hotspot/src/share/vm/gc/cms/compactibleFreeListSpace.cpp
changeset 30764 fec48bf5a827
parent 30581 a91d6c47f076
child 30870 3050fdcdc60b
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/hotspot/src/share/vm/gc/cms/compactibleFreeListSpace.cpp	Wed May 13 15:16:06 2015 +0200
@@ -0,0 +1,3026 @@
+/*
+ * Copyright (c) 2001, 2015, 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 "precompiled.hpp"
+#include "gc/cms/cmsLockVerifier.hpp"
+#include "gc/cms/compactibleFreeListSpace.hpp"
+#include "gc/cms/concurrentMarkSweepGeneration.inline.hpp"
+#include "gc/cms/concurrentMarkSweepThread.hpp"
+#include "gc/shared/blockOffsetTable.inline.hpp"
+#include "gc/shared/collectedHeap.inline.hpp"
+#include "gc/shared/genCollectedHeap.hpp"
+#include "gc/shared/liveRange.hpp"
+#include "gc/shared/space.inline.hpp"
+#include "gc/shared/spaceDecorator.hpp"
+#include "memory/allocation.inline.hpp"
+#include "memory/resourceArea.hpp"
+#include "memory/universe.inline.hpp"
+#include "oops/oop.inline.hpp"
+#include "runtime/globals.hpp"
+#include "runtime/handles.inline.hpp"
+#include "runtime/init.hpp"
+#include "runtime/java.hpp"
+#include "runtime/orderAccess.inline.hpp"
+#include "runtime/vmThread.hpp"
+#include "utilities/copy.hpp"
+
+/////////////////////////////////////////////////////////////////////////
+//// CompactibleFreeListSpace
+/////////////////////////////////////////////////////////////////////////
+
+// highest ranked  free list lock rank
+int CompactibleFreeListSpace::_lockRank = Mutex::leaf + 3;
+
+// Defaults are 0 so things will break badly if incorrectly initialized.
+size_t CompactibleFreeListSpace::IndexSetStart  = 0;
+size_t CompactibleFreeListSpace::IndexSetStride = 0;
+
+size_t MinChunkSize = 0;
+
+void CompactibleFreeListSpace::set_cms_values() {
+  // Set CMS global values
+  assert(MinChunkSize == 0, "already set");
+
+  // MinChunkSize should be a multiple of MinObjAlignment and be large enough
+  // for chunks to contain a FreeChunk.
+  size_t min_chunk_size_in_bytes = align_size_up(sizeof(FreeChunk), MinObjAlignmentInBytes);
+  MinChunkSize = min_chunk_size_in_bytes / BytesPerWord;
+
+  assert(IndexSetStart == 0 && IndexSetStride == 0, "already set");
+  IndexSetStart  = MinChunkSize;
+  IndexSetStride = MinObjAlignment;
+}
+
+// Constructor
+CompactibleFreeListSpace::CompactibleFreeListSpace(BlockOffsetSharedArray* bs,
+  MemRegion mr, bool use_adaptive_freelists,
+  FreeBlockDictionary<FreeChunk>::DictionaryChoice dictionaryChoice) :
+  _dictionaryChoice(dictionaryChoice),
+  _adaptive_freelists(use_adaptive_freelists),
+  _bt(bs, mr),
+  // free list locks are in the range of values taken by _lockRank
+  // This range currently is [_leaf+2, _leaf+3]
+  // Note: this requires that CFLspace c'tors
+  // are called serially in the order in which the locks are
+  // are acquired in the program text. This is true today.
+  _freelistLock(_lockRank--, "CompactibleFreeListSpace._lock", true,
+                Monitor::_safepoint_check_sometimes),
+  _parDictionaryAllocLock(Mutex::leaf - 1,  // == rank(ExpandHeap_lock) - 1
+                          "CompactibleFreeListSpace._dict_par_lock", true,
+                          Monitor::_safepoint_check_never),
+  _rescan_task_size(CardTableModRefBS::card_size_in_words * BitsPerWord *
+                    CMSRescanMultiple),
+  _marking_task_size(CardTableModRefBS::card_size_in_words * BitsPerWord *
+                    CMSConcMarkMultiple),
+  _collector(NULL),
+  _preconsumptionDirtyCardClosure(NULL)
+{
+  assert(sizeof(FreeChunk) / BytesPerWord <= MinChunkSize,
+         "FreeChunk is larger than expected");
+  _bt.set_space(this);
+  initialize(mr, SpaceDecorator::Clear, SpaceDecorator::Mangle);
+  // We have all of "mr", all of which we place in the dictionary
+  // as one big chunk. We'll need to decide here which of several
+  // possible alternative dictionary implementations to use. For
+  // now the choice is easy, since we have only one working
+  // implementation, namely, the simple binary tree (splaying
+  // temporarily disabled).
+  switch (dictionaryChoice) {
+    case FreeBlockDictionary<FreeChunk>::dictionaryBinaryTree:
+      _dictionary = new AFLBinaryTreeDictionary(mr);
+      break;
+    case FreeBlockDictionary<FreeChunk>::dictionarySplayTree:
+    case FreeBlockDictionary<FreeChunk>::dictionarySkipList:
+    default:
+      warning("dictionaryChoice: selected option not understood; using"
+              " default BinaryTreeDictionary implementation instead.");
+  }
+  assert(_dictionary != NULL, "CMS dictionary initialization");
+  // The indexed free lists are initially all empty and are lazily
+  // filled in on demand. Initialize the array elements to NULL.
+  initializeIndexedFreeListArray();
+
+  // Not using adaptive free lists assumes that allocation is first
+  // from the linAB's.  Also a cms perm gen which can be compacted
+  // has to have the klass's klassKlass allocated at a lower
+  // address in the heap than the klass so that the klassKlass is
+  // moved to its new location before the klass is moved.
+  // Set the _refillSize for the linear allocation blocks
+  if (!use_adaptive_freelists) {
+    FreeChunk* fc = _dictionary->get_chunk(mr.word_size(),
+                                           FreeBlockDictionary<FreeChunk>::atLeast);
+    // The small linAB initially has all the space and will allocate
+    // a chunk of any size.
+    HeapWord* addr = (HeapWord*) fc;
+    _smallLinearAllocBlock.set(addr, fc->size() ,
+      1024*SmallForLinearAlloc, fc->size());
+    // Note that _unallocated_block is not updated here.
+    // Allocations from the linear allocation block should
+    // update it.
+  } else {
+    _smallLinearAllocBlock.set(0, 0, 1024*SmallForLinearAlloc,
+                               SmallForLinearAlloc);
+  }
+  // CMSIndexedFreeListReplenish should be at least 1
+  CMSIndexedFreeListReplenish = MAX2((uintx)1, CMSIndexedFreeListReplenish);
+  _promoInfo.setSpace(this);
+  if (UseCMSBestFit) {
+    _fitStrategy = FreeBlockBestFitFirst;
+  } else {
+    _fitStrategy = FreeBlockStrategyNone;
+  }
+  check_free_list_consistency();
+
+  // Initialize locks for parallel case.
+  for (size_t i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) {
+    _indexedFreeListParLocks[i] = new Mutex(Mutex::leaf - 1, // == ExpandHeap_lock - 1
+                                            "a freelist par lock", true, Mutex::_safepoint_check_sometimes);
+    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()->young_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");
+  }
+
+  compact_top += adjusted_size;
+
+  // we need to update the offset table so that the beginnings of objects can be
+  // found during scavenge.  Note that we are updating the offset table based on
+  // where the object will be once the compaction phase finishes.
+
+  // Always call cross_threshold().  A contiguous space can only call it when
+  // the compaction_top exceeds the current threshold but not for an
+  // non-contiguous space.
+  cp->threshold =
+    cp->space->cross_threshold(compact_top - adjusted_size, compact_top);
+  return compact_top;
+}
+
+// A modified copy of OffsetTableContigSpace::cross_threshold() with _offsets -> _bt
+// and use of single_block instead of alloc_block.  The name here is not really
+// appropriate - maybe a more general name could be invented for both the
+// contiguous and noncontiguous spaces.
+
+HeapWord* CompactibleFreeListSpace::cross_threshold(HeapWord* start, HeapWord* the_end) {
+  _bt.single_block(start, the_end);
+  return end();
+}
+
+// Initialize them to NULL.
+void CompactibleFreeListSpace::initializeIndexedFreeListArray() {
+  for (size_t i = 0; i < IndexSetSize; i++) {
+    // Note that on platforms where objects are double word aligned,
+    // the odd array elements are not used.  It is convenient, however,
+    // to map directly from the object size to the array element.
+    _indexedFreeList[i].reset(IndexSetSize);
+    _indexedFreeList[i].set_size(i);
+    assert(_indexedFreeList[i].count() == 0, "reset check failed");
+    assert(_indexedFreeList[i].head() == NULL, "reset check failed");
+    assert(_indexedFreeList[i].tail() == NULL, "reset check failed");
+    assert(_indexedFreeList[i].hint() == IndexSetSize, "reset check failed");
+  }
+}
+
+void CompactibleFreeListSpace::resetIndexedFreeListArray() {
+  for (size_t i = 1; i < IndexSetSize; i++) {
+    assert(_indexedFreeList[i].size() == (size_t) i,
+      "Indexed free list sizes are incorrect");
+    _indexedFreeList[i].reset(IndexSetSize);
+    assert(_indexedFreeList[i].count() == 0, "reset check failed");
+    assert(_indexedFreeList[i].head() == NULL, "reset check failed");
+    assert(_indexedFreeList[i].tail() == NULL, "reset check failed");
+    assert(_indexedFreeList[i].hint() == IndexSetSize, "reset check failed");
+  }
+}
+
+void CompactibleFreeListSpace::reset(MemRegion mr) {
+  resetIndexedFreeListArray();
+  dictionary()->reset();
+  if (BlockOffsetArrayUseUnallocatedBlock) {
+    assert(end() == mr.end(), "We are compacting to the bottom of CMS gen");
+    // Everything's allocated until proven otherwise.
+    _bt.set_unallocated_block(end());
+  }
+  if (!mr.is_empty()) {
+    assert(mr.word_size() >= MinChunkSize, "Chunk size is too small");
+    _bt.single_block(mr.start(), mr.word_size());
+    FreeChunk* fc = (FreeChunk*) mr.start();
+    fc->set_size(mr.word_size());
+    if (mr.word_size() >= IndexSetSize ) {
+      returnChunkToDictionary(fc);
+    } else {
+      _bt.verify_not_unallocated((HeapWord*)fc, fc->size());
+      _indexedFreeList[mr.word_size()].return_chunk_at_head(fc);
+    }
+    coalBirth(mr.word_size());
+  }
+  _promoInfo.reset();
+  _smallLinearAllocBlock._ptr = NULL;
+  _smallLinearAllocBlock._word_size = 0;
+}
+
+void CompactibleFreeListSpace::reset_after_compaction() {
+  // Reset the space to the new reality - one free chunk.
+  MemRegion mr(compaction_top(), end());
+  reset(mr);
+  // Now refill the linear allocation block(s) if possible.
+  if (_adaptive_freelists) {
+    refillLinearAllocBlocksIfNeeded();
+  } else {
+    // Place as much of mr in the linAB as we can get,
+    // provided it was big enough to go into the dictionary.
+    FreeChunk* fc = dictionary()->find_largest_dict();
+    if (fc != NULL) {
+      assert(fc->size() == mr.word_size(),
+             "Why was the chunk broken up?");
+      removeChunkFromDictionary(fc);
+      HeapWord* addr = (HeapWord*) fc;
+      _smallLinearAllocBlock.set(addr, fc->size() ,
+        1024*SmallForLinearAlloc, fc->size());
+      // Note that _unallocated_block is not updated here.
+    }
+  }
+}
+
+// Walks the entire dictionary, returning a coterminal
+// chunk, if it exists. Use with caution since it involves
+// a potentially complete walk of a potentially large tree.
+FreeChunk* CompactibleFreeListSpace::find_chunk_at_end() {
+
+  assert_lock_strong(&_freelistLock);
+
+  return dictionary()->find_chunk_ends_at(end());
+}
+
+
+#ifndef PRODUCT
+void CompactibleFreeListSpace::initializeIndexedFreeListArrayReturnedBytes() {
+  for (size_t i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) {
+    _indexedFreeList[i].allocation_stats()->set_returned_bytes(0);
+  }
+}
+
+size_t CompactibleFreeListSpace::sumIndexedFreeListArrayReturnedBytes() {
+  size_t sum = 0;
+  for (size_t i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) {
+    sum += _indexedFreeList[i].allocation_stats()->returned_bytes();
+  }
+  return sum;
+}
+
+size_t CompactibleFreeListSpace::totalCountInIndexedFreeLists() const {
+  size_t count = 0;
+  for (size_t i = IndexSetStart; i < IndexSetSize; i++) {
+    debug_only(
+      ssize_t total_list_count = 0;
+      for (FreeChunk* fc = _indexedFreeList[i].head(); fc != NULL;
+         fc = fc->next()) {
+        total_list_count++;
+      }
+      assert(total_list_count ==  _indexedFreeList[i].count(),
+        "Count in list is incorrect");
+    )
+    count += _indexedFreeList[i].count();
+  }
+  return count;
+}
+
+size_t CompactibleFreeListSpace::totalCount() {
+  size_t num = totalCountInIndexedFreeLists();
+  num +=  dictionary()->total_count();
+  if (_smallLinearAllocBlock._word_size != 0) {
+    num++;
+  }
+  return num;
+}
+#endif
+
+bool CompactibleFreeListSpace::is_free_block(const HeapWord* p) const {
+  FreeChunk* fc = (FreeChunk*) p;
+  return fc->is_free();
+}
+
+size_t CompactibleFreeListSpace::used() const {
+  return capacity() - free();
+}
+
+size_t CompactibleFreeListSpace::free() const {
+  // "MT-safe, but not MT-precise"(TM), if you will: i.e.
+  // if you do this while the structures are in flux you
+  // may get an approximate answer only; for instance
+  // because there is concurrent allocation either
+  // directly by mutators or for promotion during a GC.
+  // It's "MT-safe", however, in the sense that you are guaranteed
+  // not to crash and burn, for instance, because of walking
+  // pointers that could disappear as you were walking them.
+  // The approximation is because the various components
+  // that are read below are not read atomically (and
+  // further the computation of totalSizeInIndexedFreeLists()
+  // is itself a non-atomic computation. The normal use of
+  // this is during a resize operation at the end of GC
+  // and at that time you are guaranteed to get the
+  // correct actual value. However, for instance, this is
+  // also read completely asynchronously by the "perf-sampler"
+  // that supports jvmstat, and you are apt to see the values
+  // flicker in such cases.
+  assert(_dictionary != NULL, "No _dictionary?");
+  return (_dictionary->total_chunk_size(DEBUG_ONLY(freelistLock())) +
+          totalSizeInIndexedFreeLists() +
+          _smallLinearAllocBlock._word_size) * HeapWordSize;
+}
+
+size_t CompactibleFreeListSpace::max_alloc_in_words() const {
+  assert(_dictionary != NULL, "No _dictionary?");
+  assert_locked();
+  size_t res = _dictionary->max_chunk_size();
+  res = MAX2(res, MIN2(_smallLinearAllocBlock._word_size,
+                       (size_t) SmallForLinearAlloc - 1));
+  // XXX the following could potentially be pretty slow;
+  // should one, pessimistically for the rare cases when res
+  // calculated above is less than IndexSetSize,
+  // just return res calculated above? My reasoning was that
+  // those cases will be so rare that the extra time spent doesn't
+  // really matter....
+  // Note: do not change the loop test i >= res + IndexSetStride
+  // to i > res below, because i is unsigned and res may be zero.
+  for (size_t i = IndexSetSize - 1; i >= res + IndexSetStride;
+       i -= IndexSetStride) {
+    if (_indexedFreeList[i].head() != NULL) {
+      assert(_indexedFreeList[i].count() != 0, "Inconsistent FreeList");
+      return i;
+    }
+  }
+  return res;
+}
+
+void LinearAllocBlock::print_on(outputStream* st) const {
+  st->print_cr(" LinearAllocBlock: ptr = " PTR_FORMAT ", word_size = " SIZE_FORMAT
+            ", refillsize = " SIZE_FORMAT ", allocation_size_limit = " SIZE_FORMAT,
+            p2i(_ptr), _word_size, _refillSize, _allocation_size_limit);
+}
+
+void CompactibleFreeListSpace::print_on(outputStream* st) const {
+  st->print_cr("COMPACTIBLE FREELIST SPACE");
+  st->print_cr(" Space:");
+  Space::print_on(st);
+
+  st->print_cr("promoInfo:");
+  _promoInfo.print_on(st);
+
+  st->print_cr("_smallLinearAllocBlock");
+  _smallLinearAllocBlock.print_on(st);
+
+  // dump_memory_block(_smallLinearAllocBlock->_ptr, 128);
+
+  st->print_cr(" _fitStrategy = %s, _adaptive_freelists = %s",
+               _fitStrategy?"true":"false", _adaptive_freelists?"true":"false");
+}
+
+void CompactibleFreeListSpace::print_indexed_free_lists(outputStream* st)
+const {
+  reportIndexedFreeListStatistics();
+  gclog_or_tty->print_cr("Layout of Indexed Freelists");
+  gclog_or_tty->print_cr("---------------------------");
+  AdaptiveFreeList<FreeChunk>::print_labels_on(st, "size");
+  for (size_t i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) {
+    _indexedFreeList[i].print_on(gclog_or_tty);
+    for (FreeChunk* fc = _indexedFreeList[i].head(); fc != NULL;
+         fc = fc->next()) {
+      gclog_or_tty->print_cr("\t[" PTR_FORMAT "," PTR_FORMAT ")  %s",
+                          p2i(fc), p2i((HeapWord*)fc + i),
+                          fc->cantCoalesce() ? "\t CC" : "");
+    }
+  }
+}
+
+void CompactibleFreeListSpace::print_promo_info_blocks(outputStream* st)
+const {
+  _promoInfo.print_on(st);
+}
+
+void CompactibleFreeListSpace::print_dictionary_free_lists(outputStream* st)
+const {
+  _dictionary->report_statistics();
+  st->print_cr("Layout of Freelists in Tree");
+  st->print_cr("---------------------------");
+  _dictionary->print_free_lists(st);
+}
+
+class BlkPrintingClosure: public BlkClosure {
+  const CMSCollector*             _collector;
+  const CompactibleFreeListSpace* _sp;
+  const CMSBitMap*                _live_bit_map;
+  const bool                      _post_remark;
+  outputStream*                   _st;
+public:
+  BlkPrintingClosure(const CMSCollector* collector,
+                     const CompactibleFreeListSpace* sp,
+                     const CMSBitMap* live_bit_map,
+                     outputStream* st):
+    _collector(collector),
+    _sp(sp),
+    _live_bit_map(live_bit_map),
+    _post_remark(collector->abstract_state() > CMSCollector::FinalMarking),
+    _st(st) { }
+  size_t do_blk(HeapWord* addr);
+};
+
+size_t BlkPrintingClosure::do_blk(HeapWord* addr) {
+  size_t sz = _sp->block_size_no_stall(addr, _collector);
+  assert(sz != 0, "Should always be able to compute a size");
+  if (_sp->block_is_obj(addr)) {
+    const bool dead = _post_remark && !_live_bit_map->isMarked(addr);
+    _st->print_cr(PTR_FORMAT ": %s object of size " SIZE_FORMAT "%s",
+      p2i(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",
+      p2i(addr), sz, CMSPrintChunksInDump ? ":" : ".");
+    if (CMSPrintChunksInDump) {
+      ((FreeChunk*)addr)->print_on(_st);
+      _st->print_cr("--------------------------------------");
+    }
+  }
+  return sz;
+}
+
+void CompactibleFreeListSpace::dump_at_safepoint_with_locks(CMSCollector* c,
+  outputStream* st) {
+  st->print_cr("\n=========================");
+  st->print_cr("Block layout in CMS Heap:");
+  st->print_cr("=========================");
+  BlkPrintingClosure  bpcl(c, this, c->markBitMap(), st);
+  blk_iterate(&bpcl);
+
+  st->print_cr("\n=======================================");
+  st->print_cr("Order & Layout of Promotion Info Blocks");
+  st->print_cr("=======================================");
+  print_promo_info_blocks(st);
+
+  st->print_cr("\n===========================");
+  st->print_cr("Order of Indexed Free Lists");
+  st->print_cr("=========================");
+  print_indexed_free_lists(st);
+
+  st->print_cr("\n=================================");
+  st->print_cr("Order of Free Lists in Dictionary");
+  st->print_cr("=================================");
+  print_dictionary_free_lists(st);
+}
+
+
+void CompactibleFreeListSpace::reportFreeListStatistics() const {
+  assert_lock_strong(&_freelistLock);
+  assert(PrintFLSStatistics != 0, "Reporting error");
+  _dictionary->report_statistics();
+  if (PrintFLSStatistics > 1) {
+    reportIndexedFreeListStatistics();
+    size_t total_size = totalSizeInIndexedFreeLists() +
+                       _dictionary->total_chunk_size(DEBUG_ONLY(freelistLock()));
+    gclog_or_tty->print(" free=" SIZE_FORMAT " frag=%1.4f\n", total_size, flsFrag());
+  }
+}
+
+void CompactibleFreeListSpace::reportIndexedFreeListStatistics() const {
+  assert_lock_strong(&_freelistLock);
+  gclog_or_tty->print("Statistics for IndexedFreeLists:\n"
+                      "--------------------------------\n");
+  size_t total_size = totalSizeInIndexedFreeLists();
+  size_t   free_blocks = numFreeBlocksInIndexedFreeLists();
+  gclog_or_tty->print("Total Free Space: " SIZE_FORMAT "\n", total_size);
+  gclog_or_tty->print("Max   Chunk Size: " SIZE_FORMAT "\n", maxChunkSizeInIndexedFreeLists());
+  gclog_or_tty->print("Number of Blocks: " SIZE_FORMAT "\n", free_blocks);
+  if (free_blocks != 0) {
+    gclog_or_tty->print("Av.  Block  Size: " SIZE_FORMAT "\n", total_size/free_blocks);
+  }
+}
+
+size_t CompactibleFreeListSpace::numFreeBlocksInIndexedFreeLists() const {
+  size_t res = 0;
+  for (size_t i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) {
+    debug_only(
+      ssize_t recount = 0;
+      for (FreeChunk* fc = _indexedFreeList[i].head(); fc != NULL;
+         fc = fc->next()) {
+        recount += 1;
+      }
+      assert(recount == _indexedFreeList[i].count(),
+        "Incorrect count in list");
+    )
+    res += _indexedFreeList[i].count();
+  }
+  return res;
+}
+
+size_t CompactibleFreeListSpace::maxChunkSizeInIndexedFreeLists() const {
+  for (size_t i = IndexSetSize - 1; i != 0; i -= IndexSetStride) {
+    if (_indexedFreeList[i].head() != NULL) {
+      assert(_indexedFreeList[i].count() != 0, "Inconsistent FreeList");
+      return (size_t)i;
+    }
+  }
+  return 0;
+}
+
+void CompactibleFreeListSpace::set_end(HeapWord* value) {
+  HeapWord* prevEnd = end();
+  assert(prevEnd != value, "unnecessary set_end call");
+  assert(prevEnd == NULL || !BlockOffsetArrayUseUnallocatedBlock || value >= unallocated_block(),
+        "New end is below unallocated block");
+  _end = value;
+  if (prevEnd != NULL) {
+    // Resize the underlying block offset table.
+    _bt.resize(pointer_delta(value, bottom()));
+    if (value <= prevEnd) {
+      assert(!BlockOffsetArrayUseUnallocatedBlock || value >= unallocated_block(),
+             "New end is below unallocated block");
+    } else {
+      // Now, take this new chunk and add it to the free blocks.
+      // Note that the BOT has not yet been updated for this block.
+      size_t newFcSize = pointer_delta(value, prevEnd);
+      // XXX This is REALLY UGLY and should be fixed up. XXX
+      if (!_adaptive_freelists && _smallLinearAllocBlock._ptr == NULL) {
+        // Mark the boundary of the new block in BOT
+        _bt.mark_block(prevEnd, value);
+        // put it all in the linAB
+        MutexLockerEx x(parDictionaryAllocLock(),
+                        Mutex::_no_safepoint_check_flag);
+        _smallLinearAllocBlock._ptr = prevEnd;
+        _smallLinearAllocBlock._word_size = newFcSize;
+        repairLinearAllocBlock(&_smallLinearAllocBlock);
+        // Births of chunks put into a LinAB are not recorded.  Births
+        // of chunks as they are allocated out of a LinAB are.
+      } else {
+        // Add the block to the free lists, if possible coalescing it
+        // with the last free block, and update the BOT and census data.
+        addChunkToFreeListsAtEndRecordingStats(prevEnd, newFcSize);
+      }
+    }
+  }
+}
+
+class FreeListSpace_DCTOC : public Filtering_DCTOC {
+  CompactibleFreeListSpace* _cfls;
+  CMSCollector* _collector;
+protected:
+  // Override.
+#define walk_mem_region_with_cl_DECL(ClosureType)                       \
+  virtual void walk_mem_region_with_cl(MemRegion mr,                    \
+                                       HeapWord* bottom, HeapWord* top, \
+                                       ClosureType* cl);                \
+      void walk_mem_region_with_cl_par(MemRegion mr,                    \
+                                       HeapWord* bottom, HeapWord* top, \
+                                       ClosureType* cl);                \
+    void walk_mem_region_with_cl_nopar(MemRegion mr,                    \
+                                       HeapWord* bottom, HeapWord* top, \
+                                       ClosureType* cl)
+  walk_mem_region_with_cl_DECL(ExtendedOopClosure);
+  walk_mem_region_with_cl_DECL(FilteringClosure);
+
+public:
+  FreeListSpace_DCTOC(CompactibleFreeListSpace* sp,
+                      CMSCollector* collector,
+                      ExtendedOopClosure* cl,
+                      CardTableModRefBS::PrecisionStyle precision,
+                      HeapWord* boundary) :
+    Filtering_DCTOC(sp, cl, precision, boundary),
+    _cfls(sp), _collector(collector) {}
+};
+
+// We de-virtualize the block-related calls below, since we know that our
+// space is a CompactibleFreeListSpace.
+
+#define FreeListSpace_DCTOC__walk_mem_region_with_cl_DEFN(ClosureType)          \
+void FreeListSpace_DCTOC::walk_mem_region_with_cl(MemRegion mr,                 \
+                                                 HeapWord* bottom,              \
+                                                 HeapWord* top,                 \
+                                                 ClosureType* cl) {             \
+   bool is_par = GenCollectedHeap::heap()->n_par_threads() > 0;                 \
+   if (is_par) {                                                                \
+     assert(GenCollectedHeap::heap()->n_par_threads() ==                        \
+            GenCollectedHeap::heap()->workers()->active_workers(), "Mismatch"); \
+     walk_mem_region_with_cl_par(mr, bottom, top, cl);                          \
+   } else {                                                                     \
+     walk_mem_region_with_cl_nopar(mr, bottom, top, cl);                        \
+   }                                                                            \
+}                                                                               \
+void FreeListSpace_DCTOC::walk_mem_region_with_cl_par(MemRegion mr,             \
+                                                      HeapWord* bottom,         \
+                                                      HeapWord* top,            \
+                                                      ClosureType* cl) {        \
+  /* Skip parts that are before "mr", in case "block_start" sent us             \
+     back too far. */                                                           \
+  HeapWord* mr_start = mr.start();                                              \
+  size_t bot_size = _cfls->CompactibleFreeListSpace::block_size(bottom);        \
+  HeapWord* next = bottom + bot_size;                                           \
+  while (next < mr_start) {                                                     \
+    bottom = next;                                                              \
+    bot_size = _cfls->CompactibleFreeListSpace::block_size(bottom);             \
+    next = bottom + bot_size;                                                   \
+  }                                                                             \
+                                                                                \
+  while (bottom < top) {                                                        \
+    if (_cfls->CompactibleFreeListSpace::block_is_obj(bottom) &&                \
+        !_cfls->CompactibleFreeListSpace::obj_allocated_since_save_marks(       \
+                    oop(bottom)) &&                                             \
+        !_collector->CMSCollector::is_dead_obj(oop(bottom))) {                  \
+      size_t word_sz = oop(bottom)->oop_iterate(cl, mr);                        \
+      bottom += _cfls->adjustObjectSize(word_sz);                               \
+    } else {                                                                    \
+      bottom += _cfls->CompactibleFreeListSpace::block_size(bottom);            \
+    }                                                                           \
+  }                                                                             \
+}                                                                               \
+void FreeListSpace_DCTOC::walk_mem_region_with_cl_nopar(MemRegion mr,           \
+                                                        HeapWord* bottom,       \
+                                                        HeapWord* top,          \
+                                                        ClosureType* cl) {      \
+  /* Skip parts that are before "mr", in case "block_start" sent us             \
+     back too far. */                                                           \
+  HeapWord* mr_start = mr.start();                                              \
+  size_t bot_size = _cfls->CompactibleFreeListSpace::block_size_nopar(bottom);  \
+  HeapWord* next = bottom + bot_size;                                           \
+  while (next < mr_start) {                                                     \
+    bottom = next;                                                              \
+    bot_size = _cfls->CompactibleFreeListSpace::block_size_nopar(bottom);       \
+    next = bottom + bot_size;                                                   \
+  }                                                                             \
+                                                                                \
+  while (bottom < top) {                                                        \
+    if (_cfls->CompactibleFreeListSpace::block_is_obj_nopar(bottom) &&          \
+        !_cfls->CompactibleFreeListSpace::obj_allocated_since_save_marks(       \
+                    oop(bottom)) &&                                             \
+        !_collector->CMSCollector::is_dead_obj(oop(bottom))) {                  \
+      size_t word_sz = oop(bottom)->oop_iterate(cl, mr);                        \
+      bottom += _cfls->adjustObjectSize(word_sz);                               \
+    } else {                                                                    \
+      bottom += _cfls->CompactibleFreeListSpace::block_size_nopar(bottom);      \
+    }                                                                           \
+  }                                                                             \
+}
+
+// (There are only two of these, rather than N, because the split is due
+// only to the introduction of the FilteringClosure, a local part of the
+// impl of this abstraction.)
+FreeListSpace_DCTOC__walk_mem_region_with_cl_DEFN(ExtendedOopClosure)
+FreeListSpace_DCTOC__walk_mem_region_with_cl_DEFN(FilteringClosure)
+
+DirtyCardToOopClosure*
+CompactibleFreeListSpace::new_dcto_cl(ExtendedOopClosure* cl,
+                                      CardTableModRefBS::PrecisionStyle precision,
+                                      HeapWord* boundary) {
+  return new FreeListSpace_DCTOC(this, _collector, cl, precision, boundary);
+}
+
+
+// Note on locking for the space iteration functions:
+// since the collector's iteration activities are concurrent with
+// allocation activities by mutators, absent a suitable mutual exclusion
+// mechanism the iterators may go awry. For instance a block being iterated
+// may suddenly be allocated or divided up and part of it allocated and
+// so on.
+
+// Apply the given closure to each block in the space.
+void CompactibleFreeListSpace::blk_iterate_careful(BlkClosureCareful* cl) {
+  assert_lock_strong(freelistLock());
+  HeapWord *cur, *limit;
+  for (cur = bottom(), limit = end(); cur < limit;
+       cur += cl->do_blk_careful(cur));
+}
+
+// Apply the given closure to each block in the space.
+void CompactibleFreeListSpace::blk_iterate(BlkClosure* cl) {
+  assert_lock_strong(freelistLock());
+  HeapWord *cur, *limit;
+  for (cur = bottom(), limit = end(); cur < limit;
+       cur += cl->do_blk(cur));
+}
+
+// Apply the given closure to each oop in the space.
+void CompactibleFreeListSpace::oop_iterate(ExtendedOopClosure* cl) {
+  assert_lock_strong(freelistLock());
+  HeapWord *cur, *limit;
+  size_t curSize;
+  for (cur = bottom(), limit = end(); cur < limit;
+       cur += curSize) {
+    curSize = block_size(cur);
+    if (block_is_obj(cur)) {
+      oop(cur)->oop_iterate(cl);
+    }
+  }
+}
+
+// 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());
+  assert(!mr.is_empty(), "Should be non-empty");
+  // We use MemRegion(bottom(), end()) rather than used_region() below
+  // because the two are not necessarily equal for some kinds of
+  // spaces, in particular, certain kinds of free list spaces.
+  // We could use the more complicated but more precise:
+  // MemRegion(used_region().start(), round_to(used_region().end(), CardSize))
+  // but the slight imprecision seems acceptable in the assertion check.
+  assert(MemRegion(bottom(), end()).contains(mr),
+         "Should be within used space");
+  HeapWord* prev = cl->previous();   // max address from last time
+  if (prev >= mr.end()) { // nothing to do
+    return;
+  }
+  // This assert will not work when we go from cms space to perm
+  // space, and use same closure. Easy fix deferred for later. XXX YSR
+  // assert(prev == NULL || contains(prev), "Should be within space");
+
+  bool last_was_obj_array = false;
+  HeapWord *blk_start_addr, *region_start_addr;
+  if (prev > mr.start()) {
+    region_start_addr = prev;
+    blk_start_addr    = prev;
+    // The previous invocation may have pushed "prev" beyond the
+    // last allocated block yet there may be still be blocks
+    // in this region due to a particular coalescing policy.
+    // Relax the assertion so that the case where the unallocated
+    // block is maintained and "prev" is beyond the unallocated
+    // block does not cause the assertion to fire.
+    assert((BlockOffsetArrayUseUnallocatedBlock &&
+            (!is_in(prev))) ||
+           (blk_start_addr == block_start(region_start_addr)), "invariant");
+  } else {
+    region_start_addr = mr.start();
+    blk_start_addr    = block_start(region_start_addr);
+  }
+  HeapWord* region_end_addr = mr.end();
+  MemRegion derived_mr(region_start_addr, region_end_addr);
+  while (blk_start_addr < region_end_addr) {
+    const size_t size = block_size(blk_start_addr);
+    if (block_is_obj(blk_start_addr)) {
+      last_was_obj_array = cl->do_object_bm(oop(blk_start_addr), derived_mr);
+    } else {
+      last_was_obj_array = false;
+    }
+    blk_start_addr += size;
+  }
+  if (!last_was_obj_array) {
+    assert((bottom() <= blk_start_addr) && (blk_start_addr <= end()),
+           "Should be within (closed) used space");
+    assert(blk_start_addr > prev, "Invariant");
+    cl->set_previous(blk_start_addr); // min address for next time
+  }
+}
+
+// Callers of this iterator beware: The closure application should
+// be robust in the face of uninitialized objects and should (always)
+// return a correct size so that the next addr + size below gives us a
+// valid block boundary. [See for instance,
+// ScanMarkedObjectsAgainCarefullyClosure::do_object_careful()
+// in ConcurrentMarkSweepGeneration.cpp.]
+HeapWord*
+CompactibleFreeListSpace::object_iterate_careful_m(MemRegion mr,
+  ObjectClosureCareful* cl) {
+  assert_lock_strong(freelistLock());
+  // Can't use used_region() below because it may not necessarily
+  // be the same as [bottom(),end()); although we could
+  // use [used_region().start(),round_to(used_region().end(),CardSize)),
+  // that appears too cumbersome, so we just do the simpler check
+  // in the assertion below.
+  assert(!mr.is_empty() && MemRegion(bottom(),end()).contains(mr),
+         "mr should be non-empty and within used space");
+  HeapWord *addr, *end;
+  size_t size;
+  for (addr = block_start_careful(mr.start()), end  = mr.end();
+       addr < end; addr += size) {
+    FreeChunk* fc = (FreeChunk*)addr;
+    if (fc->is_free()) {
+      // Since we hold the free list lock, which protects direct
+      // allocation in this generation by mutators, a free object
+      // will remain free throughout this iteration code.
+      size = fc->size();
+    } else {
+      // Note that the object need not necessarily be initialized,
+      // because (for instance) the free list lock does NOT protect
+      // object initialization. The closure application below must
+      // therefore be correct in the face of uninitialized objects.
+      size = cl->do_object_careful_m(oop(addr), mr);
+      if (size == 0) {
+        // An unparsable object found. Signal early termination.
+        return addr;
+      }
+    }
+  }
+  return NULL;
+}
+
+
+HeapWord* CompactibleFreeListSpace::block_start_const(const void* p) const {
+  NOT_PRODUCT(verify_objects_initialized());
+  return _bt.block_start(p);
+}
+
+HeapWord* CompactibleFreeListSpace::block_start_careful(const void* p) const {
+  return _bt.block_start_careful(p);
+}
+
+size_t CompactibleFreeListSpace::block_size(const HeapWord* p) const {
+  NOT_PRODUCT(verify_objects_initialized());
+  // This must be volatile, or else there is a danger that the compiler
+  // will compile the code below into a sometimes-infinite loop, by keeping
+  // the value read the first time in a register.
+  while (true) {
+    // We must do this until we get a consistent view of the object.
+    if (FreeChunk::indicatesFreeChunk(p)) {
+      volatile FreeChunk* fc = (volatile FreeChunk*)p;
+      size_t res = fc->size();
+
+      // Bugfix for systems with weak memory model (PPC64/IA64). The
+      // block's free bit was set and we have read the size of the
+      // block. Acquire and check the free bit again. If the block is
+      // still free, the read size is correct.
+      OrderAccess::acquire();
+
+      // If the object is still a free chunk, return the size, else it
+      // has been allocated so try again.
+      if (FreeChunk::indicatesFreeChunk(p)) {
+        assert(res != 0, "Block size should not be 0");
+        return res;
+      }
+    } else {
+      // must read from what 'p' points to in each loop.
+      Klass* k = ((volatile oopDesc*)p)->klass_or_null();
+      if (k != NULL) {
+        assert(k->is_klass(), "Should really be klass oop.");
+        oop o = (oop)p;
+        assert(o->is_oop(true /* ignore mark word */), "Should be an oop.");
+
+        // Bugfix for systems with weak memory model (PPC64/IA64).
+        // The object o may be an array. Acquire to make sure that the array
+        // size (third word) is consistent.
+        OrderAccess::acquire();
+
+        size_t res = o->size_given_klass(k);
+        res = adjustObjectSize(res);
+        assert(res != 0, "Block size should not be 0");
+        return res;
+      }
+    }
+  }
+}
+
+// TODO: Now that is_parsable is gone, we should combine these two functions.
+// A variant of the above that uses the Printezis bits for
+// unparsable but allocated objects. This avoids any possible
+// stalls waiting for mutators to initialize objects, and is
+// thus potentially faster than the variant above. However,
+// this variant may return a zero size for a block that is
+// under mutation and for which a consistent size cannot be
+// inferred without stalling; see CMSCollector::block_size_if_printezis_bits().
+size_t CompactibleFreeListSpace::block_size_no_stall(HeapWord* p,
+                                                     const CMSCollector* c)
+const {
+  assert(MemRegion(bottom(), end()).contains(p), "p not in space");
+  // This must be volatile, or else there is a danger that the compiler
+  // will compile the code below into a sometimes-infinite loop, by keeping
+  // the value read the first time in a register.
+  DEBUG_ONLY(uint loops = 0;)
+  while (true) {
+    // We must do this until we get a consistent view of the object.
+    if (FreeChunk::indicatesFreeChunk(p)) {
+      volatile FreeChunk* fc = (volatile FreeChunk*)p;
+      size_t res = fc->size();
+
+      // Bugfix for systems with weak memory model (PPC64/IA64). The
+      // free bit of the block was set and we have read the size of
+      // the block. Acquire and check the free bit again. If the
+      // block is still free, the read size is correct.
+      OrderAccess::acquire();
+
+      if (FreeChunk::indicatesFreeChunk(p)) {
+        assert(res != 0, "Block size should not be 0");
+        assert(loops == 0, "Should be 0");
+        return res;
+      }
+    } else {
+      // must read from what 'p' points to in each loop.
+      Klass* k = ((volatile oopDesc*)p)->klass_or_null();
+      // We trust the size of any object that has a non-NULL
+      // klass and (for those in the perm gen) is parsable
+      // -- irrespective of its conc_safe-ty.
+      if (k != NULL) {
+        assert(k->is_klass(), "Should really be klass oop.");
+        oop o = (oop)p;
+        assert(o->is_oop(), "Should be an oop");
+
+        // Bugfix for systems with weak memory model (PPC64/IA64).
+        // The object o may be an array. Acquire to make sure that the array
+        // size (third word) is consistent.
+        OrderAccess::acquire();
+
+        size_t res = o->size_given_klass(k);
+        res = adjustObjectSize(res);
+        assert(res != 0, "Block size should not be 0");
+        return res;
+      } else {
+        // May return 0 if P-bits not present.
+        return c->block_size_if_printezis_bits(p);
+      }
+    }
+    assert(loops == 0, "Can loop at most once");
+    DEBUG_ONLY(loops++;)
+  }
+}
+
+size_t CompactibleFreeListSpace::block_size_nopar(const HeapWord* p) const {
+  NOT_PRODUCT(verify_objects_initialized());
+  assert(MemRegion(bottom(), end()).contains(p), "p not in space");
+  FreeChunk* fc = (FreeChunk*)p;
+  if (fc->is_free()) {
+    return fc->size();
+  } else {
+    // Ignore mark word because this may be a recently promoted
+    // object whose mark word is used to chain together grey
+    // objects (the last one would have a null value).
+    assert(oop(p)->is_oop(true), "Should be an oop");
+    return adjustObjectSize(oop(p)->size());
+  }
+}
+
+// This implementation assumes that the property of "being an object" is
+// stable.  But being a free chunk may not be (because of parallel
+// promotion.)
+bool CompactibleFreeListSpace::block_is_obj(const HeapWord* p) const {
+  FreeChunk* fc = (FreeChunk*)p;
+  assert(is_in_reserved(p), "Should be in space");
+  if (FreeChunk::indicatesFreeChunk(p)) return false;
+  Klass* k = oop(p)->klass_or_null();
+  if (k != NULL) {
+    // Ignore mark word because it may have been used to
+    // chain together promoted objects (the last one
+    // would have a null value).
+    assert(oop(p)->is_oop(true), "Should be an oop");
+    return true;
+  } else {
+    return false;  // Was not an object at the start of collection.
+  }
+}
+
+// Check if the object is alive. This fact is checked either by consulting
+// the main marking bitmap in the sweeping phase or, if it's a permanent
+// generation and we're not in the sweeping phase, by checking the
+// perm_gen_verify_bit_map where we store the "deadness" information if
+// we did not sweep the perm gen in the most recent previous GC cycle.
+bool CompactibleFreeListSpace::obj_is_alive(const HeapWord* p) const {
+  assert(SafepointSynchronize::is_at_safepoint() || !is_init_completed(),
+         "Else races are possible");
+  assert(block_is_obj(p), "The address should point to an object");
+
+  // If we're sweeping, we use object liveness information from the main bit map
+  // for both perm gen and old gen.
+  // We don't need to lock the bitmap (live_map or dead_map below), because
+  // EITHER we are in the middle of the sweeping phase, and the
+  // main marking bit map (live_map below) is locked,
+  // OR we're in other phases and perm_gen_verify_bit_map (dead_map below)
+  // is stable, because it's mutated only in the sweeping phase.
+  // NOTE: This method is also used by jmap where, if class unloading is
+  // off, the results can return "false" for legitimate perm objects,
+  // when we are not in the midst of a sweeping phase, which can result
+  // in jmap not reporting certain perm gen objects. This will be moot
+  // if/when the perm gen goes away in the future.
+  if (_collector->abstract_state() == CMSCollector::Sweeping) {
+    CMSBitMap* live_map = _collector->markBitMap();
+    return live_map->par_isMarked((HeapWord*) p);
+  }
+  return true;
+}
+
+bool CompactibleFreeListSpace::block_is_obj_nopar(const HeapWord* p) const {
+  FreeChunk* fc = (FreeChunk*)p;
+  assert(is_in_reserved(p), "Should be in space");
+  assert(_bt.block_start(p) == p, "Should be a block boundary");
+  if (!fc->is_free()) {
+    // Ignore mark word because it may have been used to
+    // chain together promoted objects (the last one
+    // would have a null value).
+    assert(oop(p)->is_oop(true), "Should be an oop");
+    return true;
+  }
+  return false;
+}
+
+// "MT-safe but not guaranteed MT-precise" (TM); you may get an
+// approximate answer if you don't hold the freelistlock when you call this.
+size_t CompactibleFreeListSpace::totalSizeInIndexedFreeLists() const {
+  size_t size = 0;
+  for (size_t i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) {
+    debug_only(
+      // We may be calling here without the lock in which case we
+      // won't do this modest sanity check.
+      if (freelistLock()->owned_by_self()) {
+        size_t total_list_size = 0;
+        for (FreeChunk* fc = _indexedFreeList[i].head(); fc != NULL;
+          fc = fc->next()) {
+          total_list_size += i;
+        }
+        assert(total_list_size == i * _indexedFreeList[i].count(),
+               "Count in list is incorrect");
+      }
+    )
+    size += i * _indexedFreeList[i].count();
+  }
+  return size;
+}
+
+HeapWord* CompactibleFreeListSpace::par_allocate(size_t size) {
+  MutexLockerEx x(freelistLock(), Mutex::_no_safepoint_check_flag);
+  return allocate(size);
+}
+
+HeapWord*
+CompactibleFreeListSpace::getChunkFromSmallLinearAllocBlockRemainder(size_t size) {
+  return getChunkFromLinearAllocBlockRemainder(&_smallLinearAllocBlock, size);
+}
+
+HeapWord* CompactibleFreeListSpace::allocate(size_t size) {
+  assert_lock_strong(freelistLock());
+  HeapWord* res = NULL;
+  assert(size == adjustObjectSize(size),
+         "use adjustObjectSize() before calling into allocate()");
+
+  if (_adaptive_freelists) {
+    res = allocate_adaptive_freelists(size);
+  } else {  // non-adaptive free lists
+    res = allocate_non_adaptive_freelists(size);
+  }
+
+  if (res != NULL) {
+    // check that res does lie in this space!
+    assert(is_in_reserved(res), "Not in this space!");
+    assert(is_aligned((void*)res), "alignment check");
+
+    FreeChunk* fc = (FreeChunk*)res;
+    fc->markNotFree();
+    assert(!fc->is_free(), "shouldn't be marked free");
+    assert(oop(fc)->klass_or_null() == NULL, "should look uninitialized");
+    // Verify that the block offset table shows this to
+    // be a single block, but not one which is unallocated.
+    _bt.verify_single_block(res, size);
+    _bt.verify_not_unallocated(res, size);
+    // mangle a just allocated object with a distinct pattern.
+    debug_only(fc->mangleAllocated(size));
+  }
+
+  return res;
+}
+
+HeapWord* CompactibleFreeListSpace::allocate_non_adaptive_freelists(size_t size) {
+  HeapWord* res = NULL;
+  // try and use linear allocation for smaller blocks
+  if (size < _smallLinearAllocBlock._allocation_size_limit) {
+    // if successful, the following also adjusts block offset table
+    res = getChunkFromSmallLinearAllocBlock(size);
+  }
+  // Else triage to indexed lists for smaller sizes
+  if (res == NULL) {
+    if (size < SmallForDictionary) {
+      res = (HeapWord*) getChunkFromIndexedFreeList(size);
+    } else {
+      // else get it from the big dictionary; if even this doesn't
+      // work we are out of luck.
+      res = (HeapWord*)getChunkFromDictionaryExact(size);
+    }
+  }
+
+  return res;
+}
+
+HeapWord* CompactibleFreeListSpace::allocate_adaptive_freelists(size_t size) {
+  assert_lock_strong(freelistLock());
+  HeapWord* res = NULL;
+  assert(size == adjustObjectSize(size),
+         "use adjustObjectSize() before calling into allocate()");
+
+  // Strategy
+  //   if small
+  //     exact size from small object indexed list if small
+  //     small or large linear allocation block (linAB) as appropriate
+  //     take from lists of greater sized chunks
+  //   else
+  //     dictionary
+  //     small or large linear allocation block if it has the space
+  // Try allocating exact size from indexTable first
+  if (size < IndexSetSize) {
+    res = (HeapWord*) getChunkFromIndexedFreeList(size);
+    if(res != NULL) {
+      assert(res != (HeapWord*)_indexedFreeList[size].head(),
+        "Not removed from free list");
+      // no block offset table adjustment is necessary on blocks in
+      // the indexed lists.
+
+    // Try allocating from the small LinAB
+    } else if (size < _smallLinearAllocBlock._allocation_size_limit &&
+        (res = getChunkFromSmallLinearAllocBlock(size)) != NULL) {
+        // if successful, the above also adjusts block offset table
+        // Note that this call will refill the LinAB to
+        // satisfy the request.  This is different that
+        // evm.
+        // Don't record chunk off a LinAB?  smallSplitBirth(size);
+    } else {
+      // Raid the exact free lists larger than size, even if they are not
+      // overpopulated.
+      res = (HeapWord*) getChunkFromGreater(size);
+    }
+  } else {
+    // Big objects get allocated directly from the dictionary.
+    res = (HeapWord*) getChunkFromDictionaryExact(size);
+    if (res == NULL) {
+      // Try hard not to fail since an allocation failure will likely
+      // trigger a synchronous GC.  Try to get the space from the
+      // allocation blocks.
+      res = getChunkFromSmallLinearAllocBlockRemainder(size);
+    }
+  }
+
+  return res;
+}
+
+// A worst-case estimate of the space required (in HeapWords) to expand the heap
+// when promoting obj.
+size_t CompactibleFreeListSpace::expansionSpaceRequired(size_t obj_size) const {
+  // Depending on the object size, expansion may require refilling either a
+  // bigLAB or a smallLAB plus refilling a PromotionInfo object.  MinChunkSize
+  // is added because the dictionary may over-allocate to avoid fragmentation.
+  size_t space = obj_size;
+  if (!_adaptive_freelists) {
+    space = MAX2(space, _smallLinearAllocBlock._refillSize);
+  }
+  space += _promoInfo.refillSize() + 2 * MinChunkSize;
+  return space;
+}
+
+FreeChunk* CompactibleFreeListSpace::getChunkFromGreater(size_t numWords) {
+  FreeChunk* ret;
+
+  assert(numWords >= MinChunkSize, "Size is less than minimum");
+  assert(linearAllocationWouldFail() || bestFitFirst(),
+    "Should not be here");
+
+  size_t i;
+  size_t currSize = numWords + MinChunkSize;
+  assert(currSize % MinObjAlignment == 0, "currSize should be aligned");
+  for (i = currSize; i < IndexSetSize; i += IndexSetStride) {
+    AdaptiveFreeList<FreeChunk>* fl = &_indexedFreeList[i];
+    if (fl->head()) {
+      ret = getFromListGreater(fl, numWords);
+      assert(ret == NULL || ret->is_free(), "Should be returning a free chunk");
+      return ret;
+    }
+  }
+
+  currSize = MAX2((size_t)SmallForDictionary,
+                  (size_t)(numWords + MinChunkSize));
+
+  /* Try to get a chunk that satisfies request, while avoiding
+     fragmentation that can't be handled. */
+  {
+    ret =  dictionary()->get_chunk(currSize);
+    if (ret != NULL) {
+      assert(ret->size() - numWords >= MinChunkSize,
+             "Chunk is too small");
+      _bt.allocated((HeapWord*)ret, ret->size());
+      /* Carve returned chunk. */
+      (void) splitChunkAndReturnRemainder(ret, numWords);
+      /* Label this as no longer a free chunk. */
+      assert(ret->is_free(), "This chunk should be free");
+      ret->link_prev(NULL);
+    }
+    assert(ret == NULL || ret->is_free(), "Should be returning a free chunk");
+    return ret;
+  }
+  ShouldNotReachHere();
+}
+
+bool CompactibleFreeListSpace::verifyChunkInIndexedFreeLists(FreeChunk* fc) const {
+  assert(fc->size() < IndexSetSize, "Size of chunk is too large");
+  return _indexedFreeList[fc->size()].verify_chunk_in_free_list(fc);
+}
+
+bool CompactibleFreeListSpace::verify_chunk_is_linear_alloc_block(FreeChunk* fc) const {
+  assert((_smallLinearAllocBlock._ptr != (HeapWord*)fc) ||
+         (_smallLinearAllocBlock._word_size == fc->size()),
+         "Linear allocation block shows incorrect size");
+  return ((_smallLinearAllocBlock._ptr == (HeapWord*)fc) &&
+          (_smallLinearAllocBlock._word_size == fc->size()));
+}
+
+// Check if the purported free chunk is present either as a linear
+// allocation block, the size-indexed table of (smaller) free blocks,
+// or the larger free blocks kept in the binary tree dictionary.
+bool CompactibleFreeListSpace::verify_chunk_in_free_list(FreeChunk* fc) const {
+  if (verify_chunk_is_linear_alloc_block(fc)) {
+    return true;
+  } else if (fc->size() < IndexSetSize) {
+    return verifyChunkInIndexedFreeLists(fc);
+  } else {
+    return dictionary()->verify_chunk_in_free_list(fc);
+  }
+}
+
+#ifndef PRODUCT
+void CompactibleFreeListSpace::assert_locked() const {
+  CMSLockVerifier::assert_locked(freelistLock(), parDictionaryAllocLock());
+}
+
+void CompactibleFreeListSpace::assert_locked(const Mutex* lock) const {
+  CMSLockVerifier::assert_locked(lock);
+}
+#endif
+
+FreeChunk* CompactibleFreeListSpace::allocateScratch(size_t size) {
+  // In the parallel case, the main thread holds the free list lock
+  // on behalf the parallel threads.
+  FreeChunk* fc;
+  {
+    // If GC is parallel, this might be called by several threads.
+    // This should be rare enough that the locking overhead won't affect
+    // the sequential code.
+    MutexLockerEx x(parDictionaryAllocLock(),
+                    Mutex::_no_safepoint_check_flag);
+    fc = getChunkFromDictionary(size);
+  }
+  if (fc != NULL) {
+    fc->dontCoalesce();
+    assert(fc->is_free(), "Should be free, but not coalescable");
+    // Verify that the block offset table shows this to
+    // be a single block, but not one which is unallocated.
+    _bt.verify_single_block((HeapWord*)fc, fc->size());
+    _bt.verify_not_unallocated((HeapWord*)fc, fc->size());
+  }
+  return fc;
+}
+
+oop CompactibleFreeListSpace::promote(oop obj, size_t obj_size) {
+  assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
+  assert_locked();
+
+  // if we are tracking promotions, then first ensure space for
+  // promotion (including spooling space for saving header if necessary).
+  // then allocate and copy, then track promoted info if needed.
+  // When tracking (see PromotionInfo::track()), the mark word may
+  // be displaced and in this case restoration of the mark word
+  // occurs in the (oop_since_save_marks_)iterate phase.
+  if (_promoInfo.tracking() && !_promoInfo.ensure_spooling_space()) {
+    return NULL;
+  }
+  // Call the allocate(size_t, bool) form directly to avoid the
+  // additional call through the allocate(size_t) form.  Having
+  // the compile inline the call is problematic because allocate(size_t)
+  // is a virtual method.
+  HeapWord* res = allocate(adjustObjectSize(obj_size));
+  if (res != NULL) {
+    Copy::aligned_disjoint_words((HeapWord*)obj, res, obj_size);
+    // if we should be tracking promotions, do so.
+    if (_promoInfo.tracking()) {
+        _promoInfo.track((PromotedObject*)res);
+    }
+  }
+  return oop(res);
+}
+
+HeapWord*
+CompactibleFreeListSpace::getChunkFromSmallLinearAllocBlock(size_t size) {
+  assert_locked();
+  assert(size >= MinChunkSize, "minimum chunk size");
+  assert(size <  _smallLinearAllocBlock._allocation_size_limit,
+    "maximum from smallLinearAllocBlock");
+  return getChunkFromLinearAllocBlock(&_smallLinearAllocBlock, size);
+}
+
+HeapWord*
+CompactibleFreeListSpace::getChunkFromLinearAllocBlock(LinearAllocBlock *blk,
+                                                       size_t size) {
+  assert_locked();
+  assert(size >= MinChunkSize, "too small");
+  HeapWord* res = NULL;
+  // Try to do linear allocation from blk, making sure that
+  if (blk->_word_size == 0) {
+    // We have probably been unable to fill this either in the prologue or
+    // when it was exhausted at the last linear allocation. Bail out until
+    // next time.
+    assert(blk->_ptr == NULL, "consistency check");
+    return NULL;
+  }
+  assert(blk->_word_size != 0 && blk->_ptr != NULL, "consistency check");
+  res = getChunkFromLinearAllocBlockRemainder(blk, size);
+  if (res != NULL) return res;
+
+  // about to exhaust this linear allocation block
+  if (blk->_word_size == size) { // exactly satisfied
+    res = blk->_ptr;
+    _bt.allocated(res, blk->_word_size);
+  } else if (size + MinChunkSize <= blk->_refillSize) {
+    size_t sz = blk->_word_size;
+    // Update _unallocated_block if the size is such that chunk would be
+    // returned to the indexed free list.  All other chunks in the indexed
+    // free lists are allocated from the dictionary so that _unallocated_block
+    // has already been adjusted for them.  Do it here so that the cost
+    // for all chunks added back to the indexed free lists.
+    if (sz < SmallForDictionary) {
+      _bt.allocated(blk->_ptr, sz);
+    }
+    // Return the chunk that isn't big enough, and then refill below.
+    addChunkToFreeLists(blk->_ptr, sz);
+    split_birth(sz);
+    // Don't keep statistics on adding back chunk from a LinAB.
+  } else {
+    // A refilled block would not satisfy the request.
+    return NULL;
+  }
+
+  blk->_ptr = NULL; blk->_word_size = 0;
+  refillLinearAllocBlock(blk);
+  assert(blk->_ptr == NULL || blk->_word_size >= size + MinChunkSize,
+         "block was replenished");
+  if (res != NULL) {
+    split_birth(size);
+    repairLinearAllocBlock(blk);
+  } else if (blk->_ptr != NULL) {
+    res = blk->_ptr;
+    size_t blk_size = blk->_word_size;
+    blk->_word_size -= size;
+    blk->_ptr  += size;
+    split_birth(size);
+    repairLinearAllocBlock(blk);
+    // Update BOT last so that other (parallel) GC threads see a consistent
+    // view of the BOT and free blocks.
+    // Above must occur before BOT is updated below.
+    OrderAccess::storestore();
+    _bt.split_block(res, blk_size, size);  // adjust block offset table
+  }
+  return res;
+}
+
+HeapWord*  CompactibleFreeListSpace::getChunkFromLinearAllocBlockRemainder(
+                                        LinearAllocBlock* blk,
+                                        size_t size) {
+  assert_locked();
+  assert(size >= MinChunkSize, "too small");
+
+  HeapWord* res = NULL;
+  // This is the common case.  Keep it simple.
+  if (blk->_word_size >= size + MinChunkSize) {
+    assert(blk->_ptr != NULL, "consistency check");
+    res = blk->_ptr;
+    // Note that the BOT is up-to-date for the linAB before allocation.  It
+    // indicates the start of the linAB.  The split_block() updates the
+    // BOT for the linAB after the allocation (indicates the start of the
+    // next chunk to be allocated).
+    size_t blk_size = blk->_word_size;
+    blk->_word_size -= size;
+    blk->_ptr  += size;
+    split_birth(size);
+    repairLinearAllocBlock(blk);
+    // Update BOT last so that other (parallel) GC threads see a consistent
+    // view of the BOT and free blocks.
+    // Above must occur before BOT is updated below.
+    OrderAccess::storestore();
+    _bt.split_block(res, blk_size, size);  // adjust block offset table
+    _bt.allocated(res, size);
+  }
+  return res;
+}
+
+FreeChunk*
+CompactibleFreeListSpace::getChunkFromIndexedFreeList(size_t size) {
+  assert_locked();
+  assert(size < SmallForDictionary, "just checking");
+  FreeChunk* res;
+  res = _indexedFreeList[size].get_chunk_at_head();
+  if (res == NULL) {
+    res = getChunkFromIndexedFreeListHelper(size);
+  }
+  _bt.verify_not_unallocated((HeapWord*) res, size);
+  assert(res == NULL || res->size() == size, "Incorrect block size");
+  return res;
+}
+
+FreeChunk*
+CompactibleFreeListSpace::getChunkFromIndexedFreeListHelper(size_t size,
+  bool replenish) {
+  assert_locked();
+  FreeChunk* fc = NULL;
+  if (size < SmallForDictionary) {
+    assert(_indexedFreeList[size].head() == NULL ||
+      _indexedFreeList[size].surplus() <= 0,
+      "List for this size should be empty or under populated");
+    // Try best fit in exact lists before replenishing the list
+    if (!bestFitFirst() || (fc = bestFitSmall(size)) == NULL) {
+      // Replenish list.
+      //
+      // Things tried that failed.
+      //   Tried allocating out of the two LinAB's first before
+      // replenishing lists.
+      //   Tried small linAB of size 256 (size in indexed list)
+      // and replenishing indexed lists from the small linAB.
+      //
+      FreeChunk* newFc = NULL;
+      const size_t replenish_size = CMSIndexedFreeListReplenish * size;
+      if (replenish_size < SmallForDictionary) {
+        // Do not replenish from an underpopulated size.
+        if (_indexedFreeList[replenish_size].surplus() > 0 &&
+            _indexedFreeList[replenish_size].head() != NULL) {
+          newFc = _indexedFreeList[replenish_size].get_chunk_at_head();
+        } else if (bestFitFirst()) {
+          newFc = bestFitSmall(replenish_size);
+        }
+      }
+      if (newFc == NULL && replenish_size > size) {
+        assert(CMSIndexedFreeListReplenish > 1, "ctl pt invariant");
+        newFc = getChunkFromIndexedFreeListHelper(replenish_size, false);
+      }
+      // Note: The stats update re split-death of block obtained above
+      // will be recorded below precisely when we know we are going to
+      // be actually splitting it into more than one pieces below.
+      if (newFc != NULL) {
+        if  (replenish || CMSReplenishIntermediate) {
+          // Replenish this list and return one block to caller.
+          size_t i;
+          FreeChunk *curFc, *nextFc;
+          size_t num_blk = newFc->size() / size;
+          assert(num_blk >= 1, "Smaller than requested?");
+          assert(newFc->size() % size == 0, "Should be integral multiple of request");
+          if (num_blk > 1) {
+            // we are sure we will be splitting the block just obtained
+            // into multiple pieces; record the split-death of the original
+            splitDeath(replenish_size);
+          }
+          // carve up and link blocks 0, ..., num_blk - 2
+          // The last chunk is not added to the lists but is returned as the
+          // free chunk.
+          for (curFc = newFc, nextFc = (FreeChunk*)((HeapWord*)curFc + size),
+               i = 0;
+               i < (num_blk - 1);
+               curFc = nextFc, nextFc = (FreeChunk*)((HeapWord*)nextFc + size),
+               i++) {
+            curFc->set_size(size);
+            // Don't record this as a return in order to try and
+            // determine the "returns" from a GC.
+            _bt.verify_not_unallocated((HeapWord*) fc, size);
+            _indexedFreeList[size].return_chunk_at_tail(curFc, false);
+            _bt.mark_block((HeapWord*)curFc, size);
+            split_birth(size);
+            // Don't record the initial population of the indexed list
+            // as a split birth.
+          }
+
+          // check that the arithmetic was OK above
+          assert((HeapWord*)nextFc == (HeapWord*)newFc + num_blk*size,
+            "inconsistency in carving newFc");
+          curFc->set_size(size);
+          _bt.mark_block((HeapWord*)curFc, size);
+          split_birth(size);
+          fc = curFc;
+        } else {
+          // Return entire block to caller
+          fc = newFc;
+        }
+      }
+    }
+  } else {
+    // Get a free chunk from the free chunk dictionary to be returned to
+    // replenish the indexed free list.
+    fc = getChunkFromDictionaryExact(size);
+  }
+  // assert(fc == NULL || fc->is_free(), "Should be returning a free chunk");
+  return fc;
+}
+
+FreeChunk*
+CompactibleFreeListSpace::getChunkFromDictionary(size_t size) {
+  assert_locked();
+  FreeChunk* fc = _dictionary->get_chunk(size,
+                                         FreeBlockDictionary<FreeChunk>::atLeast);
+  if (fc == NULL) {
+    return NULL;
+  }
+  _bt.allocated((HeapWord*)fc, fc->size());
+  if (fc->size() >= size + MinChunkSize) {
+    fc = splitChunkAndReturnRemainder(fc, size);
+  }
+  assert(fc->size() >= size, "chunk too small");
+  assert(fc->size() < size + MinChunkSize, "chunk too big");
+  _bt.verify_single_block((HeapWord*)fc, fc->size());
+  return fc;
+}
+
+FreeChunk*
+CompactibleFreeListSpace::getChunkFromDictionaryExact(size_t size) {
+  assert_locked();
+  FreeChunk* fc = _dictionary->get_chunk(size,
+                                         FreeBlockDictionary<FreeChunk>::atLeast);
+  if (fc == NULL) {
+    return fc;
+  }
+  _bt.allocated((HeapWord*)fc, fc->size());
+  if (fc->size() == size) {
+    _bt.verify_single_block((HeapWord*)fc, size);
+    return fc;
+  }
+  assert(fc->size() > size, "get_chunk() guarantee");
+  if (fc->size() < size + MinChunkSize) {
+    // Return the chunk to the dictionary and go get a bigger one.
+    returnChunkToDictionary(fc);
+    fc = _dictionary->get_chunk(size + MinChunkSize,
+                                FreeBlockDictionary<FreeChunk>::atLeast);
+    if (fc == NULL) {
+      return NULL;
+    }
+    _bt.allocated((HeapWord*)fc, fc->size());
+  }
+  assert(fc->size() >= size + MinChunkSize, "tautology");
+  fc = splitChunkAndReturnRemainder(fc, size);
+  assert(fc->size() == size, "chunk is wrong size");
+  _bt.verify_single_block((HeapWord*)fc, size);
+  return fc;
+}
+
+void
+CompactibleFreeListSpace::returnChunkToDictionary(FreeChunk* chunk) {
+  assert_locked();
+
+  size_t size = chunk->size();
+  _bt.verify_single_block((HeapWord*)chunk, size);
+  // adjust _unallocated_block downward, as necessary
+  _bt.freed((HeapWord*)chunk, size);
+  _dictionary->return_chunk(chunk);
+#ifndef PRODUCT
+  if (CMSCollector::abstract_state() != CMSCollector::Sweeping) {
+    TreeChunk<FreeChunk, AdaptiveFreeList<FreeChunk> >* tc = TreeChunk<FreeChunk, AdaptiveFreeList<FreeChunk> >::as_TreeChunk(chunk);
+    TreeList<FreeChunk, AdaptiveFreeList<FreeChunk> >* tl = tc->list();
+    tl->verify_stats();
+  }
+#endif // PRODUCT
+}
+
+void
+CompactibleFreeListSpace::returnChunkToFreeList(FreeChunk* fc) {
+  assert_locked();
+  size_t size = fc->size();
+  _bt.verify_single_block((HeapWord*) fc, size);
+  _bt.verify_not_unallocated((HeapWord*) fc, size);
+  if (_adaptive_freelists) {
+    _indexedFreeList[size].return_chunk_at_tail(fc);
+  } else {
+    _indexedFreeList[size].return_chunk_at_head(fc);
+  }
+#ifndef PRODUCT
+  if (CMSCollector::abstract_state() != CMSCollector::Sweeping) {
+     _indexedFreeList[size].verify_stats();
+  }
+#endif // PRODUCT
+}
+
+// Add chunk to end of last block -- if it's the largest
+// block -- and update BOT and census data. We would
+// of course have preferred to coalesce it with the
+// last block, but it's currently less expensive to find the
+// largest block than it is to find the last.
+void
+CompactibleFreeListSpace::addChunkToFreeListsAtEndRecordingStats(
+  HeapWord* chunk, size_t     size) {
+  // check that the chunk does lie in this space!
+  assert(chunk != NULL && is_in_reserved(chunk), "Not in this space!");
+  // One of the parallel gc task threads may be here
+  // whilst others are allocating.
+  Mutex* lock = &_parDictionaryAllocLock;
+  FreeChunk* ec;
+  {
+    MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
+    ec = dictionary()->find_largest_dict();  // get largest block
+    if (ec != NULL && ec->end() == (uintptr_t*) chunk) {
+      // It's a coterminal block - we can coalesce.
+      size_t old_size = ec->size();
+      coalDeath(old_size);
+      removeChunkFromDictionary(ec);
+      size += old_size;
+    } else {
+      ec = (FreeChunk*)chunk;
+    }
+  }
+  ec->set_size(size);
+  debug_only(ec->mangleFreed(size));
+  if (size < SmallForDictionary) {
+    lock = _indexedFreeListParLocks[size];
+  }
+  MutexLockerEx x(lock, Mutex::_no_safepoint_check_flag);
+  addChunkAndRepairOffsetTable((HeapWord*)ec, size, true);
+  // record the birth under the lock since the recording involves
+  // manipulation of the list on which the chunk lives and
+  // if the chunk is allocated and is the last on the list,
+  // the list can go away.
+  coalBirth(size);
+}
+
+void
+CompactibleFreeListSpace::addChunkToFreeLists(HeapWord* chunk,
+                                              size_t     size) {
+  // check that the chunk does lie in this space!
+  assert(chunk != NULL && is_in_reserved(chunk), "Not in this space!");
+  assert_locked();
+  _bt.verify_single_block(chunk, size);
+
+  FreeChunk* fc = (FreeChunk*) chunk;
+  fc->set_size(size);
+  debug_only(fc->mangleFreed(size));
+  if (size < SmallForDictionary) {
+    returnChunkToFreeList(fc);
+  } else {
+    returnChunkToDictionary(fc);
+  }
+}
+
+void
+CompactibleFreeListSpace::addChunkAndRepairOffsetTable(HeapWord* chunk,
+  size_t size, bool coalesced) {
+  assert_locked();
+  assert(chunk != NULL, "null chunk");
+  if (coalesced) {
+    // repair BOT
+    _bt.single_block(chunk, size);
+  }
+  addChunkToFreeLists(chunk, size);
+}
+
+// We _must_ find the purported chunk on our free lists;
+// we assert if we don't.
+void
+CompactibleFreeListSpace::removeFreeChunkFromFreeLists(FreeChunk* fc) {
+  size_t size = fc->size();
+  assert_locked();
+  debug_only(verifyFreeLists());
+  if (size < SmallForDictionary) {
+    removeChunkFromIndexedFreeList(fc);
+  } else {
+    removeChunkFromDictionary(fc);
+  }
+  _bt.verify_single_block((HeapWord*)fc, size);
+  debug_only(verifyFreeLists());
+}
+
+void
+CompactibleFreeListSpace::removeChunkFromDictionary(FreeChunk* fc) {
+  size_t size = fc->size();
+  assert_locked();
+  assert(fc != NULL, "null chunk");
+  _bt.verify_single_block((HeapWord*)fc, size);
+  _dictionary->remove_chunk(fc);
+  // adjust _unallocated_block upward, as necessary
+  _bt.allocated((HeapWord*)fc, size);
+}
+
+void
+CompactibleFreeListSpace::removeChunkFromIndexedFreeList(FreeChunk* fc) {
+  assert_locked();
+  size_t size = fc->size();
+  _bt.verify_single_block((HeapWord*)fc, size);
+  NOT_PRODUCT(
+    if (FLSVerifyIndexTable) {
+      verifyIndexedFreeList(size);
+    }
+  )
+  _indexedFreeList[size].remove_chunk(fc);
+  NOT_PRODUCT(
+    if (FLSVerifyIndexTable) {
+      verifyIndexedFreeList(size);
+    }
+  )
+}
+
+FreeChunk* CompactibleFreeListSpace::bestFitSmall(size_t numWords) {
+  /* A hint is the next larger size that has a surplus.
+     Start search at a size large enough to guarantee that
+     the excess is >= MIN_CHUNK. */
+  size_t start = align_object_size(numWords + MinChunkSize);
+  if (start < IndexSetSize) {
+    AdaptiveFreeList<FreeChunk>* it   = _indexedFreeList;
+    size_t    hint = _indexedFreeList[start].hint();
+    while (hint < IndexSetSize) {
+      assert(hint % MinObjAlignment == 0, "hint should be aligned");
+      AdaptiveFreeList<FreeChunk> *fl = &_indexedFreeList[hint];
+      if (fl->surplus() > 0 && fl->head() != NULL) {
+        // Found a list with surplus, reset original hint
+        // and split out a free chunk which is returned.
+        _indexedFreeList[start].set_hint(hint);
+        FreeChunk* res = getFromListGreater(fl, numWords);
+        assert(res == NULL || res->is_free(),
+          "Should be returning a free chunk");
+        return res;
+      }
+      hint = fl->hint(); /* keep looking */
+    }
+    /* None found. */
+    it[start].set_hint(IndexSetSize);
+  }
+  return NULL;
+}
+
+/* Requires fl->size >= numWords + MinChunkSize */
+FreeChunk* CompactibleFreeListSpace::getFromListGreater(AdaptiveFreeList<FreeChunk>* fl,
+  size_t numWords) {
+  FreeChunk *curr = fl->head();
+  size_t oldNumWords = curr->size();
+  assert(numWords >= MinChunkSize, "Word size is too small");
+  assert(curr != NULL, "List is empty");
+  assert(oldNumWords >= numWords + MinChunkSize,
+        "Size of chunks in the list is too small");
+
+  fl->remove_chunk(curr);
+  // recorded indirectly by splitChunkAndReturnRemainder -
+  // smallSplit(oldNumWords, numWords);
+  FreeChunk* new_chunk = splitChunkAndReturnRemainder(curr, numWords);
+  // Does anything have to be done for the remainder in terms of
+  // fixing the card table?
+  assert(new_chunk == NULL || new_chunk->is_free(),
+    "Should be returning a free chunk");
+  return new_chunk;
+}
+
+FreeChunk*
+CompactibleFreeListSpace::splitChunkAndReturnRemainder(FreeChunk* chunk,
+  size_t new_size) {
+  assert_locked();
+  size_t size = chunk->size();
+  assert(size > new_size, "Split from a smaller block?");
+  assert(is_aligned(chunk), "alignment problem");
+  assert(size == adjustObjectSize(size), "alignment problem");
+  size_t rem_sz = size - new_size;
+  assert(rem_sz == adjustObjectSize(rem_sz), "alignment problem");
+  assert(rem_sz >= MinChunkSize, "Free chunk smaller than minimum");
+  FreeChunk* ffc = (FreeChunk*)((HeapWord*)chunk + new_size);
+  assert(is_aligned(ffc), "alignment problem");
+  ffc->set_size(rem_sz);
+  ffc->link_next(NULL);
+  ffc->link_prev(NULL); // Mark as a free block for other (parallel) GC threads.
+  // Above must occur before BOT is updated below.
+  // adjust block offset table
+  OrderAccess::storestore();
+  assert(chunk->is_free() && ffc->is_free(), "Error");
+  _bt.split_block((HeapWord*)chunk, chunk->size(), new_size);
+  if (rem_sz < SmallForDictionary) {
+    bool is_par = (GenCollectedHeap::heap()->n_par_threads() > 0);
+    if (is_par) _indexedFreeListParLocks[rem_sz]->lock();
+    assert(!is_par ||
+           (GenCollectedHeap::heap()->n_par_threads() ==
+            GenCollectedHeap::heap()->workers()->active_workers()), "Mismatch");
+    returnChunkToFreeList(ffc);
+    split(size, rem_sz);
+    if (is_par) _indexedFreeListParLocks[rem_sz]->unlock();
+  } else {
+    returnChunkToDictionary(ffc);
+    split(size, rem_sz);
+  }
+  chunk->set_size(new_size);
+  return chunk;
+}
+
+void
+CompactibleFreeListSpace::sweep_completed() {
+  // Now that space is probably plentiful, refill linear
+  // allocation blocks as needed.
+  refillLinearAllocBlocksIfNeeded();
+}
+
+void
+CompactibleFreeListSpace::gc_prologue() {
+  assert_locked();
+  if (PrintFLSStatistics != 0) {
+    gclog_or_tty->print("Before GC:\n");
+    reportFreeListStatistics();
+  }
+  refillLinearAllocBlocksIfNeeded();
+}
+
+void
+CompactibleFreeListSpace::gc_epilogue() {
+  assert_locked();
+  if (PrintGCDetails && Verbose && !_adaptive_freelists) {
+    if (_smallLinearAllocBlock._word_size == 0)
+      warning("CompactibleFreeListSpace(epilogue):: Linear allocation failure");
+  }
+  assert(_promoInfo.noPromotions(), "_promoInfo inconsistency");
+  _promoInfo.stopTrackingPromotions();
+  repairLinearAllocationBlocks();
+  // Print Space's stats
+  if (PrintFLSStatistics != 0) {
+    gclog_or_tty->print("After GC:\n");
+    reportFreeListStatistics();
+  }
+}
+
+// Iteration support, mostly delegated from a CMS generation
+
+void CompactibleFreeListSpace::save_marks() {
+  assert(Thread::current()->is_VM_thread(),
+         "Global variable should only be set when single-threaded");
+  // Mark the "end" of the used space at the time of this call;
+  // note, however, that promoted objects from this point
+  // on are tracked in the _promoInfo below.
+  set_saved_mark_word(unallocated_block());
+#ifdef ASSERT
+  // Check the sanity of save_marks() etc.
+  MemRegion ur    = used_region();
+  MemRegion urasm = used_region_at_save_marks();
+  assert(ur.contains(urasm),
+         err_msg(" Error at save_marks(): [" PTR_FORMAT "," PTR_FORMAT ")"
+                 " should contain [" PTR_FORMAT "," PTR_FORMAT ")",
+                 p2i(ur.start()), p2i(ur.end()), p2i(urasm.start()), p2i(urasm.end())));
+#endif
+  // inform allocator that promotions should be tracked.
+  assert(_promoInfo.noPromotions(), "_promoInfo inconsistency");
+  _promoInfo.startTrackingPromotions();
+}
+
+bool CompactibleFreeListSpace::no_allocs_since_save_marks() {
+  assert(_promoInfo.tracking(), "No preceding save_marks?");
+  assert(GenCollectedHeap::heap()->n_par_threads() == 0,
+         "Shouldn't be called if using parallel gc.");
+  return _promoInfo.noPromotions();
+}
+
+#define CFLS_OOP_SINCE_SAVE_MARKS_DEFN(OopClosureType, nv_suffix)           \
+                                                                            \
+void CompactibleFreeListSpace::                                             \
+oop_since_save_marks_iterate##nv_suffix(OopClosureType* blk) {              \
+  assert(GenCollectedHeap::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)
+
+bool CompactibleFreeListSpace::linearAllocationWouldFail() const {
+  return _smallLinearAllocBlock._word_size == 0;
+}
+
+void CompactibleFreeListSpace::repairLinearAllocationBlocks() {
+  // Fix up linear allocation blocks to look like free blocks
+  repairLinearAllocBlock(&_smallLinearAllocBlock);
+}
+
+void CompactibleFreeListSpace::repairLinearAllocBlock(LinearAllocBlock* blk) {
+  assert_locked();
+  if (blk->_ptr != NULL) {
+    assert(blk->_word_size != 0 && blk->_word_size >= MinChunkSize,
+           "Minimum block size requirement");
+    FreeChunk* fc = (FreeChunk*)(blk->_ptr);
+    fc->set_size(blk->_word_size);
+    fc->link_prev(NULL);   // mark as free
+    fc->dontCoalesce();
+    assert(fc->is_free(), "just marked it free");
+    assert(fc->cantCoalesce(), "just marked it uncoalescable");
+  }
+}
+
+void CompactibleFreeListSpace::refillLinearAllocBlocksIfNeeded() {
+  assert_locked();
+  if (_smallLinearAllocBlock._ptr == NULL) {
+    assert(_smallLinearAllocBlock._word_size == 0,
+      "Size of linAB should be zero if the ptr is NULL");
+    // Reset the linAB refill and allocation size limit.
+    _smallLinearAllocBlock.set(0, 0, 1024*SmallForLinearAlloc, SmallForLinearAlloc);
+  }
+  refillLinearAllocBlockIfNeeded(&_smallLinearAllocBlock);
+}
+
+void
+CompactibleFreeListSpace::refillLinearAllocBlockIfNeeded(LinearAllocBlock* blk) {
+  assert_locked();
+  assert((blk->_ptr == NULL && blk->_word_size == 0) ||
+         (blk->_ptr != NULL && blk->_word_size >= MinChunkSize),
+         "blk invariant");
+  if (blk->_ptr == NULL) {
+    refillLinearAllocBlock(blk);
+  }
+  if (PrintMiscellaneous && Verbose) {
+    if (blk->_word_size == 0) {
+      warning("CompactibleFreeListSpace(prologue):: Linear allocation failure");
+    }
+  }
+}
+
+void
+CompactibleFreeListSpace::refillLinearAllocBlock(LinearAllocBlock* blk) {
+  assert_locked();
+  assert(blk->_word_size == 0 && blk->_ptr == NULL,
+         "linear allocation block should be empty");
+  FreeChunk* fc;
+  if (blk->_refillSize < SmallForDictionary &&
+      (fc = getChunkFromIndexedFreeList(blk->_refillSize)) != NULL) {
+    // A linAB's strategy might be to use small sizes to reduce
+    // fragmentation but still get the benefits of allocation from a
+    // linAB.
+  } else {
+    fc = getChunkFromDictionary(blk->_refillSize);
+  }
+  if (fc != NULL) {
+    blk->_ptr  = (HeapWord*)fc;
+    blk->_word_size = fc->size();
+    fc->dontCoalesce();   // to prevent sweeper from sweeping us up
+  }
+}
+
+// Support for concurrent collection policy decisions.
+bool CompactibleFreeListSpace::should_concurrent_collect() const {
+  // In the future we might want to add in fragmentation 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(this, cp);
+  // 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.
+}
+
+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(this);
+  // See note about verification in prepare_for_compaction().
+}
+
+void CompactibleFreeListSpace::compact() {
+  scan_and_compact(this);
+}
+
+// Fragmentation metric = 1 - [sum of (fbs**2) / (sum of fbs)**2]
+// where fbs is free block sizes
+double CompactibleFreeListSpace::flsFrag() const {
+  size_t itabFree = totalSizeInIndexedFreeLists();
+  double frag = 0.0;
+  size_t i;
+
+  for (i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) {
+    double sz  = i;
+    frag      += _indexedFreeList[i].count() * (sz * sz);
+  }
+
+  double totFree = itabFree +
+                   _dictionary->total_chunk_size(DEBUG_ONLY(freelistLock()));
+  if (totFree > 0) {
+    frag = ((frag + _dictionary->sum_of_squared_block_sizes()) /
+            (totFree * totFree));
+    frag = (double)1.0  - frag;
+  } else {
+    assert(frag == 0.0, "Follows from totFree == 0");
+  }
+  return frag;
+}
+
+void CompactibleFreeListSpace::beginSweepFLCensus(
+  float inter_sweep_current,
+  float inter_sweep_estimate,
+  float intra_sweep_estimate) {
+  assert_locked();
+  size_t i;
+  for (i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) {
+    AdaptiveFreeList<FreeChunk>* fl    = &_indexedFreeList[i];
+    if (PrintFLSStatistics > 1) {
+      gclog_or_tty->print("size[" SIZE_FORMAT "] : ", i);
+    }
+    fl->compute_desired(inter_sweep_current, inter_sweep_estimate, intra_sweep_estimate);
+    fl->set_coal_desired((ssize_t)((double)fl->desired() * CMSSmallCoalSurplusPercent));
+    fl->set_before_sweep(fl->count());
+    fl->set_bfr_surp(fl->surplus());
+  }
+  _dictionary->begin_sweep_dict_census(CMSLargeCoalSurplusPercent,
+                                    inter_sweep_current,
+                                    inter_sweep_estimate,
+                                    intra_sweep_estimate);
+}
+
+void CompactibleFreeListSpace::setFLSurplus() {
+  assert_locked();
+  size_t i;
+  for (i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) {
+    AdaptiveFreeList<FreeChunk> *fl = &_indexedFreeList[i];
+    fl->set_surplus(fl->count() -
+                    (ssize_t)((double)fl->desired() * CMSSmallSplitSurplusPercent));
+  }
+}
+
+void CompactibleFreeListSpace::setFLHints() {
+  assert_locked();
+  size_t i;
+  size_t h = IndexSetSize;
+  for (i = IndexSetSize - 1; i != 0; i -= IndexSetStride) {
+    AdaptiveFreeList<FreeChunk> *fl = &_indexedFreeList[i];
+    fl->set_hint(h);
+    if (fl->surplus() > 0) {
+      h = i;
+    }
+  }
+}
+
+void CompactibleFreeListSpace::clearFLCensus() {
+  assert_locked();
+  size_t i;
+  for (i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) {
+    AdaptiveFreeList<FreeChunk> *fl = &_indexedFreeList[i];
+    fl->set_prev_sweep(fl->count());
+    fl->set_coal_births(0);
+    fl->set_coal_deaths(0);
+    fl->set_split_births(0);
+    fl->set_split_deaths(0);
+  }
+}
+
+void CompactibleFreeListSpace::endSweepFLCensus(size_t sweep_count) {
+  if (PrintFLSStatistics > 0) {
+    HeapWord* largestAddr = (HeapWord*) dictionary()->find_largest_dict();
+    gclog_or_tty->print_cr("CMS: Large block " PTR_FORMAT,
+                           p2i(largestAddr));
+  }
+  setFLSurplus();
+  setFLHints();
+  if (PrintGC && PrintFLSCensus > 0) {
+    printFLCensus(sweep_count);
+  }
+  clearFLCensus();
+  assert_locked();
+  _dictionary->end_sweep_dict_census(CMSLargeSplitSurplusPercent);
+}
+
+bool CompactibleFreeListSpace::coalOverPopulated(size_t size) {
+  if (size < SmallForDictionary) {
+    AdaptiveFreeList<FreeChunk> *fl = &_indexedFreeList[size];
+    return (fl->coal_desired() < 0) ||
+           ((int)fl->count() > fl->coal_desired());
+  } else {
+    return dictionary()->coal_dict_over_populated(size);
+  }
+}
+
+void CompactibleFreeListSpace::smallCoalBirth(size_t size) {
+  assert(size < SmallForDictionary, "Size too large for indexed list");
+  AdaptiveFreeList<FreeChunk> *fl = &_indexedFreeList[size];
+  fl->increment_coal_births();
+  fl->increment_surplus();
+}
+
+void CompactibleFreeListSpace::smallCoalDeath(size_t size) {
+  assert(size < SmallForDictionary, "Size too large for indexed list");
+  AdaptiveFreeList<FreeChunk> *fl = &_indexedFreeList[size];
+  fl->increment_coal_deaths();
+  fl->decrement_surplus();
+}
+
+void CompactibleFreeListSpace::coalBirth(size_t size) {
+  if (size  < SmallForDictionary) {
+    smallCoalBirth(size);
+  } else {
+    dictionary()->dict_census_update(size,
+                                   false /* split */,
+                                   true /* birth */);
+  }
+}
+
+void CompactibleFreeListSpace::coalDeath(size_t size) {
+  if(size  < SmallForDictionary) {
+    smallCoalDeath(size);
+  } else {
+    dictionary()->dict_census_update(size,
+                                   false /* split */,
+                                   false /* birth */);
+  }
+}
+
+void CompactibleFreeListSpace::smallSplitBirth(size_t size) {
+  assert(size < SmallForDictionary, "Size too large for indexed list");
+  AdaptiveFreeList<FreeChunk> *fl = &_indexedFreeList[size];
+  fl->increment_split_births();
+  fl->increment_surplus();
+}
+
+void CompactibleFreeListSpace::smallSplitDeath(size_t size) {
+  assert(size < SmallForDictionary, "Size too large for indexed list");
+  AdaptiveFreeList<FreeChunk> *fl = &_indexedFreeList[size];
+  fl->increment_split_deaths();
+  fl->decrement_surplus();
+}
+
+void CompactibleFreeListSpace::split_birth(size_t size) {
+  if (size  < SmallForDictionary) {
+    smallSplitBirth(size);
+  } else {
+    dictionary()->dict_census_update(size,
+                                   true /* split */,
+                                   true /* birth */);
+  }
+}
+
+void CompactibleFreeListSpace::splitDeath(size_t size) {
+  if (size  < SmallForDictionary) {
+    smallSplitDeath(size);
+  } else {
+    dictionary()->dict_census_update(size,
+                                   true /* split */,
+                                   false /* birth */);
+  }
+}
+
+void CompactibleFreeListSpace::split(size_t from, size_t to1) {
+  size_t to2 = from - to1;
+  splitDeath(from);
+  split_birth(to1);
+  split_birth(to2);
+}
+
+void CompactibleFreeListSpace::print() const {
+  print_on(tty);
+}
+
+void CompactibleFreeListSpace::prepare_for_verify() {
+  assert_locked();
+  repairLinearAllocationBlocks();
+  // Verify that the SpoolBlocks look like free blocks of
+  // appropriate sizes... To be done ...
+}
+
+class VerifyAllBlksClosure: public BlkClosure {
+ private:
+  const CompactibleFreeListSpace* _sp;
+  const MemRegion                 _span;
+  HeapWord*                       _last_addr;
+  size_t                          _last_size;
+  bool                            _last_was_obj;
+  bool                            _last_was_live;
+
+ public:
+  VerifyAllBlksClosure(const CompactibleFreeListSpace* sp,
+    MemRegion span) :  _sp(sp), _span(span),
+                       _last_addr(NULL), _last_size(0),
+                       _last_was_obj(false), _last_was_live(false) { }
+
+  virtual size_t do_blk(HeapWord* addr) {
+    size_t res;
+    bool   was_obj  = false;
+    bool   was_live = false;
+    if (_sp->block_is_obj(addr)) {
+      was_obj = true;
+      oop p = oop(addr);
+      guarantee(p->is_oop(), "Should be an oop");
+      res = _sp->adjustObjectSize(p->size());
+      if (_sp->obj_is_alive(addr)) {
+        was_live = true;
+        p->verify();
+      }
+    } else {
+      FreeChunk* fc = (FreeChunk*)addr;
+      res = fc->size();
+      if (FLSVerifyLists && !fc->cantCoalesce()) {
+        guarantee(_sp->verify_chunk_in_free_list(fc),
+                  "Chunk should be on a free list");
+      }
+    }
+    if (res == 0) {
+      gclog_or_tty->print_cr("Livelock: no rank reduction!");
+      gclog_or_tty->print_cr(
+        " Current:  addr = " PTR_FORMAT ", size = " SIZE_FORMAT ", obj = %s, live = %s \n"
+        " Previous: addr = " PTR_FORMAT ", size = " SIZE_FORMAT ", obj = %s, live = %s \n",
+        p2i(addr),       res,        was_obj      ?"true":"false", was_live      ?"true":"false",
+        p2i(_last_addr), _last_size, _last_was_obj?"true":"false", _last_was_live?"true":"false");
+      _sp->print_on(gclog_or_tty);
+      guarantee(false, "Seppuku!");
+    }
+    _last_addr = addr;
+    _last_size = res;
+    _last_was_obj  = was_obj;
+    _last_was_live = was_live;
+    return res;
+  }
+};
+
+class VerifyAllOopsClosure: public OopClosure {
+ private:
+  const CMSCollector*             _collector;
+  const CompactibleFreeListSpace* _sp;
+  const MemRegion                 _span;
+  const bool                      _past_remark;
+  const CMSBitMap*                _bit_map;
+
+ protected:
+  void do_oop(void* p, oop obj) {
+    if (_span.contains(obj)) { // the interior oop points into CMS heap
+      if (!_span.contains(p)) { // reference from outside CMS heap
+        // Should be a valid object; the first disjunct below allows
+        // us to sidestep an assertion in block_is_obj() that insists
+        // that p be in _sp. Note that several generations (and spaces)
+        // are spanned by _span (CMS heap) above.
+        guarantee(!_sp->is_in_reserved(obj) ||
+                  _sp->block_is_obj((HeapWord*)obj),
+                  "Should be an object");
+        guarantee(obj->is_oop(), "Should be an oop");
+        obj->verify();
+        if (_past_remark) {
+          // Remark has been completed, the object should be marked
+          _bit_map->isMarked((HeapWord*)obj);
+        }
+      } else { // reference within CMS heap
+        if (_past_remark) {
+          // Remark has been completed -- so the referent should have
+          // been marked, if referring object is.
+          if (_bit_map->isMarked(_collector->block_start(p))) {
+            guarantee(_bit_map->isMarked((HeapWord*)obj), "Marking error?");
+          }
+        }
+      }
+    } else if (_sp->is_in_reserved(p)) {
+      // the reference is from FLS, and points out of FLS
+      guarantee(obj->is_oop(), "Should be an oop");
+      obj->verify();
+    }
+  }
+
+  template <class T> void do_oop_work(T* p) {
+    T heap_oop = oopDesc::load_heap_oop(p);
+    if (!oopDesc::is_null(heap_oop)) {
+      oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
+      do_oop(p, obj);
+    }
+  }
+
+ public:
+  VerifyAllOopsClosure(const CMSCollector* collector,
+    const CompactibleFreeListSpace* sp, MemRegion span,
+    bool past_remark, CMSBitMap* bit_map) :
+    _collector(collector), _sp(sp), _span(span),
+    _past_remark(past_remark), _bit_map(bit_map) { }
+
+  virtual void do_oop(oop* p)       { VerifyAllOopsClosure::do_oop_work(p); }
+  virtual void do_oop(narrowOop* p) { VerifyAllOopsClosure::do_oop_work(p); }
+};
+
+void CompactibleFreeListSpace::verify() const {
+  assert_lock_strong(&_freelistLock);
+  verify_objects_initialized();
+  MemRegion span = _collector->_span;
+  bool past_remark = (_collector->abstract_state() ==
+                      CMSCollector::Sweeping);
+
+  ResourceMark rm;
+  HandleMark  hm;
+
+  // Check integrity of CFL data structures
+  _promoInfo.verify();
+  _dictionary->verify();
+  if (FLSVerifyIndexTable) {
+    verifyIndexedFreeLists();
+  }
+  // Check integrity of all objects and free blocks in space
+  {
+    VerifyAllBlksClosure cl(this, span);
+    ((CompactibleFreeListSpace*)this)->blk_iterate(&cl);  // cast off const
+  }
+  // Check that all references in the heap to FLS
+  // are to valid objects in FLS or that references in
+  // FLS are to valid objects elsewhere in the heap
+  if (FLSVerifyAllHeapReferences)
+  {
+    VerifyAllOopsClosure cl(_collector, this, span, past_remark,
+      _collector->markBitMap());
+
+    // Iterate over all oops in the heap. Uses the _no_header version
+    // since we are not interested in following the klass pointers.
+    GenCollectedHeap::heap()->oop_iterate_no_header(&cl);
+  }
+
+  if (VerifyObjectStartArray) {
+    // Verify the block offset table
+    _bt.verify();
+  }
+}
+
+#ifndef PRODUCT
+void CompactibleFreeListSpace::verifyFreeLists() const {
+  if (FLSVerifyLists) {
+    _dictionary->verify();
+    verifyIndexedFreeLists();
+  } else {
+    if (FLSVerifyDictionary) {
+      _dictionary->verify();
+    }
+    if (FLSVerifyIndexTable) {
+      verifyIndexedFreeLists();
+    }
+  }
+}
+#endif
+
+void CompactibleFreeListSpace::verifyIndexedFreeLists() const {
+  size_t i = 0;
+  for (; i < IndexSetStart; i++) {
+    guarantee(_indexedFreeList[i].head() == NULL, "should be NULL");
+  }
+  for (; i < IndexSetSize; i++) {
+    verifyIndexedFreeList(i);
+  }
+}
+
+void CompactibleFreeListSpace::verifyIndexedFreeList(size_t size) const {
+  FreeChunk* fc   =  _indexedFreeList[size].head();
+  FreeChunk* tail =  _indexedFreeList[size].tail();
+  size_t    num = _indexedFreeList[size].count();
+  size_t      n = 0;
+  guarantee(((size >= IndexSetStart) && (size % IndexSetStride == 0)) || fc == NULL,
+            "Slot should have been empty");
+  for (; fc != NULL; fc = fc->next(), n++) {
+    guarantee(fc->size() == size, "Size inconsistency");
+    guarantee(fc->is_free(), "!free?");
+    guarantee(fc->next() == NULL || fc->next()->prev() == fc, "Broken list");
+    guarantee((fc->next() == NULL) == (fc == tail), "Incorrect tail");
+  }
+  guarantee(n == num, "Incorrect count");
+}
+
+#ifndef PRODUCT
+void CompactibleFreeListSpace::check_free_list_consistency() const {
+  assert((TreeChunk<FreeChunk, AdaptiveFreeList<FreeChunk> >::min_size() <= IndexSetSize),
+    "Some sizes can't be allocated without recourse to"
+    " linear allocation buffers");
+  assert((TreeChunk<FreeChunk, AdaptiveFreeList<FreeChunk> >::min_size()*HeapWordSize == sizeof(TreeChunk<FreeChunk, AdaptiveFreeList<FreeChunk> >)),
+    "else MIN_TREE_CHUNK_SIZE is wrong");
+  assert(IndexSetStart != 0, "IndexSetStart not initialized");
+  assert(IndexSetStride != 0, "IndexSetStride not initialized");
+}
+#endif
+
+void CompactibleFreeListSpace::printFLCensus(size_t sweep_count) const {
+  assert_lock_strong(&_freelistLock);
+  AdaptiveFreeList<FreeChunk> total;
+  gclog_or_tty->print("end sweep# " SIZE_FORMAT "\n", sweep_count);
+  AdaptiveFreeList<FreeChunk>::print_labels_on(gclog_or_tty, "size");
+  size_t total_free = 0;
+  for (size_t i = IndexSetStart; i < IndexSetSize; i += IndexSetStride) {
+    const AdaptiveFreeList<FreeChunk> *fl = &_indexedFreeList[i];
+    total_free += fl->count() * fl->size();
+    if (i % (40*IndexSetStride) == 0) {
+      AdaptiveFreeList<FreeChunk>::print_labels_on(gclog_or_tty, "size");
+    }
+    fl->print_on(gclog_or_tty);
+    total.set_bfr_surp(    total.bfr_surp()     + fl->bfr_surp()    );
+    total.set_surplus(    total.surplus()     + fl->surplus()    );
+    total.set_desired(    total.desired()     + fl->desired()    );
+    total.set_prev_sweep(  total.prev_sweep()   + fl->prev_sweep()  );
+    total.set_before_sweep(total.before_sweep() + fl->before_sweep());
+    total.set_count(      total.count()       + fl->count()      );
+    total.set_coal_births( total.coal_births()  + fl->coal_births() );
+    total.set_coal_deaths( total.coal_deaths()  + fl->coal_deaths() );
+    total.set_split_births(total.split_births() + fl->split_births());
+    total.set_split_deaths(total.split_deaths() + fl->split_deaths());
+  }
+  total.print_on(gclog_or_tty, "TOTAL");
+  gclog_or_tty->print_cr("Total free in indexed lists "
+                         SIZE_FORMAT " words", total_free);
+  gclog_or_tty->print("growth: %8.5f  deficit: %8.5f\n",
+    (double)(total.split_births()+total.coal_births()-total.split_deaths()-total.coal_deaths())/
+            (total.prev_sweep() != 0 ? (double)total.prev_sweep() : 1.0),
+    (double)(total.desired() - total.count())/(total.desired() != 0 ? (double)total.desired() : 1.0));
+  _dictionary->print_dict_census();
+}
+
+///////////////////////////////////////////////////////////////////////////
+// CFLS_LAB
+///////////////////////////////////////////////////////////////////////////
+
+#define VECTOR_257(x)                                                                                  \
+  /* 1  2  3  4  5  6  7  8  9 1x 11 12 13 14 15 16 17 18 19 2x 21 22 23 24 25 26 27 28 29 3x 31 32 */ \
+  {  x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x,   \
+     x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x,   \
+     x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x,   \
+     x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x,   \
+     x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x,   \
+     x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x,   \
+     x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x,   \
+     x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x,   \
+     x }
+
+// Initialize with default setting for CMS, _not_
+// generic 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)CFLS_LAB::_default_dynamic_old_plab_size));
+size_t CFLS_LAB::_global_num_blocks[]  = VECTOR_257(0);
+uint   CFLS_LAB::_global_num_workers[] = VECTOR_257(0);
+
+CFLS_LAB::CFLS_LAB(CompactibleFreeListSpace* cfls) :
+  _cfls(cfls)
+{
+  assert(CompactibleFreeListSpace::IndexSetSize == 257, "Modify VECTOR_257() macro above");
+  for (size_t i = CompactibleFreeListSpace::IndexSetStart;
+       i < CompactibleFreeListSpace::IndexSetSize;
+       i += CompactibleFreeListSpace::IndexSetStride) {
+    _indexedFreeList[i].set_size(i);
+    _num_blocks[i] = 0;
+  }
+}
+
+static bool _CFLS_LAB_modified = false;
+
+void CFLS_LAB::modify_initialization(size_t n, unsigned wt) {
+  assert(!_CFLS_LAB_modified, "Call only once");
+  _CFLS_LAB_modified = true;
+  for (size_t i = CompactibleFreeListSpace::IndexSetStart;
+       i < CompactibleFreeListSpace::IndexSetSize;
+       i += CompactibleFreeListSpace::IndexSetStride) {
+    _blocks_to_claim[i].modify(n, wt, true /* force */);
+  }
+}
+
+HeapWord* CFLS_LAB::alloc(size_t word_sz) {
+  FreeChunk* res;
+  assert(word_sz == _cfls->adjustObjectSize(word_sz), "Error");
+  if (word_sz >=  CompactibleFreeListSpace::IndexSetSize) {
+    // This locking manages sync with other large object allocations.
+    MutexLockerEx x(_cfls->parDictionaryAllocLock(),
+                    Mutex::_no_safepoint_check_flag);
+    res = _cfls->getChunkFromDictionaryExact(word_sz);
+    if (res == NULL) return NULL;
+  } else {
+    AdaptiveFreeList<FreeChunk>* fl = &_indexedFreeList[word_sz];
+    if (fl->count() == 0) {
+      // Attempt to refill this local free list.
+      get_from_global_pool(word_sz, fl);
+      // If it didn't work, give up.
+      if (fl->count() == 0) return NULL;
+    }
+    res = fl->get_chunk_at_head();
+    assert(res != NULL, "Why was count non-zero?");
+  }
+  res->markNotFree();
+  assert(!res->is_free(), "shouldn't be marked free");
+  assert(oop(res)->klass_or_null() == NULL, "should look uninitialized");
+  // mangle a just allocated object with a distinct pattern.
+  debug_only(res->mangleAllocated(word_sz));
+  return (HeapWord*)res;
+}
+
+// Get a chunk of blocks of the right size and update related
+// book-keeping stats
+void CFLS_LAB::get_from_global_pool(size_t word_sz, AdaptiveFreeList<FreeChunk>* 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(ResizeOldPLAB || 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 behavior.
+  // 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(CMSOldPLABMin,
+          MIN2(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("[" SIZE_FORMAT "]: " SIZE_FORMAT,
+                               i, (size_t)_blocks_to_claim[i].average());
+      }
+    }
+  }
+}
+
+// If this is changed in the future to allow parallel
+// access, one would need to take the FL locks and,
+// depending on how it is used, stagger access from
+// parallel threads to reduce contention.
+void CFLS_LAB::retire(int tid) {
+  // We run this single threaded with the world stopped;
+  // so no need for locks and such.
+  NOT_PRODUCT(Thread* t = Thread::current();)
+  assert(Thread::current()->is_VM_thread(), "Error");
+  for (size_t i =  CompactibleFreeListSpace::IndexSetStart;
+       i < CompactibleFreeListSpace::IndexSetSize;
+       i += CompactibleFreeListSpace::IndexSetStride) {
+    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");
+      {
+        // MutexLockerEx x(_cfls->_indexedFreeListParLocks[i],
+        //                Mutex::_no_safepoint_check_flag);
+
+        // 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] <= ParallelGCThreads, "Too big");
+        if (num_retire > 0) {
+          _cfls->_indexedFreeList[i].prepend(&_indexedFreeList[i]);
+          // Reset this list.
+          _indexedFreeList[i] = AdaptiveFreeList<FreeChunk>();
+          _indexedFreeList[i].set_size(i);
+        }
+      }
+      if (PrintOldPLAB) {
+        gclog_or_tty->print_cr("%d[" SIZE_FORMAT "]: " SIZE_FORMAT "/" SIZE_FORMAT "/" SIZE_FORMAT,
+                               tid, i, num_retire, _num_blocks[i], (size_t)_blocks_to_claim[i].average());
+      }
+      // Reset stats for next round
+      _num_blocks[i]         = 0;
+    }
+  }
+}
+
+// Used by par_get_chunk_of_blocks() for the chunks from the
+// indexed_free_lists.  Looks for a chunk with size that is a multiple
+// of "word_sz" and if found, splits it into "word_sz" chunks and add
+// to the free list "fl".  "n" is the maximum number of chunks to
+// be added to "fl".
+bool CompactibleFreeListSpace:: par_get_chunk_of_blocks_IFL(size_t word_sz, size_t n, AdaptiveFreeList<FreeChunk>* fl) {
+
+  // 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) {
+      AdaptiveFreeList<FreeChunk> fl_for_cur_sz;  // Empty.
+      fl_for_cur_sz.set_size(cur_sz);
+      {
+        MutexLockerEx x(_indexedFreeListParLocks[cur_sz],
+                        Mutex::_no_safepoint_check_flag);
+        AdaptiveFreeList<FreeChunk>* gfl = &_indexedFreeList[cur_sz];
+        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 = gfl->split_deaths() +
+                             fl_for_cur_sz.count();
+            gfl->set_split_deaths(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.get_chunk_at_head()) != 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();
+            assert(fc->is_free(), "Error");
+            for (int i = k-1; i >= 0; i--) {
+              FreeChunk* ffc = (FreeChunk*)((HeapWord*)fc + i * word_sz);
+              assert((i != 0) ||
+                        ((fc == ffc) && ffc->is_free() &&
+                         (ffc->size() == k*word_sz) && (fc_size == word_sz)),
+                        "Counting error");
+              ffc->set_size(word_sz);
+              ffc->link_prev(NULL); // Mark as a free block for other (parallel) GC threads.
+              ffc->link_next(NULL);
+              // Above must occur before BOT is updated below.
+              OrderAccess::storestore();
+              // splitting from the right, fc_size == i * word_sz
+              _bt.mark_block((HeapWord*)ffc, word_sz, true /* reducing */);
+              fc_size -= word_sz;
+              assert(fc_size == i*word_sz, "Error");
+              _bt.verify_not_unallocated((HeapWord*)ffc, word_sz);
+              _bt.verify_single_block((HeapWord*)fc, fc_size);
+              _bt.verify_single_block((HeapWord*)ffc, word_sz);
+              // Push this on "fl".
+              fl->return_chunk_at_head(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].split_births() + num;
+        _indexedFreeList[word_sz].set_split_births(births);
+        return true;
+      }
+    }
+    return found;
+  }
+}
+
+FreeChunk* CompactibleFreeListSpace::get_n_way_chunk_to_split(size_t word_sz, size_t n) {
+
+  FreeChunk* fc = NULL;
+  FreeChunk* rem_fc = NULL;
+  size_t rem;
+  {
+    MutexLockerEx x(parDictionaryAllocLock(),
+                    Mutex::_no_safepoint_check_flag);
+    while (n > 0) {
+      fc = dictionary()->get_chunk(MAX2(n * word_sz, _dictionary->min_size()),
+                                  FreeBlockDictionary<FreeChunk>::atLeast);
+      if (fc != NULL) {
+        break;
+      } else {
+        n--;
+      }
+    }
+    if (fc == NULL) return NULL;
+    // Otherwise, split up that block.
+    assert((ssize_t)n >= 1, "Control point invariant");
+    assert(fc->is_free(), "Error: should be a free block");
+    _bt.verify_single_block((HeapWord*)fc, fc->size());
+    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 NULL;
+    }
+
+    _bt.allocated((HeapWord*)fc, fc->size(), true /* reducing */);  // update _unallocated_blk
+    dictionary()->dict_census_update(fc->size(),
+                                     true /*split*/,
+                                     false /*birth*/);
+
+    // 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->set_size(rem);
+      rem_fc->link_prev(NULL); // Mark as a free block for other (parallel) GC threads.
+      rem_fc->link_next(NULL);
+      // Above must occur before BOT is updated below.
+      assert((ssize_t)n > 0 && prefix_size > 0 && rem_fc > fc, "Error");
+      OrderAccess::storestore();
+      _bt.split_block((HeapWord*)fc, fc->size(), prefix_size);
+      assert(fc->is_free(), "Error");
+      fc->set_size(prefix_size);
+      if (rem >= IndexSetSize) {
+        returnChunkToDictionary(rem_fc);
+        dictionary()->dict_census_update(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].return_chunk_at_head(rem_fc);
+    smallSplitBirth(rem);
+  }
+  assert(n * word_sz == fc->size(),
+    err_msg("Chunk size " SIZE_FORMAT " is not exactly splittable by "
+    SIZE_FORMAT " sized chunks of size " SIZE_FORMAT,
+    fc->size(), n, word_sz));
+  return fc;
+}
+
+void CompactibleFreeListSpace:: par_get_chunk_of_blocks_dictionary(size_t word_sz, size_t targetted_number_of_chunks, AdaptiveFreeList<FreeChunk>* fl) {
+
+  FreeChunk* fc = get_n_way_chunk_to_split(word_sz, targetted_number_of_chunks);
+
+  if (fc == NULL) {
+    return;
+  }
+
+  size_t n = fc->size() / word_sz;
+
+  assert((ssize_t)n > 0, "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->set_size(word_sz);
+    ffc->link_prev(NULL); // Mark as a free block for other (parallel) GC threads.
+    ffc->link_next(NULL);
+    // Above must occur before BOT is updated below.
+    OrderAccess::storestore();
+    // splitting from the right, fc_size == (n - i + 1) * wordsize
+    _bt.mark_block((HeapWord*)ffc, word_sz, true /* reducing */);
+    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->return_chunk_at_head(ffc);
+  }
+  // First chunk
+  assert(fc->is_free() && fc->size() == n*word_sz, "Error: should still be a free block");
+  // The blocks above should show their new sizes before the first block below
+  fc->set_size(word_sz);
+  fc->link_prev(NULL);    // idempotent wrt free-ness, see assert above
+  fc->link_next(NULL);
+  _bt.verify_not_unallocated((HeapWord*)fc, fc->size());
+  _bt.verify_single_block((HeapWord*)fc, fc->size());
+  fl->return_chunk_at_head(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].split_births() + n;
+    _indexedFreeList[word_sz].set_split_births(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.");
+}
+
+void CompactibleFreeListSpace:: par_get_chunk_of_blocks(size_t word_sz, size_t n, AdaptiveFreeList<FreeChunk>* fl) {
+  assert(fl->count() == 0, "Precondition.");
+  assert(word_sz < CompactibleFreeListSpace::IndexSetSize,
+         "Precondition");
+
+  if (par_get_chunk_of_blocks_IFL(word_sz, n, fl)) {
+    // Got it
+    return;
+  }
+
+  // Otherwise, we'll split a block from the dictionary.
+  par_get_chunk_of_blocks_dictionary(word_sz, n, fl);
+}
+
+// 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?");
+  // Sets the condition for completion of the subtask (how many threads
+  // need to finish in order to be done).
+  pst->set_n_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?");
+  // Sets the condition for completion of the subtask (how many threads
+  // need to finish in order to be done).
+  pst->set_n_threads(n_threads);
+  pst->set_n_tasks((int)n_tasks);
+}