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