jdk8-mips64-public/hotspot: src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.cpp@e9ff18c4ace7 (annotated)

src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.cpp@e9ff18c4ace7 (annotated)

src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.cpp

Wed, 02 Jun 2010 22:45:42 -0700

author: jrose
date: Wed, 02 Jun 2010 22:45:42 -0700
changeset 1934: e9ff18c4ace7
parent 1907: c18cbe5936b8
parent 1926: 2d127394260e
child 2071: be3f9c242c9d
permissions: -rw-r--r--

Merge

 /*
  * Copyright (c) 2001, 2009, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  *
  */
 # include "incls/_precompiled.incl"
 # include "incls/_compactibleFreeListSpace.cpp.incl"
 /////////////////////////////////////////////////////////////////////////
 //// CompactibleFreeListSpace
 /////////////////////////////////////////////////////////////////////////
 // highest ranked  free list lock rank
 int CompactibleFreeListSpace::_lockRank = Mutex::leaf + 3;
 // Defaults are 0 so things will break badly if incorrectly initialized.
 int CompactibleFreeListSpace::IndexSetStart  = 0;
 int CompactibleFreeListSpace::IndexSetStride = 0;
 size_t MinChunkSize = 0;
 void CompactibleFreeListSpace::set_cms_values() {
   // Set CMS global values
   assert(MinChunkSize == 0, "already set");
   #define numQuanta(x,y) ((x+y-1)/y)
   MinChunkSize = numQuanta(sizeof(FreeChunk), MinObjAlignmentInBytes) * MinObjAlignment;
   assert(IndexSetStart == 0 && IndexSetStride == 0, "already set");
   IndexSetStart  = MinObjAlignment;
   IndexSetStride = MinObjAlignment;
 }
 // Constructor
 CompactibleFreeListSpace::CompactibleFreeListSpace(BlockOffsetSharedArray* bs,
   MemRegion mr, bool use_adaptive_freelists,
   FreeBlockDictionary::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)
 {
   _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::dictionarySplayTree:
     case FreeBlockDictionary::dictionarySkipList:
     default:
       warning("dictionaryChoice: selected option not understood; using"
               " default BinaryTreeDictionary implementation instead.");
     case FreeBlockDictionary::dictionaryBinaryTree:
       _dictionary = new BinaryTreeDictionary(mr);
       break;
   }
   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->getChunk(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() ,
 *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;
   }
   checkFreeListConsistency();
   // Initialize locks for parallel case.
   if (ParallelGCThreads > 0) {
     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 (int 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->setSize(mr.word_size());
     if (mr.word_size() >= IndexSetSize ) {
       returnChunkToDictionary(fc);
     } else {
       _bt.verify_not_unallocated((HeapWord*)fc, fc->size());
       _indexedFreeList[mr.word_size()].returnChunkAtHead(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()->findLargestDict();
     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() ,
 *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_returnedBytes(0);
   }
 }
 size_t CompactibleFreeListSpace::sumIndexedFreeListArrayReturnedBytes() {
   size_t sum = 0;
   for (size_t i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) {
     sum += _indexedFreeList[i].allocation_stats()->returnedBytes();
   }
   return sum;
 }
 size_t CompactibleFreeListSpace::totalCountInIndexedFreeLists() const {
   size_t count = 0;
   for (int i = (int)MinChunkSize; 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()->totalCount();
   if (_smallLinearAllocBlock._word_size != 0) {
     num++;
   }
   return num;
 }
 #endif
 bool CompactibleFreeListSpace::is_free_block(const HeapWord* p) const {
   FreeChunk* fc = (FreeChunk*) p;
   return fc->isFree();
 }
 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->totalChunkSize(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->maxChunkSize();
   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 CompactibleFreeListSpace::print_indexed_free_lists(outputStream* st)
 const {
   reportIndexedFreeListStatistics();
   gclog_or_tty->print_cr("Layout of Indexed Freelists");
   gclog_or_tty->print_cr("---------------------------");
   FreeList::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->reportStatistics();
   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->reportStatistics();
   if (PrintFLSStatistics > 1) {
     reportIndexedFreeListStatistics();
     size_t totalSize = totalSizeInIndexedFreeLists() +
                        _dictionary->totalChunkSize(DEBUG_ONLY(freelistLock()));
     gclog_or_tty->print(" free=%ld frag=%1.4f\n", totalSize, flsFrag());
   }
 }
 void CompactibleFreeListSpace::reportIndexedFreeListStatistics() const {
   assert_lock_strong(&_freelistLock);
   gclog_or_tty->print("Statistics for IndexedFreeLists:\n"
                       "--------------------------------\n");
   size_t totalSize = totalSizeInIndexedFreeLists();
   size_t   freeBlocks = numFreeBlocksInIndexedFreeLists();
   gclog_or_tty->print("Total Free Space: %d\n", totalSize);
   gclog_or_tty->print("Max   Chunk Size: %d\n", maxChunkSizeInIndexedFreeLists());
   gclog_or_tty->print("Number of Blocks: %d\n", freeBlocks);
   if (freeBlocks != 0) {
     gclog_or_tty->print("Av.  Block  Size: %d\n", totalSize/freeBlocks);
   }
 }
 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 || 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(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(OopClosure);
   walk_mem_region_with_cl_DECL(FilteringClosure);
 public:
   FreeListSpace_DCTOC(CompactibleFreeListSpace* sp,
                       CMSCollector* collector,
                       OopClosure* 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) {             \
    if (SharedHeap::heap()->n_par_threads() > 0) {                               \
      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(OopClosure)
 FreeListSpace_DCTOC__walk_mem_region_with_cl_DEFN(FilteringClosure)
 DirtyCardToOopClosure*
 CompactibleFreeListSpace::new_dcto_cl(OopClosure* 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(OopClosure* 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, OopClosure* 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->isFree()) {
       // 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->isFree()) {
       // 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());
   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.
   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.
       klassOop k = ((volatile oopDesc*)p)->klass_or_null();
       if (k != NULL) {
         assert(k->is_oop(true /* ignore mark word */), "Should really be klass oop.");
         oop o = (oop)p;
         assert(o->is_parsable(), "Should be parsable");
         assert(o->is_oop(true /* ignore mark word */), "Should be an oop.");
         size_t res = o->size_given_klass(k->klass_part());
         res = adjustObjectSize(res);
         assert(res != 0, "Block size should not be 0");
         return res;
       }
     }
   }
 }
 // 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.
       klassOop k = ((volatile oopDesc*)p)->klass_or_null();
       if (k != NULL &&
           ((oopDesc*)p)->is_parsable() &&
           ((oopDesc*)p)->is_conc_safe()) {
         assert(k->is_oop(), "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->klass_part());
         res = adjustObjectSize(res);
         assert(res != 0, "Block size should not be 0");
         return res;
       } else {
         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->isFree()) {
     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(ParallelGCThreads > 0 || _bt.block_start(p) == p, "Should be a block boundary");
   if (FreeChunk::indicatesFreeChunk(p)) return false;
   klassOop 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 (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.
   if (_collector->abstract_state() == CMSCollector::Sweeping) {
     CMSBitMap* live_map = _collector->markBitMap();
     return live_map->isMarked((HeapWord*) p);
   } else {
     // If we're not currently sweeping and we haven't swept the perm gen in
     // the previous concurrent cycle then we may have dead but unswept objects
     // in the perm gen. In this case, we use the "deadness" information
     // that we had saved in perm_gen_verify_bit_map at the last sweep.
     if (!CMSClassUnloadingEnabled && _collector->_permGen->reserved().contains(p)) {
       if (_collector->verifying()) {
         CMSBitMap* dead_map = _collector->perm_gen_verify_bit_map();
         // Object is marked in the dead_map bitmap at the previous sweep
         // when we know that it's dead; if the bitmap is not allocated then
         // the object is alive.
         return (dead_map->sizeInBits() == 0) // bit_map has been allocated
                || !dead_map->par_isMarked((HeapWord*) p);
       } else {
         return false; // We can't say for sure if it's live, so we say that it's dead.
       }
     }
   }
   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->isFree()) {
     // 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->isFree(), "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) {
     FreeList* fl = &_indexedFreeList[i];
     if (fl->head()) {
       ret = getFromListGreater(fl, numWords);
       assert(ret == NULL || ret->isFree(), "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()->getChunk(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->isFree(), "This chunk should be free");
       ret->linkPrev(NULL);
     }
     assert(ret == NULL || ret->isFree(), "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()].verifyChunkInFreeLists(fc);
 }
 bool CompactibleFreeListSpace::verifyChunkInFreeLists(FreeChunk* fc) const {
   if (fc->size() >= IndexSetSize) {
     return dictionary()->verifyChunkInFreeLists(fc);
   } else {
     return verifyChunkInIndexedFreeLists(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->isFree(), "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);
     splitBirth(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) {
     splitBirth(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;
     splitBirth(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.
     _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;
     splitBirth(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.
     _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].getChunkAtHead();
   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].getChunkAtHead();
         } 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->setSize(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].returnChunkAtTail(curFc, false);
             _bt.mark_block((HeapWord*)curFc, size);
             splitBirth(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->setSize(size);
           _bt.mark_block((HeapWord*)curFc, size);
           splitBirth(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->isFree(), "Should be returning a free chunk");
   return fc;
 }
 FreeChunk*
 CompactibleFreeListSpace::getChunkFromDictionary(size_t size) {
   assert_locked();
   FreeChunk* fc = _dictionary->getChunk(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->getChunk(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, "getChunk() guarantee");
   if (fc->size() < size + MinChunkSize) {
     // Return the chunk to the dictionary and go get a bigger one.
     returnChunkToDictionary(fc);
     fc = _dictionary->getChunk(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->returnChunk(chunk);
 #ifndef PRODUCT
   if (CMSCollector::abstract_state() != CMSCollector::Sweeping) {
     TreeChunk::as_TreeChunk(chunk)->list()->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].returnChunkAtTail(fc);
   } else {
     _indexedFreeList[size].returnChunkAtHead(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()->findLargestDict();  // get largest block
     if (ec != NULL && ec->end() == 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->setSize(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->setSize(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->removeChunk(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].removeChunk(fc);
   debug_only(fc->clearNext());
   debug_only(fc->clearPrev());
   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) {
     FreeList* it   = _indexedFreeList;
     size_t    hint = _indexedFreeList[start].hint();
     while (hint < IndexSetSize) {
       assert(hint % MinObjAlignment == 0, "hint should be aligned");
       FreeList *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->isFree(),
           "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(FreeList* 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->removeChunk(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->isFree(),
     "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->setSize(rem_size);
   ffc->linkNext(NULL);
   ffc->linkPrev(NULL); // Mark as a free block for other (parallel) GC threads.
   // Above must occur before BOT is updated below.
   // adjust block offset table
   _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();
     returnChunkToFreeList(ffc);
     split(size, rem_size);
     if (is_par) _indexedFreeListParLocks[rem_size]->unlock();
   } else {
     returnChunkToDictionary(ffc);
     split(size ,rem_size);
   }
   chunk->setSize(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() {
   // 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(BlockOffsetArrayUseUnallocatedBlock ?
                       unallocated_block() : end());
   // 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?");
   guarantee(SharedHeap::heap()->n_par_threads() == 0,
             "Shouldn't be called (yet) during parallel part of 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->setSize(blk->_word_size);
     fc->linkPrev(NULL);   // mark as free
     fc->dontCoalesce();
     assert(fc->isFree(), "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->totalChunkSize(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) {
     FreeList* 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_coalDesired((ssize_t)((double)fl->desired() * CMSSmallCoalSurplusPercent));
     fl->set_beforeSweep(fl->count());
     fl->set_bfrSurp(fl->surplus());
   }
   _dictionary->beginSweepDictCensus(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) {
     FreeList *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) {
     FreeList *fl = &_indexedFreeList[i];
     fl->set_hint(h);
     if (fl->surplus() > 0) {
       h = i;
     }
   }
 }
 void CompactibleFreeListSpace::clearFLCensus() {
   assert_locked();
   int i;
   for (i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) {
     FreeList *fl = &_indexedFreeList[i];
     fl->set_prevSweep(fl->count());
     fl->set_coalBirths(0);
     fl->set_coalDeaths(0);
     fl->set_splitBirths(0);
     fl->set_splitDeaths(0);
   }
 }
 void CompactibleFreeListSpace::endSweepFLCensus(size_t sweep_count) {
   if (PrintFLSStatistics > 0) {
     HeapWord* largestAddr = (HeapWord*) dictionary()->findLargestDict();
     gclog_or_tty->print_cr("CMS: Large block " PTR_FORMAT,
                            largestAddr);
   }
   setFLSurplus();
   setFLHints();
   if (PrintGC && PrintFLSCensus > 0) {
     printFLCensus(sweep_count);
   }
   clearFLCensus();
   assert_locked();
   _dictionary->endSweepDictCensus(CMSLargeSplitSurplusPercent);
 }
 bool CompactibleFreeListSpace::coalOverPopulated(size_t size) {
   if (size < SmallForDictionary) {
     FreeList *fl = &_indexedFreeList[size];
     return (fl->coalDesired() < 0) ||
            ((int)fl->count() > fl->coalDesired());
   } else {
     return dictionary()->coalDictOverPopulated(size);
   }
 }
 void CompactibleFreeListSpace::smallCoalBirth(size_t size) {
   assert(size < SmallForDictionary, "Size too large for indexed list");
   FreeList *fl = &_indexedFreeList[size];
   fl->increment_coalBirths();
   fl->increment_surplus();
 }
 void CompactibleFreeListSpace::smallCoalDeath(size_t size) {
   assert(size < SmallForDictionary, "Size too large for indexed list");
   FreeList *fl = &_indexedFreeList[size];
   fl->increment_coalDeaths();
   fl->decrement_surplus();
 }
 void CompactibleFreeListSpace::coalBirth(size_t size) {
   if (size  < SmallForDictionary) {
     smallCoalBirth(size);
   } else {
     dictionary()->dictCensusUpdate(size,
                                    false /* split */,
                                    true /* birth */);
   }
 }
 void CompactibleFreeListSpace::coalDeath(size_t size) {
   if(size  < SmallForDictionary) {
     smallCoalDeath(size);
   } else {
     dictionary()->dictCensusUpdate(size,
                                    false /* split */,
                                    false /* birth */);
   }
 }
 void CompactibleFreeListSpace::smallSplitBirth(size_t size) {
   assert(size < SmallForDictionary, "Size too large for indexed list");
   FreeList *fl = &_indexedFreeList[size];
   fl->increment_splitBirths();
   fl->increment_surplus();
 }
 void CompactibleFreeListSpace::smallSplitDeath(size_t size) {
   assert(size < SmallForDictionary, "Size too large for indexed list");
   FreeList *fl = &_indexedFreeList[size];
   fl->increment_splitDeaths();
   fl->decrement_surplus();
 }
 void CompactibleFreeListSpace::splitBirth(size_t size) {
   if (size  < SmallForDictionary) {
     smallSplitBirth(size);
   } else {
     dictionary()->dictCensusUpdate(size,
                                    true /* split */,
                                    true /* birth */);
   }
 }
 void CompactibleFreeListSpace::splitDeath(size_t size) {
   if (size  < SmallForDictionary) {
     smallSplitDeath(size);
   } else {
     dictionary()->dictCensusUpdate(size,
                                    true /* split */,
                                    false /* birth */);
   }
 }
 void CompactibleFreeListSpace::split(size_t from, size_t to1) {
   size_t to2 = from - to1;
   splitDeath(from);
   splitBirth(to1);
   splitBirth(to2);
 }
 void CompactibleFreeListSpace::print() const {
   tty->print(" CompactibleFreeListSpace");
   Space::print();
 }
 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;
  public:
   VerifyAllBlksClosure(const CompactibleFreeListSpace* sp,
     MemRegion span) :  _sp(sp), _span(span) { }
   virtual size_t do_blk(HeapWord* addr) {
     size_t res;
     if (_sp->block_is_obj(addr)) {
       oop p = oop(addr);
       guarantee(p->is_oop(), "Should be an oop");
       res = _sp->adjustObjectSize(p->size());
       if (_sp->obj_is_alive(addr)) {
         p->verify();
       }
     } else {
       FreeChunk* fc = (FreeChunk*)addr;
       res = fc->size();
       if (FLSVerifyLists && !fc->cantCoalesce()) {
         guarantee(_sp->verifyChunkInFreeLists(fc),
                   "Chunk should be on a free list");
       }
     }
     guarantee(res != 0, "Livelock: no rank reduction!");
     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) :
     OopClosure(), _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(bool ignored) 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();
     ch->oop_iterate(&cl);              // all oops in generations
     ch->permanent_oop_iterate(&cl);    // all oops in perm gen
   }
   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 < MinChunkSize; 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 % 2 == 0) || fc == NULL, "Odd slots should be empty");
   for (; fc != NULL; fc = fc->next(), n++) {
     guarantee(fc->size() == size, "Size inconsistency");
     guarantee(fc->isFree(), "!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::checkFreeListConsistency() const {
   assert(_dictionary->minSize() <= IndexSetSize,
     "Some sizes can't be allocated without recourse to"
     " linear allocation buffers");
   assert(MIN_TREE_CHUNK_SIZE*HeapWordSize == sizeof(TreeChunk),
     "else MIN_TREE_CHUNK_SIZE is wrong");
   assert((IndexSetStride == 2 && IndexSetStart == 2) ||
          (IndexSetStride == 1 && IndexSetStart == 1), "just checking");
   assert((IndexSetStride != 2) || (MinChunkSize % 2 == 0),
       "Some for-loops may be incorrectly initialized");
   assert((IndexSetStride != 2) || (IndexSetSize % 2 == 1),
       "For-loops that iterate over IndexSet with stride 2 may be wrong");
 }
 #endif
 void CompactibleFreeListSpace::printFLCensus(size_t sweep_count) const {
   assert_lock_strong(&_freelistLock);
   FreeList total;
   gclog_or_tty->print("end sweep# " SIZE_FORMAT "\n", sweep_count);
   FreeList::print_labels_on(gclog_or_tty, "size");
   size_t totalFree = 0;
   for (size_t i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) {
     const FreeList *fl = &_indexedFreeList[i];
     totalFree += fl->count() * fl->size();
     if (i % (40*IndexSetStride) == 0) {
       FreeList::print_labels_on(gclog_or_tty, "size");
     }
     fl->print_on(gclog_or_tty);
     total.set_bfrSurp(    total.bfrSurp()     + fl->bfrSurp()    );
     total.set_surplus(    total.surplus()     + fl->surplus()    );
     total.set_desired(    total.desired()     + fl->desired()    );
     total.set_prevSweep(  total.prevSweep()   + fl->prevSweep()  );
     total.set_beforeSweep(total.beforeSweep() + fl->beforeSweep());
     total.set_count(      total.count()       + fl->count()      );
     total.set_coalBirths( total.coalBirths()  + fl->coalBirths() );
     total.set_coalDeaths( total.coalDeaths()  + fl->coalDeaths() );
     total.set_splitBirths(total.splitBirths() + fl->splitBirths());
     total.set_splitDeaths(total.splitDeaths() + fl->splitDeaths());
   }
   total.print_on(gclog_or_tty, "TOTAL");
   gclog_or_tty->print_cr("Total free in indexed lists "
                          SIZE_FORMAT " words", totalFree);
   gclog_or_tty->print("growth: %8.5f  deficit: %8.5f\n",
     (double)(total.splitBirths()+total.coalBirths()-total.splitDeaths()-total.coalDeaths())/
             (total.prevSweep() != 0 ? (double)total.prevSweep() : 1.0),
     (double)(total.desired() - total.count())/(total.desired() != 0 ? (double)total.desired() : 1.0));
   _dictionary->printDictCensus();
 }
 ///////////////////////////////////////////////////////////////////////////
 // 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);
 int    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;
   word_sz = _cfls->adjustObjectSize(word_sz);
   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 {
     FreeList* 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->getChunkAtHead();
     assert(res != NULL, "Why was count non-zero?");
   }
   res->markNotFree();
   assert(!res->isFree(), "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
 // book-keeping stats
 void CFLS_LAB::get_from_global_pool(size_t word_sz, FreeList* fl) {
   // Get the #blocks we want to claim
   size_t n_blks = (size_t)_blocks_to_claim[word_sz].average();
   assert(n_blks > 0, "Error");
   assert(ResizePLAB || n_blks == OldPLABSize, "Error");
   // In some cases, when the application has a phase change,
   // there may be a sudden and sharp shift in the object survival
   // profile, and updating the counts at the end of a scavenge
   // may not be quick enough, giving rise to large scavenge pauses
   // during these phase changes. It is beneficial to detect such
   // changes on-the-fly during a scavenge and avoid such a phase-change
   // pothole. The following code is a heuristic attempt to do that.
   // It is protected by a product flag until we have gained
   // enough experience with this heuristic and fine-tuned its behaviour.
   // WARNING: This might increase fragmentation if we overreact to
   // small spikes, so some kind of historical smoothing based on
   // previous experience with the greater reactivity might be useful.
   // Lacking sufficient experience, CMSOldPLABResizeQuicker is disabled by
   // default.
   if (ResizeOldPLAB && CMSOldPLABResizeQuicker) {
     size_t multiple = _num_blocks[word_sz]/(CMSOldPLABToleranceFactor*CMSOldPLABNumRefills*n_blks);
     n_blks +=  CMSOldPLABReactivityFactor*multiple*n_blks;
     n_blks = MIN2(n_blks, CMSOldPLABMax);
   }
   assert(n_blks > 0, "Error");
   _cfls->par_get_chunk_of_blocks(word_sz, n_blks, fl);
   // Update stats table entry for this block size
   _num_blocks[word_sz] += fl->count();
 }
 void CFLS_LAB::compute_desired_plab_size() {
   for (size_t i =  CompactibleFreeListSpace::IndexSetStart;
        i < CompactibleFreeListSpace::IndexSetSize;
        i += CompactibleFreeListSpace::IndexSetStride) {
     assert((_global_num_workers[i] == 0) == (_global_num_blocks[i] == 0),
            "Counter inconsistency");
     if (_global_num_workers[i] > 0) {
       // Need to smooth wrt historical average
       if (ResizeOldPLAB) {
         _blocks_to_claim[i].sample(
           MAX2((size_t)CMSOldPLABMin,
           MIN2((size_t)CMSOldPLABMax,
                _global_num_blocks[i]/(_global_num_workers[i]*CMSOldPLABNumRefills))));
       }
       // Reset counters for next round
       _global_num_workers[i] = 0;
       _global_num_blocks[i] = 0;
       if (PrintOldPLAB) {
         gclog_or_tty->print_cr("[%d]: %d", i, (size_t)_blocks_to_claim[i].average());
       }
     }
   }
 }
 void CFLS_LAB::retire(int tid) {
   // We run this single threaded with the world stopped;
   // so no need for locks and such.
 #define CFLS_LAB_PARALLEL_ACCESS 0
   NOT_PRODUCT(Thread* t = Thread::current();)
   assert(Thread::current()->is_VM_thread(), "Error");
   assert(CompactibleFreeListSpace::IndexSetStart == CompactibleFreeListSpace::IndexSetStride,
          "Will access to uninitialized slot below");
 #if CFLS_LAB_PARALLEL_ACCESS
   for (size_t i = CompactibleFreeListSpace::IndexSetSize - 1;
        i > 0;
        i -= CompactibleFreeListSpace::IndexSetStride) {
 #else // CFLS_LAB_PARALLEL_ACCESS
   for (size_t i =  CompactibleFreeListSpace::IndexSetStart;
        i < CompactibleFreeListSpace::IndexSetSize;
        i += CompactibleFreeListSpace::IndexSetStride) {
 #endif // !CFLS_LAB_PARALLEL_ACCESS
     assert(_num_blocks[i] >= (size_t)_indexedFreeList[i].count(),
            "Can't retire more than what we obtained");
     if (_num_blocks[i] > 0) {
       size_t num_retire =  _indexedFreeList[i].count();
       assert(_num_blocks[i] > num_retire, "Should have used at least one");
       {
 #if CFLS_LAB_PARALLEL_ACCESS
         MutexLockerEx x(_cfls->_indexedFreeListParLocks[i],
                         Mutex::_no_safepoint_check_flag);
 #endif // CFLS_LAB_PARALLEL_ACCESS
         // Update globals stats for num_blocks used
         _global_num_blocks[i] += (_num_blocks[i] - num_retire);
         _global_num_workers[i]++;
         assert(_global_num_workers[i] <= (ssize_t)ParallelGCThreads, "Too big");
         if (num_retire > 0) {
           _cfls->_indexedFreeList[i].prepend(&_indexedFreeList[i]);
           // Reset this list.
           _indexedFreeList[i] = FreeList();
           _indexedFreeList[i].set_size(i);
         }
       }
       if (PrintOldPLAB) {
         gclog_or_tty->print_cr("%d[%d]: %d/%d/%d",
                                tid, i, num_retire, _num_blocks[i], (size_t)_blocks_to_claim[i].average());
       }
       // Reset stats for next round
       _num_blocks[i]         = 0;
     }
   }
 }
 void CompactibleFreeListSpace:: par_get_chunk_of_blocks(size_t word_sz, size_t n, FreeList* fl) {
   assert(fl->count() == 0, "Precondition.");
   assert(word_sz < CompactibleFreeListSpace::IndexSetSize,
          "Precondition");
   // We'll try all multiples of word_sz in the indexed set, starting with
   // word_sz itself and, if CMSSplitIndexedFreeListBlocks, try larger multiples,
   // then try getting a big chunk and splitting it.
   {
     bool found;
     int  k;
     size_t cur_sz;
     for (k = 1, cur_sz = k * word_sz, found = false;
          (cur_sz < CompactibleFreeListSpace::IndexSetSize) &&
          (CMSSplitIndexedFreeListBlocks || k <= 1);
          k++, cur_sz = k * word_sz) {
       FreeList* gfl = &_indexedFreeList[cur_sz];
       FreeList fl_for_cur_sz;  // Empty.
       fl_for_cur_sz.set_size(cur_sz);
       {
         MutexLockerEx x(_indexedFreeListParLocks[cur_sz],
                         Mutex::_no_safepoint_check_flag);
         if (gfl->count() != 0) {
           // nn is the number of chunks of size cur_sz that
           // we'd need to split k-ways each, in order to create
           // "n" chunks of size word_sz each.
           const size_t nn = MAX2(n/k, (size_t)1);
           gfl->getFirstNChunksFromList(nn, &fl_for_cur_sz);
           found = true;
           if (k > 1) {
             // Update split death stats for the cur_sz-size blocks list:
             // we increment the split death count by the number of blocks
             // we just took from the cur_sz-size blocks list and which
             // we will be splitting below.
             ssize_t deaths = _indexedFreeList[cur_sz].splitDeaths() +
                              fl_for_cur_sz.count();
             _indexedFreeList[cur_sz].set_splitDeaths(deaths);
           }
         }
       }
       // Now transfer fl_for_cur_sz to fl.  Common case, we hope, is k = 1.
       if (found) {
         if (k == 1) {
           fl->prepend(&fl_for_cur_sz);
         } else {
           // Divide each block on fl_for_cur_sz up k ways.
           FreeChunk* fc;
           while ((fc = fl_for_cur_sz.getChunkAtHead()) != NULL) {
             // Must do this in reverse order, so that anybody attempting to
             // access the main chunk sees it as a single free block until we
             // change it.
             size_t fc_size = fc->size();
             for (int i = k-1; i >= 0; i--) {
               FreeChunk* ffc = (FreeChunk*)((HeapWord*)fc + i * word_sz);
               ffc->setSize(word_sz);
               ffc->linkNext(NULL);
               ffc->linkPrev(NULL); // Mark as a free block for other (parallel) GC threads.
               // Above must occur before BOT is updated below.
               // splitting from the right, fc_size == (k - i + 1) * wordsize
               _bt.mark_block((HeapWord*)ffc, word_sz);
               fc_size -= word_sz;
               _bt.verify_not_unallocated((HeapWord*)ffc, ffc->size());
               _bt.verify_single_block((HeapWord*)fc, fc_size);
               _bt.verify_single_block((HeapWord*)ffc, ffc->size());
               // Push this on "fl".
               fl->returnChunkAtHead(ffc);
             }
             // TRAP
             assert(fl->tail()->next() == NULL, "List invariant.");
           }
         }
         // Update birth stats for this block size.
         size_t num = fl->count();
         MutexLockerEx x(_indexedFreeListParLocks[word_sz],
                         Mutex::_no_safepoint_check_flag);
         ssize_t births = _indexedFreeList[word_sz].splitBirths() + num;
         _indexedFreeList[word_sz].set_splitBirths(births);
         return;
       }
     }
   }
   // Otherwise, we'll split a block from the dictionary.
   FreeChunk* fc = NULL;
   FreeChunk* rem_fc = NULL;
   size_t rem;
   {
     MutexLockerEx x(parDictionaryAllocLock(),
                     Mutex::_no_safepoint_check_flag);
     while (n > 0) {
       fc = dictionary()->getChunk(MAX2(n * word_sz,
                                   _dictionary->minSize()),
                                   FreeBlockDictionary::atLeast);
       if (fc != NULL) {
         _bt.allocated((HeapWord*)fc, fc->size());  // update _unallocated_blk
         dictionary()->dictCensusUpdate(fc->size(),
                                        true /*split*/,
                                        false /*birth*/);
         break;
       } else {
         n--;
       }
     }
     if (fc == NULL) return;
     assert((ssize_t)n >= 1, "Control point invariant");
     // Otherwise, split up that block.
     const size_t nn = fc->size() / word_sz;
     n = MIN2(nn, n);
     assert((ssize_t)n >= 1, "Control point invariant");
     rem = fc->size() - n * word_sz;
     // If there is a remainder, and it's too small, allocate one fewer.
     if (rem > 0 && rem < MinChunkSize) {
       n--; rem += word_sz;
     }
     // Note that at this point we may have n == 0.
     assert((ssize_t)n >= 0, "Control point invariant");
     // If n is 0, the chunk fc that was found is not large
     // enough to leave a viable remainder.  We are unable to
     // allocate even one block.  Return fc to the
     // dictionary and return, leaving "fl" empty.
     if (n == 0) {
       returnChunkToDictionary(fc);
       return;
     }
     // First return the remainder, if any.
     // Note that we hold the lock until we decide if we're going to give
     // back the remainder to the dictionary, since a concurrent allocation
     // may otherwise see the heap as empty.  (We're willing to take that
     // hit if the block is a small block.)
     if (rem > 0) {
       size_t prefix_size = n * word_sz;
       rem_fc = (FreeChunk*)((HeapWord*)fc + prefix_size);
       rem_fc->setSize(rem);
       rem_fc->linkNext(NULL);
       rem_fc->linkPrev(NULL); // Mark as a free block for other (parallel) GC threads.
       // Above must occur before BOT is updated below.
       assert((ssize_t)n > 0 && prefix_size > 0 && rem_fc > fc, "Error");
       _bt.split_block((HeapWord*)fc, fc->size(), prefix_size);
       if (rem >= IndexSetSize) {
         returnChunkToDictionary(rem_fc);
         dictionary()->dictCensusUpdate(rem, true /*split*/, true /*birth*/);
         rem_fc = NULL;
       }
       // Otherwise, return it to the small list below.
     }
   }
   if (rem_fc != NULL) {
     MutexLockerEx x(_indexedFreeListParLocks[rem],
                     Mutex::_no_safepoint_check_flag);
     _bt.verify_not_unallocated((HeapWord*)rem_fc, rem_fc->size());
     _indexedFreeList[rem].returnChunkAtHead(rem_fc);
     smallSplitBirth(rem);
   }
   assert((ssize_t)n > 0 && fc != NULL, "Consistency");
   // Now do the splitting up.
   // Must do this in reverse order, so that anybody attempting to
   // access the main chunk sees it as a single free block until we
   // change it.
   size_t fc_size = n * word_sz;
   // All but first chunk in this loop
   for (ssize_t i = n-1; i > 0; i--) {
     FreeChunk* ffc = (FreeChunk*)((HeapWord*)fc + i * word_sz);
     ffc->setSize(word_sz);
     ffc->linkNext(NULL);
     ffc->linkPrev(NULL); // Mark as a free block for other (parallel) GC threads.
     // Above must occur before BOT is updated below.
     // splitting from the right, fc_size == (n - i + 1) * wordsize
     _bt.mark_block((HeapWord*)ffc, word_sz);
     fc_size -= word_sz;
     _bt.verify_not_unallocated((HeapWord*)ffc, ffc->size());
     _bt.verify_single_block((HeapWord*)ffc, ffc->size());
     _bt.verify_single_block((HeapWord*)fc, fc_size);
     // Push this on "fl".
     fl->returnChunkAtHead(ffc);
   }
   // First chunk
   fc->setSize(word_sz);
   fc->linkNext(NULL);
   fc->linkPrev(NULL);
   _bt.verify_not_unallocated((HeapWord*)fc, fc->size());
   _bt.verify_single_block((HeapWord*)fc, fc->size());
   fl->returnChunkAtHead(fc);
   assert((ssize_t)n > 0 && (ssize_t)n == fl->count(), "Incorrect number of blocks");
   {
     // Update the stats for this block size.
     MutexLockerEx x(_indexedFreeListParLocks[word_sz],
                     Mutex::_no_safepoint_check_flag);
     const ssize_t births = _indexedFreeList[word_sz].splitBirths() + n;
     _indexedFreeList[word_sz].set_splitBirths(births);
     // ssize_t new_surplus = _indexedFreeList[word_sz].surplus() + n;
     // _indexedFreeList[word_sz].set_surplus(new_surplus);
   }
   // TRAP
   assert(fl->tail()->next() == NULL, "List invariant.");
 }
 // Set up the space's par_seq_tasks structure for work claiming
 // for parallel rescan. See CMSParRemarkTask where this is currently used.
 // XXX Need to suitably abstract and generalize this and the next
 // method into one.
 void
 CompactibleFreeListSpace::
 initialize_sequential_subtasks_for_rescan(int n_threads) {
   // The "size" of each task is fixed according to rescan_task_size.
   assert(n_threads > 0, "Unexpected n_threads argument");
   const size_t task_size = rescan_task_size();
   size_t n_tasks = (used_region().word_size() + task_size - 1)/task_size;
   assert((n_tasks == 0) == used_region().is_empty(), "n_tasks incorrect");
   assert(n_tasks == 0 ||
          ((used_region().start() + (n_tasks - 1)*task_size < used_region().end()) &&
           (used_region().start() + n_tasks*task_size >= used_region().end())),
          "n_tasks calculation incorrect");
   SequentialSubTasksDone* pst = conc_par_seq_tasks();
   assert(!pst->valid(), "Clobbering existing data?");
   pst->set_par_threads(n_threads);
   pst->set_n_tasks((int)n_tasks);
 }
 // Set up the space's par_seq_tasks structure for work claiming
 // for parallel concurrent marking. See CMSConcMarkTask where this is currently used.
 void
 CompactibleFreeListSpace::
 initialize_sequential_subtasks_for_marking(int n_threads,
                                            HeapWord* low) {
   // The "size" of each task is fixed according to rescan_task_size.
   assert(n_threads > 0, "Unexpected n_threads argument");
   const size_t task_size = marking_task_size();
   assert(task_size > CardTableModRefBS::card_size_in_words &&
          (task_size %  CardTableModRefBS::card_size_in_words == 0),
          "Otherwise arithmetic below would be incorrect");
   MemRegion span = _gen->reserved();
   if (low != NULL) {
     if (span.contains(low)) {
       // Align low down to  a card boundary so that
       // we can use block_offset_careful() on span boundaries.
       HeapWord* aligned_low = (HeapWord*)align_size_down((uintptr_t)low,
                                  CardTableModRefBS::card_size);
       // Clip span prefix at aligned_low
       span = span.intersection(MemRegion(aligned_low, span.end()));
     } else if (low > span.end()) {
       span = MemRegion(low, low);  // Null region
     } // else use entire span
   }
   assert(span.is_empty() ||
          ((uintptr_t)span.start() %  CardTableModRefBS::card_size == 0),
         "span should start at a card boundary");
   size_t n_tasks = (span.word_size() + task_size - 1)/task_size;
   assert((n_tasks == 0) == span.is_empty(), "Inconsistency");
   assert(n_tasks == 0 ||
          ((span.start() + (n_tasks - 1)*task_size < span.end()) &&
           (span.start() + n_tasks*task_size >= span.end())),
          "n_tasks calculation incorrect");
   SequentialSubTasksDone* pst = conc_par_seq_tasks();
   assert(!pst->valid(), "Clobbering existing data?");
   pst->set_par_threads(n_threads);
   pst->set_n_tasks((int)n_tasks);
 }

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.cpp@e9ff18c4ace7 (annotated)

src/share/vm/gc_implementation/concurrentMarkSweep/compactibleFreeListSpace.cpp