Mercurial > jdk8-mips64-public > hotspot / file revision

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  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

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  * 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).

  *

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  * 2 along with this work; if not, write to the Free Software Foundation,

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 #include "precompiled.hpp"

 #include "gc_implementation/concurrentMarkSweep/cmsLockVerifier.hpp"

 #include "gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.hpp"

 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepGeneration.inline.hpp"

 #include "gc_implementation/concurrentMarkSweep/concurrentMarkSweepThread.hpp"

 #include "gc_implementation/shared/liveRange.hpp"

 #include "gc_implementation/shared/spaceDecorator.hpp"

 #include "gc_interface/collectedHeap.inline.hpp"

 #include "memory/allocation.inline.hpp"

 #include "memory/blockOffsetTable.inline.hpp"

 #include "memory/resourceArea.hpp"

 #include "memory/universe.inline.hpp"

 #include "oops/oop.inline.hpp"

 #include "runtime/globals.hpp"

 #include "runtime/handles.inline.hpp"

 #include "runtime/init.hpp"

 #include "runtime/java.hpp"

 #include "runtime/vmThread.hpp"

 #include "utilities/copy.hpp"

 /////////////////////////////////////////////////////////////////////////

 //// CompactibleFreeListSpace

 /////////////////////////////////////////////////////////////////////////

 // highest ranked  free list lock rank

 int CompactibleFreeListSpace::_lockRank = Mutex::leaf + 3;

 // Defaults are 0 so things will break badly if incorrectly initialized.

 size_t CompactibleFreeListSpace::IndexSetStart  = 0;

 size_t CompactibleFreeListSpace::IndexSetStride = 0;

 size_t MinChunkSize = 0;

 void CompactibleFreeListSpace::set_cms_values() {

   // Set CMS global values

   assert(MinChunkSize == 0, "already set");

   // MinChunkSize should be a multiple of MinObjAlignment and be large enough

   // for chunks to contain a FreeChunk.

   size_t min_chunk_size_in_bytes = align_size_up(sizeof(FreeChunk), MinObjAlignmentInBytes);

   MinChunkSize = min_chunk_size_in_bytes / BytesPerWord;

   assert(IndexSetStart == 0 && IndexSetStride == 0, "already set");

   IndexSetStart  = MinChunkSize;

   IndexSetStride = MinObjAlignment;

 }

 // Constructor

 CompactibleFreeListSpace::CompactibleFreeListSpace(BlockOffsetSharedArray* bs,

   MemRegion mr, bool use_adaptive_freelists,

   FreeBlockDictionary<FreeChunk>::DictionaryChoice dictionaryChoice) :

   _dictionaryChoice(dictionaryChoice),

   _adaptive_freelists(use_adaptive_freelists),

   _bt(bs, mr),

   // free list locks are in the range of values taken by _lockRank

   // This range currently is [_leaf+2, _leaf+3]

   // Note: this requires that CFLspace c'tors

   // are called serially in the order in which the locks are

   // are acquired in the program text. This is true today.

   _freelistLock(_lockRank--, "CompactibleFreeListSpace._lock", true),

   _parDictionaryAllocLock(Mutex::leaf - 1,  // == rank(ExpandHeap_lock) - 1

                           "CompactibleFreeListSpace._dict_par_lock", true),

   _rescan_task_size(CardTableModRefBS::card_size_in_words * BitsPerWord *

                     CMSRescanMultiple),

   _marking_task_size(CardTableModRefBS::card_size_in_words * BitsPerWord *

                     CMSConcMarkMultiple),

   _collector(NULL)

 {

   assert(sizeof(FreeChunk) / BytesPerWord <= MinChunkSize,

          "FreeChunk is larger than expected");

   _bt.set_space(this);

   initialize(mr, SpaceDecorator::Clear, SpaceDecorator::Mangle);

   // We have all of "mr", all of which we place in the dictionary

   // as one big chunk. We'll need to decide here which of several

   // possible alternative dictionary implementations to use. For

   // now the choice is easy, since we have only one working

   // implementation, namely, the simple binary tree (splaying

   // temporarily disabled).

   switch (dictionaryChoice) {

     case FreeBlockDictionary<FreeChunk>::dictionaryBinaryTree:

       _dictionary = new BinaryTreeDictionary<FreeChunk, AdaptiveFreeList>(mr);

       break;

     case FreeBlockDictionary<FreeChunk>::dictionarySplayTree:

     case FreeBlockDictionary<FreeChunk>::dictionarySkipList:

     default:

       warning("dictionaryChoice: selected option not understood; using"

               " default BinaryTreeDictionary implementation instead.");

   }

   assert(_dictionary != NULL, "CMS dictionary initialization");

   // The indexed free lists are initially all empty and are lazily

   // filled in on demand. Initialize the array elements to NULL.

   initializeIndexedFreeListArray();

   // Not using adaptive free lists assumes that allocation is first

   // from the linAB's.  Also a cms perm gen which can be compacted

   // has to have the klass's klassKlass allocated at a lower

   // address in the heap than the klass so that the klassKlass is

   // moved to its new location before the klass is moved.

   // Set the _refillSize for the linear allocation blocks

   if (!use_adaptive_freelists) {

     FreeChunk* fc = _dictionary->get_chunk(mr.word_size());

     // The small linAB initially has all the space and will allocate

     // a chunk of any size.

     HeapWord* addr = (HeapWord*) fc;

     _smallLinearAllocBlock.set(addr, fc->size() ,

       1024*SmallForLinearAlloc, fc->size());

     // Note that _unallocated_block is not updated here.

     // Allocations from the linear allocation block should

     // update it.

   } else {

     _smallLinearAllocBlock.set(0, 0, 1024*SmallForLinearAlloc,

                                SmallForLinearAlloc);

   }

   // CMSIndexedFreeListReplenish should be at least 1

   CMSIndexedFreeListReplenish = MAX2((uintx)1, CMSIndexedFreeListReplenish);

   _promoInfo.setSpace(this);

   if (UseCMSBestFit) {

     _fitStrategy = FreeBlockBestFitFirst;

   } else {

     _fitStrategy = FreeBlockStrategyNone;

   }

   check_free_list_consistency();

   // Initialize locks for parallel case.

   if (CollectedHeap::use_parallel_gc_threads()) {

     for (size_t i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) {

       _indexedFreeListParLocks[i] = new Mutex(Mutex::leaf - 1, // == ExpandHeap_lock - 1

                                               "a freelist par lock",

                                               true);

       if (_indexedFreeListParLocks[i] == NULL)

         vm_exit_during_initialization("Could not allocate a par lock");

       DEBUG_ONLY(

         _indexedFreeList[i].set_protecting_lock(_indexedFreeListParLocks[i]);

       )

     }

     _dictionary->set_par_lock(&_parDictionaryAllocLock);

   }

 }

 // Like CompactibleSpace forward() but always calls cross_threshold() to

 // update the block offset table.  Removed initialize_threshold call because

 // CFLS does not use a block offset array for contiguous spaces.

 HeapWord* CompactibleFreeListSpace::forward(oop q, size_t size,

                                     CompactPoint* cp, HeapWord* compact_top) {

   // q is alive

   // First check if we should switch compaction space

   assert(this == cp->space, "'this' should be current compaction space.");

   size_t compaction_max_size = pointer_delta(end(), compact_top);

   assert(adjustObjectSize(size) == cp->space->adjust_object_size_v(size),

     "virtual adjustObjectSize_v() method is not correct");

   size_t adjusted_size = adjustObjectSize(size);

   assert(compaction_max_size >= MinChunkSize || compaction_max_size == 0,

          "no small fragments allowed");

   assert(minimum_free_block_size() == MinChunkSize,

          "for de-virtualized reference below");

   // Can't leave a nonzero size, residual fragment smaller than MinChunkSize

   if (adjusted_size + MinChunkSize > compaction_max_size &&

       adjusted_size != compaction_max_size) {

     do {

       // switch to next compaction space

       cp->space->set_compaction_top(compact_top);

       cp->space = cp->space->next_compaction_space();

       if (cp->space == NULL) {

         cp->gen = GenCollectedHeap::heap()->prev_gen(cp->gen);

         assert(cp->gen != NULL, "compaction must succeed");

         cp->space = cp->gen->first_compaction_space();

         assert(cp->space != NULL, "generation must have a first compaction space");

       }

       compact_top = cp->space->bottom();

       cp->space->set_compaction_top(compact_top);

       // The correct adjusted_size may not be the same as that for this method

       // (i.e., cp->space may no longer be "this" so adjust the size again.

       // Use the virtual method which is not used above to save the virtual

       // dispatch.

       adjusted_size = cp->space->adjust_object_size_v(size);

       compaction_max_size = pointer_delta(cp->space->end(), compact_top);

       assert(cp->space->minimum_free_block_size() == 0, "just checking");

     } while (adjusted_size > compaction_max_size);

   }

   // store the forwarding pointer into the mark word

   if ((HeapWord*)q != compact_top) {

     q->forward_to(oop(compact_top));

     assert(q->is_gc_marked(), "encoding the pointer should preserve the mark");

   } else {

     // if the object isn't moving we can just set the mark to the default

     // mark and handle it specially later on.

     q->init_mark();

     assert(q->forwardee() == NULL, "should be forwarded to NULL");

   }

   VALIDATE_MARK_SWEEP_ONLY(MarkSweep::register_live_oop(q, adjusted_size));

   compact_top += adjusted_size;

   // we need to update the offset table so that the beginnings of objects can be

   // found during scavenge.  Note that we are updating the offset table based on

   // where the object will be once the compaction phase finishes.

   // Always call cross_threshold().  A contiguous space can only call it when

   // the compaction_top exceeds the current threshold but not for an

   // non-contiguous space.

   cp->threshold =

     cp->space->cross_threshold(compact_top - adjusted_size, compact_top);

   return compact_top;

 }

 // A modified copy of OffsetTableContigSpace::cross_threshold() with _offsets -> _bt

 // and use of single_block instead of alloc_block.  The name here is not really

 // appropriate - maybe a more general name could be invented for both the

 // contiguous and noncontiguous spaces.

 HeapWord* CompactibleFreeListSpace::cross_threshold(HeapWord* start, HeapWord* the_end) {

   _bt.single_block(start, the_end);

   return end();

 }

 // Initialize them to NULL.

 void CompactibleFreeListSpace::initializeIndexedFreeListArray() {

   for (size_t i = 0; i < IndexSetSize; i++) {

     // Note that on platforms where objects are double word aligned,

     // the odd array elements are not used.  It is convenient, however,

     // to map directly from the object size to the array element.

     _indexedFreeList[i].reset(IndexSetSize);

     _indexedFreeList[i].set_size(i);

     assert(_indexedFreeList[i].count() == 0, "reset check failed");

     assert(_indexedFreeList[i].head() == NULL, "reset check failed");

     assert(_indexedFreeList[i].tail() == NULL, "reset check failed");

     assert(_indexedFreeList[i].hint() == IndexSetSize, "reset check failed");

   }

 }

 void CompactibleFreeListSpace::resetIndexedFreeListArray() {

   for (size_t i = 1; i < IndexSetSize; i++) {

     assert(_indexedFreeList[i].size() == (size_t) i,

       "Indexed free list sizes are incorrect");

     _indexedFreeList[i].reset(IndexSetSize);

     assert(_indexedFreeList[i].count() == 0, "reset check failed");

     assert(_indexedFreeList[i].head() == NULL, "reset check failed");

     assert(_indexedFreeList[i].tail() == NULL, "reset check failed");

     assert(_indexedFreeList[i].hint() == IndexSetSize, "reset check failed");

   }

 }

 void CompactibleFreeListSpace::reset(MemRegion mr) {

   resetIndexedFreeListArray();

   dictionary()->reset();

   if (BlockOffsetArrayUseUnallocatedBlock) {

     assert(end() == mr.end(), "We are compacting to the bottom of CMS gen");

     // Everything's allocated until proven otherwise.

     _bt.set_unallocated_block(end());

   }

   if (!mr.is_empty()) {

     assert(mr.word_size() >= MinChunkSize, "Chunk size is too small");

     _bt.single_block(mr.start(), mr.word_size());

     FreeChunk* fc = (FreeChunk*) mr.start();

     fc->set_size(mr.word_size());

     if (mr.word_size() >= IndexSetSize ) {

       returnChunkToDictionary(fc);

     } else {

       _bt.verify_not_unallocated((HeapWord*)fc, fc->size());

       _indexedFreeList[mr.word_size()].return_chunk_at_head(fc);

     }

   }

   _promoInfo.reset();

   _smallLinearAllocBlock._ptr = NULL;

   _smallLinearAllocBlock._word_size = 0;

 }

 void CompactibleFreeListSpace::reset_after_compaction() {

   // Reset the space to the new reality - one free chunk.

   MemRegion mr(compaction_top(), end());

   reset(mr);

   // Now refill the linear allocation block(s) if possible.

   if (_adaptive_freelists) {

     refillLinearAllocBlocksIfNeeded();

   } else {

     // Place as much of mr in the linAB as we can get,

     // provided it was big enough to go into the dictionary.

     FreeChunk* fc = dictionary()->find_largest_dict();

     if (fc != NULL) {

       assert(fc->size() == mr.word_size(),

              "Why was the chunk broken up?");

       removeChunkFromDictionary(fc);

       HeapWord* addr = (HeapWord*) fc;

       _smallLinearAllocBlock.set(addr, fc->size() ,

         1024*SmallForLinearAlloc, fc->size());

       // Note that _unallocated_block is not updated here.

     }

   }

 }

 // Walks the entire dictionary, returning a coterminal

 // chunk, if it exists. Use with caution since it involves

 // a potentially complete walk of a potentially large tree.

 FreeChunk* CompactibleFreeListSpace::find_chunk_at_end() {

   assert_lock_strong(&_freelistLock);

   return dictionary()->find_chunk_ends_at(end());

 }

 #ifndef PRODUCT

 void CompactibleFreeListSpace::initializeIndexedFreeListArrayReturnedBytes() {

   for (size_t i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) {

     _indexedFreeList[i].allocation_stats()->set_returned_bytes(0);

   }

 }

 size_t CompactibleFreeListSpace::sumIndexedFreeListArrayReturnedBytes() {

   size_t sum = 0;

   for (size_t i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) {

     sum += _indexedFreeList[i].allocation_stats()->returned_bytes();

   }

   return sum;

 }

 size_t CompactibleFreeListSpace::totalCountInIndexedFreeLists() const {

   size_t count = 0;

   for (size_t i = IndexSetStart; i < IndexSetSize; i++) {

     debug_only(

       ssize_t total_list_count = 0;

       for (FreeChunk* fc = _indexedFreeList[i].head(); fc != NULL;

          fc = fc->next()) {

         total_list_count++;

       }

       assert(total_list_count ==  _indexedFreeList[i].count(),

         "Count in list is incorrect");

     )

     count += _indexedFreeList[i].count();

   }

   return count;

 }

 size_t CompactibleFreeListSpace::totalCount() {

   size_t num = totalCountInIndexedFreeLists();

   num +=  dictionary()->total_count();

   if (_smallLinearAllocBlock._word_size != 0) {

     num++;

   }

   return num;

 }

 #endif

 bool CompactibleFreeListSpace::is_free_block(const HeapWord* p) const {

   FreeChunk* fc = (FreeChunk*) p;

   return fc->is_free();

 }

 size_t CompactibleFreeListSpace::used() const {

   return capacity() - free();

 }

 size_t CompactibleFreeListSpace::free() const {

   // "MT-safe, but not MT-precise"(TM), if you will: i.e.

   // if you do this while the structures are in flux you

   // may get an approximate answer only; for instance

   // because there is concurrent allocation either

   // directly by mutators or for promotion during a GC.

   // It's "MT-safe", however, in the sense that you are guaranteed

   // not to crash and burn, for instance, because of walking

   // pointers that could disappear as you were walking them.

   // The approximation is because the various components

   // that are read below are not read atomically (and

   // further the computation of totalSizeInIndexedFreeLists()

   // is itself a non-atomic computation. The normal use of

   // this is during a resize operation at the end of GC

   // and at that time you are guaranteed to get the

   // correct actual value. However, for instance, this is

   // also read completely asynchronously by the "perf-sampler"

   // that supports jvmstat, and you are apt to see the values

   // flicker in such cases.

   assert(_dictionary != NULL, "No _dictionary?");

   return (_dictionary->total_chunk_size(DEBUG_ONLY(freelistLock())) +

           totalSizeInIndexedFreeLists() +

           _smallLinearAllocBlock._word_size) * HeapWordSize;

 }

 size_t CompactibleFreeListSpace::max_alloc_in_words() const {

   assert(_dictionary != NULL, "No _dictionary?");

   assert_locked();

   size_t res = _dictionary->max_chunk_size();

   res = MAX2(res, MIN2(_smallLinearAllocBlock._word_size,

                        (size_t) SmallForLinearAlloc - 1));

   // XXX the following could potentially be pretty slow;

   // should one, pesimally for the rare cases when res

   // caclulated above is less than IndexSetSize,

   // just return res calculated above? My reasoning was that

   // those cases will be so rare that the extra time spent doesn't

   // really matter....

   // Note: do not change the loop test i >= res + IndexSetStride

   // to i > res below, because i is unsigned and res may be zero.

   for (size_t i = IndexSetSize - 1; i >= res + IndexSetStride;

        i -= IndexSetStride) {

     if (_indexedFreeList[i].head() != NULL) {

       assert(_indexedFreeList[i].count() != 0, "Inconsistent FreeList");

       return i;

     }

   }

   return res;

 }

 void LinearAllocBlock::print_on(outputStream* st) const {

   st->print_cr(" LinearAllocBlock: ptr = " PTR_FORMAT ", word_size = " SIZE_FORMAT

             ", refillsize = " SIZE_FORMAT ", allocation_size_limit = " SIZE_FORMAT,

             _ptr, _word_size, _refillSize, _allocation_size_limit);

 }

 void CompactibleFreeListSpace::print_on(outputStream* st) const {

   st->print_cr("COMPACTIBLE FREELIST SPACE");

   st->print_cr(" Space:");

   Space::print_on(st);

   st->print_cr("promoInfo:");

   _promoInfo.print_on(st);

   st->print_cr("_smallLinearAllocBlock");

   _smallLinearAllocBlock.print_on(st);

   // dump_memory_block(_smallLinearAllocBlock->_ptr, 128);

   st->print_cr(" _fitStrategy = %s, _adaptive_freelists = %s",

                _fitStrategy?"true":"false", _adaptive_freelists?"true":"false");

 }

 void CompactibleFreeListSpace::print_indexed_free_lists(outputStream* st)

 const {

   reportIndexedFreeListStatistics();

   gclog_or_tty->print_cr("Layout of Indexed Freelists");

   gclog_or_tty->print_cr("---------------------------");

   AdaptiveFreeList<FreeChunk>::print_labels_on(st, "size");

   for (size_t i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) {

     _indexedFreeList[i].print_on(gclog_or_tty);

     for (FreeChunk* fc = _indexedFreeList[i].head(); fc != NULL;

          fc = fc->next()) {

       gclog_or_tty->print_cr("\t[" PTR_FORMAT "," PTR_FORMAT ")  %s",

                           fc, (HeapWord*)fc + i,

                           fc->cantCoalesce() ? "\t CC" : "");

     }

   }

 }

 void CompactibleFreeListSpace::print_promo_info_blocks(outputStream* st)

 const {

   _promoInfo.print_on(st);

 }

 void CompactibleFreeListSpace::print_dictionary_free_lists(outputStream* st)

 const {

   _dictionary->report_statistics();

   st->print_cr("Layout of Freelists in Tree");

   st->print_cr("---------------------------");

   _dictionary->print_free_lists(st);

 }

 class BlkPrintingClosure: public BlkClosure {

   const CMSCollector*             _collector;

   const CompactibleFreeListSpace* _sp;

   const CMSBitMap*                _live_bit_map;

   const bool                      _post_remark;

   outputStream*                   _st;

 public:

   BlkPrintingClosure(const CMSCollector* collector,

                      const CompactibleFreeListSpace* sp,

                      const CMSBitMap* live_bit_map,

                      outputStream* st):

     _collector(collector),

     _sp(sp),

     _live_bit_map(live_bit_map),

     _post_remark(collector->abstract_state() > CMSCollector::FinalMarking),

     _st(st) { }

   size_t do_blk(HeapWord* addr);

 };

 size_t BlkPrintingClosure::do_blk(HeapWord* addr) {

   size_t sz = _sp->block_size_no_stall(addr, _collector);

   assert(sz != 0, "Should always be able to compute a size");

   if (_sp->block_is_obj(addr)) {

     const bool dead = _post_remark && !_live_bit_map->isMarked(addr);

     _st->print_cr(PTR_FORMAT ": %s object of size " SIZE_FORMAT "%s",

       addr,

       dead ? "dead" : "live",

       sz,

       (!dead && CMSPrintObjectsInDump) ? ":" : ".");

     if (CMSPrintObjectsInDump && !dead) {

       oop(addr)->print_on(_st);

       _st->print_cr("--------------------------------------");

     }

   } else { // free block

     _st->print_cr(PTR_FORMAT ": free block of size " SIZE_FORMAT "%s",

       addr, sz, CMSPrintChunksInDump ? ":" : ".");

     if (CMSPrintChunksInDump) {

       ((FreeChunk*)addr)->print_on(_st);

       _st->print_cr("--------------------------------------");

     }

   }

   return sz;

 }

 void CompactibleFreeListSpace::dump_at_safepoint_with_locks(CMSCollector* c,

   outputStream* st) {

   st->print_cr("\n=========================");

   st->print_cr("Block layout in CMS Heap:");

   st->print_cr("=========================");

   BlkPrintingClosure  bpcl(c, this, c->markBitMap(), st);

   blk_iterate(&bpcl);

   st->print_cr("\n=======================================");

   st->print_cr("Order & Layout of Promotion Info Blocks");

   st->print_cr("=======================================");

   print_promo_info_blocks(st);

   st->print_cr("\n===========================");

   st->print_cr("Order of Indexed Free Lists");

   st->print_cr("=========================");

   print_indexed_free_lists(st);

   st->print_cr("\n=================================");

   st->print_cr("Order of Free Lists in Dictionary");

   st->print_cr("=================================");

   print_dictionary_free_lists(st);

 }

 void CompactibleFreeListSpace::reportFreeListStatistics() const {

   assert_lock_strong(&_freelistLock);

   assert(PrintFLSStatistics != 0, "Reporting error");

   _dictionary->report_statistics();

   if (PrintFLSStatistics > 1) {

     reportIndexedFreeListStatistics();

     size_t total_size = totalSizeInIndexedFreeLists() +

                        _dictionary->total_chunk_size(DEBUG_ONLY(freelistLock()));

     gclog_or_tty->print(" free=%ld frag=%1.4f\n", total_size, flsFrag());

   }

 }

 void CompactibleFreeListSpace::reportIndexedFreeListStatistics() const {

   assert_lock_strong(&_freelistLock);

   gclog_or_tty->print("Statistics for IndexedFreeLists:\n"

                       "--------------------------------\n");

   size_t total_size = totalSizeInIndexedFreeLists();

   size_t   free_blocks = numFreeBlocksInIndexedFreeLists();

   gclog_or_tty->print("Total Free Space: %d\n", total_size);

   gclog_or_tty->print("Max   Chunk Size: %d\n", maxChunkSizeInIndexedFreeLists());

   gclog_or_tty->print("Number of Blocks: %d\n", free_blocks);

   if (free_blocks != 0) {

     gclog_or_tty->print("Av.  Block  Size: %d\n", total_size/free_blocks);

   }

 }

 size_t CompactibleFreeListSpace::numFreeBlocksInIndexedFreeLists() const {

   size_t res = 0;

   for (size_t i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) {

     debug_only(

       ssize_t recount = 0;

       for (FreeChunk* fc = _indexedFreeList[i].head(); fc != NULL;

          fc = fc->next()) {

         recount += 1;

       }

       assert(recount == _indexedFreeList[i].count(),

         "Incorrect count in list");

     )

     res += _indexedFreeList[i].count();

   }

   return res;

 }

 size_t CompactibleFreeListSpace::maxChunkSizeInIndexedFreeLists() const {

   for (size_t i = IndexSetSize - 1; i != 0; i -= IndexSetStride) {

     if (_indexedFreeList[i].head() != NULL) {

       assert(_indexedFreeList[i].count() != 0, "Inconsistent FreeList");

       return (size_t)i;

     }

   }

   return 0;

 }

 void CompactibleFreeListSpace::set_end(HeapWord* value) {

   HeapWord* prevEnd = end();

   assert(prevEnd != value, "unnecessary set_end call");

   assert(prevEnd == NULL || !BlockOffsetArrayUseUnallocatedBlock || value >= unallocated_block(),

         "New end is below unallocated block");

   _end = value;

   if (prevEnd != NULL) {

     // Resize the underlying block offset table.

     _bt.resize(pointer_delta(value, bottom()));

     if (value <= prevEnd) {

       assert(!BlockOffsetArrayUseUnallocatedBlock || value >= unallocated_block(),

              "New end is below unallocated block");

     } else {

       // Now, take this new chunk and add it to the free blocks.

       // Note that the BOT has not yet been updated for this block.

       size_t newFcSize = pointer_delta(value, prevEnd);

       // XXX This is REALLY UGLY and should be fixed up. XXX

       if (!_adaptive_freelists && _smallLinearAllocBlock._ptr == NULL) {

         // Mark the boundary of the new block in BOT

         _bt.mark_block(prevEnd, value);

         // put it all in the linAB

         if (ParallelGCThreads == 0) {

           _smallLinearAllocBlock._ptr = prevEnd;

           _smallLinearAllocBlock._word_size = newFcSize;

           repairLinearAllocBlock(&_smallLinearAllocBlock);

         } else { // ParallelGCThreads > 0

           MutexLockerEx x(parDictionaryAllocLock(),

                           Mutex::_no_safepoint_check_flag);

           _smallLinearAllocBlock._ptr = prevEnd;

           _smallLinearAllocBlock._word_size = newFcSize;

           repairLinearAllocBlock(&_smallLinearAllocBlock);

         }

         // Births of chunks put into a LinAB are not recorded.  Births

         // of chunks as they are allocated out of a LinAB are.

       } else {

         // Add the block to the free lists, if possible coalescing it

         // with the last free block, and update the BOT and census data.

         addChunkToFreeListsAtEndRecordingStats(prevEnd, newFcSize);

       }

     }

   }

 }

 class FreeListSpace_DCTOC : public Filtering_DCTOC {

   CompactibleFreeListSpace* _cfls;

   CMSCollector* _collector;

 protected:

   // Override.

 #define walk_mem_region_with_cl_DECL(ClosureType)                       \

   virtual void walk_mem_region_with_cl(MemRegion mr,                    \

                                        HeapWord* bottom, HeapWord* top, \

                                        ClosureType* cl);                \

       void walk_mem_region_with_cl_par(MemRegion mr,                    \

                                        HeapWord* bottom, HeapWord* top, \

                                        ClosureType* cl);                \

     void walk_mem_region_with_cl_nopar(MemRegion mr,                    \

                                        HeapWord* bottom, HeapWord* top, \

                                        ClosureType* cl)

   walk_mem_region_with_cl_DECL(ExtendedOopClosure);

   walk_mem_region_with_cl_DECL(FilteringClosure);

 public:

   FreeListSpace_DCTOC(CompactibleFreeListSpace* sp,

                       CMSCollector* collector,

                       ExtendedOopClosure* cl,

                       CardTableModRefBS::PrecisionStyle precision,

                       HeapWord* boundary) :

     Filtering_DCTOC(sp, cl, precision, boundary),

     _cfls(sp), _collector(collector) {}

 };

 // We de-virtualize the block-related calls below, since we know that our

 // space is a CompactibleFreeListSpace.

 #define FreeListSpace_DCTOC__walk_mem_region_with_cl_DEFN(ClosureType)          \

 void FreeListSpace_DCTOC::walk_mem_region_with_cl(MemRegion mr,                 \

                                                  HeapWord* bottom,              \

                                                  HeapWord* top,                 \

                                                  ClosureType* cl) {             \

    bool is_par = SharedHeap::heap()->n_par_threads() > 0;                       \

    if (is_par) {                                                                \

      assert(SharedHeap::heap()->n_par_threads() ==                              \

             SharedHeap::heap()->workers()->active_workers(), "Mismatch");       \

      walk_mem_region_with_cl_par(mr, bottom, top, cl);                          \

    } else {                                                                     \

      walk_mem_region_with_cl_nopar(mr, bottom, top, cl);                        \

    }                                                                            \

 }                                                                               \

 void FreeListSpace_DCTOC::walk_mem_region_with_cl_par(MemRegion mr,             \

                                                       HeapWord* bottom,         \

                                                       HeapWord* top,            \

                                                       ClosureType* cl) {        \

   /* Skip parts that are before "mr", in case "block_start" sent us             \

      back too far. */                                                           \

   HeapWord* mr_start = mr.start();                                              \

   size_t bot_size = _cfls->CompactibleFreeListSpace::block_size(bottom);        \

   HeapWord* next = bottom + bot_size;                                           \

   while (next < mr_start) {                                                     \

     bottom = next;                                                              \

     bot_size = _cfls->CompactibleFreeListSpace::block_size(bottom);             \

     next = bottom + bot_size;                                                   \

   }                                                                             \

                                                                                 \

   while (bottom < top) {                                                        \

     if (_cfls->CompactibleFreeListSpace::block_is_obj(bottom) &&                \

         !_cfls->CompactibleFreeListSpace::obj_allocated_since_save_marks(       \

                     oop(bottom)) &&                                             \

         !_collector->CMSCollector::is_dead_obj(oop(bottom))) {                  \

       size_t word_sz = oop(bottom)->oop_iterate(cl, mr);                        \

       bottom += _cfls->adjustObjectSize(word_sz);                               \

     } else {                                                                    \

       bottom += _cfls->CompactibleFreeListSpace::block_size(bottom);            \

     }                                                                           \

   }                                                                             \

 }                                                                               \

 void FreeListSpace_DCTOC::walk_mem_region_with_cl_nopar(MemRegion mr,           \

                                                         HeapWord* bottom,       \

                                                         HeapWord* top,          \

                                                         ClosureType* cl) {      \

   /* Skip parts that are before "mr", in case "block_start" sent us             \

      back too far. */                                                           \

   HeapWord* mr_start = mr.start();                                              \

   size_t bot_size = _cfls->CompactibleFreeListSpace::block_size_nopar(bottom);  \

   HeapWord* next = bottom + bot_size;                                           \

   while (next < mr_start) {                                                     \

     bottom = next;                                                              \

     bot_size = _cfls->CompactibleFreeListSpace::block_size_nopar(bottom);       \

     next = bottom + bot_size;                                                   \

   }                                                                             \

                                                                                 \

   while (bottom < top) {                                                        \

     if (_cfls->CompactibleFreeListSpace::block_is_obj_nopar(bottom) &&          \

         !_cfls->CompactibleFreeListSpace::obj_allocated_since_save_marks(       \

                     oop(bottom)) &&                                             \

         !_collector->CMSCollector::is_dead_obj(oop(bottom))) {                  \

       size_t word_sz = oop(bottom)->oop_iterate(cl, mr);                        \

       bottom += _cfls->adjustObjectSize(word_sz);                               \

     } else {                                                                    \

       bottom += _cfls->CompactibleFreeListSpace::block_size_nopar(bottom);      \

     }                                                                           \

   }                                                                             \

 }

 // (There are only two of these, rather than N, because the split is due

 // only to the introduction of the FilteringClosure, a local part of the

 // impl of this abstraction.)

 FreeListSpace_DCTOC__walk_mem_region_with_cl_DEFN(ExtendedOopClosure)

 FreeListSpace_DCTOC__walk_mem_region_with_cl_DEFN(FilteringClosure)

 DirtyCardToOopClosure*

 CompactibleFreeListSpace::new_dcto_cl(ExtendedOopClosure* cl,

                                       CardTableModRefBS::PrecisionStyle precision,

                                       HeapWord* boundary) {

   return new FreeListSpace_DCTOC(this, _collector, cl, precision, boundary);

 }

 // Note on locking for the space iteration functions:

 // since the collector's iteration activities are concurrent with

 // allocation activities by mutators, absent a suitable mutual exclusion

 // mechanism the iterators may go awry. For instace a block being iterated

 // may suddenly be allocated or divided up and part of it allocated and

 // so on.

 // Apply the given closure to each block in the space.

 void CompactibleFreeListSpace::blk_iterate_careful(BlkClosureCareful* cl) {

   assert_lock_strong(freelistLock());

   HeapWord *cur, *limit;

   for (cur = bottom(), limit = end(); cur < limit;

        cur += cl->do_blk_careful(cur));

 }

 // Apply the given closure to each block in the space.

 void CompactibleFreeListSpace::blk_iterate(BlkClosure* cl) {

   assert_lock_strong(freelistLock());

   HeapWord *cur, *limit;

   for (cur = bottom(), limit = end(); cur < limit;

        cur += cl->do_blk(cur));

 }

 // Apply the given closure to each oop in the space.

 void CompactibleFreeListSpace::oop_iterate(ExtendedOopClosure* cl) {

   assert_lock_strong(freelistLock());

   HeapWord *cur, *limit;

   size_t curSize;

   for (cur = bottom(), limit = end(); cur < limit;

        cur += curSize) {

     curSize = block_size(cur);

     if (block_is_obj(cur)) {

       oop(cur)->oop_iterate(cl);

     }

   }

 }

 // Apply the given closure to each oop in the space \intersect memory region.

 void CompactibleFreeListSpace::oop_iterate(MemRegion mr, ExtendedOopClosure* cl) {

   assert_lock_strong(freelistLock());

   if (is_empty()) {

     return;

   }

   MemRegion cur = MemRegion(bottom(), end());

   mr = mr.intersection(cur);

   if (mr.is_empty()) {

     return;

   }

   if (mr.equals(cur)) {

     oop_iterate(cl);

     return;

   }

   assert(mr.end() <= end(), "just took an intersection above");

   HeapWord* obj_addr = block_start(mr.start());

   HeapWord* t = mr.end();

   SpaceMemRegionOopsIterClosure smr_blk(cl, mr);

   if (block_is_obj(obj_addr)) {

     // Handle first object specially.

     oop obj = oop(obj_addr);

     obj_addr += adjustObjectSize(obj->oop_iterate(&smr_blk));

   } else {

     FreeChunk* fc = (FreeChunk*)obj_addr;

     obj_addr += fc->size();

   }

   while (obj_addr < t) {

     HeapWord* obj = obj_addr;

     obj_addr += block_size(obj_addr);

     // If "obj_addr" is not greater than top, then the

     // entire object "obj" is within the region.

     if (obj_addr <= t) {

       if (block_is_obj(obj)) {

         oop(obj)->oop_iterate(cl);

       }

     } else {

       // "obj" extends beyond end of region

       if (block_is_obj(obj)) {

         oop(obj)->oop_iterate(&smr_blk);

       }

       break;

     }

   }

 }

 // NOTE: In the following methods, in order to safely be able to

 // apply the closure to an object, we need to be sure that the

 // object has been initialized. We are guaranteed that an object

 // is initialized if we are holding the Heap_lock with the

 // world stopped.

 void CompactibleFreeListSpace::verify_objects_initialized() const {

   if (is_init_completed()) {

     assert_locked_or_safepoint(Heap_lock);

     if (Universe::is_fully_initialized()) {

       guarantee(SafepointSynchronize::is_at_safepoint(),

                 "Required for objects to be initialized");

     }

   } // else make a concession at vm start-up

 }

 // Apply the given closure to each object in the space

 void CompactibleFreeListSpace::object_iterate(ObjectClosure* blk) {

   assert_lock_strong(freelistLock());

   NOT_PRODUCT(verify_objects_initialized());

   HeapWord *cur, *limit;

   size_t curSize;

   for (cur = bottom(), limit = end(); cur < limit;

        cur += curSize) {

     curSize = block_size(cur);

     if (block_is_obj(cur)) {

       blk->do_object(oop(cur));

     }

   }

 }

 // Apply the given closure to each live object in the space

 //   The usage of CompactibleFreeListSpace

 // by the ConcurrentMarkSweepGeneration for concurrent GC's allows

 // objects in the space with references to objects that are no longer

 // valid.  For example, an object may reference another object

 // that has already been sweep up (collected).  This method uses

 // obj_is_alive() to determine whether it is safe to apply the closure to

 // an object.  See obj_is_alive() for details on how liveness of an

 // object is decided.

 void CompactibleFreeListSpace::safe_object_iterate(ObjectClosure* blk) {

   assert_lock_strong(freelistLock());

   NOT_PRODUCT(verify_objects_initialized());

   HeapWord *cur, *limit;

   size_t curSize;

   for (cur = bottom(), limit = end(); cur < limit;

        cur += curSize) {

     curSize = block_size(cur);

     if (block_is_obj(cur) && obj_is_alive(cur)) {

       blk->do_object(oop(cur));

     }

   }

 }

 void CompactibleFreeListSpace::object_iterate_mem(MemRegion mr,

                                                   UpwardsObjectClosure* cl) {

   assert_locked(freelistLock());

   NOT_PRODUCT(verify_objects_initialized());

   Space::object_iterate_mem(mr, cl);

 }

 // Callers of this iterator beware: The closure application should

 // be robust in the face of uninitialized objects and should (always)

 // return a correct size so that the next addr + size below gives us a

 // valid block boundary. [See for instance,

 // ScanMarkedObjectsAgainCarefullyClosure::do_object_careful()

 // in ConcurrentMarkSweepGeneration.cpp.]

 HeapWord*

 CompactibleFreeListSpace::object_iterate_careful(ObjectClosureCareful* cl) {

   assert_lock_strong(freelistLock());

   HeapWord *addr, *last;

   size_t size;

   for (addr = bottom(), last  = end();

        addr < last; addr += size) {

     FreeChunk* fc = (FreeChunk*)addr;

     if (fc->is_free()) {

       // Since we hold the free list lock, which protects direct

       // allocation in this generation by mutators, a free object

       // will remain free throughout this iteration code.

       size = fc->size();

     } else {

       // Note that the object need not necessarily be initialized,

       // because (for instance) the free list lock does NOT protect

       // object initialization. The closure application below must

       // therefore be correct in the face of uninitialized objects.

       size = cl->do_object_careful(oop(addr));

       if (size == 0) {

         // An unparsable object found. Signal early termination.

         return addr;

       }

     }

   }

   return NULL;

 }

 // Callers of this iterator beware: The closure application should

 // be robust in the face of uninitialized objects and should (always)

 // return a correct size so that the next addr + size below gives us a

 // valid block boundary. [See for instance,

 // ScanMarkedObjectsAgainCarefullyClosure::do_object_careful()

 // in ConcurrentMarkSweepGeneration.cpp.]

 HeapWord*

 CompactibleFreeListSpace::object_iterate_careful_m(MemRegion mr,

   ObjectClosureCareful* cl) {

   assert_lock_strong(freelistLock());

   // Can't use used_region() below because it may not necessarily

   // be the same as [bottom(),end()); although we could

   // use [used_region().start(),round_to(used_region().end(),CardSize)),

   // that appears too cumbersome, so we just do the simpler check

   // in the assertion below.

   assert(!mr.is_empty() && MemRegion(bottom(),end()).contains(mr),

          "mr should be non-empty and within used space");

   HeapWord *addr, *end;

   size_t size;

   for (addr = block_start_careful(mr.start()), end  = mr.end();

        addr < end; addr += size) {

     FreeChunk* fc = (FreeChunk*)addr;

     if (fc->is_free()) {

       // Since we hold the free list lock, which protects direct

       // allocation in this generation by mutators, a free object

       // will remain free throughout this iteration code.

       size = fc->size();

     } else {

       // Note that the object need not necessarily be initialized,

       // because (for instance) the free list lock does NOT protect

       // object initialization. The closure application below must

       // therefore be correct in the face of uninitialized objects.

       size = cl->do_object_careful_m(oop(addr), mr);

       if (size == 0) {

         // An unparsable object found. Signal early termination.

         return addr;

       }

     }

   }

   return NULL;

 }

 HeapWord* CompactibleFreeListSpace::block_start_const(const void* p) const {

   NOT_PRODUCT(verify_objects_initialized());

   return _bt.block_start(p);

 }

 HeapWord* CompactibleFreeListSpace::block_start_careful(const void* p) const {

   return _bt.block_start_careful(p);

 }

 size_t CompactibleFreeListSpace::block_size(const HeapWord* p) const {

   NOT_PRODUCT(verify_objects_initialized());

   // This must be volatile, or else there is a danger that the compiler

   // will compile the code below into a sometimes-infinite loop, by keeping

   // the value read the first time in a register.

   while (true) {

     // We must do this until we get a consistent view of the object.

     if (FreeChunk::indicatesFreeChunk(p)) {

       volatile FreeChunk* fc = (volatile FreeChunk*)p;

       size_t res = fc->size();

       // If the object is still a free chunk, return the size, else it

       // has been allocated so try again.

       if (FreeChunk::indicatesFreeChunk(p)) {

         assert(res != 0, "Block size should not be 0");

         return res;

       }

     } else {

       // must read from what 'p' points to in each loop.

       Klass* k = ((volatile oopDesc*)p)->klass_or_null();

       if (k != NULL) {

         assert(k->is_klass(), "Should really be klass oop.");

         oop o = (oop)p;

         assert(o->is_oop(true /* ignore mark word */), "Should be an oop.");

         size_t res = o->size_given_klass(k);

         res = adjustObjectSize(res);

         assert(res != 0, "Block size should not be 0");

         return res;

       }

     }

   }

 }

 // TODO: Now that is_parsable is gone, we should combine these two functions.

 // A variant of the above that uses the Printezis bits for

 // unparsable but allocated objects. This avoids any possible

 // stalls waiting for mutators to initialize objects, and is

 // thus potentially faster than the variant above. However,

 // this variant may return a zero size for a block that is

 // under mutation and for which a consistent size cannot be

 // inferred without stalling; see CMSCollector::block_size_if_printezis_bits().

 size_t CompactibleFreeListSpace::block_size_no_stall(HeapWord* p,

                                                      const CMSCollector* c)

 const {

   assert(MemRegion(bottom(), end()).contains(p), "p not in space");

   // This must be volatile, or else there is a danger that the compiler

   // will compile the code below into a sometimes-infinite loop, by keeping

   // the value read the first time in a register.

   DEBUG_ONLY(uint loops = 0;)

   while (true) {

     // We must do this until we get a consistent view of the object.

     if (FreeChunk::indicatesFreeChunk(p)) {

       volatile FreeChunk* fc = (volatile FreeChunk*)p;

       size_t res = fc->size();

       if (FreeChunk::indicatesFreeChunk(p)) {

         assert(res != 0, "Block size should not be 0");

         assert(loops == 0, "Should be 0");

         return res;

       }

     } else {

       // must read from what 'p' points to in each loop.

       Klass* k = ((volatile oopDesc*)p)->klass_or_null();

       // We trust the size of any object that has a non-NULL

       // klass and (for those in the perm gen) is parsable

       // -- irrespective of its conc_safe-ty.

       if (k != NULL) {

         assert(k->is_klass(), "Should really be klass oop.");

         oop o = (oop)p;

         assert(o->is_oop(), "Should be an oop");

         size_t res = o->size_given_klass(k);

         res = adjustObjectSize(res);

         assert(res != 0, "Block size should not be 0");

         return res;

       } else {

         // May return 0 if P-bits not present.

         return c->block_size_if_printezis_bits(p);

       }

     }

     assert(loops == 0, "Can loop at most once");

     DEBUG_ONLY(loops++;)

   }

 }

 size_t CompactibleFreeListSpace::block_size_nopar(const HeapWord* p) const {

   NOT_PRODUCT(verify_objects_initialized());

   assert(MemRegion(bottom(), end()).contains(p), "p not in space");

   FreeChunk* fc = (FreeChunk*)p;

   if (fc->is_free()) {

     return fc->size();

   } else {

     // Ignore mark word because this may be a recently promoted

     // object whose mark word is used to chain together grey

     // objects (the last one would have a null value).

     assert(oop(p)->is_oop(true), "Should be an oop");

     return adjustObjectSize(oop(p)->size());

   }

 }

 // This implementation assumes that the property of "being an object" is

 // stable.  But being a free chunk may not be (because of parallel

 // promotion.)

 bool CompactibleFreeListSpace::block_is_obj(const HeapWord* p) const {

   FreeChunk* fc = (FreeChunk*)p;

   assert(is_in_reserved(p), "Should be in space");

   // When doing a mark-sweep-compact of the CMS generation, this

   // assertion may fail because prepare_for_compaction() uses

   // space that is garbage to maintain information on ranges of

   // live objects so that these live ranges can be moved as a whole.

   // Comment out this assertion until that problem can be solved

   // (i.e., that the block start calculation may look at objects

   // at address below "p" in finding the object that contains "p"

   // and those objects (if garbage) may have been modified to hold

   // live range information.

   // assert(CollectedHeap::use_parallel_gc_threads() || _bt.block_start(p) == p,

   //        "Should be a block boundary");

   if (FreeChunk::indicatesFreeChunk(p)) return false;

   Klass* k = oop(p)->klass_or_null();

   if (k != NULL) {

     // Ignore mark word because it may have been used to

     // chain together promoted objects (the last one

     // would have a null value).

     assert(oop(p)->is_oop(true), "Should be an oop");

     return true;

   } else {

     return false;  // Was not an object at the start of collection.

   }

 }

 // Check if the object is alive. This fact is checked either by consulting

 // the main marking bitmap in the sweeping phase or, if it's a permanent

 // generation and we're not in the sweeping phase, by checking the

 // perm_gen_verify_bit_map where we store the "deadness" information if

 // we did not sweep the perm gen in the most recent previous GC cycle.

 bool CompactibleFreeListSpace::obj_is_alive(const HeapWord* p) const {

   assert(SafepointSynchronize::is_at_safepoint() || !is_init_completed(),

          "Else races are possible");

   assert(block_is_obj(p), "The address should point to an object");

   // If we're sweeping, we use object liveness information from the main bit map

   // for both perm gen and old gen.

   // We don't need to lock the bitmap (live_map or dead_map below), because

   // EITHER we are in the middle of the sweeping phase, and the

   // main marking bit map (live_map below) is locked,

   // OR we're in other phases and perm_gen_verify_bit_map (dead_map below)

   // is stable, because it's mutated only in the sweeping phase.

   // NOTE: This method is also used by jmap where, if class unloading is

   // off, the results can return "false" for legitimate perm objects,

   // when we are not in the midst of a sweeping phase, which can result

   // in jmap not reporting certain perm gen objects. This will be moot

   // if/when the perm gen goes away in the future.

   if (_collector->abstract_state() == CMSCollector::Sweeping) {

     CMSBitMap* live_map = _collector->markBitMap();

     return live_map->par_isMarked((HeapWord*) p);

   }

   return true;

 }

 bool CompactibleFreeListSpace::block_is_obj_nopar(const HeapWord* p) const {

   FreeChunk* fc = (FreeChunk*)p;

   assert(is_in_reserved(p), "Should be in space");

   assert(_bt.block_start(p) == p, "Should be a block boundary");

   if (!fc->is_free()) {

     // Ignore mark word because it may have been used to

     // chain together promoted objects (the last one

     // would have a null value).

     assert(oop(p)->is_oop(true), "Should be an oop");

     return true;

   }

   return false;

 }

 // "MT-safe but not guaranteed MT-precise" (TM); you may get an

 // approximate answer if you don't hold the freelistlock when you call this.

 size_t CompactibleFreeListSpace::totalSizeInIndexedFreeLists() const {

   size_t size = 0;

   for (size_t i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) {

     debug_only(

       // We may be calling here without the lock in which case we

       // won't do this modest sanity check.

       if (freelistLock()->owned_by_self()) {

         size_t total_list_size = 0;

         for (FreeChunk* fc = _indexedFreeList[i].head(); fc != NULL;

           fc = fc->next()) {

           total_list_size += i;

         }

         assert(total_list_size == i * _indexedFreeList[i].count(),

                "Count in list is incorrect");

       }

     )

     size += i * _indexedFreeList[i].count();

   }

   return size;

 }

 HeapWord* CompactibleFreeListSpace::par_allocate(size_t size) {

   MutexLockerEx x(freelistLock(), Mutex::_no_safepoint_check_flag);

   return allocate(size);

 }

 HeapWord*

 CompactibleFreeListSpace::getChunkFromSmallLinearAllocBlockRemainder(size_t size) {

   return getChunkFromLinearAllocBlockRemainder(&_smallLinearAllocBlock, size);

 }

 HeapWord* CompactibleFreeListSpace::allocate(size_t size) {

   assert_lock_strong(freelistLock());

   HeapWord* res = NULL;

   assert(size == adjustObjectSize(size),

          "use adjustObjectSize() before calling into allocate()");

   if (_adaptive_freelists) {

     res = allocate_adaptive_freelists(size);

   } else {  // non-adaptive free lists

     res = allocate_non_adaptive_freelists(size);

   }

   if (res != NULL) {

     // check that res does lie in this space!

     assert(is_in_reserved(res), "Not in this space!");

     assert(is_aligned((void*)res), "alignment check");

     FreeChunk* fc = (FreeChunk*)res;

     fc->markNotFree();

     assert(!fc->is_free(), "shouldn't be marked free");

     assert(oop(fc)->klass_or_null() == NULL, "should look uninitialized");

     // Verify that the block offset table shows this to

     // be a single block, but not one which is unallocated.

     _bt.verify_single_block(res, size);

     _bt.verify_not_unallocated(res, size);

     // mangle a just allocated object with a distinct pattern.

     debug_only(fc->mangleAllocated(size));

   }

   return res;

 }

 HeapWord* CompactibleFreeListSpace::allocate_non_adaptive_freelists(size_t size) {

   HeapWord* res = NULL;

   // try and use linear allocation for smaller blocks

   if (size < _smallLinearAllocBlock._allocation_size_limit) {

     // if successful, the following also adjusts block offset table

     res = getChunkFromSmallLinearAllocBlock(size);

   }

   // Else triage to indexed lists for smaller sizes

   if (res == NULL) {

     if (size < SmallForDictionary) {

       res = (HeapWord*) getChunkFromIndexedFreeList(size);

     } else {

       // else get it from the big dictionary; if even this doesn't

       // work we are out of luck.

       res = (HeapWord*)getChunkFromDictionaryExact(size);

     }

   }

   return res;

 }

 HeapWord* CompactibleFreeListSpace::allocate_adaptive_freelists(size_t size) {

   assert_lock_strong(freelistLock());

   HeapWord* res = NULL;

   assert(size == adjustObjectSize(size),

          "use adjustObjectSize() before calling into allocate()");

   // Strategy

   //   if small

   //     exact size from small object indexed list if small

   //     small or large linear allocation block (linAB) as appropriate

   //     take from lists of greater sized chunks

   //   else

   //     dictionary

   //     small or large linear allocation block if it has the space

   // Try allocating exact size from indexTable first

   if (size < IndexSetSize) {

     res = (HeapWord*) getChunkFromIndexedFreeList(size);

     if(res != NULL) {

       assert(res != (HeapWord*)_indexedFreeList[size].head(),

         "Not removed from free list");

       // no block offset table adjustment is necessary on blocks in

       // the indexed lists.

     // Try allocating from the small LinAB

     } else if (size < _smallLinearAllocBlock._allocation_size_limit &&

         (res = getChunkFromSmallLinearAllocBlock(size)) != NULL) {

         // if successful, the above also adjusts block offset table

         // Note that this call will refill the LinAB to

         // satisfy the request.  This is different that

         // evm.

         // Don't record chunk off a LinAB?  smallSplitBirth(size);

     } else {

       // Raid the exact free lists larger than size, even if they are not

       // overpopulated.

       res = (HeapWord*) getChunkFromGreater(size);

     }

   } else {

     // Big objects get allocated directly from the dictionary.

     res = (HeapWord*) getChunkFromDictionaryExact(size);

     if (res == NULL) {

       // Try hard not to fail since an allocation failure will likely

       // trigger a synchronous GC.  Try to get the space from the

       // allocation blocks.

       res = getChunkFromSmallLinearAllocBlockRemainder(size);

     }

   }

   return res;

 }

 // A worst-case estimate of the space required (in HeapWords) to expand the heap

 // when promoting obj.

 size_t CompactibleFreeListSpace::expansionSpaceRequired(size_t obj_size) const {

   // Depending on the object size, expansion may require refilling either a

   // bigLAB or a smallLAB plus refilling a PromotionInfo object.  MinChunkSize

   // is added because the dictionary may over-allocate to avoid fragmentation.

   size_t space = obj_size;

   if (!_adaptive_freelists) {

     space = MAX2(space, _smallLinearAllocBlock._refillSize);

   }

   space += _promoInfo.refillSize() + 2 * MinChunkSize;

   return space;

 }

 FreeChunk* CompactibleFreeListSpace::getChunkFromGreater(size_t numWords) {

   FreeChunk* ret;

   assert(numWords >= MinChunkSize, "Size is less than minimum");

   assert(linearAllocationWouldFail() || bestFitFirst(),

     "Should not be here");

   size_t i;

   size_t currSize = numWords + MinChunkSize;

   assert(currSize % MinObjAlignment == 0, "currSize should be aligned");

   for (i = currSize; i < IndexSetSize; i += IndexSetStride) {

     AdaptiveFreeList<FreeChunk>* fl = &_indexedFreeList[i];

     if (fl->head()) {

       ret = getFromListGreater(fl, numWords);

       assert(ret == NULL || ret->is_free(), "Should be returning a free chunk");

       return ret;

     }

   }

   currSize = MAX2((size_t)SmallForDictionary,

                   (size_t)(numWords + MinChunkSize));

   /* Try to get a chunk that satisfies request, while avoiding

      fragmentation that can't be handled. */

   {

     ret =  dictionary()->get_chunk(currSize);

     if (ret != NULL) {

       assert(ret->size() - numWords >= MinChunkSize,

              "Chunk is too small");

       _bt.allocated((HeapWord*)ret, ret->size());

       /* Carve returned chunk. */

       (void) splitChunkAndReturnRemainder(ret, numWords);

       /* Label this as no longer a free chunk. */

       assert(ret->is_free(), "This chunk should be free");

       ret->link_prev(NULL);

     }

     assert(ret == NULL || ret->is_free(), "Should be returning a free chunk");

     return ret;

   }

   ShouldNotReachHere();

 }

 bool CompactibleFreeListSpace::verifyChunkInIndexedFreeLists(FreeChunk* fc) const {

   assert(fc->size() < IndexSetSize, "Size of chunk is too large");

   return _indexedFreeList[fc->size()].verify_chunk_in_free_list(fc);

 }

 bool CompactibleFreeListSpace::verify_chunk_is_linear_alloc_block(FreeChunk* fc) const {

   assert((_smallLinearAllocBlock._ptr != (HeapWord*)fc) ||

          (_smallLinearAllocBlock._word_size == fc->size()),

          "Linear allocation block shows incorrect size");

   return ((_smallLinearAllocBlock._ptr == (HeapWord*)fc) &&

           (_smallLinearAllocBlock._word_size == fc->size()));

 }

 // Check if the purported free chunk is present either as a linear

 // allocation block, the size-indexed table of (smaller) free blocks,

 // or the larger free blocks kept in the binary tree dictionary.

 bool CompactibleFreeListSpace::verify_chunk_in_free_list(FreeChunk* fc) const {

   if (verify_chunk_is_linear_alloc_block(fc)) {

     return true;

   } else if (fc->size() < IndexSetSize) {

     return verifyChunkInIndexedFreeLists(fc);

   } else {

     return dictionary()->verify_chunk_in_free_list(fc);

   }

 }

 #ifndef PRODUCT

 void CompactibleFreeListSpace::assert_locked() const {

   CMSLockVerifier::assert_locked(freelistLock(), parDictionaryAllocLock());

 }

 void CompactibleFreeListSpace::assert_locked(const Mutex* lock) const {

   CMSLockVerifier::assert_locked(lock);

 }

 #endif

 FreeChunk* CompactibleFreeListSpace::allocateScratch(size_t size) {

   // In the parallel case, the main thread holds the free list lock

   // on behalf the parallel threads.

   FreeChunk* fc;

   {

     // If GC is parallel, this might be called by several threads.

     // This should be rare enough that the locking overhead won't affect

     // the sequential code.

     MutexLockerEx x(parDictionaryAllocLock(),

                     Mutex::_no_safepoint_check_flag);

     fc = getChunkFromDictionary(size);

   }

   if (fc != NULL) {

     fc->dontCoalesce();

     assert(fc->is_free(), "Should be free, but not coalescable");

     // Verify that the block offset table shows this to

     // be a single block, but not one which is unallocated.

     _bt.verify_single_block((HeapWord*)fc, fc->size());

     _bt.verify_not_unallocated((HeapWord*)fc, fc->size());

   }

   return fc;

 }

 oop CompactibleFreeListSpace::promote(oop obj, size_t obj_size) {

   assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");

   assert_locked();

   // if we are tracking promotions, then first ensure space for

   // promotion (including spooling space for saving header if necessary).

   // then allocate and copy, then track promoted info if needed.

   // When tracking (see PromotionInfo::track()), the mark word may

   // be displaced and in this case restoration of the mark word

   // occurs in the (oop_since_save_marks_)iterate phase.

   if (_promoInfo.tracking() && !_promoInfo.ensure_spooling_space()) {

     return NULL;

   }

   // Call the allocate(size_t, bool) form directly to avoid the

   // additional call through the allocate(size_t) form.  Having

   // the compile inline the call is problematic because allocate(size_t)

   // is a virtual method.

   HeapWord* res = allocate(adjustObjectSize(obj_size));

   if (res != NULL) {

     Copy::aligned_disjoint_words((HeapWord*)obj, res, obj_size);

     // if we should be tracking promotions, do so.

     if (_promoInfo.tracking()) {

         _promoInfo.track((PromotedObject*)res);

     }

   }

   return oop(res);

 }

 HeapWord*

 CompactibleFreeListSpace::getChunkFromSmallLinearAllocBlock(size_t size) {

   assert_locked();

   assert(size >= MinChunkSize, "minimum chunk size");

   assert(size <  _smallLinearAllocBlock._allocation_size_limit,

     "maximum from smallLinearAllocBlock");

   return getChunkFromLinearAllocBlock(&_smallLinearAllocBlock, size);

 }

 HeapWord*

 CompactibleFreeListSpace::getChunkFromLinearAllocBlock(LinearAllocBlock *blk,

                                                        size_t size) {

   assert_locked();

   assert(size >= MinChunkSize, "too small");

   HeapWord* res = NULL;

   // Try to do linear allocation from blk, making sure that

   if (blk->_word_size == 0) {

     // We have probably been unable to fill this either in the prologue or

     // when it was exhausted at the last linear allocation. Bail out until

     // next time.

     assert(blk->_ptr == NULL, "consistency check");

     return NULL;

   }

   assert(blk->_word_size != 0 && blk->_ptr != NULL, "consistency check");

   res = getChunkFromLinearAllocBlockRemainder(blk, size);

   if (res != NULL) return res;

   // about to exhaust this linear allocation block

   if (blk->_word_size == size) { // exactly satisfied

     res = blk->_ptr;

     _bt.allocated(res, blk->_word_size);

   } else if (size + MinChunkSize <= blk->_refillSize) {

     size_t sz = blk->_word_size;

     // Update _unallocated_block if the size is such that chunk would be

     // returned to the indexed free list.  All other chunks in the indexed

     // free lists are allocated from the dictionary so that _unallocated_block

     // has already been adjusted for them.  Do it here so that the cost

     // for all chunks added back to the indexed free lists.

     if (sz < SmallForDictionary) {

       _bt.allocated(blk->_ptr, sz);

     }

     // Return the chunk that isn't big enough, and then refill below.

     addChunkToFreeLists(blk->_ptr, sz);

     split_birth(sz);

     // Don't keep statistics on adding back chunk from a LinAB.

   } else {

     // A refilled block would not satisfy the request.

     return NULL;

   }

   blk->_ptr = NULL; blk->_word_size = 0;

   refillLinearAllocBlock(blk);

   assert(blk->_ptr == NULL || blk->_word_size >= size + MinChunkSize,

          "block was replenished");

   if (res != NULL) {

     split_birth(size);

     repairLinearAllocBlock(blk);

   } else if (blk->_ptr != NULL) {

     res = blk->_ptr;

     size_t blk_size = blk->_word_size;

     blk->_word_size -= size;

     blk->_ptr  += size;

     split_birth(size);

     repairLinearAllocBlock(blk);

     // Update BOT last so that other (parallel) GC threads see a consistent

     // view of the BOT and free blocks.

     // Above must occur before BOT is updated below.

     OrderAccess::storestore();

     _bt.split_block(res, blk_size, size);  // adjust block offset table

   }

   return res;

 }

 HeapWord*  CompactibleFreeListSpace::getChunkFromLinearAllocBlockRemainder(

                                         LinearAllocBlock* blk,

                                         size_t size) {

   assert_locked();

   assert(size >= MinChunkSize, "too small");

   HeapWord* res = NULL;

   // This is the common case.  Keep it simple.

   if (blk->_word_size >= size + MinChunkSize) {

     assert(blk->_ptr != NULL, "consistency check");

     res = blk->_ptr;

     // Note that the BOT is up-to-date for the linAB before allocation.  It

     // indicates the start of the linAB.  The split_block() updates the

     // BOT for the linAB after the allocation (indicates the start of the

     // next chunk to be allocated).

     size_t blk_size = blk->_word_size;

     blk->_word_size -= size;

     blk->_ptr  += size;

     split_birth(size);

     repairLinearAllocBlock(blk);

     // Update BOT last so that other (parallel) GC threads see a consistent

     // view of the BOT and free blocks.

     // Above must occur before BOT is updated below.

     OrderAccess::storestore();

     _bt.split_block(res, blk_size, size);  // adjust block offset table

     _bt.allocated(res, size);

   }

   return res;

 }

 FreeChunk*

 CompactibleFreeListSpace::getChunkFromIndexedFreeList(size_t size) {

   assert_locked();

   assert(size < SmallForDictionary, "just checking");

   FreeChunk* res;

   res = _indexedFreeList[size].get_chunk_at_head();

   if (res == NULL) {

     res = getChunkFromIndexedFreeListHelper(size);

   }

   _bt.verify_not_unallocated((HeapWord*) res, size);

   assert(res == NULL || res->size() == size, "Incorrect block size");

   return res;

 }

 FreeChunk*

 CompactibleFreeListSpace::getChunkFromIndexedFreeListHelper(size_t size,

   bool replenish) {

   assert_locked();

   FreeChunk* fc = NULL;

   if (size < SmallForDictionary) {

     assert(_indexedFreeList[size].head() == NULL ||

       _indexedFreeList[size].surplus() <= 0,

       "List for this size should be empty or under populated");

     // Try best fit in exact lists before replenishing the list

     if (!bestFitFirst() || (fc = bestFitSmall(size)) == NULL) {

       // Replenish list.

       //

       // Things tried that failed.

       //   Tried allocating out of the two LinAB's first before

       // replenishing lists.

       //   Tried small linAB of size 256 (size in indexed list)

       // and replenishing indexed lists from the small linAB.

       //

       FreeChunk* newFc = NULL;

       const size_t replenish_size = CMSIndexedFreeListReplenish * size;

       if (replenish_size < SmallForDictionary) {

         // Do not replenish from an underpopulated size.

         if (_indexedFreeList[replenish_size].surplus() > 0 &&

             _indexedFreeList[replenish_size].head() != NULL) {

           newFc = _indexedFreeList[replenish_size].get_chunk_at_head();

         } else if (bestFitFirst()) {

           newFc = bestFitSmall(replenish_size);

         }

       }

       if (newFc == NULL && replenish_size > size) {

         assert(CMSIndexedFreeListReplenish > 1, "ctl pt invariant");

         newFc = getChunkFromIndexedFreeListHelper(replenish_size, false);

       }

       // Note: The stats update re split-death of block obtained above

       // will be recorded below precisely when we know we are going to

       // be actually splitting it into more than one pieces below.

       if (newFc != NULL) {

         if  (replenish || CMSReplenishIntermediate) {

           // Replenish this list and return one block to caller.

           size_t i;

           FreeChunk *curFc, *nextFc;

           size_t num_blk = newFc->size() / size;

           assert(num_blk >= 1, "Smaller than requested?");

           assert(newFc->size() % size == 0, "Should be integral multiple of request");

           if (num_blk > 1) {

             // we are sure we will be splitting the block just obtained

             // into multiple pieces; record the split-death of the original

             splitDeath(replenish_size);

           }

           // carve up and link blocks 0, ..., num_blk - 2

           // The last chunk is not added to the lists but is returned as the

           // free chunk.

           for (curFc = newFc, nextFc = (FreeChunk*)((HeapWord*)curFc + size),

                i = 0;

                i < (num_blk - 1);

                curFc = nextFc, nextFc = (FreeChunk*)((HeapWord*)nextFc + size),

                i++) {

             curFc->set_size(size);

             // Don't record this as a return in order to try and

             // determine the "returns" from a GC.

             _bt.verify_not_unallocated((HeapWord*) fc, size);

             _indexedFreeList[size].return_chunk_at_tail(curFc, false);

             _bt.mark_block((HeapWord*)curFc, size);

             split_birth(size);

             // Don't record the initial population of the indexed list

             // as a split birth.

           }

           // check that the arithmetic was OK above

           assert((HeapWord*)nextFc == (HeapWord*)newFc + num_blk*size,

             "inconsistency in carving newFc");

           curFc->set_size(size);

           _bt.mark_block((HeapWord*)curFc, size);

           split_birth(size);

           fc = curFc;

         } else {

           // Return entire block to caller

           fc = newFc;

         }

       }

     }

   } else {

     // Get a free chunk from the free chunk dictionary to be returned to

     // replenish the indexed free list.

     fc = getChunkFromDictionaryExact(size);

   }

   // assert(fc == NULL || fc->is_free(), "Should be returning a free chunk");

   return fc;

 }

 FreeChunk*

 CompactibleFreeListSpace::getChunkFromDictionary(size_t size) {

   assert_locked();

   FreeChunk* fc = _dictionary->get_chunk(size);

   if (fc == NULL) {

     return NULL;

   }

   _bt.allocated((HeapWord*)fc, fc->size());

   if (fc->size() >= size + MinChunkSize) {

     fc = splitChunkAndReturnRemainder(fc, size);

   }

   assert(fc->size() >= size, "chunk too small");

   assert(fc->size() < size + MinChunkSize, "chunk too big");

   _bt.verify_single_block((HeapWord*)fc, fc->size());

   return fc;

 }

 FreeChunk*

 CompactibleFreeListSpace::getChunkFromDictionaryExact(size_t size) {

   assert_locked();

   FreeChunk* fc = _dictionary->get_chunk(size);

   if (fc == NULL) {

     return fc;

   }

   _bt.allocated((HeapWord*)fc, fc->size());

   if (fc->size() == size) {

     _bt.verify_single_block((HeapWord*)fc, size);

     return fc;

   }

   assert(fc->size() > size, "get_chunk() guarantee");

   if (fc->size() < size + MinChunkSize) {

     // Return the chunk to the dictionary and go get a bigger one.

     returnChunkToDictionary(fc);

     fc = _dictionary->get_chunk(size + MinChunkSize);

     if (fc == NULL) {

       return NULL;

     }

     _bt.allocated((HeapWord*)fc, fc->size());

   }

   assert(fc->size() >= size + MinChunkSize, "tautology");

   fc = splitChunkAndReturnRemainder(fc, size);

   assert(fc->size() == size, "chunk is wrong size");

   _bt.verify_single_block((HeapWord*)fc, size);

   return fc;

 }

 void

 CompactibleFreeListSpace::returnChunkToDictionary(FreeChunk* chunk) {

   assert_locked();

   size_t size = chunk->size();

   _bt.verify_single_block((HeapWord*)chunk, size);

   // adjust _unallocated_block downward, as necessary

   _bt.freed((HeapWord*)chunk, size);

   _dictionary->return_chunk(chunk);

 #ifndef PRODUCT

   if (CMSCollector::abstract_state() != CMSCollector::Sweeping) {

     TreeChunk<FreeChunk, AdaptiveFreeList>* tc = TreeChunk<FreeChunk, AdaptiveFreeList>::as_TreeChunk(chunk);

     TreeList<FreeChunk, AdaptiveFreeList>* tl = tc->list();

     tl->verify_stats();

   }

 #endif // PRODUCT

 }

 void

 CompactibleFreeListSpace::returnChunkToFreeList(FreeChunk* fc) {

   assert_locked();

   size_t size = fc->size();

   _bt.verify_single_block((HeapWord*) fc, size);

   _bt.verify_not_unallocated((HeapWord*) fc, size);

   if (_adaptive_freelists) {

     _indexedFreeList[size].return_chunk_at_tail(fc);

   } else {

     _indexedFreeList[size].return_chunk_at_head(fc);

   }

 #ifndef PRODUCT

   if (CMSCollector::abstract_state() != CMSCollector::Sweeping) {

      _indexedFreeList[size].verify_stats();

   }

 #endif // PRODUCT

 }

 // Add chunk to end of last block -- if it's the largest

 // block -- and update BOT and census data. We would

 // of course have preferred to coalesce it with the

 // last block, but it's currently less expensive to find the

 // largest block than it is to find the last.

 void

 CompactibleFreeListSpace::addChunkToFreeListsAtEndRecordingStats(

   HeapWord* chunk, size_t     size) {

   // check that the chunk does lie in this space!

   assert(chunk != NULL && is_in_reserved(chunk), "Not in this space!");

   // One of the parallel gc task threads may be here

   // whilst others are allocating.

   Mutex* lock = NULL;

   if (ParallelGCThreads != 0) {

     lock = &_parDictionaryAllocLock;

   }

   FreeChunk* ec;

   {

     MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);

     ec = dictionary()->find_largest_dict();  // get largest block

     if (ec != NULL && ec->end() == (uintptr_t*) chunk) {

       // It's a coterminal block - we can coalesce.

       size_t old_size = ec->size();

       coalDeath(old_size);

       removeChunkFromDictionary(ec);

       size += old_size;

     } else {

       ec = (FreeChunk*)chunk;

     }

   }

   ec->set_size(size);

   debug_only(ec->mangleFreed(size));

   if (size < SmallForDictionary) {

     lock = _indexedFreeListParLocks[size];

   }

   MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);

   addChunkAndRepairOffsetTable((HeapWord*)ec, size, true);

   // record the birth under the lock since the recording involves

   // manipulation of the list on which the chunk lives and

   // if the chunk is allocated and is the last on the list,

   // the list can go away.

   coalBirth(size);

 }

 void

 CompactibleFreeListSpace::addChunkToFreeLists(HeapWord* chunk,

                                               size_t     size) {

   // check that the chunk does lie in this space!

   assert(chunk != NULL && is_in_reserved(chunk), "Not in this space!");

   assert_locked();

   _bt.verify_single_block(chunk, size);

   FreeChunk* fc = (FreeChunk*) chunk;

   fc->set_size(size);

   debug_only(fc->mangleFreed(size));

   if (size < SmallForDictionary) {

     returnChunkToFreeList(fc);

   } else {

     returnChunkToDictionary(fc);

   }

 }

 void

 CompactibleFreeListSpace::addChunkAndRepairOffsetTable(HeapWord* chunk,

   size_t size, bool coalesced) {

   assert_locked();

   assert(chunk != NULL, "null chunk");

   if (coalesced) {

     // repair BOT

     _bt.single_block(chunk, size);

   }

   addChunkToFreeLists(chunk, size);

 }

 // We _must_ find the purported chunk on our free lists;

 // we assert if we don't.

 void

 CompactibleFreeListSpace::removeFreeChunkFromFreeLists(FreeChunk* fc) {

   size_t size = fc->size();

   assert_locked();

   debug_only(verifyFreeLists());

   if (size < SmallForDictionary) {

     removeChunkFromIndexedFreeList(fc);

   } else {

     removeChunkFromDictionary(fc);

   }

   _bt.verify_single_block((HeapWord*)fc, size);

   debug_only(verifyFreeLists());

 }

 void

 CompactibleFreeListSpace::removeChunkFromDictionary(FreeChunk* fc) {

   size_t size = fc->size();

   assert_locked();

   assert(fc != NULL, "null chunk");

   _bt.verify_single_block((HeapWord*)fc, size);

   _dictionary->remove_chunk(fc);

   // adjust _unallocated_block upward, as necessary

   _bt.allocated((HeapWord*)fc, size);

 }

 void

 CompactibleFreeListSpace::removeChunkFromIndexedFreeList(FreeChunk* fc) {

   assert_locked();

   size_t size = fc->size();

   _bt.verify_single_block((HeapWord*)fc, size);

   NOT_PRODUCT(

     if (FLSVerifyIndexTable) {

       verifyIndexedFreeList(size);

     }

   )

   _indexedFreeList[size].remove_chunk(fc);

   NOT_PRODUCT(

     if (FLSVerifyIndexTable) {

       verifyIndexedFreeList(size);

     }

   )

 }

 FreeChunk* CompactibleFreeListSpace::bestFitSmall(size_t numWords) {

   /* A hint is the next larger size that has a surplus.

      Start search at a size large enough to guarantee that

      the excess is >= MIN_CHUNK. */

   size_t start = align_object_size(numWords + MinChunkSize);

   if (start < IndexSetSize) {

     AdaptiveFreeList<FreeChunk>* it   = _indexedFreeList;

     size_t    hint = _indexedFreeList[start].hint();

     while (hint < IndexSetSize) {

       assert(hint % MinObjAlignment == 0, "hint should be aligned");

       AdaptiveFreeList<FreeChunk> *fl = &_indexedFreeList[hint];

       if (fl->surplus() > 0 && fl->head() != NULL) {

         // Found a list with surplus, reset original hint

         // and split out a free chunk which is returned.

         _indexedFreeList[start].set_hint(hint);

         FreeChunk* res = getFromListGreater(fl, numWords);

         assert(res == NULL || res->is_free(),

           "Should be returning a free chunk");

         return res;

       }

       hint = fl->hint(); /* keep looking */

     }

     /* None found. */

     it[start].set_hint(IndexSetSize);

   }

   return NULL;

 }

 /* Requires fl->size >= numWords + MinChunkSize */

 FreeChunk* CompactibleFreeListSpace::getFromListGreater(AdaptiveFreeList<FreeChunk>* fl,

   size_t numWords) {

   FreeChunk *curr = fl->head();

   size_t oldNumWords = curr->size();

   assert(numWords >= MinChunkSize, "Word size is too small");

   assert(curr != NULL, "List is empty");

   assert(oldNumWords >= numWords + MinChunkSize,

         "Size of chunks in the list is too small");

   fl->remove_chunk(curr);

   // recorded indirectly by splitChunkAndReturnRemainder -

   // smallSplit(oldNumWords, numWords);

   FreeChunk* new_chunk = splitChunkAndReturnRemainder(curr, numWords);

   // Does anything have to be done for the remainder in terms of

   // fixing the card table?

   assert(new_chunk == NULL || new_chunk->is_free(),

     "Should be returning a free chunk");

   return new_chunk;

 }

 FreeChunk*

 CompactibleFreeListSpace::splitChunkAndReturnRemainder(FreeChunk* chunk,

   size_t new_size) {

   assert_locked();

   size_t size = chunk->size();

   assert(size > new_size, "Split from a smaller block?");

   assert(is_aligned(chunk), "alignment problem");

   assert(size == adjustObjectSize(size), "alignment problem");

   size_t rem_size = size - new_size;

   assert(rem_size == adjustObjectSize(rem_size), "alignment problem");

   assert(rem_size >= MinChunkSize, "Free chunk smaller than minimum");

   FreeChunk* ffc = (FreeChunk*)((HeapWord*)chunk + new_size);

   assert(is_aligned(ffc), "alignment problem");

   ffc->set_size(rem_size);

   ffc->link_next(NULL);

   ffc->link_prev(NULL); // Mark as a free block for other (parallel) GC threads.

   // Above must occur before BOT is updated below.

   // adjust block offset table

   OrderAccess::storestore();

   assert(chunk->is_free() && ffc->is_free(), "Error");

   _bt.split_block((HeapWord*)chunk, chunk->size(), new_size);

   if (rem_size < SmallForDictionary) {

     bool is_par = (SharedHeap::heap()->n_par_threads() > 0);

     if (is_par) _indexedFreeListParLocks[rem_size]->lock();

     assert(!is_par ||

            (SharedHeap::heap()->n_par_threads() ==

             SharedHeap::heap()->workers()->active_workers()), "Mismatch");

     returnChunkToFreeList(ffc);

     split(size, rem_size);

     if (is_par) _indexedFreeListParLocks[rem_size]->unlock();

   } else {

     returnChunkToDictionary(ffc);

     split(size ,rem_size);

   }

   chunk->set_size(new_size);

   return chunk;

 }

 void

 CompactibleFreeListSpace::sweep_completed() {

   // Now that space is probably plentiful, refill linear

   // allocation blocks as needed.

   refillLinearAllocBlocksIfNeeded();

 }

 void

 CompactibleFreeListSpace::gc_prologue() {

   assert_locked();

   if (PrintFLSStatistics != 0) {

     gclog_or_tty->print("Before GC:\n");

     reportFreeListStatistics();

   }

   refillLinearAllocBlocksIfNeeded();

 }

 void

 CompactibleFreeListSpace::gc_epilogue() {

   assert_locked();

   if (PrintGCDetails && Verbose && !_adaptive_freelists) {

     if (_smallLinearAllocBlock._word_size == 0)

       warning("CompactibleFreeListSpace(epilogue):: Linear allocation failure");

   }

   assert(_promoInfo.noPromotions(), "_promoInfo inconsistency");

   _promoInfo.stopTrackingPromotions();

   repairLinearAllocationBlocks();

   // Print Space's stats

   if (PrintFLSStatistics != 0) {

     gclog_or_tty->print("After GC:\n");

     reportFreeListStatistics();

   }

 }

 // Iteration support, mostly delegated from a CMS generation

 void CompactibleFreeListSpace::save_marks() {

   assert(Thread::current()->is_VM_thread(),

          "Global variable should only be set when single-threaded");

   // Mark the "end" of the used space at the time of this call;

   // note, however, that promoted objects from this point

   // on are tracked in the _promoInfo below.

   set_saved_mark_word(unallocated_block());

 #ifdef ASSERT

   // Check the sanity of save_marks() etc.

   MemRegion ur    = used_region();

   MemRegion urasm = used_region_at_save_marks();

   assert(ur.contains(urasm),

          err_msg(" Error at save_marks(): [" PTR_FORMAT "," PTR_FORMAT ")"

                  " should contain [" PTR_FORMAT "," PTR_FORMAT ")",

                  ur.start(), ur.end(), urasm.start(), urasm.end()));

 #endif

   // inform allocator that promotions should be tracked.

   assert(_promoInfo.noPromotions(), "_promoInfo inconsistency");

   _promoInfo.startTrackingPromotions();

 }

 bool CompactibleFreeListSpace::no_allocs_since_save_marks() {

   assert(_promoInfo.tracking(), "No preceding save_marks?");

   assert(SharedHeap::heap()->n_par_threads() == 0,

          "Shouldn't be called if using parallel gc.");

   return _promoInfo.noPromotions();

 }

 #define CFLS_OOP_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix)           \

                                                                             \

 void CompactibleFreeListSpace::                                             \

 oop_since_save_marks_iterate##nv_suffix(OopClosureType* blk) {              \

   assert(SharedHeap::heap()->n_par_threads() == 0,                          \

          "Shouldn't be called (yet) during parallel part of gc.");          \

   _promoInfo.promoted_oops_iterate##nv_suffix(blk);                         \

   /*                                                                        \

    * This also restores any displaced headers and removes the elements from \

    * the iteration set as they are processed, so that we have a clean slate \

    * at the end of the iteration. Note, thus, that if new objects are       \

    * promoted as a result of the iteration they are iterated over as well.  \

    */                                                                       \

   assert(_promoInfo.noPromotions(), "_promoInfo inconsistency");            \

 }

 ALL_SINCE_SAVE_MARKS_CLOSURES(CFLS_OOP_SINCE_SAVE_MARKS_DEFN)

 void CompactibleFreeListSpace::object_iterate_since_last_GC(ObjectClosure* cl) {

   // ugghh... how would one do this efficiently for a non-contiguous space?

   guarantee(false, "NYI");

 }

 bool CompactibleFreeListSpace::linearAllocationWouldFail() const {

   return _smallLinearAllocBlock._word_size == 0;

 }

 void CompactibleFreeListSpace::repairLinearAllocationBlocks() {

   // Fix up linear allocation blocks to look like free blocks

   repairLinearAllocBlock(&_smallLinearAllocBlock);

 }

 void CompactibleFreeListSpace::repairLinearAllocBlock(LinearAllocBlock* blk) {

   assert_locked();

   if (blk->_ptr != NULL) {

     assert(blk->_word_size != 0 && blk->_word_size >= MinChunkSize,

            "Minimum block size requirement");

     FreeChunk* fc = (FreeChunk*)(blk->_ptr);

     fc->set_size(blk->_word_size);

     fc->link_prev(NULL);   // mark as free

     fc->dontCoalesce();

     assert(fc->is_free(), "just marked it free");

     assert(fc->cantCoalesce(), "just marked it uncoalescable");

   }

 }

 void CompactibleFreeListSpace::refillLinearAllocBlocksIfNeeded() {

   assert_locked();

   if (_smallLinearAllocBlock._ptr == NULL) {

     assert(_smallLinearAllocBlock._word_size == 0,

       "Size of linAB should be zero if the ptr is NULL");

     // Reset the linAB refill and allocation size limit.

     _smallLinearAllocBlock.set(0, 0, 1024*SmallForLinearAlloc, SmallForLinearAlloc);

   }

   refillLinearAllocBlockIfNeeded(&_smallLinearAllocBlock);

 }

 void

 CompactibleFreeListSpace::refillLinearAllocBlockIfNeeded(LinearAllocBlock* blk) {

   assert_locked();

   assert((blk->_ptr == NULL && blk->_word_size == 0) ||

          (blk->_ptr != NULL && blk->_word_size >= MinChunkSize),

          "blk invariant");

   if (blk->_ptr == NULL) {

     refillLinearAllocBlock(blk);

   }

   if (PrintMiscellaneous && Verbose) {

     if (blk->_word_size == 0) {

       warning("CompactibleFreeListSpace(prologue):: Linear allocation failure");

     }

   }

 }

 void

 CompactibleFreeListSpace::refillLinearAllocBlock(LinearAllocBlock* blk) {

   assert_locked();

   assert(blk->_word_size == 0 && blk->_ptr == NULL,

          "linear allocation block should be empty");

   FreeChunk* fc;

   if (blk->_refillSize < SmallForDictionary &&

       (fc = getChunkFromIndexedFreeList(blk->_refillSize)) != NULL) {

     // A linAB's strategy might be to use small sizes to reduce

     // fragmentation but still get the benefits of allocation from a

     // linAB.

   } else {

     fc = getChunkFromDictionary(blk->_refillSize);

   }

   if (fc != NULL) {

     blk->_ptr  = (HeapWord*)fc;

     blk->_word_size = fc->size();

     fc->dontCoalesce();   // to prevent sweeper from sweeping us up

   }

 }

 // Support for concurrent collection policy decisions.

 bool CompactibleFreeListSpace::should_concurrent_collect() const {

   // In the future we might want to add in frgamentation stats --

   // including erosion of the "mountain" into this decision as well.

   return !adaptive_freelists() && linearAllocationWouldFail();

 }

 // Support for compaction

 void CompactibleFreeListSpace::prepare_for_compaction(CompactPoint* cp) {

   SCAN_AND_FORWARD(cp,end,block_is_obj,block_size);

   // prepare_for_compaction() uses the space between live objects

   // so that later phase can skip dead space quickly.  So verification

   // of the free lists doesn't work after.

 }

 #define obj_size(q) adjustObjectSize(oop(q)->size())

 #define adjust_obj_size(s) adjustObjectSize(s)

 void CompactibleFreeListSpace::adjust_pointers() {

   // In other versions of adjust_pointers(), a bail out

   // based on the amount of live data in the generation

   // (i.e., if 0, bail out) may be used.

   // Cannot test used() == 0 here because the free lists have already

   // been mangled by the compaction.

   SCAN_AND_ADJUST_POINTERS(adjust_obj_size);

   // See note about verification in prepare_for_compaction().

 }

 void CompactibleFreeListSpace::compact() {

   SCAN_AND_COMPACT(obj_size);

 }

 // fragmentation_metric = 1 - [sum of (fbs**2) / (sum of fbs)**2]

 // where fbs is free block sizes

 double CompactibleFreeListSpace::flsFrag() const {

   size_t itabFree = totalSizeInIndexedFreeLists();

   double frag = 0.0;

   size_t i;

   for (i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) {

     double sz  = i;

     frag      += _indexedFreeList[i].count() * (sz * sz);

   }

   double totFree = itabFree +

                    _dictionary->total_chunk_size(DEBUG_ONLY(freelistLock()));

   if (totFree > 0) {

     frag = ((frag + _dictionary->sum_of_squared_block_sizes()) /

             (totFree * totFree));

     frag = (double)1.0  - frag;

   } else {

     assert(frag == 0.0, "Follows from totFree == 0");

   }

   return frag;

 }

 void CompactibleFreeListSpace::beginSweepFLCensus(

   float inter_sweep_current,

   float inter_sweep_estimate,

   float intra_sweep_estimate) {

   assert_locked();

   size_t i;

   for (i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) {

     AdaptiveFreeList<FreeChunk>* fl    = &_indexedFreeList[i];

     if (PrintFLSStatistics > 1) {

       gclog_or_tty->print("size[%d] : ", i);

     }

     fl->compute_desired(inter_sweep_current, inter_sweep_estimate, intra_sweep_estimate);

     fl->set_coal_desired((ssize_t)((double)fl->desired() * CMSSmallCoalSurplusPercent));

     fl->set_before_sweep(fl->count());

     fl->set_bfr_surp(fl->surplus());

   }

   _dictionary->begin_sweep_dict_census(CMSLargeCoalSurplusPercent,

                                     inter_sweep_current,

                                     inter_sweep_estimate,

                                     intra_sweep_estimate);

 }

 void CompactibleFreeListSpace::setFLSurplus() {

   assert_locked();

   size_t i;

   for (i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) {

     AdaptiveFreeList<FreeChunk> *fl = &_indexedFreeList[i];

     fl->set_surplus(fl->count() -

                     (ssize_t)((double)fl->desired() * CMSSmallSplitSurplusPercent));

   }

 }

 void CompactibleFreeListSpace::setFLHints() {

   assert_locked();

   size_t i;

   size_t h = IndexSetSize;

   for (i = IndexSetSize - 1; i != 0; i -= IndexSetStride) {

     AdaptiveFreeList<FreeChunk> *fl = &_indexedFreeList[i];

     fl->set_hint(h);

     if (fl->surplus() > 0) {

       h = i;

     }

   }

 }

 void CompactibleFreeListSpace::clearFLCensus() {

   assert_locked();

   size_t i;

   for (i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) {

     AdaptiveFreeList<FreeChunk> *fl = &_indexedFreeList[i];

     fl->set_prev_sweep(fl->count());

     fl->set_coal_births(0);

     fl->set_coal_deaths(0);

     fl->set_split_births(0);

     fl->set_split_deaths(0);

   }

 }

 void CompactibleFreeListSpace::endSweepFLCensus(size_t sweep_count) {

   if (PrintFLSStatistics > 0) {

     HeapWord* largestAddr = (HeapWord*) dictionary()->find_largest_dict();

     gclog_or_tty->print_cr("CMS: Large block " PTR_FORMAT,

                            largestAddr);

   }

   setFLSurplus();

   setFLHints();

   if (PrintGC && PrintFLSCensus > 0) {

     printFLCensus(sweep_count);

   }

   clearFLCensus();

   assert_locked();

   _dictionary->end_sweep_dict_census(CMSLargeSplitSurplusPercent);

 }

 bool CompactibleFreeListSpace::coalOverPopulated(size_t size) {

   if (size < SmallForDictionary) {

     AdaptiveFreeList<FreeChunk> *fl = &_indexedFreeList[size];

     return (fl->coal_desired() < 0) ||

            ((int)fl->count() > fl->coal_desired());

   } else {

     return dictionary()->coal_dict_over_populated(size);

   }

 }

 void CompactibleFreeListSpace::smallCoalBirth(size_t size) {

   assert(size < SmallForDictionary, "Size too large for indexed list");

   AdaptiveFreeList<FreeChunk> *fl = &_indexedFreeList[size];

   fl->increment_coal_births();

   fl->increment_surplus();

 }

 void CompactibleFreeListSpace::smallCoalDeath(size_t size) {

   assert(size < SmallForDictionary, "Size too large for indexed list");

   AdaptiveFreeList<FreeChunk> *fl = &_indexedFreeList[size];

   fl->increment_coal_deaths();

   fl->decrement_surplus();

 }

 void CompactibleFreeListSpace::coalBirth(size_t size) {

   if (size  < SmallForDictionary) {

     smallCoalBirth(size);

   } else {

     dictionary()->dict_census_update(size,

                                    false /* split */,

                                    true /* birth */);

   }

 }

 void CompactibleFreeListSpace::coalDeath(size_t size) {

   if(size  < SmallForDictionary) {

     smallCoalDeath(size);

   } else {

     dictionary()->dict_census_update(size,

                                    false /* split */,

                                    false /* birth */);

   }

 }

 void CompactibleFreeListSpace::smallSplitBirth(size_t size) {

   assert(size < SmallForDictionary, "Size too large for indexed list");

   AdaptiveFreeList<FreeChunk> *fl = &_indexedFreeList[size];

   fl->increment_split_births();

   fl->increment_surplus();

 }

 void CompactibleFreeListSpace::smallSplitDeath(size_t size) {

   assert(size < SmallForDictionary, "Size too large for indexed list");

   AdaptiveFreeList<FreeChunk> *fl = &_indexedFreeList[size];

   fl->increment_split_deaths();

   fl->decrement_surplus();

 }

 void CompactibleFreeListSpace::split_birth(size_t size) {

   if (size  < SmallForDictionary) {

     smallSplitBirth(size);

   } else {

     dictionary()->dict_census_update(size,

                                    true /* split */,

                                    true /* birth */);

   }

 }

 void CompactibleFreeListSpace::splitDeath(size_t size) {

   if (size  < SmallForDictionary) {

     smallSplitDeath(size);

   } else {

     dictionary()->dict_census_update(size,

                                    true /* split */,

                                    false /* birth */);

   }

 }

 void CompactibleFreeListSpace::split(size_t from, size_t to1) {

   size_t to2 = from - to1;

   splitDeath(from);

   split_birth(to1);

   split_birth(to2);

 }

 void CompactibleFreeListSpace::print() const {

   print_on(tty);

 }

 void CompactibleFreeListSpace::prepare_for_verify() {

   assert_locked();

   repairLinearAllocationBlocks();

   // Verify that the SpoolBlocks look like free blocks of

   // appropriate sizes... To be done ...

 }

 class VerifyAllBlksClosure: public BlkClosure {

  private:

   const CompactibleFreeListSpace* _sp;

   const MemRegion                 _span;

   HeapWord*                       _last_addr;

   size_t                          _last_size;

   bool                            _last_was_obj;

   bool                            _last_was_live;

  public:

   VerifyAllBlksClosure(const CompactibleFreeListSpace* sp,

     MemRegion span) :  _sp(sp), _span(span),

                        _last_addr(NULL), _last_size(0),

                        _last_was_obj(false), _last_was_live(false) { }

   virtual size_t do_blk(HeapWord* addr) {

     size_t res;

     bool   was_obj  = false;

     bool   was_live = false;

     if (_sp->block_is_obj(addr)) {

       was_obj = true;

       oop p = oop(addr);

       guarantee(p->is_oop(), "Should be an oop");

       res = _sp->adjustObjectSize(p->size());

       if (_sp->obj_is_alive(addr)) {

         was_live = true;

         p->verify();

       }

     } else {

       FreeChunk* fc = (FreeChunk*)addr;

       res = fc->size();

       if (FLSVerifyLists && !fc->cantCoalesce()) {

         guarantee(_sp->verify_chunk_in_free_list(fc),

                   "Chunk should be on a free list");

       }

     }

     if (res == 0) {

       gclog_or_tty->print_cr("Livelock: no rank reduction!");

       gclog_or_tty->print_cr(

         " Current:  addr = " PTR_FORMAT ", size = " SIZE_FORMAT ", obj = %s, live = %s \n"

         " Previous: addr = " PTR_FORMAT ", size = " SIZE_FORMAT ", obj = %s, live = %s \n",

         addr,       res,        was_obj      ?"true":"false", was_live      ?"true":"false",

         _last_addr, _last_size, _last_was_obj?"true":"false", _last_was_live?"true":"false");

       _sp->print_on(gclog_or_tty);

       guarantee(false, "Seppuku!");

     }

     _last_addr = addr;

     _last_size = res;

     _last_was_obj  = was_obj;

     _last_was_live = was_live;

     return res;

   }

 };

 class VerifyAllOopsClosure: public OopClosure {

  private:

   const CMSCollector*             _collector;

   const CompactibleFreeListSpace* _sp;

   const MemRegion                 _span;

   const bool                      _past_remark;

   const CMSBitMap*                _bit_map;

  protected:

   void do_oop(void* p, oop obj) {

     if (_span.contains(obj)) { // the interior oop points into CMS heap

       if (!_span.contains(p)) { // reference from outside CMS heap

         // Should be a valid object; the first disjunct below allows

         // us to sidestep an assertion in block_is_obj() that insists

         // that p be in _sp. Note that several generations (and spaces)

         // are spanned by _span (CMS heap) above.

         guarantee(!_sp->is_in_reserved(obj) ||

                   _sp->block_is_obj((HeapWord*)obj),

                   "Should be an object");

         guarantee(obj->is_oop(), "Should be an oop");

         obj->verify();

         if (_past_remark) {

           // Remark has been completed, the object should be marked

           _bit_map->isMarked((HeapWord*)obj);

         }

       } else { // reference within CMS heap

         if (_past_remark) {

           // Remark has been completed -- so the referent should have

           // been marked, if referring object is.

           if (_bit_map->isMarked(_collector->block_start(p))) {

             guarantee(_bit_map->isMarked((HeapWord*)obj), "Marking error?");

           }

         }

       }

     } else if (_sp->is_in_reserved(p)) {

       // the reference is from FLS, and points out of FLS

       guarantee(obj->is_oop(), "Should be an oop");

       obj->verify();

     }

   }

   template <class T> void do_oop_work(T* p) {

     T heap_oop = oopDesc::load_heap_oop(p);

     if (!oopDesc::is_null(heap_oop)) {

       oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);

       do_oop(p, obj);

     }

   }

  public:

   VerifyAllOopsClosure(const CMSCollector* collector,

     const CompactibleFreeListSpace* sp, MemRegion span,

     bool past_remark, CMSBitMap* bit_map) :

     _collector(collector), _sp(sp), _span(span),

     _past_remark(past_remark), _bit_map(bit_map) { }

   virtual void do_oop(oop* p)       { VerifyAllOopsClosure::do_oop_work(p); }

   virtual void do_oop(narrowOop* p) { VerifyAllOopsClosure::do_oop_work(p); }

 };

 void CompactibleFreeListSpace::verify() const {

   assert_lock_strong(&_freelistLock);

   verify_objects_initialized();

   MemRegion span = _collector->_span;

   bool past_remark = (_collector->abstract_state() ==

                       CMSCollector::Sweeping);

   ResourceMark rm;

   HandleMark  hm;

   // Check integrity of CFL data structures

   _promoInfo.verify();

   _dictionary->verify();

   if (FLSVerifyIndexTable) {

     verifyIndexedFreeLists();

   }

   // Check integrity of all objects and free blocks in space

   {

     VerifyAllBlksClosure cl(this, span);

     ((CompactibleFreeListSpace*)this)->blk_iterate(&cl);  // cast off const

   }

   // Check that all references in the heap to FLS

   // are to valid objects in FLS or that references in

   // FLS are to valid objects elsewhere in the heap

   if (FLSVerifyAllHeapReferences)

   {

     VerifyAllOopsClosure cl(_collector, this, span, past_remark,

       _collector->markBitMap());

     CollectedHeap* ch = Universe::heap();

     // Iterate over all oops in the heap. Uses the _no_header version

     // since we are not interested in following the klass pointers.

     ch->oop_iterate_no_header(&cl);

   }

   if (VerifyObjectStartArray) {

     // Verify the block offset table

     _bt.verify();

   }

 }

 #ifndef PRODUCT

 void CompactibleFreeListSpace::verifyFreeLists() const {

   if (FLSVerifyLists) {

     _dictionary->verify();

     verifyIndexedFreeLists();

   } else {

     if (FLSVerifyDictionary) {

       _dictionary->verify();

     }

     if (FLSVerifyIndexTable) {

       verifyIndexedFreeLists();

     }

   }

 }

 #endif

 void CompactibleFreeListSpace::verifyIndexedFreeLists() const {

   size_t i = 0;

   for (; i < IndexSetStart; i++) {

     guarantee(_indexedFreeList[i].head() == NULL, "should be NULL");

   }

   for (; i < IndexSetSize; i++) {

     verifyIndexedFreeList(i);

   }

 }

 void CompactibleFreeListSpace::verifyIndexedFreeList(size_t size) const {

   FreeChunk* fc   =  _indexedFreeList[size].head();

   FreeChunk* tail =  _indexedFreeList[size].tail();

   size_t    num = _indexedFreeList[size].count();

   size_t      n = 0;

   guarantee(((size >= IndexSetStart) && (size % IndexSetStride == 0)) || fc == NULL,

             "Slot should have been empty");

   for (; fc != NULL; fc = fc->next(), n++) {

     guarantee(fc->size() == size, "Size inconsistency");

     guarantee(fc->is_free(), "!free?");

     guarantee(fc->next() == NULL || fc->next()->prev() == fc, "Broken list");

     guarantee((fc->next() == NULL) == (fc == tail), "Incorrect tail");

   }

   guarantee(n == num, "Incorrect count");

 }

 #ifndef PRODUCT

 void CompactibleFreeListSpace::check_free_list_consistency() const {

   assert((TreeChunk<FreeChunk, AdaptiveFreeList>::min_size() <= IndexSetSize),

     "Some sizes can't be allocated without recourse to"

     " linear allocation buffers");

   assert((TreeChunk<FreeChunk, AdaptiveFreeList>::min_size()*HeapWordSize == sizeof(TreeChunk<FreeChunk, AdaptiveFreeList>)),

     "else MIN_TREE_CHUNK_SIZE is wrong");

   assert(IndexSetStart != 0, "IndexSetStart not initialized");

   assert(IndexSetStride != 0, "IndexSetStride not initialized");

 }

 #endif

 void CompactibleFreeListSpace::printFLCensus(size_t sweep_count) const {

   assert_lock_strong(&_freelistLock);

   AdaptiveFreeList<FreeChunk> total;

   gclog_or_tty->print("end sweep# " SIZE_FORMAT "\n", sweep_count);

   AdaptiveFreeList<FreeChunk>::print_labels_on(gclog_or_tty, "size");

   size_t total_free = 0;

   for (size_t i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) {

     const AdaptiveFreeList<FreeChunk> *fl = &_indexedFreeList[i];

     total_free += fl->count() * fl->size();

     if (i % (40*IndexSetStride) == 0) {

       AdaptiveFreeList<FreeChunk>::print_labels_on(gclog_or_tty, "size");

     }

     fl->print_on(gclog_or_tty);

     total.set_bfr_surp(    total.bfr_surp()     + fl->bfr_surp()    );

     total.set_surplus(    total.surplus()     + fl->surplus()    );

     total.set_desired(    total.desired()     + fl->desired()    );

     total.set_prev_sweep(  total.prev_sweep()   + fl->prev_sweep()  );

     total.set_before_sweep(total.before_sweep() + fl->before_sweep());

     total.set_count(      total.count()       + fl->count()      );

     total.set_coal_births( total.coal_births()  + fl->coal_births() );

     total.set_coal_deaths( total.coal_deaths()  + fl->coal_deaths() );

     total.set_split_births(total.split_births() + fl->split_births());

     total.set_split_deaths(total.split_deaths() + fl->split_deaths());

   }

   total.print_on(gclog_or_tty, "TOTAL");

   gclog_or_tty->print_cr("Total free in indexed lists "

                          SIZE_FORMAT " words", total_free);

   gclog_or_tty->print("growth: %8.5f  deficit: %8.5f\n",

     (double)(total.split_births()+total.coal_births()-total.split_deaths()-total.coal_deaths())/

             (total.prev_sweep() != 0 ? (double)total.prev_sweep() : 1.0),

     (double)(total.desired() - total.count())/(total.desired() != 0 ? (double)total.desired() : 1.0));

   _dictionary->print_dict_census();

 }

 ///////////////////////////////////////////////////////////////////////////

 // CFLS_LAB

 ///////////////////////////////////////////////////////////////////////////

 #define VECTOR_257(x)                                                                                  \

   /* 1  2  3  4  5  6  7  8  9 1x 11 12 13 14 15 16 17 18 19 2x 21 22 23 24 25 26 27 28 29 3x 31 32 */ \

   {  x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x,   \

      x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x,   \

      x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x,   \

      x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x,   \

      x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x,   \

      x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x,   \

      x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x,   \

      x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x,   \

      x }

 // Initialize with default setting of CMSParPromoteBlocksToClaim, _not_

 // OldPLABSize, whose static default is different; if overridden at the

 // command-line, this will get reinitialized via a call to

 // modify_initialization() below.

 AdaptiveWeightedAverage CFLS_LAB::_blocks_to_claim[]    =

   VECTOR_257(AdaptiveWeightedAverage(OldPLABWeight, (float)CMSParPromoteBlocksToClaim));

 size_t CFLS_LAB::_global_num_blocks[]  = VECTOR_257(0);

 uint   CFLS_LAB::_global_num_workers[] = VECTOR_257(0);

 CFLS_LAB::CFLS_LAB(CompactibleFreeListSpace* cfls) :

   _cfls(cfls)

 {

   assert(CompactibleFreeListSpace::IndexSetSize == 257, "Modify VECTOR_257() macro above");

   for (size_t i = CompactibleFreeListSpace::IndexSetStart;

        i < CompactibleFreeListSpace::IndexSetSize;

        i += CompactibleFreeListSpace::IndexSetStride) {

     _indexedFreeList[i].set_size(i);

     _num_blocks[i] = 0;

   }

 }

 static bool _CFLS_LAB_modified = false;

 void CFLS_LAB::modify_initialization(size_t n, unsigned wt) {

   assert(!_CFLS_LAB_modified, "Call only once");

   _CFLS_LAB_modified = true;

   for (size_t i = CompactibleFreeListSpace::IndexSetStart;

        i < CompactibleFreeListSpace::IndexSetSize;

        i += CompactibleFreeListSpace::IndexSetStride) {

     _blocks_to_claim[i].modify(n, wt, true /* force */);

   }

 }

 HeapWord* CFLS_LAB::alloc(size_t word_sz) {

   FreeChunk* res;

   assert(word_sz == _cfls->adjustObjectSize(word_sz), "Error");

   if (word_sz >=  CompactibleFreeListSpace::IndexSetSize) {

     // This locking manages sync with other large object allocations.

     MutexLockerEx x(_cfls->parDictionaryAllocLock(),

                     Mutex::_no_safepoint_check_flag);

     res = _cfls->getChunkFromDictionaryExact(word_sz);

     if (res == NULL) return NULL;

   } else {

     AdaptiveFreeList<FreeChunk>* fl = &_indexedFreeList[word_sz];

     if (fl->count() == 0) {

       // Attempt to refill this local free list.

       get_from_global_pool(word_sz, fl);

       // If it didn't work, give up.

       if (fl->count() == 0) return NULL;

     }

     res = fl->get_chunk_at_head();

     assert(res != NULL, "Why was count non-zero?");

   }

   res->markNotFree();

   assert(!res->is_free(), "shouldn't be marked free");

   assert(oop(res)->klass_or_null() == NULL, "should look uninitialized");

   // mangle a just allocated object with a distinct pattern.

   debug_only(res->mangleAllocated(word_sz));

   return (HeapWord*)res;

 }

 // Get a chunk of blocks of the right size and update related