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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  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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  24 
  25 #ifndef SHARE_VM_UTILITIES_BITMAP_HPP
  26 #define SHARE_VM_UTILITIES_BITMAP_HPP
  27 
  28 #include "memory/allocation.hpp"
  29 #include "utilities/align.hpp"
  30 
  31 // Forward decl;
  32 class BitMapClosure;
  33 
  34 // Operations for bitmaps represented as arrays of unsigned integers.
  35 // Bit offsets are numbered from 0 to size-1.
  36 
  37 // The "abstract" base BitMap class.
  38 //
  39 // The constructor and destructor are protected to prevent
  40 // creation of BitMap instances outside of the BitMap class.
  41 //
  42 // The BitMap class doesn't use virtual calls on purpose,
  43 // this ensures that we don't get a vtable unnecessarily.
  44 //
  45 // The allocation of the backing storage for the BitMap are handled by
  46 // the subclasses. BitMap doesn't allocate or delete backing storage.
  47 class BitMap {
  48   friend class BitMap2D;
  49 
  50  public:
  51   typedef size_t idx_t;         // Type used for bit and word indices.
  52   typedef uintptr_t bm_word_t;  // Element type of array that represents
  53                                 // the bitmap.
  54 
  55   // Hints for range sizes.
  56   typedef enum {
  57     unknown_range, small_range, large_range
  58   } RangeSizeHint;
  59 
  60  private:
  61   bm_word_t* _map;     // First word in bitmap
  62   idx_t      _size;    // Size of bitmap (in bits)
  63 
  64   // Helper for get_next_{zero,one}_bit variants.
  65   // - flip designates whether searching for 1s or 0s.  Must be one of
  66   //   find_{zeros,ones}_flip.
  67   // - aligned_right is true if r_index is a priori on a bm_word_t boundary.
  68   template<bm_word_t flip, bool aligned_right>
  69   inline idx_t get_next_bit_impl(idx_t l_index, idx_t r_index) const;
  70 
  71   // Values for get_next_bit_impl flip parameter.
  72   static const bm_word_t find_ones_flip = 0;
  73   static const bm_word_t find_zeros_flip = ~(bm_word_t)0;
  74 
  75   // Threshold for performing small range operation, even when large range
  76   // operation was requested. Measured in words.
  77   static const size_t small_range_words = 32;
  78 
  79  protected:
  80   // Return the position of bit within the word that contains it (e.g., if
  81   // bitmap words are 32 bits, return a number 0 <= n <= 31).
  82   static idx_t bit_in_word(idx_t bit) { return bit & (BitsPerWord - 1); }
  83 
  84   // Return a mask that will select the specified bit, when applied to the word
  85   // containing the bit.
  86   static bm_word_t bit_mask(idx_t bit) { return (bm_word_t)1 << bit_in_word(bit); }
  87 
  88   // Return the index of the word containing the specified bit.
  89   static idx_t word_index(idx_t bit)  { return bit >> LogBitsPerWord; }
  90 
  91   // Return the bit number of the first bit in the specified word.
  92   static idx_t bit_index(idx_t word)  { return word << LogBitsPerWord; }
  93 
  94   // Return the array of bitmap words, or a specific word from it.
  95   bm_word_t* map()                 { return _map; }
  96   const bm_word_t* map() const     { return _map; }
  97   bm_word_t  map(idx_t word) const { return _map[word]; }
  98 
  99   // Return a pointer to the word containing the specified bit.
 100   bm_word_t* word_addr(idx_t bit)             { return map() + word_index(bit); }
 101   const bm_word_t* word_addr(idx_t bit) const { return map() + word_index(bit); }
 102 
 103   // Set a word to a specified value or to all ones; clear a word.
 104   void set_word  (idx_t word, bm_word_t val) { _map[word] = val; }
 105   void set_word  (idx_t word)            { set_word(word, ~(bm_word_t)0); }
 106   void clear_word(idx_t word)            { _map[word] = 0; }
 107 
 108   // Utilities for ranges of bits.  Ranges are half-open [beg, end).
 109 
 110   // Ranges within a single word.
 111   bm_word_t inverted_bit_mask_for_range(idx_t beg, idx_t end) const;
 112   void  set_range_within_word      (idx_t beg, idx_t end);
 113   void  clear_range_within_word    (idx_t beg, idx_t end);
 114   void  par_put_range_within_word  (idx_t beg, idx_t end, bool value);
 115 
 116   // Ranges spanning entire words.
 117   void      set_range_of_words         (idx_t beg, idx_t end);
 118   void      clear_range_of_words       (idx_t beg, idx_t end);
 119   void      set_large_range_of_words   (idx_t beg, idx_t end);
 120   void      clear_large_range_of_words (idx_t beg, idx_t end);
 121 
 122   static void clear_range_of_words(bm_word_t* map, idx_t beg, idx_t end);
 123 
 124   static bool is_small_range_of_words(idx_t beg_full_word, idx_t end_full_word);
 125 
 126   // The index of the first full word in a range.
 127   idx_t word_index_round_up(idx_t bit) const;
 128 
 129   // Verification.
 130   void verify_index(idx_t index) const NOT_DEBUG_RETURN;
 131   void verify_range(idx_t beg_index, idx_t end_index) const NOT_DEBUG_RETURN;
 132 
 133   // Statistics.
 134   static const idx_t* _pop_count_table;
 135   static void init_pop_count_table();
 136   static idx_t num_set_bits(bm_word_t w);
 137   static idx_t num_set_bits_from_table(unsigned char c);
 138 
 139   // Allocation Helpers.
 140 
 141   // Allocates and clears the bitmap memory.
 142   template <class Allocator>
 143   static bm_word_t* allocate(const Allocator&, idx_t size_in_bits, bool clear = true);
 144 
 145   // Reallocates and clears the new bitmap memory.
 146   template <class Allocator>
 147   static bm_word_t* reallocate(const Allocator&, bm_word_t* map, idx_t old_size_in_bits, idx_t new_size_in_bits, bool clear = true);
 148 
 149   // Free the bitmap memory.
 150   template <class Allocator>
 151   static void free(const Allocator&, bm_word_t* map, idx_t size_in_bits);
 152 
 153   // Protected functions, that are used by BitMap sub-classes that support them.
 154 
 155   // Resize the backing bitmap memory.
 156   //
 157   // Old bits are transfered to the new memory
 158   // and the extended memory is cleared.
 159   template <class Allocator>
 160   void resize(const Allocator& allocator, idx_t new_size_in_bits);
 161 
 162   // Set up and clear the bitmap memory.
 163   //
 164   // Precondition: The bitmap was default constructed and has
 165   // not yet had memory allocated via resize or (re)initialize.
 166   template <class Allocator>
 167   void initialize(const Allocator& allocator, idx_t size_in_bits);
 168 
 169   // Set up and clear the bitmap memory.
 170   //
 171   // Can be called on previously initialized bitmaps.
 172   template <class Allocator>
 173   void reinitialize(const Allocator& allocator, idx_t new_size_in_bits);
 174 
 175   // Set the map and size.
 176   void update(bm_word_t* map, idx_t size) {
 177     _map = map;
 178     _size = size;
 179   }
 180 
 181   // Protected constructor and destructor.
 182   BitMap(bm_word_t* map, idx_t size_in_bits) : _map(map), _size(size_in_bits) {}
 183   ~BitMap() {}
 184 
 185  public:
 186   // Pretouch the entire range of memory this BitMap covers.
 187   void pretouch();
 188 
 189   // Accessing
 190   static idx_t calc_size_in_words(size_t size_in_bits) {
 191     return word_index(size_in_bits + BitsPerWord - 1);
 192   }
 193 
 194   static idx_t calc_size_in_bytes(size_t size_in_bits) {
 195     return calc_size_in_words(size_in_bits) * BytesPerWord;
 196   }
 197 
 198   idx_t size() const          { return _size; }
 199   idx_t size_in_words() const { return calc_size_in_words(size()); }
 200   idx_t size_in_bytes() const { return calc_size_in_bytes(size()); }
 201 
 202   bool at(idx_t index) const {
 203     verify_index(index);
 204     return (*word_addr(index) & bit_mask(index)) != 0;
 205   }
 206 
 207   // Align bit index up or down to the next bitmap word boundary, or check
 208   // alignment.
 209   static idx_t word_align_up(idx_t bit) {
 210     return align_up(bit, BitsPerWord);
 211   }
 212   static idx_t word_align_down(idx_t bit) {
 213     return align_down(bit, BitsPerWord);
 214   }
 215   static bool is_word_aligned(idx_t bit) {
 216     return word_align_up(bit) == bit;
 217   }
 218 
 219   // Set or clear the specified bit.
 220   inline void set_bit(idx_t bit);
 221   inline void clear_bit(idx_t bit);
 222 
 223   // Atomically set or clear the specified bit.
 224   inline bool par_set_bit(idx_t bit);
 225   inline bool par_clear_bit(idx_t bit);
 226 
 227   // Put the given value at the given offset. The parallel version
 228   // will CAS the value into the bitmap and is quite a bit slower.
 229   // The parallel version also returns a value indicating if the
 230   // calling thread was the one that changed the value of the bit.
 231   void at_put(idx_t index, bool value);
 232   bool par_at_put(idx_t index, bool value);
 233 
 234   // Update a range of bits.  Ranges are half-open [beg, end).
 235   void set_range   (idx_t beg, idx_t end);
 236   void clear_range (idx_t beg, idx_t end);
 237   void set_large_range   (idx_t beg, idx_t end);
 238   void clear_large_range (idx_t beg, idx_t end);
 239   void at_put_range(idx_t beg, idx_t end, bool value);
 240   void par_at_put_range(idx_t beg, idx_t end, bool value);
 241   void at_put_large_range(idx_t beg, idx_t end, bool value);
 242   void par_at_put_large_range(idx_t beg, idx_t end, bool value);
 243 
 244   // Update a range of bits, using a hint about the size.  Currently only
 245   // inlines the predominant case of a 1-bit range.  Works best when hint is a
 246   // compile-time constant.
 247   void set_range(idx_t beg, idx_t end, RangeSizeHint hint);
 248   void clear_range(idx_t beg, idx_t end, RangeSizeHint hint);
 249   void par_set_range(idx_t beg, idx_t end, RangeSizeHint hint);
 250   void par_clear_range  (idx_t beg, idx_t end, RangeSizeHint hint);
 251 
 252   // Clearing
 253   void clear_large();
 254   inline void clear();
 255 
 256   // Iteration support.  Returns "true" if the iteration completed, false
 257   // if the iteration terminated early (because the closure "blk" returned
 258   // false).
 259   bool iterate(BitMapClosure* blk, idx_t leftIndex, idx_t rightIndex);
 260   bool iterate(BitMapClosure* blk) {
 261     // call the version that takes an interval
 262     return iterate(blk, 0, size());
 263   }
 264 
 265   // Looking for 1's and 0's at indices equal to or greater than "l_index",
 266   // stopping if none has been found before "r_index", and returning
 267   // "r_index" (which must be at most "size") in that case.
 268   idx_t get_next_one_offset (idx_t l_index, idx_t r_index) const;
 269   idx_t get_next_zero_offset(idx_t l_index, idx_t r_index) const;
 270 
 271   idx_t get_next_one_offset(idx_t offset) const {
 272     return get_next_one_offset(offset, size());
 273   }
 274   idx_t get_next_zero_offset(idx_t offset) const {
 275     return get_next_zero_offset(offset, size());
 276   }
 277 
 278   // Like "get_next_one_offset", except requires that "r_index" is
 279   // aligned to bitsizeof(bm_word_t).
 280   idx_t get_next_one_offset_aligned_right(idx_t l_index, idx_t r_index) const;
 281 
 282   // Returns the number of bits set in the bitmap.
 283   idx_t count_one_bits() const;
 284 
 285   // Set operations.
 286   void set_union(const BitMap& bits);
 287   void set_difference(const BitMap& bits);
 288   void set_intersection(const BitMap& bits);
 289   // Returns true iff "this" is a superset of "bits".
 290   bool contains(const BitMap& bits) const;
 291   // Returns true iff "this and "bits" have a non-empty intersection.
 292   bool intersects(const BitMap& bits) const;
 293 
 294   // Returns result of whether this map changed
 295   // during the operation
 296   bool set_union_with_result(const BitMap& bits);
 297   bool set_difference_with_result(const BitMap& bits);
 298   bool set_intersection_with_result(const BitMap& bits);
 299 
 300   void set_from(const BitMap& bits);
 301 
 302   bool is_same(const BitMap& bits) const;
 303 
 304   // Test if all bits are set or cleared
 305   bool is_full() const;
 306   bool is_empty() const;
 307 
 308   void write_to(bm_word_t* buffer, size_t buffer_size_in_bytes) const;
 309   void print_on_error(outputStream* st, const char* prefix) const;
 310 
 311 #ifndef PRODUCT
 312  public:
 313   // Printing
 314   void print_on(outputStream* st) const;
 315 #endif
 316 };
 317 
 318 // A concrete implementation of the the "abstract" BitMap class.
 319 //
 320 // The BitMapView is used when the backing storage is managed externally.
 321 class BitMapView : public BitMap {
 322  public:
 323   BitMapView() : BitMap(NULL, 0) {}
 324   BitMapView(bm_word_t* map, idx_t size_in_bits) : BitMap(map, size_in_bits) {}
 325 };
 326 
 327 // A BitMap with storage in a ResourceArea.
 328 class ResourceBitMap : public BitMap {
 329 
 330  public:
 331   ResourceBitMap() : BitMap(NULL, 0) {}
 332   // Clears the bitmap memory.
 333   ResourceBitMap(idx_t size_in_bits);
 334 
 335   // Resize the backing bitmap memory.
 336   //
 337   // Old bits are transfered to the new memory
 338   // and the extended memory is cleared.
 339   void resize(idx_t new_size_in_bits);
 340 
 341   // Set up and clear the bitmap memory.
 342   //
 343   // Precondition: The bitmap was default constructed and has
 344   // not yet had memory allocated via resize or initialize.
 345   void initialize(idx_t size_in_bits);
 346 
 347   // Set up and clear the bitmap memory.
 348   //
 349   // Can be called on previously initialized bitmaps.
 350   void reinitialize(idx_t size_in_bits);
 351 };
 352 
 353 // A BitMap with storage in a specific Arena.
 354 class ArenaBitMap : public BitMap {
 355  public:
 356   // Clears the bitmap memory.
 357   ArenaBitMap(Arena* arena, idx_t size_in_bits);
 358 
 359  private:
 360   // Don't allow copy or assignment.
 361   ArenaBitMap(const ArenaBitMap&);
 362   ArenaBitMap& operator=(const ArenaBitMap&);
 363 };
 364 
 365 // A BitMap with storage in the CHeap.
 366 class CHeapBitMap : public BitMap {
 367 
 368  private:
 369   // Don't allow copy or assignment, to prevent the
 370   // allocated memory from leaking out to other instances.
 371   CHeapBitMap(const CHeapBitMap&);
 372   CHeapBitMap& operator=(const CHeapBitMap&);
 373 
 374   // NMT memory type
 375   MEMFLAGS _flags;
 376 
 377  public:
 378   CHeapBitMap(MEMFLAGS flags = mtInternal) : BitMap(NULL, 0), _flags(flags) {}
 379   // Clears the bitmap memory.
 380   CHeapBitMap(idx_t size_in_bits, MEMFLAGS flags = mtInternal, bool clear = true);
 381   ~CHeapBitMap();
 382 
 383   // Resize the backing bitmap memory.
 384   //
 385   // Old bits are transfered to the new memory
 386   // and the extended memory is cleared.
 387   void resize(idx_t new_size_in_bits);
 388 
 389   // Set up and clear the bitmap memory.
 390   //
 391   // Precondition: The bitmap was default constructed and has
 392   // not yet had memory allocated via resize or initialize.
 393   void initialize(idx_t size_in_bits);
 394 
 395   // Set up and clear the bitmap memory.
 396   //
 397   // Can be called on previously initialized bitmaps.
 398   void reinitialize(idx_t size_in_bits);
 399 };
 400 
 401 // Convenience class wrapping BitMap which provides multiple bits per slot.
 402 class BitMap2D {
 403  public:
 404   typedef BitMap::idx_t idx_t;          // Type used for bit and word indices.
 405   typedef BitMap::bm_word_t bm_word_t;  // Element type of array that
 406                                         // represents the bitmap.
 407  private:
 408   ResourceBitMap _map;
 409   idx_t          _bits_per_slot;
 410 
 411   idx_t bit_index(idx_t slot_index, idx_t bit_within_slot_index) const {
 412     return slot_index * _bits_per_slot + bit_within_slot_index;
 413   }
 414 
 415   void verify_bit_within_slot_index(idx_t index) const {
 416     assert(index < _bits_per_slot, "bit_within_slot index out of bounds");
 417   }
 418 
 419  public:
 420   // Construction. bits_per_slot must be greater than 0.
 421   BitMap2D(idx_t bits_per_slot) :
 422       _map(), _bits_per_slot(bits_per_slot) {}
 423 
 424   // Allocates necessary data structure in resource area. bits_per_slot must be greater than 0.
 425   BitMap2D(idx_t size_in_slots, idx_t bits_per_slot) :
 426       _map(size_in_slots * bits_per_slot), _bits_per_slot(bits_per_slot) {}
 427 
 428   idx_t size_in_bits() {
 429     return _map.size();
 430   }
 431 
 432   // Returns number of full slots that have been allocated
 433   idx_t size_in_slots() {
 434     // Round down
 435     return _map.size() / _bits_per_slot;
 436   }
 437 
 438   bool is_valid_index(idx_t slot_index, idx_t bit_within_slot_index);
 439   bool at(idx_t slot_index, idx_t bit_within_slot_index) const;
 440   void set_bit(idx_t slot_index, idx_t bit_within_slot_index);
 441   void clear_bit(idx_t slot_index, idx_t bit_within_slot_index);
 442   void at_put(idx_t slot_index, idx_t bit_within_slot_index, bool value);
 443   void at_put_grow(idx_t slot_index, idx_t bit_within_slot_index, bool value);
 444 };
 445 
 446 // Closure for iterating over BitMaps
 447 
 448 class BitMapClosure {
 449  public:
 450   // Callback when bit in map is set.  Should normally return "true";
 451   // return of false indicates that the bitmap iteration should terminate.
 452   virtual bool do_bit(BitMap::idx_t offset) = 0;
 453 };
 454 
 455 #endif // SHARE_VM_UTILITIES_BITMAP_HPP