jdk8-mips64-public/hotspot: src/share/vm/gc_implementation/parallelScavenge/psParallelCompact.cpp@1fdb98a17101 (annotated)

src/share/vm/gc_implementation/parallelScavenge/psParallelCompact.cpp@1fdb98a17101 (annotated)

src/share/vm/gc_implementation/parallelScavenge/psParallelCompact.cpp

Sat, 19 Jul 2008 17:38:22 -0400

author: coleenp
date: Sat, 19 Jul 2008 17:38:22 -0400
changeset 672: 1fdb98a17101
parent 670: 9c2ecc2ffb12
child 704: 850fdf70db2b
permissions: -rw-r--r--

6716785: implicit null checks not triggering with CompressedOops
Summary: allocate alignment-sized page(s) below java heap so that memory accesses at heap_base+1page give signal and cause an implicit null check
Reviewed-by: kvn, jmasa, phh, jcoomes

 /*
  * Copyright 2005-2008 Sun Microsystems, Inc.  All Rights Reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  * CA 95054 USA or visit www.sun.com if you need additional information or
  * have any questions.
  *
  */
 #include "incls/_precompiled.incl"
 #include "incls/_psParallelCompact.cpp.incl"
 #include <math.h>
 // All sizes are in HeapWords.
 const size_t ParallelCompactData::Log2ChunkSize  = 9; // 512 words
 const size_t ParallelCompactData::ChunkSize      = (size_t)1 << Log2ChunkSize;
 const size_t ParallelCompactData::ChunkSizeBytes = ChunkSize << LogHeapWordSize;
 const size_t ParallelCompactData::ChunkSizeOffsetMask = ChunkSize - 1;
 const size_t ParallelCompactData::ChunkAddrOffsetMask = ChunkSizeBytes - 1;
 const size_t ParallelCompactData::ChunkAddrMask  = ~ChunkAddrOffsetMask;
 // 32-bit:  128 words covers 4 bitmap words
 // 64-bit:  128 words covers 2 bitmap words
 const size_t ParallelCompactData::Log2BlockSize   = 7; // 128 words
 const size_t ParallelCompactData::BlockSize       = (size_t)1 << Log2BlockSize;
 const size_t ParallelCompactData::BlockOffsetMask = BlockSize - 1;
 const size_t ParallelCompactData::BlockMask       = ~BlockOffsetMask;
 const size_t ParallelCompactData::BlocksPerChunk = ChunkSize / BlockSize;
 const ParallelCompactData::ChunkData::chunk_sz_t
 ParallelCompactData::ChunkData::dc_shift = 27;
 const ParallelCompactData::ChunkData::chunk_sz_t
 ParallelCompactData::ChunkData::dc_mask = ~0U << dc_shift;
 const ParallelCompactData::ChunkData::chunk_sz_t
 ParallelCompactData::ChunkData::dc_one = 0x1U << dc_shift;
 const ParallelCompactData::ChunkData::chunk_sz_t
 ParallelCompactData::ChunkData::los_mask = ~dc_mask;
 const ParallelCompactData::ChunkData::chunk_sz_t
 ParallelCompactData::ChunkData::dc_claimed = 0x8U << dc_shift;
 const ParallelCompactData::ChunkData::chunk_sz_t
 ParallelCompactData::ChunkData::dc_completed = 0xcU << dc_shift;
 #ifdef ASSERT
 short   ParallelCompactData::BlockData::_cur_phase = 0;
 #endif
 SpaceInfo PSParallelCompact::_space_info[PSParallelCompact::last_space_id];
 bool      PSParallelCompact::_print_phases = false;
 ReferenceProcessor* PSParallelCompact::_ref_processor = NULL;
 klassOop            PSParallelCompact::_updated_int_array_klass_obj = NULL;
 double PSParallelCompact::_dwl_mean;
 double PSParallelCompact::_dwl_std_dev;
 double PSParallelCompact::_dwl_first_term;
 double PSParallelCompact::_dwl_adjustment;
 #ifdef  ASSERT
 bool   PSParallelCompact::_dwl_initialized = false;
 #endif  // #ifdef ASSERT
 #ifdef VALIDATE_MARK_SWEEP
 GrowableArray<void*>*   PSParallelCompact::_root_refs_stack = NULL;
 GrowableArray<oop> *    PSParallelCompact::_live_oops = NULL;
 GrowableArray<oop> *    PSParallelCompact::_live_oops_moved_to = NULL;
 GrowableArray<size_t>*  PSParallelCompact::_live_oops_size = NULL;
 size_t                  PSParallelCompact::_live_oops_index = 0;
 size_t                  PSParallelCompact::_live_oops_index_at_perm = 0;
 GrowableArray<void*>*   PSParallelCompact::_other_refs_stack = NULL;
 GrowableArray<void*>*   PSParallelCompact::_adjusted_pointers = NULL;
 bool                    PSParallelCompact::_pointer_tracking = false;
 bool                    PSParallelCompact::_root_tracking = true;
 GrowableArray<HeapWord*>* PSParallelCompact::_cur_gc_live_oops = NULL;
 GrowableArray<HeapWord*>* PSParallelCompact::_cur_gc_live_oops_moved_to = NULL;
 GrowableArray<size_t>   * PSParallelCompact::_cur_gc_live_oops_size = NULL;
 GrowableArray<HeapWord*>* PSParallelCompact::_last_gc_live_oops = NULL;
 GrowableArray<HeapWord*>* PSParallelCompact::_last_gc_live_oops_moved_to = NULL;
 GrowableArray<size_t>   * PSParallelCompact::_last_gc_live_oops_size = NULL;
 #endif
 // XXX beg - verification code; only works while we also mark in object headers
 static void
 verify_mark_bitmap(ParMarkBitMap& _mark_bitmap)
 {
   ParallelScavengeHeap* heap = PSParallelCompact::gc_heap();
   PSPermGen* perm_gen = heap->perm_gen();
   PSOldGen* old_gen = heap->old_gen();
   PSYoungGen* young_gen = heap->young_gen();
   MutableSpace* perm_space = perm_gen->object_space();
   MutableSpace* old_space = old_gen->object_space();
   MutableSpace* eden_space = young_gen->eden_space();
   MutableSpace* from_space = young_gen->from_space();
   MutableSpace* to_space = young_gen->to_space();
   // 'from_space' here is the survivor space at the lower address.
   if (to_space->bottom() < from_space->bottom()) {
     from_space = to_space;
     to_space = young_gen->from_space();
   }
   HeapWord* boundaries[12];
   unsigned int bidx = 0;
   const unsigned int bidx_max = sizeof(boundaries) / sizeof(boundaries[0]);
   boundaries[0] = perm_space->bottom();
   boundaries[1] = perm_space->top();
   boundaries[2] = old_space->bottom();
   boundaries[3] = old_space->top();
   boundaries[4] = eden_space->bottom();
   boundaries[5] = eden_space->top();
   boundaries[6] = from_space->bottom();
   boundaries[7] = from_space->top();
   boundaries[8] = to_space->bottom();
   boundaries[9] = to_space->top();
   boundaries[10] = to_space->end();
   boundaries[11] = to_space->end();
   BitMap::idx_t beg_bit = 0;
   BitMap::idx_t end_bit;
   BitMap::idx_t tmp_bit;
   const BitMap::idx_t last_bit = _mark_bitmap.size();
   do {
     HeapWord* addr = _mark_bitmap.bit_to_addr(beg_bit);
     if (_mark_bitmap.is_marked(beg_bit)) {
       oop obj = (oop)addr;
       assert(obj->is_gc_marked(), "obj header is not marked");
       end_bit = _mark_bitmap.find_obj_end(beg_bit, last_bit);
       const size_t size = _mark_bitmap.obj_size(beg_bit, end_bit);
       assert(size == (size_t)obj->size(), "end bit wrong?");
       beg_bit = _mark_bitmap.find_obj_beg(beg_bit + 1, last_bit);
       assert(beg_bit > end_bit, "bit set in middle of an obj");
     } else {
       if (addr >= boundaries[bidx] && addr < boundaries[bidx + 1]) {
         // a dead object in the current space.
         oop obj = (oop)addr;
         end_bit = _mark_bitmap.addr_to_bit(addr + obj->size());
         assert(!obj->is_gc_marked(), "obj marked in header, not in bitmap");
         tmp_bit = beg_bit + 1;
         beg_bit = _mark_bitmap.find_obj_beg(tmp_bit, end_bit);
         assert(beg_bit == end_bit, "beg bit set in unmarked obj");
         beg_bit = _mark_bitmap.find_obj_end(tmp_bit, end_bit);
         assert(beg_bit == end_bit, "end bit set in unmarked obj");
       } else if (addr < boundaries[bidx + 2]) {
         // addr is between top in the current space and bottom in the next.
         end_bit = beg_bit + pointer_delta(boundaries[bidx + 2], addr);
         tmp_bit = beg_bit;
         beg_bit = _mark_bitmap.find_obj_beg(tmp_bit, end_bit);
         assert(beg_bit == end_bit, "beg bit set above top");
         beg_bit = _mark_bitmap.find_obj_end(tmp_bit, end_bit);
         assert(beg_bit == end_bit, "end bit set above top");
         bidx += 2;
       } else if (bidx < bidx_max - 2) {
         bidx += 2; // ???
       } else {
         tmp_bit = beg_bit;
         beg_bit = _mark_bitmap.find_obj_beg(tmp_bit, last_bit);
         assert(beg_bit == last_bit, "beg bit set outside heap");
         beg_bit = _mark_bitmap.find_obj_end(tmp_bit, last_bit);
         assert(beg_bit == last_bit, "end bit set outside heap");
       }
     }
   } while (beg_bit < last_bit);
 }
 // XXX end - verification code; only works while we also mark in object headers
 #ifndef PRODUCT
 const char* PSParallelCompact::space_names[] = {
   "perm", "old ", "eden", "from", "to  "
 };
 void PSParallelCompact::print_chunk_ranges()
 {
   tty->print_cr("space  bottom     top        end        new_top");
   tty->print_cr("------ ---------- ---------- ---------- ----------");
   for (unsigned int id = 0; id < last_space_id; ++id) {
     const MutableSpace* space = _space_info[id].space();
     tty->print_cr("%u %s "
                   SIZE_FORMAT_W("10") " " SIZE_FORMAT_W("10") " "
                   SIZE_FORMAT_W("10") " " SIZE_FORMAT_W("10") " ",
                   id, space_names[id],
                   summary_data().addr_to_chunk_idx(space->bottom()),
                   summary_data().addr_to_chunk_idx(space->top()),
                   summary_data().addr_to_chunk_idx(space->end()),
                   summary_data().addr_to_chunk_idx(_space_info[id].new_top()));
   }
 }
 void
 print_generic_summary_chunk(size_t i, const ParallelCompactData::ChunkData* c)
 {
 #define CHUNK_IDX_FORMAT        SIZE_FORMAT_W("7")
 #define CHUNK_DATA_FORMAT       SIZE_FORMAT_W("5")
   ParallelCompactData& sd = PSParallelCompact::summary_data();
   size_t dci = c->destination() ? sd.addr_to_chunk_idx(c->destination()) : 0;
   tty->print_cr(CHUNK_IDX_FORMAT " " PTR_FORMAT " "
                 CHUNK_IDX_FORMAT " " PTR_FORMAT " "
                 CHUNK_DATA_FORMAT " " CHUNK_DATA_FORMAT " "
                 CHUNK_DATA_FORMAT " " CHUNK_IDX_FORMAT " %d",
                 i, c->data_location(), dci, c->destination(),
                 c->partial_obj_size(), c->live_obj_size(),
                 c->data_size(), c->source_chunk(), c->destination_count());
 #undef  CHUNK_IDX_FORMAT
 #undef  CHUNK_DATA_FORMAT
 }
 void
 print_generic_summary_data(ParallelCompactData& summary_data,
                            HeapWord* const beg_addr,
                            HeapWord* const end_addr)
 {
   size_t total_words = 0;
   size_t i = summary_data.addr_to_chunk_idx(beg_addr);
   const size_t last = summary_data.addr_to_chunk_idx(end_addr);
   HeapWord* pdest = 0;
   while (i <= last) {
     ParallelCompactData::ChunkData* c = summary_data.chunk(i);
     if (c->data_size() != 0 || c->destination() != pdest) {
       print_generic_summary_chunk(i, c);
       total_words += c->data_size();
       pdest = c->destination();
     }
     ++i;
   }
   tty->print_cr("summary_data_bytes=" SIZE_FORMAT, total_words * HeapWordSize);
 }
 void
 print_generic_summary_data(ParallelCompactData& summary_data,
                            SpaceInfo* space_info)
 {
   for (unsigned int id = 0; id < PSParallelCompact::last_space_id; ++id) {
     const MutableSpace* space = space_info[id].space();
     print_generic_summary_data(summary_data, space->bottom(),
                                MAX2(space->top(), space_info[id].new_top()));
   }
 }
 void
 print_initial_summary_chunk(size_t i,
                             const ParallelCompactData::ChunkData* c,
                             bool newline = true)
 {
   tty->print(SIZE_FORMAT_W("5") " " PTR_FORMAT " "
              SIZE_FORMAT_W("5") " " SIZE_FORMAT_W("5") " "
              SIZE_FORMAT_W("5") " " SIZE_FORMAT_W("5") " %d",
              i, c->destination(),
              c->partial_obj_size(), c->live_obj_size(),
              c->data_size(), c->source_chunk(), c->destination_count());
   if (newline) tty->cr();
 }
 void
 print_initial_summary_data(ParallelCompactData& summary_data,
                            const MutableSpace* space) {
   if (space->top() == space->bottom()) {
     return;
   }
   const size_t chunk_size = ParallelCompactData::ChunkSize;
   HeapWord* const top_aligned_up = summary_data.chunk_align_up(space->top());
   const size_t end_chunk = summary_data.addr_to_chunk_idx(top_aligned_up);
   const ParallelCompactData::ChunkData* c = summary_data.chunk(end_chunk - 1);
   HeapWord* end_addr = c->destination() + c->data_size();
   const size_t live_in_space = pointer_delta(end_addr, space->bottom());
   // Print (and count) the full chunks at the beginning of the space.
   size_t full_chunk_count = 0;
   size_t i = summary_data.addr_to_chunk_idx(space->bottom());
   while (i < end_chunk && summary_data.chunk(i)->data_size() == chunk_size) {
     print_initial_summary_chunk(i, summary_data.chunk(i));
     ++full_chunk_count;
     ++i;
   }
   size_t live_to_right = live_in_space - full_chunk_count * chunk_size;
   double max_reclaimed_ratio = 0.0;
   size_t max_reclaimed_ratio_chunk = 0;
   size_t max_dead_to_right = 0;
   size_t max_live_to_right = 0;
   // Print the 'reclaimed ratio' for chunks while there is something live in the
   // chunk or to the right of it.  The remaining chunks are empty (and
   // uninteresting), and computing the ratio will result in division by 0.
   while (i < end_chunk && live_to_right > 0) {
     c = summary_data.chunk(i);
     HeapWord* const chunk_addr = summary_data.chunk_to_addr(i);
     const size_t used_to_right = pointer_delta(space->top(), chunk_addr);
     const size_t dead_to_right = used_to_right - live_to_right;
     const double reclaimed_ratio = double(dead_to_right) / live_to_right;
     if (reclaimed_ratio > max_reclaimed_ratio) {
             max_reclaimed_ratio = reclaimed_ratio;
             max_reclaimed_ratio_chunk = i;
             max_dead_to_right = dead_to_right;
             max_live_to_right = live_to_right;
     }
     print_initial_summary_chunk(i, c, false);
     tty->print_cr(" %12.10f " SIZE_FORMAT_W("10") " " SIZE_FORMAT_W("10"),
                   reclaimed_ratio, dead_to_right, live_to_right);
     live_to_right -= c->data_size();
     ++i;
   }
   // Any remaining chunks are empty.  Print one more if there is one.
   if (i < end_chunk) {
     print_initial_summary_chunk(i, summary_data.chunk(i));
   }
   tty->print_cr("max:  " SIZE_FORMAT_W("4") " d2r=" SIZE_FORMAT_W("10") " "
                 "l2r=" SIZE_FORMAT_W("10") " max_ratio=%14.12f",
                 max_reclaimed_ratio_chunk, max_dead_to_right,
                 max_live_to_right, max_reclaimed_ratio);
 }
 void
 print_initial_summary_data(ParallelCompactData& summary_data,
                            SpaceInfo* space_info) {
   unsigned int id = PSParallelCompact::perm_space_id;
   const MutableSpace* space;
   do {
     space = space_info[id].space();
     print_initial_summary_data(summary_data, space);
   } while (++id < PSParallelCompact::eden_space_id);
   do {
     space = space_info[id].space();
     print_generic_summary_data(summary_data, space->bottom(), space->top());
   } while (++id < PSParallelCompact::last_space_id);
 }
 #endif  // #ifndef PRODUCT
 #ifdef  ASSERT
 size_t add_obj_count;
 size_t add_obj_size;
 size_t mark_bitmap_count;
 size_t mark_bitmap_size;
 #endif  // #ifdef ASSERT
 ParallelCompactData::ParallelCompactData()
 {
   _region_start = 0;
   _chunk_vspace = 0;
   _chunk_data = 0;
   _chunk_count = 0;
   _block_vspace = 0;
   _block_data = 0;
   _block_count = 0;
 }
 bool ParallelCompactData::initialize(MemRegion covered_region)
 {
   _region_start = covered_region.start();
   const size_t region_size = covered_region.word_size();
   DEBUG_ONLY(_region_end = _region_start + region_size;)
   assert(chunk_align_down(_region_start) == _region_start,
          "region start not aligned");
   assert((region_size & ChunkSizeOffsetMask) == 0,
          "region size not a multiple of ChunkSize");
   bool result = initialize_chunk_data(region_size);
   // Initialize the block data if it will be used for updating pointers, or if
   // this is a debug build.
   if (!UseParallelOldGCChunkPointerCalc || trueInDebug) {
     result = result && initialize_block_data(region_size);
   }
   return result;
 }
 PSVirtualSpace*
 ParallelCompactData::create_vspace(size_t count, size_t element_size)
 {
   const size_t raw_bytes = count * element_size;
   const size_t page_sz = os::page_size_for_region(raw_bytes, raw_bytes, 10);
   const size_t granularity = os::vm_allocation_granularity();
   const size_t bytes = align_size_up(raw_bytes, MAX2(page_sz, granularity));
   const size_t rs_align = page_sz == (size_t) os::vm_page_size() ? 0 :
     MAX2(page_sz, granularity);
   ReservedSpace rs(bytes, rs_align, rs_align > 0);
   os::trace_page_sizes("par compact", raw_bytes, raw_bytes, page_sz, rs.base(),
                        rs.size());
   PSVirtualSpace* vspace = new PSVirtualSpace(rs, page_sz);
   if (vspace != 0) {
     if (vspace->expand_by(bytes)) {
       return vspace;
     }
     delete vspace;
     // Release memory reserved in the space.
     rs.release();
   }
   return 0;
 }
 bool ParallelCompactData::initialize_chunk_data(size_t region_size)
 {
   const size_t count = (region_size + ChunkSizeOffsetMask) >> Log2ChunkSize;
   _chunk_vspace = create_vspace(count, sizeof(ChunkData));
   if (_chunk_vspace != 0) {
     _chunk_data = (ChunkData*)_chunk_vspace->reserved_low_addr();
     _chunk_count = count;
     return true;
   }
   return false;
 }
 bool ParallelCompactData::initialize_block_data(size_t region_size)
 {
   const size_t count = (region_size + BlockOffsetMask) >> Log2BlockSize;
   _block_vspace = create_vspace(count, sizeof(BlockData));
   if (_block_vspace != 0) {
     _block_data = (BlockData*)_block_vspace->reserved_low_addr();
     _block_count = count;
     return true;
   }
   return false;
 }
 void ParallelCompactData::clear()
 {
   if (_block_data) {
     memset(_block_data, 0, _block_vspace->committed_size());
   }
   memset(_chunk_data, 0, _chunk_vspace->committed_size());
 }
 void ParallelCompactData::clear_range(size_t beg_chunk, size_t end_chunk) {
   assert(beg_chunk <= _chunk_count, "beg_chunk out of range");
   assert(end_chunk <= _chunk_count, "end_chunk out of range");
   assert(ChunkSize % BlockSize == 0, "ChunkSize not a multiple of BlockSize");
   const size_t chunk_cnt = end_chunk - beg_chunk;
   if (_block_data) {
     const size_t blocks_per_chunk = ChunkSize / BlockSize;
     const size_t beg_block = beg_chunk * blocks_per_chunk;
     const size_t block_cnt = chunk_cnt * blocks_per_chunk;
     memset(_block_data + beg_block, 0, block_cnt * sizeof(BlockData));
   }
   memset(_chunk_data + beg_chunk, 0, chunk_cnt * sizeof(ChunkData));
 }
 HeapWord* ParallelCompactData::partial_obj_end(size_t chunk_idx) const
 {
   const ChunkData* cur_cp = chunk(chunk_idx);
   const ChunkData* const end_cp = chunk(chunk_count() - 1);
   HeapWord* result = chunk_to_addr(chunk_idx);
   if (cur_cp < end_cp) {
     do {
       result += cur_cp->partial_obj_size();
     } while (cur_cp->partial_obj_size() == ChunkSize && ++cur_cp < end_cp);
   }
   return result;
 }
 void ParallelCompactData::add_obj(HeapWord* addr, size_t len)
 {
   const size_t obj_ofs = pointer_delta(addr, _region_start);
   const size_t beg_chunk = obj_ofs >> Log2ChunkSize;
   const size_t end_chunk = (obj_ofs + len - 1) >> Log2ChunkSize;
   DEBUG_ONLY(Atomic::inc_ptr(&add_obj_count);)
   DEBUG_ONLY(Atomic::add_ptr(len, &add_obj_size);)
   if (beg_chunk == end_chunk) {
     // All in one chunk.
     _chunk_data[beg_chunk].add_live_obj(len);
     return;
   }
   // First chunk.
   const size_t beg_ofs = chunk_offset(addr);
   _chunk_data[beg_chunk].add_live_obj(ChunkSize - beg_ofs);
   klassOop klass = ((oop)addr)->klass();
   // Middle chunks--completely spanned by this object.
   for (size_t chunk = beg_chunk + 1; chunk < end_chunk; ++chunk) {
     _chunk_data[chunk].set_partial_obj_size(ChunkSize);
     _chunk_data[chunk].set_partial_obj_addr(addr);
   }
   // Last chunk.
   const size_t end_ofs = chunk_offset(addr + len - 1);
   _chunk_data[end_chunk].set_partial_obj_size(end_ofs + 1);
   _chunk_data[end_chunk].set_partial_obj_addr(addr);
 }
 void
 ParallelCompactData::summarize_dense_prefix(HeapWord* beg, HeapWord* end)
 {
   assert(chunk_offset(beg) == 0, "not ChunkSize aligned");
   assert(chunk_offset(end) == 0, "not ChunkSize aligned");
   size_t cur_chunk = addr_to_chunk_idx(beg);
   const size_t end_chunk = addr_to_chunk_idx(end);
   HeapWord* addr = beg;
   while (cur_chunk < end_chunk) {
     _chunk_data[cur_chunk].set_destination(addr);
     _chunk_data[cur_chunk].set_destination_count(0);
     _chunk_data[cur_chunk].set_source_chunk(cur_chunk);
     _chunk_data[cur_chunk].set_data_location(addr);
     // Update live_obj_size so the chunk appears completely full.
     size_t live_size = ChunkSize - _chunk_data[cur_chunk].partial_obj_size();
     _chunk_data[cur_chunk].set_live_obj_size(live_size);
     ++cur_chunk;
     addr += ChunkSize;
   }
 }
 bool ParallelCompactData::summarize(HeapWord* target_beg, HeapWord* target_end,
                                     HeapWord* source_beg, HeapWord* source_end,
                                     HeapWord** target_next,
                                     HeapWord** source_next) {
   // This is too strict.
   // assert(chunk_offset(source_beg) == 0, "not ChunkSize aligned");
   if (TraceParallelOldGCSummaryPhase) {
     tty->print_cr("tb=" PTR_FORMAT " te=" PTR_FORMAT " "
                   "sb=" PTR_FORMAT " se=" PTR_FORMAT " "
                   "tn=" PTR_FORMAT " sn=" PTR_FORMAT,
                   target_beg, target_end,
                   source_beg, source_end,
                   target_next != 0 ? *target_next : (HeapWord*) 0,
                   source_next != 0 ? *source_next : (HeapWord*) 0);
   }
   size_t cur_chunk = addr_to_chunk_idx(source_beg);
   const size_t end_chunk = addr_to_chunk_idx(chunk_align_up(source_end));
   HeapWord *dest_addr = target_beg;
   while (cur_chunk < end_chunk) {
     size_t words = _chunk_data[cur_chunk].data_size();
 #if     1
     assert(pointer_delta(target_end, dest_addr) >= words,
            "source region does not fit into target region");
 #else
     // XXX - need some work on the corner cases here.  If the chunk does not
     // fit, then must either make sure any partial_obj from the chunk fits, or
     // 'undo' the initial part of the partial_obj that is in the previous chunk.
     if (dest_addr + words >= target_end) {
       // Let the caller know where to continue.
       *target_next = dest_addr;
       *source_next = chunk_to_addr(cur_chunk);
       return false;
     }
 #endif  // #if 1
     _chunk_data[cur_chunk].set_destination(dest_addr);
     // Set the destination_count for cur_chunk, and if necessary, update
     // source_chunk for a destination chunk.  The source_chunk field is updated
     // if cur_chunk is the first (left-most) chunk to be copied to a destination
     // chunk.
     //
     // The destination_count calculation is a bit subtle.  A chunk that has data
     // that compacts into itself does not count itself as a destination.  This
     // maintains the invariant that a zero count means the chunk is available
     // and can be claimed and then filled.
     if (words > 0) {
       HeapWord* const last_addr = dest_addr + words - 1;
       const size_t dest_chunk_1 = addr_to_chunk_idx(dest_addr);
       const size_t dest_chunk_2 = addr_to_chunk_idx(last_addr);
 #if     0
       // Initially assume that the destination chunks will be the same and
       // adjust the value below if necessary.  Under this assumption, if
       // cur_chunk == dest_chunk_2, then cur_chunk will be compacted completely
       // into itself.
       uint destination_count = cur_chunk == dest_chunk_2 ? 0 : 1;
       if (dest_chunk_1 != dest_chunk_2) {
         // Destination chunks differ; adjust destination_count.
         destination_count += 1;
         // Data from cur_chunk will be copied to the start of dest_chunk_2.
         _chunk_data[dest_chunk_2].set_source_chunk(cur_chunk);
       } else if (chunk_offset(dest_addr) == 0) {
         // Data from cur_chunk will be copied to the start of the destination
         // chunk.
         _chunk_data[dest_chunk_1].set_source_chunk(cur_chunk);
       }
 #else
       // Initially assume that the destination chunks will be different and
       // adjust the value below if necessary.  Under this assumption, if
       // cur_chunk == dest_chunk2, then cur_chunk will be compacted partially
       // into dest_chunk_1 and partially into itself.
       uint destination_count = cur_chunk == dest_chunk_2 ? 1 : 2;
       if (dest_chunk_1 != dest_chunk_2) {
         // Data from cur_chunk will be copied to the start of dest_chunk_2.
         _chunk_data[dest_chunk_2].set_source_chunk(cur_chunk);
       } else {
         // Destination chunks are the same; adjust destination_count.
         destination_count -= 1;
         if (chunk_offset(dest_addr) == 0) {
           // Data from cur_chunk will be copied to the start of the destination
           // chunk.
           _chunk_data[dest_chunk_1].set_source_chunk(cur_chunk);
         }
       }
 #endif  // #if 0
       _chunk_data[cur_chunk].set_destination_count(destination_count);
       _chunk_data[cur_chunk].set_data_location(chunk_to_addr(cur_chunk));
       dest_addr += words;
     }
     ++cur_chunk;
   }
   *target_next = dest_addr;
   return true;
 }
 bool ParallelCompactData::partial_obj_ends_in_block(size_t block_index) {
   HeapWord* block_addr = block_to_addr(block_index);
   HeapWord* block_end_addr = block_addr + BlockSize;
   size_t chunk_index = addr_to_chunk_idx(block_addr);
   HeapWord* partial_obj_end_addr = partial_obj_end(chunk_index);
   // An object that ends at the end of the block, ends
   // in the block (the last word of the object is to
   // the left of the end).
   if ((block_addr < partial_obj_end_addr) &&
       (partial_obj_end_addr <= block_end_addr)) {
     return true;
   }
   return false;
 }
 HeapWord* ParallelCompactData::calc_new_pointer(HeapWord* addr) {
   HeapWord* result = NULL;
   if (UseParallelOldGCChunkPointerCalc) {
     result = chunk_calc_new_pointer(addr);
   } else {
     result = block_calc_new_pointer(addr);
   }
   return result;
 }
 // This method is overly complicated (expensive) to be called
 // for every reference.
 // Try to restructure this so that a NULL is returned if
 // the object is dead.  But don't wast the cycles to explicitly check
 // that it is dead since only live objects should be passed in.
 HeapWord* ParallelCompactData::chunk_calc_new_pointer(HeapWord* addr) {
   assert(addr != NULL, "Should detect NULL oop earlier");
   assert(PSParallelCompact::gc_heap()->is_in(addr), "addr not in heap");
 #ifdef ASSERT
   if (PSParallelCompact::mark_bitmap()->is_unmarked(addr)) {
     gclog_or_tty->print_cr("calc_new_pointer:: addr " PTR_FORMAT, addr);
   }
 #endif
   assert(PSParallelCompact::mark_bitmap()->is_marked(addr), "obj not marked");
   // Chunk covering the object.
   size_t chunk_index = addr_to_chunk_idx(addr);
   const ChunkData* const chunk_ptr = chunk(chunk_index);
   HeapWord* const chunk_addr = chunk_align_down(addr);
   assert(addr < chunk_addr + ChunkSize, "Chunk does not cover object");
   assert(addr_to_chunk_ptr(chunk_addr) == chunk_ptr, "sanity check");
   HeapWord* result = chunk_ptr->destination();
   // If all the data in the chunk is live, then the new location of the object
   // can be calculated from the destination of the chunk plus the offset of the
   // object in the chunk.
   if (chunk_ptr->data_size() == ChunkSize) {
     result += pointer_delta(addr, chunk_addr);
     return result;
   }
   // The new location of the object is
   //    chunk destination +
   //    size of the partial object extending onto the chunk +
   //    sizes of the live objects in the Chunk that are to the left of addr
   const size_t partial_obj_size = chunk_ptr->partial_obj_size();
   HeapWord* const search_start = chunk_addr + partial_obj_size;
   const ParMarkBitMap* bitmap = PSParallelCompact::mark_bitmap();
   size_t live_to_left = bitmap->live_words_in_range(search_start, oop(addr));
   result += partial_obj_size + live_to_left;
   assert(result <= addr, "object cannot move to the right");
   return result;
 }
 HeapWord* ParallelCompactData::block_calc_new_pointer(HeapWord* addr) {
   assert(addr != NULL, "Should detect NULL oop earlier");
   assert(PSParallelCompact::gc_heap()->is_in(addr), "addr not in heap");
 #ifdef ASSERT
   if (PSParallelCompact::mark_bitmap()->is_unmarked(addr)) {
     gclog_or_tty->print_cr("calc_new_pointer:: addr " PTR_FORMAT, addr);
   }
 #endif
   assert(PSParallelCompact::mark_bitmap()->is_marked(addr), "obj not marked");
   // Chunk covering the object.
   size_t chunk_index = addr_to_chunk_idx(addr);
   const ChunkData* const chunk_ptr = chunk(chunk_index);
   HeapWord* const chunk_addr = chunk_align_down(addr);
   assert(addr < chunk_addr + ChunkSize, "Chunk does not cover object");
   assert(addr_to_chunk_ptr(chunk_addr) == chunk_ptr, "sanity check");
   HeapWord* result = chunk_ptr->destination();
   // If all the data in the chunk is live, then the new location of the object
   // can be calculated from the destination of the chunk plus the offset of the
   // object in the chunk.
   if (chunk_ptr->data_size() == ChunkSize) {
     result += pointer_delta(addr, chunk_addr);
     return result;
   }
   // The new location of the object is
   //    chunk destination +
   //    block offset +
   //    sizes of the live objects in the Block that are to the left of addr
   const size_t block_offset = addr_to_block_ptr(addr)->offset();
   HeapWord* const search_start = chunk_addr + block_offset;
   const ParMarkBitMap* bitmap = PSParallelCompact::mark_bitmap();
   size_t live_to_left = bitmap->live_words_in_range(search_start, oop(addr));
   result += block_offset + live_to_left;
   assert(result <= addr, "object cannot move to the right");
   assert(result == chunk_calc_new_pointer(addr), "Should match");
   return result;
 }
 klassOop ParallelCompactData::calc_new_klass(klassOop old_klass) {
   klassOop updated_klass;
   if (PSParallelCompact::should_update_klass(old_klass)) {
     updated_klass = (klassOop) calc_new_pointer(old_klass);
   } else {
     updated_klass = old_klass;
   }
   return updated_klass;
 }
 #ifdef  ASSERT
 void ParallelCompactData::verify_clear(const PSVirtualSpace* vspace)
 {
   const size_t* const beg = (const size_t*)vspace->committed_low_addr();
   const size_t* const end = (const size_t*)vspace->committed_high_addr();
   for (const size_t* p = beg; p < end; ++p) {
     assert(*p == 0, "not zero");
   }
 }
 void ParallelCompactData::verify_clear()
 {
   verify_clear(_chunk_vspace);
   verify_clear(_block_vspace);
 }
 #endif  // #ifdef ASSERT
 #ifdef NOT_PRODUCT
 ParallelCompactData::ChunkData* debug_chunk(size_t chunk_index) {
   ParallelCompactData& sd = PSParallelCompact::summary_data();
   return sd.chunk(chunk_index);
 }
 #endif
 elapsedTimer        PSParallelCompact::_accumulated_time;
 unsigned int        PSParallelCompact::_total_invocations = 0;
 unsigned int        PSParallelCompact::_maximum_compaction_gc_num = 0;
 jlong               PSParallelCompact::_time_of_last_gc = 0;
 CollectorCounters*  PSParallelCompact::_counters = NULL;
 ParMarkBitMap       PSParallelCompact::_mark_bitmap;
 ParallelCompactData PSParallelCompact::_summary_data;
 PSParallelCompact::IsAliveClosure PSParallelCompact::_is_alive_closure;
 void PSParallelCompact::IsAliveClosure::do_object(oop p)   { ShouldNotReachHere(); }
 bool PSParallelCompact::IsAliveClosure::do_object_b(oop p) { return mark_bitmap()->is_marked(p); }
 void PSParallelCompact::KeepAliveClosure::do_oop(oop* p)       { PSParallelCompact::KeepAliveClosure::do_oop_work(p); }
 void PSParallelCompact::KeepAliveClosure::do_oop(narrowOop* p) { PSParallelCompact::KeepAliveClosure::do_oop_work(p); }
 PSParallelCompact::AdjustPointerClosure PSParallelCompact::_adjust_root_pointer_closure(true);
 PSParallelCompact::AdjustPointerClosure PSParallelCompact::_adjust_pointer_closure(false);
 void PSParallelCompact::AdjustPointerClosure::do_oop(oop* p)       { adjust_pointer(p, _is_root); }
 void PSParallelCompact::AdjustPointerClosure::do_oop(narrowOop* p) { adjust_pointer(p, _is_root); }
 void PSParallelCompact::FollowStackClosure::do_void() { follow_stack(_compaction_manager); }
 void PSParallelCompact::MarkAndPushClosure::do_oop(oop* p)       { mark_and_push(_compaction_manager, p); }
 void PSParallelCompact::MarkAndPushClosure::do_oop(narrowOop* p) { mark_and_push(_compaction_manager, p); }
 void PSParallelCompact::post_initialize() {
   ParallelScavengeHeap* heap = gc_heap();
   assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
   MemRegion mr = heap->reserved_region();
   _ref_processor = ReferenceProcessor::create_ref_processor(
     mr,                         // span
     true,                       // atomic_discovery
     true,                       // mt_discovery
     &_is_alive_closure,
     ParallelGCThreads,
     ParallelRefProcEnabled);
   _counters = new CollectorCounters("PSParallelCompact", 1);
   // Initialize static fields in ParCompactionManager.
   ParCompactionManager::initialize(mark_bitmap());
 }
 bool PSParallelCompact::initialize() {
   ParallelScavengeHeap* heap = gc_heap();
   assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
   MemRegion mr = heap->reserved_region();
   // Was the old gen get allocated successfully?
   if (!heap->old_gen()->is_allocated()) {
     return false;
   }
   initialize_space_info();
   initialize_dead_wood_limiter();
   if (!_mark_bitmap.initialize(mr)) {
     vm_shutdown_during_initialization("Unable to allocate bit map for "
       "parallel garbage collection for the requested heap size.");
     return false;
   }
   if (!_summary_data.initialize(mr)) {
     vm_shutdown_during_initialization("Unable to allocate tables for "
       "parallel garbage collection for the requested heap size.");
     return false;
   }
   return true;
 }
 void PSParallelCompact::initialize_space_info()
 {
   memset(&_space_info, 0, sizeof(_space_info));
   ParallelScavengeHeap* heap = gc_heap();
   PSYoungGen* young_gen = heap->young_gen();
   MutableSpace* perm_space = heap->perm_gen()->object_space();
   _space_info[perm_space_id].set_space(perm_space);
   _space_info[old_space_id].set_space(heap->old_gen()->object_space());
   _space_info[eden_space_id].set_space(young_gen->eden_space());
   _space_info[from_space_id].set_space(young_gen->from_space());
   _space_info[to_space_id].set_space(young_gen->to_space());
   _space_info[perm_space_id].set_start_array(heap->perm_gen()->start_array());
   _space_info[old_space_id].set_start_array(heap->old_gen()->start_array());
   _space_info[perm_space_id].set_min_dense_prefix(perm_space->top());
   if (TraceParallelOldGCDensePrefix) {
     tty->print_cr("perm min_dense_prefix=" PTR_FORMAT,
                   _space_info[perm_space_id].min_dense_prefix());
   }
 }
 void PSParallelCompact::initialize_dead_wood_limiter()
 {
   const size_t max = 100;
   _dwl_mean = double(MIN2(ParallelOldDeadWoodLimiterMean, max)) / 100.0;
   _dwl_std_dev = double(MIN2(ParallelOldDeadWoodLimiterStdDev, max)) / 100.0;
   _dwl_first_term = 1.0 / (sqrt(2.0 * M_PI) * _dwl_std_dev);
   DEBUG_ONLY(_dwl_initialized = true;)
   _dwl_adjustment = normal_distribution(1.0);
 }
 // Simple class for storing info about the heap at the start of GC, to be used
 // after GC for comparison/printing.
 class PreGCValues {
 public:
   PreGCValues() { }
   PreGCValues(ParallelScavengeHeap* heap) { fill(heap); }
   void fill(ParallelScavengeHeap* heap) {
     _heap_used      = heap->used();
     _young_gen_used = heap->young_gen()->used_in_bytes();
     _old_gen_used   = heap->old_gen()->used_in_bytes();
     _perm_gen_used  = heap->perm_gen()->used_in_bytes();
   };
   size_t heap_used() const      { return _heap_used; }
   size_t young_gen_used() const { return _young_gen_used; }
   size_t old_gen_used() const   { return _old_gen_used; }
   size_t perm_gen_used() const  { return _perm_gen_used; }
 private:
   size_t _heap_used;
   size_t _young_gen_used;
   size_t _old_gen_used;
   size_t _perm_gen_used;
 };
 void
 PSParallelCompact::clear_data_covering_space(SpaceId id)
 {
   // At this point, top is the value before GC, new_top() is the value that will
   // be set at the end of GC.  The marking bitmap is cleared to top; nothing
   // should be marked above top.  The summary data is cleared to the larger of
   // top & new_top.
   MutableSpace* const space = _space_info[id].space();
   HeapWord* const bot = space->bottom();
   HeapWord* const top = space->top();
   HeapWord* const max_top = MAX2(top, _space_info[id].new_top());
   const idx_t beg_bit = _mark_bitmap.addr_to_bit(bot);
   const idx_t end_bit = BitMap::word_align_up(_mark_bitmap.addr_to_bit(top));
   _mark_bitmap.clear_range(beg_bit, end_bit);
   const size_t beg_chunk = _summary_data.addr_to_chunk_idx(bot);
   const size_t end_chunk =
     _summary_data.addr_to_chunk_idx(_summary_data.chunk_align_up(max_top));
   _summary_data.clear_range(beg_chunk, end_chunk);
 }
 void PSParallelCompact::pre_compact(PreGCValues* pre_gc_values)
 {
   // Update the from & to space pointers in space_info, since they are swapped
   // at each young gen gc.  Do the update unconditionally (even though a
   // promotion failure does not swap spaces) because an unknown number of minor
   // collections will have swapped the spaces an unknown number of times.
   TraceTime tm("pre compact", print_phases(), true, gclog_or_tty);
   ParallelScavengeHeap* heap = gc_heap();
   _space_info[from_space_id].set_space(heap->young_gen()->from_space());
   _space_info[to_space_id].set_space(heap->young_gen()->to_space());
   pre_gc_values->fill(heap);
   ParCompactionManager::reset();
   NOT_PRODUCT(_mark_bitmap.reset_counters());
   DEBUG_ONLY(add_obj_count = add_obj_size = 0;)
   DEBUG_ONLY(mark_bitmap_count = mark_bitmap_size = 0;)
   // Increment the invocation count
   heap->increment_total_collections(true);
   // We need to track unique mark sweep invocations as well.
   _total_invocations++;
   if (PrintHeapAtGC) {
     Universe::print_heap_before_gc();
   }
   // Fill in TLABs
   heap->accumulate_statistics_all_tlabs();
   heap->ensure_parsability(true);  // retire TLABs
   if (VerifyBeforeGC && heap->total_collections() >= VerifyGCStartAt) {
     HandleMark hm;  // Discard invalid handles created during verification
     gclog_or_tty->print(" VerifyBeforeGC:");
     Universe::verify(true);
   }
   // Verify object start arrays
   if (VerifyObjectStartArray &&
       VerifyBeforeGC) {
     heap->old_gen()->verify_object_start_array();
     heap->perm_gen()->verify_object_start_array();
   }
   DEBUG_ONLY(mark_bitmap()->verify_clear();)
   DEBUG_ONLY(summary_data().verify_clear();)
   // Have worker threads release resources the next time they run a task.
   gc_task_manager()->release_all_resources();
 }
 void PSParallelCompact::post_compact()
 {
   TraceTime tm("post compact", print_phases(), true, gclog_or_tty);
   // Clear the marking bitmap and summary data and update top() in each space.
   for (unsigned int id = perm_space_id; id < last_space_id; ++id) {
     clear_data_covering_space(SpaceId(id));
     _space_info[id].space()->set_top(_space_info[id].new_top());
   }
   MutableSpace* const eden_space = _space_info[eden_space_id].space();
   MutableSpace* const from_space = _space_info[from_space_id].space();
   MutableSpace* const to_space   = _space_info[to_space_id].space();
   ParallelScavengeHeap* heap = gc_heap();
   bool eden_empty = eden_space->is_empty();
   if (!eden_empty) {
     eden_empty = absorb_live_data_from_eden(heap->size_policy(),
                                             heap->young_gen(), heap->old_gen());
   }
   // Update heap occupancy information which is used as input to the soft ref
   // clearing policy at the next gc.
   Universe::update_heap_info_at_gc();
   bool young_gen_empty = eden_empty && from_space->is_empty() &&
     to_space->is_empty();
   BarrierSet* bs = heap->barrier_set();
   if (bs->is_a(BarrierSet::ModRef)) {
     ModRefBarrierSet* modBS = (ModRefBarrierSet*)bs;
     MemRegion old_mr = heap->old_gen()->reserved();
     MemRegion perm_mr = heap->perm_gen()->reserved();
     assert(perm_mr.end() <= old_mr.start(), "Generations out of order");
     if (young_gen_empty) {
       modBS->clear(MemRegion(perm_mr.start(), old_mr.end()));
     } else {
       modBS->invalidate(MemRegion(perm_mr.start(), old_mr.end()));
     }
   }
   Threads::gc_epilogue();
   CodeCache::gc_epilogue();
   COMPILER2_PRESENT(DerivedPointerTable::update_pointers());
   ref_processor()->enqueue_discovered_references(NULL);
   // Update time of last GC
   reset_millis_since_last_gc();
 }
 HeapWord*
 PSParallelCompact::compute_dense_prefix_via_density(const SpaceId id,
                                                     bool maximum_compaction)
 {
   const size_t chunk_size = ParallelCompactData::ChunkSize;
   const ParallelCompactData& sd = summary_data();
   const MutableSpace* const space = _space_info[id].space();
   HeapWord* const top_aligned_up = sd.chunk_align_up(space->top());
   const ChunkData* const beg_cp = sd.addr_to_chunk_ptr(space->bottom());
   const ChunkData* const end_cp = sd.addr_to_chunk_ptr(top_aligned_up);
   // Skip full chunks at the beginning of the space--they are necessarily part
   // of the dense prefix.
   size_t full_count = 0;
   const ChunkData* cp;
   for (cp = beg_cp; cp < end_cp && cp->data_size() == chunk_size; ++cp) {
     ++full_count;
   }
   assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");
   const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;
   const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval;
   if (maximum_compaction || cp == end_cp || interval_ended) {
     _maximum_compaction_gc_num = total_invocations();
     return sd.chunk_to_addr(cp);
   }
   HeapWord* const new_top = _space_info[id].new_top();
   const size_t space_live = pointer_delta(new_top, space->bottom());
   const size_t space_used = space->used_in_words();
   const size_t space_capacity = space->capacity_in_words();
   const double cur_density = double(space_live) / space_capacity;
   const double deadwood_density =
     (1.0 - cur_density) * (1.0 - cur_density) * cur_density * cur_density;
   const size_t deadwood_goal = size_t(space_capacity * deadwood_density);
   if (TraceParallelOldGCDensePrefix) {
     tty->print_cr("cur_dens=%5.3f dw_dens=%5.3f dw_goal=" SIZE_FORMAT,
                   cur_density, deadwood_density, deadwood_goal);
     tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " "
                   "space_cap=" SIZE_FORMAT,
                   space_live, space_used,
                   space_capacity);
   }
   // XXX - Use binary search?
   HeapWord* dense_prefix = sd.chunk_to_addr(cp);
   const ChunkData* full_cp = cp;
   const ChunkData* const top_cp = sd.addr_to_chunk_ptr(space->top() - 1);
   while (cp < end_cp) {
     HeapWord* chunk_destination = cp->destination();
     const size_t cur_deadwood = pointer_delta(dense_prefix, chunk_destination);
     if (TraceParallelOldGCDensePrefix && Verbose) {
       tty->print_cr("c#=" SIZE_FORMAT_W("04") " dst=" PTR_FORMAT " "
                     "dp=" SIZE_FORMAT_W("08") " " "cdw=" SIZE_FORMAT_W("08"),
                     sd.chunk(cp), chunk_destination,
                     dense_prefix, cur_deadwood);
     }
     if (cur_deadwood >= deadwood_goal) {
       // Found the chunk that has the correct amount of deadwood to the left.
       // This typically occurs after crossing a fairly sparse set of chunks, so
       // iterate backwards over those sparse chunks, looking for the chunk that
       // has the lowest density of live objects 'to the right.'
       size_t space_to_left = sd.chunk(cp) * chunk_size;
       size_t live_to_left = space_to_left - cur_deadwood;
       size_t space_to_right = space_capacity - space_to_left;
       size_t live_to_right = space_live - live_to_left;
       double density_to_right = double(live_to_right) / space_to_right;
       while (cp > full_cp) {
         --cp;
         const size_t prev_chunk_live_to_right = live_to_right - cp->data_size();
         const size_t prev_chunk_space_to_right = space_to_right + chunk_size;
         double prev_chunk_density_to_right =
           double(prev_chunk_live_to_right) / prev_chunk_space_to_right;
         if (density_to_right <= prev_chunk_density_to_right) {
           return dense_prefix;
         }
         if (TraceParallelOldGCDensePrefix && Verbose) {
           tty->print_cr("backing up from c=" SIZE_FORMAT_W("4") " d2r=%10.8f "
                         "pc_d2r=%10.8f", sd.chunk(cp), density_to_right,
                         prev_chunk_density_to_right);
         }
         dense_prefix -= chunk_size;
         live_to_right = prev_chunk_live_to_right;
         space_to_right = prev_chunk_space_to_right;
         density_to_right = prev_chunk_density_to_right;
       }
       return dense_prefix;
     }
     dense_prefix += chunk_size;
     ++cp;
   }
   return dense_prefix;
 }
 #ifndef PRODUCT
 void PSParallelCompact::print_dense_prefix_stats(const char* const algorithm,
                                                  const SpaceId id,
                                                  const bool maximum_compaction,
                                                  HeapWord* const addr)
 {
   const size_t chunk_idx = summary_data().addr_to_chunk_idx(addr);
   ChunkData* const cp = summary_data().chunk(chunk_idx);
   const MutableSpace* const space = _space_info[id].space();
   HeapWord* const new_top = _space_info[id].new_top();
   const size_t space_live = pointer_delta(new_top, space->bottom());
   const size_t dead_to_left = pointer_delta(addr, cp->destination());
   const size_t space_cap = space->capacity_in_words();
   const double dead_to_left_pct = double(dead_to_left) / space_cap;
   const size_t live_to_right = new_top - cp->destination();
   const size_t dead_to_right = space->top() - addr - live_to_right;
   tty->print_cr("%s=" PTR_FORMAT " dpc=" SIZE_FORMAT_W("05") " "
                 "spl=" SIZE_FORMAT " "
                 "d2l=" SIZE_FORMAT " d2l%%=%6.4f "
                 "d2r=" SIZE_FORMAT " l2r=" SIZE_FORMAT
                 " ratio=%10.8f",
                 algorithm, addr, chunk_idx,
                 space_live,
                 dead_to_left, dead_to_left_pct,
                 dead_to_right, live_to_right,
                 double(dead_to_right) / live_to_right);
 }
 #endif  // #ifndef PRODUCT
 // Return a fraction indicating how much of the generation can be treated as
 // "dead wood" (i.e., not reclaimed).  The function uses a normal distribution
 // based on the density of live objects in the generation to determine a limit,
 // which is then adjusted so the return value is min_percent when the density is
 // 1.
 //
 // The following table shows some return values for a different values of the
 // standard deviation (ParallelOldDeadWoodLimiterStdDev); the mean is 0.5 and
 // min_percent is 1.
 //
 //                          fraction allowed as dead wood
 //         -----------------------------------------------------------------
 // density std_dev=70 std_dev=75 std_dev=80 std_dev=85 std_dev=90 std_dev=95
 // ------- ---------- ---------- ---------- ---------- ---------- ----------
 // 0.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
 // 0.05000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
 // 0.10000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
 // 0.15000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
 // 0.20000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
 // 0.25000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
 // 0.30000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
 // 0.35000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
 // 0.40000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
 // 0.45000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
 // 0.50000 0.13832410 0.11599237 0.09847664 0.08456518 0.07338887 0.06431510
 // 0.55000 0.13687208 0.11481163 0.09750361 0.08375387 0.07270534 0.06373386
 // 0.60000 0.13253818 0.11128511 0.09459590 0.08132834 0.07066107 0.06199500
 // 0.65000 0.12538832 0.10545958 0.08978741 0.07731366 0.06727491 0.05911289
 // 0.70000 0.11553050 0.09741183 0.08313394 0.07175114 0.06257797 0.05511132
 // 0.75000 0.10311208 0.08724696 0.07471205 0.06469760 0.05661313 0.05002313
 // 0.80000 0.08831616 0.07509618 0.06461766 0.05622444 0.04943437 0.04388975
 // 0.85000 0.07135702 0.06111390 0.05296419 0.04641639 0.04110601 0.03676066
 // 0.90000 0.05247504 0.04547452 0.03988045 0.03537016 0.03170171 0.02869272
 // 0.95000 0.03193096 0.02836880 0.02550828 0.02319280 0.02130337 0.01974941
 // 1.00000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000 0.01000000
 double PSParallelCompact::dead_wood_limiter(double density, size_t min_percent)
 {
   assert(_dwl_initialized, "uninitialized");
   // The raw limit is the value of the normal distribution at x = density.
   const double raw_limit = normal_distribution(density);
   // Adjust the raw limit so it becomes the minimum when the density is 1.
   //
   // First subtract the adjustment value (which is simply the precomputed value
   // normal_distribution(1.0)); this yields a value of 0 when the density is 1.
   // Then add the minimum value, so the minimum is returned when the density is
   // 1.  Finally, prevent negative values, which occur when the mean is not 0.5.
   const double min = double(min_percent) / 100.0;
   const double limit = raw_limit - _dwl_adjustment + min;
   return MAX2(limit, 0.0);
 }
 ParallelCompactData::ChunkData*
 PSParallelCompact::first_dead_space_chunk(const ChunkData* beg,
                                           const ChunkData* end)
 {
   const size_t chunk_size = ParallelCompactData::ChunkSize;
   ParallelCompactData& sd = summary_data();
   size_t left = sd.chunk(beg);
   size_t right = end > beg ? sd.chunk(end) - 1 : left;
   // Binary search.
   while (left < right) {
     // Equivalent to (left + right) / 2, but does not overflow.
     const size_t middle = left + (right - left) / 2;
     ChunkData* const middle_ptr = sd.chunk(middle);
     HeapWord* const dest = middle_ptr->destination();
     HeapWord* const addr = sd.chunk_to_addr(middle);
     assert(dest != NULL, "sanity");
     assert(dest <= addr, "must move left");
     if (middle > left && dest < addr) {
       right = middle - 1;
     } else if (middle < right && middle_ptr->data_size() == chunk_size) {
       left = middle + 1;
     } else {
       return middle_ptr;
     }
   }
   return sd.chunk(left);
 }
 ParallelCompactData::ChunkData*
 PSParallelCompact::dead_wood_limit_chunk(const ChunkData* beg,
                                          const ChunkData* end,
                                          size_t dead_words)
 {
   ParallelCompactData& sd = summary_data();
   size_t left = sd.chunk(beg);
   size_t right = end > beg ? sd.chunk(end) - 1 : left;
   // Binary search.
   while (left < right) {
     // Equivalent to (left + right) / 2, but does not overflow.
     const size_t middle = left + (right - left) / 2;
     ChunkData* const middle_ptr = sd.chunk(middle);
     HeapWord* const dest = middle_ptr->destination();
     HeapWord* const addr = sd.chunk_to_addr(middle);
     assert(dest != NULL, "sanity");
     assert(dest <= addr, "must move left");
     const size_t dead_to_left = pointer_delta(addr, dest);
     if (middle > left && dead_to_left > dead_words) {
       right = middle - 1;
     } else if (middle < right && dead_to_left < dead_words) {
       left = middle + 1;
     } else {
       return middle_ptr;
     }
   }
   return sd.chunk(left);
 }
 // The result is valid during the summary phase, after the initial summarization
 // of each space into itself, and before final summarization.
 inline double
 PSParallelCompact::reclaimed_ratio(const ChunkData* const cp,
                                    HeapWord* const bottom,
                                    HeapWord* const top,
                                    HeapWord* const new_top)
 {
   ParallelCompactData& sd = summary_data();
   assert(cp != NULL, "sanity");
   assert(bottom != NULL, "sanity");
   assert(top != NULL, "sanity");
   assert(new_top != NULL, "sanity");
   assert(top >= new_top, "summary data problem?");
   assert(new_top > bottom, "space is empty; should not be here");
   assert(new_top >= cp->destination(), "sanity");
   assert(top >= sd.chunk_to_addr(cp), "sanity");
   HeapWord* const destination = cp->destination();
   const size_t dense_prefix_live  = pointer_delta(destination, bottom);
   const size_t compacted_region_live = pointer_delta(new_top, destination);
   const size_t compacted_region_used = pointer_delta(top, sd.chunk_to_addr(cp));
   const size_t reclaimable = compacted_region_used - compacted_region_live;
   const double divisor = dense_prefix_live + 1.25 * compacted_region_live;
   return double(reclaimable) / divisor;
 }
 // Return the address of the end of the dense prefix, a.k.a. the start of the
 // compacted region.  The address is always on a chunk boundary.
 //
 // Completely full chunks at the left are skipped, since no compaction can occur
 // in those chunks.  Then the maximum amount of dead wood to allow is computed,
 // based on the density (amount live / capacity) of the generation; the chunk
 // with approximately that amount of dead space to the left is identified as the
 // limit chunk.  Chunks between the last completely full chunk and the limit
 // chunk are scanned and the one that has the best (maximum) reclaimed_ratio()
 // is selected.
 HeapWord*
 PSParallelCompact::compute_dense_prefix(const SpaceId id,
                                         bool maximum_compaction)
 {
   const size_t chunk_size = ParallelCompactData::ChunkSize;
   const ParallelCompactData& sd = summary_data();
   const MutableSpace* const space = _space_info[id].space();
   HeapWord* const top = space->top();
   HeapWord* const top_aligned_up = sd.chunk_align_up(top);
   HeapWord* const new_top = _space_info[id].new_top();
   HeapWord* const new_top_aligned_up = sd.chunk_align_up(new_top);
   HeapWord* const bottom = space->bottom();
   const ChunkData* const beg_cp = sd.addr_to_chunk_ptr(bottom);
   const ChunkData* const top_cp = sd.addr_to_chunk_ptr(top_aligned_up);
   const ChunkData* const new_top_cp = sd.addr_to_chunk_ptr(new_top_aligned_up);
   // Skip full chunks at the beginning of the space--they are necessarily part
   // of the dense prefix.
   const ChunkData* const full_cp = first_dead_space_chunk(beg_cp, new_top_cp);
   assert(full_cp->destination() == sd.chunk_to_addr(full_cp) ||
          space->is_empty(), "no dead space allowed to the left");
   assert(full_cp->data_size() < chunk_size || full_cp == new_top_cp - 1,
          "chunk must have dead space");
   // The gc number is saved whenever a maximum compaction is done, and used to
   // determine when the maximum compaction interval has expired.  This avoids
   // successive max compactions for different reasons.
   assert(total_invocations() >= _maximum_compaction_gc_num, "sanity");
   const size_t gcs_since_max = total_invocations() - _maximum_compaction_gc_num;
   const bool interval_ended = gcs_since_max > HeapMaximumCompactionInterval ||
     total_invocations() == HeapFirstMaximumCompactionCount;
   if (maximum_compaction || full_cp == top_cp || interval_ended) {
     _maximum_compaction_gc_num = total_invocations();
     return sd.chunk_to_addr(full_cp);
   }
   const size_t space_live = pointer_delta(new_top, bottom);
   const size_t space_used = space->used_in_words();
   const size_t space_capacity = space->capacity_in_words();
   const double density = double(space_live) / double(space_capacity);
   const size_t min_percent_free =
           id == perm_space_id ? PermMarkSweepDeadRatio : MarkSweepDeadRatio;
   const double limiter = dead_wood_limiter(density, min_percent_free);
   const size_t dead_wood_max = space_used - space_live;
   const size_t dead_wood_limit = MIN2(size_t(space_capacity * limiter),
                                       dead_wood_max);
   if (TraceParallelOldGCDensePrefix) {
     tty->print_cr("space_live=" SIZE_FORMAT " " "space_used=" SIZE_FORMAT " "
                   "space_cap=" SIZE_FORMAT,
                   space_live, space_used,
                   space_capacity);
     tty->print_cr("dead_wood_limiter(%6.4f, %d)=%6.4f "
                   "dead_wood_max=" SIZE_FORMAT " dead_wood_limit=" SIZE_FORMAT,
                   density, min_percent_free, limiter,
                   dead_wood_max, dead_wood_limit);
   }
   // Locate the chunk with the desired amount of dead space to the left.
   const ChunkData* const limit_cp =
     dead_wood_limit_chunk(full_cp, top_cp, dead_wood_limit);
   // Scan from the first chunk with dead space to the limit chunk and find the
   // one with the best (largest) reclaimed ratio.
   double best_ratio = 0.0;
   const ChunkData* best_cp = full_cp;
   for (const ChunkData* cp = full_cp; cp < limit_cp; ++cp) {
     double tmp_ratio = reclaimed_ratio(cp, bottom, top, new_top);
     if (tmp_ratio > best_ratio) {
       best_cp = cp;
       best_ratio = tmp_ratio;
     }
   }
 #if     0
   // Something to consider:  if the chunk with the best ratio is 'close to' the
   // first chunk w/free space, choose the first chunk with free space
   // ("first-free").  The first-free chunk is usually near the start of the
   // heap, which means we are copying most of the heap already, so copy a bit
   // more to get complete compaction.
   if (pointer_delta(best_cp, full_cp, sizeof(ChunkData)) < 4) {
     _maximum_compaction_gc_num = total_invocations();
     best_cp = full_cp;
   }
 #endif  // #if 0
   return sd.chunk_to_addr(best_cp);
 }
 void PSParallelCompact::summarize_spaces_quick()
 {
   for (unsigned int i = 0; i < last_space_id; ++i) {
     const MutableSpace* space = _space_info[i].space();
     bool result = _summary_data.summarize(space->bottom(), space->end(),
                                           space->bottom(), space->top(),
                                           _space_info[i].new_top_addr());
     assert(result, "should never fail");
     _space_info[i].set_dense_prefix(space->bottom());
   }
 }
 void PSParallelCompact::fill_dense_prefix_end(SpaceId id)
 {
   HeapWord* const dense_prefix_end = dense_prefix(id);
   const ChunkData* chunk = _summary_data.addr_to_chunk_ptr(dense_prefix_end);
   const idx_t dense_prefix_bit = _mark_bitmap.addr_to_bit(dense_prefix_end);
   if (dead_space_crosses_boundary(chunk, dense_prefix_bit)) {
     // Only enough dead space is filled so that any remaining dead space to the
     // left is larger than the minimum filler object.  (The remainder is filled
     // during the copy/update phase.)
     //
     // The size of the dead space to the right of the boundary is not a
     // concern, since compaction will be able to use whatever space is
     // available.
     //
     // Here '||' is the boundary, 'x' represents a don't care bit and a box
     // surrounds the space to be filled with an object.
     //
     // In the 32-bit VM, each bit represents two 32-bit words:
     //                              +---+
     // a) beg_bits:  ...  x   x   x | 0 | ||   0   x  x  ...
     //    end_bits:  ...  x   x   x | 0 | ||   0   x  x  ...
     //                              +---+
     //
     // In the 64-bit VM, each bit represents one 64-bit word:
     //                              +------------+
     // b) beg_bits:  ...  x   x   x | 0   ||   0 | x  x  ...
     //    end_bits:  ...  x   x   1 | 0   ||   0 | x  x  ...
     //                              +------------+
     //                          +-------+
     // c) beg_bits:  ...  x   x | 0   0 | ||   0   x  x  ...
     //    end_bits:  ...  x   1 | 0   0 | ||   0   x  x  ...
     //                          +-------+
     //                      +-----------+
     // d) beg_bits:  ...  x | 0   0   0 | ||   0   x  x  ...
     //    end_bits:  ...  1 | 0   0   0 | ||   0   x  x  ...
     //                      +-----------+
     //                          +-------+
     // e) beg_bits:  ...  0   0 | 0   0 | ||   0   x  x  ...
     //    end_bits:  ...  0   0 | 0   0 | ||   0   x  x  ...
     //                          +-------+
     // Initially assume case a, c or e will apply.
     size_t obj_len = (size_t)oopDesc::header_size();
     HeapWord* obj_beg = dense_prefix_end - obj_len;
 #ifdef  _LP64
     if (_mark_bitmap.is_obj_end(dense_prefix_bit - 2)) {
       // Case b above.
       obj_beg = dense_prefix_end - 1;
     } else if (!_mark_bitmap.is_obj_end(dense_prefix_bit - 3) &&
                _mark_bitmap.is_obj_end(dense_prefix_bit - 4)) {
       // Case d above.
       obj_beg = dense_prefix_end - 3;
       obj_len = 3;
     }
 #endif  // #ifdef _LP64
     MemRegion region(obj_beg, obj_len);
     SharedHeap::fill_region_with_object(region);
     _mark_bitmap.mark_obj(obj_beg, obj_len);
     _summary_data.add_obj(obj_beg, obj_len);
     assert(start_array(id) != NULL, "sanity");
     start_array(id)->allocate_block(obj_beg);
   }
 }
 void
 PSParallelCompact::summarize_space(SpaceId id, bool maximum_compaction)
 {
   assert(id < last_space_id, "id out of range");
   const MutableSpace* space = _space_info[id].space();
   HeapWord** new_top_addr = _space_info[id].new_top_addr();
   HeapWord* dense_prefix_end = compute_dense_prefix(id, maximum_compaction);
   _space_info[id].set_dense_prefix(dense_prefix_end);
 #ifndef PRODUCT
   if (TraceParallelOldGCDensePrefix) {
     print_dense_prefix_stats("ratio", id, maximum_compaction, dense_prefix_end);
     HeapWord* addr = compute_dense_prefix_via_density(id, maximum_compaction);
     print_dense_prefix_stats("density", id, maximum_compaction, addr);
   }
 #endif  // #ifndef PRODUCT
   // If dead space crosses the dense prefix boundary, it is (at least partially)
   // filled with a dummy object, marked live and added to the summary data.
   // This simplifies the copy/update phase and must be done before the final
   // locations of objects are determined, to prevent leaving a fragment of dead
   // space that is too small to fill with an object.
   if (!maximum_compaction && dense_prefix_end != space->bottom()) {
     fill_dense_prefix_end(id);
   }
   // Compute the destination of each Chunk, and thus each object.
   _summary_data.summarize_dense_prefix(space->bottom(), dense_prefix_end);
   _summary_data.summarize(dense_prefix_end, space->end(),
                           dense_prefix_end, space->top(),
                           new_top_addr);
   if (TraceParallelOldGCSummaryPhase) {
     const size_t chunk_size = ParallelCompactData::ChunkSize;
     const size_t dp_chunk = _summary_data.addr_to_chunk_idx(dense_prefix_end);
     const size_t dp_words = pointer_delta(dense_prefix_end, space->bottom());
     const HeapWord* nt_aligned_up = _summary_data.chunk_align_up(*new_top_addr);
     const size_t cr_words = pointer_delta(nt_aligned_up, dense_prefix_end);
     tty->print_cr("id=%d cap=" SIZE_FORMAT " dp=" PTR_FORMAT " "
                   "dp_chunk=" SIZE_FORMAT " " "dp_count=" SIZE_FORMAT " "
                   "cr_count=" SIZE_FORMAT " " "nt=" PTR_FORMAT,
                   id, space->capacity_in_words(), dense_prefix_end,
                   dp_chunk, dp_words / chunk_size,
                   cr_words / chunk_size, *new_top_addr);
   }
 }
 void PSParallelCompact::summary_phase(ParCompactionManager* cm,
                                       bool maximum_compaction)
 {
   EventMark m("2 summarize");
   TraceTime tm("summary phase", print_phases(), true, gclog_or_tty);
   // trace("2");
 #ifdef  ASSERT
   if (VerifyParallelOldWithMarkSweep  &&
       (PSParallelCompact::total_invocations() %
          VerifyParallelOldWithMarkSweepInterval) == 0) {
     verify_mark_bitmap(_mark_bitmap);
   }
   if (TraceParallelOldGCMarkingPhase) {
     tty->print_cr("add_obj_count=" SIZE_FORMAT " "
                   "add_obj_bytes=" SIZE_FORMAT,
                   add_obj_count, add_obj_size * HeapWordSize);
     tty->print_cr("mark_bitmap_count=" SIZE_FORMAT " "
                   "mark_bitmap_bytes=" SIZE_FORMAT,
                   mark_bitmap_count, mark_bitmap_size * HeapWordSize);
   }
 #endif  // #ifdef ASSERT
   // Quick summarization of each space into itself, to see how much is live.
   summarize_spaces_quick();
   if (TraceParallelOldGCSummaryPhase) {
     tty->print_cr("summary_phase:  after summarizing each space to self");
     Universe::print();
     NOT_PRODUCT(print_chunk_ranges());
     if (Verbose) {
       NOT_PRODUCT(print_initial_summary_data(_summary_data, _space_info));
     }
   }
   // The amount of live data that will end up in old space (assuming it fits).
   size_t old_space_total_live = 0;
   unsigned int id;
   for (id = old_space_id; id < last_space_id; ++id) {
     old_space_total_live += pointer_delta(_space_info[id].new_top(),
                                           _space_info[id].space()->bottom());
   }
   const MutableSpace* old_space = _space_info[old_space_id].space();
   if (old_space_total_live > old_space->capacity_in_words()) {
     // XXX - should also try to expand
     maximum_compaction = true;
   } else if (!UseParallelOldGCDensePrefix) {
     maximum_compaction = true;
   }
   // Permanent and Old generations.
   summarize_space(perm_space_id, maximum_compaction);
   summarize_space(old_space_id, maximum_compaction);
   // Summarize the remaining spaces (those in the young gen) into old space.  If
   // the live data from a space doesn't fit, the existing summarization is left
   // intact, so the data is compacted down within the space itself.
   HeapWord** new_top_addr = _space_info[old_space_id].new_top_addr();
   HeapWord* const target_space_end = old_space->end();
   for (id = eden_space_id; id < last_space_id; ++id) {
     const MutableSpace* space = _space_info[id].space();
     const size_t live = pointer_delta(_space_info[id].new_top(),
                                       space->bottom());
     const size_t available = pointer_delta(target_space_end, *new_top_addr);
     if (live <= available) {
       // All the live data will fit.
       if (TraceParallelOldGCSummaryPhase) {
         tty->print_cr("summarizing %d into old_space @ " PTR_FORMAT,
                       id, *new_top_addr);
       }
       _summary_data.summarize(*new_top_addr, target_space_end,
                               space->bottom(), space->top(),
                               new_top_addr);
       // Reset the new_top value for the space.
       _space_info[id].set_new_top(space->bottom());
       // Clear the source_chunk field for each chunk in the space.
       ChunkData* beg_chunk = _summary_data.addr_to_chunk_ptr(space->bottom());
       ChunkData* end_chunk = _summary_data.addr_to_chunk_ptr(space->top() - 1);
       while (beg_chunk <= end_chunk) {
         beg_chunk->set_source_chunk(0);
         ++beg_chunk;
       }
     }
   }
   // Fill in the block data after any changes to the chunks have
   // been made.
 #ifdef  ASSERT
   summarize_blocks(cm, perm_space_id);
   summarize_blocks(cm, old_space_id);
 #else
   if (!UseParallelOldGCChunkPointerCalc) {
     summarize_blocks(cm, perm_space_id);
     summarize_blocks(cm, old_space_id);
   }
 #endif
   if (TraceParallelOldGCSummaryPhase) {
     tty->print_cr("summary_phase:  after final summarization");
     Universe::print();
     NOT_PRODUCT(print_chunk_ranges());
     if (Verbose) {
       NOT_PRODUCT(print_generic_summary_data(_summary_data, _space_info));
     }
   }
 }
 // Fill in the BlockData.
 // Iterate over the spaces and within each space iterate over
 // the chunks and fill in the BlockData for each chunk.
 void PSParallelCompact::summarize_blocks(ParCompactionManager* cm,
                                          SpaceId first_compaction_space_id) {
 #if     0
   DEBUG_ONLY(ParallelCompactData::BlockData::set_cur_phase(1);)
   for (SpaceId cur_space_id = first_compaction_space_id;
        cur_space_id != last_space_id;
        cur_space_id = next_compaction_space_id(cur_space_id)) {
     // Iterate over the chunks in the space
     size_t start_chunk_index =
       _summary_data.addr_to_chunk_idx(space(cur_space_id)->bottom());
     BitBlockUpdateClosure bbu(mark_bitmap(),
                               cm,
                               start_chunk_index);
     // Iterate over blocks.
     for (size_t chunk_index =  start_chunk_index;
          chunk_index < _summary_data.chunk_count() &&
          _summary_data.chunk_to_addr(chunk_index) < space(cur_space_id)->top();
          chunk_index++) {
       // Reset the closure for the new chunk.  Note that the closure
       // maintains some data that does not get reset for each chunk
       // so a new instance of the closure is no appropriate.
       bbu.reset_chunk(chunk_index);
       // Start the iteration with the first live object.  This
       // may return the end of the chunk.  That is acceptable since
       // it will properly limit the iterations.
       ParMarkBitMap::idx_t left_offset = mark_bitmap()->addr_to_bit(
         _summary_data.first_live_or_end_in_chunk(chunk_index));
       // End the iteration at the end of the chunk.
       HeapWord* chunk_addr = _summary_data.chunk_to_addr(chunk_index);
       HeapWord* chunk_end = chunk_addr + ParallelCompactData::ChunkSize;
       ParMarkBitMap::idx_t right_offset =
         mark_bitmap()->addr_to_bit(chunk_end);
       // Blocks that have not objects starting in them can be
       // skipped because their data will never be used.
       if (left_offset < right_offset) {
         // Iterate through the objects in the chunk.
         ParMarkBitMap::idx_t last_offset =
           mark_bitmap()->pair_iterate(&bbu, left_offset, right_offset);
         // If last_offset is less than right_offset, then the iterations
         // terminated while it was looking for an end bit.  "last_offset"
         // is then the offset for the last start bit.  In this situation
         // the "offset" field for the next block to the right (_cur_block + 1)
         // will not have been update although there may be live data
         // to the left of the chunk.
         size_t cur_block_plus_1 = bbu.cur_block() + 1;
         HeapWord* cur_block_plus_1_addr =
         _summary_data.block_to_addr(bbu.cur_block()) +
         ParallelCompactData::BlockSize;
         HeapWord* last_offset_addr = mark_bitmap()->bit_to_addr(last_offset);
  #if 1  // This code works.  The else doesn't but should.  Why does it?
         // The current block (cur_block()) has already been updated.
         // The last block that may need to be updated is either the
         // next block (current block + 1) or the block where the
         // last object starts (which can be greater than the
         // next block if there were no objects found in intervening
         // blocks).
         size_t last_block =
           MAX2(bbu.cur_block() + 1,
                _summary_data.addr_to_block_idx(last_offset_addr));
  #else
         // The current block has already been updated.  The only block
         // that remains to be updated is the block where the last
         // object in the chunk starts.
         size_t last_block = _summary_data.addr_to_block_idx(last_offset_addr);
  #endif
         assert_bit_is_start(last_offset);
         assert((last_block == _summary_data.block_count()) ||
              (_summary_data.block(last_block)->raw_offset() == 0),
           "Should not have been set");
         // Is the last block still in the current chunk?  If still
         // in this chunk, update the last block (the counting that
         // included the current block is meant for the offset of the last
         // block).  If not in this chunk, do nothing.  Should not
         // update a block in the next chunk.
         if (ParallelCompactData::chunk_contains_block(bbu.chunk_index(),
                                                       last_block)) {
           if (last_offset < right_offset) {
             // The last object started in this chunk but ends beyond
             // this chunk.  Update the block for this last object.
             assert(mark_bitmap()->is_marked(last_offset), "Should be marked");
             // No end bit was found.  The closure takes care of
             // the cases where
             //   an objects crosses over into the next block
             //   an objects starts and ends in the next block
             // It does not handle the case where an object is
             // the first object in a later block and extends
             // past the end of the chunk (i.e., the closure
             // only handles complete objects that are in the range
             // it is given).  That object is handed back here
             // for any special consideration necessary.
             //
             // Is the first bit in the last block a start or end bit?
             //
             // If the partial object ends in the last block L,
             // then the 1st bit in L may be an end bit.
             //
             // Else does the last object start in a block after the current
             // block? A block AA will already have been updated if an
             // object ends in the next block AA+1.  An object found to end in
             // the AA+1 is the trigger that updates AA.  Objects are being
             // counted in the current block for updaing a following
             // block.  An object may start in later block
             // block but may extend beyond the last block in the chunk.
             // Updates are only done when the end of an object has been
             // found. If the last object (covered by block L) starts
             // beyond the current block, then no object ends in L (otherwise
             // L would be the current block).  So the first bit in L is
             // a start bit.
             //
             // Else the last objects start in the current block and ends
             // beyond the chunk.  The current block has already been
             // updated and there is no later block (with an object
             // starting in it) that needs to be updated.
             //
             if (_summary_data.partial_obj_ends_in_block(last_block)) {
               _summary_data.block(last_block)->set_end_bit_offset(
                 bbu.live_data_left());
             } else if (last_offset_addr >= cur_block_plus_1_addr) {
               //   The start of the object is on a later block
               // (to the right of the current block and there are no
               // complete live objects to the left of this last object
               // within the chunk.
               //   The first bit in the block is for the start of the
               // last object.
               _summary_data.block(last_block)->set_start_bit_offset(
                 bbu.live_data_left());
             } else {
               //   The start of the last object was found in
               // the current chunk (which has already
               // been updated).
               assert(bbu.cur_block() ==
                       _summary_data.addr_to_block_idx(last_offset_addr),
                 "Should be a block already processed");
             }
 #ifdef ASSERT
             // Is there enough block information to find this object?
             // The destination of the chunk has not been set so the
             // values returned by calc_new_pointer() and
             // block_calc_new_pointer() will only be
             // offsets.  But they should agree.
             HeapWord* moved_obj_with_chunks =
               _summary_data.chunk_calc_new_pointer(last_offset_addr);
             HeapWord* moved_obj_with_blocks =
               _summary_data.calc_new_pointer(last_offset_addr);
             assert(moved_obj_with_chunks == moved_obj_with_blocks,
               "Block calculation is wrong");
 #endif
           } else if (last_block < _summary_data.block_count()) {
             // Iterations ended looking for a start bit (but
             // did not run off the end of the block table).
             _summary_data.block(last_block)->set_start_bit_offset(
               bbu.live_data_left());
           }
         }
 #ifdef ASSERT
         // Is there enough block information to find this object?
           HeapWord* left_offset_addr = mark_bitmap()->bit_to_addr(left_offset);
         HeapWord* moved_obj_with_chunks =
           _summary_data.calc_new_pointer(left_offset_addr);
         HeapWord* moved_obj_with_blocks =
           _summary_data.calc_new_pointer(left_offset_addr);
           assert(moved_obj_with_chunks == moved_obj_with_blocks,
           "Block calculation is wrong");
 #endif
         // Is there another block after the end of this chunk?
 #ifdef ASSERT
         if (last_block < _summary_data.block_count()) {
         // No object may have been found in a block.  If that
         // block is at the end of the chunk, the iteration will
         // terminate without incrementing the current block so
         // that the current block is not the last block in the
         // chunk.  That situation precludes asserting that the
         // current block is the last block in the chunk.  Assert
         // the lesser condition that the current block does not
         // exceed the chunk.
           assert(_summary_data.block_to_addr(last_block) <=
                (_summary_data.chunk_to_addr(chunk_index) +
                  ParallelCompactData::ChunkSize),
               "Chunk and block inconsistency");
           assert(last_offset <= right_offset, "Iteration over ran end");
         }
 #endif
       }
 #ifdef ASSERT
       if (PrintGCDetails && Verbose) {
         if (_summary_data.chunk(chunk_index)->partial_obj_size() == 1) {
           size_t first_block =
             chunk_index / ParallelCompactData::BlocksPerChunk;
           gclog_or_tty->print_cr("first_block " PTR_FORMAT
             " _offset " PTR_FORMAT
             "_first_is_start_bit %d",
             first_block,
             _summary_data.block(first_block)->raw_offset(),
             _summary_data.block(first_block)->first_is_start_bit());
         }
       }
 #endif
     }
   }
   DEBUG_ONLY(ParallelCompactData::BlockData::set_cur_phase(16);)
 #endif  // #if 0
 }
 // This method should contain all heap-specific policy for invoking a full
 // collection.  invoke_no_policy() will only attempt to compact the heap; it
 // will do nothing further.  If we need to bail out for policy reasons, scavenge
 // before full gc, or any other specialized behavior, it needs to be added here.
 //
 // Note that this method should only be called from the vm_thread while at a
 // safepoint.
 void PSParallelCompact::invoke(bool maximum_heap_compaction) {
   assert(SafepointSynchronize::is_at_safepoint(), "should be at safepoint");
   assert(Thread::current() == (Thread*)VMThread::vm_thread(),
          "should be in vm thread");
   ParallelScavengeHeap* heap = gc_heap();
   GCCause::Cause gc_cause = heap->gc_cause();
   assert(!heap->is_gc_active(), "not reentrant");
   PSAdaptiveSizePolicy* policy = heap->size_policy();
   // Before each allocation/collection attempt, find out from the
   // policy object if GCs are, on the whole, taking too long. If so,
   // bail out without attempting a collection.  The exceptions are
   // for explicitly requested GC's.
   if (!policy->gc_time_limit_exceeded() ||
       GCCause::is_user_requested_gc(gc_cause) ||
       GCCause::is_serviceability_requested_gc(gc_cause)) {
     IsGCActiveMark mark;
     if (ScavengeBeforeFullGC) {
       PSScavenge::invoke_no_policy();
     }
     PSParallelCompact::invoke_no_policy(maximum_heap_compaction);
   }
 }
 bool ParallelCompactData::chunk_contains(size_t chunk_index, HeapWord* addr) {
   size_t addr_chunk_index = addr_to_chunk_idx(addr);
   return chunk_index == addr_chunk_index;
 }
 bool ParallelCompactData::chunk_contains_block(size_t chunk_index,
                                                size_t block_index) {
   size_t first_block_in_chunk = chunk_index * BlocksPerChunk;
   size_t last_block_in_chunk = (chunk_index + 1) * BlocksPerChunk - 1;
   return (first_block_in_chunk <= block_index) &&
          (block_index <= last_block_in_chunk);
 }
 // This method contains no policy. You should probably
 // be calling invoke() instead.
 void PSParallelCompact::invoke_no_policy(bool maximum_heap_compaction) {
   assert(SafepointSynchronize::is_at_safepoint(), "must be at a safepoint");
   assert(ref_processor() != NULL, "Sanity");
   if (GC_locker::check_active_before_gc()) {
     return;
   }
   TimeStamp marking_start;
   TimeStamp compaction_start;
   TimeStamp collection_exit;
   ParallelScavengeHeap* heap = gc_heap();
   GCCause::Cause gc_cause = heap->gc_cause();
   PSYoungGen* young_gen = heap->young_gen();
   PSOldGen* old_gen = heap->old_gen();
   PSPermGen* perm_gen = heap->perm_gen();
   PSAdaptiveSizePolicy* size_policy = heap->size_policy();
   _print_phases = PrintGCDetails && PrintParallelOldGCPhaseTimes;
   // Make sure data structures are sane, make the heap parsable, and do other
   // miscellaneous bookkeeping.
   PreGCValues pre_gc_values;
   pre_compact(&pre_gc_values);
   // Get the compaction manager reserved for the VM thread.
   ParCompactionManager* const vmthread_cm =
     ParCompactionManager::manager_array(gc_task_manager()->workers());
   // Place after pre_compact() where the number of invocations is incremented.
   AdaptiveSizePolicyOutput(size_policy, heap->total_collections());
   {
     ResourceMark rm;
     HandleMark hm;
     const bool is_system_gc = gc_cause == GCCause::_java_lang_system_gc;
     // This is useful for debugging but don't change the output the
     // the customer sees.
     const char* gc_cause_str = "Full GC";
     if (is_system_gc && PrintGCDetails) {
       gc_cause_str = "Full GC (System)";
     }
     gclog_or_tty->date_stamp(PrintGC && PrintGCDateStamps);
     TraceCPUTime tcpu(PrintGCDetails, true, gclog_or_tty);
     TraceTime t1(gc_cause_str, PrintGC, !PrintGCDetails, gclog_or_tty);
     TraceCollectorStats tcs(counters());
     TraceMemoryManagerStats tms(true /* Full GC */);
     if (TraceGen1Time) accumulated_time()->start();
     // Let the size policy know we're starting
     size_policy->major_collection_begin();
     // When collecting the permanent generation methodOops may be moving,
     // so we either have to flush all bcp data or convert it into bci.
     CodeCache::gc_prologue();
     Threads::gc_prologue();
     NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
     COMPILER2_PRESENT(DerivedPointerTable::clear());
     ref_processor()->enable_discovery();
     bool marked_for_unloading = false;
     marking_start.update();
     marking_phase(vmthread_cm, maximum_heap_compaction);
 #ifndef PRODUCT
     if (TraceParallelOldGCMarkingPhase) {
       gclog_or_tty->print_cr("marking_phase: cas_tries %d  cas_retries %d "
         "cas_by_another %d",
         mark_bitmap()->cas_tries(), mark_bitmap()->cas_retries(),
         mark_bitmap()->cas_by_another());
     }
 #endif  // #ifndef PRODUCT
 #ifdef ASSERT
     if (VerifyParallelOldWithMarkSweep &&
         (PSParallelCompact::total_invocations() %
            VerifyParallelOldWithMarkSweepInterval) == 0) {
       gclog_or_tty->print_cr("Verify marking with mark_sweep_phase1()");
       if (PrintGCDetails && Verbose) {
         gclog_or_tty->print_cr("mark_sweep_phase1:");
       }
       // Clear the discovered lists so that discovered objects
       // don't look like they have been discovered twice.
       ref_processor()->clear_discovered_references();
       PSMarkSweep::allocate_stacks();
       MemRegion mr = Universe::heap()->reserved_region();
       PSMarkSweep::ref_processor()->enable_discovery();
       PSMarkSweep::mark_sweep_phase1(maximum_heap_compaction);
     }
 #endif
     bool max_on_system_gc = UseMaximumCompactionOnSystemGC && is_system_gc;
     summary_phase(vmthread_cm, maximum_heap_compaction || max_on_system_gc);
 #ifdef ASSERT
     if (VerifyParallelOldWithMarkSweep &&
         (PSParallelCompact::total_invocations() %
            VerifyParallelOldWithMarkSweepInterval) == 0) {
       if (PrintGCDetails && Verbose) {
         gclog_or_tty->print_cr("mark_sweep_phase2:");
       }
       PSMarkSweep::mark_sweep_phase2();
     }
 #endif
     COMPILER2_PRESENT(assert(DerivedPointerTable::is_active(), "Sanity"));
     COMPILER2_PRESENT(DerivedPointerTable::set_active(false));
     // adjust_roots() updates Universe::_intArrayKlassObj which is
     // needed by the compaction for filling holes in the dense prefix.
     adjust_roots();
 #ifdef ASSERT
     if (VerifyParallelOldWithMarkSweep &&
         (PSParallelCompact::total_invocations() %
            VerifyParallelOldWithMarkSweepInterval) == 0) {
       // Do a separate verify phase so that the verify
       // code can use the the forwarding pointers to
       // check the new pointer calculation.  The restore_marks()
       // has to be done before the real compact.
       vmthread_cm->set_action(ParCompactionManager::VerifyUpdate);
       compact_perm(vmthread_cm);
       compact_serial(vmthread_cm);
       vmthread_cm->set_action(ParCompactionManager::ResetObjects);
       compact_perm(vmthread_cm);
       compact_serial(vmthread_cm);
       vmthread_cm->set_action(ParCompactionManager::UpdateAndCopy);
       // For debugging only
       PSMarkSweep::restore_marks();
       PSMarkSweep::deallocate_stacks();
     }
 #endif
     compaction_start.update();
     // Does the perm gen always have to be done serially because
     // klasses are used in the update of an object?
     compact_perm(vmthread_cm);
     if (UseParallelOldGCCompacting) {
       compact();
     } else {
       compact_serial(vmthread_cm);
     }
     // Reset the mark bitmap, summary data, and do other bookkeeping.  Must be
     // done before resizing.
     post_compact();
     // Let the size policy know we're done
     size_policy->major_collection_end(old_gen->used_in_bytes(), gc_cause);
     if (UseAdaptiveSizePolicy) {
       if (PrintAdaptiveSizePolicy) {
         gclog_or_tty->print("AdaptiveSizeStart: ");
         gclog_or_tty->stamp();
         gclog_or_tty->print_cr(" collection: %d ",
                        heap->total_collections());
         if (Verbose) {
           gclog_or_tty->print("old_gen_capacity: %d young_gen_capacity: %d"
             " perm_gen_capacity: %d ",
             old_gen->capacity_in_bytes(), young_gen->capacity_in_bytes(),
             perm_gen->capacity_in_bytes());
         }
       }
       // Don't check if the size_policy is ready here.  Let
       // the size_policy check that internally.
       if (UseAdaptiveGenerationSizePolicyAtMajorCollection &&
           ((gc_cause != GCCause::_java_lang_system_gc) ||
             UseAdaptiveSizePolicyWithSystemGC)) {
         // Calculate optimal free space amounts
         assert(young_gen->max_size() >
           young_gen->from_space()->capacity_in_bytes() +
           young_gen->to_space()->capacity_in_bytes(),
           "Sizes of space in young gen are out-of-bounds");
         size_t max_eden_size = young_gen->max_size() -
           young_gen->from_space()->capacity_in_bytes() -
           young_gen->to_space()->capacity_in_bytes();
         size_policy->compute_generation_free_space(young_gen->used_in_bytes(),
                                  young_gen->eden_space()->used_in_bytes(),
                                  old_gen->used_in_bytes(),
                                  perm_gen->used_in_bytes(),
                                  young_gen->eden_space()->capacity_in_bytes(),
                                  old_gen->max_gen_size(),
                                  max_eden_size,
                                  true /* full gc*/,
                                  gc_cause);
         heap->resize_old_gen(size_policy->calculated_old_free_size_in_bytes());
         // Don't resize the young generation at an major collection.  A
         // desired young generation size may have been calculated but
         // resizing the young generation complicates the code because the
         // resizing of the old generation may have moved the boundary
         // between the young generation and the old generation.  Let the
         // young generation resizing happen at the minor collections.
       }
       if (PrintAdaptiveSizePolicy) {
         gclog_or_tty->print_cr("AdaptiveSizeStop: collection: %d ",
                        heap->total_collections());
       }
     }
     if (UsePerfData) {
       PSGCAdaptivePolicyCounters* const counters = heap->gc_policy_counters();
       counters->update_counters();
       counters->update_old_capacity(old_gen->capacity_in_bytes());
       counters->update_young_capacity(young_gen->capacity_in_bytes());
     }
     heap->resize_all_tlabs();
     // We collected the perm gen, so we'll resize it here.
     perm_gen->compute_new_size(pre_gc_values.perm_gen_used());
     if (TraceGen1Time) accumulated_time()->stop();
     if (PrintGC) {
       if (PrintGCDetails) {
         // No GC timestamp here.  This is after GC so it would be confusing.
         young_gen->print_used_change(pre_gc_values.young_gen_used());
         old_gen->print_used_change(pre_gc_values.old_gen_used());
         heap->print_heap_change(pre_gc_values.heap_used());
         // Print perm gen last (print_heap_change() excludes the perm gen).
         perm_gen->print_used_change(pre_gc_values.perm_gen_used());
       } else {
         heap->print_heap_change(pre_gc_values.heap_used());
       }
     }
     // Track memory usage and detect low memory
     MemoryService::track_memory_usage();
     heap->update_counters();
     if (PrintGCDetails) {
       if (size_policy->print_gc_time_limit_would_be_exceeded()) {
         if (size_policy->gc_time_limit_exceeded()) {
           gclog_or_tty->print_cr("      GC time is exceeding GCTimeLimit "
             "of %d%%", GCTimeLimit);
         } else {
           gclog_or_tty->print_cr("      GC time would exceed GCTimeLimit "
             "of %d%%", GCTimeLimit);
         }
       }
       size_policy->set_print_gc_time_limit_would_be_exceeded(false);
     }
   }
   if (VerifyAfterGC && heap->total_collections() >= VerifyGCStartAt) {
     HandleMark hm;  // Discard invalid handles created during verification
     gclog_or_tty->print(" VerifyAfterGC:");
     Universe::verify(false);
   }
   // Re-verify object start arrays
   if (VerifyObjectStartArray &&
       VerifyAfterGC) {
     old_gen->verify_object_start_array();
     perm_gen->verify_object_start_array();
   }
   NOT_PRODUCT(ref_processor()->verify_no_references_recorded());
   collection_exit.update();
   if (PrintHeapAtGC) {
     Universe::print_heap_after_gc();
   }
   if (PrintGCTaskTimeStamps) {
     gclog_or_tty->print_cr("VM-Thread " INT64_FORMAT " " INT64_FORMAT " "
                            INT64_FORMAT,
                            marking_start.ticks(), compaction_start.ticks(),
                            collection_exit.ticks());
     gc_task_manager()->print_task_time_stamps();
   }
 }
 bool PSParallelCompact::absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
                                              PSYoungGen* young_gen,
                                              PSOldGen* old_gen) {
   MutableSpace* const eden_space = young_gen->eden_space();
   assert(!eden_space->is_empty(), "eden must be non-empty");
   assert(young_gen->virtual_space()->alignment() ==
          old_gen->virtual_space()->alignment(), "alignments do not match");
   if (!(UseAdaptiveSizePolicy && UseAdaptiveGCBoundary)) {
     return false;
   }
   // Both generations must be completely committed.
   if (young_gen->virtual_space()->uncommitted_size() != 0) {
     return false;
   }
   if (old_gen->virtual_space()->uncommitted_size() != 0) {
     return false;
   }
   // Figure out how much to take from eden.  Include the average amount promoted
   // in the total; otherwise the next young gen GC will simply bail out to a
   // full GC.
   const size_t alignment = old_gen->virtual_space()->alignment();
   const size_t eden_used = eden_space->used_in_bytes();
   const size_t promoted = (size_t)size_policy->avg_promoted()->padded_average();
   const size_t absorb_size = align_size_up(eden_used + promoted, alignment);
   const size_t eden_capacity = eden_space->capacity_in_bytes();
   if (absorb_size >= eden_capacity) {
     return false; // Must leave some space in eden.
   }
   const size_t new_young_size = young_gen->capacity_in_bytes() - absorb_size;
   if (new_young_size < young_gen->min_gen_size()) {
     return false; // Respect young gen minimum size.
   }
   if (TraceAdaptiveGCBoundary && Verbose) {
     gclog_or_tty->print(" absorbing " SIZE_FORMAT "K:  "
                         "eden " SIZE_FORMAT "K->" SIZE_FORMAT "K "
                         "from " SIZE_FORMAT "K, to " SIZE_FORMAT "K "
                         "young_gen " SIZE_FORMAT "K->" SIZE_FORMAT "K ",
                         absorb_size / K,
                         eden_capacity / K, (eden_capacity - absorb_size) / K,
                         young_gen->from_space()->used_in_bytes() / K,
                         young_gen->to_space()->used_in_bytes() / K,
                         young_gen->capacity_in_bytes() / K, new_young_size / K);
   }
   // Fill the unused part of the old gen.
   MutableSpace* const old_space = old_gen->object_space();
   MemRegion old_gen_unused(old_space->top(), old_space->end());
   if (!old_gen_unused.is_empty()) {
     SharedHeap::fill_region_with_object(old_gen_unused);
   }
   // Take the live data from eden and set both top and end in the old gen to
   // eden top.  (Need to set end because reset_after_change() mangles the region
   // from end to virtual_space->high() in debug builds).
   HeapWord* const new_top = eden_space->top();
   old_gen->virtual_space()->expand_into(young_gen->virtual_space(),
                                         absorb_size);
   young_gen->reset_after_change();
   old_space->set_top(new_top);
   old_space->set_end(new_top);
   old_gen->reset_after_change();
   // Update the object start array for the filler object and the data from eden.
   ObjectStartArray* const start_array = old_gen->start_array();
   HeapWord* const start = old_gen_unused.start();
   for (HeapWord* addr = start; addr < new_top; addr += oop(addr)->size()) {
     start_array->allocate_block(addr);
   }
   // Could update the promoted average here, but it is not typically updated at
   // full GCs and the value to use is unclear.  Something like
   //
   // cur_promoted_avg + absorb_size / number_of_scavenges_since_last_full_gc.
   size_policy->set_bytes_absorbed_from_eden(absorb_size);
   return true;
 }
 GCTaskManager* const PSParallelCompact::gc_task_manager() {
   assert(ParallelScavengeHeap::gc_task_manager() != NULL,
     "shouldn't return NULL");
   return ParallelScavengeHeap::gc_task_manager();
 }
 void PSParallelCompact::marking_phase(ParCompactionManager* cm,
                                       bool maximum_heap_compaction) {
   // Recursively traverse all live objects and mark them
   EventMark m("1 mark object");
   TraceTime tm("marking phase", print_phases(), true, gclog_or_tty);
   ParallelScavengeHeap* heap = gc_heap();
   uint parallel_gc_threads = heap->gc_task_manager()->workers();
   TaskQueueSetSuper* qset = ParCompactionManager::chunk_array();
   ParallelTaskTerminator terminator(parallel_gc_threads, qset);
   PSParallelCompact::MarkAndPushClosure mark_and_push_closure(cm);
   PSParallelCompact::FollowStackClosure follow_stack_closure(cm);
   {
     TraceTime tm_m("par mark", print_phases(), true, gclog_or_tty);
     GCTaskQueue* q = GCTaskQueue::create();
     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::universe));
     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jni_handles));
     // We scan the thread roots in parallel
     Threads::create_thread_roots_marking_tasks(q);
     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::object_synchronizer));
     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::flat_profiler));
     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::management));
     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::system_dictionary));
     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::jvmti));
     q->enqueue(new MarkFromRootsTask(MarkFromRootsTask::vm_symbols));
     if (parallel_gc_threads > 1) {
       for (uint j = 0; j < parallel_gc_threads; j++) {
         q->enqueue(new StealMarkingTask(&terminator));
       }
     }
     WaitForBarrierGCTask* fin = WaitForBarrierGCTask::create();
     q->enqueue(fin);
     gc_task_manager()->add_list(q);
     fin->wait_for();
     // We have to release the barrier tasks!
     WaitForBarrierGCTask::destroy(fin);
   }
   // Process reference objects found during marking
   {
     TraceTime tm_r("reference processing", print_phases(), true, gclog_or_tty);
     ReferencePolicy *soft_ref_policy;
     if (maximum_heap_compaction) {
       soft_ref_policy = new AlwaysClearPolicy();
     } else {
 #ifdef COMPILER2
       soft_ref_policy = new LRUMaxHeapPolicy();
 #else
       soft_ref_policy = new LRUCurrentHeapPolicy();
 #endif // COMPILER2
     }
     assert(soft_ref_policy != NULL, "No soft reference policy");
     if (ref_processor()->processing_is_mt()) {
       RefProcTaskExecutor task_executor;
       ref_processor()->process_discovered_references(
         soft_ref_policy, is_alive_closure(), &mark_and_push_closure,
         &follow_stack_closure, &task_executor);
     } else {
       ref_processor()->process_discovered_references(
         soft_ref_policy, is_alive_closure(), &mark_and_push_closure,
         &follow_stack_closure, NULL);
     }
   }
   TraceTime tm_c("class unloading", print_phases(), true, gclog_or_tty);
   // Follow system dictionary roots and unload classes.
   bool purged_class = SystemDictionary::do_unloading(is_alive_closure());
   // Follow code cache roots.
   CodeCache::do_unloading(is_alive_closure(), &mark_and_push_closure,
                           purged_class);
   follow_stack(cm); // Flush marking stack.
   // Update subklass/sibling/implementor links of live klasses
   // revisit_klass_stack is used in follow_weak_klass_links().
   follow_weak_klass_links(cm);
   // Visit symbol and interned string tables and delete unmarked oops
   SymbolTable::unlink(is_alive_closure());
   StringTable::unlink(is_alive_closure());
   assert(cm->marking_stack()->size() == 0, "stack should be empty by now");
   assert(cm->overflow_stack()->is_empty(), "stack should be empty by now");
 }
 // This should be moved to the shared markSweep code!
 class PSAlwaysTrueClosure: public BoolObjectClosure {
 public:
   void do_object(oop p) { ShouldNotReachHere(); }
   bool do_object_b(oop p) { return true; }
 };
 static PSAlwaysTrueClosure always_true;
 void PSParallelCompact::adjust_roots() {
   // Adjust the pointers to reflect the new locations
   EventMark m("3 adjust roots");
   TraceTime tm("adjust roots", print_phases(), true, gclog_or_tty);
   // General strong roots.
   Universe::oops_do(adjust_root_pointer_closure());
   ReferenceProcessor::oops_do(adjust_root_pointer_closure());
   JNIHandles::oops_do(adjust_root_pointer_closure());   // Global (strong) JNI handles
   Threads::oops_do(adjust_root_pointer_closure());
   ObjectSynchronizer::oops_do(adjust_root_pointer_closure());
   FlatProfiler::oops_do(adjust_root_pointer_closure());
   Management::oops_do(adjust_root_pointer_closure());
   JvmtiExport::oops_do(adjust_root_pointer_closure());
   // SO_AllClasses
   SystemDictionary::oops_do(adjust_root_pointer_closure());
   vmSymbols::oops_do(adjust_root_pointer_closure());
   // Now adjust pointers in remaining weak roots.  (All of which should
   // have been cleared if they pointed to non-surviving objects.)
   // Global (weak) JNI handles
   JNIHandles::weak_oops_do(&always_true, adjust_root_pointer_closure());
   CodeCache::oops_do(adjust_pointer_closure());
   SymbolTable::oops_do(adjust_root_pointer_closure());
   StringTable::oops_do(adjust_root_pointer_closure());
   ref_processor()->weak_oops_do(adjust_root_pointer_closure());
   // Roots were visited so references into the young gen in roots
   // may have been scanned.  Process them also.
   // Should the reference processor have a span that excludes
   // young gen objects?
   PSScavenge::reference_processor()->weak_oops_do(
                                               adjust_root_pointer_closure());
 }
 void PSParallelCompact::compact_perm(ParCompactionManager* cm) {
   EventMark m("4 compact perm");
   TraceTime tm("compact perm gen", print_phases(), true, gclog_or_tty);
   // trace("4");
   gc_heap()->perm_gen()->start_array()->reset();
   move_and_update(cm, perm_space_id);
 }
 void PSParallelCompact::enqueue_chunk_draining_tasks(GCTaskQueue* q,
                                                      uint parallel_gc_threads) {
   TraceTime tm("drain task setup", print_phases(), true, gclog_or_tty);
   const unsigned int task_count = MAX2(parallel_gc_threads, 1U);
   for (unsigned int j = 0; j < task_count; j++) {
     q->enqueue(new DrainStacksCompactionTask());
   }
   // Find all chunks that are available (can be filled immediately) and
   // distribute them to the thread stacks.  The iteration is done in reverse
   // order (high to low) so the chunks will be removed in ascending order.
   const ParallelCompactData& sd = PSParallelCompact::summary_data();
   size_t fillable_chunks = 0;   // A count for diagnostic purposes.
   unsigned int which = 0;       // The worker thread number.
   for (unsigned int id = to_space_id; id > perm_space_id; --id) {
     SpaceInfo* const space_info = _space_info + id;
     MutableSpace* const space = space_info->space();
     HeapWord* const new_top = space_info->new_top();
     const size_t beg_chunk = sd.addr_to_chunk_idx(space_info->dense_prefix());
     const size_t end_chunk = sd.addr_to_chunk_idx(sd.chunk_align_up(new_top));
     assert(end_chunk > 0, "perm gen cannot be empty");
     for (size_t cur = end_chunk - 1; cur >= beg_chunk; --cur) {
       if (sd.chunk(cur)->claim_unsafe()) {
         ParCompactionManager* cm = ParCompactionManager::manager_array(which);
         cm->save_for_processing(cur);
         if (TraceParallelOldGCCompactionPhase && Verbose) {
           const size_t count_mod_8 = fillable_chunks & 7;
           if (count_mod_8 == 0) gclog_or_tty->print("fillable: ");
           gclog_or_tty->print(" " SIZE_FORMAT_W("7"), cur);
           if (count_mod_8 == 7) gclog_or_tty->cr();
         }
         NOT_PRODUCT(++fillable_chunks;)
         // Assign chunks to threads in round-robin fashion.
         if (++which == task_count) {
           which = 0;
         }
       }
     }
   }
   if (TraceParallelOldGCCompactionPhase) {
     if (Verbose && (fillable_chunks & 7) != 0) gclog_or_tty->cr();
     gclog_or_tty->print_cr("%u initially fillable chunks", fillable_chunks);
   }
 }
 #define PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING 4
 void PSParallelCompact::enqueue_dense_prefix_tasks(GCTaskQueue* q,
                                                     uint parallel_gc_threads) {
   TraceTime tm("dense prefix task setup", print_phases(), true, gclog_or_tty);
   ParallelCompactData& sd = PSParallelCompact::summary_data();
   // Iterate over all the spaces adding tasks for updating
   // chunks in the dense prefix.  Assume that 1 gc thread
   // will work on opening the gaps and the remaining gc threads
   // will work on the dense prefix.
   SpaceId space_id = old_space_id;
   while (space_id != last_space_id) {
     HeapWord* const dense_prefix_end = _space_info[space_id].dense_prefix();
     const MutableSpace* const space = _space_info[space_id].space();
     if (dense_prefix_end == space->bottom()) {
       // There is no dense prefix for this space.
       space_id = next_compaction_space_id(space_id);
       continue;
     }
     // The dense prefix is before this chunk.
     size_t chunk_index_end_dense_prefix =
         sd.addr_to_chunk_idx(dense_prefix_end);
     ChunkData* const dense_prefix_cp = sd.chunk(chunk_index_end_dense_prefix);
     assert(dense_prefix_end == space->end() ||
            dense_prefix_cp->available() ||
            dense_prefix_cp->claimed(),
            "The chunk after the dense prefix should always be ready to fill");
     size_t chunk_index_start = sd.addr_to_chunk_idx(space->bottom());
     // Is there dense prefix work?
     size_t total_dense_prefix_chunks =
       chunk_index_end_dense_prefix - chunk_index_start;
     // How many chunks of the dense prefix should be given to
     // each thread?
     if (total_dense_prefix_chunks > 0) {
       uint tasks_for_dense_prefix = 1;
       if (UseParallelDensePrefixUpdate) {
         if (total_dense_prefix_chunks <=
             (parallel_gc_threads * PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING)) {
           // Don't over partition.  This assumes that
           // PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING is a small integer value
           // so there are not many chunks to process.
           tasks_for_dense_prefix = parallel_gc_threads;
         } else {
           // Over partition
           tasks_for_dense_prefix = parallel_gc_threads *
             PAR_OLD_DENSE_PREFIX_OVER_PARTITIONING;
         }
       }
       size_t chunks_per_thread = total_dense_prefix_chunks /
         tasks_for_dense_prefix;
       // Give each thread at least 1 chunk.
       if (chunks_per_thread == 0) {
         chunks_per_thread = 1;
       }
       for (uint k = 0; k < tasks_for_dense_prefix; k++) {
         if (chunk_index_start >= chunk_index_end_dense_prefix) {
           break;
         }
         // chunk_index_end is not processed
         size_t chunk_index_end = MIN2(chunk_index_start + chunks_per_thread,
                                       chunk_index_end_dense_prefix);
         q->enqueue(new UpdateDensePrefixTask(
                                  space_id,
                                  chunk_index_start,
                                  chunk_index_end));
         chunk_index_start = chunk_index_end;
       }
     }
     // This gets any part of the dense prefix that did not
     // fit evenly.
     if (chunk_index_start < chunk_index_end_dense_prefix) {
       q->enqueue(new UpdateDensePrefixTask(
                                  space_id,
                                  chunk_index_start,
                                  chunk_index_end_dense_prefix));
     }
     space_id = next_compaction_space_id(space_id);
   }  // End tasks for dense prefix
 }
 void PSParallelCompact::enqueue_chunk_stealing_tasks(
                                      GCTaskQueue* q,
                                      ParallelTaskTerminator* terminator_ptr,
                                      uint parallel_gc_threads) {
   TraceTime tm("steal task setup", print_phases(), true, gclog_or_tty);
   // Once a thread has drained it's stack, it should try to steal chunks from
   // other threads.
   if (parallel_gc_threads > 1) {
     for (uint j = 0; j < parallel_gc_threads; j++) {
       q->enqueue(new StealChunkCompactionTask(terminator_ptr));
     }
   }
 }
 void PSParallelCompact::compact() {
   EventMark m("5 compact");
   // trace("5");
   TraceTime tm("compaction phase", print_phases(), true, gclog_or_tty);
   ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
   assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
   PSOldGen* old_gen = heap->old_gen();
   old_gen->start_array()->reset();
   uint parallel_gc_threads = heap->gc_task_manager()->workers();
   TaskQueueSetSuper* qset = ParCompactionManager::chunk_array();
   ParallelTaskTerminator terminator(parallel_gc_threads, qset);
   GCTaskQueue* q = GCTaskQueue::create();
   enqueue_chunk_draining_tasks(q, parallel_gc_threads);
   enqueue_dense_prefix_tasks(q, parallel_gc_threads);
   enqueue_chunk_stealing_tasks(q, &terminator, parallel_gc_threads);
   {
     TraceTime tm_pc("par compact", print_phases(), true, gclog_or_tty);
     WaitForBarrierGCTask* fin = WaitForBarrierGCTask::create();
     q->enqueue(fin);
     gc_task_manager()->add_list(q);
     fin->wait_for();
     // We have to release the barrier tasks!
     WaitForBarrierGCTask::destroy(fin);
 #ifdef  ASSERT
     // Verify that all chunks have been processed before the deferred updates.
     // Note that perm_space_id is skipped; this type of verification is not
     // valid until the perm gen is compacted by chunks.
     for (unsigned int id = old_space_id; id < last_space_id; ++id) {
       verify_complete(SpaceId(id));
     }
 #endif
   }
   {
     // Update the deferred objects, if any.  Any compaction manager can be used.
     TraceTime tm_du("deferred updates", print_phases(), true, gclog_or_tty);
     ParCompactionManager* cm = ParCompactionManager::manager_array(0);
     for (unsigned int id = old_space_id; id < last_space_id; ++id) {
       update_deferred_objects(cm, SpaceId(id));
     }
   }
 }
 #ifdef  ASSERT
 void PSParallelCompact::verify_complete(SpaceId space_id) {
   // All Chunks between space bottom() to new_top() should be marked as filled
   // and all Chunks between new_top() and top() should be available (i.e.,
   // should have been emptied).
   ParallelCompactData& sd = summary_data();
   SpaceInfo si = _space_info[space_id];
   HeapWord* new_top_addr = sd.chunk_align_up(si.new_top());
   HeapWord* old_top_addr = sd.chunk_align_up(si.space()->top());
   const size_t beg_chunk = sd.addr_to_chunk_idx(si.space()->bottom());
   const size_t new_top_chunk = sd.addr_to_chunk_idx(new_top_addr);
   const size_t old_top_chunk = sd.addr_to_chunk_idx(old_top_addr);
   bool issued_a_warning = false;
   size_t cur_chunk;
   for (cur_chunk = beg_chunk; cur_chunk < new_top_chunk; ++cur_chunk) {
     const ChunkData* const c = sd.chunk(cur_chunk);
     if (!c->completed()) {
       warning("chunk " SIZE_FORMAT " not filled:  "
               "destination_count=" SIZE_FORMAT,
               cur_chunk, c->destination_count());
       issued_a_warning = true;
     }
   }
   for (cur_chunk = new_top_chunk; cur_chunk < old_top_chunk; ++cur_chunk) {
     const ChunkData* const c = sd.chunk(cur_chunk);
     if (!c->available()) {
       warning("chunk " SIZE_FORMAT " not empty:   "
               "destination_count=" SIZE_FORMAT,
               cur_chunk, c->destination_count());
       issued_a_warning = true;
     }
   }
   if (issued_a_warning) {
     print_chunk_ranges();
   }
 }
 #endif  // #ifdef ASSERT
 void PSParallelCompact::compact_serial(ParCompactionManager* cm) {
   EventMark m("5 compact serial");
   TraceTime tm("compact serial", print_phases(), true, gclog_or_tty);
   ParallelScavengeHeap* heap = (ParallelScavengeHeap*)Universe::heap();
   assert(heap->kind() == CollectedHeap::ParallelScavengeHeap, "Sanity");
   PSYoungGen* young_gen = heap->young_gen();
   PSOldGen* old_gen = heap->old_gen();
   old_gen->start_array()->reset();
   old_gen->move_and_update(cm);
   young_gen->move_and_update(cm);
 }
 void PSParallelCompact::follow_stack(ParCompactionManager* cm) {
   while(!cm->overflow_stack()->is_empty()) {
     oop obj = cm->overflow_stack()->pop();
     obj->follow_contents(cm);
   }
   oop obj;
   // obj is a reference!!!
   while (cm->marking_stack()->pop_local(obj)) {
     // It would be nice to assert about the type of objects we might
     // pop, but they can come from anywhere, unfortunately.
     obj->follow_contents(cm);
   }
 }
 void
 PSParallelCompact::follow_weak_klass_links(ParCompactionManager* serial_cm) {
   // All klasses on the revisit stack are marked at this point.
   // Update and follow all subklass, sibling and implementor links.
   for (uint i = 0; i < ParallelGCThreads+1; i++) {
     ParCompactionManager* cm = ParCompactionManager::manager_array(i);
     KeepAliveClosure keep_alive_closure(cm);
     for (int i = 0; i < cm->revisit_klass_stack()->length(); i++) {
       cm->revisit_klass_stack()->at(i)->follow_weak_klass_links(
         is_alive_closure(),
         &keep_alive_closure);
     }
     follow_stack(cm);
   }
 }
 void
 PSParallelCompact::revisit_weak_klass_link(ParCompactionManager* cm, Klass* k) {
   cm->revisit_klass_stack()->push(k);
 }
 #ifdef VALIDATE_MARK_SWEEP
 void PSParallelCompact::track_adjusted_pointer(void* p, bool isroot) {
   if (!ValidateMarkSweep)
     return;
   if (!isroot) {
     if (_pointer_tracking) {
       guarantee(_adjusted_pointers->contains(p), "should have seen this pointer");
       _adjusted_pointers->remove(p);
     }
   } else {
     ptrdiff_t index = _root_refs_stack->find(p);
     if (index != -1) {
       int l = _root_refs_stack->length();
       if (l > 0 && l - 1 != index) {
         void* last = _root_refs_stack->pop();
         assert(last != p, "should be different");
         _root_refs_stack->at_put(index, last);
       } else {
         _root_refs_stack->remove(p);
       }
     }
   }
 }
 void PSParallelCompact::check_adjust_pointer(void* p) {
   _adjusted_pointers->push(p);
 }
 class AdjusterTracker: public OopClosure {
  public:
   AdjusterTracker() {};
   void do_oop(oop* o)         { PSParallelCompact::check_adjust_pointer(o); }
   void do_oop(narrowOop* o)   { PSParallelCompact::check_adjust_pointer(o); }
 };
 void PSParallelCompact::track_interior_pointers(oop obj) {
   if (ValidateMarkSweep) {
     _adjusted_pointers->clear();
     _pointer_tracking = true;
     AdjusterTracker checker;
     obj->oop_iterate(&checker);
   }
 }
 void PSParallelCompact::check_interior_pointers() {
   if (ValidateMarkSweep) {
     _pointer_tracking = false;
     guarantee(_adjusted_pointers->length() == 0, "should have processed the same pointers");
   }
 }
 void PSParallelCompact::reset_live_oop_tracking(bool at_perm) {
   if (ValidateMarkSweep) {
     guarantee((size_t)_live_oops->length() == _live_oops_index, "should be at end of live oops");
     _live_oops_index = at_perm ? _live_oops_index_at_perm : 0;
   }
 }
 void PSParallelCompact::register_live_oop(oop p, size_t size) {
   if (ValidateMarkSweep) {
     _live_oops->push(p);
     _live_oops_size->push(size);
     _live_oops_index++;
   }
 }
 void PSParallelCompact::validate_live_oop(oop p, size_t size) {
   if (ValidateMarkSweep) {
     oop obj = _live_oops->at((int)_live_oops_index);
     guarantee(obj == p, "should be the same object");
     guarantee(_live_oops_size->at((int)_live_oops_index) == size, "should be the same size");
     _live_oops_index++;
   }
 }
 void PSParallelCompact::live_oop_moved_to(HeapWord* q, size_t size,
                                   HeapWord* compaction_top) {
   assert(oop(q)->forwardee() == NULL || oop(q)->forwardee() == oop(compaction_top),
          "should be moved to forwarded location");
   if (ValidateMarkSweep) {
     PSParallelCompact::validate_live_oop(oop(q), size);
     _live_oops_moved_to->push(oop(compaction_top));
   }
   if (RecordMarkSweepCompaction) {
     _cur_gc_live_oops->push(q);
     _cur_gc_live_oops_moved_to->push(compaction_top);
     _cur_gc_live_oops_size->push(size);
   }
 }
 void PSParallelCompact::compaction_complete() {
   if (RecordMarkSweepCompaction) {
     GrowableArray<HeapWord*>* _tmp_live_oops          = _cur_gc_live_oops;
     GrowableArray<HeapWord*>* _tmp_live_oops_moved_to = _cur_gc_live_oops_moved_to;
     GrowableArray<size_t>   * _tmp_live_oops_size     = _cur_gc_live_oops_size;
     _cur_gc_live_oops           = _last_gc_live_oops;
     _cur_gc_live_oops_moved_to  = _last_gc_live_oops_moved_to;
     _cur_gc_live_oops_size      = _last_gc_live_oops_size;
     _last_gc_live_oops          = _tmp_live_oops;
     _last_gc_live_oops_moved_to = _tmp_live_oops_moved_to;
     _last_gc_live_oops_size     = _tmp_live_oops_size;
   }
 }
 void PSParallelCompact::print_new_location_of_heap_address(HeapWord* q) {
   if (!RecordMarkSweepCompaction) {
     tty->print_cr("Requires RecordMarkSweepCompaction to be enabled");
     return;
   }
   if (_last_gc_live_oops == NULL) {
     tty->print_cr("No compaction information gathered yet");
     return;
   }
   for (int i = 0; i < _last_gc_live_oops->length(); i++) {
     HeapWord* old_oop = _last_gc_live_oops->at(i);
     size_t    sz      = _last_gc_live_oops_size->at(i);
     if (old_oop <= q && q < (old_oop + sz)) {
       HeapWord* new_oop = _last_gc_live_oops_moved_to->at(i);
       size_t offset = (q - old_oop);
       tty->print_cr("Address " PTR_FORMAT, q);
       tty->print_cr(" Was in oop " PTR_FORMAT ", size %d, at offset %d", old_oop, sz, offset);
       tty->print_cr(" Now in oop " PTR_FORMAT ", actual address " PTR_FORMAT, new_oop, new_oop + offset);
       return;
     }
   }
   tty->print_cr("Address " PTR_FORMAT " not found in live oop information from last GC", q);
 }
 #endif //VALIDATE_MARK_SWEEP
 // Update interior oops in the ranges of chunks [beg_chunk, end_chunk).
 void
 PSParallelCompact::update_and_deadwood_in_dense_prefix(ParCompactionManager* cm,
                                                        SpaceId space_id,
                                                        size_t beg_chunk,
                                                        size_t end_chunk) {
   ParallelCompactData& sd = summary_data();
   ParMarkBitMap* const mbm = mark_bitmap();
   HeapWord* beg_addr = sd.chunk_to_addr(beg_chunk);
   HeapWord* const end_addr = sd.chunk_to_addr(end_chunk);
   assert(beg_chunk <= end_chunk, "bad chunk range");
   assert(end_addr <= dense_prefix(space_id), "not in the dense prefix");
 #ifdef  ASSERT
   // Claim the chunks to avoid triggering an assert when they are marked as
   // filled.
   for (size_t claim_chunk = beg_chunk; claim_chunk < end_chunk; ++claim_chunk) {
     assert(sd.chunk(claim_chunk)->claim_unsafe(), "claim() failed");
   }
 #endif  // #ifdef ASSERT
   if (beg_addr != space(space_id)->bottom()) {
     // Find the first live object or block of dead space that *starts* in this
     // range of chunks.  If a partial object crosses onto the chunk, skip it; it
     // will be marked for 'deferred update' when the object head is processed.
     // If dead space crosses onto the chunk, it is also skipped; it will be
     // filled when the prior chunk is processed.  If neither of those apply, the
     // first word in the chunk is the start of a live object or dead space.
     assert(beg_addr > space(space_id)->bottom(), "sanity");
     const ChunkData* const cp = sd.chunk(beg_chunk);
     if (cp->partial_obj_size() != 0) {
       beg_addr = sd.partial_obj_end(beg_chunk);
     } else if (dead_space_crosses_boundary(cp, mbm->addr_to_bit(beg_addr))) {
       beg_addr = mbm->find_obj_beg(beg_addr, end_addr);
     }
   }
   if (beg_addr < end_addr) {
     // A live object or block of dead space starts in this range of Chunks.
      HeapWord* const dense_prefix_end = dense_prefix(space_id);
     // Create closures and iterate.
     UpdateOnlyClosure update_closure(mbm, cm, space_id);
     FillClosure fill_closure(cm, space_id);
     ParMarkBitMap::IterationStatus status;
     status = mbm->iterate(&update_closure, &fill_closure, beg_addr, end_addr,
                           dense_prefix_end);
     if (status == ParMarkBitMap::incomplete) {
       update_closure.do_addr(update_closure.source());
     }
   }
   // Mark the chunks as filled.
   ChunkData* const beg_cp = sd.chunk(beg_chunk);
   ChunkData* const end_cp = sd.chunk(end_chunk);
   for (ChunkData* cp = beg_cp; cp < end_cp; ++cp) {
     cp->set_completed();
   }
 }
 // Return the SpaceId for the space containing addr.  If addr is not in the
 // heap, last_space_id is returned.  In debug mode it expects the address to be
 // in the heap and asserts such.
 PSParallelCompact::SpaceId PSParallelCompact::space_id(HeapWord* addr) {
   assert(Universe::heap()->is_in_reserved(addr), "addr not in the heap");
   for (unsigned int id = perm_space_id; id < last_space_id; ++id) {
     if (_space_info[id].space()->contains(addr)) {
       return SpaceId(id);
     }
   }
   assert(false, "no space contains the addr");
   return last_space_id;
 }
 void PSParallelCompact::update_deferred_objects(ParCompactionManager* cm,
                                                 SpaceId id) {
   assert(id < last_space_id, "bad space id");
   ParallelCompactData& sd = summary_data();
   const SpaceInfo* const space_info = _space_info + id;
   ObjectStartArray* const start_array = space_info->start_array();
   const MutableSpace* const space = space_info->space();
   assert(space_info->dense_prefix() >= space->bottom(), "dense_prefix not set");
   HeapWord* const beg_addr = space_info->dense_prefix();
   HeapWord* const end_addr = sd.chunk_align_up(space_info->new_top());
   const ChunkData* const beg_chunk = sd.addr_to_chunk_ptr(beg_addr);
   const ChunkData* const end_chunk = sd.addr_to_chunk_ptr(end_addr);
   const ChunkData* cur_chunk;
   for (cur_chunk = beg_chunk; cur_chunk < end_chunk; ++cur_chunk) {
     HeapWord* const addr = cur_chunk->deferred_obj_addr();
     if (addr != NULL) {
       if (start_array != NULL) {
         start_array->allocate_block(addr);
       }
       oop(addr)->update_contents(cm);
       assert(oop(addr)->is_oop_or_null(), "should be an oop now");
     }
   }
 }
 // Skip over count live words starting from beg, and return the address of the
 // next live word.  Unless marked, the word corresponding to beg is assumed to
 // be dead.  Callers must either ensure beg does not correspond to the middle of
 // an object, or account for those live words in some other way.  Callers must
 // also ensure that there are enough live words in the range [beg, end) to skip.
 HeapWord*
 PSParallelCompact::skip_live_words(HeapWord* beg, HeapWord* end, size_t count)
 {
   assert(count > 0, "sanity");
   ParMarkBitMap* m = mark_bitmap();
   idx_t bits_to_skip = m->words_to_bits(count);
   idx_t cur_beg = m->addr_to_bit(beg);
   const idx_t search_end = BitMap::word_align_up(m->addr_to_bit(end));
   do {
     cur_beg = m->find_obj_beg(cur_beg, search_end);
     idx_t cur_end = m->find_obj_end(cur_beg, search_end);
     const size_t obj_bits = cur_end - cur_beg + 1;
     if (obj_bits > bits_to_skip) {
       return m->bit_to_addr(cur_beg + bits_to_skip);
     }
     bits_to_skip -= obj_bits;
     cur_beg = cur_end + 1;
   } while (bits_to_skip > 0);
   // Skipping the desired number of words landed just past the end of an object.
   // Find the start of the next object.
   cur_beg = m->find_obj_beg(cur_beg, search_end);
   assert(cur_beg < m->addr_to_bit(end), "not enough live words to skip");
   return m->bit_to_addr(cur_beg);
 }
 HeapWord*
 PSParallelCompact::first_src_addr(HeapWord* const dest_addr,
                                  size_t src_chunk_idx)
 {
   ParMarkBitMap* const bitmap = mark_bitmap();
   const ParallelCompactData& sd = summary_data();
   const size_t ChunkSize = ParallelCompactData::ChunkSize;
   assert(sd.is_chunk_aligned(dest_addr), "not aligned");
   const ChunkData* const src_chunk_ptr = sd.chunk(src_chunk_idx);
   const size_t partial_obj_size = src_chunk_ptr->partial_obj_size();
   HeapWord* const src_chunk_destination = src_chunk_ptr->destination();
   assert(dest_addr >= src_chunk_destination, "wrong src chunk");
   assert(src_chunk_ptr->data_size() > 0, "src chunk cannot be empty");
   HeapWord* const src_chunk_beg = sd.chunk_to_addr(src_chunk_idx);
   HeapWord* const src_chunk_end = src_chunk_beg + ChunkSize;
   HeapWord* addr = src_chunk_beg;
   if (dest_addr == src_chunk_destination) {
     // Return the first live word in the source chunk.
     if (partial_obj_size == 0) {
       addr = bitmap->find_obj_beg(addr, src_chunk_end);
       assert(addr < src_chunk_end, "no objects start in src chunk");
     }
     return addr;
   }
   // Must skip some live data.
   size_t words_to_skip = dest_addr - src_chunk_destination;
   assert(src_chunk_ptr->data_size() > words_to_skip, "wrong src chunk");
   if (partial_obj_size >= words_to_skip) {
     // All the live words to skip are part of the partial object.
     addr += words_to_skip;
     if (partial_obj_size == words_to_skip) {
       // Find the first live word past the partial object.
       addr = bitmap->find_obj_beg(addr, src_chunk_end);
       assert(addr < src_chunk_end, "wrong src chunk");
     }
     return addr;
   }
   // Skip over the partial object (if any).
   if (partial_obj_size != 0) {
     words_to_skip -= partial_obj_size;
     addr += partial_obj_size;
   }
   // Skip over live words due to objects that start in the chunk.
   addr = skip_live_words(addr, src_chunk_end, words_to_skip);
   assert(addr < src_chunk_end, "wrong src chunk");
   return addr;
 }
 void PSParallelCompact::decrement_destination_counts(ParCompactionManager* cm,
                                                      size_t beg_chunk,
                                                      HeapWord* end_addr)
 {
   ParallelCompactData& sd = summary_data();
   ChunkData* const beg = sd.chunk(beg_chunk);
   HeapWord* const end_addr_aligned_up = sd.chunk_align_up(end_addr);
   ChunkData* const end = sd.addr_to_chunk_ptr(end_addr_aligned_up);
   size_t cur_idx = beg_chunk;
   for (ChunkData* cur = beg; cur < end; ++cur, ++cur_idx) {
     assert(cur->data_size() > 0, "chunk must have live data");
     cur->decrement_destination_count();
     if (cur_idx <= cur->source_chunk() && cur->available() && cur->claim()) {
       cm->save_for_processing(cur_idx);
     }
   }
 }
 size_t PSParallelCompact::next_src_chunk(MoveAndUpdateClosure& closure,
                                          SpaceId& src_space_id,
                                          HeapWord*& src_space_top,
                                          HeapWord* end_addr)
 {
   typedef ParallelCompactData::ChunkData ChunkData;
   ParallelCompactData& sd = PSParallelCompact::summary_data();
   const size_t chunk_size = ParallelCompactData::ChunkSize;
   size_t src_chunk_idx = 0;
   // Skip empty chunks (if any) up to the top of the space.
   HeapWord* const src_aligned_up = sd.chunk_align_up(end_addr);
   ChunkData* src_chunk_ptr = sd.addr_to_chunk_ptr(src_aligned_up);
   HeapWord* const top_aligned_up = sd.chunk_align_up(src_space_top);
   const ChunkData* const top_chunk_ptr = sd.addr_to_chunk_ptr(top_aligned_up);
   while (src_chunk_ptr < top_chunk_ptr && src_chunk_ptr->data_size() == 0) {
     ++src_chunk_ptr;
   }
   if (src_chunk_ptr < top_chunk_ptr) {
     // The next source chunk is in the current space.  Update src_chunk_idx and
     // the source address to match src_chunk_ptr.
     src_chunk_idx = sd.chunk(src_chunk_ptr);
     HeapWord* const src_chunk_addr = sd.chunk_to_addr(src_chunk_idx);
     if (src_chunk_addr > closure.source()) {
       closure.set_source(src_chunk_addr);
     }
     return src_chunk_idx;
   }
   // Switch to a new source space and find the first non-empty chunk.
   unsigned int space_id = src_space_id + 1;
   assert(space_id < last_space_id, "not enough spaces");
   HeapWord* const destination = closure.destination();
   do {
     MutableSpace* space = _space_info[space_id].space();
     HeapWord* const bottom = space->bottom();
     const ChunkData* const bottom_cp = sd.addr_to_chunk_ptr(bottom);
     // Iterate over the spaces that do not compact into themselves.
     if (bottom_cp->destination() != bottom) {
       HeapWord* const top_aligned_up = sd.chunk_align_up(space->top());
       const ChunkData* const top_cp = sd.addr_to_chunk_ptr(top_aligned_up);
       for (const ChunkData* src_cp = bottom_cp; src_cp < top_cp; ++src_cp) {
         if (src_cp->live_obj_size() > 0) {
           // Found it.
           assert(src_cp->destination() == destination,
                  "first live obj in the space must match the destination");
           assert(src_cp->partial_obj_size() == 0,
                  "a space cannot begin with a partial obj");
           src_space_id = SpaceId(space_id);
           src_space_top = space->top();
           const size_t src_chunk_idx = sd.chunk(src_cp);
           closure.set_source(sd.chunk_to_addr(src_chunk_idx));
           return src_chunk_idx;
         } else {
           assert(src_cp->data_size() == 0, "sanity");
         }
       }
     }
   } while (++space_id < last_space_id);
   assert(false, "no source chunk was found");
   return 0;
 }
 void PSParallelCompact::fill_chunk(ParCompactionManager* cm, size_t chunk_idx)
 {
   typedef ParMarkBitMap::IterationStatus IterationStatus;
   const size_t ChunkSize = ParallelCompactData::ChunkSize;
   ParMarkBitMap* const bitmap = mark_bitmap();
   ParallelCompactData& sd = summary_data();
   ChunkData* const chunk_ptr = sd.chunk(chunk_idx);
   // Get the items needed to construct the closure.
   HeapWord* dest_addr = sd.chunk_to_addr(chunk_idx);
   SpaceId dest_space_id = space_id(dest_addr);
   ObjectStartArray* start_array = _space_info[dest_space_id].start_array();
   HeapWord* new_top = _space_info[dest_space_id].new_top();
   assert(dest_addr < new_top, "sanity");
   const size_t words = MIN2(pointer_delta(new_top, dest_addr), ChunkSize);
   // Get the source chunk and related info.
   size_t src_chunk_idx = chunk_ptr->source_chunk();
   SpaceId src_space_id = space_id(sd.chunk_to_addr(src_chunk_idx));
   HeapWord* src_space_top = _space_info[src_space_id].space()->top();
   MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words);
   closure.set_source(first_src_addr(dest_addr, src_chunk_idx));
   // Adjust src_chunk_idx to prepare for decrementing destination counts (the
   // destination count is not decremented when a chunk is copied to itself).
   if (src_chunk_idx == chunk_idx) {
     src_chunk_idx += 1;
   }
   if (bitmap->is_unmarked(closure.source())) {
     // The first source word is in the middle of an object; copy the remainder
     // of the object or as much as will fit.  The fact that pointer updates were
     // deferred will be noted when the object header is processed.
     HeapWord* const old_src_addr = closure.source();
     closure.copy_partial_obj();
     if (closure.is_full()) {
       decrement_destination_counts(cm, src_chunk_idx, closure.source());
       chunk_ptr->set_deferred_obj_addr(NULL);
       chunk_ptr->set_completed();
       return;
     }
     HeapWord* const end_addr = sd.chunk_align_down(closure.source());
     if (sd.chunk_align_down(old_src_addr) != end_addr) {
       // The partial object was copied from more than one source chunk.
       decrement_destination_counts(cm, src_chunk_idx, end_addr);
       // Move to the next source chunk, possibly switching spaces as well.  All
       // args except end_addr may be modified.
       src_chunk_idx = next_src_chunk(closure, src_space_id, src_space_top,
                                      end_addr);
     }
   }
   do {
     HeapWord* const cur_addr = closure.source();
     HeapWord* const end_addr = MIN2(sd.chunk_align_up(cur_addr + 1),
                                     src_space_top);
     IterationStatus status = bitmap->iterate(&closure, cur_addr, end_addr);
     if (status == ParMarkBitMap::incomplete) {
       // The last obj that starts in the source chunk does not end in the chunk.
       assert(closure.source() < end_addr, "sanity")
       HeapWord* const obj_beg = closure.source();
       HeapWord* const range_end = MIN2(obj_beg + closure.words_remaining(),
                                        src_space_top);
       HeapWord* const obj_end = bitmap->find_obj_end(obj_beg, range_end);
       if (obj_end < range_end) {
         // The end was found; the entire object will fit.
         status = closure.do_addr(obj_beg, bitmap->obj_size(obj_beg, obj_end));
         assert(status != ParMarkBitMap::would_overflow, "sanity");
       } else {
         // The end was not found; the object will not fit.
         assert(range_end < src_space_top, "obj cannot cross space boundary");
         status = ParMarkBitMap::would_overflow;
       }
     }
     if (status == ParMarkBitMap::would_overflow) {
       // The last object did not fit.  Note that interior oop updates were
       // deferred, then copy enough of the object to fill the chunk.
       chunk_ptr->set_deferred_obj_addr(closure.destination());
       status = closure.copy_until_full(); // copies from closure.source()
       decrement_destination_counts(cm, src_chunk_idx, closure.source());
       chunk_ptr->set_completed();
       return;
     }
     if (status == ParMarkBitMap::full) {
       decrement_destination_counts(cm, src_chunk_idx, closure.source());
       chunk_ptr->set_deferred_obj_addr(NULL);
       chunk_ptr->set_completed();
       return;
     }
     decrement_destination_counts(cm, src_chunk_idx, end_addr);
     // Move to the next source chunk, possibly switching spaces as well.  All
     // args except end_addr may be modified.
     src_chunk_idx = next_src_chunk(closure, src_space_id, src_space_top,
                                    end_addr);
   } while (true);
 }
 void
 PSParallelCompact::move_and_update(ParCompactionManager* cm, SpaceId space_id) {
   const MutableSpace* sp = space(space_id);
   if (sp->is_empty()) {
     return;
   }
   ParallelCompactData& sd = PSParallelCompact::summary_data();
   ParMarkBitMap* const bitmap = mark_bitmap();
   HeapWord* const dp_addr = dense_prefix(space_id);
   HeapWord* beg_addr = sp->bottom();
   HeapWord* end_addr = sp->top();
 #ifdef ASSERT
   assert(beg_addr <= dp_addr && dp_addr <= end_addr, "bad dense prefix");
   if (cm->should_verify_only()) {
     VerifyUpdateClosure verify_update(cm, sp);
     bitmap->iterate(&verify_update, beg_addr, end_addr);
     return;
   }
   if (cm->should_reset_only()) {
     ResetObjectsClosure reset_objects(cm);
     bitmap->iterate(&reset_objects, beg_addr, end_addr);
     return;
   }
 #endif
   const size_t beg_chunk = sd.addr_to_chunk_idx(beg_addr);
   const size_t dp_chunk = sd.addr_to_chunk_idx(dp_addr);
   if (beg_chunk < dp_chunk) {
     update_and_deadwood_in_dense_prefix(cm, space_id, beg_chunk, dp_chunk);
   }
   // The destination of the first live object that starts in the chunk is one
   // past the end of the partial object entering the chunk (if any).
   HeapWord* const dest_addr = sd.partial_obj_end(dp_chunk);
   HeapWord* const new_top = _space_info[space_id].new_top();
   assert(new_top >= dest_addr, "bad new_top value");
   const size_t words = pointer_delta(new_top, dest_addr);
   if (words > 0) {
     ObjectStartArray* start_array = _space_info[space_id].start_array();
     MoveAndUpdateClosure closure(bitmap, cm, start_array, dest_addr, words);
     ParMarkBitMap::IterationStatus status;
     status = bitmap->iterate(&closure, dest_addr, end_addr);
     assert(status == ParMarkBitMap::full, "iteration not complete");
     assert(bitmap->find_obj_beg(closure.source(), end_addr) == end_addr,
            "live objects skipped because closure is full");
   }
 }
 jlong PSParallelCompact::millis_since_last_gc() {
   jlong ret_val = os::javaTimeMillis() - _time_of_last_gc;
   // XXX See note in genCollectedHeap::millis_since_last_gc().
   if (ret_val < 0) {
     NOT_PRODUCT(warning("time warp: %d", ret_val);)
     return 0;
   }
   return ret_val;
 }
 void PSParallelCompact::reset_millis_since_last_gc() {
   _time_of_last_gc = os::javaTimeMillis();
 }
 ParMarkBitMap::IterationStatus MoveAndUpdateClosure::copy_until_full()
 {
   if (source() != destination()) {
     assert(source() > destination(), "must copy to the left");
     Copy::aligned_conjoint_words(source(), destination(), words_remaining());
   }
   update_state(words_remaining());
   assert(is_full(), "sanity");
   return ParMarkBitMap::full;
 }
 void MoveAndUpdateClosure::copy_partial_obj()
 {
   size_t words = words_remaining();
   HeapWord* const range_end = MIN2(source() + words, bitmap()->region_end());
   HeapWord* const end_addr = bitmap()->find_obj_end(source(), range_end);
   if (end_addr < range_end) {
     words = bitmap()->obj_size(source(), end_addr);
   }
   // This test is necessary; if omitted, the pointer updates to a partial object
   // that crosses the dense prefix boundary could be overwritten.
   if (source() != destination()) {
     assert(source() > destination(), "must copy to the left");
     Copy::aligned_conjoint_words(source(), destination(), words);
   }
   update_state(words);
 }
 ParMarkBitMapClosure::IterationStatus
 MoveAndUpdateClosure::do_addr(HeapWord* addr, size_t words) {
   assert(destination() != NULL, "sanity");
   assert(bitmap()->obj_size(addr) == words, "bad size");
   _source = addr;
   assert(PSParallelCompact::summary_data().calc_new_pointer(source()) ==
          destination(), "wrong destination");
   if (words > words_remaining()) {
     return ParMarkBitMap::would_overflow;
   }
   // The start_array must be updated even if the object is not moving.
   if (_start_array != NULL) {
     _start_array->allocate_block(destination());
   }
   if (destination() != source()) {
     assert(destination() < source(), "must copy to the left");
     Copy::aligned_conjoint_words(source(), destination(), words);
   }
   oop moved_oop = (oop) destination();
   moved_oop->update_contents(compaction_manager());
   assert(moved_oop->is_oop_or_null(), "Object should be whole at this point");
   update_state(words);
   assert(destination() == (HeapWord*)moved_oop + moved_oop->size(), "sanity");
   return is_full() ? ParMarkBitMap::full : ParMarkBitMap::incomplete;
 }
 UpdateOnlyClosure::UpdateOnlyClosure(ParMarkBitMap* mbm,
                                      ParCompactionManager* cm,
                                      PSParallelCompact::SpaceId space_id) :
   ParMarkBitMapClosure(mbm, cm),
   _space_id(space_id),
   _start_array(PSParallelCompact::start_array(space_id))
 {
 }
 // Updates the references in the object to their new values.
 ParMarkBitMapClosure::IterationStatus
 UpdateOnlyClosure::do_addr(HeapWord* addr, size_t words) {
   do_addr(addr);
   return ParMarkBitMap::incomplete;
 }
 BitBlockUpdateClosure::BitBlockUpdateClosure(ParMarkBitMap* mbm,
                         ParCompactionManager* cm,
                         size_t chunk_index) :
                         ParMarkBitMapClosure(mbm, cm),
                         _live_data_left(0),
                         _cur_block(0) {
   _chunk_start =
     PSParallelCompact::summary_data().chunk_to_addr(chunk_index);
   _chunk_end =
     PSParallelCompact::summary_data().chunk_to_addr(chunk_index) +
                  ParallelCompactData::ChunkSize;
   _chunk_index = chunk_index;
   _cur_block =
     PSParallelCompact::summary_data().addr_to_block_idx(_chunk_start);
 }
 bool BitBlockUpdateClosure::chunk_contains_cur_block() {
   return ParallelCompactData::chunk_contains_block(_chunk_index, _cur_block);
 }
 void BitBlockUpdateClosure::reset_chunk(size_t chunk_index) {
   DEBUG_ONLY(ParallelCompactData::BlockData::set_cur_phase(7);)
   ParallelCompactData& sd = PSParallelCompact::summary_data();
   _chunk_index = chunk_index;
   _live_data_left = 0;
   _chunk_start = sd.chunk_to_addr(chunk_index);
   _chunk_end = sd.chunk_to_addr(chunk_index) + ParallelCompactData::ChunkSize;
   // The first block in this chunk
   size_t first_block =  sd.addr_to_block_idx(_chunk_start);
   size_t partial_live_size = sd.chunk(chunk_index)->partial_obj_size();
   // Set the offset to 0. By definition it should have that value
   // but it may have been written while processing an earlier chunk.
   if (partial_live_size == 0) {
     // No live object extends onto the chunk.  The first bit
     // in the bit map for the first chunk must be a start bit.
     // Although there may not be any marked bits, it is safe
     // to set it as a start bit.
     sd.block(first_block)->set_start_bit_offset(0);
     sd.block(first_block)->set_first_is_start_bit(true);
   } else if (sd.partial_obj_ends_in_block(first_block)) {
     sd.block(first_block)->set_end_bit_offset(0);
     sd.block(first_block)->set_first_is_start_bit(false);
   } else {
     // The partial object extends beyond the first block.
     // There is no object starting in the first block
     // so the offset and bit parity are not needed.
     // Set the the bit parity to start bit so assertions
     // work when not bit is found.
     sd.block(first_block)->set_end_bit_offset(0);
     sd.block(first_block)->set_first_is_start_bit(false);
   }
   _cur_block = first_block;
 #ifdef ASSERT
   if (sd.block(first_block)->first_is_start_bit()) {
     assert(!sd.partial_obj_ends_in_block(first_block),
       "Partial object cannot end in first block");
   }
   if (PrintGCDetails && Verbose) {
     if (partial_live_size == 1) {
     gclog_or_tty->print_cr("first_block " PTR_FORMAT
       " _offset " PTR_FORMAT
       " _first_is_start_bit %d",
       first_block,
       sd.block(first_block)->raw_offset(),
       sd.block(first_block)->first_is_start_bit());
     }
   }
 #endif
   DEBUG_ONLY(ParallelCompactData::BlockData::set_cur_phase(17);)
 }
 // This method is called when a object has been found (both beginning
 // and end of the object) in the range of iteration.  This method is
 // calculating the words of live data to the left of a block.  That live
 // data includes any object starting to the left of the block (i.e.,
 // the live-data-to-the-left of block AAA will include the full size
 // of any object entering AAA).
 ParMarkBitMapClosure::IterationStatus
 BitBlockUpdateClosure::do_addr(HeapWord* addr, size_t words) {
   // add the size to the block data.
   HeapWord* obj = addr;
   ParallelCompactData& sd = PSParallelCompact::summary_data();
   assert(bitmap()->obj_size(obj) == words, "bad size");
   assert(_chunk_start <= obj, "object is not in chunk");
   assert(obj + words <= _chunk_end, "object is not in chunk");
   // Update the live data to the left
   size_t prev_live_data_left = _live_data_left;
   _live_data_left = _live_data_left + words;
   // Is this object in the current block.
   size_t block_of_obj = sd.addr_to_block_idx(obj);
   size_t block_of_obj_last = sd.addr_to_block_idx(obj + words - 1);
   HeapWord* block_of_obj_last_addr = sd.block_to_addr(block_of_obj_last);
   if (_cur_block < block_of_obj) {
     //
     // No object crossed the block boundary and this object was found
     // on the other side of the block boundary.  Update the offset for
     // the new block with the data size that does not include this object.
     //
     // The first bit in block_of_obj is a start bit except in the
     // case where the partial object for the chunk extends into
     // this block.
     if (sd.partial_obj_ends_in_block(block_of_obj)) {
       sd.block(block_of_obj)->set_end_bit_offset(prev_live_data_left);
     } else {
       sd.block(block_of_obj)->set_start_bit_offset(prev_live_data_left);
     }
     // Does this object pass beyond the its block?
     if (block_of_obj < block_of_obj_last) {
       // Object crosses block boundary.  Two blocks need to be udpated:
       //        the current block where the object started
       //        the block where the object ends
       //
       // The offset for blocks with no objects starting in them
       // (e.g., blocks between _cur_block and  block_of_obj_last)
       // should not be needed.
       // Note that block_of_obj_last may be in another chunk.  If so,
       // it should be overwritten later.  This is a problem (writting
       // into a block in a later chunk) for parallel execution.
       assert(obj < block_of_obj_last_addr,
         "Object should start in previous block");
       // obj is crossing into block_of_obj_last so the first bit
       // is and end bit.
       sd.block(block_of_obj_last)->set_end_bit_offset(_live_data_left);
       _cur_block = block_of_obj_last;
     } else {
       // _first_is_start_bit has already been set correctly
       // in the if-then-else above so don't reset it here.
       _cur_block = block_of_obj;
     }
   } else {
     // The current block only changes if the object extends beyound
     // the block it starts in.
     //
     // The object starts in the current block.
     // Does this object pass beyond the end of it?
     if (block_of_obj < block_of_obj_last) {
       // Object crosses block boundary.
       // See note above on possible blocks between block_of_obj and
       // block_of_obj_last
       assert(obj < block_of_obj_last_addr,
         "Object should start in previous block");
       sd.block(block_of_obj_last)->set_end_bit_offset(_live_data_left);
       _cur_block = block_of_obj_last;
     }
   }
   // Return incomplete if there are more blocks to be done.
   if (chunk_contains_cur_block()) {
     return ParMarkBitMap::incomplete;
   }
   return ParMarkBitMap::complete;
 }
 // Verify the new location using the forwarding pointer
 // from MarkSweep::mark_sweep_phase2().  Set the mark_word
 // to the initial value.
 ParMarkBitMapClosure::IterationStatus
 PSParallelCompact::VerifyUpdateClosure::do_addr(HeapWord* addr, size_t words) {
   // The second arg (words) is not used.
   oop obj = (oop) addr;
   HeapWord* forwarding_ptr = (HeapWord*) obj->mark()->decode_pointer();
   HeapWord* new_pointer = summary_data().calc_new_pointer(obj);
   if (forwarding_ptr == NULL) {
     // The object is dead or not moving.
     assert(bitmap()->is_unmarked(obj) || (new_pointer == (HeapWord*) obj),
            "Object liveness is wrong.");
     return ParMarkBitMap::incomplete;
   }
   assert(UseParallelOldGCDensePrefix ||
          (HeapMaximumCompactionInterval > 1) ||
          (MarkSweepAlwaysCompactCount > 1) ||
          (forwarding_ptr == new_pointer),
     "Calculation of new location is incorrect");
   return ParMarkBitMap::incomplete;
 }
 // Reset objects modified for debug checking.
 ParMarkBitMapClosure::IterationStatus
 PSParallelCompact::ResetObjectsClosure::do_addr(HeapWord* addr, size_t words) {
   // The second arg (words) is not used.
   oop obj = (oop) addr;
   obj->init_mark();
   return ParMarkBitMap::incomplete;
 }
 // Prepare for compaction.  This method is executed once
 // (i.e., by a single thread) before compaction.
 // Save the updated location of the intArrayKlassObj for
 // filling holes in the dense prefix.
 void PSParallelCompact::compact_prologue() {
   _updated_int_array_klass_obj = (klassOop)
     summary_data().calc_new_pointer(Universe::intArrayKlassObj());
 }
 // The initial implementation of this method created a field
 // _next_compaction_space_id in SpaceInfo and initialized
 // that field in SpaceInfo::initialize_space_info().  That
 // required that _next_compaction_space_id be declared a
 // SpaceId in SpaceInfo and that would have required that
 // either SpaceId be declared in a separate class or that
 // it be declared in SpaceInfo.  It didn't seem consistent
 // to declare it in SpaceInfo (didn't really fit logically).
 // Alternatively, defining a separate class to define SpaceId
 // seem excessive.  This implementation is simple and localizes
 // the knowledge.
 PSParallelCompact::SpaceId
 PSParallelCompact::next_compaction_space_id(SpaceId id) {
   assert(id < last_space_id, "id out of range");
   switch (id) {
     case perm_space_id :
       return last_space_id;
     case old_space_id :
       return eden_space_id;
     case eden_space_id :
       return from_space_id;
     case from_space_id :
       return to_space_id;
     case to_space_id :
       return last_space_id;
     default:
       assert(false, "Bad space id");
       return last_space_id;
   }
 }
 // Here temporarily for debugging
 #ifdef ASSERT
   size_t ParallelCompactData::block_idx(BlockData* block) {
     size_t index = pointer_delta(block,
       PSParallelCompact::summary_data()._block_data, sizeof(BlockData));
     return index;
   }
 #endif

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/gc_implementation/parallelScavenge/psParallelCompact.cpp@1fdb98a17101 (annotated)

src/share/vm/gc_implementation/parallelScavenge/psParallelCompact.cpp