1 /*
2 * Copyright (c) 1997, 2018, 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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7 * published by the Free Software Foundation.
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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).
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23 */
24
25 #ifndef SHARE_VM_UTILITIES_BITMAP_HPP
26 #define SHARE_VM_UTILITIES_BITMAP_HPP
27
28 #include "utilities/align.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
52 // the bitmap.
53
54 // Hints for range sizes.
55 typedef enum {
56 unknown_range, small_range, large_range
57 } RangeSizeHint;
58
59 private:
60 bm_word_t* _map; // First word in bitmap
61 idx_t _size; // Size of bitmap (in bits)
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() { return _map; }
80 const bm_word_t* map() const { return _map; }
81 bm_word_t map(idx_t word) const { return _map[word]; }
82
83 // Return a pointer to the word containing the specified bit.
84 bm_word_t* word_addr(idx_t bit) { return map() + word_index(bit); }
85 const bm_word_t* word_addr(idx_t bit) const { return map() + word_index(bit); }
86
87 // Set a word to a specified value or to all ones; clear a word.
88 void set_word (idx_t word, bm_word_t val) { _map[word] = val; }
89 void set_word (idx_t word) { set_word(word, ~(bm_word_t)0); }
90 void clear_word(idx_t word) { _map[word] = 0; }
91
92 // Utilities for ranges of bits. Ranges are half-open [beg, end).
93
94 // Ranges within a single word.
95 bm_word_t inverted_bit_mask_for_range(idx_t beg, idx_t end) const;
96 void set_range_within_word (idx_t beg, idx_t end);
97 void clear_range_within_word (idx_t beg, idx_t end);
98 void par_put_range_within_word (idx_t beg, idx_t end, bool value);
99
100 // Ranges spanning entire words.
101 void set_range_of_words (idx_t beg, idx_t end);
102 void clear_range_of_words (idx_t beg, idx_t end);
103 void set_large_range_of_words (idx_t beg, idx_t end);
104 void clear_large_range_of_words (idx_t beg, idx_t end);
105
106 static void clear_range_of_words(bm_word_t* map, idx_t beg, idx_t end);
107
108 // The index of the first full word in a range.
109 idx_t word_index_round_up(idx_t bit) const;
110
111 // Verification.
112 void verify_index(idx_t index) const NOT_DEBUG_RETURN;
113 void verify_range(idx_t beg_index, idx_t end_index) const NOT_DEBUG_RETURN;
114
115 // Statistics.
116 static const idx_t* _pop_count_table;
117 static void init_pop_count_table();
118 static idx_t num_set_bits(bm_word_t w);
119 static idx_t num_set_bits_from_table(unsigned char c);
120
121 // Allocation Helpers.
122
123 // Allocates and clears the bitmap memory.
124 template <class Allocator>
125 static bm_word_t* allocate(const Allocator&, idx_t size_in_bits);
126
127 // Reallocates and clears the new bitmap memory.
128 template <class Allocator>
129 static bm_word_t* reallocate(const Allocator&, bm_word_t* map, idx_t old_size_in_bits, idx_t new_size_in_bits);
130
131 // Free the bitmap memory.
132 template <class Allocator>
133 static void free(const Allocator&, bm_word_t* map, idx_t size_in_bits);
134
135 // Protected functions, that are used by BitMap sub-classes that support them.
136
137 // Resize the backing bitmap memory.
138 //
139 // Old bits are transfered to the new memory
140 // and the extended memory is cleared.
141 template <class Allocator>
142 void resize(const Allocator& allocator, idx_t new_size_in_bits);
143
144 // Set up and clear the bitmap memory.
145 //
146 // Precondition: The bitmap was default constructed and has
147 // not yet had memory allocated via resize or (re)initialize.
148 template <class Allocator>
149 void initialize(const Allocator& allocator, idx_t size_in_bits);
150
151 // Set up and clear the bitmap memory.
152 //
153 // Can be called on previously initialized bitmaps.
154 template <class Allocator>
155 void reinitialize(const Allocator& allocator, idx_t new_size_in_bits);
156
157 // Set the map and size.
158 void update(bm_word_t* map, idx_t size) {
159 _map = map;
160 _size = size;
161 }
162
163 // Protected constructor and destructor.
164 BitMap(bm_word_t* map, idx_t size_in_bits) : _map(map), _size(size_in_bits) {}
165 ~BitMap() {}
166
167 public:
168 // Pretouch the entire range of memory this BitMap covers.
169 void pretouch();
170
171 // Accessing
172 static idx_t calc_size_in_words(size_t size_in_bits) {
173 return word_index(size_in_bits + BitsPerWord - 1);
174 }
175
176 static idx_t calc_size_in_bytes(size_t size_in_bits) {
177 return calc_size_in_words(size_in_bits) * BytesPerWord;
178 }
179
180 idx_t size() const { return _size; }
181 idx_t size_in_words() const { return calc_size_in_words(size()); }
182 idx_t size_in_bytes() const { return calc_size_in_bytes(size()); }
183
184 bool at(idx_t index) const {
185 verify_index(index);
186 return (*word_addr(index) & bit_mask(index)) != 0;
187 }
188
189 // Align bit index up or down to the next bitmap word boundary, or check
190 // alignment.
191 static idx_t word_align_up(idx_t bit) {
192 return align_up(bit, BitsPerWord);
193 }
194 static idx_t word_align_down(idx_t bit) {
195 return align_down(bit, BitsPerWord);
196 }
197 static bool is_word_aligned(idx_t bit) {
198 return word_align_up(bit) == bit;
199 }
200
201 // Set or clear the specified bit.
202 inline void set_bit(idx_t bit);
203 inline void clear_bit(idx_t bit);
204
205 // Atomically set or clear the specified bit.
206 inline bool par_set_bit(idx_t bit);
207 inline bool par_clear_bit(idx_t bit);
208
209 // Put the given value at the given offset. The parallel version
210 // will CAS the value into the bitmap and is quite a bit slower.
211 // The parallel version also returns a value indicating if the
212 // calling thread was the one that changed the value of the bit.
213 void at_put(idx_t index, bool value);
214 bool par_at_put(idx_t index, bool value);
215
216 // Update a range of bits. Ranges are half-open [beg, end).
217 void set_range (idx_t beg, idx_t end);
218 void clear_range (idx_t beg, idx_t end);
219 void set_large_range (idx_t beg, idx_t end);
220 void clear_large_range (idx_t beg, idx_t end);
221 void at_put_range(idx_t beg, idx_t end, bool value);
222 void par_at_put_range(idx_t beg, idx_t end, bool value);
223 void at_put_large_range(idx_t beg, idx_t end, bool value);
224 void par_at_put_large_range(idx_t beg, idx_t end, bool value);
225
226 // Update a range of bits, using a hint about the size. Currently only
227 // inlines the predominant case of a 1-bit range. Works best when hint is a
228 // compile-time constant.
229 void set_range(idx_t beg, idx_t end, RangeSizeHint hint);
230 void clear_range(idx_t beg, idx_t end, RangeSizeHint hint);
231 void par_set_range(idx_t beg, idx_t end, RangeSizeHint hint);
232 void par_clear_range (idx_t beg, idx_t end, RangeSizeHint hint);
233
234 // Clearing
235 void clear_large();
236 inline void clear();
237
238 // Iteration support. Returns "true" if the iteration completed, false
239 // if the iteration terminated early (because the closure "blk" returned
240 // false).
241 bool iterate(BitMapClosure* blk, idx_t leftIndex, idx_t rightIndex);
242 bool iterate(BitMapClosure* blk) {
243 // call the version that takes an interval
244 return iterate(blk, 0, size());
245 }
246
247 // Looking for 1's and 0's at indices equal to or greater than "l_index",
248 // stopping if none has been found before "r_index", and returning
249 // "r_index" (which must be at most "size") in that case.
250 idx_t get_next_one_offset (idx_t l_index, idx_t r_index) const;
251 idx_t get_next_zero_offset(idx_t l_index, idx_t r_index) const;
252
253 idx_t get_next_one_offset(idx_t offset) const {
254 return get_next_one_offset(offset, size());
255 }
256 idx_t get_next_zero_offset(idx_t offset) const {
257 return get_next_zero_offset(offset, size());
258 }
259
260 // Like "get_next_one_offset", except requires that "r_index" is
261 // aligned to bitsizeof(bm_word_t).
262 idx_t get_next_one_offset_aligned_right(idx_t l_index, idx_t r_index) const;
263
264 // Returns the number of bits set in the bitmap.
265 idx_t count_one_bits() const;
266
267 // Set operations.
268 void set_union(const BitMap& bits);
269 void set_difference(const BitMap& bits);
270 void set_intersection(const BitMap& bits);
271 // Returns true iff "this" is a superset of "bits".
272 bool contains(const BitMap& bits) const;
273 // Returns true iff "this and "bits" have a non-empty intersection.
274 bool intersects(const BitMap& bits) const;
275
276 // Returns result of whether this map changed
277 // during the operation
278 bool set_union_with_result(const BitMap& bits);
279 bool set_difference_with_result(const BitMap& bits);
280 bool set_intersection_with_result(const BitMap& bits);
281
282 void set_from(const BitMap& bits);
283
284 bool is_same(const BitMap& bits) const;
285
286 // Test if all bits are set or cleared
287 bool is_full() const;
288 bool is_empty() const;
289
290 void print_on_error(outputStream* st, const char* prefix) const;
291
292 #ifndef PRODUCT
293 public:
294 // Printing
295 void print_on(outputStream* st) const;
296 #endif
297 };
298
299 // A concrete implementation of the the "abstract" BitMap class.
300 //
301 // The BitMapView is used when the backing storage is managed externally.
302 class BitMapView : public BitMap {
303 public:
304 BitMapView() : BitMap(NULL, 0) {}
305 BitMapView(bm_word_t* map, idx_t size_in_bits) : BitMap(map, size_in_bits) {}
306 };
307
308 // A BitMap with storage in a ResourceArea.
309 class ResourceBitMap : public BitMap {
310
311 public:
312 ResourceBitMap() : BitMap(NULL, 0) {}
313 // Clears the bitmap memory.
314 ResourceBitMap(idx_t size_in_bits);
315
316 // Resize the backing bitmap memory.
317 //
318 // Old bits are transfered to the new memory
319 // and the extended memory is cleared.
320 void resize(idx_t new_size_in_bits);
321
322 // Set up and clear the bitmap memory.
323 //
324 // Precondition: The bitmap was default constructed and has
325 // not yet had memory allocated via resize or initialize.
326 void initialize(idx_t size_in_bits);
327
328 // Set up and clear the bitmap memory.
329 //
330 // Can be called on previously initialized bitmaps.
331 void reinitialize(idx_t size_in_bits);
332 };
333
334 // A BitMap with storage in a specific Arena.
335 class ArenaBitMap : public BitMap {
336 public:
337 // Clears the bitmap memory.
338 ArenaBitMap(Arena* arena, idx_t size_in_bits);
339
340 private:
341 // Don't allow copy or assignment.
342 ArenaBitMap(const ArenaBitMap&);
343 ArenaBitMap& operator=(const ArenaBitMap&);
344 };
345
346 // A BitMap with storage in the CHeap.
347 class CHeapBitMap : public BitMap {
348
349 private:
350 // Don't allow copy or assignment, to prevent the
351 // allocated memory from leaking out to other instances.
352 CHeapBitMap(const CHeapBitMap&);
353 CHeapBitMap& operator=(const CHeapBitMap&);
354
355 // NMT memory type
356 MEMFLAGS _flags;
357
358 public:
359 CHeapBitMap(MEMFLAGS flags = mtInternal) : BitMap(NULL, 0), _flags(flags) {}
360 // Clears the bitmap memory.
361 CHeapBitMap(idx_t size_in_bits, MEMFLAGS flags = mtInternal);
362 ~CHeapBitMap();
363
364 // Resize the backing bitmap memory.
365 //
366 // Old bits are transfered to the new memory
367 // and the extended memory is cleared.
368 void resize(idx_t new_size_in_bits);
369
370 // Set up and clear the bitmap memory.
371 //
372 // Precondition: The bitmap was default constructed and has
373 // not yet had memory allocated via resize or initialize.
374 void initialize(idx_t size_in_bits);
375
376 // Set up and clear the bitmap memory.
377 //
378 // Can be called on previously initialized bitmaps.
379 void reinitialize(idx_t size_in_bits);
380 };
381
382 // Convenience class wrapping BitMap which provides multiple bits per slot.
383 class BitMap2D {
384 public:
385 typedef BitMap::idx_t idx_t; // Type used for bit and word indices.
386 typedef BitMap::bm_word_t bm_word_t; // Element type of array that
387 // represents the bitmap.
388 private:
389 ResourceBitMap _map;
390 idx_t _bits_per_slot;
391
392 idx_t bit_index(idx_t slot_index, idx_t bit_within_slot_index) const {
393 return slot_index * _bits_per_slot + bit_within_slot_index;
394 }
395
396 void verify_bit_within_slot_index(idx_t index) const {
397 assert(index < _bits_per_slot, "bit_within_slot index out of bounds");
398 }
399
400 public:
401 // Construction. bits_per_slot must be greater than 0.
402 BitMap2D(idx_t bits_per_slot) :
403 _map(), _bits_per_slot(bits_per_slot) {}
404
405 // Allocates necessary data structure in resource area. bits_per_slot must be greater than 0.
406 BitMap2D(idx_t size_in_slots, idx_t bits_per_slot) :
407 _map(size_in_slots * bits_per_slot), _bits_per_slot(bits_per_slot) {}
408
409 idx_t size_in_bits() {
410 return _map.size();
411 }
412
413 // Returns number of full slots that have been allocated
414 idx_t size_in_slots() {
415 // Round down
416 return _map.size() / _bits_per_slot;
417 }
418
419 bool is_valid_index(idx_t slot_index, idx_t bit_within_slot_index);
420 bool at(idx_t slot_index, idx_t bit_within_slot_index) const;
421 void set_bit(idx_t slot_index, idx_t bit_within_slot_index);
422 void clear_bit(idx_t slot_index, idx_t bit_within_slot_index);
423 void at_put(idx_t slot_index, idx_t bit_within_slot_index, bool value);
424 void at_put_grow(idx_t slot_index, idx_t bit_within_slot_index, bool value);
425 };
426
427 // Closure for iterating over BitMaps
428
429 class BitMapClosure {
430 public:
431 // Callback when bit in map is set. Should normally return "true";
432 // return of false indicates that the bitmap iteration should terminate.
433 virtual bool do_bit(BitMap::idx_t offset) = 0;
434 };
435
436 #endif // SHARE_VM_UTILITIES_BITMAP_HPP