--- a/src/share/vm/gc_implementation/parallelScavenge/psParallelCompact.hpp	Mon May 27 12:58:42 2013 +0200
+++ b/src/share/vm/gc_implementation/parallelScavenge/psParallelCompact.hpp	Thu May 30 13:04:51 2013 -0700
@@ -220,6 +220,17 @@
   // Mask for the bits in a pointer to get the address of the start of a region.
   static const size_t RegionAddrMask;
 
+  static const size_t Log2BlockSize;
+  static const size_t BlockSize;
+  static const size_t BlockSizeBytes;
+
+  static const size_t BlockSizeOffsetMask;
+  static const size_t BlockAddrOffsetMask;
+  static const size_t BlockAddrMask;
+
+  static const size_t BlocksPerRegion;
+  static const size_t Log2BlocksPerRegion;
+
   class RegionData
   {
   public:
@@ -272,6 +283,12 @@
     inline uint destination_count() const;
     inline uint destination_count_raw() const;
 
+    // Whether the block table for this region has been filled.
+    inline bool blocks_filled() const;
+
+    // Number of times the block table was filled.
+    DEBUG_ONLY(inline size_t blocks_filled_count() const;)
+
     // The location of the java heap data that corresponds to this region.
     inline HeapWord* data_location() const;
 
@@ -296,6 +313,7 @@
     void set_partial_obj_size(size_t words)    {
       _partial_obj_size = (region_sz_t) words;
     }
+    inline void set_blocks_filled();
 
     inline void set_destination_count(uint count);
     inline void set_live_obj_size(size_t words);
@@ -328,7 +346,11 @@
     HeapWord*            _partial_obj_addr;
     region_sz_t          _partial_obj_size;
     region_sz_t volatile _dc_and_los;
+    bool                 _blocks_filled;
+
 #ifdef ASSERT
+    size_t               _blocks_filled_count;   // Number of block table fills.
+
     // These enable optimizations that are only partially implemented.  Use
     // debug builds to prevent the code fragments from breaking.
     HeapWord*            _data_location;
@@ -337,11 +359,26 @@
 
 #ifdef ASSERT
    public:
-    uint            _pushed;   // 0 until region is pushed onto a worker's stack
+    uint                 _pushed;   // 0 until region is pushed onto a stack
    private:
 #endif
   };
 
+  // "Blocks" allow shorter sections of the bitmap to be searched.  Each Block
+  // holds an offset, which is the amount of live data in the Region to the left
+  // of the first live object that starts in the Block.
+  class BlockData
+  {
+  public:
+    typedef unsigned short int blk_ofs_t;
+
+    blk_ofs_t offset() const    { return _offset; }
+    void set_offset(size_t val) { _offset = (blk_ofs_t)val; }
+
+  private:
+    blk_ofs_t _offset;
+  };
+
 public:
   ParallelCompactData();
   bool initialize(MemRegion covered_region);
@@ -353,8 +390,9 @@
   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);
+  size_t block_count() const { return _block_count; }
+  inline BlockData* block(size_t block_idx) const;
+  inline size_t     block(const BlockData* block_ptr) const;
 
   void add_obj(HeapWord* addr, size_t len);
   void add_obj(oop p, size_t len) { add_obj((HeapWord*)p, len); }
@@ -394,11 +432,24 @@
   inline HeapWord*  region_align_up(HeapWord* addr) const;
   inline bool       is_region_aligned(HeapWord* addr) const;
 
+  // Analogous to region_offset() for blocks.
+  size_t     block_offset(const HeapWord* addr) const;
+  size_t     addr_to_block_idx(const HeapWord* addr) const;
+  size_t     addr_to_block_idx(const oop obj) const {
+    return addr_to_block_idx((HeapWord*) obj);
+  }
+  inline BlockData* addr_to_block_ptr(const HeapWord* addr) const;
+  inline HeapWord*  block_to_addr(size_t block) const;
+  inline size_t     region_to_block_idx(size_t region) const;
+
+  inline HeapWord*  block_align_down(HeapWord* addr) const;
+  inline HeapWord*  block_align_up(HeapWord* addr) const;
+  inline bool       is_block_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.
+  // Return the location of the object after compaction.
   HeapWord* calc_new_pointer(HeapWord* addr);
 
   HeapWord* calc_new_pointer(oop p) {
@@ -411,6 +462,7 @@
 #endif  // #ifdef ASSERT
 
 private:
+  bool initialize_block_data();
   bool initialize_region_data(size_t region_size);
   PSVirtualSpace* create_vspace(size_t count, size_t element_size);
 
@@ -424,6 +476,10 @@
   size_t          _reserved_byte_size;
   RegionData*     _region_data;
   size_t          _region_count;
+
+  PSVirtualSpace* _block_vspace;
+  BlockData*      _block_data;
+  size_t          _block_count;
 };
 
 inline uint
@@ -438,6 +494,28 @@
   return destination_count_raw() >> dc_shift;
 }
 
+inline bool
+ParallelCompactData::RegionData::blocks_filled() const
+{
+  return _blocks_filled;
+}
+
+#ifdef ASSERT
+inline size_t
+ParallelCompactData::RegionData::blocks_filled_count() const
+{
+  return _blocks_filled_count;
+}
+#endif // #ifdef ASSERT
+
+inline void
+ParallelCompactData::RegionData::set_blocks_filled()
+{
+  _blocks_filled = true;
+  // Debug builds count the number of times the table was filled.
+  DEBUG_ONLY(Atomic::inc_ptr(&_blocks_filled_count));
+}
+
 inline void
 ParallelCompactData::RegionData::set_destination_count(uint count)
 {
@@ -532,6 +610,12 @@
   return pointer_delta(region_ptr, _region_data, sizeof(RegionData));
 }
 
+inline ParallelCompactData::BlockData*
+ParallelCompactData::block(size_t n) const {
+  assert(n < block_count(), "bad arg");
+  return _block_data + n;
+}
+
 inline size_t
 ParallelCompactData::region_offset(const HeapWord* addr) const
 {
@@ -598,6 +682,63 @@
   return region_offset(addr) == 0;
 }
 
+inline size_t
+ParallelCompactData::block_offset(const HeapWord* addr) const
+{
+  assert(addr >= _region_start, "bad addr");
+  assert(addr <= _region_end, "bad addr");
+  return (size_t(addr) & BlockAddrOffsetMask) >> LogHeapWordSize;
+}
+
+inline size_t
+ParallelCompactData::addr_to_block_idx(const HeapWord* addr) const
+{
+  assert(addr >= _region_start, "bad addr");
+  assert(addr <= _region_end, "bad addr");
+  return pointer_delta(addr, _region_start) >> Log2BlockSize;
+}
+
+inline ParallelCompactData::BlockData*
+ParallelCompactData::addr_to_block_ptr(const HeapWord* addr) const
+{
+  return block(addr_to_block_idx(addr));
+}
+
+inline HeapWord*
+ParallelCompactData::block_to_addr(size_t block) const
+{
+  assert(block < _block_count, "block out of range");
+  return _region_start + (block << Log2BlockSize);
+}
+
+inline size_t
+ParallelCompactData::region_to_block_idx(size_t region) const
+{
+  return region << Log2BlocksPerRegion;
+}
+
+inline HeapWord*
+ParallelCompactData::block_align_down(HeapWord* addr) const
+{
+  assert(addr >= _region_start, "bad addr");
+  assert(addr < _region_end + RegionSize, "bad addr");
+  return (HeapWord*)(size_t(addr) & BlockAddrMask);
+}
+
+inline HeapWord*
+ParallelCompactData::block_align_up(HeapWord* addr) const
+{
+  assert(addr >= _region_start, "bad addr");
+  assert(addr <= _region_end, "bad addr");
+  return block_align_down(addr + BlockSizeOffsetMask);
+}
+
+inline bool
+ParallelCompactData::is_block_aligned(HeapWord* addr) const
+{
+  return block_offset(addr) == 0;
+}
+
 // Abstract closure for use with ParMarkBitMap::iterate(), which will invoke the
 // do_addr() method.
 //
@@ -775,6 +916,7 @@
   // Convenient access to type names.
   typedef ParMarkBitMap::idx_t idx_t;
   typedef ParallelCompactData::RegionData RegionData;
+  typedef ParallelCompactData::BlockData BlockData;
 
   typedef enum {
     old_space_id, eden_space_id,
@@ -962,6 +1104,8 @@
   // Adjust addresses in roots.  Does not adjust addresses in heap.
   static void adjust_roots();
 
+  DEBUG_ONLY(static void write_block_fill_histogram(outputStream* const out);)
+
   // Move objects to new locations.
   static void compact_perm(ParCompactionManager* cm);
   static void compact();
@@ -1128,6 +1272,9 @@
     fill_region(cm, region);
   }
 
+  // Fill in the block table for the specified region.
+  static void fill_blocks(size_t region_idx);
+
   // Update the deferred objects in the space.
   static void update_deferred_objects(ParCompactionManager* cm, SpaceId id);