1 /*
2 * Copyright (c) 1997, 2010, 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,
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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 bm_word_t* _map; // First word in bitmap
52 idx_t _size; // Size of bitmap (in bits)
53
54 // Puts the given value at the given offset, using resize() to size
55 // the bitmap appropriately if needed using factor-of-two expansion.
56 void at_put_grow(idx_t index, bool value);
57
58 protected:
59 // Return the position of bit within the word that contains it (e.g., if
60 // bitmap words are 32 bits, return a number 0 <= n <= 31).
61 static idx_t bit_in_word(idx_t bit) { return bit & (BitsPerWord - 1); }
62
63 // Return a mask that will select the specified bit, when applied to the word
64 // containing the bit.
65 static bm_word_t bit_mask(idx_t bit) { return (bm_word_t)1 << bit_in_word(bit); }
66
67 // Return the index of the word containing the specified bit.
68 static idx_t word_index(idx_t bit) { return bit >> LogBitsPerWord; }
69
70 // Return the bit number of the first bit in the specified word.
71 static idx_t bit_index(idx_t word) { return word << LogBitsPerWord; }
72
73 // Return the array of bitmap words, or a specific word from it.
74 bm_word_t* map() const { return _map; }
75 bm_word_t map(idx_t word) const { return _map[word]; }
76
77 // Return a pointer to the word containing the specified bit.
78 bm_word_t* word_addr(idx_t bit) const { return map() + word_index(bit); }
79
80 // Set a word to a specified value or to all ones; clear a word.
81 void set_word (idx_t word, bm_word_t val) { _map[word] = val; }
82 void set_word (idx_t word) { set_word(word, ~(uintptr_t)0); }
83 void clear_word(idx_t word) { _map[word] = 0; }
84
85 // Utilities for ranges of bits. Ranges are half-open [beg, end).
86
87 // Ranges within a single word.
88 bm_word_t inverted_bit_mask_for_range(idx_t beg, idx_t end) const;
89 void set_range_within_word (idx_t beg, idx_t end);
90 void clear_range_within_word (idx_t beg, idx_t end);
91 void par_put_range_within_word (idx_t beg, idx_t end, bool value);
92
93 // Ranges spanning entire words.
94 void set_range_of_words (idx_t beg, idx_t end);
95 void clear_range_of_words (idx_t beg, idx_t end);
96 void set_large_range_of_words (idx_t beg, idx_t end);
97 void clear_large_range_of_words (idx_t beg, idx_t end);
98
99 // The index of the first full word in a range.
100 idx_t word_index_round_up(idx_t bit) const;
101
102 // Verification.
103 inline void verify_index(idx_t index) const NOT_DEBUG_RETURN;
104 inline void verify_range(idx_t beg_index, idx_t end_index) const
105 NOT_DEBUG_RETURN;
106
107 // Statistics.
108 static idx_t* _pop_count_table;
109 static void init_pop_count_table();
110 static idx_t num_set_bits(bm_word_t w);
111 static idx_t num_set_bits_from_table(unsigned char c);
112
113 public:
114
115 // Constructs a bitmap with no map, and size 0.
116 BitMap() : _map(NULL), _size(0) {}
117
118 // Constructs a bitmap with the given map and size.
119 BitMap(bm_word_t* map, idx_t size_in_bits);
120
121 // Constructs an empty bitmap of the given size (that is, this clears the
122 // new bitmap). Allocates the map array in resource area if
123 // "in_resource_area" is true, else in the C heap.
124 BitMap(idx_t size_in_bits, bool in_resource_area = true);
125
126 // Set the map and size.
127 void set_map(bm_word_t* map) { _map = map; }
128 void set_size(idx_t size_in_bits) { _size = size_in_bits; }
129
130 // Allocates necessary data structure, either in the resource area
131 // or in the C heap, as indicated by "in_resource_area."
132 // Preserves state currently in bit map by copying data.
133 // Zeros any newly-addressable bits.
134 // If "in_resource_area" is false, frees the current map.
135 // (Note that this assumes that all calls to "resize" on the same BitMap
136 // use the same value for "in_resource_area".)
137 void resize(idx_t size_in_bits, bool in_resource_area = true);
138
139 // Accessing
140 idx_t size() const { return _size; }
141 idx_t size_in_words() const {
142 return word_index(size() + BitsPerWord - 1);
143 }
144
145 bool at(idx_t index) const {
146 verify_index(index);
147 return (*word_addr(index) & bit_mask(index)) != 0;
148 }
149
150 // Align bit index up or down to the next bitmap word boundary, or check
151 // alignment.
152 static idx_t word_align_up(idx_t bit) {
153 return align_size_up(bit, BitsPerWord);
154 }
155 static idx_t word_align_down(idx_t bit) {
156 return align_size_down(bit, BitsPerWord);
157 }
158 static bool is_word_aligned(idx_t bit) {
159 return word_align_up(bit) == bit;
160 }
161
162 // Set or clear the specified bit.
163 inline void set_bit(idx_t bit);
164 void clear_bit(idx_t bit);
165
166 // Atomically set or clear the specified bit.
167 bool par_set_bit(idx_t bit);
168 bool par_clear_bit(idx_t bit);
169
170 // Put the given value at the given offset. The parallel version
171 // will CAS the value into the bitmap and is quite a bit slower.
172 // The parallel version also returns a value indicating if the
173 // calling thread was the one that changed the value of the bit.
174 void at_put(idx_t index, bool value);
175 bool par_at_put(idx_t index, bool value);
176
177 // Update a range of bits. Ranges are half-open [beg, end).
178 void set_range (idx_t beg, idx_t end);
179 void clear_range (idx_t beg, idx_t end);
180 void set_large_range (idx_t beg, idx_t end);
181 void clear_large_range (idx_t beg, idx_t end);
182 void at_put_range(idx_t beg, idx_t end, bool value);
183 void par_at_put_range(idx_t beg, idx_t end, bool value);
184 void at_put_large_range(idx_t beg, idx_t end, bool value);
185 void par_at_put_large_range(idx_t beg, idx_t end, bool value);
186
187 // Update a range of bits, using a hint about the size. Currently only
188 // inlines the predominant case of a 1-bit range. Works best when hint is a
189 // compile-time constant.
190 void set_range(idx_t beg, idx_t end, RangeSizeHint hint);
191 void clear_range(idx_t beg, idx_t end, RangeSizeHint hint);
192 void par_set_range(idx_t beg, idx_t end, RangeSizeHint hint);
193 void par_clear_range (idx_t beg, idx_t end, RangeSizeHint hint);
194
195 // It performs the union operation between subsets of equal length
196 // of two bitmaps (the target bitmap of the method and the
197 // from_bitmap) and stores the result to the target bitmap. The
198 // from_start_index represents the first bit index of the subrange
199 // of the from_bitmap. The to_start_index is the equivalent of the
200 // target bitmap. Both indexes should be word-aligned, i.e. they
201 // should correspond to the first bit on a bitmap word (it's up to
202 // the caller to ensure this; the method does check it). The length
203 // of the subset is specified with word_num and it is in number of
204 // bitmap words. The caller should ensure that this is at least 2
205 // (smaller ranges are not support to save extra checks). Again,
206 // this is checked in the method.
207 //
208 // Atomicity concerns: it is assumed that any contention on the
209 // target bitmap with other threads will happen on the first and
210 // last words; the ones in between will be "owned" exclusively by
211 // the calling thread and, in fact, they will already be 0. So, the
212 // method performs a CAS on the first word, copies the next
213 // word_num-2 words, and finally performs a CAS on the last word.
214 void mostly_disjoint_range_union(BitMap* from_bitmap,
215 idx_t from_start_index,
216 idx_t to_start_index,
217 size_t word_num);
218
219
220 // Clearing
221 void clear_large();
222 inline void clear();
223
224 // Iteration support. Returns "true" if the iteration completed, false
225 // if the iteration terminated early (because the closure "blk" returned
226 // false).
227 bool iterate(BitMapClosure* blk, idx_t leftIndex, idx_t rightIndex);
228 bool iterate(BitMapClosure* blk) {
229 // call the version that takes an interval
230 return iterate(blk, 0, size());
231 }
232
233 // Looking for 1's and 0's at indices equal to or greater than "l_index",
234 // stopping if none has been found before "r_index", and returning
235 // "r_index" (which must be at most "size") in that case.
236 idx_t get_next_one_offset_inline (idx_t l_index, idx_t r_index) const;
237 idx_t get_next_zero_offset_inline(idx_t l_index, idx_t r_index) const;
238
239 // Like "get_next_one_offset_inline", except requires that "r_index" is
240 // aligned to bitsizeof(bm_word_t).
241 idx_t get_next_one_offset_inline_aligned_right(idx_t l_index,
242 idx_t r_index) const;
243
244 // Non-inline versionsof the above.
245 idx_t get_next_one_offset (idx_t l_index, idx_t r_index) const;
246 idx_t get_next_zero_offset(idx_t l_index, idx_t r_index) const;
247
248 idx_t get_next_one_offset(idx_t offset) const {
249 return get_next_one_offset(offset, size());
250 }
251 idx_t get_next_zero_offset(idx_t offset) const {
252 return get_next_zero_offset(offset, size());
253 }
254
255 // Returns the number of bits set in the bitmap.
256 idx_t count_one_bits() const;
257
258 // Set operations.
259 void set_union(BitMap bits);
260 void set_difference(BitMap bits);
261 void set_intersection(BitMap bits);
262 // Returns true iff "this" is a superset of "bits".
263 bool contains(const BitMap bits) const;
264 // Returns true iff "this and "bits" have a non-empty intersection.
265 bool intersects(const BitMap bits) const;
266
267 // Returns result of whether this map changed
268 // during the operation
269 bool set_union_with_result(BitMap bits);
270 bool set_difference_with_result(BitMap bits);
271 bool set_intersection_with_result(BitMap bits);
272
273 // Requires the submap of "bits" starting at offset to be at least as
274 // large as "this". Modifies "this" to be the intersection of its
275 // current contents and the submap of "bits" starting at "offset" of the
276 // same length as "this."
277 // (For expedience, currently requires the offset to be aligned to the
278 // bitsize of a uintptr_t. This should go away in the future though it
279 // will probably remain a good case to optimize.)
280 void set_intersection_at_offset(BitMap bits, idx_t offset);
281
282 void set_from(BitMap bits);
283
284 bool is_same(BitMap bits);
285
286 // Test if all bits are set or cleared
287 bool is_full() const;
288 bool is_empty() const;
289
290
291 #ifndef PRODUCT
292 public:
293 // Printing
294 void print_on(outputStream* st) const;
295 #endif
296 };
297
298 // Convenience class wrapping BitMap which provides multiple bits per slot.
299 class BitMap2D VALUE_OBJ_CLASS_SPEC {
300 public:
301 typedef BitMap::idx_t idx_t; // Type used for bit and word indices.
302 typedef BitMap::bm_word_t bm_word_t; // Element type of array that
303 // represents the bitmap.
304 private:
305 BitMap _map;
306 idx_t _bits_per_slot;
307
308 idx_t bit_index(idx_t slot_index, idx_t bit_within_slot_index) const {
309 return slot_index * _bits_per_slot + bit_within_slot_index;
310 }
311
312 void verify_bit_within_slot_index(idx_t index) const {
313 assert(index < _bits_per_slot, "bit_within_slot index out of bounds");
314 }
315
316 public:
317 // Construction. bits_per_slot must be greater than 0.
318 BitMap2D(bm_word_t* map, idx_t size_in_slots, idx_t bits_per_slot);
319
320 // Allocates necessary data structure in resource area. bits_per_slot must be greater than 0.
321 BitMap2D(idx_t size_in_slots, idx_t bits_per_slot);
322
323 idx_t size_in_bits() {
324 return _map.size();
325 }
326
327 // Returns number of full slots that have been allocated
328 idx_t size_in_slots() {
329 // Round down
330 return _map.size() / _bits_per_slot;
331 }
332
333 bool is_valid_index(idx_t slot_index, idx_t bit_within_slot_index) {
334 verify_bit_within_slot_index(bit_within_slot_index);
335 return (bit_index(slot_index, bit_within_slot_index) < size_in_bits());
336 }
337
338 bool at(idx_t slot_index, idx_t bit_within_slot_index) const {
339 verify_bit_within_slot_index(bit_within_slot_index);
340 return _map.at(bit_index(slot_index, bit_within_slot_index));
341 }
342
343 void set_bit(idx_t slot_index, idx_t bit_within_slot_index) {
344 verify_bit_within_slot_index(bit_within_slot_index);
345 _map.set_bit(bit_index(slot_index, bit_within_slot_index));
346 }
347
348 void clear_bit(idx_t slot_index, idx_t bit_within_slot_index) {
349 verify_bit_within_slot_index(bit_within_slot_index);
350 _map.clear_bit(bit_index(slot_index, bit_within_slot_index));
351 }
352
353 void at_put(idx_t slot_index, idx_t bit_within_slot_index, bool value) {
354 verify_bit_within_slot_index(bit_within_slot_index);
355 _map.at_put(bit_index(slot_index, bit_within_slot_index), value);
356 }
357
358 void at_put_grow(idx_t slot_index, idx_t bit_within_slot_index, bool value) {
359 verify_bit_within_slot_index(bit_within_slot_index);
360 _map.at_put_grow(bit_index(slot_index, bit_within_slot_index), value);
361 }
362
363 void clear();
364 };
365
366 // Closure for iterating over BitMaps
367
368 class BitMapClosure VALUE_OBJ_CLASS_SPEC {
369 public:
370 // Callback when bit in map is set. Should normally return "true";
371 // return of false indicates that the bitmap iteration should terminate.
372 virtual bool do_bit(BitMap::idx_t offset) = 0;
373 };
374
375 #endif // SHARE_VM_UTILITIES_BITMAP_HPP