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