1 /* 2 * Copyright (c) 1997, 2019, 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. 8 * 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 16 * 2 along with this work; if not, write to the Free Software Foundation, 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 21 * questions. 22 * 23 */ 24 25 #ifndef SHARE_UTILITIES_BITMAP_HPP 26 #define SHARE_UTILITIES_BITMAP_HPP 27 28 #include "memory/allocation.hpp" 29 #include "runtime/atomic.hpp" 30 #include "utilities/align.hpp" 31 32 // Forward decl; 33 class BitMapClosure; 34 35 // Operations for bitmaps represented as arrays of unsigned integers. 36 // Bit offsets are numbered from 0 to size-1. 37 38 // The "abstract" base BitMap class. 39 // 40 // The constructor and destructor are protected to prevent 41 // creation of BitMap instances outside of the BitMap class. 42 // 43 // The BitMap class doesn't use virtual calls on purpose, 44 // this ensures that we don't get a vtable unnecessarily. 45 // 46 // The allocation of the backing storage for the BitMap are handled by 47 // the subclasses. BitMap doesn't allocate or delete backing storage. 48 class BitMap { 49 friend class BitMap2D; 50 51 public: 52 typedef size_t idx_t; // Type used for bit and word indices. 53 typedef uintptr_t bm_word_t; // Element type of array that represents 54 // the bitmap. 55 56 // Hints for range sizes. 57 typedef enum { 58 unknown_range, small_range, large_range 59 } RangeSizeHint; 60 61 private: 62 bm_word_t* _map; // First word in bitmap 63 idx_t _size; // Size of bitmap (in bits) 64 65 // Helper for get_next_{zero,one}_bit variants. 66 // - flip designates whether searching for 1s or 0s. Must be one of 67 // find_{zeros,ones}_flip. 68 // - aligned_right is true if r_index is a priori on a bm_word_t boundary. 69 template<bm_word_t flip, bool aligned_right> 70 inline idx_t get_next_bit_impl(idx_t l_index, idx_t r_index) const; 71 72 // Values for get_next_bit_impl flip parameter. 73 static const bm_word_t find_ones_flip = 0; 74 static const bm_word_t find_zeros_flip = ~(bm_word_t)0; 75 76 // Threshold for performing small range operation, even when large range 77 // operation was requested. Measured in words. 78 static const size_t small_range_words = 32; 79 80 protected: 81 // Return the position of bit within the word that contains it (e.g., if 82 // bitmap words are 32 bits, return a number 0 <= n <= 31). 83 static idx_t bit_in_word(idx_t bit) { return bit & (BitsPerWord - 1); } 84 85 // Return a mask that will select the specified bit, when applied to the word 86 // containing the bit. 87 static bm_word_t bit_mask(idx_t bit) { return (bm_word_t)1 << bit_in_word(bit); } 88 89 // Return the index of the word containing the specified bit. 90 static idx_t word_index(idx_t bit) { return bit >> LogBitsPerWord; } 91 92 // Return the bit number of the first bit in the specified word. 93 static idx_t bit_index(idx_t word) { return word << LogBitsPerWord; } 94 95 // Return the array of bitmap words, or a specific word from it. 96 bm_word_t* map() { return _map; } 97 const bm_word_t* map() const { return _map; } 98 bm_word_t map(idx_t word) const { return _map[word]; } 99 100 // Return a pointer to the word containing the specified bit. 101 bm_word_t* word_addr(idx_t bit) { return map() + word_index(bit); } 102 const bm_word_t* word_addr(idx_t bit) const { return map() + word_index(bit); } 103 104 // Set a word to a specified value or to all ones; clear a word. 105 void set_word (idx_t word, bm_word_t val) { _map[word] = val; } 106 void set_word (idx_t word) { set_word(word, ~(bm_word_t)0); } 107 void clear_word(idx_t word) { _map[word] = 0; } 108 109 static inline const bm_word_t load_word_ordered(const volatile bm_word_t* const addr, atomic_memory_order memory_order); 110 111 // Utilities for ranges of bits. Ranges are half-open [beg, end). 112 113 // Ranges within a single word. 114 bm_word_t inverted_bit_mask_for_range(idx_t beg, idx_t end) const; 115 void set_range_within_word (idx_t beg, idx_t end); 116 void clear_range_within_word (idx_t beg, idx_t end); 117 void par_put_range_within_word (idx_t beg, idx_t end, bool value); 118 119 // Ranges spanning entire words. 120 void set_range_of_words (idx_t beg, idx_t end); 121 void clear_range_of_words (idx_t beg, idx_t end); 122 void set_large_range_of_words (idx_t beg, idx_t end); 123 void clear_large_range_of_words (idx_t beg, idx_t end); 124 125 static void clear_range_of_words(bm_word_t* map, idx_t beg, idx_t end); 126 127 static bool is_small_range_of_words(idx_t beg_full_word, idx_t end_full_word); 128 129 // The index of the first full word in a range. 130 idx_t word_index_round_up(idx_t bit) const; 131 132 // Verification. 133 void verify_index(idx_t index) const NOT_DEBUG_RETURN; 134 void verify_range(idx_t beg_index, idx_t end_index) const NOT_DEBUG_RETURN; 135 136 // Statistics. 137 static const idx_t* _pop_count_table; 138 static void init_pop_count_table(); 139 static idx_t num_set_bits(bm_word_t w); 140 static idx_t num_set_bits_from_table(unsigned char c); 141 142 // Allocation Helpers. 143 144 // Allocates and clears the bitmap memory. 145 template <class Allocator> 146 static bm_word_t* allocate(const Allocator&, idx_t size_in_bits, bool clear = true); 147 148 // Reallocates and clears the new bitmap memory. 149 template <class Allocator> 150 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); 151 152 // Free the bitmap memory. 153 template <class Allocator> 154 static void free(const Allocator&, bm_word_t* map, idx_t size_in_bits); 155 156 // Protected functions, that are used by BitMap sub-classes that support them. 157 158 // Resize the backing bitmap memory. 159 // 160 // Old bits are transfered to the new memory 161 // and the extended memory is cleared. 162 template <class Allocator> 163 void resize(const Allocator& allocator, idx_t new_size_in_bits, bool clear); 164 165 // Set up and clear the bitmap memory. 166 // 167 // Precondition: The bitmap was default constructed and has 168 // not yet had memory allocated via resize or (re)initialize. 169 template <class Allocator> 170 void initialize(const Allocator& allocator, idx_t size_in_bits, bool clear); 171 172 // Set up and clear the bitmap memory. 173 // 174 // Can be called on previously initialized bitmaps. 175 template <class Allocator> 176 void reinitialize(const Allocator& allocator, idx_t new_size_in_bits, bool clear); 177 178 // Set the map and size. 179 void update(bm_word_t* map, idx_t size) { 180 _map = map; 181 _size = size; 182 } 183 184 // Protected constructor and destructor. 185 BitMap(bm_word_t* map, idx_t size_in_bits) : _map(map), _size(size_in_bits) {} 186 ~BitMap() {} 187 188 public: 189 // Pretouch the entire range of memory this BitMap covers. 190 void pretouch(); 191 192 // Accessing 193 static idx_t calc_size_in_words(size_t size_in_bits) { 194 return word_index(size_in_bits + BitsPerWord - 1); 195 } 196 197 static idx_t calc_size_in_bytes(size_t size_in_bits) { 198 return calc_size_in_words(size_in_bits) * BytesPerWord; 199 } 200 201 idx_t size() const { return _size; } 202 idx_t size_in_words() const { return calc_size_in_words(size()); } 203 idx_t size_in_bytes() const { return calc_size_in_bytes(size()); } 204 205 bool at(idx_t index) const { 206 verify_index(index); 207 return (*word_addr(index) & bit_mask(index)) != 0; 208 } 209 210 // memory_order must be memory_order_relaxed or memory_order_acquire. 211 bool par_at(idx_t index, atomic_memory_order memory_order = memory_order_acquire) const; 212 213 // Align bit index up or down to the next bitmap word boundary, or check 214 // alignment. 215 static idx_t word_align_up(idx_t bit) { 216 return align_up(bit, BitsPerWord); 217 } 218 static idx_t word_align_down(idx_t bit) { 219 return align_down(bit, BitsPerWord); 220 } 221 static bool is_word_aligned(idx_t bit) { 222 return word_align_up(bit) == bit; 223 } 224 225 // Set or clear the specified bit. 226 inline void set_bit(idx_t bit); 227 inline void clear_bit(idx_t bit); 228 229 // Attempts to change a bit to a desired value. The operation returns true if 230 // this thread changed the value of the bit. It was changed with a RMW operation 231 // using the specified memory_order. The operation returns false if the change 232 // could not be set due to the bit already being observed in the desired state. 233 // The atomic access that observed the bit in the desired state has acquire 234 // semantics, unless memory_order is memory_order_relaxed or memory_order_release. 235 inline bool par_set_bit(idx_t bit, atomic_memory_order memory_order = memory_order_conservative); 236 inline bool par_clear_bit(idx_t bit, atomic_memory_order memory_order = memory_order_conservative); 237 238 // Put the given value at the given offset. The parallel version 239 // will CAS the value into the bitmap and is quite a bit slower. 240 // The parallel version also returns a value indicating if the 241 // calling thread was the one that changed the value of the bit. 242 void at_put(idx_t index, bool value); 243 bool par_at_put(idx_t index, bool value); 244 245 // Update a range of bits. Ranges are half-open [beg, end). 246 void set_range (idx_t beg, idx_t end); 247 void clear_range (idx_t beg, idx_t end); 248 void set_large_range (idx_t beg, idx_t end); 249 void clear_large_range (idx_t beg, idx_t end); 250 void at_put_range(idx_t beg, idx_t end, bool value); 251 void par_at_put_range(idx_t beg, idx_t end, bool value); 252 void at_put_large_range(idx_t beg, idx_t end, bool value); 253 void par_at_put_large_range(idx_t beg, idx_t end, bool value); 254 255 // Update a range of bits, using a hint about the size. Currently only 256 // inlines the predominant case of a 1-bit range. Works best when hint is a 257 // compile-time constant. 258 void set_range(idx_t beg, idx_t end, RangeSizeHint hint); 259 void clear_range(idx_t beg, idx_t end, RangeSizeHint hint); 260 void par_set_range(idx_t beg, idx_t end, RangeSizeHint hint); 261 void par_clear_range (idx_t beg, idx_t end, RangeSizeHint hint); 262 263 // Clearing 264 void clear_large(); 265 inline void clear(); 266 267 // Iteration support. Returns "true" if the iteration completed, false 268 // if the iteration terminated early (because the closure "blk" returned 269 // false). 270 bool iterate(BitMapClosure* blk, idx_t leftIndex, idx_t rightIndex); 271 bool iterate(BitMapClosure* blk) { 272 // call the version that takes an interval 273 return iterate(blk, 0, size()); 274 } 275 276 // Looking for 1's and 0's at indices equal to or greater than "l_index", 277 // stopping if none has been found before "r_index", and returning 278 // "r_index" (which must be at most "size") in that case. 279 idx_t get_next_one_offset (idx_t l_index, idx_t r_index) const; 280 idx_t get_next_zero_offset(idx_t l_index, idx_t r_index) const; 281 282 idx_t get_next_one_offset(idx_t offset) const { 283 return get_next_one_offset(offset, size()); 284 } 285 idx_t get_next_zero_offset(idx_t offset) const { 286 return get_next_zero_offset(offset, size()); 287 } 288 289 // Like "get_next_one_offset", except requires that "r_index" is 290 // aligned to bitsizeof(bm_word_t). 291 idx_t get_next_one_offset_aligned_right(idx_t l_index, idx_t r_index) const; 292 293 // Returns the number of bits set in the bitmap. 294 idx_t count_one_bits() const; 295 296 // Set operations. 297 void set_union(const BitMap& bits); 298 void set_difference(const BitMap& bits); 299 void set_intersection(const BitMap& bits); 300 // Returns true iff "this" is a superset of "bits". 301 bool contains(const BitMap& bits) const; 302 // Returns true iff "this and "bits" have a non-empty intersection. 303 bool intersects(const BitMap& bits) const; 304 305 // Returns result of whether this map changed 306 // during the operation 307 bool set_union_with_result(const BitMap& bits); 308 bool set_difference_with_result(const BitMap& bits); 309 bool set_intersection_with_result(const BitMap& bits); 310 311 void set_from(const BitMap& bits); 312 313 bool is_same(const BitMap& bits) const; 314 315 // Test if all bits are set or cleared 316 bool is_full() const; 317 bool is_empty() const; 318 319 void write_to(bm_word_t* buffer, size_t buffer_size_in_bytes) const; 320 void print_on_error(outputStream* st, const char* prefix) const; 321 322 #ifndef PRODUCT 323 public: 324 // Printing 325 void print_on(outputStream* st) const; 326 #endif 327 }; 328 329 // A concrete implementation of the the "abstract" BitMap class. 330 // 331 // The BitMapView is used when the backing storage is managed externally. 332 class BitMapView : public BitMap { 333 public: 334 BitMapView() : BitMap(NULL, 0) {} 335 BitMapView(bm_word_t* map, idx_t size_in_bits) : BitMap(map, size_in_bits) {} 336 }; 337 338 // A BitMap with storage in a ResourceArea. 339 class ResourceBitMap : public BitMap { 340 341 public: 342 ResourceBitMap() : BitMap(NULL, 0) {} 343 // Conditionally clears the bitmap memory. 344 ResourceBitMap(idx_t size_in_bits, bool clear = true); 345 346 // Resize the backing bitmap memory. 347 // 348 // Old bits are transfered to the new memory 349 // and the extended memory is cleared. 350 void resize(idx_t new_size_in_bits); 351 352 // Set up and clear the bitmap memory. 353 // 354 // Precondition: The bitmap was default constructed and has 355 // not yet had memory allocated via resize or initialize. 356 void initialize(idx_t size_in_bits); 357 358 // Set up and clear the bitmap memory. 359 // 360 // Can be called on previously initialized bitmaps. 361 void reinitialize(idx_t size_in_bits); 362 }; 363 364 // A BitMap with storage in a specific Arena. 365 class ArenaBitMap : public BitMap { 366 public: 367 // Clears the bitmap memory. 368 ArenaBitMap(Arena* arena, idx_t size_in_bits); 369 370 private: 371 // Don't allow copy or assignment. 372 ArenaBitMap(const ArenaBitMap&); 373 ArenaBitMap& operator=(const ArenaBitMap&); 374 }; 375 376 // A BitMap with storage in the CHeap. 377 class CHeapBitMap : public BitMap { 378 379 private: 380 // Don't allow copy or assignment, to prevent the 381 // allocated memory from leaking out to other instances. 382 CHeapBitMap(const CHeapBitMap&); 383 CHeapBitMap& operator=(const CHeapBitMap&); 384 385 // NMT memory type 386 MEMFLAGS _flags; 387 388 public: 389 CHeapBitMap(MEMFLAGS flags = mtInternal) : BitMap(NULL, 0), _flags(flags) {} 390 // Clears the bitmap memory. 391 CHeapBitMap(idx_t size_in_bits, MEMFLAGS flags = mtInternal, bool clear = true); 392 ~CHeapBitMap(); 393 394 // Resize the backing bitmap memory. 395 // 396 // Old bits are transfered to the new memory 397 // and the extended memory is (optionally) cleared. 398 void resize(idx_t new_size_in_bits, bool clear = true); 399 400 // Set up and (optionally) clear the bitmap memory. 401 // 402 // Precondition: The bitmap was default constructed and has 403 // not yet had memory allocated via resize or initialize. 404 void initialize(idx_t size_in_bits, bool clear = true); 405 406 // Set up and (optionally) clear the bitmap memory. 407 // 408 // Can be called on previously initialized bitmaps. 409 void reinitialize(idx_t size_in_bits, bool clear = true); 410 }; 411 412 // Convenience class wrapping BitMap which provides multiple bits per slot. 413 class BitMap2D { 414 public: 415 typedef BitMap::idx_t idx_t; // Type used for bit and word indices. 416 typedef BitMap::bm_word_t bm_word_t; // Element type of array that 417 // represents the bitmap. 418 private: 419 ResourceBitMap _map; 420 idx_t _bits_per_slot; 421 422 idx_t bit_index(idx_t slot_index, idx_t bit_within_slot_index) const { 423 return slot_index * _bits_per_slot + bit_within_slot_index; 424 } 425 426 void verify_bit_within_slot_index(idx_t index) const { 427 assert(index < _bits_per_slot, "bit_within_slot index out of bounds"); 428 } 429 430 public: 431 // Construction. bits_per_slot must be greater than 0. 432 BitMap2D(idx_t bits_per_slot) : 433 _map(), _bits_per_slot(bits_per_slot) {} 434 435 // Allocates necessary data structure in resource area. bits_per_slot must be greater than 0. 436 BitMap2D(idx_t size_in_slots, idx_t bits_per_slot) : 437 _map(size_in_slots * bits_per_slot), _bits_per_slot(bits_per_slot) {} 438 439 idx_t size_in_bits() { 440 return _map.size(); 441 } 442 443 bool is_valid_index(idx_t slot_index, idx_t bit_within_slot_index); 444 bool at(idx_t slot_index, idx_t bit_within_slot_index) const; 445 void set_bit(idx_t slot_index, idx_t bit_within_slot_index); 446 void clear_bit(idx_t slot_index, idx_t bit_within_slot_index); 447 void at_put(idx_t slot_index, idx_t bit_within_slot_index, bool value); 448 void at_put_grow(idx_t slot_index, idx_t bit_within_slot_index, bool value); 449 }; 450 451 // Closure for iterating over BitMaps 452 453 class BitMapClosure { 454 public: 455 // Callback when bit in map is set. Should normally return "true"; 456 // return of false indicates that the bitmap iteration should terminate. 457 virtual bool do_bit(BitMap::idx_t offset) = 0; 458 }; 459 460 #endif // SHARE_UTILITIES_BITMAP_HPP