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 31 // Forward decl; 32 class BitMapClosure; 33 34 // Operations for bitmaps represented as arrays of unsigned integers. 35 // Bits 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 the 53 // bitmap, with BitsPerWord bits per element. 54 // If this were to fail, there are lots of places that would need repair. 55 STATIC_ASSERT((sizeof(bm_word_t) * BitsPerByte) == BitsPerWord); 56 57 // Hints for range sizes. 58 typedef enum { 59 unknown_range, small_range, large_range 60 } RangeSizeHint; 61 62 private: 63 bm_word_t* _map; // First word in bitmap 64 idx_t _size; // Size of bitmap (in bits) 65 66 // The maximum allowable size of a bitmap, in words or bits. 67 // Limit max_size_in_bits so aligning up to a word boundary never overflows. 68 static idx_t max_size_in_words() { return raw_to_words_align_down(~idx_t(0)); } 69 static idx_t max_size_in_bits() { return max_size_in_words() * BitsPerWord; } 70 71 // Assumes relevant validity checking for bit has already been done. 72 static idx_t raw_to_words_align_up(idx_t bit) { 73 return raw_to_words_align_down(bit + (BitsPerWord - 1)); 74 } 75 76 // Assumes relevant validity checking for bit has already been done. 77 static idx_t raw_to_words_align_down(idx_t bit) { 78 return bit >> LogBitsPerWord; 79 } 80 81 // Word-aligns bit and converts it to a word offset. 82 // precondition: bit <= size() 83 idx_t to_words_align_up(idx_t bit) const { 84 verify_limit(bit); 85 return raw_to_words_align_up(bit); 86 } 87 88 // Word-aligns bit and converts it to a word offset. 89 // precondition: bit <= size() 90 inline idx_t to_words_align_down(idx_t bit) const { 91 verify_limit(bit); 92 return raw_to_words_align_down(bit); 93 } 94 95 // Helper for get_next_{zero,one}_bit variants. 96 // - flip designates whether searching for 1s or 0s. Must be one of 97 // find_{zeros,ones}_flip. 98 // - aligned_right is true if r_index is a priori on a bm_word_t boundary. 99 template<bm_word_t flip, bool aligned_right> 100 inline idx_t get_next_bit_impl(idx_t l_index, idx_t r_index) const; 101 102 // Values for get_next_bit_impl flip parameter. 103 static const bm_word_t find_ones_flip = 0; 104 static const bm_word_t find_zeros_flip = ~(bm_word_t)0; 105 106 // Threshold for performing small range operation, even when large range 107 // operation was requested. Measured in words. 108 static const size_t small_range_words = 32; 109 110 static bool is_small_range_of_words(idx_t beg_full_word, idx_t end_full_word); 111 112 protected: 113 // Return the position of bit within the word that contains it (e.g., if 114 // bitmap words are 32 bits, return a number 0 <= n <= 31). 115 static idx_t bit_in_word(idx_t bit) { return bit & (BitsPerWord - 1); } 116 117 // Return a mask that will select the specified bit, when applied to the word 118 // containing the bit. 119 static bm_word_t bit_mask(idx_t bit) { return (bm_word_t)1 << bit_in_word(bit); } 120 121 // Return the bit number of the first bit in the specified word. 122 static idx_t bit_index(idx_t word) { return word << LogBitsPerWord; } 123 124 // Return the array of bitmap words, or a specific word from it. 125 bm_word_t* map() { return _map; } 126 const bm_word_t* map() const { return _map; } 127 bm_word_t map(idx_t word) const { return _map[word]; } 128 129 // Return a pointer to the word containing the specified bit. 130 bm_word_t* word_addr(idx_t bit) { 131 return map() + to_words_align_down(bit); 132 } 133 const bm_word_t* word_addr(idx_t bit) const { 134 return map() + to_words_align_down(bit); 135 } 136 137 // Set a word to a specified value or to all ones; clear a word. 138 void set_word (idx_t word, bm_word_t val) { _map[word] = val; } 139 void set_word (idx_t word) { set_word(word, ~(bm_word_t)0); } 140 void clear_word(idx_t word) { _map[word] = 0; } 141 142 static inline const bm_word_t load_word_ordered(const volatile bm_word_t* const addr, atomic_memory_order memory_order); 143 144 // Utilities for ranges of bits. Ranges are half-open [beg, end). 145 146 // Ranges within a single word. 147 bm_word_t inverted_bit_mask_for_range(idx_t beg, idx_t end) const; 148 void set_range_within_word (idx_t beg, idx_t end); 149 void clear_range_within_word (idx_t beg, idx_t end); 150 void par_put_range_within_word (idx_t beg, idx_t end, bool value); 151 152 // Ranges spanning entire words. 153 void set_range_of_words (idx_t beg, idx_t end); 154 void clear_range_of_words (idx_t beg, idx_t end); 155 void set_large_range_of_words (idx_t beg, idx_t end); 156 void clear_large_range_of_words (idx_t beg, idx_t end); 157 158 static void clear_range_of_words(bm_word_t* map, idx_t beg, idx_t end); 159 160 // Verification. 161 162 // Verify size_in_bits does not exceed max_size_in_bits(). 163 static void verify_size(idx_t size_in_bits) NOT_DEBUG_RETURN; 164 // Verify bit is less than size(). 165 void verify_index(idx_t bit) const NOT_DEBUG_RETURN; 166 // Verify bit is not greater than size(). 167 void verify_limit(idx_t bit) const NOT_DEBUG_RETURN; 168 // Verify [beg,end) is a valid range, e.g. beg <= end <= size(). 169 void verify_range(idx_t beg, idx_t end) const NOT_DEBUG_RETURN; 170 171 // Statistics. 172 static const idx_t* _pop_count_table; 173 static void init_pop_count_table(); 174 static idx_t num_set_bits(bm_word_t w); 175 static idx_t num_set_bits_from_table(unsigned char c); 176 177 // Allocation Helpers. 178 179 // Allocates and clears the bitmap memory. 180 template <class Allocator> 181 static bm_word_t* allocate(const Allocator&, idx_t size_in_bits, bool clear = true); 182 183 // Reallocates and clears the new bitmap memory. 184 template <class Allocator> 185 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); 186 187 // Free the bitmap memory. 188 template <class Allocator> 189 static void free(const Allocator&, bm_word_t* map, idx_t size_in_bits); 190 191 // Protected functions, that are used by BitMap sub-classes that support them. 192 193 // Resize the backing bitmap memory. 194 // 195 // Old bits are transfered to the new memory 196 // and the extended memory is cleared. 197 template <class Allocator> 198 void resize(const Allocator& allocator, idx_t new_size_in_bits, bool clear); 199 200 // Set up and clear the bitmap memory. 201 // 202 // Precondition: The bitmap was default constructed and has 203 // not yet had memory allocated via resize or (re)initialize. 204 template <class Allocator> 205 void initialize(const Allocator& allocator, idx_t size_in_bits, bool clear); 206 207 // Set up and clear the bitmap memory. 208 // 209 // Can be called on previously initialized bitmaps. 210 template <class Allocator> 211 void reinitialize(const Allocator& allocator, idx_t new_size_in_bits, bool clear); 212 213 // Set the map and size. 214 void update(bm_word_t* map, idx_t size) { 215 _map = map; 216 _size = size; 217 } 218 219 // Protected constructor and destructor. 220 BitMap(bm_word_t* map, idx_t size_in_bits) : _map(map), _size(size_in_bits) { 221 verify_size(size_in_bits); 222 } 223 ~BitMap() {} 224 225 public: 226 // Pretouch the entire range of memory this BitMap covers. 227 void pretouch(); 228 229 // Accessing 230 static idx_t calc_size_in_words(size_t size_in_bits) { 231 verify_size(size_in_bits); 232 return raw_to_words_align_up(size_in_bits); 233 } 234 235 idx_t size() const { return _size; } 236 idx_t size_in_words() const { return calc_size_in_words(size()); } 237 idx_t size_in_bytes() const { return size_in_words() * BytesPerWord; } 238 239 bool at(idx_t index) const { 240 verify_index(index); 241 return (*word_addr(index) & bit_mask(index)) != 0; 242 } 243 244 // memory_order must be memory_order_relaxed or memory_order_acquire. 245 bool par_at(idx_t index, atomic_memory_order memory_order = memory_order_acquire) const; 246 247 // Set or clear the specified bit. 248 inline void set_bit(idx_t bit); 249 inline void clear_bit(idx_t bit); 250 251 // Attempts to change a bit to a desired value. The operation returns true if 252 // this thread changed the value of the bit. It was changed with a RMW operation 253 // using the specified memory_order. The operation returns false if the change 254 // could not be set due to the bit already being observed in the desired state. 255 // The atomic access that observed the bit in the desired state has acquire 256 // semantics, unless memory_order is memory_order_relaxed or memory_order_release. 257 inline bool par_set_bit(idx_t bit, atomic_memory_order memory_order = memory_order_conservative); 258 inline bool par_clear_bit(idx_t bit, atomic_memory_order memory_order = memory_order_conservative); 259 260 // Put the given value at the given index. The parallel version 261 // will CAS the value into the bitmap and is quite a bit slower. 262 // The parallel version also returns a value indicating if the 263 // calling thread was the one that changed the value of the bit. 264 void at_put(idx_t index, bool value); 265 bool par_at_put(idx_t index, bool value); 266 267 // Update a range of bits. Ranges are half-open [beg, end). 268 void set_range (idx_t beg, idx_t end); 269 void clear_range (idx_t beg, idx_t end); 270 void set_large_range (idx_t beg, idx_t end); 271 void clear_large_range (idx_t beg, idx_t end); 272 void at_put_range(idx_t beg, idx_t end, bool value); 273 void par_at_put_range(idx_t beg, idx_t end, bool value); 274 void at_put_large_range(idx_t beg, idx_t end, bool value); 275 void par_at_put_large_range(idx_t beg, idx_t end, bool value); 276 277 // Update a range of bits, using a hint about the size. Currently only 278 // inlines the predominant case of a 1-bit range. Works best when hint is a 279 // compile-time constant. 280 void set_range(idx_t beg, idx_t end, RangeSizeHint hint); 281 void clear_range(idx_t beg, idx_t end, RangeSizeHint hint); 282 void par_set_range(idx_t beg, idx_t end, RangeSizeHint hint); 283 void par_clear_range (idx_t beg, idx_t end, RangeSizeHint hint); 284 285 // Clearing 286 void clear_large(); 287 inline void clear(); 288 289 // Iteration support. Returns "true" if the iteration completed, false 290 // if the iteration terminated early (because the closure "blk" returned 291 // false). 292 bool iterate(BitMapClosure* blk, idx_t leftIndex, idx_t rightIndex); 293 bool iterate(BitMapClosure* blk) { 294 // call the version that takes an interval 295 return iterate(blk, 0, size()); 296 } 297 298 // Looking for 1's and 0's at indices equal to or greater than "l_index", 299 // stopping if none has been found before "r_index", and returning 300 // "r_index" (which must be at most "size") in that case. 301 idx_t get_next_one_offset (idx_t l_index, idx_t r_index) const; 302 idx_t get_next_zero_offset(idx_t l_index, idx_t r_index) const; 303 304 idx_t get_next_one_offset(idx_t offset) const { 305 return get_next_one_offset(offset, size()); 306 } 307 idx_t get_next_zero_offset(idx_t offset) const { 308 return get_next_zero_offset(offset, size()); 309 } 310 311 // Like "get_next_one_offset", except requires that "r_index" is 312 // aligned to bitsizeof(bm_word_t). 313 idx_t get_next_one_offset_aligned_right(idx_t l_index, idx_t r_index) const; 314 315 // Returns the number of bits set in the bitmap. 316 idx_t count_one_bits() const; 317 318 // Set operations. 319 void set_union(const BitMap& bits); 320 void set_difference(const BitMap& bits); 321 void set_intersection(const BitMap& bits); 322 // Returns true iff "this" is a superset of "bits". 323 bool contains(const BitMap& bits) const; 324 // Returns true iff "this and "bits" have a non-empty intersection. 325 bool intersects(const BitMap& bits) const; 326 327 // Returns result of whether this map changed 328 // during the operation 329 bool set_union_with_result(const BitMap& bits); 330 bool set_difference_with_result(const BitMap& bits); 331 bool set_intersection_with_result(const BitMap& bits); 332 333 void set_from(const BitMap& bits); 334 335 bool is_same(const BitMap& bits) const; 336 337 // Test if all bits are set or cleared 338 bool is_full() const; 339 bool is_empty() const; 340 341 void write_to(bm_word_t* buffer, size_t buffer_size_in_bytes) const; 342 void print_on_error(outputStream* st, const char* prefix) const; 343 344 #ifndef PRODUCT 345 public: 346 // Printing 347 void print_on(outputStream* st) const; 348 #endif 349 }; 350 351 // A concrete implementation of the the "abstract" BitMap class. 352 // 353 // The BitMapView is used when the backing storage is managed externally. 354 class BitMapView : public BitMap { 355 public: 356 BitMapView() : BitMap(NULL, 0) {} 357 BitMapView(bm_word_t* map, idx_t size_in_bits) : BitMap(map, size_in_bits) {} 358 }; 359 360 // A BitMap with storage in a ResourceArea. 361 class ResourceBitMap : public BitMap { 362 363 public: 364 ResourceBitMap() : BitMap(NULL, 0) {} 365 // Conditionally clears the bitmap memory. 366 ResourceBitMap(idx_t size_in_bits, bool clear = true); 367 368 // Resize the backing bitmap memory. 369 // 370 // Old bits are transfered to the new memory 371 // and the extended memory is cleared. 372 void resize(idx_t new_size_in_bits); 373 374 // Set up and clear the bitmap memory. 375 // 376 // Precondition: The bitmap was default constructed and has 377 // not yet had memory allocated via resize or initialize. 378 void initialize(idx_t size_in_bits); 379 380 // Set up and clear the bitmap memory. 381 // 382 // Can be called on previously initialized bitmaps. 383 void reinitialize(idx_t size_in_bits); 384 }; 385 386 // A BitMap with storage in a specific Arena. 387 class ArenaBitMap : public BitMap { 388 public: 389 // Clears the bitmap memory. 390 ArenaBitMap(Arena* arena, idx_t size_in_bits); 391 392 private: 393 // Don't allow copy or assignment. 394 ArenaBitMap(const ArenaBitMap&); 395 ArenaBitMap& operator=(const ArenaBitMap&); 396 }; 397 398 // A BitMap with storage in the CHeap. 399 class CHeapBitMap : public BitMap { 400 401 private: 402 // Don't allow copy or assignment, to prevent the 403 // allocated memory from leaking out to other instances. 404 CHeapBitMap(const CHeapBitMap&); 405 CHeapBitMap& operator=(const CHeapBitMap&); 406 407 // NMT memory type 408 MEMFLAGS _flags; 409 410 public: 411 CHeapBitMap(MEMFLAGS flags = mtInternal) : BitMap(NULL, 0), _flags(flags) {} 412 // Clears the bitmap memory. 413 CHeapBitMap(idx_t size_in_bits, MEMFLAGS flags = mtInternal, bool clear = true); 414 ~CHeapBitMap(); 415 416 // Resize the backing bitmap memory. 417 // 418 // Old bits are transfered to the new memory 419 // and the extended memory is (optionally) cleared. 420 void resize(idx_t new_size_in_bits, bool clear = true); 421 422 // Set up and (optionally) clear the bitmap memory. 423 // 424 // Precondition: The bitmap was default constructed and has 425 // not yet had memory allocated via resize or initialize. 426 void initialize(idx_t size_in_bits, bool clear = true); 427 428 // Set up and (optionally) clear the bitmap memory. 429 // 430 // Can be called on previously initialized bitmaps. 431 void reinitialize(idx_t size_in_bits, bool clear = true); 432 }; 433 434 // Convenience class wrapping BitMap which provides multiple bits per slot. 435 class BitMap2D { 436 public: 437 typedef BitMap::idx_t idx_t; // Type used for bit and word indices. 438 typedef BitMap::bm_word_t bm_word_t; // Element type of array that 439 // represents the bitmap. 440 private: 441 ResourceBitMap _map; 442 idx_t _bits_per_slot; 443 444 idx_t bit_index(idx_t slot_index, idx_t bit_within_slot_index) const { 445 return slot_index * _bits_per_slot + bit_within_slot_index; 446 } 447 448 void verify_bit_within_slot_index(idx_t index) const { 449 assert(index < _bits_per_slot, "bit_within_slot index out of bounds"); 450 } 451 452 public: 453 // Construction. bits_per_slot must be greater than 0. 454 BitMap2D(idx_t bits_per_slot) : 455 _map(), _bits_per_slot(bits_per_slot) {} 456 457 // Allocates necessary data structure in resource area. bits_per_slot must be greater than 0. 458 BitMap2D(idx_t size_in_slots, idx_t bits_per_slot) : 459 _map(size_in_slots * bits_per_slot), _bits_per_slot(bits_per_slot) {} 460 461 idx_t size_in_bits() { 462 return _map.size(); 463 } 464 465 bool is_valid_index(idx_t slot_index, idx_t bit_within_slot_index); 466 bool at(idx_t slot_index, idx_t bit_within_slot_index) const; 467 void set_bit(idx_t slot_index, idx_t bit_within_slot_index); 468 void clear_bit(idx_t slot_index, idx_t bit_within_slot_index); 469 void at_put(idx_t slot_index, idx_t bit_within_slot_index, bool value); 470 void at_put_grow(idx_t slot_index, idx_t bit_within_slot_index, bool value); 471 }; 472 473 // Closure for iterating over BitMaps 474 475 class BitMapClosure { 476 public: 477 // Callback when bit in map is set. Should normally return "true"; 478 // return of false indicates that the bitmap iteration should terminate. 479 virtual bool do_bit(BitMap::idx_t index) = 0; 480 }; 481 482 #endif // SHARE_UTILITIES_BITMAP_HPP