1 /*
   2  * Copyright 2005-2009 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  20  * CA 95054 USA or visit www.sun.com if you need additional information or
  21  * have any questions.
  22  *
  23  */
  24 
  25 #include "incls/_precompiled.incl"
  26 #include "incls/_psParallelCompact.cpp.incl"
  27 
  28 #include <math.h>
  29 
  30 // All sizes are in HeapWords.
  31 const size_t ParallelCompactData::Log2RegionSize  = 9; // 512 words
  32 const size_t ParallelCompactData::RegionSize      = (size_t)1 << Log2RegionSize;
  33 const size_t ParallelCompactData::RegionSizeBytes =
  34   RegionSize << LogHeapWordSize;
  35 const size_t ParallelCompactData::RegionSizeOffsetMask = RegionSize - 1;
  36 const size_t ParallelCompactData::RegionAddrOffsetMask = RegionSizeBytes - 1;
  37 const size_t ParallelCompactData::RegionAddrMask  = ~RegionAddrOffsetMask;
  38 
  39 const ParallelCompactData::RegionData::region_sz_t
  40 ParallelCompactData::RegionData::dc_shift = 27;
  41 
  42 const ParallelCompactData::RegionData::region_sz_t
  43 ParallelCompactData::RegionData::dc_mask = ~0U << dc_shift;
  44 
  45 const ParallelCompactData::RegionData::region_sz_t
  46 ParallelCompactData::RegionData::dc_one = 0x1U << dc_shift;
  47 
  48 const ParallelCompactData::RegionData::region_sz_t
  49 ParallelCompactData::RegionData::los_mask = ~dc_mask;
  50 
  51 const ParallelCompactData::RegionData::region_sz_t
  52 ParallelCompactData::RegionData::dc_claimed = 0x8U << dc_shift;
  53 
  54 const ParallelCompactData::RegionData::region_sz_t
  55 ParallelCompactData::RegionData::dc_completed = 0xcU << dc_shift;
  56 
  57 SpaceInfo PSParallelCompact::_space_info[PSParallelCompact::last_space_id];
  58 bool      PSParallelCompact::_print_phases = false;
  59 
  60 ReferenceProcessor* PSParallelCompact::_ref_processor = NULL;
  61 klassOop            PSParallelCompact::_updated_int_array_klass_obj = NULL;
  62 
  63 double PSParallelCompact::_dwl_mean;
  64 double PSParallelCompact::_dwl_std_dev;
  65 double PSParallelCompact::_dwl_first_term;
  66 double PSParallelCompact::_dwl_adjustment;
  67 #ifdef  ASSERT
  68 bool   PSParallelCompact::_dwl_initialized = false;
  69 #endif  // #ifdef ASSERT
  70 
  71 #ifdef VALIDATE_MARK_SWEEP
  72 GrowableArray<void*>*   PSParallelCompact::_root_refs_stack = NULL;
  73 GrowableArray<oop> *    PSParallelCompact::_live_oops = NULL;
  74 GrowableArray<oop> *    PSParallelCompact::_live_oops_moved_to = NULL;
  75 GrowableArray<size_t>*  PSParallelCompact::_live_oops_size = NULL;
  76 size_t                  PSParallelCompact::_live_oops_index = 0;
  77 size_t                  PSParallelCompact::_live_oops_index_at_perm = 0;
  78 GrowableArray<void*>*   PSParallelCompact::_other_refs_stack = NULL;
  79 GrowableArray<void*>*   PSParallelCompact::_adjusted_pointers = NULL;
  80 bool                    PSParallelCompact::_pointer_tracking = false;
  81 bool                    PSParallelCompact::_root_tracking = true;
  82 
  83 GrowableArray<HeapWord*>* PSParallelCompact::_cur_gc_live_oops = NULL;
  84 GrowableArray<HeapWord*>* PSParallelCompact::_cur_gc_live_oops_moved_to = NULL;
  85 GrowableArray<size_t>   * PSParallelCompact::_cur_gc_live_oops_size = NULL;
  86 GrowableArray<HeapWord*>* PSParallelCompact::_last_gc_live_oops = NULL;
  87 GrowableArray<HeapWord*>* PSParallelCompact::_last_gc_live_oops_moved_to = NULL;
  88 GrowableArray<size_t>   * PSParallelCompact::_last_gc_live_oops_size = NULL;
  89 #endif
  90 
  91 void SplitInfo::record(size_t src_region_idx, size_t partial_obj_size,
  92                        HeapWord* destination)
  93 {
  94   assert(src_region_idx != 0, "invalid src_region_idx");
  95   assert(partial_obj_size != 0, "invalid partial_obj_size argument");
  96   assert(destination != NULL, "invalid destination argument");
  97 
  98   _src_region_idx = src_region_idx;
  99   _partial_obj_size = partial_obj_size;
 100   _destination = destination;
 101 
 102   // These fields may not be updated below, so make sure they're clear.
 103   assert(_dest_region_addr == NULL, "should have been cleared");
 104   assert(_first_src_addr == NULL, "should have been cleared");
 105 
 106   // Determine the number of destination regions for the partial object.
 107   HeapWord* const last_word = destination + partial_obj_size - 1;
 108   const ParallelCompactData& sd = PSParallelCompact::summary_data();
 109   HeapWord* const beg_region_addr = sd.region_align_down(destination);
 110   HeapWord* const end_region_addr = sd.region_align_down(last_word);
 111 
 112   if (beg_region_addr == end_region_addr) {
 113     // One destination region.
 114     _destination_count = 1;
 115     if (end_region_addr == destination) {
 116       // The destination falls on a region boundary, thus the first word of the
 117       // partial object will be the first word copied to the destination region.
 118       _dest_region_addr = end_region_addr;
 119       _first_src_addr = sd.region_to_addr(src_region_idx);
 120     }
 121   } else {
 122     // Two destination regions.  When copied, the partial object will cross a
 123     // destination region boundary, so a word somewhere within the partial
 124     // object will be the first word copied to the second destination region.
 125     _destination_count = 2;
 126     _dest_region_addr = end_region_addr;
 127     const size_t ofs = pointer_delta(end_region_addr, destination);
 128     assert(ofs < _partial_obj_size, "sanity");
 129     _first_src_addr = sd.region_to_addr(src_region_idx) + ofs;
 130   }
 131 }
 132 
 133 void SplitInfo::clear()
 134 {
 135   _src_region_idx = 0;
 136   _partial_obj_size = 0;
 137   _destination = NULL;
 138   _destination_count = 0;
 139   _dest_region_addr = NULL;
 140   _first_src_addr = NULL;
 141   assert(!is_valid(), "sanity");
 142 }
 143 
 144 #ifdef  ASSERT
 145 void SplitInfo::verify_clear()
 146 {
 147   assert(_src_region_idx == 0, "not clear");
 148   assert(_partial_obj_size == 0, "not clear");
 149   assert(_destination == NULL, "not clear");
 150   assert(_destination_count == 0, "not clear");
 151   assert(_dest_region_addr == NULL, "not clear");
 152   assert(_first_src_addr == NULL, "not clear");
 153 }
 154 #endif  // #ifdef ASSERT
 155 
 156 
 157 #ifndef PRODUCT
 158 const char* PSParallelCompact::space_names[] = {
 159   "perm", "old ", "eden", "from", "to  "
 160 };
 161 
 162 void PSParallelCompact::print_region_ranges()
 163 {
 164   tty->print_cr("space  bottom     top        end        new_top");
 165   tty->print_cr("------ ---------- ---------- ---------- ----------");
 166 
 167   for (unsigned int id = 0; id < last_space_id; ++id) {
 168     const MutableSpace* space = _space_info[id].space();
 169     tty->print_cr("%u %s "
 170                   SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " "
 171                   SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10) " ",
 172                   id, space_names[id],
 173                   summary_data().addr_to_region_idx(space->bottom()),
 174                   summary_data().addr_to_region_idx(space->top()),
 175                   summary_data().addr_to_region_idx(space->end()),
 176                   summary_data().addr_to_region_idx(_space_info[id].new_top()));
 177   }
 178 }
 179 
 180 void
 181 print_generic_summary_region(size_t i, const ParallelCompactData::RegionData* c)
 182 {
 183 #define REGION_IDX_FORMAT        SIZE_FORMAT_W(7)
 184 #define REGION_DATA_FORMAT       SIZE_FORMAT_W(5)
 185 
 186   ParallelCompactData& sd = PSParallelCompact::summary_data();
 187   size_t dci = c->destination() ? sd.addr_to_region_idx(c->destination()) : 0;
 188   tty->print_cr(REGION_IDX_FORMAT " " PTR_FORMAT " "
 189                 REGION_IDX_FORMAT " " PTR_FORMAT " "
 190                 REGION_DATA_FORMAT " " REGION_DATA_FORMAT " "
 191                 REGION_DATA_FORMAT " " REGION_IDX_FORMAT " %d",
 192                 i, c->data_location(), dci, c->destination(),
 193                 c->partial_obj_size(), c->live_obj_size(),
 194                 c->data_size(), c->source_region(), c->destination_count());
 195 
 196 #undef  REGION_IDX_FORMAT
 197 #undef  REGION_DATA_FORMAT
 198 }
 199 
 200 void
 201 print_generic_summary_data(ParallelCompactData& summary_data,
 202                            HeapWord* const beg_addr,
 203                            HeapWord* const end_addr)
 204 {
 205   size_t total_words = 0;
 206   size_t i = summary_data.addr_to_region_idx(beg_addr);
 207   const size_t last = summary_data.addr_to_region_idx(end_addr);
 208   HeapWord* pdest = 0;
 209 
 210   while (i <= last) {
 211     ParallelCompactData::RegionData* c = summary_data.region(i);
 212     if (c->data_size() != 0 || c->destination() != pdest) {
 213       print_generic_summary_region(i, c);
 214       total_words += c->data_size();
 215       pdest = c->destination();
 216     }
 217     ++i;
 218   }
 219 
 220   tty->print_cr("summary_data_bytes=" SIZE_FORMAT, total_words * HeapWordSize);
 221 }
 222 
 223 void
 224 print_generic_summary_data(ParallelCompactData& summary_data,
 225                            SpaceInfo* space_info)
 226 {
 227   for (unsigned int id = 0; id < PSParallelCompact::last_space_id; ++id) {
 228     const MutableSpace* space = space_info[id].space();
 229     print_generic_summary_data(summary_data, space->bottom(),
 230                                MAX2(space->top(), space_info[id].new_top()));
 231   }
 232 }
 233 
 234 void
 235 print_initial_summary_region(size_t i,
 236                              const ParallelCompactData::RegionData* c,
 237                              bool newline = true)
 238 {
 239   tty->print(SIZE_FORMAT_W(5) " " PTR_FORMAT " "
 240              SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " "
 241              SIZE_FORMAT_W(5) " " SIZE_FORMAT_W(5) " %d",
 242              i, c->destination(),
 243              c->partial_obj_size(), c->live_obj_size(),
 244              c->data_size(), c->source_region(), c->destination_count());
 245   if (newline) tty->cr();
 246 }
 247 
 248 void
 249 print_initial_summary_data(ParallelCompactData& summary_data,
 250                            const MutableSpace* space) {
 251   if (space->top() == space->bottom()) {
 252     return;
 253   }
 254 
 255   const size_t region_size = ParallelCompactData::RegionSize;
 256   typedef ParallelCompactData::RegionData RegionData;
 257   HeapWord* const top_aligned_up = summary_data.region_align_up(space->top());
 258   const size_t end_region = summary_data.addr_to_region_idx(top_aligned_up);
 259   const RegionData* c = summary_data.region(end_region - 1);
 260   HeapWord* end_addr = c->destination() + c->data_size();
 261   const size_t live_in_space = pointer_delta(end_addr, space->bottom());
 262 
 263   // Print (and count) the full regions at the beginning of the space.
 264   size_t full_region_count = 0;
 265   size_t i = summary_data.addr_to_region_idx(space->bottom());
 266   while (i < end_region && summary_data.region(i)->data_size() == region_size) {
 267     print_initial_summary_region(i, summary_data.region(i));
 268     ++full_region_count;
 269     ++i;
 270   }
 271 
 272   size_t live_to_right = live_in_space - full_region_count * region_size;
 273 
 274   double max_reclaimed_ratio = 0.0;
 275   size_t max_reclaimed_ratio_region = 0;
 276   size_t max_dead_to_right = 0;
 277   size_t max_live_to_right = 0;
 278 
 279   // Print the 'reclaimed ratio' for regions while there is something live in
 280   // the region or to the right of it.  The remaining regions are empty (and
 281   // uninteresting), and computing the ratio will result in division by 0.
 282   while (i < end_region && live_to_right > 0) {
 283     c = summary_data.region(i);
 284     HeapWord* const region_addr = summary_data.region_to_addr(i);
 285     const size_t used_to_right = pointer_delta(space->top(), region_addr);
 286     const size_t dead_to_right = used_to_right - live_to_right;
 287     const double reclaimed_ratio = double(dead_to_right) / live_to_right;
 288 
 289     if (reclaimed_ratio > max_reclaimed_ratio) {
 290             max_reclaimed_ratio = reclaimed_ratio;
 291             max_reclaimed_ratio_region = i;
 292             max_dead_to_right = dead_to_right;
 293             max_live_to_right = live_to_right;
 294     }
 295 
 296     print_initial_summary_region(i, c, false);
 297     tty->print_cr(" %12.10f " SIZE_FORMAT_W(10) " " SIZE_FORMAT_W(10),
 298                   reclaimed_ratio, dead_to_right, live_to_right);
 299 
 300     live_to_right -= c->data_size();
 301     ++i;
 302   }
 303 
 304   // Any remaining regions are empty.  Print one more if there is one.
 305   if (i < end_region) {
 306     print_initial_summary_region(i, summary_data.region(i));
 307   }
 308 
 309   tty->print_cr("max:  " SIZE_FORMAT_W(4) " d2r=" SIZE_FORMAT_W(10) " "
 310                 "l2r=" SIZE_FORMAT_W(10) " max_ratio=%14.12f",
 311                 max_reclaimed_ratio_region, max_dead_to_right,
 312                 max_live_to_right, max_reclaimed_ratio);
 313 }
 314 
 315 void
 316 print_initial_summary_data(ParallelCompactData& summary_data,
 317                            SpaceInfo* space_info) {
 318   unsigned int id = PSParallelCompact::perm_space_id;
 319   const MutableSpace* space;
 320   do {
 321     space = space_info[id].space();
 322     print_initial_summary_data(summary_data, space);
 323   } while (++id < PSParallelCompact::eden_space_id);
 324 
 325   do {
 326     space = space_info[id].space();
 327     print_generic_summary_data(summary_data, space->bottom(), space->top());
 328   } while (++id < PSParallelCompact::last_space_id);
 329 }
 330 #endif  // #ifndef PRODUCT
 331 
 332 #ifdef  ASSERT
 333 size_t add_obj_count;
 334 size_t add_obj_size;
 335 size_t mark_bitmap_count;
 336 size_t mark_bitmap_size;
 337 #endif  // #ifdef ASSERT
 338 
 339 ParallelCompactData::ParallelCompactData()
 340 {
 341   _region_start = 0;
 342 
 343   _region_vspace = 0;
 344   _region_data = 0;
 345   _region_count = 0;
 346 }
 347 
 348 bool ParallelCompactData::initialize(MemRegion covered_region)
 349 {
 350   _region_start = covered_region.start();
 351   const size_t region_size = covered_region.word_size();
 352   DEBUG_ONLY(_region_end = _region_start + region_size;)
 353 
 354   assert(region_align_down(_region_start) == _region_start,
 355          "region start not aligned");
 356   assert((region_size & RegionSizeOffsetMask) == 0,
 357          "region size not a multiple of RegionSize");
 358 
 359   bool result = initialize_region_data(region_size);
 360 
 361   return result;
 362 }
 363 
 364 PSVirtualSpace*
 365 ParallelCompactData::create_vspace(size_t count, size_t element_size)
 366 {
 367   const size_t raw_bytes = count * element_size;
 368   const size_t page_sz = os::page_size_for_region(raw_bytes, raw_bytes, 10);
 369   const size_t granularity = os::vm_allocation_granularity();
 370   const size_t bytes = align_size_up(raw_bytes, MAX2(page_sz, granularity));
 371 
 372   const size_t rs_align = page_sz == (size_t) os::vm_page_size() ? 0 :
 373     MAX2(page_sz, granularity);
 374   ReservedSpace rs(bytes, rs_align, rs_align > 0);
 375   os::trace_page_sizes("par compact", raw_bytes, raw_bytes, page_sz, rs.base(),
 376                        rs.size());
 377   PSVirtualSpace* vspace = new PSVirtualSpace(rs, page_sz);
 378   if (vspace != 0) {
 379     if (vspace->expand_by(bytes)) {
 380       return vspace;
 381     }
 382     delete vspace;
 383     // Release memory reserved in the space.
 384     rs.release();
 385   }
 386 
 387   return 0;
 388 }
 389 
 390 bool ParallelCompactData::initialize_region_data(size_t region_size)
 391 {
 392   const size_t count = (region_size + RegionSizeOffsetMask) >> Log2RegionSize;
 393   _region_vspace = create_vspace(count, sizeof(RegionData));
 394   if (_region_vspace != 0) {
 395     _region_data = (RegionData*)_region_vspace->reserved_low_addr();
 396     _region_count = count;
 397     return true;
 398   }
 399   return false;
 400 }
 401 
 402 void ParallelCompactData::clear()
 403 {
 404   memset(_region_data, 0, _region_vspace->committed_size());
 405 }
 406 
 407 void ParallelCompactData::clear_range(size_t beg_region, size_t end_region) {
 408   assert(beg_region <= _region_count, "beg_region out of range");
 409   assert(end_region <= _region_count, "end_region out of range");
 410 
 411   const size_t region_cnt = end_region - beg_region;
 412   memset(_region_data + beg_region, 0, region_cnt * sizeof(RegionData));
 413 }
 414 
 415 HeapWord* ParallelCompactData::partial_obj_end(size_t region_idx) const
 416 {
 417   const RegionData* cur_cp = region(region_idx);
 418   const RegionData* const end_cp = region(region_count() - 1);
 419 
 420   HeapWord* result = region_to_addr(region_idx);
 421   if (cur_cp < end_cp) {
 422     do {
 423       result += cur_cp->partial_obj_size();
 424     } while (cur_cp->partial_obj_size() == RegionSize && ++cur_cp < end_cp);
 425   }
 426   return result;
 427 }
 428 
 429 void ParallelCompactData::add_obj(HeapWord* addr, size_t len)
 430 {
 431   const size_t obj_ofs = pointer_delta(addr, _region_start);
 432   const size_t beg_region = obj_ofs >> Log2RegionSize;
 433   const size_t end_region = (obj_ofs + len - 1) >> Log2RegionSize;
 434 
 435   DEBUG_ONLY(Atomic::inc_ptr(&add_obj_count);)
 436   DEBUG_ONLY(Atomic::add_ptr(len, &add_obj_size);)
 437 
 438   if (beg_region == end_region) {
 439     // All in one region.
 440     _region_data[beg_region].add_live_obj(len);
 441     return;
 442   }
 443 
 444   // First region.
 445   const size_t beg_ofs = region_offset(addr);
 446   _region_data[beg_region].add_live_obj(RegionSize - beg_ofs);
 447 
 448   klassOop klass = ((oop)addr)->klass();
 449   // Middle regions--completely spanned by this object.
 450   for (size_t region = beg_region + 1; region < end_region; ++region) {
 451     _region_data[region].set_partial_obj_size(RegionSize);
 452     _region_data[region].set_partial_obj_addr(addr);
 453   }
 454 
 455   // Last region.
 456   const size_t end_ofs = region_offset(addr + len - 1);
 457   _region_data[end_region].set_partial_obj_size(end_ofs + 1);
 458   _region_data[end_region].set_partial_obj_addr(addr);
 459 }
 460 
 461 void
 462 ParallelCompactData::summarize_dense_prefix(HeapWord* beg, HeapWord* end)
 463 {
 464   assert(region_offset(beg) == 0, "not RegionSize aligned");
 465   assert(region_offset(end) == 0, "not RegionSize aligned");
 466 
 467   size_t cur_region = addr_to_region_idx(beg);
 468   const size_t end_region = addr_to_region_idx(end);
 469   HeapWord* addr = beg;
 470   while (cur_region < end_region) {
 471     _region_data[cur_region].set_destination(addr);
 472     _region_data[cur_region].set_destination_count(0);
 473     _region_data[cur_region].set_source_region(cur_region);
 474     _region_data[cur_region].set_data_location(addr);
 475 
 476     // Update live_obj_size so the region appears completely full.
 477     size_t live_size = RegionSize - _region_data[cur_region].partial_obj_size();
 478     _region_data[cur_region].set_live_obj_size(live_size);
 479 
 480     ++cur_region;
 481     addr += RegionSize;
 482   }
 483 }
 484 
 485 // Find the point at which a space can be split and, if necessary, record the
 486 // split point.
 487 //
 488 // If the current src region (which overflowed the destination space) doesn't
 489 // have a partial object, the split point is at the beginning of the current src
 490 // region (an "easy" split, no extra bookkeeping required).
 491 //
 492 // If the current src region has a partial object, the split point is in the
 493 // region where that partial object starts (call it the split_region).  If
 494 // split_region has a partial object, then the split point is just after that
 495 // partial object (a "hard" split where we have to record the split data and
 496 // zero the partial_obj_size field).  With a "hard" split, we know that the
 497 // partial_obj ends within split_region because the partial object that caused
 498 // the overflow starts in split_region.  If split_region doesn't have a partial
 499 // obj, then the split is at the beginning of split_region (another "easy"
 500 // split).
 501 HeapWord*
 502 ParallelCompactData::summarize_split_space(size_t src_region,
 503                                            SplitInfo& split_info,
 504                                            HeapWord* destination,
 505                                            HeapWord* target_end,
 506                                            HeapWord** target_next)
 507 {
 508   assert(destination <= target_end, "sanity");
 509   assert(destination + _region_data[src_region].data_size() > target_end,
 510     "region should not fit into target space");
 511   assert(is_region_aligned(target_end), "sanity");
 512 
 513   size_t split_region = src_region;
 514   HeapWord* split_destination = destination;
 515   size_t partial_obj_size = _region_data[src_region].partial_obj_size();
 516 
 517   if (destination + partial_obj_size > target_end) {
 518     // The split point is just after the partial object (if any) in the
 519     // src_region that contains the start of the object that overflowed the
 520     // destination space.
 521     //
 522     // Find the start of the "overflow" object and set split_region to the
 523     // region containing it.
 524     HeapWord* const overflow_obj = _region_data[src_region].partial_obj_addr();
 525     split_region = addr_to_region_idx(overflow_obj);
 526 
 527     // Clear the source_region field of all destination regions whose first word
 528     // came from data after the split point (a non-null source_region field
 529     // implies a region must be filled).
 530     //
 531     // An alternative to the simple loop below:  clear during post_compact(),
 532     // which uses memcpy instead of individual stores, and is easy to
 533     // parallelize.  (The downside is that it clears the entire RegionData
 534     // object as opposed to just one field.)
 535     //
 536     // post_compact() would have to clear the summary data up to the highest
 537     // address that was written during the summary phase, which would be
 538     //
 539     //         max(top, max(new_top, clear_top))
 540     //
 541     // where clear_top is a new field in SpaceInfo.  Would have to set clear_top
 542     // to target_end.
 543     const RegionData* const sr = region(split_region);
 544     const size_t beg_idx =
 545       addr_to_region_idx(region_align_up(sr->destination() +
 546                                          sr->partial_obj_size()));
 547     const size_t end_idx = addr_to_region_idx(target_end);
 548 
 549     if (TraceParallelOldGCSummaryPhase) {
 550         gclog_or_tty->print_cr("split:  clearing source_region field in ["
 551                                SIZE_FORMAT ", " SIZE_FORMAT ")",
 552                                beg_idx, end_idx);
 553     }
 554     for (size_t idx = beg_idx; idx < end_idx; ++idx) {
 555       _region_data[idx].set_source_region(0);
 556     }
 557 
 558     // Set split_destination and partial_obj_size to reflect the split region.
 559     split_destination = sr->destination();
 560     partial_obj_size = sr->partial_obj_size();
 561   }
 562 
 563   // The split is recorded only if a partial object extends onto the region.
 564   if (partial_obj_size != 0) {
 565     _region_data[split_region].set_partial_obj_size(0);
 566     split_info.record(split_region, partial_obj_size, split_destination);
 567   }
 568 
 569   // Setup the continuation addresses.
 570   *target_next = split_destination + partial_obj_size;
 571   HeapWord* const source_next = region_to_addr(split_region) + partial_obj_size;
 572 
 573   if (TraceParallelOldGCSummaryPhase) {
 574     const char * split_type = partial_obj_size == 0 ? "easy" : "hard";
 575     gclog_or_tty->print_cr("%s split:  src=" PTR_FORMAT " src_c=" SIZE_FORMAT
 576                            " pos=" SIZE_FORMAT,
 577                            split_type, source_next, split_region,
 578                            partial_obj_size);
 579     gclog_or_tty->print_cr("%s split:  dst=" PTR_FORMAT " dst_c=" SIZE_FORMAT
 580                            " tn=" PTR_FORMAT,
 581                            split_type, split_destination,
 582                            addr_to_region_idx(split_destination),
 583                            *target_next);
 584 
 585     if (partial_obj_size != 0) {
 586       HeapWord* const po_beg = split_info.destination();
 587       HeapWord* const po_end = po_beg + split_info.partial_obj_size();
 588       gclog_or_tty->print_cr("%s split:  "
 589                              "po_beg=" PTR_FORMAT " " SIZE_FORMAT " "
 590                              "po_end=" PTR_FORMAT " " SIZE_FORMAT,
 591                              split_type,
 592                              po_beg, addr_to_region_idx(po_beg),
 593                              po_end, addr_to_region_idx(po_end));
 594     }
 595   }
 596 
 597   return source_next;
 598 }
 599 
 600 bool ParallelCompactData::summarize(SplitInfo& split_info,
 601                                     HeapWord* source_beg, HeapWord* source_end,
 602                                     HeapWord** source_next,
 603                                     HeapWord* target_beg, HeapWord* target_end,
 604                                     HeapWord** target_next)
 605 {
 606   if (TraceParallelOldGCSummaryPhase) {
 607     HeapWord* const source_next_val = source_next == NULL ? NULL : *source_next;
 608     tty->print_cr("sb=" PTR_FORMAT " se=" PTR_FORMAT " sn=" PTR_FORMAT
 609                   "tb=" PTR_FORMAT " te=" PTR_FORMAT " tn=" PTR_FORMAT,
 610                   source_beg, source_end, source_next_val,
 611                   target_beg, target_end, *target_next);
 612   }
 613 
 614   size_t cur_region = addr_to_region_idx(source_beg);
 615   const size_t end_region = addr_to_region_idx(region_align_up(source_end));
 616 
 617   HeapWord *dest_addr = target_beg;
 618   while (cur_region < end_region) {
 619     // The destination must be set even if the region has no data.
 620     _region_data[cur_region].set_destination(dest_addr);
 621 
 622     size_t words = _region_data[cur_region].data_size();
 623     if (words > 0) {
 624       // If cur_region does not fit entirely into the target space, find a point
 625       // at which the source space can be 'split' so that part is copied to the
 626       // target space and the rest is copied elsewhere.
 627       if (dest_addr + words > target_end) {
 628         assert(source_next != NULL, "source_next is NULL when splitting");
 629         *source_next = summarize_split_space(cur_region, split_info, dest_addr,
 630                                              target_end, target_next);
 631         return false;
 632       }
 633 
 634       // Compute the destination_count for cur_region, and if necessary, update
 635       // source_region for a destination region.  The source_region field is
 636       // updated if cur_region is the first (left-most) region to be copied to a
 637       // destination region.
 638       //
 639       // The destination_count calculation is a bit subtle.  A region that has
 640       // data that compacts into itself does not count itself as a destination.
 641       // This maintains the invariant that a zero count means the region is
 642       // available and can be claimed and then filled.
 643       uint destination_count = 0;
 644       if (split_info.is_split(cur_region)) {
 645         // The current region has been split:  the partial object will be copied
 646         // to one destination space and the remaining data will be copied to
 647         // another destination space.  Adjust the initial destination_count and,
 648         // if necessary, set the source_region field if the partial object will
 649         // cross a destination region boundary.
 650         destination_count = split_info.destination_count();
 651         if (destination_count == 2) {
 652           size_t dest_idx = addr_to_region_idx(split_info.dest_region_addr());
 653           _region_data[dest_idx].set_source_region(cur_region);
 654         }
 655       }
 656 
 657       HeapWord* const last_addr = dest_addr + words - 1;
 658       const size_t dest_region_1 = addr_to_region_idx(dest_addr);
 659       const size_t dest_region_2 = addr_to_region_idx(last_addr);
 660 
 661       // Initially assume that the destination regions will be the same and
 662       // adjust the value below if necessary.  Under this assumption, if
 663       // cur_region == dest_region_2, then cur_region will be compacted
 664       // completely into itself.
 665       destination_count += cur_region == dest_region_2 ? 0 : 1;
 666       if (dest_region_1 != dest_region_2) {
 667         // Destination regions differ; adjust destination_count.
 668         destination_count += 1;
 669         // Data from cur_region will be copied to the start of dest_region_2.
 670         _region_data[dest_region_2].set_source_region(cur_region);
 671       } else if (region_offset(dest_addr) == 0) {
 672         // Data from cur_region will be copied to the start of the destination
 673         // region.
 674         _region_data[dest_region_1].set_source_region(cur_region);
 675       }
 676 
 677       _region_data[cur_region].set_destination_count(destination_count);
 678       _region_data[cur_region].set_data_location(region_to_addr(cur_region));
 679       dest_addr += words;
 680     }
 681 
 682     ++cur_region;
 683   }
 684 
 685   *target_next = dest_addr;
 686   return true;
 687 }
 688 
 689 HeapWord* ParallelCompactData::calc_new_pointer(HeapWord* addr) {
 690   assert(addr != NULL, "Should detect NULL oop earlier");
 691   assert(PSParallelCompact::gc_heap()->is_in(addr), "addr not in heap");
 692 #ifdef ASSERT
 693   if (PSParallelCompact::mark_bitmap()->is_unmarked(addr)) {
 694     gclog_or_tty->print_cr("calc_new_pointer:: addr " PTR_FORMAT, addr);
 695   }
 696 #endif
 697   assert(PSParallelCompact::mark_bitmap()->is_marked(addr), "obj not marked");
 698 
 699   // Region covering the object.
 700   size_t region_index = addr_to_region_idx(addr);
 701   const RegionData* const region_ptr = region(region_index);
 702   HeapWord* const region_addr = region_align_down(addr);
 703 
 704   assert(addr < region_addr + RegionSize, "Region does not cover object");
 705   assert(addr_to_region_ptr(region_addr) == region_ptr, "sanity check");
 706 
 707   HeapWord* result = region_ptr->destination();
 708 
 709   // If all the data in the region is live, then the new location of the object
 710   // can be calculated from the destination of the region plus the offset of the
 711   // object in the region.
 712   if (region_ptr->data_size() == RegionSize) {
 713     result += pointer_delta(addr, region_addr);
 714     return result;
 715   }
 716 
 717   // The new location of the object is
 718   //    region destination +
 719   //    size of the partial object extending onto the region +
 720   //    sizes of the live objects in the Region that are to the left of addr
 721   const size_t partial_obj_size = region_ptr->partial_obj_size();
 722   HeapWord* const search_start = region_addr + partial_obj_size;
 723 
 724   const ParMarkBitMap* bitmap = PSParallelCompact::mark_bitmap();
 725   size_t live_to_left = bitmap->live_words_in_range(search_start, oop(addr));
 726 
 727   result += partial_obj_size + live_to_left;
 728   DEBUG_ONLY(PSParallelCompact::check_new_location(addr, result);)
 729   return result;
 730 }
 731 
 732 klassOop ParallelCompactData::calc_new_klass(klassOop old_klass) {
 733   klassOop updated_klass;
 734   if (PSParallelCompact::should_update_klass(old_klass)) {
 735     updated_klass = (klassOop) calc_new_pointer(old_klass);
 736   } else {
 737     updated_klass = old_klass;
 738   }
 739 
 740   return updated_klass;
 741 }
 742 
 743 #ifdef  ASSERT
 744 void ParallelCompactData::verify_clear(const PSVirtualSpace* vspace)
 745 {
 746   const size_t* const beg = (const size_t*)vspace->committed_low_addr();
 747   const size_t* const end = (const size_t*)vspace->committed_high_addr();
 748   for (const size_t* p = beg; p < end; ++p) {
 749     assert(*p == 0, "not zero");
 750   }
 751 }
 752 
 753 void ParallelCompactData::verify_clear()
 754 {
 755   verify_clear(_region_vspace);
 756 }
 757 #endif  // #ifdef ASSERT
 758 
 759 #ifdef NOT_PRODUCT
 760 ParallelCompactData::RegionData* debug_region(size_t region_index) {
 761   ParallelCompactData& sd = PSParallelCompact::summary_data();
 762   return sd.region(region_index);
 763 }
 764 #endif
 765 
 766 elapsedTimer        PSParallelCompact::_accumulated_time;
 767 unsigned int        PSParallelCompact::_total_invocations = 0;
 768 unsigned int        PSParallelCompact::_maximum_compaction_gc_num = 0;
 769 jlong               PSParallelCompact::_time_of_last_gc = 0;
 770 CollectorCounters*  PSParallelCompact::_counters = NULL;
 771 ParMarkBitMap       PSParallelCompact::_mark_bitmap;
 772 ParallelCompactData PSParallelCompact::_summary_data;
 773 
 774 PSParallelCompact::IsAliveClosure PSParallelCompact::_is_alive_closure;
 775 
 776 void PSParallelCompact::IsAliveClosure::do_object(oop p)   { ShouldNotReachHere(); }
 777 bool PSParallelCompact::IsAliveClosure::do_object_b(oop p) { return mark_bitmap()->is_marked(p); }
 778 
 779 void PSParallelCompact::KeepAliveClosure::do_oop(oop* p)       { PSParallelCompact::KeepAliveClosure::do_oop_work(p); }
 780 void PSParallelCompact::KeepAliveClosure::do_oop(narrowOop* p) { PSParallelCompact::KeepAliveClosure::do_oop_work(p); }
 781 
 782 PSParallelCompact::AdjustPointerClosure PSParallelCompact::_adjust_root_pointer_closure(true);
 783 PSParallelCompact::AdjustPointerClosure PSParallelCompact::_adjust_pointer_closure(false);
 784 
 785 void PSParallelCompact::AdjustPointerClosure::do_oop(oop* p)       { adjust_pointer(p, _is_root); }
 786 void PSParallelCompact::AdjustPointerClosure::do_oop(narrowOop* p) { adjust_pointer(p, _is_root); }
 787 
 788 void PSParallelCompact::FollowStackClosure::do_void() { follow_stack(_compaction_manager); }
 789 
 790 void PSParallelCompact::MarkAndPushClosure::do_oop(oop* p)       { mark_and_push(_compaction_manager, p); }
 791 void PSParallelCompact::MarkAndPushClosure::do_oop(narrowOop* p) { mark_and_push(_compaction_manager, p); }
 792 
 793 void PSParallelCompact::post_initialize() {
 794   ParallelScavengeHeap* heap = gc_heap();
 795   assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
 796 
 797   MemRegion mr = heap->reserved_region();
 798   _ref_processor = ReferenceProcessor::create_ref_processor(
 799     mr,                         // span
 800     true,                       // atomic_discovery
 801     true,                       // mt_discovery
 802     &_is_alive_closure,
 803     ParallelGCThreads,
 804     ParallelRefProcEnabled);
 805   _counters = new CollectorCounters("PSParallelCompact", 1);
 806 
 807   // Initialize static fields in ParCompactionManager.
 808   ParCompactionManager::initialize(mark_bitmap());
 809 }
 810 
 811 bool PSParallelCompact::initialize() {
 812   ParallelScavengeHeap* heap = gc_heap();
 813   assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
 814   MemRegion mr = heap->reserved_region();
 815 
 816   // Was the old gen get allocated successfully?
 817   if (!heap->old_gen()->is_allocated()) {
 818     return false;
 819   }
 820 
 821   initialize_space_info();
 822   initialize_dead_wood_limiter();
 823 
 824   if (!_mark_bitmap.initialize(mr)) {
 825     vm_shutdown_during_initialization("Unable to allocate bit map for "
 826       "parallel garbage collection for the requested heap size.");
 827     return false;
 828   }
 829 
 830   if (!_summary_data.initialize(mr)) {
 831     vm_shutdown_during_initialization("Unable to allocate tables for "
 832       "parallel garbage collection for the requested heap size.");
 833     return false;
 834   }
 835 
 836   return true;
 837 }
 838 
 839 void PSParallelCompact::initialize_space_info()
 840 {
 841   memset(&_space_info, 0, sizeof(_space_info));
 842 
 843   ParallelScavengeHeap* heap = gc_heap();
 844   PSYoungGen* young_gen = heap->young_gen();
 845   MutableSpace* perm_space = heap->perm_gen()->object_space();
 846 
 847   _space_info[perm_space_id].set_space(perm_space);
 848   _space_info[old_space_id].set_space(heap->old_gen()->object_space());
 849   _space_info[eden_space_id].set_space(young_gen->eden_space());
 850   _space_info[from_space_id].set_space(young_gen->from_space());
 851   _space_info[to_space_id].set_space(young_gen->to_space());
 852 
 853   _space_info[perm_space_id].set_start_array(heap->perm_gen()->start_array());
 854   _space_info[old_space_id].set_start_array(heap->old_gen()->start_array());
 855 
 856   _space_info[perm_space_id].set_min_dense_prefix(perm_space->top());
 857   if (TraceParallelOldGCDensePrefix) {
 858     tty->print_cr("perm min_dense_prefix=" PTR_FORMAT,
 859                   _space_info[perm_space_id].min_dense_prefix());
 860   }
 861 }
 862 
 863 void PSParallelCompact::initialize_dead_wood_limiter()
 864 {
 865   const size_t max = 100;
 866   _dwl_mean = double(MIN2(ParallelOldDeadWoodLimiterMean, max)) / 100.0;
 867   _dwl_std_dev = double(MIN2(ParallelOldDeadWoodLimiterStdDev, max)) / 100.0;
 868   _dwl_first_term = 1.0 / (sqrt(2.0 * M_PI) * _dwl_std_dev);
 869   DEBUG_ONLY(_dwl_initialized = true;)
 870   _dwl_adjustment = normal_distribution(1.0);
 871 }
 872 
 873 // Simple class for storing info about the heap at the start of GC, to be used
 874 // after GC for comparison/printing.
 875 class PreGCValues {
 876 public:
 877   PreGCValues() { }
 878   PreGCValues(ParallelScavengeHeap* heap) { fill(heap); }
 879 
 880   void fill(ParallelScavengeHeap* heap) {
 881     _heap_used      = heap->used();
 882     _young_gen_used = heap->young_gen()->used_in_bytes();
 883     _old_gen_used   = heap->old_gen()->used_in_bytes();
 884     _perm_gen_used  = heap->perm_gen()->used_in_bytes();
 885   };
 886 
 887   size_t heap_used() const      { return _heap_used; }
 888   size_t young_gen_used() const { return _young_gen_used; }
 889   size_t old_gen_used() const   { return _old_gen_used; }
 890   size_t perm_gen_used() const  { return _perm_gen_used; }
 891 
 892 private:
 893   size_t _heap_used;
 894   size_t _young_gen_used;
 895   size_t _old_gen_used;
 896   size_t _perm_gen_used;
 897 };
 898 
 899 void
 900 PSParallelCompact::clear_data_covering_space(SpaceId id)
 901 {
 902   // At this point, top is the value before GC, new_top() is the value that will
 903   // be set at the end of GC.  The marking bitmap is cleared to top; nothing
 904   // should be marked above top.  The summary data is cleared to the larger of
 905   // top & new_top.
 906   MutableSpace* const space = _space_info[id].space();
 907   HeapWord* const bot = space->bottom();
 908   HeapWord* const top = space->top();
 909   HeapWord* const max_top = MAX2(top, _space_info[id].new_top());
 910 
 911   const idx_t beg_bit = _mark_bitmap.addr_to_bit(bot);
 912   const idx_t end_bit = BitMap::word_align_up(_mark_bitmap.addr_to_bit(top));
 913   _mark_bitmap.clear_range(beg_bit, end_bit);
 914 
 915   const size_t beg_region = _summary_data.addr_to_region_idx(bot);
 916   const size_t end_region =
 917     _summary_data.addr_to_region_idx(_summary_data.region_align_up(max_top));
 918   _summary_data.clear_range(beg_region, end_region);
 919 
 920   // Clear the data used to 'split' regions.
 921   SplitInfo& split_info = _space_info[id].split_info();
 922   if (split_info.is_valid()) {
 923     split_info.clear();
 924   }
 925   DEBUG_ONLY(split_info.verify_clear();)
 926 }
 927 
 928 void PSParallelCompact::pre_compact(PreGCValues* pre_gc_values)
 929 {
 930   // Update the from & to space pointers in space_info, since they are swapped
 931   // at each young gen gc.  Do the update unconditionally (even though a
 932   // promotion failure does not swap spaces) because an unknown number of minor
 933   // collections will have swapped the spaces an unknown number of times.
 934   TraceTime tm("pre compact", print_phases(), true, gclog_or_tty);
 935   ParallelScavengeHeap* heap = gc_heap();
 936   _space_info[from_space_id].set_space(heap->young_gen()->from_space());
 937   _space_info[to_space_id].set_space(heap->young_gen()->to_space());
 938 
 939   pre_gc_values->fill(heap);
 940 
 941   ParCompactionManager::reset();
 942   NOT_PRODUCT(_mark_bitmap.reset_counters());
 943   DEBUG_ONLY(add_obj_count = add_obj_size = 0;)
 944   DEBUG_ONLY(mark_bitmap_count = mark_bitmap_size = 0;)
 945 
 946   // Increment the invocation count
 947   heap->increment_total_collections(true);
 948 
 949   // We need to track unique mark sweep invocations as well.
 950   _total_invocations++;
 951 
 952   if (PrintHeapAtGC) {
 953     Universe::print_heap_before_gc();
 954   }
 955 
 956   // Fill in TLABs
 957   heap->accumulate_statistics_all_tlabs();
 958   heap->ensure_parsability(true);  // retire TLABs
 959 
 960   if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
 961     HandleMark hm;  // Discard invalid handles created during verification
 962     gclog_or_tty->print(" VerifyBeforeGC:");
 963     Universe::verify(true);
 964   }
 965 
 966   // Verify object start arrays
 967   if (VerifyObjectStartArray &&
 968       VerifyBeforeGC) {
 969     heap->old_gen()->verify_object_start_array();
 970     heap->perm_gen()->verify_object_start_array();
 971   }
 972 
 973   DEBUG_ONLY(mark_bitmap()->verify_clear();)
 974   DEBUG_ONLY(summary_data().verify_clear();)
 975 
 976   // Have worker threads release resources the next time they run a task.
 977   gc_task_manager()->release_all_resources();
 978 }
 979 
 980 void PSParallelCompact::post_compact()
 981 {
 982   TraceTime tm("post compact", print_phases(), true, gclog_or_tty);
 983 
 984   for (unsigned int id = perm_space_id; id < last_space_id; ++id) {
 985     // Clear the marking bitmap, summary data and split info.
 986     clear_data_covering_space(SpaceId(id));
 987     // Update top().  Must be done after clearing the bitmap and summary data.
 988     _space_info[id].publish_new_top();
 989   }
 990 
 991   MutableSpace* const eden_space = _space_info[eden_space_id].space();
 992   MutableSpace* const from_space = _space_info[from_space_id].space();
 993   MutableSpace* const to_space   = _space_info[to_space_id].space();
 994 
 995   ParallelScavengeHeap* heap = gc_heap();
 996   bool eden_empty = eden_space->is_empty();
 997   if (!eden_empty) {
 998     eden_empty = absorb_live_data_from_eden(heap->size_policy(),
 999                                             heap->young_gen(), heap->old_gen());
1000   }
1001 
1002   // Update heap occupancy information which is used as input to the soft ref
1003   // clearing policy at the next gc.
1004   Universe::update_heap_info_at_gc();
1005 
1006   bool young_gen_empty = eden_empty && from_space->is_empty() &&
1007     to_space->is_empty();
1008 
1009   BarrierSet* bs = heap->barrier_set();
1010   if (bs->is_a(BarrierSet::ModRef)) {
1011     ModRefBarrierSet* modBS = (ModRefBarrierSet*)bs;
1012     MemRegion old_mr = heap->old_gen()->reserved();
1013     MemRegion perm_mr = heap->perm_gen()->reserved();
1014     assert(perm_mr.end() <= old_mr.start(), "Generations out of order");
1015 
1016     if (young_gen_empty) {
1017       modBS->clear(MemRegion(perm_mr.start(), old_mr.end()));
1018     } else {
1019       modBS->invalidate(MemRegion(perm_mr.start(), old_mr.end()));
1020     }
1021   }
1022 
1023   Threads::gc_epilogue();
1024   CodeCache::gc_epilogue();
1025 
1026   COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
1027 
1028   ref_processor()->enqueue_discovered_references(NULL);
1029 
1030   if (ZapUnusedHeapArea) {
1031     heap->gen_mangle_unused_area();
1032   }
1033 
1034   // Update time of last GC
1035   reset_millis_since_last_gc();
1036 }
1037 
1038 HeapWord*
1039 PSParallelCompact::compute_dense_prefix_via_density(const SpaceId id,
1040                                                     bool maximum_compaction)
1041 {
1042   const size_t region_size = ParallelCompactData::RegionSize;
1043   const ParallelCompactData& sd = summary_data();
1044 
1045   const MutableSpace* const space = _space_info[id].space();
1046   HeapWord* const top_aligned_up = sd.region_align_up(space->top());
1047   const RegionData* const beg_cp = sd.addr_to_region_ptr(space->bottom());
1048   const RegionData* const end_cp = sd.addr_to_region_ptr(top_aligned_up);
1049 
1050   // Skip full regions at the beginning of the space--they are necessarily part
1051   // of the dense prefix.
1052   size_t full_count = 0;
1053   const RegionData* cp;
1054   for (cp = beg_cp; cp < end_cp && cp->data_size() == region_size; ++cp) {
1055     ++full_count;
1056   }
1057 
1058   assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");
1059   const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;
1060   const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval;
1061   if (maximum_compaction || cp == end_cp || interval_ended) {
1062     _maximum_compaction_gc_num = total_invocations();
1063     return sd.region_to_addr(cp);
1064   }
1065 
1066   HeapWord* const new_top = _space_info[id].new_top();
1067   const size_t space_live = pointer_delta(new_top, space->bottom());
1068   const size_t space_used = space->used_in_words();
1069   const size_t space_capacity = space->capacity_in_words();
1070 
1071   const double cur_density = double(space_live) / space_capacity;
1072   const double deadwood_density =
1073     (1.0 - cur_density) * (1.0 - cur_density) * cur_density * cur_density;
1074   const size_t deadwood_goal = size_t(space_capacity * deadwood_density);
1075 
1076   if (TraceParallelOldGCDensePrefix) {
1077     tty->print_cr("cur_dens=%5.3f dw_dens=%5.3f dw_goal=" SIZE_FORMAT,
1078                   cur_density, deadwood_density, deadwood_goal);
1079     tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " "
1080                   "space_cap=" SIZE_FORMAT,
1081                   space_live, space_used,
1082                   space_capacity);
1083   }
1084 
1085   // XXX - Use binary search?
1086   HeapWord* dense_prefix = sd.region_to_addr(cp);
1087   const RegionData* full_cp = cp;
1088   const RegionData* const top_cp = sd.addr_to_region_ptr(space->top() - 1);
1089   while (cp < end_cp) {
1090     HeapWord* region_destination = cp->destination();
1091     const size_t cur_deadwood = pointer_delta(dense_prefix, region_destination);
1092     if (TraceParallelOldGCDensePrefix && Verbose) {
1093       tty->print_cr("c#=" SIZE_FORMAT_W(4) " dst=" PTR_FORMAT " "
1094                     "dp=" SIZE_FORMAT_W(8) " " "cdw=" SIZE_FORMAT_W(8),
1095                     sd.region(cp), region_destination,
1096                     dense_prefix, cur_deadwood);
1097     }
1098 
1099     if (cur_deadwood >= deadwood_goal) {
1100       // Found the region that has the correct amount of deadwood to the left.
1101       // This typically occurs after crossing a fairly sparse set of regions, so
1102       // iterate backwards over those sparse regions, looking for the region
1103       // that has the lowest density of live objects 'to the right.'
1104       size_t space_to_left = sd.region(cp) * region_size;
1105       size_t live_to_left = space_to_left - cur_deadwood;
1106       size_t space_to_right = space_capacity - space_to_left;
1107       size_t live_to_right = space_live - live_to_left;
1108       double density_to_right = double(live_to_right) / space_to_right;
1109       while (cp > full_cp) {
1110         --cp;
1111         const size_t prev_region_live_to_right = live_to_right -
1112           cp->data_size();
1113         const size_t prev_region_space_to_right = space_to_right + region_size;
1114         double prev_region_density_to_right =
1115           double(prev_region_live_to_right) / prev_region_space_to_right;
1116         if (density_to_right <= prev_region_density_to_right) {
1117           return dense_prefix;
1118         }
1119         if (TraceParallelOldGCDensePrefix && Verbose) {
1120           tty->print_cr("backing up from c=" SIZE_FORMAT_W(4) " d2r=%10.8f "
1121                         "pc_d2r=%10.8f", sd.region(cp), density_to_right,
1122                         prev_region_density_to_right);
1123         }
1124         dense_prefix -= region_size;
1125         live_to_right = prev_region_live_to_right;
1126         space_to_right = prev_region_space_to_right;
1127         density_to_right = prev_region_density_to_right;
1128       }
1129       return dense_prefix;
1130     }
1131 
1132     dense_prefix += region_size;
1133     ++cp;
1134   }
1135 
1136   return dense_prefix;
1137 }
1138 
1139 #ifndef PRODUCT
1140 void PSParallelCompact::print_dense_prefix_stats(const char* const algorithm,
1141                                                  const SpaceId id,
1142                                                  const bool maximum_compaction,
1143                                                  HeapWord* const addr)
1144 {
1145   const size_t region_idx = summary_data().addr_to_region_idx(addr);
1146   RegionData* const cp = summary_data().region(region_idx);
1147   const MutableSpace* const space = _space_info[id].space();
1148   HeapWord* const new_top = _space_info[id].new_top();
1149 
1150   const size_t space_live = pointer_delta(new_top, space->bottom());
1151   const size_t dead_to_left = pointer_delta(addr, cp->destination());
1152   const size_t space_cap = space->capacity_in_words();
1153   const double dead_to_left_pct = double(dead_to_left) / space_cap;
1154   const size_t live_to_right = new_top - cp->destination();
1155   const size_t dead_to_right = space->top() - addr - live_to_right;
1156 
1157   tty->print_cr("%s=" PTR_FORMAT " dpc=" SIZE_FORMAT_W(5) " "
1158                 "spl=" SIZE_FORMAT " "
1159                 "d2l=" SIZE_FORMAT " d2l%%=%6.4f "
1160                 "d2r=" SIZE_FORMAT " l2r=" SIZE_FORMAT
1161                 " ratio=%10.8f",
1162                 algorithm, addr, region_idx,
1163                 space_live,
1164                 dead_to_left, dead_to_left_pct,
1165                 dead_to_right, live_to_right,
1166                 double(dead_to_right) / live_to_right);
1167 }
1168 #endif  // #ifndef PRODUCT
1169 
1170 // Return a fraction indicating how much of the generation can be treated as
1171 // "dead wood" (i.e., not reclaimed).  The function uses a normal distribution
1172 // based on the density of live objects in the generation to determine a limit,
1173 // which is then adjusted so the return value is min_percent when the density is
1174 // 1.
1175 //
1176 // The following table shows some return values for a different values of the
1177 // standard deviation (ParallelOldDeadWoodLimiterStdDev); the mean is 0.5 and
1178 // min_percent is 1.
1179 //
1180 //                          fraction allowed as dead wood
1181 //         -----------------------------------------------------------------
1182 // density std_dev=70 std_dev=75 std_dev=80 std_dev=85 std_dev=90 std_dev=95
1183 // ------- ---------- ---------- ---------- ---------- ---------- ----------
1184 // 0.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
1185 // 0.05000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
1186 // 0.10000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
1187 // 0.15000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
1188 // 0.20000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
1189 // 0.25000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
1190 // 0.30000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
1191 // 0.35000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
1192 // 0.40000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
1193 // 0.45000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
1194 // 0.50000 0.13832410 0.11599237 0.09847664 0.08456518 0.07338887 0.06431510
1195 // 0.55000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
1196 // 0.60000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
1197 // 0.65000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
1198 // 0.70000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
1199 // 0.75000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
1200 // 0.80000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
1201 // 0.85000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
1202 // 0.90000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
1203 // 0.95000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
1204 // 1.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
1205 
1206 double PSParallelCompact::dead_wood_limiter(double density, size_t min_percent)
1207 {
1208   assert(_dwl_initialized, "uninitialized");
1209 
1210   // The raw limit is the value of the normal distribution at x = density.
1211   const double raw_limit = normal_distribution(density);
1212 
1213   // Adjust the raw limit so it becomes the minimum when the density is 1.
1214   //
1215   // First subtract the adjustment value (which is simply the precomputed value
1216   // normal_distribution(1.0)); this yields a value of 0 when the density is 1.
1217   // Then add the minimum value, so the minimum is returned when the density is
1218   // 1.  Finally, prevent negative values, which occur when the mean is not 0.5.
1219   const double min = double(min_percent) / 100.0;
1220   const double limit = raw_limit - _dwl_adjustment + min;
1221   return MAX2(limit, 0.0);
1222 }
1223 
1224 ParallelCompactData::RegionData*
1225 PSParallelCompact::first_dead_space_region(const RegionData* beg,
1226                                            const RegionData* end)
1227 {
1228   const size_t region_size = ParallelCompactData::RegionSize;
1229   ParallelCompactData& sd = summary_data();
1230   size_t left = sd.region(beg);
1231   size_t right = end > beg ? sd.region(end) - 1 : left;
1232 
1233   // Binary search.
1234   while (left < right) {
1235     // Equivalent to (left + right) / 2, but does not overflow.
1236     const size_t middle = left + (right - left) / 2;
1237     RegionData* const middle_ptr = sd.region(middle);
1238     HeapWord* const dest = middle_ptr->destination();
1239     HeapWord* const addr = sd.region_to_addr(middle);
1240     assert(dest != NULL, "sanity");
1241     assert(dest <= addr, "must move left");
1242 
1243     if (middle > left && dest < addr) {
1244       right = middle - 1;
1245     } else if (middle < right && middle_ptr->data_size() == region_size) {
1246       left = middle + 1;
1247     } else {
1248       return middle_ptr;
1249     }
1250   }
1251   return sd.region(left);
1252 }
1253 
1254 ParallelCompactData::RegionData*
1255 PSParallelCompact::dead_wood_limit_region(const RegionData* beg,
1256                                           const RegionData* end,
1257                                           size_t dead_words)
1258 {
1259   ParallelCompactData& sd = summary_data();
1260   size_t left = sd.region(beg);
1261   size_t right = end > beg ? sd.region(end) - 1 : left;
1262 
1263   // Binary search.
1264   while (left < right) {
1265     // Equivalent to (left + right) / 2, but does not overflow.
1266     const size_t middle = left + (right - left) / 2;
1267     RegionData* const middle_ptr = sd.region(middle);
1268     HeapWord* const dest = middle_ptr->destination();
1269     HeapWord* const addr = sd.region_to_addr(middle);
1270     assert(dest != NULL, "sanity");
1271     assert(dest <= addr, "must move left");
1272 
1273     const size_t dead_to_left = pointer_delta(addr, dest);
1274     if (middle > left && dead_to_left > dead_words) {
1275       right = middle - 1;
1276     } else if (middle < right && dead_to_left < dead_words) {
1277       left = middle + 1;
1278     } else {
1279       return middle_ptr;
1280     }
1281   }
1282   return sd.region(left);
1283 }
1284 
1285 // The result is valid during the summary phase, after the initial summarization
1286 // of each space into itself, and before final summarization.
1287 inline double
1288 PSParallelCompact::reclaimed_ratio(const RegionData* const cp,
1289                                    HeapWord* const bottom,
1290                                    HeapWord* const top,
1291                                    HeapWord* const new_top)
1292 {
1293   ParallelCompactData& sd = summary_data();
1294 
1295   assert(cp != NULL, "sanity");
1296   assert(bottom != NULL, "sanity");
1297   assert(top != NULL, "sanity");
1298   assert(new_top != NULL, "sanity");
1299   assert(top >= new_top, "summary data problem?");
1300   assert(new_top > bottom, "space is empty; should not be here");
1301   assert(new_top >= cp->destination(), "sanity");
1302   assert(top >= sd.region_to_addr(cp), "sanity");
1303 
1304   HeapWord* const destination = cp->destination();
1305   const size_t dense_prefix_live  = pointer_delta(destination, bottom);
1306   const size_t compacted_region_live = pointer_delta(new_top, destination);
1307   const size_t compacted_region_used = pointer_delta(top,
1308                                                      sd.region_to_addr(cp));
1309   const size_t reclaimable = compacted_region_used - compacted_region_live;
1310 
1311   const double divisor = dense_prefix_live + 1.25 * compacted_region_live;
1312   return double(reclaimable) / divisor;
1313 }
1314 
1315 // Return the address of the end of the dense prefix, a.k.a. the start of the
1316 // compacted region.  The address is always on a region boundary.
1317 //
1318 // Completely full regions at the left are skipped, since no compaction can
1319 // occur in those regions.  Then the maximum amount of dead wood to allow is
1320 // computed, based on the density (amount live / capacity) of the generation;
1321 // the region with approximately that amount of dead space to the left is
1322 // identified as the limit region.  Regions between the last completely full
1323 // region and the limit region are scanned and the one that has the best
1324 // (maximum) reclaimed_ratio() is selected.
1325 HeapWord*
1326 PSParallelCompact::compute_dense_prefix(const SpaceId id,
1327                                         bool maximum_compaction)
1328 {
1329   if (ParallelOldGCSplitALot) {
1330     if (_space_info[id].dense_prefix() != _space_info[id].space()->bottom()) {
1331       // The value was chosen to provoke splitting a young gen space; use it.
1332       return _space_info[id].dense_prefix();
1333     }
1334   }
1335 
1336   const size_t region_size = ParallelCompactData::RegionSize;
1337   const ParallelCompactData& sd = summary_data();
1338 
1339   const MutableSpace* const space = _space_info[id].space();
1340   HeapWord* const top = space->top();
1341   HeapWord* const top_aligned_up = sd.region_align_up(top);
1342   HeapWord* const new_top = _space_info[id].new_top();
1343   HeapWord* const new_top_aligned_up = sd.region_align_up(new_top);
1344   HeapWord* const bottom = space->bottom();
1345   const RegionData* const beg_cp = sd.addr_to_region_ptr(bottom);
1346   const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
1347   const RegionData* const new_top_cp =
1348     sd.addr_to_region_ptr(new_top_aligned_up);
1349 
1350   // Skip full regions at the beginning of the space--they are necessarily part
1351   // of the dense prefix.
1352   const RegionData* const full_cp = first_dead_space_region(beg_cp, new_top_cp);
1353   assert(full_cp->destination() == sd.region_to_addr(full_cp) ||
1354          space->is_empty(), "no dead space allowed to the left");
1355   assert(full_cp->data_size() < region_size || full_cp == new_top_cp - 1,
1356          "region must have dead space");
1357 
1358   // The gc number is saved whenever a maximum compaction is done, and used to
1359   // determine when the maximum compaction interval has expired.  This avoids
1360   // successive max compactions for different reasons.
1361   assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");
1362   const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;
1363   const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval ||
1364     total_invocations() == HeapFirstMaximumCompactionCount;
1365   if (maximum_compaction || full_cp == top_cp || interval_ended) {
1366     _maximum_compaction_gc_num = total_invocations();
1367     return sd.region_to_addr(full_cp);
1368   }
1369 
1370   const size_t space_live = pointer_delta(new_top, bottom);
1371   const size_t space_used = space->used_in_words();
1372   const size_t space_capacity = space->capacity_in_words();
1373 
1374   const double density = double(space_live) / double(space_capacity);
1375   const size_t min_percent_free =
1376           id == perm_space_id ? PermMarkSweepDeadRatio : MarkSweepDeadRatio;
1377   const double limiter = dead_wood_limiter(density, min_percent_free);
1378   const size_t dead_wood_max = space_used - space_live;
1379   const size_t dead_wood_limit = MIN2(size_t(space_capacity * limiter),
1380                                       dead_wood_max);
1381 
1382   if (TraceParallelOldGCDensePrefix) {
1383     tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " "
1384                   "space_cap=" SIZE_FORMAT,
1385                   space_live, space_used,
1386                   space_capacity);
1387     tty->print_cr("dead_wood_limiter(%6.4f, %d)=%6.4f "
1388                   "dead_wood_max=" SIZE_FORMAT " dead_wood_limit=" SIZE_FORMAT,
1389                   density, min_percent_free, limiter,
1390                   dead_wood_max, dead_wood_limit);
1391   }
1392 
1393   // Locate the region with the desired amount of dead space to the left.
1394   const RegionData* const limit_cp =
1395     dead_wood_limit_region(full_cp, top_cp, dead_wood_limit);
1396 
1397   // Scan from the first region with dead space to the limit region and find the
1398   // one with the best (largest) reclaimed ratio.
1399   double best_ratio = 0.0;
1400   const RegionData* best_cp = full_cp;
1401   for (const RegionData* cp = full_cp; cp < limit_cp; ++cp) {
1402     double tmp_ratio = reclaimed_ratio(cp, bottom, top, new_top);
1403     if (tmp_ratio > best_ratio) {
1404       best_cp = cp;
1405       best_ratio = tmp_ratio;
1406     }
1407   }
1408 
1409 #if     0
1410   // Something to consider:  if the region with the best ratio is 'close to' the
1411   // first region w/free space, choose the first region with free space
1412   // ("first-free").  The first-free region is usually near the start of the
1413   // heap, which means we are copying most of the heap already, so copy a bit
1414   // more to get complete compaction.
1415   if (pointer_delta(best_cp, full_cp, sizeof(RegionData)) < 4) {
1416     _maximum_compaction_gc_num = total_invocations();
1417     best_cp = full_cp;
1418   }
1419 #endif  // #if 0
1420 
1421   return sd.region_to_addr(best_cp);
1422 }
1423 
1424 #ifndef PRODUCT
1425 void
1426 PSParallelCompact::fill_with_live_objects(SpaceId id, HeapWord* const start,
1427                                           size_t words)
1428 {
1429   if (TraceParallelOldGCSummaryPhase) {
1430     tty->print_cr("fill_with_live_objects [" PTR_FORMAT " " PTR_FORMAT ") "
1431                   SIZE_FORMAT, start, start + words, words);
1432   }
1433 
1434   ObjectStartArray* const start_array = _space_info[id].start_array();
1435   CollectedHeap::fill_with_objects(start, words);
1436   for (HeapWord* p = start; p < start + words; p += oop(p)->size()) {
1437     _mark_bitmap.mark_obj(p, words);
1438     _summary_data.add_obj(p, words);
1439     start_array->allocate_block(p);
1440   }
1441 }
1442 
1443 void
1444 PSParallelCompact::summarize_new_objects(SpaceId id, HeapWord* start)
1445 {
1446   ParallelCompactData& sd = summary_data();
1447   MutableSpace* space = _space_info[id].space();
1448 
1449   // Find the source and destination start addresses.
1450   HeapWord* const src_addr = sd.region_align_down(start);
1451   HeapWord* dst_addr;
1452   if (src_addr < start) {
1453     dst_addr = sd.addr_to_region_ptr(src_addr)->destination();
1454   } else if (src_addr > space->bottom()) {
1455     // The start (the original top() value) is aligned to a region boundary so
1456     // the associated region does not have a destination.  Compute the
1457     // destination from the previous region.
1458     RegionData* const cp = sd.addr_to_region_ptr(src_addr) - 1;
1459     dst_addr = cp->destination() + cp->data_size();
1460   } else {
1461     // Filling the entire space.
1462     dst_addr = space->bottom();
1463   }
1464   assert(dst_addr != NULL, "sanity");
1465 
1466   // Update the summary data.
1467   bool result = _summary_data.summarize(_space_info[id].split_info(),
1468                                         src_addr, space->top(), NULL,
1469                                         dst_addr, space->end(),
1470                                         _space_info[id].new_top_addr());
1471   assert(result, "should not fail:  bad filler object size");
1472 }
1473 
1474 void
1475 PSParallelCompact::provoke_split_fill_survivor(SpaceId id)
1476 {
1477   if (total_invocations() % (ParallelOldGCSplitInterval * 3) != 0) {
1478     return;
1479   }
1480 
1481   MutableSpace* const space = _space_info[id].space();
1482   if (space->is_empty()) {
1483     HeapWord* b = space->bottom();
1484     HeapWord* t = b + space->capacity_in_words() / 2;
1485     space->set_top(t);
1486     if (ZapUnusedHeapArea) {
1487       space->set_top_for_allocations();
1488     }
1489 
1490     size_t obj_len = 8;
1491     while (b + obj_len <= t) {
1492       CollectedHeap::fill_with_object(b, obj_len);
1493       mark_bitmap()->mark_obj(b, obj_len);
1494       summary_data().add_obj(b, obj_len);
1495       b += obj_len;
1496       obj_len = (obj_len & 0x18) + 8; // 8 16 24 32 8 16 24 32 ...
1497     }
1498     if (b < t) {
1499       // The loop didn't completely fill to t (top); adjust top downward.
1500       space->set_top(b);
1501       if (ZapUnusedHeapArea) {
1502         space->set_top_for_allocations();
1503       }
1504     }
1505 
1506     HeapWord** nta = _space_info[id].new_top_addr();
1507     bool result = summary_data().summarize(_space_info[id].split_info(),
1508                                            space->bottom(), space->top(), NULL,
1509                                            space->bottom(), space->end(), nta);
1510     assert(result, "space must fit into itself");
1511   }
1512 }
1513 
1514 void
1515 PSParallelCompact::provoke_split(bool & max_compaction)
1516 {
1517   if (total_invocations() % ParallelOldGCSplitInterval != 0) {
1518     return;
1519   }
1520 
1521   const size_t region_size = ParallelCompactData::RegionSize;
1522   ParallelCompactData& sd = summary_data();
1523 
1524   MutableSpace* const eden_space = _space_info[eden_space_id].space();
1525   MutableSpace* const from_space = _space_info[from_space_id].space();
1526   const size_t eden_live = pointer_delta(eden_space->top(),
1527                                          _space_info[eden_space_id].new_top());
1528   const size_t from_live = pointer_delta(from_space->top(),
1529                                          _space_info[from_space_id].new_top());
1530 
1531   const size_t min_fill_size = CollectedHeap::min_fill_size();
1532   const size_t eden_free = pointer_delta(eden_space->end(), eden_space->top());
1533   const size_t eden_fillable = eden_free >= min_fill_size ? eden_free : 0;
1534   const size_t from_free = pointer_delta(from_space->end(), from_space->top());
1535   const size_t from_fillable = from_free >= min_fill_size ? from_free : 0;
1536 
1537   // Choose the space to split; need at least 2 regions live (or fillable).
1538   SpaceId id;
1539   MutableSpace* space;
1540   size_t live_words;
1541   size_t fill_words;
1542   if (eden_live + eden_fillable >= region_size * 2) {
1543     id = eden_space_id;
1544     space = eden_space;
1545     live_words = eden_live;
1546     fill_words = eden_fillable;
1547   } else if (from_live + from_fillable >= region_size * 2) {
1548     id = from_space_id;
1549     space = from_space;
1550     live_words = from_live;
1551     fill_words = from_fillable;
1552   } else {
1553     return; // Give up.
1554   }
1555   assert(fill_words == 0 || fill_words >= min_fill_size, "sanity");
1556 
1557   if (live_words < region_size * 2) {
1558     // Fill from top() to end() w/live objects of mixed sizes.
1559     HeapWord* const fill_start = space->top();
1560     live_words += fill_words;
1561 
1562     space->set_top(fill_start + fill_words);
1563     if (ZapUnusedHeapArea) {
1564       space->set_top_for_allocations();
1565     }
1566 
1567     HeapWord* cur_addr = fill_start;
1568     while (fill_words > 0) {
1569       const size_t r = (size_t)os::random() % (region_size / 2) + min_fill_size;
1570       size_t cur_size = MIN2(align_object_size_(r), fill_words);
1571       if (fill_words - cur_size < min_fill_size) {
1572         cur_size = fill_words; // Avoid leaving a fragment too small to fill.
1573       }
1574 
1575       CollectedHeap::fill_with_object(cur_addr, cur_size);
1576       mark_bitmap()->mark_obj(cur_addr, cur_size);
1577       sd.add_obj(cur_addr, cur_size);
1578 
1579       cur_addr += cur_size;
1580       fill_words -= cur_size;
1581     }
1582 
1583     summarize_new_objects(id, fill_start);
1584   }
1585 
1586   max_compaction = false;
1587 
1588   // Manipulate the old gen so that it has room for about half of the live data
1589   // in the target young gen space (live_words / 2).
1590   id = old_space_id;
1591   space = _space_info[id].space();
1592   const size_t free_at_end = space->free_in_words();
1593   const size_t free_target = align_object_size(live_words / 2);
1594   const size_t dead = pointer_delta(space->top(), _space_info[id].new_top());
1595 
1596   if (free_at_end >= free_target + min_fill_size) {
1597     // Fill space above top() and set the dense prefix so everything survives.
1598     HeapWord* const fill_start = space->top();
1599     const size_t fill_size = free_at_end - free_target;
1600     space->set_top(space->top() + fill_size);
1601     if (ZapUnusedHeapArea) {
1602       space->set_top_for_allocations();
1603     }
1604     fill_with_live_objects(id, fill_start, fill_size);
1605     summarize_new_objects(id, fill_start);
1606     _space_info[id].set_dense_prefix(sd.region_align_down(space->top()));
1607   } else if (dead + free_at_end > free_target) {
1608     // Find a dense prefix that makes the right amount of space available.
1609     HeapWord* cur = sd.region_align_down(space->top());
1610     HeapWord* cur_destination = sd.addr_to_region_ptr(cur)->destination();
1611     size_t dead_to_right = pointer_delta(space->end(), cur_destination);
1612     while (dead_to_right < free_target) {
1613       cur -= region_size;
1614       cur_destination = sd.addr_to_region_ptr(cur)->destination();
1615       dead_to_right = pointer_delta(space->end(), cur_destination);
1616     }
1617     _space_info[id].set_dense_prefix(cur);
1618   }
1619 }
1620 #endif // #ifndef PRODUCT
1621 
1622 void PSParallelCompact::summarize_spaces_quick()
1623 {
1624   for (unsigned int i = 0; i < last_space_id; ++i) {
1625     const MutableSpace* space = _space_info[i].space();
1626     HeapWord** nta = _space_info[i].new_top_addr();
1627     bool result = _summary_data.summarize(_space_info[i].split_info(),
1628                                           space->bottom(), space->top(), NULL,
1629                                           space->bottom(), space->end(), nta);
1630     assert(result, "space must fit into itself");
1631     _space_info[i].set_dense_prefix(space->bottom());
1632   }
1633 
1634 #ifndef PRODUCT
1635   if (ParallelOldGCSplitALot) {
1636     provoke_split_fill_survivor(to_space_id);
1637   }
1638 #endif // #ifndef PRODUCT
1639 }
1640 
1641 void PSParallelCompact::fill_dense_prefix_end(SpaceId id)
1642 {
1643   HeapWord* const dense_prefix_end = dense_prefix(id);
1644   const RegionData* region = _summary_data.addr_to_region_ptr(dense_prefix_end);
1645   const idx_t dense_prefix_bit = _mark_bitmap.addr_to_bit(dense_prefix_end);
1646   if (dead_space_crosses_boundary(region, dense_prefix_bit)) {
1647     // Only enough dead space is filled so that any remaining dead space to the
1648     // left is larger than the minimum filler object.  (The remainder is filled
1649     // during the copy/update phase.)
1650     //
1651     // The size of the dead space to the right of the boundary is not a
1652     // concern, since compaction will be able to use whatever space is
1653     // available.
1654     //
1655     // Here '||' is the boundary, 'x' represents a don't care bit and a box
1656     // surrounds the space to be filled with an object.
1657     //
1658     // In the 32-bit VM, each bit represents two 32-bit words:
1659     //                              +---+
1660     // a) beg_bits:  ...  x   x   x | 0 | ||   0   x  x  ...
1661     //    end_bits:  ...  x   x   x | 0 | ||   0   x  x  ...
1662     //                              +---+
1663     //
1664     // In the 64-bit VM, each bit represents one 64-bit word:
1665     //                              +------------+
1666     // b) beg_bits:  ...  x   x   x | 0   ||   0 | x  x  ...
1667     //    end_bits:  ...  x   x   1 | 0   ||   0 | x  x  ...
1668     //                              +------------+
1669     //                          +-------+
1670     // c) beg_bits:  ...  x   x | 0   0 | ||   0   x  x  ...
1671     //    end_bits:  ...  x   1 | 0   0 | ||   0   x  x  ...
1672     //                          +-------+
1673     //                      +-----------+
1674     // d) beg_bits:  ...  x | 0   0   0 | ||   0   x  x  ...
1675     //    end_bits:  ...  1 | 0   0   0 | ||   0   x  x  ...
1676     //                      +-----------+
1677     //                          +-------+
1678     // e) beg_bits:  ...  0   0 | 0   0 | ||   0   x  x  ...
1679     //    end_bits:  ...  0   0 | 0   0 | ||   0   x  x  ...
1680     //                          +-------+
1681 
1682     // Initially assume case a, c or e will apply.
1683     size_t obj_len = (size_t)oopDesc::header_size();
1684     HeapWord* obj_beg = dense_prefix_end - obj_len;
1685 
1686 #ifdef  _LP64
1687     if (_mark_bitmap.is_obj_end(dense_prefix_bit - 2)) {
1688       // Case b above.
1689       obj_beg = dense_prefix_end - 1;
1690     } else if (!_mark_bitmap.is_obj_end(dense_prefix_bit - 3) &&
1691                _mark_bitmap.is_obj_end(dense_prefix_bit - 4)) {
1692       // Case d above.
1693       obj_beg = dense_prefix_end - 3;
1694       obj_len = 3;
1695     }
1696 #endif  // #ifdef _LP64
1697 
1698     CollectedHeap::fill_with_object(obj_beg, obj_len);
1699     _mark_bitmap.mark_obj(obj_beg, obj_len);
1700     _summary_data.add_obj(obj_beg, obj_len);
1701     assert(start_array(id) != NULL, "sanity");
1702     start_array(id)->allocate_block(obj_beg);
1703   }
1704 }
1705 
1706 void
1707 PSParallelCompact::clear_source_region(HeapWord* beg_addr, HeapWord* end_addr)
1708 {
1709   RegionData* const beg_ptr = _summary_data.addr_to_region_ptr(beg_addr);
1710   HeapWord* const end_aligned_up = _summary_data.region_align_up(end_addr);
1711   RegionData* const end_ptr = _summary_data.addr_to_region_ptr(end_aligned_up);
1712   for (RegionData* cur = beg_ptr; cur < end_ptr; ++cur) {
1713     cur->set_source_region(0);
1714   }
1715 }
1716 
1717 void
1718 PSParallelCompact::summarize_space(SpaceId id, bool maximum_compaction)
1719 {
1720   assert(id < last_space_id, "id out of range");
1721   assert(_space_info[id].dense_prefix() == _space_info[id].space()->bottom() ||
1722          ParallelOldGCSplitALot && id == old_space_id,
1723          "should have been reset in summarize_spaces_quick()");
1724 
1725   const MutableSpace* space = _space_info[id].space();
1726   if (_space_info[id].new_top() != space->bottom()) {
1727     HeapWord* dense_prefix_end = compute_dense_prefix(id, maximum_compaction);
1728     _space_info[id].set_dense_prefix(dense_prefix_end);
1729 
1730 #ifndef PRODUCT
1731     if (TraceParallelOldGCDensePrefix) {
1732       print_dense_prefix_stats("ratio", id, maximum_compaction,
1733                                dense_prefix_end);
1734       HeapWord* addr = compute_dense_prefix_via_density(id, maximum_compaction);
1735       print_dense_prefix_stats("density", id, maximum_compaction, addr);
1736     }
1737 #endif  // #ifndef PRODUCT
1738 
1739     // Recompute the summary data, taking into account the dense prefix.  If
1740     // every last byte will be reclaimed, then the existing summary data which
1741     // compacts everything can be left in place.
1742     if (!maximum_compaction && dense_prefix_end != space->bottom()) {
1743       // If dead space crosses the dense prefix boundary, it is (at least
1744       // partially) filled with a dummy object, marked live and added to the
1745       // summary data.  This simplifies the copy/update phase and must be done
1746       // before the final locations of objects are determined, to prevent
1747       // leaving a fragment of dead space that is too small to fill.
1748       fill_dense_prefix_end(id);
1749 
1750       // Compute the destination of each Region, and thus each object.
1751       _summary_data.summarize_dense_prefix(space->bottom(), dense_prefix_end);
1752       _summary_data.summarize(_space_info[id].split_info(),
1753                               dense_prefix_end, space->top(), NULL,
1754                               dense_prefix_end, space->end(),
1755                               _space_info[id].new_top_addr());
1756     }
1757   }
1758 
1759   if (TraceParallelOldGCSummaryPhase) {
1760     const size_t region_size = ParallelCompactData::RegionSize;
1761     HeapWord* const dense_prefix_end = _space_info[id].dense_prefix();
1762     const size_t dp_region = _summary_data.addr_to_region_idx(dense_prefix_end);
1763     const size_t dp_words = pointer_delta(dense_prefix_end, space->bottom());
1764     HeapWord* const new_top = _space_info[id].new_top();
1765     const HeapWord* nt_aligned_up = _summary_data.region_align_up(new_top);
1766     const size_t cr_words = pointer_delta(nt_aligned_up, dense_prefix_end);
1767     tty->print_cr("id=%d cap=" SIZE_FORMAT " dp=" PTR_FORMAT " "
1768                   "dp_region=" SIZE_FORMAT " " "dp_count=" SIZE_FORMAT " "
1769                   "cr_count=" SIZE_FORMAT " " "nt=" PTR_FORMAT,
1770                   id, space->capacity_in_words(), dense_prefix_end,
1771                   dp_region, dp_words / region_size,
1772                   cr_words / region_size, new_top);
1773   }
1774 }
1775 
1776 #ifndef PRODUCT
1777 void PSParallelCompact::summary_phase_msg(SpaceId dst_space_id,
1778                                           HeapWord* dst_beg, HeapWord* dst_end,
1779                                           SpaceId src_space_id,
1780                                           HeapWord* src_beg, HeapWord* src_end)
1781 {
1782   if (TraceParallelOldGCSummaryPhase) {
1783     tty->print_cr("summarizing %d [%s] into %d [%s]:  "
1784                   "src=" PTR_FORMAT "-" PTR_FORMAT " "
1785                   SIZE_FORMAT "-" SIZE_FORMAT " "
1786                   "dst=" PTR_FORMAT "-" PTR_FORMAT " "
1787                   SIZE_FORMAT "-" SIZE_FORMAT,
1788                   src_space_id, space_names[src_space_id],
1789                   dst_space_id, space_names[dst_space_id],
1790                   src_beg, src_end,
1791                   _summary_data.addr_to_region_idx(src_beg),
1792                   _summary_data.addr_to_region_idx(src_end),
1793                   dst_beg, dst_end,
1794                   _summary_data.addr_to_region_idx(dst_beg),
1795                   _summary_data.addr_to_region_idx(dst_end));
1796   }
1797 }
1798 #endif  // #ifndef PRODUCT
1799 
1800 void PSParallelCompact::summary_phase(ParCompactionManager* cm,
1801                                       bool maximum_compaction)
1802 {
1803   EventMark m("2 summarize");
1804   TraceTime tm("summary phase", print_phases(), true, gclog_or_tty);
1805   // trace("2");
1806 
1807 #ifdef  ASSERT
1808   if (TraceParallelOldGCMarkingPhase) {
1809     tty->print_cr("add_obj_count=" SIZE_FORMAT " "
1810                   "add_obj_bytes=" SIZE_FORMAT,
1811                   add_obj_count, add_obj_size * HeapWordSize);
1812     tty->print_cr("mark_bitmap_count=" SIZE_FORMAT " "
1813                   "mark_bitmap_bytes=" SIZE_FORMAT,
1814                   mark_bitmap_count, mark_bitmap_size * HeapWordSize);
1815   }
1816 #endif  // #ifdef ASSERT
1817 
1818   // Quick summarization of each space into itself, to see how much is live.
1819   summarize_spaces_quick();
1820 
1821   if (TraceParallelOldGCSummaryPhase) {
1822     tty->print_cr("summary_phase:  after summarizing each space to self");
1823     Universe::print();
1824     NOT_PRODUCT(print_region_ranges());
1825     if (Verbose) {
1826       NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info));
1827     }
1828   }
1829 
1830   // The amount of live data that will end up in old space (assuming it fits).
1831   size_t old_space_total_live = 0;
1832   assert(perm_space_id < old_space_id, "should not count perm data here");
1833   for (unsigned int id = old_space_id; id < last_space_id; ++id) {
1834     old_space_total_live += pointer_delta(_space_info[id].new_top(),
1835                                           _space_info[id].space()->bottom());
1836   }
1837 
1838   MutableSpace* const old_space = _space_info[old_space_id].space();
1839   const size_t old_capacity = old_space->capacity_in_words();
1840   if (old_space_total_live > old_capacity) {
1841     // XXX - should also try to expand
1842     maximum_compaction = true;
1843   }
1844 #ifndef PRODUCT
1845   if (ParallelOldGCSplitALot && old_space_total_live < old_capacity) {
1846     provoke_split(maximum_compaction);
1847   }
1848 #endif // #ifndef PRODUCT
1849 
1850   // Permanent and Old generations.
1851   summarize_space(perm_space_id, maximum_compaction);
1852   summarize_space(old_space_id, maximum_compaction);
1853 
1854   // Summarize the remaining spaces in the young gen.  The initial target space
1855   // is the old gen.  If a space does not fit entirely into the target, then the
1856   // remainder is compacted into the space itself and that space becomes the new
1857   // target.
1858   SpaceId dst_space_id = old_space_id;
1859   HeapWord* dst_space_end = old_space->end();
1860   HeapWord** new_top_addr = _space_info[dst_space_id].new_top_addr();
1861   for (unsigned int id = eden_space_id; id < last_space_id; ++id) {
1862     const MutableSpace* space = _space_info[id].space();
1863     const size_t live = pointer_delta(_space_info[id].new_top(),
1864                                       space->bottom());
1865     const size_t available = pointer_delta(dst_space_end, *new_top_addr);
1866 
1867     NOT_PRODUCT(summary_phase_msg(dst_space_id, *new_top_addr, dst_space_end,
1868                                   SpaceId(id), space->bottom(), space->top());)
1869     if (live > 0 && live <= available) {
1870       // All the live data will fit.
1871       bool done = _summary_data.summarize(_space_info[id].split_info(),
1872                                           space->bottom(), space->top(),
1873                                           NULL,
1874                                           *new_top_addr, dst_space_end,
1875                                           new_top_addr);
1876       assert(done, "space must fit into old gen");
1877 
1878       // Reset the new_top value for the space.
1879       _space_info[id].set_new_top(space->bottom());
1880     } else if (live > 0) {
1881       // Attempt to fit part of the source space into the target space.
1882       HeapWord* next_src_addr = NULL;
1883       bool done = _summary_data.summarize(_space_info[id].split_info(),
1884                                           space->bottom(), space->top(),
1885                                           &next_src_addr,
1886                                           *new_top_addr, dst_space_end,
1887                                           new_top_addr);
1888       assert(!done, "space should not fit into old gen");
1889       assert(next_src_addr != NULL, "sanity");
1890 
1891       // The source space becomes the new target, so the remainder is compacted
1892       // within the space itself.
1893       dst_space_id = SpaceId(id);
1894       dst_space_end = space->end();
1895       new_top_addr = _space_info[id].new_top_addr();
1896       NOT_PRODUCT(summary_phase_msg(dst_space_id,
1897                                     space->bottom(), dst_space_end,
1898                                     SpaceId(id), next_src_addr, space->top());)
1899       done = _summary_data.summarize(_space_info[id].split_info(),
1900                                      next_src_addr, space->top(),
1901                                      NULL,
1902                                      space->bottom(), dst_space_end,
1903                                      new_top_addr);
1904       assert(done, "space must fit when compacted into itself");
1905       assert(*new_top_addr <= space->top(), "usage should not grow");
1906     }
1907   }
1908 
1909   if (TraceParallelOldGCSummaryPhase) {
1910     tty->print_cr("summary_phase:  after final summarization");
1911     Universe::print();
1912     NOT_PRODUCT(print_region_ranges());
1913     if (Verbose) {
1914       NOT_PRODUCT(print_generic_summary_data(_summary_data, _space_info));
1915     }
1916   }
1917 }
1918 
1919 // This method should contain all heap-specific policy for invoking a full
1920 // collection.  invoke_no_policy() will only attempt to compact the heap; it
1921 // will do nothing further.  If we need to bail out for policy reasons, scavenge
1922 // before full gc, or any other specialized behavior, it needs to be added here.
1923 //
1924 // Note that this method should only be called from the vm_thread while at a
1925 // safepoint.
1926 void PSParallelCompact::invoke(bool maximum_heap_compaction) {
1927   assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
1928   assert(Thread::current() == (Thread*)VMThread::vm_thread(),
1929          "should be in vm thread");
1930   ParallelScavengeHeap* heap = gc_heap();
1931   GCCause::Cause gc_cause = heap->gc_cause();
1932   assert(!heap->is_gc_active(), "not reentrant");
1933 
1934   PSAdaptiveSizePolicy* policy = heap->size_policy();
1935 
1936   // Before each allocation/collection attempt, find out from the
1937   // policy object if GCs are, on the whole, taking too long. If so,
1938   // bail out without attempting a collection.  The exceptions are
1939   // for explicitly requested GC's.
1940   if (!policy->gc_time_limit_exceeded() ||
1941       GCCause::is_user_requested_gc(gc_cause) ||
1942       GCCause::is_serviceability_requested_gc(gc_cause)) {
1943     IsGCActiveMark mark;
1944 
1945     if (ScavengeBeforeFullGC) {
1946       PSScavenge::invoke_no_policy();
1947     }
1948 
1949     PSParallelCompact::invoke_no_policy(maximum_heap_compaction);
1950   }
1951 }
1952 
1953 bool ParallelCompactData::region_contains(size_t region_index, HeapWord* addr) {
1954   size_t addr_region_index = addr_to_region_idx(addr);
1955   return region_index == addr_region_index;
1956 }
1957 
1958 // This method contains no policy. You should probably
1959 // be calling invoke() instead.
1960 void PSParallelCompact::invoke_no_policy(bool maximum_heap_compaction) {
1961   assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
1962   assert(ref_processor() != NULL, "Sanity");
1963 
1964   if (GC_locker::check_active_before_gc()) {
1965     return;
1966   }
1967 
1968   TimeStamp marking_start;
1969   TimeStamp compaction_start;
1970   TimeStamp collection_exit;
1971 
1972   ParallelScavengeHeap* heap = gc_heap();
1973   GCCause::Cause gc_cause = heap->gc_cause();
1974   PSYoungGen* young_gen = heap->young_gen();
1975   PSOldGen* old_gen = heap->old_gen();
1976   PSPermGen* perm_gen = heap->perm_gen();
1977   PSAdaptiveSizePolicy* size_policy = heap->size_policy();
1978 
1979   if (ZapUnusedHeapArea) {
1980     // Save information needed to minimize mangling
1981     heap->record_gen_tops_before_GC();
1982   }
1983 
1984   heap->pre_full_gc_dump();
1985 
1986   _print_phases = PrintGCDetails && PrintParallelOldGCPhaseTimes;
1987 
1988   // Make sure data structures are sane, make the heap parsable, and do other
1989   // miscellaneous bookkeeping.
1990   PreGCValues pre_gc_values;
1991   pre_compact(&pre_gc_values);
1992 
1993   // Get the compaction manager reserved for the VM thread.
1994   ParCompactionManager* const vmthread_cm =
1995     ParCompactionManager::manager_array(gc_task_manager()->workers());
1996 
1997   // Place after pre_compact() where the number of invocations is incremented.
1998   AdaptiveSizePolicyOutput(size_policy, heap->total_collections());
1999 
2000   {
2001     ResourceMark rm;
2002     HandleMark hm;
2003 
2004     const bool is_system_gc = gc_cause == GCCause::_java_lang_system_gc;
2005 
2006     // This is useful for debugging but don't change the output the
2007     // the customer sees.
2008     const char* gc_cause_str = "Full GC";
2009     if (is_system_gc && PrintGCDetails) {
2010       gc_cause_str = "Full GC (System)";
2011     }
2012     gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
2013     TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
2014     TraceTime t1(gc_cause_str, PrintGC, !PrintGCDetails, gclog_or_tty);
2015     TraceCollectorStats tcs(counters());
2016     TraceMemoryManagerStats tms(true /* Full GC */);
2017 
2018     if (TraceGen1Time) accumulated_time()->start();
2019 
2020     // Let the size policy know we're starting
2021     size_policy->major_collection_begin();
2022 
2023     // When collecting the permanent generation methodOops may be moving,
2024     // so we either have to flush all bcp data or convert it into bci.
2025     CodeCache::gc_prologue();
2026     Threads::gc_prologue();
2027 
2028     NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
2029     COMPILER2_PRESENT(DerivedPointerTable::clear());
2030 
2031     ref_processor()->enable_discovery();
2032     ref_processor()->setup_policy(maximum_heap_compaction);
2033 
2034     bool marked_for_unloading = false;
2035 
2036     marking_start.update();
2037     marking_phase(vmthread_cm, maximum_heap_compaction);
2038 
2039 #ifndef PRODUCT
2040     if (TraceParallelOldGCMarkingPhase) {
2041       gclog_or_tty->print_cr("marking_phase: cas_tries %d  cas_retries %d "
2042         "cas_by_another %d",
2043         mark_bitmap()->cas_tries(), mark_bitmap()->cas_retries(),
2044         mark_bitmap()->cas_by_another());
2045     }
2046 #endif  // #ifndef PRODUCT
2047 
2048     bool max_on_system_gc = UseMaximumCompactionOnSystemGC && is_system_gc;
2049     summary_phase(vmthread_cm, maximum_heap_compaction || max_on_system_gc);
2050 
2051     COMPILER2_PRESENT(assert(DerivedPointerTable::is_active(), "Sanity"));
2052     COMPILER2_PRESENT(DerivedPointerTable::set_active(false));
2053 
2054     // adjust_roots() updates Universe::_intArrayKlassObj which is
2055     // needed by the compaction for filling holes in the dense prefix.
2056     adjust_roots();
2057 
2058     compaction_start.update();
2059     // Does the perm gen always have to be done serially because
2060     // klasses are used in the update of an object?
2061     compact_perm(vmthread_cm);
2062 
2063     if (UseParallelOldGCCompacting) {
2064       compact();
2065     } else {
2066       compact_serial(vmthread_cm);
2067     }
2068 
2069     // Reset the mark bitmap, summary data, and do other bookkeeping.  Must be
2070     // done before resizing.
2071     post_compact();
2072 
2073     // Let the size policy know we're done
2074     size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause);
2075 
2076     if (UseAdaptiveSizePolicy) {
2077       if (PrintAdaptiveSizePolicy) {
2078         gclog_or_tty->print("AdaptiveSizeStart: ");
2079         gclog_or_tty->stamp();
2080         gclog_or_tty->print_cr(" collection: %d ",
2081                        heap->total_collections());
2082         if (Verbose) {
2083           gclog_or_tty->print("old_gen_capacity: %d young_gen_capacity: %d"
2084             " perm_gen_capacity: %d ",
2085             old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes(),
2086             perm_gen->capacity_in_bytes());
2087         }
2088       }
2089 
2090       // Don't check if the size_policy is ready here.  Let
2091       // the size_policy check that internally.
2092       if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&
2093           ((gc_cause != GCCause::_java_lang_system_gc) ||
2094             UseAdaptiveSizePolicyWithSystemGC)) {
2095         // Calculate optimal free space amounts
2096         assert(young_gen->max_size() >
2097           young_gen->from_space()->capacity_in_bytes() +
2098           young_gen->to_space()->capacity_in_bytes(),
2099           "Sizes of space in young gen are out-of-bounds");
2100         size_t max_eden_size = young_gen->max_size() -
2101           young_gen->from_space()->capacity_in_bytes() -
2102           young_gen->to_space()->capacity_in_bytes();
2103         size_policy->compute_generation_free_space(
2104                               young_gen->used_in_bytes(),
2105                               young_gen->eden_space()->used_in_bytes(),
2106                               old_gen->used_in_bytes(),
2107                               perm_gen->used_in_bytes(),
2108                               young_gen->eden_space()->capacity_in_bytes(),
2109                               old_gen->max_gen_size(),
2110                               max_eden_size,
2111                               true /* full gc*/,
2112                               gc_cause);
2113 
2114         heap->resize_old_gen(
2115           size_policy->calculated_old_free_size_in_bytes());
2116 
2117         // Don't resize the young generation at an major collection.  A
2118         // desired young generation size may have been calculated but
2119         // resizing the young generation complicates the code because the
2120         // resizing of the old generation may have moved the boundary
2121         // between the young generation and the old generation.  Let the
2122         // young generation resizing happen at the minor collections.
2123       }
2124       if (PrintAdaptiveSizePolicy) {
2125         gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ",
2126                        heap->total_collections());
2127       }
2128     }
2129 
2130     if (UsePerfData) {
2131       PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters();
2132       counters->update_counters();
2133       counters->update_old_capacity(old_gen->capacity_in_bytes());
2134       counters->update_young_capacity(young_gen->capacity_in_bytes());
2135     }
2136 
2137     heap->resize_all_tlabs();
2138 
2139     // We collected the perm gen, so we'll resize it here.
2140     perm_gen->compute_new_size(pre_gc_values.perm_gen_used());
2141 
2142     if (TraceGen1Time) accumulated_time()->stop();
2143 
2144     if (PrintGC) {
2145       if (PrintGCDetails) {
2146         // No GC timestamp here.  This is after GC so it would be confusing.
2147         young_gen->print_used_change(pre_gc_values.young_gen_used());
2148         old_gen->print_used_change(pre_gc_values.old_gen_used());
2149         heap->print_heap_change(pre_gc_values.heap_used());
2150         // Print perm gen last (print_heap_change() excludes the perm gen).
2151         perm_gen->print_used_change(pre_gc_values.perm_gen_used());
2152       } else {
2153         heap->print_heap_change(pre_gc_values.heap_used());
2154       }
2155     }
2156 
2157     // Track memory usage and detect low memory
2158     MemoryService::track_memory_usage();
2159     heap->update_counters();
2160 
2161     if (PrintGCDetails) {
2162       if (size_policy->print_gc_time_limit_would_be_exceeded()) {
2163         if (size_policy->gc_time_limit_exceeded()) {
2164           gclog_or_tty->print_cr("      GC time is exceeding GCTimeLimit "
2165             "of %d%%", GCTimeLimit);
2166         } else {
2167           gclog_or_tty->print_cr("      GC time would exceed GCTimeLimit "
2168             "of %d%%", GCTimeLimit);
2169         }
2170       }
2171       size_policy->set_print_gc_time_limit_would_be_exceeded(false);
2172     }
2173   }
2174 
2175   if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
2176     HandleMark hm;  // Discard invalid handles created during verification
2177     gclog_or_tty->print(" VerifyAfterGC:");
2178     Universe::verify(false);
2179   }
2180 
2181   // Re-verify object start arrays
2182   if (VerifyObjectStartArray &&
2183       VerifyAfterGC) {
2184     old_gen->verify_object_start_array();
2185     perm_gen->verify_object_start_array();
2186   }
2187 
2188   if (ZapUnusedHeapArea) {
2189     old_gen->object_space()->check_mangled_unused_area_complete();
2190     perm_gen->object_space()->check_mangled_unused_area_complete();
2191   }
2192 
2193   NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
2194 
2195   collection_exit.update();
2196 
2197   if (PrintHeapAtGC) {
2198     Universe::print_heap_after_gc();
2199   }
2200   if (PrintGCTaskTimeStamps) {
2201     gclog_or_tty->print_cr("VM-Thread " INT64_FORMAT " " INT64_FORMAT " "
2202                            INT64_FORMAT,
2203                            marking_start.ticks(), compaction_start.ticks(),
2204                            collection_exit.ticks());
2205     gc_task_manager()->print_task_time_stamps();
2206   }
2207 
2208   heap->post_full_gc_dump();
2209 
2210 #ifdef TRACESPINNING
2211   ParallelTaskTerminator::print_termination_counts();
2212 #endif
2213 }
2214 
2215 bool PSParallelCompact::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
2216                                              PSYoungGen* young_gen,
2217                                              PSOldGen* old_gen) {
2218   MutableSpace* const eden_space = young_gen->eden_space();
2219   assert(!eden_space->is_empty(), "eden must be non-empty");
2220   assert(young_gen->virtual_space()->alignment() ==
2221          old_gen->virtual_space()->alignment(), "alignments do not match");
2222 
2223   if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) {
2224     return false;
2225   }
2226 
2227   // Both generations must be completely committed.
2228   if (young_gen->virtual_space()->uncommitted_size() != 0) {
2229     return false;
2230   }
2231   if (old_gen->virtual_space()->uncommitted_size() != 0) {
2232     return false;
2233   }
2234 
2235   // Figure out how much to take from eden.  Include the average amount promoted
2236   // in the total; otherwise the next young gen GC will simply bail out to a
2237   // full GC.
2238   const size_t alignment = old_gen->virtual_space()->alignment();
2239   const size_t eden_used = eden_space->used_in_bytes();
2240   const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average();
2241   const size_t absorb_size = align_size_up(eden_used + promoted, alignment);
2242   const size_t eden_capacity = eden_space->capacity_in_bytes();
2243 
2244   if (absorb_size >= eden_capacity) {
2245     return false; // Must leave some space in eden.
2246   }
2247 
2248   const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size;
2249   if (new_young_size < young_gen->min_gen_size()) {
2250     return false; // Respect young gen minimum size.
2251   }
2252 
2253   if (TraceAdaptiveGCBoundary && Verbose) {
2254     gclog_or_tty->print(" absorbing " SIZE_FORMAT "K:  "
2255                         "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K "
2256                         "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K "
2257                         "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ",
2258                         absorb_size / K,
2259                         eden_capacity / K, (eden_capacity - absorb_size) / K,
2260                         young_gen->from_space()->used_in_bytes() / K,
2261                         young_gen->to_space()->used_in_bytes() / K,
2262                         young_gen->capacity_in_bytes() / K, new_young_size / K);
2263   }
2264 
2265   // Fill the unused part of the old gen.
2266   MutableSpace* const old_space = old_gen->object_space();
2267   HeapWord* const unused_start = old_space->top();
2268   size_t const unused_words = pointer_delta(old_space->end(), unused_start);
2269 
2270   if (unused_words > 0) {
2271     if (unused_words < CollectedHeap::min_fill_size()) {
2272       return false;  // If the old gen cannot be filled, must give up.
2273     }
2274     CollectedHeap::fill_with_objects(unused_start, unused_words);
2275   }
2276 
2277   // Take the live data from eden and set both top and end in the old gen to
2278   // eden top.  (Need to set end because reset_after_change() mangles the region
2279   // from end to virtual_space->high() in debug builds).
2280   HeapWord* const new_top = eden_space->top();
2281   old_gen->virtual_space()->expand_into(young_gen->virtual_space(),
2282                                         absorb_size);
2283   young_gen->reset_after_change();
2284   old_space->set_top(new_top);
2285   old_space->set_end(new_top);
2286   old_gen->reset_after_change();
2287 
2288   // Update the object start array for the filler object and the data from eden.
2289   ObjectStartArray* const start_array = old_gen->start_array();
2290   for (HeapWord* p = unused_start; p < new_top; p += oop(p)->size()) {
2291     start_array->allocate_block(p);
2292   }
2293 
2294   // Could update the promoted average here, but it is not typically updated at
2295   // full GCs and the value to use is unclear.  Something like
2296   //
2297   // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc.
2298 
2299   size_policy->set_bytes_absorbed_from_eden(absorb_size);
2300   return true;
2301 }
2302 
2303 GCTaskManager* const PSParallelCompact::gc_task_manager() {
2304   assert(ParallelScavengeHeap::gc_task_manager() != NULL,
2305     "shouldn't return NULL");
2306   return ParallelScavengeHeap::gc_task_manager();
2307 }
2308 
2309 void PSParallelCompact::marking_phase(ParCompactionManager* cm,
2310                                       bool maximum_heap_compaction) {
2311   // Recursively traverse all live objects and mark them
2312   EventMark m("1 mark object");
2313   TraceTime tm("marking phase", print_phases(), true, gclog_or_tty);
2314 
2315   ParallelScavengeHeap* heap = gc_heap();
2316   uint parallel_gc_threads = heap->gc_task_manager()->workers();
2317   TaskQueueSetSuper* qset = ParCompactionManager::region_array();
2318   ParallelTaskTerminator terminator(parallel_gc_threads, qset);
2319 
2320   PSParallelCompact::MarkAndPushClosure mark_and_push_closure(cm);
2321   PSParallelCompact::FollowStackClosure follow_stack_closure(cm);
2322 
2323   {
2324     TraceTime tm_m("par mark", print_phases(), true, gclog_or_tty);
2325     ParallelScavengeHeap::ParStrongRootsScope psrs;
2326 
2327     GCTaskQueue* q = GCTaskQueue::create();
2328 
2329     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::universe));
2330     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jni_handles));
2331     // We scan the thread roots in parallel
2332     Threads::create_thread_roots_marking_tasks(q);
2333     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::object_synchronizer));
2334     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::flat_profiler));
2335     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::management));
2336     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::system_dictionary));
2337     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jvmti));
2338     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::vm_symbols));
2339     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::code_cache));
2340 
2341     if (parallel_gc_threads > 1) {
2342       for (uint j = 0; j < parallel_gc_threads; j++) {
2343         q->enqueue(new StealMarkingTask(&terminator));
2344       }
2345     }
2346 
2347     WaitForBarrierGCTask* fin = WaitForBarrierGCTask::create();
2348     q->enqueue(fin);
2349 
2350     gc_task_manager()->add_list(q);
2351 
2352     fin->wait_for();
2353 
2354     // We have to release the barrier tasks!
2355     WaitForBarrierGCTask::destroy(fin);
2356   }
2357 
2358   // Process reference objects found during marking
2359   {
2360     TraceTime tm_r("reference processing", print_phases(), true, gclog_or_tty);
2361     if (ref_processor()->processing_is_mt()) {
2362       RefProcTaskExecutor task_executor;
2363       ref_processor()->process_discovered_references(
2364         is_alive_closure(), &mark_and_push_closure, &follow_stack_closure,
2365         &task_executor);
2366     } else {
2367       ref_processor()->process_discovered_references(
2368         is_alive_closure(), &mark_and_push_closure, &follow_stack_closure, NULL);
2369     }
2370   }
2371 
2372   TraceTime tm_c("class unloading", print_phases(), true, gclog_or_tty);
2373   // Follow system dictionary roots and unload classes.
2374   bool purged_class = SystemDictionary::do_unloading(is_alive_closure());
2375 
2376   // Follow code cache roots.
2377   CodeCache::do_unloading(is_alive_closure(), &mark_and_push_closure,
2378                           purged_class);
2379   follow_stack(cm); // Flush marking stack.
2380 
2381   // Update subklass/sibling/implementor links of live klasses
2382   // revisit_klass_stack is used in follow_weak_klass_links().
2383   follow_weak_klass_links();
2384 
2385   // Revisit memoized MDO's and clear any unmarked weak refs
2386   follow_mdo_weak_refs();
2387 
2388   // Visit symbol and interned string tables and delete unmarked oops
2389   SymbolTable::unlink(is_alive_closure());
2390   StringTable::unlink(is_alive_closure());
2391 
2392   assert(cm->marking_stack()->size() == 0, "stack should be empty by now");
2393   assert(cm->overflow_stack()->is_empty(), "stack should be empty by now");
2394 }
2395 
2396 // This should be moved to the shared markSweep code!
2397 class PSAlwaysTrueClosure: public BoolObjectClosure {
2398 public:
2399   void do_object(oop p) { ShouldNotReachHere(); }
2400   bool do_object_b(oop p) { return true; }
2401 };
2402 static PSAlwaysTrueClosure always_true;
2403 
2404 void PSParallelCompact::adjust_roots() {
2405   // Adjust the pointers to reflect the new locations
2406   EventMark m("3 adjust roots");
2407   TraceTime tm("adjust roots", print_phases(), true, gclog_or_tty);
2408 
2409   // General strong roots.
2410   Universe::oops_do(adjust_root_pointer_closure());
2411   ReferenceProcessor::oops_do(adjust_root_pointer_closure());
2412   JNIHandles::oops_do(adjust_root_pointer_closure());   // Global (strong) JNI handles
2413   Threads::oops_do(adjust_root_pointer_closure(), NULL);
2414   ObjectSynchronizer::oops_do(adjust_root_pointer_closure());
2415   FlatProfiler::oops_do(adjust_root_pointer_closure());
2416   Management::oops_do(adjust_root_pointer_closure());
2417   JvmtiExport::oops_do(adjust_root_pointer_closure());
2418   // SO_AllClasses
2419   SystemDictionary::oops_do(adjust_root_pointer_closure());
2420   vmSymbols::oops_do(adjust_root_pointer_closure());
2421 
2422   // Now adjust pointers in remaining weak roots.  (All of which should
2423   // have been cleared if they pointed to non-surviving objects.)
2424   // Global (weak) JNI handles
2425   JNIHandles::weak_oops_do(&always_true, adjust_root_pointer_closure());
2426 
2427   CodeCache::oops_do(adjust_pointer_closure());
2428   SymbolTable::oops_do(adjust_root_pointer_closure());
2429   StringTable::oops_do(adjust_root_pointer_closure());
2430   ref_processor()->weak_oops_do(adjust_root_pointer_closure());
2431   // Roots were visited so references into the young gen in roots
2432   // may have been scanned.  Process them also.
2433   // Should the reference processor have a span that excludes
2434   // young gen objects?
2435   PSScavenge::reference_processor()->weak_oops_do(
2436                                               adjust_root_pointer_closure());
2437 }
2438 
2439 void PSParallelCompact::compact_perm(ParCompactionManager* cm) {
2440   EventMark m("4 compact perm");
2441   TraceTime tm("compact perm gen", print_phases(), true, gclog_or_tty);
2442   // trace("4");
2443 
2444   gc_heap()->perm_gen()->start_array()->reset();
2445   move_and_update(cm, perm_space_id);
2446 }
2447 
2448 void PSParallelCompact::enqueue_region_draining_tasks(GCTaskQueue* q,
2449                                                       uint parallel_gc_threads)
2450 {
2451   TraceTime tm("drain task setup", print_phases(), true, gclog_or_tty);
2452 
2453   const unsigned int task_count = MAX2(parallel_gc_threads, 1U);
2454   for (unsigned int j = 0; j < task_count; j++) {
2455     q->enqueue(new DrainStacksCompactionTask());
2456   }
2457 
2458   // Find all regions that are available (can be filled immediately) and
2459   // distribute them to the thread stacks.  The iteration is done in reverse
2460   // order (high to low) so the regions will be removed in ascending order.
2461 
2462   const ParallelCompactData& sd = PSParallelCompact::summary_data();
2463 
2464   size_t fillable_regions = 0;   // A count for diagnostic purposes.
2465   unsigned int which = 0;       // The worker thread number.
2466 
2467   for (unsigned int id = to_space_id; id > perm_space_id; --id) {
2468     SpaceInfo* const space_info = _space_info + id;
2469     MutableSpace* const space = space_info->space();
2470     HeapWord* const new_top = space_info->new_top();
2471 
2472     const size_t beg_region = sd.addr_to_region_idx(space_info->dense_prefix());
2473     const size_t end_region =
2474       sd.addr_to_region_idx(sd.region_align_up(new_top));
2475     assert(end_region > 0, "perm gen cannot be empty");
2476 
2477     for (size_t cur = end_region - 1; cur >= beg_region; --cur) {
2478       if (sd.region(cur)->claim_unsafe()) {
2479         ParCompactionManager* cm = ParCompactionManager::manager_array(which);
2480         cm->save_for_processing(cur);
2481 
2482         if (TraceParallelOldGCCompactionPhase && Verbose) {
2483           const size_t count_mod_8 = fillable_regions & 7;
2484           if (count_mod_8 == 0) gclog_or_tty->print("fillable: ");
2485           gclog_or_tty->print(" " SIZE_FORMAT_W(7), cur);
2486           if (count_mod_8 == 7) gclog_or_tty->cr();
2487         }
2488 
2489         NOT_PRODUCT(++fillable_regions;)
2490 
2491         // Assign regions to threads in round-robin fashion.
2492         if (++which == task_count) {
2493           which = 0;
2494         }
2495       }
2496     }
2497   }
2498 
2499   if (TraceParallelOldGCCompactionPhase) {
2500     if (Verbose && (fillable_regions & 7) != 0) gclog_or_tty->cr();
2501     gclog_or_tty->print_cr("%u initially fillable regions", fillable_regions);
2502   }
2503 }
2504 
2505 #define PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING 4
2506 
2507 void PSParallelCompact::enqueue_dense_prefix_tasks(GCTaskQueue* q,
2508                                                     uint parallel_gc_threads) {
2509   TraceTime tm("dense prefix task setup", print_phases(), true, gclog_or_tty);
2510 
2511   ParallelCompactData& sd = PSParallelCompact::summary_data();
2512 
2513   // Iterate over all the spaces adding tasks for updating
2514   // regions in the dense prefix.  Assume that 1 gc thread
2515   // will work on opening the gaps and the remaining gc threads
2516   // will work on the dense prefix.
2517   unsigned int space_id;
2518   for (space_id = old_space_id; space_id < last_space_id; ++ space_id) {
2519     HeapWord* const dense_prefix_end = _space_info[space_id].dense_prefix();
2520     const MutableSpace* const space = _space_info[space_id].space();
2521 
2522     if (dense_prefix_end == space->bottom()) {
2523       // There is no dense prefix for this space.
2524       continue;
2525     }
2526 
2527     // The dense prefix is before this region.
2528     size_t region_index_end_dense_prefix =
2529         sd.addr_to_region_idx(dense_prefix_end);
2530     RegionData* const dense_prefix_cp =
2531       sd.region(region_index_end_dense_prefix);
2532     assert(dense_prefix_end == space->end() ||
2533            dense_prefix_cp->available() ||
2534            dense_prefix_cp->claimed(),
2535            "The region after the dense prefix should always be ready to fill");
2536 
2537     size_t region_index_start = sd.addr_to_region_idx(space->bottom());
2538 
2539     // Is there dense prefix work?
2540     size_t total_dense_prefix_regions =
2541       region_index_end_dense_prefix - region_index_start;
2542     // How many regions of the dense prefix should be given to
2543     // each thread?
2544     if (total_dense_prefix_regions > 0) {
2545       uint tasks_for_dense_prefix = 1;
2546       if (UseParallelDensePrefixUpdate) {
2547         if (total_dense_prefix_regions <=
2548             (parallel_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING)) {
2549           // Don't over partition.  This assumes that
2550           // PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING is a small integer value
2551           // so there are not many regions to process.
2552           tasks_for_dense_prefix = parallel_gc_threads;
2553         } else {
2554           // Over partition
2555           tasks_for_dense_prefix = parallel_gc_threads *
2556             PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING;
2557         }
2558       }
2559       size_t regions_per_thread = total_dense_prefix_regions /
2560         tasks_for_dense_prefix;
2561       // Give each thread at least 1 region.
2562       if (regions_per_thread == 0) {
2563         regions_per_thread = 1;
2564       }
2565 
2566       for (uint k = 0; k < tasks_for_dense_prefix; k++) {
2567         if (region_index_start >= region_index_end_dense_prefix) {
2568           break;
2569         }
2570         // region_index_end is not processed
2571         size_t region_index_end = MIN2(region_index_start + regions_per_thread,
2572                                        region_index_end_dense_prefix);
2573         q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id),
2574                                              region_index_start,
2575                                              region_index_end));
2576         region_index_start = region_index_end;
2577       }
2578     }
2579     // This gets any part of the dense prefix that did not
2580     // fit evenly.
2581     if (region_index_start < region_index_end_dense_prefix) {
2582       q->enqueue(new UpdateDensePrefixTask(SpaceId(space_id),
2583                                            region_index_start,
2584                                            region_index_end_dense_prefix));
2585     }
2586   }
2587 }
2588 
2589 void PSParallelCompact::enqueue_region_stealing_tasks(
2590                                      GCTaskQueue* q,
2591                                      ParallelTaskTerminator* terminator_ptr,
2592                                      uint parallel_gc_threads) {
2593   TraceTime tm("steal task setup", print_phases(), true, gclog_or_tty);
2594 
2595   // Once a thread has drained it's stack, it should try to steal regions from
2596   // other threads.
2597   if (parallel_gc_threads > 1) {
2598     for (uint j = 0; j < parallel_gc_threads; j++) {
2599       q->enqueue(new StealRegionCompactionTask(terminator_ptr));
2600     }
2601   }
2602 }
2603 
2604 void PSParallelCompact::compact() {
2605   EventMark m("5 compact");
2606   // trace("5");
2607   TraceTime tm("compaction phase", print_phases(), true, gclog_or_tty);
2608 
2609   ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
2610   assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
2611   PSOldGen* old_gen = heap->old_gen();
2612   old_gen->start_array()->reset();
2613   uint parallel_gc_threads = heap->gc_task_manager()->workers();
2614   TaskQueueSetSuper* qset = ParCompactionManager::region_array();
2615   ParallelTaskTerminator terminator(parallel_gc_threads, qset);
2616 
2617   GCTaskQueue* q = GCTaskQueue::create();
2618   enqueue_region_draining_tasks(q, parallel_gc_threads);
2619   enqueue_dense_prefix_tasks(q, parallel_gc_threads);
2620   enqueue_region_stealing_tasks(q, &terminator, parallel_gc_threads);
2621 
2622   {
2623     TraceTime tm_pc("par compact", print_phases(), true, gclog_or_tty);
2624 
2625     WaitForBarrierGCTask* fin = WaitForBarrierGCTask::create();
2626     q->enqueue(fin);
2627 
2628     gc_task_manager()->add_list(q);
2629 
2630     fin->wait_for();
2631 
2632     // We have to release the barrier tasks!
2633     WaitForBarrierGCTask::destroy(fin);
2634 
2635 #ifdef  ASSERT
2636     // Verify that all regions have been processed before the deferred updates.
2637     // Note that perm_space_id is skipped; this type of verification is not
2638     // valid until the perm gen is compacted by regions.
2639     for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2640       verify_complete(SpaceId(id));
2641     }
2642 #endif
2643   }
2644 
2645   {
2646     // Update the deferred objects, if any.  Any compaction manager can be used.
2647     TraceTime tm_du("deferred updates", print_phases(), true, gclog_or_tty);
2648     ParCompactionManager* cm = ParCompactionManager::manager_array(0);
2649     for (unsigned int id = old_space_id; id < last_space_id; ++id) {
2650       update_deferred_objects(cm, SpaceId(id));
2651     }
2652   }
2653 }
2654 
2655 #ifdef  ASSERT
2656 void PSParallelCompact::verify_complete(SpaceId space_id) {
2657   // All Regions between space bottom() to new_top() should be marked as filled
2658   // and all Regions between new_top() and top() should be available (i.e.,
2659   // should have been emptied).
2660   ParallelCompactData& sd = summary_data();
2661   SpaceInfo si = _space_info[space_id];
2662   HeapWord* new_top_addr = sd.region_align_up(si.new_top());
2663   HeapWord* old_top_addr = sd.region_align_up(si.space()->top());
2664   const size_t beg_region = sd.addr_to_region_idx(si.space()->bottom());
2665   const size_t new_top_region = sd.addr_to_region_idx(new_top_addr);
2666   const size_t old_top_region = sd.addr_to_region_idx(old_top_addr);
2667 
2668   bool issued_a_warning = false;
2669 
2670   size_t cur_region;
2671   for (cur_region = beg_region; cur_region < new_top_region; ++cur_region) {
2672     const RegionData* const c = sd.region(cur_region);
2673     if (!c->completed()) {
2674       warning("region " SIZE_FORMAT " not filled:  "
2675               "destination_count=" SIZE_FORMAT,
2676               cur_region, c->destination_count());
2677       issued_a_warning = true;
2678     }
2679   }
2680 
2681   for (cur_region = new_top_region; cur_region < old_top_region; ++cur_region) {
2682     const RegionData* const c = sd.region(cur_region);
2683     if (!c->available()) {
2684       warning("region " SIZE_FORMAT " not empty:   "
2685               "destination_count=" SIZE_FORMAT,
2686               cur_region, c->destination_count());
2687       issued_a_warning = true;
2688     }
2689   }
2690 
2691   if (issued_a_warning) {
2692     print_region_ranges();
2693   }
2694 }
2695 #endif  // #ifdef ASSERT
2696 
2697 void PSParallelCompact::compact_serial(ParCompactionManager* cm) {
2698   EventMark m("5 compact serial");
2699   TraceTime tm("compact serial", print_phases(), true, gclog_or_tty);
2700 
2701   ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
2702   assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
2703 
2704   PSYoungGen* young_gen = heap->young_gen();
2705   PSOldGen* old_gen = heap->old_gen();
2706 
2707   old_gen->start_array()->reset();
2708   old_gen->move_and_update(cm);
2709   young_gen->move_and_update(cm);
2710 }
2711 
2712 
2713 void PSParallelCompact::follow_stack(ParCompactionManager* cm) {
2714   while(!cm->overflow_stack()->is_empty()) {
2715     oop obj = cm->overflow_stack()->pop();
2716     obj->follow_contents(cm);
2717   }
2718 
2719   oop obj;
2720   // obj is a reference!!!
2721   while (cm->marking_stack()->pop_local(obj)) {
2722     // It would be nice to assert about the type of objects we might
2723     // pop, but they can come from anywhere, unfortunately.
2724     obj->follow_contents(cm);
2725   }
2726 }
2727 
2728 void
2729 PSParallelCompact::follow_weak_klass_links() {
2730   // All klasses on the revisit stack are marked at this point.
2731   // Update and follow all subklass, sibling and implementor links.
2732   if (PrintRevisitStats) {
2733     gclog_or_tty->print_cr("#classes in system dictionary = %d", SystemDictionary::number_of_classes());
2734   }
2735   for (uint i = 0; i < ParallelGCThreads + 1; i++) {
2736     ParCompactionManager* cm = ParCompactionManager::manager_array(i);
2737     KeepAliveClosure keep_alive_closure(cm);
2738     int length = cm->revisit_klass_stack()->length();
2739     if (PrintRevisitStats) {
2740       gclog_or_tty->print_cr("Revisit klass stack[%d] length = %d", i, length);
2741     }
2742     for (int j = 0; j < length; j++) {
2743       cm->revisit_klass_stack()->at(j)->follow_weak_klass_links(
2744         is_alive_closure(),
2745         &keep_alive_closure);
2746     }
2747     // revisit_klass_stack is cleared in reset()
2748     follow_stack(cm);
2749   }
2750 }
2751 
2752 void
2753 PSParallelCompact::revisit_weak_klass_link(ParCompactionManager* cm, Klass* k) {
2754   cm->revisit_klass_stack()->push(k);
2755 }
2756 
2757 void PSParallelCompact::revisit_mdo(ParCompactionManager* cm, DataLayout* p) {
2758   cm->revisit_mdo_stack()->push(p);
2759 }
2760 
2761 void PSParallelCompact::follow_mdo_weak_refs() {
2762   // All strongly reachable oops have been marked at this point;
2763   // we can visit and clear any weak references from MDO's which
2764   // we memoized during the strong marking phase.
2765   if (PrintRevisitStats) {
2766     gclog_or_tty->print_cr("#classes in system dictionary = %d", SystemDictionary::number_of_classes());
2767   }
2768   for (uint i = 0; i < ParallelGCThreads + 1; i++) {
2769     ParCompactionManager* cm = ParCompactionManager::manager_array(i);
2770     GrowableArray<DataLayout*>* rms = cm->revisit_mdo_stack();
2771     int length = rms->length();
2772     if (PrintRevisitStats) {
2773       gclog_or_tty->print_cr("Revisit MDO stack[%d] length = %d", i, length);
2774     }
2775     for (int j = 0; j < length; j++) {
2776       rms->at(j)->follow_weak_refs(is_alive_closure());
2777     }
2778     // revisit_mdo_stack is cleared in reset()
2779     follow_stack(cm);
2780   }
2781 }
2782 
2783 
2784 #ifdef VALIDATE_MARK_SWEEP
2785 
2786 void PSParallelCompact::track_adjusted_pointer(void* p, bool isroot) {
2787   if (!ValidateMarkSweep)
2788     return;
2789 
2790   if (!isroot) {
2791     if (_pointer_tracking) {
2792       guarantee(_adjusted_pointers->contains(p), "should have seen this pointer");
2793       _adjusted_pointers->remove(p);
2794     }
2795   } else {
2796     ptrdiff_t index = _root_refs_stack->find(p);
2797     if (index != -1) {
2798       int l = _root_refs_stack->length();
2799       if (l > 0 && l - 1 != index) {
2800         void* last = _root_refs_stack->pop();
2801         assert(last != p, "should be different");
2802         _root_refs_stack->at_put(index, last);
2803       } else {
2804         _root_refs_stack->remove(p);
2805       }
2806     }
2807   }
2808 }
2809 
2810 
2811 void PSParallelCompact::check_adjust_pointer(void* p) {
2812   _adjusted_pointers->push(p);
2813 }
2814 
2815 
2816 class AdjusterTracker: public OopClosure {
2817  public:
2818   AdjusterTracker() {};
2819   void do_oop(oop* o)         { PSParallelCompact::check_adjust_pointer(o); }
2820   void do_oop(narrowOop* o)   { PSParallelCompact::check_adjust_pointer(o); }
2821 };
2822 
2823 
2824 void PSParallelCompact::track_interior_pointers(oop obj) {
2825   if (ValidateMarkSweep) {
2826     _adjusted_pointers->clear();
2827     _pointer_tracking = true;
2828 
2829     AdjusterTracker checker;
2830     obj->oop_iterate(&checker);
2831   }
2832 }
2833 
2834 
2835 void PSParallelCompact::check_interior_pointers() {
2836   if (ValidateMarkSweep) {
2837     _pointer_tracking = false;
2838     guarantee(_adjusted_pointers->length() == 0, "should have processed the same pointers");
2839   }
2840 }
2841 
2842 
2843 void PSParallelCompact::reset_live_oop_tracking(bool at_perm) {
2844   if (ValidateMarkSweep) {
2845     guarantee((size_t)_live_oops->length() == _live_oops_index, "should be at end of live oops");
2846     _live_oops_index = at_perm ? _live_oops_index_at_perm : 0;
2847   }
2848 }
2849 
2850 
2851 void PSParallelCompact::register_live_oop(oop p, size_t size) {
2852   if (ValidateMarkSweep) {
2853     _live_oops->push(p);
2854     _live_oops_size->push(size);
2855     _live_oops_index++;
2856   }
2857 }
2858 
2859 void PSParallelCompact::validate_live_oop(oop p, size_t size) {
2860   if (ValidateMarkSweep) {
2861     oop obj = _live_oops->at((int)_live_oops_index);
2862     guarantee(obj == p, "should be the same object");
2863     guarantee(_live_oops_size->at((int)_live_oops_index) == size, "should be the same size");
2864     _live_oops_index++;
2865   }
2866 }
2867 
2868 void PSParallelCompact::live_oop_moved_to(HeapWord* q, size_t size,
2869                                   HeapWord* compaction_top) {
2870   assert(oop(q)->forwardee() == NULL || oop(q)->forwardee() == oop(compaction_top),
2871          "should be moved to forwarded location");
2872   if (ValidateMarkSweep) {
2873     PSParallelCompact::validate_live_oop(oop(q), size);
2874     _live_oops_moved_to->push(oop(compaction_top));
2875   }
2876   if (RecordMarkSweepCompaction) {
2877     _cur_gc_live_oops->push(q);
2878     _cur_gc_live_oops_moved_to->push(compaction_top);
2879     _cur_gc_live_oops_size->push(size);
2880   }
2881 }
2882 
2883 
2884 void PSParallelCompact::compaction_complete() {
2885   if (RecordMarkSweepCompaction) {
2886     GrowableArray<HeapWord*>* _tmp_live_oops          = _cur_gc_live_oops;
2887     GrowableArray<HeapWord*>* _tmp_live_oops_moved_to = _cur_gc_live_oops_moved_to;
2888     GrowableArray<size_t>   * _tmp_live_oops_size     = _cur_gc_live_oops_size;
2889 
2890     _cur_gc_live_oops           = _last_gc_live_oops;
2891     _cur_gc_live_oops_moved_to  = _last_gc_live_oops_moved_to;
2892     _cur_gc_live_oops_size      = _last_gc_live_oops_size;
2893     _last_gc_live_oops          = _tmp_live_oops;
2894     _last_gc_live_oops_moved_to = _tmp_live_oops_moved_to;
2895     _last_gc_live_oops_size     = _tmp_live_oops_size;
2896   }
2897 }
2898 
2899 
2900 void PSParallelCompact::print_new_location_of_heap_address(HeapWord* q) {
2901   if (!RecordMarkSweepCompaction) {
2902     tty->print_cr("Requires RecordMarkSweepCompaction to be enabled");
2903     return;
2904   }
2905 
2906   if (_last_gc_live_oops == NULL) {
2907     tty->print_cr("No compaction information gathered yet");
2908     return;
2909   }
2910 
2911   for (int i = 0; i < _last_gc_live_oops->length(); i++) {
2912     HeapWord* old_oop = _last_gc_live_oops->at(i);
2913     size_t    sz      = _last_gc_live_oops_size->at(i);
2914     if (old_oop <= q && q < (old_oop + sz)) {
2915       HeapWord* new_oop = _last_gc_live_oops_moved_to->at(i);
2916       size_t offset = (q - old_oop);
2917       tty->print_cr("Address " PTR_FORMAT, q);
2918       tty->print_cr(" Was in oop " PTR_FORMAT ", size %d, at offset %d", old_oop, sz, offset);
2919       tty->print_cr(" Now in oop " PTR_FORMAT ", actual address " PTR_FORMAT, new_oop, new_oop + offset);
2920       return;
2921     }
2922   }
2923 
2924   tty->print_cr("Address " PTR_FORMAT " not found in live oop information from last GC", q);
2925 }
2926 #endif //VALIDATE_MARK_SWEEP
2927 
2928 // Update interior oops in the ranges of regions [beg_region, end_region).
2929 void
2930 PSParallelCompact::update_and_deadwood_in_dense_prefix(ParCompactionManager* cm,
2931                                                        SpaceId space_id,
2932                                                        size_t beg_region,
2933                                                        size_t end_region) {
2934   ParallelCompactData& sd = summary_data();
2935   ParMarkBitMap* const mbm = mark_bitmap();
2936 
2937   HeapWord* beg_addr = sd.region_to_addr(beg_region);
2938   HeapWord* const end_addr = sd.region_to_addr(end_region);
2939   assert(beg_region <= end_region, "bad region range");
2940   assert(end_addr <= dense_prefix(space_id), "not in the dense prefix");
2941 
2942 #ifdef  ASSERT
2943   // Claim the regions to avoid triggering an assert when they are marked as
2944   // filled.
2945   for (size_t claim_region = beg_region; claim_region < end_region; ++claim_region) {
2946     assert(sd.region(claim_region)->claim_unsafe(), "claim() failed");
2947   }
2948 #endif  // #ifdef ASSERT
2949 
2950   if (beg_addr != space(space_id)->bottom()) {
2951     // Find the first live object or block of dead space that *starts* in this
2952     // range of regions.  If a partial object crosses onto the region, skip it;
2953     // it will be marked for 'deferred update' when the object head is
2954     // processed.  If dead space crosses onto the region, it is also skipped; it
2955     // will be filled when the prior region is processed.  If neither of those
2956     // apply, the first word in the region is the start of a live object or dead
2957     // space.
2958     assert(beg_addr > space(space_id)->bottom(), "sanity");
2959     const RegionData* const cp = sd.region(beg_region);
2960     if (cp->partial_obj_size() != 0) {
2961       beg_addr = sd.partial_obj_end(beg_region);
2962     } else if (dead_space_crosses_boundary(cp, mbm->addr_to_bit(beg_addr))) {
2963       beg_addr = mbm->find_obj_beg(beg_addr, end_addr);
2964     }
2965   }
2966 
2967   if (beg_addr < end_addr) {
2968     // A live object or block of dead space starts in this range of Regions.
2969      HeapWord* const dense_prefix_end = dense_prefix(space_id);
2970 
2971     // Create closures and iterate.
2972     UpdateOnlyClosure update_closure(mbm, cm, space_id);
2973     FillClosure fill_closure(cm, space_id);
2974     ParMarkBitMap::IterationStatus status;
2975     status = mbm->iterate(&update_closure, &fill_closure, beg_addr, end_addr,
2976                           dense_prefix_end);
2977     if (status == ParMarkBitMap::incomplete) {
2978       update_closure.do_addr(update_closure.source());
2979     }
2980   }
2981 
2982   // Mark the regions as filled.
2983   RegionData* const beg_cp = sd.region(beg_region);
2984   RegionData* const end_cp = sd.region(end_region);
2985   for (RegionData* cp = beg_cp; cp < end_cp; ++cp) {
2986     cp->set_completed();
2987   }
2988 }
2989 
2990 // Return the SpaceId for the space containing addr.  If addr is not in the
2991 // heap, last_space_id is returned.  In debug mode it expects the address to be
2992 // in the heap and asserts such.
2993 PSParallelCompact::SpaceId PSParallelCompact::space_id(HeapWord* addr) {
2994   assert(Universe::heap()->is_in_reserved(addr), "addr not in the heap");
2995 
2996   for (unsigned int id = perm_space_id; id < last_space_id; ++id) {
2997     if (_space_info[id].space()->contains(addr)) {
2998       return SpaceId(id);
2999     }
3000   }
3001 
3002   assert(false, "no space contains the addr");
3003   return last_space_id;
3004 }
3005 
3006 void PSParallelCompact::update_deferred_objects(ParCompactionManager* cm,
3007                                                 SpaceId id) {
3008   assert(id < last_space_id, "bad space id");
3009 
3010   ParallelCompactData& sd = summary_data();
3011   const SpaceInfo* const space_info = _space_info + id;
3012   ObjectStartArray* const start_array = space_info->start_array();
3013 
3014   const MutableSpace* const space = space_info->space();
3015   assert(space_info->dense_prefix() >= space->bottom(), "dense_prefix not set");
3016   HeapWord* const beg_addr = space_info->dense_prefix();
3017   HeapWord* const end_addr = sd.region_align_up(space_info->new_top());
3018 
3019   const RegionData* const beg_region = sd.addr_to_region_ptr(beg_addr);
3020   const RegionData* const end_region = sd.addr_to_region_ptr(end_addr);
3021   const RegionData* cur_region;
3022   for (cur_region = beg_region; cur_region < end_region; ++cur_region) {
3023     HeapWord* const addr = cur_region->deferred_obj_addr();
3024     if (addr != NULL) {
3025       if (start_array != NULL) {
3026         start_array->allocate_block(addr);
3027       }
3028       oop(addr)->update_contents(cm);
3029       assert(oop(addr)->is_oop_or_null(), "should be an oop now");
3030     }
3031   }
3032 }
3033 
3034 // Skip over count live words starting from beg, and return the address of the
3035 // next live word.  Unless marked, the word corresponding to beg is assumed to
3036 // be dead.  Callers must either ensure beg does not correspond to the middle of
3037 // an object, or account for those live words in some other way.  Callers must
3038 // also ensure that there are enough live words in the range [beg, end) to skip.
3039 HeapWord*
3040 PSParallelCompact::skip_live_words(HeapWord* beg, HeapWord* end, size_t count)
3041 {
3042   assert(count > 0, "sanity");
3043 
3044   ParMarkBitMap* m = mark_bitmap();
3045   idx_t bits_to_skip = m->words_to_bits(count);
3046   idx_t cur_beg = m->addr_to_bit(beg);
3047   const idx_t search_end = BitMap::word_align_up(m->addr_to_bit(end));
3048 
3049   do {
3050     cur_beg = m->find_obj_beg(cur_beg, search_end);
3051     idx_t cur_end = m->find_obj_end(cur_beg, search_end);
3052     const size_t obj_bits = cur_end - cur_beg + 1;
3053     if (obj_bits > bits_to_skip) {
3054       return m->bit_to_addr(cur_beg + bits_to_skip);
3055     }
3056     bits_to_skip -= obj_bits;
3057     cur_beg = cur_end + 1;
3058   } while (bits_to_skip > 0);
3059 
3060   // Skipping the desired number of words landed just past the end of an object.
3061   // Find the start of the next object.
3062   cur_beg = m->find_obj_beg(cur_beg, search_end);
3063   assert(cur_beg < m->addr_to_bit(end), "not enough live words to skip");
3064   return m->bit_to_addr(cur_beg);
3065 }
3066 
3067 HeapWord* PSParallelCompact::first_src_addr(HeapWord* const dest_addr,
3068                                             SpaceId src_space_id,
3069                                             size_t src_region_idx)
3070 {
3071   assert(summary_data().is_region_aligned(dest_addr), "not aligned");
3072 
3073   const SplitInfo& split_info = _space_info[src_space_id].split_info();
3074   if (split_info.dest_region_addr() == dest_addr) {
3075     // The partial object ending at the split point contains the first word to
3076     // be copied to dest_addr.
3077     return split_info.first_src_addr();
3078   }
3079 
3080   const ParallelCompactData& sd = summary_data();
3081   ParMarkBitMap* const bitmap = mark_bitmap();
3082   const size_t RegionSize = ParallelCompactData::RegionSize;
3083 
3084   assert(sd.is_region_aligned(dest_addr), "not aligned");
3085   const RegionData* const src_region_ptr = sd.region(src_region_idx);
3086   const size_t partial_obj_size = src_region_ptr->partial_obj_size();
3087   HeapWord* const src_region_destination = src_region_ptr->destination();
3088 
3089   assert(dest_addr >= src_region_destination, "wrong src region");
3090   assert(src_region_ptr->data_size() > 0, "src region cannot be empty");
3091 
3092   HeapWord* const src_region_beg = sd.region_to_addr(src_region_idx);
3093   HeapWord* const src_region_end = src_region_beg + RegionSize;
3094 
3095   HeapWord* addr = src_region_beg;
3096   if (dest_addr == src_region_destination) {
3097     // Return the first live word in the source region.
3098     if (partial_obj_size == 0) {
3099       addr = bitmap->find_obj_beg(addr, src_region_end);
3100       assert(addr < src_region_end, "no objects start in src region");
3101     }
3102     return addr;
3103   }
3104 
3105   // Must skip some live data.
3106   size_t words_to_skip = dest_addr - src_region_destination;
3107   assert(src_region_ptr->data_size() > words_to_skip, "wrong src region");
3108 
3109   if (partial_obj_size >= words_to_skip) {
3110     // All the live words to skip are part of the partial object.
3111     addr += words_to_skip;
3112     if (partial_obj_size == words_to_skip) {
3113       // Find the first live word past the partial object.
3114       addr = bitmap->find_obj_beg(addr, src_region_end);
3115       assert(addr < src_region_end, "wrong src region");
3116     }
3117     return addr;
3118   }
3119 
3120   // Skip over the partial object (if any).
3121   if (partial_obj_size != 0) {
3122     words_to_skip -= partial_obj_size;
3123     addr += partial_obj_size;
3124   }
3125 
3126   // Skip over live words due to objects that start in the region.
3127   addr = skip_live_words(addr, src_region_end, words_to_skip);
3128   assert(addr < src_region_end, "wrong src region");
3129   return addr;
3130 }
3131 
3132 void PSParallelCompact::decrement_destination_counts(ParCompactionManager* cm,
3133                                                      SpaceId src_space_id,
3134                                                      size_t beg_region,
3135                                                      HeapWord* end_addr)
3136 {
3137   ParallelCompactData& sd = summary_data();
3138 
3139 #ifdef ASSERT
3140   MutableSpace* const src_space = _space_info[src_space_id].space();
3141   HeapWord* const beg_addr = sd.region_to_addr(beg_region);
3142   assert(src_space->contains(beg_addr) || beg_addr == src_space->end(),
3143          "src_space_id does not match beg_addr");
3144   assert(src_space->contains(end_addr) || end_addr == src_space->end(),
3145          "src_space_id does not match end_addr");
3146 #endif // #ifdef ASSERT
3147 
3148   RegionData* const beg = sd.region(beg_region);
3149   RegionData* const end = sd.addr_to_region_ptr(sd.region_align_up(end_addr));
3150 
3151   // Regions up to new_top() are enqueued if they become available.
3152   HeapWord* const new_top = _space_info[src_space_id].new_top();
3153   RegionData* const enqueue_end =
3154     sd.addr_to_region_ptr(sd.region_align_up(new_top));
3155 
3156   for (RegionData* cur = beg; cur < end; ++cur) {
3157     assert(cur->data_size() > 0, "region must have live data");
3158     cur->decrement_destination_count();
3159     if (cur < enqueue_end && cur->available() && cur->claim()) {
3160       cm->save_for_processing(sd.region(cur));
3161     }
3162   }
3163 }
3164 
3165 size_t PSParallelCompact::next_src_region(MoveAndUpdateClosure& closure,
3166                                           SpaceId& src_space_id,
3167                                           HeapWord*& src_space_top,
3168                                           HeapWord* end_addr)
3169 {
3170   typedef ParallelCompactData::RegionData RegionData;
3171 
3172   ParallelCompactData& sd = PSParallelCompact::summary_data();
3173   const size_t region_size = ParallelCompactData::RegionSize;
3174 
3175   size_t src_region_idx = 0;
3176 
3177   // Skip empty regions (if any) up to the top of the space.
3178   HeapWord* const src_aligned_up = sd.region_align_up(end_addr);
3179   RegionData* src_region_ptr = sd.addr_to_region_ptr(src_aligned_up);
3180   HeapWord* const top_aligned_up = sd.region_align_up(src_space_top);
3181   const RegionData* const top_region_ptr =
3182     sd.addr_to_region_ptr(top_aligned_up);
3183   while (src_region_ptr < top_region_ptr && src_region_ptr->data_size() == 0) {
3184     ++src_region_ptr;
3185   }
3186 
3187   if (src_region_ptr < top_region_ptr) {
3188     // The next source region is in the current space.  Update src_region_idx
3189     // and the source address to match src_region_ptr.
3190     src_region_idx = sd.region(src_region_ptr);
3191     HeapWord* const src_region_addr = sd.region_to_addr(src_region_idx);
3192     if (src_region_addr > closure.source()) {
3193       closure.set_source(src_region_addr);
3194     }
3195     return src_region_idx;
3196   }
3197 
3198   // Switch to a new source space and find the first non-empty region.
3199   unsigned int space_id = src_space_id + 1;
3200   assert(space_id < last_space_id, "not enough spaces");
3201 
3202   HeapWord* const destination = closure.destination();
3203 
3204   do {
3205     MutableSpace* space = _space_info[space_id].space();
3206     HeapWord* const bottom = space->bottom();
3207     const RegionData* const bottom_cp = sd.addr_to_region_ptr(bottom);
3208 
3209     // Iterate over the spaces that do not compact into themselves.
3210     if (bottom_cp->destination() != bottom) {
3211       HeapWord* const top_aligned_up = sd.region_align_up(space->top());
3212       const RegionData* const top_cp = sd.addr_to_region_ptr(top_aligned_up);
3213 
3214       for (const RegionData* src_cp = bottom_cp; src_cp < top_cp; ++src_cp) {
3215         if (src_cp->live_obj_size() > 0) {
3216           // Found it.
3217           assert(src_cp->destination() == destination,
3218                  "first live obj in the space must match the destination");
3219           assert(src_cp->partial_obj_size() == 0,
3220                  "a space cannot begin with a partial obj");
3221 
3222           src_space_id = SpaceId(space_id);
3223           src_space_top = space->top();
3224           const size_t src_region_idx = sd.region(src_cp);
3225           closure.set_source(sd.region_to_addr(src_region_idx));
3226           return src_region_idx;
3227         } else {
3228           assert(src_cp->data_size() == 0, "sanity");
3229         }
3230       }
3231     }
3232   } while (++space_id < last_space_id);
3233 
3234   assert(false, "no source region was found");
3235   return 0;
3236 }
3237 
3238 void PSParallelCompact::fill_region(ParCompactionManager* cm, size_t region_idx)
3239 {
3240   typedef ParMarkBitMap::IterationStatus IterationStatus;
3241   const size_t RegionSize = ParallelCompactData::RegionSize;
3242   ParMarkBitMap* const bitmap = mark_bitmap();
3243   ParallelCompactData& sd = summary_data();
3244   RegionData* const region_ptr = sd.region(region_idx);
3245 
3246   // Get the items needed to construct the closure.
3247   HeapWord* dest_addr = sd.region_to_addr(region_idx);
3248   SpaceId dest_space_id = space_id(dest_addr);
3249   ObjectStartArray* start_array = _space_info[dest_space_id].start_array();
3250   HeapWord* new_top = _space_info[dest_space_id].new_top();
3251   assert(dest_addr < new_top, "sanity");
3252   const size_t words = MIN2(pointer_delta(new_top, dest_addr), RegionSize);
3253 
3254   // Get the source region and related info.
3255   size_t src_region_idx = region_ptr->source_region();
3256   SpaceId src_space_id = space_id(sd.region_to_addr(src_region_idx));
3257   HeapWord* src_space_top = _space_info[src_space_id].space()->top();
3258 
3259   MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words);
3260   closure.set_source(first_src_addr(dest_addr, src_space_id, src_region_idx));
3261 
3262   // Adjust src_region_idx to prepare for decrementing destination counts (the
3263   // destination count is not decremented when a region is copied to itself).
3264   if (src_region_idx == region_idx) {
3265     src_region_idx += 1;
3266   }
3267 
3268   if (bitmap->is_unmarked(closure.source())) {
3269     // The first source word is in the middle of an object; copy the remainder
3270     // of the object or as much as will fit.  The fact that pointer updates were
3271     // deferred will be noted when the object header is processed.
3272     HeapWord* const old_src_addr = closure.source();
3273     closure.copy_partial_obj();
3274     if (closure.is_full()) {
3275       decrement_destination_counts(cm, src_space_id, src_region_idx,
3276                                    closure.source());
3277       region_ptr->set_deferred_obj_addr(NULL);
3278       region_ptr->set_completed();
3279       return;
3280     }
3281 
3282     HeapWord* const end_addr = sd.region_align_down(closure.source());
3283     if (sd.region_align_down(old_src_addr) != end_addr) {
3284       // The partial object was copied from more than one source region.
3285       decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
3286 
3287       // Move to the next source region, possibly switching spaces as well.  All
3288       // args except end_addr may be modified.
3289       src_region_idx = next_src_region(closure, src_space_id, src_space_top,
3290                                        end_addr);
3291     }
3292   }
3293 
3294   do {
3295     HeapWord* const cur_addr = closure.source();
3296     HeapWord* const end_addr = MIN2(sd.region_align_up(cur_addr + 1),
3297                                     src_space_top);
3298     IterationStatus status = bitmap->iterate(&closure, cur_addr, end_addr);
3299 
3300     if (status == ParMarkBitMap::incomplete) {
3301       // The last obj that starts in the source region does not end in the
3302       // region.
3303       assert(closure.source() < end_addr, "sanity")
3304       HeapWord* const obj_beg = closure.source();
3305       HeapWord* const range_end = MIN2(obj_beg + closure.words_remaining(),
3306                                        src_space_top);
3307       HeapWord* const obj_end = bitmap->find_obj_end(obj_beg, range_end);
3308       if (obj_end < range_end) {
3309         // The end was found; the entire object will fit.
3310         status = closure.do_addr(obj_beg, bitmap->obj_size(obj_beg, obj_end));
3311         assert(status != ParMarkBitMap::would_overflow, "sanity");
3312       } else {
3313         // The end was not found; the object will not fit.
3314         assert(range_end < src_space_top, "obj cannot cross space boundary");
3315         status = ParMarkBitMap::would_overflow;
3316       }
3317     }
3318 
3319     if (status == ParMarkBitMap::would_overflow) {
3320       // The last object did not fit.  Note that interior oop updates were
3321       // deferred, then copy enough of the object to fill the region.
3322       region_ptr->set_deferred_obj_addr(closure.destination());
3323       status = closure.copy_until_full(); // copies from closure.source()
3324 
3325       decrement_destination_counts(cm, src_space_id, src_region_idx,
3326                                    closure.source());
3327       region_ptr->set_completed();
3328       return;
3329     }
3330 
3331     if (status == ParMarkBitMap::full) {
3332       decrement_destination_counts(cm, src_space_id, src_region_idx,
3333                                    closure.source());
3334       region_ptr->set_deferred_obj_addr(NULL);
3335       region_ptr->set_completed();
3336       return;
3337     }
3338 
3339     decrement_destination_counts(cm, src_space_id, src_region_idx, end_addr);
3340 
3341     // Move to the next source region, possibly switching spaces as well.  All
3342     // args except end_addr may be modified.
3343     src_region_idx = next_src_region(closure, src_space_id, src_space_top,
3344                                      end_addr);
3345   } while (true);
3346 }
3347 
3348 void
3349 PSParallelCompact::move_and_update(ParCompactionManager* cm, SpaceId space_id) {
3350   const MutableSpace* sp = space(space_id);
3351   if (sp->is_empty()) {
3352     return;
3353   }
3354 
3355   ParallelCompactData& sd = PSParallelCompact::summary_data();
3356   ParMarkBitMap* const bitmap = mark_bitmap();
3357   HeapWord* const dp_addr = dense_prefix(space_id);
3358   HeapWord* beg_addr = sp->bottom();
3359   HeapWord* end_addr = sp->top();
3360 
3361 #ifdef ASSERT
3362   assert(beg_addr <= dp_addr && dp_addr <= end_addr, "bad dense prefix");
3363   if (cm->should_verify_only()) {
3364     VerifyUpdateClosure verify_update(cm, sp);
3365     bitmap->iterate(&verify_update, beg_addr, end_addr);
3366     return;
3367   }
3368 
3369   if (cm->should_reset_only()) {
3370     ResetObjectsClosure reset_objects(cm);
3371     bitmap->iterate(&reset_objects, beg_addr, end_addr);
3372     return;
3373   }
3374 #endif
3375 
3376   const size_t beg_region = sd.addr_to_region_idx(beg_addr);
3377   const size_t dp_region = sd.addr_to_region_idx(dp_addr);
3378   if (beg_region < dp_region) {
3379     update_and_deadwood_in_dense_prefix(cm, space_id, beg_region, dp_region);
3380   }
3381 
3382   // The destination of the first live object that starts in the region is one
3383   // past the end of the partial object entering the region (if any).
3384   HeapWord* const dest_addr = sd.partial_obj_end(dp_region);
3385   HeapWord* const new_top = _space_info[space_id].new_top();
3386   assert(new_top >= dest_addr, "bad new_top value");
3387   const size_t words = pointer_delta(new_top, dest_addr);
3388 
3389   if (words > 0) {
3390     ObjectStartArray* start_array = _space_info[space_id].start_array();
3391     MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words);
3392 
3393     ParMarkBitMap::IterationStatus status;
3394     status = bitmap->iterate(&closure, dest_addr, end_addr);
3395     assert(status == ParMarkBitMap::full, "iteration not complete");
3396     assert(bitmap->find_obj_beg(closure.source(), end_addr) == end_addr,
3397            "live objects skipped because closure is full");
3398   }
3399 }
3400 
3401 jlong PSParallelCompact::millis_since_last_gc() {
3402   jlong ret_val = os::javaTimeMillis() - _time_of_last_gc;
3403   // XXX See note in genCollectedHeap::millis_since_last_gc().
3404   if (ret_val < 0) {
3405     NOT_PRODUCT(warning("time warp: %d", ret_val);)
3406     return 0;
3407   }
3408   return ret_val;
3409 }
3410 
3411 void PSParallelCompact::reset_millis_since_last_gc() {
3412   _time_of_last_gc = os::javaTimeMillis();
3413 }
3414 
3415 ParMarkBitMap::IterationStatus MoveAndUpdateClosure::copy_until_full()
3416 {
3417   if (source() != destination()) {
3418     DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3419     Copy::aligned_conjoint_words(source(), destination(), words_remaining());
3420   }
3421   update_state(words_remaining());
3422   assert(is_full(), "sanity");
3423   return ParMarkBitMap::full;
3424 }
3425 
3426 void MoveAndUpdateClosure::copy_partial_obj()
3427 {
3428   size_t words = words_remaining();
3429 
3430   HeapWord* const range_end = MIN2(source() + words, bitmap()->region_end());
3431   HeapWord* const end_addr = bitmap()->find_obj_end(source(), range_end);
3432   if (end_addr < range_end) {
3433     words = bitmap()->obj_size(source(), end_addr);
3434   }
3435 
3436   // This test is necessary; if omitted, the pointer updates to a partial object
3437   // that crosses the dense prefix boundary could be overwritten.
3438   if (source() != destination()) {
3439     DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3440     Copy::aligned_conjoint_words(source(), destination(), words);
3441   }
3442   update_state(words);
3443 }
3444 
3445 ParMarkBitMapClosure::IterationStatus
3446 MoveAndUpdateClosure::do_addr(HeapWord* addr, size_t words) {
3447   assert(destination() != NULL, "sanity");
3448   assert(bitmap()->obj_size(addr) == words, "bad size");
3449 
3450   _source = addr;
3451   assert(PSParallelCompact::summary_data().calc_new_pointer(source()) ==
3452          destination(), "wrong destination");
3453 
3454   if (words > words_remaining()) {
3455     return ParMarkBitMap::would_overflow;
3456   }
3457 
3458   // The start_array must be updated even if the object is not moving.
3459   if (_start_array != NULL) {
3460     _start_array->allocate_block(destination());
3461   }
3462 
3463   if (destination() != source()) {
3464     DEBUG_ONLY(PSParallelCompact::check_new_location(source(), destination());)
3465     Copy::aligned_conjoint_words(source(), destination(), words);
3466   }
3467 
3468   oop moved_oop = (oop) destination();
3469   moved_oop->update_contents(compaction_manager());
3470   assert(moved_oop->is_oop_or_null(), "Object should be whole at this point");
3471 
3472   update_state(words);
3473   assert(destination() == (HeapWord*)moved_oop + moved_oop->size(), "sanity");
3474   return is_full() ? ParMarkBitMap::full : ParMarkBitMap::incomplete;
3475 }
3476 
3477 UpdateOnlyClosure::UpdateOnlyClosure(ParMarkBitMap* mbm,
3478                                      ParCompactionManager* cm,
3479                                      PSParallelCompact::SpaceId space_id) :
3480   ParMarkBitMapClosure(mbm, cm),
3481   _space_id(space_id),
3482   _start_array(PSParallelCompact::start_array(space_id))
3483 {
3484 }
3485 
3486 // Updates the references in the object to their new values.
3487 ParMarkBitMapClosure::IterationStatus
3488 UpdateOnlyClosure::do_addr(HeapWord* addr, size_t words) {
3489   do_addr(addr);
3490   return ParMarkBitMap::incomplete;
3491 }
3492 
3493 // Verify the new location using the forwarding pointer
3494 // from MarkSweep::mark_sweep_phase2().  Set the mark_word
3495 // to the initial value.
3496 ParMarkBitMapClosure::IterationStatus
3497 PSParallelCompact::VerifyUpdateClosure::do_addr(HeapWord* addr, size_t words) {
3498   // The second arg (words) is not used.
3499   oop obj = (oop) addr;
3500   HeapWord* forwarding_ptr = (HeapWord*) obj->mark()->decode_pointer();
3501   HeapWord* new_pointer = summary_data().calc_new_pointer(obj);
3502   if (forwarding_ptr == NULL) {
3503     // The object is dead or not moving.
3504     assert(bitmap()->is_unmarked(obj) || (new_pointer == (HeapWord*) obj),
3505            "Object liveness is wrong.");
3506     return ParMarkBitMap::incomplete;
3507   }
3508   assert(UseParallelOldGCDensePrefix ||
3509          (HeapMaximumCompactionInterval > 1) ||
3510          (MarkSweepAlwaysCompactCount > 1) ||
3511          (forwarding_ptr == new_pointer),
3512     "Calculation of new location is incorrect");
3513   return ParMarkBitMap::incomplete;
3514 }
3515 
3516 // Reset objects modified for debug checking.
3517 ParMarkBitMapClosure::IterationStatus
3518 PSParallelCompact::ResetObjectsClosure::do_addr(HeapWord* addr, size_t words) {
3519   // The second arg (words) is not used.
3520   oop obj = (oop) addr;
3521   obj->init_mark();
3522   return ParMarkBitMap::incomplete;
3523 }
3524 
3525 // Prepare for compaction.  This method is executed once
3526 // (i.e., by a single thread) before compaction.
3527 // Save the updated location of the intArrayKlassObj for
3528 // filling holes in the dense prefix.
3529 void PSParallelCompact::compact_prologue() {
3530   _updated_int_array_klass_obj = (klassOop)
3531     summary_data().calc_new_pointer(Universe::intArrayKlassObj());
3532 }
3533