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