1 /*
   2  * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
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   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  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).
  14  *
  15  * You should have received a copy of the GNU General Public License version
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  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
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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/top.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 class BitMap VALUE_OBJ_CLASS_SPEC {
  38   friend class BitMap2D;
  39   friend class BitMapIterator;
  40 
  41  public:
  42   typedef size_t idx_t;         // Type used for bit and word indices.
  43   typedef uintptr_t bm_word_t;  // Element type of array that represents
  44                                 // the bitmap.
  45 
  46   // Hints for range sizes.
  47   typedef enum {
  48     unknown_range, small_range, large_range
  49   } RangeSizeHint;
  50 
  51  private:
  52   ArrayAllocator<bm_word_t, mtInternal> _map_allocator;
  53   bm_word_t* _map;     // First word in bitmap
  54   idx_t      _size;    // Size of bitmap (in bits)
  55 
  56   // Puts the given value at the given offset, using resize() to size
  57   // the bitmap appropriately if needed using factor-of-two expansion.
  58   void at_put_grow(idx_t index, bool value);
  59 
  60  protected:
  61   // Return the position of bit within the word that contains it (e.g., if
  62   // bitmap words are 32 bits, return a number 0 <= n <= 31).
  63   static idx_t bit_in_word(idx_t bit) { return bit & (BitsPerWord - 1); }
  64 
  65   // Return a mask that will select the specified bit, when applied to the word
  66   // containing the bit.
  67   static bm_word_t bit_mask(idx_t bit) { return (bm_word_t)1 << bit_in_word(bit); }
  68 
  69   // Return the index of the word containing the specified bit.
  70   static idx_t word_index(idx_t bit)  { return bit >> LogBitsPerWord; }
  71 
  72   // Return the bit number of the first bit in the specified word.
  73   static idx_t bit_index(idx_t word)  { return word << LogBitsPerWord; }
  74 
  75   // Return the array of bitmap words, or a specific word from it.
  76   bm_word_t* map() const           { return _map; }
  77   bm_word_t  map(idx_t word) const { return _map[word]; }
  78 
  79   // Return a pointer to the word containing the specified bit.
  80   bm_word_t* word_addr(idx_t bit) const { return map() + word_index(bit); }
  81 
  82   // Set a word to a specified value or to all ones; clear a word.
  83   void set_word  (idx_t word, bm_word_t val) { _map[word] = val; }
  84   void set_word  (idx_t word)            { set_word(word, ~(bm_word_t)0); }
  85   void clear_word(idx_t word)            { _map[word] = 0; }
  86 
  87   // Utilities for ranges of bits.  Ranges are half-open [beg, end).
  88 
  89   // Ranges within a single word.
  90   bm_word_t inverted_bit_mask_for_range(idx_t beg, idx_t end) const;
  91   void  set_range_within_word      (idx_t beg, idx_t end);
  92   void  clear_range_within_word    (idx_t beg, idx_t end);
  93   void  par_put_range_within_word  (idx_t beg, idx_t end, bool value);
  94 
  95   // Ranges spanning entire words.
  96   void      set_range_of_words         (idx_t beg, idx_t end);
  97   void      clear_range_of_words       (idx_t beg, idx_t end);
  98   void      set_large_range_of_words   (idx_t beg, idx_t end);
  99   void      clear_large_range_of_words (idx_t beg, idx_t end);
 100 
 101   // The index of the first full word in a range.
 102   idx_t word_index_round_up(idx_t bit) const;
 103 
 104   // Verification.
 105   inline void verify_index(idx_t index) const NOT_DEBUG_RETURN;
 106   inline void verify_range(idx_t beg_index, idx_t end_index) const
 107     NOT_DEBUG_RETURN;
 108 
 109   // Statistics.
 110   static idx_t* _pop_count_table;
 111   static void init_pop_count_table();
 112   static idx_t num_set_bits(bm_word_t w);
 113   static idx_t num_set_bits_from_table(unsigned char c);
 114 
 115  public:
 116 
 117   // Constructs a bitmap with no map, and size 0.
 118   BitMap() : _map(NULL), _size(0), _map_allocator(false) {}
 119 
 120   // Constructs a bitmap with the given map and size.
 121   BitMap(bm_word_t* map, idx_t size_in_bits);
 122 
 123   // Constructs an empty bitmap of the given size (that is, this clears the
 124   // new bitmap).  Allocates the map array in resource area if
 125   // "in_resource_area" is true, else in the C heap.
 126   BitMap(idx_t size_in_bits, bool in_resource_area = true);
 127 
 128   // Set the map and size.
 129   void set_map(bm_word_t* map)      { _map = map; }
 130   void set_size(idx_t size_in_bits) { _size = size_in_bits; }
 131 
 132   // Allocates necessary data structure, either in the resource area
 133   // or in the C heap, as indicated by "in_resource_area."
 134   // Preserves state currently in bit map by copying data.
 135   // Zeros any newly-addressable bits.
 136   // If "in_resource_area" is false, frees the current map.
 137   // (Note that this assumes that all calls to "resize" on the same BitMap
 138   // use the same value for "in_resource_area".)
 139   void resize(idx_t size_in_bits, bool in_resource_area = true);
 140 
 141   // Accessing
 142   idx_t size() const                    { return _size; }
 143   idx_t size_in_words() const           {
 144     return word_index(size() + BitsPerWord - 1);
 145   }
 146 
 147   bool at(idx_t index) const {
 148     verify_index(index);
 149     return (*word_addr(index) & bit_mask(index)) != 0;
 150   }
 151 
 152   // Align bit index up or down to the next bitmap word boundary, or check
 153   // alignment.
 154   static idx_t word_align_up(idx_t bit) {
 155     return align_size_up(bit, BitsPerWord);
 156   }
 157   static idx_t word_align_down(idx_t bit) {
 158     return align_size_down(bit, BitsPerWord);
 159   }
 160   static bool is_word_aligned(idx_t bit) {
 161     return word_align_up(bit) == bit;
 162   }
 163 
 164   // Set or clear the specified bit.
 165   inline void set_bit(idx_t bit);
 166   inline void clear_bit(idx_t bit);
 167 
 168    // Set or clear the specified bit with result
 169   inline bool set_bit_with_result(idx_t bit);
 170   inline bool clear_bit_with_result(idx_t bit);
 171 
 172   // Atomically set or clear the specified bit.
 173   inline bool par_set_bit(idx_t bit);
 174   inline bool par_clear_bit(idx_t bit);
 175 
 176   // Put the given value at the given offset. The parallel version
 177   // will CAS the value into the bitmap and is quite a bit slower.
 178   // The parallel version also returns a value indicating if the
 179   // calling thread was the one that changed the value of the bit.
 180   void at_put(idx_t index, bool value);
 181   bool par_at_put(idx_t index, bool value);
 182 
 183   // Update a range of bits.  Ranges are half-open [beg, end).
 184   void set_range   (idx_t beg, idx_t end);
 185   void clear_range (idx_t beg, idx_t end);
 186   void set_large_range   (idx_t beg, idx_t end);
 187   void clear_large_range (idx_t beg, idx_t end);
 188   void at_put_range(idx_t beg, idx_t end, bool value);
 189   void par_at_put_range(idx_t beg, idx_t end, bool value);
 190   void at_put_large_range(idx_t beg, idx_t end, bool value);
 191   void par_at_put_large_range(idx_t beg, idx_t end, bool value);
 192 
 193   // Update a range of bits, using a hint about the size.  Currently only
 194   // inlines the predominant case of a 1-bit range.  Works best when hint is a
 195   // compile-time constant.
 196   void set_range(idx_t beg, idx_t end, RangeSizeHint hint);
 197   void clear_range(idx_t beg, idx_t end, RangeSizeHint hint);
 198   void par_set_range(idx_t beg, idx_t end, RangeSizeHint hint);
 199   void par_clear_range  (idx_t beg, idx_t end, RangeSizeHint hint);
 200 
 201   // Clearing
 202   void clear_large();
 203   inline void clear();
 204 
 205   // Iteration support.  Returns "true" if the iteration completed, false
 206   // if the iteration terminated early (because the closure "blk" returned
 207   // false).
 208   bool iterate(BitMapClosure* blk, idx_t leftIndex, idx_t rightIndex);
 209   bool iterate(BitMapClosure* blk) {
 210     // call the version that takes an interval
 211     return iterate(blk, 0, size());
 212   }
 213 
 214   // Looking for 1's and 0's at indices equal to or greater than "l_index",
 215   // stopping if none has been found before "r_index", and returning
 216   // "r_index" (which must be at most "size") in that case.
 217   idx_t get_next_one_offset_inline (idx_t l_index, idx_t r_index) const;
 218   idx_t get_next_zero_offset_inline(idx_t l_index, idx_t r_index) const;
 219 
 220   // Like "get_next_one_offset_inline", except requires that "r_index" is
 221   // aligned to bitsizeof(bm_word_t).
 222   idx_t get_next_one_offset_inline_aligned_right(idx_t l_index,
 223                                                         idx_t r_index) const;
 224 
 225   // Non-inline versionsof the above.
 226   idx_t get_next_one_offset (idx_t l_index, idx_t r_index) const;
 227   idx_t get_next_zero_offset(idx_t l_index, idx_t r_index) const;
 228 
 229   idx_t get_next_one_offset(idx_t offset) const {
 230     return get_next_one_offset(offset, size());
 231   }
 232   idx_t get_next_zero_offset(idx_t offset) const {
 233     return get_next_zero_offset(offset, size());
 234   }
 235 
 236   // Returns the number of bits set in the bitmap.
 237   idx_t count_one_bits() const;
 238 
 239   // Set operations.
 240   void set_union(BitMap bits);
 241   void set_difference(BitMap bits);
 242   void set_intersection(BitMap bits);
 243   // Returns true iff "this" is a superset of "bits".
 244   bool contains(const BitMap bits) const;
 245   // Returns true iff "this and "bits" have a non-empty intersection.
 246   bool intersects(const BitMap bits) const;
 247 
 248   // Returns result of whether this map changed
 249   // during the operation
 250   bool set_union_with_result(BitMap bits);
 251   bool set_difference_with_result(BitMap bits);
 252   bool set_intersection_with_result(BitMap bits);
 253 
 254   // Requires the submap of "bits" starting at offset to be at least as
 255   // large as "this".  Modifies "this" to be the intersection of its
 256   // current contents and the submap of "bits" starting at "offset" of the
 257   // same length as "this."
 258   // (For expedience, currently requires the offset to be aligned to the
 259   // bitsize of a uintptr_t.  This should go away in the future though it
 260   // will probably remain a good case to optimize.)
 261   void set_intersection_at_offset(BitMap bits, idx_t offset);
 262 
 263   void set_from(BitMap bits);
 264 
 265   bool is_same(BitMap bits);
 266 
 267   // Test if all bits are set or cleared
 268   bool is_full() const;
 269   bool is_empty() const;
 270 
 271   void print_on_error(outputStream* st, const char* prefix) const;
 272 
 273 #ifndef PRODUCT
 274  public:
 275   // Printing
 276   void print_on(outputStream* st) const;
 277 #endif
 278 };
 279 
 280 class BitMapIterator VALUE_OBJ_CLASS_SPEC {
 281   friend class BitMap;
 282 
 283   typedef BitMap::idx_t idx_t;          // Type used for bit and word indices.
 284   typedef BitMap::bm_word_t bm_word_t;  // Element type of array that
 285                                         // represents the bitmap.
 286 
 287   // We walk over the bits in a word in chunks of size window_size.
 288   enum { window_size = 8,
 289          window_mask = right_n_bits(window_size),
 290          table_size  = (1 << window_size) };
 291 
 292   // For an integer of length window_size, what is the first set bit?
 293   static const uint8_t _first_bit[table_size];
 294 
 295   // For an integer of length window_size, what is the first set bit?
 296   static const uint8_t _second_bit[table_size];
 297 
 298   BitMap* _bs;
 299   bm_word_t _current;
 300   idx_t   _value;
 301   idx_t   _last_word;
 302   idx_t   _max_word;
 303 
 304  public:
 305   BitMapIterator(BitMap* bs);
 306 
 307   // Return the next element of the set.  Return 0 when done.
 308 
 309   idx_t next();
 310 };
 311 
 312 // Convenience class wrapping BitMap which provides multiple bits per slot.
 313 class BitMap2D VALUE_OBJ_CLASS_SPEC {
 314  public:
 315   typedef BitMap::idx_t idx_t;          // Type used for bit and word indices.
 316   typedef BitMap::bm_word_t bm_word_t;  // Element type of array that
 317                                         // represents the bitmap.
 318  private:
 319   BitMap _map;
 320   idx_t  _bits_per_slot;
 321 
 322   idx_t bit_index(idx_t slot_index, idx_t bit_within_slot_index) const {
 323     return slot_index * _bits_per_slot + bit_within_slot_index;
 324   }
 325 
 326   void verify_bit_within_slot_index(idx_t index) const {
 327     assert(index < _bits_per_slot, "bit_within_slot index out of bounds");
 328   }
 329 
 330  public:
 331   // Construction. bits_per_slot must be greater than 0.
 332   BitMap2D(bm_word_t* map, idx_t size_in_slots, idx_t bits_per_slot);
 333 
 334   // Allocates necessary data structure in resource area. bits_per_slot must be greater than 0.
 335   BitMap2D(idx_t size_in_slots, idx_t bits_per_slot);
 336 
 337   idx_t size_in_bits() {
 338     return _map.size();
 339   }
 340 
 341   // Returns number of full slots that have been allocated
 342   idx_t size_in_slots() {
 343     // Round down
 344     return _map.size() / _bits_per_slot;
 345   }
 346 
 347   bool is_valid_index(idx_t slot_index, idx_t bit_within_slot_index) {
 348     verify_bit_within_slot_index(bit_within_slot_index);
 349     return (bit_index(slot_index, bit_within_slot_index) < size_in_bits());
 350   }
 351 
 352   bool at(idx_t slot_index, idx_t bit_within_slot_index) const {
 353     verify_bit_within_slot_index(bit_within_slot_index);
 354     return _map.at(bit_index(slot_index, bit_within_slot_index));
 355   }
 356 
 357   void set_bit(idx_t slot_index, idx_t bit_within_slot_index) {
 358     verify_bit_within_slot_index(bit_within_slot_index);
 359     _map.set_bit(bit_index(slot_index, bit_within_slot_index));
 360   }
 361 
 362   void clear_bit(idx_t slot_index, idx_t bit_within_slot_index) {
 363     verify_bit_within_slot_index(bit_within_slot_index);
 364     _map.clear_bit(bit_index(slot_index, bit_within_slot_index));
 365   }
 366 
 367   void at_put(idx_t slot_index, idx_t bit_within_slot_index, bool value) {
 368     verify_bit_within_slot_index(bit_within_slot_index);
 369     _map.at_put(bit_index(slot_index, bit_within_slot_index), value);
 370   }
 371 
 372   void at_put_grow(idx_t slot_index, idx_t bit_within_slot_index, bool value) {
 373     verify_bit_within_slot_index(bit_within_slot_index);
 374     _map.at_put_grow(bit_index(slot_index, bit_within_slot_index), value);
 375   }
 376 
 377   void clear();
 378 };
 379 
 380 // Closure for iterating over BitMaps
 381 
 382 class BitMapClosure VALUE_OBJ_CLASS_SPEC {
 383  public:
 384   // Callback when bit in map is set.  Should normally return "true";
 385   // return of false indicates that the bitmap iteration should terminate.
 386   virtual bool do_bit(BitMap::idx_t offset) = 0;
 387 };
 388 
 389 #endif // SHARE_VM_UTILITIES_BITMAP_HPP