1 /*
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   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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   6  * under the terms of the GNU General Public License version 2 only, as
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  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
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  20  * or visit www.oracle.com if you need additional information or have any
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  24 
  25 #ifndef SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_PARMARKBITMAP_HPP
  26 #define SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_PARMARKBITMAP_HPP
  27 
  28 #include "memory/memRegion.hpp"
  29 #include "oops/oop.hpp"
  30 #include "utilities/bitMap.hpp"
  31 

  32 class ParMarkBitMapClosure;
  33 class PSVirtualSpace;
  34 
  35 class ParMarkBitMap: public CHeapObj<mtGC>
  36 {
  37 public:
  38   typedef BitMap::idx_t idx_t;
  39 
  40   // Values returned by the iterate() methods.
  41   enum IterationStatus { incomplete, complete, full, would_overflow };
  42 
  43   inline ParMarkBitMap();

  44   bool initialize(MemRegion covered_region);
  45 
  46   // Atomically mark an object as live.
  47   bool mark_obj(HeapWord* addr, size_t size);
  48   inline bool mark_obj(oop obj, int size);

  49 
  50   // Return whether the specified begin or end bit is set.
  51   inline bool is_obj_beg(idx_t bit) const;
  52   inline bool is_obj_end(idx_t bit) const;
  53 
  54   // Traditional interface for testing whether an object is marked or not (these
  55   // test only the begin bits).
  56   inline bool is_marked(idx_t bit)      const;
  57   inline bool is_marked(HeapWord* addr) const;
  58   inline bool is_marked(oop obj)        const;
  59 
  60   inline bool is_unmarked(idx_t bit)      const;
  61   inline bool is_unmarked(HeapWord* addr) const;
  62   inline bool is_unmarked(oop obj)        const;
  63 
  64   // Convert sizes from bits to HeapWords and back.  An object that is n bits
  65   // long will be bits_to_words(n) words long.  An object that is m words long
  66   // will take up words_to_bits(m) bits in the bitmap.
  67   inline static size_t bits_to_words(idx_t bits);
  68   inline static idx_t  words_to_bits(size_t words);
  69 
  70   // Return the size in words of an object given a begin bit and an end bit, or
  71   // the equivalent beg_addr and end_addr.
  72   inline size_t obj_size(idx_t beg_bit, idx_t end_bit) const;
  73   inline size_t obj_size(HeapWord* beg_addr, HeapWord* end_addr) const;
  74 
  75   // Return the size in words of the object (a search is done for the end bit).
  76   inline size_t obj_size(idx_t beg_bit)  const;
  77   inline size_t obj_size(HeapWord* addr) const;





  78 
  79   // Apply live_closure to each live object that lies completely within the
  80   // range [live_range_beg, live_range_end).  This is used to iterate over the
  81   // compacted region of the heap.  Return values:
  82   //
  83   // incomplete         The iteration is not complete.  The last object that
  84   //                    begins in the range does not end in the range;
  85   //                    closure->source() is set to the start of that object.
  86   //
  87   // complete           The iteration is complete.  All objects in the range
  88   //                    were processed and the closure is not full;
  89   //                    closure->source() is set one past the end of the range.
  90   //
  91   // full               The closure is full; closure->source() is set to one
  92   //                    past the end of the last object processed.
  93   //
  94   // would_overflow     The next object in the range would overflow the closure;
  95   //                    closure->source() is set to the start of that object.
  96   IterationStatus iterate(ParMarkBitMapClosure* live_closure,
  97                           idx_t range_beg, idx_t range_end) const;
  98   inline IterationStatus iterate(ParMarkBitMapClosure* live_closure,
  99                                  HeapWord* range_beg,
 100                                  HeapWord* range_end) const;
 101 
 102   // Apply live closure as above and additionally apply dead_closure to all dead
 103   // space in the range [range_beg, dead_range_end).  Note that dead_range_end
 104   // must be >= range_end.  This is used to iterate over the dense prefix.
 105   //
 106   // This method assumes that if the first bit in the range (range_beg) is not
 107   // marked, then dead space begins at that point and the dead_closure is
 108   // applied.  Thus callers must ensure that range_beg is not in the middle of a
 109   // live object.
 110   IterationStatus iterate(ParMarkBitMapClosure* live_closure,
 111                           ParMarkBitMapClosure* dead_closure,
 112                           idx_t range_beg, idx_t range_end,
 113                           idx_t dead_range_end) const;
 114   inline IterationStatus iterate(ParMarkBitMapClosure* live_closure,
 115                                  ParMarkBitMapClosure* dead_closure,
 116                                  HeapWord* range_beg,
 117                                  HeapWord* range_end,
 118                                  HeapWord* dead_range_end) const;
 119 
 120   // Return the number of live words in the range [beg_addr, end_obj) due to
 121   // objects that start in the range.  If a live object extends onto the range,
 122   // the caller must detect and account for any live words due to that object.
 123   // If a live object extends beyond the end of the range, only the words within
 124   // the range are included in the result. The end of the range must be a live object,
 125   // which is the case when updating pointers.  This allows a branch to be removed



 126   // from inside the loop.
 127   size_t live_words_in_range(HeapWord* beg_addr, oop end_obj) const;
 128 
 129   inline HeapWord* region_start() const;
 130   inline HeapWord* region_end() const;
 131   inline size_t    region_size() const;
 132   inline size_t    size() const;
 133 
 134   // Convert a heap address to/from a bit index.
 135   inline idx_t     addr_to_bit(HeapWord* addr) const;
 136   inline HeapWord* bit_to_addr(idx_t bit) const;
 137 
 138   // Return the bit index of the first marked object that begins (or ends,
 139   // respectively) in the range [beg, end).  If no object is found, return end.
 140   inline idx_t find_obj_beg(idx_t beg, idx_t end) const;
 141   inline idx_t find_obj_end(idx_t beg, idx_t end) const;
 142 
 143   inline HeapWord* find_obj_beg(HeapWord* beg, HeapWord* end) const;
 144   inline HeapWord* find_obj_end(HeapWord* beg, HeapWord* end) const;
 145 
 146   // Clear a range of bits or the entire bitmap (both begin and end bits are
 147   // cleared).
 148   inline void clear_range(idx_t beg, idx_t end);

 149 
 150   // Return the number of bits required to represent the specified number of
 151   // HeapWords, or the specified region.
 152   static inline idx_t bits_required(size_t words);
 153   static inline idx_t bits_required(MemRegion covered_region);
 154   //static inline idx_t words_required(MemRegion covered_region);









 155 
 156   void print_on_error(outputStream* st) const {
 157     st->print_cr("Marking Bits: (ParMarkBitMap*) " PTR_FORMAT, this);
 158     _beg_bits.print_on_error(st, " Begin Bits: ");
 159     _end_bits.print_on_error(st, " End Bits:   ");
 160   }
 161 
 162 #ifdef  ASSERT
 163   void verify_clear() const;
 164   inline void verify_bit(idx_t bit) const;
 165   inline void verify_addr(HeapWord* addr) const;
 166 #endif  // #ifdef ASSERT
 167 
 168 private:
 169   // Each bit in the bitmap represents one unit of 'object granularity.' Objects
 170   // are double-word aligned in 32-bit VMs, but not in 64-bit VMs, so the 32-bit
 171   // granularity is 2, 64-bit is 1.
 172   static inline size_t obj_granularity() { return size_t(MinObjAlignment); }
 173   static inline int obj_granularity_shift() { return LogMinObjAlignment; }
 174 
 175   HeapWord*       _region_start;
 176   size_t          _region_size;
 177   BitMap          _beg_bits;
 178   BitMap          _end_bits;
 179   PSVirtualSpace* _virtual_space;






 180 };
 181 
 182 inline ParMarkBitMap::ParMarkBitMap():
 183   _beg_bits(), _end_bits(), _region_start(NULL), _region_size(0), _virtual_space(NULL)
 184 { }











 185 
 186 inline void ParMarkBitMap::clear_range(idx_t beg, idx_t end)
 187 {
 188   _beg_bits.clear_range(beg, end);
 189   _end_bits.clear_range(beg, end);
 190 }
 191 
 192 inline ParMarkBitMap::idx_t
 193 ParMarkBitMap::bits_required(size_t words)
 194 {
 195   // Need two bits (one begin bit, one end bit) for each unit of 'object
 196   // granularity' in the heap.
 197   return words_to_bits(words * 2);
 198 }
 199 
 200 inline ParMarkBitMap::idx_t
 201 ParMarkBitMap::bits_required(MemRegion covered_region)
 202 {
 203   return bits_required(covered_region.word_size());
 204 }
 205 






 206 inline HeapWord*
 207 ParMarkBitMap::region_start() const
 208 {
 209   return _region_start;
 210 }
 211 
 212 inline HeapWord*
 213 ParMarkBitMap::region_end() const
 214 {
 215   return region_start() + region_size();
 216 }
 217 
 218 inline size_t
 219 ParMarkBitMap::region_size() const
 220 {
 221   return _region_size;
 222 }
 223 
 224 inline size_t
 225 ParMarkBitMap::size() const
 226 {
 227   return _beg_bits.size();
 228 }
 229 
 230 inline bool ParMarkBitMap::is_obj_beg(idx_t bit) const
 231 {
 232   return _beg_bits.at(bit);
 233 }
 234 
 235 inline bool ParMarkBitMap::is_obj_end(idx_t bit) const
 236 {
 237   return _end_bits.at(bit);
 238 }
 239 
 240 inline bool ParMarkBitMap::is_marked(idx_t bit) const
 241 {
 242   return is_obj_beg(bit);
 243 }
 244 
 245 inline bool ParMarkBitMap::is_marked(HeapWord* addr) const
 246 {
 247   return is_marked(addr_to_bit(addr));
 248 }
 249 
 250 inline bool ParMarkBitMap::is_marked(oop obj) const
 251 {
 252   return is_marked((HeapWord*)obj);
 253 }
 254 
 255 inline bool ParMarkBitMap::is_unmarked(idx_t bit) const
 256 {
 257   return !is_marked(bit);
 258 }
 259 
 260 inline bool ParMarkBitMap::is_unmarked(HeapWord* addr) const
 261 {
 262   return !is_marked(addr);
 263 }
 264 
 265 inline bool ParMarkBitMap::is_unmarked(oop obj) const
 266 {
 267   return !is_marked(obj);
 268 }
 269 
 270 inline size_t
 271 ParMarkBitMap::bits_to_words(idx_t bits)
 272 {
 273   return bits << obj_granularity_shift();
 274 }
 275 
 276 inline ParMarkBitMap::idx_t
 277 ParMarkBitMap::words_to_bits(size_t words)
 278 {
 279   return words >> obj_granularity_shift();
 280 }
 281 
 282 inline size_t ParMarkBitMap::obj_size(idx_t beg_bit, idx_t end_bit) const
 283 {
 284   DEBUG_ONLY(verify_bit(beg_bit);)
 285   DEBUG_ONLY(verify_bit(end_bit);)
 286   return bits_to_words(end_bit - beg_bit + 1);
 287 }
 288 
 289 inline size_t
 290 ParMarkBitMap::obj_size(HeapWord* beg_addr, HeapWord* end_addr) const
 291 {
 292   DEBUG_ONLY(verify_addr(beg_addr);)
 293   DEBUG_ONLY(verify_addr(end_addr);)
 294   return pointer_delta(end_addr, beg_addr) + obj_granularity();
 295 }
 296 
 297 inline size_t ParMarkBitMap::obj_size(idx_t beg_bit) const
 298 {
 299   const idx_t end_bit = _end_bits.get_next_one_offset_inline(beg_bit, size());
 300   assert(is_marked(beg_bit), "obj not marked");
 301   assert(end_bit < size(), "end bit missing");
 302   return obj_size(beg_bit, end_bit);
 303 }
 304 
 305 inline size_t ParMarkBitMap::obj_size(HeapWord* addr) const
 306 {
 307   return obj_size(addr_to_bit(addr));
 308 }
 309 





 310 inline ParMarkBitMap::IterationStatus
 311 ParMarkBitMap::iterate(ParMarkBitMapClosure* live_closure,
 312                        HeapWord* range_beg,
 313                        HeapWord* range_end) const
 314 {
 315   return iterate(live_closure, addr_to_bit(range_beg), addr_to_bit(range_end));
 316 }
 317 
 318 inline ParMarkBitMap::IterationStatus
 319 ParMarkBitMap::iterate(ParMarkBitMapClosure* live_closure,
 320                        ParMarkBitMapClosure* dead_closure,
 321                        HeapWord* range_beg,
 322                        HeapWord* range_end,
 323                        HeapWord* dead_range_end) const
 324 {
 325   return iterate(live_closure, dead_closure,
 326                  addr_to_bit(range_beg), addr_to_bit(range_end),
 327                  addr_to_bit(dead_range_end));
 328 }
 329 
 330 inline bool
 331 ParMarkBitMap::mark_obj(oop obj, int size)
 332 {
 333   return mark_obj((HeapWord*)obj, (size_t)size);
 334 }
 335 
 336 inline BitMap::idx_t
 337 ParMarkBitMap::addr_to_bit(HeapWord* addr) const
 338 {
 339   DEBUG_ONLY(verify_addr(addr);)
 340   return words_to_bits(pointer_delta(addr, region_start()));
 341 }
 342 
 343 inline HeapWord*
 344 ParMarkBitMap::bit_to_addr(idx_t bit) const
 345 {
 346   DEBUG_ONLY(verify_bit(bit);)
 347   return region_start() + bits_to_words(bit);
 348 }
 349 
 350 inline ParMarkBitMap::idx_t
 351 ParMarkBitMap::find_obj_beg(idx_t beg, idx_t end) const
 352 {
 353   return _beg_bits.get_next_one_offset_inline_aligned_right(beg, end);
 354 }
 355 
 356 inline ParMarkBitMap::idx_t
 357 ParMarkBitMap::find_obj_end(idx_t beg, idx_t end) const
 358 {
 359   return _end_bits.get_next_one_offset_inline_aligned_right(beg, end);
 360 }
 361 
 362 inline HeapWord*
 363 ParMarkBitMap::find_obj_beg(HeapWord* beg, HeapWord* end) const
 364 {
 365   const idx_t beg_bit = addr_to_bit(beg);
 366   const idx_t end_bit = addr_to_bit(end);
 367   const idx_t search_end = BitMap::word_align_up(end_bit);
 368   const idx_t res_bit = MIN2(find_obj_beg(beg_bit, search_end), end_bit);
 369   return bit_to_addr(res_bit);
 370 }
 371 
 372 inline HeapWord*
 373 ParMarkBitMap::find_obj_end(HeapWord* beg, HeapWord* end) const
 374 {
 375   const idx_t beg_bit = addr_to_bit(beg);
 376   const idx_t end_bit = addr_to_bit(end);
 377   const idx_t search_end = BitMap::word_align_up(end_bit);
 378   const idx_t res_bit = MIN2(find_obj_end(beg_bit, search_end), end_bit);
 379   return bit_to_addr(res_bit);
 380 }
 381 
 382 #ifdef  ASSERT
 383 inline void ParMarkBitMap::verify_bit(idx_t bit) const {
 384   // Allow one past the last valid bit; useful for loop bounds.
 385   assert(bit <= _beg_bits.size(), "bit out of range");
 386 }
 387 
 388 inline void ParMarkBitMap::verify_addr(HeapWord* addr) const {
 389   // Allow one past the last valid address; useful for loop bounds.
 390   assert(addr >= region_start(),
 391       err_msg("addr too small, addr: " PTR_FORMAT " region start: " PTR_FORMAT, addr, region_start()));
 392   assert(addr <= region_end(),
 393       err_msg("addr too big, addr: " PTR_FORMAT " region end: " PTR_FORMAT, addr, region_end()));
 394 }
 395 #endif  // #ifdef ASSERT
 396 
 397 #endif // SHARE_VM_GC_IMPLEMENTATION_PARALLELSCAVENGE_PARMARKBITMAP_HPP
--- EOF ---