jdk8-mips64-public/hotspot: src/share/vm/gc_implementation/parallelScavenge/psParallelCompact.hpp@0fbdb4381b99 (annotated)

src/share/vm/gc_implementation/parallelScavenge/psParallelCompact.hpp@0fbdb4381b99 (annotated)

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

Mon, 09 Mar 2009 13:28:46 -0700

author: xdono
date: Mon, 09 Mar 2009 13:28:46 -0700
changeset 1014: 0fbdb4381b99
parent 931: b27c885f75f9
child 1376: 8b46c4d82093
child 1424: 148e5441d916
permissions: -rw-r--r--

6814575: Update copyright year
Summary: Update copyright for files that have been modified in 2009, up to 03/09
Reviewed-by: katleman, tbell, ohair

 /*
  * Copyright 2005-2009 Sun Microsystems, Inc.  All Rights Reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
  * CA 95054 USA or visit www.sun.com if you need additional information or
  * have any questions.
  *
  */
 class ParallelScavengeHeap;
 class PSAdaptiveSizePolicy;
 class PSYoungGen;
 class PSOldGen;
 class PSPermGen;
 class ParCompactionManager;
 class ParallelTaskTerminator;
 class PSParallelCompact;
 class GCTaskManager;
 class GCTaskQueue;
 class PreGCValues;
 class MoveAndUpdateClosure;
 class RefProcTaskExecutor;
 // The SplitInfo class holds the information needed to 'split' a source region
 // so that the live data can be copied to two destination *spaces*.  Normally,
 // all the live data in a region is copied to a single destination space (e.g.,
 // everything live in a region in eden is copied entirely into the old gen).
 // However, when the heap is nearly full, all the live data in eden may not fit
 // into the old gen.  Copying only some of the regions from eden to old gen
 // requires finding a region that does not contain a partial object (i.e., no
 // live object crosses the region boundary) somewhere near the last object that
 // does fit into the old gen.  Since it's not always possible to find such a
 // region, splitting is necessary for predictable behavior.
 //
 // A region is always split at the end of the partial object.  This avoids
 // additional tests when calculating the new location of a pointer, which is a
 // very hot code path.  The partial object and everything to its left will be
 // copied to another space (call it dest_space_1).  The live data to the right
 // of the partial object will be copied either within the space itself, or to a
 // different destination space (distinct from dest_space_1).
 //
 // Split points are identified during the summary phase, when region
 // destinations are computed:  data about the split, including the
 // partial_object_size, is recorded in a SplitInfo record and the
 // partial_object_size field in the summary data is set to zero.  The zeroing is
 // possible (and necessary) since the partial object will move to a different
 // destination space than anything to its right, thus the partial object should
 // not affect the locations of any objects to its right.
 //
 // The recorded data is used during the compaction phase, but only rarely:  when
 // the partial object on the split region will be copied across a destination
 // region boundary.  This test is made once each time a region is filled, and is
 // a simple address comparison, so the overhead is negligible (see
 // PSParallelCompact::first_src_addr()).
 //
 // Notes:
 //
 // Only regions with partial objects are split; a region without a partial
 // object does not need any extra bookkeeping.
 //
 // At most one region is split per space, so the amount of data required is
 // constant.
 //
 // A region is split only when the destination space would overflow.  Once that
 // happens, the destination space is abandoned and no other data (even from
 // other source spaces) is targeted to that destination space.  Abandoning the
 // destination space may leave a somewhat large unused area at the end, if a
 // large object caused the overflow.
 //
 // Future work:
 //
 // More bookkeeping would be required to continue to use the destination space.
 // The most general solution would allow data from regions in two different
 // source spaces to be "joined" in a single destination region.  At the very
 // least, additional code would be required in next_src_region() to detect the
 // join and skip to an out-of-order source region.  If the join region was also
 // the last destination region to which a split region was copied (the most
 // likely case), then additional work would be needed to get fill_region() to
 // stop iteration and switch to a new source region at the right point.  Basic
 // idea would be to use a fake value for the top of the source space.  It is
 // doable, if a bit tricky.
 //
 // A simpler (but less general) solution would fill the remainder of the
 // destination region with a dummy object and continue filling the next
 // destination region.
 class SplitInfo
 {
 public:
   // Return true if this split info is valid (i.e., if a split has been
   // recorded).  The very first region cannot have a partial object and thus is
   // never split, so 0 is the 'invalid' value.
   bool is_valid() const { return _src_region_idx > 0; }
   // Return true if this split holds data for the specified source region.
   inline bool is_split(size_t source_region) const;
   // The index of the split region, the size of the partial object on that
   // region and the destination of the partial object.
   size_t    src_region_idx() const   { return _src_region_idx; }
   size_t    partial_obj_size() const { return _partial_obj_size; }
   HeapWord* destination() const      { return _destination; }
   // The destination count of the partial object referenced by this split
   // (either 1 or 2).  This must be added to the destination count of the
   // remainder of the source region.
   unsigned int destination_count() const { return _destination_count; }
   // If a word within the partial object will be written to the first word of a
   // destination region, this is the address of the destination region;
   // otherwise this is NULL.
   HeapWord* dest_region_addr() const     { return _dest_region_addr; }
   // If a word within the partial object will be written to the first word of a
   // destination region, this is the address of that word within the partial
   // object; otherwise this is NULL.
   HeapWord* first_src_addr() const       { return _first_src_addr; }
   // Record the data necessary to split the region src_region_idx.
   void record(size_t src_region_idx, size_t partial_obj_size,
               HeapWord* destination);
   void clear();
   DEBUG_ONLY(void verify_clear();)
 private:
   size_t       _src_region_idx;
   size_t       _partial_obj_size;
   HeapWord*    _destination;
   unsigned int _destination_count;
   HeapWord*    _dest_region_addr;
   HeapWord*    _first_src_addr;
 };
 inline bool SplitInfo::is_split(size_t region_idx) const
 {
   return _src_region_idx == region_idx && is_valid();
 }
 class SpaceInfo
 {
  public:
   MutableSpace* space() const { return _space; }
   // Where the free space will start after the collection.  Valid only after the
   // summary phase completes.
   HeapWord* new_top() const { return _new_top; }
   // Allows new_top to be set.
   HeapWord** new_top_addr() { return &_new_top; }
   // Where the smallest allowable dense prefix ends (used only for perm gen).
   HeapWord* min_dense_prefix() const { return _min_dense_prefix; }
   // Where the dense prefix ends, or the compacted region begins.
   HeapWord* dense_prefix() const { return _dense_prefix; }
   // The start array for the (generation containing the) space, or NULL if there
   // is no start array.
   ObjectStartArray* start_array() const { return _start_array; }
   SplitInfo& split_info() { return _split_info; }
   void set_space(MutableSpace* s)           { _space = s; }
   void set_new_top(HeapWord* addr)          { _new_top = addr; }
   void set_min_dense_prefix(HeapWord* addr) { _min_dense_prefix = addr; }
   void set_dense_prefix(HeapWord* addr)     { _dense_prefix = addr; }
   void set_start_array(ObjectStartArray* s) { _start_array = s; }
   void publish_new_top() const              { _space->set_top(_new_top); }
  private:
   MutableSpace*     _space;
   HeapWord*         _new_top;
   HeapWord*         _min_dense_prefix;
   HeapWord*         _dense_prefix;
   ObjectStartArray* _start_array;
   SplitInfo         _split_info;
 };
 class ParallelCompactData
 {
 public:
   // Sizes are in HeapWords, unless indicated otherwise.
   static const size_t Log2RegionSize;
   static const size_t RegionSize;
   static const size_t RegionSizeBytes;
   // Mask for the bits in a size_t to get an offset within a region.
   static const size_t RegionSizeOffsetMask;
   // Mask for the bits in a pointer to get an offset within a region.
   static const size_t RegionAddrOffsetMask;
   // Mask for the bits in a pointer to get the address of the start of a region.
   static const size_t RegionAddrMask;
   class RegionData
   {
   public:
     // Destination address of the region.
     HeapWord* destination() const { return _destination; }
     // The first region containing data destined for this region.
     size_t source_region() const { return _source_region; }
     // The object (if any) starting in this region and ending in a different
     // region that could not be updated during the main (parallel) compaction
     // phase.  This is different from _partial_obj_addr, which is an object that
     // extends onto a source region.  However, the two uses do not overlap in
     // time, so the same field is used to save space.
     HeapWord* deferred_obj_addr() const { return _partial_obj_addr; }
     // The starting address of the partial object extending onto the region.
     HeapWord* partial_obj_addr() const { return _partial_obj_addr; }
     // Size of the partial object extending onto the region (words).
     size_t partial_obj_size() const { return _partial_obj_size; }
     // Size of live data that lies within this region due to objects that start
     // in this region (words).  This does not include the partial object
     // extending onto the region (if any), or the part of an object that extends
     // onto the next region (if any).
     size_t live_obj_size() const { return _dc_and_los & los_mask; }
     // Total live data that lies within the region (words).
     size_t data_size() const { return partial_obj_size() + live_obj_size(); }
     // The destination_count is the number of other regions to which data from
     // this region will be copied.  At the end of the summary phase, the valid
     // values of destination_count are
     //
     // 0 - data from the region will be compacted completely into itself, or the
     //     region is empty.  The region can be claimed and then filled.
     // 1 - data from the region will be compacted into 1 other region; some
     //     data from the region may also be compacted into the region itself.
     // 2 - data from the region will be copied to 2 other regions.
     //
     // During compaction as regions are emptied, the destination_count is
     // decremented (atomically) and when it reaches 0, it can be claimed and
     // then filled.
     //
     // A region is claimed for processing by atomically changing the
     // destination_count to the claimed value (dc_claimed).  After a region has
     // been filled, the destination_count should be set to the completed value
     // (dc_completed).
     inline uint destination_count() const;
     inline uint destination_count_raw() const;
     // The location of the java heap data that corresponds to this region.
     inline HeapWord* data_location() const;
     // The highest address referenced by objects in this region.
     inline HeapWord* highest_ref() const;
     // Whether this region is available to be claimed, has been claimed, or has
     // been completed.
     //
     // Minor subtlety:  claimed() returns true if the region is marked
     // completed(), which is desirable since a region must be claimed before it
     // can be completed.
     bool available() const { return _dc_and_los < dc_one; }
     bool claimed() const   { return _dc_and_los >= dc_claimed; }
     bool completed() const { return _dc_and_los >= dc_completed; }
     // These are not atomic.
     void set_destination(HeapWord* addr)       { _destination = addr; }
     void set_source_region(size_t region)      { _source_region = region; }
     void set_deferred_obj_addr(HeapWord* addr) { _partial_obj_addr = addr; }
     void set_partial_obj_addr(HeapWord* addr)  { _partial_obj_addr = addr; }
     void set_partial_obj_size(size_t words)    {
       _partial_obj_size = (region_sz_t) words;
     }
     inline void set_destination_count(uint count);
     inline void set_live_obj_size(size_t words);
     inline void set_data_location(HeapWord* addr);
     inline void set_completed();
     inline bool claim_unsafe();
     // These are atomic.
     inline void add_live_obj(size_t words);
     inline void set_highest_ref(HeapWord* addr);
     inline void decrement_destination_count();
     inline bool claim();
   private:
     // The type used to represent object sizes within a region.
     typedef uint region_sz_t;
     // Constants for manipulating the _dc_and_los field, which holds both the
     // destination count and live obj size.  The live obj size lives at the
     // least significant end so no masking is necessary when adding.
     static const region_sz_t dc_shift;           // Shift amount.
     static const region_sz_t dc_mask;            // Mask for destination count.
     static const region_sz_t dc_one;             // 1, shifted appropriately.
     static const region_sz_t dc_claimed;         // Region has been claimed.
     static const region_sz_t dc_completed;       // Region has been completed.
     static const region_sz_t los_mask;           // Mask for live obj size.
     HeapWord*            _destination;
     size_t               _source_region;
     HeapWord*            _partial_obj_addr;
     region_sz_t          _partial_obj_size;
     region_sz_t volatile _dc_and_los;
 #ifdef ASSERT
     // These enable optimizations that are only partially implemented.  Use
     // debug builds to prevent the code fragments from breaking.
     HeapWord*            _data_location;
     HeapWord*            _highest_ref;
 #endif  // #ifdef ASSERT
 #ifdef ASSERT
    public:
     uint            _pushed;   // 0 until region is pushed onto a worker's stack
    private:
 #endif
   };
 public:
   ParallelCompactData();
   bool initialize(MemRegion covered_region);
   size_t region_count() const { return _region_count; }
   // Convert region indices to/from RegionData pointers.
   inline RegionData* region(size_t region_idx) const;
   inline size_t     region(const RegionData* const region_ptr) const;
   // Returns true if the given address is contained within the region
   bool region_contains(size_t region_index, HeapWord* addr);
   void add_obj(HeapWord* addr, size_t len);
   void add_obj(oop p, size_t len) { add_obj((HeapWord*)p, len); }
   // Fill in the regions covering [beg, end) so that no data moves; i.e., the
   // destination of region n is simply the start of region n.  The argument beg
   // must be region-aligned; end need not be.
   void summarize_dense_prefix(HeapWord* beg, HeapWord* end);
   HeapWord* summarize_split_space(size_t src_region, SplitInfo& split_info,
                                   HeapWord* destination, HeapWord* target_end,
                                   HeapWord** target_next);
   bool summarize(SplitInfo& split_info,
                  HeapWord* source_beg, HeapWord* source_end,
                  HeapWord** source_next,
                  HeapWord* target_beg, HeapWord* target_end,
                  HeapWord** target_next);
   void clear();
   void clear_range(size_t beg_region, size_t end_region);
   void clear_range(HeapWord* beg, HeapWord* end) {
     clear_range(addr_to_region_idx(beg), addr_to_region_idx(end));
   }
   // Return the number of words between addr and the start of the region
   // containing addr.
   inline size_t     region_offset(const HeapWord* addr) const;
   // Convert addresses to/from a region index or region pointer.
   inline size_t     addr_to_region_idx(const HeapWord* addr) const;
   inline RegionData* addr_to_region_ptr(const HeapWord* addr) const;
   inline HeapWord*  region_to_addr(size_t region) const;
   inline HeapWord*  region_to_addr(size_t region, size_t offset) const;
   inline HeapWord*  region_to_addr(const RegionData* region) const;
   inline HeapWord*  region_align_down(HeapWord* addr) const;
   inline HeapWord*  region_align_up(HeapWord* addr) const;
   inline bool       is_region_aligned(HeapWord* addr) const;
   // Return the address one past the end of the partial object.
   HeapWord* partial_obj_end(size_t region_idx) const;
   // Return the new location of the object p after the
   // the compaction.
   HeapWord* calc_new_pointer(HeapWord* addr);
   HeapWord* calc_new_pointer(oop p) {
     return calc_new_pointer((HeapWord*) p);
   }
   // Return the updated address for the given klass
   klassOop calc_new_klass(klassOop);
 #ifdef  ASSERT
   void verify_clear(const PSVirtualSpace* vspace);
   void verify_clear();
 #endif  // #ifdef ASSERT
 private:
   bool initialize_region_data(size_t region_size);
   PSVirtualSpace* create_vspace(size_t count, size_t element_size);
 private:
   HeapWord*       _region_start;
 #ifdef  ASSERT
   HeapWord*       _region_end;
 #endif  // #ifdef ASSERT
   PSVirtualSpace* _region_vspace;
   RegionData*     _region_data;
   size_t          _region_count;
 };
 inline uint
 ParallelCompactData::RegionData::destination_count_raw() const
 {
   return _dc_and_los & dc_mask;
 }
 inline uint
 ParallelCompactData::RegionData::destination_count() const
 {
   return destination_count_raw() >> dc_shift;
 }
 inline void
 ParallelCompactData::RegionData::set_destination_count(uint count)
 {
   assert(count <= (dc_completed >> dc_shift), "count too large");
   const region_sz_t live_sz = (region_sz_t) live_obj_size();
   _dc_and_los = (count << dc_shift) | live_sz;
 }
 inline void ParallelCompactData::RegionData::set_live_obj_size(size_t words)
 {
   assert(words <= los_mask, "would overflow");
   _dc_and_los = destination_count_raw() | (region_sz_t)words;
 }
 inline void ParallelCompactData::RegionData::decrement_destination_count()
 {
   assert(_dc_and_los < dc_claimed, "already claimed");
   assert(_dc_and_los >= dc_one, "count would go negative");
   Atomic::add((int)dc_mask, (volatile int*)&_dc_and_los);
 }
 inline HeapWord* ParallelCompactData::RegionData::data_location() const
 {
   DEBUG_ONLY(return _data_location;)
   NOT_DEBUG(return NULL;)
 }
 inline HeapWord* ParallelCompactData::RegionData::highest_ref() const
 {
   DEBUG_ONLY(return _highest_ref;)
   NOT_DEBUG(return NULL;)
 }
 inline void ParallelCompactData::RegionData::set_data_location(HeapWord* addr)
 {
   DEBUG_ONLY(_data_location = addr;)
 }
 inline void ParallelCompactData::RegionData::set_completed()
 {
   assert(claimed(), "must be claimed first");
   _dc_and_los = dc_completed | (region_sz_t) live_obj_size();
 }
 // MT-unsafe claiming of a region.  Should only be used during single threaded
 // execution.
 inline bool ParallelCompactData::RegionData::claim_unsafe()
 {
   if (available()) {
     _dc_and_los |= dc_claimed;
     return true;
   }
   return false;
 }
 inline void ParallelCompactData::RegionData::add_live_obj(size_t words)
 {
   assert(words <= (size_t)los_mask - live_obj_size(), "overflow");
   Atomic::add((int) words, (volatile int*) &_dc_and_los);
 }
 inline void ParallelCompactData::RegionData::set_highest_ref(HeapWord* addr)
 {
 #ifdef ASSERT
   HeapWord* tmp = _highest_ref;
   while (addr > tmp) {
     tmp = (HeapWord*)Atomic::cmpxchg_ptr(addr, &_highest_ref, tmp);
   }
 #endif  // #ifdef ASSERT
 }
 inline bool ParallelCompactData::RegionData::claim()
 {
   const int los = (int) live_obj_size();
   const int old = Atomic::cmpxchg(dc_claimed | los,
                                   (volatile int*) &_dc_and_los, los);
   return old == los;
 }
 inline ParallelCompactData::RegionData*
 ParallelCompactData::region(size_t region_idx) const
 {
   assert(region_idx <= region_count(), "bad arg");
   return _region_data + region_idx;
 }
 inline size_t
 ParallelCompactData::region(const RegionData* const region_ptr) const
 {
   assert(region_ptr >= _region_data, "bad arg");
   assert(region_ptr <= _region_data + region_count(), "bad arg");
   return pointer_delta(region_ptr, _region_data, sizeof(RegionData));
 }
 inline size_t
 ParallelCompactData::region_offset(const HeapWord* addr) const
 {
   assert(addr >= _region_start, "bad addr");
   assert(addr <= _region_end, "bad addr");
   return (size_t(addr) & RegionAddrOffsetMask) >> LogHeapWordSize;
 }
 inline size_t
 ParallelCompactData::addr_to_region_idx(const HeapWord* addr) const
 {
   assert(addr >= _region_start, "bad addr");
   assert(addr <= _region_end, "bad addr");
   return pointer_delta(addr, _region_start) >> Log2RegionSize;
 }
 inline ParallelCompactData::RegionData*
 ParallelCompactData::addr_to_region_ptr(const HeapWord* addr) const
 {
   return region(addr_to_region_idx(addr));
 }
 inline HeapWord*
 ParallelCompactData::region_to_addr(size_t region) const
 {
   assert(region <= _region_count, "region out of range");
   return _region_start + (region << Log2RegionSize);
 }
 inline HeapWord*
 ParallelCompactData::region_to_addr(const RegionData* region) const
 {
   return region_to_addr(pointer_delta(region, _region_data,
                                       sizeof(RegionData)));
 }
 inline HeapWord*
 ParallelCompactData::region_to_addr(size_t region, size_t offset) const
 {
   assert(region <= _region_count, "region out of range");
   assert(offset < RegionSize, "offset too big");  // This may be too strict.
   return region_to_addr(region) + offset;
 }
 inline HeapWord*
 ParallelCompactData::region_align_down(HeapWord* addr) const
 {
   assert(addr >= _region_start, "bad addr");
   assert(addr < _region_end + RegionSize, "bad addr");
   return (HeapWord*)(size_t(addr) & RegionAddrMask);
 }
 inline HeapWord*
 ParallelCompactData::region_align_up(HeapWord* addr) const
 {
   assert(addr >= _region_start, "bad addr");
   assert(addr <= _region_end, "bad addr");
   return region_align_down(addr + RegionSizeOffsetMask);
 }
 inline bool
 ParallelCompactData::is_region_aligned(HeapWord* addr) const
 {
   return region_offset(addr) == 0;
 }
 // Abstract closure for use with ParMarkBitMap::iterate(), which will invoke the
 // do_addr() method.
 //
 // The closure is initialized with the number of heap words to process
 // (words_remaining()), and becomes 'full' when it reaches 0.  The do_addr()
 // methods in subclasses should update the total as words are processed.  Since
 // only one subclass actually uses this mechanism to terminate iteration, the
 // default initial value is > 0.  The implementation is here and not in the
 // single subclass that uses it to avoid making is_full() virtual, and thus
 // adding a virtual call per live object.
 class ParMarkBitMapClosure: public StackObj {
  public:
   typedef ParMarkBitMap::idx_t idx_t;
   typedef ParMarkBitMap::IterationStatus IterationStatus;
  public:
   inline ParMarkBitMapClosure(ParMarkBitMap* mbm, ParCompactionManager* cm,
                               size_t words = max_uintx);
   inline ParCompactionManager* compaction_manager() const;
   inline ParMarkBitMap*        bitmap() const;
   inline size_t                words_remaining() const;
   inline bool                  is_full() const;
   inline HeapWord*             source() const;
   inline void                  set_source(HeapWord* addr);
   virtual IterationStatus do_addr(HeapWord* addr, size_t words) = 0;
  protected:
   inline void decrement_words_remaining(size_t words);
  private:
   ParMarkBitMap* const        _bitmap;
   ParCompactionManager* const _compaction_manager;
   DEBUG_ONLY(const size_t     _initial_words_remaining;) // Useful in debugger.
   size_t                      _words_remaining; // Words left to copy.
  protected:
   HeapWord*                   _source;          // Next addr that would be read.
 };
 inline
 ParMarkBitMapClosure::ParMarkBitMapClosure(ParMarkBitMap* bitmap,
                                            ParCompactionManager* cm,
                                            size_t words):
   _bitmap(bitmap), _compaction_manager(cm)
 #ifdef  ASSERT
   , _initial_words_remaining(words)
 #endif
 {
   _words_remaining = words;
   _source = NULL;
 }
 inline ParCompactionManager* ParMarkBitMapClosure::compaction_manager() const {
   return _compaction_manager;
 }
 inline ParMarkBitMap* ParMarkBitMapClosure::bitmap() const {
   return _bitmap;
 }
 inline size_t ParMarkBitMapClosure::words_remaining() const {
   return _words_remaining;
 }
 inline bool ParMarkBitMapClosure::is_full() const {
   return words_remaining() == 0;
 }
 inline HeapWord* ParMarkBitMapClosure::source() const {
   return _source;
 }
 inline void ParMarkBitMapClosure::set_source(HeapWord* addr) {
   _source = addr;
 }
 inline void ParMarkBitMapClosure::decrement_words_remaining(size_t words) {
   assert(_words_remaining >= words, "processed too many words");
   _words_remaining -= words;
 }
 // The UseParallelOldGC collector is a stop-the-world garbage collector that
 // does parts of the collection using parallel threads.  The collection includes
 // the tenured generation and the young generation.  The permanent generation is
 // collected at the same time as the other two generations but the permanent
 // generation is collect by a single GC thread.  The permanent generation is
 // collected serially because of the requirement that during the processing of a
 // klass AAA, any objects reference by AAA must already have been processed.
 // This requirement is enforced by a left (lower address) to right (higher
 // address) sliding compaction.
 //
 // There are four phases of the collection.
 //
 //      - marking phase
 //      - summary phase
 //      - compacting phase
 //      - clean up phase
 //
 // Roughly speaking these phases correspond, respectively, to
 //      - mark all the live objects
 //      - calculate the destination of each object at the end of the collection
 //      - move the objects to their destination
 //      - update some references and reinitialize some variables
 //
 // These three phases are invoked in PSParallelCompact::invoke_no_policy().  The
 // marking phase is implemented in PSParallelCompact::marking_phase() and does a
 // complete marking of the heap.  The summary phase is implemented in
 // PSParallelCompact::summary_phase().  The move and update phase is implemented
 // in PSParallelCompact::compact().
 //
 // A space that is being collected is divided into regions and with each region
 // is associated an object of type ParallelCompactData.  Each region is of a
 // fixed size and typically will contain more than 1 object and may have parts
 // of objects at the front and back of the region.
 //
 // region            -----+---------------------+----------
 // objects covered   [ AAA  )[ BBB )[ CCC   )[ DDD     )
 //
 // The marking phase does a complete marking of all live objects in the heap.
 // The marking also compiles the size of the data for all live objects covered
 // by the region.  This size includes the part of any live object spanning onto
 // the region (part of AAA if it is live) from the front, all live objects
 // contained in the region (BBB and/or CCC if they are live), and the part of
 // any live objects covered by the region that extends off the region (part of
 // DDD if it is live).  The marking phase uses multiple GC threads and marking
 // is done in a bit array of type ParMarkBitMap.  The marking of the bit map is
 // done atomically as is the accumulation of the size of the live objects
 // covered by a region.
 //
 // The summary phase calculates the total live data to the left of each region
 // XXX.  Based on that total and the bottom of the space, it can calculate the
 // starting location of the live data in XXX.  The summary phase calculates for
 // each region XXX quantites such as
 //
 //      - the amount of live data at the beginning of a region from an object
 //        entering the region.
 //      - the location of the first live data on the region
 //      - a count of the number of regions receiving live data from XXX.
 //
 // See ParallelCompactData for precise details.  The summary phase also
 // calculates the dense prefix for the compaction.  The dense prefix is a
 // portion at the beginning of the space that is not moved.  The objects in the
 // dense prefix do need to have their object references updated.  See method
 // summarize_dense_prefix().
 //
 // The summary phase is done using 1 GC thread.
 //
 // The compaction phase moves objects to their new location and updates all
 // references in the object.
 //
 // A current exception is that objects that cross a region boundary are moved
 // but do not have their references updated.  References are not updated because
 // it cannot easily be determined if the klass pointer KKK for the object AAA
 // has been updated.  KKK likely resides in a region to the left of the region
 // containing AAA.  These AAA's have there references updated at the end in a
 // clean up phase.  See the method PSParallelCompact::update_deferred_objects().
 // An alternate strategy is being investigated for this deferral of updating.
 //
 // Compaction is done on a region basis.  A region that is ready to be filled is
 // put on a ready list and GC threads take region off the list and fill them.  A
 // region is ready to be filled if it empty of live objects.  Such a region may
 // have been initially empty (only contained dead objects) or may have had all
 // its live objects copied out already.  A region that compacts into itself is
 // also ready for filling.  The ready list is initially filled with empty
 // regions and regions compacting into themselves.  There is always at least 1
 // region that can be put on the ready list.  The regions are atomically added
 // and removed from the ready list.
 class PSParallelCompact : AllStatic {
  public:
   // Convenient access to type names.
   typedef ParMarkBitMap::idx_t idx_t;
   typedef ParallelCompactData::RegionData RegionData;
   typedef enum {
     perm_space_id, old_space_id, eden_space_id,
     from_space_id, to_space_id, last_space_id
   } SpaceId;
  public:
   // Inline closure decls
   //
   class IsAliveClosure: public BoolObjectClosure {
    public:
     virtual void do_object(oop p);
     virtual bool do_object_b(oop p);
   };
   class KeepAliveClosure: public OopClosure {
    private:
     ParCompactionManager* _compaction_manager;
    protected:
     template <class T> inline void do_oop_work(T* p);
    public:
     KeepAliveClosure(ParCompactionManager* cm) : _compaction_manager(cm) { }
     virtual void do_oop(oop* p);
     virtual void do_oop(narrowOop* p);
   };
   // Current unused
   class FollowRootClosure: public OopsInGenClosure {
    private:
     ParCompactionManager* _compaction_manager;
    public:
     FollowRootClosure(ParCompactionManager* cm) : _compaction_manager(cm) { }
     virtual void do_oop(oop* p);
     virtual void do_oop(narrowOop* p);
     virtual const bool do_nmethods() const { return true; }
   };
   class FollowStackClosure: public VoidClosure {
    private:
     ParCompactionManager* _compaction_manager;
    public:
     FollowStackClosure(ParCompactionManager* cm) : _compaction_manager(cm) { }
     virtual void do_void();
   };
   class AdjustPointerClosure: public OopsInGenClosure {
    private:
     bool _is_root;
    public:
     AdjustPointerClosure(bool is_root) : _is_root(is_root) { }
     virtual void do_oop(oop* p);
     virtual void do_oop(narrowOop* p);
   };
   // Closure for verifying update of pointers.  Does not
   // have any side effects.
   class VerifyUpdateClosure: public ParMarkBitMapClosure {
     const MutableSpace* _space; // Is this ever used?
    public:
     VerifyUpdateClosure(ParCompactionManager* cm, const MutableSpace* sp) :
       ParMarkBitMapClosure(PSParallelCompact::mark_bitmap(), cm), _space(sp)
     { }
     virtual IterationStatus do_addr(HeapWord* addr, size_t words);
     const MutableSpace* space() { return _space; }
   };
   // Closure for updating objects altered for debug checking
   class ResetObjectsClosure: public ParMarkBitMapClosure {
    public:
     ResetObjectsClosure(ParCompactionManager* cm):
       ParMarkBitMapClosure(PSParallelCompact::mark_bitmap(), cm)
     { }
     virtual IterationStatus do_addr(HeapWord* addr, size_t words);
   };
   friend class KeepAliveClosure;
   friend class FollowStackClosure;
   friend class AdjustPointerClosure;
   friend class FollowRootClosure;
   friend class instanceKlassKlass;
   friend class RefProcTaskProxy;
  private:
   static elapsedTimer         _accumulated_time;
   static unsigned int         _total_invocations;
   static unsigned int         _maximum_compaction_gc_num;
   static jlong                _time_of_last_gc;   // ms
   static CollectorCounters*   _counters;
   static ParMarkBitMap        _mark_bitmap;
   static ParallelCompactData  _summary_data;
   static IsAliveClosure       _is_alive_closure;
   static SpaceInfo            _space_info[last_space_id];
   static bool                 _print_phases;
   static AdjustPointerClosure _adjust_root_pointer_closure;
   static AdjustPointerClosure _adjust_pointer_closure;
   // Reference processing (used in ...follow_contents)
   static ReferenceProcessor*  _ref_processor;
   // Updated location of intArrayKlassObj.
   static klassOop _updated_int_array_klass_obj;
   // Values computed at initialization and used by dead_wood_limiter().
   static double _dwl_mean;
   static double _dwl_std_dev;
   static double _dwl_first_term;
   static double _dwl_adjustment;
 #ifdef  ASSERT
   static bool   _dwl_initialized;
 #endif  // #ifdef ASSERT
  private:
   // Closure accessors
   static OopClosure* adjust_pointer_closure()      { return (OopClosure*)&_adjust_pointer_closure; }
   static OopClosure* adjust_root_pointer_closure() { return (OopClosure*)&_adjust_root_pointer_closure; }
   static BoolObjectClosure* is_alive_closure()     { return (BoolObjectClosure*)&_is_alive_closure; }
   static void initialize_space_info();
   // Return true if details about individual phases should be printed.
   static inline bool print_phases();
   // Clear the marking bitmap and summary data that cover the specified space.
   static void clear_data_covering_space(SpaceId id);
   static void pre_compact(PreGCValues* pre_gc_values);
   static void post_compact();
   // Mark live objects
   static void marking_phase(ParCompactionManager* cm,
                             bool maximum_heap_compaction);
   static void follow_stack(ParCompactionManager* cm);
   static void follow_weak_klass_links(ParCompactionManager* cm);
   template <class T> static inline void adjust_pointer(T* p, bool is_root);
   static void adjust_root_pointer(oop* p) { adjust_pointer(p, true); }
   template <class T>
   static inline void follow_root(ParCompactionManager* cm, T* p);
   // Compute the dense prefix for the designated space.  This is an experimental
   // implementation currently not used in production.
   static HeapWord* compute_dense_prefix_via_density(const SpaceId id,
                                                     bool maximum_compaction);
   // Methods used to compute the dense prefix.
   // Compute the value of the normal distribution at x = density.  The mean and
   // standard deviation are values saved by initialize_dead_wood_limiter().
   static inline double normal_distribution(double density);
   // Initialize the static vars used by dead_wood_limiter().
   static void initialize_dead_wood_limiter();
   // Return the percentage of space that can be treated as "dead wood" (i.e.,
   // not reclaimed).
   static double dead_wood_limiter(double density, size_t min_percent);
   // Find the first (left-most) region in the range [beg, end) that has at least
   // dead_words of dead space to the left.  The argument beg must be the first
   // region in the space that is not completely live.
   static RegionData* dead_wood_limit_region(const RegionData* beg,
                                             const RegionData* end,
                                             size_t dead_words);
   // Return a pointer to the first region in the range [beg, end) that is not
   // completely full.
   static RegionData* first_dead_space_region(const RegionData* beg,
                                              const RegionData* end);
   // Return a value indicating the benefit or 'yield' if the compacted region
   // were to start (or equivalently if the dense prefix were to end) at the
   // candidate region.  Higher values are better.
   //
   // The value is based on the amount of space reclaimed vs. the costs of (a)
   // updating references in the dense prefix plus (b) copying objects and
   // updating references in the compacted region.
   static inline double reclaimed_ratio(const RegionData* const candidate,
                                        HeapWord* const bottom,
                                        HeapWord* const top,
                                        HeapWord* const new_top);
   // Compute the dense prefix for the designated space.
   static HeapWord* compute_dense_prefix(const SpaceId id,
                                         bool maximum_compaction);
   // Return true if dead space crosses onto the specified Region; bit must be
   // the bit index corresponding to the first word of the Region.
   static inline bool dead_space_crosses_boundary(const RegionData* region,
                                                  idx_t bit);
   // Summary phase utility routine to fill dead space (if any) at the dense
   // prefix boundary.  Should only be called if the the dense prefix is
   // non-empty.
   static void fill_dense_prefix_end(SpaceId id);
   // Clear the summary data source_region field for the specified addresses.
   static void clear_source_region(HeapWord* beg_addr, HeapWord* end_addr);
 #ifndef PRODUCT
   // Routines to provoke splitting a young gen space (ParallelOldGCSplitALot).
   // Fill the region [start, start + words) with live object(s).  Only usable
   // for the old and permanent generations.
   static void fill_with_live_objects(SpaceId id, HeapWord* const start,
                                      size_t words);
   // Include the new objects in the summary data.
   static void summarize_new_objects(SpaceId id, HeapWord* start);
   // Add live objects to a survivor space since it's rare that both survivors
   // are non-empty.
   static void provoke_split_fill_survivor(SpaceId id);
   // Add live objects and/or choose the dense prefix to provoke splitting.
   static void provoke_split(bool & maximum_compaction);
 #endif
   static void summarize_spaces_quick();
   static void summarize_space(SpaceId id, bool maximum_compaction);
   static void summary_phase(ParCompactionManager* cm, bool maximum_compaction);
   // Adjust addresses in roots.  Does not adjust addresses in heap.
   static void adjust_roots();
   // Serial code executed in preparation for the compaction phase.
   static void compact_prologue();
   // Move objects to new locations.
   static void compact_perm(ParCompactionManager* cm);
   static void compact();
   // Add available regions to the stack and draining tasks to the task queue.
   static void enqueue_region_draining_tasks(GCTaskQueue* q,
                                             uint parallel_gc_threads);
   // Add dense prefix update tasks to the task queue.
   static void enqueue_dense_prefix_tasks(GCTaskQueue* q,
                                          uint parallel_gc_threads);
   // Add region stealing tasks to the task queue.
   static void enqueue_region_stealing_tasks(
                                        GCTaskQueue* q,
                                        ParallelTaskTerminator* terminator_ptr,
                                        uint parallel_gc_threads);
   // For debugging only - compacts the old gen serially
   static void compact_serial(ParCompactionManager* cm);
   // If objects are left in eden after a collection, try to move the boundary
   // and absorb them into the old gen.  Returns true if eden was emptied.
   static bool absorb_live_data_from_eden(PSAdaptiveSizePolicy* size_policy,
                                          PSYoungGen* young_gen,
                                          PSOldGen* old_gen);
   // Reset time since last full gc
   static void reset_millis_since_last_gc();
  protected:
 #ifdef VALIDATE_MARK_SWEEP
   static GrowableArray<void*>*           _root_refs_stack;
   static GrowableArray<oop> *            _live_oops;
   static GrowableArray<oop> *            _live_oops_moved_to;
   static GrowableArray<size_t>*          _live_oops_size;
   static size_t                          _live_oops_index;
   static size_t                          _live_oops_index_at_perm;
   static GrowableArray<void*>*           _other_refs_stack;
   static GrowableArray<void*>*           _adjusted_pointers;
   static bool                            _pointer_tracking;
   static bool                            _root_tracking;
   // The following arrays are saved since the time of the last GC and
   // assist in tracking down problems where someone has done an errant
   // store into the heap, usually to an oop that wasn't properly
   // handleized across a GC. If we crash or otherwise fail before the
   // next GC, we can query these arrays to find out the object we had
   // intended to do the store to (assuming it is still alive) and the
   // offset within that object. Covered under RecordMarkSweepCompaction.
   static GrowableArray<HeapWord*> *      _cur_gc_live_oops;
   static GrowableArray<HeapWord*> *      _cur_gc_live_oops_moved_to;
   static GrowableArray<size_t>*          _cur_gc_live_oops_size;
   static GrowableArray<HeapWord*> *      _last_gc_live_oops;
   static GrowableArray<HeapWord*> *      _last_gc_live_oops_moved_to;
   static GrowableArray<size_t>*          _last_gc_live_oops_size;
 #endif
  public:
   class MarkAndPushClosure: public OopClosure {
    private:
     ParCompactionManager* _compaction_manager;
    public:
     MarkAndPushClosure(ParCompactionManager* cm) : _compaction_manager(cm) { }
     virtual void do_oop(oop* p);
     virtual void do_oop(narrowOop* p);
     virtual const bool do_nmethods() const { return true; }
   };
   PSParallelCompact();
   // Convenient accessor for Universe::heap().
   static ParallelScavengeHeap* gc_heap() {
     return (ParallelScavengeHeap*)Universe::heap();
   }
   static void invoke(bool maximum_heap_compaction);
   static void invoke_no_policy(bool maximum_heap_compaction);
   static void post_initialize();
   // Perform initialization for PSParallelCompact that requires
   // allocations.  This should be called during the VM initialization
   // at a pointer where it would be appropriate to return a JNI_ENOMEM
   // in the event of a failure.
   static bool initialize();
   // Public accessors
   static elapsedTimer* accumulated_time() { return &_accumulated_time; }
   static unsigned int total_invocations() { return _total_invocations; }
   static CollectorCounters* counters()    { return _counters; }
   // Used to add tasks
   static GCTaskManager* const gc_task_manager();
   static klassOop updated_int_array_klass_obj() {
     return _updated_int_array_klass_obj;
   }
   // Marking support
   static inline bool mark_obj(oop obj);
   // Check mark and maybe push on marking stack
   template <class T> static inline void mark_and_push(ParCompactionManager* cm,
                                                       T* p);
   // Compaction support.
   // Return true if p is in the range [beg_addr, end_addr).
   static inline bool is_in(HeapWord* p, HeapWord* beg_addr, HeapWord* end_addr);
   static inline bool is_in(oop* p, HeapWord* beg_addr, HeapWord* end_addr);
   // Convenience wrappers for per-space data kept in _space_info.
   static inline MutableSpace*     space(SpaceId space_id);
   static inline HeapWord*         new_top(SpaceId space_id);
   static inline HeapWord*         dense_prefix(SpaceId space_id);
   static inline ObjectStartArray* start_array(SpaceId space_id);
   // Return true if the klass should be updated.
   static inline bool should_update_klass(klassOop k);
   // Move and update the live objects in the specified space.
   static void move_and_update(ParCompactionManager* cm, SpaceId space_id);
   // Process the end of the given region range in the dense prefix.
   // This includes saving any object not updated.
   static void dense_prefix_regions_epilogue(ParCompactionManager* cm,
                                             size_t region_start_index,
                                             size_t region_end_index,
                                             idx_t exiting_object_offset,
                                             idx_t region_offset_start,
                                             idx_t region_offset_end);
   // Update a region in the dense prefix.  For each live object
   // in the region, update it's interior references.  For each
   // dead object, fill it with deadwood. Dead space at the end
   // of a region range will be filled to the start of the next
   // live object regardless of the region_index_end.  None of the
   // objects in the dense prefix move and dead space is dead
   // (holds only dead objects that don't need any processing), so
   // dead space can be filled in any order.
   static void update_and_deadwood_in_dense_prefix(ParCompactionManager* cm,
                                                   SpaceId space_id,
                                                   size_t region_index_start,
                                                   size_t region_index_end);
   // Return the address of the count + 1st live word in the range [beg, end).
   static HeapWord* skip_live_words(HeapWord* beg, HeapWord* end, size_t count);
   // Return the address of the word to be copied to dest_addr, which must be
   // aligned to a region boundary.
   static HeapWord* first_src_addr(HeapWord* const dest_addr,
                                   SpaceId src_space_id,
                                   size_t src_region_idx);
   // Determine the next source region, set closure.source() to the start of the
   // new region return the region index.  Parameter end_addr is the address one
   // beyond the end of source range just processed.  If necessary, switch to a
   // new source space and set src_space_id (in-out parameter) and src_space_top
   // (out parameter) accordingly.
   static size_t next_src_region(MoveAndUpdateClosure& closure,
                                 SpaceId& src_space_id,
                                 HeapWord*& src_space_top,
                                 HeapWord* end_addr);
   // Decrement the destination count for each non-empty source region in the
   // range [beg_region, region(region_align_up(end_addr))).  If the destination
   // count for a region goes to 0 and it needs to be filled, enqueue it.
   static void decrement_destination_counts(ParCompactionManager* cm,
                                            SpaceId src_space_id,
                                            size_t beg_region,
                                            HeapWord* end_addr);
   // Fill a region, copying objects from one or more source regions.
   static void fill_region(ParCompactionManager* cm, size_t region_idx);
   static void fill_and_update_region(ParCompactionManager* cm, size_t region) {
     fill_region(cm, region);
   }
   // Update the deferred objects in the space.
   static void update_deferred_objects(ParCompactionManager* cm, SpaceId id);
   // Mark pointer and follow contents.
   template <class T>
   static inline void mark_and_follow(ParCompactionManager* cm, T* p);
   static ParMarkBitMap* mark_bitmap() { return &_mark_bitmap; }
   static ParallelCompactData& summary_data() { return _summary_data; }
   static inline void adjust_pointer(oop* p)       { adjust_pointer(p, false); }
   static inline void adjust_pointer(narrowOop* p) { adjust_pointer(p, false); }
   template <class T>
   static inline void adjust_pointer(T* p,
                                     HeapWord* beg_addr,
                                     HeapWord* end_addr);
   // Reference Processing
   static ReferenceProcessor* const ref_processor() { return _ref_processor; }
   // Return the SpaceId for the given address.
   static SpaceId space_id(HeapWord* addr);
   // Time since last full gc (in milliseconds).
   static jlong millis_since_last_gc();
 #ifdef VALIDATE_MARK_SWEEP
   static void track_adjusted_pointer(void* p, bool isroot);
   static void check_adjust_pointer(void* p);
   static void track_interior_pointers(oop obj);
   static void check_interior_pointers();
   static void reset_live_oop_tracking(bool at_perm);
   static void register_live_oop(oop p, size_t size);
   static void validate_live_oop(oop p, size_t size);
   static void live_oop_moved_to(HeapWord* q, size_t size, HeapWord* compaction_top);
   static void compaction_complete();
   // Querying operation of RecordMarkSweepCompaction results.
   // Finds and prints the current base oop and offset for a word
   // within an oop that was live during the last GC. Helpful for
   // tracking down heap stomps.
   static void print_new_location_of_heap_address(HeapWord* q);
 #endif  // #ifdef VALIDATE_MARK_SWEEP
   // Call backs for class unloading
   // Update subklass/sibling/implementor links at end of marking.
   static void revisit_weak_klass_link(ParCompactionManager* cm, Klass* k);
 #ifndef PRODUCT
   // Debugging support.
   static const char* space_names[last_space_id];
   static void print_region_ranges();
   static void print_dense_prefix_stats(const char* const algorithm,
                                        const SpaceId id,
                                        const bool maximum_compaction,
                                        HeapWord* const addr);
   static void summary_phase_msg(SpaceId dst_space_id,
                                 HeapWord* dst_beg, HeapWord* dst_end,
                                 SpaceId src_space_id,
                                 HeapWord* src_beg, HeapWord* src_end);
 #endif  // #ifndef PRODUCT
 #ifdef  ASSERT
   // Sanity check the new location of a word in the heap.
   static inline void check_new_location(HeapWord* old_addr, HeapWord* new_addr);
   // Verify that all the regions have been emptied.
   static void verify_complete(SpaceId space_id);
 #endif  // #ifdef ASSERT
 };
 inline bool PSParallelCompact::mark_obj(oop obj) {
   const int obj_size = obj->size();
   if (mark_bitmap()->mark_obj(obj, obj_size)) {
     _summary_data.add_obj(obj, obj_size);
     return true;
   } else {
     return false;
   }
 }
 template <class T>
 inline void PSParallelCompact::follow_root(ParCompactionManager* cm, T* p) {
   assert(!Universe::heap()->is_in_reserved(p),
          "roots shouldn't be things within the heap");
 #ifdef VALIDATE_MARK_SWEEP
   if (ValidateMarkSweep) {
     guarantee(!_root_refs_stack->contains(p), "should only be in here once");
     _root_refs_stack->push(p);
   }
 #endif
   T heap_oop = oopDesc::load_heap_oop(p);
   if (!oopDesc::is_null(heap_oop)) {
     oop obj = oopDesc::decode_heap_oop_not_null(heap_oop);
     if (mark_bitmap()->is_unmarked(obj)) {
       if (mark_obj(obj)) {
         obj->follow_contents(cm);
       }
     }
   }
   follow_stack(cm);
 }
 template <class T>
 inline void PSParallelCompact::mark_and_follow(ParCompactionManager* cm,
                                                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);
     if (mark_bitmap()->is_unmarked(obj)) {
       if (mark_obj(obj)) {
         obj->follow_contents(cm);
       }
     }
   }
 }
 template <class T>
 inline void PSParallelCompact::mark_and_push(ParCompactionManager* cm, 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);
     if (mark_bitmap()->is_unmarked(obj)) {
       if (mark_obj(obj)) {
         // This thread marked the object and owns the subsequent processing of it.
         cm->save_for_scanning(obj);
       }
     }
   }
 }
 template <class T>
 inline void PSParallelCompact::adjust_pointer(T* p, bool isroot) {
   T heap_oop = oopDesc::load_heap_oop(p);
   if (!oopDesc::is_null(heap_oop)) {
     oop obj     = oopDesc::decode_heap_oop_not_null(heap_oop);
     oop new_obj = (oop)summary_data().calc_new_pointer(obj);
     assert(new_obj != NULL ||                     // is forwarding ptr?
            obj->is_shared(),                      // never forwarded?
            "should be forwarded");
     // Just always do the update unconditionally?
     if (new_obj != NULL) {
       assert(Universe::heap()->is_in_reserved(new_obj),
              "should be in object space");
       oopDesc::encode_store_heap_oop_not_null(p, new_obj);
     }
   }
   VALIDATE_MARK_SWEEP_ONLY(track_adjusted_pointer(p, isroot));
 }
 template <class T>
 inline void PSParallelCompact::KeepAliveClosure::do_oop_work(T* p) {
 #ifdef VALIDATE_MARK_SWEEP
   if (ValidateMarkSweep) {
     if (!Universe::heap()->is_in_reserved(p)) {
       _root_refs_stack->push(p);
     } else {
       _other_refs_stack->push(p);
     }
   }
 #endif
   mark_and_push(_compaction_manager, p);
 }
 inline bool PSParallelCompact::print_phases() {
   return _print_phases;
 }
 inline double PSParallelCompact::normal_distribution(double density) {
   assert(_dwl_initialized, "uninitialized");
   const double squared_term = (density - _dwl_mean) / _dwl_std_dev;
   return _dwl_first_term * exp(-0.5 * squared_term * squared_term);
 }
 inline bool
 PSParallelCompact::dead_space_crosses_boundary(const RegionData* region,
                                                idx_t bit)
 {
   assert(bit > 0, "cannot call this for the first bit/region");
   assert(_summary_data.region_to_addr(region) == _mark_bitmap.bit_to_addr(bit),
          "sanity check");
   // Dead space crosses the boundary if (1) a partial object does not extend
   // onto the region, (2) an object does not start at the beginning of the
   // region, and (3) an object does not end at the end of the prior region.
   return region->partial_obj_size() == 0 &&
     !_mark_bitmap.is_obj_beg(bit) &&
     !_mark_bitmap.is_obj_end(bit - 1);
 }
 inline bool
 PSParallelCompact::is_in(HeapWord* p, HeapWord* beg_addr, HeapWord* end_addr) {
   return p >= beg_addr && p < end_addr;
 }
 inline bool
 PSParallelCompact::is_in(oop* p, HeapWord* beg_addr, HeapWord* end_addr) {
   return is_in((HeapWord*)p, beg_addr, end_addr);
 }
 inline MutableSpace* PSParallelCompact::space(SpaceId id) {
   assert(id < last_space_id, "id out of range");
   return _space_info[id].space();
 }
 inline HeapWord* PSParallelCompact::new_top(SpaceId id) {
   assert(id < last_space_id, "id out of range");
   return _space_info[id].new_top();
 }
 inline HeapWord* PSParallelCompact::dense_prefix(SpaceId id) {
   assert(id < last_space_id, "id out of range");
   return _space_info[id].dense_prefix();
 }
 inline ObjectStartArray* PSParallelCompact::start_array(SpaceId id) {
   assert(id < last_space_id, "id out of range");
   return _space_info[id].start_array();
 }
 inline bool PSParallelCompact::should_update_klass(klassOop k) {
   return ((HeapWord*) k) >= dense_prefix(perm_space_id);
 }
 template <class T>
 inline void PSParallelCompact::adjust_pointer(T* p,
                                               HeapWord* beg_addr,
                                               HeapWord* end_addr) {
   if (is_in((HeapWord*)p, beg_addr, end_addr)) {
     adjust_pointer(p);
   }
 }
 #ifdef ASSERT
 inline void
 PSParallelCompact::check_new_location(HeapWord* old_addr, HeapWord* new_addr)
 {
   assert(old_addr >= new_addr || space_id(old_addr) != space_id(new_addr),
          "must move left or to a different space");
 }
 #endif // ASSERT
 class MoveAndUpdateClosure: public ParMarkBitMapClosure {
  public:
   inline MoveAndUpdateClosure(ParMarkBitMap* bitmap, ParCompactionManager* cm,
                               ObjectStartArray* start_array,
                               HeapWord* destination, size_t words);
   // Accessors.
   HeapWord* destination() const         { return _destination; }
   // If the object will fit (size <= words_remaining()), copy it to the current
   // destination, update the interior oops and the start array and return either
   // full (if the closure is full) or incomplete.  If the object will not fit,
   // return would_overflow.
   virtual IterationStatus do_addr(HeapWord* addr, size_t size);
   // Copy enough words to fill this closure, starting at source().  Interior
   // oops and the start array are not updated.  Return full.
   IterationStatus copy_until_full();
   // Copy enough words to fill this closure or to the end of an object,
   // whichever is smaller, starting at source().  Interior oops and the start
   // array are not updated.
   void copy_partial_obj();
  protected:
   // Update variables to indicate that word_count words were processed.
   inline void update_state(size_t word_count);
  protected:
   ObjectStartArray* const _start_array;
   HeapWord*               _destination;         // Next addr to be written.
 };
 inline
 MoveAndUpdateClosure::MoveAndUpdateClosure(ParMarkBitMap* bitmap,
                                            ParCompactionManager* cm,
                                            ObjectStartArray* start_array,
                                            HeapWord* destination,
                                            size_t words) :
   ParMarkBitMapClosure(bitmap, cm, words), _start_array(start_array)
 {
   _destination = destination;
 }
 inline void MoveAndUpdateClosure::update_state(size_t words)
 {
   decrement_words_remaining(words);
   _source += words;
   _destination += words;
 }
 class UpdateOnlyClosure: public ParMarkBitMapClosure {
  private:
   const PSParallelCompact::SpaceId _space_id;
   ObjectStartArray* const          _start_array;
  public:
   UpdateOnlyClosure(ParMarkBitMap* mbm,
                     ParCompactionManager* cm,
                     PSParallelCompact::SpaceId space_id);
   // Update the object.
   virtual IterationStatus do_addr(HeapWord* addr, size_t words);
   inline void do_addr(HeapWord* addr);
 };
 inline void UpdateOnlyClosure::do_addr(HeapWord* addr)
 {
   _start_array->allocate_block(addr);
   oop(addr)->update_contents(compaction_manager());
 }
 class FillClosure: public ParMarkBitMapClosure
 {
 public:
   FillClosure(ParCompactionManager* cm, PSParallelCompact::SpaceId space_id) :
     ParMarkBitMapClosure(PSParallelCompact::mark_bitmap(), cm),
     _start_array(PSParallelCompact::start_array(space_id))
   {
     assert(space_id == PSParallelCompact::perm_space_id ||
            space_id == PSParallelCompact::old_space_id,
            "cannot use FillClosure in the young gen");
   }
   virtual IterationStatus do_addr(HeapWord* addr, size_t size) {
     CollectedHeap::fill_with_objects(addr, size);
     HeapWord* const end = addr + size;
     do {
       _start_array->allocate_block(addr);
       addr += oop(addr)->size();
     } while (addr < end);
     return ParMarkBitMap::incomplete;
   }
 private:
   ObjectStartArray* const _start_array;
 };

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/gc_implementation/parallelScavenge/psParallelCompact.hpp@0fbdb4381b99 (annotated)

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