {
2300     return false; // Must leave some space in eden.
2301   }
2302 
2303   const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size;
2304   if (new_young_size < young_gen->min_gen_size()) {
2305     return false; // Respect young gen minimum size.
2306   }
2307 
2308   if (TraceAdaptiveGCBoundary && Verbose) {
2309     gclog_or_tty->print(" absorbing " SIZE_FORMAT "K:  "
2310                         "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K "
2311                         "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K "
2312                         "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ",
2313                         absorb_size / K,
2314                         eden_capacity / K, (eden_capacity - absorb_size) / K,
2315                         young_gen->from_space()->used_in_bytes() / K,
2316                         young_gen->to_space()->used_in_bytes() / K,
2317                         young_gen->capacity_in_bytes() / K, new_young_size / K);
2318   }
2319 
2320   // Fill the unused part of the old gen.
2321   MutableSpace* const old_space = old_gen->object_space();
2322   HeapWord* const unused_start = old_space->top();
2323   size_t const unused_words = pointer_delta(old_space->end(), unused_start);
2324 
2325   if (unused_words > 0) {
2326     if (unused_words < CollectedHeap::min_fill_size()) {
2327       return false;  // If the old gen cannot be filled, must give up.
2328     }
2329     CollectedHeap::fill_with_objects(unused_start, unused_words);
2330   }
2331 
2332   // Take the live data from eden and set both top and end in the old gen to
2333   // eden top.  (Need to set end because reset_after_change() mangles the region
2334   // from end to virtual_space->high() in debug builds).
2335   HeapWord* const new_top = eden_space->top();
2336   old_gen->virtual_space()->expand_into(young_gen->virtual_space(),
2337                                         absorb_size);
2338   young_gen->reset_after_change();
2339   old_space->set_top(new_top);
2340   old_space->set_end(new_top);
2341   old_gen->reset_after_change();
2342 
2343   // Update the object start array for the filler object and the data from eden.
2344   ObjectStartArray* const start_array = old_gen->start_array();
2345   for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) {
2346     start_array->allocate_block(p);
2347   }
2348 
2349   // Could update the promoted average here, but it is not typically updated at
2350   // full GCs and the value to use is unclear.  Something like
2351   //
2352   // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc.
2353 
2354   size_policy->set_bytes_absorbed_from_eden(absorb_size);
2355   return true;
2356 }
2357 
2358 GCTaskManager* const PSParallelCompact::gc_task_manager() {
2359   assert(ParallelScavengeHeap::gc_task_manager() != NULL,
2360     "shouldn't return NULL");
2361   return ParallelScavengeHeap::gc_task_manager();
2362 }
2363 
2364 void PSParallelCompact::marking_phase(ParCompactionManager* cm, bool maximum_heap_compaction) {
2365   // Recursively traverse all live objects and mark them
2366   GCTraceTime tm("marking phase", print_phases(), true, &_gc_timer);
2367 
2368   ParallelScavengeHeap* heap = gc_heap();
2369   uint parallel_gc_threads = heap->gc_task_manager()->workers();
2370   uint active_gc_threads = heap->gc_task_manager()->active_workers();
2371   TaskQueueSetSuper* qset = ParCompactionManager::region_array();
2372   ParallelTaskTerminator terminator(active_gc_threads, qset);
2373 
2374   PSParallelCompact::MarkAndPushClosure mark_and_push_closure(cm);
2375   PSParallelCompact::FollowStackClosure follow_stack_closure(cm);
2376 
2377   {
2378     GCTraceTime tm_m("par mark", print_phases(), true, &_gc_timer);
2379 
2380     ParallelScavengeHeap::ParStrongRootsScope psrs;
2381 
2382     GCTaskQueue* q = GCTaskQueue::create();
2383 
2384     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::universe));
2385     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jni_handles));
2386     // We scan the thread roots in parallel
2387     Threads::create_thread_roots_marking_tasks(q);
2388     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::object_synchronizer));
2389     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::flat_profiler));
2390     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::management));
2391     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::system_dictionary));
2392     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jvmti));
2393     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::code_cache));
2394 
2395     if (active_gc_threads > 1) {
2396       for (uint j = 0; j < active_gc_threads; j++) {
2397         q->enqueue(new StealMarkingTask(&terminator));
2398       }
2399     }
2400 
2401     gc_task_manager()->execute_and_wait(q);
2402   }
2403 
2404   // Process reference objects found during marking
2405   {
2406     GCTraceTime tm_r("reference processing", print_phases(), true, &_gc_timer);
2407 
2408     ReferenceProcessorStats stats;
2409     if (ref_processor()->processing_is_mt()) {
2410       RefProcTaskExecutor task_executor;
2411       stats = ref_processor()->process_discovered_references(
2412         is_alive_closure(), &mark_and_push_closure, &follow_stack_closure,
2413         &task_executor, &_gc_timer);
2414     } else {
2415       stats = ref_processor()->process_discovered_references(
2416         is_alive_closure(), &mark_and_push_closure, &follow_stack_closure, NULL,
2417         &_gc_timer);
2418     }
2419 
2420     _gc_tracer->report_gc_reference_stats(stats);
2421   }
2422 
2423   GCTraceTime tm_c("class unloading", print_phases(), true, &_gc_timer);
2424 
2425   // Follow system dictionary roots and unload classes.
2426   bool purged_class = SystemDictionary::do_unloading(is_alive_closure());
2427 
2428   // Follow code cache roots.
2429   CodeCache::do_unloading(is_alive_closure(), &mark_and_push_closure,
2430                           purged_class);
2431   cm->follow_marking_stacks(); // Flush marking stack.
2432 
2433   // Update subklass/sibling/implementor links of live klasses
2434   // revisit_klass_stack is used in follow_weak_klass_links().
2435   follow_weak_klass_links();
2436 
2437   // Revisit memoized MDO's and clear any unmarked weak refs
2438   follow_mdo_weak_refs();
2439 
2440   // Visit interned string tables and delete unmarked oops
2441   StringTable::unlink(is_alive_closure());
2442   // Clean up unreferenced symbols in symbol table.
2443   SymbolTable::unlink();
2444 
2445   assert(cm->marking_stacks_empty(), "marking stacks should be empty");
2446 }
2447 
2448 // This should be moved to the shared markSweep code!
2449 class PSAlwaysTrueClosure: public BoolObjectClosure {
2450 public:
2451   void do_object(oop p) { ShouldNotReachHere(); }
2452   bool do_object_b(oop p) { return true; }
2453 };
2454 static PSAlwaysTrueClosure always_true;
2455 
2456 void PSParallelCompact::adjust_roots() {
2457   // Adjust the pointers to reflect the new locations
2458   GCTraceTime tm("adjust roots", print_phases(), true, &_gc_timer);
2459 
2460   // General strong roots.
2461   Universe::oops_do(adjust_root_pointer_closure());
2462   JNIHandles::oops_do(adjust_root_pointer_closure());   // Global (strong) JNI handles
2463   Threads::oops_do(adjust_root_pointer_closure(), NULL);
2464   ObjectSynchronizer::oops_do(adjust_root_pointer_closure());
2465   FlatProfiler::oops_do(adjust_root_pointer_closure());
2466   Management::oops_do(adjust_root_pointer_closure());
2467   JvmtiExport::oops_do(adjust_root_pointer_closure());
2468   // SO_AllClasses
2469   SystemDictionary::oops_do(adjust_root_pointer_closure());
2470 
2471   // Now adjust pointers in remaining weak roots.  (All of which should
2472   // have been cleared if they pointed to non-surviving objects.)
2473   // Global (weak) JNI handles
2474   JNIHandles::weak_oops_do(&always_true, adjust_root_pointer_closure());
2475 
2476   CodeCache::oops_do(adjust_pointer_closure());
2477   StringTable::oops_do(adjust_root_pointer_closure());
2478   ref_processor()->weak_oops_do(adjust_root_pointer_closure());
2479   // Roots were visited so references into the young gen in roots
2480   // may have been scanned.  Process them also.
2481   // Should the reference processor have a span that excludes
2482   // young gen objects?
2483   PSScavenge::reference_processor()->weak_oops_do(
2484                                               adjust_root_pointer_closure());
2485 }
2486 
2487 void PSParallelCompact::compact_perm(ParCompactionManager* cm) {
2488   GCTraceTime tm("compact perm gen", print_phases(), true, &_gc_timer);
2489   // trace("4");
2490 
2491   gc_heap()->perm_gen()->start_array()->reset();
2492   move_and_update(cm, perm_space_id);
2493 }
2494 
2495 void PSParallelCompact::enqueue_region_draining_tasks(GCTaskQueue* q,
2496                                                       uint parallel_gc_threads)
2497 {
2498   GCTraceTime tm("drain task setup", print_phases(), true, &_gc_timer);
2499 
2500   // Find the threads that are active
2501   unsigned int which = 0;
2502 
2503   const uint task_count = MAX2(parallel_gc_threads, 1U);
2504   for (uint j = 0; j < task_count; j++) {
2505     q->enqueue(new DrainStacksCompactionTask(j));
2506     ParCompactionManager::verify_region_list_empty(j);
2507     // Set the region stacks variables to "no" region stack values
2508     // so that they will be recognized and needing a region stack
2509     // in the stealing tasks if they do not get one by executing
2510     // a draining stack.
2511     ParCompactionManager* cm = ParCompactionManager::manager_array(j);
2512     cm->set_region_stack(NULL);
2513     cm->set_region_stack_index((uint)max_uintx);
2514   }
2515   ParCompactionManager::reset_recycled_stack_index();
2516 
2517   // Find all regions that are available (can be filled immediately) and
2518   // distribute them to the thread stacks.  The iteration is done in reverse
2519   // order (high to low) so the regions will be removed in ascending order.
2520 
2521   const ParallelCompactData& sd = PSParallelCompact::summary_data();
2522 
2523   size_t fillable_regions = 0;   // A count for diagnostic purposes.
2524   // A region index which corresponds to the tasks created above.
2525   // "which" must be 0 <= which < task_count
2526 
2527   which = 0;
2528   for (unsigned int id = to_space_id; id > perm_space_id; --id) {
2529     SpaceInfo* const space_info = _space_info + id;
2530     MutableSpace* const space = space_info->space();
2531     HeapWord* const new_top = space_info->new_top();
2532 
2533     const size_t beg_region = sd.addr_to_region_idx(space_info->dense_prefix());
2534     const size_t end_region =
2535       sd.addr_to_region_idx(sd.region_align_up(new_top));
2536     assert(end_region > 0, "perm gen cannot be empty");
2537 
2538     for (size_t cur = end_region - 1; cur >= beg_region; --cur) {
2539       if (sd.region(cur)->claim_unsafe()) {
2540         ParCompactionManager::region_list_push(which, cur);
2541 
2542         if (TraceParallelOldGCCompactionPhase && Verbose) {
2543           const size_t count_mod_8 = fillable_regions & 7;
2544           if (count_mod_8 == 0) gclog_or_tty->print("fillable: ");
2545           gclog_or_tty->print(" " SIZE_FORMAT_W(7), cur);
2546           if (count_mod_8 == 7) gclog_or_tty->cr();
2547         }
2548 
2549         NOT_PRODUCT(++fillable_regions;)
2550 
2551         // Assign regions to tasks in round-robin fashion.
2552         if (++which == task_count) {
2553           assert(which <= parallel_gc_threads,
2554             "Inconsistent number of workers");
2555           which = 0;
2556         }
2557       }
2558     }
2559   }
2560 
2561   if (TraceParallelOldGCCompactionPhase) {
2562     if (Verbose && (fillable_regions & 7) != 0) gclog_or_tty->cr();
2563     gclog_or_tty->print_cr("%u initially fillable regions", fillable_regions);
2564   }
2565 }
2566 
2567 #define PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING 4
2568 
2569 void PSParallelCompact::enqueue_dense_prefix_tasks(GCTaskQueue* q,
2570                                                     uint parallel_gc_threads) {
2571   GCTraceTime tm("dense prefix task setup", print_phases(), true, &_gc_timer);
2572 
2573   ParallelCompactData& sd = PSParallelCompact::summary_data();
2574 
2575   // Iterate over all the spaces adding tasks for updating
2576   // regions in the dense prefix.  Assume that 1 gc thread
2577   // will work on opening the gaps and the remaining gc threads
2578   // will work on the dense prefix.
2579   unsigned int space_id;
2580   for (space_id = old_space_id; space_id < last_space_id; ++ space_id) {
2581     HeapWord* const dense_prefix_end = _space_info[space_id].dense_prefix();
2582     const MutableSpace* const space = _space_info[space_id].space();
2583 
2584     if (dense_prefix_end == space->bottom()) {
2585       // There is no dense prefix for this space.
2586       continue;
2587     }
2588 
2589     // The dense prefix is before this region.
2590     size_t region_index_end_dense_prefix =
2591         sd.addr_to_region_idx(dense_prefix_end);
2592     RegionData* const dense_prefix_cp =
2593       sd.region(region_index_end_dense_prefix);
2594     assert(dense_prefix_end == space->end() ||
2595            dense_prefix_cp->available() ||
2596            dense_prefix_cp->claimed(),
2597            "The region after the dense prefix should always be ready to fill");
2598 
2599     size_t region_index_start = sd.addr_to_region_idx(space->bottom());
2600 
2601     // Is there dense prefix work?
2602     size_t total_dense_prefix_regions =
2603       region_index_end_dense_prefix - region_index_start;
2604     // How many regions of the dense prefix should be given to
2605     // each thread?
2606     if (total_dense_prefix_regions > 0) {
2607       uint tasks_for_dense_prefix = 1;
2608       if (total_dense_prefix_regions <=
2609           (parallel_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING)) {
2610         // Don't over partition.  This assumes that
2611         // PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING is a small integer value
2612         // so there are not many regions to process.
2613         tasks_for_dense_prefix = parallel_gc_threads;
2614       } else {
2615         // Over partition
2616         tasks_for_dense_prefix = parallel_gc_threads *
2617           PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING;
2618       }
2619       size_t regions_per_thread = total_dense_prefix_regions /
2620         tasks_for_dense_prefix;
2621       // Give each thread at least 1 region.
2622       if (regions_per_thread == 0) {
2623         regions_per_thread = 1;
2624       }
2625 
2626       for (uint k = 0; k < tasks_for_dense_prefix; k++) {
2627         if (region_index_start >= region_index_end_dense_prefix) {
2628           break;
2629         }
2630         // region_index_end is not processed
2631         size_t region_index_end = MIN2(region_index_start + regions_per_thread,
2632                                        region_index_end_dense_prefix);
2633         q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id),
2634                                              region_index_start,
2635                                              region_index_end));
2636         region_index_start = region_index_end;
2637       }
2638     }
2639     // This gets any part of the dense prefix that did not
2640     // fit evenly.
2641     if (region_index_start < region_index_end_dense_prefix) {
2642       q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id),
2643                                            region_index_start,
2644                                            region_index_end_dense_prefix));
2645     }
2646   }
2647 }
2648 
2649 void PSParallelCompact::enqueue_region_stealing_tasks(
2650                                      GCTaskQueue* q,
2651                                      ParallelTaskTerminator* terminator_ptr,
2652                                      uint parallel_gc_threads) {
2653   GCTraceTime tm("steal task setup", print_phases(), true, &_gc_timer);
2654 
2655   // Once a thread has drained it's stack, it should try to steal regions from
2656   // other threads.
2657   if (parallel_gc_threads > 1) {
2658     for (uint j = 0; j < parallel_gc_threads; j++) {
2659       q->enqueue(new StealRegionCompactionTask(terminator_ptr));
2660     }
2661   }
2662 }
2663 
2664 void PSParallelCompact::compact() {
2665   // trace("5");
2666   GCTraceTime tm("compaction phase", print_phases(), true, &_gc_timer);
2667 
2668   ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
2669   assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
2670   PSOldGen* old_gen = heap->old_gen();
2671   old_gen->start_array()->reset();
2672   uint parallel_gc_threads = heap->gc_task_manager()->workers();
2673   uint active_gc_threads = heap->gc_task_manager()->active_workers();
2674   TaskQueueSetSuper* qset = ParCompactionManager::region_array();
2675   ParallelTaskTerminator terminator(active_gc_threads, qset);
2676 
2677   GCTaskQueue* q = GCTaskQueue::create();
2678   enqueue_region_draining_tasks(q, active_gc_threads);
2679   enqueue_dense_prefix_tasks(q, active_gc_threads);
2680   enqueue_region_stealing_tasks(q, &terminator, active_gc_threads);
2681 
2682   {
2683     GCTraceTime tm_pc("par compact", print_phases(), true, &_gc_timer);
2684 
2685     gc_task_manager()->execute_and_wait(q);
2686 
2687 #ifdef  ASSERT
2688     // Verify that all regions have been processed before the deferred updates.
2689     // Note that perm_space_id is skipped; this type of verification is not
2690     // valid until the perm gen is compacted by regions.
2691     for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2692       verify_complete(SpaceId(id));
2693     }
2694 #endif
2695   }
2696 
2697   {
2698     // Update the deferred objects, if any.  Any compaction manager can be used.
2699     GCTraceTime tm_du("deferred updates", print_phases(), true, &_gc_timer);
2700     ParCompactionManager* cm = ParCompactionManager::manager_array(0);
2701     for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2702       update_deferred_objects(cm, SpaceId(id));
2703     }
2704   }
2705 }
2706 
2707 #ifdef  ASSERT
2708 void PSParallelCompact::verify_complete(SpaceId space_id) {
2709   // All Regions between space bottom() to new_top() should be marked as filled
2710   // and all Regions between new_top() and top() should be available (i.e.,
2711   // should have been emptied).
2712   ParallelCompactData& sd = summary_data();
2713   SpaceInfo si = _space_info[space_id];
2714   HeapWord* new_top_addr = sd.region_align_up(si.new_top());
2715   HeapWord* old_top_addr = sd.region_align_up(si.space()->top());
2716   const size_t beg_region = sd.addr_to_region_idx(si.space()->bottom());
2717   const size_t new_top_region = sd.addr_to_region_idx(new_top_addr);
2718   const size_t old_top_region = sd.addr_to_region_idx(old_top_addr);
2719 
2720   bool issued_a_warning = false;
2721 
2722   size_t cur_region;
2723   for (cur_region = beg_region; cur_region < new_top_region; ++cur_region) {
2724     const RegionData* const c = sd.region(cur_region);
2725     if (!c->completed()) {
2726       warning("region " SIZE_FORMAT " not filled:  "
2727               "destination_count=" SIZE_FORMAT,
2728               cur_region, c->destination_count());
2729       issued_a_warning = true;
2730     }
2731   }
2732 
2733   for (cur_region = new_top_region; cur_region < old_top_region; ++cur_region) {
2734     const RegionData* const c = sd.region(cur_region);
2735     if (!c->available()) {
2736       warning("region " SIZE_FORMAT " not empty:   "
2737               "destination_count=" SIZE_FORMAT,
2738               cur_region, c->destination_count());
2739       issued_a_warning = true;
2740     }
2741   }
2742 
2743   if (issued_a_warning) {
2744     print_region_ranges();
2745   }
2746 }
2747 #endif  // #ifdef ASSERT
2748 
2749 void
2750 PSParallelCompact::follow_weak_klass_links() {
2751   // All klasses on the revisit stack are marked at this point.
2752   // Update and follow all subklass, sibling and implementor links.
2753   // Check all the stacks here even if not all the workers are active.
2754   // There is no accounting which indicates which stacks might have
2755   // contents to be followed.
2756   if (PrintRevisitStats) {
2757     gclog_or_tty->print_cr("#classes in system dictionary = %d",
2758                            SystemDictionary::number_of_classes());
2759   }
2760   for (uint i = 0; i < ParallelGCThreads + 1; i++) {
2761     ParCompactionManager* cm = ParCompactionManager::manager_array(i);
2762     KeepAliveClosure keep_alive_closure(cm);
2763     Stack<Klass*, mtGC>* const rks = cm->revisit_klass_stack();
2764     if (PrintRevisitStats) {
2765       gclog_or_tty->print_cr("Revisit klass stack[%u] length = " SIZE_FORMAT,
2766                              i, rks->size());
2767     }
2768     while (!rks->is_empty()) {
2769       Klass* const k = rks->pop();
2770       k->follow_weak_klass_links(is_alive_closure(), &keep_alive_closure);
2771     }
2772 
2773     cm->follow_marking_stacks();
2774   }
2775 }
2776 
2777 void
2778 PSParallelCompact::revisit_weak_klass_link(ParCompactionManager* cm, Klass* k) {
2779   cm->revisit_klass_stack()->push(k);
2780 }
2781 
2782 void PSParallelCompact::revisit_mdo(ParCompactionManager* cm, DataLayout* p) {
2783   cm->revisit_mdo_stack()->push(p);
2784 }
2785 
2786 void PSParallelCompact::follow_mdo_weak_refs() {
2787   // All strongly reachable oops have been marked at this point;
2788   // we can visit and clear any weak references from MDO's which
2789   // we memoized during the strong marking phase.
2790   if (PrintRevisitStats) {
2791     gclog_or_tty->print_cr("#classes in system dictionary = %d",
2792                            SystemDictionary::number_of_classes());
2793   }
2794   for (uint i = 0; i < ParallelGCThreads + 1; i++) {
2795     ParCompactionManager* cm = ParCompactionManager::manager_array(i);
2796     Stack<DataLayout*, mtGC>* rms = cm->revisit_mdo_stack();
2797     if (PrintRevisitStats) {
2798       gclog_or_tty->print_cr("Revisit MDO stack[%u] size = " SIZE_FORMAT,
2799                              i, rms->size());
2800     }
2801     while (!rms->is_empty()) {
2802       rms->pop()->follow_weak_refs(is_alive_closure());
2803     }
2804 
2805     cm->follow_marking_stacks();
2806   }
2807 }
2808 
2809 
2810 #ifdef VALIDATE_MARK_SWEEP
2811 
2812 void PSParallelCompact::track_adjusted_pointer(void* p, bool isroot) {
2813   if (!ValidateMarkSweep)
2814     return;
2815 
2816   if (!isroot) {
2817     if (_pointer_tracking) {
2818       guarantee(_adjusted_pointers->contains(p), "should have seen this pointer");
2819       _adjusted_pointers->remove(p);
2820     }
2821   } else {
2822     ptrdiff_t index = _root_refs_stack->find(p);
2823     if (index != -1) {
2824       int l = _root_refs_stack->length();
2825       if (l > 0 && l - 1 != index) {
2826         void* last = _root_refs_stack->pop();
2827         assert(last != p, "should be different");
2828         _root_refs_stack->at_put(index, last);
2829       } else {
2830         _root_refs_stack->remove(p);
2831       }
2832     }
2833   }
2834 }
2835 
2836 
2837 void PSParallelCompact::check_adjust_pointer(void* p) {
2838   _adjusted_pointers->push(p);
2839 }
2840 
2841 
2842 class AdjusterTracker: public OopClosure {
2843  public:
2844   AdjusterTracker() {};
2845   void do_oop(oop* o)         { PSParallelCompact::check_adjust_pointer(o); }
2846   void do_oop(narrowOop* o)   { PSParallelCompact::check_adjust_pointer(o); }
2847 };
2848 
2849 
2850 void PSParallelCompact::track_interior_pointers(oop obj) {
2851   if (ValidateMarkSweep) {
2852     _adjusted_pointers->clear();
2853     _pointer_tracking = true;
2854 
2855     AdjusterTracker checker;
2856     obj->oop_iterate(&checker);
2857   }
2858 }
2859 
2860 
2861 void PSParallelCompact::check_interior_pointers() {
2862   if (ValidateMarkSweep) {
2863     _pointer_tracking = false;
2864     guarantee(_adjusted_pointers->length() == 0, "should have processed the same pointers");
2865   }
2866 }
2867 
2868 
2869 void PSParallelCompact::reset_live_oop_tracking(bool at_perm) {
2870   if (ValidateMarkSweep) {
2871     guarantee((size_t)_live_oops->length() == _live_oops_index, "should be at end of live oops");
2872     _live_oops_index = at_perm ? _live_oops_index_at_perm : 0;
2873   }
2874 }
2875 
2876 
2877 void PSParallelCompact::register_live_oop(oop p, size_t size) {
2878   if (ValidateMarkSweep) {
2879     _live_oops->push(p);
2880     _live_oops_size->push(size);
2881     _live_oops_index++;
2882   }
2883 }
2884 
2885 void PSParallelCompact::validate_live_oop(oop p, size_t size) {
2886   if (ValidateMarkSweep) {
2887     oop obj = _live_oops->at((int)_live_oops_index);
2888     guarantee(obj == p, "should be the same object");
2889     guarantee(_live_oops_size->at((int)_live_oops_index) == size, "should be the same size");
2890     _live_oops_index++;
2891   }
2892 }
2893 
2894 void PSParallelCompact::live_oop_moved_to(HeapWord* q, size_t size,
2895                                   HeapWord* compaction_top) {
2896   assert(oop(q)->forwardee() == NULL || oop(q)->forwardee() == oop(compaction_top),
2897          "should be moved to forwarded location");
2898   if (ValidateMarkSweep) {
2899     PSParallelCompact::validate_live_oop(oop(q), size);
2900     _live_oops_moved_to->push(oop(compaction_top));
2901   }
2902   if (RecordMarkSweepCompaction) {
2903     _cur_gc_live_oops->push(q);
2904     _cur_gc_live_oops_moved_to->push(compaction_top);
2905     _cur_gc_live_oops_size->push(size);
2906   }
2907 }
2908 
2909 
2910 void PSParallelCompact::compaction_complete() {
2911   if (RecordMarkSweepCompaction) {
2912     GrowableArray<HeapWord*>* _tmp_live_oops          = _cur_gc_live_oops;
2913     GrowableArray<HeapWord*>* _tmp_live_oops_moved_to = _cur_gc_live_oops_moved_to;
2914     GrowableArray<size_t>   * _tmp_live_oops_size     = _cur_gc_live_oops_size;
2915 
2916     _cur_gc_live_oops           = _last_gc_live_oops;
2917     _cur_gc_live_oops_moved_to  = _last_gc_live_oops_moved_to;
2918     _cur_gc_live_oops_size      = _last_gc_live_oops_size;
2919     _last_gc_live_oops          = _tmp_live_oops;
2920     _last_gc_live_oops_moved_to = _tmp_live_oops_moved_to;
2921     _last_gc_live_oops_size     = _tmp_live_oops_size;
2922   }
2923 }
2924 
2925 
2926 void PSParallelCompact::print_new_location_of_heap_address(HeapWord* q) {
2927   if (!RecordMarkSweepCompaction) {
2928     tty->print_cr("Requires RecordMarkSweepCompaction to be enabled");
2929     return;
2930   }
2931 
2932   if (_last_gc_live_oops == NULL) {
2933     tty->print_cr("No compaction information gathered yet");
2934     return;
2935   }
2936 
2937   for (int i = 0; i < _last_gc_live_oops->length(); i++) {
2938     HeapWord* old_oop = _last_gc_live_oops->at(i);
2939     size_t    sz      = _last_gc_live_oops_size->at(i);
2940     if (old_oop <= q && q < (old_oop + sz)) {
2941       HeapWord* new_oop = _last_gc_live_oops_moved_to->at(i);
2942       size_t offset = (q - old_oop);
2943       tty->print_cr("Address " PTR_FORMAT, q);
2944       tty->print_cr(" Was in oop " PTR_FORMAT ", size %d, at offset %d", old_oop, sz, offset);
2945       tty->print_cr(" Now in oop " PTR_FORMAT ", actual address " PTR_FORMAT, new_oop, new_oop + offset);
2946       return;
2947     }
2948   }
2949 
2950   tty->print_cr("Address " PTR_FORMAT " not found in live oop information from last GC", q);
2951 }
2952 #endif //VALIDATE_MARK_SWEEP
2953 
2954 // Update interior oops in the ranges of regions [beg_region, end_region).
2955 void
2956 PSParallelCompact::update_and_deadwood_in_dense_prefix(ParCompactionManager* cm,
2957                                                        SpaceId space_id,
2958                                                        size_t beg_region,
2959                                                        size_t end_region) {
2960   ParallelCompactData& sd = summary_data();
2961   ParMarkBitMap* const mbm = mark_bitmap();
2962 
2963   HeapWord* beg_addr = sd.region_to_addr(beg_region);
2964   HeapWord* const end_addr = sd.region_to_addr(end_region);
2965   assert(beg_region <= end_region, "bad region range");
2966   assert(end_addr <= dense_prefix(space_id), "not in the dense prefix");
2967 
2968 #ifdef  ASSERT
2969   // Claim the regions to avoid triggering an assert when they are marked as
2970   // filled.
2971   for (size_t claim_region = beg_region; claim_region < end_region; ++claim_region) {
2972     assert(sd.region(claim_region)->claim_unsafe(), "claim() failed");
2973   }
2974 #endif  // #ifdef ASSERT
2975 
2976   if (beg_addr != space(space_id)->bottom()) {
2977     // Find the first live object or block of dead space that *starts* in this
2978     // range of regions.  If a partial object crosses onto the region, skip it;
2979     // it will be marked for 'deferred update' when the object head is
2980     // processed.  If dead space crosses onto the region, it is also skipped; it
2981     // will be filled when the prior region is processed.  If neither of those
2982     // apply, the first word in the region is the start of a live object or dead
2983     // space.
2984     assert(beg_addr > space(space_id)->bottom(), "sanity");
2985     const RegionData* const cp = sd.region(beg_region);
2986     if (cp->partial_obj_size() != 0) {
2987       beg_addr = sd.partial_obj_end(beg_region);
2988     } else if (dead_space_crosses_boundary(cp, mbm->addr_to_bit(beg_addr))) {
2989       beg_addr = mbm->find_obj_beg(beg_addr, end_addr);
2990     }
2991   }
2992 
2993   if (beg_addr < end_addr) {
2994     // A live object or block of dead space starts in this range of Regions.
2995      HeapWord* const dense_prefix_end = dense_prefix(space_id);
2996 
2997     // Create closures and iterate.
2998     UpdateOnlyClosure update_closure(mbm, cm, space_id);
2999     FillClosure fill_closure(cm, space_id);
3000     ParMarkBitMap::IterationStatus status;
3001     status = mbm->iterate(&update_closure, &fill_closure, beg_addr, end_addr,
3002                           dense_prefix_end);
3003     if (status == ParMarkBitMap::incomplete) {
3004       update_closure.do_addr(update_closure.source());
3005     }
3006   }
3007 
3008   // Mark the regions as filled.
3009   RegionData* const beg_cp = sd.region(beg_region);
3010   RegionData* const end_cp = sd.region(end_region);
3011   for (RegionData* cp = beg_cp; cp < end_cp; ++cp) {
3012     cp->set_completed();
3013   }
3014 }
3015 
3016 // Return the SpaceId for the space containing addr.  If addr is not in the
3017 // heap, last_space_id is returned.  In debug mode it expects the address to be
3018 // in the heap and asserts such.
3019 PSParallelCompact::SpaceId PSParallelCompact::space_id(HeapWord* addr) {
3020   assert(Universe::heap()->is_in_reserved(addr), "addr not in the heap");
3021 
3022   for (unsigned int id = perm_space_id; id < last_space_id; ++id) {
3023     if (_space_info[id].space()->contains(addr)) {
3024       return SpaceId(id);
3025     }
3026   }
3027 
3028   assert(false, "no space contains the addr");
3029   return last_space_id;
3030 }
3031 
3032 void PSParallelCompact::update_deferred_objects(ParCompactionManager* cm,
3033                                                 SpaceId id) {
3034   assert(id < last_space_id, "bad space id");
3035 
3036   ParallelCompactData& sd = summary_data();
3037   const SpaceInfo* const space_info = _space_info + id;
3038   ObjectStartArray* const start_array = space_info->start_array();
3039 
3040   const MutableSpace* const space = space_info->space();
3041   assert(space_info->dense_prefix() >= space->bottom(), "dense_prefix not set");
3042   HeapWord* const beg_addr = space_info->dense_prefix();
3043   HeapWord* const end_addr = sd.region_align_up(space_info->new_top());
3044 
3045   const RegionData* const beg_region = sd.addr_to_region_ptr(beg_addr);
3046   const RegionData* const end_region = sd.addr_to_region_ptr(end_addr);
3047   const RegionData* cur_region;
3048   for (cur_region = beg_region; cur_region < end_region; ++cur_region) {
3049     HeapWord* const addr = cur_region->deferred_obj_addr();
3050     if (addr != NULL) {
3051       if (start_array != NULL) {
3052         start_array->allocate_block(addr);
3053       }
3054       oop(addr)->update_contents(cm);
3055       assert(oop(addr)->is_oop_or_null(), "should be an oop now");
3056     }
3057   }
3058 }
3059 
3060 // Skip over count live words starting from beg, and return the address of the
3061 // next live word.  Unless marked, the word corresponding to beg is assumed to
3062 // be dead.  Callers must either ensure beg does not correspond to the middle of
3063 // an object, or account for those live words in some other way.  Callers must
3064 // also ensure that there are enough live words in the range [beg, end) to skip.
3065 HeapWord*
3066 PSParallelCompact::skip_live_words(HeapWord* beg, HeapWord* end, size_t count)
3067 {
3068   assert(count > 0, "sanity");
3069 
3070   ParMarkBitMap* m = mark_bitmap();
3071   idx_t bits_to_skip = m->words_to_bits(count);
3072   idx_t cur_beg = m->addr_to_bit(beg);
3073   const idx_t search_end = BitMap::word_align_up(m->addr_to_bit(end));
3074 
3075   do {
3076     cur_beg = m->find_obj_beg(cur_beg, search_end);
3077     idx_t cur_end = m->find_obj_end(cur_beg, search_end);
3078     const size_t obj_bits = cur_end - cur_beg + 1;
3079     if (obj_bits > bits_to_skip) {
3080       return m->bit_to_addr(cur_beg + bits_to_skip);
3081     }
3082     bits_to_skip -= obj_bits;
3083     cur_beg = cur_end + 1;
3084   } while (bits_to_skip > 0);
3085 
3086   // Skipping the desired number of words landed just past the end of an object.
3087   // Find the start of the next object.
3088   cur_beg = m->find_obj_beg(cur_beg, search_end);
3089   assert(cur_beg < m->addr_to_bit(end), "not enough live words to skip");
3090   return m->bit_to_addr(cur_beg);
3091 }
3092 
3093 HeapWord* PSParallelCompact::first_src_addr(HeapWord* const dest_addr,
3094                                             SpaceId src_space_id,
3095                                             size_t src_region_idx)
3096 {
3097   assert(summary_data().is_region_aligned(dest_addr), "not aligned");
3098 
3099   const SplitInfo& split_info = _space_info[src_space_id].split_info();
3100   if (split_info.dest_region_addr() == dest_addr) {
3101     // The partial object ending at the split point contains the first word to
3102     // be copied to dest_addr.
3103     return split_info.first_src_addr();
3104   }
3105 
3106   const ParallelCompactData& sd = summary_data();
3107   ParMarkBitMap* const bitmap = mark_bitmap();
3108   const size_t RegionSize = ParallelCompactData::RegionSize;
3109 
3110   assert(sd.is_region_aligned(dest_addr), "not aligned");
3111   const RegionData* const src_region_ptr = sd.region(src_region_idx);
3112   const size_t partial_obj_size = src_region_ptr->partial_obj_size();
3113   HeapWord* const src_region_destination = src_region_ptr->destination();
3114 
3115   assert(dest_addr >= src_region_destination, "wrong src region");
3116   assert(src_region_ptr->data_size() > 0, "src region cannot be empty");
3117 
3118   HeapWord* const src_region_beg = sd.region_to_addr(src_region_idx);
3119   HeapWord* const src_region_end = src_region_beg + RegionSize;
3120 
3121   HeapWord* addr = src_region_beg;
3122   if (dest_addr == src_region_destination) {
3123     // Return the first live word in the source region.
3124     if (partial_obj_size == 0) {
3125       addr = bitmap->find_obj_beg(addr, src_region_end);
3126       assert(addr < src_region_end, "no objects start in src region");
3127     }
3128     return addr;
3129   }
3130 
3131   // Must skip some live data.
3132   size_t words_to_skip = dest_addr - src_region_destination;
3133   assert(src_region_ptr->data_size() > words_to_skip, "wrong src region");
3134 
3135   if (partial_obj_size >= words_to_skip) {
3136     // All the live words to skip are part of the partial object.
3137     addr += words_to_skip;
3138     if (partial_obj_size == words_to_skip) {
3139       // Find the first live word past the partial object.
3140       addr = bitmap->find_obj_beg(addr, src_region_end);
3141       assert(addr < src_region_end, "wrong src region");
3142     }
3143     return addr;
3144   }
3145 
3146   // Skip over the partial object (if any).
3147   if (partial_obj_size != 0) {
3148     words_to_skip -= partial_obj_size;
3149     addr += partial_obj_size;
3150   }
3151 
3152   // Skip over live words due to objects that start in the region.
3153   addr = skip_live_words(addr, src_region_end, words_to_skip);
3154   assert(addr < src_region_end, "wrong src region");
3155   return addr;
3156 }
3157 
3158 void PSParallelCompact::decrement_destination_counts(ParCompactionManager* cm,
3159                                                      SpaceId src_space_id,
3160                                                      size_t beg_region,
3161                                                      HeapWord* end_addr)
3162 {
3163   ParallelCompactData& sd = summary_data();
3164 
3165 #ifdef ASSERT
3166   MutableSpace* const src_space = _space_info[src_space_id].space();
3167   HeapWord* const beg_addr = sd.region_to_addr(beg_region);
3168   assert(src_space->contains(beg_addr) || beg_addr == src_space->end(),
3169          "src_space_id does not match beg_addr");
3170   assert(src_space->contains(end_addr) || end_addr == src_space->end(),
3171          "src_space_id does not match end_addr");
3172 #endif // #ifdef ASSERT
3173 
3174   RegionData* const beg = sd.region(beg_region);
3175   RegionData* const end = sd.addr_to_region_ptr(sd.region_align_up(end_addr));
3176 
3177   // Regions up to new_top() are enqueued if they become available.
3178   HeapWord* const new_top = _space_info[src_space_id].new_top();
3179   RegionData* const enqueue_end =
3180     sd.addr_to_region_ptr(sd.region_align_up(new_top));
3181 
3182   for (RegionData* cur = beg; cur < end; ++cur) {
3183     assert(cur->data_size() > 0, "region must have live data");
3184     cur->decrement_destination_count();
3185     if (cur < enqueue_end && cur->available() && cur->claim()) {
3186       cm->push_region(sd.region(cur));
3187     }
3188   }
3189 }
3190 
3191 size_t PSParallelCompact::next_src_region(MoveAndUpdateClosure& closure,
3192                                           SpaceId& src_space_id,
3193                                           HeapWord*& src_space_top,
3194                                           HeapWord* end_addr)
3195 {
3196   typedef ParallelCompactData::RegionData RegionData;
3197 
3198   ParallelCompactData& sd = PSParallelCompact::summary_data();
3199   const size_t region_size = ParallelCompactData::RegionSize;
3200 
3201   size_t src_region_idx = 0;
3202 
3203   // Skip empty regions (if any) up to the top of the space.
3204   HeapWord* const src_aligned_up = sd.region_align_up(end_addr);
3205   RegionData* src_region_ptr = sd.addr_to_region_ptr(src_aligned_up);
3206   HeapWord* const top_aligned_up = sd.region_align_up(src_space_top);
3207   const RegionData* const top_region_ptr =
3208     sd.addr_to_region_ptr(top_aligned_up);
3209   while (src_region_ptr < top_region_ptr && src_region_ptr->data_size() == 0) {
3210     ++src_region_ptr;
3211   }
3212 
3213   if (src_region_ptr < top_region_ptr) {
3214     // The next source region is in the current space.  Update src_region_idx
3215     // and the source address to match src_region_ptr.
3216     src_region_idx = sd.region(src_region_ptr);
3217     HeapWord* const src_region_addr = sd.region_to_addr(src_region_idx);
3218     if (src_region_addr > closure.source()) {
3219       closure.set_source(src_region_addr);
3220     }
3221     return src_region_idx;
3222   }
3223 
3224   // Switch to a new source space and find the first non-empty region.
3225   unsigned int space_id = src_space_id + 1;
3226   assert(space_id < last_space_id, "not enough spaces");
3227 
3228   HeapWord* const destination = closure.destination();
3229 
3230   do {
3231     MutableSpace* space = _space_info[space_id].space();
3232     HeapWord* const bottom = space->bottom();
3233     const RegionData* const bottom_cp = sd.addr_to_region_ptr(bottom);
3234 
3235     // Iterate over the spaces that do not compact into themselves.
3236     if (bottom_cp->destination() != bottom) {
3237       HeapWord* const top_aligned_up = sd.region_align_up(space->top());
3238       const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
3239 
3240       for (const RegionData* src_cp = bottom_cp; src_cp < top_cp; ++src_cp) {
3241         if (src_cp->live_obj_size() > 0) {
3242           // Found it.
3243           assert(src_cp->destination() == destination,
3244                  "first live obj in the space must match the destination");
3245           assert(src_cp->partial_obj_size() == 0,
3246                  "a space cannot begin with a partial obj");
3247 
3248           src_space_id = SpaceId(space_id);
3249           src_space_top = space->top();
3250           const size_t src_region_idx = sd.region(src_cp);
3251           closure.set_source(sd.region_to_addr(src_region_idx));
3252           return src_region_idx;
3253         } else {
3254           assert(src_cp->data_size() == 0, "sanity");
3255         }
3256       }
3257     }
3258   } while (++space_id < last_space_id);
3259 
3260   assert(false, "no source region was found");
3261   return 0;
3262 }
3263 
3264 void PSParallelCompact::fill_region(ParCompactionManager* cm, size_t region_idx)
3265 {
3266   typedef ParMarkBitMap::IterationStatus IterationStatus;
3267   const size_t RegionSize = ParallelCompactData::RegionSize;
3268   ParMarkBitMap* const bitmap = mark_bitmap();
3269   ParallelCompactData& sd = summary_data();
3270   RegionData* const region_ptr = sd.region(region_idx);
3271 
3272   // Get the items needed to construct the closure.
3273   HeapWord* dest_addr = sd.region_to_addr(region_idx);
3274   SpaceId dest_space_id = space_id(dest_addr);
3275   ObjectStartArray* start_array = _space_info[dest_space_id].start_array();
3276   HeapWord* new_top = _space_info[dest_space_id].new_top();
3277   assert(dest_addr < new_top, "sanity");
3278   const size_t words = MIN2(pointer_delta(new_top, dest_addr), RegionSize);
3279 
3280   // Get the source region and related info.
3281   size_t src_region_idx = region_ptr->source_region();
3282   SpaceId src_space_id = space_id(sd.region_to_addr(src_region_idx));
3283   HeapWord* src_space_top = _space_info[src_space_id].space()->top();
3284 
3285   MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words);
3286   closure.set_source(first_src_addr(dest_addr, src_space_id, src_region_idx));
3287 
3288   // Adjust src_region_idx to prepare for decrementing destination counts (the
3289   // destination count is not decremented when a region is copied to itself).
3290   if (src_region_idx == region_idx) {
3291     src_region_idx += 1;
3292   }
3293 
3294   if (bitmap->is_unmarked(closure.source())) {
3295     // The first source word is in the middle of an object; copy the remainder
3296     // of the object or as much as will fit.  The fact that pointer updates were
3297     // deferred will be noted when the object header is processed.
3298     HeapWord* const old_src_addr = closure.source();
3299     closure.copy_partial_obj();
3300     if (closure.is_full()) {
3301       decrement_destination_counts(cm, src_space_id, src_region_idx,
3302                                    closure.source());
3303       region_ptr->set_deferred_obj_addr(NULL);
3304       region_ptr->set_completed();
3305       return;
3306     }
3307 
3308     HeapWord* const end_addr = sd.region_align_down(closure.source());
3309     if (sd.region_align_down(old_src_addr) != end_addr) {
3310       // The partial object was copied from more than one source region.
3311       decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
3312 
3313       // Move to the next source region, possibly switching spaces as well.  All
3314       // args except end_addr may be modified.
3315       src_region_idx = next_src_region(closure, src_space_id, src_space_top,
3316                                        end_addr);
3317     }
3318   }
3319 
3320   do {
3321     HeapWord* const cur_addr = closure.source();
3322     HeapWord* const end_addr = MIN2(sd.region_align_up(cur_addr + 1),
3323                                     src_space_top);
3324     IterationStatus status = bitmap->iterate(&closure, cur_addr, end_addr);
3325 
3326     if (status == ParMarkBitMap::incomplete) {
3327       // The last obj that starts in the source region does not end in the
3328       // region.
3329       assert(closure.source() < end_addr, "sanity");
3330       HeapWord* const obj_beg = closure.source();
3331       HeapWord* const range_end = MIN2(obj_beg + closure.words_remaining(),
3332                                        src_space_top);
3333       HeapWord* const obj_end = bitmap->find_obj_end(obj_beg, range_end);
3334       if (obj_end < range_end) {
3335         // The end was found; the entire object will fit.
3336         status = closure.do_addr(obj_beg, bitmap->obj_size(obj_beg, obj_end));
3337         assert(status != ParMarkBitMap::would_overflow, "sanity");
3338       } else {
3339         // The end was not found; the object will not fit.
3340         assert(range_end < src_space_top, "obj cannot cross space boundary");
3341         status = ParMarkBitMap::would_overflow;
3342       }
3343     }
3344 
3345     if (status == ParMarkBitMap::would_overflow) {
3346       // The last object did not fit.  Note that interior oop updates were
3347       // deferred, then copy enough of the object to fill the region.
3348       region_ptr->set_deferred_obj_addr(closure.destination());
3349       status = closure.copy_until_full(); // copies from closure.source()
3350 
3351       decrement_destination_counts(cm, src_space_id, src_region_idx,
3352                                    closure.source());
3353       region_ptr->set_completed();
3354       return;
3355     }
3356 
3357     if (status == ParMarkBitMap::full) {
3358       decrement_destination_counts(cm, src_space_id, src_region_idx,
3359                                    closure.source());
3360       region_ptr->set_deferred_obj_addr(NULL);
3361       region_ptr->set_completed();
3362       return;
3363     }
3364 
3365     decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
3366 
3367     // Move to the next source region, possibly switching spaces as well.  All
3368     // args except end_addr may be modified.
3369     src_region_idx = next_src_region(closure, src_space_id, src_space_top,
3370                                      end_addr);
3371   } while (true);
3372 }
3373 
3374 void
3375 PSParallelCompact::move_and_update(ParCompactionManager* cm, SpaceId space_id) {
3376   const MutableSpace* sp = space(space_id);
3377   if (sp->is_empty()) {
3378     return;
3379   }
3380 
3381   ParallelCompactData& sd = PSParallelCompact::summary_data();
3382   ParMarkBitMap* const bitmap = mark_bitmap();
3383   HeapWord* const dp_addr = dense_prefix(space_id);
3384   HeapWord* beg_addr = sp->bottom();
3385   HeapWord* end_addr = sp->top();
3386 
3387   assert(beg_addr <= dp_addr && dp_addr <= end_addr, "bad dense prefix");
3388 
3389   const size_t beg_region = sd.addr_to_region_idx(beg_addr);
3390   const size_t dp_region = sd.addr_to_region_idx(dp_addr);
3391   if (beg_region < dp_region) {
3392     update_and_deadwood_in_dense_prefix(cm, space_id, beg_region, dp_region);
3393   }
3394 
3395   // The destination of the first live object that starts in the region is one
3396   // past the end of the partial object entering the region (if any).
3397   HeapWord* const dest_addr = sd.partial_obj_end(dp_region);
3398   HeapWord* const new_top = _space_info[space_id].new_top();
3399   assert(new_top >= dest_addr, "bad new_top value");
3400   const size_t words = pointer_delta(new_top, dest_addr);
3401 
3402   if (words > 0) {
3403     ObjectStartArray* start_array = _space_info[space_id].start_array();
3404     MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words);
3405 
3406     ParMarkBitMap::IterationStatus status;
3407     status = bitmap->iterate(&closure, dest_addr, end_addr);
3408     assert(status == ParMarkBitMap::full, "iteration not complete");
3409     assert(bitmap->find_obj_beg(closure.source(), end_addr) == end_addr,
3410            "live objects skipped because closure is full");
3411   }
3412 }
3413 
3414 jlong PSParallelCompact::millis_since_last_gc() {
3415   // We need a monotonically non-deccreasing time in ms but
3416   // os::javaTimeMillis() does not guarantee monotonicity.
3417   jlong now = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
3418   jlong ret_val = now - _time_of_last_gc;
3419   // XXX See note in genCollectedHeap::millis_since_last_gc().
3420   if (ret_val < 0) {
3421     NOT_PRODUCT(warning("time warp: "INT64_FORMAT, ret_val);)
3422     return 0;
3423   }
3424   return ret_val;
3425 }
3426 
3427 void PSParallelCompact::reset_millis_since_last_gc() {
3428   // We need a monotonically non-deccreasing time in ms but
3429   // os::javaTimeMillis() does not guarantee monotonicity.
3430   _time_of_last_gc = os::javaTimeNanos() / NANOSECS_PER_MILLISEC;
3431 }
3432 
3433 ParMarkBitMap::IterationStatus MoveAndUpdateClosure::copy_until_full()
3434 {
3435   if (source() != destination()) {
3436     DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3437     Copy::aligned_conjoint_words(source(), destination(), words_remaining());
3438   }
3439   update_state(words_remaining());
3440   assert(is_full(), "sanity");
3441   return ParMarkBitMap::full;
3442 }
3443 
3444 void MoveAndUpdateClosure::copy_partial_obj()
3445 {
3446   size_t words = words_remaining();
3447 
3448   HeapWord* const range_end = MIN2(source() + words, bitmap()->region_end());
3449   HeapWord* const end_addr = bitmap()->find_obj_end(source(), range_end);
3450   if (end_addr < range_end) {
3451     words = bitmap()->obj_size(source(), end_addr);
3452   }
3453 
3454   // This test is necessary; if omitted, the pointer updates to a partial object
3455   // that crosses the dense prefix boundary could be overwritten.
3456   if (source() != destination()) {
3457     DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3458     Copy::aligned_conjoint_words(source(), destination(), words);
3459   }
3460   update_state(words);
3461 }
3462 
3463 ParMarkBitMapClosure::IterationStatus
3464 MoveAndUpdateClosure::do_addr(HeapWord* addr, size_t words) {
3465   assert(destination() != NULL, "sanity");
3466   assert(bitmap()->obj_size(addr) == words, "bad size");
3467 
3468   _source = addr;
3469   assert(PSParallelCompact::summary_data().calc_new_pointer(source()) ==
3470          destination(), "wrong destination");
3471 
3472   if (words > words_remaining()) {
3473     return ParMarkBitMap::would_overflow;
3474   }
3475 
3476   // The start_array must be updated even if the object is not moving.
3477   if (_start_array != NULL) {
3478     _start_array->allocate_block(destination());
3479   }
3480 
3481   if (destination() != source()) {
3482     DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3483     Copy::aligned_conjoint_words(source(), destination(), words);
3484   }
3485 
3486   oop moved_oop = (oop) destination();
3487   moved_oop->update_contents(compaction_manager());
3488   assert(moved_oop->is_oop_or_null(), "Object should be whole at this point");
3489 
3490   update_state(words);
3491   assert(destination() == (HeapWord*)moved_oop + moved_oop->size(), "sanity");
3492   return is_full() ? ParMarkBitMap::full : ParMarkBitMap::incomplete;
3493 }
3494 
3495 UpdateOnlyClosure::UpdateOnlyClosure(ParMarkBitMap* mbm,
3496                                      ParCompactionManager* cm,
3497                                      PSParallelCompact::SpaceId space_id) :
3498   ParMarkBitMapClosure(mbm, cm),
3499   _space_id(space_id),
3500   _start_array(PSParallelCompact::start_array(space_id))
3501 {
3502 }
3503 
3504 // Updates the references in the object to their new values.
3505 ParMarkBitMapClosure::IterationStatus
3506 UpdateOnlyClosure::do_addr(HeapWord* addr, size_t words) {
3507   do_addr(addr);
3508   return ParMarkBitMap::incomplete;
3509 }
3510 
3511 // Prepare for compaction.  This method is executed once
3512 // (i.e., by a single thread) before compaction.
3513 // Save the updated location of the intArrayKlassObj for
3514 // filling holes in the dense prefix.
3515 void PSParallelCompact::compact_prologue() {
3516   _updated_int_array_klass_obj = (klassOop)
3517     summary_data().calc_new_pointer(Universe::intArrayKlassObj());
3518 }