1 /*
2 * Copyright (c) 1997, 2009, 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.
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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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23 */
24
25 // Forward decl;
26 class BitMapClosure;
27
28 // Operations for bitmaps represented as arrays of unsigned integers.
29 // Bit offsets are numbered from 0 to size-1.
30
31 class BitMap VALUE_OBJ_CLASS_SPEC {
32 friend class BitMap2D;
33
34 public:
35 typedef size_t idx_t; // Type used for bit and word indices.
36 typedef uintptr_t bm_word_t; // Element type of array that represents
37 // the bitmap.
38
39 // Hints for range sizes.
40 typedef enum {
41 unknown_range, small_range, large_range
42 } RangeSizeHint;
43
44 private:
45 bm_word_t* _map; // First word in bitmap
46 idx_t _size; // Size of bitmap (in bits)
47
48 // Puts the given value at the given offset, using resize() to size
49 // the bitmap appropriately if needed using factor-of-two expansion.
50 void at_put_grow(idx_t index, bool value);
51
52 protected:
53 // Return the position of bit within the word that contains it (e.g., if
54 // bitmap words are 32 bits, return a number 0 <= n <= 31).
55 static idx_t bit_in_word(idx_t bit) { return bit & (BitsPerWord - 1); }
56
57 // Return a mask that will select the specified bit, when applied to the word
58 // containing the bit.
59 static bm_word_t bit_mask(idx_t bit) { return (bm_word_t)1 << bit_in_word(bit); }
60
61 // Return the index of the word containing the specified bit.
62 static idx_t word_index(idx_t bit) { return bit >> LogBitsPerWord; }
63
64 // Return the bit number of the first bit in the specified word.
65 static idx_t bit_index(idx_t word) { return word << LogBitsPerWord; }
66
67 // Return the array of bitmap words, or a specific word from it.
68 bm_word_t* map() const { return _map; }
69 bm_word_t map(idx_t word) const { return _map[word]; }
70
71 // Return a pointer to the word containing the specified bit.
72 bm_word_t* word_addr(idx_t bit) const { return map() + word_index(bit); }
73
74 // Set a word to a specified value or to all ones; clear a word.
75 void set_word (idx_t word, bm_word_t val) { _map[word] = val; }
76 void set_word (idx_t word) { set_word(word, ~(uintptr_t)0); }
77 void clear_word(idx_t word) { _map[word] = 0; }
78
79 // Utilities for ranges of bits. Ranges are half-open [beg, end).
80
81 // Ranges within a single word.
82 bm_word_t inverted_bit_mask_for_range(idx_t beg, idx_t end) const;
83 void set_range_within_word (idx_t beg, idx_t end);
84 void clear_range_within_word (idx_t beg, idx_t end);
85 void par_put_range_within_word (idx_t beg, idx_t end, bool value);
86
87 // Ranges spanning entire words.
88 void set_range_of_words (idx_t beg, idx_t end);
89 void clear_range_of_words (idx_t beg, idx_t end);
90 void set_large_range_of_words (idx_t beg, idx_t end);
91 void clear_large_range_of_words (idx_t beg, idx_t end);
92
93 // The index of the first full word in a range.
94 idx_t word_index_round_up(idx_t bit) const;
95
96 // Verification.
97 inline void verify_index(idx_t index) const NOT_DEBUG_RETURN;
98 inline void verify_range(idx_t beg_index, idx_t end_index) const
99 NOT_DEBUG_RETURN;
100
101 // Statistics.
102 static idx_t* _pop_count_table;
103 static void init_pop_count_table();
104 static idx_t num_set_bits(bm_word_t w);
105 static idx_t num_set_bits_from_table(unsigned char c);
106
107 public:
108
109 // Constructs a bitmap with no map, and size 0.
110 BitMap() : _map(NULL), _size(0) {}
111
112 // Constructs a bitmap with the given map and size.
113 BitMap(bm_word_t* map, idx_t size_in_bits);
114
115 // Constructs an empty bitmap of the given size (that is, this clears the
116 // new bitmap). Allocates the map array in resource area if
117 // "in_resource_area" is true, else in the C heap.
118 BitMap(idx_t size_in_bits, bool in_resource_area = true);
119
120 // Set the map and size.
121 void set_map(bm_word_t* map) { _map = map; }
122 void set_size(idx_t size_in_bits) { _size = size_in_bits; }
123
124 // Allocates necessary data structure, either in the resource area
125 // or in the C heap, as indicated by "in_resource_area."
126 // Preserves state currently in bit map by copying data.
127 // Zeros any newly-addressable bits.
128 // If "in_resource_area" is false, frees the current map.
129 // (Note that this assumes that all calls to "resize" on the same BitMap
130 // use the same value for "in_resource_area".)
131 void resize(idx_t size_in_bits, bool in_resource_area = true);
132
133 // Accessing
134 idx_t size() const { return _size; }
135 idx_t size_in_words() const {
136 return word_index(size() + BitsPerWord - 1);
137 }
138
139 bool at(idx_t index) const {
140 verify_index(index);
141 return (*word_addr(index) & bit_mask(index)) != 0;
142 }
143
144 // Align bit index up or down to the next bitmap word boundary, or check
145 // alignment.
146 static idx_t word_align_up(idx_t bit) {
147 return align_size_up(bit, BitsPerWord);
148 }
149 static idx_t word_align_down(idx_t bit) {
150 return align_size_down(bit, BitsPerWord);
151 }
152 static bool is_word_aligned(idx_t bit) {
153 return word_align_up(bit) == bit;
154 }
155
156 // Set or clear the specified bit.
157 inline void set_bit(idx_t bit);
158 void clear_bit(idx_t bit);
159
160 // Atomically set or clear the specified bit.
161 bool par_set_bit(idx_t bit);
162 bool par_clear_bit(idx_t bit);
163
164 // Put the given value at the given offset. The parallel version
165 // will CAS the value into the bitmap and is quite a bit slower.
166 // The parallel version also returns a value indicating if the
167 // calling thread was the one that changed the value of the bit.
168 void at_put(idx_t index, bool value);
169 bool par_at_put(idx_t index, bool value);
170
171 // Update a range of bits. Ranges are half-open [beg, end).
172 void set_range (idx_t beg, idx_t end);
173 void clear_range (idx_t beg, idx_t end);
174 void set_large_range (idx_t beg, idx_t end);
175 void clear_large_range (idx_t beg, idx_t end);
176 void at_put_range(idx_t beg, idx_t end, bool value);
177 void par_at_put_range(idx_t beg, idx_t end, bool value);
178 void at_put_large_range(idx_t beg, idx_t end, bool value);
179 void par_at_put_large_range(idx_t beg, idx_t end, bool value);
180
181 // Update a range of bits, using a hint about the size. Currently only
182 // inlines the predominant case of a 1-bit range. Works best when hint is a
183 // compile-time constant.
184 void set_range(idx_t beg, idx_t end, RangeSizeHint hint);
185 void clear_range(idx_t beg, idx_t end, RangeSizeHint hint);
186 void par_set_range(idx_t beg, idx_t end, RangeSizeHint hint);
187 void par_clear_range (idx_t beg, idx_t end, RangeSizeHint hint);
188
189 // It performs the union operation between subsets of equal length
190 // of two bitmaps (the target bitmap of the method and the
191 // from_bitmap) and stores the result to the target bitmap. The
192 // from_start_index represents the first bit index of the subrange
193 // of the from_bitmap. The to_start_index is the equivalent of the
194 // target bitmap. Both indexes should be word-aligned, i.e. they
195 // should correspond to the first bit on a bitmap word (it's up to
196 // the caller to ensure this; the method does check it). The length
197 // of the subset is specified with word_num and it is in number of
198 // bitmap words. The caller should ensure that this is at least 2
199 // (smaller ranges are not support to save extra checks). Again,
200 // this is checked in the method.
201 //
202 // Atomicity concerns: it is assumed that any contention on the
203 // target bitmap with other threads will happen on the first and
204 // last words; the ones in between will be "owned" exclusively by
205 // the calling thread and, in fact, they will already be 0. So, the
206 // method performs a CAS on the first word, copies the next
207 // word_num-2 words, and finally performs a CAS on the last word.
208 void mostly_disjoint_range_union(BitMap* from_bitmap,
209 idx_t from_start_index,
210 idx_t to_start_index,
211 size_t word_num);
212
213
214 // Clearing
215 void clear_large();
216 inline void clear();
217
218 // Iteration support. Returns "true" if the iteration completed, false
219 // if the iteration terminated early (because the closure "blk" returned
220 // false).
221 bool iterate(BitMapClosure* blk, idx_t leftIndex, idx_t rightIndex);
222 bool iterate(BitMapClosure* blk) {
223 // call the version that takes an interval
224 return iterate(blk, 0, size());
225 }
226
227 // Looking for 1's and 0's at indices equal to or greater than "l_index",
228 // stopping if none has been found before "r_index", and returning
229 // "r_index" (which must be at most "size") in that case.
230 idx_t get_next_one_offset_inline (idx_t l_index, idx_t r_index) const;
231 idx_t get_next_zero_offset_inline(idx_t l_index, idx_t r_index) const;
232
233 // Like "get_next_one_offset_inline", except requires that "r_index" is
234 // aligned to bitsizeof(bm_word_t).
235 idx_t get_next_one_offset_inline_aligned_right(idx_t l_index,
236 idx_t r_index) const;
237
238 // Non-inline versionsof the above.
239 idx_t get_next_one_offset (idx_t l_index, idx_t r_index) const;
240 idx_t get_next_zero_offset(idx_t l_index, idx_t r_index) const;
241
242 idx_t get_next_one_offset(idx_t offset) const {
243 return get_next_one_offset(offset, size());
244 }
245 idx_t get_next_zero_offset(idx_t offset) const {
246 return get_next_zero_offset(offset, size());
247 }
248
249 // Returns the number of bits set in the bitmap.
250 idx_t count_one_bits() const;
251
252 // Set operations.
253 void set_union(BitMap bits);
254 void set_difference(BitMap bits);
255 void set_intersection(BitMap bits);
256 // Returns true iff "this" is a superset of "bits".
257 bool contains(const BitMap bits) const;
258 // Returns true iff "this and "bits" have a non-empty intersection.
259 bool intersects(const BitMap bits) const;
260
261 // Returns result of whether this map changed
262 // during the operation
263 bool set_union_with_result(BitMap bits);
264 bool set_difference_with_result(BitMap bits);
265 bool set_intersection_with_result(BitMap bits);
266
267 // Requires the submap of "bits" starting at offset to be at least as
268 // large as "this". Modifies "this" to be the intersection of its
269 // current contents and the submap of "bits" starting at "offset" of the
270 // same length as "this."
271 // (For expedience, currently requires the offset to be aligned to the
272 // bitsize of a uintptr_t. This should go away in the future though it
273 // will probably remain a good case to optimize.)
274 void set_intersection_at_offset(BitMap bits, idx_t offset);
275
276 void set_from(BitMap bits);
277
278 bool is_same(BitMap bits);
279
280 // Test if all bits are set or cleared
281 bool is_full() const;
282 bool is_empty() const;
283
284
285 #ifndef PRODUCT
286 public:
287 // Printing
288 void print_on(outputStream* st) const;
289 #endif
290 };
291
292 // Convenience class wrapping BitMap which provides multiple bits per slot.
293 class BitMap2D VALUE_OBJ_CLASS_SPEC {
294 public:
295 typedef BitMap::idx_t idx_t; // Type used for bit and word indices.
296 typedef BitMap::bm_word_t bm_word_t; // Element type of array that
297 // represents the bitmap.
298 private:
299 BitMap _map;
300 idx_t _bits_per_slot;
301
302 idx_t bit_index(idx_t slot_index, idx_t bit_within_slot_index) const {
303 return slot_index * _bits_per_slot + bit_within_slot_index;
304 }
305
306 void verify_bit_within_slot_index(idx_t index) const {
307 assert(index < _bits_per_slot, "bit_within_slot index out of bounds");
308 }
309
310 public:
311 // Construction. bits_per_slot must be greater than 0.
312 BitMap2D(bm_word_t* map, idx_t size_in_slots, idx_t bits_per_slot);
313
314 // Allocates necessary data structure in resource area. bits_per_slot must be greater than 0.
315 BitMap2D(idx_t size_in_slots, idx_t bits_per_slot);
316
317 idx_t size_in_bits() {
318 return _map.size();
319 }
320
321 // Returns number of full slots that have been allocated
322 idx_t size_in_slots() {
323 // Round down
324 return _map.size() / _bits_per_slot;
325 }
326
327 bool is_valid_index(idx_t slot_index, idx_t bit_within_slot_index) {
328 verify_bit_within_slot_index(bit_within_slot_index);
329 return (bit_index(slot_index, bit_within_slot_index) < size_in_bits());
330 }
331
332 bool at(idx_t slot_index, idx_t bit_within_slot_index) const {
333 verify_bit_within_slot_index(bit_within_slot_index);
334 return _map.at(bit_index(slot_index, bit_within_slot_index));
335 }
336
337 void set_bit(idx_t slot_index, idx_t bit_within_slot_index) {
338 verify_bit_within_slot_index(bit_within_slot_index);
339 _map.set_bit(bit_index(slot_index, bit_within_slot_index));
340 }
341
342 void clear_bit(idx_t slot_index, idx_t bit_within_slot_index) {
343 verify_bit_within_slot_index(bit_within_slot_index);
344 _map.clear_bit(bit_index(slot_index, bit_within_slot_index));
345 }
346
347 void at_put(idx_t slot_index, idx_t bit_within_slot_index, bool value) {
348 verify_bit_within_slot_index(bit_within_slot_index);
349 _map.at_put(bit_index(slot_index, bit_within_slot_index), value);
350 }
351
352 void at_put_grow(idx_t slot_index, idx_t bit_within_slot_index, bool value) {
353 verify_bit_within_slot_index(bit_within_slot_index);
354 _map.at_put_grow(bit_index(slot_index, bit_within_slot_index), value);
355 }
356
357 void clear();
358 };
359
360 // Closure for iterating over BitMaps
361
362 class BitMapClosure VALUE_OBJ_CLASS_SPEC {
363 public:
364 // Callback when bit in map is set. Should normally return "true";
365 // return of false indicates that the bitmap iteration should terminate.
366 virtual bool do_bit(BitMap::idx_t offset) = 0;
367 };